Nocturnal Concentrations Research Articles

Pulsatile secretion of luteinizing hormone in children.

The gonadotropin secretory patterns of 22 sexually immature children were analyzed in detail to determine whether pulsatile secretion occurs before the onset of puberty. Eight endocrinologically normal children, 13 children with isolated GH deficiency, and 1 girl with 45X gonadal dysgenesis were divided into 2 groups according to bone age. Group A children had bone ages less than 10 yr, and group B had bone ages between 10-11.5 yr. Blood samples were drawn every 20 min for periods of 3-11 h during both the day and night; in addition, 12-h urine collections were made for gonadotropin determinations. Mean nocturnal concentrations of LH and FSH were significantly greater than daytime values in 8 of 15 and 5 of 15 children in group A and in 6 of 7 and 1 of 7 in group B, respectively. Nocturnal urinary excretion of LH and FSH was significantly greater in group A children. Eight children in group A, including 4 whose bone ages were less than 5 yr, and 4 group B children had discernible LH pulses. LH pulses were detected during the day and night in both groups. LH pulse amplitude was greater during the night in both groups, but was greatest in group B (A, 1.9 +/- 0.2 mIU/ml; B, 3.0 +/- 0.3 mIU/ml). In children who demonstrated pulsatile secretion, LH pulse frequency appeared to be similar during the day and night and was slightly faster in the older children (A, every 3 h; B, every 2 h). These studies demonstrated that LH is secreted in a pulsatile manner well before the onset of puberty. Furthermore, the gonadotropin secretory pattern characteristic of early puberty results from the amplification of an already existing circadian pattern of gonadotropin secretion.

Background environmental pollution of the Eurasian continent

(1) The interest to studying pollution of environmental media on the background level has grown in the recent years. There arose a necessity to establish a specialized observational system for conducting observations of changes in the state of the environment, and of ecological consequences of pollution as well as to produce assessments of the current and predicted states. The realized program of background monitoring and first results of integrated background measurements have already been published. The paper presented illustrates time-and-space features of the background pollution of natural environmental media according to data from various background stations. (2) Long-term systematic measurements at the 'Borovoe' station (Kazakh SSR) commenced in 1976 have been supplemented with the results of the background pollution studies carried out in Berezinskyi, Caucasian, Central-Chernozem, Sary-Chelek, and Repetek Biosphere Reserves and in locations of the background stations in Hungary and Czechoslovakia. The data from the Hungarian and Czechoslovak stations were obtained during joint expeditions. Details are given in the relevant publications. (3) Ozone. Ozone measurements show the diurnal variation with the day-time maxima from 35 up to 160 μg m(-3). The correlation between day-time and nocturnal concentrations is a good indicator of the anthropogenic effect. (4) Sulphur dioxide and sulphates. The annual variation of sulphur dioxide characterised by winter maximum and summer minimum indicates the direct dependence on the amount of fuel burnt in the given region. Mean values of the sulphur dioxide content in the surface layer of the atmosphere correlates with the extent of the region urbanization and varies within 0.2-12.5 μg m(-3). The value of sulphur dioxide and sulphates correlation in the atmosphere is rather stable and varies within 0.18-0.37 μg m(-3). (5) Heavy metals. The annual cycle of the atmospheric content of lead, cadmium and arsenic is well expressed by winter maximum and summer minimum (which is opposite in case of mercury). As for lead and mercury, their annual variation is more distinct than that of cadmium and arsenic; their time-and-space variation is also more distinct. The content of these metals in the urbanized regions of Europe is 5 times higher than in Asia and the Caucasus. Atmospheric contents of arsenic and cadmium vary insignificantly from region to region. The content of all these metals in other environmental media (soil, water, vegetation) is of insignificant spatial variability. Observations in the Caucasian Biosphere Reserve showed minimum levels of the background atmospheric pollution: lead-16 μg m(-3), mercury-5 ng m(-3), arsenic-3.9 ng m(-3), cadmium-0.5 ng m(-3). (6) Organochloride pesticides. Concentrations of DDT and its metabolites and hexachlorocyclohexane isomers in the environmental media of European background regions are 3 times higher than those in Asia ('Borovoe'). (7) PAH. Atmospheric content of BaP has a well expressed annual variation with winter maximum; the difference between winter and summer periods reaches the magnitude of an order. Background concentrations in European regions (Hungary, Berzinskyi Biosphere Reserve) are noticeably higher than in Asia; the difference reaches 3-5 times. (8) Comparisons with literature data on the background pollution show that observational materials from the background monitoring stations supplement to a considerable extent, and extent, the current notions on the background pollution and show the effects of the man-made impact on the background regions.

