Substrate specificity of tRNA (adenine-1-)-methyltransferase from Thermus thermophilus HB27

tRNA (adenine-1-)-methyltransferase was purified to homogeneity from an extreme thermophile, Thermus thermophilus HB27, by several steps of column chromatographies. The molecular weight of this enzyme was about 60,000 as analyzed by SDS polyacrylamide gel electrophoresis. Km for E. coli tRNA(2Glu) was 100 nM and that for the methyl group donor, S-adenosyl-L-methionine, was 7.8 microM. The substrate specificity of the enzyme was investigated by using T7 RNA polymerase transcripts and tRNA fragments obtained by partial digestion with RNases. The enzyme was able to transfer the methyl group to the 3'-half fragment of E. coli initiator tRNA, however, the extent of methylation was elevated by more than five times when the 5'-half fragment was added and annealed to the 3'-half. This indicates that the main recognition site of the enzyme is within the 3'-half region of tRNA molecule, while the tertiary interaction between the T-loop and the D-loop is very effective for the adequate methylation reaction.

Responses of tonically active neurons in the primate's striatum undergo systematic changes during behavioral sensorimotor conditioning

The basal ganglia have been implicated in motor planning and motor learning. In the study reported here, we directly tested for response plasticity in striatal neurons of macaque monkeys undergoing Pavlovian conditioning. To focus the study, we recorded from the tonically active neurons (TANs) of the striatum, which are known to respond to conditioned sensory stimuli that signal reward delivery and elicit behavioral reactions. The activities of 858 TANs were recorded extracellularly from the striatum in alert behaving macaque monkeys before, during, and after the acquisition of a classical conditioning task. Two monkeys were trained to lick reward juice delivered on a spoon simultaneously with the presentation of a click. Almost no licks were triggered by the cues at the start of training, but by the fifth day more than 90% of licks were triggered, and values were near 100% for the remainder of the 3 week training period. In the striatum, only a small number of TANs responded to the clicks at the start before conditioning (about 17%). During training, the numbers of responding TANs gradually increased, so that by the end of training more than 50-70% of the TANs recorded (51.3-73.5%) became responsive to the clicks. The responses consisted of a pause in firing that occurred approximately 90 msec after the click and that was in some cells preceded by a brief activation and in most cells was followed by a rebound excitation. Prolonged recordings from single TANs (n = 6) showed that individual TANs can acquire a conditioned response within at least as short a time as 10 min. TANs retained such responsiveness after overtraining, and also after a 4 week intermission in training. When the monkey was trained to receive rewards in relation to a new conditioning stimulus, TANs were capable of switching their sensory response to the new stimulus. Histological reconstruction showed that the TANs that became responsive were broadly distributed in the region of striatum explored, which included the dorsal half to two-thirds of the caudate nucleus and putamen over a large anteroposterior span. We conclude that, during the acquisition of a sensorimotor association, TANs widely distributed through the striatum become responsive to sensory stimuli that induce conditioned behavior. This distributed change in activity could serve to modulate the activity of surrounding projection neurons in the striatum engaged in mediating learned behavior.

Establishment of the two glioma cell lines: YH and AM

We have established two human glioma cell lines, which were designated as YH cells and AM cells. The two cell lines have maintained morphological appearance as seen in the primary culture and immunohistochemically expressed glial fibrillary acidic protein (GFAP) and S-100 protein. Population doubling time for YH cells and AM cells indicated 30 hours and 25 hours, respectively, in an exponential phase of culture.

Effects of neopterin on ischemic neuronal damage in gerbils

The effects of neopterin on ischemic neuronal damage were examined. Cerebral ischemia was produced in the gerbil by bilateral common carotid occlusion for 8 min or unilateral occlusion for 30 min, which resulted in delayed neuronal death in the CA1 region of the hippocampus. However, preischemic treatment with neopterin (3 mg/kg i.p.) markedly reduced hippocampal neuronal damages in both cases. Since neopterin serves both as an antioxidant and as an oxidant depending on its redox state, these findings indicate that neopterin attenuates the ischemic neuronal injury by scavenging oxygen free radicals and/or by inhibiting their generation.

