Impact of COVID-19 and Closed Transmission of SARS-CoV-2 during the First Wave in Toyama Prefecture, Japan, March 30 to May 18, 2020

We studied 226 patients in Toyama Prefecture who were notified of COVID-19 during the first wave between March 30 and May 18, 2020. Of the 226 patients, 22 (9.7%) died, most (95%) of whom were aged ≥65 years. A large cluster comprising 59 patients (41 residents and 18 staff members) was identified in a nursing home on April 17. No deaths occurred among staff members; however, 12 of the 41 residents (29%) died. Although the threshold cycle (Ct) values were significantly lower in the 20-64 and ≥65 years age groups than in the <20 years age group, no correlation was found between the Ct values and severity, fatal outcome, or secondary infection. The haplotype network of 145 SARS-CoV-2 isolates (64%) from 226 patients was analyzed. The viral genomes of the case groups differed by less than five nucleotide bases. These data suggest that the SARS-CoV-2 strains, which were initially introduced into Toyama Prefecture in late March and early April 2020, and their closely related strains, identified as lineage B.1.1, circulated during the first wave. The reduced inter-prefectural mobility of local residents may support the lack of strain diversity in SARS-CoV-2 during the first wave of the state of emergency.

Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

Interaction between PI3K and the VDAC2 channel tethers Ras-PI3K-positive endosomes to mitochondria and promotes endosome maturation

Intracellular organelles of mammalian cells communicate with one another during various cellular processes. The functions and molecular mechanisms of such interorganelle association remain largely unclear, however. We here identify voltage-dependent anion channel 2 (VDAC2), a mitochondrial outer membrane protein, as a binding partner of phosphoinositide 3-kinase (PI3K), a regulator of clathrin-independent endocytosis downstream of the small GTPase Ras. VDAC2 tethers endosomes positive for the Ras-PI3K complex to mitochondria in response to cell stimulation with epidermal growth factor and promotes clathrin-independent endocytosis, as well as endosome maturation at membrane association sites. With an optogenetics system to induce mitochondrion-endosome association, we find that, in addition to its structural role in such association, VDAC2 is functionally implicated in the promotion of endosome maturation. The mitochondrion-endosome association thus plays a role in the regulation of clathrin-independent endocytosis and endosome maturation.

Neutralization of Omicron subvariants BA.1 and BA.5 by a booster dose of COVID-19 mRNA vaccine in a Japanese nursing home cohort

The sustained epidemic of Omicron subvariants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a worldwide concern, and older adults are at high risk. We conducted a prospective cohort study to assess the immunogenicity of COVID-19 mRNA vaccines (BNT162b2 or mRNA-1273) in nursing home residents and staff between May 2021 and December 2022. A total of 335 SARS-CoV-2 naïve individuals, including 141 residents (median age: 88 years) and 194 staff (median age: 44 years) participated. Receptor-binding domain (RBD) and nucleocapsid (N) protein IgG and neutralizing titer (NT) against the Wuhan strain, Alpha and Delta variants, and Omicron BA.1 and BA.5 subvariants were measured in serum samples drawn from participants after the second and third doses of mRNA vaccine using SARS-CoV-2 pseudotyped virus. Breakthrough infection (BTI) was confirmed by a notification of COVID-19 or a positive anti-N IgG result in serum after mRNA vaccination. Fifty-one participants experienced SARS-CoV-2 BTI during the study period. The RBD IgG and NTs against Omicron BA.1 and BA.5 were markedly increased in SARS CoV-2 naïve participants 2 months after the third dose of mRNA vaccine, compared to those 5 months after the second dose, and declined 5 months after the third dose. The decline in RBD IgG and NT against Omicron BA.1 and BA.5 in SARS-CoV-2 naïve participants after the second and the third dose was particularly marked in those aged ≥ 80 years. BTIs during the BA.5 epidemic period, which occurred between 2 and 5 months after the third dose, induced a robust NT against BA.5 even five months after the booster dose vaccination. Further studies are required to assess the sustainability of NTs elicited by Omicron-containing bivalent mRNA booster vaccine in older adults.

Viral isolation analysis of SARS-CoV-2 from clinical specimens of COVID-19 patients

Genetic testing using reverse transcriptase real-time polymerase chain reaction (rRT-PCR) is the mainstay of diagnosis of COVID-19. However, it has not been fully investigated whether infectious viruses are contained in SARS-CoV-2 genome-positive specimens examined using the rRT-PCR test. In this study, we examined the correlation between the threshold Cycle (Ct) value obtained from the rRT-PCR test and virus isolation in cultured cells, using 533 consecutive clinical specimens of COVID-19 patients. The virus was isolated from specimens with a Ct value of less than 30 cycles, and the lower the Ct value, the more efficient the isolation rate. A cytopathic effect due to herpes simplex virus type 1 contamination was observed in one sample with a Ct value of 35 cycles. In a comparison of VeroE6/TMPRSS2 cells and VeroE6 cells used for virus isolation, VeroE6/TMPRSS2 cells isolated the virus 1.7 times more efficiently than VeroE6 cells. There was no significant difference between the two cells in the mean Ct value of the detectable sample.

In conclusion, Lower Ct values in the PCR test were associated with higher virus isolation rates, and VeroE6/TMPRSS2 cells were able to isolate viruses more efficiently than VeroE6 cells.

Localization of BCR-ABL to Stress Granules Contributes to Its Oncogenic Function

The oncogenic tyrosine kinase BCR-ABL activates a variety of signaling pathways and plays a causative role in the pathogenesis of chronic myelogenous leukemia (CML); however, the subcellular distribution of this chimeric protein remains controversial. Here, we report that BCR-ABL is localized to stress granules and that its granular localization contributes to BCR-ABL-dependent leukemogenesis. BCR-ABL-positive granules were not colocalized with any markers for membrane-bound organelles but were colocalized with HSP90a, a component of RNA granules. The number of such granules increased with thapsigargin treatment, confirming that the granules were stress granules. Given that treatment with the ABL kinase inhibitor imatinib and elimination of the N-terminal region of BCR-ABL abolished granule formation, kinase activity and the coiled-coil domain are required for granule formation. Whereas wild-type BCR-ABL rescued the growth defect in IL-3-depleted Ba/F3 cells, mutant BCR-ABL lacking the N-terminal region failed to do so. Moreover, forced tetramerization of the N-terminus-deleted mutant could not restore the growth defect, indicating that granule formation, but not tetramerization, through its N-terminus is critical for BCR-ABL-dependent oncogenicity. Our findings together provide new insights into the pathogenesis of CML by BCR-ABL and open a window for developing novel therapeutic strategies for this disease.Key words: BCR-ABL, subcellular localization, stress granule.

