Comparison of neurological outcomes following witnessed out-of-hospital ventricular fibrillation defibrillated with either biphasic or monophasic automated external defibrillators.

BACKGROUND: Biphasic waveform defibrillation results in higher rates of termination of fibrillation than monophasic waveform defibrillation but has not been shown to improve survival outcomes. OBJECTIVE: To compare the effectiveness of a biphasic automated external defibrillator (AED) with a monophasic AED for witnessed out-of-hospital cardiac arrest (OHCA) due to ventricular fibrillation (VF). METHODS: In a prospective population-based cohort study, adults with witnessed VF OHCA were treated with either monophasic or biphasic waveform AED shocks. The primary outcome measure was neurologically favourable 1-month survival, defined as a Cerebral Performance Categories score of 1 or 2. RESULTS: Of 366 adults with witnessed OHCA of presumed cardiac aetiology, 74 (20%) had VF. Termination of VF with the first shock tended to occur more frequently after biphasic AED shocks (36/44 (82%) vs 20/30 (67%), p = 0.14). Return of spontaneous circulation (ROSC) occurred more frequently after biphasic AED shocks (29/44 (66%) vs 8/30 (27%), p = 0.001). Neurologically favourable 1-month survival was also more frequent in the biphasic group (10/44 (23%) vs 1/30 (3%), p = 0.04). The median time interval from the first shock to the second shock was 67 s in the monophasic group and 24 s in the biphasic group (p = 0.001). CONCLUSIONS: Treatment with biphasic AED shocks improved the likelihood of ROSC and neurologically favourable 1-month survival after witnessed VF compared with monophasic AED shocks. In addition to waveform differences, a shorter time interval from the first shock to the second shock could account for the better outcomes with biphasic AED.

Structure-based design and characterization of exocyclic peptidomimetics that inhibit TNF alpha binding to its receptor.

Exocyclic small peptidomimetics corresponding to three critical binding sites of tumor necrosis factor (TNF)-receptor(I) have been designed based on atomic features deduced from the crystal structures of TNF alpha and the TNF beta/TNF-receptor(I) complex and a model of an anti-TNF alpha monoclonal antibody. TNF alpha antagonistic activities were evaluated by binding assays using soluble receptor or intact receptor on cells as well as an apoptosis/cytotoxicity assay. The most critical interaction site for rational design of peptidomimetics was localized to the loop1/domain3 of the TNF-receptor. The best antagonist showed 5 microM inhibition in the binding assay. Biologically, the mimetics inhibited TNF alpha-mediated apoptosis.

Determination of a putative recombinogenic human hepatitis B virus sequence and its binding cellular protein.

Previously, we reported that C4BglII196, a 196-base pair subgenomic fragment of hepatitis B virus (HBV) covering its precore region, enhances in vitro recombination in the presence of extracts from actively dividing cells (Hino, O., et al. Proc. Natl. Acad. Sci. USA, 88:9248-9252, 1991). The results indicated that HBV may play some role in causing genomic instability during chronic hepatitis. In the present study, we showed that 15AB, a 60-base pair subgenomic fragment of HBV DNA (nucleotides 1855-1914) within C4BglII196 is indispensable for enhancement of in vitro recombination, using the mouse leukemia cell 70Z/3, as the cellular extract source. 15AB, thought to be the encapsidation signal of HBV pregenomic RNA and U5-like retrovirus long terminal repeat, was found to bind specifically to an approximately 100 kDa protein of 70Z/3 by southwestern blotting. Production of a mutation in the 15AB region decreased both its binding activity to 100 kDa protein and the in vitro recombination activity. Our present results thus suggest that 15AB might be a recombinogenic sequence and the 100-kDa protein may be a putative recombinogenic protein in eukaryotes, triggering genomic instability and facilitating carcinogenesis.

BRCA1 binds c-Myc and inhibits its transcriptional and transforming activity in cells.

c-Myc, a proto-oncogene that is implicated in tumorigenesis, embryonic development and apoptosis, can physically associate with BRCA1. We have found that BRCA1 interacts with c-Myc in yeast, in in vitro assays and in mammalian cells. Endogenous interactions between BRCA1 and c-Myc were also observed. Efficient BRCA1-Myc association requires the intact helix-loop-helix region of c-Myc, a motif involved in Myc-Max dimerization. BRCA1 does not however bind to Max. Our studies revealed that BRCA1 represses Myc-mediated transcription while having no effect on some other transcriptional activities. Furthermore, BRCA1 reverses the phenotype of embryonic fibroblasts transformed by the activation of Myc and Ras, but only minimally affects the transformed phenotype induced by SV40 virus. These data indicate that BRCA1 may function as a tumor suppressor by regulating the behavior of c-Myc and provide a molecular explanation for some of the effects of the BRCA1 gene product.

Relationship of p215BRCA1 to tyrosine kinase signaling pathways and the cell cycle in normal and transformed cells.

