Correlation of hyperforin content of Hypericum perforatum (St John's Wort) extracts with their effects on alcohol drinking in C57BL/6J mice: a preliminary study

Extracts of the herb St John's Wort have been shown to reduce alcohol intake in alcohol-preferring rats, but it is not known which of the constituent(s) are responsible for this effect. In this study, the effect of a crude methanolic extract of Hypericum perforatum (negligible hyperforin content) on alcohol drinking in C57BL/6J alcohol-preferring mice was compared with that of a hyperforin-rich extract (45% hyperforin) prepared by extracting the herb with supercritical carbon dioxide. The dose of the hyperforin-rich extract required to significantly reduce 10% ethanol intake (5 mg/kg) was 125-fold less than that required for the crude extract (625 mg/kg), and was comparable to the dose of fluoxetine (10 mg/kg) required to produce a similar effect. None of these agents significantly affected water intake. These results suggest that the effects of H. perforatum extracts on alcohol drinking behaviour are due to the hyperforin content of the herb rather than to other, more polar constituents. Hyperforin is an unstable compound and this study also highlights the effect of different methods of extract preparation on hyperforin content.

Haematological safety of antipsychotic drugs

Haematological abnormalities are frequently encountered during treatment with antipsychotic drugs. Most of these are mild and of no clinical significance. In the case of many, there is often difficulty in establishing a cause-and-effect relationship between the drug and the abnormality. However, in a small minority of patients, hazardous, potentially life-threatening haematological effects can occur due to a combination of pharmacological and host factors. These include leucopenia and agranulocytosis. Although such effects are rare, it is essential that they are diagnosed and managed promptly. In this paper, the authors review the haematological adverse effects and safety of antipsychotic drugs and present a strategy for prevention.

Structural insights into the evolution of the pantothenate-biosynthesis pathway

Pantothenate is synthesized in bacteria, fungi and plants, and as vitamin B5 is a dietary requirement in animals. The three-dimensional structures of the four Escherichia coli enzymes involved in the production of pantothenate have been determined. We describe the use of comparative analyses of the sequences and structures to identify distant homologues of the four enzymes in an attempt to understand the evolution of the pathway. We conclude that it is likely to have evolved via a patchwork mechanism, whereby the individual enzymes were recruited separately.

Cancer-related fatigue--a difference of opinion? Results of a multicentre survey of healthcare professionals, patients and caregivers

The objective of this study was to investigate the perceptions of patients with cancer, their caregivers and healthcare professionals (HCPs) about fatigue and its impact on quality of life. It was a cross-sectional survey, the respondents were patients with cancer attending three UK regional cancer centres (n = 1,370), their informal caregivers (n = 1,370) and a random selection of HCPs (oncologists/nurses/radiographers/haematologists; n = 1,098). The response rates for patients, caregivers and HCPs were 42%, 33% and 34% respectively. Fatigue was reported to affect 56% of patients and to have a considerable impact on quality of life. Caregivers also recognized that fatigue was a common problem, with significant effects on patients' quality of life and impact on themselves. Healthcare professionals recognized that fatigue was a common problem for their patients but overestimated its impact on some aspects of patients' daily lives. Although most HCPs reported that they prescribed/recommended treatment for over half of their patients, only 14% of patients reported receiving any such treatment. The most common advice was to take more rest and relaxation.

CONCLUSIONS

patients with cancer report that fatigue is a common and distressing symptom and the importance of this symptom is generally recognized by both HCPs and lay-carers. Healthcare professionals need more information about the effectiveness of existing interventions for cancer-related fatigue and further research is required to improve the current management of this debilitating symptom.

Neural differentiation of mouse embryonic stem cells

Pluripotent embryonic stem cells can give rise to neuroectodermal derivatives in culture. This potential could be harnessed to generate neurons and glia for cell-replacement therapies in the central nervous system and for use in drug discovery. However, current methods of neural differentiation are empirical and relatively inefficient. Here, we review these methodologies and present new tools for quantification, analysis and manipulation of embryonic stem cell neural determination.

