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Biomedical subjects

M Koga

Publications and source records attributed to M Koga.

At least 127 records · Page 7Linked to original sources
PubMed2000

Roles of renal dopamine and kallikrein-kinin systems in antihypertensive mechanisms of exercise in rats.

We have previously shown that both renal dopamine (DA) and kallikrein-kinin systems are activated by exercise in mild hypertensives. We aimed to confirm the effects of exercise on the renal DA system and the stimulatory effects of DA on the renal kallikrein-kinin system in rats. In experiment 1, 12 male Dahl salt-sensitive (DS) rats given a 4% salt diet were divided into two groups. Rats in the exercise group were forced to run at 8 m/min, 60 min/day, 5 days/week for 4 weeks. Daily urinary volume, urinary excretion of sodium, free DA, and kallikrein activity were measured weekly. Renal aromatic-L-amino-acid decarboxylase (AADC) activities were assayed at the end of the experiment. In experiment 2, 15 male Sprague-Dawley (SD) rats were randomly divided into 3 groups, a DA-5 (5 microg of DA/kg/min), a DA-10 (10 microg of DA/kg/min), and a control group. DA or vehicle was administered subcutaneously with an osmotic pump for 2 weeks. Daily urinary volume, urinary excretion of sodium, aldosterone, DA, and kallikrein activity were measured weekly. Plasma renin activity, aldosterone concentration, and renal kallikrein mRNA levels were determined at the end of the experiment. In experiment 1, urinary excretion of free DA and renal AADC activities in the exercise group were significantly higher than those in the non-exercise group at week 4. In experiment 2, renal kallikrein mRNA levels and urinary volume were significantly increased in the DA-10 group compared to the control group, although there were no differences in urinary kallikrein activities. Plasma aldosterone concentration was significantly decreased in the DA-10 group compared to that in the control group despite a lack of differences in plasma renin activities. In conclusion, exercise increased the urinary excretion of free DA, probably through increased renal AADC activity in DS rats. DA amplified renal kallikrein mRNA levels and decreased plasma aldosterone levels, probably through its suppression of aldosterone in the adrenal glands. Activation of the kallikrein-kinin system might be counteracted by post-transcriptional modification of aldosterone. These results suggest that exercise enhances renal dopamine production by activating renal AADC activity, which in turn stimulates the renal kallikrein-kinin system.

Aldosterone↗
PubMed2000

A boy with normal growth in spite of growth hormone deficiency after resection of a suprasellar teratoma.

We reported a boy with panhypopituitarism after removal of a suprasellar teratoma and pituitary stalk transection at the age of 3 months. His growth was accelerated after 5 years of age without growth hormone (GH) therapy, although he had poor height growth until age 4 under treatment with hydrocortisone, levothyroxine sodium, and desamino-D-arginine vasopressin (DDAVP). Hyperphagia and obesity developed after surgery. Endocrinological examination revealed no GH response to glucagon, low serum levels of insulin-like growth factor (IGF)-1 and IGF binding protein-3 (IGFBP-3). Serum prolactin was normal, but serum insulin was high. Some patients who received an operation for craniopharyngioma were reported to achieve normal growth without GH secretion, but the mechanism is still unknown. High serum levels of prolactin or insulin can be associated with normal IGF in GH deficient patients. This patient had obesity and high serum insulin, which may be related to growth without GH secretion.

Growth↗
PubMed2000

Re-analysis of clinical features of 89 patients with autoimmune hepatitis using the revised scoring system proposed by the International Autoimmune Hepatitis Group.

