Vibrant Soundbridge® in preschool children with unilateral aural atresia: acceptance and benefit.

The aim of this pilot study was to determine the acceptance and benefit from the middle ear implant system Vibrant Soundbridge® (VSB, MED-EL Corporation, Austria) by means of a questionnaire, compared to a previously used conventional bone conducting hearing device, in preschool children with unilateral congenital aural atresia. Prospective cohort study. All nine children with unilateral congenital aural atresia used the VSB and had previous experience with a bone conducting hearing device. The benefit from the VSB was evaluated by questionnaires concerning acceptance of hearing aids, handling, listening effort, behavior, quality of life, and the duration of daily use and compared to the experience with the bone conducting hearing device. In addition, to quantify the benefit from the VSB use, audiological assessment (pure-tone audiometry via free field testing, speech audiometry, and localization test) was performed with and without VSB. The questionnaires and audiological test results were compared pairwise. According to all questionnaire areas, children benefited significantly more from the VSB compared to bone conducting hearing device (ps <.05). The most important finding was a significant increase in daily use from 2 h for the bone conducting hearing device to 10 h for the VSB. Children performed significantly better with the VSB than without it in the audiological assessment. Children with unilateral aural atresia benefited significantly more from the VSB compared to a conventional bone conducting hearing device according to the parents' questionnaires and yielded better results in the audiometry and localization test with the VSB than without it.

[Vibrant Soundbridge®: An Alternative Hearing System for Preschool Children with Aural Atresia]. / Die Vibrant Soundbridge®: Ein alternatives Hörsystem bei Vorschulkindern mit Gehörgangsatresie.

BACKGROUND: The audiological treatment of children with aural atresia makes high demands on physicians and acousticians. Conventional hearing systems are often not tolerated by children and therefore do not meet the needs of the early and efficient therapy of hearing disorders. Aim of the present study was the evaluation of the audiological functional gain in children with uni- and bilateral aural atresia provided with the middle ear implant Vibrant Soundbridge(®) (VSB(®)) below the age of 6 years as well as the analysis of parents' satisfaction assessed with questionnaires. MATERIAL AND METHODS: The VSB(®) was implanted in 16 children, 13 with unilateral and 3 with bilateral aural atresia, with the mean age of 2;11±1;6 years. 3 months after the first fitting of the audio processor, pure-tone audiometry via free field testing with and without the hearing system was performed. Furthermore, parents completed a standardized questionnaire to evaluate their satisfaction with the VSB(®) treatment quality. The questionnaire included items on the acceptance by children, handling, listening effort, behavior, satisfaction, quality of life, aesthetics, and the length of daily use. RESULTS: The use of the VSB(®) resulted in a significantly improved hearing level: 20 dB on average (Z=- 3.06; p=0.002; n=12). The analysis of parents' questionnaire demonstrated high or very high satisfaction with VSB(®) in all subjects. Primarily, the length of daily use of the VSB(®) was significantly higher than that of the hearing system used before with 10.0±2.1 vs. 2.7±2.2 h per day (Z=- 3.06; p=0.002; n=14). CONCLUSION: The VSB(®) presented a good alternative for audiological treatment of uni- and bilateral aural atresia at toddler and pre-school age.

[Validation of the German short version of the Murray Secretion Rating Scale]. / Validierung der deutschen Kurzversion der Sekretbeurteilungsskala nach Murray.

OBJECTIVE: Accumulation of secretions in hypopharynx, aditus vestibule, and trachea is often found in cases of severe dysphagia and is considered a cardinal trait of high clinical and therapeutic importance. For the graduation of the severity level of accumulated secretions, a short version of the 4-point Murray secretion scale is available, which is also integrated into the protocol of the fiberoptic endoscopic evaluation of swallowing (FEES) according to the Langmore standard. This study aimed at the validation of the German translation of this short version in order to facilitate a uniform, standardized evaluation of the accumulation of secretions in dysphagic patients in the German language area. MATERIAL AND METHODS: For the examination of reliability and validity, a reference standard was defined by 2 dysphagia experts on the basis of 40 video files of the FEES examination, 10 videos for each of the severity grades. Afterwards, these videos were rated independently by 4 raters and re-rated in a new randomized order 2 weeks later. RESULTS: Both the intra-rater reliability (τ>0,830***) and the inter-rater reliability (Kendalls W>0,890***) were highly significant and can be considered good. The same is valid for the correlation of ratings with the reference standard (τ=0,969***). CONCLUSIONS: The German translation of the short version of the 4-point Murray secretion scale is recommendable as a reliable and valid instrument for the graduation of the cardinal trait of oropharyngeal dysphagia and also as an evidence-based instrument for standardized use in the German language area.

