Biomedical subjects

L I Romero

Publications and source records attributed to L I Romero.

14 recordsLinked to original sources

PubMed2000

Differential expression of nitric oxide by dermal microvascular endothelial cells from patients with scleroderma.

Vascular abnormalities in scleroderma are fundamental to the pathogenesis of this disease. The objective of this study was to characterize dermal microvascular endothelial cells (DMEC) isolated from scleroderma patients with respect to growth and expression of the constitutive form of endothelial nitric oxide synthase (eNOS). DMEC from patients with both systemic sclerosis (SSc) and localized scleroderma (Loc Scl) contained small intact microvascular structures in contrast to single cell isolations obtained from control skin. Immunoaffinity selection on anti-PECAM-1 beads yielded pure populations of DMEC expressing normal markers. While the morphology and initial growth of SSc DMEC closely paralleled control cells, the growth of SSc DMEC decreased with time in culture (doubling time of 3 days vs. 5 days). Expression of ecNOS mRNA was reduced in both Loc Scl and SSc as shown by semi-quantitative RT-PCR (p < 0.001). Western blots showed variable but generally lower ecNOS protein levels and decreased levels of nitrogen oxides in media were found from both SSc and Loc Scl relative to control cells. The results indicate an intrinsic defect in the mechanism of nitric oxide production in DMEC isolated from scleroderma patients and suggest its possible involvement in the pathophysiology of scleroderma.

Adult↗

PubMed1999

Biodegradation kinetics of surfactants in seawater.

In this paper, a general kinetic model for degradation processes of surfactants is proposed. The model equation is v = K2S2 + K1S + K0, where v is the substrate consumption rate in the biodegradation process, S is the surfactant concentration in the medium and K2, K1, and K0 are kinetic constants. From this general expression, different simplified equations can be obtained (where K0 = 0; K2 and K0 = 0; K2 = 0; K2 and K1 = 0), which are representative of the process for different operating conditions. This model was tested by measuring the degradation of two different surfactants (Sodium dodecyl benzene sulfonate, LAS; and Sodium dodecyl sulfate, DSNa) under two different temperatures (5 and 20 degrees C). Values predicted by the model are close to experimental data obtained.

Benzenesulfonates↗

PubMed1998

Vascular abnormalities in scleroderma.

Vascular abnormalities represent a fundamental event in the pathogenesis of systemic sclerosis. This review focuses on key observations that support this view and builds a framework with which to clarify our understanding of how endothelial cell damage may trigger a self-fueling process ending in pathological tissue fibrosis in those susceptible to scleroderma. The studies reviewed in this article pertain to systemic sclerosis patients.

Humans↗

PubMed1998

Membrane-type matrix metalloproteinases in human dermal microvascular endothelial cells: expression and morphogenetic correlation.

Membrane-type matrix metalloproteinases (MT-MMP) activate the zymogen form of MMP-2/Gelatinase A on cell surfaces and are expressed in invasive tumors. We sought to identify and characterize MT-MMP in a non-malignant cell type that undergoes a physiologic and reversible invasive phenotype during angiogenesis. Human dermal microvascular endothelial cells (HDMEC) were isolated from neonatal tissue and purified by anti-CD31 (PECAM) affinity beads. MT-MMP-1 and -3 transcripts were amplified by reverse transcriptase-polymerase chain reaction and northern blots showed a single 4.5 kB mRNA for MT-MMP-1 that was modulated by angiogenic factors and phorbol ester. Immunoblotting of reduced cellular extracts with different MT-MMP-1 antibodies showed the presence of the 63-65 kDa and 57-60 kDa forms, as well as additional forms at lower molecular weights. HDMEC membranes extracted with Triton X114 were incubated with gelatin-sepharose purified MMP-2 and MMP-9 to show activation of proenzymes. Pre-incubation of HDMEC with anti-MT-MMP-1 antibodies decreased proMMP-2 conversion activity only. The movement of HDMEC and the formation of tubule-like structures in three-dimensional collagen gels was markedly delayed by preincubation with the same anti-MT-MMP-1 antibodies. These results demonstrate the presence of MT-MMP in cutaneous microvascular cells in vitro. Modulation of these cell surface proteinases by angiogenic factors, demonstration of multiple processed forms, and specific attenuation of HDMEC morphogenetic patterns in three-dimensional collagen gels implicate their potential roles in the formation of new blood vessels in the skin.

