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Biomedical subjects

H Kato

Publications and source records attributed to H Kato.

At least 505 records · Page 28Linked to original sources
PubMed1999

Surgical considerations regarding cochlear implantation in the congenitally malformed cochlea.

A 4-year-old girl with congenital profound deafness underwent cochlear implant surgery. Preoperative CT and MRI revealed that her inner ears had common-cavity or aplasia-type malformation. The bilateral internal auditory meatus were markedly narrowed. Audiometric examination demonstrated that only slight residual hearing remained in the low-frequency range and that a hearing aid would be of no benefit. Cochlear implantation was performed in her left ear. Because of the abnormal position of the facial nerve, the routine facial recess approach could not be performed. A canal-wall-down mastoidectomy was performed, and multichannel cochlear implant electrodes were inserted by careful drilling of the bony wall of the semicircular canal area. All 22 electrodes were completely inserted into the cavity. The patient can perceive sounds and her hearing ability is progressively improving.

Child, Preschool↗
PubMed1999

Surgical repair of acute collateral ligament injuries in digits with the Mitek bone suture anchor.

Eighteen acute grade III collateral ligament injuries were treated by using the Mitek bone suture anchor. Seven were thumb metacarpophalangeal joint injuries, and eleven were finger proximal interphalangeal joint injuries. Seventeen patients were followed more than 12 months after surgery. All patients were able to use the digits in daily living activities within 5 weeks after surgery, and return to their original work or sports activities within 12 weeks. Pain was completely relieved in 15 patients. Loss of joint motion averaged 7 degrees. In all joints the postoperative lateral stress angle was within 10 degrees of that of the contralateral digit.

Adolescent↗
PubMed1999

The effects of wrist distraction on carpal kinematics.

Changes in carpal kinematics under wrist distraction were studied in fresh cadaveric specimens. A magnetic tracking device measured kinematic motions of the scaphoid, lunate, and third metacarpal relative to the fixed radius in 3 planes of passive motion (coronal, sagittal, and "dart throwers") under progressive distraction loads. The change in percent contribution of the radiocarpal and midcarpal joints was calculated. Radiocarpal motion during extension was decreased as increasing traction was applied, but it increased with flexion. Motion of the scaphoid relative to the lunate was smaller in the oblique plane, resulting in less radiocarpal motion than in the sagittal plane. In the coronal plane, traction had little effect on radial deviation, but ulnar angulation of the scaphoid was greater with ulnar deviation of the wrist. These results suggest that different degrees of tension exist in the palmar and dorsal ligaments with the wrist under traction and during different planes of wrist motion. If wrist motion is desired during fixed traction, such as used clinically with external fixation, the dart-throwers motion (wrist extension with radial deviation and wrist flexion with ulnar deviation) appears to have the least impact on radiocarpal motion. If greater radiocarpal motion is desired, however, such as during postoperative mobilization, flexion-extension and radioulnar deviation will create more radiocarpal motion than the dart-thrower's motion.

Biomechanical Phenomena↗
PubMed1999

The effects of prenatal stress on the development of hypothalamic paraventricular neurons in fetal rats.

The present experiments focused on the influence of prenatal stress on the development of neurons of the hypothalamic paraventricular nucleus in the fetal rat, including corticotropin-releasing factor-containing neurons. Prenatal stress was administered by restraining pregnant rats in a small cage for either 30 (30-min stress group) or 240 min (240-min stress group) daily for three days from embryonic day 15 to 17, and the fetal brains were taken on embryonic day 18 for later analysis. Golgi-impregnated neurons of the paraventricular nucleus in the 240-min stress group revealed that the total length of the processes was significantly shorter than in the control (unstressed) and 30-min stress groups. In addition, the 240-min stress group showed an increase in the number of apoptotic cells in the fetal paraventricular nucleus. On the other hand, Golgi-impregnated neurons of the paraventricular nucleus in the 30-min stress group had a greater degree of cell differentiation as manifested by an increase in both the number of branch points and the total length of the processes from the cell body. Furthermore, the fetal paraventricular nucleus in the 30-min stress group showed enhanced corticotropin-releasing factor messenger RNA expression, while the varicosities of corticotropin-releasing factor-containing axons at the median eminence revealed more matured morphology such as shorter intervals between the varicosities. These findings suggest the duration-dependent effects of prenatal stress on the development of fetal hypothalamic paraventricular nucleus neurons, including corticotropin-releasing factor-containing neurons: long-lasting stress causes neurotoxic changes of fetal paraventricular nucleus neurons, whereas short-lasting stress facilitates the development of these fetal brain neurons. These morphological changes induced by prenatal stress may contribute to behavioral changes of the offspring after birth.

