Statistical estimation of the precision of clinico-laboratory measurements

Traditionally, the term "precision" denotes the quality of work, uniting the correctness and reproducibility of results. However, it can have another sense: the minimal difference between the specimens, detectable by this or that device or method. In order to rule out misunderstanding, we propose to use the term "measuring precision", if the term is used in its second meaning. It is easy to assess the measuring precision by statistical processing of large scope of data: if the histogram shows waves which disappear after the histogram step is increased, this means that the device and method used in this study permit biochemical analysis only at measuring precision corresponding to the histogram step at which the waves disappear. A table of measuring precision values is offered for 19 methods realized using the Labsystems FP-900 device (Finland) In many cases it is obviously low.     

Regulation of organelle movement in melanophores by protein kinase A (PKA), protein kinase C (PKC), and protein phosphatase 2A (PP2A)

We used melanophores, cells specialized for regulated organelle transport, to study signaling pathways involved in the regulation of transport. We transfected immortalized Xenopus melanophores with plasmids encoding epitope-tagged inhibitors of protein phosphatases and protein kinases or control plasmids encoding inactive analogues of these inhibitors. Expression of a recombinant inhibitor of protein kinase A (PKA) results in spontaneous pigment aggregation. alpha-Melanocyte-stimulating hormone (MSH), a stimulus which increases intracellular cAMP, cannot disperse pigment in these cells. However, melanosomes in these cells can be partially dispersed by PMA, an activator of protein kinase C (PKC). When a recombinant inhibitor of PKC is expressed in melanophores, PMA-induced pigment dispersion is inhibited, but not dispersion induced by MSH. We conclude that PKA and PKC activate two different pathways for melanosome dispersion. When melanophores express the small t antigen of SV-40 virus, a specific inhibitor of protein phosphatase 2A (PP2A), aggregation is completely prevented. Conversely, overexpression of PP2A inhibits pigment dispersion by MSH. Inhibitors of protein phosphatase 1 and protein phosphatase 2B (PP2B) do not affect pigment movement. Therefore, melanosome aggregation is mediated by PP2A.     

An epidemiologic, clinical, and therapeutic study of childhood Guillain-Barré syndrome in Kuwait: is it related to the oral polio vaccine?

We studied Guillain-Barré syndrome, affecting children 12 years old or less, throughout Kuwait, in the period between January 1, 1992, and March 31, 1997. Nineteen children had the diagnostic criteria of Guillain-Barré syndrome, with an overall annual incidence rate of 0.95/100,000 population at risk. Female patients outnumbered male patients with a sex ratio of 1.4:1. There was a clustering of cases in winter and spring and in the year 1996. The disease symptoms were relatively severe in our patients because only 16% (3 of 19) of them were able to walk at the height of their illness, whereas the rest were bed or chair bound or needed assisted ventilation. Two patients had the electrodiagnostic features of axonal neuropathy and both had residual deficits on follow-up, whereas the rest recovered fully. All the patients received intravenous immunoglobulin. The mean time to walk unaided was 23.5 days (range, 2-84 days) after intravenous immunoglobulin and excluding the two patients with axonal neuropathy, and full recovery was achieved in a mean time of 103 days (range, 30-300 days). Contrary to previous studies, we found no correlation between oral polio vaccine administration and Guillain-Barré syndrome in 2 successive years (1995 and 1996) during a nationwide campaign targeting children less than 5 years old.     

Plasma lipids, HDL and apolipoproteins, and coronary heart disease in men less than 50 years old. A case-control study

Therapeutic interventions in the skeletal system are an essential part of interventional radiology. Although in terms of figures these procedures are applied less frequently, they are very effective. Percutaneous transarterial embolization of a spinal tumor is well-established interventional treatment. It is primary treatment for preoperative devascularization, but also for palliation of pain and for reduction of tumor volume. As an alternative access for embolization, direct percutaneous puncture of a vertebra is used. A new and promising technique is vertebroplasty, the percutaneous injection of acrylic surgical cement in destroyed vertebrae. The present paper discusses indications, technique, results and complications of these interventional therapeutic modalities in the treatment of primary and secondary spinal tumors.     

