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Biomedical subjects

R Sharma

Publications and source records attributed to R Sharma.

At least 667 records · Page 37Linked to original sources
PubMedDate not supplied

Inhibition of the biosynthesis of SRP polypeptides and secretory proteins by aflatoxin B1 can disrupt protein targeting.

Cell culture and western blotting studies revealed that aflatoxin B(1) (AFB(1)) inhibits the biosynthesis of two of the constituent polypeptides of signal recognition particle (SRP) (SRP54 and 72). SRP escorts polyribosomes carrying signal peptides from free form in the cytosol to the bound form on endoplasmic reticulum (ER) membrane during protein targeting. These effects of AFB(1) on SRP biosynthesis may inhibit the formation of functional SRP. Our experiments have further shown that AFB(1) also inhibits the biosynthesis/translocation of a secretory protein, preprolactin, which fails to appear in the lumen of ER consequent to the treatment with this hepatocarcinogen. The results of the experiments presented in this article therefore enable us to infer for the first time that aflatoxin B(1) may inhibit the functioning of SRP as an escort and deplete the ER of polyribosomes for secretory protein synthesis. As these secretory proteins are important components of the plasma membrane, gap junctions and intercellular matrix, their absence from these locations could disturb cell to cell communication leading to tumorigenesis.

Aflatoxin B1↗
PubMedDate not supplied

Fluorescence studies on erythrocyte membrane isolated from Plasmodium berghei infected mice.

The erythrocyte host cell plays a key role in the well defined developmental stages of the malarial parasite growth and propogation in the erythrocyte cycle of malaria. The host cell serves the parasites by supplying metabolites and removing the catabolites produced by the obligatory parasites. It has been observed that the plasma membrane of the infected cells show a substantially higher fluidity due to the depletion of cholesterol content from the host cell. The protein component of the membrane is also modulated due to the insertion of new polypeptides of the parasitic origin, which confers upon it new antigenic properties. We have studied the membrane fraction isolated from mice erythrocytes infected with Plasmodium berghei using fluorescent probes like DPH, ANS and series of fluorenyl fatty acids, which permit depth dependent analysis of membrane. We have observed that there is a marked difference in the fluorescence emission wavelength maximum, the dissociation constant Kd of ANS when bound to normal and infected erythrocytes, though relatively small differences are observed in the fluorescence polarisation values of the two cell types. The fluorenyl fatty acids also show the differences when bound to normal and infected erythrocytes, indicating that either they are in a different environment or they have differing binding properties to the two cell types.

Animals↗
PubMedDate not supplied

Immature gastric teratoma.

Gastric teratoma, a very rare tumor of infancy is essentially benign. Immature (embryonic) elements have been described in only three of the sixty-six cases described previously. This report concerns with one "immature" gastric teratoma seen in infancy.

Biopsy, Needle↗
PubMedDate not supplied

Age during breast feeding and timely suckling.

A cross sectional study of 398 mothers and infants was conducted to assess the age at first breast feeding, and its determinants, in Shimla. We found that the timely first suckling rate was 0.10 in urban group and 0.11 in rural group. The median age at initiation of breast feeding was five hours among urban cases and four hours among rural cases. Most of the infants were breast fed by the age of 24 hours which is a positive sign and is higher than previous studies. Absence of definite trend vs mother's education may be due to other factors. A community-based educational programme to promote early breast feeding is required, along with training on lactation management counselling for health workers. This will help in achieving healthy child development through prevention of childhood malnutrition.

Breast Feeding↗
PubMedDate not supplied

Poisoning in children: Indian scenario.

The retrospective data on childhood poisoning from eight regional hospitals in India has been reviewed. The demographic features and types of poisonings encountered have been compared. The analysis of the data indicated that pediatric poisonings constituted 0.23-3.3% of the total poisoning. The mortality ranged from 0.64-11.6% with highest being from Shimla. Accidental poisoning was common involving 50-90% of children below 5 years of age and males outnumbered the females. Suicidal poisoning was seen after 13 years of age and was due to drugs and household chemicals. One of the hospitals in Delhi recorded a very high incidence (66.6%) of drug poisoning in children. The drugs consumed belonged to phenothiazines, antiepileptics and antipyretics. Iron poisoning was seen in younger children. Kerosene was one of the causes of accidental poisoning at all hospitals except Shimla and rural Maharashtra were probably wood charcoal is widely used. Pesticide poisoning was more prevalent in Punjab and West Bengal whereas plant poisoning was very common in Shimla. Significant number of snake envenomation has been recorded from rural Maharashtra. Other less common accidental poisonings in children included alcohol, corrosives, heavy metals, rodenticides, detergents and disinfectants. Thus various regions in the country showed some variation in types and frequency of childhood poisoning which could be attributed to different geographical and socio-economic background.

Adolescent↗
PubMedDate not supplied

Radionuclide scintigraphy in Caroli's disease.

Congenital cystic dilatation of the intrahepatic bile ducts involving the major intrahepatic radicles was first described by Caroli and hence named as Caroli's disease. We present here a case in which the only symptom was intermittent pain in the abdomen for last one-and-a-half-year and a radionuclide scan done effectively, not only diagnosed the disease but also the associated cholangitis.

Caroli Disease↗
PubMedDate not supplied

Molecular toxicology of peroxisome proliferators.

