Biomedical subjects

M Perez

Publications and source records attributed to M Perez.

At least 37 records · Page 2Linked to original sources

PubMed2001

Nutritional status impairments in HIV-infected patients are associated with increased TNF-alpha and IL-6 serum levels but not with viral load.

BACKGROUND: Cytokines may alter metabolic pathways and contribute to malnutrition among human immunodefiency virus (HIV)-positive individuals. PATIENTS AND METHODS: Tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), soluble IL-2 receptors (sIL-2R), beta2-microglobulin serum levels and plasma viral load of 45 HIV-positive patients were determined and correlated to nutritional status impairment. Patients were grouped by CD4 counts into categories I (< 200/microl), II (200-499/microl), III (> or = 500/microl). There were 15 healthy controls. A nutritional grading system, based on anthropometric and laboratory data, was devised. Scores ranged from 0 to 5 (eutrophic to malnutrition). RESULTS: AIDS patients' cytokines and immune marker levels were significantly higher than those of the controls, but not always higher than those of other categories. AIDS patients had higher nutritional deficit grades than category III (p < 0.05) or the controls (p < 0.02) which, except for viral load, correlated with the parameters studied. CONCLUSION: Nutritional status impairments in HIV-positive individuals were associated with immune activation but not with viral load.

Adult↗

PubMed2001

On fatalism, pessimism, and depressive symptoms among Mexican-American and other adolescents attending an obstetrics-gynecology clinic.

There is growing evidence that Mexican-American adolescents may be at increased risk for depressive symptoms. We sought to replicate and explain this result in a study of adolescent girls attending an obstetric-gynecologic clinic. Three hundred and four girls of diverse ethnic backgrounds completed measures of depressive symptoms, negative attributional style, and locus of control. Consistent with predictions, we found that Mexican-American adolescent girls reported more depressive symptoms than adolescent girls from other ethnic backgrounds, and that Mexican-American adolescent girls displayed more negative cognitive styles than girls from other ethnic backgrounds. Depression differences appeared to be partly explained by differences in negative cognitive style. Implications of the results for a theory of increased Mexican-American adolescent depression, and for applied work, were discussed.

Adolescent↗

PubMed2001

Kinetics of thermophilic anaerobes in fixed-bed reactors.

The main objective of this study is to estimate growth kinetic constants and the concentration of "active" attached biomass in two anaerobic thermophilic reactors which contain different initial sizes of immobilized anaerobic mixed cultures and decompose distillery wastewater. This paper studies the substrate decomposition in two lab-scale fixed-bed reactors operating at batch conditions with corrugated tubes as support media. It can be demonstrated that high micro-organisms-substrate ratios favor the degradation activity of the different anaerobic cultures, allowing the stable operation without lag-phases and giving better quality in effluent. The kinetic parameters obtained--maximum specific growth rates (mu(max)), non-biodegradable substrate (S(NB)) and "active or viable biomass" concentrations (X(V0))--were obtained by applying the Romero kinetic model [L.I. Romero, 1991. Desarrollo de un modelo matemático general para los procesos fermentativos, Cinética de la degradación anaerobia, Ph.D. Thesis, University of Cádiz (Spain), Serv. Pub. Univ. Cádiz], with COD as substrate and methane (CH4) as the main product of the anaerobic process. This method is suitable to calculate and to differentiate the main kinetic parameters of both the total anaerobic mixed culture and the methanogenic population. Comparison of experimental measured concentration of volatile attached solids (VS(att)) in both reactors with the estimated "active" biomass concentrations obtained by applying Romero kinetic model [L.I. Romero, 1991. Desarrollo de un modelo matemático general para los procesos fermentativos, Cinética de la degradación anaerobia, Ph.D. Thesis, University of Cádiz (Spain), Serv. Pub. Univ. Cádiz] shows that a large amount of inert matter is present in the fixed-bed reactor.

Bacteria, Anaerobic↗

PubMed2001

Congenital heart block: development of late-onset cardiomyopathy, a previously underappreciated sequela.

