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PubMed1995

Phenotype differences of STRs in 7 human populations.

A maximum of 6 STR systems (TH01, VWA, ACTBP2, FES, F13B, D21S11) was investigated in 7 human populations (Germans, Turks, Moroccans, Japanese, Chinese, Papuans, Ovambos). In each population no deviations from Hardy-Weinberg equilibrium were observed. Out of each population the phenotypes of 50 individuals (comprising 3 to 6 STRs) were randomly selected. Based on the phenotype frequencies interpopulation comparisons were carried out using the frequencies of each other population. Within major ethnic groups only minor differences in phenotype frequencies were found. Between major ethnic groups differences of up to several orders of magnitude could be observed. The most discriminative STRs for interpopulation comparisons were TH01, FES and F13B.

China↗
PubMed2005

The night-time temporal window of locomotor activity in the Namib Desert long-distance wandering spider, Leucorchestris arenicola.

Even though being active exclusively after sunset, the male Leucorchestris arenicola spiders are able to return to their point of departure by following bee-line routes of up to several hundreds of meters in length. While performing this kind of long-distance path integration they must rely on external cues to adjust for navigational errors. Many external cues which could be used by the spiders change dramatically or disappear altogether in the transition period from day to night. Hence, it is therefore imperative to know exactly when after sunset the spiders navigate in order to find out how they do it. To explore this question, we monitored their locomotor activity with data loggers equipped with infrared beam sensors. Our results show that the male spiders are most active in the period between the end and the beginning of the astronomical twilight period. Moreover, they prefer the moonless, i.e. darkest times at night. Hence, we conclude that the males are truly-and extremely-nocturnal. We further show that they are able to navigate under the very dim light conditions prevailing on moonless nights, and thus do not have to rely on the moon or on moon-related patterns of polarised light as potential compass cues.

Animals↗
PubMed1999

Brain, abdominal and arterial blood temperatures of free-ranging eland in their natural habitat.

Using implanted miniature data loggers we measured brain, arterial blood and abdominal temperatures at 5-min intervals in two free-ranging eland (Tragelaphus oryx) in their natural habitat. The animals were subjected to a nychthemeral range of globe temperature which exceeded 40 degrees C. Arterial blood exhibited a moderate amplitude (2.3 degrees C) nychthemeral rhythm, with a temperature peak at 1600-1800 hours, and a trough in the early morning at 0600-0800 hours. Mean abdominal temperature was 0.2-0.3 degrees C lower than the corresponding blood temperature, and had a peak-to-trough amplitude of 2.6 degrees C. Brain temperature closely paralleled changes in blood temperature but usually exceeded blood temperature by about 0.5 degrees C. Sporadic episodes of selective brain cooling occurred in one animal, but the duration and magnitude of such cooling was small (less than 0.4 degrees C), and took place only well above the mode of blood temperature. Our results do not support the concept that eland routinely employ adaptive heterothermy and selective brain cooling to survive in their natural environment.

Abdomen↗
PubMed1996

Complex mutational events at the HumD21S11 locus.

We have studied length and sequence variability at the HumD21S11 locus in five different populations to obtain more detailed information about the structure of this short tandem repeat system. In all populations studied so far two types of alleles have been described. The consensus alleles (type I) consist of three regions with variable numbers of TCTR units and one constant region comprising 43 bp. Alleles of type II (so-called interalleles) show the same basic sequence structure except for the occurrence of a TA insertion at a fixed position in variable region 3. Additional sequence variability exists in the Ovambo and Papuan populations with gross changes in two of the three variable regions and in the constant region. Due to these extreme variations the Ovambos and Papuans showed a better fit to the infinite allele model than to the stepwise mutation model. In the German, Japanese and Chinese populations no significant bias towards one of the two models could be observed. Population genetic studies showed no significant deviation from Hardy-Weinberg equilibrium.

Alleles↗
PubMed2005

Analysis of genetic polymorphism of deoxyribonuclease I in Ovambo and Turk populations using a genotyping method.

Deoxyribonuclease I (DNase I) polymorphism has been used as a valuable marker in genetic and clinical investigations. Six codominant alleles are known for DNase I, DNASE1*1, *2, *3, *4, and the recently discovered alleles *5 and *6. To detect these two new alleles, we added a new DNase I genotyping method based on both an allele-specific amplification and mismatched polymerase chain reaction (PCR). These methods were used to examine the distribution of DNase I genotypes in unrelated individuals from bloodstains of Ovambo and Turkish populations. The DNASE1*1 allele was found to be most dominant in the Ovambos. In contrast, Turks showed the highest allele frequency for DNASE1*2. This study is the first to demonstrate that there is a certain genetic heterogeneity in the worldwide distribution of DNase I polymorphism using the genotyping method of human DNase I polymorphism with PCR.

Asian People↗
PubMed2004

Connecting community action and science to combat desertification: evaluation of a process.

