Genotype frequencies at codon 129 of the Prion Protein Gene in Brazil: implications in susceptibility to variant Creutzfeldt--Jakob disease compared to European and Asian populations

A polymorphism at codon 129 of the prion protein gene has been shown to confer genetic susceptibility to prion diseases, and to influence the epidemic course of variant Creutzfeldt--Jakob disease. We employed a PCR-endonuclease digestion-based assay to investigate this genetic trait in Brazil, and then compared our results to previously published data from several European and Asian countries.Financial Support: Fundacao de Amparo a Pesquisa do Estado de São Paulo -- FAPESP     

Isolated sulfite oxidase deficiency: review of two cases in one family.

OBJECTIVE: The authors describe two cases of isolated sulfite oxidase deficiency found in one family. This is a rare autosomal-recessive disorder presenting at birth with seizures, severe neurologic disease, and ectopia lentis. It can be easily missed with metabolic screening; however, the finding of lens subluxation stresses the importance of ophthalmic assessment in making the diagnosis. DESIGN: Two observational case reports. INTERVENTION/METHODS: Ophthalmic assessment, biochemical assay for specific urinary and plasma metabolites, magnetic resonance imaging, and gene sequencing were used to make the diagnosis of the disease in the proband. The diagnosis was subsequently recognized in a previously affected sibling after the postmortem neuropathology was reviewed. Mutation analysis was performed on cultured fibroblasts from the proband to identify and categorize the specific mutation responsible for the disease in the family. From this, future prenatal detection of sulfite oxidase deficiency is possible. MAIN OUTCOME MEASURES: The diagnosis of sulfite oxidase deficiency was established in this family, enabling appropriate genetic counseling and recurrence risk estimation. RESULTS: Point mutations were found in both alleles of the sulfite oxidase gene in the proband. The first is a 623C-->A mutation, which predicts an A208D substitution, and the second is a 1109C-->A, which predicts an S370Y substitution. Both residues A208D and S370Y are critical for sulfite oxidase activity. CONCLUSIONS: Isolated sulfite oxidase deficiency is a rare heritable disease for which mutation analysis can allow accurate prenatal screening. It often is difficult to diagnose by clinical presentation alone, but the critical finding of lens subluxation accompanying seizures and diffuse neurologic disease in an infant should alert the physician to the diagnosis.     

Measurement of both left ventricular function and regional myocardial perfusion with 133Xe in dogs

A technique to measure left ventricular (LV) function and myocardial perfusion was validated in 12 dogs. ¹³³Xe in saline was injected into the left atrium (LA) or LV and two data sets were obtained using gamma camera imaging: 1) A first pass gated scan for LV function; followed by 2) Sequential images for regional myocardial perfusion. LV ejection fraction and wall motion measurements from the ¹³³Xe blood pool images were compared to ejection fraction (r=0.88, P<0.01) and wall motion (r=0.83, P<0.01) data from ^99mTc labeled blood pool scans. The perfusion measurements obtained with the ¹³³Xe method were compared to microsphere data (r=0.79, P<0.01). Measurements after LV ¹³³Xe injection were similar to data following LA injection. Thus, quantitative assessment of global LV function, regional wall motion and myocardial perfusion is possible with LA or LV ¹³³Xe injection and gamma camera imaging.     

On the specificity of the acetylcholinesterase defect in dystrophic mice

The tetrameric form of acetylcholinesterase (AChE) in ReJ/129 dystrophic mice was demonstrated to be absent from endplate-poor regions of skeletal muscle but present in endplate-rich regions. Skeletal muscle secreted normal amounts of this form of AChE. Visceral organs had normal amounts and distribution of the AChE molecular forms. These results suggest that the AChE defect in dystrophic mice is limited to skeletal muscle, and the defect does not reflect an abnormality of AChE synthesis but probably reflects an inability to incorporate the enzyme into skeletal muscle membranes.     

Microdialysis assessment of adipose tissue metabolism in post-absorptive obese NIDDM subjects

