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This study evaluated four over the counter venison dry dog foods available from one on-line retail vendor for potential contamination with common known food allergens: soy, poultry or beef. An amplified, double sandwich type enzyme linked immunosorbent assay (ELISA) test of soy, poultry and beef proteins were performed by an independent accredited food laboratory. The ELISA test for poultry protein was found to be unreliable when testing in dry dog foods because false negatives occurred. ELISA testing of control diets for both soy and beef proteins performed as expected and could be useful in antigen testing in dry dog foods. Three of the four over the counter (OTC) venison canine dry foods with no soy products named in the ingredient list were ELISA positive for soy; additionally one OTC diet tested positive for beef protein with no beef products listed as an ingredient list. One OTC venison diet was not found to be positive for soy, poultry or beef proteins. However, none of the four OTC venison diets could be considered suitable for a diagnostic elimination trial as they all contained common pet food proteins, some of which were readily identifiable on the label and some that were only detected by ELISA. Therefore, if the four OTC venison products selected in this study are representative of OTC products in general, then the use of OTC venison dry dog foods should not be used during elimination trials in suspected food allergy patients. [ABSTRACT FROM AUTHOR]

We present a systematic spectral-timing analysis of a fast appearance/disappearance of a type-B quasi-periodic oscillation (QPO), observed in four Neutron Star Interior Composition Explorer (NICER) observations of MAXI J1348−630. By comparing the spectra of the period with and without the type-B QPO, we found that the main difference appears at energy bands above ∼2 keV, suggesting that the QPO emission is dominated by the hard Comptonized component. During the transition, a change in the relative contribution of the disc and Comptonized emission was observed. The disc flux decreased while the Comptonized flux increased from non-QPO to type-B QPO. However, the total flux did not change too much in the NICER band. Our results reveal that the type-B QPO is associated with a redistribution of accretion power between the disc and Comptonized emission. When the type-B QPO appears, more accretion power is dissipated into the Comptonized region than in the disc. Our spectral fits give a hint that the increased Comptonized emission may come from an additional component that is related to the base of the jet. [ABSTRACT FROM AUTHOR]

We present detailed timing and spectral studies of the black hole candidate MAXI J0637–430 during its 2019–2020 outburst using observations with the Neutron Star Interior Composition Explorer (NICER) and the Neil Gehrels Swift Observatory. We find that the source evolves through the soft-intermediate, high-soft, hard-intermediate, and low-hard states during the outburst. No evidence of quasi-periodic oscillations is found in the power-density spectra of the source. Weak variability with fractional rms amplitude |${\lt}5{{\ \rm per\ cent}}$| is found in the softer spectral states. In the hard-intermediate and hard states, high variability with the fractional rms amplitude of |${\gt}20{{\ \rm per\ cent}}$| is observed. The 0.7–10 keV spectra with NICER are studied with a combined disc-black-body and nthcomp model along with the interstellar absorption. The temperature of the disc is estimated to be 0.6 keV in the rising phase and decreased slowly to 0.1 keV in the declining phase. The disc component was not detectable or absent during the low-hard state. From the state-transition luminosity and the inner edge of the accretion flow, we estimate the mass of the black hole to be in the range of 5–12 M⊙, assuming the source distance of d < 10 kpc. [ABSTRACT FROM AUTHOR]

Following a tidal disruption event (TDE), the accretion rate can evolve from quiescent to near-Eddington levels and back over timescales of months to years. This provides a unique opportunity to study the formation and evolution of the accretion flow around supermassive black holes (SMBHs). We present 2 yr of multiwavelength monitoring observations of the TDE AT2018fyk at X-ray, UV, optical, and radio wavelengths. We identify three distinct accretion states and two state transitions between them. These appear remarkably similar to the behavior of stellar-mass black holes in outburst. The X-ray spectral properties show a transition from a soft (thermal-dominated) to a hard (power-law-dominated) spectral state around Lbol ∼ few × 10−2LEdd and the strengthening of the corona over time ∼100–200 days after the UV/optical peak. Contemporaneously, the spectral energy distribution (in particular, the UV to X-ray spectral slope αox) shows a pronounced softening as the outburst progresses. The X-ray timing properties also show a marked change, initially dominated by variability at long (>day) timescales, while a high-frequency (∼10−3 Hz) component emerges after the transition into the hard state. At late times (∼500 days after peak), a second accretion state transition occurs, from the hard into the quiescent state, as identified by the sudden collapse of the bolometric (X-ray+UV) emission to levels below 10−3.4LEdd. Our findings illustrate that TDEs can be used to study the scale (in)variance of accretion processes in individual SMBHs. Consequently, they provide a new avenue to study accretion states over seven orders of magnitude in black hole mass, removing limitations inherent to commonly used ensemble studies. [ABSTRACT FROM AUTHOR]

