Therapeutic photobiomodulation for methanol-induced retinal toxicity

Methanol intoxication produces toxic injury to the retina and optic nerve, resulting in blindness. The toxic metabolite in methanol intoxication is formic acid, a mitochondrial toxin known to inhibit the essential mitochondrial enzyme, cytochrome oxidase. Photobiomodulation by red to near-IR radiation has been demonstrated to enhance mitochondrial activity and promote cell survival in vitro by stimulation of cytochrome oxidase activity. The present studies were undertaken to test the hypothesis that exposure to monochromatic red radiation from light-emitting diode (LED) arrays would protect the retina against the toxic actions of methanol-derived formic acid in a rodent model of methanol toxicity. Using the electroretinogram as a sensitive indicator of retinal function, we demonstrated that three brief (2 min, 24 s) 670-nm LED treatments (4 J/cm(2)), delivered at 5, 25, and 50 h of methanol intoxication, attenuated the retinotoxic effects of methanol-derived formate. Our studies document a significant recovery of rod- and cone-mediated function in LED-treated, methanol-intoxicated rats. We further show that LED treatment protected the retina from the histopathologic changes induced by methanol-derived formate. These findings provide a link between the actions of monochromatic red to near-IR light on mitochondrial oxidative metabolism in vitro and retinoprotection in vivo. They also suggest that photobiomodulation may enhance recovery from retinal injury and other ocular diseases in which mitochondrial dysfunction is postulated to play a role.

Renal failure and vestibular toxicity in an adolescent with cystic fibrosis receiving gentamicin and standard-dose ibuprofen

Gentamicin and standard-dose ibuprofen were administered to an adolescent with cystic fibrosis who developed renal failure and severe vestibulotoxicity. A contributing factor was possible suboptimal intravascular volume status. Because of the potential severity of this drug interaction, hydration status and renal and vestibular functions should be closely monitored in patients receiving ibuprofen and intravenous aminoglycosides concomitantly.

Differential recovery of retinal function after mitochondrial inhibition by methanol intoxication

PURPOSE

The authors' laboratory has previously documented formate-induced retinal toxicity in a rodent model of methanol intoxication. These studies determined functional, bioenergetic, and structural recovery of the retina after methanol intoxication.

METHODS

Rats were intoxicated with methanol, and retinal function was assessed by electroretinography 72 hours after the initial dose of methanol and after a 72-hour recovery period. Retinal energy metabolites, glutathione (GSH) concentrations, and histology were determined at the same time points.

RESULTS

Both rod-dominated and UV-cone-mediated electroretinogram responses were profoundly attenuated in methanol-intoxicated rats. In rats allowed to recover from methanol intoxication, there was significant, although incomplete, recovery of rod-dominated retinal function. However, there was no demonstrable improvement in UV-cone-mediated responses. Retinal adenosine triphosphate (ATP), adenosine diphosphate (ADP), and GSH concentrations were significantly reduced after intoxication. Although retinal energy metabolites returned to control values after the recovery period, retinal GSH remained significantly depleted. Histopathologic changes were apparent in the photoreceptors after methanol intoxication, with evidence of inner segment swelling and mitochondrial disruption. In animals allowed to recover from methanol intoxication, there was no evidence of histopathology at the light microscopic level; however, ultrastructural studies revealed subtle photoreceptor mitochondrial alterations.

CONCLUSIONS

These findings support the hypothesis that formate inhibits retinal mitochondrial function and increases oxidative stress. They also provide evidence for a differential sensitivity of photoreceptors to the cytotoxic actions of formic acid, with a partial recovery of rod-dominated responses and no recovery of UV-cone-mediated responses.

Increased mitochondrial K(ATP) channel activity during chronic myocardial hypoxia: is cardioprotection mediated by improved bioenergetics?

Increased resistance to myocardial ischemia in chronically hypoxic immature rabbit hearts is associated with activation of ATP-sensitive K(+) (K(ATP)) channels. We determined whether chronic hypoxia from birth alters the function of the mitochondrial K(ATP) channel. The K(ATP) channel opener bimakalim (1 micromol/L) increased postischemic recovery of left ventricular developed pressure in isolated normoxic (FIO(2)=0.21) hearts to values (42+/-4% to 67+/-5% ) not different from those of hypoxic controls but did not alter postischemic recovery of developed pressure in isolated chronically hypoxic (FIO(2)=0.12) hearts (69+/-5% to 72+/-5%). Conversely, the K(ATP) channel blockers glibenclamide (1 micromol/L) and 5-hydroxydecanoate (5-HD, 300 micromol/L) attenuated the cardioprotective effect of hypoxia but had no effect on postischemic recovery of function in normoxic hearts. ATP synthesis rates in hypoxic heart mitochondria (3.92+/-0.23 micromol ATP. min(-1). mg mitochondrial protein(-1)) were significantly greater than rates in normoxic hearts (2.95+/-0.08 micromol ATP. min(-1). mg mitochondrial protein(-1)). Bimakalim (1 micromol/L) decreased the rate of ATP synthesis in normoxic heart mitochondria consistent with mitochondrial K(ATP) channel activation and mitochondrial depolarization. The effect of bimakalim on ATP synthesis was antagonized by the K(ATP) channel blockers glibenclamide (1 micromol/L) and 5-HD (300 micromol/L) in normoxic heart mitochondria, whereas glibenclamide and 5-HD alone had no effect. In hypoxic heart mitochondria, the rate of ATP synthesis was not affected by bimakalim but was attenuated by glibenclamide and 5-HD. We conclude that mitochondrial K(ATP) channels are activated in chronically hypoxic rabbit hearts and implicate activation of this channel in the improved mitochondrial bioenergetics and cardioprotection observed.

Alpha-1 adrenoceptor blockade: potential new treatment for anal fissures

PURPOSE

Patients with chronic anal fissures are known to have high resting anal pressures that return to normal after successful surgical treatment. Internal anal sphincter activity is increased by sympathetic excitatory innervation via alpha adrenoceptors. The objective of this study was to determine the effect of alpha-1 adrenoceptor blockade on anal sphincter pressure in patients with and without chronic anal fissures.

METHODS

The effect on the anal canal pressure profile of a single oral 20 mg dose of indoramin, an alpha-1 adrenoceptor antagonist, on seven patients with chronic anal fissure and six healthy patients without a fissure was investigated.

RESULTS

Indoramin reduced anal resting pressures in those with anal fissure by a mean of 35.8 percent, from 106.9 +/- 22.15 cm H2O to 68.6 +/- 20.35 cm H2O, and in those without anal fissure by a mean of 39.9 percent, from 84.17 +/- 27.46 cm H2O to 52.17 +/- 24.78 cm H2O, after one hour. This pressure reduction persisted at three hours, and its magnitude is comparable to that obtained after internal sphincterotomy. The pressure reduction occurred over the whole length of the anal canal.

CONCLUSION

It is proposed that alpha-1 adrenoceptor antagonists could be a suitable treatment for chronic anal fissure and other painful conditions where reduction in anal pressure is warranted.

