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Biomedical subjects

I Quintana

Publications and source records attributed to I Quintana.

14 recordsLinked to original sources
PubMed2001

Unsuspected hyperhomocysteinemia in chronically anticoagulated patients.

Hyperhomocysteinemia is a risk factor for arterial and venous thrombosis. The aim of this study was to evaluate plasmatic homocysteine levels in patients under chronic anticoagulant treatment with dietary restriction of green vegetables. This kind of food is a very important source not only of vitamin K but also of folates, which are involved in Hcy metabolism. It is known that the lower the folate levels, the higher the Hcy concentration, so we suspected that these patients could show hyperhomocysteinemia. A group of patients receiving oral anticoagulant treatment and a restricted diet (Group I, n = 20) was compared with a group of untreated subjects of a similar age that were not on a restricted diet (Group II, n = 35). Group I showed significantly higher levels of plasmatic Hcy and significantly lower levels of serum folate than Group II. Therefore, a diet restricted in vitamin K applied to oral anticoagulated patients could induce an unwanted increase of homocysteine levels.

Aged↗
PubMed2001

Typing and susceptibility to penicillin of Neisseria meningitidis isolated from patients in Cuba (1993-1999).

The susceptibility to penicillin of 111 Neisseria meningitidis strains was assessed by the agar-dilution procedure and serosubtypes were determined by a whole-cell enzyme-linked immunoassay using monoclonal antibodies reagents. Thirty-five isolates showed reduced sensitivity to penicillin (MIC > or = 0.1 mg/l and < or = 1 mg/l) and no resistant strains were detected. The most common phenotype was B:4:P1.15 (77.5%) and a rising trend of non-typeable and non-subtypeable strains was detected. The increase in levels of minimal inhibitory concentrations of meningococci to penicillin gives cause for concern and the increase in non-typeable and non-subtypeable isolation demand the use of molecular biology techniques for their typing.

Antibodies, Monoclonal↗
PubMed2001

[Impact of vaccination against Haemophilus influenzae type b in Cuba].

OBJECTIVE: To assess the effectiveness of mass vaccination in Cuba of children under 2 years of age against Haemophilus influenzae type b (Hib), the most common causative pathogen of bacterial meningitis. METHODS: The availability of effective Hib conjugate vaccines led to a nationwide vaccination program in 1999 targeting all children under 2 years of age, with a 97% coverage rate achieved. To assess the program's impact, data from 1998 and 1999 from the National Bacterial Meningitis Reporting System were used. RESULTS: Vaccination efficacy was estimated at 99%. The overall incidence of Hib meningitis declined 46.1%, from 1.3 to 0.6 cases per 100,000 population. The greatest overall reduction, of 56.1%, occurred among children under 5 years of age. Among children under 1 year of age, the reduction was 70.5%, and among the rest of the age groups of children under 5, incidence decreased between 25.9% and 49.6%. In the group targeted for vaccination, incidence decreased 61.1%. Among children in the target group who contracted Hib meningitis, only 8 cases (24.2%) had been vaccinated, most with a single dose applied 1 month before becoming ill. CONCLUSIONS: Hib vaccination of all children under 2 years of age in Cuba greatly reduced the incidence of Hib meningitis, as measured by the National Bacterial Meningitis Reporting System.

Cuba↗
PubMed2000

Plasmatic homocysteine response to vitamin supplementation in elderly people.

