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Biomedical subjects

A Rivera

Publications and source records attributed to A Rivera.

119 records · Page 7Linked to original sources
PubMedDate not supplied

Value of electron microscopy in the diagnosis of childhood nephrotic syndrome.

The value of the ultrastructural study of the renal biopsy was investigated in a series of pediatric patients with nephrotic syndrome. Forty-eight cases of renal biopsies with clinical data were reviewed and divided into diagnostic groups. The contribution of electron microscopy to the final diagnosis was graded as essential-diagnosis could not be reached without it; supportive-it increased the level of confidence in the final diagnosis; and noncontributory. In this series of renal biopsies from 48 children with nephrotic syndrome resistant or nonresponsive to therapy, the most frequent diagnosis was minimal change disease, present in 42% of the patients. The contribution of the electron microscopic study to the final diagnosis was essential in 73% of the series, and was supportive in a further 27%. Therefore, it is concluded that the ultrastructural study was an essential component in the study of the renal biopsy in children with nephrotic syndrome, suggesting that electron microscopy needs to continue to be performed for all these patients.

Adolescent↗
PubMedDate not supplied

Volume transmission and wiring transmission from cellular to molecular networks: history and perspectives.

The present paper deals with a fundamental issue in neuroscience: the inter-neuronal communication. The paper gives a brief account of our previous and more recent theoretical contributions to the subject and also reports new recent data that support some aspects of our proposal on two major modes of communication in the central nervous system: the wiring and the volume transmission. There exist two competing theories on inter-neuronal communication: the neuron doctrine and the theory of the diffuse nerve network, supported by Cajal and Golgi, respectively (see their respective Nobel Lectures). The present paper gives a brief account of a view on inter-neuronal communication in the brain, the volume and wiring transmission concept that to a great extent reconcile these two theories. Thus, the theory of volume and wiring transmission are summarized and its recent developments that allow to extend these two modes of communication from the cellular network to the molecular network level is also briefly illustrated. The explanatory value of this broadened view is further enhanced by our recent proposal on the existence of a Global Molecular Network enmeshing the entire central nervous system. It may be interesting to note that also the Global Molecular Network theory is reminiscent of the old reticular theory of Apathy. Finally, the so-called 'tide hypothesis' for diffusion of signals in the brain is briefly discussed and its possible extension to the molecular level is for the first time introduced. Early indirect evidence supporting volume transmission in the brain was the discovery of transmitter-receptor mismatches. Thus, as an experimental part of the present paper a new approach to evaluate transmitter-receptor mismatches is given and evidence for inter-relationships between temperature micro-gradients and mismatches is provided.

Cell Communication↗
PubMedDate not supplied

In vivo biliary function in the adult rat: the effect of parenteral glucose and amino acids.

Parenteral glucose and glucose-amino acid mixtures are used in the nutritional support of infants, children, and adults when enteral feedings are precluded for any reason. During the first week of such nutritional support, the total energy intakes are generally low and glucose and electrolytes are the only nutrients provided. To assess the effects of such "hypocaloric" regimens, we determined the hepatic responses to parenteral infusions of either glucose or glucose-amino acid mixtures in rats. Further, to illustrate the magnitude of these changes in comparison to normally fed animals, we included a group of sham-operated, chow-fed rats. Bile flow, biliary bile acid output, bile osmolarity, serum bile acids, and plasma amino acids were measured in adult rats following 5 days of the respective dietary regimens. Liver histology was also assessed. Bile acid output, but not bile flow, was significantly decreased by the infusion of glucose compared to glucose-amino acid mixtures. However, in comparison to the chow-fed rats, bile acid output was significantly reduced in both groups of parenterally fed animals, whereas bile flow was significantly reduced only in the glucose-infused animals. Plasma amino acids were markedly different between the groups; concentrations of essential amino acids were greater in the glucose-amino acid infused animals than in the glucose infused animals. Nonessential gluconeogenic amino acids were significantly higher in the glucose-infused animals compared to the other groups; plasma valine was significantly lower in the glucose-infused animals reflecting the lack of protein intake. Liver histology was markedly abnormal in all of the glucose-infused animals, whereas only half the glucose-amino acid infused animals had abnormal pathology.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMedDate not supplied

A technique for intravenous nutrition in the newborn rabbit.

A technique and nutritional regimen for intravenous feeding of neonatal rabbits is described. Central venous nutrition of 40- to 60-g newborn rabbits was accomplished in a modified infant incubator using a specially constructed catheter and light-weight harness to provide nutrients by central vein for periods up to 7 days. Throughout the infusion period the newborn rabbits appeared healthy and evidenced increasing activity with age. The pups grew an average of 6.3 g/day, while receiving an intake of 150 to 200 kcal/kg/day. This model appears capable of being utilized to provide information on neonatal growth and metabolism in response to parenteral nutrition.

Animals↗
PubMedDate not supplied

Technetium-99m sestamibi in the diagnosis of breast cancer. The Mayagüez Medical Center experience.

The most successful screening procedures for breast cancer are breast physical examination and mammography. However, mammography has a positive predictive value of 15-30% for nonpalpable malignancy and of 22% for palpable carcinoma; this results in a large number of biopsies on patients with benign lesions. Furthermore, the benefit of mammography in woman with dense breast tissue (< 50 years old) has been questioned. Different studies have shown that Scintimammography with Tc-99m has a high sensitivity and specificity for detecting breast cancer (average of 85% and 89%, respectively), with higher positive predictive value for palpable lesions (89%). We reviewed retrospectively 35 records of patients that had Scintimammography in our institution, and the sensitivity, specificity, positive and negative predictive values were similar to other centers (100%, 76%, 62.5% and 100%, respectively). So, Scintimammography may be a complement for current diagnostic techniques for breast malignancy in our setting.

Breast↗
PubMedDate not supplied

Nursing intervention in a disaster.

In October 1985, Puerto Rico was struck by disaster. Two of the nurses who were part of the health team wrote about their experience and what they learned.

Crisis Intervention↗
PubMedDate not supplied

A pilot study to collect micro-activity data of two- to four-year-old farm labor children in Salinas Valley, California.

A pesticide exposure assessment pilot study was conducted in Salinas Valley, California during September, 1993. The pilot study had two main purposes: 1) to develop general methodologies for videotaping micro-activities of a population, and 2) to collect an initial database of activity patterns of two- to four-year-old farm labor children. Tools to accurately determine exposure and dose through all three pathways (dermal, ingestion, and inhalation) are needed to effectively assess and manage health risks posed by pesticides and other environmental pollutants. Eight to ten hours of videotape data were collected for each of four Mexican-American farm labor children. In addition, the researchers administered a day-after recall questionnaire to the caregivers of the children to test (for the study sample) the hypothesis that recall questionnaires are inadequate for collecting detailed information regarding dermal and hand-to-mouth exposures. The results of this study provide the first detailed set of videotape data on farm labor children, a population at high risk to pesticide exposures. In addition, this is the first project in the exposure assessment field to use direct observation videotaping for collecting micro-activity data in order to quantify dermal and ingestion exposure. The comparison of caregivers' recall of children's activities to actual videotapes from the pilot study supports the hypothesis that videotaping may greatly improve the accuracy of activity information used to compute dermal and ingestion exposures. However, as it was clear that the researchers' presence in some cases altered the activities of the subjects, further experiments need to be conducted to minimize interference of videotaping on exposure-related activities. This paper explains the selection of the study population, the methods used to implement the pilot study, and the lessons learned. While the discussion focuses on four case studies in the Mexican-American farm labor population, the data collection methods developed and the lessons learned can be applied to other populations.

Activities of Daily Living↗