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In mice, the first liver-resident macrophages, known as Kupffer cells (KCs), are thought to derive from yolk sac (YS) hematopoietic progenitors that are specified prior to the emergence of the hematopoietic stem cell (HSC). To investigate human KC development, we recapitulated YS-like hematopoiesis from human pluripotent stem cells (hPSCs) and transplanted derivative macrophage progenitors into NSG mice previously humanized with hPSC-liver sinusoidal endothelial cells (LSECs). We demonstrate that hPSC-LSECs facilitate stable hPSC-YS-macrophage engraftment for at least 7 weeks. Single-cell RNA sequencing (scRNA-seq) of engrafted YS-macrophages revealed a homogeneous MARCO-expressing KC gene signature and low expression of monocyte-like macrophage genes. In contrast, human cord blood (CB)-derived macrophage progenitors generated grafts that contain multiple hematopoietic lineages in addition to KCs. Functional analyses showed that the engrafted KCs actively perform phagocytosis and erythrophagocytosis in vivo. Taken together, these findings demonstrate that it is possible to generate human KCs from hPSC-derived, YS-like progenitors., Competing Interests: Declaration of interests G.M. Keller is a founding investigator and a paid consultant for BlueRock Therapeutics LP and a paid consultant for VistaGen Therapeutics and Apiary Therapeutics., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

The intricate anatomical structure and high cellular density of the myocardium complicate the bioengineering of perfusable vascular networks within cardiac tissues. In vivo neonatal studies highlight the key role of resident cardiac macrophages in post-injury regeneration and angiogenesis. Here, we integrate human pluripotent stem-cell-derived primitive yolk-sac-like macrophages within vascularized heart-on-chip platforms. Macrophage incorporation profoundly impacted the functionality and perfusability of microvascularized cardiac tissues up to 2 weeks of culture. Macrophages mitigated tissue cytotoxicity and the release of cell-free mitochondrial DNA (mtDNA), while upregulating the secretion of pro-angiogenic, matrix remodeling, and cardioprotective cytokines. Bulk RNA sequencing (RNA-seq) revealed an upregulation of cardiac maturation and angiogenesis genes. Further, single-nuclei RNA sequencing (snRNA-seq) and secretome data suggest that macrophages may prime stromal cells for vascular development by inducing insulin like growth factor binding protein 7 (IGFBP7) and hepatocyte growth factor (HGF) expression. Our results underscore the vital role of primitive macrophages in the long-term vascularization of cardiac tissues, offering insights for therapy and advancing heart-on-a-chip technologies., Competing Interests: Declaration of interests M.R. and Y.Z. are inventors on an issued patent that describes Biowire technology. This patent is licensed to Valo Health. M.R. and Y.Z. receive licensing revenue., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Yolk sac macrophages are the first to seed the developing heart, however we have no understanding of their roles in human heart development and function due to a lack of accessible tissue. Here, we bridge this gap by differentiating human embryonic stem cells (hESCs) into primitive LYVE1 + macrophages (hESC-macrophages) that stably engraft within contractile cardiac microtissues composed of hESC-cardiomyocytes and fibroblasts. Engraftment induces a human fetal cardiac macrophage gene program enriched in efferocytic pathways. Functionally, hESC-macrophages trigger cardiomyocyte sarcomeric protein maturation, enhance contractile force and improve relaxation kinetics. Mechanistically, hESC-macrophages engage in phosphatidylserine dependent ingestion of apoptotic cardiomyocyte cargo, which reduces microtissue stress, leading hESC-cardiomyocytes to more closely resemble early human fetal ventricular cardiomyocytes, both transcriptionally and metabolically. Inhibiting hESC-macrophage efferocytosis impairs sarcomeric protein maturation and reduces cardiac microtissue function. Taken together, macrophage-engineered human cardiac microtissues represent a considerably improved model for human heart development, and reveal a major beneficial role for human primitive macrophages in enhancing early cardiac tissue function., Competing Interests: Competing interests M. R. and Y.Z. are inventors on patents for cardiac tissue cultivation that are licensed to Valo Health. They receive licensing royalty from this invention. Q.W., M.R., and Y.Z. have a filed patent application on thermoplastic polymer composition for micro 3D printing and uses thereof. All other authors declare no competing interests.

The oceanic crust extends over two-thirds of the Earth's solid surface, and is generated along mid-ocean ridges from melts derived from the upwelling mantle. The upper and middle crust are constructed by dyking and sea-floor eruptions originating from magma accumulated in mid-crustal lenses at the spreading axis, but the style of accretion of the lower oceanic crust is actively debated. Models based on geological and petrological data from ophiolites propose that the lower oceanic crust is accreted from melt sills intruded at multiple levels between the Moho transition zone (MTZ) and the mid-crustal lens, consistent with geophysical studies that suggest the presence of melt within the lower crust. However, seismic images of molten sills within the lower crust have been elusive. Until now, only seismic reflections from mid-crustal melt lenses and sills within the MTZ have been described, suggesting that melt is efficiently transported through the lower crust. Here we report deep crustal seismic reflections off the southern Juan de Fuca ridge that we interpret as originating from a molten sill at present accreting the lower oceanic crust. The sill sits 5-6 km beneath the sea floor and 850-900 m above the MTZ, and is located 1.4-3.2 km off the spreading axis. Our results provide evidence for the existence of low-permeability barriers to melt migration within the lower section of modern oceanic crust forming at intermediate-to-fast spreading rates, as inferred from ophiolite studies.

