The sequence of the human genome

A 2.91-billion base pair (bp) consensus sequence of the euchromatic portion of the human genome was generated by the whole-genome shotgun sequencing method. The 14.8-billion bp DNA sequence was generated over 9 months from 27,271,853 high-quality sequence reads (5.11-fold coverage of the genome) from both ends of plasmid clones made from the DNA of five individuals. Two assembly strategies-a whole-genome assembly and a regional chromosome assembly-were used, each combining sequence data from Celera and the publicly funded genome effort. The public data were shredded into 550-bp segments to create a 2.9-fold coverage of those genome regions that had been sequenced, without including biases inherent in the cloning and assembly procedure used by the publicly funded group. This brought the effective coverage in the assemblies to eightfold, reducing the number and size of gaps in the final assembly over what would be obtained with 5.11-fold coverage. The two assembly strategies yielded very similar results that largely agree with independent mapping data. The assemblies effectively cover the euchromatic regions of the human chromosomes. More than 90% of the genome is in scaffold assemblies of 100,000 bp or more, and 25% of the genome is in scaffolds of 10 million bp or larger. Analysis of the genome sequence revealed 26,588 protein-encoding transcripts for which there was strong corroborating evidence and an additional approximately 12,000 computationally derived genes with mouse matches or other weak supporting evidence. Although gene-dense clusters are obvious, almost half the genes are dispersed in low G+C sequence separated by large tracts of apparently noncoding sequence. Only 1.1% of the genome is spanned by exons, whereas 24% is in introns, with 75% of the genome being intergenic DNA. Duplications of segmental blocks, ranging in size up to chromosomal lengths, are abundant throughout the genome and reveal a complex evolutionary history. Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems. DNA sequence comparisons between the consensus sequence and publicly funded genome data provided locations of 2.1 million single-nucleotide polymorphisms (SNPs). A random pair of human haploid genomes differed at a rate of 1 bp per 1250 on average, but there was marked heterogeneity in the level of polymorphism across the genome. Less than 1% of all SNPs resulted in variation in proteins, but the task of determining which SNPs have functional consequences remains an open challenge.

The genome sequence of Drosophila melanogaster

The fly Drosophila melanogaster is one of the most intensively studied organisms in biology and serves as a model system for the investigation of many developmental and cellular processes common to higher eukaryotes, including humans. We have determined the nucleotide sequence of nearly all of the approximately 120-megabase euchromatic portion of the Drosophila genome using a whole-genome shotgun sequencing strategy supported by extensive clone-based sequence and a high-quality bacterial artificial chromosome physical map. Efforts are under way to close the remaining gaps; however, the sequence is of sufficient accuracy and contiguity to be declared substantially complete and to support an initial analysis of genome structure and preliminary gene annotation and interpretation. The genome encodes approximately 13,600 genes, somewhat fewer than the smaller Caenorhabditis elegans genome, but with comparable functional diversity.

The selective sphingosine 1-phosphate receptor modulator BAF312 redirects lymphocyte distribution and has species-specific effects on heart rate

BACKGROUND AND PURPOSE

BAF312 is a next-generation sphingosine 1-phosphate (S1P) receptor modulator, selective for S1P₁ and S1P₅ receptors. S1P₁ receptors are essential for lymphocyte egress from lymph nodes and a drug target in immune-mediated diseases. Here, we have characterized the immunomodulatory potential of BAF312 and the S1P receptor-mediated effects on heart rate using preclinical and human data.

EXPERIMENTAL APPROACH

BAF312 was tested in a rat experimental autoimmune encephalomyelitis (EAE) model. Electrophysiological recordings of G-protein-coupled inwardly rectifying potassium (GIRK) channels were carried out in human atrial myocytes. A Phase I multiple-dose trial studied the pharmacokinetics, pharmacodynamics and safety of BAF312 in 48 healthy subjects.

KEY RESULTS

BAF312 effectively suppressed EAE in rats by internalizing S1P₁ receptors, rendering them insensitive to the egress signal from lymph nodes. In healthy volunteers, BAF312 caused preferential decreases in CD4⁺ T cells, T_naïve, T_{central memory} and B cells within 4–6 h. Cell counts returned to normal ranges within a week after stopping treatment, in line with the elimination half-life of BAF312. Despite sparing S1P₃ receptors (associated with bradycardia in mice), BAF312 induced rapid, transient (day 1 only) bradycardia in humans. BAF312-mediated activation of GIRK channels in human atrial myocytes can fully explain the bradycardia.

