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Biomedical subjects

F Suzuki

Publications and source records attributed to F Suzuki.

At least 415 records · Page 23Linked to original sources
PubMed1988

Pathological changes in the cartilaginous plates in relation to intervertebral disc lesions.

Three hundred sixty-eight intervertebral discs (T11/12-L5/S1) were obtained at autopsy from 61 individuals (36 male, 25 female) ranging from 25 to 85 years of age, and subsequently examined histopathologically as sagittal-sectioned specimens with special reference to the cartilaginous plates. The numbers of cartilaginous foci found in fissured and ruptured regions of the plates were found to increase with age, and were considered to represent a restoration mechanism. Measurement of the cartilaginous plate/intervertebral disc antero-posterior length ratio showed a decrease with age in intervertebral discs from the same spinal level. Therefore, cartilage cell proliferation in the vertebral body rim was found following rupture of the outer layer of the annulus fibrosus and was thought to be one of the causes of spur formation in spondylosis deformans. When the changes in a cartilaginous plate with aging were accompanied by destructive processes of the vertebrae such as osteoporosis or metastatic cancer, an increase in the height of the disc, or ballooning, developed. On the other hand, when degeneration of the intervertebral disc increased and the nucleus pulposus collapsed, the height of the disc decreased. Thus, although the cartilaginous plate exhibits a restoration mechanism, degeneration with age progresses, resulting in various disc lesions.

Adult↗
PubMed1988

Differential effects of 1 alpha,25-dihydroxycholecalciferol and 24R,25-dihydroxycholecalciferol on the proliferation and the differentiated phenotype of rabbit costal chondrocytes in culture.

1 alpha,25-Dihydroxycholecalciferol [1,25-(OH)2D3] stimulated the proliferation and DNA synthesis of rabbit costal growth cartilage cells in the logarithmic growth phase in culture. The stimulatory effects of 1,25-(OH)2D3 were observable at a concentration of 10(-10) M and maximal at a concentration of 10(-8) M. On the other hand, 1,25-(OH)2D3 inhibited their expression of the cartilage phenotype, as judged morphologically, histochemically, and biochemically by a decrease in glycosaminoglycan (GAG) synthesis. The inhibition of GAG synthesis was also dose dependent and observable at a concentration of 10(-10) M. 1,25-(OH)2D3 also stimulated the proliferation of resting cartilage cells and inhibited their GAG synthesis, but its effects on these cells were less than those on growth cartilage cells, suggesting that 1,25-(OH)2D3 acts more specifically on growth cartilage cells than on resting cartilage cells. 1,25-(OH)2D3 had no effect on either DNA synthesis or GAG synthesis of growth cartilage cells in confluent cultures. 24R,25-Dihydroxycholecalciferol [24,25-(OH)2D3] had no effect on proliferation, DNA synthesis, or GAG synthesis of growth cartilage cells in the logarithmic growth phase. However, 24,25-(OH)2D3 had no effect on DNA synthesis of these cells in confluent cultures, but stimulated their expression of the cartilage phenotype. The stimulatory effect was dose dependent and maximal at 10(-7) M. Since chondrocytes express their differentiated phenotype as they become confluent in culture, these results suggest that 1,25-(OH)2D3 stimulates the growth of rapidly proliferating chondrocytes with a poorly differentiated phenotype and suppresses their expression of the cartilage phenotype, while 24,25-(OH)2D3 stimulates expression of the differentiated phenotype of highly differentiated chondrocytes.

24,25-Dihydroxyvitamin D 3↗
PubMed1988

Effects of limited exposure of rabbit chondrocyte cultures to parathyroid hormone and dibutyryl adenosine 3',5'-monophosphate on cartilage-characteristic proteoglycan synthesis.

