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Biomedical subjects

H D Ritchie

Publications and source records attributed to H D Ritchie.

12 recordsLinked to original sources
PubMed1987

Effects of using sires selected for yearling weight and crossbreeding with beef and dairy breeds: birth and weaning traits.

Data consisting of 948 calf records collected from 1978 to 1982 were analyzed to determine the effects of breeding methods used to improve commercial herds genetically on birth and weaning traits. Four distinct groups were used in the project: Group 1 (G1), an unselected, random mating Hereford control line; Group 2 (G2), a Hereford group using sires selected for yearling growth; Group 3 (G3), a rotational cross with Angus, Hereford, Charolais and Simmental breeds; and Group 4 (G4), a rotational cross with Angus, Hereford, Simmental and Holstein-Friesian breeds. Traits analyzed were birth weight (BW), calving difficulty (CD), percent assisted births (%AB), percent born alive (%BL), preweaning average daily gain (PWDG), relative growth rate (RGR), weaning weight (WWT) and percent weaned (%WND). The use of high yearling weight sires in G2 increased calf size (P less than .01) at birth and weaning by 8.9 and 28.1 kg, respectively, along with increased CD (P less than .01). Use of rotational crossbreeding systems increased calf size and growth from birth to weaning (P less than .01), but decreased CD and %AB (P less than .01) by .17 units and 13.5%, respectively. Including Holstein-Friesian in G4 resulted in further increases in preweaning growth (P less than .01) and calving ease was improved without affecting BWT compared with G3.

Animals↗
PubMed1977

The gastrointestinal myoelectric response to 13-Nle-motilin infusion during interdigestive and digestive states in the conscious dog.

Gastrointestinal myoelectric activity was studied in three conscious fasted dogs with electrodes surgically implanted in the stomach and small intestine, during separate and combined intravenous infusions of 13-norleucine motilin (13-nle-motilin) and pentagastrin (PG). Basal recordings confirmed the presence of regular interdigestive myoelectric complexes (MC's). 13-nle-motilin infusion below 50 ng/kg-h was without effect: higher doses up to 400 ng/kg-h resulted in the interpolation of one or more MC's in the spontaneous sequence. The rate of aboral transit of 13-nle-molitin-induced MC's did not differ significantly from that of spontaneous MC's. When MC's were abolished by feeding or PG infusion, simultaneous 13-nle-motilin administration was without effect on spike activity, but slightly attenuated the accelerating effect of gastrin on the gastric pacemaker frequency. The myoelectric events triggered by 13-nle-motilin suggest that in the conscious dog the polypeptide may not act directly on the smooth muscle cell, as it does in vitro, but through an extra-enteric neural control mechanism which is uncoupled by gastrin.

Aminocaproates↗
PubMed1976

Metabolism of histamine in secreting and isolated canine stomach.

Total 14C activity in juice secreted by gastric pouches of six dogs and seven isolated canine stomachs was determined in response to intravenous and intra-arterial infusions of histamine and [14C]histamine. The proportions of 14C attributable to histamine, Nalpha-methylhistamine (NalphaMeH), Nalpha,Nalpha-dimethylhistamine (NalphaNalphaMe2H), N-telle-methylhistamine (NtauMeH), imidazole acetic acid (ImAA), N-methylimidazole acetic acid (NtauMeImAA), acetylhistamine (AcH), and histaminol (HOH) were defined using thin-layer chromatography. Similar estimates were made at the end of infusions on blood, gastric mucosa, and gastric muscle. Methylation was the major, or sole, route of metabolism of histamine in the gastric mucosa, and the major product was inactive NtauMeH. Small quantities of the active NalphaMe derivatives, particularly NalphaNalphaMe2H, were identified in both the juice and mucosa. Little or no ImAA, NtauMeImAA, AcH, and HOH were present in juice from isolated stomachs while they did occur in the juice from intact dogs, demonstrating they are extragastric metabolites of histamine. A major mucosal function of methylation of histamine is inactivation, although NalphaMe derivatives formed may play a role in the secretagogue action of histamine.

Acetates↗
PubMed1976

Motilin-induced electrical activity in the canine gastrointestinal tract.

Myoelectric activity induced by a synthetic analogue of the duodenal polypeptide motilin, was studied in isolated vascular-perfused canine duodenum and stomach, and in conscious dogs with serosal electrodes implanted in the stomach and the small intestine. In the isolated preparation, the duodenum was found to be four times as sensitive as the antrum to the polypeptide, showing a dose-dependent increase in spike activity within two minutes after administration of the polypeptide. By contrast, in the conscious fasted animal, the only response to motilin, above a threshold dose, was the interpolation of a premature migrating myoelectric complex in the spontaneous interdigestive sequence, appearing fifteen to twenty minutes after the start of infusion. Since the essential difference between the ex vivo and the intact intestine was the preservation of efferent and afferent nervous connections in the latter, it seems that in the conscious animal, the response to exogenous motilin is modulated by the innervation of the intestine, or, alternatively, motilin interacts with the centre controlling the pattern of motor activity in the small intestine rather than directly with smooth muscle. The latter hypothesis is supported by the observation that motilin had no effect on the motor activity of the small intestine during the infusion of pentagastrin which abolishes spontaneous migrating myoelectric complexes.

