SYNOPSIS Serum uric acid estimations were performed in 106 healthy pregnant women during early, middle, and late pregnancy, using an automated colorimetric method. The mean serum uric acid level was significantly lower during early and middle pregnancy than that of 64 age-matched female controls. The serum uric acid level was not significantly different in late pregnancy from the control group. Studies of the daily urinary urate excretion in 31 pregnant women showed normal urinary urate excretion in early pregnancy and enhanced renal loss of urate in middle and late pregnancy. It appears that the renal clearance of urate in pregnancy is high, especially in the middle period when the serum level is low in spite of the increased production of uric acid by the foetus.Pregnancy has a favourable influence on the symptoms of gout (Lee and Loeffler, 1962), and, although gout is uncommon in premenopausal women, exacerbations have occurred in the puerperium (Greenhut, Silver, and Campbell, 1953). Weingold (1960) reported a patient with gout who remained symptom-free during her pregnancy but had an acute attack of gout 18 hours after delivery.These observations prompted interest in the influence of pregnancy on the serum uric acid level. The vast majority of the very numerous studies of serum uric acid levels in pregnant women have been concerned with the rise which occurs in preeclampsia. Only one study to our knowledge deals with the serum uric acid level in normal pregnancy (Steenstrup, 1963) where low values were encountered. We felt that it would be of value to confirm this work and to investigate the cause of the hypo-uricaemia. MATERIALS AND METHODSOne hundred and six pregnant women were studied. The mean age was 25-8 years (range 17 to 49 years). Forty-four patients were in early pregnancy (0 to 16 weeks), 48 were in middle pregnancy (17 to 28 weeks), and 14 were in late pregnancy (over 28 weeks). These women were all Received for publication 7 February 1966. attending an antenatal clinic. No patients in this study had essential hypertension, chronic nephritis or preeclampsia; none were receiving salicylates at the time of study, none had a raised blood pressure (140/90 mm. of mercury or more) or demonstrated albuminuria. Mild ankle oedema was not taken as a contraindication to inclusion in the study unless it was associated with signs of pre-eclampsia. All patients studied were healthy in other respects.The control sample consisted of 64 healthy nonpregnant women who had been seen in the course of a twin study and who had been drawn from the general population by advertisement in the press The mean age of the sample was 19-3 years and the range 12 to 40 years.Venous blood was taken into a glass container and allowed to clot. Serum samples from all subjects were frozen and stored for at least three weeks before determination of the uric acid concentration, because Buchanan, Isdale, and Rose (1965) have shown that nonurate chromogens which interfere with the colorimetric methods of uric acid estimation disappe...

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Abstract-An effective and robust time synchronization scheme is essential for many wireless sensor network (WSN) applications. Conventional synchronization methods assume the use of highly accurate crystal oscillators (10-100 ppm) for synchronization, only correcting for small errors. This paper suggests a novel method for time synchronization in a multi-hop, fully-distributed WSN using imprecise CMOS oscillators (up to 15,000 ppm). The DiStiNCT technique is power-efficient, computationally simple, and robust to packet loss and complex topologies. Effectiveness has been demonstrated in simulations of fully connected, grid and uni-directional ring topologies. The method has been validated in hardware on a grid of nine sensor nodes, synchronizing to within a mean error of 6.6 ms after 40 iterations.

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