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Biomedical subjects

S B Smith

Publications and source records attributed to S B Smith.

At least 199 records · Page 11Linked to original sources
PubMed1984

Metabolic responses to fasting and alloxan-induced diabetes mellitus in steers.

To induce diabetes mellitus in 8 steers, they were fasted for 96 hours and given 110 mg of alloxan/kg of body weight (IV, in 1 dose) immediately before refeeding. Subsequently, 4 of the steers were treated with insulin (0.1 to 3 U/kg) to control hyperglycemia and 4 were not given insulin. Four control steers were fasted and refed. Fasting increased serum phosphorus, total protein, and bilirubin and decreased serum magnesium and potassium. Refeeding returned serum values of magnesium, potassium, total protein, and bilirubin toward base-line values, regardless of treatment group. However, serum phosphorus remained increased in steers with alloxan-induced diabetes and was not lowered by insulin injections. Sodium and chloride values were depressed in steers with alloxan-induced diabetes; these values remained significantly (P less than 0.05) lower than base-line values, even in steers given insulin. Fat infiltration was evident in the pancreas, liver, and to some extent, kidneys of steers with alloxan-induced diabetes, but was occasionally present in tissues of steers given insulin.

Animals↗
PubMed1983

Phosphorylation by cyclic GMP-dependent protein kinase of a synthetic peptide corresponding to the autophosphorylation site in the enzyme.

The substrate specificity of cGMP-dependent protein kinase has been investigated by examining the ability of the enzyme to phosphorylate a series of synthetic peptides that correspond to the amino acid sequence at its site of autophosphorylation. The undecapeptide Ile53-Gly-Pro-Arg-Thr-Thr58-Arg-Ala-Gln-Gly-Ile63 which corresponds to the sequence around threonine-58 in cGMP-dependent protein kinase (Takio, K., Smith, S.B., Walsh, K.A., Krebs, E.G., and Titani, K. (1983) J. Biol. Chem. 258, 5531-5536) was synthesized and tested as a substrate for that enzyme. It was phosphorylated to the extent of 1.0 mol of phosphate/mol of peptide. Analysis of the products of Edman degradation of the phosphopeptide indicated that only threonine-58 was phosphorylated, as is the case for the autophosphorylation reaction in the native enzyme. The peptide was phosphorylated by cGMP-dependent protein kinase with a Km value of 578 +/- 25 microM and a Vmax of 0.069 +/- 0.003 mumol/min/mg of enzyme. This low Vmax value is consistent with the relatively slow rate of the autophosphorylation reaction. An analog peptide that contained serine in place of threonine-58 was also phosphorylated to 1.0 mol of phosphate/mol of peptide. That phosphopeptide contained only phosphoserine. The serine-containing analog peptide had a Km value similar to that of the parent peptide but was phosphorylated with a 70-fold higher Vmax value. Substitution of arginine-56 in the parent peptide by an alanine residue resulted in a peptide that was essentially not a substrate. Substitution of arginine-59, COOH-terminal to the phosphorylatable threonine, yielded a peptide with a Vmax similar to that of the parent peptide but a Km value of almost 22,000 microM. These results indicate that serine is a better phosphate-accepting residue than is threonine and that both arginine residues around the site of autophosphorylation are important specificity determinants for the cGMP-dependent protein kinase.

Amino Acid Sequence↗
PubMed1983

Amino acid sequence around a "hinge" region and its "autophosphorylation" site in bovine Lung cGMP-dependent protein kinase.

An exposed "hinge" region of cGMP-dependent protein kinase is known to be susceptible to both limited proteolysis and autophosphorylation. A 91-residue fragment has been isolated from this region and its amino acid sequence has been compared with the analogous regions of the cAMP-dependent protein kinases. Although a resemblance among these sequences is not striking, the phosphorylation sites are in corresponding regions toward the NH2 termini, and there are indications of homology in the vicinity of their autophosphorylation sites. As in the cAMP-dependent protein kinase, the site of autophosphorylation and the site of susceptibility to limited proteolysis are very near each other in the primary structure. The actual site of autophosphorylation (the underlined threonine residue in Pro-Arg-Thr-Thr-Arg) is quite different from those in the regulatory subunit of Type II cAMP-dependent kinase or the site in Type I regulatory subunit that can be phosphorylated by the cGMP-dependent protein kinase.

