Search PubMed⌕ Search

Biomedical subjects

A Menon

Publications and source records attributed to A Menon.

At least 55 records · Page 3Linked to original sources
PubMed1993

A set of STS assays targeting the chromosome 22 physical framework markers.

The widespread use of the sequence-tagged site (STS) as a quick, efficient, and reproducible assay for comparing physical and genetic map information promises to facilitate greatly long-range goals of the mapping of the human genome. We have designed 21 STS assays for loci on human chromosome 22. These assays primarily tag the physical framework markers of the long arm of 22, but additional assays have been designed from known genes and loci in the neurofibromatosis 2 (NF2) region. The availability of these assays will make these loci available to the research community without physical transfer of materials and will serve as start points for further efforts to physically map chromosome 22 with yeast artificial chromosome clones.

Animals↗
PubMed1993

Decline in meningococcal antibody levels in African children 5 years after vaccination and the lack of an effect of booster immunization.

Antibodies to group A meningococcal polysaccharide were measured by hemagglutination (HA) and by ELISA in sera obtained from Gambian children before vaccination and 3 weeks, 2 years, and 5 years after vaccination with a group A + group C meningococcal capsular polysaccharide vaccine. Children were 1-4 years old at the time of vaccination. Most showed a good initial response to vaccination, including those aged 1-2 years. However, antibody titers declined progressively during follow-up, and 5 years after vaccination, antibody titers measured by both HA and ELISA had returned to prevaccination levels. This decline was not influenced significantly by a booster dose of vaccine given 2 years after initial immunization. Administration of malaria chemoprophylaxis reduced the rate at which antibody levels fell after initial immunization. Sustained protection of children against group A meningococcal disease will require the development of vaccines that are immunogenic in infants and that can induce T cell memory.

Antibodies, Bacterial↗
PubMed1993

Effect of mode of incorporation of disintegrants on the characteristics of fluid-bed wet-granulated tablets.

A full factorial experimental design was employed to investigate the effects of mode of disintegrant incorporation and concentration in wet-granulated paracetamol tablets manufactured by top-spray fluid-bed. Disintegrants (croscarmellose sodium, sodium starch glycolate, or crospovidone) were incorporated either intragranularly, extragranularly, or distributed equally between the two phases. The results were analysed by a general quadratic equation and response surfaces generated. On examining the results for dissolution studies the combined mode resulted in significantly faster dissolution rates than did the extragranular mode which, in turn, was superior to the intragranular mode of inclusion. These results were reflected in the disintegration studies where the combined mode exhibited the shortest disintegration times for all the disintegrants. Tablet crushing strength was not affected by the mode of incorporation of concentration of the disintegrants. Main as well as interaction effects between the types, mode of incorporation and percent disintegrant employed were significant (P < 0.05) for disintegration time and percent release at 15 min. Croscarmellose sodium exhibited the shortest while crospovidone displayed significantly (P < 0.05) longer disintegration times. Formulations containing crospovidone did not meet official compendial (USP XXII) requirements of 80% in 30 min. In general, croscarmellose sodium and sodium starch glycolate were found to be less sensitive to the mode of incorporation than crospovidone.

Acetaminophen↗
PubMed1993

Sarcoidosis: a review of cases seen at the University Hospital, Kuala Lumpur.

Fourteen cases of sarcoidosis consisting of 7 male and 7 female patients with a mean age of 42.4 years were seen at the University Hospital from 1972 to 1990. There were 10 Indians, 2 Malays, and 2 Chinese. Twelve patients had thoracic involvement. The other common disease manifestations included weight loss, arthralgia, hepatomegaly, erythema nodosum, peripheral lymphadenopathy, and hypercalcaemia. At initial presentation, the disease was in radiographic stage I, II, and III in 8, 3 and one patient respectively. The Kveim test was positive in 7 out of 9 patients. Eight patients required steroid therapy.

