Short-term starvation increases calcidiol-24-hydroxylase activity and mRNA level in rat kidney

The renal mitochondrial calcidiol-24-hydroxylase activity and the corresponding cytochrome P-450 mRNA level were measured in rats subjected to short-term starvation alone or in combination with calcitriol treatment. Short-term starvation of 24 and 48 h increased the mRNA level by five- and six-fold, respectively. The 24-hydroxylase activity increased by five- and threefold, respectively. Treatment with calcitriol markedly increased the enzyme activity about 20-fold and the mRNA level about six-fold. In rats subjected to calcitriol treatment combined with 24 h of starvation, a significant further increase in enzyme activity was observed. The mRNA levels increased but the difference was not significant statistically. The results indicate that the mechanism by which starvation stimulates the enzymes is different, at least in part, from that behind the stimulatory effect of calcitriol.

Cloning and characterization of a novel natriuretic peptide in frog (Rana catesbeiana)

C-type natriuretic peptide (CNP) is one of three members of the natriuretic peptide family. In the course of cloning frog CNP precursor cDNA, we found cDNA clones encoding a novel natriuretic peptide precursor. This novel natriuretic peptide precursor is a 118-residue peptide, carrying a 22-residue signal peptide at the N terminus and a 17-residue ring structure characteristic of the natriuretic peptide family at the C terminus. The precursor is highly homologous to mammalian CNP precursors. Its C-terminal Cys codon is directly followed by a termination codon. This feature is characteristic of CNP precursor cDNAs. The cGMP-stimulating activity of the novel natriuretic peptide was at the same level with those of frog CNP and mammalian CNPs, when rat CNP receptor was used in the cGMP assay system. Thus, this novel natriuretic peptide is structurally and functionally a member of the C-type natriuretic peptide. We designated the peptide as frog CNP II, and the previously described CNP as frog CNP I. By Northern blot analysis, expression of this novel CNP mRNA was found in brain, heart, lung, and stomach. On the other hand, frog CNP mRNA was mainly expressed in brain, where mammalian CNP mRNA is exclusively expressed. The distribution of the two frog CNPs suggests a complex system for regulating electrolyte and water balance in frog.

Identification of a vitamin D-responsive element in the 5'-flanking region of the rat 25-hydroxyvitamin D3 24-hydroxylase gene

The 5'-flanking region of the rat vitamin D3 24-hydroxylase (P450cc24) gene was examined and a vitamin D-responsive element (VDRE) responsible for the 1 alpha,25-dihydroxyvitamin D3 (1,25-(OH)2D3) enhancement was identified. Unidirectional deletion analyses of the 5'-flanking region indicated that the region [-167/-102] is involved in vitamin D responsiveness. Further functional analyses showed that the segment [-204/-129] conferred the hormone responsiveness in an orientation-independent manner when it was placed upstream to the heterologous thymidine kinase promoter or the rabbit beta-globin promoter. The segment [-204/-129] contained two direct repeat motifs homologous to other VDREs found in the osteocalcin and osteopontin genes. Synthetic oligonucleotides containing the putative VDRE were used for functional analyses and gel mobility shift assays. The proximal [-151/-137], but not the distal [-169/-155] direct repeat activated the transcription in response to 1,25-(OH)2D3 through the beta-globin promoter. Furthermore, the proximal direct repeat formed a complex with the vitamin D receptor and a nuclear accessory factor(s) from COS cells (or retinoid X receptor) in the presence of 1,25-(OH)2D3. These results indicate that a direct repeat motif, AGGTGAgt-gAGGGCG, located at -151 base pairs upstream in the antisense strand binds to a heterologous dimer consisting of the VDR occupied with 1,25-(OH)2D3 and the nuclear accessory factor and that it plays a critical role in mediating the vitamin D enhancement of the rat P450cc24 gene expression.

Regulation of messenger ribonucleic acid expression of 1 alpha,25-dihydroxyvitamin D3-24-hydroxylase in rat osteoblasts

We have reported that PTH inhibits 25-hydroxyvitamin D3-24-hydroxylase messenger RNA (mRNA) expression induced by 1 alpha,25-dihydroxyvitamin D3 [1 alpha, 25-(OH)2D3] in rat kidney but not intestine. In the present study, we examined whether the suppression of 24-hydroxylase mRNA expression by PTH occurs commonly in tissues and cells which have PTH receptors. Administration of 1 alpha, 25-(OH)2D3 into rats fed a synthetic vitamin D-repleted diet containing adequate calcium greatly increased serum levels of calcium and 1 alpha, 25-(OH)2D3. Also, there was a 4-fold increase in bone 24-hydroxylase activity in response to 1 alpha, 25-(OH)2D3 administration. In rats fed a low calcium diet, renal 24-hydroxylase activity was suppressed probably due to secondary hyperparathyroidism. In contrast, the low calcium feeding did not suppress bone 24-hydroxylase activity. The expression of 24-hydroxylase mRNA in rat osteoblastic C-26 and C-11 cells was similar and attained maximal levels 24 h after cells were incubated with 10(-8) M 1 alpha, 25-(OH)2D3. Induction of 24-hydroxylase mRNA expression by 1 alpha, 25-(OH)2D3 was much greater and earlier in immature C-26 cells than mature C-11 cells. Simultaneous addition of PTH, prostaglandin E2, or cAMP together with 1 alpha, 25-(OH)2D3 did not down-regulate mRNA expression of 24-hydroxylase induced by the vitamin in both C-26 and C-11 cells. Of the three osteoblastic cells (C-26, C-20, and C-11) examined, C-26 cells showed the least mRNA expression of vitamin D receptors, in spite of the highest expression of 24-hydroxylase mRNA. These results suggest that unlike in the kidney, bone 24-hydroxylase mRNA expression is not down-regulated by PTH despite of the presence of PTH receptors. They also suggest that the degree of the induction of 24-hydroxylase mRNA by 1 alpha, 25-(OH)2D3 is not explained simply by the vitamin D receptors content.

