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Biomedical subjects

H Shiraki

Publications and source records attributed to H Shiraki.

At least 55 records · Page 3Linked to original sources
PubMed1992

Estimation of right ventricular volume by modified echocardiographic subtraction method.

To evaluate the accuracy and clinical utility of right ventricular volume estimated by a modified echocardiographic subtraction method versus Krebs' original subtraction method, an experiment was performed on hearts excised from 25 animals (dogs, pigs, and cows) followed by a clinical study of 41 patients with heart disease. Right ventricular volume was measured by subtracting the left ventricular volume from that of the whole heart based on echocardiographic apical two- and four-chamber views by means of the area-length method. In the animal heart study, the coefficient of variation between the right ventricular volume estimated by the modified method and the true volume was +/- 13%. The regression equation was y = 0.94x + 4.15 (r = 0.987, p less than 0.001) and showed good correlation, whereas the right ventricular volume obtained by the original method underestimated the true volume (coefficient of variation = +/- 25%, y = 0.59x + 1.11; r = 0.976, p less than 0.001). In the clinical study, the coefficient of variation between right ventricular volume estimated by the modified echocardiographic method and RV volume estimated by radionuclide ventriculography was +/- 15%. The regression equation was y = 0.80x + 13.3 (r = 0.935, p less than 0.001). This correlation was better than that obtained by the original method (coefficient of variation = +/- 16%), where the regression equation was y = 0.60x + 2.43 (r = 0.888, p less than 0.001). Thus the accuracy of the modified subtraction method was validated, and this method showed a better correlation than the original method both experimentally and clinically.

Adolescent↗
PubMed1992

Effect of phosphoenolpyruvate on metabolic and morphological recovery of red cells after prolonged liquid storage and subsequent freezing in glycerol medium.

The present study was designed to determine the effects of (i) phosphoenolpyruvate (PEP) treatment of red blood cells (RBCs) previously cold stored for a prolonged period in a liquid medium and (ii) the freezing of these treated cells in glycerol. RBCs stored for 21 days at 4 degrees C were incubated for 30 min at 37 degrees C with rejuvenant solution containing 50 mM PEP, 60 mM mannitol, 30 mM sodium chloride, 25 mM glucose, and 1 mM adenine, pH 6.0, and then frozen at -80 degrees C for 4 weeks. Red cell recovery as frozen and thawed red cells (FTRCs) after deglycerolization was increased to 80 +/- 4% compared to 43 +/- 9% in units without rejuvenation; the percentage of PEP-treated FTRCs was similar to the percentage of FTRCs recovered from fresh RBCs within 5 days after donation. Incubation of RBCs with PEP solution restored ATP and 2,3-DPG to levels seen in fresh RBCs, and also facilitated transformation of crenated RBCs to discocytes. These results indicate that maximum recovery of viable RBCs can be attained when FTRCs are processed from cells stored in the frozen state after they had been rejuvenated with PEP even after prolonged liquid storage.

2,3-Diphosphoglycerate↗
PubMed1992

Linear antigenic regions of the structural proteins of human T-cell lymphotropic virus type I detected by enzyme-linked immunosorbent assays using synthetic peptides as antigens.

We synthesized 46 sequential peptides 21 to 39 amino acids long over the structural protein of human T-cell leukemia virus type I (HTLV-I; the p19 and p24 gag protein and the gp46 and p20E env proteins) and tested their reactivities against antibodies in sera from HTLV-I healthy carriers and patients diagnosed as having human T-cell leukemia-lymphoma (ATLL) and myelopathy (HAM) by using an enzyme-linked immunosorbent assay. Of the 46 synthetic peptides, 18 peptides (2 corresponding to the p19 gag protein, 2 corresponding to the p24 gag protein, 8 corresponding to the gp46 env protein, and 6 corresponding to the p20E env protein) reacted with antibodies in the sera from HTLV-I healthy carriers. In particular, the peptides comprising amino acids 100 to 119 and 119 to 130 of the gag and 175 to 199, 213 to 236, 253 to 282, and 288 to 317 of the env proteins reacted with antibodies in sera from more than 30% of HTLV-I healthy carriers. These peptides also showed high reactivities to the antibodies in the sera from patients with ATLL and HAM. The results indicate that the predominant antigenic regions of the structural protein of HTLV-I were located at the C-terminal end of the p19 gag protein and the C-terminal half of the gp46 env protein, and the corresponding peptides proved to be useful antigens in detecting antibodies in the sera from individuals infected with HTLV-I.

