The binding of cyanide and carbon monoxide to bacterial cytochrome bo.
Explore the source record for details and available documents.
Carbon Monoxide↗
Biomedical subjects
R Mitchell
Publications and source records attributed to R Mitchell.
The influence of the New Pathway curriculum on Harvard medical students.
BACKGROUND: This study evaluated the effect of a radically redesigned curriculum at Harvard Medical School on preclinical students' knowledge, skills, personal characteristics, approaches to learning, and educational experiences. METHOD: Multiple measures were used to collect data from 121 students from the entering classes of 1989 and 1990 who had been randomly assigned to the New Pathway or traditional curricula; all had applied to be in the new curriculum. RESULTS: The New Pathway students reported that they learned in a more reflective manner and memorized less than their control counterparts in the traditional curriculum during the preclinical years. The New Pathway group preferred active learning and demonstrated greater psychosocial knowledge, better relational skills, and more humanistic attitudes. They felt more challenged, had closer relationships with faculty, and were somewhat more anxious than those in the traditional program. There was no difference in problem-solving skills or biomedical knowledge base. CONCLUSION: Students in the new curriculum learned differently, acquired distinctive knowledge, skills, and attitudes, and underwent a more satisfying and challenging preclinical medical school experience without loss of biomedical competence. These findings should encourage other schools to consider such a curriculum.
Clinical Competence↗
Less acidic forms of luteinizing hormone are associated with lower testosterone secretion in men on haemodialysis treatment.
OBJECTIVE: Men with chronic renal failure treated by haemodialysis have raised levels of bioactive LH (B-LH) and immunoreactive LH (I-LH) but reduced B-LH:I-LH (B:I) ratio and testosterone (T) secretion. This study investigated the LH isoform distribution in serum from normal adult males and males on regular haemodialysis treatment. DESIGN: Four blood samples (2 ml) were obtained at 15-minute intervals from a group of men on regular haemodialysis treatment. These samples were part of a larger pulse profile series and showed no evidence of LH pulsatility. The serum was pooled for each individual patient. Blood (10 ml) was also drawn randomly from healthy male volunteers. The sera were chromatofocused on a 4-ml mono-P column attached to a fast performance liquid chromatography system. This procedure separates the LH isoforms according to their isoelectric point. The pH gradient was between pH 7 and pH 4. PATIENTS: The five men with chronic renal failure were aged between 18 and 40 years and had been on haemodialysis for a mean of 10 months (5-20). They were sampled the night prior to a dialysis session. The five normal healthy volunteers had never had any endocrine disorder diagnosed. MEASUREMENTS: An immunoradiometric assay and a commercially available (Delfia) immunofluorimetric assay were employed for detection of LH in the sera and in chromatofocusing fractions. B-LH and testosterone were also measured in the sera. RESULTS: Hormone data (mean +/- SEM for normal and renal subjects respectively) were 15.5 IU/l +/- 1.2 and 26.9 +/- 7.2 (B-LH), 6.0 IU/l +/- 0.3 and 16.5 +/- 4.8 (irmaLH), 5.7 +/- 0.5 and 13.6 +/- 4.8 (fluorLH), 25.2nmol/l +/- 2.0 and 12.1 +/- 1.2 (T). The serum B:I ratios were 2.6 +/- 0.1 and 2.6 +/- 0.2 (controls, irmaLH and fluorLH respectively) and 1.7 +/- 0.1 and 2.1 +/- 0.1 (chronic renal failure group). Recovery of LH from the column was 111 +/- 12% (mean +/- SEM) by IRMA and 104 +/- 7% by IFMA for the ten FPLC runs. The median pI for the LH distribution measured by both assays was in the region 6.54-6.40 for subjects with chronic renal failure and 6.09-5.95 for controls. Median pI was negatively correlated to the B-LH:irmaLH (P < 0.0001) and B-LH:fluorLH ratios (P = 0.002) in the serum. Furthermore, the proportion of isoforms recovered in the pH region 6.25-5.50 increased with increasing T levels in the serum (P < 0.004). CONCLUSION: The distribution of LH in serum of men on haemodialysis is more basic than in normal men. The greater the proportion of more acidic LH species, particularly those with a pI of between 5.50-6.25, the higher the ratio of LH bioactivity to immunoactivity and consequently testosterone levels.