Constraints on the structure of rifted continental margins and the magmatism resulting from such rifting can help refine our understanding of the strength of the lithosphere, the state of the underlying mantle and the transition from rifting to seafloor spreading. An important structural classification of rifts is by width, with narrow rifts thought to form as necking instabilities (where extension rates outpace thermal diffusion) and wide rifts thought to require a mechanism to inhibit localization, such as lower-crustal flow in high heat-flow settings. Observations of the magmatism that results from rifting range from volcanic margins with two to three times the magmatism predicted from melting models to non-volcanic margins with almost no rift or post-rift magmatism. Such variations in magmatic activity are commonly attributed to variations in mantle temperature. Here we describe results from the PESCADOR seismic experiment in the southern Gulf of California and present crustal-scale images across three rift segments. Over short lateral distances, we observe large differences in rifting style and magmatism--from wide rifting with minor synchronous magmatism to narrow rifting in magmatically robust segments. But many of the factors believed to control structural evolution and magmatism during rifting (extension rate, mantle potential temperature and heat flow) tend to vary over larger length scales. We conclude instead that mantle depletion, rather than low mantle temperature, accounts for the observed wide, magma-poor margins, and that mantle fertility and possibly sedimentary insulation, rather than high mantle temperature, account for the observed robust rift and post-rift magmatism.

The determination of melt distribution in the crust and the nature of the crust-mantle boundary (the 'Moho') is fundamental to the understanding of crustal accretion processes at oceanic spreading centres. Upper-crustal magma chambers have been imaged beneath fast- and intermediate-spreading centres but it has been difficult to image structures beneath these magma sills. Using three-dimensional seismic reflection images, here we report the presence of Moho reflections beneath a crustal magma chamber at the 9 degrees 03' N overlapping spreading centre, East Pacific Rise. Our observations highlight the formation of the Moho at zero-aged crust. Over a distance of less than 7 km along the ridge crest, a rapid increase in two-way travel time of seismic waves between the magma chamber and Moho reflections is observed, which we suggest is due to a melt anomaly in the lower crust. The amplitude versus offset variation of reflections from the magma chamber shows a coincident region of higher melt fraction overlying this anomalous region, supporting the conclusion of additional melt at depth.

The Earth's oceanic crust crystallizes from magmatic systems generated at mid-ocean ridges. Whereas a single magma body residing within the mid-crust is thought to be responsible for the generation of the upper oceanic crust, it remains unclear if the lower crust is formed from the same magma body, or if it mainly crystallizes from magma lenses located at the base of the crust. Thermal modelling, tomography, compliance and wide-angle seismic studies, supported by geological evidence, suggest the presence of gabbroic-melt accumulations within the Moho transition zone in the vicinity of fast- to intermediate-spreading centres. Until now, however, no reflection images have been obtained of such a structure within the Moho transition zone. Here we show images of groups of Moho transition zone reflection events that resulted from the analysis of approximately 1,500 km of multichannel seismic data collected across the intermediate-spreading-rate Juan de Fuca ridge. From our observations we suggest that gabbro lenses and melt accumulations embedded within dunite or residual mantle peridotite are the most probable cause for the observed reflectivity, thus providing support for the hypothesis that the crust is generated from multiple magma bodies.

Background: In the past decade, growth of coronary revascularization in Canada has been substantial. It was hypothesized that as coronary angiography (CA) rates increased, referral for necessary coronary artery bypass grafting (CABG) would also increase, and include patients with multivessel disease and class I to III angina who required elective surgery. Furthermore, it was proposed that the number of CABG surgeries needed would increase at a similar rate to that of CA., Methods: An incident cohort of patients who received CA in 1998/1999 was identified, and the group referred for CABG was followed. Clinical characteristics, appropriateness and necessity scores using specific criteria, and waiting times were evaluated and compared with a similar cohort from 1994/1995. Utilization data for coronary revascularization procedures from 1994 to 2002 were reviewed., Results: Between 1994/1995 and 1998/1999, the number of CAs per year increased by 37%. The inappropriateness rate for CA was 4% in 1998/1999. The proportion of patients diagnosed with critical coronary artery disease increased from 68% in 1994/1995 to 74% in 1998/1999. The number referred for CABG increased by 48%, and the number for percutaneous transluminal coronary angioplasty (PTCA) increased by 137%. The increase in the number referred for CABG was attributable to the increase in the number of patients with less severe symptoms who required delayed elective CABG. The necessity rate for CABG in the referred group was 94% in 1994/1995 and 95% in 1998/1999. A further 91 patients were identified who needed CABG but did not receive it, 86% of whom had PTCA. From 1999 to 2002, the annual growth rate in those referred for CABG was higher than the growth rate for CA., Conclusions: With the growth in CA, the rate of discovery of high risk coronary anatomy actually increased. Growth in CABG volume was attributable to growth in the need for elective surgery in patients with class I to III angina. The rate of CABG increased disproportionately to the rate of CA, despite higher rates of PTCA with stenting. It is likely that the demand for CABG will continue to rise steadily, as expansion of angiography occurs, and may be higher than expected from the growth in CA.

Background: Concentric and eccentric left ventricular hypertrophy are common progressive disorders in dialysis patients and are associated with cardiac failure and death. Although partial regression of these abnormalities is known to occur during the first post-transplant year, their long-term evolution is unknown., Methods: A total of 143 of 433 dialysis patients participating in a long-term prospective cohort study received renal transplants. Laboratory parameters were assessed monthly. Echocardiography was performed annually. Left ventricular mass index (LVMI) and cavity volume index were calculated according to standard formulae. Multiple linear regression was used to model change in LVMI as a function of baseline clinical and laboratory variables., Results: LVMI fell from 161 g/m2 at 1 year to 146 g/m2 (P=0.009) g/m2 after 2 years. No further regression was seen in years 3 and 4. Left ventricular volume index showed similar trends, with a decline from year 1 to year 2 (P=0.05) followed by stabilization in years 3 and 4. Older age, long duration of hypertension, need for more than one antihypertensive, high pulse pressure in normal-size hearts, and low pulse pressure in dilated hearts were significantly associated with failure of regression of LVMI between the first and second years (MLR, P<0.000001, r2=0.57)., Conclusions: Regression of left ventricular hypertrophy continues beyond the first year after renal transplantation, reaching a nadir at 2 years and persisting into the third and fourth posttransplant years. Failure to regress was associated with older age, hypertension, high pulse pressure in normal-size hearts and low pulse pressure in dilated hearts.

