Analysis of short wavelength infrared radiation during laser welding of plastics.

In this paper, a new measurement system and a new approach in calculation for infrared (IR) radiation investigation in quasi-simultaneous transmission laser welding of plastics are presented. The measurement system is based on a MW/SWIR (medium-wave/short-wave IR) camera and optical filters narrowing the spectral region to SWIR. The measured signals contain radiation from the melted zone in between the semitransparent and absorbing polymers, as well as radiation from the surface and interior of the semitransparent polymer. The new calculation approach was developed to distinguish between these signals. It is based on simplification of the process to two places with two temperatures (surface and molten interface) and knowledge of the spectral optical properties of the material, filters, and camera response. The results of measurement and calculation for three different optical filters and polyoxymethylene samples with two thicknesses are shown and discussed. Good agreement is obtained for the calculation variant using normal transmissivity of the semitransparent polymer.

Risk factors in alcohol associated breast cancer: alcohol dehydrogenase polymorphism and estrogens.

Chronic alcohol consumption is associated with an increased risk for breast cancer, even if consumed in moderate doses. Since acetaldehyde is a carcinogenic factor associated with chronic alcohol consumption, individuals with the alcohol dehydrogenase 1C*1 allele (ADH1C*1 allele) seem to be at particular risk, since this allele encodes for a rapidly ethanol metabolizing enzyme leading to increased acetaldehyde levels. Since recent epidemiological studies demonstrated an increased risk for breast cancer for individuals with the ADH1C*1 allele, we have investigated here ADH1C genotypes in moderate alcohol consumers. Furthermore, estradiols are also known risk factors for breast cancer and acute alcohol ingestion in high doses results in increased serum estradiol concentrations. Thus, in the present study, we tested the effect of low ethanol doses on estrogen serum concentrations. We analyzed the ADH1C genotype in 117 moderate alcohol consumers with breast cancer and in 111 age-matched women with alcohol associated diseases without cancer (74 cirrhotics, 22 patients with pancreatitis and 15 alcohol dependent patients). In addition, 107 healthy controls were studied. Genotyping of the ADH1C-locus was performed using polymerase chain reaction-based restriction fragment length polymorphism methods on leukocyte DNA. To study the effects of ethanol on estradiol levels, ethanol in a dose of 0.225 g/kg body weight was given orally to 8 premenopausal women at various time points of their menstrual cycle. Thereafter estradiol serum concentrations were measured over time. The allele frequency of the ADH1C*1 allele was found to be significantly increased in moderate alcohol consumers with breast cancer as compared to age-matched alcoholic controls without cancer (62% vs. 41.9%, p=0.0035). Women with the ADH1C*1,1 genotype were found to be 1.8 times more at risk for breast cancer than those with another genotype (95% CI 1.431-2.330, p<0.001). Oral ethanol increased serum estradiol levels significantly by 27-38%. The data demonstrate that moderate alcohol consumers with the ADH1C*1 allele have an increased risk to develop breast cancer and even small amounts of alcohol increase serum estradiol levels significantly in premenopausal women especially in the midphase of the menstrual cycle.

Increased cancer risk in heavy drinkers with the alcohol dehydrogenase 1C*1 allele, possibly due to salivary acetaldehyde.

BACKGROUND: Chronic ethanol consumption is associated with an increased risk of upper aerodigestive tract cancer. As acetaldehyde seems to be a carcinogenic factor associated with chronic alcohol consumption, alcoholics with the alcohol dehydrogenase (ADH) 1C*1 allele seem to be particularly at risk as this allele encodes for a rapidly ethanol metabolising enzyme leading to increased acetaldehyde levels. Recent epidemiological studies resulted in contradictory results and therefore we have investigated ADH1C genotypes in heavy alcohol consumers only. METHODS: We analysed the ADH1C genotype in 107 heavy drinkers with upper aerodigestive tract cancer and in 103 age matched alcoholic controls without cancer who consumed similar amounts of alcohol. Genotyping of the ADH1C locus was performed using polymerase chain reaction based on restriction fragment length polymorphism methods on leucocyte DNA. In addition, ethanol was administered orally (0.3 g/kg body weight) to 21 healthy volunteers with the ADH1C*1,1, ADH1C*1,2, and ADH1C*2,2 genotypes, and 12 volunteers with various ADH genotypes consumed ethanol ad libitum (mean 211 (29) g). Subsequently, salivary acetaldehyde concentrations were measured by gas chromatography or high performance liquid chromatography. RESULTS: The allele frequency of the ADH1C*1 allele was found to be significantly increased in heavy drinkers with upper aerodigestive tract cancer compared with age matched alcoholic controls without cancer (61.7% v 49.0%; p = 0.011). The unadjusted and adjusted odds ratios for all cancer cases versus all alcoholic controls were 1.67 and 1.69, respectively. Healthy volunteers homozygous for the ADH1C*1 allele had higher salivary acetaldehyde concentrations following alcohol ingestion than volunteers heterozygous for ADH1C (p = 0.056) or homozygous for ADH1C*2 (p = 0.011). CONCLUSIONS: These data demonstrate that heavy drinkers homozygous for the ADH1C*1 allele have a predisposition to develop upper aerodigestive tract cancer, possibly due to elevated salivary acetaldehyde levels following alcohol consumption.

