Activity Of Different Groups Research Articles

Androgen and estrogen stimulation of ornithine decarboxylase activity in mouse kidney

In the present work, the activity of mouse renal ornithine decarboxilase (ODC) from CBA female mice was used as a biological marker to detect (anti)androgenic activity of different groups of endocrine disruptors and steroids. Daily injections of testosterone or dihydrotestosterone (DHT) into 60 day old female mice for 4 days increased renal ODC activity in a dose-dependent manner that reached up to 100-fold (testosterone) or 250-fold (DHT) above the baseline when the highest dose, 200 μg/mouse, was used. Administration of flutamide concurrently with testosterone (75 μg/mouse) caused a potent decrease of ODC induction in a dose-dependent manner, suppressing the enzyme activity at the doses of 0.1 and 0.5 mg/mouse by about 88 and 95%, respectively. In contrast, estradiol at the doses of 0.5 and 1 mg/mouse induced a significant stimulation of renal ODC activity in a dose-dependent manner when it was given alone or in combination with testosterone. Using a sensitive increase in ODC activity in response to androgens as an end point, we did not detect an antiandrogenic effect of several antiandrogens, such as cyproterone acetate, spironolactone, p, p′DDE and vinclozolin. Also, none of these antiandrogens were able to change the basal level of renal ODC activity, with the exception of cyproterone acetate that at a dose of 0.1 mg/mouse stimulated ODC activity. The data obtained suggest that mouse renal ODC from CBA females is not strictly androgen-specific and cannot be used for estimation of antiandrogenic effects of compounds having an affinity to different types of receptors.

Differential suppression of upper airway motor activity during carbachol-induced, REM sleep-like atonia.

Microinjections of carbachol into the pontine tegmentum of decerebrate cats have been used to study the mechanisms underlying the suppression of postural and respiratory motoneuronal activity during the resulting rapid eye movement (REM) sleep-like atonia. During REM sleep, distinct respiratory muscles are differentially affected; e.g., the activity of the diaphragm shows little suppression, whereas the activity of some upper airway muscles is quite strong. To determine the pattern of the carbachol-induced changes in the activity of different groups of upper airway motoneurons, we simultaneously recorded the efferent activity of the recurrent laryngeal nerve (RL), pharyngeal branch of the vagus nerve (Phar), and genioglossal branch of the hypoglossal (XII) and phrenic (Phr) nerves in 12 decerebrate, paralyzed, vagotomized, and artificially ventilated cats. Pontine carbachol caused a stereotyped suppression of the spontaneous activity that was significantly larger in Phar expiratory (to 8.3% of control) and XII inspiratory motoneurons (to 15%) than in Phr inspiratory (to 87%), RL inspiratory (to 79%), or RL expiratory motoneurons (to 72%). The suppression in upper airway motor output was significantly greater than the depression caused by a level of hypocapnia that reduced Phr activity as much as carbachol. We conclude that pontine carbachol evokes a stereotyped pattern of suppression of upper airway motor activity. Because carbachol evokes a state having many neurophysiological characteristics similar to those of REM sleep, it is likely that pontine cholinoceptive neurons have similar effects on the activity of upper airway motoneurons during both states.

Repeated activation of neurotensin receptors sensitizes to the stimulant effect of amphetamine

Effects of repeated intracerebroventricular microinjections of 18 nmol/10 μl of neurotensin, [ d-Tyr 11]neurotensin, or saline were tested on motor activity in different groups of rats. One week after the fourth central injection, sensitivity to the behavioral stimulant effect of amphetamine (1 mg/kg, i.p.) was tested. As previously reported, neurotensin attenuated motor activity while [ d-Tyr 11]neurotensin when compared to saline produced an initial suppression followed by an excitation. Despite such different behavioral effects, both peptides produced sensitization to the stimulant effect of amphetamine. These results show that repeated activation of neurotensin receptors produces long-lasting changes in responsiveness to a psychostimulant drug.