Angiogenesis Inducing Agents↗

PubMed1997

Interleukin-1 induces major phenotypic changes in human skin microvascular endothelial cells.

To determine the role of the pleiotropic cytokine interleukin-1 (IL-1) on the activation of endothelial cells during inflammation and angiogenesis, pure populations of human dermal microvascular endothelial cells (HDMEC) were obtained by immunoaffinity purification using Ulex europaeus agglutinin-1 and platelet endothelial cell adhesion molecule-1 (PECAM-1) antibody. Exposure of HDMEC to IL-1beta induced morphologic and physiologic changes characterized by 1) phenotypic modulation of endothelial cells from epithelioid to spindle-shaped cells accompanied by reorganization of vimentin filaments; 2) gradual decrease to a complete absence of the endothelial cell markers von Willebrand factor (vWf) and PECAM-1; and 3) increased capability to form tubule-like structures when overlaid with collagen gels. The IL-1 effect on cell morphology, growth, and decrease of endothelial cell antigens was potentiated by basic fibroblast growth factor (bFGF). Similar results were observed in mitotically arrested gamma-irradiated cells demonstrating that the spindle-shaped cells observed after IL-1 stimulation were derived from epithelioid endothelial cells and that DNA synthesis was not required to effect these changes. Immunostaining with an antibody specific for human fibroblasts was negative and further confirmed the endothelial cell origin of the spindle-shaped cells. These data demonstrate that IL-1 can induce phenotypic changes in HDMEC from epithelioid to spindle-shaped, mesenchymal-like cells, that these cells are more susceptible to stimulation by bFGF, and that they lose biochemical and functional properties characteristic of epithelioid HDMEC.

Cell Division↗

PubMed1996

Interleukin-10 induces E-selectin on small and large blood vessel endothelial cells.

In vitro, expression of E-selectin is largely restricted to endothelial cells activated by inflammatory cytokines. Under activated conditions, cytokines such as interleukin (IL) 10, released by keratinocytes in large quantities, may also increase the expression of E-selectin on the dermal microvasculature. The aim of the present study was to investigate the expression of E-selectin on cultured human dermal microvascular endothelial cells (HDMEC) isolated from neonatal foreskins when exposed to IL-10. Expression of E-selectin was determined by immunofluorescence microscopy, FACS analysis, an HL-60 cell-binding assay, and quantitative polymerase chain reaction (PCR) analysis. For comparison with large blood vessel cells, the expression of E-selectin on human umbilical vein endothelial cells (HUVEC) was also determined in parallel by FACS and reverse transcriptase-PCR analysis under identical conditions. These studies demonstrate that IL-10 induces the expression of E-selectin on both HDMEC and HUVEC and that the level of expression of HDMEC is comparable with that induced by IL-1 beta and tumor necrosis factor-alpha. When HL-60 cells are incubated with HDMEC pretreated with IL-10, a consistent increase in adherence of HL-60 to endothelial cells is observed. This adherence was found to be mediated by L-selectin. PCR analysis and the quantification of E-selectin cDNA by a novel, highly sensitive and specific PCR-immunoassay demonstrate the induction of E-selectin mRNA at the transcriptional level. The induction of the expression of E-selectin by IL-10 on HDMEC may provide additional insights into the pathogenic mechanism of neutrophil accumulation at the site of inflammation in inflammatory skin diseases.

Cell Adhesion↗

PubMed1996

Roles of IL-1 and TNF-alpha in endotoxin-induced activation of nitric oxide synthase in cultured rat brain cells.

