De novo mutations in sporadic deletional Duchenne muscular dystrophy (DMD) cases.

Dinucleotide repeat polymorphism based genetic analysis is a powerful approach to gain insight into rare genetic events like germline mosaicism and de novo mutations. The loss of heterozygosity of polymorphic dinucleotide loci at "deletional hotspot" of dystrophin gene can provide direct evidence of carrier status in female relatives of affected DMD patients with overlapped exonic deletions. We have used 4 STR loci of the central deletional hotspot of the dystrophin gene for genetic analysis in sporadic unrelated DMD families. Twenty-nine mothers of sporadic deletional cases were analysed and their carrier status was determined. Eighteen of them showed heterozygosity in the deleted loci suggesting the occurrence of de novo mutations. In 9 cases, the carrier status was indeterminate while 2 showed germline mosaicism. Our observations reiterated the importance of STR analysis in determining the status of mothers of sporadic deletional DMD cases in order to provide proper genetic counselling.

Carrier detection in non-deletional Duchenne/Becker muscular dystrophy families using polymorphic dinucleotide (CA) repeat loci of dystrophin gene.

BACKGROUND & OBJECTIVES: Carrier detection and prenatal diagnosis is of great importance for families with one or more sons affected with Duchenne/Becker muscular dystrophy (D/BMD). In about 35-40 per cent of these patients, the causative mutation does not involve gross rearrangement in the structure of dystrophin gene. In these non-deletional families, genetic counselling can be provided only by linkage analysis. The aim of the present study was to determine the carrier status of female relatives in north Indian families with non-deletional D/BMD using highly polymorphic intragenic dinucleotide (CA) repeat markers. METHODS: Six short tandem repeats (STRs) spanning 5' (1), central (4) and 3' regions of the dystrophin gene were used to analyse 14 unrelated families comprising 68 individuals with 12 female siblings at risk of being carriers. RESULTS: Five female siblings inherited at risk STR haplotype, six inherited normal haplotype and one had meiotic recombination. The intragenic recombinations were observed in three families at the central region STR loci and in one family between the proximal and central regions of the gene. INTERPRETATION & CONCLUSIONS: Our study suggested that at least 6 STR markers spanning 5', central and 3' regions of the dystrophin gene are essential to ascertain one or more informative loci and to rule out recombinations in non-deletional D/BMD families for carrier analysis.

Point mutation and polymorphism in Duchenne/Becker muscular dystrophy (D/BMD) patients.

Duchenne and Becker muscular dystrophies (D/BMD) are caused by mutations in the dystrophin gene. Two-thirds of patients have large intragenic deletions or duplications and the remaining one-third have point mutations, small deletions or insertions. Point mutations are more difficult to detect due to the enormous size (2.4 Mb) of the gene and its large transcript (14 kb). In the present study, a total of 50 DNA samples from unrelated D/BMD (38 DMD and 12 BMD) patients who did not show intragenic deletions by multiplex PCR, were analyzed for detection of point mutations. Single stranded conformation analysis and heteroduplex analysis observed electrophoretic mobility shifts in one (BMD) and two (DMD and BMD) patients, respectively. The mobility shift and heteroduplexes were observed in exon 17 in all of the three patients. Sequencing of the amplified PCR products revealed a nucleotide change (-37 g to t) in the intronic region in two of the patients while a C2268T substitution in the exonic region in one. Mutation database search for D/BMD mutations showed the nucleotide substitution in the exonic region as a novel change in the human dystrophin gene, which was not reported earlier. It resulted in an amino acid transition from threonine to methionine in the 687th position of the dystrophin protein. This novel substitution has been included in the mutation database of Leiden muscular dystrophy pages (http://www.dmd.nl) in the rare polymorphism/mutation category. The substituted nucleotide segregated with the disease phenotype in the family suggesting that it can be directly used for carrier detection and prenatal diagnosis without identification of disease causing mutation.

Resolution of the long-term performance issues at the Waste Isolation Pilot Plant.

The Waste Isolation Pilot Plant (WIPP) is a geological repository for disposal of U.S. defense transuranic radioactive waste. Built and operated by the U.S. Department of Energy (DOE), it is located in the Permian age salt beds in southeastern New Mexico at a depth of 655 m. Performance assessment for the repository's compliance with the 10,000-year containment standards was completed in 1996 and the U.S. Environmental Protection Agency (EPA) certified in 1998 that the repository meets compliance with the EPA standards 40 CFR 191 and 40 CFR 194. The Environmental Evaluation Group (EEG) review of the DOE's application for certification identified a number of issues. These related to the scenarios, conceptual models, and values of the input parameters used in the calculations. It is expected that these issues will be addressed and resolved during the first 5-year recertification process that began with the first receipt of waste at WIPP on March 26, 1999, and scheduled to be completed in March 2004.

