Molecular simulation of a model of dissolved organic matter

A series of atomistic simulations was performed to assess the ability of the Schulten dissolved organic matter (DOM) molecule, a well-established model humic molecule, to reproduce the physical and chemical behavior of natural humic substances. The unhydrated DOM molecule had a bulk density value appropriate to humic matter, but its Hildebrand solubility parameter was lower than the range of current experimental estimates. Under hydrated conditions, the DOM molecule went through conformational adjustments that resulted in disruption of intramolecular hydrogen bonds (H-bonds), although few water molecules penetrated the organic interior. The radius of gyration of the hydrated DOM molecule was similar to those measured for aquatic humic substances. To simulate humic materials under aqueous conditions with varying pH levels, carboxyl groups were deprotonated, and hydrated Na+ or Ca2+ were added to balance the resulting negative charge. Because of intrusion of the cation hydrates, the model metal-humic structures were more porous, had greater solvent-accessible surface areas, and formed more H-bonds with water than the protonated, hydrated DOM molecule. Relative to Na+, Ca2+ was both more strongly bound to carboxylate groups and more fully hydrated. This difference was attributed to the higher charge of the divalent cation. The Ca-DOM hydrate, however, featured fewer H-bonds than the Na-DOM hydrate, perhaps because of the reduced orientational freedom of organic moieties and water molecules imposed by Ca2+. The present work is, to our knowledge, the first rigorous computational exploration regarding the behavior of a model humic molecule under a range of physical conditions typical of soil and water systems.     

Envenomation accidents caused by snakebites in the surgical emergency unit of Gabriel-Touré Hospital, Bamako, Mali (1998-1999)

This study aimed at assessing envenomations caused by snakebite in the Gabriel Touré hospital between January 1998 and December 1999. We included in total 112 victims of snakebites proved by the identification of the snake, the fangs traces and envenomation signs. The bites concerned 34 women (30.36%) versus 78 men (69.64%) from the Bamako district, while 66.7% were from a rural environment. The farmers were the most affected category (35.1%). The bite concerned the lower limb in 83.3% of the cases. Snakes such as Echis ocellatus, Bitis arietans, Naja nigricollis and N. katiensis caused the envenomations. The viperine syndrome dominated the clinical picture; its severity depended on the bleeding stage and the delay of administration of the antivenom serum (AVS) after the envenomation: 19 hours for Echis sp. and 2 hours for Naja sp. This study shows that the envenomation accidents caused by snakes are frequent with a lethality rate of 9.8%.     

Domestic transmission of Rift Valley Fever virus in Diawara (Senegal) in 1998

In 1998, circulation of the Rift Valley Fever (RVF) virus was revealed in Diawara by detection of IgM antibodies in sheep and isolation of the virus from mosquitoes caught outside a village. A seroprevalence study was carried out. Finger-prick blood samples, individual and collective details were obtained. One thousand five hundred twenty people (6 months - 83 years) were included. Overall prevalence in this group was approximately 5.2%. The prevalence in infants (6 months - 2 years) was 8.5%. Age, gender, contact with a pond, presence of sheep, and abortion among sheep, and individual or collective travel history were not statistically associated with prevalence. Prevalence increased significantly when the distance to a small ravine, located in the middle of the village, decreased. The results suggest a low, recent, not endemic circulation of the virus. Culex quinquefasciatus was captured near the ravine. This mosquito, similar to Culex pipiens, can play a similar role in human-to-human transmission of the RVF virus.     

Epidemiology of eye injuries in Abidjanian children

Eye injuries, most of them preventable, are particularly severe in Africa, because of the risks of infection and delay in treatment. We report a 16-month (March 1997-June 1998) prospective observational survey of eye injuries in children up to the age of 15 years at Treichville-Abidjan University Hospital. During this period, 62 children were treated for these injuries. Ocular traumas represented 4% (n = 245) of new admissions in ophthalmology, and 29% of these injuries occurred in children. The sex ratio was 5:2 boys to girls, and their mean age was 8.66 +/- 3.56 years. Eye injuries occurred most often during play (84%, n = 52). More than 85% (n = 53) of children were alone or without adult supervision at the time of the injury. The causal agent was most often wood (35%) followed by metal (29%). The mean time from injury to hospital admission was 1.8 +/- 0.77 day. Only 19% of patients were admitted the day of injury. Most patients (66%) first sought treatment in a primary care centre. More than 70% (n = 44) of injuries necessitated hospitalisation. Open eyeball wounds were the most common injury (53%) and were associated with endophthalmitis in 16%. The mean recovery of visual acuity was 0.1. At admission, 40 of the injured eyes (64.5%) had monocular blindness; six recovered, for a final blindness rate of 55%. Injuries associated with wooden objects had a final blindness rate of 77% and play-related injuries 63%. The primary posttraumatic sequelae were corneal scars. Eyeball phthysis (14.5%) was secondary to 8 open wounds of the eyeball and one postcontusion retinal detachment. Eye injuries remain a major cause of monocular blindness in children in Cote d'Ivoire. Most of them can be prevented by relatively simple measures including supervision of children and rapid hospitalisation when injury occurs.     

