Biomedical subjects

P K Wirdnam

Publications and source records attributed to P K Wirdnam.

8 recordsLinked to original sources

PubMed1987

Somatomedin-C in human fetal pancreas. Cellular localization and release during organ culture.

The presence of somatomedin-C/insulin-like growth factor I (SM-C/IGF-I) was investigated in human fetal pancreatic glands obtained after prostaglandin-induced abortion at 14-17 wk of gestation. Pancreatic explants were cultured in medium containing 11.1 or 22.2 mM glucose and 20% fetal calf serum for 8-10 days. During this period they were exposed, on two separate occasions, to serum-free culture medium for 24 h. SM-C/IGF-I and insulin were measured radioimmunologically in the serum-free media and in acid-ethanol-extracted homogenates of the cultured explants. SM-C/IGF-I was measurable in the conditioned media only after extraction by reverse-phase chromatography to remove somatomedin-binding proteins. On gel filtration at neutral pH of extracted medium samples, the immunoreactive SM-C/IGF-I was recovered in the region of the homogeneous peptide with an apparent molecular weight of 7000-8000. Explants cultured in 22.2 mM glucose contained more SM-C/IGF-I and had a tendency to release more of the peptide into the culture medium than explants cultured in 11.1 mM. There was no difference in insulin content or release between the two groups. By immunocytochemistry, SM-C/IGF-I was localized to the beta-cells of the endocrine pancreas in both freshly fixed tissue and cultured explants. We conclude that the human fetal pancreas contains SM-C/IGF-I and secretes the peptide during tissue culture. The presence of SM-C/IGF-I in the islets of Langerhans may contribute to the growth and development of the insulin-producing beta-cell.

Adult↗

PubMed1985

Radioimmunoassay for serum and urinary Tamm-Horsfall glycoprotein in the rat.

Rat Tamm-Horsfall glycoprotein (THG) was isolated from urine and disaggregated by gel filtration. Purity was confirmed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and autoradiography. Antibodies were raised and used in the development of a specific radioimmunoassay for rat THG. Parallelism could be demonstrated between the standard preparation and urine (diluted to 1:320 with distilled water) and serum (at all dilutions) samples. Recovery of standard added to urine or serum was on average 93% and inter- and intra-assay variation were both below 7%. There was a positive correlation between the mean urinary excretory rate of THG (microgram/24h) and body weight in female rats (p less than 0.001) but not in male rats. Serum THG levels were similar in both sexes and showed a positive correlation with body weight (p less than 0.001; range 43-240 ng/ml). It is concluded that the rat urinary THG excretion rate is similar to that in man and that rat serum also contains a THG-like protein.

Animals↗

PubMed1984

Tamm-Horsfall glycoprotein release from rat kidney cortex slices in vitro.

Rat kidney cortex slices were incubated for 30 min at 37 degrees C in unmodified Krebs-Henseleit buffer containing aldosterone, vasopressin, theophylline, ethacrynic acid, frusemide, spironolactone or ouabain. Tamm-Horsfall glycoprotein (THG) released into the media was measured by radioimmunoassay and at the end of each experiment the slices were homogenized and assayed for THG content. Incubation of kidney cortex slices in unmodified buffer resulted in a significant increase in the slice THG content when compared with pre-incubation levels. The increase was prevented by puromycin or cycloheximide. Incubation in ethacrynic acid (1 mmol/l) or frusemide (10 mmol/l) resulted in a significant increase in release of THG when compared with unmodified buffer. Puromycin or cycloheximide failed to prevent the increased release. THG release induced by ethacrynic acid or frusemide is probably the result of an aggregation-disaggregation reaction on the cell membrane. It is suggested that the action of the chloride inhibiting diuretics, ethacrynic acid and frusemide, is mediated in some way via THG.

Animals↗

PubMed1983

Pancreatic endocrine cell fractions in erythroblastosis fetalis.

Pancreatic sections from 21 cases of rhesus disease and 20 control newborn infants of 30--40-wk gestational age were stained by the immunoperoxidase method for insulin, glucagon, somatostatin, and pancreatic polypeptide (PP). The fractional area occupied by each cell type was estimated, taking note of whether the gland contained PP-rich (ventral lobe) or PP-poor islets (dorsal lobe). In the PP-rich part of the pancreas, the volume fraction of all four endocrine cell types was significantly greater in the rhesus cases than in the controls. No difference was found between the two groups in the PP-poor part of the gland. The results show that abnormal development of the PP-rich part of the pancreas occurs in erythroblastosis fetalis. The localization of the changes to one part of the pancreas may explain some of the earlier conflicting reports on this topic.

