The effects of acute and chronic hypoxia on cortisol, glucose and lactate concentrations in different populations of three-spined stickleback.

The response of individuals from three different populations of three-spined sticklebacks to acute and chronic periods of hypoxia (4.4 kPa DO, 2.2 mg l⁻¹) was tested using measures of whole-body cortisol, glucose and lactate. Although there was no evidence of a neuroendocrine stress response to acute hypoxia, fish from the population least likely to experience hypoxia in their native habitat had the largest response to low oxygen, with significant evidence of anaerobic glycolysis after 2 h of hypoxia. However, there was no measurable effect of a more prolonged period (7 days) of hypoxia on any of the fish in this study, suggesting that they acclimated to this low level of oxygen over time. Between-population differences in the analytes tested were observed in the control fish of the acute hypoxia trial, which had been in the laboratory for 16 days. These differences were not apparent among the control fish in the chronic exposure groups that had been held in the laboratory for 23 days, suggesting that these site-specific trends in physiological status were acclimatory. Overall, the results of this study suggest that local environmental conditions may shape sticklebacks' general physiological profile as well as influencing their response to hypoxia.

Formation of nanostructured, nanocrystalline boron nitride microparticles with diatom-derived 3-D shapes.

The first use of diatom frustules as shape-dictating 3-D templates for the syntheses of nanostructured, nanocrystalline micro-particles of a non-oxide ceramic, boron nitride, is demonstrated.

Transition-metal-promoted reactions of boron hydrides. 17. Titanium-catalyzed decaborane-olefin hydroborations.

The titanium-catalyzed hydroboration reactions of decaborane with a variety of terminal olefins have been found to result in the exclusive, high-yield formation of monosubstituted decaborane 6-R-B(10)H(13) products, arising from anti-Markovnikov addition of the cage B6-H to the olefin. The titanium-catalyzed reactions are slow, often less than one turnover per hour; however, their high selectivities and yields coupled with the fact that they are simple, one-pot reactions give them significant advantages over the previously reported routes to 6-R-B(10)H(13) compounds. The catalyst also has extended activity with reactions carried out for as long as 13 days, showing little decrease in reactivity, thereby allowing for the production of large amounts of 6-R-B(10)H(13). The titanium-catalyzed reactions of decaborane with the nonconjugated diolefins, 1,5-hexadiene and diallylsilane, were found to give, depending upon reaction conditions and stoichiometries, high yields of either alkenyl-substituted 6-(CH(2)=CH(CH(2))(4))-B(10)H(13) (4) and 6-(CH(2)=CHCH(2)SiMe(2)(CH(2))(3))-B(10)H(13) (5) or linked-cage 6,6'-(CH(2))(6)-(B(10)H(13))(2) (6) and Me(2)Si(6-(CH(2))(3)-B(10)H(13))(2) (7) compounds, respectively. The unique tetra-cage product, Si(6-(CH(2))(3)-B(10)H(13))(4) (8), was obtained by the catalyzed reaction of 4 equiv of decaborane with tetraallylsilane. Sequential use of the titanium catalyst and previously reported platinum catalysts (PtBr(2) or H(2)PtCl(6).6H(2)O with an initiator) provides an efficient pathway to asymmetrically substituted 6-R-9-R'-B(10)H(12) species. The structures of compounds 5, 6, and 8, as well as a platinum derivative, (PSH(+))(2)-commo-Pt-[nido-7-Pt-8-(n-C(8)H(17))B(10)H(11)](2)(2-), of 6-(n-octyl)decaborane have been established by single-crystal crystallographic determinations.

Syntheses and structural and electrochemical characterizations of vanadatricarbadecaboranyl analogues of vanadocene and the structural characterization of the [Li(CH(3)CN)2+](6-CH(3)-nido-5,6,9-C(3)B(7)H(9-) tricarbadecaboranyl anion.

A single-crystal X-ray determination of the [Li(CH(3)CN)(2)(+)](6-CH(3)-nido-5,6,9-C(3)B(7)H(9)(-)) salt has shown that the 6-CH(3)-nido-5,6,9-C(3)B(7)H(9)(-) tricarbadecaboranyl anion has a nido-cage geometry based on an octadecahedron missing the unique six-coordinate vertex. The resulting six-membered open face is puckered, with two of the cage carbons (C6 and C9) occupying the low-coordinate cage positions above the plane of the four remaining atoms (C5, B7, B8, and B10). The Li(+) ion is centered over the open face and is solvated by two acetonitrile molecules. The reactions of the 6-CH(3)-nido-5,6,9-C(3)B(7)H(9)(-) anion with various vanadium halide salts, including VCl(4), VCl(3), and VBr(2), each resulted in the isolation of the same five paramagnetic products (2-6) of composition V(CH(3)-C(3)B(7)H(9))(2). X-ray crystallographic determinations of 2-5 showed that the complexes consist of two octadecahedral VC(3)B(7) fragments sharing a common vanadium vertex and established their structures as commo-V-(1-V-4'-CH(3)-2',3',4'-C(3)B(7)H(9))(1-V-2-CH(3)-2,3,4-C(3)B(7)H(9)) (2), commo-V-(1-V-5'-CH(3)-2',3',5'-C(3)B(7)H(9))(1-V-4-CH(3)-2,3,4-C(3)B(7)H(9)) (3), commo-V-(1-V-5'-CH(3)-2',3',5'-C(3)B(7)H(9))(1-V-2-CH(3)-2,3,4-C(3)B(7)H(9)) (4), and commo-V-(1-V-2-CH(3)-2,3,4-C(3)B(7)H(9))(2) (5). These complexes can be considered as tricarbadecaboranyl analogues of vanadocene, (eta(5)-C(5)H(5))(2)V. However, unlike vanadocene, these complexes are air- and moisture-stable and have only one unpaired electron. The five complexes differ with respect to one another in that they either (1) contain different enantiomeric forms of the CH(3)-C(3)B(7)H(9) cages, (2) have a different twist orientation of the two cages, or (3) have the methyl group of the CH(3)-C(3)B(7)H(9) cage located in either the 2 or 4 position of the cage. Subsequent attempts to oxidize the compounds with reagents such as Br(2) and Ag(+) were unsuccessful, illustrating the ability of the tricarbadecaboranyl anion to stabilize metals in low oxidation states. Consistent with this, both the electrochemical oxidation and the reduction of 2 were much more positive than those of the same oxidation state changes in vanadocene. The one-electron reduction of 2 is a remarkable 2.9 V positive of that of Cp(2)V.

