Antigenic distance between primary and secondary dengue infections correlates with disease risk

Many pathogens continuously change their protein structure in response to immune-driven selection, resulting in weakened protection even in previously exposed individuals. In addition, for some pathogens, such as dengue virus, poorly targeted immunity is associated with increased risk of severe disease through a mechanism known as antibody-dependent enhancement. However, it remains unclear whether the antigenic distances between an individual's first infection and subsequent exposures dictate disease risk, explaining the observed large-scale differences in dengue hospitalizations across years. Here, we develop a framework that combines detailed antigenic and genetic characterization of viruses with details on hospitalized cases from 21 years of dengue surveillance in Bangkok, Thailand, to identify the role of the antigenic profile of circulating viruses in determining disease risk. We found that the risk of hospitalization depended on both the specific order of infecting serotypes and the antigenic distance between an individual's primary and secondary infections, with risk maximized at intermediate antigenic distances. These findings suggest that immune imprinting helps determine dengue disease risk and provide a pathway to monitor the changing risk profile of populations and to quantifying risk profiles of candidate vaccines.

Unique territorial and sub-chromosomal organization revealed in the holocentric moth Bombyx mori

The hallmarks of chromosome organization in multicellular eukaryotes are chromosome territories (CT), chromatin compartments, and different types of domains, including topologically associated domains (TADs). Yet, most of these concepts derive from analyses of organisms with monocentric chromosomes. Here we describe the 3D genome architecture of an organism with holocentric chromosomes, the silkworm Bombyx mori . At the genome-wide scale, B. mori chromosomes form highly separated territories and lack substantial trans contacts. As described in other eukaryotes, B. mori chromosomes segregate into an active A and an inactive B compartment. Remarkably, we also identify a third compartment, Secluded "S", with a unique contact pattern. Compartment S shows strong enrichment of short-range contacts and depletion of long-range contacts. It hosts a unique combination of genetic and epigenetic features, localizes at the periphery of CTs and shows developmental plasticity. Biophysical modeling shows that formation of such secluded domains requires a new mechanism - a high density of extruded loops within them along with low level of extrusion and compartmentalization of A and B. Together with other evidence of loop extrusion in interphase, this suggests SMC-mediated loop extrusion in this insect. Overall, our analyses highlight the evolutionary plasticity of 3D genome organization driven by a new combination of known processes.

Antigenic diversity and dengue disease risk

Many pathogens continuously change their protein structure in response to immune-driven selection, resulting in weakened protection. In addition, for some pathogens such as dengue virus, poorly targeted immunity is associated with increased risk of severe disease, through a mechanism known as antibody-dependent enhancement. However, it remains a mystery whether the antigenic distance between an individual's first infection and subsequent exposures dictate disease risk, explaining the observed large-scale differences in dengue hospitalisations across years. Here we develop an inferential framework that combines detailed antigenic and genetic characterisation of viruses, and hospitalised cases from 21 years of surveillance in Bangkok, Thailand to identify the role of the antigenic profile of circulating viruses in determining disease risk. We find that the risk of hospitalisation depends on both the specific order of infecting serotypes and the antigenic distance between an individual's primary and secondary infections, with risk maximised at intermediate antigenic distances. These findings suggest immune imprinting helps determine dengue disease risk, and provides a pathway to monitor the changing risk profile of populations and to quantifying risk profiles of candidate vaccines.

Prevalence and Risk Factors of Secondary Hyperparathyroidism among CKD Patients and Correlation with Different Laboratory Parameters

Hyperthyroidism is one of the major complications in CKD patients who results in a number of metabolic disorders and contributes to morbidity and mortality. The objective of the study was to investigate the prevalence and risk factors for secondary hyperparathyroidism among CKD patients as well as its correlation with different laboratory parameters. This was a cross-sectional study conducted among the admitted CKD patients of Sylhet MAG Osmani Medical College Hospital, Sylhet, Bangladesh from January 2019 to December 2019. Following recruitment, clinical parameters were extracted from the patients' medical records. Afterward, blood sample blood was collected to measure the biochemical parameters and serum parathyroid hormone levels. A binary logistic regression model was used to assess the factors associated with hyperparathyroidism. The mean±SD serum PTH in all CKD patients was 215.04±168.15 pg/ml. The overall prevalence of secondary hyperparathyroidism among CKD patients was 75.0% (32.0% in stage 3, 88.0% in stage 4 and 93.0% in stage 5 CKD). Serum PTH levels had a significant positive correlation with serum creatinine and serum phosphate levels and a significant negative correlation with serum albumin and serum calcium levels. However, only female sex was revealed as a significant risk factor in the adjusted regression model (aOR 0.26, 95% CI 0.07-0.98 for male sex compared to female sex). As the prevalence of secondary hyperparathyroidism increases in advanced stages of CKD, early detection and management of CKD are crucial to prevent metabolic disorders that could trigger the development of this complication.

