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Biomedical subjects

M Wilson

Publications and source records attributed to M Wilson.

At least 649 records · Page 36Linked to original sources
PubMed1983

A sign-reversing pathway from rods to double and single cones in the retina of the tiger salamander.

Signal transmission between rods and cones was studied by passing current into a rod and recording the voltage response in a nearby double or single cone and vice versa. Two types of rod-cone interaction were found. Between immediately adjacent rods and cones, passage of current into either receptor elicited in the other receptor a sustained voltage response of the same sign as the injected current. These signals were still seen in the presence of Co2+, and are probably mediated by the electrical synapses which have been seen anatomically between adjacent rods and cones. In addition to this short-range sign-preserving interaction, passing current into a rod elicited a transient sign-inverted signal in cones up to at least 80 micron from the injected rod. No such response was seen in rods for current injection into cones. This signal was greatly reduced by Co2+ ions. Hyperpolarization of the cone to about -65 mV, with about 0.1 nA current, reversed this signal, which is presumed to be mediated by a chemical synaptic input to cones. Light flashes suppressed the sign-inverted signal for a period which was longer for brighter flashes. The time of reappearance of the signal was correlated with the return of the rod and horizontal cell potentials to their dark levels. This suppression could also be produced by an annulus of light which produced no light response in the receptors at the centre of the annulus, but which did polarize horizontal cells under the centre of the annulus. The wave form of the sign-inverted signal was similar to that produced in horizontal cells by current injection into rods, but of opposite sign. If an electrode was left in a cone for some time, the normal hyperpolarizing light response diminished, leaving a depolarizing response produced, presumably, by feed-back from horizontal cells. This signal was reversed when the cone was hyperpolarized with about 0.1 nA current. These data suggest that the sign-inverted response is mediated by feed-back from horizontal cells and, assuming that depolarization increases the rate of release of horizontal cell synaptic transmitter, then the feed-back transmitter opens channels in the cone membrane whose currents have a reversal potential around -65 mV.

Action Potentials↗
PubMed1983

New form of familial Parkinson-dementia syndrome: clinical and pathologic findings.

We studied a family in which three siblings had a syndrome characterized by parkinsonism features, mental deterioration, pyramidal signs, and abnormal eye movements beginning in the third decade. The pathology resembled that of progressive supranuclear palsy or the Parkinson-dementia complex of Guam, but these were excluded by the clinical presentation. This syndrome appears to be a new entity.

Adult↗
PubMed1983

National case-control study of Kaposi's sarcoma and Pneumocystis carinii pneumonia in homosexual men: Part 2. Laboratory results.

The Centers for Disease Control conducted a case-control study to investigate an outbreak of Kaposi's sarcoma and Pneumocystis carinii pneumonia in homosexual men. The occurrence of these diseases was found to be associated with certain aspects of lifestyle, including a greater number of male sex partners per year, exposure to feces during sex, history of syphilis and non-B hepatitis, treatment for enteric parasites, and use of various illicit substances. Laboratory studies reflected both this lifestyle and the probable underlying cause of the Kaposi's sarcoma and P. carinii pneumonia--cellular immune deficiency. Patients were found to have lymphopenia, specifically a deficiency of the T-helper subpopulation, resulting in a reversal of the T-helper to T-suppressor ratio. Levels of IgG and IgA were increased. When compared with controls, patients were also found to have significantly higher titers of antibody to Epstein-Barr virus and cytomegalovirus, a higher prevalence of antibody to hepatitis A virus and Treponema pallidum, a lower prevalence of antibody to varicella zoster virus, and a higher frequency of isolation of cytomegalovirus.

Acquired Immunodeficiency Syndrome↗
PubMed1982

Reconstitution after transplantation with T-lymphocyte-depleted HLA haplotype-mismatched bone marrow for severe combined immunodeficiency.

