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Biomedical subjects

R Kapoor

Publications and source records attributed to R Kapoor.

At least 55 records · Page 3Linked to original sources
PubMed2001

Regulatory mechanisms controlling expression of the DAN/TIR mannoprotein genes during anaerobic remodeling of the cell wall in Saccharomyces cerevisiae.

The DAN/TIR genes of Saccharomyces cerevisiae encode homologous mannoproteins, some of which are essential for anaerobic growth. Expression of these genes is induced during anaerobiosis and in some cases during cold shock. We show that several heme-responsive mechanisms combine to regulate DAN/TIR gene expression. The first mechanism employs two repression factors, Mox1 and Mox2, and an activation factor, Mox4 (for mannoprotein regulation by oxygen). The genes encoding these proteins were identified by selecting for recessive mutants with altered regulation of a dan1::ura3 fusion. MOX4 is identical to UPC2, encoding a binucleate zinc cluster protein controlling expression of an anaerobic sterol transport system. Mox4/Upc2 is required for expression of all the DAN/TIR genes. It appears to act through a consensus sequence termed the AR1 site, as does Mox2. The noninducible mox4Delta allele was epistatic to the constitutive mox1 and mox2 mutations, suggesting that Mox1 and Mox2 modulate activation by Mox4 in a heme-dependent fashion. Mutations in a putative repression domain in Mox4 caused constitutive expression of the DAN/TIR genes, indicating a role for this domain in heme repression. MOX4 expression is induced both in anaerobic and cold-shocked cells, so heme may also regulate DAN/TIR expression through inhibition of expression of MOX4. Indeed, ectopic expression of MOX4 in aerobic cells resulted in partially constitutive expression of DAN1. Heme also regulates expression of some of the DAN/TIR genes through the Rox7 repressor, which also controls expression of the hypoxic gene ANB1. In addition Rox1, another heme-responsive repressor, and the global repressors Tup1 and Ssn6 are also required for full aerobic repression of these genes.

Alleles↗
PubMed2001

Tc-99m-labeled RBC scintigraphy and splenic hemangioma.

PURPOSE: The aim of this study was to assess the diagnostic value of RBC scintigraphy in the evaluation of possible splenic hemangioma. MATERIALS AND METHODS: RBC scintigraphy was performed on a patient with an incidental finding of a splenic mass on computed tomographic scanning. Early and delayed planar and SPECT images were obtained. RESULTS: Delayed images revealed blood pooling of the splenic mass. This finding is similar to the characteristics seen in RBC scintigraphy for hepatic hemangioma. CONCLUSION: RBC scintigraphy may be useful in the evaluation of possible splenic hemangioma.

Aged↗
PubMed2001

Studies on the mechanism of action of a targeted chemotherapeutic drug in living cancer cells by two photon laser scanning microspectrofluorometry.

In this study, we present a spectroscopic study of the entry pattern of a chemotherapeutic drug (AN-152) and its carrier hormone ([D-Lys(6)]LH-RH) into living cancer cells, with the help of our two-photon probes and a home-built localized microspectrofluorometer coupled with two photon laser scanning microscope (TPLSM). Due to the inherent localization ability of TPLSM, we were able to identify the drug and carrier location in different compartments of the cancer cells in vitro. The apparent doxorubicin-assisted nucleic accumulation of AN-152 suggests a possible nuclear action of the drug on cell proliferation.

Antineoplastic Agents↗
PubMed2001

Electrically active axons degenerate when exposed to nitric oxide.

Axonal degeneration is a major cause of permanent deficit in inflammatory neurological diseases such as multiple sclerosis. Axons undergo degeneration specifically at the site of the inflammatory lesions, suggesting that locally produced inflammatory factors mediate the phenomenon. One such factor is nitric oxide (NO), which we have previously reported can cause reversible conduction block in axons. Here we confirm these observations and extend them to show that axons exhibit the early stages of wallerian degeneration if they are conducting impulses at physiological frequencies while they are exposed to the low micromolar concentrations of NO that are likely to occur at sites of inflammation. Rat dorsal roots were concurrently exposed in vivo to both NO and sustained impulse activity at 1, 50, or 100 Hz. Although our in vivo observations necessarily focused on the more acute responses, morphological examination of exposed roots at the end of the recording period revealed nodal and paranodal changes consistent with acute wallerian degeneration in roots stimulated at 50 or 100 Hz. This interpretation was confirmed in a few experiments that were prolonged to permit more obvious indicators of degeneration to develop. In these experiments the formation of myelin ovoids and frank axonolysis occurred in more than 95% of fibers. Roots stimulated at only 1 Hz appeared normal. We propose that the combination of normal impulse traffic and NO at sites of inflammation may cause axonal degeneration and that electrical activity may therefore be an important factor in causing permanent disability in patients with neuroinflammatory disorders.