Folding Latency of Fluorescent Proteins Affects the Mitochondrial Localization of Fusion Proteins

The discovery of fluorescent proteins (FPs) has revolutionized cell biology. The fusion of targeting sequences to FPs enables the investigation of cellular organelles and their dynamics; however, occasionally, such fluorescent fusion proteins (FFPs) exhibit behavior different from that of the native proteins. Here, we constructed a color pallet comprising different organelle markers and found that FFPs targeted to the mitochondria were mislocalized when fused to certain types of FPs. Such FPs included several variants of Aequorea victoria green FP (avGFP) and a monomeric variant of the red FP. Because the FFPs that are mislocalized include FPs with faster maturing or folding mutations, the increase in the maturation rate is likely to prevent their expected localization. Indeed, when we reintroduced amino acid substitutions so that the FP sequences were equivalent to that of wild-type avGFP, FFP localization to the mitochondria was significantly enhanced. Moreover, similar amino acid substitutions improved the localization of mitochondria-targeted pHluorin, which is a pH-sensitive variant of GFP, and its capability to monitor pH changes in the mitochondrial matrix. Our findings demonstrate the importance of selecting FPs that maximize FFP function.Key words: fluorescent protein, organelle, fusion protein, mitochondria.

Cytoprotective Effects of Mesenchymal Stem Cells During Liver Transplantation from Donors After Cardiac Death in Rats

BACKGROUND

Liver transplantation from donors after cardiac death (DCD) might increase the pool of available organs. Recently, some investigators reported the potential use of mesenchymal stem cells (MSCs) to improve the outcome of liver transplantation from DCD. The aim of this study was to evaluate the cytoprotective effects and safety of MSC transplantation on liver grafts from DCD.

METHODS

Rats were divided into 4 groups (n = 5) as follows: 1. the heart-beating group, in which liver grafts were retrieved from heart-beating donors; 2. the DCD group, in which liver grafts were retrieved from DCD that had experienced apnea-induced agonal conditions; 3. the MSC-1 group, and 4. the MSC-2 group, in which liver grafts were retrieved as with the DCD group, but were infused MSCs (2.0 × 10⁵ or 1.0 × 10⁶, respectively). The retrieved livers were perfused with oxygenated Krebs-Henseleit bicarbonate buffer (37°C) through the portal vein for 2 hours after 6 hours of cold preservation. Perfusate, bile, and liver tissues were then investigated.

RESULTS

Bile production in the MSC-2 group was significantly improved compared with that in the DCD group. Based on histologic findings, narrowing of the sinusoidal space in the both MSC groups was improved compared with that in the DCD group.

CONCLUSIONS

MSCs could protect the function of liver grafts from warm ischemia-reperfusion injury and improve the viability of DCD liver grafts. In addition, we found that the infusion of 1.0 × 10⁶ MSCs does not obstruct the hepatic sinusoids of grafts from DCD.

Intranasal Administration of Rotenone to Mice Induces Dopaminergic Neurite Degeneration of Dopaminergic Neurons in the Substantia Nigra

Exposure to environmental neurotoxins is suspected to be a risk factor for sporadic progressive neurodegenerative diseases. Parkinson's disease has been associated with exposure to the pesticide rotenone, a mitochondrial respiration inhibitor. We previously reported that intranasal administration of rotenone in mice induced dopaminergic (DA) neurodegeneration in the olfactory bulb (OB) and reduced olfactory functions. In the present study, we investigated the DA neurons in the brains of mice that were administered rotenone intranasally for an extended period. We found that the olfactory function of mice was attenuated by rotenone administration. Electrophysiological analysis of the mitral cells, which are output neurons in the OB, revealed that the inhibitory input into the mitral cells was retarded. In the immunohistochemical analysis, neurite degeneration of DA neurons in the substantia nigra was observed in rotenone-administered mice, indicating that rotenone progressively initiated the degeneration of cerebral DA neurons via the nasal route.

Intranasal administration of rotenone in mice attenuated olfactory functions through the lesion of dopaminergic neurons in the olfactory bulb

Many environmental chemicals are thought to affect brain function. It was reported that chemicals in the nasal cavity directly reach the brain through the connection between olfactory neurons and the olfactory bulb (OB). In this 'olfactory transport,' xenobiotics absorbed at the nasal mucosa reach the brain by bypassing some physical barriers and defenses, and thus olfactory transport is suspected to be a vulnerable mechanism of the brain against invasion threats of environmental chemicals. In this study, we focused on the neuronal toxicity of rotenone administered intranasally to mice. The results showed that the mice that were administered rotenone had attenuated olfactory functions. We also found that intranasally administered rotenone induced acute mitochondrial stress at the OB. The repeated administration of rotenone resulted in a decrease in the number of dopaminergic neurons, which are inhibitory interneurons in the OB. Taken together, our findings suggest that the inhalation of environmental toxins induces the neurodegeneration of cranial neurons through olfactory transport, and that olfactory dysfunction may be induced as an earliest symptom of neurodegeneration caused by inhaled neurotoxins.

Similar rate of information transfer on stimulus intensity in accessory and main olfactory bulb output neurons

Recently, evidence has accumulated that the vomeronasal system cooperates with the main olfactory system to process volatile cues that regulate the animal's behavior. This is contradictory to the traditional view that the vomeronasal system is quite different from the main olfactory system in the time scale of information processing. Particularly, the firing rate of mitral/tufted cells in the accessory olfactory bulb (MTAOB) is known to be significantly lower than that of mitral cells in the main olfactory bulb (MCMOB). To address this question of whether the low-frequency firing in MTAOB carries less information than the high-frequency firing in MCMOB in the early stages of stimulation, we compared MTAOB and MCMOB for their firing mechanisms and information transfer characteristics. A model computation demonstrated that the inherent channel kinetics of MTAOB was responsible for their firing at a lower frequency than MCMOB. Nevertheless, our analysis suggested that MTAOB were comparable to MCMOB in both the amount and speed of information transfer about depolarizing current intensity immediately after current injection onset (<200ms). Our results support a hypothesis of simultaneous processing of common cues in both systems.

