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Biomedical subjects

M Rojas

Publications and source records attributed to M Rojas.

At least 181 records · Page 10Linked to original sources
PubMed1977

[Methylation of tRNA in Carcinus maenas gonadal cultures: inhibition by purified androgenic gland extract].

Subcultures of ovaries and testis of the crab Carcinus maenas have been performed in the presence of L-[Me-14C]methionine. Introduction in the medium of a chromatographically-purified liposoluble fraction from the androgenic glands of the same animal inhibits the biological methylation of the tRNA of the ovaries by 62%. The inhibition of methylation of five individual bases varies from 45% to 84%. No inhibition of tRNA methylation is observed under the same conditions with testis subcultures.

Animals↗
PubMed1976

The effect of water, sodium overloading and diuretics upon urinary kallikrein.

The effects of acute administration of either water or 2% NaCl solution via a stomach tube and injections of diurecits, furosemide (5, 10 mg) and acetazoleamide (5, 20 mg per rat), in adult rats upon urinary kallikrein (Kal), Na and K, were studied. Hyperhydration with water (5% b.w.) produced in 121% increase and 2% NaCl overloading (5% b.w.) 275% increase in urinary Kal within 120 min after gavage, when compared with the excretion of non hyperhydrated rats. Furosemide 5 mg in hyperhydrated animals produced in the same period an excretion of 645 +/- 52 ng BR of Kal, which is 147% higher to that excreted by the hyperhydrated controls. The same dose of furosemide in 2% NaCl loaded rats, produced an excretion of Kal equivalent to 1333 +/- 72 ng BR which is 180% greater than in controls similarly loaded. Acetazoleamide 20 mg and furosemide 5 mg produced similar excretions of Kal even though natriuresis is greater tna kalliuresis is lesser in furosemide injected rats. Evaluation of total kidney Kal has shown that a single (10 mg) or a series of furosemide injections (8 days 5 mg + 1 day 10 mg), brings about a significant (p is less than 0.001) decrease in renal Kal, but the increase of Kal excreted in the urine (120 min) is 3.5 times more (under a single injection) and 42 times more (under 9 injections) than the amount which disappears from the kidneys. Apparently furosemide not only stimulates Kal excretion, but also Kal synthesis in the kidney. The results support the concept that the Kal system would be involved in excretory functions dealing both with sodium and water excretion.

Acetazolamide↗
PubMed1976

Renal urinary kallikrein in normotensive and hypertensive rats during enhanced excretion of water and electrolytes.

1. Urinary kallikrein excreted by normal rats is significantly increased (P less than 0-001) 2 h after: (a) water loading, (b) water loading plus frusemide, 0-27 mmol (10 mg) per rat, (c) salt loading. In water-loaded rats, 5 i.u. of renin strikingly reduced kallikrein excretion (P less than 0-01) but considerably increased sodium excretion (P less than 0-001). 2. Renal kallikrein, measured by its kininogenase activity within 2 h of water loading, was significantly increased (P less than 0-05); after water loading and frusemide it was 40% decreased (P less than 0-001) and after salt loading it was reduced by approximately 50% (P less than 0-02). Renin did not change renal kallikrein. 3. Severely hypertensive (one-kidney) rats (blood pressure greater than 150 mmHg) showed no increase of urinary kallikrein after water loading, although there was a marked natriuresis, in moderately hypertensive rats (blood pressure less than 150 mmHg) urinary kallikrein was only one-third of that observed in control normotensive rats, after an equal degree of water loading.

Animals↗
PubMedDate not supplied

[Trihalomethanes in the drinking water of Carabobo State, Venezuela].

OBJECTIVE: Disinfection of water with chlorine in water treatment plants leads to the formation of trihalomethanes (THMs). These compounds are associated with adverse health effects. The aim of this study was to analyze THM concentrations in the water provided for human consumption in the two main water treatment systems of Carabobo State: the Alejo Zuloaga plant and the Pao-Cachinche reservoir, which form the Central Regional System I (CRS I), and the Lucio Baldo Soules plant and the Pao-La Balsa reservoir, which form the Central Regional System II (CRS II). METHODS: We analyzed 144 water samples collected in 6 samplings carried out in 2000 and 2001. THM concentrations were determined by gas chromatography using the headspace technique. The concentrations of the following THMs were measured: chloroform (CHCl3), bromoform (CHBr3), chlorodibromomethane (CHBr2Cl) and bromodichloromethane (CHCl2Br). RESULTS: The concentration of total THMs was between 47.84 g/l and 94.23 g/l. CHCl3 was the most commonly formed compound representing 83% of all THMs in the CRS I and 82% in the CRS II. The concentrations of total THMs in the CRS I, specifically in the Baja and San Diego networks, were significantly higher (p < 0.05) than permissible levels set by the American Environmental Protection Agency (80 g/l) for the sum of all four THMs. CONCLUSIONS: The results show that in the area studied there is a risk of adverse health effects due to THMs in drinking water, especially in the Baja and San Diego networks.

Chlorine↗
PubMedDate not supplied

[Geographic differences in mortality from digestive tumors in Spain, 1980-1984].

The purpose of this study is to analyze the geographical distribution of eight gastrointestinal (GI) cancer sites in Spain, during the 1980-1984 period. Data for deaths attributed to each cancer site were obtained from Spain's National Institute for Statistics (INE). Standardized Mortality Ratios (SMR) were calculated for each GI cancer site, using the International Classification of Diseases (ICD) 9th revision. Statistical tests were performed to determine whether SMR's were statistically significant. The mortality distribution for cancers of the oropharynx and oesophagus showed a similar pattern, which might suggest some common risk factor in their etiology. Stomach cancer presented high SMR's in the northern central areas (Meseta). Colon, rectum and pancreas cancer sites emerged with irregular patterns though high SMR's were more often observed in developed areas within the country.