Animals↗
PubMed1999

Assessment of global left ventricular function in normal children and in children with dilated cardiomyopathy.

A Doppler index combining systolic and diastolic time intervals (Tei index) has been reported to be useful for assessing global left ventricular (LV) function and predicting clinical outcome in adult patients with LV dysfunction. However, normal values in children and age-related changes in the index have not yet been clarified. The aim of this study was to prospectively determine normal values of the Tei index and the effect of aging on the index in children and to assess the global cardiac function in patients with dilated cardiomyopathy with this index. The subjects included 161 consecutive normal children aged 30 days to 18 years and 5 patients with dilated cardiomyopathy. The Tei index was defined as the sum of the isovolumetric contraction time and the isovolumetric relaxation time divided by the ejection time and was measured from conventional LV outflow and inflow Doppler velocity profiles. The Tei index correlated significantly with the logarithm of age (r = 0.51, P <. 001). The index decreased with aging until 3 years and then did not change after age 3 years. The Tei index in children under age 3 years (0.40 +/- 0.09, n = 80) was significantly higher than that in children ranging in age from 3 to 18 years old (0.33 +/- 0.02, n = 81). The index in patients with dilated cardiomyopathy (0.78 +/- 0. 28) was markedly increased compared with that in normal subjects. Age-related changes in the Tei index may reflect maturational or developmental alterations in the LV properties in infants. The data in this study give basic information for further quantitative assessment of global cardiac function in children with congenital or acquired heart disease.

Adolescent↗
PubMed1999

Alterations of second messenger systems in the rat brain after 6-hydroxydopamine lesions of the medial forebrain bundle.

We studied the sequential changes in second messenger systems in the striatum and substantia nigra (SN) after 6-hydroxydopamine lesions of the medial forebrain bundle in rats. The animals were unilaterally lesioned in the medial forebrain bundle and the brains were analyzed at 1, 2, 4 and 8 weeks postlesion. [3H]Phorbol-12, 13-dibutyrate (PDBu), [3H]forskolin and [3H]rolipram were used to label protein kinase C (PKC), adenylyl cyclase and calcium/calmodulin-independent cyclic-AMP phosphodiesterase, respectively. The degeneration of nigrostriatal pathway produced a significant increase in [3H]PDBu binding in the ventromedial part of the ipsilateral striatum from 2 to 8 weeks postlesion. In the contralateral side, [3H]PDBu binding showed a transient increase in the SN only 4 weeks after lesioning. [3H]Forskolin binding showed a significant increase in the ipsilateral and contralateral striatum from 2 to 4 weeks postlesion. In the ipsilateral SN, a significant increase in [3H]forskolin binding was observed at 4 weeks after lesioning. However, no significant change in [3H]forskolin binding was observed in the contralateral SN during postlesion. On the other hand, [(3)H]rolipram binding showed no conspicuous alteration in the brain during postlesion. These results demonstrate that rats made hemiparkinsonism by unilateral 6-hydroxydopamine injection have a significant increase in [3H]PDBu and [3H]forskolin binding in the striatum and/or SN, whereas no significant change in [3H]rolipram binding is observed in these areas during postlesion. Our findings also suggest that the increase in [3H]forskolin binding is more pronounced than that in [3H]PDBu binding in the brain after unilateral 6-hydroxydopamine injection. Thus, our studies may provide valuable information concerning degeneration of the nigrostriatal pathway such as Parkinson's disease.

Animals↗
PubMed1999

Elimination of CO2 in patients with carbonic anhydrase II deficiency, with studies of respiratory function at rest.

We evaluated the elimination of CO2 in three Japanese adults with carbonic anhydrase II (CA II) deficiency, as compared with that in 10 healthy volunteers. The patients had no signs of respiratory distress. Heart rate, body temperature, ventilation volume, respiratory rate and (a-ET) PCO2 were found to be higher and PaCO2 tended to be higher in the patients than those in the volunteers, while forced vital capacity (FVC), forced expiratory volume in 1s (FEV1), tidal volume, end-tidal PCO2 (PETCO2), pH and HCO3- in arterial blood were lower in the patients. All three patients had non-anion-gap metabolic acidosis, due to renal losses of bicarbonate, but with virtually no compensatory reduction in PaCO2. However, the high VE and PaO2 suggested that respiratory compensation for this metabolic acidosis was occurring, the elimination of CO2 was possibly facilitated by the presence of other carbonic anhydrase isoenzymes in the pulmonary capillaries. Thus, CA II deficiency causes mild to moderate impairments in CO2 elimination.

