Biomedical subjects

L Mendez

Publications and source records attributed to L Mendez.

At least 19 recordsLinked to original sources

PubMed2003

Optimization and application of SPME for the gas chromatographic determination of endosulfan and its major metabolites in the ng L(-1) range in aqueous solutions.

In the present study an analytical method was optimized for the determination of alpha-endosulfan, beta-endosulfan, endosulfan sulfate, endosulfan ether and endosulfan lactone in small volumes of environmental aqueous samples using solid-phase microextraction (SPME) and gas chromatography-electron capture detection (GC-ECD). A 100 micro m polydimethylsiloxane (PDMS) phase was used for the extraction. The limit of detection (LOD) for the analytes varied between 0.01 and 0.03 micro g L(-1) with a relative standard deviation of 3 to 11%. The influence of the ionic strength on the extraction efficiency was investigated for the individual compounds. alpha-Endosulfan, beta-endosulfan, endosulfan sulfate and endosulfan ether were extracted successfully without salt addition. The extraction efficiency of endosulfan lactone was improved with 30% NaCl content. A general decrease in extraction efficiency for alpha-endosulfan, beta-endosulfan, endosulfan sulfate and endosulfan ether with high NaCl content (20-30%) in the solution was observed due to glass surface adsorption. No effect of dissolved organic material (DOM) on the extraction efficiency was observed. The extraction coefficients changed between Log K=2.17 and 3.33. A sample from the Antarctic region was analyzed using the optimized GC-ECD/SPME method. To confirm the results obtained for the real sample a GC with a mass spectrometer (MS) was used. Endosulfan sulfate, the most toxic metabolite of endosulfan, was found in the sample at a concentration of 0.3 micro g L(-1).

Antarctic Regions↗

PubMed2003

Quantitative spectral analysis of EEG in psychiatry revisited: drawing signs out of numbers in a clinical setting.

OBJECTIVE: To evaluate the incidence, sensitivity and specificity of abnormal quantitative EEG (QEEG) measures in normal subjects and patients with mental disorders. METHODS: Normalized QEEG measures were blindly assessed in 67 normal human beings and 340 psychiatric patients. QEEG results were correlated to subject condition or diagnosis and magnetic resonance imaging (MRI) findings. RESULTS: QEEG was abnormal in 83% of patients, and 12% of normal subjects. The most frequent abnormality was a decrease in slow (delta and/or theta) bands, either alone, with beta increase, or with alpha decrease, followed by increase in beta band. No normal subject showed delta and/or theta decrease. Slow band decrease was more frequent in depression and mental disorders due to general medical condition, alcohol and drug dependence. However, no pattern was specific of any entity, and patients within the same diagnostic may present different patterns. Delta-theta decrease was correlated with cortical atrophy as seen in MRI. Beta increase was correlated with psychoactive medication. No association was found between any other QEEG pattern and MRI abnormalities, or medication. CONCLUSIONS: Decrease in the delta and theta bands of the QEEG can be regarded as a specific sign of brain dysfunction, and is correlated with cortical atrophy. However, this sign, as other QEEG abnormal patterns, can be found in many different disorders and none of them can be considered as pathognomonic of any specific disorder. SIGNIFICANCE: This work attempted to circumvent the alleged lack of Class I evidence of QEEG utility in the study of psychiatric patients by means of a prospective, blinded study, searching for specific signs of physiopathology in individual patients.

Adolescent↗

PubMed2002

A high statistics measurement of the Lambda(+)(c) lifetime.

A high statistics measurement of the Lambda(+)(c) lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis technique with particular attention to the determination of the systematic uncertainty. The measured value of 204.6 +/- 3.4 (stat) +/- 2.5 (syst) fs from 8034 +/- 122 Lambda(+)(c)-->pK(-)pi(+) decays represents a significant improvement over the present world average.

Journal Article↗

PubMed2002

Search for CP violation in the decays D+--> K(S)pi+ and D+-->K(S)K+.

