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Biomedical subjects

K Iba

Publications and source records attributed to K Iba.

70 records · Page 4Linked to original sources
PubMed1984

Transmembrane orientation of reaction centers in proteoliposomes from Rhodopseudomonas sphaeroides.

The photochemical reaction centers from Rhodopseudomonas sphaeroides were reconstituted with soybean phospholipids into liposomes by the cholate-dialysis method. The transmembrane orientation of the reaction centers in the proteoliposomes and the morphology of the vesicles were investigated. The orientation was determined by the reduction of externally added cytochrome c after its photooxidation by a flash. The structure of the vesicles was examined by electron microscope. Discontinuous sucrose density gradient centrifugation yielded several proteoliposome fractions with different vesicular sizes and reaction-center orientations. The proportion of the reaction centers that exposed their cytochrome c reacting sites to the outside of the vesicles increased from 45 to 85% with an increase of the vesicular size. The proportion also depended on the ionic composition of the dialysis buffer. The optimal ionic environment during the dialysis (100 mM NaCl or 2.5 mM MgSO4) gave a liposome yield of 25-30% with a highly asymmetric orientation (greater than 60%). Entrapping of cytochrome c molecules into the phospholipid vesicles had little effect on the orientation of the reaction centers.

Bacterial Proteins↗
PubMed1984

Abnormal calcium metabolism in hemodialyzed patients with diabetic nephropathy.

Calcium metabolism was studied in hemodialyzed patients with diabetes mellitus nephropathy (HD/DM) and in hemodialyzed nondiabetic patients with chronic glomerulonephritis (HD/non-DM). Incidence of bone changes visible in X-ray films, assessed by changes in the lamina dura and trabecular patterns of mandibulae, was less in HD/DM than in HD/non-DM patients. Serum c-terminal parathyroid hormone was significantly lower in HD/DM than that in HD/non-DM. Serum calcitonin was higher in HD/DM than that in HD/non-DM. The lower level of c-terminal parathyroid hormone would be a reason that bone changes were less in HD/DM than in HD/non-DM patients.

Adolescent↗
PubMed1981

A case report of pseudohypoparathyroidism (Drezner's type I) associated with probable Bartter's syndrome.

A 24-yr-old male patient that suffered from chronic tetany since school age. At the age of 20 tetanic convulsions occurred due to hypocalcemia. His mother also had chronic tetany due to pseudohypoparathyroidism. At the age of 24, hypocalcemia caused by pseudohypoparathyroidism was noted. Hypopotassemia persisted even when the hypocalcemia improved with the administration of 1 alpha-hydroxycholecalciferol and calcium lactate. Other findings were normal blood pressure, high levels of plasma renin activity and serum aldosterone, a fall in blood pressure after angiotensin II antagonist infusion, blunted pressor response to angiotensin II infusion and hyperplasia of the juxtaglomerular cells. These results were compatible with Bartter's syndrome. Plasma prostaglandins E2 and F2 alpha in standing position were suppressed after indomethacin administration. To our knowledge this is thought to be the first report of a case of pseudohypoparathyroidism associated with probable Bartter's syndrome.

Adult↗
PubMed1979

Age-related changes of renal osteodystrophy.

Bone changes in 138 patients under hemodialysis were evaluated by radiological methods. Bone mass as was assessed by clavicular score was reduced in patients with chronic renal failure compared with control subjects, especially in male patients, and showed the gradual decrease with aging in both sexes. The incidence of disappearance of lamina dura and that of vascular calcification increased with aging in chronic renal failure. Although serum PTH did not show much difference among various age groups, serum CT and calcium were significantly elevated in 20--24 years of age group compared with other age groups. The etiology of decrease of bone mass in male subjects was discussed from the standpoint of decreased gonadal activity.

Adolescent↗
PubMed1977

A female case of Kallmann's syndrome.