CONCLUSION AND IMPLICATIONS

This study illustrates species-specific differences in S1P receptor specificity for first-dose cardiac effects. Based on its profound but rapidly reversible inhibition of lymphocyte trafficking, BAF312 may have potential as a treatment for immune-mediated diseases.

Specific layers in aerobically grown microbial granules

AIMS

To determine the optimal size of aerobically grown granules for wastewater treatment by measuring specific layers within the granules.

METHODS AND RESULTS

A variety of biological layers were detected by oligonucleotide probes, specific fluorochromes, and fluorescent microspheres. The channels in the granule matrix penetrated to depths of 900 microm. A layer of obligate anaerobic bacteria was detected at a depth of 800 microm below the granule surface. Dead cells were also observed in the granule interior.

CONCLUSIONS

Aerobically grown granules contained layers of aerobic and anaerobic micro-organisms.

SIGNIFICANCE AND IMPACT OF THE STUDY

The optimal diameter of the aerobic granule is less than 1600 microm. This is twice the distance from the granule surface to the anaerobic layer. This approach can be used to optimize the thickness of other microbial aggregates such as flocs, colonies and biofilms.

Expression of histocompatibility antigens H-2K, -D, and -L is reduced in adenovirus-12-transformed mouse cells and is restored by interferon gamma

Primary mouse cells transformed by adenovirus type 12 (Ad12) expressed negligible amounts of class I antigens H-2K, -D, and -L on the cell surface and were capable of forming tumors in syngeneic animals, whereas cells transformed by Ad5 continued to express class I antigens and were nontumorigenic. Cells from a tumor, generated by injection of Ad12-transformed mouse cells into a syngeneic mouse, also expressed low levels of H-2 antigens, indicating that this phenotype is maintained in vivo. In all Ad12-transformed cells, synthesis of the H-2 heavy chain was not detected whereas the beta 2-microglobulin light chain was synthesized. Furthermore, the level of cytoplasmic H-2 mRNA in the Ad12 lines was greatly reduced. Reduction of H-2 expression is instructed solely by the transforming region of the viral genome, since this repression occurred in cells transformed by a DNA fragment containing only Ad12 E1A and E1B genes. Addition of recombinant murine interferon gamma strongly stimulated expression of class I antigens in the Ad12 transformants as well as in cells from the Ad12 tumor. This result indicates that Ad12 does not preferentially transform cells that are deficient for class I genes and that Ad12 does not mutate the class I genes in cells it transforms. The correlation between tumorigenicity and loss of H-2 expression in Ad12-transformed cells is discussed.

Intercorrelations among plasma high density lipoprotein, obesity and triglycerides in a normal population

The interrelationships among fatness measures, plasma triglycerides and high density lipoproteins (HDL) were examined in 131 normal adult subjects: 38 men aged 27-46, 40 men aged 47-66, 29 women aged 27-46 and 24 women aged 47-66. None of the women were taking estrogens or oral contraceptive medication. The HDL concentration was subdivided into HDL2b, HDL2a and HDL3 by a computerized fitting of the total schlieren pattern to reference schlieren patterns. Anthropometric measures employed included skinfolds at 3 sites. 2 weight/height indices and 2 girth measurements. A high correlation was found among the various fatness measures. These measures were negatively correlated with total HDL, reflecting the negative correlation between fatness measures and HDL2 (as the sum of HDL2a and 2b). Fatness measures showed no relationship to HDL3. There was also an inverse correlation between triglyceride concentration and HDL2. No particular fatness measure was better than any other for demonstrating the inverse correlation with HDL but multiple correlations using all of the measures of obesity improved the correlations. Partial correlations controlling for fatness did not reduce any of the significant correlations between triglycerides and HDL2 to insignificance. The weak correlation between fatness and triglycerides was reduced to insignificance when controlled for HDL2.

Sequence and variability of the 5.8S and 26S rRNA genes of Pneumocystis carinii

The sequence of the coding region of the rRNA operon of rat-derived Pneumocystis carinii has been completed, including the genes for 5.8S and 26S rRNA. These genes show homology to the rRNA genes of yeast, and an apparent group I self-splicing intron is present in the 26S rRNA gene. Like a similar intron in the 16S rRNA gene, this intron is in a phylogenetically conserved region. Variation in the 26S rRNA sequence was noted between P. carinii organisms isolated from two different sources.