Action Potentials↗
PubMed2001

Ureteral reconstruction: small intestine submucosa for the management of strictures and defects of the upper third of the ureter.

PURPOSE: We evaluated the effectiveness of small intestine submucosa in ureteral reconstruction. MATERIALS AND METHODS: We report an experimental study in 6 female pigs weighing between 50 and 60 pounds. The animals were anesthetized, midline laparotomy was performed and two-thirds of the diameter of the upper third of the left ureter were incised parallel to the ureteral axis, leaving intact only a third of the ureteral wall for a segment of 7 cm. A 5Fr double-J*; stent was positioned to secure patency at all times. The created gap was then bridged with an small intestine submucosa patch in a cylindrical format, which was subsequently sutured to the proximal and distal ureteral segment. The right ureter served as our control and simple intubated Davis ureterotomy was performed. RESULTS: All animals survived the whole followup of 7 weeks. Histologically there was evidence of epithelial regeneration along the segments reconstructed with small intestine submucosa, supported by a well vascularized collagen and smooth muscle background. There was no evidence of foreign body reaction to the graft material. In vivo patency was confirmed by retrograde pyelography in the bridged ureters 7 weeks after the initial procedure. All the ureters without an small intestine submucosa bridge had ureteral stenosis without evidence of epithelial regeneration. CONCLUSIONS: The use of small intestine submucosa is a novel, effective material for the scaffolding of ureteral defects and/or strictures of the upper ureteral segment in the pig model.

Animals↗
PubMed2001

Influence of lead in soil on mycorrhizal development and plant growth of Cyamopsis tetragonoloba (Linn.) Taub.

Growth of C. tetragonoloba suffered with increase in concentration of Pb in soil. Plant biomass declined significantly at concentrations above 60 ppm of Pb. Roots showed more pronounced impact as compared to shoots. At highest applied concentration of lead (100 ppm), fresh weight of fruits decreased by 33% and dry weight by 52% as compared to control. No significant impact was noticed on the development of mycorrhiza at lower concentrations (15-45 ppm) of lead contamination. At higher concentrations of Pb (60 and 75 ppm), there was a decrease in VAM colonization. VAM hyphae had irregular size and terminated abruptly in outer cortex of root. Number of VAM fungal spores in rhizosphere also decreased with increase in the edaphic Pb concentration.

Fabaceae↗
PubMed2000

Chronic expansion of the renal pelvis: a new method for reconstruction of upper ureteral defects.

OBJECTIVES: To evaluate whether the dilated renal pelvis can be used as an autologous source for the surgical reconstruction of upper ureteral defects or strictures. METHODS: In 7 female pigs, the renal pelvis was expanded by a percutaneously placed Council balloon catheter. Every other day for 4 weeks, the renal pelvis was progressively dilated with a bolus injection of saline and contrast medium, which allowed expansion of the renal pelvis to 70 to 75 mL. Four to six weeks after the initial intervention, 5 to 7 cm of the proximal ureter was resected in an open operation and replaced with a tubularized spiral flap made from the expanded renal pelvis. Three weeks later, the animals were killed, and the area of manipulation was resected for pathologic evaluation. RESULTS: All animals reached the desired expansion of the renal pelvis, and in all cases, the spiral flap was fashioned and anastomosed to the distal ureteral segment, bridging the initial defect (mean length 7 cm). Two animals died from sepsis, 4 and 6 days after the spiral flap reconstruction. A viable ureteral lumen with a patent anastomosis and a functioning pelvocaliceal unit was observed on intravenous urography in all animals. The main histologic findings were a chronic inflammatory process with concomitant mucinous metaplasia and reactive atypia of the tubules. CONCLUSIONS: The use of a balloon expander in the renal pelvis is a safe and effective technique for producing native tissue for the reconstruction of defects or strictures of the upper ureteral segment.

Anastomosis, Surgical↗
PubMed2000

Stone recurrence after endopyelotomy.

OBJECTIVES: The purpose of this study was to evaluate whether repair of the ureteropelvic junction (UPJ) obstruction reduces the incidence of stones in stone-forming patients with concurrent UPJ obstruction. METHODS: We performed a retrospective study evaluating 90 patients with UPJ obstruction who underwent endopyelotomy and simultaneous stone extraction (group A) and 80 patients without UPJ obstruction who underwent only stone extraction (group B). Group A consisted of 52 men and 38 women with an average age of 54.4 years (range 15 to 82), and group B of 46 men and 34 women with an average age of 53.5 years (range 8 to 94). Metabolic evaluation was available in 47 patients of group A and 42 patients of group B. RESULTS: We achieved a stone-free state in all patients of both groups. Stone recurrence was observed in 7 patients (8%) in group A and in 32 patients (40%) in group B. Nine of 47 patients (19%) in group A showed metabolic abnormalities. In group B we found 30 of 42 patients (71.4%) with metabolic abnormalities. CONCLUSIONS: Our results suggest that correction of the anatomic obstruction facilitates the drainage of the previously entrapped urine, and thus decreases the incidence of recurrent urinary stone formation.

