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Biomedical subjects

A Seth

Publications and source records attributed to A Seth.

At least 37 records · Page 2Linked to original sources
PubMed2003

Stone fragility: its therapeutic implications in shock wave lithotripsy of upper urinary tract stones.

OBJECTIVE: To analyse the impact of stone composition on stone fragility (fragmentation) and clearance of upper urinary tract stones after shock wave lithotripsy (SWL). MATERIAL AND METHODS: Between 1st July 1998 and 31st July 2001, 300 renal and ureteric units of 290 patients (10 being bilateral) underwent SWL for upper urinary tract calculi. The degree of fragmentation was divided into four types: (I) Excellent, (II) Good, (III) Fair and (IV) No fragmentation. Stone composition was done by X-ray diffraction crystallography. A statistical comparison was made between degree of fragmentation, number of shock waves delivered, voltage setting, number of sessions required and requirements of adjuvant procedures according to the stone composition. RESULTS: Stone analysis revealed that 90% of the patients had calcium oxalate stones. Of these 80% were calcium oxalate monohydrate (COM) and 20% calcium oxalate dehydrate (COD). Struvite, apatite and uric acid stones comprised of 6%, 3% and 1% respectively. Type-I fragmentation was achieved up to 63.96%, 50% and 100% in COD, struvite and uric stones respectively as compared to 44.9% and 44.44% for COM and apatite stones. Type-III fragmentation was seen up to 8.79% and 33.3% respectively in COM and apatite as compared to 5.55% or less in other types of the stones suggesting that COM and apatite stones produce larger fragments. The mean number of shock waves, voltage and number of treatments was significantly higher for COM and apatite stones (p value < 0.005) with a stone free rate of only 65-66% and 65-68% respectively at three months (p value < 0.001). Similarly the number of adjuvant procedures required in COM alone was more, i.e. 31 as compared to 17 procedures in rest of the other kinds of stones (p value < 0.05). CONCLUSION: Stone composition in Indian subcontinent is different from the western world. Fragility of a stone varies with the composition of the stone and affects the therapeutic results.

Adolescent↗
PubMed2002

Discovery of osteoblast-associated genes using cDNA microarrays.

Osteoblast maturation is a complex process and involves distinct genotypic changes that are accompanied by specific phenotypic alterations. To identify new bone-related genes in osteoblasts we utilized the high-density mouse GEM1 microarray gene chip from IncyteGenomics, Inc. (St. Louis, Mo). We examined the expression profiles of over 8700 genes during the proliferation (day 3) and the mineralization (day 34) phases of MC3T3-E1 development. More than 8600 genes provided measurable signals. Of these genes, 252 were found to be differentially expressed on days 3 and 34. A large number of these genes have never been previously recognized in the context of osteoblast development. Approximately, 60% of the genes with expressions that were dominant in proliferating osteoblasts consisted of growth-related genes such as TACC3 and Pr22. The expressions of TIS21/BTG2, and a novel gene EST350, were found to peak during the differentiation phase (day 12), suggesting that they may play important roles in osteoblast differentiation. The majority of the genes with expressions that were dominant during the mineralization phase consisted of signal transduction genes and extracellular matrix (ECM) proteins such as lumican and cystatin-C. It is significant that lumican expression could not be detected on day 3, which indicates that this gene may serve as an important marker of postmitotic osteoblasts. The establishment of the expression profiles of these and other genes with various phases of MC3T3-E1 osteoblast development will allow us to distinguish the molecular events at different phases of osteoblast biology.

Animals↗
PubMed2002

Is incidental appendectomy necessary during radical cystectomy?