[Caspases--a target for intervention in diseases which are still difficult to treat]. / Kaspasy--cíl zásahu dosud obtízne lécitelných nemocí?

The central role in apoptosis, which is a precondition of the normal development of the organism, as played by caspases, a family of highly specific cysteine proteases. Caspases released from procaspases in a certain surplus induce apoptosis, with simultaneous cleavage of some cellular proteins essential for cellular growth. Caspase activity (initiative or effector one) is the resultant and final physiological as well as pathological stimulus, in which impairment of the cell membranes, function of mitochondria and other organelles, and also DNA takes place. The interest is focused on caspases inhibitors, which could influence, at some stages, some diseases which are difficult to control or which are still untreatable (tumours, neurodegenerative diseases, viral liver diseases, inflammatory diseases). The caspases family includes 14 enzymes, the best examined ones being caspase-1 and caspase-3. The therapeutically usable protease inhibitors include, for the time being, serine proteases and some metaloproteases, whereas the inhibitors of cysteine proteases have not been introduced into practice yet. Synthesis of caspases inhibitors, in particularly those of non-peptidic character, the so-called small molecules, is one of the strategic aims of contemporary research of the treatment of the above-mentioned diseases.

Renewal of the culture medium induces a temporary decrease in the gap junctional communication accompanied by degradation and re-establishment of gap junctions in the V79-4 Chinese hamster cell line.

To replace the culture medium with a fresh one is a routine action of the mammalian cell culture technique. It is generally assumed that this act per se does not cause any significant physiological response of a cell population that would significantly interfere with the experimental procedures in culture. However, in this series of experiments we demonstrate that the exchange of the culture medium for a fresh one may induce a significant temporary decrease in the GJIC, assessed by the dye coupling method in the V79-4 Chinese hamster cell line. This effect is accompanied by a degradation of gap junctions and their re-establishment assessed by the semi-quantitative immunocytochemistry of connexin43. The minimum value of GJIC was reached 45 min after the exchange of the medium. Afterwards, GJIC grew up again, reaching the standard value 3 or 4 h later. This effect does not just result from the exchange of medium as a mechanical action, is not caused by the change of pH and is of quantitative character. The fresh medium loses its capability to reduce GJIC after 3 h of conditioning with the same cells. We found that the value of the early inhibition of GJIC observed during the first 2 h of treatment with the inhibitor of GJIC-EG (applied together with a fresh culture medium)--was indistinguishable from the effect of the exchange of medium itself. Only after that point of time is the EG-induced inhibition of GJIC definitely distinguishable. The results demonstrate that a simple exchange of the culture medium, which is generally implemented in various experiments in culture, may cause serious physiological, biochemical and even morphological responses of cells and thus affect the final results of experiments in culture, especially regarding the early effects of drugs. Consequently, to avoid an undesirable response of the cell population reported in this paper we recommend to apply or remove drugs using a medium conditioned with the same cells for at least 3 h.

Thickness measurement of thin dielectric films by evanescent total reflection fluorescence.

The electric field of an evanescent wave generates fluorescence in the interface between a dielectric surface and an adjacent, fluorescing, medium of lower refractive index. The difference between the fluorescing signals from covered and noncovered surfaces enables nondestructive measurement of the film thickness to be made in the range 1-15 nm.

Spinach chloroplast ATP-dependent endopeptidase: Ti-like protease.

The soluble fraction of spinach chloroplast was used for purification and characterization of an ATP-dependent protease. Purification included Q Sepharose Fast Flow, hydroxylapatite and FPLC Superose 6 column chromatography. The isolated enzyme requires ATP and Mg2+ for stimulation and represents a ubiquitin independent serine protease, containing essential sulphydryl group(s). By using fluorogenic peptides a similarity of chloroplast protease to Escherichia coli Ti protease was observed. The chloroplast protease is immunochemically cross-reactive with the bacterial protease Ti.

[The effect of kampo preparations and their effect on peptidase activity in damage caused by free radicals]. / Ochranný úcinek Kampo pri poskození organismu volnými kyslíkovými radikály a jejich úcinek na aktivitu peptidáz.

The activity of peptidases (trypsin from bovine pancreas and trypsin-like enzymes from the liver rat homogenate) was influenced by five preparation of Kampo medicine, TJ-9 (Sho-Saiko-To), TJ-15 (Oren-Gedoku-To), TJ-23 (Toki-Shakuyaku-San), TJ-96 (Saiboku-To), and TJ-114 (Sairei-To) and studied in relation to their effect on the uptake of free oxygen radicals demonstrated earlier. On the basis of increased activity of trypsin and trypsin-like enzymes and the previously found capability of uptaking free oxygen radicals, the mechanism of action of the Kampo preparations may be assumed to be connected not only with a direct support of enzymes of digestion and increased activity of peptidases, capable of eliminating oxidatively damaged proteins, but with an antioxidative effect as well, which prevents increased cumulation of oxidatively damaged macromolecules and the action of superoxide radicals developed earlier by the well-known and trypsin-stimulated conversion of xanthinedehydrogenase to xanthinoxidase.