We studied the outburst evolution and timing properties of the recently discovered X-ray transient MAXI J1348−630 as observed with NICER. We produced the fundamental diagrams commonly used to trace the spectral evolution, and power density spectra to study the fast X-ray variability. The main outburst evolution of MAXI J1348−630 is similar to that commonly observed in black hole transients. The source evolved from the hard state (HS), through hard- and soft-intermediate states, into the soft state in the outburst rise, and back to the HS in reverse during the outburst decay. At the end of the outburst, MAXI J1348−630 underwent two reflares with peak fluxes approximately one and two orders of magnitude fainter than the main outburst, respectively. During the reflares, the source remained in the HS only, without undergoing any state transitions, which is similar to the so-called 'failed outbursts'. Different types of quasi-periodic oscillations (QPOs) are observed at different phases of the outburst. Based on our spectral-timing results, we conclude that MAXI J1348−630 is a black hole candidate. [ABSTRACT FROM AUTHOR]

After 26 yr in outburst, the black hole X-ray binary GRS 1915+105 dimmed considerably in early 2018; its flux dropped sharply in mid-2019, and it has remained faint ever since. This faint period, the "obscured state," is punctuated by occasional X-ray flares, many of which have been observed by NICER as part of our regular monitoring program. Here we present detailed time-resolved spectroscopy of one bright flare, whose spectrum shows evidence of high column density partial covering absorption and extremely deep absorption lines (equivalent widths over 100 eV in some cases). We study the time-dependent ionization of the obscuring gas with xstar , ultimately attributing the absorption to a radially stratified absorber of density ∼1012–1013 cm−3 at ∼few ×1011 cm from the black hole. We argue that a vertically extended outer disk could explain this obscuration. We discuss several scenarios to explain the obscured state, including massive outflows, an increase in the mass accretion rate, and changes in the outer disk that herald the approach of quiescence, but none are entirely satisfactory. Alternative explanations, such as obscuration by the accretion stream impact point, may be testable with current or future data. [ABSTRACT FROM AUTHOR]

The black hole candidate and X-ray binary MAXI J1535−571 was discovered in 2017 September. During the decay of its discovery outburst, and before returning to quiescence, the source underwent at least four reflaring events, with peak luminosities of ∼1035–36 erg s−1 (d /4.1 kpc)2. To investigate the nature of these flares, we analysed a sample of NICER (Neutron star Interior Composition Explorer) observations taken with almost daily cadence. In this work, we present the detailed spectral and timing analysis of the evolution of the four reflares. The higher sensitivity of NICER at lower energies, in comparison with other X-ray detectors, allowed us to constrain the disc component of the spectrum at ∼0.5 keV. We found that during each reflare the source appears to trace out a q-shaped track in the hardness–intensity diagram similar to those observed in black hole binaries during full outbursts. MAXI J1535−571 transits between the hard state (valleys) and softer states (peaks) during these flares. Moreover, the Comptonized component is undetected at the peak of the first reflare, while the disc component is undetected during the valleys. Assuming the most likely distance of 4.1 kpc, we find that the hard-to-soft transitions take place at the lowest luminosities ever observed in a black hole transient, while the soft-to-hard transitions occur at some of the lowest luminosities ever reported for such systems. [ABSTRACT FROM AUTHOR]

We present the results of our intensive radio observing campaign of the dwarf nova SS Cyg during its 2010 April outburst. We argue that the observed radio emission was produced by synchrotron emission from a transient radio jet. Comparing the radio light curves from previous and subsequent outbursts of this system (including high-resolution observations from outbursts in 2011 and 2012) shows that the typical long and short outbursts of this system exhibit reproducible radio outbursts that do not vary significantly between outbursts, which is consistent with the similarity of the observed optical, ultraviolet and X-ray light curves. Contemporaneous optical and X-ray observations show that the radio emission appears to have been triggered at the same time as the initial X-ray flare, which occurs as disc material first reaches the boundary layer. This raises the possibility that the boundary region may be involved in jet production in accreting white dwarf systems. Our high spatial resolution monitoring shows that the compact jet remained active throughout the outburst with no radio quenching. [ABSTRACT FROM AUTHOR]

