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Biomedical subjects

T Simon

Publications and source records attributed to T Simon.

At least 55 records · Page 3Linked to original sources
PubMed2000

Naso-oesophageal probes decrease the frequency of sleep apnoeas in infants.

The objective of the study was to determine whether a naso-oesophageal probe modifies sleep and cardiorespiratory patterns in infants with repeated obstructive apnoeas. Two polygraphic recording sessions were conducted in random order for 2 nights on 35 infants suspected to have repeated obstructive sleep apnoeas. One sleep study was performed with a pH probe inserted through the nasal passage down to the distal portion of the oesophagus. The other session was conducted without any naso-oesophageal probe (the baseline study). For the 25 infants who presented repeated obstructive apnoeas during baseline studies, the presence of the probe was associated with a small, but significant, decrease in the number of central apnoeas (median frequency of 18.5 apnoeas per hour without a probe; 16.1 per hour with the probe; P=0.040), and obstructive apnoeas (median of 1.9 apnoeas per hour without a probe; 0.6 per hour with the probe; P=0.016). The presence of the probe was also associated with a small increase in percentage non-rapid eye movement (NREM) sleep frequency. The changes were statistically significant only for infants who had no obstructive apnoea during baseline studies (29 vs. 31%). The presence of a naso-oesophageal probe significantly modifies the infants' respiratory characteristics during sleep. These findings should be considered when reporting and interpreting sleep studies in infants.

Airway Obstruction↗
PubMed2000

Combined glutathione-S-transferase M1 and T1 genetic polymorphism and tacrine hepatotoxicity.

BACKGROUND: Glutathione conjugation of tacrine reactive metabolites depends in part on the activity of glutathione-S-transferases (GST), of which two isozymes (GST M1 and GST T1) are polymorphically expressed. OBJECTIVE AND METHODS: To determine whether GST M1, GST T1, and the combined GST M1 and GST T1 null genotypes predict individual susceptibility to tacrine hepatotoxicity, 141 patients with mild to moderate Alzheimer's disease treated with tacrine were genotyped. RESULTS: During the treatment period, 52 patients had elevated alanine aminotransferase (ALT) levels at least three times the upper limit of normal, whereas 89 patients had normal ALT values (< or = upper limit of normal). Both groups were comparable in demographic and clinical characteristics. Twenty-eight patients were found to be GST T1-negative (20%; with a 95% confidence interval [95% CI] from 13% to 27%), and 68 patients (48%; 95% CI from 40% to 57%) were GST M1-negative. The combined GST M1-T1 null genotype was observed in 18 patients (13%; 95% CI from 7% to 18%) of whom 13 had an elevated plasma ALT at least three times the upper limit of normal during the study period. Although the cumulative percentage of elevated plasma ALT tended to be higher in the GST M1 null genotype, neither GST M1 nor GST T1 alone could predict individual susceptibility to tacrine hepatotoxicity. Multivariate Cox hazards model showed that the association of the GST M1-T1 null genotype was an independent risk factor of hepatotoxicity. CONCLUSIONS: The presence of combined alleles M1 and T1 deficiencies in glutathione-S-transferase genes increases the susceptibility to tacrine hepatotoxicity.

Aged↗
PubMed2000

Hyperglycemia alone does not inhibit secretin-induced pancreatic bicarbonate secretion.

Administration of exogenous insulin (INS) inhibits secretin-stimulated pancreatic bicarbonate (HCO3) output via a dose-dependent, neurally mediated mechanism. To determine whether this effect was due to systemic hyperinsulinemia or to reduced endogenous insulin production, we examined the effect of hyperglycemia on secretin-stimulated pancreatic secretion. Chronic pancreatic fistulae were created in six dogs. After 30 minutes of equilibration, a computer-assisted hyperglycemic clamp protocol was used to maintain glucose (GLU) levels 100 or 150 mg/dL above basal in clamp animals; control animals received volume- and rate-matched infusions of 0.9% saline. One hour after beginning the clamp period, intravenous secretin dose-response (16-125 ng/kg/h) was begun, doubling the dose every half hour. Unstimulated (0-30 minutes) HCO3, GLU, and INS levels did not differ between groups. INS and GLU levels in clamp animals were significantly elevated during clamp (30-90 minutes) and stimulated (90-210 minutes) periods. For the same periods, HCO3 secretion was not significantly changed despite profound hyperinsulinemia. We conclude that systemic hyperinsulinemia alone does not inhibit secretin-stimulated HCO3 output. Since exogenous INS exerts feedback regulation on the pancreas, we propose that suppression of endogenous INS secretion mediates the previously reported inhibitory response.

