Exploring the diversity of AVPR2 in Primates and its evolutionary implications

The current study focuses on the investigation of AVPR2 (VTR2C) protein-coupled receptor variants specific to different primate taxa. AVPR2 is activated by the neurohormone AVP, which modulates physiological processes, including water homeostasis. Our findings reveal positive selection at three AVPR2 sites at positions 190, 250, and 346. Variation at position 250 is associated with human Congenital Nephrogenic Diabetes Insipidus (cNDI), a condition characterized by excessive water loss. Other 13 functional sites with potential adaptive relevance include positions 185, 202, 204, and 252 associated with cNDI. We identified SH3-binding motifs in AVPR2's ICL3 and N-terminus domains, with some losses observed in clades of Cercopithecidae, Callitrichinae, and Atelidae. SH3-binding motifs are crucial in regulating cellular physiology, indicating that the differences may be adaptive. Co-evolution was found between AVPR2 residues and those in the AVP signal peptide/Neurophysin-2 and AQP2, other molecules in the same signaling cascade. No significant correlation was found between these Primates' taxon-specific variants and the bioclimatic variables of the areas where they live. Distinct co-evolving amino acid sequences in functional sites were found in Platyrrhini and Catarrhini, which may have adaptive implications involving glucocorticoid hormones, suggesting varied selective pressures. Further studies are required to confirm these results.

Recommendations on chronic constipation (including constipation associated with irritable bowel syndrome) treatment

While chronic constipation (CC) has a high prevalence in primary care, there are no existing treatment recommendations to guide health care professionals. To address this, a consensus group of 10 gastroenterologists was formed to develop treatment recommendations. Although constipation may occur as a result of organic disease, the present paper addresses only the management of primary CC or constipation associated with irritable bowel syndrome. The final consensus group was assembled and the recommendations were created following the exact process outlined by the Canadian Association of Gastroenterology for the following areas: epidemiology, quality of life and threshold for treatment; definitions and diagnostic criteria; lifestyle changes; bulking agents and stool softeners; osmotic agents; prokinetics; stimulant laxatives; suppositories; enemas; other drugs; biofeedback and behavioural approaches; surgery; and probiotics. A treatment algorithm was developed by the group for CC and constipation associated with irritable bowel syndrome. Where possible, an evidence-based approach and expert opinions were used to develop the statements in areas with insufficient evidence. The nature of the underlying pathophysiology for constipation is often unclear, and it can be tricky for physicians to decide on an appropriate treatment strategy for the individual patient. The myriad of treatment options available to Canadian physicians can be confusing; thus, the main aim of the recommendations and treatment algorithm is to optimize the approach in clinical care based on available evidence.

The Quebec Association of Gastroenterology position paper on colorectal cancer screening - 2003

Colorectal cancer is a leading cause of death and the third most common cancer in Canada. Evidence suggests that screening can reduce mortality rates and the cost effectiveness of a program compares favourably with initiatives for breast and cervical cancer. The objectives of the Association des gastro-entérologues du Québec Task Force were to determine the need for a policy on screening for colorectal cancer in Quebec, to evaluate the testing methods available and to propose one or more of these alternatives as part of a formal screening program, if indicated. Fecal occult blood testing (FOBT), endoscopy (including sigmoidoscopy and colonoscopy), barium enema and virtual colonoscopy were considered. Although most clinical efficacy data are available for FOBT and sigmoidoscopy, there are limitations to programs based on these strategies. FOBT has a high false positive rate and a low detection yield, and even a combination of these strategies will miss 24% of cancers. Colonoscopy is the best strategy to both detect and remove polyps and to diagnose colorectal cancer, with double contrast barium enema also being a sensitive detection method. The Task Force recommended the establishment, in Quebec, of a screening program with five- to 10-yearly double contrast barium enema or 10-yearly colonoscopy for individuals aged 50 years or older at low risk. The program should include outcome monitoring, public and professional education to increase awareness and promote compliance, and central coordination with other provincial programs. The program should be evaluated; specific billing codes for screening for colorectal cancer would help facilitate this. Formal feasibility, effectiveness and cost-effectiveness studies in Quebec are now warranted.

Infliximab for the treatment of Crohn's disease: efficacy, safety and pharmacoeconomics

Crohn's disease is a chronic inflammatory disorder of the gastrointestinal tract. From the perspective of the patient, symptoms of the disease significantly impair quality of life and interfere with activities of daily living. Conventional medical treatment of Crohn's disease includes the use of nonspecific anti-inflammatory drugs, immunosuppressives and antibiotics. These therapies are characterized by a delayed onset of action, incomplete response rates and a substantial risk of adverse effects. Although surgery is frequently used to treat complications, postoperative recurrence is an important problem. Infliximab, a chimeric monoclonal antibody directed toward tumour necrosis factor alpha, is highly effective for the treatment of active Crohn's disease. In randomized, placebo-controlled clinical trials, 82% of patients who received 5 mg/kg of infliximab had a clinically significant response, compared with 17% of those given placebo (P<0.001). Moreover, infliximab is the only medical therapy that has been shown to be effective for the treatment of fistulizing Crohn's disease. Infusion reactions are the most common adverse effect. Whether treatment with infliximab is associated with an increased risk of neoplasia, infection or autoimmune disease is unknown. Therefore, further long term safety studies are required. Despite the relatively high cost of drug acquisition, preliminary pharmacoeconomic analysis indicates that infliximab is cost effective compared with existing treatments. Infliximab is recommended for the treatment of active Crohn's disease refractory to conventional drugs, and is the treatment of choice for fistulizing Crohn's disease.

Management of fistulas in patients with Crohn's disease: antibiotic to antibody

Fistulas are common in patients with Crohn's disease and, when associated with inflammatory disease and established for several weeks, tend to be chronic. Perianal fistulas are the most frequent complication of, and are most often associated with, colonic disease. Perianal fistulas commonly require surgical resection and permanent ileostomy. Antibiotics, cyclosporine, methotrexate and thalidomide have been used in uncontrolled trials; only azathioprine, 6-mercaptopurine and infliximab have been assessed in double-blind, placebo controlled studies. Relapse of the fistula occurs with all drugs, unless treatment is continued long term. Each drug differs in its onset of action and long term tolerability. An approach to fistulizing disease in Crohn's disease is suggested.

