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Biomedical subjects

D E Jennings

Publications and source records attributed to D E Jennings.

At least 19 recordsLinked to original sources
PubMed2005

Titan's atmospheric temperatures, winds, and composition.

Temperatures obtained from early Cassini infrared observations of Titan show a stratopause at an altitude of 310 kilometers (and 186 kelvin at 15 degrees S). Stratospheric temperatures are coldest in the winter northern hemisphere, with zonal winds reaching 160 meters per second. The concentrations of several stratospheric organic compounds are enhanced at mid- and high northern latitudes, and the strong zonal winds may inhibit mixing between these latitudes and the rest of Titan. Above the south pole, temperatures in the stratosphere are 4 to 5 kelvin cooler than at the equator. The stratospheric mole fractions of methane and carbon monoxide are (1.6 +/- 0.5) x 10(-2) and (4.5 +/- 1.5) x 10(-5), respectively.

Atmosphere↗
PubMed2004

Temperatures, winds, and composition in the saturnian system.

Stratospheric temperatures on Saturn imply a strong decay of the equatorial winds with altitude. If the decrease in winds reported from recent Hubble Space Telescope images is not a temporal change, then the features tracked must have been at least 130 kilometers higher than in earlier studies. Saturn's south polar stratosphere is warmer than predicted from simple radiative models. The C/H ratio on Saturn is seven times solar, twice Jupiter's. Saturn's ring temperatures have radial variations down to the smallest scale resolved (100 kilometers). Diurnal surface temperature variations on Phoebe suggest a more porous regolith than on the jovian satellites.

Atmosphere↗
PubMed2004

Jupiter's atmospheric composition from the Cassini thermal infrared spectroscopy experiment.

The Composite Infrared Spectrometer observed Jupiter in the thermal infrared during the swing-by of the Cassini spacecraft. Results include the detection of two new stratospheric species, the methyl radical and diacetylene, gaseous species present in the north and south auroral infrared hot spots; determination of the variations with latitude of acetylene and ethane, the latter a tracer of atmospheric motion; observations of unexpected spatial distributions of carbon dioxide and hydrogen cyanide, both considered to be products of comet Shoemaker-Levy 9 impacts; characterization of the morphology of the auroral infrared hot spot acetylene emission; and a new evaluation of the energetics of the northern auroral infrared hot spot.

Acetylene↗
PubMed2004

An intense stratospheric jet on Jupiter.

The Earth's equatorial stratosphere shows oscillations in which the east-west winds reverse direction and the temperatures change cyclically with a period of about two years. This phenomenon, called the quasi-biennial oscillation, also affects the dynamics of the mid- and high-latitude stratosphere and weather in the lower atmosphere. Ground-based observations have suggested that similar temperature oscillations (with a 4-5-yr cycle) occur on Jupiter, but these data suffer from poor vertical resolution and Jupiter's stratospheric wind velocities have not yet been determined. Here we report maps of temperatures and winds with high spatial resolution, obtained from spacecraft measurements of infrared spectra of Jupiter's stratosphere. We find an intense, high-altitude equatorial jet with a speed of approximately 140 m s(-1), whose spatial structure resembles that of a quasi-quadrennial oscillation. Wave activity in the stratosphere also appears analogous to that occurring on Earth. A strong interaction between Jupiter and its plasma environment produces hot spots in its upper atmosphere and stratosphere near its poles, and the temperature maps define the penetration of the hot spots into the stratosphere.

Journal Article↗
PubMed2001

Duration of effect of lansoprazole on gastric pH and acid secretion in normal male volunteers.

AIM: A double-blind, placebo-controlled study to assess the duration of effect of lansoprazole 30 mg o.m. on intragastric pH, acid secretion, gastrin levels, the potential for rebound acidity, and the relationship between gastric acid and drug pharmacokinetic parameters. METHODS: Sixteen subjects were treated with lansoprazole 30 mg daily or placebo for 14 days, followed by a 7-day post-dosing period and a post-study evaluation on day 28. Ambulatory 24-h pH was recorded and pentagastrin-stimulated acid secretion measured. Plasma kinetics of lansoprazole were determined. RESULTS: Mean intragastric pH in the lansoprazole group increased significantly (P < 0.05) from baseline to day 14 compared to placebo. After cessation of treatment, secretory activity, as measured by intragastric pH, basal acid output and stimulated acid output, returned to baseline in 2 to 4 days without any overshoot, indicating the absence of acid rebound. Lansoprazole's terminal disposition half-life was 1.11 h. Mean pH and serum gastrin returned to baseline with half-lives of 22 and 19 h, respectively. CONCLUSIONS: Lansoprazole 30 mg daily significantly increases mean intragastric pH without producing acid rebound. Regeneration of acid production depends primarily on de novo synthesis of the acid pump.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1999

