Manometric evaluation of constipation--Part I

Tests of anorectal function have evolved into clinically useful investigations, and they should no longer be regarded as esoteric tools. This transformation has led to major advances in understanding, diagnosis, and treatment of defecation disorders, such as constipation. Because constipation is a heterogeneous condition, it cannot be assessed by a single test. Judicious use of anorectal manometry, colon transit study, a test of simulated defecation, and defecography may provide invaluable pathophysiological information. Undoubtedly, examination of rectal and anal pressure activity, rectal sensation, rectoanal reflexes, and the functional morphology of the defecation unit provides more information than any other test of gastrointestinal motor function; however, there is no uniform criteria for defining manometric abnormalities. There is also an urgent need for establishing international standards for manometric techniques and for diagnosis. Nevertheless, knowledge and experience have paved the way for innovative diagnostic techniques and therapeutic approaches for patients with constipation.

Three-dimensional kinematics of wheelchair propulsion

A three-dimensional (3-D) biomechanical model was used to determine upper extremity kinematics of 16 male subjects with low-level paraplegia while performing wheelchair propulsion (WCP). A six-camera VICON motion analysis system was used to acquire the coordinate data of ten anatomic markers. Joint axes for the wrist and elbow were defined along with the planes of motion for the upper arm (humerus) and trunk. The group's mean and standard deviation profiles were graphed for eight of the nine rotations measured during WCP. Variability in the intercycle and intersubject movement patterns were calculated using the root mean square standard deviation (RMS sigma) and the coefficient of variation (CV). Motion pattern similarities were quantified using the coefficient of multiple correlation (CMC). The intercycle (Nc > or = 6) motion patterns of individual subjects were highly consistent, similar, and repeatable during WCP. This was confirmed by low CVc values (3-31%), high CMCc values (0.724-0.996) and RMS sigma c values below 3.2 degrees. For the group, mean values of the propulsion velocity, cadence, and propulsion cycle duration were 89.7 m/min, 66.1 pushes/min, and 0.96 s, respectively. Humeral plane and rotation showed large excursions (76.1-81.6 degrees), while trunk lean and forearm carrying angle displayed relatively small ranges of motion (5.5-10.9 degrees). The intersubject (N3 = 16) motion patterns were less similar compared to individual intercycle patterns. This was evidenced by higher CVc values (12-128%) and lower CMC3 values (0.418-0.935). Intersubject humeral patterns were the most consistent while trunk lean was the least consistent. Intersubject root mean square standard deviations (RMS sigma c) were more than three times the corresponding intercycle values for all nine rotations.

Unexplained chest pain: the hypersensitive, hyperreactive, and poorly compliant esophagus

OBJECTIVE

To determine whether neuromuscular dysfunction of the esophagus causes chest pain in patients in whom no disease is found on cardiac work-up, upper gastrointestinal endoscopy, esophageal manometry, and 24-hour pH studies.

DESIGN

Prospective study.

SETTING

Tertiary referral center.

PATIENTS

24 consecutive patients and 12 healthy controls.

MEASUREMENTS

A new technique, impedance planimetry, was used to measure the sensory, motor, and biomechanical properties of the human esophagus. The impendance planimeter, which consists of a probe with four ring electrodes, three pressure sensors, and a balloon, simultaneously measures intraluminal pressure and cross-sectional areas. This allows calculation of the biomechanical variables of the esophageal wall.

RESULTS

Stepwise balloon distentions from 5 to 50 cm H2O induced a first sensation at a mean pressure (+/- SD) of 15 +/- 9 cm H2O in patients and 30 +/- 11 cm H2O in controls (P < 0.001). Moderate discomfort and pain were reported by 20 of 24 patients (83%) at 26 +/- 9 cm H2O and at 36 +/- 9 cm H2O, respectively, but by none of the controls (P < 0.001). Typical chest pain was reproduced in 20 of 24 patients (83%). In patients, the reactivity of the esophagus to balloon distention was greater (P = 0.01), the pressure elastic modulus was higher (P = 0.02), and the tension-strain association showed that the esophageal wall was less distensible (P = 0.02). Distention excited tertiary contractions and secondary peristalsis at a lower threshold of pressure (P = 0.05) and with a higher motility index in patients than in controls (P = 0.04).

