bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of Armillaria root disease on lodgepole pine tree growth
Authors: Mallett K I , Volney WJA
Published: April 2011

Growth of lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) trees infected with Armillaria ostoyae (Romagn.) Herink growing in disease centres were compared with the growth of uninfected trees from two stands in west-central Alberta. Sample trees were measured (height, diameter at breast height, and height to live crown) and disks removed for stem analysis. The standing wood volumes inside disease centres of the two sites were 54 and 15% of the volume in surrounding stands. There were no significant differences in height or diameter at breast height between infected and uninfected trees. Expected growth rates determined by stem analysis revealed, however, that there were conservative losses of 43% in annual volume increment, 32% in specific volume increment, and 23% in height increment. The pattern of stem growth of infected individuals was that typically found in open-grown trees, in marked contrast to the pattern found in uninfected trees growing outside the disease centre. Tree growth chronologies suggested that disease centres were present early in the stands' development as trees grew rapidly before they became infected; however, the characteristic open-grown pattern of trees found in disease centres did not change after they became infected.
Effects of defoliation and cutting in eastern oak forests on Armillaria spp. and a competitor, Megacollybia platyphylla
Authors: Burrill E A , Worrall J J , Wargo P M , Stehman S V
Published: April 2011

Gypsy moth (Lymantria dispar L.) and Armillaria root rot interact to cause extensive mortality in eastern oak forests. Defoliation by gypsy moth weakens trees and increases their susceptibility to Armillaria root rot. Partial cutting prior to defoliation has been proposed as a management technique because it may increase tree vigor and the ability to withstand defoliation stress. However, cutting could also increase inoculum potential of Armillaria by providing a resource, the residual stumps. Megacollybia platyphylla (Pers.:Fr.) Kotl. & Pouz. is a native, cord-forming, saprobic fungus that may compete with Armillaria for resources such as stumps, snags and debris. A factorial treatment design with three levels of cutting and three levels of defoliation was used to examine the effects of cutting and defoliation on the two fungi. Among uncut stands, defoliated stands had significantly greater colonization of resource units by Armillaria than nondefoliated stands. However, stands that were cut prior to defoliation had significantly less Armillaria colonization and significantly more M. platyphylla colonization than those that were not cut. Armillaria colonized snags better than stumps and colonized least well in debris, where M. platyphylla showed its best colonizing performance. The data suggest that cutting mitigates the effects of defoliation on colonization by Armillaria and are consistent with the hypothesis that M. platyphylla plays a role in such mitigation.
Decomposition rate constants of Picea abies logs in southeastern Norway
Authors: Næsset Erik
Published: April 2011

Decomposition rate constants were estimated from 384 cross sections of Norway spruce (Picea abies (L.) Karst.) logs with base diameter >7.0 cm collected in open areas at five different study sites in southeastern Norway. Fresh wood core samples were taken from 95 standing trees adjacent to the logs to estimate the initial density of these cross sections. Based on this chronosequence, a simple negative exponential function of time showed an average decomposition rate constant for all cross sections of 0.033 per year. Cross-section diameter, ground contact, soil moisture, and aspect were all found to have significant impacts on the decomposition rate constant. For different combinations of these characteristics the decomposition rate constant ranged from a minimum of 0.0165 per year to a maximum of 0.0488 per year.
Selection for height growth and Pilodyn pin penetration in lodgepole pine: effects on growth traits, wood properties, and their relationships
Authors: Wang Tongli , Aitken Sally N , Rozenberg Philippe , Carlson Michael R
Published: April 2011

The effects of selection using indices of height growth and wood density based on Pilodyn pin penetration (PIN) and the relationships among growth traits and wood properties were investigated in lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.). Four subpopulations were constructed by selecting 10 open-pollinated families in each of four categories: (i) fast height growth and high wood density, (ii) slow height growth and high density, (iii) fast height growth and low density, and (iv) slow height growth and low density. Eleven-year growth, PIN, and wood-density traits generated from X-ray densitometry were analyzed. We found that selection of subpopulations using indices of height and PIN resulted in significant differences among subpopulations in most growth and wood-density parameters. However, PIN underestimated the wood density of families with large diameter. Disk density was found to be moderately negatively correlated with diameter growth, weakly negatively correlated with stem volume, but not significantly correlated with height. Selection for latewood proportion to improve wood density in lodgepole pine is likely to result in a reduction in growth and biomass production; however, selection for total latewood volume or simply height has the potential to increase both growth and wood density.
Hexazinone dissipation in forest ecosystems and impacts on aquatic communities
Authors: Michael Jerry L , Webber, Jr. E Cliff , Bayne David R , Fischer Joseph B , Gibbs Hilliard L , Seesock Wendy C
Published: April 2011

