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Biomedical subjects

M Brown

Publications and source records attributed to M Brown.

At least 595 records · Page 33Linked to original sources
PubMed1987

Ethics.

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Ethics, Dental↗
PubMed1987

Conscious sedation.

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Anesthesia, Dental↗
PubMed1987

The effect of regional retinal photocoagulation on vitreal oxygen tension.

PO2 measurements have been made for the first time within the retina and vitreous of cat eyes to compare normal and photocoagulated areas. This was done to test the hypothesis that the observed beneficial effects of pan-retinal photocoagulation therapy in the treatment of retinal vascular diseases with an ischemic origin, may be due to more oxygen becoming available to the remaining functioning retina. A xenon arc photocoagulator was used to photocoagulate large areas of cat retinas served by one major set of vessels while leaving the remaining retina untouched. After 6 months an acute experiment was performed in which retinal and vitreal oxygen tension profiles were measured using oxygen-sensitive microelectrodes to compare PO2 profiles in normal and photocoagulated regions, for two ventilation conditions: air and 100% O2. The only differences in PO2 values were found for the 100% O2 breathing condition, where values within the retina and in the overlying vitreous were larger in photocoagulated areas. It is proposed that any differences in PO2 distribution which occur for air breathing are masked by the autoregulatory capacity of the retinal circulation and the PO2 buffering capacity of hemoglobin.

Animals↗
PubMed1987

An examination of preconception health teaching by nurse practitioners.

Fifteen nurse practitioners in a Midwestern urban area in the United States of America volunteered to participated in a study which sought to determine what preconception self-care practices are taught to female clients at risk for pregnancy as a part of routine health maintenance. Subjects' teaching responses were compared to an investigator-developed model for preconception counselling. The subjects listened to an audiotape of a stimulus client-nurse practitioner interview. Their responses were audiotaped and categorized into the following categories: nutrition, vitamins, preconception weight, menstrual cycle review, alcohol, smoking, drug use, exercise, environment hazards, dental care, immunizations, and 'other'. Frequency counts of the teaching responses and a X2 analysis comparing teaching responses to expected teaching based on the PREPARED model (X2 = 78.01, P = 0.001) demonstrated a lack of teaching overall. The conclusion was reached that obstetrical care has not expanded into preconception counselling.

Female↗
PubMed1986

Corticotropin releasing factor: central nervous system sites of action.

Corticotropin-releasing factor (CRF) has been microinjected into different brain areas in an effort to characterize specific sites of action of this peptide to influence the concentrations of norepinephrine in plasma. Although many brain sites were identified to be unresponsive to CRF stimulation there were also an abundant number of sites found where CRF elicited significant elevations of plasma catecholamine concentrations. None of the tissue sites of action of CRF were associated with increases of plasma levels of norepinephrine greater than those following CRF administration into the third ventricle. The results suggest that anatomic redundancy exists for the response to exogenous CRF administration.

Animals↗
PubMed1986

Opacity genes in Neisseria gonorrhoeae: control of phase and antigenic variation.

The chromosome of N. gonorrhoeae contains several complete expression genes coding for variant opacity proteins. DNA sequence analysis of two opacity genes derived from the same locus (opaE1) of two isogenic gonococcal variants reveals common and variable regions in these genes. Genomic blotting experiments using synthetic probes suggest gene conversion as a principle for the assembly of variant sequence information in opacity genes. The 5' region of opacity genes is composed of identical pentameric pyrimidine units (CTCTT) encoding the hydrophobic portion of the opacity leader peptide. This coding repeat is variable in a given locus with respect of the number of pentameric units. While all expression loci in a single cell are constitutively transcribed, the production of opacity proteins is determined by the coding repeat sequence on the translational level.

Amino Acid Sequence↗
PubMed1986

Regulation of B-lymphocyte activation, proliferation, and immunoglobulin secretion.

