Search PubMed⌕ Search

Biomedical subjects

S Agarwal

Publications and source records attributed to S Agarwal.

At least 253 records · Page 14Linked to original sources
PubMed1992

High-efficiency gene transfer mediated by adenovirus coupled to DNA-polylysine complexes.

Employment of recombinant viruses as gene transfer vectors is limited by constraints on the size and functional design of the genetic material to be transferred as well as potential safety hazards deriving from obligatory co-transfer of viral genetic elements. As an alternative strategy that capitalizes on the efficient cellular entry mechanisms of viruses, we have derived adenovirus-polylysine-DNA complexes whereby foreign DNA is transferred bound to the exterior of the virion. This linkage was accomplished utilizing an antibody bridge in which a monoclonal antibody was rendered competent to carry DNA by the attachment of a polylysine residue. Attachment of the antibody-polylysine to the virus was by virtue of the antibody's specificity for the virion. The resulting vector system mediates high-efficiency gene transfer to target cells in vitro. In addition, this vector design allows greatly enhanced flexibility in terms of the size and design of heterologous sequences that can be transferred. Since this strategy selectively exploits viral entry functions, which are independent of viral gene expression, the potential exists to derive vectors that avoid the hazards deriving from transfer of parent virus genome.

Adenoviridae↗
PubMed1992

Gene transfer to respiratory epithelial cells via the receptor-mediated endocytosis pathway.

Gene-based therapies for a variety of inherited and acquired pulmonary diseases will require the development of vectors capable of safe and efficient transfer of DNA to the respiratory epithelium. The present study examined the feasibility of delivering DNA to respiratory epithelial cells by the receptor-mediated endocytosis pathway. This strategy employs molecular conjugates consisting of a cognate moiety, in this case human transferrin, covalently linked to a DNA-binding moiety, such as a cationic polyamine. Complexes were formed between transferrin-polylysine conjugates (hTfpL) and plasmid DNA carrying the firefly luciferase reporter gene (pRSVL). The conjugate-DNA complexes were added directly to cells in tissue culture and incubated for 24 h, after which cell lysates were analyzed for luciferase enzyme activity by luminometry. An immortalized human respiratory epithelial cell line (HBE1) treated with the transferrin-polylysine-DNA complexes exhibited luciferase enzyme activity significantly augmented over background levels. This respiratory epithelial cell line exhibited greater susceptibility to gene transfer by the transferrin-polylysine conjugates than did non-respiratory epithelial cell lines known to possess high levels of transferrin receptors. Effective gene transfer was shown to require both the DNA-binding moiety and cognate moiety for the cell surface receptor. Specific internalization of the conjugates by the transferrin pathway was verified by competition for the transferrin receptor. In addition, treatment with agents that either increased transferrin receptor number or decreased lysosomal degradation markedly augmented gene expression mediated by the conjugates. Thus, respiratory epithelial cells possess receptors for transferrin that can be exploited to accomplish gene transfer by the receptor-mediated endocytosis pathway.

Animals↗
PubMed1992

A study of the formation of the neural network in the lungs of Perdicula asiatica, as revealed by the cholinesterase technique.

The investigation was undertaken to investigate the formation and association of neural network and their fibres with nerve cells and ganglia in the parenchyma. The staining of the neural network was done by the cholinesterase technique under the maintained pH 5.2, temperature 40 degrees C and incubation period 30 hrs. The neural network was formed by a good number of tortuous thick nerves and was related either with nerve cells or ganglia. At times, it was formed by a good number of thick nerves and a few thin nerves in the connective tissue space.

Acetylcholinesterase↗
PubMed1992

Immunoreactivity with S100 protein as an indicator of pregnancy.

The usefulness as a pregnancy marker, of immunoreactivity with S100 protein antiserum in endometrial curettings and fallopian tubes during pregnancy was assessed. Twenty six placental tissues of various gestational age, two hydatidiform moles and four fallopian tubes removed for ectopic pregnancy were stained with S100 protein polyclonal antiserum by immunoperoxidase technique. Strong immunostaining was found in glands within the decidua and epithelial cells of fallopian tubes during early pregnancy. However, no S100 protein could be demonstrated in the endometrium in various phases, endometrial carcinomas, decidual glands beyond 12 wk of gestation and normal fallopian tubes. The results indicate a relationship between S100 protein and early pregnancy. Positive immunoreactivity with S100 protein antiserum in the decidual glands and fallopian tube epithelium may help in confirmation of doubtful cases of pregnancy.

Biomarkers↗
PubMed1992

Hydatid bone disease of the pelvis. A report of two cases and review of the literature.

