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Biomedical subjects

Ahmed Shafik

Publications and source records attributed to Ahmed Shafik.

At least 37 records · Page 2Linked to original sources
PubMed2006

The cavernoso-anal reflex: response of the anal sphincters to cavernosus muscles' stimulation.

AIM: To prove the hypothesis that cavernosus muscles' contraction during coitus affects the reflex contraction of anal sphincters. METHODS: Electromyographic response of external and internal anal sphincters to ischiocavernosus and bulbocavernosus muscle stimulation was studied in 17 healthy volunteers (10 men, 7 women, mean aged 38.3+/-11.6 years). The test was repeated after individual anesthetization of anal sphincters and the two cavernosus muscles, and after using saline instead of lidocaine. RESULTS: Upon stimulation of each of the two cavernosus muscles, external and internal anal sphincters recorded increased electromyographic activity. Anal sphincters did not respond to stimulation of the anesthetized cavernosus muscles nor did anesthetized anal sphincters respond to cavernosus muscles' stimulation. Saline infiltration did not affect anal sphincteric response to cavernosal muscles' stimulation. CONCLUSION: Cavernosus muscles' contraction is suggested to evoke anal sphincteric contraction, which seems to be a reflex and mediated through the "Cavernoso-anal reflex". Anal sphincteric contraction during coitus presumably acts to close the anal canal to thwart flatus or fecal leak.

Adult↗
PubMed2005

Interstitial cells of cajal in reflux esophagitis: role in the pathogenesis of the disease.

BACKGROUND: Interstitial cells of Cajal (ICCs) are claimed to be involved in gut electromotor activity. We investigated whether absent or diminished ICCs in the esophagogastric junction (EGJ) may be responsible for EGJ incompetence in gastro-esophageal reflux disease (GERD). MATERIAL/METHODS: Endoscopic specimens were obtained from the upper and mid third of the esophagus and from the EGJ of 29 patients (17 men, 12 women, mean age: 46.7 years) with GERD (5 grade A, 5 B, 6 C, and 13 D, Los Angeles classification) and from 8 controls. Sections were prepared for inmunohistochemical investigation using an ICC marker c-kit. Controls had normal rabbit serum substituted for the primary antiserum. RESULTS: C-kit-positive branched ICC-like cells were detected in the esophageal and EGJ musculature of the controls. They were distinguishable from the c-kit-negative unbranched smooth muscle cells and from the c-kit-positive unbranched mast cells. Immunoreactivity was absent in the negative controls. ICCs in the esophageal body existed in GERD and in controls, but were absent from the EGJ of 12 patients (2 grade C, 10 D) and occasionally detected in 5 of group A, 5 of B, 4 of C, and 3 of group D patients. CONCLUSIONS: ICCs were demonstrated in the esophageal body and EGJ of controls. In GERD patients they were detected in the esophageal body, but were deficient or absent in the EGJ. It is postulated that ICC absence or deficiency is responsible for EGJ incompetence and GER. The cause of ICC deficiency or absence needs to be investigated.

Adult↗
PubMed2005

Changes in the urine composition during its passage through the ureter. A concept of urothelial function.

Studies in our and other laboratories have negated the general assumption that the urothelium functions as a simple conduit and support the concept of a dynamic urothelium. Based on this concept, we investigated the hypothesis that urine undergoes changes during its passage in the ureter. Urine samples were separately collected from the renal pelvis and ureters of 23 volunteers (15 men, eight women, mean age 37.6 years) through cutaneous ureterostomy performed as a treatment for bladder cancer. The pH was determined using a pH electrode, osmolality by means of micro-osmometry and Na and K by flame photometry. The pH and osmolality of ureteric urine showed no significant differences from renal pelvic urine, whereas the Na and K levels of the ureteric urine were significantly increased (both P<0.05). Gender and age differences were not significant. Renal pelvic urine undergoes changes in Na and K concentrations during its passage through the ureter. These findings presumably indicate that the ureteral urothelium is a functioning epithelium and that the renal pelvic and ureteric urine are not identical.

Adult↗
PubMed2005

Oviductal motile response to penile cervical buffeting.