Development and characterization of a rodent model of methanol-induced retinal and optic nerve toxicity

Methanol is an important public health and environmental concern because of the selective actions of its neurotoxic metabolite, formic acid, on the retina, optic nerve and central nervous system. Humans and non-human primates are uniquely sensitive to methanol-induced neurotoxicity as a consequence of the limited capacity of primate species to oxidize and thus detoxify formic acid. The toxic syndrome in primates is characterized by formic acidemia, metabolic acidosis and blindness or serious visual impairment. Nonprimate species are normally resistant to the accumulation of formate and associated metabolic and visual toxicity. We have characterized retinal and optic nerve toxicity in a nonprimate model of methanol toxicity using rats in which folate-dependent formate oxidation has been selectively inhibited, allowing formate to accumulate to toxic concentrations following methanol administration. Methanol-intoxicated rats developed formic acidemia, metabolic acidosis and visual toxicity analogous to the human methanol poisoning syndrome. Visual dysfunction was manifested as reductions in the electroretinogram and the flash-evoked cortical potential which occurred coincident with blood formate accumulation. Histological studies revealed mitochondrial disruption and vacuolation in the retinal pigment epithelium, photoreceptor inner segments and optic nerve. The temporal relationship between methanol administration and the onset and development of ocular toxicity, as well as, the degree of metabolic acidosis and extent of formic acidemia in this rodent model are remarkably similar to that documented in human methanol intoxication. Moreover, the functional and morphologic findings in methanol-intoxicated rats are consistent with the hypothesis that formate acts as a mitochondrial toxin in the retina and optic nerve. The establishment and characterization of this nonprimate animal model of methanol intoxication will facilitate research into the mechanistic aspects of methanol toxicity and the development and testing of treatments for human methanol poisoning.

Ischemic preconditioning in rats: role of mitochondrial K(ATP) channel in preservation of mitochondrial function

We examined the role of the sarcolemmal and mitochondrial K(ATP) channels in a rat model of ischemic preconditioning (IPC). Infarct size was expressed as a percentage of the area at risk (IS/AAR). IPC significantly reduced infarct size (7 +/- 1%) versus control (56 +/- 1%). The sarcolemmal K(ATP) channel-selective antagonist HMR-1098 administered before IPC did not significantly attenuate cardioprotection. However, pretreatment with the mitochondrial K(ATP) channel-selective antagonist 5-hydroxydecanoic acid (5-HD) 5 min before IPC partially abolished cardioprotection (40 +/- 1%). Diazoxide (10 mg/kg iv) also reduced IS/AAR (36.2 +/- 4.8%), but this effect was abolished by 5-HD. As an index of mitochondrial bioenergetic function, the rate of ATP synthesis in the AAR was examined. Untreated animals synthesized ATP at 2.12 +/- 0.30 micromol x min(-1) x mg mitochondrial protein(-1). Rats subjected to ischemia-reperfusion synthesized ATP at 0.67 +/- 0.06 micromol x min(-1) x mg mitochondrial protein(-1). IPC significantly increased ATP synthesis to 1.86 +/- 0.23 micromol x min(-1) x mg mitochondrial protein(-1). However, when 5-HD was administered before IPC, the preservation of ATP synthesis was attenuated (1.18 +/- 0.15 micromol x min(-1) x mg mitochondrial protein(-1)). These data are consistent with the notion that inhibition of mitochondrial K(ATP) channels attenuates IPC by reducing IPC-induced protection of mitochondrial function.

In vitro susceptibility to pexiganan of bacteria isolated from infected diabetic foot ulcers

During two clinical trials involving the treatment of 835 outpatients with infected diabetic foot ulcers, 2515 bacterial isolates, including 2337 aerobes and 178 anaerobes, were grown from cultures of the ulcers. The in vitro susceptibility of these isolates was determined to pexiganan, a peptide anti-infective evaluated in these clinical trials, and to other classes of antibiotics. Pexiganan demonstrated broad spectrum antimicrobial activity against Gram-positive and Gram-negative aerobes and anaerobes. The MIC90 values for the most common species among 1735 Gram-positive aerobes isolated, such as Staphylococcus aureus, coagulase-negative staphylococci, Group A streptococci, and Group B streptococci, were 16 micrograms/mL or less. Of 602 Gram-negative aerobes tested, the MIC90 values for pexiganan were 16 micrograms/mL or less for Acinetobacter, Pseudomonas, Stenotrophomonas, Citrobacter, Enterobacter, Escherichia, Klebsiella, and Flavobacterium species. Pexiganan had a MIC90 of 4 to 16 micrograms/mL against the anaerobic isolates of Bacteroides, Peptostreptococcus, Clostridium, and Prevotella species. Importantly, pexiganan did not exhibit cross-resistance with other commonly used antibiotics, including beta-lactams, quinolones, macrolides, and lincosamides. The broad spectrum in vitro antimicrobial activity of pexiganan against clinical isolates from infected diabetic foot ulcers supports its potential as a local therapy for infected diabetic foot ulcers.

Formate-induced inhibition of photoreceptor function in methanol intoxication

Formic acid is the toxic metabolite responsible for the retinal and optic nerve toxicity produced in methanol intoxication. Previous studies in our laboratory have documented formate-induced retinal dysfunction and histopathology in a rodent model of methanol intoxication. The present studies define the time and concentration dependence of formate-induced retinal toxicity in methanol-intoxicated rats. Retinal function was assessed 24, 48, and 72 h after the initial dose of methanol by flicker electroretinographic measurements. Retinal histopathology was assessed at the same time intervals. Rod- and cone-mediated electroretinogram (ERG) responses were attenuated in a formate concentration- and time-dependent manner, and both retinal sensitivity and maximal responsiveness to light were diminished. Attenuation of UV-cone-mediated responses was temporally delayed in comparison to the functional deficits observed in the 15 Hz/510 nm responses, which have a rod-mediated component and occurred at significantly higher formate concentrations. Both 15 Hz/510 nm and UV-cone-mediated ERG responses were undetectable by 72 h; however, if light intensity was increased, a retinal ERG response could be recorded, indicating that photoreceptor function was profoundly attenuated, but not abolished, under these intoxication conditions. Functional changes preceded structural alterations. Histopathological changes were most pronounced in the outer retina with evidence of inner segment swelling, photoreceptor mitochondrial disruption, and the appearance of fragmented photoreceptor nuclei in the outer nuclear layer. The nature of both the functional and structural alterations observed are consistent with formate-induced inhibition of mitochondrial energy production, resulting in photoreceptor dysfunction and pathology.

Radiographic evidence of silicosis risk in the diatomaceous earth industry

There is limited and conflicting evidence regarding the exposure-response relationship between exposure to crystalline silica and silicosis; the level of risk to current workers remains uncertain. We conducted an epidemiologic investigation of 1,809 workers in the diatomaceous earth industry, where exposures to crystalline silica are primarily to the cristobalite form. On the basis of the median of three independent readings, 81 (4.5%) workers were judged to have opacities on chest radiographs (small opacities, profusion >= 1/0, and/or large opacities). Age-adjusted relative risk of opacities increased significantly with cumulative exposure to crystalline silica. The concentration of respirable crystalline silica to which workers were exposed (highly correlated with period of hire) was an important determinant of risk after accounting for cumulative exposure. For workers with an average exposure to crystalline silica of <= 0.50 mg/m3 (or hired >= 1950), the cumulative risk of opacities for a cumulative exposure to crystalline silica of 2.0 mg/m3-yr was approximately 1.1%; for an average exposure > 0.50 mg/m3 (or hired < 1950), the corresponding cumulative risk was 3.7%. These findings indicate an exposure-response relationship between cumulative exposure to crystalline silica and radiographic opacities; moreover, the relationship was substantially steeper among workers exposed at the highest average concentrations of crystalline silica.