Near-infrared spectroscopic measurement of physiological glucose levels in variable matrices of protein and triglycerides

Selective calibration models are generated for glucose over the 1-20 nM concentration range by use of partial least-squares regression analysis of near-infrared spectra from 5000 to 4000 cm-1. Two spectral data sets are used to simulate triglyceride and protein variations in clinical samples. Triacetin is used in one data set to simulate variations in triglyceride levels, and bovine serum albumin (BSA) is used in the second data set to simulate variations in blood protein levels. Although these matrix components possess strong absorption bands that overlap and overshadow the absorption bands of glucose, successful calibration models can be generated with no evidence of prediction bias caused by the different levels of the matrix components. Furthermore, the benefits of using digital Fourier filtering as a preprocessing step are evaluated in terms of calibration performance. The resulting calibration models provide standard errors of prediction of 0.5 and 0.2 mM in triacetin and BSA matrices, respectively. Accurate glucose predictions are demonstrated from spectra that correspond to protein concentrations not present in the calibration data set. Lastly, digital Fourier filtering alone is shown to have only limited ability to isolate glucose signals from those of BSA and triacetin due to similarities in the widths of the absorption bands of the three species.

Fiber-optic enzyme biosensor for direct determination of organophosphate nerve agents

A fiber-optic enzyme biosensor for the direct measurement of organophosphate nerve agents was developed. The basic element of this biosensor is organophosphorus hydrolase immobilized on a nylon membrane and attached to the common end of a bifurcated optical fiber bundle. The enzyme catalyzes the hydrolysis of organophosphate compounds to form stoichiometric amounts of chromophoric products that absorb light at specific wavelengths. The back-scattered radiation of the specific incident radiation was measured using a photomultiplier detector and correlated to the organophosphate concentration. The effects of buffer pH, temperature, and the units of enzyme immobilized on the steady-state and kinetic response of the biosensor were investigated to optimize the operating conditions for the fiber-optic enzyme biosensor. These conditions were then used to measure parathion, paraoxon, and coumaphos selectively without interference from carbamates and triazines. Concentrations as low as 2 microM can be measured in less than 2 min using the kinetic response. When stored in buffer at 4 degreesC the biosensor shows long-term stability.

Risk factors for male breast cancer in Canada, 1994-1998

Relatively little attention has been paid to the aetiology of male breast cancer and the current understanding of female breast cancer, primarily related to reproductive events, cannot be readily transferred to understanding the cancer in males. However, since male breast cancer occurs in the absence of factors related to childbearing and menstruation, its aetiology may provide special insights into the causes of breast cancer in women. We examined lifestyle risk factors for male breast cancer as part of a Canadian, multi-site, population-based, case-control study. Eighty-one newly diagnosed, histologically confirmed cases and 1905 male controls aged 42-74 were analysed using unconditional logistic regression. Increased risks were found for men with a mother or sister with breast cancer (adjusted odds ratio (OR) 3.65, 95% confidence interval (95% CI) 1.62-8.19). Higher physical activity levels (moderate, and strenuous recreational plus occupational) were associated with a decreased risk of male breast cancer (highest quartile, adjusted OR 0.48, 95% CI 0.26-0.91). Similarly, higher risks were associated with higher weight 2 years before interview (2.19, 95% CI 1.08-4.43), maximum weight (OR 2.66) and higher body mass index (OR 1.60). Higher vegetable consumption and coffee consumption were associated with decreased risk, whereas higher beta-carotene, vitamin E and calcium supplementation were associated with statistically significant increased risk. The small number of cases and multiple comparisons preclude strong conclusions, but our study is consistent with studies suggesting obesity and family history increase risk, and physical activity decreases risk of breast cancer.