OBJECTIVE: We report 16 infants with complete congenital heart block (CHB) who developed late-onset dilated cardiomyopathy despite early institution of cardiac pacing. BACKGROUND: Isolated CHB has an excellent prognosis following pacemaker implantation. Most early deaths result from delayed initiation of pacing therapy or hemodynamic abnormalities associated with congenital heart defects. METHODS: A multi-institutional study was performed to identify common clinical features and possible risk factors associated with late-onset dilated cardiomyopathy in patients born with congenital CHB. RESULTS: Congenital heart block was diagnosed in utero in 12 patients and at birth in four patients. Ten of 16 patients had serologic findings consistent with neonatal lupus syndrome (NLS). A pericardial effusion was evident on fetal ultrasound in six patients. In utero determination of left ventricular (LV) function was normal in all. Following birth, one infant exhibited a rash consistent with NLS and two had elevated hepatic transaminases and transient thrombocytopenia. In the early postnatal period, LV function was normal in 15 patients (shortening fraction [SF] = 34 +/- 7%) and was decreased in one (SF = 20%). A cardiac pacemaker was implanted during the first two weeks of life in 15 patients and at seven months in one patient. Left ventricular function significantly decreased during follow-up (14 days to 9.3 years, SF = 9% +/- 5%). Twelve of 16 patients developed congestive heart failure before age 24 months. Myocardial biopsy revealed hypertrophy in 11 patients, interstitial fibrosis in 11 patients, and myocyte degeneration in two patients. Clinical status during follow-up was guarded: four patients died from congestive heart failure; seven required cardiac transplantation; one was awaiting cardiac transplantation; and four exhibited recovery of SF (31 +/- 2%). CONCLUSIONS: Despite early institution of cardiac pacing, some infants with CHB develop LV cardiomyopathy. Patients with CHB require close follow-up not only of their cardiac rate and rhythm, but also ventricular function.

Cardiomyopathy, Dilated↗

PubMed2001

Melanoma cells stimulate osteoclastogenesis, c-Src expression and osteoblast cytokines.

Malignant melanomas metastasise to the bone and enhance osteoclast bone resorption. We demonstrated that a 48-h-B16 melanoma cell conditioned media (B16CM) induced osteoclastogenesis in mouse bone marrow cultures, without the requirement of B16 cell-bone marrow cell co-culture. B16 cells transcriptionally expressed detectable levels of TGFbeta1, IL-6, M-CSF, GM-CSF and TNFalpha mRNAs, albeit to a lower extent compared with levels in osteoblasts, and failed to express PTHrP, OPGL, OPG and IL-1beta. Interestingly, B16CM greatly upregulated IL-1beta, IL-6 and GM-CSF, and modestly enhanced TNFalpha and OPGL mRNA expression in osteoblasts, suggesting a potential indirect stimulation of osteoclastogenesis via the osteogenic lineage. B16CM barely upregulated c-Fos, but strongly and time-dependently enhanced c-Src expression in the total bone marrow cultures during osteoclast differentiation. Moreover, c-Src expression was enhanced in differentiated and purified osteoclast preparations to higher levels than in stromal cells. In conclusion, melanoma induces osteoclast generation with a paracrine mechanism independent of cell-cell contact, specifically upregulating c-Src in osteoclasts and cytokine expression in osteoblasts.

Animals↗

PubMed2001

Serum insulin-like growth factor binding proteins (IGFBPs) as markers for anabolic/catabolic condition in fishes.

In fishes as well as in all vertebrates in which it has been assessed, physiological shifts toward catabolism (e.g. such as during food deprivation) are consistently associated with elevations in the serum levels of at least one (often two in fishes) IGFBP in the < or =31-kDa size range. In mammals, 30-kDa IGFBP-1 is strongly up-regulated under catabolic circumstances, and it plays an important physiological role by sequestering IGF peptides to inhibit energy-expensive growth until conditions are more favorable (e.g. with resumed feeding). Similarly in fishes, it has been found that when the < or =31-kDa IGFBPs are elevated in serum, somatic growth is inhibited, suggesting a similar growth-inhibitory role of these proteins to that of mammalian IGFBP-1. Three different experimentally-induced catabolic states in fishes are compared in this paper: fasting; insulin-dependent diabetes mellitus (IDDM); and stress. A strong relationship between elevated serum cortisol concentrations and the presence of IGFBPs in each case is noted, and the utility of serum IGFBP measurement to serve as an effective indicator (marker) of catabolic condition in fishes is discussed.