Very-low-birthweight infants at seven years: an assessment of the health and neurodevelopmental risk conveyed by chronic lung disease

To determine whether history of chronic lung disease (CLD) in children born at very low birthweight (VLBW) confers additional risk for impaired health, growth, and neurodevelopment, 17 VLBW children born in 1984 who had CLD (requiring supplemental oxygen more than 30 days after birth) in infancy and 28 VLBW children who did not have CLD were assessed at age 7 years. Assessments included a medical history, standard physical and neurological examinations, pulmonary-function tests, and tests of neuropsychological and psychoeducational functioning. Health status did not differ between the groups. In contrast, children with CLD did not perform as well in neuropsychological and psychoeducational assessments. Although CLD confers little added risk to health, it seems to add significantly to risks for poor school performance that are known to be associated with very low birthweight.

Pharmacokinetics of amiloride after inhalation and oral administration in adolescents and adults with cystic fibrosis

STUDY OBJECTIVE

To compare the pharmacokinetics and systemic exposure of nebulized and oral amiloride in adolescents and adults with mild to moderate cystic fibrosis (CF).

DESIGN

Open-label, randomized, two-way crossover, single-dose pharmacokinetic study.

SETTING

University hospital clinical research unit.

PATIENTS

Nine adolescents and 10 adults with mild to moderate CF (forced expiratory volume in 1 sec > or = 50% predicted, Brasfield score > or = 15).

INTERVENTIONS

Patients received amiloride solution orally (10 mg of amiloride 1-mg/ml solution) and by inhalation [4.5 ml amiloride of 1-mg/ml solution in 12% saline (approximately 3.8 mmol/L) by DeVilbiss 646 nebulizer] during two study phases separated by a 7- to 28-day washout period. Serial blood and urine samples were collected for 48 and 72 hours, respectively.

MEASUREMENTS AND MAIN RESULTS

After oral dosing, the mean +/- SD maximum peak concentration (Cmax) was 20.6 +/- 10.0 ng/ml at 3.2 +/- 1.2 hours in adults and 21.7 +/- 4.88 at 2.9 +/- 0.6 hours in the adolescents. Mean area under the concentration-time curve (AUC) from time zero to infinity hours was 275 +/- 115 and 254 +/- 60 ng.hr/ml in the adult and adolescent groups; half-life was 16.0 +/- 0.7 and 13.4 +/- 1.4 hours, respectively. After nebulization, 14 of 19 subjects exhibited two concentration peaks (Cmax1 and Cmax2) with mean values of 1.57 +/- 1.67 ng/ml at 0.5 +/- 0.2 hours and 1.37 +/- 1.21 ng/ml at 4.0 +/- 1.0 hours for adults, and 1.49 +/- 0.99 ng/ml at 0.5 +/- 0.1 hours and 1.52 +/- 0.81 ng/ml at 3.3 +/- 0.5 hours for adolescents. Estimated mean +/- SD dose nebulized was 1.91 +/- 0.66 and 2.28 +/- 0.30 mg in the adult and adolescent groups, respectively. Mean +/- SD AUC from time zero to the last measurable plasma amiloride concentration after inhalation was 14.4 +/- 17.6 and 15.4 +/- 10.1 ng.hr/ml in the adults and adolescents. No significant adverse events occurred during the study. Pharmacokinetic parameters were not statistically different between the adolescent and adult groups by route of administration. However significant differences in peak amiloride concentration, AUC, and urinary amiloride excretion were evident when comparing oral versus inhalation administration within each group.

CONCLUSIONS

Mean amiloride plasma concentration peaks and AUC after inhalation were significantly lower than after oral dosing. In addition, the second amiloride plasma concentration peak may be due to oral ingestion of the nebulized amiloride, whereas the earlier Cmax1 after inhalation may be due to pulmonary absorption of amiloride. These results suggest that single-dose amiloride inhalation in patients with mild to moderate CF results in minimal systemic exposure compared with oral dosing, and that drug disposition is similar in adolescents and adults with CF.

Paradoxical puborectalis contraction is a feature of constipation in patients with multiple sclerosis

OBJECTIVE

To study the disturbed anorectal physiology associated with constipation in multiple sclerosis.

METHODS

Anorectal function in 10 patients with clinically definite multiple sclerosis and constipation has been compared with 10 normal persons and 11 patients with idiopathic constipation, without multiple sclerosis.

RESULTS

All 10 constipated patients with multiple sclerosis had difficulty evacuating barium paste during defaecography. In four of these there was complete failure of puborectalis relaxation when straining to defaecate, and in another four there was incomplete puborectalis relaxation. There was no evidence of lower motor neuron involvement of pelvic floor muscles in the multiple sclerosis group.

CONCLUSIONS

Paradoxical puborectalis contraction is common in patients with multiple sclerosis in whom constipation is a symptom. This may be a feature of the disturbed voluntary sphincter control mechanism, analogous to detrusor sphincter dyssnergia in the bladder.

Nasal lavage cytokines in normal, allergic, and asthmatic school-age children

Inflammation can be demonstrated in the airway mucosa of asthmatics, even in the absence of overt symptoms, but the pathogenesis of this chronic inflammation is incompletely defined. It has been suggested that inflammatory cytokines produced by epithelium may play important roles in this process. Therefore, we measured the cytokines interleukin-8 (IL-8), IL-6, and granulocyte-macrophage colony-stimulating factor (GM-CSF) in nasal lavage fluids from school-age children who were (1) "normal" (nonallergic/nonasthmatic), (2) allergic to house-dust mite antigen but nonasthmatic (no history of wheezing), or (3) allergic and asthmatic (history of > or = 10 wheezing episodes). Children underwent a single nasal lavage procedure while asymptomatic and on no anti-inflammatory medications or anti-histamines. In addition to cytokine concentrations, cell counts, differentials, albumin, histamine, and eosinophil cationic protein (ECP) concentrations were determined in nasal lavage fluids. Significant increases in IL-8 and ECP were observed in asthmatics compared with both normals and allergic nonasthmatics. Overall, IL-8 in nasal lavage fluids correlated significantly with ECP. Allergic nonasthmatics did not have significant increases in cytokines or other mediators compared with normal subjects. Concentrations of IL-6 did not differ significantly among the three groups, and GM-CSF was undetectable in all samples tested. We conclude that increased IL-8 production and eosinophil activation are characteristic of the airways of asthmatic children when asymptomatic, and we speculate that IL-8 plays a role in the maintenance of airway inflammation in asthma.

The range of PaO2 variation determines the severity of oxygen-induced retinopathy in newborn rats

PURPOSE

This study was conducted to determine the potential influence of PaO2 fluctuation on the retinal neovascular response known to occur in newborn rats exposed to hyperoxic conditions. As an inherent corollary, the authors also defined the relationship between the fraction of inspired oxygen (FiO2) and the arterial blood oxygen tension (PaO2) in newborn rats.

