Biomedical subjects

S Misawa

Publications and source records attributed to S Misawa.

At least 55 records · Page 3Linked to original sources

PubMed2000

Structure-activity relationship of orally potent tripeptide-based HIV protease inhibitors containing hydroxymethylcarbonyl isostere.

We designed and synthesized a new class of peptidomimetic human immunodeficiency virus protease inhibitors containing a unique unnatural amino acid, allophenylnorstatine [Apns; (2S,3S)-3-amino-2-hydroxy-4-phenylbutyric acid], with a hydroxymethylcarbonyl isostere as the active moiety. From a structure-activity relationship study of HIV-1 protease inhibition, enzyme selectivity for other aspartyl proteases, the antiviral activity and pharmacokinetics in rats, 24c (KNI-227) and 24d (KNI-272, our first clinical candidate) were found to be selective and orally potent HIV protease inhibitors. Moreover, an improvement of the pharmacokinetic features of KNI-272 provided two long-lasting and highly bioavailable compounds (24g: JE-2178, 24h: JE-2179).

Animals↗

PubMed2000

[The procedures for detection of penicillin-resistant Streptococcus pneumoniae and the epidemiology].

Penicillin-resistant Streptococcus pneumoniae was first described in South Africa in 1977 and soon afterward was reported in other countries and in Japan. According to NCCLS standards for antimicrobial susceptibility tests, in vitro activity of S. pneumoniae is the best procedure using the minimum inhibitory concentration method. Benzylpenicillin, cefotaxime or ceftriaxone, and meropenem should be tested by a reliable MIC method and the susceptibility should be reported in the case isolated from blood and/or cerebrospinal fluid. Using the oxacillin test, it is difficult to distinguish penicillin-resistant from intermediate strains or sometimes susceptible strains.

Microbial Sensitivity Tests↗

PubMed2000

[Detection methods for drug-resistant bacteria in routine examination--BLNAR].

The characteristics of resistance, trend of prevalence and current status of beta-lactamase-negative, ampicillin-intermediate or -resistant(BLNAR) strains of Haemophilus influenzae are summarized by our retrospectively analyzed data. The mechanism of this type of ampicillin-resistance is due to altered penicillin-binding proteins(PBPs). Standardized susceptibility tests may differentiate ampicillin-resistant, beta-lactamase-producing strains from beta-lactamase-negative, ampicillin-susceptible strains(BLNAS), but may not differentiate some strains of BLNAR from those of BLNAS. In the cases of serious infections, such as meningitis due to H. influenzae both beta-lactamase activity and ampicillin susceptibility should be confirmed by the MIC procedure.

Ampicillin Resistance↗

PubMed2000

[A proposal of essentials for forensic pathological diagnosis of sudden infant death syndrome (SIDS)].

There are many sudden unexpected infant death cases which are easily diagnosed as sudden infant death syndrome (SIDS) both with or without autopsy in Japan. A SIDS diagnosis may provide a cover for accidental or criminal death. SIDS should not be a convenient diagnostic box that shelters the cases of unexpected infant death which lack the necessary antemortem information to make the correct diagnosis. The authors consider that SIDS should be diagnosed according to the direction of the international definition of SIDS, and propose the following essentials for a forensic pathological diagnosis. 1) A thorough autopsy should be performed based on precise autopsy protocol, including not only histological observation, but also, if necessary, toxicological, bacteriological, viral and/or biochemical examinations. 2) The forensic pathologist should be provided with pertinent information regarding antemortem health status, past clinical history, social circumstances, death scene investigation, etc. In order to collect more precise information, the authors recommend using a questionnaire such as the example in this report to record information from the deceased's guardians. 3) Suspicion of accidental death or infanticide should be completely ruled out. SIDS should be diagnosed only after these three essentials have been satisfied. When there is even a slight suspicion of accidental death or infanticide, or when the forensic pathologist can not obtain pertinent information about the deceased, the causes and classification of the death should be diagnosed as unspecified or undetermined. That is, the causes and classification of the death are undetermined as to whether it is a natural or unnatural death. Furthermore, several warning flags indicating a possible SIDS diagnosis were proposed: a case found dead in a supine position, the existence of a foreign body in the respiratory tract or mild infectious findings. The authors also emphasize the physician's responsibility to report a case found dead or dying of unnatural or clinically unexplained causes to the police. This is the crucial first step in getting an accurate diagnosis of SIDS.

Autopsy↗

PubMed2000

[Survey on postmortem examination to police surgeons and emergency physicians. Possibility of physicians' assist in mass-disaster].

