Balloon tamponade in the management of bleeding oesophageal varices.
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Biomedical subjects
Publications and source records attributed to R Shields.
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Bran was labelled with 99mTc-pertechnetate, ingested as part of a normal meal and used to measure gastric emptying in 15 normal subjects and in 15 patients with ulcerative colitis. There was no significant difference between the gastric emptying curves of the normal subjects and the patients, suggesting that rapid gastric emptying does not contribute to diarrhoea in ulcerative colitis.
Discrepancies exist between reported effects of histamine on the alpha-adrenergic responsiveness of the canine trachealis muscle. Therefore, using an in situ preparation described recently (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 49: 84-94, 1980), we tested the effects of histamine and other agents on alpha-adrenergic responses in the trachealis muscle of 34 anesthetized dogs. Under basal conditions, maximum alpha-adrenergic responses were small [3 +/- 1 (SE) g/cm] compared with those induced by a supramaximal parasympathetic stimulus (45 +/- 3 g/cm). After exposure of the muscle to histamine, responsiveness increased markedly to alpha-adrenergic stimuli, which included tracheal arterial injections of norepinephrine and phenylephrine or electrical stimulation of sympathetic nerves. Augmented alpha-adrenergic responsiveness persisted for 20 min after the end of contractions induced by histamine. Serotonin and long-acting, but not short-acting, cholinergic agonists also potentiated alpha-adrenergic responsiveness. We concluded that exposure of the trachealis muscle in living dogs to a variety of constrictor stimuli potently augmented its alpha-adrenergic responsiveness.
The labelling of o-iodo-hippuric acid (hippuran) with 123I by several methods was investigated with a view to producing a simple one-step kit preparation. The requirements for the final product are high labelling efficiency and high radiochemical purity. A method which incorporates CuSO4 . 5H2O as a catalyst was found which gave promising preliminary results. Such variables as pH, mass of CuSO4 . 5H2O, volume of 0.02 N NaOH containing the 123I, reaction temperature and time were investigated in detail and optimum values obtained. The results have led to the production of a kit which can be stored for up to 3 months in liquid form and up to 9 months if freeze-dried. The kit has been used in several thousand patients and has yielded consistently good clinical results.
In 34 anesthetized dogs, we characterized the pathways by which parasympathetic fibers were carried to the cervical trachealis muscle. Nerves were stimulated electrically, and tracheal tension was monitored in segments of the posterior membrane in vivo as described previously (J.K. Brown et al.; J. Appl. Physiol: Respirat. Environ. Exercise Physiol. 49: 84-94, 1980). Stimulation of superior laryngeal nerves contracted 34 of 34 cranial cervical segments and 2 of 4 caudal cervical segments. Recurrent laryngeal nerves contributed to innervation of 34 of 34 cranial, as well as 4 of 4 caudal, segments. Stimulation of pararecurrent nerves contracted 11 of 34 cranial and 4 of 4 caudal segments. Mechanical effects of esophageal contraction, induced by stimulating pararecurrent nerves, did not alter tension in tracheal segments. Tracheal contractions induced by stimulation of all three pathways simultaneously were significantly less than the sum of contractions produced by stimulating each set individually; this was probably due to anastomoses between terminal neurons, overlap in their anatomic distribution, or intercellular nexuses in trachealis muscle. We conclude that parasympathetic innervation of the canine trachea is by three different neuroanatomic pathways.
In 12 anesthetized dogs, we tested the effects of pharmacologic beta-adrenergic stimulation on the severity of tracheal mast cell reactions in vivo (Am Rev Respir Dis 1979; 119:62). In control dogs, tracheal arterial injections of compound 48/80 produced arteriovenous differences in histamine concentrations across the trachea (35 +/- 15 ng/ml), but not the lung; this finding suggested selective degranulation of tracheal mast cells. Tracheal arteriovenous histamine differences correlated (r = 0.70) with tracheal contractions (12 +/- 4 g/cm) induced by compound 48/80 in these animals. In other dogs, injections of isoproterenol (10 micrograms/kg) before compound 48/80 prevented the development of both tracheal arteriovenous differences and contractions. We concluded that pharmacologic beta-adrenergic stimulation inhibited degranulation of tracheal mast cells. The preparation appears suitable for examining the effects of endogenous stimuli on the severity of mast cell reactions in the central airways of anesthetized dogs.
The absorption of water and electrolytes and intraluminal pressure were measured from Thirty-Vella loops in 4 dogs under basal conditions and during electrical stimulation of the colonic smooth muscle. Pulse wave electrical stimulation via serosal silver/silver chloride electrodes gave rise to significant increases in both intraluminal pressure and percentage motility. Absorption of water, sodium and chloride was significantly increased during stimulation but the transport of ammonia, bicarbonate and potassium was not significantly affected. It is suggested that motility changes result in altered absorption irrespective of transit time.
Capillary blood flow in the canine colon and other organs has been assessed over a wide range of portal pressures using radio-labelled microspheres. The proximal colon received a greater proportionate flow than the distal region. At both normal and raised pressures, the mucosa received 90% of the total colonic capillary flow. A highly significant negative correlation (P less than 0.001) was found between colonic capillary blood flow and portal pressure. A highly significant positive correlation (P less than 0.001) was found between colonic capillary blood flow in the superior mesenteric artery.
