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Biomedical subjects

R K Babayan

Publications and source records attributed to R K Babayan.

At least 37 records · Page 2Linked to original sources
PubMed1995

The impact of pneumoperitoneum, pneumoretroperitoneum, and gasless laparoscopy on the systemic and renal hemodynamics.

BACKGROUND: The use of therapeutic laparoscopy has become widespread recently. It is important to assess the effects of gaseous and gasless laparoscopy on systemic and renal hemodynamics. STUDY DESIGN: A prospective controlled animal study was performed on 40 well-hydrated pigs. Systemic and renal hemodynamics were monitored during peritoneal insufflation, retroperitoneal insufflation, and abdominal wall lifting for a period of two hours. A laser Doppler flow meter was applied laparoscopically to measure the renal cortical tissue perfusion. RESULTS: Peritoneal insufflation of carbon dioxide to a pressure of 15 mm Hg elicited transient elevations of the aortic pressure and carotid arterial blood flow. Unilateral pneumoretroperitoneum caused a smaller change on systemic hemodynamics. Pneumoperitoneum and pneumoretroperitoneum caused oliguria. Superficial renal cortical blood flow reduction decreased by an average of 60 percent in the compressed kidney, and blood flow returned to the pre-insufflation level after the pressure was released. A gradual decrease of tissue perfusion in the contralateral kidney and a concomitant gradual increase of the intra-abdominal pressure were observed when pneumo-retroperitoneum was maintained for two hours. No significant changes in urinary output and in systemic and renal hemodynamics were found when the abdominal wall was lifted up with a force equivalent to 15 mm Hg. CONCLUSIONS: Significant systemic and renal hemodynamic changes were elicited in gaseous but not in gasless laparoscopy, which may explain the decreased urinary output observed during gaseous laparoscopy. Pneumoperitoneum caused greater systemic and renal hemodynamic alterations than pneumoretroperitoneum; however, the effects were transient and reversible after a period of two hours.

Animals↗
PubMed1994

Radical prostatectomy for adenocarcinoma of the prostate: the influence of preoperative and pathologic findings on biochemical disease-free outcome.

OBJECTIVE: This retrospective study evaluated the outcome for a cohort of men undergoing radical retropubic prostatectomy alone as primary treatment for clinical T1-2 prostate adenocarcinoma. METHODS: Sixty-two patients treated at Boston University Medical Center between 1987 and 1992 underwent radical prostatectomy alone without adjuvant or neoadjuvant endocrine therapy. Actuarial and multivariate analyses were made of disease-free outcome according to preoperative tumor T stage, prostate-specific antigen (PSA), and biopsy grade, and according to the pathologic findings at surgery. Recurrence was defined as the persistence or recurrence of detectable serum PSA four or more weeks following surgery. RESULTS: Of all patients judged clinically to have localized disease (T1-2), 52 percent proved to have pathologic T3 tumors. Of these, 81 percent had positive surgical margins. The strongest preoperative predictors of pT3 disease were the biopsy Gleason grade and the initial serum PSA value. Actuarial analysis showed the overall likelihood of remaining free from detectable PSA at four years to be 43 percent (75% for those with organ-confined disease and 27% for those who were pT3). The poorest prognosis was seen in those with seminal vesicle involvement. Biopsy Gleason grade and initial PSA were independent preoperative predictors of biochemical failure in a Cox regression analysis but clinical T stage was not. CONCLUSIONS: The biopsy Gleason grade and initial PSA were identified as strong preoperative predictors of disease-free outcome. We confirmed the favorable prognosis of men with organ-confined disease, but emphasize the high likelihood of relapse in those with positive surgical margins or seminal vesicle invasion.

Adenocarcinoma↗
PubMed1994

Effects of intra-abdominal pressure on renal tissue perfusion during laparoscopy.

An animal model was established to study the effects of elevated intra-abdominal pressure (IAP) on systemic and renal hemodynamics during laparoscopy. In a pilot study in five dogs, we simultaneously recorded carotid artery blood flow (CABF), carotid artery blood pressure (CABP), inferior vena caval pressure (IVCP), renal parenchymal blood flow, and IAP. The renal parenchymal blood flow was measured by a laser Doppler flowmetry (LDF) needle probe and the renal artery blood flow by an ultrasonic Doppler probe, both placed through laparotomy. The reliability and reproducibility of these two measurements at different renal perfusion pressures were documented. The established method was then used to assess the effects of increased IAP on renal hemodynamics during laparoscopy in six pigs. Pneumoperitoneum was achieved by insufflating the abdominal cavity with air. The LDF needle probe was inserted into the renal parenchyma laparoscopically. An increase in IAP from 0 to 40 mm Hg did not influence CABP. However, significant decreases in CABF were seen from 190.8 +/- 59.5 mL/min at 0 mm Hg IAP to 169 +/- 43.6 mL/min at 15 mm Hg. The CABF decreased in a linear fashion as IAP was increasing (correlation coefficient R = 0.976). Renal cortical blood flow (RCBF) decreased from 50.1 +/- 17.7 mL/min per 100 g at 0 mm Hg to IAP to 21.2 +/- 9.6 mL/min per 100 g of tissue at 15 mm Hg. There was an exponential correlation between IAP and RCBF (R = 0.897).(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1993

Managing prostate cancer. Part II: Disseminated disease.

