Micronuclei as a marker for medical screening of subjects continuously occupationally exposed to low doses of ionizing radiation

Context: Genotoxicity assays are widely employed in human biomonitoring studies to assess genetic damage inflicted by genotoxic agents.

Objective: Evaluation of micronuclei (MN) as a screening marker of occupational ionizing radiation (IR) exposure.

Materials and methods: Using micronucleus test, peripheral blood lymphocytes (PBL) of 402 control and exposed subjects were screened for genetic damage.

Results: The mean frequencies of micronucleus test parameters were significantly higher in exposed persons. Increase of micronucleus yield with duration of exposure (DOE) by 0.303MN/year was revealed.

Discussion and conclusion: The obtained data encourage us to consider MN as valuable markers for preventive medical screening of occupationally exposed groups.     

The role of hormones in regulating the germination of polymorphic seeds and early seedling growth of Atriplex triangularis under saline conditions

Germination of the polymorphic seeds and seedling growth of Atriplex triangularis under various salinity, gibberellic acid and kinetin treatments were determined. Gibberellic acid (GA₃; 2.9 m M ) promoted germination and growth at high NaCl concentrations (345 m M ). Kinetin (4.7 μ M ) stimulated germination at all salinities and seed sizes tested. GA₃ and kinetin generally increased seedling growth at all concentrations of salinity studied. Higher concentrations of kinetin were found to be inhibitory.     

Incisor microwear of Sumatran anthropoid primates

Several studies have suggested that incisor microwear reflects diet and feeding adaptations of anthropoids. However, such studies have been largely qualitative, and interpretations have relied on anecdotal references to diet and tooth use reported in the socioecology literature. The current study relates incisor microwear in four anthropoid primates to specific ingestive behaviors and food types. Central incisor casts of wild-shot museum specimens of Hylobates lar, Macaca fascicularis, Pongo pygmaeus, and Presbytis thomasi were examined by scanning electron microscopy, and analyzed using a semiautomated image analysis procedure. Microwear patterns were used to generate predictions regarding diet and anterior tooth use. These predictions were evaluated using data collected during a 1 year study of feeding behavior of these same taxa in the wild (Ungar, 1992, 1994a, b). Results suggest that (1) enamel prism relief is associated with the effectiveness of etching reagents in foods, (2) dental calculus buildup results from a lack of incisor use and perhaps the ingestion of sugar-rich foods, (3) striation density varies with degree of anterior tooth use in the ingestion of abrasive food items, (4) striation breadth is proposed to relate to the ratio of exogenous grit to phytoliths consumed; and (5) preferred striation orientation indicates the direction that food items are pulled across the incisors during ingestion. It is concluded that incisor microwear studies can contribute to the understanding of diets and feeding behaviors of extinct primates. © 1994 Wiley-Liss, Inc.     

Human monocytes in culture synthesize and secrete lipoprotein lipase

Within the first day in culture, human monocytes begin to synthesize and secrete a triglyceride lipase. The designation of this activity as lipoprotein lipase is based upon: 1) a requirement of serum or apolipoprotein C-II for full activity; 2) inhibition by 1M NaCl or apolipoprotein C-III₂; 3) a pH optimum of 8; and 4) binding to endothelial cells that is releasable by heparin. The enzyme also exhibits immunological cross reactivity with antibody to purified bovine milk lipoprotein lipase as does human postheparin plasma lipoprotein lipase. Lymphocytes and polymorphonuclear leukocytes do not appear to contain this enzyme.     

Last‐century changes of alpine grassland water‐use efficiency: a reconstruction through carbon isotope analysis of a time‐series of Capra ibex horns

The ecophysiological response of an alpine grassland to recent climate change and increasing atmospheric CO₂ concentration was investigated with a new strategy to go back in time: using a time‐series of Capra ibex horns as archives of the alpine grasslands' carbon isotope discrimination (¹³Δ). From the collection of the Natural History Museum of Bern, horns of 24 males from the population of the Augstmatthorn–Brienzer Rothorn mountains, Switzerland, were sampled covering the period from 1938 to 2006. Samples were taken from the beginning of each year‐ring of the horns, representing the beginning of the horn growth period, the spring. The horns' carbon ¹³C content (Δ¹³C) declined together with that of atmospheric CO₂ over the 69‐year period, but ¹³Δ increased slightly (+0.4‰), though significantly (P<0.05), over the observation period. Estimated intercellular CO₂ concentration increased (+56 μmol mol^?1) less than the atmospheric CO₂ concentration (+81 μmol mol^?1), so that intrinsic water‐use efficiency increased by 17.8% during the 69‐year period. However, the atmospheric evaporative demand at the site increased by approximately 0.1 kPa between 1955 and 2006, thus counteracting the improvement of intrinsic water‐use efficiency. As a result, instantaneous water‐use efficiency did not change. The observed changes in intrinsic water‐use efficiency were in the same range as those of trees (as reported by others), indicating that leaf‐level control of water‐use efficiency of grassland and forests followed the same principles. This is the first reconstruction of the water‐use efficiency response of a natural grassland ecosystem to last century CO₂ and climatic changes. The results indicate that the alpine grassland community has responded to climate change by improving the physiological control of carbon gain to water loss, following the increases in atmospheric CO₂ and evaporative demand. But, effective leaf‐level water‐use efficiency has remained unchanged.     