Amino Acid Sequence↗
PubMed1992

A simple and reliable method for the detection and quantitation of the human T-cell leukemia virus type-I provirus in peripheral blood mononuclear cells of seropositive blood donors.

Human T-cell leukemia virus type I (HTLV-I) antibody detection has been widely used to screen HTLV-I carriers. Sometimes, however, it gives false positive or negative results. A demonstration of the HTLV-I provirus from patients' peripheral blood mononuclear cells (PBMC) should, therefore, give the crucial evidence for them being HTLV-I carriers. We established a simple and reliable method using the polymerase chain reaction (PCR) to detect one molecule of HTLV-I provirus in 100 x 10(3) PBMC, during which internal control primers for the human beta-globin gene were also employed in the same reaction tube to check the success of the amplification reaction. We can thus easily avoid any false negative judgement and quantitate the HTLV-I provirus in PBMC simply by diluting the sample before PCR. One ml blood was enough for ten or more determinations by PCR. Analysis of seropositive blood from donors demonstrated a wide range for the number of HTLV-I provirus in PBMC. The method could conveniently be used for quantitating HTLV-I proviruses and following up HTLV-I carriers to study the pathophysiology and mode of HTLV-I transmission.

Base Sequence↗
PubMed1992

Enzyme immunoassay with synthetic peptides to detect anti-HTLV-I antibodies.

We developed an enzyme immunoassay (EIA) system to detect antibodies to human T-lymphotropic virus type I (HTLV-I). This system uses chemically synthesized oligopeptides to capture anti-HTLV-I antibodies in serum. The two epitopes of HTLV-I proteins exhibiting the most specific antigen-antibody reaction reside within amino acids 100-130 of p19, a core protein encoded by gag, and amino acids 175-199 of gp46, an envelope glycoprotein encoded by env. This new assay uses synthetic peptides corresponding to these two regions modified by adding two lysine residues at the amino terminal of each peptide to facilitate the binding to the surface of the microtiter plate wells. We compared the performance of our EIA with gelatin-particle-agglutination (PA) and indirect-immunofluorescence (IF) assays, both of which use viral proteins purified from virus-carrying cell cultures. Mass screening by EIA with various synthetic peptides was more accurate than the current confirmatory IF assay.

Agglutination Tests↗
PubMed1991

Serological discrimination between HTLV-I and HTLV-II antibodies by ELISA using synthetic peptides as antigens.

Using the peptides from amino acids 100-130 of the HTLV-I gag protein, 175-199 of the HTLV-I env protein and the corresponding peptides of HTLV-II (amino acids 106 to 135 of the gag protein and 171 to 196 of the env protein), we tested for reactivity against antibodies by enzyme immunoassay in sera from HTLV-I and HTLV-II carriers. The peptides derived from the env proteins have high specificity for antibody binding. The peptide based on amino acids 175-199 of HTLV-I reacted with antibodies in sera from all HTLV-I carriers, and the peptide composed of amino acids 171-196 of HTLV-II reacted with antibodies in sera from all HTLV-II carriers. For the peptides derived from the gag proteins, we observed some cross-reactivity in sera from persons with anti-HTLV-I and anti-HTLV-II, due to antibody binding to the peptide corresponding to 12 amino acids from the C-terminal end of the gag protein. Separate enzyme immunoassays that used the four synthetic peptides as antigens clearly distinguished between serum with antibodies to HTLV-I or HTLV-II in various individuals and excluded false positive results using the particle agglutination assay that used a whole-virus lysate of HTLV-I as antigen.

Amino Acid Sequence↗
PubMed1991

Identification of a neutralization epitope on the envelope gp46 antigen of human T cell leukemia virus type I and induction of neutralizing antibody by peptide immunization.

We have generated a number of mAb against various epitopes on the external envelope glycoprotein, gp46, of human T cell leukemia virus type I (HTLV-I) from a WKA rat immunized with a recombinant vaccinia virus containing the HTLV-I env gene. Among these mAb, one group of mAb, represented by a mAb designated LAT-27, could neutralize the infectivity of HTLV-I, as determined by a HTLV-I-mediated cell fusion inhibition assay. LAT-27 also interfered with transformation of normal T lymphocytes by HTLV-I in vitro. An antibody-binding assay using overlapping synthetic oligopeptides showed that LAT-27 bound specifically to 10-mer peptides that contained the gp46 amino acid sequence 191-196 (Leu-Pro-His-Ser-Asn-Leu). Antibodies from HTLV-I+ humans interfered with the binding of LAT-27 to gp46 Ag. Sera from rabbits immunized with a LAT-27-reactive peptide, 190-199, conjugated with OVA, but not sera from OVA-immunized rabbits, reacted with gp46 Ag and neutralized infectivity of HTLV-I. These results show that the HTLV-I neutralization epitope recognized by LAT-27 locates to the gp46 amino acids 191-196, and that immunization with a peptide containing the LAT-27 epitope can elicit an HTLV-I neutralizing antibody response.

