Search PubMed⌕ Search

Biomedical subjects

K Ichihara

Publications and source records attributed to K Ichihara.

At least 253 records · Page 14Linked to original sources
PubMed1985

Distribution of patients' test values and applicability of "average of normals" method to quality-control of radioimmunoassays.

Applicability of the Hoffmann's average of normals (Mn) method was evaluated in quality control (QC) of radioimmunoassays (RIA) for thyroxine, 3,5,3'-tri-iodothyronine, thyrotropin, and insulin--assays that are performed routinely in the authors' laboratory. In the first three RIAs, the patterns of the distributions were almost constant and Mn showed significant correlations with values of QC sera and intercepts of the dose-response curve. In insulin RIA, the patterns varied appreciably and Mn showed correlations with parameters that reflect a disturbance in the distribution. Exclusion of assays with abnormal distributions, however, resulted in better correlations of Mn with other QC parameters. These results suggest that average of normals method can be a very useful adjunct to conventional QC methods for RIA. The possibility that the method may be affected by a disturbance in the distribution can be monitored by computation of parameters reflecting such disturbance.

Humans↗
PubMed1985

Multiple forms of cytochrome P-450 in rabbit colon microsomes.

Three cytochrome P-450 preparations, designated as cytochrome P-450ca, cytochrome P-450cb, and cytochrome P-448c fraction, were separated and purified about 23-, 50-, and 29-fold, respectively, from the cholate extracts of rabbit colon mucosa microsomes. Their specific contents were 1.2, 2.6, and 1.5 nmol of cytochrome P-450 per mg of protein, respectively. Cytochrome P-450ca and cytochrome P-450cb migrated as heme-containing polypeptide bands with molecular weights of about 53,000 and 57,000, respectively, on SDS-polyacrylamide gel electrophoresis. The CO-reduced difference spectra of cytochrome P-450ca, cytochrome P-450cb, and cytochrome P-448c fraction showed maxima at 451, 450, and 449 nm, respectively. Cytochrome P-450ca efficiently catalyzed the omega-hydroxylation of prostaglandin A1 (PGA1) and the omega- and (omega-1)-hydroxylation of caprate, laurate, and myristate in the reconstituted system containing cytochrome P-450ca, NADPH-cytochrome P-450 reductase, cytochrome b5, and phosphatidylcholine. In contrast, cytochrome P-450cb and cytochrome P-448c fraction had no detectable activity toward PGA1 and fatty acids. Both catalyzed aminopyrine and benzphetamine N-demethylation. Cytochrome P-448c fraction also hydroxylated benzo(a)pyrene, and phosphatidylinositol or phosphatidylserine exhibited a stimulatory effect on this activity. The results show that rabbit colon microsomes contain catalytically different cytochrome P-450, one of which is specialized for the omega-oxidation prostaglandins, the others being involved in the metabolism of exogenous compounds such as drugs and polycyclic hydrocarbons.

Animals↗
PubMed1985

Recovery of ventricular function in reperfused ischemic rat hearts exposed to fatty acids.

The relationship between tissue levels of fatty acid metabolites in ischemic and reperfused hearts and recovery of mechanical function of these hearts on reperfusion was studied. Isolated rat hearts were exposed to global ischemia for periods up to 60 min under various conditions of coronary flow, O2 supply, and fatty acid concentrations and were then reperfused for either 15 or 30 min under aerobic conditions both with and without fatty acids present. Tissue levels of ATP, creatine phosphate, long-chain acyl CoA, and long-chain acyl carnitine were determined at the end of the ischemic and reperfusion periods. In some experiments K+ arrest during ischemia was used to prevent adenine nucleotide depletion both in the absence and presence of high fatty acids. Although the ability of these hearts to recover their preischemic mechanical function varied from 8 to 90% and tissue levels of acyl CoA and acyl carnitine during ischemia varied from 3- to 10-fold depending on the condition, no correlation was found between the recovery of function during reperfusion and either the presence of fatty acid or high levels of tissue long-chain acyl CoA and carnitine esters during ischemia.