Treatment of rabbit chondrocyte cultures with PTH or (Bu)2cAMP for 30 h increased by 2- to 3-fold the incorporation of [35S]sulfate and 3H radioactivity with glucosamine as the precursor into large chondroitin sulfate proteoglycans characteristically found in cartilage matrix. However, PTH and (Bu)2cAMP did not increase either [35S]sulfate incorporation into small proteoglycans or the incorporation of 3H radioactivity into hyaluronic acid and other glycosaminoglycans. PTH and (Bu)2cAMP also increased the incorporation of [3H] serine into both proteoglycans and total protein. In all cultures described above, the stimulation of [3H]serine incorporation into proteoglycans exceeded that of [3H]serine incorporation into total protein. These data indicate that PTH and (Bu)2cAMP selectively stimulate cartilage proteoglycan synthesis while they increase total protein synthesis. Since cAMP seems to play a mediatory role in the action of PTH, we elected to examine the effects of a limited exposure of chondrocytes to PTH or (Bu)2cAMP on the synthesis of proteoglycans. Treatment with PTH or (Bu)2cAMP for only the initial 2-7 h did not increase the rates of incorporation of [35S]sulfate, the 3H radioactivity with glucosamine, and [3H]serine into proteoglycans, as measured at 30 h, despite the fact that this treatment brought about a rapid and transient rise in the cAMP level. Furthermore, the application of prostaglandin I2 at concentrations that increased cAMP levels in a similar fashion as did PTH did not affect [35S] sulfate incorporation into proteoglycans. These observations suggest that in addition to the transient rise of cAMP, other biochemical changes are required for elaboration of the effect of PTH on proteoglycan synthesis. Although cAMP analogs mimic some of the effects of PTH in chondrocytes, the nucleotides and PTH appear to stimulate proteoglycan synthesis by different mechanisms.

Animals↗
PubMed1988

Studies of Sl/Sld in equilibrium with +/+ mouse aggregation chimaeras. II. Effect of the steel locus on spermatogenesis.

Mutant mice of Sl/Sld genotype are deficient in melanocytes, erythrocytes, mast cells and germ cells. Deficiency of melanocytes, erythrocytes and mast cells is not attributable to an intrinsic defect in their precursor cells but to a defect in the tissue environment that is necessary for migration, proliferation and/or differentiation. We investigated the mechanism of germ cell deficiency in male Sl/Sld mice by producing aggregation chimaeras from Sl/Sld and +/+ embryos. Chimaeric mice with apparent white stripes were obtained. Two of four such chimaeras were fertile and the phenotypes of resulting progenies showed that some Sl/Sld germ cells had differentiated into functioning sperms in the testis of the chimaeras. In cross sections of the testes of chimaeras, both differentiated and nondifferentiated tubules were observed. However, the proportions of type A spermatogonia to Sertoli cells in both types of tubules were comparable to the values observed in differentiated tubules of normal +/+ mice. We reconstructed the whole length of four tubules from serial sections. Differentiated and nondifferentiated segments alternated in a single tubule. The shortest differentiated segment contained about 180 Sertoli cells and the shortest nondifferentiated segment about 150 Sertoli cells. These results suggest that Sertoli cells of either Sl/Sld or +/+ genotype make discrete patches and that differentiation of type A spermatogonia does not occur in patches of Sl/Sld Sertoli cells.

Animals↗
PubMed1988

Renin gene expression in rat tissues: a new quantitative assay method for rat renin mRNA using synthetic cRNA.

A genomic renin exon 9 fragment was subcloned into vector pSPT18 and used for in vitro transcription to obtain 32P-labeled rat renin cRNA. Using this cRNA, we established quantitative solution hybridization and specific Northern blotting assays for renin mRNA. We were able to detect renin mRNA in the kidney, heart ventricle and atrium, brain, testis, and adrenal gland of male rats in the concentrations of 430 +/- 8.1, 110 +/- 1.9, 43 +/- 0.9, 64 +/- 1.1, 47 +/- 0.9 and 11 +/- 0.2 pg mRNA/mg of total RNA, respectively.

Animals↗
PubMed1988

[Modified operation for early gastric cancer; rationale, technic and results].

