The effect of dexamethasone on albumin production by fetal rat hepatocytes in culture

Hepatocytes derived from 15 and 19-day gestation rats synthesize and secrete albumin during culture. Albumin secretion is maintained when the culture medium is supplemented with dexamethasone but declines in its absence. The fall in secretion rate correlates with the level of albumin messenger RNA in the respective cultures. Even when dexamethasone is present, the level of albumin production in 19-day gestation hepatocytes is 6 to 7 times greater than that observed in hepatocytes derived from 15-day gestation rats. Immunocytochemical studies were undertaken to establish whether the difference in secretion rate was due to a difference in the amount of albumin produced by all the hepatocytes of the respective cultures or whether there were fewer hepatocytes which were capable of synthesizing albumin in the less mature liver. The results indicate that albumin production is reduced in all hepatocytes when cultured in the absence of dexamethasone.     

Potential Distribution of the Australian Native Chloris truncata Based on Modelling Both the Successful and Failed Global Introductions

Our aim was to model the current and future potential global distribution of Chloris truncata (windmill grass) based on the plant's biology, soil requirements and colonisation success. The growth response of C. truncata to constant temperatures and soil moisture levels were measured and estimated respectively, to develop parameters for a CLIMEX bioclimatic model of potential distribution. The native distribution in eastern Australia and naturalised distribution in Western Australia was also used to inform the model. Associations with soil types were assessed within the suitable bioclimatic region in Australia. The global projection of the model was tested against the distribution of soil types and the known successful and failed global introductions. The verified model was then projected to future conditions due to climate change. Optimal temperature for plant development was 28°C and the plant required 970 degree-days above a threshold of 10°C. Early collection records indicate that the species is native to Queensland, New South Wales and Victoria. The plant has been introduced elsewhere in Australia and throughout the world as a wool contaminant and as a potential pasture species, but some of the recorded establishments have failed to persist. The CLIMEX model projected to the world reflected effectively both the successful and failed distributions. The inclusion of soil associations improved the explanation of the observed distribution in Australia, but did not improve the ability to determine the potential distribution elsewhere, due to lack of similarity of soil types between continents. The addition of a climate change projection showed decreased suitability for this species in Australia, but increased suitability for other parts of the world, including regions where the plant previously failed to establish.     

Arrayed primer extension: a robust and reliable genotyping platform for the diagnosis of single gene disorders: beta-thalassemia and thiopurine methyltransferase deficiency

Mutation screenings, which were conventionally carried out individually because of different assay conditions, are usually time consuming and not cost effective. Using microarray technology, simultaneous molecular diagnosis of multiple mutations on a single platform is possible. To evaluate this idea, we developed a DNA chip platform to simultaneously detect 23 mutations of the beta-globin gene and 9 mutations of thiopurine methyltransferase (TPMT) gene based on the principle of arrayed primer extension (APEX). A blinded test consisting of 200 DNA samples with known genotypes was performed to validate this strategy. High genotyping accuracy of 97.3% and 100% for beta-globin and TPMT genes, respectively, were achieved. Further analysis on the fluorescent intensity demonstrated clear separation between the real signal and the background noise, which enabled us to set two cutoff values (V(lower) = 4.0 and V(upper) = 12.0) to determine the genotype quantitatively. Our results showed that APEX is a highly reliable genotyping strategy to detect mutations that cause beta-thalassemia or TPMT enzyme deficiency.     

Skeletal muscle mass and exercise performance in stable ambulatory patients with heart failure

Lang, Chim C., Don B. Chomsky, Glenn Rayos, T. K. Yeoh, andJohn R. Wilson. Skeletal muscle mass and exercise performance instable ambulatory patients with heart failure. J. Appl. Physiol. 82(1): 257-261, 1997.The purposeof this study was to determine whether skeletal muscle atrophy limitsthe maximal exercise capacity of stable ambulatory patients with heartfailure. Body composition and maximal exercise capacity were measuredin 100 stable ambulatory patients with heart failure. Body compositionwas assessed by using dual-energy X-ray absorption. Peak exerciseoxygen consumption (O_{2 peak}) and theanaerobic threshold were measured by using a Naughton treadmillprotocol and a Medical GraphicsCardioO₂ System.O_{2 peak} averaged 13.4 ± 3.3 ml ^· min^{1 ·} kg¹or 43 ± 12% of normal. Lean body mass averaged 52.9 ± 10.5 kg and leg lean mass 16.5 ± 3.6 kg. Leg lean mass correlated linearly with O_{2 peak}(r= 0.68, P < 0.01), suggesting that exerciseperformance is influenced by skeletal muscle mass. However, lean bodymass was comparable to levels noted in 1,584 normal control subjects, suggesting no decrease in muscle mass. Leg muscle mass was comparable to levels noted in 34 normal control subjects, further supporting thisconclusion. These findings suggest that exercise intolerance in stableambulatory patients with heart failure is not due to skeletal muscleatrophy.

     

An enzyme-bound linamarin indicator paper strip for the semi-quantitative estimation of linamarin

Summary An enzyme-bound linamarin indicator paper strip was developed which was based on the hydrolysis of linamarin by cassava leaf linamarase and the detection of the cyanide released by alkaline picrate reagent. The linamarase could be stabilized with gelatin or gelatin in combination with polyvinylpyrrolidone-10 or trehalose. A positive reaction was observed within 15 minutes at 37°C and it could detect linamarin concentration as low as 0.5 to 1 mM. The indicator strip could be used to estimate linamarin content in cassava semiquantitatively.     

