Thermal motion and energetics of self-assembled domain structures: Pb on Cu(111)

Low energy electron microscope measurements of the thermal motion of 50-200 nm diameter Pb islands on Cu(111) are used to establish the nature and determine the strength of interactions that give rise to self-assembly in this two-dimensional, two-phase system. The results show that self-assembled patterns arise from a temperature-independent surface stress difference of approximately 1.2 N/m between the two phases. With increasing Pb coverage, the domain patterns evolve in a manner consistent with models based on dipolar repulsions caused by elastic interactions due to a surface stress difference.

Nanostructures. Self-assembled domain patterns

The ordered domain patterns that form spontaneously in a wide variety of chemical and physical systems as a result of competing interatomic interactions can be used as templates for fabricating nanostructures. Here we describe a new self-assembling domain pattern on a solid surface that involves two surface structures of lead on copper. The evolution of the system agrees with theoretical predictions, enabling us to probe the interatomic force parameters that are crucial to the process.

High and low luminance letters, acuity reserve, and font effects on reading speed

We compared reading speed with two fonts, Dutch (serif) and Swiss (sans serif). Text was displayed on a computer monitor, white letters on black, with the RSVP method. Luminance of the letters was either 146.0 or 0.146 cd m-2. Lower-case x-height of the fonts was approximately 5.5 times as large as letter acuity. At the high luminance, there was no difference between reading rates. There was a significant advantage for the Swiss font at the low luminance. The acuity reserve for Swiss was higher than for Dutch at the low luminance, which may account for the difference in reading speeds.

Text Font Affects Reading Speed at a Low Luminance but Not at a High Luminance

We are beginning a series of studies in which we shall investigate which characteristics of text fonts may be successful in allowing text to be read with different kinds of degradations that may be experienced by low-vision patients. As a first attempt to simulate one of the problems that certain patients might have, we measured reading speeds with two proportionally spaced fonts at a high photopic luminance (146 cd m−2) and at a very low luminance (0.146 cd m−2). We used the RSVP (rapid serial visual presentation) reading method, which eliminates the need for scanning eye movements. The two fonts were ‘Swiss’, a simple sans-serif font, and ‘Dutch’, a serif font similar to Times Roman, both presented at the 20/80 size; letters were white on black, with a contrast of 0.94. Subjects were young, normally sighted high-school and optometry-college students. The reading speed results from 47 subjects were as follows, for four conditions: high luminance, Swiss 531 and Dutch 540 words min−1; low luminance, Swiss 479 and Dutch 429 words min−1.

At the high luminance, there is no significant difference between reading rates. There is a significant advantage for the Swiss font at the low luminance: p=0.005.

There may be a significant difference in reading speed with different fonts when the patient's perceptions are degraded by disease and/or aging processes. Other parameters to be investigated with this method include contrast, size, blur, and visual field position. The simulation results will suggest parameter values to test on low-vision patients.

Effects of glucosinolate breakdown products on the hepatic biotransformation system in male rats

The effects of 5-vinyloxazolidine-2-thione (VOT), 1-cyano-3-butene (CYB) and various isothiocyanates on parameters of hepatic phase I and phase II biotransformation were investigated in male rats after oral treatment for 3 consecutive days. The compounds with the exception of CYB caused increases in liver weight and glutathione S-transferase activity. Cytochrome P-450 level and monooxygenase activities were decreased by the isothiocyanates and CYB. Administration of VOT resulted in contrasting response of monooxygenases: reduced aminopyrine N-demethylation and enhanced aniline hydroxylation. Possible mechanisms were discussed.

