To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
How neighbourhood characteristics affect the physical safety of people with mental illness is unclear.
To examine neighbourhood effects on physical victimisation towards people using mental health services.
We developed and evaluated a machine-learning-derived free-text-based natural language processing (NLP) algorithm to ascertain clinical text referring to physical victimisation. This was applied to records on all patients attending National Health Service mental health services in Southeast London. Sociodemographic and clinical data, and diagnostic information on use of acute hospital care (from Hospital Episode Statistics, linked to Clinical Record Interactive Search), were collected in this group, defined as ‘cases’ and concurrently sampled controls. Multilevel logistic regression models estimated associations (odds ratios, ORs) between neighbourhood-level fragmentation, crime, income deprivation, and population density and physical victimisation.
Based on a human-rated gold standard, the NLP algorithm had a positive predictive value of 0.92 and sensitivity of 0.98 for (clinically recorded) physical victimisation. A 1 s.d. increase in neighbourhood crime was accompanied by a 7% increase in odds of physical victimisation in women and an 13% increase in men (adjusted OR (aOR) for women: 1.07, 95% CI 1.01–1.14, aOR for men: 1.13, 95% CI 1.06–1.21, P for gender interaction, 0.218). Although small, adjusted associations for neighbourhood fragmentation appeared greater in magnitude for women (aOR = 1.05, 95% CI 1.01–1.11) than men, where this association was not statistically significant (aOR = 1.00, 95% CI 0.95–1.04, P for gender interaction, 0.096). Neighbourhood income deprivation was associated with victimisation in men and women with similar magnitudes of association.
Neighbourhood factors influencing safety, as well as individual characteristics including gender, may be relevant to understanding pathways to physical victimisation towards people with mental illness.
A recent systematic review found a high prevalence of violence and mental distress among women trafficked for sexual exploitation; no data were identified for trafficked men and children.
To describe the clinical characteristics of trafficked people in contact with a large inner city mental health service compared with a non-trafficked cohort.
To investigate whether, compared with a non-trafficked cohort, trafficked people would be significantly more likely to have co-morbid disorders and have significantly smaller improvements in functioning at the end of an episode of care.
Study population: mental health service users who had been trafficked for exploitation and a non-trafficked service user cohort matched for gender and age. Data source: The South London and Maudsley NHS Trust (SLaM) Biomedical Research Centre Case Register Interactive Search (CRIS) database of anonymised full patient records (2006–2012).
We identified case records of 135 people who had been trafficked. 104 (77%) were female; age at first SLaM contact ranged from 8 to 49 years (mean 23.6, SD 8.0). 38 (28%) of the trafficked service users received psychiatric care from an emergency department. Depression (28.1%, n = 38), PTSD (19.3%, n = 26), non-affective psychoses (12.6%, n = 17) were the most frequently recorded diagnoses among trafficked service users. Further analysis is in progress and scheduled for completion by March 2013.
Significant numbers of trafficked people were seen in an inner-city mental health service; services therefore need to understand their complex needs.
Higher all-cause mortality and shorter life expectancies for people with severe mental illness (SMI, including schizophrenia, schizoaffective disorder, and bipolar disorder) have been frequently reported. Cancer contributes a substantial proportion of mortality (20 to 30%) as the second or third leading cause of death among people with SMI. Outcomes of cancer incidence studies in SMI were considerably heterogeneous, varying by cancer types and mental disorders.
To compare the incidence of overall and each type of cancer between people with SMI in southeast London and general population in UK.
Using the anonymised linkage between a regional monopoly secondary mental health service provider covering four southeast London boroughs and a population-based cancer register, we carried out the comparisons of cancer incidences between people with SMI and general population by age- and gender-standardisation in 2011.
Among SMI subjects with cancer (N=105), the most common cancer types were lung and colorectal cancer followed by breast cancer for women and prostate cancer for men in this area. Standardised incidence ratios (SIRs) for all cancers in SMI were 1.19 (95% CI: 0.97-1.44) overall, 2.43 (95% CI: 1.98-2.94) in men (n=61), and 0.98 (95% CI: 0.71-1.31) in women (n=44). Based on relatively small case numbers, raised SIRs were found for lung cancer in men (SIR=7.57, 95% CI: 3.04-15.6) and women (SIR=7.61, 95% CI: 2.79-16.6), and in women for colorectal (SIR=7.85, 95%CI: 2.55-18.32) and breast cancer (SIR=7.86, 95% CI: 4.58-12.59).
