Alterations in cerebrospinal fluid uridine,hypoxanthine, and xanthine in head-injured patients

1. Examination of the cerebrospinal fluid (CSF) of head-injured patients reveals that the concentration of intraventricular xanthine is elevated and that of uridine is decreased relative to those of adult lumbar CSF. 2. No correlations were observed between CSF lactate and CSF hypoxanthine, xanthine, or uridine, suggesting that changes in purine metabolites and the pyrimidine nucleoside do not index similar cellular events as does lactic acid production. 3. Ventricular CSF from hydrocephalic infants had uridine and hypoxanthine concentrations not significantly different from those of normal adult lumbar CSF, but xanthine was significantly elevated. 4. Since uridine has anticonvulsant properties and is a crucial substrate for cerebral metabolism, it may be useful to evaluate this pyrimidine for use in the management of patients with head injury.     

Changes in trace reactions of sensorimotor cortex and putamen neurons as affected by haloperidol

Experiments on conscious rabbits were made to elaborate motor conditioned reflexes through pairing stimuli with electrocutaneous reinforcement applied every 30 s. Neuronal activity in the sensorimotor cortex and putamen was recorded during formation and reproduction of the conditioned reflexes before and after haloperidol injection (0.2 mg/kg i. v.). In the putamen, haloperidol increased the number of neurons exhibiting trace conditioned activity and made the intensity and duration of these processes rise. The changes seen in the sensorimotor cortex were opposite in nature. Inhibition of trace conditioned activity in the sensorimotor cortex depended mainly on the decreased amplitude of the reaction conditioned component. The role of the dopaminergic system in the interaction of the neostriatum and sensorimotor cortex and in formation and reproduction of trace conditioned activity of both the structures is discussed.     

Transcriptional control, translation and function of the products of the five open reading frames of the Escherichia coli nir operon

Five open reading frames designated nirB, nirD, nirE, nirC and cysG have been identified from the DNA sequence of the Escherichia coli nir operon. Complementation experiments established that the NirB, NirD and CysG polypeptides are essential and sufficient for NADH-dependent nitrite reductase activity (EC 1.6.6.4). A series of plasmids has been constructed in which each of the open reading frames has been fused in-phase with the beta-galactosidase gene, lacZ. Rates of beta-galactosidase synthesis during growth in different media revealed that nirB, -D, -E and -C are transcribed from the FNR-dependent promoter, p-nirB, located just upstream of the nirB gene: expression is co-ordinately repressed by oxygen and induced during anaerobic growth. Although the nirB, -D and -C open reading frames are translated into protein, no translation of nirE mRNA was detected. The cysG gene product is expressed from both p-nirB and a second, FNR-independent promoter, p-cysG, located within the nirC gene. No NADH-dependent nitrite reductase activity was detected in extracts from bacteria lacking either NirB or NirD, but a mixture of the two was as active as an extract from wild-type bacteria. Reconstitution of enzyme activity in vitro required stoichiometric quantities of NirB and NirD and was rapid and independent of the temperature during mixing. NirD remained associated with NirB during the initial stages of purification of the active enzyme, suggesting that NirD is a second structural subunit of the enzyme.     

Changes in the properties of adenylate cyclase from guinea pig lungs in tuberculosis

Changes in the properties of adenylate cyclase from the lungs of tuberculotic guinea pigs were revealed. The number of beta-adrenergic receptors in the lungs was found to be reduced by 30% at the second and by 70% at the third stage of the disease. The degree and the value of Ka for adenylate cyclase activation by isoproterenol remained thereby unchanged. The basal activity of adenylate cyclase was increased by 20% against the control level at the second stage and decreased by 20% at the third stage of the disease. At these periods, the stimulating effects of guanylyl imidodiphosphate, NaF and forskolin on lung adenylate cyclase were diminished. The experimental results point to the significant role of the enzymes of cAMP metabolism and reflect the course of the tuberculosis process in experimental animals.     

Obtaining monoclonal antibodies to Bordetella pertussis antigens

The immunization of mice with the protein fraction of B. pertussis strain 305 has made it possible to obtain hybridomas producing monoclonal antibodies to B. pertussis antigens. Ascitic fluids containing monoclonal antibodies react in the ELISA in high titers and actively agglutinate B. pertussis strains 305 and 475.