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Biomedical subjects

A Cruz

Publications and source records attributed to A Cruz.

At least 19 recordsLinked to original sources
PubMed2005

Randomized clinical trial of the effect of intravenous fluid administration on hormonal and renal dysfunction in patients with obstructive jaundice undergoing endoscopic drainage.

BACKGROUND: Renal dysfunction in patients with biliary obstruction is associated with extracellular water depletion. This study examined the effect of preoperative saline infusion before biliary drainage on hormonal and renal functional derangements in patients with obstructive jaundice. METHODS: In a randomized study, 49 patients with malignant obstructive jaundice were investigated at baseline, on the day of drainage, and at 24 h, 72 h and 7 days after internal endoscopic biliary drainage. Patients were randomized to receive (n = 22) or not to receive (n = 27) 3000 ml normal saline intravenously for 24 h before drainage. Variables analysed included extracellular water volume, creatinine clearance, and serum levels of aldosterone, renin, atrial natriuretic peptide (ANP), vasopressin and albumin. RESULTS: Preoperative saline infusion produced a rise in creatinine clearance, diuresis, ANP concentration and extracellular water volume but this did not translate into better recovery of renal function after operation. Drainage produced a fall in creatinine clearance in all patients, but hormonal and renal function had recovered by 2 days after restoration of bile flow, independently of preoperative hydration. CONCLUSION: Fluid administration expands the extracellular water compartment before drainage but fails to improve renal function after drainage. Definitive improvement in endocrine and renal function requires the restoration of bile flow into the duodenum.

Adult↗
PubMed2004

Development and validation of a method for the quantitation of Delta9tetrahydrocannabinol in oral fluid by liquid chromatography electrospray-mass-spectrometry.

Analysis of Delta(9)tetrahydrocannabinol (Delta(9)THC) and its metabolites in biological samples is of great relevance for forensic purposes. In the case of oral fluid (OF), the analysis should determine Delta(9)THC, whereas in urine, it detects the inactive metabolite tetrahydrocannabinol carboxylic acid (THC-COOH). Most laboratories analyze Delta(9)THC in such samples using GC-MS methods, but these procedures are time-consuming and involve unavoidable previous extraction and derivatization. No data is yet available on the application of liquid chromatography-mass-spectrometry to detect Delta(9)THC in oral fluid. We report a validation method in which the Delta(9)THC is isolated from oral fluid by a simple liquid-liquid extraction with hexane and subsequently analyzed by liquid chromatography-mass-spectrometry. The method here reported for the determination of Delta(9)THC in oral fluid only requires 200 microl of sample and achieves limits of detection of 2 ng/ml, and has been used to analyze oral fluid samples collected from current drug users.

Calibration↗
PubMed2004

Theoretical study of the H(2) reaction with a Pt(4) (111) cluster.

The C(s) symmetry reaction of the H(2) molecule on a Pt(4) (111) clusters, has been studied using ab initio multiconfiguration self-consistent field plus extensive multireference configuration interaction variational and perturbative calculations. The H(2) interaction by the vertex and by the base of a tetrahedral Pt(4) cluster were studied in ground and excited triplet and singlet states (closed and open shells), where the reaction curves are obtained through many avoided crossings. The Pt(4) cluster captures and activates the hydrogen molecule; it shows a similar behavior compared with other Pt(n) (n=1,2,3) systems. The Pt(4) cluster in their lowest five open and closed shell electronic states: (3)B(2), (1)B(2), (1)A(1) (3)A(1), (1)A(1), respectively, may capture and dissociate the H(2) molecule without activation barriers for the hydrogen molecule vertex approach. For the threefolded site reaction, i.e., by the base, the situation is different, the hydrogen adsorption presents some barriers. The potential energy minima occur outside and inside the cluster, with strong activation of the H-H bond. In all cases studied, the Pt(4) cluster does not absorb the hydrogen molecule.

Journal Article↗
PubMed2004

Anaerobic/aerobic treatment of colorants present in textile effluents.