ABSTRACT We present an intensive radio and X-ray monitoring campaign on the 2009 outburst of the Galactic black hole candidate X-ray binary H1743−322. With the high angular resolution of the Very Long Baseline Array, we resolve the jet ejection event and measure the proper motions of the jet ejecta relative to the position of the compact core jets detected at the beginning of the outburst. This allows us to accurately couple the moment when the jet ejection event occurred with X-ray spectral and timing signatures. We find that X-ray timing signatures are the best diagnostic of the jet ejection event in this outburst, which occurred as the X-ray variability began to decrease and the Type C quasi-periodic oscillations disappeared from the X-ray power density spectrum. However, this sequence of events does not appear to be replicated in all black hole X-ray binary outbursts, even within an individual source. In our observations of H1743−322, the ejection was contemporaneous with a quenching of the radio emission, prior to the start of the major radio flare. This contradicts previous assumptions that the onset of the radio flare marks the moment of ejection. The jet speed appears to vary between outbursts, with a possible positive correlation with outburst luminosity. The compact core radio jet reactivated on transition to the hard intermediate state at the end of the outburst, and not when the source reached the low hard spectral state. Comparison with the known near-infrared behaviour of the compact jets suggests a gradual evolution of the compact jet power over a few days near the beginning and end of an outburst. [ABSTRACT FROM AUTHOR]

We present an analysis of the Swift Burst Alert Telescope (BAT) and X-ray telescope (XRT) data of GRB060602B, which is most likely an accreting neutron star in a binary system and not a gamma-ray burst. Our analysis shows that the BAT burst spectrum is consistent with a thermonuclear flash (type I X-ray burst) from the surface of an accreting neutron star in a binary system. The X-ray binary nature is further confirmed by the report of a detection of a faint point source at the position of the XRT counterpart of the burst in archival XMM–Newton data approximately six year before the burst and in more recent XMM–Newton data obtained at the end of 2006 September (nearly four months after the burst). Since the source is very likely not a gamma-ray burst, we rename the source Swift J1749.4−2807, based on the Swift/BAT discovery coordinates. Using the BAT data of the type I X-ray burst, we determined that the source is at most at a distance of . For a transiently accreting X-ray binary, its soft X-ray behaviour is atypical: its 2–10 keV X-ray luminosity (as measured using the Swift/XRT data) decreased by nearly three orders of magnitude in about 1 day, much faster than what is usually seen for X-ray transients. If the earlier phases of the outburst also evolved this rapidly, then many similar systems might remain undiscovered because the X-rays are difficult to detect and the type I X-ray bursts might be missed by all the sky surveying instruments. This source might be part of a class of very fast transient low-mass X-ray binary systems of which there may be a significant population in our Galaxy. [ABSTRACT FROM AUTHOR]

We describe the “Monitor e Imageador de Raios-X” (MIRAX), an X-ray astronomy satellite mission proposed by the high-energy astrophysics group at the National Institute for Space Research (INPE) in Brazil to the Brazilian Space Agency. MIRAX is an international collaboration that includes, besides INPE, the University of California San Diego, the University of Tübingen in Germany, the Massachusetts Institute of Technology and the Space Research Organization Netherlands. The payload of MIRAX will consist of two identical hard X-ray cameras (10–200 keV) and one soft X-ray camera (2–28 keV), both with angular resolution of ∼5–7′. The basic objective of MIRAX is to carry out continuous broadband imaging spectroscopy observations of a large source sample (∼9 months/yr) in the central Galactic plane region. This will allow the detection, localization, possible identification, and spectral/temporal study of the entire history of transient phenomena to be carried out in one single mission. MIRAX will have sensitivities of ∼ 5 mCrab/day in the 2–10 keV band (∼2 times better than the All Sky Monitor on Rossi X-ray Timing Explorer) and 2.6 mCrab/day in the 10–100 keV band (∼40 times better than the Earth Occultation technique of the Burst and Transient Source Experiment on the Compton Gamma-Ray Observatory). The MIRAX spacecraft will weigh about 200 kg and is expected to be launched in a low-altitude (∼600 km) circular equatorial orbit around 2007/2008. [Copyright &y& Elsevier]