We have analysed the relationship of the products of two genes, neu and BRCA1, known to be important in human breast cancer. Highly specific antibodies that recognized both the rodent and human form of the BRCA1 gene product (Mr 215 kDa, p215BRCA1) were developed to facilitate these efforts. p215BRCA1 was identified as a tyrosine phosphorylated protein primarily localized in the nucleus of several breast cancer cell lines. In transformed murine and human cells, levels of p215BRCA1 tyrosine phosphorylation were inversely correlated with the activity of the erbB family receptor-tyrosine-kinases and with the transformed growth features of these cells. Regulation of p215BRCA1 tyrosine phosphorylation was also related to events in the cell cycle. Increased levels of p215BRCA1 phosphotyrosine content were observed in NIH3T3 cells arrested at the G2/M transition. These findings indicate that the products of BRCA1, neu, and erbB breast cancer genes participate in a common or shared signaling pathway important in cell growth and its regulation.

Fas- and perforin-independent mechanism of cytotoxic T lymphocyte.

Cytotoxic T lymphocytes (CTLs) play an important role in elimination of virus-infected cells (1). Recent studies revealed at least two distinct mechanisms that CTLs utilize to destroy their target cells. Both mechanisms induce target cell apoptosis specifically and directionally, but these processes are totally different. One is pore formation on target cell membrane by perforin secreted from CTLs (perforin-granzyme pathway), and the other is ligation of Fas, which is expressed on the surface of target cells and Fas ligand, on the surface of CTLs (Fas-FasL pathway) (2). Here we review our work and describe CTL clones that have novel lytic mechanisms derived from CD4-CD8- lymph node cells of gld mice.

beta-catenin mutations are absent in hepatocellular carcinomas of SV40 T-antigen transgenic mice.

beta-catenin mutations have been found not only in melanoma and prostatic carcinoma but also in hepatocellular carcinomas in human, c-myc, H-ras genes transgenic mice and chemically-induced models. We investigated beta-catenin mutations in human hepatocellular carcinomas (HCCs), Hep G2 cell line and HCCs in SV40 T-antigen transgenic mice, in order to examine whether beta-catenin mutations are frequently observed in HCC in general. We found a point mutation of beta-catenin in one of nine HCCs in human and a deletion of it in Hep G2 cell line. However, we found no mutation in HCC in SV40 TG mice liver.

VCP, a weak ATPase involved in multiple cellular events, interacts physically with BRCA1 in the nucleus of living cells.

BRCA1, a breast/ovarian cancer susceptibility gene, undergoes mutations in as many as 50% of familial breast tumors. Recent studies indicate that BRCA1 may be involved in DNA damage repair. Here, we demonstrate that the BRCA1 protein physically associates with valosin-containing protein (VCP), a member of the ATPases associated with a variety of cellular activities (AAA) superfamily. In vitro studies revealed that VCP, via its N- terminal region, binds to amino acid residues 303-625 in the BRCA1 protein. Although found predominantly in the cytoplasm and, less abundantly, in the nucleus, VCP can be translocated from the nucleus after stimulation with epidermal growth factor. Collectively, our results suggest that VCP, by binding to BRCA1, participates in the DNA damage-repair function as an ATP transporter, possibly facilitating the transcription-coupled repair.

Intracellular measurement of Na activity using neutral carrier Na ion-selective microelectrode.

To measure intracellular Na+ activities, a double-barreled Na ion-selective microelectrode was constructed with a neutral carrier Na+ ligand (ETH 227). The slope constant and detection limit were 56 mV and 3-5 mM, respectively, the selectivity of Na+/K+ being 40-50. In the bullfrog, the cell Na+ was 14.4 mEq/liter for the proximal tubule and 12.6 mEq/liter for the sartorius muscle.

Intrahepatic lymphocyte subpopulations and HLA class I antigen expression by hepatocytes in chronic hepatitis C.

The lymphocyte subpopulations in the peripheral blood and liver were studied in 17 patients with chronic active hepatitis type C (CAH C) by immunoenzymatic and immunofluorescence techniques, using mono-specific T cell antibodies and other reagents. The peripheral blood subsets showed no significant differences between the patients with CAH C and normal controls. In the liver, CD8-positive cells were predominant over CD4- and Leu 7-positive cells. Leu 7-, CD4-, and CD11-positive lymphocytes were all few in number. HLA class I antigen was expressed diffusely on the cell surfaces of the hepatocytes. Serum levels of soluble interleukin 2 receptor (sIL2R) in the CAH C patients were significantly higher than in normal controls (p less than 0.01). In CAH C, sIL2R levels were higher during exacerbations than during remissions (p less than 0.01). These results suggest that cytotoxic T cells (CD8- positive, CD4-negative, and CD11-negative) may play an important role in the pathogenesis of hepatocyte injury in patients with CAH C.

The seroepidemiology of hepatitis A and B in a Japanese town.

