Hazards of non coherent light sources as determined by the framework of IEC TR-60825-9

An overview is provided of the scope and application of IEC TR 60825-9 in determination of hazards of non coherent optical radiation sources. Specific areas reviewed in detail include those relating to hazards of ultraviolet radiation, retinal thermal hazard and blue light photochemical hazard. The effect of spectral temperature on relative risk relating to retinal thermal hazard and blue light photochemical hazard are outlined. Assessment of risk factors of these hazards was determined using a range of measurement devices including spectral radiometer, broad band power meter and a locally developed device for determination of pulse profile of pulsed light sources.     

Erythrocyte distribution profiles during sedimentation as determined by helium-neon laser light

A method for the measurement of erythrocyte distribution during sedimentation is presented. The results obtained, using the variation of helium-neon laser-light intensity, are presented to show the erythrocyte distribution at various haematocrits with respect to height (or depth) and width of the sample holder, and time duration for sedimentation.     

Localization of coherent sources by simultaneous MEG and EEG beamformer

Simultaneous magnetoencephalography (MEG) and electroencephalography (EEG) analysis is known generally to yield better localization performance than a single modality only. For simultaneous analysis, MEG and EEG data should be combined to maximize synergistic effects. Recently, beamformer for simultaneous MEG/EEG analysis was proposed to localize both radial and tangential components well, while single modality analyses could not detect them, or had relatively higher location bias. In practice, most interesting brain sources are likely to be activated coherently; however, conventional beamformer may not work properly for such coherent sources. To overcome this difficulty, a linearly constrained minimum variance (LCMV) beamformer may be used with a source suppression strategy. In this work, simultaneous MEG/EEG LCMV beamformer using source suppression was formulated firstly to investigate its capability over various suppression strategies. The localization performance of our proposed approach was examined mainly for coherent sources and compared thoroughly with the conventional simultaneous and single modality approaches, over various suppression strategies. For this purpose, we used numerous simulated data, as well as empirical auditory stimulation data. In addition, some strategic issues of simultaneous MEG/EEG analysis were discussed. Overall, we found that our simultaneous MEG/EEG LCMV beamformer using a source suppression strategy is greatly beneficial in localizing coherent sources.     

Electron microscopy of cardiac myosin: Its shape and properties as determined by the regulatory light chain

Summary Structural properties of dog cardiac myosin and the influence of the regulatory light chain (LC2) on the shape of myosin heads were investigated by electron microscopy. LC2 was reversibly removed using a neutral protease from myopathic hamsters (Margossian,J. Biol. Chem. 260 (1985) 13747–54). The distribution of myosin head length centred around 17 nm with the mean length being 18.9 nm. Statistical analysis suggested that myosin heads became more globular upon removal of LC2. No extensive aggregation of myosin could be detected after LC2 was dissociated, either by sedimentation velocity or by gels run under non-denaturing conditions. The centre-to-centre distance between heads remained constant at about 21 nm, regardless of the presence or absence of LC2. The distribution of length of the globular region reveals two peaks at 7.5 and 9.5 nm, suggesting an extended and a shorter configuration of this region. The decrease in mass at the head/tail junction upon LC2 removal suggests that it is the binding site for the regulatory light chains. A bend at 57 nm from the head/tail joint was sometimes noticed, corresponding to the myosin hinge region. In high resolution micrographs individual particles revealed invaginations along the contours of the head, possibly delineating the boundaries of structural domains within the head. The conformation of arrowheads in actin decorated with either subfragment 1 (S1) or heavy meromyosin (HMM) was investigated in the presence and absence of LC2.     

