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Biomedical subjects

M Maki

Publications and source records attributed to M Maki.

At least 181 records · Page 10Linked to original sources
PubMed1989

Isolation and identification of embryo-derived platelet-activating factor in mice.

We isolated a platelet-activating factor (PAF) derived from mouse embryos and identified it by bioassay utilizing washed rabbit platelets. We also tried further characterization of the factor by high-performance liquid chromatography (HPLC) and electron-impact mass spectrometry (EI-MS). 1. In the thin-layer chromatography (TLC) of the medium after a two day culture of 30 embryos at the two-cell stage, no obvious spot appeared at the site of 1-O-acetyl-2-O-alkyl-SN-glyceryl-3-phosphocholine (AGEPC). But a small, pale spot appeared at the site of lyso-AGEPC. 2. A remarkable aggregation activity was present at the site of the Rf and appearance time that was almost the same as for AGEPC in both TLC and HPLC. However, detection of the substance by UV absorption (203nm) in HPLC was unsuccessful. 3. The PAF activity shown in the culture medium was suspected to be 10(-10 - 10(-11) M/embryo and it was not inhibited by pretreatment with indomethacin and ADP scavenger. 4. Embryo-derived PAF had an HPLC appearance time 1-2 min. longer than that of synthetic AGEPC (C16). EI mass spectrum of embryo-derived PAF was partly inconsistent with that of synthetic AGEPC (C16). These results confirm the evidence of PAF release from mouse embryos and show the possibility that a far greater amount of its lyso-derivative is present in the culture medium. Embryo-derived PAF is presumed to be AGEPC or a substance resembling AGEPC in its chemical structure and some structural difference may exist between embryo-derived PAF and synthetic AGEPC (C16).

Animals↗
PubMed1988

Sequence requirements for nucleolar localization of human T cell leukemia virus type I pX protein, which regulates viral RNA processing.

The posttranscriptional regulator (p27x-III) of human T cell leukemia virus type I (HTLV-I) is located predominantly in the cell nucleolus. A highly basic amino-terminal sequence (NH2-Met-Pro-Lys-Thr-Arg-Arg-Arg-Pro-Arg-Arg-Ser-Gln-Arg-Lys-Arg-Pro-Pro -Thr- Pro) in this protein, when fused to the amino termini of beta-galactosidase and p40x of HTLV-I, acts as an autonomous signal capable of directing the hybrid proteins to the cell nucleolus.

Amino Acid Sequence↗
PubMed1988

Analysis of structure-function relationship of pig calpastatin by expression of mutated cDNAs in Escherichia coli.

Structure-function relationships in pig calpastatin were investigated. Calpastatin is an endogenous inhibitor protein specifically acting on calpains (Ca2+-dependent cysteine endopeptidases). We recently cloned and sequenced the cDNA for pig heart calpastatin and determined the amino acid sequence of the molecule from the nucleotide sequence. Various deletion mutants in one of the four internally repetitive domains (Domain 3, approximately 140 amino acid residues) were created by in vitro site-directed mutagenesis of a cloned cDNA fragment and expressed in Escherichia coli. Deletion of a conserved region on either the amino-terminal or carboxyl-terminal side caused a drastic loss of inhibitory activity against calpain I (low Ca2+-requiring form) and, to a lesser degree, against calpain II (high Ca2+-requiring form). Inhibitory activities were below the detectable level in mutants deleted further toward the central region. Substitution of two amino acids in the latter region of the wild-type Domain 3 protein caused a drastic loss of activity against both calpains. The creation of lowered affinity inhibitors enabled us to perform a conventional kinetic analysis which showed the mode of inhibition to be competitive. Prediction of the secondary structure of Domain 3 suggests that both the amino- and carboxyl-terminal conserved regions form alpha-helical structures, which are largely located in the interior of the calpastatin molecule, whereas the central region does not form alpha-helix or beta-structure. The central region contains a 12-residue consensus sequence common to Domains 1, 2, and 4, and this portion is predicted to be located on the surface of the calpastatin molecule. These results suggest that the central conserved region of each domain of calpastatin is an area for direct interaction either with the active center of calpain or a region in close proximity, and the rest of the domain is a region stabilizing the functionally important tertiary structure of the domain.

Amino Acid Sequence↗
PubMed1988

Pig heart calpastatin: identification of repetitive domain structures and anomalous behavior in polyacrylamide gel electrophoresis.

