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C Kaur

Publications and source records attributed to C Kaur.

90 records · Page 5Linked to original sources
PubMed1989

Scanning electron microscopy of transitory subependymal cysts in the developing midbrain of postnatal rats.

Transitory cystic cavities, associated with the subependymal region of the aqueduct in the midbrain of postnatal rats aged 1-15 days, were studied by light and scanning electron microscopy. The walls of these cysts, as observed in scanning electron microscopy, were lined by a dense feltwork of nerve fibres. Two types of cells were identified in the cysts: smaller glioblasts and larger amoeboid microglial cells. The glioblasts were characterized by a smoother cell body with radiating long processes. The amoeboid microglial cells showed blebs and pseudopodia on their surface. They either adhered to the walls or floated freely in the lumen. It is postulated that the formation of the subependymal cysts in the developing brain resulted following the cleavage or breakdown of the nervous tissue due to the expansion of the aqueduct and the brain as a whole. The amoeboid microglial cells in the cysts were probably derived from the extravasated blood monocytes in response to the physical damage ensuing during the formation of the cysts.

Animals↗
PubMed1987

Localisation of thiamine pyrophosphatase in the amoeboid microglial cells in the brain of postnatal rats.

The activity of TPPase in amoeboid microglial cells has been studied in postnatal rats. When examined with the light microscope such cells in 1-10 days old rats perfused with 4% paraformaldehyde were round and showed a dark brown reaction in their cytoplasm. In older rats (10-30 days), the reactive amoeboid microglial cells were oval, flattened or branched. Electron microscopic examination revealed that the reaction product was seen on the plasma membrane, in the subplasmalemmal vacuoles, in tubular invaginations of plasma membrane and in the transface of the Golgi saccules. In rats perfused with the mixed aldehyde solution, the amoeboid microglial cells did not show a positive TPPase reaction with the light microscope but at the ultrastructural level a weak reaction was seen in some cytoplasmic vacuoles and in the Golgi saccules.

Animals↗
PubMed1987

Origin and fate of neural macrophages in a stab wound of the brain of the young rat.

Colloidal carbon was injected intravenously into young rats to label circulating monocytes before making a stab wound in the brain. The rats were killed 3-16 days after the stab wound. Demonstration of non-specific esterase, thiamine pyrophosphatase and 5'-nucleotidase was carried out on the carbon-labelled macrophages at the site of lesion at various survival times. In rats killed 3-5 days after the injury numerous carbon-labelled macrophages were present in the needle passage as well as in the marginal area of the lesion and they showed a positive reaction for non-specific esterase. The reaction of the enzyme was found in some of the dense bodies in the form of punctate precipitates. The reaction for thiamine pyrophosphatase was seen in the Golgi saccules as well as on the plasma membrane, although in the latter the reaction was weaker. Intense reaction for 5'-nucleotidase was localised over the plasma membrane as well as over the dense bodies. The carbon-labelled macrophages displaying the activities of the above enzymes in the 3-5 days postoperative group were of the round type. However, in the 8-16 postoperative days animals, the cells were either oval or had assumed an elongated outline resembling the microglial cells seen in the tissue taken from the normal side. It is concluded that circulating monocytes are a main source of brain macrophage in traumatic brain lesions. In the healing process of the wound some of the cells regress to become microglial cells as shown by the presence of the carbon particles as well as non-specific esterase, thiamine pyrophosphatase and 5'-nucleotidase activity in the various stages of structural transformation.

Animals↗
PubMed1986

Labelling of amoeboid microglial cells in rats of various ages following an intravenous injection of horseradish peroxidase.

The macrophagic amoeboid microglial cells in the corpus callosum of postnatal rats were labelled following an intravenous injection of horseradish peroxidase (HRP). The earliest time when these cells were labelled was 3 h after the injection of HRP in postnatal (1-10 days) rats. Similar cells around the mesencephalic aqueduct and the fourth ventricle were also labelled. These cells, however, were weakly labelled in developing (11-20 days) and unlabelled in weaning (21-30 days) rats. The results suggest that in the postnatal rats, the HRP passed through the endothelial lining of the blood vessels and was then ingested by the amoeboid microglial cells. In the developing and older rats, the wall of blood vessels had developed fully thereby preventing the free passage of HRP into the brain tissues.