During 1964 to 1976, standard operation, which consisted of subtotal or total gastric resection, extended dissection of lymph node and omentobursectomy, was performed for early gastric cancer. The result was satisfactory, i.e., 5 year relative survival rate was 95.2 per cent. But there were very few lymph-node metastases, which localized almost perigastric, no marked infiltration into the esophagus in cases of early cancer in the cardiac region. Macroscopic determination about the margin of the cancer was well compatible with microscopic one. The recurrent cases seemed to be due to hematogenous metastasis. These suggest that an extended lymph-node dissection, omentobursectomy and thoracotomy are not necessary for the early cancer. Proximal gastric resection and pylorus preserving gastric resection were indicated in some cases. In addition, the diagnosis of the early cancer, especially about the depth of invasion into the gastric wall, was accurate except for the early cancers which contained ulcerous lesion. Since 1977 modified operation for the early cancer has been applied. At this operation, lymph-node dissection was limited to perigastric region, omentobursectomy was omitted and the pancreas and spleen preserved. Through this method the operative time and blood unit have been much spared and the 5 year postoperative relative survival rate has improved, i.e., 100 per cent. It is concluded that the modified operation should be performed for the early gastric cancer.

Humans↗
PubMed1988

Reno-submandibular axis controls release of extrarenal inactive renin.

The mechanisms causing the release of plasma inactive renin (PIR) area still unclear. We have investigated the role of the kidney in the release of trypsin-activable PIR from extrarenal sources in the rat, with special reference to the submandibular gland. The activation of PIR was performed by incubation with 20 mg/ml trypsin at 4 degrees C for up to 10 min; the reaction was then terminated by addition of 20 mg/ml of soybean trypsin inhibitor. Bilateral nephrectomy resulted in a gradual, marked, sex-independent increase in PIR concentration, reaching levels 4.5 times higher than basal in 24 h (time 0: 14.8 +/- 1.0 ng/ml per h; 24 h: 66.8 +/- 3.4 ng/ml per h, mean +/- s.d., P less than 0.001). This increase was not altered by the concomitant intravenous infusion of pressor doses of either angiotensin (Ang) II (30 ng/min) or pure mouse submandibular renin (a 20-ng intravenous bolus followed by intravenous infusion at the rate of 50 ng/h) for 4 h, but was completely prevented by prior removal of the submandibular glands, in which no activity of active renin and no inactive renin was detected. These results suggest that the post-nephrectomy increase of PIR is not dependent on feedback mechanisms of the suppressed renin-angiotensin system, but is controlled by the presence of submandibular glands in the rat.

Animals↗
PubMed1988

Intracardiac generation of angiotensin and its physiologic role.

The emerging recognition of the existence and potential biological significance of local tissue renin-angiotensin systems in a number of organs has fostered interest in a possible intrinsic cardiac renin-angiotensin system. Evidence for such a system was first provided by biochemical measurements of components of the renin-angiotensin system in cardiac tissue. It has recently been demonstrated that the genes coding for renin and angiotensinogen are expressed in all regions of the heart, an essential prerequisite for the postulated intracardiac biosynthesis of these proteins. Moreover, we have shown the presence of a functional and physiologically active pathway for the conversion of angiotensin I to angiotensin II in the beating mammalian heart. This conversion appears to be catalyzed by a specific cardiac converting enzyme that is susceptible to systemically administered converting-enzyme inhibitors. Evidence for the physiologic importance of the cardiac renin-angiotensin system comes from experimental data as well as indirect clinical evidence. The potent coronary vasoconstrictor properties of angiotensin II underscore its possible significance in myocardial ischemia and ischemic heart disease, in particular when viewed in the context of selective local activation. The long-known positive inotropic effects of angiotensin II are based on its direct myotropic properties and on its facilitatory effects on sympathetic neurotransmission and may be of added significance in metabolically compromised states. We have recently demonstrated that locally generated angiotensin may be a dominant etiologic factor in the pathogenesis of reperfusion arrhythmias. In addition, we have found experimental evidence for a deleterious effect of angiotensin II on myocardial metabolism in the setting of regional myocardial ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1988

[Hydrocephalus after aneurysmal subarachnoid hemorrhage].

