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Biomedical subjects

K Imaizumi

Publications and source records attributed to K Imaizumi.

At least 19 recordsLinked to original sources
PubMed2000

Computer-assisted facial image identification system using a 3-D physiognomic range finder.

This system consists of a 3-D physiognomic range finder and a computer-assisted facial image superimposition unit. The 3-D range finder is composed of a detector for measuring facial surface and its control computer. The detector has two sinusoidal grating projection devices and two CCD cameras. The computer-assisted facial image superimposition unit consists of a host computer including a proprietary software, a flat surface color display and a color image scanner for inputting 2-D facial images of a criminal. The 3-D facial shape and texture of a suspect is obtained by using the range finder. To make the comparison between the 3-D facial image and the 2-D facial image, the 3-D facial image is first reproduced on a display of the host computer from a MO disk and then the 2-D facial image is taken with the color image scanner and reproduced on the display. The 3-D facial image is exactly adjusted to match the orientation and size of the 2-D facial image under the fine framework mode, and then the fine framework mode of 3-D facial image is converted to the fine texture image. The shape and positional relationships of facial components between the 3-D and 2-D facial images are examined by the fade-out or wipe image mode. The distance between the selected two points and angle among the selected three points on the 3-D and 2-D facial images are automatically measured for the assessment of anthropometrical data between both images. For evaluating the fit between the anthropometrical points on the 3-D and 2-D facial images, the reciprocal point-to-point difference between both images is compared.

Anthropometry↗
PubMed2000

Lymphatic lipid transport is not impaired in ageing rat intestine.

Lymphatic lipid transport in the intestine of adult and ageing rats was compared. Adult (8-10 months old) and old (24-26 months old) male Wistar rats were cannulated into the mesenteric lymph under ethrane anesthesia. On the following day, lipid emulsion containing 35.4 mg/h of olive oil was infused intraduodenally for 7 h and lymph collected hourly was assayed for triglyceride and apolipoprotein A-IV (apo A-IV). The results showed there was no difference in lymphatic lipid and apo A-IV transport between adult and old rats. Since apo A-IV synthesis in the enterocytes is linked to the intracellular assembly of lipoprotein, it is likely that in addition to lymphatic transport, production of chylomicrons is not impaired in ageing rats.

Aging↗
PubMed2000

Ibotenic acid-induced lesions of the medial septum increase hippocampal membrane associated protein kinase c activity and reduce acetylcholine synthesis: prevention by a phosphatidylcholine/vitamin B12 diet.

Ibotenic acid infusion into the medial septum (MS) results in biochemical alterations in the hippocampus. The biochemical events involved in this neuronal lesion are poorly understood. We investigated the effect of a purified diet supplemented with egg phosphatidylcholine (PC) and vitamin B(12) on ibotenic acid-medicated biochemical changes in the rat hippocampus and crude synaptosomal membranes. Male Wistar rats with this MS lesion were fed a purified diet (control diet) or a purified diet supplemented with 5.7 g PC and 125 microg vitamin B(12) per 100 g (experimental diet) for 18 days. Sham-operated rats were fed the control diet. Compared with the sham-operated rats, MS-lesioned rats fed the control diet showed increased activity of membrane-bound protein kinase C (PKC), decreased activity of choline acetyltransferase, and decreased concentrations of acetylcholine in the hippocampus. The ratio of cholesterol to phospholipid in the crude synaptic membrane was lower in the lesioned rats than in the sham-operated rats, but this was not accompanied by any alteration in membrane lipid fluidity. MS-lesioned rats fed the experimental diet showed lowered PKC activity and elevated acetylcholine concentrations than did rats fed the control diet, but there were no significant effects on choline acetyltransferase activity and the lipid ratio. The ibotenic acid-mediated elevation of PKC activity was observed as early as 2 days postinjury in the control diet-fed rats but not in the experimental diet-fed rats. We propose that ibotenic acid mediates pathophysiologic actions through the activation of PKC and that PC combined with vitamin B(12) ameliorates the second messenger-mediated injury.

Journal Article↗
PubMed2000

Walnuts lower serum cholesterol in Japanese men and women.

