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Biomedical subjects

T May

Publications and source records attributed to T May.

At least 127 records · Page 7Linked to original sources
PubMed1993

1-Methyl-4-phenylpyridinium (MPP+) binds with high affinity to a beta-carboline binding site located on monoamine oxidase type A in rat brain.

The in vitro binding of [3H]pargyline and [3H]harman ([3H]1-methyl-beta-carboline) to monoamine oxidase A (MAO-A; EC 1.4.3.4) on membranes of rat cerebral cortex was evaluated. Displacement of the [3H]pargyline binding on MAO-A (L(-)-deprenyl suppressed binding to MAO-B) by harman, 1-methyl-4-phenylpyridinium (MPP+) and 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP) revealed IC50 values of 250 +/- 100 nM, 3.1 +/- 0.8 microM, and 5.1 +/- 0.4 microM, respectively. Displacement of the selective, reversible, high-affinity [3H]harman binding to MAO-A revealed inhibition in a competitive manner with Hill coefficients about unity of each compound tested and calculated apparent Ki-values of 4.7 +/- 2.0 nM, 91 +/- 13 nM and 2.4 +/- 0.8 microM, respectively. The data of [3H]harman displacement support the hypothesis of a high-affinity binding site of the neurotoxin MPP+ located on mitochondrial MAO-A with a significant influence on the development of MPTP induced parkinsonism.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1993

Age-related alteration in signal transduction: involvement of the cAMP cascade.

In the present study, we have investigated the involvement of the cAMP signal transduction pathways in young and aged rats. A significantly higher endogenous adenosine 3':5'-cyclic monophosphate (cAMP) level and a significant decline of the adenylate cyclase [AC, ATP pyrophosphate-lyase (cyclizing), EC.4.6.1.1.] activity were observed in striatal tissue from young rats (3 months) in comparison to aged rats (approximately 40 months). In the nucleus accumbens (NA), no age-dependent changes in the cAMP concentration and in the AC basal activity were found. To address the question, whether the interactions of guanine nucleotide-binding protein (G-protein) subunits (G alpha s and Gi) with AC have changed in the aging process, various pharmacological agents that modulate the AC activity (e.g., beta, tau-imidoguanine 5'-triphosphate (GppNHp), sodium fluoride (NaF), forskolin (FSK), and the combinations of GppNHp plus FSK, NaF plus FSK, and NaF plus ethanol (ETOH)) were applied. In addition, a [3H]FSK binding test was carried out. In striatal and NA tissue, the stimulation of the AC activity by FSK was inhibited by GppNHp (via Gi-protein) and was superadditive by the combination of FSK and NaF (via Gs-protein). The absolute AC activity upon stimulation by all agents used was significantly lower in the aged striatum compared to young striatum. In the NA, however, the AC activity showed an age-dependent reduction only upon FSK and upon FSK plus GppNHp stimulation. There was no difference in the specific [3H]FSK binding to the G alpha s protein-coupled catalytic subunit of the AC between young and aged animals both in the striatum and NA.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗
PubMed1993

[Severe infections caused by methicillin-resistant Staphylococcus aureus. 62 cases].

A French multicentre study was conducted in 15 Infectious Diseases departments; 347 cases of severe staphylococcal infections were collected during one year (October 1989 to October 1990): Two-hundred and fifty-eight strains were analysed with complementary bacteriological studies, including 62 strains of methicillin-resistant Staphylococcus aureus. Epidemiological, clinical and therapeutic aspects were investigated. Nosocomial infection was responsible for 90 percent of the cases, and previous antibiotic therapy was reported in 74 percent. An invasive procedure was incriminated in 43 patients (69 percent); intravenous catheter (38 percent), mechanical ventilation (31 percent), surgery (22 percent), prosthetic device (20 percent). Thirty-nine patients were treated with glycopeptides either alone or in combination with beta-lactams, aminoglycosides, fucidic acid, fosfomycin, rifampicin, quinolones or synergistines, showing the great diversity in the choice of antibiotics in methicillin-resistant S. aureus infections. More than 90 percent of these strains were resistant to gentamicin and quinolones, 80 percent of clindamycin and 70 percent to rifampicin. No resistance to glycopeptides (vancomycin or teicoplanin) was observed. Prognosis was severe, with a mortality rate of 35 percent, justifying educational and prophylactic measures in at risk medical departments.