Action Potentials↗
PubMed1976

Effects of 13-nle-motilin on the electrical and mechanical activity of the isolated perfused canine stomach and duodenum.

Synthetic 13-norleucine-motilin (13-nle-motilin), structural and biological analogue of the naturally-occurring duodenal polypeptide, motilin, is known to stimulate antral and duodenal motor activity in vitro, but delays gastric emptying in man. In this study the direct actions of the synthetic polypeptide on myoelectrical activity and intraluminal pressure have been studied in the isolated vascular-perfused canine stomach and duodenum. 13-nle-motilin increased intraluminal pressure in the pylorus and duodenum, and dose-response analysis showed the duodenum to be twice as sensitive as the pylorus to the polypeptide. Pressure changes in the antrum were small and not dose-related, but, whereas the basic electrical rhythm in the duodenum was not altered, slow wave frequency, rhythm, and propagation in the antrum were disturbed. Electronic analysis of the duodenal spike increase which accompanied pressure rises demonstrated correlations between increases in spikes, intraluminal pressure, and dose. These results show that the direct effect of the polypeptide on adjacent organs may explain the combination of increased motor activity with delayed gastric emptying as a consequence of disturbance in the co-ordination between antrum, pylorus, and duodenum.

Animals↗
PubMed1975

How should the common bile duct be explored?

An attempt has been made to find which of 3 operations currently in use for exploring the bile ducts gave the best clinical results. For this purpose 3 series of consecutive patients treated at The London Hospital over a 12-year period have been studied retrospectively. The operations used were as follows: (1) conventional supraduodenal choledochotomy; (2) transduodenal biliary sphincterotomy; and (3) a combined approach. The mortality in the supraduodenal series was 4 (4%) of 101 patients and in the transduodenal series 2 (2.4%) of 82 patients. Both routes were used in 26 patients, of whom 2 (7.7%) died. Early complications were commoner after choledochotomy than after biliary sphincterotomy, but when both procedures were combined the incidence was higher still. Late complications were also more frequent after both the supraduodenal and the combined approach, residual or recurrent stones and cholangitis being 6 times more common than after sphincterotomy alone. Postexploratory cholangiography, however, was not used routinly in the supraduodenal series and might conceivably have reduced this factor further, but not below 3. Stenosis occurred in one patient after choledochotomy and in one patient after the combined operation but not after sphincterotomy alone. In this study, therefore, transduodenal biliary sphincterotomy gave the lowest mortality and morbidity. With the combined procedure, however, the mortality and morbidity were much higher than after either method alone.

Adult↗
PubMed1975

Sphincter patency and hepatic BSP uptake after biliary sphincterotomy.

An attempt has been made to assess the patency and function of the choledochoduodenal junction after biliary sphincterotomy by estimating the first arrival time of injected bromsulphalein (BSP) in duodenal aspirate and the effect of morphine on this. Studies on 49 patients 1--12 years after this operation showed the arrival time to be normal in 47, but in 2 cases there was delay, which suggests that stenosis may develop in time in abot 4 per cent of cases. This had not been detected clinically, radiologically, or by liver function testing. Although it did not effect the BSP arrival time in T-tube bile, morphine was found to prolong the duodenal arrival time in control patients and also after sphincterotomy of the type used, indicating that the protective mechanism of the sphincter region may not have been destroyed by this operation. Abnormal BSP retention in plasma has been reported up to 5 years afte supraduodenal exploration of the bile ducts in 30 per cent of cases. Similarly, in the present study after biliary sphincterotomy plasma BSP levels were above normal in 14 of 49 patients, suggesting that this abnormality reflects the original pathological condition rather than the type of operation used to deal with it.

Cholecystectomy↗
PubMed1975

13-norleucine motilin versus pentagastrin: contrasting and competitive effects on gastrointestinal myoelectrical activity in the conscious dog.

In conscious fasted dogs, with chronically-implanted electrodes in stomach and small intestine, typical aborally-propagated interdigestive myoelectric complexes were induced by the infusion of 13-nor-leucine motilin (13-Nle-M); whereas when the normal interdigestive activity was abolished by the infusion of pentagastrin, the resulting 'postprandial' pattern of activity was not significantly modified by the administration of 13-Nle-M. Results from this study provide further evidence that Motilin as well as Gastrin may be involved in the control of gastrointestinal motility in dogs.

Animals↗