Hard-diet feeding recovers neurogenesis in the subventricular zone and olfactory functions of mice impaired by soft-diet feeding

The subventricular zone (SVZ) generates an immense number of neurons even during adulthood. These neurons migrate to the olfactory bulb (OB) and differentiate into granule cells and periglomerular cells. The information broadcast by general odorants is received by the olfactory sensory neurons and transmitted to the OB. Recent studies have shown that a reduction of mastication impairs both neurogenesis in the hippocampus and brain functions. To examine these effects, we first measured the difference in Fos-immunoreactivity (Fos-ir) at the principal sensory trigeminal nucleus (Pr5), which receives intraoral touch information via the trigeminal nerve, when female adult mice ingested a hard or soft diet to explore whether soft-diet feeding could mimic impaired mastication. Ingestion of a hard diet induced greater expression of Fos-ir cells at the Pr5 than did a soft diet or no diet. Bromodeoxyuridine-immunoreactive (BrdU-ir) structures in sagittal sections of the SVZ and in the OB of mice fed a soft or hard diet were studied to explore the effects of changes in mastication on newly generated neurons. After 1 month, the density of BrdU-ir cells in the SVZ and OB was lower in the soft-diet-fed mice than in the hard-diet-fed mice. The odor preferences of individual female mice to butyric acid were tested in a Y-maze apparatus. Avoidance of butyric acid was reduced by the soft-diet feeding. We then explored the effects of the hard-diet feeding on olfactory functions and neurogenesis in the SVZ of mice impaired by soft-diet feeding. At 3 months of hard-diet feeding, avoidance of butyric acid was reversed and responses to odors and neurogenesis were recovered in the SVZ. The present results suggest that feeding with a hard diet improves neurogenesis in the SVZ, which in turn enhances olfactory function at the OB.

Polyubiquitination of the B-cell translocation gene 1 and 2 proteins is promoted by the SCF ubiquitin ligase complex containing βTrCP

B-cell translocation gene 1 and 2 (BTG1 and BTG2) are members of the BTG/Tob antiproliferative protein family, which is able to regulate the cell cycle and cell proliferation. We previously reported that BTG1, BTG2, Tob, and Tob2 are degraded via the ubiquitin-proteasome pathway. In this study, we investigated the mechanism of polyubiquitination of BTG1 and BTG2. Since the Skp1-Cdc53/Cullin 1-F-box protein (SCF) complex functions as one of the major ubiquitin ligases for cell cycle regulation, we first examined interactions between BTG proteins and components of the SCF complex, and found that BTG1 and BTG2 were capable of interacting with the SCF complex containing Cullin-1 (a scaffold protein) and Skp1 (a linker protein). As the SCF complex can ubiquitinate various target proteins by substituting different F-box proteins as subunits that recognize different target proteins, we next examined which F-box proteins could bind the two BTG proteins, and found that Skp2, β-transducin repeat-containing protein 1 (βTrCP1), and βTrCP2 were able to associate with both BTG1 and BTG2. Furthermore, we obtained evidence showing that βTrCP1 enhanced the polyubiquitination of both BTG1 and BTG2 more efficiently than Skp2 did, and that an F-box truncated mutant of βTrCP1 had a dominant negative effect on this polyubiquitination. Thus, we propose that BTG1 and BTG2 are subjected to polyubiquitination, more efficiently when it is mediated by SCFβTrCP than by SCFSkp2.

Link between the ubiquitin conjugation system and the ISG15 conjugation system: ISG15 conjugation to the UbcH6 ubiquitin E2 enzyme

ISG15 is a ubiquitin-like protein that is upregulated on treatment with interferon. ISG15 is considered to be covalently conjugated to cellular proteins through a sequential reaction similar to that of the ubiquitin conjugation system consisting of E1/E2/E3 enzymes: UBE1L and UbcH8 have been reported to function as E1 and E2 enzymes, respectively, for ISG15 conjugation. Several cellular proteins have been identified as targets for ISG15 conjugation, but the roles of ISG15 conjugation remain unclear. In this study, we found that UbcH6 and UbcH8, E2 enzymes for ubiquitin conjugation, are covalently modified by ISG15. We also found that UbcH6 is capable of forming a thioester intermediate with ISG15 through Cys131. We determined that the Lys136 residue near the catalytic site Cys131 is the ISG15 conjugation site in UbcH6. We isolated ISG15-modified and unmodified UbcH6 proteins, and analyzed their abilities to form thioester intermediates with ubiquitin. A ubiquitin thioester intermediate was detected in the case of unmodified UbcH6, but not in that of ISG15-modified UbcH6, strongly suggesting that ISG15 conjugation to UbcH6 suppresses its ubiquitin E2 enzyme activity. Thus, we provide evidence for a link between the ubiquitin conjugation system and the ISG15 conjugation system.

Incidental acute infarcts identified on diffusion-weighted images: a university hospital-based study

BACKGROUND AND PURPOSE

Pathogenesis of leukoaraiosis is incompletely understood and accumulation of small infarctions may be one of the possible sources of such white matter lesions. Thus, the purpose of this study was to identify the rate of incident infarction as depicted on diffusion-weighted images (DWIs) obtained from a general patient population.

MATERIALS AND METHODS

During the 4-year study period, a total of 60 patients (36 men and 24 women) had an incidental DWI-defined infarction without overt clinical symptoms suggestive of a stroke or a transient ischemic attack. All of the MR images were obtained by using a similar protocol on 2 identical 1.5T whole-body scanners. The patient's vascular risk factors, as well as the presence of white matter lesions (WMLs) on MR imaging and atheromatous changes on MR angiography, were assessed retrospectively. The incidental DWI-defined infarcts were also characterized in terms of their lateralization, lobe, and specific location.

RESULTS

A total of 16,206 consecutive brain MR images were done during the study period; the overall incidence of incidental infarcts was 0.37%. Most of these patients with an incidental infarct had vascular risk factors and WMLs on MR images. Most of these patients (80%) had a single lesion on DWI. A total of 88 lesions were identified; most were located in the white matter of the supratentorial brain, primarily in the frontoparietal lobes. There were also lesions involving the brain stem (n = 2). The lesions involving cerebrum were more commonly located in the right side (right to left = 52:34).

CONCLUSION

Small, DWI-defined acute brain infarctions can be found incidentally in an asymptomatic population; this finding may account, at least in part, for the pathogenesis of WMLs identified on MR imaging.

Multitensor tractography enables better depiction of motor pathways: initial clinical experience using diffusion-weighted MR imaging with standard b-value

BACKGROUND AND PURPOSE

The purpose of this work was to test the feasibility of using high angular resolution diffusion imaging (HARDI)-based multitensor tractography to depict motor pathways in patients with brain tumors.

MATERIALS AND METHODS

Ten patients (6 males and 4 females) with a mean age of 52 years (range, 9-77 years) were scanned using a 1.5T clinical MR unit. Single-shot echo-planar imaging was used for diffusion-weighted imaging (repetition time, 6000 ms; excitation time, 88 ms) with a diffusion-sensitizing gradient in 32 orientations and a b-value of 1000 s/mm(2). Data postprocessing was performed using both the conventional single- and multitensor methods. The depiction rate of the 5 major components of the motor pathways, that is, the lower extremity, trunk, hand, face, and tongue, was assessed.

