Are donor-conceived people willing to use donors themselves? Insights from individuals conceived via donor-assisted reproduction.

STUDY QUESTION: Are donor-conceived people (DCP) willing to utilize donor gametes themselves if unable to conceive spontaneously? SUMMARY ANSWER: The majority of DCP would consider or are undecided about utilizing donor gametes and those who would consider the utilization are more likely to have been told about their donor-conceived origins at a young age by a family member and have overall positive experiences as a DCP. WHAT IS KNOWN ALREADY: DCP view their donor conception as an important part of their self-identity and many desire contact with genetically related individuals. Additionally, many believe that sperm donation should only be practiced if identifying information on the donor is provided. STUDY DESIGN, SIZE, DURATION: This was a cross-sectional study using a Web-based survey that was disseminated from 6 March to 15 August 2021. A total of 528 participants completed the questionnaire. PARTICIPANTS/MATERIALS, SETTING, METHODS: The researcher-created survey was sent to registered users of the Donor Sibling Registry (DSR) who were conceived via donor-assisted reproduction and were 18 years of age or older. The survey was optional and anonymous, and the main outcome measure was the willingness to use donated gametes if unable to spontaneously conceive. MAIN RESULTS AND THE ROLE OF CHANCE: Of the 528 participants who completed the survey, 40.2% (212/528) have or would consider using donor gametes themselves if unable to conceive spontaneously and 24.6% (130/528) were undecided. Those who had used or were undecided about the utilization were significantly younger (26 years vs. 31 years, P < 0.001) and less likely to be married (32.7% vs. 47.3%, P < 0.001) than those who would not consider using donor gametes. They were also less likely to self-identify as female (78.9% vs. 86.6%, P = 0.03) but had no difference in sexual orientation (P = 0.13). Additionally, they were more likely to have known about their donor-conceived origins for more years (18 (0-50) vs. 11 (0-61), P = 0.004), be informed by a family member (75.5% vs. 65.6%, P = 0.001) and have overall positive feelings about being conceived using a donor (93.0% vs. 52.5%, P < 0.001). LIMITATIONS, REASONS FOR CAUTION: A major limitation is that DSR participants may not be representative of all DCP. Additionally, analyzing the DCP who stated that they were undecided about using donor gametes into the 'would consider' group may be overestimating the openness to utilization in this group. WIDER IMPLICATIONS OF THE FINDINGS: The findings from this study give new insight for health care workers to further counsel patients who are considering using third-party reproduction by providing reassurance that the majority of their future children would consider similar means, if needed, to achieve their family-building goals. STUDY FUNDING/COMPETING INTEREST(S): Funding for this study was received from the Department of Obstetrics and Gynecology Division of Reproductive Endocrinology and Infertility, University of Colorado. All authors declare that there are no conflicts of interest to disclose. TRIAL REGISTRATION NUMBER: N/A.

Ultrasound markers for prediction of complex gastroschisis and adverse outcome: longitudinal prospective nationwide cohort study.

