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Biomedical subjects

R Murphy

Publications and source records attributed to R Murphy.

At least 19 recordsLinked to original sources
PubMed1992

Roles of peptides in transmission in the enteric nervous system.

Studies of the enteric nervous system have proved to be important in the development of new concepts of the chemical nature of transmission from neurons. In particular, they have revealed the multiplicity of influences that peptides can have on transmission, such as their action as primary transmitters, and the fact that they often act as co-transmitters in enteric neurons. However, in other cases no roles can be attributed to neuropeptides in enteric neurons, and their involvement in short-term changes in excitability seems minor.

Animals↗
PubMed1992

The antimicrobial effect of an iron-binding agent on Streptococcus mutans.

The antimicrobial activity of 2,2'-bipyridine, an iron-binding agent, was investigated by incorporating this agent into Scotchbond dental adhesive resin. The growth of Streptococcus mutans on the surface of resin, media and culture vessel was determined by optical density measurements. It was observed that 2,2'-bipyridine exhibited excellent antimicrobial properties.

2,2'-Dipyridyl↗
PubMed1992

Neurogenic bladder dysfunction in lumbar intervertebral disc prolapse.

Lumbar disc prolapse with urinary dysfunction is an uncommon condition. The clinical, pathological and follow-up details of 30 patients are presented. Detrusor recovery is rare and most patients are left with an areflexic bladder. Female patients with lumbar disc prolapse and an areflexic detrusor who strain to empty their bladders are likely to develop genuine stress incontinence. This may be managed by the early institution of intermittent self-catheterisation, which may reduce the need for incontinence surgery.

Adult↗
PubMed1992

The progression of untreated HIV-1 infection prior to AIDS.

Using a case-control study of untreated men, we investigated the physical, mental, and economic effects of human immunodeficiency virus (HIV-1) infection prior to the diagnosis of acquired immunodeficiency syndrome (AIDS). Beginning 2 to 2.5 years prior to AIDS, case subjects reported more of 12 HIV-1 related symptoms and during the year prior to AIDS, at least 30.6 extra days of these symptoms than did control subjects. Within the 6 months preceding AIDS, case subjects' unemployment rose to 9% (P < or = .05) and depression to 34.2% (P < or = .001). At 6 to 12 months and within 6 months before AIDS, 17.1% and 31.5%, respectively, were anemic, while 37.7% and 64.7% had CD4+ counts less than 200 x 10(6)/L. Diagnosing AIDS at CD4+ counts less than 200 x 10(6)/L could significantly reduce pre-AIDS morbidity. Other implications of these findings are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Risk of developing cytomegalovirus retinitis in persons infected with the human immunodeficiency virus.

This study examines the risk of developing cytomegalovirus (CMV) retinitis as a function of the duration and degree of CD4+ lymphocyte depletion. A retrospective analysis of 135 persons infected with the human immunodeficiency virus (HIV) was performed. Kaplan-Meier estimates for the percentage of patients developing CMV retinitis during the 27-month study period were calculated. Twenty-six patients were diagnosed as having CMV retinitis. In 14 of these patients, T cell phenotyping was done within the 3 months preceding diagnosis. The mean CD4+ lymphocyte count for these patients was 15.6 cells/mm3 (range, 2-33/mm3). At 27 months, the percentage of patients developing CMV retinitis with baseline CD4+ lymphocyte counts of 0-50, 51-100, and 101-250 cells/mm3 was 41.9%, 26.3%, and 14.7%, respectively (log-rank test, p = 0.003). The odds ratio for developing CMV retinitis for those with baseline CD4+ lymphocyte counts of 0-50 cells/mm3 compared with those with CD4+ lymphocyte counts of 101-250 cells/mm3 was 4.62 (p = 0.002). Twenty-four patients had CD4+ lymphocyte counts of < or = 50 cells/mm3 for an average of 13.1 months prior to diagnosis. Twenty-two patients had an acquired immune deficiency syndrome (AIDS)-defining illness diagnosed for an average of 18.0 months prior to the onset of retinitis. CMV retinitis is most likely to develop in patients with AIDS when the CD4+ lymphocyte count is < or = 50 cells/mm3.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Evidence that nitric oxide participates in non-adrenergic inhibitory transmission to intestinal muscle in the guinea-pig.

