Dependence of the functional capacity of the cardiorespiratory system on the body mass in patients with coronary heart disease

The influence of excessive body mass on the development of cardiorespiratory deficiency was studied in patients with coronary heart disease (CHD). Basic parameters of hemodynamics and gas exchange were measured during a graded exercise test. In the CHD patients with excessive body mass, mean blood pressure, cardiac output, left ventricular power output, and left ventricular posterior wall thickness were significantly increased even at rest. During exercise, these patients displayed an increase in myocardial energy consumption and peripheral vascular resistance. It was concluded that an excess in body mass is critical when the increase in the body mass index (Quetelet’s index) exceeds the norm by 20%.     

Salt tolerance and survival thresholds for two species of Antarctic soil nematodes

We evaluated the response of the Antarctic soil nematodes Scottnema lindsayae and Plectus antarcticus to various salts (NaCl, MgSO₄, KNO₃ and NaCl + MgSO₄) and salt concentrations in prepared salt solutions ranging from 0.1 to 3 M, and in saturation paste extracts of soils collected from multiple locations where nematode abundance varied from zero to numerous, and where electrical conductivity ranged from 108 to >12,000 μS/cm. Nematode salt tolerance was salt specific; both nematode species survived in low-experimental concentrations of NaCl and MgSO₄, and neither species survived in KNO₃ solutions of any concentration. There was no survival of nematodes in the saturation paste extracts of highly saline soils (4,100 μS/cm), while survival was over 80–97% in less saline soils (1,945 μS/cm). A 1:1 dilution of these highly saline saturation paste extracts increased S. lindsayae survival to 80%, while survival of P. antarcticus was not observed until dilutions of greater than 200%. The results complement previous studies demonstrating niche partitioning of S. lindsayae and P. antarcticus across salinity gradients and strengthen interpretations of the physiological mechanisms underlying previously reported spatial correlation between soil salinity and nematodes abundance in the Antarctic Dry Valleys.     

The application of acoustic Doppler current profilers to measure the timing and patterns of coral larval dispersal

An experiment was conducted along the reefs off west Maui, Hawaii, during the summer of 2003 to monitor the spawning of the reef-building coral Montipora capitata and to determine the role of ocean currents in dispersing the larvae from the natal reef. Instruments documented the environmental forcing during the coral spawning season; drifters were deployed on three successive nights following direct observations of coral spawning. Both the timing and relative magnitude of the coral spawning were identifiable in acoustic backscatter data and correlated to plankton tow data. Each drifter track showed that the surface water containing coral eggs and planula larvae were transported rapidly offshore and not locally retained. Wind and current patterns during the previous year and during subsequent coral spawning events later in the summer were similar to those observed during the drifter releases. This suggests that the trajectories observed during the focused experiment are representative of the general pattern of larval dispersal off west Maui. These findings demonstrate the application of acoustic profilers for remotely imaging coral spawning and predicting their initial dispersal patterns.     

Darwin Medal presentation: Corals-seeking the big picture

Recipients of Darwin Medals from the International Society of Reef Studies are requested to write an overview of the work that led to their award. This account is a personal perspective of thirty-five years work on corals. The fields of taxonomy, biogeography, palaeontology, molecular biology, and evolution are presented in an historical context. Emphasis is given to the changing relevance of these fields to today’s world of information technology and the ever-increasing conservation needs.     

Taurine deficiency in maned wolves (Chrysocyon brachyurus) maintained on two diets manufactured for prevention of cystine urolithiasis

This study assesses the long‐term effects of an experimental diet vs. a commercially available manufactured diet, intended to reduce clinical disease related to cystinuria, on the taurine status of captive maned wolves. For 13 weeks, two pairs of maned wolves were maintained on the commercially available maintenance diet, whereas two individually housed wolves were maintained on the experimental diet. All six wolves, at the beginning and at the end of the diet trial, had severely decreased plasma concentrations of taurine (as compared to the normal canine reference range of 60–120 nmol/ml) (National Research Council [2003] National Academies Press) with average taurine concentrations of 16 nmol/ml at the beginning of the study and 3 nmol/ml at the end of the study. There was no statistically significant difference in the taurine concentrations between animals on the maintenance vs. experimental diets. Both diets were supplemented subsequently with taurine at a concentration of 0.3%. All study animals were eventually switched to the taurine‐supplemented version of the commercially manufactured maintenance diet and subsequent samplings were carried out to monitor plasma taurine concentrations. A final sampling, carried out approximately 5 months after the initiation of taurine supplementation, showed an average taurine concentration within the target canine reference range (90.25 nmol/ml). There are numerous physiologic (e.g., possible unique metabolism and requirements for taurine in this species as compared to other canids) and dietary factors (e.g., effects of the types and concentrations of fiber and protein on nutrient availability, taurine metabolism, and enterohepatic circulation of taurine‐conjugated bile salts; impaired taurine synthesis secondary to low cysteine availability) that could be potential contributors to the development of taurine deficiency in the maned wolves in this study. Taurine supplementation should be considered in maned wolves maintained on diets intended for reduction of cystinuria‐related complications. Zoo Biol 0:1–14, 2005. © 2005 Wiley‐Liss, Inc.     

