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Biomedical subjects

B Robertson

Publications and source records attributed to B Robertson.

At least 325 records · Page 18Linked to original sources
PubMed1983

Demonstration of spinocerebellar projections in cat using anterograde transport of WGA-HRP, with some observations on spinomesencephalic and spinothalamic projections.

Wheat germ agglutinin-horseradish peroxidase (WGA-HRP) conjugate was injected into the lumbar or cervical spinal cord of adult cats in order to examine its usefulness as an anterograde tracer of long ascending spinal tracts. Heavily labeled fibers and terminal-like structures were found in restricted regions of the granular layer of the cerebellar cortex in all animals. The terminal-like structures showed features characteristic of mossy fiber rosettes. Many labeled terminals were found in regions anatomically and physiologically defined as cerebellar hind limb regions after lumbar cord injections. Relatively few labeled terminals were found in both hind limb and in forelimb regions after cervical cord injections. Although the cervical spinal cord is known to project to both hind limb and forelimb regions, it cannot be entirely excluded that some of the labeling in the hind limb regions was derived from uptake by fibers of passage. In addition to labeling in the cerebellar cortex, labeled fibers and terminals were also observed in the cerebellar medial and interposed nuclei, regardless of whether the injections had been made into the lumbar or the cervical spinal cord. Several midbrain and thalamic regions were found to contain labeled fibers and terminal-like profiles in all cases. In the midbrain the periaqueductal gray, the nucleus of Darkschewitsch and the posterior pretectal nucleus contained fairly dense labeling. Labeling was more scattered in the cuneiform nucleus, the mesencephalic reticular formation, the superior colliculus and in the magnocellular part of the medial geniculate body.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Rabbit lung after inhalation of soluble nickel. II. Effects on lung tissue and phospholipids.

Rabbits were exposed to soluble nickel chloride, about 0.3 mg/m3 as nickel, for about 1 month (5 days/week, 6 hr/day). The upper lobe in the left lung was examined with light microscopy and samples from the left lower lobe with electron microscopy. Nodular accumulation of macrophages and laminated structures occurred in alveoli of all exposed rabbits, but otherwise no inflammatory reactions. Volume density of the alveolar epithelial type II cells was doubled due to increased cell number as well as cell volume. The tissue content of phospholipids, determined in the lower lobe of the left lung, had increased by about 40%, mainly due to elevated disaturated phosphatidylcholines. The effect pattern was almost identical to that seen earlier in inhalation experiments with metallic nickel dust, strongly indicating that nickel ions are responsible also for the changes seen after exposure to metallic nickel. This suggests that all nickel compounds may produce the pathological condition, which is similar to that seen in the disease pulmonary alveolar proteinosis.

Aerosols↗
PubMed1983

Rabbit lungs after long-term exposure to low nickel dust concentration. I. Effects on phospholipid concentration and surfactant activity.

Rabbits were exposed for 4 or 8 months (5 days/week, 6 hr/day) to 0.13 +/- 0.05 mg/m3 (mean +/- SD) of metallic nickel dust. After exposure the left lung was homogenized and its content of phospholipids as well as the concentration and composition of the phosphatidylcholines were estimated. The right lung was lavaged and the surface tension of the lavage fluid was studied with a pulsating bubble technique. Both exposed groups showed a similar increase in total phospholipids, about 20% in the upper lobe and 30% in the lower lobe. The increase was mainly, possibly totally, due to an elevated level of phosphatidylcholines, especially disaturated species. Surface tension was significantly lower in exposed rabbits after 4 months of exposure but it was similar to that of the controls after 8 months.

Animals↗
PubMed1983

Experimental partial ureteric obstruction in newborn rats. IV. Do the morphological effects progress continuously?

Partial obstruction of the ureter was created in newborn rats, and its effects were studied after 1, 2, 3, 6 and 9 weeks--that is, until adult age. Within 1 week, a considerable hydronephrosis had appeared. Within 2 weeks, parenchymal weight was found slightly reduced (8 per cent) on the obstructed side, and, within 3 weeks, equivalently increased on the contralateral, intact side. After these points in time, there was no further deterioration. Histological examination revealed marked deformation of the papilla and minor foci of degeneration and inflammation within 1 to 2 weeks which tended to become chronic in type after 3 to 9 weeks. Arterial hypertension was not noted. Thus, the effects of partial ureteric obstruction on the renal parenchyma are 1) discrete, 2) not in proportion to the degree of hydronephrosis, 3) fully compensated by contralateral hypertrophy and 4), after reaching an early maximum, not increasing with time.

