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Results for “TROPICAL CLIMATE”

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At least 127 records · Page 7Linked to original sources
PubMed1986

The influence of season and shade on oestrous behaviour, timing of preovulatory LH surge and the pattern of progesterone secretion in FFPN and Creole heifers in a tropical climate.

The aim of this work was to study the duration of oestrous behaviour, timing of the LH surge and the progesterone pattern with and without shelter during January and again in July in FFPN and Creole heifers in a tropical environment. From days 21 to 28 after a synchronization treatment (progesterone + PMSG), ten Creole heifers and ten FFPN heifers were checked for oestrus and sampled for blood every 3 h to assay plasma LH levels and every day from that oestrus to the following one to assay plasma progesterone content. Five heifers in each group were housed in a covered corral and five were exposed to the sun in a corral without shelter. The mean duration of oestrus for all the heifers was 14.0 h. There was a significant breed/season interaction: 21 h in July and 15 h in January for FFPN heifers. Sun exposure did not significantly affect the mean duration of oestrus. The distribution of onset of heat with respect to time of day was not uniform: 29% of the oestruses began between 5 and 8 a.m. and 19% between 8 and 11 p.m. The mean interval between onset of heat and maximal LH value (3.58 h) only varied significantly with the season (1.6 h in January and 6.0 h in July; P less than 0.05) but was equivalent to those obtained by other authors. The plasma progesterone levels of both breeds were lower than those described for cows in temperate countries and were lower for shaded FFPN heifers in January (2.8 ng/ml) than in July (3.93 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Adverse skin reactions to transdermal oestradiol in tropical climate. A comparative study of skin tolerance after using oestradiol patch and gel in Thai postmenopausal women.

A crossover randomized comparison between two different transdermal oestradiol delivery systems has been performed in post-menopausal women of the Bangkok area. Clinical benefits were identical with the use of either a gel, applied once/day on 800 cm2 of skin and which totally evaporated within 3 min, or a patch applied for 3-5 days on 20 cm2 of skin. There was no evidence of pharmacokinetic advantage with the patch, and the day to day intra-individual variations were even greater with patch than with gel. There were no cutaneous side effects with the gel, but unacceptable skin reactions, including itching, vesicular rash and residual pigmentation, were present in 58% of patients during patch use. Therefore a combination, in a small skin area, of adhesive, occlusive effect and high oestradiol concentration does not appear appropriate in hot and humid climate.

Administration, Cutaneous↗
PubMed1998

Plasma concentrations of thyroid hormones in growing pullets and laying hens reared under two tropical climates and fed on diets with different energy concentrations.

1. Blood samples were taken from growing (14-week-old) and laying (36-week-old) hens reared in either a temperate or a hot, humid climate and fed on 2 dietary energy concentrations (10.03 or 11.7 MJ ME/kg) to determine the plasma concentrations of 3,3',5'-triiodothyronine (T3) and thyroxine (T4) by radioimmunoassay. 2. Plasma T3 concentrations were higher in birds fed on the low energy diet and higher at 14 than at 36 weeks of age, while the effects of climate were complex. 3. Plasma T4 concentrations were higher at 14 than at 36 weeks of age and interactions with the dietary and climatic factors were observed. 4. Interactions between dietary and climatic factors were observed since plasma T3 and T4 concentrations were higher at 14 weeks under the hot, humid than under the temperate climate. Furthermore, at 36 weeks plasma T3 concentrations were higher under the temperate climate and plasma T4 concentrations did not differ. 5. These findings are not easy to explain. However it may be suggested that the energy content of the diet clearly affects the plasma concentrations of thyroid hormones and that this effect is modulated by the climate to a variable degree that is linked to the age and the physiological state of the birds.

Aging↗
PubMed1987

Variability in the composition of human skin surface lipids in tropical climates.

Skin surface lipid samples were collected by the hexane sponge technique from the foreheads of 180 male and 131 female Saudi subjects living in the Jeddah-Makkah area (summer temperatures up to 47 degrees C). The lipid samples were analyzed by densitometric thin layer chromatography. Seven major lipid classes were determined. The percentages for squalene, cholesterol esters, wax esters, triglycerides, free fatty acids, cholesterol and diglycerides were determined. When these parameters were compared to the corresponding values reported for subjects living in the much cooler climates of Europe and N. America, most of the values for Saudi females were found very similar to the values of these subjects, while for Saudi males squalene and wax esters were 2.8-5.1% higher and the triglycerides/free fatty acids were 3-5% lower. The possible reasons for the observed variability between both sexes, their relation to European and N. American subjects, as well as the role of hot climates in inducing these variations are discussed.

Adolescent↗
PubMed2001

Tropical climate changes at millennial and orbital timescales on the Bolivian Altiplano.

Tropical South America is one of the three main centres of the global, zonal overturning circulation of the equatorial atmosphere (generally termed the 'Walker' circulation). Although this area plays a key role in global climate cycles, little is known about South American climate history. Here we describe sediment cores and down-hole logging results of deep drilling in the Salar de Uyuni, on the Bolivian Altiplano, located in the tropical Andes. We demonstrate that during the past 50,000 years the Altiplano underwent important changes in effective moisture at both orbital (20,000-year) and millennial timescales. Long-duration wet periods, such as the Last Glacial Maximum--marked in the drill core by continuous deposition of lacustrine sediments--appear to have occurred in phase with summer insolation maxima produced by the Earth's precessional cycle. Short-duration, millennial events correlate well with North Atlantic cold events, including Heinrich events 1 and 2, as well as the Younger Dryas episode. At both millennial and orbital timescales, cold sea surface temperatures in the high-latitude North Atlantic were coeval with wet conditions in tropical South America, suggesting a common forcing.

Journal Article↗