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Bigger babies booming
THE LANCET
Biomarkers from and NASA budgets for Mars
T
he evidence behind recent “Life on Mars” headlines appears this week in Science. Ex-life off that planet is a fairer summary. David S McKay and his colleagues - from the US
- 4500 million years - 15 million years - 13 thousand years - 20 years - 14 years - 12 years - 2 years zero (1996) + 1year + 5 years + 9 years
Antarctica where it was found in 1984. It is the largest of 12 martian meteorites found on earth identified as such by the close match between the gases trapped in them and data
__
ALH 84001 matc?rialformed Asteroid hits Mairs. ejecting ALH84001 into space Meteorite lands iin Antarctica Viking Mars landing experiments Recognition of fii’st lunar meteorite ~ ~ ~ 8 4founc 0 01 1 ALH84001 ident ified as probably martian. Mars Observer missioii fails Report of relic biogenic activity, in Science Landings of Mar!j surveys despatched this year ?joint US/Russi a launch ? return of marti;an geological material
explanation too; furthermore, the hydrocarbons were found deep in the specimen. There has been controversy over whether the carbonates can only form in high temperature processes, too high to be compatible with any sort of “life”. However, isotope and other evidence now points to the process occurring at temperatures in the 0-80 “C range. The scientists also looked at the carbonate globules in detail, adding two more threads of evidence to the ‘‘life’’ claim-namely, the presence of iron compounds of possible biogenic origin, and electronmicroscopic features resembling those found in concretions grown from Pleistocene groundwater and “interpreted as representing nanobacteria”. What next? According to an anticipated report from the Committee on Planetary and Lunar Exploration (Nature 1996; 382: 481), NASA’s current budget may not allow for the bringing back to Earth of maman material of the sort that would permit more direct confirmation of the recent claim. If President Clinton’s response to the meteorite’s contents is anything to go by, ALH84001 may do wonders for NASA.
National Aeronautics and Space Administration, having carefully discussed what they found in an Antarctic meteorite supposedly of martian origin, say that they have evidence for “primitive life on early Mars”(Science 1996;273: 924-30). The Viking probes had recorded no evidence of organic material in martian surface “soil” and no evidence for fossils either. McKay et a1 have been looking at something much closer to home, a meteorite known as ALH84001, after the Allan Hills in
recorded by the Viking experiments. -84001 is rich in carbonates, unlike other meteorites of this class, and it was in regions of the meteorite high in carbonates that simple polycyclic hydrocarbons were found (eg. phenanthrene, pyrene, chrysene, and anthracene), the first evidence for organic molecules in martian rock. But could this be terrestrial contamination? McKay and colleagues are confident about their handling of the material. Industrial contamination in the Antarctic is an improbable
Bigger babies booming
Coronary artery disease: the folate link
T .
I.
he growth charts used by most Amencan physicians to monitor child progress are outdated and need revision, says a paper in Arch Pedian Adolesc Med (1996;150: 842-49) Helen Binns (Children’s Memorial Hospital, Chicago, USA) and colleagues from the area Pediatric Practice Research Group studied 1574 healthy term infants born in Chicago in the mid 1980s, and compared their growth with standard growth curves provided by the National Center for Health Statistics, based on data collected from a sample of 867 infants born between 1929 and 1975. The average PPRG baby weighed about 3.4 kg at birth-about 0.2 kg more for girls and about 0.13 kg more for boys than the NCHS norm. “Because the PPRG curves are shifted up, use of the NCHS curves to plot the weight of PPRG infants would result in under identification of underweight infants and over identification of overweight infants”, write the authors. 0
464
ncreased homocysteine concentrauons have gained recent attention as a potentially modifiable risk factor for coronary heart disease (CAD). Several calls have now been made for randomised controlled trials of folate supplements to lower plasma homocysteine levels (see Lancer, June 29, ~1823).But a Hong Kong study on southern Chinese, a population with an increasing prevalence of CAD, is a reminder that studies seeking to define the role of diet must also pay close attention to other risk factors. In this study (Heart 1996; 76: 1 17-22), significantly increased postmethionine-loading test homocysteinaemia (hyperHcy) was found in patients with angiographically proven CAD compared with healthy volunteers. People with hyperHcy had significantly higher folate concentrations than normoHcy individuals. Other studies have found significant negative correlations between hyperHcy and folate-suggesting a role for folate supplements.