In astrocytes and microglia, bacterial lipopolysaccharide (LPS) stimulates production and release of interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), and nitric oxide (NO). Although IL-1 beta and TNF-alpha are themselves capable of inducing NO synthase (NOS) in glia, the specific factors mediating LPS induction of NOS in brain have not been identified. To determine whether LPS induction of NOS in brain cells is mediated by IL-1 or TNF-alpha, acting alone or in concert, the effects of IL-1-receptor antagonist (IL-1Ra) and of TNF-soluble receptor (TNFsRp55), presented individually and in combination, on LPS-induced NOS activity were tested. In glial-enriched mixed primary cultures of neonatal rat telencephalic cells, LPS (0.1-100 ng/ml), IL-1 beta (0.01-10 nM), and TNF-alpha (0.1-100 nM) each concentration dependently stimulated accumulation of nitrite, an indicator of NO production. Induction of nitrite accumulation by LPS and by IL-1 was blocked by N omega-nitro-L-arginine methyl ester and N omega-monomethyl-L-arginine, indicating that it was mediated by NOS. TNF-alpha alone induced NO production weakly as compared with IL-1, but combined submaximal concentrations of IL-1 beta (1 nM) and TNF-alpha (10 nM) induced NOS synergistically. Furthermore, TNFsRp55 and IL-1Ra each produced a dose-dependent partial inhibition of the NO response to LPS, and the effect of TNFsRp55 was equal to or greater than that of IL-1Ra. TNFsRp55 and IL-1Ra in combination were not significantly more effective than TNF-sRp55 alone. The results indicate that LPS induction of NOS activity in brain cells is mediated in part by both IL-1 beta and TNF-alpha.

Animals↗

PubMed1996

Interleukin-6 (IL-6) is secreted from the brain after intracerebroventricular injection of IL-1 beta in rats.

To test the hypothesis that the brain is a source of the interleukin-6 (IL-6) that appears in the peripheral circulation of rats after intracerebroventricular (icv) injection of IL-1 beta, the concentration of bioactive IL-6 in superior sagittal sinus (SSS) blood plasma was compared with aortic plasma 4 h after icv injection of 100 ng of recombinant human IL-1 beta at a time at which cerebrospinal fluid (CSF) IL-6 concentration was found to be markedly elevated. In three separate experiments, CSF IL-6 concentration (pg/ml; values are means +/- SE) was significantly elevated after icv IL-1 beta compared with saline control injections (25,879 +/- 11,472 vs. 35.5 +/- 5; 32,323 +/- 4,945 vs. 128 +/- 29; 114,410 +/- 33,563 vs. 848 +/- 250, respectively). The concentration of plasma IL-6 (pg/ml) in the aortas of rats injected intracerebroventricularly with IL-1 was greater than in controls [252 +/- 93 vs. 36.7 +/- 8.3, P = 0.0037; 361 +/- 95 vs. 57 +/- 13, P = 0.02; 2,254 +/- 550 vs. 1,239 +/- 666, P = 0.26 (NS)]. In IL-1-injected animals, SSS venous plasma IL-6 (pg/ml) was greater than in the aorta in all three studies (1,617 +/- 357 vs. 252 +/- 93, P = 0.0011; 3,754 +/- 1,188 vs. 361 +/- 95, P = 0.024; 8,208 +/- 1,388 vs. 2,254 +/- 550, P = 0.0054). The concentration difference (pg/ml) between SSS and aorta was significantly greater after IL-1 beta injection than in diluent-injected animals (1,365 +/- 369 vs. 48.3 +/- 13, P = 0.0083; 3,393 +/- 1,203 vs. 126 +/- 59, P = 0.035; 5,954 +/- 1,260 vs. 494 +/- 774, P = 0.0042). Suppression of peripheral sympathetic activation by preganglionic cholinergic blockade (chlorisondamine, 250 micrograms sc) did not prevent the usual IL-1-induced elevation in aortic blood IL-6 (3,272 +/- 1,174 vs. 244 +/- 74 pg/ml, P = 0.0012) nor the increased SSS-aortic gradient (2,541 +/- 1,134 vs. 165 +/- 48, P = 0.0142 by Mann-Whitney comparison). Injection of rat/human corticotropin-releasing hormone (CRH; 10.0 micrograms) icv did not change IL-6 concentration in CSF or in peripheral blood. These studies demonstrated that the brain and/or its supporting structures are activated by icv IL-1 beta to release IL-6 into the blood and that the effect is not dependent on peripheral sympathetic activity or central mobilization of CRH. Direct secretion of IL-6 and possibly of other cytokines from the brain is postulated to be a pathway of neuroimmunomodulation.

