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Biomedical subjects

R A Frost

Publications and source records attributed to R A Frost.

At least 55 records · Page 3Linked to original sources
PubMed1995

Insulin-like growth factor binding protein-3 proteolysis in children with insulin-dependent diabetes mellitus: a possible role for insulin in the regulation of IGFBP-3 protease activity.

Limited proteolysis of serum insulin-like growth factor (IGF) binding protein (IGFBP)-3 has been described in various conditions and may increase the bioavailability of IGFs. The physiological regulators of serum IGFBP-3 protease activity are unknown. To characterize the relationship between insulin and IGFBP-3 protease activity, we have examined serum IGFBP-3 proteolysis in children with untreated insulin-dependent diabetes mellitus (IDDM) and have followed the effect of insulin therapy on serum IGFBP-3 proteolysis at 1 day, 1 week, and 1 month after the initiation of insulin therapy. Ligand blot analysis of sera from untreated children with IDDM showed that intact IGFBP-3 was 50 +/- 9% of the age-matched control pool. After the initiation of insulin treatment, IGFBP-3 did not change significantly at 1 day after treatment but increased dramatically at 1 week (90 +/- 13%) and 1 month after treatment (102 +/- 13%). In contrast, when measured by immunoradiometric assay (which detects both intact and fragments of IGFBP-3), IGFBP-3 levels were 70% of the control pool before insulin therapy and did not increase significantly until 1 month after treatment. Immunoblot analysis demonstrated that intact IGFBP-3 doublet was diminished to 41 +/- 7% of controls, whereas the major IGFBP-3 fragment (30 kDa) was increased in IDDM sera before insulin therapy. After insulin, intact IGFBP-3 increased and the 30-kDa fragment decreased to values comparable to those observed in controls. In vivo IGFBP-3 proteolysis, which implies preassay exposure of serum IGFBP-3 to proteases, was estimated by immunoblot analysis. IGFBP-3 proteolysis was increased before insulin therapy (160 +/- 9%) and decreased to 81 +/- 9% at 1 week and to 71 +/- 11% at 1 month after insulin treatment. Residual serum IGFBP-3 protease activity was estimated by a 125I-IGFBP-3 degradation assay. Serum IGFBP-3 protease activity increased significantly in untreated diabetics, compared with activity in controls (128 +/- 5% vs. 99 +/- 11%). During insulin therapy, serum IGFBP-3 protease activity decreased gradually to 91 +/- 5% of control values at 1 month. Molecular sizes of the IGFBP-3 proteolytic fragments (30 kDa, 24 kDa, and 19 kDa) and inhibition profile of IGFBP-3 protease were similar in IDDM and pregnancy sera, indicating that similar proteases (cation-dependent serine proteases) were active in both conditions. These results suggest an important role of insulin in the regulation of IGFBP-3 protease activity. Increased IGFBP-3 proteolysis in the sera of children with IDDM may serve to counteract the catabolic state induced by insulin deficiency.

Adolescent↗
PubMed1994

Phosphorylation of 17 beta-hydroxysteroid dehydrogenase in BeWo choriocarcinoma cells.

OBJECTIVE: The purpose of this study was to test whether 17 beta-hydroxysteroid dehydrogenase might exist in a phosphorylated form. STUDY DESIGN: Phosphorylation of 17 beta-hydroxysteroid dehydrogenase was evaluated in BeWo choriocarcinoma cells. The phosphorylation of 17 beta-hydroxysteroid dehydrogenase expressed in Escherichia coli as a glutathione transferase fusion protein was also studied. RESULTS: Human BeWo choriocarcinoma cells were metabolically labeled with phosphorus 32 orthophosphate. Immunoprecipitates were prepared with rabbit anti-17 beta-hydroxysteroid dehydrogenase antiserum from the labeled cells and separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A phosphorylated protein with a molecular size of 35 kd was obtained from anti-17 beta-hydroxysteroid dehydrogenase immunoprecipitates, which suggested that 17 beta-hydroxysteroid dehydrogenase was phosphorylated in BeWo cells. The predominant phosphoamino acid was phosphoserine. 17 beta-Hydroxysteroid dehydrogenase expressed in E. coli as a glutathione transferase fusion protein was a substrate of protein kinase A in vitro. Protein kinase A phosphorylated the recombinant 17 beta-hydroxysteroid dehydrogenase exclusively on serine. Incubation of BeWo cell lysates with bacterial alkaline phosphatase led to a decrease in the oxidative activity of 17 beta-hydroxysteroid dehydrogenase. Incubation of the alkaline phosphatase inhibitor levamisole with BeWo cell lysates resulted in a higher estradiol-to-estrone conversion rate, compared with cell lysates without any treatment. CONCLUSION: Our data suggest that 17 beta-hydroxysteroid dehydrogenase may exist in phosphorylated forms and that phosphorylation may regulate the activity of 17 beta-hydroxysteroid dehydrogenase in vivo.

