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H T Cook

Publications and source records attributed to H T Cook.

At least 55 records · Page 3Linked to original sources
PubMed1995

L-arginine depletion by arginase reduces nitric oxide production in endotoxic shock: an electron paramagnetic resonance study.

Nitric oxide (NO) synthesis was measured in the liver, lung, spleen and kidney of lipopolysaccharide-treated male rats using the nitric oxide spin trap, iron (II)-diethyldithiocarbamate (FeDETC2). Nitric oxide formation in vivo was determined by the increase in intensity of the characteristic triplet hyperfine EPR spectrum of [NO-FeDETC2]. Intravenous bovine liver arginase, at a dose which completely depleted circulating arginine, significantly reduced the formation of nitric oxide in these tissues. The general decrease in NO levels was confirmed by the decrease in plasma nitrite levels. These results directly demonstrate that NO formation in endotoxic shock depends on extracellular arginine; depletion of plasma arginine may be a useful therapeutic strategy.

Animals↗
PubMed1995

Enhanced expression of type 1 procollagen and transforming growth factor-beta in tuberculin induced delayed type hypersensitivity.

AIMS: Tissue fibrosis is a common and serious consequence of chronic inflammation. The mechanism linking these two processes is poorly understood. The present study has utilised a human in vivo model of a delayed type hypersensitivity (DTH) reaction, the tuberculin Heaf reaction, induced by intradermal tuberculin in BCG immunised subjects, to dissect the relation between these two processes. METHODS: Punch skin biopsy specimens were obtained on day 5, day 13 and six to 16 weeks following the tuberculin Heaf test in 18 subjects with grade 3 or 4 responses. Skin biopsy specimens from six subjects served as controls. The specimens were examined using immunohistochemical staining for type 1 procollagen and transforming growth factor-beta (TGF-beta), as well as in situ hybridisation for type 1 procollagen messenger RNA (mRNA). RESULTS: Immunohistochemical analysis revealed increased deposition of TGF-beta in tissue matrix in the biopsy specimens obtained on day 5 following the tuberculin Heaf test. There was also extensive type 1 procollagen staining in the biopsy specimens obtained as early as day 5. Procollagen-1 staining was maximal on day 13, and was present in biopsy specimens from tuberculin Heaf test sites up to eight weeks after the tuberculin inoculation. The type 1 procollagen was localised within cells surrounding areas of inflammatory infiltrate and in perivascular tissues. The presence of new collagen formation was confirmed by in situ hybridisation using oligonucleotide probes for type 1 procollagen mRNA in cells in sections from biopsy specimens obtained on day 13. CONCLUSIONS: These data from a human in vivo model of a DTH response indicate that the immune response is intimately associated with an increase in the production of growth factors and the initiation of a fibrotic response.

Base Sequence↗
PubMed1994

True malignant mixed tumour of a minor salivary gland.

True malignant mixed tumours (carcinosarcomas) of salivary gland origin are rare and not widely recognized lesions. These tumours account for approximately 0.2 per cent of all malignancies of the major salivary glands (Stephen et al., 1986). They usually occur in pre-existing pleomorphic adenomas of major salivary glands and have an aggressive and often rapidly fatal progression. We report a case of carcinosarcoma in a minor salivary gland of the upper lip. Its management and the use of immunocytochemical stains to demonstrate the separate epithelial and connective issue components are discussed.

Adult↗
PubMed1994

Cellular localization of inducible nitric oxide synthase in experimental endotoxic shock in the rat.

1. Endotoxin induces a shock-like syndrome with increased nitric oxide synthesis. To clarify the cellular source of NO in endotoxic shock we used immunohistochemistry and in situ hybridization to localize inducible NO synthase in rats given lipopolysaccharide or Corynebacterium parvum and lipopolysaccharide. Immunohistochemistry was carried out with an antibody raised against a synthetic peptide of mouse macrophage NO synthase. In situ hybridization was performed with 35S-labelled oligonucleotide probes corresponding to cDNA sequences common to mouse macrophage inducible NO synthase and rat vascular smooth inducible NO synthase. Monocytes and macrophages were identified by immunohistochemistry with the mouse monoclonal antibody ED1. 2. After lipopolysaccharide alone, the major site of NO synthase induction was monocytes and macrophages in multiple organs, principally liver and spleen. Bronchial, bile duct, intestinal and bladder epithelium and some hepatocytes also expressed inducible NO synthase. Expression peaked at 5 h and had returned to normal by 12 h except in spleen. 3. After priming with C. parvum, lipopolysaccharide led to a similar distribution of inducible NO synthase as lipopolysaccharide alone, but in addition there was more prominent hepatocyte staining, staining in macrophage granulomas in the liver and inducible NO synthase was present in some endothelial cells in the aorta. 4. These findings provide a direct demonstration of the cellular localization of inducible NO synthase after lipopolysaccharide.