Symptom relief in gastroesophageal reflux disease: a randomized, controlled comparison of pantoprazole and nizatidine in a mixed patient population with erosive esophagitis or endoscopy-negative reflux disease

OBJECTIVES

Gastroesophageal reflux disease (GERD) in primary care practice presents symptomatically, and resources to distinguish promptly between erosive esophagitis and endoscopy-negative reflux disease (ENRD) are limited. It is therefore important to determine the roles of proton pump inhibitors and histamine-2-receptor antagonists for first-line symptom-based therapy in patients with erosive esophagitis and ENRD. The aim of this study was to compare pantoprazole 40 mg once daily versus nizatidine 150 mg b.i.d. in a mixed GERD patient population with ENRD or erosive esophagitis (Savary-Miller grades 1-3).

METHODS

A 4-wk randomized, double-blind, parallel-group, multicenter study conducted in Canada. Eligible patients had experienced GERD symptoms > or = 4 times weekly for > 6 months. Patients were randomized to pantoprazole 40 mg once daily or nizatidine 150 mg b.i.d.. Endoscopy was performed before randomization and after 4 wk of therapy.

RESULTS

Of 220 patients randomized to therapy, 208 were available for a modified intent-to-treat analysis. Erosive esophagitis was present in 125 patients; 35 patients were Helicobacter pylori positive. There was complete symptom relief after 7 days of therapy in 14% of patients on nizatidine and in 40% of those on pantoprazole (p < 0.0001), and after 28 days of treatment in 36% and 63% of patients, respectively (p < 0.0001). After 28 days of treatment, adequate heartburn control was reported by 58% of the nizatidine group and in 88% of the pantoprazole (p < 0.0001); erosive esophagitis healing rates were 44% for nizatidine and 79% for pantoprazole (p < 0.001). Rescue antacid was needed by a greater number of patients using nizatidine than of those using pantoprazole (p < 0.001). H. pylori infection was associated with an increased probability of erosive esophagitis healing.

CONCLUSIONS

Pantoprazole once daily was superior to nizatidine b.i.d. in producing complete heartburn relief in a mixed population of GERD patients and in achieving erosion healing. The proportions of patients with complete symptom relief were greater with pantoprazole after 7 days of therapy than with nizatidine after 28 days. The present study data suggest that pantoprazole is a highly effective first-line therapy for the management of gastroesophageal reflux disease in a primary care practice setting.

Double trouble: impact of inappropriate use of asthma medication on the use of health care resources

BACKGROUND

There is considerable controversy about the regular use of short-acting beta-agonists for the treatment of asthma. Although case-control studies have suggested that excessive use of these drugs may worsen asthma control and increase the risk of fatal or near-fatal asthma, the controversy remains unresolved because of the confounding that exists among disease control, disease severity and the use of short-acting beta-agonists. Whatever the cause-and-effect relation between the use of short-acting beta-agonists and disease severity, we hypothesized that their excessive use, in conjunction with underuse of inhaled corticosteroids, would be a marker for poorly controlled asthma and excessive use of health care resources.

METHODS

To characterize the pattern of health services utilization among asthmatic patients taking various doses of inhaled beta-agonists and corticosteroids in British Columbia, we linked the relevant health administrative databases. All patients between 5 and 50 years of age for whom a prescription for a short-acting beta-agonist was filled in 1995 and whose prescription data were captured through the provincial drug plan were included in a retrospective analysis of prescriptions for asthma drugs, physician prescribing patterns and health services utilization. Patients' use of asthma medication was classified as appropriate (low doses of short-acting beta-agonist and high doses of inhaled corticosteroid) or inappropriate (high doses of short-acting beta-agonist and low doses of inhaled corticosteroid), and the 2 resulting groups were compared, by means of logistic, Poisson and gamma regression, for differences in prescribing patterns, physician visits and use of hospital resources.

RESULTS

A total of 23,986 patients were identified as having filled a prescription for a short-acting beta-agonist (for inhalation) in 1995. Of these, 3069 (12.8%) filled prescriptions for 9 or more canisters of beta-agonist, and of this group of high-dose beta-agonist users, 763 (24.9%) used no more than 100 micrograms/day of inhaled beclomethasone. On average, those with inappropriate use of beta-agonists visited significantly more physicians for their prescriptions (1.8 v. 1.4), and each of these physicians on average wrote significantly more prescriptions for asthma medications per patient than the physicians who prescribed to appropriate users (5.2 v. 2.5 prescriptions). Patients with inappropriate use were more likely to be admitted to hospital (adjusted relative risk [RR] 1.68, 95% confidence interval [CI] 1.25-2.26), were admitted to hospital more frequently (adjusted RR 1.81, 95% CI 1.41-2.32) and were more likely to require emergency admission (adjusted RR 1.93, 95% CI 1.35-2.77).

INTERPRETATION

Despite the widespread distribution of guidelines for asthma pharmacotherapy, inappropriate use of asthma medications persists (specifically excessive use of inhaled short-acting beta-agonists combined with underuse of inhaled corticosteroids). Not only are patients who use medication inappropriately at higher risk for fatal or near-fatal asthma attacks, but, as shown in this study, they use significantly more health care resources than patients with appropriate medication use.

Standardization of a simplified scintigraphic methodology for the assessment of gastric emptying in a multicenter setting

OBJECTIVE

Scintigraphy remains the gold standard to study gastric emptying. The technique is onerous and normal values vary between centers. Standardized protocols, although desirable, are not presently available. We validated a simplified scintigraphic protocol in a multicenter setting.