In hospitalized patients, a multitude of factors including loss of luminal trophic factors, altered splanchnic blood flow and nutritional deprivation lead to gastrointestinal mucosal atrophy. Clinical orders of nothing per os (NPO) or “bowel rest” cause intestinal atrophy, which leads to abnormal enteric flora with bacterial, endotoxin or cytokine translocation, altered host immune function and sepsis (Barber et al.1991, Zaloga 1994). The prevention or limitation of intestinal atrophy during small bowel disuse or “rest” would have clinical significance if fewer hospital days and lower infection rates resulted. Glutamine is the preferred respiratory fuel for enterocytes; administration of 2% glutamine solutions is known to be beneficial in the short term. However, glutamine is more like a conditionally essential amino acid, necessary only during recovery to stimulate DNA synthesis and increase mucosal mass (Lacey and Wilmore 1990). Glutamine administered intravenously (IV) long term to animals with intestinal atrophy has not been adequately investigated in clinically relevant species. Enteral feedings are also known to be beneficial in preventing intestinal disuse. Data in critically injured patients suggest that enteral nutrition had a positive effect on intestinal immune function and leads to decreased infectious morbidity and reduced hospital stay (Heyland et al.1993). Possible advantages of feeding small volumes enterally during prolonged periods of small bowel “rest” therapy have also not been investigated, but such feeding is quite possible in most hospitalized cases as a means of minimizing intestinal atrophy. The objective of this study was to compare the small intestinal response to intravenous glutamine vs. intermittent small volume enteral feedings, administered for .1 wk as a means of preventing intestinal atrophy. The piglet has become the preferred small intestinal research model because of the homology among the swine, human, canine, feline and equine small bowels. The small intestines of the dog, cat, pig and foal are very similar in morphology and physiology through the first year of life, and the atrophic response to NPO also appears to be similar. The information derived from a swine research model of small intestinal atrophy is, therefore, relevant to the small bowel changes after disuse in dogs, cats and foals. Materials and methods. Five litters of Hampshire × Duroc piglets were selected on the basis of body weight (BW) (1.8 –2.7 kg) at 4 d of age. Four litter mates were randomly assigned to one of the following four treatments: 1) 100% enterally fed sow’s milk replacer (SMR); 2) total parenteral nutrition (TPN); 3) TPN with 1.7% (wt/v) glutamine (GLN); or 4) 90% of total energy as TPN plus 10% enterally as SMR (PEN). The TPN treatment served as a negative control, whereas SMR served as a positive control. Because of logistical limitations, four litter mates (1 piglet/treatment) completed the 28-d feeding trial at a time. Piglets were maintained in accordance with the Animal Care Committee guidelines at the Johns Hopkins Medical Institutions and the Committee on Care and Use of Laboratory Animals from the Institute of Laboratory Animal Resources. Nutritional treatments. All piglets suckled sow’s colostrum/ milk until delivered to the laboratory at 4 d of age; they also received an iron dextran injection (100 mg intramuscularly) at 3 and 10 d of age. Catheters (1.0 mm i.d., 2.1 mm o.d., 91 cm) of medical grade silastic tubing (Dow Corning, Midland, MI) were surgically placed in the left and right external jugular veins of all piglets. The catheter tips were inserted into the cranial vena cava; the proximal end of the catheter was tunneled to the dorsum, passing cranially to the shoulder and exiting 5–10 cm posterior to the ear. One catheter was used for parenteral administration, and the second was used for blood sampling. Weekly blood samples were drawn for complete blood cell count with a differential and serum profile. All piglets were individually housed in stainless steel (60 × 60 × 60 cm3) cages with plastic mesh-covered screened floors, and maintained in nylon open mesh vests with an attached stainless steel tether line (Spalding Medical Research Products, Birmingham, AL) and swivel infusion system. All piglets were administered 630 kJ/(kg BW • d) of their respective nutritional treatments on the basis of daily BW and were maintained on these diets as the sole source of nutrition for 4 wk. TPN solution was formulated to have a nutrient profile recommended (NRC1988) for piglets <5 kg BW (Table 1). The amino acid component of the TPN solution was made by adding 56 g nonessential amino acids/L (Sigma Chemical, St. Louis, MO) to a commercial 11.4% amino acid product (Novamine, Clintec Nutrition, Deerfield, IL), whereas the GLN solution was formulated by adding 56 g glutamine/L. The 20% lipid solution (Intralipid, Kabivitrum, Alameda, CA) was infused by a separate pump and connection into the catheter line. The final parenteral solution administered to GLN piglets contained 17 g glutamine/L. The parenteral solutions were made once every 24 h and administered continuously for 28 d. The sow’s milk replacer (SMR) (Acidified Pig Milk Replacer, Milk Specialties, Dundee, IL) (Table 1) was a whey-based commercial product designed for young growing piglets. A 10% SMR solution was made daily and offered to the SMR piglets in amounts equal to the caloric intake of the TPN and GLN piglets. PEN piglets received 90% of their caloric intake similarly to the TPN piglets and the remaining 10% as SMR piglets. The daily allotted volume of SMR was offered at one time to the SMR and PEN piglets by using a plastic feeder attached to the cage and was consumed in a single-meal feeding pattern. Intestinal assays and data compilation. After 4 wk of feeding, piglets were anesthetized; a 20-cm jejunal segment was removed 30 cm distal