Hexazinone (active ingredient) was aerially applied as a pellet (Velpar ULW) and as a liquid (Velpar L) to watersheds in the Piedmont of Alabama, U.S.A., at the rate of 6.72 kg·ha-1 (three times the prescribed rate for this site). An untreated watershed served as a control. We determined hexazinone half-life in days for Velpar ULW (plants, 26-59; litter, 55; bare soil, 68; soil under litter, 74) and for Velpar L (plants, 19-36; litter, 56; bare soil, 77; soil under litter, 275). Maximum stream concentrations of hexazinone (422 µg·L-1 for Velpar ULW; 473 µg·L-1 for Velpar L) were observed during application and resulted from direct overspray. Hexazinone stream concentrations peaked several times during stormflow in the first 30 days (56-70 µg·L-1 for Velpar ULW; 145-230 µg·L-1 for Velpar L) and were diluted three to five times 1.6 km downstream. Hexazinone metabolites were also monitored. Exposure of macroinvertebrates to hexazinone did not alter benthic community structure. Taxa richness, including pollution-sensitive insects, did not differ significantly between either hexazinone treatment and the control. Benthic macroinvertebrates in Piedmont streams of the southeastern United States appear insensitive to hexazinone at the exposures observed in this study.
Hemlock woolly adelgid impacts on community structure and N cycling rates in eastern hemlock forests
Authors: Jenkins Jennifer C , Aber John D , Canham Charles D
Published: April 2011

Mortality of dominant tree species caused by introduced pests and pathogens have been among the most pervasive and visible impacts of humans on eastern U.S. forests in the 20th century, yet little is known about the ecosystem-level consequences of these invasions. In this study we quantified the impacts of the introduced hemlock woolly adelgid (Adelges tsugae Annand) on community structure and ecosystem processes in eastern hemlock (Tsuga canadensis (L.) Carr.) forests in southern New England. Data were collected at six hemlock-dominated sites spanning a continuum from 0 to 99% mortality. Light availability to the understory and seedling regeneration both increased in stands affected by the adelgid. Differences in soil organic matter, total C, and total N pools between infested and noninfested sites were not associated with hemlock decline. Net N mineralization, nitrification, and N turnover increased at sites experiencing hemlock mortality. Inorganic N availability and nitrification rates increased dramatically with adelgid infestation and hemlock mortality, suggesting that nitrate leaching is likely in regions experiencing hemlock mortality. In the longer term, ecosystem processes at infested stands are likely to be driven by the successional dynamics that follow hemlock mortality.
Comparison of structural and compositional characteristics in old-growth and mature, managed hardwood forests of Minnesota, U.S.A.
Authors: Hale C M , Pastor J , Rusterholz K A
Published: April 2011

Extended rotation of managed temperate hardwood forests is sometimes presumed to provide the important compositional and structural features of old-growth hardwood forests. However, the features of temperate hardwood old-growth and managed stands of extended rotation age have not been fully quantified and compared. This study compared quantitative parameters (density and volume of logs and snags, coarse woody debris volume (volume of logs + volume of snags), the proportion of hollow logs, basal area and tree, sapling, large seedling and small seedling densities), distributional patterns (diameter class and rot class of live trees, decay class of logs), and vascular plant species composition and diversity in old-growth and mature, managed sugar maple (Acer saccharum L.) - basswood (Tilia americana L.) and northern red oak (Quercus rubra L.) stands. Old-growth forests had higher coarse woody debris volumes and higher proportions of hollow logs, of live trees in large diameter classes, of logs in decay classes 1 and 2, and of live trees in rot classes 3-5 than the mature, managed forests. Old-growth and mature, managed forests did not differ significantly in plant species composition. These results indicate that, while older extended-rotation, managed stands can be very similar compositionally to old-growth forests, they differ quantitatively in structural features.
Stand development in an old-growth subalpine forest in southern interior British Columbia
Authors: Parish R , Antos J A , Fortin M -J
Published: April 2011

The dynamics of an old-growth Engelmann spruce (Picea engelmannii Parry) - subalpine fir (Abies lasiocarpa (Hook.) Nutt.) forest were investigated using stand-history reconstruction. Age and size structures, tree location, and radial increment patterns were used to link establishment and growth to disturbances. The spatial distribution of trees was used to infer patterns of establishment and mortality. The forest originated in the 1650s, probably after fire. Initial establishment took almost 80 years, after which fir continued to recruit effectively, but spruce did not. The tree-ring record showed no evidence of widespread disturbance during the first 200 years, but from about 1855 to 1900 a major period of canopy mortality caused by bark beetles released suppressed trees and provided opportunities for establishment and rapid growth of seedlings of both species. Most current canopy trees established or released during this period of disturbance; thus, many canopy trees are fairly young in this old-growth forest and canopy turnover is high. A short period of disturbance (1927-1932) caused by the balsam bark beetle (Dryocoetes confusus Swaine) resulted in release of suppressed trees but did not promote seedling establishment. At the time of study (1994), the stand was undergoing another minor disturbance caused by this insect. Bark beetles appear to be of fundamental importance in controlling the dynamics of spruce-fir forests during the long intervals that often occur between fires in cool, wet climates.
Chondrostereum purpureum as a biological control agent in forest vegetation management. III. Infection survey of a national field trial
Authors: Becker Elisa M , Ball L Alex , Dumas Michael T , Pitt Doug G , Wall Ronald E , Hintz William E
Published: April 2011

