Biomedical subjects

M P Hocking

Publications and source records attributed to M P Hocking.

At least 19 recordsLinked to original sources

PubMed1995

Vasoactive intestinal peptide and substance P receptor antagonists improve postoperative ileus.

Octreotide, a somatostatin analogue that inhibits the release of most gut peptides, hastens the resolution of experimental postoperative ileus, suggesting that gut peptides mediate this process. We studied the role of two gut peptides involved in the control of normal gut motility, vasoactive intestinal peptide (VIP), and substance P (SP), in the initiation and maintenance of postoperative small bowel ileus in rats by preoperative administration of VIP and SP receptor antagonists, (VIP-ra and SP-ra). Thirty male Sprague-Dawley rats (300-350 g) underwent laparotomy. One half underwent placement of a duodenal catheter for transit studies while the other half had serosal electrodes placed on the proximal jejunum for myoelectric recordings. Six days later, animals were separated into three treatment groups of five each. Control animals were pretreated with ip saline, while the others received either VIP-ra or SP-ra prior to standardized laparotomy. Following abdominal closure, [Na51]CrO4 was injected into the duodenum and the animals were sacrificed 25 min later. The small bowel was then excised and divided into 10 equal segments. Small bowel transit was calculated as the geometric center of [Na51]CrO4 distribution. The interval until the return of migrating myoelectric complexes (MMCs) was determined in animals with intestinal electrodes. VIP-ra-treated rats demonstrated a 67% improvement in the geometric center of radiolabel relative to controls and SP-ra-treated rats had a 23% improvement (3.67 +/- 0.06 VIP-ra vs 2.69 +/- 0.09 SP-ra vs 2.20 +/- 0.09 control, P < 0.01). MMCs returned 180 +/- 17 min in controls vs 99 +/- 14 min in VIP-ra-treated rats (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Efferent limb myoneural and luminal continuity and postgastrectomy gastric emptying.

Delayed gastric emptying and altered upper gut transit or both are common following Roux-en-Y gastrojejunostomy and are thought to be due to altered efferent limb transit secondary to isolation of the Roux limb from the duodenal pacemaker. We postulated that preservation of myoneural continuity of the Roux limb with the duodenal pacemaker would enhance solid gastric emptying, while division of the afferent limb of a Billroth II gastrojejunostomy (B-II), isolating the efferent jejunal limb from the duodenal pacemaker, would slow gastric emptying. Solid gastric emptying was measured in 14 dogs, who then underwent gastric vagotomy and antrectomy. Eight animals were reconstructed with a Roux-en-Y gastrojejunostomy, preserving myoneural but not luminal continuity of the Roux limb with the afferent limb via a muscularis bridge, while six dogs underwent standard B-II gastrojejunostomy. Serosal electrodes were placed on the afferent and efferent jejunal limbs. Gastric emptying was restudied, with fed and fasted myoelectric recordings. The bridge was then divided to create a standard Roux, while the afferent limb was transected and reanastomosed just proximal to the gastrojejunostomy in the B-II dogs to isolate the efferent limb from the duodenal pacemaker, with repeat studies. Bridge dogs had delayed solid gastric emptying compared to their preoperative state, despite normal efferent limb motility.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Roux-en-Y↗

PubMed1995

The effect of Roux-en-Y diversion on gastric and Roux-limb emptying in a rodent model.

BACKGROUND: The "Roux stasis syndrome" is characterized by symptoms of upper gut stasis following Roux-en-Y gastrojejunostomy (RG). Whether symptoms result from delayed gastric emptying, altered Roux-limb transit, or both has never been settled, partly because of the difficulty of measuring Roux-limb transit. The aim of this study was to develop a model to simultaneously quantitate Roux-limb transit and gastric emptying. METHODS: Rats underwent vagotomy and antrectomy with RG or Billroth II reconstruction (B-II). Gastrointestinal transit of a solid meal (Technetium-99m sulfur colloid-labelled egg white) was assessed 0.5, 1, and 1.5 hours postprandial (pp). Transit of a liquid marker (Na51-CrO4 injected through an efferent-limb catheter) was measured at 25 minutes pp. RESULTS: Solid gastric emptying was slower in RG than in B-II rats at 60 and 90 minutes pp. More of the solid meal and of the liquid marker was retained in the Roux limb than the efferent limb of the B-II at all time points (P < 0.05). CONCLUSIONS: In a rodent model, Roux-en-Y gastrojejunostomy is associated with delayed gastric emptying and slowed efferent-limb transit of solids and liquids.