Quantifying the melt distribution and crustal structure across ridge-axis discontinuities is essential for understanding the relationship between magmatic, tectonic and petrologic segmentation of mid-ocean-ridge spreading centres. The geometry and continuity of magma bodies beneath features such as overlapping spreading centres can strongly influence the composition of erupted lavas and may give insight into the underlying pattern of mantle flow. Here we present three-dimensional images of seismic reflectivity beneath a mid-ocean ridge to investigate the nature of melt distribution across a ridge-axis discontinuity. Reflectivity slices through the 9 degrees 03' N overlapping spreading centre on East Pacific Rise suggest that it has a robust magma supply, with melt bodies underlying both limbs and ponding of melt beneath large areas of the overlap basin. The geometry of melt distribution beneath this offset is inconsistent with large-scale, crustal redistribution of melt away from centres of upwelling. The complex distribution of melt seems instead to be caused by a combination of vertical melt transport from the underlying mantle and subsequent focusing of melt beneath a magma freezing boundary in the mid-crust.

Background: Most comparisons of hemodialysis (HD) and peritoneal dialysis (PD) have used mortality as an outcome. Relatively few studies have directly compared the hospitalization rates, an outcome of perhaps equal importance, of patients using these different dialysis modalities., Methods: Eight hundred twenty-two consecutive patients at 11 Canadian institutions with irreversible renal failure had an extensive assessment of comorbid illness and initial mode of dialysis collected prospectively immediately prior to starting dialysis therapy. The cohort was assembled between March 1993 and November 1994. The mean follow-up was 24 months. Admission data were used to compare hospitalization rates in HD and PD., Results: Thirty-four percent of patients at baseline and 50% at three months used PD. Twenty-five percent of HD and 32% of PD patients switched dialysis modality at least once after their first treatment (P = NS). Nine percent of HD patients and 30% of PD patients switched modality after three months (P < 0. 001). Total comorbidity was higher in HD patients at baseline (P < 0. 001) and at three months (P = 0.001). The overall hospitalization rate was 40.2 days per 1000 patient days after baseline and 38.0 days per 1000 patient days after three months. When an adjustment was made for baseline comorbid conditions, patients on PD had a lower rate of hospitalization in intention-to-treat analysis according to the type of dialysis in use at baseline (RR 0.85, 95% CI, 0.82 to 0.87, P < 0.001), but a higher rate according to the type of dialysis in use three months after study entry (RR 1.31, 95% CI, 1.27 to 1.34, P < 0.001). In analyses based on the amount of time actually spent on each treatment modality, PD was associated with a higher rate of hospitalization when analyzed according to the type of dialysis in use at baseline (RR 1.10, 95% CI, 1.07 to 1.13, P < 0.001) and according to the type of dialysis in use three months after study entry (RR 1.26, 95% CI, 1.23 to 1.30, P < 0.001)., Conclusions: Conclusions regarding comparative hospitalization rates are heavily dependent on the analytic starting point and on whether intention-to-treat or treatment-received analyses are used. When early treatment switches are accounted for, HD is associated with a lower rate of hospitalization than PD, but the effect is modest.

Echocardiographic abnormalities are the rule in patients starting dialysis therapy and are associated with the development of cardiac failure and death. It is unknown, however, whether regression of these abnormalities is associated with an improvement in prognosis. As part of a prospective cohort study with mean follow-up of 41 mo, 227 patients had echocardiography at inception and after 1 yr of dialysis therapy. Improvements in left ventricular (LV) mass index, volume index, and fractional shortening were seen in 48, 48, and 46%, respectively. Ninety patients had developed cardiac failure by 1 yr of dialysis therapy. Twenty-six percent of the remaining 137 patients subsequently developed new-onset cardiac failure. The mean changes in LV mass index were 17 g/m(2) in those who subsequently developed cardiac failure compared with 0 g/m(2) among those who did not (P = 0.05). The corresponding values were -8 versus 0% for fractional shortening (P < 0.0001). The associations between serial change in both LV mass index and fractional shortening and subsequent cardiac failure persisted after adjusting for baseline age, diabetes, ischemic heart disease, and the corresponding baseline echocardiographic parameter. Regression of LV abnormalities is associated with an improved cardiac outcome in dialysis patients. Serial echocardiography adds prognostic information to one performed at baseline.

Background: Comparisons of mortality rates in patients on hemodialysis versus those on peritoneal dialysis have been inconsistent. We hypothesized that comorbidity has an important effect on differential survival in these two groups of patients., Methods: Eight hundred twenty-two consecutive patients at 11 Canadian institutions with irreversible renal failure had an extensive assessment of comorbid illness collected prospectively, immediately prior to starting dialysis therapy. The cohort was assembled between March 1993 and November 1994; vital status was ascertained as of January 1, 1998., Results: The mean follow-up was 24 months. Thirty-four percent of patients at baseline, 50% at three months, and 51% at six months used peritoneal dialysis. Values for a previously validated comorbidity score were higher for patients on hemodialysis at baseline (4.0 vs. 3.1, P < 0.001), three months (3.7 vs. 3.2, P = 0.001), and six months (3.6 vs. 3.2, P = 0.005). The overall mortality was 41%. The unadjusted peritoneal dialysis/hemodialysis mortality hazard ratios were 0.65 (95% CI, 0. 51 to 0.83, P = 0.0005), 0.84 (95% CI, 0.66 to 1.06, P = NS), and 0. 83 (95% CI, 0.64 to 1.08, P = NS) based on the modality of dialysis in use at baseline, three months, and six months, respectively. When adjusted for age, sex, diabetes, cardiac failure, myocardial infarction, peripheral vascular disease, malignancy, and acuity of renal failure, the corresponding hazard ratios were 0.79 (95% CI, 0. 62 to 1.01, P = NS), 1.00 (95% CI, 0.78 to 1.28, P = NS), and 0.95 (95% CI, 0.73 to 1.24, P = NS). Adjustment for a previously validated comorbidity score resulted in hazard ratios of 0.74 (95% CI, 0.58 to 0.94, P = 0.01), 0.94 (95% CI, 0.74 to 1.19, P = NS), and 0.88 (95% CI, 0.68 to 1.13, P = NS) at baseline, three months, and six months. There was no survival advantage for either modality in any of the major subgroups defined by age, sex, or diabetic status., Conclusions: The apparent survival advantage of peritoneal dialysis in Canada is due to lower comorbidity and a lower burden of acute onset end-stage renal disease at the inception of dialysis therapy. Hemodialysis and peritoneal dialysis, as practiced in Canada in the 1990s, are associated with similar overall survival rates.