Specific interactions with TBP and TFIIB in vitro suggest that 14-3-3 proteins may participate in the regulation of transcription when part of a DNA binding complex

The 14-3-3 family of multifunctional proteins is highly conserved among animals, plants, and yeast. Several studies have shown that these proteins are associated with a G-box DNA binding complex and are present in the nucleus in several plant and animal species. In this study, 14-3-3 proteins are shown to bind the TATA box binding protein (TBP), transcription factor IIB (TFIIB), and the human TBP-associated factor hTAF(II)32 in vitro but not hTAF(II)55. The interactions with TBP and TFIIB were highly specific, requiring amino acid residues in the box 1 domain of the 14-3-3 protein. These interactions do not require formation of the 14-3-3 dimer and are not dependent on known 14-3-3 recognition motifs containing phosphoserine. The 14-3-3-TFIIB interaction appears to occur within the same domain of TFIIB that binds the human herpes simplex virus transcriptional activator VP16, because VP16 and 14-3-3 were able to compete for interaction with TFIIB in vitro. In a plant transient expression system, 14-3-3 was able to activate GAL4-dependent beta-glucuronidase reporter gene expression at low levels when translationally fused with the GAL4 DNA binding domain. The in vitro binding with general transcription factors TBP and TFIIB together with its nuclear location provide evidence supporting a role for 14-3-3 proteins as transcriptional activators or coactivators when part of a DNA binding complex.

Expression of H-2, laminin and SV40 T and TASA on differentiation of transformed murine teratocarcinoma cells

Murine embryonal carcinoma cells (ECCs) do not express antigens of the major histocompatibility complex (H-2), but do express cell-surface molecules shared with early embryos. ECCs are also characterized by their insusceptibility to infection by various oncogenic viruses, and their ability to differentiate into a variety of adult cell types. Differentiation of ECCs in vitro can occur spontaneously or can be induced. On exposure to retinoic acid the ECC line F9 (ref. 13) differentiates into cells which have the characteristics of parietal endoderm. When ECCs are exposed to simian virus 40 (SV40), the SV40 tumour (T) antigen is not expressed, although the virus genome reaches the nucleus, and a primary transcript of the SV40 A gene is made. However, following exposure to retinoic acid, the differentiated cells, like most mouse somatic cells, are susceptible to SV40 abortive infection and synthesize large T and small t antigens. To monitor the molecular events associated with the expression of the SV40 A gene on differentiation, we have constructed an ECC line (F9 12-1) containing a single integrated copy of the SV40 genome. This was accomplished by introducing a recombinant plasmid consisting of pBR322 linked to the herpes simplex type 1 thymidine kinase gene and SV40 genome into a thymidine kinase-deficient F9 cell line. We report here that in F9 12-1 cells exposed to retinoic acid, synthesis of the SV40 A gene product(s), T and tumour-associated specific antigens (TASA), parallels the appearance of the normal hallmarks of differentiation in this cell line, H-2 antigens and the basement membrane protein laminin.

Evidence for a phylogenetic connection between Coccidioides immitis and Uncinocarpus reesii (Onygenaceae)

Coccidioides immitis is an anomaly amongst the human systemic fungal pathogens. Its unique parasitic cycle has contributed to confusion over its taxonomy. Early investigators mistakenly suggested that the pathogen is a protist, while others agreed it to be a fungus but placed it in four different divisions of the Eumycota. The taxonomy of C. immitis is still unresolved. Ultrastructural examinations of its parasitic and saprobic phases have revealed features that are diagnostic of the ascomycetous fungi. Moreover, striking similarities between the kind of asexual reproduction (i.e. arthroconidium formation) of this pathogen and certain anamorphic and teleomorphic members of the genus Malbranchea have suggested a close relationship. Teleomorphs of these Malbranchea species are members of the Onygenaceae (Order, Onygenales). This family also includes teleomorphs of two human respiratory pathogens, Histoplasma capsulatum and Blastomyces dermatitidis. Although the 18S rRNA gene sequences (1713 bp) of these two pathogenic forms differ from that of C. immitis by only 35 and 33 substitutions, respectively, their mode of conidiogenesis is characterized by production of solitary aleurioconidia rather than alternate arthroconidia. In this study we have used characters derived from biochemical, immunological and molecular analyses to compare relatedness between C. immitis, H. capsulatum, B. dermatitidis, and six non-pathogenic species of Malbranchea (the Malbranchea states of Uncinocarpus reesii and Auxarthron zuffianum, as well as M. albolutea, M. dendritica, M. filamentosa and M. gypsea). Evidence is presented which supports inclusion of C. immitis in the Onygenaceae, and indicates that a close phylogenetic relationship exists between the Malbranchea state of U. reesii and this respiratory pathogen.

The effect of hydraulic retention time on the stability of aerobically grown microbial granules

AIMS

The aim of this study is to evaluate the effect of hydraulic retention time (HRT) on the development of aerobically grown microbial granules.

