On fatigue lifetimes and fatigue crack growth behavior of bone cement

Bone cement is used to develop a mechanical bond between an artificial joint and the adjacent bone tissue, and any degradation of this bond is of serious concern since it can lead to loosening and eventually malfunction of the artificial joint. In the present study, the fatigue lives and fatigue crack propagation behavior of two bone cements, CMW Type 3 and Zimmer, were investigated, and it was found that the size and distribution of pores played a major role in influencing both the fatigue crack initiation and propagation processes. The fatigue lifetimes of CMW exceeded those of Zimmer because of a lesser density of large pores. When the fatigue lifetimes were plotted as a function of Klimax, the maximum initial stress intensity factor based upon the initiating pore size, the difference in fatigue lifetimes between CMW and Zimmer bone cements was greatly reduced. The fatigue crack growth behavior of both bone cements were similar. This is a further indication that the noted differences in fatigue lifetimes were related to the size of the pore at the crack initiating site.

Cloning and functional expression of Rpn1, a regulatory-particle non-ATPase subunit 1, of proteasome from Trypanosoma cruzi

Non-lysosomal protein degradation in eukaryotic cells involves a proteolytic complex referred to as 26S proteasome that consists of a 20S core particle and one or two 19S regulatory particles. We have cloned the gene RPN1 encoding Rpnl (regulatory-particle non-ATPase subunit 1), one of the largest subunits of proteasome, from Trypanosoma cruzi. It contains 2712 bp and encodes 904 amino acid residues with a calculated molecular mass of 98.2 kDa and an isoelectric point of 5.2. The predicted amino acid sequence of the trypanosomatid Rpn1 shares 39.0 and 32.0% overall identities with human Rpn1 and Saccharomyces cerevisiae Nas1 (non-ATPase subunit 1), an Rpn1 homolog, respectively, while the sequence identities among T. cruzi, Plasmodium falciparum, and Entamoeba histolytica Rpnl are approximately 30%. T. cruzi Rpn1 contains nine repeats of about 36 amino acid residues conserved in Rpn1s from various organisms. T. cruzi RPN1 is located on the 2300- and 1900-kb chromosomal DNA, displays a putative allelic variation as RPN1-1 and RPN1-2 with 98.8% identity between these two putative gene products, and is transcribed from both alleles at a comparable level throughout the three developmental stages of the parasite, epimastigotes, trypomastigotes, and amastigotes. The expression of the trypanosomatid Rpnl in the temperature-sensitive nas1 yeast mutant rescued the growth defect at the restrictive temperature, indicating that Rpn1 functions as a Nas1 and probably assembles into the 19S regulatory particle of the yeast 26S proteasome.

Regional specificity of localized cortical lesions in West syndrome

West syndrome, although classified as a generalized epilepsy, is associated with localized cerebral lesions in some cases. However, similar localized cortical abnormalities usually can result in partial epilepsy, instead of West syndrome. We performed this study to determine the additional factors that result in West syndrome instead of partial epilepsy in patients with localized cerebral lesions. We reviewed the pathologic features, topographic localization, and side of unilaterally defined cerebral lesions in relation to the seizure types in 39 epileptic patients, including five patients who presented with West syndrome. The lesions of all five patients with West syndrome involved the temporal or occipital lobes (or both). Among the nine with an occipital lesion, four had West syndrome. In the 19 with a temporal lesion, three had West syndrome. However, in the 16 patients with a frontal lesion, none exhibited epileptic spasms. In four of the five with West syndrome the lesions were on the right side; 23 had lesions on the right, 16 had them on the left. Temporo-occipital lesions and lesions on the right were related to the genesis of West syndrome, which would be in close correlation with normal brain maturation.