Animals↗

PubMed2001

Patterns of hemispheric perceptual asymmetries: left hemispatial biases predict changes in anxiety and positive affect in undergraduate women.

Consistent with the tripartite model of anxiety and depression, hemispheric asymmetries may be differentially associated with depressive and anxious symptoms. Indeed, research has demonstrated that asymmetries do exist when examining hemispatial biases in both anxious and depressed individuals; however, the magnitude and direction of these asymmetries has been variable. The Chimeric Faces Task was used here to measure these asymmetries, along with measures for current and future levels of anxiety and depression. Results indicated that (a) increased left hemispatial biases at Time 1 predict increased anxiety (i.e., physiological hyperarousal) at Time 2 among female undergraduate students and (b) decreased left hemispatial biases at Time 1 predict decreased positive affectivity at Time 2 among the same participants. The possibility that hemispatial biases represent a vulnerability to future anxiety and depression is discussed.

Adolescent↗

PubMed2001

Bowel management with antegrade colonic enema using a Malone or a Monti conduit--clinical results.

During this last decade, major surgical improvements have been proposed for the treatment of patients suffering from faecal incontinence or intractable constipation. Between 1996 and 1999, 12 patients mainly presenting with spina bifida were operated for antegrade colonic enema (ACE). In seven cases, a Malone procedure was performed. In 5 cases we used a Monti plasty to create a continent catheterisable conduit. In 4 cases the neoconduit was placed between the transverse colon and the umbilicus. The mean follow-up was 15 months. Bowel control and continence were obtained in 11 cases, postoperatively. One early complete stenosis of the cutaneous stoma occurred, after which the patient did not wish to carry on. Another patient stopped using his ACE stoma after several months because he was able to manage his bowel evacuation voluntarily without requiring an enema. The other ten patients have greatly improved their quality of life. Complications included principally stomal stenosis which can be regularly dilated by the patient himself using the Hegar dilator. Patients with umbilical stoma have a result comparable to patients with Malone procedure. Our series shows that ACE can be performed without an appendix using a Monti plasty. Implantation of the continent conduit in the caecum or in the transverse colon does not modify the overall results of ACE.

Adolescent↗

PubMed2001

Very-large-volume sampling of water in gas chromatography using the through oven transfer adsorption desorption (TOTAD) interface for pesticide-residue analysis.

The Through Oven Transfer Adsorption Desorption (TOTAD) interface is used to directly introduce large volumes of water (1 mL or more) into a capillary gas chromatograph. The TOTAD interface is a greatly modified programmed temperature vaporizer injector incorporating changes that affect the pneumatics, sample introduction, solvent elimination, and operation mode. The system can easily be automated. The technique is applied to the analysis of pesticide residue in standard solutions and real water samples from the Ebro River (northeastern Spain). The speed of sample introduction was 1 mL/min, and the solvent elimination was almost complete. A nitrogen phosphorous detector is used, and the relative standard deviation varied from 5.7% to 11.7% for the absolute peak areas. The sensitivity achieved by introducing 1 mL of the sample is sufficient for most pesticide-residue analyses in water. The limits of detection ranged from 0.5 to 8.1 ng/L.

Chromatography, Gas↗

PubMed2001

Molecular and antigenic comparison of Ehrlichia canis isolates from dogs, ticks, and a human in Venezuela.

We previously culture isolated a strain of Ehrlichia canis, the causative agent of canine ehrlichiosis, from a human in Venezuela. In the present study, we examined whether dogs and ticks are infected with E. canis in Venezuela and, if so, whether this is the same strain as the human isolate. PCR analysis using E. canis-specific primers revealed that 17 of the 55 dog blood samples (31%) and all three pools of four Rhipicephalus sanguineus ticks each were positive. An ehrlichial agent (Venezuelan dog Ehrlichia [VDE]) was isolated and propagated in cell culture from one dog sample and was further analyzed to determine its molecular and antigenic characteristics. The 16S rRNA 1,408-bp sequence of the new VDE isolate was identical to that of the previously reported Venezuelan human Ehrlichia isolate (VHE) and was closely related (99.9%) to that of E. canis Oklahoma. The 5' (333-bp) and 3' (653-bp) sequences of the variable regions of the 16S rRNA genes from six additional E. canis-positive dog blood specimens and from three pooled-tick specimens were also identical to those of VHE. Western blot analysis of serum samples from three dogs infected with VDE by using several ehrlichial antigens revealed that the antigenic profile of the VDE was similar to the profiles of VHE and E. canis Oklahoma. Identical 16S rRNA gene sequences among ehrlichial organisms from dogs, ticks, and a human in the same geographic region in Venezuela and similar antigenic profiles between the dog and human isolates suggest that dogs serve as a reservoir of human E. canis infection and that R. sanguineus, which occasionally bites humans residing or traveling in this region, serves as a vector. This is the first report of culture isolation and antigenic characterization of an ehrlichial agent from a dog in South America, as well as the first molecular characterization of E. canis directly from naturally infected ticks.