Felodipine therapy may not alter glucose and lipid metabolism in hypertensives. Felodipine Multicenter Prospective Study Group in Japan

The effects of long-term monotherapy with felodipine, a calcium antagonist, on blood pressure, glucose tolerance, and serum lipid profiles were prospectively investigated in 51 hypertensive patients: 13 with normal glucose tolerance and 38 with glucose intolerance. The levels of plasma glucose, serum lipids, and glycosylated hemoglobin A1c were determined before and during long-term (7.5 +/- 0.5 months; range, 6 to 9 months) therapy with felodipine. A 75-g oral glucose tolerance test was performed before and during long-term felodipine therapy. Significant decreases in both systolic and diastolic blood pressures in both patient groups were maintained during the therapy. Neither fasting nor post-glucose load venous plasma glucose levels were altered in either group of patients, and no patients with normal glucose tolerance developed diabetes mellitus during the study. Serum lipid levels did not change significantly in either group of patients except for significant decreases in high-density lipoprotein cholesterol and apolipoprotein A-I in the group with normal glucose tolerance tests, but those changes remained within the normal range. Furthermore, neither serum lipid nor apolipoprotein levels were altered, even in patients with hypercholesterolemia (total cholesterol levels, > 5.69 mmol/L = 220 mg/dL). These results suggest that long-term therapy with felodipine may not alter glucose and lipid metabolism in hypertensive patients, and felodipine appears to be useful as an antihypertensive agent for hypertensive patients with either dyslipidemia or impaired glucose metabolism.

Expression of mRNA coding for pituitary hormones and pituitary-specific transcription factor in the pituitary gland of the rdw rat with hereditary dwarfism

The rdw rat (gene symbol: rdw) with hereditary dwarfism has been shown immunohistochemically to have subnormal numbers not only of GH- but also of prolactin- and thyrotrophin-positive cells. To characterize the dwarfism of this strain, the expression of pituitary hormone mRNAs was examined by Northern hybridization. The pituitary gland in the rdw rat expressed 30-100 times less GH and prolactin mRNAs than normal controls, whereas mRNAs for pro-opiomelanocortin and the alpha subunit of rat glycoprotein hormone revealed a significant increase. There was a non-significant difference in rat LH-beta subunit and FSH-beta subunit between normal and rdw rats. The suppressed expression of a pituitary-specific transcription factor, Pit-1, is considered to cause hereditary dwarfism in mouse strains Snell and Jackson, whose phenotypes resemble those of the rdw rat. In this study, however, no difference in mRNA expression for Pit-1 was found between rdw rats and controls. This work indicates that the rdw rat may not have the same genotype as the phenotypically similar dwarf mice, Snell, Jackson and Ames.

Comparison between insulin-like growth factor-I (IGF-I) and IGF binding protein-3 (IGFBP-3) measurement in the diagnosis of growth hormone deficiency

To analyze the utility of insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein-3 (IGFBP-3) radioimmunoassay in the diagnosis of growth hormone deficiency (GHD) we measured IGF-I and IGFBP-3 in sera from normal children (n = 309), short children (n = 99) and patients with GHD (n = 73). In 80% and 93% of classical GHD (cGHD), IGF-I and IGFBP-3 levels, respectively, were below the age-related cutoff levels (lower limit). In 81% and 88% of normal short children (NS), IGF-I and IGFBP-3 levels, respectively, were above the age-related cutoff levels. Thus, both IGF-I and IGFBP-3 were good parameters for screening GHD. In contrast, in more than half of partial GHD (pGHD), either IGF-I or IGFBP-3 was above the age-related cutoff levels. The poor discrimination between patients with pGHD and NS by using these two parameters may be the result of their relatively similar GH levels, as compared to cGHD, or due to the limitations of GH stimulation tests. In about 80-90% of NS, IGF-I and IGFBP-3 were above the age-related cutoff levels at all ages. A hundred percent of cGHD under 10 years old had IGFBP-3 below the age-related cutoff levels, whereas 79% of cGHD under 10 years old had IGF-I below the age-related cutoff levels. Thus in the younger age groups, IGFBP-3 may be more sensitive than IGF-I. It may be because IGFBP-3 levels are relatively higher than those of IGF-I in younger subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation and characterization of high molecular weight melanogenic inhibitors naturally occurring in melanoma cells

Intrinsic melanogenic inhibitors with high molecular weights have been isolated from Greene's amelanotic hamster melanoma by DEAE ion-exchange and gel filtration chromatographies. The native molecular weights of two partially purified inhibitors have been determined to be 15 kDa (beta-type) and 67 kDa (gamma-type), respectively, using HPLC gel filtration. Both types of inhibitors, despite their inability to directly inhibit isolated tyrosinase, have been shown to markedly inhibit melanin formation in cultured B16 cells. In contrast to the beta-type inhibitor, the gamma-type inhibitor can induce depigmentation in B16 cells without abolishing their internal tyrosinase activity. Further, it has been determined that both inhibitors contain various amounts of unsaturated fatty acids, C15:1, C18:1, C18:2, C18:3, C20:3, and C20:4, which exhibit depigmentary activities on cultured B16 cells. C15:1 is low in the beta-type, but high in the gamma-type whereas C18:3 is high in the beta-type but low in the gamma-type. These results suggest that the differential action of these inhibitors is most likely due to the composition of the unsaturated fatty acids.

Structural characterization of the gene encoding rat 25-hydroxyvitamin D3 24-hydroxylase

The structural gene encoding 25-hydroxyvitamin D3 24-hydroxylase (P-450cc24) was isolated from the rat genomic DNA. It spans approximately 15 kb, is composed of 12 exons, and was demonstrated by Southern blot analysis to be present as a single copy. One major T residue was identified at the cap site, a putative TATA (ATAAATA) box was located at position -30, and a putative CCAAT box was at -58. Four possible vitamin D responsive elements that may be involved in regulation of 24-hydroxylase expression were found in the 5'-flanking region. Alignment with mitochondrial P-450 proteins showed that 7 out of 11 intron insertion sites of P-450cc24 gene occupied positions identical with those in the CYP11 family (P-450scc, P-450(11 beta)). The structure of the gene is discussed in relation to present knowledge about the mechanism of regulation of the 25-hydroxyvitamin D3 24-hydroxylase and calcium homeostasis.

HS-142-1, a novel antagonist for natriuretic peptides, has no effect on the third member of membrane bound guanylate cyclases (GC-C) in T84 cells

HS-142-1, a novel non-peptide antagonist for natriuretic peptides, exerts antagonistic actions almost equally on two similar guanylate cyclase-linked natriuretic peptide receptors (GC-A and GC-B), but has little or no effect on the binding of natriuretic peptides to a membrane protein, the so-called "clearance receptor", which binds all natriuretic peptides. The third mammalian form of membrane bound guanylate cyclases (GC-C) was identified not as a natriuretic peptide receptor, but as a receptor for heat-stable enterotoxins (STa). In this study, we examined effects of HS-142-1 on GC-C (STaR) in T84 cells and showed that HS-142-1 exerts neither agonistic nor antagonistic activity for GC-C, indicating that HS-142-1 is not a common antagonist for a family of membrane bound guanylate cyclase receptors, but a specific antagonist for the guanylate cyclase-linked natriuretic peptide receptors.

