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Biomedical subjects

D Z Lubowski

Publications and source records attributed to D Z Lubowski.

At least 19 recordsLinked to original sources
PubMed1999

Basal pressure patterns and reflexive motor responses in the human ileocolonic junction.

This study aimed to determine whether a sustained high-pressure zone exists at the human ileocolonic junction (ICJ) and whether the motor responses of ICJ are consistent with sphincteric function. In 10 subjects with temporary ileostomies, a high-pressure zone was identified using a manometric pull-through with a mean pressure of 9. 7 +/- 3.2 mmHg and length of 4.8 +/- 1.2 cm. Prolonged recordings using a sleeve sensor confirmed sustained tone in the ICJ and superimposed phasic pressure waves (4-8 counts/min) occupying 35% of fasted state. A meal increased ICJ tone (P = 0.0001) and the proportion of time occupied by phasic activity to 50% (P = 0.013). Terminal ileal propagating pressure wave sequences inhibited ICJ phasic activity, and sequences not extending to the cecum reduced ICJ tone (9.0 +/- 7.2 to 5.6 +/- 6.3 mmHg; P = 0.04). Cecal distension increased ICJ tone (8.9 +/- 4.4 mmHg to 11.7 +/- 4.9 mmHg; P = 0.005). The ICJ response to ileal distension was variable and depended on resting tone at the time of distension. We conclude that the human ICJ has sustained tone with superimposed phasic activity. Tone is augmented by cecal distension or a meal and is inhibited by ileal propagating pressure waves. Response to ileal distension is variable but suggests control by descending excitatory and inhibitory pathways.

Adult↗
PubMed1996

Rectal mucosal electrosensitivity - what is being tested?

The results of rectal mucosal electrosensitivity (RME) testing have been used to support theories regarding the aetiology of both idiopathic constipation and bowel dysfunction following rectopexy. The aim of this study was to assess the validity of tests of RME. Sixty-eight patients, comprising three groups (group 1: 50 patients undergoing assessment in the Anorectal Physiology Unit, group 2: 10 patients with coloanal or ileoanal anastomosis, group 3: 8 patients with a stoma) underwent mucosal electrosensitivity testing, with the threshold stimulus required to elicit sensation being recorded. In addition the RME was measured in groups 1 and 2 when placing the electrode, mounted on a catheter with a central wire, against the anterior, posterior, right and left rectal or neorectal walls. To asses the influence on this test of loss of mucosal contact due to faeces, a further 8 cases with a normal rectum had RME performed with and without a layer of water soaked gauze around the electrode to stimulate faeces and prevent the electrode from making contact with the rectal mucosa. There was marked variance in the sensitivity of the different regions of rectal wall tested (P < 0.001). In group 1 patients the mean sensitivities were: central 36.6 mA, anterior 27.4 mA, posterior 37.9 mA, right 22.3 mA and left 25.6 mA. This circumferential variation suggests that the pelvic floor rather than rectal mucosa was being stimulated. All patients in group 2 had recordable sensitivities, and the mean sensitivity threshold was significantly higher than group 1 patients in the central (P = 0.03), right (P = 0.03) and left (P = 0.007) positions. In group 3 the sensitivity was greater within the stoma at the level of the abdominal wall muscle than intra-abdominally or subcutaneously, again suggesting an extra-colonic origin of the sensation. The sensitivity threshold was significantly greater with the electrode wrapped in gauze (P < 0.01), and loss of mucosal contact was not detected by the EMG machine. Therefore RME testing would seem not to measure mucosal sensitivity, and is probably influenced by the presence of faeces.

Electric Stimulation↗
PubMed1996

Results of colectomy for severe slow transit constipation.

PURPOSE: This study assesses the outcome of a standardized operation performed by two surgeons for severe idiopathic slow transit constipation that was resistant to laxative treatment. METHODS: Fifty-nine consecutive patients, 4 men and 55 women, with a mean age of 42.3 years, underwent colectomy with ileorectal anastomosis. Slow colonic transit was demonstrated in each case. Fifty-two patients were available for follow-up, with median time to follow-up being 42 (range, 3-81) months. RESULTS: Median bowel frequency was 4 per 24 hours. Sixty-nine percent had four or less bowel movements daily. Ten percent used antidiarrheal medication regularly. One patient had a stoma for recurrent severe constipation. Mean continence score was 1.8 (on a scale of 0-20); six patients were incontinent, and four of these six had normal preoperative anal manometry. Fourteen patients (27 percent) had difficulty with rectal evacuation. Preoperative defecating proctography was a poor predictor of postoperative evacuation difficulties. Twenty-seven patients (52 percent) had persisting abdominal pain, but there was a significant improvement in the degree of pain (P <0.00001). Forty-seven patients (90 percent) were satisfied with the outcome of the operation (and would elect to have it done again). Dissatisfied patients had recurrent constipation or diarrhea and incontinence. CONCLUSION: Colectomy with ileorectal anastomosis produces a satisfactory functional outcome in the majority of patients undergoing surgery for severe constipation with proven slow colonic transit.