The possible involvement of nitric oxide (NO) in non-adrenergic nerve-mediated relaxations of guinea-pig gastrointestinal smooth muscle was investigated using longitudinal muscle that lies between the taenia of the caecum. Relaxations induced by electrical field stimulation in this preparation are similar to those described in other preparations of guinea-pig intestinal muscle when enteric inhibitory neurons are stimulated; they were blocked by tetrodotoxin (10(-6) M) but were unaffected by guanethidine (10(-6) M). N-Nitro-L-arginine (NOLA) (5 x 10(-5) to 10(-4) M), an inhibitor of NO synthase, and haemoglobin (10(-5) M), which reduces bioavailability of NO, both reduced the amplitude of nerve-mediated relaxations to less than 50%, without affecting the ability of the muscle to relax. These results suggest that NO may play a role in inhibitory neurotransmission to this preparation.

Animals↗
PubMed1991

Marsupial possum neurotensin: a unique mammalian regulatory peptide exhibiting structural homology to the avian analogue.

Neurotensin has been isolated from small intestinal extracts of an Australian marsupial, the brush-tailed possum (Trichosurus vulpecula). The primary structure was determined as: pGlu-Leu-His-Val-Asn-Lys-Ala-Arg-Arg-Val-Tyr-Ile-Leu. When compared with bovine neurotensin, marsupial possum neurotensin exhibits four amino acid substitutions. His for Tyr3, Val for Glu4 and Ala for Pro7 are identical with those found in chicken neurotensin. In addition, substitution of Pro10 with Val is unique among all neurotensins sequenced to date. Marsupial possum neurotensin is therefore of unique primary structure, displaying most sequence homology with its avian counterpart. This neurotensin may thus resemble the phylogenetic precursor present at the time of divergence of primitive mammals and birds.

Amino Acid Sequence↗
PubMed1991

Comparison of the presence and actions of substance P and neurokinin A in guinea-pig taenia coli.

The presence and sites of action of two closely related tachykinins, substance P (SP) and neurokinin A (NKA), were examined in the taenia coli of the guinea-pig. SP- and NKA-like immunoreactivity (LI) were demonstrated histochemically in nerve fibres supplying the taenia. Chromatographic characterization of aqueous acetic acid extracts of taenia showed only one peak of SP-LI, corresponding in retention time to authentic SP, whereas there were multiple peaks of NKA-LI, the major one of which corresponded to authentic NKA. SP-LI and NKA-LI, determined by radioimmunoassay, were in a molar ratio of SP equivalents to NKA equivalents of 8.5:1 in taenia extracts. Extrinsic denervation of the caecum had no significant effect on the concentration of either SP-LI or NKA-LI or on their immunohistochemical distributions. Both SP and NKA (10(-10) to 10(-5) M) caused contractions of the taenia that were unaffected by hyoscine (10(-6) M), mepyramine (10(-6) M) or tetrodotoxin (5 x 10(-7) M), indicating that both peptides act directly on the smooth muscle of the taenia. Contractions to SP occurred after a short, but concentration-dependent, delay, reached a peak quickly, and then decayed. In contrast, NKA caused contractions after longer latencies, the peak was reached more slowly, and the response was maintained for up to 10 min. (D-Pro2, D-Trp7,9)-SP (10(-5) M) antagonised responses to SP and NKA to a similar degree. It is concluded that both NKA and SP should be considered as transmitter candidates for non-cholinergic nerve-mediated excitation in the taenia.

Animals↗
PubMed1991

Computer-assisted image analysis of skin surface replicas.

