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Biomedical subjects

D L Murray

Publications and source records attributed to D L Murray.

At least 73 records · Page 4Linked to original sources
PubMed1987

Receptors for 5-hydroxytryptamine in rabbit blood vessels: activation of alpha adrenoceptors in rabbit thoracic aorta.

Experiments were carried out to identify the receptors mediating the contraction of the rabbit thoracic aorta to 5-hydroxytryptamine (5-HT). Isolated aortic rings were mounted in tissue baths for the measurement of isometric contraction and 5-HT dose-response curves were obtained in the presence and absence of receptor antagonists. Prazosin, 1 X 10(-7) M, or 30-min pretreatment with 1 X 10(-5) M benextramine had no effect on the contractile response of aorta to 5-HT up to 1 X 10(-5) M, whereas 2 brom-D-lysergic acid diethylamide, 1 X 10(-7) M, shifted the 5-HT dose-response curve far to the right. Alpha receptor blockade with either prazosin or benextramine in the presence of 2 brom-D-lysergic acid diethylamide produced a greater blockade than that caused by 2 brom-D-lysergic acid diethylamide alone. When 5-HT dose-response curves were extended to 1 X 10(-3) M, three phases were identified. The first, a dose-related contraction, was mediated exclusively by serotonergic receptors. The second, a relaxation to approximately 40% of maximum, occurred at 1 X 10(-5) M and appeared to result from the rapid development of tachyphylaxis. The third phase was a dose-related contraction to concentrations of 5-HT above 1 X 10(-5) M and was inhibited by either prazosin or pretreatment with benextramine. Similar results were obtained in aortic rings from reserpine-pretreated rabbits. It is concluded that the contractile response to concentrations of 5-HT below 1 X 10(-5) M is mediated exclusively by serotonergic receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Inhibition of suppressor cell function by cimetidine in a murine model.

Immunomodulatory effects of cimetidine, an H2 histamine receptor antagonist, have been reported in humans and animals. To define these effects more clearly, the action of cimetidine on suppressor cell function was studied utilizing a murine model of contact hypersensitivity. Intravenous inoculation of BALB/c mice with DNP-coupled syngeneic spleen cells induced the production of DNP-specific suppressor cells which could easily be demonstrated by a reduction in ear swelling after contact sensitization with 1-fluoro-2,4-dinitrobenzene (DNFB) following transfer of spleen and lymph node cells to naive syngeneic recipients. Cimetidine treatment of animals in which suppressor cells were induced resulted in an inability of these mice to transfer cellular suppression as measured by development of a normal immunologic response in the recipient mice. The effect of cimetidine was both dose and time related. While all groups receiving cimetidine showed some loss of suppressor cell function, the maximum effect (up to 100% inhibition) was seen when 50 mg/kg of cimetidine was administered intraperitoneally 2 days before or on the day of suppressor cell induction. Some restoration also occurred when cimetidine was given after the day of induction. It has been shown that suppressor cells possess histamine receptors which may be involved in suppressor cell activation. The results indicate that cimetidine may inhibit the functioning of these receptors.

Animals↗
PubMed1986

Vasoconstrictor threshold synergism and potentiation in the rabbit isolated thoracic aorta.

Isolated rings of rabbit thoracic aorta were mounted in tissue baths for the measurement of isometric contraction, and the effects of combinations of two agonists were studied. Concentrations of methoxamine, clonidine, norepinephrine (NE), 5-hydroxytryptamine (5-HT) and potassium causing threshold contraction (0.1 g) were determined. Combinations of any two of these or of two doses of the same agonist elicited far greater than additive contractions ranging from 0.5 to 2.7 g. When dose-response curves to an alpha adrenergic agonist were obtained in the presence of a threshold concentration of the same or another alpha agonist, the curve was shifted to the left at threshold but converged with the control curve between ED10 and ED70. When 5-HT dose-response curves were obtained in the presence of either NE or methoxamine, the curve was shifted to the left in a parallel fashion. Both NE and methoxamine dose-response curves were also shifted to the left in a parallel fashion in the presence of 5-HT. The threshold concentration of potassium caused leftward parallel shifts of the dose-response curves for all agonists studied. These observations are consistent with the conclusion that the resting state of the rabbit thoracic aorta differs from the threshold contractile state and that this accounts for the far greater than additive contraction caused by combinations of two threshold doses of the same or different agonists. The first dose delivers sufficient stimulus to move the tissue from resting to threshold contractile state whereas the stimulus delivered by the second dose manifests entirely as contraction. This phenomenon affects primarily the threshold response.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Alpha-adrenergic receptors in rabbit eyes.

