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Biomedical subjects

M García

Publications and source records attributed to M García.

At least 109 records · Page 6Linked to original sources
PubMed2000

Thermodynamics of Association of Structurally Related Amphiphilic Penicillins.

Critical micelle concentrations (CMCs) of the penicillins cloxacillin and dicloxacillin in water were determined by conductivity measurements over the temperature range 288.15 to 313.15 K. Both penicillins showed minimum CMCs at temperatures close to 298.15 K. Thermodynamic parameters of aggregate formation were derived from the variation of the CMC with temperature using a modified form of the mass action model applicable to systems of low aggregation number. Values for the enthalpy of aggregate formation, DeltaH(0)(m), calculated by this method showed that the aggregation of both cloxacillin and dicloxacillin became increasingly exothermic with increase in temperature. The predicted DeltaH(0)(m) at 298.15 K was in good agreement with the value determined experimentally by calorimetry for each drug. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Lung cancer risk in iron and steel foundry workers: a nested case control study in Asturias, Spain.

BACKGROUND: Workers of iron and steel foundries have a high lung cancer risk but the findings on specific processes associated with this risk are inconsistent. We examined the risk of lung cancer among workers in the main industrial processes of a large iron and steel foundry in Asturias, Spain. METHODS: We conducted a nested case-control study comprised of 144 male lung cancer cases and 558 controls, selected from a study base of about 24,400 workers employed in the industry between 1952 and 1995. Cases were identified through linkage of industry records with those of two cancer registries. Controls were selected through industry records using incidence density sampling, were matched to cases by age and date of birth and had to be alive and without lung cancer at the time of selection. Smoking history was obtained through company medical records. Unconditional logistic regression was applied and all ORs were adjusted for age and tobacco consumption. RESULTS: Workers were, on an average, heavy smokers and a very strong relation was observed for smoking (OR for "ever smoker" = 32.4). Workers having ever been employed in the blast furnace had an excess lung cancer risk (OR = 2.55, 95% CI 1.25-5.21) compared to a reference group of workers not employed in metal producing departments. A similar excess was observed for workers having as their longest held job employment in the blast furnace. A two-fold risk was also observed for workers in the main foundry. For subgroups of workers, tobacco smoking appeared to be an important positive or negative confounder. CONCLUSIONS: In this large Spanish foundry, a high risk was observed for workers employed in departments with high exposure to crystalline silica, PAHs, and various other carcinogenic chemicals. Although comparisons were made between workers of the same industry, smoking habits differed and adjustment by smoking modified considerably the risk estimates.

Adult↗
PubMed2000

Effect of chain length of HAV-VP3 synthetic peptides on its interaction with biomembrane models.

Shorter analogues of a continuous epitope of hepatitis A virus, VP3(110-121) peptide, failed to react with convalescent sera, indicating the importance of the entire peptide in the epitope structure. To better understand the influence of the structural properties of this 12-mer peptide epitope on its biological activity, the interaction of smaller peptide analogues with phospholipid biomembrane models was investigated by a combination of spectroscopic and biophysical techniques. In this article we describe our findings concerning the surface activity and the interaction of peptides with simple mono- and bilayer membranes composed of a zwitterionic phospholipid (dipalmitoyl phosphatidylcholine, DPPC), an anionic phospholipid (dipalmitoyl phosphatidylglicerol, DPPG), or a DPPC/DPPG mixture. The results indicate that the net negative charge of the peptide is in some way responsible of the specific interactions between VP3(110-121) and membrane phospholipids, and necessary to induce beta-type conformations upon vesicle interaction.

Capsid↗
PubMed2000

Cerebrolysin reduces microglial activation in vivo and in vitro: a potential mechanism of neuroprotection.

Neurotrophins, such as NGF, BDNF and NT-3 play a regulatory role on the function of microglial cells in vivo and in vitro, and the identification of new compounds with neurotrophic properties is becoming a new strategy for the prevention and/or treatment of neurodegenerative disorders. In this study we describe the use of two different models to demonstrate the ability of Cerebrolysin to reduce microglial activation. The results of these in vitro and in vivo studies indicate that Cerebrolysin might exert a neuroimmunotrophic activity reducing the extent of inflammation and accelerated neuronal death under pathological conditions such as those observed in neurodegenerative diseases.

Amino Acids↗
PubMed2000

Effects of IGF-I treatment on osteopenia in rats with advanced liver cirrhosis.

