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Biomedical subjects

A Seth

Publications and source records attributed to A Seth.

At least 91 records · Page 5Linked to original sources
PubMed1999

The role of retroperitoneoscopy in the management of renal and adrenal pathology.

OBJECTIVES: To describe the technique, findings and results of retroperitoneoscopic ablation of recalcitrant renal, giant adrenal and complex peripelvic cysts, and nephrectomy for nonfunctioning congenital anomalous kidneys. PATIENTS AND METHODS: Nine patients (six men and three women, mean age 56 years, range 44-68, five with renal, two with adrenal and two with peripelvic cysts, diameter 6-14 cm) were treated by retroperitoneoscopic cyst ablation using three 10-mm ports. Six further patients (two male and four female, mean age 24 years, range 13-38) underwent retroperitoneoscopic nephrectomy using three or four ports for anomalous nonfunctioning kidneys; three patients had a pelvic kidney, two a horseshoe kidney and one an iliac kidney. Isthmusectomy was also performed in the patients with horseshoe kidneys. RESULTS: Retroperitoneoscopic cyst ablation was successful in all nine patients; the mean (range) operative duration was 69 (50-85) min in patients with simple renal and adrenal cysts, and 185 (160-210) min in patients with peripelvic cysts. The mean (range) blood loss was 130 (50-200) mL and hospital stay 2.33 (2-4) days. At the last follow-up, 15-39 months after the procedure, all patients were asymptomatic and satisfied with the outcome, with no recurrence of cysts. Retroperitoneoscopic nephrectomy with isthmusectomy (when applicable) was successful in the six patients with anomalous kidneys, with a mean (range) operative duration of 105 (85-120) min; the mean (range) blood loss was 116 (75-150) mL and the analgesic requirement 208 (150-250) mg of diclofenac sodium. The hospital stay was 2-3 days and the delay before return to preoperative activity 7-14 days. CONCLUSIONS: Retroperitoneoscopic cyst ablation is a safe and effective method to treat symptomatic cysts of the upper urinary tract which are refractory to other forms of management. Dissection is difficult in patients with peripelvic cysts. Retroperitoneoscopic nephrectomy for anomalous kidneys is a challenging procedure because of the abnormal location, anomalous vessels and presence of an isthmus. With advances in laparoscopy and increasing experience, open surgery for such conditions is likely to become obsolete.

Adolescent↗
PubMed1999

Cytotoxic T lymphocytes specific for the simian immunodeficiency virus.

A non-human primate model for acquired immunodeficiency syndrome (AIDS), the simian immunodeficiency virus (SIV)-infected rhesus monkey, was used to explore the role of the AIDS virus-specific cytotoxic T-lymphocyte (CTL) response in disease pathogenesis. This CTL response was measured using the major histocompatibility complex (MHC) class I/peptide tetramer technology. Large numbers of tetramer-binding CD8+ T lymphocytes were demonstrable not only in the peripheral blood, but in lymph nodes and even in semen of chronically SIV-infected monkeys. The central role of these effector T lymphocytes in containing SIV spread during primary infection was demonstrated by showing that early SIV clearance during primary infection correlated with the emergence of the tetramer binding CD8+ T lymphocytes and that in vivo depletion of CD8+ lymphocytes eliminated the ability of the infected monkeys to contain SIV replication. These observations suggest that an effective AIDS vaccine should elicit a potent virus-specific CTL response. In fact, a live, recombinant SIV vaccine constructed using the attenuated pox virus vector modified vaccinia Ankara (MVA) elicited a high-frequency CTL response, comparable in magnitude to that elicited by SIV infection itself. This suggests that vaccine modalities such as MVA may prove useful in creating an effective human immunodeficiency virus (HIV) vaccine. These studies also indicate the power of both the SIV/macaque model and MHC class I/peptide tetramers for assessing AIDS vaccine strategies.

AIDS Vaccines↗
PubMed1999

Cutaneous metastases in renal cell carcinoma.

