Comparative study of the safety and efficacy of liquid and dry monopolar electrocoagulation in experimental canine bleeding ulcers using computerized energy monitoring

The drawbacks of monopolar electrocoagulation in the control of gastrointestinal bleeding include tissue adherence, unpredictable energy deposition, and a high incidence of tissue damage. Introduction of a conductive interfacial film of liquid between the monopolar electrode and the bleeding point during electrocoagulation may overcome these drawbacks. A prospective, controlled study was undertaken to evaluate the efficacy and safety of a monopolar electrode in liquid and dry modes when used to coagulate experimental canine bleeding ulcers. All experiments were done in open fashion via a gastrotomy with hand-held electrodes. An analog computer, which could be connected between a standard electrosurgical generator and the electrode, was designed and built to monitor and control the energy delivered to the tissue. Both liquid and dry electrodes were highly effective in stopping bleeding. The liquid electrode was found to be superior to the dry electrode in that tissue adherence was eliminated and energy deposition was more predictable, varying less with angle of incidence. The liquid electrode caused less macroscopic serosal damage and less full-thickness histologic damage if the total energy or number of pulses was limited; however, both caused microscopic full-thickness damage in one-half of the experimental ulcers treated, although no perforations occurred.

Combination chemotherapy with 5-fluorouracil (5FU) and 1,3-bis(2-chloro-ethyl)-1-nitrosourea (BCNU) prolongs survival of rats with dimethylhydrazine-induced colon cancer

The effects of combination chemotherapy with 5FU and BCNU on rats with dimethylhydrazine (DMH)-induced colon cancer were investigated in a long term survival study. Eighty Wistar rats received a colon cancer producing regimen on DMH (40 mg/kg body weight/week, subcutaneously for 10 weeks). After presenting with signs of colonic disease, all rats underwent diagnostic laparotomy and colonoscopy when colon tumours were located, measured and the extent of the disease staged. Only animals with tumours (n = 63) were included and allocated to one of three tumour stages. Stage A (n = 17), had colonic tumours without serosal involvement; stage B (n = 28) had serosal involvement without metastases; stage C (n = 18) had serosal involvement with lymphadenopathy and/or metastases. Each group was randomly allocated into two subgroups, one serving as untreated controls while the other received 5FU (300 mg/m2 weekly intragastrically for life) together with BCNU (40 mg/m2 intraperitoneally on days 0, 42 and 84). The effect of chemotherapy on tumour growth was measured sequentially by colonoscopy. Animals were observed until death and necropsied, when colon carcinoma was histologically confirmed and survival analysed. The results indicate that chemotherapy significantly prolongs the survival of rats with the least advanced disease (stage A) but was of no benefit to rats with locally advanced or metastatic disease (stages B and C). Furthermore, chemotherapy was associated with a significant reduction in tumour size. Survival analyses in untreated animals show that the laparotomy staging system adopted provides accurate prognostic information. This study shows that DMH-induced colon tumours are chemosensitive, and suggests that this animal model may be a valuable testing ground for new chemotherapeutic agents.

Effect of sodium taurocholate on gastric secretion in patients with duodenal ulceration

The effect of sodium taurocholate instillation on the stimulated stomachs of patients with duodenal ulceration has been investigated. Instillation into the stomach of sodium taurocholate significantly reduced pentagastrin stimulated volume and outputs of both acid and sodium, with no change in the calculated volume of duodenogastric reflux. These observations are not consistent with the back-diffusion theory, but suggest direct parietal cell inhibition of gastric secretion by sodium taurocholate.

Dietary cholesterol deprivation improves survival and reduces incidence of metastatic colon cancer in dimethylhydrazine-pretreated rats

Cholesterol feeding of rats with colon cancer induced by dimethylhydrazine results in reduced survival and an increased incidence of metastatic colon cancer. As cholesterol may be implicated in the induction or maintenance of the metastatic process, an experiment was designed to determine whether rats with colon cancer would benefit from the removal of cholesterol from the diet. Female Wistar rats were treated with a colon cancer-inducing regimen of dimethylhydrazine (40 mg/kg/week for 10 weeks) while being fed on a standard cholesterol-containing rat pellet diet. After two rats had died spontaneously of histologically proven adenocarcinoma of the colon at 24 weeks, the remaining rats were randomly allocated in groups of 15 to one of three dietary regimens. Group S continued to receive standard pellet diet, group V were fed on Vivonex alone and group VC were fed Vivonex plus cholesterol (10 mg/100 ml Vivonex). Each group was assessed for survival and incidence of histologically proven metastatic disease. There were no differences in either survival or incidence of metastases when groups S and VC were compared. In the cholesterol deprived group V, however, there was a significant increase in survival compared with groups S and VC (p less than 0.02) and this was due to a significant reduction in the incidence of metastases (p less than 0.05). Cholesterol deprivation therefore benefits rats with established colon cancer induced by dimethylhydrazine by improving survival and reducing the incidence of metastases.