We conducted a questionnaire survey of police surgeons and emergency physicians, inquiring about their experience of medicolegal investigation of death and their willingness to join a death investigation team in a major disaster. The questionnaire also asked about their knowledge about and interest in the forensic specialist system established by the Japanese Society of Legal Medicine. Police surgeons were generally willing to join an investigation team only if a disaster occurred in or close to their hometown, because they could not afford more than several days away from patient care. Although many of the emergency physicians were willing to join a death investigation team, they had difficulty in doing so without permission or orders from their employer or the authorities concerned. The survey found that the percentage of aged police surgeons was increasing among those surveyed. This fact, in combination with the current emphasis of postgraduate education on specialty training, threatens to cause a substantial lack of physicians available for medicolegal investigation of death. Therefore, it is urgently necessary to establish a system of training resident and emergency physicians in medicolegal investigation of death. In addition to providing postgraduate training in medicolegal investigation of death to prospective trainees who are emergency physicians at major hospitals in potential disaster-stricken areas, the medical school should incorporate forensic medicine in postgraduate training programs so that they can actively perform death investigation on disaster victims dying before or after arrival at their hospitals. Furthermore, the forensic community should make every effort to increase the number of autopsies in each department of forensic medicine and to expand the medical examiner system throughout Japan that is currently in practice only in the Metropolis of Tokyo and Yokohama, Nagoya, Osaka and Kobe Cities in order to incorporate forensic training in the postgraduate clinical training programs that will become compulsory in 2004.

Attitude of Health Personnel↗

PubMed1999

Structure-activity relationship of small-sized HIV protease inhibitors containing allophenylnorstatine.

We designed and synthesized a new class of peptidomimetic human immunodeficiency virus (HIV) protease inhibitors containing a unique unnatural amino acid, allophenylnorstatine [Apns; (2S, 3S)-3-amino-2-hydroxy-4-phenylbutyric acid], with a hydroxymethylcarbonyl (HMC) isostere as the active moiety. A systematic evaluation of structure-activity relationships for HIV protease inhibition, anti-HIV activities, and pharmacokinetic profiles has led to the delineation of a set of structural charateristics that appear to afford an orally available HIV protease inhibitor. Optimum structures, exemplified by 21f (JE-2147), incorporated 3-hydroxy-2-methylbenzoyl groups as the P2 ligand, (R)-5,5-dimethyl-1,3-thiazolidine-4-carbonyl (Dmt) residue at the P1' site, and 2-methylbenzylcarboxamide group as the P2' ligand. The present study demonstrated that JE-2147 has potent antiviral activities in vitro and exhibits good oral bioavailability and plasma pharmacokinetic profiles in two species of laboratory animals.

Administration, Oral↗

PubMed1999

Refolding of therapeutic proteins produced in Escherichia coli as inclusion bodies.

Overexpression of cloned or synthetic genes in Escherichia coli often results in the formation of insoluble protein inclusion bodies. Within the last decade, specific methods and strategies have been developed for preparing active recombinant proteins from these inclusion bodies. Usually, the inclusion bodies can be separated easily from other cell components by centrifugation, solubilized by denaturants such as guanidine hydrochloride (Gdn-HCl) or urea, and then renatured through a refolding process such as dilution or dialysis. Recent improvements in renaturation procedures have included the inhibition of aggregation during refolding by application of low molecular weight additives and matrix-bound renaturation. These methods have made it possible to obtain high yields of biologically active proteins by taking into account process parameters such as protein concentration, redox conditions, temperature, pH, and ionic strength.

Amino Acid Sequence↗

PubMed1999

Genotype of glutathione S-transferase and other genetic configurations in myelodysplasia.

We examined polymorphisms of glutathione S-transferase (GST) genes in 159 Japanese patients with myelodysplasia and compared the incidence with that in 43 normal individuals to clarify their pathogenetic significance in myelodysplasia. In individuals with the GSTT1 null genotype, the odds ratios for disease risk were elevated to 2.65 (95%CI; 1.27-5.52) in de novo MDS, 4.62 (1.48-14.4) in therapy-related AML, and 2.94 (1.07-8.07) in AML with triliniage dysplasia. Other representative polymorphisms of GSTs had a similar incidence among patients with myelodysplasia, and those of the controls and other hematological disorders. To further investigate the genetic pathway of myelodysplasia, the association between GST genotype and karyotype or configurations of TP53 and NRAS was evaluated, but no relationship was noted. These results suggest that the GSTT1 null genotype may play a role in an increased risk of myelodysplasia unrelated to other mechanisms of myelodysplasia, such as chromosomal alterations or mutation of TP53 or NRAS.