Analysis of Variance↗

PubMed1994

Erythromycin enhances gastric emptying in patients with gastroparesis after vagotomy and antrectomy.

We studied the effect of erythromycin on gastric emptying in nine patients with gastroparesis following truncal vagotomy and antrectomy, and assessed their clinical response to chronic oral erythromycin. Gastric emptying was evaluated using a solid-phase radio-labeled meal. Patients were studied after erythromycin 200 mg intravenously (N = 9) and after an oral suspension of erythromycin 200 mg (N = 7) each given 15 min after ingestion of the meal. Three parameters of gastric emptying were analyzed: half-emptying time (T1/2), area under the curve, and percent gastric residual at 2 hr. Nine patients were subsequently placed on oral suspension erythromycin 150 mg three times a day before meals (range 125-250 mg three times a day) and symptoms of nausea, vomiting, postprandial fullness, and abdominal pain were assessed before and after erythromycin. Intravenous erythromycin markedly accelerated the gastric emptying (all three parameters studied) of solids (P < 0.01) in seven of nine patients with postsurgical gastroparesis [baseline T1/2 154 +/- 15 min; after intravenous erythromycin, T1/2 56 +/- 17 min (mean +/- SEM)]. Oral erythromycin enhanced (P < 0.05) the gastric emptying rate (T1/2, area under the curve) in five of seven patients (baseline T1/2 146 +/- 16 min; after oral erythromycin, T1/2 87 +/- 20 min). Of the nine patients who were placed on oral maintenance erythromycin, three showed clinical improvement after two weeks. In summary, erythromycin significantly enhances gastric emptying in many patients with vagotomy and antrectomy-induced gastroparesis; however, only a small subset of patients respond clinically to chronic oral erythromycin.

Administration, Oral↗

PubMed1993

Postoperative gastroparesis and tachygastria--response to electric stimulation and erythromycin.

BACKGROUND: The purpose of this study was to correlate clinical course, gastric emptying, and gastric myoelectric activity in a patient after gastric operation and to determine the effect of electric stimulation and the administration of erythromycin on the patient's gastric rhythm. METHODS: Daily myoelectric recordings were obtained through implanted gastric electrodes after truncal vagotomy and gastroenterostomy for an obstructing duodenal ulcer. RESULTS: The patient had acute postoperative delayed gastric emptying, accompanied initially by stomal edema but subsequently associated with persistent tachygastria. The gastric rhythm was only transiently slowed by multiple attempts at electroversion but appeared to respond dramatically to intravenous erythromycin therapy. Although delayed gastric emptying persisted on radionuclide gastric emptying studies, the patient slowly improved clinically with continued erythromycin therapy. CONCLUSIONS: Disturbances in gastric rhythm may accompany postoperative gastroparesis, although in our patient the dysrhythmias appeared to occur secondary to gastric outlet obstruction. Although his stomach could be paced, pacing was not effective in restoring a normal gastric rhythm. In contrast, intravenous erythromycin therapy was associated with rapid restoration of a normal gastric rhythm and slow improvement in gastric function.

Anastomosis, Surgical↗

PubMed1992

Does selective vagotomy prevent delayed gastric emptying and altered myoelectric activity following Roux-en-Y gastrojejunostomy?

Delayed gastric emptying occurs frequently following Roux-en-Y gastrojejunostomy. The role of vagal denervation in the etiology of this "Roux-stasis syndrome" is controversial. This study evaluates the effect of selective vagotomy on gastric emptying and motility following Roux-en-Y. Four dogs underwent control gastric emptying studies. The animals then underwent selective vagotomy, antrectomy, and Billroth II gastrojejunostomy, with placement of serosal electrodes. Gastric emptying was assessed with simultaneous myoelectric recordings, and the animals were converted to Roux-en-Y, followed by repeat studies. Gastric emptying was unchanged following selective vagotomy, antrectomy, and Billroth II gastrojejunostomy (T 1/2: 132 +/- 18 min [SEM] versus 118 +/- 14 min control) but was markedly delayed following Roux-en-Y diversion (T 1/2: 286 +/- 44 min; p less than 0.01). All animals went into the fed pattern following Billroth II gastrojejunostomy (migrating myoelectric complex [MMC] interval: 326 +/- 6 min postprandial versus 92 +/- 5 min fasting; p less than 0.01), but no fed pattern was recognized in three of four animals following Roux-en-Y diversion (MMC interval: 68 +/- 12 min postprandial versus 62 +/- 1.5 min fasting; p = NS). In a canine model, selective vagotomy does not prevent delayed gastric emptying or myoelectric alterations following Roux-en-Y.

