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Biomedical subjects

M Brown

Publications and source records attributed to M Brown.

At least 541 records · Page 30Linked to original sources
PubMed1988

Epidural injection of xylazine for perineal analgesia in horses.

Local anesthetics given in the epidural space of a horse may cause hind limb weakness in addition to analgesia. Because alpha 2 agonists given by epidural injection cause sensory blockade without motor effects in human beings and other species, their use in veterinary anesthesia is appealing. This study was designed to examine the effectiveness of xylazine HCl, an alpha 2 agonist commonly used in horses. Xylazine, 0.9% NaCl, and lidocaine were given by epidural injection to horses subjected to perineal electrical stimulation. Administration of xylazine (0.17 mg/kg of body weight, diluted to a 10-ml volume, using 0.9% NaCl) induced approximately 2.5 hours of local analgesia without apparent side effects. Higher doses of xylazine caused mild hind limb ataxia. Administration of lidocaine induced a similar duration of analgesia, with severe hind limb ataxia (100% incidence). We concluded that xylazine given by epidural injection results in safe, effective perineal analgesia in horses.

Analgesia, Epidural↗
PubMed1988

The IL-4 gene maps to chromosome 11, near the gene encoding IL-3.

IL-4/B cell stimulatory factor 1 (IL-4) is a potent mediator of the growth and differentiation of cells of most hemopoietic lineages. IL-4 is one of a number of lymphokines produced by T cells after activation with Ag or mitogen. In order to map the chromosomal location of the IL-4 gene, Chinese hamster-mouse somatic cell hybrids were used in Southern blot analyses with an IL-4 cDNA probe. These results suggested that the IL-4 gene was located on chromosome 11. In contrast, the gene encoding IL-2 was localized to either chromosome 1 or 3. The identification of a strain-specific Bgl II restriction enzyme polymorphism in the IL-4 gene was used to map the IL-4 gene to a position on mouse chromosome 11 within 1 centimorgan of the gene encoding IL-3.

Animals↗
PubMed1988

IL-4/B cell stimulatory factor 1 stimulates T cell growth by an IL-2-independent mechanism.

Resting T cells are stimulated to synthesize DNA by IL-4 and phorbol myristate acetate (PMA). This response of T cells to IL-4 plus PMA is independent of the action of IL-2 as judged by 1) the lack of IL-2 in supernatants of stimulated cells, 2) the failure to detect IL-2 mRNA in stimulated cells by in situ hybridization, 3) the inability of anti-IL-2R antibody and of anti-IL-2 antibody to block responses to IL-4 plus PMA, and 4) the failure of cyclosporin A to block responses. T cells also respond to anti-CD3 antibodies and IL-4 in the presence of anti-IL-2R antibodies. IL-4 stimulation of growth of the long term T cell line HT-2 also appears to be independent of the action of IL-2. No IL-2 mRNA is found in IL-4-stimulated HT-2 cells by Northern blotting; the response of HT-2 cells to IL-4 is not blocked by anti-IL-2R antibodies; the response of HT-2 cells to IL-4 is not inhibited by cyclosporin A. Although IL-4 stimulation of T cells is independent of IL-2, IL-4 plus PMA treatment of resting T cells does cause enhanced expression of IL-2R and prepares cells to proliferate to IL-2 alone. In both these properties IL-4 resembles IL-2. These experiments lead us to conclude that IL-4 can act as an alternative to IL-2 as authentic T cell growth factor.

Animals↗
PubMed1988

Activated suppressor cell function in multiple sclerosis--clinical correlations.

Activated suppressor cell function mediated by either freshly isolated peripheral blood mononuclear cells (MNCs), freshly isolated CD8+ lymphocytes or by CD8+ cell lines, has previously been found to be reduced compared to controls in multiple sclerosis (MS) patients with progressive disease (MS-P). In this study, we found that suppressor activity mediated by CD8+ cell lines, derived from MS patients with stable disease (MS-S) patients and maintained in culture for 14 days, was significantly greater (45 +/- 6%) compared to that mediated by MS-P patients' CD8+ cells (11 +/- 4%, P less than 0.005). The MS-S suppressor values were, however, suggestively reduced compared to controls (60 +/- 6%, P less than 0.05). MNC-mediated suppressor values for the MS-S group (61 +/- 5%) did not differ from the control group (67 +/- 6%). Values for the MS-P group (7 +/- 6%) were significantly reduced compared to MS-S and control groups. Cytotoxic activity mediated by CD8+ cell lines showing defective suppressor function did not differ from control values. The cell lines in MS and control did not differ with respect to their rate of proliferation in the presence of IL-2 and OKT3. Suppressor function in this assay was ablated if exogenous IL-2 was removed from the culture media. These data suggest that defective activated suppressor function is characteristic of the progressive form of MS, although a suppressor defect is also partially expressed in stable MS patients when CD8+ cell lines are studied.

Adult↗
PubMed1988

Nursing assistants' behavior toward the institutionalized elderly.