Adolescent↗
PubMed1996

Regeneration of nerve fibres across a colonic anastomosis in the guinea-pig.

Resection and re-anastomosis of the bowel interrupts enteric neuronal pathways. The reestablishment of neuronal connections across a colonic anastomosis was studied using immunohistochemical, retrograde tracing and physiological techniques. In control guinea-pig proximal colon, retrograde labelling with 1,1'-didodecyl-3,3,3,3'-tetramethylindocarbocyanine perchlorate (DiI) revealed that enteric neurons with anally-directed projections are more numerous and have longer axons than orally-projecting neurons. In resected bowel, up to 26 weeks after re-anastomosis, descending neuronal pathways were substantially interrupted. Immunohistochemical labelling of nerve fibres revealed that some enteric nerve fibres did regenerate across narrow regions of the anastomosis, growing preferentially in the oral to anal direction. However, nerve fibres immunoreactive for neurofilament protein triplet were substantially depleted in myenteric ganglia anal to the anastomosis, even after the longest recovery periods, demonstrating that axonal regrowth was limited. This was confirmed in retrograde tracing studies, as no nerve cell bodies oral to an anastomosis were labelled when DiI was placed on myenteric ganglia just anal to the anastomosis. Physiological studies confirmed that regrowth of nerve fibres across the anastomosis occurred and that it was asymmetric, as electrical stimulation led to aboral conduction across the anastomosis more reliably than oral conduction, as measured by circular muscle contraction. After resection and re-anastomosis of the colon, the disruption of neuronal pathways in the enteric nervous system was observed, with limited and preferential re-establishment of aborally-directed long connections.

Anastomosis, Surgical↗
PubMed1996

Stimulated gracilis neosphincter: a new procedure for anal incontinence.

BACKGROUND: The gracilis muscle has been used previously to construct an anal neosphincter, but this was not successful since a short-lived muscle contraction was insufficient to restore continence. Recently, a procedure was described in which conversion to a fatigue-resistant muscle was achieved by chronic low frequency electrical stimulation, and the resultant ability to sustain a constant contraction was associated with improved continence. Our initial results with this procedure, using a standardized operation and treatment protocol in 12 consecutive patients, is reported. METHODS: Seven women (mean age 50 years, range 22-71 years) had faecal incontinence, and five patients (F:M, 3:2; aged 53-72 years) underwent reconstruction after abdominoperineal excision of the rectum for cancer. A detailed questionnaire including continence score was completed pre-operatively. Eight patients have been assessed after ileostomy closure at a mean time of 10 months. RESULTS: Slow-twitch muscle conversion was achieved in each case and all patients have a functional neosphincter. Mean continence score was 6.8 (range 4-12), and seven patients were continent. There was significant improvement in continence in the non-cancer group (p = 0.03). Mean pre-operative resting anal pressure, functional neosphincter pressure (NPfunc), and maximal neosphincter pressure (NP(max)) were 36, 102 and 207 cmH2O, respectively. There was a significant improvement in pressure comparing NPfunc (P = 0.03) and NP(max) (P = 0.03) with pre-operative pressure. Complications included deep vein thrombosis, pulmonary embolism, saphenous nerve injury, leg wound haematoma, and late pacemaker infection. CONCLUSION: The stimulated gracilis neosphincter achieves satisfactory continence in a majority of patients.

Adult↗
PubMed1995

Scintigraphic assessment of colonic function during defaecation.

The aim of this study was to develop a method by which rectal and colonic activity could be examined during defaecation under physiological conditions, in order to evaluate whether the colon plays a role in defaecation. Subjects presented to the Nuclear Medicine department on the day following ingestion of oral In-111 labelled DTPA, when they developed the normal urge to defaecate. Defaecation took place in a private room while dynamic scintigraphy of the rectum and colon was recorded. Fourteen subjects were studied (8 normal subjects, 4 with constipation, 2 with irritable bowel syndrome). In 13 subjects the left colon was visualized during defaecation and emptying was clearly observed in 12. The right colon was visualised in 11 subjects and emptying was seen in 7. Mean percentage segmental evacuation was right colon 20%, left colon 32% and rectum 66%. Colonic emptying occurs during defaecation, which is not a process of rectal evacuation only. This has implications for the understanding of the pathophysiology of obstructed defaecation.

