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Introduction /Objectives: The objectives were to conduct a survey of cardiologists on their recent experiences with cats that have dilated cardiomyopathy (DCM), and to retrospectively review individual cases of feline DCM. Animals, Materials and Methods Part One: A survey was distributed to cardiologists with questions regarding caseload and clinical management of cats with DCM diagnosed over the past two years. Part Two: Cardiologists completing the survey were invited to submit data from cats recently diagnosed with DCM. Data on signalment, clinical signs, diet, echocardiographic measurements, and outcome were recorded. Results Part One: From 52 completed surveys, many cardiologists responded that measuring and supplementing taurine and recommending a diet change in cats with DCM are common practices. Few (15%) cardiologists reported an increase in number of feline DCM cases over the past two years, although some had cases that improved even if taurine deficiency was not present. Part Two: Twenty of 37 (54%) cats ate low pea/lentil (low PL) diets and 14/37 (38%) ate high pea/lentil (high PL) diets at the time of diagnosis; three had incomplete diet information. Two of 13 cats (15%) in which taurine was measured had levels below the reference range. After adjusting for other variables, cats eating high PL diets that changed diets post-diagnosis had a significantly longer survival time compared to cats eating high PL diets that did not change diets post-diagnosis (P=0.025). Conclusions Additional research is warranted to determine whether there could be a possible association between diet and DCM in cats.

OBJECTIVE To evaluate whether mesenchymal stem cells (MSCs) can be safely administered IV to dogs with congestive heart failure (CHF) secondary to myxomatous mitral valve disease (MMVD) to improve cardiac function and prolong survival time. ANIMALS 10 client-owned dogs with CHF secondary to MMVD. PROCEDURES Dogs with an initial episode of CHF secondary to MMVD were enrolled in a double-blind, placebo-controlled clinical trial. Five dogs in the MSC group received allogeneic Wharton jelly–derived MSCs (2 X 106 cells/kg, IV), and 5 dogs in the placebo group received a 1% solution of autologous serum (IV) for 3 injections 3 weeks apart. Cell-release criteria included trilineage differentiation, expression of CD44 and CD90 and not CD34 and major histocompatability complex class II, normal karyotype, and absence of contamination by pathogenic microorganisms. Patients were followed for 6 months or until death or euthanasia. Echocardiographic data, ECG findings, serum cardiac biomarker concentrations, CBC, and serum biochemical analysis results were obtained prior to and 4 hours after the first injection and every 3 months after the final injection. RESULTS Lymphocyte and eosinophil counts decreased significantly 4 hours after injection, and monocytes decreased significantly only in dogs that received an MSC injection. No significant differences were seen in the echocardiographic variables, ECG results, serum cardiac biomarker concentrations, survival time, and time to first diuretic drug dosage escalation between the 2 groups. CONCLUSIONS AND CLINICAL RELEVANCE This study showed that MSCs can be easily collected from canine Wharton jelly as an allogeneic source of MSCs and can be safely delivered IV to dogs with CHF secondary to MMVD.

Background The United States Food and Drug Administration is investigating possible diet‐associated dilated cardiomyopathy (DCM) in dogs and cats. Objectives To retrospectively review DCM cases for signalment, diet information, echocardiographic changes, and survival. Animals Client‐owned dogs (n = 71). Methods Medical records of dogs diagnosed with DCM between January 1, 2014 and September 30, 2018 were reviewed. Dogs were grouped into “traditional” or “nontraditional” diet categories and whether or not diet was changed after diagnosis. Results For dogs eating nontraditional diets, those that had their diets changed had a larger percentage decrease in normalized systolic left ventricular internal dimension (P = .03) and left atrial:aorta ratio (P

PURPOSE OF REVIEW: While vascular endothelial growth factor receptor inhibitors (VEGFRis) have dramatically improved cancer survival, these drugs cause hypertension in a majority of patients. This side effect is often dose limiting and increases cardiovascular mortality in cancer survivors. This review summarizes recent advances in our understanding of the molecular mechanisms and clinical findings that impact management of VEGFRi-induced hypertension. RECENT FINDINGS: Recent studies define new connections between endothelial dysfunction and VEGFRi-induced hypertension, including the balance between nitric oxide, oxidative stress, endothelin signaling, and prostaglandins and the potential role of microparticles, vascular smooth muscle cells, vascular stiffness, and microvessel rarefaction. Data implicating genetic polymorphisms that might identify patients at risk for VEGFRi-induced hypertension and the growing body of literature associating VEGFRi-induced hypertension with antitumor efficacy are reviewed. SUMMARY: These recent advances have implications for the future of cardio-oncology clinics and the management of VEGFRi-induced hypertension.

