Protection of thermochemotherapeutic-induced lethal acute hepatic necrosis in the rat by 16,16-dimethyl prostaglandin E2

These studies further evaluate the hepatocytoprotective properties of 16,16-dimethyl prostaglandin E2 (dmPGE2) by assessing its effect on survival, liver function, and hepatic regeneration in a model of in vivo isolated perfusion of the rat liver with high concentrations of cytotoxic drugs and regional hyperthermia. Isolated perfusion with 1.0 g/kg of 5-FU or hyperthermia of 41 degrees C X 10 min resulted in 90-100% mortality in control rats, with extensive, patchy necrosis and infarction on histologic examination, and markedly elevated levels of SGOT and SGPT at 24 hr after perfusion. Pretreatment with dmPGE2 (10 micrograms/kg sc) at 30 min before, and at 6 and 24 hr after hepatic perfusion significantly improved survival to 80% (P less than 0.01) following 5-FU perfusion and to 40% (P less than 0.05) following hyperthermic perfusion. Animals were followed for at least 21 days after perfusion and demonstrated normal liver histology, dmPGE2-treated rats demonstrated significantly lower SGOT and SGPT levels at 24 hr after perfusion. dmPGE2 (2 micrograms/kg sc) given as above improved the length of time of survival but eventual mortality was not significantly improved. Oral administration (50 micrograms/kg po at 30 min before, 6 and 24 hr after perfusion) and posttreatment (10 micrograms/kg sc at 1, 6, and 24 hr after perfusion) had no significant effect on survival. Hepatic regenerative capacity following partial hepatectomy was severely suppressed following isolated hyperthermochemotherapeutic hepatic perfusion. Pretreatment with dmPGE2 (10 micrograms/kg sc) restored the DNA synthetic response in perfused rats to that seen in normal control rats after partial hepatectomy (P less than 0.05 and P less than 0.01). The results from these studies further confirm the role of dmPGE2 as a hepatocytoprotective agent and suggest potential clinical application in situations where there has been deliberate, therapeutic insult to the liver.

Portal hypertension and gastric mucosal injury in rats. Effects of alcohol

The present study was performed primarily in order to determine whether gastric mucosa of rats with portal hypertension has different functional and histologic features when compared with controls, and second to quantitate and compare morphologic and functional changes after exposure to topical ethanol. Portal hypertension was produced by staged portal venous occlusion, and in these animals portal pressure was 32 +/- 2 cm saline compared with 18 +/- 2 cm in sham-operated controls (p less than 0.005). Before ethanol, portal hypertensive rats compared with controls had significantly higher luminal pH (2.9 +/- 0.3 vs. 1.9 +/- 0.1), increased H+ back-diffusion (loss of 138 +/- 10 vs. 57 +/- 16 microEq H+/h), lower potential difference (8 +/- 1 mV lower than controls), and extensive submucosal edema (submucosal thickness 325 +/- 25 vs. 138 +/- 18 micrometers). After 3 h of exposure to 2 ml intragastric absolute ethanol, the area of macroscopic hemorrhagic mucosal injury was significantly greater in portal hypertensive rats than in controls (34.0 +/- 8.7% vs. 7.6 +/- 2.1%), confirmed histologically by the greater number of deep hemorrhagic necrotic lesions and extent of mucosal length involved. Furthermore, after ethanol, portal hypertensive rats compared with controls had significantly increased gastric volume (14.4 +/- 1.5 vs. 8.3 +/- 0.6 ml), Na+ (86.6 +/- 8.0 vs. 64.6 +/- 8.0 mEq/L), pH (7.1 +/- 0.3 vs. 4.3 +/- 0.4), H+ back-diffusion (loss of 309 +/- 41 vs. 207 +/- 33 microEq H+/h), and protein and blood loss (100% increases over controls). These results indicate that gastric mucosa of portal hypertensive rats has distinctive functional and histologic abnormalities that can explain its increased susceptibility to erosive injury after ethanol. This study quantitatively confirms in an animal model the clinical observations that portal hypertension may predispose to severe gastric mucosal injury.

