The effect of hydroxyurea and mitomycin C on sperm motility in mice

The mutagen, mitomycin C, and the teratogen, hydroxyurea, were found to decrease sperm motility in mice in a dose-dependent manner. Positive results with these compounds suggest that sperm motility may have been decreased through either mutations or developmental disturbances. Sperm motility can be determined quickly and may be done in conjunction with a sperm-morphology assay.     

Isolation of a full-length mitotic cyclin cDNA clone CycIIIMs from Medicago sativa: Chromosomal mapping and expression

Cyclins in association with the protein kinase p34^cdc2and related cyclin-dependent protein kinases (cdks) are key regulatory elements in controlling the cell division cycle. Here, we describe the identification and characterization of a full-length cDNA clone of alfalfa mitotic cyclin, termed CycIIIMs. Computer analysis of known plant cyclin gene sequences revealed that this cyclin belongs to the same structural group as the other known partial alfalfa cyclin sequences. Genetic segregation analysis based on DNA-DNA hybridization data showed that the CycIIIMs gene(s) locates in a single chromosomal region on linkage group 5 of the alfalfa genetic map between RFLP markers UO89A and CG13. The assignment of this cyclin to the mitotic cyclin class was based on its cDNA-derived sequence and its differential expression during G2/M cell cycle phase transition of a partially synchronized alfalfa cell culture. Sequence analysis indicated common motifs with both the A- and B-types of mitotic cyclins similarly to the newly described B3-type of animal cyclins.     

Construction of a basic genetic map for alfalfa using RFLP, RAPD, isozyme and morphological markers

The genetic map for alfalfa presented here has eight linkage groups representing the haploid chromosome set of the Medicago species. The genetic map was constructed by ordering the linkage values of 89 RFLP, RAPD, isozyme and morphological markers collected from a segregating population of 138 individuals. The segregating population is self-mated progeny of an F1 hybrid plant deriving from a cross between the diploid (2n=2x=16) yellow-flowered Medicago sativa ssp. quasifalcata and the diploid (2n=2x=16) blue-flowered M. sativa ssp. coerulea. The inheritance of many traits displayed distorted segregation, indicating the presence of lethal loci in the heterozygotic parent plants. In spite of the lack of uniform segregation, linkage groups could be assigned and the order of the markers spanning > 659 centimorgans could be unambiguously determined. This value and the calculated haploid genome size for Medicago (1n=1x=1.0 x 10⁹ bp) gives a ratio of < 1500 kb per centimorgan.     

Dose-dependent dual effect of corticosterone on cerebral 5-HT metabolism

The action of 1.0 and 10.0 mg/kg (i.p.) of corticosterone on serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) contents and on serotonin turnover, measured by an MAO-inhibitor method, was studied at 30 and 120 min after administration. A 1.0 mg/kg dose of corticosterone increased the serotonin content and turnover in the hypothalamus and mesencephalon 30 min after administration; however, it was ineffective on dorsal hippocampus and frontal and parietal cortex. 5-HIAA content did not change significantly in any of the brain areas studied. A 10.0 mg/kg dose of corticosterone decreased the serotonin content and turnover in the hypothalamus and mesencephalon; it was ineffective in other brain areas investigated. 5-HIAA content significantly decreased in the hypothalamus while it increased in the mesencephalon and dorsal hippocampus. In the parietal and frontal cortex, 5-HIAA content did not change following administration of 10.0 mg/kg of corticosterone. At 120 min after corticosterone administration, neither 5-HT content and turnover nor 5-HIAA content showed any change in the brain areas investigated. The results suggest that corticosteroids might change the activity of the brain serotoninergic system in a dose- and time-dependent manner, and in this way the serotoninergic system might play an important role in mediation of the corticosteroid effect exerted on brain function.     

The synthesis of 13α-androsta-5,16-diene derivatives with carboxylic acid,ester and carboxamido functionalities at position-17 via palladium-catalyzed carbonylation

17-Alkoxycarbonyl- and 17-carboxamido-3β-hydroxy-13α-androsta-5,16-diene derivatives were synthetized in high yields in the palladium-catalyzed carbonylation reactions of the corresponding 3β-hydroxy-17-iodo-13α-androsta-5,16-diene. This substrate with a 17-iodo-16-ene functionality was obtained from the 17-keto derivative via its 17-hydrazone, which was treated with iodine in the presence of a base (1,1,3,3-tetramethylguanidine). 17-Carboxamides were obtained by chemoselective aminocarbonylation through the use of amines, including amino acid esters, as N-nucleophiles. The 17-methoxycarbonyl-16-ene derivative was synthetized by using methanol as O-nucleophile. The parent compound of this series, the 17-carboxylic acid derivative, was formed in the presence of water via hydroxycarbonylation.     