Double-blind comparison of lansoprazole 15 mg, lansoprazole 30 mg and placebo as maintenance therapy in patients with healed duodenal ulcers resistant to H2-receptor antagonists.

BACKGROUND: Maintenance antisecretory therapy is often used to prevent duodenal ulcer recurrence and control symptoms. This study compared the efficacy and safety of lansoprazole 15 mg and 30 mg daily with placebo in preventing ulcer recurrence in patients with a recent history of duodenal ulcer disease. METHODS: Fifty-six patients were treated with either lansoprazole 15 mg, 30 mg or placebo o.m. RESULTS: Within 1 month of study initiation, 27% (four out of 15) of placebo-treated patients experienced ulcer recurrence as compared to 13% (two out of 15) and 6% (one out of 18) of lansoprazole 15 mg and 30 mg treated patients, respectively. Median time to first ulcer recurrence was > 12 months in lansoprazole patients. At Month 12, significantly (P < 0.001) more lansoprazole 15 mg patients (70%) and lansoprazole 30 mg patients (85%) remained healed. Eighty-two per cent of lansoprazole 15 mg and 76% of lansoprazole 30 mg patients remained asymptomatic during the entire study period. All placebo patients became symptomatic, experienced ulcer recurrence, or withdrew from the study by month six. The incidence of adverse events was comparable among the three treatment groups. CONCLUSIONS: Lansoprazole safely and effectively reduces duodenal ulcer recurrence and ulcer-related symptoms.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1998

Water in Betelgeuse and Antares.

Absorption lines of hot water have been identified in the infrared spectra of Betelgeuse (alpha Orionis) and Antares (alpha Scorpii) near 12.3 micrometers (811 to 819 wavenumbers). The water lines originate in the atmospheres of the stars, not in their circumstellar material. The spectra are similar in structure to umbral sunspot spectra. Pure rotation water lines of this type will occur throughout the spectra of cool stars at wavelengths greater than 10 micrometers. From the water spectra, the upper limit for the temperature in the line formation region in both stars is 2800 kelvin. The water column density in both stars is (3 +/- 2) x 10(18) molecules per square centimeter, yielding an abundance relative to atomic hydrogen of n(H2O)/n(H) approximately 10(-)7.

Astronomical Phenomena↗
PubMed1998

Observations of CH4, C2H6, and C2H2 in the stratosphere of Jupiter.

We have performed high-resolution spectral observations at mid-infrared wavelengths of CH4 (8.14 micrometers), C2H6 (12.16 micrometers), and C2H2 (13.45 micrometers) on Jupiter. These emission features probe the stratosphere of the planet and provide information on the carbon-based photochemical processes taking place in that region of the atmosphere. The observations were performed using our cryogenic echelle spectrometer CELESTE, in conjunction with the McMath-Pierce 1.5-m solar telescope between November 1994 and February 1995. We used the methane observations to derive the temperature profile of the jovian atmosphere in the 1-10 mbar region of the stratosphere. This profile was then used in conjunction with height-dependent mixing ratios of each hydrocarbon to determine global abundances for ethane and acetylene. The resulting mixing ratios are 3.9(+1.9)(-1.3) x 10(-6) for C2H6 (5 mbar pressure level), and 2.3 +/- 0.5 x 10(-8) for C2H2 (8 mbar pressure level), where the quoted uncertainties are derived from model variations in the temperature profile which match the methane observation uncertainties.

Acetylene↗
PubMed1998

Double-blind comparison of lansoprazole 15 mg, lansoprazole 30 mg, and placebo in the maintenance of healed gastric ulcer.