to a suspensory ligament of the duodenum, and a 20-cm ileal segment was excised 10 cm proximal to the ileocecal sphincter. Segments were flushed with cold saline, weighed and the length was measured with a 15-g free-hanging weight. Pieces 2 cm in length from both segments were either fixed in 10% buffered formalin for histology or had mucosa scraped free, frozen in liquid nitrogen and stored at -70°C for mucosal disaccharidase assay. Piglets were killed by exsanguination while under general anesthesia as the visceral organs were removed and weighed. The remaining intestinal tract was flushed free of digesta with tap water and measured in sections as suspended with a 15-g free-hanging weight. The total small intestinal weight and length were calculated adding back all segments removed. Jejunal and ileal villous height and crypt depth were determined by a pathologist with the use of hematoxylin and eosin–stained tissues at an average of 12 vertically oriented sites. Sucrase, maltase and lactase brush border activities were measured in jejunal and ileal mucosal samples using a Tris/glucose oxidase reagent (Dahlqvist 1984). Mucosal protein was determined using a bovine plasma γ-globulin standard (Protein Assay Kit, Bio- Rad DC Laboratories, Richmond, CA). Data were analyzed statistically using a one-factor ANOVA, and results were reported as treatment means ± 1 SD. The mean separation Dunnett’s t test (2-tailed, a = 0.05) compared TPN, GLN and PEN treatments to the SMR control, and then GLN and PEN treatments to the TPN control with significance at P≤ 0.05. Results. The initial (2.37 ± 0.5 kg) and final (4.03 ± 1.4 kg) body weights of piglets were not different across assigned treatment groups; however, the daily intakes of energy, fat and amino acids tended to be lower in the TPN, GLN and PEN groups than in the SMR treatment group (Table 2). The nutrient intake differences between parenterally and enterally fed piglets can be explained by automatic parenteral pump shut-offs and occlusions that occurred over the 28-d study. Small bowel (SB) weights per unit of body weight (Table 2) were compared across treatments as a more conservative method by which to test relative gastrointestinal atrophy. SB weights of TPN-, GLN- and PEN-treated piglets were significantly less than that of SMR-treated piglets. There were no differences in other organ weights or intestinal lengths between SMR and parenterally fed (TPN, GLN and PEN) piglets, except for liver weights, which were significantly greater in parenterally fed piglets (>4% BW) compared with SMR fed piglets (2.5% BW). During wk 4, serum bilirubin and aspartate aminotransferase were not different between treatment groups; however, alanine aminotransferase and alkaline phosphatase in TPN and GLN serum were significantly greater than SMR serum values, whereas PEN serum values were intermediate. Small intestinal histology (Table 2) was affected by route of nutrition because parenteral administration decreased villous heights by 50% in the jejunum and by 25% in the ileum, and SMR piglets had jejunal and ileal villus:crypt ratios greater than the other three piglet groups. Within parenteral treatment groups, jejunal villous heights in the PEN group were greater than those in the TPN group; however, crypt depths were significantly greater in the PEN and GLN piglets than in the TPN group. Jejunal lactase and sucrase activities for TPN and GLN piglets were significantly less than those of SMR piglets, whereas activities of PEN-treated piglets were intermediate (Table 2). Ileal lactase and sucrase activities in SMR piglets were uniformly greater than those of TPN-, GLN- and PEN-treated piglets. Maltase activity in the jejunum and ileum, however, was not affected by the route of nutritional administration and remained uniform across treatments [150 ± 63/(min • g protein)]. Discussion. The 4-wk parenteral administration of nutrients to piglets did produce a small bowel (SB) disuse atrophy and hepatomegaly. Although there were no significant differences in final body weight or gain, TPN-fed piglets had significantly lower SB weights, shorter jejunal and ileal villous heights and lower SB enzyme activity than the positive control SMR-fed piglets. The negative control TPN treatment findings were consistent with previously reported results. In TPN-fed adult rats, glutamine has been shown to prevent decreased intestinal weight, DNA content, villous height, and sucrase and lactase activities when administered IV for 6–7 d. In this 4-wk swine study, SB weights and enzyme activities were not preserved with glutamine added to the TPN solution. Glutamine in the TPN solutions may have spared jejunal crypt cell atrophy; however, villous heights were not spared. The difference between the previous studies demonstrating some advantage in giving glutamine and this study demonstrating no clear advantage may be related to differences in the species (rats vs. pigs), age of the animal models (adult vs. young) but more likely, length of treatment time (1 vs. 4 wk). In dogs, there is an increased requirement for glutamine during the immediate postoperative phase (<7 d), but uptake returned to normal rates later during a recovery phase (>10 d post-surgery) (Souba et al. 1987 and 1990). The long-term use of IV glutamine was not effective in preventing