Suboptimal breastfeeding practices are associated with infant illness in Vietnam

Background

Despite evidence supporting the importance of breastfeeding to child health, breastfeeding practices remain suboptimal in Vietnam. There is currently little evidence on the importance of breastfeeding in the prevention of morbidity during infancy in Vietnam. In order to provide country specific data for policy makers to support breastfeeding friendly policies and programs, analysis was undertaken on a cross-sectional dataset to investigate the association between breastfeeding practices and prevalence of diarrhea and acute respiratory infection (ARI) among infants aged 0–5 months.

Methods

Data on socio-demographic characteristics, infant feeding practices and prevalence of diarrhea and ARI were obtained from 6,068 mother-child dyads in 11 provinces of Vietnam in 2011. Multivariate logistic regression was used to examine the associations between breastfeeding practices and child illnesses.

Results

On average, the prevalence of diarrhea and ARI among infants 0–5 months was 5.3% and 24.5%, respectively. Though half of all infants were breastfed within one hour of birth, 73.3% were given prelacteal foods in the first three days after birth. Only 20.2% of children 0–5 months old were exclusively breastfed, while 32.4% were predominantly breastfed and 47.4% partially breastfed. After adjusting for confounders, early initiation of breastfeeding was associated with lower prevalence of diarrhea [adjusted odds ratio (AOR) = 0.74 (95% CI 0.58, 0.93)], while prelacteal feeding was associated with higher prevalence [AOR = 1.53 (95% CI 1.15, 2.03)]. Compared to infants who were exclusively breastfed, infants who were predominantly [AOR = 1.52 (95% CI 1.05, 2.21)] or partially breastfed [AOR = 1.55 (95% CI 1.07, 2.24)] were more likely to have diarrhea. Prelacteal feeding [AOR = 1.16 (95% CI 1.01, 1.33)] and partial breastfeeding [AOR relative to exclusive breastfeeding = 1.24 (95% CI 1.03, 1.48)] were associated with higher prevalence of ARI. While the protective effects of exclusive breastfeeding against diarrhea declined with child age, this effect for ARI appears to have remained constant.

Conclusions

Early initiation and exclusive breastfeeding protects against diarrhea and ARI. Results confirm that interventions to improve early and exclusive breastfeeding would contribute to improving child health and nutrition in Vietnam.

Critical temperature of interacting Bose gases in periodic potentials

The superfluid transition of a repulsive Bose gas in the presence of a sinusoidal potential which represents a simple-cubic optical lattice is investigated using quantum Monte Carlo simulations. At the average filling of one particle per well the critical temperature has a nonmonotonic dependence on the interaction strength, with an initial sharp increase and a rapid suppression at strong interactions in the vicinity of the Mott transition. In an optical lattice the positive shift of the transition is strongly enhanced compared to the homogenous gas. By varying the lattice filling we find a crossover from a regime where the optical lattice has the dominant effect to a regime where interactions dominate and the presence of the lattice potential becomes almost irrelevant.

Genome-wide analysis of rare copy number variations reveals PARK2 as a candidate gene for attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) is a common, highly heritable neurodevelopmental disorder. Genetic loci have not yet been identified by genome-wide association studies. Rare copy number variations (CNVs), such as chromosomal deletions or duplications, have been implicated in ADHD and other neurodevelopmental disorders. To identify rare (frequency ≤1%) CNVs that increase the risk of ADHD, we performed a whole-genome CNV analysis based on 489 young ADHD patients and 1285 adult population-based controls and identified one significantly associated CNV region. In tests for a global burden of large (>500 kb) rare CNVs, we observed a nonsignificant (P=0.271) 1.126-fold enriched rate of subjects carrying at least one such CNV in the group of ADHD cases. Locus-specific tests of association were used to assess if there were more rare CNVs in cases compared with controls. Detected CNVs, which were significantly enriched in the ADHD group, were validated by quantitative (q)PCR. Findings were replicated in an independent sample of 386 young patients with ADHD and 781 young population-based healthy controls. We identified rare CNVs within the parkinson protein 2 gene (PARK2) with a significantly higher prevalence in ADHD patients than in controls (P=2.8 × 10(-4) after empirical correction for genome-wide testing). In total, the PARK2 locus (chr 6: 162 659 756-162 767 019) harboured three deletions and nine duplications in the ADHD patients and two deletions and two duplications in the controls. By qPCR analysis, we validated 11 of the 12 CNVs in ADHD patients (P=1.2 × 10(-3) after empirical correction for genome-wide testing). In the replication sample, CNVs at the PARK2 locus were found in four additional ADHD patients and one additional control (P=4.3 × 10(-2)). Our results suggest that copy number variants at the PARK2 locus contribute to the genetic susceptibility of ADHD. Mutations and CNVs in PARK2 are known to be associated with Parkinson disease.

Prelacteal feeding practices in Vietnam: challenges and associated factors

BACKGROUND

Despite the importance of early initiation of and exclusive breastfeeding, prelacteal feeds continue to pose a barrier to optimal breastfeeding practices in several countries, including Vietnam. This study examined the factors associated with prelacteal feeding among Vietnamese mothers.

METHODS

Data from 6068 mother-child (<6 m) dyads were obtained from a cross-sectional survey conducted in 11 provinces in Vietnam in 2011. Multivariate logistic regression analyses were used to examine factors associated with prelacteal feeding.

RESULTS

During the first three days after birth, 73.3% of the newborns were fed prelacteals, 53.5% were fed infants formula, and 44.1% were fed water. The odds of feeding prelacteals declined with increased breastfeeding knowledge, beliefs about social norms in favor of exclusive breastfeeding, and confidence in one's own breastfeeding behaviors. Women who harbored misconceptions about breastfeeding had twice the odds of feeding any prelacteals (OR: 2.09, 95% CI: 1.74-2.50). Health care factors increasing the odds of prelacteal feeding included delivery by caesarean section (OR: 2.94, 95% CI: 2.39-3.61) or episiotomy (OR: 1.36, 95% CI: 1.17-1.58) and experiencing breastfeeding problems (OR: 1.31, 95% CI: 1.04-1.66). Health staff support during pregnancy and after birth reduced the odds of feeding formula. However, family support after delivery increased the odds of feeding water to newborns.

CONCLUSIONS

The multiple factors contributing to the high prevalence of prelacteal feeding behaviors stress the need for early and appropriate breastfeeding interventions in Vietnam, particularly during routine healthcare contacts. Improving breastfeeding practices during the first days of an infant's life could be achieved by improving knowledge and confidence of mothers through appropriate perinatal counseling and support. Ensuring that health facilities integrate these practices into routine ante-natal care and post-delivery management is critical.

Effect of sponge volume fraction on the performance of a novel fluidized bed bioreactor

A novel fluidized bed bioreactor (FBBR) was designed by integration of anaerobic granular activated carbon and aerobic sponge reactors. This FBBR was evaluated at different sponge volume fractions for treating a synthetic wastewater. Polyester urethane sponge with cube size of 1 × 1 × 1 cm and density of 28-30 kg/m(3) with 90 cells per 25 mm was used as biomass carrier. The results indicate that the FBBR could remove more than 93% of dissolved organic carbon (DOC). The highest nutrient removal efficiencies (58.2% PO4-P and 75.4% NH4-N) were achieved at 40% sponge volume fraction. The system could provide a good condition for biomass growth (e.g. 186.2 mg biomass/g sponge). No significant different performance in specific oxygen uptake rate was observed between 30, 40, and 50% sponge volume fractions.

