Absence of conception after caesarean section: voluntary or involuntary?

BACKGROUND

Women who deliver by caesarean section have been shown to be less likely to have a subsequent pregnancy. It is not clear whether this is due to a direct effect of the procedure on future fertility or due to deliberate avoidance of a future pregnancy.

OBJECTIVE

To investigate whether absence of conception following caesarean section is voluntary or involuntary.

DESIGN

Follow up of a population-based retrospective cohort.

SETTING

Grampian region, Scotland.

POPULATION

Women who had no further viable pregnancies within 5 years of an initial delivery.

METHODS

Cases included women who delivered their first child by caesarean section between 1980 and 1995 but had no further viable pregnancies by December 2000. Controls included women who delivered their first child during the same period, by means of either spontaneous vaginal delivery (SVD) or instrumental vaginal delivery (IVD), and who had no further viable pregnancies by December 2000. Eligible women were identified from the Aberdeen Maternity and Neonatal Databank (AMND) and sent postal questionnaires to determine the extent to which not conceiving after first delivery was voluntary and the reasons for avoiding further pregnancies. Characteristics of the different mode of delivery groups were compared using univariate techniques.

MAIN OUTCOME MEASURES

Extent to which absence of conception following an initial delivery by caesarean section is voluntary.

RESULTS

Questionnaires were returned by 3204 (60%) of 5300 women identified from the AMND. Of these, 1675 women had not conceived at all during the follow-up period (median duration = 13 years). Absence of conception was voluntary in 488 (69%; 95% CI 66-73%) women following caesarean section, 340 (71%; 95% CI 67-76%) following SVD and 354 (72%; 95% CI 68-76%) following IVD. Few women considered seeking fertility treatment (caesarean section = 72 [10%], SVD = 50 [11%], IVD = 39 [8%]). Of the women who decided to delay or avoid a further pregnancy, fewer women who delivered by SVD reported that the birth experience influenced their decision (caesarean section = 163 [32%], SVD = 67 [18%], IVD = 136 [35%]; P < 0.001).

CONCLUSIONS

Irrespective of mode of delivery, not conceiving following the birth of the first child is mainly voluntary. The experience of the previous birth is one of several factors affecting women's decisions to avoid a subsequent pregnancy.

Primary mode of delivery and subsequent pregnancy

OBJECTIVE

To investigate the relationship between primary mode of delivery and subsequent pregnancy and to compare the findings with a previous study conducted on an earlier cohort from the same population.

DESIGN

Population cohort.

SETTING

Aberdeen City, Scotland.

POPULATION

Women who delivered their first singleton child in Aberdeen Maternity Hospital between 1980 and 1997.

METHODS

Population-based data relating to the index and next pregnancy event, if any, were obtained from the Aberdeen Maternity Neonatal Databank. Subsequent pregnancy was compared across the three modes of delivery groups using log rank tests and Cox proportional hazards regression models.

MAIN OUTCOME MEASURE

First subsequent pregnancy following index delivery.

RESULTS

Women who delivered by caesarean section (CS) were less likely to have a subsequent pregnancy compared with those who had a spontaneous vaginal delivery (SVD), hazard ratio = 0.91 (95% CI 0.87, 0.95). This confirmed the findings of a previous study conducted on an earlier cohort of the same population. The median time to next pregnancy following CS was 36.3 months, 31.8 months following instrumental vaginal delivery (IVD) and 30.4 months following SVD. In contrast to the earlier study where women who had an instrumental delivery were found to be an intermediate group, we found no difference in subsequent pregnancy following IVD compared with SVD, HR = 1.0 (95% CI 0.96, 1.03).

CONCLUSIONS

Following an initial delivery by CS, fewer women went on to have another pregnancy compared with SVD. The incidence of subsequent pregnancy is similar following instrumental and SVD.

