PubMed Health⌕ Search

Biomedical subjects

S F Kemp

Publications and source records attributed to S F Kemp.

At least 55 records · Page 3Linked to original sources
PubMed1985

Influence of manganese on growth, somatomedin and glycosaminoglycan metabolism.

Day-old chicks were fed control or manganese (Mn deficient diets ad libitum for 25 d. The chicks subsequently were refed control diet for up to 5 d. Mn deficiency significantly decreased growth rate and feed intake compared to controls. After 25 d of depletion, bone Mn concentration was 2% that of controls and 88% of the deficient chicks exhibited signs of perosis. Sulfate (35SO4) uptake into uronic acid was significantly depressed in cartilage from the Mn-depleted chicks and increased rapidly with refeeding, which may indicate increased glycosaminoglycan (GAG) biosynthesis or increased sulfation of the GAG molecule. In vitro activity of glycosyltransferases suggest that GAG synthesis may be interrupted by Mn deficiency. Somatomedin activity, serum insulin and glucose levels were not influenced significantly by Mn deficiency. Thus, while Mn deficiency decreased growth and GAG synthesis these effects were not mediated by somatomedin.

Animals↗
PubMed1984

Glycosylated albumin and transferrin: short-term markers of blood glucose control.

Serum was collected from children with type 1 diabetes mellitus before and 10 days after attending a camp session in which blood glucose concentrations were carefully controlled. Glycosylated and nonglycosylated proteins were separated, and levels of albumin and transferrin were determined on each of these fractions. Glycosylated hemoglobin was also determined and ranged from 4.6% to 14.6% (mean +/- SEM 8.1% +/- 0.2%). Mean initial glycosylated albumin in 73 children was 16.4% +/- 0.6%, which was elevated compared with the mean of levels in 20 nondiabetic controls (8.7% +/- 0.3%) and correlated well with levels of glycosylated hemoglobin (r = 0.71). After 10 days mean glycosylated albumin fell to 14.6% +/- 0.5% (P less than 0.00001), near the predicted final value of 13.4% if control had been ideal. Initial levels of glycosylated transferrin in 44 of these children ranged from 4.5% to 22.3% (11.4 +/- 0.6%) and was significantly higher than the mean of 3.8% +/- 0.3% in 20 nondiabetic controls. Mean final glycosylated transferrin fell to 8.2% +/- 0.3% (P less than 0.00001), near the predicted final mean of 7.0% +/- 0.2%. The mean of each subject's blood glucose determinations performed throughout the study period correlated with final levels of both glycosylated albumin (r = 0.55, P less than 0.001) and glycosylated transferrin (r = 0.54, P less than 0.001). Both glycosylated albumin and glycosylated transferrin appear to be reliable markers of short-term glycemic control; glycosylated transferrin (half-life 8 days) was more sensitive than glycosylated albumin over this 10-day period.

Adolescent↗
PubMed1984

Hormonal control of protein synthesis in chick chondrocytes: a comparison of effects of insulin, somatomedin C and triiodothyronine.

Somatomedin C (SM-C), insulin, and triiodothyronine (T3) each result in a 2-fold stimulation of incorporation of [125]leucine into protein by cultured chick sternal chondrocytes. Maximal stimulation occurred at concentrations of 12.5 X 10(-9) M SM-C, 11 X 10(-9) M insulin, and 1.5 X 10(-9) M T3. Submaximal concentrations of SM-C and T3 were additive in their effect, and together stimulated [125]leucine incorporated to a level greater than that achieved by either alone. Submaximal concentrations of SM-C and insulin were also additive in their stimulatory effect, but only to the level achieved by either alone. It was possible to demonstrate specific binding of [14C]SM-C to chondrocytes, and bound SM-C could be displaced by either unlabelled SM-C or insulin at concentrations similar to concentrations that stimulated protein synthesis. Actinomycin D abolished stimulation by T3, but not by insulin or SM-C. Thus, it appears that SM-C and insulin increase protein synthesis by stimulating the translational process after binding to the same receptor. T3 appears to act through a different mechanism, which requires stimulation of transcription.

Animals↗
PubMed1983

Acute effects of growth hormone administration: vitamin A and visceral protein concentrations.

We determined albumin, total protein, somatomedin C, retinol binding protein (RBP), transferrin, prealbumin, and complement (C3) concentrations in serum, and vitamin A concentrations in plasma before initiation of growth hormone (GH) therapy and 13 h after each of 4 daily injections of GH (0.1 U/kg) in 6 GH deficient children. Levels of total protein, albumin, and transferrin did not change during the first week of GH administration, however, transferrin levels rose after 6 weeks of GH therapy. Initial somatomedin C levels were below the normal range (0.19 +/- 0.03 U/ml), and rose with GH administration in 4 of the 6 subjects, resulting in a post-treatment mean of 0.56 +/- 0.23 U/ml. With GH administration vitamin A and RBP concentrations decreased from initial values (P less than 0.05), and reached a plateau after 2 injections of GH, while there was no change in concentrations of other proteins. There was a significant linear correlation (P less than 0.05) between the levels of vitamin A and RBP before and after GH administration. We conclude that GH administration results in a selective and marked reduction in the concentrations of plasma vitamin A and serum RBP.