The effects of subclinical malnutrition and refeeding on the healing of experimental colonic anastomoses

The effects of dietary protein deprivation on he healing of colonic anastomosis in the rat have been investigated. Nutritional status was assessed both before and after operation using body weight, nitrogen balance studies and serum albumin estimations. Healing of colonic anastomosis was assessed by bursting pressure measurements. Rats fed a protein-depleted diet throughout the study were compared both with rats restored to a full diet after surgery and rats receiving a full diet throughout. Although protein depletion caused a 12.5 per cent weight loss and a negative nitrogen balance, serum albumin remained normal in all rats at the time of operation. After operation, all rats were in negative nitrogen balance, although this was greater in the protein-depleted group. Similarly, in comparison to control animals, the protein-depleted group had significantly lower colonic bursting pressures and significantly lower serum albumin concentrations. Rats returned to a full diet after operation had smaller losses of nitrogen and normal colonic bursting pressures. The results indicate that a commonly encountered degree of malnutrition, insufficient to affect nutritional indices used in clinical assessment, may interfere with colonic healing. Early re-introduction of nutrition in the postoperative period may be able to reverse this effect.

Subtotal colectomy in the dimethylhydrazine-treated rat. A surgical model of colorectal cancer

The effects of subtotal colectomy on the survival of rats with established colon cancer induced by 1,2-dimethylhydrazine (DMH) have been investigated in an attempt to assess whether it might provide a suitable model of surgical treatment of this disease. 40 female Wistar rats received a regimen of DMH injections (40 mg/kg body weight s.c. every 14 days for 10 weeks) known to produce colon cancer. An additional 10 rats received no DMH, serving as controls (group 1). After presenting with signs of colonic disease at 25 weeks, all DMH-treated rats had diagnostic colonoscopy under general anaesthesia, only those with visible neoplasms (n = 34) being included in the study. These were randomised into two groups: group 2 (n = 13) animals were unoperated controls while group 3 (n = 21) animals had a therapeutic subtotal colectomy with histological confirmation of cancer in the resected colon. The animals were observed until death, the postoperative survival and cause of death at necropsy being compared between groups. The results showed that overall survival (p less than 0.013) and survival from death due to colon cancer (p less than 0.001) were significantly increased in the colectomised group 3 animals compared to unoperated controls (group 2). While 91% of the unoperated controls died of colon cancer, only 8% of the colectomised group died of this cause (p less than 0.001), the remainder dying from unrelated causes, predominantly DMH-induced primary extracolonic cancers. Subtotal colectomy in rats with DMH-induced colon cancer reduces mortality from this disease, providing a suitable model of surgical treatment. However, the high incidence of DMH-induced extracolonic cancers may make the model unsuitable for studies of adjuvant therapy.

The effects of cholic acid and bile salt binding agents on 1,2-dimethylhydrazine-induced colon carcinogenesis in the rat

The theory that bile salts may be colon tumour promoters was tested in the dimethylhydrazine (DMH)-induced rat colon cancer model. Fifty Wistar rats were randomly allocated to one of five experimental group (n = 10), all fed the same standard diet. One group served as saline-injected controls, while the other four groups received DMH (20 mg/kg body weight/rat/week s.c.) for 20 weeks. In addition, each of the DMH-injected groups concurrently received 20 weekly i.g. instillations of one of the following: cholic acid (a bile acid); cholestyramine or aluminium hydroxide (both bile acid binding agents), or water. After a years observation period, all the controls were alive and tumour-free, while all the DMH-injected rats had died of histologically proven colon cancer. Irrespective of the type of gastric instillate, there were no significant differences between the groups in terms of time to tumour presentation, survival, in the necropsy incidence of primary or metastatic colon cancer, or in the numbers of colon tumours per group. The data suggest that bile salts and bile salt binding agents are not colon tumour promoters in the rat. The bile salt theory of colon carcinogenesis may need reappraisal.

