Saccade-related omnivectoral pause neurons in the primate zona incerta

The zona incerta contains GABAergic neurons projecting directly on to collicular efferent neurons. This study examined the physiological characteristics of incertal neurons and their relationship to saccades. Cells in the zona incerta have moderate rates of activity and pause during saccades. These pauses begin prior to the start of saccades and activity resumes after the end of saccades in all directions and for all amplitudes. This perisaccadic pause is positively correlated with the duration of the saccade such that the longer the saccade is, the longer a pause is observed. These physiological data, in conjunction with anatomical observations, suggest that the zona incerta might normally function by inhibiting the superior colliculus and then by disinhibiting the superior colliculus for saccades.     

Characterization of the mutant visual pigment responsible for congenital night blindness: a biochemical and Fourier-transform infrared spectroscopy study

A mutation in the gene for the rod photoreceptor molecule rhodopsin causes congenital night blindness. The mutation results in a replacement of Gly90 by an aspartic acid residue. Two molecular mechanisms have been proposed to explain the physiology of affected rod cells. One involves constitutive activity of the G90D mutant opsin [Rao, V. R., Cohen, G. B., & Oprian, D. D. (1994) Nature 367, 639-642]. A second involves increased photoreceptor noise caused by thermal isomerization of the G90D pigment chromophore [Sieving, P. A., Richards, J. E., Naarendorp F., Bingham, E. L., Scott, K., & Alpern, M. (1995) Proc. Natl. Acad. Sci. U.S.A. 92, 880-884]. Based on existing models of rhodopsin and in vitro biochemical studies of site-directed mutants, it appears likely that Gly90 is in the immediate proximity of the Schiff base chromophore linkage. We have studied in detail the mutant pigments G90D and G90D/E113A using biochemical and Fourier-transform infrared (FTIR) spectroscopic methods. The photoproduct of mutant pigment G90D, which absorbs maximally at 468 nm and contains a protonated Schiff base linkage, can activate transducin. However, the active photoproduct decays rapidly to opsin and free all-trans-retinal. FTIR studies of mutant G90D show that the dark state of the pigment has several structural features of metarhodopsin II, the active form of rhodopsin. These include a protonated carboxylic acid group at position Glu113 and increased hydrogen-bond strength of Asp83. Additional results, which relate to the structure of the active G90D photoproduct, are also reported. Taken together, these results may be relevant to understanding the molecular mechanism of congenital night blindness caused by the G90D mutation in human rhodopsin.     

Zea systematics: ribosomal ITS evidence

Ribosomal internal transcribed spacer (ITS) sequences were used to evaluate the phylogenetics of Zea and Tripsacum. Maximum likelihood and polymorphism parsimony were used for phylogenetic reconstructions. Zea ITS nucleotide diversity was high compared to other plant species, but approximately equivalent to other maize loci. Coalescence of ITS alleles was rapid relative to other nuclear loci; however, there was still much diversity within populations. Zea and Tripsacum form a clade clearly differentiated from all other Poaceae. Four Zea ITS pseudogenes were identified by phylogenetic position and nucleotide composition. The phylogenetic position of Z. mays ssp. huehuetenangensis was clearly established as basal to the other Z. mays. The ITS phylogeny disfavored a Z. luxurians and Z. diploperennis clade, which conflicted with some previous studies. The introgression of Z. mays alleles into Z. perennis and Z. diploperennis was also established. The ITS data indicated a near contemporary divergence of domesticated maize and its two closest wild relatives.     

The relation between serum markers in the second trimester and placental pathology. A study on extremely small for gestational age fetuses

To disclose the cytoprotective mechanism of 1,6-dihydro-2[2-(2-methyoxypropoxy)anilino]-6-oxo-5-pyrimidinecarb oxylic acid (CAS 98772-05-5, MAR-99), the effect of this compound on the microvascular injury in gastric mucosa induced by 99.5% ethanol in rats was studied. In this experiment, it was found that the elevation of vascular permeability observed at the early state of ethanol-induced gastric mucosal injury was closely correlated with the combined action of histamine and slow reacting substance (leukotriene C4, LTC4). MAR-99 (0.3-10 mg/kg p.o.) prevented dose-dependently the increase in vascular permeability. Furthermore, MAR-99 (10 mg/kg p.o.) improved the decrease in the number of histamine containing cells and histamine content, and prevented the production of LTC4. These results suggest that MAR-99 exerts its anti-microvascular injury effect by regulating the release of histamine and the production of LTC4 in glandular stomach against ethanol, and this effect may contribute to the anti-lesion effect of this compound.     

