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D Balas

Publications and source records attributed to D Balas.

At least 19 recordsLinked to original sources
PubMed2003

Prevalence and mechanisms of hyperhomocysteinemia in elderly hospitalized patients.

BACKGROUND: Plasma homocysteine concentrations increase with age and remain an independent risk factor for vascular disease in the elderly. There are negative correlations between plasma homocysteine and serum folate and vitamin B12 concentrations. Two mechanisms, poor nutritional status, and chronic atrophic gastritis, could explain hyperhomocysteinemia. OBJECTIVE: The purpose of the study was to determine prevalence and mechanisms of hyperhomocysteinemia in older hospitalized patients. DESIGNS: During a 12-month period, all the consecutive hospitalized patients who underwent gastric endoscopy were recruited in this observational prospective study. Clinical, histological, and biological data concerning nutritional status, gastric analysis, homocysteine, vitamin B12, and folate concentrations were collected during the study for each included patient. RESULTS: One hundred and ninety six patients (132 women and 64 men, mean age: 85.3 5.7 years) were included. Hyperhomocysteinemia (>or= 18 mmol/l) was diagnosed in 45.4 %, cobalamin deficiency in 13.3 %, and folate deficiency in 11.7 % patients. Hyperhomocysteinemia was significantly correlated to cobalamin deficiency (r = - 0.21; p = 0.005). In a sub group of patients without hypothyroidism, or chronic renal impairment, univariate and multivariate analysis showed a significant association between hyper homocysteinemia and low MNA (OR: 0.92; 95% CI 0.85-0.99), and low albumin (OR: 0.92; 95% IC: 0.83-0.99; p = 0.04). No correlation was found between homocysteine concentrations and chronic atrophic gastritis or Helicobacter pylori infection. CONCLUSION: Hyperhomocysteinemia seems to be frequent in the elderly and is associated with poor nutritional status rather than chronic atrophic gastritis.

Aged↗
PubMed2001

Changes in cell proliferation and differentiation of adult rat small intestine epithelium after adrenalectomy: kinetic, biochemical, and morphological studies.

The effects of 10-day bilateral adrenalectomy on morphometry, proliferation, and apoptosis were determined in the small intestine of 3-month-old Sprague-Dawley rats. The activities of sucrase, lactase, and its respective mRNA, aminopeptidase N, and intestinal alkaline phosphatase were also evaluated. Adrenalectomy lead to partial atrophy and disorganization of the epithelium, with an increased number of goblet and Paneth cells and a reduction of crypt cell proliferation paralleled by a marked increase in villus apoptosis. Biochemical assays revealed that aminopeptidase N and intestinal alkaline phosphatase activities were significantly decreased, whereas disaccharidases were increased by adrenalectomy. The corresponding induction of lactase mRNA suggests an active response of the epithelium. In conclusion, adrenalectomy modified maturation and the differentiation processes of the small intestinal mucosa, especially in the proximal part of the small intestine. This result points to an important role of adrenals and glucocorticoids in the trophic status of the adult small intestinal mucosa.

Adrenalectomy↗
PubMed2000

Fluoroquinolones inhibit preferentially Streptococcus pneumoniae DNA topoisomerase IV than DNA gyrase native proteins.

The genes encoding the subunits of DNA topoisomerase IV (parC and parE) and DNA gyrase (gyrA and gyrB) of Streptococcus pneumoniae were cloned and overproduced in Escherichia coli by using the T7promoter-T7 RNA polymerase system. The four subunits were separately purified to near homogeneity by column chromatography. Protein purification was achieved by DEAE-sepharose, heparin-agarose, and hydroxylapatite chromatography. DNA topoisomerase IV was reconstituted when ParC and ParE were combined at a 3.8-fold excess of ParE. The reconstituted topoisomerase IV showed to generate efficient ATP-dependent DNA decatenation activity. The DNA gyrase ATP-dependent supercoiling activity was reconstituted by mixing equimolar amounts of the two gyrase subunits. The inhibitory effects of four representative fluoroquinolones on the DNA decatenation activity of topoisomerase IV and DNA supercoiling of gyrase have been examined and compared. All four compounds were more active in inhibiting topoisomerase IV than gyrase. Moreover, there was a positive correlation between the inhibitory activity against topoisomerase IV decatenation and DNA gyrase supercoiling. The classification of the four fluoroquinolones, considering their inhibitory activities in decatenation, supercoiling and growth was the following: clinafloxacin > trovafloxacin > sparfloxacin > ciprofloxacin. These results suggest these drugs primarily target topoisomerase IV of S. pneumoniae, and gyrase secondarily, in agreement with genetic data.

Anti-Infective Agents↗
PubMed1998

Fluoroquinolone resistance mutations in the parC, parE, and gyrA genes of clinical isolates of viridans group streptococci.

