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Biomedical subjects

M Alvarez

Publications and source records attributed to M Alvarez.

At least 55 records · Page 3Linked to original sources
PubMed2003

National prevalence of larval echinococcosis in sheep in slaughtering plants Ovis aries as an indicator in control programmes in Uruguay.

Diagnostic surveys carried out on ovine larval echinococcosis in slaughtering plants at a national level in 1998 made it possible to meet several objectives, i.e. to estimate the existing levels of prevalence, to evaluate the effectiveness of the control actions applied by the Programme against Hydatidosis and to contribute to the improvement of the health information systems for epidemiological surveillance. The work included sheep (Ovis aries), both lambs (2-4 teeth) and adults (6-8 teeth). A random sample was performed among sheep from the plants that slaughter the majority of animals in the country. The sample included 22 animals per herd, and it involved removing their offal (liver, lungs and heart) and processing serial sections at the laboratory. The histopathological studies were performed on the lesions that could not be adequately identified at gross examination, and those that were so small that had to be submitted for confirmation of the diagnosis. Of the 2035 animals that were examined, 1019 were lambs (2-4 teeth) and 1016 were adults (6-8 teeth). The prevalence of larval echinococcosis was 7.7% in lambs and 18.0% in adults. The overall prevalence in the liver was 8.5 and 8.0% in the lungs. As to the characteristics of the morphologic structures of the larvae, in younger animals 29% of the lesions were calcified, and 71.0% were hyaline, while in older animals the proportions were 34.4% calcified versus 65.6% hyaline. Other conditions found in the liver parenchyma included: white stain (0.8%), caseous lymphadenitis (3.0%), abscess (0.4%), larvae of Taenia hydatigena (5.1%), Fasciola hepatica (3.9%). And 1.7% of the animals presented larvae of Taenia ovis in the cardiac muscle. Previous surveys carried out in 1994 using the same methodology showed a prevalence of 15.2% in 2-4 teethed animals and 33.9% in 6-8 teethed animals, thus confirming that rates have decreased by 49.6 and 47.0%, respectively. The data obtained reflect the reduction of areas contaminated with eggs of Echinococcus granulosus, which would cause a loss in immunity against this parasite after a certain time. Prevalence of larvae T. hydatigena and T. ovis could change if more sites were considered, a fact that was confirmed in studies carried out in our country. The species O. aries must be used as an indicator in the control programmes, especially in the category of 2-4 teethed lambs. The fact they are not as frequent in our market must be considered; in 1998 they accounted for only 3.0% of the total numbers of animals.

Abattoirs↗
PubMed2003

The effects of fish oil, olive oil, oleic acid and linoleic acid on colorectal neoplastic processes.

BACKGROUND AND AIMS: Several nutrients play a significant role in colorectal cancer development, and fats could be among the most determinant. While several studies have shown that the n-3 fatty acids eicosapentaenoic and docosahexaenoic and its main dietary source, fish oil could exert important antineoplastic effects, much less is known about the effects of olive oil and its main fatty acid, oleic acid, and linoleic acid. The aim of these studies is to assess the role of these nutrients in crucial processes involved in colorectal carcinogenesis. METHODS: Caco-2 and HT-29 colorectal cancer cells were supplemented with different fats and their role in apoptosis induction, cell proliferation, and differentiation was studied. COX-2 and Bcl-2 expressions were also assessed. RESULTS: Supplementation with fish oil or olive oil results in an induction of apoptosis and cell differentiation. The latest effect was also induced by oleic and linoleic acid. Fish oil diminishes significantly cell proliferation. Supplementation with fish oil and olive oil results in an early downregulation of COX-2 followed by a decrease in Bcl-2 expression. CONCLUSIONS: Fish oil and olive oil are capable of influencing crucial processes responsible for colorectal cancer development. COX-2 and Bcl-2 may be important mediators of some of these effects.