Each year in the United States, approximately 100,000 men are found to have prostate cancer. Of these, about half show evidence of bony metastases at the time of presentation. Each year, too, some 30,000 American men die of prostate cancer. Conceptually, the treatment of metastatic prostate cancer has changed little in the 50 years since Charles B. Huggins and Clarence V. Hodges discovered the hormone-dependent nature of prostate cancer cells. Still, as the years have passed, several therapeutic options have become available. For the most advanced cases, treatment centers on relief of urinary obstruction and amelioration of the pain of bony metastases, along with vigilance for the potentially disastrous sequelae of acute neurologic change due to spinal fractures. In Part I of this article, which appeared in the April 15 issue of Hospital Practice, we discussed the assessment and management of localized carcinoma of the prostate. In this part, the focus shifts to disseminated disease (Figure 1). We again present two cases representing distinctly different points on the spectrum of disease and discuss how management would proceed in each case. This strategy affords an opportunity to review the various available treatment options, with their advantages and drawbacks.

Adenocarcinoma↗
PubMed1993

Transurethral ultrasound-guided laser-induced prostatectomy: National Human Cooperative Study results.

Between November 1990 and March 1992, 150 patients at 10 United States institutions were treated with transurethral ultrasound-guided laser-induced prostatectomy (TULIP) for the relief of bladder outlet obstruction secondary to benign prostatic hypertrophy. The TULIP system incorporates ultrasound visualization with a 90-degree angle, side-firing laser to effect coagulation necrosis of prostate tissue. The overall preoperative prostate volume in this TULIP study was 40 cc and all types of prostatic enlargement, including median lobe obstruction, were treated. There were no intraoperative complications, with no hemorrhage or post-transurethral resection syndrome, and no blood transfusions were required. Hospital stay averaged 1.7 days and 83% of the patients went home after a 1-night stay. We evaluated 63 patients at 6 months after the TULIP procedure. Mean symptom scores decreased from 18.8 to 6.1, for a 68% improvement. The mean peak flow increased from 6.7 ml. per second preoperatively to 11.9 ml. per second, for a 78% improvement. Overall, 87% of the patients exhibited at least 50% improvement in either the symptom score or peak flow parameter, while 49% of the patients demonstrated at least a 50% improvement in both parameters.

Equipment Design↗
PubMed1993

Stents and catheters in percutaneous renal surgery.

Ureteral stents are commonly used either briefly or long term after percutaneous renal surgery. Most percutaneous stone procedures do not necessitate a ureteral stent, but stenting is advisable if there has been extensive trauma, perforation, or ureteropelvic junction obstruction by a large calculus. Stenting after endopyelotomy is routine, and the author has found it helpful to insert a 5F to 7F stent for 5 to 7 days preoperatively to dilate the ureter. The author reviews the available nephrostomy tubes and nephrostomy-ureteral stents, including the tamponade catheter.

Humans↗
PubMed1992

Comparison of a pulsed dye laser and electrohydraulic lithotripsy on porcine gallbladder and common bile duct in vitro.

With the advent of minimal access biliary procedures there is a need for a safe intracorporal lithotripsy technique that can be used through small flexible endoscopes. Currently, the two techniques available are electrohydraulic lithotripsy and laser induced shock wave lithotripsy. In this study we compare the effect of a 504 nm coumarin pulsed dye laser and electrohydraulic lithotripsy on in vitro porcine gallbladder and common bile duct. Electrohydraulic lithotripsy at the lowest energy the generator would deliver caused perforation of both tissues in only a few pulses when a 1.9-F probe was placed in direct contact with the tissue. Energy from a 504 nm coumarin pulsed dye laser delivered through a 320-microns fiber placed in light contact with the tissue caused an energy-dependent perforation after 50 pulses in from none to 44% of tissues. It was also found that there was a higher incidence of perforation in more vascular than non-vascular tissue. When the EHL probe and the laser fiber were held 1-2 mm from the tissue surface, discharge of each resulted in no perforation. On histological examination of the tissues, the perforations were found to be very small with laser lithotripsy and considerably larger with the electrohydraulic lithotripsy. It was felt that laser lithotripsy in the clinical situation was likely to be much safer than electrohydraulic lithotripsy.

Animals↗
PubMed1991

Primary angiosarcoma of the seminal vesicle.

We report on an unusual case of primary angiosarcoma of the seminal vesicle. Diagnosis was confirmed by light and electron microscopy, as well as specific immunohistochemical staining. This rare tumor is highly aggressive, and refractory to traditional surgical and adjuvant therapeutic modalities. Sarcomatous lesions of the seminal vesicle are reviewed.

