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Biomedical subjects

S A Awad

Publications and source records attributed to S A Awad.

At least 37 records · Page 2Linked to original sources
PubMed1985

Effect of acute selective sacral rhizotomy in cats on bladder and urethral function and the response to bethanechol chloride.

Bladder and urethral responses to filling and to subcutaneous bethanechol are dependent upon intact sacral innervation. Acute selective sectioning of nerve roots in chloralose anesthetized cats was used to compare the sacral innervation requirements for the support of these responses. The detrusor was found to require primarily intact S2 roots although an S2 root on one side could, alone, subserve a weak, unsustained detrusor reflex. The urethral reaction to bladder filling required an afferent sacral pathway through either S1 or S2 roots. The sustained bladder response to subcutaneous bethanechol required greater sacral innervation than the detrusor reflex inasmuch as the S2 segment could subserve this response in only half the cases, and unilateral rhizotomy L7-S3 eliminated the response in half the cases. Both treatments, however, were compatible with a preserved detrusor reflex. The urethral constriction response to subcutaneous bethanechol required an intact sacral afferent pathway through either the S1 or S2 segments. In conclusion, the detrusor and urethral reflex responses to bladder filling and subcutaneous bethanechol require a certain amount of intact sacral innervation through S1 and S2 which is least for the detrusor reflex and greatest for the bladder response to subcutaneous bethanechol.

Animals↗
PubMed1985

Bladder and urethral function and supersensitivity to subcutaneously administered bethanechol in cats with chronic cauda equina lesions.

The failure of bethanechol chloride to induce voiding in patients with neurogenic bladder, despite a positive bethanechol test, is being reported more frequently. An experimental model was designed in the cat to study the response of the bladder and urethra to subcutaneous and intraarterial bethanechol after complete and partial sacral decentralization. Complete sacral rhizotomy abolished the micturition reflex. Basal urethral perfusion pressure was not affected by complete sacral rhizotomy and a significant part of this basal urethral pressure remained sympathetically mediated. However, the urethral constriction response to bladder filling was lost in half the cats with complete lesions. Bladder and urethral supersensitivity to bethanechol chloride in cats with complete lesions was characterized by a shift to the left of the i.a. dose-response curve, and by the presence of responses to doses of s.c. bethanechol chloride which are subthreshold in normal cats. The urethra also showed exaggerated constriction responses to i.a. and s.c. bethanechol. After complete lesions a part of the bladder and urethral responses to s.c. bethanechol was adrenergically mediated and exerted through the vesicourethral short neuron system. The rest of the response was due to stimulation of urethral muscarinic receptors. Partial sacral lesions were compatible with a micturition reflex and the urethra retained its reflex response to bladder distension. After partial decentralization the bladder and urethra also showed responses to subthreshold doses of s.c. bethanechol. While the bladder response to s.c. bethanechol did not show a significant adrenergic component in cats with partial lesions, most of the urethral response was sympathetically mediated. In conclusion, complete cauda equina lesions result in an areflexic detrusor with frequent loss of the urethral responsiveness to bladder filling. Urethral supersensitivity to s.c. bethanechol might be responsible for a non-voiding outcome after bethanechol injection in patients with complete cauda equina lesions, despite a positive bethanechol test. Because the detrusor reflex is preserved and the urethra is less supersensitive to bethanechol after partial cauda equina lesions, these may represent a better indication for bethanechol therapy than do complete ones.

Animals↗
PubMed1984

Experimental evidence for a central nervous system site of action in the effect of alpha-adrenergic blockers on the external urinary sphincter.

The present study was done to test the hypothesis that alpha-adrenoceptor blocking drugs (phentolamine and prazosin) could interfere with somatic control of the external sphincter through an action in the central nervous system. Stimulation of the hypogastric nerve in the chloralose-anesthetized cat caused a urethral constriction which could be antagonized by alpha-receptor blockers. However, the constriction produced by stimulation of the S1 or S2 ventral root was completely resistant to alpha blockade. The drugs therefore had the expected action against sympathetic stimulation of the urethra but had no peripheral effect on the somatic component. The central effect of these drugs was investigated by recording urethral perfusion pressure responses, or compound action potentials on the central cut end of the pudendal nerve, evoked by stimulation of the contralateral pudendal or pelvic nerve. The urethral constriction produced by stimulation of the central cut end of 1 pudendal nerve was antagonized by both prazosin and phentolamine. Action potentials evoked on the pudendal nerve by stimulation of the central cut end of the contralateral pudendal or pelvic nerve were substantially inhibited by prazosin. Phentolamine produced a more variable blockade of the pudendal-pudendal reflex. The results strongly indicate that these alpha-adrenoceptor antagonists and especially prazosin can influence pudendal nerve-dependent urethral responses through a central nervous system action and not through a peripheral mechanism.

Action Potentials↗
PubMed1984

Relationship between neurological and urological status in patients with multiple sclerosis.

