PubMed Health⌕ Search

Biomedical subjects

G O Barbezat

Publications and source records attributed to G O Barbezat.

At least 19 recordsLinked to original sources
PubMed2001

Somatostatin enhances cAMP-dependent short-circuit current in human colon via somatostatin receptor subtype-2.

Somatostatin inhibits colonic ion secretion in animal models and cultured intestinal cell lines via somatostatin receptor subtype 2 and subtype 1, respectively. In a recent in vitro ion transport study of the human colon, somatostatin was shown to stimulate short-circuit current, a measure of electrogenic ion transport. In this study we have used the reverse-transcription polymerase chain reaction (RT-PCR) and measurements of changes in short-circuit current (Isc) in response to receptor subtype-specific analogs of somatostatin, to define the somatostatin receptor subtype responsible for the stimulation of short-circuit current in human colon. Somatostatin receptor subtypes 1, 2, and 5, but not 3 and 4, were detected in the human colonic epithelium. Measurements of short-circuit current showed somatostatin and octreotide (1 micromol/liter) increased the prostaglandin stimulated short-circuit current by 12.3+/-1 and 11.0+/-1 microA/cm2, respectively. Similarly, analogs selective for somatostatin receptor subtypes 2 and 5 (1 micromol/liter) produced an increase of short-circuit current of 11.7+/-1 and 13.2+/-1 microA/cm2, respectively. However, at a concentration (10 nmol/liter) near the EC50, the somatostatin receptor subtype 2 analog increased short-circuit current by 9+/-1 microA/cm2, whereas the receptor subtype 5 analog had no effect. There was no difference in receptor expression or effect of the peptides related to the anatomical site of tissue collection. In conclusion, human colonic mucosa expresses multiple somatostatin receptor subtypes, of which subtype 2 mediates the stimulatory effect of somatostatin on ion transport.

Colon↗
PubMed2000

New treatment for Barrett's oesophagus.

Barrett's esophagus is characterised by the presence of specialised intestinal metaplasia in the lower esophagus. Its importance is related primarily to its link with adenocarcinoma of the lower esophagus, often preceded by dysplastic changes. The incidence of this carcinoma has increased dramatically over the last few decades. Although modern treatments, particularly acid suppression with proton pump inhibitors, have been most useful in controlling the reflux symptoms associated with Barrett's esophagus, they have not reduced the incidence of adenocarcinoma of the esophagus. The same can be said about anti-reflux surgery. Surgical excision of Barrett's esophagus has been advocated when high-grade dysplasia is detected; this carries considerable morbidity and mortality, so alternative treatments are being developed. This update summarises recent information concerning newer treatments aimed at eradicating Barrett's esophagus. These vary from thermal coagulation (using electrocoagulation and heater probes) to lasers, photodynamic therapy and mechanical methods. Of these, photodynamic therapy using a porphyrin precursor (5-amino-laevulinic acid) seems to give the most consistent satisfactory results with a minimum of complications. However, persistence of some metaplastic cells beneath the neo-squamous layer remains a problem. Ongoing effective acid control (by medical or surgical therapy) is also essential to prevent recurrence of Barrett's esophagus. Future research is aimed at perfecting these methods. Ultimately, it may be possible to understand the molecular biology which could help to predict which patients are at greatest risk of developing dysplastic and carcinomatous changes.

Barrett Esophagus↗
PubMed1999

Omeprazole therapy decreases the need for dilatation of peptic oesophageal strictures.

BACKGROUND: Better control of gastric acid secretion with omeprazole appeared to decrease the need for dilatation of oesophageal strictures complicating gastro-oesophageal reflux disease in our hospital-based endoscopy service. AIM: To investigate whether the perceived decrease in the need for oesophageal dilatation could be documented from endoscopy records, and, if confirmed, whether this could be related to the treatment used. PATIENTS AND METHODS: Retrospective study of the records of 69 patients who had peptic oesophageal strictures dilated, followed by treatment with acid inhibition for at least 6 months. Mean duration of follow-up was 3.9 years during treatment with H2-receptor antagonists and 2.1 years while on omeprazole (258 and 78 patient-years, respectively). Re-dilatation rates were compared between those treated with H2-receptor antagonists or omeprazole. RESULTS: There has been a significant decrease in dilatations performed for gastro-oesophageal reflux induced strictures (P<0.001), while dilatation rates for other indications remained constant. Treatment with omeprazole not only decreased the need for further dilatations, but also prolonged the mean time between any further dilatations to 26.3 months compared to 9.3 months for those on an H2-receptor antagonist (P<0.0001). CONCLUSIONS: Following dilatation of peptic oesophageal strictures, treatment with omeprazole in place of an H2-blocker significantly decreases the need for repeat dilatation.