Homocysteine (Hcy) increase is now widely accepted as a risk factor for vascular disease. The effects of folic acid (FA) and vitamins B12 and B6 in lowering Hcy have been extensively studied, but there is still little data on the response to FA dietary administration. Our purpose was to evaluate the impact of the diet and the degree of response to different doses of pharmacological FA supplementation. In a prospective, randomized, and simple blind study, 50 elderly subjects were given a 400-microg/day FA diet and were randomly assigned to one of the following treatments: Group I = placebo tablet; Group II = tablet containing 1-mg folic acid, 1-mg B12, and 25-mg B6; and Group III = tablet containing 2.5-mg folic acid and same B6 and B12 doses as Group II. Forty-four subjects completed the study, and their plasmas were evaluated. Hcy concentration significantly decreased even in patients with normal basal values, and there were no differences in the response between individuals receiving diet plus placebo and those receiving diet plus pharmacological supplementation. After the treatment, the mean decrease of plasmatic Hcy levels was 10.8 (9.4, 12.5) micromol/l, geometric mean [95% confidence interval (95% CI)], and particularly, the values for Group I were 10.6 (7.4, 14.8) micromol/l. In 31% of the subjects, the post-treatment Hcy levels were less than or = 5 micromol/l. These results show that a special diet, with or without pharmacological FA and B12 and B6 supplementation, significantly decreases the Hcy levels in elderly people. Therefore, a diet with high contents of FA might have an enormous impact on the morbidity and mortality of atherothrombosis.

Aged↗
PubMed2000

Validation of an enzyme immunoassay for the determination of total homocysteine in plasma.

In recent years, the determination of homocysteine (Hcy) has become increasingly important, since high levels of Hcy in plasma or serum represent an independent risk factor for occlusive vascular diseases. Nowadays, clinical laboratories use several analytical techniques to measure Hcy, of which high-performance liquid chromatography (HPLC) is the most popular. Recently, assays for Hcy quantification based on enzyme immunoassays (EIA) have become commercially available. Our group carried out the validation of the Axis method and compared results with those obtained by an established HPLC assay. Intra- and inter-assay coefficients of variation were < or = 8.5%. Compared with HPLC, linear regression analysis showed r=0.984, slope=0.952, intercept = 1.24 /mol/l; Bland-Altman procedure, the mean of the difference EIA-HPLC results = 0.5 micromol/l. Our results suggest that Hcy determinations by both methods are equivalent, and that the Axis assay provides reproducible and reliable data.

Homocysteine↗
PubMed1997

Plasminogen: an important hemostatic parameter in septic patients.

BACKGROUND: Previously we observed in some but not all septic patients a low plasma concentration of plasminogen. OBJECTIVES: To investigate prospectively whether plasma levels of plasminogen or the ratio of plasminogen to alpha-2-antiplasmin have a prognostic value for survival from sepsis and to study the variation of other hemostatic parameters during septicemia. PATIENTS: The study population consisted of 45 consecutive patients with septicemia, 15 non-septic patients from the same intensive care unit and 30 healthy volunteers. MEASUREMENTS AND MAIN RESULTS: Plasminogen concentrations were significantly lower (p < 0.001) in plasma of septic patients (median 0,62 IU/ml range: 0.15-1,06) than in plasma of healthy controls (median 1.00 IU/ml, range: 0.75-1.10) or of non-septic intensive care patients (median 1.00 IU/ml, range: 0.82-1.08). Among the other parameters tested, plasminogen activator inhibitor (PAI-1) antigen concentration and PAI activity were similar in septic and non-septic intensive care patients, but higher than in healthy controls. Concentrations of elastase-alpha-1-protease inhibitor or of thrombin-antithrombin complexes were higher in septic patients than in non-septic intensive care patients or healthy controls. A degraded form of plasminogen of 38 kDa was detected by Western blot analysis in the plasma of septic patients, but not in plasma of non-septic intensive care patients or controls. Plasminogen alone or the ratio of plasminogen to antiplasmin were good markers for survival from septicemia. E.g. for plasminogen at a cut off of 0.65 IU/ml, sensitivity was 90.5% and specificity 66.7%, whereas for the ratio of plasminogen over antiplasmin at a cut off ratio of 0,65 IU/ml, sensitivity was 95.2% and specificity 70.8%. CONCLUSION: Plasminogen or the ratio of plasminogen to antiplasmin are sensitive markers for survival in patients with septicemia.