NPO-induced disuse atrophy. Therefore, given the high cost of IV glutamine fluids and the apparent limited time of efficacy, the use of IV glutamine solutions for dogs, cats and foals recovering from small bowels diseases should be limited to early short-term use. Piglets fed small volume enteral feedings of milk (PEN) did have jejunal villous heights and crypt depths significantly greater than those in the TPN piglets, and jejunal sucrase and lactase activities in the PEN fed piglets were intermediate to those of the SMR and TPN piglets. Piglets are farrowed with negligible amounts of maltase and sucrase activities, which develop during the first few weeks of life; however, lactase activity is high at birth and decreases with age (Ulshen et al.1991). Lactase and sucrase are known to be diet-inducible enzymes, which decreased in TPN-fed piglets, whereas maltase is not a diet-inducible enzyme (Jackson and Grand 1991), and intestinal activity remained high in all piglets. The enteral feedings apparently had minimal effect on ileal parameters, which may indicate small volume feedings of a highly digestible product may not have reached the ileum as a result of proximal bowel digestion and absorption. Apparently, the use of a milk solution, providing only 10% of the total energy intake, resulted in intermediate jejunal lactase and sucrase activities with taller villi and deeper crypts; however, this solution had no effect on overall SB weight. On the basis of these results, we believe that limited enteral milk feeding during SB disuse, if possible, has important clinical ramifications and warrants further investigation. Feeding small volumes of a well-designed enteral product to dogs, cats and foals recovering from small intestinal diseases may be a beneficial alternative to NPO. [ABSTRACT FROM AUTHOR]

Intestinal mass and function are maintained by stimulation from enteral nutrients, trophic hormones, adequate blood flow and neurologic input. Nutrients and ingredients exert profound trophic effects on the small intestine by several mechanisms. Ingested nutrients present mechanical and chemical stimuli to the intestine, which in turn releases endogenous and hormonal secretions. Second, the type and amount of ingested nutrients mechanically alter the mucosal cell mass by affecting the rate of stem cell division and the rate of mucosal cell renewal. Third, the gastric, duodenal and pancreaticobiliary secretions that normally accompany eating, digestion and absorption are known to promote mucosal structure and function. Small volume enteral feedings of milk have been shown to ameliorate some aspects of intestinal disuse atrophy in pigs. Enteral feedings begun immediately after enterostomies performed in dogs led to significantly increased mature collagen concentration and bowel strength at the site of the resection by d 5 (Moss et al. 1980). In brief, feeding enterally is the most powerful stimulus to maintaining normal morphology and function (Jackson and Grand 1991), yet clinical orders of nothing per os (NPO) are common practice. In hospitalized patients, a multitude of factors including loss of luminal trophic factors, altered splanchnic blood flow and nutritional deprivation lead to intestinal mucosal atrophy (Rock et al. 1990). The smallest volume, composition and feeding rate most effective in ameliorating disuse atrophy and maintaining intestinal functions are not known. Reintroduction of food enterally is known to reverse intestinal atrophy eventually; however, the time required for full intestinal recovery is also not known. Piglets, in contrast with rats, have become the preferred small intestinal research model because of the homology among the intestinal tracts of swine, humans and companion animals. The information derived from a swine research model of small intestinal atrophy is also relevant to the small bowel changes occurring in NPO dogs, cats and foals. The objective of this study was to assess the ability of the intestinal tract to recover from disuse atrophy with 2 wk of milk feedings by mouth vs. small volume milk feedings concurrently with total parenteral nutrition (TPN)-inducing atrophy. Materials and methods. Five litters of Hampshire × Duroc piglets were selected on the basis of body weight (BW) (2.0 –2.8 kg) at 4 d of age and used in a 4-wk TPN study followed by a 2-wk refeeding study. Three littermates were randomly assigned to one of the three following treatments: 1) 100% enterally fed sow’s milk replacer (SMR); 2) total parenteral nutrition (TPN); 3) 90% of total energy as TPN plus 10% enterally as SMR (PEN). SMR-fed piglets were positive controls and represented normal intestinal development, whereas TPN-fed piglets served as negative controls. Piglets were maintained in accordance with the Johns Hopkins Medical Institutions Animal Care and Use Committee Guidelines and the Committee on Care and Use of Laboratory Animals from the Institute of Laboratory Animal Resources. Medical grade silastic catheters (1.0 mm i.d., 2.1 mm o.d., 91 cm) (Dow Corning, Midland, MI) were surgically placed in the left and right external jugular veins of all piglets. The catheter tips were inserted into the cranial vena cava; the proximal end of the catheter was subcutaneously tunneled to the dorsum, passing cranially to the shoulder and exiting 5–10 cm posterior