17-Hydroxysteroid Dehydrogenases↗
PubMed1994

Phosphorylation of insulin-like growth factor binding protein-1 in patients with insulin-dependent diabetes mellitus and severe trauma.

We have determined the level of phosphorylated insulin-like growth factor binding protein-1 (pIGFBP-1) in serum during two catabolic states: diabetes mellitus and trauma. Human sera were incubated with [125I]IGF-I for 2 h followed by non-denaturing PAGE. [125I]IGF-I/IGFBP-1 complexes from serum co-migrated with a pure p4IGFBP-1 standard. Complex formation was specifically inhibited by unlabeled IGF-I. The migration of IGF-I/pIGFBP-1 complexes was retarded by IGFBP-1 antibodies, but not by antibodies against IGFBP-2 or IGFBP-3. Sera from three severely traumatized patients had up to 12-fold more pIGFBP-1 than sera from age-matched controls. The level of pIGFBP-1 was reduced in all three patients upon hospital discharge. Sera from three patients with insulin dependent diabetes mellitus (IDDM) and severe ketoacidosis (DKA) had more pIGFBP-1 than controls. Administration of insulin to DKA patients lowered the level of pIGFBP-1. The present study shows that IGFBP-1 exists as a free, high affinity, phosphorylated form in vivo during two catabolic states.

Accidents, Traffic↗
PubMed1993

Insulin-like growth factor binding protein-1 inhibits the mitogenic effect of insulin-like growth factors and progestins in human endometrial stromal cells.

This study describes the effects of insulin-like growth factors (IGFs), progestins, and IGF binding protein-1 (IGF-BP1) on DNA synthesis in human endometrial stromal cells. Endometrial stromal cells treated with IGF-I or IGF-II or progestins increased their rate of DNA synthesis 3-6-fold. In a time study, IGF-I or IGF-II stimulated DNA synthesis 3-fold in 24 h. An equivalent increase by medroxyprogesterone acetate (MPA) required 48 h. Progestin-stimulated DNA synthesis was inhibited completely by an equimolar concentration of the antiprogesterone RU486. IGF-I-stimulated DNA synthesis was inhibited completely by IGF-BP1. Half-maximal inhibition of IGF-I-stimulated DNA synthesis occurred when IGF-I and IGF-BP1 were at equimolar concentrations. Non-phosphorylated and phosphorylated forms of IGF-BP1 were equipotent inhibitors of IGF-I-stimulated DNA synthesis. IGF-BP1 also inhibited progestin-stimulated DNA synthesis. Half-maximal inhibition of progestin-stimulated DNA synthesis occurred at 100 ng/ml of phosphorylated IGF-BP1. Phosphorylated IGF-BP1 was a 3-4-fold more potent inhibitor of progestin-stimulated DNA synthesis than the nonphosphorylated form. The inhibition by IGF-BP1 of progestin-stimulated DNA synthesis was reversed by an equimolar concentration of IGF-II. This study suggests that progestins regulate an autocrine growth control loop in the endometrium that involves IGFs, IGF receptors, and IGF-BPs.

Adult↗
PubMed1992

Postaxial polydactyly. A case report.

Polydactyly is a fairly common congenital foot deformity. Treatment may include simple shoe modification or surgical intervention. Careful preoperative planning must be undertaken with each patient because of the uniqueness of each individual case. A case of type A postaxial polydactyly was presented with a brief review of classification, etiology, and treatment.

Adult↗
PubMed1992

Percutaneous endoscopic gastrostomy in 41 patients: indications and clinical outcome.

Percutaneous endoscopic gastrostomy, under local anaesthetic, was successfully used in 40 out of 41 patients referred for nutritional support. The indications were neurological disorders of swallowing in 32 patients, head and neck cancer in four patients and supplemental feeding in a miscellaneous group of five patients. The main complications of this procedure were one failed insertion and one peritubal infection. At prospective follow-up, the tube continued to function in 16 patients (seven at home) a mean of 184 days post-insertion (range 6-610 days). In 11 patients resumption of swallowing at a mean of 122 (20-390) days allowed tube removal. Thirteen patients died from their disease, a mean of 96 (12-320) days post-insertion. Patient tolerance and patient and carer satisfaction have been excellent and early results suggest that recovery of speech and swallowing in acute neurological disorders may be enhanced. Percutaneous endoscopic gastrostomy should be performed in all patients referred for a gastrostomy and should be considered in all patients requiring long-term tube feeding.

