PubMed Health⌕ Search

Biomedical subjects

I Shafik

Publications and source records attributed to I Shafik.

13 recordsLinked to original sources
PubMed2005

Tunica albuginea overlapping: a novel technique for the treatment of erectile dysfunction.

Tunica albuginea (TA) in venogenic erectile dysfunction (VED) was found subluxated and flabby because of degeneration and atrophy of its collagen fibres. This had apparently led to derangement of TA veno-occlusive mechanism. We investigated the hypothesis that overlapping of the subluxated and flabby TA would achieve a competent veno-occlusive mechanism during erection. Tunical overlapping was performed in nine VED patients (age 35.6 +/- 1.6 years). Intracorporal pressure (ICP) was measured pre- and postoperatively. After penile degloving, TA on lateral penile aspect was divided along whole length of corpus cavernosum (CC) and tunical double-breasting for 1-1 1/2 cm was performed. A biopsy was taken from TA and stained with haematoxylin and eosin and Masson's trichrome. Clinical efficiency of the operation was evaluated after 6 months. ICP increased (P < 0.01) postoperatively in the nine patients. The increase was maintained during follow-up period in eight patients and decreased to preoperative level in one. Six months after operation, the eight patients had significantly (P < 0.01) improved scores for the erectile function domain over the preoperative scores. Microscopic examination of TA biopsies showed atrophy of the collagen fibres. Tunical overlapping aims at correction of TA flabbiness, corporal tissue support and improving of veno-occlusive mechanism.

Adult↗
PubMed2004

Overactive corpus cavernosum: a novel cause of erectile dysfunction.

Our recording of the electromyographic (EMG) activity of the corpus cavernosum (CC) in 59 patients with erectile dysfunction (ED) revealed 18 patients who had elevated electric activity, which presumably points to heightened tone of the CC smooth muscles. We investigated the hypothesis that this elevated EMG activity and muscular tone of the CC could be the cause of ED. The study comprised the said 18 subjects with the hypertonic CC muscles as study group (42.6 +/- 5.3 SD years), 15 healthy volunteers (41.8 +/- 5.1 SD years) and 15 patients (41.6 +/- 5.5 SD years) with ED who had not recorded elevated tone of the CC muscles as control group. The EMG activity was registered in the flaccid, erectile and detumescent phases by two electrodes inserted into the CC. Electrocavernosography (ECG) of healthy volunteers recorded in the flaccid phase showed regular slow waves (SW) and random action potentials (APs). The wave variables declined significantly in the erection phase (P < 0.01). In the study group, the SW variables in the flaccid phase increased significantly (P < 0.05) compared with the healthy volunteers and the rhythm was irregular. Erection did not occur with sildenafil but with intracavernosal injection of papaverine, which led to decline of the SW variables (P < 0.05). The control ED group exhibited in the flaccid phase diminished SW variables (P < 0.05) compared with the healthy volunteers. On erection with sildenafil administration, the SW variables showed significant reduction (P < 0.05). CC hypertonicity or 'overactive CC' was identified as a possible cause of ED. An elevated EMG activity of the CC muscle fibres in the flaccid phase presumably denotes hypertonicity of these fibres and their failure to relax to effect erection. The cause of elevated CCEMG activity and presumed muscle hypertonicity is unknown and could be functional or organic. Erection was produced by intracavernosus injection of papaverine and not by sildenafil. This condition of 'overactive CC' should be considered in the diagnosis of ED. However, further studies in the pathogenesis of the condition are warranted.

Action Potentials↗
PubMed2001

Study of the effect of temperature on the rectal function with evidence of thermorectal reflex.

