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Biomedical subjects

Ahmed Shafik

Publications and source records attributed to Ahmed Shafik.

At least 55 records · Page 3Linked to original sources
PubMed2005

Specialized pacemaking cells in the human Fallopian tube.

It is postulated that the propagated electric activity of the gut is generated by the interstitial cells of Cajal (ICCs). We investigated the hypothesis of the presence of ICCs in the Fallopian tube (FT) as initiators of the tubal electric activity. Specimens from various parts of the FT were obtained from 21 female cadavers (mean age 38.2 +/-10.9 years) from the PostMortem Department of the Cairo University, Faculty of Medicine. Fixed sections were prepared and stained for c-kit. Controls for antisera specificity consisted of tissue incubated with normal rabbit serum substituted for the primary antiserum. Dendritic, c-kit-positive, ICC-like cells were detected in the tubal musculature of the studied specimens. They were distinguishable from the c-kit-positive nonbranching mast cells and from the c-kit-negative smooth muscle cells (SMC). Immunoreactivity was absent in the negative controls. We have for the first time identified cells in the FT with morphologic and immunologic phenotypes similar to the ICCs of the gut. These cells may be responsible for initiating the slow waves (SWs) recorded from the SMC of the FT. This is a preliminary study, and further studies are needed to investigate the functional role of these cells.

Action Potentials↗
PubMed2005

Transcutaneous electrocavernosography: a tool for recording the electromyographic activity of the corpora cavernosa.

PURPOSE: The electric activity of the corpora cavernosa (CC) is recorded by needle electrodes introduced into the CC. We investigated the hypothesis that transcutaneous electrocavernosography (ECG) would register electric waves similar to those recorded by the needle ECG but noninvasively. MATERIALS AND METHODS: The ECG was recorded transcutaneously in 35 healthy volunteers (mean age 37.6 +/- 4.8 SD years). Two silver-silver chloride electrodes were applied on the dorsum of the penis over 1 of the CC. A reference electrode was applied to the thigh. Intracavernosal ECG using 2 needle electrodes introduced into the CC was performed in the same subjects. At least two 20 minutes sessions were recorded for each subject. RESULTS: Slow waves (SWs) were registered transcutaneously. The waves from the 2 electrodes in each individual had the same frequency, amplitude and conduction velocity. They had a regular rhythm and were reproducible. The SWs were followed or superimposed by action potentials which occurred randomly. The transcutaneously recorded SWs were confirmed by the intracavernous route. Both routes had similar ECG recordings. CONCLUSIONS: The study demonstrated that the transcutaneous ECG recorded electric waves similar to those registered by the intracavernosal route. The transcutaneous ECG is simple, easy, non-invasive, and may be included as an investigative tool in the diagnosis of erectile dysfunction.

Action Potentials↗
PubMed2005

Effect of vaginal distension on anorectal function: identification of the vagino-anorectal reflex.

BACKGROUND: Sexual stimulation produces not only reflex changes in the female external and internal reproductive organs but also extragenital reactions. A mention of the response of the anal sphincters and the rectum to penile thrusting could not be traced in the literature. We investigated the hypothesis that the anal sphincters and the rectum respond to penile thrusting in a way that prevents gas and fecal leakage during sexual intercourse. METHODS: The response of the external anal sphincter (EAS) and the internal anal sphincter (IAS) and the rectum to vaginal balloon (condom) distension was recorded in 23 healthy women (age: 33.7 +/- 7.3 years). The vaginal condom was inflated with air in increments of 50-300 ml, and the electromyographic (EMG) activity of the EAS and the IAS, as well as rectal pressure, was recorded. The test was repeated after separate anesthetization of the vagina, the rectum, the EAS and the IAS and after the use of normal saline instead of lidocaine. RESULTS: Vaginal distension reduced the rectal pressure in the ratio of expansion of the vaginal volume up to a certain volume, beyond which the rectal pressure ceased to decline when more distending volume was added. Similarly, the internal sphincter EMG activity increased progressively on incremental vaginal distension increase until the 150-ml distension was reached after which more vaginal distension caused no further increase of the EMG activity; external sphincter EMG activity showed no response. Vaginal distension, while the vagina, the rectum, the EAS, and the IAS had been separately anesthetized, produced no significant change, but saline did. CONCLUSIONS: Vaginal balloon distension appears to effect rectal wall relaxation and increase of the internal sphincter tone. This seems to provide a mechanism to avoid rectal contents leakage during coitus. Rectal and internal sphincter response to vaginal distension is suggested to be mediated through a reflex we term 'vagino-anorectal reflex', which seems to be evoked by vaginal distension during penile thrusting. The reflex may prove of diagnostic significance in sexual disorders; further studies are needed in order to investigate this point.

