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Biomedical subjects

M Velez

Publications and source records attributed to M Velez.

At least 19 recordsLinked to original sources
PubMed2003

Effects of iron deficiency on the secretion of interleukin-10 by mitogen-activated and non-activated murine spleen cells.

Interleukin (IL)-10 plays crucial regulatory roles in immune responses by inhibiting the secretion of several cytokines (IL-2, IL-12, interferon-gamma (IFN-gamma)) and lymphocyte proliferation. Iron deficiency, a public health problem for children, alters these immune responses. To determine whether these changes are related to altered IL-10 secretion, we measured IL-10 in 24 and 48 h supernatant of spleen cell cultures from iron deficient (ID), control (C), pairfed (PF), and ID mice fed the control diet (iron repletion) for 3 (R3) and 14 (R14) days (d, n = 12/group). Mean levels of hemoglobin, hematocrit, and liver iron stores varied as follows: C approximately equal PF approximately equal R14 > R3 > ID (P < 0.01). Mean baseline IL-10 levels of ID mice tended to be higher than those of other groups (P > 0.05, ANOVA). Mean IL-10 levels secreted by concanavalin A (Con A) and antibody raised against cluster of differentiation molecule 3 (anti-CD3)-treated cells (+/-background) were lower in ID than in C (48 h) and iron replete mice (P < 0.05). Underfeeding also reduced IL-10 secretion by anti-CD3-treated cells (48 h, P < 0.05). Lymphocyte proliferative responses to anti-CD3 +/- anti-CD28 antibodies were lower in ID than in C and PF mice, and they were corrected by iron repletion (P < 0.05). IL-10 levels negatively correlated with indicators of iron status (r <or= -0.285) and lymphocyte proliferation (r <or= -0.379 [r <or= -0.743 for ID mice]), but positively correlated with IFN-gamma levels (r <or= 0.47; P < 0.05). Data suggest that iron deficiency has a generalized deleterious effect on cells that secrete both cytokines. Reduced IL-10 secretion by activated cells does not overcome the inhibition of lymphocyte proliferation due to other factors of T cell activation that are regulated by iron.

Animals↗
PubMed2003

Non-ablative facial skin photorejuvenation with an intense pulsed light system and adjunctive epidermal care.

Laser skin resurfacing is popular, but the appearance of the face during healing is unpleasant. Non-ablative photorejuvenation with intense pulsed light (IPL) has been reported as being successful but with varied results. In this study we sought the possibility of enhancing the clinical effects with adjunctive epidermal care. Twenty-five women aged from 32 to 68, skin types I-IV, with a variety of wrinkle types and other conditions associated with photoaged skin, were treated with IPL according to our parameters over six sessions coupled with an adjunctive pretreatment micropeel and applications of nutritive and antipigmenting creams. Macroscopic and histological assessments were performed. At weeks 4 and 8 fair to good satisfaction was noted in 17 and 19 patients, and poor satisfaction in 8 and 6 patients, respectively. The histology showed good dermal collagen remodelling in all cases, with a reduction in elastosis. The results of IPL photorejuvenation can be enhanced, as our trials showed. The good patient satisfaction obtained was clearly demonstrated in the histologies and evaluations throughout the study.

Adult↗
PubMed2001

Hepatitis C virus infection-related morbidity and mortality among patients with human immunodeficiency virus infection.

Hepatitis C virus (HCV) has emerged as a major pathogen among patients with human immunodeficiency virus (HIV). Morbidity and mortality were compared among 263 patients with HIV alone, 166 patients with HIV and HCV, and 60 patients with HCV alone (mean duration of follow-up, 2 years and 10 months). No differences in HIV loads and CD4 cells counts were observed between the HIV and HIV/HCV groups. Alanine aminotransferase levels were higher (52 U/L versus 35 U/L; P<.05) and albumin levels were lower (3.5 g/dL versus 3.8 g/dL; P <.02) among coinfected patients than they were among patients with HIV alone. Liver decompensation developed in 10% of patients with HIV/HCV coinfection. In contrast, no liver-related deaths or decompensation occurred in patients without coinfection (P<.05). Of the patients with HIV alone, 7% died, compared with 11% of the coinfected patients (P<.02); 47% of the deaths in the latter group were due to liver-related causes. In summary, HCV infection causes increased morbidity and mortality in patients with HIV infection.

AIDS-Related Opportunistic Infections↗
PubMed2000

Influence of chronic alcohol abuse on hepatitis C virus replication.

BACKGROUND: Patients with alcoholic liver disease have a high prevalence of hepatitis C virus (HCV) infection. Several workers have shown that HCV-infected alcoholics have more severe biochemical and histological evidence of liver disease than anti-HCV-negative patients. One possible mechanism for the increased liver damage is that alcohol may have a stimulatory effect on HCV replication. The present study was carried out to examine this issue in detail. METHODS: Sixty-eight HCV-infected patients, comprising of 50 chronic alcoholics, consuming 80 g or more of alcohol daily for at least 5 years, and 18 completely abstinent subjects were included in the study. Quantitative HCV-RNA was performed by the branched chain DNA (bDNA) technique. RESULTS: There was no significant difference in the mean serum HCV titers in chronic alcoholics compared to nonalcoholic subjects. Linear regression analysis showed no correlation between the daily ethanol consumption and HCV titers. Seven of the chronic alcoholics, 4 of whom were continuing to drink and 3 who had become abstinent, were retested after 6 months. There was no definite trend in the viral titers, either in abstinent individuals or in those who continued to drink. CONCLUSIONS: These findings suggest that chronic alcohol abuse does not influence the HCV load in the serum. Therefore, the observation that alcoholics with HCV infection have more severe liver damage requires some other explanation than increased HCV viral titers.

