bluuebunny/crossref_metadata_2025 huggingface dataset:
Antiviral treatment for the control of pandemic influenza: some logistical constraints
Authors: Arinaminpathy N , McLean A.R
Published: August 2007

Disease control programmes for an influenza pandemic will rely initially on the deployment of antiviral drugs such as Tamiflu, until a vaccine becomes available. However, such control programmes may be severely hampered by logistical constraints such as a finite stockpile of drugs and a limit on the distribution rate. We study the effects of such constraints using a compartmental modelling approach.

We find that the most aggressive possible antiviral programme minimizes the final epidemic size, even if this should lead to premature stockpile run-out. Moreover, if the basic reproductive number
R
0
is not too high, such a policy can avoid run-out altogether. However, where run-out would occur, such benefits must be weighed against the possibility of a higher epidemic peak than if a more conservative policy were followed.

Where there is a maximum number of treatment courses that can be dispensed per day, reflecting a manpower limit on antiviral distribution, our results suggest that such a constraint is unlikely to have a significant impact (i.e. increasing the final epidemic size by more than 10%), as long as drug courses sufficient to treat at least 6% of the population can be dispensed per day.
Strategies for guided-wave structural health monitoring
Authors: Croxford A.J , Wilcox P.D , Drinkwater B.W , Konstantinidis G
Published: August 2007

Structural health monitoring (SHM) using guided waves is one of the only ways in which damage anywhere in a structure can be detected using a sparse array of permanently attached sensors. To distinguish damage from structural features, some form of comparison with damage-free reference data is essential, and here subtraction is considered. The detectability of damage is determined by the amplitude of residual signals from structural features remaining after the subtraction of reference data. These are non-zero due to changing environmental conditions such as temperature. In this paper, the amplitude of the residual signals is quantified for different guided-wave SHM strategies. Comparisons are made between two methods of reference signal subtraction and between two candidate sensor configurations. These studies allow estimates to be made of the number of sensors required per unit area to reliably detect a prescribed type of damage. It is shown that the number required is prohibitively high, even in the presence of modest temperature fluctuations, hence some form of temperature compensation is absolutely essential for guided-wave SHM systems to be viable. A potential solution is examined and shown to provide an improvement in signal suppression of approximately 30 dB, which corresponds to two orders of magnitude reduction in the number of sensors required.
Wave arrival singularities at cuspidal points in the acoustic wave surfaces of anisotropic solids and their unfolding under weak spatial dispersion
Authors: Every A.G , Kaplunov J.D , Pichugin A.V , Rogerson G.A
Published: August 2007

This paper is concerned with wave arrival singularities in the elastodynamic Green's functions of infinite anisotropic elastic solids, and their unfolding into smooth wave trains, known as quasi-arrivals, through spatial dispersion. The wave arrivals treated here are those occurring in (i) the displacement response to a suddenly applied point force or three-dimensional Green's function,, and (ii) the displacement response to an impulsive line force or two-dimensional Green's function,. These arrivals take on various analytical forms, including step function and logarithmic and power-law divergences. They travel outwards from the source at the group velocities in each direction, and their locus defines the three- and two-dimensional acoustic wave surfaces, respectively. The main focus of this paper is on the form of the wave arrivals in the neighbourhood of cuspidal points in the wave surfaces, and how these arrivals unfold into quasi-arrivals under the first onset of spatial dispersion. This regime of weak spatial dispersion, where the acoustic wavelength,λ, begins to approach the natural length scale,l, of the medium, is characterized by a correction to the phase velocity, which is quadratic in the wavevector,k, and the presence of fourth-order spatial derivatives of the displacement field in the wave equation. Integral expressions are established for the quasi-arrivals near to cuspidal points, involving the Airy function in the case ofand the Scorer function in the case of. Numerical results are presented, illustrating the oscillatory nature of the quasi-arrivals and the interference effects that occur near to cuspidal points in the wave surface.
Fracture propagation in brittle granular matter
Authors: Einav Itai
Published: August 2007

It is nearly a century since Alan Arnold Griffith developed his energy criterion for the fracture propagation of cracks in ‘near-continuous’ solids. Needless to say that his celebrated work has revolutionized the world of material science. In a very succinct way, Griffith connected between three important aspects of the fracture process: (i) the material, (ii) the stress level, and (iii) the geometry of the crack. Nothing similar was developed for brittle granular matter, although in these materials fracture propagates in the sense of comminution. Recently, I have developed an energy theory, called breakage mechanics, based on the concept of breakage. However, the analogy between the mechanics of breakage and fracture is missing. Here I establish this relation using energy principles and derive a critical comminution pressure for brittle granular materials. This critical pressure is surprisingly complementary to Griffith's critical tensile stress for near-continuous materials. This step enables for the first time to apply the principles of fracture mechanics to all disciplines dealing with confined particles comminution such as geophysics, geology, geotechnical engineering, mineral processing, agriculture and food industry, pharmaceutics and powder technology.
Recent postglacial range expansion drives the rapid diversification of a songbird lineage in the genusJunco
Authors: Milá Borja , McCormack John E , Castañeda Gabriela , Wayne Robert K , Smith Thomas B
Published: August 2007

