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Failure to obtain desired postpartum sterilization: risk and predictors.

OBJECTIVE: The aim of this study was to assess the rate of and risk factors for not obtaining postpartum sterilization among women who expressed a desire for sterilization during antepartum care. METHODS: In this retrospective study, we identified a cohort of women who expressed desire for postpartum sterilization at our center between March 2002 and November 2003. We compared women who did and those who did not undergo the procedure, based on demographic, antenatal, and intrapartum factors. RESULTS: Of the 712 women who expressed desire for postpartum sterilization during antepartum care, 327 (46%) did not undergo the procedure. In multivariable analysis, women who were between the ages of 21 and 25 years (adjusted odds ratio [OR] 0.56, 95% confidence interval [CI] 0.35-0.89), were African American (OR 0.68, 95% CI 0.47-1.00), requested sterilization in the second trimester (OR 0.50, 95% CI 0.29-0.86)), and had a vaginal delivery (OR 0.21, 95% CI 0.14-0.32) rather than cesarean delivery were least likely to undergo postpartum sterilization. CONCLUSION: Despite their initial request, only 54% of women in our sample underwent sterilization. Young age, African-American race, request in the second trimester, and vaginal delivery were significantly associated with not undergoing sterilization. Our data suggest that providers should counsel all women who desire postpartum sterilization about the wide array of contraceptive methods available, with the understanding that approximately half of all women may not undergo the sterilization procedure. LEVEL OF EVIDENCE: II-2.

Adult↗

Influence of sterilization on mechanical properties and fatigue resistance of nickel-titanium rotary endodontic instruments.

AIM: To evaluate the effect of repeated sterilization cycles in dry oven or autoclave, on the mechanical behaviour and fatigue resistance of rotary endodontic Ni-Ti instruments. METHODOLOGY: New Ni-Ti instruments were subjected to five consecutive sterilization cycles in a dry oven or steam autoclave. Microhardness was measured in the nonmachined parts of the shanks of instruments using a Vickers indenter. Specimens of Ni-Ti wires were submitted to the same sterilization protocol and tensile tested until rupture. A group of instruments were fatigued to one half of their average fatigue life and then sterilized. New and sterilized instruments were fatigue tested until rupture. anova tests at alpha = 0.05 were used for statistical analysis. RESULTS: Sterilization procedures resulted in no significant changes in Vickers microhardness, nor in the parameters describing the mechanical behaviour of the wires. However, the number of cycles to failure was statistically higher for all instruments after dry heat or autoclave sterilization cycles. In the instruments previously fatigued to one half of their fatigue life, autoclave sterilization gave rise to an increase of 39% in the remaining number of cycles to failure. CONCLUSIONS: Changes in the mechanical properties of Ni-Ti endodontic instruments after five cycles of commonly used sterilization procedures were insignificant. The sterilization procedures are safe as they produced a significant increase in the fatigue resistance of the instruments.

Analysis of Variance↗

Do women's attitudes towards abortion and contraceptive methods influence their option for sterilization?

This paper analyzes the attitudes of low-income women towards abortion and contraception. A survey was conducted in 1992 with a total of 3,149 childbearing-age women living on the outskirts of the Greater Metropolitan São Paulo Area. The study focuses on a sub-sample of 583 women. Attitudes of sterilized and non-sterilized women are compared. Women, especially those sterilized, found the most important attribute of a contraceptive method to be its effectiveness. Women currently taking the pill were less likely than those sterilized to agree that sterilization was the best method because of its effectiveness. Sterilized women were less likely than non-sterilized women to trust the pill. Sterilized women were more likely than non-sterilized to have reported adverse effects from the pill. Most women found abortion unacceptable except in the case of risk to the woman's life. Women using more effective methods showed stronger negative attitudes towards abortion. The tendency to be sterilized while still young was associated with more negative attitudes towards abortion. Family planning activities in basic health care services should include individual counseling for contraceptive use.