Combating desertification requires the involvement of many people ranging from communities who experience the effects on a daily basis and scientists attempting to understand the biophysical and socio-economic causes and consequences of desertification, to developers and policy makers on all levels. In many instances, however, the understanding, approaches and actions of these different groups contradict rather than support one another. Over the period 2000 to 2002, a conference process undertaken in southern Africa brought together communities, scientists, and development workers to test the concept that they could connect and work together to combat desertification, given an appropriate framework. The conference was a success, and communities, scientists and developers did exchange experience, knowledge and information. Many lessons were learned, although some pitfalls were experienced. Time, funding, enhanced communication, and good will are the primary ingredients for ensuring that different sectors complement one another in their efforts to combat desertification.

Community Participation↗
PubMed2006

Resistance and tolerance of Terminalia sericea trees to simulated herbivore damage under different soil nutrient and moisture conditions.

Resource availability, degree of herbivore damage, genetic variability, and their interactions influence the allocation of investment by plants to resistance and tolerance traits. We evaluated the independent and interactive effects of soil nutrients and moisture, and simulated the effects of herbivore damage on condensed tannins (resistance) and growth/regrowth (tolerance) traits of Terminalia sericea, a deciduous tree in the Kalahari desert that constitutes a major component of livestock diet. We used a completely crossed randomized-block design experiment to examine the effects of nutrients, water availability, and herbivore damage on regrowth and resistance traits of T. sericea seedlings. Plant height, number of branches, internode length, leaf area, leaf mass for each seedling, combined weight of stems and twigs, and root mass were recorded. Condensed tannin concentrations were 22.5 and 21.5% higher under low nutrients and low soil moisture than under high nutrient and high water treatment levels. Tannin concentrations did not differ significantly between control and experimental seedlings 2 mo after simulated herbivore damage. Tannin concentrations correlated more strongly with growth traits under low- than under high-nutrient conditions. No trade-offs were detected among individual growth traits, nor between growth traits and condensed tannins. T. sericea appeared to invest more in both resistance and regrowth traits when grown under low-nutrient conditions. Investment in the resistance trait (condensed tannin) under high-nutrient conditions was minimal and, to a lesser degree, correlated with plant growth. These results suggest that T. sericea displays both resistance and tolerance strategies, and that the degree to which each is expressed is resource-dependent.

Adaptation, Biological↗
PubMed1991

The landmine foot: its description and management.

The injuries of 54 patients involved in landmine explosions are described. In 72 per cent the injuries affected the mid- and hindfoot. Of these injuries, 67 per cent were open fractures involving the calcaneus. The injury resulted in the 'landmine foot', an entity not previously described. Its clinical features and orthotic management are described. The prognosis of 'landmine foot' was generally favourable in this Third World setting, with adequate rehabilitation provided by a customized surgical boot.

Adolescent↗
PubMed1994

The management of penetrating injuries of the anterior triangle of the neck.

The management of penetrating injuries of the anterior triangle of the neck is controversial and poses several problems. A policy of mandatory neck exploration of these injuries is followed in the Department of General Surgery at the State Hospital, Windhoek. A retrospective study of patients presenting to one of the four surgical firms at The State Hospital was performed to see if this policy was justified. Twenty-seven patients were reviewed of which 25 presented acutely and two presented late with severe complications. The clinical and operative findings and the mortality rate of 7 per cent were similar to previous reports. The negative exploration of 30 per cent was less than previous reports of mandatory neck exploration for penetrating trauma. This may have been because exploration was limited to injuries involving the anterior triangle of the neck in this series. All 14 patients with positive clinical findings were found to have injuries at exploration and five of 13 patients (38 per cent) with no clinical signs were found to have injuries. Given these results and in the setting of The State Hospital it was felt that the policy of mandatory exploration was justified.

Acute Disease↗
PubMed1978

Studies on the intestinal parasites in African patients in Owamboland, South West Africa.

The paper gives the results of a survey of intestinal parasites among 501 in-patients drawn from four mission hospitals in Owambo and Kavango in northern South West Africa. Most of the patients (90%) were examined twice by the formol-ether concentration method, while the remaining 10% had one stool specimen examined. 10 species of helminths and 3 species of potentially-pathogenic protozoa were recorded--Necator americanus, Strongyloides stercoralis, Strongyloides fuelleborni, Hymenolepis nana, Taenia saginata, Trichuris trichura, Enterobius vermicularis, Fasciola gigantica, Schistosoma mansoni and S. haematobium, and Entamoeba histolytica, Giardia lamblia and Balantidium coli. The loads of Necator americanus were recorded in a few cases. The results are compared with those of some other Central and Southern African countries. 96 blood smears were examined for filaria and 46 patients were tested for bilharzia using the bilharzial skin test. Both groups gave only negative results.

Hookworm Infections↗
PubMed1993

Primary amoebic meningo-encephalitis in southern Africa.

A fatal childhood case of confirmed primary amoebic meningo-encephalitis due to Naegleria fowleri is reported. This appears to be the first such case identified in southern Africa. The diagnosis and management of this unusual and lethal infection is discussed and attention is drawn to the possible danger of swimming in contaminated warm water.

Amebiasis↗
PubMed1985

Depressive symptomatology among Namibian adolescent refugees.