Pleistocene glacial cycles are thought to have played a major role in the diversification of temperate and boreal species of North American birds. Given that coalescence times between sister taxa typically range from 0.1 to 2.0 Myr, it has been assumed that diversification occurred as populations were isolated in refugia over long periods of time, probably spanning one to several full glacial cycles. In contrast, the rapid postglacial range expansions and recolonization of northern latitudes following glacial maxima have received less attention as potential promoters of speciation. Here we report a case of extremely rapid diversification in the songbird genusJuncoas a result of a single continent-wide range expansion within the last 10 000 years. Molecular data from 264 juncos sampled throughout their range reveal that as the yellow-eyed junco (Junco phaeonotus) of Mesoamerica expanded northward following the last glacial maximum, it speciated into the dark-eyed junco (Junco hyemalis), which subsequently diversified itself into at least five markedly distinct and geographically structured morphotypes in the USA and Canada. Patterns of low genetic structure and diversity in mitochondrial DNA and amplified fragment length polymorphism loci found in dark-eyed juncos relative to Mesoamerican yellow-eyed juncos provide support for the hypothesis of an expansion from the south, followed by rapid diversification in the north. These results underscore the role of postglacial expansions in promoting diversification and speciation through a mechanism that represents an alternative to traditional modes of Pleistocene speciation.
Disentangling hybridization and host colonization in parasitic roundworms of humans and pigs
Authors: Criscione Charles D , Anderson Joel D , Sudimack Dan , Peng Weidong , Jha Bharat , Williams-Blangero Sarah , Anderson Timothy J.C
Published: August 2007

Knowledge of cross-transmission and hybridization between parasites of humans and reservoir hosts is critical for understanding the evolution of the parasite and for implementing control programmes. There is now a consensus that populations of pig and humanAscaris(roundworms) show significant genetic subdivision. However, it is unclear whether this has resulted from a single or multiple host shift(s). Furthermore, previous molecular data have not been sufficient to determine whether sympatric populations of human and pigAscariscan exchange genes. To disentangle patterns of host colonization and hybridization, we used 23 microsatellite loci to conduct Bayesian clustering analyses of individual worms collected from pigs and humans. We observed strong differentiation between populations which was primarily driven by geography, with secondary differentiation resulting from host affiliation within locations. This pattern is consistent with multiple host colonization events. However, there is low support for the short internal branches of the dendrograms. In part, the relationships among clusters may result from current hybridization among sympatric human and pig roundworms. Indeed, congruence in three Bayesian methods indicated that 4 and 7% of roundworms sampled from Guatemala and China, respectively, were hybrids. These results indicate that there is contemporary cross-transmission between populations of human and pigAscaris.
Culling-induced social perturbation in Eurasian badgers
Meles meles
and the management of TB in cattle: an analysis of a critical problem in applied ecology
Authors: Carter Stephen P , Delahay Richard J , Smith Graham C , Macdonald David W , Riordan Philip , Etherington Thomas R , Pimley Elizabeth R , Walker Neil J , Cheeseman Chris L
Published: August 2007

The Eurasian badger (
Meles meles
) is implicated in the transmission of bovine tuberculosis (TB) to cattle in the UK and Republic of Ireland. Badger culling has been employed for the control of TB in cattle in both countries, with varying results. Social perturbation of badger populations following culling has been proposed as an explanation for the failure of culling to consistently demonstrate significant reductions in cattle TB. Field studies indicate that culling badgers may result in increased immigration into culled areas, disruption of territoriality, increased ranging and mixing between social groups. Our analysis shows that some measures of sociality may remain significantly disrupted for up to 8 years after culling. This may have epidemiological consequences because previous research has shown that even in a relatively undisturbed badger population, movements between groups are associated with increases in the incidence of
Mycobacterium bovis
infection. This is consistent with the results from a large-scale field trial, which demonstrated decreased benefits of culling at the edges of culled areas, and an increase in herd breakdown rates in neighbouring cattle.
ROLE OF INTEGRINS IN ENTEROCYTE MIGRATION
Authors: Basson Marc D
Published: August 2007

1. Enterocyte motility depends critically on cell–matrix interactions. Although still incompletely understood, these appear critically dependent upon integrin‐mediated cell adhesion.

2. In addition to providing a mechanism for cell adhesion and traction, the integrins are likely to serve as true receptors for the matrix across which cell motility occurs, initiating signals by both mechanical and chemical means that alter cell phenotype and proliferation as well as cell motility.

3. Sound rationale now exists to postulate that soluble growth factors within the extracellular milieu regulate intestinal mucosal healing not only directly but also indirectly by modulating integrin expression and organization.

Presented at the Experimental Biology Symposium on the Role of Integrins in Acute Renal Failure, New Orleans, Louisiana, USA, 1997.
ABOLITION OF DRUG‐INDUCED EARLY AFTERDEPOLARIZATIONS BY POTASSIUM CHANNEL ACTIVATORS IN GUINEA‐PIG PURKINJE FIBRES
Authors: Brosch SF , Studenik C , Heistracher P
Published: August 2007

1. Drug‐induced early afterdepolarizations (EAD) are considered to be the underlying mechanism of the polymorphic ventricular dysrhythmia Torsades de pointes. Sotalol and disopyramide are well known to generate EAD. Therefore, it was of interest to study the effects of potassium channel activators, such as nicorandil, pinacidil and lemakalim, on those drug‐induced EAD in spontaneously beating guinea‐pig Purkinje fibres using the intracellular microelectrode technique.

2. Early afterdepolarizations induced by sotalol at concentrations of 80 and 160 μmol/L could be completely abolished by nicorandil at concentrations between 50 and 500 μmol/L. The extracellular K+ concentration was 2.7 mmol/L.

3. Disopyramide‐induced EAD at concentrations of 10, 20 and 30 μmol/L in a Tyrode’s solution containing 1.35 mmol/L K+ and these EAD were abolished by pinacidil (30 and 100 μmol/L) and lemakalim (10 and 30 μmol/L).

4. Early afterdepolarizations could be regenerated by superfusion of Purkinje fibres with K+ channel activator‐free Tyrode’s solution containing either sotalol or disopyramide.

5. Our results demonstrate that drug‐induced EAD can be abolished by K+ channel activators and, therefore, may provide anti‐arrhythmic effects in heart diseases.
CHRONIC CALCITONIN ADMINISTRATION AND RENAL CALCIUM TRANSPORT IN THE RAT
Authors: Carney Shane L , Thompson Lisa
Published: August 2007

1. While calcitonin (CT) has now been clearly demonstrated to be a renal Ca2+‐conserving hormone and may share similar transport mechanisms with parathyroid hormone (PTH), the effect of prolonged CT exposure on renal Ca2+ transport has not been evaluated.