METHODS

In 69 healthy volunteers from seven Canadian institutions, gastric emptying of a standard meal (99mTc-labeled beef liver) was assessed by scintigraphy every 10 min for 1 h, then every 20 min for the next 2 h. Gastric retention was fitted to a power exponential model, Prop(t) = (-(kappat)beta) with Prop(t) = proportion of retention at time t, either using all 13 time intervals (conventional technique) or using measurements at 0, 1, 2, and 3 h (simplified technique).

RESULTS

The power exponential model yielded identical emptying curves and T 1/2 values with both techniques. Gastric emptying was more rapid in men than in women < 35 yr (p<0.01) and in younger than in older men (p<0.005). Gastric emptying was slower in women from Québec than in women from Ontario (p<0.04). Gastric retention was similar at 1, 2, and 3 h among the seven centers. Gastric emptying of a beef liver meal was slower than that of a low fat egg substitute (p<0.03).

CONCLUSIONS

A simpler scintigraphic approach, using four rather than 13 samples, provides results comparable to those of the conventional technique. This simpler approach provides an economical, yet accurate, alternative to the techniques presently used and is applicable to a multicenter setting.

Systematic approach toward the clinical diagnosis of functional dyspepsia

Functional dyspepsia (FD) is the most common condition in patients consulting with upper gastrointestinal tract symptoms, resulting in up to 5% of visits to family physicians. By definition, patients with FD have no clinical, biochemical or endoscopic evidence of an organic disease that is likely to explain their symptoms. The process to be used in a structured interview for establishing a clinical diagnosis of FD is presented. The steps are as follows: determine the duration and the course of the disease; characterize the current syndrome and review the alarm symptoms; elicit the patient-perceived dominant symptom and/or condition; and identify the patient's reason for consulting and address the psychosocial factors. According to the clinical characteristics of the three most frequent causes of dyspepsia (peptic ulcer, gastroesophageal reflux and FD) and acknowledging that these conditions may coexist rather than overlap in some patients, an algorithm is suggested for establishing a working diagnosis of FD and indications for investigation, and initiating a management strategy.

Comparison of ranitidine bismuth citrate plus clarithromycin with omeprazole plus clarithromycin for the eradication of Helicobacter pylori

BACKGROUND

Many dual and triple therapy treatment regimens have been proposed for the eradication of Helicobacter pylori. However, assessing the relative efficacy of these regimens is complicated by differences in study design, and few well-controlled comparative studies have been reported.

METHODS

This multicentre, randomized, double-blind study involved 530 duodenal ulcer patients, of whom 520 had confirmed H. pylori infection. Patients received 14 days b.d. dual therapy of either ranitidine bismuth citrate (RBC) 400 mg or omeprazole 20 mg, both with clarithromycin 500 mg to eradicate H. pylori, followed by a further 14 days of treatment with RBC 400 mg b. d. or omeprazole 20 mg o.d. to facilitate ulcer healing. H. pylori eradication and ulcer healing were assessed at least 26 days after the end of treatment. Adverse events were recorded throughout the study.

RESULTS

H. pylori was eradicated in 90% of patients who received RBC with clarithromycin and in 66% of patients who received omeprazole with clarithromycin (per protocol; P<0.001). intention-to-treat eradication rates were 77% and 60%, respectively (P<0.001). Ulcer healing rates were 97% in the RBC treatment group and 95% in the omeprazole treatment group. Only 3% and 1% of patients in the RBC and omeprazole treatment groups, respectively, were withdrawn due to adverse events.

CONCLUSIONS

RBC with clarithromycin is a simple and highly effective dual therapy regimen for the eradication of H. pylori, and is significantly more effective than omeprazole with clarithromycin. Both treatment regimens are well tolerated and effectively heal duodenal ulcers.

Myopathy following mechanical ventilation for acute severe asthma: the role of muscle relaxants and corticosteroids

BACKGROUND

Acute myopathy following mechanical ventilation for near-fatal asthma (NFA) has been described recently, and some researchers have suggested that this complication is related to the use of neuromuscular blocking agents (NMBAs) and corticosteroids (CSs).

OBJECTIVES

To determine the incidence of acute myopathy in a group of patients and to examine the most important predictors of its development.

DESIGN AND METHODS

A retrospective cohort study over a 10-year period (1985 to 1995) of all asthma patients who received mechanical ventilation at two centers in Vancouver (designated center 1 and center 2).

RESULTS

In center 1, there were 58 patients who had 64 episodes of NFA, and in center 2, there were 28 patients who had 30 episodes. NMBAs were used in 30 of 86 admissions for acute severe asthma (35%). The mean (+/- SD) duration of muscle paralysis was 3.1+/-2.3 days. A total of 9 patients (10.4%) developed significant myopathy. The incidence of myopathy was 9 of 30 (30%) among patients who received NMBAs. In a multiple logistic regression model, the development of myopathy was only significantly associated with the duration of muscle relaxation. The odds ratio for the development of myopathy increased by 2.1 (95% confidence interval, 1.4 to 3.2) with each additional day of muscle relaxation. The dose and the type of the CS were not significantly associated with the myopathy in the multiple logistic regression analysis.

CONCLUSION

Our study showed that there is a high incidence of acute myopathy when NMBAs are used for NFA. The incidence of myopathy increases with each additional day of muscle relaxation.

Quality of Life in Reflux and Dyspepsia patients. Psychometric documentation of a new disease-specific questionnaire (QOLRAD)

OBJECTIVE

To develop a disease-specific QOL instrument (QOLRAD) addressing patient concerns in gastroesophageal reflux disease (GERD) and dyspepsia. Patients. 759 male (45%) and female (55%) patients with a mean age of 48.4 years (sd 15.2) were used in the psychometric evaluation.

MAIN OUTCOME MEASURES

A pilot version of QOLRAD, the Gastrointestinal Symptoms Rating Scale (GSRS) and the SF-36 were completed prior to endoscopy. Items with a high ceiling effect, items measuring a different construct, i.e. with a low squared multiple correlation (R < 0.5) with the other items, items that showed redundancy by a high correlation (>0.80) with another item were removed. A confirmatory factor analysis was also performed.

