Biomedical subjects

Mani Menon

Publications and source records attributed to Mani Menon.

61 records · Page 4Linked to original sources

PubMed2002

Technique of da Vinci robot-assisted anatomic radical prostatectomy.

OBJECTIVES: Robotic radical prostatectomy is a new procedure for treating prostate cancer. Many centers are attempting this new modality but a detailed description of the technique has not yet been published. We report the technique as performed at the Vattikuti Urology Institute. METHODS: At Vattikuti Urology Institute, we have performed more than 30 such operations and have standardized the technique for safe and reproducible treatment of prostate cancer. We collected the patient data and surgical logs to improve and standardize this procedure. We recorded the operation and made relevant modifications after reviewing the recordings to improve the outcome. RESULTS: The operation was developed on the scientific foundations of anatomic radical prostatectomy as described by Walsh and the laparoscopic prostatectomy developed at Montsouris. Our technique differs from these procedures because of the need for two surgical teams and the use of fine, endo-wrist instruments with three-dimensional stereoscopic visualization. We describe the patient setup, positioning, port placement, preparation of the robot, docking of the arms, and the surgical steps of performing anatomic prostatectomy with robotic assistance. CONCLUSIONS: This report describes the current technique of robotic prostatectomy as developed at the Vattikuti Urology Institute.

Humans↗

PubMed2002

Prospective comparison of radical retropubic prostatectomy and robot-assisted anatomic prostatectomy: the Vattikuti Urology Institute experience.

OBJECTIVES: Robotic assistance may enhance the precision of anatomic dissection and increase the feasibility of performing laparoscopic radical prostatectomy for most surgeons. We performed a prospective comparison of 30 consecutive patients undergoing conventional radical retropubic prostatectomy (RRP) and 30 initial patients undergoing robot-assisted anatomic prostatectomy (RAP) at our institution. METHODS: The study design was a prospective nonrandomized comparison of anatomic RRP performed using the technique of Walsh and RAP performed with the da Vinci surgical system. We evaluated the baseline patient and tumor characteristics (age, body mass index, serum prostate-specific antigen, Gleason score, and clinical stage), intraoperative parameters (operative time, blood loss, and need for transfusion), postoperative parameters (pain score, hospitalization duration, catheter duration), histopathologic parameters, and complications in the two groups. RESULTS: The preoperative parameters were comparable for both groups of patients. The mean setup time for RAP was 0.95 hours. The mean operating time was 2.3 hours for RRP and 4.8 hours for RAP (P <0.001). One patient required conversion from RAP to RRP because of a lack of progress. The mean blood loss was 970 mL for RRP and 329 mL for RAP (P <0.001). The drop in hemoglobin was greater in the RRP group (4.4 versus 1.2 g in RAP; P <0.05). The mean pain score on postoperative day 1 was 7 in the RRP group and 4 in RAP group (P = 0.05). The mean hospital stay was 56 hours in the RRP group and 36 hours in the RAP group (P value not significant). Sixty-three percent of the RAP and 0% of the RRP groups were discharged within 23 hours (P <0.001). The mean duration of postoperative catheterization was 14 days for the RRP and 11 days for the RAP groups (difference not significant). The pathologic stage, margin status, and prostate-specific antigen values were not different between the two groups. The setup time, operative time, blood loss amount, and catheterization duration were significantly reduced after the first 20 patients. CONCLUSIONS: Currently, RAP is a longer procedure than RRP. However, the blood loss is minimal and patients feel less pain and are discharged earlier from the hospital. In our hands, the margin status and complication rates were comparable for both techniques.

Aged↗

PubMed2002

Effects of oxalate on the re-initiation of DNA synthesis in LLC-PK1 cells do not involve p42/44 MAP kinase activation.

