- Email: [email protected]
MYOCARDIAL OXYGEN CONSUMPTION OR AVAILABILITY
403 similar immune responses in the two study groups. The fact that seroconversion rates to tetanus, diphtheria, and measles vaccines were high among children in both groups does not support this hypothesis. The results of these two studies do not suggest that the immune response to the vaccines used in routine immunisation schedules is depressed by weekly chemoprophylaxis with chloroquine, but they need to be confirmed. Medical Research Council Laboratories, Fajara, Banjul, Gambia
B. M. GREENWOOD
HM, Greenwood BM, Greenwood AM, et al The Malumfashi project-an epidemiological, clinical and laboratory study. Trans Roy Soc Trop Med Hyg 1983;
1. Gilles
77: 24-31.
Bradley-Moore AM, Greenwood BM, Bradley AK, et al Malaria chemoprophylaxis with chloroquine in young Nigerian children II: Effect on the immune response to vaccination. Ann Trop Med Parasitol (in press). 3. Greenwood AM, Greenwood BM, Bradley AK, Ball PAJ, Gilles HM. Enhancement of the immune response to meningococcal polysaccharide vaccine in a malaria endemic area by administration of chloroquine. Ann Trop Med Parasitol 1981; 75: 261-63. 2
COHORT STUDY OF FORMALDEHYDE PROCESS WORKERS
Fig I-Preoperative heart-rate changes in a man of 64 with coronaryartery disease.
17 paper (p 611) we presented the mortality of a cohort of 7680 men who had been employed before
SiR,-In our March
experience
1965 in factories where formaldehyde was produced or used. One of the main reasons for setting up this study was the observation that formaldehyde produced malignant tumours of the nasal cavities in rats exposed to high concentrations. Our paper reported no deaths from nasal cancer compared with 1 - 07 expected among the cohort by the end of 1981, although altogether 1626 men had died. The April issue of Health and Safety at Work suggested that our study is inadequate, because it did not include information on morbidity. However, we have been informed of non-fatal cancer cases among men in this study through the national cancer registration scheme, and no living cases of nasal cancer have been notified to us. Our letter of May 12 (p 1066) mentioned our plan to do casecontrol studies of smoking and previous employment among the lung cancer cases and controls in one of the factories. Unfortunately, the information available in the factory records has proved scanty. Among 128 lung cancer cases and 640 controls (5 matched to each case) whose records, including medical records, were searched for smoking habits only 4 contained any relevant information. For previous employment 87 (15 cases, 72 controls) men had some information recorded. When these data were analysed by industry and occupation, there were no discernible differences between the cases and controls. In both groups the major industry mentioned was the manufacture ofmetal products, where 8 (53%) of the cases and 38 (53%) of the controls had previously worked. In view of the inadequacy of these further studies our previous conclusions remain unchanged. We are continuing to follow up this cohort of workers, together with men who entered the same factories after 1964. These will be reported on in due course.
MRC Environmental Epidemiology Unit Southampton General Hospital,
Southampton SO94XY ’Present address’ Department of Health and Social Security,
E. D. ACHESON* H. R. BARNES M. J. GARDNER C. OSMOND B. PANNETT C. P. TAYLOR I. London SE1.
Kerns WD, Mitchell RI, Gralla EJ, Pavkov KL. Induction of squamous cell carcinoma of the rat nasal cavity by inhalation exposure to formaldehyde vapour. Cancer Res 1980; 40: 3398-402.
1 Swenberg JA,
MYOCARDIAL OXYGEN CONSUMPTION OR AVAILABILITY
Fig 2-Postoperative
secondarily to hypoxia. Episodes of nocturnal ST depression may indicate a decrease in oxygen availability rather than an increase in myocardial oxygen demands. The mechanisms may not always be equivalent to the changes seen in daytime angina, as suggested by Quyyumi and colleagues. Department of Medicine, Guy’s Hospital,
JOHN REES
Department of Medicine,
nocturnal
St Bartholomew’s London EC1
nocturnal ischaemia. We have recorded ECG and measured
Department of Cardiology, Guy’s Hospital, London
myocardial ischaemia. They conclude that increases in myocardial oxygen consumption are important in precipitating
changes.
airflow at nose and mouth, chest-wall movement, and ear-oxygen saturation in a number of similar patients. In several patients STsegment changes have been related to decreases in ear-oxygen saturation related to hypoventilation. Fig 1 shows ST depression and heart-rate changes in a man of 64 with severe coronary-artery disease. These changes were associated with episodes of hypoventilation and desaturation. Sleep apnoea was not present. Coronary angiography demonstrated -severe lesions in the left main stem and right coronary arteries, and a triple coronary-artery-bypass graft was carried out. The nocturnal study was repeated postoperatively (fig 2). Periods of hypoventilation and desaturation were more pronounced than those in the preoperative trace, but there was no evidence of the corresponding changes in heart-rate or ST segments seen before operation. Therefore, the primary change in this patient was hypoventilation with electrocardiographic changes developing only
London SE19RT
SiR,-Dr Quyyumi and colleagues (June 2, p 1207) documented the changes in heart-rate and ST-segment depression in daytime and
heart-rate
Hospital,
WYN DAVIES
PAUL CURRY
B. M. GREENWOOD
HM, Greenwood BM, Greenwood AM, et al The Malumfashi project-an epidemiological, clinical and laboratory study. Trans Roy Soc Trop Med Hyg 1983;
1. Gilles
77: 24-31.