Adolescent↗
Guidelines for administration of blood products: transfusion of infants and neonates. British Committee for Standards in Haematology Blood Transfusion Task Force.
Explore the source record for details and available documents.
Adult↗
Monoclonal antibodies to high-incidence Kell epitopes: characterization and application in automated screening of donor samples.
Monoclonal antibodies, LM313/706 and LM357/828, recognize high-frequency epitopes which are absent on red cells of Ko phenotype. Both antibodies have proved suitable for automated screening of blood donor samples, with 5 ml of each culture supernatant sufficient to screen 3,000 donor samples. In a screen of 45,545 samples, LM313/706 revealed 11 samples (1:3686) of Kp(a+b-) phenotype. Thirty-seven samples of K+k- phenotype were identified in 15,235 samples screened with LM357/828 antibody (0.24%). The epitope recognized by LM313/706 was inactivated by 2 mM DTT suggesting a possible association with the Jsa/Jsb antigen structure. The expression of the k-like epitope detected by LM357/828 antibody was found to be influenced by pH change.
Antibodies, Monoclonal↗
The low risk of hepatitis C virus transmission among sexual partners of confirmed HCV-positive blood donors.
Explore the source record for details and available documents.
Blood Donors↗
Anti-D (again!)--tell me the old, old story...
Explore the source record for details and available documents.
Erythroblastosis, Fetal↗
The average daily energy expenditure of elderly males and females.
The aim of this study was to report on the average daily energy expenditure by elderly males and females in their normal day-to-day activities. The study was based on an analysis of data collected over six months from daily diary recording of activities. The subjects, 82 males and 93 females, were non-institutionalized volunteers with a mean age of 68 years. A multivariate analysis of variance indicated that there were no differences between males and females in total mean daily energy expended on Sporting activities. Females expended twice as much energy as males on Household Chores (F = 36.3,p < 0.001). Males expended over three times as much energy as females on gardening (F = 56.7, p < 0.001) and over seven times as much on Maintenance (F = 53.6, p < 0.001). There were also differences between males and females on energy expended while Walking (F = 6.1, p < 0.02) and on Miscellaneous activities (F = 6.3, p<0.05). It is concluded that sex stereotypical roles for activities required at younger ages are continued into old age. The implications of these findings for prescribing regular exercise in the elderly are discussed, indicating specific activities that might prove to be beneficial.
Aged↗
Activation of MAP kinase associated with the priming effect of LHRH.
A MAP kinase activity assay was developed to determine whether the LHRH receptor could activate this enzyme (particularly during LHRH priming). In anterior pituitary tissue from prooestrous rats LHRH caused concentration-dependent activation of MAP kinase after 5-10 min and continued for up to 60 min of incubation. The magnitude of this response correlated with that of LHRH priming on various days of the oestrous cycle but not with the magnitude of 1st hour (unprimed) LHRH-induced LH release. The response to LHRH was mimicked by a phorbol ester but not by ionomycin and was blocked with high potency by GF 109203X but not by H7 (in a similar manner to the PKC species that mediates LHRH priming). Neither the tyrosine kinase inhibitor lavendustin A nor the protein synthesis inhibitor cycloheximide blocked LHRH-induced MAP kinase activation. The possible functional significance of MAP kinase activation in gonadotrophs is considered with respect to LHRH priming.
Animals↗
Evidence for a role of phospholipase A2 in the mechanism of LHRH priming in rat anterior pituitary tissue.
