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Biomedical subjects

Y Pérez

Publications and source records attributed to Y Pérez.

11 recordsLinked to original sources
PubMed2006

Immobilizing Cu,Zn-superoxide dismutase in hydrogels of carboxymethylcellulose improves its stability and wound healing properties.

Hydrogels of carboxymethylcellulose (CMC) with 50 and 90% cross-linking degree (CMC50% and CMC90%, respectively) were prepared and loaded with bovine erythrocyte Cu,Zn-superoxide dismutase (SOD) to obtain two drug delivery systems: SOD-CMC50% and SOD-CMC90%. Resistance of native SOD to inactivation by H2O2 and the effect of applying SOD-CMC hydrogels to open wounds of rats' back skin were examined and compared to that of SOD trapped into CMC50% and CMC90% hydrogels. Also, the effect of CMC50% and SOD-CMC90% on human fibroblasts proliferation was evaluated at different times. It was found that SOD in the hydrogel was more resistant to H2O2 inactivation than the native enzyme and at the same time it reduced the time necessary for wound healing. Furthermore, the highest cell proliferation value was found for the CMC50% hydrogels, which had a three-dimensional structure suitable for gas and nutrient exchanges and improving cell life conditions.

Carboxymethylcellulose Sodium↗
PubMed2001

2.8-A crystal structure of a nontoxic type-II ribosome-inactivating protein, ebulin l.

Ebulin l is a type-II ribosome-inactivating protein (RIP) isolated from the leaves of Sambucus ebulus L. As with other type-II RIP, ebulin is a disulfide-linked heterodimer composed of a toxic A chain and a galactoside-specific lectin B chain. A normal level of ribosome-inactivating N-glycosidase activity, characteristic of the A chain of type-II RIP, has been demonstrated for ebulin l. However, ebulin is considered a nontoxic type-II RIP due to a reduced cytotoxicity on whole cells and animals as compared with other toxic type-II RIP like ricin. The molecular cloning, amino acid sequence, and the crystal structure of ebulin l are presented and compared with ricin. Ebulin l is shown to bind an A-chain substrate analogue, pteroic acid, in the same manner as ricin. The galactoside-binding ability of ebulin l is demonstrated crystallographically with a complex of the B chain with galactose and with lactose. The negligible cytotoxicity of ebulin l is apparently due to a reduced affinity for galactosides. An altered mode of galactoside binding in the 2gamma subdomain of the lectin B chain primarily causes the reduced affinity.

Amino Acid Sequence↗
PubMed1998

Endometrial changes according to hormone replacement therapy schedule.

OBJECTIVE: The purpose of this study was to assess differences in endometrial thickness, ultrasonographic characteristics, and histological and bleeding patterns in two groups of women according to the type and length of hormone replacement therapy (HRT) administered. DESIGN: Twenty-seven women were divided into two groups. Group I received oral conjugated estrogens 0.625 mg/day for 21 days, plus chlormadinone 2 mg the last 12 days, for a median length of 6.5 months' time. Group II received oral conjugated estrogens 0.625 mg/day plus chlormadinone 1 mg/day, both continuous and uninterrupted (n = 13), for a median length of 3 months' time. Using transvaginal ultrasound, endometrial thickness, refringence, and the presence of liquid in the uterine cavity were analyzed. An endometrial biopsy was performed the same day and the histological and bleeding patterns were described. Statistical analysis was performed with Mann-Whitney U test, Fisher's exact test, and Spearman correlation coefficient. RESULTS: Results of these tests showed that liquid in the uterine cavity and secretory endometrium were frequently found in those with sequential schedule (Group I); regular uterine bleeding was also frequent in this group. Negative correlation coefficients were found in this group between duration of HRT and endometrial thickness and uterine bleeding patterns, and in the continuous schedule group, between the duration of HRT and uterine bleeding pattern. CONCLUSIONS: We conclude that endometrial and ultrasonographic changes depend on the type of HRT schedule and the duration of therapy.