Apoptosis↗
PubMed2003

Phosphate and arsenate retention in sediments of the Anllóns river (northwest Spain).

We have studied the distribution and sorption behavior of phosphate and arsenate in bed-sediments of the Anllóns river (NW Spain). As a consequence of the intense gold-mining activity in the past, substantial amounts of arsenic were found in the river sediments. For phosphorus, higher concentrations were found near two sources of P pollution. Sorption isotherms were described by the Freundlich, Langmuir and Tempkin equations. In general, the sediments sorbed more P than As. The equilibrium P concentration (EPC) reveals that sediments act as a scavenger for soluble P; by contrast, equilibrium As concentration (EAC) values were high for the As-rich sediments and correlates well with total arsenic content. Amorphous Fe oxides content, organic matter and fraction of clay plus silt were the main properties of the sediments related with the sorption of arsenate and phosphate. The results obtained provide a first estimate of the sorption behavior and availability of the phosphate and arsenate anions in the sediments of the Anllóns river.

Adsorption↗
PubMed2002

How well do we know atomic motions of simple liquids?

Microscopic motions in molten potassium spanning three frequency decades are studied by neutron-scattering techniques. These comprise well-defined density oscillations and stochastic particle rearrangements and both are modeled on microscopic grounds. While vibratory motions are shown to share characteristics with those of their parent crystals, dynamic correlations between a diffusing particle and its neighbors can be accounted for only semiquantitatively.

Journal Article↗
PubMed2002

The ecology of extinction: molluscan feeding and faunal turnover in the Caribbean Neogene.

Molluscan faunal turnover in the Plio-Pleistocene of the tropical western Atlantic has been attributed to drops in temperature or primary productivity, but these competing hypotheses have not been assessed ecologically. To test these alternatives, we compiled data on changing molluscan life habits and trophic composition over 12 million years derived from 463 newly made collections from the southwestern Caribbean. Shelf ecosystems have altered markedly in trophic structure since the Late Pliocene. Predatory gastropods and suspension-feeding bivalves declined significantly in abundance, but not in diversity, and reef-dwellers became common. By contrast, all other ecological life habits remained remarkably stable. Food-web changes strongly support the hypothesis that declining regional nutrient supply had an increasing impact on regional macroecology, culminating in a faunal turnover.

Animals↗
PubMed2002

Eikenella corrodens brain abscess after repeated periodontal manipulations cured with imipenem and neurosurgery.

Eikenella corrodens is a facultatively anaerobic gram-negative rod that colonizes the oral cavity and very rarely produces central nervous system (CNS) infections. Frontal lobe abscesses are occasionally associated with a dental source of infection. We report a case of an adult man with overzealous dental cleaning habits who developed a right frontal brain abscess caused by E. corrodens. He underwent neurosurgical drainage of the pus and was successfully treated with imipenem 4 g/i.v./day for 4 weeks with no complications. Repeated periodontal trauma could explain the Eikenella brain abscess in this case.

Anti-Bacterial Agents↗
PubMed2002

Osteoblast intracellular localization of Nmp4 proteins.

Nmp4 proteins are transcription factors that contribute to the expression of type I collagen and many of the matrix metalloproteinase genes. Numerous Nmp4 isoforms have been identified. These proteins, all derived from a single gene, have from five to eight Cys(2)His(2) zinc fingers, the arrangement of which directs specific isoforms to nuclear matrix subdomains. Nmp4 isoforms also have an SH3 binding domain, typical of cytoplasmic docking proteins. Although recent evidence indicates that Nmp4 proteins also reside in the osteoblast cytoplasm, whether they localize to specific organelles or structures is not well defined. The intracellular localization of a protein is a determinant of its function and provides insights into its mechanism of action. As a first step toward determining the functional relationship between the cytoplasmic and nuclear Nmp4 compartments, we mapped their location in the osteoblast cytoplasm. Immunocytochemical analysis of osteoblasts demonstrated that Nmp4 antibodies labeled the mitochondria, colocalized with Golgi protein 58K, and lightly stained the cytoplasm. Western analysis using Nmp4 antibodies revealed a complex profile of protein bands in the nuclear, mitochondrial, and cytosolic fractions. Several of these proteins were specific to defined intracellular domains. Consistent with the western analyses, reverse transcription-polymerase chain reaction (RT-PCR) analysis detected previously uncharacterized Nmp4 isoforms. These data necessarily enlarge the known Nmp4 family from nuclear matrix transcription factors to a more widely extended class of intracellular proteins.