Beneath the surface: Amino acid variation underlying two decades of dengue virus antigenic dynamics in Bangkok, Thailand

Neutralizing antibodies are important correlates of protection against dengue. Yet, determinants of variation in neutralization across strains within the four dengue virus serotypes (DENV1-4) is imperfectly understood. Studies focus on structural DENV proteins, especially the envelope (E), the primary target of anti-DENV antibodies. Although changes in immune recognition (antigenicity) are often attributed to variation in epitope residues, viral processes influencing conformation and epitope accessibility also affect neutralizability, suggesting possible modulating roles of nonstructural proteins. We estimated effects of residue changes in all 10 DENV proteins on antigenic distances between 348 DENV collected from individuals living in Bangkok, Thailand (1994-2014). Antigenic distances were derived from response of each virus to a panel of twenty non-human primate antisera. Across 100 estimations, excluding 10% of virus pairs each time, 77 of 295 positions with residue variability in E consistently conferred antigenic effects; 52 were within ±3 sites of known binding sites of neutralizing human monoclonal antibodies, exceeding expectations from random assignments of effects to sites (p = 0.037). Effects were also identified for 16 sites on the stem/anchor of E which were only recently shown to become exposed under physiological conditions. For all proteins, except nonstructural protein 2A (NS2A), root-mean-squared-error (RMSE) in predicting distances between pairs held out in each estimation did not outperform sequences of equal length derived from all proteins or E, suggesting that antigenic signals present were likely through linkage with E. Adjusted for E, we identified 62/219 sites embedding the excess signals in NS2A. Concatenating these sites to E additionally explained 3.4% to 4.0% of observed variance in antigenic distances compared to E alone (50.5% to 50.8%); RMSE outperformed concatenating E with sites from any protein of the virus (ΔRMSE, 95%IQR: 0.01, 0.05). Our results support examining antigenic determinants beyond the DENV surface.

Dengue viruses, even of the same serotype, are differentially recognized by preexisting antibodies of individuals. With antibody levels being an important indicator of infection risk and pathogenicity, understanding mechanisms underlying these differences are crucial for vaccine design and development. Investigations have primarily targeted surface regions of the envelope protein (E) where virus-antibody interactions were thought to primarily occur. However, the roles of non-surface regions of the E protein as well as nonstructural proteins has been limited. We looked at the entire virus to identify associations between specific changes in the protein sequence and differences in how viruses were recognized by antibodies. In addition to recovering known determinants on the surface, we found signals in other areas on the structural building blocks of the virus. We also identified additional signals on specific areas of a protein that does not form structures of the virus but orchestrate virus formation. Our results point towards broadening the frame of investigation to gain a more comprehensive understanding of mechanisms giving rise to antibody recognition of dengue viruses, and may aid the design and evaluation of vaccines and/or assays to characterize dengue immunity.

Disseminated Intravascular Coagulation in Varying Age Groups Based on Clinical Conditions

Disseminated intravascular coagulation (DIC) is a serious syndrome characterized by the systemic activation of blood coagulation resulting in the thrombosis of vessels leading to organ dysfunction and severe bleeding. When physicians try to treat DIC, it is imperative to diagnose and treat the underlying conditions. Anyone can be affected by DIC, but vulnerable groups such as pediatric populations, pregnant women and the elderly may be at higher risk. In this review, the current literature on DIC in pregnancy, the pediatric population, and the elderly is reported. This review also highlights the similarities and differences in the etiology, clinical presentation, diagnosis, and management of DIC in the aforementioned groups (i.e., pediatrics, pregnant women, and the elderly). Findings from this study may help increase awareness about various presentations of DIC in these groups to facilitate rapid recognition of symptoms leading to correct diagnoses.

Antigenic evolution of dengue viruses over 20 years

Infection with one of dengue viruses 1 to 4 (DENV1-4) induces protective antibodies against homotypic infection. However, a notable feature of dengue viruses is the ability to use preexisting heterotypic antibodies to infect Fcγ receptor–bearing immune cells, leading to higher viral load and immunopathological events that augment disease. We tracked the antigenic dynamics of each DENV serotype by using 1944 sequenced isolates from Bangkok, Thailand, between 1994 and 2014 (348 strains), in comparison with regional and global DENV antigenic diversity (64 strains). Over the course of 20 years, the Thailand DENV serotypes gradually evolved away from one another. However, for brief periods, the serotypes increased in similarity, with corresponding changes in epidemic magnitude. Antigenic evolution within a genotype involved a trade-off between two types of antigenic change (within-serotype and between-serotype), whereas genotype replacement resulted in antigenic change away from all serotypes. These findings provide insights into theorized dynamics in antigenic evolution.

Congenital Eventration of Diaphragm Presenting As Diaphragmatic Hernia: A Case Report

Eventration of diaphragm is an abnormal elevation of diaphragmatic musculature while retaining normal attachments to the sternum, ribs and dorsolumber spine. It is a rare anomaly where the continuity of diaphragm remains intact. Pathological process can affect either all or only a portion of hemidiaphragm. Symptoms vary according to size of the defect. Large defect may mimic diaphragmatic hernia. The present case represents a full term female newborn that developed respiratory distress, cyanosis and feeding difficulties since 1st day of life. Clinical features and chest imaging of this case was assumed to be left sided diaphragmatic hernia which was found wrong in the operation theater. She was found to have left sided eventration of diaphragm to create symptom. Successful plication of ipsilateral diaphragm was done on 13th day of life. Supervised post operative ventilatory support along with other postoperative care improved the condition of this neonate. A large defect with eventration of diaphragm may be life threatening but a timely good management can save neonate from such condition.

