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Biomedical subjects

D Cohen

Publications and source records attributed to D Cohen.

At least 757 records · Page 42Linked to original sources
PubMed1975

Effect of treatment with the MER tubercle bacilli fraction on the survival of mice carrying mammary tumour isografts: injections of MER at the tumour site or at a distal location.

Strain BALB/c female mice bearing syngeneic implants of 2 mammary adenocarcinomata were treated with MER, x-irradiation or both. MER was administered either subcutaneously at a site contralateral to the neoplastic growth or both into such a site and directly at the tumour location. None of the treatments effected cures but many of the treated animals survived significantly longer than did the saline injected controls. There was no evidence that introduction of MER into, or directly adjacent to, a tumour is a generally more efficacious route of administration than application at only a distal site and there was, indeed, the strong contrary impression that distal treatment alone bestowed survival protection more often and to a greater extent. In no instance was there a shortening of survival time following administration of MER at a location away from the tumour implant.

Adenocarcinoma↗
PubMed1975

Tuberculin sensitivity in a high-risk canine population.

An epidemiologic study of tuberculosis in dogs exposed to humans with recently reported tuberculosis was undertaken in Philadelphia between July 1966 and June 1968. A total of 29 dogs meeting the criteria for inclusion in the high-risk population were studied by history, physical examination, intradermal tuberculin tests, and radiographic and bacteriologic examination. Ten of the 29 dogs showed positive responses to US Department of Agriculture (USDA) standard mammalian tuberculin. Positive tuberculin tests to second strength PPD were demonstrated in five of the 10 responders to USDA mammalian tuberculin. No physical, radiographic or bacteriologic evidence of tuberculosis was found in any of the high-risk animals examined. In a comparison group of 70 dogs without knwon exposure to tuberculosis, two positive responses to USDA tuberculin were demonstrated and none to PPD.

Animals↗
PubMed1975

Relationships between Leaf Water Status, Abscisic Acid Levels, and Stomatal Resistance in Maize and Sorghum.

A new method for abscisic acid extraction and purification was developed to handle large numbers of small (about 125 milligrams fresh weight) samples of leaf discs. This method enabled short term changes in abscisic acid to be followed in single leaves.Water potentials, stomatal diffusion resistance, and abscisic acid levels were measured in the leaves of maize (Zea mays L. var. Wisconsin 575) and sorghum (Sorghum bicolor, hybrid NK 145) plants subjected to a drought-recovery cycle under controlled environmental conditions. The levels of abscisic acid began to rise, and the stomata closed, over a narrow range of water potential (-8 to -10 bars) in both species. Abscisic acid levels continued to rise after the stomata closed. The maximum amount of abscisic acid extracted from maize leaves was about twice that from sorghum, but this represented a similar proportional increase over the control level.In excised leaves little or no change in abscisic acid levels was found within 60 to 120 minutes after stress was applied (phase I). Subsequently abscisic acid levels rose rapidly to about 20 times the prestress level (phase II). Stomatal closure always preceded the phase II increase in abscisic acid.The aftereffects of stress differed in the two species. In sorghum control levels of both abscisic acid and stomatal resistance were regained within 24 hours of rewatering. In maize abscisic acid levels also fell rapidly, but regained control levels only after 48 hours. The resumption of normal stomatal functioning occurred after a further 24 hours.Impaired stomatal functioning after stress does not appear to be associated with high residual levels of abscisic acid in the leaf.

Journal Article↗
PubMed1975

Magnetic determination of the relationship between the S-T segment shift and the injury current produced by coronary artery occlusion.

Both the S-T segment shift and the injury current were measured using the direct-current magnetocardiogram (d-c MCG) in seven dogs undergoing coronary artery occlusion. The purpose of the measurements was to clarify the origin of the S-T shift in acute ischemia and infarction. Previous measurements, consisting of d-c electrograms recorded from the exposed epicardial surface in situ, are partially inconsistent; also, they are not necessarily representative of the surface electrocardiogram (ECG), which sums broadly over the myocardium. The d-c MCG allows steady myocardial currents in the intact torso to the measured externally; because the d-c MCG sums broadly over these currents, conclusions drawn from it are applicable to the ECG. Coronary artery occlusion was produced by inflating a tube which, about 1 week earlier, had been surgically installed around the artery and exteriorized. During occlusions carried out in the MIT magnetically shielded room, a sensitive magnetometer recorded the d-c MCG at various locations around the torso. Within 20 seconds after occlusion, equal and opposite S-T segment and base-line (d-c) shifts appeared on the d-c MCG; these shifts were maintained for at least 15 minutes, after which they slowly decreased. Therefore, during the acute ischemia produced by these occlusions, the S-T shift is a secondary result of a primary injury current that is interrupted during the S-T interval.