OBJECTIVE: The diagnostic criteria of autoimmune hepatitis (AIH) were recently modified by the International Autoimmune Hepatitis Group. This study was performed to assess the impact of the revised scoring system on the diagnosis of AIH. PATIENTS AND METHODS: We re-analyzed the clinical features of 89 patients diagnosed as AIH in Nagasaki Prefecture, Japan, using the revised scoring system, and compared the scores and final diagnosis with our previously published results using the original system. RESULTS: Of the 89 patients with AIH, 40 (45%) were classified using the new system as "definite" AIH, 41 (46%) as "probable" AIH, and 8 (9%) patients were categorized as "others". Of these, 37 (42%), 35 (39%), and 4 (4%) patients who were classified as "definite", "probable", and "others" by the original system remained in the same category by the revised system, respectively. However, 3, 4, and 6 patients were re-categorized as "definite" from "probable", "others" from "probable", and "probable" from "definite", respectively. The difference in aggregate scores between the above two systems ranged from -5 to +2. The main contributing factors to the changes in aggregate AIH score were "other autoimmune disease(s)" and "interface hepatitis without lobular involvement and bridging necrosis on liver histology". However, the main contributing factors to the demotions from "definite" to "probable" and form "probable" to "others" were those related to the characteristics of biliary diseases, i.e., antimitochondrial antibody positive, biliary changes in liver histology, and alkaline phosphatase: aspartate aminotransferase ratio between 1.5 and 3.0. Moreover, two patients who had no histological evidence of AIH were both re-categorized as "others" from "probable" AIH. CONCLUSION: Our results indicated that the diagnosis, whether based on the revised or original system, was the same in the majority of AIH patients, but the revised scoring system excluded cases who had features suggestive of biliary diseases from "definite" AIH, and also confirmed that a diagnosis of "definite" AIH should not be made without liver histology.

Adult↗
PubMed2000

Genetic analysis of Japanese patients with persistent hyperinsulinemic hypoglycemia of infancy: nucleotide-binding fold-2 mutation impairs cooperative binding of adenine nucleotides to sulfonylurea receptor 1.

To elucidate the genetic etiology of persistent hyperinsulinemic hypoglycemia of infancy (PHHI) in the Japanese population, we conducted a polymerase chain reaction-single-strand conformation polymorphism analysis of the sulfonylurea receptor 1 (SUR1) and Kir6.2 genes in 17 Japanese PHHI patients, including a pair of siblings from a consanguineous family. We also analyzed the glutamate dehydrogenase gene for the exons encoding an allosteric regulatory domain of the enzyme. In the SUR1 gene, we identified one frameshift (I446fsdelT) and two missense (R1420C, R1436Q) mutations. None of these mutations were found in control Japanese subjects. Siblings homozygous for the R1420C mutation had a mild form, whereas two patients heterozygous for the I446fsdelT and R1436Q mutations, respectively, exhibited a severe form of PHHI. Functional consequences of these mutations on K(ATP) function were evaluated using 86Rb+ efflux studies in COS-7 cells. SUR1-446fsdelT and SUR1-1436Q did not form a functional K(ATP). Western blot analysis after transient expression in COS-7 cells revealed the expression of SUR1-1436Q protein to be markedly reduced, suggesting SUR1-1436Q to be unstable in these cells. K(ATP)(SUR1-1420C) showed reduced responses to metabolic inhibition by oligomycin and 2-deoxyglucose. K(ATP) channels are under complex regulation by intracellular ATP and ADP. ATP both inhibits and activates these channels. The inhibition is probably mediated through direct ATP interaction with a pore-forming subunit Kir6.2, whereas the activation is likely to be through a regulatory subunit SUR1. There is a cooperative regulation of ATP and ADP binding to SUR1, and this cooperativity may be involved in regulating the K(ATP) channel. In SUR1-1420C, high-affinity binding of ATP to the nucleotide-binding fold (NBF)-1 was indistinguishable from that of wild-type SUR1. However, stabilization of ATP binding to NBF-1 by MgATP or MgADP was impaired, suggesting that this defect may account for impaired K(ATP)(SUR1-1420C) function. This is the first direct biochemical evidence that the cooperativity of nucleotide binding to SUR1 is impaired in a SUR1 mutant causing PHHI. No mutations were identified in the Kir6.2 and glutamate dehydrogenase genes. The genetic etiology of PHHI appears to be heterogeneous. SUR1 mutations may account for no more than 20% of PHHI cases in Japanese patients. Mutations of Kir6.2 and glutamate dehydrogenase genes are likely to be even less common.

ATP-Binding Cassette Transporters↗
PubMed2000

Clinical features and response to treatment in Guillain-Barré syndrome associated with antibodies to GM1b ganglioside.

