Science for medicine--time for another reappraisal.

The Amendments to the National Cancer Act of 1974 included a provision for a comprehensive review of the Federal policies and programs for medical research. This would appear to be a particularly timely review since many of the fundamental issues concerning the Government's role in biomedical research are presently in question. These issues include the rationale for public support for basic medical research, public expectations for returns on these investments, establishment of priorities among various research avenues, and a number of derivative as well as ethical questions. Since the professional and scientific communities have been historically successful in gaining public funds for research, a periodic opportunity for public review and consideration would appear to be highly desirable.     

Biofortification for combating 'hidden hunger' for iron

Micronutrient deficiencies are responsible for so-called 'hidden undernutrition'. In particular, iron (Fe) deficiency adversely affects growth, immune function and can cause anaemia. However, supplementation of iron can exacerbate infectious diseases and current policies of iron therapy carefully evaluate the risks and benefits of these interventions. Here we review the approaches of biofortification of valuable crops for reducing 'hidden undernutrition' of iron in the light of the latest nutritional and medical advances. The increase of iron and prebiotics in edible parts of plants is expected to improve health, whereas the reduction of phytic acid concentration, in crops valuable for human diet, might be less beneficial for the developed countries, or for the developing countries exposed to endemic infections.     

Breeding for abiotic stresses for sustainable agriculture

Using cereal crops as examples, we review the breeding for tolerance to the abiotic stresses of low nitrogen, drought, salinity and aluminium toxicity. All are already important abiotic stress factors that cause large and widespread yield reductions. Drought will increase in importance with climate change, the area of irrigated land that is salinized continues to increase, and the cost of inorganic N is set to rise. There is good potential for directly breeding for adaptation to low N while retaining an ability to respond to high N conditions. Breeding for drought and salinity tolerance have proven to be difficult, and the complex mechanisms of tolerance are reviewed. Marker-assisted selection for component traits of drought in rice and pearl millet and salinity tolerance in wheat has produced some positive results and the pyramiding of stable quantitative trait locuses controlling component traits may provide a solution. New genomic technologies promise to make progress for breeding tolerance to these two stresses through a more fundamental understanding of underlying processes and identification of the genes responsible. In wheat, there is a great potential of breeding genetic resistance for salinity and aluminium tolerance through the contributions of wild relatives.     

Training for best practices for agricultural programs

As with other areas of animal research, ensuring the proper training and qualifications of the individuals working with agricultural animals for use in research, teaching, and testing is critical to both animal welfare and the successful outcome of the study or teaching exercise. The author provides guidance for the development of appropriate training programs for organizations that use agricultural animals in research.     

Risk factors for rejection for morphological reasons of heart valves for transplantation

The study aim was to identify risk factors for morphological rejection of aortic and pulmonary valves for transplantation that could be used to optimize donor selection. The files of all Dutch heart valve donors, donating in a 2.5 years period, whose hearts were processed at Heart Valve Bank Rotterdam, were reviewed for all factors that could be relevant for valve rejection and related to outcome of morphological assessment of the valves. Valves were retrieved from 813 deceased Dutch donors, 24.1% also donating organs. For 797 aortic and 767 pulmonary valves, who met retrieval criteria, morphological assessment was done. 69.5% of aortic and 37.5% of pulmonary valves were considered unsuitable for transplantation at morphological assessment. Backward stepwise multivariate logistic regression analysis, showed age, cardiac cause of death, cerebrovascular accident as cause of death or in medical history, and number of cardiovascular risk factors in a donor to be independent risk factors for morphological rejection of aortic valves. Age, sex, weight >100 kg and ruptured aortic aneurysm as cause of death were independent risk factors for morphological rejection of pulmonary valves. Being an organ donor was an independent predictor of morphological approval of aortic and pulmonary valves, while hypertension was an independent predictor for morphological approval of aortic valves. Thus, independent factors were identified that are associated with morphological rejection of aortic and pulmonary valves for transplantation, and that could be used to optimize donor selection by preventing unnecessary retrievals, limiting costs, while improving yield per donor with minimal compromise for availability.     

Searching for a function for nuclear actin

The abundant cytoskeletal protein actin has numerous cytoplasmic roles. Although there are many reports of the presence of actin in the nucleus, in general they have been discounted as artifactual. However, recent work has begun to provide evidence for important roles for actin in nuclear processes ranging from chromatin remodelling to splicing. In addition, several regulators of actin polymerization are localized to the nucleus or translocate to the nucleus in a regulated manner, suggesting that there is some function of actin in the nucleus that is subject to regulation. This review discusses the evidence for actin in the nucleus and summarizes recent work suggesting that actin or actin-related proteins are involved in the regulation of nuclear processes such as chromatin remodelling.     

