Statistical quality control of radioimmunoassays.
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Analysis of Variance↗
Biomedical subjects
P L Rayford
Publications and source records attributed to P L Rayford.
Luteinizing hormone activity in plasma during the menstrual cycle.
Daily determinations of luteinizing hormone activity in plasma throughout a menstrual cycle in ten young women showed a sharp peak of activity lasting less than 48 hours around midcycle and higher mean values during the follicular phase than during the luteal phase in nine instances.
Adult↗
Radioimmunoassay for luteinizing hormone in human plasma or serum: physiological studies.
It is not practical to quantitate gonadotropin in the blood of normal men and women by utilizing bioassays. We have developed a method for sensitive, precise, and specific radioimmunoassay of luteinizing hormone (LH) in human serum or plasma. Antisera were developed against human chorionic gonadotropin, and one of these was selected for extensive cross-reaction with human LH. Highly purified LH was radioiodinated by the method of Greenwood, Hunter, and Glover. Separation of antibody-bound from free LH-(131)I was accomplished by a double antibody technique. Dose-response curves for the purifed LH, an impure urinary LH preparation, pituitary powder, and LH in plasma were all identical. Immunoassay and bioassay of impure urinary and pituitary gonadotropin preparations in terms of a common standard resulted in an index of discrimination of close to unity. LH levels in plasma from 32 adult men and 30 women outside the midcycle ranged from 0.6 to 3.2 mmug per ml (1 mmug of our laboratory LH standard is equivalent to 8 mU of the Second International Reference Preparation of Human Menopausal Gonadotropin). Levels were remarkably constant in men from day to day and in women except at midcycle, when a sharp peak occurred lasting less than 24 hours. In all women studied who had a midcycle LH peak, mean plasma LH levels during the follicular phase of the menstrual cycle were higher than mean values obtained during the luteal phase. Prepubertal children had detectable plasma LH, and mean values were only slightly less than in adults. Plasma from castrate men or women or postmenopausal women contained 4.5 to 10.5 mmug per ml. Clomiphene treatment of four men resulted in a doubling of plasma LH in 5 days.
Biological Assay↗
Effect of pyrogen on blood levels of pituitary trophic hormones. Observations of the usefulness of the growth hormone response in the detection of pituitary disease.
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17-Hydroxycorticosteroids↗
Simplified, partially automated method for radioimmunoassay of human thyroid-stimulating, growth, luteinizing, and follicle stimulating hormones.
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Autoanalysis↗
Radioimmunoassay for human luteinizing hormone.
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Chorionic Gonadotropin↗
Effect of synthetic porcine gastrin-releasing peptide on plasma levels of immunoreactive cholecystokinin pancreatic polypeptide and gastrin in dogs.
This study was conducted to determine if synthetic porcine gastrin-releasing peptide (GRP) stimulates the release of immunoreactive cholecystokinin (CCK), pancreatic polypeptide (PP) and gastrin in dogs. Three doses (0.01, 0.1 and 0.5 micrograms/kg-hr) of synthetic porcine GRP were administered intravenously to six conscious dogs. Synthetic porcine GRP stimulated the release of each hormone in a dose-related manner. The effect of GRP on the response of gastrin was greater than its effect on CCK and PP responses. This study indicates that the biological action of synthetic porcine GRP is similar to the bombesin, an amphibian peptide shown previously to stimulate the release of gastrointestinal peptides.
Animals↗
Ileo-caecal resection induced pancreatic growth in rats.
The effect of ileo-caecal resection on pancreatic growth was studied in rats four weeks after the operation. The results were compared with an identical control group who had undergone laparotomy alone. Pancreatic wet weight in ileo-caecal resectioned rats was 1.4 times greater than that found in control rats. Protein, DNA, RNA contents in the pancreas, pancreatic wet weight per 100 micrograms DNA and RNA/DNA ratio were also found significantly elevated in experimental group as opposed to the control group. Basal plasma levels of cholecystokinin (CCK) and gastrin were measured to delineate the influence of hormonal response on the pancreatic growth in ileo-caecal resected rats and were found not significantly increased after ileo-caecal resection. The data suggest that the enlargement of pancreas in ileo-caecal resected rats may be due to hyperplasia and hypertrophy of pancreatic cells; alternatively, the pancreatic growth may have been influenced by the bile acid deficiency and the reduction or release of an inhibitory factor present in the ileum of rats.
