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  • Author: J. W. Ross x
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Abstract

The red algal genus Mazzaella presents an interesting challenge to systematists and ecologists. The two species M. linearis and M. splendens are easily distinguished in their ideal form; however, in areas of intermediate wave exposure individuals form a seemingly continuous grade between the two species. On the basis of ecological investigations, it was concluded that the two forms are distinct at the species level and that plants of intermediate morphology can be best assigned to M. splendens. Field-identified ‘classic’ M. linearis and M. splendens (17 individuals each), as well as individuals of intermediate morphology (20 individuals), were collected. Sequences of the internal transcribed spacer (ITS) of the ribosomal cistron were determined for all of these individuals, as well as for related Mazzaella spp. Molecular phylogenetic analyses confirmed a close relationship between M. linearis and M. splendens, and identified their closest relative, M. sanguinea. Pairwise distance comparisons within M. splendens (including intermediate plants; 0–4 differences) and M. linearis (0–2 differences) were less than variation between species (8–12 differences), and both solidly clustered as monophyletic (M. sanguinea as outgroup; 0–2 differences among four isolates) confirming the results of the ecological investigations. Two further aspects of the earlier ecological studies are also discussed: the conclusion that stipe length is a reliable character for distinguishing between these two species; and, a suggestion that M. splendens displays a slightly heteromorphic alternation of generations, the plants of intermediate morphology being tetrasporophytes (preferring the moderately wave-exposed habitats) whereas the ‘classic’ M. splendens are gametophytic with a preference for wave-sheltered habitats.

Summary

A new (radio)iodinated AMPA receptor ligand has been developed and pharmacologically evaluated in vitro and ex vivo using rodents. The new radioligand was directly labeled by electrophilic radioiodo-destannylation with iodine- 131 in high radiochemical yields of 97% within 2 min. The new radioligand showed an excellent initial brain uptake of 2.1%ID/g at 10 min post injection, but a fast wash-out reduced the uptake by about 10-fold at 60 min post injection. Due to high nonspecific binding accompanied with a uniform distribution in brain tissue, however, the new radiotracer appears not suitable for AMPA receptor imaging in vivo.

Abstract

Phase egg, first described by Eggleton et al. (1978), was synthesized and its composition determined to be AlSiO3OH. The crystal structure of AlSiO3OH, including the position of the hydrogen, has been solved and refined from high-resolution X-ray powder diffraction. The resulting lattice constants are a = 7.14409(2) Å, b = 4.33462(1) Å, c = 6.95253(2) Å, and β = 98.396(1)°. The space group is P21\n; Z = 4, V0 = 212.99(1) Å3, and the zero pressure density is 3.74 g/cm3. This phase, which has features in common with the sti-shovite structure, occurs above 11 GPa and 700 ℃. AlSiO3OH forms from topaz-OH with increasing pressure and persists to more than 17.7 GPa and 1300 ℃. From a Schreinemaker analysis, we predicted that phase egg decomposes with pressure to an unknown, possibly hydrous aluminosilicate. Potentially, phase egg could replace topaz-OH or kyanite in sub­ducted crustal bulk compositions and may transport some water into the deep Earth.

