Cleavage of amyloid beta peptide during constitutive processing of its precursor

The amyloid beta peptide (A beta P) is a small fragment of the much larger, broadly distributed amyloid precursor protein (APP). Abundant A beta P deposition in the brains of patients with Alzheimer's disease suggests that altered APP processing may represent a key pathogenic event. Direct protein structural analyses showed that constitutive processing in human embryonic kidney 293 cells cleaves APP in the interior of the A beta P, thus preventing A beta P deposition. A deficiency of this processing event may ultimately prove to be the etiological event in Alzheimer's disease that gives rise to senile plaque formation.     

Metapopulation dynamics, abundance, and distribution in a microecosystem

The experimental fragmentation of landscapes of a natural ecosystem resulted in declines in the abundance and distribution of most species in the multispecies animal community inhabiting the landscapes and the extinction of many species. These declines caused the deterioration of the positive interspecific relation between local population abundance and distributional extent in this community. However, when patches were connected by habitat corridors, an immigration "rescue effect" arrested declines in both abundance and distribution and maintained the observed positive relation between them. These results demonstrate the importance of metapopulation dynamics and landscape connectivity for the persistence of populations in fragmented landscapes.     

Design, synthesis, and biological activities of arylmethylamine substituted chlorotriazine and methylthiotriazine compounds

Heterocyclic rings were introduced into the core structure of s-triazine to design and synthesize a series of novel triazines containing arylmethylamino moieties. These compounds were characterized by using spectroscopic methods and elemental analysis. Their herbicidal, insecticidal, fungicidal, and antitumor activities were evaluated. Most of these compounds exhibited good herbicidal activity, especially against the dicotyledonous weeds, and compound F8 was almost at the same level as the control compound atrazine. Their structure-activity relationships were discussed. At the same time, some triazines had interesting fungicidal and insecticidal activities, of which F4 exhibited 100% efficacy against Puccinia triticina even at 20 ppm, and F5 showed Lepidopteran-specific activity in both leaf-piece and artificial diet assays. Moreover, these compounds showed antitumor activities against leukemia HL-60 cell line and lung adenocarcinoma A-549 cell line.     

Uptake of drugs from topically applied anti-inflammatory preparations applied to racing animals

Objective To determine whether a drug detected in the blood or urine of a racing animal could have penetrated through the skin from a topically applied preparation.
Design Blood and urine of dogs and horses were analysed after topical administration of three common nonsteroidal anti-inflammatory preparations.
Experimental method Dimethylsulphoxide was analysed using a gas chromatograph with a flame photometric detector. Phenylbutazone, its metabolites and lignocaine were analysed using a gas chromatograph with a mass selective detector.
Results Dimethylsulphoxide, phenylbutazone and ligno-caine were detected in dog urine after muliple applications of the preparations. The maximum concentration of dimethyl-sulphoxide in dog urine correlated with the concentration of dimethylsulphoxide in the preparation. Phenylbutazone penetrated the skin more effectively from the cream than from the solution or gel preparations. This penetration was independent of the concentration of dimethylsulphoxide.
Conclusion The superior penetration of phenylbutazone from the cream can be explained by it being present as a neutral molecule in an hydrophobic medium. It is proposed that phenylbutazone penetrates the skin of greyhounds most effectively by a hydrophobic lipid route which is likely to be different from the path by which dimethylsulphoxide penetrates the skin.     

Hydrographics and the timing of infectious salmon anemia outbreaks among Atlantic salmon (Salmo salar L.) farms in the Quoddy region of Maine, USA and New Brunswick, Canada

Infectious salmon anemia (ISA) has caused severe morbidity and mortality in farmed Atlantic salmon in North America, Norway, Scotland and the Faroe Islands. The Quoddy region of Maine, United States of America (USA), and New Brunswick (NB), Canada is characterized by extensive tidal mixing and close proximity between farms. This region is also prone to recurrent appearances of ISA, though control measures limit disease spread and severity on infected farms. We conducted a retrospective longitudinal analysis of the apparent impact of hydrographics on the incidence and timing of ISA outbreaks on Atlantic salmon (Salmo salar L.) farms in the Quoddy region from May 2002 to August 2004. A time-series cross-sectional regression of 32 farms over 28 months demonstrated a limited, but statistically significant, spatio-temporal clustering of ISA outbreaks linked hydrographically. New outbreaks correlated temporally with those occurring on-site 1 and 3 months prior, and those occurring within one tidal-excursion upstream the same month. Other risk factors included holdover of previous year-class fish, wharf sharing, and possibly harvests of cages infected in previous months. Conclusions suggest that tidal dispersion does play a role in ISAV transmission in the Quoddy region. Dispersal of free virus and/or tidal distribution of lice or other hydrographically influenced vectors or fomites could all contribute to the spatio-temporal patterns described.     