Use of a United States-based laboratory as a hematopathology reference center for a developing country: logistics and results

INTRODUCTION

With proper logistical support and sponsorship, a laboratory in an industrialized nation might be able to act as a reference laboratory for clinicians based in a developing country.

METHODS

We built on previous experience in the clinical laboratory to see whether a specialized histopathology service (hematopathology) could be provided to a developing country without the expertise or experience to do it in country.

RESULTS

Over an 13-year period, 582 cases from 579 individuals were analyzed. Principal pathologic findings included acute leukemia in 84 cases (14%), dyspoiesis in one or more of the hematopoietic lineages in 65 cases (11%, including three cases with high-grade myelodysplasia), 23 cases (4%) with findings suspicious for a chronic myeloproliferative disorder, 35 cases (6%) with findings suspicious for a lymphoproliferative disorder, and infectious organisms (presumably Leishmania in most instances) in 9 (1%) of cases. Specimens from 45 cases (8%) were unsatisfactory owing to extreme hemodilution and/or specimen degeneration.

CONCLUSION

With proper support, a medical laboratory in an industrialized nation may serve as a reference facility for a developing nation. The use of existing infrastructure may be remarkably effective to achieve optimal turnaround time. Although the lack of ancillary studies and follow-up biopsies limit the ability to achieve a definitive diagnosis in many cases, this must be viewed in the context of the limited ability to diagnose or manage hematopoietic neoplasia in developing nations.

Novel versus traditional risk markers for diabetic retinopathy

AIMS/HYPOTHESIS

To explore the relative contribution of novel and traditional risk markers for diabetic retinopathy (DR).

METHODS

A clinic-based study of 224 diabetic patients (85 type 1, 139 type 2) from a diabetes clinic was performed. DR was graded from fundus photographs according to the Airlie House Classification system and classified as absent or present (at least ETDRS level 14). Novel risk markers assessed included serum apolipoprotein (Apo) AI and B, skin microvascular responses to acetylcholine (endothelium-dependent) and sodium nitroprusside (endothelium-independent) iontophoresis, flicker-light-induced retinal vasodilation and retinal vascular tortuosity. Relative contribution was determined by semi-partial correlation coefficient generated from a logistic regression model containing all traditional and novel risk markers simultaneously.

RESULTS

There were 144 (64.3%) participants with DR. Of the novel markers, ApoAI, flicker-light-induced vasodilation and retinal arteriolar tortuosity were significantly associated with DR, independently of traditional measures (all p < 0.03). Diabetes duration contributed most (51%) to the risk of DR, followed by ApoAI (16%), systolic blood pressure (13%), retinal arteriolar tortuosity (8%) and flicker-light-induced venular and arteriolar dilation (3% and 0.5%, respectively).

CONCLUSIONS/INTERPRETATION

ApoAI and retinal arteriolar tortuosity made considerable contributions to DR risk, independently of traditional risk markers. Findings from this study suggest that serum ApoAI and retinal arteriolar tortuosity may be novel and independent risk markers of DR.

The efficacy of entecavir therapy in chronic hepatitis B patients with suboptimal response to adevofir

BACKGROUND

An increasing number of patients with chronic hepatitis B (CHB) have experienced treatment failure to adefovir (ADV) and their management poses a growing challenge. Very limited data are available on the efficacy of entecavir (ETV) in patients previously treated with ADV.

AIM

To examine the effect of ETV monotherapy on HBV DNA and ALT levels in CHB patients previously treated with ADV, but switched to ETV due to suboptimal response.

METHODS

Study candidates were enrolled from five community gastroenterology clinics in the U.S. Each completed at least 12 months of ETV treatment after being previously treated with ADV and experiencing suboptimal response. Primary and secondary outcome measurements were complete viral suppression (CVS, HBV DNA <100 IU/mL) and biochemical response (BR, ALT < 40 U/L), respectively.

RESULTS

A total of 60 patients were included in this analysis. Twelve were lamivudine (LAM)-experienced and none were LAM-resistant. At time of switch to ETV, no patients had experienced CVS. The CVS rate was 68% after 12 months of ETV therapy. The BR rate was 67% at switch to ETV and 80% after 12 months. There was no significant difference in response rates between LAM-experienced and naïve patients. Among the eight patients with ADV resistance, each achieved CVS after 12 months of ETV therapy and seven achieved BR.

CONCLUSIONS

In patients with suboptimal response to adefovir, complete viral suppression and biochemical response can be achieved in the majority by 12 months after switching to entecavir, including patients with prior exposure to lamivudine and those with adefovir resistance.

Retinal vascular tortuosity in persons with diabetes and diabetic retinopathy

AIM/HYPOTHESIS

The aim of this hypothesis was to examine the association of retinal vessel tortuosity with diabetes and diabetic retinopathy (DR).

METHODS

A clinic-based study of 327 participants (224 with diabetes and 103 non-diabetic controls) aged ≥ 18 years. DR was graded from fundus photographs according to the modified Airlie House Classification system and categorised into mild non-proliferative DR (NPDR), moderate NPDR and vision-threatening DR (VTDR). Retinal vessel tortuosity was measured from disc-centred retinal photographs. Measurements were taken, using a semi-automated computer program by a single grader, of arterioles and venules within 0.5 to 2 disc diameters away from the optic disc.

RESULTS

There were 114 (44%) participants with DR. In the multivariate analysis, retinal arteriolar and venular tortuosity were increased in participants with diabetes without DR (mean difference 12.4 × 10(-5) and 13.3 × 10(-5), respectively; both p < 0.05) and in those with DR (mean difference 15.4 × 10(-5) and 15.0 × 10(-5), respectively; both p < 0.01) compared with non-diabetic participants. Among participants with diabetes, increased arteriolar tortuosity was significantly associated with mild NPDR (OR 1.53, 95% CI 1.03-2.05, per SD increase in arteriolar tortuosity) and moderate NPDR (OR 1.67, 95% CI 1.10-2.55) but not VTDR (OR 0.91, 95% CI 0.54-1.54). No association with DR was found for venular tortuosity.

CONCLUSIONS/INTERPRETATION

Persons with diabetes had more tortuous retinal vasculature than persons without diabetes. In persons with diabetes, increased arteriolar tortuosity was associated with mild and moderate stages of DR. This suggests that retinal vascular tortuosity might be an early indicator of microvascular damage in diabetes; thus, further investigation is indicated.

State of the art in myeloid sarcoma

INTRODUCTION

Myeloid sarcomas are extramedullary lesions composed of myeloid lineage blasts that typically form tumorous masses and may precede, follow, or occur in the absence of systemic acute myeloid leukemia. They most commonly involve the skin and soft tissues, lymph nodes, and gastrointestinal tract and are particularly challenging to diagnose in patients without an antecedent history of acute myeloid leukemia.

METHODS

We conducted a search of the English language medical literature for recent studies of interest to individuals involved in the diagnosis of myeloid sarcoma.

