Barium concentration in cast roe deer antlers related to air pollution caused by burning of barium-enriched coals in southern Poland.

Concentrations of Ba, Zn, Pb, Fe, and Mn were determined by atomic absorption spectroscopy in freshly cast antlers from male roe deer of different ages (2 to 4 years old and older than 4 years) collected in Balin near Chrzanów and in the vicinity of Zywiec, S Poland. Barium content ranged from 124 to 196 ppm (mean 165 ppm) in the Balin 12 samples and from 207 to 351 ppm (mean 287 ppm) in 3 antlers from Zywiec. The concentration of Ba was comparable to that of Zn (134-275 ppm, mean 169 ppm). Elevated concentrations of Ba in antlers most probably originated from direct uptake of airborne barite nanocrystals through the respiratory system and/or by digestion of barite-rich dust particles deposited on plants. Burning of Ba-enriched coals is regarded as the principal source of Ba in the investigated areas inhabited by roe deer. Increased concentrations of Ba in antlers from the Zywiec area compared to Balin reflect particularly high air pollution caused by coal-burning mostly for domestic purposes combined with an unfavorable topography that impedes efficient air circulation.

Radiation dose to the lens in sequential and spiral CT of the facial bones and sinuses.

A tendency for over-utilization of the radiological examinations of facial bones and sinuses has been observed. The radiosensitive lens is exposed to radiation during such examination. Comparison of routine roentgenography and spiral axial and coronal CT in sequential and spiral acquisition modes with different mAs values was undertaken using Alderson Rando Phantom. The spiral-CT technique with pitch 1.5 performed in the coronal plane gave the lowest radiation dose to the lens as compared with other CT methods and only seven times higher than routine sinus roentgenography.

Organ doses from cardiac and carotid digital subtraction angiography.

Estimates of mean organ doses from cardiac and carotid digital subtraction angiography (DSA) are obtained from measurements done using a Rando-Alderson tissue-equivalent phantom. Thermoluminescent dosemeter chips and discs were calibrated and used for all measurements in the primary and scattered radiation fields. Skin doses as well as mean doses received by the thyroid, lung, lens of the eye, breast, uterus and the ovaries were measured. A 30 degree right anterior oblique (RAO) cardiac DSA study produces a beam entrance dose of about 121 mGy at a rate of 0.48 mGy/frame. The highest mean organ dose from cardiac DSA was to the lung with a value of 14.4 mGy. The rest of the organs received doses below 1 mGy. In carotid DSA, the mean entrance doses resulted from the RAO, left anterior oblique, and the Towne's view projections give an average of 168 mGy at a rate of 8.4 mGy/frame. The highest mean organ dose from the three projections, 21 mGy, was received by the thyroid. The uterus and ovaries received the lowest doses from both procedures with values below 0.04 mGy. Patient and phantom surface exposures were compared using an exposure area product system. Hence, exposure conditions used for measuring organ doses on the phantom were adjusted to resemble those used for patients.

Activation of masked neural determinants in amphibian eggs and embryos and their release from the inducing tissue.

The neural-archencephalic (forehead) inducing activity of the microsomes and the high speed supernatant from Xenopus laevis ovaries and eggs was tested on gastrula ectoderm of Triturus alpestris. Both fractions have a very small inducing activity which increases considerably after autolysis or treatment with dissociating agents. A comparison with the inducing activity of the high speed supernatant from gastrulae suggests that neural inducing factors are synthesized in the ovary, stored in a masked form and activated, in part, during gastrulation. When the supernatant proteins from eggs and gastrulae were subjected to size-exclusion HPLC the neural inducing activity was eluted in different size classes, suggesting a limited proteolysis of a precursor during early embryogenesis. Further experiments have shown that treatment of the blastoporal lip from early Triturus gastrulae with actinomycin D or cycloheximide which inhibit the synthesis of RNA and protein respectively, diminishes the neural-archencephalic (forehead) inducing activity of the blastoporal lip. Treatment with actinomycin D or cycloheximide followed by ethanol, which, besides other structures, impairs the plasma membrane, does, however, not reduce the inducing activity. This may suggest that components which are needed for the transport of the neuralizing factor are diminished, when the synthesis of mRNA and protein is inhibited. Such components are probably needed for the release of the neuralizing factor from the blastoporal lip, the inducer tissue.

Covalent coupling of neuralizing factors from Xenopus to Sepharose beads: no decrease of inducing activity.

Two neural inducing factors extracted from Xenopus gastrulae, a basic protein from ribonucleoprotein particles and an acidic protein from the high speed supernatant were covalently bound to CNBr-Sepharose or cross-linked CNBr-Sepharose particles. The protein-Sepharose complexes cannot be taken up by the competent ectoderm cells, but both factors remain fully active. The inducing activity is not due to a release of the bound factors. The experiments suggest that both neural inducing factors act on the cell surface of the competent ectoderm cells.

Doses from occupational exposure: a study of radiation doses to workers in Kuwait over a four-year period.

The personal monitoring facility in the Ministry of Public Health's Radiation Protection Department has provided service to all users of ionizing radiation in medicine, research and industry in Kuwait. Exposure results during 1980-1983 were compared and analysed to examine the efficiency of protection measures adopted by each occupation. The results indicate that annual doses received by workers in different occupations in recent years tend to be generally low, but remain higher than those received by similar workers in other countries. Several overexposures to radiologists, radiology nurses, medical radiographers, and industrial radiographers increased the overall annual collective doses. As a result, protective measures designed for radiologists and nurses involved with special radiographical procedures should be improved. The recent use of the after-loading technique in intra-cavitary therapy was responsible for a significant reduction in the overall average doses received by workers involved in radiotherapy.

Ribonucleoprotein particles from Xenopus eggs and embryos. Neural-archencephalic-inducing activity of the protein moiety.

Ribonucleoprotein particles were isolated from unfertilized eggs and gastrula stages of Xenopus laevis. The particles from both stages induce in gastrula ectoderm the formation of large foreheads (neural-archencephalic-inducing activity), whereas ribosomal subunits have no inducing activity. The inducing activity of particles from both stages is largely abolished after treatment with proteolytic enzymes and to some extent with ribonuclease. The protein moiety of gastrula ribonucleoprotein particles was extracted with phenol and the protein reduced with 2-mercaptoethanol. The protein induces foreheads, but at a lower rate than the intact particles. The protein was fractionated by high-performance liquid size-exclusion chromatography on a derivatized silica gel with 75% formic acid as eluent. The fraction which includes proteins from 10 000 to 16 000 Da has the highest neural-archencephalic-inducing activity.