The operation of an anaerobic/aerobic process used to degrade the colorants present in textile wastewater is presented. The objective is to produce water that can be reused. Two particular cases were studied: the degradation of a synthetic wastewater containing the colorant disperse blue 79 (DB79) as a model compound and a real textile effluent containing reactive azo dyes. The biodegradation was achieved using a single tank operated as sequencing batch reactor. It was observed that the DB79 was biotransformed to amines in the anaerobic stage decolorizing the wastewater. The amines formed were subsequently mineralized in the aerobic phase. An increase of toxicity was observed in the anaerobic stage due to the amines formation, but the wastewater was detoxified after the aerobic treatment. Removal efficiencies of DB79 around 92% were observed after the treatment. Around 96% of the initial color of the real wastewater was effectively removed. It was observed that the biomass pre-acclimatized to the degradation of DB79 was more effective for the color removal than a freshly inoculum used.

Azo Compounds↗
PubMed2003

Behaviour of Mycobacterium sp. NRRL B-3805 whole cells in aqueous, organic-aqueous and organic media studied by fluorescence microscopy.

The present work aimed at quantifying the viability and morphological changes occurring during the time course of the side-chain cleavage of beta-sitosterol, in aqueous, two-phase organic-aqueous and organic media by free resting cells of Mycobacterium sp. NRRL B-3805. The solvent used was bis(2-ethylhexyl) phthalate (BEHP). A 66.3% reduction in cell viability was observed after 24 h when the cells were incubated in phosphate buffer only, but the percentage of viable cells was constant thereafter. In biphasic systems with BEHP, cell viability was maintained at higher values in the first 48 h, during which complete degradation of substrate was achieved. The availability of oxygen, which should be higher in the biphasic system than in the aqueous system, and of a carbon and energy source, thus seem important for the cells to retain their viability. In biphasic systems, cells tended to shrink and decrease their surface roughness, i.e. to decrease their surface area, possibly as a way to protect themselves from mechanical stress due to the presence of organic-aqueous interfacial forces, which resulted in disaggregation of cell clusters. A method used to visualise BEHP droplets with a standard optical microscope showed that the cells adhered to the surface of the solvent droplets, but no cells were observed inside these. In pure BEHP medium, cells retained their viability level for at least 150 h, independently of a pre-incubation period, which did not seem to induce any adaptation effect. Solvent biocompatibility, higher oxygen availability and reduced interfacial stress could have contributed to this maintenance of viability.

Androstenedione↗
PubMed2002

[Characteristics of acute renal failure in elderly patients admitted to a small town hospital].

We studied the features of acute renal failure (ARF) in elderly patients treated in a hospital, without an intensive care unit, to identify etiological factors and establish adequate preventive measures and treatment. During twelve consecutive months we studied prospectively 99 patients with ARF diagnosed by conventional criteria, an incidence of 1,238 cases per million per year. ARF affected 1.78% of patients admitted to hospital. We analyzed age, sex, serum creatinine, diuresis, etiology, type of ARF, preexisting chronic diseases, treatment, complications and outcome. Preexisting chronic diseases were common, the most frequent being hypertension (54%) and diabetes (39%). Previous treatments for cardiovascular diseases were frequent (angiotensin-renin system blockade 35.4%, diuretics 50.5%). 79% of ARF arose in hospital, 21% outside hospital. ARF was pre-renal in 60%, renal in 31% and post-renal in 9%. 34.7% were caused by volume depletion, 23.4% by low cardiac output and 23.4% by infection. 44.4% of ARF patients had oliguria or anuria latrogenic factors contributed to the ethiology of ARF in 35.3% of patients. Hospital stay was doubled by ARF the presence of ARF and the mortality was 36.4%. The rate was higher in ARF arising in hospital than in ARF acquired before admission. Factors that had a significant influence on the mortality rate were comorbid conditions, oliguroanuria, ARF of renal origin and serum albumin. We conclude that ARF has a high incidence, morbidity and mortality in this elderly population. Volume depletion, associated cardiovascular pathology and pharmacological treatment are important etiological factors in those with ARF outside hospital. Adequate treatment of ARF and avoidance of nephrotoxic medications are necessary in hospital.

Acute Kidney Injury↗
PubMed2001

Superficial disposition of the N-terminal region of the surfactant protein SP-C and the absence of specific SP-B-SP-C interactions in phospholipid bilayers.