Predicting depressed patients with suicidal ideation from ECG recordings

Globally suicidal behavior is the third most common cause of death among patients with major depressive disorder (MDD). This study presents multi-lag tone-entropy (T-E) analysis of heart rate variability (HRV) as a screening tool for identifying MDD patients with suicidal ideation. Sixty-one ECG recordings (10 min) were acquired and analyzed from control subjects (29 CONT), 16 MDD subjects with (MDDSI+) and 16 without suicidal ideation (MDDSI-). After ECG preprocessing, tone and entropy values were calculated for multiple lags (m: 1-10). The MDDSI+ group was found to have a higher mean tone value compared to that of the MDDSI- group for lags 1-8, whereas the mean entropy value was lower in MDDSI+ than that in CONT group at all lags (1-10). Leave-one-out cross-validation tests, using a classification and regression tree (CART), obtained 94.83 % accuracy in predicting MDDSI+ subjects by using a combination of tone and entropy values at all lags and including demographic factors (age, BMI and waist circumference) compared to results with time and frequency domain HRV analysis. The results of this pilot study demonstrate the usefulness of multi-lag T-E analysis in identifying MDD patients with suicidal ideation and highlight the change in autonomic nervous system modulation of the heart rate associated with depression and suicidal ideation.

Identifying depressed patients with and without suicidal ideation by finger photo-plethysmography

Major Depressive Disorder (MDD) is a serious mental disorder that if untreated not only affects physical health but also has a high risk of suicide. While the neurophysiological phenomena that contribute to the formation of Suicidal Ideation (SI) are still ill-defined, clear links between MDD and cardiovascular disease have been reported. The aim of this study is to extract suitable features from arterial pulse signals with a view to predicting SI within MDD and control groups. Sixteen unmedicated MDD patients with a history of SI (MDDSI+), sixteen without SI (MDDSI-) and twenty-nine healthy subjects (CONT) were recruited at a psychiatric clinic in the UAE. Depression severity and SI were assessed using the Hamilton Depression Rating Scale and Beck Depression Inventory. Pulse Wave Amplitude (PWA) was calculated as the difference between the peak (Systole) and the valley (Diastole) of the arterial pulse within each cardiac cycle. Then, 2D Tone-Entropy (TE) features were extracted from the Systole, Diastole and PWA time series. The TE features extracted from Diastole were the best markers for predicting MDDSI+. The overall classification accuracies of Classification and Regression Tree (CART) model by using TE features of Systole, Diastole and PWA were 88.52%, 90.2% and 88.52% respectively. When all TE features were combined, accuracy increased up to 93.44% in identifying MDDSI+/MDDSI-/Control groups.

Identification of a novel class of covalent modifiers of hemoglobin as potential antisickling agents

Aromatic aldehydes and ethacrynic acid (ECA) exhibit antipolymerization properties that are beneficial for sickle cell disease therapy. Based on the ECA pharmacophore and its atomic interaction with hemoglobin, we designed and synthesized several compounds - designated as KAUS (imidazolylacryloyl derivatives) - that we hypothesized would bind covalently to βCys93 of hemoglobin and inhibit sickling. The compounds surprisingly showed weak allosteric and antisickling properties. X-ray studies of hemoglobin in complex with representative KAUS compounds revealed an unanticipated mode of Michael addition between the β-unsaturated carbon and the N-terminal αVal1 nitrogen at the α-cleft of hemoglobin, with no observable interaction with βCys93. Interestingly, the compounds exhibited almost no reactivity with the free amino acids, L-Val, L-His and L-Lys, but showed some reactivity with both glutathione and L-Cys. Our findings provide a molecular level explanation for the compounds biological activities and an important framework for targeted modifications that would yield novel potent antisickling agents.

Birth prevalence of congenital cytomegalovirus among infants of HIV-infected women on prenatal antiretroviral prophylaxis in South Africa

BACKGROUND

A high rate of congenital cytomegalovirus (CMV) has been documented in human immunodeficiency virus (HIV)-exposed infants in industrialized settings, both in the pre- and post-highly active antiretroviral therapy (HAART) era. Only limited data on the birth prevalence of congenital CMV among infants of HIV-infected women on prenatal antiretroviral (ARV) prophylaxis are available from sub-Saharan Africa, despite a high prevalence of both infections. We evaluated the prevalence of congenital CMV in HIV-exposed infants in the Western Cape, South Africa.

METHODS

HIV-infected mothers were recruited in the immediate postnatal period at a referral maternity hospital between April and October 2012. Maternal and infant clinical data and newborn saliva swabs were collected. Saliva swabs were assayed by real-time polymerase chain reaction for CMV. Data were analyzed using univariate and multivariate logistic regression analyses to determine specific demographic, maternal, and newborn characteristics associated with congenital CMV.