RESULTS

The differential diagnosis includes non-Hodgkin lymphoma, blastic plasmacytoid dendritic cell neoplasm, histiocytic sarcoma, melanoma, carcinoma, and (in children) small round blue cell tumors. The sensitivity and specificity of immunohistochemical markers must be considered when evaluating a suspected case of myeloid sarcoma. A high percentage of tested cases have cytogenetic abnormalities.

CONCLUSION

A minimal panel of immunohistochemical markers should include anti-CD43 or anti-lysozyme as a lack of immunoreactivity for either of these sensitive markers would be inconsistent with a diagnosis of myeloid sarcoma. Use of more specific markers of myeloid disease, such as CD33, myeloperoxidase, CD34 and CD117 is necessary to establish the diagnosis. Other antibodies may be added depending on the differential diagnosis. Identification of acute myeloid leukemia-associated genetic lesions may be helpful in arriving at the correct diagnosis.

Efficacy and safety of the dipeptidyl peptidase-4 inhibitor PF-734200 added to metformin in Type 2 diabetes

AIMS

  PF-734200 is a potent and selective oral dipeptidyl peptidase-4 (DPP-4) inhibitor. This study assessed the efficacy and safety of PF-734200 at dose rates of 20 and 30 mg/day in subjects with Type 2 diabetes mellitus inadequately controlled on metformin monotherapy.

METHODS

  This was a placebo-controlled, double-blind, randomized, multicentre, 12 week study. Subjects with Type 2 diabetes mellitus were eligible if screening glycosylated haemoglobin (HbA(1c) ) was 7-11% (53.0-96.7 mmol/mol) and they had been receiving metformin monotherapy for ≥2 months. Subjects receiving metformin and an insulin secretagogue or metformin and thiazolidinedione needed to have a screening HbA(1c) of 6.5-9.5% (47.5-80.3 mmol/mol), measured prior to discontinuing the insulin secretagogue or thiazolidinedione. The primary end-point of the study was a change from baseline to week 12 in HbA(1c) levels.

RESULTS

  Baseline characteristics for 289 subjects randomized to PF-734200 or placebo groups were similar (mean age 56.5 years, mean body mass index 32.2 kg/m(2) and mean HbA(1c) 8.2%, 66.1 mmol/mol). In the predefined per protocol data set, least-squares mean HbA(1c) at week 12 was reduced by 0.79 (8.6 mmol/mol 95% confidence interval -1.10 to -0.49, -12.0 to -5.4 mmol/mol) and 0.92% (10.1 mmol/mol; -1.23 to -0.61, -13.4 to -6.7 mmol/mol) in the 20 and 30 mg groups, respectively, compared with placebo. Differences from placebo were statistically significant (P<0.0001), but the differences between the 20 and 30 mg groups were not. The intent-to-treat analysis yielded similar findings.

CONCLUSIONS

  The HbA(1c) was significantly and meaningfully reduced by both doses of PF-734200, but 20 mg appears to be the more appropriate therapeutic dose for Type 2 diabetes mellitus, contingent upon confirmation by long-term controlled studies.

The Second National Oral Health Survey of Vietnam, 1999: background and methodology

Few high-quality epidemiological surveys of oral health have been conducted in developing countries. A National Oral Health Survey of Vietnam was previously conducted in 1989.

OBJECTIVE

To conduct a Second National Oral Health Survey to facilitate planning of preventive and treatment programmes and the dental workforce in Vietnam.

DESIGN

The 1999 survey utilised a multistage stratified random sampling strategy to obtain a random sample of the Vietnamese population. The population was stratified by province, urban/rural location and age in order to ensure adequate representation. Participants were clustered into schools (children) or communes (adults). Data were collected through a social survey, and dental examinations were conducted by calibrated examiners.

RESULTS

High percentages of the target samples in each stratum were obtained. Inter-examiner and intra-examiner reliability were good to high (kappa: 0.48-0.98). All data were weighted to adjust for the probabilities of selection and known biases to provide unbiased estimates at provincial and national level.

CONCLUSION

The National Oral Health Survey of Vietnam was a high-quality epidemiological survey with high participation rates. This was made possible through strong support from the Vietnamese Ministry of Health and regional and local officials.

Baseline characteristics and early on-treatment response predict the outcomes of 2 years of telbivudine treatment of chronic hepatitis B

BACKGROUND/AIMS

In the GLOBE trial, telbivudine treatment was identified as a significant, independent predictor of better outcomes at 2 years. We analyzed all telbivudine recipients in this trial to determine the predictors of optimal outcomes.

METHODS

The intent-to-treat population comprised 458 HBeAg-positive and 222 HBeAg-negative telbivudine-treated patients. Multivariate logistic regression analyses were employed to evaluate baseline and/or early on-treatment variables.

RESULTS

Baseline HBV DNA<9 log(10)copies/mL, or ALT levels > or = 2x above normal were strong pretreatment predictors for HBeAg-positive, but not for HBeAg-negative patients. However, non-detectable serum HBV DNA at treatment week 24 (TW24) was the strongest predictor for better outcomes for both groups. A combination of pretreatment characteristics plus TW24 response identified subgroups with the best outcomes: (1) HBeAg-positive patients with baseline HBV DNA<9 log(10)copies/mL, ALT > or = 2x above normal and non-detectable HBV DNA at TW24 achieved at 2 years: non-detectable HBV DNA in 89%, HBeAg seroconversion in 52%, telbivudine resistance in 1.8%; and (2) HBeAg-negative patients with baseline HBV DNA<7 log(10)copies/mL and non-detectable serum HBV DNA at TW24 achieved at 2 years: non-detectable HBV DNA in 91%, telbivudine resistance in 2.3%.

CONCLUSION

During telbivudine treatment, non-detectable serum HBV DNA at treatment week 24 is the strongest predictor for optimal outcomes at 2 years.

Exploring the genetic link between RLS and ADHD

Attention deficit/hyperactivity disorder (ADHD) is a highly heritable neurodevelopmental disorder of childhood onset. Clinical and biological evidence points to shared common central nervous system (CNS) pathology of ADHD and restless legs syndrome (RLS). It was hypothesized that variants previously found to be associated with RLS in two large genome-wide association studies (GWA), will also be associated with ADHD. SNPs located in MEIS1 (rs2300478), BTBD9 (rs9296249, rs3923809, rs6923737), and MAP2K5 (rs12593813, rs4489954) as well as three SNPs tagging the identified haplotype in MEIS1 (rs6710341, rs12469063, rs4544423) were genotyped in a well characterized German sample of 224 families comprising one or more affected sibs (386 children) and both parents. We found no evidence for preferential transmission of the hypothesized variants to ADHD. Subsequent analyses elicited nominal significant association with haplotypes consisting of the three SNPs in BTBD9 (chi2 = 14.8, df = 7, nominal p = 0.039). According to exploratory post hoc analyses, the major contribution to this finding came from the A-A-A-haplotype with a haplotype-wise nominal p-value of 0.009. However, this result did not withstand correction for multiple testing. In view of our results, RLS risk alleles may have a lower effect on ADHD than on RLS or may not be involved in ADHD. The negative findings may additionally result from genetic heterogeneity of ADHD, i.e. risk alleles for RLS may only be relevant for certain subtypes of ADHD. Genes relevant to RLS remain interesting candidates for ADHD; particularly BTBD9 needs further study, as it has been related to iron storage, a potential pathophysiological link between RLS and certain subtypes of ADHD.