The rat Reuber hepatoma cell cell line, H4IIEC3, has been used in gene transfection studies to study the molecular mechanisms of induction of the acyl CoA oxidase gene, the first and rate-limiting enzyme of the peroxisomal fatty acid beta-oxidation spiral. cDNAs encoding the peroxisome proliferator activated receptor and the 9-cis retinoic acid receptor were transfected into the cells, either in the presence or absence of their cognate ligands (Wy-14,643 and 9-cis retinoic acid respectively), in addition to the acyl CoA oxides promoter linked to a chloramphenicol acetyltransferase reporter gene construct. The above experimental approach has confirmed that the 9-cis retinoic acid receptor acts cooperatively with the peroxisome receptor in mediating activation of the acyl CoA oxidase gene. In addition, in vivo experiments have demonstrated that treatment of rats with peroxisome proliferators substantially increase the hepatic levels of the peroxisome receptor mRNA itself. Taken collectively, the above data provides a wealth of molecular and mechanistic information on perioxisome proliferation in the rat and is discussed in terms of the safety assessment of peroxisome proliferators in man.

Acyl-CoA Oxidase↗
PubMedDate not supplied

CT diagnosis of Meckel diverticulum in a paracolic internal hernia.

The autopsy incidence of internal hernia has been reported to be between 0.2% and 0.9%, and these hernias are usually diagnosed on imaging due to their complications or at surgery. Meckel diverticulum is the most common congenital anomaly of the gastrointestinal tract, occurring in 1% to 3% of the population according to autopsy studies. The condition also is usually diagnosed at surgery, by barium studies or scintigraphy, or on cross-sectional imaging due to complications. We present an unusual case of a large Meckel diverticulum in a right paracolic hernia diagnosed on multidetector computed tomography. This diagnosis was made after attacks of subacute intestinal obstruction with the aid of multiplanar reconstructions. This case emphasizes the role of multidetector computed tomography and postprocessing techniques such as multiplanar reconstruction in the diagnosis of bowel pathology.

Adult↗
PubMedDate not supplied

Dynamic T1-weighted ferumoxides enhanced MRI for imaging liver hemangiomas: preliminary observations.

The T1-based signal-enhancing effects of ferumoxides was studied in five liver hemangiomas on short echo-time gradient-recalled echo dynamic magnetic resonance imaging to assess the utility of this technique to image perfusion patterns in liver hemangiomas. We observed peripheral nodular enhancement with centripetal fill in all hemangiomas. Our results suggest that this imaging technique, after rapid injection of ferumoxides, can be used for lesion characterization.

Aged↗
PubMedDate not supplied

Regulatory changes in glucocorticoid receptors in the skeletal muscle of immature and mature male rats.

Specific binding of [3H]dexamethasone to cytosol and translocation of bound receptor complexes to purified nuclei were studied in the skeletal muscle of immature (3-week) and mature (26-week) Long-Evans male rats. A marked decrease (57%) in the specific binding sites with no apparent change in dissociation constant (Kd) was observed in the skeletal muscle of mature rats compared to immature. Heat activation (25 degrees C for 45 min) significantly enhances the nuclear binding of steroid-receptor complexes in the skeletal muscle of rats of both the ages at almost similar level. Cross-mixing experiments (i.e. binding of activated cytosol from mature rats to nuclei of immature and vice-versa) gave similar values. Interestingly, Ca2+-activated (0 degree C for 45 min with 20 mM Ca2+) nuclear translocation was significantly higher (27%) in the skeletal muscle of immature rats compared to mature. Our results indicate that glucocorticoid receptor level and some physicochemical properties change with age in the skeletal muscle of rats.

Aging↗
PubMedDate not supplied

Ethnopharmacology of Calotropis procera flowers.

An ethanolic extract of the flowers of Calotropis procera was investigated for anti-inflammatory, antipyretic, analgesic and antimicrobial activities. The plant extract reduced the paw swelling induced by carrageenan by 37%, fever in rats by 40% and showed some weak effect in rats on the writhing induced by acetic acid. The growth of both gram-positive and gram-negative bacteria was significantly inhibited. A dose-dependent effect on prostaglandin release was also observed.

Animals↗
PubMedDate not supplied

The transition from a pharmacophore-guided approach to a receptor-guided approach in the design of potent protein kinase C ligands.

The pharmacophore-guided approach used in the first phase of the design of novel protein kinase C (PKC) ligands was based on the study of the geometry of bioequivalent pharmacophores present in diacylglycerol (DAG) and in the more potent phorbol ester tumor promoters. A number of potent DAG lactones were generated by this approach, in which the glycerol backbone was constrained into various heterocyclic rings to reduce the entropic penalty associated with DAG binding. Based on the information provided by X-ray and NMR structures of the cysteine-rich, C1 phorbol ester/DAG binding domain, the DAG lactones were further modified to optimize their interaction with a group of highly conserved hydrophobic amino acids along the rim of the C1 domain. This receptor-guided approach culminated with the synthesis of a series of "super DAG" molecules that can bind to PKC with low nanomolar affinities. These compounds provide insight into the basis for PKC ligand specificity. Moreover, some of the compounds reviewed herein show potential utility as antitumor agents.

Antineoplastic Agents↗