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Biomedical subjects

P Alvarez

Publications and source records attributed to P Alvarez.

At least 19 recordsLinked to original sources
PubMed2003

Incarcerated groin hernias in adults: presentation and outcome.

Despite universal acceptance of the value of elective hernia repair, many patients present with incarceration or strangulation, which are associated with significant morbidity and mortality. We reviewed 147 patients who underwent emergency surgery for incarcerated groin hernias during a 10-year period in order to analyze the presentation and outcome in our practice. Median age of the patients was 70 years. There were 77 men and 70 women. Femoral hernias were seen in 77 patients and inguinal hernias in 70. Coexisting diseases were found in 82 cases (55.8%). Bowel resection was required in 19 patients (12.9%). The overall and major morbidity rates were 41.5% and 9.6%, respectively. The mortality rate was 3.4%. Longer duration of symptoms, late hospitalization, concomitant diseases, and high ASA class were found to be significant factors linked with unfavorable outcomes. Because of high morbidity and mortality associated with incarceration, elective repair of groin hernias should be done whenever possible.

Adult↗
PubMed2003

Influence of autograft removal on rabbit patellar tendon length.

Twelve adult New Zealand white rabbits were randomly divided into two groups. In group 1, 30% of the central mass of the right patellar tendon was removed. In group 2, 60% was removed. The left knees served as controls. The animals were killed 1 year later. The patella-patellar tendon-tibial tuberosity units of all knees were studied using histological and morphometric analysis. In both groups, the tendons had lengthened. Lengthening average was 2.50 mm in group 1 and 8.17 mm in group 2. In both groups, histology revealed poor alignment of the collagen fibres and high cellularity, although the findings in group 1 were nearer the normal histological pattern. The results suggest that removal of significant portions of the patellar tendon leads to lengthening of the resulting tendon. In clinical practice, it seems prudent to pay attention to the dimensions of the patellar tendon when harvesting a graft.

Animals↗
PubMed2001

Antinociceptive effect of clomipramine in monoarthritic rats as revealed by the paw pressure test and the C-fiber-evoked reflex.

The antinociceptive effect of clomipramine was studied in monoarthritic rats by using the paw pressure test and the C-fiber-evoked reflex. Monoarthritis was produced by intra-articular injection of complete Freund's adjuvant into the tibio-tarsal joint. Joint circumference as well as vocalization threshold to graded paw pressure were evaluated weekly during a 14-week period after the intra-articular injection. At week 8, monoarthritic and vehicle-injected control rats were given either clomipramine or saline and both the paw pressure threshold and inhibition of the C-fiber-evoked reflex response were evaluated. Results showed that (i) 1.5, 3.0, and 6.0 mg/kg, i.v. of clomipramine induced significantly greater dose-dependent antinociception to paw pressure testing in the monoarthritic group, as compared to the control one; and (ii) 0.75, 1.5, 3.0, and 6.0 mg/kg, i.v. of clomipramine exerted significantly higher dose-dependent inhibition of the C-reflex activity in monoarthritic rats than in controls. Results suggest that the higher sensitivity to clomipramine in monoarthritic rats could be related to adaptive changes occurring in monoamine metabolism or in other neurotransmitter systems during chronic pain.

Analgesics↗
PubMed2001

Homogenous catalyzed ozonation of simazine. Effect of Mn(II) and Fe(II).

Simazine, [2-chloro, 4,6-bis(ethylamino)-1,3,5-s-triazine], a common herbicide typically found in surface and ground water was ozonised by using catalytic amounts of Mn(II) and Fe(II). An optimum value for metal concentration was found in the process. Some inhibition of the simazine degradation rate was observed when these metals were added above the optimum concentration. The pH of the reaction media played a significant role in the simazine oxidation rate. Thus, an increase in simazine conversion was observed when the pH was raised from 5 to 9. However, the catalytic effect of added manganese was negligible at the highest pH used in this study (pH 9). The beneficial influence of Fe(II) was also observed when utilising the combination of ozone and hydrogen peroxide. Contrarily, Mn(II) presented a negative influence on simazine conversion when using this oxidation technology.