Abstract

OBJECTIVES: Our objectives were two-fold: 1) to determine the frequency of discordant umbilical artery Doppler systolic to diastolic (S/D) ratios in the individual umbilical arteries of growth-restricted fetuses and 2) to examine the impact of the frequency of discordance on clinical outcomes. METHODS: This was a prospective, observational study of growth-restricted fetuses. Doppler velocimetry was performed weekly and two S/D ratios were obtained for each fetal umbilical artery. Inter-artery discordance was defined as a difference in measurement categories (i.e., normal, elevated, absent, reversed) between the arteries. The number of abnormal measurements per visit was summed to 0-4 out of 4 values. A composite average number of abnormal Doppler measurements was calculated and fetuses were stratified based on degree of average number of abnormalities in increments of 25%: 0-<25%, 25-<50%, 50-<75%, and 75-100% abnormality. RESULTS: Of a total 241 fetuses (1762 visits), 110 (45.6%) had abnormal UAD flow and 189 (66%) demonstrated discordance. Abnormal values were noted in only one artery in 53% (n=151) of visits. Fetuses with any abnormal Doppler testing had smaller birthweights compared to fetuses with consistently normal testing (2485g vs 2623g, p <0.01); birthweight decreased as composite average of abnormal measurements increased (p = 0.03). CONCLUSION: The majority (66%) of fetuses with abnormal testing demonstrated UAD discordance. Up to 53% of fetuses could have been misdiagnosed if only one artery was tested. Fetuses with a higher frequency of Doppler abnormalities had lower birthweights. We propose obtaining two measurements from each umbilical artery in growth-restricted fetuses.

Abstract

Regioselective introduction and transformation of substituents at the C1 carbon of N-tert-butoxycarbonyl-5-syn-tert-butyldimethylsilyloxymethyl-2-azabicyclo[2.1.1]hexane (7) is described. These azabicycles are precursors to conformationally constrained β-amino acids with potential to form oligomers with definite secondary structures. Selected examples of these precursors are converted into their corresponding amino acid derivatives.

Abstract

OBJECTIVES: To evaluate short- and long-term growth in fetuses with growth restriction (FGR) and elevated umbilical artery Doppler (UAD) systolic/diastolic (S/D) ratios.

METHODS: In this prospective observational study, two UAD waveforms were obtained from each umbilical artery weekly and were classified as normal or abnormal. Fetal growth was assessed every 3 weeks. Short-term growth was calculated from the first visit with elevated ratios until next growth assessment. Results were grouped by number of initial elevated S/D ratios (maximum, 4). Long-term growth was evaluated by change in estimated fetal weight from diagnosis of FGR to birth weight. Fetuses were grouped by average number of elevated S/D ratios and compared to a reference population of growth restricted fetuses with normal testing.

RESULTS: Of 241 fetuses evaluated, 105 demonstrated elevated S/D ratios. Short-term growth was impaired when fetuses had elevated S/D ratios. Long-term growth was affected when the average number of elevated S/D ratios was ≥1 per visit. Progressive 3 or 4 growth delay was noted as the average number of abnormal S/D ratios increased.

CONCLUSIONS: Short- and long-term fetal growth are affected by elevated UAD S/D ratios. Fetuses with more abnormal values initially and those with a higher average of elevated values over pregnancy demonstrate decreased growth.

Abstract

Background: Cerebrospinal fluid (CSF) amyloid β1-42 (Aβ1-42), total tau (T-tau) and phosphorylated tau181 (P-tau) are finding increasing utility as biomarkers of Alzheimer’s disease (AD). The purpose of this study was to determine whether measured CSF biomarker concentrations were affected by aliquot storage volume and whether addition of detergent-containing buffer mitigates any observed effects.

Methods: AD and control CSF was distributed into polypropylene tubes in aliquots of different volumes (50–1500 μL). Aβ1-42, T-tau and P-tau were measured with and without addition of Tween 20 (0.05%).

Results: Measured concentrations of Aβ1-42 increased two-fold with aliquot storage volume. A volume increase of 10 µL caused an Aβ1-42 increase of 0.95 pg/mL [95% confidence interval (CI) 0.36–1.50, p=0.02] in controls, and 0.60 pg/mL (CI 0.23–0.98 pg/mL, p=0.003) in AD samples. Following addition of Tween 20, the positive relationship between Aβ1-42 and aliquot volume disappeared. T-tau and P-tau were not significantly affected.

Conclusions: CSF aliquot storage volume has a significant impact on the measured concentration of Aβ1-42. The introduction of a buffer detergent at the initial aliquoting stage may be an effective solution to this problem.