AIDS-Related Opportunistic Infections↗
PubMed1993

Altered dopamine receptor mediated signal transmission in the striatum of aged rats.

Striatal membranes of very old (40 months) as against young (3 months) female Wistar rats were used. Binding saturation experiments with [3H]SCH 23390 at the dopamine (DA) D1 receptor (D1) and [3H]spiperone at the DA D2 receptor (D2) revealed no change in the affinity (Kd) but a significant decrease in the density (Bmax) of D1 (-31%, P < 0.005) and of D2 (-22%, P < 0.05), respectively, in the aged vs. young striata. Displacement of either [3H]SCH 23390 or [3H]spiperone binding by DA displayed biphasic curves. The Hill coefficient (nH) was significantly increased in the senescent compared with the young of D1 (0.72 +/- 0.04 vs. 0.61 +/- 0.03, P < 0.025) but unchanged of D2 (0.49 +/- 0.04 vs. 0.51 +/- 0.02). The proportion of the high-affinity agonist binding state (Rhigh) was significantly decreased (P < 0.025) in the older (20.9 +/- 3.2%) in comparison with the young (30.6 +/- 2.0%) in D1 but increased non-significantly in D2 (47.9 +/- 2.6 vs. 40.5 +/- 5.1%). Calculating the resulting Bmax from Scatchard and displacement analyses of each single aged and young animal revealed a highly significant reduction (P < 0.001) of the high-affinity agonist binding state of D1 (-53%) as well as a non-significant reduction of D2 (-8%) in the older. Simultaneously, a significant 57% decrease (P < 0.01) in the adenylate cyclase (AC) activity stimulated by 10 microM DA in the senescent compared with the young animals was monitored. The DA stimulation of AC was reversed in both cases by the addition of 200 nM of the D1 antagonist SCH 23390.

Adenylyl Cyclases↗
PubMed1993

Postmortem concentrations of phenobarbital, carbamazepine, and its metabolite carbamazepine-10,11-epoxide in different regions of the brain and in the serum: analysis of autoptic specimens from 51 epileptic patients.

Postmortem concentrations of phenobarbital (PB), carbamazepine (CBZ), and its metabolite carbamazepine-10,11-epoxide (CE) were determined by high-performance liquid chromatography in the serum (total and free) and in specified areas of the brain (frontal, temporal, occipital cortex, and white matter, as well as cerebellum) of 51 deceased epileptic patients. The concentrations of PB and CBZ in the frontal cortex were approximately 1.4 times higher, and of CE were 1.1 times higher than the total concentrations in the serum. Furthermore, the concentrations of PB in the frontal cortex were approximately 2.1 times, of CBZ were 4.5 times, and of CE were 2.1 times higher than the free concentrations in the serum. The distribution of the three substances in the brain is rather homogeneous and seems to follow basic physicochemical principles. This means that the concentrations of the substances in the white matter are, depending on their lipophilicity, modestly but significantly higher than in the cortex. Small and in part statistically significant concentration differences between different regions of the cortex and also of the white matter may be explained by differences in the lipid content of the respective regions and by the lipophilicity of the respective substance. The concentrations in the cerebellar hemisphere (neocerebellum) were nearly identical to those in the frontal cortex. Remarkably increased or decreased concentrations were not observed in any region of the brain.

Adolescent↗
PubMed1993

The nurse under physician authority.