RESULTS

Motor fibers on both lesional and contralesional sides were successfully depicted by both the single-tensor and multitensor techniques. However, with the single-tensor model, the depiction of motor pathways was typically limited to the fibers of trunk areas. With the multitensor technique, at least 4 of 5 major fiber bundles arising from the primary motor cortex could be identified.

CONCLUSION

HARDI-based multitensor tractography using a standard b-value (1000 s/mm(2)) can depict the fiber tracts from the face and tongue regions of the primary motor cortex.

Epidemiology of Epstein-Barr virus, cytomegalovirus, and Kaposi's sarcoma-associated herpesvirus infections in peripheral blood leukocytes revealed by a multiplex PCR assay

A multiplex polymerase chain reaction (PCR) has been developed for the simultaneous detection of Epstein-Barr virus (EBV), cytomegalovirus (CMV), and Kaposi's sarcoma-associated herpesvirus (KSHV) in a clinical sample. Primers of multiplex PCR were designed to amplify specific regions of the EBV EBNA1, CMV IE2, and KSHV LANA genes. This multiplex PCR assay was found to have detection sensitivities of 1-10 copies of purified viral DNA cloned into the plasmid. To assess diagnostic and pre-clinical applications with this method, we utilized KSHV-positive primary effusion lymphoma (PEL) cells, EBV-positive Burkitt's lymphoma cells, CMV-infected fibroblast cells, and clinically prepared peripheral blood leukocytes (PBLs) that had been infected with viruses. We found that this multiplex PCR assay has high sensitivity and specificity for simultaneous detection of EBV, CMV, and KSHV genomes in a single amplification from a clinical material. Using this multiplex PCR assay, we investigated the prevalence of EBV, CMV, and KSHV in PBL samples from normal Japanese randomly selected. KSHV, EBV, and CMV genomes were detected in samples from 2 (0.2%), 377 (39.5%), and 27 (2.8%) of the 953 blood donors, respectively. Interestingly, both EBV and CMV genomes were detected in samples from all KSHV-positive donors.

Antiproliferative proteins of the BTG/Tob family are degraded by the ubiquitin-proteasome system

BTG/Tob family proteins, which are characterized by similarities in their N-terminal BTG/Tob homology domains, control cell growth negatively. Among the BTG/Tob family members, BTG2/TIS21/PC3 proteins have been reported to have short lives and to be degraded by the proteasome. However, the mechanisms regulating the stabilities of other BTG/Tob family proteins have not yet been clarified. Here, we report that BTG1, Tob, and Tob2 proteins, as well as BTG2 protein, are degraded by the ubiquitin-proteasome system; the degradation of Tob protein in HeLa cells and the degradation of BTG1, BTG2, Tob and Tob2 proteins transiently expressed in HEK293 cells were inhibited by treatments with proteasome-specific inhibitors. Co-expression of BTG1, BTG2, Tob, or Tob2 protein with ubiquitin in HEK293 cells revealed specific multiubiquitination of each of the four proteins. Although the full-length and N-terminal truncated forms of BTG1, BTG2, Tob, and Tob2 proteins were unstable, the respective C-terminal truncated forms were found to be almost stable, suggesting that the C-terminal regions control the stabilities of BTG1, BTG2, Tob, and Tob2 proteins. In addition, it was found that the respective C-terminal regions confer instability on green fluorescent protein, a normally stable protein. Thus, it can be concluded that the C-terminal regions are necessary and sufficient to control the stabilities of BTG1, BTG2, Tob, and Tob2 proteins.

A case of diastematomyelia associated with myeloschisis in a hemicord

We report a case of myeloschisis on the right hemicord in a patient with diastematomyelia. The patient was a female neonate with myeloschisis visible at birth in the upper lumbar region. Radiological examination, including three-dimensional CT and MRI, clearly revealed a bony septum as well as the myeloschisis on the right hemicord, which enabled us to make a precise preoperative diagnosis of this complex anomaly. Closure of the myeloschisis and removal of the septum were successfully accomplished in one stage to prevent subsequent infection and neurological deterioration. The presence of combined diastematomyelia and myeloschisis is consistent with the hypothesis of an ontogenic basis of development and emphasizes the importance of early imaging for diagnosis in this complex anomaly.

Assembly of the 26S proteasome is regulated by phosphorylation of the p45/Rpt6 ATPase subunit

We investigated whether the assembly/disassembly of the 26S proteasome is regulated by phosphorylation/dephosphorylation. The regulatory complex disassembled from the 26S proteasome was capable of phosphorylating the p45/Sug1/Rpt6 subunit, suggesting that the protein kinase is activated upon dissociation of the 26S proteasome or that the phosphorylation site of p45 becomes susceptible to the protein kinase. In addition, the p45-phosphorylated regulatory complex was found to be incorporated into the 26S proteasome. When the 26S proteasome was treated with alkaline phosphatase, it was dissociated into the 20S proteasome and the regulatory complex. Furthermore, the p45 subunit and the C3/alpha2 subunit were cross-linked with DTBP, whereas these subunits were not cross-linked by dephosphorylating the 26S proteasome. These results indicate that the 26S proteasome is disassembled into the constituent subcomplexes by dephosphorylation and that it is assembled by phosphorylation of p45 by a protein kinase, which is tightly associated with the regulatory complex. It was also revealed that the p45 subunit is directly associated with the 20S proteasome alpha-subunit C3 in a phosphorylation-dependent manner.

[Relationship of postoperative residual air and recurrence in chronic subdural hematoma]

The possibility exists that residual air after surgery is one cause of recurrence of chronic subdural hematoma. We have devised a new simple method which decreases postoperative residual air, using external drainage and an endoscope. First, we make endoscopic observations of the inner aspect of the hematoma cavity. Then, we insert external drainage apparatus into the most frontal area of the hematoma cavity, we regard this location as the most appropriate place to ensure most effective drainage. The present study included 37 chronic subdural hematomas in 32 patients who had been treated between January and December, 1999. Their ages ranged from 48 to 86 years old, with an average of 72 years. Insertion of external drainage in the most frontal area of the hematoma cavity was successfully achieved in 27 (73%, Group I) out of 37 cases and resulted in no recurrence. In the remaining 10 hematomas (27%, Group II), external drainage was not able to be inserted in the most frontal area, and four hematomas (40%) had recurrence (p < 0.01 vs Group I). Insertion in the most frontal area of the hematoma cavity decreases residual air after surgery, and may be effective for the prevention of recurrence of chronic subdural hematoma.