Catalysis↗
PubMed2001

Multiple overlapping epitopes in the repetitive unit of the shed acute-phase antigen from Trypanosoma cruzi enhance its immunogenic properties.

The repetitive shed acute-phase antigen (SAPA) from Trypanosoma cruzi was thoroughly mapped by SPOT peptides and phage display strategies, showing that a single SAPA repeat is composed of multiple overlapping B-cell epitopes. We propose that this intricate antigenic structure constitutes an alternative device to repetitiveness in order to improve its immunogenicity.

Animals↗
PubMed2001

Epitope mapping of trans-sialidase from Trypanosoma cruzi reveals the presence of several cross-reactive determinants.

Trypanosoma cruzi, the agent of Chagas' disease, expresses trans-sialidase, a unique enzyme activity that enables the parasite to invade host cells by transferring sialyl residues from host glyconjugates to the parasite's surface acceptor molecules. The enzyme is also shed into the surrounding environment, causing apoptosis in cells from the immune system. During infections, an antibody response against the catalytic region of the trans-sialidase that is coincident with the control of the parasitemia and survival of the host is observed. This low-titer humoral response is characterized by its persistence for many years in benznidazole-treated patients. Here we analyzed the antigenic structure of the molecule by phage-displayed peptide combinatorial libraries and SPOT synthesis. Several epitopes were defined and located on the three-dimensional model of the enzyme. Unexpectedly, cross-reaction was found among several epitopes distributed in different locations displaying nonconsensus sequences. This finding was confirmed by the reactivity of three monoclonal antibodies able to recognize non-sequence-related peptides that together constitute the surface surrounding the catalytic site of the enzyme. The presence of cross-reacting epitopes within a single molecule suggests a mechanism developed to avoid a strong humoral response by displaying an undefined target to the immune system.

Amino Acid Sequence↗
PubMed2000

Effects of intraovarian infusion of insulin-like growth factor-I on ovarian follicular function in cattle.

The objective of this study was to determine if increased secretion of intraovarian insulin-like growth factor-I (IGF-I), experimentally induced via minipumps, affects follicular function in cattle. Fourteen cycling Holstein cows were divided equally into two groups: Control, osmotic minipumps (containing vehicle) surgically inserted into each ovary, or IGF-I treated, osmotic minipumps as in Controls but pumping 2.0 microg of recombinant human IGF-I per hr for 7 days. All cows were synchronized with prostaglandin F(2alpha) 0.10) between Control and IGF-I-treated cows during Days 2 to 6 of treatment. IGF-I treatment increased (P<0.05) estradiol concentrations in follicular fluid of small follicles, but had no effect (P<0.10) on estradiol concentrations in follicular fluid of large follicles, or on progesterone, androstenedione, or IGF binding protein concentrations in small or large follicles. We conclude that a 7-day infusion of IGF-I directly into the stroma of the ovary altered follicular growth and follicular fluid estradiol concentrations.

Animals↗
PubMed2000

Radiotoxicity of h-R3 monoclonal antibody labeled with 188Re administered intracerebrally in rats.

Brain tumors are often incurable despite current aggressive treatment modalities. Regional intracerebral administration of labeled monoclonal antibodies (Mabs) can maximize the radioisotope and Mab concentration to tumor sites while reducing systemic toxicity. h-R3 is a humanized antiepidermal growth factor receptor Mab that successfully targets the epidermal growth factor receptor, which is overexpressed in glioblastomas. We studied the acute local and systemic toxicity effects of intraventricular 188Re-h-R3 in rats. Forty rats were distributed into four groups with five animals of each sex in each group. A single 5 -microl dose (2.5 microl into the left and 2.5 microl into the right lateral ventricles) of neutral solution containing 50 microg of h- R3 labeled with 49.5 +/- 1.7,284 +/- 13.7 or 579 +/- 23.7 muCi of 188Re were stereotactically administered to each animal. Control animals received vehicle alone. Each animal was observed twice daily for detection of toxicity signs. Body weights were recorded on days 0, 7 and 14. Blood samples for analysis of hematological and clinical chemistry parameters were taken on days 0 and 14. Necropsy and histopathological studies were carried out after completion of the study. All animals, but one, remained clinically stable. Toxicities included local radionecrosis, discrete increase in ALAT and creatinine blood values at higher dose level. We concluded that a single intraventricular administration of relatively large doses of 188Re-h-R3 is tolerable and causes minimal local and systemic toxicity effects in rats. Nevertheless, further studies are necessary to discard learning and behavioral problems.