[Quality Assurance in the Endoscopic Evaluation of Swallowing (FEES)]. / Qualitätssicherung der endoskopischen Schluckdiagnostik (FEES).

BACKGROUND: A fiberoptic endoscopic evaluation of swallowing (FEES) is well established internationally as gold standard of the instrument-based diagnostics if it is performed according to the Langmore-protocol. For the quality assurance of FEES, videotaping is recommended. However, often no videotaping is carried out due to a limited availability of portable recording systems, for instance, in the bedside diagnostics. This study aimed at the comparison of FEES quality assurance with and without videotaping by rating of the main finding in swallowing disorders, the penetration and aspiration, as defined in the penetration-aspiration scale by Rosenbek. MATERIAL AND METHODS: An examination of agreement of penetration and aspiration ratings with the defined reference standard was conducted by means of 80 videotaped recordings. The ratings were carried out independently by 4 raters in 2 settings: A) "real time" and B) "frame-by-frame". RESULTS: As far as the interrater- and intrarater-reliability is concerned, the association between the ratings in the rating setting B were higher than those in the rating setting A. Furthermore, examination of the validity showed higher correlation in setting B than in setting A. The difference between correlations was significant in favor of setting B (videotaped FEES). CONCLUSION: The results of the present study, namely better rating reliability and validity in case of the penetration and aspiration, emphasize the importance of the videotaping of the FEES diagnostics, at least for the evaluation of penetration or aspiration.

[Secretion scale by Murray et al. for FEES®: comparison of reliability and validity of the German long and short version]. / Sekretbeurteilungsskala nach Murray et al. für FEES(®) : Reliabilitäts- und Validitätsvergleich der deutschen Lang- und Kurzversion.

BACKGROUND: Accumulation of secretions in the hypopharynx, aditus laryngis and trachea constitute a cardinal trait of oropharyngeal dysphagia. For the evaluation of the degree of severity a 4-point secretion scale by Murray et al. is used internationally in a long and a short version. However, a validated German translation of the long version of this scale does not yet exist. Also, it has not yet been scientifically proven that both versions of the scale are equally valid. OBJECTIVES: This study aimed at the validation of the German translation of the long version of the secretion scale by Murray et al. and at a comparison of reliability and validity of the short and long versions. MATERIAL AND METHODS: A total of 40 videos of fiberoptic endoscopic evaluation of swallowing (FEES(®)), 10 for each severity level, were rated by 4 otorhinolaryngologists (ENT specialists) independently and with different randomizations for examination of the reliability and validity. Two rating sessions for each of the scale versions were conducted. Intrarater and interrater reliability as well as the agreement of the ratings with a reference standard were analyzed. RESULTS: Both the intrarater reliability (Spearman correlations: ρs > 0.840***) and the interrater reliability (Krippendorff's alpha: α > 0.850) yielded very good results and the concurrent validity was highly significant (ρs > 0.981***). DISCUSSION: The German translation of the secretion scale by Murray et al. can be considered reliable and valid, with comparable test accuracy of the short and long versions. Hence, the scale can be recommend for the graduation of pharyngolaryngotracheal secretions and should be integrated into the standardized evaluation of FEES(®) diagnostics for clinical and scientific purposes.

[Penetration-Aspiration Scale according to Rosenbek. Validation of the German version for endoscopic dysphagia diagnostics]. / Penetrations-Aspirations-Skala nach Rosenbek. Validierung der deutschen Version für die endoskopische Dysphagiediagnostik.