Animals↗

PubMed2001

N-terminal domain of Borna disease virus G (p56) protein is sufficient for virus receptor recognition and cell entry.

Borna disease virus (BDV) surface glycoprotein (GP) (p56) has a predicted molecular mass of 56 kDa. Due to extensive posttranslational glycosylation the protein migrates as a polypeptide of 84 kDa (gp84). The processing of gp84 by the cellular protease furin generates gp43, which corresponds to the C-terminal part of gp84. Both gp84 and gp43 have been implicated in viral entry involving receptor-mediated endocytosis and pH-dependent fusion. We have investigated the domains of BDV p56 involved in virus entry. For this, we used a pseudotype approach based on a recently developed recombinant vesicular stomatitis virus (VSV) in which the gene for green fluorescent protein was substituted for the VSV G protein gene (VSV Delta G*). Complementation of VSV Delta G* with BDV p56 resulted in infectious VSV Delta G* pseudotypes that contained both BDV gp84 and gp43. BDV-VSV chimeric GPs that contained the N-terminal 244 amino acids of BDV p56 and amino acids 421 to 511 of VSV G protein were efficiently incorporated into VSV Delta G* particles, and the resulting pseudotype virions were neutralized by BDV-specific antiserum. These findings indicate that the N-terminal part of BDV p56 is sufficient for receptor recognition and virus entry.

Animals↗

PubMed2001

Detection of aflatoxin-contaminated grain by three granivorous bird species.

Supplemental feeding of game species and the use of backyard feeders to attract avian wildlife are common practices throughout the United States. However, these activities may expose wildlife to aflatoxins. We tested the hypothesis that wild birds would avoid consuming aflatoxin-contaminated feed. Individual northern bobwhites (Colinus virginianus), white-winged doves (Zenaida asiatica), and green jays (Cyanocorax yncas) were presented with feeders that had four compartments, which contained milo that was contaminated with aflatoxin levels of 0, 100, 500, and 1,000 microg/kg, respectively. Feed remaining was weighed at 6, 12, 18, 24, 36, 48, 60, and 72 hr after the initiation of the trial. White-winged doves and northern bobwhites did not avoid contaminated feed. However, green jays selected against aflatoxin-tainted grain. Because white-winged doves and northern bobwhites did not avoid contaminated feed, the risk of exposure to this potentially hazardous toxin exists for these species.

Aflatoxins↗

PubMed2001

The interpersonal consequences of inflated self-esteem in an inpatient psychiatric youth sample.

This study tested R. F. Baumeister, L. Smart, and J. M. Boden's (1996) theory of inflated self-esteem with an inpatient psychiatric youth sample. Participants were assessed on their self-reported self-esteem, self-reported interpersonal problems, and peer rejection (measured by evaluations from 3 or 4 peers). Consistent with the hypotheses, those with low self-esteem reported the most interpersonal problems, followed consecutively by the moderate self-esteem group and then the high self-esteem group, who reported the fewest interpersonal problems. Also in line with the hypotheses, those with low and high self-esteem were rejected by their peers when compared with the moderate self-esteem group. Thus, the high self-esteem group was rejected by their peers but did not themselves report interpersonal problems. These findings provide further support for Baumeister et al.'s theory and generalize the theory to a clinical setting.

Adolescent↗

PubMed2000

A mutation in the DE loop of the VP1 protein that prevents polyomavirus transcription and replication.