Sera collected from 1,118 healthy children and adults aged between four years and 90 years during the period 1989 to 1990, were tested for serological markers of hepatitis A virus (HAV) [antibody to HAV (anti-HAV)] and hepatitis B virus (HBV) [hepatitis B surface antigen (HBsAg) and antibody to hepatitis B surface antigen (anti-HBsAb)]. The overall prevalence rates of anti-HAV, HBsAg, and anti-HBV were 20.2%, 0.36%, and 5.1%, respectively. No body was found to be positive for anti-HAV below 30 years of age but more than 70% of the adults aged 50 years or over were positive for anti-HAV. The level of exposure of HAV infection is declining in Japan and paradoxically at the same time a vast majority of people are becoming susceptible to more severe illness. The fall in prevalence of HBsAg possibly represents the positive impact of ongoing vaccination programs and other preventive measures against HBV.

[Prevalence of TT virus infection and viral integration in human hepatocellular carcinoma].

In 1997, Nishizawa et al cloned a novel DNA virus designated as TT virus (TTV) from a patient with post-transfusion hepatitis and this virus is being thought to be a new hepatitis virus. Approximately 5 to 10% of hepatocellular carcinomas (HCCs) in Japan occurs in hepatitis B virus-negative and hepatitis C virus-negative (NBNC) patients. In order to study the possible role of TTV in hepatocarcinogenesis, we studied the prevalence of the TTV DNA in liver tissue of HCC patients. As a result, TTV was shown not to be specific for NBNC HCC and TTV integration into host DNA was not detected in any HCC patient by Southern blotting.

[Analysis of the allele specific Ag-binding site on murine class II MHC].

Residues 46 and 54 on pigeon cytochrome c 43-58 (p43-58) analogues function as agretopes (sites bound to MHC molecules). Phenylalanine (F) and alanine (A) at positions 46 and 54 on p43-58 respectively bind to I-Ab. Aspartic acid (D) and alanine at positions 46 and 54 respectively bind to I-Ak. To determine the allele specific binding sites (desetope (s)) on class II molecules that are correspondent to the agretopes of peptide antigen (Ag), we analyzed directly binding capacity of p43-58 analogues with glutamic acid (E) at the epitopic position 50 (50E) to L cell transfectants expressing recombinant I-A molecules between b and k types. An Ak binding peptide, 46D50E54A, bound to transfectant possessing amino acid sequence of k type on N-terminal half of alpha-helix of A alpha-chain irrespective of the b type sequence on the other part, whereas an Ab binding peptide, 46F50E54A, did not bind to these transfects. Thus, agretopic residue 46 of 46D50E54A peptides appeared to bind to N-terminal half of alpha-helix of A alpha-chain. To define critical residues for the allele specific peptide binding, we then analyzed peptide binding capacity of Ak mutants substituted one of four polymorphic residues between Ak and Ab molecules. An Ak mutant, Ak alpha(56A), where arginine (R) at position 56 of the Ak alpha-chains was substituted with alanine located at the same position 56 of the Ab alpha-chains hardly bound 46D50E54A. By contrast, the Ak alpha(56A) bound 46F50E54A. Furthermore, Ak restricted T cell hybridomas responded to 46F50E54A but not to 46D50E54A in the presence of the Ak alpha(56A) APC. Thus, an amino acid on the position 56 of A alpha-chain determines critically specificity of the allele specific peptide binding (desetope).

[Determination of dissociation exponent of CO2 used in Henderson-Hasselbalch equation by means of bicarbonate-selective microelectrode].

To measure intracellular ion activity of bicarbonate directly, a double-barreled bicarbonate-selective microelectrode was constructed with a liquid ion exchanger(LIX) containing tri-n-octylammonium, trifluoroacetyl-butyl benzene and octanol. A new dissociation exponent of CO2 (pK') was determined experimentally for a modified Henderson-Hasselbalch equation, in which HCO3 activity was used instead of HCO3 concentration. The temperature effects on pK' and solubility coefficient of CO2 were analyzed over the range of 10 to 40 degrees C. The average values of pK' at room temperature (22 degrees C) were 6.377 and 6.348 in water and frog serum, respectively, and the solubility coefficients of CO2 were 0.048 and 0.046 mM/L/mmHg. The values of pK' plotted on Arrhenius plot were shown linear with 1/T, indicating that the pK' thus obtained can be treated thermodynamically as a first-order kinetics. Under normal circumstances, the values for the intracellular pH predicted from the intracellular bicarbonate activities in the proximal tubule and sartorius muscle of bullfrogs were virtually identical with those obtained directly by the LIX-pH-microelectrodes.

Treatment of asystole and PEA.

Recent reports consistently point to a substantial decline in the incidence of ventricular fibrillation (VF) as the initial rhythm observed by Emergency Medical Service (EMS) responders and a complementary increase in pulseless electrical activity (PEA) and asystole. Historically, efforts at improving survival have focused primarily on patients found in VF. Consequently, the approach for other patients has included frequent pauses in cardiopulmonary resuscitation (CPR) to check for VF followed by shock when VF is observed. However, the "yield" of survivors comes largely from the non-shocked patients. Therefore, it is critical that we start evaluating treatments specifically for the PEA and asystole groups.