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Biomedical subjects

H Hama

Publications and source records attributed to H Hama.

At least 73 records · Page 4Linked to original sources
PubMed1993

Arthroscopic multiple osteochondral transplantation to the chondral defect in the knee associated with anterior cruciate ligament disruption.

Treatment of a chondral lesion in the knee, associated with anterior cruciate ligament disruption, is known to be difficult and controversial. This article presents an arthroscopic technique for transplantation of multiple osteochondral fragments, harvested from the same knee, to this chondral lesion. A 3-year follow-up shows excellent results with good cartilage repair confirmed by second-look arthroscopy.

Adult↗
PubMed1993

High prevalence of anti-cardiolipin antibody, C1q-, C3d-, and mRF-IgG immune complexes, and anti-nuclear antibody in hemophiliacs irrespective of infection with human immunodeficiency virus type 1.

We investigated the prevalence of various autoantibodies [anti-cardiolipin antibody (aCL), lupus anticoagulant (LA), immune complexes (ICs), anti-nuclear antibody (ANA), and anti-deoxyribonucleic acid antibody (aDNA)] in hemophiliac individuals with (n = 50) and without (n = 42) infection by human immunodeficiency virus type 1 (HIV-1). The positivity rate for ANA was similar in both groups, and none of the patients was positive for LA and aDNA. aCL was positive in 35 of 50 (70%) HIV-1-positive hemophiliac individuals and 33 of 42 (79%) HIV-1-negative hemophiliac individuals. However, the majority of the aCL was revealed to be beta 2-glycoprotein I independent, thus corresponding to a syphilis type aCL that does not cause the so-called antiphospholipid syndrome. A total of 39 of the 45 HIV-1 positive hemophiliac individuals (87%) and 34 of 41 HIV-1-negative hemophiliac individuals (83%) had at least one type of IC [C1q-, C3d-, and/or murine monoclonal rheumatoid factor (mRF)- IgG]. The mechanism producing various autoantibodies in hemophiliac persons irrespective of their HIV-1 status is still unclear, but pathogens (e.g., HIV-1, hepatitis B, and hepatitis C) and alloantigens in the blood products that these patients require may be possible candidates. The clinical significance of the presence of these autoantibodies and the underlying mechanisms involved both need to be clarified further.

Antibodies, Anticardiolipin↗
PubMed1992

Primary structure and characteristics of the melibiose carrier of Klebsiella pneumoniae.

The melB gene coding for the melibiose carrier of Klebsiella pneumoniae was cloned and sequenced. There were two potential translation initiation sites. It was predicted that the melibiose carrier consists of 471 (or 467) amino acid residues. Seventy-eight percent of the 471 amino acids were identical to the Escherichia coli melibiose carrier. Sugar transport characteristics were studied using an E. coli mel- mutant expressing cloned K. pneumoniae melB gene. Accumulation of melibiose via the K. pneumoniae melibiose carrier was not stimulated by adding NaCl or LiCl which stimulates melibiose accumulation via the E. coli melibiose carrier. Lactose was accumulated only in the presence of LiCl. TMG (methyl-1-thio-beta-D-galactopyranoside) was accumulated in the absence of added NaCl or LiCl. The accumulation was stimulated by LiCl but not by NaCl. Rapid H+ uptake was observed when melibiose or TMG was added to cell suspensions. These results suggest that the preferred cation couplings via K. pneumoniae melibiose carrier are H(+)-melibiose, Li(+)-lactose, and H+/Li(+)-TMG. This coupling spectrum is quite different from that of the E. coli melibiose carrier. It is of special interest that the K. pneumoniae melibiose carrier seems to be lacking the ability to recognize Na+ which is a preferred coupling cation of the E. coli melibiose carrier for all known sugar substrates. Further investigation of these two carriers may give us insight into the Na+ recognition site.

Amino Acid Sequence↗
PubMed1992

Action of endothelin-1 on rat astrocytes through the ETB receptor.

