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Biomedical subjects

R M Weiss

Publications and source records attributed to R M Weiss.

At least 127 records · Page 7Linked to original sources
PubMed1987

Usefulness of residual ischemic myocardium within prior infarct zone for identifying patients at high risk late after acute myocardial infarction.

This study examines the prognostic implications of ischemia within the territory of a prior acute myocardial infarction (AMI) vs ischemia at a distance, which develops late after AMI. Sixty-one consecutive patients who underwent both exercise thallium-201 (TI-201) imaging and cardiac catheterization for evaluation of chest pain that developed after discharge from the hospital for AMI form the study group. Mean interval between infarction to the TI-201 study was 10 +/- 17 months. Initial and 2-hour delay TI-201 images were analyzed quantitatively to determine the presence and location (within vs outside the prior infarct zone) of TI-201 redistribution, a marker of ischemic viable myocardium. TI-201 imaging results were separated into 3 groups based on presence and location of TI-201 redistribution: no significant TI-201 redistribution was found in 16 patients; in 29, TI-201 redistribution was confined to the infarct zone; and in 16, TI-201 redistribution was outside the infarct zone. Stepwise multivariate logistic regression analysis was used to examine the comparative ability of TI-201 results and other patient variables to predict cardiac events. For total cardiac events (cardiac death, recurrent nonfatal AMI, unstable angina and coronary revascularization), both the presence of any TI-201 redistribution and multivessel angiographic coronary artery disease were significant predictors. However, when coronary revascularization was excluded as an endpoint, TI-201 redistribution limited to the prior infarct zone was the only significant predictor of cardiac events. All 8 cardiac events occurred in patients with T1-201 redistribution limited to the infart zone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Laparoscopy in the management of the nonpalpable testis.

Laparoscopy was performed at operation in 32 patients between 7 and 63 months old (average age 31 months), who had 33 nonpalpable testes. Of the testes 7 (21.2 per cent) were in the inguinal region or just proximal to the internal ring, 5 (15.2 per cent) were in a high intra-abdominal position and 21 (63.6 per cent) were absent. In every instance of a nonpalpable gonad in which a testis was found to be absent at operation the vas and gonadal vessels were observed laparoscopically to exit the inguinal ring or to end blindly just proximal to the internal inguinal ring. A hernia or patent processus vaginalis was not observed in these 21 cases. In every case of an absent testis the contralateral testis was located normally in the scrotum. Furthermore, when a hernia was observed laparoscopically a testis was found on the ipsilateral side at the level of the internal ring or more distally.

Abdomen↗
PubMed1987

Ureteral urine transport: changes in bolus volume, peristaltic frequency, intraluminal pressure and volume of flow resulting from autonomic drugs.

An experimental model which permits independent changes in ureteral peristalic frequency and bolus volume was employed to explore the effects of autonomic agonists on ureteral bolus volume, peristaltic frequency, intraluminal pressure and flow volume in the dog. Norepinephrine caused an increase in ureteral peristaltic frequency, an elevation in intraureteral baseline and contractile pressure and a decrease in bolus volume, with a resultant decrease in the rate of fluid transport. Isoproterenol caused a decrease in ureteral peristaltic frequency, and a fall in intraureteral baseline and contractile pressure, or it completely abolished peristalsis and bolus formation. These changes were accompanied by an increase in the rate of fluid transport. Acetylcholine caused an increase in ureteral peristaltic frequency, an elevation of intraureteral baseline pressure but no change in contractile pressure, and a small decrease in bolus volume with a resultant small decrease in the rate of fluid transport. These data suggest that the autonomic nervous system may affect urine transport through the ureter by not only regulating peristaltic frequency but also by influencing bolus volume.

Acetylcholine↗
PubMed1987

Complications of ureteral endoscopy.

Use of the rigid ureterorenoscope has become widely accepted for the diagnosis of ureteral lesions, and for the removal and disintegration of ureteral calculi. Few complications have been reported. During the last 3 years 128 ureteroscopic procedures were performed for a variety of indications (98 for stone disease). There were 26 complications: 22 minor with no morbidity and 4 major that required surgical correction. Minor complications consisted of asymptomatic ureteral perforations in 6 patients, perforations with urinary extravasation, pain, ileus or fever in 4, migration of the stone into the kidney in 10 and migration of the stone outside the ureter with the calculus left in situ in 2. Major complications included ureteral perforation during basket extraction of an upper ureteral stone, urinoma following perforation and requiring drainage, stenosis of the intramural ureter that was corrected by marsupialization and aseptic necrosis of the ureter that was treated by ileal replacement.