IGF-I is an anabolic hormone which has been reported to increase bone formation in several conditions of undernutrition. Advanced liver cirrhosis is associated with osteopenia and also with low serum levels of IGF-I. Previous results showed that low doses of IGF-I increase osteoblastic activity and decrease bone reabsorption in early liver cirrhosis. The aim of this study was to evaluate whether IGF-I-treatment also induces beneficial effect on osteopenia associated with advanced cirrhosis. Rats with ascitic cirrhosis were divided into two groups: group CI (n=10) which received saline and group CI+IGF (n=10) which were treated with IGF-I (2 microg/100 g bw x day, sc, during 21 days). Healthy controls which received saline were studied in parallel (CO n=10). On the 22nd day, the animals were sacrificed, and bone parameters were analyzed in femur. Posterior-anterior diameter was similar in all groups. No significant differences were observed in bone content of calcium, total proteins, collagen and hydroxyapatite in cirrhotic rats as compared with controls. However, CI rats showed significant reductions in total bone density (-13.5%, p<0.001) assessed by densitometry and radiological study. In CI+IGF rat bone density (assessed by densitometry) improved significantly as compared with CI animals. In summary, osteopenia characterized by loss of bone mass and preserved bone composition was found in rats with advanced cirrhosis induced by CCl4 and phenobarbital in drinking water. This bone disorder is partially restored by treatment with low doses of IGF-I during only three weeks. Thus, IGF-I could be considered as a possible therapy for osteopenia associated with advanced liver cirrhosis.

Animals↗
PubMed2000

Parasitological indicators of onchocerciasis relevant to ivermectin control programmes in the Amazonian focus of Southern Venezuela.

In the previous paper it was concluded that those aged > or = 15 years of both sexes could comprise the indicator group for rapid epidemiological assessment (REA) of onchocerciasis in the Amazonian focus. This paper explores relationships between community microfilarial (mf) prevalence, intensity, and nodule prevalence in 20 Yanomami communities, that would allow identification of REA methods in the region. The mean nodule ratio (prevalence of nodules/prevalence of mf) was 0.54 when onchocercomata in the indicator group were considered. The Spearman correlation coefficient between mf and nodule prevalence was 0.686 (P = 0.001). Palpation of nodules had 92 % specificity and 32 % sensitivity when compared to skin-snipping for the diagnosis of onchocerciasis. The predictive value positive increased from 75 % to 81 % when the indicator group was used. A microfilarial prevalence > 75 % in this group would be indicative of hyperendemic status in the village, between 30 and 75 % of mesoendemicity, and < 30 % of hypoendemicity. For the assessment of infection intensity, biopsies may be taken from the iliac crest for all endemicity levels. Five of the hyperendemic villages surveyed in this work had a community microfilarial load (CMFL) greater than 10 mf/skin snip; the remaining 5 had a CMFL between 5 and 9. These levels of infection merit high priority ivermectin treatment. In Latin America, communities at both moderate and severe risk are included in mass chemotherapy programmes (i.e. when mf prevalence is over 20 %). Roughly, a nodule prevalence in the indicator group > 10 % would suggest a community mf prevalence > 20 % with a sensitivity of 85 % and a specificity of 71 %. A multiple linear regression model of the arc-sine transformed mf prevalence in the village (all ages) on nodule prevalence in those aged > or = 15 years and altitude of the village explained 72 % of the variance. The model combining nodule and altitudinal information had a sensitivity of 92 % and a specificity of 71 % in comparison to an estimated mf prevalence of 21 % or more. It is suggested that the usefulness of the REA methods proposed be assessed in other areas of the Amazonian onchocerciasis focus.

Adolescent↗
PubMed2000

Amazonian onchocerciasis: parasitological profiles by host-age, sex, and endemicity in southern Venezuela.

