Human nails as a biomarker of arsenic exposure from well water in Inner Mongolia: comparing atomic fluorescence spectrometry and neutron activation analysis.

Arsenic (As) is found naturally in the geological strata within the Ba Men Region of Inner Mongolia, China. A study was conducted to compare the total As measurements from two analytical techniques: instrumental neutron activation analysis (INAA) and atomic fluorescence spectrometry (AFS), and to verify nails as an exposure biomarker in this population. In 1999, nail and water samples were collected in a pilot study. Fingernails and toenails were pooled from 32 participants and analysed for total As by both INAA and AFS. Mean nail As values were 14.8+/-2.4 and 19.4+/-2.8 microg g-1 (+/-SEM) for INAA and AFS, respectively. Results from these two methods were significantly correlated (r=0.93, p<0.0001). In 2000, a second study was conducted and INAA was used to measure total As in toenails from 314 Ba Men residents. Well water samples were collected from 121 households and analysed by AFS. A significant correlation was observed between toenail and well water As (r=0.84, p<0.0001). Based on the results, INAA was significantly correlated with AFS and proved to be a reliable measure of nail As levels. In this population, toenail samples are a useful internal As exposure biomarker from drinking water sources.     

Exposure to a combination of heat and hyperoxia during cycling at submaximal intensity does not alter thermoregulatory responses

In this study, we tested the hypothesis that breathing hyperoxic air (F_inO₂ = 0.40) while exercising in a hot environment exerts negative effects on the total tissue level of haemoglobin concentration (tHb); core (T_core) and skin (T_skin) temperatures; muscle activity; heart rate; blood concentration of lactate; pH; partial pressure of oxygen (P_aO₂) and carbon dioxide; arterial oxygen saturation (S_aO₂); and perceptual responses. Ten well-trained male athletes cycled at submaximal intensity at 21°C or 33°C in randomized order: first for 20 min while breathing normal air (F_inO₂ = 0.21) and then 10 min with F_inO₂ = 0.40 (HOX). At both temperatures, S_aO₂ and P_aO₂, but not tHb, were increased by HOX. Tskin and perception of exertion and thermal discomfort were higher at 33°C than 21°C (p < 0.01), but independent of F_inO₂. T_core and muscle activity were the same under all conditions (p > 0.07). Blood lactate and heart rate were higher at 33°C than 21°C. In conclusion, during 30 min of submaximal cycling at 21°C or 33°C, T_core, T_skin and T_body, tHb, muscle activity and ratings of perceived exertion and thermal discomfort were the same under normoxic and hyperoxic conditions. Accordingly, breathing hyperoxic air (F_inO₂ = 0.40) did not affect thermoregulation under these conditions.     

Ultrastructural localization of the high molecular weight proteins associated with in vitro-assembled brain microtubules

Microtubules isolated from brain extracts by in vitro assembly (1, 19, 23) are composed principally of two tubulins and two high molecular weight proteins (microtubule-associated proteins [MAPS] 1 and 2) (2,5,7,20). Recently, it was demonstrated that in vitro-assembled brain microtubules (neurotubules) are coated with filaments (5, 7) which are similar to the filaments attached to neurotubules in situ (4, 15, 21, 24, 25), and it was suggested that the filaments are composed of the higher molecular weight MAPs (5, 7, 12). In this study, microtubules were assembled in the presence and absence of the MAPs, and thin sections of the microtubules were examined by electron microscopy. The results show that the filaments only occur on microtubules assembled in the presence of the MAPs and it is therefore concluded that the filaments are composed of the high molecular weight MAP's.     

L-chromosome inheritance and the problem of chromosome “imprinting” in Sciara (Sciaridae,Diptera)

The loss of the L-chromosomes from the germ line of a newly-collected strain of Sciara impatiens was used as a genetic marker to test whether the supernumeraries in this genus obey the rule of origin which governs the behavior of the regular homologues at first meiotic anaphase in the male. Reciprocal crosses between a normal strain which possessed L's and the no-L line yielded F₁ males whose germ cells contained L-chromosomes of paternal or of maternal origin. Cytological study of the gonads of these males showed that in all instances, irrespective of their origin, the L-chromosomes were conserved. To demonstrate that the L's thus conserved are not lost subsequently during spermiogenesis, the F₁ males derived from normal fathers were bred to females from the no-L line; the gonads of the test-cross progeny showed that these individuals had inherited L-chromosomes. The failure of the paternal L's to obey the rule of origin during spermatogenesis indicates that the supernumeraries in this genus are not subject to the reversible imprinting which the regular complement undergoes. And the genetic effects of exclusively paternal or maternal L-chromosomes on germ cell development and maturation are indistinguishable. Concomitant with the loss of L's from the germ line, the newly-collected strain of S. impatiens underwent an abrupt alteration from unisexual families to variable sex ratios. These ratios are discussed in relation to the problem of sex determination in S. ocellaris, a species which sustained L-chromosome loss during the course of evolution. Discussed also are some new unpublished data which reveal, unexpectedly, a genetic affinity between ocellaris and impatiens. The no-L line of impatiens, which has been kept in laboratory culture for approximately four years, provides a unique opportunity to examine the conditions under which the supernumeraries are retained or lost and also to determine more precisely the nature of their genetic effects.It is a pleasure to acknowledge support by the National Science FoundationIt is a pleasure to acknowledge support by the National Science Foundation     

The standardization of inactivated equine influenza vaccines by single-radial immunodiffusion

Single-radial-immunodiffusion (SRD) assays were used for measuring the haemagglutinin (HA) antigen content of equine influenza vaccines containing the virus strains A/equine/Prague/56 (H7N7) and A/equine/Miami/63 (H3N8). Three bivalent aqueous vaccines and one bivalent adjuvanted vaccine were standardized by SRD to contain graded amounts of HA antigen activity. The SRD reaction was influenza subtype specific and was not influenced by the presence of adjuvant in vaccine.     

Proteinase activities of the golden hamster eggs and cells of the cumulus oophorus

Proteinase activities of eggs and cells of the cumulus oophorous of the golden hamster were investigated with highly sensitive fluorogenic amide substrates. Eggs contain a neutral endopeptidase which hydrolyzed Suc-Ala-Ala-Phe-7-amino-4-methylcoumarin amide between the Ala and the Phe residues. Endopeptidase action on this substrate resulted in the accumulation of Phe-7-amino-4-methylcoumarin amide which was monitored by tlc identification. Hamster eggs also contained aminopeptidase and elastase-like activities but no detectable trypsin-like activity. Aminopeptidase, endopeptidase, trypsin-like, and elastase-like activities were detected in cumulus cells.