CONCLUSION

In patients with chest pain and normal cardiac and esophageal evaluations, impedance planimetry of the esophagus reproduces pain and is associated with a 50% lower sensory threshold for pain, a 50% lower threshold for reactive contractions, and reduced esophageal compliance.

Periodic rectal motor activity: the intrinsic colonic gatekeeper?

BACKGROUND

Rectal motor activity is incompletely understood. The aim of this study was to characterize the patterns of rectal motor activity and to examine their diurnal variation and their relationships to proximal colonic activity and to meals.

METHODS

We performed a 30-h ambulatory motility study by recording pressure activity at multiple sites in the colon in 18 normal subjects.

RESULTS

During 288 h of recording, discrete bursts of tonic and phasic activity were seen in the rectum of all subjects at night and during the day lasting > or = 3 min, with a predominant frequency of 3 waves/min: periodic rectal motor activity (PRMA). Nocturnally, the number of cycles and the proportion of time occupied by this activity were greater (p < 0.001) and the inter-cycle interval was shorter (p < 0.008) compared with daytime, but the cycle duration was similar. Only 4 versus 5% (nocturnal vs daytime) of cycles propagated aborad, whereas 36 versus 14% (p < 0.01) propagated retrogradely, 16 versus 47% (p < 0.01) occurred simultaneously, and 44 versus 34% were confined to the rectum. There was considerable intra- and intersubject variability. PRMA was not related to meals or to anal motor activity, but 81% of nocturnal and 94% of daytime cycles occurred within 5 min of a motor event in the more proximal colon.

CONCLUSIONS

PRMA is a characteristic feature of the normal rectum and is more frequent at night. The temporal association with motor events in the proximal colon suggests that PRMA is triggered by the arrival of stool or gas in the rectum. Because most cycles are either segmental or are propagated retrogradely, PRMA may serve as an intrinsic braking mechanism that prevents untimely flow of colonic contents, particularly during sleep.

Duodenum as a immediate brake to gastric outflow: a videofluoroscopic and manometric assessment

BACKGROUND & AIMS

Duodenal infusion of HCl or lipid delays gastric emptying. The aim of this study was to assess whether this delay was in part caused by mechanical activity of the duodenum.

METHODS

Synchronized videofluoroscopy and manometry was used in 8 volunteers (5 men and 3 women) to examine contractile and flow patterns during duodenal infusion of 0.9% NaCl, HCl, 5% NaCl, bile, and sodium oleate, each mixed with 20% (wt/vol) barium sulfate.

RESULTS

Within 15-30 seconds of infusion, HCl and 5% NaCl induced frequent large-amplitude contractions greater tha those induced by 0.9% NaCl. Initially, there was rapid dispersion of HCl followed by prolonged, tonic occlusion of the duodenum. The duodenal diameter decreased compared with that observed during 0.9% NaCl or oleate infusion. In contrast, after infusion of oleate or bile, duodenal diameter increased and there were fewer, smaller-amplitude, nonpropagating contractions with prolonged retention of solutions. Barium (20%; wt/vol) did not influence the motility index of any solution.

CONCLUSIONS

HCl and 5% NaCl may restrict gastric outflow by inducing tonic occlusion of the duodenum, whereas bile and lipid may delay clearance by decreasing duodenal tone and contractility. Thus, the duodenum may serve as an immediate brake to gastric outflow either by delaying clearance or by offering rapid tonic resistance.