Structure-activity relationships in the induction of single-strand breakage in plasmid pBR322 DNA by amino sugars and derivatives

Structure-activity relationships in the induction of strand breakage in plasmid pBR322 DNA by amino sugars and their derivatives were investigated using agarose gel electrophoresis. The coexistence of a potential free aldehyde group at the C-1 position and a free amino group at the C-2 position in the molecules was indispensable for the display of DNA strand-breaking activity in both mono- and oligo-aminosaccharides. The activity was increased by the introduction of an acidic group, especially a phosphate group, at the C-6 position. The activity was also increased by the addition of Cu2+. The order of activity of the amino monosaccharides tested was D-isoglucosamine > D-mannosamine > D-galactosamine > D-glucosamine, and it is suggested that this order is correlated with the portion of acyclic (aldehydo) form in the solution of each sugar. The possible chemical basis for DNA strand breakage by amino sugars is discussed.

[Basic and clinical research in hydrocephalus]

Hydrocephalus is appointed as one of intractable diseases by the Ministry of Health and Welfare of Japan. The research committee on intractable hydrocephalus has proposed the definition, clinical classification and diagnostic criteria of hydrocephalus in the CT and MRI era. To establish the diagnosis of congenital hydrocephalus, we set up inclusion and exclusion criteria, in addition to supplements which are useful for its diagnosis. In this symposium, we will report and discuss the results obtained so far in the research committee.

Rat CINC/gro: a novel mediator for locomotive and secretagogue activation of neutrophils in vivo

The effects of rat CINC/gro, a member of the interleukin-8 family, on the endothelium-neutrophil interaction and transendothelial macromolecular leakage were studied in rat mesenteric microcirculation. Thirty minutes after superfusion with 10 nM CINC/gro, the number of neutrophils adherent to the venular endothelium and those migrated across the venules were significantly increased with a concomitant elevation of luminol-dependent chemiluminescence at the site of adhesion. Transendothelial macromolecular leakage as assessed by the relative length of venular wall stained with monastral blue B was also increased at 30 min after the start of CINC/gro superfusion. Pretreatments with a CD18-directed monoclonal antibody, WT-3 (1 mg/kg), significantly attenuated the increase in number of adherent and migrated neutrophils, the increase in luminol-dependent chemiluminescence, and the venular macromolecular leakage after the application of CINC/gro. These data suggest that CINC/gro is a novel stimulator that evokes not only locomotive but also secretagogue activation of neutrophils via a CD18-dependent mechanism in vivo.

Construction and characterization of a fimA mutant of Porphyromonas gingivalis

Although fimbriae of Porphyromonas gingivalis have been implicated as playing a major role in adherence to gingival tissue surfaces, no conclusive genetic evidence has yet been obtained. The fimA gene, the determinant for the major fimbrial subunit protein, was cloned and sequenced (D. P. Dickinson, M. A. Kubiniec, F. Yoshimura, and R. J. Genco, J. Bacteriol. 170:1658-1665, 1988). We undertook to inactivate the fimA gene by a homologous recombination technique and examined the fimA mutant for changes in surface properties, including production of fimbriae, adherence to human gingival fibroblasts and epithelial cells, hemagglutinating activity, and surface hydrophobicity. To inactivate the fimA gene, we disrupted a fimA clone by insertion of a DNA segment containing an erythromycin resistance (Emr) gene. This was then delivered into P. gingivalis ATCC 33277 from an Escherichia coli K-12 strain, SM10 lambda pir, by using a mobilizable suicide vector, pGP704; recombination at the fimA locus led to the isolation of a fimA mutant. Disruption of the fimA locus and disappearance of FimA production were confirmed by Southern hybridization with a fimA-specific DNA probe and Western immunoblotting with a monoclonal antibody against the FimA protein, respectively. The fimA mutant constructed failed to express long (0.5- to 1.0-micron) fimbriae from the bacterial surface and had a diminished adhesive capacity to tissue-cultured human gingival fibroblasts and epithelial cells. Observation of the bacteria adhering to human gingival fibroblasts by scanning electron microscopy revealed that the wild-type strain had dramatic local changes in the appearance of the microvilli at the point of contact with large bacterial clumps, whereas the fimA mutant did not. In contrast, neither the hemagglutinating activity nor the surface hydrophobicity was changed in the fimA mutant. These data thus constitute the first direct genetic evidence demonstrating that the FimA protein of P. gingivalis is essential for the interaction of the organism with human gingival tissue cells through a function(s) encoded by the fimA gene.