The IOP and pupil response to alpha-adrenergic agonists and blockers was studied in albino rabbits. Topical ocular application of solutions of methoxamine (alpha 1) and oxymetazoline (alpha 2) caused dose-related early rises in IOP which were inhibited by pretreatment with prazosin, an alpha 1-blocker, or with yohimbine, an alpha 2-blocker. Although both prazosin and yohimbine have ocular hypotensive activity, the effect on the early IOP rise did not appear to be related to this action. Prazosin and yohimbine also inhibited the early IOP rise after treatment with clonidine, a second alpha 2-agonist. Surgically sympathectomized rabbits showed little or no hypersensitivity to methoxamine or oxymetazoline when compared to non-operated normal rabbits. However the treated ipsilateral eyes showed a much greater increase in IOP than the treated contralateral eyes. There was little difference in the IOP response between clonidine-treated ipsilateral and contralateral eyes. Methoxamine and oxymetazoline caused dose-related increases in the pupil diameter which were blocked by the nonselective alpha-blocker phentolamine but not by prazosin (alpha 1) or yohimbine (alpha 2). This study suggests: 1) That the early IOP rise after treatment with alpha-agonists is due to stimulation of postsynaptic alpha 1-receptors, possibly located in superficial blood vessels in the anterior segment of the eye; 2) The mydriatic response to alpha-agonists appears to be mediated by alpha-receptors which differ from the classical alpha 1 and alpha 2 subtypes.

Adrenergic alpha-Agonists↗
PubMed1985

Mycobacterium marinum infection in a 4-year-old child.

Infections with Mycobacterium marinum are uncommon in children but should be considered by a physician confronted with chronic, poorly healing skin lesions. A case of such an infection in a 4-year-old child is presented. Presenting signs and symptoms, differential diagnosis, and treatment of these infections are discussed.

Axilla↗
PubMed1984

Perinatal bacterial infection after prolonged rupture of amniotic membranes: an analysis of risk and management.

Chi-square and logistic stepwise multiple regression analysis of perinatal determinants of infant bacterial infection following prolonged rupture of amniotic membranes for 24 hours or more prior to delivery was applied in 33 infected infants and 66 matched control infants from the NINCDS Collaborative Project. In order of statistical significance, the most important variables were placental inflammation (P = 0.002), gestational age less than 34 weeks (P = 0.008), gestational age 34 to 37 weeks (P = 0.013), male sex (P = 0.015), Apgar score less than 6 at 5 minutes (P = 0.023), and clinical amnionitis (maternal fever, fetal tachycardia, or amniotic or gastric fluid leukocytes or bacteria) (P = 0.044). Duration of labor during PROM, race, and maternal age and parity were insignificant. Using these predictive variables, identification of infected infants for either microbial surveillance (superficial and systemic cultures) or microbial surveillance and anticipatory antibiotic therapy (discontinued after 3 days of negative cultures) was highly significant (P = 0.0001). Incorporating these variables and derived coefficients from multivariate analysis, a mathematical model was used for evaluation and prediction of perinatal bacterial infection with a sensitivity of 82% and specificity of 70%. Analysis of 46 infants prior to and 310 infants after implementation of this process at Harbor-UCLA Medical Center indicated significant improvement in the appropriate management of these infants at risk (from 59% to 87% of the population, P less than 0.05). Inappropriate antibiotic therapy decreased from 35% to 10% (P less than 0.05). In the absence of a shift in the median days of hospitalization of non-PROM infants, determination of the grand median days of PROM infant hospital stay showed a decrease (P less than 0.01) after initiation of this evaluation and management scheme.

