bluuebunny/crossref_metadata_2025 huggingface dataset:
Boreal forest ecosystem dynamics. I. A new spatial model
Authors: Yarie John
Published: April 2011

Modeling the biology of forest ecosystems has been devoted to a combination of theoretical and empirical approaches representing the function of a forest ecosystem generally within an undefined spatial context. Moving to a large spatial context will require the use of theoretical representations of critical ecosystem functions that can be represented on an individual cell basis. A Spatial Alaskan Forest Ecosystem Dynamics (SAFED) model was developed that is based on the nitrogen productivity concept for forest growth, litter fall quality, and microbial efficiency for forest floor decomposition. Climate and ecosystem disturbances were handled as restricted stochastic processes. The restriction was based on known state-factor relationships. The state factors are used to describe a broad-scale classification of the landscape to define basic limitations for the randomly derived driving variables used in the model. The model has been programed as ARC/INFO macro language within the GRID package. The current version of the model has been verified as functional from an individual tree basis (1-m2 cell size) within an old-growth white spruce (Picea glauca (Moench) Voss) forest found in interior Alaska.
Co-baiting for spruce beetles, Dendroctonus rufipennis, and western balsam bark beetles, Dryocoetes confusus (Coleoptera: Scolytidae)
Authors: Greenwood Matthew E , Borden John H
Published: April 2011

Co-baiting to contain and concentrate the spruce beetle, Dendroctonus rufipennis (Kirby), and the western balsam bark beetle, Dryocoetes confusus Swaine, was investigated at four locations in British Columbia. Two 9-ha areas were established at each location; one was baited and the other left as a control. Single "interior firs," Abies bifolia A. Murray × Abies lasiocarpa (Hook.) Nutt., or groups of two or three trees, were baited with (±)-exo-brevicomin released at 1.0 mg/24 h. "Interior spruces," Picea engelmannii Engelm. ex Parry × Picea glauca (Moench) Voss, were baited with frontalin released at 0.1, 0.6, or 2.5 mg/24 h, or at 0.6 mg/24 h with alpha-pinene, ethanol, or ethyl crotonate. Another experiment investigated possible interspecific interference between D. confusus and D. rufipennis baits. Ratios of currently attacked "green" trees to previously attacked "red" trees for both insects were significantly higher in baited than in control areas, indicating that populations were contained. Baiting, however, did not attract either insect from a zone surrounding each baited area. There was a significant increase in D. confusus attack when two trees instead of one were baited per centre, no increase in D. rufipennis attack when frontalin was released alone or with the potential adjuvants, no effect of frontalin release rates on the percentage of trees attacked by D. rufipennis, and no indication of cross-repellency between baits.
Canopy openness and leaf area in chronosequences of coastal temperate rainforests
Authors: Frazer Gordon W , Trofymow J A , Lertzman Kenneth P
Published: April 2011

We examined spatial and temporal differences in canopy openness and effective leaf area (Le) in a series of eight forest chronosequences located on southern Vancouver Island, British Columbia. Structural attributes were measured on the west and east side of the island in immature, mature, and old-growth stands using hemispherical photography and the LAI-2000 plant canopy analyzer (PCA). Old-growth forest canopies were distinct from those of younger stands: they were more open, more heterogeneous in their openness, and maintained a lower stand Le. Although the overall developmental trajectories of forests were similar across the study sites, site-to-site differences in the rate and magnitude of these temporal changes indicated that site-specific factors also play a significant role in determining the character of forest canopies and their development. The most significant changes in canopy structure did not emerge until the later stages of stand development (150-200 years). Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) dominated east-side forests were, on average, more open, more heterogeneous, and had a lower stand Le than the stands dominated by western hemlock (Tsuga heterophylla (Raf.) Sarg.) and western redcedar (Thuja plicata Donn.) forming the west-side chronosequences. Shoot clumping, along with other evidence, suggested that species-related differences in leaf display and the geometry of branching structure might have contributed significantly to these regional patterns.
Leaf- and plant-level carbon gain in yellow birch, sugar maple, and beech seedlings from contrasting forest light environments
Authors: Beaudet Marilou , Messier Christian , Hilbert David W , Lo Ernest , Wang Zhang M , Lechowicz Martin J
Published: April 2011

Leaf-level photosynthetic-light response and plant-level daily carbon gain were estimated for seedlings of moderately shade-tolerant yellow birch (Betula alleghaniensis Britton) and shade-tolerant sugar maple (Acer saccharum Marsh.) and beech (Fagus grandifolia Ehrh.) growing in gaps and under a closed canopy in a sugar maple stand at Duchesnay, Que. All three species had a higher photosynthetic capacity (Amax) in the gaps than in shade, but yellow birch and beech responded more markedly than sugar maple to the increase in light availability. The high degree of plasticity observed in beech suggests that the prediction that photosynthetic plasticity should decrease with increasing shade tolerance may not hold when comparisons are made among a few late-successional species. Unit-area daily carbon gain (CA) was significantly higher in the gaps than in shade for all three species, but no significant difference was observed between light environments for plant-level carbon gain (CW). In shade, we found no difference of CA and CW among species. In gaps, beech had a significantly higher CA than sugar maple but similar to that of birch, and birch had a significantly higher CW than maple but similar to that of beech. Sugar maple consistently had lower carbon gains than yellow birch and beech but is nevertheless the dominant species at our study site. These results indicate that although plant-level carbon gain is presumably more closely related to growth and survival of a species than leaf-level photosynthesis, it is still many steps removed from the ecological success of a species.
Effect of Laccaria bicolor strains inoculated on Douglas-fir (Pseudotsuga menziesii) several years after nursery inoculation
Authors: Selosse M -A , Bouchard D , Martin F , Tacon F Le
Published: April 2011