One-sided Tests for Comparing Treatment Effects for Qualitative Data

Various one-sided tests for the comparison of differential treatment effects in two independent groups are developed for qualitative data. This is done for matched and for independent samples, in the case of identical and of different initial distributions. Tests for various kinds of treatment effects are considered. In each case the two observed contingency tables are collapsed into two independent fourfold tables. It is described in which way to select the appropriate procedure for practical problems, and most methods are illustrated in detail by means of a numerical example from clinical psychology.     

Method for electroporation for the early chick embryo

In vitro whole-embryo culture of chick embryos, originally invented by New, has been widely used for studies of early embryogenesis. Here, a method for electroporation using the New culture and its derivatives is described, to achieve misexpression of exogenous gene in a temporally and spatially controlled manner in gastrulating chick embryos. Detailed information for the devices and procedures, and some experimental examples are presented.     

A new approach for anthelmintic discovery for humans

Natural product-based drug discovery has been deemphasized by the pharmaceutical industry. This situation is discordant with the fact that most people in developing countries rely on traditional medicines derived from local biodiversity for healthcare. Despite economic growth in the past 10 years, Africa remains plagued by parasitic infections, out of reach of eradication. Limited regional funding for drug discovery complicates the situation. Novel models are needed to bring sustainability to local drug discovery programs. This Opinion describes an innovative partnership that promotes local leadership to harness a recombinant yeast-based assay to screen for novel anthelmintic candidates in collections of African natural products. Implementation of this strategy in biodiversity-rich but resource-constrained settings can help build sustainable local capacity for drug discovery.     

Potential for improvement by selection for reducing sugar content after cold storage for three potato populations

The objectives of this study were to examine the expected response to selection for reducing-sugar content after cold storage in three hybrid populations, to determine whether these populations included clones low in reducing sugars, and to investigate the effectiveness of indirect selection for chip colour based on selection of sugar content after cold storage. The three hybrid populations included: a random sample of 39 clones of Population 1, which was derived from crossing ND860-2 (a clone low in reducing sugars) with F58089 (a clone intermediate in reducing sugars); 40 clones of Population 2, which was obtained from crossing ND860-2 with Russette (a clone high in reducing sugars); and 40 clones of Population 3, which was derived from crossing Russette with F58089. Sugar content and chip colour were assessed in tubers stored for 2 months at 4 °C at Cambridge, Ontario, and at 3 °C at Benton Ridge, New Brunswick. Population 1 had a slightly greater predicted response to selection for reduction in glucose and total reducing sugars than the other two populations. This could be attributed to higher heritability estimates for Population 1, which was a reflection of smaller clone × environment interaction mean squares. The greater potential advance by selection for fructose, glucose, and total reducing sugars, was a direct consequence of its lower means for these traits. Low reducing-sugar clones were found in all three populations, indicating their potential use for the selection of low reducing sugars. Populations 2 and 3, however, would require stronger selection pressures and, therefore, large population sizes. Expected correlated responses for chip colour by selection for fructose and glucose were similar to, and sometimes exceeded, the expected direct responses in all three populations. Indirect responses for chip colour by selection for sucrose, however, were lower than direct selection responses. These results indicate that indirect selection for chip colour, by selection for either fructose or glucose content after cold storage, is as effective as direct selection for chip colour.     

Dissociation constants for dihydrofolic acid and dihydrobiopterin and implications for mechanistic models for dihydrofolate reductase

The dissociation constants (pKa) for the pteridine ring system of dihydrofolate (H2folate) have been redetermined, and those for dihydrobiopterin (H2biopterin) have been determined. Determination of the pKa for N5 of H2folate is complicated by the low solubility and instability of H2folate at pH 2-4, and other complicating factors. The initial rate of absorbance change due to degradation is a maximum at pH 2.5, and the products depend on the oxygen concentration: under aerobic conditions, (p-aminobenzoyl)glutamic acid and 7,8-dihydropterin-6-carboxaldehyde are major products. H2Biopterin is much more soluble and more stable at low pH. For protonation of N5, the pKa is 2.56 +/- 0.01 for H2biopterin and 2.59 +/- 0.03 for H2folic acid. Spectrophotometric determination of the pKa for the N3-O4 amide group of H2folate is subject to serious errors when a wavelength between 220 and 235 nm is used. These errors arise from the pH-dependent absorbance of mercaptoethanol often present in the preparation. The amide group has a pKa of 10.41 +/- 0.04 in H2biopterin and 10.85 +/- 0.04 in H2folate. The redetermined value for the pKa of N5 of H2folate has implications for mechanistic models for dihydrofolate reductase, and revised kinetic constants have been calculated for one model.     