Specific pattern of elevated risks of cancer incidence were found for people with SMI.
Compared to the general population, people with schizophrenia have a substantially higher risk of premature mortality which translates into a 10–15 year reduction in life expectancy. The aim of this investigation was to determine if symptoms (including aggression, hallucinations or delusions, and depression) or the environmental and functional status of people with schizophrenia contribute to the high mortality risk observed in this patient group.
We identified cases of schizophrenia, aged ≥15 years in a large secondary mental healthcare case register linked to national mortality tracing. We modelled the effect of specific symptoms, activities of daily living (ADLs), living conditions, occupational and recreational activities (Health of the Nation Outcome Scale [HoNOS] subscales) on all-cause mortality over a 4-year observation period (2007-10) using Cox regression.
We identified 4270 schizophrenia cases (170 deaths) in the observation period. After controlling for a broad range of covariates, mortality was not significantly associated with hallucinations and delusions or overactive-aggressive behaviour, but was associated with subclinical depression (adjusted HR 1.5; 95% CI 1.1-2.2) and ADL impairment (adjusted HR 1.8; 95% CI 1.2-2.9).
Severity of symptoms, such as delusions and hallucinations, was less important in predicting mortality than subclinical depression and difficulties carrying out activities of daily living. The overall picture appears to be one where the highest all-cause mortality risk is in service users who are least visible to clinical teams.
Longitudinal cognitive change before and after acetyl cholinesterase inhibitor (AChEI) treatment initiation in Alzheimer's disease has never been described previously in a representative clinical population.
To model longitudinal changes in cognitive function for before and after AChEI prescription.
To further investigate differences in response by cognitive function at treatment initiation.
A retrospective longitudinal analysis was carried out of all 1843 patients from the South London and Maudsley NHS Foundation Trust (a large mental health provider to a catchment population of approximately 1.2 m) who were prescribed AChEIs between 2003–10 and had a minimum of one MMSE score within 1 year before treatment initiation and one MMSE score within 3 years after this. Manually extracted MMSE scores were analyzed over this period using three-piece linear mixed models.
Rates of MMSE change were −1.9 (95% CI −2.3,−1.4) in the year before treatment initiation, +1.3 (0.9,1.7) in the 6 months after treatment initiation, and −2.4 (−2.6,−2.3) from 6 months to 3 years. The difference between pre-treatment and 6-month-post-treatment slopes was −0.6 (−1.8,0.6) at baseline (treatment initiation) MMSE of 25 or over, +2.7 (1.7,3.7) at MMSE 21–24, and +4.6 (3.6,5.7) at MMSE 10–20.
In this naturalistic sample, a clear cognitive response to AChEI treatment was observed over the first six months followed by an unchanged decline. Response was substantially higher for patients with lower MMSE scores at treatment initiation.
The symptoms of bipolar disorder are sometimes misrecognised for unipolar depression and inappropriately treated with antidepressants. This may be associated with increased risk of developing mania. However, the extent to which this depends on what type of antidepressant is prescribed remains unclear.
To investigate the association between different classes of antidepressants and subsequent onset of mania/bipolar disorder in a real-world clinical setting.
Data on prior antidepressant therapy were extracted from 21,012 adults with unipolar depression receiving care from the South London and Maudsley NHS Foundation Trust (SLaM). multivariable Cox regression analysis (with age and gender as covariates) was used to investigate the association of antidepressant therapy with risk of developing mania/bipolar disorder.
In total, 91,110 person-years of follow-up data were analysed (mean follow-up: 4.3 years). The overall incidence rate of mania/bipolar disorder was 10.9 per 1000 person-years. The peak incidence of mania/bipolar disorder was seen in patients aged between 26 and 35 years (12.3 per 1000 person-years). The most frequently prescribed antidepressants were SSRIs (35.5%), mirtazapine (9.4%), venlafaxine (5.6%) and TCAs (4.7%). Prior antidepressant treatment was associated with an increased incidence of mania/bipolar disorder ranging from 13.1 to 19.1 per 1000 person-years. Multivariable analysis indicated a significant association with SSRIs (hazard ratio 1.34, 95% CI 1.18–1.52) and venlafaxine (1.35, 1.07–1.70).
