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In our increasingly immunocompromised populations, zygomycosis is becoming more common. It occurs in two forms. Mucormycosis is an acute, necrotic, rapidly progressive disease of the immunocompromised patient that may lead quickly to death. Entomophthoromycosis is a chronic, slowly progressive subcutaneous disease seen mostly in immunocompetent patients living in tropical climates.
OBJECTIVE: To evaluate the risk of the practice of spinal anaesthesia (SA) in African tropics. STUDY DESIGN: Prospective study in multiple centres over a two years period. PERSONS: Twenty-one anaesthesiologists and anaesthetist nurses covering ten African countries. METHODS: Two anonymous questionnaires; the first, filled in each anaesthetic problem occurred, to define the type of incident or accident, and its circumstances; the second was designed to define the position occupied, to quantify the global anaesthetic activity, the number of SA, and to value the number of complications or deaths linked to SA. RESULTS: Six anaesthesiologists and one anaesthetist nurse replied to the study, covering six sites in five different countries (Senegal, Chad, Central African Republic, Niger and Madagascar). On the 18,432 anaesthetic acts collected, 2,703 (14.7%) were SA. In the well-equipped centres, general anaesthesia was predominant with a frequency of over 75%. However in the not so well equipped centres or those which supplies were more problematical, SA technique was used with a frequency varying from 48.9 to 68.7%. Forty incidents and accidents were reported (1.5%), five led to the death of the patient (0.2%). Among the seven cardiac arrests (0.3%), four were fatal (0.1%). Eight of the ten accidents and all of the deaths occurred in the least equipped centres. Eight of ten accidents happened during emergency caesarean sections. All cardiac arrests were preceded by a severe hypovolemia. For the four deaths after cardiac arrest, an anaesthetist nurse with isobaric bupivacaine 0.5% carried out SA. CONCLUSIONS: This study showed that the practice of SA in African tropics was performing in different practice conditions and people qualification than they were in France. The frequency of cardiac arrests and deaths was respectively five and 20 times more important, in those conditions. The first conclusion that can be drawn from this study is that it is questionable to use SA for emergency Caesarean section under hypovolemic condition. The second is the necessity for specific training on the local anaesthesia for anaesthetist nurses but also training to choose the anaesthesia best adapted to the surgery, the condition of the patient and the means available.
There is still far too little information available on the rheumatic diseases in Africa. Epidemiological studies are required in order to determine the burden of illness from rheumatic diseases on the African continent as well as to identify local risk factors for certain diseases. Such studies will also serve to enable the development of preventative and rehabilitation strategies. Functional disability has to be assessed in relation to the prevailing sociocultural lifestyle on the continent. Measures of disability that reflect this await development whilst regional diagnostic criteria also need to be worked out. The validity of tests and the stability of test reagents in a tropical climate require analysis. Continuing assessment of rheumatological services is essential to ensure their effectiveness and efficiency in the community and in particular to determine health care priorities and the best forms of therapeutic intervention. This will enable judicious use of limited resources. Community surveys in Africa are fraught with constraints and are difficult to undertake owing to a shortage of manpower and financial resources. For this reason, most studies hitherto have been hospital based. Hospital studies though useful lack applicability to the population as a whole and consequently more emphasis on cross-sectional and longitudinal community studies are required. It is hoped that despite the restraints, these studies will be performed.
BACKGROUND: The epidemiology of fungal keratitis varies geographically, but commonly occurs in warm, tropical climates. To determine the microbial and clinical characteristics of this disease in Singapore, we conducted a 5-year hospital-based retrospective study. METHODS: A retrospective review of culture-positive fungal keratitis at the Singapore National Eye Center and Singapore General Hospital, from January 1991 to December 1995. RESULTS: Twenty-nine consecutive cases of culture-positive fungal keratitis were seen over the study period. The mean age of the cases was 41 years and 23 were males. Amongst the varied occupations, 9 were construction workers. The most common cultured organisms were Fusarium sp. (52%) and Aspergillus flavus (17%). More than half had a history of ocular trauma prior to the development of keratitis, while a quarter had antecedent topical corticosteroid therapy. In contrast, only 2 patients were contact-lens wearers. Despite medical therapy, 10 patients eventually required therapeutic penetrating keratoplasties; of these, 6 were caused by Fusarium species. CONCLUSION: Fusarium is the commonest cultured organism in fungal keratitis in Singapore and is associated with significant ocular morbidity.