Arterial relaxation mediated by endothelium-derived hyperpolarizing factor in hypertension induced by chronic inhibition of nitric oxide synthesis

The aim of this study was to evaluate arterial relaxation mediated by endothelium-derived hyperpolarizing factor (EDHF) during chronic inhibition of nitric oxide (NO) synthase. We measured the isometric tension of isolated mesenteric arteries of Wistar rats administered Nomega-nitro-L-arginine methyl ester (L-NAME, 100 mg/Kg/day) for 3 weeks. Relaxation to acetylcholine (ACh) was reduced in L-NAME treated rats (maximum relaxation, 52% versus 79% ). After acute superfusion of 1x10(-4) M L-NAME, half the relaxation was inhibited in controls, while the relaxation was not changed in L-NAME treated rats. In contrast, relaxation to nitroprusside was normal in L-NAME treated rats. Superfusion of 1x10(-6) M apamin, which inhibits the effects of EDHF, reduced the relaxation. The relaxation inhibited by apamin was not significantly different between the two groups. These findings suggested that in endothelial cells, the synthesis of EDHF is unchanged during a chronic deficiency of relaxation influence of NO.

Significance of hearing preservation in acoustic neuroma surgery

In the past 10 years, 43 patients with acoustic neuroma have been operated on by the middle cranial fossa approach. In all cases, meticulous care was taken to preserve the cochlear function regardless of the degree of preoperative hearing disorder. Thirty-nine of 43 patients had various degrees of residual hearing, hearing was preserved in 16 of these (41%). The best result was obtained in patients with a tumor located less than 1 cm from the porus. The hearing preservation rate was 64% (11/17). The patients recovered hearing acuity quite well, especially at low frequencies in 2 cases who had a pure tone hearing level of more than 50 dB and less than 50% of speech discrimination. These 2 cases had a history of sudden deafness that was intractable 5 months preoperatively. Thus it is not correct to set certain criteria for hearing preservation for patients whose preoperative hearing may not be serviceable.

[Superficial siderosis appeared in a case of suprasellar embryonal carcinoma]

A case of superficial siderosis that appeared in a case of suprasellar embryonal carcinoma is reported. A 24-year-old man presented polydipsia and vertigo. MRI revealed a suprasellar tumor. The tumor contained high intense spots on T1-weighted images, suggesting intratumoral hemorrhage. He underwent a surgery, which proved it as embryonal carcinoma pathologically. Cerebrospinal fluid was xanthochromic at surgery, suggesting terminal hemorrhage. After surgery, he received a total dose of 56 Gy of irradiation. Tumor decreased in size and symptoms improved. However, he presented occipital headache 7 months after surgery. MRI showed disseminated tumors in the subarachnoid spaces. He received irradiation for the whole spine and adjuvant chemotherapy. During treatment, MRI demonstrated low signals on the surface of the brain stem, suggesting the superficial siderosis. The lesions spread to the surface of the cerebellum and tentorium cerebelli. Superficial siderosis is characterized by the deposition of hemosiderin in the leptomeninges, cranial nerves and spinal cord. The etiology of the hemosiderin deposition is thought to be chronic or recurrent bleeding into subarachnoid space. Experimentally, similar lesions have been produced in the animals following intrathecal injection of blood or hemolysed red cells. In the literature, MRI demonstrated a rim of marked hypo-intensity on T2-weighted images, consistent with hemosiderin deposits, on the surface of cerebellum and brain stem. Gradient-echo sequences have been more sensitive than T2-weighted images of spin echo sequences. In the present case, the superficial siderosis seems to be due to chronic tumoral hemorrhage. This phenomenon could be related to chemotherapy using CDDP and etoposide.

Development of a huge varix following endovascular embolization for cerebellar arteriovenous malformation. A case report

We report on the case of a huge varix that developed after the endovascular embolization of a cerebellar arteriovenous malformation (AVM) with a single drainer. A 21-year-old male presented with trigeminal neuralgia which was caused by the dilated drainer of the AVM. A varix was found at the basal vein of Rosenthal 2 months after an initial stage of embolization with polyvinyl alcohol particles; it diminished after the surgical extirpation of the AVM. The varix formation might have been facilitated by the stenosis in the vein of Galen and by the dynamic changes that followed the embolization. This rare complication should be kept in mind when embolization is performed for AVMs with impaired venous outlets.

Fractional Ca2+ release from the endoplasmic reticulum activates Ca2+ entry in freshly isolated rabbit aortic endothelial cells

The purpose of the present investigation was to examine the correlation between rates of endoplasmic reticulum (ER) depletion and activation of store operated channels (SOC) in freshly isolated rabbit aortic endothelial cells. We investigated the effects of 10 microM cyclopiazonic acid (CPA), 10 microM ryanodine, and 10 mM caffeine on the rate of Ca2+ depletion from the ER and on Ca2+ and Mn2+ influx using fura-2 fluorescence. We observed that the spontaneous loss of the ACh-sensitive pool is slow. Activation of ryanodine receptors (caffeine, ryanodine) or inhibition of the ER Ca2+ pump (CPA) increased the rate of Ca2+ loss from the ACh-sensitive pool. CPA stimulated Mn2+ influx, while caffeine and ryanodine did not. Our results show non linear correlation between ER depletion and activation of divalent cation entry. In the case of CPA, less than 20% depletion of the ACh sensitive store was required for full activation of SOC, while caffeine and ryanodine deplete over 50% of the ACh sensitive store without activating any influx. These data suggest that only a small compartment of the ER is involved in regulation of Ca2+ entry.

Increased Ca2+ sensitivity of contractile elements via protein kinase C in alpha-toxin permeabilized SMA from young spontaneously hypertensive rats

OBJECTIVE

The purpose of the present investigation was to examine the Ca2+ sensitivity of the contractile elements via protein kinase C (PKC) in superior mesenteric artery (SMA) from young (5-6 weeks old) spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY).

METHODS

Staphylococcal aureus alpha-toxin, which produces pores in the plasma membrane too small to allow passage of proteins such as PKC, was used to investigate the signal transduction system in vascular smooth muscle cells. We investigated the Ca2+ sensitivity of the contractile apparatus via PKC in intact and alpha-toxin skinned SMA from young SHR and WKY.

RESULTS

In intact SMA, high K+ responses were not different between SHR and WKY. However, phorbol 12,13-dibutyrate (PDBu, a PKC activator) augmented high K(+)-evoked contractions and PKC inhibitors, such as 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7) and calphostin C, suppressed them more in SHR as compared with WKY. In alpha-toxin skinned SMA, the [Ca2+]i-force relationship curve was not significantly different between SHR and WKY. However, PDBu augmented [Ca2+]i-evoked contractions and PKC inhibitors suppressed them more in SHR than in WKY.

