Biomedical subjects
Publications and source records attributed to D Gordon.
A special device adapted to a Nikon projection vertexometer permits the power to be measured in the periphery of ophthalmic lenses. The marginal power can be measured with respect to the vertex sphere. Various values of the vertex sphere radius can be obtained with this instrument. The characteristics of this modified focimeter are described in this paper.
Ten closely related tumor-promoting and nonpromoting, proinflammatory phorbol derivatives were tested for stimulation of [3H]thymidine ( [3H]TdR) incorporation into human mononuclear cells. Co-mitogenic activity was assessed with maximally effective concentrations of phytohemagglutinin (PHA) or mixed-lymphocyte reactions (MLR) in the presence of phorbol esters. Tetradecanoyl phorbol acetate (TPA), two 4-deoxyphorbol esters, and two 12-deoxyphorbol monoesters stimulated [3H]TdR incorporation in a dose-related manner. Two established nonpromoting 12-deoxyphorbol diesters were also mitogenic, although less effective than TPA, and produced lower maximal responses. TPA, the 4-deoxyphorbol esters, the 12-deoxyphorbol monoesters, and the two nonpromoting diesters were able to increase MLR-induced incorporation to the same level. When conditions were used where PHA and phorbol esters were optimally mitogenic, inhibition resulted. With the exception of co-mitogenic activity of the nonpromoting diesters, the mitogenic, co-mitogenic, and PHA-inhibiting activities were correlatable. Phorbol, a 4 alpha-deoxyphorbol ester, and resiniferatoxin had no effects. Mitogenic activity of the phorbol esters was inhibited by dexamethasone, chloroquine, and p-bromophenacyl bromide. TPA, the 4-deoxyphorbol esters, and the 12-deoxyphorbol monoesters were resistant to inhibition of activity by cyclosporin A, whereas the noncorrelating diesters exhibited sensitivity to cyclosporin A inhibition comparable to that of PHA. MLR-induced [3H] TdR incorporation was susceptible to cyclosporin A, but the phorbol ester-enhanced responses were cyclosporin A-resistant.
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To examine the relative importance of intrauterine growth failure, extrauterine growth failure before or after term, and the prognostic significance of catch-up growth, 192 very low--birth weight infants (less than 1.5 kg) were followed prospectively to 8 months corrected age. One hundred fifty-four appropriate--for--gestational age (AGA) and 38 small--for--gestational age (SGA) infants were categorized into normal and subnormal (less than -2 SD) weight for age groups at term (40 weeks) and at 8 months corrected age. By term, 71 AGA infants had subnormal weight; 41 of these caught up by 8 months, and an additional 13 AGA infants failed to thrive between term and 8 months. Of the SGA infants, three caught up in weight by term, and an additional 16 caught up by 8 months. Significant correlates of subnormal weight included neonatal risk score, incidence of chronic disease, and extended hospitalization. The AGA and SGA infants who failed to thrive or failed to catch up in weight by 8 months had lower mean Bayley developmental quotients (p less than 0.005), smaller head circumferences (p less than 0.005), and a higher rate of neurosensory impairment (p less than 0.01) than the AGA infants with normal fetal and postnatal growth. Intrauterine and/or postnatal growth failure prior to term was not of sinister prognostic significance if catch up occurred thereafter.
(1) A synaptosomal fraction obtained from locust nervous tissue has been shown to possess an active gamma-aminobutyric acid transport mechanism. This activity is preserved and even enriched by the membrane vesicles derived from osmotically shocked synaptosomes. (2) Electron-microscopy examination indicates that the above membrane vesicles are derived predominantly from the neuronal plasma membrane and are devoid of any internal cellular organelles and components. Active transport of gamma-aminobutyric acid into these vesicles has been demonstrated with artificially imposed ion gradients as the sole energy source. (3) gamma-Aminobutyric acid transport can be driven by an Na+ gradient (out greater than in) and/or by a gradient of Cl- (out greater than in). This process is absolutely dependent on the simultaneous presence of both types of ion in the external medium. The stimulation of the process by valinomycin indicates that gamma-aminobutyric acid transport is an electrogenic process which is stimulated by a membrane potential (interior negative).
