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PubMed1982

Physiological characteristics of the solitario-parabrachial relay neurons with tongue afferent inputs in rats.

Among 180 units in the solitary tract nucleus (NTS) of rats, 34 solitario-parabrachial relay neurons (SP neurons), were identified by antidromic activation from the parabrachial nucleus. The SP neurons were classified into two groups, fast and slow, according to their antidromic latencies. The responsiveness of the SP in comparison with non-SP neurons was studied by electrical stimulation of three tongue nerves: the lingual (L), chorda tympani (CT) and glossopharyngeal (G) nerves. About half the SP neurons produced a single spike with an orthodromic latency of 2-5 ms, while about one third of them discharged more than two spikes. A few neurons gave rise to a long-lasting discharge consisting of five or six spikes. Some SP neurons were excited by stimulation of the tongue afferents with a low stimulus intensity, but other SP neurons produced spikes at only very high voltages. Fast SP cells were not differentiated from slow SP cells, except that latency of orthodromic responses to CT stimulation was significantly shorter in the former than in the latter (P less than 0.05, Mann-Whitney U-test). Locations of the SP and non-SP neurons, reconstructed histologically, indicate that they do not distribute evenly throughout the mediolateral extent at the rostral pole of the NTS, but clustered in its medial half.

Afferent Pathways↗
PubMed1988

Instability of protease production in a rel+/rel- -pair of Bacillus licheniformis and associated morphological and physiological characteristics.

A naturally occurring relaxed/protease-producing (A-type) versus stringent/not protease-producing (B-type) pair of an industrial Bacillus licheniformis has been characterized; either of the two types can convert into the other. Both types can sporulate, grow anaerobically, grow at 56 degrees C and reduce nitrate; morphologically, they can easily be distinguished by cell- and colony-shape. They differ in the ability to use 12 substrates, as determined in API-tests. The two types are remarkably different in their content of extrachromosomal elements (A-type: 2; B-type: 4); furthermore, they differ in their rel-status (A-type: relaxed; B-type: stringent). We propose that the differences in the ability of the two types to use different substrates probably are due to integration/extrusion of the extrachromosomal elements in and out of the chromosome, distorting or restoring a number of genes, together with induction of certain catabolic genes that are under control of the rel-system.

Aerobiosis↗
PubMed1980

Physiological characteristics of young well-trained swimmers.

The purpose of this study was to describe body composition, muscular strength, pulmonary function, and aerobic capacity of young swimmers, after 6 years of training. Twelve male members of a competitive swim team, ranging in age for 13 to 16 years, served as subjects. Each subject was measured on 2 separate days at approximately the same time of day on each occasion. On day one, body composition, muscular strength, TLC, FVC, FEV1.0, FRC, RV, and resting DLc0 were determined. On day 2, height, weight, VE max Hr max, and VO2 max were measured. Results indicated that children who train to swim competitively: (1) are lower than average in percent body fat (10.8%) as determined by hydrostatic weighing, (2) are muscularly fit as indicated by the Oregon Cable-Tension Strength Test, and (3) have cardiorespiratory capacities which are greater than one would expect to see in untrained youth of similar ages.

Adolescent↗
PubMed1994

Selecting and designing cell lines for improved physiological characteristics.

We have developed several approaches to create cell lines with improved characteristics in cell culture. In some cases it has been possible to isolate natural variants with useful properties. Cholesterol independent variants of the mouse NSO myeloma cell line were isolated by cloning in a selective medium. A glutamine independent variant of a hyridoma was isolated by continuous (chemostat) culture under glutamine limited conditions in the presence of glutamate. Choline independent cells were isolated from a choline limited chemostat. In an alternative approach to modifying cell behaviour, we have used recombinant DNA techniques to introduce the glutamine synthetase (GS) gene to a hybridoma. This resulted in glutamine independence and increased productivity.

Animals↗
PubMed1994

Seasonal fluctuations of selected physiological characteristics of elite alpine skiers.

The effects of heavy resistance training and jumping exercise were examined during the 1989-1990 season in 12 international level alpine skiers. The athletes were tested before, during, immediately after training and during the period off training (June, July, October 1989, April 1990). Their mechanical behaviour was investigated using firstly squat jumps performed without (SJ) or with low extra loads (20 kg, SJ20kg) and high extra loads (equivalent to body mass on the shoulders, SJbm) and secondly 15-30 s continuous jumping. These tests allowed the assessment of explosive dynamic strength production (SJ and SJ20kg), slow dynamic strength (SJbm) and maximal mechanical power (continuous jumping). The training adopted resulted in specific changes in neuromuscular performance; in fact all the variables studied showed a significant improvement (P < 0.01) from the beginning compared to the end of training. The range of improvement was between 55.4% (SJbm) and 12.5% (average power during 15-s continuous jumping). The enhancement of SJ had become significant by July. Surprisingly, even when no strength or jumping training was performed during the competition period (November-April), no deterioration in the neuromuscular performance was observed, there being no significant difference between the test values obtained in October 1989 and April 1990. It was concluded that the demanding competition programme of alpine skiers may provide a training stimulus adequate to maintain the neuromuscular improvement induced by training throughout the competition season.