Isolation and nucleotide sequencing of the complementary DNA for pig heart calpastatin have been completed. The amino acid sequence of 713 residues predicted from the nucleotide sequence contains five domains, each composed of approximately 140 amino acid residues. A unique N-terminal domain is followed by four mutually homologous domains. The best fit alignment of these four domains gives residue identities between any two domains of 22.5-36.0%. The analysis of the sequence similarities by several methods also suggests the existence of additional shorter repeats at intervals of 60-80 residues. The calculated molecular weight of pig calpastatin of 713 amino acid residues (Mr 77,122) is significantly lower than the value of purified pig heart calpastatin (Mr 107,000) estimated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE). The expression of the calpastatin genes in Escherichia coli and the detection of the translation products of 713, 366, and 140 amino acid residues by the specific anti-calpastatin antibody indicate that the products always migrate considerably slow on SDS-PAGE, giving an average of 1.53 for the ratio of the molecular weight estimated by SDS-PAGE to the value calculated from the amino acid sequences. It is most likely that the discrepancy in the molecular weight is caused by an anomalous behavior of calpastatin in SDS-PAGE.

Amino Acid Sequence↗
PubMed1988

Analysis of the use of HIV antibody testing in a Minnesota hospital.

We retrospectively studied the clinical use of human immunodeficiency virus (HIV) antibody serology at one 450-bed medical center and affiliated clinics from April 1985 through August 1986. No restrictions were placed on the use of HIV antibody serology during that time, although it was recommended that consent be obtained and risk-reduction information be provided. Testing was performed for 275 patients; results for 25 (9%) of these were positive. Nearly half (44%) of the patients had no recognized risk factor for HIV infection recorded in their charts. For an additional 44% of the patients, the test was medically indicated but consent and counseling were not documented. For only 10% of HIV antibody tests was there notation that consent was obtained and that risk-reduction information was provided. These results indicate that HIV antibody testing is often done without consent and that opportunities to provide risk-reduction counseling are being missed.

Enzyme-Linked Immunosorbent Assay↗
PubMed1988

The second nation-wide survey in Japan of vitamin K deficiency in infancy.

Throughout Japan a total of 543 cases of vitamin K deficiency occurring in infants over 2 weeks of age were reported from January 1981 to June 1985. Of these cases, 427 showed no obvious reasons for vitamin K deficiency; this sort of case is known as "idiopathic vitamin K deficiency in infancy". Another 57 cases had bleeding episodes due to vitamin K deficiency associated with obvious hepatobiliary lesions, chronic diarrhoea, long-term antibiotic therapy, etc; this sort is called "secondary vitamin K deficiency in infancy". The third group, consisting of 59 cases, was made up of the so-called "near miss" type, in which a haemorrhagic tendency, without any obvious clinical haemorrhage, was discovered by Normotest, at the time of mass screening in most cases. In the idiopathic group, 269 cases (63.0%) developed bleeding episodes between the 1st and 2nd months of age, and 387 cases (90.0%) were entirely breast-fed. Intracranial haemorrhage was observed in 353 cases (82.7%) of this group. Moreover, slight elevation of serum transaminase and direct type bilirubin levels were observed in the idiopathic group. Liver dysfunction of unknown origin may play some role in the onset of vitamin K deficiency in infancy.

Alanine Transaminase↗
PubMed1988

Diminished sympathetic excitation of locus coeruleus noradrenergic neurons in the conscious mature spontaneously hypertensive rat.

We undertook a study to determine whether the activation of the nucleus locus coeruleus might be responsible for the sympathetic hyperactivity in the spontaneously hypertensive rat (SHR). Conscious mature SHR showed increased arterial pressure and plasma catecholamines with electrical stimulation of the locus coeruleus. However, SHR showed smaller increases in arterial pressure and plasma noradrenaline than Wistar-Kyoto rats (WKY). The spontaneous unit discharge in locus coeruleus neurons responded reciprocally to peripherally induced changes in arterial pressure and blood volume. However, the unit discharge in the SHR locus coeruleus is less responsive than that in WKY. Therefore, the locus coeruleus in mature SHR does not seem to be involved in the hyperactivity of the sympathetic nervous system. However, this may not be the case in young SHR.

Animals↗
PubMed1988

Coagulation-fibrinolytic and kinin-forming systems in toxemia of pregnancy.