3T3 Cells↗
PubMed2002

Predictive value of transvaginal cervical length in triplet pregnancies for spontaneous preterm delivery at < or = 32 weeks.

OBJECTIVE: To establish whether cervical length is a predictor of spontaneous preterm delivery at < or = 32 weeks in triplet pregnancies. METHODS: This was a case-control study of all triplet pregnancies followed with more than three sonographic assessments of cervical length at 4-week intervals from 1995 to 2000. Cervical length in women delivered spontaneously at < or = 32 weeks (cases) was compared with that of the remaining women (controls). Statistical analysis included Fisher's exact test, chi2 test, one-way analysis of variance, logistic regression and receiver operating characteristic (ROC) curve to determine optimal cervical length thresholds for spontaneous preterm delivery at < or = 32 weeks. RESULTS: Of the 58 women included in the study, 17 (29%) delivered spontaneously at < or = 32 weeks. The preterm delivery group had similar demographic and obstetric variables, but a higher rate of cerclage placement (65% vs 17%, p < 0.001) than controls. Mean +/- standard deviation cervical length was significantly shorter among cases than controls at 16-20.0 weeks (3.0 +/- 1.2 vs. 3.9 +/- 0.8 cm, p = 0.01), but not at 20.1-24.0 weeks (3.5 +/- 1.1 vs. 3.8 +/- 1.0 cm, p = 0.76). Logistic regression analysis determined that cervical length at 16-20 weeks had an odds ratio of 0.43 (95% CI = 0.23, 0.80) for the prediction of spontaneous preterm delivery at < or = 32 weeks. ROC curve analysis identified a cervical length of < or = 2.6 cm as the optimal threshold for the prediction of spontaneous preterm delivery at < or = 32 weeks (sensitivity 41%, specificity 92%). CONCLUSIONS: In a population of triplet gestations with a 29% rate of preterm delivery, cervical length at 16-20.0 weeks, but not at 20.1-24.0 weeks, was inversely correlated with the probability of preterm delivery at < or = 32 weeks.

Adult↗
PubMed2002

[Usefulness of olanzapine in the levodopa-induced psychosis in patients with Parkinson's disease].

BACKGROUND: To evaluate the antipsychotic efficacy of olanzapine (OLZ) in patients with Parkinson's disease (PD) and drug-induced psychosis (DIP) and its repercussion on the motor function. METHODS: Ten patients (5 women and 5 men) diagnosed of PD and DIP, aged 67 years (range: 50-81), with PD duration of 11.1 years (range: 6-23), treated chronically with levodopa per day, received a dose of 2.5 or 5.0 mg OLZ daily. Data concerning improvement of psychosis and worsening of motor function was based on Positive And Negative Symptoms Scale (PANSS) and Unified Parkinsons Disease Rating Scale (UPDRS) motor. RESULTS: Psychotic symptoms were improved in all patients. In most of them the improvement was almost total. Seven patients increased levodopa dose on OLZ, but significant worsening of motor function was reported just in one patient. None of the patients had agranulocytosis in the blood monitoring. Two patients presented weight gain. Seven patients improved their cognitive status. CONCLUSIONS: We conclude that OLZ at the doses studied may have efficacy for DIP which appears in PD and does not induce worsening of motor function in most of the patients.

Aged↗
PubMed2001

Distinct behavior of mutant triosephosphate isomerase in hemolysate and in isolated form: molecular basis of enzyme deficiency.