Adenocarcinoma↗
PubMed2000

Ovarian and endocrine characteristics during an estrous cycle in Angus, Brahman, and Senepol cows in a subtropical environment.

To determine breed differences in ovarian function and endocrine secretion, daily rectal ultrasonography was conducted on multiparous lactating Angus (temperate Bos taurus; n = 12), Brahman (tropical Bos indicus; n = 12), and Senepol (tropical Bos taurus; n = 12) cows during an estrous cycle in summer. Blood was collected daily to quantify plasma concentrations of FSH, LH, progesterone, estradiol, GH, insulin-like growth factor (IGF)-I, IGF-II, IGF binding proteins (IGFBP), insulin, glucose, and plasma urea nitrogen (PUN). Numbers of small (2 to 5 mm), medium (6 to 8 mm), and large follicles (> or = 9 mm) were greater (P < .05) in Brahman than in Angus and(or) Senepol cows. Length of the estrous cycle (SEM = .6 d) was similar (P > .10) among Senepol (20.4 d), Angus (19.5 d), and Brahman (19.7 d) cows. Senepol cows had greater (P < .05) diameters of the corpus luteum (CL) and a delayed regression of the CL as compared with Angus cows. The secondary surge of FSH (between d 1 and 2; d 0 = estrus) was greater in Angus than Brahman or Senepol cows (breed x day, P < .05). Between d 2 and 14 of the estrous cycle, concentrations of progesterone, LH, IGF-II, and binding activities of IGFBP-3, IGFBP-2, and the 27- to 29-kDa IGFBP in plasma did not differ (P > .10) among breeds. Concentrations of GH, IGF-I, insulin, and PUN were greater (P < .001) and binding activities of the 22-kDa and 20-kDa IGFBP tended (P < .10) to be greater in plasma of Brahman than in Angus or Senepol cows. Plasma glucose concentrations were greater (P < .05) in Senepol than in Brahman or Angus cows. In conclusion, Brahman (Bos indicus) and Senepol cows (tropical Bos taurus) had greater numbers of follicles in all size categories and greater diameter of CL than Angus (temperate Bos taurus) cows. These ovarian differences may be due to changes in the pattern of secretion of FSH, insulin, IGF-I, and GH but not LH, IGF-II, or IGFBP-2 or -3.

Animals↗
PubMed1999

Effect of hexachlorobenzene on NADPH-generating lipogenic enzymes and L-glycerol-3-phosphate dehydrogenase in brown adipose tissue.

The effect of the in vivo administration of hexachlorobenzene (HCB) (100 mg/100 g bw) for 30 days, on the activities of brown adipose tissue (BAT) lipogenic enzymes, i.e. malic enzyme (ME), and glucose-6-phosphate dehydrogenase (G6PD) and the mitochondrial non lipogenic enzyme, L-glycerol-3-phosphate dehydrogenase (LG3PD), was studied in male Wistar rats, submitted to various neurohormonal manipulations. BAT ME, G6PD and LG3PD activities showed significant reductions in response to HCB treatment both in euthyroid and surgically thyroidectomized rats, showing that the effect does not depend on the presence of thyroid hormones. These results differ from those obtained for hepatic ME and G6PD activities, which increased in HCB intoxicated rats without alteration in LG3PD. HCB decreased BAT ME activity under BAT denervation. Administration of HCB resulted in time and dose-dependent decreases in the activity of BAT malic enzyme. The basal activity of ME was increased in hypothyroid rats, while that of LG3PD was reduced. A stimulatory effect of receptor-saturating doses of triiodothyronine (T3) (50 microg/100 g body weight) was observed on BAT ME and LG3PD activities in thyroidectomized rats, showing that the enzymes responded to thyroid hormone stimulation in a normal manner. The stimulatory effect of saturating doses of T3 on ME and LG3PD was reduced by HCB. The results presented herein unequivocally show that brown adipose tissue is a specific target in HCB-induced toxicity, which in turn involves severe alterations in the regulation of BAT lipogenesis.