BACKGROUND: Oxalate interaction with renal epithelial cells results in a program of events that include alterations in gene expression, re-initiation of DNA synthesis, cell growth and apoptosis. Our studies focused on understanding the mechanisms involved in the oxalate-induced re-initiation of the DNA synthesis. The effects of oxalate alone or in combination with epidermal growth factor (EGF), platelet-derived growth factor (PDGF) and insulin were investigated to determine whether oxalate utilized the p42/44 mitogen activated protein (MAP) kinase pathway, which is a common pathway used by a majority of the mitogens. METHODS: LLC-PK1 cells (a renal epithelial cell line of porcine origin) were exposed to oxalate in the presence or absence of three established growth factors, EGF, insulin and PDGF, and of the transcription/translation inhibitors, actinomycin-D and cycloheximide. DNA synthesis was assessed by [3H]-thymidine incorporation. p42/44 MAP kinase activity was assessed by super-shift analysis as well as by immunocomplex kinase assay. RESULTS: Exposure of growth-arrested LLC-PK1 cells to oxalate resulted in the re-initiation of the DNA synthesis was abolished by [corrected] pretreatment with transcription/translation inhibitors. Oxalate (1 mmol/L), EGF (50 ng/mL) and insulin (100 ng/mL) stimulated DNA synthesis in growth-arrested LLC-PK1 cells, while PDGF (50 ng/mL) had no effect. Effects of EGF and oxalate on DNA synthesis were additive. In contrast, oxalate and insulin had antagonistic effects on DNA synthesis. Additionally, oxalate did not activate the p42/44 MAP kinase pathway while EGF stimulated this pathway. CONCLUSIONS: These findings demonstrate that oxalate does not activate the p42/44 MAP kinase pathway, and the effects of oxalate are mediated by pathways that are distinct from those of EGF, PDGF and insulin.

Animals↗

PubMed2002

Relevant patient and tumor considerations for early prostate cancer treatment.

Prostate cancer remains the most commonly diagnosed noncutaneous malignancy in American men. Currently, there are 3 standard treatment options available to men with early prostate cancer: expectant management, radiation therapy, and radical prostatectomy. Although a number of studies have evaluated survival after treatment for early prostate cancer, the optimal choice of therapy for any given patient remains a difficult decision and requires the consideration of a variety of patient and tumor factors. The final selection of therapy for early prostate cancer should be based on an informed discussion between the physician and patient. To accomplish this goal, patients must be made familiar with the pertinent factors that affect survival. We review the factors most relevant for patients to understand as they consider their treatment options for early prostate cancer and summarize the data for physicians who counsel them.

Age Factors↗

PubMed2002

Prognostic impact of histologic subtyping of adult renal epithelial neoplasms: an experience of 405 cases.

Just two and a half decades ago adult renal cell neoplasms, i.e., those arising from the renal tubules or collecting duct epithelium, were subdivided into two major subtypes: "clear cell carcinoma" and "granular cell carcinoma." Subsequent detailed morphologic and/or cytogenetic studies have resulted in the recognition of several distinctive subtypes of adult renal epithelial neoplasms, which has led to the promulgation of a refined contemporary histologic classification of these tumors. This study examines the prognostic significance of histologic subtyping in accordance with the new classification in a consecutive series of 405 cases treated at a single institution. Cases were histologically classified into 28 (7%) benign tumors [27 (6.7%) renal oncocytomas, 1 (0.2%) metanephric adenoma] and 377 (93%) malignant tumors [255 (63%) conventional (clear cell) renal cell carcinoma, 75 (18.5%) papillary renal cell carcinoma, 24 (5.9%) chromophobe renal cell carcinoma, and 23 (5.7%) renal cell carcinoma, unclassified]. A total of 25 (6.6%) malignant tumors showed evidence of sarcomatoid change. Kaplan-Meier survival analysis with log-rank test showed histologic type (p = 0.002), Fuhrman's nuclear grade (p = 0.001), TNM stage (p = 0.001), vascular invasion (p = 0.001), and necrosis (p = 0.001) to be significantly associated with disease-specific survival and progression-free survival, based on follow-up of 368 patients (mean 64.5 months, median 56 months). The 5-year disease-specific survival for chromophobe renal cell carcinoma, papillary renal cell carcinoma, conventional (clear cell) renal cell carcinoma, and renal cell carcinoma, unclassified was 100%, 86%, 76%, and 24%, respectively; no patient with a benign tumor diagnosis progressed or died of disease. The 5-year progression-free survival for chromophobe renal cell carcinoma, papillary renal cell carcinoma, conventional (clear cell) renal cell carcinoma, and renal cell carcinoma, unclassified was 94%, 88%, 70%, and 18%, respectively. Malignant tumors with sarcomatoid change had a 35% and 27%, 5-year disease-specific and progression-free survival, respectively. Cox proportional hazards regression analysis showed TNM stage (p = 0.001), nuclear grade (p = 0.01), and necrosis (p = 0.05) to be significant predictors of disease-specific survival. In conclusion, our study shows that the histologic categorization of adult renal epithelial neoplasms performed by routine light microscopic hematoxylin and eosin-based examination in accordance with the contemporary classification scheme has prognostic utility.