In the Saint-Brisson experiment conducted in central France, the American strain of the ectomycorrhizal fungus Laccaria bicolor (Maire) P.D. Orton S238N and the French strain L. bicolor 81306 inoculated on containerized Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings increased by 60% the total volume of wood produced 8 years after outplanting as compared with uninoculated but naturally mycorrhizal trees. The two strains introduced 10 years before in the inoculated plots are still present and dominant; they did not prevent the colonization of Douglas-fir roots by naturally occurring ectomycorrhizal fungi but allowed for the establishment of a very diversified symbiotic microflora. Eight to 12 years after outplanting, all the Douglas-fir plots were colonized by Laccaria laccata (Scop.:Fr.) Cooke or L. bicolor strains, as well as some other species, independently of the nursery treatments. With one exception in one plot, the presence of indigenous genets in the control treatments may have prevented the vegetative colonization of the inside of the noninoculated plots by the two introduced strains.
Fibre properties of Norway spruce of different growth rates grown under birch shelterwoods of two densities
Authors: Bergqvist Göran , Bergsten Urban , Ahlqvist Bo
Published: April 2011

The effects of birch shelterwood density (0, 300, and 600 trees/ha) and growth rate on fibre and pulp properties of Norway spruce (Picea abies (L.) Karst.) understorey (growing at 1500 trees/ha) were evaluated for a trial in the boreal coniferous forest, 58 years after establishment of the stand and 21 years after establishment of the trial. Microdensitometry was used to record variations in wood density, whereas fibre properties and kraft pulp strength properties were measured on laboratory-made batches of unbleached kraft pulp. The main conclusion of the investigation is that a birch shelterwood has only a minor influence on the wood and fibre properties of sheltered Norway spruce and that the resulting consequences for kraft pulping are moderate. Length-weighted mean fibre length was significantly affected only by growth rate. It was 1.75 mm, or 6-13% lower, for trees showing a low growth rate than for all other trees. Tensile index was already high before refining, 85-95 Nm g-1, and the increase due to beating was similar for all shelterwood densities and growth rate classes. At 2000 beating revolutions, there was a strong negative correlation between tear index and the proportion of fibres shorter than 0.20 mm. The volume of wood required to produce 1 t of kraft pulp was almost identical, 5.4 ± 0.1 m3 t-1, for sheltered and unsheltered spruce. Norway spruce growing without shelter produced more pulp per hectare in all fibre length classes, but the difference was greatest, 56-59% compared with sheltered spruce, for the longest fibres (i.e., longer than 3 mm).
A comparison of pre-European settlement (1857) and current (1981-1995) forest composition in central Ontario
Authors: Jackson Scott M , Pinto Fred , Malcolm Jay R , Wilson Edward R
Published: April 2011

Presettlement forest composition along a 278 km long transect through central Ontario was recreated from Ontario land survey notes (1857) and compared with existing forest composition as derived from Forest Resource Inventories (1981-1995). Trends through time were analyzed by means of detrended correspondence analysis and univariate statistics (paired t tests and Wilcoxon matched-pair signed-ranks tests). Ordinations based on the first tree taxon listed in a stand and on all tree taxa provided similar results. The eastern half of the transect was initially dominated by boreal conifers, whereas the western half supported stands typical of Ontario's Great Lakes - St. Lawrence (GLSL) region. Significant reductions of yellow birch (Betula alleghaniensis Britt.), balsam fir (Abies balsamea (L.) Mill.), and eastern white cedar (Thuja occidentalis L.) and significant increases of poplar (Populus spp.) and white birch (Betula papyrifera Marsh.) were observed within the boreal half. A significant reduction in eastern white cedar and an increase poplar were observed in the western half. Changes in the boreal region strongly support previous studies conducted over shorter time periods and may be attributed to clear-cut harvesting. The persistence of shade-tolerant hardwoods within the GLSL region can be attributed to the prevalence of small-scale disturbances associated with partial-cut harvesting systems.
Estimating mapped-plot forest attributes with ratios of means
Authors: Zarnoch S J , Bechtold W A
Published: April 2011

The mapped-plot design utilized by the U.S. Department of Agriculture (USDA) Forest Inventory and Analysis and the National Forest Health Monitoring Programs is described. Data from 2458 forested mapped plots systematically spread across 25 states reveal that 35% straddle multiple conditions. The ratio-of-means estimator is developed as a method to obtain estimates of forest attributes from mapped plots, along with measures of variability useful for constructing confidence intervals. Basic inventory statistics from North and South Carolina were examined to see if these data satisfied the conditions necessary to qualify the ratio of means as the best linear unbiased estimator. It is shown that the ratio-of-means estimator is equivalent to the Horwitz-Thompson, the mean-of-ratios, and the weighted-mean-of-ratios estimators under certain situations.
The determinants of forest land prices: an empirical analysis
Authors: Aronsson Thomas , Carlén Ola
Published: April 2011

