Search PubMed⌕ Search

Biomedical subjects

K Sakamoto

Publications and source records attributed to K Sakamoto.

At least 199 records · Page 11Linked to original sources
PubMed1999

Structural studies of octasaccharides derived from the low-sulfated repeating disaccharide region and octasaccharide serines derived from the protein linkage region of porcine intestinal heparin.

Four octasaccharide serines and three octasaccharides were isolated after heparinase treatment of porcine intestinal heparin. Their structures were characterized by enzymatic digestion in conjunction with HPLC and 500 MHz 1H NMR spectroscopy. Three of the four octasaccharide serines were structurally identical with those isolated previously, whereas one has the unreported structure DeltaHexA(2-sulfate)alpha1-4GlcN(N-sulfate)alpha1-4GlcAbe ta1-4GlcNAca lpha1-4GlcAbeta1-3Galbeta1-3Galbeta1-4Xylbeta 1-O-Ser (DeltaHexA, GlcN, IdceA, and GlcA represent 4-deoxy-alpha-L-threo-hex-4-enepyranosyluronic acid, D-glucosamine, L-iduronic acid, and D-glucuronic acid, respectively). The other three octasaccharides were isolated for the first time as discrete structures and shared the common core hexasulfated sequence DeltaHexA(2-sulfate)alpha1-4GlcN(N-sulfate)alpha1-4IdceAa lpha1-4GlcNA calpha1-4GlcAbeta1-4GlcN(N-sulfate)alpha1-4IdceA (2-sulfate)alpha1-4Gl cN(N,6-disulfate) with one or two additional sulfate groups. The octasaccharides which were derived from the low-sulfated repeating disaccharide region of heparin contained the common trisaccharide sequence -4IdceAalpha1-4GlcNAcalpha1-4GlcAbeta1- [Yamada, S., Yamane, Y., Tsuda, H., Yoshida, K., and Sugahara, K. (1998) J. Biol. Chem. 273, 1863-1871], suggesting the programmed biosynthesis of heparin. These octasaccharides are the largest oligosaccharides isolated so far from the low-sulfated irregular region of heparin. Since oligosaccharides larger than a pentasaccharide appear to potentially exhibit binding activities toward growth factors or other functional proteins, they will be useful for investigating the structural requirement for molecular interactions between heparin and/or heparan sulfate and biologically active proteins. During the course of the present structural studies, we evaluated the NMR data accumulated thus far on heparin oligosaccharides and found several interesting rules on chemical shifts of proton signals affected by the neighboring sugar residues and their sulfation, which will be in turn useful for determining structures of unknown heparin and/or heparan sulfate oligosaccharides based on the proton resonances.

Animals↗
PubMed1999

The quinohemoprotein alcohol dehydrogenase of Gluconobacter suboxydans has ubiquinol oxidation activity at a site different from the ubiquinone reduction site.

Alcohol dehydrogenase (ADH) of acetic acid bacteria functions as the primary dehydrogenase of the ethanol oxidase respiratory chain, where it donates electrons to ubiquinone. In addition to the reduction of ubiquinone, ADHs of Gluconobacter suboxydans and Acetobacter aceti were shown to have a novel function in the oxidation of ubiquinol. The oxidation activity of ubiquinol was detected as an ubiquinol:ferricyanide oxidoreductase activity, which can be monitored by selected wavelength pairs at 273 and 298 nm with a dual-wavelength spectrophotometer. The ubiquinol oxidation activity of G. suboxydans ADH was shown to be two times higher in 'inactive ADH', whose ubiquinone reductase activity is 10 times lower, than with normal 'active' ADH. No activity could be detected in the isolated subunit II or subunit I/III complex, but activity was detectable in the reconstituted ADH complex. Inactive and active ADHs exhibited a 2-3-fold difference in their affinity to ubiquinol despite having the same affinity to ubiquinone. Furthermore, the ubiquinol oxidation site in ADH could be distinguished from the ubiquinone reduction site by differences in their sensitivity to ubiquinone-related inhibitors and by their substrate specificity with several ubiquinone analogues. Thus, the results strongly suggest that the reactions occur at different sites. Furthermore, in situ reconstitution experiments showed that ADH is able to accept electrons from ubiquinol present in Escherichia coli membranes, suggesting the ubiquinol oxidation activity of ADH has a physiological function. Thus, ADH of acetic acid bacteria, which has ubiquinone reduction activity, was shown to have a novel ubiquinol oxidation activity, of which the physiological function in the respiratory chain of the organism is also discussed.