Anastomosis, Roux-en-Y↗

PubMed1992

Human gastric myoelectric activity and gastric emptying following gastric surgery and with pacing.

Postoperative gastric myoelectric activity, gastric emptying, and clinical course were correlated in 17 patients at high risk of developing gastroparesis after gastric surgery. In addition, an attempt was made to pace the stomach with an electrical stimulus and determine the effect of pacing on early postoperative gastric emptying. Gastric dysrhythmias (bradygastria, slow wave frequency < 2 cycles/min; tachygastria, slow wave frequency > 4 cycles/min) persisted beyond the first postoperative day in 6 patients (35%). Delayed gastric emptying was identified by a radionuclide meal in 15 patients (88%), but symptoms of gastroparesis developed in only 6 of 15 (40%). Patients with postoperative gastroparesis had more frequent dysrhythmias than asymptomatic patients (67% vs. 18%), but these differences were not significant, although we cannot exclude a type II statistical error. Gastric rhythm was entrained in 10 of 16 patients (63%). Pacing increased the gastric slow wave frequency (3.1 vs. 4.1 cycles/min; P < 0.01) but did not improve gastric emptying (gastric retention at 60 minutes, 86% +/- 6% for control and 90% +/- 2% for paced). In conclusion, gastric dysrhythmias do not appear to play a major role in the development of postsurgical gastroparesis. Although gastric rhythm could be entrained in the majority of patients, pacing did not improve gastric emptying overall.

Adult↗

PubMed1992

Preoperative and postoperative motility disorders of the stomach.

Improved technology has expanded the study and understanding of gastrointestinal motility. Although no clear cause and effect relation has been demonstrated, altered motility has been found in association with a variety of nonsurgical and postoperative settings. As this relation is better defined, perhaps patients who are at risk to develop complications of surgery can be better identified so that treatment can be tailored toward their specific defect. Technological advances can also be expected to provide new and more effective interventions in this expanding field.

Anastomosis, Roux-en-Y↗

PubMed1992

Surgical approach to the obese patient.

Morbid obesity is a life-threatening disorder associated with medical and psychological complications. The failure of medical therapy has led to the development of a new surgical discipline called bariatric surgery, which has evolved over the past three decades. Initial techniques created malabsorption to produce weight loss. Due to complications, later techniques limited oral intake to produce weight loss. Currently, most bariatric surgeons perform either gastric bypass or gastric partition (vertical banded gastroplasty or vertical ring gastroplasty). However, other techniques are also being evaluated, including a modified intestinal bypass, gastric banding, and a new gastric balloon. Only with continued follow-up will we determine the ultimate risk/benefit ratio of these procedures and their place in the management of the morbidly obese. In the setting of an experienced multidisciplinary team committed to long-term follow-up, surgical therapy can be considered.

Gastric Bypass↗

PubMed1991

Pharmacokinetics of ranitidine after partial gastrectomy in dogs.

The effect of gastric surgery on the pharmacokinetics of ranitidine was studied in six dogs, all serving as their own controls. Prior to and after surgery, each dog received a single oral dose (5 mg/kg of body weight) of a ranitidine solution. The surgery consisted of partial gastrectomy (antrectomy) and truncal vagotomy. Ranitidine plasma and urine concentrations were measured by reversed-phase ion-pair liquid chromatography with UV detection. Pharmacokinetic parameters were estimated by noncompartmental data analysis techniques. Gastric surgery tended to slow the absorption of ranitidine as reflected by a slight increase of the time necessary to reach the peak plasma concentration. The maximum observed plasma concentration was slightly lowered. The amount of drug absorbed remained unchanged as reflected by no change in the AUCs. Other parameters such as mean residence time, elimination half-life, apparent oral clearance, and fraction excreted unchanged in the urine remained unchanged. However, due to the small number of animals and the considerable intersubject variability, none of these trends reached statistical significance.

Absorption↗

PubMed1991

Erythromycin enhances delayed gastric emptying in dogs after Roux-Y antrectomy.