Alcoholism↗
PubMed2000

Association between increased levels of TNF-alpha, decreased levels of prealbumin and retinol-binding protein, and disease outcome.

We determined whether there is an association between tumor necrosis factor-alpha (TNF-alpha), undernutrition [prealbumin (PA) <160 mg/L, retinol binding protein (RBP) <30 mg/L], disease stage, outcome (death or survival), and race in children with leukemia. TNF-alpha, PA, and RBP were measured in 52 patients (0.8 to 17 years old): 18 African Americans, 34 whites; 27 newly diagnosed (ND), and 25 in clinical remission (CR). Mean levels of TNF-alpha were higher in patients than in 46 healthy children (p < 0.05), but were not different between ND and CR groups. Mean acute phase proteins (APP) were different among groups: ND > CR > controls (p < 0.05). Mean levels of PA and RBP were lower in patients than in controls (p < 0.051, and tended to be higher in CR than in ND patients. African-American patients had lower concentrations of TNF-alpha, PA, and RBP but higher APP than white patients (p < 0.05). CR patients and African-American patients who died tended to have higher levels of TNF-alpha and APP, but lower PA and RBP than those who survived. A higher percentage of ND African Americans (45%) than of ND whites (13%) died. Results suggest that undernutrition and inflammation in CR patients and African Americans were associated with poor survival, and that ND African Americans have a poorer outcome than whites independently of TNF-alpha levels.

Acute-Phase Proteins↗
PubMed1997

Software for the competitive edge.

In choosing computer software and hardware that will help their agencies run smoothly, providers face a sometimes overwhelming task. One agency shares its success in achieving a competitive edge using "off-the-shelf" software rather than spending money on more expensive, customized solutions.

Computer Communication Networks↗
PubMed1990

Rotational diffusion of acetylcholine receptors on cultured rat myotubes.

The rotational mobility of acetylcholine receptors (AChR) in the plasma membrane of living rat myotubes in culture is measured in this study by polarized fluorescence recovery after photobleaching (PFRAP). These AChR are known to exist in two distinct classes, evident by labeling with rhodamine alpha-bungarotoxin; clustered AChR that are aggregated in a pattern of highly concentrated speckles and streaks, with each cluster occupying an area of approximately 1,000 microns 2; and nonclustered AChR that appear as diffuse labeling. PFRAP results reported here show that: (a) most clustered AChR (approximately 86%) are rotationally immobile within a time scale of at least several seconds; and (b) most nonclustered AChR (approximately 76%) are rotationally mobile with characteristic times ranging from less than 50 ms to 0.1 s. External cross-linking with the tetravalent lectin concanavalin A immobilizes many nonclustered AChR. PFRAP experiments in the presence of carbachol or cytochalasin D show that the restraints to rotational motion in clusters are remarkably immune to treatments that disperse clusters or disrupt cytoplasmic actin. The experiments also demonstrate the feasibility of using PFRAP to measure rotational diffusion on selected microscopic areas of living nondeoxygenated cells labeled with standard fluorescence probes over a very wide range of time scales, and they also indicate what technical improvements would make PFRAP even more practicable.

Animals↗
PubMed1990

Characterization of gentamicin-resistant respiratory-deficient (res-) variant strains of Staphylococcus aureus.

Exposure of sensitive cells of Staphylococcus aureus to concentrations of gentamicin higher than the minimal inhibitory concentration, results in the recovery of low level resistant strains with a greatly altered phenotype (variants). Because the phenotypic alteration in these strains is so great the expected diagnostic characterization of these variants as S. aureus is obscured. Starting with a genetically-marked parent strain, a comprehensive cytological, physiological, morphological, genetic and biochemical analysis of the variants isolated from it was carried out. The genetic lineage of the variants to the parent was also established by DNA/DNA hybridization. Variants result from mutations in the hemin biosynthesis locus, the effect of which is to disrupt the synthesis of components of the electron transport system, lipid synthesis and selected nucleotide synthesis. Thus the strains are defective in aerobic and anaerobic respiration, (res-), in active transport of aminoglycosides (which confers low level resistance), export of characteristic exo-enzymes, and in cell wall composition and structure.

Bacteriophages↗
PubMed1989

Microfilaments and actin-associated proteins at sites of membrane-substrate attachment within acetylcholine receptor clusters.

Rat myotubes in tissue culture form broad areas of close contact with the substrate. These areas often display two distinct, interdigitating sets of membrane domains. One, the "contact domain", is close to the substrate; the other, termed the "AChR domain", is further from the substrate and is rich in acetylcholine receptors (AChR). We have used fluorescence techniques to study the organization of the cytoskeleton in these areas. Substrate-apposed membrane of the myotubes was exposed either by shearing or by permeabilizing the cells with a neutral detergent. Phalloidin derivatives and affinity-purified polyclonal or monoclonal antibodies specific for cytoskeletal proteins were then applied to the samples. Sheared samples were observed by epifluorescence microscopy; detergent-permeabilized samples were observed by total internal reflection fluorescence microscopy. We found that, like antivinculin, fluorescent phalloidin derivatives and antibodies to alpha-actinin, filamin, and talin preferentially labeled the contact domains. This suggests that bundles of microfilaments associate with the membrane at sites of myotube-substrate attachment. In contrast, a 43K protein, closely associated with AChR, was present only at AChR domains. A monoclonal antibody to actin labeled both AChR and contact domains, suggesting that actin is enriched over both regions. Our results suggest that, like the plasma membrane of AChR clusters, the underlying membrane skeleton is organized into at least two distinct domains.

Actin Cytoskeleton↗