Aging↗
PubMed1983

Automated techniques for the study of lung alveolar stereological parameters with the IBAS image analyser on optical microscopy sections.

In the case of lung alveoli, the good contrast of the features allows the use of a fully automated image analysing procedure, yielding many of the desirable stereological parameters which can be estimated on optical microscopy slides: alveolar volume and surface densities, a form factor and average mean integral curvature. With our program, specially designed for the IBAS image analyser (Kontron Bildanalyse, Munich, B.R.D.), the whole automated process takes an average of 28 s per field. The image analyser-obtained stereological estimates compare well with those given by point and intersection counting methods. Some difficulties inherent in image analysers arise when measuring alveolar boundary lengths: a scheme is therefore proposed which eliminates the image-edge errors, with no sampling bias, by comparing three different frames inside each field. A solution to the problem of estimating automatically the positive and negative tangent counts, necessary for the curvature calculations, is also proposed. Our program has been applied routinely to the study of premature newborn rabbit lung alveoli, as part of a work dealing with an evaluation of the possibility of preventing the respiratory distress syndrome by the administration of heterologous surfactant.

Animals↗
PubMed1983

Lung surfactant for replacement therapy.

In recent years, several attempts have been made to treat, or prevent, the neonatal respiratory distress syndrome (RDS) with exogenous surfactants. The most successful clinical trial so far reported concerned a series of artificially ventilated RDS-patients who were treated with a mixture of bovine natural surfactant and the synthetic phospholipids dipalmitoylphosphatidylcholine (DPPC) and unsaturated phosphatidylglycerol (PG). The rationale of this combination is that enrichment of natural surfactant with DPPC and PG strikingly modifies the lin vitro surface properties of the surfactant preparation, reducing surface tension to very low values already at moderate surface compression. In other similar clinical trials, promising results have been obtained with natural surfactant suspended with CaCl2, with human surfactant purified from amniotic fluid, and with protein-free natural surfactant from bovine lungs. Encouraging results have also been reported from a recent trial in which a dry, artificial surfactant, composed of DPPC and unsaturated PG, was administered prophylactically into the airways of premature babies shortly after birth. More studies, involving a combination of in vitro and in vivo experiments, are nevertheless needed to identify the optimal composition of an artificial surfactant and to evaluate the long-term effects of surfactant replacement on the premature lung.

Amniotic Fluid↗
PubMed1983

Zinc, copper, magnesium, and calcium in blood and plasma after phlebotomy.

Zinc levels in plasma and whole blood were investigated in 2 groups of blood donors. The first group consisted of 19 men and 11 women who donated blood for the first time and were followed during 3 phlebotomies. The second group comprised 44 men with 9 or more previous blood donations, their blood being analysed on a single occasion. Plasma concentrations of copper, magnesium, calcium and ferritin were also analysed. The zinc levels in whole blood and plasma in the second group were significantly lower as compared to the first group (P less than 0.001). Furthermore, the second group had significantly higher levels of copper and copper:zinc quotient in plasma as compared to those of the new blood donors (P less than 0.001). Our results indicate that besides the earlier known effect of blood donation on iron stores, there are also signs of zinc depletion when judged from the zinc levels in plasma and in erythrocytes. No significant changes in calcium and magnesium concentrations were seen during phlebotomy.

Adolescent↗
PubMed1983

Surface adsorption of pulmonary surfactant in relation to bulk-phase concentration and presence of CaCl2.

The adsorption rate of natural surfactant lipids was studied with a surface balance at 37 degrees C, with particular reference to the influence of various bulk-phase concentrations and to the presence of CaCl2. On a hypophase of 0.9% NaCl, natural surfactant had rapid adsorption (1-5 s) in concentrations greater than or equal to 0.5 mg/ml, whereas lipids extracted from the same surfactant showed a comparable adsorption rate only in concentrations greater than or equal to 3.5 mg/ml. This indicates that natural surfactant contains some not yet identified nonlipid component enhancing the adsorption rate. On a hypophase of 0.9% NaCl + 0.05% CaCl2, the adsorption rate of extracted surfactant lipids was similar to that of natural surfactant on 0.9% NaCl. The concentration of surfactant phospholipids in fetal pulmonary fluid at term is about 0.6 mg/ml; our data suggest that at this concentration the adsorption of natural surfactant does not require the presence of bivalent cations to spread effectively in an air-liquid interface.

