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Biomedical subjects

Z Brown

Publications and source records attributed to Z Brown.

At least 19 recordsLinked to original sources
PubMed1997

Vaginal colonization by Escherichia coli as a risk factor for very low birth weight delivery and other perinatal complications.

This study evaluated the relationship of vaginal Escherichia coli colonization to birth weight <1500 g and other perinatal complications in a cross-sectional study of 2646 women at the University of Washington Medical Center, Seattle, between October 1992 and January 1995. Vaginal E. coli colonization was more strongly associated with delivery at <34 weeks (relative risk [RR], 1.7; 95% confidence interval [CI], 1.3-2.3) and very low birth weight (RR, 1.9; 95% CI, 1.3-2.7) than with prematurity between 34 and 36 weeks or low birth weight. Heavy growth of E. coli had a higher risk of very low birth weight than light growth (RR, 2.4; 95% CI, 1.0-6.2). It may be important to screen and treat pregnant women for genital tract colonization with E. coli during prenatal care.

Escherichia coli↗
PubMed1996

Regulation and expression of chemokines: potential role in glomerulonephritis.

Glomerular disease represent the major cause of renal failure. Despite decades of research or understanding of the mechanism(s) associated with immune-mediated glomerular injury remains poor. Consequently most of the therapies that are used are nonspecific with major side effects and offer minimal therapeutic benefits for the patient. The need for new strategies for therapy is clear. The drawing of leukocytes from the circulation into the inflamed glomerulus, accompanied by proliferation of resident mesangial cells and expansion of the mesangial matrix are key processes in the pathogenesis of glomerulonephritis (GN). The migration of inflammatory cells into an extravascular site requires a series of coordinated signals including the generation of a chemotactic gradient by the cells of extravascular compartment. The nature of the stimulus and the subsequent spectrum of chemotactic factors produced determine the specific leukocyte population recruited to the inflammatory site. Members of the chemokine family play a central role in this process by attracting and stimulating specific subsets of leukocytes. Our hypothesis is that mesangial cell-derived chemokines are responsible for the initiation and maintenance of glomerular inflammation; in this review we discuss our recent findings supporting this theory. Increasing our understanding of the intracellular pathway that regulate chemokine production in human mesangial cells may provide leads to the design of more effective therapies for the prevention and treatment of glomerular inflammation.

Chemokines↗
PubMed1995

Interleukin-1-induced IL-8 and IL-6 gene expression and production in human mesangial cells is differentially regulated by cAMP.

We have previously proposed that activated mesangial cells (MC) have a direct role in the initiation and propagation of inflammatory events within the glomerulus via the generation of the mesangioproliferative cytokine IL-6 and the chemokines IL-8 and MCP-1. The objective of this study was to investigate the role of cAMP in the regulation of IL-6 and IL-8 gene expression and peptide production in IL-1 stimulated human MC. Agents known to elevate cAMP, including dibutyryl cAMP (db-cAMP), forskolin or isobutyl-methylxanthine (IBMX) were alone unable to induce IL-6 or IL-8 expression or production above media control levels, indicating activation of the cAMP pathway could not mimic IL-1 signaling events. In the presence of IL-1, all three agents produced a marked potentiation of IL-6 mRNA expression and dose-dependent increase in IL-6 peptide production (twofold), but had little or no effect on IL-8 mRNA expression or peptide generation. In marked contrast cholera toxin (CT) caused a dose-dependent potentiation of both IL-1-induced IL-6 (approximately fourfold) and IL-8 peptide (approximately twofold) generation. The control agent, the purified binding subunit of cholera toxin (CT-B) which is devoid of ADP-ribosylating activity also enhanced IL-6 and IL-8 (approximately twofold) peptide generation indicating cAMP-independent mechanisms may be involved in the CT up-regulation of these cytokines. Treatment of MC with the cycloxygenase inhibitor indomethacin resulted in partial inhibition (37%) of IL-6 production but had no effect on IL-8 generation. Thus our data show that cAMP can potentiate IL-1 induced IL-6 production, while having no effect on IL-8 induction, and PGE2 may operate via a positive feedback loop to up-regulate IL-1 induced IL-6. Taken together, our results demonstrate that cAMP differentially regulates IL-6 and IL-8 production in IL-1-stimulated human MC.