A nationally coordinated field trial was established in the summer of 1995 to assess the utility of Chondrostereum purpureum (Pers. ex Fr.) Pouzar as a biocontrol agent for several weedy deciduous species. In this study, C. purpureum infection of cut stumps was surveyed 4 months following applications of the biocontrol agent in New Brunswick and Ontario field trials. The use of diagnostic molecular genetic markers to detect and identify C. purpureum was compared with morphological identification methods. Samples of trembling aspen (Populus tremuloides Michx.) and red maple (Acer rubrum L.) from the New Brunswick trials confirmed infection with the biocontrol isolates of C. purpureum, and no cross contamination of treatment applications was detected. Analyses of recovered fungal samples from aspen and speckled alder (Alnus rugosa (Du Roi) Spreng.) in Ontario also confirmed the success of biocontrol infection. The percentage of C. purpureum infected stumps differed between hosts in the Ontario trials. An average of 84% of speckled alder stems and 54% of aspen stems were estimated to have been infected by the applied isolates of C. purpureum. Given a sufficient number of samples, this methodology can provide an early indication of successful stump infection by C. purpureum, a prerequisite for effective weed biocontrol.
Poplar nutrient resorption in fall or drought: influence of nutrient status and clone
Authors: Harvey H P , van den Driessche R
Published: April 2011

Nutrient mobilization in hybrid poplars was studied in two greenhouse experiments. Half the clones in each experiment were drought resistant and half were drought sensitive. In experiment 1, four clones were grown at three levels of N, two levels of P, and with four drought treatments. In experiment 2, six clones received two levels of N and three levels of K. Well-watered trees, trees subjected to drought conditions once, and hardened drought-stressed trees were harvested in late summer, and other well-watered trees were harvested in fall. Mobilization of nutrients differed with speed and intensity of drought. During gradual drought in the first experiment, N and P were resorbed but not K or Cu. In experiment 2, drought was too rapid for resorption. Instead, nutrients became more concentrated: increased N facilitated hardening and osmotic adjustment, while K moved out of the leaves on rewatering. In fall, N, P, Cu, and K were resorbed. Increased K supply increased fall resorption efficiency of Cu, N, and P but not K. Increased N supply improved fall resorption proficiency of K at low levels of supply. However, clonal productivity on dry sites was more related to leaf retention in drought and in fall than to resorption efficiency.
How much primary coastal temperate rain forest should society retain? Carbon uptake, recreation, and other values
Authors: van Kooten G Cornelis , Bulte Erwin H
Published: April 2011

In this study, average and marginal approaches for determining optimal preservation of primary forests on British Columbia's coast are compared. When the market values from timber, mushrooms, etc., and nonmarket benefits (e.g., carbon sink, preservation values) of preserving old-growth forests are considered (where the opportunity cost of preserving such forests are the benefits of commercial forestry foregone), the average method recommends harvest of all remaining old growth. For the marginal approach, a deterministic optimal control model is solved to compute socially optimal stocks of old growth. In this case, the numerical results indicate that large-scale conversion of old-growth forests cannot be justified on economic grounds.
A 370-year dendroecological history of an old-growth Abies-Acer-Quercus forest in Hokkaido, northern Japan
Authors: Abrams Marc D , Copenheaver Carolyn A , Terazawa Kazuhiko , Umeki Kiyoshi , Takiya Mika , Akashi Nobuhiro
Published: April 2011

Dendroecological techniques were used to study the dynamics and species recruitment patterns, spanning nearly four centuries, for a mesic, montane, old-growth forest in Hokkaido, northern Japan. The forest is dominated by Abies sachalinensis (Masters), Acer palmatum (Thunb.),Quercus mongolica var. grosseserrata (Rehd.), and Cercidiphyllum japonicum (Sieb.). From 1620 to 1750 and 1820 to 1840, Q. mongolica exhibited continuous recruitment into the overstory. A lack of recruitment for all tree species from 1750 to 1820 followed a 1739 volcanic eruption 200 km from the study area. Release events for individual trees occurred almost every decade of the stand history, indicating that frequent small-scale disturbances coupled with infrequent large-scale disturbances, impact tree growth and species recruitment. From 1870 to 1950, canopy recruitment of Abies and Acer dominated the forest, while recruitment of Quercus ceased. These later successional species appeared to be replacing Quercus, suggesting that the syndrome of declining oak dominance is an increasingly global phenomenon. However, successional patterns in the forest are difficult to predict because intensive deer browsing has recently prevented canopy recruitment of all tree species and the possibility of future large-scale disturbances, such as fire and volcanic eruption.
Incomplete block designs for genetic testing: some practical considerations
Authors: Fu Yong-Bi , Yanchuk Alvin D , Namkoong Gene
Published: April 2011

Full-sib progeny and clonal trials to evaluate family and clone performance were simulated on a test site with various patterns of environmental variation to examine the effectiveness of randomized incomplete block designs (ICBs) under different design parameters (constant block size, variable block size, block shape and orientation, and family size). Simulations showed that blocks of fixed size 5-20 were effective in removing most site variation in a test with 120 full-sib families of three seedlings per family. Slight variations in block size did not affect the precision of mean estimations much when blocks were considered random. Square blocks were more effective than either column or row blocks in removing both patchy variation and gradients in one direction. With blocks of fixed size 10, increasing family size from 3 to 12 (at the expense of family number, which dropped from 120 to 30) reduced the average variance of family mean contrasts by 75%; most of this reduction (>50%) was achieved at 6 seedlings per family. The differences in precision of mean estimation between full-sib progeny and clonal trials were small with respect to the design parameters and patterns of site variation examined.
Guidelines for choosing volume equations in the presence of measurement error in height
Authors: Williams M S , Schreuder H T
Published: April 2011