Adenoma, Oxyphilic↗

PubMed2002

Effects of oxalate on HK-2 cells, a line of proximal tubular epithelial cells from normal human kidney.

PURPOSE: Oxalate, a metabolic end product, is a major constituent of majority of renal stones. Previous studies with LLC-PK1 cells, a line of proximal renal epithelial cells of porcine origin, have shown that oxalate produces time and concentration dependent effects on the growth and viability of these cells. We assessed the possibility that oxalate may be toxic to HK-2 cells, a line of human proximal renal epithelial cells. MATERIALS AND METHODS: HK-2 cells were maintained in Dulbecco's modified Eagle's medium supplemented with fetal bovine serum and antibiotics. Cells were exposed to oxalate for various intervals. Trypan blue exclusion criteria were used to assess membrane integrity, cell morphology was assessed by hematoxylin and eosin staining and crystal violet staining was used to measure cell density. DNA synthesis was measured by [3H]-thymidine incorporation and superoxide production was measured by the nitroblue tetrazolium reduction method. RESULTS: Exposure of HK-2 cells to oxalate produced time and concentration dependent increase in the membrane permeability to trypan blue and changes in the light microscopic appearance of the cells. Long-term exposure to oxalate resulted in an increase in DNA synthesis and alterations in cell viability with net cell loss after exposure to high oxalate concentrations. CONCLUSIONS: To our knowledge the results provide the first direct demonstration of the toxic effects of oxalate in HK-2 cells, a line of human renal epithelial cells, and suggest that hyperoxaluria may contribute to renal tubular damage associated with calcium oxalate stone disease.

Cell Division↗

PubMedDate not supplied

Autologous tunica vaginalis and subcapsular orchiectomy: a hormonal therapy for prostate cancer.

Two novel surgical procedures that combine an autologous tunica vaginalis pedicle graft (TVG) with a subcapsular orchiectomy (SCOT) were evaluated in asymptomatic patients with rising prostate-specific antigen (PSA) values following radiation therapy, a radical retropubic prostatectomy, or a newly diagnosed prostatic cancer with bony metastasis. In the SCOT I procedure, the TVG was secured to the inner wall of the tunica albuginea. In the SCOT II procedure, the TVG was folded and secured to the external wall of the tunica albuginea. Between December 1, 1999, and July 1, 2000, 26 patients were offered hormonal therapy. Twelve patients selected the SCOT I procedure, 12 selected a luteinizing hormone-releasing hormone (LHRH) agonist, and 2 selected a bilateral total orchiectomy (BTO). Because the cosmetic outcome of the SCOT I procedure was less than ideal, this procedure was modified in December 2001. Between December 1, 2001, and July 1, 2002, 28 hormonal candidates were evaluated. Twelve patients selected the SCOT II procedure, 11 selected an LHRH agonist, and 5 selected a BTO. Preoperative measurements of the testicular area and PSA were obtained. During postoperative visits, the total testosterone, PSA, and testicular area were determined, and the Fugl-Meyer questionnaire (FMQ) and SCOT-specific questionnaire (SSQ) were completed. Between March 1, 2000, and December 1, 2002, 10 patients underwent a BTO. This group was the control for the postoperative SCOT total testosterone values. Sixty-three percent of the mean preoperative testicular area was preserved in the SCOT II group vs 43% in the SCOT I group at the 9- to 12-month visit (P <.01). The mean postoperative total testosterone values for the SCOT I, SCOT II, and BTO groups were in the castrate range. No statistically significant difference was noted between the preoperative and postoperative FMQ scores among the SCOT I and SCOT II groups. Eighty-three percent of the SCOT II patients experienced no change in masculine identity, and 58% noted no change in testicular size. One hundred percent of the SCOT I patients experienced no change in masculine identity and noted no change in testicular size. The SCOT II procedure preserved a greater testicular area than the SCOT I. Both SCOT procedures achieved castrate levels of total testosterone and maintained masculine identity in 83%-100% of patients.

Aged↗