Adult↗
PubMed1995

The early stimulation of glycolysis by epidermal growth factor in isolated rat hepatocytes is secondary to the glycogenolytic effect.

We have studied the relationship between the effect of epidermal growth factor (EGF) on glycogen metabolism and its effect on glycolysis, in rat hepatocyte suspensions. Although 10 nM glucagon or 10 microM adrenaline increased glycogen degradation by more than 120%, 10 nM EGF increased glycogenolysis by less than 20% in hepatocytes incubated in glucose-free medium. Both glucagon and adrenaline increased phosphorylase a activity by more than 130%; EGF increased this activity by about 30%. Under basal conditions, 65% of the glucosyl residues were released as free glucose and about 30% ended up as C3 molecules (lactate and pyruvate). Both glucagon and adrenaline decreased the proportion of glucosyl units that rendered glycolysis end-products (to 2% for glucagon and 6% for adrenaline) and increased the proportion that ended up as free glucose (to 94% and 88% of the glucosyl residues for glucagon and adrenaline respectively). EGF increased the production of both free glucose and lactate+pyruvate, but the proportion of glucosyl residues that ended up as free glucose or glycolysis end-products was unchanged. In glycogen-depleted hepatocytes incubated in the presence of 25 mM glucose, EGF affected neither glycogen deposition nor glycolysis. EGF increased cytosolic free Ca2+, and neomycin decreased both the Ca2+ signal and the glycogenolytic effect. In conclusion, our results indicate that the effect of EGF on glycolysis is secondary to the Ca(2+)-mediated stimulation of glycogenolysis in rat hepatocyte suspensions.

Animals↗
PubMed1994

Heparin cofactor II in diabetic patients.

Levels of heparin cofactor II (HCII) activity and antigen and electrophoretic pattern were studied both in normal subjects and in type I diabetic patients with high and normal levels of glycosylated haemoglobin. There was a significant reduction in HCII activity (83 +/- 7%) in patients with high levels of glycosylated haemoglobin compared with controls (95 +/- 17%; P < 0.001). However, plasma HCII antigen levels were not decreased in these patients.

Adult↗
PubMed1993

Epidermal growth factor interferes with the effect of adrenaline on glucose production and on hepatic lipase secretion in rat hepatocytes.

We studied the interaction of epidermal growth factor (EGF) and adrenaline in the control of several metabolic functions in isolated hepatocytes from fed rats. EGF did not modulate glucose release, urea production or hepatic lipase secretion, but interfered with the stimulatory effect of adrenaline on both glucose and urea production and also with the inhibitory effect of this hormone on hepatic lipase secretion. EGF also interfered with the effect of both angiotensin II and vasopressin on glucose release and on hepatic lipase secretion. While the effect of EGF interfering with the action of adrenaline on glucose release was potentiated in the absence of extracellular calcium, the effect on the inhibition of hepatic lipase secretion was abolished. These results suggest that EGF interfered with catecholamine actions in the liver at a site distal from the generation of the calcium signal.

Animals↗
PubMed1988

Carrier-mediated uptake of L-(+)-lactate in plasma membrane vesicles from rat liver.

Plasma membrane vesicles from rat liver transported L-lactate into the inner vesicular space. Kinetic analysis of L-lactate uptake gave a Km value of approx. 2.9 mM. Selective inhibition was found in a similar pattern to that described for the hepatic lactate carrier. L-Lactate transport was enhanced when a pH gradient was created across the plasma membrane. Vesicles obtained from fasted rats showed a higher uptake of L-lactate than those from fed rats, when incubated with physiological concentrations of L-lactate.

Alanine↗
PubMedDate not supplied

First epidemic of echovirus 16 meningitis in Cuba.

From April to September 2000, an epidemic of aseptic meningitis spread throughout Cuba, with 16,943 reported cases. Virologic studies identified echovirus 16 as the cause of this epidemic. This is the first reported isolate of echovirus 16 from patients with viral meningitis in Cuba.

Adolescent↗