CONCLUSION

These results suggest that the Ca2+ sensitivity of the contractile elements via PKC is significantly greater in prehypertensive SHR than in age-matched WKY. This abnormality in small muscular arteries may be involved in the pathogenesis of hypertension in SHR.

Preliminary results with technetium-99m MIBI SPECT imaging in patients with brain tumors: correlation with histological and neuroradiological diagnoses and therapeutic response

SPECT using Tc-99m MIBI was performed in patients with brain tumors in order to determine Tc-99m MIBI uptake in brain tumors and to evaluate the efficacy of MIBI imaging in the assessment of treatment response. A MIBI uptake index was calculated on SPECT imaging. All tumors with a MIBI-index higher than 7.5 were malignant. In the tumors evaluated before and after radiochemotherapy, the MIBI-index immediately following therapy correlated with treatment response 2 months after therapy. Thus, semiquantitative assessment using Tc-99m MIBI SPECT imaging may be useful in the evaluation of treatment response.

[Laparoscopic retrieval of a dislocated ventriculoperitoneal shunt catheter: report of three cases and a review of the literature]

Described are 3 cases of a disconnected ventriculoperitoneal shunting system that was successfully retrieved by using a laparoscopic procedure, with a review of the literature. All patients had symptoms of increased intracranial pressure. Roentgenograms showed disconnection of a ventriculoperitoneal shunt catheter at the connecting device and its migration into the peritoneal cavity. A laparoscope was introduced into the peritoneal cavity using the double puncture procedure and the catheter was extracted in less than 15 minutes. The use of a laparoscope enabled exploration of the entire space of the cavity without any large laparotomy incision. Furthermore, the laparoscopic procedure also easily enabled introduction of a replaceable ventriculoperitoneal shunt catheter into the appropriate portion in the cavity and confirmed the CSF flow into the cavity. Because catheters which have migrated into the cavity might cause an acute abdomen, it is important that they should be removed as soon as possible. It should be kept in mind, during the procedures of extracting catheters, that the inner absorptive surface of the peritoneal cavity must be preserved as much as possible. In this regard, laparoscopic retrieval of disconnected shunt catheters is a promising method.

Unilateral acoustic neuroma in childhood

Three cases of unilateral acoustic neuroma in childhood that are associated with neither neurofibromatosis type 1 nor type 2 were reported. All three cases had a hearing disorder as an initial symptom. Two of them had a large neuroma and had considerable abnormal findings in neurootological examinations, and one case with an intracanalicular tumor showed a unilateral progressive sensorineural hearing loss that had no response to steroid administration. Surgical removal of the tumor was carried out for these cases. Different approaches were used in each case; suboccipital approach, one-stage suboccipital and middle fossa approach, and middle fossa approach. Although the facial nerve functions were fairly well maintained, hearing preservation could not be attained in all. Papers dealing with this tumor were reviewed, and certain characteristics of cases with acoustic neuroma in childhood were discussed.

Inhibition of methionine uptake by cis-diamminedichloroplatinum (II) in experimental brain tumors

cis-diamminedichloroplatinum (II) (CDDP) has been used both alone and in combination with other chemotherapeutics for cancer chemotherapy. Although CDDP acts primarily on DNA, it can also act at the tumor-cell membrane to inhibit methionine transport. The latter mechanism of CDDP is reported to have an important role as a chemical modulator in enhancing chemotherapeutic effects of 5-fluorouracil in tumor cells. We report here the effects of CDDP on methionine uptake in an in vivo brain-tumor model. C6 brain-tumor cells were stereotactically inoculated in the right basal ganglia of 6-week-old male Sprague-Dawley rats. Ten days after the inoculation, autoradiographic images were obtained using (14C-methyl)-L-methionine. The tracer uptake, represented as differential absorption ratio (DAR) and an acid-insoluble fraction (AIF), was measured in both brain tumors and normal brain with or without an intravenous injection of CDDP. The tumor/non-tumor DAR and AIF decreased significantly (P < 0.01, as determined by the Mann-Whitney U-test) after CDDP treatment, whereas the non-tumor DAR and AIF remained almost unchanged. These findings indicate that CDDP inhibits methionine uptake selectively in brain-tumor tissue and may therefore be a potent chemical modulator in the chemotherapy of brain tumors.

Intramedullary spinal cord germinoma: case report and review of the literature

We discuss the case of a patient with a recurring intramedullary spinal cord germinoma of the lower thoracic spinal cord, which was successfully excised. A primary intramedullary spinal cord germinoma is very rare, and only four other cases have been reported in the literature. All five cases are reviewed regarding the appearance of the germinomas, their neuroradiological features, and their histopathological findings. We also discuss treatment choices for germinomas of the spinal cord.

Increased calcium sequestration by sarcoplasmic reticulum in small muscular arteries in young spontaneously hypertensive rats

1. Sarcoplasmic reticulum (SR) in small resistance arteries plays a role in the regulation of the cytosolic free calcium concentration by sequestration of calcium from cytoplasm. 2. To examine the contribution of calcium (Ca2+) sequestration by the SHR to both contraction and relaxation in young spontaneously hypertensive rats (SHR), we measured evoked tension before and after depletion of SR Ca2+ stores in the rings of the first branch of superior mesenteric artery in 5 week old SHR and age-matched Wistar-Kyoto (WKY) rats. Contractile responses were induced by 40 mmol/L potassium and 10 mmol/L caffeine before and after the treatment with ryanodine or thapsigargin, which depletes SR calcium stores. 3. The magnitude of potassium-induced contraction was almost the same in both strains. 4. Ryanodine and thapsigargin did not affect the resting tension and almost decreased caffeine-induced contraction in both strains. 5. After the treatment with ryanodine or thapsigargin, the magnitude and the rate of potassium-induced contraction were augmented greatly in SHR, but not in WKY. 6. The relative relaxation rate after exposure of potassium was significantly slowed in SHR by ryanodine or thapsigargin, but only slightly in WKY. 7. These results suggest that Ca2+ sequestration by the SR in SHR was greater than in WKY. Therefore, it is concluded that SR plays an important role in preventing the development of hypertension in SHR via a buffering effect on the elevation of cytosolic free Ca2+.

Blood flow and metabolism of central neurocytoma: a positron emission tomography study

BACKGROUND

New World Health Organization classifications have categorized central neurocytomas as neuronal tumors. The differential diagnosis between central neurocytomas and other tumors is important for selection of the optimal therapy modality for the management of intraventricular tumors. To characterize the pathophysiology and proliferating activity of central neurocytoma accurately, cerebral blood flow and metabolism in five patients with central neurocytoma were studied using positron emission tomography (PET).