This paper describes, for the human onchocerciasis focus of southern Venezuela, the age profiles of Onchocerca volvulus microfilarial (mf) and nodule prevalence, mf intensity, and mf aggregation for the whole examined population (836 Yanomami people) living in 20 villages, and for these communities classified according to endemicity levels (hypoendemic: < or = 20 %; mesoendemic: 21-59 %; hyperendemic: < or = 60 % infected). Mf prevalence and intensity increased with age, particularly in the hyperendemic areas, and there were no marked differences between the sexes. The prevalence of nodules followed the same age pattern. Fifty percent mf prevalence was reached in the 15-19 year age-class when the population was taken as a whole; nearly in the 10 to 14-year-olds for the hyperendemic level, in those aged 20-29 years in mesoendemic areas, and not reached at all in hypoendemic villages. The degree of mf aggregation was measured by the k value of the negative binomial distribution and by the variance to mean ratio (VMR). The relationship between the standard deviation (S.D.) of mf counts and the mean mf density was also explored. These 3 indices (k, VMR, and S.D.) showed a tendency to increase with both mean mf load and host age. Since infection intensity and host age were themselves positively related, it was not possible to draw definite conclusions about age-specific changes of parasite aggregation. There was not a significant decrease of mf intensity after an earlier peak neither was there a shift towards younger ages of the maximum no. of mf/mg reached as the endemicity level increased. These results are discussed in relation to detection of density dependence in the human host, selection of an indicator age-group for rapid epidemiological assessment (REA) methods, and strategies of ivermectin distribution in the Amazonian focus. It is recommended that, for the Amazonian onchocerciasis focus, the indicator group for REA consists of all those aged 15 years and over.

Adolescent↗
PubMed2000

Usefulness of currently available methods for the diagnosis of Anisakis simplex allergy.

BACKGROUND: Serodiagnosis of anisakiosis and Anisakis allergy is difficult since many Anisakis antigens show cross-reactivity complications. In the present study, we assess the usefulness of the major immunologic methods currently available for the diagnosis of Anisakis allergy. METHODS: Four tests (skin prick test, CAP-FEIA system, Western blotting, and an antigen-capture ELISA using O-deglycosylated antigen bound by the monoclonal antibody UA3) were applied to Anisakis-free subjects and subjects with confirmed Anisakis allergy. RESULTS: The skin prick test, CAP-FEIA, and the antigen-capture ELISA identified Anisakis allergy sera with 100% sensitivity, while Western blotting showed 96%/ sensitivity. The antigen-capture ELISA also showed 100% specificity, but CAP-FEIA showed a specificity of only 50%. In Western blotting, none of the bands detected were specific for either Anisakis-free or Anisakis allergy subjects. The skin prick test was not applied to the Anisakis-free subjects, so its specificity could not be determined. CONCLUSIONS: On the basis of these results, we suggest that the most appropriate procedure for diagnosis of Anisakis allergy suspected on clinical grounds is the antigen-capture ELISA using UA3, or, alternatively, a preliminary skin prick test with a positive result subsequently confirmed by UA3-ELISA.

Adolescent↗
PubMed2000

Vaccination against hepatitis B virus in cirrhotic patients on liver transplant waiting list.

Patients with cirrhosis may fail to respond to anti-hepatitis B vaccine. An adequate response would be especially interesting when patients are on a liver transplant waiting list. Posttransplantation de novo hepatitis B has been well documented. One possible source is the grafting of organs from hepatitis B surface antigen (HBsAg)-negative, antibody to HBsAg (anti-HBs)-positive, antibody to hepatitis B core antigen-positive donors. The achievement of high titers of anti-HBs could be protective in this setting. We studied prospectively the response rate to recombinant hepatitis B vaccine (3 40-microg doses administered at 0, 1, and 2 months) in 62 patients with end-stage liver disease awaiting liver transplantation. Twenty-two patients showed antibody response (44%). A further 3 doses were administered in 15 of 28 nonresponders and were effective in 9 patients. Thus, the response rate reached 62% (31 of 50 patients completing 1 or 2 vaccination schedules before liver transplantation). Classic hepatitis B vaccination studies of patients with cirrhosis yield lower response rates. Vaccination with this double-dose schedule should be considered in such patients before liver transplantation.

Adolescent↗
PubMed2000

Molecular characterization of the Mycoplasma gallisepticum pvpA gene which encodes a putative variable cytadhesin protein.