Chemotherapy-induced impairment of autophagy is implicated in cardiac toxicity induced by anti-cancer drugs. Imperfect translation from rodent models and lack of in vitro models of toxicity has limited investigation of autophagic flux dysregulation, preventing design of novel cardioprotective strategies based on autophagy control. Development of an adult heart tissue culture technique from a translational model will improve investigation of cardiac toxicity. We aimed to optimize a canine cardiac slice culture system for exploration of cancer therapy impact on intact cardiac tissue, creating a translatable model that maintains autophagy in culture and is amenable to autophagy modulation. Canine cardiac tissue slices (350 μm) were generated from left ventricular free wall collected from euthanized client-owned dogs (n = 7) free of cardiovascular disease at the Foster Hospital for Small Animals at Tufts University. Cell viability and apoptosis were quantified with MTT assay and TUNEL staining. Cardiac slices were challenged with doxorubicin and an autophagy activator (rapamycin) or inhibitor (chloroquine). Autophagic flux components (LC3, p62) were quantified by western blot. Cardiac slices retained high cell viability for >7 days in culture and basal levels of autophagic markers remained unchanged. Doxorubicin treatment resulted in perturbation of the autophagic flux and cell death, while rapamycin co-treatment restored normal autophagic flux and maintained cell survival. We developed an adult canine cardiac slice culture system appropriate for studying the effects of autophagic flux that may be applicable to drug toxicity evaluations.

Objectives Growth differentiation factor (GDF) 11 has been shown to reduce cardiac hypertrophy in mice. Low levels of GDF-11 are associated with cardiac hypertrophy in humans. The authors hypothesized that plasma GDF-11 level is decreased in cats with hypertrophic cardiomyopathy (HCM). Given the close homology between GDF-11 and myostatin/GDF-8, GDF-8 levels were also assessed. Animals Thirty-seven client-owned cats were enrolled, including cats with normal cardiac structure (n = 16), cats with HCM or hypertrophic obstructive cardiomyopathy (HOCM; n = 14), and cats with HCM and congestive heart failure (CHF; n = 7). Methods Plasma samples were analyzed for GDF-8 and GDF-11 using liquid chromatography tandem-mass spectrometry. Levels of GDF-8 and GDF-11 were compared between cats with normal cardiac structure, HCM or HOCM, and CHF. Results No differences in GDF-11 concentrations were found between cats with normal cardiac structure and cats with HCM/HOCM, with or without history of CHF. Decreased GDF-8 concentrations were detected in cats with CHF compared to cats with HCM/HOCM without history of CHF (p=0.031) and cats with normal cardiac structure (p=0.027). Growth differentiation factor 8 was higher in cats with HOCM compared to those with CHF (p=0.002). No statistical difference was noted in GDF-8 level as a function of age, weight, or body condition score. Conclusions Plasma GDF-11 was not different between cats with HCM/HOCM and cats with normal cardiac structure regardless of age. Plasma GDF-8 was decreased in cats with CHF compared to cats with normal cardiac structure and cats with asymptomatic HCM/HOCM, suggesting a possible role in CHF development.