Usefulness and limitation of measurement of insulin-like growth factor binding protein-3 (IGFBP-3) for diagnosis of growth hormone deficiency

To analyze the utility of insulin-like growth factor binding protein-3 (IGFBP-3) radioimmunoassay for diagnosis of growth hormone deficiency (GHD) we measured IGFBP-3 in sera from normal children, short children and patients with GHD. The sensitivity (true positive ratio) of IGFBP-3 for complete GHD (cGHD) was 93%, while the specificity (true negative ratio) for normal short children (NS) was 88%. In contrast, the sensitivity of IGFBP-3 for partial GHD (pGHD) was only 43%. The poor discrimination between patients with pGHD and NS may be the result of their relatively similar GH level, as compared to cGHD, or due to the limitations of GH stimulation tests. The specificity of IGFBP-3 for NS was excellent in children of all ages: less than 10 years old (87%) and older than 10 (88%). However, sensitivity for GHD was good for children less than 10 years old (84%) but poor for children older than 10 (64%). IGFBP-3 may be less sensitive for diagnosing GHD in older children because IGFBP-3 levels may also increase during puberty due to mechanisms independent of the GH-IGF-I axis.

[Molecular biology of cytochrome P450 in kidney]

Cytochrome P450-catalyzed monooxygenation system is widespread in nature and many isoforms have been found in almost all the tissues of vertebrates. In the kidney, several isoforms of cytochrome P450 families, CYP1, 2, 3, 4, 24, 27 have been characterized by biological, immunochemical and molecular biological techniques. These cytochrome P450 isoforms are localized in the endoplasmic reticulum or mitochondria of kidney cortex and functional in the monooxygenation of a number of substrates, such as steroids, fatty acids, xenobiotics, and vitamin D. Particularly, hydroxylation of vitamin D at positions of 1 and 24 is known to be one of the most important functions of kidney specific P450 isoforms.

Stable expression of natriuretic peptide receptors: Effects of HS-142-1, a non-peptide ANP antagonist

We established clonal cell lines stably expressing each of two subtypes of membrane bound guanylate cyclases (GC-A and GC-B), which are known as natriuretic peptide receptors. Using these cell lines, we showed that GC-A is an ANP/BNP receptor, whereas GC-B is a specific receptor for CNP. Effects of HS-142-1, a novel non-peptide ANP antagonist, on GC-A and GC-B were examined by using these cells. In cells expressing either GC-A or GC-B, HS-142-1 inhibited cGMP production elicited by ANP or CNP with IC50 values of 1.8 micrograms/ml and 1.5 micrograms/ml, respectively, and also competitively blocked specific binding of the natriuretic peptides with IC50 values of 2.2 micrograms/ml and 3.3 micrograms/ml, respectively. These results indicate that HS-142-1 is a potent antagonist of CNP as well as ANP. We also showed that CNP suppressed the growth of cells expressing GC-B by 22% and that HS-142-1 blocked the antiproliferative action of CNP.

Analysis of the eicosapentaenoic acid (EPA) metabolite delta 17-6-keto-PGF1 alpha in human plasma by GC/SIM using [18O] delta 17-6-keto-PGF1 alpha

A method of the microdetermination of delta 17-6-keto-PGF1 alpha, a hydrolyzed metabolite of PGI3, is described. An authentic delta 17-6-keto-PGF1 alpha (120 mg) was prepared from eicosapentaenoic acid (EPA) incubated with homogenate of bovine aortic intima. [18O]delta 17-6-Keto-PGF1 alpha was synthesized by repeating base-catalyzed hydrolysis of methyl ester derivatives in [18O]water, to obtain an internal standard in gas chromatography/selected ion monitoring (GC/SIM) of delta 17-6-keto-PGF1 alpha. Good linear response over the range of 10 pg-10ng was demonstrated. Chromatographic conditions using a MP-65HT column presented nearly baseline separation of delta 17-6-keto-PGF1 alpha and 6-keto-PGF1 alpha. We were able to detect delta 17-6-keto-PGF1 alpha in the range from 6 to 26 pg/ml of the human plasma. The present method can be applied to the determination of delta 17-6-keto-PGF1 alpha in the human urine and plasma.

Separation and concentration of delta 17-6-keto-PGF1 alpha using monoclonal antibody to omega 3-olefin structure of trienoic prostanoids

A monoclonal antibody against cis-3-hexen-1-ol was prepared and used to separate and/or concentrate delta 17-6-keto-prostaglandin F1 alpha (PGF1 alpha) in the human sera. cis-3-Hexen-1-ol was conjugated with the human serum albumin (HSA) according to the N-succinimidylester method and hyperimmunized to BALB/c mouse. The monoclonal antibodies were obtained from hybridoma clones established by a fusion between SP2/0-Ag14-k13 mouse myeloma cells and splenocytes of a mouse. A monoclonal antibody, named 4G9-12B, recognized the epitope characteristic for omega 3-olefin structure. The 4G9-12B antibody became more specific for delta 17-6-keto-PGF1 alpha than 6-keto-PGF1 alpha by applying inhibition ELISA using amino-residue coating plates. Using the prepared immunoaffinity columns of this antibody, delta 17-6-keto-PGF1 alpha was clearly detected in 6 pg/ml of the human blood sera by GC/MS analysis. These results suggest that the monoclonal antibody to the partial structure of trienoic prostanoid, omega 3-olefin unit, and that its immunoaffinity columns are useful in separating and concentrating delta 17-6-keto-PGF1 alpha in the human blood or urine.