Adsorption↗
PubMed1982

The use of anterogradely transported wheat germ agglutinin-horseradish peroxidase conjugate to visualize cutaneous sensory nerve endings.

Small amounts of wheat germ agglutinin-horseradish peroxidase conjugate were injected into the L5 spinal ganglion of adult rats. The conjugate was transported peripherally by the sensory neurons to their cutaneous receptors in the hind paw. Nerve plexa in the skin were heavily labeled, and different types of nerve endings could be clearly distinguished. This method gives new possibilities to study peripheral fibers and nerve endings originating in single sensory ganglia.

Animals↗
PubMed1982

Combined effects of surfactant substitution and prolongation of inspiration phase in artificially ventilated premature newborn rabbits.

Premature newborn rabbits, delivered by hysterotomy on day 27 of gestation, were tracheotomized at birth, kept in body plethysmographs, and subjected to pressure-generated ventilation at a working pressure of 25 cm H2O, 100% O2, and frequency 40/min. Thirty-seven animals received 50 microliters of heterologous surfactant (phospholipid content 40 mg/ml) via the tracheal cannula before onset of artificial ventilation, eight were ventilated with a positive end-expiratory pressure (PEEP) of 6 cm H2O, and 44 served as controls. All animals were ventilated in a randomized sequence of 2-min periods with 20, 40, 60, or 80% inspiration time. After the experiment the trachea was clamped at end-inspiration and the lungs fixed by immersion in formalin. Plethysmograph recordings of tidal volume revealed that lung-thorax compliance was low in control animals, even at inspiration time 80% (mean +/- S.E. = 0.17 +/- 0.03 ml/cm H2O X kg). In animals treated with surfactant or PEEP, compliance was significantly improved at all ventilator settings. The highest mean compliance values, obtained at 60% inspiration time were 0.91 +/- 0.07 and 0.73 +/- 0.14 ml/cm H2O X kg in surfactant- and PEEP-treated animals, respectively. Compliance of surfactant-treated animals was significantly higher than that of PEEP-treated animals at inspiration time 40% (0.85 +/- 0.07 versus 0.52 +/- 0.13 ml/cm H2O X kg; P less than 0.05). The relative volume of the alveolar compartment, determined morphometrically in histologic sections and expressed as the alveolar expansion index (Ia), was significantly higher in surfactant-treated animals than in controls (1.60 +/- 0.12 versus 0.74 +/- 0.06; P less than 0.005), but not improved in animals ventilated with PEEP. In animals receiving surfactant, Ia increased with the duration of the inspiration phase, from 0.99 +/- 0.10 at 20% to 1.95 +/- 0.22 at 80% inspiration time. There was also histologic evidence of enhanced recruitment of aerated alveoli in surfactant-treated animals ventilated with prolonged inspiration time.

Animals↗
PubMed1982

[The effect of intermittent hydrogen chloride exposure on the lung function of the guinea pig].

23 guinea pigs were exposed to 15 mg/m3 HCl gas 5 days/week, 2 hours daily, for 7 weeks. 15 animals served as controls. From the 5th day of exposure, the following lung function parameters were evaluated in anaesthetised animals: VT, fR, minute volume, TGV, Vmax, R1, Rw, Rrs, Cl, Cw, Crs, delta Poes/VT, hemoglobin, SaO2, PaO2, PaCO2, pH, SBC, BE. These measurements showed no differences between HCl-exposed animals and controls. Histological examination of the lungs revealed no changes which could be attributed to HCl-exposure. This study relates to the important question whether lung damage can be induced by industrially produced, intermittent high levels of HCl in the environment.

Animals↗
PubMed1981

Effect of supplementary surfactant on in vivo lung mechanics in the premature rabbit neonate.

Premature newborn rabbits, delivered on day 27 of gestation, were subjected to positive-pressure ventilation, with or without treatment with natural surfactant. The surfactant, obtained by centrifugation of lung wash from adult rabbits, was deposited in the tracheal cannula before the onset of ventilation. Parameters of lung mechanisms, recorded during spontaneous ventilation after 1 h, were significantly improved in animals receiving surfactant. In comparison with littermate controls, surfactant-treated animals also had less prominent bronchiolar epithelial lesions. We conclude that treatment with supplementary surfactant facilitates functional adaptation of the premature lung and prevents the development of epithelial lung lesions during artificial ventilation.

Animals↗