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Biomedical subjects

G Rich

Publications and source records attributed to G Rich.

At least 19 recordsLinked to original sources
PubMed2001

Detection of intracytoplasmic cytokines by flow cytometry in adenoids and peripheral blood lymphocytes of children.

Cytokine flow cytometry at the single-cell level has never been utilized in the study of adenoidal lymphocytes. We describe the multiparameter capability of flow cytometry to simultaneously detect an antigen on the surface of the adenoidal and peripheral blood lymphocytes and detect Th1 and Th2 cytokines within the cytoplasm of these lymphocytes. The data suggest that the percentage of cells producing interferon (IFN)-gamma are decreased in adenoidal as compared to peripheral blood lymphocytes, confirming our previous studies. The new findings show that the CD8 subset of adenoidal lymphocytes produces lower amounts of IFN-gamma as compared to peripheral blood CD8 cells. The intracytoplasmic synthesis of interleukin (IL)-2, however, appears to be similar in both adenoidal and peripheral blood lymphocytes. The CD4 subset of lymphocytes in the adenoid produces more IL-2, whereas the CD8 subset produces more IFN-gamma. Finally, as shown in our previous studies, the Th2 cytokines appear to be produced in similar quantities in both adenoidal and peripheral blood lymphocytes.

Adenoidectomy↗
PubMed1998

Regulation of prostaglandin H synthase-2 expression in cerebromicrovascular smooth muscle by serum and epidermal growth factor.

Growth factors may play a role in the formation of prostaglandins (PG) by cerebral blood vessels during development or reaction to injury. In smooth muscle cultures isolated from murine cerebral microvessels PG production was induced with either serum or epidermal growth factor (EGF). Prostaglandin H synthase (PGHS) activity peaked at 6 h after the addition of 10% serum or 50 ng/ml EGF. Increases in expression of PGHS-1 mRNA were small (7- to 10-fold) compared with PGHS-2 (30- to 120-fold), and the induction patterns were different for serum and EGF. An increase in PGHS-2 message was detected by 0.5 h of adding either agent, but peak induction occurred earlier for EGF than for serum, 1 h vs. 3 h, respectively. The response to either stimulus had returned to prestimulation levels by 12 h. The induction of PGHS-2 protein was also transient, but followed a more delayed time course (peak levels at 6 h). Induction of activity, message, and protein by either agent was blocked by 1 microM dexamethasone and attenuated by genistein (100 microM), a nonspecific tyrosine kinase inhibitor. Tyrphostin 47, a more selective EGF receptor tyrosine kinase inhibitor, dose-dependently inhibited EGF-stimulated PGHS activity, completely abolishing PG production at 100 microM. However, this inhibitor had no effect on serum-stimulated PG production. Curiously, 100 microM tyrphostin 47 enhanced EGF-induced PGHS-2 mRNA and protein expression. These data suggest that EGF induces the expression of PGHS-2 in cerebromicrovascular smooth muscle by a mechanism that requires tyrosine kinase activity and that is distinct from serum.

Animals↗
PubMed1998

Comparison of PCR and microscopy for detection of Cryptosporidium parvum in human fecal specimens: clinical trial.

PCR technology offers alternatives to conventional diagnosis of Cryptosporidium for both clinical and environmental samples. We compared microscopic examination by a conventional acid-fast staining procedure with a recently developed PCR test that can not only detect Cryptosporidium but is also able to differentiate between what appear to be host-adapted genotypes of the parasite. Examinations were performed on 511 stool specimens referred for screening on the basis of diarrhea. PCR detected a total of 36 positives out of the 511 samples, while routine microscopy detected 29 positives. Additional positives detected by PCR were eventually confirmed to be positive by microscopy. A total of five samples that were positive by routine microscopy at Western Diagnostic Pathology but negative by PCR and by microscopy in our laboratory were treated as false positives. Microscopy therefore exhibited 83.7% sensitivity and 98.9% specificity compared to PCR. PCR was more sensitive and easier to interpret but required more hands-on time to perform and was more expensive than microscopy. PCR, however, was very adaptable to batch analysis, reducing the costs considerably. Bulk buying of reagents and modifications to the procedure would decrease the cost of the PCR test even more. An important advantage of the PCR test, its ability to directly differentiate between different Cryptosporidium genotypes, will assist in determining the source of cryptosporidial outbreaks. Sensitivity, specificity, ability to genotype, ease of use, and adaptability to batch testing make PCR a useful tool for future diagnosis and studies on the molecular epidemiology of Cryptosporidium infections.