Parathyroid hormone inhibits 25-hydroxyvitamin D3-24-hydroxylase mRNA expression stimulated by 1 alpha,25-dihydroxyvitamin D3 in rat kidney but not in intestine

Using a cDNA probe for rat renal 24-hydroxylase, expression of its mRNA was compared in the rat kidney and intestine. Vitamin D-deficient rats received a single injection of 1 alpha,25-dihydroxyvitamin D3. Expression of 24-hydroxylase mRNA was first detected in the kidney at 3-h post-injection and increased thereafter. Similarly, 24-hydroxylase mRNA was expressed in the intestine after 1 alpha,25-dihydroxyvitamin D3 injection. However, the dose level of 1 alpha,25-dihydroxyvitamin D3 required to induce the intestinal 24-hydroxylase mRNA expression was only 1/100 the amount required to induce renal 24-hydroxylase mRNA. Induction of intestinal 24-hydroxylase mRNA expression by 1 alpha,25-dihydroxyvitamin D3 was far more rapid than that of renal 24-hydroxylase mRNA. Thyroparathyroidectomy shortened the time required to induce expression of renal, but not intestinal, 24-hydroxylase mRNA. Administration of either parathyroid hormone or cAMP to vitamin D-deficient rats greatly reduced the expression of 24-hydroxylase mRNA in the kidney but not in the intestine. When rats were fed a vitamin D-repleted diet containing 0.7% (adequate) or 0.03% (low) calcium for 2 weeks, intestinal expression of 24-hydroxylase mRNA could be induced only in the low calcium group. In contrast, renal mRNA expression was preferentially stimulated in the adequate calcium group. These results clearly demonstrate that the expression of 24-hydroxylase mRNA is down-regulated by parathyroid hormone in the kidney but not in the intestine.

The influence of tetrodotoxin on the toxic effects of aconitine in vivo

Both aconite toxins (aconitine, mesaconitine, and hypaconitine) and a pufferfish toxin (tetrodotoxin, TTX) were detected in the blood of a legal autopsy case. In order to elucidate the in vivo influence of TTX on the toxic effects of aconitine, a mixture of aconitine and TTX was administered to male ICR mice orally or intraperitoneally. The animal experiments revealed that the time of death due to aconitine was significantly delayed in proportion to the dose of TTX compared with the case for aconitine alone, and that the mortality of aconitine was lowered by TTX when the dose ratio of the two toxins was in a particular range. Accordingly, it is thought that the toxic effects of aconitine are attenuated by TTX in vivo.

Purification and characterization of beta-galactoside-binding proteins from Caenorhabditis elegans

Two carbohydrate-binding proteins (subunit molecular masses, 32 and 16 kDa, respectively) were isolated for the first time from a nematode, Caenorhabditis elegans. They were specifically extracted with lactose and adsorbed on asialofetuin-Sepharose in the absence of a metal ion. Although these two proteins were co-eluted from a gel filtration column at a position corresponding to an apparent molecular size of 30 kDa under non-denaturing conditions, they could be separated by reversed-phase chromatography. The 32 kDa protein, the main component, was further characterized. Together with its solubility, saccharide specificity and metal independence, some other structural properties, including its amino acid composition, UV spectrum, and partial amino acid sequence, strongly suggested that the 32 kDa protein is a member of a class of soluble beta-galactoside-binding lectins which had previously been only found in vertebrates.

Cloning and characterization of two froms of C-type natriuretic peptide receptor in rat brain

Two similar membrane bound guanylate cyclases (GC-A and GC-B) are known as natriuretic peptide receptors, but have not been well characterized yet. In this study, we have isolated two forms of GC-B cDNA clones along with GC-A cDNA clones from rat brain. The two forms of rat GC-B differ from each other only by 75bp deletion at 3'-flanking region of the putative transmembrane domain, the shorter form lacking the nucleotide binding site by the deletion. Expression of these cDNAs on mammalian cells revealed that (1) GC-B is a specific receptor for CNP whereas GC-A is stimulated effectively both by ANP and BNP, and (2) the two forms of GC-B possess practically the same high binding affinity for CNP while the shorter form could not induce cGMP production by the binding of CNP. These data indicate that in rat brain is present the non-functional receptor for CNP caused by the short deletion.

Ontogenic Expression of Somatostatin-Messenger RNA in the Intestinal Tract of Neonatal Rats

Ontogenic expression of somatostatin (SRIF) -messenger RNA (mRNA) in the gastrointestinal tract was examined in neonatal rats aged from 1 day preterm to 60 days postpartum in comparison with that in the hypothalamus. SRIF-mRNA in the hypothalamus was already expressed in prenatal rats and its developmental change was relatively small. In contrast, a unique pattern of SRIF-mRNA expression was seen in the different intestinal regions, gastric antrum, duodenum, jejunum and colon. In the duodenum, SRIF-mRNA level was low at birth, markedly increased during the postnatal 3 days and declined to the previous level by day 21. Jejunal SRIF-mRNA was found in neonates but progressively decreased in a similar way to duodenum. On the contrary, gastric SRIF-mRNA level, which was low during early development, rose rapidly to a peak on day 21 and gradually declined to an adult level. In the colon age-related change was not conspicuous, remaining at a low level. These results indicate that (1) expression of SRIF gene in the intestinal tract is regulated by local factor(s) as well as developmental stage, and (2) shift of SRIF-mRNA pattern occurs during weaning from the duodenum-dominant infantile pattern to the gastric-dominant adult pattern.

[A case of ventricular septal defect associated with active infective endocarditis which was successfully treated by triple valve replacement and ventricular septal defect patch closure]

A 47-year-old man was hospitalized in May, 1990, because of breathlessness and continuous fever which appeared about 4 weeks after he had had his periodontic tooth removed in December, 1989. He had been diagnosed as having ventricular septal defect (VSD) at the age of 6 years. When he was hospitalized, he was in a condition of class IV by NYHA classification, with a white blood cell count of 17,300/mm3, an increase in CRP, a red blood cell sedimentation rate of 108 mm/hr, and positive alpha-streptococcus in blood culture. His cardiothoracic ratio was 64% with signs of pulmonary congestion on a chest X-ray film. Echocardiography revealed the presence of VSD and huge vegetations on the tricuspid, mitral and aortic valves. He was considered to have active infective endocarditis (AIE) which had presumably been provoked by VSD and the tooth removal. Penicillin G at a daily dose of 20 million units and gentamicin at a daily dose of 80 mg were intravenously administered to treat the alpha-streptococcus infection for about 4 weeks. Furosemide was used for congestive heart failure. Since, although his cardiac function appeared to have been improved, the signs and symptoms of the infection persisted, triple valve replacement for the tricuspid, mitral and aortic valves and patch closure of the VSD were performed 4 weeks after the hospitalization. The operation revealed inflammatory lesions extending from the endocardium of the right ventricle to the mitral valves through the VSD, and huge vegetations on the tricuspid, mitral and aortic valves. The operation was successful and the inflammatory areas gradually disappeared.(ABSTRACT TRUNCATED AT 250 WORDS)

[A case of recurrent hepatocellular carcinoma after hepatic resection surviving over five years by hepatic arterial infusion of lipiodol-anticancer drug suspension]

