Triamcinolone and prednisolone affect contractile properties and histopathology of rat diaphragm differently.

Diaphragm atrophy and weakness occur after administration of massive doses of corticosteroids for short periods. In the present study the effects of prolonged administration of moderate doses of fluorinated and nonfluorinated steroids were investigated on contractile properties and histopathology of rat diaphragm. 60 rats received saline, 1.0 mg/kg triamcinolone, or 1.25 or 5 mg/kg i.m. prednisolone daily for 4 wk. Respiratory and peripheral muscle mass increased similarly in control and both prednisolone groups, whereas triamcinolone caused severe muscle wasting. Maximal tetanic tension averaged 2.23 +/- 0.54 kg/cm2 (SD) in the control group. An increased number of diaphragmatic bundles in the 5-mg/kg prednisolone group generated maximal tetanic tensions < 2.0 kg/cm2 (P < 0.05). In addition, fatigability during the force-frequency protocol was most pronounced in this group (P < 0.05). In contrast, triamcinolone caused a prolonged half-relaxation time and a leftward shift of the force-frequency curve (P < 0.05). Histological examination of the diaphragm showed a normal pattern in the control and 1.25-mg/kg prednisolone group. Myogenic changes, however, were found in the 5-mg/kg prednisolone group and, more pronounced, in the triamcinolone group. Selective type IIb fiber atrophy was found in the latter group, but not in the prednisolone groups. In conclusion, triamcinolone induced type IIb fiber atrophy, resulting in reduced respiratory muscle strength and a leftward shift of the force-frequency curve. In contrast, 5 mg/kg prednisolone caused alterations in diaphragmatic contractile properties and histological changes without fiber atrophy.

Long-term use of oseltamivir for the prophylaxis of influenza in a vaccinated frail older population.

OBJECTIVES: To investigate the efficacy of once-daily oral oseltamivir for 6 weeks (Tamiflu) in prophylaxis against laboratory-confirmed clinical influenza in frail older subjects living in homes for seniors and to determine the safety and tolerability of long-term oseltamivir. DESIGN: Double-blind, placebo-controlled, parallel-group, randomized, multicenter study. SETTING: Thirty-one residential homes for seniors across United States and Europe. PARTICIPANTS: Five hundred forty-eight frail older occupants (mean age 81 years, >80% vaccinated). INTERVENTION: Prophylaxis with oseltamivir 75 mg or placebo once daily for 6 weeks, beginning when influenza was detected locally. MEASUREMENTS: The primary efficacy endpoint was laboratory-confirmed clinical influenza. RESULTS: Oseltamivir administration resulted in a 92% reduction in the incidence of laboratory-confirmed clinical influenza compared with placebo (placebo 12/272 (4.4%), oseltamivir 1/276 (0.4%); P = .002). Of subjects vaccinated against influenza, oseltamivir was 91% effective in preventing laboratory-confirmed clinical influenza (placebo 11/218 (5.0%), oseltamivir 1/222 (0.5%); P = .003). Oseltamivir use was associated with a significant reduction in the incidence of secondary complications (placebo 7/272 (2.6%), oseltamivir 1/276 (0.4%); P = .037). Although nearly all subjects were taking concomitant medication both before and during the study, oseltamivir was well tolerated. A similar incidence of adverse events, including gastrointestinal effects, occurred in both groups. There was no suppression of antibody response in oseltamivir recipients. CONCLUSION: Oral oseltamivir 75 mg once daily for 6 weeks effectively prevented clinical influenza in vaccinated frail older subjects using significant concomitant medications in a residential care setting. The treatment was well tolerated and provided additional protection to that afforded by vaccination.

Effects of unilateral vagal stimulation on intrapulmonary neuroepithelial bodies.