Assuming volume equations with multiplicative errors, we derive simple conditions for determining when measurement error in total height is large enough that only using tree diameter, rather than both diameter and height, is more reliable for predicting tree volumes. Based on data for different tree species of excurrent form, we conclude that measurement errors up to ±40% of the true height can be tolerated before inclusion of estimated height in volume prediction is no longer warranted.
Predicted impacts of hard pine stem rusts on lodgepole pine dominated stands in central British Columbia
Authors: Woods Alex J , Nussbaum Albert , Golding Bill
Published: April 2011

We developed two models to predict volume loss due to western gall rust (Endocronartium harknessii (J.P. Moore) Y. Hiratsuka) and comandra blister rust (Cronartium comandrae Peck) on juvenile lodgepole pine (Pinus contorta Dougl. ex Loud.) dominated stands in central British Columbia. The models suggest that volume loss is significantly and positively correlated to the incidence of comandra blister rust. The relationship between volume loss and western gall rust incidence was weak. The addition of stand density data improved the statistical fit of the model. We used the growth and yield model Tree and stand simulator (TASS) to predict volume at culmination age (age at which the merchantable mean annual increment was maximized) in thirty 1-ha stem-mapped stands. The lodgepole pine trees we stem mapped were also assessed for hard pine stem rust incidence. We developed our volume loss functions assuming that trees with stem infections of both comandra blister rust and western gall rust were lethal, and that infected trees would die from ages 21 to 40. In areas where comandra blister rust is common, the losses due to the disease can be considerable. We predict that the volume losses due to hard pine stem rusts in lodgepole pine dominated stands are as high as 7.2% by culmination age.
Influence of nitrate and other anions on fast and slow contractions of crab muscle
Authors: Atwood H. L.
Published: April 2011

The effects of bromide, nitrate, iodide, and thiocyanate ions on the neurally evoked fast and slow contractions of a crab muscle were investigated. Both types of contraction were depressed in bromide and nitrate. In iodide and thiocyanate, the slow contraction was often depressed but the fast contraction was potentiated. The foreign anions increased muscle fiber membrane resistance and the amplitudes of both fast and slow postsynaptic potentials. Records of tension development in single muscle fibers showed that more stimulating current was required to produce a given tension in nitrate than in the standard bathing fluid; this change was related to hyperpolarization of the muscle fiber membrane in nitrate. Potassium contractures also were inhibited by nitrate, because of the less effective depolarization of the cell membrane by potassium ion in the presence of nitrate. No marked shift in the membrane potential threshold for contraction occurred after treatment with the foreign anions.
Effects of cooling and rewarming on Na, K, and tension changes in rat tail artery
Authors: Friedman Sydney M. , Nakashima Miyoshi , Friedman Constance L.
Published: April 2011

The relation of cell Na and K to vascular smooth muscle tension was studied in the isolated, perfused rat tail artery. Glass electrodes were used to measure ion exchanges; cooling and rewarming were used to modify cell ion content and exchange rates. The cells, made Na-rich and K-poor by overnight cooling of the artery at 2 °C, responded weakly to vasoactive agents (norepinephrine, L-8 vasopressin, and angiotensin) and characteristically showed a slow rate of rise followed by a still slower rate of fall in tension. Within minutes of initiating rewarming to 37 °C the rate of rise was accelerated even in the presence of metabolic inhibitors. The degree of rise depended on the degree of restoration of ionic gradients; it increased progressively with the time allowed for extrusion of Na and reaccumulation of K, a process which could be blocked by iodoacetate. During rewarming, the Na/K exchange rate rose from zero at 2 °C to reach a maximum toward the end of the first hour of rewarming, and in this interval the rate of relaxation following stimulation returned to normal. Stimulation of the cold artery with angiotensin enhanced subsequent Na outflow during rewarming without affecting K inflow, and the tissue was unable to respond to a second stimulus.
Effect of Isomers of DDD on thyroid and adrenal function in rats
Authors: Fregly M. J. , Waters I. W. , Straw J. A.
Published: April 2011

Dietary administration of o,p′-DDD (2,2-bis(2-chlorophenyl, 4-chlorophenyl)-1,1-dichloroethane) at 1.0 and 3.0 g/kg food for 6 weeks increased the thyroid weight of male albino rats by 62 and 81% respectively. The rate of oxygen consumption (measured at 30 °C) and gain in body weight were unaffected by treatment. The rate of loss of 131I from the thyroid gland was significantly faster for both treated groups than for controls. These results suggest that the chronic administration of o,p′-DDD at the doses used resulted in a compensated hypothyroidism in rats. In another experiment, the thyroid weight of female hooded rats given m,p′-DDD (1.0 g/kg food) and p,p′-DDD (1.0 and 3.0 g/kg food) for 24 weeks also increased 112, 94, and 113% respectively above control weight. Ninety-six hours after the administration of thyroxine-131I, significantly greater fecal and less urinary excretion of radioactivity was observed for all treated groups than for the control group. The increase in thyroid weight of the treated rats may be associated with increased hepatic metabolism of thyroxine, but specific effects on the thyroid gland have not been excluded. Although isomers of DDD are reported to induce atrophy of the adrenal cortex and to reduce glucocorticoid secretion in dogs, no effect of the chronic administration of isomers of DDD on adrenal weight or production of either total Δ4-3 ketosteroids or corticosterone in vitro was observed in the case of rats. The rate of metabolism of desoxycorticosterone in vitro by rat liver slices was also unaffected by chronic treatment with o,p′-DDD.
Inhibition of eledoisin by morin on the isolated guinea pig ileum
Authors: Gascon André L.
Published: April 2011