A 63-year-old male with four intrahepatic recurrences of surgically resected hepatocellular carcinoma was admitted to our hospital in June 1985. He underwent lateral segmentectomy of the liver in November 1983. Pathologic finding of Edmondson II with liver cirrhosis had been confirmed by the operative specimen. Sizes of four recurrent tumors were assessed by CT as 3.5 x 2.2 cm, 2.6 x 2.2 cm, 2.2 x 2.2 cm and 2.2 x 2.2 cm, respectively. During five years until July 1990, the patient was treated with hepatic arterial infusion of Lipiodol-anticancer drug suspension eight times (total 5-FU 900 mg, ADM 77 mg, MMC 73 mg, and Lipiodol 36 ml) and hepatic arterial chemoembolization of MMC microcapsules one time. In addition, two hepatic arterial infusions of CDDP (total 70 mg) were given and 5-FU (total 10 g) was administered intravenously. Partial response (PR) was obtained for 19 months. Hepatic arterial infusion of Lipiodol-anticancer drug suspension was given only once every 6 months, and he maintained a good quality of life for over four and half years. The man died in July 1990. In general, multiple intrahepatic recurrence of surgical resected hepatocellular carcinoma has a poor prognosis. Therefore it was considered that hepatic arterial infusion of this drug brought about the relatively long survival of more than five years.

Isolation and characterization of a cytochrome P-450 from rat kidney mitochondria that catalyzes the 24-hydroxylation of 25-hydroxyvitamin D3

A cytochrome P-450 that catalyzes the 24-hydroxylation of 25-hydroxyvitamin D3 (P-450cc24: P-450cholecalciferol24) was purified to electrophoretic homogeneity from the kidney mitochondria of female rats treated with vitamin D3 (Ohyama, Y., Hayashi, S., and Okuda, K. (1989) FEBS Lett. 255, 405-408). The molecular weight was 53,000, and its absorption spectrum showed peaks characteristic of cytochrome P-450. The turnover number was 22 min-1 and the specific content was 2.8 nmol/mg protein. The N-terminal amino acid sequence, Arg-Ala-Pro-Lys-Glu-Val-Pro-Leu-, is different from the N-terminal sequence of any other cytochrome P-450s so far reported. Upon reconstitution with the electron-transferring system of the adrenal mitochondria, the enzyme showed a high activity in hydroxylating 25-hydroxyvitamin D3 as well as 1 alpha,25-dihydroxyvitamin D3 at position 24. However, the purified enzyme hydroxylated neither vitamin D3 nor 1 alpha-hydroxyvitamin D3. The enzyme was also inactive toward xenobiotics. The enzyme hydroxylated 25-hydroxyvitamin D3 at position 24 but not at 1 alpha, indicating that the enzyme is distinct from that catalyzing 1 alpha-hydroxylation. The reaction followed Michaelis-Menten kinetics, and the Km value for 25-hydroxyvitamin D3 was 2.8 microM. Both vitamin D3 and 1 alpha-hydroxyvitamin D3 inhibited the 24-hydroxylation of 25-hydroxyvitamin D3 in a competitive, concentration-dependent manner. 25-Hydroxyvitamin D3 24-hydroxylase activity was significantly inhibited by 7,8-benzoflavone, ketoconazole, and CO, whereas it was only slightly inhibited by aminoglutethimide, metyrapone, and SKF-525A. Mouse antibodies raised against the cytochrome P-450 inhibited the reaction about 70% and reacted with the P-450cc24 in immunoblotting but did not react with other kinds of cytochrome P-450 in rat liver microsomes and mitochondria.

[Mechanism of the B-B' step formation in M-mode echocardiography]

This study analyzed the mechanism involved in the B-B' step formation of the mitral valve movement using pulsed Doppler and color Doppler echocardiography. We examined 24 patients with first degree atrioventricular block (AVB), 26 with old myocardial infarction (OMI), and 34 with a DDD-pacemaker (PM) (16 with complete AV block and 18 with sick sinus syndrome). In 19 of 24 AVB patients, the B-B' step was associated with diastolic mitral regurgitation (DMR). There was a significant positive correlation between the magnitude of the PQ interval and the B-B' step duration (r = 0.94, p less than 0.001). Intravenous administration of 1 mg of atropine shortened the B-B' step duration from 0.15 +/- 0.06 (SD) to 0.05 +/- 0.07 sec (p less than 0.001). Although changes in the PQ interval were well correlated with changes in the B-B' step duration, the P-B-B' step, or PC interval, did not change significantly. In 12 of the 26 OMI patients, the B-B' step and DMR were both observed. The QC intervals of these patients were longer than those of OMI patients without the B-B' step (0.088 +/- 0.03 vs. 0.066 +/- 0.021 sec, p less than 0.05). The P-B-B' step interval was shorter in the OMI patients than in the AVB patients (0.190 +/- 0.029 vs 0.232 +/- 0.033 sec, p less than 0.01). In 28 of 34 patients implanted with a DDD-pacemaker, the B-B' step and DMR were induced by prolonging the AV delay.(ABSTRACT TRUNCATED AT 250 WORDS)

Triethylene-tetramine (trien) therapy for Wilson's disease

Triethylene tetramine (trien), in increasing dose from 1.0-2.0 g/day to 2.5-3.0 g/day, was used for 4 Japanese patients with Wilson's disease who were intolerant of D-penicillamine (D-PC). Before the treatment, urinary copper excretion (UCE) was 70-96 micrograms/day. UCE increased to 1,512-2,352 micrograms/day on the day of initial administration, and remained at levels between 350-1,100 micrograms/day, thereafter. During 2 months of trien therapy, neurological deficits regressed in three patients, and only slightly in one patient. No adverse effects were observed. These results and the retrospective survey on 17 patients treated with D-PC confirmed that trien is less potent but a safer copper chelating agent than D-PC. The transient aggravation of neurological deficits seen in two patients during the early stage of the treatment suggested that trien, as D-PC, should be started in small doses and gradually increased.