Cutaneous metastasis from renal cell carcinoma is believed to be rare. We present our experience with 10 (3.3%) cases seen in the last 12 years among 306 cases of renal adenocarcinoma treated at our center. There were 9 males and 1 female. Age ranged from 30 to 65 years (average 45 years). 5 patients had skin metastases at the time of presentation (stage IV). In one of them the skin nodule, rather than urologic symptoms, was the presenting complaint. 5 patients presented with skin metastasis during follow-up after nephrectomy. The average time to skin metastasis was 51 months for patients in stage I and 13 months in stage IIIb. The scalp was the most common site of metastasis followed by chest and abdomen. 90% of patients had secondaries in at least one other site, most commonly in lungs (4 cases) and bones (5 cases). 4 patients were treated with interferon-alpha 6 MIU, subcutaneously, three times a week for varying periods from 3 to 4 months but there was no response. In conclusion, cutaneous secondaries from RCC, though uncommon, are not very rare. A few patients may present with a skin mass before detection of the renal tumor. Patients with low-stage disease at presentation may also develop cutaneous secondaries, therefore a prolonged follow-up is required. The commonest site for cutaneous metastasis from RCC is the scalp and face. Most patients had at least one other site of systemic metastasis, hence they were not candidates for curative therapy. Interferon therapy was not helpful. Mean survival after detection of cutaneous metastasis was 7 months.

Carcinoma, Renal Cell↗
PubMed1998

Role of mitochondrial membrane potential in concanavalin A-induced apoptosis in human fibroblasts.

Lectins induce apoptosis in a wide variety of cell types but the mechanisms of apoptotic induction are unknown. We examined the role of mitochondrial membrane potential (Psi m) in concanavalin A-induced apoptosis in human diploid fibroblasts. Cells were treated with Con A for 0.5, 1, 3, 5, and 24 h. Con A induced a time-dependent increase of the proportion of TUNEL+ ve cells over 24 h. Psi m was examined by staining cells with the mitochondria-specific fluorescent cationic dye JC-1. Comparison of JC-1 fluorescence within mitochondria by flow cytometry showed that after 3 h, Con A reduced Psi m in a subpopulation of apoptotic cells with smaller cell volume and with apoptotic nuclear morphology. In contrast, Psi m was unchanged in a separate population of viable cells with normal volume and normal nuclear morphology. Cyclosporin A protected cells against reduction of Psi m and also against nuclear condensation and morphological apoptosis. Measurement of intracellular calcium ion concentration ([Ca2+]i) by ratio fluorimetry of fura 2-loaded cells showed that Con A did not affect [Ca2+]i in viable cells but induced a progressive depletion of [Ca2+]i with generation of calcium oscillations in apoptotic cells. Assessment of Bcl-2 in Con A-treated cells demonstrated an initially strong increase in Bcl-2 protein and mRNA but the appearance of degraded Bcl-2 protein at 3 and 5 h after treatment, indicating an inadequate protective response to the Con A stimulation. Collectively, these data indicate that lectin-induced apoptosis in fibroblasts is associated with breakdown of Psi m, loss of [Ca2+]i homeostasis, and induced Bcl-2 expression.

Apoptosis↗
PubMed1998

The role of Ets-1 in mast cell granulocyte-macrophage colony-stimulating factor expression and activation.

Ets-1 is a transcription factor with restricted expression in lymphocytes, and it has been implicated in the regulation of T cell genes such as TCR alpha, TCR beta, CD4, IL-2, and TNF-alpha. We show in this study that Ets-1 is also expressed in some mast cells constitutively and can be induced in primary mast cells with stimuli that activate mast cells. We also show that Ets-1 plays a role in the regulation of granulocyte-macrophage CSF (GM-CSF), a cytokine expressed by activated mast cells. We have characterized a murine growth factor-independent mast cell line, FMP6-, derived from a factor-dependent cell line, FMP1.6. FMP6- has acquired a distinct connective tissue mast cell-like phenotype, as characterized by the expression of mast cell proteases MMCP-4 and MMCP-6, expression of IL-12, and the down-regulation of IL-4. The parental FMP1.6 cell line displays a mucosal mast cell-like phenotype. FMP6- cells have increased Ets-1 expression and achieve growth-factor independence by the autocrine production of GM-CSF and IL-3. Transient transfection of an Ets-1 expression construct in FMP6- cells results in transactivation of a GM-CSF reporter, while a point mutation in the consensus Ets binding site in the conserved lymphokine element, CLE0, abolishes Ets-1 transactivation. Importantly, antisense Ets-1 demonstrates an ability to repress the activity of the GM-CSF reporter. These data suggest a role for Ets-1 in mast cell growth regulation and activation, and because of the central role of mast cells in inflammatory processes, such as asthma and rheumatoid arthritis, they identify Ets-1 as potentially contributing to the pathophysiology of such diseases.