Toxicological evaluation of rapeseed products in a subacute feeding study in rats

Groups of 15 male rats were fed ad libitum for 4 weeks standard diet containing 0, 2.5, 5 or 10% rapeseed protein isolate (RPI), 2.5, 5 or 10% rapeseed extraction residue (RER) or 10% casein. Body weight gain and food intake were recorded weekly. Clinical chemistry analyses, haematology, urinalysis, organ weights and histology were performed terminally. Serum alanine aminotransferase was decreased by RPI, RER and casein, while serum albumin only increased in rats fed RER. Microscopic examinations revealed abnormalities in liver and kidneys of animals at the 10% RPI, RER and casein levels. The absolute liver weights showed increases in the 5 and 10% RER groups and in the 10% RPI group. The relative kidney weights were reduced at all RER levels and in the 2.5% RPI group. Antithyroid activity of the rapeseed products were not noted.

Subacute oral toxicity study of benzyl isothiocyanate in rats

The subacute toxicity of benzyl isothiocyanate (BITC) was investigated in male rats given oral doses of 0, 50, 100 and 200 mg/kg body weight/day for 4 weeks. Body weight gain and food consumption were decreased with increasing doses of BITC. Haematological changes of toxicological relevance were observed in the highest dose group. BITC administration resulted in increased serum cholesterol level in all treatment groups and decreased serum triglycerides level at 200 mg/kg. Renal dysfunction was indicated by reduced urine volume, proteinuria and enhanced urinary lactate dehydrogenase activity. BITC exposure also affected the weights of various organs and caused histological changes in the ductus choledochus, liver, ileum and mesenteric lymph nodes.

[Toxicologic evaluation of sucrose carbonic acid esters in basic subchronic feeding studies in rats. 2. Effect of sucroacetoglycerides]

Groups of male and female rats received a sucroacetoglycerides containing product (SAG) for 3 months at dietary levels of 0, 2.5, 5 and 10%. Food consumption was initially increased in females at all SAG-levels. After two weeks significant increases in food intake were observed in males and females fed 10% SAG throughout the feeding period. The serum analysis revealed significantly elevated activity in serum alkaline phosphatase at the highest SAG-level in males and females after 6 weeks and in females after 13 weeks. Histological changes related to the SAG-feeding were noted in the intestinal lymph nodes of male and female animals fed 10% SAG. The no-adverse effect level established in this subchronic feeding study was 5% SAG in the diet of rats, equivalent to a daily intake of 3.6 g/kg body weight in males and 4.0 g/kg in females.

[Toxicological effect of a fatty acid mixture in rats]

The effects of a fatty acids mixture containing nearly 50% odd numbered fatty acids (PC-Säure) were studied in a subchronic toxicity test in male and female rats. The animals received PC-Säure in their diet at levels of 0, 1.25, 2.5 and 5% for 13 weeks. Food intake was increased at 5% PC-Säure level in males. Food efficiency was initially decreased in males and females of this group. Ingestion of PC-Säure resulted in increases of the urine volume and the urinary lactate dehydrogenase activity in both sexes. Male and female rats fed PC-Säure showed elevated serum activities of alkaline phosphatase and leucine aminopeptidase and decreases in serum cholesterol and triglycerides. Dietary PC-Säure elevated the serum creatinine content in males at the two highest levels. A transitory increase in the activity of the serum alanine aminotransferase was observed in females fed 5% PC-Säure. Increased liver and kidney weights were found in both sexes.

[Toxicological evaluation of saccharose carbonic acid esters in basic subchronic feeding trials with rats. 1. Effect of saccharose fatty acid polyester]

Groups of male and female rats received a sucrose fatty acid polyesters containing product (SPE) in their diet for 13 weeks at levels of 0, 5, 10 or 15%. Additional groups were pair-fed to the high-dose SPE-group (standard diet, 92.5%) or given food containing 7.5% hydrogenated lard (HF) or 4.5% fatty acid ethyl ester (FEE). Compared to the controls, there were increases in the food intake in males and females of the SPE-groups, HF- group and FEE-group. Male rats fed SPE showed increases in serum urea nitrogen at all levels, in serum alkaline phosphatase activity and urinary glucose excretion at 10 and 15%, in serum leucine amino-peptidase at 15%. In females dietary SPE increased the blood glucose content and serum alkaline phosphatase activity at 15% and the serum leucine aminopeptidase activity at 10 and 15%.