Development of piezoelectric composites for transducers

For the past decade and a half, many different types of piezoelectric ceramic-polymer composites have been developed intended for transducer applications. These diphasic composites are prepared from non-active polymer, such as epoxy, and piezoelectric ceramic, such as PZT, in the form of filler powders, elongated fibers, multilayer and more complex three-dimensional structures. For the last four years, most of the efforts have been given to producing large area and fine scale PZT fiber composites. In this paper, processing of piezoelectric ceramic-polymer composites with various connectivity patterns are reviewed. Development of fine scale piezoelectric composites by lost mold, injection molding and the relic method are described. Research activities of different groups for preparing large area piezocomposites for hydrophone and actuator applications are briefly reviewed. Initial development of electrostrictive ceramics and composites are also

Regulation of Rat Pancreatic Nuclear Triiodothyronine Receptor by Glucocorticoid

The nuclear T3 receptors in rat pancreas exhibit a characteristic maturation pattern during development and are subjected to autologous regulation by thyroid hormones. To see if glucocorticoids also regulate T3 receptors in the pancreas, rats at various age groups were subjected to experimental conditions that altered their glucocorticoid status and the corresponding changes in nuclear T3 receptors, and exocrine enzymes in their pancreata were evaluated. Hydrocortisone administration to normal suckling and weaning rats did not change total T3 binding capacity or the dissociation constant as measured at 30 degrees C (Kd30). A significant increase in the degree of occupancy of the T3 receptor was found at 5-10 days after treatment with hydrocortisone (42.2 + 4.1% vs. 19.2 + 2.0%). T3 binding capacity and exocrine enzyme concentrations were significantly reduced in both adrenalectomized (Adx) pups and adults, indicating a continuous dependency on glucocorticoid from preweaning to adulthood. In adrenalectomized rat pups, either T4 or glucocorticoid replacement alone restored T3 binding capacity and exocrine enzyme concentrations. T4 and glucocorticoid were given together to Adx rats, the level of stimulation of both pancreatic T3 binding capacity and exocrine enzyme concentrations was found to be equal to the sum of the stimulation by each of these hormones when given alone. Furthermore, a good correlation was found between Bmax30 (Bmax measured at 30 degrees C, representing total sites) for T3 binding and exocrine enzyme activities in different groups following various experimental treatments. These findings provide further evidence that thyroxine can act directly on the rat pancreas presumably through the T3 receptor in regulating the postnatal development of the exocrine enzymes.

The use of protein synthesis inhibitors in the estimation of the contribution of halophilic archaebacteria to bacterial activity in hypersaline environments

Antibiotics affecting protein synthesis were used to differentiate between the activity of different groups of organisms (halophilic archaebacteria, eubacteria and eukaryotes) in water samples from hypersaline ecosystems. Anisomycin (inhibiting both archaebacterial halophiles and eukaryotes) can be used to quantitate the contribution of the archaebacterial halophiles to amino acid incorporation by the microbial community, when cycloheximide (inhibiting eukaryotic protein synthesis, but not affecting halobacteria) is used as a control. Both in saltern ponds at salinities above 300 g/1 and in Dead Sea surface water more than 95% of the amino acid incorporation activity was abolished by anisomycin, but not by cycloheximide. Inhibition by anisomycin was well correlated with inhibition by low concentrations of bile salts, which specifically affect bacteria of the Halobacterium group. Chloramphenicol (an inhibitor of eubacterial protein synthesis) quantitatively inhibited amino acid incorporation in saltern brines of relatively low salinity, but also caused significant (28–42%) inhibition at high salinities. Erythromycin was also found valuable in the estimation of activities of the different bacterial groups.