Immunologic status in infants and children following surgery

The investigation of cellular and humoral immunologic parameters (T and B lymphocytes and immunoglobulins) with respect to postoperative infection in children revealed changes in the T lymphocytes in particular. Preoperative complications (ileus, shock, infection), anesthesia and surgery lead to transient immunosuppression. The duration of this T cell suppression is age-dependent; suppression is longest in newborns (up to three weeks on the average) and shortest in older children (one week on the average). IgA and IgG concentrations show only slight abnormal changes; IgM concentrations, however, increase significantly during the postoperative period in all age groups. Prophylactic and therapeutic measures for the prevention of postoperative infections can be considered on the basis of immunologic changes related to surgery.

Ethanol, essential fatty acids and prostaglandins

In the body the essential fatty acid (EFA) linoleic acid (18:2, omega-6) is desaturated and chain elongated to form homo-gamma-linoleic acid (20:3, omega-6) and arachidonic acid (20:4, omega-6). Apart from their structural function in cell membranes, the EFAs serve as precursors to the prostaglandins and related substances. The prostaglandins can, in general terms, be described as a defensive regulatory system of importance for cardiovascular, gastrointestinal and urogenital function. Acute intake of ethanol gives facial flushing, inhibition of platelet aggregation and elevation of tissue c-AMP. These effects are consistent with release of vasodilatory and antiaggregating PGs. In epidemiological studies, moderate ethanol intake offers some protection against coronary heart disease. Chronic intake high doses of ethanol is associated with damage to, e.g., liver, heart, brain, immunoregulation and various hormonal systems. Decreased tissue levels of 18:2, 20:4 and PGs have been observed both in animals and man. The conversion of 18:2 to 20:4 is inhibited by chronic ethanol exposure. It is suggested that ethanol depletes the PG precursor pool by a dual mechanism of releasing precursor acids and by inhibiting their synthesis. This would lead to a functional EFA-deficiency, manifested by a hypoactive PG system.

Gastrointestinal propulsion measurement with radiopaque capsules during 16,16-dimethyl PGE2 infusion

A method to quantitate gastric emptying (GE) and small intestinal transit (SIT) by obtaining serial abdominal x-rays after administration of radiopaque capsules was developed. The technique was verified by studying gastric emptying and small intestinal transit in healthy volunteers treated with subcutaneous injections of 0.4 or 0.8 mgs of atropine, 2.5 mg bethanechol, or saline placebo. Atropine decreased gastric emptying and small intestinal transit, and bethanechol only increased gastric emptying. The suitability of this technique for measuring gastrointestinal propulsion in post-operative patients was demonstrated in females undergoing hysterectomy. The small intestine recovered propulsive ability at least six hours sooner than the stomach. This technique was also used while performing a single dose, intravenous tolerance study of 16,16-dimethyl prostaglandin E2 (DmPGE2) in normal volunteers. DmPGE2 was administered over five minutes at a dose of 7 to 140 ng/kg. DmPGE2 was well tolerated producing only minor side effects that were not dose related. In doses up to 70 ng/kg, DmPGE2 increased gastric emptying and inhibited small intestinal transit. The delayed small intestinal transit may make DmPGE2 an inappropriate choice for treatment of post-operative or paralytic ileus.

The action of porcine glucagon on the motility of the canine duodenum and jejunum

1 Intravenous bolus doses of porcine glucagon of 0.001-0.05 mg kg-1 caused intense stimulation of the duodenum and jejunum of the dog. 2 Intravenous infusion of porcine glucagon at 0.025-0.05 mg kg-1 h-1 caused similar stimulation. In both cases the stimulation was phasic in nature. 3 Stimulation of the duodenum and jejunum following glucagon was accompanied by a decrease in frequency of the intestinal basic electrical rhythm (BER). No change was seen in the intervals between successive periods of phase III motor activity.