The association between body mass index and hypertension is different between East and Southeast Asians

BACKGROUND

Few studies have allowed direct comparison of the association between body mass index (BMI; in kg/m2) and hypertension in different Asian ethnicities.

OBJECTIVE

We compared the association of BMI with hypertension in Chinese, Indonesian, and Vietnamese adults and determined BMI cutoffs that best predicted hypertension in these populations.

DESIGN

We included 7562 Chinese, 18,502 Indonesian, and 77,758 Vietnamese participants aged 18-65 y. Blood pressure, weight, and height were measured by trained health workers. To define an optimal BMI cutoff, we computed and searched for the shortest distance on receiver operating characteristic curves.

RESULTS

Despite a low mean BMI, the prevalences of hypertension in Chinese, Indonesian, and Vietnamese men were 22.9%, 24.8%, and 14.4%, respectively, and in women were 16.6%, 26.9%, and 11.7%, respectively. At all BMI levels, the sex-specific prevalence of hypertension was higher in Indonesian adults than in Chinese and Vietnamese adults (P < 0.05 at almost all BMI levels). The overall and stratified analyses suggested optimal BMI cutoffs of 23-24, 21-22.5, and 20.5-21 for Chinese, Indonesian, and Vietnamese adults, respectively. The cutoffs were approximately 0.5-1.0 units higher in women than in men and in the older (41-65 y) than in the younger (18-40 y) participants.

CONCLUSIONS

The study showed an ethnic difference in the BMI-hypertension association and in optimal BMI cutoffs between Chinese, Indonesian, and Vietnamese adults. Country-specific or even country-, sex-, and age-specific BMI cutoffs might be needed to identify persons at high risk of cardiovascular diseases.

Incidence and significance of profound hypotension during dobutamine stress echocardiography

BACKGROUND

Mild hypotension (drops of systolic blood pressure of > or = 20 mmHg) occurs in 14-38% of dobutamine stress echo (DSE) and carries a good prognosis for subsequent cardiac events. The incidence and significance of more profound hypotension (PH) (> or = 50 mmHg) is unknown.

HYPOTHESIS

The aim of the study was to determine the incidence of PH during DSE and its prognosis for subsequent cardiac events.

METHODS

We reviewed 617 DSE performed at our institution between 1992 and 1996 and identified two DSE subgroups. The first group (PH group) consisted of all patients with PH during DSE. A second group was selected with baseline characteristics similar to the PH group but without PH during DSE (non-PH group). Follow-up was by a physician chart review and direct telephone contact. Cardiac event rates were determined for hard [myocardial infarction (MI), or cardiac death] and soft (angina, congestive heart failure, coronary angioplasty, or coronary bypass surgery) events occurring after the DSE.

RESULTS

Of the 617 DSE performed, 16 (3%) patients developed PH (PH group) during DSE, with 13 showing no inducible ischemia. The hard and soft cardiac event rate in this 13 PH group was 46% (mean follow-up of 28.7 +/- 18 months). Of the non-PH group, 32 patients had a negative DSE with a coronary event rate of 12.5%. Profound hypotension correlated with a significantly higher cardiac event rate (p < 0.02).

CONCLUSIONS

The incidence of PH during DSE is low (3%) and appears to predict a worse prognosis for subsequent cardiac events.

TCF7L2 polymorphism rs7903146 and predisposition for type 2 diabetes mellitus in obese children

Polymorphism RS7903146 in transcription factor 7-like2 gene ( TCF7L2) is associated with type 2-diabetes mellitus (T2DM) in adults. Concerned with predisposition for diabetes mellitus in obese children, we tested if risk genotypes TC and TT of rs7903146 are more common in obese children with increased homeostasis model assessment insulin resistance index (HOMA-IR) compared to obese controls with normal HOMA-IR. As exploratory analysis, we also calculated beta-cell function for these risk genotypes and measured glucagon-like peptide 1 (GLP-1) in a subgroup. The cohort was 401 obese children (BMI > 2SDS; 211 female; 59% presenting increased HOMA-IR) from two German outpatient obesity referral centers. Genotype distributions in patients presenting increased HOMA-IR (TT: 10.18%, CT: 35.65%, CC: 54.17%) and in patients with normal HOMA-IR (TT: 8.66%, CT: 42.67%, CC: 48.67%) provided no significant effect of these two risk genotypes (p > 0.2). Correction for possible confounder's gender, age, pubertal stage, and BMI revealed no association with glucose metabolism parameters including GLP-1. However, exploratory HOMA-B% index was comparatively higher in TT-homozygotes (p=0.021) as compared to CC-homozygotes. We conclude that even though TT and CT genotypes were not higher in patients presenting elevated HOMA-IR, the higher HOMA-B% index in TT-homozygotes indicates TCF7L2 to be a susceptibility gene for the development of impaired glucose tolerance in obese children as demonstrated in several adult cohort studies.

Behavioral and pathological outcomes in MOG 35-55 experimental autoimmune encephalomyelitis

We measured inflammatory and neural markers of disease from 7 days to one year after induction of experimental autoimmune encephalomyelitis (EAE) by immunization with myelin oligodendrocyte glycoprotein (MOG) peptide. Axon loss began before behavioral signs when T cell infiltration and microglial activation were very subtle. Remyelination was only detectable ultrastructurally. Axon numbers in the dorsal column plateau around day 30 p.i. while behavioral measures (EAE scores, rotarod, grip strength) partially recover. These results provide a starting point for testing potential neuroprotective treatments for multiple sclerosis (MS).

Genome-wide linkage analysis of ADHD using high-density SNP arrays: novel loci at 5q13.1 and 14q12

Previous genome-wide linkage studies applied the affected sib-pair design; one investigated extended pedigrees of a genetic isolate. Here, results of a genome-wide high-density linkage scan of attention-deficit/hyperactivity disorder (ADHD) using an array-based genotyping of approximately 50 K single nucleotide polymorphism (SNPs) markers are presented. We investigated eight extended pedigrees of German origin that were non-related, not part of a genetic isolate and ascertained on the basis of clinical referral. Two parametric analyses maximizing LOD scores (MOD) and a non-parametric analysis for both a broad and a narrow phenotype approach were conducted. Novel linkage loci across all families were detected at 2q35, 5q13.1, 6q22-23 and 14q12, within individual families at 18q11.2-12.3. Further linkage regions at 7q21.11, 9q22 and 16q24.1 in all families, and at 1q25.1, 1q25.3, 9q31.1-33.1, 9q33, 12p13.33, 15q11.2-13.3 and 16p12.3-12.2 in individual families replicate previous findings. High-resolution linkage mapping points to several novel candidate genes characterized by dense expression in the brain and potential impact on disorder-relevant synaptic transmission. Our study provides further evidence for common gene effects throughout different populations despite the complex multifactorial etiology of ADHD.