Animals↗

PubMed1994

Borrelia burgdorferi and Escherichia coli lipopolysaccharides induce nitric oxide and interleukin-6 production in cultured rat brain cells.

Borrelia burgdorferi, the spirochetal agent of Lyme disease, infects the central nervous system (CNS), but the factors that mediate inflammation and neurologic dysfunction are not known. Sonicated B. burgdorferi stimulated in a concentration-dependent manner the production of nitric oxide (NO) in glial-enriched primary cultures of neonatal rat brain cells via induction of NO synthase activity. Lipopolysaccharide (LPS) of Escherichia coli also stimulated nitrite accumulation in a concentration-dependent manner. Stimulation of NO production by B. burgdorferi sonicate and E. coli LPS was associated with increased levels of mRNA coding for the cytokine-inducible form of NO synthase. B. burgdorferi sonicate also stimulated release of interleukin-6, with a concentration-response relationship similar to that for its stimulation of nitrite production, as did E. coli LPS. A competitive antagonist of E. coli LPS, Rhodopseudomonas sphaeroides lipid A, inhibited LPS-induced stimulation of NO synthase activity but markedly potentiated that of B. burgdorferi, indicating that the initial triggering mechanism of B. burgdorferi is distinct from that of E. coli LPS. Induction of NO synthase by bacterial agents within the brain may represent a common pathway of CNS inflammation and neurotoxicity.

Amino Acid Oxidoreductases↗

PubMed1994

Suppression of thyrotropin-releasing hormone gene expression by interleukin-1-beta in the rat: implications for nonthyroidal illness.

Nonthyroidal illness is characterized by low thyroid hormone levels and inappropriately normal or decreased TSH levels. To determine whether the hypothalamus contributes to these responses, TRH gene expression in hypophysiotropic neurons of the paraventricular nucleus (PVN) was investigated using semiquantitative in situ hybridization histochemistry in an animal model of nonthyroidal illness. Following the systemic administration of bacterial lipopolysaccharide (LPS; 250 micrograms/100 g BW), plasma T4, T3 and TSH were reduced but this was not associated with an increase in the content of proTRH mRNA in the PVN as occurs when plasma T4 and T3 concentrations fall during primary hypothyroidism. Constant infusion of human interleukin-1 beta (IL-1 beta) into the cerebrospinal fluid also reduced plasma T4 concentration. This persisted for the duration of the infusion but TSH was only suppressed after 7 days of infusion when body weight had declined. By 24 h, the content of proTRH mRNA in the PVN in IL-1 beta infused animals was significantly reduced from control values. These studies indicate that the peripheral administration of endotoxin or central administration of IL-1 beta in the rat is associated with a proTRH mRNA content in the PVN that may be inappropriately normal or reduced for the level of circulating thyroid hormone. We propose that the inability of hypophysiotropic neurons to induce TRH gene expression in nonthyroidal illness, when circulating thyroid hormone levels are low, is one of several factors that contributes to the inability of the anterior pituitary to increase its secretion of TSH.

Animals↗

PubMed1993

Bacterial lipopolysaccharide induction of IL-6 in rat telencephalic cells is mediated in part by IL-1.

Interleukin-6 (IL-6) appears in the cerebrospinal fluid (CSF) of patients with acute infection of the central nervous system, and in the brains and CSF of experimental animals following systemic or intracerebral injection of bacterial endotoxin (Escherichia coli lipopolysaccharide, LPS). Since LPS is known to induce secretion of interleukin-1 (IL-1) in many cell types including those of the brain, and IL-1 can induce IL-6 in brain tissue it appeared reasonable to postulate that the effects of LPS on IL-6 production were mediated through IL-1 induction. To test this hypothesis, the effects of IL-1 receptor antagonist (IL-1Ra) on LPS and IL-1-induced IL-6 secretion were tested in a mixed brain cell culture from 17-day fetal rat, after 12-14 days in culture. IL-6 secretion was induced by IL-1 beta in a concentration as low as 1 x 10(-10) M (p = 0.0008); addition of IL-1Ra was shown to inhibit IL-1-induced changes by 87% (p = 0.0012) at a molar ratio of 100:1, and by 100% at a molar ratio of 1,000:1, LPS stimulated IL-6 secretion progressively over the concentration of 1-100 ng/ml (p = 0.0001). LPS 10 ng/ml-induced IL-6 secretion was inhibited by 66% by IL-1Ra in a concentration of 1,000 ng/ml (p = 0.0077). The inhibitory effect of IL-1Ra was not significantly greater even when used at a concentration of 5,000 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

In situ localization of interleukin-6 in normal skin and atrophic cutaneous disease.

