S. Shahrukh Hashmi

Loss of Tsc2 in Purkinje cells is associated with autistic-like behavior in a mouse model of tuberous sclerosis complex.

Tuberous sclerosis complex (TSC) is a dominant tumor suppressor disorder caused by mutations in either TSC1 or TSC2. TSC causes substantial neuropathology, often leading to autism spectrum disorders (ASDs) in up to 60% of patients. The anatomic and neurophysiologic links between these two disorders are not well understood. We have generated and characterized a novel TSC mouse model with Purkinje cell specific Tsc2 loss. These Tsc2f/-;Cre mice exhibit progressive Purkinje cell degeneration. Since loss of Purkinje cells is a well reported postmortem finding in patients with ASD, we conducted a series of behavior tests to asses if Tsc2f/-;Cre mice displayed autistic-like deficits. Tsc2f/-;Cre mice demonstrated increased repetitive behavior as assessed with marble burying activity. Using the three chambered apparatus to asses social behavior, we found that Tsc2f/-;Cre mice showed behavioral deficits, exhibiting no preference between a stranger mouse and an inanimate object, or between a novel and a familiar mouse. We also detected social deficits in Tsc2f/f;Cre mice, suggesting that Purkinje cell pathology is sufficient to induce ASD-like behavior. Importantly, social behavior deficits were prevented with rapamycin treatment. Altogether, these results demonstrate that loss of Tsc2 in Purkinje cells in a Tsc2-haploinsufficient background leads to autistic-like behavioral deficits. These studies provide compelling evidence that Purkinje cell loss and/or dysfunction may be an important link between TSC and ASD as well as a general anatomic phenomenon that contributes to the ASD phenotype.

Prevalence of nonsyndromic oral clefts in Texas: 1995–1999

Nonsyndromic cleft lip with/without cleft palate (NSCLP) and nonsyndromic cleft palate only (NSCPO) are common complex birth defects affecting 4,000 newborns annually. We undertook a descriptive study of oral clefts in Texas, focusing on the effect of folic acid fortification and Hispanic ethnicity on the prevalence of oral clefts as these factors have not previously been described. Data on 896 infants with NSCLP and NSCPO born between 1995 and 1999 in Texas were compared to all births in Texas during the same period. Prevalence odds ratios (POR) were calculated for maternal ethnicity, race, age, parity, public health region of residence, highest level of education, and infant gender. The effect of folic acid fortification on oral clefts was also examined. Compared with whites, adjusted POR were 0.97 (95% CIu2009=u20090.77–1.23) and 0.90 (95% CI 0.72–1.14) for NSCLP and 0.46 (95% CIu2009=u20090.30–0.72) and 0.62 (95% CIu2009=u20090.42–0.90) for NSCPO in foreign‐born and US‐born Hispanics, respectively. After fortification was implemented, the rate of NSCLP did not decrease. However, there was a 13% decrease in the prevalence of NSCPO (adjusted PORu2009=u20090.87, 95% CIu2009=u20090.68–1.15). Compared to whites, the rates in US‐born and foreign‐born Hispanic women were similar for NSCLP and much lower for NSCPO. The small reduction of 13% in NSCPO after folic acid fortification is imprecise and should be interpreted cautiously. Overall, it appears that folic acid fortification has had very little or no effect on the prevalence of oral clefts in infants born in Texas.

Survival of Texas infants born with trisomies 21, 18, and 13†

Trisomies 21, 18, and 13 are the three most common trisomies among infants who survive to 20 weeks gestation or more. Overall information about birth prevalence, natural history, and mortality for all three trisomies is well defined, but information about ethnic‐specific rates is limited. Only a few studies have examined mortality rates of trisomies 18 and 13 because so few cases are liveborn and most have very short life spans. This study assessed ethnic‐specific population‐based survival probabilities among infants for each trisomy. All cases of trisomies 21, 18, and 13 born in Texas between 1999 and 2003 were obtained from the Texas Birth Defects Registry and included 2,260 cases of trisomy 21, 398 cases of trisomy 18, and 213 cases of trisomy 13. Date and cause of death were obtained from the Texas vital statistics records and the National Death Index. Overall, birth prevalence rates (per 10,000 adjusted live births) for the three trisomies were 11.74 (95% CI: 11.25–12.25), 1.34 (95% CI: 1.18–1.52), 0.92 (95% CI: 0.79–1.07), respectively, and are consistent with previously reported rates. There were no differences in survival rates by ethnicity and the median survival for each trisomy was consistent with previous reports. The results of this study provide comprehensive population‐based information for survival of infants with trisomies 21, 18, and 13.

Glucose regulation of load-induced mTOR signaling and ER stress in mammalian heart.

