Two Weeks Inhalation Exposure to 4-terf-Butyltoluene Causes Persistent Changes in Visually Evoked Potentials in Rats

Abstract: The effects of repeated exposure to 20 p.p.m. 4-tert-butyltoIuene (CAS No. [98-51-1]) 6 hr/day for 14 days on the function of the intact nervous system were examined by measurements of flash evoked potentials in Wistar rats. The exposure to 4-tert-butyltoluene induced changes in the amplitudes of the flash evoked potentials. The changes were significantly different from controls on day 2, 19 and 26 after cessation of the exposure, but not on day 5 and 12. No significant difference in body weight gain between groups was found during the experiment. These results indicate that repeated exposure to 20 p.p.m. 4-tert-butyltoluene causes persistent changes in the function of the central nervous system measured as changes in the flash evoked potential. A reevaluation of the present TLV-value of 10 p.p.m. for 4-tert-butyltoluene is suggested.     

Bone mineral density of the proximal tibia following uncemented arthroplasty

Bone mineral density (BMD, g/cm2) was measured using dual-photon absorptiometry (DPA) in selected areas of the proximal tibia following uncemented PCA knee prosthesis. In nine patients with 14 alloplastic operations, measurements were taken at 3-6-month intervals for the first 3 1/2 years after operation. There was a significant increase in BMD of about 15% during the first 6 months after operation. The following year it remained increased, although not significantly, compared with the initial values, then gradually diminished. Increased bone density after arthroplasty may be explained mainly by stimulation of bone formation from weight bearing due to improved walking ability. Stress shielding of the proximal part of the supporting tibial bone did not seem to occur.     

Reduced breast cancer mortality among fishermen's wives in Norway

International comparisons show that populations having a high consumption of fish experience low incidence of breast cancer. We compared death rates from breast cancer among socioeconomic groups in a prospective study of 533,276 Norwegian women aged 35–54 years who were followed from 1970 through 1985. Compared with the reference group (wives of unskilled workers) the fishermen's wives had a decreased risk of breast cancer with a relative risk (RR) of 0.67 (95% confidence interval [CI]=0.47–0.94) adjusted for age and the number of children. Among fishermen's wives who were parous, adjustment for age at first birth gave an RR of 0.62 (CI=0.43–0.91). This study supports the hypothesis that certain aspects of diet, i. e., fish consumption, may be associated with lower breast-cancer mortality.Drs Lund and Bønaa are with the Institute of Community Medicine, University of Tromsø, Tromsø, Norway. Address correspondence to Dr Lund, Institute of Community Medicine, University of Tromsø, N-9037 Tromsø, Norway.     

Comparison of allergenicity and immunogenicity of an intact allergen vaccine and commercially available allergoid products for birch pollen immunotherapy

BACKGROUND: Specific immunotherapy with intact allergen vaccine is a well-documented treatment for allergic diseases. Different vaccine formulations are currently commercially available, the active ingredient either being intact allergens or chemically modified allergoids. The rationale behind allergoids is to decrease allergenicity while maintaining immunogenicity. However, data from the German health authorities based on reporting of adverse events over a 10-year period did not indicate increased safety of allergoids over intact allergens. OBJECTIVE: The objective of this study was to investigate the effect of chemical modification on allergenicity and immunogenicity comparing four commercial allergoid products for birch pollen immunotherapy with an intact allergen vaccine. METHODS: Solid-phase IgE inhibition and histamine release assays were selected as model systems for allergenicity, and a combination of human T cell proliferation and IgG titres following mouse immunizations were used to address the immunogenicity of the intact allergen vaccine and the four allergoids. In all assays, the products were normalized with respect to the manufacturer's recommended maintenance dose. RESULTS: IgE inhibition experiments showed a change in epitope composition comparing intact allergen vaccine with allergoid. One allergoid product induced enhanced histamine release compared to the intact allergens, while the other three allergoids showed reduced release. Standard T cell stimulation assays using lines from allergic patients showed a reduced response for all allergoids compared with the intact allergen vaccine regardless of the cell type used for antigen presentation. All allergoids showed reduced capacity to induce allergen-specific IgG responses in mice. CONCLUSION: While some allergoids were associated with reduced allergenicity, a clear reduction in immunogenicity was observed for all allergoid products compared with the intact allergen vaccine, and the commercial allergoids tested therefore do not fulfil the allergoid concept.     

Local circuit neurons of macaque monkey striate cortex: I. Neurons of laminae 4C and 5A

A study has been made, using Golgi preparations, of the organization of neurons with smooth or sparsely spined dendrites, here called local circuit neurons, of the macaque monkey primary visual cortex. Since these neurons include those responsible for inhibitory circuitry of the cortex, a better understanding of their anatomical organization is essential to concepts of functional organization of the region. This account describes those neurons found with cell body and major dendritic spread within the thalamic recipient zone of lamina 4C and its border zone with lamina 5A. The neurons are grouped firstly in terms of in which laminar division the soma occurred--4C beta, 4C alpha or the border zone of 5A-4C beta--and secondly, into varieties on the basis of the interlaminar projection patterns of their axons. Most, if not all, of the local circuit neurons of these divisions have interlaminar axon projections as well as an arbor local to their cell body and dendritic field. These interlaminar projections are highly specific, targeting from one to five laminar divisions depending on the variety of neuron; on this basis 17 varieties of local circuit neuron are described. While the number of varieties appears dauntingly large in terms of understanding the functional circuitry of the region, the clear-cut organization of the interlaminar links may provide clues as to the information processing that concerns each neuron. The local circuit neuron axon projections can be related to a wealth of information already available concerning the laminar organization of afferent axons and efferent cell groups, the organization of spiny neuron intrinsic relays (presumed to be excitatory), and physiological properties of different laminar divisions. It is hoped that the information derived from this study can serve as a guide for correlated physiological-anatomical studies on single cells of the region.     

The use of post-embedding immunoelectron microscopy in the diagnosis of glomerular diseases. Comparison of immunoelectron microscopic and immunofluorescence studies.

Fifty renal biopsies were studied by immunoelectron microscopy after embedding in a partly hydrophilic polyacrylic resin (LR White). Immunofluorescence studies were carried out on frozen sections of parallel tissue samples. Polyacrylic embedding gave good preservation of the renal ultrastructure and precise localization of immunoglobulin and C3c antibodies within glomerular electron-dense deposits. Non-specific staining of plasma proteins within vascular lumina could easily be detected. There was good correlation between immunoelectron and immunofluorescence microscopy. Immunoelectron microscopy is a very sensitive method, which can detect small amounts of antigen. More cases were, however, positive by immunofluorescence than by immunoelectron microscopy. This discrepancy may be explained by difference in sample size, and by difference in resolution of morphological details (electron microscopy versus fluorescence microscopy).