Adolescent↗
PubMed1999

A patient who was found to be pregnant unexpectedly during hysteromyomectomy.

We present a case of an unexpected pregnancy and an ultimately successful obstetric outcome. The patient underwent abdominal myomectomy under spinal anaesthesia for a uterine leiomyoma with menorrhagia and infertility. Later, she was found to have been in the 7th gestational day at the time of surgery. The blastocyst survived the surgical manipulation and anaesthesia, resulting in a successful pregnancy. The literature on the endocrinological stress response during anaesthesia and surgery suggests that spinal anaesthesia administered in this case was potentially helpful in maintaining progesterone levels and avoiding increased prolactin levels; increased prolactin levels might be deleterious to implantation of the blastocyst.

Journal Article↗
PubMed1999

Biochemical and molecular characteristics of the brain with developing cerebral infarction.

1. We review the biochemical and molecular changes in brain with developing cerebral infarction, based on recent findings in experimental focal cerebral ischemia. 2. Occlusion of a cerebral artery produces focal ischemia with a gradual decline of blood flow, differentiating a severely ischemic core where infarct develops rapidly and an area peripheral to the core where the blood flow reduction is moderate (called penumbra). Neuronal injury in the penumbra is essentially reversible but only for several hours. The penumbra area tolerates a longer duration of ischemia than the core and may be salvageable by pharmacological agents such as glutamate antagonists or prompt reperfusion. 3. Upon reperfusion, brain cells alter their genomic properties so that protein synthesis becomes restricted to a small number of proteins such as stress proteins. Induction of the stress response is considered to be a rescue program to help to mitigate neuronal injury and to endow the cells with resistance to subsequent ischemic stress. The challenge now is to determine how the neuroprotection conferred by prior sublethal ischemia is achieved so that rational strategies can be developed to detect and manipulate gene expression in brain cells vulnerable to ischemia. 4. Expansion of infarction may be caused by an apoptotic mechanism. Investigation of apoptosis may also help in designing novel molecular strategies to prevent ischemic cell death. 5. Ischemia/reperfusion injury is accompanied by inflammatory reactions induced by neutrophils and monocytes/macrophages infiltrated and accumulated in ischemic areas. When the role of the inflammatory/immune systems in ischemic brain injury is revealed, new therapeutic targets and agents will emerge to complement and synergize with pharmacological intervention directed against glutamate and Ca2+ neurotoxicity.

Animals↗
PubMed1999

Increases in [3H]FK-506 and [3H]L-N(G)-nitro-arginine binding in the rat brain after nigrostriatal dopaminergic denervation.

Receptor autoradiographic technique was studied to investigate sequential changes in FK-506 binding proteins, nitric oxide synthase and dopamine uptake sites in the brain 1 week to 8 weeks after unilateral 6-hydroxydopamine injection of the medial forebrain bundle in rats. [3H]FK-506, [3H]L-N(G)-nitro-arginine and [3H]mazindol were used to label FK-506 binding proteins (immunophilin), nitric oxide synthase and dopamine uptake sites, respectively. [3H]FK-506 binding showed about 13-25% increase in the ipsilateral striatum from 2 to 8 weeks after degeneration of nigrostriatal pathway. However, no significant change in [3H]FK-506 binding was observed in the ipsilateral substantia nigra during the postlesion periods. In the contralateral side, [3H]FK-506 binding also showed about 13-25% increase in the striatum from 2 to 8 weeks postlesion. The substantia nigra showed a 21% increase in [3H]FK-506 binding only 2 weeks after the lesioning. On the other hand, [3H]L-N(G)-nitro-arginine binding showed about 21-31% increase in the parietal cortex and striatum 1 week or 2 weeks postlesion. In the contralateral side, a 21% increase in [3H]L-N(G)-nitro-arginine binding was found in the dorsolateral striatum only 1 week postlesion. In contrast, degeneration of nigrostriatal pathway caused a conspicuous loss of [3H]mazindol binding in the ipsilateral striatum (87-96%), substantia nigra (36-73%) and ventral tegmental area (91-100%) during the postlesion periods. In the contralateral side, no significant changes in [3H]mazindol binding were observed in these areas up to 8 weeks after the postlesion. The present study demonstrates that unilateral injection of 6-hydroxydopamine into the medial forebrain bundle of rats can cause a significant increase in [3H]FK-506 and [3H]L-N(G)-nitro-arginine bindings in the brains. In contrast, a marked reduction in [3H]mazindol binding is observed in the brains after the lesioning, indicating severe damage to nigrostriatal dopaminergic pathway. These results suggest that immunophilin and nitric oxide synthase may play some role in the pathogenesis of neurodegenerative disorders such as Parkinson's disease.