Administration, Oral↗
PubMed1997

Is left atrial appendage flow a predictor for outcome of cardioversion of nonvalvular atrial fibrillation? A transthroacic and transesophageal echocardiographic study.

Accurate echocardiographic parameters for predicting the success of cardioversion or maintenance of sinus rhythm are poorly defined. This prospective transthoracic and transesophageal echocardiographic study was conducted to test the hypothesis that the left atrial appendage flow pattern could be a predictive parameter of the success of cardioversion and maintenance of sinus rhythm in patients with nonvalvular atrial fibrillation. Eighty-two consecutive patients with nonvalvular atrial fibrillation of <6 months' duration underwent transesophageal examination after transthoracic echocardiography. After exclusion of left atrial thrombus, pharmacologic (n = 18) or electrical (n = 64) cardioversion was successful in 75 of 82 patients. In the group that underwent successful cardioversion, maintenance of sinus rhythm (n = 35) or recurrence of arrhythmia (n = 40) was assessed during a 1-year follow-up. During transesophageal examination, five left atrial appendage thrombi were found, spontaneous echo contrast was present in 26 (32%) patients, and mean peak left atrial appendage emptying velocity was 35 +/- 18 cm/sec. Peak left atrial appendage emptying velocity was found to be statistically related to parameters of left ventricular and left atrial function but not to long-term maintenance of sinus rhythm. No other echocardiographic parameter was identified as a predictor for either the success of cardioversion or the maintenance of sinus rhythm at follow-up. In patients with nonvalvular atrial fibrillation of recent onset, peak left atrial appendage emptying velocity appears to be a complex parameter depending on left atrial and left ventricular function but that does not predict either the success rate of cardioversion or long-term maintenance of sinus rhythm after successful cardioversion.

Aged↗
PubMed1997

[Echocardiographic factors predicting the maintenance of sinus rhythm one year after cardioversion for non-valvular atrial arrhythmias].

Echocardiographic factors predictive of the maintenance of sinus rhythm after successful cardioversion were investigated in 94 patients with non-valvular atrial arrhythmias of recent onset. Seventy-five patients with atrial fibrillation and 19 with atrial flutter admitted for reduction of their arrhythmias underwent transthoracic and transoesophageal echocardiography. After excluding a thrombus in the left atrial appendage or checking that it had disappeared (5 patients), and electrical (n = 74) or pharmacological (n = 20) cardioversion was successfully performed. The maintenance of sinus rhythm (n = 44) or recurrence of arrhythmia (n = 50) were controlled every 3 months for one year. The mean value of the peak positive blood flow in the left atrial appendage was 38 +/- 20 cm/s for the whole group. It was not possible to identify an echocardiographic parameter predictive of maintenance of sinus rhythm at one year either in the whole group or in the subgroups with atrial flutter or atrial fibrillation. In the group in atrial flutter, the mean value of the peak positive blood flow in the left atrial appendage was significantly greater than in the group with atrial fibrillation: 49 +/- 22 cm/s vs 35 +/- 18 cm/s, respectively; p < 0.05. The peak of positive flow in the left atrial appendage was statistically related to indirect parameters of left atrial function and of left ventricular function in the group with atrial fibrillation but only with parameters of left ventricular function in the smaller group with atrial flutter.

Aged↗
PubMed1993

Effect of age on theophylline pharmacokinetics in dogs.