2. Consequently, a submaximal and maximal Ca2+‐conserving concentration of human CT was infused into groups of anaesthetized acutely thyroparathyroidectomized rats that had been treated with twice daily subcutaneous human (h) CT at a low or high dose or vehicle for 12 days.

3. The maximal hCT infusion (10 μg bolus and per hour) produced a marked inhibitory effect on renal Ca2+ excretion in vehicle‐treated rats, with the fractional excretion rate of Ca2+ being reduced from 4.49±0.31 to 1.39±0.23% (P<0.001). However, in rats pretreated with high concentrations of hormone (0.25 μg hCT) twice daily for 12 days, marked Ca2+ conservation was measured (fractional excretion 1.09±0.18%), which was not altered by the additional intravenous administration of maximal hCT.

4. Renal Mg2+ transport was similarly altered by hCT administration, without any evidence that prolonged CT inhibited renal Mg2+ transport. The increase in glomerular filtration rate caused by hCT also appeared to persist with repeated hormone administration. The fractional excretion of Na+ and PO4 was significantly increased by high‐ but not low‐dose hCT treatment and was not altered by the addition of a maximal hormone dose at day 12.

5. The present study failed to demonstrate any down‐ regulation of the response to prolonged hCT administration when renal Ca2+ and Mg2+ transport was measured. If renal escape does occur with CT, as has been suggested but not proven with PTH, other mechanisms, such as hormone production or release, may be responsible.
5‐HYDROXYTRYPTAMINE‐INDUCED CONTRACTION OF THE MARMOSET AORTA IS MEDIATED BY A 5‐HT1‐LIKE RECEPTOR
Authors: Frewin SM Dyer, IS de la Lande, DB , Head RJ
Published: August 2007

1. 5‐Hydroxytryptamine (5‐HT) exerts both contractile and relaxant effects in the marmoset isolated aorta, actions that are unaffected by the 5‐HT2 antagonist ketanserin. The aim of the present study was to define the receptors mediating the contractile activity of 5‐HT in the marmoset aorta.

2. Contractile responses were elicited in aortic rings that were either: (i) precontracted submaximally with the thromboxane A2 agonist U44069 in order to amplify the responses; or (ii) exposed to Nω‐nitro‐L‐arginine (100 μmol/L) plus LY 53857 (0.1 μmol/L; a 5‐HT2 receptor antagonist shown previously to inhibit relaxation). The effect of 5‐HT on adenosine 3′,5′‐cyclic monophosphate (cAMP) formation was also investigated.

3. The effects of agonists and antagonists comprised: (i) agonist potencies in the order 5‐carboxamidotryptamine > 5‐HT > sumatriptan > 8‐hydroxy‐2‐(di‐n‐propylamino)tetralin; (ii) inhibition of contractile action of 5‐HT by the 5‐HT1D antagonist GR 127935; (iii) a contractile response to methysergide; (iv) a lack of effect of tropisetron, an antagonist of 5‐HT3 and 5‐HT4 receptors; and (v) inhibition of forskolin‐stimulated cAMP formation by 5‐HT (in the presence of LY 53857), indicative of negative coupling to adenylate cyclase.

4. The above effects fulfil the criteria for a 5‐HT1‐like receptor. In view of the previous finding that this contractile response is insensitive to ketanserin, it is concluded that the contractile effects of 5‐HT in the marmoset aorta are mediated exclusively by a 5‐HT1‐like receptor.
DEXAMETHASONE‐INDUCED CHANGES IN ENDOMETRIAL GROWTH AND INDUCIBLE NITRIC OXIDE SYNTHASE DURING DECIDUALIZATION IN RATS
Authors: Spencer Fitzgerald , Chi Limen , Zhu Ming‐Xia
Published: August 2007

1. The present study investigated the time‐dependent inhibitory responses of endometrial growth and inducible nitric oxide synthase (iNOS) to dexamethasone during deciduoma development that was surgically induced on day 4 of pseudopregnancy (PG).

2. Groups of rats (n = 6) were subcutaneously injected with dexamethasone (1.5 mg/rat per day) for 3 days (PG days 1–3, 4–6, 7–9, 10–12 and 12–15). Rats in each group were killed on the last injection day.

3. Dexamethasone produced comparable temporal inhibitory changes in endometrial growth (wet weight, protein and DNA concentrations; P<0.0001) and in iNOS activity (130 kDa protein band), which peaked after PG days 4–6 and 7–9 pretreatments.

4. Endometrial matrix metalloproteinases (72 and 92 kDa) activity profiles displayed maximal reductions (36 and 53%, respectively) following PG days 4–6 pretreatment. Serum progesterone levels were equally (P<0.0001) but asynchronously inhibited by dexamethasone on PG days 9 and 12.

5. Dexamethasone inhibition of endometrial growth and in situ iNOS was most pronounced during decidual development (PG days 4–9). Minor reductions in these endometrial parameters occurred before deciduoma induction (PG days 1–3) and during deciduoma regression (PG days 10–15).

6. These results indicate that, in the endometrium, the iNOS/ endogenous nitric oxide system may be linked to the biochemical and metabolic mechanisms responsible for the developmental responsiveness of the deciduoma to dexamethasone exposure. These time‐dependent changes in endometrial growth and iNOS apparently were not mediated by progesterone.
ANGIOTENSIN II RECEPTORS IN CARDIAC LEFT VENTRICLES OF DAHL RATS
Authors: Sumida Yoichi , Umemura Satoshi , Kobayashi Shun‐ichi , Kihara Minoru , Tamura Kouichi , Ishigami Tomoaki , Ochiai Hisao , Chiba Eiko , Nyui Nobuo , Ishii Masao
Published: August 2007

1. Dahl Iwai salt‐sensitive (DS) rats have been reported as becoming hypertensive with left ventricular hypertrophy (LVH) and heart failure when on a high‐salt diet. Their circulating renin–angiotensin system (RAS) has been reported to be suppressed. To evaluate the role of angiotensin II (AngII) type 1 and type 2 receptors (AT1 and AT2, respectively) in LVH, we compared cardiac AT1 and AT2 receptors in 10‐week‐old DS rats and Dahl Iwai salt‐resistant (DR) rats.

