Ken Hirabayashi

Role of Blood Flow in Gastric and Duodenal Mucosal Injury in the Rat

The hemorrhagic hypotension model in anesthetized rats was used to study the relationship between gastric and duodenal mucosal blood flow and susceptibility to acid-induced injury. Mucosal blood flows measured by the hydrogen gas clearance technique in the corpus, antrum, and duodenum all showed a significant linear correlation with mean blood pressure, decreasing progressively as blood pressure fell. Significant gastric mucosal lesions occurred only after mean blood pressure and hence, mucosal blood flow was reduced to below 40% of baseline values. In contrast, duodenal mucosal lesion formation was related in a linear manner to decrease in mean blood pressure or blood flow. We conclude that mild reductions in blood flow are more important in the duodenum than in the stomach in increasing susceptibility of the mucosa to acid-induced injury.

Prospective randomized comparative study of bipolar electrocoagulation versus heater probe for treatment of chronically bleeding internal hemorrhoids

BACKGROUND Our purpose was to compare the efficacy, complications, failure rates, and crossovers of heater and bipolar probe treatments of chronically bleeding internal hemorrhoids. METHODS Eighty-one patients (31 female, 50 male) with mean age of 53 years had large (grade 2 to 3) internal hemorrhoids with bleeding for a mean of 12 years, had failed medical management, and were randomized in a prospective study of anoscopic treatments to heater versus bipolar probes. Failure was defined as a major complication or failure to reduce the size of all internal hemorrhoids with three or more treatments. RESULTS With similar background variables and no difference in treatment times, rectal bleeding and other symptoms were controlled in a shorter time with the heater probe than with the bipolar probe (77 versus 121 days). Five complications (fissures, bleeding, or rectal spasm) occurred with the bipolar probe, and two occurred with the heater probe. The heater probe caused more pain during treatments but had significantly fewer failures and crossovers. CONCLUSIONS For patients who had failed medical management of chronically bleeding internal hemorrhoids, the techniques and complications of heater and bipolar probes were similar, but pain was more common, failures and crossovers were less frequent, and the time to symptom relief was shorter with the heater probe than with the bipolar probe.

Prospective randomized comparative study of bipolar versus direct current electrocoagulation for treatment of bleeding internal hemorrhoids

Internal hemorrhoids are the most common cause of lower gastrointestinal bleeding. Although new anoscopic therapies are available, few comparative randomized studies have evaluated them in regard to long-term efficacy, recurrence rates, and safety. Our purpose was to compare the treatment of internal hemorrhoids with direct current (Ultroid, Cabot Medical, Langhorn, Pa.) and bipolar (BICAP, Circon ACMI, Stamford, Conn.) hemorrhoid probes. One hundred patients with symptomatic internal hemorrhoids were randomized: 50 to direct current electrocoagulation and 50 to bipolar electrocoagulation. Follow-up and treatment were at 3- to 4-weekly intervals; two to three hemorrhoid segments were treated at each session until relief of symptoms (bleeding, prolapse, and discharge) and a reduction in hemorrhoid size to grade 1 or 0 were noted. The hemorrhoids of 98% of all patients studied were grade 2 or 3; 2% of patients had grade 1 hemorrhoids and none had grade 4 hemorrhoids. At 1 year after treatment, most patients had no (69%) or only mild (23%) recurrence, and a few had severe, symptomatic (8%) hemorrhoid recurrence. A greater recurrence rate was noted after direct current treatment (34%) than bipolar treatment (29%). In contrast, rebleeding at 1 year occurred less frequently after direct current treatment (5%) than after bipolar treatment (20%). Our conclusions were as follows: (1) Both direct current and bipolar probes were effective for control of chronic bleeding from grade 1 to 3 internal hemorrhoids. (2) Bipolar probe was significantly faster than direct current probe. (3) Direct current treatment produced fewer complications than bipolar treatment (12% versus 14%). (4) Recurrence rates were low after 1 year with either device (8%).(ABSTRACT TRUNCATED AT 250 WORDS)

Randomized controlled study of injury in the canine right colon from simultaneous biopsy and coagulation with different hot biopsy forceps

BACKGROUND Monopolar hot biopsy forceps (HBF), bipolar HBF, and cold biopsy forceps (CBF) followed by bipolar electrocoagulation are used clinically to simultaneously perform a biopsy and coagulate diminutive colon polyps and angiomata. Our purpose was to conduct a randomized, controlled study to evaluate the safety of these different techniques in the canine right colon. METHODS After right colotomy in 8 mongrel dogs, colonic mucosa was grasped en face, tented, and biopsy performed in randomized order. The dogs were sacrificed after nine days and the biopsy sites were identified and histologically examined. RESULTS Monopolar HBF caused an overall mean rate of acute serosal whitening of 29% compared with 0% for bipolar HBF and CBF and 6% for CBF/bipolar probe. Histologically confirmed transmural injury 9 days after biopsy occurred in 44% of monopolar HBF compared with 5% of bipolar HBF, 0% of CBF, and 50% of CBF/bipolar probe. CONCLUSIONS Monopolar HBF had significantly higher rates of acute serosal whitening and histologic transmural damage than bipolar HBF or cold biopsy alone. On the basis of these results, monopolar HBF should be avoided for coagulation of small or flat right colon lesions such as diminutive polyps or angiomata.

