PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “physiological characteristics”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1979

A review of research on genetic variation in physiological characteristics related to performance in dairy cattle.

Genetic influence on physiological characteristics ranges from single gene effects on amino acid substitutions in alternative forms of proteins to quantitative genetic effects on the amounts of enzymes and hormones. The number of loci involved in the control of quantitative variation in physiologically important substances is not known. A number of marker genes that affect blood antigens, serum and milk proteins, and enzymes have been identified in dairy cattle. However, relatively little is known about genetic effects on quantitative physiological traits in dairy cattle. Much more is known about the genetic control of hormones in laboratory animals. About 25% of the variation in milk production of dairy cows results from genetic differences. We need more studies of genetic influences on the various physiological and biochemical processes involved in the secretion of milk to reveal the mechanisms by which genetics influences the quantity and quality of milk produced by individual cows.

Animals↗
PubMed1979

DNA sequence similarity, cell wall mannans and physiological characteristics in some strains of Candida utilis, Hansenula jadinii and Hansenula petersonii.

The physiological characteristics, proton magnetic resonance spectra of cell wall mannans, DNA base composition and DNA sequence similarity of some strains of Candida utilis, Hansenula jadinii and Hansenula petersonii were examined. It was found that C. utilis was not distinguishable from H. jadinii by any of these criteria. These findings show the close genetic relationship between C. utilis and its perfect form H. jadinii. In contrast, H. petersonii was found to differ from C. utilis and H. jadinii on account of insignificant DNA reassociation as well as a number of other properties.

Ascomycota↗
PubMed1977

Physiological characteristics of skeletal muscles of dogs and cats.

Our purpose was to determine if physiological characteristics of skeletal muscles of dogs and cats are related to their histochemical and biochemical characteristics. Maximum oxygen consumption (VO2max) and blood flow (Q) at VO2max were determined for in situ muscles of dogs and cats. Compared to cat muscles, dog muscles per unit mass had higher succinate oxidase activities, VO2max's, and Q's at VO2max's. There are positive relationships between Q at VO2max and VO2max and between VO2max and succinate oxidase activity. The higher VO2max's and succinate oxidase activities of dog muscles are consistent with the presence in these muscles of only slow-twitch fatique-resistant fibers and fast-twitch fatique-resistant fibers, whereas up to 50% of the fibers found in cat muscles are fast-twitch fatiqable. Capillary-to-fiber ratios are 2.40-2.97 for dog muscles compared to 2.17-2.84 for cat muscles. Thus the two- to threefold higher Q at VO2max for dog muscles compared to cat muscles is not due to a greater number of capillaries.

Animals↗
PubMed1979

[Physiological characteristics during exertion of Swiss Alpine and urban pubertal children].

On account of standardized examinations of circulatory and respiratory responses during the ride on the bicycle ergometer the physiological characteristic of Swiss children population from 12 to 15 years of age living in alpin and urban habitats is reported. The average maximum oxygen intake per kg body weight was 49-50 ml/min for alpin boys, 45-47 for urban boys, 39-41 for alpin girls and 37-39 for urban girls. Except for somatometric values, there is no other significant difference between alpin and urban children from the physiological point of view. A comparison of presented results with data from abroad does not show any disadvantageous properties of cardiorespiratory functions for Swiss boys and girls.

Adolescent↗
PubMed1978

Physiological characteristics of free-living and parasitic stages of strains of Haemonchus contortus, susceptible or resistant to benzimidazole anthelmintics.

The effect of changes in genetic constitution (associated with developing benzimidazole resistance) on the physiological characteristics of Haemonchus contortus was investigated. Benzimidazole resistant H contortus were significantly more infective for sheep (20 per cent) than benzimidazole susceptible strains. Pathological changes were more severe in sheep infected with resistant H contortus as measured by packed cell volume, plasma protein concentration and haemoglobin levels. Faecal egg output was significantly higher for resistant strains as was the development and survival of eggs and free-living stages on pasture. Infective third stage larvae of benzimidazole resistant H contortus had a significantly faster exsheathment rate in rumenal fluid than did susceptible strains. These adaptive changes in response to continuing anthelmintic selection of resistant worm populations are discussed and the implications of these findings for worm control programmes indicated.

Animals↗
PubMed1978

[Comparative analysis of the morphologic and physiologic characteristics of nodes of Ranvier].

