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Biomedical subjects

N Wald

Publications and source records attributed to N Wald.

At least 127 records · Page 7Linked to original sources
PubMed1975

Effect of gestational age on screening for neural-tube defects by maternal plasma-A.F.P. measurement.

Maternal plasma or serum alpha-feto-protein (A.F.P.) concentrations were measured once between 8 and 22 weeks of gestation in each of sixty-two pregnancies which resulted in an infant with a neural-tube defect. Between 13 and 22 weeks of pregnancy twenty-two of the forty-one cases tested (54%) had A.F.P. values greater than three times the median value for unaffected pregnancies (which is equivalent to the 97th percentile of normal), and many of these values were very high indeed. However, before the 13th week of pregnancy only one of the twenty-one cases (5%) had an A.F.P. value more than three times the median for unaffected pregnancies, and this value was not very high. This indicates that in antenatal screening for anencephaly or spina bifida, A.F.P. should be measured in blood taken from the mother during the second trimester.

Anencephaly↗
PubMed1975

Maternal serum alpha-fetoprotein levels in multiple pregnancy.

Maternal serum alpha-fetoprotein (AFP) levels were higher in 10 twin pregnancies and one triplet pregnancy than in 22 control singleton pregnancies matched for maternal age, parity, and the time of gestation at which the serum sample was taken. In twin pregnancies the average AFP levels were double those found in singleton pregnancies and the level in the triplet pregnancy was even higher. Raised maternal serum AFP values due to multiple pregnancy should not cause unnecessary amniocentesis in the diagnosis of anencephaly or spina bifida if an ultrasound investigation is routinely performed first.

Adult↗
PubMed1975

Use of carboxyhaemoglobin levels to predict the development of diseases associated with cigarette smoking.

Carboxyhaemoglobin (COHb) levels in tobacco smokers vary throughout the day since they are affected by the pattern of tobacco consumption and the rate at which COHb is eliminated. A method is described whereby a single COHb measurement together with a recent smoking history may be used to estimate the average COHb "boost" produced by each cigarette, the total daily carbon monoxide (CO) uptake from smoking, and the mean COHb level throughout the day. These three indices of tobacco smoke absorption were estimated in nine healthy cigarette smokers on different days, each set of three estimations being derived from separate COHb determinations. The indices were reasonably reproducible within the same person, and the differences between people were statistically highly significant (P less than 0-001). For example, the estimates of mean daily COHb level resulting from smoking ranged from 0-7% to 9-3% in smokers who smoked 15 to 40 cigarettes a day. These differences are sufficiently large to distinguish possible differences in the risk of developing diseases such as ischaemic heart disease which may result from the inhalation and absorption of tobacco smoke. The suggested indices also depend less on the time of the blood test and on the daily pattern of smoking than a COHb level alone. The ratio of the COHb boost to the CO yield of a cigarrette may reflect depth of inhalation more accurately than a smoker's self-assessment. Moreover there was little correlation between these two measures of inhalation in the nine subjects studied.

Carbon Monoxide↗
PubMed1975

Chromosomal abnormalities in progressive systemic sclerosis (scleroderma) with consideration of radiation effects.

An increased frequency of cytogenetic aberrations was observed in 63 patients with progressive systemic sclerosis (PSS, scleroderma). The most striking finding was the appearance of compound aberrations (chromosomal fragments and rearrangements) in PSS patients, while none were found in the control subjects. The aberrations were nonspecific in nature. The frequency of aberrations in the PSS patients was elevated above that of other patients receiving similar diagnostic radiation exposure (less than 1 R to greater than 10 R), but showed no relation to the amount of irradiation. The dose-response relation may have been obscured by the narrow range of exposures or by a "breakage factor" newly reported in such patients. It appears that in PSS patients the increased chromosomal breakage is not associated with an elevated frequency of leukemia or other neoplasms such as has been reported to be associated with other nonspecific breakage syndromes.

Adult↗
PubMed1973

Association between atherosclerotic diseases and carboxyhaemoglobin levels in tobacco smokers.

In a cross-sectional study carboxyhaemoglobin (COHb) levels in tobacco smokers were found to provide a better indication of a person's risk of having developed certain atherosclerotic diseases, including ischaemic heart disease, than the smoking history. In the age group 30-69 years a person with a COHb level of 5% or more was found to be 21 times (lower 95% confidence limit 3.3 times) as likely to be affected by these diseases as another person of the same age and sex with similar smoking history and current smoking habits but with a COHb level of less than 3%.

Age Factors↗