Diagnosis of hydrocephalus after aneurysmal subarachnoid hemorrhage has been facilitated by CT, but the true incidence and pathogenesis of the condition remain to be clarified. Extent of ventricular dilatation does not necessarily correlate with clinical symptoms and the indication of shunting operation is by no means definite. Consecutive 117 patients with ruptured aneurysm were retrospectively studied for possible factor(s) for development of hydrocephalus in the chronic stage. The incidence of chronic hydrocephalus was found to be high in those patients with aneurysm of the anterior communicating artery, those harboring acute hydrocephalus, those admitted with higher clinical grades, those showing thick clots and gyral enhancement on initial CT, and those who received tranexamic acid in excess of 30 g.

Adult↗
PubMed1987

Enhanced responsiveness to parathyroid hormone and induction of functional differentiation of cultured rabbit costal chondrocytes by a pulsed electromagnetic field.

Pulsed electromagnetic fields promote healing of delayed united and ununited fractures by triggering a series of events in fibrocartilage. We examined the effects of a pulsed electromagnetic field (recurrent bursts, 15.4 Hz, of shorter pulses of an average of 2 gauss) on rabbit costal chondrocytes in culture. A pulsed electromagnetic field slightly reduced the intracellular cyclic adenosine 3',5'-monophosphate (cAMP) level in the culture. However, it significantly enhanced cAMP accumulation in response to parathyroid hormone (PTH) to 140% of that induced by PTH in its absence, while it did not affect cAMP accumulation in response to prostaglandin E1 or prostaglandin I2. The effect on cAMP accumulation in response to PTH became evident after exposure of the cultures to the pulsed electromagnetic field for 48 h, and was dependent upon the field strength. cAMP accumulation in response to PTH is followed by induction of ornithine decarboxylase, a good marker of differentiated chondrocytes, after PTH treatment for 4 h. Consistent with the enhanced cAMP accumulation, ornithine decarboxylase activity induced by PTH was also increased by the pulsed electromagnetic field to 170% of that in cells not exposed to a pulsed electromagnetic field. Furthermore, stimulation of glycosaminoglycan synthesis, a differentiated phenotype, in response to PTH was significantly enhanced by a pulsed electromagnetic field. Thus, a pulsed electromagnetic field enhanced a series of events in rabbit costal chondrocytes in response to PTH. These findings show that exposure of chondrocytes to a pulsed electromagnetic field resulted in functional differentiation of the cells.

Alprostadil↗
PubMed1987

Methyl ester of prostaglandin D2 as a delivery system of prostaglandin D2 into brain.

We examined the permeability of the blood-brain barrier to a methyl ester of prostaglandin D2 and the brain uptake was assessed by radioactivity measurements and radioimmunoassay. When the methyl ester (1 mg/kg) was administered intravenously into mice, it was rapidly taken up by the brain (189 ng/g brain at 30 s) and disappeared from the brain with a half-life of 9 s, whereas it was hardly detectable in the blood. The methyl ester transported into the brain was hydrolyzed to prostaglandin D2 and the time course of prostaglandin D2 levels showed an accumulation phase with a peak at 30 s. The total amount of prostaglandin D2 and its methyl ester was 279 ng/g brain at 30 s after injection, corresponding to 0.5% of the administered dose and being 6-times higher than that after prostaglandin D2 injection. The advantage of the methyl ester over prostaglandin D2 for brain uptake was observed at doses higher than 0.2 mg/kg where the methyl ester which escaped from hydrolysis in the blood was taken up more effectively than prostaglandin D2. In in vitro experiments, the esterase activity on the methyl ester was shown to be 20-times greater in the plasma than in the brain homogenate. These results indicate that the esterification of prostaglandin D2 may serve as a good system for the delivery of prostaglandin D2 into the brain.

Animals↗
PubMed1987

Combined effects of somatomedin-like growth factors with fibroblast growth factor or epidermal growth factor in DNA synthesis in rabbit chondrocytes.