Characterization of interaction of C- and N-terminal domains in LIM15/DMC1 and RAD51 from a basidiomycetes, Coprinus cinereus

Both LIM15/DMC1 and RAD51 are thought to be essential for meiosis in which homologous chromosomes pair and recombine. The primary purpose of the present study was to investigate the homotypic and heterotypic interactions among their terminal domains. We prepared cDNAs and recombinant proteins of the full-length, N-terminal, and the C-terminal domains of LIM15/DMC1 (CoLIM15) and RAD51 (CoRAD51) from the basidiomycete Coprinus cinereus. In both two-hybrid assay in vivo and pull-down assay in vitro, either CoLim15 or CoRad51 interacted homotypically between the C-terminal domains, respectively, but no heterotypic interaction was observed between CoLim15 and CoRad51. The N-terminal domain of CoLim15 bound to ssDNA and dsDNA, while the C-terminal domain of CoRad51 appeared to interact weakly with ssDNA. Based on these results, the interaction among the strand-exchange proteins and meiosis was discussed.

Inhibition of Fas-mediated apoptosis by Trypanosoma cruzi infection

Trypanosoma cruzi-infected and normal control mammalian cells were subjected to analysis of Fas-mediated apoptosis stimulated by an agonistic anti-Fas monoclonal antibody. The infected cells showed markedly hampered apoptotic changes in nuclear morphology, phosphatidylethanolamine translocation from the inside to the outside of the plasma membrane, and DNA fragmentation into multiples of 180 bp, relative to normal control cells. Upstream of these morphological and biochemical consequences, the caspase-3 activity was elevated by the Fas stimulation in a significantly greater proportion of intact control cells, but at a highly reduced rate of infected cells. The rapid elevation of caspase-8 activity in control, apoptotic cells was completely inhibited in infected cells. In an examination of the specificity of other stimulants, X-ray radiation or chemicals such as hydrogen peroxide, colchicine or etoposide did not cause significant differences in apoptotic rates between control and infected cells; tumor necrosis factor-alpha, however, induced a high rate of apoptosis in control cells, with an extremely lowered rate in infected cells. This study demonstrates, for the first time, that T. cruzi infection inhibits one of the earliest steps of death receptor-mediated apoptosis, an effect that most probably involves the inhibition of caspase-8. Differential apoptotic responses in cells infected with T. cruzi and other intracellular parasites are discussed.

[Epileptogenesis of acute encephalitis and acute encephalopathy: epilepsy with its onset in the acute phase and without a latent period]

Epileptogenesis was evaluated in 60 patients with acute encephalitis and in 10 patients with acute encephalopathy. Forty-seven patients have been seizure-free during for more than three years' follow-up (Group III). On the other hand, 23 patients developed epilepsy. Among them, 18 patients developed epilepsy after a latent period of 1 month to 2 3/12 years (Group I). In Group I, a younger age of the onset, a long period of disturbed consciousness and a high activity of CSF neuron-specific enolase (NSE) was associated with refractory epilepsy. The other five patients had continuous seizures from the acute phase of encephalitis without a latent period (Group II). They had more than 2 types of partial motor seizures which occurred frequently during the acute phase of encephalitis. The NSE activity in the CSF of patients in Group II was less than 50 ng/ml, being similar to those in Group III. The epilepsy in Group II, however, was the most refractory. The reason for the development of this continuous refractory epilepsy remained obscure.

Vaccination of domestic pig with recombinant paramyosin. against Schistosoma japonicum in China

Paramyosin (PM), a myosin-like protein is a major antigen on Schistosoma japonicum (Sj). We reported that passive transfer of a monoclonal IgE SjE18varepsilon.1 which recognizes PM of Sj (SJPM), partially protected mice from challenge infection. In the present study, we developed an experimental model system of schistosomiasis japonica with domestic pigs in China and used it for the evaluation of vaccination with recombinant SJPM (rSJPM). Sixteen-week-old pigs were successfully infected by dermal penetration of 120 cercariae of a domestic strain of Sj (50-60% worm recovery 11 weeks after challenge). The pigs vaccinated with 400 UV attenuated cercariae showed a reduction of worm recovery (53%, p<0.001). The experimental groups were immunized intradermally with rSJPM and alum or TiterMax and were partially protected against the challenge infection (32-35% reduction).

