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Biomedical subjects

D Cohen

Publications and source records attributed to D Cohen.

At least 19 recordsLinked to original sources
PubMed1979

Bicycle accidents in childhood.

From a total of 4589 accident cases reported from nine Sydney hospitals during 1978, 312 children, 50% of whom were five to nine years old, were injured while riding bicycles. An in-depth investigation of 139 cases showed that motor vehicles were involved on only three occasions; the children were injured as a result of inexperience and misuse. These results indicate the value of developing and implementing bicycle education programmes for younger children, especially those aged five to nine years. Equal emphasis should be given both to traffic safety instruction and to basic riding skills.

Accidents, Traffic↗
PubMed1979

[Demonstration of a soluble factor capable of inhibiting allogenic lymphocyte proliferation in man].

During the secondary mixed lymphocyte reaction (MLR), i.e. after the double in vitro allogenic sensitization between responding and stimulating cells bearing at least one HLA-DR incompatibility, suppressor cells are developed [1]. They are able to inhibit a primary MLR provided that the stimulating cells possess the same DR incompatibility as the immunizing cells. We report here that this inhibition is due to the production by these cells of a soluble suppressor factor which acts on responding cells provided that they share at least one gene product of the HLA-D region with the cells producing the factor. This a feedback process of auto-inhibition occurring after hyperimmunization. The action of this suppressor factor seems to be genetically restricted to an as yet unknown locus in linkage disequilibrium with HLA-DR.

Cell Division↗
PubMed1979

Smoking impairs long-term dust clearance from the lung.

The time for the long-term clearance of dust from human lungs was measured. Three heavy cigarette smokers and nine nonsmokers inhaled a harmless trace amount of magnetic dust, Fe3O4. From periodic measurements with a sensitive magnetic detector of the amount of this dust remaining in the lungs, a clearance curve was determined for each subject. This magnetic tracer method allows clearance to be safely followed for a much longer time than with radioactive tracer methods. The dust clearance in the smokers is considerably slower than in the nonsmokers. After about a year, 50 percent of the dust originally deposited remained in the lungs of the smokers whereas only 10 percent remained in the lungs of the nonsmokers. The smokers therefore retained five times more dust than the nonsmokers. This impaired clearance of Fe3O4 suggests impaired clearance in smokers of other dusts, such as toxic occupational and urban dusts. The higher retention of these dusts may contribute to the higher incidence of lung diseases in smokers.

Adult↗
PubMed1979

Effect of leukocyte hydrolases on bacteria. XV. Inhibition by antibiotics, metabolic inhibitors, and ultraviolet irradiation of the release by leukocyte extracts, trypsin, and lysozyme of lipopolysaccharide from gram-negative bacteria.

Leukocyte extracts, trypsin, and lysozyme are all capable of releasing the bulk of the LPS from S. typhi, S. typhimurium, and E. coli. Bacteria which have been killed by heat, ultraviolet irradiation, or by a variety of metabolic inhibitors and antibiotics which affect protein, DNA, RNA, and cell wall synthesis no longer yield soluble LPS following treatment with the releasing agents. On the other hand, bacteria which are resistant to certain of the antibiotics yield nearly the full amount of soluble LPS following treatment, suggesting that certain heatlabile endogenous metabolic pathways collaborate with the releasing agents in the release of LPS from the bacteria. It is suggested that some of the beneficial effects of antibiotics on infections with gram-negative bacteria may be the prevention of massive release of endotoxin by leukocyte enzymes in inflammatory sites.

Anti-Bacterial Agents↗
PubMed1979

Comparison of the magnetoencephalogram and electroencephalogram.

The spatial response of the magnetoencephalogram (MEG) to sources in the brain's cortex is compared with that of the electroencephalogram (EEG). This is done using computer modeling of the head which is approximated by 4 concentric spherical regions that represent the brain and surrounding bone and tissue. Lead fields are calculated at points on the cortex for unipolar, bipolar and quadrupolar MEG and EEG measurements. Since lead fields are patterns of the sensitivity of these measurements to a source at various locations and orientations, they provide a convenient means for comparison. It is found that a unipolar MEG has a very different lead field than a unipolar EEG. Hence, this type of MEG detects sources at different locations and orientations than this EEG. Although bipolar MEG and EEG lead fields are found to have similar patterns, the MEG lead field is narrower than that of the EEG and hence 'sees' a smaller area on the cortex than the EEG. This is because the potentials measured by the EEG are 'smeared' by the low-conductivity skull; the magnetic fields measured by the MEG are not smeared. Quadrupolar MEG and EEG lead fields are found to be about the same. The responses of bipolar MEGs and EEGs to distributed sources, which are composed of aligned and randomly oriented dipoles, are compared. It is found that for both types of sources, the MEG 'sees' an area on the cortex which is approximately 0.3 times that for the EEG. Hence, the MEG appears to be useful for detecting a more restricted group of sources than the EEG.