OBJECTIVE: To find out the incidence of acute appendicitis leading to acute abdominal pain and necessitating appendectomy in the follow-up of patients after radical cystectomy and urinary diversions. METHODS: A prospective 160 consecutive radical cystectomy patients with urinary diversion in whom appendectomy was not done between January 1991 and June 2001 were reviewed for the incidence of acute appendicitis. Ages ranged between 26 and 73 years. There were 143 males and 17 females. 120 patients had ileal conduit, 20 sigmoid neobladder, 5 continent urinary diversion, and 15 ureterosigmoidostomy as urinary diversion. Each patients was followed up regularly till death or last follow-up. The follow-up ranged between 4 months and 10 years (mean 6 years). RESULTS: Intestinal obstruction (11%) and acute pyelonephritis (16%) were the most common causes of acute abdominal pain. The remaining causes include sigmoid neobladder perforation (0.6%), parastomal hernia (0.6%), urinary retention due to mucus (1.8%) and renal colic (1.8%). In all patients, diagnosis was easily made and they were managed accordingly. None of the patients had acute appendicitis requiring appendectomy on follow-up. CONCLUSION: Incidental appendectomy is not required during radical cystectomy as the risk of subsequent appendicitis is extremely low.

Adult↗
PubMed2001

Simian immunodeficiency virus (SIV)-specific cytotoxic T lymphocytes in gastrointestinal tissues of chronically SIV-infected rhesus monkeys.

Although systemic virus-specific cytotoxic T lymphocyte (CTL) responses are of critical importance in controlling virus replication in individuals infected with human immunodeficiency virus 1 (HIV-1), little is known about this immune response in the gastrointestinal (GI) tract. This study investigated the GI tract CTL response in a nonhuman primate model for HIV-1 infection, simian immunodeficiency virus (SIV)-infected rhesus monkeys. Lymphocytes from duodenal pinch biopsy specimens were obtained from 9 chronically SIVmac-infected rhesus monkeys and GI tract lymphocytes were harvested from the jejunum and ileum of 4 euthanized SIVmac-infected rhesus monkeys. Lymphocytes were also assessed in GI mucosal tissues by in situ staining in histologic specimens. SIVmac Gag-specific CTLs were assessed in the monkeys using the tetramer technology. These GI mucosal tissues of chronically SIVmac-infected rhesus monkeys contained levels of CTLs comparable to those found in the peripheral blood and lymph nodes. The present studies suggest that the CD8(+) CTL response in GI mucosal sites is comparable to that seen systemically in SIVmac-infected rhesus monkeys.

Animals↗
PubMed2001

Stent placement to prevent restenosis after angioplasty in small coronary arteries.

BACKGROUND: Lesions in small-diameter vessels (<3 mm) define a group with distinct clinical and morphological characteristics. There is an inverse relationship between vessel size and angiographic restenosis rate. This study assessed whether stents reduce angiographic restenosis in small coronary arteries compared with standard balloon angioplasty. METHODS AND RESULTS: We randomly assigned 351 symptomatic patients needing dilatation of 1 native coronary vessel between 2.3 and 2.9 mm in size to angioplasty alone (n=182) or stent implantation (n=169). The primary end point was angiographic restenosis at 6 months. Secondary end points included death, myocardial infarction, bypass surgery, and target vessel revascularization in hospital and at 6 months. There were no significant differences between groups in terms of major in-hospital complications. There was a trend toward fewer in-hospital events in the stent group (3% versus 7.1% in angioplasty group, P=0.076). Crossovers to stent occurred in 37 patients (20.3%). Repeat angiography at 6-month follow-up was performed in 85.3% of patients. Angiographic restenosis occurred in 28% of the stent group and 32.9% of the angioplasty group (P=0.36). Target vessel revascularization was required in 17.8% versus 20.3% of patients (P=0.54), respectively. CONCLUSIONS: Stenting and standard coronary angioplasty are associated with equal restenosis rate in small coronary arteries. With a lower in-hospital complication rate, stenting may be a superior strategy in small vessels.

Angioplasty, Balloon, Coronary↗
PubMed2001

Downregulation of the potential suppressor gene IGFBP-rP1 in human breast cancer is associated with inactivation of the retinoblastoma protein, cyclin E overexpression and increased proliferation in estrogen receptor negative tumors.

