Comparison of four erythrocyte fragility tests as indicators of vitamin E status in adult dogs.

Plasma alpha-tocopherol (alpha-T) concentrations, erythrocyte osmotic fragility and detergent sensitivity were measured at 8 week intervals in two 1-year-old male beagle dogs fed a vitamin E-deficient diet (< 0.08 mg per kg alpha-T) and in two control beagles fed the same diet supplemented with vitamin E (> 90 mg per kg alpha-T). Beginning at 24 weeks, dialuric acid haemolysis and spontaneous haemolysis were evaluated also. In the vitamin E-deficient dogs, plasma alpha-T concentrations declined progressively from baseline values of 20.5 and 31.3 micrograms per ml to 0.11 and 0.07 micrograms per ml, respectively, by 90 weeks. The supplemented dogs maintained alpha-T concentrations between 18.3 and 38.4 micrograms per ml. Both dialuric acid haemolysis (R = -0.89) and spontaneous haemolysis (R = -0.91) increased with declining plasma alpha-T concentration. In the dialuric acid haemolysis assay, 50 per cent haemolysis occurred when plasma alpha-T declined to 1.7 micrograms per ml, compared with spontaneous haemolysis in which 50 per cent haemolysis occurred when plasma alpha-T declined to 0.5 micrograms per ml. Osmotic fragility and detergent sensitivity remained unchanged in the vitamin E-deficient dogs throughout the study. Of the four tests, dialuric acid haemolysis was the most sensitive in-vitro assay for vitamin E deficiency in adult dogs.     

A study of the presentation of somatic symptoms in general practice by patients with psychiatric disturbance.

A computerized questionnaire was used to collect information on the presentation of symptoms in all 125 new patients presenting to one general practitioner in the course of one year who were considered to be suffering clinically significant psychiatric disturbance. Comparison was made between the 73 (58%) patients presenting with psychological symptoms and the 52 (42%) patients presenting with somatic symptoms for which no physical explanation was evident at the time of the consultation. Important differences emerged between the groups. Those patients presenting somatic symptoms had lower scores on the tests of psychiatric distress (indicating severity), fewer individual symptoms and fewer severe symptoms than patients presenting with psychological problems. This group also had statistically significant differences in personality profile and reported significantly fewer social problems. Prognosis for both groups was similar in that patients in both groups were equally likely to have a normal psychiatric distress score after six months. Adequate management of somatizing patients calls for vigilance and for improved detection and negotiating skills. Reviewing the computer results with patients helped them discuss their symptoms and the system allowed the general practitioner not only a clinical assessment of these patients' problems but a measure of psychological, social and personality components.     

Effects of recombination rate and gene density on transposable element distributions in Arabidopsis thaliana

Transposable elements (TEs) comprise a major component of eukaryotic genomes, and exhibit striking deviations from random distribution across the genomes studied, including humans, flies, nematodes, and plants. Although considerable progress has been made in documenting these patterns, the causes are subject to debate. Here, we use the genome sequence of Arabidopsis thaliana to test for the importance of competing models of natural selection against TE insertions. We show that, despite TE accumulation near the centromeres, recombination does not generally correlate with TE abundance, suggesting that selection against ectopic recombination does not influence TE distribution in A. thaliana. In contrast, a consistent negative correlation between gene density and TE abundance, and a strong under-representation of TE insertions in introns suggest that selection against TE disruption of gene expression is playing a more important role in A. thaliana. High rates of self-fertilization may reduce the importance of recombination rate in genome structuring in inbreeding organisms such as A. thaliana and Caenorhabditis elegans.     

Measurement of human cytomegalovirus loads by quantitative real-time PCR for monitoring clinical intervention in transplant recipients

Quantitative monitoring of human cytomegalovirus (HCMV) infection is helpful in determining appropriate antiviral management of transplant recipients. Quantitative PCR technologies have demonstrated accuracy in measuring systemic HCMV loads. A total of 298 consecutive whole-blood specimens submitted to the Clinical Virology Laboratory at Vanderbilt University Medical Center from 15 February to 31 October 1999 were included in the study. In addition to a qualitative colorimetric microtiter plate PCR assay (MTP-PCR) and a semiquantitative pp65 antigenemia assay, each specimen was measured for HCMV loads by a quantitative PCR assay performed on an ABI PRISM 7700 Sequence Detection System (TaqMan). Compared to results of the MTP-PCR, the sensitivity, specificity, positive predictive value, and negative predictive value were 70.5, 97.5, 87.8, and 92.8% for the antigenemia assay and were 96.7, 92.0, 75.6, and 99.1% for the TaqMan assay, respectively. There was a high correlation between antigenemia values and HCMV loads as determined by the TaqMan (r = 0.989; P < 0.001). Antigenemia values of 0, 1 to 10, 11 to 100, 101 to 1,000, and over 1,000 positive cells per 2 x 10(5) leukocytes corresponded to median HCMV loads measured by TaqMan of 125, 1,593, 5,713, 16,825, and 5,425,000 copies/ml, respectively. Corresponding to antigenemia values of 1 to 2, 10, and 50 positive cells per 2 x 10(5) leukocytes, HCMV viral loads of 1,000, 4,000, and 10,000 copies/ml are proposed as cutoff points for initiating antiviral therapy in patient groups with high, intermediate, and low risk of CMV diseases.     