Rapid loss of Oct-4 and pluripotency in cultured rodent blastocysts and derivative cell lines

The POU transcription factor Oct-4 is essential for the pluripotent character of the mouse inner cell mass (ICM) and derivative embryonic stem (ES) cells. We analyzed the expression of Oct-4 during culture and establishment of cell lines from mouse and rat preimplantation embryos. Oct-4 was rapidly lost in primary outgrowths of the majority of cultured embryos prior to any evidence of morphological differentiation. Oct-4 persisted in only a minority of strain 129 cultures, which can go on to give ES cells. We used transgenic rats in which the dual reporter/selection marker beta-geo is under control of Oct-4 regulatory elements to investigate the effect of direct selection for Oct-4 expressing cells. Ablation of all cells occurred, consistent with complete downregulation of Oct-4. Without selection, in contrast, continuous cultures of morphologically undifferentiated cells could be derived readily from rat blastocysts and ICMs. However, these cells did not express significant Oct-4 and, although capable of differentiating into extraembryonic cell types, appeared incapable of producing fetal germ layer derivatives. Downregulation of Oct-4 appears to be a limiting factor in attempts to derive pluripotent cell lines from preimplantation embryos.

Non-melanoma skin cancer risk in the Queensland renal transplant population

BACKGROUND

Non-melanoma skin cancer (NMSC) is an important complication of solid organ transplantation, especially in areas of high ultraviolet light exposure. Registry data may underestimate the scale of the problem.

OBJECTIVES

A single-observer study of a Queensland renal transplant population was conducted between July 1999 and April 2000 utilizing both cross-sectional and retrospective data. The aims were to determine accurately the risk of NMSC following renal transplantation and compare this with currently available registry data.

PATIENTS AND METHODS

A structured interview and full skin examination was completed by 398 renal transplant recipients. Case notes and histology reports were examined for details of previous skin tumours. Independently collected data on 341 subjects from the Australia and New Zealand Dialysis and Transplantation Registry (ANZDATA) were also examined.

RESULTS

One hundred and eighty-seven of 361 (51.8%) transplant recipients of Fitzpatrick skin types I-IV had developed 3979 histologically diagnosed NMSCs since first transplantation. The ratio of SCC/BCC was reversed from 1 : 3.7 before transplantation to 2 : 1 after transplantation. NMSC increased with duration of immunosuppression; 29.1%, 52.2%, 72.4% and 82.1% of those immunosuppressed for < 5, 5-10, 10-20 and > 20 years, respectively, had developed at least one tumour. The ANZDATA registry under-recorded the numbers of patients with NMSC by 28.4% and gave no indication of tumour numbers.

CONCLUSIONS

NMSC is a greater clinical problem in renal transplant recipients living in subtropical Queensland, Australia, than is shown by currently available registry data. This has implications for the development of prevention and surveillance strategies.

Organochlorine chemicals in seafood: occurrence and health concerns

The cheap availability of chlorine gas, together with the development of industrial chlorinating procedures in the 20th century, led to the production of a wide range of organochlorine compounds many with a variety of commercial applications, including usage as insecticides and defoliants and polychlorinated biphenyls (PCBs) used as coolants in electricity supply transformers. However, it was soon found that many of these technologically valuable chemicals suffered from a major disadvantage in that they resisted biodegradation and that the continued use of these compounds would lead to their persistence and accumulation in the environment and thus enter the human food chain. Despite regulatory bans or strict limits on usage being imposed on organochlorine pesticides in most countries, these compounds continue to be detected in measurable amounts in the eco-system including marine life. In general, organochlorine levels in fish intended for human consumption are low and probably below levels likely to adversely affect human health. Populations at higher risk than most people are those subsisting largely on fish and other marine life. Additionally, fish oils obtained from contaminated fish, if consumed in substantial quantities by infants and young children, might present potential health problems if levels are not continually regulated. Behavioral and neurological effects have been reported in children and ascribed to the consumption of PCB contaminated diet including fish. Another current major human health concern, yet to be resolved, about organochlorine contaminants in the human diet relates to the potential ability of many of these chemicals at low doses to act as "endocrine disruptors".

The importance of full participation: lessons from a national case-control study

Differential participation between cases and controls can lead to biased estimates of risk. However, the effects of participation are often ignored. We report a detailed analysis of locations of residence for participants and non-participants in a large, national case-control study of childhood cancer in Great Britain, using the 1991 census. The initial selection of 7669 controls, taken from lists of those registered with a General Practitioner, was representative of the British population in respect to an areal-based index of material deprivation. However, parents of controls agreeing to participate were living in more affluent areas than initially selected controls and their matched 3838 cases. The three components of the deprivation index, persons unemployed, households not owning a car or their home were similarly associated with participation. Other census characteristics, such as proportion of flat dwellers and centrally heated households were also associated with control participation. Population density of the local area was not different between participating controls and their matched cases. However, initially selected controls lived in more urban areas than their cases. Such differences are not unique to this study, as they are an inevitable consequence of incomplete participation. The implications of these differences are discussed, in relation to the difficulty this imposes in the interpretation of studies of disease aetiology.