A putative cytadhesin-related protein (PvpA) undergoing variation in its expression was identified in the avian pathogen Mycoplasma gallisepticum. The pvpA gene was cloned, expressed in Escherichia coli, and sequenced. It exhibits 54 and 52% homology with the P30 and P32 cytadhesin proteins of the human pathogens Mycoplasma pneumoniae and Mycoplasma genitalium, respectively. In addition, 50% homology was found with the MGC2 cytadhesin of M. gallisepticum and 49% homology was found with a stretch of 205 amino acids of the cytadherence accessory protein HMW3 of M. pneumoniae. The PvpA molecule possesses a proline-rich carboxy-terminal region (28%) containing two identical directly repeated sequences of 52 amino acids and a tetrapeptide motif (Pro-Arg-Pro-X) which is repeated 14 times. Genetic analysis of several clonal isolates representing different expression states of the PvpA product ruled out chromosomal rearrangement as the mechanism for PvpA phase variation. The molecular basis of PvpA variation was revealed in a short tract of repeated GAA codons, encoding five successive glutamate resides, located in the N-terminal region and subject to frequent mutation generating an in-frame UAA stop codon. Size variation of the PvpA protein was observed among M. gallisepticum strains, ranging from 48 to 55 kDa and caused by several types of deletions occurring at the PvpA C-terminal end and within the two directly repeated sequences. By immunoelectron microscopy, the PvpA protein was localized on the mycoplasma cell surface, in particular on the terminal tip structure. Collectively, these findings suggest that PvpA is a newly identified variable surface cytadhesin protein of M. gallisepticum.

Adhesins, Bacterial↗
PubMed2000

Erythrocytapheresis with recombinant human erythropoietin in hereditary hemochromatosis therapy: a new alternative.

BACKGROUND AND OBJECTIVES: The purposes of this study were to evaluate the tolerance, efficacy and safety of isovolemic erythrocytapheresis (EA) in nonanemic patients with hereditary hemochromatosis (HH), and to assess the usefulness of recombinant human erythropoietin (rHuEPO) associated with EA to reduce treatment duration. MATERIALS AND METHODS: In 10 asymptomatic patients with serum ferritin >400 microg/l, transferrin saturation >50%, and GPT elevation, EA with rHuEPO and folic acid was performed. RESULTS: Red cell indices, serum ferritin, and other iron metabolism parameters (serum iron, transferrin, and transferrin saturation); GPT and other laboratory data were considerably improved. CONCLUSION: This method offers better results in less time than traditional phlebotomy. EA with rHuEPO is an effective therapeutic alternative for patients with HH.

Adult↗
PubMed2000

Longitudinal assessment of L-T4 therapy for congenital hypothyroidism: differences between athyreosis vs ectopia and delayed vs normal bone age.

To study the effects of LT4 dose on thyroid hormone serum levels, a prospective, longitudinal and comparative study was designed, including 56 term eutrophic 1-89 day-old infants with congenital hypothyroidism (CH) detected by neonatal screening. Patients were divided into four groups according to delayed or normal bone age at birth, and athyreosis or ectopic thyroid. All received an initial dose of 50 micrograms/day (12.9-13.7 micrograms/kg/day) LT4 and were followed bimonthly (first year) and quarterly (second year) with thyroid profile and bone age determinations at 6, 12 and 24 months. At diagnosis, hormone levels were higher in cases of ectopia than in athyreosis (p < 0.001), and T4 was lower in children with delayed than in normal bone age at birth (p < 0.05). During treatment, all groups were clinically euthyroid despite T4 and FT4 serum levels higher than the upper normal limit (p < 0.0.001), though T3 and FT3 were within the normal limit (p > 0.05). TSH normalized within 8 weeks. Bone age accelerated at 2 years in eight children of the bone age delayed group. No patient had craniosynostosis.

Age Determination by Skeleton↗
PubMed2000

[The clinicopathological characteristics and prognosis of tumors of the gastrointestinal stroma].

Gastrointestinal stromal tumors form a small percentage of digestive tract tumors. They have recently been the subject of a new histopathologic classification made possible by immunohistochemical techniques. A series of criteria has been proposed which enables the identification of the most malignant and clinically aggressive tumors. We present five patients who were diagnosed with gastrointestinal stromal tumor, each of which had distinct characteristics. The different diagnostic tests performed, the difficulties of reaching a diagnosis as well as the treatment and distinct behavior of these tumors are discussed.

Adult↗
PubMed2000

[Epidemiology of non-typhoid salmonellosis in a hospital in Pontevedra (1994-1997)].