A study conducted at Grant Park Care Center, an intermediate care nursing facility in Washington, DC, explored nursing assistants' attitudes and behavior toward the institutionalized elderly. Stepwise regression analysis was performed to measure the relationship between nursing assistants' job performance and their attitudes toward their supervisors, in-service training, and the elderly. Study results suggest that education promoting appropriate behavior and positive supervisory role models can significantly affect nursing assistants' behavior toward the elderly.

Aged↗
PubMed1988

Substituted benzamides. 1. Potential nondopaminergic antagonists of chemotherapy-induced nausea and emesis.

A series of new substituted benzamides has been synthesized and evaluated for dopamine antagonist activity and for antagonism of cisplatin-induced emesis in the dog and in the ferret. It was found that modification of the 2-methoxy substituent of metoclopramide was detrimental to dopaminergic D2 antagonism but not necessarily to antagonism of cisplatin-induced emesis. A number of analogues having a beta-keto, beta-hydroxy, beta-methoxy, beta-imino, or beta-unsaturated alkyloxy substituent instead of methoxy have shown equal or superior protection from emesis to that of metoclopramide. At the same time these compounds were found to be free of dopaminergic D2 antagonism in both in vitro ([3H]spiperone binding) and in vivo tests (rat catalepsy, antagonism of apomorphine-induced stereotypy in the rat, and apomorphine-induced emesis in the dog).

Animals↗
PubMed1988

Low dose infusion of atrial natriuretic peptide causes salt and water excretion in normal man.

1. The effects of low dose infusion of atrial natriuretic peptide (ANP) were observed in double-blind, placebo-controlled study in six fluid-loaded volunteers. After baseline observations, hourly increments of 0.4, 2 and 10 pmol min-1 kg-1 were infused with continuous observation of heart rate, blood pressure and cardiac output. Plasma ANP, aldosterone, and catecholamines, and urinary volume and sodium excretion, were estimated at half-hourly intervals. 2. ANP infusion resulted in an increase of 35, 98 and 207% in urinary sodium excretion and of 10, 20 and 71% in urinary volume when compared with placebo. Plasma ANP was markedly elevated above placebo levels only during infusion of 10 pmol of ANP min-1 kg-1. 3. No change in heart rate of blood pressure was noted during the study, but a significant fall in stroke volume index was observed during active treatment. Plasma levels of aldosterone and catecholamines were not significantly different on the 2 treatment days. 4. The potent natriuretic and diuretic effects of this peptide at plasma concentrations not significantly elevated from physiological suggest a hormonal role for ANP in the homoeostasis of salt and water balance.

Adult↗
PubMed1988

Electrical stimulation effects on cutaneous wound healing in rabbits. A follow-up study.

The purpose of this study was to determine the effects of high voltage monophasic pulsed electrical stimulation on wound healing using positive polarity. Forty-four rabbits were assigned to experimental or control groups and followed for four or seven days. We classified the groups as Exp4, Con4, Exp7, and Con7, respectively. Each animal was anesthetized, and a full-thickness incision, 3.5-cm long, was made on its back. After 24 hours, the Exp4 and Exp7 rabbits received high voltage electrical stimulation for two hours twice daily. Wound closure for the Exp4 rabbits (50%) was significantly less than that of the Con4 rabbits (78%). After seven days, however, the Exp7 and Con7 rabbits had similar wound-closure values (80% and 82%, respectively). Tensile-strength values for the control and experimental animals were comparable at both time periods. Histologic examination of the wounds suggested a more rapid rate of epithelization between the Exp4 and Exp7 rabbits compared with the Con4 and Con7 rabbits. The results of this study are inconclusive, but may indicate that positive-polarity stimulation enhanced wound closure between four and seven days of treatment.

Animals↗
PubMed1988

Intrinsic disc pressure as a measure of integrity of the lumbar spine.

Intradiscal pressure and volume measurements were made in 84 fresh cadaveric lumbar spine disc spaces. The nucleus was injected with a roentgenographic contrast agent under fluoroscopic examination. The intrinsic pressure, the pressure at which the agent entered the disc, and the maximum pressure that the disc could hold were measured. The discs were graded for degeneration. The intrinsic and maximum pressures were found to be inversely related to disc degeneration grade, and directly related to each other. Relatively greater degeneration was found at lower levels of the lumbar spine as compared to the upper levels. The intrinsic disc pressure may prove to be a useful clinical tool in the evaluation of spinal integrity.

Biomechanical Phenomena↗
PubMed1988

Interaction of salicylate and corticosteroids in man.

Corticosteroids have been reported to decrease the plasma concentrations of salicylate when salicylates have been administered chronically at high doses. In the present study, two single, oral doses of sodium salicylate, 10 mg kg-1 were administered to six adult subjects with a variety of inflammatory conditions both before and during treatment with daily oral doses of prednisone (12-60 mg). Concomitant prednisone therapy did not increase the whole body clearance of single doses of salicylate in these subjects (0.0275 +/- 0.08 l kg-1 h-1 before prednisone; 0.0247 +/- 0.03 l kg-1 h-1 during prednisone therapy; P greater than 0.05). These results indicate that corticosteroids do not alter the clearance of single doses of salicylate in man.