BACKGROUND AND AIMS: Rectal sensation seems to originate from mechanoreceptors which are stimulated by passive rectal filling or active contraction. We investigated the effect of temperature on rectal function. PATIENTS AND METHODS: A balloon was introduced into the rectum of 28 healthy volunteers, filled with 50 ml saline at various temperatures, and rectal pressure was recorded. The test was repeated 30 min and 3 h after rectal anesthetization. RESULTS: Rectal pressure was significantly reduced at 45 degrees and 40 degrees C, showed no change at 37 degrees or 30 degrees C, and was increased at 20 degrees, 10 degrees, and 0 degrees C. At 45 degrees C patients felt rectal pain but no sensation of warmth; at 40 degrees, 37 degrees, and 30 degrees C neither rectal pain nor warm sensation was felt; at 20 degrees C or below rectal pain and cold sensation were perceived. Rectal balloon filling 30 min after anesthetization caused no significant rectal pressure changes or sensation of coldness or warmth; after 3 h, when the anesthetic had waned, the rectal pressure response and sensation were similar to those before anesthetization. CONCLUSIONS: Warm saline appears to cause rectal relaxation and cold saline rectal contraction. Subjects did not perceive sensation of warmth in the rectum but felt cold sensation, which may indicate the presence of cold receptors in the rectal wall. The rectal response to temperature variations is suggested to be reflex in nature as evidenced by its absence on rectal anesthetization. Such reflex, designated "thermorectal reflex," is proposed to mediate the rectal response and is speculated to have clinical significance in rectal dysfunctional and neurogenic disorders.

Adult↗
PubMed2001

Study of the mechanism of rectal motility: the 'mass squeeze contraction'.

The motor physiology of the rectum has remained largely obscure, especially concerning the mechanism of rectal motility. In the current communication we tested the possibility of characterizing the mechanism of rectal motility during filling and evacuation through the study of the rectal electric activity in 16 healthy volunteers (mean age 43.6 +/- 10.8 years; 11 men). Two monopolar silver-silver chloride electrodes were introduced per annum and fixed to the rectal mucosa by suction. The rectum was distended in 10 ml increments of water by means of a balloon-ended catheter inserted into the rectum. The rectal pressure was measured by one catheter placed above and a second one below the rectal balloon, and the 2 catheters were connected to 2 strain gauge pressure transducers. Regular triphasic slow waves or pacesetter potentials (PPs) were recorded from the 2 electrodes at rest. PPs were superimposed or followed randomly by action potentials (APs). APs but not PPs were coupled with elevated rectal pressure. Rectal distension with 10 ml of water caused no significant changes of the rectal pressure or EMG activity. Distension with a mean volume of 27.3 +/- 4.7 ml effected a significant increase (p < 0.05) of the rectal electromechanical activity proximally to the balloon and a decrease distally (p < 0.05) to it. With progressive increase of the rectal distension, the electromechanical activity continued to increase proximally and to decrease distally to the balloon, until, at a mean distending volume of 76.3 +/- 3.7 ml, the balloon was dispelled to the exterior. In conclusion, the identification of the modality of rectal motility during defecation was feasible by recording the rectal electromechanical activity. The rectal contraction is suggested to occur in a 'mass squeeze manner' which squeezes the rectal contents aborally into the anal canal. The recognition of the rectal motor modality appears to be important for the understanding of rectal motility disorders. However, further studies are required to confirm these findings.

Action Potentials↗
PubMed1993

Vascular exchange in the kidney. Regional characterization by multiple indicator tomography.

In previous work with the method of multiple indicator dilution (MID), we have established that a spatially distributed model of transcapillary exchange proposed by Goresky, Ziegler, and Bach (GZB) accurately describes, at the in vivo whole-organ level, the handling of extracellular indicators in the canine renal cortex. To date, however, it has not been possible to assess the key hypothesis that GZB corresponds to the actual local mechanism of exchange in vivo and is not just a compact summary of the kidney's average whole-organ behavior. By adapting the MID method to high speed computed tomography (CT), we are now able to report that the GZB mechanism is an accurate description of renal cortical transcapillary exchange down to volumes of cortical tissue comprising no more than a few per cent of the total cortical mass, i.e., containing no more than a few thousand nephrons. A small bolus of iohexol (radiopaque extracellular indicator) or iodipamide ethyl ester microparticles (radiopaque plasma indicator) injected into the renal artery was followed by CT as it passed through the kidney and into the renal vein. Time-attenuation value curves of the two contrast media obtained from the renal vein and from regions of interest in the cortex were then modeled with the GZB mechanism and with a more complex formulation that includes GZB as a limiting case. When applied to the data, the models converged to GZB as the best fit for each region examined. The GZB mechanism is found to provide excellent agreement with the regional data.

Animals↗
PubMed1989

Effect of magnesium infusion on calcium handling in the rat kidney.