Raman and infrared spectroscopic and theoretical studies of dinuclear rhenium and osmium complexes, M2(O2CCH3)4X2 (M = Re, Os; X = Cl, Br)

Infrared, far-infrared and Raman spectra of Re₂(O₂CCH₃)₄X₂ (X = Cl, Br) and Re₂(O₂CCD₃)₄Cl₂ have been recorded. Assignments of the vibrational spectra of Os₂(O₂CCH₃)₄Cl₂ and its deuterated derivative have been completed together with the Re complexes on the basis of normal-coordinate analysis. Force constant calculation was made for the acetate ion as well as for a four-atomic unit (with the CH₃ and CD₃ groups considered as point masses) using optimized masses of 16.7, 17.8, 20.5 and 21.6 for ¹²CH₃, ¹³CH₃, ¹²CD₃ and ¹³CD₃ groups, respectively. The force constants of the acetate ion have been adopted to the starting force field of the M₂(O₂CCH₃)₄X₂ type complexes. The metal-halide (0.889, 0.997 and 1.286 N cm⁻¹) and metal-metal stretching (3.32, 3.34 and 3.57 N cm⁻¹) force constants were obtained for Re₂(O₂CCH₃)₄Cl₂Re₂(O₂CCH₃)₄Br₂ and Os₂(O₂CCH₃)₄Cl₂ complexes, respectively. It was shown that the so-called diatomic approximation in most cases overestimates the M-M stretching force constants by 30-40%. Much better correlation has been obtained to fit these force constants, which produced values very close to those obtained by full normal-coordinate calculations. The Re-Re stretching force constants showed a reasonable correlation with the Re-Re bond distances for 18 rhenium complexes.     

Defoliation of Centaurea solstitialis Stimulates Compensatory Growth and Intensifies Negative Effects on Neighbors

Efforts to arrest the spread of invasive weeds with herbivory may be hindered by weak effects of the herbivores or strong compensatory responses of the invaders. We conducted a greenhouse experiment to study the effects of defoliation and soil fungi on competition between the invasive weed Centaurea solstitialis and C. solstitialis and Avena barbata, a naturalized Eurasian annual grass, and Nassella pulchra, a native California bunchgrass. Surprisingly, considering the explosive invasion of grasslands by C. solstitialis, Avena and Nassella were strong competitors and reduced the invader’s biomass by 80.2% and 80.1% over all defoliation and soil fungicide treatments, respectively. However, our experiments were conducted in artificial environments where competition was probably accentuated. When fungicide was applied to the soil, the biomass of C. solstitialis was reduced in all treatment combinations, but reduction in the biomass of the invader had no corollary impact on the grasses. There was no overall effect of defoliation on the final biomass of C. solstitialis as the invader compensated fully for severe clipping. In fact, the directional trend of the clipping effect was +6.4% over all treatments after eight weeks. A significant neighbor × soil fungicide × clipping effect suggested that the compensatory response was the strongest without soil fungicide and when C. solstitialis was alone (+ 19%). Our key finding was that the compensatory response of C. solstitialis in all treatments was associated with an increase in the weed’s negative effects on Nassella and Avena – there was a significant decrease in the total biomass of both grasses and the reproductive biomass of Avena in pots with clipped C. solstitialis. Our results were obtained in controlled conditions that may have been conducive to compensatory growth, but they suggest the existence of mechanisms that may allow C. solstitialis, like other Centaurea species, to resist herbivory.     

Cytochromes P450 in gibberellin biosynthesis

The gibberellins (GAs) are an important class of plant growth regulators that are active in many aspects of plant growth and development. GAs are synthesized by a complex pathway involving three enzyme classes spanning different subcellular compartments. One of these enzyme classes is the cytochrome P450s which catalyze a number of oxidation steps in the middle part of the pathway. Mutants in these cytochrome P450-mediated steps in a number of species have been crucial in isolating the genes encoding these enzymes and have also played an important role in understanding GA physiology. GAs are also synthesized by fungi, in a biosynthesis pathway largely catalyzed by cytochrome P450s. The fungal pathway appears to have evolved independently to that of higher plants.

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Laser scanning cytometer-based assays for measuring host cell attachment and invasion by the human pathogen Toxoplasma gondii.

BACKGROUND: Toxoplasma gondii is among the most common protozoan parasites of humans. Both attachment to and invasion of host cells by T. gondii are necessary for infection, yet little is known about the molecular mechanisms underlying these processes. T. gondii's etiological importance and its role as a model organism for studying invasion in related parasites necessitate a means to quantitatively assay host cell attachment and invasion. METHODS: We present here Laser Scanning Cytometer (LSC)-based assays of T. gondii invasion and attachment. The invasion assay involves automated counting of invaded and non-invaded parasites, differentially labeled with distinct fluorochromes. The attachment assay compares the relative binding of differentially labeled parasites. The assays were evaluated using treatments known to decrease invasion or attachment. RESULTS: The LSC-based assays are robust and reproducible, remove operator bias, and significantly increase the sample size that can be feasibly counted compared to other currently available microscope-based methods. In the first application of the new assays, we have shown that parasites attach to fixed and unfixed host cells using different mechanisms. CONCLUSIONS: The LSC-based assays represent useful new methods for quantitatively measuring attachment and invasion by T. gondii, and can be readily adapted to study similar processes in other host-pathogen systems.