Blotting, Northern↗
PubMed1995

Inducible nitric oxide synthase activity and expression in a human colonic epithelial cell line, HT-29.

1 We have determined which cytokines regulate the expression of human inducible nitric oxide synthase (iNOS) mRNA and nitrite generation in the human colonic-epithelial cell line HT-29. 2 Growth arrested cell cultures were stimulated with the human recombinant cytokines interleukin-1 alpha (IL-1 alpha), tumour necrosisfactor-alpha (TNF-alpha), interferon gamma (IFN-gamma) or vehicle added alone or in combination. Human iNOS mRNA was determined by Northern blot analysis and nitrite generation by the use of a fluorometric assay. 3 Unstimulated cells produced a small time-dependent increase in nitrite generation of 50 +/- 4, 75 +/- 8, and 103 +/- 8 nM per 10(6) cells at 24 h, 48 h, and 72 h respectively. This nitrite generation was unaffected by cycloheximide (5 micrograms ml-1) pretreatment and iNOS mRNA was not detected. 4 None of cytokines alone induced either iNOS mRNA expression or an increase in nitrite generation. The combination of IL-1 alpha/IFN-gamma produced a highly significant (P < 0.001) 4 fold increase in nitrite production at 48 h, compared to basal values, while no other pair of cytokines was effective. 5 Time course studies with IL-1 alpha/IFN-gamma combination revealed significant (P < 0.001) increases in nitrite at 24 h (153 +/- 7), 48 h (306 +/- 24), and 72 h (384 +/- 15) compared to basal values of 50 +/- 4, 75 +/- 8, and 103 +/- 8 nM per 10(6) cells respectively. 6 Studies with IL-1 alpha/IFN-gamma combination demonstrated a time dependent expression of iNOS mRNA, first observed at 6 h, peaked at 24 h and was undetectable by 72 h. IL-1 alpha (0.3-10 ng ml-1) and IFN-gamma (10-300 u ml-1) in combination induced a concentration-dependent expression of iNOS mRNA at 24 h. 7 Pretreatment with cycloheximide before IL-1 alpha/IFN-gamma stimulation reduced nitrite levels to basal values. These data suggest that the IL-1 alpha/IFN-gamma-induced nitrite production by HT-29 cells is dependent on de novo protein synthesis, probably the iNOS enzyme. 8 The addition of TNF-alpha produced a significant (P < 0.001) 3 fold increase of IL-1 alpha/IFN-gamma-induced nitrite generation. In marked contrast the presence of TNF-alpha had no effect on IL-1 alpha/IFN-gamma-induced iNOS mRNA expression by HT-29 cells. These findings suggest that the up-regulation by TNF-alpha of IL-1 alpha/IFN-gamma-induced nitrite generation is at the post-transcriptional level. 9 These data suggest that pro-inflammatory cytokines induce NO production in colonic epithelial cells probably due to the induction of iNOS and these cells may be a major source of NO generation in inflammatory bowel disease.

Cell Line↗
PubMed1994

Frequent detection of genital herpes simplex virus DNA by polymerase chain reaction among pregnant women.

OBJECTIVE: To investigate the prevalence and level of genital herpes simplex virus (HSV) among women at delivery. DESIGN, PATIENTS, AND SETTING: A prospective analysis of HSV by culture and by polymerase chain reaction (PCR) of genital specimens and by HSV serologic studies in 100 asymptomatic women in labor; prospective analysis of HSV by PCR among 50 seronegative nonpregnant women at a student health center; and retrospective analysis of genital specimens for HSV by PCR from 17 HSV culture-positive women with uninfected neonates and from two HSV culture-negative women with HSV-infected neonates. All pregnant women were at a university hospital. MAIN OUTCOME MEASURES: Presence of HSV by culture and levels of HSV by quantitative, type-specific PCR in cervical and vulvar specimens; HSV serologic testing by Western blot. RESULTS: All of the 100 asymptomatic women in labor who were studied prospectively were HSV culture negative. In nine HSV was recovered by PCR. Herpes simplex virus was recovered by PCR in one of the 50 seronegative nonpregnant women; she soon became seropositive. All 17 culture-positive women had HSV recovered by PCR. High levels of HSV DNA were obtained by PCR from the two culture-negative women with infected neonates. Among those from whom HSV was recovered by PCR, HSV DNA levels were 250 times higher from culture-positive samples than from culture-negative samples (11,571 genome equivalents vs 46 genome equivalents; P < .001). CONCLUSIONS: The frequency of infant exposure to HSV DNA-containing secretions from HSV-seropositive mothers is about eight times higher than previously reported using HSV culture methods. High maternal levels of HSV DNA may be associated with an increased frequency of transmission of HSV to the infant.