Animals↗
PubMed2000

COX-2 inhibition with rofecoxib does not increase intestinal permeability in healthy subjects: a double blind crossover study comparing rofecoxib with placebo and indomethacin.

BACKGROUND: Acute and chronic use of non-steroidal anti-inflammatory drugs can increase intestinal permeability. Rofecoxib, which selectively inhibits cyclooxygenase 2 (COX-2), is a novel anti-inflammatory drug with the potential to produce minimal gastrointestinal toxic effects while retaining clinical efficacy. AIMS: To assess the potential for rofecoxib to affect the intestine adversely, in comparison with placebo and indomethacin. SUBJECTS: Thirty nine healthy subjects (aged 24-30 years). METHOD: We performed a four period crossover trial to assess intestinal permeability before and after seven days of treatment. Permeability was measured by the urinary ratio of chromium-51 labelled ethylene diamine tetraacetate ((51)CrEDTA)/L-rhamnose (five hour collection). RESULTS: Indomethacin 50 mg three times daily produced greater increases in intestinal permeability compared with placebo or rofecoxib (25 or 50 mg) (p< or = 0.001); rofecoxib was not significantly different from placebo. Mean day 7 to baseline ratios (95% confidence intervals) for (51)CrEDTA/L-rhamnose were 0.97 (0.82, 1.16), 0.80 (0.68, 0.95), 0.98 (0.82, 1.17), and 1.53 (1.27, 1.85) for placebo, rofecoxib 25 mg, rofecoxib 50 mg, and indomethacin groups, respectively. Rofecoxib was generally well tolerated. CONCLUSION: In this study, treatment for one week with indomethacin 50 mg three times daily significantly increased intestinal permeability compared with placebo, while treatment with rofecoxib 25 mg or 50 mg daily did not. The absence of a significant effect of rofecoxib on intestinal permeability at doses at least twice those recommended to treat osteoarthritis was consistent with other studies that have demonstrated little or no injury to the gastrointestinal mucosa associated with rofecoxib therapy.

Adolescent↗
PubMed1999

Experience with percutaneous transhepatic cholangioscopy (PTCS) in the management of biliary tract disease.

BACKGROUND: Biliary tract disorders often present significant management difficulties, particularly in patients who are poor surgical candidates. Percutaneous transhepatic cholangioscopy (PTCS) is an infrequently utilized alternative that might offer significant therapeutic benefit. We reviewed our experience with the use of this modality as a definitive therapy for biliary tract disorders. METHODS: Patient records at the Atlanta VAMC and Emory University hospitals were reviewed. We identified 17 patients who had undergone 25 PTCS interventions between August 1994 and December 1998. The indications for PTCS included dilatation of biliary-enteric anastomoses in four patients, biliary stone removal (with or without lithotripsy) in eight patients, stricturoplasty in four patients, biopsy of suspected biliary neoplasms in seven patients, and removal of obstructing clot in one patient. Most procedures (n = 17) were performed through percutaneous transhepatic tracts (12-18 Fr) that were <1 week old. All tracts were dilated to operating size on the day of the procedure. All patients received periprocedural antibiotics. RESULTS: The interventions were successful in seven of eight stone removals, four of five stricturoplasties, three of four anastomotic dilatations, seven of seven biopsies, and the single clot removal. The only complication involved one episode of hemobilia, requiring angio-embolization of a small branch of the right hepatic artery. CONCLUSIONS: PTCS is a safe, useful, and well-tolerated adjunct to the more common endoscopic and surgical techniques for managing complicated biliary tract disorders. Our experience suggests that PTCS can be performed early, without prolonged sequential dilatation of the percutaneous transhepatic tract, and may allow avoidance of operation in high-risk surgical candidates.

Adult↗
PubMed1999

Current management of endoscopic feeding tube dysfunction.

