Ultrahot electron formation under excess electron drift through solid Xe

The formation of "hot" (8 eV) electrons under excess electron drift in a moderate electrostatic field through solid xenon has been experimentally proved by observation of secondary electrons emitted from the photocathode. At T=77 K and U=1000 V one drifting electron produces about 20 (172 nm) photons, the efficiency of electric field-to-vacuum ultraviolet emission conversion is 15% tending to grow with temperature. A self-sustained electric discharge has been generated in solid Xe using a three-electrode cell with a zinc cathode.

Regulating and assessing risks of cholinesterase-inhibiting pesticides: divergent approaches and interpretations

This document presents a revised framework for conducting worker and dietary risk assessments for less-than-lifetime exposures to organophosphate or carbamate pesticides based on red blood cell (RBC) or brain acetylcholinesterase (AChE) inhibition or the presence of clinical signs and symptoms. The proposals for appropriate uncertainty factors are based on the biological significance of the cholinesterase (ChE) inhibition noted at the lowest-observed-effect level (LOEL) and the degree of uncertainty in the extrapolation between human and animal data. An extensive evaluation of industry data, not previously summarized, and the available literature indicate that the following risk assessment principles are supportable and protective of human health: Plasma ChE inhibition is not an adverse effect, and therefore should not be utilized in risk assessments. Red blood cell AChE is not associated with the nervous system and inhibition is not per se an adverse (neurotoxic) effect. When available, cholinergic effects or brain AChE inhibition data should take precedence over RBC AChE for determining no-observed-effect levels (NOELs). When available, human RBC AChE inhibition or cholinergic effects data should take precedence over animal data for determining NOELs. Due to the lack of adversity associated with inhibition of RBC AChE, the use of a 10-fold (10x) uncertainty factor from the NOEL is adequate when RBC AChE inhibition data from either animal or human studies are used to assess human risk. Due to greater potential for adversity, NOELs for brain AChE inhibition and cholinergic effects identified in animal studies should receive a default uncertainty factor of 100x; lower uncertainty factors may be used on a case-by-case basis. NOELs based on cholinergic effects noted in human studies should only require a 10x uncertainty factor, since an interspecies extrapolation factor from animals to humans is unnecessary. For RBC and brain AChE activity the threshold for defining a NOEL should be less than or equal to 20% difference from control activity in all species. For risk assessment purposes, duration and route of the study should reflect the expected duration and route of exposure for humans (i.e., a 21-d or 28-d dermal study for subchronic occupational dermal exposure assessment). When dermal data are not available, a subchronic oral toxicity study and an appropriate dermal penetration factor should be used. A general default of 10% absorption should be used, analogous to the United Kingdom and German exposure models that are widely used in Europe. The recommendations in this document are generally consistent with current risk assessment procedures used by Canada, the European Community (EC), and the United Kingdom (UK).

Induction of gastrointestinal tumors in mice fed the fungicide folpet: possible mechanisms

Dietary administration of the fungicide folpet, N-(trichloromethylthio) phthalimide, to B6C3F1 mice at dose levels of 1,000, 5,000 and 10,000 ppm induced a dose-related appearance of duodenal atypical hyperplasia, adenomas and adenocarcinomas. The appearance in some of these animals of gastric papillomas and gastric squamous cell carcinomas was correlated in many instances to the presence of duodenal obstructions. It is suggested that the gastric lesions appeared subsequent to, and as an indirect result of, these partial lumenal duodenal obstructions. We suggest that the presence of duodenal obstructions is consistent with the notion that reflux of folpet, bile acids and pancreatic enzymes into the stomach may have acted to irritate and consequently stimulate local neoplastic proliferation. In addition, the duodenal obstructions may have resulted in delayed emptying time of the stomach contents with consequential stagnation. This would cause high concentrations of folpet to act locally on the gastric mucosa.

Quantitative evaluation of chlortoluran-induced splenic hemosiderosis by means of an image analyzer

This study investigated a technique for the quantification of hemosiderin layed down in the spleen. The model used was the rat to which the urea-based herbicide chlortoluran was fed for 90 days. There was good correlation between hematological, biochemical, histological and image analytical techniques when splenic hemosiderosis was of a moderate to severe degree. Where hemosiderosis was of a slight nature, only the technique of image analysis was able to detect the on-going changes.