Recent studies have shown that incorporating moderate quantities of walnuts into the recommended cholesterol-lowering diet in the U.S. decreased serum concentrations of total cholesterol in normal American men. To explore whether walnut consumption would also prove effective as part of the Japanese diet, we studied the effects of walnut consumption on serum lipids and blood pressure in Japanese subjects. We randomly assigned 20 men and 20 women to two mixed natural diets, each to be consumed for 4 wk in a crossover design. Both diets conformed to the average Japanese diet (reference diet) and contained identical foods and macronutrients, except that 12.5% of the energy of the walnut diet was derived from walnuts (43-57 g/d) (offset by lesser amounts of fatty foods, meat and visible fat). Total cholesterol concentration was 0.16 mmol/L lower for men (P = 0.05) and 0.21 mmol/L lower for women (P<0.01) when they consumed the walnut diet than when they consumed the reference diet. The LDL cholesterol concentrations were 0.18 mmol/L lower for men (P = 0.13) and 0.22 mmol/L lower for women (P<0.01) when they consumed the walnut diet. The ratio of LDL cholesterol to HDL cholesterol and the apolipoprotein B concentration were also lowered by the walnut diet (P<0.05). Blood pressures did not differ between the walnut and reference diet periods. Incorporating moderate quantities of walnuts into the average Japanese diet while maintaining the intake of total dietary fat and energy decreases serum total cholesterol concentrations and favorably modifies the lipoprotein profile in Japanese, particularly in women.

Adult↗
PubMed2000

Frontonasal dysplasia, macroblepharon, eyelid colobomas, ear anomalies, macrostomia, mental retardation, and CNS structural anomalies: another observation.

We report a Japanese girl with brachycephaly, a wide forehead, hypertelorism, macroblepharon with eyelid colobomas, ectropion, a broad nasal root, a depressed nasal tip, macrostomia, a small and grooved chin, ear anomalies, a structural anomaly of the corpus callosum, dilatation of the fourth ventricle, a urogenital sinus, and mental retardation. Cause and inheritance are unknown.

Abnormalities, Multiple↗
PubMed1999

Apple-peel intestinal atresia associated with balanced reciprocal translocation t(2;3)(q31.3;p24.2) mat.

Apple peel intestinal atresia is an apple-peel-appearing bowel obstruction of unknown cause. We describe a Japanese girl with the apple-peel jejunal atresia associated with apparently balanced reciprocal translocation between chromosomes 2 and 3, t(2;3)(q31. 3;p24.2)mat. The translocation breakpoints in the patient may become candidate regions for the putative gene causing apple-peel atresia. Alternatively, the association of the two abnormalities in the patient is coincidental because her phenotypically normal mother had the same chromosome translocation.

Chromosome Banding↗
PubMed1999

Exclusion of linkage of Shwachman-Diamond syndrome to chromosome regions 6q and 12q implicated by a de novo translocation.

Shwachman-Diamond syndrome is a rare genetic disorder of unknown pathogenesis involving exocrine pancreatic insufficiency and hematological and skeletal abnormalities. There is broad clinical variability; the extent of heterogeneity is unknown but comparisons within a large cohort of patients show no striking differences between patients of families with single or multiple affected offspring. Segregation analysis of a cohort of 69 families has suggested an autosomal recessive mode of inheritance. A single constitutional de novo chromosome rearrangement was reported in a Japanese patient involving a balanced translocation, t(6;12)(q16.2;q21.2), thereby suggesting possible loci for a genetic defect. Evenly spaced microsatellite markers spanning 26-32 cM intervals from D6S1056 to D6S304 and D12S375 to D12S346 were analyzed for linkage in members of 13 Shwachman-Diamond syndrome families with two or three affected children. Two-point lod scores were calculated for each marker under assumptions of recessive inheritance and complete penetrance. Negative lod scores indicated exclusion of both chromosome regions. Further, affected sibs were discordant for inheritance of chromosomes in most families based on constructed haplotypes. The cytogenetic abnormality is not associated with most cases of Shwachman-Diamond syndrome.

Bone and Bones↗
PubMed1999

Young-Simpson syndrome: further delineation of a distinct syndrome with congenital hypothyroidism, congenital heart defects, facial dysmorphism, and mental retardation.

Young-Simpson syndrome is a rare congenital disorder, characterized by congenital hypothyroidism, congenital heart defects, facial dysmorphism, cryptorchidism in males, hypotonia, mental retardation, and postnatal growth retardation. We describe the cases of a 5-year-old boy and a 7-year-old girl with a similar constellation of symptoms and compared them with previously reported patients.