Adipose Tissue, Brown↗
PubMed1999

Crossmodal associative memory representations in rodent orbitofrontal cortex.

Firing patterns of neurons in the orbitofrontal cortex (OF) were analyzed in rats trained to perform a task that encouraged incidental associations between distinct odors and the places where their occurrence was detected. Many of the neurons fired differentially when the animals were at a particular location or sampled particular odors. Furthermore, a substantial fraction of the cells exhibited odor-specific firing patterns prior to odor presentation, when the animal arrived at a location associated with that odor. These findings suggest that neurons in the OF encode cross-modal associations between odors and locations within long-term memory.

Animals↗
PubMed1998

Cloning and sequence analysis of the Pichia pastoris TRP1, IPP1 and HIS3 genes.

The Pichia pastoris TRP1 and HIS3 genes were cloned by complementation of the Saccharomyces cerevisiae trip1 and his3 mutants, respectively, and their nucleotide sequence was determined. The P. pastoris TRP1 gene includes an open reading frame (ORF) of 714 nucleotides corresponding to a polypeptide of 237 amino acids whose sequence shares about 40% identity with that of TRP1 encoding proteins in other yeast species. DNA sequencing showed that an ORF of 858 nucleotides, encoding a protein of 285 amino acids with high homology to inorganic pyrophosphatases (IPP1), is located downstream of the P. pastoris TRP1 gene. Both genes converge in this chromosomal region, showing a genetic organization analogous to that found in the Kluyveromyces lactis genome. The P. pastoris HIS3 gene possesses an ORF of 675 nucleotides, encoding a polypeptide of 224 amino acids which shows 74.1% identity to the homologous S. cerevisiae protein. The hexameric consensus GCN4 binding sequence (TGACTC), characteristic of many amino acid biosynthetic genes, is present in the promoter region.

Aldose-Ketose Isomerases↗
PubMed1998

Modulation of tubulin polypeptide ratios by the yeast protein Pac10p.

Normal assembly and function of microtubules require maintenance of the proper levels of several proteins, including the tubulin polypeptides themselves. For example, in yeast a significant excess of beta-tubulin causes rapid microtubule disassembly and subsequent cell death. Even the modest excess of beta-tubulin produced by genetic alterations such as deletion of the minor alpha-tubulin gene TUB3 affects cell growth and can confer microtubule phenotypes. We show here that the levels of the yeast protein Pac10p affect the relative levels of the tubulin polypeptides. Cells deleted for PAC10 have the same phenotypes as do cells that express reduced levels of alpha-tubulin or Rbl2p, two proteins that bind beta-tubulin. Conversely, overexpression of Pac10p enhances the ability of alpha-tubulin or Rbl2p to suppress the lethality associated with excess beta-tubulin. However, Pac10p is itself not a beta-tubulin binding protein. Pac10 null cells show a 30% decrease in the ratio of alpha-tubulin to beta-tubulin. The results suggest that Pac10p modulates the level of alpha-tubulin in the cell, and so influences microtubule morphogenesis and tubulin metabolism.

Cloning, Molecular↗
PubMed1998

[Behavioral evaluation of the unilateral lesion model in rats using 6-hydroxydopamine. Correlation between the rotations induced by D-amphetamine, apomorphine and the manual dexterity test].