RESULTS

The final questionnaire included 25 items depicting problems with emotions, vitality, sleep, eating/drinking, and physical/social functioning. The internal consistency reliability was high (alpha value overall 0.97, dimensions 0.89-94). Construct validity, i.e. the associations between similar constructs in the QOLRAD, the SF-36 and the GSRS scores was confirmed. Pain and symptom severity were markers of impaired QOL. The impact on health-related QOL was similar across the functional gastrointestinal disorders with the exception of patients with a normal endoscopy, who did slightly worse.

CONCLUSION

The QOLRAD is a short and user-friendly instrument with excellent psychometric properties. Its responsiveness to change in (AVMC1) clinical trials is currently being explored.

Efficacy of omeprazole in functional dyspepsia: double-blind, randomized, placebo-controlled trials (the Bond and Opera studies)

BACKGROUND

The efficacy of H2-receptor antagonists in functional dyspepsia is equivocal and the therapeutic place of proton pump inhibitors in functional dyspepsia is unknown.

AIM

To evaluate the efficacy of proton pump inhibitor therapy in functional dyspepsia.

METHODS

Patients (n = 1262) with a clinical diagnosis of functional dyspepsia (persistent or recurrent epigastric pain or discomfort for at least 1 month and a normal upper gastrointestinal endoscopy) were randomized to receive omeprazole 20 mg, 10 mg or identical placebo, for 4 weeks. Symptoms were assessed using validated measures. Helicobacter pylori status was determined pre-entry by a 13C-urea breath test.

RESULTS

On an intention-to-treat analysis (n=1248), complete symptom relief was observed in 38% on omeprazole 20 mg, compared with 36% on omeprazole 10 mg and 28% on placebo (P = 0.002 and 0.02, respectively). Among those with ulcer-like and reflux-like dyspepsia, complete symptom relief was achieved in 40% and 54% on omeprazole 20 mg, and 35% and 45% on omeprazole 10 mg, respectively, compared with 27% and 23% on placebo (all P < 0.05, except omeprazole 10 mg in ulcer-like dyspepsia, P = 0.08). There was no significant benefit of omeprazole over placebo in dysmotility-like dyspepsia. Symptom relief was similar in H. pylori-positive and negative cases.

CONCLUSIONS

Omeprazole is modestly superior to placebo in functional dyspepsia at standard (20 mg) and low doses (10 mg) but not in patients with dysmotility-like dyspepsia.

Altered frequency of a promoter polymorphic allele of the kinin B1 receptor gene in inflammatory bowel disease

BACKGROUND & AIMS

Evidence of kinin-mediated inflammation in the gastrointestinal tract is accumulating. The genes and some polymorphic sites have been characterized for both kinin B1 and B2 receptors. These candidate genes were studied for their possible association with inflammatory bowel disease (IBD).

METHODS

In a retrospective study, the prevalence of allele pairs for four polymorphic sites of the two kinin receptor genes was determined in 53 patients with IBD and in 110 healthy volunteers similar in age, body weight, and gender proportions, using polymerase chain reaction and other techniques.

RESULTS

Only the B1 receptor promoter polymorphism (G-699-->C) exhibited a significantly different allele frequency between the two groups (prevalence of the C allele of 5.7% in patients with IBD compared with 33.6% in controls; P = 0.0002) or between the controls and either etiologic subgroup (ulcerative colitis and Crohn's disease). Allelic polymorphisms affecting exon 3 of the B1 receptor gene (A1098-->G) or exon 2 (C181-->T) or 1 (a 9-base pair deletion) of the B2 receptor gene were found to be neutral.

CONCLUSIONS

The gene corresponding to the B1 receptor for kinins may be a nonetiologic marker of symptomatic IBD, as suggested by the altered prevalence of a polymorphism presumably affecting its regulation.

A comparative study of elastic properties of rat and guinea pig parenchymal strips

Constricted guinea pig (GP) airways are much less sensitive to changes in transpulmonary pressure (Ptp) than are those of the rat. The object of this study was to investigate whether differences in the mechanical behavior of the lung parenchyma could explain differences between the two species in the interdependence of the airway and parenchyma. Subpleural lung strips from guinea pigs and rats were excised and suspended in an organ bath. One end of each strip was attached to a force transducer and the other to a servo-controlled lever arm that effected length (L) changes in the strip. Sinusoidal oscillations at varying frequencies and amplitudes were applied at different resting tensions. Measurements of L and resting tension (T) were recorded during baseline conditions and after acetylcholine (ACh) challenge. Elastance (E) and resistance (R) were calculated by fitting changes in T and L to the equation of motion. During sinusoidal oscillations, E and R in the two species were different in both the unconstricted and constricted states. The effect of T on E was significantly different in rats and GPs; E was less dependent on T in GPs. Insofar as E is a measure of the load against which airway smooth muscle (ASM) contracts, this difference may represent a potential mechanism to explain why constricted GP airways are less sensitive to changes in Ptp.

Correlation between pulmonary fibrosis and the lung pressure-volume curve

The severity of pulmonary fibrosis is the main prognostic factor for survival of patients with interstitial lung diseases (ILD). Unfortunately, lung biopsy, which is the best method to assess fibrosis quantitatively, is done only once during the evolution of the disease. In this study we analyzed the relationship between the degree of fibrosis and the exponential constant k, derived from the lung pressure-volume curve (LPVC) in 33 patients with chronic ILD, 19 with pigeon breeder's disease (PBD), and 14 with idiopathic pulmonary fibrosis (IPF). Pulmonary function tests, including the LPVC, were obtained before biopsy. A semiquantitative histologic assessment of the severity of fibrosis was performed on lung tissues. All patients showed a decrease of total lung capacity, residual volume, compliance, and Pao2. The mean value of the constant k was 0.08 +/- 0.06. When expressed as a percent of normal values, 25 patients exhibited values of k lower than 70% of predicted; of the remaining 8 patients whose values were above 70% of predicted, 7 had PBD and only one IPF. On morphologic analysis, 19 patients displayed more than 50% fibrosis. No significant correlations were found between the extent of the lesion or severity of lung fibrosis and the conventional pulmonary function tests. By contrast, a moderate but significant correlation was found between k and the severity of lung fibrosis (r = -0.38, p < 0.05). These findings show that the shape of the LPVC, represented by the constant k, predicts the degree of lung fibrosis and could be useful in the clinical assessment and follow-up of patients with ILD.