OBJECTIVES: To identify antenatal ultrasound markers that can differentiate between simple and complex gastroschisis and assess their predictive value. METHODS: This was a prospective nationwide study of pregnancies with isolated fetal gastroschisis that underwent serial longitudinal ultrasound examination at regular specified intervals between 20 and 37 weeks' gestation. The primary outcome was simple or complex (i.e. involving bowel atresia, volvulus, perforation or necrosis) gastroschisis at birth. Fetal biometry (abdominal circumference and estimated fetal weight), the occurrence of polyhydramnios, intra- and extra-abdominal bowel diameters and the pulsatility index (PI) of the superior mesenteric artery (SMA) were assessed. Linear mixed modeling was used to compare the individual trajectories of cases with simple and those with complex gastroschisis, and logistic regression analysis was used to estimate the strength of association between the ultrasound parameters and outcome. RESULTS: Of 104 pregnancies with isolated fetal gastroschisis included, four ended in intrauterine death. Eighty-one (81%) liveborn infants with simple and 19 (19%) with complex gastroschisis were included in the analysis. We found no relationship between fetal biometric variables and complex gastroschisis. The SMA-PI was significantly lower in fetuses with gastroschisis than in healthy controls, but did not differentiate between simple and complex gastroschisis. Both intra- and extra-abdominal bowel diameters were larger in cases with complex, compared to those with simple, gastroschisis (P < 0.001 and P < 0.005, respectively). The presence of intra-abdominal bowel diameter ≥ 97.7th percentile on at least three occasions, not necessarily on successive examinations, was associated with an increased risk of the fetus having complex gastroschisis (relative risk, 1.56 (95% CI, 1.02-2.10); P = 0.006; positive predictive value, 50.0%; negative predictive value, 81.4%). CONCLUSIONS: This large prospective longitudinal study found that intra-abdominal bowel dilatation when present repeatedly during fetal development can differentiate between simple and complex gastroschisis; however, the positive predictive value is low, and therefore the clinical usefulness of this marker is limited. © 2019 Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Triphenylsulfonium topophotochemistry.

The products from the 193 nm irradiation of triphenylsulfonium nonaflate (TPS) embedded in a poly(methyl methacrylate) (PMMA) film have been characterized. The analysis of the photoproduct formation was performed using chromatographic techniques including HPLC, GPC and GC-MS as well as UV-vis and NMR spectroscopic methods. Two previously unreported TPS photoproducts, triphenylene and dibenzothiophene, were detected; additionally, GPC and DOSY-NMR spectroscopic analyses after irradiation suggested that TPS fragments had been incorporated into the polymer film. The irradiation of acetonitrile solutions containing 10% w/v PMMA and 1% w/v TPS in a 1 cm-path-length cuvette showed only a trace amount of triphenylene or dibenzothiophene, indicating that topochemical factors were important for the formation of these molecules. The accumulated evidence indicates that both products were formed by in-cage, secondary photochemical reactions: 2-(phenylthio)biphenyl to triphenylene, and diphenylsulfide to dibenzothiophene.

Pancreatic ß-cell imaging in humans: fiction or option?

Diabetes mellitus is a growing worldwide epidemic disease, currently affecting 1 in 12 adults. Treatment of disease complications typically consumes ∼10% of healthcare budgets in developed societies. Whilst immune-mediated destruction of insulin-secreting pancreatic ß cells is responsible for Type 1 diabetes, both the loss and dysfunction of these cells underly the more prevalent Type 2 diabetes. The establishment of robust drug development programmes aimed at ß-cell restoration is still hampered by the absence of means to measure ß-cell mass prospectively in vivo, an approach which would provide new opportunities for understanding disease mechanisms and ultimately assigning personalized treatments. In the present review, we describe the progress towards this goal achieved by the Innovative Medicines Initiative in Diabetes, a collaborative public-private consortium supported by the European Commission and by dedicated resources of pharmaceutical companies. We compare several of the available imaging methods and molecular targets and provide suggestions as to the likeliest to lead to tractable approaches. Furthermore, we discuss the simultaneous development of animal models that can be used to measure subtle changes in ß-cell mass, a prerequisite for validating the clinical potential of the different imaging tracers.

Common distal elements orchestrate CIITA isoform-specific expression in multiple cell types.

Major histocompatibility class II (MHC-II) expression is critical for immune responses and is controlled by the MHC-II transactivator CIITA. CIITA is primarily regulated at the transcriptional level and is expressed from three main promoters with myeloid, lymphoid and interferon (IFN)-γ-treated non-hematopoietic cells using promoters pI, pIII and pIV, respectively. Recent studies in non-hematopoietic cells suggest that a series of distal regulatory elements may be involved in regulating CIITA transcription. To identify distal elements in B cells, a DNase I hypersensitivity screen was performed, revealing a series of potential novel regulatory elements. These elements were analyzed computationally and biochemically. Several regions displayed active histone modifications and/or enhanced expression of a reporter gene. Four of the elements interacted with pIII in B cells. These same four regions were also found to interact with pI in splenic dendritic cells (spDC). Intriguingly, examination of the above interactions in pI-knockout-derived spDC showed a switch to the next available promoter, pIII. Extensive DNA methylation was found at the pI region in B cells, suggesting that this promoter is not accessible in B cells. Thus, CIITA expression is likely mediated in hematopoietic cells by common elements with promoter accessibility having a part in promoter choice.