Differences between neonatal and adult animals in their response to drugs can usually be attributed to altered disposition processes. Effect of age on the pharmacokinetics of theophylline was determined after IV administration of the drug to 10 groups of dogs at 1, 2, 3, 4, 8, 12, 16, 24, 52, and 104 weeks of age. Plasma theophylline concentration curves for all groups were adjusted to a biexponential kinetic, with rapid initial distribution phase and slower elimination phase. It also was noticed that young dogs have a slower elimination half-life (1 week old, t 1/2 beta = 987 minutes) than do older animals (8 weeks old, t 1/2 beta = 138 minutes). The values then plateaued until 16 weeks of age, increasing slightly at more advanced age (104 weeks old, t 1/2 beta = 282 minutes). A similar pattern was followed with respect to clearance (1-week-old pups, Cl = 1.17 ml/min/kg of body weight), which increased progressively to reach a value of 7.09 ml/min/kg at 16 weeks of age, then decreased to 3.5 ml/min/kg at 104 weeks of age. Volume of distribution beta, in relation to body weight, was not significantly different between age groups (between 1.2 and 1.6 L/kg; P < or = 0.03). Theophylline biotransformation mechanisms may be mainly responsible for Cl and t 1/2 beta variations. This leads us to suggest that quantitative and qualitative modifications in the P-450 mono-oxygenase system are responsible for the variations observed in pharmacokinetic variables of theophylline between dogs of different ages. These findings may have clinical relevance with regard to therapeutic range of theophylline.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1991

[The intelligence quotient and malnutrition. Iron deficiency and the lead concentration as confusing variables].

This study gave us the opportunity to know the roles iron deficiency and the presence of lead in blood play, as confounding variables, in relation to the state of malnutrition and the intellect of those children. A sample of 169 school children were classified according to their state of nutrition, their condition in reference to serum iron and lead concentrations. In addition, their intelligence was evaluated. The results confirmed that those children with lower weights and heights registered lesser points of intelligence; in fact, iron deficiency cancels out the difference in favor of those taller and weighing more. Lead did not contribute as a confounding variable, but more than half of the children showed possible toxic levels of this metal.

Anemia, Hypochromic↗
PubMed1990

Tuberculous meningitis. Short course of chemotherapy.

In March 1986, we began a 6-month short course trial of therapy for tuberculous meningitis, in which 28 patients were analyzed. The diagnosis was based on the following cerebrospinal fluid test results: in 53.5% of the cases, Mycobacterium tuberculosis was identified by direct smear; in 57%, culture in Löwenstein-Jensen medium was positive; in 83.3%, the detection of anti-bacille Calmette-Guérin (BCG) antibodies by enzyme-linked immunosorbent assay was positive; and in 74%, the dosification of adenosine deaminase activity was positive. In addition, in 21.4% of the cases, the diagnosis was established by means of autopsy findings. Moreover, the diagnosis was supported by bacteriological analyses from another tissue or body fluids. Despite the administration of an antituberculous therapy, 32.4% of the patients died: all of the decreased had reached the last stage of the disease by the beginning of treatment. Sixteen percent of the patients who survived after more than 18 months of follow-up after therapy had ended suffered neurological sequelae. With the 6-month therapeutic regimen, the morbidity/mortality is similar to that found in the longer-course therapies. The latter regimen is therefore thought to be a good and acceptable therapeutic option for the treatment of tuberculous meningitis.

Adolescent↗
PubMedDate not supplied

Antioxidant effects of D002 on the in vitro susceptibility of whole plasma in healthy volunteers.

BACKGROUND: It has been recently shown that oral administration of D002, a mixture of higher aliphatic primary alcohols isolated from beeswax, inhibits rat microsomal lipid peroxidation. This justified the present attempt to investigate whether D002 also exerts antioxidant effects in humans. METHODS: The effects of D002 on lipid peroxidation were studied in a double-blind, randomized, placebo-controlled trial conducted in 50 healthy volunteers. Unfractionated plasma samples at baseline and at 12 weeks were subjected to in vitro copper-induced lipid peroxidation and conjugated diene generation was monitored by changes of optical density. RESULTS: The oral treatment with D002 (50 mg/day) not only significantly prolonged (p <0.001) lag time before the onset of conjugated diene formation compared with that of baseline but also increased (p <0.05) lag phase when compared with placebo group. In fact, in the D002 group the lag-phase of oxidation was prolonged 1.5-fold. D002 oral treatment decreased TBARS and increased plasma total antioxidant status (TAS) (p <0.01). CONCLUSIONS: Because prooxidant states have been linked to normal senescence and some age-related diseases, the present data suggest that D002 may find a use in preventing age-related diseases as a dietary natural antioxidant supplement.

Administration, Oral↗