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Biomedical subjects

J A Orozco

Publications and source records attributed to J A Orozco.

8 recordsLinked to original sources
PubMed2001

Polyphenol oxidase activity, color changes, and dehydration in table grape rachis during development and storage as affected by n-(2-chloro-4-pyridyl)-n-phenylurea.

Flame Seedless grapes were sprayed with N-(2-chloro-4-pyridyl)-N-phenylurea (CPPU) at 0, 2.5, and 5.0 ppm to develop rachis resistant to browning and dehydration. Rachis polyphenol oxidase (PPO) activity was determined during cluster development. Cluster components were weighed at commercial (CM), and physiological maturity (PM). PPO activity, rachis color changes (L and a), and cluster weight loss were evaluated at 0 degrees C for 8, 16, 32, and 56 days. CPPU-treated rachis had a decrease of 36% in PPO activity and a week delay in peak activity. At PM, dry weight of CPPU-treated rachis increased by 3 g. Postharvest rachis PPO activity declined with CPPU application, and color changes followed the same pattern for CM and PM. After 32 days of storage, L and a in lateral branches were significantly superior in CPPU treatments. Weight losses below 2.1% were significantly lowest in CPPU-treated clusters for 16 days of storage regardless of cluster maturity.

Catechol Oxidase↗
PubMed2000

Leukocyte accumulation and hemodynamic changes in the cerebral microcirculation during early reperfusion after stroke.

BACKGROUND AND PURPOSE: Leukocytes contribute to cerebral ischemia-reperfusion injury. However, few experimental models examine both in vivo behavior of leukocytes and microvascular rheology after stroke. The purpose of the present study was to characterize patterns of leukocyte accumulation in the cerebral microcirculation and to examine the relationship between leukocyte accumulation and microcirculatory hemodynamics after middle cerebral artery occlusion and reperfusion (MCAO-R). METHODS: Male rats (250 to 350 g) were anesthetized and ventilated. Tail catheters were inserted for measurement of arterial blood gases and administration of drugs. Body temperature was maintained at 37 degrees C. Animals were subjected to 2 hours of MCAO by the filament method. A cranial-window preparation was performed, and the brain was superfused with warm, aerated artificial cerebrospinal fluid. Reperfusion was initiated by withdrawing the filament, and the pial microcirculation was observed by use of intravital fluorescence microscopy. Leukocyte accumulation in venules, arterioles, and capillaries; leukocyte rolling in venules; and leukocyte venular shear rate were assessed during 1 hour of reperfusion. RESULTS: We found significant leukocyte adhesion in cerebral venules during 1 hour of reperfusion after 2 hours of MCAO. Leukocyte trapping in capillaries and adhesion to arterioles after MCAO-R tended to increase compared with controls, but the increase was not significant. We also found that shear rate was significantly reduced in venules during early reperfusion after MCAO. CONCLUSIONS: A model using the filament method of stroke and fluorescence microscopy was used to examine white-cell behavior and hemodynamics in the cerebral microcirculation after MCAO-R. We observed a significant increase in leukocyte rolling and adhesion in venules and a significant decrease in blood shear rate in the microcirculation of the brain during early reperfusion. Leukocytes may activate and damage the blood vessels and surrounding brain cells, which contributes to an exaggerated inflammatory component to reperfusion. The model described can be used to examine precisely blood cell-endothelium interactions and hemodynamic changes in the microcirculation during postischemic reperfusion. Information from these and similar experiments may contribute to our understanding of the early inflammatory response in the brain during reperfusion after stroke.

Animals↗
PubMed1998

Risk factors for osteoporotic hip fractures in Mexicans.

BACKGROUND: Osteoporosis (OP) and its fractures are a major problem due to their impact in morbidity and mortality in the elderly. Although this entity is well studied in other countries, OP and its fractures have not been evaluated carefully in our population. The objective was to assess risk factors for osteoporotic hip fracture in Mexicans. METHODS: A total of 295 subjects, 152 cases and 143 controls, were studied. Cases were patients with hip fracture, of both sexes and 45 years of age or older. Controls were healthy subjects who were in hospital waiting rooms accompanying patients without hip fractures. A questionnaire covering known possible risk factors for osteoporotic hip fracture was administered by the same evaluator to all subjects. Pelvic roentgenograms, anterior-posterior view, were obtained in both cases and controls to perform the Singh index and the cortical index of the femur. RESULTS: Fractures were present in (72.2%) of women. Weight and any alcohol ingestion were associated with an increased risk of hip fracture. The odds ratio (OR) for low weight by the Quetelet Index was 4.03 (95% CI 1.93-8.39) p < 0.001. Any alcohol intake was associated with an OR of 1.73 (95% CI 1.04-2.90) p < or = 0.03 for the total group, and 2.78 (95% CI 1.25-6.14) p < or = 0.003 for women. Controls had a significantly higher mean daily calcium intake compared to cases (mean, SD 575.9 +/- 297.2 vs. 490.4 +/- 245.5, p < or = (0.007). Family history, smoking, physical activity, pregnancies, breastfeeding or concomitant diseases were not associated with risk of hip fracture. CONCLUSIONS: This study confirmed the risk factors for osteoporotic hip fracture in Mexicans, previously shown for other ethnic groups. Further research in different factors, such as rate of bone turnover, anthropometric dimensions, and genetic studies (osteoporosis gene) are needed in order to define the differences among ethnic groups.