Facial paralysis in Wegener's granulomatosis of the middle ear.

A case of Wegener's granulomatosis, which presented as chronic otitis media with facial nerve palsy, is described. Early diagnosis is vital if unnecessary surgical exploration is to be avoided. A false negative cANCA may delay the diagnosis, especially in cases of locoregional disease, and a policy of repeated titres should be adopted, if clinical suspicion is high.

Agonistic behaviour and biogenic amines in shore crabs Carcinus maenas.

To investigate the role of certain neurohormones in agonistic behaviour, fights were staged between pairs of size-matched male shore crabs Carcinus maenas, and blood samples were taken immediately after the contests had been resolved. Samples were also taken from these crabs at rest (before and after fighting) and after walking on a treadmill. A control group of crabs also had samples taken on each experimental day. Concentrations of tyramine, dopamine, octopamine, serotonin (5-HT) and norepinephrine were determined in each blood sample using a gas chromatography/mass spectrometry (GC-MS) system. Norepinephrine was not detectable in any of the samples, but the standards were recovered. Tyramine values were not significantly different between the control group and the fought group, so tyramine does not appear to be important in agonistic behaviour. A comparison between the control and fought groups shows that fighting had an effect on the concentrations of octopamine, dopamine and 5-HT, but exercise only had an effect on octopamine levels, which showed a reduction from resting values in both winners and losers. Resting and post-fight concentrations of octopamine, dopamine and 5-HT were higher in winners than in losers. 5-HT concentration increased in the blood of fought crabs from resting values, whereas dopamine concentration decreased. In winners, octopamine concentrations decreased from resting values, but in losers octopamine levels increased from resting concentrations. The escalatory behaviour or intensity of fighting performed by winners and losers was related to dopamine levels but not to those of octopamine or 5-HT. Therefore, there appears to be a link between relative concentrations of these three amines (dopamine, octopamine and 5-HT) and fighting ability; the effects are not simply a result of activity. The better competitors have higher concentrations of these three amines at rest and after fighting.

Cytotoxicity of ferratricarbadecaboranyl complexes in murine and human tissue cultured cell lines.

The ferratricarbadecaboranyl salts [1-(eta 5-C5H5)Fe-2-CH3-2,3,4-C3B7H9] + X-(X- = AsF6-, 1 and SbF6-, 2), as well as the neutral complex, 1-(eta 5-C5H5)Fe-2-CH3-2,3,4-C3B7H9, 4, are effective cytotoxic agents, causing cell death in a number of tissue culture lines, e.g. L-1210, Tmolt3, HL-60, and HeLa-S3. In general, these agents were not active against the solid cell growth, i.e. KB nasopharynx, A431 skin, HCT-8 ileum, SW480 colon, osteosarcoma, and glioma. However, they were active against the growth of lung bronchogenic MB-9812. The mode of action of the derivatives involves inhibition of de novo purine synthesis of L-1210 cells, which reduces DNA and RNA syntheses. Purine synthesis was reduced by complexes [1-(eta 5-C5H5)Fe-2-CH3-2,3,4-C3B7H9]+ [SbF6]- 2 and ¿[1-(eta 5-C5H5)Fe-2-CH3-2,3,4-C3B7H9]+ [SbF6]- [1-(eta 5-C5H5)Fe-4-CH3-2,3,4-C3B7H9]+ [SbF6]-¿ [20:1] 3, at the regulatory enzyme, i.e. PRPP amido transferase. The agents lowered d[ATP] and d[CTP] pools, further reducing DNA synthesis. The salts 1, 2, and 3 were shown to be moderate inhibitors of isolated L-1210 DNA topoisomerase activity. DNA strand scission was evident after incubation with compounds 1-4 and [1-(eta 5-C5H5)Fe-2-CH3-2,3,4-C3B7H9 and 1-(eta 5-C5H5)Fe-4-CH3-2,3,4-C3B7H9] [20:1] 5, for 24 hours at 100 microM, lowering DNA synthesis, and causing cell death. The ferratricarbadecaboranes show activities and specificities different than those found for the analogous ferrocenium salts [(eta 5-C5H5)2Fe]+ [AsF6]- 6 and [(eta 5-C5H5)2Fe]+ [SbF6]- 7, and the neutral ferrocene compound (eta 5-C5H5)2Fe 8. The bioactivites of both the tricarbaboranyl and metallocenium salts are attributed to the cations, since Na+[AsF6]- 9, K+ [AsF6]- 10, Na+[SbF6]- 11, and K+[SbF6]- 12 were found to be inactive at equivalent ionic concentration.