Aging↗
PubMed1985

Transformation of amoeboid microglial cells into microglia in the corpus callosum of the postnatal rat brain. An electron microscopical study.

An electron microscope study of the corpus callosum in postnatal rats of various ages was carried out to elucidate the fate of the amoeboid microglial cells. The cells present in the corpus callosum of younger rats (3-5 days) were round and showed an eccentric nucleus with marginal chromatin. They displayed numerous lysosomal granules and vacuoles in the cytoplasm. In older animals, i.e., from 7 days onwards some of the cells became oval so that by 15-20 days of age most of the cells were elongated and branched. In the latter, the cells showed a flattened or angular nucleus with dense chromatin clumps. The cytoplasm showed fewer lysosomal granules and vacuoles which were absent in cells of 20 day old animals. Quantitative measurements showed that there was a gradual diminution in the amount of cytoplasm at the cell body of amoeboid microglial cells with age, so that by the age of 20 days the cells were reduced to less than one-third of their original size as seen in 3 day old rats. The reduction of cytoplasm at the cell body is probably because it is channelled to the cytoplasmic processes which are evident in older rats. Some cytoplasm may have been extruded and phagocytosed by companion cell types.

Age Factors↗
PubMed1984

Cytochemical localisation of 5'-nucleotidase in amoeboid microglial cells in postnatal rats.

The activity of the enzyme 5'-nucleotidase has been studied in postnatal rats. In 5 days old rats, under the light microscope, round amoeboid microglial cells were stained for the enzyme. The cytoplasm was stained dark brown, with a clear nucleus. In older rats, the reactive amoeboid microglial cells assumed an oval or flattened form. In the electron microscope, in 5 days old rat, reaction product was deposited at various sites in the cytoplasm of the amoeboid microglial cells: over lysosomes in subplasmalemmal vacuoles as well as in saccules of the Golgi apparatus. In older rats the cells showed reaction over the lysosomes. The cells became oval and elongated.

5'-Nucleotidase↗
PubMed1983

An inhibitory role for morphine on the release of dopamine into hypophysial portal blood and on the synthesis of dopamine in tuberoinfundibular neurons.

The intracerebroventricular administration of morphine to ovariectomized rats resulted in a marked decrease in the concentration of dopamine in plasma of hypophysial portal blood. A 90% reduction in the rate of release of hypothalamic dopamine into hypophysial portal blood occurred during the 60 min following the intraventricular administration of 60 ng of morphine sulfate. A dose-related decrease in the rate of release of dopamine into the portal vasculature was observed between 7.5 ng and 60 ng of morphine sulfate. Regardless of the quantity of morphine sulfate (1-500 ng) given to the animals, the concentrations of norepinephrine and epinephrine in hypophysial portal plasma and femoral arterial plasma remained unchanged. The efficacy of morphine on the release of dopamine into hypophysial portal blood was not associated with an equal efficacy of the drug on the synthesis of dopamine in tuberoinfundibular neurons, as evaluated by the accumulation of dihydroxyphenylalanine (DOPA) in the median eminence of rats given 3-hydroxybenzylhydrazine (NSD 1015). No effect of morphine was observed on DOPA accumulation in the median eminence of NSD-treated rats that had received 50 ng of morphine sulfate intracerebroventricularly, and only a 50% reduction was observed in the accumulation of DOPA in the median eminence of rats given 500 ng of morphine sulfate. These findings are supportive of the view that morphine inhibits both the release and synthesis of dopamine but is more effective in inhibiting the release than synthesis of dopamine.

Animals↗
PubMed1981

Antiandrogenic effects of cyproterone acetate and chloromadinone acetate on the rat hypothalamus as revealed by electroencephalographic responses.