to the ear. Catheters were used for administering parenteral nutrition and obtaining blood samples. Weekly blood samples were drawn for complete blood cell count with a differential and serum profile. All piglets were individually housed in stainless steel (60 × 60 × 60 cm3) cages with plastic meshcovered screened floors and maintained in nylon open mesh vests with an attached stainless steel tether line (Spalding Medical Research Products, Birmingham, AL) and swivel infusion system. Nutritional treatments. All piglets suckled sow’s colostrum/ milk until delivered to the laboratory at 4 d of age; they also received an iron dextran (Iron Dextran Complex, TechAmerica, Elwood, KS) injection (100 mg intramuscularly) at 3 and 10 d of age. The TPN solution was formulated to have a nutrient profile similar to SMR and the recommended dietary concentrations for piglets <5 kg BW (NRC 1988) (Table 1). The TPN solution was administered as a three-in-one solution [dextrose, amino acids and lipid (Liposyn III 20%, Abbott Laboratories, Chicago, IL)]. The amino acid component of the TPN solution was made by adding 56 mg/mL of nonessential amino acids (Sigma Chemical, St. Louis, MO) to a commercially available 11.4% amino acid product. The zinc concentration of the parenteral solution was reduced from the NRC recommendation of 50 to 12 mg/kg because of high hepatic zinc concentrations (>500 mg/kg wet tissue) that approached toxic levels in earlier piglet studies (Gabrielson et al. 1996). The parenteral solutions were made twice weekly using a high speed compounder (Automix Plus, Clintec Nutrition, Deerfield, IL) and stored at 49C until needed. All piglets were administered 527 kJ/(kg BW • d) of their respective nutritional treatments on the basis of daily body weights and were maintained on these diets as the sole source of nutrition for 4 wk. The sow’s milk replacer (Acidified Pig Milk Replacer, Milk Specialties, Dundee, IL) (Table 1) was a whey-based commercially available product designed for young growing piglets. A 20% SMR solution was made daily and offered to the SMR piglets in amounts equal to the energy intake of TPN piglets. PEN piglets received 90% of their energy intake similarly to the TPN piglets and the remaining 10% as SMR piglets. The daily allotted volume of SMR was offered at one time to the SMR and PEN piglets using a plastic feeder attached to the cage and was consumed in a single-meal feeding pattern. After 4 wk of their respective treatments, TPN and PEN piglets were disconnected from infusion pumps. All piglets were caged individually in 10 m2 pens and were fed a 20% SMR solution once daily, which provided 544 kJ/(kg BW • d) as the sole source of nutrition for 2 wk; water was available at all times. Intestinal assays and data compilation. After 6 wk of feeding, piglets were anesthetized; a 20-cm jejunal segment was removed 30 cm distal to the suspensory ligament of the duodenum, and a 20-cm ileal segment was excised 10 cm proximal to the ileocecal sphincter. Segments were flushed with cold saline, weighed and the length was measured with a 15-g freehanging weight. Pieces 2 cm in length from both segments were either fixed in 10% buffered formalin for histology or had mucosa scraped free, frozen in liquid nitrogen, and stored at -70’C for mucosal disaccharidase assay. Piglets were killed by exsanguination while under general anesthesia as the visceral organs were removed and weighed. The remaining intestinal tract was flushed free of digesta with tap water and measured in sections as suspended with a 15-g free-hanging weight. The total small intestinal weight and length were calculated adding back all segments removed. Jejunal and ileal villous height and crypt depth were determined by a pathologist with the use of hematoxylin and eosin–stained tissues at an average of 12 vertically oriented sites. Lactase, sucrase and maltase brush border activities were measured in jejunal and ileal mucosal samples using a Tris/glucose oxidase reagent (Dahlqvist 1984). Mucosal protein was determined using a bovine plasma γ-globulin standard (Protein Assay Kit, Bio-Rad DC Laboratories, Richmond, CA). Data were statistically analyzed using a one-factor (treatment) ANOVA; significance was established at P≤ 0.05, and results are reported as treatment means ± 1 SD. The mean separation Scheffé F-test was used to compare TPN, PEN and SMR treatments. Results. The initial body weights of piglets were not different across assigned treatments (2.63 ± 0.4 kg). During the first 4-wk feeding trial, daily nutrient intakes of energy, protein and fat were significantly lower in the TPN and PEN groups than in the SMR treatment group because of automatic pump shut-offs and occlusions, and TPN piglets did have a significantly lower rate of weight gain than SMR and PEN piglets (Table 2). During the subsequent 2-wk milk refeeding phase, there were no nutrient intake differences among treatment groups. Final body weights (7.23 ± 1.4 kg) were not different across groups. Organ measurements per unit of body weight were compared across treatments as a more conservative method by which to test relative gastrointestinal atrophy. Intestinal weights and lengths, and pancreas weights were not significantly different across treatment groups after 2 wk of oral refeedings. Liver weights were significantly