Multi-functional property of rat liver mitochondrial cytochrome P-450

To solve the problem of whether a common enzyme catalyzes both 5 beta-cholestane-3 alpha,7 alpha,12 alpha-triol 27-hydroxylation and 25-hydroxylation of 1 alpha-hydroxyvitamin D3 (a synthetic compound used therapeutically for vitamin D-deficient diseases) in rat liver mitochondria, enzymological and kinetic studies were performed. A cytochrome P-450 was purified from female rat liver mitochondria based on these catalytic activities and it was found that the two enzyme activities accompanied each other at all purification steps. The 5 beta-cholestane-3 alpha,7 alpha,12 alpha-triol 27-hydroxylation activity of the final preparation had a turnover number of 36 min-1, and the value of the corresponding 1 alpha-hydroxyvitamin D3 25-hydroxylation activity was 1.4 min-1. When the enzyme was partially denatured by heating at different temperatures, both enzyme activities declined in a parallel fashion. Treatment of the enzyme with N-bromosuccinimide decreased both enzyme activities in a similar manner. 5 beta-Cholestane-3 alpha,7 alpha,12 alpha-triol competitively inhibited 25-hydroxylation of 1 alpha-hydroxy-vitamin D3 and vice versa. From these results it was concluded that 5 beta-cholestane-3 alpha,7 alpha,12 alpha-triol 27-hydroxylation and 1 alpha-hydroxyvitamin D3 25-hydroxylation are catalyzed by a common enzyme in rat liver mitochondria.

Novel derivatization and immunoextraction to improve microanalysis of 11-dehydrothromboxane B2 in human urine

A new, highly selective procedure for the determination of 11-dehydrothromboxane B2 (11-dehydro-TXB2) in human urine is described. Following the addition of [19,19,20,20-2H4]11-dehydro-TXB2 as an internal standard, samples were extracted with an affinity column of anti-11-dehydro-TXB2. Conversion of the immunoextracted 11-dehydro-TXB2 into its 1-methyl ester-11-n-propylamide-9,12,15-tris-dimethylisopropylsilyl ether derivative was followed by gas chromatography-selected-ion monitoring. The mass spectrum of the 11-dehydro-TXB2 derivative was dominated by the base peak ion of [M-C3H7]+ at m/z 698, which accounted for more than 10% of the total ion current. A typical result showed that the immunoaffinity purification procedures provided an extremely clean alternative to more conventional methods of chromatographic fractionation, and that interfering substances from the urine matrix were almost entirely eliminated during the microanalysis.

Structure of chicken 16-kDa beta-galactoside-binding lectin. Complete amino acid sequence, cloning of cDNA, and production of recombinant lectin

The complete primary structure of chicken 16-kDa beta-galactoside-binding lectin (C-16) was determined. It was composed of 134 amino acid residues and has an acetylated NH2 terminus. A cDNA was also cloned, but no signal sequence was found in the initiator region. The initiator methionine remained as the NH2 terminus of the mature lectin. Although C-16 is distinct from chicken 14-kDa beta-galactoside-binding lectin (C-14), it proved to be a member of the vertebrate 14-kDa-type lectin family. Comparison of the primary structures between the vertebrate 14-kDa-type lectins suggests that C-14 and C-16 were produced by gene duplication of an ancestral lectin gene at a time close to the divergence of birds and mammals. Northern and Southern blot analysis indicated that these isolectins are encoded by individual genes which are differently regulated during the development of the embryo. A recombinant C-16 lectin was produced in Escherichia coli. The product was indistinguishable from the authentic C-16 lectin except that the NH2 terminus of the former was found to begin with free methionine.

Unique property of liver mitochondrial P450 to catalyze the two physiologically important reactions involved in both cholesterol catabolism and vitamin D activation

The cDNA for vitamin D 25-hydroxylase in rat liver mitochondria was transfected in COS cells in order to confirm our previous postulation that both 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha-triol 27-hydroxylation and vitamin D 25-hydroxylation are catalyzed by a common enzyme. As a result it was found that both enzyme activities could be reconstituted from the solubilized extract of mitochondria of these cells, NADPH, NADPH-adrenodoxin reductase and adrenodoxin, giving unequivocal evidence that the two enzyme activities are catalyzed by a common enzyme.

Effect of chemical carcinogens on cholesterol biosynthetic pathways in the skin of mice

The metabolism of zymosterol and mevalonic acid was studied in vitro using the skin homogenates of 3-methylcholanthrene (3MC), diazacholesterol-treated and untreated mice. In normal mouse skin only lathosterol was a major metabolite and the other metabolites, cholesta-5,7,24-trien-3 beta-ol, desmosterol, cholesterol and 7-dehydrocholesterol were much less abundant. However, in the skin homogenate of mice treated with 3MC lathosterol production was depressed, while the production of cholesta-5,7,24-trien-3 beta-ol and desmosterol was significantly increased, the cholesterol level being normal or a little higher. In contrast, in the skin homogenate of mice administered diazacholesterol the production of both lathosterol and cholesterol was almost completely blocked with the slightly increased production of cholesta-5,7,24-trien-3 beta-ol and desmosterol. The metabolism in vitro of [2-14C]-mevalonic acid was quite similar to that of zymosterol, and no additional product which might possibly have been produced by the Kandutsch-Russell pathway was observed. Two pathways for cholesterol biosynthesis, therefore, may exist in mouse skin; the first is lanosterol----zymosterol----5 alpha-cholesta-7,24-dien-3 beta-ol----lathosterol----7-dehydrocholesterol----cholesterol, and the second by Bloch: lanosterol----zymosterol----5 alpha-cholesta-7,24-dien-3 beta-ol----cholesta-5,7,24-trien-3 beta-ol----desmosterol----cholesterol. When mouse skin is treated with 3-MC the former pathway is virtually blocked and the latter is stimulated, keeping the level of cholesterol in the tissue constant or a little higher than normal, which seems to be a significant change in the early stage of chemical carcinogenesis.

[Atrioventricular delay and diastolic mitral regurgitation in patient with DDD pacemaker implantation, and cardiac function]

We examined the mitral valve motion, the mitral valve flow pattern, and changing atrioventricular (AV) delay in 34 patients with DDD pacemaker implantation, using M-mode echocardiography and pulse Doppler echocardiography. In 28 patients, B-B' step and diastolic mitral regurgitation (DMR) were induced by extending the AV delay. 8 of 12 patients who showed B-B' step and DMR with the AV delay less than or equal to 165 mS had heart failures. In such patients, P-B-B' step (DMR) interval was 174 +/- 31 mS shorter than the other patients (216 +/- 26 mS, p less than 0.001), and Q-C interval was 131 +/- 26 mS longer than the other patients (63 +/- 31 mS, p less than 0.001). The minimal value of the AV delay that induces B-B' step and DMR can be decided under the influence of cardiac functions, and this echocardiographic examination is useful, giving us information about the cardiac function of the patients with DDD-PM. B-B' step is the mitral valve motion that corresponds with the DMR, so we can check the DMR through the B-B' step easily.