In people with unipolar depression, antidepressant treatment is associated with an increased risk of subsequent mania/bipolar disorder. These findings highlight the importance of considering risk factors for mania when treating people with depression.
Disclosure of interest
The authors have not supplied their declaration of competing interest.
Mood instability is an important problem but has received relatively little research attention. Natural language processing (NLP) is a novel method, which can used to automatically extract clinical data from electronic health records (EHRs).
To extract mood instability data from EHRs and investigate its impact on people with mental health disorders.
Data on mood instability were extracted using NLP from 27,704 adults receiving care from the South London and Maudsley NHS Foundation Trust (SLaM) for affective, personality or psychotic disorders. These data were used to investigate the association of mood instability with different mental disorders and with hospitalisation and treatment outcomes.
Mood instability was documented in 12.1% of people included in the study. It was most frequently documented in people with bipolar disorder (22.6%), but was also common in personality disorder (17.8%) and schizophrenia (15.5%). It was associated with a greater number of days spent in hospital (B coefficient 18.5, 95% CI 12.1–24.8), greater frequency of hospitalisation (incidence rate ratio 1.95, 1.75–2.17), and an increased likelihood of prescription of antipsychotics (2.03, 1.75–2.35).
Using NLP, it was possible to identify mood instability in a large number of people, which would otherwise not have been possible by manually reading clinical records. Mood instability occurs in a wide range of mental disorders. It is generally associated with poor clinical outcomes. These findings suggest that clinicians should screen for mood instability across all common mental health disorders. The data also highlight the utility of NLP for clinical research.
Disclosure of interest
The authors have not supplied their declaration of competing interest.
There are often substantial delays before diagnosis and initiation of treatment in people bipolar disorder. Increased delays are a source of considerable morbidity among affected individuals.
To investigate the factors associated with delays to diagnosis and treatment in people with bipolar disorder.
Retrospective cohort study using electronic health record data from the South London and Maudsley NHS Foundation Trust (SLaM) from 1364 adults diagnosed with bipolar disorder. The following predictor variables were analysed in a multivariable Cox regression analysis on diagnostic delay and treatment delay from first presentation to SLaM: age, gender, ethnicity, compulsory admission to hospital under the UK Mental Health Act, marital status and other diagnoses prior to bipolar disorder.
The median diagnostic delay was 62 days (interquartile range: 17–243) and median treatment delay was 31 days (4–122). Compulsory hospital admission was associated with a significant reduction in both diagnostic delay (hazard ratio 2.58, 95% CI 2.18–3.06) and treatment delay (4.40, 3.63–5.62). Prior diagnoses of other psychiatric disorders were associated with increased diagnostic delay, particularly alcohol (0.48, 0.33–0.41) and substance misuse disorders (0.44, 0.31–0.61). Prior diagnosis of schizophrenia and psychotic depression were associated with reduced treatment delay.
Some individuals experience a significant delay in diagnosis and treatment of bipolar disorder, particularly those with alcohol/substance misuse disorders. These findings highlight a need to better identify the symptoms of bipolar disorder and offer appropriate treatment sooner in order to facilitate improved clinical outcomes. This may include the development of specialist early intervention services.
Disclosure of interest
The authors have not supplied their declaration of competing interest.
We conducted unmanned aerial vehicle lidar missions in the Maya Lowlands between June 2017 and June 2018 to develop appropriate methods, procedures, and standards for drone lidar surveys of ancient Maya settlements and landscapes. Three site locations were tested within upper Usumacinta River region using Phoenix Lidar Systems: Piedras Negras, Guatemala, was tested in 2017, and Budsilha and El Infiernito, both in Mexico, were tested in 2018. These sites represent a range of natural and cultural contexts, which make them ideal to evaluate the usefulness of the technology in the field. Results from standard digital elevation and surface models demonstrate the utility of deploying drone lidar in the Maya Lowlands and throughout Latin America. Drone survey can be used to target and efficiently document ancient landscapes and settlement. Such an approach is adaptive to fieldwork and is cost effective but still requires planning and thoughtful evaluation of samples. Future studies will test and evaluate the methods and techniques for filtering and processing these data.