Our purpose was to compare the safety and efficacy of lansoprazole 15 mg and 30 mg with placebo in preventing recurrence in 49 patients with a history of gastric ulcer. Within one month, 40% of patients receiving placebo experienced ulcer recurrence compared to 0% and 7% of patients receiving lansoprazole 15 mg and 30 mg, respectively. All placebo patients became symptomatic, experienced ulcer recurrence or withdrew from the study by month 9. As compared to placebo, a significantly (P < 0.001) higher percentage of patients treated with lansoprazole 15 mg (83%) and lansoprazole 30 mg (93%) with healed gastric ulcer disease remained healed at month 12. Of patients asymptomatic at baseline, 100% and 59% of those treated with lansoprazole 15 mg and 30 mg, respectively, remained asymptomatic at month 12. The incidence of adverse events was comparable among the treatment groups. Lansoprazole safely and effectively reduces ulcer recurrence in patients with a history of gastric ulcer disease.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1998

Dose-response relationship of lansoprazole to gastric acid antisecretory effects.

BACKGROUND: Proton pump inhibitors have been found to be effective in numerous studies in patients with peptic ulcer disease, particularly associated with Helicobacter pylori and gastro-oesophogeal reflux disorders. Optimal healing rates of antisecretory therapy for peptic acid disease is dependent upon the degree and duration of acid suppression and the length of treatment. OBJECTIVE: To evaluate the extent and duration of gastric acid suppression of several lansoprazole regimens, administered for 5 consecutive days in 32 healthy adult male subjects. METHODS: Intragastric 24-h pH monitoring was performed in 32 healthy subjects in a randomized, double-blind, four-way crossover study. Sixteen subjects (Group 1) received lansoprazole 30 mg o.d. (once daily), 15 mg b.d. (twice daily), 30 mg b.d. and 30 mg t.d.s. (three times a day) for 5 days; and 16 subjects (Group 2) received lansoprazole 30 mg o.d., 60 mg o.d., 60 mg b.d. and 60 mg t.d.s. for 5 days. RESULTS: Mean 24-h intragastric pH values for lansoprazole 30 mg o.d., 15 mg b.d., 30 mg b.d. and 30 mg t.d.s. were 4.47, 4.57, 5.07 and 5.63, respectively. Multiple-dose regimens of lansoprazole 30 mg b.d. and t.d.s. produced greater acid suppression compared to lansoprazole 30 mg o.d. and 15 mg b.d. There was no significant difference in acid suppression between lansoprazole 30 mg o.d. and 15 mg b.d. Mean 24-h intragastric pH values for lansoprazole 30 mg o.d., 60 mg o.d., 60 mg b.d. and 60 mg t.d.s. were 4.13, 4.45, 5.19 and 5.13, respectively. Multiple-dose regimens of lansoprazole 60 mg b.d. and t.d.s. produced significantly greater acid suppression compared to lansoprazole 30 mg o.d. and 60 mg o.d. There was no significant difference in acid suppression between lansoprazole 30 mg o.d. and 60 mg o.d. Lansoprazole 30 mg t.d.s., 60 mg b.d. and 60 mg t.d.s. produced significantly greater percentage time above pH 3, 4, 5 and 6 than did lansoprazole 30 mg o.d. Post-regimen serum gastrin values increased by 50-130% from pre-study mean values but remained within normal range and returned to pre-study values 7-14 days post-dosing. CONCLUSIONS: Multiple-dose regimens of lansoprazole (> or =30 mg b.d. for 5 days) produce significantly increased intragastric pH and significantly longer duration of increased intragastric pH than does lansoprazole 30 mg administered once daily.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1998

A placebo-controlled dose-ranging study of lansoprazole in the management of reflux esophagitis.