Objective: To demonstrate that manipulation under anesthesia (MUA), a conservative treatment modality, is both safe and efficacious in the treatment of both acute and chronic spinal pain disorders in appropriately selected patients. MUA can be safely used to treat pain arising from the cranial, cervical, thoracic, and lumbar spine, as well as the sacroiliac and pelvic region., Setting: An ambulatory surgical center., Subjects: The treatment group consisted of 177 patients between ages 17 and 65 years. Evaluation followed a treatment algorithm created by the authors as a multidisciplinary approach to patient selection, evaluation, treatment, and timing of specialized referral, in consideration of previously published algorithms. Prior forms of treatment, both conservative and surgical in nature, had failed in these patients., Intervention: Patients underwent three sequential manipulations under intravenous sedation, followed by 4 to 6 weeks of skilled spinal manipulation and therapeutic modalities., Outcome Measures: Data regarding changes in Visual Analog Scale (VAS), range of motion, medication needs, and return to work status were used to document progress. All patients had follow-up for 6 months., Results: On average, VAS ratings improved by 62.2% in those patients with cervical pain problems. On average, VAS ratings improved by 60.1% in those patients with lumbar pain problems. There was a near-complete reversal in patients out of work before MUA (68.6%) and those returning to unrestricted activities at 6 months after MUA (64.1%). There was a 58.4% reduction in the percentage of patients requiring prescription pain medication from the pre-MUA period to 6 months after MUA. Additionally, 24.0% of the treatment group required no medication at 6 months after MUA., Conclusion: A multidisciplinary approach to evaluation and treatment, including MUA, offers patient benefits above and beyond what can be obtained through the individual providers working alone.

Background: Left ventricular enlargement is very common at the inception of dialysis therapy, and highly predictive of future cardiac morbidity and mortality. It is not known whether cardiac size increases further while on dialysis therapy and whether potentially reversible risk factors for later progression can be identified. METHODS; Baseline and yearly echocardiograms were performed in a prospective inception cohort of 433 dialysis patients. The mean patient follow-up was 41 months; 29 patients had four consecutive echocardiograms at yearly intervals., Results: The patient subset with four echocardiograms was older (58 vs. 51 years, P = 0.02) and had a lower mass ventricular mass index (128 vs. 149 g/m2, P = 0.02) than the parent group. Using repeated measures analysis of variance, applied to those with four echocardiograms, there were progressive increases over time in posterior wall thickness (P = 0.015), left ventricular end-diastolic diameter, left ventricular mass index (P = 0.001), and cavity volume index (P = 0. 001). Mass-to-volume ratios did not change. The biggest changes in mass (18 g/m2 - 14%)and volume index (13 ml/m2 - 18%) occurred between baseline and year 1, although increases in both were seen after year 1. Hemodialysis versus peritoneal dialysis (41 g/m2, P = 0.008) and anemia (10 g/m2 per 1 g/dl drop in hemoglobin, P = 0.02) were associated with progressive left ventricular enlargement, but only within the first year of dialysis therapy. The left ventricular enlargement seen after year 1 was independent of anemia, blood pressure, serum albumin and mode of dialysis., Conclusions: Progressive cardiac enlargement, particularly left ventricular dilation with compensatory hypertrophy, continues after starting dialysis therapy. Most of the additional cardiac enlargement seems to occur in the first year of dialysis therapy, suggesting that intervention beyond one year may be relatively ineffective.

Despite considerable differences in technique and blood purification characteristics, hemodialysis and peritoneal dialysis have been thought to have similar patient outcomes. An inception cohort of 433 end-stage renal disease patients was followed prospectively for a mean of 41 mo. The outcomes of hemodialysis (HD) and peritoneal dialysis (PD) patients were compared using intention to treat analysis based on the mode of therapy at 3 mo. After adjustment for PD patients less likely to have chronic hypertension and more likely to have diabetes, ischemic heart disease, and cardiac failure at baseline (P < 0.05), a biphasic mortality pattern was observed. For the first 2 yr, there was no statistically significant difference in mortality. After 2 yr, mortality was greater among PD patients with an adjusted PD/HD hazard ratio of 1.57 (95% confidence interval [CI], 0.97 to 2.53). Both the occurrence (adjusted hazards ratio 6.87 [95% CI, 2.01 to 23.5]) and the direction (toward PD, adjusted hazards ratio 6.25 [95% CI, 1.54 to 25]) of a therapy switch were subsequently associated with mortality after 2 yr. Progressive clinical and echocardiographic cardiac disease were not responsible for this late mortality. Lower mean serum albumin levels in PD patients in the first 2 yr of therapy (3.5 +/- 0.5 versus 3.9 +/- 0.5 g/dl, P < 0.0001) accounted for a large proportion of the increase in subsequent mortality. Hemodialysis has a late survival advantage over peritoneal dialysis; antecedent hypoalbuminemia is a major marker of the increased late mortality in PD patients.

