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Biomedical subjects

M Konishi

Publications and source records attributed to M Konishi.

At least 109 records · Page 6Linked to original sources
PubMed1998

Transient expression and transport of brain-derived neurotrophic factor in the male zebra finch's song system during vocal development.

The distribution of brain-derived neurotrophic factor (BDNF) in the song system of male zebra finches changes with posthatching age. At day 20, the hyperstriatum ventrale, pars caudale is the only song nucleus in which neurons showed BDNF immunoreactivity. At day 45, the staining in hyperstriatum ventrale, pars caudale was denser than at day 20 and the robust nucleus of the archistriatum, another song nucleus, showed BDNF labeling. By day 65, two additional song nuclei, area X and the lateral magnocellular nucleus of the anterior neostriatum, have become immunoreactive. In the adult, however, the amount of BDNF labeling in all of these brain nuclei is sharply reduced. These sequential events, the anatomical connections between these song nuclei, and the labeling of relevant axons and terminals suggest anterograde transport of BDNF. Furthermore, the timing of BDNF expression coincident with the development of singing behavior suggests that this neurotrophin may be directly involved with the differentiation of the song system.

Age Factors↗
PubMed1998

Infrequent somatic mutation of the adenomatous polyposis coli gene in aberrant crypt foci of human colon tissue.

BACKGROUND: The authors examined somatic mutations of the adenomatous polyposis coli (APC) gene in 84 human aberrant crypt foci (ACF) to determine whether APC gene mutations were involved in the histologic progression of ACF. METHODS: Mutation cluster regions of the APC gene were subjected to polymerase chain reaction single-strand conformation polymorphism analysis and direct sequencing. RESULTS: Four kinds of deletion were detected in the mutation cluster regions of APC gene in five ACF. APC mutation was detected in 1 of 18 ACF with Stage I abnormalities (6%). Four of 10 adenomatous ACF (40%) harbored the mutation. There were no mutations in 56 hyperplastic ACF. CONCLUSIONS: These results suggest that APC mutations may be involved initially in only a limited number of adenomas in ACF.

Adenomatous Polyposis Coli↗
PubMed1998

How do owls localize interaurally phase-ambiguous signals?

Owls and other animals, including humans, use the difference in arrival time of sounds between the ears to determine the direction of a sound source in the horizontal plane. When an interaural time difference (ITD) is conveyed by a narrowband signal such as a tone, human beings may fail to derive the direction represented by that ITD. This is because they cannot distinguish the true ITD contained in the signal from its phase equivalents that are ITD +/- nT, where T is the period of the stimulus tone and n is an integer. This uncertainty is called phase-ambiguity. All ITD-sensitive neurons in birds and mammals respond to an ITD and its phase equivalents when the ITD is contained in narrowband signals. It is not known, however, if these animals show phase-ambiguity in the localization of narrowband signals. The present work shows that barn owls (Tyto alba) experience phase-ambiguity in the localization of tones delivered by earphones. We used sound-induced head-turning responses to measure the sound-source directions perceived by two owls. In both owls, head-turning angles varied as a sinusoidal function of ITD. One owl always pointed to the direction represented by the smaller of the two ITDs, whereas a second owl always chose the direction represented by the larger ITD (i.e., ITD - T).

Animals↗
PubMed1998

Structure and expression of a novel fibroblast growth factor, FGF-17, preferentially expressed in the embryonic brain.

We isolated the cDNA encoding a novel member (216 amino acids) of the fibroblast growth factor (FGF) family from rat embryos. As this protein is the 17th documented member of the FGF family, we tentatively termed it FGF-17. We have also determined the structures of mouse and human FGF-17 with high amino acid identity (100 and 98.6%) to rat FGF-17, respectively. Among FGF family members, FGF-17 is most similar (53.7% amino acid identity) to FGF-8. FGF-17 has a typical signal sequence at its amino terminus. As expected, recombinant rat FGF-17 was efficiently secreted by High Five insect cells infected with recombinant baculovirus containing the cDNA indicating that FGF-17 is a secreted protein. FGF-17 mRNA of approximately 2.1 kb was detected in rat embryos at E14.5, but not at E10.5 and E19.5 by Northern analysis. The mRNA was found to be preferentially expressed in the neuroepithelia of the isthmus and septum of the rat embryonic brain at E14.5 by in situ hybridization. The present results indicate that FGF-17 might be a novel secreted signaling molecule in the induction and patterning of the embryonic brain.