The effect of a synchronizing-recruiting drug schedule vs. myelotoxic therapy on remission rate and of Bacillus Calmette-Guerin on remission duration and survival of adults with acute myelogenous leukemia were studied in a prospective cooperative trial. After randomized remission induction with Arabinosyl Cytosine + vincristine + methotrexate + leucovorin (AVML), thioguanine + Ara-C + Daunorubin (TAD), or Daunorubicin + Ara-C (DA), complete remissions (CR) were consolidated with TAD or AVML. CRs were maintained with BCG vaccination (Tice strain) by the tine technique, or BCNU plus Ara-C (B/A), or no further therapy (NFT). Of 209 evaluable TAD patients, 105 (50%) achieved CR; of 187 DA, 97 (52%) achieved CR. AVML yielded only 15 CR among 59 patients (25%). The time to remission was significantly shorter with DA compared with TAD. Ninety-seven patients were randomized to maintenance therapy (35 B/A, 30 BCG, 32 NFT). There were no differences in remission duration (7, 8, 6 months) or survival (16, 22, 16 months, respectively). Manipulation of the cell cycle, as employed in this study, was not helpful. There may be a marginal effect of BCG, but our data fail to show a statistically significant benefit.
Terminal transferase (TdT) activity and antigen have been measured in 267 specimens of human bone marrow and peripheral blood by using a biochemical assay for enzymatic activity and an immunofluorescence test for antigen. Oligo p(dA)50 and dGTP were used as reagents in the biochemical assay and either rabbit anti-calf TdT or rabbit anti-human TdT was used as the primary antibody for immunofluorescence. Because both false-positive and false-negative detection of TdT antigen occurs, the biochemical assay of TdT activity is considered the standard against which immunofluorescence assays must be measured. If specimens of cells contained TdT activity, then the immunofluorescence detected antigen in 91% of cases (rabbit anti-calf TdT) and 95% of cases (rabbit anti-human TdT). When no TdT activity was detected, the immunofluorescence test was positive in 7.8% of cases (rabbit anti-calf TdT) and 5.2% of cases (rabbit anti-human TdT). When air-dried slices were shipped by air mail to a distant location before being stained for immunofluorescence, TdT antigen was detected in only 33% of matched pair cases which contained TdT activity. From this study, the authors conclude that with current methodology, immunofluorescence tests for TdT antigen must be carried out on slides prepared in the testing laboratory and that such tests are reliable in more than 90% of cases. However, because a small percentage of results are false positives and false negatives, the authors suggest that if a patient's clinical response is not consistent with the immunofluorescence TdT result, an enzymatic assay for TdT activity be carried out.
A case of prolymphocytic leukemia was studied by using light and electron microscopy, cytochemistry and multiple immunological markers for T and B lymphocytes. Cytochemical and immunological studies showed that the cells were T-lymphocytes. By using monoclonal antibodies to human T-cell subsets, we found that these cells had the T-helper cell phenotype. The usefulness of multiparameter studies in subclassifying T-cell malignancies is discussed and the literature on T-prolymphocytic leukemia reviewed.
The inter-electrode resistance during ECT is shown to be very variable, a finding which invalidates the measurement of shocks in joules. With square wave pulses of selected current value the threshold for convulsion may be below 100 milliamperes or above 2,000 milliamperes. It is advisable to measure the current value during millisecond pulses with relatively long intervals between.
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Power spectrum analysis of heart rate fluctuations provides a quantitative noninvasive means of assessing the functioning of the short-term cardiovascular control systems. We show that sympathetic and parasympathetic nervous activity make frequency-specific contributions to the heart rate power spectrum, and that renin-angiotensin system activity strongly modulates the amplitude of the spectral peak located at 0.04 hertz. Our data therefore provide evidence that the renin-angiotensin system plays a significant role in short-term cardiovascular control in the time scale of seconds to minutes.