Manometric responses of human duodenum during infusion of HCl, hyperosmolar saline, bile and oleic acid

Duodenal motor activity is incompletely understood. The purpose of this study was to define the contractile patterns of the duodenum that occur in response to rate controlled injection of various solutions. In nine healthy volunteers we placed a six channel perfused catheter, and recorded pressure activity in the antrum, pylorus and duodenum. Volumes of 10 and 20 mL of 0.9% NaCl, 100 mM HCl (pH 1), 5% NaCl (1711 mOsm/kg), human bile and iso-osmolar sodium oleate were randomly injected into the duodenum at 20 ml/min, starting 15 min after phase III migratory motor complex (MMC). A 20 mL bolus of each solution caused more activity (P < 0.05) than a 10 mL bolus, but the motor pattern was similar. The control, 0.9% NaCl, produced occasional pressure waves, whereas bile and sodium oleate induced more (P < 0.05) activity which consisted of low amplitude, isolated or clusters (2-4 cycle/min) of non-propagating pressure waves that occurred at random sites. In three subjects, oleate produced isolated pyloric phasic contractions. In contrast, HCl and 5% NaCl induced high amplitude pressure waves that were seen either at a single channel or at multiple channels, occurring simultaneously. The motility index was also greater (P < 0.05) than that induced by other solutions. Additionally, within 2 min of infusion, a phase III MMC like pattern was observed in five of the nine subjects who received HCl and three of the nine who received 5% NaCl. A non-nutrient iso-osmolar solution induced occasional motor activity. HCl and hyperosmolar solutions induced more frequent and large amplitude, segmental contractions whereas lipid and bile induced fewer and smaller amplitude contractions. The volume, the pH, the osmolar and the nutrient make up of the infusate may each influence the duodenal motor responses.

Improved engraftment of human cord blood stem cells in NOD/LtSz-scid/scid mice after irradiation or multiple-day injections into unirradiated recipients

Human lymphoematopoietic stem cells engraft in irradiated immunodeficient mice that are homozygous for the severe combined immunodeficiency (scid) mutation. Engraftment levels in C.B-17-scid/scid mice, however, have been low and transient, decreasing the utility of this model for investigation of the development potential and function of human stem cells. In the present study, we have used NOD/LtSz-scid/scid mice as recipients and human cord blood as a source of donor stem cells. Our results demonstrate that NOD/LtSz-scid/scid mice support approximately fivefold higher levels of human stem cell marrow engraftment than do C.B-17-scid/scid mice. Human CD34+ cells are present in the marrow of recipient mice, and the engrafted cells readily peripheralize to the circulation of the host. Terminal differentiation of the stem and progenitor cells into mature progeny is limited. Using a multiple-day injection protocol developed in mice, which allows engraftment of stem cells between congenic mice in the absence of irradiation preconditioning, we observed high levels of human cell engraftment in unirradiated NOD/LtSz-scid/scid recipients after three or five consecutive-day injections. These results demonstrate that NOD/LtSz-scid/scid mice support high levels of human stem cell engraftment and that xenogeneic lymphohematopoietic stem cells can engraft in unirradiated hosts without the need for ablative reconditioning. This model will be useful for the in vivo investigation of human stem cells and for the preclinical analysis of human stem cells for transplantation.

High levels of engraftment with a single infusion of bone marrow cells into normal unprepared mice

Repetitive infusion of 40 million male murine marrow cells (total 200 million cells) into normal unprepared female BALB/c hosts for 5 consecutive days results in high levels of engraftment at 1-25 months postinfusion, as determined by Southern blot analysis using a Y chromosome-specific probe. We investigated the importance of the schedule of injections in this engraftment model. Surprisingly, a single infusion of 200 x 10(6) male BALB/c bone marrow cells analyzed at 7-14 weeks postinfusion resulted in engraftment levels in individual female mice of over 50% with mean values of 25 +/- 2% for 44 individual transplant points. Engraftment levels in spleen and thymus were 14 +/- 1% and 18 +/- 3%, respectively. Including heparin in the infusion increased engraftment in marrow, spleen, and thymus. Administration of the cells over five or 10 separate infusions, rather than in one injection, did not increase engraftment levels. If the infused bone marrow cells seeded equally between host spleen, thymus, and bone marrow, and if all cells engrafted, the bone marrow engraftment seen here approaches the theoretical maximum. This suggests either a large number of available "niches" or the displacement of host marrow cells by infused marrow. The latter possibility is upheld by cell counts per tibia/femur and total seven-factor HPP-CFC/tibia, which were not increased. These data suggest that a single infusion of marrow homes quantitatively to spleen, thymus, and bone marrow, possibly displacing host cells in the process.