Burkitt's lymphomas express VH genes with a moderate number of antigen-selected somatic mutations.

The normal counterpart of the neoplastic B cells occurring in Burkitt's lymphomas (BL) is an issue of controversial debate. To clarify this matter, a semi-nested primer polymerase chain reaction was performed to amplify the VDJ rearrangements of the immunoglobulin heavy chain (VH) gene of DNA extracts from 10 (8 sporadic and 2 endemic) BL cases. The resulting amplificates were sequenced for comparison with known germ line VH segments. The control cases comprised six cases of B cell chronic lymphocytic leukemia and six cases of mantle cell lymphoma known to display naive nonmutated, ie, pre-germinal center VH configurations; and eight cases of follicular center lymphoma known to display mutated VH genes with signs of a still-ongoing mutation reaction, characteristic for germinal center cells and lymphomas that derive therefrom. The results of this approach revealed that both sporadic and endemic BL express mutated VH genes with a mutation frequency considerably lower (4.9% and 5.4%, respectively) than that observed in follicular center lymphoma (11.8%). In addition, after subcloning the amplificates, sequence analysis revealed no signs of ongoing mutations. These results led us to conclude that the derivation of neoplastic B cells in BL is definitely not from naive, nonmutated pre-germinal center B cells. Instead, our findings support the view that BL cells stem either from early centroblasts that are arrested after an initial hypermutation reaction, or from germinal center B cells that have differentiated in terms of surface immunoglobulin profile and mutation pattern but not in terms of morphology and proliferation toward SIgM+ IgD- memory B cells because of the deregulated c-myc gene expression.     

Monoclonal antibody to desmosomal glycoprotein 1--a new epithelial marker for diagnostic pathology

Desmosomes are intercellular adhesive junctions that occur in almost all epithelia and should therefore be useful as epithelial markers in tumour diagnosis. Here, we describe a monoclonal antibody, 32-2B, to a major desmosomal glycoprotein (dgl) which reacts with human tissues in paraffin sections. This antibody was tested for its ability to stain epithelia and tumours. It reacted with all epithelia tested and with every specimen of a wide range of carcinomas. It also stained meningiomas, another desmosome-containing tumour. It did not stain other types of tumours including lymphomas, melanomas, and various sarcomas, or normal tissues which lack desmosomes. These characteristics demonstrate that 32-2B is a reliable epithelial marker that may have a useful role in diagnostic histopathology.     

An introduction to stem cells

1998 saw the publication of two papers describing the growth in vitro of human embryonic stem (ES) cells derived either from the inner cell mass (ICM) of the early blastocyst or the primitive gonadal regions of early aborted fetuses. Work on murine ES cells over many years had already established the amazing flexibility of ES cells, essentially able to differentiate into almost all cells that arise from the three germ layers. The realization of such pluripotentiality (see below) has, of course, resulted in the field of stem cell research going into overdrive, the establishment of many new biotechnology companies (http://www.stemcellresearchnew.com/catalog1677.html), and a genuine belief that stem cell research will deliver a revolution in terms of how we treat cardiovascular disease, neurodegenerative disease, cancer, diabetes, and the like. However, many people believe that early human embryos should be accorded the same status as any sentient being and thus their 'harvesting' for stem cells is morally unjustifiable. With this in mind, other sources of malleable stem cells have been sought. In the adult, organ formation and regeneration was thought to occur through the action of organ- or tissue-restricted stem cells (i.e. haematopoietic stem cells giving rise to all the cells of the blood, neural stem cells making neurons, astrocytes, and oligodendrocytes). However, it is now believed that stem cells from one organ system, for example the haematopoietic compartment can develop into the differentiated cells within another organ system, such as the liver, brain or kidney. Thus, certain adult stem cells may turn out be as malleable as ES cells and so also be useful in regenerative medicine. This brief overview summarizes the important attributes of tissue-based stem cells and clarifies the terms used.