Gradient ascent pulse engineering for rapid exchange saturation transfer

Efforts in the clinical translation of the paraCEST contrast agent Yb-HPDO3A have prompted an investigation into saturation pulse optimality under energy constraints. The GRAPE algorithm has been adapted and implemented for saturation pulse optimization with chemical exchange. The flexibility of the methodology, both in extracting the microscopical parameter ensemble for the algorithm as well as in determining the characteristics of this new class of rising amplitude waveforms allows rapid testing and implementation. Optimal pulses achieve higher saturation efficiencies than the continuous wave gold standard for rapid and especially for variable exchange rates, as brought about by pH-catalysis. Gains of at least 5-15% without any tradeoff have been confirmed both on a spectrometer and on a clinical imager. Pool specific solutions, with pulses optimized for a specific exchange rate value, additionally increase the flexibility of the CEST ratiometric analysis. A simple experimental approach to determine close to optimal triangular pulses is presented.

Comparison of experimental infection with northern and southern Vietnamese strains of highly pathogenic porcine reproductive and respiratory syndrome virus

The aim of this study was to compare the virulence of northern and southern Vietnamese strains of highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) as assessed by the level of viral replication, gross and microscopical lung lesions and virus distribution in experimentally infected pigs. The northern and southern Vietnamese HP-PRRSV strains share 96.7% (non-structural protein 2) and 99.3% (open reading frame 5) nucleotide identity. On experimental challenge, approximately 50% of pigs infected with northern Vietnamese HP-PRRSV died, while death was not observed in any pigs infected with southern Vietnamese HP-PRRSV. Mean viral titres (expressed as log(10)TCID(50)/ml) were significantly (P <0.05) higher in sera and lungs from pigs infected with the northern Vietnamese HP-PRRSV than from those infected with the southern Vietnamese strain at multiple time points. Lung lesion scores and PRRSV antigen within pulmonary and lymphoid lesions were significantly (P <0.05) higher in pigs infected with northern Vietnamese HP-PRRSV than in those receiving southern Vietnamese HP-PRRSV at multiple time points. PRRSV antigens were observed in cardiac myocytes, gastric and renal tubular epithelial cells and astrocytes and microglia of white matter in the brain from pigs infected with the northern Vietnamese HP-PRRSV strain only. Thus, genetic similarity did not predict the degree of virulence of these strains. Northern Vietnamese HP-PRRSV was more virulent and had extended tissue tropism when compared with southern Vietnamese HP-PRRSV.

Comparison of pathogenicity of highly pathogenic porcine reproductive and respiratory syndrome virus between wild and domestic pigs

The objective of this study was to compare the pathogenicity of highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) infection between wild and domestic pigs based on clinical, immunological, and pathological evaluation. Upon challenge with HP-PRRSV, five wild pigs died compared to none of the domestic. Anti-PRRSV antibody titers were significantly (P < 0.05) higher in wild HP-PRRSV-infected pigs versus the domestic HP-PRRSV-infected pigs at 21 days post inoculation (dpi). Lung lesion scores at 7 dpi were also significantly (P < 0.01) higher in domestic infected pigs than wild infected pigs. The most striking difference was the viral tissue distribution between the wild and domestic HP-PRRSV-infected pigs. HP-PRRSV-positive cells were observed in bronchiolar, gastric, and renal tubular epithelial cells from wild HP-PRRSV-infected pigs only. The results in this study demonstrated a genetic difference exists between wild and domestic pigs, which could results in different clinical signs, immunological responses, and pathological outcomes to HP-PRRSV infection.

Wildlife disease. Recent introduction of a chytrid fungus endangers Western Palearctic salamanders

Emerging infectious diseases are reducing biodiversity on a global scale. Recently, the emergence of the chytrid fungus Batrachochytrium salamandrivorans resulted in rapid declines in populations of European fire salamanders. Here, we screened more than 5000 amphibians from across four continents and combined experimental assessment of pathogenicity with phylogenetic methods to estimate the threat that this infection poses to amphibian diversity. Results show that B. salamandrivorans is restricted to, but highly pathogenic for, salamanders and newts (Urodela). The pathogen likely originated and remained in coexistence with a clade of salamander hosts for millions of years in Asia. As a result of globalization and lack of biosecurity, it has recently been introduced into naïve European amphibian populations, where it is currently causing biodiversity loss.

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.

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.

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.

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.