Base Sequence↗
PubMed1994

Long-term developmental follow-up of infants of diabetic mothers.

The neurodevelopmental consequences of maternal insulin-dependent diabetes were studied in 109 infants of diabetic mothers and 90 control infants. The infants born to diabetic mothers included 70 "early entry" subjects and 39 "late entry" subjects. Maternal diabetes control during pregnancy was significantly better in "early entry" mothers than in late-entry mothers, as determined by glycosylated hemoglobin levels. Infants were examined by a psychologist and a developmental pediatrician unaware of group status at 6, 12, 24, and 36 months of age; 71% of the subjects completed the 3-year-study. Neurodevelopment of early-entry subjects was similar to that of control subjects, whereas late-entry subjects scored less well on language measures. Mean head size in late-entry subjects was significantly less (p = 0.03) than in either control subjects or early-entry subjects at age 3 years, and correlated negatively with glycosylated hemoglobin levels during all three trimesters. Less optimal intellectual development was associated with reduced head circumference. In addition, the presence of major congenital malformations was associated with reduced developmental performance through age 2 years. Our results indicate that mothers with insulin-dependent diabetes who maintain good control during pregnancy can expect to have infants who are neurodevelopmentally normal; mothers whose diabetes is less well controlled may have infants with less optimal neurodevelopment.

Child Development↗
PubMed1994

Cocaine exposure during pregnancy: improving assessment with radioimmunoassay of maternal hair.

OBJECTIVE: To compare radioimmunoassay of postpartum maternal hair samples with a structured maternal interview for the detection of cocaine use during pregnancy. METHODS: Radioimmunoassay of hair samples obtained postpartum was compared with self-report of cocaine use obtained by confidential, structured interviews of 405 postpartum women. RESULTS: Cocaine or benzoylecgonine was detected in the hair samples of 129 of the 148 women (87%) who reported using cocaine at least once during pregnancy. Thirty-six of 257 women (14%) who reported that they had used no cocaine during pregnancy had positive hair tests. Positive hair assay with negative self-report was significantly more common among women who were unmarried (P = .001), African-American (P < .001), and multiparous (P = .035). CONCLUSIONS: Hair analysis is a valuable complement to maternal self-report by interview. The methods used together provide a useful clinical and research technique yielding a comprehensive estimate of gestational cocaine exposure. Either method alone may result in misclassification of gestational cocaine exposure.

Adult↗
PubMed1994

Chemokine gene expression and secretion by cytokine-activated human microvascular endothelial cells. Differential regulation of monocyte chemoattractant protein-1 and interleukin-8 in response to interferon-gamma.

The elicitation of leukocytes from the circulation to inflamed tissue depends on the activation of both the leukocyte and endothelial cell. In this study we determined the gene expression and secretion patterns for the chemokines interleukin-8 (IL-8) and monocyte chemoattractant protein-1 (MCP-1) in cytokine- and lipopolysaccharide (LPS)-treated cultured human lung microvascular endothelial cells (HLE). HLE constitutively expressed low levels of MCP-1 and IL-8. Treatment of HLE with a variety of cytokines and LPS up-regulated both IL-8 mRNA expression and release of immunoreactive IL-8 with an order of potency tumor necrosis factor-alpha (TNF-alpha) >> IL-1 alpha > LPS, whereas interferon-gamma (IFN-gamma) had no effect on IL-8 mRNA or antigenic levels. However, IFN-gamma, in combination with high doses of IL-1 alpha, resulted in a synergistic increase in IL-8 generation. MCP-1 gene expression and secretion was induced in a dose-dependent manner after IL-1 alpha, TNF-alpha, IFN-gamma, and LPS activation of HLE. IL-1 alpha was the most potent inducer of MCP-1 generation and LPS was relatively ineffective. IFN-gamma, in combination with low doses of IL-1 alpha, resulted in a synergistic increase in MCP-1 generation by HLE. These results demonstrate that although IL-8 and MCP-1 generation by HLE occurs on cytokine treatment, the relative ability of a given cytokine to elicit IL-8 generation is not directly parallel to effects on MCP-1 generation. These data suggest that the regulation of IL-8 and MCP-1 expression exhibit significant differences in their mechanisms. Such differences in the expression of specific chemokines may explain the specific appearance of various leukocytes at sites of inflammation and injury. These data also directly demonstrate that the lung microvascular endothelium contribute to the cytokine network of the lung, with the ability to respond to locally generated cytokines and to produce potent mediators of the local inflammatory response.

