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Biomedical subjects

R M Weiss

Publications and source records attributed to R M Weiss.

At least 181 records · Page 10Linked to original sources
PubMed1980

Effect of age on contractility of guinea pig ureter.

Longitudinal force-length relationships of guinea pig ureter were studied in vitro in animals 3 weeks, 3 months, and 3 years of age. Distal segments of 3-week-olds underwent a greater per cent increase in length in response to an applied resting force than those from older age groups. Resting force-length relations of proximal segments were unaffected by age. Active force was higher in distal segments at all ages and at all lengths. Maximum active force increased with age. The increase in force developed between 3 weeks and 3 months of age seemed to be attributable to an increase in contractility since there was an associated increase in active stress; the increase developed between the 3-month- and 3-year-olds was associated with increased muscle cross-sectional area but with no change in active stress. This finding suggests that no change in contractility occurred during this time interval.

Aging↗
PubMed1979

Ultrasound evaluation of bladder calculi.

A case is presented in which the identification of intravesical calculi by ultrasound was an aid in management. Bladder stones appear as high intensity echoes within the bladder, have an associated acoustic shadow and shift to the dependent portion of the bladder with alterations in position. Ultrasound provides a rapid, safe imaging technique to diagnose or verify the presence of bladder calculi.

Child, Preschool↗
PubMed1979

Results of biopsy after early stage prostatic cancer treatment by implantation of 125I seeds.

We have treated 77 patients for clinically early stage carcinoma of the prostate, 9 stage A2, 63 stage B and 5 stage C, with direct implantation of 125I seeds into the prostate and pelvic lymphadenectomy. It is estimated that a minimum dose of 15,000 rad but a maximum dose of 35,000 rad is delivered to the prostate over several months. Of the 77 patients 14 (18 per cent) had metastatic disease in the pelvic lymph nodes. In 22 cases perineal needle biopsy was done 12 to 18 months after treatment and in 3 cases a second biopsy was performed after 2 to 3 years. Persistent tumor was present in 11 biopsies. Cytological changes were observed in 8 of these, primarily cytoplasmic vacuolation and nuclear pyknosis. There seemed to be no relationship between grade and stage of disease and histological evidence of persistence of tumor after radiation. One patient with persistent tumor in the postoperative biopsy has shown progression of disease after 2 years and another with a negative biopsy has a bony metastasis. The remaining 10 patients with persistent tumor have shown no sign of progression of disease during a 2 to 4-year interval.

Biopsy, Needle↗
PubMed1979

Clinical implications of gonadal venography in the management of the non-palpable undescended testis.

Selective gonadal venography was used on 28 patients with a total of 34 non-palpable undescended testes. The data obtained in this study suggest that 1) an internal spermatic vein with a pampiniform-like plexus indicates the presence of a testis, 2) a blind-ending vein on venography suggests the absence of a testis, 3) an internal spermatic vein or vas deferens may be present without a testis, 4) a testis probably cannot be present without a gonadal vein, 5) a testis may be present without a vas, 6) a blind-ending vas deferens does not necessarily indicate the absence of a testis and 7) a blind-ending vas deferens in a patient in whom a blind-ending gonadal vein is localized to the same region probably indicates the absence of a testis. Gonadal venography may localize a non-palpable undescended testis or suggest testicular agenesis. In addition, gonadal venography has aided in the selection of the operative approach and, in the future, may provide criteria under specific circumstances for determining whether an operation is necessary and, if so, the extent of surgical exploration.

Adolescent↗
PubMed1979

Obstruction induced changes in longitudinal force-length relations of rabbit ureter.

The force-length relationships of rabbit ureters subjected to 2 weeks of obstruction were compared with those of normal rabbit ureters. After 2 weeks of ureteral obstruction, length increased by 24 per cent, diameter by 100 per cent, and cross-sectional muscle area by 248 per cent. At the in vivo length, the resting forces of the control and obstructed ureters were similar. With muscle lengthening, resting force increased. For the same per cent increase over in vivo length, both control and obstructed ureters exhibited the same resting forces. At the in vivo length, the obstructed ureter developed less active force and less stress in response to a suprathreshold electrical stimulus than did control ureters. At the length of maximum force development (1.4 times the in vivo length for both control and obstructed ureters), the force developed by the obstructed ureter was 3.5 times greater than that of the control, yielding a 250 per cent increase over control levels. Thus, active stress (force/unit area) was unchanged after 2 weeks of obstruction.

Animals↗
PubMed1978

Uretral function.

Explore the source record for details and available documents.

Age Factors↗
PubMed1978

Clinical implications of gonadal venography in the management of the non-palpable undescended testis.