Abortion, Legal↗

Effect of sterilization method and other modifications on the wear resistance of acetabular cups made of ultra-high molecular weight polyethylene. A hip-simulator study.

BACKGROUND: Wear of ultra-high molecular weight polyethylene acetabular cups in hip prostheses produces billions of submicrometer wear particles annually that can cause osteolysis and loosening of the components. Thus, substantial improvement of the wear resistance of ultra-high molecular weight polyethylene could extend the clinical life span of total hip prostheses. It has become apparent that the conditions under which ultra-high molecular weight polyethylene cups have been sterilized can markedly affect their long-term wear properties, and new sterilization methods and other modifications have been developed to minimize the negative effects. METHODS: In the present study, a hip-joint simulator was used to assess whether it is preferable to sterilize ultra-high molecular weight polyethylene cups without gamma irradiation, to avoid radiation-induced oxidative degradation, or to sterilize with gamma irradiation while the cups are packaged in a suitable low-oxygen atmosphere to minimize oxidation while retaining the increased wear resistance conferred by the radiation-induced cross-linking. Ion-implanted cups and cups made of a highly crystalline polyethylene (Hylamer) also were investigated. Cups made of each material were subjected to wear-testing prior to and after artificial thermal aging to accelerate oxidative degradation. RESULTS: The results of the present study demonstrated that the cross-linking induced by gamma irradiation improves the wear resistance of ultra-high molecular weight polyethylene, while oxidation reduces it. Without thermal aging, the two types of cups that were sterilized with gamma irradiation while in low-oxygen packaging exhibited about a 50 percent lower rate of wear than did either the nonsterilized cups or the nonirradiated cups sterilized with gas plasma. There was a comparable advantage in the rate of wear after fourteen days of thermal aging. However, after thirty days of aging, the cups sterilized with gamma irradiation in low-oxygen packaging wore several times faster than did the nonirradiated cups. Ion-implanting improved the wear resistance without thermal aging, but after extensive thermal aging the oxidation and wear were greater than those of the controls. Hylamer cups (that is, those that were sterilized with gas plasma) exhibited wear properties very close to those of the nonsterilized ultra-high molecular weight polyethylene cups (the controls) with or without aging. CONCLUSIONS: Sterilizing an ultra-high molecular weight polyethylene acetabular cup without radiation (for example, with ethylene oxide or gas plasma) avoids immediate and long-term oxidative degradation of the implant but does not improve the inherent wear resistance of the polyethylene. Sterilizing with use of gamma irradiation with the implant packaged in a low-oxygen atmosphere avoids immediate oxidation and cross-links the polyethylene, thereby increasing its wear resistance, but long-term oxidation of the residual free radicals may markedly reduce the wear resistance. Ideally, cross-linking with gamma irradiation to reduce wear should be done in a manner that avoids both immediate and long-term oxidation.

Acetabulum↗

[Attitudes of women and gynecologists towards voluntary sterilization in Serbia?].

INTRODUCTION: Voluntary sterilization is a very effective and safe birth control method. Is it, however, accepted as a birth control method in Serbia? This is certainly a question that should be explored, regardless of the fact that voluntary sterilization is neither accessible nor promoted. MATERIAL AND METHODS: The target group included women who decided to terminate their pregnancy, and gynecologists from various parts of Serbia. RESULTS AND DISCUSSION: The survey results indicate that more than half of women believe that voluntary sterilization should be available in Serbia. Also, a large number of surveyed women, almost half of them, would undergo voluntary sterilization. Younger women, respondents with secondary education, those who gave birth to a desired number of children, as well as those who have a good relationship with their partners, those who have experienced a great number of induced abortions, namely those who wish to use contraception in the future, are more open to voluntary sterilization. The majority of gynecologists also think that voluntary sterilization should become available in Serbia. Most of them consider therapeutic and eugenic reasons as appropriate for surgical sterilization. However, gynecologists lack current knowledge about this contraceptive method, and would not accept to use voluntary sterilization themselves. CONCLUSION: The reasons for individual nonacceptance indicate that many of the registered ambivalent or negative opinions can be changed by spreading knowledge on voluntary sterilization. Moreover, the knowledge of gynecologists about voluntary sterilization should be improved as well.