Little is known about the epidemiology of cardiac disease in diabetic end-stage renal disease. We therefore prospectively followed a cohort of 433 patients who survived 6 months after the inception of dialysis therapy for an average of 41 months. Clinical and echocardiographic data were collected yearly. At baseline, diabetic patients (n = 116) had more echocardiographic concentric left ventricular hypertrophy (50 vs 38%, p = 0.04), clinically diagnosed ischaemic heart disease (32 vs 18%, p = 0.003) and cardiac failure (48 vs 24%, p < 0.00001) than non-diabetic patients (n = 317). After adjusting for age and sex, diabetic patients had similar rates of progression of echocardiographic disorders, and de novo cardiac failure, but higher rates of de novo clinically diagnosed ischaemic heart disease (RR 3.2, p = 0.0002), overall mortality (RR 2.3, p < 0.0001) and cardiovascular mortality (RR 2.6, p < 0.0001) than non-diabetic patients. Mortality was higher in diabetic patients following admission for clinically diagnosed ischaemic heart disease (RR 1.7, p = 0.05) and cardiac failure (RR 2.2, p = 0.0003). Among diabetic patients older age, left ventricular hypertrophy, smoking, clinically diagnosed ischaemic heart disease, cardiac failure and hypoalbuminaemia were independently associated with mortality. The excessive cardiac morbidity and mortality of diabetic patients seem to be mediated via ischaemic disease, rather than progression of cardiomyopathy while on dialysis therapy. Potentially remediable risk factors include smoking, left ventricular hypertrophy, and hypoalbuminaemia.

To determine the possible association between anemia and clinical and echocardiographic cardiac disease, a cohort of 432 end-stage renal disease patients (261 on hemodialysis and 171 on peritoneal dialysis) who started dialysis therapy between 1982 and 1991 were followed prospectively for an average of 41 months. Baseline demographic, clinical, and echocardiographic assessments were performed, as well as monthly serial clinical and laboratory tests while the patients were on dialysis therapy. The mean (+/-SD) hemoglobin level during dialysis therapy was 8.8 +/- 1.5 g/dL. After adjusting for age, diabetes, and ischemic heart disease, as well as for blood pressure and serum albumin levels measured serially, each 1 g/dL decrease in mean hemoglobin was independently associated with the presence of left ventricular dilatation on repeat echocardiogram (odds ratio, 1.46; P = 0.018) and the development of de novo (relative risk [RR] = 1.28; P = 0.018) and recurrent (RR = 1.20; P = 0.046) cardiac failure. In addition, each 1 g/dL decrease in the mean hemoglobin level was independently associated with mortality while the patients were on dialysis therapy (RR = 1.14; P = 0.024). Anemia had no independent association with the development of ischemic heart disease while the patients were on dialysis therapy. Anemia, an easily reversible feature of end-stage renal disease, is an independent risk factor for clinical and echocardiographic cardiac disease, as well as mortality in end-stage renal disease patients.

Background: Left ventricular disease occurs frequently in dialysis patients. It may be manifest as concentric LV hypertrophy, LV dilatation with or without LV hypertrophy, or systolic dysfunction. Little is known concerning the clinical outcome and risk factors for these disorders., Methods: A cohort of 432 end-stage renal disease patients who survived at least 6 months had an echocardiogram on initiation of dialysis therapy. Clinical, laboratory and echocardiographic data was obtained annually during follow-up., Results: On initiation of ESRD therapy 16% of patients had systolic dysfunction, 41% concentric LV hypertrophy, 28% LV dilatation, and only 16% had normal echocardiograms. Median time to development of heart failure was 19 months in patients with systolic dysfunction, 38 months in concentric LV hypertrophy and 38 months in LV dilatation. The relative risks of heart failure in the three groups were significantly worse than in the normal group, after adjusting for age, diabetes and ischaemic heart disease. Median survival was 38 months in systolic dysfunction, 48 months in concentric hypertrophy, 56 months in LV dilatation, and >66 months in the normal group. Two hundred and seventy-five patients had a follow-up echocardiogram 17 months after starting dialysis therapy together with serial measurement of potential risk factors prior to the echocardiogram. On follow-up echocardiogram the degree of concentric LV hypertrophy was independently related to hypertension while on dialysis, older age, and anaemia while on dialysis; the degree of LV dilatation was related to ischaemic heart disease, anaemia, hypertension and hypoalbuminemia while on dialysis; the degree of systolic dysfunction was associated with ischaemic heart disease and anaemia during follow-up., Conclusions: Manifestations of left ventricular disease are frequent and persistent in chronic uraemia, and are associated with high risks of heart failure and death. Potentially reversible risk factors include anaemia, hypertension, hypoalbuminaemia and ischaemic heart disease.

To determine the prognosis and risk factors for ischemic heart disease in chronic uremia, a cohort of 432 dialysis patients were followed prospectively from start of dialysis therapy until death or renal transplantation. Baseline demographic, clinical and echocardiographic data were obtained. After the initiation of dialysis laboratory data were collected at monthly intervals, and clinical and echocardiographic data at yearly intervals. Twenty-two percent of patients (N = 95) had either a history of angina pectoris or myocardial infarction on starting dialysis therapy. Median time to onset of heart failure was 24 months in those with ischemic heart disease on initiation of dialysis, compared to 55 months in those without (P < 0.0001). This effect was independent of age, diabetes and underlying cardiomyopathy. Median survival was 44 months in those with ischemic disease compared to 56 months in those without (P = 0.0001). This adverse impact was independent of age and diabetes mellitus but, when cardiac failure was added to the Cox's model, ischemic heart disease was no longer an independent predictor of survival. De novo ischemic heart disease, not evident on starting dialysis therapy, occurred in 41 (9%) patients. When compared to patients who never developed ischemic disease (N = 296; 69%), significant and independent predictors of de novo disease were older age (P = 0.0007), diabetes mellitus (P = 0.0001), high blood pressure during follow up on dialysis (P = 0.02) and hypoalbuminemia (P = 0.03), whereas anemia was not an independent predictor. LV mass index was 174 +/- 7 g/m2 in those who developed de novo ischemic disease compared to 155 +/- 3 g/m2 (P < 0.001) in those who did not. Concentric LV hypertrophy, LV dilation and systolic dysfunction were independent risk factors for de novo ischemic heart disease. We conclude that ischemic heart disease occurs frequently in dialysis patients, that its adverse impact is mediated through the development of heart failure, and that the most important, potentially reversible risk factors are hypertension, hypoalbuminemia, and underlying cardiomyopathy.