Adult↗
PubMed2005

Electric waves recorded from the testicle: are they capsular or from the testicular tissue?

We demonstrated in a previous study that electric waves could be recorded from the testicle by applying the electrodes either directly to the tunica albuginea (TA) or transcutaneously. As the TA contains smooth muscle fibres which presumably transmit the electric waves, we investigated the hypothesis that the electric waves recorded from the testicle originated from the TA. During the repair of inguino-scrotal hernia in 24 men [age 36.6 +/- 8.6 years (mean +/- SD)], the tunica vaginalis was everted because of the presence of hydrocele. The electric activity of the TA was recorded by three surface electrodes and that of the testicle by three needle electrodes. The recorded potentials were amplified and displayed on an electromyographic apparatus. Triphasic slow waves (SWs) were recorded from the TA. They showed similar frequency, amplitude and conduction velocity from the three electrodes of the individual subject and were reproducible. They were followed or superimposed by bursts of action potentials (APs) which occurred randomly. No waves were recorded from the three needle electrodes inserted into the testicular tissue. The current study could demonstrate that the electric waves recorded from the electrodes applied to the testicle were derived from the TA and not from the testicular tissue. This finding apparently denotes that the TA has a resting tone and probably motile activity, the role of which in testicular function needs to be studied.

Action Potentials↗
PubMed2005

Effect of topical esophageal acidification on salivary secretion: identification of the mechanism of action.

BACKGROUND: In past studies, investigators have reported that the salivary glands respond to esophageal acidification by increased salivary secretion and termed this response the 'esophago-salivary response'. The existence, however, of such a reflex was but a speculation because the verification of its mechanism could not be traced in the literature. In the current study, the hypothesis that the salivary glands' response to esophageal acidification is a reflex was investigated. METHODS: In 15 healthy volunteers (nine men, six women, age 32.3 +/- 4.2 years) the saliva of the four salivary glands was collected by intubation after individual esophageal perfusion with normal saline and 100 mmol HCl. The test was repeated after each of the lower esophagus and the salivary glands had been separately anesthetized. The latency was calculated. RESULTS: The mean basal volume of saliva was 62.7 +/- 6.4 mL/60 min. This volume did not show a significant change (P > 0.05) on esophageal saline instillation, whereas acid perfusion effected a significant increase (P < 0.01). The mean latency was 12.4 +/- 2.7 s. Esophageal acid perfusion after lower esophageal anesthetization did not produce a significant change in salivary volume; similar results were obtained on repetition of the test after anesthetization of salivary glands. When saline was used instead of lidocaine in the lower esophagus or salivary glands, the salivary glands' response was similar to that without saline perfusion. CONCLUSION: Esophageal acidification effected an increase of secreted saliva which clears the esophagus of the refluxed acid. Increased salivation on esophageal acidification is suggested to be a reflex and is mediated through the 'esophago-salivary' reflex. This reflex might be of diagnostic significance in the investigation of reflux esophagitis, a point that requires further study.

Adult↗
PubMed2005

Surgical anatomy of the perineal muscles and their role in perineal disorders.

The anterior perineum contains the perineal body and muscles. It is the site of functional and pathological disorders, many of which have not yet been related to a precise cause. In the present study, we investigated the anatomy of the perineal muscles with the aim of elucidating their function in light of their anatomic structure. Knowledge of their functional-structural relationship is deemed necessary for the understanding of the disorders that affect this part of the perineum. The perineal muscles of 28 cadaveric specimens were studied by direct dissection, as well as histologically. Fifteen male and 13 female specimens were collected from 18 adult (mean (+/- SD) age 31.6 +/- 9.8 years) and 10 neonate cadavers. Histological sections were stained with hematoxylin and eosin and Masson's trichrome stain. The fibers of the superficial transverse perineal muscle proceeded medially to decussate in a criss-cross pattern with the muscle fibers of the contralateral muscle; a few muscle fibers passed directly without decussation. Similarly, the fibers of the deep transverse perineal muscle decussated with their fellows on the opposite side. The two decussation raphes constituted the main bulk of the perineal body. A 'digastric' pattern could be identified for each of the superficial transverse perineal muscle and deep transverse perineal muscle. This pattern allows simultaneous contraction of the muscles on both sides as a single unit. The perineal muscles, forming the floor of the anterior perineum, are apparently subjected to variations in intra-abdominal pressure, which, if exceeding normal physiological limits, may lead to weakening, subluxation and sagging of the perineal muscles and, eventually, to perineocele. Further studies to investigate the role of the perineal muscles in the functional disorders of the perineum are needed.