Drug extrusion in Corynebacterium glutamicum

We selected a mutant of Corynebacterium glutamicum, EBR, which can grow in a medium containing cytotoxic ethidium bromide (EtBr) at a high concentration of 100 microM. The resistance to EtBr in the mutant was reversed by 2 microM reserpine, a potent inhibitor of mammalian p-glycoprotein and bacterial multidrug resistance (MDR) transporter, whereas reserpine alone had a minimal effect on cell growth. The mutant showed a much higher efflux rate of EtBr than wild-type cells, and the efflux was completely inhibited by 2 microM reserpine. In addition to reserpine, structurally unrelated chemicals such as quinidine, trifluorperazine, tetraphenylarsonium chloride, chlorpromazine and quinine inhibit the EtBr efflux, revealing that the putative efflux system(s) can recognize a variety of chemicals. The efflux activity was correlated with the membrane potential but not the intracellular ATP contents. We, therefore, concluded that the EtBr resistance may be involved by proton-motive-force driven multidrug efflux system(s).

Isolation of a LIM15/DMC1 homolog from the basidiomycete Coprinus cinereus and its expression in relation to meiotic chromosome pairing

The Escherichia coli gene recA is essential for homologous recombination and DNA repair, and homologs have been identified in eukaryotes. A basidiomycete, Coprinus cinereus, which has many advantages for the study of meiosis, was recently reported to have a homolog of one of these, RAD51. In the yeast Saccharomyces, mutations in the RAD51 gene cause defects in both somatic and meiotic cells. Based on this finding, we screened for a meiosis-specific homolog of recA, equivalent to Lilium LIM15 or Saccharomyces DMC1, in C. cinereus, and isolated a clone containing a 1.2-kb DNA fragment from a cDNA library constructed with Coprinus poly(A)+ RNA isolated from cells undergoing meiosis. The predicted amino acid sequence was 52% identical to the putative gene product of the lily cDNA clone LIM15 and 61% identical to Saccharomyces DMC1, and showed limited sequence similarity to the products of RAD52, 55, and 57. The synchrony of meiosis in Coprinus provides an ideal system for the investigation of differential gene expression in relation to meiosis and fruiting body development. Northern analysis indicated that Coprinus LIM15/DMC1 was expressed at meiotic prophase within 8 h after the onset of karyogamy, suggesting that the gene functions mostly at the stage at which the homologous chromosomes pair, but may not be essential at the point at which they recombine. The gene is not expressed in somatic cells.

[Morphometric development and the variability of neurons of the human auditory system: ventral cochlear nucleus and superior medial olivary nucleus]

The development of the human ventral cochlear and medial superior olivary nuclei was studied. We made serial sections of the brain in 10 fetuses at 16-40 weeks of gestation (WG), an infant at 2 months of age and an adult of 63 years using an electronic planimeter with a computer. Although the shape of neurons of the two nuclei was different, our morphometric analysis showed that the development of both of them accelerates between 18 and 21 WG in terms of the columnar length and volume, neuronal size and circularity ratio and the amount of Nissl bodies increases gradually.

[Topography and number of cortical tubers in tuberous sclerosis: comparison between patients with and without West syndrome]

To reveal the role of cortical tubers in the pathophysiology of West syndrome associated with tuberous sclerosis, we studied their numbers and topography, focusing on the differences between patients with infantile spasms and without infantile spasms. We reviewed the clinical date on the seizure types, seizure evolution and developmental status of 13 patients: 8 patients with infantile spasms (the West syndrome group) and 5 patients without infantile spasms (the non-West syndrome group). The number, size and location of the cortical tubers were evaluated on 5 mm-thick T2-weighted MR images. The average number of cortical tubers of the West syndrome group was 11.4 per patient, being larger than that of the non-West syndrome group (7.8). The West syndrome group included two patients with only one tuber. The average number of the cortical tubers in the occipital lobes of the West syndrome group was 2.4, which was larger than that of the non-West syndrome group (0.8). From these results, a large number of cortical tubers, which suggest involvement of larger cerebral cortical regions, increase the possibility of the West syndrome in patients with tuberous sclerosis. On the other hand, some patients with only one or few cortical tubers developed West syndrome, which may suggest the presence of a region critical on the development of West syndrome. Our results also suggest that lesions in the occipital lobes might be more significant than those in other lobes. However, the results of this study are diverse, to some extent, which may have resulted from variable epileptogenicity of the cortical tubers. It is necessary to conduct further study, including a greater number of patients, to reveal topographic pathophysiology in West syndrome.