Acyl Coenzyme A↗
PubMed1985

Difference in the time course between increases in coronary flow and in effluent adenosine concentration during anoxia in the perfused rat heart.

The isolated rat heart was perfused by Langendorff's technique with either an oxygenated (95% O2 and 5% CO2) or an anoxic (95% N2 and 5% CO2) solution. Anoxia increased coronary flow and effluent adenosine concentration, but the time course of these changes was discordant; coronary flow increased transiently (the maximum increase in flow was observed within 1-2 min after the onset of anoxia), whereas the effluent adenosine concentration increased as a function of the time during anoxia. The concentration of effluent adenosine reached 3 microM 10 min after anoxia. The tissue (myocardial) adenosine content changed in parallel with the effluent adenosine concentration. An infusion of adenosine increased coronary flow dose-dependently, and the maximum increase was obtained when 0.27 microM of adenosine was infused. Effluent adenosine concentration was 0.05-0.3 microM in both anoxia and adenosine infusion experiments at the time when the maximum increase in coronary flow occurred. An increase in concentrations of adenosine above 0.05-0.03 microM in the effluent was not accompanied by an increase in coronary flow. These results raise a question about the role of adenosine in regulating coronary circulation during anoxic perfusion, though there is a possibility of vasodilatory function of adenosine in early period of anoxic perfusion.

Adenosine↗
PubMed1985

[ACTH dependent Cushing's syndrome with an empty sella turcica: report of three cases with emphasis on diagnostic value of selective venous sampling].

Three cases of ACTH dependent Cushing's syndrome are reported with emphasis on diagnostic value of selective venous sampling. Case 1. A 44-year-old female was admitted to our hospital with clinical diagnosis of Cushing's disease. Endocrinological examination revealed typical data of Cushing's disease. High resolution CT scan showed an empty sella turcica, and a chest film showed multi-cystic lesion in the left lower lung field. In the first trial of selective venous sampling, central to peripheral ACTH ratio (C/P ratio) was high at the superior vena cava. So, an ectopic ACTH producing lung tumor was strongly suspected. Further examinations for lung tumor were performed, and finally showed lung cryptococcosis. Therefore, selective venous sampling was performed again, and pituitary ACTH dependency was diagnosed. An eccentric pituitary microadenoma was successfully removed by transsphenoidal surgery. Case 2. A 54-year-old female was admitted to our hospital with clinical diagnosis of Cushing's disease. In the endocrinological examinations plasma ACTH was not respond to provocation of LVP or CRF. In selective venous sampling, C/P ratios of ACTH were not greater than 2.0 at any sampling site. Further examinations showed lung tumor in the lower lobe of left lung. This tumor was surgically proved to be an ectopic ACTH producing lung carcinoid. Case 3. A 24-year-old female was admitted to our hospital for the purpose of further examination of Cushing's disease. Three years previously exploratory transsphenoidal surgery demonstrated an empty sella without adenoma. She received postoperative radiation therapy with a dose of 5000 rad. Endocrinological examination showed typical data due to Cushing's disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1985

[Clinical evaluation of cefminox in pediatric field].

Fundamental and clinical trials were carried out with cefminox (CMNX, MT-141) in pediatric infections. Results were as follows. The mean serum concentrations of CMNX following intravenous injection of 10, 20 and 40 mg/kg were 73.1, 112.5 and 181.4 micrograms/ml at 15 minutes after injection, respectively. The serum half-life times were 1.37, 1.20 and 1.53 hours, respectively. Average recovery rates in the urine until 6 hours from the start of injection were 91.4, 59.4 and 85.8%, respectively. The antimicrobial activity of CMNX against clinically isolated organisms was measured; CMNX was more active than CMZ and CEZ against H. influenzae. CMNX was equal to or more active than CMZ and CEZ against E. coli. CMNX was administered clinically to 32 pediatric patients with various infections; 19-pneumonia, 5-bronchopneumonia, 3-bronchitis and 5-pyelonephritis. Overall efficacy rate was 93.8%. Slight elevation of S-GOT and S-GPT was observed in 2 patients. No other serious side effect was observed.