RESULTS

CMV was detected in 22 of 748 newborn saliva swabs (2.9%; 95% confidence interval [CI], 1.9%-4.4%). Overall, 96% of mothers used prenatal ARV prophylaxis (prenatal zidovudine, 43.9%; HAART, 52.1%). Maternal age, gestational age, prematurity (<37 weeks' gestation), type of ARV prophylaxis, length of ARV prophylaxis, birth weight, small for gestational age, and infant feeding choice were not significantly different between CMV-infected and -uninfected infants. Maternal CD4 count <200 cells/μL during pregnancy was independently associated with congenital CMV (adjusted odds ratio, 2.9; 95% CI, 1.2-7.3). A negative correlation between CMV load in saliva and maternal CD4 count was observed (r = -0.495, n = 22, P = .019).

CONCLUSIONS

The birth prevalence of congenital CMV was high despite prenatal ARV prophylaxis, and was associated with advanced maternal immunosuppression.

Comparison of modified Friedewald's formula with direct measurement of low-density lipoprotein cholesterol in Bangladeshi population

A modification of Friedewald's formula to estimate serum low-density lipoprotein cholesterol (LDLC) up to serum triglyceride (TG) level of 11.3 mmol/L in Bangladeshi population has recently been published. The aim of this study was to compare the modified formula with direct measurement of LDLC in Bangladeshi population in a different setting. One thousand and fifty two specimens from adult subjects were analyzed. Serum total cholesterol (TC), high-density lipoprotein cholesterol (HDLC), LDLC and TG were measured by standard methods. The modified Friedewald's formula was applied to estimate LDL cholesterol concentration. Results were expressed as mean ± SD and calculated LDLC was compared with measured LDLC by two-tailed paired t test, Bland-Altman plot for absolute bias, Pearson's correlation coefficients of calculated LDLC with measured LDLC and Passing & Bablok regression equation of calculated LDLC against measured LDLC. The mean ± SD of measured LDLC was 2.98 ± 0.82 mmol/L. LDLC calculated by modified Friedewald's formula was 2.77 ± 0.86 mmol/L. The mean absolute bias was -0.20 ± 0.32 mmol/L, Pearson's correlation coefficient (r) was 0.9293 (P < 0.0001) and Passing & Bablok regression equation was y = - 0.3856+1.0597x for modified formula up to serum TG ≤ 11.3 mmol/L. Compared to original Friedewald's formula, performance of the modified Friedewald's formula was better up to serum TG ≤ 4.52 mmol/L. The study reveals that the modified Friedewald's formula may be used to calculate LDLC approximately in Bangladeshi population.

Redox metabolism abnormalities in autistic children associated with mitochondrial disease

Research studies have uncovered several metabolic abnormalities associated with autism spectrum disorder (ASD), including mitochondrial disease (MD) and abnormal redox metabolism. Despite the close connection between mitochondrial dysfunction and oxidative stress, the relation between MD and oxidative stress in children with ASD has not been studied. Plasma markers of oxidative stress and measures of cognitive and language development and ASD behavior were obtained from 18 children diagnosed with ASD who met criteria for probable or definite MD per the Morava et al. criteria (ASD/MD) and 18 age and gender-matched ASD children without any biological markers or symptoms of MD (ASD/NoMD). Plasma measures of redox metabolism included reduced free glutathione (fGSH), oxidized glutathione (GSSG), the fGSH/GSSG ratio and 3-nitrotyrosine (3NT). In addition, a plasma measure of chronic immune activation, 3-chlorotyrosine (3CT), was also measured. Language was measured using the preschool language scale or the expressive one-word vocabulary test (depending on the age), adaptive behaviour was measured using the Vineland Adaptive Behavior Scale (VABS) and core autism symptoms were measured using the Autism Symptoms Questionnaire and the Social Responsiveness Scale. Children with ASD/MD were found to have lower scores on the communication and daily living skill subscales of the VABS despite having similar language and ASD symptoms. Children with ASD/MD demonstrated significantly higher levels of fGSH/GSSG and lower levels of GSSG as compared with children with ASD/NoMD, suggesting an overall more favourable glutathione redox status in the ASD/MD group. However, compare with controls, both ASD groups demonstrated lower fGSH and fGSH/GSSG, demonstrating that both groups suffer from redox abnormalities. Younger ASD/MD children had higher levels of 3CT than younger ASD/NoMD children because of an age-related effect in the ASD/MD group. Both ASD groups demonstrated significantly higher 3CT levels than control subjects, suggesting that chronic inflammation was present in both groups of children with ASD. Interestingly, 3NT was found to correlate positively with several measures of cognitive function, development and behavior for the ASD/MD group, but not the ASD/NoMD group, such that higher 3NT concentrations were associated with more favourable adaptive behaviour, language and ASD-related behavior. To determine whether difference in receiving medications and/or supplements could account for the differences in redox and inflammatory biomarkers across ASD groups, we examined differences in medication and supplements across groups and their effect of redox and inflammatory biomarkers. Overall, significantly more participants in the ASD/MD group were receiving folate, vitamin B12, carnitine, co-enzyme Q10, B vitamins and antioxidants. We then determined whether folate, carnitine, co-enzyme Q10, B vitamins and/or antioxidants influenced redox or inflammatory biomarkers. Antioxidant supplementation was associated with a significantly lower GSSG, whereas antioxidants, co-enzyme Q10 and B vitamins were associated with a higher fGSH/GSSG ratio. There was no relation between folate, carnitine, co-enzyme Q10, B vitamins and antioxidants with 3NT, 3CT or fGSH. Overall, our findings suggest that ASD/MD children with a more chronic oxidized microenvironment have better development. We interpret this finding in light of the fact that more active mitochondrial can create a greater oxidized microenvironment especially when dysfunctional. Thus, compensatory upregulation of mitochondria which are dysfunctional may both increase activity and function at the expense of a more oxidized microenvironment. Although more ASD/MD children were receiving certain supplements, the use of such supplements were not found to be related to the redox biomarkers that were related to cognitive development or behavior in the ASD/MD group but could possibly account for the difference in glutathione metabolism noted between groups. This study suggests that different subgroups of children with ASD have different redox abnormalities, which may arise from different sources. A better understanding of the relationship between mitochondrial dysfunction in ASD and oxidative stress, along with other factors that may contribute to oxidative stress, will be critical to understanding how to guide treatment and management of ASD children. This study also suggests that it is important to identify ASD/MD children as they may respond differently to specific treatments because of their specific metabolic profile.