METHODS AND RESULTS

Five column-shaped sequential aerobic sludge blanket reactors (SASBRs) were seeded with aerobically grown microbial granules and operated in a cyclic mode at different HRTs. At the shortest HRT of 1 h, the strong hydraulic pressure triggered biomass washout and led to reactor failure. At the longest HRT of 24 h, which represented the weakest hydraulic selection in this study, aerobic granules were gradually substituted by bioflocs because of the lower frequency of volumetric exchange. Within the optimum range of HRTs from 2 to 12 h, however, aerobic granules became stabilized in the presence of adequate hydraulic selection in the reactors, with good mixed liquor volatile suspended solids (MLVSS) retention, high volumetric chemical oxygen demand (COD) removal, low sludge volume index (SVI) values, good effluent quality, low sludge production rate, stronger and more compact structures, high cell hydrophobicity and high ratios of extracellular polysaccharides (PS) to extracellular proteins (PN).

CONCLUSIONS

HRTs between 2 and 12 h provided the hydraulic selection pressures favourable for the formation and maintenance of stable aerobic granules with good settleability and activity.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first systematic study on the effect of HRT on heterotrophic aerobic granules. The results of the investigation are useful in understanding how aerobic granules can be applied for wastewater treatment.

Mining time dependency patterns in clinical pathways

Clinical pathways are widely adopted by many large hospitals around the world in order to provide high-quality patient treatment and reduce the length of hospital stay of each patient. The development of clinical pathways is a lengthy process, and may require the collaboration among physicians, nurses, and staffs in a hospital. However, the individual differences cause great variances in the execution of clinical pathways. It calls for a more dynamic and adaptive process to improve the performance of clinical pathways. This paper reports a data mining technique we have developed to discover the time dependency pattern of clinical pathways for managing brain stroke. The mining of time dependency pattern is to discover patterns of process execution sequences and to identify the dependent relation between activities in a majority of cases. By obtaining the time dependency patterns, we can predict the paths for new patients when he/she is admitted into a hospital; in turn, the health care procedure will be more effective and efficient.

Favoring Trauma as an Etiological Factor in Denture Stomatitis

The etiology of denture stomatitis remains controversial. Trauma due to unstable dentures has been suggested as an etiological factor. Therefore, we tested the hypothesis that the prevalence of denture stomatitis is reduced when mandibular dentures are stabilized by implants. Data were collected at a one-year follow-up from 173 edentulous elders who had randomly received mandibular implant overdentures or conventional dentures. The diagnosis of denture stomatitis was determined according to the Newton classification. Elders wearing conventional dentures were almost 5 times more likely to have denture stomatitis than those wearing mandibular two-implant overdentures ( P < 0.0001, Fisher’s exact test). Adjusted odds ratios showed that only the type of the prosthesis (AOR = 4.54, 95% CI 2.20 to 9.40) and nocturnal wear (AOR = 3.03, 95% CI 1.24 to 7.40) predict the frequency of denture stomatitis. Thus, implant overdentures may reduce oral mucosal trauma and control denture stomatitis.

Rapid amplification of complementary DNA from small amounts of unfractionated RNA

We have combined, in a rapid and straightforward manner, the synthesis and subsequent amplification of individual cDNA sequences from microgram quantities of unfractionated total RNA. Taq1 polymerase, a thermostable DNA polymerase, and Moloney murine leukemia virus (MMLV) reverse transcriptase share similar buffer conditions; these reactions can be performed sequentially, in a single tube, without the need for purification or changes of buffer after the synthesis of cDNA. In this way, nonspecific losses of material are minimized and the required number of cells is reduced. Cell numbers, particularly from human tissues, can be limiting; the requirement for only small amounts of unfractionated RNA makes possible the isolation and characterization of cDNAs from biological materials available in limited quantities. As a demonstration system, we report the rapid synthesis and amplification of cDNA sequences corresponding to the first exon of human immunoglobulin E (IgE). MMLV reverse transcriptase is used with specific (i.e., IgE) or generic (i.e., oligo-[dT(12-18)]) oligomers to prime first strand cDNA synthesis from unfractionated RNA isolated from a human myeloma line, U-266. The necessary primers, deoxynucleotides and Taq1 polymerase, required for second strand cDNA synthesis and the subsequent logarithmic amplification process, are then added to the reaction mixture. This technique provides a useful means of characterizing expressed and processed gene transcripts.