OBJECTIVES: We investigated the hypothesis that the oviduct exhibits increased motile activity during cervical buffeting. METHODS: The response of oviductal and uterine pressures to cervix uteri (CU) stimulation was recorded in 16 women (mean age 32.4+/-3.6 years) with normal menstrual history. Pressure measurements, performed by means of saline-perfused catheters introduced into each of the uterus and oviduct, were recorded upon both electrical and mechanical CU stimulation before and after CU anesthetization. RESULTS: CU stimulation produced a significant uterine pressure decrease with no significant difference between electrical and mechanical stimulation. Latency recorded mean of 17.6+/-1.2 ms for electrical stimulation and 17.2+/-1.2 for mechanical stimulation. CU stimulation caused also significant pressure rise in ampullary and isthmic parts of oviduct and a decrease of intramural oviduct with no significant difference between electrical and mechanical stimulation. Mean latency of electrical and mechanical response was 18.7+/-1.1 ms and 19.1+/-1.1 ms, respectively. Uterine and tubal pressure showed insignificant response to stimulation of the anesthetized CU. CONCLUSIONS: Cervical stimulation reduced uterine and intramural oviduct pressure and elevated pressure of ampullary and isthmic parts. These utero-tubal responses seem to be mediated through a reflex which we call "cervico-utero-tubal reflex" and to assist in sperm-ovum transport and fertilization.

Action Potentials↗
PubMed2005

Effect of warming on the rectal motile activity: identification of rectal warming reflex.

BACKGROUND: The identification in the rectal wall of warm receptors sensitive to warm temperature has not been found in the literature. Therefore, we investigated the hypothesis that rectal warming effects rectal dilation, which seems to indicate the existence of warm receptors. MATERIALS AND METHODS: The rectal wall tone was studied in 24 healthy volunteers (14 men, 10 women, mean age 36.7+/-10.4 years). It was assessed by a barostat system during rectal infusion with normal saline at 30 degrees C, 40 degrees C, 45 degrees C, and 50 degrees C. The test was repeated after rectal anesthetization with lidocaine. RESULTS: The rectal tone on rectal saline infusion at a temperature of 30 degrees C showed no response (P>0.05), whereas at a temperature of 40 degrees C, 45 degrees C, and 50 degrees C, it exhibited a significant decrease (P<0.05, <0.01, <0.001, respectively), which was proportional to the rising degree of temperature. Warm saline infusion into the anesthetized rectum resulted in no significant change in the rectal wall tone. CONCLUSIONS: Rectal infusion with warm saline produced rectal dilation that increased with temperature elevation. This effect is suggested to be mediated through a reflex called "rectal warming reflex: and advances the possibility of the existence of warm receptors in the rectal wall; however, further studies are needed to confirm the issue.

Adult↗
PubMed2005

The identification of specialized pacemaking cells in the anal sphincters.

BACKGROUND AND AIMS: Interstitial cells of Cajal (ICC) are claimed to generate the electrical activity in the colon and stomach. As the external (EAS) and internal (IAS) anal sphincters exhibit resting electrical activity, we hypothesized the presence of ICC in these sphincters. This hypothesis was investigated in the current study. PATIENTS/METHODS: Specimens from the EAS and IAS were taken from normal areas of the anorectum which had been surgically excised by abdominoperineal operation for rectal cancer of 28 patients (16 men, 12 women, mean age 42.2+/-4.8 years). The specimens were subjected to c-kit immunohistochemistry. Controls for the specificity of the antisera consisted of tissue incubation with normal rabbit serum substituted for the primary antiserum. RESULTS/FINDINGS: Fusiform, c-kit positive, ICC-like cells were detected in the anal sphincters; they had dendritic processes. They were clearly distinguishable from the non-branching, c-kit negative smooth and striated muscle cells of the anal sphincters. The specimens contained also c-kit positive mast cells, but they had a rounded body with no dendritic processes. Immunoreactivity was absent in negative controls in which the primary antibody was omitted. INTERPRETATION/CONCLUSION: We have identified, for the first time, cells in EAS and IAS with morphological and immunological phenotypes similar to ICCs of the gut. These cells appear to be responsible for initiating the slow waves recorded from the anal sphincters and for controlling their activity. A deficiency or absence of these cells may affect the anal motile activity. Studies are needed to explore the role of these cells in anal motility disorders.

Adult↗
PubMed2005

Identification of the location of the colonic pacemakers: a histologic study.