[A case of intracranial arteriovenous malformation presenting with intracranial hypertension]

A case of unruptured arteriovenous malformations (AVMs) presenting benign intracranial hypertension is reported. A 14-year-old male suffered from headache and papilledema. Intracranial pressure was 260 mmH2O. Unenhanced CT demonstrated no evidence of hemorrhage or hydrocephalus. Angiogram demonstrated a large AVM in the left temporal lobe supplied by the left posterior cerebral artery and left middle cerebral artery. It drained into the transverse sinus. Surgical excision of the AVM eliminated the headache and papilledema. AVM causes hemorrhage in 50% of cases, seizure in 30%, and other focal neurological deficits in 20%. Benign intracranial hypertension is an uncommon effect of unruptured AVMs. Only 13 cases have been reported in the literature. Benign intracranial hypertension associated with unruptured AVMs occurs in young patients with high flow AVMs that drain into the major sinus. The mechanism of intracranial hypertension associated with unruptured AVM is unknown. However, there are several possible mechanisms of intracranial hypertension associated with unruptured AVMs. The arterial blood shunting into a major sinus impedes venous return from the surrounding brain. That causes the increase of cerebral blood volume and the elevation of sinus pressure. This mechanism would reduce CSF absorption and would increase intracranial pressure. Pharmacological therapy is ineffective in controlling intracranial hypertension. Surgical excision of AVM effectively reduced intracranial hypertension. Thus, surgical excision of AVMs, if it can be done with low risk, is the treatment of choice to decrease intracranial hypertension in patients with unruptured cerebral AVMs.

[Analysis of plasma amino acids-tryptophan and tyrosine ratios to other large neutral amino acids in manic-depressive illness]

On the basis of the hypothesis of the brain monoamine metabolism abnormality in manic-depressive illness, plasma tryptophan (TRP) ratio, an indicator of brain 5HT level, and the ratios of other neutral amino acids (tyrosine (TYR), valine, isoleucine, leucine, and phenylalanine) were determined in manic and depressed patients. Our results suggest that, in manic-depressive illness, there might be abnormalities in the metabolism of neutral amino acids, mainly of TRP and TYR, and that abnormality of TRP might be related to the depressive symptoms, and that plasma TRP and TYR ratios might be important indicators for determining the efficacy of some anti-manic and anti-depressive drugs.

[Clinico-epidemiologic study of infantile hydrocephalus in Japan]

A nation-wide survey on congenital hydrocephalus, including secondary hydrocephalus occurring within one year after birth, was carried out in 1988. The number of patients with congenital hydrocephalus treated during the previous one year was estimated to be 3,200-3,500 throughout Japan. The number of new cases of this disease which occurred during the year was calculated to be 800. This indicates a rate of 0.58 per 1,000 live births. Clinico-epidemiologic features were compared with regard to three subjects listed below. (1) The difference between the epidemiologic profile of term and preterm infants with hydrocephalus was investigated. As for etiology, the incidences of primary hydrocephalus and hydrocephalus complicated by Arnold-Chiari malformation type II and meningocele were significantly higher in term infants than in preterm infants. It was estimated that about 30% of the hydrocephalus in preterm infants and only 7.7% in term infants occurred as a consequence of intracranial hemorrhage. The degree of neurological impairment and the mortality rate were higher in preterm infants than term infants. (2) The changing panorama of infantile hydrocephalus in Japan was investigated comparing the epidemiologic data of four groups according to the birth year. As for pregnancy period, preterm infants with hydrocephalus were gradually increasing recently. Hydrocephalus secondary to intracranial hemorrhage was increasing and that secondary to intracranial infection was decreasing. The rate of shunt malfunction was decreasing significantly. (3) Clinico-epidemiologic features of intractable hydrocephalus based on the diagnostic criteria of the research committee was investigated comparing intractable with non-intractable groups.(ABSTRACT TRUNCATED AT 250 WORDS)

CT manifestations of intraspinal air associated with pneumomediastinum

Collections of air in the spinal canal have been observed in patients with spinal disorders, whereas intraspinal air secondary to pneumomediastinum is rare (6). This is a report of 2 patients with pneumomediastinum where collections of air were identified in the spinal canal on CT.

