An ultrastructural comparison of carcinogen-associated and spontaneous aortic lesions in the cockerel

Ultrastructural studies were performed on arteriosclerotic aortic lesions in cockerels given weekly injections (10 mg/kg, 4-36 weeks of age) of the carcinogen 7,12-dimethylbenz(a)anthracene (DMBA) and on spontaneous lesions in age-matched controls. Lesions were observed in all animals. Regardless of treatment, lesions of similar size were indistinguishable. They were composed primarily of modified smooth muscle cells, (SMC) which were oriented more randomly than medial SMCs. The interstitia were composed mainly of collagen. Lesion cells displayed invaginated nuclei and dense bodies characteristic of normal SMCs but were modified in shape and displayed fewer myofilaments and more rough endoplasmic reticulum than did normal SMCs. Larger lesions, found only in DMBA-treated animals, contained relatively few cells and more collagen. These cells, which contained dense bodies but not myofilaments, were flatter and more uniformly oriented than cells in smaller lesions. Thus, there is a size continuum of arteriosclerotic lesions in the cockerel. Chronic DMBA treatment accelerates size increases of spontaneous lesions rather than inducing the formation of new lesions. In this system, DMBA appears to "promote" rather than "initiate" the lesions.

Microwave bioeffects in the erythrocyte are temperature and pO2 dependent: cation permeability and protein shedding occur at the membrane phase transition

Microwave exposure (2450 MHz, 60 mW/g, CW) of rabbit erythrocytes increases Na passive transport only at membrane phase transition temperatures (Tc) of 17-19 degrees C. This permeability effect is enhanced for relative hypoxia which is characteristic of intracellular oxygen tension (pO2 less than or equal to 5 mm Hg). Neither the permeability nor the pO2 effects are observed in temperature-matched (+/- 0.05 degrees C), sham-exposed controls. In addition, at Tc, microwave exposure is observed to induce the shedding or release of two erythrocyte proteins not seen in sham-exposed controls. Moreover, the enhanced shedding of at least seven other proteins all of molecular weight less than or equal to 28,000 D was detected in the microwave-treated samples. Using sensitive silver staining we estimate that approximately 450 fg of protein were shed per erythrocyte. These results demonstrate that temperature and pO2 are important influences on both functional and structural responses of cell membranes to microwave radiation.

Cigarette smoke and carbon monoxide do not have equivalent effects upon development of arteriosclerotic lesions

Experiments were performed to test whether exposure to mainstream cigarette smoke, without any diet modification, was sufficient to exacerbate arteriosclerotic lesion development in cockerels. Additionally, the experiments were designed to test whether any such effect could be attributed solely to carbon monoxide (CO) in the smoke. Three groups of cockerels (7/group) were exposed 5 days/week in standard inhalation chambers. Each day, one group (smoke) was exposed to smoke produced from the combustion of two packs of cigarettes. A second group (CO) was exposed to CO at levels equivalent to those produced during the combustion of two packs of cigarettes. A third group was sham-exposed. Following sacrifice, the abdominal aorta of each animal was cut into 5 mm segments and the extent of arteriosclerotic lesion development was measured. In smoke animals, compared to those in either of the other two groups, there were more aortic segments with measurable lesions present and the cross-sectional areas of these segments were greater. On a comparative basis, the smoke lesions were three times larger than in either of the other two groups, despite the fact that blood carboxyhemoglobin levels were the same in CO and smoke animals. The location of the lesions and their histological appearance were very similar to those previously described for spontaneous and carcinogen-associated lesions in the cockerel. These results demonstrate that as little as four months of daily exposure to cigarette smoke, in the absence of a cholesterol supplemented diet, can help accelerate arteriosclerotic lesion development. Further, this accelerated development cannot be attributed solely to CO in the smoke.

Dose-dependent size increases of aortic lesions following chronic exposure to 7,12-dimethylbenz(a)anthracene

The prevalence, size, and patterns of distribution of arterial lesions (plaques) were investigated in cockerels exposed chronically to 7,12-dimethylbenz(a)anthracene (DMBA). Animals, from 5 to 20 weeks of age, received weekly i.m. injections of 5, 10, or 20 mg of DMBA per kg, dissolved in dimethyl sulfoxide. Control animals received weekly injections of dimethyl sulfoxide. All animals were sacrificed at 21 weeks of age. The entire aorta from each animal was cut transversely into 5-mm segments starting at the iliac trifurcation. The cross-sectional area of plaques was determined by light microscopic analysis of sections taken from the face of each segment. Plaque frequency was similar in DMBA-treated and control groups. However, mean plaque cross-sectional area was 7- to 11-fold higher for the treatment groups than for the controls. The distribution of plaque areas in both treated animals and controls was consistent with a log normal distribution. Median cross-sectional area and plaque volume index each increased in a linear fashion with DMBA dose. Small plaques were present in all groups. Large plaques were present only in DMBA-treated animals. Labeling indices of plaques, although low, were 2.3- to 26-fold higher than for underlying medial smooth muscle cells. The data indicate that the primary response to chronic DMBA exposure is a dose-dependent size increase of spontaneous aortic lesions and not the induction of new lesions.

Presumably Azorean disease in a presumably non-Portuguese family

Autosomal dominant motor system degeneration (ADMSD) is a hereditary ataxia that has been reported previously only in Portuguese families from the Azores Islands. Cerebellar ataxia, pyramidal and extrapyramidal signs, amyotrophy, dystonia, abnormal eye movements, and prominent eyes are variably present. Four members of a family had cerebellar ataxia, dystonic posturing, a variety of abnormal eye movements, and prominent eyes resulting from lid retraction. Eight other family members had a similar disease. The combination of cerebellar ataxia, dystonia, abnormal eye movements, and prominent eyes has been reported only in ADMSD. The family reported here may be the first example of ADMSD in a non-Portuguese family.

Modification of the gelatin substrate procedure for demonstration of acrosomal proteolytic activity

In situ proteolytic activity in the heads of sperm of seven mammalian species has been demonstrated using autoradiographic film as a gelatin substrate. The film is first exposed and processed and then coated with the sperm sample. Proteolytic activity is monitored by following the appearance of "halos," which are areas of gelatin digestion and are found to surround the heads of reacting sperm. The proteolytic factor appears to be released from the acrosome and may be the protease with trypsin-like activity that has been found associated with the acrosome in biochemical studies. l-Chloro-3-tosylamido-7-amino-2-heptanone and diisopropyl fluorophosphate, both of which inhibit trypsin activity, apparently interact with a substance released from the acrosome but do not interfere with the formation of halos. Sperm treated with trichloroacetic acid, urea or formalin do not form halos.