Intrathecal co-administration of NMDA antagonist and NK-1 antagonist reduces MAC of isoflurane in rats

BACKGROUND

Intravenous administration of N-methyl-D-aspartate (NMDA) receptor antagonists and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor antagonists reportedly reduce the minimum alveolar anaesthetic concentration (MAC) for inhalation anaesthetics. If pain perception can be prevented by the intrathecal administration of antinociceptive receptor antagonists, these agents may reduce the requirements for inhalation anaesthetics. We studied the effect of intrathecal administration of an AMPA/kainate receptor antagonist, a metabotropic glutamate (mGlu) receptor antagonist and co-administration of NMDA and a neurokinin-1(NK-1) receptor antagonist drugs at low doses on the MAC.

METHODS

After Wistar rats (n=36) were fitted with indwelling intrathecal catheters, the MAC of isoflurane was determined following intrathecal administration of a non-NMDA receptor antagonist (CNQX) at 10 microg, a mGlu receptor antagonist (AP3) at 10 microg, or a combination of NMDA receptor antagonist (APV) at 0.01 microg to 1 microg with NK-1 receptor antagonist (CP96345, CP) at 0.1 microg to 10 microg. Subsequently, a reversal dose of intrathecal NMDA with substance P (SP) was administered, and the MAC of isoflurane was redetermined. Conscious rats (n=15) were also examined for the presence of locomotor dysfunction following the intrathecal co-administration of APV and CP.

RESULTS

Neither CNQX nor AP3 reduced the MAC of isoflurane. APV at 0.01 microg plus CP at 1 microg, as well as APV at 0.1 microg plus CP at 10 microg, reduced the MAC of isoflurane, with respective reductions of 7.6% and 14%; (P<0.05). Co-administration of NMDA plus SP reversed the decrease in the MAC of isoflurane. Locomotive activity was not changed.

CONCLUSIONS

The NMDA receptor and the NK-1 receptor are important determinants of the MAC of isoflurane, exerting this influence by inhibition of pain transmission in the spinal cord, while mGlu and AMPA receptors have no effect on the MAC of isoflurane.

[Lissencephaly type I: electroencephalographic findings and neuroradiological classification]

Lissencephaly type I is a diffuse type of migration disorder that contains agyria and/or pachygyria on the brain surface. We experienced 5 cases of this disease and evaluated their electroencephalographic findings and seizure types based on the neuroradiological classification of lissencephaly. Ages at seizure onset ranged from 2 months to 4 months (mean 3.2 months). The patients with complete agyria had generalized tonic seizures, and those with pachygyria partial seizures or tonic spasms. The characteristic findings of complete agyria in electroencephalogram were high-voltage alfa activity. The amount of high-voltage slow waves increased with the ratio of pachygyria on the brain surface. The appearance of multifocal spikes and sharp waves suggested irregular arrangement of pachygyria on the brain surface.