GM1b is a minor ganglioside in human peripheral nerves. Serum anti-GM1b antibodies frequently are present in patients with Guillain-Barré syndrome (GBS). In this collaborative study, we investigated the antecedent infections, clinical features, and response to treatment of GBS patients with anti-GM1b antibodies. Of 132 GBS patients who participated in the Dutch GBS trial that compared the effect of intravenous immunoglobulins and plasma exchange, 25 (19%) patients had anti-GM1b antibodies. IgM antibodies were present in 14, IgG antibodies in 15, and both isotypes in 4 patients. The 25 patients with anti-GM1b antibodies had a clinical pattern distinct from that of the other 107 GBS patients. They more often had an episode of gastrointestinal illness and frequently showed serological evidence of recent infection by Campylobacter jejuni. The anti-GM1b-positive subgroup was marked by more rapidly progressive, more severe, and predominantly distal weakness. Cranial nerve involvement and sensory deficits were less common in the patients with anti-GM1b antibodies. The presence of anti-GM1b antibodies was associated with slower recovery. The clinical manifestations predominantly were associated with anti-GM1b antibodies of the IgG isotype. Fourteen (56%) of the 25 patients with anti-GM1b antibodies also had anti-GM1 antibodies. The group of patients with both antibodies was clinically more homogeneous and had a more rapidly progressive, pure motor neuropathy. The subgroup of anti-GM1b-positive GBS patients responded well to treatment with immunoglobulins but not to plasmapheresis. The distinctive clinical features of the patients with anti-GM1b antibodies show that acute motor neuropathy represents a specific subgroup within GBS and that recognizing these patients may have consequences as to the choice of therapy.

Adolescent↗
PubMed2000

Ejaculated spermatozoa in patients with non-mosaic Klinefelter's syndrome.

BACKGROUND: Non-mosaic Klinefelter patients are generally azoospermic and there is no therapy to improve the spermatogenesis. Some patients have a few spermatozoa in their ejaculates, which can be used for intracytoplasmic sperm injection (ICSI), but only a few cases resulting in a successful birth have been reported. METHODS: Out of 52 non-mosaic 47,XXY Klinefelter patients, four cases having spermatozoa in their ejaculates were retrospectively studied. RESULTS: Intracytoplasmic sperm injection was performed in three cases using their ejaculates and resulted in one chemical abortion and one death in utero (8 weeks). Using testicular sperm, one patient had a healthy baby with a normal karyotype. CONCLUSION: Some non-mosaic Klinefelter patients have ejaculated sperm that can result in a successful birth following ICSI. However, the birth rate is very low compared with the fertilization rate, suggesting increased risk of chromosomal abnormalities.

Adult↗
PubMed2000

[Adenomatoid tumor of the tunica albuginea: a case report].

A case of male adenomatoid tumor of tunica albuginea of the testis is reported. A 45-year-old man referred to our hospital because of intrascrotal mass on the right side. The mass increased in size for eight months. Then we excised the tumor, and spared the right testis. The tumor was arising from the tunica albuginea of the testis with a pedicle. The histological diagnosis was adenomatoid tumor. Adenomatoid tumor is a rare benign tumor. A total of 97 cases of adenomatoid tumor of epididymis have been reported in males, but only 23 cases of adenomatoid tumor of the testis have been reported in Japan. Herein, 24 cases of adenomatoid tumor of testis including our case are discussed and reviewed.

Adenomatoid Tumor↗
PubMed2000

A case report of nonresective staple exclusion of abdominal aortic aneurysm associated with horseshoe kidney.

A 55 year old male with a history of intermittent claudication presented with an abdominal mass, and was diagnosed by abdominal computed tomography (CT) with an abdominal aortic aneurysm accompanying horseshoe kidney. The horseshoe kidney configuration and governing vessels, urinary duct course, and right common iliac arterial stenosis were shown by methods such as angiogram, spiral CT, and intravenous pyelogram before operation. At the operation, the abdomen was opened by a median incision and, using a staple exclusion technique, the abnormal renal artery was reconstructed using 189 mm knitted Y shaped dacron graft replacement and the great saphenous vein. The isthmus was not resected. There were no post operative complications, nor was there any large decrease in renal function. Good results were obtained, and we herein report our results together with a discussion of the literature.

Aortic Aneurysm, Abdominal↗
PubMed2000

[A case report of treatment for tracheal fistula after radical esophagectomy].