CIITA promoter I CARD-deficient mice express functional MHC class II genes in myeloid and lymphoid compartments.

Three distinct promoters control the master regulator of major histocompatibility complex (MHC) class II expression, class II transactivator (CIITA), in a cell type-specific manner. Promoter I (pI) CIITA, expressed primarily by dendritic cells (DCs) and macrophages, expresses a unique isoform that contains a caspase-recruitment domain (CARD). The activity and function of this isoform are not understood, but are believed to enhance the function of CIITA in antigen-presenting cells. To determine whether isoform I of CIITA has specific functions, CIITA mutant mice were created in which isoform I was replaced with isoform III sequences. Mice in which pI and the CARD-encoding exon were deleted were also created. No defect in the formation of CD4 T cells, the ability to respond to a model antigen or bacterial or viral challenge was observed in mice lacking CIITA isoform I. Although CIITA and MHC-II expression was decreased in splenic DCs, pI knockout animals expressed CIITA from downstream promoters, suggesting that control of pI activity is mediated by unknown distal elements that could act at pIII, the B-cell promoter. Thus, no critical function is linked to the CARD domain of CIITA isoform I with respect to basic immune system development, function and challenge.

Semen donors who are open to contact with their offspring: issues and implications for them and their families.

This study investigates the motivations, views and experiences of semen donors willing to have contact with their offspring. An online questionnaire for semen donors was posted by the US-based Donor Sibling Registry in 2009. A total of 164 respondents who had previously been donors completed the questionnaire, which consisted of 45 open and closed questions covering motivations for donating, health and medical information, experiences of donating, contact with offspring and implications of donating and contact for their families. The donors' primary motivation was to help other families, although payment was also a factor. Almost all donors were open to contact with their offspring and, where donors were partnered, three-quarters of the partners also supported possible contact. Almost one-third, however, had reservations about contact or were opposed. Two-thirds of donors' own children were interested in meeting the offspring. Contact between a donor and his offspring is often seen as a coming together of these two people only. The results of this study suggest that there are important ramifications for both of the families who become linked. Understanding gamete donation in this broader family context is crucial to the contribution that health professionals can make in this area.

Offspring searching for their sperm donors: how family type shapes the process.

BACKGROUND: This study examines the findings from the largest survey to date of donor-inseminated (DI) offspring and focuses on respondents' learning of the method of their conception and their desire to contact their donor. METHODS: Online questionnaires were completed by 741 DI offspring, of whom 61.8% have heterosexual parents and 38.2% have lesbian parents. Respondents were recruited via the Donor Sibling Registry, a non-profit US-based international registry that facilitates communication between donor-conceived offspring and their non-biological and biological relatives. Data were collected on family composition, offspring's feelings regarding the method of their conception, communication within families, donor anonymity and their search for their donors. This investigation focuses on the relationship between family type (single or dual-parent and lesbian or heterosexual parent/s) and offspring's reactions to learning of their DI conception. RESULTS: Offspring of lesbian parents learned of their DI origins at earlier ages than offspring of heterosexual parents. In the latter families, disclosure tended to occur earlier in single-parent than in dual-parent families. Disclosure was most likely to be confusing to offspring of heterosexual parents, particularly when it occurred at an older age. The vast majority of offspring in all types of families desired contact with their donor; however, comfort in expressing curiosity regarding one's donor was lowest in dual-parent heterosexual families, with about one-quarter reporting an inability to discuss their origins with their social father. CONCLUSIONS: Although the findings are not based on a random sample, the desire among offspring surveyed here is for greater openness and contact with their donor. A variety of strategies are needed for offspring of heterosexual couples to benefit optimally from the general trend toward openness in gamete donation.