Amnion↗
PubMed1982

Postoperative neurosurgical infections due to bacillus species.

The cases of 2 patients with postoperative ventriculitis due to Bacillus species bacteria are presented. Bacillus licheniformis was isolated from one patient following removal of an intraventricular meningioma, and Bacillus cereus from another patient following placement of a ventriculoperitoneal shunt. Both isolates were resistant to a variety of antibiotics, but both were sensitive to gentamicin and chloramphenicol. These cases emphasize several points; (a) Bacillus species, usually thought to be nonpathogenic, may produce intracranial infections; (2) species identification is important for epidemiological purposes and for the selection of appropriate chemotherapeutic agents; and (3) in cases of suspected ventriculitis, chloramphenicol or gentamicin should be considered for Gram's staining revealing gram-positive bacilli. In addition, we recommend that when planning antibiotic prophylactic regimens, consideration should be given to including one of these agents to assure coverage of Bacillus species.

Adult↗
PubMed1982

Preclinical ocular evaluation of noncorticosteroidal antiinflammatory agents.

The nature of inflammation in general and the special aspects of ocular inflammation are discussed. Causes of inflammation, the cellular and tissue response to noxious stimuli and the biochemical mediation of the inflammatory response are described. Prostaglandins and their relatives the thromboxanes and prostacyclins are shown to play an important role in the mediation of ocular inflammation. Inhibitors of the biochemical synthesis of prostaglandins show strong potential for use in topical ocular antiinflammatory therapy, however their preclinical evaluation requires the choice of a suitable animal model. A review of animals of both specific and general ocular inflammation is presented.

Animals↗
PubMed1982

Multiple splenic aspergillomas in a patient with acute lymphoblastic leukemia.

A case of multiple splenic aspergillomas (mycetomas) without systemic involvement is a patient with acute lymphoblastic leukemia is described. The patient underwent splenectomy without concomitant antifungal therapy. There has been no recurrence of the disease for over two years. Granulocytopenia and airborn contamination may have played a role in the acquisition of this disease. The value of serology, radionuclide scans and cultures in the diagnosis of Aspergillus infections is explored. The role of granulocyte transfusions, antifungal chemotherapy and the achievement of bone marrow remission in localization of the fungal disease is discussed.

Adolescent↗
PubMed1981

Pyogenic osteomyelitis versus pseudo-osteomyelitis in Gaucher's disease. Report of a case and review of the literature.

Presented is a young girl with Gaucher's disease who developed acute bone pain accompanied by signs of inflammation and who was felt to have possible pyogenic osteomyelitis. The lack of significant pathogenic bacterial growth on culture and the findings at orthopedic surgery led the authors to conclude that this child probably represented a case of pseudo-osteomyelitis, but the isolation of an anaerobe from the operative culture of the involved bone leaves the exact diagnosis unclear. Since this child underwent an open surgical procedure, she was treated with antibiotics to prevent the possible development of chronic osteomyelitis. This anaerobic growth on culture, although strongly felt to be a contaminant, also played a role in this decision. She had an uneventful hospital course and subsequently has done well. It is suggested that great caution be taken before subjecting a patient with Gaucher's disease to orthopedic surgical procedures. If pyogenic osteomyelitis is strongly suspected, obtaining multiple blood cultures and culture by needle aspirate may be preferred over an open surgical procedure. The use of empiric antibiotic therapy without an attempt at further diagnosis is not recommended. If an orthopedic surgical procedure is necessary in a patient with Gaucher's disease, antibiotic coverage is indicated and long-term observation of the operative sight for drainage and/or other signs of chronic inflammatory changes in mandatory.

Child↗