Cell adhesion molecules in inflammation and immunity: relevance to periodontal diseases

Inflammatory and immune responses involve close contact between different populations of cells. These adhesive interactions mediate migration of cells to sites of inflammation and the effector functions of cells within the lesions. Recently, there has been significant progress in understanding the molecular basis of these intercellular contacts. Blocking interactions between cell adhesion molecules and their ligands has successfully suppressed inflammatory reactions in a variety of animal models in vivo. The role of the host response in periodontal disease is receiving renewed attention, but little is known of the function of cell adhesion molecules in these diseases. In this review we summarize the structure, distribution, and function of cell adhesion molecules involved in inflammatory/immune responses. The current knowledge of the distribution of cell adhesion molecules is described and the potential for modulation of cell adhesion molecule function is discussed.

Differential effects of Na+, K(+)-ATPase inhibition by ouabain on acid secretory responses to histamine and bethanechol in the mouse isolated stomach

1. The effect of Na+,K(+)-ATPase inhibition by ouabain on gastric acid secretion was studied in the mouse isolated whole stomach preparation. 2. Ouabain caused a transient enhancement of histamine-induced gastric acid secretion followed by an inhibitory phase. On the other hand, ouabain caused a rapid reduction of bethanechol-stimulated acid secretion without an enhancement phase. 3. In dibutyryl cyclic AMP-induced acid secretion, ouabain led to a transient increase in acid secretion followed by a fall, as was seen with the histamine stimulation. Ouabain caused a rapid reduction of A23187-induced acid secretion. 4. Ouabain by itself increased basal acid secretion, and thereafter slowly suppressed the acid secretion. 5. Atropine inhibited both the ouabain-induced enhancement of the stimulated gastric acid secretion and the ouabain-induced stimulation of basal acid secretion. 6. The present study showed that Na+,K(+)-ATPase inhibition by ouabain caused a phasic enhancement of the stimulated gastric acid secretion through release of endogenous acetylcholine when the secretagogues act via an intracellular cyclic AMP pathway. It also inhibited the stimulated acid secretion irrespective of secretagogues, probably through its inhibitory effect on Na+,K(+)-ATPase in the gastric parietal cell.

In vitro antibacterial activity of FK037, a new parenteral broad-spectrum cephalosporin, against recent clinical isolates in the fields of obstetrics and gynecology

The antibacterial activity of a new parenteral cephalosporin, FK037 was assessed against recent aerobic and anaerobic strains isolated from patients in the fields of obstetrics and gynecology during the period between January 1992 and June 1993. The MICs of FK037 for 90% of the clinical isolates tested were 0.10 microgram/ml for Escherichia coli and Klebsiella pneumoniae, 0.20 microgram/ml for Streptococcus agalactiae, 0.39 microgram/ml for Gardnerella vaginalis, 0.78 microgram/ml for Staphylococcus epidermidis, Peptostreptococcus anaerobius and Mobiluncus spp., 1.56 micrograms/ml for Peptostreptococcus magnus, 3.13 micrograms/ml for methicillin-sensitive Staphylococcus aureus, 25 micrograms/ml for methicillin-resistant S. aureus (MRSA), Bacteroides fragilis and Prevotella disiens, 100 micrograms/ml for Bacteroides thetaiotaomicron and Prevotella bivia; and > 100 micrograms/ml for Enterococcus faecalis. FK037 was superior in potency to ceftazidime against all strains except E. faecalis, P. anaerobius and P. bivia. It was 4- to 16-fold more active than cefotaxime against aerobic gram-positive bacteria and P. disiens, and its activity was similar to that of cefotaxime against the other strains. FK037 had 4- to 16-fold stronger activity than flomoxef against MRSA, S. agalactiae and E. coli and a similar activity to flomoxef against the other strains except G. vaginalis and B. fragilis that were 4-fold more sensitive to flomoxef than to FK037.