Brain phagocytes may empty tissue debris into capillaries

The possibility that brain phagocytes may empty remnants of degenerated neurons into capillaries has been studied in frogs. Degeneration of nerve fibers was brought about by transectioning the optic tract, the tectothalamic and tectoisthmic tracts, the postoptic commissure or the radial nerve. To help identification of phagocytozed degenerated neuronal elements, the transected fibers were filled either with horseradish peroxidase (HRP) or cobaltous-lysine complex. The survival times were 3, 4, 7, 27, 47 and 70 days after the application of the markers. The HRP-labeled structures were identified in 60 μm thick sections using diaminobenzidine as chromogen, while cobalt was precipitated in the form of cobaltous sulfide. Small pieces of these sections were further processed for electron microscopy. In each area of the brain and spinal cord investigated, microglial cells and astrocytic processes containing fragments of degenerated neuronal elements could be seen close to capillaries. In some cases a microglial or astrocytic process pierced the capillary basal lamina and seemingly delivered inclusion bodies into the cytoplasm of capillary endothelial cells and pericytes. In the inclusion bodies, which were usually large vesicles, fragments of HRP or cobalt-labeled or unlabeled membranes with a foamy appearance, or condensed myelin lamellae could be observed. These vesicles protruded the luminal membrane of the endothelial cell that was disrupted in some cases suggesting that the content of the inclusion body was discharged into the lumen of the capillary. These results give support to Penfield's hypothesis (1925) that glial cells may empty phagocytozed materials into capillaries.     

2,3-benzodiazepine-type AMPA receptor antagonists and their neuroprotective effects

AMPA receptors are fast ligand-gated members of glutamate receptors in neuronal and many types of non-neuronal cells. The heterotetramer complexes are assembled from four subunits (GluR1-4) in region-, development- and function-selective patterns. Each subunit contains three extracellular domains (a large amino terminal domain, an agonist-binding domain and a transducer domain), and three transmembrane segments with a loop (pore forming domain), as well as the intracellular carboxy terminal tail (traffic and conductance regulatory domain). The binding of the agonist (excitatory amino acids and their derivatives) initiates conformational realignments, which transmit to the transducer domain and membrane spanning segments to gate the channel permeable to Na+, K+ and more or less to Ca2+. Several 2,3-benzodiazepines act as non-competitive antagonists of the AMPA receptor (termed also negative allosteric modulators), which are thought to bind to the transducer domains and inhibit channel gating. Analysing their effects in vitro, it has been possible to recognize a structure-activity relationship, and to describe the critical parts of the molecules involved in their action at AMPA receptors. Blockade of AMPA receptors can protect the brain from apoptotic and necrotic cell death by preventing neuronal excitotoxicity during pathophysiological activation of glutamatergic neurons. Animal experiments provided evidence for the potential usefulness of non-competitive AMPA antagonists in the treatment of human ischemic and neurodegenerative disorders including stroke, multiple sclerosis, Parkinson's disease, periventricular leukomalacia and motoneuron disease. 2,3-benzodiazepine AMPA antagonists can protect against seizures, decrease levodopa-induced dyskinesia in animal models of Parkinson's disease demonstrating their utility for the treatment of a variety of CNS disorders.     