Evolution of cemented stems

John Charnley was responsible for pioneering successful cemented hip arthroplasty. Changes in stem design were made in response to early complications such as stem fracture. Various philosophies of stem biomechanics emerged, namely stems performing in the taper slip mode and stems performing as a composite beam. Both stem designs may be successful, although it is important not to mix biomechanical philosophies. Later evolutions have occurred in response to surgical flexibility, specifically modularity and offset options. These attributes can impart new demands on the stem and, in some cases, retrograde developments have occurred. Cemented stems may yield excellent long-term results and have the potential to limit fixation to the proximal femur and establish a metaphyseal-loading regimen. The latest design of taper slip stems, such as the C-stem (DePuy Orthopaedics, Warsaw, Ind), may have advantages in maintaining proximal bone stock and preserving host bone. The historical developments and evolution of the cemented stem in total hip arthroplasty (THA) are discussed.

Visual search: efficiency continuum or distinct processes?

Whether visual search involves two distinct processes--traditionally referred to as serial and parallel--or a single process operating on a continuum of efficiency or speed, is an issue with a long history in the study of attention. On the basis of the unimodality of search slope distributions in a very large data set, Wolfe (1998) argued for a continuum model. Reanalysis of this data set using statistical procedures more appropriate for adjudicating between continuous and discontinuous models supports the existence of two distinct processes.

Forced displacement in Yugoslavia: a meta-analysis of psychological consequences and their moderators

A meta-analysis was conducted to synthesize what is known about differences in mental health between refugees and nonrefugees from the former Yugoslavia. The analysis focused on moderating effects of a variety of enduring, contextual stressors. Results indicated that refugees suffer significantly more mental health impairment than nonrefugees. The psychological consequences of forced displacement were found to vary significantly as a function of chronic stressors (e.g., locus of displacement and type of accommodation in exile) and were also associated with otherfactors (e.g., degree of war exposure in the nondisplaced groups, participant age, and time of data collection as reflected in year of publication). Implications for the study of refugee mental health are discussed.

Genomic structure of three CLN3-like genes in Caenorhabditis elegans

The genome of Caenorhabditis elegans is predicted to carry three genes similar to CLN3, the gene underlying juvenile neuronal ceroid lipofuscinosis. All three genes are transcribed and the genomic structure has been determined. The number and position of exons for two of the genes differ from that predicted from the genomic sequence, but no discrepancies with the genomic nucleotide sequence were found. Gene F07B10.1 (cln-3.1) is predicted to have 7 exons and to encode a protein of 424 amino acids. Gene C01G8.2 (cln-3.2) has 9 exons and encodes a protein of 435 amino acids. Gene ZC190.1 (cln-3.3) is predicted to have 9 exons and to encode a protein of 416 amino acids.

Improving SH3 domain ligand selectivity using a non-natural scaffold

BACKGROUND

Src homology 3 (SH3) domains bind sequences bearing the consensus motif PxxP (where P is proline and x is any amino acid), wherein domain specificity is mediated largely by sequences flanking the PxxP core. This specificity is limited, however, as most SH3 domains show high ligand cross-reactivity. We have recently shown that diverse N-substituted residues (peptoids) can replace the prolines in the PxxP motif, yielding a new source of ligand specificity.

RESULTS

We have tested the effects of combining multiple peptoid substitutions with specific flanking sequences on ligand affinity and specificity. We show that by varying these different elements, a ligand can be selectively tuned to target a single SH3 domain in a test set. In addition, we show that by making multiple peptoid substitutions, high-affinity ligands can be generated that completely lack the canonical PxxP motif. The resulting ligands can potently disrupt natural SH3-mediated interactions.

CONCLUSIONS

Peptide-peptoid hybrid scaffolds yield SH3 ligands with markedly improved domain selectivity, overcoming one of the principal challenges in designing inhibitors against these domains. These compounds represent important leads in the search for orthogonal inhibitors of SH3 domains, and can serve as tools for the dissection of complex signaling pathways.

Individualized care: perceptions of certified nurse's aides

Despite substantial attention devoted to the development of individualized care in nursing homes during recent years, empirical research assessing progress is limited. Further, few studies have explored the experiences of certified nurse's aides (CNAs) in this regard. This survey examines the perceptions and experiences of CNAs in providing individualized care. CNAs (n = 254) were asked to describe a number of current practices and obstacles to implementing individualized care in nursing homes. The majority of respondents reported experiencing: flexibility to change daily schedules; supervisor assistance with challenging residents; active participation in care planning; freedom to test new approaches to care; and supervisors who are open to CNA suggestions. Several barriers to individualized care were also described, including: inadequate staffing; poor team communication; staff attitudes; and a lack of knowledge and training in alternative approaches. These findings provide important insights into the supports and obstacles to implementing individualized care in nursing homes from the perspective of CNAs.

