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Biomedical subjects

U Keller

Publications and source records attributed to U Keller.

At least 343 records · Page 19Linked to original sources
PubMed1975

The physical properties of polyglycolic acid sutures (Dexon) in sterile and infected urine.

In a series of in vitro tests the time-dependent alteration of the resistance to breaking and of the extensibility of catgut and of polyglycolic acid sutures (Dexon) was examined. The threads were incubated in sterile and infected urine up to 10 days at 36 C. In the sterile urine environment Dexon dissolved on the 6th day and in the infected urine on the 3rd day. Catgut did not dissolve at all in the sterile urine and in the infected urine it dissolved only on the 8th day. In view of these results the use of Dexon in the urine environment may cause some concern, especially in an infection exists.

Bacteriuria↗
PubMedDate not supplied

Femtosecond near-field scanning optical microscopy.

We have developed an instrument for optically measuring carrier dynamics in thin-film materials with approximately 150 nm lateral resolution, approximately 250 fs temporal resolution and high sensitivity. This is accomplished by combining an ultrafast pump-probe laser spectroscopic technique with a near-field scanning optical microscope. A diffraction-limited pump and near-field probe configuration is used, with a novel detection system that allows for either two-colour or degenerate pump and probe photon energies, permitting greater measurement flexibility than that reported in earlier published work. The capabilities of this instrument are proven through near-field degenerate pump-probe studies of carrier dynamics in GaAs/AIGaAs single quantum well samples locally patterned by focused ion beam (FIB) implantation. We find that lateral carrier diffusion across the nanometre-scale FIB pattern plays a significant role in the decay of the excited carriers within approximately 1 microm of the implanted stripes, an effect which could not have been resolved with a far-field system.

Journal Article↗
PubMedDate not supplied

Protein metabolism assessed by 1-13C leucine infusions in patients undergoing bone marrow transplantation.

Patients receiving cytoreductive therapy and bone marrow transplantation (BMT) are known to develop marked protein catabolism. To assess the contribution of whole body protein breakdown, amino acid oxidation and incorporation into proteins, plasma leucine kinetics (1-13C-leucine infusion technique) were determined in six patients five times within 14 days before and after cytoreductive therapy (Cyclophosphamide and total body irradiation) and marrow transplantation. Nitrogen balance became negative (-0.20 +/- 0.04 g/Kg/24 hr) after cyclophosphamide (p less than 0.01) and was -0.25 +/- 0.05 g/Kg/24 hr 7 days after BMT in spite of total parenteral nutrition. Plasma leucine concentration increased after BMT by 67% (p less than 0.0015). Leucine plasma appearance was 1.20 +/- 0.15 mumol/kg/min before treatment, it increased slightly and transiently after cyclophosphamide, and increased again from day 5 to day 7 after BMT (p less than 0.01), suggesting increased protein break-down. Leucine oxidation increased from 0.27 +/- 0.07 before therapy to 0.97 +/- 0.16 mumol/kg/min (p less than 0.02) after cyclophosphamide and BMT. Nonoxidative leucine disappearance rate decreased slightly from 0.92 +/- 0.08 to 0.75 +/- 0.16 mumol/kg/min after BMT (ns). Leucine metabolic clearance rate decreased from 11.8 +/- 1.65 before therapy to 6.9 +/- 0.70 ml/kg/min (p less than 0.02) after cytoreductive therapy. After BMT it increased again to 9.9 +/- 1.5 ml/kg/min (p less than 0.02). The results demonstrate that patients undergoing cytoreductive therapy and bone marrow transplantation develop negative nitrogen balance due to increased protein breakdown associated with increased leucine oxidation and increased metabolic clearance rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Human insulin induces a higher glucagon response to induced hypoglycemia in short normal children, compared to porcine insulin.

After transfer of diabetic patients from porcine to human insulin, many reports emerged supporting an increased hypoglycemia unawareness. Several studies were then undertaken in both diabetic and healthy adults to investigate counterregulatory hormone responses to both porcine and human insulin-induced hypoglycemia as a possible underlying cause for this different hypoglycemia awareness. Most studies demonstrated similar neuroendocrine responses to both insulin species in adults. However, no such studies have ever been performed in healthy children. We undertook a double-blinded study of counterregulatory hormone responses to both porcine and human insulin-induced hypoglycemia in 17 short normal children randomly assigned to two groups, one receiving human and the other porcine insulin. We found similar responses of growth hormone, cortisol, epinephrine, norepinephrine and dopamine to both porcine insulin- and human insulin- induced hypoglycemia. Interestingly, we observed a significantly higher glucagon secretion when hypoglycemia was induced by human insulin. In conclusion, human insulin induces a higher glucagon secretion in healthy children than porcine insulin. Evidently, this observation cannot be extrapolated to diabetic patients. This study, however, further underlines the importance of performing investigations in children, since results found in adults differ from those observed in children.

Adolescent↗
PubMedDate not supplied

Spontaneous hypoglycemia associated with autoimmunity specific to human insulin.