The nucleotide sequences of the quinolone resistance-determining regions (QRDRs) of the parC and gyrA genes from seven ciprofloxacin-resistant (Cpr) isolates of viridans group streptococci (two high-level Cpr Streptococcus oralis and five low-level Cpr Streptococcus mitis isolates) were determined and compared with those obtained from susceptible isolates. The nucleotide sequences of the QRDRs of the parE and gyrB genes from the five low-level Cpr S. mitis isolates and from the NCTC 12261 type strain were also analyzed. Four of these low-level Cpr isolates had changes affecting the subunits of DNA topoisomerase IV: three in Ser-79 (to Phe or Ile) of ParC and one in ParE at a position not previously described to be involved in quinolone resistance (Pro-424). One isolate did not show any mutation. The two high-level Cpr S. oralis isolates showed mutations affecting equivalent residue positions of ParC and GyrA, namely, Ser-79 to Phe and Ser-81 to Phe or Tyr, respectively. The parC mutations were able to transform Streptococcus pneumoniae to ciprofloxacin resistance, while the gyrA mutations transformed S. pneumoniae only when mutations in parC were present. These results suggest that DNA topoisomerase IV is a primary target of ciprofloxacin in viridans group streptococci, DNA gyrase being a secondary target.

Amino Acid Sequence↗
PubMed1998

Molecular characterization of the gene encoding the DNA gyrase A subunit of Streptococcus pneumoniae.

The gene encoding the DNA gyrase A subunit of Streptococcus pneumoniae was cloned and sequenced. The gyrA gene codes for a protein of 822 amino acids homologous to the gyrase A subunit of eubacteria. Translation of the gene in an Escherichia coli expression system revealed a 92-kDa polypeptide. A sequence-directed DNA curvature was identified in the promoter region of gyrA. The bend center was mapped and located between the -35 and -10 regions of the promoter. Primer extension analysis showed that gyrA transcription initiates 6 bp downstream of an extended -10 promoter. The possible implications of the bent DNA region as a regulatory element in the transcription of gyrA are discussed.

Amino Acid Sequence↗
PubMed1998

Pancreatic trypsinogen I expression during cell growth and differentiation of two human colon carcinoma cells.

Pancreatic trypsin has been found to induce tight junction or dome formation in some colon cancer cell lines (HT-29, Caco-2), and a tumor-associated trypsinogen, trypsinogen type II, has been isolated from another colon cancer cell line (COLO 205). We have tried to determine if trypsinogen is present and how its expression varies during cell culture in HT-29 Glc+/- and Caco-2 cells, which exhibit enterocytic differentiation, and in HT-29 Glc+ cells, which never differentiate. Trypsinogen mRNA presence and expression were demonstrated in these cells by mRNA hybridization, RT-PCR, cytoimmunofluorescence, Western immunoblot analysis, and gel filtration. Trypsinogen was found to be trypsinogen type I and was mainly in zymogen form in culture media. Differentiating cells exhibited variations in trypsinogen I expression, but cells that remained undifferentiated did not. In the differentiated cells, a high and transient peak in trypsinogen I expression was observed during the first steps of differentiation.

Adenocarcinoma↗
PubMed1997

[Prevalence of antimicrobial resistance in enterococci isolated from blood in Madrid (1994-1995)].

BACKGROUND: The aim of this study was to evaluate the antimicrobial resistance of enterococci isolated from blood samples in three hospitals in Madrid (Spain) from 1994 to 1995. METHODS: One hundred strains, 83 Enterococcus faecalis, 15 E. faecium, and 2 E. durans, isolated from January 1994 to April 1995 were studied. The minimum inhibitory concentrations (MIC) of 11 antimicrobians were determined by the agar dilution method. RESULTS: Four percent of the strains were resistant to ampicillin and 7% to penicillin. Ninety-two percent were sensitive to vancomycin. The percentage of strains with a high level of resistance (HLR) to some aminoglucoside was 60%. HLR was observed to gentamycin in 41%, to streptomycin in 46% and to kanamycin in 58% of the strains. Half of the isolates were resistant to the fluoroquinolones tested. HLR was significantly associated with aminoglucosides with HLR (MIC > or = 16 mg/l) to fluoroquinolones in the strains studied (p < 0.001). CONCLUSIONS: The incidence of resistance to ampicillin and vancomycin is low and very high to aminoglucosides and fluoroquinolones. There is also a very significant association between HLR to fluoroquinolones and HLR to aminoglucosides.

Bacteremia↗
PubMed1996

Antimicrobial susceptibilities of Campylobacter jejuni and Campylobacter coli to 12 beta-lactam agents and combinations with beta-lactamase inhibitors.

