Velocity measurements in a convective flow by holographic interferometry

A holographic interferometry technique has been developed that can be used to measure the three components of the velocity field in a whole plane of a fluid flow simultaneously. The light scattered from an illuminated fluid plane is recorded on a hologram. Several interferograms are obtained in the reconstruction of the hologram. Each interferogram is automatically analyzed and produces quantitative information about one velocity component. Parameters that affect the quality of the interferograms are analyzed. The technique is demonstrated in a Rayleigh-Bénard convective flow. Holographic interferometry and particle image velocimetry techniques are compared.

Overweight and hypertension: data from the 1992-1993 Mexican survey

Data of the 1992-1993 Mexican Survey of Chronic Diseases in the Urban Adult Population were analyzed to investigate the effects of age and sex on the association between overweight and hypertension. Blood pressure, body weight, and height were measured in a group of 13,945 Mexicans aged 20 to 69 years living in towns and cities larger than 15,000 people. Hypertension was defined following the recommendations of the Joint National Committee for Detection, Evaluation, and Treatment of High Blood Pressure-V. Overweight was defined following the recommendations of the National Institutes of Health Consensus on Health and Obesity. The prevalence of types of hypertension was higher in men than in women, particularly in the groups of 20 to 39 years of age. Cross-classification of subjects according to the presence of hypertension and overweight confirmed the association between both variables. The odds ratio and 95% confidence intervals indicated that overweight was associated with systolic and diastolic hypertension and with isolated diastolic hypertension in women and, to a lesser extent, in men. This association was not found in the 60- to 69-year group in both sexes. Overweight did not show significant association with isolated systolic hypertension in both sexes. Results of a multiple logistic regression analysis of overweight on hypertension, controlling for age and sex, were consistent with these findings. It is suggested that other factors, independent of overweight, explain the observed gender-specific differences in the prevalence of hypertension in younger age groups. The hormonal environment of young women is one of the mentioned factors modifying the prevalence of hypertension in this group of the Mexican urban adult population.

[Coverage of Mexican articles and journals in the database Bibliomex Salud]

OBJECTIVE

To evaluate the coverage of Mexican journals and manuscripts of biomedical research in a Mexican data base (Bibliomex Salud) during its 10 years of existence (1985-1994).

MATERIAL AND METHODS

All the manuscripts published by a single Mexican journal Revista de Investigación Clínica (RIC) were searched for in Bibliomex: the absence of a RIC manuscript in Bibliomex was considered a failure. Also, the number and identity of the Mexican journals included in Bibliomex was also noted. From a total of 744 manuscripts 99 were excluded (22 non-Mexican, 25 nonindexable, and 52 initially not indexed by Bibliomex). The remainder (645) were classified according to starting year of indexing: originals since the first year; letters to the editor since 1990; and editorials and authors' replies since 1993.

RESULTS

Bibliomex started out with 21 Mexican journals and now has more than 50 (12 indexed during the 10 years, 27 for the last 5-9 years, and 16 for the last 1-4 years). Regarding manuscripts, Bibliomex had an 8% failure rate in originals (46/597) and letters (3/36), and 25% in editorials and authors' replies (3/12).

CONCLUSIONS

a) The coverage of Bibliomex has improved in its second half of life in the number of both journals and manuscripts indexed; b) the retrieval of information could be improved by two changes in the procedures of Bibliomex; c) Bibliomex seems to be a database which could be used to analyze Mexican research production at several levels (institutional, regional, and national).

The therapeutic approach to the control of hypertension. Its impact on health policy

The pharmacologic approach to the control of hypertension must consider both the clinical perspective and the Public Health approach policy in which social costs have to be balanced against benefits to the entire population. Cost-effectiveness analysis are at the core of decisions taken within this frame of reference. The issue of cost-effectiveness of preventive and therapeutic measures are crucial in the case of less developed countries. An analysis of studies undertaken in Mexico leads to the conclusion that, from a Public Health perspective, a program for the control of hypertension with a strong emphasis on drug therapy is likely to require a significant proportion of the health budget. Therefore, more emphasis must be placed on primary prevention based on modifications of life style.

Parity and the prevalence of overweight

OBJECTIVE

To assess the association between previous term pregnancies and the prevalence of overweight in a group of urban women, controlling for the influence of age.

METHODS

One thousand twelve women, living in middle and low socioeconomic areas of Mexico City, were interviewed at home and their reproductive histories studied. Height and weight were measured in a clinical setting using controlled procedures. Overweight (BMI > 25) was the dependent variable used to calculate odds ratios and to perform a multiple logistic regression analysis.

RESULTS

Age and parity were significantly associated with the prevalence of overweight. Controlling for age, two or more previous pregnancies significantly increased the magnitude of the association.

CONCLUSION

During the reproductive years parity seems to increase the risk of overweight in low and middle socioeconomic level urban women.

[Erythrocyte transketolases and Alzheimer disease]

Abnormalities of thiamin metabolism have been reported in senile dementia of Alzheimer's type (SDAT). Transketolases (TK) were studied in 21 patients with SDAT, 24 age-matched controls and 12 chronic alcoholics. Erythrocytes were assessed for their TK activity coefficient (TK-AC, normal value 8.4 +/- 12.6%) and affinity for thaimin pyrophosphate (Km TPP, normal value 17.8 +/- 8.3 mumol). Comparison between study groups and controls demonstrated increased TK-AC in SDAT (16.6 +/- 15.7%, P < 0.05) and chronic alcoholism (43.4 +/- 40.6%, P < 0.05), and increased Km TPP (38.3 +/- 25.2 mumol, P < 0.01) in SDAT only. These findings suggest structural abnormalities of TK rather than vitamin B1 deficiency in SDAT.