Background Changes in energy substrate metabolism are first responders to hemodynamic stress in the heart. We have previously shown that hexose‐6‐phosphate levels regulate mammalian target of rapamycin (mTOR) activation in response to insulin. We now tested the hypothesis that inotropic stimulation and increased afterload also regulate mTOR activation via glucose 6‐phosphate (G6P) accumulation. Methods and Results We subjected the working rat heart ex vivo to a high workload in the presence of different energy‐providing substrates including glucose, glucose analogues, and noncarbohydrate substrates. We observed an association between G6P accumulation, mTOR activation, endoplasmic reticulum (ER) stress, and impaired contractile function, all of which were prevented by pretreating animals with rapamycin (mTOR inhibition) or metformin (AMPK activation). The histone deacetylase inhibitor 4‐phenylbutyrate, which relieves ER stress, also improved contractile function. In contrast, adding the glucose analogue 2‐deoxy‐d‐glucose, which is phosphorylated but not further metabolized, to the perfusate resulted in mTOR activation and contractile dysfunction. Next we tested our hypothesis in vivo by transverse aortic constriction in mice. Using a micro‐PET system, we observed enhanced glucose tracer analog uptake and contractile dysfunction preceding dilatation of the left ventricle. In contrast, in hearts overexpressing SERCA2a, ER stress was reduced and contractile function was preserved with hypertrophy. Finally, we examined failing human hearts and found that mechanical unloading decreased G6P levels and ER stress markers. Conclusions We propose that glucose metabolic changes precede and regulate functional (and possibly also structural) remodeling of the heart. We implicate a critical role for G6P in load‐induced mTOR activation and ER stress.

The differential effects of prenatal and/or postnatal rapamycin on neurodevelopmental defects and cognition in a neuroglial mouse model of tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is caused by heterozygous mutations in either the TSC1 (hamartin) or the TSC2 (tuberin) gene. Among the multisystemic manifestations of TSC, the neurodevelopmental features cause the most morbidity and mortality, presenting a considerable clinical challenge. Hamartin and tuberin form a heterodimer that inhibits the mammalian target of rapamycin complex 1 (mTORC1) kinase, a major cellular regulator of protein translation, cell growth and proliferation. Hyperactivated mTORC1 signaling, an important feature of TSC, has prompted a number of preclinical and clinical studies with the mTORC1 inhibitor rapamycin. Equally exciting is the prospect of treating TSC in the perinatal period to block the progression of brain pathologies and allow normal brain development to proceed. We hypothesized that low-dose rapamycin given prenatally and/or postnatally in a well-established neuroglial (Tsc2-hGFAP) model of TSC would rescue brain developmental defects. We developed three treatment regimens with low-dose intraperitoneal rapamycin (0.1 mg/kg): prenatal, postnatal and pre/postnatal (combined). Combined rapamycin treatment resulted in almost complete histologic rescue, with a well-organized cortex and hippocampus almost identical to control animals. Other treatment regimens yielded less complete, but significant improvements in brain histology. To assess how treatment regimens affected cognitive function, we continued rapamycin treatment after weaning and performed behavioral testing. Surprisingly, the animals treated with the combined therapy did not perform as well as postnatally-treated animals in learning and memory tasks. These results have important translational implications in the optimization of the timing and dosage of rapamycin treatment in TSC affected children.

Idiopathic talipes equinovarus (ITEV) (clubfeet) in Texas

Idiopathic talipes equinovarus (ITEV) is the most common form of clubfoot with a birth prevalence of 1 per 1,000 births. Serial casting and surgical correction impose a substantial financial burden on families and the health care system. While the etiology of ITEV is considered to be complex, the causes remain elusive. Genetic, maternal, and environmental factors have been suggested to play an etiologic role. This study was undertaken to determine the prevalence of ITEV and define maternal and environmental factors associated with ITEV in Texas from 1996 to 1999. Data on 682 cases of nonsyndromic ITEV were compared with all births (nu2009=u2009923,543) in Texas during the same period. The overall prevalence and prevalence odds ratios (PORs) were calculated for gender, year of birth, public health region (PHR), race, maternal age, education, folic acid fortification, and parity. The overall prevalence of ITEV was 0.74/1,000 or 1/1,354 live births. Adjusted PORs were similar among blacks and US and foreign‐born Hispanics (PORu2009=u20090.92, 95% CIu2009=u20090.69–1.21; PORu2009=u20090.99, 95% CIu2009=u20090.79–1.25; and PORu2009=u20090.94, 95% CIu2009=u20090.74–1.19), respectively, compared to whites. College education and higher parity were significantly associated with a lower risk of giving birth to offspring with ITEV. Babies born after folic acid fortification of grains had a very small decrease in ITEV that may be due to chance.

Maternal fever during early pregnancy and the risk of oral clefts.

