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Biomedical subjects

H Kamada

Publications and source records attributed to H Kamada.

At least 91 records · Page 5Linked to original sources
PubMed1998

Vertigo secondary to hypotension: the relationship between therapeutic effects and hearing.

Patients with vertebrobasilar insufficiency tend to develop transient, repeated vertigo. However, diagnostic criteria by which to definitively diagnose circulatory disturbance of the vertebrobasilar system have yet to be established. Thus, in order to determine such criteria the relationship between the therapeutic effects on clinical symptoms and hearing in 40 patients with vertigo secondary to hypotension were investigated in the present study. In most patients, vertigo was perceived as a floating or spinning sensation which occurred spontaneously or during positional changes and lasted for a short period of time without hearing disturbance. Audiometry revealed bilateral low-frequency hearing loss or a tendency to low-frequency hearing loss in all patients. Low-frequency hearing loss is an important audiometric indication of vertebrobasilar insufficiency. Such hearing loss is very responsive to therapeutic circulatory agents and is considered to be an index for the evaluation of the effects of treatment for vertebrobasilar insufficiency.

Adenosine Triphosphate↗
PubMed1998

In vivo analysis of hydrogen peroxide and lipid radicals in the striatum of rats under long-term administration of a neuroleptic.

It has been hypothesized that free radicals play a causative role in tardive dyskinesia, which is an inveterate movement disorder caused by chronic administration of neuroleptics. To verify this hypothesis, rats were reared while being regularly treated with water containing a neuroleptic, haloperidol (HPD), for 1 year (HPD group). The changes in the striatal hydrogen peroxide content of the rats in the HPD and control groups were measured by using a Pt-disk microelectrode while the animals were in a freely moving state following intraperitoneal administration of HPD (HPD challenge). We also performed electron spin resonance (ESR) detection of lipid radicals in the striatum before the HPD challenge. HPD challenge led to significant elevation of the intrastriatal hydrogen peroxide in all animals, but the elevation in the HPD group was smaller than that in the control group. However, in the HPD group, marked ESR signals of intrastriatal lipid radicals were observed. We think that these results support the hypothesis on the role of free radicals in tardive dyskinesia.

Animals↗
PubMed1998

Non-invasive estimation of human left ventricular end-diastolic pressure.

Sato et al. (Electronic Letters 32, 949-950, 1996) reported that one can obtain a non-invasive estimate of left ventricular (LV) pressure at around end-diastole in an isolated canine preparation. In this study we examined whether this method can be applied to humans. Using the method proposed by Kanai et al. (IEEE. Trans. UFFC, 43, 791-810,1996), we detected small amplitude LV vibration from an ultrasonic pulse Doppler signal reflected from the interventricular septum in five patients (44-63 y.o., male;4, female;1). We measured the oscillation frequency of the LV wall through the wavelet transform of small amplitude LV vibration, and calculated LV pressure at around end-diastole from the values of oscillation frequency, internal radius and wall thickness using Mirsky's equation. The estimated LV pressures at around end-diastole were similar to end-diastolic pressure measured directly by cardiac catheterization. These results show the possibility that this method allows for the non-invasive estimate of LV pressure at around end-diastole, and furthermore provides the basis for future clinical applicability of this technique.

Adult↗
PubMed1998

C-ABI3, the carrot homologue of the Arabidopsis ABI3, is expressed during both zygotic and somatic embryogenesis and functions in the regulation of embryo-specific ABA-inducible genes.

A carrot gene homologous to the ABI3 gene of Arabidopsis was isolated from a carrot somatic embryo cDNA library and designated C-ABI3. The sequence of C-ABI3 was very similar to those of ABI3 of Arabidopsis and VP1 of maize in certain conserved regions. The expression of C-ABI3 was detected specifically in embryogenic cells, somatic embryos and developing seeds. Thus, expression of C-ABI3 was limited to tissues that acquired desiccation tolerance in response to endogenous or exogenous abscisic acid (ABA). Endogenous levels of ABA in seeds increased transiently and then desiccation of seeds started. The expression of C-ABI3 in developing seeds was observed prior to the increase in levels of endogenous ABA that was followed by desiccation of seeds. In transgenic mature leaves in which C-ABI3 was ectopically expressed, expression of ECP31, ECP63 and ECP40 was induced by treatment with ABA, which indicates that the expression of ECP genes was controlled by the pathway(s) that involved C-ABI3 and ABA. This suggests that C-ABI3 has the same function as VP1/ABI3 factor in carrot somatic embryos.