BACKGROUND: The Penetration-Aspiration Scale was developed by Rosenbek et al. to enable standardized documentation of this cardinal symptom of a swallowing disorder. OBJECTIVES: The objective was to create and validate a German version of the Penetration-Aspiration Scale according to the guidelines governing the translation of foreign language measurement tools. MATERIALS AND METHODS: Both reliability and validity were examined based on the ratings of 80 randomized endoscopically evaluated swallows, 10 for each severity level. Ratings were carried out by four independent raters: two with more than 3 years' experience with dysphagia and a further two with less than 3 years' experience. The swallows were rerated after 4 weeks. RESULTS: Both intrarater (Kendall's Tau: τs > 0.643; median 0.773; ps < 0.001) and interrater reliability were highly significant (two-way mixed single ICC coefficient of 0.799 for the first rating session and 0.728 for the second session; ps < 0.001). Results from the raters with less than 3 years' experience were significantly different from the reference standard in three out of four cases, whereas this was not the case for the more experienced raters. However, for each film, the median of the individual ratings from all four raters correlated almost perfectly with the reference standard (first rating session: τ = 0.894; second rating session: τ = 0.843; ps < 0.001). CONCLUSION: The German version of the Penetration-Aspiration Scale according to Rosenbek presented here was demonstrated to be both reliable and valid. Despite its dependency on the raters' experience, it can therefore be used as a graduation instrument for swallowing disorders in German-speaking countries and make an important contribution to evidence-based medicine in dysphagiology for both clinical and scientific use.

High prevalence of hearing loss at the special olympics: is this representative of people with intellectual disability?

BACKGROUND: The Healthy Hearing (HH) programme at the Special Olympics (SO) revealed hearing disorders in between 16 and 40% of athletes. However, it is not clear whether these prevalence represents the entire population with intellectual disability. Therefore, this study compares the hearing status of SO athletes with an intellectual disability (ID) to students with ID at a special needs school. MATERIALS AND METHODS: The HH screening was performed in 637 athletes (mean age 27.1 years, range 9.7-70.6 years) during the 2008 German SO Summer Games - and in 198 special needs students (mean age 12.7 years, range 6.7-20.0 years). RESULTS: Twenty-two per cent of athletes and 18% of students failed the HH screening. Approximately 60% of the total participants received recommendations for further follow-up and treatment without between-group differences. CONCLUSIONS: The results of the HH screening at SO events are assumed to be representative of children and adolescents with ID in special needs schools.

[Improved efficiency in swallowing diagnostics using an electronic documentation system]. / Effektivierung der Schluckdiagnostik durch ein elektronisches Dokumentationssystem.

BACKGROUND: The aim is to present a German-language electronic documentation system for the fiberoptic endoscopic evaluation of swallowing (FEES) in order to make routine swallowing diagnostics and therapeutic recommendations more effective and as initial confirmation of its suitability for daily use. METHODS: Time-efficient, precise, and complete documentation is provided by an interactive findings system via preset text fields and integration of representative frames with automatic report generation. This documentation system (FEED) (Flexible Endoscopic Evaluation of Dysphagia, XION medical GmbH, Berlin) was applied to 301 digitized FEES recordings. RESULTS: Of the parameters required by the FEES protocol, 97% were recorded in 9 min on average. Altogether, the application of FEED resulted in a time-saving of more than 50% as compared to free protocols. The use of the Murray and Rosenbek scales enabled a graded evaluation of swallowing disorders. CONCLUSIONS: FEED shortens documentation time, improves report quality and has proven to be a practical instrument in making routine swallowing diagnostics and therapy more effective.

High prevalence of hearing disorders at the Special Olympics indicate need to screen persons with intellectual disability.

BACKGROUND: Persons with intellectual disabilities (ID) are at increased risk for hearing impairment which often remains undetected. If left untreated, such hearing impairments may worsen the social and communicative problems of these persons. The aims of this study are to determine the prevalence of hearing impairment, to specify type and degree of hearing loss, and to evaluate the sensitivity and specificity of the screening in this population. METHODS: During the German Special Olympics Summer Games 2006, 552 athletes with ID had their hearing screened according to the international protocol of Healthy Hearing, Special Olympics. This screening protocol includes otoscopy, measurement of distortion product otoacoustic emissions, and - if necessary - tympanometry and pure tone audiometry (PTA) screening at 2 and 4 kHz. Additionally, 195 athletes underwent a full diagnostic PTA. The results of the screening and diagnostic PTA were compared. RESULTS: Of the 524 athletes who completed the screening protocol, 76% passed and 24% failed it. Ear wax was removed in 48% of all athletes. 42% of the athletes were recommended to consult an otolaryngologist or an acoustician. Of the 99 athletes whose screening-based suspicion of a hearing loss was confirmed with diagnostic PTA, 74 had an undetected hearing loss. The correlation (Cramer's V) between screening and diagnostic PTA was .98. The sensitivity of the screening was 100% and the specificity 98%. DISCUSSION: The screening reliably detects hearing disorders among persons with ID. The prevalence of hearing impairment in this population is considerably higher than in the general population, and the proportion of undetected hearing impairments is large, even among people with only mild and moderate ID, as examined in this study. Therefore, a screening is highly recommended, and special attention from caregivers and professionals as well as regular hearing assessment and standard therapy programmes are required for persons with ID.