Using a rubber-based dental impression material, negative surface impressions were made of demarcated areas of skin and prepared as dry specimens for scanning-electron microscopy. Electron micrographs were taken at low magnification and, using a programmed computer-assisted image analyser, it was possible to represent quantitatively the topography of that particular body site according to the degree of circularity of the various geometric subunits. This technique was most applicable to skin topography with a reliable geometrical pattern of triangles and squares, a feature of hair-bearing surfaces in general and in particular, the antecubital fossa. Using standardized trauma of various types the origin of skin surface markings were found to be located in the dermis. The technique was applied to the healing of experimental trauma produced by tape stripping, the resolution of clinical eczema and a comparison of steroid-treated and untreated tape-stripped skin.

Eczema↗
PubMed1991

Epidemiologic patterns of upper respiratory illness and Pneumocystis carinii pneumonia in homosexual men.

The relationship between self-reported upper respiratory illness symptoms (URI) and human immunodeficiency virus Type 1 (HIV-1) was examined in homosexual men using semiannual visits from 1984 to 1988. Temporal and geographic patterns of Pneumocystis carinii pneumonia (PCP) diagnosis in these men during the same time period are also described. URI, including acute sinusitis, was reported more often by 916 HIV-1-seropositive participants than by 2,161 seronegative participants (32.21 versus 28.86% p less than 0.001). For 387 seropositive subjects who progressed to acquired immunodeficiency syndrome (AIDS), the proportion reporting URI peaked one visit pre-AIDS at a level significantly higher than matched control subjects (0.45 versus 0.28, p less than or equal to 0.001). The peak was higher for those with PCP as an initial diagnosis. Reported URI peaked in winter and troughed in summer, and PCP diagnosis rates peaked and troughed 4 months later, respectively. Cities with the highest reported rates of URI also had the highest proportions of AIDS cases with PCP as an initial diagnosis. No temporal or geographic patterns were observed for other HIV-1-related symptoms or non-PCP AIDS diagnoses. These patterns suggest the possibility of a person-to-person transmission of P. carinii similar to that of other respiratory pathogens, which would imply a need to consider stricter methods to prevent nosocomial transmission of this pathogen in inpatient and outpatient settings. Further investigation of these issues is needed.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Stimulation of astroglial 5-HT1A receptors releases the serotonergic growth factor, protein S-100, and alters astroglial morphology.

Stimulation of astroglial 5-HT1A receptors causes astroglial cells to acquire a more mature morphology and to release a factor (or factors) which promotes growth of serotonergic neurons. By using an antibody-blocking approach, we have shown that at least one of the growth-promoting factors thus released is the astroglial-specific protein S-100. This may be a particularly important observation, in view of studies implicating S-100 in both Down's syndrome and Alzheimer's disease.

Animals↗
PubMed1990

Isolation of HIV-1 from monocytes of individuals negative by conventional culture.

To improve isolation of human immunodeficiency virus (HIV) from purified monocytic cell populations, a differential culture technique was applied to blood from HIV-seropositive individuals, culture-negative for HIV by routine culture. When 206 individuals were grouped by percentage of CD4+ lymphocytes, increases in viral isolation rates were significantly associated with declines in percentage of CD4+ cells (P less than .0001). Of 158 asymptomatic individuals, 78% had greater than 400 CD4+ lymphocytes/mm3. Only 19% were culture-positive using routine methods. Separation of peripheral blood mononuclear cells (PBMC) into purified lymphocyte and monocyte subpopulations for 12 asymptomatic patients and subsequent HIV culture of each purified subpopulation using three different indicator cell lines resulted in 100% virus recovery from purified monocytes cultured in the U-937 promonocytic cell line. Culture of purified lymphocytes in U-937 cells did not increase the isolation rate, whereas culture of patient PBMC in U-937 indicator cells and in allogeneic monocytes resulted in a 50% increase in HIV isolation. A monocytic indicator cell line added to routine culture methods may improve virus recovery from asymptomatic individuals.

Acquired Immunodeficiency Syndrome↗