In this paper, we estimate a forest land price model using micro data, where the equilibrium price is interpretable as the outcome of a trading game between the buyer and seller. A novelty of the empirical analysis is the recognition that the forest land price, which has been agreed upon by the buyer and seller, may depend on variables characterizing the buyer's and seller's preferences and choice sets. The results imply that forest land prices are not only determined by land related variables (e.g., the land size, timber volume, and site productivity), they also depend significantly on buyer and seller characteristics.
Calculation of mean body temperature
Authors: Livingstone S. D.
Published: April 2011

Four young male subjects were exposed for 1 h to environmental temperatures of 8.5 °C, 14.0 °C, and 20.0 °C while lying on a rope mesh cot. During exposure they wore swimming trunks only. Heat production, skin temperature at seven locations, and rectal temperature were measured. Mean body temperatures (MBT) and heat debts were calculated from Burton's equations and also from equations determining radiative, convective, and evaporative heat losses. It was found that a linear equation with constant coefficients, such as Burton's, for measuring MBT does not allow for the fact that in the non-steady state the body continues to lose heat even though the skin temperature is relatively constant. During the initial period of cold exposure the coefficient of skin temperature when calculating MBT should be much smaller than at later stages in the cooling.
Sleeping time and mortality of rats administered acetylsalicylic acid and barbiturates
Authors: Coldwell Blake B. , Peters Josef M.
Published: April 2011

Acetylsalicylic acid was administered orally in doses from 0.2 to 1.9 g/kg with pentobarbital or thiopental, given intraperitoneally 1 h later, in doses ranging from 25 to 55 mg/kg, to overnight-fasted, male, albino rats. Both sleeping time and mortality were significantly increased with acetylsalicylic acid – barbiturate combinations. A dose-response relationship was observed in both sleeping time and mortality after acetylsalicylic acid and thiopental but only with the former after acetylsalicylic acid and pentobarbital. Starvation prolonged thiopental sleeping time. At equal doses, thiopental was more toxic than pentobarbital, when given separately and in combination with acetylsalicylic acid.
The role of carnitine in the animal exposed to cold
Authors: Delisle G. , Radomski M. W.
Published: April 2011

Changes in the concentrations of carnitine and its derivatives in the liver, heart, and skeletal muscle of rats exposed continuously to 4 °C for periods ranging up to 7 weeks were studied by using a specific enzymatic assay for carnitine. In heart and muscle the concentrations of free carnitine and fatty acylcarnitine were not elevated in cold-acclimatized animals, but that of acetylarnitine increased twofold. In the liver of cold-acclimatized rats, significant increases in all three of the carnitine fractions were observed. The concentration of fatty acylcarnitine in tissues from control animals was greatly elevated by starvation or a high-fat diet but, in contrast, the level was not increased in cold-exposed animals subjected to the same nutritional variants. Normal rats maintained at 22 °C and injected with daily doses of dl-carnitine for 14 days cooled more rapidly and survived for shorter times when exposed to −20 °C than animals injected with saline. Carnitine injections did not alter the oxygen consumption of normal or cold-exposed rats.
Acute changes in plasma volume, renin activity, and free aldosterone levels in healthy subjects following Fursemide administration
Authors: Rosenthal J. , Boucher R. , Nowaczynski W. , Genest J.
Published: April 2011

The effects of acute changes in plasma volume on renin release and plasma free aldosterone levels are not well understood. Our experiments demonstrate quantitative changes in the above-mentioned parameters following salt depletion. Plasma renin activity was assayed 10, 20, 60, and 120 min after the intravenous injection of Fursemide in healthy human subjects. Plasma free aldosterone levels and plasma volume were measured 60 and 120 min after injection. Plasma renin activity rose significantly after 10 min, as compared with control values, the highest values coinciding with peaks in urinary volume and sodium excretion as well as lowest urinary osmolality. The plasma aldosterone increase, moderate at 60 min, was significant at 120 min. Plasma volume measurements, 60 min after injection, decreased significantly, with a tendency to return to control values at 120 min. Plasma renin activity, measured by the new micromethod of Boucher at intervals of 2 to 70 min after the intravenous injection of Fursemide in rats, revealed, as in humans, a significant increase after 10 min. These data show that the increase in renin precedes that in aldosterone following the marked decrease in plasma volume due to acute diuresis and sodium loss.
Cholinolytics in the treatment of anticholinesterase poisoning. V. The effectiveness of Parpanit with oximes in the treatment of organophosphorus poisoning
Authors: Coleman I. W. , Patton G. E. , Bannard R. A. B.
Published: April 2011

The effectiveness of Parpanit in the treatment of organophosphorus poisoning was examined and compared with that of atropine sulfate. The potency of Parpanit was assessed in the mouse, rat, hamster, guinea pig, and rabbit against sarin, tabun, soman, CMPF, and DSDP in treatments in which the oximes P2S and TMB4 were used both singly and together. The effectiveness of the treatments utilizing both cholinolytics varied with the species used for assay, with the oxime used in combination, and with the nature and level of challenge of the organophosphorus inhibitors. The mean activity of Parpanit relative to atropine taken from a total of 102 trials indicated it to be 4.2 times as effective, with the potency ratio varying from 0.17 to 100 depending on the specific test. The acute oral toxicity of Parpanit in weanling rats was 2.9 g/kg (2.4–3.4). In a chronic toxicity study where daily oral doses as high as 1/5 LD50 were applied for 30 days, no evidence of accumulative effects could be found nor was there any evidence that the protective capacity of Parpanit against sarin was affected by the extended application of the drug.
Blood amino acid studies: Prediction of limiting amino acids in mixtures of dietary proteins
Authors: Rao S. Venkat , Noel F. J. , McLaughlan J. M.
Published: April 2011