Phosphodiesterase inhibitors and forskolin Up-regulate arginase activity in rabbit alveolar macrophages.

Alveolar macrophages (AMsmall ef, Cyrillic) express considerable arginase activity which can be modulated by various mediators. As inhibitors of phosphodiesterase (PDE) play an increasing role in the treatment of chronic inflammatory and obstructive airway disease, we tested whether PDE inhibitors affect arginase activity in AMsmall ef, Cyrillic. Isolated rabbit AMsmall ef, Cyrillic were cultured for 20 h in the absence or presence of bacterial lipopolysaccharides (LPS) and/or different test substances. Thereafter arginase activity was determined by measuring the formation of [(3)H]-L-ornithine during 1 h incubation with [(3)H]-L-arginine. Lipopolysaccharide-enhanced (0. 01-5 microg/ml) maximal arginase activity by about 2.5-fold. The non-selective PDE inhibitor IBMX and the PDE4 selective inhibitor rolipram (each up to 30 microM) caused a 2.4-fold increase in arginase activity, and these effects were additive to those of LPS. The PDE3-selective inhibitor siguazodan had only marginal effects. Forskolin (10 microM) also enhanced arginase activity in the absence and presence of LPS. The effect of forskolin was almost prevented by cycloheximide (30 microM) and largely attenuated by the protein kinase A inhibitor KT 5720 (300 nM). In conclusion, inhibition of the cAMP-specific PDE4, like direct activation of adenylyl cyclase, causes an up-regulation of arginase activity in rabbit AMsmall ef, Cyrillic.

Cationic proteins inhibit L-arginine uptake in rat alveolar macrophages and tracheal epithelial cells. Implications for nitric oxide synthesis.

Eosinophil-derived cationic proteins play an essential role in the pathogenesis of bronchial asthma. We tested whether cationic proteins interfere with the cationic amino-acid transport in alveolar macrophages (AMPhi) and tracheal epithelial cells, and whether L-arginine-dependent pathways were affected. The effect of cationic polypeptides on cellular uptake of [(3)H]-L-arginine, nitrite accumulation, and the turnover of [(3)H]-L-arginine by nitric oxide (NO) synthase and arginase (formation of [(3)H]-L-citrulline and [(3)H]-L-ornithine, respectively) were studied. Poly-L-arginine reduced [(3)H]-L-arginine uptake in rat AMPhi and tracheal epithelial cells in a concentration-dependent manner (at 300 microgram/ml by 70%). Poly-L-lysine, protamine, and major basic protein (each up to 300 microgram/ml) tested in rat AMPhi inhibited [(3)H]-L-arginine uptake by 35 to 50%. During 6 h incubation in amino acid-free Krebs solution, rat AMPhi, precultured in the absence or presence of LPS (1 microgram/ml), accumulated 1.4 and 3.5 nmol/10(6) cells nitrite, respectively. Addition of 100 microM L-arginine increased nitrite accumulation by 70 and 400% in control and lipopolysaccharide-treated AMPhi, respectively. Nitrite accumulation in the presence of L-arginine was reduced by poly-L-arginine and poly-L-lysine (100 and 300 microgram/ml) by 60 to 85% and 20 to 30%, respectively. Poly-L-arginine, but not poly-L-lysine, inhibited nitrite accumulation already in the absence of extracellular L-arginine. Poly-L-arginine (300 microgram/ml) inhibited [(3)H]-L-citrulline formation by AMPhi stronger than that of [(3)H]-L-ornithine. We conclude that cationic proteins can inhibit cellular transport of L-arginine and this can limit NO synthesis. Poly-L-arginine inhibits L-arginine uptake more effectively than other cationic proteins and exerts additional direct inhibitory effects on NO synthesis.

Open versus laparoscopic adjustable silicone gastric banding: a prospective randomized trial for treatment of morbid obesity.

