Single base mutations in the human androgen receptor gene causing complete androgen insensitivity: rapid detection by a modified denaturing gradient gel electrophoresis technique.

Mutations of the human androgen receptor (AR) gene impair normal sexual differentiation and development in karyotypic males, resulting in a spectrum of external genital phenotypes ranging from complete female to nearly complete male. Identification and characterization of these mutations can provide valuable information regarding the functional importance of specific amino acids of the AR. To screen for point mutations in the AR gene underlying the phenotypic abnormalities in the androgen insensitivity syndrome (AIS), the eight exons of the AR gene were amplified from genomic DNA using the polymerase chain reaction (PCR) and analyzed by denaturing gradient gel electrophoresis. A computer program, MELTMAP, was used to identify optimum sequences for denaturing gradient gel electrophoresis, and mutation detection sensitivity was enhanced by forming heteroduplexes between control and subject PCR products to create base mismatches. In seven families with complete AIS, single base mutations were found in the region of the AR gene encoding the steroid-binding domain of the receptor. The mutations that converted amino acid 774 from Arg to His and amino acid 864 from Asp to Gly were recreated using site-directed mutagenesis and the mutant ARs expressed in COS 7 and CV1 cells. In both cases, abnormalities of androgen binding and transcriptional activation were consistent with the observed sex phenotype. These results together with others reported previously demonstrate that single amino acid changes within the region encoded by exons D to H of the AR gene can alter androgen binding and are a common cause of complete androgen resistance. The strategy used herein, employing denaturing gradient gel analysis of heteroduplex PCR products, provides a valuable aid to rapid detection of single base mutations in AIS.

Spontaneous clearance of chronic hepatitis C infection is associated with an internal ribosomal entry site IIId stem loop structure variant.

AIM: To investigate if any mutations in hepatitis C virus (HCV) internal ribosome entry site (IRES) can inhibit the translation of viral polyprotein. MATERIALS AND METHODS: A 26-year-old male patient infected with HCV 10 years ago was followed up. After 9 years of chronic infection. The patient had managed to resolve the infection for a period of 9 months, after which the patient experienced a viral recurrence characterized by high viral load and diverse HCV quasispecies. The IRES structures of the viral strains that disappeared were comparable with those that are currently active using structural mutational analysis. RESULTS: A novo mutational position 254 combined with a rarely observed mutation at position 253 in the stem of the IIId subdomain were observed and the new conformation had an octa-apical loop (AGUGUUGG) and a shift in the 3 ` GU from the loop to the stem. CONCLUSIONS: These mutations were found to be highly deleterious, and they affected the direct binding of the IIId loop to the 40S ribosomal subunit with a subsequent inhibition of translation of viral polyprotein and clearance of the virus.

Characterization of mutant androgen receptors causing partial androgen insensitivity syndrome.

The androgen insensitivity syndrome (AIS) is an X-linked disorder caused by mutations of the androgen receptor (AR) gene resulting in a spectrum of sex phenotypes that ranges from complete female (complete AIS) to nearly complete male (partial AIS). Using the polymerase chain reaction and denaturing gradient gel electrophoresis, we have analyzed the AR gene in three 46,XY individuals with partial AIS. In one subject whose androgen insensitivity was manifest at birth by clitoromegaly, posterior labial fusion, and a urogenital sinus, androgen-binding affinity in genital skin fibroblasts was similar to that of the control. In this subject, a mutation was identified in exon C encoding the second zinc finger of the androgen receptor. The mutation converted a leucine residue at position 616 to arginine, causing greatly reduced binding of receptor to an androgen-response element DNA sequence. However, the mutant AR retained a low level of transcriptional activity at physiological androgen concentrations in keeping with the subject's phenotype of partial AIS. In the second subject, who also had an ambiguous external genital phenotype, a single base mutation was identified in exon G, converting arginine at position 840 to histidine. Androgen-binding affinity in genital skin fibroblasts of this subject was 7-fold lower than control, and the mutant receptor had reduced transcriptional activity. In the third subject, who had a female phenotype with normal pubic hair reflecting a low degree of androgen responsiveness, the valine residue at position 889 was replaced by methionine. This mutant receptor had apparent normal androgen-binding affinity but reduced androgen-binding capacity when examined by expression of the recreated mutant AR in COS 7 cells. These results demonstrate the clinical, functional, and molecular heterogeneity in the syndrome of partial androgen insensitivity.