The relationship between neurological urinary symptoms and urodynamic findings in patients with multiple sclerosis was examined. The duration of multiple sclerosis was significantly longer in patients with urinary symptoms. The presence of urinary symptoms correlated with the severity of the pyramidal or sensory lesions and the total disability score. Cystometrograms revealed detrusor hyperreflexia in 67 per cent of the patients, areflexia in 21 per cent and a normal detrusor in 12 per cent. Somatic dyssynergia was found in 20 of the 39 patients whose examination revealed clear-cut results. Positive correlation was found between urge incontinence and detrusor hyperreflexia, and between hesitancy and detrusor areflexia but no relationship was found between urological symptoms and sphincter function. Analysis of the neurological lesions in relation to the cystometric findings revealed a positive correlation among pyramidal lesions, detrusor hyperreflexia and detrusor areflexia, and between cerebellar lesions and detrusor areflexia. The correlation between detrusor dysfunction and high total disability score disappeared when patients with high pyramidal scores were excluded. No correlation could be detected between somatic dyssynergia and the various neurological lesions.

Adolescent↗
PubMed1984

Urethral response during bladder contraction induced by subcutaneous bethanechol chloride: elicitation of a sympathetic reflex urethral constriction.

The responses of the urethra to bladder filling and to subcutaneous bethanechol were studied in a surgically separated bladder-urethra preparation in chloralose anesthetized cats. With the pudendal nerves cut or the neuromuscular junction blocked with gallamine, urethral closure pressure increased during bladder filling and the initial phase of the micturition contraction. It then fell spontaneously or in response to bladder emptying through a vent. With the bladder volume held constant subcutaneous bethanechol induced an increase in basal bladder pressure which culminated in a sustained (reflex) contraction. The urethral constrictor response resembled that seen during the cystometrogram; an increase during the rise in detrusor pressure and a fall during the latter part of the sustained (reflex) contraction. In both cases the urethral response was substantially depressed by hypogastric nerve transection or by intravenous prazosin, implying that the urethral responses were reflexly mediated through the sympathetic system. Intra-arterial bethanechol also produced a urethral constriction, but this response was abolished by atropine and not affected by hypogastric nerve section or prazosin. It is therefore concluded that although bethanechol can produce urethral constriction through a direct muscarinic action on the urethra, it does not do so after subcutaneous administration in a neurally intact cat. The urethral response seen after subcutaneous bethanechol administration is part of the micturition reflex complex and is sympathetically mediated.

Animals↗
PubMed1983

Factors that influence the incidence of detrusor instability in women.

Detrusor instability was examined in 108 women with urinary incontinence. The presence of instability correlated with the symptoms of urge incontinence in 81 of 99 patients. The technique of the cystometrogram also proved important and minor variations significantly altered the incidence. Finally, there seems to be a significant correlation between reduced urethral closure as measured by the urethral pressure profile and instability, suggestive of a causal relationship. An understanding of the factors that affect the incidence of detrusor instability will help to place it in the right perspective in terms of its diagnostic value and pathogenesis.

Female↗
PubMed1982

Behavioural treatment of urinary incontinence in geriatric patients.

Urinary incontinence and a program to treat it were studied in a geriatric hospital. Of 161 men, 58 (36%) were incontinent. The most common probable causes were cerebrovascular accident and organic brain syndrome. Evaluation by cystometry (after treatment of infections) in 30 patients showed 24 (80%) to have detrusor hyperreflexia. Twenty patients with hyperreflexia completed a timed-voiding routine, which benefited 17 of them (85%).

Aged↗
PubMed1982

Acute renal failure secondary to bilateral ureteric obstruction: review of 50 cases.

The records of 50 patients with acute renal failure secondary to bilateral ureteric obstruction were reviewed. An underlying malignant disorder was the cause of the obstruction in 38 of the patients and had not previously been diagnosed in almost half of them. Carcinomas of the cervix and prostate were the most frequent malignant disorders, and aggressive management resulted in good survival rates. Similarly, the outcome for patients with benign bilateral ureteric obstruction, usually caused by retroperitoneal fibrosis, was good with proper management.

Acute Kidney Injury↗
PubMed1982

Dysfunction of the detrusor and urethra in multiple sclerosis: the role of drug therapy.

Urinary tract disorders secondary to multiple sclerosis are common. In this series of 24 patients with multiple sclerosis, 5 had normal function of the detrusor, 3 had detrusor hypotonicity and 16 had detrusor hyperreflexia. The proximal urethra was evaluated using radiologic and electromyographic techniques. These studies showed that 5 patients had a normal urethra, 15 had some degree of somatic dyssynergia and 3 had sympathetic dyssynergia. Detrusor hyperreflexia with somatic dyssynergia was found in 11 patients and was the most common pattern. The therapeutic response to standard pharmacologic preparations was also evaluated. The regimen was based on the clinical and urodynamic findings for each patient. Dicyclomine hydrochloride was the drug of choice for detrusor hyperreflexia, bethanechol chloride for hypotonicity, dantrolene sodium for somatic dyssynergia and phenoxybenzamine hydrochloride for sympathetic dyssynergia. The authors found that most of their patients were amenable to drug therapy, the exception being those with advanced neurologic lesions.