A medical centre is an institution established for a specific purpose: to facilitate the health and health-related welfare of the medical centre's patients. Within this institution, there are a variety of professionals who act and interact to serve this purpose. Of particular interest is the interaction between physician and nurse. Generally, the nurse is thought to be under a certain obligation to implement a physician's orders unless there is good reason not to do so. This qualifier places a conflicting obligation upon the nurse not to implement some physician orders. How should a judgement about which orders there is 'good reason' not to implement be made? I propose to approach this question through an analysis of the obligation the nurse has to implement the order of a physician, and the conditions under which the order does not pose such obligations. This analysis will consist of an examination of the obligation in terms of the purposive authority of the physician. For example, in the context of the medical centre, the physician's medical training qualifies her as best able to make determinations of what treatment would promote the patient's health. However, this purpose not only serves as the basis of the physician's authority, but also serves as a limitation upon the physician's authority (for example, an order which would harm the patient would not reflect the purpose for which the physician has been given authority). Thus, a philosophical investigation into the nature of the obligation to implement a physician's orders can help to clarify those occasions when a nurse should not implement an order.

Ethics, Nursing↗
PubMed1993

Hypertrophic pulmonary osteoarthropathy associated with granulomatous Pneumocystis carinii pneumonia in AIDS.

A case of hypertrophic pulmonary osteoarthropathy (HPOA) in a HIV-infected patient with granulomatous Pneumocystis carinii pneumonia is described. This is the third case of HPOA associated with AIDS reported in the literature. Granulomatous P. carinii pneumonia is an unusual manifestation of P. carinii infection. Surgical treatment of this condition may lead to the dramatic spread of P. carinii causing a fulminant course with fatal outcome.

AIDS-Related Opportunistic Infections↗
PubMed1993

Supplemental protein influences on carbohydrate degradation and bacterial 16S ribosomal ribonucleic acid.

This research examined the mechanism by which soybean protein stimulates growth of mixed ruminal anaerobes and degrades structural polysaccharides in vitro. Soybean meal, isolated soy protein, or branched-chain VFA was added to orchardgrass hay substrate in Experiment 1. Cell-wall degradation increased 14.5% over that of the control by protein addition. Protein addition resulted in 1.3- to 1.5-fold increases in bacterial growth. Hybridization with a 16S probe specific for Fibrobacter succinogenes indicated that protein addition did not influence the proportion of this species. For in vitro Experiment 2, optimal protein for cell-wall degradation was 2 g/L in cultures containing tall fescue hay. To determine whether protein stimulated microbial colonization of plant cell wall (Experiment 3), orchardgrass hay was placed in 14-L fermentors; treatments were control, NH3 N (2 g of N/L), or isolated soy protein (2 g of N/L). Addition of protein and NH3 N increased the extent of cell-wall disappearance 9.7% above control. Protein and ammonia improved cell-wall digestion, but protein had the greatest stimulatory effect on prokaryote growth with no preferential effect of F. succinogenes.

Ammonia↗
PubMed1992

Striatal dopamine D1-like receptors have higher affinity for dopamine in ethanol-treated rats.

Experiments were carried out with brain tissues of ethanol-experienced (long-term ethanol intake but withdrawn) vs. ethanol-naive animals. The in vitro 3H antagonist binding of [3H]SCH 23390 and of [3H]spiperone to striatal dopamine D1- and D2-like receptors revealed no significant changes in KD and Bmax values. Displacement of the 3H antagonist binding by dopamine indicated high- and low-affinity states, which also showed no significant alteration at the D2-like receptor but a 5-fold increase of dopamine affinity at the high-affinity state of the D1-like receptor of the ethanol-experienced rats.

Animals↗
PubMed1992

Peripheral B cells with intracytoplasmic mu chains in HIV infection.