We investigated the effect of ET-1 on the state of rat cerebral astrocytes (AC) differentiation. AC ceased to proliferate and changed into its differentiated state by treatment with dibutyryl cyclic AMP (DBcAMP). The cell growth activity in DBcAMP-treated AC was stimulated by ET-1 in a dose-dependent manner. Over similar dose ranges, ET-1 suppressed the glutamine synthetase activity in DBcAMP-treated AC. The molar potency of ET-1 in this action was at least 3 orders of magnitude higher than that in mitogenic action in AC under the proliferative state previously reported. Northern blot analysis revealed that ETB receptor mRNA level in DBcAMP-treated AC was markedly higher than that in AC untreated with DBcAMP. Consistently, binding studies showed that the Bmax value for [125I]ET-1 in DBcAMP-treated AC was 16 times higher than that in AC untreated with DBcAMP. These results suggest that ET-1 potently induced a retraction of the differentiation state of AC from fully the specialized state and that the high responsiveness of differentiated AC to ET-1 was partly attributed to the high level expression of the ETB receptor.

Animals↗
PubMed1992

Urinary excretion of 3,4-dimethylhippuric acid in workers exposed to 1,2,4-trimethylbenzene.

The urinary excretion of 3,4-dimethylhippuric acid (34DMHA), a 1,2,4-trimethylbenzene (124TMB) metabolite, was investigated in workers exposed to 124TMB vapor. The time-weighted average of exposure to 124TMB was determined with a diffusive sampler. For biological monitoring of exposure, urine samples were collected from individual workers and analyzed for metabolites by high-pressure liquid chromatography. The concentration of urinary 34DMHA had a positive correlation with the level of exposure to 124TMB (r = 0.72). The data suggest that 34DMHA is one of the useful indicators for biological monitoring of 124TMB exposure.

Air Pollutants, Occupational↗
PubMed1992

Effect of dopamine injection into the anteroventral third ventricular region and the paraventricular nucleus on vasopressin secretion in conscious rats.

To investigate the role of dopamine receptors situated in the paraventricular nucleus and the anteroventral third ventricular region in regulating vasopressin release, responses of plasma AVP and its controlling factors to injections of dopamine into these regions and the lateral cerebral ventricle were examined in conscious rats. The injections of 156 nmol (30 micrograms) dopamine into the cerebral ventricle produced transient rises in plasma AVP 5 min later. When the dose of dopamine was reduced to 26 nmol (5 micrograms), the increase in plasma AVP was not provoked any more. However, injections of 26 nmol dopamine into the paraventricular nucleus greatly augmented plasma AVP 5 and 15 min later. This dose of dopamine was without effect on plasma AVP when injected into the anteroventral third ventricular region, including the organum vasculosum lamina terminalis, median preoptic nucleus, medial preoptic area and the periventricular preoptic nucleus. These dopamine administrations in the cerebral ventricle, paraventricular nucleus and the anteroventral third ventricular region did not significantly change AVP-controlling factors such as plasma osmolality, sodium and arterial pressure. On the basis of these results, we conclude that dopamine receptors in the paraventricular nucleus may function to facilitate AVP secretion, whereas those in the anteroventral third ventricular region may not play an important role in the regulation of AVP release.

Animals↗
PubMed1991

Separation of periventricular dopaminergic and alpha-adrenergic systems from the vasopressin-secreting mechanisms activated by prostaglandin D2.

The aim of this study was to evaluate periventricular dopaminergic and alpha-adrenergic receptor functions in vasopressin (AVP) secretion elicited by central applications of prostaglandin D2 (PGD2) in conscious rats. Intracerebroventricular (i.c.v.) injections of PGD2 (70.9 nmol (25.0 micrograms] produced transient rises in plasma AVP 5 min later, without increasing plasma osmolality, sodium and hematocrit. Arterial pressure and heart rate before and after the PGD2 administrations were not significantly different from those of control rats receiving its vehicle. The PGD2-induced AVP response was not significantly altered by the prior i.c.v. administrations (0.15 mumol) of dopamine receptor antagonists, SCH 23390 or sulpiride, and an alpha-adrenoreceptor antagonist, phenoxybenzamine, performed 10 min before the injections of PGD2. The pretreatments with these catecholamine antagonists were confirmed to significantly prevent the augmentations in plasma AVP 5 min after the i.c.v. applications of 0.75 mumol dopamine or phenylephrine that were considerably larger than the PGD 2-induced AVP response. From these results, we concluded that dopaminergic and alpha-adrenergic receptors in the periventricular regions may not be involved in the AVP secretion stimulated by PGD2.

