Load-based approaches for modelling visual clarity in streams at regional scale.

Reduction of visual clarity in streams by diffuse sources of fine sediment is a cause of water quality impairment in New Zealand and internationally. In this paper we introduce the concept of a load of optical cross section (LOCS), which can be used for load-based management of light-attenuating substances and for water quality models that are based on mass accounting. In this approach, the beam attenuation coefficient (units of m(-1)) is estimated from the inverse of the visual clarity (units of m) measured with a black disc. This beam attenuation coefficient can also be considered as an optical cross section (OCS) per volume of water, analogous to a concentration. The instantaneous 'flux' of cross section is obtained from the attenuation coefficient multiplied by the water discharge, and this can be accumulated over time to give an accumulated 'load' of cross section (LOCS). Moreover, OCS is a conservative quantity, in the sense that the OCS of two combined water volumes is the sum of the OCS of the individual water volumes (barring effects such as coagulation, settling, or sorption). The LOCS can be calculated for a water quality station using rating curve methods applied to measured time series of visual clarity and flow. This approach was applied to the sites in New Zealand's National Rivers Water Quality Network (NRWQN). Although the attenuation coefficient follows roughly a power relation with flow at some sites, more flexible loess rating curves are required at other sites. The hybrid mechanistic-statistical catchment model SPARROW (SPAtially Referenced Regressions On Watershed attributes), which is based on a mass balance for mean annual load, was then applied to the NRWQN dataset. Preliminary results from this model are presented, highlighting the importance of factors related to erosion, such as rainfall, slope, hardness of catchment rock types, and the influence of pastoral development on the load of optical cross section.

Calculation of Abraham solute descriptors from McReynolds gas chromatographic retention data.

Quantitative descriptors of solubility properties are useful in the investigation of a wide variety of chemical and biological phenomena. Several solutes which may be useful in such studies are not suitable because these values have not been previously determined experimentally. Several solute descriptors used in the linear solvation energy relationship developed by Abraham and co-workers have been calculated either algebraically or by multiple linear regression analysis. Values for those descriptors which have been calculated are reported and the methods of calculation of these descriptors are also discussed. It is shown that both methods of determination of missing solute descriptor values agree statistically with each other and that the values reported for the calculated descriptors correlate well with data previously reported for similar homologs.

Revised linear solvation energy relationship coefficients for the 77-phase McReynolds data set based on an updated set of solute descriptors.

Linear solvation energy relationship (LSER) coefficients for the 77-phase McReynolds data set have been recalculated using updated solute descriptors in the revised solvation equation: [equation: see text] These revised LSER coefficients are presented and classified by cluster analysis into groupings of stationary phases which have comparable solubility properties. It was found that the groupings were similar to those proposed by Abraham using the original solvation equation and that any dissimilarities were readily explainable by the grouping methods that were applied. Comparison of the original coefficients with the revised set also shows that several stationary phases which had a statistically insignificant b1 value with the original equation now have significant b1 values when utilizing the revised solvation equation.

Biogenesis and biological function of marine algal oxylipins.

The biogenetic source of most marine algal oxylipins, which are many and of diverse structure, can logically be unified through a common lipoxygenase-derived hydroperoxide to epoxy allylic carbocation transformation. The biological role of oxylipins in algae remains an enigma, although numerous ideas have been put forth. Herein, we hypothesize and provide some evidence for an osmoregulatory role for these metabolites.

PCR-SSCP analysis of the p53 gene in tumours of the adrenal gland.

1. Mutations of the p53 tumour suppressor gene are relatively common in the aetiology of a wide spectrum of tumour types, both sporadic and familial. 2. The majority of mutations of the p53 gene are reported to be in the highly conserved region of exons 5-8. 3. Alterations in exons 4, 5 and 7 of the p53 gene in patients with functional adrenal tumours, including aldosterone-producing adenomas, have recently been described. 4. In the present study PCR-SSCP was used to examine the exons 4-9 of the p53 gene in paired peripheral blood leucocyte and tumour DNA in a variety of adrenal tumours, including aldosterone-producing carcinoma and adenoma (both familial and sporadic), phaeochromocytoma and incidentaloma. 5. No evidence was found for mutations in exons 4-9 of the p53 gene in these varieties of adrenal tumours.

PCR-SSCP analysis of the promoter region of the renin gene in patients with aldosterone-producing adenomas.