A high-statistics sample of photoproduced charm from the FOCUS experiment has been used to search for direct CP violation in the decay rates for D+-->K(S)pi+ and D+-->K(S)K+. We have measured the following asymmetry parameters relative to D+-->K-pi+pi+: A(CP)(K(S)pi+) = (-1.6+/-1.5+/-0.9)%, A(CP)(K(S)K+) = (+6.9+/-6.0+/-1.5)%, and A(CP)(K(S)K+) = (+7.1+/-6.1+/-1.2)% relative to D+-->K(S)pi+. We have also measured the relative branching ratios and found Gamma(D+-->K(0)pi+)/Gamma(D+-->K-pi+pi+) = (30.60+/-0.46+/-0.32)%, Gamma(D+-->K(0)K+)/Gamma(D+-->K-pi+pi+) = (6.04+/-0.35+/-0.30)%, and Gamma(D+-->K(0)K+)/Gamma(D+-->K(0)pi+) = (19.96+/-1.19+/-0.96)%.

Journal Article↗

PubMed2001

Measurement of the branching ratios of D(+) and D(+)(s) hadronic decays to four-body final states containing a K(S).

We have studied hadronic four-body decays of D(+) and D(+)(s) mesons with a K(S) in the final state using data recorded during the 1996-1997 fixed-target run of the Fermilab high energy photoproduction experiment FOCUS. We report a new branching ratio measurement of gamma(D(+)-->K(S)K-pi(+)pi(+))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0768+/-0.0041+/-0.0032. We make the first observation of three new decay modes with branching ratios gamma(D(+)-->K(S)K+pi(+)pi(-))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0562+/-0.0039+/-0.0040, gamma(D(+)-->K(S)K+K-pi(+))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0077+/-0.0015+/-0.0009, and gamma(D(+)(s)-->K(S)K+pi(+)pi(-))/gamma(D(+)(s)-->K(S)K-pi(+)pi(+)) = 0.586+/-0.052+/-0.043, where in each case the first error is statistical and the second error is systematic.

Journal Article↗

PubMed2001

Study of the decay D0 --> K+pi-.

Using a large sample of photoproduced charm mesons from the FOCUS experiment at Fermilab (FNAL-E831), we observe the decay D0-->K+pi- with a signal yield of 149+/-31 events compared to a similarly cut sample consisting of 36 760+/-195 D0-->K-pi+ events. We use the observed ratio of D0-->K+pi- to D0-->K-pi+ (0.404+/-0.085+/-0.025)% to obtain a relationship between the D0 mixing and doubly Cabibbo suppressed decay parameters.

Journal Article↗

PubMed2000

Antitumor activity of a novel glyco-nitric oxide conjugate in ovarian carcinoma.

BACKGROUND: Several studies have shown that nitric oxide (NO)-releasing agents can kill tumor cells. Unfortunately, currently available NO delivery molecules do not target tumor cells preferentially. To exploit the overexpression of glucose transport proteins and the high level of glucose transport characteristics of tumor cells, glucose was conjugated to S-nitroso-N-acetyl-penicillamine (2-gluSNAP) and evaluated for cytotoxicity in human ovarian carcinoma cells. METHODS: The cytotoxicity of 2-gluSNAP and SNAP was assessed by clonogenic cell survival assays performed in A2780S (cisplatin sensitive) and A2780cP (cisplatin-resistant) ovarian carcinoma cells in vitro. Immunoblotting and immunohistochemistry were used to assess the expression of Glut-1 hexose transport protein in the cell lines as well as in paraffin blocks from 28 surgical specimens of epithelial ovarian carcinoma. Apoptosis was assessed by an end-labeling assay. RESULTS: The ovarian carcinoma cell lines consistently were more sensitive to 2-gluSNAP than SNAP alone. The median effective doses (MEDs) for 2-gluSNAP and SNAP in the A2780s cell line were 0.0042 microM and 20.4 microM, respectively. Therefore, 2-GluSNAP was nearly 5000-fold more potent than the NO-donating moiety (SNAP) alone. In the A2780cP cells, the MED for 2-gluSNAP (0.38 microM) was 250-fold lower than that for SNAP alone (100 microM). Immunoblotting and immunohistochemistry studies showed overexpression of Glut-1 in the cell lines and in 23 of 28 epithelial ovarian carcinoma specimens. CONCLUSIONS: The novel glyco-NO conjugate 2-gluSNAP exhibits a much greater cytotoxicity than the parent NO donor without the hexose moiety. These agents have the potential to target tumor cells preferentially, that overexpress Glut-1. This transporter is expressed highly in epithelial ovarian carcinoma.

Drug Screening Assays, Antitumor↗

PubMed2000

Low colorectal anastomosis after radical pelvic surgery: a risk factor analysis.