METHODS

Experiment 1 was composed of several oxygen-exposure protocols in which atmospheres of 10% oxygen concentration were alternated with different higher levels of ambient oxygen (50%, 40%, 30%, and room air). In experiment 2, two alternating oxygen concentrations were made to converge toward room air (20.9% oxygen) with each successive group of four treatment groups. These included another group exposed to alternating 50% and 10% oxygen, a group exposed to alternating 45% and 12.5% oxygen concentrations, one exposed to alternating concentrations of 40% and 15% oxygen, and a final group exposed to 35% and room air oxygen concentrations. In each case, oxygen was alternated between the two exposure concentrations every 24 hours. The term delta FiO2 is used to designate the difference in the two oxygen concentrations to which a treatment group was subjected, applying the units of fraction of inspired oxygen (i.e., delta FiO2 = 0.4 for the exposure to alternating 50% and 10% oxygen). At birth, litters of albino rats were placed in each of these environments for 13 or 14 days, after which PaO2 and retinal vascular development were assessed in some rats. The remainder were removed to room air for 4 days before the incidence and severity of abnormal neovascularization were measured.

RESULTS

PaO2 and FiO2 were directly and linearly correlated (r2 = 0.998). In experiment 1, the extent of retinal vascular development on removal from oxygen was a linear function of delta FiO2. Retinal neovascularization subsequently occurred in all rats exposed to alternating 50% and 10% or 40% and 10% oxygen concentrations, but only a third of the 30% and 10% exposure group, indicating a minimum threshold for proliferative disease at delta FiO2 = 0.2. In experiment 2, retinal avascularity also increased linearly with increasing delta FiO2. There was a threshold for neovascularization between the exposure to alternating 45% and 12.5% oxygen and the 40% and 15% oxygen exposure (100% versus 4.8% incidence of neovascularization), indicating a requirement of < or = 12.5% oxygen episodes to stimulate a consistent proliferative response.

CONCLUSIONS

These results suggest that PaO2 fluctuation and degree of hypoxia may have more influence on proliferative retinal disease in newborn rats than the extended hyperoxia that has historically received greater attention. Experimental designs that address the inherent differences in pulmonary function between intrinsically healthy animals and compromised premature infants are of substantial value to our understanding of the pathogenesis of retinopathy of prematurity.

Correlates of recurrent wheezing in school-age children. The Physicians of Raleigh Pediatric Associates

Correlates of recurrent wheezing were examined in a case-control study involving 343 children ranging from 7 to 12 yr of age and recruited from a general pediatric practice. Positive skin tests for allergy were observed in 35% of a random sample of children without recurrent wheezing, and in 77% and 90% of children who had experienced from two to four episodes and five or more episodes, respectively, of recent wheezing. By logistic regression analysis, sensitization to dust mite (odds ratio [OR]: 5.2; 95% CI: 3.0 to 9.0), cat (OR: 15.5; 95% CI: 3.4 to 70.8), and Alternaria (OR: 6.8; 95% CI: 2.1 to 21.5) antigens was consistently associated with recurrent wheezing. Sensitization to pollen antigen(s), observed in 60% of allergic children, was not associated with wheezing. A family history of asthma was a significant predictor of recurrent wheezing (OR: 3.2; 95% CI: 1.7 to 5.9) after adjusting for its association with positive skin tests. Environmental tobacco smoke (ETS) exposure was associated with an increased risk of recurrent wheezing in nonallergic children and in allergic females, but not in allergic males. ETS exposure was not associated with positive skin tests for allergy. A history of wheezing with respiratory illness before 2 yr of age was associated with a modest risk of recurrent wheezing between 7 and 12 yr of age (OR: 2.3; 95% CI: 1.2 to 4.6), a risk that did not differ by allergic status or gender. Theoretically, the prevalence of recurrent wheezing in this population could be reduced approximately 65% by controlling exposure to indoor allergens and ETS.

Abnormal internal anal sphincter fibrosis and elasticity in fecal incontinence

PURPOSE

We aimed to investigate the changes in the proportion of collagen and in the elasticity of the internal anal sphincter in patients with neurogenic fecal incontinence.

METHODS

Collagen content was studied in ten patients with neurogenic fecal incontinence (mean age, 51.5 years) and ten controls (age, 58.6 years) using histologic techniques to determine differences between incontinence and health and to determine the effect of aging. Changes in elasticity were also measured in 8 controls (mean age, 63 years) and 13 patients with neurogenic incontinence (mean age, 60 years) by recording the in vitro length-tension relationship of the freshly excised internal anal sphincter.

RESULTS

Incontinent patients had a significantly higher collagen content than controls (55 percent vs. 33 percent; P = 0.013). In incontinent patients the amount of collagen and the patients' ages correlated significantly (P = 0.001). There was a greater increase in stable tension per increase in muscle length in the strips from incontinent patients compared with controls.

CONCLUSIONS

Changes in fibrous tissue content are likely to influence muscle tone and responsiveness of the sphincter in fecal incontinence.

Stapled laparoscopic rectopexy for rectal prolapse

The widespread success of laparoscopic cholecystectomy has led to the development of a wide range of laparoscopic surgical procedures. Procedures for treating rectal prolapse (Procidentia) may constitute some of the best applications for colorectal laparoscopic techniques. A technique of laparoscopic rectopexy performed using the endo-stapler is described. Twenty-nine consecutive patients have undergone laparoscopic rectopexy. The median age was 71 years (52-89), and male:female ratio was 27:2. One procedure had to be converted to open due to ventilatory difficulties. The mean operative time was 95 minutes (50-190). The mean hospital stay was 5 days (4-15). There was no mortality in this series. Morbidity included incisional hernia through a port hole (n = 1), extraperitoneal haematoma (n = 1), and urinary tract infection with retention (n = 1). In conclusion, laparoscopic abdominal rectopexy is a safe and effective technique in the management of rectal prolapse.

Prevalence of bowel dysfunction in patients with multiple sclerosis and bladder dysfunction

Urinary dysfunction is common in cases of multiple sclerosis (MS). The close proximity of those neural pathways which control the bladder to those which control anorectal function might be expected to lead to a high coexistence of bladder and bowel symptoms. Seventy-seven consecutive patients with clinically definite MS attending a uroneurology clinic were interviewed about their bowel function. All patients had clinical evidence of spinal cord disease with varying degrees of impaired mobility and sufficiently severe disturbance of bladder control to seek medical advice. Thirty-six per cent of these patients had constipation. Twenty per cent had "current incontinence", although another 30% had had at least one episode of faecal incontinence more than 3 months previously. Some patients had both constipation and faecal incontinence. A total of 52% currently had at least one bowel symptom. The pattern of bowel symptoms did not correlate with the pattern of urinary disturbance, or the duration of MS, or the degree of disability. Bowel symptoms are common in patients with MS, but even in those with urinary dysfunction are not universal. Whereas bladder dysfunction in MS is clearly related to spinal cord disease, the neurological basis for the bowel dysfunction is less clear.

CO2 laser haemorrhoidectomy--does it alter anorectal function or decrease pain compared to conventional haemorrhoidectomy?

Carbon dioxide (CO2) laser haemorrhoidectomy is feasible and safe provided it is used with care. It is associated with a reduced requirement for post-operative analgesia. The CO2 laser caused no significant alteration in anorectal physiology.