A recent electrophysiologic study has suggested the existence of 4 pacemakers in the colon which generate the electric waves that are responsible for the colonic motor activity. These pacemakers are located at the cecal pole, the cecocolonic junction, the mid third of the transverse colon and at the colosigmoid junction. We investigated the hypothesis that these pacemaker sites contain ICCs in great numbers and that the electric waves generated from these sites are transmitted by a chain of ICCs to the remaining colon. Specimens were taken from the 4 electrophysiologically defined pacemaker sites and the remaining colon of 24 cadavers. They were subjected to c-kit immunohistochemistry tests. Controls for antisera specificity consisted of tissue incubation with normal rabbit serum substituted for the primary antiserum. The morphometric study was performed by submitting the immunohistochemically-stained sections to image analysis in order to determine the area percent of immuno-reactivity in comparison to the total area of fields examined in the sections. Data obtained from the image analyzer were statistically analyzed. Immunohistochemical and morphometric studies have shown that the 4 electrophysiologically defined pacemaker sites contained a significantly higher proportion of ICCs than the remaining colon, the ICCs at these sites being multipolar and forming a network surrounded by a fibrous tissue wall. In the remaining colon, the ICCs were bipolar and arranged in a linear fashion. The study revealed the existence of a network of ICCs at the 4 pacemaker sites forming the 'pacemaker nodes' (PMNs). In the rest of the colon, a chain of ICCs extended in the colonic wall in a linear fashion forming the 'pacemaker bundles' (PMBs). We postulate that the colonic electric waves start at the PMNs and spread in the colon along the PMBs.

Animals↗
PubMed2005

Immunohistochemical identification of the pacemaker cajal cells in the normal human vagina.

OBJECTIVES: It is claimed that the electric waves recorded from the gut and urinary system are generated from specialized cells called interstitial cells of Cajal (ICCs). As the vagina exhibits electric activity, we investigated the hypothesis that ICCs could be detected in its wall. METHODS: Vaginal specimens were obtained from 28 female cadavers (mean age 34.8+/-10.8 SD years) and fixed sections were prepared for immunohistochemical investigations using the specific ICC marker c-kit. Controls for antisera specificity consisted of tissue incubated with normal rabbit serum substituted for the primary antiserum. RESULTS: Branching, c-kit-positive ICC-like cells were found in the muscular layer of the vagina. They were clearly distinguishable from the smooth muscle cells which were c-kit negative and not branched and from the c-kit positive non-branched mast cells. Immunoreactivity was absent in the negative controls. CONCLUSIONS: We have, for the first time, identified in the vagina ICCs that may be responsible for initiating the slow waves recorded from the vaginal smooth muscle cells.

Adult↗
PubMed2005

Effect of lower esophageal sphincter distension and acidification on esophageal pressure and electromyographic activity: the identification of the "sphinctero-esophageal excitatory reflex".

BACKGROUND: The mechanism of esophageal acid clearance through augmenting esophageal peristalsis in response to gastroesophageal reflux (GER) is not exactly known. We investigated the hypothesis that lower esophageal sphincter (LES) dilatation rather than the refluxed acid affected reflex increase in the esophageal peristaltic activity aiming at clearing the esophagus of the refluxed acid. METHODS: The esophageal pressure and electromyographic (EMG) activity response to esophageal sphincter balloon distension in increments of 2 mL of saline was recorded in 17 healthy volunteers (10 men, 7 women, mean age 43.6 +/- 11.2 years). The test was repeated in 10 of 17 volunteers while the esophageal sphincter was being anesthetized. The response of the esophageal pressure and electromyographic activity to lower esophageal acidification was also tested. RESULTS: Lower esophageal sphincter balloon distension with 2 mL of saline produced esophageal pressure increase to a mean of 34.2 +/- 5.3 cm H2O (p < 0.001). Increase of the balloon distending volume produced results similar to the 2-mL distension (p > 0.05). The esophageal electrical activity increased on esophageal balloon distension; the increase was similar with distensions of 2 mL up to 10 mL. There was no esophageal pressure or electrical activity response to distension of the anesthetized lower esophageal sphincter or to lower esophageal sphincter acidification. CONCLUSIONS: During gastroesophageal reflux episodes, the lower esophageal sphincter dilatation and not acidification appears to initiate increased esophageal peristalsis, which clears the esophagus of the refluxed acid. The increased esophageal peristalsis on lower esophageal sphincter dilatation is suggested to be reflex in nature and is mediated through the "sphincteroesophageal excitatory reflex." This reflex may be of diagnostic significance in esophageal motility disorders; however, this point needs further studies.

Adult↗
PubMed2005

On the pathogenesis of gastroesophageal reflux: the concept of gastroesophageal dyssynergia.