Brain↗
PubMed1999

IPP isomerase, an enzyme of mevalonate pathway, is preferentially expressed in postnatal cortical neurons and induced after nerve transection.

To understand the molecular mechanisms underlying the developmental processes of the cerebral cortex, we screened genes whose mRNA expression was up-regulated in neonatal in the rat cortex to a greater extent than in adult by differential display and obtained five genes. Among these genes, we focused on pyrophosphate (isopentenyl diphosphate, dimethylallyl diphosphate: IPP) isomerase gene, the product of which is known as an enzyme of the mevalonate pathway. Rat IPP isomerase was recently cloned and the gene expression was shown to be dependent on the activation of the mevalonate pathway. Its expression and roles in the brain, however, have not been investigated hitherto. In the present study, Northern blots and in situ hybridization analysis showed that at embryonic stage weak signals for IPP mRNA were diffusely detected in the CNS, and the signal in the cortex became intense at postnatal day 1 and maximized in almost all neurons of all layers at postnatal day 7 with a subsequent reduction. At 8 weeks, the expression of IPP isomerase mRNA in neurons decreased, while it was detected in the oligodendrocytes in the regions containing abundant nerve fibers. These findings suggested that IPP isomerase contributes to postnatal neuronal maturation and myelination. We also demonstrated that IPP isomerase mRNA is induced after nerve axotomy, which suggests a relationship between neuronal regeneration and IPP isomerase. Taken together, these results suggest that elevation of IPP isomerase mRNA levels in neurons contributes to construction of nerve fibers both during the postnatal period in the cortex and their regeneration.

Animals↗
PubMed1999

The cell death-promoting gene DP5, which interacts with the BCL2 family, is induced during neuronal apoptosis following exposure to amyloid beta protein.

DP5, which contains a BH3 domain, was cloned as a neuronal apoptosis-inducing gene. To confirm that DP5 interacts with members of the Bcl-2 family, 293T cells were transiently co-transfected with DP5 and Bcl-xl cDNA constructs, and immunoprecipitation was carried out. The 30-kDa Bcl-xl was co-immunoprecipitated with Myc-tagged DP5, suggesting that DP5 physically interacts with Bcl-xl in mammalian cells. Previously, we reported that DP5 is induced during neuronal apoptosis in cultured sympathetic neurons. Here, we analyzed DP5 gene expression and the specific interaction of DP5 with Bcl-xl during neuronal death induced by amyloid-beta protein (A beta). DP5 mRNA was induced 6 h after treatment with A beta in cultured rat cortical neurons. The protein encoded by DP5 mRNA showed a specific interaction with Bcl-xl. Induction of DP5 gene expression was blocked by nifedipine, an inhibitor of L-type voltage-dependent calcium channels, and dantrolene, an inhibitor of calcium release from the endoplasmic reticulum. These results suggested that the induction of DP5 mRNA occurs downstream of the increase in cytosolic calcium concentration caused by A beta. Moreover, DP5 specifically interacts with Bcl-xl during neuronal apoptosis following exposure to A beta, and its binding could impair the survival-promoting activities of Bcl-xl. Thus, the induction of DP5 mRNA and the interaction of DP5 and Bcl-xl could play significant roles in neuronal degeneration following exposure to A beta.

Alzheimer Disease↗
PubMed1999

Neural coding of sound frequency by cricket auditory receptors.

Crickets provide a useful model to study neural processing of sound frequency. Sound frequency is one parameter that crickets use to discriminate between conspecific signals and sounds made by predators, yet little is known about how frequency is represented at the level of auditory receptors. In this paper, we study the physiological properties of auditory receptor fibers (ARFs) by making single-unit recordings in the cricket Teleogryllus oceanicus. Characteristic frequencies (CFs) of ARFs are distributed discontinuously throughout the range of frequencies that we investigated (2-40 kHz) and appear to be clustered around three frequency ranges (</=5.5, 10-12, and >/=18 kHz). A striking characteristic of cricket ARFs is the occurrence of additional sensitivity peaks at frequencies other than CFs. These additional sensitivity peaks allow crickets to detect sound over a wide frequency range, although the CFs of ARFs cover only the frequency bands mentioned above. To the best of our knowledge, this is the first example of the extension of an animal's hearing range through multiple sensitivity peaks of auditory receptors.