Exposure to biomass smoke and chronic airway disease in Mexican women. A case-control study

A case-control study was performed in women older than 40 yr of age to evaluate the risk of cooking with traditional wood stoves for chronic bronchitis and chronic airway obstruction (CAO). The subjects were recruited from patients attending a referral chest hospital in Mexico City. We selected 127 patients with chronic bronchitis or CAO, of which 63 had chronic bronchitis alone, 23 had CAO alone (FEV1 less than 75% of predicted), and 41 had both chronic bronchitis and CAO (cases). Four control groups were selected: 83 patients with pulmonary tuberculosis, 100 patients with interstitial lung diseases, 97 patients with ear, nose and throat ailments, and 95 healthy visitors to the hospital (controls). Exposure to wood smoke, assessed as any or none, and as hour-years (years of exposure multiplied by average hours of exposure per day) was significantly higher in cases than in controls. Crude odds ratios for wood smoke exposure were 3.9 (95% CI, 2.0 to 7.6) for chronic bronchitis only, 9.7 (95% CI, 3.7 to 27) for CAO plus chronic bronchitis, and 1.8 (95% CI, 0.7 to 4.7) for CAO only. Differences in exposure to wood smoke persisted after adjusting by stratification and logistic regression for age, income, education, smoking, place of residence, and place of birth. Risk of chronic bronchitis alone and chronic bronchitis with CAO increased linearly with hour-years of cooking with a wood stove; odds ratios for exposure to more than 200 hour-years compared with nonexposed were 15.0 (95% CI, 5.6 to 40) for chronic bronchitis only and 75 (95% CI, 18 to 306) for chronic bronchitis with CAO. The findings support a causal role of domestic wood smoke exposure in chronic bronchitis and chronic airflow obstruction.

The genetics of asthma

In this paper we have summarized the evidence for a genetic contribution to asthma as well as the recent advances in techniques for identifying the location and function of genes that cause complex diseases. We have also reviewed how these techniques have been applied to the study of asthma and allergy. It is likely that rapid additional advances will be made over the next several years. There are ongoing genome-wide searches to identify additional genes. An understanding of the genetic variation that predisposes people to asthma and the atopic diseases could open a variety of potential diagnostic and therapeutic avenues. Firstly, the identification of the specific mutations that alter the immune response could provide targets for gene therapy. However, in the short run this is unlikely because the risks and costs associated with gene therapy do not presently justify application to alleviate the relatively nonlethal manifestations of allergic diseases. The second potential avenue will be in the development of specific pharmacologic therapy. For example, if variants of the IL-4 gene with enhanced function or of the IFN-gamma gene that have deficient function are identified as causative factors, drug development could be directed toward specific modulators of their effects. However, it is possible that redundancy in the immune and inflammatory responses, coupled with the likelihood of multiple gene involvement, will make such targeting fruitless or dangerous. The third consequence of identifying genetic variants predisposing to asthma and allergy is the possibility of screening. This is perhaps the most likely beneficial outcome of the present search for atopy genes. Recent studies suggest that the clinical onset of atopic diseases can be modified by preventing exposure to cigarette smoke and highly allergenic proteins in the first few years of life (188). At present the power of such studies is limited by the inability to predict those at risk with any certainty. Genetic screening of children born to atopic parents will allow more precise identification of those carrying atopy genes, and this could allow a focused attempt at environmental modification. In the short run this will allow the design of much more powerful prospective studies of prophylaxis, and in the long run screening may prove an effective strategy for asthma prevention.

Endogenous nitric oxide influences acetylcholine-induced bronchovascular dilation in sheep

To test whether endogenous endothelial nitric oxide (NO) influences baseline bronchial vascular tone and mediates acetylcholine (ACh)-induced bronchial vascular dilation and/or modulates bronchoconstriction in ovine airways, we studied anesthetized ventilated open-chest sheep and measured bronchial blood flow (Qbr) and pulmonary resistance (RL). In six sheep we measured the response of Qbr and RL to the dose of ACh required to produce 50% of the maximal increase in Qbr at baseline during infusion of the NO synthase inhibitor NG-nitro-L-arginine (L-NNA; 10(-2) M). Infusion of L-NNA decreased both the baseline Qbr (28 +/- 13 to 8 +/- 2 ml/min, P < 0.01) and the change in Qbr (delta Qbr) from the baseline value (84 +/- 42 to 33 +/- 18 ml/min, P < 0.05). There was no difference in baseline RL or in the response of RL to ACh at any time. In another six sheep, phenylephrine (5 x 10(-6) to 5 x 10(-7) M) decreased baseline Qbr (22 +/- 6 to 10 +/- 3 ml/min, P < 0.05) but not delta Qbr (62 +/- 13 to 66 +/- 21 ml/min, not significant). Infusion of L-NNA in these sheep decreased the baseline Qbr to a similar extent (11 +/- 5 ml/min) and also decreased delta Qbr (42 +/- 16 ml/min, P < 0.05). We conclude that endogenous endothelial NO influences baseline vascular tone and ACh-induced vasodilation of the ovine bronchial vasculature but has no effect on baseline RL or ACh-induced bronchoconstriction.

Relation of smoking to immunoreactive endothelin in the bronchiolar epithelial cells

BACKGROUND

Endothelin is a potent bronchoconstrictor which appears to be important in asthma. To ascertain whether cigarette smoking is associated with any alteration in the proportion of bronchiolar epithelial cells which express endothelin immunoreactivity, the airways in the lungs of non-smokers and smokers were analysed. Since an increase in immunoreactivity has been found in the bronchial epithelial cells of asthmatic subjects, cigarette smokers with and without evidence of airway hyperresponsiveness were also selected.

