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Biomedical subjects

M Kessler

Publications and source records attributed to M Kessler.

At least 343 records · Page 19Linked to original sources
PubMed1986

Dose volume histogram analysis of liver radiation tolerance.

Eleven patients with carcinoma of the pancreas or biliary system received heavy charged particle radiation treatments and whole liver heavy charged particle radiation at Lawrence Berkeley Laboratory. Doses to the whole liver ranged from 10 to 24 Gray-equivalent (the biological equivalent of 10 to 24 Gray of low-LET photon radiation), whereas the dose to the primary lesion ranged from 53.5 to 70 Gray-equivalent (GyE). The fraction size was 2 to 3 GyE. The liver received partial as well as whole organ irradiation. Integral dose volume histograms for the liver were obtained in all 11 patients. An integral dose volume histogram displays on the ordinate the percentage of liver that was irradiated in excess of the dose specified on the abcissa. In this study, the clinical liver radiation tolerance of these patients is correlated with the information contained in an integral dose volume histogram. One patient developed radiation hepatitis. The integral dose volume histogram of this patient differed from the dose volume histograms of the other 10 patients. This difference was greatest in the range of doses between 30 and 40 GyE. Our results suggest that liver doses in excess of 30 to 35 GyE should be limited to 30% of the liver or less when 18 GyE of whole liver radiation is delivered at 2 GyE per fraction in addition to primary radiation of the pancreas or biliary system.

Helium↗
PubMed1986

Studies on retrograde and anterograde amnesia of olfactory memory after denervation of the hippocampus by entorhinal cortex lesions.

The effect of hippocampal denervation on olfactory memory in rats was tested after interrupting the lateral olfactory tract projections at the level of the entorhinal cortex. When lesioned animals were trained to learn new odors, they showed no evidence of retention 3 h after acquisition. These results confirm earlier data on rapid forgetting in rats after hippocampal deafferentation and are in parallel to the anterograde amnesia typically found in humans with hippocampal damage. On the other hand, preoperatively learned information was minimally impaired after hippocampal deafferentation even if it was acquired within less than 1 h before the lesion. This finding differs from reports on humans as well as monkeys with hippocampal damage where memories formed during a critical time span of months or even years before the lesion are found to be impaired. This may suggest that the consolidation process in humans and rodents has different time scales or that the roles of the human and the rat hippocampal structure in memory formation are somewhat different.

Amnesia↗
PubMed1986

Histoimmunological discrepancies in primary IgA nephropathy and anaphylactoid purpura sustain relationships between mucosa and kidney.

Immunohistomorphometric analysis of the tonsils from a series of patients with anaphylactoid purpura or Berger's disease showed abnormal proportions of gamma- and alpha-isotype-producing cells. Conversely, renal immunofluorescence (IF) performed on kidney biopsies from 2 patients with hematuria and clinical symptoms suggestive of one or the other of these conditions failed to confirm the suspected diagnosis. Immunohistomorphometric analysis of these patient's tonsils showed normal proportions of gamma- and alpha-isotype-producing cells. These negative results suggest that strong relationships exist between mucosal abnormalities and renal deposition of IgA in hematuria.

Adult↗
PubMed1986

Induction of glutamate binding sites in hippocampal membranes by transient exposure to high concentrations of glutamate or glutamate analogs.

The number of Na+-independent, Cl--dependent glutamate binding sites in rat hippocampal membranes is increased two- to fourfold after pre-exposing isolated membranes or hippocampal slices to high concentrations (0.1-10 mM) of L-glutamate or of glutamate analogs with high affinity for this binding site, such as quisqualate, homocysteate, or aminoadipate. N-Methylaspartate and kainate are ineffective. A similar binding increase is induced by transient exposure to the dipeptide tyrosylglutamate. The newly induced binding sites appear to be identical with pre-existing Cl--dependent binding sites by several criteria: They have a similar pharmacological profile, they are sensitive to low concentrations of Na+, and the number of sites can be further increased by transient exposure to micromolar calcium concentrations. Moreover, binding of [3H]APB, a ligand selective for the Cl--dependent glutamate binding sites, is also increased after glutamate preincubation. The induction of binding sites by high glutamate concentrations, described herein, is calcium-independent, not inhibited by leupeptin and, therefore, different from the previously described activation of binding sites by a calcium-sensitive protease. The high concentration of ligand needed to induce increased binding suggests the presence in hippocampal membranes of a binding site with low, millimolar affinity that is functionally related to the known high-affinity binding sites. Several interpretations of the observed effects and their implications for the possible relationship between the binding site and the synaptic receptor are discussed.