Sperm and oocyte donors' experiences of anonymous donation and subsequent contact with their donor offspring.

BACKGROUND: This study examined the motivations and experiences of anonymous donors who decide to make themselves open to contact with their donor offspring. METHODS: Online questionnaires were completed by 63 sperm donors and 11 oocyte donors recruited via the Donor Sibling Registry (http://www.donorsiblingregistry.com/), a US-based international registry that facilitates contact between donor-conceived offspring and their donors. RESULTS: Donors' main reasons for donating were financial payment and wanting to help others. Sperm donors had donated between 1 and 950 times (median = 100) and oocyte donors had donated between 1 and 5 times (median = 2). The majority of sperm donors and more than one-third of oocyte donors expressed concerns about having donated. These concerns were mainly about the well-being of any children conceived using their gametes and not being able to make contact with them. Most sperm and oocyte donors felt that it was important to know how many offspring had been born using their donation, and 51% of sperm donors and 46% of oocyte donors wanted identifying information. All of the donors who had contact with their donor offspring reported positive experiences and the majority continued to have regular contact. CONCLUSIONS: Although the sample may not be representative of all anonymous donors, this study highlights the importance of donors having access to information about their donor offspring and the positive consequences that may arise when contact is made.

Gamete donation: parents' experiences of searching for their child's donor siblings and donor.

BACKGROUND: This study investigates the new phenomenon of parents of donor offspring searching for and contacting their child's 'donor siblings' (i.e. donor offspring conceived by the same donor) and donor. METHODS: Online questionnaires were completed by 791 parents (39% lone-mother, 35% lesbian-couple, 21% heterosexual-couple, 5% non-specified) recruited via the Donor Sibling Registry; a US-based international registry that facilitates contact between donor conception families who share the same donor. Data were collected on parents' reasons for searching for their child's donor siblings and/or donor, the outcome of these searches and parents' and their child's experiences of any resulting contact. RESULTS: Parents' principal motivation for searching for their child's donor siblings was curiosity and for their donor, enhancing their child's sense of identity. Some parents had discovered large numbers of donor siblings (maximum = 55). Most parents reported positive experiences of contacting and meeting their child's donor siblings and donor. CONCLUSIONS: This study highlights that having access to information about a child's donor origins is important for some parents and has potentially positive consequences. These findings have wider implications because the removal of donor anonymity in the UK and elsewhere means that increasing numbers of donor offspring are likely to seek contact with their donor relations in the future.

US oocyte donors: a retrospective study of medical and psychosocial issues.

BACKGROUND: First-person reports of oocyte donors, years after their donation, can give valuable information about medical complications of oocyte donation, as well as changes potentially required in procedures and priorities of US-based in vitro fertilization (IVF) centers. This paper reports findings from an online survey of former oocyte donors. METHODS: The instrument was an author-constructed questionnaire completed online on the Donor Sibling Registry website. Questions assessed women's accounts of medical complications, contact with the infertility clinic through which they had provided ova, and information exchange or contact with people conceived from their ova. RESULTS: Responses were received from 49.1% of the 287 donors with valid e-mail addresses. The 155 respondents completed the survey an average of 9.4 years after their first donation. Reported medical complications included ovarian hypersensitivity syndrome (30.3%) and infertility (9.6%). Subsequent to ova donation, 2.6% of women reported that they had been contacted by the IVF clinic for medical updates. On the questionnaire, 34.2% of women reported that medical changes they thought would interest donor children; half said that they had attempted to report these changes to the clinic with variable results. Many, who did not report such information, did not realize they could or should. Donors said that they frequently had not sought information about pregnancy outcomes because of confusion about the definition of 'anonymity' or 'confidentiality'. CONCLUSIONS: US-based IVF clinics need to give clearer guidelines to anonymous oocyte donors about follow-up information exchange. Additional long-term studies are needed to ascertain oocyte donors' risks of infertility or cancer.

