Intragastric nitric oxide is abolished in intubated patients and restored by nitrite

OBJECTIVE: Nitrite in saliva is reduced to nitric oxide (NO) in the acidic stomach, and this NO may serve gastroprotective functions. We studied intragastric NO levels in healthy controls and in intubated intensive care unit patients before and after supplementation with nitrite. DESIGN: Prospective observational study involving patients and controls. SETTING: A mixed intensive care unit and a university laboratory. PATIENTS AND SUBJECTS: Eight healthy volunteers and ten intubated, mechanically ventilated intensive care unit patients. INTERVENTIONS: A tonometric catheter was first evaluated in vitro and then used for all NO measurements. In fasting controls, gastric NO levels were measured repeatedly during periods of saliva depletion and after an intragastric nitrite infusion. In patients, changes in levels of intragastric NO, nitrite in plasma and gastric juice, and S-nitrosothiols in gastric juice were measured in response to an intragastric nitrite infusion. MEASUREMENTS AND MAIN RESULTS: The tonometric catheter had a recovery of 80% with a high intraclass and interclass correlation. Median baseline NO levels in healthy volunteers were 21.6 ppm (interquartile range, 11.4-22.3 ppm) and decreased by 90% to 3.3 ppm (2.0-5.2 ppm) during 25-50 mins of saliva depletion. The NO level was restored by an intragastric nitrite infusion. Baseline NO levels in patients were almost abolished (0.1 ppm [0.07-0.4 ppm]) but increased rapidly to 124 ppm (range, 65-180 ppm) during intragastric nitrite infusion. Nitrite levels in plasma increased from 0.18 +/- 0.03 to 1.3 +/- 0.2 microM (p < .01), and levels of S-nitrosothiols in gastric juice increased from 0.12 +/- 0.09 to 6.7 +/- 1.8 microM. CONCLUSIONS: Intragastric generation of NO requires continuous delivery of nitrite-containing saliva and is almost abolished in critically ill, intubated patients. Enteral supplementation with nitrite could however fully restore gastric NO levels. Future studies will reveal if low NO levels contribute to stress ulcers and gastric overgrowth of bacteria often seen in these patients and in turn if restoring gastric NO with nitrite could be a useful therapeutic approach.     

Prevalence and Severity of Anal Incontinence in Women With and Without Additional Vaginal Deliveries After a Fourth-Degree Perineal Laceration

PURPOSE The aim of this study was to compare the prevalence and severity of anal incontinence among women who had undergone no, one, or at least two additional vaginal deliveries after sustaining a fourth-degree sphincter tear as a nullipara.METHODS We conducted a telephone survey to determine our subjects anal function. The incontinence score was determined by adding the content (flatus, liquid, and solid stool = 1, 2, and 3 points, respectively) and frequency (less than weekly, weekly, and daily = 1, 2, and 3 points, respectively) points. Severe incontinence is defined as having a score of 5 or 6 points and the incontinence having a severe effect on the subjects daily activities.RESULTS Of the 148 women interviewed, 52 had undergone zero (Group 1), 60 had had one (Group 2), and 36 had had at least two (Group 3) additional vaginal deliveries. Among the three groups, 20 of 52 (38 percent), 14 of 60 (23 percent), and 10 of 36 (28 percent), respectively, reported anal incontinence (P = 0.208). The proportion that had 1 or 2 points (8/20, 4/14, and 3/10, respectively, P = 0.75) and 3 or 4 points (10/20, 9/14, and 2/10, respectively, P = 0.097) was similar among the three groups. Two of 20 (10 percent), 1 of 14 (7 percent), and 5 of 10 (50 percent), respectively, had a score of 5 or 6 points (P = 0.012). For the three groups, 0 of 20, 0 of 14, and 4 of 10 (40 percent) reported that their incontinence had a severe effect on their daily activities (P = <0.001), and 0 of 52, 0 of 60, and 4 of 36 (11 percent) had severe incontinence (P = 0.002).CONCLUSIONS The proportion that had severe incontinence was significantly higher among women who had undergone at least two additional deliveries.Supported by a grant from East Carolina University Brody School of Medicine Faculty Research Fund.Presented at the scientific meeting of the American Urogynecologic Society, San Francisco, California, October 17 to 19, 2002.Reprints are not available.     

Contributions of lower limb and abdominal compression to ventilation inhomogeneity in hypergravity

Gravito-inertial load in the head-to-foot direction (Gz) and compression of the lower body half by an anti-G suit (AGS) are both known to influence ventilation distribution in the lungs. To study the interaction of Gz and AGS and to asses the separate contributions from lower limbs and abdominal compressions to large and small-scale ventilation inhomogeneities nine males performed SF6/He vital capacity (VC) single-breath washouts at 1, 2, and 3 Gz in a centrifuge, with abdominal and/or lower limbs compressions. SF6/He and (SF6-He) phase III slopes were used for determination of overall and small-scale ventilation inhomogeneity. Closing volume and phase IV height were used as measures of large-scale inhomogeneity. VC decreased marginally with G-load but markedly with lower limbs compression. Small-scale ventilation inhomogeneity increased slightly with G-load, but substantially with AGS pressurization. Small-scale ventilation inhomogeneity increased with AGS pressurization. Large-scale inhomogeneity increased markedly with G-load. Translocation of blood to the lungs might be the key determinant for changes in small-scale ventilation inhomogeneity when pressurizing an AGS.     