Symptoms of depression have been considered rare in sub-Saharan populations. Using a standard assessment measure of depressive symptomatology, the Beck Depression Inventory, the prevalence of symptoms of depression was obtained from a group (N = 56) of Namibian refugees residing in a sub-Saharan host country. Contrary to expectations, the rates of self-reported symptoms were quite frequent, with many symptoms reported as moderate or severe by a large proportion of these youths. Using a stress model to explore these data, it was demonstrated that social support ameliorated the effects of chronic stress, as represented by the length of time in exile. It is argued that adaptation, acculturation, and adolescent developmental demands result in self-reports of depressive symptoms. These demands, however, are lessened in intensity by a strong social support system that is especially helpful early in the exile period.

Adolescent↗
PubMed1987

Relationship of chronic stress, social support, and coping style to health among Namibian refugees.

This study investigates how social support and coping style affect the relationship between a traumatic chronic stressor and health status. A population of 88 Namibian refugees living in an equatorial region of Africa participated in the study. The central hypothesis was that social support and coping style moderate the relationship between length of stay in exile (a proxy measure of chronic stress) and health status (symptoms of generalized anxiety disorders, self-reported physical health status and length of stay in hospital). The results show that when social support is high the relationship between length of stay in exile and all three health outcomes is substantially reduced. When social support is low, the relation between stress and poor health outcomes is high. Coping style moderates the relationship between length of stay in exile and period of hospitalization but has no effect on level of anxiety or perceived health status. When both social support and coping style are simultaneously considered, the best results emerge.

Adaptation, Psychological↗
PubMed1995

Neoproterozoic variations in the C-isotopic composition of seawater: stratigraphic and biogeochemical implications.

The recent proliferation of stratigraphic studies of delta 13C variation in carbonates and organic C in later Neoproterozoic and basal Cambrian successions (approximately 850-530 Ma) indicates a strong oscillating trend in the C-isotopic composition of surface seawater. Alone, this trend does not adequately characterize discrete intervals in Neoproterozoic time. However, integrated with the vectorial signals provided by fossils and Sr-isotopic variations, C isotope chemostratigraphy facilitates the interbasinal correlation of later Neoproterozoic successions. Results of these studies are evaluated in terms of four stratigraphic intervals: (1) the Precambrian/Cambrian boundary, (2) the post-Varanger terminal Proterozoic, (3) the late Cryogenian, and (4) the early Cryogenian. Where biostratigraphic or radiometric data constrain the age of Neoproterozoic sedimentary sequences, secular variations in C and Sr isotopes can provide a level of stratigraphic resolution exceeding that provided by fossils alone. Isotopic data place strong constraints on the chemical evolution of seawater, linking it to major tectonic and paleoclimatic events. They also provide a biogeochemical framework for the understanding of the initial radiation of macroscopic metazoans, which is associated stratigraphically, and perhaps causally, with a global increase in the burial of organic C and a concomitant rise of atmospheric O2.

Canada↗
PubMed1995

The Tygerberg Hospital Children's Tumour Registry 1983-1993.

This study records the disease profile and outcome of all 492 children with confirmed cancer below the age of 15 who were admitted to Tygerberg Hospital, South Africa, from 1983 to 1993. The black (48.3%), so-called coloured (30.3%) and caucasian (21.3%) children did not represent a confined geographical area. Leukaemia (22.8%), brain tumours (20.5%), lymphomas (15.2%), nephroblastomas (10%), neuroblastomas (8.5%) and retinoblastomas (5.7%) were the most common tumours. All children were treated with standard protocols and included in the Kaplan-Meier survival analyses. 14 patients were lost to follow-up. Projected survival in (acute lymphoblastic leukaemia) ALL was 63% in white children, but only 17% in black children. Survival was 65% in stage 1 and 2 Wilms' tumour, and exceeded 50% in medulloblastoma and astrocytoma. So-called African Burkitt's lymphoma occurred in all population groups. Overall, 5-year survival in Hodgkin's disease was 70%. Black and coloured children with neuroblastoma presented mainly with stage 3 and 4 disease. All 26 black and coloured children with retinoblastoma had a negative family history and advanced disease which needed enucleation.

Adolescent↗
PubMed2004

Color categories: evidence for the cultural relativity hypothesis.

The question of whether language affects our categorization of perceptual continua is of particular interest for the domain of color where constraints on categorization have been proposed both within the visual system and in the visual environment. Recent research (Roberson, Davies, & Davidoff, 2000; Roberson et al., in press) found substantial evidence of cognitive color differences between different language communities, but concerns remained as to how representative might be a tiny, extremely remote community. The present study replicates and extends previous findings using additional paradigms among a larger community in a different visual environment. Adult semi-nomadic tribesmen in Southern Africa carried out similarity judgments, short-term memory and long-term learning tasks. They showed different cognitive organization of color to both English and another language with the five color terms. Moreover, Categorical Perception effects were found to differ even between languages with broadly similar color categories. The results provide further evidence of the tight relationship between language and cognition.

Adolescent↗