Aged↗
PubMed1987

Sex differences in function and distribution of alpha 1- and alpha 2-adrenoceptors in rabbit urethra.

To define the functional role of postsynaptic alpha-adrenoceptors in urethral smooth muscle, we examined the effects of various alpha-adrenergic agonists and antagonists on the contractile properties of the isolated urethra of male and female rabbits and quantified the population of alpha 1-and alpha 2-adrenoceptors, using radioligand receptor binding techniques. Norepinephrine (NE), epinephrine, and phenylephrine, an alpha 1-adrenergic agonist, induced increases in contractile force in both the male and female urethra. Clonidine, an alpha 2-adrenergic agonist, caused a relatively large contractile response in the female urethra but only a small contractile response in the male urethra. Receptor binding studies indicated that the male urethra contains almost equal amounts of alpha 1- and alpha 2-adrenoceptors (32 vs. 34 fmol/mg, respectively), whereas the female urethra contains a significantly greater density of alpha 2- than alpha 1-adrenoceptors (122 vs. 34 fmol/mg, respectively). Our studies indicate that both alpha 1- and alpha 2-adrenoceptors cause contractile responses in male and female rabbit urethra; and the greater response to alpha 2-agonist in female than male urethra is correlated with a higher density of alpha 2-adrenoceptors in this tissue.

Animals↗
PubMed1987

Age-related changes in contractile force of rabbit detrusor muscle to prostaglandin E1, E2 and F2 alpha.

Contractile responses of urinary bladder muscle strips to prostaglandin (PG) E1, E2 and F2 alpha were compared in young and old rabbits. All PGs tested caused an increase in contractile force of urinary bladder muscle strips from young (3 weeks) and old (greater than 2 years) rabbits. The contractile response was most marked with PGE2 at concentrations of 10(-10)-10(-7) M in muscle strips from both young and old rabbits. At a high concentration (10(-5) M), the contractile response was most marked with PGF2 alpha in young rabbit bladder muscle strips, whereas in old rabbit bladder muscle strips the magnitude of the responses to PGE2 and PGF2 alpha were equal at 10(-6) M and both were greater than the response to PGE1. The contractile response to PGE1 was greater in old detrusor than in young detrusor at concentrations greater than or equal to 10(-6) M, whereas the contractile response to PGE2 (10(-7)-10(-5) M) and PGF2 alpha (10(-6)-10(-5) M) were greater in young detrusor than in old detrusor. These data show that rabbit detrusor muscle shows a contractile response to PGE1, E2 and F2 alpha and that the magnitude of these responses vary with age.

Aging↗
PubMed1986

Acute adrenal insufficiency as a complication of urological surgery.

Acute adrenal insufficiency postoperatively is an uncommon problem and, if unrecognized, it may cause serious morbidity and can be fatal. It can occur as the result of acute bilateral adrenal hemorrhage associated with anticoagulation, inadvertent injury to or removal of a solitary adrenal gland, or postoperative stress in an individual with incipient adrenal insufficiency. Its manifestations, such as fever, tachycardia, hypotension, lethargy, abdominal pain and gastrointestinal dysfunction, mimic the other more common postoperative complications and compound the difficulty in establishing the correct diagnosis. Once the diagnosis is made the condition is readily managed successfully. We report 3 cases of acute adrenal insufficiency occurring after salvage cystectomy, ileal replacement of the ureter and retropubic prostatectomy, which illustrate the salient clinical features, problems in diagnosis and predisposing risk factors. All 3 patients survived once the diagnosis of adrenal insufficiency was made. These cases emphasize the need to be aware of the possibility of this complication to make the correct diagnosis and to institute proper treatment.

Adenocarcinoma↗
PubMed1986

High resolution real-time ultrasonography in the localization of the undescended testis.

In a prospective study ultrasound was compared to palpation in 41 instances in which a testis was not present in the scrotum. A testis was palpable in 20 of these instances and not palpated in 21. Of 20 palpable undescended testes 14 (70 per cent) were identified by ultrasound. Of the 21 instances in which a testis was not palpated 3 intra-abdominal and 5 inguinal testes were identified at exploration. One of these organs (an inguinal testis) was identified by ultrasound. Two false positive sonograms in which a gubernacular structure mimicked an undescended testis occurred. Sonography cannot satisfactorily stand alone as a screening modality in the management of the undescended testis.

Abdomen↗
PubMed1986

Relaxant effect of forskolin in rabbit detrusor smooth muscle: role of cyclic AMP.