Adult↗
PubMed1981

The continence mechanisms: the effect of bladder filling on the urethra.

We developed a surgical model in the cat, in which the bladder was completely separated from the urethra, in order to examine the changes in urethral resistance during bladder filling. An increase in urethral resistance occurred in two phases: an "initial" increase attributable to the activity of both the striated sphincter and the sympathetically innervated smooth muscle, and a "late" increase that is alpha-sympathetically mediated. The latter was secondary to trigonal distension. We concluded that the increased urethral activity during bladder filling is reflexly mediated and that the trigone plays a role in its control.

Animals↗
PubMed1980

Skin flap technique in formation of urinary conduit stoma.

Stomal stenosis following ileal loop diversion is a significant complication to warrant attention. One of the predisposing factors remains the circular nature of the stoma itself, often in conjunction with chronic skin irritation. Surgical revisions predispose one not only to the usual hazards of operation, but also tend to be multiple or involve extensive surgical reconstruction. A skin flap technique in the initial formation of the stoma avoids the incidence of stenosis related to the circular nature of the stoma. The procedure is simple and does not increase the surgical time. No significant stomal complications developed in 28 patients who had urinary diversions, followed for a mean of 30.6 months.

Adolescent↗
PubMed1980

Response of the bladder to bethanechol after acute spinal cord transection in cats.

Immediately after spinal cord transection, normal bladder reflex activity is lost and voiding contractions in response to cholinergic drugs can no longer be elicited. Intravesical pressure responses to s.c. and i.a. bethanechol were studied in male cats before and after spinal cord transection at T6 to T7. Bethanechol s.c. enhanced spontaneous bladder activity and produced a sustained bladder contraction. The sustained response was abolished by spinal transection. The response of the bladder to i.a. bethanechol consisted of two phases. The first, dose-related phase, which resembled the response to i.a. acetylcholine, was unchanged by spinal cord transection, rhizotomy (L7-S3) or by ganglion blockade with hexamethonium. The second sustained phase, like the s.c. response, was markedly reduced by all three treatments. Because the response to bethanechol in vitro did not differ in control and transected preparations, it is unlikely that the depressant effects are due to a persistent change in bladder muscle responsiveness. No contractions were observed regardless of s.c. injection site; hence, altered drug absorption and distribution are not sufficient to explain the diminished responses observed. Because interruption of pelvic parasympathetic reflex pathways by rhizotomy and ganglion blockade interfered with the responses to s.c. and i.a. bethanechol, we conclude that bethanechol requires intact pelvic reflex pathways in order to produce sustained contractions. The prolonged action of bethanechol is an important feature contributing to its effectiveness. Removal of reflex functions by spinal cord transection might explain the ineffectiveness of cholinergic drugs in both patients and experimental animals in the acute, areflexic stage after spinal cord transection.

Acetylcholine↗
PubMed1979

Pharmacologic treatment of disorders of bladder and urethra: a review.

The use of pharmacologic agents in treating disorders of the bladder and proximal urethra has expanded because of new knowledge gained in the past few years. A better understanding of the properties of these organs as they relate to drugs has contributed to this expansion. The authors present their experience with a number of drugs in treating disorders of the detrusor muscle and proximal urethra, and they briefly review the literature.

Adrenergic alpha-Agonists↗
PubMed1979

The state of urethral musculature during the detrusor areflexia after spinal cord transection.

The state of the urethral musculature was studied using the urethral pressure profile and electromyographic recording in periurethral striated muscle. In dogs under chloralose anesthesia a micturition reflex could be elicited by bladder distension and somatic reflexes could be elicited by various stimuli. Both the urethral profile and electromyographic activity could be recorded immediately after surgical transection of the spinal cord between T2 and T8 but the bladder remained areflexic for more than 12 hr. Pharmacologic analysis of the urethral pressure profile revealed a substantial contribution from both sympathetic and somatic components. The periurethral striated musculature usually responded to bladder filling in a similar manner both before and after transection, although there was no bladder contraction in the latter circumstance. It is concluded that the urethra does not experience the same depression of reflex activity as does the bladder in the acute stage after spinal cord transection.

Animals↗
PubMed1978

Urethral pressure profile in female stress incontinence.

The accuracy of the urethral pressure profile as a measure of sphincteric competence was examined in female subjects. Most profile measurements selected proved to be significantly different in patients with stress incontinence from those in controls. However, the measurement that seemed to have the highest potential for diagnostic accuracy was the maximum closure pressure in the continence zone, recorded with the bladder full and the patient standing. The concept of the continence zone and incorporating the effect of standing were believed to be the main reasons for this high accuracy. The second best measurement was the maximum closure pressure with the bladder full and the patient surpine. To lessen the chances of a diagnostic error it was recommended that both of these measurements should be obtained. The physiological implications of these findings and the clinical role of the urethral pressure profile examination in the assessment of female patients with urinary incontinence are discussed.

Adult↗