Biomedical subjects

A R da Silva

Publications and source records attributed to A R da Silva.

At least 19 recordsLinked to original sources

PubMed2000

Quantification of crotamine, a small basic myotoxin, in South American rattlesnake (Crotalus durissus terrificus) venom by enzyme-linked immunosorbent assay with parallel-lines analysis.

Intraspecific variation in Crotalus durissus terrificus venom composition was studied in relation to crotamine activity. Crotamine induces paralysis in extension of hind legs of mice and myonecrosis in skeletal muscle cells. To determine whether the venom of crotamine-negative rattlesnake contains a quantity of myotoxin incapable of inducing paralysis, we have developed a very sensitivity immunological assay method, an enzyme-linked immunoabsorbent assay (ELISA), capable of detecting 0.6 ng of purified crotamine. The parallel-lines analysis of ELISA data showed to be useful because it shows the reliability of the experimental conditions. A variation in the amount of myotoxin in the crotamine-positive venom was observed, but not less than 0.1 mg of crotamine per mg of venom. It was not possible to detect it in crotamine-negative venom even at high venom concentrations.

Animals↗

PubMed1997

Cloning and characterization of a repetitive 1.9 Kb HindIII DNA fragment from Crotalus durissus terrificus genome.

Eukaryote genomes are endowed with varying quantities of repeated DNA families. These families show different patterns of conservation among species, copy numbers, chromosomal distribution, and transcription. Characterization of repeated DNA sequences could help to understand the genome anatomy and organization or be used in molecular systematics and molecular evolution studies. We describe here a repetitive DNA sequence of the HindIII family present in the genome of the rattlesnake Crotalus durissus terrificus. In Brazil, the family Crotalus is comprised only by one species durissus, which include several subspecies. The number and distribution of these subspecies are controversial. In the present study, the genomic DNA of a female rattlesnake was digested with HindIII resulting in a strong 1.9 Kb band. A partial genomic library was constructed from the 1.9 Kb DNAs rescued from the agarose gel after HindIII digestion and ligated to the vector pGEM3Zf(+) (Promega). Analysis of 69 clones, 44 hybridized with the 1.9 Kb probe isolated from one of the clones-clone 76, indicating that the DNA isolated from this clone should represent the 1.9 Kb HindIII fragment. This 1.9 Kb HindIII DNA was completely characterized by sequencing.

Animals↗

PubMed1993

Comparative study on the efficacy and acceptability of two contraceptive pills administered by the vaginal route: an international multicenter clinical trial.

The efficacy and acceptability of two widely used oral contraceptive tablets, one containing 250 mg levonorgestrel and 50 micrograms ethinyl estradiol and the other containing 150 micrograms desogestrel and 30 micrograms ethinyl estradiol, administered by the vaginal route were compared in 1055 women studied over 12,630 woman-months of vaginal contraceptive pill use. This multicenter clinical trial was performed in nine countries of the developing world by the "South to South Cooperation in Reproductive Health," an organization founded by scientists from the Third World working in the area of reproductive health, and the study was developed and coordinated by one of these centers. The findings of this study confirm the efficacy of both these tablets when administered by the vaginal route. Involuntary pregnancy rates at 1 year of 2.78 for subjects in the levonorgestrel group and 4.54 for subjects the desogestrel group showed no statistically significant difference between the two groups. However, total discontinuation rates of 47.01 for subjects in the levonorgestrel group and 56.33 for subjects in the desogestrel group showed a statistically significant difference between the two groups, and discontinuation rates attributable to prolonged bleeding of 0.6 for subjects in the levonorgestrel group and 3.2 for subjects in the desogestrel group were also significantly higher in the group of subjects using the desogestrel vaginal contraceptive pill. Blood pressure remained at admission values throughout treatment. A statistically significant weight increase from admission values occurred in both groups of subjects.