Erythroblastosis, Fetal↗

PubMed1982

The pancreatic beta cell fraction in children with errors of amino acid metabolism.

Blocks of pancreas were obtained from the following cases of errors of amino acid metabolism: eight cystinosis, eight tyrosinosis, five phenylketonuria, three hypermethioninemia, two hyperprolinemia and two maple syrup urine disease. Blocks were also obtained from four cases of homocystinuria and 72 control patients of the same age range who had died from a variety of conditions believed not to affect the pancreas. Sections were cut from each pancreatic block and stained with haematoxylin or for insulin and pancreatic polypeptide (PP) by the immunoperoxidase method. Measurements were performed separately in the PP rich and the PP poor regions of all sections. The fractional surface area of section occupied by insulin stained cells (%) and the cellular density (nuclei/100 microgram2) of each specimen were estimated. The beta cell fractional area in the PP poor region of the experimental cases was plotted against the logarithm of gestational age and compared to a reference grid of the 10th, 50th and 90th centile estimates of the control cases (Fig. 1). The distribution of results from the cases of tyrosinosis, phenylketonuria and cystinosis were skewed positively; four of eight tyrosinosis and three of five phenylketonuria cases lying above the 90th centile (P less than 0.001). The beta cell fractional area of the cystinosis cases was also significantly increased (Table 1, P less than 0.05). The results from the cases dying from maple syrup urine disease, hyperprolinemia, hypermethioninemia or homocystinuria were distributed as might be expected to occur by chance.

Amino Acid Metabolism, Inborn Errors↗

PubMed1981

Quantitation of the B and A cell fractions in human pancreas from early fetal life to puberty.

The morphological development of B and A cells in human pancreas was studied with immunoperoxidase strains in 172 cases ranging in age from 12 weeks of fetal life to puberty. Tissue was defined as polypeptide rich or poor to take account of the known islet heterogeneity in the gland. Pancreatic cell density was measured and B and A cell development was calculated in terms of (a) volume fraction and (b) density (micron2/100 nuclei). B cell density increased throughout fetal life to reach a peak at the postnatal age of 2 months, whereas A cell density was greatest in the 6 month fetus. The ratio of B to A cell volume fractions is approximately 1.5 throughout most of fetal life and rises postnatally to a stable value of 5 by the age of 2.5 years.

Adolescent↗

PubMed1981

Quantitative morphology of B, A, D, and PP cells in infants of diabetic mothers.

Pancreatic specimens from 34 infants of diabetic mothers (IDM) and 32 control infants of gestational ages 26-44 wk were examined histologically using immunocytochemical stains for insulin, glucagon, somatostatin, and pancreatic polypeptide (PP). Each section was divided into PP-rich and PP-poor regions that are thought to be derived from the ventral and dorsal lobes of the gland, respectively. In some of these, the fractional area (%) occupied by positively stained B, A, and PP cells was determined by automatic image analysis, and the area occupied by D cells was determined by conventional point counting. The B cell fractional area was significantly higher in the IDM in both PP-poor and PP-rich areas (P less than 0.02). the fractional area of A cells in PP-poor areas and of PP cells in PP-rich areas was also significantly greater in IDM (P less than 0.02). The total endocrine cell fractional area was significantly greater in IDM in PP-poor but not in PP-rich regions of the pancreas. These results are not compatible with the hypothesis that maternal hyperglycemia results in specific fetal B cell hyperplasia and raise the possibility that hyperplasia of B, A, and PP cells in IDM may result from a variety of stimuli or that one stimulus acts on a pluripotential stem cell.

Female↗

PubMed1977

Hypoglycin stimulates insulin secretion.

Hypoglycin A(0.01--1.0 mmol/l) stimulated insulin release from pieces of rabbit pancreas in vitro in the presence or absence of extracellular glucose. The relevance of this finding to the hypoglycaemia of Jamaican vomiting sickness is discussed.

Animals↗