People visiting or living in tropical or subtropical regions are exposed to various factors, which can lead to edema. Tourists staying for only a short time in the tropics are exposed to different risks, with other disease patterns, than people living in the tropics or immigrants from tropical regions. The differential diagnosis of edema and swelling is extensive and it can sometimes be difficult to distinguish classical edema with fluid retention in the extravascular interstitial space, from lymphedema or swelling due to other aetiologies. The patients often connect the edema to their stay in the tropics although it may have been pre-existing with no obvious relation to their travels. Already the long trip in the plane can lead to an "economy class syndrome" due to deep venous thrombosis. Contacts with animal or plant toxins, parasites or parasitic larvae can produce peripheral edema. The diagnosis can often only be made by taking a meticulous history, checking for eosinophilia and with the help of serological investigations. Chronic lymphedema or elephantiasis of the limbs is often due to blocked lymph vessels by filarial worms. It has to be distinguished from other forms as e.g. podoconiosis due to blockage by mineral particles in barefoot walking people. The trend to book adventure and trekking holidays at high altitude leads to high altitude peripheral edema or non-freezing cold injuries such as frostbites and trench foot. Edema can be an unwanted side effect of a range of drugs e.g. nifedipine, which is used to prevent and treat high altitude pulmonary edema. Protein malnutrition, (Kwashiorkor), and vitamin B6 deficiency, (Beri-Beri) are very rarely observed in immigrants and almost never in tourists. A very painful swelling of fingers and hands in children and young adults of African origin can be observed during a sickle cell crisis. Many protein loosing nephropathies connected with plant and animal toxins but also bacterial, viral or parasitic agents, can lead to edema. But very often edema in tourists or immigrants from the tropics is not related to their stay abroad. To take an accurate history of the itinerary, eating habits and exposure to water etc. is very important. Knowledge of the precise epidemiology and geographic distribution of diseases are essential.
Seasonal breeding is common in mammals, particularly in habitats outside the tropics. Climate and availability of food are the ultimate factors that usually dictate the optimal time of year for a mammal to breed; however, day length (photoperiod) often serves as the proximal cue to signal the onset or cessation of seasonal reproduction. Some individuals in some populations of deer mice are reproductively responsive to photoperiod, while other individuals in the same population are not. As shown here, selection can dramatically alter the frequency of photoresponsiveness in a laboratory population in only two generations. To our knowledge this is the first demonstration of selection for reproductive photoresponsiveness in any mammal. By implication, some wild populations of deer mice must use multiple, genetic-based reproductive strategies, and the degree to which each such strategy is exhibited must be subject to rapid change in response to both seasonally and momentarily changing climatic and dietary conditions.
Industrial activities have driven stratospheric ozone depletion, increasing surface UV-B radiation while exacerbating global warming. These changes limit crop productivity, alter species distributions, and disrupt plant metabolic processes, but the mechanisms linking energy signaling to heat-stress responses remain unclear. Here, we identify the photoreceptor UV RESISTANCE LOCUS 8b (OsUVR8b) as a substrate of SNF1-related protein kinase 1 (SnRK1) in rice and reveal a natural variation at its SnRK1-mediated phosphorylation site (Ser177) that is correlated with adaptation to tropical climates. The thermotolerant OsUVR8bAla177 accessions show geographic enrichment in low-latitude regions with elevated temperatures. Functional validation through prime editing demonstrated that a Ser177-to-Ala177 substitution enhances heat tolerance, whereas the reverse edit compromises it. Mechanistically, OsUVR8bSer177 exhibits reduced stability and an impaired capacity for scavenging reactive oxygen species under heat stress. The regulatory function of the OsUVR8b Ser177 phosphorylation site, a molecular switch that governs UVR8 stability and thermotolerance, can be functionally re-established across rice, Arabidopsis, tobacco, and soybean, indicating its preservation during domestication. Notably, OsUVR8bSer177 maintains higher fertility and yield under non-stress conditions, indicating a tradeoff between heat adaptation and productivity. Our findings thus establish this switch as a key regulator of the yield-resilience balance and a promising target for breeding of climate-resilient crops.