2-Amino-5-phosphonovalerate↗
PubMed1986

[Hemorrhagic fever with renal syndrome. Apropos of 13 cases observed in Lorraine].

Thirteen cases of hemorrhagic fever with renal syndrome (HFRS) have been observed in the Nancy area. Ten occurred during the summer of 1983 and three in April and May 1985. The clinical characteristics were in each case very typical: abrupt onset with high fever, myalgia, intense lumbar and abdominal pain, pulsatile headache, inflammatory syndrome, WBC count increase and thrombocytopenia. Acute renal failure occurred a few days later with oliguria (9 cases out of 13), massive proteinuria (9/13) and hematuria (6/13). All patients recovered without sequelae within 8-10 days. Renal biopsy performed in 8 patients showed slight tubular lesions with interstitial mononuclear cell infiltrate, congestion and diffuse interstitial edema, and in 2 cases hemorrhagic extravasation. No glomerular lesions were observed. Clinical, histological and epidemiological characteristics of these 13 French cases are highly similar to those of the Scandinavian Nephropathia Epidemica reports. The epidemiology of HFRS remains unclear as do its pathophysiological mechanisms.

Adult↗
PubMed1986

[Comparative cutaneous measurement of oxygen pressure (pcuO2) in healthy individuals and in patients with progressive scleroderma].

A modified method combining the two methods of measuring either tissue oxygen tension (pO2) or transcutaneous pO2, which have already been proven in other clinical fields, is presented for application in particular skin diseases. This so-called "cutaneous pO2 measurement" (pcuO2) is based on measurements from commercially available transcutaneous pO2 devices, but produces moderate hyperemia through the lower electrode temperature (e.g., 40.5 degrees C) instead of maximal hyperemia (by 44 degrees-45 degrees C temperature). Values obtained this way depend more upon local skin properties, including peripheral capillary flow, than on the arterial pO2. Thus the data are termed cutaneous pO2 (pcuO2). With this method, over 140 measurements were carried out on 14 healthy subjects and 14 patients with progressive systemic scleroderma (PSS); the measurements were made at various skin sites (interdigital fold II/III, back of mid-hand) and under different conditions (3-min upper arm arterial occlusion, 5-min arm muscle activity, cold stimulus to fingers). The pcuO2 values obtained from the PSS patients were significantly below (0-15 mm Hg) those from the healthy subjects (15-42 mm Hg). Fall and recovery times for pcuO2 (during and after arterial occlusion) were prolonged about twice as long in the patients. The pcuO2 reactions to muscle activity and cold stimulus were also significantly delayed in the patients as compared to the subjects. The modified method of cutaneous oxygen tension measurement presented can be employed for more precise assessment of the degree and severity of vascular disorder in PSS, and it is complementary to other clinical methods.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Restoration of T cell responsiveness to interleukin-2 in recipients of pancreatic islet xenografts treated with cyclosporine.

The immunosuppressive mechanism of cyclosporine (CsA) was studied using pancreatic islet xenotransplantation. A dose of 40 mg/kg/day CsA significantly prolonged survival of hamster islet grafts in BDE rats to 14.0 +/- 7.1 days compared with 2.0 +/- 0.9 days in controls (P less than 0.01), and antihamster lymphocytotoxic antibody was not detected in recipient sera even after rejection. Responses of spleen cells to pokeweed mitogen (PWM) and to phytohemagglutinin (PHA) were inhibited at least 21 days after transplantation in recipients treated with CsA. The addition of exogenous interleukin-2 (IL-2) to spleen cell cultures on day 7 had no effect on the impaired response to PHA. At the time of graft rejection (day 14), the T cell response to PHA recovered with the addition of IL-2. However, significant changes were not observed in the ratio of spleen cell subpopulations, which were studied with monoclonal antibodies of W3/ 13, OX-12, W3/25, and OX-8. From these results we conclude that CsA can significantly prolong islet xenograft survival in closely related species, and inhibit the production of humoral antibodies and T cell responses. At the time of graft rejection, recipient T cell responsiveness to IL-2 was restored. This suggest that islet xenograft rejection is caused by the recovery of cellular immunity in recipients treated with CsA.

Animals↗