Biomedical subjects
A A Kerr
Publications and source records attributed to A A Kerr.
The mutagenicity of emissions from eight binder systems used in steel foundries.
Emissions generated when molten steel was poured into sand molds fabricated with eight different binder systems were collected separately and tested for mutagenic activity using the Ames Salmonella assay. The sampling device consisted of an initial 8 X 10 in. glass fiber filter in a custom fabricated apparatus through which air was drawn using a Hi-Vol motor and fan. A portion of the airstream, which passed this filter, was in turn passed through a smaller glass fiber filter and then into two glass impingers filled with ice-cold methanol. All the binder systems generated material, which induced mutations in the absence of added S-9 extract, and in all emissions a higher level of activity was found when S-9 was added. In the presence of S-9, the shell-core system produced by far the most mutagenic activity followed by the oil-clay-cereal system. The green sand, furan and Kold Set systems produced much lower levels while the two reclaimed sand systems and sodium silicate system were intermediate.
Identification of polycyclic aromatic compounds in mutagenic emissions from steel casting.
Workers in ferrous foundries show increased risk of lung cancer. In the steel casting process hot metal is poured into sand moulds solidified with organic binders, producing a plume of smoke containing a variety of organic compounds and showing strong mutagenicity in the Salmonella/S9 assay. We have collected the emissions produced when steel is poured into an experimental sand mould solidified with oil, clay and cereal, a widely used binder system. The organic constituents of these emissions have been fractionated by preparative reverse-phase high performance liquid chromatography (HPLC) and mutagenic fractions have been analysed by capillary column gas chromatography/mass spectrometry (GC/MS). Of the 65 compounds for which mass spectra are reported, 54 have been tentatively identified as alkyl derivatives of polycyclic aromatic compounds. Many compounds of this class are known to be carcinogenic and mutagenic. In addition, several unsubstituted polycyclic aromatic hydrocarbons, including the carcinogenic benz[a]anthracene and benzo[a]pyrene, were found to be present.
Management of lower respiratory tract infections in infants.
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Delayed skin hypersensitivity reaction in normal children.
The delayed skin hypersensitivity reaction was assessed in normal children using candida, PPD and sterptokinase/streptodornase antigens. There was an increase in reactivity from 20 percent in children under three years to 90 percent in the 12--16 age group which approximates adult levels. The conclusion is that this test of cell-mediated immunity is unsatisfactory in young children.
Recurrent respiratory disease in Polynesian children.
Studies were performed on 13 Polynesian children who suffered from recurrent respiratory disease characterised by cough, wheeze, tachypnoea and radiological opacities. Only one was substantially underweight. Most had iron deficiency anaemia. Serum IgG levels were high with a less definite trend to raised IgA and IgM levels. Precipitating antibodies to cow's milk protein were found in 6 out of 10 children tested who were currently on cow's milk feeds. The proportion of rosette-forming lymphocytes was reduced in 8 of the 12 tested. The Mantoux test using using 10 TU of PPD was negative in 7 out of 10 children who had had BCG in the newborn period. The likelihood of cow's milk contributing to the respiratory disease in these children is discussed.
Lung function in children after repair of congenital diaphragmatic hernia.
Sixteen children who had had congenital diaphragmatic herniae repaired either in the neonatal period (11), or in early childhood (5), were reviewed at between 7 and 19 years of age. Only minor abnormalities were shown in their chest x-rays and in a variety of lung function tests. This suggests that the long-term prognosis in this condition is good.
The effect of positive end expiratory pressure on lung mechanics and arterial oxygenation after open heart surgery in young children.
The effect of positive end expiratory pressure (PEEP) during mechanical ventilation of the lungs was measured in 10 young children, aged 3 weeks to 30 months, who were being ventilated artificially after cardiopulmonary bypass surgery. Changes in the end-tidal lung volume were measured directly using a jacket plethysmograph, and were assumed to indicate change in functional residual capacity (FRC). Simultaneous changes in compliance and blood-gases were measured also. FRC was increased in all subjects, and in most this increase was accompanied by an increase in arterial oxygenation. There was no significant alteration in the mean values of dynamic or static compliance in the group, although dynamic compliance increased during PEEP in six patients. PEEP may be of value after cardiopulmonary bypass in young children when oxygenation is poor despite high inspired oxygen fractions. The possible mechanisms by which it increases PaO2 are discussed.
Dead space ventilation in normal children and children with obstructive airways diease.
Anatomical dead space was measured in 72 normal children aged from 5 to 16 years, using the single breath method. There was a linear increase in this measurement with height, weight, and end-inspiratory lung volume. Physiological dead space was measured in 52 normal children using the Bohr equation and substituting a rebreathing PCO2 for alveolar PCO2. There was a parallel increase in this measurement with height, weight, and end-inspiratory lung volume. The difference between the two dead space measurements constitutes the alveolar dead space and was constant over the whole age range at 45 +/- 22 ml. The ratio of physiological dead space to tidal volume was 33-6 +/-4-6% and was unaltered by age or change in lung volume. The effect of airways obstruction on the dead space volumes was studied in 36 children with asthma and 28 with cystic fibrosis. Physiological dead space increased with increasing airways obstruction. Anatomical dead space remained constant in spite of marked increases in lung volume associated with the airways obstruction.
Gastric 'flu influenza B causing abdominal symptons in children.
Influenza-B virus was identified in 102 children admitted to hospital during two epidemics in 1973 and 1974, enzbling the symptomatology of infection with this virus to be assessed in detail for the first time. Abdominal pain, often severe enough to require differentiation from acute appendicitis, emerged as a dominant symptom, especially in older children. Respiratory symptoms were often insignificant, although the lower respiratory tract was sometimes involved. Other symptoms in some children included convulsions and acute myalgia. The immunofluorescent method of virus diagnosis was found to be reliable for influenza B, except in a few cases ehere nasopharyngeal secretions were scanty, giving 97-5 percent copositivity with standard isolation techniques. The rapid result provided by immunofluorescence was helpful in clinical diagnosis and management and also in the control of hospital cross-infection.
Change in end-tidal position in children after suxamethonium.
The change in end-tidal position (ETP) after suxamethonium-induced paralysis was measured in 15 children during routine general anaesthesia. In all patients the onset of muscle paralysis was associated with an increase in lung volume from ETP. This increase may be the result of paralysis of the expiratory muscles which are active during anaesthesia.
Effects of continuous positive airway pressure on lung mechanics of babies after operation for congenital heart disease.
The effect of continuous positive airway pressure (CPAP) on lung mechanics was investigated in 12 babies after operation for severe congenital heart disease. At the time of study all babies were receiving or being weaned from ventilatory support and had abnormally low lung volume or compliance. During CPAP there was a fall in the pulmonary resistance which, with a slight decrease in minute ventilation, resulted in a significant decrease in the work of breathing. It is suggested that lowering the oxygen cost of breathing may contribute to the improvement in arterial oxygenation seen when CPAP is used.
Proceedings: Closing volumes in childhood.
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Proceedings: Effect of continuous positive airway pressure on the lung mechanics of babies with congenital heart disease.
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Continuous positive-airway pressure after open-heart operations in infancy.
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Ascension of the testis after correction of kyphoscoliosis.
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Neonatal colonic perforation after exchange transfusion: a case report.
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