Octreotide decreases canine gastric mucosal blood flow: A controlled assessment by endoscopic reflectance spectrophotometry

The aim of this study was to evaluate the effects of octreotide, a long-acting somatostatin analogue, on canine gastric mucosal blood flow and hemodynamics. We hypothesized that octreotide might decrease gastric mucosal blood flow without causing adverse hemodynamic effects. Two groups of dogs were anesthetized (six normal dogs and six dogs with prehepatic portal hypertension), and each dog was administered intravenous octreotide, normal saline solution, and vasopressin for 30 minutes on separate days in a blinded, randomized fashion. Vasopressin was included as treatment for a positive control. Gastric mucosal blood flow was assessed at the fundus, corpus, and antrum by endoscopic reflectance spectrophotometry. A femoral arterial catheter monitored systemic blood pressure and heart rate. Treatment responses for all observations were calculated for each dog as a percentage of baseline values. For mucosal blood flow, treatment responses did not differ significantly over time or between animal group or gastric location. Octreotide significantly decreased indices of hemoglobin concentration (-19%, p = 0.01) and oxygen saturation (-17%, p = 0.0002) compared to saline (-9% and -7%, respectively). The mean arterial pressure was increased after octreotide compared to saline (+23% versus +7%, p = 0.01), but octrotide had no effect on heart rate (+2% versus +1%). Vasopressin also decreased the indices of hemoglobin concentration (-34%) and oxygen saturation (-82%) significantly more than saline (p = 0.001). Vasopressin increased mean arterial pressure (+55%), but also caused reflex bradycardia (-22%) significantly more than saline (p = 0.001). We conclude that octreotide decreases canine gastric mucosal blood flow and appears to cause minimal hemodynamic changes.

The effect of histamine on microvascular permeability in the muscularis externa of rat small intestine

Using in vivo microscopy and a fluorescent tracer, the effect of histamine on microvascular permeability was determined in the muscularis externa of the small intestine of anesthetized rats. The small intestine was exteriorized and epilluminated using a microscope equipped with a vertical illuminator and appropriate filters. Fluorescein isothiocyanate conjugated to serum albumin was injected intraarterially. Studies were monitored and videotaped using a closed-circuit television system. Topical application of histamine resulted in focal leak of the conjugate from microvessels in the muscularis externa. The extent of leakage was quantitated by determining the area of leaks through use of a grid over the face of the videomonitor. Dose response studies were performed with histamine alone and plus H1- and H2-receptor antagonists, and with H1 and H2 agonists. The findings demonstrated that histamine increased microvascular permeability to macromolecules in rat small intestine muscle in a dose-dependent manner. This effect was mediated by H1 histamine receptors.

Prostaglandin cytoprotection. Prostaglandin does not protect against aspirin- or alcohol-induced red blood cell hemolysis.

The hypothesis that prostaglandin cytoprotection involves cell membrane stabilization was testedin vitro using rat erythrocytes. Low concentrations of sodium acetylsalicylate, 0.02, 0.2, 2.0, and 20 mM, inhibited hypotonic hemolysis of red blood cell suspensions. While 35, 140, and 280 mM sodium acetylsalicylate had no hemolytic effect, 560 mM caused marked hemolysis. The prostaglandin E2 analog, 16,16-dimethyl prostaglandin E2, 0.4×10−3, 10−4, and 10−5 M concentrations, did not alter this hemolysis. Fourteen percent ethanol caused red cell hemolysis, and this was unaffected by the prostaglandin. The findings do not support the hypothesis.

3544 Randomized double blind study of efficacy and safety of ethanolamine-alcohol mixtures or morrhuate for hemostasis of bleeding canine gastric varices.

Gastric variceal (GV) bleeding is a difficult problem, but endoscopic sclerotherapy is not commonly used for hemostasis. Our purpose was to compare the safety and efficacy of ethanolamine (ET) and alcohol (AL) mixtures with morrhuate in a double blind study for hemostasis of bleeding GV. Methods: 10 prehepatic portal hypertension adult mongrel dogs with 4-5 moderate sized GV were heparinized. After bleeding was induced with a 16G needle, each bleeding GV was randomized to Rx with one of 5 solutions (in coded fashion, see table) in 1-1.5 cc injections until complete hemostasis or a maximum of 10 ccs was injected. The endoscopist was blinded to the solutions and the code was broken after the statistical analysis. A suction test was performed at 5 minutes after hemostasis to judge early rebleeding and stability. Endoscopies were performed at 7 days to assess GV grade changes (Δ) in size, secondary ulcers, and stigmata. See the table. Conclusions: 1) This animal model of GVs was useful for testing the safety and efficacy of different sclerosants prior to human use. 2) Morrhuate had a low hemostasis rate, high rates of large ulcerations, and frequent stigmata. It cannot be recommended for GV hemostasis in patients. 3) 3.3% ET/33% AL had the highest primary hemostasis rate & shortest treatment time. It was safer than morrhuate and is recommended for GV hemostasis in patients. Partial research funding was from Cypros Pharmaceutical Corp. and by CURE grant NIH 41301.