Acetobacter↗
PubMed1999

Endomyocardial biopsy findings in patients with atrioventricular block in the absence of apparent heart disease.

The purpose of this study was to examine the histopathological findings of right ventricular endomyocardial biopsies from ten patients less than 60 years of age (47 +/- 9.8 (mean +/- SD) years) with documented atrioventricular block but without apparent heart disease. They underwent electrophysiological testing, echocardiography, coronary angiography, and right ventricular endomyocardial biopsy. Biopsy specimens were assessed for morphologic changes in myocyte diameter, fibrosis, disarray, and degeneration. Electrophysiological testing demonstrated atrioventricular nodal block in 2, intra-His bundle block in 2, and infra-His bundle block in 6 patients. Histology revealed evidence of myocardial fibrosis with either myocyte hypertrophy or disarray in 7 of the 10 patients. The results of electrophysiological testing did not correlate with the histopathological findings or severity. In one patient, heart failure appeared during the follow-up period. We conclude that patients with atrioventricular block of unknown etiology have histological abnormalities of the ventricular endomyocardium in addition to the conduction system disturbances. We consider such cases as constituting one of the disease groups of cardiomyopathy, and suggest that it is necessary to follow up the clinical course in these patients.

Adult↗
PubMed1999

Oxidative stress induces p21 expression in pancreatic islet cells: possible implication in beta-cell dysfunction.

AIMS/HYPOTHESIS: Prolonged poor glycaemic control in patients with Type II (non-insulin-dependent) diabetes mellitus often causes pancreatic beta-cell dysfunction accompanied by decreases in insulin biosynthesis and beta-cell proliferation. This is well known as a clinical concept called glucose toxicity. Whereas oxidative stress is provoked under diabetic conditions, we examined the possible implication of cyclin-dependent kinase (Cdk) inhibitor p21 (WAF1/CIP1/Sdi1) in beta-cell dysfunction mediated by oxidative stress. METHODS: Oxidative stress was induced in isolated rat pancreatic islet cells by treatment with H(2)O(2) and mRNA expression of p21 and insulin was examined by northern blot analyses. Also, the expression of p21 and insulin mRNA was examined in Zucker diabetic fatty rat. In islet cells p21 was overexpressed using adenovirus and its effect on insulin gene transcription was examined. RESULTS: When oxidative stress was charged on isolated rat pancreatic islet cells, p21 mRNA expression was induced whereas insulin mRNA was decreased. Also, when diabetes developed in Zucker diabetic fatty rats, p21 expression was induced and the insulin mRNA expression was reduced. As support for the implication of p21 in impairment of beta-cell function, the p21 overexpression in the islet cells suppressed the insulin gene transcription. CONCLUSIONS/INTERPRETATION: The expression of cyclin-dependent kinase inhibitor p21, which can be induced by oxidative stress, increases in pancreatic islet cells upon development of diabetes. By suppressing cell proliferation and insulin biosynthesis, the p21 induction is likely to be implicated in the beta-cell glucose toxicity.

Animals↗
PubMed1999

Induction of glycation suppresses glucokinase gene expression in HIT-T15 cells.