Metabolic effects of sapropterin treatment in autism spectrum disorder: a preliminary study

Sapropterin, a synthetic form of tetrahydrobiopterin (BH4), has been reported to improve symptoms in children with autism spectrum disorder (ASD). However, as BH4 is involved in multiple metabolic pathway that have been found to be dysregulated in ASD, including redox, pterin, monoamine neurotransmitter, nitric oxide (NO) and immune metabolism, the metabolic pathway by which sapropterin exerts its therapeutic effect in ASD effect remains unclear. This study investigated which metabolic pathways were associated with symptomatic improvement during sapropterin treatment. Ten participants (ages 2-6 years old) with current social and/or language delays, ASD and a central BH4 concentration 30 nM l(-1) were treated with a daily morning 20 mg kg(-1) dose of sapropterin for 16 weeks in an open-label fashion. At baseline, 8 weeks and 16 weeks after starting the treatment, measures of language, social function and behavior and biomarkers of redox, pterin, monoamine neurotransmitter, NO and immune metabolism were obtained. Two participants discontinued the study, one from mild adverse effects and another due to noncompliance. Overall, improvements in subscales of the Preschool Language Scale (PLS), Vineland Adaptive Behavior Scale (VABS), Aberrant Behavior Checklist (ABC) and autism symptoms questionnaire (ASQ) were seen. Significant changes in biomarkers of pterin, redox and NO were found. Improvement on several subscales of the PLS, VABS, ABC and ASQ were moderated by baseline and changes in biomarkers of NO and pterin metabolism, particularly baseline NO metabolism. These data suggest that behavioral improvement associated with daily 20 mg kg(-1) sapropterin treatment may involve NO metabolism, particularly the status of pretreatment NO metabolism.

Generational differences in factors influencing physicians to choose a work location

INTRODUCTION

Canadian medical schools have increased enrolment and recruited more rural students in an effort to address general and rural physician shortages. The success of this approach depends on the recruitment of these newly trained physicians to under-serviced areas. Studies from North America suggest that the career expectations and practice patterns of younger, more recently graduated physicians differ from those of their older counterparts. This study explored the factors that influenced the work location choices of physicians of differing generations, who trained at universities in Saskatchewan, and Newfoundland and Labrador, two Canadian provinces with large rural populations and no community larger than 235 000 population.

METHODS

Semi-structured, qualitative interviews were conducted with physicians who graduated from either the Memorial University of Newfoundland or the University of Saskatchewan. Generation definitions were based on the graduation year. Early-career physicians graduated between 1995 and 1999; mid-career physician graduated between 1985 and 1989; late-career physicians graduated between 1975 and 1979; and end-career physicians graduated between 1965 and 1969. Each physician was asked questions about the number and nature of work location changes over the course of their careers and the factors related to their decision to choose each location. Interview transcripts and notes were analyzed using a thematic analysis approach. Although the study focus was on generational differences, similarities and differences between universities, sexes and specialties (family physicians/GPs vs specialists) were also examined. Recruitment to the provinces was focused on as a whole, because the largest communities in the provinces are small compared with most urban communities.