Diets containing mixtures of cereals and protein supplements were fed ad libitum to male weanling rats 18 h daily for 5 days. The cereals consisted of rice, wheat, and corn, and the supplements included peanut, soy, cottonseed, and chick pea flours. Levels of plasma lysine, methionine, threonine, trytophan, leucine, and isoleucine were determined. Two methods designated as plasma amino acid (PAA) score and PAA ratio were tested for predicting the limiting amino acids in the diets utilizing the PAA data. Chemical score values were calculated from the amino acid content of the mixtures. Growth tests were also carried out with the diets, with or without a supplement of the amino acids indicated to be limiting by PAA score and PAA ratio methods. PAA ratios, PAA scores, and protein efficiency ratio data of rats indicated that lysine and threonine were equally limiting in rice–peanut, rice–soy, rice–cottonseed, rice – chick pea, wheat–peanut, and wheat–cottonseed diets. Plasma methods were also correct in showing that lysine was the limiting amino acid in corn–peanut, corn–soy, and corn–cottonseed mixtures. Plasma methods did not indicate a methionine deficiency when this amino acid was co-limiting with lysine and threonine. Chemical score failed to detect the threonine deficiency present in 8 of 12 diets. Limiting amino acids were not established for the corn – chick pea diet. It was interesting that the effective amino acid supplement for 8 of 12 diets required threonine in addition to lysine. It was concluded that the PAA methods are effective for predicting a deficiency of a single amino acid or of two co-limiting amino acids, but less satisfactory for predicting multiple amino acid deficiencies.
The magnitude of noradrenaline-induced thermogenesis in the bat (Myotis lucifugus) and its relation to arousal from hibernation
Authors: Hayward J. S.
Published: April 2011

The effect of subcutaneously injected noradrenaline upon the rate of oxygen consumption of bats (Myotis lucifugus) has been evaluated. Maximal responses were obtained with doses between 2 and 15 mg noradrenaline/kg. These doses increased the oxygen consumption to a mean of 7.93 ml O2/g per h from a pretreatment mean of 0.75 ml O2/g per h, representing a 10.6-fold increase. A survey of the literature shows that the magnitude of this response exceeds by several times the magnitude of response observed for any other species. There was no significant difference between the responses of nonhibernated and hibernated bats. The maximal rate of thermogenesis during arousal from hibernation was a mean of 10.57 ml O2/g per h. In comparison with this value, the maximum noradrenaline-induced thermogenesis of hibernated bats was 8.62 ml O2/g per h. This provides an estimate (81.6%) of the involvement of noradrenaline-induced thermogenesis in the process of arousal from hibernation. These findings corroborate previously reported evidence that hibernating bats exhibit a very high capacity for nonshivering heat production.
Composition and function of rat kidneys after transient normothermic ischemia
Authors: Keeler R.
Published: April 2011

A study has been made of the changes in composition and function of rat kidneys which had been subjected to transient normothermic ischemia. If the period of ischemia exceeded 1 h, potassium and magnesium were rapidly lost when the blood supply was reestablished. After 2 h of ischemia 30% of the tissue potassium and 39% of the magnesium were lost within 1 h of restoring the blood supply. After 2 days, tissue levels of cations and water rose to supranormal levels, reaching a maximum in 10 days. Restoration of normal composition required 4 to 6 weeks. Changes in composition were independent of organ hypertrophy and may have been related to tissue regeneration. Preventing the initial loss of potassium and magnesium did not significantly improve renal function or reduce mortality in the post-ischemic period. Most animals survived contralateral nephrectomy 4 days after 2 h unilateral ischemia but little improvement in function occurred until the 10th day. There was no evidence of function in the damaged kidney until contralateral nephrectomy was performed. The extent of the tissue electrolyte changes appeared to correlate with the functional impairment of the kidney.
Selective staining of secretory granules of adrenal medullary cells by silver methenamine: A light and electron microscopic study
Authors: Chang William W. L. , Bencosme Sergio A.
Published: April 2011

A reevaluation of the silver methenamine reaction as an electron stain has ensued from recent use of glutaraldehyde fixation alone. By this technique, three cell types of rat adrenal medulla were found: (i) the norepinephrine-containing cells showed selectively stained, irregular, black granules; (ii) the epinephrine-containing cells showed round, light-grey granules; and (iii) the third cell type showed round granules like those of epinephrine-containing cells, but black in color, similar to those of the norepinephrine-containing cells.
The electrical activity of intercostal muscles during quiet breathing in rabbits
Authors: Boyd William H.
Published: April 2011

The electrical activity and the circumstances of contraction of the internal and external intercostal muscles were studied during quiet breathing in non-anesthetized rabbits resting in the sternal semirecumbent position. The activity was recorded via clip electrodes implanted in both muscles in a series of interspaces. The greater part of the expiratory phase was characterized by slight activity in both the internal and external intercostals, preceded and followed by brief periods of inactivity. Inspiration was accompanied by continuous activity in both sets of muscles until the last 20–40 ms of that phase. It was found that both internal and external intercostals were active during inspiration, that their activity was at its greatest during this phase, and that this activity was characterized by a progressive increase in external intercostal activity. There was no evidence of reciprocal innervation of intercostal muscles in this study.
The influence of sugars upon hypersensitivity reactions
Authors: Thompson G. E. , Lowe D. B. , Mountain J. T.
Published: April 2011