A cohort of 432 ESRD (261 hemodialysis and 171 peritoneal dialysis) patients was followed up prospectively for an average of 41 months. Baseline and annual demographic, clinical, and echocardiographic assessments were performed, as well as serial clinical and laboratory tests measured monthly while patients were on dialysis therapy. Among hemodialysis patients, after adjustment was made for age, diabetes, and ischemic heart disease, as well as hemoglobin and blood pressure levels measured serially, a 10-g/L fall in mean serum albumin level was independently associated with the the development of de novo (relative risk [RR], 2.22; P = 0.001) and recurrent cardiac failure (RR, 3.84; P = 0.003), de novo (RR, 5.29; P = 0.001) and recurrent ischemic heart disease (RR, 4.24; P = 0.005), cardiac mortality (RR, 5.60; P = 0.001), and overall mortality (RR, 4.33; P < 0.001). Among peritoneal dialysis patients, a 10-g/L fall in mean serum albumin level was independently associated with the progression of left ventricular dilation as seen on follow-up echocardiography (beta, 13.4 mL/m2; P = 0.014), the development of de novo cardiac failure (RR, 4.16; P = 0.003), and overall mortality (RR, 2.06; P < 0.001). Hypoalbuminemia, a major adverse prognostic factor in dialysis patients, is strongly associated with cardiac disease.

A cohort of 432 ESRD (261 hemodialysis and 171 peritoneal dialysis) patients was followed prospectively for an average of 41 months. Baseline and annual demographic, clinical and echocardiographic assessments were performed, as well as serial clinical and laboratory tests measured monthly while on dialysis therapy. The average mean arterial blood pressure level during dialysis therapy was 101 +/- 11 mm Hg. After adjusting for age, diabetes and ischemic heart disease, as well as hemoglobin and serum albumin levels measured serially, each 10 mm Hg rise in mean arterial blood pressure was independently associated with: the presence of concentric LV hypertrophy (OR 1.48, P = 0.02), the change in LV mass index (beta = 5.4 g/m2, P = 0.027) and cavity volume (beta = 4.3 ml/m2, P = 0.048) on follow-up echocardiography, the development of de novo cardiac failure (RR 1.44, P = 0.007), and the development of de novo ischemic heart disease (RR 1.39, P = 0.05). The association with LV dilation was of borderline statistical significance (OR 1.48, P = 0.06). Mean arterial blood pressures greater than 106 mm Hg were associated with both echocardiographic and clinical endpoints. Paradoxically, low mean arterial blood pressure (RR 1.36 per 10 mm Hg fall, P = 0.009) was independently associated with mortality. The association of low blood pressure with mortality was a marker for having had cardiac failure prior to death. We conclude that even moderate hypertension worsens the echocardiographic and clinical outcome in ESRD patients, especially in those without previous clinical cardiac disease.

Background: Hypocalcemia and hyperphosphatemia with secondary hyper-parathyroidism are characteristic of end-stage renal disease (ESRD). Although calcium levels critically affect almost all cellular processes, the impact of chronic hypocalcemia and other abnormalities of calcium-phosphate homeostasis on the prognosis of ESRD patients is unknown., Methods: An inception cohort of 433 patients starting ESRD therapy was followed prospectively for an average of 41 months. Serum calcium and other parameters were measured monthly. The mean calcium levels were 9.4 +/- 0.7 mg/dl. 23% of the patients had mean calcium levels < 8.8 mg/dl. After adjusting for baseline age, diabetes mellitus, ischemic heart disease, smoking and cholesterol levels, as well as serial albumin, hemoglobin, mean arterial blood pressure, phosphate and alkaline phosphatase levels, chronic hypocalcemia was strongly associated with mortality (RR 2.10, p = 0.006 for a mean calcium level < 8.8 mg/dl). The association with mortality was similar in hemodialysis (RR 2.10, p = 0.006) and peritoneal dialysis patients (2.67, p = 0.034). Using similar covariate adjustment, chronic hypocalcemia was associated with de novo ischemic heart disease (RR 5.23, p < 0.001), recurrent ischemic heart disease (RR 2.46, p = 0.006), de novo cardiac failure (RR 2.64, p < 0.001), and recurrent cardiac failure (RR 3.30, p < 0.001). Hypocalcemia retained its independent impact on morbidity and mortality when analyzed as a time-dependent covariate., Conclusions: Chronic hypocalcemia, a very common, reversible feature of chronic uremia, is independently associated with morbidity and mortality in ESRD patients.

In chronic uremia, cardiomyopathy manifests itself as systolic dysfunction, concentric left ventricular (LV) hypertrophy, or LV dilatation. To determine the impact of renal transplantation on uremic cardiomyopathy, all dialysis patients participating in a long-term cohort study who received a successful renal transplant were followed with echocardiography. The transplanted group comprised 102 of 433 (24%) endstage renal disease (ESRD) patients. They were significantly younger and, on starting ESRD therapy, had significantly less ischemic heart disease and cardiac failure than the overall ESRD cohort. During followup, ischemic heart disease developed in only 1 patient and none experienced cardiac failure. In the 12% (n = 12) of patients with systolic dysfunction before renal transplant, fractional shortening normalized in all patients, increasing from 21.5 +/- 4.6% to 33.5 +/- 5.6% after transplantation. In the 41% (n = 41) with concentric LV hypertrophy before transplantation, the LV mass index improved from 158 +/- 39 g/m2 to 132 +/- 39 g/m2. LV dilatation was present in 32% (n = 32) of patients before transplantation. After transplantation, LV volume fell from 116 +/- 3.1 ml/m2 to 89 +/- 21 ml/m2, and LV mass index in this group fell from 166 +/- 55 g/m2 to 135 +/- 37 g/m2. It was not possible to associate risk factors characteristic of the uremic state with the improvement in cardiac structure and function, although the fall in LV mass was significantly associated with fall in blood pressure. We conclude that correction of the uremic state by renal transplantation leads to normalization of LV contractility in systolic dysfunction, regression of hypertrophy in concentric LV hypertrophy, and improvement of cavity volume in LV dilatation. The degree of improvement suggests that dialysis patients with uremic cardiomyopathy would benefit from renal transplantation.