Effect of pentagastrin on parietal cell ultrastructure in glucagon-pretreated subjects

The effect on parietal cells of glucagon given prior to pentagastrin is unknown. Fifteen healthy volunteers were studied during constant intravenous infusion of pentagastrin (2 micrograms/kg body weight/hr) and during pentagastrin infusion initiated 20 min after intravenous injection of 2 mg glucagon. Three types of studies were performed: Gastric mucosal biopsies were obtained with a Quinton instrument. Electron micrographs of 320 parietal cells were analyzed by the Loud quantitative method, and intragastric pH (pH probe), or gastric potential difference (PD) were recorded continuously. Pentagastrin infusion produced a significant increase in canalicular and simultaneous reduction of tubulovesicular membrane area of parietal cells. Glucagon pretreatment did not inhibit canalicular and tubulovesicular membrane reaction to pentagastrin; unexpectedly this reaction was significantly greater when compared to that after pentagastrin alone. Initiation of pentagastrin infusion in subjects pretreated with glucagon produced a greater absolute value drop in gastric PD (23 +/- 2 mV) and an earlier drop in intragastric pH (3 min) than in subjects receiving pentagastrin infusion alone (13 +/- 1 mV and 10 min, respectively). In conclusion, at the doses studied, glucagon pretreatment increases parietal cell canalicular reaction to pentagastrin.

Patterns of hepatocyte injury in man

Three patterns of hepatocyte injury in man, direct, immunological, and cholestatic, are described. The characteristics of the direct pattern are predominantly mitochondrial damage, central (zone 3) necrosis, and, usually, fatty change. It can be subdivided into the alcohol type (also seen with obesity, in diabetes, as a reaction to perhexiline, in Wilson's disease, and in Indian childhood cirrhosis) and the Reye's syndrome type (also seen with tetracycline toxicity, fatty liver of pregnancy, and cytotoxic drugs). Reactive drug metabolites, metal poisoning, and anoxia are also associated with the direct pattern of hepatocyte injury. The immunological pattern is characterised by damage to cell membranes with piecemeal necrosis of periportal (zone 1) hepatocytes and mononuclear-cell infiltration. Examples include chronic active hepatitis, primary biliary cirrhosis, and drug reactions such as those to halothane. In the cholestatic pattern there is disturbance of the bile-secretory mechanism with retention of bile within the hepatocytes. Cholestatic liver injury may be intrahepatic, as in sex-hormone cholestasis, or extrahepatic, as in choledocholithiasis or carcinoma of the bile ducts. Identification of the type of hepatocyte injury is valuable in diagnosis, in assessing prognosis, and in selecting treatment.

Relationship between lesion formation and permeability of rat gastric mucosa to H+ and other cations

The relationship between lesion formation and ionic permeability has been investigated in rat gastric mucosa in vivo. Changes in these parameters were measured in the mucosa treated topically with prostaglandins E2 and A2 and/or aspirin. Particular attention was paid to the net flux of H+ ions across the gastric mucosa. The effect of aspirin concentrations of 5 mM, 20 mM and '40 mM' (the latter, a suspension in a saturated solution) was investigated. Aspirin concentrations of 20 mM and '40 mM' produced a marked increase in lesion formation and increased the net mucosal to serosal flux of H+ ions. Aspirin 5 mM produced a significant increase in lesion formation but did not cause a significant change in net H+ ion flux. This result suggests that aspirin can have a direct irritant effect on the gastric mucosa and that the back diffusion of H+ ions is not a pre-requisite for the development of overt mucosal ulceration. The effect of topically applied prostaglandin E2 (PGE2) on aspirin-induced gastric mucosal damage was investigated. Concentrations of PGE2 of 10(-5) M and 10(-4) M ameliorated aspirin-induced damage, but these changes were not necessarily accompanied by a significant reduction in net H+ ion flux. Again, this result is not consistent with a direct relationship between lesion formation and mucosal permeability to H+ ions. Since PGA2 did not ameliorate aspirin-induced mucosal damage, the protective effect of PGE2 could not be attributed to its conversion to PGA2 in the acidic environment of the gastric lumen. 5 Changes in gastric mucosal potential difference (p.d.) and net fluxes of Na+ and K+ ions may occur without a concomitant change in the permeability of the gastric mucosa to acid back-diffusion. Thus, the assumption cannot be made that a change in the permeability of the gastric mucosa to one particular ion reflects a general increase in ionic permeability.