OBJECTIVE: This study was conducted to analyze our experience with low (8-12 cm above the anal verge) and very low (<6 cm above the anal verge) colorectal resection and primary anastomosis at the time of radical en bloc resection of pelvic malignancies. STUDY DESIGN: A retrospective review of 77 patients undergoing supralevator pelvic exenteration with low colorectal resection and primary anastomosis in our gynecologic oncology service was carried out. Data were obtained from patient medical records and from the tumor registry. Univariate statistical analysis of the data was used. RESULTS: The distribution of primary malignancies in this cohort was as follows: 33 (43%) recurrent or primary cervical carcinomas, 27 (35%) primary or recurrent ovarian carcinomas, 7 (9%) recurrent vaginal carcinomas, 4 (5%) endometrial carcinomas, 3 (4%) colon carcinomas, and 3 (4%) cases of stage IV endometriosis. Forty patients underwent total pelvic exenteration, and 37 patients underwent posterior exenteration. Thirty-six patients in the total pelvic exenteration group had a history of pelvic irradiation. Twelve (30%) of these patients had development of breakdown or fistulas of the anastomosis. Six of the 12 patients (50%) had undergone protective colostomy. Thirty-seven patients underwent posterior exenteration with primary anastomosis for ovarian cancer, endometrial cancer, colon cancer, or endometriosis, and only 1 of these had received pelvic irradiation. This patient did not have a protective colostomy, and a rectovaginal fistula developed. In addition, there were 3 other breakdowns in the posterior exenteration group. Finally, the presence of preoperative ascites did not appear to alter the breakdown rate of the anastomosis among the patients with ovarian cancer who underwent cytoreductive surgery. CONCLUSION: Radical resection of pelvic tissue remains a crucial part of the armamentarium of the gynecologic oncologist. Previous pelvic irradiation appears to be a major risk factor (35% vs 7.5%) for anastomotic breakdown and fistulas, independent of the presence of a protective colostomy. The overall results appear to be better for patients undergoing this procedure as part of a posterior exenteration.

Anastomosis, Surgical↗

PubMed2000

Hyperfractionated radiotherapy concomitant with cisplatin and granulocyte colony-stimulating factor (filgrastim) for laryngeal carcinoma.

An open-label, non-randomized study evaluated the feasibility and efficacy of filgrastim (recombinant methionyl human granulocyte colony-stimulating factor, r-metHuG-CSF) to prevent mucositis induced by accelerated hyperfractionated radiotherapy (1.6 Gy b.i.d., total dose 67.2 Gy in six weeks with a two-week split) and concomitant chemotherapy (cisplatin, 20 mg/m2/day, days 1-5 by continuous intravenous infusion) in patients with laryngeal carcinoma. Filgrastim 300 microg/day was administered on days 1, 3, and 5 in weeks 2-6 of radiotherapy, after the second fraction. Twenty patients (three stage II, six stage III, and eleven stage IV, according to AJCC) were enrolled in the trial. Oral mucosal toxicity was grade 2 in nine patients (45%), grade 3 in eight (40%), and grade 4 in three (15%). Severe hematological toxicity (WHO criteria) was uncommon. Nineteen patients (95%) completed the treatment in the planned time. Overall survival was 55% at three years. The administration of filgrastim with this regimen was feasible, and it appeared to reduce the severity and duration of mucositis induced by the combined treatment.

Adult↗

PubMed1999

Age-related loss of proliferative activity of human vascular smooth muscle cells in culture.

This work studied the proliferation activity in cultures of vascular smooth muscle cells (SMC) from individuals of different ages. The cells derived from arteries of 12 donors of both sexes from 45 to 91 years of age. The main parameter considered was the 'proliferation rate' (cells grown per day in the different culture passages) taking into account the age of the donor. No significant relationship between age of the donor and the cell life in proliferation was found. On the contrary, the mean time of passage duration for reaching the maximum of proliferation as well as its 'efficiency' (maximum of proliferation rate registered/mean time of passage duration) show a statistically significant dependence on the age of the donor. Furthermore, the proliferation rate measured in each passage is statistically significant related to donor age. The regressions obtained show a similar negative slope (VC 4%). Considering the first five culture passages, the regression crosses the x-axis at the age of 105.6+/-11.7 years. This age in which no proliferative activity of human SMC would be expected lies near the limit of maximum life potential for human beings. Our results suggest that with advancing donor age there is an increasing number of senescent SMC either primarily transferred or appeared in the culture. Vascular SMC of individuals whose life is near the end would almost be all senescent and therefore show extremely low proliferation rates in the culture. If the proliferative activity of arterial SMC is a condition for atherogenesis, the proportion of senescent cells would be inversely related to the propensity of developing the atheroma because of the inability of these cells to divide.