We studied the influence of unilateral vagal stimulation on intrapulmonary neuroepithelial bodies (NEB) in rabbits. The left vagus nerve was cut and electrically stimulated for 10 min. Animals were killed and the lungs studied with fluorescence and electron microscopy. Intensity of formaldehyde-induced fluorescence, which reflects the serotonin content in NEB, was higher on the stimulated side than on the nonstimulated side (118 +/- 7 vs. 100%, n = 8, P less than 0.001). The latter difference was found to correlate with the stimulus amplitude (r = 0.9, P less than 0.05). Ultrastructurally a decrease in the number of exocytotic dense-cored vesicle (DCV) profiles at the level of the NEB basal epithelial cell membrane was found on the stimulated side (0.32 +/- 0.10 vs. 0.45 +/- 0.16 DCV/micron of basal epithelial cell membrane, n = 8, P less than 0.05). Section of the left vagus nerve without electrical stimulation affected neither the fluorescence intensity nor the number of exocytotic DCV profiles. In animals with supranodosal or infranodosal chronic vagotomy the observed effects of unilateral vagal stimulation were no longer present. We conclude that 1) vagal stimulation increases the serotonin content of NEB; 2) it decreases the number of exocytotic DCV profiles; 3) this effect depends on the amplitude of the stimulus; 4) it is obtained through efferent vagal fibers; 5) these results are the opposite of the effects seen after exposing normal NEB to acute hypoxia; and 6) these physiological experiments corroborate a vagal innervation of NEB, which may play an important role in modulating the sensitivity and reaction of NEB to various stimuli.

Theophylline minimally alters contractile properties of canine diaphragm in vitro.

We examined the effects of theophylline on contractile properties and high-frequency fatigue of canine diaphragm in vitro. Eighteen diaphragm muscle bundles were obtained from 10 anesthetized dogs and equilibrated in oxygenated Krebs solution to 100, 200, or 300 mg/l theophylline. These bundles were compared with 18 matched control bundles from the contralateral hemidiaphragm. No statistically significant differences in twitch tension, tetanic tension, twitch-to-tetanus ratio, time to peak tension, or half-relaxation time were observed. Concentrations of 300 mg/l theophylline, however, significantly (P less than 0.05) increased force production at 10 Hz by 32%. A similar tendency was present at lower concentrations and exhibited a clear dose-response behavior. High-frequency fatigue was similar in control and theophylline-treated bundles. We conclude that supratherapeutic in vitro concentrations of theophylline do not increase maximal tetanic tension and do not protect against muscle fatigue but potentiate relative force production at low stimulation frequencies. This relatively small effect cannot be explained by poor diffusion of the drug in the muscle bundle, because theophylline concentrations in the muscle bath and in the muscle bundle were virtually identical. Moreover, it remains unclear whether this potentially beneficial effect can be achieved at in vivo attainable serum concentrations.

Corticosteroid treatment and nutritional deprivation cause a different pattern of atrophy in rat diaphragm.

Triamcinolone (TR) causes type IIb fiber atrophy in the rat diaphragm, which is associated with changes in contractile properties. We investigated whether this is a direct effect of TR or the result of an accompanying loss of body and diaphragm weights. For 6 wk, adult rats received saline intramuscularly, TR (0.5 mg/kg im), or nutritional depletion (ND) that resulted in a similar (approximately 40%) reduction in body weight as TR. In these animals, the half-relaxation time of the diaphragm bundles increased, the force-frequency relationship shifted leftward, and the resistance to fatigue was increased. No histological changes were found in the ND diaphragm, in contrast to severe myogenic alterations in the TR diaphragm. Type IIb fiber cross-sectional area (CSA) in the TR diaphragm was reduced by 51%, whereas type I and IIa CSAs were unaffected. In the ND animals, the CSAs of type I, IIa, and IIb fibers were reduced by 31, 33, and 52%, respectively. Similar changes occurred in the deep part of the m. gastrocnemius. In conclusion, myogenic changes and selective type IIb fiber atrophy were caused by TR, whereas ND induced generalized fiber type atrophy without histological changes.

Effects of nandrolone decanoate on respiratory and peripheral muscles in male and female rats.