The phospholipase A2 (PLA2) inhibitors, quinacrine, p-bromophenacyl bromide, ONO-RS-082, aristolochic acid and chloracysine blocked the priming effect of LHRH, but not acute LHRH-induced gonadotrophin release measured in anterior pituitary pieces in pro-oestrous rats in vitro. These results suggest that the intracellular mechanisms underlying LHRH priming are distinct from those which mediate LH release in the present circumstances in that they involve PLA2. Furthermore, neither LHRH-induced LH release from preprimed tissue nor Ca(2+)-induced LH release were attenuated by quinacrine, indicating that this inhibitor does not interfere with the general Ca(2+)-dependent secretory apparatus of the gonadotroph and that the critical period for its action is in the induction of priming. LHRH induced the release of [3H]arachidonic acid ([3H]AA) from [3H]AA-prelabelled anterior pituitary tissue from pro-oestrous rats; a response which was sensitive to inhibitors of PLA2, of protein kinase C (PKC) and of protein synthesis. Activation of PKC also resulted in [3H]AA release which was inhibited with exactly the same pharmacological profile as the response to LHRH. Both gonadotrophin secretion and [3H]AA release responses to LHRH and to phorbol ester varied in parallel during the oestrous cycle and in ovariectomized/oestradiol-17 beta-replaced animals, as did their sensitivity to quinacrine and the protein synthesis inhibitor cycloheximide. These results indicate that LHRH priming is dependent on a hormonally regulated cascade involving a distinct form of PKC acting through a protein synthesis-dependent step to release AA by means of PLA2 activity. The priming effect was mimicked (at least in part) by conditioning preincubation with AA, confirming the functional relevance of this signalling cascade. Results using standard inhibitors of lipoxygenase/epoxygenase pathways were equivocal as to whether these pathways were critically involved, whilst cyclo-oxygenase inhibitors were completely without effect. The steps downstream from AA (and its possible metabolites) by which stimulus-secretion coupling is up-regulated in priming remain to be clarified.
Acetophenones↗
Characterization of a new thermophilic sulfate-reducing bacterium Thermodesulfovibrio yellowstonii, gen. nov. and sp. nov.: its phylogenetic relationship to Thermodesulfobacterium commune and their origins deep within the bacterial domain.
A thermophilic sulfate-reducing vibrio isolated from thermal vent water in Yellowstone Lake, Wyoming, USA is described. The gram-negative, curved rod-shaped cells averaged 0.3 micrometer wide and 1.5 micrometers long. They were motile by means of a single polar flagellum. Growth was observed between 40 degrees and 70 degrees C with optimal growth at 65 degrees C. Cultures remained viable for one year at 27 degrees C although spore-formation was not observed. Sulfate, thiosulfate and sulfite were used as electron acceptors. Sulfur, fumarate and nitrate were not reduced. In the presence of sulfate, growth was observed only with lactate, pyruvate, hydrogen plus acetate, or formate plus acetate. Pyruvate was the only compound observed to support fermentative growth. Pyruvate and lactate were oxidized to acetate. Desulfofuscidin and c-type cytochromes were present. The G + C content was 29.5 mol%. The divergence in the 16 S ribosomal RNA sequences between the new isolate and Thermodesulfobacterium commune suggests that these two thermophilic sulfate-reducing bacteria represent different genera. These two bacteria depict a lineage that branches deeply within the Bacteria domain and which is clearly distinct from previously defined phylogenetic lines of sulfate-reducing bacteria. Strain YP87 is described as the type strain of the new genus and species Thermodesulfovibrio yellowstonii.
Fresh Water↗
H7-resistant protein kinase C substrates in two-dimensional gels of proestrous rat anterior pituitary gland.
The presence of Ca(2+)-dependent and -independent protein kinase C (PKC) activities which were stimulated by phorbol-12,13-dibutyrate (PDBu) and sensitive to the kinase inhibitor staurosporine (IC50 values approx. 100 nM) was demonstrated in proestrous rat anterior pituitary gland. These PDBu-induced activities were completely abolished by the PKC-specific inhibitors Ro31-8220 and GF109203X (3 microM). The Ca(2+)-independent activity was more resistant (IC50 = 61 microM) to the kinase inhibitor H7 than the Ca(2+)-dependent activity (IC50 approx. 20 microM), however, this (unusual) resistance to H7 was not observed in the brain regions, hypothalamus and hippocampus. Possible substrates for the Ca(2+)-independent PKC in anterior pituitary were identified by two-dimensional gel electrophoresis and autoradiography following incubation in vitro with [32P]phosphate and 300 nM PDBu +/- 300 nM staurosporine or 30 microM H7. The phosphorylation of six proteins (16, 16, 25, 36, 65 and 69 kDa) was found to be stimulated by PDBu and inhibited by staurosporine, but not H7, in whole tissue, and another two such phosphorylated proteins (each 76 kDa) were observed in microsomal subcellular fractions. These phosphoproteins may be substrates for an H7-resistant PKC isoform previously shown to mediate a number of cellular responses in rat anterior pituitary gland.
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
Characterization of the genes controlling the biosynthesis of the polyketide phytotoxin coronatine including conjugation between coronafacic and coronamic acid.