Effect of low dose of cimetidine on gastric potentials difference and acetylsalicylic acid-induced change

Cimetidine in a low dose of 10 mg given intravenously increases significantly the gastric potential difference (GPD) without any inhibitory effect on gastric acid secretion. The increase of GPD after 200 mg cimetidine is higher than after 10 mg. While the high dose of cimetidine prevents the acetylsalicylic acid (ASA)-induced GPD drop, cimetidine in a dose of 10 mg is not able to protect this change. Nevertheless the low dose of cimetidine may have a clinical significance and should be evaluated by clinical studies.

Effect of glucagon on human gastric mucosa: histochemical studies

We studied the effects of glucagon (2 mg intravenously) on the histochemical localization and staining intensity of 10 enzymes in human gastric mucosa. Glucagon caused a significant increase in the histochemical activity of glucose-6-phosphate dehydrogenase in the undifferentiated neck cells and mucous cells of the foveolae and of ATPase activity in and around the mucosal capillary walls. Glucagon also stimulated mucus secretion from the surface epithelial cells. These changes were observed 15 and 30 min after glucagon in the oxyntic, but no pyloric mucosa. they indicate that glucagon, in addition to its effect on parietal cells, also affects other structures in human gastric mucosa.

Fine-morphology of chief cells in human gastric mucosa after secretin

Quantitative ultrastructural studies of human gastric mucosal chief cells during secretory stimulation have not been reported previously. In five healthy subjects we studied the effect of intravenous administration of 2 CU/kg of GIH secretin on gastric chief-cell ultrastructure. Gastric biopsies for quantitative ultrastructural analysis were obtained before and 15 and 30 min after secretin administration. Electron micrographs of 150 chief cells were analyzed by the Loud quantitative method. After secretin administration the percentage area occupied by zymogen granules decreased significantly at 15 and 30 min. At corresponding times membrane profile concentration (rough endoplasmic reticulum) increased significantly over basal values. This study provides morphological evidence of increased activity of chief cells after secretin administration.

Effect of human gastrin infusion on gastric potential difference in man

Human gastrin I heptadecapeptide, infused intravenously to healthy volunteers in a dose of 0.5 micrograms/kg/hr, caused a prompt, significant reduction in gastric potential difference (decrease of mucosal negativity), with the peak change at 6 min. This decline in potential difference occurred at a time when the serum gastrin level was between 24 and 83 pg/ml; at the same time, scanning electron microscopic examination of fractographs of parietal cells demonstrated marked increase in canalicular membrane area. This study shows that the decrease in potential difference after gastrin occurs with serum gastrin levels which are in the physiologic range.

Effect of various stimulants and inhibitors of gastric acid secretion on mucosal potential difference in man

Pentagastrin and histamine in doses effective in stimulating gastric acid secretion (5 microgram/kg/h intravenously and 25 microgram/kg intramuscularly, respectively) produce a significant decrease in the gastric mucosal potential difference (PD) in man. In contrast, atropine and cimetidine (2 mg/30 min intravenously and 4.5 mg/kg/h intravenously respectively) cause a significant increase in gastric PD. The subsequent or simultaneous administration of cimetidine reverses the effect of the stimulating agents on gastric PD and pH. Similarly, the subsequent administration of pentagastrin reverses the effect of atropine. The intragastric instillation of 100 c HCl 0.1 N increases significantly the gastric PD valuesp in this case the patterns of PD and pH changes are dissimilar. This study indicates that substances that modify gastric acid secretion also induce changes in gastric PD; this last effect does not seem to depend on variations of the intragastric pH. Therefore, in the clinical evaluation of the gastric PD in man, its multifactorial origin must alway be considered.