Molecular analysis of androgen resistance syndromes in Egyptian patients.

Androgen resistance syndromes [i.e. 5 alpha-reductase deficiency (5 alpha RD) and androgen receptor (AR) defects] are frequently reported among Egyptian intersex patients. This study examined AR and 5 alpha-reductase 2 (5 alpha R2) gene mutations among a sample of such cases as a first step towards instituting a screening program. Five families with a typical hormonal profile of 5 alpha RD were screened for major deletions of exons 3-5 of the 5 alpha R2 gene, using polymerase chain reaction (PCR) and electrophoresis. Thereafter, screening for point mutations was carried out by single strand conformational polymorphism (SSCP) analysis, followed by nucleotide sequencing. Seven patients with androgen insensitivity syndrome (AIS) were subjected to molecular analysis of AR exons B-H by a similar protocol, except for the use of denaturing gradient gel electrophoresis (DGGE) for screening point mutations. No major deletions were found in either gene. One family had abnormal electrophoretic mobility on SSCP of exon 5 of the 5 alpha R2 gene, resulting from a point mutation (C to T substitution) at codon 246. Another family, showing retarded mobility on DGGE, had a point mutation (G to A substitution) at codon 889 of the AR gene. In conclusion, the study revealed two mutations previously reported in other geographically distinct populations, inferring the possibility of mutational hot spots in the genes.

Assay for hepatitis C virus in peripheral blood mononuclear cells enhances sensitivity of diagnosis and monitoring of HCV-associated hepatitis.

Hepatitis C virus (HCV) is a major etiological factor in chronic hepatitis affecting up to 24% of blood donors in Egypt. Since fluctuating levels of HCV RNA loads, including undetectable values, have been frequently observed in sera of chronic hepatitis patients, this study was designed to assess the sensitivity of PCR amplification for the plus- and minus-RNA strands in peripheral blood mononuclear cells (PBMC) compared to single serum PCR assay. Since the latter test detects viremia in only 79.5% of seropositive cases, the highest sensitivity for HCV diagnosis was achieved (93.20% when applying the combined triple test including PCR amplification of plus-strand in serum, together with plus-strand in PBMC and minus-strand in PBMC. The results of this study indicate that the triple test provides significant information on extrahepatic replication of HCV in a sizable sample of seropositive subjects (429 cases) and improves the assessment of HCV viremia. The cost/effectiveness and speed were upgraded by using capillary/air rapid thermal cycler. The use of the triple assay in HCV diagnosis and post-therapy monitoring is recommended.

Differential display analysis of mRNAs in chronic myelogenous leukaemia.

Analysis of expressed mRNAs with differential display-polymerase chain reaction (DD-PCR) is a powerful tool for the characterization of genes involved in malignant pathways and might identify markers for different phases of chronic myelogenous leukaemia (CML). We examined the presence of BCR-ABL transcripts in 25 CML patients in either the chronic phase or blast crisis. We then analysed the expression of leukocytic RNA transcripts in CML phases. DD-PCR technique was used to examine CML cases with BCR-ABL in comparison with CML cases lacking detectable BCR-ABL transcripts. Our results support the use of differential display not only for characterization of the CML differentially expressed genes but also to locate patterns that can be implemented as valuable fingerprints for each phase of CML.

Comparison between Toxoplasma gondii DNA and specific immunoglobulins during pregnancy.