The in vitro activities of 12 beta-lactam agents against 100 thermophilic Campylobacter strains were tested. Beta-Lactamase production was detected in 88% of all strains tested. Clavulanic acid was the best inhibitor by susceptibility testing. The beta-lactams which displayed high levels of in vitro activity against Campylobacter isolates were imipenem, amoxicillin-clavulanic acid, and cefepime and, to a lesser degree, amoxicillin, ampicillin, and cefotaxime.

Anti-Bacterial Agents↗
PubMed1996

Immunohistological localization of regenerating protein in ocular structures.

PURPOSE: To investigate the presence of pancreatic stone protein (PSP)/reg (regenerating) protein in eyes and extraocular structures of rabbits, monkeys and man, according to species and age. METHODS: Rabbit eyes, with normal or de-epithelialized corneas, were taken from albino and pigmented animals. Monkey eyes were taken from cynomolgus monkeys, 2 years old. Stillborn and adult human eyes were obtained after autopsy. They were studied by immunohistochemistry methods, using a monoclonal antibody raised against human PSP. RESULTS: On rabbit ocular structures, the anti-PSP monoclonal antibody showed a strong reactivity at the level of basement membranes and basal poles of the cells of corneal and conjunctival epithelia and on basement membranes of skin and palpebral conjunctiva in eyelids. On de-epithelialized rabbit eyes, the remaining basement membrane was labeled while, along the re-epithelialization, the anti-PSP reactivity appeared with the migrating cells which cover the denuded cornea. On young monkeys, the whole corneal epithelium was reactive. Similar results were obtained from stillborn eyes, whereas no reactivity was detected on autopsy specimens from aged persons. CONCLUSIONS: As in other tissues and organs, the reg protein, in the eye, is found in structures known for their continuous and rapid renewal. This protein seems not to exist (or persist) in eyes from aged donors while it is strongly expressed in young donor eyes (monkey, stillborn baby) as well as in regenerating corneal epithelium. These findings enforce the hypothesis about the involvement of reg protein in cell proliferation and differentiation phenomena and its probable correlation with aging.

Aged↗
PubMed1996

Modulation of proliferation, second messenger levels, and morphotype expression of the rat intestinal epithelial cell line IEC-6 by fermented milk.

Trophic effects of milk fermented with Lactobacillus helveticus, Lactobacillus paracasei ssp. paracasei, Bifidobacterium sp., or the combination of Lactobacillus bulgaricus and Streptococcus thermophilus (yogurt) were studied on the IEC-6 intestinal epithelial cell line. Incorporation of [methyl-3H]thymidine, mitochondrial dehydrogenase activities, cyclic AMP production, and differentiation of levels of the IEC-6 strain were evaluated between the 15th and 30th passage in culture. All fermented and unfermented milks enhanced trophic responses of IEC-6 cells in a dose-dependent manner. Compared with the corresponding milks, supernatant fractions were more effective in stimulating mitochondrial dehydrogenase response. Fermented milk supernatants were also more effective than the corresponding unfermented fractions. Increases in DNA synthesis and cyclic AMP confirmed the activation observed with mitochondrial dehydrogenase. Yogurt induced the more trophic response with an increased number of the more differentiated cell morphotype. Fermentation with L. casei also demonstrated an important trophic adaptation of IEC-6 cells. Milk processing by lactic acid bacteria enhanced trophic and proliferation responses of intestinal epithelial cell line IEC-6. These results suggested that IEC-6 cells could represent an accurate and easy in vitro model for testing the trophic quality of various nutrients and for an optimization of physiological digestive functions.

Animals↗
PubMed1996

[Factors of pathogenicity, biotype, serotype and antimicrobial sensitivity of 150 clinical isolates of Yersinia enterocolitica (1992-1994)].

BACKGROUND: Yersinia enterocolitica is an important pathogen in temperate climates. The heterogeneity of the microorganisms covered by this denomination has a made grouping and identification schemes necessary. METHODS: A series of 150 different, consecutive isolates from patients with diarrheic syndrome living in an urban area with a population of approximately 500,000 inhabitants, were studied in order to evaluate their biochemical, antigenic and sensitivity characteristics. RESULTS: There was a high degree of uniformity among the strains isolated, 144 (96%) of which were identified as Yersinia enterocolitica sensu stricto, biotype 4, serotype 0:3. These strains presented, almost invariably, the same susceptibility pattern, being sensitive to amoxicillin/clavulanic acid, piperacillin, cefamandole, cefoxitin, gentamicin, amikacin, tetracycline and cotrimoxazole, and highly resistant to ampicillin, ticarcillin and cephazotin. In addition, 5 strains of Yersinia frederiksenii were isolated. The biochemical, epidemiological and sensitivity characteristics of these strains differed from those invariably found in the rest of the isolates. CONCLUSIONS: The data obtained in this study, shown a high degree of uniformity in the strains of Yersinia enterocolitica isolated in our area in recent years, with regard to both their biochemical characteristics and their sensitivity patterns. The isolations of the other biogroups may be regarded as extremely infrequent in the stool culture of patients with diarrhea treated in our hospitals.