Effects of magnesium, high energy phosphates, piracetam and thiamin on erythrocyte transketolase

Erythrocyte transketolase activity coefficient (ETK-AC) and affinity for coenzyme (Km TPP) were assessed in 50 patients with transketolase abnormalities such as fibromyalgia or senile dementia of Alzheimer's type, before and after magnesium (Mg), thiamin+pyridoxine (B1,B6), high energy phosphates (HEP) (phosphocreatinine of adenosine triphosphate), and piracetam. Compared to 12 untreated patients, ETK-AC was significantly decreased with B1,B6 (P < 0.05, n = 10); Km-TPP was significantly decreased with HEP (P < 0.05, n = 20) and piracetam (P < 0.01, n = 5). In nine other patients treated with HEP + B1,B6 + magnesium, ETK-AC and Km TPP were both significantly decreased.

Prospective study of infection, colonization and carriage of methicillin-resistant Staphylococcus aureus in an outbreak affecting 990 patients

In the three years between November 1989 and October 1992, an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) affected 990 patients at a university hospital. The distribution of patients with carriage, colonization or infection was investigated prospectively. Nosocomial acquisition was confirmed in at least 928 patients, 525 of whom were identified from clinical specimens as being infected (n = 418) or colonized (n = 107) by MRSA. An additional 403 patients were identified from screening specimens, of whom 58 subsequently became infected and 18 colonized. Screening of the nose, throat and perineum detected 98% of all carriers. Of the 580 infections in 476 patients, surgical wound, urinary tract and skin infections accounted for 58% of the infections. Of the 476 infected patients, death was attributable to MRSA infection in 13%. Colonization with MRSA was found in 127 patients and 42% of 165 colonized sites were the skin. Auto-infection from nasal carriage or cross-infection, probably via staff hands, seemed to be the most common mode of acquisition of MRSA infections.

[Organ transplantation as a health priority in developing countries]

The epidemiology profile of developing countries is in transition. While the prevalence of infectious and preventable diseases, malnutrition, and in general the health problems traditionally associated to the poor, is still high, the characteristic health profile of industrialized countries (i.e. chronic and degenerative diseases, accidents, violence, social pathology) is beginning to surface. This paper focuses on the need to consider organ transplantation as a health priority in developing countries, as an important element in the global strategy to cover both aspects of the health care demand.

Nd-YAG laser applications in surgical endoscopy: a single center comprehensive experience

A retrospective review of endoscopic procedures using the Nd-YAG laser was carried out for patients treated between September 1984 and November 1986. Two hundred twenty two procedures were performed on 104 patients (58M:46W) during this 26 month period. The study encompasses a unique period of time in this center, as it includes the initial use of the endoscopic laser technique, the learning curves associated with its application, and finally, the time when its use became routine. Treatment of tumors was the indication in 47 per cent of the cases. Gastrointestinal bleeding of benign cause was the indication in nearly half of the patients; arteriovenous malformations were the most common causes of bleeding. Laser photocoagulation of hemorrhoids was performed in 11 cases. Upper endoscopy was the route in 33 per cent of procedures. Anoscopy, flexible sigmoidoscopy, and colonoscopy were the routes in the remainder. The time spent on the procedure and the energy delivered were found to be variables of the type of lesion and the endoscopic route. Nd-YAG laser endoscopy can be used safely and effectively for a variety of bleeding and obstructive gastrointestinal conditions. Appropriate certification for granting of privileges to laser endoscopists is of utmost importance.

Degranulatory action of estradiol on blood eosinophil leukocytes in vivo and in vitro

The degranulatory activity of estradiol was tested on blood eosinophil leukocytes in vivo and in vitro. Treatment of adult ovariectomized rats with 30 micrograms estradiol/100 g body wt. increased the percentage of degranulated eosinophils from 10% to about 70% at 6 or 24 h after treatment, and increased the rate of in vitro eosinophil degranulation of those eosinophils that were non-degranulated at the time of blood sample collection. The addition of estradiol to blood samples from untreated ovariectomized rats (0.05 micrograms/ml) increased the percentage of eosinophils degranulated in vitro at 1 h of incubation from 20% to near 60%. It is suggested that estrogen acts directly on the eosinophils, probably via specific hormone receptors. Considering the hypothesis that eosinophils are involved in the mediation of a group of responses to estrogen in the uterus, it is proposed that the hormone-induced degranulation of these cells may have physiological implications in the regulation of the intensity and duration of the eosinophil-mediated responses. In addition, estrogen-induced eosinophil degranulation may interfere with the action of eosinophils that have migrated to other target organs (lymphoid organs, etc.) under the action of other agents (glucocorticoid hormones, histamine, etc.) or conditions (immune reactions, etc.).

The importance of primary diagnosis in perinatal death

In a referral perinatal center a detailed study was made of all the perinatal deaths that occurred during 1 year; they were analyzed according to primary diagnoses on the basis of a classification by R. L. Naeye which included the placenta. This method points to the areas in which special efforts at prevention should be made, and it should become a reliable basis for comparison.

Placentas of small-for-dates infants: a small controlled series from Mexico City, Mexico

Thirty-five placentas of small-for-dates infants were compared with control placentas of normally grown infants. They were small by weight, area, and volume and tended to have a marginal cord insertion; marginal cord insertion was associated with a thick cord, and central insertion, with a thin cord. When the two groups were compared, the first showed increased fibrinoid deposits and atherosis, more severe fetal abnormalities, and abnormal nutrition in the mother, together with a high incidence of preeclampsia. In the mothers of both groups, peak diastolic blood pressure was lower than that in the control group; additional factors leading to a probable reduction in placental blood flow were different in the two groups.