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N Gibbons

Publications and source records attributed to N Gibbons.

50 records · Page 3Linked to original sources
PubMed1992

Long term effects of morphine on mesangial cell proliferation and matrix synthesis.

Since focal glomerulosclerosis is the predominant glomerular lesion in heroin nephropathy and since mesangial expansion is considered to be a precursor of glomerulosclerosis, we have evaluated the effect of opiates on mesangial cell (MC) proliferation and matrix synthesis. We showed, using a fluorometric assay, that MC are not capable of metabolizing heroin to its active metabolite morphine. Cells exposed to morphine (10(-5) M or 10(-4) M) in prolonged cultures either continuously (Group A) or intermittently (Group B) showed enhanced incorporation of [3H]thymidine when compared to control cells (control, 88600 +/- 26303 cpm/well vs. morphine 10(-4) M-Group A, 321203 +/- 52867, P less than 0.001; control vs. morphine 10(-4) M-Group B, 223126 +/- 46866 cpm/well, P less than 0.01; control, 107593 +/- 42284 cpm/well vs. morphine 10(-5) M - Group A, 267108 +/- 41866 cpm/well, P less than 0.001; control vs. morphine 10(-5) M - Group B, 202317 +/- 24325 cpm/well, P less than 0.05). However, MC incubated with a lower concentration of morphine (10(-6) M) enhanced DNA synthesis when exposed intermittently only (control, 107593 +/- 42284 cpm/well vs. Group B, 219164 +/- 15552 cpm/well, P less than 0.05). This growth stimulating effect of morphine (10(-6) M and 10(-5) M) was also observed at earlier time points, that is, one- and one-and-a-half-week old cultures. However, in one-week-old cultures. morphine in a higher concentration (10(-4) M) showed a suppressive effect (P less than 0.05) on MC proliferation (morphine, 3620 +/- 220 cpm/well vs. control, 4668 +/- 410 cpm/well). This effect not only subsided by one and a half weeks but morphine (10(-4) M) treated cells enhanced MC proliferation. An opioid antagonist, naloxone attenuated the effect of morphine in one and half week old cultures. Morphine at 10(-6) M to 10(-4) M concentrations enhanced incorporation of [3H]proline in the extracellular proline pool (a component of mesangial matrix) when compared to control (control, 309661 +/- 3992 vs. morphine 10(-4) M, 363104 +/- 10539 cpm/well, P less than 0.05 or morphine 10(-5) M, 397954 +/- 31008 cpm/well, P less than 0.001 or morphine 10(-6) M, 384630 +/- 26369 cpm/well, P less than 0.01). In addition, MC incubated with morphine (10(-6) M and 10(-4) M) also enhanced (P less than 0.001) synthesis of laminin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Specific receptors for beta-endorphin on mesangial cells.

beta-Endorphin is an endogenous opioid considered to be a modulator of immune injury. We studied the binding of [125I]beta-endorphin on cultured rat mesangial cells at 4 and 37 degrees C. The results were analyzed by computer program (Ligand). Incubation of rat mesangial cells with unlabeled beta-endorphin displaced [125I]beta-endorphin in a concentration-dependent manner. The binding of [125I]beta-endorphin was not affected by either opiate agonists or antagonists. Saturation studies at 37 degrees C revealed that beta-endorphin binding was time dependent. Binding studies revealed the presence of a single class of high-affinity binding sites with an apparent Kd of 15.3 nM. The number of receptor sites was calculated as 8.48 x 10(5) sites/cell. Mesangial cells exposed to beta-endorphin (10(-6) M) for 48 h showed enhanced incorporation of [3H]thymidine when compared to untreated cells (control, 23,228 +/- 2,778 cpm/well vs. beta-endorphin, 44,887 +/- 4,259 cpm/well; p less than 0.01). Our results show that mesangial cells carry a specific receptor for beta-endorphin which may be linked to proliferation of mesangial cells.

Animals↗
PubMed1992

Effects of angiotensin II and arginine vasopressin on F-actin content of cultured mesangial cells.

The actin cytoskeleton of mesangial cells (MC) plays an important role in the contractile response to agonists as well as in the endocytosis of macromolecules. A quantitative study of the F-actin content of MC by the rhodamine-phalloidin binding assay was carried out. Angiotensin II (ANG II) (10(-6) M) significantly increased the F-actin content of MC by 30 min and at later time periods, with increases ranging from 31 to 46%. Arginine vasopressin (10(-8) M) produced a transient decrease of F-actin content of MC at 30 s but then significantly enhanced the F-actin content at later time periods. There was no change in total actin and protein content of MC at 30 min in the presence of either agent. Thus, the increase in F-actin is related to a shift in the G- to F-actin ratio and not to the synthesis of new F-actin. Because the incubation of MC with 1 (5-isoquinolinylsulfonyl)-2-methylpiperazine, an inhibitor of protein kinase C, did not attenuate the ANG II-induced increase in the F-actin content of MC, the shift does not appear to be mediated by the activation of protein kinase C. The removal of external calcium did not prevent the increase in F-actin. Dibutyryl cAMP (5 x 10(-4) M), a smooth muscle cell and MC relaxant, did not alter the F-actin content in MC, and 10(-5) M cytochalasin B significantly lowered F-actin content.(ABSTRACT TRUNCATED AT 250 WORDS)

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1991

Septicaemia caused by Pediococcus pentosaceus: a new opportunistic pathogen.