METHODS

A point counting method which examined the proportion of endothelin immunoreactive epithelial cells in membranous and respiratory bronchioles was used.

RESULTS

Neither smoking itself nor evidence of airway hyperresponsiveness altered the percentage of endothelin immunoreactive epithelial cells in the membraneous and respiratory bronchioles.

CONCLUSIONS

Cigarette smoke does not induce endothelin production in bronchiolar epithelial cells, and the airway hyperresponsiveness seen in some patients with lung disease induced by cigarette smoking is not related to exaggerated endothelin production in epithelial cells.

Blood flow distribution to upper airway muscles

Radiolabeled (15-microns) microspheres were used to measure blood flow to upper airway muscles [alae nasi (AN), intrinsic laryngeal, tongue, cervical strap, and hyoid musculature], diaphragm (DI), and parasternals (PS) during spontaneous breathing in 24 anesthetized tracheotomized supine dogs. Six dogs were also studied while -28 +/- 3 (SE) cmH2O tracheal airway pressure was generated against an inspiratory resistance (IR) (upper airway bypassed). Blood flow to posterior cricoarytenoid muscle (PCA) [24.0 +/- 2.1 (SE) ml.min-1.100 g-1] was greater than that to DI (18.0 +/- 2.3 ml.min-1.100 g-1) and comparable to that to PS (21.4 +/- 2.9 ml.min-1.100 g-1). Blood flow per unit weight did not differ between AN, tongue muscles, laryngeal adductors, cervical strap muscles, and cricothyroid (CT). Average blood flow to these muscles was only 8.0 +/- 0.8 ml.min-1.100 g-1. With the exception of CT, blood flow to these upper airway muscles was less than that to DI and PCA. Relative to blood flow during spontaneous breathing, IR loading increased blood flow to AN by a factor of 7.5, to PCA by 3.4, to DI by 3.2 and to PS by 1.9. There was no change in blood flow in the other muscles during loading. Our results show that at rest blood flow to main glottic dilator (PCA) is similar to that to main inspiratory muscles. Furthermore, in response to an IR load, blood flow to PCA and AN increased by an equivalent or greater amount than that to DI.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo loads on airway smooth muscle: the role of noncontractile airway structures

The degree of airway smooth muscle contraction and shortening that occurs in vivo is modified by many factors, including those that influence the degree of muscle activation, the resting muscle length, and the loads against which the muscle contracts. Canine trachealis muscle will shorten up to 70% of starting length from optimal length in vitro but will only shorten by around 30% in vivo. This limitation of shortening may be a result of the muscle shortening against an elastic load such as could be applied by tracheal cartilage. Limitation of airway smooth muscle shortening in smaller airways may be the result of contraction against an elastic load, such as could be applied by lung parenchymal recoil. Measurement of the elastic loads applied by the tracheal cartilage to the trachealis muscle and by lung parenchymal recoil to smooth muscle of smaller airways were performed in canine preparations. In both experiments the calculated elastic loads applied by the cartilage and the parenchymal recoil explained in part the limitation of maximal active shortening and airway narrowing observed. We conclude that the elastic loads provided by surrounding structures are important in determining the degree of airway smooth muscle shortening and the resultant airway narrowing.

Aerosol pentamidine-induced bronchoconstriction. Predictive factors and preventive therapy

OBJECTIVE

To describe the frequency of aerosol pentamidine-induced bronchoconstriction, its relationship to non-specific airway responsiveness, and its response to preventive therapy using salbutamol, ipratropium bromide, or sodium cromoglycate.

METHODS

Consecutive HIV-infected individuals starting prophylactic AP were eligible if they had not been previously treated with this agent. Simple spirometry was performed before and 10 min after a single 60-mg dose given through an ultrasonic nebulizer. Methacholine challenge was performed in all subjects 24 h to four days after the initial AP dose. Subjects with a change in FEV1 (delta FEV1) greater than or equal to 10 percent decrease after the initial AP dose were restudied on three separate occasions (greater than 24 hours apart) after premedication with two puffs of salbutamol (200 micrograms), ipratropium bromide (40 micrograms), or sodium cromoglycate (2 mg), in random order.

RESULTS

Fifty-three subjects were studied. The median delta FEV1 after a single dose of AP was -7.0 percent (range: -47 percent, 1.8 percent). The delta FEV1 following AP was only partially predicted by the degree of nonspecific bronchial responsiveness as measured by a standard methacholine challenge. Age, current smoking, history of asthma, baseline FEV1, or a prior episode of PCP failed to predict the delta FEV1 following AP. Eighteen subjects (34 percent) had a delta FEV1 greater than or equal to 10 percent decrease (median: -17.0 percent). In these subjects, after premedication with salbutamol, ipratropium bromide, and sodium cromoglycate, the median delta FEV1 was 1.0, 0.8, and -9.6 percent, respectively.

CONCLUSION

Aerosol pentamidine produced a decrease in FEV1 greater than or equal to 10 percent in 34 percent of subjects. This was not accurately predicted by the methacholine response. The bronchoconstriction induced by AP was effectively prevented by either salbutamol or ipratropium, whereas cromoglycate was only partially effective.

Tracheal smooth muscle mechanics in vivo

We applied the technique of sonomicrometry to directly measure length changes of the trachealis muscle in vivo. Pairs of small 1-mm piezoelectric transducers were placed in parallel with the muscle fibers in the posterior tracheal wall in seven anesthetized dogs. Length changes were recorded during mechanical ventilation and during complete pressure-volume curves of the lung. The trachealis muscle showed spontaneous fluctuations in base-line length that disappeared after vagotomy. Before vagotomy passive pressure-length curves showed marked hysteresis and length changed by 18.5 +/- 13.2% (SD) resting length at functional residual capacity (LFRC) from FRC to total lung capacity (TLC) and by 28.2 +/- 16.2% LFRC from FRC to residual volume (RV). After vagotomy hysteresis decreased considerably and length now changed by 10.4 +/- 3.7% LFRC from FRC to TLC and by 32.5 +/- 14.6% LFRC from FRC to RV. Bilateral supramaximal vagal stimulation produced a mean maximal active shortening of 28.8 +/- 14.2% resting length at any lung volume (LR) and shortening decreased at lengths above FRC. The mean maximal velocity of shortening was 4.2 +/- 3.9% LR.S-1. We conclude that sonomicrometry may be used to record smooth muscle length in vivo. Vagal tone strongly influences passive length change. In vivo active shortening and velocity of shortening are less than in vitro, implying that there are significant loads impeding shortening in vivo.