Colon↗
PubMed1995

Autonomic nerves cross the posterior plane of rectal dissection.

This investigation was an anatomical study to determine whether branches of the pre-sacral autonomic plexus cross the posterior plane of surgical dissection to supply the rectum. Initially four cadaver hemi-pelves were dissected. Twelve patients undergoing full rectal mobilization were then studied at operation. In all subjects the pre-sacral nerves were arranged as a plexus below the sacral promontory, rather than as individual left and right nerve trunks. Structures thought to be nerves were identified crossing the plane of posterior mobilization of the rectum. They were traced towards their origin and destination, photographed and representative fibres biopsied. A total of 42 such structures were biopsied (16 in cadavers, 26 in operative cases) and 40 were confirmed to be nerves. These nerves connect the pre-sacral autonomic plexus with the posterior aspect of the rectum and were found at all sacral levels. In the operative cases the level of the positive biopsies were S1-six, S2-six, S3-five, S4-four, S5-three. The posterior plane of rectal dissection is therefore crossed by autonomic nerves that innervate the rectum. The pre-sacral nerves have been found to form a plexus in all subjects.

Adult↗
PubMed1995

Obstructed defecation: current status of pathophysiology and management.

Obstructed defecation poses a challenging clinical problem and in many patients presenting with this syndrome the underlying pathophysiology cannot be determined. Up to now, attempts to diagnose and treat obstructed defecation (anismus) have focused on the function of the somatic pelvic floor musculature surrounding the anorectum, and concepts such as 'puborectalis paradox' and 'spastic pelvic floor' have gained widespread acceptance despite there being no objective data to support such concepts. New evidence showing that defecation is an integrated process of colonic and rectal emptying suggests that anismus may be much more complex than a simple disorder of the pelvic floor muscles. In a small number of patients obstructed defecation is caused by a more simple mechanism, such as internal sphincter hypertonia or a large rectocele, which is easily corrected surgically. Careful selection of patients for treatment, based on identifying the underlying pathophysiological disorder, is emphasized.

Anal Canal↗
PubMed1994

Bisacodyl reduces the volume of polyethylene glycol solution required for bowel preparation.

PURPOSE: This study was designed to compare the efficacy and patient tolerance of standard orthograde bowel preparation using 4 liters of polyethylene glycol solution with only 2 liters of polyethylene glycol preceded by the stimulant laxative bisacodyl. METHODS: Three hundred eighty-two consecutive patients undergoing outpatient colonoscopy under two surgeons over a six-month period were randomized to receive one of the two preparations. Patients were asked to record the effects of the preparation and to give it a "discomfort rating" on a scale from 1 to 5. Surgeons were blinded to the preparation used and rated the quality of bowel cleansing on a scale of 1 to 5. One hundred ninety-one patients were randomized to the 4-liter preparation and 191 to the 2-liter preparation. RESULTS: Ninety-three percent of patients in the 2-liter group drank all of the solution as opposed to only 66 percent of patients in the 4-liter group. Patients in the 4-liter group gave the preparation significantly lower comfort scores than those in the 2-liter group (Fisher's exact test; P = 0.0001). The quality of bowel cleansing was not significantly different between the groups (P = 0.88). A total of 6.8 percent of the 2-liter group and 9.4 percent of the 4-liter group were considered by the surgeon to have had a poor preparation (rating 4 or 5). The quality of the preparation was found to correlate with the patients' age and compliance with the preparation regimen, and was found not to correlate with presenting symptoms, pathology, or a previous colonic resection. CONCLUSION: Bowel preparation with bisacodyl and 2 liters of polyethylene glycol is more acceptable to patients than a 4-liter regimen and is equally effective in cleansing the colon.

Adult↗
PubMed1994

Cimetidine preserves non-specific immune function after colonic resection for cancer.

Fifty consecutive patients undergoing resection of colorectal cancer were randomized to either receive cimetidine at a dose of 400 mg bd for a minimum of 5 pre-operative days, then intravenously for 2 postoperative days, or to act as controls. Baseline immune function was determined in all patients by in vitro testing of lymphocyte proliferation (LP) in response to mitogen, skin testing for cell mediated immunity (CMI) and measurement of lymphocyte subsets. Immune function was retested in both groups on the second postoperative day. In control patients the mean postoperative LP value was 41% of pre-operative levels (P < 0.0001) and the mean CMI reduced to 29% (P < 0.0001). Patients treated with cimetidine had no significant fall in these parameters. Numbers of T and natural killer (NK) cells fell after surgery in both groups, and B cell numbers were maintained in the cimetidine group. It is concluded that cimetidine reduces the immunosuppression that follows colonic resection.