Thirty male and 18 female adult rats received weekly an intramuscular injection of either saline (control; C), 1.5 mg/kg (low-dose; LD) nandrolone decanoate or 7.5 mg/kg (high-dose; HD) nandrolone decanoate during 5 wk. Compared with respective C, growth rate was stunted in male HD rats from 2 wk of treatment on, whereas it was enhanced in female LD and HD rats after 1 wk. Mass of all muscles studied varied proportionally to body weight, except for the gastrocnemius (males: 0.49 +/- 0.04 vs. C: 0.52 +/- 0.03%, not significant; females: 0.17 +/- 0.01 vs. C: 0.15 +/- 0.01%, P < 0.05). In vitro contractile and fatigue properties of the diaphragm remained unchanged, except for a decrease in twitch kinetics (time to peak tension: C, 21 +/- 2; LD, 19 +/- 1; HD, 19 +/- 2 ms, P < 0.05; half-relaxation time: C, 26 +/- 5, LD, 25 +/- 5, HD, 23 +/- 3 ms, P < 0.01). Histochemistry of the diaphragm and the gastrocnemius revealed a significant increase in type IIx/b dimensions. In the gastrocnemius, type I fiber dimensions also increased. A pair-fed study, including another 24 female rats, showed that the changes in oral food intake only partly accounted for the observed anabolic effects.

Bombesin-like peptides in human small cell carcinoma of the lung.

The nature of bombesin-like immunoreactive peptides was studied in extracts of small cell carcinoma of the human lung. Three peaks, I, II and III, designated by their increasing retention times, were separated by reversed-phase high performance liquid chromatography (HPLC) with trifluoroacetic acid (TFA) as counter ion. None of the peaks corresponded to bombesin. Peak III was eluted at the same position as porcine gastrin releasing peptide (GRP) but was separated from it in another reversed-phase system using heptafluorobutyric acid (HFBA). Peak II material eluted in the position of bombesin in the HFBA system but not in the TFA system. The elution position of Peak I corresponded to that of the carboxyl terminal fragments of GRP, i.e. GRP18-27 and GRP19-27. This correspondence was observed in each of the reversed-phase and gel filtration systems used. The Peak III peptide was converted to peak I after incubation with trypsin. It was reasoned that this conversion could be one of the steps in the processing of bombesin-like peptides in human small cell carcinoma.

Serotonin content of rabbit lung and small intestine during perinatal development.

Serotonin (5-hydroxytryptamine, or 5HT) was measured in extracts of rabbit lung and intestine during perinatal development using high pressure liquid chromatography (HPLC) with electrochemical detection. Lung and intestine were extracted with HClo4 and the extract was loaded onto a Bio-Rex 70 resin column. After elution with acetic acid the samples were injected onto the HPLC column. Serotonin was detected in lung and intestine at 18 days of gestation (80 and 90 ng/mg protein). In lung serotonin content increased at day 28 (290 ng/mg protein) till day 30 (680 ng/mg protein) decreased at day 1 after birth (480 ng/mg protein) and then rose at day 10 of the newborn period (650 ng/mg protein). In intestine the serotonin content was always higher than in the lung. At the end of gestation the serotonin in the intestine remained constant (2410 ng/mg protein at day 28 and 2430 ng/mg protein at day 30), decreased slightly one day after birth (2150 ng/mg protein) and rose at day 10 (3300 ng/mg protein).

Origin of bombesin-like peptides in human fetal lung.

Four different forms of bombesin-like immunoreactive peaks were detected in extracts of human fetal lung by the use of reversed-phase high performance liquid chromatography (HPLC). Peaks I, II, III and IV, (increasing retention time), were eluted using a 14-38% of acetonitrile gradient containing 0.1% trifluoroacetic acid (TFA). Peak II was the major material found in the extract of human fetal lung obtained at 16-20 weeks gestation. None of the four compounds contained in the eluted peaks had the same retention time as amphibian bombesin or porcine gastrin releasing peptide (GRP). On reversed-phase HPLC using two different solvent systems TFA or heptafluorobutyric acid (HFBA) as a hydrophobic counter ion, and in gel filtration chromatography, the chromatographic behavior of the main peak (peak II) was the same as that of the carboxyl terminal fragments of GRP, GRP18-27 or GRP19-27. This suggested that the peptide(s) in peak II resembled in composition the carboxy terminal 9 or 10 amino acids of porcine GRP. Following tryptic digestion the material in peak IV was converted to the more polar compound present in peak II. Two other peptide peaks were eluted close to peak II and these were presumed to be a modification of this main peak. One of the possible biosynthetic steps in the formation of bombesin-like peptides in human fetal lung could be a tryptic conversion of a less polar peptide to a more polar form (peak IV to II).

Clostridium difficile infection in a geriatric ward.