A case of septicaemia caused by Pediococcus pentosaceus is described. The role played by pediococci, and other vancomycin-resistant Gram-positive cocci, in disease states is examined. We suggest that in immunocompromised patients these organisms act as opportunist pathogens. This would appear to be the first reported case of P. pentosaceus septicaemia.

Ampicillin↗
PubMed1990

A fish oil diet preserves renal function in nephrotoxic serum nephritis.

Fish oil diets preserve renal function in murine lupus, but we have found that these diets accelerate renal deterioration in renoprival nephropathy. In this study we examined the effects of dietary fish oil in accelerated nephrotoxic serum nephritis. For 1 month, 14 female rats were fed diets that differed only in fat composition, containing either menhaden (fish) oil or beef tallow (control). Rats were then preimmunized with rabbit IgG and, 5 days later, were injected with nephrotoxic serum. Glomerular filtration rate (GFR) was measured continuously in conscious animals by means of intraperitoneal 14C-labeled inulin minipumps. Fish oil-containing diets markedly attenuated the nephrotoxic serum-induced decline in GFR and the rise in proteinuria and significantly reduced glomerular prostaglandin E2 and thromboxane A2. The results of tests of renal histology showed no differences between the two groups. Five days after preimmunization, rats fed fish oil had more rabbit IgG remaining in their serum and had mounted less of an antibody response to the rabbit IgG. Fish oil diets also resulted in an attenuated disappearance of injected 14C-labeled rabbit IgG. In vitro, peritoneal macrophages from rats fed fish oil took up less rabbit IgG than macrophages from rats fed control diets. Thus the beneficial effects of a fish oil diet may result from defective immune surveillance and from alterations in eicosanoids.

Animals↗
PubMed1990

Effects of fish oil on glomerular function in rats with diabetes mellitus.

The mechanisms responsible for hyperfiltration in diabetes mellitus (DM) as well as for the initiation and progression of diabetic nephropathy are not fully elucidated. Enhanced prostaglandin E2 (PGE2) production has been invoked in the former and thromboxane (TXB2) and hyperlipidemia in the latter. Fish oil (FO)-enriched diets can favorably alter eicosanoid synthesis and serum lipid profiles. We therefore examined the effects of a FO-enriched diet on glomerular filtration (GFR), proteinuria, glomerular eicosanoid production, and serum lipids in rats with streptozotocin-induced DM (STZ-DM). Groups of 5-8 rats with STZ-DM were maintained on low insulin and then pair-fed with isocaloric diets enriched with either FO (20% w/w) or beef tallow (BT; 20% w/w). GFR was determined in the same animals at onset of diet and after 8 and 20 weeks on the respective diets by [14C]inulin clearance using implanted osmotic minipumps each time. Significant hyperfiltration was present initially and GFR did not change on either diet for 20 weeks, in spite of a significant and greater than 50% decrease in all prostaglandins (PGE2, TXB2, PGF2 alpha, 6-keto, PGF1 alpha) produced by glomeruli isolated from DM/FO as compared to DM/BT or control rats. FO diet completely corrected the hypertriglyceridemia of diabetes and significantly reduced the mild and early proteinuria of DM. The decrease in proteinuria and the correction of hyperlipidemia of DM by a FO-enriched diet may be beneficial in the long term not only for the development of diabetic glomerulopathy, but also for the accelerated atherosclerosis of DM.

Animals↗
PubMed1989

Hyperlipoproteinemia in spontaneously diabetic guinea pigs.

A colony of Hartley guinea pigs that exhibit hyperglycemia, glucosuria, and hypertriglyceridemia characteristic of human diabetes mellitus was developed. Initially, a group of guinea pigs that had normal serum glucose concentrations (less than or equal to 200 mg/dL of serum) at 3 to 4 weeks of age was obtained; however, in some of the animals progressively severe hyperglycemia (300 to 500 mg/dL of serum) and glucosuria (greater than 2 g of glucose/24 h) occurred as the animals matured. In addition, the animals exhibiting hyperglycemia and glucosuria had plasma insulin concentrations that were similar to those animals that were not hyperglycemic. The diabetic animals were found to be hypertriglyceridemic, with plasma triglyceride levels of 140 to 290 mg/dL at four months of age. Nondiabetic animals (plasma glucose concentration of less than or equal to 200 mg/dL and no glucosuria) had plasma triglyceride concentrations between 37 and 76 mg/dL. Lipoprotein analysis of plasma from nondiabetic and diabetic animals indicated that the diabetics had a fourfold increase in VLDL triglyceride and protein concentrations. The VLDL had an abnormal apolipoprotein composition and had reduced levels of apoprotein-E. The progeny from the mating of diabetic males and females also exhibited the diabetic trait, suggesting that the origin of the disease is genetic. This colony of guinea pigs is being further investigated as a suitable model for the study of the hyperlipoproteinemia of human noninsulin-dependent diabetes mellitus.