Surgically placed gastrostomy and jejunostomy feeding tubes allow administration of enteral nutrition for patients who are unable to swallow safely. Several endoscopic techniques have been used for tube placement. Endoscopically placed feeding tubes provide access to the gastrointestinal tract, but only when patent. Use of the approaches presented permits optimal feeding tube care and prolongs tube patency. Table 1 summarizes the recommendations for preventing and restoring patency to feeding tubes.

Adult↗
PubMed1999

A randomized trial comparing the effect of rofecoxib, a cyclooxygenase 2-specific inhibitor, with that of ibuprofen on the gastroduodenal mucosa of patients with osteoarthritis. Rofecoxib Osteoarthritis Endoscopy Study Group.

BACKGROUND & AIMS: Prostaglandin production in the normal gastrointestinal tract, believed to be critical for mucosal integrity, is mediated by cyclooxygenase (COX)-1, whereas prostaglandin production at inflammatory sites seems to occur via induction of COX-2. We hypothesized that COX-2-specific inhibition with rofecoxib (25 mg once daily) in the treatment of patients with osteoarthritis would cause fewer gastroduodenal ulcers than an equally effective dose of ibuprofen (800 mg 3 times a day), a nonspecific COX inhibitor. METHODS: A total of 742 osteoarthritis patients without ulcers on baseline endoscopy were randomly assigned to receive rofecoxib (25 or 50 mg once daily), ibuprofen (800 mg 3 times daily), or placebo. Endoscopy was repeated at 6, 12, and 24 weeks. At 16 weeks, by study design, 95% of the placebo group and 5% of the other groups were discontinued. RESULTS: The cumulative incidence of gastroduodenal ulcers >/=3 mm with rofecoxib (25 or 50 mg once daily) was significantly (P < 0.001) lower than with ibuprofen and was statistically equivalent to placebo at week 12 (placebo, 9.9%; 25 mg rofecoxib, 4.1%; 50 mg rofecoxib, 7.3%; and ibuprofen, 27.7%). At 24 weeks, ulcer rates were 25 mg rofecoxib, 9. 6%; 50 mg rofecoxib, 14.7%; and ibuprofen, 45.8% (P < 0.001, ibuprofen vs. 25 and 50 mg rofecoxib). CONCLUSIONS: Rofecoxib, at doses 2-4 times the dose demonstrated to relieve symptoms of osteoarthritis, caused significantly less gastroduodenal ulceration than ibuprofen, with ulcer rates comparable to placebo.

Aged↗
PubMed1998

Double-blind trial of omeprazole and amoxicillin in the cure of Helicobacter pylori infection in gastric ulcer patients. The Ulcer Study Group, Germany.

BACKGROUND: Our aim was to investigate the efficacy of omeprazole and amoxicillin in curing Helicobacter pylori infection in gastric ulcer patients. METHODS: In a double-blind trial 185 H. pylori-positive gastric ulcer patients were prospectively randomized to receive 40 mg omeprazole twice daily and either 750 mg amoxicillin three times daily or 750 mg amoxicillin placebo three times daily on days 1-14, followed by 20 mg omeprazole daily on days 15-56. RESULTS: Twenty-seven patients were excluded because of lack of compliance or missed follow-up examinations; one patient receiving amoxicillin discontinued treatment owing to side effects. On an intention-to-treat basis, omeprazole/amoxicillin led to cure of H. pylori infection in 67.1% (47 of 70) of patients not using non-steroidal anti-inflammatory drugs (NSAIDs)/aspirin (ASA) and in 46.7% (14 of 30) of those taking NSAIDs/ASA (P < 0.05). With the omeprazole/placebo regimen, H. pylori infection was cured in 8.8% (no NSAIDs), and 0% (NSAIDs). CONCLUSIONS: The use of NSAIDs/ASA may limit the efficacy of omeprazole/amoxicillin in curing H. pylori infection in gastric ulcer patients.

Adolescent↗
PubMed1998

Comparison of the angiotensin II receptor antagonist irbesartan with atenolol for treatment of hypertension.