Amino Acid Oxidoreductases↗
PubMed1994

Expression of the gene for inducible nitric oxide synthase in experimental glomerulonephritis in the rat.

Nitrite, a stable product of nitric oxide (NO), is synthesized in vitro by glomeruli in experimental glomerulonephritis. We have now studied the expression of the gene for inducible NO synthase (iNOS) in accelerated nephrotoxic nephritis (NTN). The purpose of the study was to confirm in vivo induction of iNOS in this model of immune complex disease, and to relate the onset of induction and the level of expression to pathogenic events in the model. Glomeruli from rats with NTN were isolated at 6 h, 24 h and 2, 4 and 7 days and total RNA extracted. RNA (10 micrograms) was reverse transcribed and polymerase chain reaction (PCR) was performed with primers homologous to rat vascular smooth muscle iNOS and rat beta actin. A 222-base PCR product corresponding to iNOS mRNA was present in all experimental animals. iNOS expression was also found in activated macrophages, neutrophils and IL-1-stimulated but not unstimulated mesangial cells. Quantitative competitive PCR was carried out on glomerular samples using a 514-bp mutant of a 735-bp PCR product. iNOS expression was present at low levels in normal glomeruli and was markedly enhanced at 6 h after the induction of glomerulonephritis and peaked at 24 h. Increased iNOS expression persisted to day 7. beta actin mRNA levels were similar in all glomerular specimens. This study demonstrates that there is in vivo induction of iNOS in immune complex glomerulonephritis, corresponding to the generation of nitrite we have previously reported. iNOS gene expression is detectable within 6 h of induction of NTN, indicating the onset of gene transcription is closely related to the initial formation of immune complexes.

Amino Acid Oxidoreductases↗
PubMed1994

Type 1 procollagen as a marker of severity of scarring after sternotomy: effects of topical corticosteroids.

AIMS: To determine whether the abundance of newly formed collagen in healing surgical wounds correlated with scar severity, and whether topical application of steroid cream reduced new collagen formation in patients who have undergone median sternotomy. METHODS: Thirty three patients six weeks after sternotomy, and 12 controls were studied. Scars were photographed, and biopsy specimens from scars at sites treated or untreated with topical corticosteroids (clobetasol proprionate 0.5%) were examined using immunohistochemical staining for type 1 procollagen (PCP 1) and transforming growth factor beta (TGF-beta), and in situ hybridisation for type 1 procollagen messenger RNA (mRNA). RESULTS: The degree of hypertrophy of the scar and the abundance of PCP 1 immunostaining were ranked independently, blind, and a correlation between these two variables was observed (r = 0.604, p < 0.001). The PCP 1 immunostaining was accompanied by a great abundance of PCP 1 mRNA and only a slight increase in TGF-beta immunostaining, when compared with normal skin or mature scars. Following the application of topical corticosteroids, for either 48 hours or twice daily for seven days, there was no reduction in PCP 1 immunostaining nor the abundance of PCP 1 mRNA. CONCLUSIONS: These data suggest that the extent of new collagen formation as assessed by PCP 1 immunohistochemistry may be a useful marker of the exuberance of the scarring process following sternotomy, and that topical corticosteroids are ineffective in reducing this component of the fibrotic response.

Base Sequence↗
PubMed1994

Arginine metabolism in experimental glomerulonephritis: interaction between nitric oxide synthase and arginase.

L-Arginine is metabolized by two pathways: 1) by nitric oxide synthase (NOS) to nitric oxide (NO) and 2) by arginase forming urea and L-ornithine. Inflammatory responses may involve a balance between the pathways, as NO is cytotoxic and vasodilatory and L-ornithine is a promoter of cell proliferation and matrix synthesis. In experimental glomerulonephritis we have previously shown that NOS is activated in nephritic glomeruli. We have now examined both pathways of L-arginine metabolism to study competition for L-arginine, temporal variation, and the sources of NOS and arginase. Acute in situ glomerulonephritis was induced in rats, and glomeruli were studied at 1, 4, and 7 days. Both NOS and arginase activities were present. There was temporal variation: NOS activity was highest on day 1 and arginase activity on day 4; both declined by day 7. Competition between the pathways was demonstrated by increased urea synthesis in the presence of NG-monomethyl-L-arginine, an inhibitor of NOS. Measurement of NOS and arginase activities in macrophages isolated from nephritic glomeruli showed that these cells were a major source of glomerular NOS but not arginase activity. In contrast, high arginase activity but low NO production was identified in cultured rat glomerular mesangial cells. These studies show differential temporal variation in expression of NOS and arginase pathways of arginine metabolism in experimental glomerulonephritis. We have found two factors that may contribute to this: 1) competition for substrate L-arginine between the two pathways and 2) different cellular sources. We hypothesize that the balance between these pathways is a mechanism regulating injury, hemodynamics, and mesangial cell proliferation.