RESULTS

Forty-eight physicians were interviewed, five to nine physicians who graduated in each decade and from each university. The desire to be near family and friends was cited as the primary consideration when choosing a work location, regardless of generation. Likewise, residency training location, the ability to use their skills and knowledge fully, and the quality of recruitment efforts were important considerations in choosing a work location for all physicians. For some, remuneration was very influential in their work location decision; however, many physicians who chose to remain in their smaller 'home' provinces noted the lower cost of living in these provinces. Physicians who graduated in the 1980s and 1990s placed greater emphasis on work-life balance and spouse's employment opportunities than their older generation counterparts. In contrast, physicians who graduated in the 1960s and 1070s highlighted the medical need of the community, and the desire for adventure and to see new places as important.

CONCLUSIONS

While many factors for choosing a work location appear to be stable over generations, a number of generational differences were found. Younger physicians placed greater emphasis on work-life balance and spouse's employment than older generation physicians. These differences may have important implications for small population regions which may not be able to support physician-spouse pairs or certain subspecialties. Although economic factors have largely been the focus of recruitment and retention initiatives in these provinces, the findings highlight the importance of addressing the needs and expectations of younger generation physicians in order to attract these physicians.

Identification of Vibrio harveyi as a causative bacterium for a tail rot disease of sea bream Sparus aurata from research hatchery in Malta

A bacterial disease was reported from gilthead sea bream (Sparus aurata) within a hatchery environment in Malta. Symptoms included complete erosion of tail, infection in the eye, mucous secretion and frequent mortality. A total of 540 strains were initially isolated in marine agar from different infected body parts and culture water sources. Subsequently 100 isolates were randomly selected, identified biochemically and all were found to be Vibrio harveyi-related organisms; finally from 100 isolates a total of 13 numbers were randomly selected and accurately identified as V. harveyi by 16S rRNA gene sequencing and species-specific PCR. Ribotyping of these strains with HindIII revealed total of six clusters. In vivo challenge study with representative isolates from each cluster proved two clusters each were highly pathogenic, moderately pathogenic and non-pathogenic. All 13 isolates were positive for hemolysin gene, a potential virulence factor. Further analysis revealed probably a single copy of this gene was encoded in all isolates, although not in the same locus in the genome. Although V. harveyi was reported to be an important pathogen for many aquatic organisms, to our knowledge this might be the first report of disease caused by V. harveyi and their systematic study in the sea bream hatchery from Malta.

Simvastatin enhances hippocampal long-term potentiation in C57BL/6 mice

Statins inhibit 3-hydroxy-3-methylglutaryl CoA reductase, the rate-limiting enzyme in the cholesterol biosynthetic pathway, and they are widely used to control plasma cholesterol levels and prevent cardiovascular disease. However, emerging evidence indicates that the beneficial effects of statins extend to the CNS. Statins have been shown to improve the outcome of stroke and traumatic brain injury, and statin use has been associated with a reduced prevalence of Alzheimer's disease (AD) and dementia. However, prospective studies with statins in AD have produced mixed results. Recently, we reported that simvastatin, a widely used statin in humans, enhances learning and memory in non-transgenic mice as well as in transgenic mice with AD-like pathology on a mixed genetic background. However, the cellular and molecular mechanisms underlying the beneficial effects of simvastatin on learning and memory remain elusive. The present study was undertaken to investigate the effect of acute simvastatin treatment on hippocampal long-term potentiation (LTP), a cellular model of learning and memory, in brain slices from C57BL/6 mice. Our results demonstrate that a prolonged in vitro simvastatin treatment for 2-4 h, but not a short-term 20-min exposure, significantly increases the magnitude of LTP at CA3-CA1 synapses without altering basal synaptic transmission or the paired-pulse facilitation ratio in hippocampal slices. Furthermore, we show that phosphorylation of Akt (protein kinase B) is increased significantly in the CA1 region following 2-hour treatment with simvastatin, and that inhibition of Akt phosphorylation suppresses the simvastatin-induced enhancement of LTP. These findings suggest activation of Akt as a molecular pathway for augmented hippocampal LTP by simvastatin treatment, and implicate enhancement of hippocampal LTP as a potential cellular mechanism underlying the beneficial effects of simvastatin on cognitive function.

Pregnancy trends after abortion

A series of women who aborted their pregnancies at King Khalid University Hospital (KKUH), Riyadh, Saudi Arabia, over a period of 12 months (1 January 1992 to 3 December 1992), were followed up for 6-48 months afterwards to examine their pregnancy trends. Descriptive statistics for data presentation with Kaplan-Meier survivorship function estimates time from abortion to the next pregnancy and Cox proportional hazard regression analysis were used to identify prognostic factors. Eighty-one per cent of the women achieved pregnancy over a 4-year follow-up. The median time to pregnancy was 7.6 months, with a 95% confidence interval of 6.4-10.0 months. Age and nationality were found to be significant prognostic factors related to time to achieve a pregnancy. Furthermore, the outcome of the subsequent pregnancy was found to be statistically related to the number of previous abortions. There is a high chance of fertility after an abortion, with 75.2% of these occurring within the first 12 months of the post-abortion follow-up period and dwindling to only 4.1% by the end of 36 months. Using multivariate regression analysis, only age seemed to be an important determinant factor.