Experimental colon carcinogenesis is facilitated by endogenous factors in the intestinal contents

The theory that endogenous factors in the intestinal contents may be pathogenic during large bowel carcinogenesis was tested in the dimethylhydrazine (DMH)-induced rat colon cancer model. Thirty female Wistar rats, each serving as their own control, had a surgical transection of the proximal colon with reanastomosis to the rectum, thereby excluding part of the colon from faecal contact. All rats then received a course of DMH (40 mg/kg body wt/wk s.c. for 10 weeks) while fed on Vivonex. This diet was selected because it lacks known exogenous (dietary) cocarcinogens. It also produces mucosal atrophy in functioning (proximal) colon, to parallel the disuse atrophy induced in the defunctioned (distal) colon. Animals remained on the diet throughout the experiment and were killed when moribund or at 40 weeks. At necropsy, the anatomical distribution, number, size and histological type of colon tumours were compared between functioning and defunctioned colonic segments within the same animal. At autopsy, there were significantly fewer colon tumours in the defunctioned segment (P less than 0.005). Furthermore, there were significantly fewer carcinomas (P less than 0.005) and fewer tumours greater than 1 cm diameter (P less than 0.01) in this segment. The data indicate that endogenous factors in the intestinal contents facilitate chemically-induced colon carcinogenesis. Luminal nutrition may be implicated.

Experimental evidence against the bile salt theory of colon carcinogenesis

According to the bile salt theory of colon carcinogenesis, therapeutic agents which increase the delivery of bile salts to the large intestine may promote colon cancer. The possibility that aluminium hydroxide (Aludrox), a bile salt binding agent, might facilitate colon carcinogenesis in vivo was tested experimentally, using the dimethylhydrazine (DMH)-induced rat colon cancer model. 48 Wistar rats were randomly allocated to 1 of 3 groups, all fed the same standard diet. Two groups received a course of ten weekly DMH injections. One was allowed fresh drinking water ad libitum whilst the other received Aludrox in their drinking water. A third group received weekly saline injections plus Aludrox in their drinking water. After 1 year's observation, there were no significant differences between the groups of DMH-injected rats given drinking water with or without Aludrox in respect of survival, necropsy incidence of primary or metastatic colon cancer, or in the total number of colon tumours per group. The results provide reassurance that Aludrox does not promote colon cancer and tend to contradict the bile salt theory of colon carcinogenesis.

Effect of aspirin on gastric acid secretion in the rat

The effects of aspirin on gastric acid and sodium have been studied in a perfused rat stomach preparation. In the pentagastrin-stimulated stomach, as intraluminal aspirin concentration increased, there was a significant fall in acid output together with a significant decrease in the loss of sodium from the gastric lumen. It was concluded that these observations were due to a back-diffusion effect resulting from disruption of the gastric mucosal barrier rather than parietal cell inhibition

The effect of duodeno-gastric reflux on serum gastrin levels in the dog

Serum gastrin has been studied in dogs with and without surgically produced duodenal reflux. Fasting levels and the gastrin response to a standard meal have been assayed using a radioimmunoassay technique. Duodenal reflux caused no significant change in fasting serum gastrin immuno-reactivity but led to a markedly elevated and prolonged gastrin response to a standard meal.

Therapeutic effect of cimetidine in patients undergoing haemodialysis

Blood concentrations of cimetidine were measured and the therapeutic effect of the drug assessed patients undergoing maintenance haemodialysis. Thirteen patients were given a single oral 200-mg dose of cimetidine a mean of 2.7 hours before the start of dialysis. Dialysing for 6--12-6 m2 hours led to a mean fall of 71% in blood cimetidine concentration during haemodialysis. Nine patients with various upper gastrointestinal lesions diagnosed endoscopically were treated for up to six weeks with a reduced cimetidine dose of 200 mg 12-hourly; two patients received two courses of treatment. Repeat endoscopy after treatment disclosed satisfactory healing, and the drug did not accumulate. This lower dose regimen is recommended for patients receiving dialysis who develop upper gastrointestinal lesions for which a histamine H2-receptor antagonist is indicated.

Gastric function and histology in chronic renal failure

Gastric function and histology were investigated in 24 patients with untreated chronic renal failure. At endoscopy nine patients had oesophagitis, 12 patients were considered to have gastritis, and the duodenum appeared inflamed in 20 patients. Endoscopic biopsies were taken at standard sites in the stomach and duodenum; gastritis was found in all patients, and 17 patients had duodenitis. Stimulated acid secretion was impaired in seven out of 20 patients and acid hypersecretion was found in a further two patients. Pepsin output correlated well with acid output in these patients. Fasting serum gastrin levels were elevated in 12 of the 19 patients tested. Patients with atrophic gastritis had low acid outputs and hypergastrinaemia, and when extensive gastritis was present, the patients tended to have more severe renal failure and hyposecretion of acid. Three patients were studied again after regular haemodialysis or renal transplantation and were found to show marked endoscopic and histological improvement.