Structural transitions of encapsidated polyelectrolytes

Conformations and structural transitions of polyelectrolytes strictly confined onto a spherical 2D surface have been investigated by scaling descriptions based on physical arguments concerning polyelectrolyte adsorption onto planar surface and liquid crystals as well as by Monte Carlo simulations using a bead-spring model with short-range and electrostatic repulsions. In case of the electrostatic screened regime, a disordered-ordered (spiral) transition at increasing persistence length of the chain was found. It was predicted that the transition occurred when the persistence length is comparable with the mean spacing between adjacent strands of the ordered chain. The presence of a non-screened electrostatic repulsion led to a more complex behavior with i) a re-entrant order-disorder transition and ii) a tennis ball texture as an additional smectic/nematic structure. The various competing structures given by the theory were recovered by the Monte Carlo simulations, which also indicated that the tennis ball texture was favored over the spiral structure by the long-range interactions for semi-flexible chains.

Prognostic factors associated with response in platinum retreatment of platinum-resistant ovarian cancer

The goal of this study was to determine the factors associated with response to platinum retreatment in patients with platinum-resistant ovarian cancer. A review of patients with epithelial ovarian cancer retreated with cisplatin or carboplatin between 2002 and 2004 was performed. The platinum-free interval (PFI) and treatment-free interval (TFI) were determined for each patient. Response was based on serial CA125 levels using a modification of the Rustin criteria. Patients with clinical benefit ([CB] those who attained at least stable disease) were compared to patients with disease progression (PD). An analysis was performed to determine factors associated with CB in platinum-resistant patients retreated with platinum. Of 48 patients identified, 37 were evaluable included in this analysis. CB was observed in 27 (73%) while disease progression was noted in 10 (27%) women. The PFI was longer in those women who achieved CB (12.3 vs 6.9 months; P = 0.02). The TFI was 7.1 months for patients benefited from platinum retreatment vs 3.5 months for those with disease progression (P = 0.06). There was no statistically significant difference in the number of cytotoxic agents between the time of platinum retreatment and the prior platinum regimen (2 vs 1.5 months; P = 0.61). A prolonged PFI was associated with an improved chance of achieving CB with platinum retreatment. There was no association between the response to platinum retreatment and the number of intervening cytotoxic agents utilized. Further prospective study is warranted to define the optimal timing of platinum retreatment.

No association of sequence variants in the neuropeptide Y2 receptor (NPY2R) gene with early onset obesity in Germans

The neuropeptide Y2 receptor (NPY2R) has been implicated in body weight regulation both in humans and rodents. We investigated if genetic variation in the NPY2R gene is associated with obesity in German extremely obese children and adolescents. The coding sequence and predicted promoter of the NPY2R were screened for variations. Subsequently, case-control (184 extremely obese children and adolescents: mean body mass index [BMI] 35.7+/-6.1 kg/m(2), 277 lean students: mean BMI 18.2+/-1.1 kg/m(2)) and family-based (770 parental pairs with a total of 1081 obese off-spring) association analyses were conducted in independent samples. We identified 14 sequence variants (seven novel variants including two coding variants c.369C >T and c.834G >A), five of which were detected once, each in the heterozygous state. In case-control analyses we did not detect association with obesity for seven common (minor allele frequency >1%) variants (all p >0.16); additional gender-stratified analyses employing several genetic models and haplotype analyses were also nonsignificant. Furthermore, in a family-based association study for coding synonymous SNP rs1047214 (Ile195) we found no evidence for a transmission disequilibrium in the total or in the gender-stratified PDT analyses (all p >0.50). In conclusion, we did not find evidence for an involvement of genetic variation in the NPY2R in early onset obesity in German samples.

Radiation hybrid mapping of 18 positional and physiological candidate genes for arthrogryposis multiplex congenita on porcine chromosome 5

We report the chromosomal assignment of 18 porcine genes to human homologues using the INRA-Minnesota swine radiation hybrid panel (IMpRH). These genes (CACNA1C, COL2A1, CPNE8, C3F, C12ORF4, DDX11, GDF11, HOXC8, KCNA1, MDS028, TMEM106C, NR4A1, PHB2, PRICKLE1, Q6ZUQ4, SCN8A, TUBA8 and USP18) are located on porcine chromosome 5 (SSC5) and represent positional and functional candidates for arthrogryposis multiplex congenita (AMC), which maps to SSC5. CPNE8, PRICKLE1, Q6ZUQ4 and TUBA8 were mapped to the interval for pig AMC between microsatellites SW152 and SW904. Three SNPs in TUBA8 co-segregated with the AMC phenotype in 230 pigs of our research population without recombination and could be used as a genetic marker test for AMC. In addition, we provide evidence that a small chromosomal region of HSA22q11.2 evolutionarily corresponds to SSC5q12-q22 (and contains the human homologues of porcine SW152, Q6ZUQ4, TUBA8 and USP18), while the regions flanking HSA22q11.2 on SSC5 correspond to HSA12p13 and HSA12q12. We identified seven distinct chromosomal blocks, further supporting extensive rearrangements between genes on HSA12 and HSA22 in the AMC region on SSC5.

Continuum theory of retroviral capsids

We present a self-assembly phase diagram for the shape of retroviral capsids, based on continuum elasticity theory. The spontaneous curvature of the capsid proteins drives a weakly first-order transition from spherical to spherocylindrical shapes. The conical capsid shape which characterizes the HIV-1 retrovirus is never stable under unconstrained energy minimization. Only under conditions of fixed volume and/or fixed spanning length can the conical shape be a minimum energy structure. Our results indicate that, unlike the capsids of small viruses, retrovirus capsids are not uniquely determined by the molecular structure of the constituent proteins but depend in an essential way on physical constraints present during assembly.

Direct gene transfer in potato: a comparison of particle bombardment of leaf explants and PEG-mediated transformation of protoplasts

Direct gene transfer methods in potato would facilitate the transfer of multiple genes and the manipulation of metabolic pathways in this species. In this study, up to 1.8 transformation events per shot (=0.5 per bombarded leaf) and 67.2 events per million protoplasts treated were obtained with particle bombardment and PEG-mediated direct DNA uptake, respectively. Limited disassociation of both HPT and GUS genes appeared to occur during the process of integration in only 19% of transformants. A large number of transformed potato plants with transgene expression at levels comparable to Agrobacterium-mediated transformation was obtained. High levels of GUS expression were only obtained in lines derived from PEG treatment. No correlation between the number of gene insertions and gene expression levels was found, suggesting that multiple insertions may have little or no effect on transgene expression.

Surface charge relaxation and the pearling instability of charged surfactant tubes

The pearling instability of bilayer surfactant tubes was recently observed during the collapse of fluid monolayers of binary mixtures of Dimyristoylphosphocholine (DMPC): Palmitoyloleoylphosphoglycerol (POPG) and Dipalmitoylphosphocholine (DPPC):POPG surfactants. It can be explained by a Rayleigh-like instability under the action of the bilayer surface tension. The magnitude of surface tension is dictated by the electrostatic interaction between charged surfactants. Relaxation of charged molecules is proposed here as an additional mechanism driving the instability. We find the functional dependence of the electrostatic surface tension and relaxation energies on the screening length kappa(-1) explicitly. Relaxation lowers the cost of bending a tube into pearls making the cylindrical tube even more unstable. It is known that for the weak screening case in which the tube radius is smaller than the screening length of the solution, this effect is important. However, for the case of strong screening it is negligible. For the experiments mentioned, the situation is marginal. In this case, we show that the effect of relaxation remains small. It contributes about 20% to the total electrostatic energy.