Animals↗
PubMed1998

Recombinant modified vaccinia virus Ankara-simian immunodeficiency virus gag pol elicits cytotoxic T lymphocytes in rhesus monkeys detected by a major histocompatibility complex class I/peptide tetramer.

The utility of modified vaccinia virus Ankara (MVA) as a vector for eliciting AIDS virus-specific cytotoxic T lymphocytes (CTL) was explored in the simian immunodeficiency virus (SIV)/rhesus monkey model. After two intramuscular immunizations with recombinant MVA-SIVSM gag pol, the monkeys developed a Gag epitope-specific CTL response readily detected in peripheral blood lymphocytes by using a functional killing assay. Moreover, those immunizations also elicited a population of CD8+ T lymphocytes in the peripheral blood that bound a specific major histocompatibility complex class I/peptide tetramer. These Gag epitope-specific CD8+ T lymphocytes also were demonstrated by using both functional and tetramer-binding assays in lymph nodes of the immunized monkeys. These observations suggest that MVA may prove a useful vector for an HIV-1 vaccine. They also suggest that tetramer staining may be a useful technology for monitoring CTL generation in vaccine trials in nonhuman primates and in humans.

AIDS Vaccines↗
PubMed1998

Down-regulation of T1A12/mac25, a novel insulin-like growth factor binding protein related gene, is associated with disease progression in breast carcinomas.

To define genes that are essential to the initiation and progression of breast cancer we utilized subtractive hybridization and differential display cloning techniques and isolated over 950 cDNAs from breast cell-lines derived from matched normal and tumor tissue. Of these, 102 cDNAs were characterized by DNA sequencing and Northern blot analysis. GenBank searches showed that one of these genes, T1A12 is identical to mac25, an insulin-like growth factor-binding protein related gene. Antibodies generated against the C-terminal region of the T1A12/mac25 protein were used to investigate its expression in 60 primary breast tissues. Sections of 12 benign, 16 ductal carcinoma in situ and 32 infiltrating ductal carcinoma specimens were examined. Strong immunoperoxidase staining was observed in luminal epithelial cells of normal lobules and ducts, in apocrine cells of cysts and fibroadenomas. Moderate to weak protein expression was found in hyperplastic and DCIS cells, but no specific staining was detected in invasive carcinoma cells. FISH mapping using a PAC clone localized the T1A12/mac25 gene to 4q12-13. Microsatellite length polymorphism was studied using markers for 4q in paired normal and tumor breast tissues. Thirty-three per cent (10/30) of the samples were found to be polymorphic with D4S189 and D4S231 microsatellite markers and LOH was detected in 50% (5/10) of these informative samples. Our data indicate that T1A12/mac25 expression is abrogated during breast cancer progression concomitant with loss of heterozygosity on chromosome 4q. T1A12/mac25 may therefore have a tumor suppressor-like function and its expression could indicate a disease with a more favorable status, having a better prognosis.

Breast Neoplasms↗
PubMed1998

Breast cancer genome anatomy: correlation of morphological changes in breast carcinomas with expression of the novel gene product Di12.

To determine which genes may be activated or inactivated during breast cancer development, we employed two cloning strategies (subtractive hybridization and differential display) using RNA samples from a human breast tumor and its matching normal breast cell line. Of 950 clones isolated, 102 cDNA inserts were analysed by DNA sequencing and database searching. We found 30 clones that were obviously unidentified, with no significant homology to any listed human gene. We focused upon one of the novel genes, Di12, that is differentially expressed as a 1.35 kb RNA in breast cancer tissues and cell-lines, and in several normal tissues. A full length cDNA of this gene was cloned, and its DNA sequence revealed an open reading frame of 339 amino acids. Antibodies to the ten N-terminal amino acids were developed to investigate the expression of Di12 in breast cancer cell-lines and tumors. The Di12 protein was found in tissue sections of infiltrating ductal carcinomas (IDCs), but not in benign or normal breast specimens. RT-PCR analysis confirmed expression of Di12 in 80% of infiltrating ductal carcinomas (IDCs). As IDC constitutes approximately 70% of breast cancers seen clinically, the level of Di12 expression may be predictive of disease progression.

