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Results for “TROPICAL CLIMATE”

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At least 199 records · Page 11Linked to original sources
PubMed2002

Exercise-induced asthma among Thai asthmatic children.

BACKGROUND: Approximately seventy per cent of asthmatic children from temperate climates, with normal lung function, have exercise-induced asthma (EIA). There is certain evidence to suggest that EIA may be less frequently encountered among children who live in tropical climates. Prevalence of EIA in Asian asthmatic children has never been thoroughly studied. OBJECTIVE: To study the prevalence of EIA among Thai asthmatic children. METHOD: A prospective study was performed to determine the prevalence of EIA in 44 Thai asthmatic children who were able to perform the spirometric maneuver. Subjects were randomly selected asthmatic children from the Pediatric Allergy Clinic, Department of Pediatrics, Siriraj Hospital. They were subjected to exercise testing on a steady state, motor-driven treadmill for 6 minutes (mean speed +/- SD = 3.7 +/- 0.4 km/h, mean level of inclination + SD = 15.0 +/- 5.2 degrees). The testing was conducted in a temperature-controlled (mean temperature +/- SD = 24.4 +/- 0.8 degrees C) and humidity-controlled environment (mean relative humidity +/- SD = 41.7 +/- 2.1%). Lung function tests were performed before exercise, immediately after and at 3, 5, 10, 15, 20 and 30 minutes after exercise. Results of the lung function test were calculated as per cent falls of forced expiratory volume in 1 sec (FEV1), peak expiratory flow rate (PEFR), and forced expiratory flow at 25 per cent-75 per cent (FEF50) from baselines. EIAs were diagnosed when drops of FEV1, PEFR and FEF50 were greater than 20 per cent, 25 per cent and 25 per cent from baseline values, respectively. RESULTS: Of the 44 patients studied (31 boys and 13 girls; mean age 11.9 years), 34 per cent had mild asthma. Fifty-nine per cent had moderate asthma and 7 per cent had severe asthma. Eleven patients (25%) had EIA diagnosed by significant falls of FEV1's (26 +/- 12.6%), whereas, 13 patients (30%) and 20 patients (45%) had EIA defined by significant drops of PEFR's and FEF50's, respectively. A total of 23 patients (52%) had EIA by one or more diagnostic criteria. Peak times for EIA as diagnosed by FEV1, PEFR and FEF50 occurred at 3, 10, and 10 minutes respectively, after exercise. Most EIA episodes observed were of mild degree. CONCLUSIONS: The prevalence of EIA in Thai children is much lower than figures reported in studies from Western countries. By using a significant fall of FEV1's as the diagnostic criteria, only 25 per cent were diagnosed as having EIA. By PEFR and FEF50 criteria, percentages of EIA increased to 30 per cent and 45 per cent respectively. Screening for EIA, therefore, may not be an appropriate diagnostic tool for the diagnosis of childhood asthma in tropical climates.

Adolescent↗
PubMed2006

Cenozoic plant diversity in the neotropics.

Several mechanisms have been proposed to explain the high levels of plant diversity in the Neotropics today, but little is known about diversification patterns of Neotropical floras through geological time. Here, we present the longest time series compiled for palynological plant diversity of the Neotropics (15 stratigraphic sections, 1530 samples, 1411 morphospecies, and 287,736 occurrences) from the Paleocene to the early Miocene (65 to 20 million years ago) in central Colombia and western Venezuela. The record shows a low-diversity Paleocene flora, a significantly more diverse early to middle Eocene flora exceeding Holocene levels, and a decline in diversity at the end of the Eocene and early Oligocene. A good correlation between diversity fluctuations and changes in global temperature was found, suggesting that tropical climate change may be directly driving the observed diversity pattern. Alternatively, the good correspondence may result from the control that climate exerts on the area available for tropical plants to grow.

Biodiversity↗
PubMed2004

An historical perspective on early progress of Queensland water fluoridation 1945-1954: sheep, climate and sugar.

BACKGROUND: Queensland's virtual rejection of artificial water fluoridation sets it apart from other Australian states, yet the early fluoride environs has been scantily recorded. METHODS: This paper used archives, literature review, personal interview and the traditional historic method. RESULTS: The connection between Queensland artesian bore water and caries resistance was postulated as early as 1912. Four decades later, two Queensland-specific factors influenced the planning to fluoridate community water supplies. The first (1945-1950) was confusion between the high levels of fluoride in artesian water supplying the pastoral industry and the scientific concept of artificial water fluoridation of communal supplies. The second (1952-1954) involved further scientific investigation involving water consumption patterns, occupational dehydration and fluid homeostasis within a sub-tropical climate. The role of the Australian Dental Association Queensland Branch (ADAQ) in early fluoride politics was minimal. Four early protagonists are identified--two dentists, an engineer and the sugar industry. CONCLUSIONS: Queensland had its advocates for artificial water fluoridation of communal supply as a means of caries prevention. Interest came from the dental, medical and engineering professions, and from the sugar industry. However, these efforts met with indifference based on confused extrapolation of the artesian experience (1945-1952) and hesitancy (1952-1954) due to contemporaneous concerns about human fluid homeostasis in Queensland's sub-tropical climate.