Adult↗

Sterilization efficiency of the photocatalyst against environmental microorganisms in a health care facility.

The photocatalyst equipment consists of a titanium dioxide membrane and an ultraviolet lamp. The authors studied if the photocatalyst equipment is practically useful in sterilizing environmental microorganisms in the health care facility. The number of microorganisms was compared in the cases of no sterilization (control) and the photocatalyst sterilization. As a result, a statistical difference was observed between control and the photocatalyst sterilization against airborne microorganisms (p < 0.01), but not against surface microorganisms (p > 0.2). The photocatalyst uses an air sucking system, so it may be ineffective against microorganisms tightly attached to surfaces. However, the effectiveness of the photocatalyst to sterilize airborne microorganisms in the health care facility was successfully confirmed. Concerning the humidity effect on the photocatalyst sterilization, the authors compared the number of airborne microorganisms in cases of the control, UV alone and photocatalyst sterilization when humidity was changed. A statistical difference was observed between UV and the photocatalyst sterilization (p < 0.01) when humidity was increased to 60-70%, but not observed between UV and the photocatalyst sterilization (p > 0.2) when humidity was not controlled and was around 10-20%. This indicates that maintaining high humidity levels will present satisfactory sterilization results due to a greater production of OH radicals. From data obtained, no effect of the adsorption on the TiO2 membrane could be observed.

Adsorption↗

[Quality of the sterilization process in the dental practice].

A survey was performed among 249 Dutch dentists on the use and functioning of sterilizers in their practice and on the quality control of the sterilization process. 99% of the dentists use a sterilizer. Only 1% uses only a thermodesinfector. 7.3% of the sterilizers tested did not function properly, based on a microbiological test. 76% of the sterilizers are not serviced on a regular basis. These sterilizers show more often failures in the sterilization process. It is concluded that although over 92% of the sterilizers in Dutch dental offices do function well, improvement on the quality control of the sterilization process is feasible and necessary. Besides an annual service, a regular control of the sterilization process itself, e.g. by using biological indicators, in combination with physical and/or chemical monitoring, is one of het methods to achieve this.

Data Collection↗

National survey of quality assurance activities for pharmacy-prepared sterile products in hospitals.

The results of a survey of pharmacy department activities for quality assurance in the preparation of sterile drug products in short-term, nonfederal hospitals are reported. A questionnaire was mailed in March and April 1991 to pharmacy directors at hospitals that had indicated in ASHP's 1990 national survey of pharmaceutical services that they had formal quality assurance processes for intravenous admixture preparation. The adjusted gross sample size was 465. The net response rate was 71% (330 usable replies). Nearly all respondents indicated that sterile drug products were prepared extemporaneously in their departments; 61% reported batch preparation of such products. Both pharmacists and pharmacy technicians prepared sterile products. Respondents identified which guidelines were used in developing departmental policies and procedures for sterile product preparation. Specific areas were identified in which educational programs for pharmacists are needed; the most frequently indicated area (85%) was principles of aseptic technique. A majority of respondents used the following means for the orientation and training of personnel who prepare sterile products: aseptic technique lectures or videotapes, on-the-job training, written policies and procedures, and direct observation of technique. Almost all of the respondents (99%) had laminar-airflow hoods in their departments. Three fourths of those respondents indicated that laminar-airflow hoods were located in a limited-access room. Half of the respondents reported that laminar-airflow hoods were located certified every six months and that prefilters were changed monthly. Less than one third sampled environmental areas for microbial contamination. Less than one third of the surveyed hospitals routinely sampled sterile products for microbial contamination or pyrogens. Almost half indicated the absence of policies and procedures for testing chemical purity, drug concentration, sterility, pyrogenicity, or the environment for sterile preparations. Few respondents indicated the use of sterilization techniques other than microbial filtration, which was used by 32% of pharmacies involved in extemporaneous preparation and 16% of those involved in batch preparation. About 90% of the respondents used published references and manufacturers' recommendations to determine expiration dating. This survey revealed that certain quality assurance procedures related to pharmacy-prepared sterile products need major improvement.

