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N T Richards

Publications and source records attributed to N T Richards.

At least 19 recordsLinked to original sources
PubMed1994

Effect of flosequinan on human small subcutaneous arteries.

We have investigated the effect of the novel hypotensive agent, flosequinan, on human small artery constrictor function. Concentration-dependent tension development to both noradrenaline and K+ was reduced in the presence of flosequinan. Arteries pre-contracted with noradrenaline demonstrated a greater concentration-dependent relaxation to flosequinan than did those pre-contracted with K+. Flosequinan depressed the sensitivity to extracellular Ca2+ of arteries pre-contracted with noradrenaline, but this effect was less marked in arteries pre-contracted with K+. These data support previous studies which suggest that flosequinan may affect receptor-mediated contraction by reducing Ca2+ sensitivity.

Adult↗
PubMed1994

Anti-idiotypic activity against anti-myeloperoxidase antibodies in pooled human immunoglobulin.

We investigated the ability of six different pooled human immunoglobulin (PHIG) preparations to inhibit the binding of anti-myeloperoxidase (MPO) antibodies to MPO. All six PHIG preparations inhibited the binding of anti-MPO antibodies from six sera to MPO in a concentration-dependent manner in the concentration range 0.016-10 mg/ml. There was considerable variation in the ability of each PHIG preparation to inhibit the binding of anti-MPO antibody in a given serum. Further differences were seen in the ability of a given PHIG to inhibit anti-MPO binding in different sera. F(ab')2 fragments from two PHIG preparations also inhibited in a concentration-dependent manner anti-MPO binding to MPO in all six sera in the concentration range 0.002-2.65 mg/ml, with a maximum inhibition of 42%. Little inhibition was seen with F(ab')2 of normal human IgG from individual donors (1.8-12.2% at the maximum concentration of 2 mg/ml). F(ab')2 fragments from three anti-MPO containing sera and two affinity-purified anti-MPO antibodies were eluted by affinity chromatography from Sepharose-bound PHIG F(ab')2 and showed anti-MPO antibody activity. We have shown that PHIG and F(ab')2 fragments of PHIG inhibit anti-MPO binding to MPO, and further that F(ab')2 fragments of PHIG bind to F(ab')2 fragments of anti-MPO antibodies. These observations indicate binding between the variable regions of PHIG and the antigen binding site of anti-MPO antibodies, and are consistent with an anti-idiotypic reaction. The variability seen in the inhibitory effect of the different PHIG preparations in anti-MPO-positive sera implies differences in their anti-idiotype content, while the variability of the inhibitory effect of a particular PHIG preparation between different sera suggests heterogeneity in the idiotypic repertoire of anti-MPO antibodies. Such variations in the inhibitory effect of different PHIG preparations on antibody binding may be an important determinant of their therapeutic effect.

Animals↗
PubMed1994

Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression and function on cultured human glomerular epithelial cells.

Glomerular epithelial cells are involved in extracapillary inflammation (crescents) but the mechanisms of this extracapillary accumulation of macrophages, epithelial cells and occasional lymphocytes are unknown. Human glomerular parietal epithelial cells express ICAM-1 and VCAM-1 on immunohistological stains of renal biopsies. We studied the expression of these cell adhesion molecules on cultured human glomerular epithelial cells (HGEC), their regulation by pro-inflammatory cytokines, and their role in mediating the adhesion of concanavalin A (Con A)-activated peripheral blood mononuclear cells. Human glomerular epithelial cells in culture constitutively express ICAM-1 and VCAM-1. The expression of ICAM-1 was not significantly altered by tumour necrosis factor-alpha (TNF-alpha) (P = 0.32), IL-1 beta (P = 0.24), interferon-gamma (IFN-gamma) (P = 0.66) or IL-4 (P = 0.85). VCAM-1 expression was increased by all four cytokines, but only significantly so by IL-4 (P = 0.0001). Con A-stimulated, monocyte-depleted peripheral blood lymphocytes bound to human glomerular epithelial cells, median 28.9% (range 14.5-37.9%). This adherence was significantly inhibited by anti-ICAM-1 (P = 0.03) and anti-LFA-1 (P = 0.02), but not by anti-VCAM-1 (P = 0.13) or by antibody to von Willebrand factor (P = NS). The interaction between ICAM-1 on HGEC and LFA-1 on mononuclear cells may be important in the pathogenesis of extracapillary inflammation in glomerulonephritis.