Effects of bile acids on mucus secretion in the dog colon

The effects of unconjugated bile acids on colonic mucus production have been studied in the dog. Isolated segments of both ascending and descending colon were simultaneously perfused with either chenodeoxycholic, deoxycholic or cholic acid and the mucus production estimated from the total hexose output. Each bile acid produced a significant increase in mucus output in both the right and left colonic segments. There were no differences between the right and left colon in terms of mucus output for any of the bile acids studied. Deoxycholic had a greater effect than chenodeoxycholic which had a greater effect than cholic acid in colonic mucus production. Further, these effects on mucus secretion were completely reversible. In diarrhoea associated with disease or resection of the ileum, the effect of bile acids on mucus secretion may be as important as their effects on the inhibition of water and electrolyte absorption.

Failure of bran to protect against experimental colon cancer in rats

The ability of dietary fibre to prevent colon cancer was tested in rats injected with 1,2-dimethylhydrazine (D.M.H.), a substance which induces cancer of the colon. 60 rats were fed the same formula solid diet but allocated three different amounts of dietary fibre--20 were given 4.8% w/w crude fibre, 20 were given 20% w/w bran, and 20 received no fibre. Half of the animals in each fibre group received a course of subcutaneous D.M.H. and half were given subcutaneous saline. After a year's observation, there was no significant difference in the incidence of, or mortality from, colonic carcinoma between the D.M.H.-treated groups.

Bile composition in bilharzial hepatic fibrosis

At operation for haematemesis in bilharzial hepatic fibrosis, the gallbladder was always found to be diseased but devoid of stones. This led to a study of gallbladder bile composition in a group of bilharzial patients and comparison with a group of cholelithiasis patients. When values for biliary lipid composition were plotted on triangular coordinates, both groups fell well outside the line of maximum cholesterol solubility. The bilharzia group had significantly more cholesterol and less phospholipid than the gallstone group. The absence of stones in patients with bilharzial hepatic fibrosis was possibly due to their early demise and the suggestion is that, in this condition, it is the disease of the gallbladder itself which renders the bile lithogenic.

In vitro effects of gastrin on the movement of electrolytes across the human colon

Using an in vitro system, the effect of gastrin on the colonic handling of water and electrolytes has been investigated. Gastrin converted the normal mucosal absorption of water and sodium into a net secretion. The colonic response to gastrin was done-related with respect to sodium, and the effects were greater when it was added to the serosal side. The potassium handling of the isolated colonic mucosa was not altered by gastrin. At a concentration of 800pg/ml, gastrin signficantly reduced the normal movement of sodium from mucosa to serosa (absorption) but significantly increased serosal to mucosal movement (secretion). This alteration in the bidirectional flux of ions under the influence of gastrin may be clinically important and could account in partt for the diarrhoea associated with the Zollinger-Ellison syndrome.

Bioassay and radioimmunoassay of gastrin and significance of gastrin degradation products

Inactivation of gastrin was studied (a) in vitro by incubation with a high-speed supernatant fraction of rat small bowel mucosa and (b) in vivo by perfusing gastrin through the small bowel vascular bed in anaesthetized dogs. In both types of experiment there was a highly significant loss in the bioactivity of gastrin, but no significant change in its immunoreactivity. This showed that gastrin was inactivated by a subtle chemical change which rendered the molecule biologically inactive, yet left its immunoreactivity unimpaired.

Gallbladder function, cholesterol stones, and bile composition

Gallbladder bile obtained at operation from five patients with no symptoms of biliary disease was undersaturated with cholesterol in every case. However, gallbladder bile from patients with stones composed of 97-100% crystalline cholesterol was on average just saturated with cholesterol when the gallbladder was functioning and undersaturated when it was not. Regardless of gallbladder function, the patients with stones had on average significantly more cholesterol in their bile than in the control group, but the differences between the mean composition of bile from functioning and non-functioning gallbladders were not significant. Common duct bile from patients with non-functioning and functioning gallbladders was on average supersaturated with cholesterol, but there was significantly more bile salt and significantly less cholesterol in the bile from patients with non-functioning gallbladders. Only in the case of patients with functioning gallbladders did the mean composition of the common duct and gallbladder biles differ significantly. The former contained significantly more cholesterol and less bile salt than the latter. It is suggested that patients with non-functioning gallbladders may be 'autocholecystectomised' with the duct bile reverting to a more 'normal' composition.