Competition for water for the food system

Although the global agricultural system will need to provide more food for a growing and wealthier population in decades to come, increasing demands for water and potential impacts of climate change pose threats to food systems. We review the primary threats to agricultural water availability, and model the potential effects of increases in municipal and industrial (M&I) water demands, environmental flow requirements (EFRs) and changing water supplies given climate change. Our models show that, together, these factors cause an 18 per cent reduction in the availability of worldwide water for agriculture by 2050. Meeting EFRs, which can necessitate more than 50 per cent of the mean annual run-off in a basin depending on its hydrograph, presents the single biggest threat to agricultural water availability. Next are increases in M&I demands, which are projected to increase upwards of 200 per cent by 2050 in developing countries with rapidly increasing populations and incomes. Climate change will affect the spatial and temporal distribution of run-off, and thus affect availability from the supply side. The combined effect of these factors can be dramatic in particular hotspots, which include northern Africa, India, China, parts of Europe, the western US and eastern Australia, among others.     

Prospects for biopesticides for aphid control

Diseases form an important component of the natural enemy complex of aphids. The most common and obvious of these diseases are entomophthoran fungi such asErynia neoaphidis Remaudiere & Herbert,Entomophthora planchoniana Cornu,Zoophthora radicans (Brefeld) Batko andConidiobolus obscurus (Hall & Dunn) Remaudiere & Keller. The pest status of some aphids such as the pea aphid,Acyrthosiphon pisum (Harris), is considerably reduced by natural epizootics of fungal disease. However, disease may contribute little to practical control as it is mainly effective in high density populations when weather conditions are suitable. Introduction of exotic diseases for classical biological control is only rarely possible since most diseases, like their aphid hosts, are distributed world-wide. One exception was the successful introduction into Australia of a strain ofZ. radicans for control of spotted alfalfa aphid,Therioaphis trifolii (Monell) f.maculata in 1979. Attempts to manipulate entomophthoran fungi have had limited success because of problems with mass production, the fragility of the conidia and the need for suitably moist conditions. Hyphomycete fungi such asVerticillium lecanii (Zimm.) Viegas,Metarhizium anisopliae (Metsch.) Sorokin,Beauveria bassiana (Bals.) Vuill. andPaecilomyces spp. are more suitable for development as mycoinsecticides as they are cheap to mass produce and form stable conidia. “Vertalec?”, a formulation ofV. lecanii, has been sold in small quantities commercially in Britain and parts of Europe for many years and used mainly in glasshouses. Recently promising results have been obtained with use ofM. anisopliae for control of lettuce root aphid,Pemphigus bursarius (L.) in the UK. Laboratory studies on selected isolates ofB. bassiana andPaecilomyces spp. show a promising level of activity. Problems may occur with these species as they can kill aphid predators such as coccinelids. In addition, more research is needed on developing improved formulations which enable control to be achieved under low humidity conditions.     

Rationale for Leptin-Replacement Therapy for Severe Lipodystrophy

ObjectiveTo review evidence supporting the hypothesis that metabolic manifestations of lipodystrophy result from leptin deficiency and that leptin replacement may be a viable treatment for generalized lipodystrophy.MethodsThis review results from the authors’ collective clinical experience and a comprehensive MEDLINE search of the English-language literature (1998 to 2009) on “leptin and lipodystrophy.”ResultsSevere lipodystrophy syndromes are characterized by loss of subcutaneous adipose tissue and thus a relative deficiency of the adipocyte-secreted hormone leptin. Several small, nonrandomized, open-label trials in a composite total of more than 100 patients with severe lipodystrophy not related to human immunodeficiency virus infection have evaluated the efficacy and safety of recombinant human methionyl leptin (metreleptin) therapy. Variables observed to improve after treatment with metreleptin include glycemic control, insulin sensitivity, plasma triglycerides, caloric intake, liver volume and lipid content, intramyocellular lipid content, and neuroendocrine and immunologic end points. In these studies, metreleptin treatment was well tolerated. Typical daily replacement doses for metreleptin were 0.06 to 0.08 mg/kg for female patients and 0.04 mg/kg for male patients, administered by subcutaneous injection twice daily. Although metreleptin is not yet approved for routine clinical use, it is available by means of expanded access provisions for patients with severe lipodystrophy and associated metabolic abnormalities.ConclusionEvidence published in the medical literature indicates that treating severe lipodystrophy as a leptin deficiency syndrome can improve the metabolic outcomes in affected patients. (Endocr Pract. 2010;16:324-333)     

Relationship Between Competence for Transfection and for Transformation

Deoxyribonucleic acid (DNA) extracted from phage SPP1 is highly infectious on Bacillus subtilis competent cells; the efficiency of infection is 5 x 10(3) to 6 x 10(3) phage equivalents per plaque-forming unit. This DNA was used to study the relationship between competence for transfection and for transformation. The experiments were concerned with the frequency of infection and transformation in mutants exhibiting different levels of competence, the effect of periodate on competence for infection and for transformation, the competition between phage and bacterial DNA, the transformation of cells preinfected with phage DNA, and the infection of cells pretreated with bacterial DNA. The data show that B. subtilis cells competent for transformation are also competent for transfection and vice versa; transfection with phage DNA represents, therefore, a simple way to measure the total number of competent cells in a culture. The fraction of competent cells, determined by SPP1 DNA infection, varied from 10(-2) to 7 x 10(-2).     