Animals↗
PubMed1998

14,15-Epoxyeicosatrienoic acid inhibits prostaglandin E2 production in vascular smooth muscle cells.

14,15-Epoxyeicosatrienoic acid (EET), a cytochrome P-450 epoxygenase product of arachidonic acid (AA), reduced PGE2 formation by 40-75% in porcine aortic and murine brain microvascular smooth muscle cells. The inhibition was reversed 6-10 h after removal of 14,15-EET from the medium and was regioisomeric specific; 8,9-EET produced a smaller effect, whereas 11,12- and 5,6-EET were ineffective. Although the cells converted 14,15-EET to 14, 15-dihydroxyeicosatrienoic acid (14,15-DHET), 14,15-DHET did not inhibit PGE2 formation, and the 14,15-EET-induced inhibition was potentiated by 4-phenylchalcone oxide, an epoxide hydrolase inhibitor. The inhibition occurred when substrate amounts of AA were used and was not accompanied by enhanced production of other PGs, suggesting an effect on PGH synthase; however, in murine cells, 14, 15-EET did not reduce PGH synthase mRNA or protein. Moreover, the 14, 15-EET-induced decrease in PGE2 production was overcome by increasing the concentration of AA, but not oleic acid (which is not a substrate for PGH synthase). These findings suggest that 14,15-EET competitively inhibits PGH synthase activity in vascular smooth muscle cells. The 14,15-EET-induced inhibition of PGE2 production resulted in potentiation of platelet-derived growth factor-induced smooth muscle cell proliferation, suggesting that the competitive inhibition of PGH synthase by 14,15-EET can affect growth responses in smooth muscle cells.

8,11,14-Eicosatrienoic Acid↗
PubMed1997

Chymopapain-induced reduction of proinflammatory phospholipase A2 activity and amelioration of neuropathic behavioral changes in an in vivo model of acute sciatica.