Dogs with cancer treated with chemotherapy agents such as doxorubicin (DOX) develop cardiovascular toxicity, providing an opportunity to evaluate cardioprotective strategies in the setting of cancer treatment translatable to human disease. However, due to the lack of a suitable approach to culture primary adult canine cardiomyocytes, mechanistic interrogation of cardiotoxicity after cancer therapy remains a challenge. Our study thus aims to validate a canine myocardial slice culture model to study autophagy modulation and the role of extracellular vesicle (EV) associated miRNA in the setting of DOX induced cardiotoxicity. We hypothesize that induction of autophagy in canine myocardial tissue will reduce apoptosis, exert early changes to EVs, and ameliorate DOX cardiotoxicity. Left ventricular tissue from client-owned donated adult dog hearts was sectioned with a vibratome and viability of the cultured myocardial slices was evaluated by histology and MTT assay. Apoptosis was quantified by TUNEL, and autophagy by fluorescent LC3 protein puncta. Secreted EVs were isolated from cultured tissue by size exclusion chromatography and characterized by nanoparticle tracking analysis, transmission electron microscopy and immunoblot. Canine myocardial slices are consistently viable for 7 days in culture - cardiomyocyte morphology is maintained with low levels of apoptosis, and baseline autophagy is observed. Induction of autophagy with rapamycin treatment results in reduced apoptosis. Cardiac tissue derived extracellular vesicles showed typical size, morphology and enrichment of proteins including tetraspanin CD9 and will be evaluated for changes to EV miRNA profile with autophagy modulation. The canine myocardial slice model allows, for the first-time, the elucidation of complex cross-talk among apoptosis, autophagy, and EVs with molecular and cellular resolutions. Detecting early changes in canine cardiomyocyte autophagy to halt cardiac damage rather than managing its consequences is a paradigm shift translatable towards preventing chemotherapy associated cardiotoxicity.

Non-syndromic mitral valve prolapse (MVP), or Barlow’s Disease, is a valvular heart disease with a prevalence of 2-3% in the human adult population. Consequences of MVP include mitral regurgitation that without surgical treatment can progress to congestive heart failure, arrhythmias and sudden death. Since MVP is a degenerative disease that worsens with age, surgical risk is of concern with an older population, necessitating the development of alternative strategies for early detection and effective medical intervention. Similar to humans, canine MVP is age-related with a lifetime prevalence close to 90%, providing a large population for study. Canine MVP represents a relevant spontaneous large animal model to dissect the mechanistic underpinnings of disease pathogenesis and evaluate novel treatment. We hypothesize that extracellular vesicles (EVs) and their associated non-coding RNA (ncRNA) may play a role in this disease by enabling propagation of the fibroblast-to-myofibroblast phenotypic switch in mitral valvular interstitial cells (VICs). VICs were isolated from 12 normal and 14 diseased canine mitral valves and cultured in defined chemical media for 48 hours. EVs were isolated from conditioned media using size exclusion chromatography. Total RNA was isolated from EVs with the Qiagen miReasy Plasma/Serum kit, and from VIC cells with the mirVana miRNA Isolation Kit. Sequencing libraries were created using QIAseq miRNA Library Kit, and RNAseq was performed with Illumina HiSeq 2500 sequencer with single read 100 base format. Reads were mapped to canine ncRNA databases (miRbase, RFam). VICs from diseased valves had higher expression of αSMA than cells from normal valves (p = 0.002) based on RT-qPCR. Sequence analysis showed decreased content of tRNA (p = 0.023) and miRNA precursor (p = 0.036) in EVs from diseased VICs, in addition to decreased expression of let-7f. Cells from diseased valves had lower Y-RNA content (p = 0.007). miR-8859a and miR-451 were preferentially packaged into EVs from both normal and diseased VICs. Preferential packaging of miR-155 was seen in normal VIC EVs and miR-191 in diseased VIC EVs. Functional roles of these miRs will need to be confirmed to determine their therapeutic potential for treatment of MVP.

A 13-year-old male castrated pomeranian cross was referred for evaluation of episodes of collapse and a suspected cardiac mass. The presence of a mass at the base of the heart within the pericardial space was confirmed by echocardiography. Additional diagnostics included computed tomography, ultrasound-guided fine-needle aspirate, and thoracic radiographs. The mass was surgically debulked and diagnosed as myxosarcoma via histopathology. This case report describes the diagnostic imaging, laboratory findings, and short-term positive clinical outcome of a dog with a myxosarcoma in a previously undescribed location.