Animals↗
PubMed1991

Nucleoside diphosphate kinase from Escherichia coli; its overproduction and sequence comparison with eukaryotic enzymes.

The gene encoding nucleoside diphosphate (NDP) kinase of Escherichia coli was identified by polymerase chain reaction using oligodeoxyribonucleotide primers synthesized on the basis of consensus sequences from Myxococcus xanthus and various eukaryotic NDP kinases. The gene (ndk), mapped at 54.2 min on the E. coli chromosome, was cloned and sequenced. The E. coli NDP kinase was found to consist of 143 amino acid residues that are 57, 45, 45, 42, 43, and 43% identical to the M. xanthus, Dictyostelium discoideum, Drosophila melanogaster, mouse, rat, and human enzymes, respectively. The ndk gene appears to be in a monocistronic operon and, when cloned in a pUC vector, NDP kinase was overproduced at a level of approx. 25% of total cellular proteins. The protein could be labeled with [gamma-32P]ATP and migrated at a 16.5 kDa when electrophoresed in SDS-polyacrylamide gel, which is in good agreement with the Mr of the purified E. coli NDP kinase previously reported.

Amino Acid Sequence↗
PubMed1991

Sequence analysis of nutA gene encoding membrane-bound Cl(-)-dependent 5'-nucleotidase of Vibrio parahaemolyticus.

The membrane-bound 5'-nucleotidase of Vibrio parahaemolyticus is unique in requiring Cl- for activity. We cloned the nutA gene encoding the 5'-nucleotidase and sequenced it. It contained an open reading frame consisting of 1,680 nucleotides capable of encoding a protein of 560 amino acid residues. The first 21 amino acid residues of the N-terminal portion of this protein seem to be a signal peptide. The rest of the polypeptide (539 residues) is hydrophilic, and its molecular weight was calculated to be 60,008, which is in good agreement with the value of 63 kDa determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis for the 5'-nucleotidase derived from the cloned nutA gene. We tried to determine the amino acid sequence of the N-terminal portion of the purified enzyme. However, the N-terminal residue seemed to be blocked. As this 5'-nucleotidase can be solubilized from membrane vesicles with detergent, it may be a lipoprotein. The amino acid sequence around the possible cleavage site of the 5'-nucleotidase had homology with the sequences of the cleavage sites of the lipoproteins of Escherichia coli and other bacteria. The amino acid sequence had high (about 60%) homology with the sequence of periplasmic 5'-nucleotidase (uridine diphosphate sugar hydrolase, the product of the ushA gene) of E. coli. It also contained regions that showed some homology with the nucleotide binding sites of many nucleotide binding proteins.

5'-Nucleotidase↗
PubMed1991

Inhibition of homoserine dehydrogenase I by L-serine in Escherichia coli.

We have reported that a major cause of growth inhibition of Escherichia coli by L-serine is its inhibition of homoserine dehydrogenase I (HDH I), which is involved in the biosyntheses of threonine and isoleucine [Hama, H., Sumita, Y., Kakutani, Y., Tsuda, M., & Tsuchiya, T. (1990) Biochem. Biophys. Res. Commun. 168, 1211-1216]. However, Patte et al. reported that L-serine does not inhibit HDH I [Patte, J.-C., Truffa-Bachi, P., & Cohen, G.N. (1966) Biochim. Biophys. Acta 128, 426-439]. In studies on the reason for these discrepant results, we found that the concentration of K+ and the pH in the assay mixture strongly influenced the inhibitory effect of L-serine. L-Serine strongly inhibited the HDH I activities in both the forward and reverse reactions between aspartate semialdehyde and homoserine at a physiological K+ concentration (100 to 200 mM) and physiological pH (7.5) for E. coli cells. On the other hand, two well-known inhibitors of HDH I, L-threonine and L-cysteine, strongly inhibited the activity regardless of the K+ concentration and pH.