Anti-Bacterial Agents↗
PubMed1984

[Corticotropin-releasing factor concentrations in cerebrospinal fluid and its diurnal rhythm in patients with Cushing's disease].

Since Vale et al isolated and sequenced a 41 amino acid peptide with corticotropin-releasing factor (CRF) activity from ovine hypothalami, intensive works have been done about its physiological activity and intracerebral distribution. However, little has been done yet about CRF metabolism in human cerebrospinal fluid (CSF). Using a specific ovine CRF radioimmunoassay (RIA), we measured the levels of CRF in CSF from 16 patients with Cushing's disease (group I), 8 patients with Acromegaly (group II), 5 patients with Prolactinoma (group III) and 10 patients without endocrine abnormalities (group IV). Moreover diurnal changes of CRF in CSF from 2 patients with Acromegaly and 2 patients with Cushing's disease were examined. Dilution curves of CRF in CSF were parallel to that of synthetic ovine CRF standard. The intraassay coefficient of variation was 9.2% and the interassay coefficient of variation 12.6%. The concentrations of CRF in CSF of groups I, II, III and IV were 38.83 +/- 9.02 pg/ml (mean +/- SD), 44.24 +/- 4.71, 47.62 +/- 8.05 and 49.45 +/- 12.86, respectively. Group I was significantly lower than group IV (p less than 0.05). On the other hand, group II or III was not significantly different from group IV. A diurnal rhythm of CRF in CSF was observed in 2 patients with Acromegaly. However, there was almost no change in the 2 patients with Cushing's disease. In considering rich amount of CRF in hypothalamus and CRF-positive fibers surrounding the third ventricle, CRF content in CSF seems to reflect mainly its metabolic activity in hypothalamus.(ABSTRACT TRUNCATED AT 250 WORDS)

Acromegaly↗
PubMed1984

sn-Glycerol-3-phosphate acyltransferase in a particulate fraction from maturing safflower seeds.

The properties of the acyl-CoA:sn-glycerol-3-phosphate O-acyltransferase in a 20,000g particulate fraction from maturing safflower seeds were investigated. The optimum pH of the reaction was 7.2. The apparent Km for glycerophosphate was 0.54 mM. Only monoacylglycerophosphate was accumulated in the particulate fraction under normal conditions. Position 1 of glycerophosphate was exclusively esterified with either palmitoyl-CoA or linoleoyl-CoA as acyl donor, while 2-acylglycerophosphate was the minor product. The specificity and selectivity of the acyltransferase for acyl-CoA were broad and somewhat affected by temperature. The concentration of glycerophosphate did not affect the selectivity. These observations suggested that the fatty acid composition of position 1 of safflower triacylglycerol must primarily depend on the composition of the acyl-CoA pool in the site of synthesis, and that growth temperature and the acyl-CoA selectivity of the glycerophosphate acyltransferase may be rather minor factors regarding regulation of the fatty acid composition of position 1 in triacylglycerol.

Acyl Coenzyme A↗
PubMed1984

Ontogeny of molecular forms of CCK-peptides in rat brain and gut.