Drug Compounding↗

[Optimal terms for sterilization].

Sterilization can be performed in the immediate postpartum, post abortion, or as an interval procedure. Traditionally, postpartum sterilization should be performed within the first two days after delivery, thereafter the risk for infection is believed to increase. Sterilization and artificial abortion are performed as concomitant procedures, while interval sterilization is carried out at least six weeks after the termination of pregnancy. Though many authors consider the sterilization in the immediate postpartum and postabortion period safe enough, the comparative studies show that interval sterilization has less complications. Postpartum (postabortion) sterilization has much more disadvantages than advantages in comparison to interval sterilization. The main advantage of postpartum sterilization is only one hospitalization while disadvantages are the increased risk of hemorrhage, uterine perforation, thromboembolic disease, infection, technical difficulties, and psychological problems. For these reasons interval sterilization is recommended.

Abortion, Induced↗

Formaldehyde, sodium hypochlorite, and metabisulphite are equally effective as sterilants for central delivery systems.

Sterilants are used to disinfect reverse osmosis (RO) thin film composite membranes or peripheral loop water delivery systems. Formaldehyde (4.0% weight/volume) and metabisulphite (1.0%) were used to sterilize the RO and peripheral loop, and sodium hypochlorite (0.5%) was used to sterilize the peripheral loop with only acid/alkaline treatment of the RO; each sterilant was evaluated for 4 months. Sanitization at the machine was with sodium hypochlorite or glutaraldehyde. Quantitative RO processed water (weekly) and dialysate (4-6 from each station during the period of each sterilant) cultures were obtained. AAMI standards were used (< 200 CFU/ml RO water; < 2,000 CFU/ml dialysate). Bacterial growth exceeded Association for the Advancement of Medical Instrumentation (AAMI) limits in 16% of RO water and 4.7% of dialysate samples, but repeat cultures invariably failed to confirm initial abnormal results. Chi-square analysis showed no differences among sterilants. No difference among sterilants was noted in arithmetic or log10 mean colony counts. Sporadic low level gram positive and gram negative organism growth occurred with all sterilants. Continued "sterility" that met AAMI standards was obtained for 1 year, first with metabisulphite and then with acid/alkaline RO and sodium hypochlorite loop treatment. It is concluded that all three sterilants are effective for disinfection of hemodialysis delivery systems. Sodium hypochlorite is recommended because of its safety advantages and readily available test of adequate removal.

Colony Count, Microbial↗

Effectiveness of three types of sterilization on the contents of sharps containers.

The purpose of this study was to test the effect of treatment in a gravity steam autoclave, high-vacuum steam autoclave, or an unsaturated chemical vapor sterilizer on endospores present on strips or placed inside of dental anesthetic cartridges held within sharps containers. Strips with 1.7 X 10(5) Bacillus stearothermophilus endospores were used; the cartridges were soiled with an equal number of spores or spores mixed with blood. If sterilization was not accomplished after the initial period, additional exposure time was added. Neither the presence of blood or anesthetic solution nor the position of the container affected the efficiency of sterilization. Soiled cartridges were much more difficult than strips to sterilize. Intact cartridges could not be sterilized by two runs in a gravity steam autoclave or an unsaturated chemical vapor sterilizer or one run in a high-vacuum steam autoclave. Sterilization occurred after two runs in the gravity steam autoclave and unsaturated chemical vapor sterilizer only when one end of the cartridge was removed prior to processing. Results indicated that unopened spore-soiled cartridges are not readily sterilized by commonplace office sterilizers, even after extended exposure.