We report our experience of the treatment of a 60-year-old man with upper tracheal fistula which developed on the 11th day after radical surgery for esophageal cancer. Primary treatment to close the fistula was unsuccessful, resulting in the involvement of empyema due to infection. Controlled ventilation with T-tube and drainage through a chest tube for 2 months lead to depuration of the thoracic cavity. As a strategy for secondary closure of the fistula, fenestration was performed on the 87th day postoperatively. The patient's overall condition improved thereafter and closure was being considered. However, the patient died on the 116th day postoperatively due to supervenient aspiration pneumonia. Thus, long-term controlled ventilation with a T-tube was beneficial for the treatment of central airway injury.

Esophageal Neoplasms↗
PubMed2000

Strongyloides ratti: chemotactic responses of third-stage larvae to selected serum proteins and albumins.

Experiments were carried out in vitro to investigate whether the sera of several animals as well as albumins and peptides might act as attractants for larvae of Strongyloides ratti. Samples of sera from several mammal species were dialysed and the aliquots were further centrifuged using ultrafiltration cartridges to remove any remaining small molecules. Additional test substances included commercially obtained ovalbumin, rat and bovine serum albumins, polypeptides such as peptone, tryptone and tryptose, amino nitrogens, monosaccharides, and reduced glutathione (triaminopeptide). Larvae were strongly attracted to the dialysed mammalian sera, which mainly consisted of serum albumin and globulins. Ov- and serum albumins, and polypeptides also acted as attractants. On the other hand, reduced glutathione, 16 kinds of amino acids and four kinds of monosaccharides did not attract this nematode.

Animals↗
PubMed2000

[Retrieval and cryopreservation of testicular sperm].

We reviewed 44 cases of non-obstructive azoospermia treated by testicular sperm extraction and intracytoplasmic sperm injection (ICSI) from July, 1997 to September 1999 at our institutes. Testicular sperm were retrieved from 32 patients (72.7%). ICSI was performed on 29 patients and the partners of 15 patients (46.9%) became pregnant. Out of 10 patients with histology of Sertoli-cell-only, we could retrieve sperm from 3 patients (30%). Testicular volume, Johnsen's score count (JSC), and FSH were significant parameters to predict the recovery of testicular sperm from the patients, but if only the patients with JSC less than 8, are analyzed, none of them was significant parameter. Chromosomal abnormality was not a significant parameter. The partner's age, motility of recovered sperm and testicular volume correlated with the fertilization rate. Chromosomal abnormality or the usage of cryopreserved sperm was not a significant parameter to predict fertilization.

Adult↗
PubMed2000

Axonal Guillain-Barré syndrome: relation to anti-ganglioside antibodies and Campylobacter jejuni infection in Japan.

To clarify the relations of the axonal form of Guillain-Barré syndrome (GBS) to anti-ganglioside antibodies and Campylobacter jejuni infection, 86 consecutive Japanese GBS patients were studied. Electrodiagnostic criteria showed acute inflammatory demyelinating polyneuropathy in 36% of the patients and acute motor axonal neuropathy (AMAN) in 38%. Frequent anti-ganglioside antibodies were of the IgG class and against GM1 (40%), GD1a (30%), GalNAc-GD1a (17%), and GD1b (21%). Identified infections were C. jejuni (23%), cytomegalovirus (10%), Mycoplasma pneumoniae (6%), and Epstein-Barr virus (3%). There was a strong association between AMAN and IgG antibodies against GM1, GD1a, GalNAc-GD1a, or GD1b. Almost all the patients with at least one of these antibodies had the AMAN pattern or rapid resolution of conduction slowing/block possibly because of early-reversible changes on the axolemma. C. jejuni infection was frequently associated with AMAN or anti-ganglioside antibodies, but more than half of the patients with AMAN or anti-ganglioside antibodies were C. jejuni-negative. These findings suggest that the three phenomena "axonal dysfunctions (AMAN or early-reversible conduction failure)," "IgG antibodies against GM1, GD1a, GalNAc-GD1a, or GD1b," and "C. jejuni infection" are closely associated but that microorganisms other than C. jejuni frequently trigger an anti-ganglioside response and elicit axonal GBS.

Adolescent↗
PubMed1999

Rapidly progressive, predominantly motor Guillain-Barré syndrome with anti-GalNAc-GD1a antibodies.