Cluster Analysis↗
PubMedDate not supplied

Pesticide exposure in a farming village in Venezuela--a developing country.

This study was designed and performed by the Universidad de Carabobo, Centro de Investigaciones Toxicológicas, Venezuela, and the University of Cincinnati Department of Environmental Health. The authors tested methodology and analyzed preliminary data on demographics, pesticide use, health, environment, and lifestyles in a farming community in Venezuela (population = 386; sample size = 81) to determine if pesticide misuse might have been contributing to public health problems. Questionnaire and geographic information were collected. There were statistically significant incidences of pesticide-related symptoms (p < .01) in farmers versus nonfarmers (odds ratio = 5.7; 95% confidence interval = 2.9, 18.8). In addition, in one area there was a cluster of farmers who experienced symptoms that appeared to be the result of foul air and proximity to farms where there was pesticide use. The results of the study indicated that this public health problem may have been associated with pesticide misuse; however, additional studies are needed to corroborate the findings.

Adolescent↗
PubMedDate not supplied

The use of quality indicators for assessing radical prostatectomy specimens.

The information contained in pathology reports of radical prostatectomy specimens is critically important to treating physicians for selecting adjuvant therapy, evaluating therapy, estimating prognosis, and analyzing outcomes. This information is also of importance to patients and their families. In recent years, the Cancer Committee of the College of American Pathologists and the Association of Directors of Anatomic and Surgical Pathology developed suggested protocols for reporting the findings on radical prostatectomy specimens. The objectives of this study were to assess radical prostatectomy-specimen reports by using quality indicators derived from existing suggested protocols and to thereby assist pathologists in improving the quality of their reports on such specimens. A retrospective chart review of 554 cases for the second 6-month period of 1996 focused on 10 quality indicators: submission of a frozen section; location of the adenocarcinoma; proportion of the specimen involved by adenocarcinoma; perineural involvement; vascular involvement; seminal vesicle involvement; periprostatic fat status; number of nodes submitted; status of nodes; and prostate intraepithelial neoplasia (PIN). The findings of this study were shared with the pathology departments in all hospitals in New York State. In addition, the 113 hospitals from which the 554 cases were drawn were given their institution-specific data. Teleconferences were held with the 37 hospitals that accounted for 72.4% of all cases. These conferences included directors of pathology and laboratories and focused on the aggregate statewide findings. The presence of quality indicators in reports varied from a mean of 14.8% (periprostatic fat) to a mean of 85.9% (seminal vesicle involvement). For all hospitals, 4 indicators (proportion of the specimen involved by adenocarcinoma, vascular involvement, periprostatic fat status, and PIN) were included in fewer than 50% of cases. These 4 quality indicators and an additional 3 others (submission of a frozen section, perineural involvement, and the number of nodes submitted) were included in fewer than 70% of cases. Only 3 indicators (location of the adenocarcinoma, seminal vesicle involvement, and the status of nodes) were found in more than 70% of cases. Although the mean level of quality indicator inclusion ranged from 14.8% to 85.9% for all cases examined, the absolute range for any individual indicator was 0% to 100%. Thus, some hospitals included a given indicator 100% of the time; others never included it. This pattern held true for all 10 indicators. High-volume hospitals (10 or more cases) performed significantly better than low-volume hospitals (1-4 cases) on 5 indicators (P < .05), and better, but not significantly so, for an additional 2 indicators. Overall, the mean inclusion levels for all 10 indicators were 10% higher for high-volume hospitals compared with low-volume and medium-volume hospitals (5-9 cases). This study demonstrated wide variations in the inclusion of quality indicators by pathologists in their radical prostatectomy-pathology reports. Whereas some hospitals always include given indicators, others never mentioned them. These marked disparities point to the need for standardized reporting for radical prostatectomy specimens.

Age Distribution↗
PubMedDate not supplied

The CEA family: a system in transitional evolution?

The CEA family consists of two structurally and functionally distinct sub-groups; the group including CEA, NCA and CGM-6 which are cell surface-bound by phosphatidyl-inositol (PI) linkages, and the group of BGP splice variants which have trans-membrane and cytoplasmic domains. Although all CEA family members mediate intercellular adhesion in vitro, the PI-linked group show Ca++ and temperature independent adhesion whereas the BGP group show rapidly reversible Ca++ and temperature dependent adhesion. From the close alignment in cDNA nucleotide sequences between family members and between repeated domains in one family member, it is apparent that the CEA family is now rapidly evolving; in fact, analogs of only the trans-membrane BGP group have been found so far in the mouse. The addition of a new group of potent adhesion molecules to complex species at some time after the rodent radiation has strong evolutional implications, which are discussed.

Animals↗
PubMedDate not supplied

Morphological evidence by scanning electron microscopy of excretion of metacyclic forms of Trypanosoma cruzi in vector's urine.

Comparison by scanning electron microscopy (SEM) of Trypanosoma cruzi flagellates attached to the cuticle of the rectal gland of infected Dipetalogaster maxima nymphs, showed marked differences before and after feeding. Before feeding numerous metacyclic trypomastigotes were observed among the abundant epimastigotes that formed the carpet of flagellates. On the other hand, in insects that were allowed to urinate for 24 hours after a meal, the metacyclics were scarce, indicating that they had been detached by the urine flow. An asymmetric type of cell division, probably originating both an epi- and a trypomastigote, was occasionally observed. The occurrence of swellings at different levels of the flagella of epimastigotes suggests that secondary sites of attachment may be common.

Animals↗