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Biomedical subjects

D Jung

Publications and source records attributed to D Jung.

At least 145 records · Page 8Linked to original sources
PubMed1984

An improved micro-scale liquid-chromatographic assay for piperacillin in plasma and urine.

An accurate, sensitive, and specific liquid-chromatographic method is described for measuring piperacillin in plasma and urine. Plasma samples deproteinized with two volumes of acetonitrile containing 1.2 mg of the internal standard, p-nitrobenzene sulfonamide, per liter are centrifuged. The clear supernate is evaporated under nitrogen, and the residue is reconstituted in 50 microL of the mobile phase (32/68 by vol acetonitrile/water, adjusted to pH 2.5 with 85% phosphoric acid), of which 10 microL is injected onto a reversed-phase (C-18) column. Urine samples are diluted 10-fold with distilled water, an equal volume of acetonitrile containing 3 mg of the internal standard per liter is added, and 20 microL is chromatographed. Stability studies indicate that storage conditions are critical for both plasma and urine. Piperacillin in plasma is stable at -70 degrees C for at least six weeks, but 100% of it is degraded during the same time at -20 degrees C. Piperacillin in urine is also stable at -70 degrees C for six weeks, but 20% is degraded during six weeks at -20 degrees C.

Chromatography, Liquid↗
PubMed1983

Changes of alanine-sodium co-transport during maturation of Xenopus laevis oocytes.

Maturation of full grown Xenopus oocytes is associated with a decrease of their capacity to transport amino acids and nucleosides. Nevertheless, the transport continues at a reduced rate until the time of metaphase arrest when the oocytes are ready for shedding. We have found that the L-alanine transport in unfertilized, shed oocytes is a saturable process which is Na+-dependent. The stoichiometrical ratio between sodium and alanine is 2:1. Comparison with the alanine uptake in full grown oocytes shows that during maturation Vmax is strongly reduced while Km and the stoichiometrical ratio of sodium and alanine is unaffected. Lowering the osmolarity of the shedding medium reduces the rate of uptake of alanine below the rates seen after shedding into isotonic media. The transport rates amongst the individual oocytes differ. They do not fit to a Gaussian distribution. In addition, in individual oocytes, there exists no correlation between the variations of the transport rates for amino acids and nucleosides, which are also taken up by the unfertilized, shed oocytes.

Alanine↗
PubMed1983

[Internal intestinal splinting with a soluble tube for the prevention of recurrent adhesion ileus].

An absorbable, non-toxic, easy gliding, cross-linked gelatine tube has been developed to prevent and to treat chronical adhesion ileus. The tube is patterned upon the interior intestinal splinting with long tubes. By doing a small enterotomy it was possible to splint the whole intestine in pigs or endangered parts within a few minutes. The flexible gelatine tube does not kink and is melting off from the surface. It prevents the intestine from kinking and does not cause any lesions even on previously damaged intestinal walls. Possible complications seen by insertion and extraction of conventional tubes were not observed.

Animals↗
PubMed1982

Structural dissimilarities in different regions of the pineal gland of Pirbright white guinea-pigs.

In the present study, the proximal, intermediate and distal parts of dumbbell-shaped pineal glands of Pirbright White guinea-pigs were investigated with respect to structural dissimilarities. The most conspicuous difference was that while in the proximal part the pinealocytes were arranged in a random fashion, the intermediate and distal regions, except a small ventral area in the latter, exhibited a prominent follicular arrangement of the pinealocytes. Concretions were restricted to the subcapsular region of the intermediate part, whereas cells with hyperchromatic nuclei increased in number in an anterior-posterior direction. In males, pinealocyte nuclear size did not differ significantly in the regions investigated, whereas in females the karyometric results were much more heterogeneous. Exposure of male guinea-pigs to continuous illumination for 45 days resulted in (i) a 25% decrease of pineal volume, the intermediate area being relatively little affected, (ii) an increase in the number of follicles and (iii) a decrease in pinealocyte nuclear size, especially in a ventral zone of the proximal part of the pineal gland.

Animals↗
PubMed1982

Thiopental disposition as a function of age in female patients undergoing surgery.

The effect of age on the disposition kinetics of thiopental was studied in 22 lean female patients having a body mass index (weight (kg/height(m)2) less than 30 and whose age ranged between 25 to 83 years. Patients underwent primarily abdominal surgery. A strong positive correlation between age and the apparent volumes of distribution, V beta and Vss, was found (P less than 0.001). No significant relationship was found between total body clearance and age. The elimination half-life (t1/2) of thiopental increased with age, and was primarily a function of volume of distribution. The free or unbound fraction of thiopental in serum (alpha) ranged between 0.168 and 0.276 and was significantly correlated with age (P less than 0.005). Multiple regression analysis indicated that age was the independent variable which contributed most the variability in t1/2, V beta, and Vss. No conclusion can be reached concerning the potential differences in anesthetic induction doses required as a function of age; however, these data suggest that care may be required in the use of a balanced anesthetic technique in the elderly as a result of prolonged elimination.