The pathogenesis of renal failure in jaundice is controversial. Several factors have been incriminated, including intravascular coagulation. We have investigated this hypothesis by by studying the deposition of radioactive fibrinogen in the kidney of jaundiced rats. Fibrinogen labelled with 125I was injected into rats whose bile duct was subsequently ligated. The radioactivity in the kidney was compared to that in blood and the renal uptake ratio calculated. This ratio (mean +/- s.e.mean) rose from 0.24 (+/- 0.04) to 2.93 (+/- 0.43) after ligation of the common bile duct. In contrast, in control rats who underwent a sham operation, the uptake ratio rose from 0.31 (+/- 0.03) to 0.96 (+/- 0.08). This deposition of 125I fibrinogen in the kidneys of jaundiced rats was significantly greater (P < 0.001) than that in control rats. The deposition was specific to the kidney compared with that in the heart, bowel, muscle and liver. In the control animal the uptake of 125I fibrinogen by the kidney was not different from that by other viscera.
Using a short-lived isotope of zinc (69mZn) with a half-life of 13.9 hr, we have developed a simple test of zinc absorption. After an oral dose of isotope (50 muCi) with 2 mg of elemental zinc a plasma appearance curve was constructed from radioactivity determined in blood samples taken sequentially over 8 hr. Two week later an iv dose of isotope (25 muCi) was administered and a plasma disappearance curve was constructed. Absorption was calculated by computer analysis of appearance and disappearance curves using a deconvolution programme. Mean absorption in five normal subjects was 61% (range 41 to 79%). In three subjects given food with, or 1 hr before the isotope, absorption was delayed and reduced to less than 20% of the oral dose at 8 hr. This test of zinc absorption is simple to perform and, because the isotope has a short half-life, has the advantage of subjecting patients to only limited radiation.
Zinc deficiency is a potential complication of Crohn's disease and we have searched for evidence of this and assessed the possibility that malabsorption of zinc might be a cause. Serum zinc concentrations in 33 patients suffering from Crohn's disease were significantly lower than in 58 normal control subjects (9 . 18 +/- 2 . 3 mumol compared with 13 . 6 +/- 1 . 73 mumol, P < 0 . 0005). Serum zinc correlated well with serum albumin concentrations and the low serum zinc may simply reflect the low serum albumin. Thus its value as an indicator of zinc deficiency is poor. We studied zinc absorption in seven patients with Crohn's disease and compared it with the results obtained previously in five normal subjects using a new technique involving a short-lived isotope of zinc (69mZn). Plasma appearance curves, constructed after an oral dose of isotope, and disappearance curves, after an intravenous dose, were used in a deconvolution computer programme to calculate zinc absorption. Compared with normal subjects, zinc absorption was considerably impaired in patients with Crohn's disease (range 9--45%, compared with 38--75%). This abnormality is a potential cause of zinc deficiency in patients with Crohn's disease.
Splanchnic blood flow was studied over a wide range of portal pressures in five dogs. An inverse linear relationship between flow and pressure was found in the range from 6 to 42 mmHg. The colonic absorption of ammonia, water, sodium, potassium, bicarbonate, and chloride was measured in four dogs over a similar range of portal pressures. Absorption of ammonia, water, sodium, and chloride was significantly reduced by increasing portal pressure, and this reduction was abolished when portal pressure was allowed to return to the basal level. It is suggested that splanchnic decompression by portasystemic shunt gives rise to increased mesenteric flow and increased colonic ammonia absorption, which may contribute to portasystemic encephalopathy.
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In a study of the role of oestrogen-receptor analysis in early breast cancer the oestrogen-receptor content of the tumour was estimated in 286 patients undergoing mastectomy. These patients were followed for up to 39 months, and the recurrence of disease was noted in relation to the presence or absence of oestrogen receptor.Recurrence-rates were significantly higher in patients whose tumours did not contain receptors than in those whose tumours did. This same relationship was seen when women with and without axillary metastases were considered separately. The highest rates of recurrence were in women with axillary lymph-node involvement whose tumours lacked oestrogen receptors. Women without axillary-node involvement whose tumours lacked oestrogen receptors showed the same high rate of recurrence as all women with axillary-node involvement. The oestrogen-receptor content of a primary breast cancer appears to be an independent guide to early recurrence of the disease.
The value of early postoperative feeding with an elemental diet was assessed in 30 patients after major gastrointestinal operations. The patients were allocated at random to conventional treatment (control group) or feeding with the elemental diet (ED group). The clinical and metabolic course of the 15 patients in the ED group was significantly better than that of the controls. Patients in the ED group lost less weight and had a shorter stay in hospital. Negative nitrogen balance was more pronounced in the control group throughout the seven postoperative days. Energy intake was higher in the ED group. Provided elemental feeding is used with caution, it may be given from the first postoperative day. Patients do better metabolically and require shorter stays in hospital.
Measurement of liver blood flow has been carried out by three different methods in 14 dogs to assess the accuracy of xenon-133 clearance following portal vein injection. Electromagnetic flowmetry with flow probes on the hepatic artery and portal vein resulted in a mean value of 121.9 +/- 39.3 ml min-1 100 g-1. An indicator dilution study utilizing chromium-51-labelled red cells gave a mean value of 119.4 +/- 31.4 ml min-1 100 g-1 and the xenon-133 clearance following portal vein injection, 120.3 +/- 33.8 ml min-1 100 g-1. One-way analysis of variance showed no statistically significant variation between these three groups. There was a close correlation between xenon-133 clearance and electromagnetic flowmetry and between xenon-133 clearance and the indicator dilution technique. These data suggest that xenon-133 clearance following portal vein injection gives an accurate assessment of liver blood flow and this technique (as well as direct parenchymal injection) can be adapted for clinical use.