Exposure to alternating hypoxia and hyperoxia causes severe proliferative retinopathy in the newborn rat

Exposure to variable hyperoxia has recently been shown to be much more effective at producing proliferative retinopathy in the newborn rat than exposure to constant hyperoxia. To incorporate a more clinically relevant oxygen-exposure paradigm in our studies, we have now used a cycle between 50 and 10% oxygen and have compared its effects with those found using new exposures to the previously used 80/40% cycle. Starting at birth and continuing for 14 d, rats were exposed to environments that cycled between 50 and 10% oxygen or 80 and 40% oxygen every 24 h. After exposure, some rats were killed for assessment of retinal vascular development. Others were removed to room air for 4 d before killing and evaluation for the presence of abnormal neovascularization--a clinical consequence believed to be promoted by termination of oxygen therapy. The 50/10% cycle resulted in greater retardation of retinal blood vessel development during oxygen than that found in the 80/40% exposure group. After 4 d postexposure in room air, the incidence of preretinal neovascularization was 97% in the 50/10% rats and 72% in the 80/40% group. Clearly, the overall amount of oxygen the subject receives is less critical than other parameters of its administration in producing proliferative retinopathy. Also, the range of variation (40% in both cases) is not the controlling characteristic. Our results suggest that consistency of oxygen level and avoidance of hypoxic levels should be important concerns in neonatal oxygen therapy.

Effect of age, sex and parity on anorectal function

Ninety-one healthy subjects (51 women; age range 16-85 years) were studied prospectively to determine the effect of age, sex and parity on anorectal function. Maximum resting pressure, voluntary contraction pressure, rectal sensation to distension, rectal and mid-anal electrosensitivity, perineal descent, pudendal nerve terminal motor latency and fibre density of the external and sphincter were measured. Sex influenced mean(s.d.) voluntary contraction pressure (148(56) versus 95(43) cmH2O for men versus women, P < 0.0001), perineal descent on straining (1.0(0.5) versus 1.3(0.4) cm, P = 0.02) and fibre density (1.43(0.14) versus 1.52(0.15), P = 0.02). Age influenced resting pressure (r = -0.43, P = 0.0001), perineal position at rest (r = -0.55, P < or = 0.0001), mid-anal electrosensitivity (r = 0.42, P = 0.0001) and rectal electrosensitivity (r = 0.54, P < 0.0001). Parity affected mean(s.d.) voluntary contraction pressure (105(53) versus 75(20) cmH2O for nulliparous versus parous women, P = 0.04) and mid-anal electrosensitivity (5.3(2.3) versus 4.5(2.3) mA, P = 0.02). Increasing age leads to perineal descent at rest, slowed pudendal nerve conduction, a fall in resting anal pressure and decreased anorectal sensory function. Women have a lower and squeeze pressure, greater perineal descent, longer pudendal nerve terminal motor latency and a greater muscle fibre density than men. Parity leads only to lower squeeze pressure.

Oxygen-induced retinopathy in the rat: relationship of retinal nonperfusion to subsequent neovascularization

PURPOSE

To confirm a relationship between oxygen-induced retinal vasoattenuation and subsequent abnormal neovascularization in the newborn rat.

METHODS

Beginning at birth, some litters of Sprague-Dawley rats were exposed to 80% constant oxygen while others received oxygen varying between 40% and 80% in a cyclic fashion. The frequency of the change in inspired oxygen (FiO2) was either 6, 12, 24, or 48 hours. The exposures periods lasted for 14 days, at which time some rats from each exposure group were sacrificed and assessed for retinal vasoattenuation with injection of fluorescein-labeled dextran. The remaining rats from each group were transferred at day 14 from the hyperoxic atmosphere to room air for an additional 4 days. These animals were then killed and assessed for retinal neovascularization by staining for vascular ADPase activity.

RESULTS

Of all rats raised in variable oxygen, 62% exhibited abnormal retinal neovascularization after 4 days in room air. Only 18% of the rats exposed to constant oxygen responded with abnormal neovascularization. Among the four groups of variable oxygen-exposed rats, there was a direct correlation (R2 = 0.96) between degree of retinal avascularity upon removal from oxygen and the propensity for subsequent abnormal neovascularization. Constant oxygen-exposed rats did not exhibit this relationship. This exposure produced the greatest retinal avascularity upon removal from oxygen but the lowest incidence of abnormal neovascularization after 4 days in room air.

CONCLUSIONS

Retinal avascularity may not be the single overriding stimulus for neovascularization in oxygen-induced retinopathy. Other hypotheses bear consideration, including the possibility that variable oxygen leads directly to vascular endothelial cell mitosis, a common retinal manifestation of ischemia-reperfusion.

The role of pudendal nerve innervation in female pelvic floor function

The assessment of motor conduction along the pudendal nerve is an accurate objective measure of pudendal nerve function. Measurement of its latency (that is the time interval between electrical stimulation of the nerve and induced contraction of the external anal sphincter) has been demonstrated to be abnormally long following vaginal delivery, particularly if the delivery was associated with a heavy fetus or a prolonged second stage of labor. The significance of pudendal neuropathy and its relationship to abnormal degrees of descent of the pelvic floor have also been examined in this review.

Defecography in multiple sclerosis patients with severe constipation

PURPOSE

To evaluate defecography in assessment of anorectal function in patients with multiple sclerosis (MS) who have intractable constipation.

MATERIALS AND METHODS

Eleven patients with MS and constipation (10 women, one man) underwent defecography. A total of 130 mL of barium, liquid (20 mL) and paste, was introduced into the rectum. A dab of barium marked the external anal orifice, and, in the women, a tampon soaked with contrast medium marked the vagina. Video radiographic images and supplemental 100-mm static camera images were obtained.

RESULTS

During defecation, six patients had no puborectalis muscle effacement, four patients had partial effacement, and one patient had complete effacement. No rectal emptying occurred in five patients, and emptying was incomplete in the rest. Three patients developed an intussusception, and two developed a posterolateral pouch.

CONCLUSION

Defecography readily demonstrates rectal outlet obstruction and the failure of the puborectalis and anal sphincter muscles to relax. These are frequent findings in MS patients with intractable constipation.

Audit of postanal repair in the treatment of fecal incontinence

PURPOSE

The short-term results of postanal repair for idiopathic fecal incontinence are satisfactory but data on long-term outcome are lacking. This study was carried out to document the short-term and long-term results of this operation and to determine whether preoperative tests predict long-term outcome.

METHODS

Thirty-six patients (33 females; mean age, 57 years) with major idiopathic fecal incontinence operated on by one surgeon were studied. Patients had resting and voluntary contraction anal pressures and pudendal nerve terminal motor latencies (PNTML) measured preoperatively. Symptoms were evaluated at 6 months after operation and again at a median of 25 (range, 6-72) months in all 36 patients. Symptoms were classified as: Group C, no improvement or worse; Group B, minor improvement; and Group A, marked improvement in comparison to the patient's preoperative symptoms. Seventeen patients had postoperative physiology performed.

RESULTS

At 6 months there were 6 (17 percent) patients in Group C, 12 (33 percent) in Group B, and 18 (50 percent) in Group A. At final follow-up there were 17 (47 percent) in Group C, 9 (25 percent) in Group B, and 10 (28 percent) in Group A. Comparison of the preoperative data in the final outcome groups showed (mean +/- SE): Groups A and B vs. Group C--resting pressure, 24.6 +/- 6 cm H2O vs. 40.5 +/- 12.2 (P = 0.2), voluntary contraction pressure, 23.7 +/- 5.7 vs. 11.8 +/- 3.6 (P = 0.09), and PNTML, 3.2 +/- 0.75 mS vs. 3.3 +/- 0.99 (P = 0.8). Mean differences between post-operative and preoperative results were: resting pressure, 28 +/- 8.2 cm H2O (P = 0.003); voluntary contraction pressure, 19.5 +/- 6.7 (P = 0.01); and PNTML, -0.3 +/- 0.29 mS (P = 0.3).