Early diagnosis of toxoplasmosis in pregnant women can be of great help in early intervention and prevention of congenital disorders that usually lead to fetal death. The purpose of the present study was to evaluate nested PCR amplification of the B1 gene of Toxoplasma gondii before and after treatment and in comparison to serological follow-up during treatment. The efficiency of treatment on the bases of PCR detection of T. gondii DNA was statistically significant, while it was insignificant when anti-toxoplasma specific IgM and IgG antibodies were used. PCR detection of T. gondii DNA when performed on whole blood is a rapid, sensitive and specific diagnostic procedure and is a valuable tool for establishing the diagnosis of T. gondii infection in women before or during pregnancy.

pH-sensitive sodium alginate hydrogels for riboflavin controlled release.

Sodium alginate (SA) grafted with polyglycidyl methacrylate hydrogels (PGMA-g-SA) was prepared as pH sensitive drug delivery matrices for riboflavin (RF). The hydrogel copolymer matrices were compared with calcium alginate (CA) beads for swelling, degradation, entrapment efficiency and in vitro release of RF. The structure, surface morphology of the CA beads and the prepared hydrogels as well as the chemical stability of the encapsulated drug were characterized by FT-IR and SEM, respectively. The results demonstrate that the optimal formulation was achieved with PGMA-g-SA proportion of (0.75 mol/1 g) and loaded RF 0.03 g. It has been observed that the in vitro release study of RF from this formulation was superior to the other ones and was able to maintain the release for ∼3 and 4 days for the simulated intestinal fluid (SIF) and simulated gastric fluid (SGF), respectively. In general, it has been shown that, GMA grafted onto SA enhanced drug entrapment efficiency, decreased swelling and degradation behaviors of the carrier. In addition, it slowed and controlled the release of RF from the PGMA-g-SA hydrogel compared with pure SA beads crosslinked with Ca2+ ions alone, which thereby provides a facile and effective method to improve the drug delivery systems.

Status of diphtheria immunity in the Egyptian population.

In an attempt to evaluate the levels of immunity against diphtheria in the Egyptian population, 709 healthy subjects aged 2 months-105 years and from six regions of Egypt were investigated. An ELISA was used to determine the serum concentration of anti-diphtheria IgG in each subject. Following widely-used criteria for defining levels of protection, 34.1% of the subjects were categorized as susceptible to diphtheria (with < 0.01 IU antitoxin/ml serum), 43.7% were considered to have basic protection (0.01- < 0.1 IU/ml) and only the other 22.1% appeared fully protected (> or = 0.1 IU/ml). The results revealed that most of the subjects aged 2 months-50 years had a basic or fully protective level of IgG against diphtheria, although males were slightly more likely to be unprotected than females (36.2% v. 31.6%) and certain age-groups appeared to be much more likely to be susceptible than others. If outbreaks of diphtheria like those seen in recent years in the former Soviet Union are to be avoided in Egypt, the most susceptible groups of the population need to be given booster immunizations.

Familial Leydig cell hypoplasia as a cause of male pseudohermaphroditism.

A case of familial Leydig cell hypoplasia as a cause of male pseudohermaphroditism is described in two 46,XY female sibs. Biochemical and histologic evidence for such diagnosis is presented.

Dihydrotestosterone regulates plasma sex-hormone-binding globulin in prepubertal males.

Plasma levels of sex-hormone-binding globulin (SHBG) in man are known to be regulated up and down by oestradiol and testosterone, respectively. To determine whether testosterone reduces SHBG level directly or via its conversion into dihydrotestosterone before puberty, the changes of plasma SHBG, testosterone, oestradiol and dihydrotestosterone following human chorionic gonadotrophin stimulation are studied in ten 5 alpha-reductase-deficient and in six normal prepubertal boys. Three main observations provide evidence that dihydrotestosterone plays a major role in SHBG regulation. (1) Basal plasma SHBG in 5 alpha-reductase-deficient is higher than in normal boys (P less than 0.1). (2) Circulating SHBG fails to decrease (P greater than 0.1) after human chorionic gonadotrophin stimulation despite striking elevation of plasma testosterone in 5 alpha-reductase deficiency where negligible dihydrotestosterone response occurs. This is in contrast to normal boys where SHBG is significantly reduced (P less than 0.01) after stimulation. (3). In normal boys the magnitude of plasma dihydrotestosterone response to human chorionic gonadotrophin correlates with that of SHBG (r = 0.72) more than testosterone does versus SHBG (r = 0.36). It is concluded that dihydrotestosterone decreases SHBG concentration in plasma of prepubertal boys. At least part of the observed decrease in SHBG following testosterone administration in earlier reports must have occurred after its conversion to dihydrotestosterone.