Interleukin-6 (IL-6) is a multifunctional cytokine that participates in the inflammatory and immune responses. In human skin, keratinocytes produces IL-6, although the in vivo role of this cytokine is unknown. In the present study we investigated the in situ localization of IL-6 in normal epidermis (n = 10) and in a group of skin diseases characterized by epidermal atrophy. Formalin-fixed paraffin-embedded skin biopsies from patients with clinical and histopathological features consistent with localized scleroderma (n = 10), systemic scleroderma (n = 5), lichen sclerosus et atrophicus (n = 9) and balanitis xerotica obliterans (n = 7) were tested using polyclonal antibodies and avidin-biotin-peroxidase immunostaining. We demonstrated the presence of IL-6 in normal epidermis and in atrophic skin diseases. In normal skin there was moderate intercellular and intracellular reactivity detected using a high antibody concentration. In specimens with epidermal atrophy we detected intense cytoplasmic and intercellular immunostaining using a lower antibody concentration. The immunoreactivity was independent of the epidermal thickness. Plasma IL-6, measured by radioimmunoassay, was not elevated in plasma from patients with localized or systemic scleroderma. Increased IL-6 in the epidermis of selected skin diseases suggests that IL-6 may be related to the pathophysiology of dermatologic diseases characterized by epidermal atrophy.

Antibody Specificity↗

PubMed1989

In situ localization of interleukin-1 in normal and psoriatic skin.

Interleukin-1 (IL-1) is a family of polypeptides that mediates a wide range of inflammatory and immune responses. In human skin, unstimulated keratinocytes produce a large amount of such cytokines. Although the precise role of IL-1 in the skin is unknown, there is experimental evidence supporting involvement of IL-1 in the pathogenesis of inflammatory skin diseases. In this study, we investigated in situ localization of IL-1 alpha and IL-1 beta in normal and psoriatic skin. Using polyclonal antibodies and the avidin-biotin peroxidase complex, we demonstrated the presence of both IL-1 alpha and IL-1 beta in normal and psoriatic formalin-fixed paraffin-embedded tissues. In both cases, IL-1 alpha was more prominent. However, the distribution of IL-1 alpha differed between normal and psoriatic skin. In normal skin, IL-1 alpha distribution was predominantly intercellular, whereas IL-1 alpha distribution was predominantly within the cytoplasm in psoriatic skin. These studies confirm that IL-1 alpha is the predominant form of IL-1 in the skin and provide further support for the hypothesis that IL-1 participates in the pathogenesis of psoriasis.

Adult↗

PubMedDate not supplied

Thermophilic anaerobic degradation of distillery wastewater in continuous-flow fluidized bed bioreactors.

This paper reports and discusses a laboratory experiment that tested the anaerobic fluidized bed (AFB) technology as a means for the treatment of concentrated industrial wastewater (wine distillery, vinasses) at thermophilic conditions. The purposes were to operate and characterize AFB under high organic loading conditions and to report on their steady-state performance. Experimentally, it was confirmed that AFB systems can achieve > 82.5% chemical oxygen demand (COD) reduction at a COD loading of 32.3 kg of COD m-3 day-1 for treating vinasses of wine. At hydraulic retention time (HRT) of 0.46 day, the volumetric rate of methane generation was 5.8 m3 of CH4 m-3 day-1 with a methane yield of 0.33 m3 of CH4/kg of COD removal. The greatest efficiency of substrate removal was 97% for an organic loading rate of 5.9 kg of COD m-3 day-1 and HRT of 2.5 days. The food-to-microorganism (F:M) ratio can be used as a parameter for treatment performance evaluation of AFB. For vinasses, excellent COD reduction and methane production were achievable at the F:M ratio of 0.55 kg of COD kg-1 VSatt day-1 (more than 80% of feed COD was removed, and 9 m3 m-3 day-1 of methane was produced).

Industrial Waste↗