In a prospective, longitudinal study we searched for the presence of Clostridium difficile in the stools of 100 consecutively hospitalized elderly patients (mean age: 82; SD: 9.5 years). C. difficile was found on admission in 6 patients, 3 of whom were asymptomatic carriers. Ten patients acquired C. difficile during hospitalization. Four different types of C. difficile were isolated. The various types were clustered in time, indicating that the infection was acquired from the environment.

Functional and histologic picture of steroid-induced myopathy in chronic obstructive pulmonary disease.

The functional and histologic picture of steroid-induced myopathy was systematically examined in eight patients with chronic obstructive pulmonary disease (COPD) and compared with control patients with COPD matched for age, sex, and degree of airflow obstruction. Steroid-induced myopathy was associated with severe peripheral muscle weakness, quadriceps force being 23 +/- 14 versus 71 +/- 23% in control patients with COPD (p < 0.001). In addition, clear ventilatory muscle weakness was present. PImax was 37 +/- 15 versus 67 +/- 24% in control patients (p < 0.001 ), and PEmax averaged 34 +/- 10 versus 74 +/- 23% (p < 0.001). Vital capacity tended to be slightly reduced compared with that in control patients (69 +/- 21 versus 80 +/- 16%, p = 0.11). The only biochemical abnormalities associated to steroid-induced myopathy were a moderately increased lactic dehydrogenase level (697 +/- 301 versus 421 +/- 128 IU/L, p < 0.001) and an increased creatine excretion in 24-h urine (990 +/- 609 versus 159 +/- 219 mg/24 h, p< 0.001). On quadriceps biopsy steroid-induced myopathy was characterized by increased variation in diameter of fibers, with several angular atrophic fibers and diffuse necrotic and basophilic fibers. In addition, increased amount of connective tissue in between fibers and increased number of subsarcolemmal and central nuclei were present. On ATPase stain diffuse fiber atrophy predominantly affecting fast fibers was present, but there was no indication that atrophy was confined to type IIb fibers in contrast to conventional thinking. On follow-up, survival of patients with steroid-induced myopathy was reduced in comparison with control patients with COPD with similar degree of airflow obstruction (p < 0.025).

Pharmacokinetics of vancomycin in patients undergoing haemodialysis and haemofiltration.

Vancomycin is widely used for the treatment of infections with Gram-positive bacteria in patients with end-stage renal disease. The concentration of vancomycin in serum, in ultrafiltrate, and in dialysate was measured during nine haemofiltration and seven haemodialysis procedures with high-permeability membranes. The t1/2 of vancomycin was 101 +/- 19 h in the interdialytic and interhaemofiltration period. There was no significant difference between the haemodialysis clearance (55.2 +/- 18.5 ml/min) and the haemofiltration clearance (66.8 +/- 13.6 ml/min). The redistribution phenomenon was about 25% in the post haemofiltration period and only 10% in the post haemodialysis period. Approximately 270 mg of vancomycin was recovered in dialysate or ultrafiltrate. With high-permeability membranes more commonly used in patients with end-stage renal disease, continuous monitoring of vancomycin therapy is recommended.

Theophylline alters distribution of blood flow to respiratory muscles.

This study was designed to examine the effects of theophylline on respiratory muscle blood flow in 11 lightly anesthetized and spontaneously breathing dogs using the radioactive microsphere tracer technique. During quiet breathing, blood flow to the costal diaphragm (25.1 +/- 13.9 ml/100 g/min) exceeded blood flow to the parasternal intercostals (18.0 +/- 10.2 ml/100 g/min, p < 0.05). Inspiratory resistive loading abolished these differences by increasing blood flow to the parasternal intercostals more than to the diaphragm. Aminophylline (40 mg/kg) significantly increased minute ventilation and tidal transdiaphragmatic pressure (Pdi) swing during quiet breathing but not during inspiratory resistive loading. Theophylline did not affect diaphragmatic blood flow during inspiratory resistive loading while the same Pdi swing and tension-time index (TTdi) were reached. During quiet breathing, however, theophylline significantly (p < 0.05) increased blood flow to the triangularis sterni from 7.9 +/- 5.6 to 18.1 +/- 25.6 ml/100 g/min and to the transversus abdominis from 10.8 +/- 8.4 to 14.6 +/- 10.5 ml/100 g/min and tended to increase blood flow to the costal diaphragm and the parasternals. We conclude that (1) during quiet breathing, but not during inspiratory resistive loading, blood flow to the costal diaphragm exceeded flow to the parasternal intercostals; (2) during quiet breathing, theophylline increased blood flow to the expiratory muscles as it promoted recruitment of expiratory muscles; and (3) theophylline did not affect diaphragmatic blood flow for a given TTdi.