The response of the isolated guinea pig ileum to angiotensin, bradykinin, eledoisin, and acetylcholine was studied before and during exposure to morin. Dose–response curves were made for each agonist in the presence of different concentrations of the flavonoid (1 to 8 μg/ml). Under these conditions, the responses of the ileum to eledoisin, angiotensin, and acetylcholine were modified to various degrees depending upon the concentration of morin. With morin 1 μg/ml, the effect of eledoisin was reduced, and the activity of this polypeptide progressively decreased with an increase in the concentration of the inhibitor. On the other hand, the activity of acetylcholine was potentiated while that of bradykinin and angiotensin was unchanged. With higher concentrations of morin (4 and 8 μg/ml), the effect of both angiotensin and acetylcholine was slightly reduced. On the rat blood pressure, morin did not modify the effect of agonists. From these results it is concluded that morin is a specific and noncompetitive inhibitor of eledoisin on the isolated guinea pig ileum.
Effect of chlorophenoxyisobutyrate on rat liver non-saponifiables
Authors: Phillips W. E. J. , Lakshmanan M. R. , Brien R. L.
Published: April 2011

Chlorophenoxyisobutyrate (CPIB) when fed in the diet at 0.2% for periods of from 3 to 25 days increased liver weight by 28% and increased total liver ubiquinones by 75%. This increase did not change succinate-neotetrazolium reductase activity. Although serum cholesterol levels were significantly reduced, no changes were observed in total liver cholesterol or vitamin A. The data suggest that this hypocholesterolemic agent, although it increases ubiquinone, does not adversely affect the above enzyme activity nor does it modify vitamin A utilization as determined from liver stores.
A free fatty acid – free thyroxine relationship in serum
Authors: Radomski M. W. , Britton A. , Schönbaum E.
Published: April 2011

Serum free fatty acid (FFA) and free thyroxine (T4) levels were measured in six healthy Army volunteers after exercise, and in rats fasted for 24 and 48 h or exposed to 4 °C for 3 and 6 h. A close relationship between FFA and free T4 values was found in humans and rats. It is suggested that this phenomenon may be a displacement of bound T4 from its binding sites by FFA resulting in short-term changes in metabolically available T4.
Convulsions and the γ-aminobutyric acid content of rat brain
Authors: DeFeudis F. V. , Elliott K. A. C.
Published: April 2011

The observation of Wood and Watson that the γ-aminobutyric acid content of the brain decreases in animals that suffer convulsions during treatment with oxygen at high pressure has been confirmed. This decrease is prevented when seizures are prevented by prior intraperitoneal injections of hyperosmotic solutions. When seizures are induced by picrotoxin or pentylenetetrazol the GABA levels are slightly (and alanine levels considerably) increased.
A study of newborn rats exposed to the cold
Authors: Thompson G. E. , Moore R. E.
Published: April 2011

The purpose of this investigation was to study heat production in the newborn rat, and the factors which may be limiting maximum heat production in the cold. Rats of varying ages between 1 and 30 days were exposed to various environmental temperatures. The minimum oxygen consumption in the warm, and maximum oxygen consumption in the cold, increased with age. The critical environmental temperature, and the environmental temperature at which oxygen consumption was maximal, fell with increase in age. Exogenous noradrenaline raised the oxygen consumption of 6-day-old but not of 12-day-old rats above the maximum oxygen consumption found with cold exposure. The cardiac output and arteriovenous oxygen difference of 12-day-old rats was increased in the cold. These results are consistent with the view that oxygen consumption in the cold is limited in 6-day-old rats by the release of endogenous noradrenaline and in 12-day-old rats by cardiac output and the supply of oxygen to the heat-producing tissues.
A method for production of experimental hypertension in rats
Authors: Rojo-Ortega J. M. , Genest J.
Published: April 2011

A new and simple procedure for producing experimental hypertension in rats is described. It consists in the complete ligature of the aorta between the origin of the renal arteries. Production of an atrophic left kidney depends closely on the rat's body weight, occurring in about 90% of rats weighing over 300 g and almost never in those weighing under 150 g. The great majority of rats weighing more than 300 g with atrophic left kidneys were hypertensive.
Spontaneous activity of sympathetic preganglionic neurons
Authors: Polosa Canio
Published: April 2011

Electrical activity of sympathetic preganglionic neurons in the upper thoracic cord of anesthetized cats was recorded with extracellular microelectrodes. The neurons were identified by their antidromic response to stimulation of the ipsilateral sympathetic cervical nerve. Of a total of 210 units observed, only 44 (21%) were spontaneously active. The discharge pattern was "regular" in 7%, "bursty" in 15%, and "irregular" in 78% of the units. The mean discharge rate was 1.4 spikes/s (range 0.1–5.6) and in any one cell changed little with time. Most spike trains showed a lack of short (i.e. less than 100 ms) interspike intervals. Interpolation of an antidromic impulse in the "regular" spike trains caused a resetting of the rhythm, thus suggesting that the rhythm is endogenous to the sympathetic preganglionic neuron itself. Spontaneous activity was observed in a decentralized, deafferented segment of spinal cord, thus suggesting that the activity can be autochthonous. Injection of a pressor drug resulted in a transient depression of the rate of spontaneous firing. Hemorrhage caused a transient increase of the rate of firing in some units, in others a transient decrease or complete arrest.
Effect of adrenaline and propranolol on the superior mesenteric artery blood flow
Authors: Greenway C. V. , Lawson Anne E.
Published: April 2011