Functional colonic and anorectal disorders. Detecting and overcoming causes of constipation and fecal incontinence

Evaluation of constipation and fecal incontinence begins with comprehensive history taking, which may include overcoming a significant psychosocial barrier. Before functional anorectal diseases can be controlled, the fundamental cause must be determined and any underlying disorder corrected. In constipation, a colonic or anorectal motility disorder is often the cause; about half of refractory cases are the result of obstructive defecation. In fecal incontinence, dysfunction of several anatomic or physiologic mechanisms may be the cause. Anorectal manometry is useful in assessment in both disorders. Other helpful tests are colonic-transit measurement in constipation and electrophysiologic tests and defecography in fecal incontinence. Treatment of constipation often includes dietary measures and use of laxatives or prokinetic agents; fecal incontinence may respond to bulking or antidiarrheal agents. In both disorders, some patients have responded to the recently described technique of neuromuscular conditioning with biofeedback. In some cases, surgical repair must be considered.

Engraftment of bone marrow cells into normal unprepared hosts: effects of 5-fluorouracil and cell cycle status

Bone marrow from animals treated with 5-fluorouracil (5FU) competes equally with normal marrow when assessed in vivo in an irradiated mouse, but shows markedly defective engraftment when transplanted into noncytoablated hosts. Using Southern Blot analysis and a Y-chromosome specific probe, we determined the level of engraftment of male donor cells in the bone marrow, spleen, and thymus of unprepared female hosts. We have confirmed the defective engraftment of marrow harvested 6 days after 5FU (FU-6) and transplanted into unprepared hosts and shown that this defect is transient; by 35 days after 5FU (FU-35), engraftment has returned to levels seen with normal marrow. FU-6 marrow represents an actively cycling population of stem cells, and we hypothesize that the cycle status of the stem cell may relate to its capacity to engraft in the nonirradiated host. Accordingly, we have evaluated the cycle status of engrafting normal and FU-6 marrow into normal hosts using an in vivo hydroxyurea technique. We have shown that those cells engrafting from normal marrow and over 70% of the cells engrafting from FU-6 marrow were quiescent, demonstrating no killing with hydroxyurea. We have also used fluorescent in situ hybridization (FISH) analysis with a Y-chromosome probe and demonstrated that normal and post-5FU engraftment patterns in peripheral blood were similar to those seen in bone marrow, spleen, and thymus. Altogether these data indicate that cells engrafting in normal, unprepared hosts are dormant, and the defect that occurs after 5FU is concomitant with the induction of these cells to transit the cell cycle.

Development of a drug delivery system for the treatment of periodontal disease based on bioerodible poly(ortho esters)

Poly(ortho esters) prepared by the condensation of 1,2,6-hexanetriol and an alkyl orthoacetate are viscous, semisolid materials at room temperature that can be injected using a blunt needle. When tetracycline was incorporated into these materials, complete release occurred within about 24 hours, but when small amounts of Mg(OH)2 were incorporated into the polymer release could be extended to many weeks, and a loading of 0.5 wt% resulted in sustained release of about 10 days. When adhesion was tested using bovine teeth, cohesive failure of the pure polymer occurred at a force of about 392 mN cm-2 and cohesive failure of a polymer incorporating 10 wt% tetracycline and 1 wt% (Mg(OH)2 occurred at about 118 mN cm-2. The combination of injectability, dentoadhesiveness and ability to control accurately the release of incorporated antibiotics makes these materials promising candidates for bioerodible delivery systems useful in the treatment of periodontitis. Toxicological studies are currently in progress.