The objective of this study was to determine the effect of left ventricular (LV) mass, volume, and mass-to-volume ratio on mortality in chronic dialysis patients. The Design was a multicenter, prospective inception cohort study with a median follow-up of 41 months. The Setting was three university-affiliated nephrology units. A total of 433 patients who (1) survived > 6 months from the start of ESRD therapy and (2) had a technically satisfactory baseline echocardiogram were studied. Measurements included a baseline clinical, laboratory and echocardiographic assessment. LV hypertrophy was present in 74% and LV dilation was present in 36% of patients. In patients with normal cavity volume (< or = 90 mL/m2) and normal systolic function, high LV mass index (> 120 g/m2) and mass-to-volume ratios (> 2.2 g/mL) were independently associated with late mortality (> 2 yr after starting dialysis therapy). After adjusting for baseline age, diabetes, and ischemic heart disease, the relative risk for the former was 3.29 and for the latter was 2.24. Cavity volume was of no prognostic significance in this group. In patients with LV dilation and normal systolic function, high cavity volume (> 120 mL/m2) and low mass-to-volume ratio (< 1.8 mL/m2) were independently associated with late mortality, the relative risk in the former being 17.14 and the latter being 4.27. LV mass index was of no prognostic significance in this group. The baseline echocardiographic classification, based on LV mass and cavity volume, was the strongest predictor of late mortality, after adjusting for age, gender, diabetes mellitus, coronary artery disease, angina pectoris, chronic hypertension, and hemoglobin and serum albumin levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Seismic reflection data from the East Pacific Rise between 17 degrees 05' and 17 degrees 35'S image a magma lens that varies regularly in depth and width as ridge morphology changes, confirming the notion that axial morphology can be used to infer ridge magmatic state. However, at 17 degrees 26'S, where the ridge is locally shallow and broad, the magma lens is markedly shallower and wider than predicted from regional trends. In this area, submersible dives reveal recent volcanic eruptions. These observations indicate that it is where the width and depth of the magma chamber differ from regional trends, indicating an enhanced magmatic budget, that is diagnostic of current magmatism.

Patients on dialysis have an age-adjusted death rate 3.5 times that of the general population. The most common cause of death in patients on dialysis is cardiovascular disease. We prospectively followed a cohort of 433 patients in three centers for a mean of 41 months. Mean hemoglobin level at the beginning of dialysis was 8.39 (+/- 1.7) g/dL, and the mean hemoglobin level during follow-up was 8.84 (+/- 1.5) g/dL. Using Cox's regression model, we found that anemia predicted mortality independently of age, diabetes mellitus, cardiac failure, hypoalbuminemia, serum creatinine, mean arterial pressure, or echocardiographic heart disease. The independent relative risk (RR) of mortality was 1.18 per 1.0 g/dL decrease in hemoglobin level. Anemia also independently predicted the de novo occurrence of congestive heart failure when the same covariates were controlled for (RR, 1.49 per 1.0 g/dL decrease). Anemia was also independently predictive of heart failure at the start of dialysis (RR, 1.14 per 1.0 g/dL decrease) and heart failure recurrence (RR, 1.25 per 1.0 g/dL decrease). Left ventricular hypertrophy is present in 75% of patients on dialysis at the start of therapy for end-stage renal disease. It independently predicts mortality. Our prospective cohort study identified increasing age, hypertension, and anemia as risk factors for its development. One controlled study and several uncontrolled studies demonstrated improvement (but not complete regression) of elevated left ventricular mass in patients on dialysis treated with recombinant human erythropoietin (epoetin).

Cardiovascular disease is the most common cause of death in dialysis subjects. Congestive heart failure (CHF) is a common presenting symptom of cardiovascular disease in the dialysis population. Information regarding prevalence, incidence, risk factors and prognosis is crucial for planning rational interventional studies. A prospective multicenter cohort study of 432 dialysis patients followed for a mean of 41 months was carried out. Prospective information on a variety of risk factors was collected. Annual echocardiography and clinical assessment was performed. Major endpoints included death and the development of morbid cardiovascular events. One hundred and thirty-three (31%) subjects had CHF at the time of initiation of dialysis therapy. Multivariate analysis showed that the following risk factors were significantly and independently associated with CHF at baseline: systolic dysfunction, older age, diabetes mellitus and ischemic heart disease. Seventy-six of 299 subjects (25%) who did not have baseline CHF subsequently developed CHF during their course on dialysis. Compared to those subjects who never developed CHF (N = 218) multivariate analysis identified the following risk factors for the development of CHF: older age, anemia during dialysis therapy, hypoalbuminemia, hypertension during dialysis therapy, and systolic dysfunction. Seventy-five of the 133 (56%) subjects with CHF at baseline had recurrent CHF during follow-up. Independent and significant risk factors for CHF recurrence were ischemic heart disease and systolic dysfunction, anemia during dialysis therapy and hypoalbuminemia. The median survival of subjects with CHF at baseline was 36 months compared to 62 months in subjects without CHF. In this study the prevalence of CHF on starting ESRD therapy and the subsequent annual incidence was high.(ABSTRACT TRUNCATED AT 250 WORDS)

End-stage renal disease (ESRD) patients have a high cardiovascular mortality rate. Precise estimates of the prevalence, risk factors and prognosis of different manifestations of cardiac disease are unavailable. In this study a prospective cohort of 433 ESRD patients was followed from the start of ESRD therapy for a mean of 41 months. Baseline clinical assessment and echocardiography were performed on all patients. The major outcome measure was death while on dialysis therapy. Clinical manifestations of cardiovascular disease were highly prevalent at the start of ESRD therapy: 14% had coronary artery disease, 19% angina pectoris, 31% cardiac failure, 7% dysrhythmia and 8% peripheral vascular disease. On echocardiography 15% had systolic dysfunction, 32% left ventricular dilatation and 74% left ventricular hypertrophy. The overall median survival time was 50 months. Age, diabetes mellitus, cardiac failure, peripheral vascular disease and systolic dysfunction independently predicted death in all time frames. Coronary artery disease was associated with a worse prognosis in patients with cardiac failure at baseline. High left ventricular cavity volume and mass index were independently associated with death after two years. The independent associations of the different echocardiographic abnormalities were: systolic dysfunction-older age and coronary artery disease; left ventricular dilatation-male gender, anemia, hypocalcemia and hyperphosphatemia; left ventricular hypertrophy-older age, female gender, wide arterial pulse pressure, low blood urea and hypoalbuminemia. We conclude that clinical and echocardiographic cardiovascular disease are already present in a very high proportion of patients starting ESRD therapy and are independent mortality factors.

