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Biomedical subjects

R W Chapman

Publications and source records attributed to R W Chapman.

At least 163 records · Page 9Linked to original sources
PubMed1988

Expression of HLA-DR antigens on bile duct epithelium in primary sclerosing cholangitis.

The expression of HLA class I (HLA-A, B, C) and class II (HLA-DR) antigens on the biliary epithelium of 10 patients (nine men) with primary sclerosing cholangitis (PSC) was investigated using an immunoperoxidase technique on cryostat sections. Five patients were staged as grade II and five grade III on hepatic histology. None were cirrhotic. as grade II and five grade III on hepatic histology. None were cirrhotic. Controls were nine patients with primary biliary cirrhosis (PBC), five with extra hepatic biliary obstruction, 15 with other forms of chronic liver disease and six with normal livers. Bile ducts from the normal subjects and patients with chronic liver disease did not express HLA-DR antigens. In contrast, all 10 of the PSC biopsies showed varying degrees of HLA-DR staining of the biliary epithelium. Expression of DR antigens was also found on the bile ducts of all five patients with extra hepatic biliary obstruction and in six of nine patients with PBC. Expression of HLA class I antigens was seen on the biliary epithelium of all the biopsies examined. Increased numbers of helper and suppressor T-cells were seen in the portal tracts of all the PSC patients. This study has confirmed that aberrant expression of HLA-DR may occur on the biliary epithelium of some, but not all, patients with PBC. In addition, the study has shown that aberrant expression of HLA-DR always occurs in PCS at an early stage of histological liver damage. While this may be important in the pathogenesis of PSC, the aberrant expression in extra hepatic biliary obstruction suggests that it may be a secondary phenomenon.

Adult↗
PubMed1988

Association of small intestinal diverticulosis with chronic pancreatitis leading to severe malabsorption. Report of three cases.

Three cases of chronic pancreatitis occurring in patients with small intestinal diverticulosis and bacterial overgrowth are reported. In two of the cases, pancreatic supplements were therapeutically beneficial (the third being unable to tolerate them). Two of the patients also developed diverticular perforation. The possible nature of the association between small intestinal diverticulosis and chronic pancreatitis is discussed.

Aged↗
PubMed1988

Central nervous system control of airway tone in guinea pigs: the role of histamine.

The central nervous system (CNS) plays an important role in the reflex control of bronchomotor tone, but the relevant neurotransmitters and neuromodulators have not been identified. In this study we have investigated the effect of histamine. Anesthetized male guinea pigs were prepared with a chronically implanted intracerebroventricular (icv) cannula and instrumented for the measurement of pulmonary resistance (RL), dynamic lung compliance (Cdyn), tidal volume (VT), respiratory rate (f), blood pressure (BP), and heart rate (HR). Administration of histamine (2-30 micrograms) icv caused a significant (P less than 0.05) reduction of Cdyn with no change in RL, VT, and f. At a dose of 100 micrograms icv, histamine caused an increase in RL (202 +/- 78%), a reduction of Cdyn (77 +/- 9%), an increase in f (181 +/- 64%), and a reduction of VT (53 +/- 18%). There were no changes in BP and HR after 100 micrograms of icv histamine. In contrast, intravenous administration of histamine (0.1-2 micrograms/kg) caused a dose-dependent decrease in Cdyn and increase in RL that was associated with tachypnea at each bronchoconstrictor dose. Intravenous histamine (2 micrograms/kg) produced a fall in BP and an increase in HR. The bronchoconstrictor responses to icv histamine were completely blocked by vagotomy and significantly reduced by atropine (0.1 mg/kg iv), whereas vagotomy and atropine did not block the bronchospasm due to intravenous histamine. Additional studies indicated that the pulmonary responses due to icv histamine (100 micrograms) were blocked by pretreatment with the H1-antagonist chlorpheniramine (1 and 10 micrograms, icv). These data indicate that histamine may serve a CNS neurotransmitter function in reflex bronchoconstriction in guinea pigs.

Airway Resistance↗
PubMed1988

Antibronchoconstrictor activity of the intracellular calcium antagonist HA 1004 in guinea pigs.