Base Sequence↗
PubMed1993

Effect of insulin-dependent diabetes on plasma lipoproteins in diabetic pregnancy.

A reduction in total plasma cholesterol concentration has been reported in insulin-dependent diabetic (IDDM) pregnant women in early gestation. To determine if this reduction extends throughout gestation and which lipoprotein fractions may be responsible, we measured plasma triglyceride, cholesterol (C), high density lipoprotein cholesterol (HDL-C) and HDL2 and HDL3-C subfractions between 6 and 36 weeks' gestation in normal and IDDM women. Total plasma C was significantly lower in IDDM pregnant subjects between 20 and 36 weeks' gestation as compared to nondiabetic controls, while plasma triglyceride concentrations were not significantly different in this interval. Very low and low density lipoprotein (VLDL, LDL) C concentrations were not statistically significantly different from controls at any of the times studied, while HDL-C was lower throughout diabetic pregnancy as compared to controls, significantly so between 20 and 36 weeks' gestation. The lower HDL-C in IDDM women was associated with a significantly lower HDL3-C level. Plasma apoprotein A-I and A-II concentrations, markers of the HDL2 and HDL3 subclasses, respectively, were measured to corroborate the HDL subfraction changes. Apo A-I and A-II increased significantly between 12 and 28 weeks' gestation in control but not in diabetic pregnant subjects, consistent with a higher HDL3 in normal than in diabetic pregnant subjects. It appears that plasma triglyceride, VLDL and LDL-C, and HDL2-C concentrations are similar in IDDM and normal pregnancy, while total-C, HDL-C and HDL3-C and its associated apoproteins are lower than in normal subjects in late gestation. The mechanism of these changes and their significance for fetal growth and development deserve further study.

Adult↗
PubMed1993

Human peritoneal mesothelial cells synthesize interleukin-8. Synergistic induction by interleukin-1 beta and tumor necrosis factor-alpha.

The present study demonstrates the synthesis and secretion of the neutrophil-activating peptide/interleukin-8 (IL-8) by cultured human peritoneal mesothelial cells (HPMC) and examines the regulation of its production by other cytokines. Unstimulated HPMC under growth-arrested conditions released IL-8 in a constitutive and time-dependent manner. Stimulation of HPMC with IL-1 beta or TNF-alpha resulted in a time- and dose-dependent IL-8 generation; after 24 hours the levels induced by IL-1 beta and TNF-alpha (both at 1000 pg/ml) were (mean +/- SEM, n = 5) 101 +/- 26.6 (z = 2.023; P < 0.01) and 35 +/- 8.09 (z = 2.023; P < 0.01) respectively. This release was inhibited following coincubation with the relevant anti-cytokine antibody or preincubation with either cycloheximide or actinomycin D. Treatment of HPMC with IL-1 beta or TNF-alpha resulted in increased levels of IL-8-specific mRNA. Stimulation of HPMC with combinations of IL-1 beta and TNF-alpha resulted in a synergistic increase in IL-8 release. This effect was significant at combined doses of IL-1 beta (50 pg/ml) and TNF-alpha (500 pg/ml) and above, when the release of IL-8 was 88 +/- 27% above the additive IL-8 release values (z = 2.201; P < 0.01). Western blot analysis using specific anti-IL-8 antibody demonstrated the presence of two major immunoreactive bands between 9 and 10 kd, in HPMC culture supernatants. These data demonstrate that HPMC synthesize IL-8 and that its release can be regulated as a result of induction of mRNA expression and de novo protein synthesis by other cytokines.

Base Sequence↗
PubMed1992

The Diabetes in Early Pregnancy Study: changes in cholesterol, triglycerides, body weight, and blood pressure. The National Institute of Child Health and Human Development--the Diabetes in Early Pregnancy Study.