Aging↗
Effect of nicotine on basal and bombesin stimulated canine plasma levels of gastrin, cholecystokinin and pancreatic polypeptide.
The influence of nicotine on the basal and bombesin (BBS) stimulated plasma levels of gastrin, cholecystokinin (CCK) and pancreatic polypeptide (PP) was investigated in conscious dogs. Plasma levels of nicotine and gastrointestinal (GI) hormones were measured by employing gas liquid chromatography and specific radioimmunoassay (RIA). The basal levels of gastrin, CCK and PP were found to be in pg/ml (pmol/l) (mean +/- S.E.), 28 +/- 5 (13 +/- 3), 252 +/- 32 (66 +/- 8) and 347 +/- 136 (83 +/- 32), respectively and these values remained unchanged with nicotine. Significant increases in levels of gastrin, CCK and PP were, however, found with infusions of BBS alone or with BBS in combination with nicotine. Gastrin levels were higher whereas CCK and PP levels were lower with BBS alone than with BBS plus nicotine. The peak values for CCK and PP, but not gastrin, were less during second BBS infusion. These results indicate that nicotine, in presence of bombesin, has an inhibitory effect on the release of gastrin and a stimulatory effect on the release of PP and CCK.
Animals↗
L364718, a new CCK antagonist, inhibits biological actions of CCK in conscious dogs.
The effects of L364718, a new CCK receptor antagonist, on CCK-8 stimulated pancreatic secretion and PP release were examined in three conscious dogs with pancreatic fistulas. L364718 (20 nmol/kg) caused a potent inhibition of CCK-8 stimulated pancreatic protein, amylase and trypsin secretion but not of volume and bicarbonate secretion. Release of PP by CCK was also significantly suppressed by L364718. The degree of inhibition by L364718 was dependent upon the amount of CCK-8 infused. This study demonstrates that L364718 acts as a potent antagonist of CCK's action on pancreatic enzyme secretion and PP release in dogs and suggests that this agent might be a useful tool for studying the physiological role of CCK in conscious animals.
Animals↗
Pentagastrin-stimulated DNA synthesis in mouse gut is influenced by the circadian system.
Gastrin is trophic for rodent gut mucosa. Proglumide, a competitive inhibitor of gastrin, can exert an antitrophic effect and can block pentagastrin-stimulated DNA synthesis. We have examined the influence of the circadian system on pentagastrin-stimulated DNA synthesis in the murine stomach (glandular and nonglandular stomach) and colon. We studied 224 male CD2F1 mice divided into four groups. Group A was ad lib fed (controls). Groups B, C, and D received 6-9 intraperitoneal injections of either NaCl, pentagastrin or pentagastrin + proglumide, at 8-h intervals prior to sacrifice. Mice from each group (A-D) were killed (by cervical dislocation) at 3-h intervals for 24 h. Incorporation of tritiated thymidine (DNA synthesis) was measured, and significant (p less than 0.001) circadian rhythms were found, which were not eliminated after treatment with either pentagastrin or pentagastrin + proglumide. DNA synthesis in the glandular stomach increased significantly after treatment with pentagastrin , but only during the span of time when DNA synthesis was increasing also in control mice; it had no effect at other times. Proglumide blocked the effect of pentagastrin only during the time of increasing DNA synthesis; it had no effect at other times. The identical regimen given at different times in the circadian cycle yielded significantly different results. In the intact animal, studies on the effects of various stimulators or inhibitors of DNA synthesis should be time-qualified.
Animals↗
Effects of synthetic human pancreastatin on pancreatic secretion and blood flow in rats and dogs.