OBJECTIVE: To perform the first prospective trial of laparoscopic versus open adjustable silicone gastric banding (ASGB) in patients with morbid obesity. SUMMARY BACKGROUND DATA: Vertical banded gastroplasty has been used for many years to treat morbid obesity, but the size of the stoma has remained a source of failure after the procedure. ASGB has the advantages of maintaining gastric integrity and the potential for readjustment of the band, if needed. It has been suggested that laparoscopic ASGB, recently introduced to reduce postoperative complications and hospital stay, has a negative impact on outcome. METHODS: Fifty patients with morbid obesity of >5 years' duration and a body-mass index (BMI) > 40 kg/m2 were randomized to undergo laparoscopic or open ASGB. The difficulty of the procedure, surgical time, postoperative complications, and hospital stay were assessed. Stoma adjustments, long-term complications, readmissions, weight loss, and BMI were determined. RESULTS: All procedures were successfully carried out. Of 25 patients assigned to laparoscopic ASGB, 2 were converted to an open procedure. Surgical time was significantly longer for laparoscopic ASGB (150 minutes vs. 76 minutes for open ASGB). There was no difference in complications. Mean hospital stay was 5.9 days for the laparoscopic procedure versus 7.2 days for open ASGB (p < 0.05). The total number of readmissions (6 vs. 15) and overall hospital stay in the first year (7.8 vs. 11.8 days) were lower after laparoscopic ASGB (p < 0.05). Weight and BMI were reduced significantly in both groups, but there was no difference between the groups. CONCLUSION: Laparoscopic and open ASGB were equally effective in terms of early (first-year) weight loss, reduction of BMI, and postoperative complications. The laparoscopic procedure was associated with a shorter initial hospital stay and fewer readmissions during follow-up and is therefore the preferred treatment in morbidly obese patients undergoing ASGB.

Activation of L-arginine transport by protein kinase C in rabbit, rat and mouse alveolar macrophages.

1. The role of protein kinase C in controlling L-arginine transport in alveolar macrophages was investigated. 2. L-[3H]Arginine uptake in rabbit alveolar macrophages declined by 80 % after 20 h in culture. 4beta-Phorbol 12-myristate 13-acetate (PMA), but not 4alpha-phorbol 12-myristate 13-acetate (alpha-PMA), present during 20 h culture, enhanced L-[3H]arginine uptake more than 10-fold. Staurosporine and chelerythrine opposed this effect. 3. L-[3H]Arginine uptake was saturable and blockable by L-lysine. After PMA treatment Vmax was increased more than 5-fold and Km was reduced from 0.65 to 0.32 mM. 4. Time course experiments showed that PMA increased L-[3H]arginine uptake almost maximally within 2 h. This short-term effect was not affected by cycloheximide or actinomycin D. 5. L-[3H]Arginine uptake and its stimulation by PMA was also observed in sodium-free medium. 6. L-Leucine (0.1 mM) inhibited L-[3H]arginine uptake by 50 % in sodium-containing medium, but not in sodium-free medium. At 1 mM, L-leucine caused significant inhibition in sodium-free medium also. L-Leucine showed similar effects on PMA-treated cells. 7. N-Ethylmaleimide (200 microM, 10 min) reduced L-[3H]arginine uptake by 70 % in control cells, but had no effect on PMA-treated (20 or 2 h) cells. 8. In alveolar macrophages, multiple transport systems are involved in L-arginine uptake, which is markedly stimulated by protein kinase C, probably by modulation of the activity of already expressed cationic amino acid transporters.

Inhibition of arginase in rat and rabbit alveolar macrophages by N omega-hydroxy-D,L-indospicine, effects on L-arginine utilization by nitric oxide synthase.

