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Biomedical subjects

A Rivera

Publications and source records attributed to A Rivera.

At least 109 records · Page 6Linked to original sources
PubMed1986

Lowering of pH does not directly affect the junctional resistance of crayfish lateral axons.

The effect of pH was tested on the junction between crayfish lateral axons. By means of a glass capillary inserted into one of the axons, one side of the junction was perfused with solutions of known pH while the junctional resistance, Rj, was monitored. Integrity of the gap junction was checked electron microscopically. Rj remained unchanged when the pH of the perfusate was lowered from 7.1 to 6.0. However, when the pH of the unperfused side of the junction was lowered by substituting acetate for chloride in the external solution, Rj rose, attesting to the integrity of the junction and its capacity to uncouple in the perfused state. We suggest that H+ does not affect the junctional channels directly, but acts through an intermediary which is inactivated or removed by the perfusion.

Animals↗
PubMed1983

Eradication of scabies with a single treatment schedule.

A single application (16 to 20 hours) of 1% gamma benzene hexachloride (GBH) lotion, when applied to a total island population of 178 persons in which seventy-four clinically had scabies, resulted in a cure rate of over 98%. Re-examination of the population at 10 and 21 weeks revealed only one remaining individual still having scabies. On a neighboring island, only those with clinical evidence of scabies were treated (140 persons). Applications of 1% GBH lotion were applied with the same methods used on the first island. When the population was re-examined at 10 weeks, the prevalence of scabies was reduced by only 50%. Successful eradication of scabies from a population should include treatment of all contacts, whether clinically infected or not. Treatment of the entire population at risk at one time is preferable. Coexistent pyoderma should be treated, and a second treatment for scabies may be needed when the pyoderma has cleared.

Administration, Topical↗
PubMed1983

A comparative trial of three treatment schedules for the eradication of scabies.

A trial of three treatment schedules, consisting of 1% gamma benzene hexachloride (GBH) lotion applied head to toe and left on the body for 2, 6, or 12 to 24 hours was conducted on an island of 2,076 persons, approximately 70% of whom had clinical evidence of scabies. The island is situated off the north coast of the Republic of Panama. Examination at 1 month after therapy showed that both the 6-hour and 12- to 24-hour cure rate was high (96% and 98%). There was a significantly lower cure rate in the 2-hour group, in which only 82% were cured. Eleven to twelve percent of the subjects became infested in all groups, presumably due to contact with untreated persons with scabies on the island. A single 6-hour application of 1% GBH lotion appears to be adequate therapy for scabies if properly applied. The entire population at risk should be treated at the same time if possible to reduce or eliminate the risk of infestation. No adverse reactions to 1% GBH lotion were observed.

Administration, Topical↗
PubMed1975

Changes in tissue glycogen of recovering asphyxiated newborn monkeys.

Newborn rhesus monkeys were used to investigate the relation between the duration of total asphyxia and the magnitude of the postasphyctic cerebral glycogen hyper-deposition response. The latter has been observed to occur following episodes of total asphyxia lasting 12.5 min and to be maximal at 12 h into the recovery period. The changes in glycogen contents of other vital organs were also studied. A minimum duration of 9 min of total asphyxia was required for the first elicitation of the cerebral glycogen hyperdeposition response. The magnitude of the response once elicited did not vary whatever the duration of the asphyxia beyond 9 and up to 30 min. During the actual episodes of total asphyxia, the glycogen content of the brain diminished more rapidly and completely than did that of kidney or heart. The hepatic, pulmonary and muscle glycogen contents did not change significantly either during asphyxia or during the recovery period.

Animals↗
PubMedDate not supplied

Distinct quality of depressed mood: an attempt to develop an objective measure.

Since the time of Kraepelin, in continental Europe the sadness of depression has been considered to have a "distinct quality' basic to the diagnosis of pathological depression. This distinct quality has been interpreted by observers but patients have been noted to have difficulty verbalizing differences from normal sadness. The authors have used a discriminant analysis to study how patients define pathological sadness and as a result have developed a Pathological Sadness Index with a sensitivity of 0.94, a specificity of 0.96 and a total misclassification rate of 5% (kappa w = 0.90).

Adjustment Disorders↗
PubMedDate not supplied

Mass chemotherapy for intestinal Taenia solium infection: effect on prevalence in humans and pigs.

Mass treatment of the human population with niclosamide was carried out in 2 villages in rural Guatemala where Taenia solium was endemic, to determine how this would affect the epidemiology of the parasite. Intestinal taeniasis was diagnosed by microscopy and coproantigen testing, and porcine cysticercosis by a specific Western blot. Before mass treatment, the prevalence of human taeniasis was 3.5%; 10 months after treatment it was 1%, a significant decrease (P < 10(-4)). All tapeworms that could be identified to the species level were T. solium. Similarly, the seroprevalence of antibodies to cysticercosis in pigs declined from 55% before treatment to 7% 10 months after treatment, once again a significant decrease (P < 10(-6)). These effects were seen in both villages. The possible use of mass chemotherapy as a tool in the control of T. solium is discussed.

Animals↗
PubMedDate not supplied

Refined mapping of the gene encoding the p127 kDa UV-damaged DNA-binding protein (DDB1) within 11q12-q13.1 and its exclusion in Best's vitelliform macular dystrophy.

Best's vitelliform macular dystrophy (Best's disease) is an autosomal dominant disorder of unknown causes and is typically characterised by an accumulation of lipofuscin-like material in the subretinal space of the macula. The disease gene has been localised to chromosome 11q12-13.1 within a 1.4 Mbp interval flanked by markers at D11S1765 and uteroglobin (UGB). Here we report the refined mapping of the gene encoding the p127 kDa subunit (DDB1) of a UV damage-specific DNA binding protein within the D11S1765-UGB region. Northern blot analysis demonstrates an abundant expression of the DDB1 transcript in the retina suggesting a functional role for DDB1 in this tissue. These considerations together with the chromosomal localisation have led us to evaluate the possible involvement of DDB1 in the pathogenesis of Best's disease.

Base Sequence↗