Lymphocyte growth and differentiation are controlled by signals resulting from the interaction of antigen and cellular products, such as lymphokines, with specific cell membrane receptors. Resting B lymphocytes can be activated by low concentrations (1-5 micrograms/ml) of antibodies to membrane IgM, which is the B-lymphocyte receptor for antigen. The binding of anti-IgM to B cells causes a rapid increase in intracellular free calcium concentration ([Ca2+]i), in inositol phosphate concentration, and in protein kinase activity. Moreover, the effects of anti-IgM on B cells are mimicked by the combined use of calcium ionophores and phorbol esters. Since phorbol esters activate protein kinase c, this suggests that the increase in [Ca2+]i and in phosphatidylinositol metabolism stimulated by anti-IgM are critical events in B-cell activation. The entry into S phase of B cells stimulated with anti-IgM depends on the action of a T-cell-derived factor designated B-cell stimulatory factor (BSF)-1. This is a 20,000-Da protein which is a powerful inducer of class II major histocompatibility complex molecules. Although an important cofactor for B-cell proliferative responses to anti-IgM, its major locus of action is on resting B cells. B cells stimulated with anti-IgM and BSF-1 do not synthesize secretory IgM. However, if two additional T-cell-derived factors, B151-TRF and interleukin-2, are added to cultures, a substantial proportion of stimulated B cells produce secretory IgM. BSF-1 has also been shown to participate in the "switch" in Ig class expression. Resting B cells cultured with lipopolysaccharide will switch to IgG1 secretion in the presence of purified BSF-1.

Animals↗
PubMed1986

Immunologic memory to phosphorylcholine (PC). VIII. Expression of the VH-12 gene product in the response to PC-keyhole limpet hemocyanin.

Three murine anti-phosphorylcholine (PC) hybridomas with group II-like fine specificity patterns isolated during a memory response to PC-keyhole limpet hemocyanin (KLH) are examined at the molecular level to determine the origins of the VH and VL used by these antibodies. Southern blots of Hind III cut DNA were hybridized with a probe specific for the V1 gene of the T15 VH family. The V1 germ-line configuration is retained in these hybridomas indicating that this gene which encodes the VH gene product expressed by most group I anti-PC hybridomas is not used for antibody production. Southern blots of Eco RI cut DNA hybridized to a probe specific for JH1-JH4 indicated that all three hybridomas PCG1-2, PCG1-3 and PCM-23 share a 5.2-kb rearranged JH band, suggesting utilization of a common VH gene segment. N-terminal amino acid sequence analysis of the heavy chains of two of the hybridoma proteins PCG1-2 and PCG1-3 indicates that they belong to mouse heavy chain subgroup II and are closest in sequence to a VH-12 isotype anti-PC hybridoma protein, HPC-104, derived from BALB/c mice suppressed for the T15 idiotype; PCG1-2 and PCG1-3 each differed from HPC-104 at only 1/20 residues. In addition, these proteins have in common a lysine at position 1 which has not been found previously in 203 other heavy chain sequences reported. N-terminal sequences of the light chains of PCG1-2 and PCG1-3 are each shown to differ at only 1/22 residues from V kappa 24, and PCM-23 had previously been shown to use V kappa 8; both of these have been associated previously with heavy chains derived from the V1 gene in anti-PC antibodies. These results indicate that the VH-12 isotype can be used during a normal antibody response to PC and thus that heavy chains derived from both subgroup II and subgroup III (the T15 heavy chain) contribute to the molecular heterogeneity observed in memory responses to PC-KLH.

Amino Acid Sequence↗
PubMed1986

Sinus histiocytes in axillary lymph nodes from patients with breast cancer: macrophage characteristics and activation level.

Cell suspensions from 16 tumour-free axillary lymph nodes from breast cancer patients were prepared, using collagenase digestion to free the sinus histiocytes from the fibrous stroma of the nodes. The histiocytic cells so obtained were then characterized using four surface markers: Fc(IgG) receptors, C3 receptors, DR antigen and a macrophage-associated antigen (defined by the monoclonal antibody VEP-7). In addition phagocytosis was assessed using IgG-coated red cells, and both lysozyme and alpha-1-antitrypsin were localized by means of immunoperoxidase staining. The results demonstrated that the majority of sinus histiocytes carried surface macrophage markers, but that a minority displayed phagocytosis and the presence of lysozyme or alpha-1-antitrypsin.

Antigens, Surface↗
PubMed1986

Rehabilitation indicators: a complement to traditional approaches to patient assessment.

Rehabilitation Indicators (RI) form a multipart system for assessing the macrofunctioning of patients in medical rehabilitation. The RI system was designed to provide a holistic view of the patient as a means of integrating the diverse data sets that are obtained at present. The computerization of the RI system creates an easily accessible database to optimize intrateam communication and the sharing of information with patients and families, as well as to optimize the service provider's response to increasing demands for accountability.

Activities of Daily Living↗