Embryo-derived stem cells: of mice and men

Mouse embryonic stem cells are continuous cell lines derived directly from the fetal founder tissue of the preimplantation embryo. They can be expanded in culture while retaining the functional attributes of pluripotent early embryo cells. In particular, they can participate fully in fetal development when reintroduced into the embryo. The capacity for multilineage differentiation is reproduced in culture where embryonic stem cells can produce a wide range of well-defined cell types. This has stimulated interest in the isolation of analogous cells of human origin. Such human pluripotent stem cells could constitute a renewable source of more differentiated cells that could be employed to replace diseased or damaged tissue by cellular transplantation. In this review, the relationships between mouse embryonic stem cells, resident pluripotent cells in the embryo, and human embryo-derived cell lines are evaluated, and the prospects and challenges of embryo stem cell research are considered.

The human melanocortin-1 receptor locus: analysis of transcription unit, locus polymorphism and haplotype evolution

The complete sequence of the MC1R locus has been assembled, the coding region of the gene is intronless and placed within a 12 kb region flanked by the NULP1 and TUBB4 genes. The immediate promoter region has an E-box site with homology to the M-box consensus known to bind the microphthalmia transcription factor (MITF); however, promoter deletion analysis and transactivation studies have failed to show activation through this element by MITF. Polymorphism within the coding region, immediate 5' promoter region and a variable number tandem repeat (VNTR) minisatellite within the locus have been examined in a collection of Caucasian families and African individuals. Haplotype analysis shows linkage disequilibrium between the VNTR and MC1R coding region red hair variant alleles which can be used to estimate the age of these missense changes. Assuming a mean VNTR mutation rate of 1% and a star phylogeny, we estimate the Arg151Cys variant arose 7500 years before the present day, suggesting these variants may have arisen in the Caucasian population more recently than previously thought.

Crystal structure of Escherichia coli ketopantoate reductase at 1.7 A resolution and insight into the enzyme mechanism

Ketopantoate reductase (KPR, EC 1.1.1.169) catalyzes the NADPH-dependent reduction of ketopantoate to pantoate on the pantothenate (vitamin B(5)) biosynthetic pathway. The Escherichia coli panE gene encoding KPR was cloned and expressed at high levels as the native and selenomethionine-substituted (SeMet) proteins. Both native and SeMet recombinant proteins were purified by three chromatographic steps, to yield pure proteins. The wild-type enzyme was found to have a K(M)(NADPH) of 20 microM, a K(M)(ketopantoate) of 60 microM, and a k(cat) of 40 s(-1). Regular prismatic KPR crystals were prepared using the hanging drop technique. They belonged to the tetragonal space group P4(2)2(1)2, with cell parameters: a = b = 103.7 A and c = 55.7 A, accommodating one enzyme molecule per asymmetric unit. The structure of KPR was determined by the multiwavelength anomalous dispersion method using the SeMet protein, for which data were collected to 2.3 A resolution. The native data were collected to 1.7 A resolution and used to refine the final structure. The secondary structure comprises 12 alpha-helices, three 3(10)-helices, and 11 beta-strands. The enzyme is monomeric and has two domains separated by a cleft. The N-terminal domain has an alphabeta-fold of the Rossmann type. The C-terminal domain (residues 170-291) is composed of eight alpha-helices. KPR is shown to be a member of the 6-phosphogluconate dehydrogenase C-terminal domain-like superfamily. A model for the ternary enzyme-NADPH-ketopantoate ternary complex provides a rationale for kinetic data reported for specific site-directed mutants.

Epidermal nerve innervation in impaired glucose tolerance and diabetes-associated neuropathy

The authors describe skin biopsy findings in patients with peripheral neuropathy associated with diabetes and impaired glucose tolerance (IGT). Six patients with IGT, eight with early diabetes-associated neuropathy, and five controls were recruited. Most subjects underwent nerve conduction studies (NCS) and quantitative sensory tests (QST). Skin biopsy was abnormal in all neuropathy subjects and correlated poorly with NCS. Neuropathy associated with IGT primarily affects small fibers and is similar to early diabetes-associated neuropathy.