The mechanism of action underlying chymopapain (Chymodiactin) chemonucleolysis remains obscure. Radiographic studies suggest that chymopapain does not alter disc fragment size acutely; nonetheless, patients often report symptom resolution within a few days, even hours, of treatment. The authors postulate that, in addition to its chemonucleolytic action, chymopapain may possess antiinflammatory properties. To test this hypothesis, the authors assessed the ability of chymopapain to modulate the activity of the proinflammatory enzyme phospholipase A2 (PLA2) and to ameliorate behavioral changes associated with inflammatory neuropathy in an in vivo model of sciatica. Thirty-nine male Fischer rats were randomly assigned to one of three treatment groups: 1) saline, 2) betamethasone, or 3) chymopapain. All of the rats underwent unilateral sciatic nerve ligation with loose chromic gut suture to induce inflammatory mononeuropathy. The animals were tested for thermal and mechanical hyperalgesia on Days 0 (preoperation), 7 (pretreatment), and 14 (prior to death). Three animals were killed on Day 0 to determine the baseline PLA2 activity within unmanipulated rat sciatic nerves. On Day 7, three animals from each group were killed to assess PLA2 activity prior to treatment. The remainder were given a single infusion of saline, betamethasone (0.3 mg/kg), or chymopapain (100 pKat U) around the inflamed nerve. On Day 14, the remaining animals were killed and their sciatic nerves were removed. The tissue was homogenized and the PLA2 activity was determined using [14C]arachidonate-labeled Escherichia coli phospholipid membrane as a substrate. Lipids were extracted and separated by thin-layer chromatography. All animals developed behavioral changes consistent with inflammatory mononeuropathy 24 to 72 hours postoperatively; these included gait disturbance, flexion deformity, and hyperalgesia of the involved hindlimb. The degree of mechanical and thermal hyperalgesia was comparable between groups at Day 7. By Day 14, the thermal hyperalgesia had resolved; the mechanical hyperalgesia was less evident in the betamethasone- and chymopapain-treated groups than in the saline-treated controls (p = 0.003; saline- vs. chymopapain-treated groups p = 0.004; saline- vs. betamethasone-treated groups p = 0.008). The mean PLA2 activity at baseline (Day 0) was 11.6 +/- 4.9 nmol phospholipid hydrolyzed per minute per milligram of protein. The PLA2 activity at Day 7 was 74.4 +/- 18.2 (ligated side) and 21.2 +/- 11.7 (nonligated side). At Day 14, PLA2 activity was reduced in the chymopapain- (47.8 +/- 12.3) and betamethasone- (39.7 +/- 9.5) treated groups compared with the saline control group (62.3 +/- 11.2), (saline- vs. chymopapain-treated groups p < 0.05; saline- vs. betamethasone-treated groups p < 0.01). The PLA2 activity in nonligated specimens was 18.6 +/- 10.1. These data indicate that chymopapain exhibits antiinflammatory properties in vivo, reducing PLA2 activity and ameliorating mechanical hyperalgesia in this model of inflammatory sciatic neuropathy.

Acute Disease↗
PubMed1996

Salt sensitivity of hypertension and responses to angiotensin converting enzyme inhibition with benazepril.

Salt intake, and the sensitivity of blood pressure (BP) to excessive salt intake is thought to contribute to the pathogenesis of essential hypertension in some patients. This study was designed to ascertain whether salt sensitivity of BP is a determinant of BP and renal vascular responsiveness to angiotensin converting enzyme (ACE) inhibition. In 24 patients with essential hypertension, ranging in age from 30 to 68 years, renin status, renal hemodynamics, and sensitivity of BP to steady state changes in salt intake were assessed. Twenty-four hour ambulatory BP monitoring (ABPM) was employed to measure baseline BP and BP response to 4 weeks' treatment with benazepril at 20 or 40 mg/day. Benazepril induced a highly-significant reduction in BP (P < .001) and increase in renal plasma flow (530 +/- 17 to 580 +/- 19 mL/min/1.73 m2; P < .001). Systolic BP fell from 143 +/- 2 to 129 +/- 2 mm Hg (P < .001), and diastolic BP fell from 91 +/- 1.6 to 80 +/- 2 mm Hg (P < .001). The magnitude of the BP and renal vascular response to ACE inhibition was not influenced by the sensitivity of BP to salt intake. In a multivariate analysis neither body mass index nor age influenced the BP response to ACE inhibition or the relationships between salt intake and a BP response to ACE inhibition. We conclude that the factors that influence sensitivity of BP to salt intake do not influence the systemic or renal hemodynamic response to ACE inhibition.

Adult↗
PubMed1996

Prostaglandin production in cultured cerebral microvascular smooth muscle is serum dependent.