Abscisic Acid↗
PubMed1998

Patterns of expression of the genes for glutamine synthetase isoforms during somatic and zygotic embryogenesis in carrot.

Three cDNA clones encoding isoforms of carrot glutamine synthetase (GS) were isolated and used as probes for analysis of the patterns of expression of the genes for GS isoforms during somatic embryogenesis and seed development in carrot. Transcripts corresponding to two of the cDNAs, CGS102 and CGS201, accumulated in both somatic embryos and developing seeds in the same manner. Their levels were high at the early stage of embryogenesis but decreased at the late stage. This pattern of expression is similar to the pattern of changes in GS activity observed during somatic embryogenesis. In contrast, expression of the transcript for another GS isoform detected with CGS103 cDNA was observed at the late stage of seed development and in senesced leaves but not in somatic embryos or young leaves. We also analyzed the levels of the transcripts in somatic embryos that had been cultured in media with either ammonium ions or glutamine as the nitrogen source. The amounts of the CGS102 and CGS201 transcripts fell when glutamine was supplied in the medium. These results indicated that GS activity was regulated at the transcriptional level and that the pattern of expression of the genes for GS during somatic embryogenesis reflected that during zygotic embryogenesis. It is possible that somatic embryogenesis and zygotic embryogenesis have common regulatory systems with respect to nitrogen metabolism.

DNA, Complementary↗
PubMed1998

Accumulation of a clock-regulated transcript during flower-inductive darkness in pharbitis nil

To clarify the molecular basis of the photoperiodic induction of flowering in the short-day plant Pharbitis nil cv Violet, we examined changes in the level of mRNA in cotyledons during the flower-inductive photoperiod using the technique of differential display by the polymerase chain reaction. A transcript that accumulated during the inductive dark period was identified and a cDNA corresponding to the transcript, designated PnC401 (P. nil C401), was isolated. RNA-blot hybridization verified that levels of PnC401 mRNA fluctuated with a circadian rhythm, with maxima between 12 and 16 h after the beginning of the dark period) and minima of approximately 0. This oscillation continued even during an extended dark period but was damped under continuous light. Accumulation of PnC401 mRNA was reduced by a brief exposure to red light at the 8th h of the dark period (night-break treatment) or by exposure to far-red light at the end of the light period (end-of-day far-red treatment). These results suggest that fluctuations in levels of PnC401 mRNA are regulated by phytochrome(s) and a circadian clock and that they are associated with photoperiodic events that include induction of flowering.

Journal Article↗
PubMed1998

Spermine is a salicylate-independent endogenous inducer for both tobacco acidic pathogenesis-related proteins and resistance against tobacco mosaic virus infection

Intercellular spaces are often the first sites invaded by pathogens. In the spaces of tobacco mosaic virus (TMV)-infected and necrotic lesion-forming tobacco (Nicotiana tabacum L.) leaves, we found that an inducer for acidic pathogenesis-related (PR) proteins was accumulated. The induction activity was recovered in gel-filtrated fractions of low molecular mass with a basic nature, into which authentic spermine (Spm) was eluted. We quantified polyamines in the intercellular spaces of the necrotic lesion-forming leaves and found 20-fold higher levels of free Spm than in healthy leaves. Among several polyamines tested, exogenously supplied Spm induced acidic PR-1 gene expression. Immunoblot analysis showed that Spm treatment increased not only acidic PR-1 but also acidic PR-2, PR-3, and PR-5 protein accumulation. Treatment of healthy tobacco leaves with salicylic acid (SA) caused no significant increase in the level of endogenous Spm, and Spm did not increase the level of endogenous SA, suggesting that induction of acidic PR proteins by Spm is independent of SA. The size of TMV-induced local lesions was reduced by Spm treatment. These results indicate that Spm accumulates outside of cells after lesion formation and induces both acidic PR proteins and resistance against TMV via a SA-independent signaling pathway.