Adult↗
PubMed1983

Arterio-venous epidural shunting in epidural bleeding radiological and physiological characteristics. An experimental study in dogs.

In order to test the possibility suggested in previous studies that the long bleeding time and the large bleeding volume observed in experimental epidural bleeding can be explained by the development of an arterio-venous shunt, water soluble X-ray contrast was injected into the epidural space in dogs during an epidural bleeding in progress. It was found that the contrast medium left the epidural space through diploic veins in the cranial bone to the neck veins. By draining off epidural blood the arterio-venous shunt counteracts the intracranial pressure tamponade developing in intradural bleeds and thus prolongs bleeding. Perfusion experiments showed the absorption capacity for saline to be about 20 times as large in the epidural space as in the CSF space. While there was no apparent absorption limit for blood in the epidural space the absorption capacity for blood of the subarachnoid space became progressively saturated, leading to a continuously increasing CSF outflow resistance and CSF steady-state pressure. A theory for the formation of epidural haematoma is proposed which in essence implies that the epidural shunt is a major determinant of the clinical outcome of an epidural bleeding.

Animals↗
PubMed1977

Structural and physiological characteristics of some sheathed bacteria.

The fine structure and growth of two gram-negative and two gram-positive strains of sheathed bacteria, isolated from activated sludge, have been studied. Their anatomy is quite different from Sphaerotilus natans. The cells are rectangular, tightly joined together, non-motile and enclosed by a sheath which is thin in the gram-negative strains and rather electron-dense in the two larger gram positive strains. The four strains grow slowly and form pink filamentous flocs in liquid media.

Bacteria↗
PubMed1990

Distribution of cells in different stages of the cell cycle and some age-related physiological characteristics in dependence on the dilution rate in chemostat cultures of Candida utilis.

Position of cells in their cell cycle was determined microscopically in chemostat cultures of Candida utilis. Proportion of cells in phase G1 decreased in a linear manner from 86% to 58% with dilution rate. Proportion of cells in phase S increased in the same range of D from 5.6 to 13.5% and in the (G2 + M) phase from 8.4 to 28.5%, again linearly. Differential centrifugation was used to separate chemostat cultures to mother and daughter cells. Analyses showed that, relative to mother cells, daughter cells contain 2.1-11.9% more protein and 25.5-34.6% more RNA in dry matter. Their mass is 34.4-5.6% lower and volume is 154-19% smaller.

Candida↗
PubMed1997

Physiological characteristics and growth behavior of single and double hydrogenase mutants of Desulfovibrio fructosovorans.

The presence of one periplasmic [NiFe] hydrogenase, one periplasmic [Fe] hydrogenase, and one cytoplasmic NADP-reducing hydrogenase has been previously established in Desulfovibrio fructosovorans. In the present work, marker-exchange mutagenesis was performed to determine the function of the tetrameric NADP-reducing hydrogenase encoded by the hndA, B, C, and D genes. The mutations performed were not lethal to the cells, although the H2-dependent NADP reduction was completely abolished. The double-mutated DM4 (DeltahynABC, DeltahndD) strain was still able to grow on hydrogen plus sulfate as the sole energy source. The growth may have occurred under these culture conditions because of the presence of the remaining [Fe] hydrogenase. The cells grew differently on various substrates depending on whether fructose, lactate, or pyruvate was used in the presence of sulfate. The (hnd mutant growth rates were 25-70% lower than those of the wild-type strain, although the molar growth yield remained unchanged. By contrast, mutants devoid of both [NiFe] hydrogenase and NADP-reducing hydrogenase had 24-38% lower growth yields and showed a corresponding drop in the growth rates. We concluded that each of the three hydrogenases may contribute to the energy supply in D. fructosovorans and that the loss of one enzyme might be compensated for by another. However, the loss of two hydrogenases affected the phosphorylation accompanying the metabolism of fructose, lactate, and pyruvate.

Adenosine Triphosphate↗
PubMed2004

Single-unit responses to kinetic stimuli in New World monkey area V2: physiological characteristics of cue-invariant neurones.