Do endoscopy capsules interfere with implantable cardioverter-defibrillators?

BACKGROUND AND STUDY AIMS: Capsule endoscopy is already an established diagnostic tool, and the newly introduced capsule PillCam COLON is now entering clinical studies. Because of the very limited clinical experience in patients with implantable cardioverter-defibrillators (ICDs), it is generally recommended that capsule endoscopy should not be used in these patients. Therefore, we investigated, in vitro, the possible interference between three different endoscopy capsules (Given Imaging and Olympus) and ICDs. MATERIALS AND METHODS: A total of 45 ICD devices were separately placed in a tank filled with a 0.9 % saline solution. With the help of pin jacks, the pacing pulses of ICDs were recorded and inhibiting signals could be coupled in. The capsules were placed in different positions near to the lead and the ICD device, and finally placed on the case of the device for 1 minute each. The function of each device was observed continuously. RESULTS: Even when the capsules were in closest proximity to the ICDs, no interference was observed. CONCLUSION: The clinical use of the three tested capsule devices is safe in patients with ICDs.

Small-scale preparation of perfluorocarbon-nanoemulsions utilizing dual centrifugation.

BACKGROUND: Perfluorocarbon-nanoemulsions (PFC-NE) made of PFC and phospholipids (PL) by homogenization are optimal for in vivo-19F labelling of monocytes and subsequently of inflamed tissues in magnetic resonance imaging (MRI). Necessary requirements for in vivo use of PFC-NE are sterility, suitable droplet sizes and the absence of immune activating liposomes, which are a typical byproduct of the homogenization process. METHODS AND RESULTS: To meet these requirements, we developed an aseptic in-vial preparation technique for PFC-NE based on dual centrifugation (DC) by testing different PFC/phospholipid ratios as well as the application of additives. Two different PFC, perfluorooctylbromide (PFOB) and perfluoro-15-crown-5-ether (PFCE), were investigated. Particle sizes were assessed by dynamic light scattering and NE morphology by cryoTEM. DC homogenization was optimal when using an excess of PL (8.7 % (m/m) of utilized PFC, z-ave: 180 nm, pdi: 0.2). A purification approach by centrifugation was implemented to remove liposomes formed from the excess of PL during homogenization. The purification success was proven by phospholipid assay and PFC quantification via density and sound velocity measurements. CONCLUSION: DC in combination with a short centrifugation is a fast and reliable way of small-scale aseptic PFC-NE production for 19F MRI passive-targeting experiments of monocytes and inflamed tissues.

Rational manufacturing of functionalized, long-term stable perfluorocarbon-nanoemulsions for site-specific 19F magnetic resonance imaging.

BACKGROUND: Perfluorocarbon (PFC)-nanoemulsions (NE) are a convenient tool for 19F magnetic resonance imaging in cell and animal experiments. Typical preparation methods, like high-pressure homogenization or microfluidization, produce nanoemulsions in mL-scale. However, experiments usually require only miniscule amounts of PFC-NE, several 100 µL. For site-specific imaging tissue-specific ligands, e.g. peptides or antibodies, are covalently bound to the NE surface. This requires the use of expensive functionalized phospholipids containing reactive groups (e.g. maleimide), which often deteriorate quickly in liquid storage, rendering the manufacturing process highly cost-inefficient. A technique to manufacture storage stable NE that maintain their functionality for coupling of various ligands is desired. METHODS AND RESULTS: Different PFC-NE formulations and preparation techniques were compared and the most suitable of these was tested in short-, as well as long-term stability tests. Droplet size stability was investigated by dynamic light scattering and cryogenic transmission electron microscopy over 1.5 a. Surface modifiability was assessed by a fluorescence assay. The utility of these NE was proven in an in vitro model. CONCLUSION: The established PFC-NE platform offers a cost-efficient way to produce larger amounts of long-term storable imaging agents, which can be surface-modified on demand for application in targeted 19F MRI.

Reversal of visceral adiposity in candy-diet fed female Wistar rats by the CB1 receptor antagonist rimonabant.