Pseudomonas syringae pv. glycinea PG4180 produces a chlorosis-inducing phytotoxin, coronatine (COR), which consists of a polyketide component, coronafacic acid (CFA), which is coupled via amide bond formation to coronamic acid (CMA), an ethylcyelopropyl amino acid (aa) derived from isoleucine. P. syringae pv. syringae strains PS51 and PS61, which do not synthesize coronafacoyl compounds (conjugates between CFA and aa), acquired the ability to produce CFA and COR when transformed with p4180A, a 90-kb indigenous plasmid in PG4180. Tn5 mutagenesis indicated that the COR biosynthetic genes in PG4180 are clustered within a 30-kb region on p4180A. The phenotype of selected COR-defective mutants was determined by supplying them with CFA and CMA and by complementation studies with cloned DNA from the COR biosynthetic cluster. Using this approach, the regions encoding CFA and CMA synthesis and coupling activity were localized to the 24-, 12.5- and 2.3-kb regions of the cluster, respectively. Mutants in a 6-kb region required the addition of both CFA and CMA for COR synthesis, which may indicate a regulatory role for this part of the cluster. PS51 and PS61 transconjugants containing cloned DNA from the coupling region produced COR when supplied with CFA and CMA, indicating that coupling activity was cloned and expressed in bacteria lacking the COR biosynthetic cluster.
Amino Acids↗
Characterisation of protein kinase C isoforms and enzymic activity from the alpha T3-1 gonadotroph-derived cell line.
Western blots of alpha T3-1 cell extracts were immunostained with antibodies specific for various protein kinase C (PKC) isoforms. These revealed the presence of PKC types alpha, epsilon and zeta, but beta, gamma, delta and eta were not detected. The potency with which partially-purified cytosolic PKC from alpha T3-1 cells was activated by phorbol 12,13-dibutyrate (PDBu), mezerein and 1,2-dioctanoyl-sn-glycerol was assessed in the presence and absence of Ca2+. The inhibitors staurosporine, K252a, H7, GF109203X and Ro 31-8220 were tested on basal activity, PDBu-induced activity and Ca(2+) + PDBu-induced kinase activity. Each inhibitor showed distinct differences in their IC50 values under the three conditions, suggesting that these inhibitors may exhibit different potencies on the PKC isoforms present in alpha T3-1 cells. Although histone IIIs was used as the phosphate acceptor for most of these experiments, the efficiency of alpha, epsilon and zeta peptide and GS peptide substrates were also determined, with epsilon peptide giving the greatest activity in the presence of PDBu or Ca2+. Each substrate displayed a different pattern of activation under the conditions tested. Overall, the findings suggest that 3 or more PKC isoforms with varying specificities are present in gonadotroph-derived alpha T3-1 cells and that the contribution of each isoform should be considered when these cells are used in models of anterior pituitary cell function where PKC is involved.
Amino Acid Sequence↗
Evidence for a role of tachykinin NK2 receptors in mediating brief nociceptive inputs to rat dorsal horn (laminae III-V) neurons.
Since the NK2 receptor-selective tachykinin, neurokinin A is present in fine primary afferent neurons in addition to the NK1 receptor-selective tachykinin, substance P, we have addressed the relative role of NK1 and NK2 receptors in somatosensory processing in spinal dorsal horn. Recording extracellularly from rat laminae III-V neurons whilst ionophoresing drugs nearby, the selective NK1 receptor antagonists L 688,169, GR 82334 and [D-Pro4,D-Trp7,910Phe11]substance P-(4-11) failed to influence neuronal responses to cutaneous pinch or noxious heat but often enhanced responses to innocuous brush. In contrast, the highly selective NK2 receptor antagonist L 659,874 profoundly inhibited responses to noxious heat but not pinch or brush. Highly selective synthetic agonists for both NK1 and NK2 receptors ([N-acetyl-Arg6,Sar9,Met(O2)11]substance P-(6-11) and GR 64349, respectively) and also NKA showed the inverse effects on sensory responses to those brought about by their antagonists. At higher ionophoretic currents, both NK1 and NK2 receptor agonists increased spontaneous activity. This increased basal firing induced by GR 64349 and neurokinin A (but not that due to [N-acetyl-Arg6,Sar9,Met(O2)11]substance P-(6-11) appeared to partially pre-empt further excitatory responses to noxious heat. It is concluded that although both NK1 and NK2 receptors can clearly mediate excitation of dorsal horn neurons, it is not NK1, but rather NK2 receptors that are important as the physiological transducer of brief thermal nociceptive inputs in this model.