Aged↗

PubMed1998

Abdominal pregnancy: to remove or not to remove the placenta.

Objective: The deleterious effect of abdominal pregnancy on the mother and fetus is in part related to the morbidity of the surgical interventions utilized in its treatment. The purpose of this study is to review outcome in abdominal pregnancy after surgical intervention.Study Design: Charts of patients diagnosed with abdominal pregnancy at our institution between 1984 and 1997 were reviewed. The identified cases were categorized as group I, placenta removed at surgery (n = 10), and group II, placenta left in situ (n = 4). Gestational age, maternal death, duration of hospital stay, blood transfusions, organ excisions, and postoperative readmissions were recorded. Student t test was used for statistical analysis with a P <.05 being significant.Results: Fourteen cases were identified ranging from 7 to 36 weeks of gestation. The diagnosis was made before laparotomy in 6 patients by imaging studies. There were no maternal deaths. Among the 9 in whom placenta was removed, 2 had salpingo-oophorectomy (S-O), 4 had total abdominal hysterectomy and bilateral S-O, and 5 received blood transfusions. One developed DIC requiring massive transfusion after a 7-week placenta was excised from the mesentery. This patient was hospitalized postoperatively for 5 months. In contrast, the 4 patients in whom the placenta was left in situ had neither blood transfusions nor removal of pelvic organs. Their hospital stay was shorter, group II, mean 9 +/- 6 days versus group I, 34 +/- 64 days, P =.0007. This difference was accounted for by the one prolonged hospitalization in group I. No patients in either group were readmitted.Conclusion: The diagnosis of abdominal pregnancy is often not made until laparotomy. Regardless of gestational age, placental excision can cause hemorrhage. Leaving the placenta in situ is potentially less costly and less morbid, and appears to shorten operative time and hospital stay while lowering risk of blood transfusion and of surgical menopause.

Journal Article↗

PubMed1995

Recall of informed consent after endoscopic procedures.

PURPOSE: The aim of this study was to determine if recall of informed consent is affected by the timing of obtaining informed consent before endoscopic procedures. METHODS: Sixty patients scheduled for colonoscopy or esophagogastroduodenoscopy were enrolled in this prospective, randomized study. Each patient received informed consent 24 to 72 hours or immediately before the procedure, and follow-up occurred one to three days postprocedure. RESULTS: There was no statistically significant difference in recall of informed consent or the individual elements of informed consent (indication, risks, benefits, alternatives) between the two groups. CONCLUSION: Recall of informed consent is similar whether consent is obtained immediately or several days before endoscopic procedures.

Amnesia, Retrograde↗

PubMed1995

Thalidomide-resistant HIV-associated aphthae successfully treated with granulocyte colony-stimulating factor.

Thalidomide has been advocated as the treatment of choice for recalcitrant aphthae. We describe the case of patient with HIV infection and extensive aphthae whose condition failed to respond to corticosteroids, cyclosporine, and thalidomide. The patient's course was complicated by colonic aphthae. Rapid and sustained resolution was achieved through treatment with granulocyte colony-stimulating factor, a previously unreported therapeutic option.

Adult↗

PubMed1992

Prevalence of antibodies to hepatitis C virus among patients with cryptogenic chronic hepatitis and cirrhosis.

Many cases of chronic hepatitis and cirrhosis cannot be attributed to a known cause and are collectively referred to as cryptogenic chronic liver disease. We have evaluated the role of the hepatitis C virus in the pathogenesis of this condition in a retrospective serum analysis for antibody to hepatitis C virus in 129 patients with cryptogenic liver disease. Other causes of chronic hepatitis and cirrhosis were ruled out by clinical, serum biochemical and serological techniques. All 129 patients were HBcAg negative, but 28 (22%) had antibody to HBcAg. Sera were tested by radioimmunoassays using recombinant peptides for antibodies to nonstructural (C100-3 and C33c) and structural regions (C22) of HCV. Among the 129 patients, 61 (47%) had antibody to C100-3, 76 (59%) had antibody to C33c and 74 (57%) had antibody to C22. Seventy-nine (61%) were reactive with at least one and 76 (59%) were reactive with at least two HCV peptides (this is the criterion used for hepatitis C virus antibody reactivity). A proportion of patients with chronic hepatitis and cirrhosis (55 of 91; 60%) similar to that of patients without cirrhosis (21 of 38; 55%) had hepatitis C virus antibody. No significant clinical, serum biochemical or histological differences were noted between the group of patients with hepatitis C virus antibody and those without this antibody reactivity. Thus more than half the patients with cryptogenic chronic liver disease had hepatitis C virus antibody, suggesting that chronic HCV infection plays a major role in the origin of cryptogenic chronic hepatitis and cirrhosis.