COOH-terminal immunoreactive cholecystokinin (iCCK) in methanol and acid extracts of brain and gut in the developing rat between 3 and 28 days after birth and in the adult has been fractionated on Sephadex G50. The single peak observed in methanol extracts of brain has an elution volume identical to that of CCK8. Acid extracts of brain contain only 10% as much iCCK as methanol extracts in a molecular form that appears to be a larger precursor because its elution volume on Sephadex is earlier than that of CCK33 or 39. Methanol extracts of duodenum at all ages contain a molecular form which is larger than CCK12 and about equal in abundance to CCK8. Acid extracts of rat duodenum contain 3 peaks: one elutes in the region of a previously described precursor form, CCK58: another co-elutes with CCK33 or 39; the third peak appears to be lower in molecular weight and is most prominent in the 2 week rat duodenum. Whether the larger iCCK found in methanol extracts or the smaller form found in acid extracts is derived from a common CCK precursor is yet to be determined.

Animals↗
PubMed1984

Fractionation of polyclonal antibody by isoelectric focusing--differences in cross-reactivity and affinity of rabbit clonotype anti-human thyrotropin antibody.

Immunoglobulin G (IgG) fractions prepared from three different batches of rabbit antihuman thyrotropin (hTSH) antisera were fractionated by agarose isoelectric focusing (IEF) in the pH ranges 3 to 10 and 5 to 8. Staining of protein in agarose gel after IEF showed that polyclonal IgG separated into more than 20 protein bands with isoelectric points (pIs) ranging from 6 to 9. The clonotype antibodies to hTSH were recovered from the fractions and subjected to radioimmunoassay for determination of the binding-affinity for hTSH and the cross-reactivity with human chorionic gonadotropin (hCG). The affinity constants of the antibodies recovered ranged from 6.4 X 10(9) M-1 to 3.1 X 10(10) M-1, and the cross-reactivities of the clonotype antibodies differed greatly. A good correlation was observed between the pIs of antibody molecules and their cross-reactivities: antibodies with higher pIs bound hCG more strongly than those with lower pIs. The correlation coefficients between the pIs and cross-reactivities were 0.83, 0.84, and 0.87 in three batches of antibody.

Animals↗
PubMed1984

Hydroxylation of prostaglandin A1 by the microsomes of rabbit intestinal mucosa.

Microsomes from rabbit small intestine mucosa were found to catalyze the hydroxylation of PGA1 in the presence of NADPH. The major product was identified as 20-hydroxy PGA1 by using high performance liquid chromatography and gas chromatography-mass spectrometry, and the minor product was assumed to be 19-hydroxy PGA1. The ratio of the former product to the latter was about 24.1. The specific PGA1 omega-hydroxylase activity of small intestine microsomes was comparable to that of liver microsomes, and was significantly higher than those of microsomes from other tissues such as kidney cortex and lung. Microsomes from rabbit colon mucosa also catalyzed the hydroxylation of PGA1 in the presence of NADPH, with the ratio of omega- to (omega-1)-hydroxy PGA1 formed being 33.0. The PGA1 hydroxylase activities of the microsomes from both small intestine and colon were inhibited markedly by carbon monoxide, indicating the participation of cytochrome P-450. A cytochrome P-450 was solubilized from small intestine microsomes, and purified to a specific content of 10.5 nmol of cytochrome P-450/mg of protein. This cytochrome hydroxylated PGA1 at the omega-position with a turnover rate of 38.2 nmol/min/nmol of cytochrome P-450 in the reconstituted system containing cytochrome P-450, NADPH-cytochrome P-450 reductase, cytochrome b5 and phosphatidylcholine. It is suggested that this cytochrome P-450 is specialized for the omega-hydroxylation of PGA1 in small intestine microsomes.

Animals↗
PubMed1984

Isolation of cytochrome P-450 highly active in prostaglandin omega-hydroxylation from lung microsomes of rabbits treated with progesterone.