A dansylated form of porcine surfactant-associated protein C (Dns-SP-C), bearing a single dansyl group at its N-terminal end, has been used to characterize the lipid-protein and protein-protein interactions of SP-C reconstituted in phospholipid bilayers, using fluorescence spectroscopy. The fluorescence emission spectrum of Dns-SP-C in phospholipid bilayers is similar to the spectrum of dansyl-phosphatidylethanolamine, and indicates that the N-terminal end of the protein is located at the surface of the membranes and is exposed to the aqueous environment. In membranes containing phosphatidylglycerol (PG), the fluorescence of Dns-SP-C shows a 3-fold increase with respect to the fluorescence of phosphatidylcholine (PC), suggesting that electrostatic lipid-protein interactions induce important effects on the structure and disposition of the N-terminal segment of the protein in these membranes. This effect saturates above 20% PG molar content in the bilayers. The parameters for the interaction of Dns-SP-C with PC or PG have been estimated from the changes induced in the fluorescence emission spectrum of the protein. The protein had similar K(d) values for its interaction with the different phospholipids tested, of the order of a few micromolar. Cooling of Dns-SP-C-containing dipalmitoyl PC bilayers to temperatures below the phase transition of the phospholipid produced a progressive blue-shift of the fluorescence emission of the protein. This effect is interpreted as a consequence of the transfer of the N-terminal segment of the protein into less polar environments that originate during protein lateral segregation. This suggests that conformation and interactions of the N-terminal segment of SP-C could be important in regulating the lateral distribution of the protein in surfactant bilayers and monolayers. Potential SP-B-SP-C interactions have been explored by analysing fluorescence resonance energy transfer (RET) from the single tryptophan in porcine SP-B to dansyl in Dns-SP-C. RET has been detected in samples where native SP-B and Dns-SP-C were concurrently reconstituted in PC or PG bilayers. However, the analysis of the dependence of RET on the protein density excluded specific SP-B-Dns-SP-C associations.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2001

Selective labeling of pulmonary surfactant protein SP-C in organic solution.

Pulmonary surfactant protein SP-C has been isolated from porcine lungs and treated with dansyl isothiocyanate in chloroform:methanol 2:1 (v/v) solutions,under conditions optimized to introduce a single dansyl group covalently attached to the N-terminalamine group of the protein without loss of its native thioesther-linked palmitic chains. The resulting derivative Dans-SP-C conserves the secondary structure of native SP-C as well as the ability to promote interfacial adsorption of DPPC suspensions and to affect the thermotropic behavior of DPPC bilayers. This derivative can be used to characterize lipid-protein and protein-protein interactions of a native-like SP-C in lipid/protein complexes.

Animals↗
PubMed2001

The nuclear factor kappa B (NF-kappa B): a potential therapeutic target for estrogen receptor negative breast cancers.

The effect of a kinase inhibitor Go6796 on growth of epidermal growth factor (EGF)-stimulated estrogen receptor negative (ER-) breast cancer cells in vivo and role of nuclear factor kappa B (NF-kappaB) on tumorogenesis have been investigated. This was studied in an animal model by implanting ER- mouse mammary epithelial tumor cells (CSMLO) in syngeneic A-J mice. (i) Local administration of Go6976 an inhibitor of protein kinases C alpha and beta inhibited growth of tumors and caused extensive necrotic degeneration and regression of the tumors without causing any microscopically detectable damage to the vital organs liver and lung. (ii) Stable expression of dominant-negative mutants of the beta subunit (dnIkkbeta) of the inhibitory kappa B (IkappaB) kinase (dnIkk) that selectively blocked activation of NF-kappaB caused loss of tumorigenic potential of CSMLO cells. Stable expression of dnIkkbeta also blocked phorbol 12-myristate 13-acetate (PMA)-induced activation of NF-kappaB and overexpression of cyclin D1, concomitantly with the loss or reduced tumorigenic potential of these cells. Thus, results from in vivo and in vitro experiments strongly suggest the involvement of NF-kappaB in ER- mammary epithelial cell-mediated tumorigenesis. We propose that blocking NF-kappaB activation not only inhibits cell proliferation, but also antagonizes the antiapoptotic role of this transcription factor in ER- breast cancer cells. Thus, NF-kappaB is a potential target for therapy of EGFR family receptor-overexpressing ER- breast cancers.