Animals↗
Evidence for a distinct H7-resistant form of protein kinase C in rat anterior pituitary gland.
Inhibition of phorbol 12,13-dibutyrate-induced protein kinase C (PKC) activity from rat midbrain, anterior pituitary and a number of other tissues, as well as COS 7 cells, was studied in vitro. In anterior pituitary, Ca(2+)-independent activity was notably resistant to H7 but sensitive to staurosporine and Ro 31-8220. All Ca(2+)-dependent activity was sensitive to these three inhibitors. Mezerein and 1,2-dioctanoyl-sn-glycerol also activated this H7-insensitive PKC from anterior pituitary. The distribution of this activity, prominently expressed in pituitary and perhaps also lung, and its characteristic resistance to H7 but not other inhibitors, does not obviously correlate with that of any of the well-characterised PKCs, and may reflect either a novel or a modified isoform.
1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
Protein C activity in healthy volunteers--influence of age, sex, smoking and oral contraceptives.
Interpretation of protein C (PC) levels in a given individual has several limitations. A normal PC activity does not necessarily exclude a genetic deficiency nor can a reduced level confirm it. Measuring PC amidolytic activity in 9,648 healthy blood donors has allowed identification of demographic factors which cause variation in PC activity and further hinder interpretation. PC activity displays a log normal distribution and significant variation with age. This is most marked in young adult males when mean PC activity rises from 0.86 iu/ml (15-19 years) to 1.04 iu/ml (45-49 years; P < 0.0001). Pre-menopausal females, who for most age ranges, have mean PC activity below their male contemporaries, show a less marked rise with age until the menopause when PC activity rises further. The use of hormonal contraceptive preparations is associated with an increase in mean PC activity of 0.05-0.08 iu/ml while smoking habit has no influence on PC activity. In view of these findings we strongly recommend the use of age and sex restricted reference ranges when interpreting PC activity.
Adolescent↗
Evidence that protein kinase C alpha has reduced affinity towards 1,2-dioctanoyl-sn-glycerol: the effects of lipid activators on phorbol ester binding and kinase activity.
The effect of 1,2-diacylglycerols on specific binding of [3H]phorbol 12,13-dibutyrate to cytosolic protein kinase C (PKC) was investigated in tissues reported to contain different proportions of PKC isoforms. In lung, frontal cerebral cortex and cerebellum cytosols (enriched in PKC alpha, beta and gamma, respectively) displacement of specific binding by phorbol 12,13-dibutyrate or diacylglycerols containing unsaturated acyl chains was of similar potency for each tissue. A range of 1,2-diacylglycerols containing saturated acyl chains exhibited varying affinities for [3H]phorbol 12,13-dibutyrate binding sites in each tissue; defining an optimal acyl chain length of around 14 carbons in each case. However, the affinities of saturated diglycerides were consistently lower in lung cytosol than in frontal cerebral cortex and cerebellum cytosols, with the greatest differences occurring at lower acyl chain lengths, especially with 1,2-dioctanoyl-sn-glycerol. Furthermore, a mixed micelle assay of PKC activity showed that 1,2-dioctanoyl-sn-glycerol displayed reduced potency at PKC alpha partially-purified from COS 7 cell cytosol compared to the mixture of PKC isoforms present in rat midbrain cytosol. Both low potency of 1,2-dioctanoyl-sn-glycerol as a displacer of [3H]phorbol 12,13 dibutyrate binding and the ability of arachidonic acid to act as an allosteric enhancer of binding, correlated with the proportional PKC alpha content of a range of tissues reported in the literature. In PKC enzyme activity assays, 1,2-dioctanoyl-sn-glycerol, but not phorbol 12,13-dibutyrate, was correspondingly a much poorer activator of PKC alpha from COS 7 cells than of the broad consensus of isoforms in rat midbrain. When alpha and beta isoforms were extensively-purified on DEAE-cellulose then hydroxyapatite, both the low affinity of 1,2-dioctanoyl-sn-glycerol for [3H]phorbol 12,13-dibutyrate binding sites and their allosteric regulation by arachidonic acid were confirmed to be characteristic of the alpha rather than the beta isoforms.
Amino Acid Sequence↗