Adolescent↗
PubMed1981

Acute somatomedin response to growth hormone: radioreceptor assay versus radioimmunoassay.

The acute somatomedin (SM) response to GH therapy has been examined in 21 GH-deficient children using a placental membrane radioreceptor assay (RRA) which measures a variety of SMs and a RIA specific for SM-C and insulin-like growth factor I (IGF-I). Plasma for determination of SM peptide content was obtained before initiation of therapy and 13 h after each of four daily injections of GH (0.1 U/kg). An additional SM determination was performed after 6 weeks of GH therapy (0.1 U/kg, three times per week) in seven of the subjects. RRA and RIA SM determinations were performed on the same acid-chromatographed sample and were compared to an acid-chromatographed pooled plasma standard. The 4 days of GH therapy resulted in an increase in SM levels from 0.39 +/- 0.24 to 1.18 +/- 0.62 (+/- SD) U/ml, determined by RIA. A single injection of GH resulted in a significant rise in plasma SM levels, measured by either RRA or RIA (P less than 0.001). Subjects who responded poorly to two injections of GH also had low SM levels after 4 days and even after 6 weeks of GH therapy. The RRA resulted in consistently higher value than the RIA. This difference was even greater when results were compared to a pure IGF-I/SM-C standard. The SM peptide contents determined by RRA and RIA were strongly correlated, not only for the group, but also among the determinations for each individual subject. However, the consistently higher values observed when the SM peptide content was measured by RRA compared to that measured by RIA and the variability in the RRA to RIA ratio among individual subjects suggest that the IGF-I/SM-C RIA measures only one of a number of GH-dependent SM peptides.

Adolescent↗
PubMed1981

In vivo modulation of somatomedin receptor sites: effects of growth hormone treatment of hypopituitary children.

We have previously demonstrated that somatomedin (SM) can induce the loss of specific SMC receptors on cultured IM-9 lymphocytes in a time- and concentration-dependent manner. To investigate the acute regulation of SM binding under in vivo conditions, we have evaluated SM receptors on circulating mononuclear cells obtained from 12 hypopituitary dwarfs before and after 4 days of human GH administration (0.1 U/kg . day). Plasma SM levels, measured by radioreceptor assay, rose from 0.37 +/- 0.08 U/ml (mean +/- SEM) to 1.00 +/- 0.10 (P less than 0.001). Concomitantly, specific binding of [125I]SMC to 50 x 10(6) mononuclear cells/ml fell from 13.61 +/- 0.97% to 10.40 +/- 0.85% (P less than 0.02). The decrease in specific binding was predominantly secondary to a reduced number of SMC receptor sites per cell, with no alteration in receptor affinity. Overall, a significant inverse correlation was observed between plasma SM levels and mononuclear cellular binding of [125I]SMC (P less than 0.001). The data demonstrate that treatment of hypopituitary dwarfs with conventional therapeutic doses of human GH results in significant acute increases in plasma SM levels in the majority of subjects, with a reciprocal decline in the specific binding of [125I]SMC. We conclude that SM, like insulin, is capable of regulating homologous receptor concentrations under both in vitro and in vivo conditions.

Child↗
PubMed1981

Plasma somatomedin-binding proteins in hypopituitarism: changes during growth hormone therapy.

The somatomedin (SM) peptides are carried in plasma complexed to specific SM-binding proteins (SMBPs). In addition to the SMBP in the complex, there is an unsaturated SMBP in plasma in which the SMBP is not occupied by SMs. We have compared levels of unsaturated SMBP in 7 normal adults to those in 21 children with GH deficiency before and during treatment with hGH (0.1 U/kg.day) for 4 days. In addition, the SM-C/insulin-like growth factor I (IGF-I) content of each plasma was measured by RIA. There was a significant (P less than 0.01) difference in unsaturated SMBP levels between normal controls (17.8 +/- 0.8% bound/20 microliters) and untreated hypopituitary patients (27.8 +/- 2.2% bound/20 microliters). Thus, a lower SM-C/IGF-I content was associated with a higher unsaturated SMBP level. Furthermore, there was a significant negative correlation between SM-C/IGF-I content and unsaturated SMBP in untreated hypopituitary patients (r = 0.73; P less than 0.0001). Treatment with hGH normalized the mean unsaturated SMBP level in hypopituitary patients within 2 days. Full displacement curves and Scatchard analysis showed that the increased unsaturated SMBP level in hypopituitary plasma was entirely due to an increased affinity (8.4 X 0.9 X 10(-10) M) compared to normal (2.3 X 0.2 X 10(-9) M). A higher affinity form of unsaturated SMBP is uniquely present in hypopituitarism and disappears with hGH treatment. The measurement of this unsaturated SMBP mirrors the SM peptide content.