Adult↗
PubMed1991

Insulin-like growth factor-binding protein-1 is phosphorylated by cultured human endometrial stromal cells and multiple protein kinases in vitro.

The insulin-like growth factor-binding protein IGF-BP1 is a major secretory protein of human endometrial stromal cells decidualized in culture. Anion exchange chromatography and nondenaturing gel electrophoresis showed IGF-BP1 to exist in five electrophoretically and chromatographically distinct isoforms. IGF-BP1 variants migrated as a quintet on nondenaturing polyacrylamide gels and as a single band (28 kDa) on sodium dodecyl sulfate-polyacrylamide gels. Alkaline phosphatase treatment reduced the IGF-BP1 variants to a single band. Cells incubated with [32P]orthophosphate for 12 h secreted four 32P-labeled IGF-BP1 phosphovariants, and their migration coincided with those bands that were eliminated by alkaline phosphatase treatment. In cells treated with medroxyprogesterone acetate and relaxin, the concentration of phosphorylated IGF-BP1 was increased dramatically as compared with controls. All the phosphovariants were confirmed to be IGF-BP1 by their ability to be supershifted on nondenaturing polyacrylamide gels after binding a monoclonal antibody to IGF-BP1. Thin layer electrophoresis of IGF-BP1 acid hydrolysates showed IGF-BP1 to be phosphorylated exclusively on serine. Non-phosphorylated IGF-BP1 was phosphorylated by the catalytic subunit of the cAMP-dependent protein kinase and casein kinase II in vitro. This suggests that IGF-BP1 may be a substrate of multiple protein kinases in vivo.

Adult↗
PubMed1988

Modified dual label Schilling test for pancreatic exocrine function.

The modified dual-label Schilling test, as further developed in kit form by Amersham International plc (UK), has been assessed in two separate centres. Since the outcome was similar in each centre, the results in 66 subjects were amalgamated. Using a cut-off point for the 58Co/57Co ratio of 0.52--as derived from studies in 10 healthy volunteers--to separate normal from abnormal results, the specificity of the test was 88%. However, the test's sensitivity in chronic pancreatic disease was only 50%: normal results occurred in 5 of 8 patients with pancreatic cancer (including 2 with steatorrhoea), and 9 of 21 with chronic pancreatitis (including 1 with steatorrhoea). The possible reasons for the test's poor sensitivity are discussed.

Adult↗
PubMed1988

Diagnosis and grading of chronic pancreatitis by morphological criteria derived by ultrasound and pancreatography.

The most commonly used modalities in the diagnosis of chronic pancreatitis are ultrasonography, computed tomography (CT) and endoscopic retrograde pancreatography (ERP). Computed tomography scanning is only of value in severe chronic pancreatitis. Both ultrasound and pancreatography are capable of showing ductal changes in mild forms of the disease, but comparison of the two methods has been difficult. A scheme of morphological criteria and descriptive terminology of pancreatitis was applied to 58 out of 85 patients with a firm clinical diagnosis of chronic pancreatitis. Twenty-seven patients were excluded from the study, four with a faulty clinical diagnosis and 23 with non-diagnostic pancreatograms. There was an exact classification into normal, equivocal, mild, moderate or marked chronic pancreatitis in 50 out of 58 patients (86%) and an almost perfect correlation (+ or - one grade) in 54 out of 58 (93%). There were four discrepancies. Ultrasound examination missed focal pancreatitis in the tail, a small cavity in the uncinate process and a variant of chronic pancreatitis. One ultrasound scan was of poor quality. Morphological grading by different techniques is feasible and use of this scheme can reduce diagnosis to a simple and specific set of rules.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1988

Prospective comparison of double contrast barium enema plus flexible sigmoidoscopy v colonoscopy in rectal bleeding: barium enema v colonoscopy in rectal bleeding.

Rectal bleeding often heralds serious colonic disease. The literature suggests that colonoscopy is superior to barium enema plus sigmoidoscopy, although no good comparative studies exist. Seventy one patients with overt rectal bleeding had prospectively flexible sigmoidoscopy, double contrast barium enema and colonoscopy completed independently. Against the gold standard, the sensitivity and specificity of colonoscopy were 0.69 and 0.78 respectively for a spectrum of colonic lesions, while for combined flexible sigmoidoscopy and double contrast barium enema these values were 0.80 and 0.56, respectively. When assessing adenoma or carcinoma, colonoscopy was more sensitive at 0.82 v 0.73, while flexible sigmoidoscopy plus double contrast barium enema was superior for detecting diverticular disease. The positive predictive value for colonoscopy was 0.87 against 0.81 for flexible sigmoidoscopy and double contrast barium enema. This study confirms that colonoscopy should be a first line investigation in subjects likely to require biopsy or therapeutic intervention.