Of 10 hexose and pentose sugars tested, three hexoses were found to improve consistently the 24-h survival of mice subjected to anaphylactic, histamine, or serotonin shock. Intravenous injection of polyvinylpyrrolidone reduced mortality to serotonin in the first 15 min after challenge. The results could not be explained on the basis of blood sugar level, serum osmolarity, the hexokinase or glucokinase systems, or by the dependence or independence of the sugar metabolism upon insulin. Protection appeared to be based upon both insulin and the phosphorylating system of the cell. It is suggested that the point of primary involvement is the glycolytic pathway of the neural or smooth muscle cells of the target organs.
Mitochondrial populations and succinic dehydrogenase in the heart of a hibernator
Authors: Zimny Marilyn L. , Moreland James E.
Published: April 2011

Thirteen-lined ground squirrels, Citellus tridecemlineatus, hibernating at 3–5 °C, awakened at 25–27 °C. Ten animals were killed for each experimental group as follows: (1) [Formula: see text] awakening to a body temperature of 9–13 °C, (2) 15 min awakening to 13–15 °C, and (3) 30 min awakening to 16–19 °C. At death a sample of the heart's apex was fixed in osmium tetroxide, dehydrated, and embedded in Vestopal-W for electron microscopy, and a 10% w/v water homogenate was made of the rest of the organ. Mitochondrial counts and measurements of dimensions were made on electron micrographs of at least 10 fields of each sample, and duplicate samples of homogenate were incubated at 37 °C and assayed spectrophotometrically for succinic dehydrogenase activity. When compared with data on control animals, during awakening the number of mitochondria per field decreased 25% (P < 0.01). Mitochondrial length increased 10% (P < 0.05) and width increased 28% (P < 0.01). In tissue obtained from hibernating animals, the succinic dehydrogenase activity was 60% of the control. This value decreased further to 42% of the control value during the first 7.5 min of awakening, thereafter returning to 94% of the control by 15 min.
Prolongation of certain effects of amphetamine by chlorpromazine
Authors: Borella L. , Herr F. , Wojdan A.
Published: April 2011

This study examines the effect of chlorpromazine on the hypermotility and hyperthermia induced by amphetamine in rats and correlates the effects observed with brain levels of the stimulant. Chlorpromazine antagonized these effects of amphetamine initially, and there was a dose–effect relationship in this antagonism. On the other hand, a combination of 7.2 mg/kg chlorpromazine and 8.5 mg/kg dl-amphetamine caused a delayed excitation and hyperthermia. The excitatory effect of this dose of amphetamine was prolonged by doses of chlorpromazine ranging from 1.9 to 7.2 mg/kg. Chlorpromazine modified the disposition of amphetamine as evidenced by considerably higher and more sustained brain levels of the stimulant in rats which received the combined treatment. The significance of these findings and the similarity of the interaction of chlorpromazine and imipramine with amphetamine are discussed.
The effect of radioprotective agents on erythropoiesis In irradiated mice
Authors: Vittorio P. V. , Watkins E. A. , Dziubalo-Blehm S.
Published: April 2011

The radioiron test (i.e. 59Fe uptake by blood, spleen, and liver) was used to evaluate the degree of protection (1 day after irradiation) and effect on recovery (7 days after irradiation) of the erythropoietic system when radioprotective agents were administered. In blood, spleen, and liver, AET administered prior to irradiation caused a decreased radiation effect on 59Fe uptake 1 day after irradiation, and a subsequent parallel return with the irradiated nonprotected group to the control value. This indicated that the early recovery by the protected group was probably due to less initial damage. The amount of protection afforded the erythropoietic system by sulfhydryl agents was in good agreement with irradiation survival studies and indicated that a good sulfhydryl radioprotective agent provided good protection, and a poor sulfhydryl radioprotective agent provided poor protection to the erythropoietic system. Thus the radioiron test is a good method to evaluate sulfhydryl compounds as radioprotective agents. Endotoxin demonstrated poor correlation between the early (1 day) erythropoietic effect and survival in irradiated mice, but recovery studies (7 days) showed much better agreement. The biological amine serotonin produced poorer initial protection to the erythropoietic system and slower recovery than AET even though the dose reduction factor of each was comparable. Serotonin must, therefore, protect other systems which then contribute to the eventual recovery of the erythropoietic system, and survival.
Alleviation of dietary cirrhosis with betaine and other lipotropic agents
Authors: Best C. H. , Ridout J. H. , Lucas C. C.
Published: April 2011

Supplementary betaine (as the hydrate, 0.63%) had a marked curative effect on cirrhosis of dietary origin. Male rats fed a hypolipotropic diet (protein 9%, provided as 6% extracted peanut meal, 6% soy protein) developed cirrhotic lesions of moderate severity in 4–6 months (established by laparotomy); 11 treatment diets were fed for about 7 months. The previously reported therapeutic effects of supplementary choline, methionine, or high protein were confirmed under new dietary conditions.
Influence of arterial oxygen tension on coronary vasodilator action of nitroglycerine
Authors: Cronin R. F. P. , Kovacs A.
Published: April 2011