Adult↗
PubMed1992

Complete human NF1 cDNA sequence: two alternatively spliced mRNAs and absence of expression in a neuroblastoma line.

Neurofibromatosis type 1 (NF1) is caused by mutations in a large gene on chromosome 17q11.2. Previously described partial cDNAs for this gene predicted a protein related to yeast IRA1/IRA2 and the mammalian RAS GTPase activator protein GAP. To initiate a detailed study of the role of this gene in NF1, we have characterized a set of overlapping cDNAs that represent its complete coding sequence. Our results show that two differentially expressed human NF1 mRNAs differ by a 63-bp insertion in the GAP-related domain. These mRNAs predict two 2,818- and 2,839-amino acid proteins with calculated molecular masses of approximately 317 and 319 kD. Extensive similarity to IRA proteins is evident in a 1,450-amino-acid central segment, roughly between amino acids 900 and 2,350. However, the remainder of the NF1 protein is not significantly similar to other proteins. Interestingly, the SK-N-SH human neuroblastoma line expresses no detectable NF1 mRNA, indicating that expression of NF1 is not essential for viability of this neural crest-derived tumor cell line.

Alternative Splicing↗
PubMed1992

Evidence for the association of unexplained pulmonary hypertension in children with the major histocompatibility complex.

BACKGROUND: A link between primary pulmonary hypertension (PPH) and autoimmune disorders has been postulated. To investigate this relation, we performed immunofluorescent antinuclear antibody tests (ANA) and serological human leukocyte antigen (HLA)-A, B, C, DR, and DQ typing on two groups of Caucasian children with unexplained pulmonary hypertension (PHT) and their parents. METHODS AND RESULTS: Group 1 consisted of 17 children with PPH including two patients with familial PPH and three patients with trivial congenital pulmonary to systemic communications. Group 2 consisted of 13 children with advanced PHT and anatomically large congenital pulmonary to systemic communications (PHT + shunt). Both groups had comparably severe pulmonary vascular disease documented by cardiac catheterization. The following statistically significant data (p less than 0.05) were obtained when the study groups were compared with those published for normal controls. Although positive ANAs and varying titers of autoantibodies were found in both groups of children and mothers (not fathers), +ANAs were only significant for the maternal groups. The PPH (group 1) children had increased frequencies of HLA-DR3, DRw52, and DQw2 and decreased DR5, whereas the group 2 (PHT + shunt) children (also their parents) had no statistically significant alterations in any of the DR or DQ alleles. The PPH mothers had decreased DQw3, an allele in linkage disequilibrium with DR5. CONCLUSIONS: These immunogenetic data suggest that childhood PPH appears to be associated with the major histocompatibility complex alleles HLA-DR3, DRw52, and DQw2. This newly found correlation of juvenile PPH with these alleles adds this disease to the DR3+ group of autoimmune diseases. Further studies are needed to determine whether there is also an immunological or autoimmune component in some children with PHT + shunt lesions because this group lacked an HLA association.

Adult↗
PubMed1991

Pharmacokinetics and bioavailability of papaverine HCl following intravenous, peroral, rectal, vaginal, topical and buccal administration in beagle dogs.

This in vivo study was designed to obtain bioavailability data and a definite pharmacokinetic profile of papaverine HCl in Beagle dogs following intravenous (IV), peroral (PO), rectal, vaginal, topical, and buccal administration of different papaverine HCl formulations. Blood samples were analyzed by high-performance liquid chromatography. The pharmacokinetic parameters were determined using either a curve fitting program (RESID) or a compartment model independent program (AUC-RPP). The plasma concentration-time profiles show that papaverine HCl pharmacokinetics is best described by an open two-compartment model. The absolute bioavailability of papaverine HCl was determined to be 57.2 per cent, 25.2 per cent, 53.2 per cent, 3.2 per cent and 7.5 per cent, respectively, following P.O., rectal, vaginal, topical and buccal administration.