The use of protein synthesis inhibitors in the estimation of the contribution of halophilic archaebacteria to bacterial activity in hypersaline environments

Antibiotics affecting protein synthesis were used to differentiate between the activity of different groups of organisms (halophilic archaebacteria, eubacteria and eukaryotes) in water samples from hypersaline ecosystems. Anisomycin (inhibiting both archaebacterial halophiles and eukaryotes) can be used to quantitate the contribution of the archaebacterial halophiles to amino acid incorporation by the microbial community, when cycloheximide (inhibiting eukaryotic protein synthesis, but not affecting halobacteria) is used as a control. Both in saltern ponds at salinities above 300 g/1 and in Dead Sea surface water more than 95% of the amino acid incorporation activity was abolished by anisomycin, but not by cycloheximide. Inhibition by anisomycin was well correlated with inhibition by low concentrations of bile salts, which specifically affect bacteria of the Halobacterium group. Chloramphenicol (an inhibitor of eubacterial protein synthesis) quantitatively inhibited amino acid incorporation in saltern brines of relatively low salinity, but also caused significant (28–42%) inhibition at high salinities. Erythromycin was also found valuable in the estimation of activities of the different bacterial groups.

Association of Neutrophil Alkaline Phosphatase Activity and Glycosylated Haemoglobin in Diabetes mellitus

We determined neutrophil alkaline phosphatase (NAP) activity in diabetic patients in conjunction with HbA1c levels. NAP was estimated using semiquantitative cytochemical technique, and we studied its activity in different groups of diabetic patients. We found that NAP score is correlated with the HbA1c level. Non-diabetic patients were used as controls, in whom NAP score and HbA1c were found normal. In diabetic patients the NAP activity and the HbA1c level were altered similarly during the various phases of the disease. Our findings indicate that NAP score could be used as a simple new parameter for diabetes. The pathophysiologic mechanism of our observations needs further investigation.

Pattern of tonic activity in different groups of rabbit superior cervical ganglion neurons

Tonic activity in rabbit superior cervical ganglion neurons was investigated using intracellular recording techniques as well as changes produced when the animal breathed a gaseous mix with a raised CO2 level. The test neurons were divided into three groups depending on the pattern of their tonic activity and reflex change. Action potentials were produced by the activity of dominant and accessory preganglionic inputs in the firing pattern of all neuronal groups, implying the existence of other types of inputs into the neurons innervating different organs. Having analyzed changes in action potential rate and EPSP in the tonic activity of neurons from different groups, it was presumed that preganglionic fibers with a similar activity pattern converge on the majority of neurons in each group.

Public policies, pressure groups, and dead weight costs

This paper presents a model of competition among special interest groups for political influence. Each active group exerts pressure to affect its taxes and subsidies, where activities of different groups are related by the equality between total tax collections and total tax subsidies. The dead weight costs and benefits of taxes and subsidies play a major role in our model. An increase in the dead weight cost of taxation encourages pressure by taxpayers, while an increase in the dead weight costs of subsidies discourages pressure by recipients. Various applications of the analysis are discussed.

Activity patterns of aminoacyl-tRNA synthetases, tRNA methylases, arginyltransferase and tubulin: tyrosine ligase during development and ageing of Caenorhabditis elegans.

As a step in the characterization of development and ageing in the nematode Caenorhabditis elegans, the activities of different groups of enzymes that supposedly exert modulating functions in and after protein synthesis have been determined. From embryonic (E), the four juvenile larval stages (L1-L4) and the gravid adult (A,A+), the selection of defined developmental stages extends to two different preparations of aged nematodes (S10, S12). Some aminoacyl-tRNA synthetase activities remain nearly unchanged in all stages up to the adult, some increase continuously during the larval stages and the remaining activities show stage-specific alterations. Upon ageing all activities except the one for tryptophan decrease sharply, tRNA methylase activities increase from E to L4, decrease from L4 to adult and to aged nematodes with only qualitative alterations in substrate specificity. The activity of tubulin: tyrosine ligase exhibits a parallel pattern, while arginyltransferase activity has a plateau between L2 and L4. The results are consistent with the idea of a modulation of protein synthesis and other cellular processes by quantitative activity changes during development and ageing.