Finger arterial compliance as determined by transmission of light during mental stress and reactive hyperaemia

A near-infrared finger photoplethysmogram adopting a wavelength of 810 nm provides data pertaining to the pulsatile a.c. component of finger blood flow (ΔI) superimposed on the transmitted d.c. components in a normal (I: tissue plus blood) and an ischaemic circulatory state (I _t: tissue only). Simultaneous recording of finger blood pressure provides data pertaining to the distending pulse (PP) and mean blood pressure. Based on the Lambert-Beer law, indices of the arterial compliance (CI=ΔI/I/PP) and distensibility [DI=ΔI/I/ln(I _t/I)/PP] are advocated for assessing finger vasculature. The functional relationships between transmural pressure and CI and DI were examined using finger occlusion while performing an arithmetic test (i.e. a mental stress) in 16 females, and during reactive hyperaemia in 5. Gradual occlusion of the finger was conducted at 20-s intervals and the beat-by-beat transmural pressure was determined by calculating mean blood pressure minus the occluding cuff pressure. Logarithmically transformed CI and DI data were linearly associated with the transmural pressure; thus, the estimates obtained at a transmural pressure of 40 mmHg were chosen as an arbitrary reference point (CI40 and DI40). The results indicated that CI40 and DI40 were reduced while performing an arithmetic test, and increased during reactive hyperaemia. Responses were larger for CI40 than for DI40. In conclusion, noninvasive finger occlusion allowed the measurement of the compliance/distending pressure relationship, and CI40 could be utilised to evaluate changes in finger vascular tone. Electronic Publication     

Neurochemical anatomy of the zebrafish retina as determined by immunocytochemistry

The zebrafish retina is rapidly becoming a major preparation for the study of molecular genetic mechanisms underlying neural development and visual behavior. Studies utilizing retinal mutants would benefit by the availability of a data base on the distribution of neurotransmitter systems in the wild-type fish. To this end, the neurochemical anatomy of the zebrafish retina was surveyed by light microscopic immunocytochemistry. An extensive series of 60 separate antibodies were used to describe the distribution of major transmitter systems and a variety of neuron-associated membrane channels and proteins. These include markers (i.e., antibodies against enzymes, receptors, transporters) for transmitters: GABA, glycine, glutamate, biogenic amines, acetylcholine, cannabinoids and neuropeptides; as well as a sample of voltage-gated channels and synapse associated membrane proteins. Discussion of the comparative localization of these antibodies is restricted to other teleost fishes, particularly goldfish. Overall, there was great similarity in the distribution of the various markers, as might be expected. However, there were some notable differences, including several antibodies that did not label zebrafish at all, even though goldfish retinas that were processed in parallel, labeled beautifully. This survey is extensive, but not exhaustive, and hopefully will serve as a valuable resource for future studies of the zebrafish retina.     

Class-specific immune response to Yersinia enterocolitica serotype O9 antigens as determined by enzyme-linked immunosorbent assay.

An enzyme-linked immunosorbent assay (ELISA) using lipopolysaccharide (S-LPS) as the antigen was used to analyze the antibody response in rabbits orogastrically and intravenously infected with virulent (plasmid-bearing) Yersinia enterocolitica O9 strains (pYV+) and with the avirulent (plasmid-cured) derivatives (pYV-). A significative response of immunoglobulin G (IgG), IgA, and IgM antibodies against the S-LPS antigen was evident in sera from the rabbits orogastrically infected with pYV+ strains. This immune response was stronger and persisted longer than those obtained with the corresponding pYV- strains. In contrast, few differences were observed in the titers and evolution of IgG, IgA, and IgM antibodies against the S-LPS antigen in rabbits intravenously infected with pYV+ and pYV- strains. These results suggest that the necessity of the virulence plasmid for the establishment of infection by Y. enterocolitica serotype O9 is conditioned by the infection route used. When the S-LPS ELISA was compared with the radial immunodiffusion test using the native hapten as the antigen, the results showed that the ELISA technique was more sensitive. However, only those sera obtained between 2 and 8 weeks postinfection from rabbits intravenously infected with plasmid-bearing strains were positive in the radial immunodiffusion test.     

Comparison of molecular weight distributions of polymers determined by dynamic light scattering

Several methods for the treatment of experimental data (including 3 different parameter-fitting procedures, histograms, and Provencher's constrained regularization) are considered which allow to obtain molecular weight distributions w(M) from quasielastic light scattering measurements. As a result of the introduction of a few improvements to these methods described in the literature, we were able to use more severe criteria for the quality of the distribution functions obtained, based on the mean-square deviation rather than on the coincidence of a few first moments. The quality of five investigated inversion methods was compared on the basis of simulated and experimental data for flexible chain polymers (polystyrene standards) in dilute solution.     