greater in the TPN-fed piglets (>6% BW) compared with SMR-fed piglets (4.0% BW). Liver weight of PEN-treated piglets (4.9%) was an intermediate value and not significantly different from the TPN or SMR group. There was no evidence of jaundice in the piglets and the livers appeared grossly normal in shape and color at necropsy. During the last week of feeding, serum bilirubin levels (total, direct and indirect), alanine aminotransferase and alkaline phosphatase were not different among treatment groups; however, aspartate aminotransferase in TPN pigs was significantly lower (30.5 U/L) than that in the SMR and PEN pigs (60.8 and 46.3 U/L, respectively). There was no histologic evidence of fat infiltration or cholestasis in any liver sections. Jejunal villous heights and crypt depths (Table 2) apparently recovered from the TPN-induced atrophy with 2 wk of milk refeeding, in that there were no differences among treatment groups. Ileal villous heights in TPN-treated piglets remained significantly less than those of SMR- and PEN-treated piglets and apparently had not completely recovered after 2 wk of refeeding. The jejunal and ileal mucosal disaccharidase activities (lactase, sucrase and maltase) were not different among treatment groups after 2 wk of milk refeeding. Discussion. Four weeks administration of TPN to piglets produces a small bowel (SB) disuse atrophy and is assumed to have occurred in this study (Remillard et al. 1998). However, the results of this study indicate that most of the parameters used to assess SB atrophy were not different from controls after 2 wk of oral refeeding of milk. Small or large intestinal weights or lengths, jejunal villus:crypt ratios and SB brush border enzyme activities had returned to normal with 2 wk of refeeding. Only one point in time of refeeding was evaluated, and therefore, no statement concerning the rate or pattern of SB morphologic recovery can be made. However, liver weights in TPN piglets remained significantly greater and ileal villous heights remained less compared with SMR piglets. This undesirable relationship between long-term parenteral feeding and hepatic changes has been recognized in humans and other species; it is thought to be multifactorial but is not yet well understood (Duerksen et al. 1996, Freund 1991). Small volume enteral feedings (PEN) in conjunction with parenteral therapy did ameliorate the ileal villous atrophy and hepatomegaly associated with TPN therapy because liver weights and ileal villous heights of partially enterally fed piglets were not significantly different from those of SMR piglets. There are definitive advantages to providing small enteral feedings (10% of energy) as an adjunct to parenteral therapy whenever clinically possible. Noncolostral milk has been shown to promote normal small intestinal morphology, increase gastric and intestinal weights, induce digestive enzyme activity and promote amino acid absorption equally as well as colostrum. Milk contains nutrients and growth factors (epidermal growth factor, transforming growth factor, insulin, insulin-like growth factor and lactoferrin), promotes gastric, duodenal and pancreaticobiliary secretions, and stimulates the release of systemic growth factors and hormonal stimulation, which are known to promote, individually and in concert, intestinal structure and function (Castillo et al. 1990). This study cannot determine which aspects of milk feeding promoted the intestinal recovery noted in TPN piglets, or the preservation of intestinal morphology in the PEN piglets. In summary, most aspects of intestinal disuse atrophy produced by 4 wk of NPO treatments in piglets were reversed when oral refeeding was reinstituted for 2 wk. In conclusion, feeding small volumes (2 mL/kg, twice daily by mouth) of a milk solution ameliorates some of the negative morphologic effects of NPO or TPN therapy, and therefore, would appear to be clinically beneficial in monogastric patients. [ABSTRACT FROM AUTHOR]

Using the Very Long Baseline Array, we have measured a trigonometric parallax for the microquasar GRS 1915+105, which contains a black hole and a K-giant companion. This yields a direct distance estimate of kpc and a revised estimate for the mass of the black hole of M☼. GRS 1915+105 is at about the same distance as some H II regions and water masers associated with high-mass star formation in the Sagittarius spiral arm of the Galaxy. The absolute proper motion of GRS 1915+105 is –3.19 ± 0.03 mas yr–1 and –6.24 ± 0.05 mas yr–1 toward the east and north, respectively, which corresponds to a modest peculiar speed of 22 ± 24 km s–1 at the parallax distance, suggesting that the binary did not receive a large velocity kick when the black hole formed. On one observational epoch, GRS 1915+105 displayed superluminal motion along the direction of its approaching jet. Considering previous observations of jet motions, the jet in GRS 1915+105 can be modeled with a jet inclination to the line of sight of 60° ± 5° and a variable flow speed between 0.65c and 0.81c, which possibly indicates deceleration of the jet at distances from the black hole ≳ 2000 AU. Finally, using our measurements of distance and estimates of black hole mass and inclination, we provisionally confirm our earlier result that the black hole is spinning very rapidly. [ABSTRACT FROM AUTHOR]