Quantitative ultrastructural analysis of the human parietal cell during acid inhibition and increase of gastric potential difference by glucagon

Glucagon inhibits gastric acid secretion and increases the negativity of gastric mucosal potential difference (PD) in man. To test the hypothesis that the increased negativity of PD after glucagon in man could be due to decreased parietal cell canalicular membrane area, a quantitative ultrastructural analysis was carried out. Four healthy volunteers with normal gastric mucosa were submitted to biopsy before and 20 minutes after intravenous injection of 2 mg glucagon (G). This time corresponded with the maximal change in PD and a decrease in gastric acid secretion. Canalicular and tubulovesicular membrane area of 80 parietal cells (40 cells before glucagon and 40 cells after glucagon) were quantified by the Loud morphometric method. After glucagon, the oxyntic cell canalicular membrane area was reduced by one-fourth (P less than 0.05), while tubulovesicular membrane area showed an increase (P less than 0.05) at the same time. The decrease in the area of parietal cell canalicular membrane caused by glucagon may in part be responsible for increased negativity of the gastric PD caused by this hormone.

Long term effect of systemic tetracycline administration on the severity of induced periodontitis in the rat

The present investigation was undertaken to determine the influence of systemically administered tetracycline on periodontitis in the rat. Thirty Sprague-Dawley rats were arranged into two groups, one group received 21 mg of tetracycline hydrochloride each day for 10 weeks in the drinking water. Periodontitis was induced in the maxillary left segment with a 0.008 inch stainless steel ligature wire and by modifying the normal diet with sucrose. The direct microscopic and histometric measurements obtained were analyzed for statistical significance, which revealed the following: 1. Tetracycline-treated animals demonstrated significantly less resorption of the buccal alveolar bone. There were no statistical differences however, in the amount of alveolar bone resorption palatally or interdentally. 2. Tetracycline-treated animals demonstrated significantly less apical migration of the junctional epithelium on the distal root of the maxillary first molar tooth. 3. Tetracycline-treated animals demonstrated significantly fewer inflammatory cells. In conclusion, long term systemic administration of tetracycline in the rat may be of value in reducing the amount of tissue destruction in experimentally induced periodontitis.

Association of sepsis with an immunosuppressive polypeptide in the serum of burn patients

One hundred ninety serum samples from 51 burned patients were tested for immunosuppressive activity which might explain decreased host immune competence following thermal injury. The serum from a variable but significant percentage of these patients suppressed the response of normal human peripheral blood lymphocytes to phytohemagglutinin. The occurrence of immunosuppressive activity paralleled the severity of the injury. Ten of ten severely burned patients (severity index greater than 40), but only 20 of 30 patients with index 10--39.9, and three of 11 patients with Index 0--9.9 developed suppressive serum. Differences between these groups were significant (p less than .05). In all 19 patients who became septic, immunosuppressive serum activity immediately preceded or coincided with the septic episode. In contrast to the effect on lymphocytes, burn sera stimulated fibroblast proliferation. Immunosuppressive activity did not correlate with serum cortisol levels, blood transfusion, protein-calorie malnutrition, or anesthesia. Suppressive sera were not cytotoxic. A majority of the active serum factor(s) was contained in a low molecular weight (less than 10,000 daltons) polypeptide subfraction.

Controlled trial of prophylactic antibiotics in minor wounds requiring suture

Minor wounds presenting in the accident department requiring suture were randomly allocated to one of three treatment groups: an intramuscular injection of 1-25 megaunits of penicillin as a long-acting depot preparation, local wound irrigation with 100mg of tetracycline in solution, or no antibiotics. All wounds had a standard surgical toilet and were closed under aseptic conditions. Wound infections were noted five to seven days after suture, and in the two groups receiving antibiotics 23% of the wounds were infected whilst in the control group the frequency was 7%. The wisdom of using routine antibiotic prophylaxis in minor wounds is questioned.