Amino Acid Oxidoreductases↗
PubMed1994

Interleukin-1 beta gene expression in experimental glomerulonephritis in the rat: an in-situ hybridization study.

To investigate the role of interleukin-1 beta (IL-1 beta) in glomerulonephritis we studied the presence of IL-1 beta by in-situ hybridization in in-situ immune complex glomerulonephritis in the rat. Glomerulonephritis was induced in preimmunized rats by unilateral renal perfusion with cationized human IgG. In-situ hybridization was performed on frozen sections with a battery of four 30mer oligonucleotide DNA probes 3' end labelled with 35S-dATP. IL-1 beta mRNA was detectable in nephritic glomeruli at 6 and 24 hours after induction of glomerulonephritis. Signal was maximal at 48 hours and markedly reduced by 4 days. The peak of IL-1 beta transcription coincided with the major monocyte influx into glomeruli consistent with a role for IL-1 beta as a mediator of glomerular hypercellularity.

Animals↗
PubMed1992

Arginase is a major pathway of L-arginine metabolism in nephritic glomeruli.

L-arginine can be metabolized to nitric oxide (NO) by nitric oxide synthase (NOS) and to urea and L-ornithine by arginase. Competition between these pathways for L-arginine in inflammatory sites has been suggested. In experimental glomerulonephritis glomeruli produce nitrite; a major source is macrophages. We hypothesized that arginase is present in glomeruli and may compete for substrate with NOS in glomerulonephritis. Therefore we examined both pathways in isolated nephritic glomeruli and peritoneal macrophages. Arginase activity was present in glomeruli, increased by > 500% in nephritic glomeruli compared to controls, and was predominant over NOS. Activity increased with L-NMMA (a NOS inhibitor), but this trend did not reach statistical significance. In macrophages both pathways were present; NOS predominated basally but this was reversed by L-NMMA. In contrast with glomeruli macrophage arginase activity increased after LPS stimulation. Levels of macrophage arginase activity could not account for activity in nephritic glomeruli, suggesting another source of arginase. This is the first demonstration of high arginase activity of nephritic glomeruli. Competition between arginase and NOS pathways suggests a regulatory mechanism of L-arginine metabolism within the glomerulus, with implications for the pathogenesis of injury and scarring in glomerulonephritis.

Amino Acid Oxidoreductases↗
PubMed1991

Glomerular nitrite synthesis in in situ immune complex glomerulonephritis in the rat.

Nitrite (NO2-) is the major end product of nitric oxide (NO) production in cell culture. The authors have examined nitrite production by glomeruli in in situ immune complex glomerulonephritis in the rat. Glomerulonephritis was induced by unilateral renal perfusion of cationized human gamma G immunoglobulin (IgG) in preimmunized rats. NO2- was measured in culture supernatants of isolated glomeruli after 48 hours. NO2- was produced by nephritic glomeruli with a maximum 4 days after induction of glomerulonephritis (24.4 +/- 11.4 pmol/glomerulus/48 hours). Production was increased by lipopolysaccharide (LPS; 1 micrograms/ml) (54 +/- 4.9 pmol/glomerulus; P less than 0.001). NO2- production was inhibited by the nitric oxide synthase inhibitor NG-monomethyl-L-arginine demonstrating synthesis through NO. Dexamethasone (10(-7) mol/l [molar]) reduced LPS-stimulated production by peritoneal macrophages and nephritic glomeruli (P less than 0.01). Macrophages isolated from nephritic glomeruli produced NO2- (4.9 +/- 0.6 nmols/10(5) cells). The production of NO by nephritic glomeruli has implications for mechanisms of glomerular injury and glomerular hemodynamics. The effect of dexamethasone may explain in part the ameliorative effect of steroids in glomerulonephritis.

Animals↗
PubMed1990

Prostaglandin E1 suppresses macrophage infiltration and ameliorates injury in an experimental model of macrophage-dependent glomerulonephritis.