Adult celiac sprue: changes in the pattern of clinical recognition

We report the clinical, laboratory, and pathological findings in a series of 52 consecutive patients with adult celiac sprue observed over a 20-year period. The frequency of that diagnosis increased from an average of 0.7 case/year during the period 1966-1975 to 5.8 cases/year during the period 1981-1985. Apart from two patients with dermatitis herpetiformis, nonclassical clinical presentations were observed in 16 of 50 (32%) patients overall and in 13 of 28 (46%) patients diagnosed since 1981. Diarrhea was the most common complaint leading to the diagnosis; since 1981, hematologic abnormalities warranted investigation in 38% of the patients. Decreased iron stores (88%), decreased red cell folate (82%), or both (74%), and abnormal radiographic studies of the small bowel (83%) were the most sensitive tests in the diagnostic investigation. We conclude that atypical or nonclassical presentations of adult celiac sprue, mostly with hematologic abnormalities, are not uncommon.

Differential diagnosis of bronchiolitis obliterans with organizing pneumonia and usual interstitial pneumonia: clinical, functional, and radiologic findings

To assess the role of chest radiography in the differential diagnosis of bronchiolitis obliterans organizing pneumonia (BOOP) and usual interstitial pneumonia (UIP), records of 34 patients with biopsy-proved BOOP (16 patients) or UIP (18 patients) were reviewed. Chest radiographs taken before biopsy were available in 26 patients, clinical information in 33, and pulmonary function data in 22. These data were reviewed independently, without knowledge of the pathologic diagnosis. The clinical symptoms of BOOP were similar to those of UIP, although the duration of symptoms was longer in UIP (P less than .05), and the prevalence of systemic symptoms was higher in BOOP (P less than .025). The physical findings were similar except that finger clubbing was more common in patients with UIP than in those with BOOP (P less than .01). There was no significant difference in lung volumes, flows, or diffusing capacity between BOOP and UIP. The chest radiograph showed distinguishing features between UIP and BOOP in 23 of 26 patients. The most characteristic radiologic finding in BOOP was the presence of patchy areas of air-space consolidation (eight of 11 patients).

A comparative trial of ranitidine 300 mg at night with ranitidine 150 mg twice daily in the treatment of duodenal and gastric ulcer

A multicenter double-blind comparative trial of oral ranitidine, 300 mg hs versus 150 mg bid, was conducted in 89 patients with duodenal ulcer (DU) and 54 with gastric ulcer (GU). Antacid tablets were prescribed prn. After 4 wk of treatment there were no statistically significant differences in the ulcer healing rates associated with the once daily (DU 86.4%, GU 62.5%) and the twice daily (DU 84.4%, GU 73.3%) regimens. Antacid consumption, by both DU and GU patients, was higher in the 150 mg bid group, but the differences did not achieve statistical significance. Further improvement in cumulative healing rates in response to both treatment regimens was observed following a second 4-wk treatment for those patients whose ulcers had failed to heal during the 1st month. Smoking adversely affected the rate of ulcer healing in DU patients, but had no significant effect on GU healing. No serious adverse effects or biochemical abnormalities were observed. Ranitidine 300 mg hs appears to be equally safe and effective as the standard regimen of 150 mg bid in the short-term treatment of uncomplicated gastroduodenal ulcer.

Impaired renal acidification in alcoholic liver disease

The prevalence of impaired renal acidification in alcoholic liver disease and its relationship to clinical and biochemical features were evaluated during a one-year period in a 60-bed liver unit. No cases of overt renal tubular acidosis (RTA) were found; all of 12 patients with low serum bicarbonate values and normal anion gap proved to have chronic respiratory alkalosis. However, there was a 57% prevalence of incomplete distal RTA in 42 patients who were tested with an acid load. Subjects with RTA had higher serum bilirubin levels (5.3 +/- 6.1 v 2.1 +/- 2.7 mg/dL) and lower prothrombin times (45% +/- 22% v 64% +/- 20%). Urinary pH correlated directly with serum bilirubin levels (r = +.38) and inversely with prothrombin times (r = -.46). The frequency of ascites and encephalopathy did not differ notably between the two groups of patients. No pathogenetic relation was observed with avid sodium retention, decreased excretion of nonreabsorbable anions, and elevated urinary excretion of bile acids. Therefore, we conclude that impaired renal acidification in alcoholic liver disease may be a sign of liver cell failure since it is more frequently observed in patients with a greater degree of liver dysfunction.

Bile-duct cyst with cystlithiasis: a case report

Cystic dilatation of the biliary tree is an uncommon congenital condition, most often discovered in infancy. It should be suspected in an adult who has a history, over a long period, of intermittent pain in the right upper quadrant, episodes of jaundice or cholangitis, or both, and has a palpable mass in the right hypochondrium. Ultrasonography and especially endoscopic retrograde cholangiopancreatography allow the biliary cyst to be diagnosed preoperatively more often than previously. The authors describe the case of a 60-year-old woman with congenital cystic dilatation of extra- and intrahepatic bile ducts with cystlithiasis that followed an unusual course. Of the various theories of causation, Babbitt 's is now the most widely accepted, especially since the advent of endoscopic retrograde cholangiopancreatography. The presence of stones is an uncommon and late complication. The treatment is surgical, excision of the biliary cysts being the treatment of choice; however, Roux-en-Y choledochocystojejunostomy is performed when excision is technically impossible.