METHODS

Tracers used for the present study included C15O2, C15O, 15O2, and 18F-fluorodeoxyglucose (FDG). Regional cerebral blood flow (rCBF), cerebral blood volume (rCBV), oxygen extraction fraction (rOEF), cerebral metabolic rate of oxygen (rCMRO2), and cerebral metabolic rate of glucose (rCMRGl) were quantitatively analyzed in tumor lesions and the contralateral gray matter. Four patients with central neurocytoma underwent a complete PET study, including all circulatory and metabolic parameters; one patient was studied with 11C-methyl-L-methionine and FDG tracers.

RESULTS

Tumor rCBF and rCBV were higher than comparable values in the contralateral gray matter in three of four patients. This high level of perfusion corresponds to angiographic findings that show intense tumor staining in tumors fed by perforated arteries. Tumor rOEF and rCMRO2 were significantly lower than corresponding values in the gray matter (rOEF, P < 0.01; rCMRO2, P < 0.05 by Student's t test). Tumor rCMRGl ranged from 2.68 to 6.26 mg/100 ml/minutes and did not exceed contralateral gray matter values in any of the five patients. Tumor rCMRGl was significantly lower (P < 0.02) than the gray matter rCMRGl. One tumor exhibited a relatively high value of rCMRGl (comparable to gray matter rCMRGl), and increased in size 4 months after partial resection. No other tumors appeared during postoperative follow-up periods that ranged from 4 to 135 months.

CONCLUSIONS

Circulation and metabolism parameters measured by PET offer insight into the biologic characteristics of central neurocytoma. Tumor rCMRGl may be an indicator of the proliferating activity in central neurocytoma.

White matter hyperintensity in neurologically asymptomatic subjects

Recent advances in magnetic resonance imaging (MRI) technology have had a great impact on the delectability of minute, asymptomatic lesions of the central nervous system. The clinical significance and treatment modes of these lesions, such as white matter hyperintensity (WMH) lesions detected by T2 MRI, remain controversial. To address these problems, we retrospectively evaluated WMH lesions in relation to clinical parameters for 240 neurologically asymptomatic persons who had visited a hospital for a medical check-up of the brain. Proton and T2-weighted MRI were obtained using a 0.5 T superconducting MR imager using the spin echo technique with a repetition time (TR) of 2800 msec. An echo delay times (TE) of 40 msec was used for the proton MRI, and a TE of 100 msec was used for the T2-weighted MRI. The images were visually analyzed according to a four-point grading system. The MRI findings were correlated with clinical parameters including age, gender, presenting symptoms, and hypertension. The overall frequency of WMH increased with age. Grades 2 and 3 of WMH were more frequent in aged persons, whereas the occurrence of grade 1 WMH remained relatively constant across age groups. Based on multiple regression analysis, age was the most significant variable influencing the frequency of WMH, followed by hypertension. These results imply that WMH lesions may simply be a phenomenon of aging, or may be an indicator of prepathologic state in an ischemic brain.

Laparoscopic retrieval of disconnected ventriculoperitoneal shunt catheters: report of two cases

Two patients previously treated with ventriculoperitoneal shunt for hydrocephalus had the distal catheters disconnected, and they migrated to the free peritoneal cavity. The signs and symptoms of increased intracranial pressure occurred as a result of mechanical failure of the shunt system. Both patients successfully underwent a laparoscopic retrieval of the catheters using endoscopic grasping forceps, and revision of the ventriculoperitoneal shunt by inserting the new catheters into the peritoneal cavity was performed through a small entrance for the laparoscope. Recently, conventional laparotomy has been often replaced by laparoscopic surgery, and general surgeons are well familiar with the laparoscopic procedures. The significant advantage of this procedure is the ability to explore the entire peritoneal cavity for both diagnosis and treatment, and it is by far a less invasive approach than conventional laparotomy. The present report describes the laparoscopic procedure for removal of the migrated catheters and discusses its advantages over conventional laparotomy.

Role of protein kinase C in relationship between Ca2+ and contractile elements in rat alpha-toxin-permeabilized mesenteric artery

Phorbol ester, which activates protein kinase C (PKC), modulates vasoconstrictor-induced tension in vascular smooth muscle. Recently, Staphylococcal aureus alpha-toxin, which produces too small pores in the plasma membrane to allow passage of proteins, such as PKC, is used to investigate the signal transduction system in vascular smooth muscle cells. In order to elucidate the role of PKC on vascular smooth muscle contraction, we examined whether PKC activation influences the relationship between intracellular Ca2+ ([Ca2+]i) and tension in Wistar rat superior mesenteric artery (SMA) using vascular smooth muscle permeabilized with Staphylococcal alpha-toxin. [Ca2+]i was clamped at specified values (10(-8.5)-10(-4) mol/L) using EGTA-Ca2+ buffer. In alpha-toxin non-treated rings of SMA, isometric tension was evoked by 10 mmol/L caffeine and 10-30 mmol/L external potassium (high K+) in the absence or presence of phorbol 12, 13-dibutyrate (PDBu), a PKC activator, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7), and staurosporine (PKC inhibitors). PDBu significantly augmented caffeine- and high K(+)-evoked contractions. H-7 and staurosporine significantly attenuated caffeine- and high K(+)-evoked contractions augmented by PDBu. Moreover, H-7 significantly suppressed high K(+)-induced contraction in the absence of PDBu. In alpha-toxin permeabilized artery, PDBu shifted the [Ca2+]i-force relationship curve to the left. These results suggest that PKC activates vascular smooth muscle contraction by increasing the sensitivity of the contractile apparatus to Ca2+.

Vascular malformations of the brain in hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber disease)

Six patients with vascular malformation of the brain in hereditary hemorrhagic telangiectasia (HHT) were reviewed to determine clinical and radiographic characteristics of these lesions. There were two patients with arteriovenous fistula (AVF), three with arteriovenous malformation (AVM), and one with multiple AVMs associated with AVF. Seizures were the most common presenting symptom (seen in three patients), and two of them had intracerebral hematomas (ICH). In the remainder, the malformations were incidentally found in the course of evaluation of other diseases. Their locations were variable, but the majority was superficially confined to the cerebral cortex. Arterial supply was from mostly one feeding artery that was a cortical branch of either anterior, middle, or posterior cerebral artery. In six of nine malformations, the venous drainage was through a superficial cerebral vein into either the superior sagittal sinus or transverse sinus. Direct surgery was done on two patients with ICH, artificial embolization on one, and stereotactic radiosurgery on one. The cerebral vascular malformations in HHT are not infrequent, and in particular the importance of computed tomography and cerebral angiography should be recognized in patients with pulmonary AVF associated with HHT.