2. Seven pairs of 6‐week‐old male DS and DR rats were fed either a low‐ or high‐salt diet (0.3 or 8% NaCl, respectively) for 4 weeks. Left ventricular AngII receptors were measured by radioligand binding assays using [125I]‐[Sar1,Ile8]‐AngII in plasma membrane fractions from these four groups. The AT1 and AT2 receptors were distinguished using their specific antagonists CV 11974 and PD 123319, respectively.

3. The high‐salt diet increased blood pressure and the left ventricle:bodyweight ratio in DS rats. However, neither Bmax for AT1 and AT2 receptors nor Kd for [125I]‐[Sar1,Ile8]‐AngII differed between the groups. These results are different from those of other reports of pressure‐overload LVH, such as spontaneously hypertensive rats or renovascular hypertension rats, in which AT1 and AT2 receptors were reported to be up‐regulated.
COSEGREGATION OF THE Tnfα LOCUS WITH CARDIOVASCULAR PHENOTYPES IN THE F2 GENERATION OF A NEW ZEALAND GENETICALLY HYPERTENSIVE AND BROWN NORWAY CROSS
Authors: Harris Eugenie L , Grigor Murray R , Thompson Caryn M
Published: August 2007

1. The association of the Tnfα locus with several cardiovascular phenotypes and body mass has been studied in the F2 generation of a reciprocal cross between rats of the New Zealand genetically hypertensive (GH) and the normotensive Brown Norway (BN) strains. In the total F2 population the GH allele of Tnfα cosegregated with increased intra‐arterial blood pressure (BP) in a recessive manner. A similar but weaker effect was observed for tail BP.

2. An association between genotype and body mass in females with GH grandfathers was also detected.

3. An association between genotype and pulse rate was observed for females.

4. This work supports other evidence pointing to an association of a gene (or genes) on rat chromosome 20 with hypertension.
EPITHELIAL CELL SHEDDING IN ACUTE RENAL INJURY
Authors: Racusen Lorraine C
Published: August 2007

1. To address the postulate that sublethally injured tubular cells may be shed from renal epithelium while still viable, studies were undertaken in vivo in human ‘acute tubular necrosis’ and in rabbit models of renal tubular injury.

2. Substantial numbers of viable tubular cells were voided in the urine. When placed in culture, these cells gave rise to monolayers, confirming viability. The majority of intact cells demonstrated markers of proximal tubule.

3. In vitro studies of human renal proximal tubular cells exposed to hypoxia/anoxia showed rounding and retraction associated with disruption of actin microfilaments. Phalloidin stabilized the filaments and prevented the changes in cell shape indicative of altered adherence.

Presented at the Experimental Biology Symposium on the Role of Integrins in Acute Renal Failure, New Orleans, Louisiana, USA, 1997.
POISONING AND EPIDEMIOLOGY: ‘TOXICOEPIDEMIOLOGY’
Authors: Buckley Nicholas A
Published: August 2007

1. There is little hypothesis‐testing clinical research performed in toxicology. Randomized clinical trials are rare and most observational studies are performed on highly selected patients and are subject to marked bias. Thus, for many poisonings, our approach has been based almost entirely on deduction from known pharmacological/toxicological effects, generalizations from drugs within the same therapeutic class, animal data and case reports. This is also far from satisfactory, as many toxicological mechanisms are poorly understood and not related to the therapeutic class.

2. Although we need much better data to address the clinical and public health aspects of poisoning, there are many practical and ethical reasons why randomized clinical trials are difficult in this field. However, the scope for observational research, in particular population‐based clinical epidemiology, is almost unlimited. The collection of data on human poisoning is facilitated because most non‐fatal overdoses are admitted to hospital and by legal requirements to report to the coroner deaths that are due to poisoning. In the present article I argue that ‘toxicoepidemiology’, meaning the application of epidemiological methods to the problem of acute poisoning, is the best means we have of addressing deficiencies in our knowledge of poisoning.

3. Examples are given of a variety of observational research strategies, ranging from audit to meta‐analysis, that may be applied to clinical toxicology. From coronial and clinical data obtained from reasonably well‐defined populations, it has been possible to identify a number of previously unrecognized differences in the severity and spectrum of toxicity between and within drug classes. Also, the demographic risk factors for poisoning and the reproducibility, validity and optimal use of diagnostic and therapeutic interventions can be assessed.

4. The major limitations to the range of associations and interventions that may be studied are the need to achieve adequate power to study uncommon outcomes or poisonings and the ability to replicate findings at other centres using similar methodology. The expansion of data collection to other centres has the potential largely to overcome these obstacles.
ENHANCED SENSITIVITY OF MEDULLARY DEPRESSOR NEURONS TO N‐METHYL‐D‐ASPARTATE–GLYCINE SITE ANTAGONISTS IN THE SPONTANEOUSLY HYPERTENSIVE RAT
Authors: Kapoor Ranjna , Kapoor Vimal
Published: August 2007

1. The effects of the specific N‐methyl‐D‐aspartate (NMDA)–glycine site antagonist 5‐fluoro indole‐2‐carboxylic acid (FICA) and NMDA, microinjected into the vasodepressor caudal ventrolateral medulla, were compared in spontaneously hypertensive rats (SHR) and in Wistar‐Kyoto (WKY) rats.