AIMS/HYPOTHESIS: Chronic hyperglycaemia in patients with Type II (non-insulin-dependent) diabetes mellitus often leads to a decline in glucose-responsive insulin secretion from pancreatic beta cells, a phenomenon called glucose toxicity. Upon hyperglycaemia, glycation reaction occurs in the beta cells and induces oxidative stress. To understand the molecular basis of the beta-cell glucose toxicity, we investigated the possible effects of glycation on the expression and enzymatic activity of glucokinase, which plays a crucial part in glucose-responsive insulin secretion. METHODS: Glycation and reactive oxygen species were induced in HIT-T15 cells by treatment with D-ribose and effects on glucokinase gene transcription, glucokinase protein amount, glucose phosphorylation activity, and DNA-binding activities of putative glucokinase gene transcription factors were evaluated. RESULTS: When glycation was induced in HIT-T15 cells, the activity of the human glucokinase gene beta-cell-type promoter was suppressed substantially (83% reduction at 60 mmol/l D-ribose). Also, similar reductions in mRNA and protein amounts of glucokinase and in the Vmax of its enzymatic activity were observed. In agreement with the reduction in the promoter activity, the two major transcription factors of the glucokinase gene, the Pal-binding factor and PDX-1, reduced their binding to their target sequences in the glucokinase gene promoter in glycation-induced HIT cells. Because these effects of D-ribose were counteracted by aminoguanidine or N-acetylcysteine, reactive oxygen species, generated by the glycation reaction, appears to be involved in the phenomena. CONCLUSION/INTERPRETATION: The induction of the glycation reaction, which is known to occur in pancreatic beta cells in chronic hyperglycaemia, suppresses the glucokinase gene transcription and its enzymatic activity. Thus, hyperglycaemia-dependent inhibition of glucokinase activity could in part explain beta-cell glucose toxicity.

Acetylcysteine↗
PubMed1999

State transitions by molecules.

In our previous paper, we described a method by which a state machine is implemented by a single-stranded DNA molecule whose 3'-end sequence encodes the current state of the machine. Successive state transitions are performed in such a way that the current state is annealed onto an appropriate portion of DNA encoding the transition table of the state machine and the next state is copied to the 3'-end by extension with polymerase. In this paper, we first show that combined with parallel overlap assembly, a single series of successive transitions can solve NP-complete problems. This means that the number of necessary laboratory steps is independent from the problem size. We then report the results of two experiments concerning the implementation of our method. One is on isothermal reactions which greatly increase the efficiency of state transitions compared with reactions controlled by thermal cycles. The other is on the use of unnatural bases for avoiding out-of-frame annealing. The latter result can also be applied to many DNA-based computing paradigms.

Animals↗
PubMed1999

Post-tetanic potentiation of reciprocal Ia inhibition in human lower limb.

The purpose of this study was to investigate how reciprocal Ia inhibition is changed during muscle fatigue of lower limb muscle, induced with a voluntary contraction or height frequency electrical stimulation. Reciprocal Ia inhibition from ankle flexors to extensors has been investigated in 12 healthy subjects. Hoffmann reflex (H-reflex) in the soleus muscle was used to monitor changes in the amount of reciprocal Ia inhibition from common peroneal nerve as demonstrated during voluntary dorsi or planterflexion and 50 Hz electrical stimulation induced dorsi or planterflexion. The test soleus H-reflex was kept at 20-25% of maximum directly evoked motor response (M response) and the strength of the conditioning common peroneal nerve stimulation was kept at 1.0 x motor threshold. At rest, weak la inhibition was demonstrated in 12 subjects, maximal inhibition from the common peroneal nerve was 28.8%. During voluntary dorsiflexion and 50 Hz electrical stimulation induced dorsiflexion, there absolute amounts of inhibition increased as compared to at rest, and decreased or disappeared during voluntary planterflexion and 50 Hz electrical stimulation induced planterflexion as compared to at rest. During voluntary or electrical stimulation induced agonist muscle fatigue, the inhibition of the soleus H-reflex from the common peroneal nerve was greater during voluntary dorsiflexion (maximal, 11.1%) and 50 Hz (maximal, 6.7%) electrical stimulation induced dorsiflexion than at rest. The inhibition was decreased or disappeared during voluntary planterflexion 50 Hz electrical stimulation induced planterflexion. It was concluded that the results were considered to support the hypothesis that alpha-motoneurones and la inhibitory intemeurones link to antagonist motoneurones in reciprocal inhibition. The diminished reciprocal Ia inhibition of voluntary contraction during muscle fatigue as compared to electrical stimulation, is discussed in relation to its possible contribution to ankle stability.

Adult↗
PubMed1999

Chemical induction of disease resistance in rice is correlated with the expression of a gene encoding a nucleotide binding site and leucine-rich repeats.

