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Biomedical subjects

R Jain

Publications and source records attributed to R Jain.

At least 253 records · Page 14Linked to original sources
PubMedDate not supplied

A novel technique to assay adducts of DNA induced by anticancer agent cis-diamminedichloroplatinum(II).

The dideoxynucleotides d(pGpG) and d(pApG) and the tetradeoxynucleotide d(CpTpApG) were synthesized in solution phase by a modified phosphotriester technique and reacted with the anticancer agent cis-diamminedichloroplatinum(II) (cisplatin). The major products were isolated by HPLC and characterized by NMR and mass spectrometry as cross-link adducts of cisplatin with the neighboring purine bases. The cross-link adducts of d(pGpG) and d(pApG) were dansylated through a 5'-phosphoramidate linkage with ethylenediammine. The labeling efficiency of the adducts was quantitative as in the case of the normal dinucleotides. The modified tetramer was digested with nuclease P1. The excised adduct was enriched by HPLC and labeled with dansyl chloride. The analysis of the postlabeled adduct by HPCL, using a fluorescence detector, detected a peak with retention time corresponding to that of the dansylated cis-Pt(NH3)2d(pApG). Cochromatography with the authentic marker confirmed the identification. The same overall procedure was used to assay calf thymus DNA exposed to cisplatin. The major adducts were identified as cis-Pt(NH3)2d(pGpG) and cis-Pt(NH3)2d(pApG). The quantitative labeling efficiency of platinum adducts combined with highly sensitive fluorescence detection technique (subfemtomol) suggests that fluorescence postlabeling assay could be a novel approach for real-time analysis of DNA modification induced by platinated drugs in biological system.

Animals↗
PubMedDate not supplied

Quantitative analysis of 3'-azido-3'-deoxythymidine incorporation into DNA in human colon tumor cells.

We have previously reported that 3'-azido-3'-deoxythymidine (AZT) can possess significant antineoplastic activity in vitro and in vivo when combined with agents which inhibit de novo thymidylate synthesis. Under these conditions cytotoxicity is closely associated with the degree to which AZT is incorporated into DNA. We now report a fluorescence postlabeling technique by which AZT incorporation into DNA can be quantitated without employing radiolabeled AZT. Cultured human colon tumor (HCT-8) cells were exposed to various concentrations of AZT alone and in combination with 5-fluorouracil (FUra). Control cells received the same amount of medium. DNA was isolated from harvested cell pellets (2 x 10(7)). Enzymatic digestion of DNA to the mononucleotide level followed by HPLC analysis of the digest showed that the DNA preparation was free of RNA contamination. The DNA digest was conjugated with dansyl chloride in situ via the phosphoramidate derivative with ethylenediamine. HPLC analysis of the postlabeled nucleotides using fluorescence detection detected 105, 245, and 479 fmol of 5'-monophosphate of AZT (AZTMP) per microg of DNA from cells exposed to 20, 50, and 100 microM AZT, respectively. FUra (3 microM) doubled the AZT incorporation per microg of DNA in cells exposed to 50 and 100 microM AZT. These findings generally support our previously reported data which quantitated (3H)AZT incorporation into cellular DNA and are discussed in light of the potential clinical utility of this technique in assessing the relationship between AZT incorporation into DNA and therapeutic action.

Antimetabolites, Antineoplastic↗
PubMedDate not supplied

Radiation-induced formation of 3,4-dihydroxyphenylalanine in tyrosine-containing peptides and proteins as a function of X-irradiation dose.

Radiation-induced formation of 3,4-dihydroxyphenylalanine (DOPA) in Tyr and Tyr-containing peptides and proteins was investigated as a function of X-irradiation dose. Irradiated Tyr (0-30 Gy) and the acid hydrolysates of irradiated peptide and protein (0-240 Gy) were conjugated with dansyl chloride. The dansylated amino acids were analyzed by reversed-phase HPLC using fluorescence detection. Formation of DOPA, determined by integrated peak area, increased with dose. Analysis of the major product from irradiated tripeptide Tyr-Gly-Gly detected Gly and DOPA (2:1). Extension of the model study to irradiated BSA and RNase A showed correlation of DOPA formation with Tyr modification up to 120 Gy. Higher dose induced further transformation of DOPA. The fluorescence signal of dansylated DOPA was linear from 1.5 nmol to 0.5 pmol (correlation coefficient of 0.999, n = 3). The detection limit allows the detection of 1 molecule of DOPA/300 molecules of BSA in 5 micrograms of dansylated hydrolysate. Most standard amino acid analysis techniques are limited to detect normal residues of protein. Protein-bound DOPA has been suggested to have a role in the replenishment of reduced transition metal ion involved free-radical-generating system in vivo. Sensitive analysis of protein-bound DOPA will be useful to study amplification of the radical-damaging event.