Standards for Approval of Hospitals for Graduate Training

The assessment program for approval of hospitals for training in specialties has been augmented by survey visits. Surveyors for the Canadian Council on Hospital Accreditation have acted on behalf of the Royal College of Physicians and Surgeons of Canada and have assisted in the formulation of standard criteria for evaluation of teaching programs. Areas where considerable variation in program exists and where further standardization might profitably be developed are suggested. It is recommended that periodic on-the-site visits be made to all specialty training hospitals. Standards should be further elucidated to guide teachers, students and Royal College surveyors alike. It is emphasized that standards cannot be used to assess the calibre of teaching and learning, but can be employed to assist in evaluating the teachings and learning media that are likely to produce good (or poor) results.     

Plasmid vector for cloning in Streptococcus pneumoniae and strategies for enrichment for recombinant plasmids

A new plasmid, pLS101, was constructed for use as a vector for cloning in Streptococcus pneumoniae. This plasmid carries two selectable genes, tet and malM, each of which contains two or more restriction sites for cloning. Insertional inactivation of the malM gene allowed direct selection of TcRMal- clones containing recombinant plasmids. Other means of enriching a recipient population for cells containing recombinant plasmids were examined. The effect of removing vector terminal phosphate in attempts to clone heterogeneous DNA fragments, such as those from chromosomal DNA, was to abolish recombinant plasmid establishment altogether, presumably because donor DNA processing during entry into the cell prevented establishment of the hemiligated molecule. However, with homogeneous DNA fragments, such as those from plasmid or viral DNA, vector phosphate removal allowed enrichment for recombinant plasmids. In the cloning of heterogeneous DNA that was homologous to the recipient chromosome (i.e. chromosomal DNA from S. pneumoniae), recovery of recombinant plasmids could be enriched tenfold (relative to the regenerated vector) by the process of chromosomal facilitation of plasmid establishment. This involved an additional passage of the mixed plasmids in which interaction with the chromosome of plasmids containing chromosomal DNA inserts (i.e. recombinant plasmids) increased their frequency of establishment relative to the vector plasmid. An overall strategy for cloning in S. pneumoniae, depending on the nature of the fragment to be cloned, is proposed.     

Protocol for sampling environmental sites for legionellae

A protocol for sampling environmental sites was developed and used to identify possible sources of Legionella species in support of epidemiologic investigations at two hospitals. In hospital A, legionellae were isolated from 43 of 106 (40%) different sites. Three separate Legionella pneumophila serotypes and a previously unrecognized species were present in different combinations in the positive samples. Two of five cooling towers contained the same L. pneumophila serogroup 1 monoclonal type (1,2,4,5) as was isolated from patients. The same monoclonal type was also isolated from make-up water for the two cooling towers, a hot water tank, water separators in four main air compressor systems for respiratory therapy, and cold and hot water faucets. In hospital B, 13 of 37 (38%) sample sites contained legionellae, all of which were L. pneumophila serogroup 1. The monoclonal type matching isolates from patients (1,2,4,5) was found at the highest concentration in a hot water tank, but it was also present at four other sample sites. Since legionellae not related to disease may be found in many of the sites sampled, an epidemiologic association with the probable source should be established before intervention methods, such as disinfection, are undertaken.     

Current strategies for identifying and validating targets for new treatment-shortening drugs for TB

There is an urgent need for new drugs to treat tuberculosis. During the last forty years the only drugs to have been developed are variations on existing ones, but new drug candidates must offer improvements over existing agents. In particular, we require new drugs having novel mechanisms of action that are active against drug-resistant strains and also kill persistent bacilli, thus shortening the length of chemotherapy. Recent advances in our understanding of the biology of Mycobacterium tuberculosis, in particularly the availability of the genome sequence coupled with development of new genetic tools, have greatly contributed to the discovery of potential drug targets for new antituberculars. However, although many potential new drug targets have been identified, greater effort is required in target validation to show properly that they are essential for bacterial growth and survival. In this review, the current drug development pipeline and the strategies employed to identify and validate novel tuberculosis drug targets are presented.