137Cs-uptake into wheat (Triticum vulgare) plants from five representative soils of Bangladesh

A pot experiment was conducted to study the uptake of 137Cs by wheat grown in five representative soils of Bangladesh having different soil characteristics. Artificial application of 137Cs increased the activity in soils up to 45.9 Bq/kg soil, measured at the end of the harvest of wheat crop. Different plant parts had different ability to accumulate 137Cs. Grains had the least activity and transfer factor, while the highest activity and lowest transfer factor were measured in roots, which restricted translocation of 137Cs to wheat straw. The result showed that the transfer factors (mean value) varied from 0.05 to 0.114 in wheat straw, 0.066-0.133 in roots and 0.011-0.043 in wheat grains. The activity and transfer factor of radioactive cesium in wheat plants were found to be greatly influenced by soil properties, i.e. clay content, K, organic matter, CEC, pH, exchangeable ions, etc. Cation exchange capacity and calcium in soils influenced positively, while clay minerals, exchangeable K and organic matter, negatively affected the 137Cs activity concentrations in wheat plants.

Socio-demographic characteristics of the "unbooked mother"

In a study to investigate the characteristics of the "Unbooked mother", the medical records of 467 patients who presented for delivery with no prenatal care at the obstetric unit of the King Khalid University Hospital (KKUH), Riyadh, during the period 1991 to 1995 were evaluated. For controls, the records of 415 mothers who had pre-natal care in the Unit over the same period were also evaluated. Data pertaining to their socio-demographic characteristics, previous obstetric history, prevalence of pregnancy-related and familial diseases, gestation age at delivery and weights of the babies, were extracted and analysed using odds ratios and 95% confidence intervals (C.I.). The unbooked mother tended to be young (< or = 24 years), unskilled worker, or student. On the other hand, the booked ones tended to be primigravid, with pregnancy-related (PET) and familial diseases (hypertension and diabetes). However, the level of parity, gestation age and birth weights did not appear to significantly influence the tendency to be booked or unbooked. These findings highlight the group of women who should be targeted for health education counselling regarding the value of prenatal care. This way, one can avoid some of the catastrophes often said to be associated with deliveries in the unbooked mother.

Demographic and fertility variables as determinants of spontaneous abortions in women with previous abortions

The objective of the study was to examine the demographic and fertility factors that may predispose to spontaneous abortion in women with prior abortion. The study was conducted in King Khalid University Hospital, Riyadh, Saudi Arabia. It included a series of women who aborted their pregnancies over a period of months (January 1; 1992-December 31, 1992). Chi-square and Fisher's exact test were used to analyze the statistical relationship between abortion and various demographic and fertility, related to abortion. There was a direct statistically significant relationship between maternal age, level of education, parity and a history of previous abortion. In a multivariate logistic regression analysis, parity and history of previous abortion were found to be significant as determinants of recurrent abortion. Even though many of these risk factors are not preventable, counseling of the women about the value of education, early reproduction in the child-bearing age, and control of fertility would go a long way in reducing the incidence of fetal wastage in these women.

Obstetric outcome in the unbooked mother

This study aimed at determining the outcome of pregnancy in unbooked mothers with regard to maternal complications and foetal outcome. This retrospective study was based on investigations of medical records of 467 unbooked mothers who presented for delivery at the Obstetrics Unit at King Khalid University Hospital, Riyadh, during the period 1991 and 1992, and 415 booked mothers with regular clinic attendance selected as controls. Data collected from the records included patients' socio-demographic characteristics, past obstetric history, prevalence of pregnancy-related diseases, and data relating to labour, delivery, and foetal outcome. Chi-square test and Fisher's exact test were used for assessing the statistical significance of the association between the various factors which were investigated. The tendency for mothers to be booked was found to be significantly associated with their age, occupation, parity, and gestational age at delivery. Booked and unbooked mothers did not differ significantly in relation to the mode of delivery and foetal outcome, although the prevalence of previous complications of pregnancy was generally lower among unbooked mothers. There was no statistically significant association between the absence of antenatal care and outcome of pregnancies, unbooked mothers had a higher proportion of MICU admissions and dead babies compared with the controls. Educating the community about the benefits of receiving regular antenatal care, even if at primary care level, may be of great importance in improving the pregnancy outcome.

Risk of retained placenta: multivariate approach

BACKGROUND

To identify important covariates related to retained placenta using logistic regression analysis.

METHODS

The study was carried out in the King Khalid University Hospital, Saudi Arabia, and involved 114 women who had retained placenta, and 116 women with normal deliveries. Chi-square test and logistic regression analysis were used for analysis of data. Adequacy of predictor variables was examined using indices of sensitivity and specificity and plots of probability histograms for prediction of retained placenta among patients and controls.

RESULTS

Logistic regression analysis highlighted multiparity, induced labor, small placenta, and large amount of blood loss to be significantly associated with retained placenta. In addition, high pregnancy number, previous injury to uterus, and pre-term labor related significantly to retained placenta. Predictor variables had sensitivity of 65.5% and 87.9% specificity and achieved 77% overall correct classification.

CONCLUSIONS

These findings could be used to develop a predictive procedure for identifying high-risk cases of retained placenta.