The objective of this study was to determine the role of hypertension, age, anemia, and hyperparathyroidism in the pathogenesis of left ventricular hypertrophy (LVH) developing after the initiation of dialysis for ESRD. A cohort of dialysis patients who were being treated for ESRD and whose initial echocardiograms after the start of dialysis therapy do not show LVH were studied. Three hundred and thirty-nine patients have been monitored at three centers since 1985. Serial echocardiograms have been performed with M-mode and two-dimensional echocardiography. Data on blood pressure, height, weight, hemoglobin, number and type of antihypertensive medications, and the presence of functioning vascular access have been collected prospectively. Prospective data on serum calcium, serum phosphorus, alkaline phosphatase, and parathyroid hormone levels and skeletal x-rays have also been collected. By the use of set criteria and blinding to echocardiographic outcome, the presence and severity of hyperparathyroidism were graded by consensus. Fifty-one patients met eligibility criteria for inclusion; of these, 14 developed LVH (cases) and 37 did not (controls). Cases had significantly higher systolic blood pressure (P = 0.009) and were older (P = 0.01) than controls. Systolic blood pressure correlated significantly with final posterior left ventricular wall thickness (r = 0.39; P < 0.01). By the use of multivariate analysis, age and systolic blood pressure were significantly and independently associated with increased left ventricular mass index. The frequency of hyperparathyroidism was low and equal in both groups. There was a trend toward more severe anemia in cases that did not reach statistical significance.(ABSTRACT TRUNCATED AT 250 WORDS)

Seismic data from the ultrafast-spreading (150 to 162 millimeters per year) southern East Pacific Rise show that the rise axis is underlain by a thin (less than 200 meters thick) extrusive volcanic layer (seismic layer 2A) that thickens rapidly off axis. Also beneath the rise axis is a narrow (less than 1 kilometer wide) melt sill that is in some places less than 1000 meters below the sea floor. The small dimensions of this molten body indicate that magma chamber size does not depend strongly on spreading rate as predicted by many ridge-crest thermal models. However, the shallow depth of this body is consistent with an inverse correlation between magma chamber depth and spreading rate. These observations indicate that the paradigm of ridge crest magma chambers as small, sill-like, midcrustal bodies is applicable to a wide range of intermediate- and fast-spreading ridges.

In an attempt to gain information that could be directly applied to the design of clinical porous-surfaced prostheses intended for biological attachment by bone ingrowth, the tensile strength of the bone-implant interface was expressed as a function of 2 fundamentally different porous-surface configurations. Using powder metallurgy techniques, standard 3-hole fracture fixation plates were prepared with both a single and a multiple layer of spherically shaped metal powder particles on the bone-contacting surface to produce implants with different porous surfaces. These plates were implanted onto the lateral aspect of canine femurs for periods of 4, 6, 8, 12, 18, and 24 weeks. Mechanical tests were performed to measure the tensile strength of fixation of the implants by the ingrowth of bone. The results of the mechanical tests indicated that implants with the multiple particle layer surfce configuration develop a greater tensile strength of fixation than do implants with the single particle layer surface configuration. In addition, this fixation strength develops more quickly if the cortical bone is petaled prior to implantation. These findings should be considered when designing porous-surfaced implants intended for fixation by bone ingrowth.

Clinical experience indicates that the risk of reparative cardiac operations is increased in the neonatal period relative to that in older infants and children. Age-related differences in the susceptibility to myocardial ischemic dysfunction were evaluated by comparison of left ventricular function and metabolism in neonatal (mean age = 7 days) and weanling (mean age = 96 days) piglets. Six animals in each group supported on cardiopulmonary bypass were subjected to (1) 120 minutes of hypothermic crystalloid cardioplegic arrest (CP-120) and (2) 15 minutes of normothermic ischemic arrest (NA-15) after a 60 minute interval of reperfusion. Left ventricular systolic and diastolic function was measured after each intervention via endocardially implanted ultrasonic dimension crystals in a septolateral minor-axis position. In both groups, systolic dysfunction was evidenced by an increase in the dimension-axis intercept (p = 0.001), but not the slope of the end-systolic pressure-dimension relation. Left ventricular end-diastolic stiffness, expressed as left ventricular end-diastolic pressure versus Lagrangian strain, increased to a similar degree in both groups (p = 0.001). Adenosine triphosphate levels declined significantly (p = 0.001) in both groups in response to the ischemic interventions with no evident intergroup differences. Lactate levels increased significantly during the course of the experiment (p = 0.04); however, the increases were greater (p = 0.009) at all intervals in the neonatal group. This study demonstrates age-related metabolic differences in response to ischemia consistent with a greater dependence on glycolysis in neonatal myocardia. However, the fact that discriminating age-related differences in left ventricular function were not evident suggests that factors other than young age per se account for the increased surgical mortality in the neonatal period.

We have perfused malignant hyperthermia susceptible and normal isolated pig livers with halothane for one hour. The liver temperatures, oxygen and carbon dioxide tensions, the base deficits and lactate concentrations in blood entering and leaving the liver have been measured at the beginning and at the end of the perfusion. Statistical analysis has shown that there are no significant differences in these parameters between the beginning and the end of the perfusion period or between the normal and the malignant hyperthermia susceptible livers. We conclude, therefore, that the livers of malignant hyperthermia susceptible pigs are either normal or else, if abnormal, the abnormalities are sufficiently benign as to be not measurably expressed.