Animals↗
PubMed1999

Noonan syndrome and cavernous hemangioma of the brain.

We present two patients with multiple characteristics that occur in Noonan phenotype and cavernous hemangioma of the brain. The first patient, who had been diagnosed radiographically as having a cavernous hemangioma in the left basal ganglia at age 15 years, developed massive intracerebral hemorrhage, resulting in sudden death at home at 19 years. The second patient, who was diagnosed radiographically as having a cavernous hemangioma in the left parietal lobe at age 17 years, is being followed carefully (the patient is currently 18 years old). A review disclosed four cases of structural cerebrovascular abnormalities with or without subsequent hemorrhage. Neither these four patients nor our two patients had any severe anomalies in the heart or large vessels, which are frequently seen in patients with Noonan syndrome. Cerebrovascular abnormalities might have a significant influence on the prognosis of patients with Noonan syndrome, especially those having no severe abnormalities in the heart or large vessels.

Adolescent↗
PubMed1999

Gonadoblastoma, mixed germ cell tumor, and Y chromosomal genotype: molecular analysis in four patients.

This study reports on Y chromosomal genotypes of three patients with gonadoblastoma and one patient with gonadoblastoma and mixed germ cell tumor. Molecular analysis for 35 Y chromosomal loci was performed for DNA samples taken from peripheral leukocytes and lymphoblastoid cell lines, showing that the four patients shared the region between DYS267 at interval 4A and DYF50S1 at interval 6D, with the exception of the region around DYS202 at interval 5K. In the patient with gonadoblastoma and mixed germ cell tumor, Y chromosomal material was preserved in the gonadoblastoma but was lost from the mixed germ cell tumor. The results, in conjunction with previous reports, suggest that GBY (gonadoblastoma locus on the Y chromosome) may be located to a roughly 5-Mb pericentromeric region between DYS267 at interval 4A and DYS270 at interval 5A. The presence of Y chromosomal material in gonadoblastoma is consistent with GBY being involved in the development of gonadoblastoma, and the absence of Y chromosomal material in mixed germ cell tumor would be explained as a consequence of Y chromosomal loss from rapidly proliferating gonadal cancer cells.

Adolescent↗
PubMed1999

A new assay for the analysis of X-chromosome inactivation based on methylation-specific PCR.

The pattern of X-chromosome inactivation in females is currently evaluated by assays of differential methylation in the genes between the active and the inactive X chromosomes, with methylation-sensitive enzymes. We report a new assay in the human androgen receptor (HUMARA) locus involving a methylation-specific polymerase chain reaction (M-PCR) technique, independent of the use of restriction enzymes. The assay involves the chemical modification of DNA with sodium bisulfite and subsequent PCR. By using the assay with specific primers for the methylated allele, we obtained an X-inactivation pattern based on the ratio of the maternal inactive X to the paternal inactive X. These patterns were consistent with those obtained by conventional PCR assay at the same locus in 48 female cases. We also obtained another X-inactivation pattern based on the ratio of the maternal active X to the paternal active X by using specific primers for the unmethylated allele. The latter pattern was complementary to the former pattern, and a combination of these patterns produced a reliable X-inactivation pattern. The assay revealed that 12 (11%) of the 105 normal females had non-random inactivation patterns (>80:20 or <20:80). Four patients with an X; autosome translocation showed extremely non-random patterns, and these results were consistent with those obtained by previous molecular/cytogenetic studies. We conclude that M-PCR provides an accurate assay for X-inactivation and that it can be performed on various DNA samples unsuitable for restriction digestion.

Cell Line, Transformed↗
PubMed1999

Four novel mutations of the Fanconi anemia group A gene (FAA) in Japanese patients.

Fanconi anemia (FA) is an autosomal recessive disorder characterized by pancytopenia, predisposition to cancers, and a diverse variety of congenital malformations. At least eight complementation groups, A through H, have been described. Recently, the FA-A gene (FAA) has been isolated, and a large number of distinct mutations reported in ethnically diverse FA-A patients. Here, we report on the mutation analysis of five FA patients by single-strand conformation polymorphism. Out of five patients, at least three were found to have mutations in the FAA gene. The first patient was a compound heterozygote with a 1-bp deletion and a single-base substitution. The second patient had a heterozygous 2-bp deletion, which introduces a premature termination codon, and the third patient had a heterozygous splice donor site mutation in intron 27.

Base Sequence↗