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Biomedical subjects

R Desai

Publications and source records attributed to R Desai.

At least 19 recordsLinked to original sources

Xerophthalmia clinics in rural eye camps.

Even though the primary prevention of many eye diseases can be effectively incorporated into the existing pattern of rural eye camps, efforts in this direction are restrained and insubstantial. We describe our technique and experience in the prevention of xerophthalmia by organising a distinct entity called a xerophthalmia clinic in our eye camps. The clinic consists of an Ophthalmologist or an Ophthalmic assistant who will exclusively examine children who come to the eye camp. This is perhaps, the first report on rural xerophthalmia clinics, in ophthalmic literature. Over a seven year period from 1984 to 1990 we have conducted 71 xerophthalmia clinics amongst the ninty eye camps organised. A total of 11,370 children were examined in the xerophthalmia clinic out of which 18.9% were afflicted with the disease. Therapeutic doses of Vitamin A were administered on the spot to the afflicted and prophylactic doses were administered to the rest. Intensive health education efforts are made through clinics to effectuate change in dietry habits towards consumption of locally grown DGLV (Dark Green Leafy Vegetables) like Anthenum, chenopodium and Amaranthus. A bipronged offensive consisting of mega-dosing and health education is, for the present and the foreseeable future, the best strategy to combat xerophthalmia in this desert region. A year by year breakdown of prevalence rates in the present study shows that in years of severe drought the prevalence of xerophthalmia increases three fold over the non-drought or mild drought years, thereby demonstrating that drought is a substantial risk factor in developing countries leading to vitamin A deficiency and xerophthalmia.

Child

DNA sequence analysis and comparison of the variable heavy and light chain regions of two IgM, monoclonal, anti-myelin associated glycoprotein antibodies.

The complete variable heavy and light chain gene sequences of two monoclonal, IgM, anti-myelin associated glycoprotein (MAG) antibodies associated with peripheral neuropathy, are presented. Comparative analysis of the two VH regions has revealed that they are 88% homologous to one another and are both members of the VH3 gene family. They are also highly homologous to a gene which is frequently utilized in the fetal B-cell repertoire. The V kappa light chain gene of one of the antibodies is 99% homologous to a V kappa II gene and the V lambda light chain gene of the other antibody is only 72% homologous to other known V lambda genes. Further analysis of V genes utilized by anti-MAG antibodies should reveal the structural basis for their binding activity.

Amino Acid Sequence

Aqueous kinetics of sisomicin sulphate.

Sisomicin sulphate is a new-generation aminoglycoside with a broad spectrum of antimicrobial activity that includes Pseudomonas aeruginosa. It is superior to gentamicin against indole-negative Proteus and some resistant strains of Pseudomonas. The ocular pharmacokinetics of sisomicin have not been explored. We used the agar diffusion technique of microbial assay to determine the aqueous penetration and bioavailability of a subconjunctivally placed standard dose of 20 mg/0.4 ml of sisomicin sulphate in 20 human volunteers undergoing elective cataract surgery. A peak concentration of 16.4 mg/l was found in the aqueous humour 78 minutes after injection, which is 65 times the minimum inhibitory concentration for Pseudomonas. The antibiotic was bioavailable up to 1203 minutes after injection in a concentration of 0.9 mg/l, which easily covers the minimum inhibitory concentration of Staphylococcus aureus and Pseudomonas. The antibiotic disappears from the aqueous humour at the 1434 minute interval (approximately 24 hours). The elimination half-life (t1/2 of sisomicin was determined to be 5.16 hours (K = 0.134/hour) and the aqueous clearance was 2.87 microliters/min.

Aqueous Humor

Cloning and sequence analysis of the VH and VL regions of an anti-myelin/DNA antibody from a patient with peripheral neuropathy and chronic lymphocytic leukemia.

We have cloned and determined the nucleotide sequence of the Ig VH and VL region genes of an IgM kappa mAb that binds to denatured DNA and myelin from a patient (POP) with chronic lymphocytic leukemia and peripheral neuropathy. Sequence analysis indicates that the V region of the kappa L chain gene (PopVK) has 99% homology to a V kappa IIIa germ-line gene and the V region of the mu H chain gene (PopVH) has 96% homology to the VH26 germ-line gene that is a member of the VH3 gene family. It is likely the V kappa and VH genes arose from these respective germ-line genes via somatic mutation or from closely related genes. V kappa III genes have frequently been used by other IgMk mAb especially those with rheumatoid factor activity, and the VH26 gene with no somatic mutation has been used by several anti-DNA antibodies, suggesting the possibility of preferential association of these or related germ-line genes with autoantibodies. The minor differences between the sequences of POP's VH and V kappa genes and sequences used by other autoantibodies, may be responsible for this antibody's crossreactivity with myelin and, as a result, the autoimmune neuropathy.

Amino Acid Sequence

Molecular cloning of a human immunoglobulin heavy chain variable (VH) region with anti-myelin-associated glycoprotein activity.

A cDNA clone that encodes the heavy chain variable region (VH) of an IgM M-protein with anti-myelin-associated glycoprotein (MAG) activity secreted by chronic lymphocytic leukemia cells (B-C11) from a patient with peripheral neuropathy was cloned and sequenced. The JH region was identical to the germline JH4 sequence except for deletion of a thymidine residue at the site of D-JH recombination, and the D region showed greatest homology to DM2. Sequence analysis of the VH region revealed greatest homology to VH26, a member of the VH3 gene family, but homology was only 83.7% over 326 bases, suggesting that it was derived from as yet an unidentified member of the VH3 gene family.