OBJECTIVE: We compared the efficacy of three different doses of the proton pump inhibitor lansoprazole in the management of reflux esophagitis. METHODS: Two hundred ninety-two patients with endoscopically confirmed reflux esophagitis were enrolled in a double-blind, multicenter study and were randomized to lansoprazole 15, 30, or 60 mg or placebo administered once daily for 8 wk. RESULTS: Healing rates after 4 wk of lansoprazole 15, 30, and 60 mg/d were 67.6%, 81.3%, and 80.6%, respectively. These were all significantly superior (p < 0.001) to placebo, which produced endoscopic healing in only 32.8% of the patients after 4 wk. The 4-wk healing rates with lansoprazole 30 or 60 mg were significantly higher than that with lansoprazole 15 mg (p < 0.05), confirming a dose-response effect. Cumulative healing rates after 8 wk of treatment were 52.5% with placebo and 90.0%, 95.4%, and 94.4% with lansoprazole 15, 30, and 60 mg, respectively (p < 0.001 for all doses of lansoprazole vs placebo). Lansoprazole was also significantly superior to placebo in relieving symptoms in patients with reflux esophagitis. Lansoprazole was well tolerated, and no serious treatment-related adverse events were encountered. Up to 3 months after discontinuation of treatment, all lansoprazole-treated groups had more patients free of endoscopic evidence of esophagitis than the group treated with placebo. CONCLUSIONS: Lansoprazole was safe and effective for the treatment of reflux esophagitis in this trial. This study indicates that the optimum daily dose of lansoprazole for reflux esophagitis is 30 mg.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1997

The effects of oral doses of lansoprazole and omeprazole on gastric pH.

We compared gastric pH values after therapeutic doses of lansoprazole and omeprazole in 17 healthy adult men. The pharmacokinetics of the two drugs were studied. A three-way crossover design compared the effects on gastric pH of 15 and 30 mg lansoprazole and 20 mg omeprazole--each given once daily for 5 days. Ambulatory 24-h intragastric pH levels were measured before dosing, after the first and fifth doses in each period, and 15 days after each dosing period. A positive relationship between the lansoprazole or omeprazole area under the curve (AUCs) and the 24-h mean pH values was found for each regimen. No differences in maximum concentration (Cmax) and AUC were noted from day 1 to day 5 for the two lansoprazole doses. With omeprazole, both Cmax and AUC levels were greater on day 5 than on day 1. All three regimens increased 24-h mean gastric pH, although 30 mg lansoprazole had the most significant effect. The percentage of time that gastric pH was >3, >4, and >5 was also significantly higher with 30 mg lansoprazole. All three regimens were associated with reversible elevations of serum gastrin, which more than doubled at some points. No clinically significant adverse events were documented.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1995

A comparison of lansoprazole and ranitidine in the treatment of erosive oesophagitis. Multicentre Investigational Group.

BACKGROUND: Lansoprazole is a new proton pump inhibitor which produces prolonged decrease of gastric acidity. The aim of this study was to compare lansoprazole to a standard dose of ranitidine in the treatment of patients with reflux oesophagitis. METHODS: Two hundred and forty-seven patients with erosive oesophagitis were randomly assigned to 8 weeks of treatment with either 30 mg lansoprazole once daily or 150 mg ranitidine twice daily. RESULTS: Two hundred and forty-two patients were included in the analysis. Lansoprazole (30 mg) daily, healed oesophagitis in 92.1% of patients after 8 weeks of treatment. This was significantly superior to 150 mg ranitidine b.d.s. which healed oesophagitis in 69.9% of patients (P < 0.001). Relief of reflux symptoms was superior with lansoprazole to that with ranitidine. Both lansoprazole and ranitidine were well tolerated with no serious drug-related adverse events noted. CONCLUSION: Lansoprazole, 30 mg once daily, is highly effective and safe in the short-term treatment of erosive oesophagitis.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1995

A comparison of three doses of lansoprazole (15, 30 and 60 mg) and placebo in the treatment of duodenal ulcer. The Lansoprazole Study Group.

BACKGROUND: Lansoprazole is a new proton pump inhibitor for the treatment of peptic ulcer disease. METHODS: A double-blind, multicentre study was undertaken in 296 patients with endoscopically proven duodenal ulcer to compare the efficacy and safety of lansoprazole 15, 30 or 60 mg with placebo. Ulcer healing was documented by endoscopy at 2 and 4 weeks; patients whose ulcers healed after 4 weeks were followed for up to 6 months post-treatment. RESULTS: Four-week healing rates of 89.4%, 91.7% and 89.9% were obtained with lansoprazole 15, 30 and 60 mg, respectively, compared with 46.1% on placebo (P < 0.001). All three doses of lansoprazole produced rapid symptom relief, although patients taking 60 mg lansoprazole required fewer antacids than did those taking 15 mg. At 6 months, the percentages of patients healed were 45.3%, 40.0% and 38.4% in the lansoprazole 15, 30 and 60 mg dosage groups, respectively, and 25.3% for the placebo group. No significant adverse events were documented during the period of this trial. CONCLUSION: Lansoprazole is an effective and safe treatment for duodenal ulcer and the 15 mg dose is as effective as 30 or 60 mg.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1994

Platelet ultrastructure of high-risk premature infants.