Proportion and pattern of dystrophin gene deletions in north Indian Duchenne and Becker muscular dystrophy patients.

Population-based variations in frequency and distribution of dystrophin gene deletions have been recognized in Duchenne/Becker (DMD/BMD) muscular dystrophy patients. In the present study, DNA samples from 121 unrelated DMD/BMD patients from North India were analyzed for deletional studies with multiplex PCR and Southern hybridization. A total of 88 (73%) patients showed intragenic deletions in the dystrophin gene. The observed proportion of gene deletions is relatively high, particularly compared with that of Asian counterparts. However, the distribution of breakpoints across the gene does not show significant variations.

Genotype-phenotype correlation in Duchenne/Becker muscular dystrophy patients seen at Lucknow.

The molecular basis of two allelic forms of muscular dystrophy, Duchenne (DMD) and Becker (BMD), has been explained by frame shift hypothesis. In order to test this hypothesis, deletional mutations in 59 patients confirmed to have DMD and 11 BMD patients were analysed using multiplex polymerase chain reaction and Southern hybridization with dystrophin cDNA probes. Translational reading frame of the dystrophin gene was derived from 'Border type' analysis of exons flanking the intragenic deletions. The correlation between genotype (reading frame) and phenotype (clinical severity) showed higher number of DMD patients (approximately 20%) deviating from the frame shift hypothesis. The patients who deviated had deletions at the central hot spot region of the dystrophin gene. The presence of these deviations in a large number of DMD patients highlights the difficulties in predicting the clinical progression of the disease based only on DNA profile.

Laparoscopic tubectomy: a new dimension in F.W. Programme.

PIP: The technique of laparoscopic tubectomy has been helpful in increasing the popularity of female sterilization operations. To discover the reasons for the comparative popularity of this method, a study was conducted with the following specific objectives: 1) to find out the health status of those who have undergone the tubectomy operation; 2) to find out about postoperative difficulties and problems faced by the patients; 3) to enumerate the reasons for the comparative popularity of the abdominal and laproscopic tubectomy techniques. Results of interviews with 220 women who had undergone a tubectomy are presented in tables and described. Demographic features so described are age, religion, level of education of wife and husband and number of living children. Respondents' experiences of postoperative physical ailments, period of stay in the hospital, period before normalcy in daily life returned and whether or not they would advise others to undergo tubectomy are likewise explained. Suggestions for improving laproscopic tubectomy operative conditions, for expanding its availability and for further study are made. The authors conclude that laparoscopic tubectomy resulted in much shorter hospital stays, far fewer complications, and quicker return to normal activities than abdominal procedures.^ieng

Studies on the morphology and histology of the digestive tract of Bagarius bagarius (Ham).

1. The alimentary tract of Bagarius bagarius is long in accordance with its omnivorous nature and consists of buccal cavity, pharynx, oesophogus, stomach, intestine, and rectum. 2. The month is terminal and bounded by upper and lower lips, which are provided with many villiform teeth. 3. The buccal cavity and pharynx are dorso-ventrally flattened with smooth lining in the former and folded in the latter. Taste buds and mucous cells are present in these parts which help in selection of food and inlubricating the prey respectively. 4. The oesophagus is small but wide and produced into longitudinal folds. Histologically it is composed of the usual 4 layers viz. serosa, muscularis, submucosa and mucosa. The mucosa is stratified and bears mucous cells. 5. The stomach is large, sac-like and divided into a large cardiac and a small pyloric portion. In the submucosa of the cardiac part, gastric glands are present into the cryps of mucosa. 6. The intestine is distinguished into duodenum, ileum and rectum on the basis of folds. These folds are of honey comb type in duodenum, longitudinal in the ileum, and anatamosing in the rectum to form a honey comb. The muscularis of the duodenum is better developed than that of the ileum and is best formed in the rectum, where the mucosa contains abundant mucous cells. 7. The liver consists of 2 lobes and is formed of polygonal cells. Blood capillaries and hepatic ductules are present in it. The gall bladder lies in between the right lobe of liver and duodenum. It consists of connective tissues lined with columnar cells on inner side and serosa on the outer side. 8. The pancreas is diffused and lies concentrated between the liver, stomach and the coils of intestine. It is composed of polyhedral cells, which are aggregated to form acini. The pancreatic tissue is supplied with the pancreatic ductules and blood capillaries.