The intravital light microscopic study of the Ranvier node and paranodal structure was carried out in the isolated nerve fibres of Rana ridibunda. For the same fibres the electro-physiological characteristics obtained by the voltage-clamp method were compared with morphological ones. Definite correlations were found between the reduction of Na+ and K+ permeability constants and the degree of the paranodal myeline damage. The leakage conductance variations of the fibres under study did not exceed the normal range. High vulnerability of sodium and potassium systems seems to reflect a more complicated molecular organization of the electrically excitable Na+ and K+ channels as compared to nonexcitable leakage pathways. Essential changes of the Na+ channels properties caused by batrachotoxin were not accompanied by a visible alteration of the paranodal structure. The data obtained are discussed from the view point of modern ideas of the nature of axoglial relationships in myelinated nerve fibres.

Action Potentials↗
PubMed1976

Morphological and physiological characteristics of Gemmiger formicilis isolated from chicken ceca.

Morphological and physiological studies were made on chicken cecal isolates of the strictly anaerobic bacterial species Gemmiger formicilis. Structural features (phase-contrast and electron microscopy) of these microorganisms indicate they (i) are highly pleomorphic, (ii) possess a trilaminar cell wall like gram-negative bacteria, (iii) exhibit an unusual growth process characterized by polar swelling (resembling budding bacteria), and (iv) grow into elongated cells when exposed to a subinhibitory concentration of penicillin. The morphological data presented suggest that this species has a rod-shaped structure. These bacteria ferment a variety of sugars to produce formic, butyric, and lactic acids. There appear to be two groups of Gemmiger, one producing primarily lactate and the other producing formate as major fermentation metabolites. Growth of six strains in a basal medium, consisting of Trypticase, minerals, carbohydrate, Na2CO3 buffer, and cysteine as reducing agent, was stimulated by rumen fluid and yeast extract. Volatile fatty acids partially replaced the requirement for rumen fluid with some strains. Single deletions of vitamins (from a defined vitamin mixture) indicated that pantothenate, riboflavin, and thiamine were highly stimulatory to growth of the organism in a medium containing rumen fluid and Trypticase as source of vitamins. Other vitamin requirements were not studied.

Acetates↗
PubMed1976

Physiologic characteristics of 1,268 cultures of Pasteurella multocida.

Results of 29 physiologic tests are reported for 1,268 cultures of Pasteurella multocida from various hosts over a 10-year period. Of the cultures, 97 to 100% fermented galactose, glucose, mannitol, mannose, fructose, and sucrose, produced hydrogen sulfide and indole, and reduced nitrate; 6 to 91% fermented arabinose, glycerol, sorbitol, trehalose and xylose. Fermentation of dextrin, dulcitol, inositol, inulin, lactose, maltose, raffinose, rhamnose, and salicin, growth on MacConkey agar, change of litmus milk, production of urease and hemolysin, liquefaction of gelatin and motility were negative with 97 to 100% of the cultures. Of 200 cultures tested for catalase and oxidase, all were positive. Results of this study indicate that none of these tests will determine the host from which the culture was isolated.

Animals↗
PubMed1975

Physiologic characteristics of vestibular first-order canal neurons in the cat. II. Response to constant angular acceleration.

The physiologic response of first-order vestibular canal neurons, recorded within the internal auditory canal with glass microelectrodes, was studied in anesthetized cats. Neurons from all three canals were subjected to velocity trapezoidal rotations about the canal axis, and about different axes extending up to 90 degrees on either side of the canal axis in "roll" and 30 degrees on either side of "pitch." Each cell examined exhibited a spontaneous discharge and responded to constant angular acceleration in a fashion predictable from the direction of the in-plane acceleration vector and the known receptor hair cell polarization. Under conditions of prolonged constant acceleration, (5 degrees/s2 for 40 s) about 30% of the units which could be classified showed adaptation, 55% did not, and 14%, termed reverse adapting cells, demonstrated a fast rise followed by a slower, continual increase during stimulation. Secondary responses (undershoot or overshoot) were noted in most adapting neurons, but were absent in the reverse adapting group. Adapting neurons were distinguished from the nonadapting group by significantly lower resting rates, more irregular interspike-interval distributions, and greater sensitivity to acceleration. When compared with nonadapting neurons, reverse adapting cells had higher spontaneous rates, less irregular spike intervals, and higher sensitivities. The mean canal sensitivity to angular acceleration for all cells was 2 spikes . s-1/deg . s-2 (range 0.3-7.4 spikes . s-1/deg . s-2). Significant differences in mean sensitivity values between canal neurons were demonstrated, with those from the anterior being the most sensitive, followed by the posterior and horizontal canals, respectively. Time constants for all canals governing the transitory rise (or fall) in rate with constant acceleration averaged 3.8 s. Small differences in mean values were noted between canals but these were not significant. Incremental time constants were found to be slightly but significantly longer (mean = 3.9 s) than decremental time constants (mean = 3.6 s). Some cells showed different tine constants to many trials of one stimulus as well as to different levels of stimulus. Most canal unitary responses were approximately linearly related to stimulus magnitudes over the range of 2-18 degrees/s2. This being the case, the angle between the canal plane and plane of stimulus become the main determinant in the first-order neural response. Here, a linear cosine relationship descriged the three-dimentionsal unitary response curve: maximum canal response was elicited with rotation about the canal axis, while no response was evoked with rotation about an axis approximately 90 degrees to canal axis. Between these two extremes, the response of a cell was determined by the cosine of the angle between the canala axis and the axis of rotation.