Journal Article↗
PubMed1998

In vivo three-dimensional EPR imaging of nitric oxide production from isosorbide dinitrate in mice.

Recently, in vivo electron paramagnetic resonance (EPR) spectroscopy and imaging have been widely used to investigate free radical distribution and metabolism in tissues, organs, and whole body of small animals. Endogenous nitric oxide (NO) is an attractive target of this method. In the present study, NO production from a nitrovasodilator, isosorbide dinitrate (ISDN), in live mice was investigated by in vivo EPR spectroscopy and imaging combined with the spin-trapping technique. A highly water-soluble Fe complex with N-(dithiocarboxy)sarcosine (DTCS) was used as an NO-trapping agent. Mice received [14N]-ISDN, and the Fe-DTCS complex subcutaneously exhibited the characteristic triplet EPR signal of the NO adduct [14NO-Fe(DTCS)2]2-. Using [15N]ISDN instead of [14N]ISDN, we were able to observe that the doublet EPR signal stemmed from the 15NO adduct, which directly demonstrated that NO was produced from ISDN. The three-dimensional EPR images of the upper abdomen of living mice showed that the NO adducts were distributed in the liver and the kidneys. This EPR image combined with the ex vivo EPR measurements of the blood suggested that NO production from ISDN occurred in the liver in this experimental condition.

Animals↗
PubMed1998

Effect of dietary selenium supplementation on the plasma progesterone concentration in cows.

ABSTRACT. The effect of selenium (Se) supplementation to the diet on the plasma progesterone concentration was investigated in non-lactating and non-pregnant cows. Italian ryegrass wafers and concentrates, with or without 0.5 ppm of Se, were fed to cows at a maintenance level. The plasma Se concentrations in the each treatment were 0.047 ppm (-Se) and 0.081 ppm (+Se), respectively. Se supplementation did not affect the length of the estrous cycle, but it did increase the concentration of plasma progesterone in the estrous cycle (P<0.001). These results suggest the possibility that Se contributes to the progesterone production of corpus luteum.

Analysis of Variance↗
PubMed1998

[Probability of leaving cancer tissue unresected by limited operation in patients with peripheral, stage I non-small cell lung cancer].

To study the probability of leaving metastatic lymph nodes or intralobar metastasis unresected by limited surgery, we reviewed histopathologically 189 patients who had major pulmonary resection and complete lymph adenectomy for peripheral, p-T 1 or T 2 non-small cell lung cancer from 1975 to 1997 at our hospital. Lymph node involvements and or intralobar metastasis were found in 25 (26.0%) of 96 cases with tumor smaller than 3.0 cm and 44 (47.3%) of 93 cases with tumor larger than 3.0 cm. There was no difference between histological types of lung cancer. From this result, it was suggested that the risk of leaving cancer by limited operation would not be low. In conclusion, we believe that limited operation is not an alternative to the standard resection in patients with peripheral, stage I non-small cell lung cancer.

Aged↗
PubMed1998

[Neural protective agents, propentofylline (PPF) could induce apoptotic cell death in the human glioma cells: analysis of Bcl-2 and Bax alpha/Bax beta expressions].