Brain↗
PubMed1979

Single case study. Pseudodementia and mania.

This case report extends the discussion of pseudodementia into the area of manic behavior. An elderly patient whose manic symptoms are considered to be an early sign of an organic brain syndrome should be given timely repeat evaluations before this diagnosis is allowed to guide treatment. Our case presentation emphasized the paucity of the data base we have to diagnose cognitive and emotional disturbances of the elderly. It is difficult to identify the essential features of cognitive dysfunction associated with primary neuronal degeneration especially in the early stages of the disease. A careful differential diagnostic evaluation is important to eliminate variables such as affective disorders and underlying physical conditions as causes of confusion and cognitive dysfunction in the elderly patient.

Bipolar Disorder↗
PubMed1979

Inhibition of host resistance by nutritional hypercholesteremia.

Previous experiments showed that nutritionally induced hypercholesteremia in mice caused an increase in susceptibility to coxsackievirus B, with a marked suppression of cellular infiltrates in infected tissues and an increased mortality. The present studies demonstrated that a hypercholesteremic diet was associated with an inhibition in host resistance as measured by susceptibility to Listeria monocytogenes infection and the growth of two transplanted syngeneic murine tumors. Moreover, the ability of Corynebacterium parvum to induce regression of a transplanted methylcholanthrene-induced fibrosarcoma was inhibited in hypercholesteremic hosts, as was the histiocytic infiltration normally accompanying C. parvum inoculation. In contrast, the peritoneal macrophages from C. parvum-treated hypercholesteremic mice were indistinguishable from similarly treated macrophages from normal mice with respect to their in vitro tumoricidal activity and the presence of a cell surface antigen associated with activated macrophages. Hypercholesteremia was also associated with a decreased antibody response to sheep erythrocytes in vivo, but dit not appear to exert a detrimental effect on B- or T-cell blastogenesis when tested in vitro. The findings that the hypercholesteremic diet was associated with an impairment in the host immune response and increased susceptibility to viral, bacterial, and tumor cell challenge are discussed with respect to virus-lipid interactions in the pathogenesis of atherogenesis and diabetes mellitus.

Animals↗
PubMed1979

Nonfatal graft-versus-host disease occurring after transfusion with leukocytes and platelets obtained from normal donors.

There have been two previous reports of fatal graft-versus-host (GVH) disease following transfusion of leukocytes from normal donors for the supportive care of leukemic patients. We have reported a nonfatal case of GVH disease in a child with acute monoblastic leukemia who received leukocyte and platelet transfusions from normal donors. The dose of lymphocytes contained in both leukocyte and platelet concentrates obtained with a semicontinuous-flow cell separator is sufficient to cause GVH disease. Irradiation of all blood products administered to severely immunocompromised and myelosuppressed patients should be considered.

Blood Transfusion↗
PubMed1978

Hypodiploidy and serum immunoglobulin concentrations in the elderly.

Chromosome analyses and Ig level determinations were carried out on seventeen aged men and women, 83--100 years of age. In men, significant correlations were found between hypodiploidy and IgA (gamma = 0.95) and between monosomy C and IgG (gamma = 0.79) while in women, monosomy G and IgG were significantly correlated (gamma = 0.73). The emergence of significant correlations between chromosome loss and Ig levels in this study provides support for a relationship between age-associated chromosomal changes in T cells and the immunologic response of B cells.

Aged↗
PubMed1978

Tracheobronchial secretions collected from intact dogs. II. Effects of cholinomimetic stimulation.

The effect of cholinomimetic stimulation on the quantity and composition of tracheobronchial secretions (TBS) collected from intact dogs was studied. After the administration of methacholine chloride, the collection rate of TBS increased over threefold within 10 min and returned to the control level by 50 min. Even though there was an increase in the total amount of protein collected, the protein concentration of the secretions decreased initially by 40%, returning to normal by 30 min. This was the result of an apparent dilution of the secretions by nonproteinaceous components. In addition, at 10 min, there was an increase in the protein associated with mucins. These responses were blocked by the preadministration of atropine. When TBS was separated into supernatant and pellet phases by centrifugation, we found that, following methacholine, there was a 35% increase in the ratio of albumin to IgG in the supernatant phase. These results suggest that the increased secretion due to methacholine may result, in part, by a selective filtration of fluid from the interstitial and/or vascular compartment(s) with proteins appearing in the secretory mixture based partially on their size.

Animals↗