Effects of synthetic human pancreastatin-52 and human pancreastatin-29 on pancreatic secretion and blood flow were examined in rats and dogs. Synthetic human pancreastatin-52 and human pancreastatin-29 were equally potent in suppressing the release of amylase stimulated by cholecystokinin in rats in vivo. However, neither human pancreastatin-52 nor human pancreastatin-29 altered basal and cholecystokinin-stimulated amylase release from isolated dispersed rat pancreatic acini. In studies in dogs, human pancreastatin-29 suppressed releases of amylase and protein stimulated by cholecystokinin, but did not alter pancreatic blood flow. These results suggest that the inhibitory effects of pancreastatin on pancreatic secretion do not involve a direct action on pancreatic acinar cells nor alteration of pancreatic blood flow. Pancreastatin probably is important in regulating exocrine pancreatic secretions as well as endocrine pancreatic secretions.
Amylases↗
Alteration in gastrointestinal peptides after thermal injury in humans.
Alterations in gastrointestinal function are common after thermal injury in humans. The peptide hormones gastrin and cholecystokinin are known to exert effects on gastric and biliary motility and on secretory function and to induce trophic changes in gut mucosa. The effect of injury on these hormones has received little attention. Six patients with burns were studied while receiving a combination of regular diet and continuous enteral feeding. Four healthy members of the nursing staff served as the control group. Blood was drawn every 4 hours for 24 hours. Gastrin and cholecystokinin were analyzed by radioimmunoassay. Patients with burns demonstrated significantly higher levels of gastrin and lower levels of cholecystokinin when compared with the control group. Patients with burns also failed to demonstrate the normal circadian variation in these peptides.
Adult↗
Effect of cadmium and bombesin on exocrine pancreatic secretions and plasma levels of gastrin and cholecystokinin (CCK) in rats.
The effects of cadmium and bombesin on exocrine pancreatic secretions and plasma levels of gastrin and cholecystokinin (CCK) were studied in anesthetized rats with pancreatic and gastric fistulas. Rats treated only with saline were used as controls. Both control and cadmium (0.1 mg per kg) treated rats were infused with saline, secretin, and bombesin (BBS). Blood and pancreatic juice samples were collected at regular time intervals. Plasma levels of gastrin and CCK were measured in blood samples by specific radioimmunoassay. Pancreatic juice samples were measured for volume, protein, and trypsin outputs. Compared to saline treated rats, outputs of volume, protein, and trypsin were significantly greater in cadmium treated rats. Plasma levels of gastrin were suppressed with secretin but significantly elevated with BBS. Plasma CCK levels were not different from basal after secretin or BBS in rats treated with either cadmium or saline. The results suggest that the administration of cadmium stimulated exocrine pancreatic secretion by a mechanism that does not involve gastrin or CCK. Bombesin may have a direct influence on the stimulation of exocrine pancreatic secretion in rats.
Animals↗
Metabolism of cholecystokinin-33 in vivo: effect of L-364,718, a CCK receptor antagonist.
Metabolism of cholecystokinin (CCK) and the effect of L-364,718, a specific CCK-A receptor antagonist, on the metabolism of CCK were examined in dogs. In conscious dogs, 45 min intravenous infusion of synthetic human CCK-33 (100 pmol/Kg/hr) caused an integrated CCK response over 90 min of 675 +/- 51 pmol-90 min/L, and the plasma CCK levels declined promptly with a t1/2 of 2.2 +/- 0.3 min after cessation. Organ extraction of CCK-33 by the kidney, mesenteric organs, and liver was examined in anesthetized dogs. From the gradients of the plasma levels between afferent and efferent vessels for each organ after bolus injection of CCK-33 (50 pmol/Kg), renal extraction ratio was 0.30 +/- 0.04, and mesenteric extraction ratio was 0.19 +/- 0.04. Hepatic extraction was not detected. T1/2 and extraction ratios were not affected by the preinjection of L-364,718 (20 nmol/Kg). The results indicate in dogs that exogenously administered CCK-33 is degraded by the mesenteric organs as well as the kidney but not by the liver, and that receptor-mediated mechanisms are not involved in these degradation pathways of CCK.
Anesthesia↗