Schistosoma hematobium soluble egg antigens induce proliferation of urothelial and endothelial cells.

Bladder carcinoma accounts for 26% of reported human malignancies in Egypt, and has been strongly associated with urinary schistosomiasis. Nevertheless, the immediate role of schistosomal egg proteins in bladder carcinogenesis is unexplored. We investigated the effects of crude soluble egg antigens (SEA) of Schistosoma hematobium on urothelial cell proliferation. The proliferation of bovine endothelial Endo, human urothelial J82 and smooth muscle SMC cell lines was assessed by low-density growth assays. SEA induced proliferation of both J82 and Endo cells in a dose-dependent fashion, but not SMC. Preboiling or proteinase K treatment of SEA abolished its effect. In addition, SEA enhanced urothelial expression of B-cell translocation protein (BTG1) and human proliferating cell nuclear antigen (PCNA) mRNAs. Given the strong correlation between cell proliferation and carcinogenesis, the findings suggest that crude SEA may play some role in schistosomal bladder carcinogenesis.

Reduced effects of L-carnitine on glucose and fatty acid metabolism in myocytes isolated from diabetic rats.

Depressed glucose utilization and over-reliance of muscle tissues on fat represents a major metabolic disturbance in diabetes. This study was designed to investigate the relationship between fatty acid oxidation and glucose utilization in diabetic hearts and to examine the role of L-Carnitine on the utilization of these substrates in diabetes. 14CO2 release from [1-14C]pyruvate (an index of PDH activity), [2-14C]pyruvate and [6-14C]glucose (an index of acetyl-CoA flux through the Krebs cycle), [U-14C]glucose (an index of both PDH and acetyl-CoA flux through the Krebs cycle), and [1-14C]palmitate oxidation were studied in cardiac myocystes isolated from normal and streptozotocin-injected rats. Palmitate oxidation was increased twofold in diabetic myocytes compared to normal cells (5.4 +/- 1.45 vs 2.35 +/- 0.055 nmol/mg protein/30 min, p > 0.05). L-Carnitine (5 mM) significantly increased palmitate oxidation (60-70%) in normal cells but had no effect on diabetic cells. The activity of PDH and acetyl-CoA flux through the Krebs cycle was severely depressed in diabetes (58.14 +/- 20.27 and 8.63 +/- 0.62 in diabetes vs 128.75 +/- 11.47 and 24.84 +/- 7.81 nmol/mg protein/30 min in controls, p > 0.05, respectively). The efflux of acetylcarnitine, a by-product of PDH activity was also much lower in diabetic cells than in normal cells but had no effect in diabetes. L-Carnitine also had no effect on 14CO2 release from [U-14C]glucose but significantly decreased that from [6-14C]glucose, which reflects oxidative metabolism suggesting that L-Carnitine decreases oxidative glucose utilization. Thus, these data suggest that the overreliance on fat in diabetes may be in part secondary to a reduction of carbohydrate-generated acetyl-CoA through the Krebs cycle.

The milder phenotype of the dystrophin gene double deletions.