In a Hungarian family with severe decrease in triosephosphate isomerase (TPI) activity, 2 germ line-identical but phenotypically differing compound heterozygote brothers inherited 2 independent (Phe240Leu and Glu145stop codon) mutations. The kinetic, thermodynamic, and associative properties of the recombinant human wild-type and Phe240Leu mutant enzymes were compared with those of TPIs in normal and deficient erythrocyte hemolysates. The specific activity of the recombinant mutant enzyme relative to the wild type was much higher (30%) than expected from the activity (3%) measured in hemolysates. Enhanced attachment of mutant TPI to erythrocyte inside-out vesicles and to microtubules of brain cells was found when the binding was measured with TPIs in hemolysate. In contrast, there was no difference between the binding of the recombinant wild-type and Phe240Leu mutant enzymes. These findings suggest that the missense mutation by itself is not enough to explain the low catalytic activity and "stickiness" of mutant TPI observed in hemolysate. The activity of the mutant TPI is further reduced by its attachment to inside-out vesicles or microtubules. Comparative studies of the hemolysate from a British patient with Glu104Asp homozygosity and with the platelet lysates from the Hungarian family suggest that the microcompartmentation of TPI is not unique for the hemolysates from the Hungarian TPI-deficient brothers. The possible role of cellular components, other than the mutant enzymes, in the distinct behavior of TPI in isolated form versus in hemolysates from the compound heterozygotes and the simple heterozygote family members is discussed.

Adult↗
PubMed2001

Characterization of neutralization epitopes of simian immunodeficiency virus (SIV) recognized by rhesus monoclonal antibodies derived from monkeys infected with an attenuated SIV strain.

A major limitation in the simian immunodeficiency virus (SIV) system has been the lack of reagents with which to identify the antigenic determinants that are responsible for eliciting neutralizing antibody responses in macaques infected with attenuated SIV. Most of our information on SIV neutralization determinants has come from studies with murine monoclonal antibodies (MAbs) produced in response to purified or recombinant SIV envelope proteins or intact SIV-infected cells for relatively short periods of time. While these studies provide some basic information on the potential immunogenic determinants of SIV envelope proteins, it is unclear whether these murine MAbs identify epitopes relevant to antibody responses elicited in monkeys during infection with either wild-type or attenuated SIV strains. To accomplish maximum biological relevance, we developed a reliable method for the production of rhesus monoclonal antibodies. In the present study, we report on the production and characterization of a unique panel of monoclonal antibodies derived from four individual monkeys inoculated with SIV/17E-CL as an attenuated virus strain at a time when protective immunity from pathogenic challenge was evident. Results from these studies identified at least nine binding domains on the surface envelope glycoprotein; these included linear determinants in the V1, V2, cysteine loop (analogous to the V3 loop in human immunodeficiency virus type 1), and C5 regions, as well as conformational epitopes represented by antibodies that bind the C-terminal half of gp120 and those sensitive to defined mutations in the V4 region. More importantly, three groups of antibodies that recognize closely related, conformational epitopes exhibited potent neutralizing activity against the vaccine strain. Identification of the epitopes recognized by these neutralizing antibodies will provide insight into the antigenic determinants responsible for eliciting neutralizing antibodies in vivo that can be used in the design of effective vaccine strategies.

Amino Acid Sequence↗
PubMed2001

Five-chlorodeoxycytidine, a tumor-selective enzyme-driven radiosensitizer, effectively controls five advanced human tumors in nude mice.