Aged↗
PubMed1995

Continuous regional cerebral cortical blood flow monitoring in head-injured patients.

Continuous regional cerebral cortical blood flow (rCoBF) was monitored with thermal diffusion flowmetry in 56 severely head-injured patients. Adequate, reliable data were accumulated from 37 patients (21 acute subdural hematomas, 10 cerebral contusions, 4 epidural hematomas, and 2 intracerebral hematomas). The thermal sensor was placed at the time of either craniotomy or burr hole placement. In 15 patients, monitoring was initiated within 8 hours of injury. One-third of the comatose patients monitored within 8 hours had rCoBF measurements of 18 ml per 100 g per minute or less, consistent with previous reports of significant ischemia in the early postinjury period. Initial rCoBF measurements were similar in the patients with Glasgow Coma Scale scores of 3 to 7 and in those with scores of 8 or greater. In patients with poor outcomes, rCoBF measurements did not change significantly from initial measurements; however, in those patients who had better outcomes, final rCoBF measurements were higher than initial rCoBF measurements. The patients who had better outcomes experienced normalization of rCoBF during the period of monitoring, and patients with poor outcomes had markedly reduced final rCoBF. These changes were statistically significant. When management was based strictly upon the intracranial pressure, examples of inappropriate treatment were found. For example, hyperemia and increased intracranial pressure treated with mannitol caused further rCoBF increase, and elevated intracranial pressure with low cerebral blood flow treated with hyperventilation increased the severity of ischemia. In 3 (5%) of 56 patients, wound infections developed. Continuous rCoBF monitoring in head-injured patients offers new therapeutic and prognostic insights into their management.

Adolescent↗
PubMed1993

Hydroxychloroquine compared with placebo in rheumatoid arthritis. A randomized controlled trial.

OBJECTIVE: To assess the efficacy of hydroxychloroquine, 400 mg daily, for rheumatoid arthritis. DESIGN: Six-month, double-blind, randomized trial. SETTING: Ambulatory referral clinic in a Mexico City, Mexico, teaching hospital. PATIENTS: A total of 126 patients with early rheumatoid arthritis were randomly assigned to receive hydroxychloroquine, 400 mg/d, or placebo; 121 patients completed the study. RESULTS: Hydroxychloroquine showed a clinically and statistically significant improvement over placebo in joint score (20% greater mean improvement; 10% more patients improved by > 50%); pain (40% greater mean improvement; 19% more patients improved by > 50%); grip strength (22% greater mean improvement; 21% more patients improved by > 50%); patient global assessment (16% more patients stated they had improved); and physician global assessment (12% more patients were judged to have improved). Side effects were mild, and no patients in the hydroxychloroquine group required discontinuation of therapy. Patient compliance with the study medication was high. CONCLUSION: Hydroxychloroquine is moderately effective in early rheumatoid arthritis.

Adult↗
PubMed1993

Chest expansion in healthy adolescents and patients with the seronegative enthesopathy and arthropathy syndrome or juvenile ankylosing spondylitis.

OBJECTIVE: To determine chest expansion measurements in healthy children and those with juvenile spondyloarthropathies. METHODS: Chest expansion, as defined by the difference between maximal inspiration and maximal expiration was measured in 157 healthy adolescents (112 boys and 45 girls) aged 11 to 15 years, 20 patients with the seronegative enthesopathy and arthropathy (SEA) syndrome and 15 with juvenile ankylosing spondylitis (AS). RESULTS: The median and mean chest expansion (+/- 2 SD) were 5.0 cm and 5.6 cm (+/- 3.52) for the whole group of healthy adolescents, 6.0 cm and 5.9 cm (+/- 3.64) for boys and 5.0 cm and 4.8 cm (+/- 2.69) for girls. The frequency distribution of the values was leptokurtic and skewed to the right and did not follow the normal pattern; nearly 90% of the measurements fell within the interval from 3 to 9 cm. Of all variables analyzed (age, height, weight, sex and health/disease status), only height correlated with chest expansion (r = 0.20, p = 0.01). Even so, the effect of all these variables explained only 13% of the total variance of the measurements. Interobserver and intraobserver intraclass correlation coefficients were moderate (0.58 and 0.67, respectively). Mean values and cumulative frequency distribution in asymptomatic and symptomatic SEA syndrome and patients with juvenile AS were similar to those from healthy adolescents. CONCLUSION: Measuring chest expansion does not seem to be a useful method for the rare cases of early involvement of the chest joints in SEA syndrome and juvenile AS.

Adolescent↗
PubMedDate not supplied

Prevalence of hepatitis C virus among candidates for blood donation at the Hospital General de Mexico.

Among the NonA-nonB hepatitis, only hepatitis C is exclusively of parenteral transmission. The reported seroprevalence among blood donors in the world ranges from 0.5 to 6.0%. In order to discover the seroprevalence of anti-HCV in candidates for blood donation at the General Hospital of Mexico, 330 individuals were studied. Determination of anti-HCV was performed by the UBI HCV EIA diagnostic test. Risk factors such as history of major surgery, transfusions, drug addiction, etc were also assessed. There were only 4 seropositive patients (1.2%), 95% CI = (0, 2.75%). Only major surgery was associated with seropositivity. It was not possible to exclude hemotransfusion during surgery as a risk factor.

Blood Donors↗