[Three cases of Rendu-Osler-Weber disease associated with abnormal tortuous hepatic arteries]

We reported three cases of Rendu-Osler-Weber disease. Sonography demonstrated markedly dilated, tortuous tubular structures surrounding the portal vein. Pulsed Doppler method showed phasic flow from these tubular structures. It was helpful in the diagnosis of such an intrahepatic vascular abnormality.

Feasibility of using [18O2]11-dehydrothromboxane B2 as an internal standard of immunoaffinity purification followed by gas chromatography/selected ion monitoring

[1,1-18O2]11-Dehydrothromboxane B2 (11-dehydro-TXB2) was prepared by repetitive base-catalyzed hydrolysis of the lactone ring of its [1,1,11-18O3]-analogue, and evaluated for its suitability as an internal standard in gas chromatography/selected ion monitoring (GC/SIM) of 11-dehydro-TXB2. Use of the present [18O2]-analogue as an internal standard may make it a suitable candidate for specific immunoaffinity purification followed by GC/SIM.

Purification of 25-hydroxyvitamin D3 24-hydroxylase from rat kidney mitochondria

25-Hydroxyvitamin D3 24-hydroxylase was purified to an electrophoretically homogeneous state (Mr = 53,000) from kidney mitochondria of female rats treated with vitamin D3.

Endogenous beta-galactoside-binding lectin expression is suppressed in retinol-induced mucous metaplasia of chick embryonic epidermis

The fate of endogenous beta-galactoside-binding lectin of chick embryo (14K type) was investigated during the course of skin differentiation. Lectin (14K) was found in keratinized epidermis and was localized mainly in the basal and intermediate cells. However, the protein lectin in the epidermis disappeared when the cultured skin was treated with vitamin A and mucous metaplasia was observed. The synthesis of lectin mRNA was also strongly suppressed by vitamin A in a concentration-dependent manner. On the other hand, in the dermis, in which the lectin was localized in the extracellular matrix, lectin expression was scarcely affected by vitamin A. These results indicated that the lectin was expressed in the keratinized epidermis but that its expression was suppressed in vitamin A-induced mucous-secreting epithelium. The suppression may be a result of a transition of the epidermal regulatory system to one of mucous-secreting epithelium. This is the first finding that 14K lectin expression might be regulated during the course of the epidermal differentiation.

[The clinical application of ultra-low field (0.02 T) MRI for the diagnosis of lung tumors]

Seventy-one patients with lung tumors were studied by thoracic Ultra-low field MRI (L-MRI) and the efficacy of L-MRI is evaluated as compared with the dynamic CT scan. In staging of lung cancer, L-MRI is not useful because of its poor spatial resolution. Both T1 (Inversion recovery) and T2 (long SE) weighted images can differentiate secondary atelectasis from central tumors in 15 out of 18 (78%). This sensitivity is almost equal as that of dynamic CT. IR images with short inversion time (STIR) are particularly useful for their differentiation.

Purification and characterization of 5 beta-cholestane-3 alpha,7 alpha,12 alpha-triol 27-hydroxylase from female rat liver mitochondria

5 beta-Cholestane-3 alpha,7 alpha,12 alpha-triol 27-hydroxylase (5 beta-cholestane-3 alpha,7 alpha,12 alpha-triol, NADPH:oxygen oxidoreductase (26-hydroxylating), EC 1.14.13.15) was purified from female rat liver mitochondria based on its catalytic activity. The final preparation of the enzyme showed a single major band on the sodium dodecyl sulfate-polyacrylamide gel electrophoretogram. The content of purified enzyme was 12 nmol/mg of protein, and the specific activity was 431 nmol/min/mg of protein. The molecular weight of the enzyme was determined from sodium dodecyl sulfate-polyacrylamide gel electrophoresis as 52,500. The absorption spectra of the purified enzyme and that of the dithionite-reduced CO complex showed peaks at 417 and 450 nm, respectively, indicating the enzyme belongs to the cytochrome P-450 family. Upon reconstitution with the electron-transferring system of the adrenal (adrenodoxin and NADPH-adrenodoxin reductase), the enzyme showed high activity hydroxylating 5 beta-cholestane-3 alpha,7 alpha-12-triol at position 27 with a turnover number of 35.5 min-1 and Km of 6.3 microM. The enzyme activity was completely lost when the electron-transferring system was replaced by that of microsomes (NADPH-cytochrome P-450 reductase purified from rat liver microsomes), confirming that the P-450 enzyme was of the mitochondrial type, but not of the microsomal. The omission of cytochrome P-450, adrenodoxin, or NADPH-adrenodoxin reductase resulted in complete loss of enzyme activity. The specific activity toward 5 beta-cholestane-3 alpha, 7 alpha-diol was less than one-half that toward cholestanetriol and that toward cholesterol was about one-fiftieth. The enzyme showed no activity toward xenobiotics such as benzphetamine, 7-ethoxycoumarin, and benzo[a]pyrene. Its activity was not inhibited by metyrapone and slightly inhibited by aminoglutethimide. The enzyme activity was markedly lowered in an atmosphere of CO/O2/N2, 40/20/40.

Purification and characterization of vitamin D 25-hydroxylase from rat liver mitochondria

Vitamin D 25-hydroxylase was purified from female rat liver mitochondria based on the catalytic enzyme activity. The final preparation of cytochrome P-450 was homogeneous judging from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (Mr = 52,500). The specific content of the purified enzyme was 12 nmol/mg of protein. The absorption spectrum of the purified enzyme showed a peak at 417 nm and that of the dithionite-reduced CO complex at 450 nm, indicating the enzyme belongs to the cytochrome P-450 family. Upon reconstitution with the electron-transferring system of the adrenal system (adrenodoxin and NADPH-adrenodoxin reductase), the enzyme showed a high activity in hydroxylating 1 alpha-hydroxycholecalciferol at position 25 with a turnover number of 3.8 min-1 and Km of 54 microM. The enzyme activity was completely lost when the electron-transferring system was repLaced by that of microsomes (NADPH-cytochrome P-450 reductase purified from rat liver microsomes), confirming that the P-450 enzyme was of the mitochondrial type, not the microsomal type. The omission of cytochrome P-450, adrenodoxin, or NADPH-adrenodoxin reductase resulted in complete loss of enzyme activity. The liver mitochondrial cytochrome P-450 hydroxylates vitamin D3 and 1 alpha-hydroxyvitamin D3 at position 25, but did not show any activity toward xenobiotics such as benzphetamine, 7-ethoxycoumarin, and benzo[a]pyrene. The enzyme activity was not inhibited by aminoglutethimide but slightly inhibited by metyrapone. The enzyme activity was markedly inhibited in an atmosphere of CO:O2:N2, 40:20:40.