Host Range ofBrachycaudus rumexicolens(Patch), an Aphid Associated with the Polygonaceae

The aphidBrachycaudus rumexicolensis a recent arrival in Australia where the weedsEmex australis, E. spinosa,andRumexspecies are its recorded hosts. Host range on 114 species representing 42 plant families was assessed in the laboratory to determine the aphid species' potential as a biological control agent againstE. australis.Survival and reproductive success were measured in clip and/or dialysis-tube cages.B. rumexicolensdeveloped most successfully onEmexspp. andRumexspp. and to a lesser extent on other Polygonaceae.Lupinus albus(white lupin) andTriticum aestivum(wheat) were the only non-Polygonaceae plants on whichB. rumexicolensdeveloped to a degree similar to its usual hosts. At a field site in Western Australia,E. australisandPolygonum avicularewere the only Polygonaceae present and the primary host species ofB. rumexicolens.At peak abundance, it was found on other pasture and crop species, but at considerably lower numbers than on its Polygonaceae hosts. It was concluded that this was due to local migration and that populations would not be sustained on non-Polygonaceae plants. It was also concluded that the risk of virus transmission would not be increased by the presence ofB. rumexicolenson nonhosts.B. rumexicolensis considered sufficiently safe to use in programs aimed at augmenting the impact of biological control agents on the weedE. australis.     

Characterisation of worldwide Helicobacter pylori strains reveals genetic conservation and essentiality of serine protease HtrA

HtrA proteases and chaperones exhibit important roles in periplasmic protein quality control and stress responses. The genetic inactivation of htrA has been described for many bacterial pathogens. However, in some cases such as the gastric pathogen Helicobacter pylori, HtrA is secreted where it cleaves the tumour‐suppressor E‐cadherin interfering with gastric disease development, but the generation of htrA mutants is still lacking. Here, we show that the htrA gene locus is highly conserved in worldwide strains. HtrA presence was confirmed in 992 H. pylori isolates in gastric biopsy material from infected patients. Differential RNA‐sequencing (dRNA‐seq) indicated that htrA is encoded in an operon with two subsequent genes, HP1020 and HP1021. Genetic mutagenesis and complementation studies revealed that HP1020 and HP1021, but not htrA, can be mutated. In addition, we demonstrate that suppression of HtrA proteolytic activity with a newly developed inhibitor is sufficient to effectively kill H. pylori, but not other bacteria. We show that Helicobacter htrA is an essential bifunctional gene with crucial intracellular and extracellular functions. Thus, we describe here the first microbe in which htrA is an indispensable gene, a situation unique in the bacterial kingdom. HtrA can therefore be considered a promising new target for anti‐bacterial therapy.     

Carbon dioxide fixation in orchid aerial roots

Acidity fluctuation, CO₂ gas exchange, δ¹³C value, PEP carboxylase and RuBP carboxylase activities in aerial roots of selected thick-leaved orchid hybrids ( Arachnis and Aranthera ) were studied. Both aerial roots and leaves showed acidity fluctuation over a 24 h period. Dark acidification in aerial roots was enhanced at low temperature (15°C). Aerial roots had δ¹³C values close to those of leaves which have been previously demonstrated to possess crassulacean acid metabolism. Variation in δ¹³C values along the length of the roots was observed; the root tip having a less negative δ¹³C value (—13.34%‰) than the older portions of the roots (—14.55%‰). There was no net CO₂ fixation by aerial root, although ¹⁴³²CO₂ fixation was observed in light and in darkness. The pattern of fluctuation in activities of PEP carboxylase and RuBP carboxylase in aerial roots was similar to that obtained for the leaves. In both aerial roots and leaves, PEP carboxylase activity was several times higher than that of RuBP carboxylase.     

Simultaneous fingerprint and high‐wavenumber fiber‐optic Raman spectroscopy enhances real‐time in vivo diagnosis of adenomatous polyps during colonoscopy

Colorectal cancer can be prevented if detected early (e.g., precancerous polyps‐adenoma). Endoscopic differential diagnosis of hyperplastic polyps (that have little or no risk of malignant transformation) and adenomas (that have prominent malignant latency) remains an unambiguous clinical challenge. Raman spectroscopy is an optical vibrational technique capable of probing biomolecular changes of tissue associated with neoplastic transformation. This work aims to apply a fiber‐optic simultaneous fingerprint (FP) and high wavenumber (HW) Raman spectroscopy technique for real‐time in vivo assessment of adenomatous polyps during clinical colonoscopy. We have developed a fiber‐optic Raman endoscopic technique capable of simultaneously acquiring both the FP (i.e., 800–1800 cm^–1) and HW (i.e., 2800–3600 cm^–1) Raman spectra from colorectal tissue subsurface (<200 µm) for real‐time assessment of colorectal carcinogenesis. In vivo FP/HW Raman spectra were acquired from 50 patients with 17 colorectal polyps during clinical colonoscopy. Prominent Raman spectral differences (p < 0.001) were found between hyperplastic (n = 118 spectra), adenoma (n = 184 spectra) that could be attributed to changes in inter‐ and intra‐cellular proteins, lipids, DNA and water structures and conformations. Simultaneous FP/HW Raman endoscopy provides a diagnostic sensitivity of 90.9% and specificity of 83.3% for differentiating adenoma from hyperplastic polyps, which is superior to either the FP or HW Raman technique alone. This study shows that simultaneous FP/HW Raman spectroscopy technique has the potential to be a clinically powerful tool for improving early diagnosis of adenomatous polyps in vivo during colonoscopic examination.