Season of birth is not associated with risk of early adult death in rural Senegal

BACKGROUND: In a rural area of the Gambia, West Africa, young adults born in the 'hungry' season had a high excess of deaths (mortality ratios (MR): 3.7 from 14.5 years and 10.3 from 25 years, P < 0.0001). Among several potential causal factors, fetal undernutrition was considered the most plausible. This study is a similar analysis of children and young adults living in rural Senegal, close to the Gambia. METHODS: A cohort of 9192 subjects born 1962-2001 with prospectively collected dates of birth and death was analysed. MR by season of birth (July-December/January-June) was estimated using Cox's proportional hazards analysis. The nutritional status of non-pregnant women was analysed at monthly intervals 1990-1996. RESULTS: MR by season of birth was slightly greater than 1 during infancy, and close to 1 from 1-5 years and from 5-14.5 years. From 14.5 years old the MR was 0.77 (95% CI: 0.47, 1.25, P = 0.29), compared with 0.53 (95% CI: 0.28, 1.02, P = 0.056) from 20 years and 0.33 (95% CI: 0.09, 1.25, P = 0.10) from 25 years. The weight of women varied strongly by season: means were 3.0-3.9 kg lower at the end of the rainy season (September-November) than during the dry season (February-May, P < 0.001 for each year). CONCLUSIONS: This study found no increased risk of death among young adults born during the hungry season in a rural West African area despite large seasonal variations in women's nutritional status. The strongly increased risk in adult Gambians is probably not explained by fetal undernutrition.     

Childhood mortality and probable causes of death using verbal autopsy in Niakhar, Senegal, 1989-2000

BACKGROUND: In African rural settings, medically certified information on causes of death is largely lacking. The authors applied the verbal autopsy to identify causes of death before 15 years old in a rural area of Senegal where a demographic surveillance system is operating. METHODS: Between 1989 and 2000, a postmortem interview was conducted using a standardized questionnaire which was independently reviewed by two physicians who assigned the probable underlying cause of death. Discordant diagnoses were discussed by a panel of physicians. Causes of death were grouped into a few categories; cause-specific mortality rates and fractions were generated. RESULTS: Between 1989 and 1997, all-cause mortality fluctuated. Diarrhoeal diseases, malaria and acute respiratory infections explained between 30% and 70% of the mortality before 10 years of age. In children 1-9 years old, malaria death rate increased between 1989 and 1994 and thereafter did not change. The 1998-2000 years were marked by a peak in mortality, attributed to a meningitis outbreak in children more than one year old paralleled by an increase in death rate from fever of unknown origin, diarrhoeal diseases, and acute respiratory infections in children under 5 years. CONCLUSIONS: Verbal autopsy provided useful information on the mortality structure responsible for the 1998-2000 peak in mortality. It underlined that, outside outbreak situations, malaria was a leading cause of death for 1-9 year old children and that diarrhoea, acute respiratory infections, or fever from unknown origin accounted for up to 50% of the deaths among the children under 5 years.     

Estrogen receptor alpha and beta, progesterone receptor, pS2 and HER-2/neu expression delineate different subgroups in ductal carcinoma in situ of the breast

Antiestrogen therapy of ductal carcinoma in situ (DCIS) has become a more common option in reducing risk of developing invasive cancer. Previously, estrogen receptor alpha (ER-alpha) was evaluated as the only predictive factor. Immunohistochemical staining was performed for ER-alpha, estrogen receptor ER-beta, progesterone receptor (PR), pS2 and her-2/neu in 59 cases of ductal carcinoma in situ (DCIS). We observed a positive correlation between the expression of ER-alpha (p=0.003), PR (p<0.001) and histopathological grading. Of the DCIS, 61.5% of ER-beta positive (p=0.046) and 35.5% of PR positive samples showed a coexpression with pS2, whereas 72.1% of pS2 negative DCIS were also negative for ER-beta and 92.9% of PR negative DCIS were negative for pS2 (p=0.012). In contrast, 50.0% of her-2/neu negative DCIS expressed ER-beta receptor (p=0.052). We propose that there are subpopulations of DCIS which can be described by distinct endocrine-associated expression patterns.     

Epidemiology of malaria in a village of Sudanese savannah area in Mali (Bancoumana). 2. Entomo-parasitological and clinical study

We carried out five cross sectional surveys between 1993 and 1994 to assess the epidemiology of malaria in the village of Bancoumana, located in the Sudanese savannah areas of Mali. Each survey included a collection of entomological, clinical, parasitological and immunological data. The study population involved 1600 children from six months to 9 years of age. The main vector was Anopheles gambiae s.l., man bite rate and entomological inoculation rate were maximum respectively in August (peak of the transmission season) and October (end of transmission season). Plasmodium. falciparum was the main parasite species observed. Spleen enlargement rate, parasite rate, gametocyte rate and parasite density varied significantly with age and season. The parasite rate, gametocyte rate and parasite density were significantly low in October 1994 compared with October 1993 while the entomologic parameter did not show any variation over the two years. This reduction of parasitologic index between 1993 and 1994 may be related to an increase of anti-malarial drug use in the population. Our results show that malaria is hyperendemic in the village of Bancoumana.     

Lymphangioma of the ovary after radiation due to Wilms' tumor in the childhood

OBJECTIVE: To report a case of lymphangioma of the ovary after radiation due to Wilms' tumor in the childhood. PATIENT: A 19-year-old nulliparous female. INTERVENTIONS: The vaginal ultrasound showed the left ovary enlarged to 4.4 cm x 2.9 cm x 4.5 cm in size including a 3.5 cm x 2.6 cm x 3.2 cm measuring cystic solid tumor without hypervascularity. For exclusion of a malignant tumor, a laparoscopy for excision of the tumor and deep incision of the left ovary with a bipolar needle was performed to exclude deeper tumor of stromal origin. The histological examination of the tissue showed a lymphangioma beside normal ovarian tissue. CONCLUSION: To our knowledge, this is the first report of lymphangioma of the ovary after radiation due to Wilms' tumor in the childhood. The impact of this finding on the patient's fertility remains unclear. As in other organs exposed to radiation, lymphangioma can also occur in the ovary. Careful follow up should be considered to this patients, because malignant transformation can not be excluded.