Progress in reducing the pale, soft and exudative (PSE) problem in pork and poultry meat.

Research in the area of the pale, soft and exudative (PSE) pork and poultry meat is reviewed in this article with an emphasis on genetic, biochemical and metabolic factors contributing to the problem. Over the past five decades, there has been much more work in the pork meat area where a few genetic markers have been identified, and are currently used to remove susceptible animals from the herd. Some of the markers are linked to aberrant calcium regulation in the early postmortem muscle. The poultry industry is still not at the point of using genetic marker(s); however, some recent work has revealed several potential markers. The review also discusses environmental factors such as antemortem stress and early postmortem processing practices (e.g. chilling rate) that can influence the development and severity of the PSE phenomenon. Some of these factors are known to cause protein denaturation at the early stage of postmortem and directly contribute to poor water-holding capacity and inferior texture in fresh meat and later in processed products. A newer hypothesis suggesting that variation in protein oxidation, in response to antemortem stress and early postmortem tissue environment, can contribute to development of PSE pork is also discussed. Finally, a few recommendations for future work are proposed.

Sterilization.

Sterilization is accepted as a permanent method of contraception by many couples in the world. Female sterilization is more widely used than male sterilization, but the latter is used by many couples in developed countries. The most widely used methods for female sterilization are simple tubal ligation, electrocautery of the fallopian tubes, and occlusion of the tubes by Hulka or Filshie clips or Falope rings. These procedures may be carried out either by minilaparotomy or by laparoscopy, under local anaesthesia. Sterilization may be performed immediately following pregnancy, or as an interval operation. The effectiveness of female sterilization is high, with failure rates of about 1-2 per 1000 procedures. Immediate complications are few and minor, while there appear to be no serious, long-term adverse effects. It is possible that there is a protective effect against ovarian cancer. Potential new technologies for female sterilization include the use of chemicals, such as quinacrine, for transcervical tubal occlusion, and hysteroscopic methods. Male sterilization is more simple and can readily be performed under local anaesthesia. A new technique originating in China, the no-scalpel technique, has made the procedure even more simple and produces fewer complications such as haematoma. It is possible that the direct injection of plug-forming material into the vas may render the procedure more reversible. Concerns about possible adverse effects of vasectomy on cardiovascular diseases and testicular cancer largely have been dispelled, but a possible weak association between vasectomy and prostatic cancer continues to be studied.

PIP: At present, the most widely used methods for female sterilization are simple tubal ligation, electrocautery of the fallopian tubes, and occlusion of the tubes by Hulka or Filshie clips or Falope rings. Potential new technologies include hysteroscopic methods and the use of chemicals such as quinacrine for transcervical tubal occlusion. Even more technical advances have occurred with male sterilization and concerns about a link to cardiovascular diseases and testicular cancer have been largely dispelled. The no-scalpel technique, originated in China, has made male sterilization simpler and free from complications such as hematoma. Direct injection of plug-forming material into the vas may increase the possibility of male sterilization reversal. Reviewed in this article is the clinical research on the effectiveness, long-term effects, reversibility, and surgical approaches of current and potential methods of sexual sterilization.

The evolution of methods for female sterilization.

Methods for the sterilization of women by occlusion of the Fallopian tubes have evolved by changes in the approaches to the tubes and trials of various methods for occluding the tubal lumen. Approaches to the tube have included: the anterior abdominal wall routes by laparotomy, minilaparotomy and laparoscopy; a vaginal approach through the posterior vaginal fornix; and transcervical approaches, either blind, or via the hysteroscope. Methods for obtaining tubal occlusion have included: excision and suture techniques; electrocautery; clips and rings; intratubal occlusive devices and chemicals introduced into the tubal lumen. The development of each of the approaches to the tube and of the methods for obtaining tubal occlusion are discussed.

The development of new technologies for female sterilization: conclusions and recommendations for research.

The conclusions and recommendations for research made during the consultation on the development of new technologies for female sterilization are presented. The participants in the consultation agreed that there was no single new method of female sterilization ready for introduction into service programs, but that there were several approaches with the potential to improve existing methods, or to provide new methods for tubal occlusion. A number of areas for future research were recommended including: additional operational research on existing abdominal approaches to tubal occlusion; further research into the physiology and pharmacology of the Fallopian tube; chemical occlusion using a transcervical approach with balloon pumps; techniques for endometrial ablation as sterilization methods; transcervical Fallopian tube cannulation; the use of quinacrine and other chemicals, such as elemental iodine, as tubal sclerosants, provided that these substances meet modern toxicological requirements.

The evolution of methods for female sterilization.

Methods for the sterilization of women by occlusion of the Fallopian tubes have evolved by changes in the approaches to the tubes and trials of various methods for occluding the tubal lumen. Approaches to the tube have included: the anterior abdominal wall routes by laparotomy, minilaparotomy and laparoscopy; a vaginal approach through the posterior vaginal fornix; and transcervical approaches, either blind, or via the hysteroscope. Methods for obtaining tubal occlusion have included: excision and suture techniques; electrocautery; clips and rings; intratubal occlusive devices and chemicals introduced into the tubal lumen. The development of each of the approaches to the tube and of the methods for obtaining tubal occlusion are discussed.

Cord blood lymphocyte subpopulations and mitogenic activity in whole blood microculture.

Comparative studies on cord and adult blood showed that cord blood contained at least twice as many lymphocytes as adult blood. Relatively, the percentage of T cells (E-RFC) was significantly lower in cord blood lymphocytes. The percentage of B cells (EAC-RFC and SmIg bearing cells), as well as the total number of T and B cells (mm(-3)), was significantly higher in cord blood. In vitro mitogen transformation of cord and adult lymphocytes in while blood, cultured for different times and diluted to contain equivalent numbers of lymphocytes per culture, showed significant qualitative and quantitative differences. Responses to the T cell mitogens phytohaemagglutinin (PHA) and concanavalin A (Con A) were examined from 3 to 6 days in culture. Cord blood lymphocytes were significantly more responsive when cultured for 3 to 4 days, similar to adult cells after 5 days, but significantly less responsive after 6 days in culture. The optimal levels of T cell mitogen responsiveness in cord cells (Day 4) were similar to adut cells (Day 6). Spontaneous transformation of unstimulated lymphocytes and B cell mitogen transformation with pokeweed mitogen (PWM) and staphylococcal protein A (SpA) were all significantly higher in cord blood than in adult whole blood cultured for 5 days.

Some properties of human endometrial alkaline phosphatase.

A study of some biochemical properties of alkaline phosphatase derived from human endometrium has been undertaken. The endometrial enzyme has been shown to be different from alkaline phosphatases obtained from placenta and small intestine. Endometrial alkaline phosphatase is inhibited by sodium deoxycholate but not by L-phenylalanine; it is completely inhibited by 3 M urea. Magnesium ions have no significant effect on the endometrial enzyme. No differences in biochemical properties were observed when alkaline phosphatase from follicular phase endometrium was compared with that from luteal phase tissue. Acrylamide gel electrophoresis showed a single, constant band of enzyme at all stages of the cycle. It is concluded that, despite the cyclic appearance of alkaline phosphatase in endometrial glands and the constant presence of the enzyme in blood vessels, there is but one variety of alkaline phosphatase in human endometrium.