Topiramate-valproate-induced hyperammonemic encephalopathy syndrome: case report

A 15-year-old boy with inverted duplication of chromosome 15 was admitted for acute onset of irritability, increasing sleepiness, and worsening of seizures. He had been on valproate and other anti-convulsants. However, he was found to have hyperammonemia within 2 weeks after the addition of low-dose topiramate to valproate. He recovered within 7 days after discontinuation of valproate. Topiramate was tailed off. The reintroduction of valproate monotherapy caused hyperammonemia again without clinical features of encephalopathy. He also developed anticonvulsant hypersensitivity syndrome following the use of phenytoin. We propose the term topiramate-valproate-induced hyperammonemic encephalopathy syndrome to include the following features: excessive sleepiness or somnolence, aggravation of seizures, hyperammonemia, and absence of triphasic waves on electroencephalography in any individual on simultaneous topiramate-valproate therapy. The ammonia level ranged from 1.5 to 2 times normal. The serum valproate level might be within the therapeutic range. The possible mechanism is topiramate-induced aggravation of all the known complications of valproate monotherapy. This condition is reversible with cessation of either valproate or topiramate.     

G tolerance and pulmonary effects of removing chest counterpressure during pressure breathing

BACKGROUND: In agile fighter aircraft positive pressure breathing is commonly used as part of the anti-G ensemble. To optimize G protection and prevent over-distention of the lungs, increased airway pressure is balanced by applying a counterpressure to the chest. The aim was to investigate the efficacy of chest counterpressure. METHODS: Three series of experiments were performed using the anti-G ensemble of the 39 Gripen aircraft (AGE-39) and exposing the subjects to 20-s G time profiles; in the first (n = 12) up to +8.0 Gz, in the second (n = 9) up to + 9.0 Gz, and also to simulated aerial combat maneuvers (SACM). Central and peripheral vision, arterial and airway pressures, pressure in the lower portion of the esophagus, and chest wall distension were measured. In the third series, six subjects were exposed to up to +7.0 Gz and esophageal pressure was measured in the upper thorax. In all series, two conditions were compared: with and without pressurized chest bladder. RESULTS: During the 20-s profiles arterial and esophageal pressures, chest wall distension, and visual impairment were similar with and without pressurized chest bladder. Upper esophageal pressure was slightly higher by 10-24% with than without chest bladder (p = 0.03). During SACM, time to exhaustion and the level of perceived exertion were similar with and without pressurized chest bladder. SUMMARY: The results suggest that the chest counterpressure can be removed from the AGE-39 without diminishing G tolerance or G endurance or significantly increasing the risk of lung parenchyma disruption.     

Insecticide resistance in Alabama and Florida mosquito strains of Aedes albopictus

The susceptibility of four strains of Aedes albopictus (Skuse) to permethrin, deltamethrin, resmethrin, chlorpyrifos, malathion, propoxur, fipronil, imidacloprid, spinosad, and Bacillus thuringiensis variety israelensis (Bti) was determined. The HAmAal and MAmAal strains were collected in 2002 and 2003, respectively, from Huntsville and Mobile, AL, and the VBFmAal and SFmAal strains were collected in 1998 from Vero Beach and southern Florida, respectively. The HAmAal strain showed a 22-fold elevated level of resistance to deltamethrin compared with the susceptible Ikaken laboratory strain, whereas the VBFmAal strain showed a six-fold lower sensitivity to deltamethrin compared with Ikaken. However, comparison of resistance ratios for deltamethrin at LC50 and LC90 (21-fold) and the gradual slopes of dose-response curves indicated that the field population of this mosquito strain was heterogenous in response to deltamethrin. All four mosquito strains showed elevated levels of resistance to chlorpyrifos, with resistance ratios from 10 to 33. Nevertheless, except for the relatively low resistance to deltamethrin and chlorpyrifos, all mosquito strains showed a similar susceptibility or lower tolerance to the remaining insecticides tested compared with the susceptible Ikaken strain, even though some, such as permethrin, resmethrin, malathion, and Bti, have been used in the field for a long time, especially in Alabama. These results indicate that the development of resistance to insecticides in Ae. albopictus is slow and conventional insecticides, such as permethrin, resmethrin, malathion, and Bti, and relatively new insecticides, such as fipronil, imidacloprid, and spinosad, may all be valuable for the management of this important mosquito.     

Increased frequency of bacterial vaginosis and Chlamydia trachomatis in pregnant women with human papillomavirus infection

The aim of this study was to verify the presence of bacterial vaginosis (BV), Candida sp, Chlamydia trachomatis, Neisseria gonorrhoeae, to determine the prevalence of tobacco use and measure vaginal pH (VpH) in pregnant women with (n = 26) and without (n = 26) human papillomavirus (HPV) infection, and make comparisons between these 2 groups. HPV, C. trachomatis and N. gonorrhoeae were diagnosed using hybrid capture, BV using clinical criteria, and Candida sp via cultures. A digital pH meter was used to measure VpH. The frequencies of Candida sp were 19.2 and 23.1% (p = 1), and VpH was 4.4 +/- 0.4 and 4.3 +/- 0.4 (p = 0.23), in the HPV-positive and HPV-negative groups, respectively. Compared to the group of pregnant women without HPV infection, those with HPV infection had a significantly higher prevalence of tobacco use (50 vs. 11.5%; p = 0.006), BV (53.8 vs. 15.4%; p = 0.007), and C. trachomatis (34.6 vs. 7.7%; p = 0.039). No case of N. gonorrhoeae was diagnosed. All cases of C. trachomatis and BV had high-grade HPV infection.