Hydatid disease is caused by a parasitic tapeworm Echinococcus. This parasite in larval stage can thrive in many parts of the body, most frequently in the liver. Hydatid disease in bone is rare, but in areas where hydatid disease is endemic, it must always be considered in the differential diagnosis. Two cases of hydatid bone disease of the pelvis are reported. The treatment of choice is a combination of chemotherapy and surgery.

Aged↗
PubMed1992

Gene therapy: a status report.

Gene therapy is a way to treat disease by transfer of genetic material into the cells of a diseased organism. Generally it is transferred in the form of one or few genes. There is a tremendous potential for application of this technique to the treatment of human hereditary diseases, particularly single gene disorders. Due to ethical and practical reasons, it is currently being used only as somatic cell therapy but it could be achieved by germline also. The major problem in gene therapy is achieving an efficient gene transfer and a persistent gene expression in appropriate somatic cells.

Animals↗
PubMed1991

Adenovirus enhancement of transferrin-polylysine-mediated gene delivery.

Gene transfer may be accomplished by the receptor-mediated endocytosis pathway using transferrin-polylysine conjugates. For some target cells, however, gene transfer by this vector is extremely limited, despite the presence of the appropriate surface receptors, a phenomenon attributed to lysosomal degradation of endosome-internalized conjugate-DNA complexes. To enhance DNA escape from the cell vesicle system and thus augment gene transfer by this route, we have used the capacity of adenoviruses to disrupt endosomes as part of their entry mechanism. Adenoviral infection augmented levels of gene transfer by transferrin-polylysine conjugates in a dose-dependent manner: levels of gene transfer of greater than 2000-fold above baseline were achieved. Use of the adenovirus in this context allowed enhanced levels of gene transfer in a variety of target cells, including cell lines otherwise refractory to gene transfer by transferrin-polylysine conjugates. This augmentation was based on adenoviral-mediated vesicle disruption, a process independent of viral gene expression. Thus, the development of specific mechanisms to effect release from the endosome in combination with gene transfer by the receptor-mediated endocytosis pathway will increase the utility of this delivery system by allowing high levels of gene expression in target cells.

Adenoviridae↗
PubMed1991

Susceptibility of glucose-6-phosphate dehydrogenase deficient red cells to primaquine, primaquine enantiomers, and its two putative metabolites. II. Effect on red blood cell membrane, lipid peroxidation, MC-540 staining, and scanning electron microscopic studies.

The effects of primaquine (PQ), its enantiomers [(+)PQ,(-)PQ] and hydroxy metabolites [5-hydroxyprimaquine (5HPQ) and 6-desmethyl-5-hydroxyprimaquine (6D5HPQ)] on cell membranes of glucose-6-phosphate dehydrogenase (G-6-PD) deficient red cells were studied in vitro. There was no significant effect of PQ on the malonyldialdehyde (MDA) content of normal and heterozygous red cells, but it caused a significant increase in MDA in G-6-PD deficient red cells (P less than 0.05). There was no noticeable difference between the effects of the two enantiomers on this variable (P greater than 0.05). Compared to PQ, the hydroxy metabolites produced a significantly greater increase in MDA in all the groups studied (P less than 0.001). Of the two hydroxy metabolites, 6D5HPQ was more toxic than 5HPQ. Staining with MC540 showed that exposure to PQ, its enantiomers and two putative metabolites produced significant fluorescence, indicating that the drug produces marked alterations in membrane fluidity. Although the fluorescence was seen both in normal and heterozygous cells, the effect was marked in hemizygous deficient red cells (P less than 0.001). Scanning electron microscopic (SEM) studies revealed that PQ enantiomers had a stomatocytic effect on red cells of normal, heterozygous and hemizygous G-6-PD deficient red cells, whereas the putative metabolites had an echinocytic effect. The effects were most pronounced in G-6-PD deficient red cells.

Erythrocyte Membrane↗
PubMed1991

The effect of sanguinarine on human peripheral blood neutrophil viability and functions.

Human polymorphonuclear cell (PMN) viability, morphology, adherence, chemotaxis, oxidative metabolism, degranulation and phagocytosis were evaluated following treatment with sanguinarine (SANG). SANG was noncytotoxic to PMNs at all concentrations tested (0.31-200 microM). SANG entered the PMNs rapidly without altering the membrane fluidity and localized in the nuclear matrix. SANG (1.56-6.21 microM) inhibited chemotaxis, chemokinesis and adhesion in a dose-dependent manner, with a complete inhibition at 6.2 microM concentration. Concentrations of SANG up to 1.56 microM did not affect PMN oxidative burst; however, higher concentrations were found to inhibit basal as well as PMA-induced superoxide anion generation. The effect of SANG was time- and dose-dependent, and could be reversed if the PMNs were exposed to 12.5 microM or lower concentrations of SANG for less than 5 min. Autologous serum increased the tolerance of PMNs to SANG. Exogenous Ca2+ or Mg2+ did not alter the SANG-mediated inhibition of PMN functions. Treatment of PMNs with 3.12 microM or higher concentrations of SANG also resulted in inhibition of PMN degranulation and phagocytosis. The results suggest that SANG-mediated inhibition of PMN functions, without cytolysis or resultant release of inflammatory mediators, may have clinical implications.