Effect of quinidine on kidney biochemistry and function in male Sprague-Dawley rats

Accumulation of the organic anion p-amino hippurate (PAH) and the organic cation tetraethyl ammonium (TEA) was decreased in renal cortical slices incubated with medium containing quinidine. Renal cortical slice oxygen consumption was also decreased. Quinidine reduced respiratory control index (RCI) and ADP/O ratio in isolated kidney cortex mitochondria. The in vitro data suggest that quinidine can alter renal transport and mitochondrial functions. Intraperitoneal administration of quinidine at 75 mg/kg twice a day for four days inhibited PAH and TEA transport in renal cortical slices. Renal cortical slice oxygen consumption was significantly decreased. Mitochondria showed a significant reduction in ADP/O ratio but no effect on RCI. Serum biochemical measurements indicated significantly elevated blood urea nitrogen. The data suggest that quinidine produces adverse renal effects in vitro and at high doses it produces nephrotoxic effects in vivo.

Impedance planimetry: an integrated approach for assessing sensory, active, and passive biomechanical properties of the human esophagus

OBJECTIVES

Our objective was to study the biomechanical properties and their relationships to the sensory and motor function of the esophagus, which has seldom been examined in humans.

METHODS

We used impedance planimetry, to study these properties. This system measures cross-sectional area (CSA) and intraluminal pressure simultaneously and facilitates calculation of some of the biomechanical properties of the esophageal wall. We performed 15 studies in 12 healthy volunteers. In three subjects, the studies were repeated to test reproducibility.

RESULTS

Stepwise increments in balloon pressure from 5 to 40 cm H2O induced an increase in CSA (mean +/- SD), 91 +/- 27 to 469 +/- 63 mm2, the wall tension 27 +/- 4 to 484 +/- 32 mm x cm H2O, and the strain 0.2 +/- 0.1 to 1.3 +/- 0.3. The tension/strain relationship increased exponentially. The compliance did not change. The threshold for first sensation was 30 +/- 11 cm H2O (mean +/- SD). In three subjects, when the balloon was distended > 40 cm H2O, chest pain was induced at a threshold of 62 +/- 3 cm H2O, and the compliance decreased. Balloon distension induced tertiary contractions and secondary peristalsis at thresholds of 15 +/- 4 cm H2O, and 19 +/- 5 cm H2O. Repeat studies showed good correlation (r = 0.9).

CONCLUSION

Graded balloon distension increases esophageal CSA, wall tension, and strain. When a threshold is reached, tertiary contractions and secondary peristalsis develop at pressures less than 50% of sensory threshold. At higher pressures, chest pain is induced. Impedance planimetry promises to be a simple, objective, reproducible, and comprehensive technique for evaluating the sensory, motor, and viscoelastic properties of the esophagus.

Energy cost of graded work loads & mechanical efficiency of sportsmen

This study was undertaken to determine oxygen consumption at rest and constant graded work loads while exercising on a bicycle ergometer and to compute mechanical efficiency of sportsmen. Thirteen healthy, active, well trained young sportsmen from sports hostel, Sports Authority of India, Hyderabad, were selected and were requested to pedal the bicycle ergometer at 50 watts and 100 watts (300 and 600 kpm) work loads for 18-20 min. The energy cost of the activity at the respective work loads was measured by means of indirect, open circuit respiratory exchange method. The workouts resulted in the oxygen consumption of about 920.4 +/- 77.5 ml and 1475.2 +/- 101.7 ml at 300 and 600 kpm respectively. The gross or absolute mechanical efficiency (AME) were calculated at these work loads. The delta mechanical efficiency (DME) was also computed for the work increment from 300 to 600 kpm by using the amount of oxygen consumed at these work loads. The AME was about 23-24 per cent in both the loads while the DME was found to be 26 per cent. The relationship between anthropometry, resting metabolic rate (RMR), AME and DME was assessed. It was observed that both AME and DME values of these subjects were in the normal range of Swedish and Canadian active young men. These parameters can be used as indicators for assessing sports persons efficiency both in the active and lean periods.