In 11 anesthetized open-chest dogs, controlled perfusion of the left circumflex coronary artery was accomplished by shunting blood from the femoral artery and vein via a peristaltic pump. The pO2 of the perfusing blood was altered by changing the proportion of arterial and venous blood reaching the inflow side of the pump. Coronary perfusion pressure (CPP) was measured during stepwise reduction in the left circumflex coronary flow (LCF) over the range 120–10 cc/min. Resistance to coronary blood flowin the perfused myocardial segment was calculated as the ratio CPP/LCF and plotted against flow. Resistance-flow curves for the perfused coronary segments were obtained at pO2 values ranging between 95 and 25 mm Hg. Lowering the pO2 of the perfusing blood caused a reduction in coronary vascular resistance (CVR) in the perfused segment. When nitroglycerine was infused in a dosage of 3–6 μg/kg per minute, arterial blood pressure and heart rate were unaltered but CVR was reduced. The reduction in CVR was inversely proportional to the pO2 of the perfusing blood, the maximal vasodilator effect being observed at pO2 > 60 mm Hg. Nitroglycerine caused no significant change in coronary vascular resistance at pO2 < 39 mm Hg and did not prevent or delay the appearance of excess lactate in the coronary venous blood.
Reserpine inhibition of coronary arteriosclerosis
Authors: Carrier Jr. Oliver , Clower B. R. , Whittington-Coleman Peggy Joyce
Published: April 2011

A histological study of rabbit hearts from animals on a high-cholesterol diet (2% by weight) supplemented with vasopressin administration (2–4 units, three times a week) showed that after 7 weeks this regimen caused coronary arteriosclerotic lesions in three out of five animals. At the end of 10 weeks, 95% of the coronary arteries observed in five out of five animals had signs of arteriosclerosis. When, in addition to this treatment, the rabbits received 0.1 mg/kg reserpine per day, the incidence and severity of the lesions were greatly reduced. At 7 weeks only 10%, and at 10 weeks only 26% of the coronary arteries observed showed arteriosclerotic changes. These data indicate that reserpine has a protective action against atheromatous lesions which may be associated with its calcium-depleting effect.
A possible antidote for methanol poisoning in mice
Authors: Hassan A. , Monroe R. J. , Guthrie F. E.
Published: April 2011

Acetanilide was investigated as a possible antidote against methanol poisoning in mice. The drug afforded significant protection, when administered intraperitoneally at a dosage of 100 mg/kg 30 min after the oral ingestion of methanol (1100 mg/kg). When administered after longer periods, acetanilide was of less protective value. The degree of protection seems to parallel the amount of nonmetabolized methanol remaining in the organism. The antidotal property of acetanilide is believed to be related to the inhibition of alcohol oxidation.
Test of a possible influence of the drinking system of the lateral hypothalamus on the mechanisms controlling antidiuretic hormone
Authors: Mogenson G. J.
Published: April 2011

Rats that received electrical stimulation of the drinking system in the lateral hypothalamus did not excrete a significantly different volume of urine in the 2-h period following a stomach water load. It is concluded that electrical stimulation of the lateral hypothalamic region which evokes drinking does not also activate the antidiuretic system.
Mechanism of natriuresis following intravascular and extracellular volume expansion
Authors: Sonnenberg H. , Solomon S.
Published: April 2011

In clearance studies in rats, increases in filtration rate and electrolyte excretion were observed following both intravascular and extracellular fluid volume expansion. The inulin concentration ratio of proximal tubular fluid to plasma was decreased with extracellular expansion. Neither natriuresis nor fractional sodium reabsorption was related to the degree of intravascular expansion. Microperfusion studies demonstrated a decrease in proximal sodium reabsorption only when both intravascular and extravascular volumes were expanded; net sodium transport was not affected by a blood volume increase alone. From the data it is concluded that in the rat an increase in blood volume is followed by a rise of filtration rate and a fall of fractional reabsorption at a site distal to the proximal tubule, resulting in diuresis and natriuresis. If, in addition, the interstitial fluid compartment is expanded, a direct inhibition of the active transport component of proximal Na+ reabsorption occurs.
Stress-free parenteral injections in the rat
Authors: Gosbee John , Kraicer Jacob
Published: April 2011

A single subcutaneous insertion will stimulate the secretion of corticosterone. Rats pretreated by repeated daily subcutaneous needle insertions can be subsequently injected without the injection itself causing an increase in plasma corticosterone. This conditioning procedure will allow the study of the effect of parenterally administered materials in animals without the injection per se imposing an acute release of adenohypophyseal ACTH and of adrenal corticosteroids.
Inappropriate values of the juxtaglomerular index during changes in rat serum sodium levels
Authors: Sutherland L. E.
Published: April 2011

Extreme variations of dietary sodium are reflected in serum and urinary sodium levels. In rats fed a high-sodium diet and then abruptly switched to a low-sodium diet or fed a low-sodium diet and then switched to a high-sodium diet, the juxtaglomerular index was dissociated from both serum and urinary sodium values.
The effect of bradykinin on spontaneous and induced contractions of human uterine muscle in vitro
Authors: Belither Ann
Published: April 2011