HA 1004 is a calcium antagonist vasodilator that inhibits contraction in vascular smooth muscle and lowers arterial blood pressure. The effects of HA 1004 on guinea pig airway smooth muscle contraction were compared to the effects of the calcium antagonists, verapamil and nifedipine and the bronchodilator, albuterol. In vitro, HA 1004, verapamil, nifedipine and albuterol inhibited Ca2+-induced contractions of the depolarized guinea pig trachea. HA 1004 and albuterol also relaxed the basal tracheal tone, whereas verapamil and nifedipine were inactive. The bronchorelaxant activity of HA 1004 was not blocked by propranolol. In vivo, intravenous administration of HA 1004, verapamil, nifedipine and albuterol effectively blocked bronchoconstriction induced by intravenous histamine and methacholine. HA 1004 also reversed a histamine-induced bronchospasm, as did albuterol, verapamil and nifedipine. Intratracheal administration of HA 1004 and albuterol inhibited histamine-induced bronchoconstriction without effecting blood pressure, whereas intratracheal administration of verapamil and nifedipine caused a significant reduction of blood pressure at their pulmonary active doses. These results show that HA 1004 has the ability to relax airway smooth muscle, inhibit contractile responses in the guinea pig airways, and there is separation of its cardiovascular and pulmonary effects when HA 1004 is administered directly to the lungs. The results are discussed in terms of the regulatory enzymes and sources of calcium that are involved in airway smooth muscle contraction.

Animals↗
PubMed1988

Antiallergy activity of Sch 37224, a new inhibitor of leukotriene formation.

Sulfidopeptide leukotrienes (LTs) C4, D4 and E4 are important mediators in the pathophysiology of bronchial asthma. Sch 37224, 1-(1,2-dihydro-4-hydroxy-2-oxo-1-phenyl-1,8-naphthyridin-3-yl) pyrrolidinium, hydroxide inner salt, has been found to inhibit the formation of these autocoids. Although Sch 37224 did not inhibit 5-lipoxygenase, cyclooxygenase or phospholipase A2, it inhibited LTD4 and thromboxane B2 release by anaphylactic guinea pig lung (IC40 = 3.9 and 1.9 microM, respectively). At 5 microM Sch 37224 also inhibited superoxide anion radical generation from activated human polymorphonuclear neutrophilic leukocytes. When administered p.o. to guinea pigs, Sch 37224 decreased a LT-mediated allergic bronchospasm (ED40 = 1.1 mg/kg) for 6 hr and did not exhibit tolerance. In addition to its activities in allergen-induced bronchospasm in guinea pigs, Sch 37224 also inhibited hyperventilation-induced bronchospasm in guinea pigs at 0.5 to 5 mg/kg and anaphylactic bronchospasm in rats at 0.1 to 10 mg/kg. Sch 37224 was weak or ineffective as an antagonist of histamine, methacholine, serotonin, LTC4 or platelet activating factor induced bronchospasms in guinea pigs. Also, Sch 37224 was not a bronchodilator or calcium influx blocker and had only weak relaxant activity on guinea pig trachea in vitro (IC40 = 51 microM). Sch 37224 is, therefore, a potential antiallergic agent that inhibits LT release. It is p.o. effective in animal models of allergic and nonallergic-mediated bronchospasms.

Animals↗
PubMed1988

Early postoperative endoscopic sphincterotomy for retained biliary stones.

Endoscopic sphincterotomy was attempted on 18 patients with retained biliary stones. Endoscopy was performed within 2 weeks of the operation in 13 patients and within 3 weeks in 5 patients. A T-tube was present in 14 patients and 6 patients had multiple stones. Sphincterotomy and complete duct clearance was achieved in 17 patients (94%) and a complication (haemorrhage) occurred in one patient (6%).

Adult↗
PubMed1987

Oesophageal varices associated with busulphan-thioguanine combination therapy for chronic myeloid leukaemia.

5 patients receiving continuous busulphan and 6-thioguanine for chronic myeloid leukaemia (CML) were found to have oesophageal varices associated with abnormal liver function tests. 3 of these cases presented with gastrointestinal haemorrhage and 1 patient died. The 2 other cases had varices discovered at endoscopy. Nodular regenerative hyperplasia (NRH) of the liver was identified as the cause of portal hypertension in the 4 patients on whom liver biopsies were done. The administration of busulphan and thioguanine in combination is likely to be associated with the development of NRH, with portal hypertension and oesophageal varices occurring in a substantial proportion of cases.