Premolar microwear and tooth use in Australopithecus afarensis

The mandibular third premolar (P₃) of Australopithecus afarensis is notable for extensive morphological variability (e.g., metaconid presence/absence, closure of the anterior fovea, root number) and temporal trends in crown length and shape change over its 700 Ka time range. Hominins preceding A. afarensis have unicuspid, mesiodistally elongated P₃s with smaller talonids, and subsequent australopiths have bicuspid, more symmetrically-shaped P₃ crowns with expanded talonids. For these features, A. afarensis is intermediate and, thus, evinces the incipient stages of P₃ molarization. Here, we examine A. afarensis P₃ Phase II microwear and compare it with that of Australopithecus africanus and Cercocebus atys, an extant hard-object specialist, to assess whether the role of the P₃ in food processing changed over time in A. afarensis. Premolar Phase II microwear textures are also compared with those of the molars to look for evidence of functional differentiation along the tooth row (i.e., that foods with different mechanical properties were processed by separate regions of the postcanine battery). Microwear textures were also examined along the mesial protoconid crest, the site of occlusion with the maxillary canine, of the A. afarensis P₃ and compared with the same region in Pan troglodytes to determine whether microwear can be useful for identifying changes in the occlusal relationship between the P₃ and maxillary canine in early Australopithecus. Finally, temporal trends in P₃ Phase II and mesial microwear are considered. Results indicate that 1) both the P₃ and molar Phase II facets of A. afarensis have less complex microwear textures than in A. africanus or C. atys; 2) A. afarensis P₃ and molar Phase II textures differ, though not to the extent seen in taxa that eat hard and tough items; 3) microwear along the A. afarensis mesial protoconid crest is clearly distinct from that of the P. troglodytes, indicating that there is no honing equivalent in A. afarensis; and 4) there is little evidence of change over time in A. afarensis P₃ microwear on either the mesial or Phase II facet. In sum, these results provide no evidence that A. afarensis routinely loaded either its premolars or molars to process hard objects or that A. afarensis P₃ function changed over time.     

INFLUENCE OF HORMONAL TREATMENTS ON THE GROWTH OF TWO HALOPHYTIC SPECIES OF SUAEDA

Experiments were made to determine the interaction between the growth regulating substances, gibberellic acid and kinetin, and salinity on the growth and development of two species of Suaeda. We found that the growth of Suaeda maritima var. macrocarpa, an obligate halophyte, was greatly stimulated with treatments by both of these hormones in controls not treated with sodium chloride. These results suggest that halophytes grow poorly under nonsaline conditions because of some type of hormonal imbalance. GA₃ was found to stimulate growth at all salinities for both S. maritima var. macrocarpa and S. depressa, while kinetin proved to be inhibitory to growth and elongation of plants at higher salinities. Chlorophyll content decreased with salt treatments and was not significantly influenced by hormonal treatments. GA₃ had little influence on water content in roots and shoots, whereas plants treated with kinetin generally had reduced water contents.     

In vitro screening of therapeutic agents against Cryptosporidium: hyperimmune cow colostrum is highly inhibitory.

An in vitro model of Cryptosporidium parvum infection was developed utilizing an adherent human intestinal epithelial cell line HT29.74. The efficacy of potential immunologic therapy in the form of Cryptosporidium-specific hyperimmune bovine colostrum was evaluated for the ability to inhibit in vitro infection. Oocysts were purified from stool of chronically infected AIDS patients. Hyperimmune colostrum obtained from cows immunized with Cryptosporidium and nonimmune conventional colostrum were evaluated. oocysts (10(5)-10(6)) were pre-incubated with either hyperimmune colostrum, conventional colostrum, or saline as control, for 15 min at room temperature than applied to a 70% confluent monolayer of HT29.74 cells. Cryptosporidium schizonts were identified and counted per 1,000 HT29.74 cells under oil immersion after 24 h. In the presence of hyperimmune colostrum, parasite infection was inhibited by 82% (p less than 0.001), and the presence of conventional colostrum, infection was inhibited by 67% (p less than 0.001). Treatment with the soluble fraction of hyperimmune colostrum resulted in 69% inhibition (p less than 0.001) compared to the soluble fraction of conventional colostrum which resulted in only 17% inhibition (p = NS). In vitro Cryptosporidium parvum infection of the differentiated human enterocyte cell line HT29.74 is a viable method for screening immunologic therapies. Hyperimmune bovine colostrum was highly inhibitory of Cryptosporidium infection in vitro and its soluble fraction remained significantly inhibitory while the soluble fraction of conventional colostrum did not.