[Role of clinical laboratory physicians in clinical hematology]

The specialty for laboratory hematology has been difficult to define in Japan, since both the clinical laboratory physician and clinical hematologist usually engage in this field. I propose herein that the specialty for laboratory hematology belongs to laboratory medicine. This makes it possible for the clinical laboratory physician to provide active medical assistance for laboratory diagnosis of hematological disorders so that the clinical hematologist can effectively perform practical management of the patient. For this purpose, I describe the program of postgraduate education for doctors in laboratory hematology. General instructional objectives (GIOs) and specific behavioral objectives (SBOs) are proposed to set the education program for clinical laboratory physicians and to establish the specialty of laboratory hematology in Japan. For the establishment of this system, the committee for the Japanese educational program for the medical board should authorize this newly developed conception for the clinical laboratory physicians who work in the hematology laboratory.

Computed tomography of an intracranial lipoma confined in the suprasellar cistern

A case of large intracranial lipoma involving the suprasellar cistern is presented in a 50-yr-old man with a history of occipital headaches. Evaluations by routine computed tomography (CT) combined with metrizamide CT cisternography were extremely useful in the diagnosis of this rare condition. Intracranial lipomas are reviewed in the literature and the role of CT evaluations is discussed.

Efficient expression of E. coli dihydrofolate reductase gene by an in vitro translation system using phosphorothioate mRNA

Dihydrofolate reductase (DHFR) of Escherichia coli (E. coli) was synthesized in a cell-free translation system of E. coli directed by phosphorothioate-containing mRNA (thio-mRNA) which was polymerized by an in vitro transcription of the DHFR gene in the presence of SP diastereomers of ribonucleoside 5'-O-(1-thiotriphosphates). The molecular weights of the products thus obtained were identical to those with the unsubstituted mRNA. Furthermore, the thio-mRNA for DHFR showed higher translational activities than the corresponding unsubstituted mRNA. It is suggested that this effectiveness resulted from the higher stability of thio-mRNA in the cell-free translation system. Amongst the various types of thio-mRNAs, the single substitution of adenosine residues was most effective in translational activity. This higher translational activity of thio-mRNA compared with the unsubstituted mRNA was also demonstrated in a continuous flow cell-free system originally developed by Spirin et al. (1988). Therefore, introduction of sulfur atoms into phosphodiester bonds of mRNA appears to be a useful strategy for the stabilization of mRNA in large-scale protein production in vitro.

Scaphoid fracture as a "puncher's fracture"

We investigated 18 scaphoid fractures induced by punching. The wrist position while punching was neutral to slight palmar flexion. We postulated that the mechanism of the fracture was caused by the concentration of the external force to the second metacarpus. The forces are then dispersed to the trapezium and trapezoid, which produces shear stress at the waist of the scaphoid. In spite of the differences in mechanism, the location of the fracture was similar to fractured scaphoids caused by wrist extension injuries. Regardless of the wrist positions, the carpal scaphoid is most vulnerable to fracture due to its characteristic morphology.

Molecular cloning of brevican, a novel brain proteoglycan of the aggrecan/versican family

To clone novel brain proteoglycans, we employed a strategy based on polyclonal antisera that recognize multiple proteoglycan core proteins. By using an antiserum raised against a fraction enriched for proteoglycans, we isolated three groups of cDNAs from a bovine brain lambda gt11 library. One of the cDNA groups has been fully sequenced and shown to encode a novel proteoglycan core protein of the aggrecan/versican family. This proteoglycan, named brevican, carries chondroitin sulfate chains, and, like other members of the family, contains a hyaluronic acid-binding domain in its N-terminal region, an epidermal growth factor-like repeat, a lectin-like and a complement regulatory protein-like domains in its C-terminal region. In contrast, the central region of brevican is much shorter than that of aggrecan, versican, or neurocan, and shows little homology with these proteoglycans. Brevican core protein exists as a 145 kDa full-length form and a 80 kDa N terminally truncated form. A significant amount of brevican devoid of any glycosaminoglycan chains is present in the brain, indicating that brevican is a "part-time" proteoglycan. Northern blot analysis reveals that a single 3.3-kilobase brevican transcript is present predominantly in the brain, and that it is expressed in primary cerebellar astrocytes but not in neurons.