Amino Acid Sequence↗
PubMed1998

The lon protease from Mycobacterium smegmatis: molecular cloning, sequence analysis, functional expression, and enzymatic characterization.

We have charterized a Mycobacterium smegmatis gene encoding a homolog of the ATP-dependent protease Lon (La). Our identification of a Lon homolog, in conjunction with our previous work, identifies M. smegmatis as the first known example of a eubacterium containing both Lon and a complete 20S proteasome (containing both alpha- and beta-subunits). Despite the significant primary sequence divergence between M. smegmatis Lon (Ms-Lon) and E. coli Lon (Ec-Lon), expression of Ms-Lon was only moderately toxic to E. coli cells. The ability of E. coli cells to tolerate expression of Ms-Lon reveals that Ms-Lon does not recognize and degrade essential E. coli proteins. We conclude that discrimination against nonsubstrate proteins is broadly conserved between Ec-Lon and Ms-Lon. Additional conservation of substrate recognition was demonstrated by the ability of Ms-Lon to degrade efficiently RcsA, a natural substrate of Ec-Lon. Purified Ms-Lon displays chymotrypsin-like specificity in peptidase assays that are stimulated by unfolded protein and supported by nonhydrolyzed nucleotide analogs. Maximal peptidase activity requires ATP or dATP. Replacement of Ms-Lon's catalytic Ser with Ala (S675A), Thr (S675T), or Cys (S675C) reduced to background levels Ms-Lon's in vitro peptidase activity. However, by employing a sensitive in vivo assay, based on the degradation of RcsA, we demonstrated that the S675C variant retained specific protease activity. Finally, variants of Ms-Lon, with substututions at or near S675, reduce the enzyme's basal ATPase activity, suggesting a structural interaction between the peptidase and ATPase active sites of Ms-Lon.

ATP-Dependent Proteases↗
PubMed1998

Management of obliterative posttraumatic posterior urethral strictures after failed initial urethroplasty.

PURPOSE: We evaluate the problems encountered during surgery and assess the results of different endoscopic and open surgical methods following failed urethroplasty for posttraumatic posterior urethral stricture. MATERIALS AND METHODS: Since 1992 we have treated 23 patients in whom urethroplasty for posterior urethral strictures failed. Of these patients, 3 had undergone 2 previous repairs and 6 had additional complicating factors, such as fistula, periurethral cavity and false passage. End-to-end anastomosis was done in 14 patients via a transperineal (7) or transpubic (7) approach. In 1 patient substitution urethroplasty using a radial artery based forearm free flap was performed. In 3 patients a 2-stage urethroplasty was done, 4 underwent core-through optical internal urethrotomy and 1 underwent endoscopic marsupialization of a false passage. RESULTS: At 1 to 5-year followup 3 of the 23 patients had restenoses (13%), including 2 in whom previous treatment failed. The remaining 87% of the patients void well and are continent, and there is no worsening of the preexisting potency status. CONCLUSIONS: Previous failed urethral stricture repair complicates management due to fibrosis, impaired vascularity and limited urethra available for mobilization. Recurrent strictures less than 1.5 cm. can be managed successfully with core-through internal urethrotomy. End-to-end anastomosis is possible in the majority with generous use of inferior pubectomy or the transpubic approach with certain modifications. When residual inflammation or long strictures are present a 2-stage procedure is a safer option. Overall, reoperation can offer a successful outcome for the majority of these complex strictures.

Adult↗
PubMed1998

Detection of squirrel monkey retroviral sequences in interferon samples.