Molecular cloning, sequencing, and expression of the 36 kDa protein present in pars planitis. Sequence homology with yeast nucleopore complex protein

PURPOSE: Patients with active pars planitis have increased levels of a 36 kDa protein (p-36) in their circulation. The current studies were undertaken to determine the primary structure of this protein. METHODS: A degenerate oligonucleotide probe based on the amino terminal sequence of p-36 was used to identify a clone from a human spleen cDNA library. The cDNA insert was subcloned into the EcoR1 site of pUC-19, and both strands were sequenced. Southern blot analysis was used to study the genomic hybridization pattern. p-36 cDNA was subcloned in a pSG5 expression vector, and the construct was used to transfect COS-7 cells. RESULTS: The cDNA sequence contained an open reading frame of 966 base pairs encoding a protein of 322 amino acids, an untranslated region of 322 base pairs, and 2693 base pairs at the 5' and 3' ends, respectively. The deduced amino acid sequence showed 96.8% identity with the carboxy-terminal region of a yeast nucleopore complex protein, nup 100. Southern blot analysis of human genomic DNA revealed a simple hybridization pattern. Transfection of p-36 cDNA in COS-7 cells resulted in the presence of p-36 mRNA and expression of protein. CONCLUSIONS: The 36 kDa protein (p-36) detected at increased levels in the blood of patients with active pars planitis was cloned from a human spleen cDNA library. Its deduced amino acid sequence is homologous with the carboxy-terminal region of a nucleopore complex protein. Thus, we refer to this protein as nup36.     

Headache in intracerebral hematomas

OBJECTIVES: We sought to describe the frequency and location of headache in intracerebral hematoma (ICH) and to analyze its clinical and CT predictors by means of multivariate analysis. BACKGROUND: Headache is more common in intracerebral hemorrhage than in ischemic stroke, and its frequency varies with hematoma location, but the pathophysiologic mechanisms of headache associated with ICH are not fully known. METHODS: We examined a cohort of 289 patients with ICH during a 14-month period in a university hospital. Clinical, including the presence and location of headache, and CT features were collected by two neurologists. RESULTS: One hundred and sixty-five (57%) patients with ICH had a headache at the onset of their stroke. Headache was more common in cerebellar and lobar hemorrhages than in deep ones (thalamic, caudate, capsuloputaminal, brainstem). Headache was also more common in women, patients younger than 70 years, those who vomited, and those with meningeal signs, a Glasgow Coma Scale score < 10, a hematoma volume > 10 ml or CT evidence of intraventricular or subarachnoid bleeding, moderate to severe hydrocephalus, or transtentorial herniation or midline shift. In multiple logistic regression analysis, only meningeal signs (odds ratio [OR] = 2.3), cerebellar or lobar location (OR = 2.1), transtentorial herniation (OR = 1.8), and female gender (OR = 1.6) were significant predictors of headache at the onset of ICH. CONCLUSIONS: Hematoma location, meningeal signs, and gender are more predictive of headache than hematoma volume, suggesting that headache is more often related to the activation of an anatomically distributed system in susceptible individuals and to subarachnoid bleeding than to intracranial hypertension.     

Purification of a mammalian homologue of Escherichia coli endonuclease III: identification of a bovine pyrimidine hydrate-thymine glycol DNAse/AP lyase by irreversible cross linking to a thymine glycol-containing oligoxynucleotide

We purified a homologue of the Escherichia coli DNA repair enzyme endo nuclease III 5000-fold from calf thymus which, like endonuclease III, demonstrates DNA-glycosylase activity against pyrimidine hydrates and thymine glycol and AP lyase activity (DNA strand cleavage at AP sites via beta-elimination). The functional similarity between the enzymes suggested a strategy for definitive identification of the bovine protein based on the nature of its enzyme-substrate (ES) intermediate. Prokaryotic DNA glycosylase/AP lyases function through N-acylimine (Schiff's base) ES intermediates which, upon chemical reduction to stable secondary amines, irreversibly cross link the enzyme to oligodeoxynucleotides containing substrate modified bases. We incubated endonuclease III with a 32P- labeled thymine glycol-containing oligodeoxynucleotide in the presence of NaCNBH3. This resulted in an increase in the apparent molecular weight of the enzyme by SDS-PAGE. Phosphorimaging confirmed irreversible cross linking between enzyme and DNA. Identical treatment of the most purified bovine enzyme fraction resulted in irreversible cross linking of the oligodeoxynucleotide to a predominant 31 kDa species. Amino acid analysis of the 31 kDa species revealed homology to the predicted amino acid sequence of a Caenorhabditis elegans 27.8 kDa protein which, in turn, has homology to endonuclease III. The translated amino acid sequences of two partial 3' cDNAs, from Homo sapiens and Rattus sp., also demonstrate homology to the C. elegans and bovine sequences suggesting a homologous family of endonuclease III-like DNA repair enzymes is present throughout phylogeny.