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Biomedical subjects

M Nada

Publications and source records attributed to M Nada.

At least 19 recordsLinked to original sources
PubMed2002

Correlation between CT scan and automated perimetry in supratentorial tumors.

An attempt was made to correlate various types of visual field defects on automated perimetry with the findings of computed tomography in 44 patients of supratentorial tumors. All the patients above the age of 10 years were subjected to complete neurological examination including investigations like plain X-rays and CT scan, however, MRI and angiography were performed wherever indicated. Ocular examination particularly pertaining to neuro-ophthalmological profile was carried out with special emphasis on automated perimetry on Humphrey field analyser. The results indicated that automated perimetry was capable of reliably detecting and quantitating the visual field defects and thus established the location of the tumor in 72% patients when compared to CT scan. Hence, any patient with neuro-ophthalmic features should be subjected to automated perimetry for early diagnosis and probable location of intracranial space occupying lesion affecting visual pathways.

Adult↗
PubMed1999

Contrast sensitivity function in pseudophakics and aphakics.

PURPOSE: To study the effect of posterior chamber intraocular lenses and aphakic spectacles on contrast sensitivity. METHODS: Contrast sensitivity was evaluated in 20 patients in each group of pseudophakics with post chamber IOL (group I), aphakics with spectacle correction (group II), and age and sex-matched normal subjects (group III) using the Pelli-Robson chart. RESULTS: The mean values of log contrast sensitivity in pseudophakics (1.665+/-0.105) and aphakes with spectacle correction (1.5075+/-0.1) were found to be statistically significantly low (t: 5.186, p < 0.001; t: 11.302, p < 0.001, respectively) as compared to the mean value of normal phakic subjects (1.8075+/-0.0576). Further, mean values of log contrast sensitivity in aphakes with spectacles correction were also found to be statistically significantly low (t: 4.727, p < 0.001) when compared to that in pseudophakes. CONCLUSION: From observations of the present study, it can be concluded that posterior chamber IOL implantation offers an added advantage of higher contrast sensitivity, over and above the well documented advantages of increased field of vision, negligible effect on image size and elimination of prismatic effect and spherical aberration of thick glasses.

Aphakia, Postcataract↗
PubMed1998

Mitochondrial very-long-chain acyl-coenzyme A dehydrogenase deficiency: clinical characteristics and diagnostic considerations in 30 patients.

Very-long-chain acyl-CoA dehydrogenase (VLCAD) is an enzyme catalyzing the dehydrogenation of long-chain fatty acids in the first step of mitochondrial fatty acid oxidation. Using an ETF (electron transfer flavoprotein, the physiological electron acceptor of VLCAD) reduction assay, we identified VLCAD deficiency in cultured skin fibroblasts or liver tissue from 30 patients in 27 families. They clinically presented two phenotypes: a 'severe' presentation characterized by an early onset of symptoms, with hypertrophic cardiomyopathy and a high incidence of death, and a 'mild' form with hypoketotic hypoglycaemia, resembling MCAD (medium-chain acyl-CoA dehydrogenase) deficiency. Cells isolated from patients who develop cardiomyopathy characteristically accumulate longer-chain length acylcarnitines (hexadecanoylcarnitine and tetradecanoylcarnitine) when incubated with palmitate. However, cells from patients with the hypoglycaemic presentation produced relatively shorter-chain-length intermediates (mainly dodecanoylcarnitine). Inhibition of carnitine palmitoyl transferase I, in vitro, eliminated these intermediates with cells from both phenotypes indicating their intramitochondrial origin. Although the explanation for these distinct biochemical findings is not obvious, the correlation with the two phenotypes provides an opportunity for accurate prognosis and early implementation of appropriate treatment. Prenatal diagnosis of this life-threatening disorder was successfully performed in seven pregnancies in six of those families by assay of trophoblasts or amniocytes. In an at risk family, diagnosis of an affected fetus by measurement of VLCAD activity in noncultured chorionic villi allowed termination of the pregnancy before 13 weeks of gestation.

Acyl-CoA Dehydrogenase, Long-Chain↗
PubMed1992

NADPH-dependent beta-oxidation of unsaturated fatty acids with double bonds extending from odd-numbered carbon atoms.