Forskolin caused a concentration dependent relaxation of rabbit detrusor muscle strips. The relaxant effect of forskolin was potentiated by the cyclic AMP sensitive phosphodiesterase inhibitor, Ro20-1274. Pretreatment with the beta-adrenergic antagonist, propranolol, did not inhibit the relaxation of rabbit detrusor induced by forskolin, whereas the relaxation response to forskolin was inhibited in part by the adenylate cyclase inhibitor, SQ22536. Forskolin also increased cyclic AMP levels significantly in rabbit detrusor muscle. These data suggest that detrusor muscle relaxation by forskolin may be mediated by cyclic AMP and that forskolin may activate adenylate cyclase without stimulating beta-adrenergic receptors in detrusor muscle.

Adenine↗
PubMed1986

Effects of noradrenaline, isoproterenol and acetylcholine on ureteral resistance.

Resistance to fluid flow in the canine ureter can be divided into two categories. The higher resistance is recorded at flow rates less than or equal to 2.16 ml./min. At these rates the ureter is able to completely coapt its walls so that urine is transported in individual boluses. The lower resistance is recorded at flow rates greater than or equal to 5.40 ml./min. At these rates the ureteral walls remained open and urine is transported as a column of fluid. Noradrenaline causes a marked increase in ureteral resistance at low flow rates and a small but statistically significant increase in ureteral resistance at high flow rates. Acetylcholine increases resistance only at the low flow rates. Isoproterenol significantly decreases resistance at both low and high flow rates. These findings are consistent with ureteral resistance to fluid flow being composed of two components. One is the ureteral peristaltic contraction which plays a principal role in urinary bolus transport at low flows; the other is ureteral wall tonus, which plays an important role in the transport of columns of urine by the ureter, which does not coapt its walls, at the higher flow rates.

Acetylcholine↗
PubMed1986

Effect of dibutyryl cyclic adenosine monophosphate on canine pelviureteral discharge potentials.

An electromyographic study of the responses of the pelviureter to dibutyryl cyclic AMP was performed using isolated canine pelviureteral preparations. Dibutyryl cyclic AMP caused a marked increase in the amplitude of discharge potential in the pelvicalyceal pacemaker region and this was associated with a decrease in renal pelvic pressure. The frequency of the pacemaker discharge did not increase. On the other hand, in the lower pelvis and ureter, dibutyryl cyclic AMP caused a small but significant decrease in the amplitude of discharge potentials and this was associated with a marked decrease in discharge frequencies in the lower pelvis and ureter.

Animals↗
PubMed1986

Sphincteric action of the pelvicalyceal junction and pacemaker activity in human kidney.

The effect of elevation of renal pelvic pressure on pacemaker activity was examined in 5 isolated human kidneys. Pressure fluctuations transmitted from renal pelvic contractions first appeared in pressure tracings from the upper renal calyx as renal pelvic pressure exceeded 25 cm H2O. This finding suggests that the pelvicalyceal junction acts as a sphincter which can withstand pelvic pressures of about 25 cm H2O. The upper renal calyx contracted rhythmically at a rate of 10 times per minute when the pelvic pressure was low. At high pelvic pressures, upper calyceal contraction frequency decreased although its rhythm remained regular. As renal pelvic pressure increased, the frequency of renal pelvic contractions increased to a level that corresponded in a 1:1 ratio with contractions of the upper calyx.

Humans↗
PubMed1986

The role of ureteral peristaltic rate and bolus volume on increasing urine flow.

Electromyogram (EMG) and bolus volume of ureteral peristalsis were measured during gradual and rapid urinary flow increase in mongrel dogs. In acute diuresis induced by furosemide, the ureteral peristaltic rate rose and then the bolus volume increased with a consequent increase of urine flow. During a course of gradually increasing urine secretion, the ureter showed varying responses in respect to peristaltic rate (i.e., increase, no change and decrease) but changes in the bolus volume consistently made up for the rate alterations, thereby eventually maintaining an efficient equilibrium of these two urodynamic parameters to effect an increase in urine flow. The ureteral peristaltic rate increases only several times in polyuria as compared to the rate in oliguria, whereas the bolus volume of urine increases by a factor of 100. This indicates that it is not so much the ureteral peristaltic rate as the bolus volume which plays a principal part in the transport of urine through the ureter.

Animals↗
PubMed1986

Patient positioning and nasal intubation for carotid endarterectomy.

Exposure of a very rostral carotid bifurcation for endarterectomy may occasionally be difficult. We are reporting a simple yet effective way to gain several centimetres of exposure of the distal cervical portion of the internal carotid artery in this circumstance.

Carotid Arteries↗