Cations, Monovalent↗
PubMed1991

Participation of periventricular dopamine receptors in vasopressin secretion elicited by hypertonicity of systemic blood in rats.

The aim of this study was to examine in conscious rats the role of periventricular dopamine receptors in vasopressin secretion caused by hypertonicity of the systemic blood. Intracerebroventricular injections of dopamine (0.15 or 0.75 mumol) produced dose-related increases in plasma AVP 90 sec or 5 min later, without affecting plasma osmolality, concentrations of electrolytes, hematocrit, arterial pressure or heart rate. The AVP response to 0.75 mumol dopamine was blocked by its antagonists, SCH 23390, sulpiride and haloperidol, given intracerebroventricularly at a dose of 0.15 mumol 10 or 40 min before the injection of dopamine. The ip injections (2 ml/100 g) of 600 mmol/l NaCl produced, 15 or 30 min later, augmentations in plasma AVP accompanied by elevations in plasma osmolality, sodium and chloride. At a dose of 0.15 mumol given intracerebroventricularly 10 min before the injection of 600 mmol/l NaCl, SCH 23390 or sulpiride inhibited the AVP response at 15 min, and sulpiride or haloperidol inhibited that at 30 min. The increases in plasma osmolality and the electrolytes owing to hypertonic saline were not reduced by these dopamine antagonists. The intracerebroventricular applications of the antagonists followed by those of vehicles for dopamine or by ip injections of 150 mmol/l NaCl were without any effect on plasma AVP or the other plasma variables. On the basis of these results, we concluded that dopamine receptors in the periventricular regions may contribute to AVP secretion in response to hypertonicity of the systemic blood.

Animals↗
PubMed1990

Target of serine inhibition in Escherichia coli.

L-serine has long been known to inhibit growth of Escherichia coli cells cultured in minimal medium supplemented with glucose, lactate, or another carbohydrate as the sole source of carbon. However, the target of serine inhibition was not known. The growth inhibition was released by adding isoleucine, 2-ketobutyric acid, threonine or homoserine, but not by aspartate. Thus the inhibition site must be between aspartate and homoserine in the isoleucine biosynthetic pathway. We found that homoserine dehydrogenase I was strongly inhibited by serine. We isolated serine-resistant mutants, and found that in these mutants homoserine dehydrogenase I was resistant to serine. Thus, we conclude that the target of serine inhibition in Escherichia coli is homoserine dehydrogenase I.

Alcohol Oxidoreductases↗
PubMed1990

Inhibitory role of periventricular dopaminergic mechanisms in hemorrhage-induced vasopressin secretion in conscious rats.

Acute blood loss (16 ml/kg b. wt.) in conscious rats caused, 5 min later, increases in plasma vasopressin (AVP) concentration accompanied by reductions in arterial pressure and hematocrit. The plasma AVP response was markedly enhanced by intracerebroventricular injection (10 microliters) of a dopamine antagonist, haloperidol (0.15 mumol), which did not affect the responses of arterial pressure and hematocrit significantly. These results suggest that periventricular dopaminergic mechanisms may act to inhibit hemorrhage-induced AVP secretion.

Animals↗
PubMed1990

Finger-pressure waveforms measured on Clynes' Sentograph distinguish among emotions.

We examined the transient finger-pressure when subjects were exposed to the schematic faces which depict "anger," "joy," "sadness," and "no emotion," and to two nonfacial stimuli. In Exp. 1, nine undergraduate women were asked to discriminate between those target stimuli and the nontarget stimuli by pressing on the finger rest of Clynes' Sentograph, without informing subjects that this experiment was to measure emotions. In Exp. 2, the same subjects were asked to express their feelings evoked by the schematic faces by pressing on the finger rest. Results indicate that, even on the discrimination task, the differentiation in the finger-pressure waveforms among emotions was observed. Such differentiation suggests the possibility of measuring the expression of emotions with finger pressure even when the subjects are not aware their emotions are being measured. The identifiable characteristics of the waveforms are the long duration for "sadness" and the strong intensity of pressure for "anger."

Adult↗