OBJECTIVE To compare effects of 2 IM sedation protocols, alfaxalone-butorphanol (AB) versus dexmedetomidine-butorphanol (DB), on echocardiographic (ECHO) variables in cats following sedation and blood donation. DESIGN Experimental randomized, blinded crossover study. SETTING University teaching hospital. ANIMALS Eleven client-owned healthy cats. INTERVENTIONS Cats received a baseline ECHO without sedation prior to their first donation. Cats were sedated intramuscularly with AB (alfaxalone, 2 mg/kg, and butorphanol, 0.2 mg/kg) for 1 donation and DB (dexmedetomidine, 10 μg/kg, and butorphanol 0.2, mg/kg) for another, with a minimum 6 weeks between donations. A post-sedation, post-donation ECHO was performed after each blood donation. MEASUREMENTS AND MAIN RESULTS Eight cats completed the study. Compared to baseline, DB combined with blood donation decreased heart rate (-84/min; P

Objective To describe the clinical use of rivaroxaban in the treatment of 4 dogs with vascular thrombosis, 2 with pulmonary thromboembolism and 2 with systemic thrombosis. Case Series Summary This report describes the use of a direct factor Xa anticoagulant newly approved in human patients for the treatment or prevention of arterial or venous thrombosis. The use of this medication in a clinical setting for canine patients with thromboembolism has not been described before. Two patients were treated with rivaroxaban for pulmonary thromboembolism. Decreases in thrombus size were seen in both patients, but one patient suffered acute respiratory distress and was euthanized while the other continued to do well at the time of this writing. The other 2 patients were treated for systemic thrombosis. Decreases in thrombus size were also noted. One patient later suffered hematochezia of unknown cause, and the other continued to do well at the time of this writing. New or Unique Information Provided This is the first published report of the use of a new oral direct factor Xa anticoagulant in dogs in a clinical setting for the treatment of both pulmonary and systemic thrombosis. In this case series, we share our limited experience in the use of this new medication, our strategy in determining appropriate dosages, and our monitoring protocol.

Mesenchymal stem cells (MSCs) are widely investigated as potential therapeutic agents due to their potent immunomodulatory capacity. Although specific mechanisms by which MSC acts on immune cells are emerging, many questions remain, including the potential of extracellular vesicles (EVs) to mediate biological activities. Canine MSCs are of interest for both veterinary and comparative models of disease and have been shown to suppress CD4

Although recent studies have revealed that heart cells are generated in adult mammals, the frequency of generation and the source of new heart cells are not yet known. Some studies suggest a high rate of stem cell activity with differentiation of progenitors to cardiomyocytes. Other studies suggest that new cardiomyocytes are born at a very low rate, and that they may be derived from the division of pre-existing cardiomyocytes. Here we show, by combining two different pulse-chase approaches--genetic fate-mapping with stable isotope labelling, and multi-isotope imaging mass spectrometry--that the genesis of cardiomyocytes occurs at a low rate by the division of pre-existing cardiomyocytes during normal ageing, a process that increases adjacent to areas of myocardial injury. We found that cell cycle activity during normal ageing and after injury led to polyploidy and multinucleation, but also to new diploid, mononucleate cardiomyocytes. These data reveal pre-existing cardiomyocytes as the dominant source of cardiomyocyte replacement in normal mammalian myocardial homeostasis as well as after myocardial injury.

We discuss a method for fabricating strained Si layers via deposition directly onto planarized relaxed SiGe virtual substrates, a process termed direct regrowth (DRG). We show that a trade-off exists between surface roughness and cleanliness of the Si/SiGe interface. Using this knowledge, we discuss process requirements to ensure that strained Si wafers produced via direct regrowth are free of interfacial contamination, exhibit ultra-low surface roughness, and feature abrupt Si/SiGe interfacial transitions. Finally, we show that metal-oxide-semiconductor field-effect transistors produced on strained Si channels fabricated via direct regrowth exhibit excellent device performance, suggesting the viability of the DRG process for manufacture of high quality strained Si wafers.