Control of synaptic strength by glial TNFalpha

Activity-dependent modulation of synaptic efficacy in the brain contributes to neural circuit development and experience-dependent plasticity. Although glia are affected by activity and ensheathe synapses, their influence on synaptic strength has largely been ignored. Here, we show that a protein produced by glia, tumor necrosis factor alpha (TNFalpha), enhances synaptic efficacy by increasing surface expression of AMPA receptors. Preventing the actions of endogenous TNFalpha has the opposite effects. Thus, the continual presence of TNFalpha is required for preservation of synaptic strength at excitatory synapses. Through its effects on AMPA receptor trafficking, TNFalpha may play roles in synaptic plasticity and modulating responses to neural injury.     

Spacing uniformity — Yield effects and in-field measurement

Trials were done to investigate the effects of spacing uniformity on crop yield, and to assess a method of measuring spacing uniformity without the need to calculate the coefficient of variation. Spacing uniformities ranged from perfect to the worst observed in a previous field survey. Improved spacing uniformity gave increased marketable yields, with an improvement of 10% in gross return over the worst uniformity treatment. Such improvements are possible in commercial situations with proper attention to equipment maintenance and calibration and uniformity of seed piece size. Spacing uniformity is often measured by the coefficient of variation, which is derived from the mean and standard deviation of measured seed piece or plant spacings. This is not the best method to use, since the measure of uniformity is referenced to the actual spacing, not the desired or target spacing. The alternative method of assessing spacing uniformity involved counting the number of spaces that lie in a pre-determined “acceptable range” and calculating the percentage of “acceptable spaces”. The necessary calculations are easy if a suitable number (e.g. 40 or 50) of seed piece spaces are used.     

Effect of altered carbohydrate traits in hulless barley (Hordeum vulgare L.) on nutrient profiles and availability and nitrogen to energy synchronization

Four hulless barley cultivars (zero-amylose waxy, CDC Fibar; 5%-amylose waxy, CDC Rattan; normal-amylose, CDC McGwire and high-amylose, HB08302) were developed at the Crop Development Centre, University of Saskatchewan, with differences in carbohydrates traits on the basis of amylose (1–20% DM) and β-glucan (5–10% DM) content. The objectives of this research were to determine: 1) the effect of the alteration of these carbohydrate traits in hulless barley on nutrient availability in ruminants, and 2) carbohydrate structure conformation on hourly effective rumen degradation ratio, in comparison with hulled barley-CDC Copeland. Among the hulless barley lines, HB08302 was greater (P < 0.05) in rumen bypass crude protein (BCP: 52.1% CP), effective degradability (ED) of neutral detergent fibre (EDNDF: 74 g/kg DM) than these in CDC Fibar, whereas CDC Fibar showed greater (P < 0.05) effective degradable crude protein (EDCP: 90 g/kg DM) than the other hulless barley lines. Compared with hulless barley, the hulled CDC Copeland showed relatively greater (P < 0.05) BNDF (62.5% NDF or 98 g/kg DM), starch degradation rate (K_d: 17.4%/h) and EDST (75.9% ST) but reduced (P < 0.05) rumen undegradable protein (RUP: 49 g/kg DM). With the respect to hourly effective degradation (ED) ratios, hulless barley cultivars exhibited relatively optimal hourly ED ratios, ranging from 23 to 34 g N/kg CHO, higher than the hulled barley. Among hulless barley cultivars, CDC Fibar and Rattan had the highest (P < 0.05) ratios (34 g N/kg CHO), while the ratio for CDC McGwire (23 g N/kg CHO) was the lowest (P > 0.05). In conclusion, hulless barley lines with altered carbohydrate traits have the potential to increase rumen nutrient availability to ruminants. The altered carbohydrate conformation of hulless barley affected hourly ED ratios, thus affecting rumen nitrogen to energy synchronization.