Adolescent↗
PubMed2000

Annulation reactions of allene-derived 1,3-dipole with 3-substituted-chromones: unusual recognition of 4pi-component in 3-(N-Aryliminomethyl)chromones through

All-carbon dipole derived by the interaction of triphenylphosphine with allenic ester is able to locate the polarized 2pi-component in 3-formylchromones through a regioselective [2 + 3] addition to the C2-C3 pi-bond, which is followed by deformylation leading to novel 3a,9a-dihydro-1-ethoxycarbonyl-1-cyclopenteno[5, 4-b]benzopyran-4-ones. On the contrary, the dipole recognizes azadiene in 3-(N-aryliminomethyl)chromones through [4 + 3] annulation and initially formed adducts undergo tandem rearrangements to afford novel N-aryl-2, 3-dihydro-4-ethoxycarbonylchromano[2,3-b]azepine-6-ones in good yield.

Journal Article↗
PubMed2000

Do prostatic stents solve the problem of retention after transurethral microwave thermotherapy?

Temporary nonmetallic stents offer an alternative to an indwelling catheter for the management of voiding problems after heat-based therapies for benign prostatic hyperplasia. Patient comfort is improved, and they are able to void immediately after the procedure. Unlike a catheter, stents function on the principle of active drainage. Thus, a functioning detrusor muscle is imperative for stent success. Single-center clinical trials have reported encouraging results; however, predictable success criteria are yet to be established. Multicenter trial data are awaited.

Equipment Design↗
PubMed2000

Transurethral microwave thermotherapy for the treatment of prostatitis.

The lethal action of microwaves on various microorganisms is well established and has been exploited in various clinical settings. Transurethral microwave thermotherapy (TUMT) has become a recognized modality for the treatment of prostatic diseases. Recently, it has been applied for the treatment of patients with nonbacterial prostatitis unresponsive to traditional therapeutic schemes. We review the current literature and present our recent encouraging experience with the in vitro bactericidal effect of microwaves on bacteria considered possible etiologic agents of prostatitis. Thus, we may consider the application of TUMT in patients with chronic bacterial prostatitis.

Bacterial Infections↗
PubMed2000

Tissue expansion: a promising trend for reconstruction in urology.

To evaluate the role of the tissue expansion concept in reconstructive urology, the contemporary literature was reviewed, together with our own results with tissue expansion. The principle of tissue expansion has been applied in cases of bladder augmentation, ureteral dilation for the generation of indigenous tissue and subsequent ureterocystoplasties, ureteral elongation, and dilation of the renal pelvis, producing native tissue for the reconstruction of defects or strictures of the upper ureter. Even though the exact mechanism of action of mechanical strain in different tissues is not known, tissue expansion is a well-accepted technique that can amplify the armamentarium of reconstructive urologists for the management of defects along the urinary tract.

Humans↗
PubMed2000

Endoprostatic stents for management of benign prostatic hyperplasia.

Endoprostatic stents have been developed for relieving bladder outlet obstruction secondary to benign hyperplasia of the prostate. The stents are designed either for permanent or for temporary placement. The short-term temporary stents of various biostable and biodegradable polymers are needed after minimally invasive therapy of prostate with heat. The temporary stents are a management option, whereas the permanent stents are a treatment option. Permanent stents offer immediate relief and their sustained results for 4-7 years make them ideally suited for medically compromised patients.

Biocompatible Materials↗
PubMed2000

The role of steroid hormones in the regulation of vasopressin and oxytocin release and mRNA expression in hypothalamo-neurohypophysial explants from the rat.

Vasopressin and oxytocin release from the neural lobe, and the vasopressin and oxytocin mRNA contents of the supraoptic and paraventricular nuclei are increased by hypertonicity of the extracellular fluid. The factors regulating these parameters can be conveniently studied in perifused explants of the hypothalamo-neurohypophysial system that include the supraoptic nucleus (but not the paraventricular nucleus) with its axonal projections to the neural lobe. Vasopressin and oxytocin release and the mRNA content of these explants respond appropriately to increases in the osmolality of the perifusate. This requires synaptic input from the region of the organum vasculosum of the lamina terminalis. Glutamate is a likely candidate for transmitting osmotic information from the organum vasculosum of the lamina terminalis to the magnocellular neurones, because agonists for excitatory amino acid receptors stimulate vasopressin and oxytocin release, and because increased vasopressin release and mRNA content induced in hypothalamo-neurohypophysial explants by a ramp increase in osmolality are blocked by antagonists of both NMDA (N-methyl-D-aspartate) and non-NMDA glutamate receptors. Osmotically stimulated vasopressin release is also blocked by testosterone, dihydrotestosterone, oestradiol and corticosterone. Both oestrogen and dihydrotestosterone block NMDA stimulation of vasopressin release, and in preliminary studies oestradiol blocked AMPA stimulation of vasopressin release. Thus, steroid inhibition of osmotically stimulated vasopressin secretion may reflect inhibition of mechanisms mediated by excitatory amino acids. Recent studies have demonstrated numerous mechanisms by which steroid hormones may impact upon neuronal function. Therefore, additional work is warranted to understand these effects of the steroid hormones on vasopressin and oxytocin secretion and to elucidate the potential contribution of these mechanisms to regulation of hormone release in vivo.