2. 5‐Fluoro indole‐2‐carboxylic acid elicited a significant pressor response (+20.0±4.9 mmHg) in SHR, but no change was found in the basal blood pressure of WKY rats.

3. The depressor response due to NMDA microinjection was significantly larger in SHR (–48.0±4 mmHg) than in WKY rats (–23.0±1.9 mmHg).

4. Pre‐injection of FICA attenuated the depressor effects of NMDA significantly, this blockade being significantly more pronounced in SHR (37.0±2.7 mmHg) than in WKY rats (12.0± 1.2 mmHg).

5. The enhanced responses to FICA may reflect the lower levels of the endogenous NMDA–glycine antagonist kynurenic acid in SHR compared with WKY rats.
ABSENCE OF DETECTABLE REGRESSION OF HUMAN HYPERTENSIVE LEFT VENTRICULAR HYPERTROPHY FOLLOWING DRUG TREATMENT FOR 1 YEAR
Authors: Laufer Eljas , Reid Christopher , Qi X Ling , Jennings Garry L
Published: August 2007

1. The present study was designed to compare and contrast the effects of 1 year’s treatment with angiotensin‐converting enzyme inhibition (captopril 25–100 mg daily) and beta‐blockade (atenolol 50–100 mg daily) on hypertensive cardiac structure and function as well as the other established cardiovascular risk factors of high blood pressure (BP), lipid profile and blood glucose.

2. This was a prospective randomized open drug trial with blinded end‐point echocardiographic and cardiac Doppler assessment in 37 subjects who had primary essential hypertension and left ventricular hypertrophy of captopril (n = 20) versus atenolol (n = 17), adding hydrochlorothiazide if BP was not controlled by 1 month. Multiple time point measurements throughout the 1 year treatment period of the study were made of BP, echocardiographic parameters of cardiac structure and function, as well as lipid profile and blood glucose.

3. There were no significant between‐group differences for captopril or atenolol with regard to BP (at baseline (mean ± SD) 154.0/101.1 ± 13.3/5.1 and 152.5/101.8 ± 10.0/5.8 mmHg, respectively) which was normalized by 1 month (138.7/85.6 ± 18.8/11.7 and 135.4/88.5 ± 16.9/9.5 mmHg, respectively) in both treatment groups (both P < 0.01 vs baseline). Also, there were no between‐group or within‐group differences for any of the measures of left ventricular hypertrophy or systolic function throughout the 12 month treatment period; however, captopril alone significantly increased left ventricular early diastolic filling (P < 0.05 vs baseline) at most of the measured time points. Furthermore, there were no significant between‐ or within‐group differences with regard to metabolic (lipids and glucose) profile over the 1 year treatment period of the present study.

4. Markers of cardiovascular risk, including BP, echocardiographic measures of left ventricular hypertrophy, lipid profile and blood glucose were not significantly different between therapies. Despite good BP control by 1 month, neither drug regimen regressed left ventricular hypertrophy. However, captopril significantly increased left ventricular early diastolic filling after 3 months of treatment.
EFFECT OF EXPERIMENTAL DIABETES MELLITUS ON GENTAMICIN‐INDUCED ACUTE RENAL FUNCTIONAL CHANGES IN THE ANAESTHETIZED RAT
Authors: Garland K Hamilton, EJ Eaton, HO , Old S
Published: August 2007

1. Rats with streptozotocin (STZ) diabetes are protected from gentamicin (GEN) nephrotoxicity. Because the chronic renal damage from GEN is preceded by acute renal functional changes (notably hypercalciuria), the present study aims to determine whether diabetes may also protect against the acute effects of the drug. If there is a link between the rapid physiological actions of GEN and its subsequent nephrotoxicity, the former may also be affected by the diabetic condition.

2. Standard renal clearance techniques were performed on anaesthetized rats that had been injected with STZ or vehicle 2 weeks previously. All animals were infused with 0.9% NaCl for 5 h and then either GEN (0.28 mg/kg per min) or 0.9% NaCl alone for 2 h.

3. Baseline fractional calcium excretion (FECa) of diabetic rats was three‐fold that of control animals (6.6±0.2 vs 2.2±0.2%, respectively; P<0.01, MANOVA). Following GEN infusion, a comparable increase in FECa occurred in control and diabetic rats (5.3±0.6 vs 5.3±0.8%, respectively; NS).

4. Streptozotocin diabetes, therefore, does not alter the acute hypercalciuric response to GEN. This may suggest that the acute effects of GEN on renal calcium handling do not contribute to the subsequent nephrotoxicity. However, the higher baseline FECa seen in diabetic rats may afford protection against the renal injury caused by gentamicin.
RATES OF GROWTH, RESPIRATION AND PHOTOSYNTHESIS OF UNICELLULAR ALGAE AS RELATED TO CELL SIZE—A REVIEW1,2
Authors: Banse Karl
Published: August 2007

The decline of growth rate with increasing species size of unicellular algae grown under uniform conditions is quantified by applying to published data the equation, growth, (cell · time)−1= a (cell carbon)b where a and b are coefficients. The degree of size‐dependence might be highest under optimal conditions of growth where b is 0.75. Respiration rate is shown to decline with size in the same manner. It is postulated that gross photosynthesis and processes underlying growth are similarly size‐dependent. Growth, efficiency (net over gross photosynthesis) cannot be shown to be size‐dependent. Cell size, expressed as carbon, is proposed as a scaling factor in comparative algal physiology.
POLYMORPHISM OF THE DIATOM PINNULARIA BREBISSONII IN CULTURE AND A FIELD COLLECTION1,2
Authors: Hostetter H. P. , Rutherford Kenneth D.
Published: August 2007