CONCLUSIONS

At 6 months 83 percent of patients had obtained some benefit from postanal repair but only 53 percent maintained this improvement with only 28 percent being markedly better. There was a trend toward a more favorable outcome in patients with greater squeezing pressures preoperatively but other tests were not of long-term predictive value.

Pelvic floor function in multiple sclerosis

The aim of this study was to define pelvic floor function in patients with multiple sclerosis and bowel dysfunction, either incontinence (MSI) or defecation difficulties without incontinence (MSC). Normal controls and patients with idiopathic neurogenic faecal incontinence without multiple sclerosis (FI, disease controls) were also studied. Thirty eight multiple sclerosis patients (20 incontinent, 18 incontinent) 73 normal controls, and 91 FI patients were studied. The FI group showed the characteristic combined sensorimotor deficit previously described in these patients of low resting and voluntary contraction and pressures, increased sensory threshold to mucosal stimulation, and increased pudendal nerve terminal motor latencies and fibre densities. MSI patients had significantly lower anal resting pressures (80 (30-140) cm H2O, median (range) v 98 (30-200), normal controls, p = 0.002) and both MSC and MSI patients had significantly lower anal maximum voluntary contraction pressures (65 (0-260) cm H2O, MSC and 25 (0-100), MSI v 120 (30-300), normal controls, p = < 0.0004) and higher external anal sphincter fibre densities (1.7 (1.1-2.6), MSC and 1.7 (1.1-2.4), MSI v 1.5 (1.1-1.75), normal controls, p < 0.006) compared with normal controls but pudendal nerve terminal motor latencies were similar and no sensory deficit was found. This contrasted with the idiopathic faecal incontinent patients who, in addition to significantly higher fibre densities (1.8 (1.1-3), p = 0.001) had increased pudendal latencies (2.5 (1.1-5.5) mS v 2.08 (1.4-2.6), p = 0.001) compared with normal controls. The idiopathic faecal incontinent group had significantly lower resting anal pressures (50 (10-160) cm H2O, p=0.02) than the MSI group. Comparison with the incontinent and continent multiple sclerosis groups showed that incontinence was associated with lower voluntary anal contraction pressures (25 (0-100) v 65 (0-260), p=0.03) but that there were no other differences between these two groups. Pelvic floor function is considerably disturbed in multiple sclerosis, showing muscular weakness with preservation of peripheral motor nerve conduction, providing indirect evidence that this is mainly a result of lesions within the central nervous system.

Bowel dysfunction: a pathogenic factor in uterovaginal prolapse and urinary stress incontinence

OBJECTIVE

To investigate the aetiological importance of bowel dysfunction in patients with uterovaginal prolapse and urinary stress incontinence.

DESIGN

Observational study using a questionnaire about obstetric history and bowel function, and anorectal physiological studies.

SETTING

Physiology unit and gynaecological outpatients departments of two teaching hospitals.

SUBJECTS

Twenty-three women with uterovaginal prolapse (mean age 57 years), 23 women with urinary stress incontinence (mean age 52 years) and 27 control women (mean age 52 years).

RESULTS

There was no statistically significant difference between the three groups in their parity, age or birthweight of their children. However, straining at stool as a young adult prior to the development of urogynaecological symptoms was significantly more common in women with uterovaginal prolapse (61% vs 4%, P < 0.001) and women with urinary stress incontinence (30% vs 4%, P < 0.05), compared with controls. A bowel frequency of less than twice per week as a young adult was also more common in women with uterovaginal prolapse than in control women (48% vs 8%, P < 0.001). At the time of consultation, 95% of the women with uterovaginal prolapse were constipated, compared with only 11% of control women. Many of these women also needed to digitate to achieve rectal evacuation. Compared with controls, women with uterovaginal prolapse had a prolonged pudendal nerve terminal motor latency (1.9 ms vs 2.2 ms, respectively, P = 0.003). Women with stress incontinence of urine had a normal pudendal nerve latency (2.0 ms). Other tests of anorectal function were normal.

CONCLUSIONS

Constipation, in addition to obstetric history, appears to be an important factor in the pathogenesis of uterovaginal prolapse.

Neuropeptides in the internal anal sphincter in neurogenic faecal incontinence

The internal anal sphincter has both an intrinsic and extrinsic innervation which modulates its activity. While the nature of the extrinsic innervation has been well characterised, the same is not true of the intrinsic innervation. Although a variety of neurotransmitters have been identified in the human internal anal sphincter, their physiological role in health, and possible involvement in disease processes, have received little attention. Using immunohistochemistry we have studied the distribution and nerve fibre densities of a range of neuropeptides in the internal anal sphincter from 12 cancer patients (controls) and from 16 patients with neurogenic faecal incontinence. We have also studied the in vitro effect of vasoactive intestinal peptide, neuropeptide tyrosine, and galanin on isolated preparations of the internal anal sphincter from 11 cancer controls and 5 patients with neurogenic faecal incontinence. There was no difference in either the distribution or density of the neuropeptides between the 2 groups of patients, and there was no qualitative difference in the in vitro responses of the sphincter to the neuropeptides. These findings suggest that these neuropeptide components of the intrinsic innervation of the internal anal sphincter are unaffected in patients with neurogenic faecal incontinence.

Abnormalities of innervation of internal anal sphincter in fecal incontinence

Physiological and histological studies have shown that the internal and sphincter is abnormal in idiopathic fecal incontinence. We have recently demonstrated that the in vitro contractile response of the internal anal sphincter to the sympathetic neurotransmitter noradrenaline is decreased in incontinence. In this study we have further defined this reduced sensitivity and provided more information about the intrinsic innervation in both the normal and the incontinent sphincter muscle. Muscle strips from 12 incontinent patients undergoing post and repair and from 11 controls undergoing rectal excision for low rectal carcinoma were studied. Responses to noradrenaline were recorded initially alone and then in the presence of phentolamine, an alpha-adrenoceptor blocker. In the presence of phentolamine, noradrenaline caused relaxation: there was no significant difference in the relaxation-response curves and the EC50 was the same in the two groups. These results demonstrate that the previously documented reduced sensitivity to noradrenaline is due to an altered sensitivity of the alpha-adrenoceptors. Electrical field stimulation produced relaxations in all muscle strips, but only in the controls was the magnitude of the relaxation significantly increased in the presence of phentolamine. This indicates that there is an alpha-adrenergic excitatory component of the response to electrical field stimulation of the intramural nerves, which was present in tissues from control patients but which was absent in tissues from patients with idiopathic fecal incontinence.

Laparoscopic assisted surgery of the colon. Operative technique

Laparoscopic cholecystectomy is the most common major abdominal operation performed endoscopically. Other surgical procedures performed endoscopically include hysterectomy, hernia repair, Nissen fundoplication, and vagotomy. More recently, laparoscopic colectomy has been described (1,2). We have performed over fifty laparoscopic assisted colonic procedures, the results of which have been published (2). In this paper we describe the technique of two laparoscopic assisted procedures in colonic surgery--right and left hemicolectomy.