[The subacute toxicity of glucosylthiazolidine-4-carbonic acid in rats]

Glucosylthiazolidine-4-carbonic acid, an intermediate of the Maillard reaction between D-glucose and L-cysteine, was given in doses of 0, 25, 50 or 100 mg/kg b.w. by oral intubation to male and female rats for 21 days. General appearance, growth, food consumption, haematology, urine analysis and serum chemistry including determinations of enzyme activities, organ weights and macroscopic and microscopic pathology were used as criteria for adverse effects. Effects on the kidneys were indicated by oliguria and decreased specific gravity of the urine in males and histopathological changes of the proximal tubules in females. The no-effect dose established from this study is 25 mg/kg b.w.

[Distribution and metabolism of azoxybenzene in the rat]

No sex differences could been shown after absorption and distribution of azoxybenzen in the rat. The highest level occur in the thyroid gland, the adrenals and in the fat tissues. The maximum level was reached 30 min. after application.

[The subchronic toxicity of 5-vinyloxazolidine-2-thione in rats]

Groups of male and female rats received 5-vinyloxazolidine-2-thione (VOT) in their drinking water for 13 weeks at concentrations of 0, 10, 25, 50 or 100 mg/l and 0, 2.5 or 5 mg/l respectively. Compared with the controls, there were decreases in food intake and growth of females given VOT-doses of 10 mg/l and higher. Liquid intake was reduced in males and females of the highest dose group. Terminal haematological examination revealed an increase in white cell count at the 50 and 100 mg levels in females and a reduction in the red cell count at 100 mg/l in males. Organ weight changes were dose-related increases in the relative thyroid and liver weight and a decrease in the relative thymus weight. Structural and functional changes of the thyroid were observed in animals at levels of 10 mg/l and higher. Histological examinations of the kidneys showed tubulonephrosis in animals at and above a VOT-level of 5 mg/l. The no-observed-effect level (NOEL) established from these studies was 2.5 ml VOT/l drinking water (approximately equivalent to an daily intake of 0.4 mg/kg body weight).

Effect of allyl isothiocyanate on hepatic monooxygenases and serum transferases in rats

The effect of allyl isothiocyanate (AITC) on the activities of liver monooxygenases and serum transferases was investigated in male rats. AITC was given in oral doses of 0, 50, 100 or 150 mg/kg bw for 3 consecutive days. Increased relative liver weights and decreased activities of hepatic aminopyrine-N-demethylase, p-nitroanisole-O-demethylase and aniline-p-hydroxylase were observed in all treatment groups. The administration of AITC at dose levels of 100 and 150 mg/kg caused a statistically significant increase in the serum aspartate aminotransferase activity.

Short-term toxicity study of allyl isothiocyanate in rats

Allyl isothiocyanate (AITC) was given in doses of 0, 10, 20, or 40 mg/kg (5 days/week) by oral intubation to male rats for up to 6 weeks. The highest dosage level caused a decrease in body weight, thymus weight, blood glucose and serum globulin levels. Haematological examination revealed an increased percentage of neutrophils and a decreased percentage of lymphocytes after treatment for 2 weeks. Increased liver and adrenal weights were found in all test groups. Renal dysfunction was indicated by increased urinary aspartate amino-transferase activity, reduced urine volume and changes in the specific gravity of the urine. Histopathological changes were observed in the kidneys of animals at dosages of 20 and 40 mg/kg and in the livers of animals at the highest dosage level.