Brain Neoplasms↗
PubMed1991

Acquired renal cystic disease: implications for the urologist.

Acquired cystic kidney disease has become increasingly recognised as a significant risk in patients with end-stage renal disease, especially in those maintained on chronic haemodialysis and peritoneal dialysis. A review of the literature indicates that nearly 50% of patients on dialysis for more than 3 years develop renal cystic changes. The major complications of this condition are neoplasia and spontaneous renal haemorrhage. The risk of developing renal carcinoma has been estimated to be more than 30 times higher in dialysis patients with cystic changes than in the general population. Our experience with 5 patients is reported, including 3 with renal tumours and 1 with metastatic disease. Careful surveillance of dialysis patients using yearly ultrasonography and computed tomography is recommended. The evolving indications for radical nephrectomy in this disease are discussed.

Female↗
PubMed1990

Effect of autolymphocyte therapy on survival and quality of life in patients with metastatic renal-cell carcinoma.

To assess the value of autolymphocyte therapy (ALT) in the treatment of metastatic renal-cell carcinoma, 90 patients were randomised to receive every month for six months oral cimetidine plus an infusion of autologous peripheral blood lymphocytes activated in vitro by a previously generated autologous lymphokine mixture, or cimetidine alone. The median follow-up was 15 months. Survival time for the autolymphocyte group was approximately 2.5 times that for the cimetidine group (p = 0.008). Patients who had greater than 500 pg interleukin-1 (IL-1) per ml autologous lymphokine mixture had a six-fold survival advantage over those with less than 500 pg/ml (p less than 0.00005). Men treated with ALT had a four-fold survival advantage (p = 0.001) over men who received cimetidine only. Infusion of the cultured autolymphocytes was accompanied by mild, self-limited fever in 11 of the 45 ALT patients, and by only one instance in which fever was accompanied by tachypnoea and hypotension.

Actuarial Analysis↗
PubMed1990

Triamterene nephrolithiasis: renewed attention is warranted.

Although triamterene has been known to contribute to urinary calculus formation, it has been presumed to be a rare phenomenon. Our review of stone analyses performed during the last decade by a single laboratory reveals an increasing incidence of triamterene stones. Awareness of the calculogenic potential of triamterene-containing medications should be re-emphasized.

Humans↗
PubMed1989

Discordant human chorionic gonadotropin results giving rise to inappropriate therapy in a case of testicular cancer.

The most widely cited cause of a falsely elevated human chorionic gonadotropin level in patients with germ cell tumors is an elevated level of partially cross-reacting luteinizing hormone. Other causes of discordant human chorionic gonadotropin results (human chorionic gonadotropin elevated in 1 assay but normal in others) in testicular cancer have received scant attention. A patient with pure seminoma was given inappropriate chemotherapy on the basis of an elevated human chorionic gonadotropin level, later shown to be due to a nonspecific serum interfering substance. A discordant human chorionic gonadotropin result should be suspected when the human chorionic gonadotropin is only modestly elevated, there is no serial increase in the human chorionic gonadotropin level and no other evidence of tumor can be found.

Adult↗
PubMed1988

Thrombin: implications for intratumor therapy against metastasis.

The effect of an intratumor injection of thrombin as a potential cancer therapeutic agent was examined in two transplantable solid tumor models: a renal adenocarcinoma implanted beneath the kidney capsule in Wistar-Lewis rats and a rhabdomyosarcoma implanted similarly in Wag-Rij rats. For each tumor type, a group of test animals received a single dose of thrombin injected directly into the central tumor mass 6 weeks following tumor implantation. Corresponding groups of tumor-implanted controls consisted of animals that received an equal volume injection of saline instead of thrombin and animals that were not injected. The tumor-implanted animals receiving thrombin, saline, or no injection were handled identically. The saline-injected and noninjected control animals died of metastasis to the lung within the same well-defined period of time. All animals receiving thrombin showed significantly increased longevity, and the degree of increase was related to variations in tumor size at the time of injection. In every case, animal death was due to pulmonary metastasis verified at autopsy, but animals receiving thrombin therapy lived about 85% longer following tumor implantation than animals not receiving therapy.

Animals↗
PubMed1988

Safety and efficacy of electrohydraulic lithotripsy by ureteroscopy.

Electrohydraulic lithotripsy, when performed blindly for ureteral calculi in the past, resulted in frequent ureteral perforation and, therefore, it was considered to be unsafe. A total of 33 patients from 5 institutions underwent electrohydraulic lithotripsy for ureteral calculi under direct vision. There were only 3 minor ureteral perforations treated by ureteral catheter drainage. All patients were free of stones after treatment and there were no long-term complications. Electrohydraulic lithotripsy by ureteroscopy is considered to be a safe and effective method for fragmentation and removal of large ureteral calculi.

Adult↗