Animal experimental model for studying respiratory and cardiovascular parameters in unanaesthetized rabbits

The purpose of the study was to examine the reproducibility of measurements of respiratory and cardiovascular functions in unanaesthetized rabbits. Observed coefficient of variations (CV) and hence the reproducibilities of different measurements in the present study were highly comparable to values reported for anaesthetized rabbits. So it could be concluded that anaesthetization is not a prerequisite to study respiratory and cardiovascular function in rabbits.

Reversible fraction of airway resistance in healthy children of areas with different levels of atmospheric pollutants

Reversible fraction of airway resistance (delta Raw) has been defined as the difference between airway resistances (Raw) before and after inhalative treatment with ipratropium-bromide (Atrovent) aerosols in healthy subjects. We examined delta Raw in children between 6-8 years of age living in areas with different air qualities. We found small but statistically significant (p less than 0.1) greater delta Raw for children of higher polluted areas. This could indicate that children of polluted areas possessed higher bronchial smooth muscle tone.

[Lung function and carboxyhemoglobin during the smog episode of January 1987]

During a phase of elevated ambient air pollution in January 1987 the alert level of the smog alarm recommendation in Northrhine Westfalia (FRG) was reached. The average concentrations during examinations were 0.255 mg/m3 SO2 and 3.2 mg/m3 CO at the closest station. In 111 healthy persons in Cologne and Düsseldorf, resistance measured by oscillatory method was elevated during this period compared to control examinations. In 59 patients with moderate airway-obstruction from different parts of West Germany lung function showed further deterioration during the smog phase: Airway resistance measured by body-plethysmography was higher than during a control period, FVC, FEV1, PEF and MEF75 were decreased. Finally levels of carboxyhemoglobin in blood also were increased in 46 healthy nonsmokers. The investigation shows, that even in moderate smog episodes (compared to earlier years) small, but consistent changes of lung function parameter can be measured.

Neutron scattering cross sections and partial kerma values for oxygen, nitrogen and calcium at 18 less than En less than 60 MeV

Recent measurements of differential elastic and inelastic neutron scattering from oxygen, nitrogen and calcium at 18 less than En less than 26 MeV are presented and analysed in terms of the optical model. These data, together with earlier measurements of scattering and total cross sections, are used to construct model potentials that may be used to calculate various quantities of interest in neutron dosimetry in an energy region (20-60 MeV) where very few cross section data are available. The heavy-ion-recoil contribution to kerma is obtained directly from the data at each energy. The value of proton inelastic scattering data for validating potential models at high energy is discussed.

Standardization of different spirometers

This study was designed to compare spirometers used for human testing and to determine whether the results obtained by different spirometers meeting the American Thoracic Society (ATS) requirements are interchangeable. Water-sealed spirometer (Harvard), dry bellow wedge spirometer (Vitalograph) and computerized pneumotachograph (Gould), all of them satisfying the ATS recommendations were compared. Forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), forced expired flow between 25 and 75% of FVC (FEF 25-75%) and 100 FEV1/FVC (FEV1%) were selected for comparative analysis. Measurements of these parameters were carried out on a total of 40 healthy volunteers of mixed nationalities. The Vitalograph values for FVC, FEV1 and FEV1% were significantly higher than those of the water-sealed spirometer (Harvard), but were closely similar to the values obtained by the Gould computerized pneumotachograph. Our results thus do not support the interchangeability of different spirometers and stress the importance of biological standardization of spirometers against each other.

Cell-biology of ageing. III. Malondialdehyde as an index of free radical reactions in the early senescent mutants of Neurospora crassa and study of the effect of free radical scavengers on malondialdehyde contents

Malondialdehyde - a product of lipid peroxidation due to free radical reaction was estimated in the culture filtrates of early senescent mutants of Neurospora crassa and the effects of vitamin E, vitamin C and Sodium selenite (free radical scavengers) in malondialdehyde contents were studied. From the results obtained, it could not be established that increased free radical reaction was the sole factor for the early senescence of all the mutants; and the free radical scavengers had very little effect on the malondialdehyde content of the selected early senescent mutants.