Animals↗
PubMed1999

The immunogenicity of various peptide antigens inducing cross-reacting antibodies to a cell surface protein antigen of Streptococcus mutans.

A cell surface protein antigen (PAc) of Streptococcus mutans may be involved in the binding of bacteria to the tooth surface, and has long been focused upon as a candidate for a preventive vaccine of dental caries. Previously the peptide PAc (365-377) was shown to raise an antibody in B10.D2 mice which inhibited the binding of salivary components to the PAc molecule. Using this peptide as a unit peptide, two constructs based on multiple antigenic peptides, and several types of tandem repeats of two or three copies were synthesized to estimate the immunogenicity of these peptides. Increase in the immunogenicity was observed for all constructs with the use of an adjuvant compared to the unit peptide alone. However, the tandem repeat constructs generally induced antibody production in the absence of adjuvant, while the multiple antigenic peptide constructs did not induce antibody production under the same condition. Although such a phenomenon may be restricted to this particular peptide sequence, these results may influence the strategy for the design of peptide vaccines.

Amino Acid Sequence↗
PubMed1999

Primary systemic carnitine deficiency is caused by mutations in a gene encoding sodium ion-dependent carnitine transporter.

Primary systemic carnitine deficiency (SCD; OMIM 212140) is an autosomal recessive disorder characterized by progressive cardiomyopathy, skeletal myopathy, hypoglycaemia and hyperammonaemia. SCD has also been linked to sudden infant death syndrome. Membrane-physiological studies have suggested a defect of the carnitine transport system in the plasma membrane in SCD patients and in the mouse model, juvenile visceral steatosis. Although the responsible loci have been mapped in both human and mouse, the underlying gene has not yet been identified. Recently, we cloned and analysed the function of a novel transporter protein termed OCTN2. Our observation that OCTN2 has the ability to transport carnitine in a sodium-dependent manner prompted us to search for mutations in the gene encoding OCTN2, SLC22A5. Initially, we analysed the mouse gene and found a missense mutation in Slc22a5 in jvs mice. Biochemical analysis revealed that this mutation abrogates carnitine transport. Subsequent analysis of the human gene identified four mutations in three SCD pedigrees. Affected individuals in one family were homozygous for the deletion of a 113-bp region containing the start codon. In the second pedigree, the affected individual was shown to be a compound heterozygote for two mutations that cause a frameshift and a premature stop codon, respectively. In an affected individual belonging to a third family, we found a homozygous splice-site mutation also resulting in a premature stop codon. These mutations provide the first evidence that loss of OCTN2 function causes SCD.

Amino Acid Sequence↗
PubMed1999

Comparison of endoscopic features of early-stage squamous cell lung cancer and histological findings.

Seventy cases with early-stage central-type squamous cell carcinoma were treated surgically between 1984 and 1993 in seven participating institutes. We classified endoscopic features of early-stage central-type squamous cell carcinoma into three types (hypertrophic type, nodular type and polypoid type). After surgery we investigated the relationship between endoscopic features and both the area of superficial extent and depth of carcinoma invasion based on histopathological investigations of the surgical specimens. In 66.7% of the hypertrophic type lesions cancer cells did not invade into the cartilaginous layer, and only 4.8% of this type showed tumour invasion beyond the bronchial cartilage. On the other hand, a few nodular and polypoid type cases showed in-situ carcinoma or carcinoma with invasion from the subepithelial layer to the muscle layer, and in approximately 20% the these types we observed carcinoma invasion beyond the cartilaginous layer, which was not suitable for photodynamic therapy. Also, concerning the greatest dimension 24 out of 35 lesions (68.6%) less than 10 mm in the greatest dimension were evaluated as either in-situ carcinoma or micro-invasive tumour within the muscle layer. The endoscopic features can provide a basis for the determination of therapeutic strategy in early-stage central-type lung cancer.

Aged↗
PubMed1999

New variations of human CC-chemokine receptors CCR3 and CCR4.