Adult↗
PubMed1998

Seroprevalence of Helicobacter pylori in a longitudinal study of New Zealanders at ages 11 and 21.

BACKGROUND: Helicobacter pylori seroprevalence increases with age in adult life but spontaneous reversion may occur in childhood and adolescence. AIMS: To determine the seroprevalence of H. pylori in a longitudinal study of New Zealanders at ages 11 and 21. METHODS: Serum from members of the Dunedin Multidisciplinary Health and Development Study (DMHDS) at age 11 (n = 561; 303 males, 258 females) and 21 (n = 785; 413 males, 372 females) was tested for H. pylori antibodies. A large proportion of those tested at age 11 was retested at age 21 (n = 465; 262 males, 203 females). Serological status was examined in terms of gender, socioeconomic status (SES) and self-reported use of antibiotics. RESULTS: The seroprevalence of H. pylori decreased by 38% from 6.6% (37/561) at age 11 to 4.1% (32/785) at age 21. Seroprevalence at age 11 was not associated with gender or SES. For those tested at both ages, the drop in seroprevalence from 6.7% to 4.1% was statistically significant (t = 2.57, p < 0.01, paired t-test) and was much greater in females (71%) than males (12%). Of the 31 seropositive individuals at age 11, 17 (six males, 11 females) seroreverted and self-reported antibiotic use in the year preceeding age 21 was more common in females (eight/11) than males (zero/six). Of the 434 seronegative individuals at age 11, only five (four males, one female) had seroconverted at age 21. CONCLUSIONS: Seroprevalence in the DMHDS declined from age 11 to 21 predominantly in females. The decline involved a greater rate of seroreversion and lower rate of seroconversion in females than males.

Adolescent↗
PubMed1997

ERCP: a review of technical competency and workload in a small unit.

BACKGROUND: ERCP is increasingly performed not only in large referral centers but also in smaller units. We sought to analyze the success rates of selective cannulation and intervention using the cumulative sum method and to document the workload in a small unit. METHODS: Indications, results, and interventions performed by one endoscopist were recorded for all patients undergoing ERCP at Dunedin Hospital. Selective cannulation and successful intervention were used as outcome measures and, using the cumulative sum method, compared to a target value of 90%. RESULTS: Over an 8-year period, 532 ERCPs were performed. Overall 91% and 81% of selective cannulation and interventions respectively, were successful. The cumulative sum method plot shows that satisfactory outcomes for selective cannulation were obtained after some 100 to 120 procedures and after some 120 interventions. ERCP was normal in 171 (32%) patients, stones were found in 169 (32%), and strictures in 81 (15%) patients. CONCLUSIONS: The cumulative sum method is a valuable tool to compare individual performance with a nominated target value and to ensure that an acceptable outcome is achieved and maintained. These results show that small units can develop and maintain expertise in ERCP if procedures are performed regularly.

Adolescent↗
PubMed1996

Seroprevalence of Helicobacter pylori in a birth cohort of 21-year-old New Zealanders.

OBJECTIVE: To determine the seroprevalence of Helicobacter pylori (H. pylori) in a subset of a birth cohort of New Zealanders at age 21 and examine the association with risk factors and digestion-related symptoms. DESIGN: Assay of serum collected from members of a longitudinal study during 1993-94 and a survey of risk factors and digestion-related symptoms by interview and questionnaire. METHODS: Serum from 785 sample members (413 males, 372 females) of the 950 participating in the Dunedin Multidisciplinary Health and Development Study (DMHDS) at age 21 was analysed for H. pylori antibodies. Serum samples (n = 579) from the cohort at age 11 collected in 1983 were analysed for those who were seropositive at age 21. RESULTS: The seroprevalence of H. pylori at age 21 was 4.1% (32/785), with proportionally more males in the seropositive group (chi 2 = 6.7, P < 0.01). Serum samples taken at age 11 were available for 19 of the seropositive group and 74% of these (11 males, three females) were seropositive. The seropositive group at age 21 was no different in the size of their families, but at age 5 contained proportionally more individuals from families of low socioeconomic status (SES) (chi 2 = 6.1, P < 0.05). There was no difference between the two groups in terms of upper gastrointestinal tract symptoms, recent use of medications, smoking or alcohol consumption. CONCLUSION: The seroprevalence of H. pylori among a birth cohort of 21-year-old New Zealanders is significantly lower than among most populations of about the same age in other countries. Seropositivity is higher in males and among families of lower SES, and is not associated with digestion-related symptoms. The seroconversion rate after age 11 appears to be low.

Adult↗
PubMed1995

Expression of somatostatin receptor genes and their role in inhibiting Cl- secretion in HT-29cl.19A colonocytes.

