Changes in d-amphetamine elicited rotational behavior in rats exposed to uncontrollable footshock stress

Male and female rats, selected on the basis of their rotational behavior in response to d-amphetamine, were exposed to either escapable footshock stress, inescapable footshock stress or no stress and were then given a shuttlebox escape task on the subsequent day. Following testing, the magnitude and direction of the animals' rotational responses to d-amphetamine were determined again. Inescapable footshock stress induced a selective change in the direction and intensity of rotational behavior that was dependent upon the subjects' sex and preexisting rotational bias. Right-rotating males and left-rotating females shifted their directional bias toward the opposite side, while left-rotating males and right-rotating females displayed increased rotation in their pre-stress direction. Significant correlations were also noted between the intensity of pre-stress rotational behavior and performance on the shuttlebox shock escape task. The results are discussed with respect to stress' actions on the mesocortical dopamine system and how this system's sex-dependent asymmetrical organization may subserve part of the organism's general reaction to uncontrollable stress.     

Performance of dust respirators with facial seal leaks: I. Experimental

The ability of representative half-mask and single-use respirators with facial seal leaks to provide protection against aerosols was evaluated by experimental measurement. Respirators were mounted on a manikin in a test chamber and operated at seven steady flow rates over the range of 2 to 150 L/min. Samples of polydisperse and monodisperse aerosols were taken from inside and outside the respirator and analyzed by a calibrated optical particle counter over the particle-size range 0.1 to 11.3 microns. Measurements were made separately for filter performance as a function of particle size and flow rate, and simulated leak performance (penetration) as a function of particle size, pressure drop, and leak size. Flow rate vs. pressure drop measurements were made for all filters and leaks tested. For a given leak condition the percentage of the total flow traversing the leak varied several fold over the usual range of airflow rates through a respirator. Aerosol penetration was found to depend strongly on particle size and flow rate for filters, and to depend strongly on particle size and less strongly on pressure drop for leaks. One can conclude from these measurements that the aerosol-size distribution inside a respirator will nearly always be significantly different from that outside the respirator.     

Identification of a point mutation in the topoisomerase II gene from a human leukemia cell line containing an amsacrine-resistant form of topoisomerase II.

HL-60/AMSA is a human leukemia cell line that is 50- to 100-fold more resistant to the cytotoxic actions of the topoisomerase II-reactive intercalator amsacrine than is its drug-sensitive HL-60 parent line. Previously, we have shown that the topoisomerase II from HL-60/AMSA is also resistant to inhibition by amsacrine and other intercalating agents. We therefore sought the molecular basis for the resistance of the topoisomerase II of HL-60/AMSA and, by inference, of the HL-60/AMSA line itself. We report the cloning and sequencing of the topoisomerase II genes from both the sensitive and resistant leukemia cell lines using polymerase chain reaction technology. We have identified a single base change associated with the drug-resistant form of topoisomerase II. This mutation is present in both cloned HL-60/AMSA complementary DNA and extracted HL-60/AMSA genomic DNA. A rapid assay for this mutation in clinical samples has been developed and applied to the DNA of cells from both normal volunteers and leukemia patients. Thus far, the HL-60/AMSA genotype has not been identified in the cells from any individual, suggesting that this genotype is indeed a mutation and not an allelic form of topoisomerase II. The novel assay developed will allow a rapid search for the prevalence of this mutation in clinical samples from patients with leukemia who have relapsed following intercalator therapy.     

Effect of aerosol size on the blood lead distribution of industrial workers

The size distribution measurements of lead aerosol from a brass foundry and primary lead smelter are used to simulate blood lead distributions applying a pharmacokinetic model developed by Bernard. The predicted distribution of blood lead levels determined using the actual size distribution of lead aerosol are compared to the blood lead levels predicted according to the model assumptions adopted in setting the OSHA lead standard. In the furnace area of the smelter and the pouring area of the foundry the predicted mean blood lead level is higher than that found in the standard whereas, in the smelter's sintering and mixing operation the blood lead level is less than that suggested by the standard. The data support the conclusion that size-selective sampling needs to be considered for incorporation into the OSHA lead standard.     

Plasma progesterone concentrations during pregnancy in the dasyurid marsupial, Antechinus stuartii: relationship with differentiation of the embryo

Antechinus stuartii females were sacrificed at various stages of pregnancy timed from the first day that epithelial cell numbers declined in the urine (day 0). Embryos were recovered and their developmental stage assessed, corpora lutea (CL) were fixed for histological sections and the plasma was taken for progesterone determination. The rate of development of the embryo appeared to parallel the formation of the CL and the plasma progesterone concentrations: cleavage (less than day 6) and the expansion of the unilaminar blastocyst (less than day 14), were periods of slow development, during which the formation of the CL was incomplete and plasma progesterone was low [less than 6 ng mL-1 (19.1 nmol L-1)] though steadily increasing. After day 14 the CL reached its maximum size and plasma progesterone was maximally elevated [greater than or equal to 15 ng mL-1 (47.7 nmol L-1)] until parturition on day 27. Rapid differentiation and growth of the embryo occurred between day 22 and day 27.     

Natural history of dermatitis herpetiformis in southern Sweden

A retrospective clinical survey of 96 patients with dermatitis herpetiformis (DH) was performed in two defined populations of 425,000 in southern Sweden. The incidence of DH was 1.05-1.13/100,000 inhabitants/year and the prevalence was approximately 20-25/100,000 inhabitants. In one-third of DH patients the age at onset was greater than 60 years. In women with DH a strong connection to thyroid dysfunction was observed, but also other conditions of probable autoimmune pathogenesis were found in both sexes. No connection to malignant disease was observed. DH seems to be less active the later in life it starts. Several patients with DH manage without dapsone or need dapsone just occasionally in connection with bouts. This is the case even without a gluten-free diet. Many mild cases of DH were observed without a gluten-free diet; therefore, this restricting regimen should be prescribed only in more active cases of DH.     

Modifications in deaf children's vowel production: perceptual evidence

This study examined the perceived changes in vowel articulation by profoundly deaf children as a function of the method of teaching: with visual feedback provided by the Computer Vowel Trainer (CVT) vs conventional methods. The assessment carried out by experienced listeners consisted in marking the sounds heard on the vowel quadrilateral. It was found that changes in perception were feedback and age dependent: younger children taught with the CVT were perceived as displaying more mobility in articulation and they approximated more closely the target vowels than their control counterparts or older children. Progress was evident in particular for back and central vowels. Analysis of perceived discrepancies between target and judged vowels, too, suggested that visual feedback was beneficial: perception of experimental children's utterances showed a marked reduction in substitutions with central vowels, a characteristic pattern of deaf speech. Comparison of these findings with the results yielded by the judgement of the same items by naive listeners indicated broad agreement between the two categories of assessors. Results were discussed in terms of the perceptual and articulatory intervening variables with reference to the specific advantages and constraints imposed by evaluating vowel quality on the vowel plane.