Until recently, the main selection focus in UK dairy goats has been on milk yield. To develop a selection index suitably weighted for a variety of traits, it is important to understand the genetic relationships between production, health and fertility traits. This study focussed on three aspects of reproduction that are of interest to goat breeders. (1) Out of season (OOS) kidding ability: goats are highly seasonal breeders so achieving consistent, year-round dairy production presents a challenge. It may be possible to select for extended or shifted breeding cycles, however, there are no published studies on the genetic basis of seasonal kidding ability, and a genetic correlation with milk production in dairy goats; (2) age at first kidding (AFK): a reduced AFK offers the opportunity for more rapid genetic improvement, as well as reducing the amount of time and resources required to raise the animals to producing age; (3) pseudopregnancy (PPG): as it is difficult to diagnose pregnancy within 30 days of mating, high herd levels of PPG could add a significant delay in breeding replacement animals, or commencing a new lactation. Using records from 9546 goats, the objective of this study was to investigate the genetic relationships between the reproductive traits described above, and the production traits 520-day milk yield (MY520), lifetime milk yield (MYLife) and lifetime number of days in milk (DIMLife). The ‘out of season’ phenotype was defined as week of kidding relative to the 4 weeks of the year where the highest average number of births occur. Incidences of PPG that occurred during the first lactation were used as cases, while goats with none were assigned as controls. Relevant fixed and random effects were fitted in the models. In line with other reproduction traits, heritability estimates were low ranging from 0.08 to 0.11. A negative genetic correlation was found between AFK and MY520 (−0.22±0.10), whereas a positive genetic correlation was found between PPG and DIMLife (0.58±0.11). Pseudopregnancy and OOS were positively genetically correlated (0.36±0.15). All other genetic correlations were very low. The results of this study indicate that selection for the reproductive traits analysed is feasible, without adversely affecting MYLife.
The focus of this article is what Anderson (2005: 72) describes as ‘another chronic puzzle in English’, the case of to-contraction. We set out to show that the extent and nature of to-contraction has not been captured by the literature to date, because researchers have been concerned with two forms which are no longer synchronic to-contractions: wanna and gonna, and have taken a syntactic or morphological approach. On the basis of new phonological data from British English varieties we argue that the reduction of /t/ in to should be taken as evidence of to-contraction. We claim that to is a phonological clitic and to-contraction is simply the incorporation of the clitic to into the preceding prosodic word.
Mental disorders are widely recognized to be associated with increased risk of all-cause mortality. However, the extent to which highest-risk groups for mortality overlap with those viewed with highest concern by mental health services is less clear. The aim of the study was to investigate clinical risk assessment ratings for suicide, violence and self-neglect in relation to all-cause mortality among people receiving secondary mental healthcare.
A total of 9234 subjects over the age of 15 years were identified from the South London and Maudsley Biomedical Research Centre Case Register who had received a second tier structured risk assessment in the course of their clinical care. A cohort analysis was carried out. Total scores for three risk assessment clusters (suicide, violence and self-neglect) were calculated and Cox regression models used to assess survival from first assessment.
A total of 234 deaths had occurred over an average 9.4-month follow-up period. Mortality was relatively high for the cohort overall in relation to national norms [standardized mortality ratio 3.23, 95% confidence interval (CI) 2.83–3.67] but not in relation to other mental health service users with similar diagnoses. Only the score for the self-neglect cluster predicted mortality [hazard ratio (HR) per unit increase 1.14, 95% CI 1.04–1.24] with null findings for assessed risk of suicide or violence (HRs per unit increase 1.00 and 1.06 respectively).
Level of clinician-appraised risk of self-neglect, but not of suicide or violence, predicted all-cause mortality among people receiving specific assessment of risk in a secondary mental health service.
National Synchrotron Light Source (NSLS-II) is a new 3 GeV, 500 mA, high-brightness synchrotron light source facility being built at the Brookhaven National Laboratory. Approved for construction in January 2009, the NSLS-II project is expected to be completed in June 2014. In this paper we discuss the present status of the mechanical design and construction of some major components of this facility, namely (i) conventional facilities, (ii) injector complex (iii) storage ring, (iv) RF system and (v) beamlines.