1. Aldosterone-producing adenomas (APA) of the adrenal gland may be responsive or un-responsive to the renin-angiotensin system. 2. We have described increased expression of renin mRNA in angiotensin-responsive aldosterone-producing adenomas (AII-R-APA) compared with angiotensin-un-responsive aldosterone-producing adenomas (AII-U-APA) and significantly different allelic frequencies of the BglI, TaqI and HinfI restriction fragment length polymorphisms of the renin gene between the two groups. 3. An area including the 5' flanking region -500 bp from exon 1, exon 1 and intron A contained no gross insertions or deletions when studied by a long polymerase chain reaction technique. 4. In the present study, polymerase chain reaction-single strand conformation polymorphism analysis (PCR-SSCP) revealed no single base pair alteration in the proximal promoter region (-600 bp to transcription start) of the renin gene in patients with APA (either AII-U-APA or AII-R-APA) when compared with normal subjects. 5. Therefore, mutations in this regulatory region do not appear to explain the different levels of renin gene expression observed in these two subtypes of APA.

PCR-SSCP analysis of the angiotensin II type 1 receptor gene in patients with aldosterone-producing adenomas.

1. In patients with primary aldosteronism due to angiotensin-responsive and angiotensin-unresponsive aldosterone-producing adenomas, no differences in the coding region of the angiotensin II type 1 (AT1) receptor gene were observed compared to normal subjects in peripheral blood leucocyte DNA. 2. Furthermore, no differences in the AT1 receptor gene were observed in DNA extracted from tumour tissue of either subgroup. 3. Genotypic and allelic frequencies for an RFLP detected in the coding region of the AT1 receptor gene were not significantly different between normal subjects and patients with aldosterone-producing adenomas as a group, nor between normal subjects and patients of either subgroup when compared with each other. 4. In those patients heterozygous in peripheral blood at the RFLP site, tumour DNA showed the same allelic pattern. 5. In patients with aldosterone-producing adenomas either responsive or unresponsive to the renin-angiotensin system, no differences were detected using SSCP analysis in the coding region of the AT1 receptor gene in peripheral blood or tumour tissue.

Analysis of the renin gene in patients with aldosterone-producing adenomas by polymerase chain reaction-single stranded conformational polymorphisms and long polymerase chain reaction.

1. Angiotensin-responsive aldosterone-producing adenomas (AII-R-APA) have increased expression of renin mRNA compared with angiotensin-unresponsive aldosterone-producing adenomas (AII-U-APA) or normal adrenals. 2. Further, significant associations between the BglI, TaqI and HinfI RFLP and aldosterone responsiveness to the renin-angiotensin system of the two subgroups of patients have been reported. 3. Using the polymerase chain reaction based technique single stranded conformational polymorphism, we detected no alterations in exon 1 of the renin gene in peripheral blood leucocyte DNA from normal AII-U-APA and AII-R-APA subjects. 4. Using long-PCR, we amplified a fragment of the renin gene consisting of a region covering 500 bp upstream of exon 1, exon 1 and intron A. No gross changes in this area of the renin gene were found in the three groups of subjects studied. However this does not exclude small alterations in this area.

The renin gene and aldosterone-producing adenomas.

Approximately one half of the aldosterone-producing adenomas (APA) removed from patients with primary aldosteronism in the Hypertension Unit at Greenslopes Hospital belong to a subgroup in which aldosterone levels are responsive to the renin-angiotensin system (angiotensin-responsive APA; AII-R-APA), unlike classical APAs in which aldosterone is unresponsive (AII-U-APA). Renin mRNA levels in AII-R-APA were elevated when compared with those in AII-U-APA or normal adrenal cortices. Renin mRNA levels in some adrenal cortices surrounding AII-R-APA (but never in AII-U-APA) were raised, suggesting that a genetic defect is not confined to the tumor. Renin gene RFLP analysis in peripheral blood DNA revealed a significant difference in allelic frequencies between patients with AII-R-APA and AII-U-APA, suggesting an association between an alteration in the renin gene and aldosterone responsiveness to the renin-angiotensin system in patients with APAs.

Association of restriction fragment length polymorphism at the atrial natriuretic peptide gene locus with aldosterone responsiveness to angiotensin in aldosterone-producing adenoma.