This study examined changes in cholesterol, triglycerides, body weight, and blood pressure during pregnancy in 312 diabetic and 356 control women recruited within 21 days after conception. Cholesterol values rose in both groups but were significantly lower in diabetic women at each time point (166 vs 178 mg/dl at week 12, p = 0.0004). Triglyceride values also rose in both groups. Triglyceride levels did not differ between groups up to week 8 of gestation, but by weeks 10 to 12 they were significantly lower in diabetic women than in controls (75 vs 89 mg/dl at week 12, p = 0.0004). Although they were no heavier at entry, diabetic women gained significantly more weight between weeks 6 and 8 (p less than 0.001), resulting in a mean difference between groups of 1 kg. Systolic blood pressure increased steadily and significantly in the diabetic but not the control women (115.8 +/- 16.2 SD vs 109.3 +/- 11.8 mm Hg, p = 0.0006 at term). Diastolic blood pressure was higher in diabetic women on entry (70.7 vs 67.3 mm Hg, p = 0.0006) and throughout gestation. Significant correlations were found in the diabetic group between maternal blood pressure and lipids and infant birth weight. These newly found differences in cholesterol and triglyceride levels, weight gain, and blood pressure between type I diabetic and control women during gestation may have long-term cardiovascular implications.

Adult↗
PubMed1992

IL-1 receptor antagonist inhibits monocyte chemotactic peptide 1 generation by human mesangial cells.

The elicitation of neutrophils and monocytes from the circulation into the inflamed glomerulus is a key process in the pathogenesis of proliferative glomerulonephritis. The aim of this study was to determine the factors which regulate the expression and synthesis of the monocyte specific chemotaxin, monocyte chemotactic peptide 1 (MCP-1). Mesangial cells in culture did not constitutively express MCP-1, but could be induced to express both MCP-1 mRNA and antigenic MCP-1 by either stimulation with IL-1 alpha or TNF alpha, which are also stimuli for interleukin 8 (IL-8/NAP-1) expression and release. Pre-treatment of mesangial cells with the IL-1 receptor antagonist (IL-1ra) induced dose-dependent inhibition of both the expression of MCP-1 and IL-8 mRNA as well as the release of both chemotactic peptides in response to IL-1 alpha, while the receptor antagonist had no significant effect on TNF alpha induced MCP-1 and IL-8 generation. This study demonstrates that the IL-1 receptor antagonist was four times more effective at inhibiting the IL-1 induced expression and release of IL-8 compared to that of MCP-1. These results suggest that mesangial cell-derived MCP-1 may play an important role in the recruitment of monocytes in glomerular inflammation and that an IL-1 receptor antagonist may have therapeutic potential for the treatment of glomerulonephritis.

Base Sequence↗
PubMed1992

Herpes simplex virus-2 (HSV-2) type-specific antibody correlates of protection in infants exposed to HSV-2 at birth.

Western blot analysis was used to compare the herpes simplex virus (HSV)-2 antibody profiles of 40 infants less than 2 wk of age who had been exposed to maternal genital HSV-2 at birth. 4 mothers were HSV seronegative at delivery and seroconverted to HSV-2 ("primary infection"), 9 had HSV-1 antibodies and seroconverted to HSV-2 ("nonprimary first episode infection"), and 27 were HSV-2 seropositive ("recurrent infection"). Neonatal herpes infections developed in 1 of 4 infants of women with primary infection, in 3 of 9 infants of women with nonprimary first episode infection, and in none of the 27 infants of women with recurrent HSV-2. Antibodies to HSV-2 proteins gG-2, VP5, and ICP35 were detected in 83, 89, and 72% of the 36 uninfected infants, respectively. None of the four infected infants had detectable antibodies to gG-2 and only one (25%) had antibodies to VP5 or ICP35. The more limited profiles of the 13 infants born to mothers with first episodes of HSV-2 were then analyzed separately; these profiles were similar among infected and uninfected infants except for gG-2, which elicits antibodies that are type specific for HSV-2. None of the infected infants versus seven of nine (78%) uninfected infants were gG-2 seropositive. These comparisons suggest that maternal type-specific antibodies may play a role in preventing neonatal infection after exposure to HSV-2.

Antibodies, Viral↗