The absence of I amn't for the first person singular present tense negative form is taken to indicate that there is a gap in the paradigm. Recent accounts take a morphosyntactic approach and phonology is largely ignored. Such accounts typically focus on contemporary forms of Standard English. This paper, in contrast, compares nineteenth-century and contemporary West Yorkshire (WY) aux+n't forms and pursues a largely phonological solution. The paper sets out to demonstrate that WY has never had a *amn't gap and that changes over the past century shed light on the *amn't gap problem. Contemporary WY is known to exhibit a phenomenon called secondary contraction, whereby shouldn't [ʃʊdʔ], for example, may be pronounced [ʃunʔ]. I argue that secondary contraction is responsible for the creation of homophones for amn't and aren't: [aːnt]/[aːt]. I will consider the possibility that certain aux+n't forms have become lexicalised and that this has triggered secondary contraction as a phonological repair strategy. With the analysis of WY data as a backdrop, the paper then pursues the possibility that lexicalisation may have occurred, at a much earlier date, in precursors of Standard British English (SBE). Indeed, it seems plausible that homophony for amn't and aren't may have led to prescription against new realisations of amn't. The paper will show that grammatically amn't has evolved in exactly the same way as other auxn't forms, and it is only commentators who have treated it differently. If this is so, the *amn't gap in SBE is man-made rather than grammatical in nature.
This article reports on the childhood origins and adult outcomes of female versus male antisocial behavior trajectories in the Dunedin longitudinal study. Four antisocial behavior trajectory groups were identified among females and males using general growth mixture modeling and included life-course persistent (LCP), adolescent-onset, childhood-limited, and low trajectory groups. During childhood, both LCP females and males were characterized by social, familial and neurodevelopmental risk factors, whereas those on the adolescent-onset pathway were not. At age 32, women and men on the LCP pathway were engaging in serious violence and experiencing significant mental health, physical health, and economic problems. Females and males on the adolescent-onset pathway were also experiencing difficulties at age 32, although to a lesser extent. Although more males than females followed the LCP trajectory, findings support similarities across gender with respect to developmental trajectories of antisocial behavior and their associated childhood origins and adult consequences. Implications for theory, research, and practice are discussed.
This article investigates t-to-r in West Yorkshire (WY) English and traces its course from a productive process in the nineteenth century to a lexically restricted fossil in contemporary WY. Nineteenth-century sources suggest that by the end of that century this process was already in decline. During the course of the twentieth century t-glottalling became a feature of the variety and so this article explores the possibility that as the frequency of use of t-glottalling increased, this would quickly overshadow t-to-r usage. Paradoxically, frequency of use is also responsible for the t-to-r phenomenon manifested today. More specifically, t-to-r remains in a small group of frequent words which are related by phonological shape. As a consequence of their frequency and shape, they have lexical strength and this is why a t-to-r fossil is maintained in WY today.
The number of cells in bovine and ovine embryos is reduced when steer serum which can generate high concentrations of ammonia in vitro is included in the culture system (Kuran et al., 1998). Moreover, production of embryos in synthetic oviduct fluid (SOF) medium supplemented with this serum causes fetal oversize (Sinclair et al., 1998). The present study investigated the effect of the same high ammonia-producing steer serum in a two-phase culture system on bovine embryo development and blastocyst cell numbers.
The experimental design was a 2 x 2 factorial with 5 replicates and involved a total of 928 bovine oocytes that were matured and fertilized in vitro (IVF = Day 0). Presumptive zygotes were cultured in SOF supplemented with 10% v/v steer serum (SOF+SS; n=461) or with amino acids plus 0.4% w/v crystalline BSA (SOFaaBSA; n=467) for an initial period of 48 h following IVF.
Puberty during performance test and the effect of reproductive maturity and performance on test on superovulatory response were investigated using Simmental heifers.
Three generations of Simmental heifers (no. = 110) were performance tested for beef characteristics between 23 and 49 weeks of age over 3 years successively. Embryo recoveries were performed at 52 and 61 weeks of age following the end of the performance test. The onset of puberty was observed in 26 of 30 (87%) heifers in the 3rd year. The mean age at puberty was 284·7 (s.e. 6·63) days. Age at puberty was not significantly related to daily live-weight gain (1·5 (s.e. 0·02) kg) up to the onset of puberty. Heifers experienced zero to six oestrous cycles before initiation of the first superovulatory treatments. There was a non-significant tendency (P > 0·05) for heifers that were not cyclic to produce the highest yields of viable and grade 1 embryos at the first embryo recovery.
