Sources of unwanted variability in measurement and description of skin surface topography

Background/aims: Quantitative measurement of skin roughness has proved to be a valuable tool in the efficacy-control of external applications, but it suffers from not yielding easily comparable results. The most important sources of inter-observer variability are high-pass filters used to separate roughness and waviness, and low-pass filters which result from the finite resolution of the instrument or from the finite sampling interval of digital measurement. In the present study, the effects of high-pass filters and sampling intervals on the roughness measured were investigated. Methods: Dynamically focusing optical profilometry was used to measure the surfaces of negative replicas of healthy human skin. High-pass cut-off wavelengths and sampling intervals were varied systematically. Results/conclusions: Virtually unbiased estimates for the roughness parameters K, Sk, R_q, and R_a can be obtained using sampling intervals of 40 or even 80 μm. Regarding these roughness parameters, it is far better to do more scans than to shorten the sampling interval. The roughness parameters R_z, R_p, R_t, R_pm, R_max, P_t, on the other hand are very sensitive to the influence of the sampling interval; to achieve satisfying estimates, the sampling interval should be no longer than 2 to 5 urn; as an important parameter’of the measurement, it is worthy of remark and should always be indicated. The way the mean square roughness R_q depends on the cut-off wavelength is not well described by the Sayles-Thomas-relation R_q～λ_c^0.5. If the power-spectrum |h*(v)|² approximates sufficiently to a power law, |h*(v)|²～v^δ, a better estimate is given by R_q～λ_c^γ with γ=-(δ+1)/2. In many cases, γ=1 or R_q～λ_c will suffice.     

Enhanced metabolic activation of chemical hepatocarcinogens in woodchucks infected with hepatitis B virus

The metabolism of chemical carcinogens was investigated in liverpreparations from 28 captive woodchucks (Marmotamonax). Of these,23 were naturally infected with the wood-chuck hepatitis virus(WHV), and eight also had primary hepatocellular carcinoma (PHC).Twenty-nine parameters were investigated in liver subcelhilarfractions, including cross-reactivity with HBsAg, and biochemicalparameters, such as -glutamyl transpeptidase, cytochrome P-450and mirosomal monooxygenases (aryl hydrocarbon hydroxylase,ethodycoumarin and ethoxyresorufin deethylases, amino-pyrineand dimethylnitrosamine demethylases, and testosterone 7-and16ß- and 6ß-hydroxylases), uridine 5'-diphos-phoglucuronosyltransferase, GSH and related enzymes (peroxidase, reductaseand S-transferase), as well as other cytosolic enzyme activities(glucose 6-phosphate and 6-phosphogluconate dehydrogenases,NADPH- and NADH-dependent diaphorases, and DT diaphorase). Inaddition, liver preparations were used in order to quantifythe metabolic activation into bacterial mutagens of five procarcinogens(aflatoxin B¹, the pyrolysis products Trp-P-2 and MelQ, 2-aminofluoreneand dimethylnitrosamine) and the decrease of potency of threedirect-acting mutagens (sodium di-chromate, ICR 191 and 4-nitroquinoline1-oxide). WHV infection produced a significant stimulation ofcarcinogen metabolism, as shown by the simultaneous change indetoxification parameters (GSH depletion) and activation indices(enhancement of microsomal monooxygenases and of pro-carcinogenactivation into mutagenic metabolites). There were no significantdifferences between WHV-positive samples from animals, withoutPHC and the noncancerous tissue of PHC-bearing animals, whereasa decrease of both activation and detoxification indices wasrecorded in the turmorous tissue. There was a considerable interindividualvariability among WHV carriers, which was tentatively ascribedto genetic factors. Pregnancy was the only known factor influencingthe results in WHV carriers. However, even by excluding pregnantanimals, the effects on carcinogen metabolism produced by WHVinfection were still statistically significant. These results,together with previous data obtained in humans, revealed thatmetabolic factors may play a role in the synergism between viralhepatitis and chemical hepato-carcinogens in the etiopathogenesisof PHC.     

Localization of SNARE proteins and secretory organelle proteins in astrocytes in vitro and in situ

Astrocytes are capable of regulated release of messenger molecules. Astrocytes cultured from new born rodent brain express a variety of classical presynaptic proteins. We investigated the question whether the capability to express synaptic proteins in culture was a feature only of immature astrocytes, and whether these proteins were also expressed by astrocytes in situ. Experiments were performed with transgenic mice expressing the enhanced green fluorescent protein under the control of the human glial fibrillary acidic protein promoter. Using double fluorescence and astrocytes cultured from 1 to 16 day-old animals we show that the astrocytic expression of synaptic proteins in culture is invariant of the age of donor animals. Culturing can induce the astrocytic expression of specific synaptic proteins such as SV2, synaptophysin and SNAP-25. Astrocytes in brain sections of 1-16 day-old animals revealed a punctuate immunofluorescence for secretory carrier membrane protein (SCAMP), SNAP-23, synaptobrevin II, and cellubrevin, to a minor extent for SNAP-25 and synaptophysin, and none for SV2. Our results demonstrate that cultured astrocytes express synaptic proteins not present in situ. Nevertheless, astrocytic organelles in situ are equipped with molecules that could be involved in regulated exocytosis of messenger substances.     