Abstract. Lactate and glycerol turnover is enhanced in obesity and NIDDM. To evaluate the influence of NIDDM on subcutaneous adipose tissue metabolism microdialysis combined with ¹³³Xe clearance and measurements in arterialized plasma were carried out using samples of subcutaneous abdominal fat from nine obese NIDDM subjects (glucose, 7.9 ± 0.7 mmol L^-1) (mean±SEM) and nine obese non-diabetic subjects (glucose, 4.9 ±0.1) matched for age, BMI and body fat. After an overnight fast arterialized plasma levels were 1145 ±110 vs. 876 ±59 μmol L^-1 ( P <0.05) for lactate and 75±10 vs. 66 ±8 μmol L^-1 for glycerol in the diabetic and control group, respectively. The corresponding abdominal subcutaneous interstitial lactate and glycerol concentrations were 1278 ± 63 vs 1107 ±64 μmolL^-1 and 314 ±28 vs. 311 ± 17μmol L^-1, respectively. However, adipose tissue blood flow in the same region was lower in NIDDM subjects (1.5±0.2 vs 2.4±0.3 mL 100g^-1 min^-1) ( P <0.05). Consequently, apparent subcutaneous lactate and glycerol release, estimated according to Fick, were not statistically different in the two groups (1.8 ±0.4 vs 2.4 ±0.8 and 2.1 ±0.4 vs 3.1 ±0.5 μmol kg^-1 min^-1 in NIDDM and control subjects, respectively). Thus, in the post-absorptive state apparent lactate and glycerol release by the abdominal subcutaneous tissue in obese NIDDM subjects was similar to that in a matched group of obese non-diabetic controls. The data suggest that no primary defect is evident in adipose tissue metabolism in well controlled NIDDM subjects.     

Transcranial Doppler Blood Flow Velocity versus 133Xe Clearance Cerebral Blood Flow During Mild Hypothermic Cardiopulmonary Bypass

Objective. Transcranial doppler (TCD) is used during cardiopulmonary bypass (CPB) to assess cerebral emboli and to estimate cerebral perfusion. We sought to compare TCD middle cerebral artery blood flow velocity (V_mca) to ¹³³Xe clearance cerebral blood flow (CBF) measurements during mild hypothermic CPB thus determining its utility in cerebral perfusion assessment. Methods. Thirty-four patients undergoing mild hypothermic CPB (35 °C) were studied and had comparisons of V_mca and ¹³³Xe CBF at three time intervals, 10, 30 and 60 min after the institution of CPB. Linear regression analysis was performed on data from each of the 3 intervals as well as for pooled data from all 3 periods. Results. The correlation coefficients for the 3 time periods were, r = 0.32 (p = 0.12), r = 0.32 (p = 0.11), r = 0.48 (p = 0.02), respectively. The pooled data correlation had a coefficient of 0.34 (p = 0.003). Conclusion. These findings suggest that TCD V_mca is a relatively poor correlate of CBF during mild hypothermic CPB.     

Ethanol‐Induced Increase of Agouti‐Related Protein (AgRP) Immunoreactivity in the Arcuate Nucleus of the Hypothalamus of C57BL/6J,but not 129/SvJ,Inbred Mice

Background: The melanocortin (MC) system is composed of peptides that are cleaved from the polypeptide precursor, pro‐opiomelanocortin (POMC). Previous research has shown that MC receptor (MCR) agonists reduce, and MCR antagonists increase, ethanol consumption in rats and mice. Consistently, genetic deletion of the endogenous MCR antagonist, agouti‐related protein (AgRP), causes reductions of ethanol‐reinforced lever pressing and binge‐like ethanol drinking in C57BL/6J mice. Ethanol also has direct effects on the central MC system, as chronic exposure to an ethanol‐containing diet causes significant reductions of α‐melanocyte stimulating hormone (α‐MSH) immunoreactivity in specific brain regions of Sprague‐Dawley rats. Together, these observations suggest that the central MC system modulates neurobiological responses to ethanol. To further characterize the role of the MC system in responses to ethanol, here we compared AgRP and α‐MSH immunoreactivity in response to an acute injection of saline or ethanol between high ethanol drinking C57BL/6J mice and moderate ethanol drinking 129/SvJ mice. Methods: Mice received an intraperitoneal (i.p.) injection of ethanol (1.5 g/kg or 3.5 g/kg; mixed in 0.9% saline) or an equivolume of 0.9% saline. Two hours after injection, animals were sacrificed and their brains were processed for AgRP and α‐MSH immunoreactivity. Results: Results indicated that acute ethanol administration triggered a dose‐dependent increase in AgRP immunoreactivity in the arcuate (ARC) of C57BL/6J mice, an effect that was not evident in the 129/SvJ strain. Although acute administration of ethanol did not influence α‐MSH immunoreactivity, C57BL/6J mice had significantly greater overall α‐MSH immunoreactivity in the ARC, dorsomedial, and lateral regions of the hypothalamus relative to the 129/SvJ strain. In contrast, C57BL/6J mice displayed significantly lower α‐MSH immunoreactivity in the medial amygdala. Conclusions: The results show that acute ethanol exposure has direct effects on endogenous AgRP activity in ethanol preferring C57BL/6J mice. It is suggested that ethanol‐induced increases in AgRP may be part of a positive feedback system that stimulates excessive binge‐like ethanol drinking in C57BL/6J mice. Inherent differences in α‐MSH immunoreactivity may contribute to differences in neurobiological responses to ethanol that are characteristically observed between the C57BL/6J and 129/SvJ inbred strains of mice.     