The complex insulin-like growth factor network of ligands, receptors and binding proteins has been shown to be disturbed in breast cancer. In addition to defects in proteins controlling cell cycle checkpoints, this type of aberrations could affect tumor growth and survival thereby influencing both tumor aggressiveness and potential response to treatments. We have previously identified the T1A12/mac25 protein, which is identical to the IGFBP-rP1, as a differentially expressed gene product in breast cancer cells compared with normal cells. Here we compare the expression of IGFBP-rP1 in 106 tumor samples with known status of cell cycle aberrations and other clinicopathological data. This was done using a tumor tissue section array system that allows for simultaneous immunohistochemical staining of all samples in parallel. Cytoplasmic staining of variable intensity was observed in most tumors, 15% lacked IGFBP-rP1 staining completely, 20% had weak staining, 32% intermediate and 33% showed strong staining. Low IGFBP-rP1 was associated with high cyclin E protein content, retinoblastoma protein (pRb) inactivation, low bcl-2 protein, poorly differentiated tumors and higher stage. There was a significantly impaired prognosis for patients with low IGFBP-rP1 protein tumors. Interestingly, IGFBP-rP1 showed an inverse association with proliferation (Ki-67%) in estrogen receptor negative tumors as well as in cyclin E high tumors suggesting a separate cell cycle regulatory function for IGFBP-rP1 independent of interaction with the estrogen receptor or the pRb pathway.

Aneuploidy↗
PubMed2001

Alterations in T cell phenotype and human immunodeficiency virus type 1-specific cytotoxicity after potent antiretroviral therapy.

Cytotoxic T lymphocytes (CTLs) are an important defense against human immunodeficiency virus (HIV) type 1 but ultimately fail to control infection. To determine whether more efficient sustained immunity is induced by suppressing replication, the evolution of T cell phenotypes and HIV-specific CD8+ lymphocytes was prospectively investigated in 41 patients initiating combination therapy. Suppression of viremia to <200 copies/mL was associated with increases in naive cells (CD45RA+62L+) and declines in activated T cells (CD95+ cell counts and CD38+ HLA-DR+). HIV-specific tetramer-staining CD8+ T cells were detected in 6 of 10 HLA-A*0201-positive persons, which declined in 5 with treatment. CTL precursor frequencies were markedly consistent before and after treatment. Eight (72%) of 11 recognized > or =1 immunodominant epitope, representing either a new or an increased CTL response after treatment. Thus, activated CD8+ T cells, including those recognizing immunodominant epitopes, decline with combination therapy. However, the overall level of antigen-specific cells that are capable of differentiating into effectors remains stable, and the recognition of new epitopes may occur.

Anti-HIV Agents↗
PubMed2001

Deep intubation of 8 Fr guiding catheter to deliver coronary stent graft to seal coronary perforation: a case report.

Coronary perforation is an uncommon complication of angioplasty and is a challenging situation to manage. We describe a case of complex multivessel coronary angioplasty complicated by coronary perforation following balloon rupture that was successfully managed with a coronary stent graft. Delivery of the stent graft to the site of vessel rupture required deep intubation of an 8 Fr guiding catheter over the shaft of an inflated balloon. In addition to the availability of covered stents, it is essential to be familiar with various skills necessary to deploy these stents. Cathet Cardiovasc Intervent 2001;54:59-62.

Angioplasty, Balloon, Coronary↗
PubMed2001

Impact of power index, hydroureteronephrosis, stone size, and composition on the efficacy of in situ boosted ESWL for primary proximal ureteral calculi.