Oral or intravenous erythromycin has no effect on human distal colonic motility

Erythromycin is a prokinetic agent for the lower oesophageal sphincter, the stomach, the gallbladder and the small bowel, acting directly on motilin receptors. Its effect on pressure activity of the human colon has not been investigated. Eight healthy volunteers were studied on 2 occasions and given intravenous or oral erythromycin, or placebo in a single-blind, randomized crossover study. Sigmoid pressure activity was measured using a 4-lumen water perfused system placed sigmoidoscopically at 50, 45, 30 and 15 cm from the anal verge. The pressures were analysed for activity index (mmHg.min) for the 35 cm colonic study segment using dedicated software. No significant difference was found in the activity index following oral erythromycin (500 mg) or placebo, or following intravenous erythromycin 1.8 mg/kg or placebo. A further 8 subjects were studied in a single-blind crossover study to determine the effect of oral erythromycin (500 mg) b.d. on colonic transit, measured with radio-opaque markers and a single abdominal X-ray. Mean or segmental colonic transit times were not statistically significantly different (Student's paired t-test) in the subjects on placebo or erythromycin. This lack of effect of erythromycin on the distal large intestine may indicate the absence of receptors for motilin in that part of the gut.

Antemortem diagnosis of cholangiocellular carcinoma in a horse

A 10-year-old Tennessee Walking Horse gelding was admitted to the veterinary teaching hospital for evaluation of intermittent fever, lethargy, and anorexia. Initial laboratory analyses revealed anemia and hyperfibrinogenemia. Abdominocentesis and thoracentesis yielded fluid samples with high nucleated cell counts and total protein concentrations. The tentative diagnosis was nonseptic peritonitis. The horse did not improve after 4 days of antimicrobial treatment, and pitting edema of the ventral midline developed. Thoracic radiography and ultrasonography revealed consolidation of the ventral aspect of the lung fields and pleural effusion. Pleuroscopy of the right hemithorax revealed pleural effusion and a soft-tissue mass in the caudal portion of the mediastinum. Findings on biopsy of the liver and mediastinal mass led to a presumptive diagnosis of metastatic cholangiocellular carcinoma. The horse was euthanatized, and the diagnosis was confirmed at necropsy.

Decreased sensitivity of muscarinic but not 5-hydroxytryptamine receptors of the internal anal sphincter in neurogenic faecal incontinence

Previous studies of the internal anal sphincter in patients with neurogenic faecal incontinence have indicated an abnormality of the adrenergic innervation, but little is known about the responsiveness of other receptors in the internal and sphincter in this condition. In this study the in vitro sensitivity to carbachol and 5-hydroxytryptamine (5-HT) of muscle strips from patients with neurogenic incontinence (n = 6 and n = 7) and from control patients (n = 9 and n = 10) was examined. Preparations of internal and sphincter from patients with incontinence were less sensitive to the relaxant actions of carbachol than preparations from the control group. The pD2 value for carbachol (i.e. the negative logarithm of the concentration for half-maximal response) was significantly greater in the controls than in the incontinent group (mean(s.e.m.) 6.03(0.15) versus 5.43(0.24), P < 0.05). There was no significant difference in the contractile responses to 5-HT, which had pD2 values of 6.93(0.13) and 6.63(0.27) for the control and incontinent groups respectively. The unaffected state of the 5-HT receptor and the subsensitivity of the muscarinic receptor are discussed in relation to intrinsic neural control of the internal and sphincter in neurogenic faecal incontinence.

Respiratory allergy and the relationship between early childhood lower respiratory illness and subsequent lung function

In a study of 159 school-age children whose histories of outpatient visits for lower respiratory illness (LRI) had been documented from early infancy, we observed lower mean levels of small airway function in boys who had experienced two or more episodes of wheezing-associated LRI before 6 yr of age. To determine whether allergy was an important factor influencing this result, we examined relationships among the results of RAST tests for seven common inhalant allergens and concurrent lung function in 126 subjects who consented to venipuncture. Increasing values for the sum of scores for the seven RAST tests were associated with progressively lower mean levels of small airways function in boys with histories of recurrent wheezing LRI during the preschool years. The association of allergy with lower levels of lung function was largely accounted for by dust mite allergy. RAST results were not correlated with lung function in boys who had experienced zero or 1 wheezing LRI before 6 yr of age or in girls. A history of recurrent wheezing LRI during the preschool years was also associated with significantly lower mean levels of small airways function in boys who had negative RAST tests. A subset of 49 boys was reevaluated after an average interval of 4 yr with RAST tests, spirometry, and methacholine challenge. Dust mite allergy was associated with an increased prevalence of bronchial hyperreactivity independent of early childhood wheezing LRI history.(ABSTRACT TRUNCATED AT 250 WORDS)

An infant and toddler feeding group program

At Children's Medical Center of Dayton, Ohio, several children whose early oral feedings were delayed or especially difficult due to physical problems became resistant and exhibited aversive behaviors when oral feeding was introduced. A support group, which lasted for 9 months, was initiated with six of these children and their families. In the group, professionals provided the families with general information about nutrition and behavior and with individualized intervention strategies for the nutritional and behavioral management of their child's specific problems. The families contributed mutual support and problem solving strategies through the group process. Each child demonstrated progress during the 9-month period, which suggests that intervention in a support-group format can be a successful alternative to an individual inpatient program for eating disorders in some young children.

Lung function in school-age children who had mild lower respiratory illnesses in early childhood

We examined the relationship between patterns of mild lower respiratory illness (LRI) experienced in early childhood and lung function in 89 boys and 70 girls 6 to 18 yr of age. The children's histories of outpatient visits for wheezing and nonwheezing LRI during the first 6 yr of life had been documented by physicians in a single pediatric practice. Most children were reported by their parents to have been free of recurrent respiratory symptoms during the 2 yr prior to lung function testing. In sex-specific analyses, average lung function assessed by spirometry was similar in children who had made zero or one physician visit for wheezing LRI during the preschool years. Boys who had experienced two or more episodes of wheezing LRI during the preschool years had lower average FEV1, FEV1/FVC, FEF25-75, Vmax50, and Vmax75 than did boys who had zero or one preschool wheezing illness. The association between recurrent preschool wheezing LRI and later lung function remained after exclusion of data from seven boys who were reported to have wheezed in the 2 yr prior to study. Girls who had experienced two or more preschool wheezing LRI had lower average FEF25-75 and Vmax50 than girls with a history of zero or one such illness, but differences were not statistically significant. Recurrent nonwheezing LRI during the preschool years was not significantly associated with subsequent lung function in either sex, regardless of preschool wheezing LRI history. Detailed information concerning early childhood LRI experience is valuable in epidemiologic studies of factors influencing lung function in children.

Whole blood re-calcification time in equine colic

Whole blood re-calcification times were evaluated as a measure of endotoxin-associated coagulopathy in horses. First, the effects of endotoxin concentration and duration of in vitro incubation of citrated whole blood with endotoxin on the whole blood re-calcification time of blood collected from healthy horses were determined. Increasing concentrations or incubation times of endotoxin accelerated the whole blood re-calcification time. This effect was attributed mainly to increased monocyte thromboplastin activity. Second, whole blood re-calcification time, a clotting profile, plasma factor VII activity and plasma endotoxin concentration on blood samples obtained from 35 equine colic patients and 10 healthy horses were determined. Compared with healthy horses, colic patients had a longer mean whole blood re-calcification and prothrombin time, lower per cent factor VII activity and higher mean fibrin degradation products concentration. Within the colic patient group, horses that did not survive had detectable endotoxin in plasma, longer whole blood re-calcification and prothrombin times, and lower plasma factor VII activity, compared with colic patients that survived. These data indicate that colic patients with endotoxaemia experience hypercoagulable states, followed by consumptive coagulopathy. Although the cause of endotoxin-associated coagulopathy is likely multi-factorial, increased expression of monocyte thromboplastin activity may be involved in the pathogenesis of coagulopathy. The whole blood recalcification time is a simple, fast and inexpensive way to detect coagulopathy during endotoxaemia and determine the prognosis for survival.