Gastric acid secretion and diagnosis of Zollinger-Ellison syndrome

One hundred and fifty patients suspected of having Zollinger-Ellison syndrome were investigated. High plasma gastrin levels were found in 23 and in 16 a diagnosis of Zollinger-Ellison syndrome was confirmed. Measurement of the basal and maximal acid outputs showed that these simpler investigations have considerable value as screening tests for the selection of those patients in whom gastrin studies are indicated.

Effect of proximal gastric vagotomy on gastric acid secretion and plasma gastrin

Sixteen patients underwent proximal gastric vagotomy (highly selective vagotomy) for chronic duodenal ulceration. All were subjected to preoperative and postoperative acid secretion studies. A reduction in the secretory response to pentagastrin and abolition of the response to meat extract occurred postoperatively. Plasma gastrin levels in response to meat extract were studied by radioimmunoassay. Basal plasma gastrin levels were unaffected by vagotomy and it was found that the plasma gastrin response to meat extract was not impaired after operation if the postoperative insulin test was positive. Only if the insulin test was negative was the amount of gastrin released by meat extract reduced.

Zollinger-Ellison syndrome type 1: clinical and pathological correlations in a case

Some patients with the Zollinger-Ellison syndrome appear to have hypergastrinaemia and hyperplasia of the antral G cells but no tumour. This subgroup has been classified as Zollinger-Ellison syndrome type 1. We have treated such a patient by vagotomy and antrectomy, the fasting plasma gastrin and acid secretion subsequently returning to normal.A 17-year-old male had a four-year history of duodenal ulcer. Gastric secretion tests showed acid hypersecretion. Fasting plasma gastrin was 8350 pg/ml (normal 50-170 pg/ml). At laparotomy duodenal ulceration was confirmed but no pancreatic or other tumours were found. Truncal vagotomy and antrectomy was performed with distal pancreatectomy. Immunofluorescent staining showed hyperplasia of G cells in the resected antrum but a normal pancreas and duodenum. Six months after operation he was symptom free and acid secretion was reduced by 92%. The fasting plasma gastrin at two months was <50 pg/ml. These findings suggest that type 1 Zollinger-Ellison syndrome may be a clinical entity.

Plasma gastrin and acid secretion in man following stimulation by food, meat extract, and insulin

A radioimmunoassay for gastrin was set up and its sensitivity and specificity were studied. The assay was then used to investigate the plasma gastrin responses in man to a normal meal and to stimulation by insulin hypoglycaemia or by instilling meat extract into the stomach. The results showed that insulin and meat extract produced very similar plasma gastrin responses which were certainly not less than those produced by feeding. However, the acid secretory response to insulin was greater than that to meat extract. This indicated that the tests acted in different ways and both may be useful in the assessment of gastric secretion.

Plasma calcium fractions and the protein-binding of calcium in normal subjects and in patients with hypercalcaemia and hypocalcaemia

A study is reported of the estimation of plasma calcium fractions and the calcium-binding affinity of plasma proteins in a total sample of 59 people, which included 29 normal subjects and 30 patients with either hypercalcaemia or hypocalcaemia. It was demonstrated that when the sample was considered as a whole there was a significant correlation between the total plasma calcium concentration and the ultrafiltrable, ionized, and protein-bound calcium fractions and between the ultrafiltrable and ionized fractions. We have also demonstrated that in patients with either hypercalcaemia or hypocalcaemia, including acidotic uraemics, the calcium-binding affinity of the plasma proteins did not differ significantly from that in normal subjects. A significant correlation was also found between the total plasma calcium concentration and the ultrafiltrable, ionized and protein-bound calcium fractions when the normal subjects and the groups of patients with hypercalcaemia and hypocalcaemia due to chronic renal failure were considered as separate groups. The group of patients with hypercalcaemia included patients both with hyperparathyroidism and with hypercalcaemia due to other causes.

Ultramicrofluorimetric determination of calcium in plasma

A precise and reproducible method is described for the ultramicro fluorimetric determination of calcium in plasma, based upon the formation of a fluorescent complex between calcium and calcein at a strongly alkaline pH. In a group of normal subjects, the mean concentration of plasma calcium was 9.66 mg/100 ml with a normal range of 8.9 to 10.4 mg/100 ml.