PubMed Health⌕ Search

Biomedical subjects

S A Kahn

Publications and source records attributed to S A Kahn.

12 recordsLinked to original sources
PubMed2000

Clinical effectiveness of new stent design: randomized single-blind comparison of tail and double-pigtail stents.

BACKGROUND AND PURPOSE: Stent morbidity appears to be secondary to lower urinary tract irritation. In an effort to decrease stent morbidity, a "one size fits all" Tail stent (Microvasive [Boston Scientific] Natick, MA) was developed with a 7F proximal pigtail and 7F shaft which tapers to a lumenless straight 3F tail. PATIENTS AND METHODS: We randomized 60 patients in a single-blind fashion to a 7F tail stent or 7F double-pigtail Percuflex stent. Patients were evaluated at the time of stent removal and 2 weeks later with a standardized questionnaire assessing: irritative lower tract symptoms individually and on a total scale of 0 (no symptoms) to 30 (worst symptoms), obstructive lower tract symptoms (on a total scale of 0-20), and upper tract irritative symptoms (on a total scale of 0-10). RESULTS: Patient age, weight, and height were similar in the two groups. Complications, including fever, urinary tract infections, emergency room visits, and the need for antispasmodics and pain medication, also demonstrated no significant difference. At the time of stent removal, patients who received a tail stent had significantly less urinary frequency and a statistically significant (21%) decrease in overall irritative voiding symptoms (12.2 v 15.4; p = 0.048). Two weeks after stent removal, the total irritative voiding symptoms was markedly decreased in both groups (7.1 in the Tail v 5.3 in the double-pigtail group; p = 0.15). Obstructive bladder and flank symptoms were not significantly different in the two stent groups, either at the time of stent removal or at 2 weeks after removal. CONCLUSION: In this randomized, single-blind study, the 7F Tail stent produced significantly less irritative symptoms than did the standard 7F double-pigtail stent. Obstructive symptoms tended to be less with the new stent, while flank symptoms were similar.

Adult↗
PubMed1999

Mechanism of ureteral stent flow: a comparative in vivo study.

BACKGROUND AND OBJECTIVES: The flow characteristics of ureteral stents have yet to be clearly defined. In this study, flow mechanics were studied in several silicone-based stents including 4.8F, 7F, and 10.3F pigtail; 7F Tower; and a prototype mesh stent. MATERIALS AND METHODS: Forty-five female Yucatan minipigs underwent bilateral laparoscopic occlusion of their renal vessels to stop urine production. A nephrostomy tract was established by retrograde puncture. A stent was placed in the ureter, and three measurements were taken with flow from a bag of irrigant 20 cm above the kidney: stent occluded with a guidewire (extraluminal flow), stent unobstructed (total flow), and laparoscopically placed extraureteral ligature (luminal flow). RESULTS: Luminal flow and, to a lesser extent, total flow appeared to increase as the internal and external diameters of the stent increased. The Tower stent, which had no sideholes, had much lower flow rates in all categories, while the prototype mesh stent showed greater total flow compared with the other stents. Extraluminal flow did not increase with stent size greater than 7F. CONCLUSIONS: Luminal flow, but not extraluminal flow, increased with an increase in the internal diameter of the stent. In general, the least favorable flow occurred with a Tower stent, which had the smallest internal diameter. The greatest flow was seen with the prototype mesh stent.

Animals↗
PubMed1998

An open study on the efficacy and safety of transurethral needle ablation of the prostate in treating symptomatic benign prostatic hyperplasia: the University of Florida experience.

PURPOSE: We determine the safety and efficacy of transurethral needle ablation of the prostate in patients with moderate to severe symptoms of benign prostatic hyperplasia. MATERIALS AND METHODS: Transurethral needle ablation of the prostate was performed on 45 consecutive patients. For an average prostate of 2.5 to 3 cm. long treatments were performed in 2 separate planes at 4 quadrants (2, 4, 8 and 10 o'clock positions) each. The 2 planes were 1 cm. below the bladder neck and 1 cm. proximal to the verumontanum. For prostatic urethral lengths longer than 3 cm. a treatment plane was added for each additional centimeter of prostatic urethra. The procedure was performed in 26 patients under local anesthesia using 20 cc 2% intraurethral lidocaine gel (11) or supplemented with intravenous 1.25 to 5 mg. midozolam (15). Of these patients 2 had a supplemental perineal block using a mixture of equal amounts of 15 cc 2% lidocaine without epinephrine and 0.25% bripivacaine, 10 underwent the procedure under general anesthesia, 2 had epidural and 4 had spinal anesthesia, and 3 had managed anesthesia care. Mean length of each procedure was 79 minutes (range 50 to 240). All procedures were done on an outpatient basis and patients were released on the same operative day. RESULTS: Mean prostatic volume on transrectal ultrasound was estimated at 48.1 cc (range 20 to 185). Following treatment the International Prostate Symptom Score decreased from a mean of 20.9 at baseline to 15.4 at 1 month, 16.1 at 3 months, 10.7 at 6 months and 9.9 at 1 year. The peak flow rate improved from a baseline mean of 8.3 to 13.4 at 3 months, 13.1 at 6 months and 14.9 at 1 year. The quality of life score improved from a baseline of 4.8 to 3.5, 2.2, 2.5 and 1.03 at 1, 3, 6 and 12 months, respectively. Of the 2 patients in whom the procedure failed; 1 required a bladder neck incision at 3 months and the other transurethral resection of the prostate. Foley catheters were left in place in all patients for an average of 4.85 days. CONCLUSIONS: After a followup of up to 12 months we conclude that transurethral needle ablation of the prostate is an effective treatment for symptomatic benign prostatic hyperplasia. This procedure has minimal morbidity, is less costly than conventional transurethral resection of the prostate and can be performed as an outpatient office procedure under local anesthesia in a significant number of patients.