The crystal structure of E. coli pantothenate synthetase confirms it as a member of the cytidylyltransferase superfamily

BACKGROUND

Pantothenate synthetase (EC 6.3.2.1) is the last enzyme of the pathway of pantothenate (vitamin B(5)) synthesis. It catalyzes the condensation of pantoate with beta-alanine in an ATP-dependent reaction.

RESULTS

We describe the overexpression, purification, and crystal structure of recombinant pantothenate synthetase from E. coli. The structure was solved by a selenomethionine multiwavelength anomalous dispersion experiment and refined against native data to a final R(cryst) of 22.6% (R(free) = 24.9%) at 1.7 A resolution. The enzyme is dimeric, with two well-defined domains per protomer: the N-terminal domain, a Rossmann fold, contains the active site cavity, with the C-terminal domain forming a hinged lid.

CONCLUSIONS

The N-terminal domain is structurally very similar to class I aminoacyl-tRNA synthetases and is thus a member of the cytidylyltransferase superfamily. This relationship has been used to suggest the location of the ATP and pantoate binding sites and the nature of hinge bending that leads to the ternary enzyme-pantoate-ATP complex.

Susceptibility and modifier genes in cutaneous basal cell carcinomas and their associations with clinical phenotype

While ultraviolet radiation (UV) is critical in the pathogenesis of basal cell carcinomas (BCC), its role in determining the phenotypic variation shown by patients is unknown. Thus, patients manifest variation in BCC numbers, patterns of presentation and tumour site. We have used this diversity to classify patients into subgroups that are associated with different risks of developing tumours. Two phenotypes are particularly interesting. Firstly, presentation with clusters of BCC. These patients, termed multiple presentation phenotype (MPP), had two to five BCC at one presentation, suggesting rapid accrual over short periods of time. They comprised 15% of our 1200 BCC patients. A minority of patients demonstrated multiple clustering events, a phenomenon that is associated with a genetic pre-disposition. The second risk phenotype, characterised by tumours on the trunk, is also associated with a pre-disposition. Both phenotypes were characterised by a susceptibility to develop numerous BCC. Thus, all our patients with more than five BCC had one or both of these phenotypes. We are using a candidate gene approach to identify loci associated with risk of these phenotypes (susceptibility genes) and tumour numbers in them (modifier genes). Interestingly, we did not identify differences in UV exposure between patients with high- and low-risk phenotypes.

Identification of Tyr58 as the proton donor in the aspartate-alpha-decarboxylase reaction

The decarboxylation of L-aspartate by E. coli L-aspartate-alpha-decarboxylase (ADC) is shown to occur with retention of configuration; analysis of the protein structure identifies Tyr58 as the proton donor in the decarboxylation mechanism.

Attempts to improve treatment outcomes in acute myeloid leukemia (AML) in older patients: the results of the United Kingdom Medical Research Council AML11 trial

In an attempt to improve induction chemotherapy for older patients with acute myeloid leukemia (AML),1314 patients were randomized to 1 of 3 induction treatments for 2 courses of DAT (daunorubicin, cytarabine, and thioguanine) 3 + 10, ADE (daunorubicin, cytarabine, and etoposide) 10 + 3 + 5, or MAC (mitoxantrone-cytarabine). The remission rate in the DAT arm was significantly better than ADE (62% vs 50%; P =.002) or MAC (62% vs 55%; P =.04). This benefit was seen in patients younger and older than 70 years. There were no differences between the induction schedules with respect to overall survival at 5 years (12% vs 8% vs 10%). A total of 226 patients were randomized to receive granulocyte colony-stimulating factor (G-CSF) or placebo as supportive care from day 8 after the end of treatment course 1. The remission rate or survival were not improved by G-CSF, although the median number of days to recover neutrophils to 1.0 x 10(9)/L was reduced by 5 days. Patients who entered remission (n = 371) were randomized to stop after a third course (DAT 2 + 7) or after 6 courses, ie, a subsequent COAP (cyclophosphamide, vincristine, cytarabine, and prednisolone), DAT 2 + 5, and COAP. The relapse risk (81% vs 73%), disease-free survival (16% vs 23%), and overall survival at 5 years (23% vs 22%) did not differ between the 3-course or 6-course arms. In addition to a treatment duration randomization, 362 patients were randomized to receive 12-month maintenance treatment with low-dose interferon, but no benefit was seen with respect to relapse risk, disease-free survival, or overall survival.