In the previous study, we have shown that propentofylline (PPF) could induce the cellular differentiation and apoptosis-related growth regression in the human glioma cell lines. Its biological functions were partly due to the increasing endogeneous NGF and its high affinity receptor, trk A productions. Although little has been known about the precise machinary regulating the propentofylline induced apoptosis. Recently, we have found that propentofylline could modulate some apoptosis related genes products in the glioma cell lines, i.e. NGF, trk A mRNA levels and Fas protein expressions were increased, whereas bcl-2 mRNA level was decreased. In the present study, we examined the apoptotic signal cascade, especially focusing on the expressing pattern of Bcl-2/Bax gene products. In the normal human astrocyte cells, Bax-beta was markedly expressed, whereas Bcl-2 and Bax-alpha proteins and mRNA were weakly or even nondetectable. Accordingly, Bax beta might be a dominant variant in the normal glial cells, which could have the appropriate balance of proapoptotic (Bax beta) and anti-apoptotic proteins (Bcl-2). In the glioma cells, we showed the over-expressions of Bcl-2 and Bax alpha compared with the normal counterparts. According to Bax dominant theory, Bax, not Bcl-2 may have a major role in regulating apoptosis by means of homodimerization. In might be implied that in the glioma cells, excessive expressions of Bcl-2 and Bax alpha would favor the formation of the Bax alpha/Bax beta heterodimer or the Bax beta/Bcl-2 heterodimer rather than the Bax beta/Bax beta homodimer, which might be presumed to be functional proteins. And finally the increasing relative ratio of Bax alpha/ Bax beta or Bax beta/Bcl-2 to Bax beta/Bax beta could allow the tumor cells to survive. Thus over-expression of the bcl-2 and bax alpha gene renders the glioma cells resistant to apoptosis. In the present study, PPF could promote Bax beta over-expression and Bcl-2 retardative expression in the glioma cells, whereas had no effect on Bax alpha expression. Therefore, PPF might promote apoptotic cell death through the mechanism that restore the glioma cells to the appropriate balance of proapoptotic and anti-apoptotic proteins like as normal astrocytes. Our results indicated that propentofylline might have a potential role as apoptotic modulators in the human glioma cell lines, not only its protective activities against neuronal ischemic damages.

Apoptosis↗
PubMed1998

[Induction of apoptosis through NGF/p75NTR in human glioma cells treated with propentofylline].

Propentofylline (PPF) is a xanthine derivative and it has been reported that PPF stimulated the synthesis/secretion of nerve growth factor (NGF) by cultured astroglial cells. We have reported that PPF induced apoptosis in human glioma cells and as its mechanism, up-regulation of NGF, Fas, Bax beta and down-regulation of Bcl-2 were assumed. Recent studies demonstrated the presence of apoptosis induced via NGF/p75NTR in developmental neuron, oligodendroglia. In the present study, to examine whether signal cascade via NGF/p75NTR participates the apoptosis in human glioma cells treated with PPF, we investigated the immunohistochemical study using anti-mouse monoclonal antibody, immunoprecipitation and northern blot analysis for p75NTR, NF-kappa B in human glioma cells (U251MG, T98G, U87) treated with PPF. We observed the up-regulation of p75NTR, translocation of NF-kappa B to the nucleus after treatment with PPF in these cell lines. According to above results, it is assumed that apoptosis in human glioma cells treated with PPF was induced via NGF/p75NTR.

Apoptosis↗
PubMed1997

Bioconjugation of tumor necrosis factor-alpha with the copolymer of divinyl ether and maleic anhydride increasing its antitumor potency.

To enhance the therapeutic usefulness of antitumor cytokines in vivo, we synthesized bioconjugated tumor necrosis factor-alpha (TNF-alpha) with divinyl ether and maleic anhydride copolymer (DIVEMA), which has intrinsic antitumor activity as a synthetic biological response modifier. The degree of modification could be controlled by the addition of 2,3-dimethylmaleic anhydride (DMMAn), which binds to amino groups of TNF-alpha by changing the pH. In addition, the specific activity of DIVEMA-TNF-alpha was hardly decreased in vitro. DIVEMA-TNF-alpha showed a marked antitumor effect compared to native TNF-alpha without any side effects such as sudden death, body-weight reduction, and decrease in platelet count on mice bearing solid tumors. These results suggest that DIVEMA is a useful polymeric modifier for-bioconjugation of TNF-alpha in order to increase its antitumor activity, and multifunctionally bioconjugated TNF-alpha may be a potentiated antitumor agent for therapeutic use.