Amino Acid Sequence↗
PubMed1983

Histologic correlation of transplant rejection diagnosed by computer-assisted sulfur colloid scan.

Sulfur colloid scanning has been suggested as a means of early detection of renal transplant rejection. Visual interpretation of increased uptake by the allograft as opposed to surrounding pelvic structures was taken to signify rejection. In an attempt to increase the accuracy of these scans we programmed a computer to do differential counts between graft and surrounding pelvis and to then calculate a ratio. Hopefully this mathematical determination of increased uptake would be more accurate. These scans were compared with simultaneously obtained biopsy material. Unfortunately, the false negative and false positive rates were too high to make sulfur colloid useful in predicting graft rejection. Finally, our data showed that an early positive scan did not predict long-term outcome as had been suggested by others.

Diabetes Complications↗
PubMed1983

Interrelationships between insulin and lipid metabolism in normal and alloxan-diabetic cattle.

Three experiments were performed to elucidate the role of insulin in regulating adipose tissue lipogenesis and lipolysis in the bovine. First, 4-day fasted steers were injected with 110 mg/kg alloxan on the day of refeeding; half the group received sufficient insulin to maintain near-normal blood glucose levels. Biopsy samples of subcutaneous adipose tissue were obtained throughout this and subsequent experiments. Insulin therapy increased the incorporation of 14C-labeled substrates into fatty acids, but was not necessary to increase lipogenic enzyme activities to control values. Steers in the second experiment were not fasted prior to alloxan injection (60 mg/kg). Seven days after alloxan treatment, the animals were injected with insulin, while a control group was pair-fed to the level of intake observed for the alloxan-treated steers during the first 7-day period. Whereas alloxan treatment decreased, and insulin therapy increased substrate incorporation and lipogenic enzyme activities, these effects were more closely correlated with levels of feed intake than with insulin levels. Alloxan treatment increased the basal but not the stimulated lipolytic rate in adipose tissue, and insulin treatment depressed the increased rate of lipolysis, as reflected in the plasma levels of free fatty acids and triglycerides. In the third experiment, one group of steers was injected with 1-6 U/kg of insulin, while a second group received insulin injections plus glucose infusions (125.3 mmol/hour). Increases in substrate incorporation and the activity of acetyl CoA carboxylase were observed in the insulin plus glucose-infused steers, but not in those animals receiving insulin alone. There were no effects of insulin or glucose plus insulin treatment on basal or stimulated lipolytic rates. The results of this study suggest that circulating insulin levels do not influence in vivo rates of lipogenesis in the bovine animal to the degree observed in the laboratory rat.

ATP Citrate (pro-S)-Lyase↗
PubMed1983

Role of insulin in regulating amino acid metabolism in normal and alloxan-diabetic cattle.

Experimental diabetes was induced in the bovine in two experiments by intravenous injection of alloxan (110 mg/kg or 60 mg/kg) in order to determine the role of insulin on nitrogen and amino acid metabolism. In experiment 1, insulin was injected to control hyperglycemia in one group of steers immediately after alloxan treatment (110 mg/kg). In experiment 2, insulin was injected beginning 6 days following alloxan treatment (60 mg/kg) to control hyperglycemia. Plasma glucose increased to 800-1400 mg/100 ml within 5-6 days following alloxan administration (experiment 1). A large surge of insulin release occurred immediately after alloxan administration, which was followed by a decrease in insulin concentrations to subnormal levels in those animals not treated with insulin. Alloxan-treated steers became acidotic by day 2 as indicated by a drop in blood pH, bicarbonate and base excess. Acid-base status improved in steers treated with alloxan plus insulin but did not return to normal. Alloxan treatment caused a marked increase in serum urea-N and creatinine concentrations and insulin treatment of the alloxanized animal decreased both serum urea-N and creatinine concentrations. Treatment with alloxan caused a two- to threefold increase in the plasma concentrations of valine, isoleucine, leucine, lysine and 3-methylhistidine and a decrease in alanine, threonine, citrulline and arginine. Insulin treatment of the alloxanized bovine maintained normal plasma concentrations of valine, isoleucine and leucine. In a third experiment, the injection of insulin (6 U/kg) into normal cattle caused a transient decline in plasma concentrations of branched-chain amino acids (BCAA); however, if glucose was continuously infused (125 mmol/hour) in addition to insulin injection, a sustained decrease in plasma BCAA concentrations was observed. These data support the concept that insulin promotes decreased plasma concentrations of BCAA either by promoting tissue anabolism by stimulating tissue uptake and protein synthesis or decreasing proteolysis and BCAA release.