[The effect of ethylenethiurea on hematopoesis in rats]

The influence of single and repeated oral administration of ethylenethiourea (ETU) on hematologic parameters of the peripheral blood and the bone marrow was studied in male and female rats. Effects of single treatment on the erythrocytic system were initially indicated by increase in red blood cell count, hemoglobin concentration and hematocrit of the peripheral blood. The initial polyglobulia was followed by a decrease in the blood hemoglobin concentration and the number of erythroblasts of the bone marrow. Continuous administration of ETU resulted in hyporegenerative anemia. The white blood picture showed leukopenia after single and continuous administration of the substance. This effect resulted from a decline in lymphocyte numbers which occurred both in the peripheral blood and in the bone marrow. The hematologic changes were induced with 50 mg ETU/kg body weight and more using single treatment and 600 ppm (= 70 mg ETU/kg body weight) and more under dietary administration.

[The effect of azoxybenzene on microsomal liver enzymes in the rat]

Oral administrations of azoxybenzene (0, 25, 50 and 100 mg/kg b.w.) over a period up to 7 days caused a time and dose dependent decrease in the amount of cytochrome P-450 as well as in the ability of aminopyrine-N-demethylation and aniline hydroxylation in the hepatic microsomes of male and female rats. In both sexes there were retardations in the body weight gain and increases in the relative weight of the liver. The amount of the microsomal cytochrome b5 was increased.

Activation of leukocytes during prolonged physical exercise

Previous studies have demonstrated an increment of circulating leukocytes and enhanced secretion of interleukin-1 by monocytes and macrophages during physical exercise. In the present study the effect of physical exertion on the activity of polymorphonuclear (PMN) leukocytes was investigated. Following both short-term (running 2,000 meters) and long-term (running 10,000 meters) exertion, phorbol-stimulated chemiluminescence, as an indicator of leukocytic oxygen radical formation and release of leukocytic elastase, as a parameter of degranulation, were determined immediately after running. The number of circulating leukocytes increased both after short-term (+21%) and long-term (+61%) exercise. There was a minor release of PMN elastase following short-term activity causing plasma levels of this compound to rise from 100 +/- 4.0 ng/ml to 116 +/- 12.3 ng/ml. Long-term exercise, on the other hand, induced a significant increase of elastase plasma levels from 107 +/- 9.1 ng/ml to 300 +/- 23.4 ng/ml, suggesting a remarkable release of this proteinase from neutrophils. Based on these findings we conclude that during physical exercise degranulation of PMN leukocytes occurs. Moreover, the fact that phorbol-stimulated chemiluminescence is decreased after running demonstrates an impaired capability of white cells to generate oxygen radicals.

[The enzymatic degradation of DDT. 6. The fate of the DDT metabolites dichlorodiphenyldichloroethylene and dichlorodiphenylmonochloroethylene in the rat]

DDE is hydrogenated in the rat organism. The distribution of the compound is described. DDMU is degradated to DBP as well as transformed to DDA and DDOH. Excretion and distribution are studied.

Transluminal closure of patent ductus arteriosus: long-term results of 208 cases treated without thoracotomy

Patent ductus arteriosus was the first inborn cardiac defect ever eliminated by percutaneous transvascular therapy. The method, results, and complications of Ivalon plugging of the ductus in 208 patients between 5 and 62 years old and treated between 1967 and 1985 are described. Permanent closure was accomplished in 197 patients (94.7%). The following particular benefits are obtainable from the method: no need for thoracotomy; local anesthesia applicable to 65% of all cases; 30 mm average time of intervention; only moderate invasiveness to the patients; only 7 days of hospitalization; good cost-benefit ratio.

[Comparison of the distribution and toxicity of alpha-, beta-, and gamma-hexachlorocyclohexane (HCH) following 30 days of administration to rats]

Administration of 1000 ppm alpha-HCH, 600 ppm beta-HCH and greater than or equal to 125 ppm gamma-HCH to rats caused a growth retardation. alpha-HCH and beta-HCH led to livermass enlargement. beta-HCH caused a decrease of absolute brain-mass. In case of alpha-HCH and gamma-HCH fat tissue, kidneys and adrenals had a high burden in residues. Fat tissue and adrenals had high residues of beta-HCH. The level of HCH-residues during the test period was gamma much less than beta less than alpha. The results are discussed taking into account the contradictory knowledge from literature.