Adult↗
PubMed1987

Antiallergic activity of loratadine, a non-sedating antihistamine.

Loratadine is a new non-sedating antihistamine. The present studies compared loratadine and terfenadine, another non-sedating antihistamine, for their ability to inhibit the bronchial response to histamine and other autacoids which have been implicated as contributing to the symptoms of an allergic reaction. In addition, the two antihistamines were evaluated in models of immunologically mediated allergic reactions. Loratadine is a more potent inhibitor of histamine-induced bronchospasm in guinea pigs than is terfenadine. Both antihistamines exhibit marked antiserotonin activity at doses 10 times their antihistamine ED50 values. In contrast, loratadine and terfenadine produce little or no inhibition of the bronchial responses to methacholine, leukotriene C4 or platelet-activating factor. An allergic bronchospasm in guinea pigs is inhibited by loratadine (ED50 = 0.40 mg/kg, p.o.) and terfenadine (ED50 = 1.7 mg/kg, p.o.). The bronchospasm associated with allergic anaphylaxis in rats is significantly inhibited by 10 mg/kg, p.o. loratadine and 30 mg/kg, p.o. terfenadine. Loratadine exhibits antiallergy activity in vitro. At micromolar concentrations, loratadine inhibits the release of histamine from Con A and A23187-stimulated rat peritoneal mast cells and the release of histamine and leukotriene C4 from a Con A-stimulated cloned murine mast cell line.

Animals↗
PubMed1987

Carcinoid tumour of the ampulla of Vater presenting as acute pancreatitis.

The first report of a carcinoid tumour of the ampulla of Vater causing acute pancreatitis is presented. The pancreatitis resulted from ampullary obstruction and diversion of the bile through the pancreas. Endoscopic retrograde cholangiopancreatography established the correct diagnosis, making this the first occasion in which a carcinoid tumour of the ampulla of Vater has been correctly diagnosed before surgery.

Ampulla of Vater↗
PubMed1987

Role of endogenous opioids on ventilation and chemical control of breathing in pentobarbitone-anesthetized rats.

To investigate the role of endogenous opioids on ventilatory control in pentobarbitone-anesthetized rats, the opioid antagonists naloxone and naltrexone were studied for their effects on ventilation, arterial blood gases and on ventilatory responses to hypoxia and carbon dioxide. In animals breathing room air, intravenous administration of naloxone and naltrexone (4 and 10 mg/kg) caused a dose-related increase in tidal volume, respiratory rate and minute volume. These ventilatory responses were rapid in onset and were associated with a decrease in arterial PaCO2, an increase in arterial pH and an increase in arterial PaO2. Intravenous naloxone (4 mg/kg) antagonized the increase in PaCO2 and decrease in arterial pH induced by the administration of morphine (3 mg/kg, i.v.). In animals breathing 100% O2, intravenous administration of naloxone and naltrexone (4 and 10 mg/kg) did not stimulate ventilation. Furthermore, intracerebroventricular administration of naloxone (15 and 150 micrograms) had no measurable effect on ventilation. Ventilatory responses to both hypoxia and carbon dioxide were not augmented by intravenous naloxone (4 mg/kg) and naltrexone (4 and 10 mg/kg). In fact, the increase in respiratory rate due to hypoxia was significantly (p less than 0.05) reduced by naltrexone (10 mg/kg, i.v.). In conclusion, our results demonstrate that naloxone and naltrexone caused hyperventilation in pentobarbitone-anesthetized rats. This effect was probably triggered by stimulation of the peripheral arterial chemoreceptors and did not involve mechanisms directly associated with the central nervous system. However, endogenous opioids were not involved in the chemical control of breathing in pentobarbitone-anesthetized rats since ventilatory responses to hypoxia and carbon dioxide were not changed by administration of these opioid antagonists.

Anesthesia↗
PubMed1986

Serum autoantibodies, ulcerative colitis and primary sclerosing cholangitis.