Pyruvate Pi dikinase activity in different groups of crassulacean acid metabolism plants

The levels of pyruvate Pi dikinase, NADP malic enzyme, NAD malic enzyme and phosphoenolpyruvate (PEP) carboxykinase were estimated in ten Crassulacean acid metabolism (CAM) plants. Species utilizing NADP malic enzyme and NAD malic enzyme to decarboxylate malate possessed more pyruvate Pi dikinase and this enzyme was minimal in species utilizing PEP carboxykinase for decarboxylation. The regulatory role of this enzyme in CAM plants with different decarboxylating systems was discussed.

Structure-activity relationships of non-steroid anti-inflammatory drug 1. Gastric ulcerogenic activity.

A comparison was performed of structure with gastric ulcerogenic activity of a range of acidic and one group of non-acidic (tetrazine) non-steroid anti-inflammatory (NSAI) drugs with the object of establishing the physico-chemical properties of these drugs involved in gastric ulceration. The results with non-acetylated salicylate analogues show that an increase in lipophilic properties of 3-substituted salicylates was associated with decreased gastric ulceration. The converse was, however, observed with 4- and 5-substituted salicylates, i.e. increased lipid solubility was associated with enhanced gastric ulceration. 0-Acetylation increased the ulcerogenic activity of all salicylates (except 4-t-butyl derivative). Lipid solubility was also found to influence the gastric ulcerogenic activity of other NSAI drugs in different ways. It is also apparent that electronic factors (which reflect changes in the dissociation constants) and the position of electron-withdrawing substituents on aromatic groups variously influences the ulcerogenic activity in different groups of NSAI drugs. The presence of the carboxylic acid moiety is a major factor in ulcerogenesis by acidic NSAI drugs. Laser Raman spectroscopy of these drugs shows that there is a profound alteration in the frequency of absorption of the carbonyl group in the solid state and in concentrated solutions at pH 6–7. Such changes reflect an intermolecular interaction between the carbonyl and hydroxyl groups of carboxylic acids and suggest that these drugs exist as dimers under these conditions. Dimeric NSAI drugs may initiate gastric damage by the breaking of bonds between the dimers and reformation of bonds between the drugs and membrane phospholipids so disrupting the latter and leading to permeability changes.

Analysis of temporal relations among units and slow waves in rabbit hippocampus

BERRY, S. D., P. C. RINALDI, R. F. THOMPSON AND M. VERZEANO. Analysis of temporal relations among units and slow waves in rabbit hippocampus. BRAIN RES. BULL. 3(5) 509–518, 1978.—Arrays of triple microelectrodes were stereotaxically lowered into CA1, CA3 and dentate areas of the dorsal hippocampal formation in anesthetized rabbits. Recordings of action potentials and waves were analyzed on a PDP-11 computer using auto-, cross-, and multiplecorrelation programs to determine temporal relations during 90 sec samples of spontaneous activity. It was found that temporal periods of neuronal firing and inhibition were strongly related to the pattern of waves. During periods of high amplitude synchronous waves (theta), the correlation between the activities of different groups of neurons was directly related to the periodicity of the wave. During instances of lower amplitude, desynchronous wave activity, the correlations between spikes recorded from those same cells were less periodic, varying according to the amount of wave synchrony. Variations in wave synchrony due to anatomical location, eserine effects, or spontaneous fluctuations under anesthesia produced corresponding variations in the relations between the activities of different groups of neurons. It is suggested that these relations between neuronal activity and gross waves may be implicated in processes which are at the basis of learning and memory.

Messages conveyed by spinocerebellar pathways during scratching in the cat. II. Activity of neurons of the ventral spinocerebellar tract

