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Biomedical subjects

C Hahn

Publications and source records attributed to C Hahn.

At least 19 recordsLinked to original sources
PubMed1990

[Contrast-enhanced CT of the mediastinum in lymph node diagnosis].

In mediastinal lymphoadenopathy diagnostic problems arise if lymphomas are of the same density as cardial or vascular structures. For this reason, CT based on contrast enhancement must definitely ensure a significantly greater enhancement of vascular structures than of non-vascular ones during the entire scan period. We studied 4 groups of 20 patients each employing standardised CT examinations employing 100 ml. contrast medium in different concentrations (200 and 300 mg. iodine/ml., respectively) and an injection flow rate of 0.7 and 2.0 ml/s. The results show that higher iodine concentrations produce a significantly greater enhancement in the aorta than a lower iodine concentration independent of the flow rate. Although a lower flow rate slightly delayed the enhancement increase, this was nevertheless higher than 60 HU within a period of 4 minutes. Hence, we recommend to perform contrast enhanced CT of the mediastinum using lower flow rates (0.5-1.0 ml/s.) and a higher contrast medium concentration (300 mg. iodine/ml.).

Adult↗
PubMed1989

SWAT team approach to ventricular assistance.

In 1986, the Cardiovascular Research Institute in Sion, Switzerland, created a flying bridge-to-cardiac transplantation team. This team, consisting of two physicians, a physicist, a biomedical engineer, and two intensive care nurses, has participated in 23 bridges to cardiac transplantation in 11 cardiovascular surgery centers in Europe. The cardiac function of all patients was 100% supported by paracorporeal pneumatic biventricular Pierce-Donachy devices. Twenty of the 23 patients have had transplantation, and 11 are alive and well. The bridge-to-cardiac transplantation team, which travels with a transportable driver and the ventricle sets, supervises the bridged patients 24 hours a day until cardiac transplantation is performed.

Adolescent↗
PubMed1989

[Investigations on methods of quantitative polarization optical estimation of neutral carbohydrates in extracellular matrix].

By means of the fluorescence PAS-reaction using a Schiff-type reagent substituted with acriflavine, the neutral carbohydrates were demonstrable selectively in the human trophoblast basement membrane. The reaction product is characterized by a typical birefringence that can be measured in the polarized light. The results obtained from ascertainment of the dispersion of the birefringence before and after the histochemical reaction, as well, gave further evidence for specificity and a definite improvement of the measurement of path differences.

Acriflavine↗
PubMed1987

Partial nucleotide sequence of St. Louis encephalitis virus RNA: structural proteins, NS1, ns2a, and ns2b.

cDNA clones of the St. Louis encephalitis (SLE) virus genome have been obtained and the nucleotide sequence of 4.7 kb corresponding to the 5' terminal half of the genome determined. The genome contains a 5' noncoding region of 98 nucleotides followed by a single continuous open reading frame that encodes three structural proteins in the order capsid (C), membrane precursor (prM)-membrane (M), and envelope (E). Immediately following the C-terminus of E are located nonstructural proteins NS1 through NS3. The SLE amino acid sequence homology with yellow fever (YF), Murray Valley encephalitis (MVE), West Nile (WN), and dengue-2 (DEN) viruses over the sequenced region is 39, 66, 64, and 43%, respectively. The start of each SLE protein has been assigned on the basis of N-terminal sequence data and potential proteolytic cleavage sites homologous with YF and MVE viruses. Flaviviruses have conserved glycosylation sites in prM and NS1 proteins, although only one of the two glycosylation sites in the SLE E protein is conserved in MVE and DEN viruses. An evolutionary tree showing relationships of SLE, MVE, WN, YF, and DEN-2 flaviviruses is proposed on the basis of the amino acid sequences of the C proteins.

Base Sequence↗
PubMed1986

Glucose-insulin interactions during cardiopulmonary bypass. Hypothermia versus normothermia.

Since hypothermia is commonly used to lower local and general metabolism during cardiopulmonary bypass, we attempted to identify its specific effects on glucose-insulin interactions. A group of nondiabetic patients undergoing hypothermic (28 degrees C) cardiopulmonary bypass with ischemic (cold) cardiac arrest was compared to a similar group operated on under normothermic conditions with potassium cardioplegia. In the absence of exogenous dextrose administration, hypothermia blocked insulin secretion for the duration of the operation. It also inhibited insulin secretion in response to an exogenous dextrose load (e.g., the priming fluid of the cardiopulmonary bypass circuit) or a glucagon injection, but this inhibition was lifted by rewarming. Blood glucose levels, which during normothermia were mildly elevated even in the absence of dextrose administration, remained normal during the hypothermic phase of cardiopulmonary bypass. By the end of the rewarming period, however, blood glucose levels had reached the same level as observed under normothermic bypass, a fact suggesting that the cold inhibition of hepatic glucose production had been only temporary. Cold inhibition of hepatic glucose production also explains why glucose clearance after a sudden dextrose load was initially faster at low body temperature than at normal temperature. Glucose-clamp studies indicated that insulin resistance was initiated by anesthesia and surgical trauma, and further accentuated by cardiopulmonary bypass, in association with elevated levels of hormones indicative of surgical stress. Regardless of body temperature changes, the assimilation of glucose by nondiabetic subjects during and immediately after bypass called for the infusion of large doses of insulin. A comparison with diabetic subjects showed that insulin-dependent patients (type I diabetes) required no more insulin during cardiopulmonary bypass than normal subjects, whereas patients with type II diabetes exhibited a marked insulin resistance during the operation and in the immediate postoperative period.