Amino Acids↗
PubMed1983

Acute renal failure with hypocreatininemia in Guillain-Barré syndrome.

A 68-year-old woman with Guillain-Barré syndrome had profoundly depressed serum creatinine concentration and 24-hour urinary creatinine excretion despite maintenance of her weight by hyperalimentation. Because of hypocreatininemia, the development of aminoglycoside-induced acute renal failure was initially missed. A retrospective study of seven patients with Guillain-Barré syndrome who were treated with hyperalimentation to maintain nutritional status showed a significant decrease in serum creatinine concentration but no significant decline in weight or blood urea nitrogen level. Because the serum creatinine is decreased in patients with Guillain-Barré syndrome, caution must be exercised in using serum creatinine determination as an estimate of glomerular filtration rate.

Acute Kidney Injury↗
PubMed1983

Patient concepts and misconceptions about acne.

A questionnaire was completed by 178 patients and relatives with dermatologic conditions as the first phase of a two-part study of the interrelationships between understanding and treatment compliance. Substantial numbers of those surveyed had ideas about cause, treatment, and prognosis that might adversely affect therapy. Diet, dirt, soap and water, topically applied acne gels, and realistic expectations for cures seem to be the most important subjects to emphasize in the written or oral "teaching" of patients with acne.

Acne Vulgaris↗
PubMed1983

Spontaneous pneumothorax. Special considerations.

A review of patients with spontaneous pneumothorax treated at Tripler Army Medical Center (TAMC) between 1977 and 1979 was undertaken to identify areas of strength 1977 and 1979 was undertaken to identify areas of strength and areas of weakness. Fifty patients with a total of 58 pneumothoraces were identified, and their charts were reviewed. Fifty-one pneumothoraces were classified as primary or idiopathic, and seven were secondary to parenchymal disease. Problem areas that were identified included failure to consider catamenial pneumothorax in the differential diagnosis of spontaneous pneumothorax and failure to recognize reexpansion pulmonary edema as a complication of treatment.

Adolescent↗
PubMed1982

The effect of 3-mercaptopicolinic acid and substrate interactions on the incorporation of lipogenic precursors into glyceride-glycerol, glyceride-fatty acids and nonesterified fatty acids in bovine adipose tissue.

The effects of 3-mercaptopicolinic acid, an inhibitor of phosphoenolpyruvate carboxykinase, were studied in bovine subcutaneous adipose tissue slices in vitro. Lactate and glucose stimulated the incorporation of [U-14C]acetate into total lipids and nonesterified fatty acids. 3-Mercaptopicolinic acid abolished the stimulatory effect of lactate on total synthesis but had no effect on that from glucose. The inhibitor decreased glyceride-glycerol and glyceride-fatty acid synthesis from L-[U-14C]lactate by 90 and 30%, respectively; glyceride-glycerol synthesis from D-[U-14C]glucose was refractory to inhibition by 3-mercaptopicolinic acid, whereas the inhibitor tended to increase glyceride-fatty acid synthesis from glucose. The presence of lactate plus glucose in the incubation media elicited a greater than additive stimulation of acetate incorporation into total lipids. Glucose doubled the incorporation of lactate into glyceride-fatty acids, but had no effect on the net incorporation of lactate into nonesterified fatty acids. Lactate, but not glucose, stimulated the incorporation of [1-14C]palmitate into glyceride-fatty acids; 3-mercaptopicolinic acid increased this rate for all substrate combinations studied, although this was opposite to expected results. As determined with 3H2O, lactate and glucose stimulated the synthesis of total lipids, and 3-mercaptopicolinic acid decreased the stimulatory effects of lactate and glucose on 3H2O incorporation. The results suggest that lactate, and possibly glucose, stimulate the incorporation of acetate into fatty acids by increasing the availability of alpha-glycerophosphate.