Anaesthesized rats were infused with 100 microliters min-1 of 0.9% saline or saline containing 2 or 4 mmol l-1 of magnesium chloride and renal function was studied. Magnesium had no effect on urine flow rate, excretion of sodium or potassium, or glomerular filtration rate (GFR). Infusion of either dose of magnesium increased calcium excretion and calcium concentration in the urine. The increased urinary calcium excretion is due to a decrease in tubular reabsorption of calcium.

Animals↗
PubMedDate not supplied

Role of tunica albuginea in erection: is it a dynamic or a static role?

The tunica albuginea (TA) of the penis is claimed to share in erectile mechanism by compressing the emissary veins passing through it. Apparently this claim is theoretical as no experimental studies could be traced in literature proving this concept. We investigated the hypothesis that TA acts as a cover to corpora cavernosa (CC) and spongiosa (CS) and does not have an active role in erectile mechanism. Penises of 9 dogs were degloved and TA was divided at upper, middle and lower 1/3 of the penis. The intracorporal and glans penis (GP) pressures were measured in the TA-covered and non-covered parts of CC and CS in the flaccid and erectile phases. Sham operation, without performing the TA incisions, was done in 7 control animals. In the test animals, intracorporal pressure (ICP) in the non-TA covered corpora and in GP recorded in flaccid phase a mean of 12.2 +/- 0.8 cmH2O for CC and 11.3 +/- 0.7 cmH2O for the CS and GP, and in the erectile phase 98.4 +/- 8.6 and 76.2 +/- 9.3 cmH2O, respectively. There was no significant difference between covered and non-covered corpora or between test and control animals. In conclusion, the TA seems to act as a cover to the corporal tissue. Its absence did not change ICP.

Animals↗
PubMedDate not supplied

Interstitial cells of Cajal in erectile dysfunction.

The corpora cavernosa (CC) evokes electric activity. Slow waves (SWs) appear to originate from interstitial cells of Cajal (ICCs), which seem to control the activity of the smooth muscle cells (SMC). The ICCs were demonstrated to exist in the CC. We investigated the hypothesis that the ICC distribution differs with each of the various ED types. The study comprised 62 men with ED: 16 neurogenic (NGED), 15 arteriogenic (AGED), 11 venogenic (VGED) and 22 psychogenic (PGED). 15 volunteers with normal erections acted as controls. The patients underwent a complete diagnostic evaluation. A biopsy of 3 x 3 mm from the CC was subjected to C-kit immunohistochemistry examination. Specificity control of the antisera consisted of incubation of the tissue with normal rabbit serum substituted for the primary antiserum. C-kit positive stellate-appearing cells resembling those of ICC were detected in the controls. The branches were either laterally located (multipolar) or lying at each pole (bipolar). They were distinguishable from the SMC, which were C-kit negative. ICC were detected in all specimens from patients with NGED and VGED, absent in 13/15 with AGED and scanty in PGED. ICC distribution was different in the various types of ED. It is suggested that this distribution interferes with SW discharge and the control of SMC activity with a resulting ED.

Adult↗
PubMedDate not supplied

Sperm DNA fragmentation.

Several techniques have been developed to measure the amount of sperm DNA damage in an effort to identify more objective parameters for evaluation of infertile men. The integrity of sperm DNA influences a couple's fertility and helps predict the chances of pregnancy and its successful outcome. The available tests of sperm DNA damage require additional large-scale clinical trails before their integration into routine clinical practice. The physiological/molecular integrity of sperm DNA is a novel parameter of semen quality and a potential fertility predictor. Although DNA integrity assessment appears to be a logical biomarker of sperm quality, it is not being assessed as a routine part of semen analysis by clinical andrologists. Extensive investigation has been conducted for the comparative evolution of these techniques. However, some of these techniques require expensive instrumentation for optimal and unbiased analysis, are labor intensive, or require the use of enzymes whose activity and accessibility to DNA breaks may be irregular. Thus, these techniques are recommended for basic research rather than for routine andrology laboratories. Sperm chromatin structure evaluation is applied to detect male factors that may affect the chance of success with IVF as well as natural fertility. Further research is needed to define the optimal test of sperm chromatin structure. The clinical application of this test will evolve as well.

Apoptosis↗
PubMedDate not supplied

Molecular andrology as related to sperm DNA fragmentation/sperm chromatin biotechnology.