Animals↗
PubMed2001

Melatonin protects against renal oxidative stress after obstructive jaundice in rats.

The goals of this study were to analyze the renal oxidative status in experimental biliary obstruction and to evaluate the impact of melatonin on renal oxidative stress. Cholestasis was done by double ligature and section of the extra-hepatic biliary duct. Melatonin was injected i.p. (500 microg/kg/day). Malondialdehyde, reduced glutathione, catalase, superoxide dismutase, glutathione reductase, glutathione peroxidase and glutathione transferase were determined in the renal tissue. After biliary obstruction, an increase in malondialdehyde (P<0.0001) and a fall in reduced glutathione (P<0.0001) were seen. Moreover, the scavenger enzyme activity had significantly diminished. After melatonin administration, the malondialdehyde fell significantly (P<0.0001), whereas reduced glutathione showed an important increase (P<0.0001) compared with the ligated bile duct group. Experimental bile duct obstruction was associated to an increase of renal oxidative stress. Treatment with melatonin decreased the renal lipid peroxidation, and both the reduced glutathione as well as the scavenger enzyme activity recovered.

Animals↗
PubMed2001

Epidemiology of HPV infection among Mexican women with normal cervical cytology.

Cervical cancer is caused by human papillomavirus (HPV) and is the most common cancer among Mexican women, but no population-based studies have reported the prevalence and determinants of HPV infection in Mexico. A population-based study was carried out between 1996 and 1999, based on an age-stratified random sample of 1,340 women with normal cytologic diagnoses from 33 municipalities of Morelos State, Mexico. The prevalence of cervical HPV DNA was determined by reverse line blot strip assay to detect 17 cancer-associated and 10 non-cancer-associated HPV types. Two peaks of HPV DNA prevalence were observed. A first peak of 16.7% was observed in the age group under 25 years. HPV DNA prevalence declined to 3.7% in the age group 35-44 years, then increased progressively to 23% among women 65 years and older. Cancer-associated HPV types were the most common in all age groups; non-cancer-associated HPV types were rare in the young and became more common linearly with age. Twenty-four types of HPV were detected; HPV 16, HPV 53, HPV 31 and HPV 18 were the most common, but none was present in more than 1.7% of subjects. The main determinant of infection with both cancer-associated and non-cancer-associated HPV types was the number of sexual partners in all age groups. Less-educated women were at an increased risk of infection with cancer-associated but not with non-cancer-associated HPV types; low socioeconomic status was associated with detection of non-cancer-associated HPV types. Among young women an increasing number of pregnancies was associated with lower HPV detection and among older women low socioeconomic status was related to increased HPV detection, particularly for the age group 35-54 years. Among women with cancer-associated HPV types, there was a higher intensity of polymerase chain reaction signal in younger than in older age groups (p < 0.001). We present additional evidence for the sexually transmitted nature of HPV infection, regardless of age group and HPV type. We confirm previous findings of a second peak of high-risk HPV infections in postmenopausal women, in this case with a clear predominance of cancer-associated HPV types. In populations with this pattern, which can be related to reactivation of latent HPV infections or high previous exposure in older women, screening with HPV testing can have a reduced specificity among older women if proper cut-off points for HPV positivity are not used. Longitudinal studies of immune responses to HPV infection in different age groups are warranted.

Adult↗
PubMed2001

Melatonin versus vitamin E as protective treatment against oxidative stress after extra-hepatic bile duct ligation in rats.

