Sociocultural influences on infant feeding decisions among HIV-infected women in rural Kwa-Zulu Natal, South Africa

The promotion of exclusive breastfeeding for 6 months, followed by rapid transition to alternative food sources may be an important public health approach to the reduction of mother-to-child transmission of HIV through breastmilk. The basic ethical principle of 'informed choice' requires that HIV positive women are provided with adequate information about their options. However, information is only one factor that affects their decisions. The objective of this ethnographic study was to identify sociocultural influences on infant feeding decisions in the context of a large cohort study designed to assess the impact of a breastfeeding counselling and support strategy to promote exclusive breastfeeding on postnatal transmission of HIV in African women. Following an initial period of exploratory interviewing, ethnographic techniques were used to interview 22 HIV positive women about their views on infant feeding and health. Interviews were tape-recorded, transcribed and analysed with a text analysis program. Five themes of influences on feeding decisions emerged: (1) social stigma of HIV infection; (2) maternal age and family influences on feeding practices; (3) economic circumstances; (4) beliefs about HIV transmission through breastmilk; and (5) beliefs about the quality of breastmilk compared to formula. The study highlights the role of cultural, social, economic and psychological factors that affect HIV positive women's infant feeding decisions and behaviour.     

Reconstitution of a human immune system in immunodeficient mice: models of human alloreaction in vivo

Rodents have been widely used for studies in transplantation immunology because of their short reproduction period and the relative ease of generating inbred mutant or transgenic strains. However, although many biological mechanisms are similar between rodents and humans, several features clearly distinguish the immune system in these species. Consequently, it is rarely possible to extrapolate observations from rodent models directly into clinical practice. In vitro studies with human cells are useful for elucidation of basic mechanisms, but in order to study complex biological phenomena, in vivo studies are indispensable. In later years, a number of interesting models have been described where immunodeficient mice have been reconstituted with human cells, so-called humanized mice, in order to study human immune responses in vivo. This has opened a new field of experimental immunology that has been applied to areas such as cancer, autoimmunity, allergy, infections, and transplantation biology. In this review, we shall concentrate on the use of severe combined immunodeficient mice reconstituted with human immune or stem cells for studies of human alloreaction in vivo.     

Change in permeation parameters and the decontamination efficacy of three chemical protective gloves after repeated exposures to solvents and thermal decontaminations

BACKGROUND: Chemical protective clothing (CPC) and gloves, which provide adequate protection, are usually too expensive to be considered disposable. Repeated use of CPC without effective decontamination may result in secondary exposure and injury. However, decontamination may change the physical and/or chemical properties of the barrier material, causing variations in breakthrough time (BT) and steady-state permeation rate (SSPR). METHODS: Glove materials including neoprene, Guardian butyl rubber, and nitrile synthetic rubber were selected for this study. Toluene and acetone were chosen as the challenge chemicals. Permeation was measured in a closed loop system using a 2.5 cm permeation cell and a MIRAN infrared analyzer (Foxboro, MA). Following the permeation test, the samples were thermally decontaminated. After each exposure/decontamination cycle, BT and SSPR were measured. A total of 260 permeation tests were conducted. Permeation test results were collected on each material/chemical combination for up to 10 exposure/decontamination cycles. RESULTS: On average, changes in BT and SSPR in comparison with respect to new swatches were 11.5% and 13.7% after seven exposure/decontamination cycles. The percentages increased to 26.6% and 15.9% after 10 exposure/decontamination cycles, respectively. For at least seven cycles, the BT mean for four out of five material/chemical combinations tested (neoprene/acetone, neoprene/toluene, nitrile/acetone, and nitrile/toluene) was not significantly different from the original value of the BT for each corresponding swatch. Similarly, the SSPR mean for each of the five material/chemical combinations after at least five cycles was not significantly different from those for new swatches. The BT mean for the butyl/toluene combination, however, was significantly different from the new swatches even after the first exposure/decontamination. The SSPR mean was significantly different after five cycles compared to the new swatches. CONCLUSIONS: Except for the butyl/toluene combination, thermal decontamination was an effective method in removing the solvents from the matrix of selected glove materials. Multiple reuses of some chemical protective gloves could be safe if effective decontamination methods are used and the glove materials do not have significant degradation.     

Protective behavior and West Nile virus risk

We conducted a cross-sectional, household survey in Oakville, Ontario, where an outbreak of West Nile virus (WNV) in 2002 led to an unprecedented number of cases of meningitis and encephalitis. Practicing > or =2 personal protective behavior traits reduced the risk for WNV infection by half.     