Elasticity theory and shape transitions of viral shells

Recently, continuum elasticity theory has been applied to explain the shape transition of icosahedral viral capsids--single-protein-thick crystalline shells--from spherical to "buckled" or faceted as their radius increases through a critical value determined by the competition between stretching and bending energies of a closed two-dimensional (2D) elastic network. In the present work we generalize this approach to capsids with nonicosahedral symmetries, e.g., spherocylindrical and conical shells. One key additional physical ingredient is the role played by nonzero spontaneous curvature. Another is associated with the special way in which the energy of the 12 topologically required fivefold sites depends on the "background" local curvature of the shell in which they are embedded. Systematic evaluation of these contributions leads to a shape "phase" diagram in which transitions are observed from icosahedral to spherocylindrical capsids as a function of the ratio of stretching to bending energies and of the spontaneous curvature of the 2D protein network. We find that the transition from icosahedral to spherocylindrical symmetry is continuous or weakly first order near the onset of buckling, leading to extensive shape degeneracy. These results are discussed in the context of experimentally observed variations in the shapes of a variety of viral capsids.

Laparoscopic esophagectomy

Minimally invasive esophagectomy is emerging as an alternative option to open esophagectomy for benign and malignant esophageal diseases. This article provides a detailed review of the history of minimally invasive esophagectomy and an update on the currently accepted techniques for minimally invasive esophagectomy and its outcomes.

Application of bovine microsatellite markers for genetic diversity analysis of Swiss yak (Poephagus grunniens)

In order to assess the applicability of bovine microsatellite markers for population genetic studies in Swiss yak, 131 bovine microsatellite markers were tested on a panel of 10 animals. Efficient amplification was observed for 124 markers (94.6%) with a total of 476 alleles, of which 117 markers (94.3%) were polymorphic. The number of alleles per locus among the polymorphic markers ranged from two to nine. Seven loci (ILSTS005, BMS424B, BMS1825, BMS672, BM1314, ETH123 and BM6017) failed to amplify yak genomic DNA. Two cattle Y-chromosome specific microsatellite markers (INRA126 and BM861) amplified genomic DNA from both male and female yaks. However, two additional markers on cattle Y-chromosome (INRA124 and INRA189) amplified DNA from only males. Of the polymorphic markers, 24 microsatellites proposed by CaDBase for within- and cross-species comparisons and two additional highly polymorphic markers (MHCII and TGLA73) were used to investigate the genetic variability and the population structure of a Swiss yak herd that included 51 additional animals. The polymorphic information content ranged from 0.355 to 0.752, while observed heterozygosity (HO) ranged from 0.348 to 0.823. Furthermore, a set of 13 markers, organized into three multiplex polymerase chain reactions, was evaluated for routine parentage testing. This set provided an exclusion probability in a family of four yaks (both parents and two offspring) of 0.995. These microsatellites serve as useful tools for genetic characterization of the yak, which continues to be an important domestic livestock species.

Characterization of G-banded chromosomes of a female saola (Pseudoryx nghetinhensis,2n = 50) and X chromosome i dentification by means of fluorescent in situ hybridization

The saola (Pseudoryx nghetinhensis) is a newly discovered large mammal species, belongs to the subfamily Bovinae and is listed as being endangered. Due to the limitation of the material available, no cytogenetic studies have been carried out on this species. In the present study, preliminary cytogenetic analysis was undertaken on cultured female fibroblast cells to characterize the karyotype organization of saola. An examination of 120 Giemsa stained metaphases showed the diploid chromosome number of 2n = 50, including five bi-armed chromosome pairs. The distribution of constitutive heterochromatin in saola was studied. However, the variability in the size of C-bands was not significant on all the homologous chromosomes. The X chromosome pair, corresponding to the largest telocentric chromosomes, was identified by fluorescent in situ hybridization (FISH) using a bacterial artificial chromosome clone (BAC 0577G05, which maps to BTAXq25-->q33). In comparison to the standard karyotype of cattle (ISCNDB 2000), a G-banded ideogram of saola (about 390 band level) was presented. This work, therefore, provided a basic insight into the karyotype organization of this endangered species and will be particularly useful to improve the understanding of differences of genomes between related species.

Application of bovine microsatellite markers on Saola (Pseudoryx nghetinhensis)

The aim of the present study was to assess the applicability of bovine microsatellite markers on Saola (Pseudoryx nghetinhensis). A total of 127 microsatellite markers were tested on a male and a young female Saola. An efficient amplification was observed for 123 markers (96.8%), 73 markers (59.3%) were polymorphic. Four loci (BM2304, BMS1928, BMS779 and ILSTS006) on cattle chromosomes 1, 4, 7 and 8, respectively, failed to amplify in Saola. Two cattle Y-chromosome-specific microsatellite markers (INRA126 and BM861) were successfully amplified from both sexes in Saola. However, two additional markers (INRA124 and INRA189) on Y-chromosome failed to amplify in the female animal. These results show that most of the bovine microsatellite markers are applicable in Saola and therefore they can be used to study the phylogenetic relationships and the genetic diversity of the Saola population.

A novel lipase/chaperone pair from Ralstonia sp. M1: analysis of the folding interaction and evidence for gene loss in R. solanacearum

A microbial strain (referred to as M1) that produces an extracellular lipase was isolated from a soil sample in Vietnam, and identified as a Ralstonia species by partial sequencing of its 16S rDNA. A genomic library was constructed from Pst I fragments, and a colony showing lipase activity was selected for further analysis. Sequencing of the 4.7-kb insert in this clone (named M1-72) revealed one incomplete and three complete ORFs, predicted to encode a partial hypothetical glutaminyl tRNA synthetase (304 aa), a hypothetical transmembrane protein (500 aa), a lipase (328 aa) and a lipase chaperone (352 aa), respectively. Alignment of the insert sequence with the corresponding region of the genome of R. solanacearum GMI1000 (GenBank Accession No. AL646081) confirmed the presence in the latter of the genes for the hypothetical transmembrane protein and glutaminyl tRNA synthetase, which exhibited 89-91% identity to their counterparts in M1. However, R. solanacearum GMI1000 lacks the complete lipase-encoding gene and the major part of the chaperone-encoding gene, creating a so-called "black hole". The deduced amino acid sequences of the products of the lipase gene lipA and chaperone gene lipB from strain M1 shared 49.3-60.3% and 23.9-32.7% identity, respectively, with those of the Burkholderia lipase/chaperone subfamily I.2. lipB is located downstream of lipA, and separated from it by only 9 bp, and each gene has a putative ribosome binding site. The mature lipase LipA, a His-tagged derivative (LipAhis), the tagged full-length chaperone LipBhis and a truncated form (DeltaLipBhis) lacking the 56 N-terminal residues were expressed in Escherichia coli BL21. LipA, LipAhis and DeltaLipBhis could be expressed at high levels (70, 15 and 12 mg/g wet cells, respectively) and were easily purified. However, LipBhis was expressed at a much lower level which precluded purification. The specific activity of purified LipAhis, expressed on its own, was very low (<52 U/mg). However, after co-incubation with the purified DeltaLipBhis in vitro, the specific activity of the enzyme was markedly enhanced, indicating that the chaperone facilitated correct folding of the enzyme. A lipase:chaperone ratio of 1:10 was found to be optimal, yielding an enzyme preparation with a specific activity of 650 U/mg.