Adult↗
PubMed1985

Interaction of the staphylococcin-like peptide Pep 5 with cell walls and isolated cell wall components of Gram-positive bacteria.

Unlike bacteriocins of Gram-negative bacteria, the strongly basic staphylococcin-like peptide Pep 5 lacked specific receptor mediated binding to sensitive Gram-positive bacteria. Studies with whole cells, purified cell walls, teichoic acids, and lipoteichoic acids strongly suggested that it binds reversibly via electrostatic interaction to negatively charged groups. Thus, Pep 5 binding could be reversed by sufficiently high concentrations of monovalent (K+, 150-250 mM) and divalent (Ca2+, 15-30 mM) cations (Fig. 1, 2) and by low pH (pH 2), where Pep 5 binding groups are protonated. Cells of Staphylococcus cohnii 22 with a reduced teichoic acid content showed a reduced Pep 5 binding capacity (Fig. 3). The results indicate that teichoic, teichuronic, and lipoteichoic acids are the unspecific cell wall binding sites for Pep 5.

Adsorption↗
PubMed1985

Cerulein-induced pancreatitis in rats: increased lysosomal enzyme activity and autophagocytosis.

The involvement of lysosomes in the normal secretory process of the exocrine pancreas and in the onset of acute, hormone-induced pancreatitis was studied. The enzymatic activities of cathepsin B and beta-galactosidase were determined in the pancreas of rats that had been stimulated by either maximal (0.25 microgram X kg-1 h-1) or supramaximal (5 micrograms X kg-1 h-1) concentrations of cerulein. Maximal stimulation led to a moderate increase in cathepsin B activity and the ultrastructural appearance of multivesicular bodies. Supramaximal stimulation resulted in formation of large cytoplasmic vacuoles and progressive destruction of acinar cells which was paralleled by a marked increase of lysosomal enzyme activity.

Amylases↗
PubMed1985

Sulfonylureas in insulin-dependent (type I) diabetes: evidence for an extrapancreatic effect in vivo.

The effect of glibenclamide treatment on insulin-mediated glucose disposal was studied in eight C-peptide-negative type I diabetic patients. The patients were studied twice by the euglycemic insulin clamp technique. One of the two experiments was preceded by glibenclamide treatment at the dose of 5 mg, three times daily for 15 days; half of the patients had the first test before and the second test after sulfonylurea treatment, and vice versa. Insulin was infused for four periods of 2 h each sequentially at 0.5, 1.0, 2.0, and 5.0 mU kg-1 min-1; for each insulin infusion period, the steady state plasma free insulin levels were comparable with or without glibenclamide. The mean +/- SEM plasma glucose concentration was 88 +/- 2 mg/dl in both experiments. The insulin-mediated glucose disposal rate was greater with glibenclamide during the first insulin infusion period (which generated plasma free insulin levels within the physiological range) 2.68 +/- 0.32 mg kg-1 min-1 with glibenclamide vs. 1.97 +/- 0.20 mg kg-1 min-1 without glibenclamide (P less than 0.005). However, glucose disposal rates did not differ in the diabetic patients with or without glibenclamide treatment during the second, third, and fourth insulin infusion periods, which generated plasma free insulin levels in the supraphysiological range. These results provide evidence for an extrapancreatic effect of glibenclamide at low insulin concentrations during euglycemic clamping in patients with insulin-dependent diabetes mellitus. However, this effect was not reflected clinically in either an increased rate of hypoglycemic reactions or decreased insulin needs during the short term period of treatment.

Adult↗
PubMed1985

Alterations of insulin and glucose metabolism during cardiopulmonary bypass under normothermia.

Anesthesia, surgical trauma, heparinization, priming volume composition, and temperature control of the heart-lung machine individually affect carbohydrate, protein, or lipid metabolism during cardiac operations. The impact of some of these factors on glucose and insulin regulation was assessed before, during, and after normothermic cardiopulmonary bypass in nondiabetic patients with use of a servo-controlled insulin delivery system. With a glucose-free prime, cardiopulmonary bypass induced a slight hyperglycemia but no endogenous insulin response, suggesting a partial inhibition of insulin secretion. Nonetheless, insulin release could be stimulated by exogenous glucagon. A glucose load in the priming fluid led to marked and persistent hyperglycemia without commensurate insulin release. Elevated stress hormone levels, a concomitant reduction of insulin release and insulin action, and a depression of peripheral glucose utilization, as demonstrated by glucose clamp experiments, contributed to these perturbations of glucose and insulin metabolism. Although the metabolic alterations observed are not critical in routine cardiac operations, they may become clinically significant in postoperative states with unusual persistence of stress conditions.

Blood Glucose↗
PubMed1979

[Tetralogy of Fallot: results of 77 hemodynamic controls after complete correction].

77 patients (representing 91% of all survivors) underwent catheterization within 5 months of surgical repair of tetralogy of Fallot. The data show that residual pulmonary gradient is significantly higher in patients with infundibular and valvular stenoses than in patients with infundibular stenoses only, whereas the method of intracardiac repair (patch) had no influence on residual gradient. Significant pulmonary insufficiency was found almost exclusively when a patch was extended through the pulmonary annulus. Hemodynamic results were excellent in 37% of cases, good in 51%, satisfactory in 3% and unsatisfactory in 9%. Finally, primary intracardiac repair in children below 4 years of age yielded excellent or good results in all cases: this suggests that toal correction should be performed without previous aorto-pulmonary anastomoses in this youngest group of patients.

Cardiopulmonary Bypass↗