Positive and negative regulation of D-type cyclin expression in skeletal myoblasts by basic fibroblast growth factor and transforming growth factor beta. A role for cyclin D1 in control of myoblast differentiation

Differentiation of skeletal myoblasts in culture is negatively regulated by certain growth factors, including basic fibroblast growth factor (bFGF) and transforming growth factor beta (TGF beta). We investigated the effects of bFGF and TGF beta on D-type cyclin expression in skeletal myoblasts. When myoblasts were induced to differentiate in low mitogen medium, expression of cyclin D1 rapidly fell below detectable levels. In contrast, expression of cyclin D3 increased to levels exceeding those present in myoblasts. Expression of cyclin D1 was induced in myoblasts by bFGF and TGF beta (albeit with different kinetics for each factor), while induction of cyclin D3 expression was inhibited by these growth factors. Although these results are consistent with other reports showing induction of cyclin D1 by growth factors, induction of cyclin D3 expression during terminal differentiation of myoblasts and inhibition of this induction by growth factors is surprising. These results suggest that cyclin D3, previously thought to be only a positive regulator of cell cycle progression, may also function in the cellular context of terminal differentiated muscle. Stable expression of cyclin D1 from an ectopic viral promoter inhibits C2C12 myoblast differentiation, but only in those clones where the level of cyclin D1 expression does not significantly exceed that present in control myoblasts stimulated by bFGF. Together, these result suggest that cyclin D1 expression functions in the inhibition of myoblast differentiation by certain growth factors.

Ectopic expression of cyclin D1 prevents activation of gene transcription by myogenic basic helix-loop-helix regulators

Activation of muscle gene transcription in differentiating skeletal myoblasts requires their withdrawal from the cell cycle. The effects of ectopic cyclin expression on activation of muscle gene transcription by myogenic basic helix-loop-helix (bHLH) regulators were investigated. Ectopic expression of cyclin D1, but not cyclins A, B1, B2, C, D3, and E, inhibited transcriptional activation of muscle gene reporter constructs by myogenic bHLH regulators in a dose-dependent manner. Ectopic expression of cyclin D1 inhibited the activity of a myogenic bHLH regulator mutant lacking the basic region protein kinase C site, indicating that phosphorylation of this site is not relevant to the mechanism of inhibition. Analysis of cyclin D1 mutants revealed that the C-terminal acidic region was required for inhibition of myogenic bHLH regulator activity, whereas an intact N-terminal pRb binding motif was not essential. Together, these results implicate expression of cyclin D1 as a central determinant of a putatively novel mechanism that links positive control of cell cycle progression to negative regulation of genes expressed in differentiated myocytes.

Mosquito repellency & toxicity of isomeric N, N-diethyltolylacetamides

Three isomers of N, N-diethyltolylacetamides were synthesized and evaluated against Aedes aegypti and Culex quinquefasciatus for repellency and with mice for LD50, as an indicator of mammalian toxicity. Of these, N, N-diethyl-p-tolylacetamide (DEPTA) showed comparatively better repellency against C. quinquefasciatus. All the compounds showed higher repellency against C. quinquefasciatus than Ae. aegypti. In addition, N, N-diethyl-m-tolylacetamide (DEMTA) was found to be least toxic to mice.

Susceptibility of ageing kidney to quinidine

Male Fischer-344 rats aged 3-4 months and 30-32 months were used in this study. Quinidine in vitro reduced accumulation of organic ions, p-ammonium hippurate (PAH) and tetraethyl ammonium (TEA), inhibited oxygen consumption and increased LDH leakage, in renal cortical slices. High concentrations of quinidine (2 and 3 mmol l-1) produced overt toxicity and no age related differences in any of the parameters measured were observed. But at lower concentrations significant age-related differences in kidney susceptibility to quinidine were evident. Administration of 75 mg kg-1 day-1 quinidine for 4 days caused exacerbated renal damage in senescent rats compared to young adults as demonstrated by greater elevation of blood urea nitrogen and serum creatinine, and greater inhibition of TEA uptake in renal cortical slices. These results establish significant age related differences in renal damage due to quinidine.