Acceleration↗
PubMed1979

Physiological characteristics of trained Australian paraplegic and tetraplegic subjects.

Sixteen male Australian paraplegic and tetraplegic subjects competing at the 1977 FESPIC games underwent a physiological assessment. The assessment included a neurological examination, anthropometry, spirometry, maximum oxygen consumption using a wheelchair and motor driven treadmill and a 5 minute post exercise blood lactate. Eight subjects had won gold medals at international competitions for the disabled, and, at the time of testing, two of the subjects were world record holders in track and field events. Spirometry was consistent with other reported values with FVC and FEV1.0 being 4.94 and 4.25 l respectively. The cardiorespiratory data revealed a mean VO2max 2.04+/-0.64 l min-1, and 33.0+/-9.4 ml kg-1 min-1; VE STPD, 60.75+/-22.64 l min-1; maximum heart rate 179+/-20 b min-1 and post exercise lactate 11.73+/-1.94 mM. It was concluded that many physiological variables measured on the Australian subjects at rest and during maximum work were comparable to other trained disabled athletes.

Anthropometry↗
PubMed1976

Evaluation of 8 physiological characteristics of clinically isolated Staphylococci and Micrococci.

307 cultures of staphylococci and micrococci were isolated from clinical sources and were subjected to 8 different physiological tests for the recognition of pathogentic strains. These tests were as follows; catalase, oxidase, fermentation and oxidation of glucose and mannitol, v.p. and coagulase activity, heat resistance endonuclease, and lipase production. From the results obtained it can be concluded that for the recognition of pathogenicity of staphylococci, coagulase, heat resistance endonuclease and fermentation of mannitol should be carried out.

Bacteriological Techniques↗
PubMed1975

Immunological and physiological characteristics of the rapid immune hemolysis of neuraminidase-treated sheep red cells produced by fresh guinea pig serum.

The rapid hemolysis by fresh guinea pig serum known to occur with neuraminidase-treated sheep red cells has been investigated with respect to the immunological and physiological properties of the lytic process. The following observations were made: (a) The susceptibility to hemolysis is directly proportional to the amounts of neuraminic acid enzymatically released from the cell surface. Complement lysis is mediated through binding of an IgM antibody protein to membranes of neuraminidase-treated cells. (b) Hemolysis is relatively temperature-independent above about 28 degrees C but below which a decrease in the hemolysis rate occurs. Arrhenius activation energies above and below the transition temperature were therefore found to be different. (c) Colloid osmotic swelling of neuraminidase-treated high potassium sheep red cells with a chloride ion concentration ratio near unity suspended in high potassium medium could not be prevented by sucrose. Hence, colloid osmotic swelling before lysis must be due to the entrance of sucrose and water since sucrose was the only external solute not at equilibrium. (d) From the rate of swelling and the apparent flux of sucrose under nonsteady state conditions an experimental permeability coefficient (P) for sucrose of 3-10(-8) cm-s-1 was computed. Comparison with a theoretical P of 4-10(-6) cm-s-1 for sucrose freely permeating through a single, hypothetical membrane lesion per cell of 60 A effective diameter indicates a membrane lesion which permits the passage of solutes larger than cations, but clearly constrains the free diffusion of sucrose.

Animals↗
PubMed1975

Physiologic characteristics of vestibular first-order canal neurons in the cat. I. Response plane determination and resting discharge characteristics.

