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Follicular development, ovulation, fertilization and fetal development in tenrecs (Tenrec ecaudatus).

Reproduction in female tenrecs was studied on Praslin Island (4 degrees 20'S, 55 degrees 45'E) in the Seychelles from November 1977 to September 1980. Dissection and histological examination of reproductive tracts revealed that each ovary is encapsulated in a bursa. Polyovular follicles were abundant and contained up to 5 oocytes. The occurrence of more implanted fetuses than corpora lutea (CL) indicated successful polyovuly in 25% of pregnancies. No antrum was observed during follicular growth at oestrus, and follicles were relatively small at maturation, reaching a maximum diameter of 570 microns. Ovulation involves a gentle extrusion of the granulosa and ovum into the periovarian space. Spermatozoa were abundant in the female reproductive tract including the periovarian space at oestrus. Spermatozoa penetrated the loosely-packed theca of mature follicles and were present in CL, indicating that intrafollicular fertilization may occur. The relatively small CL formed by eversion, reaching a maximum size after implantation. Fusion of up to four CL occurred in the ovaries of 41% of pregnant females. Polyovulation in the tenrec was confirmed by the occurrence of 10.4 +/- 0.5 (mean +/- s.e.m.) CL and 9.7 +/- 0.5 (mean +/- s.e.m.) implantations. Resorption occurred in 74% of 19 dissectable pregnancies, occurring in both uterine horns in 26% of pregnancies. Coefficients of variation in weights of fetuses in each litter were 10.0-26.8%, with the largest value corresponding to 273% variation in fetus weights. Litter size in the Seychelles tenrecs was smaller than in the same species in Madagascar (17.1 +/- 1.9 implantations) where the tenrec is native.

Animals↗

[Risk factors associated with acute myocardial infarction in the São Paulo metropolitan region: a developed region in a developing country].

OBJECTIVE: To identify the risk factors associated with acute myocardial infarction (AMI) and their respective powers of association in the São Paulo metropolitan region. METHODS: The cases comprised patients diagnosed with first AMI with an ST segment elevation. The controls were individuals with no known cardiovascular disease. The study comprised 271 cases and 282 controls from 12 hospitals. Risk factors were as follows: ethnic group; educational level; marital status; family income; family history of coronary artery disease; antecedents of arterial hypertension and of diabetes mellitus; hormonal replacement in women; smoking; physical activity; alcohol consumption; total cholesterol, LDL-cholesterol, HDL-cholesterol, triglyceride, and glucose levels; body mass index; and waist-hip ratio (WHR). RESULTS: The following risk factors showed and independent association with AMI: smoking [odds ratio (OR) = 5.86; 95% confidence interval (CI) 3.25-10.57; P < 0.00001); waist-hip ratio (first vs. third tertile) (OR = 4.27; 95% CI 2.28-8.00; P < 0.00001); antecedents of arterial hypertension (OR = 3.26; 95% CI 1.95-5.46; P < 0.00001); waist-hip ratio (first vs second tertile) (OR = 3.07; 95% CI 1.66-5.66; P = 0.0003); LDL-cholesterol level (OR = 2.75; 95% CI 1.45-5.19; P = 0.0018); antecedents of diabetes mellitus (OR = 2.51; 95% CI 1.45-5.19; P = 0.023); family history of coronary artery disease (OR = 2.33; 95% CI 1.44-3.75; P = 0.0005); and HDL-cholesterol level (OR = 0.53; 95% CI 0.32-0.87; P = 0.011). CONCLUSION: Smoking, waist-hip ratio, antecedents of arterial hypertension and of diabetes mellitus, family history of coronary artery disease, and LDL-cholesterol and HDL-cholesterol levels showed to be independently associated with AMI within the São Paulo metropolitan region.

Analysis of Variance↗

Applying principles of development to help at-risk preschoolers develop numeracy.

In a yoked control design, multicultural Head Start 4-year-olds played numerous games involving either numeracy or the oddity principle and insertions into series. Children showed better mastery of oddity and insertions after playing games directed at those two concepts. Numeracy scores on the McCarthy Scales of Children's Abilities (D. McCarthy, 1972) were equivalent for children who played numeracy games and children who played oddity and insertion games. These results are consistent with other research indicating that the understanding of oddity relations and that of insertions are key transitional thinking abilities that support numeracy at the preschool-kindergarten interface.

Child Development↗

Expression of somatostatin receptor genes and acetylcholine receptor development in rat skeletal muscle during postnatal development.

Our laboratory reported previously that somatostatin (SST) is transiently expressed in rat motoneurons during the first 14 days after birth. We investigated the possibility that the SST receptor (SSTR) is expressed in skeletal muscle. We found that two of the five subtypes of SSTR (SSTR3 and SSTR4) are expressed in skeletal muscle with a time course that correlates with the transient expression of SST in motoneurons. In addition, SSTR2A is expressed from birth to adulthood in skeletal muscle. Both SSTR2A and SSTR4 are also expressed in L6 cells, a skeletal muscle cell line. Somatostatin acting through its receptors has been shown to stimulate tyrosine phosphatase activity in a number of different tissues. We found that several proteins (50, 65, 90, 140, 180 and 200 kDa) exhibited a reduced degree of tyrosine phosphorylation following SST treatment. Inhibition of tyrosine phosphatase activity with sodium orthovanadate increased expression of the nicotinic acetyl-choline receptor (nAChR) epsilon subunit mRNA by three fold. Somatostatin reversed the elevated epsilon mRNA following orthovanadate treatment. These findings show that SSTR is expressed in skeletal muscle and that SST acting via the SSTR regulates tyrosine phosphorylation and expression of the epsilon subunit of the AChR in the rat skeletal muscle.

Animals↗

Antibody repertoire development in fetal and neonatal piglets. II. Characterization of heavy chain complementarity-determining region 3 diversity in the developing fetus.

Since the actual combinatorial diversity in the V(H) repertoire in fetal piglets represents <1% of the potential in mice and humans, we wondered whether 1) complementarity-determining region 3 (CDR3) diversity was also restricted; 2) CDR3 diversity changed with fetal age; and 3) to what extent CDR3 contributed to the preimmune VDJ repertoire. CDR3 spectratyping and sequence analyses of 213 CDR3s recovered from >30 fetal animals of different ages showed that >95% of VDJ diversity resulted from junctional diversity. Unlike sheep and cattle, somatic hypermutation does not contribute to the repertoire. These studies also revealed that 1) N region additions are as extensive in VDJ rearrangements recovered at 30 days as those in late term fetuses, suggesting that TdT is fully active at the onset of VDJ rearrangement; 2) nearly 90% of all rearrangement are in-frame until late gestation; 3) the oligoclonal CDR3 spectratype of 30-day fetal liver becomes polyclonal by 50 days, while this change occurs much later in spleen; 4) there is little evidence of individual variation in CDR3 spectratype or differences in spectratype among lymphoid tissues with the exception of the thymus; and 4) there is a tendency for usage of the most J(H) proximal D(H) segment (D(H)B) to decrease in older fetuses and for the longer D(H) segment to be trimmed to the same length as the shorter D(H) when used in CDR3. These findings suggest that in the fetal piglet, highly restricted combinatorial diversity and the lack of somatic mutation are compensated by early onset of TdT activity and other mechanisms that contribute to CDR3 junctional diversity.

Animals↗