Animals↗
PubMedDate not supplied

QSPR analysis of flash points.

A quantitative structure property relationship study of the flash point of a diverse set of 271 compounds provided a general three-parameter QSPR model (R(2) = 0.9020, R(2)(cv) = 0.8985, s = 16.1). Use of the experimental boiling point as a descriptor gives a three-descriptor equation with R(2) = 0.9529. Use of the boiling point predicted by a four-parameter reported relationship gives a three-parameter flash point equation with a R(2) value of 0.9247.

Journal Article↗
PubMedDate not supplied

Development and characterization of transdermal drug delivery systems for diltiazem hydrochloride.

Transdermal drug delivery system of diltiazem hydrochloride was developed to obtain a prolonged controlled drug delivery. Both the matrix diffusion controlled (MDC) and membrane permeation controlled (MPC) systems were developed. The matrix diffusion controlled systems used various combinations of hydrophilic and lipophillic polymers, whereas membrane permeation controlled systems were developed using the natural polymer chitosan. The MDC systems were prepared using the cast film method and the MPC systems by an adhesive sealing technique. Both the systems were characterized for in vitro and in vivo performance. The MDC systems were characterized for physicochemical properties such as tensile strength, moisture content, and water vapor transmission. The in vitro release studies showed that the release from the matrix diffusion controlled transdermal drug delivery systems follows a nonfickian pattern and that from the membrane permeation controlled transdermal drug delivery systems follow zero-order kinetics. The release from the matrix systems increased on increasing the hydrophilic polymer concentration, but the release from the membrane systems decrease on cross-linking of the rate controlling membrane and also on addition of citric acid to the chitosan drug reservoir gel. The in vivo studies of the selected systems showed that both systems are capable of achieving the effective plasma concentration for a prolonged period of time. The MPC system achieved effective plasma concentration a little more slowly than the MDC system, but it exhibited a more steady state plasma level for 24 hr.

Acrylates↗
PubMedDate not supplied

Differentiation of calcification from chronic hemorrhage with corrected gradient echo phase imaging.

PURPOSE: The purpose of the current study was to prospectively evaluate the role of corrected gradient echo phase imaging in differentiation of calcified granuloma from chronic hemorrhage. METHOD: Eighty-five patients with single/multiple calcifications and hemorrhages irrespective of their location were studied with corrected gradient echo phase imaging. In all the cases, CT was used as the gold standard for the presence/absence of calcification. RESULTS: All calcified lesions showed positive phase, whereas chronic hemorrhages showed negative phase in all cases. Five calcified lesions showed no phase shift at TE =15 ms and positive shift at TE = 35 ms. Heterogeneous phase shift was observed in three calcified lesions at TE = 35 ms; all three lesions showed positive phase shift at TE = 15 ms. There was no site-specific problem in differentiation of calcification from chronic hemorrhage including in the basal ganglia. CONCLUSION: We conclude that calcified granuloma can be easily differentiated from chronic hemorrhage with corrected gradient echo phase imaging, which may obviate the need for CT for its confirmation.

Adolescent↗
PubMedDate not supplied

Influence of plate design on cortical bone perfusion and fracture healing in canine segmental tibial fractures.

OBJECTIVE: To investigate whether or not the limited contact design of the low-contact dynamic compression plate (LCDCP) provides advantages over the dynamic compression plate (DCP) in the context of cortical bone blood flow, biomechanical properties, and remodeling of bone in segmental tibial fractures. DESIGN: Randomized trial using canines. SETTING: Animal research laboratory. PARTICIPANTS: Eleven canines. INTERVENTION: Segmental tibial fractures were surgically created in canine tibiae. The tibiae were reduced and stabilized with 316L stainless-steel, 3.5-millimeter, ten-hole plates: LCDCP (n = 5) or DCP (n = 6). MAIN OUTCOME MEASUREMENTS: Laser Doppler flowmetry evaluated cortical bone perfusion in the proximal tibia, segmental piece, and distal tibia (a) before fracture, (b) after fracture, (c) immediately after plating, and (d) at ten weeks. After the dogs were killed at ten weeks, bending stiffness and load to failure of the tibiae were assessed. Tibial cortical bone porosity and new bone formation were measured. RESULTS: Cortical bone blood flow was similar between the LCDCP and DCP groups throughout the study. Bending stiffness and load to failure of the tibiae were similar between the two groups. Whereas cortical bone porosity and new bone formation were higher in all plated tibiae at ten weeks compared with controls, no differences in cortical bone porosity were seen between the LCDCP and DCP groups. There was a trend toward significantly more new bone formation in the LCDCP group. CONCLUSION: The LCDCP is not advantageous in fracture healing or restoration of cortical bone perfusion to devascularized cortex in segmental fractures when plate fixation has been chosen for fracture stabilization. The overall injury following segmental devascularization seems more important to outcome than the type of implant used for fracture fixation up to ten weeks.