Three ranges of increasing temperatures (35-43, 37-45, 39-47 degrees C) were sequentially applied to a five-stage system continuously operated with cell recycling so that differences of 2 degrees C (between one reactor to the next) and 8 degrees C (between the first reactor at the highest temperature and the fifth at the lowest temperature) were kept among the reactors for each temperature range. The entire system was fed through the first reactor. The lowest values of biomass and viability were obtained for reactor R(3) located in the middle of the system. The highest yield of biomass was obtained in the effluent when the system was operated at 35-43 degrees C. This nonconventional system was set up to simulate the local fluctuations in temperature and nutrient concentrations that occur in different regions of the medium in an industrial bioreactor for fuel ethanol production mainly in tropical climates. Minimized cell death and continuous sugar utilization were observed at temperatures normally considered too high for Saccharomyces cerevisiae fermentations.
This community study on headache in Malaysia was based on IHS diagnostic criteria and showed the last-year prevalence of migraine was 9.0%. Migraine with aura accounted for only 10.6% of the migrainous population. The last-year prevalence of tension headache was 26.5% (94.4% episodic, 5.6% chronic) and 28.2% for other types of headache. No case of cluster headache was found. Almost two thirds of the migraine subjects graded their headaches as severe, while almost 60% of the tension headache subjects and almost 70% of the other headache subjects graded their headaches as mild. Overall, there was higher prevalence in females for migraine and tension headache, and in males for the other types of headache. The prevalence of headache was lower among those younger than 15 and older than 65 years of age. No significant differences were found in the prevalence of headache among the different racial groups nor among the urban versus the rural population. All the headache types shared the same triggering factors suggesting that different physiological characteristics are responsible for the type of pain suffered. In the location of this community with its tropical climate, headache was attributed to sun exposure in 51.9% of the migraine subjects, 55.7% of the tension headache subjects, and 36.6% of the group with other headaches.
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Miliaria crystallina is a transient, superficial obstruction of eccrine sweat ducts resulting in rapidly evolving noninflammatory vesicles. The disease is observed frequently in hot, humid, tropical climates and in the neonatal period, but congenital occurrence is very rare. Miliaria crystallina must be considered in the differential diagnosis of bullous diseases in newborns.
Leptospirosis, a waterborne spirochetal illness, is common in tropical climates. Rodents and wild animals are the most common reservoirs for this widespread zoonosis. Human disease is acquired by contact with urine or tissues of an infected animal or through contaminated water and soil. Systemic leptospirosis is characterized by its multisystem involvement, protean manifestation, and varying severity. The clinical presentation ranges from occult infection to fatal complications like hepatorenal failure. Early diagnosis is important to halt the fulminate course. The microagglutination test is considered the gold standard serological test for leptospirosis, although molecular techniques are now under study. Treatment of systemic leptospirosis includes penicillin or tetracycline in addition to supportive treatment. Ocular involvement occurs during the immunological phase of the disease. One or both eyes may be involved, typically with a panuveitis often accompanied by retinal periphlebitis and hypopyon. In general, leptospiral uveitis has a good prognosis and the patient recovers full vision in spite of severe panuveal inflammation. Awareness of this infectious uveitic entity is essential not only in order to differentiate it from other severe autoimmune uveitides, but also to reduce the percentage of idiopathic uveitis in endemic areas.