David Sham
In the Hong Kong study, 16 of 17 patients with CAD and hyperHcy smoked compared with only 9 of 28 CAD patients with normal methionine-loading tests. Smoking, however, rather than hyperHcy was the only independent risk factor for CAD on multivariate analysis, say the authors. It is well established that severe hyperHcy is associated with premature vascular disease although the mechanism by which altered homocysteine metabolism causes vascular damage is uncertain. Other factors affect homocysteine such as sex, smoking, blood pressure, and cholesterol. One heterozygous enzyme defect (cystathionine-p synthase) in the homocysteine pathway is also common in the general population. There is now a mounting case for initiating randomised controlled trials of folate supplementation to help to unravel the interaction of gene, diet, and environment. K D Hopkins
Vol348 *August 17, 1996
Biomarkers from and NASA budgets for Mars
T
he evidence behind recent “Life on Mars” headlines appears this week in Science. Ex-life off that planet is a fairer summary. David S McKay and his colleagues - from the US
- 4500 million years - 15 million years - 13 thousand years - 20 years - 14 years - 12 years - 2 years zero (1996) + 1year + 5 years + 9 years
Antarctica where it was found in 1984. It is the largest of 12 martian meteorites found on earth identified as such by the close match between the gases trapped in them and data
__
ALH 84001 matc?rialformed Asteroid hits Mairs. ejecting ALH84001 into space Meteorite lands iin Antarctica Viking Mars landing experiments Recognition of fii’st lunar meteorite ~ ~ ~ 8 4founc 0 01 1 ALH84001 ident ified as probably martian. Mars Observer missioii fails Report of relic biogenic activity, in Science Landings of Mar!j surveys despatched this year ?joint US/Russi a launch ? return of marti;an geological material
explanation too; furthermore, the hydrocarbons were found deep in the specimen. There has been controversy over whether the carbonates can only form in high temperature processes, too high to be compatible with any sort of “life”. However, isotope and other evidence now points to the process occurring at temperatures in the 0-80 “C range. The scientists also looked at the carbonate globules in detail, adding two more threads of evidence to the ‘‘life’’ claim-namely, the presence of iron compounds of possible biogenic origin, and electronmicroscopic features resembling those found in concretions grown from Pleistocene groundwater and “interpreted as representing nanobacteria”. What next? According to an anticipated report from the Committee on Planetary and Lunar Exploration (Nature 1996; 382: 481), NASA’s current budget may not allow for the bringing back to Earth of maman material of the sort that would permit more direct confirmation of the recent claim. If President Clinton’s response to the meteorite’s contents is anything to go by, ALH84001 may do wonders for NASA.
National Aeronautics and Space Administration, having carefully discussed what they found in an Antarctic meteorite supposedly of martian origin, say that they have evidence for “primitive life on early Mars”(Science 1996;273: 924-30). The Viking probes had recorded no evidence of organic material in martian surface “soil” and no evidence for fossils either. McKay et a1 have been looking at something much closer to home, a meteorite known as ALH84001, after the Allan Hills in
recorded by the Viking experiments. -84001 is rich in carbonates, unlike other meteorites of this class, and it was in regions of the meteorite high in carbonates that simple polycyclic hydrocarbons were found (eg. phenanthrene, pyrene, chrysene, and anthracene), the first evidence for organic molecules in martian rock. But could this be terrestrial contamination? McKay and colleagues are confident about their handling of the material. Industrial contamination in the Antarctic is an improbable
Bigger babies booming
Coronary artery disease: the folate link
T .
I.
he growth charts used by most Amencan physicians to monitor child progress are outdated and need revision, says a paper in Arch Pedian Adolesc Med (1996;150: 842-49) Helen Binns (Children’s Memorial Hospital, Chicago, USA) and colleagues from the area Pediatric Practice Research Group studied 1574 healthy term infants born in Chicago in the mid 1980s, and compared their growth with standard growth curves provided by the National Center for Health Statistics, based on data collected from a sample of 867 infants born between 1929 and 1975. The average PPRG baby weighed about 3.4 kg at birth-about 0.2 kg more for girls and about 0.13 kg more for boys than the NCHS norm. “Because the PPRG curves are shifted up, use of the NCHS curves to plot the weight of PPRG infants would result in under identification of underweight infants and over identification of overweight infants”, write the authors. 0
464
ncreased homocysteine concentrauons have gained recent attention as a potentially modifiable risk factor for coronary heart disease (CAD). Several calls have now been made for randomised controlled trials of folate supplements to lower plasma homocysteine levels (see Lancer, June 29, ~1823).But a Hong Kong study on southern Chinese, a population with an increasing prevalence of CAD, is a reminder that studies seeking to define the role of diet must also pay close attention to other risk factors. In this study (Heart 1996; 76: 1 17-22), significantly increased postmethionine-loading test homocysteinaemia (hyperHcy) was found in patients with angiographically proven CAD compared with healthy volunteers. People with hyperHcy had significantly higher folate concentrations than normoHcy individuals. Other studies have found significant negative correlations between hyperHcy and folate-suggesting a role for folate supplements.
David Sham
In the Hong Kong study, 16 of 17 patients with CAD and hyperHcy smoked compared with only 9 of 28 CAD patients with normal methionine-loading tests. Smoking, however, rather than hyperHcy was the only independent risk factor for CAD on multivariate analysis, say the authors. It is well established that severe hyperHcy is associated with premature vascular disease although the mechanism by which altered homocysteine metabolism causes vascular damage is uncertain. Other factors affect homocysteine such as sex, smoking, blood pressure, and cholesterol. One heterozygous enzyme defect (cystathionine-p synthase) in the homocysteine pathway is also common in the general population. There is now a mounting case for initiating randomised controlled trials of folate supplementation to help to unravel the interaction of gene, diet, and environment. K D Hopkins
Vol348 *August 17, 1996