In order to study the luminescent efficiency of InGaAs quantum wells on Si via SiGe interlayers, identical In0.2Ga0.8As quantum well structures with GaAs and Al0.25Ga0.75As cladding layers were grown on several substrates by an atmospheric metalorganic vapor deposition system. The substrates used include GaAs, Si, Ge, and SiGe virtual substrates. The SiGe virtual substrates were graded from Si substrates to 100% Ge content. Because of the small lattice mismatch between GaAs and Ge (0.07%), high-quality GaAs-based thin films with threading dislocation densities

We have determined the critical cracking thickness, or the thickness beyond which crack formation is favored, in GaAs films grown on Si and SiGe virtual substrates analytically and experimentally. The analytical model predicts a critical cracking thickness proportional to the biaxial modulus and the crack resistance of the GaAs film, and inversely proportional to the square of the thermal stress and a nondimensional crack resistance number Z. This Z number is determined by the mechanical properties of the GaAs film for a system without substrate damage, and is also determined by the mechanical properties of the substrate for a system with substrate damage. The experimentally determined critical thicknesses were in general greater than the analytically derived values due to the kinetic barriers to crack nucleation, which were not taken into consideration in the models. In addition, we have observed an asymmetric crack array formation, where arrays running in the 〈110〉 substrate off-cut direction are favored. We have also performed finite element modeling of the crack systems to study the evolution of thermal stress around crack planes in the GaAs film.

GaAs/AlxGa(1−x)As quantum well lasers have been demonstrated via organometallic chemical vapor deposition on relaxed graded Ge/GexSi(1−x) virtual substrates on Si. A number of GaAs/Ge/Si integration issues including Ge autodoping behavior in GaAs, reduced critical thickness due to thermal expansion mismatch, and complications with mirror facet cleaving have been overcome. Despite unoptimized laser structures with high series resistance and large threshold current densities, surface threading dislocation densities for GaAs/AlGaAs lasers on Si substrates as low as 2×106 cm−2 permitted continuous room-temperature lasing at a wavelength of 858 nm. The laser structures are uncoated edge-emitting broad-area devices with differential quantum efficiencies of 0.24 and threshold current densities of 577 A/cm2. Identical devices grown on commercial GaAs substrates showed similar behavior. This comparative data agrees with previous measurements of near-bulk minority carrier lifetimes in GaAs grown on Ge/GeSi/Si substrates.

Canine myxomatous mitral valve disease (MMVD) resembles the early stages of myxomatous pathology seen in human non-syndromic mitral valve prolapse, a common valvular heart disease in the adult human population. Canine MMVD is seen in older subjects, suggesting age-related epigenetic dysregulation leading to derangements in valvular cell populations and matrix synthesis or degradation. We hypothesized that valvular interstitial cells (VICs) undergo disease-relevant changes in miRNA expression. In primary VIC lines from diseased and control valves, miRNA expression was profiled using RT-qPCR and next generation sequencing. VICs from diseased valves showed phenotypic changes consistent with myofibroblastic differentiation (vimentinlow+, α-SMAhigh+), increases in senescence markers (p21, SA-β-gαl), and decreased cell viability and proliferation potential. RT-qPCR and miRNA sequencing analyses both showed significant (p

Working optical links epitaxially grown by atmospheric MOCVD and fabricated on Si via SiGe virtual substrates are demonstrated for the first time. The SiGe virtual substrates are graded from Si substrates to 100% Ge. Because of the 0.07% lattice mismatch between GaAs and Ge, high-quality GaAs-based thin films with threading dislocation densities