Recent studies in a cultured model of the intestinal epithelium (HT-29cl.19A) have shown that somatostatin-14 (SS-14) inhibits the Cl- secretory process by acting at multiple G protein-dependent sites. These actions may underlie the antidiarrheal properties of SS peptides. This study has investigated the expression of specific SS receptor subtypes (SSTR) in HT-29cl.19A and examined their role in mediating SS antisecretory actions. Two predominant SSTR, SSTR1 and SSTR2, were identified by reverse transcriptase-polymerase chain reaction (RT-PCR) of mRNA from polarized HT-29cl.19A monolayers. Receptor binding studies showed evidence of two distinct populations of binding sites consistent with the known properties of SSTR1 and SSTR2. The role of SSTR in inhibition of secretion was investigated by comparing the effectiveness of native and synthetic SS peptides on adenosine 3',5'-cyclic monophosphate (cAMP)-dependent Cl- secretion. Secretion stimulated by the receptor-mediated agonist prostaglandin E2 (PGE2) was inhibited > 70% by SS-14 with a 50% effective concentration (EC50) of 32 nM. In contrast, SMS-201-995 (SMS) and RC-160 exhibited little or no antisecretory activity (maximum inhibition of 15 +/- 1.9 and 2.8 +/- 1.9%, respectively, at 100 microM; EC50 > 1.5 microM). Similar effects on PGE2-stimulated cAMP accumulation were also observed. SS-14, but not SMS, also inhibited secretion stimulated by dibutyryl cAMP, which acts independently of changes in cellular cAMP. Pretreatment with pertussis toxin reversed the antisecretory effects of SS peptides.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1995

Flexible sigmoidoscopy or colonoscopy for colorectal screening: a randomized trial of performance and acceptability.

In a randomized clinical trail to assess acceptability, yields, costs, and unwanted effects of screening procedures, 232 subjects (137 with family history of colorectal carcinoma or adenoma, 95 without) were offered either flexible sigmoidoscopy or colonoscopy. Subjects with polyps found on sigmoidoscopy were followed up by colonoscopy. The two procedures were similar in compliance (65%) and yield (19% adenoma, 15% hyperplastic polyps). Polyps of either type were more common in those with a family history (prevalence: 41% compared with 24% without family history, p = 0.04). Costs per procedure were 60% lower for sigmoidoscopy, but follow-up colonoscopy reduced this cost advantage to 20% per subject. The subjects found the preparation for sigmoidoscopy easier, but the procedure more uncomfortable and embarrassing, as colonoscopy was performed under sedation. In this hospital-based study, colonoscopy was as acceptable to subjects, and only slightly more costly than sigmoidoscopy. Advantages of sigmoidoscopy would be greater for use outside hospitals and with less intensive follow up.

Aged↗
PubMed1992

Impaired intestinal electrolyte transport in rats infested with the common parasite Syphacia muris.

An incidentally discovered infestation with the nematode Syphacia muris of cecum and colon in spontaneously hypertensive (SHR) and normotensive control (WKY) rats was investigated over a two-year period. Infestation rates in WKY were higher than in SHR, while clinical signs as well as histological changes of colonic tissues were absent in both strains. In vivo net water absorption (microliter/hr/cm2) in control worm-free SHR turned into secretion in infested rats, ie, from 74.2 +/- 23.2 to -7.5 +/- 35.0 (P less than 0.001); this corresponded with a decrease in net absorption (mumol/hr/cm2) of Na from 18.5 +/- 2.4 to 9.3 +/- 4.3 (P less than 0.001) and of Cl from 14.0 +/- 3.2 to 3.2 +/- 5.7 (P less than 0.001). In WKY, net water absorption decreased from 112.2 +/- 23.2 to 48.0 +/- 25.1 (P less than 0.001) and Na and Cl absorption from 22.3 +/- 3.1 to 16.0 +/- 4.2 (P less than 0.005) and from 19.4 +/- 2.7 to 10.9 +/- 4.7 (P less than 0.005), respectively. Antihelminthic treatment with 0.007% pyrvinium pamoate in the ration (four weeks on, six months off) eradicated Syphacia muris in both rat strains. Body weight gain of young rats on normal and pyrvinium pamoate-substituted diet studied over 18 months was similar, indicating a good tolerance of the treatment. It is concluded that results obtained during comparative intestinal transport studies between SHR and WKY may not only be impaired but also significantly distorted by Syphacia muris infestation as SHR appear to be more susceptible to effects induced by this common parasite than WKY.

Animals↗
PubMed1991

Lactose malabsorption and calcium intake as risk factors for osteoporosis in elderly New Zealand women.