Animals↗
PubMed1989

Listeriosis: a community problem?

Three epidemiologically distinct cases of listeriosis, one perinatal and two adult, presented in hospital over a three day period. Clinical signs were non-specific with pyrexia and respiratory distress. Diagnosis in all three was made by blood cultures. Such cases reflect the general increase in reporting of listeriosis and suggest that the condition is increasing in incidence in the community, most likely due to food contamination. Raw vegetables, milk, soft cheeses, pre-cooked and inadequately cooked meats have all been implicated. Regular public health inspection of foods and food storage facilities with increased public awareness of the hazards of inadequate cooking and storage of food are the most effective means of preventing listeriosis and its potentially disastrous consequences especially for pregnant women and immunosuppressed patients.

Adult↗
PubMed1986

Contraction and relaxation of cultured mesangial cells on a silicone rubber surface.

Glomerular mesangial cells (MC) in culture are believed to contract or relax in response to agents such as angiotensin II and cyclic AMP. However, cells grown on glass or plastic surfaces are limited in their response to vasoactive agents because of the rigid surfaces to which they adhere; thus, interpretation of a change in shape as contraction, relaxation, or detachment is difficult. We have grown MC on a flexible silicone rubber (dimethylpolysiloxane) substrate (DMPS), and studied with sequential photographs several models of cell contraction, relaxation, and detachment. When the cells contracted, the DMPS became wrinkled; when the cells relaxed, the DMPS lost wrinkles. In contrast, if the cells detached, the sheet lost wrinkles as the cells became smaller and rounder. Angiotensin II (5 X 10(-7) M), and calcium ionophore A23187 (2 X 10(-6) M) increased wrinkles in more than 30% of cells at 22 degrees C and more than 40% of the cells at 36 degrees C. The earliest effect was visible within five to 10 minutes at 22 degrees C and within one minute at 36 degrees C and increased until 40 minutes; thereafter, the cells relaxed and wrinkles were reduced. 10(-1) M Na azide prevented the increase in wrinkles produced by angiotensin II. Seventy-two percent of the angiotensin II-treated cells whose margins could be seen in their entirety, and 78% of the calcium ionophore-treated cells showed a reduction in surface area at a time when new wrinkles were appearing or wrinkles were increasing in size. Dibutyryl cyclic AMP, a known smooth muscle relaxant, produced a decrease or loss of wrinkles in 90% of the cells, and an accompanying increase in surface area. Untreated control cells, observed in conjunction with the above series, showed little change in wrinkles. Ten percent DMSO, an actin-translocating agent, produced a reversible disappearance of wrinkles. These models of contraction and relaxation could be distinguished from cell detachment; EDTA, for example, in the presence of zero calcium, diminished both cell size and wrinkles, with an accompanying lifting of cells from the surface. Similar results were obtained with cytochalasin B and chlorpromazine. Thus, the silicone rubber system accurately reflects the contraction, relaxation and detachment of cultured mesangial cells in response to a variety of agents.

Angiotensin II↗
PubMed1976

Eosinophil-enriched inflammatory response to schistosomula in the skin of mice immune to Schistosoma mansoni.

Exposure of the mouse skin to Schistosoma mansoni cercariae gives rise to acute, exudative inflammation in both normal and immune mice, but the immune response is anamnestically accelerated and is oesinophil-enriched, thereby enhancing opportunities for tegumental contact of schistosomula with host leukocytes, particularly with eosinophils. Many of the inflammatory changes occurring within the first 48 hours after exposure are due to cercarial products, e.g., "penetration tracts," but some remain demonstrable when schistosomula metamorphosed in vitro are injected intradermally and are therefore directed against the schistosomula themselves, such as the leukocyte "streaming patterns" seen in their pathways. In contrast to earlier observations in primates, cellular responses to schistosomula in the mouse lung 4 days after penetration are minimal in either normal or immune mice. Thus, immune cellular responses to schistosomula in mice are limited to an early time period after cercarial penetration and are morphologically suggestive of an antibody-mediated response rather than of delayed hypersensitivity. Our observations complement earlier evidence suggesting that antibody-mediated host leukocyte contact with schistosomula initiates the killing of challenge parasites in immune mice, with the eosinophil probably playing a crucial role.

Animals↗
PubMedDate not supplied

Case report: combined hand access with laparoscopic pneumoperitoneum in intraperitoneal adhesiolysis.

Previous abdominal surgery is one of the relative contraindications to safe induction of pneumoperitoneum with a Veress needle. Similarly visual inspection with a telescope may be limited and instrumental manipulation difficult. The manual ability to distract bowel loops and finger dissect greatly facilitates adhesiolysis and this is lost with conventional laparoscopy. A novel hand-access port is described which combines manual tactile ability with minimally invasive laparoscopic adhesiolysis.

Aged↗