Besides the major alteration of T lymphocytes, B-cell anomalies have been reported in HIV infection, related to late stages of B-cell maturation, and considered to result from the dysregulation of T/B interactions. Because T cells are also involved in the control of lymphopoiesis and/or because of specific alterations of the B lineage, anomalies of B-cell maturation could occur in HIV-infected patients. We investigated the presence of immature pre-B lymphocytes, characterized by cytoplasmic mu chains, in 35 peripheral blood samples from healthy controls, 82 from HIV-positive/non-AIDS patients, and 45 from AIDS patients. Significant numbers of such cells were observed in 48% of HIV-seropositive patients and in 40% of the patients with AIDS disease. The presence of pre-B cells correlated with higher numbers of CD8+ and/or CD57+ cells and of peripheral lymphocytes. These data suggest that B-cell dysregulation in HIV infection may lead to the abnormal release of immature B cells in the peripheral blood. This observation may be interpreted as a sign of bone marrow activity.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Central actions of neuropeptide-Y may provide a neuromodulatory link between nutrition and reproduction.

Central injection of neuropeptide-Y (NPY) has been shown to attenuate secretion of LH in ovariectomized rats, rabbits, and monkeys. Several investigators have reported elevated concentrations of NPY in the central nervous system of undernourished animals. The relationship between nutrition and reproduction positions NPY as a potential neuromodulator involved in nutritionally induced changes in secretion of LH. Three experiments were conducted with the following objectives: 1) to examine the effects of NPY on secretion of LH in ovariectomized (OVX) ewes and the influence of estradiol-17 beta (E) on these effects; 2) to determine whether NPY may act through direct effects on the pituitary to influence secretion of LH; and 3) to determine changes in concentrations of NPY in laterocerebro-spinal fluid (CSF) of food-restricted ewes compared to well-fed ewes. In Experiment 1, OVX ewes with s.c. implants of E (OVX + E, n = 4) or no steroid treatment (OVX, n = 4) were fitted with intracerebroventricular (i.c.v.) and jugular cannulae. One of 4 doses of porcine NPY (pNPY; 0, 0.5, 5, or 50 micrograms) was injected i.c.v. and blood samples were collected every 10 min for 4 h prior to and following i.c.v. injection. Blood serum was assayed for LH. The experiment was replicated four times such that each ewe received each dose of pNPY. Mean concentrations of LH as well as frequency and amplitude of pulses of LH were attenuated in response to i.c.v. injection of pNPY in a dose-related manner in both OVX and OVX + E ewes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Nutritional Physiological Phenomena↗
PubMed1992

Postmortem concentrations of phenytoin in different regions of the brain and in the serum: analysis of autoptic specimens from 24 epileptic patients.

Postmortem concentrations of phenytoin (PHT) were determined by high-performance liquid chromatography in the serum (total and free) and in specified areas of the brain (frontal, temporal, occipital cortex and white matter, as well as cerebellum) of 18 epileptic patients who died following chronic diseases (group A) and of six otherwise healthy epileptic patients who died suddenly and unexpectedly (group B). The free concentrations in the serum correlated considerably better (r = 0.987) than the total concentrations in the serum (r = 0.871) with the concentrations in the frontal cortex. The concentrations in the frontal cortex were about nine times that of the free serum concentrations. The data show that the PHT concentrations in the frontal, temporal and occipital cortex largely agree. The concentrations in the white matter were significantly higher (frontal region 54%, temporal region 30%, occipital region 36%) than in the cortex. The concentrations in the cerebellar hemisphere (neocerebellum) were nearly identical with those in the frontal cortex. Regression analysis showed that on comparable total serum concentration the patients of group A had significantly higher free serum concentrations and significantly higher concentrations in the frontal cortex than the patients of group B. In respect of the concentration ratios cortex to serum free and in regard of the local distribution of PHT in the brain no difference, however, was found between those patients who died from chronic diseases and those who died suddenly.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Use of DNA probes to monitor nutritional effects on ruminal prokaryotes and Fibrobacter succinogenes S85.