The aetiology of primary sclerosing cholangitis is unknown, but it is closely associated with ulcerative colitis. Serum anticolon antibodies, crossreacting with portal tracts, have been reported in patients with ulcerative colitis but no studies have been carried out in primary sclerosing cholangitis. The frequency of serum anticolon antibodies and portal tract antibodies have been measured in 24 patients with primary sclerosing cholangitis and ulcerative colitis; 15 patients with primary sclerosing cholangitis without ulcerative colitis; 77 patients without primary sclerosing cholangitis: 25 patients with Crohn's colitis; 10 patients with primary biliary cirrhosis; 22 patients with extrahepatic biliary obstruction and 20 normal controls. Serum anticolon and portal tract antibodies were detected using immunoperoxidase techniques on normal colon and obstructed human liver. Tissue typing was undertaken using a standard microcytotoxicity technique. The frequency of anticolon antibodies was markedly increased in primary sclerosing cholangitis patients with ulcerative colitis (62.5%) compared with patients with ulcerative colitis (17%) and Crohn's colitis (16%) (chi 2 = 17.9; p less than 0.001). The antibodies were almost entirely of IgG and IgA classes in all groups. Anticolon antibodies were not found in sera from any other group. Sera from eight of 15 patients with primary sclerosing cholangitis, ulcerative colitis and anticolon antibody reacted with portal tracts of human obstructed liver. This reaction was also seen in four of nine patients with ulcerative colitis and primary sclerosing cholangitis and in three of 15 patients with primary sclerosing cholangitis alone. Portal tract antibody was of IgG class and was not present in sera from any other groups. Unlike anticolon antibody, there was a close relationship between HLA-B8 phenotype and the portal tract antibody (p<0.02; chi 2 = 6.04). Absorption studies confirmed that the anticolon antibody is distinct from portal tract antibody.

Autoantibodies↗
PubMed1986

Controlled trial of intravenous metronidazole as an adjunct to corticosteroids in severe ulcerative colitis.

A prospective double blind controlled trial was undertaken to examine the role of metronidazole as an adjunct to corticosteroids in the management of severe ulcerative colitis. Thirty nine patients with severe ulcerative colitis were randomised on admission to hospital to receive either intravenous metronidazole 500 mg eight hourly (19 patients) or an identical intravenous placebo (20 patients). The two groups were similar with respect to age, sex, and the extent of colitis. In addition all patients received a standard intravenous regimen consisting of methyl prednisolone 16 mg six hourly and parenteral nutrition together with a twice daily hydrocortisone 100 mg enema. Treatment was continued for five days when the patients were formally assessed. Fourteen of 19 patients (74%) receiving metronidazole and 14/20 (70%) receiving placebo were substantially improved, or in remission at the end of five days. Five patients treated with metronidazole and six with placebo had no improvement and all proceeded to urgent colectomy with no operative mortality. There were three late deaths, one in the metronidazole and two in the placebo group. These results do not support the routine use of intravenous metronidazole in the treatment of severe ulcerative colitis.

Adolescent↗
PubMed1985

Bronchodilator and antiallergy activity of forskolin.

Forskolin is a diterpene from the roots of Coleus forskohli which directly activates the adenylate cyclase and raises cyclic AMP levels in a variety of tissues. Forskolin was studied for its effects on the tone of airway smooth muscle and the immunologic release of leukotrienes and histamine. The bronchospasm induced by inhaled antigen in sensitized guinea pigs was prevented in a dose-related fashion by the intravenous (i.v.) or intratracheal administration of forskolin. Forskolin was more potent than aminophylline and less potent than salbutamol. There was no evidence that forskolin would potentiate the in vivo bronchodilator effects of either salbutamol or aminophylline. Forskolin was approximately 100 times more potent than aminophylline by the i.v. and intratracheal routes to reverse an established allergic bronchospasm. Forskolin given intratracheally also inhibited the bronchospasm to i.v. histamine, with a short duration of action. In vitro forskolin (less than 1 microM) inhibited contractions of lung parenchyma provoked by histamine, LTC4 or antigen. Forskolin (1 microM) also inhibited the immunologically stimulated release of LTD4 and histamine from sensitized guinea pig lung. These studies show that forskolin shares with other agents that elevate cyclic AMP levels the ability to relax airway smooth muscle and inhibit mediator release in vitro and elicit a bronchodilation in vivo.

Animals↗
PubMed1985

Effect of oral dioctyl sodium sulfosuccinate on intake-output studies of human small and large intestine.