Barium Sulfate↗
PubMed1987

Upper gastrointestinal endoscopic ultrasonography in gastroenterology.

Endoscopic ultrasound is a new technique in which high-frequency, high-resolution real-time ultrasound images are obtained from within the gastrointestinal tract by use of an ultrasound probe incorporated into the tip of a fibreoptic endoscope. Forty patients were scanned for gastrointestinal indications. In six patients the scans were technically unsuccessful, in three of these because of difficulties with the prototype instrument. New information was obtained in 20 patients, later confirmed by other means in 12. Endoscopic ultrasound did not provide any new information in 14 patients. The technique shows considerable promise in patients with pancreatic disorders and gut-wall malignancies. It has the ability to provide images with a spatial resolution unobtainable by other imaging methods.

Duodenal Diseases↗
PubMed1987

A comparison of Golytely and standard preparation for barium enema.

A randomized prospective trial was performed comparing Golytely (with bisacodyl) with our standard two-day catharsis and bowel washout regimen as colon preparation for double-contrast barium enema examinations. Of the 107 patients who participated, 50 received the standard preparation and 57 Golytely. Two radiologists reviewed the enema films without knowledge of which preparation had been used. No significant difference was detected either in the number of failed preparations or in the quality. We conclude that routine use of Golytely is preferable to methods involving catharsis and standard tap water enemas for barium enema examination, on the grounds that it is equally effective, yet more convenient for patients and for the radiology department, and reduces total costs.

Barium Sulfate↗
PubMed1986

Prenatal and immediate postnatal ultrasonographic diagnosis of ureterocele.

We report three patients in whom hydronephrosis was diagnosed by ultrasonography in utero. In two fetuses, ureteroceles were detected prenatally and these proved to be the cause of obstruction. In the third, bilateral simple ureteroceles were discovered immediately after birth. In the last patient, failure to see ureteroceles in utero may have been related to the phenomenon of ureterocele eversion and prolapse into the ureter. Ultrasonographers should be aware of this prolapse phenomenon as a potential pitfall for both the in utero and postpartum diagnosis of ureterocele.

Adult↗
PubMed1986

The combination of endoscopic sphincterotomy and percutaneous abscess drainage in the management of complicated biliary pancreatitis.

We report four patients with a protracted history of acute pancreatitis complicated by infected pseudocysts or abscesses. Ultrasonography showed that each patient had cholelithiasis. Endoscopic biliary sphincterotomy was performed resulting in the release of stones, gravel, or pus in all four cases. Three of the patients had successful percutaneous abscess drainage, and one patient was drained surgically. The abscesses all resolved, but one patient died suddenly of acute pulmonary embolism. The other three patients are well. We recommend this combined approach to pancreatic abscess drainage because, if there is obstruction to the flow of pancreatic juice at the ampulla of Vater, it is likely that the pancreatitis and abscess will fail to resolve.

Abscess↗
PubMed1986

The benefit of emergency nasobiliary drain in cholelithiasis with ascending cholangitis, coagulopathy, and thrombocytopenia.

Severe coagulopathy in a male patient with septicemia, renal failure, and obstructive jaundice secondary to cholelithiasis precluded safe endoscopic sphincterotomy. A temporary nasobiliary drain, inserted at endoscopic retrograde cholangiopancreatography, decompressed the biliary tree, allowing eventual safe sphincterotomy and bile duct clearance after correction of coagulopathy and improvement in his clinical condition.

Blood Coagulation Disorders↗
PubMed1985

Pain after barium enema: effect of CO2 and air on double-contrast study.

One hundred fifty-one consecutive patients scheduled for double-contrast barium enema studies were assigned randomly to insufflation with either air or carbon dioxide (CO2) in a double-blind, prospective trial. Within 24 hours after the enema study, the patients were contacted by telephone by an interviewer, who completed a standard questionnaire. Radiographs from the enema studies were assessed for quality by two radiologists. Pain experienced after the procedure was graded from 0 (none) to 4 (severe). Clinically relevant (grades 2-4) pain was experienced by 30% of patients after insufflation with room air, compared with 11% of patients in whom CO2 was used for insufflation (P = .005). The mean pain score for CO2 was 0.4, and for room air, 1.2 (P less than .005). Although five patients experienced grade 4 pain after insufflation with air, no patient reported severe pain after CO2 insufflation. Post-evacuation films confirmed there was significantly less residual gas in the CO2 group. The quality of radiographs was equal in the two groups. CO2 has advantages for use in the double-contrast barium enema examination.

Air↗