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Biomedical subjects

W Kessler

Publications and source records attributed to W Kessler.

At least 55 records · Page 3Linked to original sources
PubMed1990

Generation of volatile hydrocarbons from amino acids and proteins by an iron/ascorbate/GSH system.

Incubation of free, but not of peptide-bound methionine in an iron/ascorbate system resulted in ethylene generation, which was inhibited by glutathione. Leucine and isoleucine, however, when incubated in an iron/ascorbate/GSH system, released small amounts of propane and ethane, respectively. Peptide-bound leucine additionally yielded butane, as did bovine serum albumin or casein. Hydrocarbon generation from amino acids was inhibited by hydroxyl radical scavengers, but catalase and superoxide dismutase were more efficient. Additionally, ethane and propane generation in this system was optimal at pH 6.2 suggesting the involvement of protonated superoxide besides OH-radicals which attack the side chains of Leu and Ile and very probably produce carbon-centered radicals, which should abstract a hydrogen atom from the thiol group of GSH resulting in the formation of saturated hydrocarbons.

Amino Acids↗
PubMed1990

Dose-dependent emergence of preneoplastic foci in rat livers after exposure to 2-nitropropane.

Male and female Sprague-Dawley rats, 4-6 days old were exposed for 3 weeks (6 h/day, 5 days/week) to 2-nitropropane vapours of 0, 25, 40, 50, 80 and 125 ppm. One week later polychlorinated biphenyls (Clophen A50, 10 mg/kg body weight) were administered for promotion twice a week for 8 weeks. Thirteen weeks after starting the experiments the logarithms of the numbers of preneoplastic liver foci deficient in adenosine-5'-triphosphatase were found to be linearly related to the exposure concentrations of 2-nitropropane. Male rats exhibited an approximately four times lower foci incidence than females.

Adenosine Triphosphatases↗
PubMed1990

Spectrophotometric determination of pyrrole-like substances in urine of rat and man: an assay for the evaluation of 2,5-hexanedione formed from n-hexane.

Male Wistar rats exposed to atmospheric n-hexane excreted in their urine substances which gave rise to absorption spectra like those of pyrroles after the reaction with Ehrlich's reagent. A simple spectrophotometric assay was developed to determine these "pyrrole-like substances" in urine. Their excretion kinetics were evaluated by exposing rats for 8 h to atmospheric n-hexane concentrations between 50 and 3000 ppm. The dose-response curve revealed saturation kinetics according to Michaelis-Menten, Vmax being 1.12 [delta E526.ml urine/8 h n-hexane exposure] and "Km", the atmospheric n-hexane concentration at Vmax/2, being 250 ppm. The excretion of pyrrole-like substances closely correlated with that of 2,5-hexanedione measured by Fedtke and Bolt (1987). Pyrrole-like substances were also found in the urine of a male volunteer. When exposing the person for 3 h to atmospheric n-hexane at a concentration of 146 ppm (equivalent to 55 ppm/8 h) the excreted amount was twice the background value. Due to the sensitivity of this assay it is possible to determine pyrrole-like substances in urine according to the present German MAK or US TLV conditions for n-hexane (50 ppm/8 h).

Animals↗
PubMed1990

Use of a fully implantable drug delivery system in the treatment of acute leukemias and disseminated lymphomas.

In an open study, 42 venous Port-A-Cath systems (PAC) were implanted in 40 patients with AML (12), ALL/AUL (11), NHL with bone marrow infiltration (8), Hodgkin's lymphoma (3), solid tumors (5) and severe aplastic anemia (1). Mean duration of system use was 212 days. The cumulated duration of use of all systems was 8.883 days. 1,627 blood samples were taken from the PAC. Blood sampling was possible on 8,696 of 8,883 days of cumulated access (98%). A total of 522 blood transfusions were administrated. Fifty-two episodes of neutropenia (granulocyte counts less than 0.5 x 10(9)/l) with a mean duration of 17 days were observed in the group of the 23 patients with acute leukemias. A total of 25 complications were registered. The incidence was 2.8/1,000 days of access. Twelve complications were regarded as severe. Venous thrombosis was observed in 3 cases. In addition, there were 2 disruptions of the catheter, 1 disconnection, 1 looping and 4 local infections. The rate of systemic infection could not be accurately estimated because the catheter was always left in place and antibiotic treatment was started immediately in case of fever with or without bacteriemia. The overall rate of catheter-related complications in patients with acute leukemia was not higher than in patients with solid tumors.

Acute Disease↗
PubMed1989

[Serological and clinical studies of endemic treponematosis in the Republic of Mali].