Primary aldosteronism is an important, potentially curable, form of hypertension. We examined the possible association between restriction fragment length polymorphisms in the atrial natriuretic peptide (ANP) gene and responsiveness of aldosterone to angiotensin II in 59 patients with primary aldosteronism due to aldosterone-producing adenoma (APA). Significant differences in the allelic frequencies of the BglI, TaqI and XhoI polymorphic sites at the ANP gene locus (chromosome 1; 1p36) between angiotensin II-unresponsive and angiotensin II-responsive tumors were observed. Variation in the ANP gene between the two groups may result in altered expression of ANP within the adrenal gland, and may contribute to the biochemical regulation of aldosterone production of these two subgroups of patients with APA.

Renin gene polymorphism associated with aldosterone responsiveness to the renin-angiotensin system in patients with aldosterone-producing adenomas.

1. Aldosterone levels in patients with unilateral aldosterone-producing adenomas may be responsive or unresponsive to the renin-angiotensin system, with the former often previously misdiagnosed as bilateral adrenal hyperplasia. 2. In tumours from patients in the responsive subgroup, renin mRNA is expressed in greater amounts than in tumours from patients in the unresponsive subgroup, or in normal adrenals. 3. We compared the frequency of four renin gene polymorphisms in peripheral blood DNA from the two subgroups and found significant associations between BglI, TaqI and HinfI restriction fragment length polymorphisms (RFLP) and aldosterone responsiveness. 4. Allelic variation in the constitutive renin gene was associated with a specific cause of hypertension.

Renin gene polymorphism associated with aldosterone responsiveness to the renin-angiotensin system in patients with aldosterone-producing adenomas.

Aldosterone-producing adenomas may be responsive or unresponsive to the renin-angiotensin system. In tumours from patients in the responsive subgroup, renin mRNA is expressed in greater amounts than in tumours from patients in the unresponsive subgroup, or in normal adrenals. We compared the frequency of two renin gene polymorphisms in peripheral blood DNA from the two subgroups and found a significant association (allele frequency X2 = 7.67, p < 0.006) between BglI polymorphism and aldosterone responsiveness. This may be a significant determinant of the biochemical behaviour of these tumours.

Effect of positive family history of hypertension on the blood pressure and catecholamine responses to a 6 hour adrenaline infusion.

1. The effects of 6 h infusion of adrenaline (INF-A) or dextrose (INF-D) and of post-infusion cold pressor test (CPT) were compared in normal subjects, with (FH+) and without (FH-) a family history of hypertension. 2. Increased urinary excretion rates suggested facilitated noradrenaline (NA) release during and after INF-A in both FH+ and FH-. 3. Urinary adrenaline (UADR) excretion increased during INF-A, as expected, and was also slightly higher after INF-A than INF-D. 4. The effect of INF-A on systolic blood pressure (SBP) was greater in FH- than in FH+ but diastolic blood pressure (DBP) did not fall as quickly with nocturnal recumbency after INF-A in FH+. 5. A significantly greater response in plasma NA to CPT was seen in FH+ than in FH- after INF-A. A similar trend was also seen after INF-D. 6. Increases in DBP due to CPT were higher in FH+ than in FH- after both infusions. 7. This study provides evidence of increased noradrenergic activity during and after INF-A, and also of a difference in response to sympathetic stimulation between FH+ and FH-.

Investigation of relative humidity effects on the response behavior of a pH indicator-based OWG vapor sensor.

The response of a pH indicator-based optical waveguide sensor was characterized with respect to the effects of relative humidity (RH) on the magnitude of the sensor response, and on the rate of response to both hydrochloric acid and ammonia/ammonium hydroxide vapors. Water vapor constitutes both a chemical and a systematic (optical) interference for the OWG sensor response to hydrochloric acid. Swelling of the polymer films upon exposure to water vapor results in a decrease in the loss of light at the polymer/air interface, resulting in an increase in the sensor signal. In addition, high RH conditions decrease the bromothymol blue indicator response to hydrochloric acid vapor. In contrast, the bromothymol blue indicator response to ammonia increases as the RH increases. High RH levels also increases the rate of diffusion (transport) of hydrochloric acid into (and out of) Nafion films, but does not affect the diffusion rate for poly(vinyl alcohol) polymer films. The RH does not appear to have any significant effect on the rate of transport of ammonia in any of the polymer films studied.