Molecular and biochemical characterization of a Coccidioides immitis-specific antigen

Results of earlier investigations have indicated that the saprobic phase of Coccidioides immitis produces a heat-stable, 19-kDa antigen with serine proteinase activity which has been suggested to be specific for this pathogenic fungus. In the present study we have determined the N-terminal and partial internal amino acid sequences of the purified, 19-kDa antigen, cloned the gene which encodes this polypeptide, and confirmed that the secreted proteinase is a Coccidioides-specific antigen (CS-Ag). Both the genomic and cDNA sequences are reported and reveal that the csa gene which encodes this antigen has no introns. A 543-bp open reading frame encodes a 181-amino-acid-containing protein with a predicted molecular mass of 19.8 kDa and an isoelectric point of 8.3. The csa gene was localized on chromosome I of three representative C. immitis clinical isolates on the basis of Southern hybridizations. Expression of the csa gene in Escherichia coli using the pET21a plasmid vector yielded a recombinant protein that was recognized in immunoblot assays by antibody raised to the purified 19-kDa CS-Ag. Secretion of the native antigen is suggested to occur by cleavage of a putative 23-residue signal peptide. The native CS-Ag showed a low degree of glycosylation. Analysis of the carbohydrate composition of the CS-Ag revealed xylose, mannose, galactose, and glucose. However, the purified antigen showed no affinity for concanavalin A. A PCR method with specificity and high sensitivity for detection of C. immitis genomic DNA, using a pair of synthetic oligonucleotide primers whose sequences were based on that of the csa gene, was developed. A 520-bp product was amplified only when C. immitis genomic DNA was used as the template. The lower limits of DNA detection using this PCR method were 1 pg of C. immitis genomic DNA by ethidium bromide staining and 100 fg after Southern hybridization. The csa gene-based PCR method for detection of C. immitis DNA is useful for culture identification and may have clinical applications for the diagnosis of coccidioidal infections.

A permanent human cell line (EA.hy926) preserves the characteristics of endothelin converting enzyme from primary human umbilical vein endothelial cells

Purification of endothelin converting enzyme (ECE) from endothelial cells has been hindered by the difficulty in obtaining primary endothelial cells in large quantity. We therefore tested transformed human umbilical vein endothelial cells (EA.hy926) for ECE activity. Our data clearly demonstrate that this transformed cell line preserves the ECE properties of the primary cell line. These include: (i) one sharp activity optimum at neutral pH; (ii) characteristics typical of a metalloprotease; (iii) IC50 value for phosphoramidon of 1.8 microM (2.7 microM for HUVEC); (iv) no inhibition by captopril and thiorphan, inhibitors of angiotensin converting enzyme and neutral endopeptidase 24.11. The enzyme showed a substrate specificity for big ET-1:big ET-2:big ET-3 in a ratio of 40:2.5:1. This report presents evidence that a permanent human endothelial cell line, EA.hy926, preserves the ECE activity of HUVEC and is useful for the study of ECE and its regulation of ET-1 production.

Depletion of CD8+ cells in human thymic medulla results in selective immune deficiency

CD8 molecules expressed on the surface of a subset of T cells participate in the selection of class I MHC antigen-restricted T cells in the thymus, and in MHC-restricted immune responses of mature class I MHC antigen-restricted T cells. Here we describe an immune-deficient patient with lack of CD8+ peripheral blood cells. The patient presented with Pneumocystis carinii pneumonia and was unable to reject an allogeneic skin graft, but had normal primary and secondary antibody responses. Examination of the patient's thymus revealed that the loss of CD8+ cells occurred during intrathymic differentiation: the patient's immature cortical thymocytes included both CD4+ and CD8+ cells while the mature medullary cells expressed the CD4 but not the CD8 protein on their surface. Northern blot and polymerase chain reaction analyses revealed the presence of CD8 alpha and beta mRNA in the patient's thymus but not in the peripheral blood. Both class I MHC antigen expression and the expressed TCR V beta repertoire are normal in this patient. These data are consistent with an impaired selection of CD8+ cells in the patient's thymus and support the role of the CD8 surface protein in thymic selection previously characterized in genetically manipulated and inbred mice.