Tests were conducted with gelatin granules containing Bayluscide (niclosamide) w.p., 23-3% w/w a.i. Granules rendered a simulated field habitat (banana drain) lethal to Biomphalaria glabrata for 40 days when applied at a rate calculated to give 5 mg/1 in the water. At this dose, Bayluscide e.c. was effective for 8-12 days. Granules exposed to various combinations of natural or simulated tropical climatic factors for up to 56 days gave variable kills of snails, apparently unrelated to the factors tested. The rate at which the molluscicide was released from the granules was affected by climatic factors: high temperatures and low humidities slowed the rate, probably by hardening the granules; rainfall and high humidities accelerated the rate, probably by softening or disintegrating the granules. There was no apparent loss of molluscicidal activity in granules exposed for 56 days to various combinations of climatic factors. The results suggest that this formulation may be applied during droughts to temporary habitats when these are dry and accessible. The molluscicide would then be released at the unpredictable start of the next wet season and kill any snails which survive the drought by aestivation.
A case of culture-proven Haemophilus influenzae type B septicaemia in association with probably Reye's syndrome is presented. This is the second reported case of Reye's syndrome with this organism and the first in a tropical climate. The features of this child's presentation are described and implications for doctors in areas where Haemophilus influenzae infection is common are discussed.
A block randomized clinical trial to compare the efficacy of tepid sponging with the use of paracetamol in febrile children was undertaken at the Queen Elizabeth Central Hospital, Blantyre. Eighty children aged between 6 and 54 months with axillary temperatures of between > or = 38.5 degrees C and < or = 40 degrees C and a clinical diagnosis consistent with upper respiratory tract infection and/or malaria were block randomized to receive either oral paracetamol (15 mg/kg) or tepid sponging. Children receiving tepid sponging were sponged from head to toe (except the scalp) by leaving a thin layer of water on the body. If the body became dry it was repeated and continued until the axillary temperature fell to < 38.5 degrees C. Axillary temperature and assessment of discomfort (convulsions, crying, irritability, vomiting and shivering) were recorded every 30 minutes for 2 hours. A significantly greater and more rapid reduction of fever was demonstrated with paracetamol than with tepid sponging. Tepid sponging without antipyretics is often used to reduce fever, but our results suggest that this is effective only during the 1st 30 minutes. Paracetamol is clearly more effective than tepid sponging in reducing body temperature in febrile children in a tropical climate.
Little published material is available on physical growth in any Sri Lankan population. This paper reports attained mean heights and weights of middle class Tamil children from Jaffna, based on single occasion measurements of 358 boys and 517 girls ranging in age between 6 and 17 years. The cross-sectional height and weight data of both boys and girls show a typical pattern. Boys are taller and heavier up to 9 years, then girls lead in both the measurements due to their pubertal phase of rapid growth. Boys supersede them again when they enter into their rapid growth phase, i.e. in height at 13 years but their mean weights remain lower till 16 years. Thus at 17 years boys on average are 5 cm taller than girls. With reference to British standards the attained means of both boys' and girls' height remain around the 10th centile, but later shift to the 3rd centile. In weight, however, they remain below the 3rd centile and indeed much below the range during the later part of the pubertal phase. Apart from nutrition and living conditions, how much of this pattern is influenced by ethnic and tropical climatic factors is still unclear.
Attained mean heights of well-off North-west Indian children showed close parity with British children up to 12 years in girls and 14 years in boys. Thereafter their attained means become less, resulting in shorter mean adult stature. Comparison of the tempo-unconditional single 1-year velocities of height showed that the total adolescent gain in both the populations was similar. The shorter mean adult height in well-off North-west Indians could be explained by lower height gain per unit RUS bone maturity score advance (growth potential). This may result from tropical climate and lower amounts of circulating calcium.
This lecture draws to the attention of human biologists the opportunities that are available for their participation in international research programmes. Relevant past and present research programmes of the International Union of Biological Sciences are described, together with the larger programmes of the human genome initiative, and the international geosphere biosphere programme on global change of the International Council of Scientific Unions; and the smaller programmes of the World Health Organization and the Council of the European Community. Human biologists have much to contribute to such programmes, but, to do so, personal interests need to be tailored to the requirements of each specific programme.