Bipolar stainless steel electrodes were implanted stereotaxically into given hypothalamic and cortical regions of the brain of 48 rats. The animals were divided into two groups of equal numbers and the electrical activity of the given regions was recorded electroencephalographically (EEG). The effect of the acute and chronic administration of cyproterone acetate (CPA) or chloromadinone acetate (CHA), in doses inducing sterility, on EEG activity were observed. Apart from slight inhibition in the preoptic region, no appreciable EEG changes were found after CPA, while CHA reduced the discharge frequency in both the preoptic and the posterior hypothalamus. These findings can be attributed to the presence of two different types of androgen receptors in the hypothalamus.

Androgen Antagonists↗
PubMed1979

Synchronization of EEG activity of male Rhesus monkeys Macaca mulatta treated with ovocyclin.

Bipolar stainless steel electrodes were stereotaxically implanted in hypothalamus and cortex of six male monkeys. The effect of intramuscular injection of estradiol dipropionate (ovocyclin) in a dose of 10 mg/d was observed on EEG activity on 3 successive days. On the first day, slow waves appeared only in preoptic and on the second day also in posterior hypothalamus. Generalized slowing with an increase in amplitude appeared in all the hypothalamic areas and cortex on the third day. This suggest estrogen to possess (i) cumulative effect on brain and (ii) inhibitory action in the form of synchronization of EEG activity.

Animals↗
PubMed1978

1,2-Propanediol-induced changes in plasma and tissue lipids of rats.

Oral administration of 1,2-propanediol to rats in a daily dose of 1 ml of 28.4% aqueous solution per 100 g body weight for 30 days caused a significant decrease in the total lipids, fatty acids, phospholipids, and triglycerides of plasma, liver, and heart. The cholesterol content in plasma decreased while that in the tissues increased significantly. The accumulation of cholesterol in tissues tends to discourage long term use of 1,2-propanediol even by the oral route.

Animals↗
PubMed1973

New colorimetric method for the quantitative estimation of phospholipids without acid digestion.

A unique colorimetric method for the quantitative determination of phospholipids that does not involve the acid digestion of the lipid is described. The phospholipids, after separation by thin-layer chromatography and elution from the silica gel, are heated with a chromogenic solution that is a modification of a spray reagent formulated by Vaskovsky and Kostetsky (1968, J. Lipid Res., 9: 396). The absorbance of the colored complex was read at 710 nm, and it followed Beer's law in the range of 1-10 micro g of phospholipid phosphorus.

Chromatography, Thin Layer↗
PubMedDate not supplied

Effects of estradiol dipropionate on the biochemical composition of testis and accessory sex organs of adult rats.

A short term treatment of 14 days with estradiol dipropionate, ovocyclin¿ to adult male albino rats for 7 and 14 days in a dose of 2 mg/rat significantly inhibited the structural and functional integrity of the testis and accessory glands. The weights of these organs were significantly reduced. The activity of the enzymes acid and alkaline phosphatase and succinic dehydrogenase in testis and the concentration of sialic acids, fructose and citric acid in caput and cauda epididymides, prostate and seminal vesicles respectively were significantly lowered after both treatments. All these changes were found to be irreversible even on withdrawal of ovocyclin¿ for 28 days after 14 days treatment. On discussing the results with previous reports, it is proposed that estrogens probably impede the activity of these organs by inhibition of androgen production, their antiandrogenic nature or their direct action on these organs.

Androgen Antagonists↗
PubMedDate not supplied

Enhancement of ovulation by luteinizing hormone in cyclic albino rats.

Treatment of cyclic albino rats with equine luteinizing hormone (LH) on the afternoon of proestrus significantly enhanced ovulatory capacity. The number of ova shed and the healthy corpora lutea in the ovaries were significantly increased. Ovarian proteolytic enzymes also increased significantly with LH treatment. The histologically normal graafian follicles bound to become atretic in the vehicle-treated animals were altogether absent in the LH-treated rats on the day of estrus. These results indicate that LH enhances the number of ovulations by reducing the preovulatory follicles from atresia and facilitates their rupture by increasing the amount of proteolytic enzymes in them. A single injection of porcine follicle stimulating hormone (FSH), human chorionic gonadotrophin (hCG), and pregnant mare's serum gonadotrophin (PMSG) given separately was ineffective in inducing superovulation in cyclic albino rats.

Animals↗