OBJECTIVES: This study aimed to examine the genotypephenotype correlation in Duchenne muscular dystrophy (MD) patients with double deletion (Ddel) mutations in comparison with those having single deletions (Sdel). MATERIALS AND METHODS: The study included 250 Duchenne/Becker MD male patients from whom the 10 Ddel patients were compared with 20 Sdel subjects of same age and disease durations. The patients were subjected to neurological examination including functional disability grading scale (FDGS), molecular analysis of the dystrophin gene and immunohistochemical studies of some muscle biopsies. RESULTS: The mean FDGS value in the Ddel group was lower than that in Sdel patients. The Ddel patients had partial expression of dystrophin in their skeletal muscles, while Sdel cases showed complete absence of the protein. CONCLUSION: Patients with double deletion mutations within the dystrophin gene have a milder phenotype than patients harboring single deletions at either major or minor hot spots of the gene.

Molecular analysis of integrated human papillomavirus 16 sequences in the cervical cancer cell line SiHa.

Human papillomavirus (HPV) 16 is frequently found integrated into cervical cancer cell genomes and these integrations are thought to play a role in tumorigenesis. To investigate the mechanisms of HPV integration and its effect on transcription and chromosomal sequence organization, we have cloned and analyzed the HPV16 integration from the cervical cancer cell line SiHa. Restriction analyses and Southern blotting indicated that approximately 95% of an HPV16 genome was integrated without gross rearrangement. Sequence analysis of the cellular-viral DNA junctions revealed that integration had occurred within the E2 and E4 ORFs where 251 bp of viral sequence was deleted. One viral terminus occurred within sequences of an Alu repeat and a 4-bp homology was present at the site of recombination. Using unique cellular flanking DNA probes, a 4.8-kb deletion of cellular sequences was detected at the site of viral integration. The chromosomal location of the viral integration and cellular deletion were mapped to chromosome 13 using a rodent X human somatic cell hybrid panel. Northern blot analysis using viral subgenomic and 3' cellular probes revealed transcription from the 3' portion of integrated HPV16 (E6, E7, E1) and flanking cellular sequences. The observation of viral-cell transcripts and chromosomal deletions associated with HPV integration may indicate that such events are part of a multistep mechanism leading to the development of cervical cancer.

Deficient 5 alpha-reductase due to mutant enzyme with reduced affinity to steroid substrate.

Enzyme kinetics of 5 alpha-reductase were compared in cultured genital skin fibroblasts taken from 6 control subjects and from an affected subject with 5 alpha-reductase deficiency in whom the diagnosis was established on hormonal grounds. The Km value for testosterone in the mutant enzyme was extremely high (1,427 vs. 185-417 nmol/l in controls). in the mutant enzyme was extremely high (1,427 vs 185-417 nmol/l in controls). A A mutant but stable enzyme with reduced affinity to steroid substrate is reported.

Comparision between Toxoplasma gondii DNA and specific immunoglobulins during pregnancy

Early diagnosis of toxoplasmosis in pregnant women can be of great help in early intervention and prevention of congenital disorders that usually lead to fetal death. The purpose of the present study was to evaluate nested PCR amplification of the B1 gene of Toxoplasma gondii before and after treatment and in comparison to serological follow-up during treatment. The efficiency of treatment on the bases of PCR detection of T. gondii DNA was statistically significant, while it was insignificant when anti-toxoplasma specific IgM and IgG antibodies were used. PCR detection of T. gondii DNA when performed on whole blood is a rapid, sensitive and specific diagnostic procedure and is a valuable tool for establishing the diagnosis of T. gondii infection in women before or during pregnancy

Differential display analysis of mRNAs in chronic myelogenous leukaemia

Analysis of expressed mRNAs with differential display-polymerase chain reaction [DD-PCR] is a powerful tool for the characterization of genes involved in malignant pathways and might identify markers for different phases of chronic myelogenous leukaemia [CML]. We examined the presence of BCR-ABL transcripts in 25 CML patients in either the chronic phase or blast crisis. We then analysed the expression of leukocytic RNA transcripts in CML phases. DD-PCR technique was used to examine CML cases with BCR-ABL in comparison with CML cases lacking detectable BCR-ABL transcripts. Our results support the use of differential display not only for characterization of the CML differentially expressed genes but also to locate patterns that can be implemented as valuable fingerprints for each phase of CML