The effects of the commercially available peptide bradykinin and its vehicle on spontaneous and induced contractions of human uterine muscle in vitro have been studied. It was found that the inhibitory effect noted by some authors is due to the vehicle. This effect is reversible.
Ubiquinone levels of human liver in health and disease
Authors: Phillips W. E. J. , Hoppner K. , Murray T. K. , Campbell J. S.
Published: April 2011

Total liver ubiquinone was not influenced by postmortem conditions when intact animals were exposed to room or refrigerator temperatures for periods of 24 h or a combined effect for 48 h. Liver ubiquinone declined progressively with duration of storage at −20 °C when liver tissue was stored but remained stable for 140 days when isolated nonsaponifiable material was stored. Recommendations are made for the routine handling of tissue samples for ubiquinone analysis. One hundred human livers were analyzed for ubiquinone. Age influenced liver ubiquinone content. Ubiquinone was low at birth and increased during the first year of life. No correlation was observed between ubiquinone concentration and primary cause of death, namely accidental, heart and coronary disease, cancer, respiratory diseases, and a miscellaneous group. Liver ubiquinone was not affected by the vitamin A status of humans. Extreme variations in ubiquinone concentration within any given age or disease group suggest that factors as yet not understood influence human liver ubiquinone levels.
Action of mast cell dischargers on the localization of Evans' blue
Authors: Savoie L. L.
Published: April 2011

A study was made of the influence of various mast cell dischargers on the normal localization of Evans' blue in the rat. It was shown that most of the mast cell dischargers decreased the renal or intestinal localization of the dye. Those which proved most potent for localizing the dye in the paw (one of the anaphylactoid shock organs) also significantly decreased the phagocytosis of Evans' blue in the spleen. Stilbamidine and, especially, hexadimethrine enhanced the accumulation of Evans' blue in the liver and the spleen; moreover, the latter completely inhibited blueing. When administered before Evans' blue, hexadimethrine localized the dye in the adrenals, the kidney, and the hypophysis, which are customary sites of hexadimethrine-induced lesions. The possible mechanism of the distribution of Evans' blue in various organs and the use of this technique to detect the localization of diseases are discussed.
The effect of repeated cold exposure of the hand on the reactivity of digital vessels
Authors: Gaskell Peter , Long Kathleen L.
Published: April 2011

One hand of each of 10 subjects was immersed in stirred water at 4 °C for 1 h per day, 5 days per week, for 3 weeks, to produce local acclimatization to cold. The opposite hand was immersed at the same time in water at 32 °C. The reactivity of digital vessels in a finger of each hand was measured as the increase in the critical opening pressure of the vessels in response to an intravenous infusion of noradrenaline at 2 and 5 μg/min. The reactivity of digital vessels in the test hand was compared with that in the control hand both before and after the repeated cold exposure of the test hand to see whether the cold exposure altered the reactivity of vessels in the test hand relative to that in the control hand. No evidence of such a relative change was obtained. Resting blood flow at 21 and 32 °C in the test hand was compared with that in the control hand both before and after the repeated cold exposure. No change in the relative flow rate in the two hands was observed as a result of the cold exposure. Roentgen studies of the hands did not reveal any effect of the repeated cold exposure on the mineralization of the bones of the hands.
Se-selenomethionine turnover as an index of protein metabolism during cold exposure of white mice
Authors: Yousef M. K. , Luick J. R.
Published: April 2011

The alterations of protein metabolism during cold acclimation were investigated in white mice by using the total body activity of methionine-75Se as an index. The protein turnover rate was increased 18% during acute exposure to 4 °C and 29% in cold-acclimated animals. The data on the restricted-fed mice at 4 °C temperature suggested that cold stress results in an increased protein turnover rate independent of increased food consumption. It is suggested that elevated energy metabolism during cold acclimation is partly due to an increased protein metabolism.
A direct-reading mercury thermometer for the wet bulb globe temperature index
Authors: Taylor N. B. G. , Kuehn L. A. , Howat M. R.
Published: April 2011

An instrument for direct measurement of the wet bulb globe temperature index (WBGT index) is described and tested. The instrument is a fluid analogue computer based on the mercury-in-glass thermometer and has no electronics. A linear correspondence was obtained between the readings of the instrument and the WBGT index calculated by the conventional method from the readings of individual wet bulb, dry bulb, and globe thermometers. The instrument provides a simple and valid method for measuring the WBGT index.
Some biochemical and physiological effects of AY-9944 on laying hens
Authors: Martin G. B. , Lupien P. J.
Published: April 2011

The action of trans-1, 4-bis(2-chlorobenzylaminomethyl)cyclohexane dihydrochloride (AY-9944) on laying hens was studied. When 2 μmoles of the drug per kilogram of body weight was administered (per os) daily during 20 days, egg production, although greatly reduced, was maintained at a level of approximately 20% compared with 70–80% for the control animals. With a dose of 10 μmoles, egg production was completely stopped within 10 days. Egg laying was gradually restored when treatment was stopped. The weight of whole eggs, yolks, and albumen was decreased by AY-9944, and egg yolks obtained from the treated hens showed important modifications in some of their sterols. A marked loss of feathers, accompanied by the appearance of a rough plumage, was also observed during treatment.
Enhancement of drug activity by chymotrypsin: The synergistic anti-inflammatory activity of chymotrypsin and prednisolone
Authors: Wohlman Alan , Ramirez Ramon I. , Avakian Souren
Published: April 2011