Alkaloids↗
PubMed1991

Certain mutations observed in the 5' sequences of the G gamma- and A gamma-globin genes of beta S chromosomes are specific for chromosomes with major haplotypes.

In this paper we describe the distribution of some specific sequence differences in the 5' flanking regions of the A gamma- and G gamma-globin genes from 100 Black adult and 57 newborn SS patients from the southeastern United States, from 76 individuals with AS, S-beta-thal, SC, AC, or A-beta-thal, and from 31 normal individuals. Haplotypes for all adult individuals have been previously determined using various restriction endonucleases. The DNA samples were amplified, dot blotted, and hybridized with 32P-labeled specific oligonucleotide probes. All 134 chromosomes with haplotype 19 were positive for the G----T substitution at position -657 (A gamma), while 132 were also positive for the C----G mutation at -369 (G gamma). The three specific changes for the chromosome with haplotype 20 were found on all 54 chromosomes with this haplotype. The C----T mutation at -158 5' to G gamma was present on all 41 chromosomes with haplotype 3, and on two chromosomes with a related atypical haplotype. Normal and beta-thal chromosomes with each of these substitutions had the same 5' subhaplotype as beta S haplotypes 19 or 20, respectively. The close relationship between the occurrence of specific mutations and the haplotype of beta S chromosomes makes the determination of these haplotypes with specific oligonucleotide probes attractive with respect to time and expense.

Adult↗
PubMed1991

The G----A mutation at position +22 3' to the Cap site of the beta-globin gene as a possible cause for a beta-thalassemia.

We describe the occurrence of a chromosome with a G----A mutation at position +22 relative to the Cap site that was found in five patients with beta-thalassemia. All patients had a common type of beta-thalassemia mutation on the second chromosome, namely the frameshift at codon 8 (-AA), the IVS-I-110 (G----A) and the IVS-II-1 (G----A) mutations. The beta genes of two patients, including the 5' and 3' untranslated regions, were completely sequenced and no other mutations, except a few polymorphic sites, were observed. Dot-blot analyses failed to demonstrate this G----A mutation at +22 in nearly 400 beta-thalassemia chromosomes and 180 normal chromosomes. Heterozygotes have the features of a high Hb A2-beta-thalassemia heterozygosity, although the hematological parameters might be less abnormal than observed in heterozygotes for the more common beta-thalassemia mutations. The possibility has been presented suggesting that this mutation might impair the binding of mRNA to ribosomes. Another mutation in this segment of DNA, i.e. a C----G mutation at position +20, is observed exclusively on a chromosome which also carries the C----G mutation at IVS-II-745. It is postulated that the +20 C----G mutation accentuates the beta-thalassemia condition caused by the IVS-II-745 mutation; the mechanism might be similar to that suggested for the G----A at +22 mutation.

Alleles↗
PubMed1991

Significance of mucin stain in uterine cervical cancers.

Histopathological examination of 140 cases of cervical cancer was supplemented with staining for the presence of mucin. Secretion of mucin was detected in 27 cases. Fourteen cases of large cell non-keratinizing (LCNK) squamous cell carcinoma were reclassified, 12 as squamous cell carcinoma with mucin secretion and two as adeno-squamous carcinoma. One case of undifferentiated carcinoma was labelled as adenocarcinoma on the basis of mucin stain. None of the keratinizing squamous cell carcinomas were positive for mucin. The results indicate that mucin expression should be looked for even in those carcinomas where no obvious gland formation is seen.

Adult↗
PubMed1991

Computer based application software for histopathological reporting system.

For better follow up of patient and the immediate retrieval of records, we have developed a computer based application software for histopathological reporting system (HIPRIS). With its help, among others, we can (i) retrieve the biopsy report of a patient from the accession number of the specimen; (ii) find out the number of cases for a particular period as well as can analyse cases by any relevant referral parameter like department, specialty and disease and (iii) find out the time gap between receiving the specimen and reporting of result. Our experience suggests that this system greatly improves the efficiency of the histopathological laboratory.

Biopsy↗