Delayed gastric emptying occurs in up to 50% of patients after truncal vagotomy and Roux-Y antrectomy and is often resistant to nonsurgical therapy. This study evaluates the effect of erythromycin, metoclopramide, and motilin on delayed gastric emptying in four dogs after Roux-Y antrectomy. Solid food gastric emptying was measured using a radionuclide technique. Study groups were: (1) saline control; (2) erythromycin 1 mg/kg intravenously over 1 hour; (3) erythromycin 3 mg/kg by mouth 45 minutes prior to feeding; (4) metoclopramide 0.6 mg/kg intravenously over 1 hour; and (5) motilin 500 ng/kg intravenously over 1 hour. After Roux-Y antrectomy, saline control dogs had 73% +/- 5% (SEM) gastric retention at 2 hours. After intravenous and oral erythromycin, gastric emptying improved at 2 hours to 27% +/- 6% and 39% +/- 5% (p less than 0.01 compared with control). Erythromycin intravenously and by mouth improved gastric emptying compared with metoclopramide (64% +/- 8%, p less than 0.05). Motilin enhanced gastric emptying to a similar degree as erythromycin, with a 2-hour gastric retention of 37% +/- 4% (NS). Erythromycin improved gastric emptying in dogs with severe Roux-Y gastroparesis and may have clinical application.

Administration, Oral↗

PubMed1991

Erythromycin acts through a cholinergic pathway to improve canine-delayed gastric emptying following vagotomy and Roux-Y antrectomy.

We have demonstrated that erythromycin improves gastric emptying in dogs following truncal vagotomy and Roux-en-Y antrectomy (VRYA). To explore its mechanism of action we studied gastric emptying and myoelectric activity in a canine Roux model and administered atropine simultaneously with erythromycin. Tachyphylaxis was evaluated following short-term administration. Four dogs with delayed gastric emptying following VRYA were studied. Radionuclide solid gastric emptying was measured, with simultaneous myoelectric recordings obtained from the duodenum and Roux limb. Study groups were: (1) saline control (VRYA dogs); (2) erythromycin 1 mg/kg iv over 1 hr; (3) erythromycin 3 mg/kg po tid for 1 week, with repeat studies using erythromycin 1 mg/kg iv over 1 hr; and (4) atropine 0.5 mg/kg iv bolus, followed by a 1-hr infusion of atropine 0.05 mg/kg and erythromycin 1 mg/kg. Control Roux animals had severe gastric retention (73 +/- 5% at 2 hr, compared to 27 +/- 6% following iv erythromycin (P less than 0.01). Clustered spike bursts were observed in the Roux limb following erythromycin. Atropine abolished the gastrokinetic response and suppressed the myoelectric response to erythromycin (81 +/- 3% retention at 2 hr, P less than 0.01 compared to erythromycin alone). The response to erythromycin was unchanged after 1 week of tid administration (40 +/- 14% retention at 2 hr postprandial, P = NS). Erythromycin improves gastric emptying in VRYA dogs via a cholinergic pathway and does not exhibit tachyphylaxis following short-term administration.

Anastomosis, Roux-en-Y↗

PubMed1991

Antiperistaltic and isoperistaltic intussusception associated with abnormal motility after Roux-en-Y gastric bypass: a case report.

Antiperistaltic and recurrent intussusceptions are extremely rare in the adult. We report a patient with both. The patient developed an antiperistaltic intussusception distal to her Roux enteroenterostomy years after a Roux-en-Y gastric bypass for morbid obesity. The diagnosis was made preoperatively with gastrointestinal contrast radiography and ultrasonography. At surgery, the intussusception was reduced, and 12 inches of nonviable bowel was resected, with a functional end-to-end anastomosis. An isoperistaltic intussusception occurred in the early postoperative period just distal to the anastomosis. Manometric evaluation of the Roux limb after the second operation showed altered gastrointestinal motility, consisting of orad-propagated and aboard-propagated migrating motor complexes, minimal phase 2 activity, and lack of conversion to the fed pattern with a liquid meal. Although manometry was not performed before the development of the intussusception, our findings are consistent with the hypothesis that altered intestinal motility may contribute to the development of intussusception.

Adult↗

PubMed1991

Marginal ulcer following gastric bypass for morbid obesity.

Four hundred twelve patients underwent gastric bypass for treatment of morbid obesity between 1981 and 1985 at the University of Florida Affiliated Hospitals. Thirty-four patients (8.2%) developed marginal ulcers, considerably higher than the 0-3 per cent ulcer occurrence commonly reported in the literature. Factors predisposing to ulcer formation include: (1) a large gastric pouch; (2) a vertically oriented pouch; and (3) staple-line dehiscence. Twenty-two of 34 patients (65%) with symptomatic marginal ulcers were noted to have staple-line disruption. Twenty-one of these patients (95%) eventually required operative therapy for their ulcers compared with four of 12 patients (33%) with an intact gastric staple line. Surgical therapy consisted of takedown of the Roux-en-Y limb with resection of the ulcer and gastrogastrostomy. Staple-line dehiscence is a significant etiologic factor in the development of marginal ulcer following gastric bypass and when present constitutes an indication for reoperation.