Objectives Cardiac cachexia, a loss of lean body mass caused by heart disease, often accompanies congestive heart failure (CHF). Blocking myostatin, which is a protein that inhibits muscle growth, appears to greatly enhance muscle size and strength in rodent models and human clinical trials. The objective of this study was to evaluate a dog-specific myostatin antagonist (CAP-031) in a pilot study to test its safety and efficacy in dogs with CHF and cardiac cachexia. Animals Dogs with CHF and cardiac cachexia. Methods Eligible dogs received four weekly subcutaneous injections of CAP-031. Endpoints were body weight, body condition score (BCS, on a 1–9 scale), muscle condition score (MCS, on a five-point scale, where 0 = no muscle loss and 4 = severe muscle loss), appetite, and a quality of life (QOL) score. Results Seven dogs with CHF and moderate-to-severe cachexia were enrolled in the study. For the six dogs that completed the study, the median age was 8.8 years (range 6.4–10.6). At baseline, the median body weight was 27.0 kg (range 17.3–62.0), the median BCS was 4 (2–5), and median MCS was 3 (3–4). There were no significant changes in body weight, BCS, appetite, or QOL score. The change in MCS (from a median of 3 at baseline to a median of 2.5 at week 4) was not statistically significant ( p = 0.06). Conclusions The myostatin antagonist appeared to be well tolerated in most dogs. Earlier identification of cachexia is important, and randomized, controlled trials of myostatin antagonists or other drugs to treat cardiac cachexia are needed.

To evaluate the responsiveness and optimal timing of a validated health-related quality of life questionnaire, and to assess the relationship between quality of life, severity of disease, and N-terminal pro B-type natriuretic peptide (NT-proBNP) in cats with acute congestive heart failure (CHF).Thirty client-owned cats with acute CHF.Echocardiography, International Small Animal Cardiac Health Council (ISACHC) stage, and NT-proBNP were assessed in cats within 36 h of admission. The Cats' Assessment Tool for Cardiac Health (CATCH) Questionnaire (range of 0-80, with 80 being the worst possible score) was completed by cat owners and ISACHC stage was assessed at the time of hospital discharge, 3 days after discharge, and 7-14 days after discharge. NT-proBNP concentration was reassessed 7-14 days after discharge.The ISACHC stage at time of admission improved significantly by reevaluation 7-14 days after discharge (P0.001). The decrease in median NT-proBNP concentration from time of admission (655 pmol/L; range, 188 to1500 pmol/L) to reevaluation (583 pmol/L; range, 41 to1500 pmol/L) was not significant (P = 0.59). Median CATCH score was 26 (range, 0-70) at baseline, 19 (range, 0 to 61) at discharge, and 19 (range, 2-49) 7-14 days after discharge (P = 0.89). CATCH scores did not correlate with NT-proBNP concentrations or ISACHC stage.These results suggest that the CATCH questionnaire requires further refinement for uses requiring a responsive instrument in cats with acute CHF.

To describe the clinical use of rivaroxaban in the treatment of 4 dogs with vascular thrombosis, 2 with pulmonary thromboembolism and 2 with systemic thrombosis.This report describes the use of a direct factor Xa anticoagulant newly approved in human patients for the treatment or prevention of arterial or venous thrombosis. The use of this medication in a clinical setting for canine patients with thromboembolism has not been described before. Two patients were treated with rivaroxaban for pulmonary thromboembolism. Decreases in thrombus size were seen in both patients, but one patient suffered acute respiratory distress and was euthanized while the other continued to do well at the time of this writing. The other 2 patients were treated for systemic thrombosis. Decreases in thrombus size were also noted. One patient later suffered hematochezia of unknown cause, and the other continued to do well at the time of this writing.This is the first published report of the use of a new oral direct factor Xa anticoagulant in dogs in a clinical setting for the treatment of both pulmonary and systemic thrombosis. In this case series, we share our limited experience in the use of this new medication, our strategy in determining appropriate dosages, and our monitoring protocol.

Recent advances in the understanding and control of threading dislocations in substantially relaxed SiGe buffer layers on Si are presented. A model for threading dislocation flow in relaxed graded SiGe buffers is used to determine the potential lower limit of threading dislocation density in relaxed SiGe buffers. Greater densities than expected from the model are seen in relaxed graded alloys with final concentrations greater than 50%. We show that the culprits of the higher threading dislocation density are threading dislocation pile-ups. Observation of early development of pile-ups confirms that inhomogeneous misfit dislocation densities in the graded buffer form regions of more severe crosshatch on the surface that impede dislocation flow. By using chemomechanical planarization (CMP), deleterious pile-up formation can be avoided, and previously formed pile-ups can be destroyed by regrowth of a graded layer. Experiments with CMP and regrowth of graded layers suggest that dislocation annihilation can be effective at reducing threading dislocation densities to densities of the order expected by the model. High quality Ge on Si layers created with the CMP process were used as templates to grow high quality GaAs on Si with strong room temperature photoluminescence and record minority carrier lifetime.