Bradley-Moore AM, Greenwood BM, Bradley AK, et al Malaria chemoprophylaxis with chloroquine in young Nigerian children II: Effect on the immune response to vaccination. Ann Trop Med Parasitol (in press). 3. Greenwood AM, Greenwood BM, Bradley AK, Ball PAJ, Gilles HM. Enhancement of the immune response to meningococcal polysaccharide vaccine in a malaria endemic area by administration of chloroquine. Ann Trop Med Parasitol 1981; 75: 261-63. 2
COHORT STUDY OF FORMALDEHYDE PROCESS WORKERS
Fig I-Preoperative heart-rate changes in a man of 64 with coronaryartery disease.
17 paper (p 611) we presented the mortality of a cohort of 7680 men who had been employed before
SiR,-In our March
experience
1965 in factories where formaldehyde was produced or used. One of the main reasons for setting up this study was the observation that formaldehyde produced malignant tumours of the nasal cavities in rats exposed to high concentrations. Our paper reported no deaths from nasal cancer compared with 1 - 07 expected among the cohort by the end of 1981, although altogether 1626 men had died. The April issue of Health and Safety at Work suggested that our study is inadequate, because it did not include information on morbidity. However, we have been informed of non-fatal cancer cases among men in this study through the national cancer registration scheme, and no living cases of nasal cancer have been notified to us. Our letter of May 12 (p 1066) mentioned our plan to do casecontrol studies of smoking and previous employment among the lung cancer cases and controls in one of the factories. Unfortunately, the information available in the factory records has proved scanty. Among 128 lung cancer cases and 640 controls (5 matched to each case) whose records, including medical records, were searched for smoking habits only 4 contained any relevant information. For previous employment 87 (15 cases, 72 controls) men had some information recorded. When these data were analysed by industry and occupation, there were no discernible differences between the cases and controls. In both groups the major industry mentioned was the manufacture ofmetal products, where 8 (53%) of the cases and 38 (53%) of the controls had previously worked. In view of the inadequacy of these further studies our previous conclusions remain unchanged. We are continuing to follow up this cohort of workers, together with men who entered the same factories after 1964. These will be reported on in due course.
MRC Environmental Epidemiology Unit Southampton General Hospital,
Southampton SO94XY ’Present address’ Department of Health and Social Security,
E. D. ACHESON* H. R. BARNES M. J. GARDNER C. OSMOND B. PANNETT C. P. TAYLOR I. London SE1.
Kerns WD, Mitchell RI, Gralla EJ, Pavkov KL. Induction of squamous cell carcinoma of the rat nasal cavity by inhalation exposure to formaldehyde vapour. Cancer Res 1980; 40: 3398-402.
1 Swenberg JA,
MYOCARDIAL OXYGEN CONSUMPTION OR AVAILABILITY
Fig 2-Postoperative
secondarily to hypoxia. Episodes of nocturnal ST depression may indicate a decrease in oxygen availability rather than an increase in myocardial oxygen demands. The mechanisms may not always be equivalent to the changes seen in daytime angina, as suggested by Quyyumi and colleagues. Department of Medicine, Guy’s Hospital,
JOHN REES
Department of Medicine,
nocturnal
St Bartholomew’s London EC1
nocturnal ischaemia. We have recorded ECG and measured
Department of Cardiology, Guy’s Hospital, London
myocardial ischaemia. They conclude that increases in myocardial oxygen consumption are important in precipitating
changes.
airflow at nose and mouth, chest-wall movement, and ear-oxygen saturation in a number of similar patients. In several patients STsegment changes have been related to decreases in ear-oxygen saturation related to hypoventilation. Fig 1 shows ST depression and heart-rate changes in a man of 64 with severe coronary-artery disease. These changes were associated with episodes of hypoventilation and desaturation. Sleep apnoea was not present. Coronary angiography demonstrated -severe lesions in the left main stem and right coronary arteries, and a triple coronary-artery-bypass graft was carried out. The nocturnal study was repeated postoperatively (fig 2). Periods of hypoventilation and desaturation were more pronounced than those in the preoperative trace, but there was no evidence of the corresponding changes in heart-rate or ST segments seen before operation. Therefore, the primary change in this patient was hypoventilation with electrocardiographic changes developing only
London SE19RT
SiR,-Dr Quyyumi and colleagues (June 2, p 1207) documented the changes in heart-rate and ST-segment depression in daytime and
heart-rate
Hospital,
WYN DAVIES
PAUL CURRY