Chronic toxicity and carcinogenicity evaluation of fenvalerate in rats

Groups of 93 male and 93 female Sprague-Dawley rats were fed diets containing 1, 5, 25, and 250 ppm fenvalerate for up to 2 yr. The control group consisted of 183 males and 183 females. Approximately 10 treatment and 20 control rats/sex . group were killed at intervals of 3, 6, 12, and 18 mo. When body weights, food consumption, hematology, clinical chemistry and organ weights did not reveal a treatment effect, two additional groups of 50 males and 50 female rats were placed on 0 or 1000 ppm fenvalerate diets and maintained for 2 yr. Body weight was decreased and organ/body weight ratios were increased in brain, liver, spleen, kidneys (females), heart (females), and testes (males) in the 1000 ppm group. Mammary and pituitary tumors were commonly observed, along with a variety of other tumors occurring randomly among all control and treatment groups. No statistically significant differences in the number and type of neoplasms were observed except for mammary tumors in females in the main study. These effects were judged not to be toxicologically significant, since mammary tumor incidences did not exceed expected incidences in aged female Sprague-Dawley rats, time to tumor appearance was unchanged, and no shift in percent benign versus malignant tumors occurred. Sarcomas identified in the subcutis and dermis in 5/51 1000-ppm-treated males were also identified in 2% (1/50), 2% (2/102), and 0-6% of concurrent, original, and historical controls, respectively. Microscopic examination did not reveal any treatment-related lesions. The no-observable-effect level was determined to be 250 ppm.

Oxypertine in combination with imipramine: a controlled trial

A method for the controlled assessment of two agents for possible interaction in the treatment of endogenous depression is described. This consisted of dose-ranging the supplementary agent (oxypertine 30 mg and 60 mg daily or matching placebo) during Week 2 to Week 6 having established all patients on a therapeutic dose of imipramine during Week 1. The reported enhancement of imipramine by oxypertine was not confirmed.

Blood groups of pygmy chimpanzees (Pan paniscus): human-type and simian-type

Blood grouping of nine pygmy chimpanzees revealed them to be human-type group A1, M,Rho, and simian-type V.D, CCef, g, H, I, K, L. Only group Nc was polymorphic. Pan paniscus red cells can be easily distinguished from those of Pan troglodytes by the serological characteristics of human-type blood groups A and M. Also, the distribution of the simian-type blood group systems V-A-B and C-E-F are strikingly different in the two species.

Family studies on the simian-type blood groups of chimpanzees

Family studies were carried out the investigate the genetics of the chimpanzee simian type blood group systems V-A-B-D and C-E-F. In addition to providing new data, the studies confirm the validity of earlier results obtained by population genetics methodology for deducing genetic mechanisms in primate animals where family material cannot be obtained.

Blood group homologues in orangutans and gorillas of the human Rh-Hr and the chimpanzee C-E-F systems

In a previous study on homologues of the human Rh-Hr types in apes, weak agglutination of orangutan red cells by human anti-Rho and anti-hr’ sera was observed. Lack of adequate amounts of orangutan red cells needed for absorption experiments did not allow to ascertain whether the weak reactions were due to variants of the Rho and hr’ factors on orangutan red cells or to anti-species (species-specific) agglutinins against orangutan red cells in the human typing sera. The present experiments indicate that homologues of the human blood factors Rh0 , hr’ as well as rh’, rh” and hr” are lacking in orangutan red cells which are, therefore, comparable to the human Rh null red cells. In the search for homologues of chimpanzee C-E-F blood groups in other ape species, tests on 15 gorillas disclosed the presence in gorillas of polymorphism for Cc and Fc, while cc, antithetical to Cc in chimpanzees, as well Ec were both found to be absent from gorilla red cells.

The demonstration of human Gm-like serum -globulin types using nonhuman primate reagents. I. Experiments with anti-gibbon globulin serums

An antiglobulin serum was prepared by immunizing rabbits with serum globulin of gibbons. This reagent was used for an inhibition test with rhesus monkey red cells coated with rhesus isoantibodies or baboon red cells coated with isoantibodies as indicator. With this test individual differences could be demonstrated in human γ-globulins comparable to the Gm types.

Serial EEG studies in presenile dementia

Longitudinal EEG studies in primary presenile dementia are conspicuously lacking (Kiloh and Osselton, 1966). Letemendia and Pampiglione (1958) found no changes, over a one year period, in the EEG patterns of several of their patients with Alzheimer's disease. Attention has recently been drawn to the relevance of duration of the particular illness when interpreting EEG data in primary presenile dementia (Gordon and Sim, 1967). The tendency to non-specificity of such data in this group of diseases underlines the importance of chronological variations in the EEGs, with regard to both differential diagnosis and prognosis.

Mentally ill West Indian immigrants

At present there exist in the literature numerous references to mental illness in different cultures; these vary from consideration of disorders peculiar to certain cultures, e.g. Koro, Latah, Amok, Wihtigo, etc., well reviewed by Yap (Yap, 51) to the problems of acculturation and mental illness. Examples of the latter include the studies of Tooth and Carothers, the latter suggesting that Westernization and detribalization increased the incidence of psychosis in Africans (Carothers, 2; Tooth, 45). Slotkin (42) pointed to the paranoid schizophrenia phenomena among acculturated Menomini. Hallowell (14, 15) found significant Rorschach differences between acculturated and unacculturated Salteaux.