Long-term exposure to jet fuel. II. A cross-sectional epidemiologic investigation on occupationally exposed industrial workers with special reference to the nervous system.

Thirty jet fuel exposed workers selected according to exposure criteria and thirty nonexposed controls from a jet motor factory were examined, with special reference to the nervous system, by occupational hygiene physicians, psychiatrists, psychologists, and neurophysiologists. The controls and the exposed subjects were matched with respect to age, employment duration, and education. Among the exposed subjects the mean exposure duration was 17 years, and 300 mg/m3 was calculated as a rough time-weighted average exposure level.

Influence of the pulpal route on uptake of 45Ca in enamel and dentin of developing rat molars.

45Ca uptake in developing enamel and dentin was studied by autoradiography. The findings indicate that the pulpal route does not supply significant amounts of calcium to the rapidly mineralizing enamel. Disruption of the odontoblastic layer did not seem to result in altered penetration of calcium into the dentin in a manner similar to that described for disruption of the matrix secreting cell layer of enamel and of bone.

In vivo and in vitro study of 59Fe uptake in developing rat molars.

Autoradiographic methods were used to study 59Fe uptake in vivo in mineralizing tissues of young rats. Localization of 59Fe was observed in the ameloblastic layers of molars. In vitro studies were performed which demonstrated that 59Fe uptake in developing rat molar enamel was limited by the metabolic activity of the cells of the enamel organ.

Comparison of 33P with 45Ca distribution in developing rat molar enamel in vivo and in vitro.

The distribution of 45Ca and 33P in developing rat molar enamel has been studied using freeze sectioning and autoradiographic methods. The distribution patterns of the two tracers in vivo were dissimilar. The use of in vitro methods showed that flux of 33P into enamel is not influenced by the cells of the enamel organ.

A method for evaluation of initial tissue response to biomaterials.

In the present paper an implantation technique is described whereby the effect of the surgical operation is eliminated and initial tissue reactions to materials may be studied. A teflon body was implanted intramuscularly in rabbits. After six weeks the overlaying tissue was excised and the implant removed.

In vitro study of cellular influence on 45Ca uptake in developing rat enamel.

The in vitro method for culture of molar teeth from eight-day-old rats, as reported in this study, appeared to sustain reasonably normal activity in the cells of the enamel organ and pulp through culture periods of four to eight hours. Inhibition of metabolic activity in the explants by addition of 5 mM iodoacetate or 2,4-dinitrophenol to the culture medium, or by heating at 70 C for 10 minutes, did not appear to affect the intensity or pattern of 45Ca uptake in the more advanced, rapidly mineralizing areas of the enamel. Neither did stripping of the enamel organ from the surface of the enamel have a demonstrable effect in those areas.

Operative treatment of ulnar nerve neuropathy in the elbow region. A clinical and electrophysiological study.

Thirty-three patients with ulnar nerve neuropathy due to a lesion in the ulnar groove were operated upon during a 5-year period. All the patients were analyzed preoperatively. One-third of the patients had a history of alcohol abuse.

Visible and non-visible EEG changes demonstrated by spectral parameter analysis.

A change of the heart rate in patients with complete AV-block and externally controllable cardiac pace-makers was earlier shown to influence cerebral function, as measured by psychological tests. To determine whether this influence manifests itself in the EEG, 9 patients aged 43-83 years were examined, all having complete AV-block and externally controllable pace-makers. Their EEGs were recorded at different heart rates between 40 and 100/min at rest and during a mental arithmatic test.

An in vitro method for toxicity evaluation of water-soluble substances.

The purpose of the present investigation was to develop a simple method for the evaluation of reversible and irreversible toxic influences in a cell culture system. A cell monolayer established on the bottom of glass scintillation vials was exposed to a toxic substance (phenol). Changes in the DNA synthesis of the cells were utilized as a criterion of toxic influence, and were measured by recording the incorporation of tritium labelled thymidine using a liquid scintillation technique.

Biologic tests of a proposed pulp capping agent (Reocap).

A calcium hydroxide-containing cement (Reocap) was tested with regard to its suitability as a pulp capping agent. The pulp of 34 monkey teeth was exposed and Reocap was applied to the pulp wound and the cavity floor, after which the cavities were filled with amalgam. The observation periods were 8 days (10 teeth) and 80 days (24 teeth).

An EEG simulator-a means of objective clinical interpretation of EEG.

In 1969 Zetterberg presented a method for describing the spectral properties of an EEG signal, starting from the assumption that the signal is essentially stationary during the analysis epoch. The method involves determination of the parameters for a model consisting of a lenear filter with the ability to produce a signal with the same spectral properties as the EEG signal. Zetterberg and Ahlin described in 1975 an analogue simulator based on this model theory.

Visual evaluation and computer analysis of the EEG--a comparison.

Spectral parameter analysis (SPA) of the EEG provides a description of the distribution of spectral power in the EEG signal in the form of a rational spectrum with not more than 8 parameters. The spectrum is divided into 1-3 components described by frequency and power parameters: bandwidth (delta), peak frequency (f) and power (G). These spectral parameters are determined with the aid of a computer.