Isolation and characterization of the chick 14K beta-galactoside-binding lectin gene

Vertebrate endogenous lectins have been implicated in cellular interactions that contribute to embryonic development. We have isolated a cloned segment of the gene for chick 14K type beta-galactoside-binding lectin from a genomic DNA library. Analysis of the structure of the cloned gene as well as the results of genomic Southern blot hybridization revealed that the gene is unique and that the mRNA for the lectin is encoded by four exons separated by three introns. The whole sequence spans 3.1 kilobases in the gene. The first exon encodes only two amino acid residues of the N-terminus of the mature protein and the other three exons encode, respectively, one of the three repeating sequences found in this lectin. These facts strongly support the idea that gene duplications have occurred during the evolution of this lectin. The previous study (Y. Ohyama et al. (1986) Biochem. Biophys. Res. Commun. 134, 51-56) suggested that this lectin is not synthesized as a precursor molecule with a cleavable signal sequence at its amino terminus, although it is known to be secreted into the extracellular matrix. Sequence determination of the upstream region of the mRNA indicated that the ATG located just before the codon for the N-terminal amino acid of the mature protein is the actual translation initiator. Thus it was proved that this lectin is synthesized without an N-terminal cleavable signal sequence, as suggested before.

Alteration of cholesterol biosynthetic pathways in the skin of mice administered polycyclic aromatic hydrocarbons

When polycyclic aromatic hydrocarbons were applied solely or together with a tumor promoter (12-O-tetradecanoylphorbol-13-acetate) to the skin of mice, a marked decrease in the level of lathosterol was observed, reflecting a significant change in the metabolism of sterols. Yet the total amount of cholesterol was not changed. When diazacholesterol (a metabolic inhibitor) was administered to mice, both desmosterol and 5 alpha-cholesta-7,24-dien-3 beta-ol accumulated in the skin, whereas the level of lathosterol decreased. These results seem to suggest that a significant portion of lathosterol is formed via 5 alpha-cholesta-7,24-dien-3 beta-ol in addition to the pathway through methostenol. When polycyclic aromatic hydrocarbon was applied to the skin of the mouse treated with diazacholesterol, a significant increase of desmosterol and a marked drop of the level of 5 alpha-cholesta-7,24-dien-3 beta-ol were observed. These results strongly suggest that polycyclic aromatic hydrocarbons perturb the metabolism of sterol in the skin of mice while keeping the total amount of cholesterol unchanged. A similar metabolism also seems to be operating in tumor tissue itself.

Induction of melanogenesis suppression: cellular pharmacology and mode of differential action

Recent elucidation of regulatory mechanisms of eu- and pheomelanogenesis has led us towards an exciting new era of melanogenesis control. I will chiefly address our progress on inhibitory control of melanogenesis from the macromolecular level to human skin colour. In the past, the exploration and search for skin depigmenting agents has been focussed on and initiated from substances which can suppress isolated tyrosinase in vitro. Now, as I have classified below, many new melanogenic inhibitors have been discovered which, in spite of their non-suppressive effect on isolated naked tyrosinase, suppress melanin formation in the living pigment cell in vitro as well as in the natural world. I will also discuss a recently found unique disorder: unilateral suppression of mixed melanogenesis.

The presence of an aberrant type of human chorionic gonadotropin in patients with gastric or colorectal cancer

Beta subunits of human chorionic gonadotropin (beta-hCG) and human chorionic gonadotropin-like substance (hCGLS) were measured radioimmunologically in the serum and malignant tissue from patients with gastrointestinal cancer. Since serum beta-hCG and hCGLS correlate closely to those in cancer tissues, it is assumed that these two gonadotropins originate from cancer tissues. The serum hCGLS levels in 54 patients with gastrointestinal cancer were significantly higher, when compared with the findings in 19 healthy volunteers and 10 peptic ulcer patients. The frequency of high levels of serum hCGLS accounted for 71 per cent of those with operable gastric cancer, 44 per cent of those with inoperable gastric cancer, 100 per cent of those with operable colorectal cancer, and 67 per cent of those with inoperable colorectal cancer. On the contrary, serum beta-hCG levels did not differ between the volunteers and the cancer patients. In the 17 sera and 15 cancer tissues assayed, beta-hCG did not correlate to hCGLS. Moreover, the high levels of beta-hCG in cancer patients occurred in only 1/14 (7.1 per cent) of the assayed serum, and in 5/14 (35.7 per cent) of the cancer tissue. The increased production of these two hCGs may result from neoplastic transformation of an unrestrained fetal genome responsible for hCG production during gestation. It is assumed that the increased producibility of a defective hCG, i.e., an aberrant hCG such as hCGLS, is characteristic of malignant tumors.

Congenital goiter sustaining normal level of serum triiodothyronine

We attempted to elucidate the deficient site of thyroid hormone biosynthesis in the thyroid gland and the mechanism of sustaining normal T3 level in sera of a patient with congenital goiter. TY, a 8-yr-old boy, first noted the onset of a diffuse goiter at the age of 2. There was no clinical evidence of hypothyroidism except for the slight impairment of intellectual development and the awkward physical activity. BMR, T3-RSU and T4 showed low values (-13%, 20.8% and 2.2 micrograms/dl), but serum T3 was normal (180 ng/dl). Serum TSH was 18 microU/ml. The intrathyroidal T3 and T4 were slightly low. Thyroidal 131I uptake was high, but KSCN discharge test was negative. Percent distribution of 131I labelled amino acids in the pancreatin digested thyroid homogenate was 17.4% in MIT, 33.4% in DIT and 11.3% in T3 and T4. Thyroid iodide peroxidase activities in mitochondrial and microsomal fractions were slightly low (19.6 and 26.8 (normal: 32 +/- 3.0 and 37.4 +/- 9.5) mumoles/mg protein). The activity was not increased by the addition of hematin. Thyroglobulin was found to be normal. A biological half life of 131I labelled T4 was shorter (3.5 days) than that of the normal. Electron microscopic examination exhibited the increment and expansion of endoplasmic reticulum in the follicular cell. Low iodide peroxidase activity of this patient may correlate to low T3 and T4 level in the thyroid cell. Moreover, shortened biological half life of T4 implies that normal T3 level in serum is sustained by the accelerated conversion of T4 to T3 in peripheral tissues.(ABSTRACT TRUNCATED AT 250 WORDS)