Defining sporadic Creutzfeldt-Jakob disease strains and their transmission properties

The biological determinants of the phenotypic variation in sporadic Creutzfeldt-Jakob disease (sCJD) are unknown. To categorize sCJD cases, the prion protein (PrP) codon 129 genotype and the biochemical characteristics of the disease-associated form of PrP (PrP^Sc) can be combined to form six subgroups (MM1, MM2, MV1, MV2, VV1, and VV2). This classification largely correlates with the known variation in the clinical and pathological features of sCJD, with the MM1 and MV1 cases representing the “classic” phenotype of sCJD. To address how this classification relates to different strains of sCJD we have inoculated each subgroup of sCJD to a panel of mice expressing different forms of the human PRNP gene (129MM, 129VV, and 129MV). We have established that all subtypes are transmissible to at least one genotype of mouse, and both agent and host factors determine transmission efficiency and the form of PrP^Sc deposited in the brain. Moreover, we have identified four distinct strains of sCJD using our in vivo strain typing panel.     

Local prolactin is a target to prevent expansion of basal/stem cells in prostate tumors

Androgen-independent recurrence is the major limit of androgen ablation therapy for prostate cancer. Identification of alternative pathways promoting prostate tumor growth is thus needed. Stat5 has been recently shown to promote human prostate cancer cell survival/proliferation and to be associated with early prostate cancer recurrence. Stat5 is the main signaling pathway triggered by prolactin (PRL), a growth factor whose local production is also increased in high-grade prostate cancers. The first aim of this study was to use prostate-specific PRL transgenic mice to address the mechanisms by which local PRL induces prostate tumorogenesis. We report that (i) Stat5 is the major signaling cascade triggered by local PRL in the mouse dorsal prostate, (ii) this model recapitulates prostate tumorogenesis from precancer lesions to invasive carcinoma, and (iii) tumorogenesis involves dramatic accumulation and abnormal spreading of p63-positive basal cells, and of stem cell antigen-1–positive cells identified as a stem/progenitor-like subpopulation. Because basal epithelial stem cells are proposed to serve as tumor-initiating cells, we challenged the relevance of local PRL as a previously unexplored therapeutic target. Using a double-transgenic approach, we show that Δ1–9-G129R-hPRL, a competitive PRL-receptor antagonist, prevented early stages of prostate tumorogenesis by reducing or inhibiting Stat5 activation, cell proliferation, abnormal basal-cell pattern, and frequency or grade of intraepithelial neoplasia. This study identifies PRL receptor/Stat5 as a unique pathway, initiating prostate tumorogenesis by altering basal-/stem-like cell subpopulations, and strongly supports the importance of further developing strategies to target locally overexpressed PRL in human prostate cancer.     

Measurement of 129Xe gas apparent diffusion coefficient anisotropy in an elastase‐instilled rat model of emphysema

Hyperpolarized noble gas (³He and ¹²⁹Xe) apparent diffusion coefficient (ADC) measurements have shown remarkable sensitivity to microstructural (i.e., alveolar) changes in the lung, particularly emphysema. The ADC of hyperpolarized noble gases depends strongly on the diffusion time (Δ), and ³He ADC has been shown to be anisotropic for Δ ranging from a few milliseconds down to a few hundred microseconds. In this study, the anisotropic nature of ¹²⁹Xe diffusion and its dependence on Δ were investigated both numerically, in a budded cylinder model, and in vivo, in an elastase‐instilled rat model of emphysema. Whole lung longitudinal ADC (D_L) and transverse ADC (D_T) were measured for Δ = 6, 50, and 100 ms at 73.5 mT, and correlated with measurements of the mean linear intercept (L_m) obtained from lung histology. A significant increase (P = 0.0021) in D_T was measured for Δ = 6 ms between the sham (0.0021 ± 0.0005 cm²/s) and elastase‐instilled (0.005 ± 0.001 cm²/s) cohorts, and a strong correlation was measured between D_T (Δ = 6 ms) and L_m, with a Pearson's correlation coefficient of 0.90. This study confirms that ¹²⁹Xe D_T increases correlate with alveolar space enlargement due to elastase instillation in rats. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.