OBJECTIVE: To investigate the presence of anti-GalNAc-GD1a antibodies in patients with Guillain-Barré syndrome (GBS) and to determine the relation of anti-ganglioside antibodies with clinical features. BACKGROUND: The GBS is heterogeneous with regard to clinical manifestations, antecedent infections, and the presence and specificity of anti-ganglioside antibodies. Recently, antibodies to minor gangliosides have been identified in serum from GBS patients. METHODS: The authors used ELISA to detect anti-ganglioside antibodies in 132 GBS patients and then correlated results with a database containing information on antecedent infections and clinical parameters. RESULTS: Anti-GalNAc-GD1a antibodies could be detected in 19 (14%) GBS patients. The presence of anti-GalNAc-GD1a antibodies was related to antecedent Campylobacter jejuni infection (p<0.001). GBS patients with anti-GalNAc-GD1a antibodies had a rapidly progressive, more severe, and predominantly distal weakness. Furthermore, they had less sensory loss, paresthesia, and cranial nerve involvement. In most patients, this reactivity was independent of reactivity to GM1. Dividing patients into separate groups based on their reactivity to GalNAc-GD1a and GM1 enabled the authors to delineate more homogeneous subgroups with regard to clinical features. CONCLUSIONS: This study provides further evidence for the hypothesis that antecedent infections and the specificity of subsequent anti-neural antibody responses determine the clinical manifestations in GBS patients.

Adolescent↗
PubMed1999

Disruption of clh-1, a chloride channel gene, results in a wider body of Caenorhabditis elegans.

We cloned the clh-1 gene coding for a putative ClC chloride channel in Caenorhabditis elegans. The gene product exhibited a high degree of homology with human ClC-1 and ClC-2. The clh-1 gene was predominantly expressed in the hypodermis, including seam cells. Null mutations of clh-1 caused a significantly wider body and an abnormal alae structure. High osmolarity in the culture medium restored the normal body width of the clh-1 mutants. These results suggest that the clh-1 gene contributes to maintenance of the body width through regulation of osmolarity.

Amino Acid Sequence↗
PubMed1999

Acute motor axonal neuropathy and acute motor-sensory axonal neuropathy share a common immunological profile.

Griffin and colleagues (Griffin JW, Li CY, Ho TW, Tian M, Gao CY, Xue P, Mishu B, Cornblath DR, Macko C, McKhann GM, Asbury AK. Pathology of motor-sensory axonal Guillain-Barré syndrome. Ann Neurol 1996;39:17-28 [4]) proposed that acute motor axonal neuropathy (AMAN) and acute motor-sensory axonal neuropathy (AMSAN) are part of the spectrum of a single type of immune attack on the axon. In contrast, IgG anti-GM1 antibody is associated closely with AMAN, but whether other IgG anti-ganglioside antibodies are associated with this neuropathy is not clear. We investigated whether IgG anti-ganglioside antibodies can be used as immunological markers to differentiate AMAN from acute inflammatory demyelinating polyneuropathy (AIDP) and whether these autoantibodies are present in AMSAN. The frequencies of anti-GM1, anti-GM1b, and anti-GD1a IgG antibodies in 21 AMAN patients were significantly higher than in 19 AIDP patients. Anti-GM1b and anti-GD1a IgG, as well as anti-GM1 IgG antibodies, therefore are immunological markers for AMAN. The patients with AMSAN had anti-GM1, anti-GM1b, and anti-GD1a IgG antibodies, indicative that AMAN and AMSAN share a common immunological profile.

Adolescent↗
PubMed1999

Structure of a kallikrein-like enzyme and its tissue localization in the dog.

We previously purified a kallikrein-like enzyme from the dog heart and demonstrated that it is not only able to form kinins but can also convert angiotensin (Ang) I to Ang II. The aim of the present study was to clarify the structure and tissue localization of this enzyme. Western blot analysis of various canine tissues was performed with antiserum against the purified dog heart enzyme. The purified enzyme was subjected to a determination of its amino acid composition and a sequence analysis. Western blotting indicated that this enzyme was present in the heart, aorta, kidney, pancreas, lung, liver, spleen, small intestine, and skeletal muscle. The amino acid composition of the enzyme was different from that of dog urinary kallikrein. Amino acid sequence analysis indicated that it is likely to be N-terminally blocked. The present study showed that this kallikrein-like enzyme is different from previously reported kallikrein and is distributed not only in the heart, but also in other tissues such as the aorta, kidney, lung, liver, spleen, small intestine, and skeletal muscle. This enzyme may exert local effects by generating kinins and Ang II.

Amino Acids↗