Animal Husbandry↗
PubMed1977

Comparison of physical characteristics, body temperature and basal metabolism between Thai and Japanese in a neutral temperature zone.

The aim of this research is to compare the physical status, basal metabolism and some other physiological characteristics between native Thai in Bangkok, Thailand, and native Japanese in Japan, and discuss the results regarding acclimatization to tropical climate. Measurements of the Thai were made in September in Bangkok, while those of native Japanese were done in August at Nishinomiya (Japan). The subjects were adult males (20-22 years old) in both cases. Physically the Thai are generally a little shorter and more slender than Japanese in the mean value. The mean skinfold thickness for Thai was 8.4 mm, which is significantly less than that of Japanese (11.0 mm). The mean oral temperature measured under basal conditions was the same between both subject groups. The Thai showed a slightly lower basal metabolism per unit body surface, and mean skin temperature measured in a similar environmental condition was lower for Thai than for Japanese. The results of anthropometric measurements and physiological characteristics measured were discussed in view of physiology of acclimatization ot tropical climate.

Acclimatization↗
PubMed2006

Air pollution and postneonatal mortality in a tropical city: Kaohsiung, Taiwan.

With growing evidence of the association between daily mortality and air pollution in adults, it is important to investigate whether infants are also susceptible to the adverse health effects of ambient air pollutants. The purpose of this study is to examine the relationship between air pollution and postneonatal mortality in Kaohsiung, Taiwan, a large industrial city with a tropical climate, during the period 1994-2000, using a case-crossover analysis. Case-crossover analysis provides an alternative to Poisson time-series regression for studying the short-term adverse health effects of air pollution. The air pollutants examined included particulate matter (PM(10)), sulfur dioxide (SO(2)), ozone (O(3)), nitrogen dioxide (NO(2)), and carbon monoxide (CO). The risk of postneonatal deaths was estimated to increase by 4.0% per 67 microg/m(3) (the interquartile range in daily ambient concentration of PM(10)) for PM(10), 1.8% per 17.84 ppb for NO(2), 5.1% per 0.31 ppm for CO, and 4.6% per 19.20 ppb for O(3). Although positive, none of these associations achieved statistical significance. The established link between air pollution levels and infant mortality may not be as strong in cities with tropical climates, although other factors such as differences in pollutant mix or the underlying health of the postneonates may explain the lack of a strong association in this study. Further studies of this type in cities with varying climates and cultures are needed.

Air Pollution↗
PubMed1982

Seasonal variation in seminal and testicular characteristics of Brazilian Somali rams in the hot semi-arid climate of tropical northeast Brazil.

The seasons in the 1 year study were classified as rainy, transitional rainy-dry, dry, and transitional dry-rainy. Semen pH and the consistency of the testes did not vary between seasons or among rams. All other characteristics of semen and testis varied between rams. Significant seasonal differences were observed for ejaculate volume, mass, % motility, forward motility score and concentration of spermatozoa, and linear testis measurements. The total number of spermatozoa per ejaculate did not vary seasonally. The magnitude of the seasonal effects was not sufficient to prevent the rams being used for breeding throughout the year.

Animals↗
PubMed1983

Total serum IgE levels in Venezuelan schoolchildren.

Seventy-eight disease-free children were evaluated by PRIST for total serum IgE in order to establish the normal range for this immunoglobulin and assess its utility, in tropical climates, such as Venezuela, as a diagnostic tool for clinical allergy. Seventy-eight normals were selected from a group of 1053 children, aged 7-12 years from fourteen schools in Caracas. Exclusion from the normal pool was based on nationality, and on historical, clinical, and/or laboratory evidence of atopic and/or infectious diseases, particularly with parasites. In addition to a routine CBC and differential, the following studies were performed: a search for stool ova and parasites; in vitro (RAST) and in vivo (skin prick) testing for specific IgE to Dermatophagoides pteronyssinus, Aspergillus fumigatus, and ragweed. Measurement of antibodies against influenza A and B, adenovirus A2 and B, cytomegalovirus, parainfluenza 1 and 3, herpes simplex, respiratory syncytial virus, Coxsackie B1 to B6, Mycoplasma pneumoniae and Rotavirus was also carried out. Normal serum IgE levels for disease-free children in the age group studied ranged from 1.7-255 mu/ml. The highest average level (Y: 74 mu/ml) occurred at the age of 9 years. These values differed significantly from age-matched control groups of known atopic and helminth-infected children. Thus, once common causes for elevated IgE levels are eliminated, determination of total serum IgE can be utilized as a valuable tool in diagnosis of clinical allergy in countries with tropical climates.

Aging↗
PubMed1994

Correlation between meteorological conditions and mutagenicity of airborne particulate samples in a tropical monsoon climate area from Kaohsiung City, Taiwan.