Conversion of a bacterial warm sensor to a cold sensor by methylation of a single residue in the presence of an attractant

The aspartate chemoreceptor (Tar) of Escherichia coli also serves as a thermosensor, and it is very amenable to genetic and biochemical analysis of the thermosensing mechanism. Its thermosensing properties are controlled by reversible methylation of the cytoplasmic signalling/adaptation domain of the protein. The unmethylated and the fully methylated (aspartate-bound) receptors sense, as attractant stimuli, increases (warm sensor) and decreases (cold sensor) in temperature respectively. To learn more about the mechanism of thermosensing, we replaced the four methyl-accepting glutamyl residues with non-methylatable aspartyl residues in all possible combinations. In a strain defective in both methyltransferase (CheR) and methylesterase (CheB) activities, all of the mutant Tar proteins functioned as warm sensors. To create a situation in which all of the remaining glutamyl residues were methylated, we expressed the mutant proteins in a CheB-defective, CheR-overproducing strain. The fully glutamyl-methylated proteins were designed to mimic the full range of methylation states possible for wild-type Tar. Almost all of the methylated mutant receptors, including those with single glutamyl residues, were cold sensors in the presence of aspartate. Thus, binding of aspartate to Tar and methylation of its single glutamyl residue can invert its temperature-dependent signalling properties.

The effect of intrathecal magnesium sulphate on nociception in rat acute pain models

We examined the antinociceptive effect of intrathecally administered magnesium sulphate (MgSO4) in rats, using acute pain models including mechanical pressure, heat and subcutaneous formalin injection. According to the locomotion test 10 microliters of 6.2% MgSO4 did not produce motor paralysis. At the same dose, responses to pressure and heat were intact, compared with controls given saline. MgSO4 produced depression of pain responses only after the first 10 min in the formalin test. Our studies indicated that MgSO4 did not show remarkable antinociceptive effects in acute pain models.

Induction of CD8+ T cell-mediated protective immunity against Trypanosoma cruzi

Trypanosoma cruzi was transformed with the Plasmodium yoelii gene encoding the circum-sporozoite (CS) protein, which contains the well-characterized CD8+ T cell epitope, SYVPSAEQI. In vivo and in vitro assays indicated that cells infected with the transformed T. cruzi could process and present this malaria parasite-derived class I MHC-restricted epitope. Immunization of mice with recombinant influenza and vaccinia viruses expressing the SYVPSAEQI epitope induced a large number of specific CD8+ T cells that strongly suppressed parasitemia and conferred complete protection against the acute T. cruzi lethal infection. CD8+ T cells mediated this immunity as indicated by the unrelenting parasitemia and high mortality observed in immunized mice treated with anti-CD8 antibody. This study demonstrated, for the first time, that vaccination of mice with vectors designed to induce CD8+ T cells is effective against T. cruzi infection.

Novel organization and sequences of five genes encoding all six enzymes for de novo pyrimidine biosynthesis in Trypanosoma cruzi

A 25 kb segment of genomic DNA from Trypanosoma cruzi, the causative agent of Chagas' disease, was sequenced. It contains five genes, pyr1, pyr2, pyr3, pyr4, and pyr6-5, encoding all six enzymes involved in de novo pyrimidine biosynthesis, glutamine-dependent carbamoyl-phosphate synthetase, aspartate carbamoyltransferase, dihydroorotase, dihydroorotate dehydrogenase, and orotidine-5'-phosphate decarboxylase linked with orotate phosphoribosyltransferase, respectively. The pyr genes constitute a polycistronic transcription unit on an 800 kb chromosomal DNA in the order of pyr1, pyr3, pyr6-5, pyr2, and pyr4 from the 5' terminus, with intervening sequences of 2.2, 0.4, 8.1, and 0.8 kb. The amino acid sequences deduced from the trypanosomatid pyr genes, except for pyr6, showed closer similarities to mammalian and yeast sequences, and less similarity to archaeal and bacterial sequences. The last two enzymes encoded by a single gene, pyr6-5, are covalently linked in the order opposite to mammalian pyr5-6, and possess a putative glycosomal targeting signal tripeptide, serine-lysine-leucine, at the C terminus. The calculated isoelectric points of 9.3 and 9.9 are also diagnostic of the glycosomal localization of these enzymes. We conclude that the T. cruzi pyr gene organization represents an early progenitor in de novo pyrimidine biosynthesis in eukaryotic lineage, and that the independent pyr genes may have evolved before the gene fusion events that resulted in the three mammalian-type genes, pyr1-3-2, pyr4, and pyr5-6, for UMP synthesis. Peculiarities in the trypanosomatid pyr6-5 gene product are discussed.