BACKGROUND: Since data on non-typhoidal salmonellosis in our health care area are scarce, we undertook an epidemiological study covering a four year period (1994-1997). METHODS: Retrospective descriptive study carried out through review of the medical and clinical microbiologic records at Hospital Provincial de Pontevedra. Culture, isolation, identification, antibiotic susceptibility and serotypification were done according to usual Clinical Microbiology protocols. RESULTS: Along the period under study 459 cases of non-typhoidal salmonellosis were diagnosed. The relative incidence was higher among pediatric than adult patients. Between 1994-1996 top incidence was detected in August, while in 1997 another maximum was found in April, closely related to climatic variations. The most frequent serogroup was D, with an increase in serogroup B since 1996. We found 16 different serotypes, being the more frequent in decreasing order Enteritidis (87.2%), Typhimurium (3.6%) and Hadar (2.3%). This distribution shows differences with regard to other national series covering a similar period of time. The more frequently detected antibiotic resistance was to ampicillin (39.0% strains), ampicillin-sulbactam (17.6%) and nalidixic acid (5.9%). Neither 3rd-generation cephalosporines nor fluoroquinolones resistance was detected. Serotype Typhimurium was the most resistant. We found association between certain resistance patterns and serotypes Hadar, Paratyphi B and Typhimurium. Most diagnosed cases corresponded to acute gastroenteritis (95.6%). Patients under 3 and over 69 suffered more frequently from extraintestinal salmonellosis. CONCLUSIONS: The high incidence of alimentary toxinfection due to Salmonella spp. in our area should warrant strict epidemiological surveillance programmes to detect sources of infection, evaluate sanitary control measures and use of antibiotics.

Adult↗
PubMed2000

[Biliary acute pancreatitis: an etiopathology and evolution review of 148 cases].

BACKGROUND: A retrospective analysis of the etiologic factors and physiopathogenic mechanisms underlying an acute biliary pancreatitis episode put in evidence the complexity of the attempt to acquire a clear understanding of the entity. In this presentation the authors try to re-examine the main factors involved in the triggering of the disease. Besides the classic theories and their own approach to the management of an acute pancreatic inflammation episode are discussed. AIMS: The main purpose of this endeavor was to identify and discuss the etiopathogenic mechanisms that were prevalent in a series of 148 patients observed and treated in a 10 years period. Besides, another distinctive aim was to analyze their evolution and somehow to try to assess their probable prognosis. PLACE OF APPLICATION: Close community. POPULATION: The whole group of patients that were admitted with the diagnosis of acute pancreatitis in the time period comprised between 1987-1997. METHODS: The acute pancreatitis subgroups and their respective number of patient included were the following: BILIARY ACUTE PANCREATITIS 140 CASES POST ERCP 8 CASES CONCLUSIONS: As a result of the present reviewing endeavour several observations deserve to be pointed out: a. The pancreatic gland undoubtedly is a neuroendocrine organ, that is subjected to complex neural and hormonal influence. b. Undeniably, the involvement of the autonomic nervous system in the physiopathogenic mechanism of acute pancreatitis has been surprisingly disregarded. c. The biliary acute pancreatitis variant is the most frequent. What we consider a simplification is to accept the Opie's postulation without taking into account the intermediate steps, centered on autonomic reflexes, that ultimately lead to the acute inflammatory lesions. d. Although without an absolute proof, it is undeniable that "stress" is a primary etiology in some cases of acute pancreatitis. e. We favor the idea that the pancreas functional status influences on the extension and intensity degree of the acute pancreatic inflammatory lesions.

Acute Disease↗
PubMed2000

[Isolated primary hyperaldosteronism caused by adrenocortical carcinoma].

OBJECTIVE: To report a case of adrenocortical carcinoma and primary aldosteronism as the sole endocrine manifestation. METHODS/RESULTS: A 39-year-old male with adrenocortical carcinoma and primary aldosteronism is presented. Following complete hormonal and radiological evaluation, right adrenalectomy and nephrectomy were performed (pT2pN0M0, stage II). Blood pressure, serum potassium and aldosterone levels returned to normal. The patient received adjuvant therapy with carboplatin and etoposide. After 15 months' disease-free interval, lung metastasis was diagnosed, without evidence of local recurrence until 5 months later, when hypertension and primary hyperaldosteronism reappeared. There were no other endocrine disorders. Treatment with spironolactone, 5-FU and adriamycin was instituted with no tumor response and the patient died 3 years later from complications of endobronchial metastasis. CONCLUSION: Adrenocortical carcinoma with isolated primary hyperaldosteronism is uncommon and consequently there is no wide experience in regard to its diagnosis and treatment. Although randomized studies are not available, adjuvant therapy using other agents instead of mitotane (o,p-DDD), such as the combination of cisplatin and etoposide (VP-16), seems reasonable in the locally advanced stages. Mitotane may be useful when hypercortisolism is present, but its efficacy as an antitumor agent has been controversial.

Adrenal Cortex Neoplasms↗