Abdomen↗
PubMed1982

Thiopental disposition in lean and obese patients undergoing surgery.

The effect of obesity on the disposition kinetics of thiopental was studied in seven morbidly obese (age 25 to 46 years) and eight age-matched lean patients (age 25 to 43 years), undergoing primarily abdominal surgery. Based upon total (bound + free) thiopental concentrations, the average (+/-SD) volumes of distribution in the terminal disposition phase and at steady-state (V beta and V ss) were significantly larger in the obese (7.94 +/- 4.55 1/kg and 4.72 +/- 2.73 1/kg, respectively) than in the age-matched lean patients (1.95 +/- 0.63 1/kg and 1.40 +/- 0.46 1/kg, respectively). Clearance of total thiopental, normalized for total body weight was not significantly different between the obese (0.18 +/- 0.081 . h-1 . kg-1) and lean patients (0.21 +/- 0.06 1 . h-1 . kg-1). However, total body clearance not normalized for total body weight was significantly larger in the obese (24.98+/- 14.87 1/h) than in the lean patients (11.86 +/- 3.66 1/h). The elimination half-life of thiopental was significantly longer in the obese (27.85 h) than in the lean patients (6.33 h) and this difference was primarily a function of a larger apparent volume of distribution for thiopental. The unbound fraction of thiopental in serum (range, 17.8 per cent to 27.6 per cent) was not correlated with the degree of obesity. The most appropriate means of comparing intrinsic metabolizing capacity (i.e., normalized vs. non-normalized for weight) between lean and obese subjects remains unresolved.

Abdomen↗
PubMed1982

[Carcinoid tumors of the gastro-intestinal-tract (author's transl)].

The prognosis of carcinoid tumors of the Gastro-Intestinal Tract (GIT) is determined by the site and size of the tumors. Carcinoid of the vermiform appendix and the rectum cause early symptoms making early diagnosis and treatment relatively easy. The 5-year-survival rate is 99% and 83% respectively. Carcinoid tumors involving the stomach and the colon with 5-year-survival rates of 52% and 53% respectively have an unfavourable prognosis. In between is the carcinoid tumor of the small intestine with a survival rate of 60%. Tumors with diameter less than 2 cm can be excised locally. Bigger tumors--as a rule--must be managed according to the principles of tumor surgery. The operative treatment of metastasis improves the prognosis especially of small intestine carcinoids. One should endeavor to remove also metastasis of carcinoid tumors of other localizations.

Apudoma↗
PubMed1981

Molecular symmetry and metastable states of enzymes exhibiting half-of-the-sites reactivity.

Half-of-the-sites reactivity in oligomeric enzymes has generally been accepted as evidence for structural asymmetry between subunits. However, we show that the symmetric two-state allosteric model [Monod, J., Wyman, J., & Changeux, J.-P. (1965) J. Mol. Biol. 12, 88-118] is quantitatively consistent with half-of-the-sites reactivity data for several hexameric and tetrameric enzymes. Specifically, the time courses for both the modification and the inactivation of glutamate dehydrogenase by glutamyl alpha-chloromethyl ketone and uridine diphosphoglucose dehydrogenase by 5-(iodoacetamidoethyl)aminonaphthalene-1-sulfonic acid are fit with just five parameters for each enzyme-modifier pair. In the case of glyceraldehyde-3-phosphate dehydrogenase, the time courses for modification of the yeast enzyme by iodoacetic acid and the rabbit-muscle enzyme by 3,3,3-trifluorobromoacetone are fit with the same model, and parameter values from these fits are used to generate theoretical inactivation curves which are found to agree well with the experimentally measured inactivation. We conclude that half-of-the-sites reactivity, if it is not an artifact of residual heterogeneity, could be a kinetic phenomenon related to metastability of partially modified states of a symmetric oligomer and that asymmetry between subunits should therefore not necessarily be inferred from such behavior. If similar metastability occurs in substrate binding, it may play a significant role in mechanism of catalysis and control. In such cases, the virtual inaccessibility of the substrate binding equilibrium would preclude conventional quasi-equilibrium models for the enzyme kinetics.

Animals↗
PubMed1981

CBF--computer handling of chemical and biological facts.

CBF is an EDP-supported documentation and retrieval system for structural formulas of defined organic compounds and their biological activities. It fits the needs of a firm concerned with drug research for prevailing unpublished internal data, which the scientists can use for reflections on structure-activity relationships and to search for lead compounds with specific activity profiles.

Biology↗