A review of sharps injuries and preventative strategies

Exposure to bloodborne pathogens from sharps injuries continues to pose a significant risk to healthcare workers (HCW). The number of sharps injuries sustained by HCW is still unclear, primarily due to under-reporting. In this review a mean rate of 4.0% (range 1.0-6.2%) sharps injuries per 10000 HCW was calculated from eight studies involving more than 7000 HCW. Nurses and doctors were most at risk of sharps injuries, frequently from hollow-bore needles. Approaches to reduce this risk have included education and training on the safe handling and disposal of sharp devices, awareness campaigns and legislative action. More recently, preventative strategies have focused on needle protective devices, which may reduce the rate of sharps injuries. Introducing needle protective devices should be considered particularly in high-risk areas, after training, education, evaluation and cost-benefit analysis.     

Designing radiotherapy plans with elastic constraints and interior point methods

A new linear programming model used to aid in the design of radiotherapy plans is introduced. This model incorporates elastic constraints, and when solved with a path following interior point method, produces favorable plans. A sound mathematical analysis shows how to interpret the solution, and hence, the treatment planner receives meaningful knowledge about the radiotherapy plan being developed. Preliminary experiments are conducted.     

The analysis of contingency tables with ordinal data: an application to monitoring antibiotic resistance

Rationalization of antibiotic therapy in the management of infectious diseases is helped by a knowledge of the patterns of sensitivity and resistance of bacteria to antibiotics and their possible changes both in time and from one hospital unit to another. In this paper we present the results regarding the sensitivities of several groups of bacteria and different Units of the S.Orsola-Malpighi Hospital of Bologna in the period 1995-1997. We apply recent methods of analysis of ordinal contingency tables that rely on stochastic ordering of the rows to test the assumption that a decrease (or increase) in sensitivity of bacteria to specific antibiotics has taken place against the alternative that no such thing has happened. In most cases the results seem to indicate an increase in sensitivity rather than what was expected, namely the opposite.     

Pesticide use and safety practices among Greek tobacco farmers: a survey

An attempt was made to explore knowledge, attitudes, and practices towards safety issues of pesticide handling among tobacco farmers of the rural area of Pieria in northern Greece. From the 310 survey questionnaires that were mailed out, 223 were received fully and correctly completed resulting in a quite satisfactory response rate of 72%. A large majority of the farmers (96%) viewed pesticides as a guarantee for high tobacco yields and high product quality. Almost all farmers (99%) thought that pesticides can have serious adverse effects on users' health. Skin contact was recognized as the most common route of exposure during pesticide use (58%). Despite awareness of potential health risks by pesticide handling, a significant proportion of the farmers (46%) reported not using any special protective equipment when spraying pesticides. From those who reported that they use protective equipment, most stated that they normally use a hat (47%) and boots (63%). Only few farmers reported using a face mask (3%), gloves (8%), and coveralls (7%) on a regular basis. The reasons for not using protective equipment during pesticide handling were that protective equipment is uncomfortable (68%), too expensive to buy (17%), time-consuming to use (8%), not available when needed (6%), and not necessary for each case (2%). A large majority of the farmers (84%) said that they replace work clothing when it wears out and a considerable part (48%) stated that they wash work clothing after several uses. Although farmers' knowledge of potential hazards by pesticide use was high, the reported safety measures were poor. Continuous emphasis on the basic safety precautions required when using pesticides and on the importance of protective equipment is essential for changing wrong habits of farmers which can be hazardous for their health.     

The cytotoxic effect of anthrax lethal toxin on human lung cells in vitro and the protective action of bovine antibodies to PA and LF

The excretion of protein toxins by vegetative cells of Bacillus anthracis is critical to the development of the lethal consequences of anthrax, particularly inhalational anthrax. Whilst the lung macrophages and other phagocytic cells transfer the spores from the lung cavities into the lymphatic system, and provide an initial germination site for the proliferation of the vegetative cells, it appears that much of the tissue pathology at the time of the host's death could be due to the action of the toxins, especially lethal toxin-protective antigen (PA) plus lethal factor (LF). The widespread tissue oedema and hypoxia may in part reflect a direct attack by lethal toxin on vascular endothelial cells. Also the distribution of the receptor for PA on a variety of cell types including epithelial cells as well as endothelial cells, and the involvement of the lungs in the pathology raises the question of whether lung epithelial cells are also susceptible to lethal toxin. To investigate this possibility a series of in vitro cytotoxicity experiments were carried out with human lung epithelial cells and microvascular endothelial cells. In these experiments lethal toxin (PA 500 ng ml(-1) plus 10-100 ng ml(-1) LF) was shown to cause a progressive loss of cell viability that developed slowly over at least 3 days. Affinity purified bovine colostrum antibodies for both PA and LF were equally effective in providing a 100% protection for epithelial cells from this cytotoxic action of lethal toxin. This was achieved at a 10:1 molar ratio of the particular antibody to its respective target.