Cell Adhesion↗
PubMed1994

Interdependence of contractile responses of rat small mesenteric arteries on nitric oxide and cyclo-oxygenase and lipoxygenase products of arachidonic acid.

1. We have examined the effects of nitric oxide inhibition, indomethacin and the dual lipoxygenase/cyclo-oxygenase inhibitor, 3-amino-1-[m-(trifluoromethyl)-phenyl]-2-pyrazoline (BW755C), on the responses of small mesenteric arteries of Wistar rats, with and without endothelium, to noradrenaline, potassium chloride, endothelin-1, acetylcholine and sodium nitroprusside. 2. Noradrenaline, potassium chloride and endothelin-1 caused concentration-dependent contraction of small mesenteric arteries. Indomethacin (14 microM) attenuated the contractile response to both noradrenaline and potassium chloride. The inhibitory action of indomethacin persisted in vessels treated with CHAPS. 3. Acetylcholine produced concentration-dependent relaxation in these vessels. Indomethacin (14 microM) had no significant effect on the acetylcholine concentration-response relationship. 4. NG-nitro-L-arginine methyl ester (L-NAME, 100 microM) potentiated the contractile response to both noradrenaline and potassium chloride and inhibited acetylcholine-induced relaxation. Indomethacin attenuated the effects of L-NAME. 5. BW755C inhibited the contractile response to noradrenaline and potassium chloride but not to endothelin-1. The inhibitory effects of BW755C persisted in the presence of indomethacin and in vessels treated with CHAPS. 6. BW755C enhanced endothelium-dependent relaxation, as assessed by the response to acetylcholine. In the presence of indomethacin, BW755C produced a shift to the right of the concentration-response curve to acetylcholine. 7. Inhibition of nitric oxide synthase with L-NAME, reversed the inhibitory effect of BW755C on noradrenaline- and potassium-induced contraction. L-NAME and BW755C in combination resulted in a shift to the right of the concentration-response curve to acetylcholine. 8. Sodium nitroprusside produced concentration-dependent relaxation of the vessels. Endothelium removal reduced the maximum relaxation to nitroprusside. BW755C did not alter the response to sodium nitroprusside in vessels with or without endothelium.9 .These data support the existence of two vasoconstrictor products of arachidonic acid released during contraction of small mesenteric arteries with noradrenaline and potassium chloride: a cyclo-oxygenase product and a lipoxygenase product both of which appear to be largely endothelium-independent.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1994

Relative roles of nitric oxide and cyclo-oxygenase and lipoxygenase products of arachidonic acid in the contractile responses of rat renal arcuate arteries.

1. We have examined the effects of inhibition of nitric oxide synthase, cyclo-oxygenase and lipoxygenase on the responses of renal arcuate arteries of Wistar rats, with and without endothelium, to noradrenaline, potassium chloride, endothelin-1, acetylcholine and sodium nitroprusside. 2. Noradrenaline, potassium chloride and endothelin-1 caused concentration-dependent contraction of the vessels. Indomethacin (14 microM) attenuated the contractile response to noradrenaline and to potassium chloride. The inhibitory effect of indomethacin persisted following endothelial removal. 3. Acetylcholine produced concentration-dependent relaxation of the vessels which was potentiated by indomethacin (14 microM). 4. NG-nitro-L-arginine methyl ester (L-NAME, 100 microM) did not affect the contractile response to either noradrenaline or potassium chloride but abolished relaxation to acetylcholine. In addition, L-NAME abolished the affects of indomethacin on acetylcholine-induced relaxation and noradrenaline- and potassium chloride-induced contraction. 5. BWC755C attenuated noradrenaline and potassium chloride-induced contraction. This effect persisted in the presence of indomethacin. 6. In vessels pretreated with CHAPS, BW755C inhibited both noradrenaline and potassium chloride-induced contraction. In these vessels BW755C had no additional inhibitory effect to indomethacin on noradrenaline- and potassium-induced contraction. 7. Inhibition of nitric oxide synthase with L-NAME (100 microM) attenuated the effect of BW755C on noradrenaline- and potassium-induced contraction. 8. BW755C alone did not affect endothelium-dependent relaxation as assessed by the response to acetylcholine. However, in the presence of indomethacin, BW755C inhibited acetylcholine-induced relaxation. 9. BW755C did not affect endothelium-independent relaxation as assessed by the response to sodium nitroprusside in vessels with or without endothelium. 10. These data support the existence of two vasoconstrictor products of arachidonic acid released during contraction of renal arcuate arteries with noradrenaline and potassium chloride. A cyclooxygenase product which appears to be endothelium-independent and the other an endothelium dependent lipoxygenase product.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1994

Circulating soluble adhesion molecules in systemic vasculitis.

The plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1), E-selectin (sE-selectin), and vascular cell adhesion molecule-1 (sVCAM-1), might reflect endothelial activation and injury and would therefore be useful markers of disease activity in vasculitis. To investigate this we measured the levels of sICAM-1, sE-selectin, and sVCAM-1 by two-site ELISAs in the plasma of patients with (a) active vasculitis (n = 16), (b) vasculitis in remission (n = 15), (c) chronic renal failure (CRF) (n = 10), and (d) normal healthy controls (n = 10). Plasma sICAM-1 levels were significantly higher in patients with active vasculitis, 323 ng/ml (193-607) compared with patients with inactive vasculitis, 199 ng/ml (131-297); P = 0.0006 and healthy controls, 188 ng/ml (138-259); P = 0.0002. Plasma sE-selectin levels were also significantly higher in the patients with active vasculitis, 45 ng/ml (15-65) compared with patients with inactive vasculitis, 25 ng/ml (15-55); P = 0.027 but not when compared with healthy controls, 35 ng/ml (20-55); P = 0.16. There was no difference in plasma sVCAM-1 levels between patients with active vasculitis, OD 0.56 (0.45-0.85) and inactive disease, OD 0.58 (0.47-0.79) (P = 0.12) or with healthy controls OD 0.49 (0.42-0.68) (P = 0.48). There were no significant differences between the plasma levels of any of the soluble adhesion molecules between patients with active vasculitis and patients with chronic failure.(ABSTRACT TRUNCATED AT 250 WORDS)

C-Reactive Protein↗
PubMed1994

Knowledge of renal histology alters patient management in over 40% of cases.

There is great debate as to whether the benefit gained from the knowledge of renal histology outweighs the risk to the patient from the biopsy procedure. We conducted a prospective study of 276 native renal biopsies performed on 266 patients from a single centre in 1991 to assess the effect of the knowledge of renal histology on patient management. Biopsies were performed under ultrasound guidance using the Trucut biopsy needle. The indications for biopsy were: non-nephrotic proteinuria alone (25), haematuria and proteinuria (28), nephrotic range proteinuria (28), acute renal failure (31), haematuria alone (36), and chronic renal failure (128). Two hundred and sixty-three biopsies were successful. The mean number of glomeruli obtained was 23, range 0-115. Eight patients developed macroscopic haematuria of which two required blood transfusion. The result of the biopsy altered management in 24/28 (86%) of cases of nephrotic range proteinuria, 22/31 (71%) of cases of acute renal failure, 58/128 (45%) of cases of chronic renal failure, 9/28 (32%) of cases with haematuria and proteinuria, 3/25 (12%) of cases with non-nephrotic proteinuria alone, and 1/36 (3%) of cases with haematuria alone. management was altered in 42% of cases overall. These data suggest that knowledge of renal histology is essential in the management of patients with renal disease.

Adolescent↗
PubMed1993

Increased prevalence of dialysis-dependent renal failure in ethnic minorities in the west Midlands.

A total of 1038 adult patients with dialysis-dependent renal failure were treated at this centre between 1981 and 1991. Data on racial origin and primary renal diagnosis have been analysed in order to determine the prevalence of end-stage renal failure (ESRF) and its causes. Compared with Caucasians there was a greater proportion of Asians (P < 0.001) and Blacks (P < 0.001) with ESRF. The relative risk of ESRF in Asians compared with Caucasians was 1.76 (95% CI 1.46-2.10) and for Blacks 1.76 (95% CI 1.39-2.2). Hypertension/renal vascular disease and systemic lupus erythematosus were more frequent causes of ESRF in Blacks than in Caucasians (P < 0.005). Hypertension/vascular disease and tuberculosis were more frequent causes of ESRF in Asians than Caucasians (P < 0.005) respectively. Diabetes mellitus appeared to be more common as a cause of ESRF in Blacks than Asians or Caucasians (0.1 > P > 0.05). Adult polycystic disease was significantly less common in Asians compared to Caucasians and Blacks (P < 0.05). The prevalence of ESRF in Asians and Blacks in the West Midlands appears to be greater than that of Caucasians, mostly as a consequence of hypertension/vascular disease and to a lesser extent of systemic lupus erythematosus in Blacks and of tuberculosis in Asians. If these data are confirmed by prospective study then they have implications for service provision.