Aged↗
PubMed1993

The cough response of the anal sphincter.

Rises in intra-abdominal pressure are common and are accompanied by reflex contraction of the external sphincter. Voluntary contraction of the sphincter is an uncommon event but is routinely used as a measure of sphincter strength. Cough pressure and squeeze pressure were compared in 75 patients using a 4 channel perfused catheter (3 anal and 1 rectal side-hole). Maximum anal cough pressure was higher than squeeze pressure (mean 158 vs 133 cm H2O, P = 0.0015). Intra-individual variance was less using cough pressure (mean 20% vs 29%, P = 0.005). There was significant overall correlation between cough pressure and squeeze pressure (P < 0.001) although in some cases there were wide differences, suggesting that use of both cough and squeeze pressure in manometry will assess sphincter strength more reliably. Measurement of the recto-anal pressure gradient during coughing correlated significantly better with degree of incontinence than cough or squeeze pressure (P = 0.005). The presence of a positive gradient was 100% specific for incontinence but the sensitivity was only 43% suggesting that factors other than simple mechanical sphincter weakness are involved in incontinence. Measurement of cough pressure has both clinical and research importance and should be added to standard manometric protocols.

Anal Canal↗
PubMed1993

The anorectal angle is not a reliable parameter on defaecating proctography.

Proctography is a standard method of investigating anorectal disorders. The parameters derived from this X-ray include the anorectal angle. The reproducibility of this measurement was assessed in 43 defaecating proctograms viewed by four observers on two separate occasions. Measurements were made at rest and during defaecation straining. Significant intra- and inter-observer variation was found. The anorectal angle is an inaccurate measurement, and should be interpreted with caution.

Anal Canal↗
PubMed1993

Does squatting reduce pelvic floor descent during defaecation?

Neurogenic faecal and urinary incontinence result from a stretch-induced injury to the pelvic nerves, from difficult childbirth or from chronic straining at stool. It has been suggested that the condition occurs less frequently in societies where the squatting position is used during defaecation, and that squatting may minimize pelvic floor descent. This is a prospective study which evaluates the position of the pelvic floor during defaecation straining in 52 patients. The position of the perineum was measured at rest and during maximal defaecation straining using a perineometer, with the patient in the left lateral, sitting and squatting positions. There was a significant difference in the position of the perineum at rest and on straining between the left lateral position and both the sitting and squatting positions. However, there was no significant difference at rest or on straining between the sitting and squatting positions. These results show that squatting does not reduce pelvic floor descent during defaecation straining, and imply that squatting would not help reverse stretch-induced pudendal nerve damage.

Defecation↗
PubMed1992

Oral colon transit scintigraphy using indium-111 DTPA: variability in healthy subjects.

Oral colon transit scintigraphy using indium-111 diethylene-triamine-pentaacetic acid was performed in 41 healthy subjects (22 females, 19 males) to determine variability with age and sex and to define normal ranges. Repeat studies were performed in 10 females and 9 males to assess intra-subject variability. Females showed slightly but significantly slower colonic transit than men and slightly greater intra-subject variability. There was no correlation between age and colonic transit. The results have implications for the definition of normal ranges.

Adult↗
PubMed1992

Electromyography of the pubococcygeus muscles in patients with obstructed defaecation.

The function of the pubococcygeus muscles during defaecation straining was compared in 10 women with obstructed defaecation and 12 age-matched control subjects. Video-proctography in each patient showed failure to evacuate the rectum and sagging of the pelvic floor during attempted defaecation. Trans-perineal concentric needle electromyography in the puborectalis muscle and transvaginal electromyography in the pubococcygeus muscle was carried out during defaecation straining and during attempted rectal balloon expulsion. Contraction of the pubococcygeus muscle was observed in 10 of the 12 control subjects and in 2 of the 10 patients with obstructed defaecation (P < 0.005). Virtually equal proportions of subjects in each group showed relaxation or contraction of the puborectalis muscle during straining. There was significant perineal descent on straining in the patient group (P = 0.005). This group of patients with obstructed defaecation showed failure of the pubococcygeus muscles to contract, perhaps due to neuropathic weakness of the muscles. The puborectalis muscle did not cause obstructed defaecation in these patients, and the concept of "paradoxical" contraction of this muscle is questioned.

Adult↗