Animals↗
PubMedDate not supplied

Malakoplakia of bone. A case report.

BACKGROUND: Malakoplakia is an uncommon but distinctive granulomatous disease, characterized by an accumulation of histiocytes or Von Hansemann cells containing intracytoplasmic, laminated Michaelis-Gutmann bodies. CASE: A 3-year-old male presented with a tender swelling in the left gluteal region that had been present for one month. Smears made from a fine needle aspirate showed large histiocytic cells containing intracytoplasmic, basophilic, laminated, targetoid Michaelis-Gutmann bodies resembling Von Hansemann cells in malakoplakia. Histopathology confirmed the diagnosis of malakoplakia of bone. CONCLUSION: This case, histologically proven to be malakoplakia, demonstrated regression of the lesion following therapy. The characteristic cytologic features and presence of Von Hansemann cells may in themselves be diagnostic and obviate the need for biopsy.

Biopsy, Needle↗
PubMedDate not supplied

Localized tenosynovial giant cell tumor of tendon sheath. A case report.

BACKGROUND: Localized tenosynovial giant cell tumor of tendon sheath (TGCT-L) is a benign, slowly growing lesion with a peak incidence in the third to fifth decade of life. It is thought to arise from the synovium of tendon sheaths, frequently affecting interphalangeal joints of the hands, feet, ankles and knees. Although the histopathologic appearances are well established, only a few reports describe the cytomorphology of this lesion. CASE: A 37-year-old female presented with a slowly growing, nontender mass located near the left ankle joint. The cytologic features of localized tenosynovial giant cell tumor of tendon sheath (TGCT-L) include abundant mononuclear histiocytic cells occurring singly and in three-dimensional tissue fragments, hemosiderin within histiocytes and a few multinucleated giant cells. Subsequently, the histopathologic examination of the surgical specimen was proven to be TGCT-L. CONCLUSION: Fine needle aspiration cytology can be used as a diagnostic tool for early and accurate detection of TGCT-L since the cytologic features combined with clinical details are sufficiently distinctive.

Adult↗
PubMedDate not supplied

The adjustable globe: a technique for adjustable strabismus surgery.

BACKGROUND: Conventional adjustable strabismus surgery involves postoperative repositioning of individual muscles anchored to the sclera via adjustable sutures. Greaves has described anchoring opposing rectus muscles to one another, via sutures passing on either side of the limbus. With the muscles disinserted, the "freed" globe can be adjusted to the desired position within the resulting suture cradle. Friction of the sutures against the sclera holds the muscles in place until healing occurs. METHODS: Using a cul-de-sac approach, we performed 23 horizontal and three vertical adjustable globe procedures, with median follow-up of 7 weeks. Four procedures were performed on nonhuman primates, monitored with iris fluorescein angiography. RESULTS: Esodeviations were well corrected, but exodeviations were often grossly undercorrected. Prolonged postoperative discomfort and photophobia were experienced. Possible evidence for mild anterior segment ischemia was noted. CONCLUSION: Concern about poor results with exodeviations, discomfort, and possible anterior segment ischemia led us to abandon this procedure.

Adolescent↗
PubMedDate not supplied

Idiopathic haemochromatosis with unusual CT findings.

Hemochromatosis is rarely seen in India. We report a case of idiopathic hemochromatosis with increased urinary porphyrins. The computed tomography of the kidneys revealed high attenuating specks at the tip of papillae, the significance of which is discussed. This is also the first case report of the disease occurring in a female patient from India.

Female↗
PubMedDate not supplied

Implantation malignancy after laparoscopic cholecystectomy.

Laparoscopic cholecystectomy may result in spillage of gall bladder contents during dissection or delivery of gall bladder through the umbilical port. We report a 50-year-old man who underwent laparoscopic cholecystectomy for suspected calculous cholecystitis. Histology showed a single focus of adenocarcinoma in the gall bladder. There was spillage of gall bladder contents at the umbilical port during delivery. Six months later, he developed adenocarcinoma at the port site. This was treated by wide excision.

Adenocarcinoma↗