Acute Disease↗

PubMed1999

Distinct genetic involvement of the TP53 gene in therapy-related leukemia and myelodysplasia with chromosomal losses of Nos 5 and/or 7 and its possible relationship to replication error phenotype.

We examined chromosomes and molecular aberrations in 21 patients with therapy-related leukemias (t-AML) or myelodysplastic syndromes (t-MDS). All patients showed abnormal karyotypes, and chromosomal losses of No. 5 and/or No. 7 (-5/5q- and/or -7/7q-) were identified in 12 patients. Among these 12, six patients (50%) harbored a TP53 mutation, and two of five examined showed microsatellite instability, suggesting replication error (RER+) phenotype. Meanwhile, among the other nine patients without -5/5q- and/or -7/7q-, none harbored a TP53 mutation, and none of five examined showed RER+ phenotype. Thus, TP53 mutations and RER+ phenotype were preferentially associated with specific chromosomal losses in t-AML/MDS. We then screened for mutational events in representative DNA mismatch repair genes; exons 5-7 and 12-15 of the hMSH2 gene and exon 9 of hMLH1. Notably, two unrelated patients showing RER+ phenotype had an identical missense alteration at codon 419 of hMSH2 in their marrow cells and fibroblasts, which were not found in 120 DNA samples from healthy volunteers or patients with other hematological disorders. Consequently, this study revealed a possible relationship of RER+ phenotype accompanying an hMSH2 alteration to the development of therapy-related AML/MDS in association with TP53 mutations and specific chromosomal losses, and suggests that some patients may be predisposed to myelodysplasia after chemotherapy for their primary tumor.

Adult↗

PubMed1999

Micronuclei and nuclear abnormalities observed in erythroblasts in myelodysplastic syndromes and in de novo acute leukemia after treatment.

The frequencies of erythroblasts with micronuclei (EBM) and erythroblasts with aberrant nuclear shapes (EBAN) in bone marrow were evaluated in 60 patients with untreated myelodysplastic syndrome (MDS), and also in 21 patients with acute leukemia before and after treatment, and the results were compared regarding cytogenetic patterns. In patients with acute leukemia, the frequencies of EBM and EBAN in bone marrow were 0.60 +/- 0.35% (mean +/- SD) and 1.2 +/- 1.1% before treatment, respectively, the former of which was higher than those obtained from 93 patients with various nonmalignant diseases (p < 0.01). After treatment with antileukemic drugs, the mean values of them significantly increased 9.7 and 6.1 times from the pretreatment ones, respectively. No correlation was found between the yields of EBM and EBAN and cytogenetic patterns, although regimens including administration of vincristine seemed to cause them more frequently. Most patients with MDS showed a consistent increase of EBM and EBAN at the time of diagnosis irrespective of the treatment; the mean frequencies were 7. 7 and 6.3 times higher than those obtained from patients with nonmalignant diseases, respectively. Furthermore, the numbers of EBM and EBAN were significantly higher in patients with an abnormal karyotype than those with a normal karyotype (p < 0.05 for EBM and p < 0.001 for EBAN). In particular, 8 patients with a monosomy 7q showed a marked increase of EBAN (4.7 +/- 4.4%) and EBAN (13 +/- 6. 5%). These findings revealed that drastic changes in the morphology of erythroblasts were characteristic features of MDS, and may reflect a disturbance in kinetochore/spindle microtubules, such as endoreduplication, c-mitosis or restitution, in addition to chromosome lagging.

Acute Disease↗

PubMed1999

Age- and sex-related changes in toluene metabolism by rat hepatic microsomes in vitro.

Age- and sex-related changes in toluene metabolism by hepatic microsomes of male and female Sprague-Dawley (SD) rats (1 to 20 weeks) were investigated. A major metabolite of toluene, benzyl alcohol (BA), was measured by high-performance liquid chromatography (HPLC). At low substrate toluene concentrations (0.4 mM), in male rats, BA increased dramatically with development, reaching a peak at 5 weeks of age, rapidly decreasing thereafter. In female rats, BA increased dramatically with development at 3 to 5 weeks of age, and then declined gradually to a low level. Gender differences were obtained at 5 and 20 weeks of age, with BA products being higher in males than in females. At high substrate toluene concentrations (5.0 mM), in male rats, the BA formation pattern was similar to that at the low substrate concentration, although the rate of increase with age was slower. In female rats, a peak was obtained at 3 weeks of age, and then declined gradually to a low level. Gender differences were obtained at 5, 15 and 20 weeks of age, with BA products being higher in males than in females. These results indicate that toluene metabolism exhibits age and gender differences.