Two forms of cytochrome P-450, designated as cytochrome P-450p-1 and cytochrome P-450p-2, were separated and purified to specific contents of 8.2 and 8.9 nmol/mg of protein, respectively, from lung microsomes of rabbits treated with progesterone. Cytochrome P-450p-1 and cytochrome P-450p-2 migrated as single polypeptide bands with molecular weights of 49,000 and 52,000, respectively, on SDS-polyacrylamide gel. Their CO-reduced difference spectral peaks were at 451.5 and 450 nm, respectively. Cytochrome P-450p-1 catalyzed the N-demethylation of benzphetamine, O-demethylation of p-nitroanisole, and O-deethylation of 7-ethoxycoumarin, whereas no activity was observed with cytochrome P-450p-2. On the other hand, cytochrome P-450p-2 catalyzed the omega-hydroxylation of prostaglandin E1 (PGE1), prostaglandin E2 (PGE2), and prostaglandin A1 (PGA1) with turnover rates of 9.0, 7.5, and 5.0 nmol of product/min/nmol of cytochrome P-450, respectively, as well as the omega- and (omega-1)-hydroxylation of palmitate and myristate with turnover rates of 27.7 and 16.4 nmol products/min/nmol of cytochrome P-450, respectively. This cytochrome showed a greater affinity for prostaglandins (PGs) than for fatty acids. These reactions were absolutely dependent on cytochrome P-450p-2 and NADPH-cytochrome P-450 reductase, and stimulated by addition of phosphatidylcholine and cytochrome b5. Cytochrome P-450p-2 is thought to be a new form of cytochrome P-450 induced by progesterone treatment in rabbit lung microsomes.

Animals↗
PubMed1984

Purification and characterization of cytochrome P-450 specific for prostaglandin and fatty acid hydroxylase activities from the microsomes of rabbit small intestinal mucosa.

Earlier studies (Kusunose, E., Kaku, M., Ichihara, K., Yamamoto, S., Yano, I., & Kusunose, M. (1984) J. Biochem. 95, 1733-1739) showed that a form of cytochrome P-450 isolated from microsomes of rabbit small intestinal mucosa had the highest prostaglandin A1 (PGA1) hydroxylase activity so far reported among cytochrome P-450s. The present paper describes the procedure for the purification and further characterization of this cytochrome (designated as cytochrome P-450ia). Cytochrome P-450ia had a monomeric molecular weight of 53,000. The CO-difference spectra of its reduced form showed a maximal absorption at 451 nm, and the absolute spectra of its oxidized form indicated that cytochrome P-450ia was present largely in the low-spin state, and partially in the high-spin state. The cytochrome efficiently catalyzed the hydroxylation of fatty acids as well as prostaglandins in a reconstituted system containing cytochrome P-450, NADPH-cytochrome P-450 reductase, phospholipid, and cytochrome b5. PGA1 was the most efficient substrate, followed by myristate, laurate, palmitate, caprate, and PGE1 or PGE2. Among phospholipids, didecanoyl- and dilauroylphosphatidylcholines had the most stimulatory effect for both activities. 20-Hydroxy PGA1 was identified as the hydroxylation product of PGA1 by gas chromatography-mass spectrometry and mass fragmentography; the possibility of 19-hydroxy PGA1 being the product was excluded. In contrast, both omega- and (omega-1)-hydroxy fatty acids were identified as hydroxylation products of fatty acids. Cytochrome P-450ia had no detectable activity toward aminopyrine, benzphetamine, p-nitroanisole, 7-ethoxycoumarin, benzo(a)pyrene, or hexadecane.

Animals↗
PubMed1984

Is ischemia-induced pH decrease of dog myocardium respiratory or metabolic acidosis?

Ischemia causes myocardial acidosis and elevation of myocardial CO2 tension (PCO2). We performed the present study to examine whether accumulation of hydrogen ion is a cause or result of accumulation of CO2. The myocardial pH and PCO2 were measured simultaneously in the dog heart, and the concentration of HCO-3 [( HCO-3]) was calculated according to the Henderson-Hasselbalch equation. Ischemia was induced by either partial or complete occlusion of the left anterior descending coronary artery (LAD). After LAD occlusion, the myocardial pH decreased with a marked decrease in [HCO-3], indicating that metabolic acidosis occurred. We ascertained in experiments with blood sample in vitro that an addition of lactic acid into blood decreased both [HCO-3] and pH (metabolic acidosis), whereas an addition of CO2 gas into blood increased [HCO-3] and decreased pH (respiratory acidosis). These findings suggest that ischemic acidosis is not respiratory in nature, but metabolic. The myocardial pH decrease due to ischemia, however, cannot be explained by the tissue lactate accumulation alone, because the decrease of [HCO-3] is far greater than the increase of lactic acid during ischemia.