Kaohsiung is a city of 1.5 million located in the southern part of Taiwan. It has a serious air pollution problem mainly attributable to much industrial and commercial activity. In order to estimate the effects of traffic, season, and meteorological conditions on the mutagenicity of Kaohsiung City's urban ambient particulate matter, 624 airborne particulate samples were collected on a weekly basis from 12 locations for an entire year. The mutagenic potential of acetone extracts of air samples was evaluated by the Salmonella/microsomal test with S. typhimurium TA98 in the presence and absence of S9 mixtures. The air samples from November 1990 showed the highest direct and indirect mutagenicity among the 12 months, whereas those from June and July 1991 had the lowest direct and indirect mutagenic activity, respectively. The mutagenicity showed a good correlation with amounts of the acetone extractable matter of airborne particulates. The meteorological conditions, monthly mean precipitation, and wind speed also showed a good correspondence with mutagenicity. Wind direction and temperature had a moderate relationship. The major mutagenic fractions of air samples that had the highest mutagenic activity in a month were purified using Sephadex LH-20 column chromatography, and the contents of PAHs, 1-NP, and DNPs were analyzed by HPLC. The characteristic concentration ratios of PAHs indicated that, for the main pollution sources of airborne particulates from Kaohsiung city, the mobile sources were more important than the stationary ones. The total amounts of 1-NP and DNPs in airborne particulates seemed to correspond to their mutagenicity. Although the total amounts of 1-NP and DNPs in the air samples correlated with their mutagenicity, the major mutagenic chemicals in the airborne particulate samples from Kaohsiung City need further investigation.

Air Pollutants↗
PubMed2006

The effect of 8 days of training in tropical environment on performance in neutral climate in swimmers.

The tropical climate imposes a high level of physiological stress during exercise. As a result of this stress, adaptations may be induced and could benefit athletes upon return to a neutral climate. To test this hypothesis, climate effects on swimming performance were assessed in 16 swimmers: 6 trained for 8 days in a tropical climate, 6 trained for 8 days at altitude, and 4 served as a tapering group. The swimming performance was assessed during a 400-m freestyle before the experimental period, and at 10 days and 30 days after. The results demonstrated that only the tropical group increased performance (10.0 +/- 4.2 %, p < 0.03 for the tropical group 30 days after return). No significant change in performance was noted for the two other groups 10 or 30 days post-training. The results of the present study demonstrated that training in a tropical climate significantly enhances performance in swimmers 30 days after return to neutral climate. However, further studies are needed to evaluate the effects of such a climate on performance in other sports.

Adolescent↗
PubMed2000

Does the failure to acquire helminthic parasites predispose to Crohn's disease?

Two polarized patterns (Th1 and Th2) of cytokines regulate inflammatory responses. Each cytokine pattern inhibits production of the opposing pattern. Lymphocytes from inflamed intestine due to Crohn's disease secrete a Th1 pattern of cytokines. Crohn's disease is most prevalent in highly industrialized countries with temperate climates. It occurs rarely in tropical third world countries with poor sanitation. We propose that exposure to an environmental agent predisposes individuals to Crohn's disease. Parasitic worms (helminths) are common in tropical climates and in populations subject to crowding and poor sanitation. Children are most subject to helminthic colonization. Many helminths live within or migrate through the human gut where they interact with the mucosal immune system. The host mounts a mucosal response that includes Th2 cytokine production limiting helminthic colonization. Helminths and their eggs probably are the most potent stimulators of mucosal Th2 responses. The Th2 response provoked by parasitic worms can modulate immune reactions to unrelated parasitic, bacterial, and viral infections. Many people in developed countries now live in increasingly hygienic environments, avoiding exposure to helminths. Perhaps failure to acquire these parasites and experience mucosal Th2 conditioning predisposes to Crohn's disease, which is an overly active Th1 inflammation.

Animals↗
PubMed2004

The causes and diagnosis of influenza-like illness.

BACKGROUND: Influenza and other respiratory viruses circulate between spring and autumn in temperate climates and all year in tropical climates. These viruses cause symptoms often referred to as influenza-like illness (ILI), but are not generally distinguishable on clinical grounds alone. OBJECTIVE: This article provides a brief review of the surveillance, viral causes and current diagnostic methods used to identify viruses causing ILI. DISCUSSION: Influenza-like illness surveillance with laboratory support, conducted in most Australian stats and territories, aims to define the impact of influenza seasons in the community and provide virus strains that may be used in future vaccine formulations. Surveillance may also be useful in the early stages of an influenza pandemic. In addition to influenza, viruses known to cause ILI include respiratory syncytial virus, rhinovirus, adenovirus, parainfluenza viruses, human coronaviruses (including the virus that causes severe acute respiratory syndrome) and the recently recognised human metapneumovirus. Polymerase chain reaction assays are the most common diagnostic tests now used for the differential diagnosis of ILI.

Australia↗