Two clones ofPinnularia brebissonii(Kütz.) Rabh. var.brebissoniiwere established and maintained in logarithmic phase of growth. Initial length of the cells was 37 μm. As cell division occurred, the mean length of cells in each population decreased as predicted by the MacDonald‐Pfitzer hypothesis; however, the decrease in mean length was not uniform throughout the growth period. This nonuniformity is probably caused by nonrandom division of cells in the population or by a changing increment of size reduction due to division. The initial increment of size reduction was calculated as 0.7 μm/division. The smallest, cells observed were 8 μm long. As cells decrease in length, cell volume decreases and the proportion of cells with aberrant valve structure increases. More than 90% of the valves were abnormal in a population with mean length of 14 μm. The abnormalities of structure involved the raphe, the central area and the striae.
SEROLOGICAL STUDIES OF MALE AND FEMALE STRAINS OFEUDORINA ELEGANS(CHLOROPHYCEAE)1,2
Authors: Herbst D. S. , Kemp C. L.
Published: August 2007

Male and female strains ofEudorina elegansEhrenberg were examined by serological methods for flagellar and cellular antigenic differences. No significant differences could be detected between the strains by using agglutination, immobilization and diffusion tests. However, differentiated sperm were neither agglutinated nor immobilized by anti‐vegetative cell sera.
STIMULATION OF GROWTH IN SCENEDESMUS OBLIQUUS (CHLOROPHYCEAE) BY HUMIC ACIDS UNDER IRON LIMITED CONDITIONS1,2
Authors: Giesy John P.
Published: August 2007

Stimulatory affects of humic acids of molecular weight 30,000 or greater on iron‐starved Scenedesmus obliquus (Turp.) Kütz. in association with bacteria were studied by growth and Fe uptake experiments. Humic acids stimulated growth of Fe‐starved cells by decreasing the lag phase and extending the growth phase. Humic acids stimulated increased algal growth in medium containing EDTA as well as in medium containing no EDTA, indicating humic acids are not stimulating algal growth under Fe limiting conditions by creating a soluble Fe pool. Humic acids decreased Fe availability to Fe‐starved S. obliquus. Iron bound to humic acids is unavailable for uptake by Fe‐starved cells indicating growth stimulation is not due to chelation effects alone. Stimulation of growth is not a membrane phenomenon as humic acids show the same stimulatory effect when in contact with cells or separated by dialysis membrane. Humic acids also stimulate growth in the dark, with and without aeration, indicating use as a heterotrophic substrate. A photoheterotrophic mechanism is indicated by increased algal growth caused by illuminating cultures, containing humic acids but excluding CO2.
GROWTH RESPONSES TO SALINITY VARIATION IN FOUR ARCTIC ICE DIATOMS1,2
Authors: Grant W. S. , Horner Rita A.
Published: August 2007

During spring, extensive blooms of microalgae grow on the underside of arctic sea ice. The brownish, algal layer penetrates ca. 2 cm into the bottom surface of the ice and the algae are potentially exposed to very high salinities. Four diatom species, Melosira juergensii Ag., Porosira glacialis (Grun.) Jørg., Navicula transitans var. derasa (Grun.) Cleve, and Coscinodiscus lacustris Grun., isolated from, sea ice samples taken from the Beaufort and Chukchi seas near Barrow, Alaska, were grown at 11 salinities ranging from 5 to 70‰ at 5 C under constant illumination. All of the species grew at 5‰ except N. transitans whose lower growth limit was 15‰. Growth was high over a broad range of salinities, but none of the species grew at salinities above 60‰. These diatom species appear to be well suited to tolerate the salinities in the brine pockets near the bottom of annual arctic sea ice where they are found. High brine‐cell salinity, however, may limit the upward, penetration of ice algae into the bottom of sea ice.
PHOTOSYNTHETIC CAPACITY AND LUXURY UPTAKE OF CARBON DURING PHOSPHATE LIMITATION IN PEDIASTRUM DUPLEX (CHLOROPHYCEAE)1
Authors: Lehman John T.
Published: August 2007

When cells of Pediastrum duplex Meyen experience phosphorus depletion, their capacity for carbon fixation declines, but sizes and carbon contents of the cells increase several‐fold, an apparent instance of “luxury uptake” of carbon. Maximum rates of uptake of phosphate increase during the same period, and are consequently correlated with the enlarged surface area of the cells. Thus the disadvantage of increased cell volume, which may accelerate sinking speed in nature, is offset by the increased capacity of the cells for nutrient uptake.
PHOSPHATE UPTAKE KINETICS INEUGLENA GRACILIS(Z) (EUGLENOPHYCEAE) GROWN ON LIGHT/DARK CYCLES.' I. SYNCHRONIZED BATCH CULTURES1
Authors: Chisholm S. W. , Stross R. G.
Published: August 2007

The characteristics of phosphate uptake in synchronized populations ofEuglena gracilisKlebs (Z) were studied. The cells were grown autotrophically in batch culture and synchronized with a cycle of 14:10 LD.

Incorporation of P was nonlinear with time for the first 2 h of incubation over a wide range of P concentrations and completely inhibited by darkness. The kinetics of P uptake as a function of P concentration were triphasic between 0 and 100 μM PO4, obeying Michaelis‐Menten kinetics over the 0–3 μM PO4range‐only. Uptake velocity increased linearly with, concentration above 3 μM PO4.

The kinetics of P uptake varied with stage in the cell cycle. The half‐saturation constant for uptake at the lower concentrations oscillated between 0.7 and 2.8 μM PO4, reaching a peak immediately before the onset of cell division (beginning of the dark period).Vmaxwas largest in the middle of the light period, as was the slope of the linear portion of the kinetic pattern. Further analysis of the kinetics suggests that changes in this slope are responsible for the oscillation inKsvalues calculated for the lower concentrations. This analysis assumes 2 uptake mechanisms, one which saturates at low concentrations of phosphate, and one which is nonsaturable over the entire concentration range examined.
PHOSPHATE UPTAKE KINETICS IN EUGLENA GRACILIS (Z) (EUGLENOPHYCEAE) GROWN IN LIGHT/DARK CYCLES. II. PHASED PO4‐LIMITED CULTURES1
Authors: Chisholm S. W. , Stross R. G.
Published: August 2007

The characteristics of phosphate uptake and photosynthetic capacity were studied in P‐limited populations of Euglena gracilis Klebs (Z), using both P‐limited batch cultures in stationary phase and cyclostat cultures grown on 14:10 LD.