OBJECTS: to evaluate the prevalence of lactose malabsorption and to assess dietary calcium intake, in elderly New Zealand women with hip fractures, in age matched case controls without hip fractures drawn from general practice, and in healthy young women. METHODS: lactose malabsorption was assessed by measuring breath hydrogen after a 50 g oral lactose tolerance test. Dietary calcium was estimated from a food frequency questionnaire. RESULTS: the elderly fracture cases (n = 15), and their elderly controls (n = 16), showed a similar (60% and 63% respectively), but significantly higher prevalence (p less than 0.001), of lactose malabsorption than young women (12%, n = 50). Dietary calcium intake was similar in lactose absorbers and malabsorbers. CONCLUSIONS: malabsorption of lactose occurs commonly in elderly New Zealand women but is scarce in young adults. A high prevalence of lactose malabsorption may be a risk factor for exacerbation of type II osteoporosis in the elderly.

Adolescent↗
PubMed1991

[Ultrasonic study of gastric emptying of various oral rehydration solutions].

Gastric emptying of 4 different oral rehydration solutions was investigated by ultrasound in 7 healthy volunteers in a randomized double-blind study. The final gastric emptying times were 32.9 +/- 4.72 minutes for the glycine solution, 55.1 +/- 9.85 minutes for the glucose (WHO) solution. 60.8 +/- 11.58 minutes for the polycose solution and 58.6 +/- 10.12 minutes for the rice-flour solution (p less than 0.05). Gastric emptying times showed considerable person-to-person variability. Based on identical gallbladder volumes before and 60 minutes after ingestion of the rehydration solutions, there was no indication of cholecystokinin stimulation by any of the solutions tested.

Adult↗
PubMed1991

Only pharmacological doses of atrial natriuretic peptide affect intestinal ion transport in non-volume expanded rats.

Pharmacological doses of atrial natriuretic peptide were infused into rats to study its effect on intestinal transport. Saline control or two concentrations of rat alpha atrial natriuretic peptide (0.06 or 1.0 nmol/min/kg) were administered intravenously (1 ml) over one hour. Jejunal net transport of water and electrolytes was measured with a plasma-like luminal electrolyte solution using a 'closed loop' technique. Distal colonic potential difference and arterial blood pressure were monitored continuously. Blood samples for analysis of plasma atrial natriuretic peptide concentrations were taken at the end of the experiments. Plasma concentrations were increased (mean (SD) (2.1 (0.5) and 24.0 (1.1) nmol/l respectively) compared with the controls (0.023 (0.016) nmol/l). Blood pressure dropped by 30% (p less than 0.05) in both groups of rats receiving atrial natriuretic peptide but remained unchanged when control saline was infused. Jejunal net absorption was reduced (p less than 0.01) only in animals receiving the higher concentration of peptide (H2O from 173 (33) to 64 (69) microliters.h-1.cm-2, Na from 25.7 (5.3) to 10.9 (8.9) mumol.h-1.cm-2). Distal colonic potential difference was not affected by atrial natriuretic peptide. In conclusion massive doses of atrial natriuretic peptide are required to produce any change in intestinal salt and water transport in normal, non-volume expanded rats; these effects could be a non-specific or 'toxic' response.

Animals↗
PubMed1991

Atrial natriuretic peptide and water and electrolyte transport in the human jejunum.

The effects of atrial natriuretic peptide were investigated on water and electrolyte transport in the human jejunum. Six healthy male volunteers (aged 21-33 years) were studied using a triple lumen perfusion technique. A plasma like electrolyte solution containing polyethylene glycol (5 milligrams) as a non-absorbable marker was perfused into the jejunum at 10 ml/min, and net water and electrolyte transport and transepithelial potential difference were measured. Subjects were studied single blind on two occasions with either intravenous atrial natriuretic peptide (6 pmol/min/kg for 90 minutes) or placebo (saline), both after controlled sodium intake over three days. Plasma atrial natriuretic peptide concentrations rose from (mean (SD)) 10.3 (3.6) pmol/l to a peak of 96.0 (61.8) pmol/l. Jejunal net water and electrolyte fluxes and potential difference were identical in both the atrial natriuretic peptide and the control studies. Compared with placebo atrial natriuretic peptide induced a significantly greater diuresis (peak 10.2 (6.0) v 1.8 (1.0) ml/min, p less than 0.05) and natriuresis (peak 1069 (351) v 376 (208) mumol/min, p less than 0.01) and haemoconcentration (haematocrit 0.405 (0.040) v 0.368 (0.018), p less than 0.01). There was no difference in blood pressure, pulse rate, plasma electrolytes, and plasma osmolality between the two studies. There was no evidence to suggest an effect of atrial natriuretic peptide on jejunal water and electrolyte transport in healthy human subjects.

Adult↗