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Accurate quantitation from the bone scan image of skeletal uptake of radiopharmaceutical would be of value in the assessment of patients with metabolic bone disease. Repeat measurements of bone to soft tissue (B/ST) ratios on the one set of images were made for 103 subjects, a) by the same observer using lumbar vertebra 2 for the area of bone; b) by the same observer using lumbar vertebra 2 then lumbar vertebra 4; c) by two observers both using lumbar vertebra 2. The median difference between repeat measurements by the same observer was well under 1% but the 5-95 percentile range was -13 to +14%. Between the two observers there was a median difference of 10.6% with a 5-95 percentile range of -11 to +44%. We also measured B/ST ratios in 150 control subjects and 139 patients with various metabolic bone disorders. While statistically significant differences for B/ST ratios were found between the osteomalacia, renal osteodystrophy, Paget's groups, and the control population (P less than 0.001 in all cases), there was appreciable overlap between individual patient results and the control range. It is concluded, therefore, that measurement of B/ST ratios for the individual is of limited value in clinical practice.
Ethanol and three beverage alcohols were examined for their effects on the aggressive responses of the convict cichlid. At an ethanol concentration that gave negligible effects on the basal level of these responses, rum was observed to depress aggression. As its concentration of acetaldehyde was significantly higher than that of the other beverage alcohols, we assessed the effects of acetaldehyde on the aggressive responses, as well as the locomotor activity of the fish. At 4 mg/l, acetaldehyde completely inhibited aggressive responses, without affecting locomotor activity. It is likely, however, that acetaldehyde does not explain the entire inhibitory effect of rum on the aggressive responses of the cichlid.
Eighteen patients undergoing bench surgery and autotransplantation are reported. The major indications for this procedure are renovascular hypertension and neoplasms affecting either both kidneys or a solitary kidney. The least satisfactory results were obtained when calculus disease was present.
Presenting a totally new approach to the effective treatment of Atherosclerosis through the alteration of biophysical properties both "intracellularly" and "extracellularly." The experimental data is preliminary but the results obtained indicate that by allowing the atherosclerotic lesions to take up the magnetically excitable submicron particles and then applying an external alternating electromagnetic field, the atherosclerotic lesions may be selectively resolved without damaging normal blood vessels. This concept suggests many areas of investigation since there are a variety of means of biophysically altering the atherosclerotic plaques, and many substances may be utilized to enhance the process. This new technology and this initial experimentation introduces a "new era" in the effective treatment of Atherosclerosis.
1. The electrolyte and water composition of urine and ileal fluid was studied in six patients with ileostomies during dietary sodium deprivation and at the same time measurements were made of plasma renin activity, plasma aldosterone concentration, renal aldosterone excretion and plasma arginine vasopressin concentration. 2. In each subject there was a reduction in renal sodium excretion within 24 h of sodium deprivation. Significant rises in plasma renin activity, plasma aldosterone concentration and renal aldosterone excretion occurred by day 2 of sodium deprivation. 3. There was only modest conservation of sodium by the ileum during sodium deprivation, but ileal potassium concentration rose progressively. There were significant associations between ileal-fluid potassium concentration and plasma renin activity or renal aldosterone excretion. 4. Under the conditions of the experiment a diuresis was observed in each subject during dietary sodium deprivation. This did not appear to depend on changes in plasma arginine vasopressin concentration.
1 The effects of histamine and chemical analogues were examined on mitogen-stimulated human lymphocyte proliferation. 2 Compounds with selective agonist activity at either H1- or H2-receptors were found to inhibit proliferative responses, although N-3-methyl-histamine which does not act on either receptor was as inhibitory as histamine itself. 3 The H2-receptor agonist, dimaprit, had a profound inhibitory effect on proliferation, however nordimaprit, which has little or no H2-agonist activitiy, was more active on lymphocytes. Impromidine, although a potent H2-agonist, failed to produce such inhibition. 4 The effects of dimaprit and nordimaprit were not reversed by H2-receptor antagonists, cimetidine or metiamide. 5 These results do not support the view that the antiproliferative effects of histamine and related compounds are mediated via conventional H1-or H2-receptors. 6 SKF 93390 was found to be the most active of the dimaprit analogues tested, which could represent a novel series of potential immunosuppressive agents.