OBJECTIVES: The efficacy, safety, feasibility, and outcome of in situ treatment applied to select proximal ureteral calculi was assessed and analyzed with a view to avoiding auxiliary interventions and providing high clearance rates in the shortest possible time. We studied the impact of several clinically important variables, including power index, degree of hydroureteronephrosis (HDUN), stone size, and composition on the efficacy of sequential in situ boosted extracorporeal shock wave lithotripsy (ESWL) in a select group. The power index requirement for the in situ boosted protocol and the impact of the stone size/composition, degree of HDUN, and clearance rates were also analyzed. METHODS: An in situ (no instrumentation) boosted protocol was applied to 130 primary unimpacted proximal ureteral calculi with no prior intervention. A typical session with the Siemens Lithostar Plus comprised 3000 shock waves, in installments of 500, deployed at a power setting of 1 to 4 kV with a gradual stepwise escalation. Sequential boosted additional sessions of ESWL were administered on days 2, 7, and 14, tailored to the degree of fragmentation, clearance status, and amount of residual stone bulk. Several parameters (shock waves, kilovolts used, fluoroscopy time, number of sessions, stone size, composition, fragmentation, clearance, and HDUN) were recorded and the results analyzed statistically. RESULTS: The results were excellent in 83.8%, with a mean duration to complete clearance of 11.3 days. In situ ESWL failed in 7.69%, and the auxiliary intervention rate was 10.7%. Pre-ESWL HDUN was present in 78.3%, the mean power index was 184.6/session/case, and the average stone burden was 8.9 mm(2). Calcium oxalate monohydrate was the most common stone (56%). Renal colic was the most common side effect observed. The power index, fragmentation at the first session, and stone size were found to be the most favorable significant variables affecting stone clearance. The degree of HDUN, number of sessions, and stone composition did not significantly impact the clearance rates. CONCLUSIONS: In situ boosted ESWL should be the first-line therapeutic modality in select unimpacted primary proximal ureteral stones.

Adolescent↗
PubMed2001

Severely encrusted polyurethane ureteral stents: management and analysis of potential risk factors.

OBJECTIVES: To review the management of heavily encrusted and stuck JJ ureteral stents. We report our experience and review current published reports in managing heavily encrusted and stuck JJ stents, the guidelines for management, and the prevention of such problems. METHODS: We reviewed our stent records from January 1994 to December 2000 and analyzed our stent complications and their final outcome. Fifteen patients had heavily encrusted and stuck stents. Of these, 14 were encountered in patients with a sizable stone burden (400 to 650 mm(2)) and 1 occurred in a patient with malignant ureteral obstruction. Sandwich combinations of multiple extracorporeal shock wave lithotripsy/traction and endourologic procedures were used to render them stone and stent free. The stent was examined and the encrustation was analyzed by x-ray crystallography. RESULTS: Of 15 patients, 13 were available for evaluations; 1 patient was lost to follow-up and 1 patient died. The average stone burden was 625 mm(2). The encrustation was localized to the upper end in eight and to the lower and upper end in three. In 4 cases, the entire stent was encrusted, and the lumen was occluded in 12. All 13 patients with stuck, fragmented, and encrusted stents were rendered stone and stent free; 2 of the 13 had clinically insignificant residual stones (less than 2 mm). Calcium phosphate and monohydrate stones were the most commonly encountered stone encrustations. CONCLUSIONS: Stent encrustation is one of the most serious complications of polyurethane JJ stents. Multimodal endourology should form the cornerstone of therapy for heavily encrusted stuck stents. It is important to maintain an efficient computerized stent log under the direct supervision of a physician. Patients with probable risk factors should be monitored even more frequently to avoid mishaps and morbidity.

Adult↗
PubMed2001

Wasp recruitment to the T cell:APC contact site occurs independently of Cdc42 activation.

Cdc42 and WASP are critical regulators of actin polymerization whose function during T cell signaling is poorly understood. Using a novel reagent that specifically detects Cdc42-GTP in fixed cells, we found that activated Cdc42 localizes to the T cell:APC contact site in an antigen-dependent manner. TCR signaling alone was sufficient to induce localization of Cdc42-GTP, and functional Lck and Zap-70 kinases were required. WASP also localized to the T cell:APC contact site in an antigen-dependent manner. Surprisingly, WASP localization was independent of the Cdc42 binding domain but required the proline-rich domain. Our results indicate that localized WASP activation requires the integration of multiple signals: WASP is recruited via interaction with SH3 domain-containing proteins and is activated by Cdc42-GTP concentrated at the same site.