Adrenaline infusions into the superior mesenteric artery caused a marked increase in superior mesenteric artery blood flow with little change in arterial pressure. This vasodilation was blocked after the intravenous administration of propranolol.
Studies with fluorescein-conjugated antisera to growth hormones: II. Inhibition studies in the pituitary in various species
Authors: Nayak R. , McGarry Eleanor E. , Beck J. C.
Published: April 2011

Multiple antigenic sites on growth hormone were determined by the fluorescent-antibody method, with use of heterologous antigen and antisera for inhibition.
Two sympathetic nerve supplies to brown adipose tissue of the rat
Authors: Derry D. M. , Schönbaum E. , Steiner G.
Published: April 2011

The fluorescent histochemical technique of Falck for demonstrating catecholamines in sympathetic nerve fibers was modified for use in brown fat. In normal interscapular and mediastinal brown fat, the nerve fibers surrounded the arterial Mood vessels and all parenchymal cells. Both immunosympathectomy and surgical denervation gave an almost identical histological picture of massive loss of nerves from the blood vessels only. The parenchymal innervation remained intact. The blood vessels retained single isolated nerve fibers, which were relatively more numerous on the small vessels and which were connected with the parenchymal innervation. After sympathetic nerve fibers were depleted of catecholamines by treating the rat with reserpine, the parenchymal nerves reestablished catecholamine fluorescence at a faster rate than the blood vessel nerves. Intrinsic (tissue) ganglia in the brown fat were resistant to immunosympathectomy. These ganglia contained cells which were very brightly fluorescent. These results indicate that there are two anatomically, immunologically, and pharmacologically different nerve supplies to brown fat, one to the blood vessels and the other predominantly to the parenchyma. It was concluded that the parenchymal nerve supply is derived from the intrinsic ganglia via 'short' adrenergic neurons, and the blood vessel innervation is derived from the sympathetic chain via 'long' adrenergic neurons.
Effects of propranolol on the resting and exercise hemodynamics of pulmonary stenosis
Authors: Cumming Gordon R. , Mir G. H.
Published: April 2011

Propranolol 0.016 mg/kg was given to 15 patients with pulmonary stenosis to study the effects of beta adrenergic inhibition on right ventricular (RV) dynamics at rest and during exercise. After propranolol, mean heart rate declined 8 beats/min at rest and 21 beats/min during exercise; mean cardiac index decreased 0.6 l/min at rest, 1.0 l/min during exercise; stroke index decreased 4.0 ml at rest, was unchanged during exercise; mean peak systolic RV pressure fell 8 mm at rest, 24 mm during exercise; RV end-diastolic pressure increased 3 mm during exercise; brachial artery systolic pressure decreased 24 mm during exercise; the duration of RV systole during exercise was increased by 0.03 s; mean RV pressures decreased 5 mm at rest, 11 mm during exercise; RV tension time index decreased 20% at rest, 26% during exercise; and mean mixed venous oxygen saturation during exercise fell from 42 to 35%. This study serves to emphasize that peak RV pressures in pulmonary stenosis are not only dependent on valvular anatomy and stroke volume, but also on the rate and pattern of ventricular ejection.
Observations on an anorexigenic material isolated from urine
Authors: Beaton J. R. , Uehara P. S.
Published: April 2011

An anorexigenic material isolated from rat urine (FMS IA) was investigated. Ultrafiltration and sieving through polyacrylamide gel indicated a molecular weight in excess of 50 000. Anorexigenic activity was not destroyed by heating to 37 °C for 6 h or to 100 °C for 10 min, or by digestion with pepsin for 2 h. Digestion with trypsin yielded an active fraction with molecular weight < 10 000. Extraction of this digest with ether did not eliminate the activity nor did the ether extract possess anorexigenic activity per se. Qualitative tests of the ether extract were negative for steroid-like material. These and prior results suggest the anorexigenic factor may be a polypeptide bound to a larger protein. In normal and hypothalamicobese rats, the amount excreted in urine was greater under fed than under fasting conditions. The obese rats were more responsive to the anorexigenic material than were normal rats. It is suggested that the anorexigenic factor may play a role in the regulation of food intake.
Temperature and experimental acute cardiac necrosis
Authors: Faltová E. , Poupa O.
Published: April 2011

The effect of an increased ambient temperature on the incidence of acute myocardial necrosis caused by two subcutaneous injections of isoproterenol (80 mg/kg) 24 h apart has been investigated. Raising the temperature of the microclimate in the cages by 3–5 °C considerably increased the incidence of cardiac necrosis and the mortality after isoproterenol. Increasing the number of animals per cage enhanced the necrogenic effect of isoproterenol on heart muscle due to a rise in cage temperature. Exposing rats for 3–4 h after isoproterenol administration to a raised ambient temperature increased their sensitivity to isoproterenol. The same exposure made 20 h after isoproterenol administration had no such effect. Shaving the animals decreased their sensitivity to isoproterenol at an increased ambient temperature. The relation between the necrogenic effect of catecholamines and thermoregulation is discussed.
The survival of DF32P-labelled erythrocytes in molybdate-fed rabbits
Authors: Robinson G. A. , Valli V. E. O. , McSherry B. J. , Pepino Anne McCarter
Published: April 2011