Amino Acid Sequence↗
PubMed1998

Structure and expression of a novel member, FGF-16, on the fibroblast growth factor family.

We have isolated cDNA encoding a novel member (207 amino acids) of the FGF family from the rat heart by homology-based polymerase chain reaction. As this protein is the 16th documented member of the FGF family, we tentatively term it FGF-16. Among FGF family members, FGF-16 is most similar (73% amino acid identity) to FGF-9. We have also determined the structure of human FGF-16 with high amino acid sequence identity (98.6%) to rat FGF-16. Although the predicted FGF-16 amino acid sequence lacks a typical signal sequence, recombinant rat FGF-16 was efficiently secreted by Sf9 insect cells infected with recombinant baculovirus containing the cDNA. FGF-16 mRNA was predominantly expressed in the rat heart among the adult major tissues examined. The expression profile of FGF-16 mRNA was quite different from those of other members of the FGF family. In rat embryos, FGF-16 mRNA was predominantly expressed in the brown adipose tissue. However, the expression decreased greatly after birth. These results indicate that FGF-16 in embryos might play a role in development of the brown adipose tissue.

Adipose Tissue, Brown↗
PubMed1998

Clinicopathologic and genetic features of nonfamilial colorectal carcinomas with DNA replication errors.

BACKGROUND: DNA replication errors (RERs) are closely associated with hereditary nonpolyposis colorectal carcinoma (HNPCC). Recently, alterations in DNA mismatch repair genes, including hMSH2, hMLH1, and hPMS2, have been implicated in the pathogenesis of HNPCC: Several studies have demonstrated RER in 13-17% of nonfamilial colorectal carcinomas. It is unclear, however, as to whether or not these RER positive nonfamilial colorectal carcinomas are incomplete forms of HNPCC or are caused by incidental alterations of DNA mismatch repair genes. Consequently, the authors studied the characteristics of RER positive nonfamilial colorectal carcinomas, placing particular emphasis on hMSH2 and hMLH1 gene mutations. METHODS: Fresh or frozen samples of 103 nonfamilial colorectal carcinomas were examined for RERs using the polymerase chain reaction (PCR) and specific microsatellite primers. The authors also identified mutations of the hMSH2 and hMLH1 genes in RER positive samples by a PCR single strand conformational polymorphism analysis followed by direct nucleotide sequencing. RESULTS: The incidence of RER was 15.7% (17/103) in nonfamilial colorectal carcinomas, and only 1 case, which was found in the ascending colon, showed a somatic mutation at exon 12 in the hMSH2 gene. Neither germline nor somatic mutations of the hMSH2 or hMLH1 genes could be found in any of the remaining RER positive tumors. RER positive nonfamilial carcinomas tended to be located more frequently in the right colon. There was no increased prevalence in young patients, and the clinicopathologic characteristics of HNPCC were absent in the patients with RER positive nonfamilial colorectal carcinoma. CONCLUSIONS: Based on these findings, the carcinogenesis of RER positive nonfamilial colorectal carcinoma is considered different from that of HNPCC:

Adaptor Proteins, Signal Transducing↗
PubMed1998

Estimation of myofibrillar responsiveness to Ca2+ in isolated rat ventricular myocytes.