Effects of melatonin on liver estrogen receptor and vitellogenin expression in rainbow trout: an in vitro and in vivo study

Although melatonin is believed to mediate many seasonal and circadian effects of photoperiod on reproduction in salmonids, the precise mechanisms underlying such effects are still largely unknown. Recent data of the literature indicate a relationship between melatonin and expression of estrogen receptors (ER) in various tissues. In this study, the effects of melatonin on estrogen receptor and/or vitellogenin expression were studied by a combination of in vivo and in vitro experiments. In yeast stably expressing ER and transfected with an estrogen-responsive element-beta-galactosidase reporter gene, melatonin had no effect on basal or E2-stimulated ER expression. Incubation of hepatocyte aggregates with melatonin (10(-8) to 10(-4)) for 16 or 48 h did not modify the E2-stimulated ER and vitellogenin mRNA, as measured by dot blots. Finally, neither pinealectomy nor melatonin implants caused any effect on basal or E2-stimulated ER and vitellogenin mRNA contents in the liver. Altogether, these results suggest that, although we cannot exclude potential effects at the brain or pituitary levels, melatonin has no or little effects on estrogen receptor in the liver.

Reciprocal regulation of Hck activity by phosphorylation of Tyr(527) and Tyr(416). Effect of introducing a high affinity intramolecular SH2 ligand

The Src family tyrosine kinase Hck possesses two phosphorylation sites, Tyr(527) and Tyr(416), that affect the catalytic activity in opposite ways. When phosphorylated, Tyr(527) and residues C-terminal to it are involved in an inhibitory intramolecular interaction with the SH2 domain. However, this sequence does not conform to the sequence of the high affinity SH2 ligand, pYEEI. We mutated this sequence to YEEI and show that this mutant form of Hck cannot be activated by exogenous SH2 ligands. The SH3 domain of Hck is also involved in an inhibitory interaction with the catalytic domain. The SH3 ligand Nef binds to and activates YEEI-Hck mutant in a similar manner to wild-type Hck, indicating that disrupting the SH3 interaction overrides the strengthened SH2 interaction. The other phosphorylation site, Tyr(416), is the autophosphorylation site in the activation loop. Phosphorylation of Tyr(416) is required for Hck activation. We mutated this residue to alanine and characterized its catalytic activity. The Y416A mutant shows a higher K(m) value for peptide and a lower V(max) than autophosphorylated wild-type Hck. We also present evidence for cross-talk between the activation loop and the intramolecular binding of the SH2 and SH3 domains.

Mapping genes that control hormone-induced ovulation rate in mice

The present study mapped quantitative trait loci (QTL) that control 6-fold genetic differences in hormone-induced ovulation rate (HIOR) between C57BL/6J (B6) (HIOR = 54) and A/J strain mice (HIOR = 9). (The gene name is Ovulation Rate Induced [ORI] QTL and the gene symbol is Oriq.) QTL linkage analysis was conducted on 167 (B6xA)xA backcross mice at 165 loci. Suggestive B6 ORI QTL that control the number of eggs in cumulus mapped, as follows, near: Cyp19 and D9Mit4 on chromosome (Chr) 9 (Oriq1); D2Mit433 on Chr2 (Oriq2); D6Mit316 on Chr6 (Oriq3); DXMit22 on ChrX (Oriq4) and were associated with a 2.7, 2.7, 2.6, and 4.2 egg increases in HIOR, respectively. Oriq3 was significant (LOD = 3.45) based on composite interval mapping. QTL linkage analysis of the number of eggs matured by endogenous gonadotropins and ovulated by eCG mapped a significant Oriq5 to Chr 10 and suggestive Oriq to Chr 6, 7, and X. These data provide the first molecular genetic markers for reproductive QTL that control major differences in ovarian responsiveness to gonadotropins. These and closely linked syntenic molecular markers will enable a more accurate prediction of ovarian responsiveness to gonadotropins and provide selection criteria for improving reproductive performance in diverse mammalian species.