Adrenal Cortex Hormones↗
PubMed1988

Separation of simian virus 40 large-T-antigen-transforming and origin-binding functions from the ability to block differentiation.

Wild-type simian virus 40 large T antigen is very effective at blocking adipocyte differentiation in 3T3-F442A cells as assayed by triglyceride accumulation, induction of glycerophosphate dehydrogenase activity, and expression of mRNAs for glycerophosphate dehydrogenase, the adipocyte serine protease adipsin, and the putative lipid-binding protein adipocyte P2. Point mutants defective for either origin-specific DNA binding or transformation blocked differentiation as completely as wild type.

Adipose Tissue↗
PubMed1988

CRF activates autonomic nervous system and reduces natural killer cytotoxicity.

Corticotropin-releasing factor (CRF) acts within the brain to elicit changes in neuroendocrine, autonomic, and behavioral activity similar to those observed after stress. A reduction of immune function has also been described following central administration of CRF. In this study, we examined whether autonomic nervous system activation plays a role in CRF-induced suppression of natural killer (NK) cytotoxicity. synthetic rat CRF (1.0 microgram) microinjected into the lateral ventricle significantly increased plasma concentrations of norepinephrine and reduced splenic NK cell activity in the rat. Pretreatment of the animals with the ganglionic-blocking agent chlorisondamine completely abolished the CRF-induced increase in plasma norepinephrine levels and reduction in NK activity. However, CRF-induced elevations in plasma levels of adrenocorticotropic hormone and corticosterone were not affected by chlorisondamine. The results of this study suggest that activation of the sympathetic nervous system plays a role in CRF-induced suppression of NK cytotoxicity.

Adrenocorticotropic Hormone↗
PubMed1988

Peak density and distribution of ganglion cells in the retinae of microchiropteran bats: implications for visual acuity.

We have estimated the total number, distribution and peak density of retinal ganglion cells (RGCs) in retinal wholemounts of several species of microchiropteran (echolocating) bats. The estimates are based on counts of Nissl-stained, presumed RGCs. The total number of presumed RGCs varies among the species: from about 4,500 in Rhinolophus rouxi to about 120,000 in Macroderma gigas. In addition, in two species (Nyctophilus gouldi and M. gigas), the estimates are based on counts of positively identified RGCs retrogradely labelled with the enzyme horseradish peroxidase injected into the retinorecipient nuclei. In these two species, the numbers and distributions of retrogradely labelled RGCs and Nissl-stained presumed RGCs are very similar. In all six species studied, the peak-density regions of presumed (or positively identified) RGCs are located in the inferotemporal retinae, and the RGC isodensity lines tend to be horizontally elongated. However, the RGC densities in the high-density regions are only 2-4 times greater than those in the low-density regions in the superior retinae. The somal sizes of RGCs vary from 5 to 16 micron in diameter and are unimodally distributed. There is no indication of the existence of distinct morphological classes of RGCs. The axial lengths of microchiropteran eyes vary from 1.8 mm in R. rouxi to 7.0 mm in M. gigas. For all species the posterior nodal distance (PND) was assumed to be 0.52 of the axial length of the eye. This assumption is based on the analysis of published data concerning schematic eyes of nocturnal vertebrates. These derived values of the PNDs allowed us to calculate the retinal magnification factors and the number of RGCs per degree of visual angle. From these, the upper limits of visual acuity were derived on the basis of the assumptions of the sampling theorem. The estimated upper limits of visual acuity of the six species of echolocating bats vary from about 0.35 cycles/degree in R. rouxi to about 2 cycles/degree in M. gigas. This range is quite similar to the range of visual acuities in murid rodents.

Animals↗
PubMed1988

Comparison between Gorham's Proverbs Test and the revised Shipley Institute of Living Scale for a black population.

A total of 278 black women (183) and men (95) were administered the Gorham's Proverbs Test and the Shipley Institute of Living Scale (revised). This study compared Abstract scores on the Gorham's Proverbs Test with Vocabulary and Abstract scores on the Shipley Institute of Living Scale. The two tests were remarkably similar in terms of score distributions and susceptibility to the effects of age, perceived socioeconomic level during childhood, education, and perceived quality of education. Analysis also showed that abstract reasoning, as measured by these tests, is not free from the effects of vocabulary skills. Mean scores on both tests were within the range of mean scores previously reported in the literature.

Adolescent↗
PubMed1988

Familiarity with proverbs and performance of a black population on Gorham's Proverbs Test.

The Gorham Proverbs Test was administered to 278 black participants residing in a large metropolitan area in Southern California. Respondents were also asked to indicate whether they were familiar with each of the 40 proverbs in the test. Scores were significantly affected by respondents' ages, education, and perceived childhood socioeconomic status. Familiarity with a proverb increased the probability of its correct interpretation. Familiarity of proverbs and attempts to interpret them were significantly associated, that is, respondents tended not to attempt interpretation of unfamiliar proverbs. The number of familiar proverbs per test was not significantly associated with respondents' test scores. The mean Abstract score obtained in this study was comparable to mean scores previously reported in the literature, suggesting that ethnic differences do not significantly affect performance on the Proverbs Test.

Adolescent↗