Influence of the inhalative aerosol Atrovent on airway resistance and intrathoracic gas volume in healthy volunteers of different ages

53 healthy volunteers of different age groups were included in this study. Airway resistance (Rt) and intrathoracic gas volume (IGV) were measured with volume constant bodyplethysmograph before and 15, 30, 60 and 120 min after a 1-min exposure to Atrovent aerosol. There were statistically significant reductions in Rt in all four groups (group I: 4-11 years; group II: 18-30 years; group III: 32-45 years; group IV: 47-54 years) of volunteers. Statistically significant reductions in IGV were observed in groups I and II. Group III also showed reduction in IGV, but it was not statistically significant. In contrast we found light but statistically significant increase in IGV in group IV. When the values of Rt were computed as specific airway conductance, then the increases following atrovent aerosols were statistically significant only in groups I, II and IV, but not in group III. It is concluded that smooth muscle tones, as evident from Rt reductions following atrovent inhalation, were not uniform in all individuals and that age plays an important role in this mechanism. However, it is not clear whether nervous components alone or the physicochemical nature of smooth muscles are also the controlling factors.

Myelinogenic cycle and myelination status of the brain of the catfish, Heteropneustes fossilis

The lipid composition of the brain of the catfish, Heteropneustes fossilis (Bloch) was studied over the age period of 2-12 months, during which time the body weight increased from 2.5 to 33 g. The brain weight increased from 28 to 84 mg between 2 and 9 months of age, with a further increase of only 7 mg during the following three months. The concentration of cholesterol increased slowly up to 5 months of age, from which time the concentration began to increase rapidly and attained adult values at 8 months. The concentration of total lipid-P increased steadily up to the age of 7 months and remained almost constant thereafter. In contrast, there was very little increase in the concentration of the galactolipids (cerebroside + sulphatide) until month 5, after which the concentration increased rapidly to reach the adult level at 8 months of age. The concentration of cholesterol esters decreased during development; however, there occurred a transient rise at 5 months of age, which continued up to 8 months. These data indicate that the period between months 5 and 8 is one of active myelination in the brain of this species. The mole ratio of cholesterol, phospholipids, and galactolipids in the adult fish brain was 31:53:1, much higher than that in adult mammalian brain. Moreover, within the phospholipids, ethanolamine phosphoglyceride comprised < 10%, as against the corresponding value in the mammals of about 40%. These data therefore suggest a low level of myelination in the brain of catfish, as compared to that in higher species.

Role of vagus nerves and inhalative aerosols of acetylcholine and histamine on dynamic pulmonary elastance in anesthetized spontaneously breathing and artificially ventilated dog

The role of the vagus nerves on resting respiratory resistance (R1) and dynamic lung elastance (Edyn) and the mechanism of action of inhaled aerosol of histamine (Hist) and acetylcholine (ACH) were studied in anesthetized spontaneously breathing and artificially ventilated dogs. Observations were also extended to study the effect of electrical stimuli to cut ends of both vagi alone and during inhalation of aerosols. Bilateral cervical vagal blockade by local application of novocaine solution (2.5%) or bilateral vagotomy reduced resting R1 and Edyn and prevented increase of these parameters following inhalation of aerosols of Hist or ACH in spontaneously breathing dogs. However, the similar vagal blockade or vagotomy in artificially ventilated animals showed neither an influence on resting R1 and Edyn nor could it prevent their increase following the exposure to aerosol of Hist or ACH. Electrical stimuli to the peripheral cut ends of vagi induced slight increase in R1 and Edyn, but the effect on heart rate and systemic blood pressure was very strong. The combined effects of aerosol of Hist or ACH and electrical stimuli were additive. It is concluded that inhalation of aerosol of Hist or ACH produced two kinds of effects on respiration: (1) Increased respiratory rates with reduced tidal volume and with bronchoconstriction which were vagus-dependent (spontaneous breathing model), and (2) bronchoconstriction which was a direct response of smooth muscle without involving a reflex (artificial ventilation model).

The effect of thyroxine, the antithyroid drug propylthiouracil and thyroidectomy on mineral metabolism in rat tissues

The administration of thyroxine produces a significant increase in the copper, magnesium, iron and zinc contents of liver, with a concomitant decrease of heart iron. Magnesium in heart tissues was also increased. The administration of antithyroid drugs produces a significant decrease in the concentration of the same metals in the liver with concomitant increases in kidney copper and calcium, and in heart magnesium and calcium. Brain magnesium was found to be significantly decreased after antithyroid treatment and increased to a lesser extent after thyroxine administration. Thyroidectomy did not produce an appreciable effect on minerals in various tissues, except heart zinc which was significantly decreased. These findings suggest the involvement of thyroid hormones in tissue mineral metabolism, especially in the liver.