The relationship between the hemostatic system and the severity of toxemia was studied in 78 pregnant women with toxemia. The activities of plasma antithrombin III (AT-III), prekallikrein, plasminogen, alpha 2-plasmin inhibitor and factor XIII were determined using the chromogenic substrate and fluorescent methods. The antigens of both AT-III and factor XIII were determined by the single radial immunodiffusion method. Plasma bradykinin was determined by radioimmunoassay. The main results obtained were as follows. Both activities of AT-III and plasma prekallikrein decreased as the gestosis index increased (p less than 0.001), and a significant negative correlation was observed between the total score of the gestosis index and AT-III (r = -0.447, p less than 0.005) or plasma prekallikrein (r = -0.434, p less than 0.005). The levels of plasminogen, alpha 2-plasmin inhibitor and factor XIII decreased and plasma bradykinin increased in toxemia. Among the various factors, plasma AT-III and prekallikrein were the most sensitive indicators of the severity of toxemia.

Antigens↗
PubMed1988

Phospholipase C activity and phosphatidylinositol in amniotic fluid. A possible contribution of the fetus to the initiation of human parturition.

We investigated the mutual role between amniotic fluid and fetus in the mechanism of initiating human parturition. Phosphatidylinositol in amniotic fluid began to increase from around 30 weeks to 36 or 37 weeks of gestation and then gradually decreased toward term. On the other hand, we demonstrated phospholipase C activity in amniotic fluid, which increased toward term, and we also demonstrated the high phospholipase C activity in neonatal urine, which was 58-fold higher than that in amniotic fluid. The molecular weight of phospholipase C from neonatal urine was estimated to be 33,000 daltons. It was concluded that the fetus relates to onset of labor by producing arachidonic acid in amniotic fluid by the reaction between phosphatidylinositol from fetal lung and phospholipase C from fetal urine.

Amniocentesis↗
PubMed1987

All four internally repetitive domains of pig calpastatin possess inhibitory activities against calpains I and II.

Complementary DNA portions coding for each domain (domain L and internally repetitive domains, domains 1-4, each composed of approximately 140 amino acid residues) of pig calpastatin were subcloned into E. coli plasmids to express the respective portions of the proteinase inhibitor gene in bacteria. Cell extracts of E. coli harboring recombinant plasmids were assayed for calpain inhibition. All four internally repetitive domains showed inhibitory activities, essentially similar to one another, against calpains I and II. No inhibition was observed in the case of the N-terminal non-homologous domain (domain L). These results support our previous conclusion that the repetitive region is a functional unit of the proteinase inhibitor.

Amino Acid Sequence↗
PubMed1987

Repetitive region of calpastatin is a functional unit of the proteinase inhibitor.

A cDNA portion coding for one of the repetitive regions of pig heart calpastatin (107 kDa) was subcloned into E. coli plasmid pUC119 to express the portion of the proteinase inhibitor gene in bacteria. The expressed protein was a chimaeric protein whose calpastatin segment (130 amino acid residues) was fused with an amino-terminus portion (7 amino acid residues) of beta-galactosidase. The chimaeric protein could inhibit proteolytic activity of calpain (Ca2+-dependent cysteine proteinase), and maintained properties of the authentic calpastatin concerning inhibition specificity and heat stability. These findings led us to conclude that the repetitive region is a functional unit of the proteinase inhibitor.

Amino Acid Sequence↗
PubMed1987

Clinical evaluation of antithrombin III concentrate (BI 6.013) for disseminated intravascular coagulation in obstetrics. Well-controlled multicenter trial.

Antithrombin III (AT III) is known to be the most important inhibitor of serine protease in the coagulation system. In the presence of heparin, AT III is converted from its progressive activity state to an immediate activity state. In disseminated intravascular coagulation (DIC) in the field of obstetrics, the treatment has to be initiated very early. Heparin treatment, on the other hand, is critical since frequently postpartal or postoperative wound bleeding is present. We, therefore, established diagnostic criteria for the early diagnosis of DIC and investigated the clinical efficacy of a therapy with AT III in a well-controlled comparative study versus the injectable synthetic protease inhibitor FOY. The results of the trial showed that the AT III group (92%; n = 24) was significantly (p less than 0.001) superior in clinical efficacy to the FOY group (60%; n = 15). No side effects whatsoever were observed after treatment with AT III concentrate (Behring Institute). From these results, it could be concluded that a single therapy with AT III concentrate can sufficiently control the symptoms of DIC in the field of obstetrics without the risk of increased bleeding.

Adult↗