P uptake obeyed Michaelis‐Menten kinetics between 0 and 150 μM PO4 under both growth conditions. The value of Vmax was 35% lower in the dark than in the light in the stationary phase cells. The value of K8 was not affected by light conditions, and uptake was completely inhibited in the presence of 1 mm KCN.

P uptake (at 2.0 μM PO4) and photosynthetic capacity showed diel periodicity with peak rates occurring just before the beginning of the dark period for P uptake, and 8 h into the light period for photosynthetic capacity. Vmax for P uptake increased by a factor of 1.5 over the light period, whereas K8 remained constant at 1.4 μM PO4. These patterns were displayed by both nondividing stationary phase cells and populations in which less than a third of the cells divided each day, indicating that the rhythmicity is not coupled to cell division.
THE RELEASE, SETTLEMENT AND GERMINATION OF ZOOSPORES INCHORDA TOMENTOSA(PHAEOPHYCEAE, LAMINARIALES)1,2
Authors: Tolh Ronald
Published: August 2007

Details of zoospore germination inChorda tomentosaLyngb. are outlined. Uninucleate zoospores, when released are embedded in a mucilaginous mass of carbohydrate which dissolves and the biflagellate zoospores become motile. The long anterior flagellum is composed of a highly coiled terminal region and a rigid lower section bearing mastigonemes. The rigid, short posterior flagellum lacks mastigonemes. After initial contact by the tightly coiled region of the anterior flagellum, the zoospore draws itself to the substrate by flagellar resorbtion. After deposition of 3 wall layers the germling produces a germ tube. During this time the disc‐shaped chloroplast enlarges undergoing changes in shape. As the germ tubes reach ca. 15 μm they cease forward growth and swell at their tips. The majority of cytoplasm of the original zoospore moves into the tube. Just before the nucleus enters the tube, centriole replication occurs. Mitosis is presumed to take place somewhere in the germ tube so that at 24 h, 2‐celled gametophytes are produced.
SIMULTANEOUS ASSIMILATION OF AMMONIUM AND NITRATE BY GELIDIUM NUDIFRONS (GELIDIALES: RHODOPHYTA)1
Authors: Bird Kimon T.
Published: August 2007

Simultaneous assimilation of NH4 and NO3 by Gelidium nudifrons Gardner was observed in culture experiments of 4 possible combinations of NH4 and NO3. The combinations tested were those in which the concentration of both N sources were in the range of 3.0–4.0 μg‐atN · l−1; both in the range of 0.5–1.0 μg‐atN · l−1; one in the 3.0–4.0 μg‐atN · l−1 range and the other in the 0.5–1.0 μg‐atN · l−1 range; and, visa versa. The data suggest that the pools of both NH4 and NO3 are simultaneously available for algal assimilation.
CHLOROPHYLL A VERSUS ADENOSINE TRIPHOSPHATE AS ALGAL BIOMASS INDICATORS IN LAKES1
Authors: Paerl Hans W. , Tilzer Max M. , Goldman Charles R.
Published: August 2007

The relation between phyloplankton chlorophyll a and adenosine triphosphate (ATP) was investigated during a yearly cycle in Lake Tahoe, California–Nevada, and a variety of North American and New Zealand lakes of ranging trophic state. Since cellular concentrations of ATP have been shown as acceptable indicators of live biomass among natural microbial populations, the ratio of chlorophyll a to cellular ATP reveals the extent of pigment production per unit biomass under diverse environmental conditions.

In general, mixed systems, i.e., epilimnion of most lakes sampled, showed good consistency of cellular chlorophyll a:ATP ratios. Under thermally stratified conditions at Lake Tahoe extensive modifications of the ratio occurred, leading to a 10‐fold increase in the ratio at the bottom of the euphotic zone by late summer. Thus, the applicability of chlorophyll a as a quantitative algal biomass indicator is greatly restricted in lakes having thermally stratified euphotic zones.
THE DESMID GENERASPHAEROZOSMA, ONYCHONEMAANDTEILINGIA: AN HISTORICAL APPRAISAL1
Authors: Kirk William L. , Postek Michael T. , Cox Elenor R.
Published: August 2007

The taxonomic history of the desmid generaOnychonemaWallich,SphaerozosmaCorda andTeilingiaBourrelly is reviewed. In addition, Teiling's studies on asymmetry applied toOnychonemaandSphaerozosmaare considered. Observations based on SEM examination of one species each ofOnychonemaand ofSphaerozosmaare presented to show morphological differences. Finally, an appraisal of the taxonomic proposals by Telling and Bourrelly is given.
BIOCHEMICAL TAXONOMY OF MARINE PHYTOPLANKTON BY ELECTROPHORESIS OF ENZYMES. I. THE CENTRIC DIATOMS THALASSIOSIRA PSEUDONANA AND T. FLUVIATILIS1,2
Authors: Murphy Lynda S. , Guillard Robert R. L.
Published: August 2007