Probenazole (3-allyloxy-1,2-benzisothiazole-1,1-dioxide) is an agricultural chemical primarily used to prevent rice blast disease. Probenazole-treated rice acquires resistance to blast fungus irrespective of the rice variety. The chemical is applied prophylactically, and is thought to induce or bolster endogenous plant defenses. However, the mechanisms underlying this effect have not been established. To understand the mode of the chemical's action, we screened for novel probenazole-responsive genes in rice by means of differential display and identified a candidate gene, RPR1. RPR1 contains a nucleotide binding site and leucine-rich repeats, thus sharing structural similarity with known disease resistance genes. The expression of RPR1 in rice can be up-regulated by treatment with chemical inducers of systemic acquired resistance (SAR) and by inoculation with pathogens. RPR1-related sequences in rice varieties seem to be varied in sequence and/or expression, indicating that RPR1 itself is not a crucial factor for induced resistance in rice. However, Southern blot analysis revealed the existence of homologous sequences in all varieties examined. While the role of RPR1 has yet to be clarified, this is the first report of the identification of a member of this gene class and its induction during the systemic expression of induced disease resistance.

Amino Acid Sequence↗
PubMed1999

Low vitamin K intake effects on glucose tolerance in rats.

To investigate the effects of vitamin K (VK) on pancreatic function, intravenous glucose tolerance tests were performed in rats fed with and without low VK diet (including less than 20% required vitamin K1). Plasma glucose and immuno-reactive insulin (IRI) were determined. It was found that at 0 min., plasma glucose and IRI levels in low VK group were slightly less than in the control (glucose, 204.5 +/- 21.7 vs. 229 +/- 19.6 mg/dl, IRI, 6.6 +/- 1.3 vs. 9.3 +/- 1.8 ng/ml mean +/- SEM). At 3 min. after glucose administration, plasma glucose was higher (391.8 +/- 25.6 vs. 371.8 +/- 18.7 mg/dl) and IRI, lower (11.8 +/- 2.1 vs. 18.2 +/- 3.6 ng/ml) in the low VK group. The disappearance rate of plasma glucose in the low VK group at 5-10 min. was significantly less than in the control (6.7 +/- 2.2 vs. 11.9 +/- 1.8 mg/dl/min.). Incremental IRI area at 0 to 5 min. in the low VK group is less than in the control (15.2 +/- 4.4 vs. 25.0 +/- 9.1 ng/ml/min.), but at 5-60 min. and 0-60 min., it was found to be significantly higher compared to the control (210.3 +/- 55.2 vs. 32.5 +/- 47.1 ng/ml/min. at 5-60 min.). Dietary low VK intake would thus appear to induce a tendency of poor early insulin response, and late hyperinsulinemia to the glucose load in rats.

Animals↗
PubMed1999

Changes in plasma enzyme activity after intramuscular injection of bupivacaine into the human biceps brachii.

The purpose of this study was to examine the time course of changes in plasma creatine kinase (CK), lactate dehydrogenase (LDH), aspartate (AST) and alanine aminotransferase (ALT) activity after intramuscular injection of 0.5% bupivacaine (BPVC). A total of 10 mL BPVC was injected into the biceps brachii (two sites, 5 mL per site) of five healthy, male subjects. Blood samples were obtained from the antecubital vein before and 2, 4, 8, 12, 24, 48, 72 and 96 h after the injection. Affected muscle size was visualized using magnetic resonance imaging (MRI), which was performed 4 days after the injection. Plasma CK activity started to increase 2 h and peaked 12 h after the injection. The peak CK activity (470 +/- 62 IU L-1) was approximately four times the pre-injection value (133 +/- 24 IU L-1), and no additional increase was observed after 24 h. Plasma LDH, AST and ALT activities did not change significantly over time. Muscle around the injection sites showed increased T2 signal intensity using MRI. When smaller (2 mL) or larger (20 mL) amounts of BPVC were injected into the biceps brachii in additional experiments, the amount of increase in plasma CK activity appeared to be related to the size of the affected muscle. It was concluded that CK started to leak from damaged muscle cells shortly after the BPVC injection, and the amount of increase in plasma CK activity appeared to reflect the amount of muscle damage.

Adult↗
PubMed1999

Effect of shear stress and a stable prostaglandin I2 analogue on adhesive interactions of colon cancer cells and endothelial cells.