Captopril treatment of chronic heart failure in the very old.

BACKGROUND: The safety and efficacy of angiotensin-converting enzyme inhibitors for very old patients with chronic heart failure have been less well documented than for younger patients. METHODS: A prospective, randomized double-blind, placebo-controlled study of captopril, 25 mg twice daily, was designed. Fifty patients (mean age 84.2 +/- 5.2) participated. The degree of chronic heart failure (according to the Boston Study Group rating), the distance walked in 6 minutes, and the occurrence of uncontrolled heart failure and adverse reactions were used as main outcome measures. RESULTS: Significantly more patients receiving placebo developed uncontrolled heart failure than patients receiving captopril (p = .022). In an intention to treat analysis, the first and last evaluations of the degree of chronic heart failure were compared. A significantly different evolution was observed between the two treatment groups (p < .001), with a significant improvement only in the captopril-treated patients (p < .001). The distance walked in 6 minutes improved significantly only in the captopril group (p = .004). The only adverse reaction was rash in two patients receiving captopril. CONCLUSIONS: The study gives further evidence that angiotensin-converting enzyme inhibitor treatment for very old patients with chronic heart failure is useful.

Broxaterol increases force output of fatigued canine diaphragm more than salbutamol.

We previously demonstrated that broxaterol enhanced recovery of fatigued canine diaphragm. The aim of this study was to compare the inotropic effects of salbutamol and broxaterol on fatigued canine diaphragm. Low-frequency fatigue was induced in 14 mongrel dogs by electrophrenic stimulation, which was continued until transdiaphragmatic pressure (Pdi) at 20 Hz was reduced by 50% or for 1 h. After stabilization of fatigue, the animals received a bolus (18.5 microg/kg) of either broxaterol or salbutamol, followed by a continuous infusion (0.43 microg/kg/min). A second bolus of 74.0 microg/kg, followed by a continuous infusion of 1.72 microg/kg/min, was given after 90 min. Both drugs significantly increased twitch Pdi. Twitch Pdi measured 90 min after the first and second doses of broxaterol increased by 28 +/- 23% and 42 +/- 34%, respectively, whereas the salbutamol-induced increase was clearly smaller (9 +/- 10% and 17 +/- 15%, respectively). Broxaterol increased Pdi at 20 Hz by 25 +/- 28% with the first dose and by 29 +/- 21% with the second dose. In contrast, salbutamol did not alter Pdi at 20 Hz. Neither drug affected Pdi at 100 Hz. We conclude that broxaterol promoted recovery of low-frequency fatigue of the canine diaphragm in vivo in a dose-dependent manner, whereas salbutamol only minimally improved force production by the fatigued diaphragm.

Immunohistochemical localization of serotonin in intrapulmonary neuro-epithelial bodies.

A recently developed immunohistochemical technique for serotonin (Steinbusch et al. 1978) was used in the present investigation to study the occurrence of this indoleamine in the granulated epithelial cells of neuro-epithelial bodies (NEB). Lungs from neonatal rabbits and pigs exhibit immunoreactive cell groups identical in morphology and their preferential location (i.e., at bronchiolar bifurcations) to the recently described intrapulmonary NEB. Moreover, in the trachea and lung of rabbits isolated immunoreactive cells, presumably of Kultschitsky type, were found in the lining respiratory mucosa. Such single cells were also frequently observed in the bronchial epithelium of pig lungs. It is concluded that the corpuscular cells, being modulated by the central nervous system, probably represent intrapulmonary neuro(chemo-)receptors with local secretory activities, one of the substances released being serotonin and reacting to the oxygen composition of the inhaled air. It is proposed that the cells of Kultschitsky type exert a more local effect upon the airways.

Effects of unilateral hypoxia on neuroepithelial bodies in rabbit lungs.