Adolescent↗
PubMed2005

Electric activity of the testicular tunica albuginea during ejaculation: a canine study.

We have shown in previous studies that electric waves at rest could be recorded from the testicle and originate from the tunica albuginea (TA) and not from the testicular tissue. In the current study, we investigated the hypothesis that the electric activity of the TA increases during ejaculation. Three electrodes were sutured to the TAs of 11 anesthetized male dogs. The slow waves were recorded at rest and on inducing ejaculation by an ejaculator applied to the glans penis. Basal electric waves were recorded from the testicle. Each wave consisted of a negative followed by a positive deflection with a mean frequency of 6.2 +/- 1.3 cycles/min, an amplitude of 0.59 +/- 0.06 mV, and a conduction velocity of 5.2 +/- 0.8 cm/sec. These wave variables showed a significant intermittent increase (P < 0.05) at intervals of 0.6-1.0 secs and occurred simultaneously with the bouts of ejaculation. The increase remained for 0.8-1.2 secs at each ejaculation bout. The number of bouts of increased electric waves varied from 3 to 5. Apparently, the TA is not an inert covering to the testicle, but it seems to have a functional activity. Recording resting electric waves of the TA presumably denotes that the TA possesses a resting tone that appears to support the testicular tissue. During ejaculation, the increased electric activity of the TA, which coincides with semen spurt episodes, presumably denotes TA contraction. The intermittent TA contractions seem to assist in massaging the testicular secretions to the epididymis and the vas deferens and augment testicular circulation. The effect of pathologic conditions of the TA on ejaculation needs to be studied.

Animals↗
PubMed2005

Uterine effect of cervical buffeting: role of the cervicouterine reflex in coitus.

OBJECTIVE: To investigate the hypothesis that cervical buffeting during coitus effects reflex relaxation and dilatation of the corpus uteri (CorU) smooth muscle; that mechanism acts to suck the ejected semen into the CorU. STUDY DESIGN: The CorU response to electrical and mechanical stimulation of the CU was recorded in 22 healthy women (mean age, 38.2 +/- 7.6 SD years). Cervical electrical stimulation was effected by an electromyographic needle electrode and mechanical stimulation by pencil electrode. The test was repeated after individual anesthetization of the CU and CorU and after normal saline injection. RESULTS: Slow waves, superimposed or followed by action potentials, were recorded at rest from the CorU electrode. Electrical or mechanical stimulation of the CU effected a significant reduction of the electric wave parameters and pressure in the CorU; this response was reproducible. Separate stimulation of the anesthetized CU or CorU did not evoke the response, while saline infiltration did. CONCLUSION: CU stimulation resulted in diminished CorU electrical activity and pressure; that presumably indicates uterine wall relaxation. Repeated CU buffeting apparently leads to an intermittent uterine pressure decline, with resulting semen siphonage from the vagina to the uterus. Diminished CorU electrical activity and pressure on cervical stimulation or buffeting might be mediated through the cervicouterine inhibitory reflex. This reflex seems to be evoked by penile thrusting during coitus and may prove of diagnostic significance in sexual disorders.

Action Potentials↗
PubMed2004

Oviduct contractile response to vaginal distension: identification of vagino-tubal reflex.

OBJECTIVE: The effect of vaginal distension on the oviduct contractile activity during penile thrusting at coitus could not be traced in the literature. We investigated the hypothesis that vaginal distension effects oviduct contraction, which assists in ovum transport along the oviduct. METHODS: Oviduct pressure was measured upon vaginal condom distension in 16 women (mean age 32.2+/-1.2 years) scheduled for abdominal hernia repair and oviduct ligation for sterilization. The test was repeated after individual anesthetization of the vagina and oviduct. RESULTS: Ten milliliters vaginal distension effected pressure elevation of the ampullary (AO) and isthmic (IO) parts of the oviduct (p<0.01, p<0.01 respectively) and a decrease in intramural oviduct (IMO; p<0.01). Twenty milliliters distension further increased the pressure in the AO and the IO (p<0.001, p<0.001) and decreased it in IMO (p<0.001). Vaginal distension with greater volumes produced an oviduct pressure response similar to that with 20 ml distension (p>0.05). Vaginal distension of anesthetized vagina or oviduct did not evoke the oviduct pressure response, but saline infusion did. CONCLUSIONS: Vaginal distension seems to produce oviduct motile activity as evidenced by oviduct pressure changes, which appear to assist in sperm-ovum transport and fertilization. These oviduct changes are suggested to occur reflexly through the "vagino-tubal reflex." Pathologic changes of the oviduct presumably interfere with this reflex action, a point that needs to be investigated.