Serum-ascites albumin concentration gradient: a physiologic approach to the differential diagnosis of ascites

Serum-ascites albumin concentration gradient, a parameter of oncotic pressure gradient reflecting presence or absence of portal hypertension, was compared with the usual parameters of ascitic fluid analysis in the differential diagnosis of ascites. Twenty-nine patients with liver disease and 15 patients with malignant neoplasm were prospectively studied. The group with malignant neoplasm showed higher ascitic fluid total protein level (3.70 +/- 1.28 vs. 1.66 +/- 1.20 g/dl), ascites to serum ratio of total protein level (0.58 +/- 0.14 vs. 0.26 +/- 0.14), ascitic fluid lactic dehydrogenase level (756 +/- 693 vs. 151 +/- 125 U/L), ascites to serum ratio of lactic dehydrogenase level (1.13 +/- 0.79 vs. 0.35 +/- 0.22), and lower serum-ascites albumin gradient (0.72 +/- 0.30 vs. 1.85 +/- 0.45) (p less than 0.001 for all parameters). Results of the serum-ascites albumin gradient overlapped the least between the two groups: all but 1 patient with malignant ascites while only 1 patient with liver disease had a gradient lower than 1.1. We conclude that the serum-ascites albumin gradient offers the best diagnostic discrimination between ascites caused by liver disease and ascites caused by a neoplasm.

Effect of ranitidine on healing of peptic ulcer: a 2-month study

A multicenter trial of oral ranitidine 150 mg bid was conducted in 41 patients with duodenal and 30 with gastric ulcers. Patients were randomly allocated in double-blind fashion to 4 wk treatment with either ranitidine or placebo, after which all unhealed patients were given 4 wk on the active drug without breaking the original allocation code. After 4 wk of treatment the healing rate associated with ranitidine was significantly superior to that of placebo in both duodenal and gastric ulcer patients. Further improvement in cumulative healing rates was observed after the 2nd month of the study. After the allocation code was broken and all patients had had the opportunity of up to 8 wk on the active drug, there remained only a single unhealed pyloric ulcer. No serious adverse effects or biochemical abnormalities were observed. Ranitidine is a potent and well-tolerated H2 antagonist. Therapy for 4 or 8 wk is highly effective in the treatment of uncomplicated gastroduodenal ulcer.

Double-blind, controlled trial of propylthiouracil in patients with severe acute alcoholic hepatitis

Sixty-seven patients entered a double-blind, controlled trial to evaluate the efficacy of propylthiouracil treatment in severe alcoholic hepatitis. Twenty-three percent (7 of 31) given propylthiouracil and 19% (7 of 36) given placebo died during the 6-wk study. Propylthiouracil treatment did not reduce the frequency and incidence of complications in alcoholic hepatitis, but induced hypothyroidism in 4 patients. Treatment produced no beneficial effect on any of the hepatic biochemical tests. We were unable to show any beneficial effect of propylthiouracil treatment on morbidity and mortality in patients with severe acute alcoholic hepatitis.

The effect of H2-blocking agents on systemic anaphylaxis in guinea pigs

Theoretically, histamine H2 antagonists could aggravate allergic bronchoconstriction (1) by increasing mediator release, and (2) by blocking histamine-induced bronchodilatation. We measured dynamic compliance, subdivisions of lung volume, and mortality in immunized guinea pigs after parenteral administration of antigen, with and without pretreatment with the H2-blocking agents cimetidine and metiamide. Administration of antigen caused significant mortality as well as decreases in dynamic compliance, total lung capacity, and vital capacity and increases in functional residual capacity. The prior administration of cimetidine or metiamide did not protect against or enhance these effects of antigen challenge.

Definition of a conjugation of dysfunction in Gilbert's syndrome: studies of the handling of bilirubin loads and of the pattern of bilirubin conjugates secreted in bile

1. Intravenous doses of bilirubin (3.4 mumol/kg) were given to normal subjects and patients with Gilbert's syndrome. Both groups displayed an identical initial disappearance of a substantial proportion of the bilirubin but, late in time, the Gilbert's patients exhibited reduced clearance with a sustained elevation of the plasma bilirubin and no reflux into the plasma space of conjugated bilirubin. Increasing the dose in normal subjects (by factors of 3 and 6) failed to reproduce the response found in the Gilbert's patients. 2. In the the bile-containing duodenal aspirates of Gilbert's patients the average proportion of bilirubin found as bilirubin diglucuronide was 68% (normal 88%) and of bilirubin monoglucuronide, 23% (normal 7%). Both differences were significant at the P less than 0.001 level. In the Gilbert's patients restriction of caloric intake to 1569 kJ/day for 2 days characteristically raised the serum bilirbuin with no modification of the biliary pigment pattern; phenobarbital (180 mg/day for 2 weeks) decreased the plasma bilirubin to the normal range with, concomitantly, a reversion of the biliary pigment pattern towards normal. 3. We conclude that there is no hepatic uptake defect in Gilbert's syndrome but that there is decreased activity in the conjugation process underlying the addition of the second glucuronic acid moiety to bilirubin, to form bilirubin diglucuronide.

Nonvisualization of the gallbladder by 99mTc-HIDA cholescintigraphy as evidence of cholecystitis

Cholescintigraphy with N-substituted iminodiacetic acid (HIDA) labelled with technetium-99m is a new noninvasive technique for evaluation of the hepatobiliary system. The significance of nonvisualization of the gallbladder by this method in comparison with standard radiologic examinations was studied. In 43 healthy subjects the gallbladder was visualized by the two methods. By contrast, all 27 patients in whom the gallbladder was not visualized by cholescintigraphy had cholecystitis. When visualization failed to occur, a repeat cholescintigraphic study after an injection of cholecystokinin demonstrated the status of the cystic duct. Visualization excludes cystic duct obstruction and acute cholecystitis, whereas persistent nonvisualization indicates cystic duct obstruction.