Comparison between laparoscopic sterilization and tubal ligation.

During 1970-3, 1910 laparoscopic sterilizations and 531 tubal ligations were performed in Aberdeen. Common complications occurred with 61 (3.2%) and 99 (18.6%) of the operations respectively, but the pregnancy rate was much higher (2.2%) after laparoscopic sterilization.     

Female sterilization in Latin America: cross-national perspectives

Fertility levels have dropped substantially in Latin America in recent decades, fuelled by increased contraceptive use and notably a method mix skewed towards female sterilization. This study examined choice of female sterilization in four Latin American countries: Brazil, Colombia, the Dominican Republic and Peru. Data were drawn from national Demographic and Health Surveys conducted in 1995--1996. Discrete-time hazard models were used on the five-year calendar modules of women's reproductive histories to consider the effects of a number of sociodemographic and contextual determinants as they pertained to status at the moment of the event. The results revealed that the likelihood of a woman's having undergone contraceptive sterilization was increasing over time in Brazil and Peru, suggesting that the potential for future growth of this method remains strong. A consistent pattern of increased probability of sterilization with higher education was seen across all countries, seemingly dispelling certain controversial claims that the procedure may have been disproportionately performed on the poor. At the same time, the multilevel analytical approach pointed to significant cluster-level random effects, suggesting that there were additional unmeasured contextual influences on women's propensity to choose sterilization.     

Oligonucleotide circularization by template-directed chemical ligation.

An efficient method for producing the covalent closure of oligonucleotides on complementary templates by the action of BrCN was developed. A rational design of linear precursor oligonucleotides was studied, and the effect of factors such as oligonucleotide concentration and oligomer-template length ratio was evaluated. The efficiency of circularization was shown to correlate well with the secondary structure of the precursor oligomer (as predicted by a simple computer analysis), hairpin-like structures bearing free termini clearly favouring the circularization reaction. A novel idea, consisting of the incorporation of non-nucleotide insertions in the precursor oligomer (namely, 1,2-dideoxy-D-ribofuranose residues), may render this method universal and highly effective. An original set of assays was developed to confirm the circular structure of the covalently closed oligonucleotides.     

Proceedings: Female sterilization: long-term follow-up with particular reference to regret

220 women who had been sterilized 20-46 months previously were questioned about any regrets they felt about the operation. 13 patients expressed regret (5.9%) and 15 expressed uncertainty (6.8%). The worsening of the sex life, the occurrence of menorrhagia, dysmenorrhea, or both, and nervous problems were each significantly associated with the regret/uncertain group (p less than .01). 7 patients also experienced weight gain and 3 reported a bad conscience. The percentage of sterilization patients expressing regret is felt likely to decline since smaller families are now favored. The results did not indicate that sterilization necessarily causes the problem.     

Decontamination of laboratory microbiological waste by steam sterilization.

A steam sterilizer (autoclave) was tested to determine the operating parameters that affected sterilization of microbiological waste. Tests involved standardized loads (5, 10 ad 15 lb [ca. 2.27, 4.54, and 6.80 kg, respectively]) contaminated petri plates in autoclave bags placed in polypropylene or stainless steel containers. Thermal and biological data were obtained by using a digital potentiometer and a biological indicator containing spores of Bacillus stearothermophilus, respectively. The transfer of heat was more efficient when smaller loads of microbiological waste were tested and stainless steel rather than polypropylene containers were used. A single bag with the sides rolled down to expose the top layer of petri plates allowed heat to pass better than did a single bag with the top constricted by a twist-tie. The presence of water in the autoclave bag did not significantly improve heat-up time in stainless steel or polypropylene containers. The results of biological tests substantiated the temperature data. When 10 or 15 lb of microbiological waste was exposed to various test conditions, the only condition that ensured the destruction of B. stearothermophilus involved the use of a stainless steel container (with or without water) for 90 min. Autoclaving for 45 min resulted in the destruction of bacteria included in 10 lb (136 +/- 3 plates) or 15 lb (205 +/- 6 plates) of microbiological waste when stainless steel containers with or without water or polypropylene containers with water used, whereas 60 min was required to kill all bacteria if polypropylene containers without water were used.     

Site-directed modification of DNA duplexes by chemical ligation.

The efficiency of chemical ligation method have been demonstrated by assembling a number of DNA duplexes with modified sugar phosphate backbone. Condensation on a tetradecanucleotide template of hexa(penta)- and undecanucleotides differing only in the terminal nucleoside residue have been performed using water-soluble carbodiimide as a condensing agent. As was shown by comparing the efficiency of chemical ligation of single-strand breaks in those duplexes, the reaction rate rises 70 or 45 times if the 3'-OH group is substituted with an amino or phosphate group (the yield of products with a phosphoramidate or pyrophosphate bond is 96-100% in 6 d). Changes in the conformation of reacting groups caused by mismatched base pairs (A.A, A.C) as well as the hybrid rU.dA pair or an unpaired base make the template-directed condensation less effective. The thermal stability of DNA duplexes was assayed before and after the chemical ligation. Among all of the modified duplexes, only the duplex containing 3'-rU in the nick was found to be a substrate of T4 DNA ligase.     

Effects of ligation on ethanol-induced Balbiani ring puffing in salivary glands of Chironomus

Treatment of Chironomus larvae with dilute (0.5%–1.0%) ethanol results in puffing changes similar to those obtained with galactose in the Balbiani rings (BRs) of the salivary gland chromosomes. A shift in the relative size of BR1 and BR2 in chromosome 4 of C. pallidivittatus or C. tentans was observed within 1–2 days after ethanol treatment. The exceptional Balbiani ring, BR6 in chromosome 3, began to appear within 1 day after ethanol treatment of C. pallidivittatus and was fully developed after 3–4 days. Prepupae appeared to be refractory to the treatment. To localize possible controls of BR puffing in Chironomus, ligatures were made at various positions along the thorax and the anterior abdominal segments of the ethanoltreated larvae. In surviving larvae, ligated anterior to the brain or posterior to the salivary glands, induction of BR6 could be detected. In contrast, little or no BR6 puff induction was found in animals ligated in the middle of the second segment approximately between the brain and the salivary glands. No shift in the BR1/BR2 relation occurred with any of the ligations combined with ethanol treatment.