Overnight Plasma Profiles of Melatonin and Certain Adenohypophyseal Hormones in Men*

Melatonin levels exhibited a day-night rhythm with highest levels at night. Nocturnal plasma melatonin concentrations were unrelated to sleep stages, whereas secretion of GH was temporally related to slow wave sleep. Levels of corticotropin rose in the later sleep cycles. We found no relationship between endogenous nocturnal melatonin and adenohypophyseal hormone levels. The results indicate that in young men nocturnal levels of melatonin are controlled separately from those of LH, PRL, corticotropin, and GH.

Shelter-effects on microclimate, growth and water use by irrigated sugar beets in the great plains

Two rows of corn windbreaks spaced at 15 m were used to protect an irrigated sugar beet crop at Scottsbluff, Nebraska. Yield data for wind protected sugar beet crops from three consecutive years indicate that yield increases of as much as 25% are possible during years when yields are low. During years of high yield, however, the windbreaks did not increase sugar beet yield further. Except in the immediate vicinity of the windbreak where shading occurred, no differences were found in net radiation between the sheltered and open plots. The daytime air temperature averaged 1.8°C greater and the vapor pressure 4.0 mbar greater in the sheltered plot than in the open. Both air temperature and the water vapor pressure varied as a function of distance from the windbreaks. An area of maximum influence was often observed near the center of the protected plot. Differences between shelter and open were decreased during periods of strong wind. Differences in temperature and vapor pressure between shelter and open were greater during the day than at night. The wind speed at 25 cm above the crop was 40% of that in the open field whenever wind speed in the open was more than 120 cm/sec. The daytime concentration of CO 2 was an average of 1 p.p.m. lower in shelter than in the open. Nocturnal concentration was an average of 3.5 p.p.m. greater in shelter. The latter differences were inversely related to wind speed and were greatest when wind direction was perpendicular to the windbreak. Vertical mixing in the atmosphere is, apparently, vigorous enough to prevent significant depletion of CO 2 in a windbreak protected field. The 1 p.p.m. lower concentration observed over the sheltered crop should have only a negligible influence on photosynthetic rate. The increase in vapor pressure and the slight decrease in [CO 2] during the day suggest a decrease in the intensity of turbulent exchange in shelter. The concentration of water vapor exceeds that of CO 2 by several orders of magnitude. Decreased turbulent exchange in shelter has, therefore, a far greater influence on the change in concentration of water vapor than of CO 2.

THE ROLE OF ZOOPLANKTON IN THE NUTRITION OF SOME SCLERACTINIAN CORALS1

Over 15 days of continuous monitoring, the mean nocturnal concentration of drifting net zooplankton in a coral reef community on the Bermuda platform was 0.83 mg m−3. The mean respiration rate of reef‐building corals at the study site was calculated to be 6.4 g O2 day−1 m−2 of reef bottom. Using these data we show that the energy requirement of these corals was more than an order of magnitude greater than the energy they could obtain by capturing the sparse zooplankton in the surrounding waters.The question follows, why, if corals can exist in the absence of energetically significant quantities of zooplankton, do their elaborate anatomic modifications for catching zooplankton persist? Evidence indicates that corals cannot obtain their phosphorus requirements from solution. We therefore suggest that relatively small amounts of zooplankton may be important as a source of phosphorus and perhaps of other essential nutrients for both the coral and its algal symbionts.

CONCENTRATION OF CO2IN THE AIR ABOVE A SUGAR BEET FIELD*

The concentration of CO, in air sampled above a sugar beet crop was measured during July, August, and early September 1966 at Scottsbluff, Nebr. During July the mean daytime concentration decreased from 310 ppm to 283 ppm as the leaf area index increased from 0.8 to 4.0. Only small deviations from the mean daytime Concentration of 283 ppm occurred during the remainder of the season. The mean nocturnal concentration during this period was 320 ppm and was more variable than the daytime concentration. The daily amplitude of concentration averaged 70 ppm and was as great at times as 100 ppm. Regression analysis revealed strong negative correlation between COZ concentration and mean wind speed during the night. Mean concentration was independent of mean temperature, mean incident radiation, and predominant wind direction. During each day the concentration remained constant between 1% hr after sunrise and 1 hr before sunset except for a few cases. These were associated with incident radiation below 0.2 cal cm-2 min-1 and/or wind speeds at 25 cm above the crop of less than 0.3 m sec-l or more than 3 m sec-I. Evidence is presented that the concentrations reported here are at least partially dependent on the flux to and from the sugar beet crop.