SiGe-free strained Si on insulator substrates were fabricated by wafer bonding and hydrogen-induced layer transfer of strained Si grown on bulk relaxed Si0.68Ge0.32 graded layers. Raman spectroscopy shows that the 49-nm thick strained Si on insulator structure maintains a 1.15% tensile strain even after SiGe layer removal. The strain in the structure is thermally stable during 1000 °C anneals for at least 3 min, while more extreme thermal treatments at 1100 °C cause slight film relaxation. The fabrication of epitaxially defined, thin strained Si layers directly on a buried insulator forms an ideal platform for future generations of Si-based microelectronics.

Objective—To compare morphometric measurements and serum insulin-like growth factor (IGF-1) concentration in cats with and without hypertrophic cardiomyopathy (HCM), and assess the hypothesis that cats with HCM have larger body size and skeletal features and higher serum IGF-1 concentrations than healthy cats. Animals—25 cats with HCM and 22 healthy control cats. Procedures—Physical examination and echocardiography were performed to classify cats into the HCM and control groups. Data collected from each cat included diet history, body weight, body condition score, lengths of the humerus and 4th and 12th thoracic vertebrae, heart size, head length and width, and abdominal circumferences. Comparisons of these variables were made between groups. Results—Body condition score in HCM-affected and control cats did not differ significantly. However, median head width; lengths of the head, 4th and 12th thoracic vertebrae, and humerus; and body weight in the HCM-affected group were significantly greater than values in the control group. Median serum concentration of IGF-1 was not significantly different between groups. Conclusions and Clinical Relevance—These data suggested that among the study cats, those with HCM were skeletally larger, but not more obese, than healthy cats. Whether this was attributable to differences in early growth or other causes requires additional investigation.

AlxGa(1−x)As/GaAs quantum well lasers have been demonstrated via organometallic chemical vapor deposition (OMCVD) on relaxed graded GexSi(1−x) virtual substrates on Si. Despite unoptimized laser structures with high series resistance and large threshold current densities, surface threading dislocation densities as low as 2×106 cm−2 enabled cw room-temperature lasing at a wavelength of 858nm. The laser structures are oxide-stripe gain-guided devices with differential quantum efficiencies of 0.16 and threshold current densities of 1550A/cm2. Identical devices grown on commercial GaAs substrates showed differential quantum efficiencies of 0.14 and threshold current densities of 1700A/cm2. This comparative data agrees with our previous measurements of near-bulk minority carrier lifetimes in GaAs grown on Ge/GeSi/Si substrates. A number of GaAs/Ge/Si integration issues including thermal expansion mismatch and Ge autodoping behavior in GaAs were overcome.

The realization of monolithic optical interconnects by integration of III-V materials with conventional Si circuitry has long been hindered by materials incompatibilities (i.e. lattice mismatch and heterovalent interface) and practical processing constraints. We have demonstrated successful integration of hetero-epitaxially grown InGaAs/Si diodes with an n-well CMOS process on (001) Si offcut 6 degrees towards [110]. The In0.15Ga0.85As/InxGa1- xAs/GaAs/Si diodes were grown by atmospheric pressure organo-metallic chemical vapor deposition (OMCVD) and features a room temperature R0A product of 20,000 ohm-cm2. No degradation of PMOS or NMOS transistor characteristics was detected upon integration of the III-V devices. Further improvement of III-V/Si device characteristics are anticipated in future efforts by incorporating relaxed, compositionally- graded Ge/GexSi1-x/Si with low threading dislocation densities (approximately 2 X 106/cm2) to bridge the gap in lattice constants between Si and GaAs. Recent progress towards this end includes the suppression of antiphase disorder during GaAs growth on Ge/GexSi1-x/Si by OMCVD and strong room temperature photoluminescence from In0.20Ga0.80As QW test structures on GaAs/GexSi1- x/Si at 920 nm.