To estimate myofibrillar responsiveness to Ca2+, we used the relation between cell length and intracellular [Ca2+] ([Ca2+]i) during tetanic contractions of isolated ventricular myocytes. Enzymatically isolated rat ventricular myocytes were loaded with fura-2 AM (4 microM for 10 min) and excited alternately at 340 nm and 380 nm. The ratio (R) of fura-2 fluorescence at these wavelengths [F(340)/F(380), an index of [Ca2+]i] and cell length (L) were measured simultaneously. Following treatment with thapsigargin (0.2 microM), myocytes were stimulated at 10 Hz for 10 s to produce a tetanic contraction every min and an instantaneous plot of R vs L (R-L trajectory) was constructed. The R-L trajectory followed the same path during cell shortening and re-lengthening, suggesting that dynamic equilibrium between R and L was achieved during tetanus. Increasing the extracellular [Ca2+] from 1 to 8 mM extended the R-L trajectory without a substantial shift of the relation. The Ca2+-sensitizing thiadiazinone derivative, EMD57033 (1 microM), shifted the R-L trajectory to the left (sensitization of the myofibrils to Ca2+), whereas the non-selective phosphodiesterase inhibitor, 3-isobutyl-1-methylxantine (200 microM), shifted the R-L trajectory to the right (desensitization of the myofibrils to Ca2+), in agreement with previous results obtained using skinned preparations. We conclude that the R-L trajectory is useful for estimating the myofibrillar responsiveness to Ca2+ in isolated myocytes and may be beneficial for the evaluation of inotropic agents.

1-Methyl-3-isobutylxanthine↗
PubMed1998

The classic form of granular corneal dystrophy associated with R555W mutation in the BIGH3 gene is rare in Japanese patients.

PURPOSE: To identify the BIGH3 gene mutation in 10 unrelated Japanese individuals with granular corneal dystrophy. METHODS: Genomic DNA was obtained from each patient's leukocytes. Exons 4 and 12 of the BIGH3 gene were amplified by polymerase chain reaction and were directly sequenced. RESULTS: Nine of these patients were found to have the R124H mutation, whereas only one had the R555W mutation. Slit-lamp examination showed that the granular corneal dystrophy associated with each mutation is different. CONCLUSIONS: These results, together with our previous findings, show that the classic form of granular corneal dystrophy associated with the R555W mutation is rare in Japanese patients, whereas granular corneal dystrophy accompanied by amyloid deposits and associated with the R124H mutation, Avellino corneal dystrophy, is more common. Direct examination may be insufficient in the proper diagnosis of corneal dystrophy, and BIGH3 mutation analysis may be required.

Adult↗
PubMed1998

Corneal ulcer associated with deposits of norfloxacin.

PURPOSE: To report a case of corneal ulcer associated with deposits of norfloxacin. METHOD: Case report. A 40-year-old man with right trigeminal and facial nerve palsies and decreased tear secretion developed a corneal ulcer with white deposits in the right eye. The deposits were removed and analyzed by high-performance liquid chromatography. RESULTS: High-performance liquid chromatography results disclosed that the deposits on the corneal surface had the same retention time as norfloxacin. The patient discontinued norfloxacin ophthalmic solution and recovered successfully. CONCLUSION: Clinicians should be aware that frequent applications of topical norfloxacin in patients with decreased tear secretion may result in deposition of the drug on the cornea.

Adult↗
PubMed1998

Ovarian dysgerminoma showing high serum levels and positive immunostaining of placental alkaline phosphatase and neuron-specific enolase associated with elevation of serum prolactin level.

We report a 35-year-old Japanese female patient with ovarian dysgerminoma showing elevated serum levels of placental alkaline phosphatase (PLAP), neuron-specific enolase (NSE) and prolactin (PRL). All elevated tumor markers improved dramatically after the removal of the tumor. Immunohistochemically examined, the tumor was stained positive for PLAP and NSE and negative for PRL. Our present case is the first report of dysgerminoma showing positive immunostaining for PLAP and NSE, and the association of high serum level of PRL followed by decrease accompanied by the tumor debulking.

Adult↗
PubMed1998

Effects of interaural decorrelation on neural and behavioral detection of spatial cues.