Aging↗

PubMed1999

[Rapid diagnosis of infectious diseases; features and limitations of the microscopic examination of clinical specimens].

The diagnosis of infectious diseases relies on the microbiological examinations. The microscopic examination of clinical specimens has been well known as one of the rapid methods in diagnostic microbiology. The reasons for the microscopic examination in the clinical microbiology are emphasized and summarized as the following features and limitations: ADVANTAGES OF MICROSCOPY. The use of a stained smear microscopy by Gram, Ziehl-Neelsen and fluorochrome stains still remains the most available, easy to perform, and inexpensive. This technique can be done routinely in a variety of clinical settings. The direct microscopy provides judging specimen quality, detecting a variety of organisms in clinical specimens, and evaluating the type of inflammatory response. Typical Gram reactions, morphologies and arrangements of the observed organisms may give the presumptive identification of some certain etiological bacteria, yeasts or fungi, and significant of the organisms. The observing organisms and those forms may also guide to the laboratory in selecting appropriate isolation media and culture methods, and aid to the physician in selecting an empirical antibiotic therapy. DISADVANTAGES AND LIMITATIONS OF MICROSCOPY. The microscopy of clinical specimen is much less sensitive than the culture method for detection of small numbers of bacteria. A specimen usually contains 10(4) to 10(5) or more organisms per milliliter before it is likely that organisms will be seen on a smear. The appearance of bacteria on Gram-stained smears does not permit the identification of species. FACTORS AFFECTING TO RESULT OF MICROSCOPIC EXAMINATION. A number of factors may affect the result of the microscopic examinations. Specimen quality, clinical presentations of the patients, presence of the various cellular components in the background of smear, bacteriological statistics, and individuals in the microbiology laboratory are responsible to the reliability and quality of the results. The concordance between results obtained from a microscopy and from further tests may also provide sufficient information to presumptive identification and diagnosis. Laboratory observers, whom should have abundant experiences and receive sufficient training, are requiring for control and quality of the examination.

Bacteria↗

PubMed1998

Significance of chromosomal alterations and mutations of the N-RAS and TP53 genes in relation to leukemogenesis of acute myeloid leukemia.

We examined chromosomes and mutations of the N-RAS and TP53 genes in 73 patients with acute myeloid leukemia (AML). Twenty-six patients showed a reciprocal chromosomal translocation or an inversion, and 34 patients showed only unbalanced aberrations. Balanced aberrations were predominantly detected in the AML patients who did not have myelodysplasia, preceding myelodysplastic syndrome, and a history of chemotherapy or radiation therapy. In contrast, unbalanced aberrations were more frequently seen in the patients with AML with trilineage myelodysplasia, AML transformed from MDS, and therapy-related AML. Twenty-two mutations of the N-RAS and TP53 genes were detected, and these mutations were frequently associated with unbalanced chromosomal aberrations. Furthermore, the spectrum of mutations was suggestive of an exposure to alkylating chemicals.

Acute Disease↗

PubMed1998

Pharmacokinetic interactions between acute alcohol ingestion and single doses of benzodiazepines, and tricyclic and tetracyclic antidepressants -- an update.

Recent reports of interactions between alcohol and benzodiazepines, tricyclic and tetracyclic antidepressants during their acute concomitant use are reviewed. Acute ingestion of alcohol (ethanol) with tranquilizers or hypnotics is responsible for several pharmacokinetic interactions that can have significant clinical implications. In general, metabolism of these drugs is delayed when combined with alcohol but some reports have suggested otherwise. The amount of alcohol consumed, the presence or absence of liver disease, and differences in the dosage and administration of these drugs may account for the observed discrepancies. In recent years, the cytochrome P450 (P450 or CYP) isoenzyme that catalyses the metabolism of these drugs has also been identified. However, since changes in the pharmacogenetic metabolism of benzodiazepines and tricyclic and tetracyclic antidepressants are mainly governed by CYP2C19 and CYP2D6, caution is needed when used together with alcohol.

Antidepressive Agents↗

PubMed1998

Changes in the enzymatic activities of beagle liver during maturation as assessed both in vitro and in vivo.