Anesthesia, Dental↗

[Survey of methods of cleaning, decontamination, disinfection and sterilization in dental health services in tropical areas].

The International Aid for Ontology (IAO) carried out this survey of hygiene in the dental health services of 5 French-speaking African countries in 1994, in association with the Faculty of Pharmaceutical and Biological Sciences of Paris. This study received support from the World Health Organization (WHO), the French Ministry for Cooperation and the European Community and the Ivory Coast Oral and Dental Hygiene and Health Committee (CIHSBD). Twenty-nine dental services from Benin (3), Burkina Faso (6), Ivory Coast (12), Mali (5), Niger (3) participated in this survey which gives an insight into the daily hygiene routines of these services. The cleaning, decontamination, disinfection and sterilization procedures for premises, dental equipment, instruments, hands and disposable items were investigated. No individual protocols are reported. Bench tops were cleaned or disinfected daily in 73% of centers and floors were cleaned or disinfected daily in 59% of centers. Walls were cleaned once per week in 44% of the centers. Hands were always washed between patients, with 68% of dental surgeons using only solid or liquid cleansing soaps and the others using antiseptic or disinfectant solutions. The dentist's chair was cleaned or disinfected daily in 68% of centers, mostly with soap (43%) or diluted bleach (23%). Vacuum equipment was cleaned with soap (50%) or diluted bleach (57%), with some surgeries using a combination of the two. Hand pieces and turbines were cleaned and disinfected after each use with alcohol (35%) or diluted bleach (26%) and were sterilized in 9% of centers. Instruments were sterilized with a Poupinel (63%), unspecified sterilizer (26%), autoclave (7%) or low temperature disinfection procedure (4%). Instruments were regularly sterilized in all centers. Single-use disposable items were often reused: 88% of centers reused gloves, 64% anesthetic cartridges and 32% disposable needles. This survey demonstrates that dentists do attempt to achieve appropriate hygiene standards despite difficult practice conditions, exacerbated by supply problems. In all applications, hygiene involves a succession of closely-related, logical steps, which form an asepsis chain aimed at preventing the transmission of infection. Our survey shows that fundamental elements of hygiene require attention to achieve this aim. The cleaning, disinfection and sterilizing of floor surfaces and equipment should be improved and more widespread use made of disposable items. It is important to define the hygiene level required for particular treatments, taking into account the oral and dental micro flora and whether the equipment has been decontaminated, disinfected or sterilized. A piece of equipment is decontaminated if it has been mechanically cleaned and decontaminated. It is disinfected if these steps are followed by rinsing with sterile water, drying and conditioning. An item is described as sterilized if it is cleaned, decontaminated, rinsed, dried, conditioned and then sterilized. We found that a wide variety of chemicals were used to clean hands, surfaces and equipment. The nature and appropriate methods of use of these chemicals were not widely known. Understanding the chemical composition of these chemicals makes it possible to classify them into cleaning agents, detergents, decontaminating agents and disinfectants. The definition, choice and use of antiseptics and disinfectants should be strictly controlled. It is also vital that single-use disposable items are used only once and are never reused. Hygiene in the dental surgery is a chain of processes aimed at protecting the patient and the medical staff. There are many links in the chain, involving floor and surface hygiene, hand washing by dentists and dental assistants, washing of surgery linen and treatment of equipment. Dental practitioners should continually focus on ensuring that the chain of hygiene procedures is not broken, in their own interests as well as in those of their patients.

Benin↗

Sterilization. Determining a good candidate.