Severe combined immunodeficiency (SCID) is potentially correctable by bone marrow transplantation if a patient has a suitable histocompatible donor. In the absence of an HLA-matched donor, lethal graft-versus-host disease (GVHD), which is mediated by alloreactive donor T cells, may occur. In an attempt to prevent GVHD in one SCID patient lacking a matched donor, we treated maternal haplomismatched bone marrow with a unique nonmitogenic T-cell-specific monoclonal antibody (anti-T12) and complement to remove mature T cells. Despite the removal of greater than 99% mature T cells, the child developed significant life-threatening GVHD, which was terminated by a 5-day course of intravenous anti-T12. Subsequently, immune reconstitution occurred by 6 wk: the mature circulating T cells proliferated in response to soluble and allo-antigens in vitro and provided help for B-cell immunoglobulin synthesis. The patient was removed from a protective environment and discharged without evidence of further infection. Both HLA and chromosomal analyses showed that the circulating cells in the patient were of maternal origin. More importantly, the maternal T cells were no longer reactive with recipient cells. Mixing experiments indicated that the state of tolerance that resulted in this chimera was not due to active suppression. We conclude that HLA-mismatched transplantation for SCID can be undertaken if mature alloreactive donor T lymphocytes are depleted before and after bone marrow grafting.

Antibodies, Monoclonal↗
PubMed1982

The properties of single cones isolated from the tiger salamander retina.

1. The properties of isolated single cones were studied using the voltage-clamp technique, with two micro-electrodes inserted under visual control.2. Single cones had input resistances, when impaled with two electrodes, of up to 270 MOmega. This is probably lower than the true membrane resistance, because of damage by the impaling electrodes. The cone capacitance was about 85 pF.3. The cone membrane contains a time-dependent current, I(B), controlled by voltage, and a separate photosensitive current.4. The gated current, I(B), is an inward current with a reversal potential around -25 mV. It is activated by hyperpolarization over the range -30 to -80 mV, and at constant voltage obeys first order (exponential) kinetics. The gating time constant is typically 50 ms at the resting potential of -45 mV, rises to 170 ms at -70 mV, and decreases for further hyperpolarization.5. The spectral sensitivity curve of the cone light response peaks at 620 nm wave-length, and is narrower than the nomogram for vitamin A(2)-based pigments. The light responses of isolated cones are spectrally univariant.6. Voltage-clamped photocurrents were recorded at various membrane potentials, for light steps of various intensities. The photocurrent reversed at around -8 mV. The time course of the photocurrent, for a given intensity, was approximately independent of voltage (although its magnitude was voltage-dependent). The shape of the peak current-voltage relation of the light-sensitive current was independent of light intensity (although its magnitude was intensity-dependent).7. These results can be explained if: (a) light simply changes the number of photosensitive channels open, without altering the properties of an open channel; (b) the reactions controlling the production of internal transmitter, the binding of internal transmitter to the photosensitive channels, and the closing and opening of the channels are unaffected by the electric field in the cone membrane, even though at least some of these reactions take place in the membrane.8. I(B) plays only a small role in shaping the cone voltage response to light.

Ambystoma↗
PubMed1982

Changes in active and inactive renin throughout normal pregnancy.

Active and inactive renin were measured sequentially in 16 women throughout pregnancy and again post-partum. By 12 weeks, inactive renin was elevated 14-fold and fell slightly thereafter. By 12 weeks, active renin was 3.5-fold elevated. It continued to rise in 8 patients (Group A) until term, it remained stable in 6 (Group B) and in 2 it was quite variable. Between 12 and 32 weeks PRA and plasma aldosterone increased in Group A from 7.0 to 17.1 ng/ml/hr, and 20.0 to 95.7 ng/dl respectively and both were unchanged in Group B (6.5 to 8.1 ng/ml/hr and 26.5 to 24.6 ng/dl respectively). Inactive renin was higher in Group B than in Group A at 12 weeks (224 v 126 ng/ml/hr) but fell thereafter to the same stable but elevated level. Group A were younger (24 +/- 1.8 S.E. v. 30 +/- 2.2 years). These studies demonstrate that active and inactive renin increase early in pregnancy and remain elevated thereafter. In certain younger subjects, further increases in active renin and aldosterone sometimes occur and appear necessary for the maintenance of normal blood pressure.

Enzyme Activation↗