Adipose Tissue↗
PubMed1982

Primary structure of the regulatory subunit of type II cAMP-dependent protein kinase from bovine cardiac muscle.

The complete amino acid sequence of the regulatory subunit of type II cAMP-dependent protein kinase from bovine cardiac muscle is presented. Primary fragments for the sequence determination were obtained by limited proteolysis with various proteases or by cleavage with cyanogen bromide. The sequence of the 400 amino acid residues has two homologous regions, strongly suggesting tandem gene duplication. The predicted secondary structure suggests the presence of 42% alpha-helix, 23% beta-strand, and 23 beta-turns. The molecular weight of the subunit, as derived from the sequence, is 45,084 including a phosphate group at residue 95. This is significantly less than earlier estimates based on NaDodSO4 gel electrophoresis and sedimentation experiments. The structure is discussed in terms of putative sites of interaction with cAMP and with the catalytic subunit.

Amino Acid Sequence↗
PubMed1982

Hormonal effects on partitioning of nutrients for tissue growth: role of insulin.

Understanding factors that potentially regulate pathways of nutrient utilization is essential to the development of means of manipulating tissue growth to optimize the type and quality of product produced. Insulin is one hormone that has pronounced effects on carbohydrate and protein metabolism. Relative to most monogastric animals, ruminants absorb little glucose directly from the gastrointestinal tract. Therefore, it might be expected that insulin would have a less important role in regulating glucose and carbohydrate metabolism in the ruminant animal. Effects of insulin on lipogenesis and lipolysis both in vitro and in vivo in the ruminant appear to be small. Insulin may promote lipid deposition by increasing adipocyte membrane permeability to glucose with subsequent metabolism to alpha-glycerolphosphoric acid and thereby stimulating fatty acid esterification. Insulin also stimulates adipose lipoprotein lipase, which would increase the supply of fatty acids for esterification in adipose tissue. Insulin appears to indirectly alter hepatic glucose production by decreasing the release of gluconeogenic precursors from peripheral tissues. The known effects of insulin on lipid and carbohydrate metabolism have tended to direct attention away from protein metabolism, a process on which insulin may have a more significant role in the ruminant. Insulin or insulin and glucose have marked effects on regulating plasma levels of branched-chain amino acids, presumably by promoting their uptake or by decreasing their catabolism by muscle tissue. More information is needed to fully understand the role of insulin in regulating muscle protein metabolism.

Adipose Tissue↗
PubMed1982

Abdominal trauma: the limited role of peritoneal lavage.

Abdominal trauma was reviewed in 103 cases: 88 (85%) resulted from blunt trauma and 15 (15%) from penetrating trauma. Of the 88 cases of blunt abdominal trauma, 22 were felt to have significant intra-abdominal injuries on clinical evaluation alone. On exploration, 20 (91%) had significant injuries, one had a trivial injury, and one had negative exploration. Peritoneal lavage was performed on 66 of the 88 cases of blunt trauma. The results were positive in 36 cases. On exploration, 23 had significant injuries, nine had trivial injuries, and four had negative laparotomies. Twenty-eight lavages were negative; 26 were managed successfully without exploratory laparotomy, but two had significant injuries. Two patients had insignificant return from peritoneal lavage; both had positive laparotomies. Fourteen of 15 patients with penetrating abdominal trauma were managed by exploratory laparotomy and one was observed after negative lavage. Five of six patients explored for gunshot wounds had significant injuries. Of the eight patients explored for stab wounds, only two had significant injuries.

Abdominal Injuries↗