In order to investigate the neural processes underlying figure-ground segregation on the basis of motion, we studied the responses of neurones in the second visual area (V2) of marmoset monkeys to stimuli that moved against dynamic textured backgrounds. The stimuli were either "solid" bars, which were uniformly darker or lighter than the background's average, or kinetic ("camouflaged") bars, formed by textural elements that matched the spatial and temporal modulation of the background. Camouflaged bars were rendered visible only by the coherent motion of their textural elements. Using solid bars, we subdivided the population of marmoset V2 neurones into motion-selective (uni- and bi-directional units, 73.3% of the sample) and weakly-biased (26.7%) subpopulations. The motion selective subpopulation was further subdivided into cue-invariant neurones (units which demonstrated a similar selectivity for the direction of motion of the solid and camouflaged bars) and non-cue-invariant neurones (units which showed selectivity to the direction of motion of solid bars, but had weak or pandirectional responses to camouflaged bars). Cells with cue-invariant responses to these stimuli were as common in V2 as in the primary visual area (V1; approximately 40% of the population). In V2, neurones with cue-invariant and non-cue-invariant motion selectivity formed distinct populations in terms of classical response properties: cue-invariant neurones were characterized by a sharp axis of motion selectivity and extensive length summation, while the majority of non-cue-invariant neurones had broader motion selectivity and were end-stopped. In the light of previous studies, these different constellations of classical response properties suggest a correlation with more traditionally recognized categories of V2 units and modular compartments. The responses of V2 cells to kinetic stimuli were slightly delayed relative to their responses to luminance-defined stimuli.

Action Potentials↗
PubMed1984

Primary hemochromatosis: anatomic and physiologic characteristics of the cardiac ventricles and their response to phlebotomy.

M-mode and 2-dimensional echocardiography and gated equilibrium blood pool imaging (rest and exercise) were used in 10 patients with primary hemochromatosis to characterize the spectrum of pathophysiologic abnormalities of the cardiac ventricles and to determine the response to chronic therapeutic phlebotomy. Dilated and restrictive cardiomyopathic patterns were identified in 1 patient each, but our data do not permit conclusions on when in the natural history a given pattern becomes overt. On entry into study, 3 patients had normal ventricles and 7 had ventricular abnormalities on echocardiography and blood pool angiography. In 2 of the latter patients, biventricular dysfunction and increased left ventricular (LV) mass normalized after phlebotomy; 1 patient achieved a normal LV response to exercise. Of the 4 patients with isolated abnormal LV ejection fraction responses to exercise, the EF normalized in 2 after phlebotomy. In 1 patient, isolated right ventricular enlargement and dysfunction (echocardiographic and radionuclide imaging) normalized after phlebotomy. Thus, primary hemochromatosis can effect LV and RV size and function; clinically occult cardiac involvement can be identified by echocardiography and equilibrium blood pool imaging; therapeutic phlebotomy can ameliorate or reverse the deleterious effects of excess cardiac iron deposition which appears to exert its harm, at least in part, by a mechanism other than irreversible connective tissue replacement.

Adult↗
PubMed1993

Physiologic characteristics of coronary artery bypass grafts.

To investigate the hemodynamic characteristics of arterial grafts for coronary artery bypass grafting, we measured phasic pressure and flow patterns in three types of grafts in a canine model (n = 18). A graft from the ascending aorta (AAG), a graft from the descending aorta at the first lumbar level (DAG), analogous to a right gastroepiploic artery, and an internal thoracic artery (ITA) were anastomosed to each other. The composite graft was anastomosed to the left anterior descending coronary artery, and then the left anterior descending coronary artery was ligated. Before grafting, the AAG showed high sustained diastolic pressure, but the ITA and DAG showed rapid fall of diastolic pressures. Mean diastolic pressures were 83 +/- 2, 72 +/- 3, and 57 +/- 2 mm Hg in the AAG, ITA, and DAG (p < 0.05). Free flow in the AAG was markedly greater than in the ITA or the DAG. After grafting to the left anterior descending coronary artery, no changes were observed in diastolic pressures compared with the pregrafting values. Total blood flows were 72 +/- 6, 80 +/- 7, 57 +/- 7, and 44 +/- 6 mL/min in the left anterior descending coronary artery, AAG, ITA, and DAG, respectively. There were no differences in systolic graft flow between the three types of grafts. Diastolic blood flow in the ITA (29 +/- 4 mL/min) and DAG (18 +/- 3 mL/min) was smaller than in the AAG (48 +/- 4 mL/min) (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