Adolescent↗

PubMed1990

Effects of truncal vagotomy and partial gastrectomy on the pharmacokinetics of propranolol enantiomers in dogs.

The effect of partial gastrectomy on the pharmacokinetic parameters of (+)- and (-)-propranolol were investigated in six dogs. (+/-)-Propranolol (3 mg/kg body weight) was administered orally before and after surgery and the plasma concentrations of (+)- and (-)-propranolol were determined using an indirect enantioseparation technique. There were significant differences (p less than or equal to 0.05, paired t-test) in the area under the concentration-time curves (AUCs) and the maximum plasma concentration (Cmax) between (+)- and (-)-propranolol. The ratio AUC(+):AUC(-) was 1.73 +/- 0.28. These differences between the enantiomers remained unchanged after surgery. Other pharmacokinetic parameters showed no stereoselectivity. After partial gastrectomy, there was a slight, but nonsignificant decrease in time to reach maximum plasma concentration (tmax) and in the absorption half-life for both enantiomers. The maximum plasma concentration increased slightly. The elimination half-life and the mean residence time remained unchanged before and after surgery. Therefore, it is unlikely that there are any clinically relevant changes in the pharmacokinetics of (+)- and (-)-propranolol after partial gastrectomy.

Animals↗

PubMed1990

APUD update.

Apudomas are a diffuse group of tumors that have interested surgeons for a long time. With recent developments in their radiological localization and pharmacological control, they are now treated in a truly multidisciplinary approach. In this chapter, recent developments in the radiological, surgical, and medical approaches to these tumors are reviewed. Emphasis is placed on how non-surgical developments have affected the surgical treatment of specific apudomas. Resulting changes in surgical philosophy are also reviewed.

Apudoma↗

PubMed1990

Gastric dysrhythmias following pylorus-preserving pancreaticoduodenectomy. Possible mechanism for early delayed gastric emptying.

Transient delayed gastric emptying is reported as a frequent complication following pancreas-preserving pancreaticoduodenectomy (PPW). We placed serosal electrodes on the stomach of a patient undergoing PPW. Myoelectric recordings were obtained postoperatively and correlated with simultaneous radionuclide liquid gastric emptying studies. The patient developed early postoperative gastric atony, associated with frequent gastric dysrhythmias. These dysrhythmias may have been exacerbated by a perihepatic abscess. The gastric dysrhythmias correlated with alterations in liquid gastric emptying. Gastric dysrhythmias may be a mechanism for gastric dysfunction in the early postoperative period.

Adenocarcinoma↗

PubMed1990

Gastric emptying and myoelectric activity following Roux-en-Y gastrojejunostomy.

The purpose of this study was to compare gastric emptying and Roux myoelectric activity in a canine model. Four dogs underwent truncal vagotomy, antrectomy, and 40 cm Roux-en-Y gastrojejunostomy, with placement of serosal electrodes. Following recovery, gastric emptying was determined scintigraphically with a radiolabeled solid meal, and fasting and fed small-bowel myoelectric activity was obtained. Gastric emptying was markedly slowed compared to control unoperated animals (202 +/- 91 versus 46 +/- 12 min; P less than 0.05). Slow wave frequency declined in the Roux limb compared to the duodenum (14.2 +/- 0.4 versus 18.0 +/- .06 counts per minute; P less than 0.01). No gradient in slow wave frequency was observed in the Roux limb, although one animal was noted to have reversed propagation of slow waves in the proximal Roux limb. Migrating myoelectric complexes (MMCs) were coordinated between the Roux limb and jejunum distal to the enteroenterostomy, but not with the duodenum. Periodicity of the MMCs was different in the Roux limb and duodenum (98.6 +/- 6.3 versus 138 +/- 17.5 min; P less than 0.05). None of the animals converted to the fed myoelectric pattern with a 272 kcal meal (MMC periodicity in the Roux limb = 99 +/- 10 min postprandially, P = N.S.). These quantitative and qualitative alterations in myoelectric activity may contribute to the observed delay in gastric emptying following Roux-en-Y gastrojejunostomy.

Anastomosis, Roux-en-Y↗