OBJECTIVES: The cause of lower esophageal sphincter incompetence in gastroesophageal reflux disease is not clearly understood. We investigated the hypothesis that the esophagogastric junction incompetence results from failure of the gastric distention to produce the lower esophageal sphincter and crural diaphragm contraction caused by a disordered reflex action. METHODS: The study was performed in 19 subjects (mean age, 42.6 +/- 7.2 years; 11 men and 8 women) who had reflux esophagitis and hiatus hernia and were scheduled for a fundoplication operation. Eight control volunteers (mean age, 41.8 +/- 6.9; 5 men and 3 women) who had huge supraumbilical ventral hernia but no reflux esophagitis or hiatus hernia were studied during operative hernia repair. The electromyographic activity and pressure response of the lower esophageal sphincter and crural diaphragm to separate esophageal and gastric distention were recorded. RESULTS: In the control subjects (volunteers) esophageal distention caused diminished electromyographic activity of the crural diaphragm and lower esophageal sphincter with decreased esophagogastric junction pressure, whereas gastric distention increased the electromyographic activity of the crural diaphragm and lower esophageal sphincter with increased esophagogastric junction pressure. In the patients the crural diaphragm and lower esophageal sphincter showed diminished resting electromyographic activity, with either no response or a paradoxical response to esophageal or gastric distention. CONCLUSION: The current study has demonstrated that the lower esophageal sphincter and crural diaphragm in patients with gastroesophageal reflux disease exhibited a diminished resting electric activity and either did not respond or reacted paradoxically to esophageal and gastric distention, constituting what we call esophagosphincteric and gastroesophageal paradox or dyssynergia. The cause of lower esophageal sphincter and crural diaphragm dysfunction is not known; a neurogenic cause was proposed. Further studies are required to investigate this point.

Adult↗
PubMed2005

Study of the rectal electric activity of the uninhibited rectal detrusor (overactive rectum): a new concept of pathogenesis.

BACKGROUND/OBJECTIVE: One of the causes of fecal incontinence is uninhibited rectal detrusor syndrome (URDS). Patients with this condition either perceived the first rectal sensation after the onset of involuntary rectal contraction or not at all. We investigated the hypothesis that the abnormal rectal contractility in URDS may be caused by deranged rectal electric activity. METHODS: Twenty-five patients with URD (14 women and 11 men; age, 44.7 +/- 10.3 years) and 10 healthy volunteers (6 women and 4 men; age, 42.8 +/- 8.7 years) were studied. URDS was diagnosed by rectometry and provocative test. A transcutaneous EMG was performed with one electrode placed lateral to each sacroiliac joint and the third one midway between the greater trochanter and the ischial tuberosity. Two 20-minute recording sessions were performed for each subject. RESULTS: Slow waves (SWs) with regular rhythm and similar parameters (frequency, amplitude, conduction velocity) from the 3 electrodes were recorded from the healthy volunteers. They showed a significant increase in the parameters on saline filling of the rectum. The SWs of patients with URDS exhibited a "dysrhythmic" pattern with irregular parameters, which were different in the 3 electrodes and inconsistent during recording. They showed areas of tachyrhythmia, bradyrhythmia, and arrhythmia. On provoking rectal overactivity, the SWs showed an increased dysrhythmic activity. CONCLUSIONS: The patients with URD exhibited a "dysrhythmic" electric pattern with areas of variable electric activity. The tachyrhythmic areas seem to initiate the urgency and fecal incontinence of URDS. It is suggested that a disordered rectosigmoid pacemaker causes the dysrhythmic waves.

Adult↗
PubMed2005

Effect of micturition on the external anal sphincter: identification of the urethro-anal reflex.

BACKGROUND/OBJECTIVE: A study on the response of the external anal sphincter (EAS) to the passage of urine through the urethra during micturition could not be found in the literature. We investigated the hypothesis that urine passage through the urethra effects EAS contraction to guard against possible flatus or stool leakage during micturition. METHODS: The study was performed in 23 healthy volunteers (age, 38.6 +/- 10.8 [SD] years; 14 men and 9 women). The EAS electromyogram (EMG) was performed during micturition by surface electrodes applied to the EAS. Also, the EAS EMG response to urethral stimulation by a catheter-mounted electrode was registered. The test was repeated after individual anesthetization of the EAS and urethra. RESULTS: The EAS EMG recorded a significant increase (P < 0.01) during micturition and on urethral stimulation at the bladder neck. Stimulation of the prostatic, membranous, or penile urethra produced no significant change in the EAS EMG. Urethral stimulation after individual EAS and urethral anesthetization did not cause any changes in the EAS EMG. CONCLUSIONS: Urine passing through the urethra or urethral stimulation at the vesical neck produced an increase in the EAS EMG, which presumably denotes EAS contraction, which seems to guard against flatus or fecal leakage during micturition. EAS contraction on urethral stimulation is suggested to be mediated through a urethro-anal reflex. Further studies on this issue may potentially prove the diagnostic significance of this reflex in micturition and defecation disorders.

Adult↗