Administration, Buccal↗
PubMed1991

TP53 gene mutations and 17p deletions in human astrocytomas.

Astrocytomas, including the most malignant form, glioblastoma multiforme, are the most frequent and deadly primary tumors of the human nervous system. Recent molecular genetic analyses of astrocytomas have demonstrated frequent chromosome 17 deletions involving the telomeric region of the short arm (17p12-pter). This region contains a candidate tumor suppressor gene, TP53, which has recently been implicated in the etiology of a broad array of human cancers. To study the possible role of TP53 in astrocytoma development, 24 randomly chosen human astrocytic tumors were examined for genomic TP53 sequence aberrations using primer-directed DNA amplification in conjunction with direct sequencing. Five of the 11 grade III astrocytomas (glioblastoma multiforme), but only one of seven grade II astrocytomas (anaplastic astrocytoma) and none of either the grade I astrocytomas or oligodendrogliomas demonstrated distinct point mutations involving the TP53 gene. These data suggest that TP53 mutations may play a role in astrocytoma development and are predominantly associated with higher grade tumors.

Adult↗
PubMed1991

Biopharmaceutic evaluation of furosemide as a potential candidate for a modified release peroral dosage form.

An attempt was made to evaluate some of the criteria for developing a modified release peroral dosage form for furosemide which has a poor bioavailability when given in the conventional peroral dosage forms. The pathway of absorption for furosemide was studied ex vivo employing the Wilson-Wiseman test. Passive absorption was found to be the predominant mechanism of transport across the ileum of the guinea pig followed by active transport to the extent of about 17%. The in situ procedure to study the extent of absorption of furosemide from the various sites in the lumen of the gastrointestinal tract of the rat indicated the stomach to be the major site of absorption followed by the duodenum. It is hence postulated that due to the site-specificity and mechanism of absorption a peroral modified release dosage form having a longer gastric residence time could possibly increase the bioavailability of furosemide.

Administration, Oral↗
PubMed1991

Utilization of village health workers within a primary health care programme in The Gambia.

The utilization of Village Health Workers (VHWs) was studied in a rural area of The Gambia 3 years after the introduction of a village-based Primary Health Care (PHC) programme. Of 23 children who died from conditions treatable at village level, only five were first seen by the VHW. Fourteen were seen elsewhere in the region by staff more qualified than the first tier workers. The implications of this pattern of utilization on the lack of impact of VHWs on mortality are discussed. Only half of the non-fatal illnesses were attended to by VHWs. Reasons for this included such factors as lack of knowledge of services available, shortages of money, absence of the VHW at critical periods and social or political disputes with VHWs. Attempts must be made to tackle these fundamental problems if VHWs are to be successfully incorporated into the health services.

Cause of Death↗
PubMed1990

A genetic linkage map of chromosome 17.

We have developed a genetic linkage map of 19 markers (including nine genes) on human chromosome 17, providing 13 reference points along virtually the entire length of this chromosome. The map covers an estimated 149 cM in length (sex-averaged), with a total length of 214 cM in females and 95 cM in males. This sex difference appears to be significant along virtually the entire length of the map. This map will be useful both for providing reference points for fine structure genetic and physical mapping and for genetic linkage studies of diseases, including von Recklinghausen neurofibromatosis and Charcot-Marie-Tooth disease.

Chi-Square Distribution↗
PubMed1990

The epidemiology of Haemophilus influenzae meningitis in children under five years of age in The Gambia, West Africa.

Haemophilus influenzae meningitis was studied over a 2-year period in children less than 5 years of age in a population-based, prospective study in The Gambia, West Africa. A total of 77 cases were recorded. The incidence was 60 cases/100,000 children less than 5 years of age and 297 cases/100,000 children less than 1 year of age. The peak prevalence was at the age of 5 months; 83% of the children were less than 1 year old and 45% were less than 6 months old. Only 55% of cases recovered completely. The distance to the nearest hospital was an important predisposing factor for a fatal outcome. Two cases were secondary. Many patients were anemic and underweight. The observations show that H. influenzae meningitis in The Gambia has an incidence as high as that in the USA, but that it has 10-fold more devastating outcome. If the infection is to be prevented by vaccination in The Gambia, immunization will have to be given very early in life.