A 55-yr-old woman with a history of Graves' disease experienced attacks of postprandial hypoglycemia for 6 yr. An insulinoma could not be confirmed by repeated fasting tests and by surgical pancreas revision. Extracted pancreatic insulin was chemically normal. Fasting plasma total insulin (1.22 nM = 183 microU/ml) and proinsulin (0.48 nM) were elevated and greatly increased after oral glucose. Glucose-clamp studies revealed delayed insulin clearance. Plasma free-insulin levels were normal. Insulin-binding antibodies were detected by enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay with human insulin as ligand but not with pork or beef insulins. Analysis with a modified ELISA suggested a monotypic and monoclonal human insulin autoantibody, which showed a restriction to the lambda-light chain. T-lymphocytes (predominantly helper) demonstrated increased responsiveness to beef, pork, and human insulins by proliferation assay. A T-lymphocyte line showed exclusively human insulin specificity. All this indicated cellular and humoral anti-human insulin autoimmunities. Clinically, the cause of hypoglycemia associated with elevated total insulin and proinsulin was misdiagnosed as atypical insulinoma. The study of total and free plasma insulin levels and sensitive antibody assays specific to human insulin were necessary to correctly diagnose autoimmune hypoglycemia.

Autoimmune Diseases↗
PubMedDate not supplied

Reduced postprandial hyperglycemia after subcutaneous injection of a somatostatin-analogue (SMS 201-995) in insulin-dependent diabetes mellitus.

The effect of a new octapeptide analogue of somatostatin (SMS 201-995) on blood glucose and gut hormone levels was studied in 10 C-peptide-negative, insulin-dependent diabetic (IDDM) subjects. On separate days, either 50 or 100 micrograms SMS or placebo was s.c. injected simultaneously with an identical insulin dose 30 min before a mixed meal. Postprandial blood glucose decreased after 100 micrograms SMS s.c. within 30 min from 8.9 +/- 0.7 to 7.8 +/- 0.6 mmol/L (P less than 0.001) and remained at similar levels during 180 min. In contrast, postprandial blood glucose concentration increased after placebo from 9.9 +/- 0.8 to 13.8 +/- 0.9 mmol/L (SMS versus placebo P less than 0.001). Plasma glucagon decreased rapidly after SMS to the limit of detection (P less than 0.001) and remained lowered during 180 min; in contrast, glucagon levels increased after the meal during the placebo study (SMS versus placebo P less than 0.001). Plasma growth hormone concentrations were significantly lower after SMS than after placebo (P less than 0.05). SMS abolished completely the postprandial increase in plasma gastrin and pancreatic polypeptide (PP) concentrations. Plasma free fatty acid (FFA) and triglyceride concentrations decreased after SMS, reaching significantly lower levels than after placebo (P less than 0.05 and P less than 0.01), respectively). Plasma SMS concentration increased rapidly after s.c. administration of SMS; its appearance preceded that of plasma free insulin after s.c. insulin injection. Fifty micrograms SMS was similarly effective as 100 micrograms in decreasing blood glucose, triglycerides, glucagon, and gut hormone concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Improved blood pressure control by monitoring compliance with antihypertensive therapy.

Compliance with antihypertensive therapy was monitored for three months using an electronic medication dispenser in 35 patients remaining hypertensive despite the once-daily administration of a blood pressure lowering drug (either as monotherapy or as fixed-dose combination therapy). During the monitoring of compliance, the treatment was unchanged but blood pressure decreased significantly (p < 0.001) from 167.9/100.4 +/- 16.3/7.2 mmHg (mean +/- SD) to 152.5/90.9 +/- 20.9/11.5 mmHg. The percentage of days with one opening per day was 80.8 +/- 20.5. Thus, discussing with the patient about compliance with the prescribed drug regimen and monitoring compliance for a few months allows better control of blood pressure. This most likely reflects increased compliance with antihypertensive drug therapy.

Adult↗
PubMedDate not supplied

Differential expression of the drug resistance markers DNA topoisomerase II alpha and glutathione S-transferase-pi in the histological compartments of Wilms' tumors.

More than 80% of the patients presenting with Wilms' tumor can be cured today. Some patients, however, fail to respond to chemotherapy. The objective of this study was to analyze the immunohistochemical distribution of two markers of cytostatic drug resistance, e.g. DNA topoisomerase II alpha (Topo II alpha) and glutathione S-transferase-pi (GST-pi) in 23 Wilms' tumor patients who had undergone an operation between 1984 and 1997. Eight patients had stage I disease, seven stage II, three stage III, four stage IV, and one stage V disease. Five tumors showed high malignancy histology. Investigations were carried out on formalin-fixed and paraffin-embedded tissue sections using the indirect immunoperoxidase method. Topo II alpha was predominantly present in the epithelial components of the specimens. It was more frequently found in anaplastic tumors. There was no difference in the presence of Topo II alpha in the epithelial components between specimens derived from treated and untreated patients. Topo II alpha was, however, less expressed in the blastemal and stromal elements of specimens after preoperative treatment. If GST-pi was present, it was confined to the epithelial components except for one case. While no expression of GST-pi was found in preoperatively untreated Wilms' tumors, it was present in epithelial compartments in 57% of tumors after chemotherapy. In conclusion, preoperative chemotherapy led to compartment-specific alterations in the expression levels of both markers indicating a contribution to treatment response of Wilms' tumors.

Antigens, Neoplasm↗