Coitus↗
PubMed2004

Electroesophagogram in gastroesophageal reflux disease with a new theory on the pathogenesis of its electric changes.

BACKGROUND: In view of the disturbed esophageal peristaltic activity and abnormal esophageal motility in gastroesophageal reflux disease, (GERD), we investigated the hypothesis that these changes result from a disordered myoelectric activity of the esophagus. METHODS: The electric activity of the esophagus (electroesophagogram, EEG) was studied in 27 patients with GERD (16 men, 11 women, mean age 42.6 +/- 5.2 years) and 10 healthy volunteers as controls (6 men, 4 women, mean age 41.4 +/- 4.9 years). According to the Feussner scoring system, 7 patients had a mild (score 1), 10 a moderate (score 2) and 10 a severe (score 3) stage of the disease. One electrode was applied to the upper third and a second to the lower third of the esophagus, and the electric activity was recorded. The test was repeated after the upper electrode had been moved to the mid-esophagus. RESULTS: The EEG of the healthy volunteers showed slow waves and exhibited the same frequency, amplitude and conduction velocity from the 2 electrodes of the individual subject, regardless of their location in the upper, middle or lower esophagus. Action potentials occurred randomly. In GERD patients, score 1 exhibited electric waves' variables similar to those of the healthy volunteers. In score 2, the waves recorded irregular rhythm and lower variables than the controls. Score 3 showed a "silent" EEG without waves. CONCLUSION: The electric activity in GERD exhibited 3 different patterns depending on the stages of GERD. Score 1 exhibited a normal EEG which apparently denotes normal esophageal motility. Score 2 recorded irregular electric waves variables which are presumably indicative of decreased esophageal motility and reflux clearance. In score 3, a "silent" EEG was recorded with probably no acid clearance. It is postulated that the interstitial cells of Cajal which are the electric activity generators, are involved in the inflammatory process of GERD. Destruction of these cells appears to occur in grades that are in accordance with GERD scores. The EEG seems to have the potential to act as an investigative tool in the diagnosis of GERD stages.

Adult↗
PubMed2004

Effect of straining on diaphragmatic crura with identification of the straining-crural reflex. The "reflex theory" in gastroesophageal competence.

BACKGROUND: The role of the crural diaphragm during increased intra-abdominal pressure is not exactly known. We investigated the hypothesis that the crural diaphragm undergoes reflex phasic contraction on elevation of the intra-abdominal pressure with a resulting increase of the lower esophageal pressure and prevention of gastro-esophageal reflux. METHODS: The esophageal pressure and crural diaphragm electromyographic responses to straining were recorded in 16 subjects (10 men, 6 women, age 36.6 +/- 11.2 SD years) during abdominal hernia repair. The electromyogram of crural diaphragm was recorded by needle electrode inserted into the crural diaphragm, and the lower esophageal pressure by a saline-perfused catheter. The study was repeated after crural anesthetization and after crural infiltration with saline. RESULTS: The crural diaphragm exhibited resting electromyographic activity which showed a significant increase on sudden (coughing, p < 0.001) or slow sustained (p < 0.01) straining with a mean latency of 29.6 +/- 4.7 and 31.4 +/- 4.5 ms, respectively. Straining led to elevation of the lower esophageal pressure which was coupled with the increased electromyographic activity of the crural diaphragm. The crural response to straining did not occur during crural diaphragm anesthetization, while was not affected by saline infiltration. The lower esophageal pressure declined on crural diaphragm anesthetization. CONCLUSIONS: Straining effected an increase of the electromyographic activity of the crural diaphragm and of the lower esophageal pressure. This effect is suggested to be reflex in nature and to be mediated through the "straining-crural reflex". The crural diaphragm seems to play a role in the lower esophageal competence mechanism. Further studies are required to assess the clinical significance of the current results in gastro-esophageal reflux disease and hiatus hernia.

Action Potentials↗
PubMed2004

Electric activity of the gut in ulcerative colitis and Crohn's disease: electromyography as a tool for differentiating between the two conditions in the early stage.