[The enzymatic degradation of DDT. 3. Metabolism of DDT]

DDT orally given to rats is converted into DDD by reductive dechlorination in the liver within 30 min. 6 h after a single application of 10 mg DDT per rat a quantity of 60 mg DDD/kg was indicated in the liver. DDT is stored in the adrenal glands; in the other organs an equilibrium comes up obviously, even with further application. The quantitative ratios are reported. Information on the experimental details of DDT determination and--anticipatory to the following publications--on the analysis of the most relevant metabolites is given.

Contrasting effects of ethylenethiourea on hepatic monooxygenases in rats and mice

The effects of ethylenethiourea (ETU) on the hepatic xenobiotic metabolizing system in rats and mice were investigated. Male rats and male mice were given oral doses of 50 and 75, or 50, 75, 100, 500, and 1,000 mg/kg for 3 days. The microsomal enzymes studied were aminopyrine N-demethylase, aniline hydroxylase, and cytochrome P-450. In rats, the activity of aminopyrine N-demethylase was reduced to values between 60 and 70% of controls 24 h after treatment. A decrease in aniline hydroxylase activity and cytochrome P-450 content was observed on the 3rd day after exposure. In mice, treatment with ETU resulted in an increase of cytochrome P-450 at all dose levels. The activity of aniline hydroxylase was significantly elevated in the groups receiving doses of 100 mg/kg and higher. Aminopyrine N-demethylase was unaffected by the treatment. The results suggest that there are qualitative differences between rats and mice after ETU exposure with respect to the response of the hepatic mono-oxygenases.

[Transformation reactions of special metals in organisms and in the environment. 3. In vivo reactions between mercury II chloride and monomethyltin trichloride in rats]

Following the comments on the metabolism and the toxicity of methylmercury compounds as well as on the interaction with food components and a few environmental chemicals from literature study, the results of the in vivo experiments for examining the reaction between HgCl2 and CH3SnCl3 in the gastrointestinal tract and the subsequent distribution of the formed methylmercury are reported. The reaction between both of the substances proceeding in aqueous solution with immediate formation of methylmercury also leads in the intestinal tract very rapidly to the formation of methylmercury and its distribution into various organs. An increase in the relative weight of liver and kidneys was evident.

[Effect of allyl isothiocyanate on cytochrome P-450 of rat liver microsomes]

The thrice-repeated oral administration of graded doses (50, 100 and 150 mg/kg of body mass) of allyl mustard oil to rats resulted in a decrease of the cytochrome P-450 and cytochrome b5 contents of the liver microsomes. There occurred a dose-dependent increase in mass of this organ.

[Significance and importance of enzyme diagnosis in the framework of toxicological studies of plant protectives, pesticides and agents for biological process control]

In toxicological experimentation, clinico-chemical and biochemical data are increasingly involved in the comprehensive evaluation of adverse effects of plant protectives, pesticides and agents for the biological process control on the mammalian organism. Blood serum and urine or organic homogenates from experimental animals kept under standardized conditions are chiefly used for enzymodiagnostic analyses. Changes in enzyme activity occurring under the influence of the bioactive test substances must be regarded as indicative of direct effects on the biocatalyst, metabolic changes or impairments of certain organs.

[Synergism of selected pesticides. 1. Acute oral toxicity in combined administration]

Comparative studies with male rats were performed to investigate the coergism of single oral doses of selected pesticides, the comparison being based on the lethal effects observed. The quantitative analysis of the dose-mortality relationship and the determination of the coergistic index evidenced a slight increase of the lethal effect with lindane-phosmet and lindane-carbaryl combinations. The combined administration of lindane and ethylenethiourea resulted in an additive lethal effect.