BACKGROUND/AIMS: Interferons have been used therapeutically in viral infections, and as immunomodulants in the treatment of different types of cancers. Interferons have been prepared from human lymphoid cell-lines, such as Namalwa, that contain integrated copies of squirrel monkey retrovirus proviral DNA. Squirrel monkey retrovirus is related to simian type D retroviruses, such as Mason-Pfizer monkey virus. Thus it is important to determine if these retroviral sequences are present in interferon preparations purified from human cell lines. METHODS: DNA samples were prepared from 75 commercial interferon preparations and analyzed for squirrel monkey retrovirus sequences by polymerase chain reaction and DNA sequencing. Since single polymerase chain reaction is not as sensitive, a nested polymerase chain reaction strategy was devised in order to detect squirrel monkey retrovirus-pol sequences. Amplification of beta-actin (human) sequences was used to confirm that samples contained human genomic DNA. To determine the authenticity of squirrel monkey retrovirus sequences, we analyzed amplified products by Southern blot hybridization and direct DNA sequencing. RESULTS/CONCLUSIONS: Thirty-nine samples were positive for squirrel monkey retrovirus-pol sequences by nested polymerase chain reaction. It is noteworthy that 29 samples were either weakly or very weakly positive by single polymerase chain reaction, thus stressing the importance of our sensitive polymerase chain reaction assay. However, it remains to be determined whether the residual DNA sequences detected by our sensitive nested polymerase chain reaction assay have biological consequences.

Animals↗
PubMed1998

Utility of three-dimensional echocardiography during balloon mitral valvuloplasty.

OBJECTIVES: We investigated the role of three-dimensional echocardiography in assessing mitral valve anatomy in greater detail in patients immediately before and after balloon mitral valvuloplasty (BMV). BACKGROUND: Three-dimensional echocardiography is a recently developed, evolving imaging technique that allows visualization of intracardiac structures from any perspective. METHODS: We studied 19 patients undergoing BMV using transesophageal echocardiography (TEE) (Chicago, Illinois) to image the mitral valve. The TEE was interfaced to a TomTec three-dimensional workstation that allows electrocardiographic and respiratory cycle gated image acquisition. The acquired images are digitized, and after postprocessing a three-dimensional image is reconstructed. The mitral valve was viewed "en-face" as if looking up from the left ventricle. RESULTS: The mean mitral valve area (by pressure half-time from the Doppler of the two-dimensional echocardiogram) increased after BMV from 0.86+/-0.06 cm2 to 2.07+/-0.10 cm2, p < 0.0001. This was similar to the mitral valve areas obtained by planimetry from the three-dimensional images. The three-dimensional reconstructions showed a complete commissural split in 10 patients and partial splitting in 9 patients. In three of the eight patients who had an increase in the amount of mitral regurgitation secondary to BMV, the three-dimensional reconstructions were able to detect tears within the valve leaflet. One leaflet tear actually extended up to the mitral valve annulus and was associated with the only case of severe mitral regurgitation. CONCLUSIONS: The three-dimensional echocardiographic reconstruction enabled visualization of the mitral valve so that commissural splitting and leaflet tears not seen on the two-dimensional echocardiogram became visible.

Adolescent↗
PubMed1998

Mammary coronary artery anastomosis without cardiopulmonary bypass through minithoracotomy: one year clinical experience.

OBJECTIVE: The recent concept of minimally invasive coronary artery surgery in selected patients has dramatically affected surgical management of coronary artery disease. We explored the possibility of coronary artery bypass grafting of anterior coronary arteries with in situ internal mammary artery through a limited anterior thoracotomy on beating heart. METHOD: Minithoracotomy and direct coronary artery surgery without cardiopulmonary bypass (CPB) was attempted in 116 patients. The procedure was completed in 108 cases while in eight cases minithoracotomy was converted to mid sternotomy. In 107 cases, left internal mammary artery (LIMA) to left anterior descending (LAD) coronary artery anastomosis was done through left anterior minithoracotomy and in one case LIMA to LAD and right internal mammary artery (RIMA) to right coronary artery (RCA) anastomosis was done through bilateral minithoracotomy. Left anterior minithoracotomy through 4th intercostal space and right anterior minithoracotomy through 5th intercostal space was used for left and right internal mammary artery dissection respectively. With this approach 4-8 cm length of mammary artery was easily dissected. Mammary coronary artery anastomosis were performed on a beating heart without CPB through window pericardiotomy. Two patients also underwent left carotid endarterectomy along with LIMA to LAD anastomosis. In two patients complementary percutaneous transluminal coronary angioplasty (PTCA) to circumflex artery was done 5 days after minithoracotomy and LIMA to LAD anastomosis. RESULTS: Forty-two patients were extubated in the operating room and 66 in the intensive care unit 2-10 h after surgery. Blood transfusion was used in one case who was reexplored for postoperative bleeding due to a displaced hemoclip from the internal mammary artery branch. None of these patients required inotropic support. Postoperative predischarge check angiogram in 53 cases revealed adequate mammary coronary flow in 51 cases, the remaining two had anastomotic problems, one was subjected to PTCA and the other for redo coronary bypass grafting through mid sternotomy. Doppler flow assessment of anastomosis was done in 102 cases, of which two showed problems which was confirmed on check angiography. One-hundred and six patients are in our regular follow-up (mean follow-up 10+/-1.5 months), 98 of them are in functional class I. CONCLUSION: In our experience mammary coronary artery anastomosis without CPB through minithoracotomy is a safe, simple and minimally invasive procedure. Favorable cost/benefit ratio, has been achieved due to no early/late mortality and minimal early morbidity. Postoperative check angiogram and Doppler flow study revealed excellent mid term results.