1. We have examined changes in caffeine and trimethadione (TMO) metabolism in vivo, agents which are used as probe drugs. In this study the total body clearance (Cl) of caffeine and TMO was low 1 week after birth (week 1), increased rapidly from week 3, peaked and then decreased gradually until reaching the level for the mature, adult dog. The elimination half-life (t1/2) of caffeine and TMO was prolonged during week 1; however, it then gradually became shorter. Gradually it became longer and reached the level for the adult dog. The apparent volume of distribution (Vd) of caffeine did not change throughout the study. However, the Vd of TMO was only high during week 1. 2. The in vitro changes in a variety of typical substrates for seven different cytochrome P450 (CYP) isozymes were examined. In this study three different patterns of metabolism can be identified: (1) activity is low immediately after birth, increases, peaks and then decreases to the adult dog level (p-nitroanisole; CYP1A1, caffeine; CYP1A2, benzphetamine; CYP3A/2B(?), aniline; 2E1 and TMO; CYP2C9/2E1/3A4); (2) activity generally increases rapidly soon after birth, continues to increase, peaks and then gradually decreases to the adult level (phenytoin; CYP2C9); and (3) activity is high (about the same level as the adult) immediately after birth, decreases and then gradually increases to the adult level (erythromycin; CYP3A4/5). 3. The results of these in vivo and in vitro studies suggest that changes in enzyme activity are due to differences in P450 isoenzymes during development.

Alanine Transaminase↗

PubMed1998

Rare alteration of genomic structure or expression of the DPC4 gene in myelogenous leukemias.

We examined homozygous deletion, point mutation and expression of DPC4 gene, a recently isolated candidate pancreatic tumor suppressor gene, in 53 patients with myelogenous leukemias and 5 cell lines. The patients consisted of 34 cases of chronic myelogenous leukemia including 22 in the chronic phase, 3 in the accelerated phase, and 9 in blastic crisis, and 19 with acute myelogenous leukemia including 9 at the initial presentation and 10 at relapse. Polymerase chain reaction (PCR)-based deletion analysis for DPC4 exon 8 and PCR-single strand conformation polymorphism study for the entire coding region were carried out. Homozygous deletion or subtle mutation was not detected in any of the samples examined. However, 3 patients with various clinical phases showed a decrease of DPC4 expression. These results suggest that DPC4 alteration is not a crucial event in the development or the progression of myelogenous leukemias.

DNA-Binding Proteins↗

PubMed1998

Acute liver damage with characteristic apoptotic hepatocytes by ingestion of Aplysia kurodai, a sea hare.

A case of acute liver damage by ingestion of Aplysia kurodai, a sea hare is reported. A 40-year-old man, complaining of vomiting and pyrexia after eating a sea hare, was admitted. Laboratory data showed mild liver damage with sustained elevations of aminotransferases. Microscopic findings in the liver biopsy specimen revealed characteristic apoptotic hepatocytes accompanied by mitotic hepatocytes. It is suggested that bioactive substances in the sea hare might induce such apoptosis of hepatocytes in the liver.

Adult↗

PubMed1998

cis-Diamminedichloroplatinum induces peroxisomes as well as CYP4A1 in rat kidney.

Effects of cis-diamminedichloroplatinum (cisplatin) on rat kidney were investigated. Clinical parameters in rat urine and blood were studied. Blood urea nitrogen (BUN) and creatinine in blood and K+ in urine increased, but Na+ in urine decreased. Contents of total P450 and metabolic activities towards lauric acid and arachidonic acid in rat renal microsomes were not changed by cisplatin treatment. The levels of P450 isozymes (CYP4A1, 4A2, 4A8 and 2C23) were determined in rat renal microsomes by immunoblotting. The levels of CYP4A2 and 4A8 which are lauric acid omega-hydroxylases were not changed, but the levels of CYP2C23 and 4A1 were increased significantly by cisplatin treatment. Effects of clofibrate, a typical inducer for CYP4A1, on rat kidney were compared with those of cisplatin. Clofibrate induced palmitoyl CoA oxidase (a marker enzyme of peroxysome), CYP4A1, and CYP4A2 and reduced triglyceride level in plasma. Cisplatin had similar effects to clofibrate and induced peroxysomes as well as CYP4A1, although the effects were at a lesser extent than those of clofibrate. The induction levels of CYP4A1 correlated with increased levels of BUN. The present findings suggest that induction of P450 by cisplatin may take part in the renal injury or nephrotoxicity of cisplatin.

Animals↗