We used DNA probes to study dietary effects on the prokaryotic population in the rumen. Procedures used to isolate and quantify prokaryotic 16S ribosomal RNA (rRNA) from the rumen using universal and species-specific DNA probes were evaluated. In this experiment, three ruminally fistulated steers were fed orchard-grass hay, and ruminal digesta were collected at 0, 3, and 9 h after offering hay (0800). Samples of ruminal digesta were taken from the interior portion of the digesta mat and from the fluid below the mat in the dorsal rumen. Freezing (-65 degrees C) and blending samples both increased (P less than .07) the yield of 16S rRNA from ruminal digesta. Extraction of prokaryotic rRNA was greater (P less than .04) when phenol buffered with sodium acetate was used than when it was buffered with hydroxymethyl-amino-methane. Prokaryotic 16S rRNA concentration of the fluid phase was similar (P greater than .10) at 0, 3, and 9 h after offering hay. Prokaryotic 16S rRNA concentration of the mat phase increased up to the 9 h after feeding. The proportion of Fibrobacter succinogenes remained constant in both digesta phases at all times measured. From these data we concluded that DNA probes can be used to monitor bacterial population shifts in the rumen.

Animals↗
PubMed1992

Expression of the T-cell receptor in HIV infection.

Expression of the T-cell receptor (TCR) was investigated on peripheral lymphocytes in 270 samples from HIV+ patients at different stages of infection. TCR is composed either of an alpha and a beta chain, or, in a smaller subset of T-cells, of a gamma and a delta chain, closely associated with CD3. The numbers and percentages of positive cells were established using monoclonals to the alpha and delta chains of TCR. The values of alpha-TCR positive cells were constantly lower than those observed for CD3, with a mean of 53% (+/- 19%) versus 66% (+/- 17) respectively for asymptomatic patients or patients with persistent generalized lymphadenopathy, and of 36% (+/- 19) versus 46% (+/- 21) for patients with AIDS disease. There was no compensatory increase in the number of cells expressing delta-TCR. These data demonstrate a new alteration of the immune system in HIV infection, which appears to occur early in this disease.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Steady state concentrations and diurnal fluctuations of carbamazepine in patients after different slow release formulations.

The bioavailability and serum level fluctuations of three carbamazepine (CBZ, CAS 298-46-4) slow release preparations marketed in Germany were compared in patients with epilepsy. Ten patients who were on CBZ monotherapy and had reached a steady state with morning trough levels above 10 micrograms/ml received all 3 preparations in sequential 3-day periods. On the 3rd day of each period, a 24-h serum drug level profile was determined. Only minimal differences could be found. One preparation had a significantly higher AUC than one of the others (p less than 0.05), and this difference seemed to be correlated with higher fluctuations of serum levels and, especially, an increased Cmax. Although the group differences are minimal, more important differences could be observed individually. One patient had, with one of the three preparations, a reduction in seizure frequency but simultaneously developed important signs and symptoms of toxicity. It is concluded that all 3 preparations are equally suitable for chronic antiepileptic drug treatment. In a well-controlled patient, however, interchange between preparations is not advisable as their kinetics in individual patients can be sufficiently different to cause toxicity or seizure relapse.

Adolescent↗
PubMed1992

[Anal and perianal lesions in symptomatic HIV infections. Prospective study of a series of 190 patients].

The aim of this study was to determine the prevalence and type of symptomatic anal and perianal diseases in patients belonging to group IV of the Centers for Disease Control classification of infections with human immuno-deficiency virus. Among the 190 prospectively included patients, 31 (16.3 percent) (30 men, 29 homosexuals or bisexuals; 1 woman) had anal symptoms and were referred for proctological examination. Thirty-five "specific" diagnoses were reached in 25 (13.2 percent) patients: 21 ulcerations, 7 condyloma acuminata, 6 perianal sepsis and 1 non-Hodgkin malignant lymphoma. The causes of ulcerations were 16 herpes, one syphilitic chancre and one fissure-in-ano. Three ulcerations remained unexplained despite bacteriological, viral, and histological investigations. Eight patients underwent 10 surgical procedures without significantly delayed wound healing.

Acquired Immunodeficiency Syndrome↗