Feldkamp and circle-and-line cone-beam reconstruction for 3D micro-CT of vascular networks

Detailed morphometric knowledge of the microvascular network is needed for studies relating structure to haemodynamic function in organs like the lung. Clinical volumetric CT is limited to millimetre-order spatial resolution. Since evidence suggests that small arterioles (50 to 300 micrometres) dominate pulmonary haemodynamics, we built a micro-CT scanner, capable of imaging excised lungs in 3D with 100 microm resolution, for basic physiology research. The scanner incorporates a micro-focal (3 microm) x-ray source, an xyz theta stage and a CCD-coupled image intensifier detector. We imaged phantoms and contrast-enhanced rat lungs, reconstructing the data with either the Feldkamp or the circle-and-line cone-beam reconstruction algorithm. We present reconstructions using 180 views over 360 degrees for the circular trajectory, augmented with views from a linear scan for the circle-and-line algorithm. Especially for platelike features perpendicular to the rotation axis and remote from the midplane, the circle-and-line algorithm produces superior reconstructions compared with Feldkamp's algorithm. We conclude that the use of nonplanar source trajectories to perform micro-CT on contrast-enhanced, excised lungs can provide data useful for morphometric analysis of vascular trees, currently down to the 130 microm level.     

Systematic screening of the LDL-PLA2 gene for polymorphic variants and case-control analysis in schizophrenia

Systematic scans of the genome using microsatellite markers have identified chromosome 6p21.1 as a putative locus for schizophrenia in multiply affected families. There is also evidence from a series of studies for a role of abnormal phospholipid metabolism in schizophrenia. In light of these findings, and the role of platelet activating factor in neurotransmission and neurodevelopment, we have examined the LDL-PLA2 (plasma PAF acetylhydrolase, PAF-AH) gene, a serine dependent phospholipase that has been mapped by hybrid mapping to chromosome 6p21.1, as a positional candidate gene for schizophrenia. The gene was systematically screened using SSCP/HD analysis for polymorphisms associated with the disease. Four polymorphic variants were found within the gene and studied in a group of 200 schizophrenic patients and 100 controls. The variant in exon 7 (Iso195Thr) was found to be weakly associated with schizophrenia (p = 0.04) and the variant in exon 11 (Val379Ala) almost reached significance (p = 0.057). After correcting for multiple testing no significant associations were detected. Haplotype analysis combining pairs of polymorphisms also provided no evidence for association of this gene with schizophrenia in our sample of patients.     

Aging and the dendritic morphology of the rat laterodorsal and pedunculopontine tegmental nuclei

This study is based on interviews with 37 persons fulfilling the DSM-IV criteria for kleptomania recruited through newspaper advertisements, and on 50 shoplifters interviewed directly after apprehension. Our hypothesis was that there are no absolute borders between 'pure' kleptomania according to DSM-IV and other forms of shoplifting. When asked about the latest case of shoplifting, one fifth of the shoplifters reported not having stolen the item for personal use and had later discarded it. A quarter of the kleptomaniacs reported ambivalence when asked if they needed the item in question. The degree of reported impulsivity and a feeling of not being oneself at the time of the theft was the same in the two groups. The two groups also estimated their degree of impulsivity, planning, thrill, relief, vengeance, need, pleasure on a Visual Analogue Scale (VAS) as well as the degree of psychiatric imbalance on the latest theft occasion. These estimates showed that there were no differences between the groups concerning the degree of planning, psychological imbalance and the need for the stolen item in question. The kleptomaniacs rated a feeling of inner tension before the theft higher than the shoplifters. The same was true concerning a feeling of relief during the theft and impulsivity. However, the shoplifters also rated high on all these items. Altogether, these findings support our hypothesis that many shoplifters, even if they do not fulfill all DSM criteria for kleptomania, may constitute a significant medical problem and should be offered support and treatment. Anti-depressants as well as the educational programmes developed by the Shoplifters Alternatives may be effective not only in cases of kleptomania but also for more unselected groups of non-professional shoplifters.     

The effect of the lectin from Sambucus nigra inflorescences on spontaneous and alkylating agent-induced mutagenesis in mammalian somatic cells

Data on separation of purified galactose-specific lectin as well as its two polypeptide chains from inflorescences of European elder Sambucus nigra are represented. Their molecule quaternary structure after the pattern a2 b2 is suggested. It was shown that purified protein in concentration 2.0 mg/ml had mutagenic activity and might enhance mutagenic effect of alkylating substance MNNG. Thus, preparations of lectin from inflorescences of European elder influenced on spontaneous and induced by the alkylating agent mutagenicity in mammalian somatic cells in vitro.