Acidosis↗
PubMed1984

Insulin and epidermal growth factor stimulate glycolysis in quiescent 3T3 fibroblasts with no changes in key glycolytic enzyme activities.

In order to study the effect of insulin and epidermal growth factor (EGF) on glycolysis in quiescent 3T3 fibroblasts and their mechanisms of action, lactic acid produced by cells and activities of key glycolytic enzymes in cell extracts were determined. Insulin increased lactic acid production; the maximal stimulation occurred at the concentrations above 250 ng/ml and the half-maximal dose was 50 ng/ml. This effect of insulin appeared as early as one hour, and lactic acid production in the presence of insulin linearly increased up to 4 h. The 24-h pretreatment with insulin exhibited no significant effect on the production by cells afterward incubated either with or without insulin. Lactic acid production decreased as the concentration of phloridzin increased. However, insulin stimulation of the production still remained in the presence of phloridzin. Parahydroxymercuribenzoate reduced production only by the equivalent of the increase due to insulin. EGF also increased lactic acid production; this effect occurred at 1 ng/ml and was maximal at 100 ng/ml. The activities of hexokinase, phosphofructokinase and pyruvate kinase in quiescent cells were not increased by insulin, and the affinities for substrates of these enzymes remained unaltered. These findings suggest that glucose uptake is a rate-limiting step in glycolysis in quiescent 3T3 fibroblasts and that the stimulatory effect of insulin on glycolysis is mediated by enhanced glucose entry.

Animals↗
PubMed1984

Food constituents as a cause of variation of C-peptide excretion in the urine.

Since C-peptide immunoreactivity (CPR) is excreted at a much higher rate than insulin in the urine, the urinary CPR (U-CPR) level could be a good measure of pancreatic B-cell function. In 10 normal subjects and 17 patients with non insulin-dependent diabetes mellitus (NIDDM), the 24-hour U-CPR level was 49.6 +/- 4.5 (mean +/- SE) micrograms, and 59.1 +/- 7.9 micrograms, respectively. When measured repeatedly during 4-37 consecutive days, the mean levels of coefficient of variation (c.v.) of 24-hour U-CPRs in each individual in normal and diabetic patients were 23.4 +/- 3.2%, and 39.1 +/- 1.2%, respectively. Thus, the daily fluctuation of U-CPR was considerably large not only in NIDDM but also in normal healthy subjects. In order to investigate factors responsible for these U-CPR variations, we analyzed the effect of food constituents on U-CPR excretion in this paper. In 8 healthy subjects 5-hour U-CPR excretions were measured after ingesting 5 kinds of isocaloric 300 kcal test meals, i.e. glucose, starch, protein, fat, and mixed meal which consisted of equal kcal of starch, protein and fat. Five hour U-CPR excretion after glucose, starch and protein meal ingestion was 9.5 +/- 1.3 micrograms, 13.7 +/- 1.9 micrograms, and 7.4 +/- 0.9 micrograms, respectively. Fat meal induced no increase in U-CPR excretion. After the mixed meal ingestion, 5-hour U-CPR was 8.2 +/- 0.6 micrograms, which was approximately the mathematical average for the U-CPR after 3 meals. We conclude that the cause of variations in the U-CPR excretion may be ascribed not only to the ingested total calories, but also to the nutritional components of the diet. Therefore, care must be taken in reading a daily U-CPR measurement in assessing pancreatic B cell function.

Adult↗