Administration, Intravaginal↗

PubMed1993

Purification of basic fibroblast growth factor and alkaline phosphatase from human placenta.

Human placenta is an available hospital waste which is known to contain many valuable biochemicals that may be commercially exploited. Using placental tissue previously extracted for haemoderivatives, we purified basic fibroblast growth factor (bFGF), a soluble protein, and placental alkaline phosphatase (PALP), a membrane-linked protein, as a coupled process. bFGF purification comprises three steps: extraction and chromatographies on S-Sepharose and heparin-Sepharose. The final product includes a major 17 kDa and a minor 16 kDa component with a specific activity of 8.0 x 10(6) units/mg yielding 0.5-1.0 microgram/kg of placenta. PALP purification comprises four steps: acidic butan-1-ol extraction and chromatographies on Q-Sepharose, concanavalin A-Sepharose and Q-Sepharose. The purified PALP has a molecular mass of 70 kDa, a specific activity of 800 units/mg and yielded 50 micrograms/kg of placenta. The results show the possibility of purifying substances in placental haemolysed blood, soluble products from placental cellular mass and proteins from the cellular membrane in a one-stream process.

3T3 Cells↗

PubMed1984

Conception control by vaginal administration of pills containing ethinyl estradiol and dl-norgestrel.

One hundred twenty-four women of reproductive age have used vaginal pills containing 50 micrograms dl-norgestrel and 35 micrograms ethinyl estradiol to prevent conception for periods ranging from 6 to 20 months. One thousand four hundred thirty-eight woman-months were recorded. No pregnancies occurred. Cycle control was good. Bleeding usually lasted 3 to 5 days, and the interval between withdrawal bleeding events was 26 to 30 days in 86% of the cycles. Amenorrhea, breakthrough bleeding, and spotting occurred rarely. The continuation rate at 1 year was 64%.

Adolescent↗

PubMed1981

Long-term contraception with a single implant of the progestin ST-1435.

Silastic capsules containing the synthetic progestin ST-1435 was inserted in 282 women of reproductive age who desired long-term contraception. Each woman received a single implant for 6 months' use. After evaluating the experience of the first 45 subjects, replacement capsules were offered to women desirous of continuing the method after the initial 6 months of use. In the first 6-month segment one pregnancy and 1720 woman-months of use were recorded. The total experience, through as many as six segments of use was 3373 woman-months of use and one pregnancy. The Pearl Index is 0.36 per 100 woman-years. The single pregnancy, recorded in the 1st month of the first segment, may represent a conception prior to implant placement. Amenorrhea was the most common side effect reported, with 83% of the women having at least one nonbleeding interval longer than 60 days during the first segment of use.

Amenorrhea↗

PubMed1978

Contraception with long acting subdermal implants: I. An effective and acceptable modality in international clinical trials.

This paper presents results of a double blind, multi-centered and multi-national study of two progestin only subdermal implants used for contraception. A regimen of six capsules of levonorgestrel (Ng) used by 492 women had a net cumulative 12-month pregnancy rate of 0.6 percent and a continuation rate of 74.6 percent. 498 women used six capsules of norgestrienone (R2010) and experienced a net cumulative 12-month pregnancy rate of 3.5 percent and a continuation rate of 79.4 percent. The difference in the pregnancy rate was significant at P less than 0.01, while there was no significant difference in the continuation rates. Menstrual problems were the principal reason for termination of the levonorgestrel regimen, accounting for approximately half of all terminations. There were significantly fewer menstrual problems among users of the norgestrienone (R2010) capsules; the net cumulative 12-month termination rate for this reason was 4.3 percent. Results are compared with continuation and termination rates for acceptors of the Copper T 200 at the same clinics. The low pregnancy rate and reasonably high continuation rate of the norgestrel implants coupled with the fact that the expected effective lifetime of a set of capsules is of the order of 3-5 years appears to warrant further development of this contraceptive regimen.

Adolescent↗

PubMed1978