Animals↗
PubMed1991

Elevated antibodies to synthetic peptides of HTLV-1 envelope transmembrane glycoproteins in patients with HAM/TSP.

We studied the antibody response to various kinds of well-characterized synthetic peptides of human T lymphotropic virus type 1 (HTLV-1) envelope glycoproteins in patients with HTLV-1 associated myelopathy (HAM)/tropical spastic paraparesis (TSP) and non-HAM/TSP HTLV-1 carriers. The serum antibody titers to most of the synthetic peptides were significantly higher in patients with HAM/TSP than those in non-HAM/TSP HTLV-1 carriers. However, the degree of the increase of antibody titers to the synthetic peptides corresponding to the transmembrane portions of HTLV-1 envelope glycoproteins (env-p20E), such as p20E 332-352, 374-392, 426-448 and 458-488, was greater than those to synthetic peptides of exterior portions of HTLV-1 envelope glycoproteins (env-gp46) in sera from patients with HAM/TSP. Antibodies to env-p20E 332-352 and 374-392 were elevated in the cerebrospinal fluid (CSF) only from patients with HAM/TSP but not from non-HAM/TSP HTLV-1 carriers. These data indicate that the increase of antibody titers to transmembrane portions of HTLV-1 envelope glycoproteins in sera and CSF is a characteristic feature of antibody response in patients with HAM/TSP and may be closely associated with the development of HAM/TSP from non-HAM/TSP HTLV-1 carriers.

Adult↗
PubMed1991

Identification and mapping of neutralizing epitopes of human parvovirus B19 by using human antibodies.

We identified and mapped the regions responsible for neutralization in the human parvovirus B19 structural protein by using region-specific human antibodies derived from seropositive blood donors. The region-specific antibodies were purified by using affinity columns coupled with synthetic peptides of the hydrophilic regions including the beta-turn structure deduced by the predicted secondary structure of VP2. Fifteen highly specific antibodies against the synthetic peptides were obtained. Ten of them were able to precipitate the radiolabeled virus. Six of them proved to be able to protect the colony-forming unit erythroid cells in human bone marrow cell cultures from injury by the virus. The sequences recognized by the six neutralizing antibodies were sites corresponding to amino acids 253 to 272, 309 to 330, 325 to 346, 359 to 382, 449 to 468, and 491 to 515 from the amino-terminal portion of VP2. These observations suggest that the neutralizing epitopes were distributed in the region from amino acid 253 in the amino-terminal portion of VP2 to the carboxyl terminus of VP2.

Amino Acid Sequence↗
PubMed1991

Identification of the region including the epitope for a monoclonal antibody which can neutralize human parvovirus B19.

In this study, we identified a region in the human parvovirus structural protein which involves the neutralization of the virus by a monoclonal antibody and site-specific synthetic peptides. A newly established monoclonal antibody reacted with both viral capsid proteins VP1 and VP2. The epitope was found in six strains of independently isolated human parvovirus B19. The monoclonal antibody could protect colony-forming unit erythroid in human bone marrow cell culture from injury by the virus. The monoclonal antibody reacted with only 1 of 12 peptides that were synthesized according to a predicted amino acid sequence based on nucleotide sequences of the coding region for the structural protein of B19 virus. The sequence recognized by the antibody was a site corresponding to amino acids 328 to 344 from the amino-terminal portion of VP2. This evidence suggests that the epitope of the viral capsid protein is located on the surface of the virus and may be recognized by virus-neutralizing antibodies.

Amino Acid Sequence↗
PubMed1990

Generation and characterization of monoclonal antibodies against multiple epitopes on the C-terminal half of envelope gp46 of human T-cell leukemia virus type-I (HTLV-I).

