Down syndrome in association with features of the androgen insensitivity syndrome.

Three cases of Down syndrome (DS) are reported in association with features of the androgen insensitivity syndrome (AIS). All were 47, XY, +21 and reared as females. One case had a normal female phenotype, and two cases showed minimal clitoromegaly and labial fusion. Minor genital underdevelopment has been reported as common in males with DS; however, AIS has not previously been associated with DS. Androgen binding studies in genital skin fibroblasts were normal in two cases and in the 46,XY brother of the third who has perineal hypospadias. Mutation screening of the androgen receptor (AR) gene by PCR-SSCP was normal in all cases. Normal androgen binding and the absence of an identified mutation in the coding region of the AR gene is very unusual in AIS, particularly in the complete form. This finding suggests the operation of hitherto unrecognised genes on chromosome 21 with a role in androgen response and sex differentiation.     

An Association Between a Microsatellite Polymorphism at the DRD5 Gene and the Liability to Substance Abuse: Pilot Study

We have conducted a population-based association study of substance abuse and a microsatellite at the dopamine D5 receptor locus (DRD5) in a sample of European–American males and females with substance dependence (SA) or without any psychiatric disorder. Overrepresentation of the most frequent allele (148 bp) was found in males in the SA group (OR = 2.2, P= .02); this finding was reproduced in females (OR = 5.4, p< .001). The difference in the frequencies of this allele between SA males and SA females was statistically significant. The genotype coded in accordance with the dose of this allele correlated with substance abuse liability in males and females (stronger in females) and with novelty seeking in females. There was no evidence of correlation between the genotypes of spouses that could be induced by assortative mating for the liability to substance abuse. The data suggest that the DRD5 locus is involved in the variation and sex dimorphism of substance abuse liability.CEDAR is a consortium between St. Francis Medical Center and the University of Pittsburgh.     

Identification of glycosylation sites in the SU component of the Avian Sarcoma/Leukosis virus Envelope Glycoprotein (Subgroup A) by mass spectrometry

We used enzymatic digestion and mass spectrometry to identify the sites of glycosylation on the SU component of the Avian Sarcoma/Leukosis virus (ASLV) Envelope Glycoprotein (Subgroup A). The analysis was done with an SU(A)-rIgG fusion protein that binds the cognate receptor (Tva) specifically. PNGase F removed all the carbohydrate from the SU(A)-rIgG fusion. PNGase F is specific for N-linked carbohydrates; this shows that all the carbohydrate on SU(A) is N-linked. There are 10 modified aspargines in SU(A) (N17, N59, N80, N97, N117, N196, N230, N246, N254, and N330). All conform to the consensus site for N-linked glycosylation NXS/T. There is one potential glycosylation site (N236) that is not modified. Removing most of the carbohydrate from the mature SU(A)-rIgG by PNGase F treatment greatly reduces the ability of the protein to bind Tva, suggesting that carbohydrate may play a direct role in receptor binding.     

Dielectrophoretic assay of bacterial resistance to antibiotics

The dielectrophoretic collection spectra of antibiotic-sensitive and antibiotic-resistant strains of Staphylococcus epidermidis have been determined. These indicate that in the absence of antibiotic treatment there is a strong similarity between the dielectric properties of sensitive and resistant strains, and that there is a significant difference between the sensitive strains before and after treatment with the antibiotic streptomycin after 24 h exposure. This method offers possibilities for the assessment of bacterial resistance to antibiotics.     

The cholera toxin B subunit is a mucosal adjuvant for oral tolerance induction in type 1 diabetes