Natural mutants of the DE loop of the Polyomavirus (Py) major coat protein VP1 have been previously shown to display an altered host specificity (L. Ricci, R. Maione, C. Passananti, A. Felsani, and P. Amati, 1992, J. Virol. 66, 7153-7158). To better understand the role of this outfacing loop of the VP1 protein in Py infectivity, we constructed and characterized a Py mutant (Py M17) harboring a deletion of 7 AA within the tip of the DE loop. The mutant virions obtained after DNA transfection were unable to replicate and initiate early transcription in fibroblast cells. Complementation experiments performed to rescue the deficient M17 replication by means of wt functions revealed the cis-dominance of the mutation. In situ cell fractionation experiments demonstrated that the Py mutant, like the Py wt, enters the cells, reaches the nucleus and that both the viral DNA and VP1 protein are found tightly bound to the nuclear matrix. These data suggest that the VP1 protein, associated to the viral DNA, conditions early viral gene expression and that the DE loop of the protein must be involved in this process.

3T3 Cells↗

PubMed2000

Zolmitriptan stimulates a Ca(2+)-dependent K(+) current in C6 glioma cells stably expressing recombinant human 5-HT(1B) receptors.

Stimulation of a Ca(2+)-dependent K(+) current by zolmitriptan, a 5-HT(1B/1D) receptor partial agonist, was investigated in C6 glioma cells stably expressing recombinant human 5-HT(1B) receptors. Outward K(+) currents (I(K)) were examined in non-transfected C6 glioma cells and in cells expressing cloned human 5-HT(1B) receptors using the patch-clamp technique in the whole-cell configuration. In C6 glioma cells expressing recombinant human 5-HT(1B) receptor, zolmitriptan increased I(K) in a concentration-dependent manner (maximum increase 16.3+/-7.8%, n=5, p<0.001) with a pD(2) value (geometric mean with 95% confidence intervals) of 7.03 (7.90-6.10). Zolmitriptan failed to elicit increases in I(K) in non-transfected C6 cells. In the presence of the mixed 5-HT(1B/1D) receptor antagonist, N-[4-methoxy-3-(4-methyl-1-piperazinyl)phenyl]-2(-methyl-4(5-methyl-1 ,2,4)-oxadiazol-3-yl)[1,1-biphenyl]-4-carboxamide 2HCl (GR 127935, 0. 1 mcM), zolmitriptan (1 mcM) failed to significantly increase I(K) in C6 cells expressing human 5-HT(1B) receptors confirming that zolmitriptan-evoked responses were indeed mediated by human 5-HT(1B) receptors. In C6 cells expressing cloned human 5-HT(1B) receptors, zolmitriptan-induced increases in I(K) were prevented by the calcium chelator, EGTA (5 mM) when included in the patch pipette (maximum increase -3.3+/-4.2%, n=4, P=NS). The Ca(2+)-dependent K(+) channel blockers, iberiotoxin (0.1 mcM) and tetraethylammonium (TEA, 1 mM), abolished zolmitriptan-induced increases in I(K) (4.5+/-7.3%, n=4 and -0.8+/-1.7%, n=4, respectively, P=NS in each case) in C6 cells expressing human 5-HT(1B) receptors, confirming the involvement of Ca(2+)-dependent K(+) channels. In conclusion, the 5-HT(1B/1D) receptor partial agonist, zolmitriptan, stimulates I(K/Ca) in C6 glioma cells stably transfected with human 5-HT(1B) receptors suggesting an increase of hyperpolarizing current.

Animals↗

PubMed2000

Pesticide residue analysis by off-line SPE and on-line reversed-phase LC-GC using the through-oven-transfer adsorption/desorption interface.

A new method to determine pesticide residue in water is presented. The described method includes using off-line solid-phase extraction (SPE) and on-line reversed-phase liquid chromatography-gas chromatography (RPLC-GC). An interface, based on a modified programmed temperature vaporizer (PTV) injector, packed with a suitable trapping material, is used for on-line RPLC-GC. The changes made in the PTV injector affect the pneumatic system, sample introduction, and solvent elimination. The new interface is easily capable of automation. Methanol/wate (70/30) is used as the eluent in the LC preseparation step. The LC column flow during elution is different from the flow during the transfer step. The transferred volumes range from 500 to 1400 microL (volume of the fractions of interest). Solvent elimination is almost 100% before the sample reaches the GC column. The described system does not show any variation of the peak retention times. The detection limit for real samples ranges from 0.04 to 1.5 ng/L, using NP detection.