The mitochondrial metabolism of 5-enoyl-CoAs, which are formed during the beta-oxidation of unsaturated fatty acids with double bonds extending from odd-numbered carbon atoms, was studied with mitochondrial extracts and purified enzymes of beta-oxidation. Metabolites were identified spectrophotometrically and by high performance liquid chromatography. 5-cis-Octenoyl-CoA, a putative metabolite of linolenic acid, was efficiently dehydrogenated by medium-chain acyl-CoA dehydrogenase (EC 1.3.99.3) to 2-trans-5-cis-octadienoyl-CoA, which was isomerized to 3,5-octadienoyl-CoA either by mitochondrial delta 3,delta 2-enoyl-CoA isomerase (EC 5.3.3.8) or by peroxisomal trifunctional enzyme. Further isomerization of 3,5-octadienoyl-CoA to 2-trans-4-trans-octadienoyl-CoA in the presence of soluble extracts of either rat liver or rat heart mitochondria was observed and attributed to a delta 3,5,delta 2,4-dienoyl-CoA isomerase. Qualitatively similar results were obtained with 2-trans-5-trans-octadienoyl-CoA formed by dehydrogenation of 5-trans-octenoyl-CoA. 2-trans-4-trans-Octadienoyl-CoA was a substrate for NADPH-dependent 2,4-dienoyl-CoA reductase (EC 1.3.1.34). A soluble extract of rat liver mitochondria catalyzed the isomerization of 2-trans-5-cis-octadienoyl-CoA to 2-trans-4-trans-octadienoyl-CoA, which upon addition of NADPH, NAD+, and CoA was chain-shortened to hexanoyl-CoA, butyryl-CoA, and acetyl-CoA. Thus we conclude that odd-numbered double bonds, like even-numbered double bonds, can be reductively removed during the beta-oxidation of polyunsaturated fatty acids.

Acetyl-CoA C-Acyltransferase↗
PubMed1991

In vitro evaluation of micronized low-substituted hydroxypropylcellulose as an insoluble swellable matrix for sustained-release tablets.

Micronized low-substituted hydroxypropylcellulose (L-HPC) was evaluated in vitro as an insoluble swellable matrix carrier for sustained-release tablets, using procainamide hydrochloride, theophylline and indomethacin. The amount of water-soluble fraction and the degree of aggregation of L-HPC particles in water increased with decreases in the particle size. The mechanisms of formation of non-disintegrating matrix tablets by micronized L-HPC are discussed on the basis of fast hydration and gel formation due to loss of the fibrous structural integrity of the cellulose polymer. Simple power law analysis suggests that the drug release from directly compressed L-HPC matrices is affected not only by polymer swelling but also by the drug solubility and the amount of soluble fraction in the matrices.

Cellulose↗
PubMed1991

The use of micronized cellulose disintegrants as insoluble swellable matrices for sustained-release tablets.

Five cellulose disintegrants--low-substituted hydroxypropylcellulose (L-HPC), microcrystalline cellulose (MCC), carboxymethylcellulose (CMC), cross-linked NaCMC (C.L.NaCMC), and CaCMC-were evaluated as directly compressed matrices for sustained-release (SR) tablets in vitro, using procainamide hydrochloride as a model drug. Coarser particles (14-19 microns) of the jet mill ground disintegrants, as well as intact disintegrants, provided rapidly disintegrating tablets with fast drug release but finer particles (2.5-3.5 microns) provided matrix-type SR tablets. The SR tablets based on non-ionic polymers (L-HPC and MCC) did not disintegrate at any pH; those based on anionic polymers (C.L.NaCMC and CaCMC) did not disintegrate at pH 1.2, but they disintegrated gradually from the exterior in water and in a pH 6.8 medium. We conclude that the particle size and concentration of the cellulose disintegrants are determinant factors in the formulation of SR matrices.

Calcium Phosphates↗
PubMed1990

2,4-Dienoyl-coenzyme A reductase deficiency: a possible new disorder of fatty acid oxidation.

Several inherited disorders of fatty acid beta-oxidation have been described that relate mainly to saturated precursors. This study is the first report of an enzyme defect related only to unsaturated fatty acid oxidation and provides the first in vivo evidence that fat oxidation in humans proceeds by the reductase-dependent pathway. The patient was a black female, presenting in the neonatal period with persistent hypotonia. Biochemical studies revealed hyperlysinemia, hypocarnitinemia, normal organic acid profile, and an unusual acylcarnitine species in both urine and blood. The new metabolite was positively identified by mass spectrometry as 2-trans,4-cis-decadienoylcarnitine, derived from incomplete oxidation of linoleic acid. In spite of dietary therapy, the patient died of respiratory acidosis at four months of age. Samples of liver and muscle from the autopsy were assayed for 2,4-dienoyl-coenzyme A reductase activity. Using the substrate 2-trans,4-cis-decadienoylcoenzyme A, the reductase activity was 40% of the control value in liver and only 17% of that found in normal muscle. It is suggested that unsaturated substrates should be used for in vitro testing to cover the full range of potential beta-oxidation defects and that acylcarnitine species identification be used for in vivo detection of this disorder.

Fatty Acid Desaturases↗
PubMed1975

Cutaneous schistosomiasis.

Cutaneous manifestations of schistosomiasis can be produced by human and nonhuman species. They can occur in the invasive stage or oviposition stage. Manifestations in the invasive stage are non-specific and include: 1. severe itching 2. Generalized anaphylactiod reaction with urticarial or erythema multiforme-like eruption. Manifestations in the stage of oviposition are specific and include: 1. Genital and perigenital granulomata; 2. Extragenital cutaneous schistosomal granulomata occurring in sites away from the portocaval anastomoses. The clinical and the histopathologic picture are described. The possible mechanisms of ectopic localisation of schistosomal granulomata are discussed.

Animals↗