An optical waveguide acid vapor sensor.

An optical waveguide sensor for the detection of acid vapors is described. The chemically sensitive reagent coating consists of bromothymol blue indicator suspended in a Nafion polymer film. The sensor uses a 562 nm LED source and a phototransistor detector. Response to hydrochloric acid and hydrogen sulphide vapours is both rapid and reversible, with an estimated detection limit for hydrogen sulphide of less than 15 ppm. The sensors exhibits generalized response to protonic acid vapours, but does not produce an indicator response to carbon dioxide, even at large concentrations (1100 mg/l.) in the presence of water vapor. The sensor exhibits a systematic interference from water vapor which may be corrected by a different approach, either using a reference sensor (Nafion/no indicator) or by monitoring sensor response at two wavelengths.

Effects of repeated doses of pseudoephedrine on blood pressure and plasma catecholamines in normal subjects and in patients with phaeochromocytoma.

1. Increases in blood pressure (BP) and in plasma noradrenaline concentration (NA) were observed after two doses of a non-prescription decongestant containing pseudoephedrine (PE) in two of three patients with phaeochromocytoma, before but not after removal of the tumour. The pressor response was terminated by oral phenoxybenzamine, and modified by prior exposure to this drug. 2. In eight normal subjects administration of the same two doses prevented falls in BP and in NA usually seen with prolonged recumbency, but neither BP nor NA increased. However, a pressor response was observed in a normal subject with a strong family history of hypertension. 3. Exposure to PE in non-prescription decongestants is not without risk in hypertension.

Evidence for presynaptic beta-adrenoceptor stimulation 24 hours after a 6 hour adrenaline infusion.

1. The effects of 6 h infusions of adrenaline (INF-A) and dextrose (INF-D) were compared in nine normal subjects. 2. A significant increase in systolic blood pressure was observed during INF-A compared with INF-D and, 24 h after infusion, diastolic blood pressure was higher after INF-A than after INF-D. 3. Heart rate (HR) was significantly higher during INF-A than during INF-D. 4. As expected, plasma ADR increased significantly during INF-A but, unexpectedly, remained elevated 60 min post infusion compared with INF-D. Levels during activity the next morning were somewhat higher after INF-A, but not significantly different from INF-D. 5. Plasma NA increased transiently during INF-A and decreased during INF-D. Urinary NA was significantly higher during INF-A than during INF-D, and insignificantly higher during overnight recumbency, consistent with enhanced noradrenergic transmission.

Potassium, glucose, insulin interrelationships during adrenaline infusion in normotensive and hypertensive humans.

1. Significant increases in arterial noradrenaline (NA) of similar magnitude were seen in normotensive (NT) and hypertensive humans (HT) during adrenaline (ADR) infusion. 2. Significant falls in plasma potassium (K+) were observed in both NT and HT during ADR infusion, even at rates equivalent to minor stress. Levels achieved were significantly lower in HT than in NT. 3. Plasma glucose increased significantly in HT at all ADR infusion rates but only at higher rates of infusion in NT. 4. Basal insulin levels were significantly higher in NT than in HT. After cessation of infusion, insulin increased three-fold in HT and two-fold in NT. 5. Infusion of ADR to produce levels seen during mild to moderate stress resulted in significant increases in plasma NA, falls in plasma K+ and increases in plasma glucose. The expected large insulin response to rising glucose was not seen until after ADR was ceased, confirming the inhibitory effect of ADR on glucose stimulated insulin release.

Discovery of the mammalian insulin release modulator, hepoxilin B3, from the tropical red algae Platysiphonia miniata and Cottoniella filamentosa.

The insulin release enhancer, 10-hydroxy-11,12-trans-epoxy-5(Z),8(Z),14(Z)-icosatrienoic acid (hepoxilin B3), is a 12-lipoxygenase metabolite of arachidonic acid that has been found in various mammalian tissues. Although lipoxygenase pathways are well documented in terrestrial plants, this lipoxygenase product has never been isolated from the plant kingdom. Herein, we report the first isolation of this lipoxygenase product, hepoxilin B3, from two plants, the tropical red marine algae Platysiphonia miniata (C. Agardh) Børgesen and Cottoniella filamentosa Børgesen. Furthermore, through application of two-dimensional NMR methodology to the structural description of this algal natural product, we demonstrate the tremendous power of this technique in this chemical class.