Animals↗
PubMed2000

Caliceal diverticular calculi: is there a role for metabolic evaluation?

PURPOSE: We report our experience with the treatment and incidence of metabolic abnormalities in patients presenting with caliceal diverticular stones. MATERIALS AND METHODS: We retrospectively evaluated 49 patients with caliceal diverticular stones (group 1) and 44 with simple renal stones (group 2). Each group successfully underwent percutaneous treatment. Mean stone size was 1.7 and 2.5 cm. in groups 1 and 2, respectively. Metabolic evaluation was available in 25 group 1 and 22 group 2 patients. Mean followup was 73.2 and 70. 8 months, respectively. RESULTS: We achieved a stone-free rate of 95. 9% in group 1 and 100% in group 2. There was no metabolic abnormality in 75% of the group 1 patients, while 12% had type II absorptive hypercalciuria, 8% hyperuricosuric hypercalciuria and 4% hyperoxaluria. There were no metabolic abnormalities in 22.7% of the group 2 patients, while 9%, 18% and 9% had types I to III absorptive hypercalciuria, respectively, 13.6% hyperuricosuric hypercalciuria, 13.6% hyperoxaluria, 4.5% hypocitruria and 9% type II absorptive hypercalciuria associated with hypocitruria. CONCLUSIONS: Our results reveal a low incidence of associated metabolic abnormalities in patients with caliceal diverticular stones. Thus, we believe that metabolic abnormalities do not promote caliceal diverticular calculous formation.

Adolescent↗
PubMed2000

Endoscopic injection sclerotherapy control of intractable hematuria following radiation-induced hemorrhagic cystitis. A novel approach.

OBJECTIVE: To establish the utility of endoscopic sclerotherapy using 1% ethoxysclerol for the control of intractable hematuria following post-irradiation telangiectatic cystitis (PTC). METHODS: Our experience of treating 4 patients (one female and three male) with massive exsanguinating hematuria resulting from PTC, using a combined intralesional and perilesional injection of 1% ethoxysclerol, is presented. Observation on the distribution, grading of telangiectasis and pattern of bleeding are made. RESULTS: A dramatic and lasting cessation of the hematuria in all the 4 patients was achieved during the follow-up period varying from 1 month to 4 years. CONCLUSION: Endoscopic injection sclerotherapy is a simple, highly effective, less invasive new technique in the management of massive and intractable hematuria due to radiation-induced telangiectasia of the urinary bladder.

Adult↗
PubMed2000

[Percutaneous treatment of calculosis in caliceal diverticulosis: 13-year experience].

We report our experience with the composition and management of caliceal diverticular stones for the past 13 years at our institution. Fourty patients with caliceal diverticular stones were treated percutaneously at Long Island Jewish Medical Center. The size of the diverticula ranged from 1 to 4.8 cm, with a mean size of 2.27 cm. The stone size ranged from 0.2 to 4.5 cm in diameter with an average of 1.7 cm. Twenty patients underwent a metabolic evaluation. Follow-up ranged from 8 months to 140 months with a mean of 72.5 months. We achieved a stone free rate of 95%. All 40 patients were free of pain and infection. The chemical composition of stones was identified in 38 patients. Twelve patients were found to have mainly calcium phosphate stones, 16 mainly calcium oxalate stones, 7 mainly uric acid stones and 3 were found with milk of calcium in their diverticulum. Thirty-five patients had complete resolution of their diverticula with normal urograms. The remaining 5 patients had at least 50% diminution of the diverticulum size. No one of the latter patients was found to have stone recurrence. Metabolic evaluation of the 40 patients showed in the 75% of the cases any metabolic abnormality, an absorptive hypercalciuria type II in two patients (10%), hyperuricosuric hypercalciuria in two cases (10%) and hyperoxaluria in one (5%). Percutaneous management of caliceal diverticular stones is a safe and effective modality compared to the existing alternative procedures reported in the literature.

Adolescent↗