The response plane and resting rate characteristics of first-order, vestibular, semicircular canal neurons were studied in 67 cats under sodium pentobarbital anesthesia using single-unit recording techniques in the eighth nerve. Five hundred fifty-nine units were classified as to the canal they were associated with by employing an identification technique based on physiologic response patterns to brief, high-level (up to 250 degrees/S2) angular accelerations delivered in various head positions. All horizontal canal neurons had increased firing rates to ampullopetal and all vertical canal units to ampullofugal endolymph flow. The average observed roll and pitch null points for each canal were used to determine the average sensitivity vectors for the right horizontal, anterior, and posterior canals. These sensitivity vectors were at a variance of 4.6-10.2 degrees from those predicted by anatomical measurements (3). The mean resting discharge characteristics of 318 first-order neurons was 36.0 spikes/s (range 0.50-114 spikes/s). No significant difference was noted between horizontal and anterior canal neurons on horizontal and anterior canal neurons on the basis of resting rate. The resting rate of the posterior canal neuron population was significantly lower. The regularity of the resting discharge varied in all three canals and the average coefficient of variation was 0.238 for the population, with a range of 0.298-1.030. The population distribution of all resting-rate statistical parameters appeared to be unimodal, indicating that first-order canal neurons may not be broken into discrete populations on the basis of resting-rate characteristics. Of 47 adequately examined first-order canal neurons, 25 demonstrated a repeatable and predictable alteration in their resting discharge as their position to gravity was reoriented. This alteration was usually nonadapting and varied in magnitude according to the degree of tilt and original starting position. Of 25 canal gravity units, 4 had nearby units from the same canal which were unresponsive to gravity, suggesting the effect was due to a limited distortion of the crista or cupula rather than an overall displacement of the cupula.

Acceleration↗
PubMed1977

Physiological characteristics of a champion runner: age 77.

A world champion distance runner, age 77, was evaluated in various anthropometric, pulmonary, hematological, and cardiorespiratory measures. The subject held 14 recognized world records in track and distance running for competitors aged 74, 75, and 76 years and had 11 records pending for the 77-year-age category. He was the 1975 National AAU Master's class IV-b champion in the 400, 800, 1500, 5000 and 15,000 meter races. The results of the physiological measures taken exceeded those of a more sedentary population of comparable age, were similar to reported values for other Master athletes, and approached the standards noted for much younger runners. The largest age-related decrements were observed in measures of maximal heart rate, maximal pulmonary ventilation, and maximal oxygen consumption. The general reduction in aerobic power was attributed to a combination of pulmonary, circulatory, and metabolic factors in addition to training consideration.

Aged↗
PubMed1979

Physiological characteristic and energy balance of Klebsiella aerogenes in a multistage tower fermentor.

Biomass growth, consumption of carbon and energy source, specific rates of formation of metabolic byproducts, biomass yield referred to the C-source and to oxygen, respiration rate and the value of RQ were studied in Klebsiella aerogenes CCM 2318 (on a synthetic glucose medium) at different specific growth rates. Maintenance coefficients and the total energy balance of the cultivation process were evaluated for a multistage tower fermentor with a defined interstage mixing. The results pointed to changes in both glucose metabolism and the physiological state of the population, brought about by changes in specific growth rate. As compared with a chemostat, the culture was found to exhibit a different physiological character is stages 1 and 4 despite a considerable interstage mixing.

Acids↗
PubMed1976

Physiological characteristics of chemostatically grown Citrobacter freundii as a function of the specific growth rate and type of nutrient limitation.

Citrobacter freundii was grown aerobically in a chemostat on a mineral medium with galactose or glucose as carbon and energy sources under limitation by carbon or nitrogen source respectively. At various specific growth rates ranging from 7 to 95% mumax the culture in steady state was analysed and growth yield, specific metabolic rate of substrate utilization, intracellular concentration of pyruvate, ATP, ADP, AMP and energy charge were determined and plotted as functions of dilution rate. In all four types of experiments the physiological state of cells remained practically independent of dilution rate up to D=0.6 mumax, and at a given specific growth rate nearly independent on mumax and type of limitation. At approximately D=0.6 mumax, which is close to the maximum output dilution rate Dm, the physiological state of the cells changed: growth yields decreased and intr cellular pyruvate and adenylates concentrations increased. Consequently, in a given medium two dilution rates exist at which growth rate dx/dt is the same but the physiology of the population is quite different.

Adenosine Diphosphate↗