(1) The activity of neurons of the ventral spinocerebellar tract (VSCT) during scratching was studied in thalamic and decapitate cats. The neurons were identified antidromically either by stimulation of the hindlimb area in the anterior lobe of the cerebellum (in thalamic cats) or by stimulation of the contralateral ventrolateral funiculus of the spinal cord (in decapitate cats). The scratch reflex was elicited by stimulation of either the pinna (in thalamic cats) or the cervical spinal cord (in decapitate cats). In most experiments, animals were immobilized and the activity of VSCT neurons was recorded during fictitious scratching 13. (2) During both actual and fictitious scratching, the discharge of VSCT neurons was rhythmically modulated in relation with the scratch cycle: neurons fired in bursts separated with periods of silence. Phases of activity of different neurons were unevenly distributed over the scratch cycle: most neurons fired within the limits of the flexor phase of the cycle. (3) The firing pattern of VSCT neurons during fictitious scratching was similar to that during actual scratching. Therefore, rhythmical burst firing of VSCT neurons is determined mainly by central mechanisms and not by a rhythmical sensory input. (4) The firing pattern of VSCT neurons in decapitate cats was similar to that in thalamic cats. Therefore, rhythmical burst firing of VSCT neurons is determined mainly by the central spinal mechanism and not by supraspinal motor centers. (5) The VSCT neurons which fired in long bursts during the greater part of the flexor phase were usually activated during the latent period of scratching, while those firing later in the cycle were usually either inhibited or not affected during this period. (6) The antidromic response in most VSCT neurons could be evoked from a large number of points in the hindlimb area of the cerebellar anterior lobe, both in the vermis and in the pars intermedia. Due to such extensive branching of axons, each point of the cortex receives signals from neurons firing in different phases of the cycle. But axons of VSCT neurons firing in long bursts during the greater part of the flexor phase terminate more extensively in the pars intermedia, while axons of neurons firing later in the cycle terminate more extensively in the vermis. (7) The functoning of the VSCT is essentially similar to that of the spinoreticulocerebellar pathway (SRCP) 5. Both pathways convey messages about activity of the central spinal mechanism generating the motor output pattern of scratching, but the VSCT is active mainly in the flexor phase of the scratch cycle and the SRCP in the extensor one. A hypothesis is advanced that these pathways monitor activity of different groups of spinal interneurons.

Afferent impulses in cat vagus nerve fibers studied by coincidence of recorded action potentials

Tonic electrical activity of different groups of afferent fibers of the intact vagus nerve arising in stretch receptors of the lungs was investigated in acute experiments on cats. The method of coincidence of recorded action potentials was used: Recordings were taken from two points of the nerve, the flow of impulses was delayed by the time taken for their conduction along the nerve between the channels in the one that received it first, and impulses from both channels were then led to a coincidence unit. Fibers with a range of conduction velocities from 8 to 65 m/sec were shown to participate in the transmission of tonic activity from stretch receptors of the lungs to the CNS. Two groups of most active afferent fibers with conduction velocities within the range 35–46 m/sec (mean 41±2.5 m/sec) and 26–34 m/sec (mean 29.4±1.4 m/sec) were distinguished.

Electromyographic studies of tremor using an averaging computer

Tremor has been studied by summing electromyographic signals in an averaging computer. Such analyses afford precise comparison of the mean patterns of activity in different groups of muscles. Complex movements such as “pill-rolling” involve synchronous excitation of certain muscles in the flexor and extensor compartments ( e.g., flexor pollicis longus and extensor digitorum) but this does not indicate a disturbance in motor control. In patients with generalized tremor, independent frequencies were present in different limbs, and sometimes in different segments of the same limb. Regularity varied from one limb to another. Changes in posture of a limb produced alteration in the frequency, and occasionally in the phase relationships, of activities in different muscles.

Measurement of lipoprotein lipase activity in post heparin plasma: description of technique

A method has been described for the quantitative assay of lipoprotein lipase activity in post heparin plasma. The conditions of the assay were subjected to critical study. The technique described permits the reaction to proceed in the test tube as a zero order reaction. It is believed that this technique will permit accurate quantitative study of lipoprotein lipase activity in different groups of patients. The rate of lipolysis was compared with the rate of clearing of lipemic plasma. The ratio of the rate of lipolysis to the rate of clearing was quite variable in normal subjects. This suggests that the use of the clearing technique to study lipoprotein lipase activity in different groups of patients, or under different experimental conditions, may give misleading results.