In this multicenter, double-blind study, the antihypertensive efficacy and safety of irbesartan were compared with those of atenolol in patients with mild-to-moderate hypertension. Following a 4- to 5-week placebo lead-in period, 231 patients with seated diastolic blood pressure (SeDBP) 95-110 mmHg were randomized to irbesartan 75 mg or atenolol 50 mg once daily for 24 weeks. Doses were doubled at Week 6 for SeDBP > or = 90 mmHg. At Week 12, or anytime thereafter, doses were doubled for SeDBP > or = 90 mmHg if not done at Week 6, and hydrochlorothiazide and then nifedipine were added. Efficacy was determined by change from baseline in blood pressure and by therapeutic response rates. Safety was assessed by monitoring adverse events (AEs). Both treatments significantly lowered blood pressure from baseline. There were no significant differences between treatment groups with respect to blood pressure changes or therapeutic response. Atenolol significantly reduced seated heart rate compared with irbesartan at Week 12. The incidences of serious AEs and discontinuations due to AEs were approximately twice as high in the atenolol group compared with the irbesartan group. Thus, in comparison to atenolol, irbesartan < or = 150 mg provided at least equivalent blood pressure control while demonstrating an excellent safety and tolerability profile.

Adult↗
PubMed1997

Relevance of human papillomavirus screening in management of cervical intraepithelial neoplasia.

OBJECTIVE: To evaluate the utility of human papillomavirus detection in identifying women with abnormal Papanicolaou smears who can be safely followed up with cytologic study only, we conducted a study to determine the sensitivity, specificity, and negative and positive predictive values of a Food and Drug Administration-approved human papillomavirus test kit for detection of cervical intraepithelial neoplasia in colposcopically directed biopsy specimens. STUDY DESIGN: We enrolled women with abnormal Papanicolaou smears referred to a colposcopy clinic serving indigent patients. All 1128 women had a referral Papanicolaou smear, a clinic Papanicolaou smear, and a sample for human papillomavirus deoxyribonucleic acid test; 1075 underwent colposcopically directed biopsies and endocervical curettage. We used the HPV Profile kit for human papillomavirus testing. RESULTS: Of 486 women with low-grade squamous intraepithelial lesions on Papanicolaou smear, 35.4% had high-risk human papillomavirus deoxyribonucleic acid detected, and of 592 with high-grade lesions, 44.4% had high-risk human papillomavirus detected. Among 527 women with biopsy specimens showing cervical intraepithelial neoplasia and in 267 with cervical intraepithelial neoplasia grades 2 or 3, 38.7% and 56.2% had high-risk human papillomavirus deoxyribonucleic acid detected. However, the sensitivity of human papillomavirus deoxyribonucleic acid detection to identify biopsy-confirmed cervical intraepithelial neoplasia grades 2 or 3 was 55.7%, and the positive predictive value of the test was only 34.9%. CONCLUSION: Human papillomavirus appears to be causally associated with cervical cancer but human papillomavirus screening does not appear to be of value to identify women with abnormal Papanicolaou smears who can be safely followed up with cytologic study alone.

Adolescent↗
PubMed1996

Structural elements controlling anti-DNA antibody affinity and their relationship to anti-phosphorylcholine activity.

The heavy chains of the anti-DNA autoantibody D42, derived from an autoimmune NZB/NZW F1 mouse, and the anti-phosphorylcholine (PC) Ab 6G6, obtained from an immunized CBA/J mouse, are both encoded by the same VH11 (S107) germ-line gene. We have combined VH CDR3 exchange, site-directed mutagenesis, transfection of mutant hybridoma cells, and equilibrium affinity measurements of the expressed Abs to analyze the contribution of germ line-encoded genetic elements and somatic mutations to DNA binding affinity as well as to test the possibility that an anti-PC Ab can be converted to an anti-DNA Ab by somatic mutation. Our results indicate that the major contribution to DNA binding affinity is provided by the nonmutated rearranged configuration of the autoantibody and depends on the particular H/L chain pairing and the structure of the VH CDR3 gene segment. Two heavy chain somatic mutations increased the DNA binding affinity of the D42 anti-DNA Ab by about 10-fold. One of these mutations abolished PC binding of the 6G6 Ab, but did not convert it to an anti-DNA. These results suggest that activation of autoreactive B cells bearing germ-line-encoded Ag receptors may be required to initiate the affinity maturation of an anti-DNA response, and that B cells responding by somatic mutation to external Ags, such as PC, may be unable to contribute significantly to the high affinity immune response that is typical of disease-related anti-DNA autoantibodies.

Amino Acid Sequence↗