Spectral analysis of spontaneous contractions of the isolated portal vein of rats

Summary The spontaneous contractions of segments of rat portal veins have been examined in vitro under isotonic and isometric conditions. The power density spectra of recorded time series lasting 10–60 min were calculated. The spectra usually consist of harmonic frequency components. Only during shorter periods of analysis (10 min time series) we sometimes found additional non-harmonic components. All frequency components are proportionally shifted by changes of the bath temperature according to an average Q₁₀ of 2.0. Increase of the load decreases the frequency of the contractions.The results of the spectral analysis, indicating a preponderance of a single source of periodicity, were supported by direct evidence of a pacemaker region. By recording contractions after systematic dissections of the portal vein segment, we found that spontaneous activity is generated at the central end of the segment.This work was supported by the Austrian Research Fund     

A staphylococcal radioimmunoassay for detection of antibodies toMycoplasma pneumoniae

A radioimmunoassay (RIA) which depends on the property of protein A ofStaphylococcus aureus to combine with the Fc-fragment of immunoglobulins was developed.This technique was employed to measure antibodies in human and various animal sera. It could be demonstrated that the staphylococcal RIA was at least as sensitive as the previously described radioimmunoprecipitation technique in detecting antibodies toM.pneumoniae in human sera. In addition, antibodies toM.pneumoniae could be demonstrated in sera of hamsters intranasally inoculated with the organisms. Antibodies could also be demonstrated in rabbit sera after immunization withM.pneumoniae. The test proved to be considerably more sensitive than conventional tests for detection of antibodies to the organisms. The test requires only small amounts of reagents and is relatively inexpensive.The results were presented in a preliminary form at the annual meeting of the Local Branch of the American Society for Microbiology, Frankfurt, March 1976 and the 77th ordinary meeting of the Society for General Microbiology, Glasgow, September 1976     

Suggestions for the assessment of the allergenic potential of genetically modified organisms

The prevalence of allergic diseases has been increasing continuously and, accordingly, there is a great desire to evaluate the allergenic potential of components in our daily environment (e.g., food). Although there is almost no scientific evidence that genetically modified organisms (GMOs) exhibit increased allergenicity compared with the corresponding wild type significant concerns have been raised regarding this matter. In principle, it is possible that the allergenic potential of GMOs may be increased due to the introduction of potential foreign allergens, to potentially upregulated expression of allergenic components caused by the modification of the wild type organism or to different means of exposure. According to the current practice, the proteins to be introduced into a GMO are evaluated for their physiochemical properties, sequence homology with known allergens and occasionally regarding their allergenic activity. We discuss why these current rules and procedures cannot predict or exclude the allergenicity of a given GMO with certainty. As an alternative we suggest to improve the current evaluation by an experimental comparison of the wild-type organism with the whole GMO regarding their potential to elicit reactions in allergic individuals and to induce de novo sensitizations. We also recommend that the suggested assessment procedures be equally applied to GMOs as well as to natural cultivars in order to establish effective measures for allergy prevention.     

No evidence for involvement of the calpain-10 gene 'high-risk' haplotype combination for non-insulin-dependent diabetes mellitus in early onset obesity

In light of evidence of linkage of obesity to chromosome 2q31-q37, we hypothesized that the calpain-10 gene 'high-risk' haplotype combination for non-insulin-dependent diabetes mellitus (NIDDM) is involved in early onset obesity. We screened the NIDDM 'high-risk'-haplotype combination formed by the alleles 112 and 121 of the polymorphisms UCSNP-43, -19, and -63 in 166 families consisting of an extremely obese child or adolescent (mean BMI percentile: 99.3+/-1.38), one or more obese sibs (mean BMI percentile: 97.42+/-2.88), and both of their parents. Genotyping for three calpain-10 gene polymorphisms was performed by polymerase chain reaction (PCR) with (a) length polymorphism detection (UCSNP-19) or (b) allele-specific PCR (UCSNP-43 and -63). To allow for correct haplotype assignment all individuals were additionally genotyped for two microsatellite markers (D2S125 and D2S2338). We followed a hierarchical test procedure. As the first step, model-free linkage analysis was performed using maximum likelihood binomial statistics. The second stage consisted of a one-sided asymptotic pedigree disequilibrium test for the UCSNP-43 and on an exploratory level for the other SNP-markers and all haplotypes formed by the three SNPs. The final stage investigated the reported haplotype combination. We failed to detect an initial linkage of obesity to this region (LOD score <0.4). All subsequent exploratory analyses were negative. Our analysis of the relationship between the NIDDM 'high-risk' haplotype combination and extreme early onset obesity revealed no evidence for linkage and association.     

The position of pulmonary carcinoids within the spectrum of neuroendocrine tumors of the lung and other tissues

Bronchopulmonary carcinoids comprise 25% of all human carcinoids. The World Health Organization divides them into typical (TC) and atypical forms (ATC), distinguished by differences in mitotic counts lower or higher than 2/2 mm(2) and the presence or absence of necrosis. The reproducibility of this classification with respect to the borderline cases with 1-2 mitotic counts/2 mm(2) has been questioned. We have analyzed 15 TCs and 20 ATCs by comparative genomic hybridization. Loss of 11q was the most frequent aberration in ATC (55%), but was observed only twice in TC (13%). Deletions of 3p were seen only in ATC (25%). Meta-analysis of our data and data from 218 neuroendocrine tumors and 50 non-small-cell lung carcinomas obtained from the literature revealed differences between carcinoids and carcinomas. For example, loss of 5q is frequent in lung carcinomas (75%) but is rarely seen in carcinoids (1.4%). Deletions of 11q are less frequent in neuroendocrine lung carcinomas than in ATC. To obtain a more objective survey of the relationship of pulmonary carcinoids to other neuroendocrine tumors and lung carcinomas, we created a hierarchical clustering dendrogram. This statistical approach resulted in a clear separation of carcinoids and carcinomas, which both built up different clusters. In summary, this study demonstrates the benefit of chromosomal analysis supplementary to the diagnosis of bronchopulmonary carcinoids. We also identified the feasibility of hierarchical clustering to get some clues on relationship between different tumor types. This study further argues against a transition of ATC to high-grade neuroendocrine lung carcinoma.