In Mali, in the sahelian zone, the prevalence of non venereal endemic syphilis is currently equivalent to the prevalence that existed before the eradication campaigns of the years 1950-60. Because new control programmes of the disease had to be initiated, studies have been performed to measure the current impact of the mass campaigns with long acting penicillin, and to look for a simple method that could rapidly assess the impact of the control programmes. These studies underline that the control of endemic syphilis in these areas cannot rely solely upon the health care facilities, but that mobile strategies and mass campaigns will perhaps always be needed in the areas not covered by the health care facilities. The studies demonstrate also the interest of a technique such as the quantitative VDRL for the epidemiologic surveillance of endemic syphilis.

Adolescent↗
PubMed1987

Pharmacoarteriography in the evaluation of impotence.

Progress in diagnosis and therapy of impotence is handicapped by the absence of a validated and objective method for evaluating the vascular system; a gold-standard for vasculogenic impotence is needed. Prior experience has indicated that conventional arteriography in unanesthetized patients is unreliable in evaluation of the penile arterial supply. We have improved our arteriographic methods by the routine application of selective pudendal injections, vasodilation pharmacoangiography with nitroglycerin and papaverine, and direct magnification. Experience in 37 impotent patients demonstrates marked improvement in the quality of visualization of distal vessels, and the frequent presence of functional vasoconstriction of medium and small arteries that can be distinguished from organic disease only with vasodilators. We believe these angiographic methods will improve the criteria against which other diagnostic and therapeutic methods can be objectively assessed.

Adult↗
PubMed1987

Penile pharmacocavernosography and cavernosometry in the evaluation of impotence.

Within the past few years, veno-occlusion of the corpora cavernosa has become generally recognized as an essential prerequisite for adequate penile erection. Veno-occlusive incompetence is suspected to be a frequent cause of impotence. Our recent experience with cavernosography in two normal volunteers and 36 impotent patients indicates that angiography is reliable in evaluating the competence of the veno-occlusive mechanism only if both pharmacocavernosography (PCG) and pharmacocavernosometry (PCM) are applied. Twenty minutes after intracavernosal (IC) injection of a mixture of 60 mg. papaverine and one mg. phentolamine (regitine), 100 ml. of diluted radiographic contrast medium are infused at the rate of one or two ml./sec. while pressure is recorded, and radiographic films are exposed at the rate of one every eight to 15 seconds. PCM and PCG of the corpora cavernosa indicated the overall degree of competence of the cavernosal veno-occlusive mechanisms, and the sites of veno-occlusive incompetence; non-pharmacologic studies were unreliable in these regards. During non-pharmacologic infusion in normals, pressures rose to 40 to 45 mm. Hg, and free efflux could be visualized from multiple venous systems. After pharmacologic injection in normals, all venous channels closed, and pressures rapidly rose toward or above 200 mm. Hg, at which time the infusion was stopped. Veno-occlusive incompetence was defined angiographically when more than minimal efflux occurred during pharmacocavernosography from any venous system. The incompetence could involve the deep penile system, the deep dorsal system, or the spongiosal system, alone or in combination. Severe veno-occlusive incompetence was considered diagnostic of venogenic impotence, and was defined manometrically when IC pressures failed to exceed 100 mm. Hg during infusion of 100 ml. of fluid at 2 mm./second after IC papaverine and phentolamine injection. We believe these angiographic methods will improve the criteria against which other diagnostic and therapeutic methods can be assessed.

Adult↗
PubMed1986

Plasma and red cell lipids in alcoholics with macrocytosis.

The cholesterol and phospholipid content and the fatty acid composition in plasma and red cell membranes was determined in 10 alcoholics with macrocytic erythrocytes. None of the patients had anemia. Red cells exhibited macrocytosis up to 108 fl in all patients. Bilirubin, albumin, prothrombin, and cholinesterase were in the normal range, whereas transaminases and gamma-glutamyl transpeptidase activities in serum were elevated in most of the patients. The molar ratio cholesterol/phospholipids in red cells was not altered in alcoholics. An abnormally high ratio of saturated/unsaturated fatty acids was found in plasma as well as in red cell phospholipids from alcoholics. Linoleic acid was substantially decreased in plasma of alcoholics (controls 32.3%, alcoholics 21.8%). This fatty acid abnormality was reflected by a decrease of linoleic acid in red cell phosphatidylcholine. The present data may suggest that fatty acid changes taking place in membranes of macrocytes were a consequence of changes in the plasma and reflect plasma/membrane exchanges rather than direct effects of ethanol on red cell membranes. Lipid alterations of red cell membranes may be involved in the development of macrocytosis in chronic alcoholism.

Adult↗