To expand the understanding of cerebrovascular eicosanoid metabolism, the ability of smooth muscle isolated from murine cerebral microvessels to produce prostaglandins (PGs) was studied in vitro. Cultures from SJL and BALB/c mice produced primarily prostaglandin E2 (PGE2) and I2 (PGI2) in response to exogenous arachidonate and calcium ionophore as well as the agonists acetylcholine and epinephrine. Subconfluent smooth muscle cultures demonstrated a two- to threefold increased capacity to produce PG compared with confluent cultures. In contrast, serum deprivation of smooth muscle caused an 80-90% diminution in both PGE2 and PGI2 production but had no effect on PG release in cerebromicrovascular endothelium. Reintroduction of serum to smooth muscle restored PG production within 6h, and the restoration was inhibited by 1 microM dexamethasone. Message for both prostaglandin H synthase (PGHS)-1 and -2 was detectable in smooth muscle grown in the presence of serum, but PGHS-2 message was not present in serum-deprived cultures. Furthermore, readdition of serum induced a massive increase in PGHS-2 mRNA with only a small increase in PGHS-1 message. The serum induction of PGHS-2 was corroborated by immunohistochemistry and Western blotting. Thus cerebromicrovascular smooth muscle may contribute significantly to the formation of PG under circumstances likely to be present during central nervous system pathologies. The induction of PGHS, particularly PGHS-2, may play a key role in this process.

Animals↗
PubMed1994

Astrocyte-derived lipoxygenase product evokes endothelium-dependent relaxation of the basilar artery.

The goal of this study was to examine the possible production of vasoactive factors by astrocytes. We consistently observe that rat astroglial cells in suspension produce marked relaxation when added to precontracted rings of intact (but not endothelium-denuded) rabbit basilar artery. The ultimate mediator of this relaxation was endothelium-derived nitric oxide whose synthesis is activated by an as yet unidentified factor(s) produced tonically by astrocytes. The factor is relatively stable, and is not arachidonate, or a product of cyclooxygenase or P450 metabolism. Based upon studies with selective inhibitors, the factor appears to result from 12- or 15-lipoxygenase metabolism, the products of which are known to be vasoactive. In a separate series of experiments, astrocyte-conditioned medium stimulated the production of citrulline from L-arginine by nitric oxide synthase in bovine aortic endothelial cells. The possible significance for central nervous system (CNS) pathophysiology of an astrocyte-derived vasodilator is discussed.

Amino Acid Oxidoreductases↗
PubMed1989

Privatisation.

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Australia↗
PubMed1988

The epidemiology of Neisseria gonorrhoeae isolates from Western Australia based on antibiotic resistance and plasmid profiles.

Two collections of 90 distinct isolates of Neisseria gonorrhoeae were examined with respect to their plasmid profiles, auxotypes and antibiotic sensitivities to penicillin, erythromycin, streptomycin, spectinomycin, sulphamethoxazole, tetracycline and trimethoprim. The two series, collected from 1976-1981 and from 1985-1986 possessed similar sensitivity patterns except for erythromycin and trimethoprim. The earlier collection of penicillinase producing N. gonorrhoeae (PPNG) was found to be significantly more resistant to both these antibiotics. Within each series the PPNG isolates were more resistant to penicillin and streptomycin than the non-PPNG. All PPNG isolates had the 4.4 X 10(6) dalton penicillinase plasmid and frequently exhibited an auxotype which included a requirement for proline. The frequency of the 24.5 X 10(6) dalton transfer plasmid in the non-PPNG was found to have increased threefold from the early collection to the later one while amongst the PPNG the frequency of the transfer plasmid was seen to decrease. Auxotyping results indicated that the transfer plasmid played a significant role in the spread of the penicillinase plasmid in the early collection. In the later collection a transfer-plasmid-free strain, which required only proline, comprised almost half of the penicillinase producers and this PPNG strain now appears to be adapted to our environment.

Gonorrhea↗
PubMed1987

A case of factitious disorder presenting as plumbism.

The case of a young man who presented with lead poisoning is reported. This did not resolve with prolonged treatment and he had several unusual and unexplained bacteraemias. Probable sources of self-administered lead and bacteria were demonstrated and psychiatric assessment showed that the patient had a personality disorder which was consistent with a diagnosis of factitious disorder. Psychiatric management led to the termination of the self-inflicted illnesses and enabled the patient to cope with his personal and social problems.

Adult↗
PubMed1985

Trimethoprim.

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Anti-Infective Agents, Urinary↗