Hemorrhagic and thrombotic complications are common in the term and preterm infant. Limited information is currently available about neonatal platelet structure and function, and how these may predispose infants to bleeding problems. This study comparing platelet ultrastructure of 71 different term and preterm infants with that of 15 adult control subjects revealed certain platelet morphological differences. Specifically, the adult platelets had more pseudopods, larger glycogen deposits, more visible microtubular structure, markedly fewer alpha granules, and smaller areas/perimeters than the infant platelets. Also, in infants greater than 31 weeks gestation, the platelets of vaginally-delivered infants were larger than those of both infants delivered by C-section and normal adults. These differences in platelet size and morphology may be related to developmental differences and/or the stress of delivery. These findings provide a framework for further exploration of neonatal platelet structure and function.

Adult↗
PubMed1993

Treatment of reflux esophagitis resistant to H2-receptor antagonists with lansoprazole, a new H+/K(+)-ATPase inhibitor: a controlled, double-blind study. Lansoprazole Study Group.

This multicenter, randomized, double-blind, 8-wk study compared the new H+/K(+)-ATPase inhibitor, lansoprazole, 30 mg daily, to ranitidine 150 mg bid for treatment of erosive reflux esophagitis resistant to histamine-2 receptor antagonists (H2RA). Patients were evaluated after 2, 4, 6, and 8 wk of treatment by symptom assessment and endoscopy. Healing rates for lansoprazole were 71%, 80%, 88%, and 89% at 2, 4, 6, and 8 wk, respectively, compared to 21%, 33%, 45%, and 38% for ranitidine (p < 0.001 at all points). Lansoprazole was significantly more effective than ranitidine for relief of heartburn and reduction of antacid tablet use. Increases in serum gastrin concentrations between the baseline and the 8-wk visit were greater in lansoprazole-treated than in ranitidine-treated patients. Lansoprazole was safe and well tolerated. In patients with erosive reflux esophagitis resistant to standard doses of H2RA, lansoprazole 30 mg/day is more effective than continuation of an H2RA (ranitidine 150 mg bid) for healing of esophagitis and improvement of symptoms.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1992

The effects of lansoprazole, a new H+,K(+)-ATPase inhibitor, on gastric pH and serum gastrin.

This study examined the effects of dose and time of administration of lansoprazole on gastric pH and serum gastrin in healthy male volunteers. Three groups of six subjects received 10, 20 or 60 mg doses of lansoprazole or placebo. Doses were administered at 22.00 hours daily for 7 days. An additional 18 subjects received once daily 30 mg oral doses of lansoprazole or placebo; these subjects were dosed at either 08.00 hours or 22.00 hours in a randomized, crossover fashion with a 2-week washout period. Gastric pH was monitored for 24 h following the first and final dose, and 1 week following the completion of dosing. Lansoprazole, at all doses except 20 mg/day, significantly increased the median 24-hour gastric pH following 7 days of dosing (P less than 0.05). In addition, morning dosing in the 30-mg crossover group led to a higher 24-h median pH than evening dosing (P = 0.003). There was no difference in night-time median pH between morning and evening dosing. Morning dosing also led to a significant increase in gastric pH on study Day 1 (P less than 0.05). Plasma concentrations of lansoprazole were highly variable between subjects, but there was a significant correlation between AUC and the median 24-h gastric pH. Plasma concentrations and AUCs were higher on Day 7 than on Day 1 for subjects receiving 10 or 20 mg, but not for those receiving 30 or 60 mg doses. Lansoprazole bioavailability demonstrated a circadian effect manifested by higher plasma concentrations following morning dosing. Serum gastrin concentrations were elevated in all active medication groups.

2-Pyridinylmethylsulfinylbenzimidazoles↗