Prostaglandin E1 (PGE1) suppresses macrophage infiltration and ameliorates injury in an experimental model of macrophage dependent glomerulonephritis. Macrophages are mediators of glomerular injury in models of proliferative glomerulonephritis. We have recently shown that macrophages in glomerulonephritis have low prostaglandin E2 (PGE) generation, and other evidence implicates eicosanoids as regulators of macrophage activation. Here we have studied in rats the effect of 15(s)-15-methyl PGE1 (M-PGE1) on accelerated nephrotoxic nephritis, a model of acute macrophage-dependent glomerular injury. M-PGE1 ameliorated proteinuria (day 4; 61 +/- 13 mg/24 h, n = 9; vehicle treated, 164 +/- 17 mg/24 h, n = 11; P less than 0.002) and glomerular hypercellularity; quantification of infiltrating macrophages by isolating glomerular cells showed reduction in the numbers of macrophages (44 +/- 9/glomerulus; vehicle treated, 119 +/- 15/glomerulus; P less than 0.02) with inhibition of Ia antigen expression on infiltrating macrophages (8 +/- 5%; vehicle treated 25 +/- 4% P less than 0.05). Glomerular binding of nephrotoxic globulin and levels of autologous antibodies were not affected by M-PGE1. Thus the mechanism of suppression involves inhibition of macrophage accumulation and activation. M-PGE1 administered to normal rats did not affect numbers of resident leucocytes (12.6 +/- 1.5/glomerulus; vehicle treated, 13.2 +/- 1.3/glomerulus) or alter Ia antigen expression (4.1 +/- 0.2 Ia + cells/glomerulus; vehicle treated, 3.9 +/- 0.6/glomerulus). This study suggests a therapeutic role for PGE1 in this type of glomerulonephritis, and has implications for the pathophysiology of macrophage-mediated inflammation.

Alprostadil↗
PubMed1989

Functional characteristics of macrophages in glomerulonephritis in the rat. O2- generation, MHC class II expression, and eicosanoid synthesis.

Macrophage infiltration is important in the pathogenesis of acute proliferative glomerulonephritis (gn). The state of activation of macrophages during gn may be central to their role in injury. To study this, a method for extracting macrophages from nephritic glomeruli in active in situ gn was developed. MHC Class II (Ia) antigen expression, superoxide (O2-) generation, and eicosanoid synthesis were compared with thioglycollate elicited peritoneal macrophages (TEM). At the height of inflammation there were 407 +/- 83 macrophages/glomerulus. Compared with TEM, Ia expression, and in vitro production of O2- were enhanced. Synthesis of prostaglandin E2 was greatly reduced (day 6 gn, 62 +/- 10 ng/mg; TEM 663 +/- 128 ng/mg cell protein). Thromboxane synthesis was relatively conserved (day 6 gn, 109 +/- 28 ng/mg; TEM 201 +/- 53 ng/mg). Leukotriene B4 (LTB4) was undetectable (day 6 gn, less than 13 ng/mg; TEM 119 +/- 56 ng/mg). This large influx of activated macrophages in glomeruli may be fundamental to pathogenesis of glomerular inflammation.

Animals↗
PubMed1988

Plasmacytoma of the ovary.

A plasmacytoma of the ovary in a 63-year-old is described. It was associated with an IgA K paraprotein. Myelomatosis developed 2 years after excision of the tumor.

Female↗
PubMed1988

Renin in mesoblastic nephroma: an immunohistochemical study.

Congenital mesoblastic nephroma (CMN) is the most common renal tumor of early infancy. It is usually evident at birth as an abdominal mass and is composed of spindle-shaped cells resembling smooth muscle cells and fibroblasts. There is macroscopic and microscopic infiltration of the surrounding kidney and entrapped tubules and glomeruli are common at the edge of the tumor. In this report, we describe a case of CMN associated with hyperreninaemia and hypertension. We examined the tumor from this case and 11 other cases for the presence of renin using a polyclonal antibody to human kidney renin. Hypertension was present in three of four additional cases for which records were available. Immunoreactive renin was present in ten of the 12 cases studied. In all of these cases, intense staining was present in vessels within the areas of the trapped cortex. In seven cases, renin was identified in the walls of vessels within the tumor itself without identifiable adjacent cortical structures. These findings indicate that CMN may often be associated with primary reninism in early infancy.

Humans↗
PubMed1988

Renin in human fetal lung--a biochemical and immunohistochemical study.

Human fetal lung homogenates contain an inactive form of renin which may be revealed by trypsin treatment. When activated, this form of renin has some biochemical similarities with fetal kidney renin: the pH optimum of fetal lung renin is approximately 6.5; it is bound by Affigel Blue affinity chromatography resin; and is inhibited by a monoclonal antibody (R-3-36-16) raised to human kidney renin. Inactive renin, partially-purified from both fetal kidney and lung, differs from this in that the renal form is of low-molecular weight (LMW, 45,000 daltons), whereas that from fetal lung is of high molecular weight (HMW, 58,000 daltons). Using a sensitive alkaline phosphatase-anti-alkaline phosphatase (APAAP) procedure with a polyclonal anti-renin antibody (R-15), immunoreactive renin in fetal lung was found in vessels in mesenchyme between airways. The pattern of staining was distributed similarly to Factor VIII-related antigen, suggesting localization in endothelial cells.

Fetus↗