Biotransformation and in vitro activity of an arabinosylcytosine 5'-chloro-5'-deoxy analog.

5'-Chloro-5'-deoxyarabinosylcytosine (5'-chloro-araC), a lipophilic and cytidine-deaminase resistant analog of the cytotoxic agent arabinosylcytosine (araC) was evaluated in terms of bioactivation, transformation and its cytotoxic activity in vitro. 5'-Chloro-araC interferes with DNA synthesis (IC50 = 2.8 mumol/l) and inhibits the growth of L1210 cells in suspension culture (IC50 = 1.05 mumol/l) and in the soft agar assay (IC50 = 0.65 mumol/l). Being phosphorylated to the triphosphate of araC-araCTP (5'-triphosphate of araC), 5'-chloro-araC has the same mechanism of action as arabinosylcytosine. In alkaline solutions 5'-chloro-araC is transformed to another (cytostatically inactive) araC analog--2',5'-anhydroarabinosylcytosine--but at physiological pH and temperature conditions, it has sufficient stability to be phosphorylated and thus activated. A lower rate of araCTP formation from 5'-chloro-araC explains the somewhat lower cytotoxic effect of this compound against various established cell lines in vitro compared to araC. Lipophilicity that would allow an oral drug formulation and certain other superior physico-chemical and biochemical characteristics of 5'-chloro-araC make this compound an interesting candidate for further investigations.

Electrochemical properties of polycyclic compounds studied by the polarographic method in anhydrous systems. VIII. The influence of proton-donor on reduction of carcinogenic nitrogen compounds in dimethylformamide.

The authors have studied the electrochemical behavior of a series of carcinogenic and inactive heterocyclic compounds in anhydrous medium in the presence of a proton-donor. As anhydrous medium the authors used anhydrous dimethylformamide as proton-donor phenol. In the presence of proton-donor there had occurred on polarographic reduction of the employed carcinogenic heterocyclic compounds changes in the number of polarographic waves. Between the two original waves in these compounds there arose in the presence of phenol a new wave. In non-carcinogenic heterocyclic compounds such an effect of phenol was not noted. In the present paper the authors discuss the possible mechanism of electroreduction of carcinogenic and inactive heterocyclic compounds in anhydrous medium in the presence of a proton-donor.

Electrochemical properties of polycyclic compounds studied by the polarographic method in anhydrous systems. VII. Polarographic oxidation of carcinogenic hydrocarbons in dimethylformamide.

The electrooxidation of polycyclic carcinogenic hydrocarbons in dimethylformamide solutions was studied by polarography. The results generally have confirmed that a correlation exists between oxidation potentials and carcinogenic activity of the studied polycyclic aromatic hydrocarbons. The half-wave potentials of the polarographic curves have been found to be directly related to the root xn of the Hückel secular equation for the highest bonding orbital and to the reduction potentials measured in dimethylformamide.

Carcinogenicity and polarographic behaviour of dibenzo[a,h]pyrene, 4,11-diazadibenzo[a,h]pyrene and 7,14-diazadibenzo[a,h]pyrene.

In a simultaneous test of carcinogenicity the writers have studied the activities of dibenzo[a,h]pyrene (I), 4,11-diazadibenzo[a,h]pyrene (II) and 7,14-diazadibenzo[a,h]pyrene (III). These compounds were dispersed in paraffin disks and subcutaneously implanted in rats. Each experimental group consisted of 30 animals. The number of sarcomas induced by (I) and (II) was 23 and 16 respectively. The compound (III) has proved wholly inactive. Tumorigenicity of (I) and (II) was found to be proportional to their electron donation and inversely proportional to their electron acceptance in the performed polarographic test. Inactivity of (III) is being discussed from the aspect of molecular geometry.

Carcinogenicity and polarographic behavior of dibenz[a,h]anthracene, dibenz[a,h]acridine and dibenz[a,h]phenazine.

In a simultaneous test of carcinogenicity the authors have studied the activities of dibenz-[a,h]anthracene, dibenz[a,h]acridine and dibenz-[a,h]phenazine. These compounds were dispersed in paraffin disks and subcutaneously implanted in rats. Each experimental group consisted of 30 animals. The number of sarcomas induced by the above-mentioned compounds was 20, 5 and 3 respectively. Tumorigenicity of the aza analogues of dibenz[a,h]anthracene was proportional to their electron donation and inversely proportional to their electron acceptance in the performed polarographic test. The authors discuss the possibilities of using polarography as a screening test for the exclusion of carcinogenic polycyclic compounds.