OBJECTIVE: The severity of obesity is often more determined by the distribution of fat depots rather than by body weight itself. Therefore, the effect of rimonabant on fat distribution pattern was investigated in female candy-fed Wistar rats. DESIGN: Female Wistar rats were fed a high fat, high carbohydrate (candy-) diet for 12 weeks. During the last 6 weeks rats were treated with rimonabant. Food intake and body weight development were investigated, as well as effects on total body fat, especially visceral fat and ectopic lipid accumulation in skeletal muscle and liver, determined by in vivo magnetic resonance imaging/magnetic resonance spectroscopy. RESULTS: Candy-diet increased body weight, which was predominantly due to the increased total fat mass with predominance of visceral fat accumulation. Treatment with rimonabant fully reversed the weight gain and fat deposition in the visceral cavity and skeletal muscle, in contrast to pair feeding. In spite of an only transient reduction of food intake, body weight reduction, as well as normalized body fat, reduced visceral fat and intramyocellular lipids were maintained over the treatment period. CONCLUSIONS: We conclude that additional factors other than reduced caloric intake must be responsible for the improvements in these lipid parameters. The complete cluster of results is consistent with increased lipid oxidation caused by rimonabant.

Capsule endoscopy and cardiac pacemakers: investigation for possible interference.

BACKGROUND AND STUDY AIMS: The diagnostic benefit of capsule endoscopy in suspected small-bowel disease is high and seems to be superior to that with conventional methods and scintigraphy. Because of the limited clinical experience in patients with cardiac pacemakers and other implanted electrical devices, it is recommended that capsule endoscopy should not be used in such cases. We investigated the potential for capsule endoscopy to interfere with cardiac pacemakers in vitro. MATERIAL AND METHODS: 21 different pacemakers and leads were positioned in a 0.9 % saline solution in a tank. Pin jacks were placed that were in contact with the solution. The pacemaker impulse was recorded and an inhibiting signal could be coupled in. The capsules (Given Imaging and Olympus) were placed in different positions relative to the cardiac pacemaker and finally placed on the case of the pacemaker, for 1 minute in each site. The functioning of the pacemaker was observed continuously. The effect on the pacemaker was noted particularly as inhibition, synchronization, or no effect. The pacemaker was then inhibited using a standard test signal. RESULTS: There was no interference between the video capsule and the cardiac pacemakers in our experiment in spite of the close proximity of the two devices. CONCLUSION: The clinical use of capsule endoscopy is unproblematic in patients with cardiac pacemakers.

Minimally invasive pediatric surgery: Increasing implementation in daily practice and resident's training.

BACKGROUND: In 1998, the one-year experience in minimally invasive abdominal surgery in children at a pediatric training center was assessed. Seven years later, we determined the current status of pediatric minimally invasive surgery in daily practice and surgical training. METHODS: A retrospective review was undertaken of all children with intra-abdominal operations performed between 1 January 2005 and 31 December 2005. RESULTS: The type of operations performed ranged from common interventions to demanding laparoscopic procedures. 81% of all abdominal procedures were performed laparoscopically, with a complication rate stable at 6.9%, and conversion rate decreasing from 10% to 7.4%, compared to 1998. There were six new advanced laparoscopic procedures performed in 2005 as compared to 1998. The children in the open operated group were significantly smaller and younger than in the laparoscopic group (p < 0.001 and p = 0.001, respectively). The majority (64.2%) of the laparoscopic procedures were performed by a trainee. There was no difference in the operating times of open versus laparoscopic surgery, or of procedures performed by trainees versus staff surgeons. Laparoscopy by trainees did not have a negative impact on complication or conversion rates. CONCLUSIONS: Laparoscopy is an established approach in abdominal procedures in children, and does not hamper surgical training.

Fetal urogenital sinus with consecutive hydrometrocolpos because of labial fusion: prenatal diagnostic difficulties and postpartal therapeutic management.