Diatom systematics depends almost entirely upon structure of the silica shell. It is not known to what extent the taxonomic species, as defined by shell structure, corresponds to the genetic species—i.e., to the reproductively isolated population. As an approach to this problem, we report here a comparison of enzymes by electrophoresis. We have examined the genetic constitution of a number of clones of (presumably) the same species for each of 2 closely related, centric diatom species: Thalassiosira pseudonana Hasle and Heimdal and T. fluviatilis Hustedt. The 4 clones of T. fluviatilis form a distinct group, clearly separated from all the T. pseudonana clones. Within T. pseudonana, 4 estuarine clones and one reef clone form a group that is distinctly different from 4 oceanic clones. A single clone of T. pseudonana from the Continental Slope waters is intermediate between these 2 groups and probably shares genes with both groups, indicating that the 2 T. pseudonana groups are not genetically isolated. We conclude that i) within groups, isolates are closely related even though they originated from different continents; and, ii) T. pseudonana is subdivided into ecological races.
PRESCOTTIELLA, A NEW GENUS OF ASYMMETRICAL DESMIDS (CHLOROPHYCEAE)1
Authors: Bicudo Carlos E. M.
Published: August 2007

Bipolar asymmetry has been considered a morphological characteristic sufficient for differentiation of genera among the Desmidiaceae. Therefore, Micrasterias sudanensis Grönbl., Prowse & Scott, the only species of Micrasterias showing such asymmetry, is made the type of a new genus, Prescottiella, gen. nov.
STICTYOSIPHON SORIFERUS (PHAEOPHYTA, DICTYOSIPHONALES) FROM EASTERN NORTH AMERICA1
Authors: South G. Robin , Hooper Robert
Published: August 2007

Although earlier North American records of Stictyosiphon soriferus (Reinke) Rosenvinge cannot he substantiated, the species is shown to be common in Newfoundland and is also reported from Nova Scotia. Plants are summer annuals and a component of ephemeral subtidal communities characteristic of suitable inlets and harbors. Only plurilocular reproductive organs are produced. In culture the life history of populations from both sides of the North Atlantic consists of a direct replication by asexual zoospores. A microscopic stage might occur in the field, and is presently known only from European cultures. In eastern Canada S. soriferus is readily distinguishable from S. tortilis (Rupr.) Reinke, S. subsimplex Holden and S. griffithsianus (Le Jol.) Holmes & Batters.
THE LIFE HISTORY OF COLEOCHAETE SCUTATA (CHLOROPHYCEAE) STUDIED BY A FEULGEN MICROSPECTROPHOTOMETRIC ANALYSIS OF THE DNA CYCLE1,2
Authors: Hopkins Archibald W. , McBride Gordon E.
Published: August 2007

The life history of Coleochaete scutata Bréb. was analyzed by Feulgen microspectrophotometry, a technique measuring DNA content in individual nuclei. By correlating nuclear DNA content with morphological structures or stages in the life history, changes in ploidy level are revealed.

The microspectrophotometric study confirmed the earlier reports of a haploid vegetative thallus with mitotic division restricted primarily to the margin of the thallus. In the mitotic cycle the G1 (pre‐synthesis) phase is longer in duration than the synthesis find G2 (post‐synthesis) phases. Oogamous sexual reproduction results in resistant oospores which attain DNA levels of 2C 8C (1C being the DNA level of gamete nuclei).
NITRATE REDUCTASE ACTIVITY OF AMPHIDINIUM CARTERI AND CACHONINA NIEI (DINOPHYCEAE) IN BATCH CULTURE: DIEL PERIODICITY AND EFFECTS OF LIGHT INTENSITY AND AMMONIA1,2
Authors: Hersey Ronald L. , Swift Elijah
Published: August 2007

The activity of extracted NADH‐NO3− reductase was measured in the marine dinoflagellates Amphidinium carteri Hulburt and Cachonina niei Loeblich. Its activity showed a diel periodicity and was ca. twice as great at midday as at midnight. The enzyme activity was unstable, with an in vitro half‐life of 2–3 h. Values of enzyme activity were low or undetectable during lag phase but paralleled the instantaneous growth rate value during log phase. Nitrate reductase activity was not found in the stationary phase of growth, but additions of NO3− resulted in enzyme activity after 24h. When A. carteri was exposed to a series of light intensities for several weeks, the division rate and enzyme activity increased with increasing light intensity up to saturating intensities. In 6 h exposures, enzyme activity decreased with decreasing light intensities below light intensities saturating division rate. Additions of NH4+ (0.5–50 μm) to A. carteri cultures decreased the amount of extractable enzyme. The in vitro activity was not inhibited by similar NH+4 concentrations.
SIDEROCHROMES IN CYANOPHYCEAE: ISOLATION AND CHARACTERIZATION OF SCHIZOKINEN FROM ANABAENA SP.1
Authors: Simpson Frank B. , Neilands J. B.
Published: August 2007

Schizokinen, a high affinity iron transport compound (siderochrome), previously described from Bacillus megaterium, has been isolated and characterized from low‐iron cultures of a bluegreen alga, Anabaena sp. No conclusive evidence for production of an iron‐repressible hydroxamate or catechol type siderochrome was observed in certain other bluegreen algae, such as Anabaena cylindrica Lemm., Coccochloris peniocystis (Kütz.) Drouet & Daily, Anacystis sp., Gloeocapsa alpicola (Lyng.) Born. or Chroococcus sp.
PHOSPHOTUNGSTIC ACID‐CHROMIC ACID: A SELECTIVE STAIN FOR ALGAL PLASMA MEMBRANES1,2
Authors: Sundberg Ingrid , Lembi Carole A.
Published: August 2007

A phosphotungstic acid‐chromic acid mixture selectively stains the plasma membrane of whole cells of selected members of the Chlorophyceae, Charophyceae, Euglenophyceae, Xanthophyceae, Bacillariophyceae, Chrysophyceae, and Rhodophyceae, and the plasma membrane in cell‐free fractions of Mougeotia (Chlorophyceae). The procedure is not effective on the plasma membrane of the cyanophycean Scytonema or the cyanophycean endosymbiont of Glaucocystis. Staining of the cell walls of Chlamydomonas, Bangia, and Scytonema and the pellicle and sliding junction of Euglena and Astasia suggest that PTA‐CrO3 reactivity may be associated with glycoproteins in the cell walls and plasma membranes.