An appraisal of the appropriateness of the indications for hysterectomy

Over a five-year period, 197 hysterectomies were performed at King Khalid University Hospital (KKUH). Indications for the procedures vary from menstrual disorders and symptomatic fibroids to ovarian malignancy. The most common indication was found to be menorrhagia. Among multiple pre-operative indications, only the first listed major indication for hysterectomy was chosen. There were 145 abdominal and 52 vaginal hysterectomies and all were elective gynaecological procedures, majority of which were performed on women in their fourth and fifth decades of life. Verification of pre-operative diagnosis, when correlated with pathological findings, showed that some of the indications for the procedure deserve a more critical reappraisal. Since hysterectomy carries substantial economic and medical consequences, indications for undertaking the procedure deserve more careful scrutiny given the surgical and nonsurgical options that are currently available. There may be a need, therefore, to assess the appropriateness or otherwise of the use of hysterectomy in many of the patients in future.

Obstetric outcome in uncomplicated prolonged pregnancy

OBJECTIVE

To study and compare the obstetric outcome in term pregnancies and uncomplicated prolonged pregnancies.

METHODS

The study was a retrospective review of 596 cases. The case notes of 286 patients with uncomplicated prolonged pregnancies (> or = 42 weeks) and 310 patients with normal term pregnancies (37 to < 42 weeks) were analyzed. The Gold Stat package was used for statistical coding and analysis.

RESULTS

There was no fetal morbidity or mortality among the two groups. However, the number of previous abortions were significantly higher in prolonged pregnancies compared with term pregnancies. Similarly, fetal and placental weights, labor induction and operative delivery rates were significantly higher in prolonged pregnancies. However, there were no significant differences between the patients who were induced and those who had spontaneous labor among the prolonged pregnancies.

CONCLUSIONS

There is no doubt that prolonged pregnancy may be associated with certain risks factors. However, there is no outcome variable to justify whether or not to induce those pregnancies which are prolonged.

Subchorionic hematoma in threatened abortion: Sonographic evaluation and significance

In a study of 92 women with subchorionic hematoma evaluated with sonographic scan in King Khalid University Hospital, it was found that the mean ages and live births of patients who carried their pregnancies to viability were higher when compared with the patients who aborted. There was a statistically significant association between the gestational age at diagnosis of subchorionic hematoma and the size of the hematoma. There was, however, no statistically significant association found between the gestational age at diagnosis, size and site of the hematoma and the outcome of pregnancy. It was concluded that subchorionic hematoma which appear either in the second trimester, or are larger, or located in the lower uterine segment, may be associated with higher rates of abortion or preterm deliveries. Nevertheless, there is no statistically significant impact of these on the outcome of pregnancy.

Outcome in elective and emergency cesarean sections: A comparative study

To study the obstetrics outcome of cesarean sections (CS) in relation to the elective or emergency nature of this procedure, a comparative study was conducted on 1426 females whose deliveries were by CS in King Khalid University Hospital (KKUH). Of the various factors analyzed in relation to the two types of CS, statistically significant associations were found between emergency CS and younger patients, low parity, irregular attendance at antenatal clinics, complications in labor, postoperative morbidity and low Apgar score(>6). It was concluded that every effort should be directed to effect-planned CS, as determined during the antenatal period, if possible, so as to reduce the various problems associated with emergency CS. The chances are that this approach is unlikely to influence the overall CS rate in either way.

Neuropeptides induce release of nitric oxide from human dermal microvascular endothelial cells

Nitric oxide is a potent mediator of endothelium-dependent vasodilation, the synthesis of which is catalyzed by the constitutively expressed enzyme endothelial nitric oxide synthase. In this study we have investigated whether human dermal microvascular endothelial cells express endothelial oxide synthase and whether the vasodilator neuropeptides, calcitonin gene-related peptide and substance P, stimulate the release of nitric oxide from these cells. Endothelial nitric oxide synthase was identified by immunohistochemistry in the blood vessels in both the papillary and deep dermis of normal skin, and also in monolayers of human dermal microvascular extracts prepared from both the dermis of normal human skin and human dermal microvascular endothelial cells, a 135-kDa band corresponding to endothelial nitric oxide synthase was identified. Nitric oxide was released from unstimulated human dermal microvascular endothelial cells as assessed by inhibition of platelet aggregation and nitrate formation. Endothelial cell-mediated inhibition of platelet aggregation was blocked by hemoglobin. Calcitonin gene-related peptide, (100 pM to 100 nM) directly inhibited platelet aggregation, and this direct effect was not modulated by microvascular endothelial cells. Substance P (10 nM to 1 muM) and calcitonin gene-related peptide (100 pM to 10 nM) significantly (p<0.05) increased nitrite formation, and this increase was blocked by the competitive nitric oxide synthase antagonist, NG-monomethyl-L-arginine. These results demonstrate that endothelial nitric oxide synthase is expressed in the microvascular endothelium of normal human skin and that human dermal microvascular endothelial cells release nitric oxide constitutively and in response to vasodilator neuropeptides.