A case of 20-year-old woman with hypogonadotropic hypogonadism and anosmia is reported, since very few female cases of Kallmann's syndrome have been reported so far in Japan. Three uncles on the father's side had no children. Height was 168 cm, and arm span 165 cm. The olfactory test revealed complete anosmia. Bone age was 13 year. Chromosome was 46 XX and normal karyotype. Basal levels of serum FSH, LH and estrogens (E1, E2 and E3) were low. Serum FSH and LH levels rose slightly only after LH-RH administration, and did not increase in clomiphene test. Plasma estrogens did not increase after daily injection of 150 IU of HMG for 3 successive days. The response of serum GH to arginine infusion was normal, while that to insulin-induced hypoglycemia was poor.

Adult↗
PubMed1976

A female case of Kallmann's syndrome.

A case of 20-year-old woman with hypogonadotropic hypogonadism and anosmia is reported, since very few female cases of Kallmann's syndrome have been reported so far in Japan. Three uncles on the father's side had no children. Height was 168 cm, and arm span 165 cm. The olfactory test revealed complete anosmia. Bone age was 13 year. Chromosome was 46 XX and normal karyotype. Basal levels of serum FSH, LH and estrogens (E1, E2 and E3) were low. Serum FSH and LH levels rose slightly only after LH-RH administration, and did not increase in clomiphene test. Plasma estrogens did not increase after daily injection of 150 IU of HMG for 3 successive days. The response of serum GH to arginine infusion was normal, while that to insulin-induced hypoglycemia was poor.

Adult↗
PubMedDate not supplied

Metabolism of 4-[1-(2-fluoro-4-biphenylyl)ethyl]-2-methylaminothiazole (SM-8849) in rats.

Metabolism of 4-[1-(2-fluoro-4-biphenylyl)ethyl]-2-methylaminothiazole (SM-8849), a novel immunomodulatory agent, in rats was investigated. By co-chromatography with authentic samples, desmethylated (SM-8800) p-hydroxylated (SL-5512) and desmethylated-p-hydroxylated SM-8849 (SL-5515) were detected in the bile. Thermospray mass spectrometry (TSP-MS) analysis of five metabolites isolated from the bile revealed molecular ions of both conjugates (glucuronides and a sulfate) and their aglycones. Aglycone structures were determined by comparison of their product spectra with those of authentic standards. Further analyses of conjugation sites were carried out by 1H-NMR including differential NOE. As a result, the sulfate of SL-5515 (5515-S), the N-glucuronides of SL-5512 and SM-8849 (5512-NG and 8849-NG, respectively), the glucuronide of SL-5512 (5512-G) and the O-glucuronide of 4-hydroxy-3-methoxy-SM-8849 (CatOMe-OG) were identified. In addition, N-methylthiouras was identified in urine by LC/MS/MS.

Adjuvants, Immunologic↗
PubMedDate not supplied

Pharmacokinetics of SM-10888 and its metabolites depending on their physicochemical properties.

To investigate how the physicochemical properties and pharmacokinetics of SM-10888 are altered by metabolic reactions, physicochemical and pharmacokinetic parameters of its phase I and phase II metabolites were determined. The metabolic pathways of SM-10888 in rats include oxidation at the C1 position (via the hydroxylated metabolite M3 to the cyclic ketone M4) and glucuronidation of both SM-10888 and M3 (SMG and M3G). Partition coefficients between n-octanol/pH 7.4 buffer (logP*) were determined to be 2.23 for SM-10888, 1.59 for M3, 2.66 for M4, -1.37 for SMG, and -1.72 for M3G. The phase I metabolite M3 showed lower lipophilicity and serum protein binding at pH 7.4, and larger renal clearance (CLr) than SM-10888. In contrast, the further oxidized metabolite M4 demonstrated higher lipophilicity and protein binding and lower CLr than SM-10888 and M3. Among these nonconjugated forms, only the pKa value of M4 was found to be below 7.4 (6.2 for M4, 8.5 for SM-10888, and 8.0 for M3), indicating that M4 exists in a more lipophilic nonionized form at the physiological pH, whereas SM-10888 and M3 are present as ionized forms. The significant shift in pKa of M4 could be the result of a cooperative effect of the electron withdrawing carbonyl group and resonating structure allowing hydrogen bond formation between CO and NH2 group, and might explain its high lipophilicity and low CLr. Glucuronidation significantly increased hydrophilicity with CLr's in excess of the glomerular filtration rate, suggesting involvement of active transport.

Aminacrine↗