Selective gonadal venography was used on 28 patients with a total of 34 non-palpable undescended testes. The data obtained in this study suggest that 1) an internal spermatic vein with a pampiniform-like plexus indicates the presence of a testis, 2) a blind-ending vein on venography suggests the absence of a testis, 3) an internal spermatic vein or vas deferens may be present without a testis, 4) a testis probably cannot be present without a gonadal vein, 5) a testis may be present without a vas, 6) a blind-ending vas deferens does not necessarily indicate the absence of a testis and 7) a blind-ending vas deferens in a patient in whom a blind-ending gonadal vein is localized to the same region probably indicates the absence of a testis. Gonadal venography may localize a non-palpable undescended testis or suggest testicular agenesis. In addition, gonadal venography has aided in the selection of the operative approach and, in the future, may provide criteria under specific circumstances for determining whether an operation is necessary and, if so, the extent of surgical exploration.

Adolescent↗
PubMed1978

Adrenergic innervation of the ureter.

To determine whether the ureter is innervated by the autonomic nervous system, isolated canine ureters were superfused with modified Tyrode solution, and force developed in response to 100-msec duration stimuli at a rate of 3 per min was monitored. Norepinephrine and phenylephrine significantly increased developed force; the latter more than the former. These increases in developed force were blocked by phentolamine, and propranolol enhanced the stimulatory effect of norepinephrine. In the presence of phentolamine, norepinephrine significantly decreased developed force. Isoproterenol significantly decreased developed force and this significant decrease in contractility was not observed in the presence of propranolol. High intensity, high frequency, short duration stimuli which in themselves were unable to excite quiescent rabbit and canine ureteral segments potentiated contractile force of segments contracting at the basal rate of 3 per min in response to long duration stimuli. When these same high intensity, high frequency, short duration stimuli were applied to ureteral segments pretreated with phentolamine, the developed force of the basally driven preparations decreased. These data suggest the presence of alpha-stimulatory and beta-inhibitory adrenergic receptors in canine and rabbit ureter and provide evidence for adrenergic tissue within the wall of the ureter that can influence contractile force.

Animals↗
PubMed1977

Venographic localization of the non-palpable undescended testis in children.

In cases of bilateral non-palpable undescended testes in which human chorionic gonadotropin stimulation has shown the presence of testicular tissue and in cases of unilateral non-palpable undescended testes selective transfemoral gonadal venography with a modified Seldinger technique has been used for the preoperative localization of the non-palpable testis. since the undescended testis may be located anywhere along the course of its embryologic descent, that is from the level of the renal fossa to its exit from the inguinal canal, preoperative localization will aid in the surgical management. Gonadal venography has proved to be accurate and safe, and has aided in the determination of the extent of surgical exploration in 9 children with 12 non-palpable undescended testes (6 right and 6 left).

Abdomen↗
PubMed1977

Urethral closing pressure after spinal cord injury and its relationship to autonomic dysreflexia.

The evolution of patterns of neurogenic vesical dysfunction with emphasis on urethral resistance has been studied using a two-catheter urethral profile technique in 24 patients following acute spinal cord injury. Inappropriate urethral resistance to voiding appeared to result both from smooth and skeletal muscular activity and to some extent was dependent on the level of the spinal cord lesion. Autonomic dysreflexia was common, and responded to treatment with an alpha-sympatholytic agent.

Female↗
PubMed1977

Antibiotic treatment of renal carbuncle.

Renal carbuncles in seven young males were successfully treated with long-term administration of penicillinase-resistant antibiotics. Selective renal arteriography provided an accurate means of diagnosis and permitted a trial of medical therapy. All patients experienced a prompt and sustained clincial remission; surigical exploration was thus obviated in all but one instance, in which post-treatment radiographic changes persisted.

Adolescent↗
PubMed1977

Adenylate cyclase and phosphodiesterase activity in rabbit ureter.

Adenylate cyclase and phosphodiesterase enzyme activities were demonstrated in rabbit ureter. NaF, 10 mM, caused a 60.9 per cent increase in adenylate cyclase activity. Isoproterenol, 5 X 10-7 to 10-5 M induced a statistically significant dose-dependent increase in adenylate cyclase activity which was suppressed by propranolol, 10-7 M. Theophylline, 5 X 10-5 to 10-2 M, significantly inhibited phosphodiesterase activity. Thus, isoproterenol and theophylline, two agents that can relax ureteral segments previously contracted by a depolarizing concentration of potassium, could presumably increase cyclic AMP levels, isoproterenol by increasing synthesis and theophylline by decreasing degradation.

Adenylyl Cyclases↗