The aims of the present study were first to compare the effects of melatonin and vitamin E on the cholestasis syndrome and their protective effect on liver injury, and second, to evaluate the activity of antioxidant enzymes after treatment with these antioxidant drugs. Cholestasis was achieved in adult male Wistar rats by double ligature and section of the extra-hepatic biliary duct. Hepatic and plasma oxidative stress markers were evaluated by changes in the amount of lipid peroxides, measured as malondialdehyde (MDA) and reduced glutathione (GSH) in plasma and homogenates of hepatic tissue. Serum bilirubin, alkaline phosphatase (AP), and gamma-glutamyl-transpeptidase (GGT) were used to evaluate the severity of cholestasis, and serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were used to evaluate the hepatic injury. Both vitamin E and melatonin were administrated 1 day before and 7 days after bile duct ligation. Acute ligation of the bile duct was accompanied by a significant increased in MDA and a decrease in GSH levels in both plasma and liver, as well as a significant reduction in antioxidant enzymes activities. The overall analysis of both treatments showed that melatonin (500 microg/kg daily) offered significantly better protection against cholestasis and a superior protective effect on hepatic injury than did vitamin E (15 mg/kg daily). Although vitamin E treatment resulted in a reduction of parameters of oxidative stress, the results were significantly better after a much lower daily dose of melatonin. Moreover, melatonin treatment was associated with a significant recovery of antioxidative enzymes. In conclusion, the present paper demonstrates a correlation between the intensity of biliary tract obstruction and increased free radical generation, as well as a direct correlation between the level of oxidative stress and the biochemical markers of liver injury. Melatonin (at a much lower dose than vitamin E) was much more efficient than vitamin E in reducing the negative parameters of cholestasis, the degree of oxidative stress and provided a significantly greater hepatoprotective effect against the liver injury secondary to the acute ligation of the biliary duct.

Animals↗
PubMed2001

Synthesis and hypolipidemic activity of modified side chain alpha-asarone homologues.

A series of homologues of alpha-asarone (1), containing variable size and functionality on the side chain attached to the aromatic ring, has been subjected to a study of structure-activity relationship. For most of the prepared derivatives, either with a carbonyl (8a-8e), a hydroxy group (9a-9e), or with a conjugated double bond (10a-10d), significant effects on serum lipoprotein cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides were displayed. The results showed an enhancement of the hypocholesterolemic activity as the length of the chain is decreased. Theoretical conformational and electrostatic potential analyses of I and olefins 10 suggest unfavorable steric interactions in the bulky superior side-chain homologues as the deactivating biological effect.

Allylbenzene Derivatives↗
PubMed2001

Perinatal management of fetal cardiac anomalies in a specialized obstetric-pediatrics center.

Perinatal teams dealing with fetal heart disease frequently wonder which pregnancies might be terminated, and when delivery should take place in a specialized surrounding. We present a retrospective study of 229 fetuses, in which prenatal ultrasound showed a cardiac anomaly not compatible with a standard maternity ward delivery. One hundred nineteen pregnancies were terminated (group I) while 110 pregnancies led to the birth of a live baby (group II). Pathology in group I was discovered earlier than in group II (24 vs. 29.3 weeks' gestation; p <0.01), and associated malformations or chromosomal anomalies were much more frequent in group I (80/119 vs. 9/110; p <0.001). Among live born babies, three infants with transposition of the great arteries underwent Rashkind atrioseptostomy in the delivery room. With a minimum follow-up of 12 months, 69 children (63%) have undergone surgery. Among 92 survivors (1 child is lost to follow-up), 78 (71%) are asymptomatic and 14 symptomatic. Early prenatal diagnosis of fetal heart anomalies significantly facilitates prenatal work-up and perinatal care. We present the types of pathology having led to termination and define the situations in which children are at risk of perinatal hemodynamic compromise.

Abortion, Eugenic↗
PubMed2001

High prevalence of antibodies to herpes simplex virus type 2 among middle-aged women in Mexico City, Mexico: a population-based study.