An increased risk of birth defects after hyperthermic exposures has been confirmed in animal studies, but population studies have yielded inconsistent results. Oral clefts are a common birth defect and have been associated with these exposures in some of these studies. In this study, data from the National Birth Defects Prevention Study was used to evaluate the association of maternal report of febrile illness in early pregnancy and the risk of oral clefts. All oral cleft cases born between 1997 and 2004 were compared with nonmalformed controls born in the same geographical region during the same time period. Mothers reporting febrile illness during pregnancy were stratified by fever grade and antipyretic use. Logistic regression models were used to generate crude and adjusted odds ratios for exposure to fever and association with each oral cleft phenotype. The dataset included 5821 controls, 1567 cases of cleft lip with or without cleft palate (CL+/-P) and 835 cases of cleft palate only. A modestly increased risk was observed for isolated CL+/-P (odds ratio, 1.28; 95% confidence interval, 1.01-1.63). Stratification by fever grade (body temperature <101.5 degrees or > or =101.5 degrees F) did not yield significant differences in risk. Risk estimates were higher among women who reported a fever, but did not take antipyretics to control their fever, particularly for nonisolated compared with isolated oral clefts. This finding suggests that adequate control of fever may diminish the deleterious effects of fever in cases of oral cleft.

Multicenter imaging outcomes study of The Cancer Genome Atlas glioblastoma patient cohort: imaging predictors of overall and progression-free survival

BACKGROUNDnDespite an aggressive therapeutic approach, the prognosis for most patients with glioblastoma (GBM) remains poor. The aim of this study was to determine the significance of preoperative MRI variables, both quantitative and qualitative, with regard to overall and progression-free survival in GBM.nnnMETHODSnWe retrospectively identified 94 untreated GBM patients from the Cancer Imaging Archive who had pretreatment MRI and corresponding patient outcomes and clinical information in The Cancer Genome Atlas. Qualitative imaging assessments were based on the Visually Accessible Rembrandt Images feature-set criteria. Volumetric parameters were obtained of the specific tumor components: contrast enhancement, necrosis, and edema/invasion. Cox regression was used to assess prognostic and survival significance of each image.nnnRESULTSnUnivariable Cox regression analysis demonstrated 10 imaging features and 2 clinical variables to be significantly associated with overall survival. Multivariable Cox regression analysis showed that tumor-enhancing volume (P = .03) and eloquent brain involvement (P < .001) were independent prognostic indicators of overall survival. In the multivariable Cox analysis of the volumetric features, the edema/invasion volume of more than 85 000 mm(3) and the proportion of enhancing tumor were significantly correlated with higher mortality (Ps = .004 and .003, respectively).nnnCONCLUSIONSnPreoperative MRI parameters have a significant prognostic role in predicting survival in patients with GBM, thus making them useful for patient stratification and endpoint biomarkers in clinical trials.

Birth defects data from population-based birth defects surveillance programs in the United States, 2007 to 2011: Highlighting orofacial clefts

© 2014 The Authors Birth Defects Research Part A: Clinical and Molecular Teratology Published by Wiley Periodicals, Inc.

Genomic screening identifies novel linkages and provides further evidence for a role of MYH9 in nonsyndromic cleft lip and palate

Nonsyndromic cleft lip with or without cleft palate (NSCLP) is a common birth anomaly that requires prolonged multidisciplinary rehabilitation. Although variation in several genes has been identified as contributing to NSCLP, most of the genetic susceptibility loci have yet to be defined. To identify additional contributory genes, a high-throughput genomic scan was performed using the Illumina Linkage IVb Panel platform. We genotyped 6008 SNPs in nine non-Hispanic white NSCLP multiplex families and a single large African-American NSCLP multiplex family. Fourteen chromosomal regions were identified with LOD>1.5, including six regions not previously reported. Analysis of the data from the African-American and non-Hispanic white families revealed two likely chromosomal regions: 8q21.3–24.12 and 22q12.2–12.3 with LOD scores of 2.98 and 2.66, respectively. On the basis of biological function, syndecan 2 (SDC2) and growth differentiation factor 6 (GDF6) in 8q21.3–24.12 and myosin heavy-chain 9, non-muscle (MYH9) in 22q12.2–12.3 were selected as candidate genes. Association analyses from these genes yielded marginally significant P-values for SNPs in SDC2 and GDF6 (0.01≤P<0.05). Evidence for an altered transmission was found for four MYH9 SNPs (P<0.01). SNP rs1002246 exhibited altered transmission by all analytic methods. However, analysis of two SNP MYH9 haplotypes did not identify a single high-risk haplotype. Our results confirm a previous report that 8q21.3–24.12 may harbor a clefting gene and identify 22q12.2–12.3 as a new candidate region that contains MYH9. Most importantly, we confirm the previous report of an association with MYH9.