Animals↗
PubMed1975

Teratomas in childhood.

Of 107 teratomas in children, 86 were benign and 21 malignant. Sacrococcygeal and pelvic teratomas predominated (51 cases) and these fell into 3 groups: post sacral, dumb-bell and presacral. The 34 purely posterior tumours were always congenital and benign, whilst the incidence of malignancy in dumb-bell and presacral teratomas increased as the tumour became more internal. Malignant teratomas were carcinomas, usually containing glandular, papillary and clear-cell areas, and metastases were similar. Immature tissues in benign teratomas were usually neural or connective tissue. They did not give rise to neuroblastomas or sarcomas, and did not indicate a worse prognosis. Only 2 originally benign teratomas later developed malignancy.

Adolescent↗
PubMed1975

Lipoprotein lipase of ovarian follicles in the domestic chicken (Gallus domesticus) (38537).

A lipase, bearing the characteristics of adipose tissue lipoprotein lipase (LPL) has been characterized in avian ovarian granulosa cells. The activity is low in cells from follicles weighing less than 0.5 g; in heavier follicles which have entered the rapid growth phase, significant activity (1 mumole fatty acid/mg protein/hr) could be identified. Granulosa LPL provides follicular tissues with the requisite enzyme system to hydrolyze very low density lipoprotein triglyceride en route to the oocyte.

Adipose Tissue↗
PubMed1975

Effects of methanol extraction residue and therapeutic irradiation against established isografts and simulated local recurrence of mammary carcinomas.

Female BALB/c mice carrying established isografts or simulated local recurrence implants of 2 rapidly growing mammary adenocarcinomas were treated either by injection of the methanol extraction residue (MER) fraction of killed Bacillus Calmette-Guérin organisms (given s.c. or into the tumor) or by focal X-irradiation or by both. None of the modalities of therapy effected cures, but in many instances there was a significant retardation of tumor cevelopment and prolongation of the lives of the mice. Administration of MER alone offered protection in a number of cases but less often than the other forms of treatment. Combined therapy with MER and irradiation was, on the whole, the most successful therapeutic intervention. MER or irradiation administered alone enhanced the neoplastic process only on rare occasions; this appeared to be the case even more infrequently with combined treatment. MER was most likely to be effective alone or in combination when small quantities were used and when only 1 treatment or 1 cycle of combined therapy was given. The therapeutic action of MER was not dependent on direct introduction of the agent into a neoplastic focus; s.c. administration distal to the tumor site was almost always at least as satisfactory as injection directly into the tumor mass and indeed was often more efficacious.

Adenocarcinoma↗
PubMed1974

Cellular and ultrastructural changes in mesophyll and bundle sheath cells of maize in response to water stress.

Ultrastructural changes were correlated with leaf water potential, relative water content, and abscisic acid levels in the leaf. Mesophyll cells were more prone to damage than bundle sheath cells at a leaf water potential of -18.5 bars. Tonoplast breakdown and cell disruption occurred in 25% of the mesophyll cells. On rewatering, these disrupted cells did not recover. In bundle sheath cells, starch, lost at about -13.5 bars leaf water potential, reappeared within 2.5 hours of rewatering.

Journal Article↗
PubMed1973

Perfluorocarbons having a short dwell time in the liver.

Perfluorinated organic liquids are useful as high capacity oxygen and carbon dioxide solvents. After intravenous infusion most of these perfluorinated emulsions are deposited in the liver and spleen in a matter of days, where they remain for the lifetime of the animal. Hence, while they may be useful as isolated organ perfusion media their value as artificial blood is limited. A family of perfluorocarbons has now been discovered, which, although deposited in the liver after circulation in the blood, leave the liver to be excreted via the lungs and skin in a matter of days without apparent harmn to the animal.

Animals↗
PubMed1973

Ferromagnetic contamination in the lungs and other organs of the human body.

Contaminating particles which are ferromagnetic have been found in the human body. Their distribution was measured by applying an external magnetic field to the torso for a short time, and then, in a shielded room, mapping the steady magnetic field around the torso due to the magnetized particles. Maps of subjects show various distributions, including particles in the stomach from food cans and in the lungs from are welding. The fields from these two sources are strong enough to be detected with a flux-gate magnetometer, without the need for a shielded room. This simplicity of detection of larger amounts of ferromagnetic contamination suggests that this method may be used in two applications: in detecting the presence of large amounts of asbestos (ferromagnetic and harmful) in the lungs of asbestos workers, and in tests of the condition of the lung where FE(3)O(4) dust (ferromagnetic and harmless) would be used as an inhaled tracer material.

Asbestos↗