PURPOSE: The study's goals were as follows: (1) to extend our past findings with rodent tumors to human tumors in nude mice, (2) to determine if the drug protocol could be simplified so that only CldC and one modulator, tetrahydrouridine (H4U), would be sufficient to obtain efficacy, (3) to determine the levels of deoxycytidine kinase and dCMP deaminase in human tumors, compared to adjacent normal tissue, and (4) to determine the effect of CldC on normal tissue radiation damage to the cervical spinal cord of nude mice. METHODS AND MATERIALS: The five human tumors used were as follows: prostate tumors, PC-3 and H-1579; glioblastoma, SF-295; breast tumor, GI-101; and lung tumor, H-165. The duration of treatment was 3-5 weeks, with drugs administered on Days 1-4 and radiation on Days 3-5 of each week. The biomodulators of CldC were N-(Phosphonacetyl)-L-aspartate (PALA), an inhibitor of aspartyl transcarbamoylase, 5-fluorodeoxycytidine (FdC), resulting in tumor-directed inhibition of thymidylate synthetase, and H4U, an inhibitor of cytidine deaminase. The total dose of focused irradiation of the tumors was usually 45 Gy in 12 fractions. RESULTS: Marked radiosensitization was obtained with CldC and the three modulators. The average days in tumor regrowth delay for X-ray compared to drugs plus X-ray, respectively, were: PC-3 prostate, 42-97; H-1579 prostate, 29-115; glioblastoma, 5-51; breast, 50-80; lung, 32-123. Comparative studies with PC-3 and H-1579 using CldC coadministered with H4U, showed that both PALA and FdC are dispensable, and the protocol can be simplified with equal and possibly heightened efficacy. For example, PC-3 with X-ray and (1) no drugs, (2) CldC plus the three modulators, (3) a high dose of CldC, and (4) escalating doses of CldC resulted in 0/10, 3/9, 5/10, and 6/9 cures, respectively. The tumor regrowth delay data followed a similar pattern. After treating mice only 11/2 weeks with CldC + H4U, 92% of the PC-3 tumor cells were found to possess CldU in their DNA. The great majority of head-and-neck tumors from patient material had markedly higher levels of dC kinase and dCMP deaminase than found in adjacent normal tissue. Physiologic and histologic studies showed that CldC + H4U combined with X-ray, focused on the cervical spinal cord, did not result in damage to that tissue. CONCLUSIONS: 5-CldC coadministered with only H4U is an effective radiosensitizer of human tumors. Ninety-two percent of PC-3 tumor cells have been shown to take up ClUra derived from CldC in their DNA after only 11/2 weeks and 2 weeks of bolus i.p. injections. Enzymatic alterations that make tumors successful have been exploited for a therapeutic advantage. The great electronegativity, coupled with the relatively small Van der Waal radius of the Cl atom, may result in CldC's possessing the dual advantageous properties of FdC on one hand and BrdU and IdU on the other hand. These advantages include autoenhancing the incorporation of CldUTP into DNA by not only overrunning but also inhibiting the formation of competing TTP pools in tumors. A clinical trial is about to begin, with head-and-neck tumors as a first target of CldC radiosensitization.

Animals↗
PubMed2001

Mechanism of syncope in patients with bundle branch block and negative electrophysiological test.

BACKGROUND: In patients with syncope and bundle branch block (BBB), syncope is suspected to be attributable to a paroxysmal atrioventricular (AV) block, but little is known of its mechanism when electrophysiological study is negative. METHODS AND RESULTS: We applied an implantable loop recorder in 52 patients with BBB and negative conventional workup. During a follow-up of 3 to 15 months, syncope recurred in 22 patients (42%), the event being documented in 19 patients after a median of 48 days. The most frequent finding, recorded in 17 patients, was one or more prolonged asystolic pause mainly attributable to AV block; the remaining 2 patients had normal sinus rhythm or sinus tachycardia. The onset of the bradycardic episodes was always sudden but was sometimes preceded by ventricular premature beats. The median duration of the arrhythmic event was 47 seconds. An additional 3 patients developed nonsyncopal persistent III-degree AV block, and 2 patients had presyncope attributable to AV block with asystole. No patients suffered injury attributable to syncopal relapse. CONCLUSIONS: In patients with BBB and negative electrophysiological study, most syncopal recurrences have a homogeneous mechanism that is characterized by prolonged asystolic pauses, mainly attributable to sudden-onset paroxysmal AV block.