Antimicrobial susceptibilities of mycobacteria as determined by differential light scattering and correlation with results from multiple reference laboratories.

The DAWN Model B laser light scattering instrument (Wyatt Technology Corporation, Santa Barbara, Calif.) was evaluated to assess its potential to provide rapid mycobacterial antimicrobial susceptibility test results. For Mycobacterium tuberculosis there was a clear separation between susceptible and resistant results with the isolates tested, and there was excellent correlation with reference laboratory results. For Mycobacterium avium there was no obvious breakpoint between susceptible and resistant results with the isolates tested, and correlation with reference laboratory results was less good than for M. tuberculosis. However, for M. avium there was also less agreement among reference laboratory results than for M. tuberculosis. Significant instrument design and software program changes would be required for the instrument to become a useful tool for mycobacterial susceptibility testing in the diagnostic laboratory.     

Calibration frequency as determined by analysis of machine stability

Simple statistical analysis is applied to the evaluation of the output measurements of equipment used in radiotherapy. The calibration frequency is calculated based on the stability of the equipment and the performance parameters required by the quality control criteria.     

The effect of light exercise upon blood flow velocity determined by laser-Doppler flowmetry

PRIMARY OBJECTIVE: The dominant, 0.1 Hz frequency, Traube-Hering component of blood flow velocity, which is related to baroreflex activity, may be modulated through the established techniques of manipulative medicine. Light exercise programmes, appropriate for use by the elderly and collectively termed gymnastique douce, also are believed to impact the baroreflex in a positive manner. Our objective was to test the relationship between the Traube-Hering oscillation and light exercise. METHODS: Using laser-Doppler flowmetry to quantify the Traube-Hering and other components of the blood flow velocity oscillation, we compared flowmetry records of 10 subjects before and immediately following a light-exercise programme. RESULTS: The data show that the light exercise programme amplifies the 0.1 Hz component of the blood flowmetry record. CONCLUSIONS: The 0.1 Hz component of blood-flow velocity is physiologically linked to baroreflex activity. It is this component that is augmented by a light exercise programme.     

The synergistic effects of the IL-9 gene and environmental exposures on asthmatic Taiwanese families as determined by the transmission/disequilibrium test

Asthma occurs in genetically susceptible individuals in the presence of environmental factors. The interleukin-9 (IL-9) gene, one of the cytokine genes located on chromosome 5q31, plays an important role in the development of asthmatic syndrome by enhancing both T-cell and mast-cell function. This study investigated GT repeat polymorphism of the IL-9 gene and the gene-environment interactions, which may predispose individuals to asthma and atopy pathogenesis. In this study, we used the transmission/disequilibrium test (TDT) to investigate the relationship between asthma and the IL-9 gene by studying 123 parent-offspring trios and 91 siblings. For allele-specific TDT chi-squared test, allele 122 of the IL-9 gene showed significant association with asthmatics with specific IgE against house dust (HD) (P = 0.038). The additions of covariates to TDT to conduct the synergistic effects between the IL-9 gene and environmental factors into account were estimated by conditional logistic regression models. The odds ratio for transmission of allele 122 of the IL-9 gene was 1.23 (P = 0.28) for all asthmatic probands. There was slight increased interaction effect on asthma between transmission of allele 122 of IL-9 gene to offspring and who were exposed to the fur of pets (OR = 3.33, P = 0.047). We also detected elevated odds of transmission of allele 122 to atopic asthmatic probands (OR = 2.08, P = 0.03) and offspring with very high levels of serum IgE (> or = 800 IU mL(-1)). In conclusion, this study has found that the IL-9 gene was slightly associated with asthmatics who have positive specific IgE against Der p (or Der f) and house dust, when information on environmental factors was incorporated as effect modifiers.     