OBJECTIVE: To elucidate the differential diagnoses of tumorous dilations in the fetal pelvic region detected by prenatal ultrasound and the postnatal management demonstrated on a fetus with 29 weeks of gestation with a retrovesical located bottle-like cystic structure measuring 54 x 31 x 27 mm within the pelvis. Postnatal findings were a labial fusion and a consecutive hydrometrocolpos due to a urethrovaginal fistula. METHOD: Case report of a fetus affected by an intricate cloacal anomaly. RESULTS: The long-term prognosis for this nonsyndromic form of hydrometrocolpos without any other structural defects or organic failures after operative sanitation is excellent. Final reconstruction is planned at about 12 months of age. CONCLUSION: Prenatal diagnosis of tumorous dilations in the fetal pelvic region often involves difficulties because of numerous differential diagnoses and possible presentation in late pregnancy. Magnetic resonance imaging could be a useful complementary tool for assessing these anomalies when ultrasonography is inconclusive. In some cases, the final diagnosis cannot be confirmed until after delivery.

Arginine-glycine-aspartic acid- and fibrinogen gamma-chain carboxyterminal peptides inhibit platelet adherence to arterial subendothelium at high wall shear rates. An effect dissociable from interference with adhesive protein binding.

Arg-Gly-Asp (RGD)- and fibrinogen gamma-chain carboxyterminal (GQQHHLGGAKQAGDV) peptides inhibit fibrinogen, fibronectin (Fn), vitronectin, and von Willebrand factor (vWF) binding to the platelet glycoprotein IIb-IIIa complex (GP IIb-IIIa). GP IIb-IIIa, vWF, and Fn are essential for normal platelet adherence to subendothelium. We added peptides to normal citrated whole blood before perfusion over human umbilical artery subendothelium and evaluated platelet adherence morphometrically at high (2,600 s-1) and low (800 s-1) wall shear rates. We also examined the effects of the peptides on platelet adhesion to collagen in a static system. At the high wall shear rate, RGDS and GQQHHLGGAKQAGDV caused dose-dependent reduction in the surface coverage with spread and adherent platelets. Amino acid transposition and conservative substitutions of RGD peptides and the AGDV peptide significantly inhibited platelet adherence at 2,600 s-1. By contrast, the modified RGD peptides and AGDV do not affect adhesive protein binding to platelets. None of the native or modified RGD- or fibrinogen gamma-chain peptides significantly inhibited either platelet adherence to subendothelium at 800 s-1 or platelet adhesion to collagen. Our findings demonstrate that peptides that interfere with adhesive protein binding to GP IIb-IIIa inhibit platelet adherence to vascular subendothelium with flowing blood only at high wall shear rates. Platelet adherence to subendothelium at high wall shear rates appears to be mediated by different recognition specificities from those required for fluid-phase adhesive protein binding or static platelet adhesion.

Heteroduplex DNA correction in Saccharomyces cerevisiae is mismatch specific and requires functional PMS genes.

In vitro-constructed heteroduplex DNAs with defined mismatches were corrected in Saccharomyces cerevisiae cells with efficiencies that were dependent on the mismatch. Single-nucleotide loops were repaired very efficiently; the base/base mismatches G/T, A/C, G/G, A/G, G/A, A/A, T/T, T/C, and C/T were repaired with a high to intermediate efficiency. The mismatch C/C and a 38-nucleotide loop were corrected with low efficiency. This substrate specificity pattern resembles that found in Escherichia coli and Streptococcus pneumoniae, suggesting an evolutionary relationship of DNA mismatch repair in pro- and eucaryotes. Repair of the listed mismatches was severely impaired in the putative S. cerevisiae DNA mismatch repair mutants pms1 and pms2. Low-efficiency repair also characterized pms3 strains, except that correction of single-nucleotide loops occurred with an efficiency close to that of PMS wild-type strains. A close correlation was found between the repair efficiencies determined in this study and the observed postmeiotic segregation frequencies of alleles with known DNA sequence. This suggests an involvement of DNA mismatch repair in recombination and gene conversion in S. cerevisiae.