INTRODUCTION: Evaluation of rotatory activity induced by dopaminergic agonists is the most widely used test of conduct for the measurement of dopaminergic depletion of a unilateral lesion of the striatonigral pathway caused by 6-hydroxydopamine (6-OHDA) in rats, since it is quantitatively related to the extension of the dopaminergic denervation. OBJECTIVE: The objective of this study was to evaluate, from different angles, the changes in conduct seen in the model of unilateral lesion with 6-OHDA and to establish correlation with the rotation induced by D-amphetamine and by apomorphine and the ladder test. MATERIAL AND METHODS: Male Wistar rats were used. Lesions were produced in the SNpc by stereotactic injection of 6-OHDA into the right hemisphere and the effectiveness of the lesions was studied using the rotary conduct induced by D-amphetamine and apomorphine. The motor ability of the front legs was measured by the ladder test, carried out under standard and forced conditions. RESULTS: All the animals with lesions had difficulty in reaching food with both legs, although the most pronounced deficit was in the leg contralateral to the lesion. The ladder test correlated better with rotatory activity induced by apomorphine than by D-amphetamine. CONCLUSION: The animals with most dopamine loss showed most deficient use of their front legs.

Animals↗
PubMed1997

[Tuberculosis outbreak: significance of exposure time versus proximity to infection source].

BACKGROUND: The polymorphic length restriction fragment technique (PLRF) complements epidemiologic investigations. The aim of this study was to present an outbreak of tuberculosis in which the risk factors of infection and disease were studied. PATIENTS AND METHODS: A descriptive study was carried out in cases of tuberculosis. The isolated strains of Mycobacterium tuberculosis were typed by the PLRF technique. A study of the prevalence of infection was carried out among the 61 classmates of two classrooms (A and B) which the index case attended. An historical cohort study was thereafter performed among the cases with infection. The association of the dependent variable (infection or tuberculosis disease) with the remaining variables was determined by the odds ratio (OR). RESULTS: The incidence of disease was 9.8% (6/61). The strains isolated in 5 patients presented the same PLRF pattern. The prevalence study detected 28 infections (45.9%). Five cases (17.9%) were detected on the second tuberculin test. By multivariate analysis showed that the hours of exposure (1.8-3.2 hours, OR = 2.0; > 3.2 hours; OR = 10.2) were the risk factor for infection. The BCG vaccine, the intensity of the reaction to the tuberculin test and age could be associated with the risk of disease. CONCLUSIONS: The focus of the outbreak was confirmed by the PLRF technique. The importance of repeating the tuberculin test in whom the test was negative on the first test is of note. To evaluate the risk of infection the time of exposure is more important than the proximity to the index case.

Adolescent↗
PubMed1997

Regional distribution of specific high affinity binding sites for 3H-imipramine and 3H-paroxetine in human brain.

The binding of 3H-paroxetine and 3H-imipramine has been compared in 17 different regions of 12 human control brains. Our findings reveal that the regional distribution is similar for both radioligands and their bindings tend to be parallel in the brain. The highest binding site density was found in basal ganglia (hypothalamus Bmax 780 +/- 102 fmol/mg protein for 3H-imipramine binding and Bmax 515 approximately 83 for 3H-paroxetine binding). The lowest values were found in cortical areas (cingulate cortex 191 +/- 18.5 fmol/mg for 3H-imipramine binding and 88 +/- 7.5 fmol/mg for 3H-paroxetine binding). The Kd values for 3H-paroxetine binding to neuronal membranes were similar in all brain regions (mean +/- s.d. Kd 0.07 +/- 0.007 nM) and also for 3H-imipramine binding (mean +/- s.d. Kd 1.05 +/- 0.12 nM). As these values are the same as in platelet membrane, the results obtained indicate that both binding sites are identical in neuronal and in platelet membranes. These findings suggest that both ligands are good markers of the 5HT transporter. However, the higher affinity of 3H-paroxetine confirms that this compound is a better radioligand for the 5HT uptake site.

Adult↗