Animals↗
PubMed1997

The origin of an EPR signal observed in dithiocarbamate-loaded tissues. Copper(II)-dithiocarbamate complexes account for the narrow hyperfine lines.

We examined the electron paramagnetic resonance spectra of some copper(II)-dithiocarbamate complexes in various media at liquid nitrogen temperature. It is demonstrated that Cu(II)-dithiocarbamate complexes exhibit atypical spectra with narrow hyperfine splitting, and that the dithocarbamates forming a water-insoluble Cu(II) complex are permeable in tissues, while those yielding water-soluble complexes are not.

Animals↗
PubMed1997

Arabidopsis thaliana ECP63 encoding a LEA protein is located in chromosome 4.

DCECP63 is a carrot embryogenic cell protein. To perform its genetic analysis, we isolated an Arabidopsis thaliana (At) ECP63 cDNA. The cDNA encoded a polypeptide of 449 amino acids (aa). Its deduced aa sequence showed extensive similarity with DCECP63, DCDC8 and BPBP8 which are embryonic proteins isolated from carrot and birch, respectively. The aa sequence contained eight well-conserved tyrosine phosphorylation sites and 16 repeats of 11 aa. Southern analysis showed that the AtECP63 gene might belong to a small multigene family. The AtECP63 transcripts accumulated specifically in mature seeds, and exogenous abscisic acid (ABA) induced its expression in immature siliques, but not in vegetative tissues. These results suggested that the AtECP63 gene encoding a putative phosphotyrosine protein belonging to late embryogenesis abundant (LEA) protein in group 3 might be involved in maturation and desiccation tolerance of seeds. Restriction fragment length polymorphism (RFLP) and cleaved amplified polymorphic sequence (CAPS) mapping showed that AtECP63 gene was present in the South part of chromosome 4.

Amino Acid Sequence↗
PubMed1997

In vivo longitudinally detected ESR measurements at microwave regions of 300, 700, and 900 MHz in rats treated with a nitroxide radical.

A signal detector of longitudinally detected ESR (LODESR) is independent of the resonant frequency. We developed an in vivo LODESR spectrometer operating in the regions of 300, 700, and 900 MHz. Using this apparatus, we estimated signal intensities at different operating frequencies obtained from non- or high-dielectric loss phantoms that contained nitroxide radical solutions and from live rats that had received a nitroxide radical. Our result, higher signal intensities in the high-dielectric loss samples (such as physiological saline solution and animals) at a lower frequency, shows that the influence of a decrease in dielectric loss dominates over the signal reduction caused by smaller Zeeman splitting. We believe that this finding strongly supports an in vivo ESR resonant frequency that tends to be low.

Animals↗
PubMed1997

Dimeric tubulin-stimulated adenylyl cyclase activity is augmented after long-term amitriptyline treatment.

We have investigated altered association of tubulin dimers interacting with G proteins and modulating adenylyl cyclase (AC) as a result of long-term amitriptyline (AMT) treatment. Gpp(NH)p-stimulated, but not basal or manganese-stimulated, AC activity was significantly augmented in cortex membranes prepared from rats chronically treated with AMT. The enhancement of AC activity by Gpp(NH)p-liganded tubulin (tubulin-Gpp(NH)p) was significantly higher in chronically AMT-treated rats than in control rats. Moreover, in cortex membranes from controls, tubulin-Gpp(NH)p prepared from chronically AMT-treated rats was more effective to activate AC activity than tubulin-Gpp(NH)p from controls. Immunoblotting and photoaffinity guanine nucleotide binding procedures showed no significant differences in the amount and the function of G proteins between controls and AMT-treated groups. It is suggested that long-term AMT treatment causes alteration in the functional interaction between tubulin and G protein, and this modification may participate in enhanced coupling of Gs to the catalytic subunit of AC induced by the chronic antidepressant treatment.

Adenylyl Cyclases↗