Co-secretion of two distinct kappa light chains by the mu-9 hybridoma

Mu-9 is a monoclonal antibody (MAb) specific for the CSAp antigen (Ag) expressed by colorectal cancers. By using variable (V)-region-specific primers, the respective VH and VL sequences of Mu-9 were polymerase chain reaction (PCR)-amplified. However, chimeric Ab (cMu-9-1) constructed from these PCR-amplified V sequences failed to bind the CSAp Ag. Although the light chain of murine Mu-9 was not glycosylated, that of cMu-9-1 was found to be O-glycosylated, as confirmed by reducing SDS-PAGE analyses, glycoprotein blotting and O-linked specific deglycosylation studies. Removal of O-linked oligosaccharides either by enzymatic digestion or by blocking O-glycosylation with a specific inhibitor did not restore the immunoreactivity of cMu-9-1, indicating that light chain O-glycosylation was not the cause for lack of immunoreactivity. We reported earlier that screening of a Mu-9 cDNA library uncovered the presence of an additional light chain sequence that was later proven to be the authentic light chain of Mu-9. Analyses of the cDNA sequence encoding the nonimmunoreactive light chain, however, revealed no defects that would preclude the sequence from being translated and secreted by the murine hybridoma. By adapting the Mu-9 hybridoma culture to serum-free conditions, we confirmed the secretion of low levels of O-glycosylated light chain. The biological significance of the O-glycosylation as well as the cosecretion of both light chains with respect to allelic exclusion are discussed.     

Tissue distribution of the Pk antigen as determined by a monoclonal antibody

Using an anti-Pk monoclonal antibody (mAb) designated CPK-1, the expression of the Pk antigen was assessed on normal human tissue from non-Pk individuals. Although the Pk antigen was detected on fibroblasts and blood vessels as previously reported, it was also found on smooth muscle cells of the digestive tract and the urogenital system. Pk was also found on glandular cells of the stomach, oesophagus and prostate. Additionally, CPK-1 reacted weakly with oesophagus squamous cells, and a small number of glomeruli and tubules in the kidney. The mechanism of expression of the Pk determinant in non-Pk individuals is discussed.     

Refined HLA-B3501 anchor and non anchor residue motif for of 9-MER - 11-MER peptides

HLA-B^*3501 is associated with subacute thyroditis and fast progression of AIDS. An important prerequisite to investigate the T cell recognition of HLA-B^*3501-restricted antigens is the characterization peptide-HLA-B^*3501 interactions. Therefore the HLA-B^*3501 interactions of 240 chemically synthesized 9-mer - 11-mer peptides were determined in quantitative peptide binding assays. The results were statistically analyzed to evaluate the influence of both anchor and nonanchor positions and the predictability of peptide binding. The importance of Pro as auxiliary anchor was extended to 10-mers and 11-mers as opposed to Ala, which associated with poor binding. Aliphatic hydrophobic nonanchor residues at positions 3, 5, and 7 (8) of 9-mers (10-mers) and position 3 of 11-mers significantly enhanced HLA-B^*3501 binding. Similar effects were observed for aromatic residues at position 1 of 9-mers - 11-mers, acidic at position 8 and 10 of 11-mers. Negative effects were observed for Pro at position 1 and for 9-mers (11-mers) carrying residues with positively charged side chains at position 3, 5 and 7 (8). These findings were validated by the successful prediction of fifty-five 9-mers - 11 mers.     

Distribution of ehrlichiae in tissues as determined by in-situ hybridization

Specific identification of ehrlichiae in the tissues and determination of their distribution is difficult. In this study, an in-situ hybridization method was developed to detect ehrlichial 16S rRNA in tissue specimens from mice experimentally infected with the HF strain. This strain is closely related to Ehrlichia chaffeensis, the agent of human monocytic ehrlichiosis. HF strain-specific 16S rRNA was detected in endothelial cells and monocyte-macrophages in the liver, lungs, bone marrow, spleen, lymph nodes, and large and small intestinal tissues. The results suggest that the in-situ hybridization method with a digoxigenin-labelled RNA probe specific to ehrlichial 16S rRNA will be useful for post-mortem diagnosis and for the histopathological investigation of ehrlichial infection.