Experimental production of respiratory tract disease in cebus monkeys after intratracheal or intranasal infection with influenza A/Victoria/3/75 or influenza A/New Jersey/76 virus.
A total of 28 cebus monkeys were inoculated intratracheally or intranasally with 10(6) 50% tissue culture infective doses of A/New Jersey/76 virus or 10(7) 50% tissue culture infective doses of A/Victoria/75 virus, and 8 additional monkeys received sterile allantoic fluid. Each of the animals became infected as evidenced by a serological response and/or shedding of the virus. Of the 10 animals inoculated intratracheally with A/Victoria/75 virus, 8 developed a systemic illness, and pulmonary infiltration was detected by X-ray in 7 of the 8. Administration of A/New Jersey/76 virus intratracheally to 10 monkeys produced a mild systemic illness in 2 animals and an upper respiratory tract illness in 6, but no illness developed in the remaining 2 monkeys; none of the animals developed X-ray evidence of lower respiratory tract disease. Intranasal administration of either virus failed to induce any illness or produced, at most, mild illness confined to the upper respiratory tract. These studies demonstrate that cebus monkeys are susceptible to respiratory tract infection with influenza A viruses and that the development of pulmonary disease is reflected in the appearance of easily recognizable radiological changes. (+info)
Inhalation exposure of animals.
Relative advantages and disadvantages and important design criteria for various exposure methods are presented. Five types of exposures are discussed: whole-body chambers, head-only exposures, nose or mouth-only methods, lung-only exposures, and partial-lung exposures. Design considerations covered include: air cleaning and conditioning; construction materials; losses of exposure materials; evenness of exposure; sampling biases; animal observation and care; noise and vibration control, safe exhausts, chamber loading, reliability, pressure fluctuations; neck seals, masks, animal restraint methods; and animal comfort. Ethical considerations in use of animals in inhalation experiments are also discussed. (+info)
Antibiotic resistance of nasopharyngeal isolates of Streptococcus pneumoniae from children in Lesotho.
Villages associated with the Lesotho Highlands Development Agency were randomized with a bias in favour of larger villages, and children < 5 years of age from cluster-randomized households in these villages were chosen for the assessment of antibiotic resistance in pneumococci. Children of the same age group attending clinics in the capital, Maseru, were selected for comparison. Nasopharyngeal cultures of Streptococcus pneumoniae from both groups of children were examined for antibiotic resistance and a questionnaire was used to assess risk factors for the acquisition of resistant strains. Carriage of penicillin- and tetracycline-resistant pneumococci was significantly higher among 196 Maseru children compared with 324 rural children (P < 0.05 and P = 0.01, respectively). Maseru children tended to visit clinics at an earlier age compared with their rural counterparts. The rural children were less exposed to antibiotics (P < 0.01), were less frequently hospitalized (P < 0.001), and rarely attended day care centres (P < 0.001). The very low incidence of antibiotic resistance in rural Lesotho and the higher incidence in Maseru are in stark contrast with the much higher frequencies found in the Republic of South Africa, many European countries, and the USA. (+info)
Comparison of cephalometric analysis using a non-radiographic sonic digitizer (DigiGraph Workstation) with conventional radiography.
Cephalometric analysis conventionally requires radiographic exposure which may not be compatible with the growing concern over radiation hazards. Recently, the Dolphin Workstation Imaging System introduced to the dental profession a non-radiographic system, called the DigiGraph Workstation which may be an alternative to cephalometric radiography. The aims of this study were to compare the validity and reproducibility of cephalometric measurements obtained from the DigiGraph Workstation with conventional cephalometric radiographs. The sample consisted of 30 human dry skulls. Two replicated sets of lateral cephalograms were obtained with steel ball markers placed at the majority of the cephalometric landmarks. Duplicate tracings prepared from each radiograph were digitized to obtain cephalometric measurements using the computer software, Dentofacial Planner. For the DigiGraph Workstation, double sonic digitizations were repeated twice for each skull, on two occasions. Fifteen angular and one linear measurements were obtained from both methods and these findings compared using ANOVA, paired t-tests and F-tests. All, except one, cephalometric measurement showed significant differences between the two methods (P < 0.0001). The DigiGraph Workstation consistently produced higher values in 11 measurements (mean differences +0.5 to +15.7 degrees or mm) and lower values in four measurements (mean differences -0.2 to -3.5 degrees). The standard deviations of the differences between readings of both methods were large (0.4-5.8 degrees or mm). The reproducibility of the DigiGraph Workstation measurements was lower than that of the radiographic measurements. The method error of the DigiGraph Workstation ranged from 7 to 70 per cent, while that of radiographic tracings was less than 2 per cent. It was concluded that measurements obtained with the DigiGraph Workstation should be interpreted with caution. (+info)
Impact of nasal ventilation on survival in hypercapnic Duchenne muscular dystrophy.