Chemically and physically induced inflammations in rats and guinea pigs were treated with a combination of chymotrypsin and prednisolone. The rate and degree of healing, which includes the elimination of hemorrhagic and edematous conditions, were compared with those in untreated controls as well as in those animals that received prednisolone or chymotrypsin alone. The combination of enzyme and steroid acted synergistically to promote healing and alleviate the inflammatory condition. The increased anti-inflammatory activity of the combination was independent of both the agents or methods used for wound induction and the animal species in which the lesions were produced.
Pharmacological modification of the vascular response to systemically administered thrombolytic enzymes (CA-7)
Authors: Roschlau Walter H. E. , Freedman Harvey J. , Miller Sandra L.
Published: April 2011

Thrombolytic enzymes are recognized as potent activators of the vasodepressor plasma kinins. In an attempt to modify the vascular response to systemic administration of such enzymes, the fungal protease CA-7 was used as a model. Vascular collapse was induced in control dogs by systemic administration of individually lethal doses of the enzyme. Pretreatment with the beta-adrenergic blocking agent propranolol did not prevent the occurrence of profound hypotension, but modified the typical vascular response to lethal doses of CA-7 by allowing arterial normotension to recur, followed by survival. The long-acting sympathomimetic metararninol was shown to be effective as a correcting agent of enzyme-induced vascular collapse, followed by survival of dogs treated with lethal doses of CA-7. The possible contributions from these findings to thrombolytic enzyme therapy are discussed.
The effect of inclusion of extraneous cellulose on the gastric emptying time in adult albino rats
Authors: Shurpalekar K. S. , Sundaravalli O. E. , Rao M. Narayana
Published: April 2011

Studies carried out on adult albino rats revealed that inclusion of 5 to 20% of extraneous cellulose in a finely divided form (particle size 40 μ, > 300 mesh) in a 26% casein diet did not significantly influence the gastric emptying time.
Comparison of fasting plasma amino acid patterns in the pig, rat, and chicken
Authors: Boomgaardt John , McDonald Bruce E.
Published: April 2011

Comparison of free amino acid levels in plasma (PAA) at 8, 12, 16, 20, and 24 h postprandial in pigs, rats, and chickens revealed differences between mammalian and avian species in the fasting metabolism of amino acids. PAA patterns during fasting were more variable for chickens than for either rats or pigs. There was a marked increase in the plasma lysine level in chickens (27.5 to 115.8 μg/ml) as fasting was extended from 8 to 24 h. Plasma lysine levels in pigs and rats, by contrast, increased from 14.2 to 19.5 μg/ml and 39.8 to 63.7 μg/ml respectively during the same period of fast. Plasma threonine and methionine levels also increased in chickens during fasting whereas the levels of these amino acids in pigs and rats decreased or remained unchanged during a 24-h fast. Extending the period of fast to 36 h in chickens and 48 h in pigs resulted in further small increases in the plasma lysine concentration.
Aminotriazole, thyroid function, and catecholamines in nephrogenic hypertension in rats
Authors: Fregly M. J. , Anton A. H.
Published: April 2011

Administration of graded doses of the antithyroid agent aminotriazole (ATZ) to male rats whose kidneys were bilaterally encapsulated with latex envelopes provided protection against the elevation of systolic blood pressure to the level of untreated, renal-encapsulated controls. The doses used were 5, 10, 50, and 250 p.p.m. mixed thoroughly into food. Blood pressures of the groups treated with either 50 or 250 p.p.m. ATZ were within the range of the non-encapsulated controls during the last 7 weeks of the 15-week experiment. Hypothyroidism accompanied administration of the highest dose of ATZ in that heart rate was reduced, and thyroid weight increased, beyond the levels observed for renal-encapsulated control rats. A sigmoid relationship was observed between heart to body weight ratio and systolic blood pressure for all rats. This relationship suggests that heart weight is unaffected by change in blood pressure until the threshold pressure of 150–159 mm Hg is reached. Beyond this threshold pressure, heart weight increased sharply to reach a level approximately 30% above that observed within the blood pressure range of 120–149 mm Hg. Treatment of hypertensive rats with ATZ failed to affect heart and adrenal norepinephrine and adrenal epinephrine concentrations, suggesting a lack of correlation between blood pressure and concentration of these catecholamines in the heart and adrenal glands.
A fat-mobilizing substance in chicken urine
Authors: Nir I. , Dimick Mildred K. , Lepkovsky S.
Published: April 2011

A fat-mobilizing substance (FMS) was extracted from the urine of fasting male and female chickens. Injection into chickens caused transient decreases in food intake and transient increases in plasma free fatty acids (FFA). These effects were accompanied by persisting decreases in plasma triglycerides. FMS also caused persistent decreases in plasma cholesterol and lipid phosphorus. Slight elevations of blood glucose occurred, but they were not statistically significant. FMS obtained from the urine of fed chickens by the same technique as that used with fasting chickens varied in its activity; at times it was similar to the FMS obtained from fasting chickens and at other times had little effect on plasma FFA and food intake. FMS elicited smaller increases in plasma FFA in laying hens than it did in males, possibly as a result of higher pre-injection levels in the hens. In contrast to findings in mammals, FMS was obtained from the urine of hypophysectomized chickens. Differences in response to FMS among mice, rats, and chickens are discussed.