Dioctyl sodium sulfosuccinate (DSS) is an anionic detergent that is used widely as a laxative and promoted as a stool softener. Although many anecdotal reports attest to the laxative and stool softening efficacy of DSS, no controlled trials have been performed to document the effect of DSS on small or large bowel function in humans. We have compared, therefore, the effects of 100 mg of DSS three times daily (the maximum recommended dose) with placebo in a randomized, single blind, crossover study in two groups of subjects. First, 6 healthy ileostomates were studied while they ate a constant diet for 8 days. Dioctyl sodium sulfosuccinate administered for 4 days did not increase the daily ileal output of carbohydrate, total fatty acids, bile acids, nitrogen, or water. Cholesterol excretion was decreased while taking DSS (p less than 0.05). Second, 6 healthy volunteers were studied while eating a constant diet of 20 g of fiber plus 30 radiopaque markers daily so that mean daily transit time could be measured. After equilibration, a 7-day collection of stool was weighed and lyophylized to measure fecal water. Dioctyl sodium sulfosuccinate had no effect on stool weight, stool frequency, stool water, or mean transit time. We conclude that 300 mg/day of DSS does not increase ileal or colonic output of solids or water in healthy human subjects.

Administration, Oral↗
PubMed1985

Effect of propranolol on pulmonary function and bronchoconstrictor responsiveness in guinea pigs and rats.

The beta-blocker propranolol was studied for its effects on basal pulmonary functions and on bronchoconstrictor responses to methacholine and histamine in mechanically ventilated guinea pigs and rats. Using doses that blocked the antibronchoconstrictor (bronchodilator) effects of the beta 2-agonist salbutamol, propranolol had no measurable effect on basal airway resistance and dynamic lung compliance in both guinea pigs and rats. However, bronchoconstrictor responses to methacholine and histamine were augmented by propranolol in guinea pigs. In contrast, propranolol did not change bronchoconstrictor responses to methacholine in rats. These results are discussed in terms of the functional role of pulmonary beta-receptors in guinea pigs and rats.

Airway Resistance↗
PubMed1985

Absorption of starch by healthy ileostomates: effect of transit time and of carbohydrate load.

Recently, breath hydrogen studies and intubation techniques have indicated that in excess of 10% of starch in normal foods may be malabsorbed in the small intestine and enter the colon. We evaluated starch absorption in healthy subjects with ileostomy. First, unabsorbed starch was quantified in ileostomy effluent from six ileostomates who ingested constant diets of wheat and potato starch for four days. Daily unabsorbed starch ranged from 1.3% to 5.0% of total ingested starch. Second, starch from a radiolabeled solid meal containing 50 g potato starch was measured under control conditions and after altering transit time with either loperamide, or magnesium citrate. Loperamide significantly decreased the amount of unabsorbed starch in all six ileostomates (p less than 0.05), while magnesium citrate significantly increased starch malabsorption in all six subjects (p less than 0.05). Third, starch absorption was measured after single solid meals containing 25, 50, 75, and 100 g potato starch. There was a linear relationship between starch input and output. Mean output expressed as a percent of input remained constant. We conclude that the degree of starch malabsorption by the small intestine of ileostomates may be less than that estimated by indirect methods in intact humans. The amount of unabsorbed starch is directly related to the quantity ingested and to the small intestinal transit time.

Adult↗
PubMed1985

Histological features of sclerosing cholangitis in patients with chronic ulcerative colitis.

Primary sclerosing cholangitis was diagnosed radiologically in 16 of 681 patients (2.2%) with chronic ulcerative colitis in a follow up study at the gastroenterology unit in Oxford. On the basis of established histological criteria, the liver biopsy was considered diagnostic in only half of the cases. The histological findings in these cases were therefore reassessed to determine whether the accuracy of biopsy diagnosis could be improved. The most common specific histological feature was periductal concentric fibrosis of small interlobular bile ducts, even in the absence of inflammation. Other common features were bile ductular proliferation associated with diminution or absence of interlobular bile ducts. Degeneration of bile duct epithelium and diffuse infiltration of portal tracts by mononuclear cells and polymorphonuclear leucocytes were accompanying features. Piecemeal necrosis without rosette formation was found in about half the biopsies. When all these features were considered together a biopsy diagnosis of primary sclerosing cholangitis was established in 14 of 16 cases.

Adult↗