Genetic male infertility occurs throughout the life cycle from genetic traits carried by the sperm, to fertilization and post-fertilization genome alterations, and subsequent developmental changes in the blastocyst and fetus as well as errors in meiosis and abnormalities in spermatogenesis/spermatogenesis. Genes encoding proteins for normal development include SRY, SOX9, INSL3 and LGR8. Genetic abnormalities affect spermatogenesis whereas polymorphisms affect receptor affinity and hormone bioactivity. Transgenic animal models, the human genome project, and other techniques have identified numerous genes related to male fertility. Several techniques have been developed to measure the amount of sperm DNA damage in an effort to identify more objective parameters for evaluation of infertile men. The integrity of sperm DNA influences a couple's fertility and helps predict the chances of pregnancy and its successful outcome. The available tests of sperm DNA damage require additional large-scale clinical trials before their integration into routine clinical practice. The physiological/molecular integrity of sperm DNA is a novel parameter of semen quality and a potential fertility predictor. Although DNA integrity assessment appears to be a logical biomarker of sperm quality, it is not being assessed as a routine part of semen analysis by clinical andrologists. Extensive investigation has been conducted for the comparative evaluation of these techniques. However, some of these techniques require expensive instrumentation for optimal and unbiased analysis, are labor intensive, or require the use of enzymes whose activity and accessibility to DNA breaks may be irregular. Thus, these techniques are recommended for basic research rather than for routine andrology laboratories.

Biotechnology↗
PubMedDate not supplied

Urethral sphincters response to cavernosus muscles stimulation with identification of cavernoso-urethral reflex.

The functional activity of the urethral sphincters during cavernosus muscles' contraction at coitus has been poorly addressed in the literature. We investigated the hypothesis that cavernosus muscles' contraction affects reflex contraction of the urethral sphincters to guard against semen reflux into the urinary bladder or urine leakage from the bladder during orgasm and ejaculation. The electromyographic (EMG) response of the external (EUS) and internal (IUS) urethral sphincters to ischio- (ICM) and bulbo- (BCM) cavernosus muscle stimulation was studied in 15 healthy volunteers (9 men, 6 women, age 39.3 +/- 8.2 SD years). An electrode was applied to each of ICM and BCM (stimulating electrodes) and the 2 urethral sphincters (recording electrodes). The test was repeated after individual anesthetization of the urethral sphincters and the 2 cavernosus muscles, and after using saline instead of lidocaine. Upon stimulation of each of the 2 cavernosus muscles, the EUS and IUS recorded increased EMG activity. Repeated cavernosus muscles' stimulation evoked the urethral sphincteric response without fatigue. The urethral sphincters did not respond to stimulation of the anesthetized cavernosus muscles nor did the anesthetized urethral sphincters respond to cavernosus muscle stimulation. Saline infiltration instead of lidocaine did not affect the urethral sphincteric response to cavernosal muscle stimulation. Results were reproducible. Cavernosus muscles' contraction is suggested to effect EUS and IUS contraction. This action seems to be reflex and mediated through the 'cavernoso-urethral reflex.' Urethral sphincters contraction upon cavernosus muscles contraction during sexual intercourse presumably prevents urine leak from the urinary bladder to urethra, prevents retrograde ejaculation, and propels ejaculate from the posterior to the penile urethra. The cavernoso-urethral reflex can act a diagnostic tool in the investigations of patients with ejaculatory disorders.

Adult↗
PubMedDate not supplied

Identification of c-kit-positive cells in the human prostate: the interstitial cells of Cajal.

The prostate exhibits electric activity in the form of slow waves (SWs) and action potentials (APs). As the interstitial cells of Cajal (ICCs) are considered the pacemaker cells which generate the electric waves, we investigated the hypothesis that the prostate contains ICC. Prostatic biopsies were obtained from 15 healthy volunteers (mean age 36 +/- 3.8 SD years). They were subjected to c-kit immunohistochemistry. Controls for the specificity of the antisera consisted of tissue incubated with normal rabbit serum substituted for the primary antiserum. C-kit-positive cells were identified as fusiform with dendritic processes. The cytoplasm was granular and the nucleus large and oval. Mast cells, also c-kit-positive, were round and lacked the dendritic processes. Immunoreactivity was absent in the negative controls. There were cells in the prostate with morphological and immunological phenotypes similar to ICCs of the gut. We predict an abnormal distribution of these cells in prostatic diseases. The study of the integrity of these cells may prove to be a useful investigative tool in the diagnosis of prostatic diseases and in the planning of an appropriate treatment.

Adult↗