After 4 years, 10% of the 1800 low-income women in a 5-year study felt some regrets after the procedure. Although each individual is different, if a woman has 1 or more of the following characteristics, she may not be a good candidate for sterilization: under age 30; has few or no children; not involved in a stable relationship; made the decision to be sterilized alone and with minimal reflection; recently experienced a personal life crisis; feels sterilization will solve a sexual problem; expectations about sterilization are unrealistic; pressured by others to be sterilized. Although women who have had the procedure sometimes experience regret, other women regret not having been sterilized. Approximately 40% of the women who decided for sterilization but had their intentions blocked expressed regret at the short-term follow-up, and one-third reported regret at the second interview 4 years later. Also, women who chose not to be sterilized and then experienced a subsequent pregnancy were 7 times more likely to express regret than women who went through with the procedure. To counsel a woman who wants no more children but does not want sterilization, ask her how she would feel if she became pregnant again, and try to determine how badly she does not want to be pregnant, says Libby Antarsh, PhD, director of US programs for the Association of Voluntary Surgical Contraception in New York City. Also, make sure she has accurate information about other methods of birth control, she says.

Ambulatory Care Facilities↗

Hormonal and menstrual changes after laparoscopic sterilization by Falope-rings or Filshie-clips.

OBJECTIVE: To evaluate the influence of laparoscopic sterilization by Falope-rings (Cabot Medical Corp., Langhorne, PA) or Filshie-clips (Femcare, Nottingham, United Kingdom) on menstrual pattern and ovulatory function. DESIGN: A prospective, nonrandomized study of women sterilized by Falope-rings (n = 6) or Filshie-clips (n = 5). Menstrual charts were kept. Serum follicle-stimulating hormone (FSH), estradiol (E2) and progesterone (P) were measured by means of radioimmunoassay in one cycle before and 3, 6, and 12 months after the sterilization. Blood samples were drawn on day -6, -2, 0, +6, +10 of the menstrual cycle, ovulation corresponding to day 0. The women sterilized by Filshie-clips had abdominal ultrasonography of the ovaries measuring the leading follicle on day -6, -2, 0, +6 of the menstrual cycle. PATIENTS: Twelve women, 25 to 38 years old, with regular menstrual cycles and no use of oral contraceptives or intrauterine contraceptive device at least 6 months before sterilization. One woman was excluded. RESULTS: After the sterilization, all women reported unchanged menstrual pattern. The follicular rise in E2 unchanged, and FSH levels fell accordingly. Progesterone levels were ovulatory, but the midluteal P peak 3 months poststerilization was significantly decreased. Serial abdominal ultrasonography in women sterilized by Filshie-clips confirmed ovulation in all cycles except in one woman, who had an unruptured follicle in one cycle before and in the sixth cycle after sterilization. CONCLUSION: Laparoscopic sterilization by Falope-rings or Filshie-clips does not seem to interfere with menstrual pattern or ovulatory function.

Adult↗

Sterilization-in-place of concentrated nutrient solutions

Sterilization-in-place (batch sterilization) behavior of concentrated nutrient solutions was quantified for various nutrient solutions of fermentation processing interest. Experimental observations of sterilization temperatures and corresponding pressures suggested that sterilization pressures were substantially lower for concentrated nutrient solutions than for water. This effect was believed to be directly related to the lower vapor pressure and lower activity coefficient of these concentrated nutrient solutions. Using thermodynamic data for the specific nutrient, pressures and temperatures, calculated as a function of nutrient concentration, compared favorably with observed values. This method permits estimation of the expected sterilization pressure for concentrated nutrients for which no experimental observations have yet been made at the sterilization temperature of interest. Estimate accuracy, ranging from 0.006 to 0.06 bar, can be enhanced if one set of experimental temperature/pressure values is known at the expected sterilization scale. The potential impact of the nature of concentrated nutrient solutions on steam-in-place vessel headspace temperature distributions, D-values of B. stearothermophilus, and overall sterilization effectiveness is also discussed. The low vapor pressure of concentrated nutrient solutions was hypothesized to directly impact air removal effectiveness and sterilization performance during batch sterilization. Copyright 1999 John Wiley & Sons, Inc.