Cardiopulmonary Bypass↗
PubMed1998

Detection of novel genes that are up-regulated (Di12) or down-regulated (T1A12) with disease progression in breast cancer.

Carcinogenesis is a multistep process and it is believed that seven to ten alterations are needed to convert a normal cell into a maligant one. Thus, identification of these specific genetic lesions and their role in the progression of cancer will lead to more effective methods for early diagnosis, as well as provide targets for treatment and therapeutic intervention. To isolate a number of genes that are differentially expressed in human breast carcinomas we used subtractive hybridization and differential display cloning techniques. By using these methods we obtained 952 clones, characterized 288 clones by restriction mapping, and 105 by Northern blotting and DNA sequencing. Twenty-four clones were found to be previously unidentified, unique genes. Full-length complementary (c)DNA was isolated from clone T1A12 and Di12, and further characterized by computer data search. Polyclonal antibodies were generated against N- and/or C-terminal peptides of the predicted T1A12 and Di12 amino acid sequences and immunohistochemistry was used to delineate gene function in breast cancers. We found that T1A12 is a novel member of the insulin-like growth factor binding protein family and that its expression decreases with disease progression. In 60 primary breast tissues examined, strong T1A12-specific immunoperoxidase staining was observed in luminal epithelial cells of normal lobules or ducts, and in blood vessels. Moderate protein expression was detected in hyperplastic and ductal carcinoma in situ (DCIS) cells, but no staining was found in invasive ductal carcinoma (IDC) cells. On the contrary, by using the same primary breast specimen Di12, a gene which shares no sequence homology with any protein, was found to be overexpressed in IDC cells but was not detectable in normal breast tissues. Specific strong Di12 staining was seen in the cytoplasm, with a slight increase in perinuclear regions of less well differentiated cells similar to those present in ductal carcinomas with poor prognosis. Both the T1A12 and Di12 genes, studied alone or in combination, could prove valuable for understanding the biology of breast cancer, detecting early and late stage disease, and for selecting appropriate treatments.

Breast Neoplasms↗
PubMed1998

Can academic radiology departments become more efficient and cost less?

PURPOSE: To determine how successful two large academic radiology departments have been in responding to market-driven pressures to reduce costs and improve productivity by downsizing their technical and support staffs while maintaining or increasing volume. MATERIALS AND METHODS: A longitudinal study was performed in which benchmarking techniques were used to assess the changes in cost and productivity of the two departments for 5 years (fiscal years 1992-1996). Cost per relative value unit and relative value units per full-time equivalent employee were tracked. RESULTS: Substantial cost reduction and productivity enhancement were realized as linear improvements in two key metrics, namely, cost per relative value unit (decline of 19.0% [decline of $7.60 on a base year cost of $40.00] to 28.8% [$12.18 of $42.21]; P < or = .001) and relative value unit per full-time equivalent employee (increase of 46.0% [increase of 759.55 units over a base year productivity of 1,651.45 units] to 55.8% [968.28 of 1,733.97 units]; P < .001), during the 5 years of study. CONCLUSION: Academic radiology departments have proved that they can "do more with less" over a sustained period.

Academic Medical Centers↗