Plasmin cleavage of the amyloid beta-protein: alteration of secondary structure and stimulation of tissue plasminogen activator activity

Cerebrovascular amyloid beta-protein (A beta) deposition, a key pathological feature of Alzheimer's disease and hereditary cerebral hemorrhage with amyloidosis Dutch-type, can lead to intracerebral hemorrhage; however, the mechanism for this remains unclear. Assembled A beta is a potent stimulator of tissue-type plasminogen activator (tPA) in vitro. Herein, we investigated the stimulation of tPA by freshly solubilized A beta 1-40. The rate of tPA stimulation by A beta 1-40 increased dramatically over time, suggesting that A beta may be altered during the course of the reaction. SDS-PAGE analysis showed that A beta 1-40 was cleaved during the course of the reaction. Subsequent studies showed that it was plasmin, the product of tPA activation of plasminogen, that specifically cleaved A beta 1-40 in the amino terminal region between Arg5 and His6. Plasmin effectively cleaved a chromogenic substrate corresponding to this cleavage site in A beta. Circular dichroism spectral analysis showed that A beta 6-40 adopted a strong beta-sheet secondary structure. This truncated A beta 6-40 peptide was a potent stimulator of tPA in vitro. Our results indicate that beta-sheet secondary structure of A beta, which can be promoted by plasmin cleavage, stimulates tPA activity. These findings suggest that pathologic interactions between A beta, tPA, and plasmin in the cerebral vessel wall could result in excessive proteolysis contributing to intracerebral hemorrhages.

Developing individualized care in nursing homes: integrating the views of nurses and certified nurse aides

Despite recent attention devoted to the development of individualized care in nursing homes, empirical research assessing changes in practice is quite limited, and very few studies have explored specifically the experiences and perceptions of certified nurse aides (CNAs). This study reports findings from a comparative analysis conducted on a data set including quantitative and qualitative data from CNAs (N = 289) and nurses in Connecticut (N = 245). Measures of obstacles to individualized care and needs for future supports were explored. A number of significant differences in perceptions of obstacles to providing individualized care were found. The nurses were significantly more likely to identify the following impediments to change: cost (p < .0001), concepts not integrated into work (p < .0001), lack of administrative support (p < .10), and staff attitudes (p < .10). The CNAs were significantly more likely to report inadequate staffing (p < .001), lack of interdisciplinary teams (p < .001), and resident and family attitudes (p < .01) as problematic. These findings suggest substantial discordance among nurses and CNAs on a number of important issues surrounding individualized care. Such disparate perceptions pose challenges to nursing homes committed to the implementation of individualized care alternatives. Successful approaches must consider the various vantage points of caregivers and administrators.

Variable dose naltrexone-induced hypothalamic-pituitary-adrenal stimulation in abstinent alcoholics: a preliminary study

Opiate antagonists have been found to stimulate the hypothalamic-pituitary-adrenal axis. However, despite established usefulness in the management of alcoholism, systematic, oral dose-titrated natrexone-induced hypothalamic-pituitary-adrenal stimulation has never been studied in alcoholics. Six patients (5 males, 1 female) with DSM-IV alcohol dependence, who were at least 4 weeks abstinent from any alcohol [mean 55 days (+/-SE 7.5)], were given four challenges of oral naltrexone (0, 25, 50, and 100 mg) in a randomized order at least 3 days apart, after an overnight fast. Naltrexone was administered at 9 AM; serum ACTH, cortisol, and prolactin were measured at time 0 and at 9 time points over the next 4 hr. Subjects also filled out a side effect questionnaire and an alcohol urge questionnaire. Physiological measurements of blood pressure and pulse rate were taken at the same time points. Repeated-measures ANOVA of the changes in serum ACTHs over time revealed a significant effect of drug (placebo vs. any dose of naltrexone) (p < 0.05). Post-hoc analysis revealed a significant difference between placebo and the 25 mg dose (p < 0.01), the 50 mg dose (p < 0.01), but no significance between the placebo and the 100 mg dose (p = 0.1). A repeated-measures ANOVA of the changes in serum cortisols over time revealed a significant effect of drug (p < 0.01). Post-hoc analysis revealed a significant difference between placebo and the 25 mg dose (p < 0.01), between placebo and the 50 mg dose (p < 0.05), and placebo and the 100 mg dose (p < 0.01). There was a significant between dose difference in pulse rate changes over baseline (p < 0.01), and post-hoc analysis revealed a significant diminution in pulse rate at the 100 mg dose relative to placebo (p < 0.001), and to the other doses. There were no significant differences in reported side effects, alcohol urge questionnaire scores, or in other physiological measurements between doses. These data suggest a significant rise in ACTH and cortisol in response to naltrexone in alcoholics compared with placebo, with no differences between 25 mg, 50 mg, and 100 mg doses, and a significant diminution in pulse rate responses at the 100 mg dose.