Bacterial Typing Techniques↗
PubMed1995

[Enterococci isolated from blood (1989-1993): evolution of antibiotic susceptibility].

BACKGROUND: The incidence of enterococci infection is on the rise. Treatment is ever more difficult due to the intrinsic resistance to many antimicrobial and their ability to acquire new resistance. The aim of this study was to: a) determine the antibiotic sensitivity of 80 enterococci strains isolated from blood in 1989-1993 and, b) detect the possible changes in the resistance patterns over this period. METHODS: Eighty enterococci strains isolated from blood cultures, since 1989 to 1993 were studied. Sixty-nine were Enterococcus faecalis and 11 Enterococcus faecium. The minimum inhibitory concentrations (MIC) of 11 antimicrobial was determined by the agar dilution method. The Mantel-Haenszel and Fisher tests were used for statistical analysis of the results. RESULTS: All the strains were sensitive to ampicillin and vancomycin. A high level of resistance (HLR) to gentamycin and streptomycin was observed in 18.7% and 23.7%, respectively of the strains. Fourteen strains (17.7%) presented HLR to both antibiotics. Approximately one third of the strains were resistant to the fluoroquinolones tested. Analysis of the results by year only demonstrated a significant lineal trend of resistance for ofloxacin (p = 0.014) and a significant difference between the years for ciprofloxacin (p = 0.017). Strains with an MIC > or = 16 mg/l of fluoroquinolones presented HLR to gentamycin (p < 0.001) and to all the aminoglucosides (p < 0.001). CONCLUSIONS: The incidence of antibiotic resistance of enterococci isolated from blood in the authors hospital is generally low and, with the exception of the fluoroquinolones, did not demonstrate any significant differences during the period studied. Periodic updating and analysis of sensitivity results are required to monitor any changes which may occur over time.

Drug Resistance, Microbial↗
PubMed1994

Multicentre evaluation of the Boehringer Mannheim Hitachi 911 system for homogeneous immunoassays.

A multicentre evaluation of the new analyser, Hitachi 911, is reported for three different classes of homogeneous immunoassays (latex assays, immunoprecipitation assays, and CEDIA assays). The evaluation protocol follows ECCLS, IFCC and NCCLS guidelines. Using patient samples and commercial controls, within run and between run coefficients of variation were less than 3% in most cases, but as high as 9.7% for some CEDIA and latex assays. All the assays were linear, either in the reference or the therapeutic range of the analytes. No interference by haemolysis, lipaemia or icterus was observed. The methods were compared with other commercial methods. Coefficients of correlation were higher than 0.94 for all the methods. However, there were differences of slope and intercept for rheumatoid factor, apolipoprotein A-I and apolipoprotein B. On the Hitachi 911, all of the eight methods give precise and accurate results, and compare well with other established methods on immunoassay dedicated analysers. The discrepancies observed could be ascribed to current problems of immunoassay standardization.

Chemistry, Clinical↗
PubMed1993

[Isolated smooth muscle cells of the human colon. Cytophysiological study].

Gross normal specimens of human distal colon were obtained at operation for cancer. Smooth muscle cells were separated from internal and external layers of the muscularis. They were dissociated by digestion with collagenase, isolated and concentrated by successive centrifugations. Colonic smooth muscle cell contraction was measured using various concentrations of carbamylcholine (10(-9) to 10(-4) M); relaxation was tested using atropine (10(-9) to 10(-4) M) on colonic smooth muscle cells pre-contracted by carbamylcholine. Compared with previous descriptions, human smooth muscle cells were smaller than in other species with an enlarged distribution of cell size (30 microns to 150 microns in length). Significant dose-response curves were obtained for both carbamylcholine and atropine. However, 3 original points characterized human colonic smooth muscle cells: a) the cells isolated from the internal layer were significantly more sensitive than those isolated from the external layer (10(-9) M vs 10(-7) M); b) for the muscle cells isolated from both the internal and external layers, small colonic smooth muscle cells were significantly more sensitive. On the other hand, these cells were shown to be located near conjunctive septae, and intramural plexuses; c) analysis of contraction curves demonstrated a more efficient response for colonic smooth muscle cells of the internal layer than for those of the external layer of the muscularis.

Atropine↗
PubMed1992

[Aging of digestive tract].

Recent data on ageing of the stomach, gut and pancreatic exocrine function are discussed. Ageing seems to be responsible for several physiological changes, including hyperexcitability of gastroduodenal parietal cells, alterations in the villous surface of enterocytes resulting in decreased trophicity, and decline of pancreatic exocrine secretion. However, ageing does not appear to have major consequences in healthy elderly subjects, except for poor response to such stresses as undernutrition and illness.

Aged↗