Antigen-Presenting Cells↗
PubMed2001

Efficacy and outcome of surgical intervention in patients with nephrolithiasis and chronic renal failure.

AIM: To prospectively evaluate the efficacy and outcome of surgical intervention in patients with renal stones and chronic renal insufficiency. METHODS: The study was carried out from January 1999 till January 2001. Only patients with chronic renal failure without medical renal disease were taken up for study. All patients were subjected to an ultrasound assessment of the kidney, ureter and bladder. In case of obstructed and infected systems a preliminary percutaneous nephrostomy was carried out. After correction of dyselectrolytemia, acid base imbalance and dialysis (if indicated) patients were subjected to surgical intervention (open surgery or percutaneous nephrolithotomy). ESWL was offered for stones persisting after surgery. The stone burden, composition, therapeutic procedures required to render patients stone free were assessed. The outcome of stone removal on renal function was also evaluated by serial renal dynamic scans and creatinine clearance estimations. RESULTS: Out of 90 patients operated for staghorn or calyceal calculi, complete follow up data was available in 70. Pyelo-nephrolithotomy and percutaneous nephrolithotomy was carried out in 63 and 7 patients respectively. Out of 15 patients with residual stones ESWL was successfully performed in 9 cases. Mixed, calcium oxalate monohydrate, calcium oxalate dihydrate, and struvite stones were encountered in 48%, 14%, 17% and 21% respectively. The average pre operative serum creatinine was 4.76 (1.9-16) mg%. The maximum duration of follow up was 9 months. By the 9th post operative month the average fall in serum creatinine values was 1.53 mg/dl (32%) and the average functional improvement by renal dynamic scans stood at 20.665%. 41 patients were saved from further dialysis. CONCLUSION: Patients with mild to moderate renal failure showed maximal improvement in renal function forestalling or reducing the need for dialysis/renal replacement therapy.

Adult↗
PubMed2001

Malignant paraganglioma of the urinary bladder. A case report.

Paraganglioma (pheochromocytoma) is probably the most fascinating of all tumors as it can present with a wide range of clinical manifestations. Paraganglioma of the urinary bladder is one of the rare tumors and constitute less than 10% of all bladder tumors. The common presentation of paraganglioma of the urinary bladder is painless haematuria, headache, palpitation and anxiety. Malignancy is uncommon and no histological feature is characteristic of malignancy. Invasion of adjacent organs or metastasis to the lymph nodes is the only criteria to suggest malignancy. In the presence of proven metastasis radical cystectomy with pelvic lymphadenectomy is recommended. In the present case the tumor was arising from anterior wall of the bladder away from the bladder neck and that in a large capacity bladder it was possible to get a wide margin for partial cystectomy along with bilateral pelvic lymphadenectomy without violating the oncological principles. At a follow up of two years there is no evidence of recurrence of tumor.

Adolescent↗
PubMed2001

Giant pseudoaneurysm of posterior division of renal artery: a rare complication of pyelolithotomy.

Giant renal artery pseudoaneurysm after pyelolithotomy is an uncommon but important disorder. A case of giant pseudoaneurysm arising from the posterior division of right renal artery following pyelolithotomy is presented. The patient presented with a flank mass six months after pyelolithotomy. CT-scan as well as selective renal angiography revealed a giant pseudoaneurysm arising from the posterior division of renal artery. Nephrectomy was necessitated as selective embolization was not possible due to its extraordinarily large size.

Adult↗
PubMed2001

Pedunculated prolapsing bladder hematoma (pseudotumor) mimicking an anterior vaginal polyp--a clinical curiosity and rare complication of transurethral resection of bladder tumor.

A young woman who presented with a recurrent bladder tumor was detected on follow up to be harboring a prolapsed bladder tumor at the external urinary meatus mimicking an anterior vaginal polyp. Excision and histopathological examination revealed an organized hematoma (pseudotumor). The literature regarding this clinical curiosity and its differential diagnosis is reviewed and discussed.

Adult↗