A Method for Matching the Refractive Index and Kinematic Viscosity of a Blood Analog for Flow Visualization in Hydraulic Cardiovascular Models

In this work, we propose a simple method to simultaneously match the refractive index and kinematic viscosity of a circulating blood analog in hydraulic models for optical flow measurement techniques (PIV, PMFV, LDA, and LIF). The method is based on the determination of the volumetric proportions and temperature at which two transparent miscible liquids should be mixed to reproduce the targeted fluid characteristics. The temperature dependence models are a linear relation for the refractive index and an Arrhenius relation for the dynamic viscosity of each liquid. Then the dynamic viscosity of the mixture is represented with a Grunberg-Nissan model of type 1. Experimental tests for acrylic and blood viscosity were found to be in very good agreement with the targeted values (measured refractive index of 1.486 and kinematic viscosity of 3.454 milli-m2/s with targeted values of 1.47 and 3.300 milli-m2/s).

Isolated intracranial infection with Mycobacterium avium complex

Mycobacterium avium-M. complex (MAC) has been linked to devastating respiratory and systemic illnesses in patients, especially in those who are immunosuppressed. The purpose of this study is to describe a case of isolated central nervous system (CNS) infection with MAC. This is a single case report of a patient with isolated intracranial mycobacterial infection.

SETTING

the patient was treated and the immunohistochemical investigations were undertaken at the National Institutes of Health in Bethesda, Maryland, USA.

INTERVENTION

the patient initially was treated with a cocktail of antimycobacterial medications. However, because his disease was refractory, he underwent a suboccipital craniotomy and evacuation of his cerebellar mass. The patient was determined to have a low production of interferon-gamma (INF-gamma) and tumor necrosis factor-alpha (TNF-alpha) when compared to normal values. Despite extensive radiographic imaging studies and biopsies, there was no evidence of another focus of MAC infection in this patient. We conclude that intracranial infectious lesions in patients such as ours should be treated with conventional systemic antibiotic regimens as the first-line of therapy. We suggest neurosurgical intervention in medically refractory cases of intracranial infections.

Profiling penciclovir susceptibility and prevalence of resistance of herpes simplex virus isolates across eleven clinical trials

Asusceptibility testing program was established to determine the prevalence of resistance to penciclovir among herpes simplex virus isolates collected from patients participating in 11 world-wide clinical trials involving penciclovir (topical or intravenous formulations) or famciclovir, the oral prodrug of penciclovir. These trials represented nine randomised double blind, placebo or aciclovir-controlled studies and two open-label studies. Groups surveyed included immunocompetent or immunocompromised patients receiving 2 to 12 months chronic suppressive therapy for genital herpes, immunocompetent patients with recurrent herpes labialis treated for four days, and immunocompromised patients with mucocutaneous herpes simplex virus (HSV). Another subset of patients had been identified as non-responders to aciclovir or to valaciclovir. This program assessed the susceptibility profile for a total of 2145 herpes simplex virus isolates from 913 immunocompetent and 288 immunocompromised patients treated with penciclovir, famciclovir, aciclovir or placebo (depending on trial design). HSV isolates were tested for susceptibility to penciclovir using the plaque reduction assay (PRA) in MRC-5 cells. Resistance was defined as an IC(50)>or=2.0 microg/ml or an IC(50)> 10-fold above the wild type control virus IC(50) within that particular assay. Penciclovir-resistant HSV was isolated from 0.22% immunocompetent patients, and 2.1% of immunocompromised patients overall and therefore the frequency of penciclovir-resistant herpes simplex virus in the immunocompetent population approximates that of aciclovir-resistant herpesvirus reported previously. Penciclovir-resistant HSV isolates were more common in isolates from immunocompromised patients, consistent with aciclovir clinical experience. Treatment with penciclovir (intravenous formulation) was associated with the development of resistant HSV in only one severely immunocompromised patient (day 7 isolate IC(50) = 2.01 microg/ml), although treatment was effective and resulted in the complete clearance of the lesion by day 8. No patients receiving topical penciclovir developed treatment-associated penciclovir-resistant HSV, and a single immunocompromised patient developed resistant HSV upon treatment with oral famiciclovir.

Interleukin-10 expression: is there a neglected contribution of CD8+ T cells in rheumatoid arthritis joints?

OBJECTIVE

To search for RA specific processes among T cell accumulation, T cell activation, or cytokine expression in CD4+ and CD8+ synovial fluid (SF) T cells.

METHODS

Flow cytometry of CD4+, CD8+, CD45RA+, CD45RO+, CD69 double or triple stained peripheral blood (PB) and SF T cells. IL-2, IL-10, and IFN-gamma expression was determined in PMA + ionomycin stimulated T cells on the single cell level. Concentrations of secreted IL-2, IL-4, IL-10, and IFN-gamma were quantified in the sera and synovial fluids by enzyme linked immunosorbent assay (ELISA).

RESULTS

A preferential recruitment of CD45RO+ memory T cells was found for CD4+ helper T cells, and in similar also for CD8+ suppressor T cells. An elevated CD69 expression was detected in memory, but also in CD45RA+ naive CD4+ and CD8+ SF T cells, whilst IL-2 expression was only demonstrable in a minor proportion of T cells populations. Preferential recruitment of memory T cells, but incomplete activation of naive and memory, CD4+ and CD8+ T cells were in similar found in RA and control patients. In RA but not in the control patients, a relevant proportion of CD4+ and CD8+ PB and SF T cells expressed IL-10 and IFN-gamma. High concentrations of IL-10, that were correlated with the amounts of secreted TNF-alpha, were only detected in RA joints.

CONCLUSION

Memory and naive T cell state of CD4+ and CD8+ T cell accumulates in the joints, and early T cell activation occur in similar patterns in RA and control patients. High IL-10 SF concentrations in contrast, and elevated percentages of IFN-gamma and IL-10 expressing CD4+ and CD8+ T cells in the PB and SF were characteristic for RA. Here, CD8+ T cells may contribute to high IL-10 concentrations in RA joints.

Central venous catheter-related bacteremia due to Tsukamurella species in the immunocompromised host: a case series and review of the literature

We report 6 cases of bacteremia due to Tsukamurella species, all of which were in immunosuppressed patients with indwelling central venous catheters (CVCs). Fewer than 20 cases of serious illness due to these gram-positive bacilli have been reported in the medical literature; these cases have mostly been ascribed to the species Tsukamurella paurometabola. Tsukamurella species are frequently misidentified as Rhodococcus or Corynebacterium species. We used high-performance liquid chromatography to identify these organisms to the genus level and 16S ribosomal RNA gene sequencing and DNA-DNA dot blots for species identification. Three of our isolates were identified as Tsukamurella pulmonis, 1 was identified as Tsukamurella tyrosinosolvans, and 1 was identified as a unique species. One isolate was not maintained long enough for species identification. All patients were successfully treated with antimicrobial therapy and CVC removal. Infection with this organism should be considered in the immunosuppressed patient with an indwelling CVC and gram-positive bacilli in the blood.