Effect of dietary alpha-linolenic acid on endotoxin-induced production of tumor necrosis factor by peritoneal macrophages in horses

A study was conducted to determine whether dietary supplements with alpha-linolenic acid altered the ability of equine peritoneal macrophages to produce tumor necrosis factor (TNF) in response to endotoxin. Peritoneal macrophages were harvested from 6 healthy adult horses before and after the horses were fed a nutritionally balanced ration that contained 8% linseed oil as a source of alpha-linolenic acid. The macrophages were cultured in media containing no additives (control), endotoxin (0.5 to 50 ng/ml), or the calcium ionophore, A23187. Macrophage supernatants were collected after 6 and 24 hours' incubation and stored at -70 C. Tumor necrosis factor activity was estimated by a modified in vitro cytotoxicity bioassay, using the murine fibrosarcoma cell line, WEHI 164 clone 13. The TNF activity after 6 and 24 hours' incubation was greater in culture media of macrophages exposed to endotoxin than in media from control macrophages. For macrophages cultured in media that contained endotoxin, neither the concentration of endotoxin nor incubation time had any effect on TNF activity. Endotoxin-induced macrophage production of TNF, as determined by measurement of TNF activity, was significantly less after horses were fed the alpha-linolenic acid-rich ration for 8 weeks.

Influence of an omega-3 fatty acid-enriched ration on in vivo responses of horses to endotoxin

Because certain inflammatory processes are dependent on the fatty acid composition of the cellular membrane, dietary manipulations that replace omega-6 fatty acids with omega-3 fatty acids may modify inflammatory responses. We investigated the effect of supplemental dietary linseed oil, containing the omega-3 fatty acid, alpha-linolenic acid, on in vivo responses of horses to endotoxin. One group of horses (n = 6) was fed a control pelleted ration (0% linseed oil), and another group of horses (n = 6) was fed an 8% linseed oil pelleted ration. After 8 weeks of consuming these rations, all horses were given 0.03 micrograms of Escherichia coli 055:B5 endotoxin/kg of body weight, infused over 30 minutes. Horses were monitored over 24 hours. Compared with baseline values within each ration group, endotoxin infusion caused significant (P less than 0.05) increase in rectal temperature, heart rate, and plasma concentration of thromboxane B2, 6-keto-prostaglandin F1 alpha, and fibrinogen and significant (P less than 0.05) decrease in total WBC count. Compared with baseline values within each ration group, endotoxin infusion failed to cause significant changes in prothrombin, activated partial thromboplastin, thrombin, or whole blood recalcification times, serum concentration of fibrin degradation products, PCV, or plasma total protein concentration. Before and after endotoxin infusion, horses given the linseed oil ration had longer mean whole blood recalcification time and activated partial thromboplastin time than did horses fed the control ration.

Clinical relevance of monocyte procoagulant activity in horses with colic

Endotoxin-activated monocytes express a thromboplastin-like procoagulant activity on the cell surface that may serve as a focal point for formation of microvascular thrombi. Because coagulopathy is a common sequela to endotoxemia in the equine species, we investigated the ability of monocytes, isolated from horses with colic, to express procoagulant activity. On the day of admission, and on the third and fifth day of hospitalization, monocytes were isolated from 30 adult horses with colic. A coagulation profile, including prothrombin time, activated partial thromboplastin time, thrombin time, and plasma fibrinogen and serum fibrin degradation products concentrations, was determined at each sample collection. The concentration of endotoxin in the plasma was quantitated at the time of admission. Ten clinically normal adult horses served as controls. The procoagulant activity of monocytes isolated from horses with colic was significantly (P less than 0.05) greater than that of the monocytes isolated from clinically normal horses. On the first and third day of hospitalization, the mean prothrombin time was significantly (P less than 0.05) longer in horses with colic, compared with clinically normal horses, and was the most common abnormality in the coagulation profile on the day of admission (25/30; 83%). Mean fibrin degradation products concentration was significantly (P less than 0.05) greater in horses with colic on the day of admission and was the second most common abnormality in the coagulation profile on day 1 (23/30; 77%). In horses with colic, the mean prothrombin and activated partial thromboplastin times were significantly (P less than 0.05) longer in horses that did not survive, compared with horses that survived.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of vaginal delivery on the pelvic floor: a 5-year follow-up

We have studied the pelvic floor musculature and its innervation in 14 of 24 (58 per cent) multiparous women who had been recruited into a study of the effect of childbirth on the pelvic floor as part of a prospective investigation that began in 1983. These 24 women had all delivered by the vaginal route without forceps assistance. Five of the 14 had developed clinical symptoms of stress incontinence 5 years later; two of them had had a further uncomplicated vaginal delivery during this time. There was manometric and neurophysiological evidence of weakness because of partial denervation of the pelvic floor striated sphincter musculature, with pudendal neuropathy, which was more marked in those women with incontinence. These findings provide direct evidence for the hypothesis that pudendal neuropathy due to vaginal delivery persists and may worsen with time.

Adrenergic control of the internal anal sphincter is abnormal in patients with idiopathic faecal incontinence

There is histological and functional evidence that the internal anal sphincter is abnormal in patients with idiopathic faecal incontinence. The in vitro responsiveness of the internal anal sphincter to noradrenaline (an important sympathetic neurotransmitter) and electrical field stimulation (known to stimulate the intrinsic innervation) has been studied. Muscle strips from eight patients with incontinence undergoing postanal repair and five controls undergoing resection for low rectal carcinoma were studied. The contraction-response curves for noradrenaline were significantly different, and the EC50, the concentration required to produce 50 per cent of maximum contraction, was higher in incontinent patients (P less than 0.001). Electrical field stimulation produced initial contractions in four of the control group which were blocked by phentolamine. This contraction was not present in the incontinent patients (P less than 0.01). These results indicate an abnormality in the adrenergic innervation of the internal anal sphincter in patients with idiopathic faecal incontinence.

Clinical assessment and anorectal manometry before postanal repair: failure to predict outcome

It has been suggested that preoperative measurement of resting anal canal pressure and internal sphincter function can be used to identify those patients with neurogenic faecal incontinence who are unlikely to benefit from the operation of postanal repair. We have therefore analysed the results of the operation in 62 patients (six men and 56 women, mean age 59 years, range 30-83 years) and related clinical outcome to preoperative assessment of: resting anal canal pressure, the presence of gape and a combination of gape and low resting pressure. None of these factors was found to predict a poor result after postanal repair.

Effect of postanal repair on progress of neurogenic damage to the pelvic floor

Physiological evaluation of the anorectum and pelvic floor muscles was carried out in 18 patients before and 9-35 months after postanal repair for anorectal incontinence. Thirteen patients (72 per cent) were improved, but in these patients the fibre density in the external anal sphincter muscle and the pudendal nerve terminal motor latency were both increased after surgery. In the five patients not improved after surgery only a few unstable motor unit potentials could be recorded in the external anal sphincter muscle. In two of these patients the pudendal nerve terminal motor latency could not be recorded after surgery. We suggest that this progression in the neurogenic damage to the pelvic floor muscles after postanal repair may be caused by the operation, and that it may be responsible for the poor functional outcome noted in some patients.