Molecular determinants of cardiac Ca2+ channel pharmacology. Subunit requirement for the high affinity and allosteric regulation of dihydropyridine binding

Cardiac L-type Ca2+ channels are multisubunit complexes composed of alpha 1C, alpha 2 delta, and beta 2 subunits. We tested the roles of these subunits in forming a functional complex by characterizing the effects of subunit composition on dihydropyridine binding, its allosteric regulation, and the ability of dihydropyridines to inhibit channel activity. Transfection of COS.M6 cells with cardiac alpha 1C-a (alpha 1) led to the appearance of dihydropyridine ([3H]PN200-110) binding which was increased by coexpression of cardiac beta 2a (beta), alpha 2 delta a (alpha 2), and the skeletal muscle gamma. Maximum binding was achieved when cells expressed alpha 1, beta, and alpha 2. Cells transfected with alpha 1 and beta had a binding affinity that was 5-10-fold lower than that observed in cardiac membranes. Coexpression of alpha 2 normalized this affinity. (-)-D600 and diltiazem both partially inhibited PN200-100 binding to cardiac microsomes, but stimulated binding in cells transfected with alpha 1 and beta. Again, coexpression of alpha 2 normalized this allosteric regulation. Therefore coexpression of alpha 1 beta and alpha 2 completely reconstituted high affinity dihydropyridine binding and its allosteric regulation as observed in cardiac membranes. Skeletal muscle gamma was not required for this reconstitution. Expression in Xenopus oocytes demonstrated that coexpression of alpha 2 with alpha 1 beta increased the potency and maximum extent of block of Ca2+ channel currents by nisoldipine, a dihydropyridine Ca2+ channel antagonist. Our results demonstrate that alpha 2 subunits are essential components of the cardiac L-type Ca2+ channel and predict a minimum subunit composition of alpha 1C beta 2 alpha 2 delta for this channel.

Measurement of Blood Thiamine Metabolites for Alzheimer's Disease Diagnosis

Background

Brain glucose hypometabolism is an invariant feature and has significant diagnostic value for Alzheimer's disease. Thiamine diphosphate (TDP) is a critical coenzyme for glucose metabolism and significantly reduced in brain and blood samples of patients with Alzheimer's disease (AD).

Aims

To explore the diagnostic value of the measurement of blood thiamine metabolites for AD.

Methods

Blood TDP, thiamine monophosphate, and thiamine levels were detected using high performance liquid chromatography (HPLC). The study included the exploration and validation phases. In the exploration phase, the samples of 338 control subjects and 43 AD patients were utilized to establish the models for AD diagnosis assayed by receiver operating characteristic (ROC) curve, including the variable γ that represents the best combination of thiamine metabolites and age to predict the possibility of AD. In the validation phase, the values of models were further tested for AD diagnosis using samples of 861 control subjects, 81 AD patients, 70 vascular dementia patients, and 13 frontotemporal dementia patients.

Results

TDP and the γ exhibited significant and consistent values for AD diagnosis in both exploration and validation phases. TDP had 0.843 and 0.837 of the areas under ROC curve (AUCs), 77.4% and 81.5% of sensitivities, and 78.1% and 77.2% of specificities respectively in the exploration and validation phases. The γ had 0.938 and 0.910 of AUCs, 81.4% and 80.2% of sensitivities, and 90.5% and 87.2% of specificities respectively in the exploration and validation phases. TDP and the γ can effectively distinguish AD from vascular dementia (64.3% for TDP, 67.1% for γ) and frontotemporal dementia (84.6% for TDP, 100.0% for γ).

Interpretation.

The measurement of blood thiamine metabolites by HPLC is an ideal diagnostic test for AD with inexpensive, easy to perform, noninvasive merits.

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The measurement of blood thiamine metabolites by HPLC as a promising biomarker test for Alzheimer’s disease diagnosis.

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This test is inexpensive, easy to perform and noninvasive which meets the criteria of ideal biomarker for Alzheimer’s disease.

The disturbance of brain glucose metabolism is an invariant feature and has significant diagnostic value for Alzheimer's disease. Thiamine diphosphate, one of thiamine metabolites, is a critical coenzyme for three key enzymes of glucose metabolism and significantly reduced in brain and blood samples of a small number of Alzheimer's disease patients. Our study demonstrates that the measurement of blood thiamine metabolites, manifested as thiamine diphosphate level and the variable γ representing the best combination of thiamine metabolites and age, exhibits excellent value for Alzheimer's disease diagnosis with inexpensive, easy to perform, noninvasive merits.