Performance test characteristics recorded were: total food intake (1604·0 (s.e. 13·2) kg), total energy intake (1852·0 (s.e. 169·0) MJ metabolizable energy) and live-weight gain (263·9 (s.e. 2·2) kg) during test; live weight (486·5 (s.e. 31·5) kg), backfat depth (5·6 (s.e. 15) mm) and muscle score (9·6 (s.e. 0·10) units) at the end of test and estimated breeding value for the selection index (+£7·00 (s.e. 0·76)). These were used as independent variables in general linear models to study their relationship with various measures of superovulatory response. Recovery rate of ova and embryos; and the yields of viable and grade 1 embryos were not related to any aspects of performance on test.
In conclusion, superovulation and embryo recovery were affected by reproductive maturity at the time of gonadotropin treatment and these procedures may be more effective in juvenile heifers before the establishment of cyclicity. Embryo production from 12- to 15-month-old Simmental heifers following a beef performance test was not related to their performance on test.
Data from two experiments are reported which test the hypothesis that nutrient and/or dry-matter intake and body condition may interact to modify hypothalamic opioidergic activity and thus influence the pulsatile release of LH during the early post-partum period and during the oestrous cycle. Experiment 1 involved 16 multiparous, twin-suckling beef cows, and was a 2 × 2 × 2 factorial design in which the factors were level of post-partum energy intake (80 v. 130 M) metabolizable energy (ME) per day), the digestible undegradable protein (DUP) content of the post-partum diet (14 v. 31 g/kg dry matter), and treatment with either 200 mg or 400 mg naloxone hydrochloride. Blood samples were collected at 15-min intervals for 4h at weeks 4 and 7 post partum. Naloxone was administered intravenously after the eighth sample. Experiment 2 involved 16 cyclic maiden heifers and was also arranged in a factorial manner, with two levels of body condition at the start of the experimental period (2·50 and 3·16 units) and two levels of energy intake thereafter (40 and 80 MJ ME per day). Seven blood samples were collected at 15-min intervals on 4 days consecutively during the mid-luteal phase of the oestrous cycle. On the first 2 of these 4 days naloxone was administered, whilst on the last 2 days a gonadotropin-releasing hormone agonist (buserelin; GnRH) was administered, both after the fourth sample. Plasma from both experiments was assayed for LH and prolactin (Prl).
In experiment 1, cows on 130 MJ ME per day returned to oestrus and ovulated earlier than cows on 80 MJ ME per day (44·5 v. 55·0 days; s.e.d. = 3·93; P < 0·05). At week 4 post partum the proportional increase in plasma LH following naloxone challenge was greater for cows on 130 MJ ME per day than cows on 80 MJ ME per day (1·38 v. 1·12; P < 0·05), but the converse was true at week 7 (1·15 v. 1·68; P < 0·05). Cows on the high DUP diet required a higher dose of naloxone to elicit an LH response. Few heifers in experiment 2 exhibited an LH response to naloxone. In contrast, there were significant dietary treatment effects on the LH response to GnRH (P < 0·01). Relatively thin heifers on 40 MJ ME per day exhibited the lowest proportional increases in plasma LH to GnRH challenge, whereas heifers on 80 MJ ME per day and given the higher dose of GnRH produced the greatest plasma LH responses. Mean Prl concentrations before and after feeding in experiment 2 were respectively 13·2 and 10·2 ng/l (P < 0·01).
Suckled cows given a high energy diet during the early post-partum period can overcome the opioid mediated block on LH release and resume oestrous cycles earlier than cows given a low energy diet. LH would appear to be inhibited by a non-opioid mechanism in mid-luteal phase heifers. Total pituitary reserves ofLH may be influenced by the animals nutritional status.
Current variability in superovulatory response prevents the economical production of large numbers of high quality embryos and limits the use of embryo transfer. Pulsatile administration of GnRH (gonadotrophin releasing hormone) elicits pulsatile secretion of LH (luteinising hormone) while chronic treatment with a potent GnRH agonist reduces LH secretion. Using the latter, gonadotrophin-dependent preovulatory antral follicle development may be suppressed, resulting in a uniform cohort of small antral follicles in the absence of a dominant follicle which could then be superstimulated by exogenous gonadotrophin.