The detection of interaural time differences (ITDs) for sound localization critically depends on the similarity between the left and right ear signals (interaural correlation). We show that, like humans, owls can localize phantom sound sources well until the correlation declines to a very low value, below which their performance rapidly deteriorates. Decreasing interaural correlation also causes the response of the owl's tectal auditory neurons to decline nonlinearly, with a rapid drop followed by a more gradual reduction. A detection-theoretic analysis of the statistical properties of neuronal responses could account for the variance of behavioral responses as interaural correlation is decreased. Finally, cross-correlation analysis suggests that low interaural correlations cause misalignment of cross-correlation peaks across different frequencies, contributing heavily to the nonlinear decline in neural and ultimately behavioral performance.

Animals↗
PubMed1998

Multiple endocrine neoplasia 2B with glaucoma associated with codon 918 mutation of the RET proto-oncogene.

PURPOSE: We report the first case of a 35-year-old Japanese man with multiple endocrine neoplasia (MEN) 2B de novo to be associated with primary open angle glaucoma. METHODS: DNA was extracted from the patient's circulating leukocytes, specimens of the resected cervical lymph nodes, the neuroma of the eyelid, and of the conjunctival epithelium. Mutation was assayed by PCR/restriction enzyme and direct sequencing. RESULTS: The glaucoma and MEN 2B were diagnosed at the same time, when the patient was 16 years old. The glaucoma was controlled by medical treatment. The codon 918 mutation (met918thr) in exon 16 of the RET proto-oncogene associated with MEN 2B was identified in all these tissues. CONCLUSION: This patient was found to have the germline mutation at codon 918 (met918thr) in the RET proto-oncogene. The association between the RET proto-oncogene and glaucoma remains unclear, since glaucoma is a rare manifestation of MEN 2B.

Adult↗
PubMed1998

Gating of auditory responses in the vocal control system of awake songbirds.

Nucleus HVc of the avian song system is a forebrain structure critical in song production, perception and learning. Here we show that most HVc neurons that respond to auditory stimuli under anesthesia show no responses to the same stimulus in the awake, unrestrained bird. This suppression of auditory responses in awake birds does not occur in the forebrain field L complex, which is one of the auditory input stages for HVc. Gating of auditory input at the junction between the auditory and vocal control system may be essential for regulating auditory feedback signals necessary for song learning and maintenance.

Animals↗
PubMed1998

Steady state relation between cytoplasmic free Ca2+ concentration and force in intact frog skeletal muscle fibers.

The steady state relation between cytoplasmic Ca2+ concentration ([Ca2+]i) and force was studied in intact skeletal muscle fibers of frogs. Intact twitch fibers were injected with the dextran-conjugated Ca2+ indicator, fura dextran, and the fluorescence signals of fura dextran were converted to [Ca2+]i using calibration parameters previously estimated in permeabilized muscle fibers (Konishi and Watanabe. 1995. J. Gen. Physiol. 106:1123-1150). In the first series of experiments, [Ca2+]i and isometric force were simultaneously measured during high K+ depolarization. Slow changes in [Ca2+]i and force induced by 15-30 mM K+ appeared to be in equilibrium, as instantaneous [Ca2+]i versus force plot tracked the common path in the rising and relaxation phases of K+ contractures. In the second series of experiments, 2,5-di-tert-butylhydroquinone (TBQ), an inhibitor of the sarcoplasmic reticulum Ca2+ pump, was used to decrease the rate of decline of [Ca2+]i after tetanic stimulation. The decay time courses of both [Ca2+]i and force were dose-dependently slowed by TBQ up to 5 micro M; the instantaneous [Ca2+]i- force relations were nearly identical at >/=1 micro M TBQ, suggesting that the change in [Ca2+]i was slow enough to reach equilibrium with force. The [Ca2+]i-force data obtained from the two types of experiments were consistent with the Hill curve using a Hill coefficient of 3.2-3.9 and [Ca2+]i for half activation (Ca50) of 1.5-1.7 micro M. However, if fura dextran reacts with Ca2+ with a 2.5-fold greater Kd as previously estimated from the kinetic fitting (Konishi and Watanabe. 1995. J. Gen. Physiol. 106:1123-1150), Ca50 would be 3.7-4.2 micro M. We also studied the [Ca2+]-force relation in skinned fibers under similar experimental conditions. The average Hill coefficient and Ca50 were estimated to be 3.3 and 1.8 microM, respectively. Although uncertainties remain about the precise levels of [Ca2+]i, we conclude that the steady state force is a 3rd to 4th power function of [Ca2+]i, and Ca50 is in the low micromolar range in intact frog muscle fibers, which is in reasonable agreement with results obtained from skinned fibers.