The life-span of erythrocytes labelled in vivo with diisopropyl phosphorofluoridate-32P (DF32P) was studied in rabbits fed toxic quantities of sodium molybdate. Mean erythrocyte survival times were 57.0 ± 2.4 (S.E.M., N = 14) for control rabbits and 58.8 ± 1.6 (S.E.M., N = 20) for test rabbits fed a commercial pelleted diet, and 45.8 ± 1.8 (S.E.M., N = 15) for control rabbits and 27.8 ± 2.1 (S.E.M., N = 12) for test rabbits fed an oats–alfalfa based diet. Oats–alfalfa fed test rabbits developed severe anemia after 2 to 5 weeks on the toxic diet whereas pellet-fed test rabbits did not. These findings indicated that the anemia which developed in oats–alfalfa–molybdate fed rabbits resulted from a shortened erythrocyte survival time as well as from the reduced rate of erythrocyte maturation reported previously.
Influence of aortic coarctation on myocardial glucose-6-phosphate dehydrogenase
Authors: Valadares J. R. E. , Singhal R. L. , Parulekar M. R. , Beznak Margaret
Published: April 2011

Alterations in the activity of myocardial glucose-6-phosphate dehydrogenase were studied in rats with experimentally produced cardiac hypertrophy. Six days after aortic coarctation, enzyme activity was increased to more than 200% of the control values when expressed either per gram wet weight or per organ. Administration of cycloheximide resulted in a significant inhibition of the increase in cardiac glucose-6-phosphate dehydrogenase noted after constriction. It is conceivable that the augmentation in the activity of this enzyme may be related to the increases in RNA and protein synthesis observed during development of cardiac hypertrophy.
Effect of long-term treatment with an anticholinergic drug on parietal cell mass in rats
Authors: Kowalewski K.
Published: April 2011

An anticholinergic drug, propantheline bromide, was given to rats in a dosage of 5 mg/kg body weight twice daily, for 6, 9, or 12 months. Parietal cell mass was determined in these animals and in controls of similar age and weight. A significant decrease in the number of parietal cells was found in the stomachs of treated rats. This was considered to represent an "inhibition hypoplasia" produced experimentally.
Effects of reserpine on cardiac calcification in DBA mice
Authors: Smith-Vaniz George T. , Glower Ben R. , Matheny J. L.
Published: April 2011

The effect of daily injections of 0.1 mg/kg reserpine (Serpasil) on pathologic calcification of cardiac tissue in 12- to 16-month-old DBA strain mice was studied. After 3 weeks of daily injections, the tissue calcium levels were decreased significantly from control levels of 18.6 (atrial) to 13.2 and 20.1 (ventricular) to 12.8 meq Ca++/kg fat-free dry weight respectively. Histological observations also showed a decrease in spontaneous calcification of cardiac tissue in the reserpinized mice. Frequent findings in the calcified areas of the reserpine-treated mice were: less extensive calcification, a more granular appearance of the mineral, an associated inflammatory reaction, and adjacent areas of myocardial necrosis.
Effect of growth hormone and thyroxine on isometric contractile mechanics of cardiac muscle
Authors: Minelli R. , Korecky B.
Published: April 2011

To classify the effects of hormonal interventions on myocardial contractility the descriptive mechanics of contraction of isolated ventricular papillary muscles of rats were investigated under isometric conditions at 27 °C. The maximum developed tension (MT), the maximum rate of tension development (dT/dt), the mean rate of tension development (ΔT/Δt), and time to maximum tension (TMT) were determined in "rested-state contractions". Two strains of animals were used (Wistar and Sprague–Dawley). In each case the animals were divided into four groups: (1) normal, (2) hypophysectomized (Hx), (3) hypophysectomized and subsequently treated with growth hormone (GH), and (4) hypophysectomized and subsequently treated with thyroxine (T4). MT decreased after hypophysectomy, was not changed after GH administration, and was improved after T4 administration. The decrease of MT in groups 2 and 3 was due to a decrease in dT/dt and ΔT/Δt and was partly compensated by prolonged TMT. Administration of T4 brought the values of dT/dt and ΔT/Δt to normal, and shortened the value of TMT below normal. These experiments indicate that although the decrease in MT after hypophysectomy was relatively small the pattern of the descriptive mechanics of contraction was profoundly altered. The results suggest that the degree of activation may have been decreased and that the contraction became slower and lasted longer. These changes were not influenced by GH but were reversed by T4 administration.
Peripheral pathways and properties of uterine afferents in the cat
Authors: Abrahams V. C. , Teare J. L.
Published: April 2011

Recordings were made from pelvic, hypogastric, and uterine nerves of the nonpregnant cat during electrical stimulation, manual compression, and inflation of the uterus and vagina. Unit recording showed that most but not all afferents from the uterus and vagina travel in the hypogastric, where they may constitute about 5% of the afferent fibers. Receptors were both restricted field and wide field, and although readily excited by manual compression they were less readily excited by increased intrauterine pressure.
Diminished thyroidal activity in chicks in response to lysine deficiency
Authors: Pastro K. R. , March B. E. , Biely J.
Published: April 2011