Aged↗
PubMed1997

Contribution of endothelin-1 to renal vasoconstriction in unilateral ureteral obstruction: reversal by verapamil.

PURPOSE: In unilateral ureteral obstruction (UUO) vasoconstriction occurs both during and after release of UUO. ET-1, an endogenous peptide, causes marked vasoconstriction mediated by an increase in cytosolic calcium. We measured renal output of endothelin-1 (ET-1) in dogs with UUO and examined if the renal vasoconstriction that persisted after release of UUO could be reversed by a calcium antagonist, verapamil. MATERIALS AND METHODS: Hemodynamic and clearance experiments were performed in anesthetized mongrel dogs in three groups. Group I consisted of 9 dogs with sham-operation. Group 2 consisted of 7 dogs in whom ureteral obstruction was released 1.9 hours after UUO. Group 3 consisted of 5 dogs in whom verapamil was infused into the renal artery at two doses (5 and 10 microg./min., respectively) after release of UUO of 19-hour duration. ET-1 concentrations (measured by radioimmunoassay) were determined for renal venous and arterial plasma. RESULTS: In Group 1 renal venous plasma ET-1 level was 16.7 +/- 2.2, significantly lowered than 22.8 +/- 3.2 pg./ml. in arterial plasma, indicating a net clearance of ET-1. In Group 2 and 3, renal venous plasma ET-1 levels (28.2 +/- 5.2 and 27.2 +/- 2.4 pg./ml., respectively) were significantly greater than those in arterial plasma (24.2 +/- 5.7 and 17.4 +/- 0.8 pg./ml., respectively), indicating a net output of ET-1 in the kidney, In addition, renal vasoconstriction occurred in Groups 2 and 3 as indicated by significantly lower renal blood flow and GFR than those in Group 1. In Group 3, intrarenal infusion of verapamil at two doses did not change arterial pressure but caused an ipsilateral, significant increase in RBF (from 132 +/- 4 17 to 1.84 +/- 19 and 180 +/- 16 ml./min., respectively) and dose-dependent increases in GFR (from 12 +/- 2 to 25 +/- 3 and 38 +/- 7 ml./min., respectively), associated with a profound dose-dependent ipsilateral diuresis and natriuresis. CONCLUSION: Profound renal vasoconstriction in UUO was associated with an increase in renal production of ET-1, possibly contributing to renal vasoconstriction, and was reversed by intrarenal infusion of verapamil.

Animals↗
PubMed1994

Osteoporosis and genetic influence: a three-generation study.

We have studied 27 triads of mother, daughter and grandmother for possible genetic influence on distal and proximal forearm bone density, measured by single photon absorptiometry. We found a significant correlation of bone density at the proximal forearm between the mothers and grandmothers (r = 0.499, P < 0.01). There was also a weak correlation between proximal forearm bone densities of mothers and daughters (r = 0.327, P < 0.1). Significant correlations were found between the three generations for grip strength, pedometry, height and triceps skinfold thickness. There was also significant correlation between mother and grandmother for alcohol intake. There was no correlation for contraceptive pill use, smoking, dietary calcium intake, body weight or body mass index. The study concludes that, although there are similarities in bone mineral content between the three generations, genetic factors cannot be conclusively proven to be the major determinant of bone density. Lifestyle and environmental factors may have a bearing on achieving the peak bone mass and subsequent development of osteoporosis.

Absorptiometry, Photon↗
PubMed1986

Hepatic disorders in the acquired immune deficiency syndrome: a clinical and pathological study.

We reviewed the clinical data, hepatic histology, and microbiological features of 21 patients with previously documented acquired immune deficiency syndrome who had liver biopsies. Diagnoses of specific infections were made on liver biopsy in 11/21 patients (57%). Granulomas were found in 10/21 patients (48%) and were most often a manifestation of infection with Mycobacterium avium-intracellulare. Elevated levels of serum alkaline phosphatase and longer duration of diagnosed illness were significantly associated with the presence of granulomatous disease.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Local area networks and the hospital.

Hospital information systems are characterized by their complexity of individual functions, heterogeneity of functions, and dependence upon integration. A distributed computerized information system is well suited to meeting the needs of hospitals. A local area communications network (LACN) removes a major impediment to the use of distributed systems. An advanced microprocessor-based LACN using fiberoptic communications has been developed by the Applied Physics Laboratory of The Johns Hopkins University and has been implemented at the University of California, San Francisco Hospital.

California↗
PubMed1982

A prototype generalized network technology for hospitals: initial implementation.

A demonstration implementation of a distributed data-processing hospital information system using an intelligent local area communications network (LACN) technology is described. This system is operational at the UCSF Medical Center and integrates four heterogeneous, stand-alone minicomputers. The applications systems are PID/Registration, Outpatient Pharmacy, Clinical Laboratory, and Radiology/Medical Records. Functional autonomy of these systems has been maintained, and no operating system changes have been required. The LACN uses a fiber-optic communications medium and provides extensive communications protocol support within the network, based on the ISO/OSI Model. The architecture is reconfigurable and expandable. This paper describes system architectural issues, the applications environment, and the local area network.

California↗