Amino Acid Sequence

Angiotensin-converting enzyme inhibitors. 9. Novel [[N-(1-carboxy-3-phenylpropyl)amino]acyl]glycine derivatives with diuretic activity.

A series of molecules 1 having sulfonamide diuretic moieties covalently linked to non-sulfhydryl angiotensin-converting enzyme inhibitors (ACEI) were prepared and tested for both activities. IC50 values for ACEI as low as 7 nM were observed. Discernable diuretic activity was seen for several hydrochlorothiazide-based molecules. Effects of the ACEI and diuretic structures on the respective potencies are discussed.

Angiotensin-Converting Enzyme Inhibitors

Assessment of elastin maturation by radioimmunoassay of desmosine in the developing human lung.

Desmosine has been quantitated in the normally grown fetal and early infant lung by radioimmunoassay. Desmosine could first be detected at 22 weeks gestation: the concentration of desmosine expressed per milligram lung DNA increased in approximately linear form up to about 55 weeks postconceptional age. The concentration in peripheral lung was approximately half that in whole lung homogenates. Lungs of infants dying with acute HMD and lungs of growth retarded infants showed no significant differences from the normals, although there was a tendency for higher desmosine concentrations in prematurely born growth retarded infants.

Amino Acids

Fetal lung growth in congenital laryngeal atresia.

Morphometric and biochemical indexes of lung growth were measured in 2 cases of uncomplicated laryngeal atresia at 27 and 30 weeks gestation and in 1 case of cryptophthalmos syndrome with anomalies including laryngeal atresia and renal agenesis. Findings were compared with those in normally formed fetuses and newborn infants. The cases of pure laryngeal atresia showed a marked increase in surface area and lung volume for age, associated with an increase in alveolar number and apparent advance in elastin maturation, but little increase in cell population as measured by lung DNA content. Alveolar walls were thin but there was no increase in disaturated phosphatidylcholine (DSPC) content. Similar features were observed in the case of cryptophthalmos in marked contrast to the lung hypoplasia expected to result from renal agenesis. The results give further support to the importance of lung liquid retention for normal fetal lung growth. Overdistention with lung liquid appears to promote alveolar development by redistribution of cells rather than increase in cell population.

Female

Prolactin secretion in Sheehan's syndrome. Responses to thyrotropin-releasing hormone and metoclopramide.

The prolactin response to thyrotropin-releasing hormone (TRH) and metoclopramide was studied in 16 patients with Sheehan's syndrome and 16 matched controls in the follicular phase. Metoclopramide resulted in a greater prolactin response than TRH did in the controls. However, both stimuli failed to evoke any appreciable prolactin response in the patients with Sheehan's syndrome. Since metoclopramide is generally free of side effects and far cheaper than TRH, we recommend the prolactin response to metoclopramide as the preferred screening test in the diagnosis of Sheehan's syndrome.

Adult

Effect on lung growth of cervical cord section in the rabbit fetus.

Experiments were performed to clarify the mechanism by which cervical cord transection retards lung growth in the fetal rabbit. In 10 sets of fetuses operated on at 24 1/2 days gestation and studied 3--4 days later, cord section at C1--C3 (high section) caused a significantly greater reduction in lung weight and lung DNA than cord section at C5--C8 (low section) as compared with control littermates. Comparison with the lungs of additional control fetuses removed at the time of operation showed that high section had reduced lung growth by 70% and low section had reduced growth by 40% relative to sham-operated controls. The hypoplastic lungs of the high-section group had poorly expanded, thick-walled terminal sacs, while those of the low section group more nearly resembled the controls. Fetal weights and weights of liver, kidneys, thymus and diaphragm did not differ significantly between the groups, but the hearts of the low-section group were unduly large. In a separate 6 sets of fetuses tracheal ligation at the time of high-cord section was found to result in large fluid-filled lungs with a normal DNA content. The results indicate that preservation of an upper motor neurone supply to the phrenic nucleus is of critical importance for fetal lung growth, and confirm the growth-promoting effects of liquid distension of the fetal lungs. We conclude that normal fetal lung growth depends on development and maintenance of a sophisticated form of function involving integration of respiratory movements and lung lipid secretion. This functional control of fetal lung growth has important implications for perinatal medicine.

Animals

Studies on the fate of pulmonary surfactant in the lung.

1. Radioactively labelled pulmonary surfactant was prepared in an isolated perfused lung system provided with [14C]hexadecanoate. 2. After intratracheal administration of pulmonary surfactant radioactively labelled components were rapidly distributed into different lung fractions, including macrophages (free cells), but most of the radioactive label was accumulated by the lung tissue. 3. Alveolar macrophages, maintained in a variety of culture media in the presence and absence of mineral particles, incorporated a low percentage (11%) of radioactively labelled components when incubated with the surfactant, although evolution of labelled CO2 (6% of the original total activity) suggested that some breakdown of the components had taken place. 4. In similar cultures little intracellular accumulation or extracellular release of non-esterified fatty acids was demonstrated, indicating minimal catabolism of the high-molecular-weight lipid components of surfactant (particularly phosphatidylcholine). 5. However, experiments in vitro designed to simulate the lysosomal degradation of endocytosed surfactant indicated that the macrophage had enzymes capable of releasing non-esterified fatty acids, particularly hexadecanoate, from the lipoprotein complex. 6. It is argued that lung cells, other than alveolar macrophages, may also have a role in surfactant turnover.

Animals