Iodine-131 was injected into chicks either 1 day after, or 3 days before, imposing the dietary treatments. The rates of thyroidal uptake and (or) release of iodine-131 were used to assess thyroidal activity. Within 1 day of feeding a lysine-deficient diet, thyroidal activity declined.
The recalcification plasma clotting time. A valuable general clotting test in man and rats
Authors: Renaud Serge
Published: April 2011

An improved method for determining the recalcification plasma clotting time (PCT) in siliconized and plastic material is described. Provided the plasma is stored at 29–30 °C, this general clotting test appears to give highly accurate and reproducible results. The PCT values were found to be related to the in vivo platelet count in rat, and to the total serum cholesterol and plasma fibrinogen in man. Serial determinations in two women indicated that the PCT was subject to periodic fluctuations connected with the menstrual cycle. Finally, it was observed that the clotting time of both platelet-rich and -poor plasma was inversely related to the severity of large hepatic vein thrombosis initiated by the injection of a S. typhosa endotoxin in hyperlipemic rats.
The nature of Wenckebach cycles
Authors: Roberge F. A. , Nadeau R. A.
Published: April 2011

Various patterns of unstable second-degree AV block were observed in the dog following selective injection of acetylstrophanthidin into the AV node artery. Analysis of the changes in RR and PR intervals during slow transitions between 1:1 rhythm and 2:1 block showed that well-organized sequences of periodic arrhythmias occurred during these transitions, thus verifying a previous hypothesis made on the basis of model experiments. Wenckebach cycles of variable duration are seen near 1:1 rhythm, whereas cyclic patterns of partial 2:1 block (also called "reverse Wenckebach" cycles) appear near 2:1 block; these two modes are separated by 3:2 block characterized by alternation between long and short ventricular intervals. The close correspondence between experimental observations and the results of a simulation study with a relaxation-oscillator model of the AV junction raises the possibility that these periodic arrhythmias may be explained solely in terms of the properties of threshold and refractoriness of the AV junction.
Fate of vasopressin and oxytocin in the pulmonary circulation
Authors: Biron P. , Boileau J.-C.
Published: April 2011

The pulmonary inactivation of lys-8 vasopressin in anesthetized, normal dogs, cats, rabbits, and rats, and that of Pitressin in rats, was studied by means of the systemic pressure response technique. The pulmonary fate of oxytocin was measured in rats by the same technique and, in addition, by means of an in vivo oxytocic assay. The pulmonary inactivation of these three neurohypophyseal peptides was negligible in all instances. The data reinforce the concept that circulating hormones freely cross the pulmonary vascular bed.
Analysis of the central vasomotor effects of (−)-N-(1-phenylethyl)guanidine, a new adrenergic neuron blocking agent
Authors: Bapat S. K. , Dhawan B. N. , Srimal R. C.
Published: April 2011

Central vasomotor effects of (−)-N-(1-phenylethyl)guanidine, a potent adrenergic neuron blocking agent, were studied. The compound was localized in the central sites by intracerebroventricular injection, topical application on the vasomotor center, intra-arterial (vertebral) injection, and intrathecal injection. It potentiated the carotid occlusion response, response to anoxia, spinal compression vasomotor response, and the threshold and optimal vasomotor responses to direct electrical stimulation of the medullary vasomotor center without affecting the peripheral norepinephrine pressor response and the nictitating membrane response. The peak effect was obtained in 15–20 min, and recovery occurred in 80–90 min. The compound probably made catecholamines unavailable to the vasomotor neurons, making them more excitable.
The effect of temperature on the responses to electrical stimulation of the isolated cerebral cortex of the cat
Authors: Harwood J. P. , Sanders H. D.
Published: April 2011

The effect of temperature over the range 28 to 37 °C was studied on the electrically induced responses in the neuronally isolated cortex of the cat. The positive burst response (PBR) was found to be insensitive to a fall in temperature with no change in threshold, although the duration of the response was increased at low temperature. The threshold for inducing the epileptiform afterdischarge (EAD) remained constant in some animals but decreased in half of the animals studied. As the temperature was lowered, the amplitude of the EAD decreased while the frequency increased. The epileptiform sustaining response (ESR) on the other hand was markedly sensitive to temperature and disappeared around 32 °C. The differential effect of temperature upon the PBR and ESR, which have similar parameters for their production, provides further evidence for the separate identity of the two responses.
The effects of various pharmacological agents on the distribution of antihistamine activity of rat tissue extracts
Authors: Lefcort M. , Francis L. E. , Melville K. I.
Published: April 2011

Extracts of rat tissues (ear and abdominal skin, heart, cerebrum, spleen, kidney, lung, liver, stomach, and jejunum) were tested for their ability to antagonize histamine on the guinea pig ileum preparation. Antihistamine activity varied considerably between tissues; it was found to be highest in the ear skin and lowest in the jejunum and stomach. After pretreatment with semicarbazide (plus a pyridoxine-free diet) or reserpine, or after adrenalectomy, the antihistamine activity was reduced in some tissues but was increased in others. The variation in the behavior of the different tissues with these treatments made it impossible to interpret the distribution of antihistamine activity in terms of known sites of amine formation. After treatment with compound 48/80, however, there was an apparent parallelism between loss of antihistamine activity and depletion of mast cell histamine.