BACKGROUND: The clinical diagnosis of ulcerative colitis (UC) and Crohn's disease (CD) may overlap and a diagnosis of intermediate colitis is made. We investigated the hypothesis that a difference in the electric pattern of the gut exists between UC and CD which may assist in the differentiation between the 2 conditions in the early stage. MATERIAL/METHODS: The study comprised 16 patients with CD, 18 with UC, and 10 control subjects. It was performed during a scheduled laparotomy. The electric activity was recorded using 3 monopolar electrodes applied to the diseased colonic segments and to the corresponding segments in the control subjects. RESULTS: Regular slow waves (SWs) were recorded in control subjects. They showed the same frequency, amplitude, and conduction velocity from the 3 electrodes of the individual subjects. The SWs were followed or superimposed by action potentials (APs). In CD, edematous segments recorded SWs having wave variables lower than those of the controls; APs were less frequent. No SWs were registered from scarred gut segments. In UC, SWs had a higher frequency but lower amplitude and conduction velocity than those of control subjects; APs were more frequent. CONCLUSIONS: Electrocolography is suggested to act as an investigative tool in differentiating between UC and CD. The electric activity presented with a "tachyrhythmic" electrogram in UC and "bradyrhythmic" or "silent" electrogram in CD.

Adult↗
PubMed2004

Identification of interstitial cells of Cajal in the human rectum.

It is postulated that the electric waves of the gut are generated by interstitial cells of Cajal (ICC). We hypothesized the presence of ICC in the rectum as initiating the rectal electric activity. The current study investigated this hypothesis. Two rectal specimens were taken from healthy areas of excised rectum of 22 rectal cancer patients (age 44.6+/-.2 SD years, 12 men, 10 women). The study specimens were subjected to c-kit immunohistochemistry. Controls for antisera specificity consisted of tissue incubation with normal rabbit serum substituted for the primary antiserum. C-kit positive branched ICC-like cells were detected in the rectal musculature of the studied specimens. They were distinguishable from the c-kit-negative non-branched smooth muscle cells and from the c-kit positive but non-branched mast cells. Immunoreactivity was absent in the negative controls. We have identified in the rectum for the first time cells with morphologic and immunologic phenotypes similar to the ICC of the gut. The role of these cells in normal physiologic and pathologic conditions of the rectum needs further studies.

Adult↗
PubMed2004

Does the crural diaphragm share in the contractile activity of the costal diaphragm? The concept of an "autonomous esophageal crus" and its role in esophageal competence.

BACKGROUND: We investigated the hypothesis that the esophageal crus (EC, part of the crus surrounding the esophagus) is an "individual muscle" and does not share in the contractile activity of the costal diaphragm (CD). MATERIAL/METHODS: The electric activities of the EC and the costal diaphragm (CD) were recorded in 21 subjects (12 men, 9 women, aged 41.6+/-10.4 years) scheduled for laparotomy. One needle electrode was introduced into the EC, one into each vertebral crus (VC), and one in the CD. Recording was performed before and after diaphragmatic paralysis by curarization. While the diaphragm was paralyzed, the responses of the EC and the 2 VCs to CD stimulation were registered. RESULTS: The CD had significantly higher resting motor unit action potentials (MUAPs) than the EC and the 2 VCs (p<0.05), and the EC higher MUAPs than the 2 VCs (p<0.05). During diaphragmatic contraction on inspiration or by stimulation (5 square pulses, 1 ms apart, threshold 32.2+/-6.3 mA), the MUAPs of the CD increased significantly (p<0.01), while those of the EC or VCs exhibited no significant change (p<0.05). CONCLUSIONS: The current findings suggest that the EC is an autonomous muscle which does not share in the contractile activity of the CD. The EC seems to be essentially involved in the competent mechanism of the lower esophagus and has no role in respiratory function.

Abdominal Muscles↗
PubMed2004

The electrovesicogram in the overactive bladder: role in determining pathogenesis and diagnostic significance.

We investigated the hypothesis that the abnormal contractility of the smooth musculature of the overactive bladder (OAB) may be due to derangement of its electrical activity. Percutaneous electrovesicography was performed in 22 patients (mean age 46.3 years, 12 men, ten women) with OAB and 14 healthy volunteers (mean age 45.6 years, eight men, six women). Recording was performed with the bladder full and empty. Three electrodes were applied suprapubically and one reference electrode was applied to a lower limb. Reproducible regular triphasic slow waves (SWs) were recorded in the volunteers. The pattern of the full and empty bladder were similar except for the higher amplitude of the waves in the former (P < 0.05). The OAB patients showed a "dysrhythmic" pattern with irregular frequency, amplitude and conduction velocity in both the empty and full bladders. We obtained tachyrhythmic, bradyrhythmic and arrhythmic areas in the same recording. The OAB exhibited a "dysrhythmic" electrical pattern with areas of different electrical activity in the same recording. The tachyrhythmic, bradyrhythmic and arrhythmic areas are suggested to explain the abnormal vesical contractions and clinical manifestations of OAB. Further studies are required to investigate the cause of the dysrhythmic pattern and the electrovesicogram is suggested as an investigative tool in OAB diagnosis.

Action Potentials↗