Journal Article↗

Genetic analysis of X-linked hybrid sterility in the house mouse.

Hybrid sterility is a common postzygotic reproductive isolation mechanism that appears in the early stages of speciation of various organisms. Mus musculus musculus and Mus musculus domesticus represent two recently separated mouse subspecies particularly suitable for genetic studies of hybrid sterility. Here we show that the introgression of Chr X of M. m. musculus origin (PWD/Ph inbred strain, henceforth PWD) into the genetic background of the C57BL/6J (henceforth B6) inbred strain (predominantly of M. m. domesticus origin) causes male sterility. The X-linked hybrid sterility is associated with reduced testes weight, lower sperm count, and morphological abnormalities of sperm heads. The analysis of recombinant Chr Xs in sterile and fertile males as well as quantitative trait locus (QTL) analysis of several fertility parameters revealed an oligogenic nature of the X-linked hybrid sterility. The Hstx1 locus responsible for male sterility was mapped near DXMit119 in the central part of Chr X. To ensure full sterility, the PWD allele of Hstx1 has to be supported with the PWD allelic form of loci in at least one proximal and/or one distal region of Chr X. Mapping and cloning of Hstx1 and other genes responsible for sterility of B6-X PWD Y B6 males could help to elucidate the special role of Chr X in hybrid sterility and consequently in speciation.

Acrosome Reaction↗

The cellular basis for interaction of sterility factors in the mouse t haplotype.

The t haplotypes are variant forms of the proximal one-third of chromosome 17 in the mouse. They contain four inversions (relative to the wildtype DNA) extending over most of this region and house a number of male sterility factors. Males carrying two complete t haplotypes (t/t) are sterile, as are males homozygous for S2, the sterility factor located in the most distal (relative to the centromere) inversion. Males homozygous for the sterility factor S1, located in the most proximal inversion, are not sterile; however, if such a male also is heterozygous for other sterility factors, then sterility results. It has been suggested therefore that homozygosity for S1 enhances the detrimental action of other sterility factors. Sperm from t/t males have severe motility defects and are unable to penetrate investment-free eggs, while sperm from fertile t/+ mice have less serious motility defects and exhibit a delay in penetration of investment-free eggs. To determine whether homozygosity for S1 enhances the cellular defects exhibited by sperm from mice heterozygous for other sterility factors, we compared the motility and egg-penetrating ability of sperm from fertile mice homozygous for S1 to that of sperm from mice carrying one complete t haplotype and one proximal or distal partial t haplotype. The data suggest that sperm from males carrying a proximal partial t haplotype and a complete t haplotype have serious defects in motility and penetration of the investment-free egg, and support the hypothesis that S1 enhances the detrimental effects of other sterility factors within the t haplotype.

Animals↗

The abundance of sterile transcripts in Giardia lamblia.

The protozoan parasite Giardia lamblia synthesizes a diverse and surprisingly abundant array of sterile transcripts unable to code for proteins. Random sampling of cDNAs from two evolutionarily divergent Giardia strains indicates that approximately 20% of cDNAs in the libraries represent polyadenylated sterile transcripts. RNase protection analysis and northern blot hybridization of three sterile transcript loci demonstrated that both the sterile transcript and a complementary mRNA were made in each case, further categorizing these sterile transcripts as antisense transcripts. Investigation of the genomic loci for these same three sterile antisense transcripts showed typical transcription units for the sense transcripts, but still failed to reveal a usable open reading frame for the sterile antisense transcripts. 5'-RACE mapped the transcription start site for one of the sterile antisense transcripts to an AT-rich region, as is typical for GIARDIA: It is unclear whether these sterile transcripts represent errors in transcription or whether they have regulatory functions within the cell, although preliminary investigations failed to reveal evidence for a role in developmental gene regulation. In either case, the presence of such a large pool of sterile antisense transcripts is dramatic evidence of the unusual molecular machinery of the early diverging protist G.lamblia.

Animals↗