1. Alveolar macrophages (AM phi) exhibit arginase activity and may, in addition, express an inducible form of nitric oxide (NO) synthase (iNOS). Both pathways may compete for the substrate. L-arginine. The present study tested whether two recently described potent inhibitors of liver arginase (N omega-hydroxy-D,L-indospicine and 4-hydroxyamidino-D,L-phenylalanine) might also inhibit arginase in AM phi and whether inhibition of arginase might affect L-arginine utilization by iNOS. 2. AM phi obtained by broncho-alveolar lavage of rat and rabbit isolated lungs were disseminated (2.5 or 3 x 10(6) cells per well) and allowed to adhere for 2 h. Thereafter, they were either used to study [3H]-L-arginine uptake (37 kBq, 0.1 microM, 2 min) or cultured for 20 h in the absence or presence of bacterial lipopolysaccharide (LPS). Cultured AM phi were incubated for 1 h with [3H]-L-arginine (37 kBq, 0.1 microM) and the accumulation of [3H]-L-citrulline (NOS activity) and [3H]-L-ornithine (arginase activity) was determined. 3. During 1 h incubation of rabbit AM phi with [3H]-L-arginine, no [3H]-L-citrulline, but significant amounts of [3H]-L-ornithine (150 d.p.m x 1000) were formed. N omega-hydroxy-D,L-indospicine and 4-hydroxyamidino-D,L-phenylalanine, present during incubation, concentration-dependently reduced [3H]-L-ornithine formation (IC50: 2 and 45 microM, respectively). 4. N omega-hydroxy-D,L-indospicine (up to 100 microM) had no effect on [3H]-L-arginine uptake into rabbit AM phi, whereas 4-hydroxyamidino-D,L-phenylalanine caused a concentration-dependent inhibition (IC50: 300 microM). 5. Rat AM phi, cultured in the absence of LPS, formed significant amounts of [3H]-L-citrulline and [3H]-L-ornithine (133 and 212 d.p.m x 1000, respectively) when incubated for 1 h with [3H]-L-arginine. When AM phi had been cultured in the presence of 0.1 or 1 microgram ml-1 LPS, the formation of [3H]-L-citrulline was enhanced by 37 +/- 8.3 and 99 +/- 12% and that of [3H]-L-ornithine reduced by 21 +/- 8.7 and 70 +/- 2.5%, respectively. 6. In rat AM phi, cultured in the absence or presence of LPS, N omega-hydroxy-D,L-indospicine (10 and 30 microM) greatly reduced formation of [3H]-L-ornithine (by 80-95%) and this was accompanied by increased formation of [3H]-L-citrulline. However, only 20-30% of the [3H]-L-arginine not metabolized to [3H]-L-ornithine after inhibition of arginase was metabolized to [3H]-L-citrulline, when the AM phi had been cultured in the absence of LPS (i.e. low level of iNOS). On the other hand, when the AM phi had been cultured in the presence of LPS (i.e. high level of iNOS), all the [3H]-L-arginine not metabolized by the inhibited arginase was metabolized to [3H]-L-citrulline. 7. In conclusion, N omega-hydroxy-D,L-indospicine is a potent and specific inhibitor of arginase in AM phi. In cells in which, in addition to arginase, iNOS is expressed, inhibition of arginase can cause a shift of L-arginine metabolism to the NOS pathway. However, the extent of this shift appears to depend in a complex manner on the level of iNOS.

Endogenous nitric oxide inhibits leukotriene B4 release from rat alveolar macrophages.

Effects of endogenous nitric oxide (NO) on the release of mediators of the lipoxygenase and cyclo-oxygenase pathway from rat alveolar macrophages were studied. Alveolar macrophages, freshly isolated or after 18-h culture, were incubated in (amino acid-free) Krebs medium and labelled with [3H]arachidonic acid. The release of [3H]leukotriene B4 and [3H]prostanoids (separated by high performance liquid chromatography) was determined. A 23187 was used as stimulus, as rising intracellular Ca2+ activates directly the phospholipase A2 and lipoxygenase pathway. A 23187 (10 microM) enhanced [3H]leukotriene B4 release from freshly prepared alveolar macrophages about 65-fold, but only 5- to 6-fold from cultured alveolar macrophages. Evoked [3H]leukotriene B4 release and spontaneous [3H]prostanoid release were inhibited when L-arginine (300 microM) was added to the Krebs incubation medium of alveolar macrophages, in which marked NO synthase had been induced by culture with lipopolysaccharides (10 microg/ml). Inhibitory effects of L-arginine were prevented by N(G)-monomethyl-L-arginine (L-NMMA, 100 microM). Inhibition of NO synthase during the culture period by L-NMMA (culture medium, in contrast to Krebs medium, already contains the substrate of NO synthase, L-arginine), resulted in attenuation of the 'culture-dependent' decline of the evoked release of [3H]leukotriene B4 and allowed lipopolysaccharides to cause an increase in spontaneous [3H]prostanoid release (i.e., to induce cyclo-oxygenase activity). In conclusion, in rat alveolar macrophages, endogenous NO appears to inhibit the release of mediators of the cyclo-oxygenase and lipoxygenase pathway through multiple sites of action.