[Childhood multiple sclerosis and allied demyelinative diseases]

We report five cases of multiple sclerosis (MS) and three cases of allied demyelinative diseases starting during childhood. Three of the MS patients presented with atypical initial symptoms, such as acute encephalitis or myelitis, making an early clinical diagnosis difficult. Ophthalmologic symptoms were noted in four of MS children, and in two with allied demyelinative diseases. Therefore, if a child shows ophthalmologic symptoms (i.e. optic neuritis, ophthalmoplegia), brain magnetic resonance imaging (MRI) should be conducted for the differential diagnosis of MS and other demyelinative diseases. Cerebrospinal fluid analysis is not useful for the initial diagnosis of MS, because pleocytosis and increase of oligoclonal IgG band in cerebrospinal fluid are seen in both MS and other demyelinative disorders. However, neuron specific enolase (NSE) is slightly higher in the latter than in the former. T2-weighted MRI of multiple sclerosis showed multiple high intensity areas in the white matter of the cerebrum and cerebellum, capsula interna, and crus cerebri etc. Most of these lesions were clinically silent, being characteristic of MS. In two MS cases, however, initial MRI revealed no abnormal findings. Thus, the diagnosis of MS can not be made by initial MRI only.

High predictive value of red cell volume measurement using carboxy-haemoglobin in a rabbit model of haemorrhage

We have studied the accuracy of blood volume measurements using carbon monoxide (CO)-labelled haemoglobin (COHb) injection and dilution (CO method) by comparing changes in red cell volume (RCV) measured using the CO method and 51Cr-labelled erythrocyte dilution (51Cr method) in a haemorrhage and infusion model in rabbits. RCV was measured repeatedly using the CO method at four different blood volume stages (stages I-IV). At stages I and IV, RCV was measured simultaneously using the 51Cr method. In comparing the sum of the circulating RCV and extracted RCV (SUM RCV) using the CO method, the values were almost equal and there were no significant differences between the values at the four stages. In comparing circulating RCV measured using the CO method and the 51Cr method, mean difference between the two methods was 0.80 (SD 0.76) ml kg-1 or 4.7 (4.6)%, and a positive correlation was observed (r = 0.91). We conclude that the CO method can be used to measure blood volume during perioperative periods in infants because it avoids use of a radioactive tracer, is simple and repeated measurements are possible.

Carbamoyl-phosphate synthetase II in kinetoplastids

Genes for carbamoyl-phosphate synthetase II (CPS II), the first enzyme of de novo pyrimidine biosynthesis, were cloned from kinetoplastids, Trypanosoma cruzi and Leishmania mexicana. T. cruzi CPS II gene encodes a protein of 1524 amino acids that encompasses the glutaminase and CPS domains, but incorporates neither aspartate carbamoyltransferase nor dihydroorotase. The residue corresponding to lysine 993 of Escherichia coli CPS, a residue that characterizes the CPS inhibited by UMP and that is replaced by tryptophan in those inhibited by UTP, is in kinetoplastids a hydrophilic glutamine, in line with the preferential inhibition by UDP of kinetoplastid CPS II.

Electron microscopic examination of oligocilia in naevus of Ota

The structure of the cilia present in dermal melanocytes of 14 patients with naevus of Ota was examined by electron microscopy. Cilia and basal bodies were found in 10 and 9 lesions, and in 39 and 18 dermal melanocytes, respectively. In each case, 1-12 cells with a single cilium or multiple cilia were observed. In a total of 3 dermal melanocytes from 2 cases, two cilia per cell were observed. The cilia contained 7, 6, 5 and 4 pairs of doublet microtubules in the periphery and no central microtubule. Another pattern with several pairs of doublet microtubules in the periphery and one or two centrally located doublet microtubules were also observed. The latter were not bona fide central microtubules but one and two doublets, which seemed to be displaced to the centre from the periphery of the cilium.