Adolescent↗
PubMed1993

Different clinicopathological types of segmental sclerosing glomerular lesions in adults.

Renal biopsies and kidneys from 111 adult patients with segmental sclerosing glomerular lesions were put into different morphological groups by pathologists unaware of clinical findings. 'Overload changes' (n = 11) were large glomeruli with hilar lesions. Ten of these patients had reduced renal mass. In the 'glomerular tip lesion' (n = 10) there were changes at the tubular origin in otherwise normal glomeruli. All patients in this group had the nephrotic syndrome, completely responsive to steroids. 'Mesangial hypercellularity with diffuse segmental changes at the glomerular tip', corresponding to 'early classical focal segmental glomerulosclerosis' (n = 18), differed from the glomerular tip lesion in that glomeruli were larger and hypercellular. Most patients with this classification had the nephrotic syndrome, several were given additional immunosuppression, and less than half had complete remission. 'Diffuse multiple segmental lesions', corresponding to 'late classical focal segmental glomerulosclerosis' (n = 16), presented usually with the nephrotic syndrome, and most of these patients had no response to immunosuppression. Unlike most other groups, in 'focal segmental sclerosing lesions' (n = 56) there were genuinely focal lesions, not in every glomerulus. Most patients had asymptomatic proteinuria. Pathological study is able to classify segmental lesions that would often be grouped as 'focal segmental glomerulosclerosis' into types with different pathogenesis, clinical findings, appropriate treatment, response to treatment, and prognosis.

Adolescent↗
PubMed1992

Pigeons and peritonitis?

We report an outbreak of fungal peritonitis due to Candida parapsilosis in 12 patients undergoing chronic ambulatory peritoneal dialysis (CAPD). All 12 patients were treated by removal of the CAPD catheter together with systemic antifungal therapy. There were no peritonitis-related deaths. Four patients were successfully returned to CAPD at a later date. Microbiological investigation during the outbreak demonstrated colonization of various areas of the CAPD Unit and medical ward with the organism. C. parapsilosis was also isolated from pigeon guano obtained from window-sills. The number of cases of peritonitis due to this organism decreased markedly after bird-proof netting was installed. We believe that this is the first report of an outbreak of CAPD peritonitis due to faecal carriage of C. parapsilosis by pigeons.

Adult↗
PubMed1992

Increased prevalence of renal biopsy findings other than diabetic glomerulopathy in type II diabetes mellitus.

It is a widely held view that when a patient with type I diabetes mellitus and diabetic retinopathy or neuropathy develops renal impairment the renal lesion will be diabetic glomerulonephropathy. This has been extrapolated to apply to type II diabetes. We have performed a retrospective study of the clinical data of patients with diabetes mellitus who have had a renal biopsy between November 1980 and December 1990. Seventy-one patients were biopsied, data were available on 68. Nineteen of 22 type I diabetics had diabetic glomerulopathy, two had diabetic glomerulopathy in addition to another lesion only one patient did not have diabetic glomerulopathy. Twenty-three of 46 type II diabetics had diabetic glomerulopathy alone 22 having an alternative diagnosis. Eight further patients were identified who were not known to be diabetic at the time of renal biopsy, but whose biopsies revealed diabetic glomerulopathy. These data suggest that patients with type II diabetes and renal impairment should have a renal biopsy as part of their investigation.

Adult↗
PubMed1991

Low-concentration ouabain does not inhibit noradrenaline-induced contraction of human resistance arteries.

