Cytogenetic study of mentally retarded children in Taipei

560 blood samples collected from mentally retarded children in Taipei were karyotypically analyzed for the incidence of fragile X and other chromosome abnormalities. The fragile site at Xq27.3 was observed in 18 patients (3.21%), 11 males and 7 females, out of the 560 blood cultures using M medium. Down syndrome (6.25%), 24 males and 11 females, was the other major category of abnormality. Other abnormalities, including inversion, translocation, deletion, duplication, ring as well as an extra marker chromosome were observed. The overall incidence of chromosomal abnormalities in these children was 14.82%.     

Baseline and sodium arsenite-induced sister chromatid exchanges in cultured lymphocytes from patients with Blackfoot disease and healthy persons

Summary A significantly higher frequency of baseline sister chromatid exchange (SCE) was found in the cultured lymphocytes of 13 Blackfoot disease patients (BFP) in comparison with that of healthy persons (HP). Twelve of these BFP consumed well water containing a high concentration of arsenic for 15 years or longer and had switched to drinking tap water 12 years before the time of this study. Sodium arsenite was found to be effective in increasing the SCE frequency and delaying the cell growth of the lymphocytes from both BFP and HP. However, the SCE increment induced by sodium arsenite as well as the progression of the cell divisions in the cultured lymphocytes showed no significant difference between BFP and HP.     

Amino acid sequence of bovine neurophysin-II: a reinvestigation.

The entire amino acid sequence of bovine neurophysin-II has been redetermined by manual Edman degradation of tryptic peptides obtained from performic acid-oxidized neurophysin. Electrophoretically homogeneous bovine neurophysin-II was found to be a mixture of two species of protein molecules both containing 95 amino acid residues. The only difference between the two species of the neurophysin molecules is a single amino acid substitution at residue 89. Of the bovine neurophysin-II used in this work 70% of the protein material contained valine and 30% contained isoleucine at residue 89 in their sequences. The redetermined sequences of bovine neurophysin-II shown in Fig. 2 differ substantially from the reported sequence of bovine neurophysin-II but resemble closely that of porcine neurophysin-I and ovine neurophysin-III (Fig. 3).     

Neuronal LR11 Expression Does Not Differentiate between Clinically-Defined Alzheimer's Disease and Control Brains

Alzheimer's disease (AD) is the leading cause of dementia in the elderly. Because the pathological changes underlying this disease can begin decades prior to the onset of cognitive impairment, identifying the earliest events in the AD pathological cascade has critical implications for both the diagnosis and treatment of this disease. We previously reported that compared to autopsy confirmed healthy control brain, expression of LR11 (or SorLA) is markedly reduced in AD brain as well as in a subset of people with mild cognitive impairment (MCI), a prodromal clinical stage of AD. Recent studies of the LR11 gene SORL1 have suggested that the association between SORL1 single nucleotide polymorphisms (SNPs) and AD risk may not be universal. Therefore, we sought to confirm our earlier findings in a population chosen solely based on clinical criteria, as in most genetic studies. Quantitative immunohistochemistry was used to measure LR11 expression in 43 cases from the Religious Orders Study that were chosen based on a final pre-mortem clinical diagnosis of MCI, mild/moderate AD or no cognitive impairment (NCI). LR11 expression was highly variable in all three diagnostic groups, with no significant group differences. Low LR11 cases were identified using the lowest tertile of LR11 expression observed across all cases as a threshold. Contrary to previous reports, low LR11 expression was found in only 29% of AD cases. A similar proportion of both the MCI and NCI cases also displayed low LR11 expression. AD-associated lesions were present in the majority of cases regardless of diagnostic group, although we found no association between LR11 levels and pathological variables. These findings suggest that the relationship between LR11 expression and the development of AD may be more complicated than originally believed.     

Comparison of 5' region sequences of human and rabbit phosphofructokinase genes

A phosphofructokinase gene was screened and cloned from a human genomic library prepared in the lambda EMBL4 phage vector. DNA sequencing shows that the first exon of this human phosphofructokinase gene is identical in length and highly homologous in sequence to that of a rabbit phosphofructokinase gene. Two amino acid replacements are indicated, an Arg----Lys and a Val----Ile at positions 9 and 13, respectively. Eleven base substitutions, 8 of them silent, are identified. Surprisingly, at ten of these sites, complete bias for A's and T's in the human gene and C's and G's in the rabbit gene are seen. Strong conservation is also observed in the 5' untranslated region and for the first 15 base pairs in the intron. All the nine variant nucleotides in these regions are, again, A's and T's in the human gene and G's and C's in the rabbit gene. The unit evolutionary period of change between the first exon of rabbit and human phosphofructokinase genes is estimated as 2.3 million years at silent sites and 15.6 million years at replacement sites.     

Cell‐free synthesis of functional aquaporin Z in synthetic liposomes

The challenges involved in producing sufficient quantities of aquaporins for precise biophysical characterization have limited our knowledge of this important class of molecules. This article describes a cell‐free protein synthesis method for producing high concentrations of the E. coli water transporter, aquaporin Z (AqpZ), in synthetic liposomes. To our knowledge, this is the first report of in vitro synthesis of a membrane protein directly into synthetic liposomes with verified function, (i.e., transport activity and selectivity). Titration of DOPC lipid vesicles added to the cell‐free reaction show that production yields of active AqpZ are dependent on the concentration of DOPC lipid vesicles added to the cell‐free reaction, with 224 ± 24 lipids required per aquaporin monomer. Supplementation of the signal recognition particle receptor (FtsY) to the cell‐free reaction increases production of vesicle‐associated AqpZ but not active AqpZ. Cell‐free reactions using 7 mg/mL lipids that were not supplemented with FtsY produced 507 ± 11 µg/mL of vesicle‐associated AqpZ that exhibited a specific water transport activity of (2.2 ± 0.3) × 10^?14 cm³ s^?1 monomer^?1. Proteinase K protection, activation energy determination, and selectivity against glycerol and urea transport also confirmed the production of correctly folded AqpZ. This technique is capable of producing milligram quantities of aquaporin that can be readily assayed for function, facilitating biophysical characterization and high‐throughput analysis. Biotechnol. Bioeng. 2009; 104: 40–49 © 2009 Wiley Periodicals, Inc.     

Down regulation of trk but not p75NTR gene expression in single cholinergic basal forebrain neurons mark the progression of Alzheimer's disease

Dysfunction of cholinergic basal forebrain (CBF) neurons of the nucleus basalis (NB) is a cardinal feature of Alzheimer's disease (AD) and correlates with cognitive decline. Survival of CBF neurons depends upon binding of nerve growth factor (NGF) with high-affinity (trkA) and low-affinity (p75(NTR)) neurotrophin receptors produced within CBF neurons. Since trkA and p75(NTR) protein levels are reduced within CBF neurons of people with mild cognitive impairment (MCI) and mild AD, trkA and/or p75(NTR) gene expression deficits may drive NB degeneration. Using single cell expression profiling methods coupled with custom-designed cDNA arrays and validation with real-time quantitative PCR (qPCR) and in situ hybridization, individual cholinergic NB neurons displayed a significant down regulation of trkA, trkB, and trkC expression during the progression of AD. An intermediate reduction was observed in MCI, with the greatest decrement in mild to moderate AD as compared to controls. Importantly, trk down regulation is associated with cognitive decline measured by the Global Cognitive Score (GCS) and the Mini-Mental State Examination (MMSE). In contrast, there is a lack of regulation of p75(NTR) expression. Thus, trk defects may be a molecular marker for the transition from no cognitive impairment (NCI) to MCI, and from MCI to frank AD.