CCR3 and CCR4 are the members of CC chemokine receptor family expressed on Th2 type CD4+ T cells. In this study, variation screening of the entire coding regions of CCR3 and CCR4 was performed, and possible association with several autoimmune diseases was tested, using the genomic DNA from 304 Japanese healthy individuals and 272 Japanese patients with rheumatic diseases. One non-synonymous substitution was identified in CCR3 gene, whereas in CCR4 gene, two non-synonymous and two synonymous substitutions were detected. Among the synonymous substitutions, CCR4 1014(C-->T) was observed in 7.2% of the healthy individuals and 6.6% of the patients, and was considered as a single nucleotide polymorphism. All other variations were observed in only one or two individuals. No significant association was observed between any of the variations and any of the rheumatic diseases. Among these variations, CCR3-C218S substitution coded by 652(T-->A) substitution was localized in the region conserved among the G protein coupled receptor family. Reactivity of eosinophils to the monoclonal antibody against CCR3 and the chemotaxis to eotaxin were slightly reduced in this patient as compared with healthy controls or a patient with Behçet disease homozygous for the common allele, while CCR3 mRNA level was not different. These findings suggest that CCR3-C218S substitution may lead to the reduced function of CCR3 at the protein level. Further study will be of interest to test whether CCR3-C218S variation or any of the CCR4 variations has a significant role in rendering susceptibility to immunological diseases or resistance to HIV infection.

Alleles↗
PubMed1999

Lumichrome. A larval metamorphosis-inducing substance in the ascidian Hhalocynthia roretzi.

It has long been known that metamorphosis of ascidian larvae is induced by exposure to adult tunic extract or larval-conditioned seawater. However, such a natural 'inducer' has not been identified, probably due to its very low concentration in organisms. Here we have succeeded in isolating the same metamorphosis-inducing substance from the larvae, the larval-conditioned seawater, and the adult tunic of the ascidian Halocynthia roretzi. Structural analysis revealed that this substance was identical to lumichrome. Lumichrome was active toward H. roretzi larvae, but inactive toward another ascidian larvae, suggesting that lumichrome is species-specific. Riboflavin (vitamin B2), from which lumichrome might be derived from, was found to be inactive in induction of larval metamorphosis. In addition, it was demonstrated that lumichrome is localized predominantly in the basal region of the adhesive organ and the posterior part of the larval trunk. Thus, we propose that lumichrome functions as a natural inducer for larval metamorphosis in H. roretzi. This is the first natural metamorphosis-inducing substance to be identified in ascidians.

Animals↗
PubMed1999

Heterotopic sebaceous glands in the esophagus: histopathological and immunohistochemical study of a resected esophagus.

A resected esophagus with numerous heterotopic sebaceous glands was examined in an attempt to determine whether esophageal heterotopic sebaceous glands are the result of a metaplastic process or a congenital anomaly. The present case concerns a 79-year-old Japanese man with numerous esophageal heterotopic sebaceous glands accompanied by superficial esophageal cancer. The resected esophagus possessed numerous heterotopic sebaceous glands, which could be seen clearly as slightly elevated, yellowish lesions. Histological examination of these glands, all of which were located in the lamina propria, revealed lobules of cells that showed characteristic sebaceous differentiation. Bulbous nests of proliferating basal cells showing sebaceous differentiation were occasionally observed in the esophageal epithelium. Of the antibodies against six different keratins used, only anti-keratin 14 labeled both the heterotopic sebaceous glands and the bulbous nests. Acquired metaplastic change of the esophageal epithelium is probably the pathogenetic mechanism involved in these unusual lesions.

Aged↗
PubMed1999

Paraneoplastic vasculitis associated with esophageal carcinoma.

We report a case of esophageal carcinoma associated with paraneoplastic vasculitis. A 69-year-old man suffered from low-grade fever and numbness of the lower limbs for 3 months before esophageal and gastric carcinomas were detected. Concurrent infection or collagen disease was ruled out following clinical and laboratory examinations. In April 1996, the gastric carcinoma was completely removed by endoscopic mucosal resection, but the symptoms remained. Three weeks later esophagectomy was performed for esophageal carcinoma after which time the fever and numbness disappeared. The esophageal carcinoma was a well-differentiated squamous cell carcinoma invading into the submucosal layer. Twenty-two lymph node metastases were found in 68 resected lymph nodes. Latent thyroid cancer was found. Histologically, vasculitis was detected in the esophagus, stomach and serratus anterior muscle. The distribution and degree of vasculitis were most pronounced in the esophagus. The concurrent onset and spontaneous resolution of fever and numbness after the removal of the esophageal carcinoma suggested a paraneoplastic origin. The majority of patients with malignant neoplasm-associated vasculitis had hematologic neoplasms. Cases of esophageal carcinoma associated with paraneoplastic vasculitis are extremely rare.

Aged↗