1. Using a Mulvany-Halpern myograph to measure changes in isometric tension, we have investigated the effect of ouabain on noradrenaline-induced contraction of human subcutaneous resistance arteries. 2. Low concentrations of ouabain (10 nmol/l or less) were shown not to alter vascular smooth muscle contractility or sensitivity to noradrenaline. 3. In contrast, higher concentrations of ouabain (100 nmol/l or more) were found to depress vascular smooth muscle contractility and to reduce the sensitivity of the noradrenaline concentration-response relationship. 4. These findings may have implications regarding the presence of an endogenous inhibitor of the sodium pump in essential hypertension and in pregnancy-associated hypertension.

Arteries↗
PubMed1990

Acute haemodialysis during the Armenian earthquake disaster.

On the 7 December 1988 an earthquake struck a densely populated region in northern Armenia. Up to 50,000 people were killed and many thousands were seriously injured. At least 385 of these casualties developed acute renal failure secondary to crush syndrome and required dialysis. The Armenian renal unit at Yerevan, in common with units elsewhere, was already overstretched to cope with the dialysis requirements of their patients with chronic renal failure before the earthquake. Most of the patients requiring dialysis were transferred to other hospitals in the USSR but 120 patients remained in Yerevan, the majority at the regional renal unit, overwhelming the resources. We assisted by taking a team of dialysis personnel, equipped with portable haemodialysis machines, to Yerevan. We performed 57 haemodialysis sessions and treated 15 patients, 13 of whom ultimately survived. Valuable lessons were learnt about the medical management of disasters abroad.

Acute Kidney Injury↗
PubMed1990

Immunoglobulin heavy chain switch region gene polymorphisms in glomerulonephritis.

Much evidence suggests that primary IgA nephropathy (IgAN) and idiopathic membranous nephropathy (MN) are immune complex mediated diseases. Moreover, genetic factors may play an important role in their pathogenesis. Recently, restriction fragment length polymorphisms (RFLPs) of the immunoglobulin heavy chain genes have been described which appear to associate with glomerulonephritis. We have studied RFLPs of the switch region of the IgM (S mu) and IgA1 (S alpha 1) heavy chain in MN and IgAN. DNA obtained from British Caucasoids with IgAN (N = 75), MN (N = 43), and normal controls (N = 73), was digested with the restriction enzyme Sac1, and studied using Southern blot techniques and hybridization with a 32P labelled DNA probe homologous to S mu. This probe detects RFLPs at the S mu and S alpha 1 loci. The genotypic and allelic frequencies of the S mu and S alpha 1 alleles in IgAN and MN was similar to normal controls. Caucasoid subjects with IgAN from Northern and Southern Europe (Finland and Italy, respectively) were also studied to determine whether an ethnic variation in genetic susceptibility to IgAN exists. The frequency of the S mu and S alpha 1 alleles was similar between the patient groups and their respective local healthy controls. These results do not support the recent findings of an association with RFLPs of the S mu and S alpha 1 loci in IgAN and MN, and suggest that the immunoglobulin heavy chain switch region genes are not important in conferring disease susceptibility to IgAN or MN.

Blotting, Southern↗
PubMed1990

HLA DQ region gene polymorphism associated with primary IgA nephropathy.

IgA nephropathy (IgAN) has been associated with HLA-DR4. We have recently described two non-allelic Taq I DQ beta gene-associated fragments sized 2.0 kb (T2) and 6.0 kb (T6), which strongly associate with DR4. T2 represents a polymorphism of the DQ beta gene and has been redesignated DQw8 (10th International HLA Workshop). The origin of the T6 fragment has not been determined, but probably represents a polymorphism of either the DQ beta or DX beta gene. When present together T2 and T6 define a subgroup of DR4 subjects at high risk of developing autoimmune disease. We have, therefore, studied DQ beta gene polymorphisms in IgAN. The DR antigen distribution was similar in IgAN and normal controls. The T2+/T6+ phenotype was present in 49% patients with IgAN compared to 15% of controls [P less than 0.0001, chi 2 = 32.8, Cramer's V = 0.41; relative risk = 5.5 (range, 2.8-11.0)]. Seventy-two percent of DR4+ IgAN patients and 29% of DR4+ controls were T2+/T6+ (P = 0.007, chi 2 = 17.0). These findings confirm the hypothesis that disease susceptibility genes are important in IgAN, and suggest that the putative gene(s) are located within or near to the DQ subregion. Moreover, similar DQ beta gene associations have been found in IDDM and pemphigus vulgaris, pointing to a common immunogenetic mechanism predisposing to several autoimmune diseases.

Blotting, Southern↗