Stimulation-induced 3H-L-citrulline accumulation in isolated longitudinal muscle myenteric plexus preparations of rat small intestine: a measure to characterize nitrergic neurons.

Nitric oxide (NO) synthase activity in rat isolated longitudinal muscle myenteric plexus preparations of the small intestine was determine by measuring the accumulation of 3H-L-citrulline during 30 min incubation with 3H-L-arginine. In untreated preparations a significant amount of 3H-L-citrulline accumulated in the tissue, about 2000 dpm/30 mg per 30 min, accounting for about 1.7% of the tissue radioactivity. Intermittent electrical field stimulation (15 Hz, 10 s trains with 10 s intervals for total of 20 min) caused a threefold increase in 3H-L-citrulline accumulation. The NO synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME) reduced the spontaneous accumulation of 3H-L-citrulline by 65% and prevented the electrically evoked increase. Removal of extracellular calcium or addition of tetrodotoxin blocked the electrically evoked increase in 3H-L-citrulline accumulation without affecting spontaneous accumulation. Application of the calcium ionophore A 23187 (10 mumol/l) or 45 mmol/l) or 45 mmol/l potassium caused a twofold increase in the accumulation of 3H-L-citrulline. The muscarine receptor agonist oxotremorine (1 mumol/l) had no effect on spontaneous accumulation of 3H-L-citrulline, but inhibited the electrically evoked increase by about 50%, and this effect was blocked by scopolamine. A substantial amount of 3H-L-citrulline (15000 dpm) accumulated also in the incubation media, and this was increased 1.7-fold by the presence of A 23187 and 2.7-fold by electrical stimulation. However, electrically evoked increase in 3H-L-citrulline was not prevented by tetrodotoxin, in contrast to observation on tissue levels. In conclusion, during incubation with 3H-L-arginine tissue levels of 3H-L-citrulline in rat isolated longitudinal muscle myenteric plexus preparations, but not accumulation in incubation media may be used as a biochemical marker of the activity of nitrergic intestinal neurons which appear to be inhibited via muscarine receptors.

Nitric oxide synthase activity is inducible in rat, but not rabbit alveolar macrophages, with a concomitant reduction in arginase activity.

Alveolar macrophages were obtained by broncho-alveolar lavage of isolated rat and rabbit lungs and cultured (2.5 x 10(6) cells/dish) for 18 h in the absence or presence of bacterial lipopolysaccharides (LPS) alone or in combination with cytokines. Thereafter, accumulation of 3H-citrulline (NO synthase activity) and 3H-ornithine (arginase activity) were determined. During incubation of rat alveolar macrophages with 3H-arginine clear amounts of 3H-citrulline and 3H-ornithine (3.8 and 4.6% of the added 3H-arginine, respectively) were formed and most of these metabolites appeared in the incubation medium (ratios extra-/intracellular of 17 and 70 for 3H-citrulline and 3H-ornithine, respectively). When rat alveolar macrophages had been cultured with LPS the formation of 3H-citrulline was increased about 30-fold and this was accompanied by a reduction in 3H-ornithine formation of about 60%. The effects of LPS were largely attenuated by dexamethasone (10 mumol/l). Inhibition of NO synthase by NG-monomethyl-L-arginine (L-NMMA, 100 mumol/l) in LPS treated alveolar macrophages reduced the formation 3H-citrulline by more than 90% and restored the 3H-ornithine formation. After culturing in the presence of LPS the ratios extra/intracellular of 3H-citrulline and 3H-ornithine were markedly enhanced and this effect was not dexamethasone sensitive.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of arginase by NG-hydroxy-L-arginine in alveolar macrophages: implications for the utilization of L-arginine for nitric oxide synthesis.

The hypothesis was investigated that the nitric oxide (NO) synthase intermediate, NG-hydroxy-L-arginine (HOArg), is an arginase inhibitor in rabbit or rat alveolar macrophages. Exogenously applied HOArg strongly inhibited the arginase activity present in these cells (IC50 > or = 15 microM), and attenuated L-[3H]arginine transport (IC50 > or = 500 microM) in rabbit alveolar macrophages. Moreover, up to 37 microM HOArg were detected in the conditioned medium, but not in the lysate, of rat alveolar macrophages exposed to bacterial lipopolysaccharide for 18 h. HOArg may thus be a potent endogenous arginase inhibitor in these cells which increases the availability of L-arginine for NO biosynthesis.