Persistence length of a polyelectrolyte in salty water: Monte Carlo study

We address the long standing problem of the dependence of the electrostatic persistence length l(e) of a flexible polyelectrolyte (PE) on the screening length r(s) of the solution within the linear Debye-Hückel theory. The standard Odijk, Skolnick, and Fixman (OSF) theory suggests l(e) proportional, variant r(2)s, while some variational theories and some computer simulations suggest l(e) proportional, variant r(s). In this paper, we use Monte Carlo simulations to study the conformation of a simple polyelectrolyte. Using four times longer PEs than in previous simulations and refined methods for the treatment of the simulation data, we show that the results are consistent with the OSF dependence l(e) proportional, variant r(2)s. The linear charge density of the PE, which enters in the coefficient of this dependence is properly renormalized to take into account local fluctuations.

Chronic caffeine treatment causes changes in cardiac adenosine receptor function in rats

Caffeine exerts a number of cardiovascular effects via antagonism of adenosine A1 and A2a receptors, and chronic caffeine intake has been suggested to be a preventable risk factor for cardiovascular disease. We attempted, therefore, to determine the effects of chronic caffeine treatment on adenosine receptor function and the heart rate and blood pressure of anaesthetized rats. Rats were given two weeks of drinking water containing either caffeine (0.2%) or tap water alone. Rats were then anaesthetized and blood pressure and heart rate was assessed, as well as cardiovascular responses to adenosine receptor agonists and antagonists. Following 2 weeks caffeine treatment, both the resting blood pressure and heart rate of the treated rats were significantly increased compared to the non-caffeine treated (147 +/- 5 compared to 161 +/- 3 mm Hg). Negative chronotropic responses to A1 receptor agonist N6 cyclopentyladenosine occurred at lower concentrations in caffeine-treated rats than control (2.5-fold decrease in the ED50 of bradycardic responses to N6 cyclopentyladenosine), whilst vasodilator and reflex tachycardic responses to A2a receptor agonist CGS 21680 were unchanged. A shorter duration of caffeine- treatment resulted in moderate increases in heart rate and bradycardic responses to N6 cyclopentyladenosine. In summary, we found changes in resting heart rate and blood pressure in caffeine-treated rats which were concurrent with changes in adenosine receptor function.

Model of inversion of DNA charge by a positive polymer: fractionalization of the polymer charge

We model one strand of DNA by a one-dimensional lattice (ODL) of negative charges and consider the problem of inversion of its charge by a positive polyelectrolyte (PE). In the neutral state of the ODL-PE complex, each of the ODL charges is locally compensated by a PE charge. When an additional PE molecule is adsorbed by ODL, its charge gets fractionalized into monomer charges of defects (tails and arches) on the background of the perfectly neutralized ODL. Defects spread all over the ODL, eliminating the self-energy of PE. For DNA this fractionalization mechanism leads to a substantial inversion of charge, a phenomenon which is widely used for gene delivery.

Kinetics of macroion coagulation induced by multivalent counterions

Due to the strong correlations between multivalent counterions condensed on a macroion, the net macroion charge changes sign at some critical counterion concentration. This effect is known as the charge inversion. Near this critical concentration the macroion net charge is small. Therefore, short range attractive forces between macroions dominate Coulomb repulsion and lead to their coagulation. The kinetics of macroion coagulation in this range of counterion concentrations is studied. We calculate the Coulomb barrier between two approaching like charged macroions at a given counterion concentration. Two different macroion shapes (spherical and rodlike) are considered. A new "self-regulated" regime of coagulation is found. As the size of aggregates increases, their charge and Coulomb barrier also grow and diminish the sticking probability of aggregates. This leads to a slow, logarithmic increase of the aggregate size with time.

Biochemical characterization of a virus isolate, recovered from a patient with herpes keratitis, that was clinically resistant to acyclovir

In vitro susceptibility assays of herpes simplex virus (HSV) do not necessarily correlate with treatment outcome. An HSV type 1 (HSV-1) isolate, N4, recovered from a patient who presented with herpes keratitis with localized immunosuppression, was characterized for susceptibility. Although the 50% inhibitory concentration (IC(50)) for this isolate was less than the accepted breakpoint for defining resistance to acyclovir (>2.0 microg/mL), the following lines of evidence suggest that the isolate was acyclovir resistant: (1) the clinical history confirmed that the infection was nonresponsive to acyclovir; (2) the in vitro susceptibility was similar to that of a thymidine kinase (TK)-negative, acyclovir-resistant virus SLU360; (3) the IC(50) of acyclovir was more than 10 times the IC(50) for an acyclovir-susceptible control strain; (4) plaque-purified clonal isolates were resistant to acyclovir (IC(50)s, >2.0 microg/mL); and (5) biochemical studies indicated that the HSV-1 N4 TK was partially impaired for acyclovir phosphorylation. Although residue changes were found in both the viral tk and pol coding regions of HSV-1 N4, characterization of a recombinant virus expressing the HSV-1 N4 polymerase suggested that the TK and Pol together conferred the acyclovir-resistance phenotype.

Inhibition of placental 11beta-hydroxysteroid dehydrogenase type 2 by catecholamines via alpha-adrenergic signaling

The placenta expresses high levels of 11beta-hydroxysteroid dehydrogenase type 2 (11betaHSD2) that converts cortisol into inactive 11-keto metabolites and effectively protects the developing fetus from maternal cortisol during pregnancy. Impairment of this glucocorticoid barrier has adverse effects on fetal outcomes. A similar spectrum of adverse fetal effects is induced by antenatal stress during pregnancy. To examine the hypothesis that physiological stress may regulate placental 11betaHSD2 gene expression, we examined the effects of the catecholamines norepinephrine (NE) and epinephrine (E) on 11betaHSD2 expression in human trophoblastic cells. With the use of Northern blotting and semiquantitative RT-PCR, we determined that NE and E rapidly downregulate 11betaHSD2 steady-state mRNA levels in early- and late-gestation human trophoblasts and BeWo trophoblastic cells. Experiments using different adrenoceptor subtype-selective agonists and antagonists demonstrated that this catecholamine suppression of 11betaHSD2 mRNA expression is mediated via both alpha(1)- and alpha(2)-adrenoceptors and is independent of beta-adrenergic stimulation. To examine transcriptional regulation, BeWo cells were transiently transfected with a reporter construct in which an 11betaHSD2 human promoter sequence was inserted upstream of the luciferase gene. Treatment with 10(-7) M NE decreased luciferase activity by ~60% (n = 3, P < 0.01). These results suggest the NE/E-mediated decrease in placental 11betaHSD2 gene expression is an instance of alpha-adrenoceptor-specific rapid transcriptional inhibition of an adrenergic target gene. This molecular mechanism may be involved in the deleterious effects of antenatal physiological stress on fetoplacental growth and development.