The expression of cholinesterases in human renal tumours varies according to their histological types

The change in the expression of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities in neoplastic colon and lung prompted us to study the possible effect of cancer on the expression of cholinesterases (ChEs) in kidney. Samples of papillary renal cell carcinoma (pRCC), conventional RCC (cRCC), chromophobe RCC (chRCC) and renal oncocytoma (RON), beside adjacent non-cancerous tissues, were analyzed. In pRCC both AChE and BuChE activities were statistically increased; in cRCC and chRCC only AChE activity increased and in RON neither AChE nor BuChE activities were affected. Abundant amphiphilic AChE dimers (G(2)(A)) and fewer monomers (G(1)(A)) were identified in healthy kidney as well as in all tumour classes. Incubation with PIPLC revealed glycosylphosphatidylinositol in AChE forms. BuChE is distributed between principal G(4)(H), fewer G(1)(H), and much fewer G(4)(A) and G(1)(A) species. RT-PCR showed similar amounts of AChE-H, AChE-T and BuChE mRNAs in healthy kidney. Their levels increased in pRCC but not in the other tumour types. The data support the idea that, as in lung tumours, in renal carcinomas expression of ChE mRNAs, biosynthesis of molecular components and level of enzyme activity change according to the specific kind of cell from which tumours arise.     

Atropine-induced gastrointestinal cytoprotection dependences to the intact of vagal nerve against indomethacin-induced gastrointestinal mucosal and microvascular damage in rats

The non-steroidal antiinflammatory drugs, such as an indomethacin (IND), cause mucosal ulceration and increase the mucosal vascular permeability in the gastrointestinal (GI) tract. Some exogenous agents, e.g. the atropine, can protect the GI mucosa against these ulcerogenic effects. The gastrointestinal functions and mucosal protection, however, are regulated by the vagal nerve. The aims of this study was to examine the dependence of atropine-induced GI cytoprotection to the vagal innervation against the development of IND-caused ulcers and microvascular damage in the mucosa of stomach and small intestine in rats. METHODS: the observations were carried out on CFY-strain rats. The mucosal damage was produced by subcutaneous administration of IND in a 20 mg/kg dose 24 h prior to the killing of animals at the same time as the start of atropine-application, which was given in a small dose (0.1 mg/kg) every 5 h. The subdiaphragmatic bilateral surgical vagotomy was done 24 h before the experiment. The vascular permeability, indicated by the microvascular endothel damage, was measured by the appearance and concentration of intravenously administered Evans blue into the GI mucosa. The number and severity of mucosal lesions and the Evans blue content of mucosa were determined in the stomach and small intestine. RESULTS: (1) The IND caused mucosal ulcers and Evans blue extravasation into the mucosa of the stomach and small intestine. (2) The IND-induced mucosal ulceration and vascular permeability significantly decreased after atropine-administration in the same parts of GI tract. (3) The extent of cytoprotective effect of atropine against the IND was decreased after bilateral surgical vagotomy. CONCLUSIONS: (1) The IND causes microvascular endothel damage in the stomach and small intestinal. (2) The atropine has a cytoprotective effect in the stomach and small intestine against the aggressive effects of IND without decrease of gastric acid secretion. (3) The intact vagal nerve is necessary to the function of cytoprotective mechanisms of atropine against the IND.     

The effect of etodolac on bile salt and histamine-mediated gastric mucosal injury in the rat

The effect of the selective cyclo-oxygenase-type-2 (COX-2) inhibitor etodolac on gastric mucosal integrity and gastric acid secretion was investigated in the rat. Etodolac was given in doses comparable with those being used in man for therapy of rheumatic conditions. The effect of etodolac was studied in the presence of a mild barrier breaker and in the presence of increased rates of endogenous acid secretion. In conscious pylorus-ligated rats, etodolac given intragastrically in 16 or 32 mg /kg for 3 h did not by itself give rise to visible gastric mucosal injury. Etodolac, however, exacerbated gastric mucosal injury evoked by intragastric application of acidified sodium taurocholate (5 mM in 150 mM HCl) in a dose-dependent manner. This effect of edotolac was independent of changes in gastric acid secretory responses. In rats whose gastric acid secretion was stimulated by intraperitoneal histamine (5 mg/kg), and etodolac (given i.g. in doses of 16 or 32 mg/kg) also increased gastric mucosal injury caused by histamine dose-dependently in the 3-h pylorus-ligated rats. Etodolac decreased gastric mucus in the saline- and in the sodium taurocholate-treated rats. In urethane-anaesthetized acute gastric fistula rats, intragastric etodolac (32 mg/kg) did not modify basal gastric acid secretion. Our data suggest that etodolac, a selective COX-2 inhibitor, impairs gastric mucosal resistance and can exacerbate gastric mucosal injury caused by other mucosal barrier breaking agents. Cyclooxygenase type-2 thus contributes to the gastric mucosal defences.