Adult↗

PubMed1992

Familial IgA nephropathy associated with bilateral sensorineural deafness.

Alport's syndrome is the most frequent disorder with familial nephritis and deafness, but other types of nephropathy have been occasionally associated with hereditary hearing loss. The familial occurrence of IgA nephropathy has been well documented. We report a family with hereditary, bilateral, sensorineural deafness spanning four generations. Three of five members with deafness had microscopic hematuria. Renal histology of the two deaf members undergoing biopsy showed mesangial glomerulonephritis with mesangial IgA deposits, without ultrastructural abnormalities of the glomerular basement membranes. Familial nephritis with deafness should not be equated with the diagnosis of Alport's syndrome.

Deafness↗

PubMed1991

Swallowing disorders in the elderly.

The classic symptoms of dysphagia, heartburn, and chest pain are the presenting manifestation of oropharyngeal and esophageal disorders in the elderly as well as the young. Several unique conditions, including Zenker's diverticulum and vascular compression of the esophagus, may occur in the elderly. Certain disorders, such as oropharyngeal dysphagia due to neurologic disorder, increase in frequency with age. Treatment approaches are similar in elderly and younger patients, but the potential for adverse drug effects and interaction is greater in the elderly than in the young.

Aged↗

PubMed1991

Fulminant hepatic failure due to acute hepatitis B and delta co-infection: probable bloodborne transmission associated with a spring-loaded fingerstick device.

Fulminant hepatic failure (FHF) due to acute hepatitis B and delta co-infection occurred in a 74-yr-old female, who eventually died. There was no clear-cut epidemiology other than probable bloodborne transmission from a contaminated spring-loaded fingerstick device used for glucose determination, in an outpatient facility. This unusual mode of transmission reiterates the importance of using sterile cleansing and disposal procedures anytime there is a possibility of contamination with blood.

Aged↗

PubMed1989

Seronegative rheumatoid arthritis, rheumatoid factor cross reactive idiotype expression, and hidden rheumatoid factors.

The major rheumatoid factor cross reactive idiotype (RCRI), defined by prototypic monoclonal rheumatoid factors (RFs), is expressed as a dominant idiotype by pokeweed mitogen induced plasma cells obtained from seropositive (RF+) patients with rheumatoid arthritis (RA). Some patients who meet clinical diagnostic criteria for RA set by the American Rheumatism Association fail to express RFs at any time during their clinical course. To determine if seronegative (RF-) patients with RA, so designated by the latex fixation, Rose-Waaler classic binding assays, or a RF enzyme linked immunosorbent assay (ELISA), express the RCRI in the absence of detectable RFs we examined pokeweed mitogen plasma cells from these patients by indirect immunofluorescence. In addition, we used an inhibition ELISA to detect RCRI bearing molecules in the sera of RF- patients with RA. Five of 10 RF- patients with RA had a high prevalence of RCRI+ plasma cells (16-49% of total pokeweed mitogen plasma cells in culture). Six of 20 RF- patients with RA had high serum concentrations of molecules marked by the RCRI, equivalent to 21-110 micrograms/ml of RCRI+ reference monoclonal IgM RF. Four of five patients who expressed the RCRI in high prevalence in pokeweed mitogen plasma cells, also demonstrated high concentrations of RCRI in their sera detected by inhibition ELISA. There was significant concordance of RCRI expression determined by the two different assays. Four RF- patients with RA who expressed RCRI in their whole sera had hidden RFs detected in their 19S and, in one case, 7S serum fraction. Detection of RF related molecules in whole sera by the expression of RCRI in RF- patients with RA identifies a subgroup of RF- patients with RA who possess hidden RFs. Some RF- patients with RA can express the major RCRI in pokeweed mitogen plasma cells and in their sera and therefore are related to patients with prototypic Waldenstrom's macroglobulinaemia, who produce RCRI+ 19S IgM monoclonal RFs.

Adult↗