Animals↗
PubMed1998

Hereditary nonpolyposis colorectal cancer associated with duodenal carcinoma: a case report.

Hereditary nonpolyposis colorectal cancer is an autosomal, dominantly inherited disease, characterized by an early age of onset, right colon predominance and an association with various extracolorectal malignancies. We present a case of a 47-year-old woman who met the clinical criteria for the diagnosis of hereditary nonpolyposis colorectal cancer from her past and family histories. She had undergone operations for uterine cancer (histology not confirmed) at age 35 and for advanced cancer of the ascending colon at age 45. Gastroendoscopy revealed a flat elevated lesion, 20 mm in size, with a protrusion (type IIa + Is) in the second portion of the duodenum in March 1996. Additionally, colonoscopy showed a flat elevated lesion, 30 mm in size, with an irregular and nodular surface (type IIa, laterally spreading tumor) in the descending colon. After the operation, the resected specimen of the duodenum histologically showed a well-differentiated adenocarcinoma associated with a tubulo-villous adenoma which had invaded the submucosal layer. The tumor of the colon was histologically confirmed to be a moderately-differentiated adenocarcinoma with submucosal invasion. A high frequency of replication error positivity (4/5 loci) was detected in both of the tumors. Reports of early cancer of the duodenum, associated with extracolorectal malignancies in hereditary nonpolyposis colorectal cancer, are very rare in the literature. Although it is difficult to determine which extracolorectal tumor sites should be taken into consideration by screening programs, we believe that careful observation by upper gastrointestinal endoscopy, which includes the duodenum, is necessary for patients with hereditary nonpolyposis colorectal cancer.

Colonoscopy↗
PubMed1998

Effects of balanced vasodilator, flosequinan, on aortic impedance in failing heart.

An arteriovenous vasodilator, flosequinan, has been shown to be effective for the treatment of acute heart failure. However, little is known as to its effect on aortic impedance, which is known to be a proper and precise expression of left ventricular (LV) afterload. To evaluate the acute cardiovascular effect of flosequinan in failing heart, we administered flosequinan intravenously to seven dogs with cardiac failure produced by an infusion of carbon powder (20-50 microm in diameter) into left main trunks of coronary artery. The LV-pump function was severely impaired after intracoronary injection of carbon powder, as evidenced by the findings that cardiac output, circumferential shortening velocity (mean Vcf), and peak +dP/dt of LV pressure were all decreased, associated with a significant increase in LV end-diastolic pressure. Flosequinan (0.9 mg/kg, i.v.) increased cardiac output by 28%, mean Vcf by 44%, and peak +dP/dt by 24%, whereas it decreased total systemic resistance by 32%, time constant of LV pressure decay by 22%, and LV end-diastolic pressure by 18%. Moreover, flosequinan substantially decreased the pulsatile components of LV afterload (i.e., characteristic impedance by 11% and arterial wave reflection coefficient by 45%). Thus flosequinan exerted not only positive inotropic but also positive lusitropic effects, in association with a significant reduction of both pulsatile and steady components of LV afterload, contributing to an improvement of LV-pump function in acute cardiac failure.

Animals↗