Adsorption↗

PubMed2000

Microlaparoscopic cholecystectomy. Less invasive gallbladder surgery.

BACKGROUND: We set out to compare a prospective evaluation of microlaparoscopic cholesystectomy (MLC) using 5-mm ports for the scope and operating ports and two 2-mm ports for retracting to the historic results of standard laparoscopic cholecystectomy (SLC). METHODS: Fifty-six consecutive patients were operated electively for symptomatic gallstones between June 1997 and July 1998. Demographics, history of prior abdominal surgery, operative time, resident level, need to convert, length of stay, and postoperative analgesia were recorded for each case. In all, 43 women and 13 men aged 21 to 89 (average, 51 years) underwent MLC. Average weight was 78 kg (range, 48-119) and average height was 163 cm. RESULTS: Operative time for MLC was 72+/-25 min (range, 35-140), somewhat less than the referenced standard of 79+/-27 min (p = 0.1). The skin-to-trocar time (6+/-2 vs. 13+/-77 min) and intraoperative cholangiogram time (9+/-8 vs. 11+/-6 min) were significantly shorter (p<0.01 and p<0.05, respectively) for MLC. Other partial times were not significantly different. PGY2 residents averaged 74+/-21 min (range, 44-118) compared to 75+/-27 min (range, 35-140) for PGY3 and 53+/-5 (range, 43-59) for PGY5. Patient weight influenced time. Patients <65 kg averaged 56 +/-12 min; 66-80 kg, 72+/-24 min; 81-95 kg, 78+/-26 min; and >95 kg, 85+/-22 min. Previous abdominal surgery did not affect operative time. Nine patients (16%) required conversion from 2- to 5-mm ports because of adhesions, wall thickening, or need for better retraction. Time in these patients was 95+/-26 min vs. 68+/-21 min in other patients (p<0.01). No patient was converted to an open procedure. Three patients (5%) had a positive cholangiogram and common bile duct exploration that required placement of an extra 5-mm trocar. Five patients (9%) required insertion of an additional 2-mm port. All patients received patient-controlled analgesia (PCA). Morphine use was 0.21+/-0.19 mg/kg (range, 0-0.8). Hospital stay was 1.31 days (range, 0.5-4). Subjective satisfaction was excellent because of smaller incisions. No additional morbidity was seen with MLC. CONCLUSION: MLC is a feasible and safe approach that provides similar times to SLC with better cosmesis, a less painful recovery, and possibly an earlier return to normal activity.

Adult↗

PubMed2000

Search for evidence of a Th2 profile in HIV+ patients.

BACKGROUND: Hypersensitivity dermatoses are common in human immunodeficiency virus-positive (HIV+) patients, particularly as the disease progresses. Studies have shown that a switch to T-helper 2 (Th2) might represent a turning point in HIV. This study investigated whether increases in the number of skin mast cells, immunoglobulin E (IgE) serum levels, and eosinophilia, involved in the Th2 response in allergic disease, might also be present in HIV+ patients. If so, these alterations might explain one of the mechanisms of skin hypersensitivity in these patients. METHODS: Forty-five skin biopsies from the normal skin of the upper arm of HIV+ patients and 15 controls were included in the study. HIV+ individuals were classified into three equal categories according to their immunologic status: Category I (< 200/microL), Category II (200-499/microL), and Category III (> 500/microL). Anti-tryptase antibody was employed in tissue sections to show mast cells; IgE serum levels and eosinophils in peripheral blood count were investigated; delayed-type hypersensitivity (DTH) skin tests (candidin, trichophytin, and PPD 2U) were evaluated. RESULTS: Normal cutaneous mast cell and eosinophil counts were the same in all categories and in the control group, but increased IgE levels (P < 0. 01) and DTH skin test anergy (P < 0.006) were observed among acquired immunodeficiency syndrome (AIDS) patients. CONCLUSIONS: The density of skin mast cells in HIV infection was not modified in the course of the disease. Mast cells do not seem to be primarily responsible for triggering hypersensitivity dermatoses among AIDS patients, although data in support of the Th2 response, as seen in increased IgE serum levels and DTH anergy, are present.

Adult↗