The present study was undertaken to investigate the influence of regional (unilateral) alveolar hypoxia on the intrapulmonary neuroepithelial bodies (NEB), which contain bioactive substances and are distinctly innervated. Eight (4-wk-old) rabbits were subjected to unilateral hypoxia. The animals were anesthetized by an intramuscular injection of Hypnorm and breathed spontaneously during the experiment. The right lung received a hypoxic gas mixture (10% O2-90% N2) and the left lung a hyperoxic mixture. Blood gas measurements indicated that no systemic hypoxemia or acidosis occurred under these conditions. Lung samples were examined by electron microscopy to determine morphometrically the extent of a secretory exocytosis at the basal cell pole of the NEB and by a microspectrographical analysis of the formaldehyde-induced fluorescence to quantify the NEB serotonin content. After 20 min of unilateral hypoxia the NEB in the right hypoxic lung exhibited an increased exocytosis and a lower serotonin content in comparison with the left hyperoxic lung NEB. These results indicate that NEB react to regional alveolar hypoxia by secreting serotonin and/or peptides to the surrounding lung tissue (blood vessels, smooth muscle, nerve endings, etc.).

Rat diaphragm contractility and histopathology are affected differently by low dose treatment with methylprednisolone and deflazacort.

The extent to which treatment with low doses of the nonfluorinated steroid methylprednisolone affects diaphragm contractility and morphology is unknown. In the present study, we compared the effects of equipotent doses of methylprednisolone and deflazacort, an oxazoline derivate of prednisolone with less systemic side-effects on bone structure and carbohydrate metabolism. Twenty six male adult rats were randomized to receive daily saline (control), methylprednisolone 0.4 mg.kg-1 or deflazacort 0.5 mg.kg-1 i.m. Contractile properties and histopathology were measured after a 6 week treatment period. During treatment, body weight increased in control and methylprednisolone-treated animals, but decreased by 4.2 +/- 1.1% (mean +/- SD) in the deflazacort group. Similarly, diaphragm mass in the deflazacort group was decreased compared to control and methylprednisolone groups. Twitch tension and twitch characteristics of isolated diaphragm bundles were similar in the three groups. Maximal tetanic tension was decreased in the deflazacort group. The force-frequency curve of the deflazacort bundles shifted downwards compared to control. Fatigue occurring during this protocol was greatest in the methylprednisolone- and deflazacort-treated animals. Microscopic examination revealed no gross abnormalities in the three groups. Histochemical analysis after staining for myosin adenosine triphosphatase (ATP-ase) showed that in the deflazacort group cross-sectional area of type I, IIa and IIb fibres were decreased. We conclude that low doses of methylprednisolone caused subtle and negligible changes in rat diaphragm contractile properties without affecting fibre dimensions, while deflazacort at an equipotent dose induced generalized fibre atrophy and changes in diaphragm contractility.

Recovery of corticosteroid-induced changes in contractile properties and morphology of rat diaphragm.

Treatment with the fluorinated steroid triamcinolone (TR) induced type IIb fiber atrophy and the contractile profile of a slow muscle in rat diaphragm. In contrast, the nonfluorinated steroid prednisolone (PR) caused myogenic changes without fiber atrophy, and increased fatigability. The aim of the present study was to investigate the extent to which these changes were reversed 2 mo after discontinuation of treatment. Adult rats were randomly assigned to receive saline, PR 1.25 or 5 mg/kg, or TR 0.25, 0.5, or 1 mg/kg, intramuscularly daily during 4 wk. Administration of TR resulted in severe loss of body weight and dose-dependent mortality. During recovery, body weight in the TR groups increased gradually, still remaining reduced compared with the other groups. Two months after discontinuation of treatment, diaphragm weight was increased in proportion to body weight. Twitch characteristics, maximal tetanic force, force-frequency curve, and fatigue resistance of isolated diaphragm bundles were similar in all groups. Histologic examination of the diaphragm revealed no gross abnormalities in the PR and TR groups. Mild but significant type IIb fiber atrophy was still present in the diaphragm and gastrocnemius muscle of all TR-treated animals. In conclusion, recovery of alterations in morphology of respiratory and peripheral skeletal muscles induced by administration of TR is prolonged.