BACKGROUND: Herpes simplex virus type 2 (HSV-2) is among the most prevalent sexually transmitted diseases worldwide. In Mexico there is a lack of population-based HSV-2 surveys. GOALS: To determine population-based HSV-2 seroprevalence and risk factors among women in Mexico City. STUDY DESIGN: A random sample of 730 women was identified among the residents of Mexico City. Women ages 25 to 85 years were selected from 3,694 households. Western blot serology testing was conducted on serum samples to determine HSV-2 type-specific serostatus. A structured questionnaire was administered, and multivariate analyses were performed to identify risk factors for HSV-2 seropositivity, which were stratified into two age categories: younger than 50 years of age and 50 years of age or older. RESULTS: The HSV-2 seroprevalence among female participants was 29.8%, with a significant trend of increasing HSV-2 prevalence for each higher level of age (P < 0.001). Female participants had a median age of 46 years and were predominantly monogamous (82.6%). The overall population-based seroprevalence estimated in Mexico City among women was 35.8%. The independent risk factors for HSV-2 seropositivity included a history of two or more sexual partners (odds ratio [OR], 2.2; 95% CI, 1.4-3.4), two or more sexual partners before first pregnancy (OR, 2.3; 95% CI, 1.4-3.7), cohabitation with partner (OR, 2.5; 95% CI, 1.3-4.7), and current vaginal douching (OR, 1.7; 95% CI, 1.2-2.6). CONCLUSIONS: Population-based HSV-2 seroprevalence is endemically high among middle-age women in Mexico City, and clearly is correlated with higher-risk sexual behavior. This elevated HSV-2 seroprevalence may reflect unrecognized HSV-2 transmission throughout life.

Adolescent↗
PubMed2001

A human breast epithelial cell type with stem cell characteristics as target cells for carcinogenesis.

Two types of human breast epithelial cells (HBEC) have been characterized. In contrast to Type II HBEC, which express basal epithelial cell phenotypes, Type I HBEC are deficient in gap junctional intercellular communication and are capable of anchorage-independent growth and of expressing luminal epithelial cell markers, estrogen receptors, and stem cell characteristics (i.e. the ability to differentiate into other cell types and to form budding/ductal organoids on Matrigel). A comparative study of these two types of cells has revealed a high susceptibility of Type I HBEC to immortalization by SV40 large T antigen, although both types of cells are equally capable of acquiring an extended life span (bypassing senescence) after transfection with SV40. The immortalization was accompanied by elevation of a low level of telomerase activity in the parental cells after mid-passage ( approximately 60 cumulative population doubling levels). Thus HBEC do have a low level of telomerase activity, and Type I HBEC with stem cell characteristics are more susceptible to telomerase activation and immortalization, a mechanism which might qualify them as target cells for breast carcinogenesis. The immortalized Type I HBEC can be converted to highly tumorigenic cells by further treatment with X rays (2 Gy x 2) and transfection with a mutated ERBB2 (also known as NEU) oncogene, resulting in the expression of p185(ERBB2) which is tyrosine phosphorylated.

Animals↗
PubMed2001

A therapeutic target for hormone-independent estrogen receptor-positive breast cancers.

BACKGROUND: The action of the steroid hormone estradiol (E2) is mediated via interaction with a specific receptor (ER) that initiates a series of events downstream, leading to the modulation of hormone-responsive genes and cell proliferation. Antihormones also bind, but do not confer the active configuration to ER, thereby, blocking the transmission of E2-ER-initiated signals for cell proliferation. Although these compounds qualify for successful therapy of ER-positive [ER (+)] breast cancer patients, only a fraction of patients responds to antihormone treatment. In this study, the functional status of ER is determined to identify alternative targets for therapy of antihormone-resistant ER (+) breast cancers. METHOD: The interaction of ER with a specific DNA sequence, designated as E2 response element (ERE), was targeted to assess the functional state of ER. ER-ERE complex formation was measured by electrophoretic mobility shift assay (EMSA) and by a newly developed technique, based on the preferential binding of DNA-protein complex to a nitrocellulose membrane (NMBA) that measures both total and functional fraction of ER. RESULTS: The NMBA assay identified functional variants of ER among ER (+) breast cancer cell lines and breast tumor biopsy specimens. ER of (21PT) cells did not bind E2 and these cells were tamoxifen (TAM) resistant. However 21PT cells were sensitive to a calmodulin (CaM) antagonist, W7, that blocked ERE-ER complex formation. CONCLUSIONS: ER variants of the 21PT type were detected among breast cancer biopsy specimens, emphasizing the significance of an alternative therapeutic target for TAM-resistant ER (+) human breast cancers with compounds such as W7.

Adult↗