Intramolecular regulatory interactions in the Src family kinase Hck probed by mutagenesis of a conserved tryptophan residue

Intramolecular interactions between the Src homology domains (SH2 and SH3) and the catalytic domains of Src family kinases result in repression of catalytic activity. The crystal structure of the Src family kinase Hck, with its regulatory domains intact, has been solved. It predicts that a conserved residue, Trp260, at the end of the linker between the SH2 and the catalytic domains plays an important role in regulation by the SH3 and SH2 domains. We have mutated this residue and compared the activities of C-terminally phosphorylated wild type Hck and W260A Hck. The W260A mutant has a higher specific activity than wild type Hck. The W260A mutant requires autophosphorylation at Tyr416 for full activity, but it is not activated by ligand binding to the SH3 or SH2 domains. This mutation also changes the accessibility of the SH2 and SH3 domains to their cognate peptide ligands. Our results indicate that Trp260 plays a critical role in the coupling of the regulatory domains to the catalytic domain, as well as in positioning the ligand binding surfaces.

Nalmefene causes greater hypothalamic-pituitary-adrenal axis activation than naloxone in normal volunteers: implications for the treatment of alcoholism

Among other actions, opioid antagonists modulate the control endogenous opioids exert on the hypothalamic-pituitary-adrenal (HPA) axis. Naloxone, nalmefene, and naltrexone are the opioid antagonists approved for use in man and are primarily mu-opioid selective. Naltrexone and nalmefene have been demonstrated to be useful in the treatment of alcoholism. Compared with naloxone, nalmefene has a longer half-life, is more potent at the mu-receptor, and has a higher affinity for kappa- and delta-opioid receptors. We conducted an inpatient study comparing the effects of 10 and 30 mg doses of intravenous naloxone and nalmefene in normal, nonsubstance nor alcohol-abusing, volunteers. Significant increases in ACTH and cortisol were observed after both antagonists, without an apparent dose-response relationship; however, both doses of nalmefene resulted in greater HPA axis activation than either dose of naloxone (ACTH: p <0.005). These results indicate that kappa- and delta-opioids may play important roles in the regulation of the HPA axis; nalmefene may be useful as both a probe to explore the HPA axis physiology and as a pharmacotherapeutic agent.

A matter of methods: perspectives on the role of the British general practitioner in the care of people with HIV/AIDS

This paper is a critique of, and a comment on, the debate about the role of British general practitioners (GPs) in HIV care. We argue that (1) this debate is conducted around arguments which leave significant aspects of GPs' contribution undocumented and unnoticed, and that (2) research has contributed to this omission. The paper reviews the history of the debate about GPs' involvement in HIV care and argues that social research using structured survey methods has reinforced the continuing negative image of GP care. The paper draws on an ethnographic research project in Lothian (Scotland) which found that many people with HIV strongly valued their ongoing personal relationship with their GP. People with HIV also valued the hospital-based outreach system which provided reliable and high quality care, but sometimes experienced the associated interprofessional information sharing and discussion as invasive and controlling. Their GP relationship was valued because it was outside this hospital-based system of care. The paper concludes by suggesting that future developments in GP care should build on this positive aspect of the GP-patient relationship.

Self-recorded stress levels for general practitioners before and after forming an out-of-hours primary care centre

The Nottingham Stress-Arousal Checklist (SACL) was used to compare stress and arousal levels within a group of 36 Scottish general practitioners (GPs) before and after an out-of-hours primary care centre opened in 1995. Overall, GPs reported significantly lower stress and higher arousal scores with the new service.