In order to study the antigenicity of envelope 46 kDa glycoprotein (gp46) of human T-cell leukemia virus type-I (HTLV-1), we have generated monoclonal anti-gp46 antibodies (MAbs), REY-7, REY-11, REY-16, REY-30, MET-2 and MET-3 from rats and mice. Immunoblot and immunofluorescence assays showed that these MAbs recognize gp46 and its related antigens, and specifically stained HTLV-I-bearing cells. All MAbs reacted with a recombinant gp46 antigen, N147, expressing the 147 amino acids in the C-terminal half of gp46. By using various synthetic peptides corresponding to the gp46 sequence, epitopes recognized by REY-7 and MET-3, REY-11 and REY-16, and REY-30 were mapped to regions corresponding to the amino acids 175-199, 253-282 and 288-312, respectively. MET-2 did not react with any of the peptides used. These results indicate that the present MABs are directed against at least 4 distinct epitopes expressed on the C-terminal half of gp46. The binding of these MAbs to gp46 was specifically inhibited by sera from HTLV-I-infected individuals, but none of these MAbs inhibited the cell fusion activity of HTLV-I.

Animals↗
PubMed1990

Detection of antibodies to human T-lymphotropic virus type I by using synthetic peptides.

We describe an enzyme-linked immunosorbent assay (ELISA) for antibodies to HTLV-I using synthetic peptides corresponding to antigenic regions of HTLV-I structural protein. We observed that the peptides amino acid 100-119, 100-130, 131-160 and 295-314 of the gag protein, and 89-115, 175-199, 350-386 and 458-488 on the env protein correspond to the antigenic regions of HTLV-I structural protein. In particular, the peptide corresponding to amino acid 100-130 of the gag protein reacted with antibodies in all sera from HTLV-I carriers diagnosed by particle agglutination assay (PA) and indirect immunofluorescence assay (IF), but did not react with sera from healthy volunteers judged to be negative by PA and IF. Our results indicate that the ELISA using the peptide 100-130 of the gag protein can be used for donor screening of HTLV-I antibodies.

Amino Acid Sequence↗
PubMed1990

Application of phosphoenolpyruvate into the preparation of frozen and thawed red cells.

Current standards recommend that red cells (RBCs) should be frozen within 5 days of donation. However, the guideline regarding freezing of RBCs may be cause difficulties in cases that autologous or rare units intended for transfusion may not be used as scheduled. Therefore, we examined how to freeze the RBCs after prolonged liquid storage. Standard units were stored at 4 degrees C for 21 days, incubated with rejuvenant solution containing 50 mM phosphoenolpyruvate (PEP), and then frozen at -80 degrees C for 4 weeks. RBCs recovery after deglycerolization procedure was 80 +/- 4% of the original value, which was similar to the level seen in fresh RBCs and twice that in nontreated units. The incubation of old RBCs with PEP not only increased ATP and 2,3-DPG levels, but also facilitated the transformation of crenated erythrocytes to discocytes. These results indicated that RBCs after maximum liquid storage could be frozen by rejuvenation with PEP solution, which would be expected to give adequate recovery of viable RBCs after processing for FTRC.

2,3-Diphosphoglycerate↗
PubMed1989

Diagnosis of myocardial ischemia by the pressure-rate quotient and diastolic time interval during coronary artery bypass surgery.

Diagnosis of intraoperative myocardial ischemia by the rate-pressure product (RPP), pressure-rate quotient (PRQ), and diastolic time interval (DTI) was studied in 13 patients undergoing coronary artery bypass grafting (CABG) with fentanyl, vecuronium/pancuronium, and enflurane anesthesia. Criteria for ischemia were 1 mm of ST segment elevation or depression or T wave inversion on the ECG. RPP was calculated by multiplying the systolic arterial pressure (SAP) times the heart rate (HR); PRQ was determined by dividing the mean arterial pressure (MAP) by the HR; and DTI was defined as the interval from the closure of the aortic valve on M-mode transesophageal echocardiography to the onset of the QRS complex on the ECG. Six of 13 patients experienced episodes of ischemia (a total of 32 episodes out of 134 measurements). RPP of 12,000 was not found to correlate with myocardial ischemia (P greater than 0.05), whereas PRQ of less than 1.0 or DTI of less than 400 ms was associated with myocardial ischemia (P less than 0.005). In this preliminary study, it is concluded that both the PRQ and DTI are indicators of myocardial ischemia; it is also suggested that ischemia may be prevented by maintaining (1) DTI over 400 ms (HR less than 75 beats per minute), and (2) PRQ greater than 1.0 (MAP greater than HR).

Anesthesia, General↗