Aged↗
PubMed2001

Preparative isolation of lipid inclusions from Rhodococcus opacus and Rhodococcus ruber and identification of granule-associated proteins.

Triacylglycerol granules synthesized and accumulated by Rhodococcus opacus and Rhodococcus ruber were isolated by glycerol density gradient centrifugation. Whereas only one type of granule could be isolated from R. opacus, two types of granules with different specific densities were isolated from R. ruber. Both types of R. ruber granules showed a similar content of triacylglycerols and poly(3-hydroxybutyrate- co-3-hydroxyvalerate), but the protein profiles of both types were significantly different. The granules with the lower specific density were colorless; the granules with the higher specific density had a deep orange pigmentation. Solubilization studies revealed three different groups of granule-associated proteins: (1) unspecifically bound proteins, (2) relatively weakly associated proteins, and (3) proteins that resisted solubilization by treatment with 2 M NaCl, 2% (w/v) Triton X-114, 6 M guanidinium hydrochloride, up to 8% (w/v) SDS, and proteolytic digestion. The strong association of proteins of the last group suggested that these may play a specific role in the synthesis or mobilization of storage lipids or in the structure of the granules. The N-terminal amino acid sequences of the most tightly bound proteins were obtained. Proteins of low molecular weight with striking sequence similarity to the ribosomal protein L7 from various actinomycetes were always copurified with the granules.

Amino Acid Sequence↗
PubMed2001

HPV types and cofactors causing cervical cancer in Peru.

We conducted a hospital-based case-control study in Peru of 198 women with histologically confirmed cervical cancer (173 squamous cell carcinomas and 25 cases of adenocarcinoma/adenosquamous carcinoma) and 196 control women. Information on risk factors was obtained by personal interview. Using PCR-based assays on exfoliated cervical cells and biopsy specimens, HPV DNA was detected in 95.3% of women with squamous cell carcinoma and in 92.0% of women with adenocarcinoma/adenosquamous carcinoma compared with 17.7% in control women. The age-adjusted odds ratio was 116.0 (95% Cl = 48.6-276.0) for squamous cell carcinoma and 51.4 (95% Cl = 11.4-232.0) for adenocarcinoma/adenosquamous carcinoma. The commonest types in women with cervical cancer were HPV 16, 18, 31, 52 and 35. The association with the various HPV types was equally strong for the two most common types (HPV 16 and 18) as for the other less common types. In addition to HPV, long-term use of oral contraceptives and smoking were associated with an increased risk. HPV is the main cause of both squamous cell carcinoma and adenocarcinoma in Peruvian women.

Adenocarcinoma↗
PubMed2001

[Cyclosporiasis: a clinical and epidemiological study in travellers with imported Cyclospora cayetanensis infection].

BACKGROUND: To assess the clinical and epidemiological characteristics of the enteritis produced by Cyclospora cayetanensis. PATIENTS AND METHOD: A microbiological, epidemiological and clinical protocol in travelers to tropical and temperate areas affected by travelers diarrhea (TD). RESULTS: C. cayetanenesis was isolated from 55 patients. 96% of them suffered TD. Persistent diarrhea (> 2 weeks) was present in 69% and weight loss > or = 3 kg in 38%. In 36% of cases, TD began after returning from the trip. Although C. cayetanensis has a cosmopolitan distribution, it was mostly isolated from travellers to Latin America, the Indian subcontinent and South East Asia. In only five cases a potential risk factor was detected: strawberries (3), buffalo's milk (1) and marinated fish "ceviche" (1). CONCLUSIONS: C. cayetanensis is an emerging enteropathogen, isolated in 2-4% of Spanish travellers suffering from TD, and should be considered in the diferential diagnosis of this clinical entity.

Cyclosporiasis↗