Carrier Proteins↗
PubMed1981

Growth hormone and somatomedin in insulin-dependent diabetes mellitus.

In order to study the interrelationship of GH, somatomedin (SM), and growth in insulin-dependent diabetes mellitus (IDDM), concentrations of serum glucose, serum GH, and plasma SM were determined at 2-h intervals for 48 h in 19 ambulatory children with IDDM of at least 2-yr duration (mean duration, 6 yr) and in 9 normal age-matched controls. Serum glucose was significantly elevated (P less than 0.001) in subjects with IDDM compared to controls [287 +/- 15 mg/dl vs. 99 +/- 2 mg/dl (mean +/- SEM)] as was the hemoglobin A1C (11.0 +/- 0.40% vs. 4.59 +/- 0.08%) and the serum GH (8.4 +/- 0.4 ng/ml vs. 5.6 +/- 0.6 ng/ml; P less than 0.002). Despite evidence of inadequate diabetes control and elevated GH levels, the subjects with IDDM had normal SM levels (1.82 +/- 0.14 U/ml) compared to their age-matched controls (mean, 1.66 +/- 0.19 U/ml) and normal growth. Furthermore, SM levels did not show any significant diurnal variation in either group. There was no significant correlation in either group between the mean plasma SM concentrations and the mean serum GH or mean serum glucose concentration of each subject. These findings of normal SM levels and elevated GH levels in these children with normal stature and IDDM suggest a partial block in GH action.

Adolescent↗
PubMed1980

The action of somatomedin on glycosaminoglycan synthesis in cultured chick chondrocytes.

A basic somatomedin preparation results in a 2-fold stimulation of incorporation of both [3H]leucine into protein and 35SO4 into glycosaminoglycans by cultured chick sternal chondrocytes. The stimulation is seen in the presence of 20 mM 4-methylumbelliferyl-beta-D-xyloside alone but is not observable in the presence of both xyloside and cycloheximide, indicating that the stimulation by somatomedin is dependent on protein synthesis. Somatomedin stimulates incorporation of leucine into glycosaminoglycans to the same extent to which it stimulates incorporation of sulfate into glycosaminoglycans, suggesting involvement of core protein synthesis. In the presence of the xyloside, however, there is stimulation of synthesis of glycosaminoglycan chains initiated on the xyloside, with a shift in molecular weight distribution to larger molecular weights. Thus, when core protein is not rate limiting, a more general stimulatory effect of somatomedin is observed.

Animals↗
PubMed1976

Biosynthesis of glycosphingolipids in cultured mouse neuroblastoma cells. Precursor-product relationships among sialoglycosphingolipids.

The reaction sequence for the biosynthesis of gangliosides by mouse neuroblastoma cells has been investigated by studying the pattern of incorporation of labeled precursors into sialoglycosphingolipids. Cultured NB41A cells incorporated N-[3H]acetylmannosamine into the sialic acid moiety of GM3 in less than 10 min. Labeled GM2 was not detected in cells incubated for less than 30 min, while measurable radioactivity did not appear in GM1 until after 60 to 90 min. Analogous experiments were carried out using [14C]galactose. No significant amount of labeled hexose was incorporated into asialo-GM2 during 60 min of culture. These studies are in accord with results of previous studies on glycosyltransferases of NB41A cells (Kemp, S. F., and Stoolmiller, A. C. (1976), J. Neurochem. 26, 723-732), and further support the concept that the pathway of synthesis of gangliosides proceeds via GM3 leads to GM2 leads to GM1.

Animals↗
PubMedDate not supplied

Comparison of Visidex and Chemstrip bG with Beckman Glucose Analyzer determination of blood glucose.

Chemical test strips for estimating blood glucose have been shown to be reliable, rapid, and convenient when properly used. This study compares a new product, the Ames Visidex (Miles Laboratories, Elkhart, Indiana), and an established product, the Bio-Dynamics Chemstrip bG (Boehringer-Mannheim, Indianapolis, Indiana) with plasma glucose as measured by standard laboratory methods. Determination of blood glucose by visual inspection of both chemical strips gave an estimation of true plasma glucose in the hypoglycemic and euglycemic ranges. Both strips were reliable in predicting those values that were hyperglycemic (greater than 180 mg/dl).

Blood Glucose↗