Age Factors↗
PubMed1990

Compliance with malaria chemoprophylaxis over a five-year period among children in a rural area of The Gambia.

We have reviewed a malaria chemoprophylaxis programme in which Maloprim (pyrimethamine and dapsone) has been administered fortnightly by village health workers (VHWs) to approximately 1500 children each year aged 6-59 months resident in 15 primary health care villages in a rural area of The Gambia over 5 years. Reasonable levels of compliance with chemoprophylaxis have been maintained by many children over this period. this has occurred despite minimal outside supervision and support of the programme. Factors which may have affected the level of compliance in individual villages are identified. Large villages and those where social or political factionalism were evident tended to have low levels of compliance. The attitudes of VHWs and mothers to the programme were determined. Most VHWs cooperated enthusiastically and kept accurate records of compliance, despite receiving no compensation from the villagers for administering chemoprophylaxis. The administration of a drug to prevent illness in children was complementary to the curative service provided by VHWs. The chemoprophylactic was widely acceptable and nearly all mothers stated that the tablets were good for their children's health. However, knowledge of the specific purpose of chemoprophylaxis in the prevention of malaria was limited. Improvements in the programme which may result in higher levels of compliance are discussed.

Antimalarials↗
PubMed1990

Evaluation of a primary health care programme in The Gambia. II. Its impact on mortality and morbidity in young children.

Mortality and morbidity in children under 5 years of age were measured in 41 villages and hamlets in a rural area of The Gambia for a 1-year period before and for a 3-year period after the introduction of a primary health care (PHC) programme into 15 of the larger villages in the area. Both infant mortality and child mortality rates fell during the post-intervention period but declines were similar in PHC and in non-PHC villages suggesting that factors such as an up-grading of the Farafenni dispensary, improvements in transport and the survey itself may have played an important part in bringing about these changes. Measurements of morbidity showed a lower prevalence of diarrhoea, vomiting or severe cough in PHC villages after the introduction of the PHC programme. Introduction of the PHC programme had no significant effect on nutritional status or on vaccine coverage. Significant improvements in the health of children in the Farafenni study area have taken place during the past 5 years but the PHC programme is probably only one of the factors that have brought about these changes.

Child Health Services↗
PubMed1989

Human T cell recognition of polymorphic epitopes from malaria circumsporozoite protein.

Lymphocytes obtained from forty individuals living in a malaria endemic area of West Africa were tested for in vitro proliferative responses to peptides representing variant regions of the immunodominant T cell domain of the circumsporozoite protein (amino acids 326 to 345, referred to as Th2R, and 361 to 380, referred to as Th3R) from three distinct strains of Plasmodium falciparum. A total of 83% of the individuals responded to at least one of the six peptides tested, confirming that these epitopes are immunodominant. A much greater number of individuals than expected by chance (32% of the responders to Th2R and 27% of the responders to Th3R) reacted to all three of the variant peptides for that epitope, indicating interdependency of the T cell responses, suggestive of cross-reactivity. Nevertheless, some subjects' T cells were clearly able to distinguish each variant peptide from the others. Using EBV transformed B cells, lymphocytes from 10 of the individuals were HLA typed. In this small group, HLA DRw13 was associated with a positive response to any of the peptides, whereas there was a negative association between DQw3 and response to any of the peptides. These results, although limited by the small sample size, suggest that recognition of T epitopes may be Ir gene linked. Our findings suggest that it may be possible to broaden the immunogenicity of an anti-sporozoite malaria vaccine.

Adult↗