[A study on the incidences of streptococcal infectious diseases in the regional surveillance informations of infectious diseases in Japan (2nd report)]

The incidences of streptococcal infectious diseases in the regional surveillance informations of infectious diseases of 47 prefectures were compared with each other by the ratios of number of patients with streptococcal infectious diseases, exanthema subitum and varicella to the populations of surveyed age groups, respectively. It was estimated that although there were almost no regional differences in the ratios of exanthema subitum and varicella, the ratios of streptococcal infectious diseases were high in Hokkaido, Akita, Yamanashi, Shiga and Ehime Prefectures, respectively, and was low in Okinawa Prefecture. The corrected incidences of number of patients with streptococcal infectious diseases, calculated on the basis of the ratios of exanthema subitum and/or varicella, were also high in the regions of Hokkaido, Akita, Iwate, Nagano, Yamanashi, Gifu, Shiga, Okayama and Ehime Prefectures, respectively, and were low in the regions along the Pacific from the southern Tohoku (northern Japan) through a part of the Shikoku Island and the Sea of Japan from the Hokuriku (central Japan) through the Kyushu Island, and the regions of Nara and Okinawa Prefectures, respectively. The climate in the regions with high corrected incidence belonged to the Tohoku-Hokkaido, the Central Highlands and the Seto Inland Sea types, respectively. On the other hand, the regions with low corrected incidence belonged to the Tokai-Kanto, the Nankai (southern sea of Japan), the Hokuriku-Sanin, the Kyushu and the Okinawa climate types, respectively.

[Ventriculoperitoneal shunts with the use of pressure-adjustable valve in the management of hydrocephalus]

Sixteen patients with hydrocephalus of varied etiology who underwent ventriculo-peritoneal shunts utilizing pressure-adjustable valves were reviewed, and the usefulness of the pressure-adjustable valve in the management of hydrocephalus was evaluated. Before shunting all patients had CT evidence of hydrocephalus with Evans' Index greater than 30%. High-, medium- and low-pressure settings were chosen in 3, 11 and 2 patients respectively, according to the CSF pressure as measured during lumber puncture or ventricular drainage. Following the shunting procedures with programmable pressure valves, hydrocephalus was alleviated with Evans' Index being 27% on the average, as evaluated by CT scans. Such clinical symptoms as disturbed consciousness, dementia and increased intracranial pressure all subsided. There were no mortality, infection or revision during the follow-up period of 5 to 16 months. Of particular note was that, among these 16 cases, there were three illustrative cases in which programmable pressure valves were found useful in coping with newly developed subdural effusion and low-intracranial-pressure syndrome, by manually adjusting the valves to higher pressure settings.

[Chemotherapeutic strategy in rat brain tumor cells resistant to ACNU using an in vitro colony formation assay]

Nitrosourea compounds have been widely used in the chemotherapy of malignant brain tumors, because of their blood-brain barrier permeability. However, drug resistance to nitrosoureas has been recently a major concern. Using an in vitro colony formation assay, intrinsic and acquired resistances to an anticancer nitrosourea, 1-(4-amino-2-methyl-5-pyrimidinyl) methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU), were analyzed in rat 9L and C6 glioma cells. 9L and C6 cells were treated with varying doses of ACNU for 2 hours. Ten days after, the cells were fixed and stained with crystal violet. Colonies consisting more than 50 cells were counted. The survival fraction following treatment is the ratios of colony efficiency of treated cells to the colony efficiency of untreated control cells. The dose-response curve for ACNU indicated the existence of a shoulder (Dq, quasithreshold dose) at doses and an exponential cell-killing at higher doses with D0(37% survival dose). Based on dose-response curves corresponding to multitarget single-hit model, 9L cells showed 7.4 microM, 2.9 microM, and 14 microM at Dq, D0, and SD10 (10% survival dose) values, respectively, whereas C6 cells showed respective values of 6.4 microM, 30 microM, and 75 microM. 9L cells had significantly less intrinsic resistance to ACNU than C6 cells at the p less than 0.005 level by a covariance analysis of the curves. As with changes of drug susceptibility after ACNU treatment, both parent cells were treated every other day (1, 5, and 10 repeated times) with various doses up to approximately 1% survival dose of the parent cells.(ABSTRACT TRUNCATED AT 250 WORDS)

[Circumvention of ACNU-resistance in rat glioma cells by pretreatment with O6-methylguanine]

The chemotherapy of malignant brain tumors has been, only partially successful yet. Recently major concern is drug resistance, one of possible mechanisms of such drug resistance stems from inducible repair enzyme, especially in case of chloroethylnitrosoureas as ACNU or BCNU. We examined the changes of acquired resistance to ACNU in rat glioma cells by pretreatment with O6-methylguanine, which is a substrate for O6-methylguanine methyltransferase. ACNU-resistant (9L/AC) cells had established after 10 times treatments of ACNU. 9L/AC cells were pretreated with 2 mM O6-methylguanine for 2 hours, and subsequently challenged with increasing doses of ACNU for 2 hours. In vitro colony formation assay the survival fraction of 9L and 9L/AC cells ranged from 0.39 to 0.63 by 2-hour reaction of 1-3 mM O6-methylguanine. Based on the dose-response curve for ACNU in 9L/AC cells, by O6-methylguanine pretreatment (2 mM), ACNU-resistance decreased markedly to one-third, one-fifth, and one-two hundredth at 12, 24, 36 microM ACNU, respectively. In contrast, the survival of 9L cells against ACNU was similar under O6-methylguanine pretreatment or nontreatment condition. Therefore, ACNU-resistance is considerably related to DNA repair enzyme induction, and the substrates may potentiate the cell-killing effect of ACNU in the resistant glioma cells.

[Analysis of DNA damage induced by nitrosourea derivatives in rat brain tumor cells using a sequencing procedure]

DNA damages caused by various anticancer nitrosourea compounds such as ACNU and MCNU were studied. Reiterated fragments of 167 and 203 base pairs (bp) were obtained after Hind III and Hae III restriction endonuclease digestion of 9L rat brain tumor DNA. The end-labeled reiterated fragments were reacted with ACNU and MCNU, which resulted in the scission breaks corresponding to the locations of guanine on an extended Maxam-Gilbert sequencing gel. Subsequent piperidine hydrolysis yielded scission products more frequently. These results indicate that nitrosoureas such as ACNU and MCNU generate DNA scission breaks and/or alkali-labile sites preferentially at the position of guanine moieties in rat brain tumor DNA.