The somatomedin-like growth factors cartilage-derived factor (CDF) and multiplication-stimulating activity (MSA) stimulate DNA synthesis and proliferation of rabbit costal chondrocytes under serum-free conditions. Previously, we suggested that CDF and MSA act on chondrocytes in an early G1 phase to stimulate DNA synthesis. CDF and MSA have synergistic effects with epidermal growth factor (EGF) or fibroblast growth factor (FGF) in stimulating DNA synthesis of the cells. The mode of combined action of CDF or MSA with EGF or FGF in chondrocytes was studied by sequential treatments with these agents. EGF or FGF had synergistic effects with CDF or MSA in stimulating DNA synthesis, even when added 10 h after the latter. Synergism was also observed in cells pretreated with CDF or MSA; That is, the cultures were treated for 5 h with CDF or MSA and then washed, and treated with FGF or EGF. However, when CDF or MSA was added more than 5 h after EGF or FGF, no synergism of effects was observed. These findings suggest that the cultured chondrocytes become activated to interact with FGF or EGF for commitment to DNA synthesis when they are exposed to somatomedin-like growth factors at an early stage in the G1 phase. Thus chondrocytes are under a different mechanism of growth control from fibroblastic cells.

Animals↗
PubMed1987

Acetoacetyl-CoA thiolase of Bradyrhizobium japonicum bacteroids: purification and properties.

Acetoacetyl-CoA thiolase of Bradyrhizobium japonicum bacteroids has been purified greater than 130-fold. The enzyme has a molecular weight of 180,000 +/- 15,000 and consists of four identical subunits of 44,000 +/- 2,000. The enzyme was specific for acetoacetyl-CoA; ketodecanoyl-CoA did not serve as a substrate. Catalysis proceeds via a ping-pong mechanism. Iodoacetamide effectively inhibited the enzyme but acetoacetyl-CoA provided considerable protection against this compound. Magnesium was found to inhibit both the thiolysis reaction and the condensation reaction. Acetoacetyl-CoA thiolysis activity was not affected by potassium, ammonium, or several organic acids but was found to be inhibited by NADH. The inhibition by NADH may have an effect during the decline of the symbiosis.

Acetyl-CoA C-Acetyltransferase↗
PubMed1987

Clivus chordoma in childhood.

A 9-year-old boy with mild left hemiparesis and left abducens nerve palsy was found to have chordoma of the clivus. Magnetic resonance imaging (MRI) was most useful not only for diagnosis but also for selection of operative approaches. The tumor was subtotally resected by a transoral-transpharyngeal approach followed by a retroauricular retromastoid craniotomy, and postoperative radiation therapy was administered. Intracranial chordomas are rare in children; only 12 cases have previously been reported in detail. Eleven patients were male and one was female. Progressive cranial nerve involvement and long tract signs without increased intracranial pressure constitute the cardinal symptomatology of intracranial chordomas, but a separation of cranial sutures and enlargement of the head may be seen in children. The role of MRI in diagnosis and patient management cannot be overemphasized.

Brain Neoplasms↗
PubMed1987

Effect of vanadate on cartilage-matrix proteoglycan synthesis in rabbit costal chondrocyte cultures.

The effect of vanadate on proteoglycan synthesis by cultured rabbit costal chondrocytes was examined. Rabbit chondrocytes were seeded at low densities and grown to confluency in medium supplemented with 10% fetal bovine serum, and then the serum concentration was reduced to 0.3%. At the low serum concentration, chondrocytes adopted a fibroblastic morphology. Addition of 4 microM vanadate to the culture medium induced a morphologic differentiation of the fibroblastic cells to spherical chondrocytes, and increased by two- to threefold incorporation of [35S]sulfate and [3H]glucosamine into large, chondroitin sulfate proteoglycans. The stimulation of incorporation of labeled precursors reflected real increases in proteoglycan synthesis, in that chemical analyses showed increases in the accumulation of macromolecules containing hexuronic acid and hexosamine in vanadate-maintained cultures. However, vanadate had only a marginal effect on [35S]sulfate incorporation into small proteoglycans and [3H]glucosamine incorporation into hyaluronic acid and chondroitinase AC-resistant material. These results provide evidence that vanadate selectively stimulates the synthesis of proteoglycans characteristically found in cartilage by rabbit costal chondrocyte cultures.

Animals↗