BACKGROUND: Respiratory failure is the commonest cause of death in patients with Duchenne muscular dystrophy (DMD). Life expectancy is less than one year once diurnal hypercapnia develops. This study examines the effects of nasal intermittent positive pressure ventilation (NIPPV) on survival in symptomatic Duchenne patients with established ventilatory failure. METHODS: Nocturnal NIPPV was applied in 23 consecutive patients with DMD of mean (SD) age 20.3 (3.4) years who presented with diurnal and nocturnal hypercapnia. RESULTS: One year and five year survival rates were 85% (95% CI 69 to 100) and 73% (95% CI 53 to 94), respectively. Early changes in arterial blood gas tensions following NIPPV occurred with mean (SD) PO2 increasing from 7.6 (2.1) kPa to 10.8 (1.3) kPa and mean (SD) PCO2 falling from 10.3 (4.5) kPa to 6.1 (1.0) kPa. Improvements in arterial blood gas tensions were maintained over five years. Health perception and social aspects of SF-36 health related quality of life index were reported as equivalent to other groups with nonprogressive disorders using NIPPV. CONCLUSIONS: Nasal ventilation is likely to increase survival in hypercapnic patients with Duchenne muscular dystrophy and should be considered as a treatment option when ventilatory failure develops. (+info)
Efficacy of nasal continuous positive airway pressure therapy in chronic heart failure: importance of underlying cardiac rhythm.
BACKGROUND: Some previous reports have indicated beneficial cardiac effects of nasal continuous positive airway pressure (NCPAP) in patients with severe congestive heart failure (CHF), but others have reported deleterious cardiac effects, particularly among patients in atrial fibrillation (AF). The aim of this study was to determine if differences in cardiac rhythm influence the acute cardiac response to NCPAP. METHODS: Eleven consecutive patients with CHF were recruited, six in atrial fibrillation (AF) and five with sinus rhythm (SR). Cardiac index was measured during awake NCPAP application by the thermodilution technique during cardiac catheterisation. NCPAP was applied in a randomised sequence at pressures of 0, 5, and 10 cm H2O with three 30 minute applications separated by 20 minute recovery periods without NCPAP. RESULTS: Significant differences were found between the AF and SR groups for cardiac index responses to NCPAP (p = 0.004, ANOVA) with a fall in cardiac index in the AF group (p = 0.02) and a trend towards an increase in the SR group (p = 0.10). Similar differences were seen between the groups in stroke volume index responses but not in heart rate responses. Changes in systemic vascular resistance were also significantly different between the two groups (p < 0.005, ANOVA), rising in the AF group but falling in the SR group. CONCLUSIONS: These data indicate an important effect of underlying cardiac rhythm on the awake haemodynamic effects of NCPAP in patients with CHF. (+info)
Effect on nasal resistance of an external nasal splint and isotonic exercise.
OBJECTIVES: The now commonplace wearing of external nasal splints by sportsmen and athletes has never been scientifically evaluated. The present study looks into the effect of isotonic exercise on nasal resistance, and examines whether this effect is altered by the wearing of an external nasal splint. METHODS: Twenty subjects not suffering from rhinitis were tested. Nasal resistance measurements were recorded using an anterior rhinomanometer before and after isotonic exercise with and without an external nasal splint. Pulse and blood pressure were measured before and after exercise. RESULTS: Significant changes were observed in pulse (p < 0.001) and both systolic (p < 0.002) and diastolic (p < 0.001) blood pressure in response to exercise. Significant differences were seen in nasal resistance when the splint was applied (p < 0.001) and after exercise (p < 0.003). No significant difference was observed after exercise when the splint was worn (p = 0.167). CONCLUSIONS: External nasal splints decrease nasal resistance at rest but are of little value during isotonic exercise. (+info)
Reverse transcription-competitive multiplex PCR improves quantification of mRNA in clinical samples--application to the low abundance CFTR mRNA.
BACKGROUND: To monitor gene therapy, we wished to quantify cystic fibrosis transmembrane conductance regulator (CFTR) mRNA. We developed a PCR-based method to measure CFTR mRNA in clinical samples. METHODS: Expression was determined by reverse transcription-competitive multiplex PCR (RCMP) for CFTR and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) transcripts, and for serial dilutions of two internal cDNA standards consisting of CFTR and GAPDH mutants containing short deletions. The RCMP used simultaneous amplification of the gene of interest with a reporter gene in one reaction tube. The expression of CFTR was calculated with reference to the amount of GAPDH to correct for variations in initial RNA loading. RESULTS: Amplification of cDNAs derived from different amounts of RNA (1-4 microgram) gave similar GAPDH/CFTR ratios, with a coefficient of variation (CV) below 7.5%. RCMP was applied on nasal and bronchial brushings and shows a high variability of CFTR expression in non-cystic fibrosis donors. CONCLUSION: This method is precise and reproducible and advantageous for use with limited amounts of tissue, such as from biopsies or from nasal or bronchial brushings. (+info)