When conjugated to various proteins, the nontoxic B-chain of cholera toxin (CTB) significantly increases the ability of these proteins to induce immunological tolerance after oral administration. Here, we investigated if a nonconjugated form of CTB enhances the induction of immune tolerance after oral insulin administration. Induction of immunological tolerance was studied after oral administration of insulin preparations in three mouse models; an insulin/ovalbumin coimmunization model, a model of virus-induced diabetes in transgenic RIP-LCMV-NP mice and in nonobese diabetic (NOD) mice serving as a model of spontaneous diabetes. In the immunization model, we demonstrate that mixing with CTB increases the tolerogenic potential of insulin, approximately 10 fold. Titration of the CTB concentration in this system revealed that an insulin : CTB ratio of 100 : 1 was optimal for the induction of bystander suppression. Further studies revealed that this insulin : CTB ratio also was optimal for the prevention of diabetes in a virus-induced, transgenic diabetes model. In addition, the administration of this optimal insulin-CTB preparation significantly prevented the onset of diabetes in old NOD mice with established islet infiltration. The data presented here demonstrate that CTB, even in its unconjugated form, functions as a mucosal adjuvant, increasing the specific tolerogenic effect of oral insulin.     

Immunological heterogeneity of autoreactive T lymphocytes against the nicotinic acetylcholine receptor in myasthenic patients

The response of human T lymphocytes against the nicotinic acetylcholine receptor (AChR) was studied in five patients with myasthenia gravis (MG) and in six healthy donors using either native Torpedo AChR or recombinant protein derived from the mammalian AChR α subunit (X4, residues 6–216 of mouse AChR α subunit). The present study demonstrates that (a) AChR-specific T helper cell lines can be generated from MG patients [either from peripheral blood lymphocytes (PBL) or from thymocytes] as well as from PBL of normal controls, (b) lymphocytes from MG patients, but not from controls, recognize the mammalian AChR but not the Torpedo receptor, (c) in humans, the HLA-DR2-associated T cell epitope is probably located in the region of residues 162–216 of the AChR α subunit and (d) there is a considerable heterogeneity of autoreactive T cell responses: (i) Tcell lines from different HLA-type donors have distinct epitope profiles; (ii) the epitope specificity of the PBL-derived T cell line is different from that of the thymocyte-derived line; (iii) the epitope specificities of patient-derived T cell lines are different from those generated from normal controls who share the same HLA phenotype.     

Comparative analysis of the polycystic kidney disease 1 (PKD1) gene reveals an integral membrane glycoprotein with multiple evolutionary conserved domains

PKD1 is the major locus of the common genetic disorder autosomal dominant polycystic kidney disease (ADPKD). Analysis of the predicted protein sequence of the human PKD1 gene, polycystin, shows a large molecule with a unique arrangement of extracellular domains and multiple putative transmembrane regions. The precise function of polycystin remains unclear with a paucity of mutations to define key structural and functional domains. To refine the structure of this protein we have cloned the genomic region encoding the Fugu PKD1 gene. Fugu PKD1 spans 36 kb of genomic DNA and has greater complexity with 54 exons compared with 46 in man. Comparative analysis of the predicted protein sequences shows a lower level of homology than in similar studies with identity of 40 and 59% similarity. However key structural motifs including leucine rich repeats (LRR), a C-type lectin and LDL-A like domains and 16 PKD repeats are maintained. A region of homology with the sea urchin REJ protein was also confirmed in Fugu but found to extend over 1000 amino acids. Several highly conserved intra- and extra- cellular regions, with no known sequence homologies, that are likely to be of functional importance were detected. The likely structure of the membrane associated region has been refined with similarity to the PKD2 protein and voltage gated Ca2+ and Na+ channels highlighted over part of this area. The overall protein structure has therefore been clarified and this comparative analysis derived structure will form the basis for the functional study of polycystin and its individual domains.      

Molecular pathology of prostate cancer

The molecular pathology of prostate cancer is complex; not only are multiple genes involved in its pathogenesis, but additional environmental factors such as diet and inflammation are also involved. The exhaustive research into prostate cancer to date has demonstrated a complex interaction of multiple genes and environmental factors, some of which may be more important in individual prostate cancer cases. This is an exciting era, with the emergence of new investigative tools such as DNA microarray technology and the application of the field of proteomics to the study of human cancers. Knowledge of genetic changes underlying the initiation, development, and progression of prostate cancer is accumulating rapidly. With increasing knowledge, it may be possible to distinguish indolent from aggressive prostate tumours by molecular fingerprinting. This review discusses the most consistently reported molecular pathological findings in hereditary and sporadic prostate cancer, together with new concepts and technologies.