In the process of cancer metastasis, adhesion between cancer cells and endothelial cells is an important early step. In the present study, the effects of shear stress and the adhesion molecules responsible for cancer cell interactions with endothelial cells were investigated in a system similar to in vivo microcirculation. The effect of prostaglandin I2 (PGI2) also was determined. Human colon cancer cell line Colo 201 and human umbilical vein endothelial cells (HUVEC) were used. After HUVEC on a glass slide were incubated with IL-1beta for 4 h, cancer cells in suspension were perfused on HUVEC at wall shear stresses of 5-40 microN/cm2. Experiments were videotaped, and the number of adherent cells were counted. Additionally, the effects of anti-sialyl Lewis a (SLea) MoAb, anti-E-selectin MoAb, and a PGI2 analogue were investigated. Expression of adhesion molecules on cancer cells and HUVEC was assessed using flow cytometry and enzyme immunoassay, respectively. Few cancer cells adhered to HUVEC without IL-1beta; however, many cancer cells adhered to IL-1beta-stimulated HUVEC at low shear stress (5-20 microN/cm2). Cancer cells did not migrate beneath HUVEC. The increased adhesion was inhibited by anti-E-selectin MoAb, anti-SLea MoAb, and a PGI2 analogue. In addition, the PGI2 analogue decreased the surface expression of SLea on Colo 201 cells. These results suggest that Colo 201 cells adhere to IL-1beta-stimulated endothelial cells via SLea and E-selectin under low flow conditions; PGI2 analogues may protect against metastasis by inhibiting cancer cell-endothelial cell interactions.

Adult↗
PubMed1999

Characterization of the ubiquinol oxidation sites in cytochromes bo and bd from Escherichia coli using aurachin C analogues.

Natural aurachin C is the most potent inhibitor of oxidation of ubiquinols by cytochromes bo and bd from Escherichia coli. To probe the structural properties of the substrate oxidation site in the ubiquinol oxidases, we synthesized a systematic set of aurachin C analogues (N-hydroxy-4-quinolone derivatives) and examined how their structure affects their activity towards cytochromes bo and bd, which are structurally unrelated. We found that the presence of the 3-methyl group of the 2-n-decyl and 2-n-undecyl derivatives increased the inhibitory potency towards both enzymes, probably due to a local steric congestion that allows favorable interaction of the alkyl tail with the enzyme. Increase in the chain length of the 3-alkyl tail of the 2-n-undecyl derivatives decreased the inhibitory potency only in cytochrome bo, indicating that the binding site for the alkyl tails of cytochrome bo is smaller than that of cytochrome bd. Based on these findings, we discuss the differences in the molecular mechanism of substrate oxidation by these two terminal ubiquinol oxidases.

Binding Sites↗
PubMed1999

Defining the structural domain of subunit II of the heme-copper terminal oxidase using chimeric enzymes constructed from the Escherichia coli bo-type ubiquinol oxidase and the thermophilic Bacillus caa(3)-type cytochrome c oxidase.

To probe the location of the quinol oxidation site and physical interactions for inter-subunit electron transfer, we constructed and characterized two chimeric oxidases in which subunit II (CyoA) of cytochrome bo-type ubiquinol oxidase from Escherichia coli was replaced with the counterpart (CaaA) of caa(3)-type cytochrome c oxidase from thermophilic Bacillus PS3. In pHNchi5, the C-terminal hydrophilic domain except a connecting region as to transmembrane helix II of CyoA was replaced with the counterpart of CaaA, which carries the Cu(A) site and cytochrome c domain. The resultant chimeric oxidase was detected immunochemically and spectroscopically, and the turnover numbers for Q(1)H(2) (ubiquinol-1) and TMPD (N,N, N',N'-tetramethyl-p-phenylenediamine) oxidation were 28 and 8.5 s(-1), respectively. In pHNchi6, the chimeric oxidase was designed to carry a minimal region of the cupredoxin fold containing all the Cu(A) ligands, and showed enzymatic activities of 65 and 5.1 s(-1), and an expression level better than that of pHNchi5. Kinetic analyses proved that the apparent lower turnover of the chimeric enzyme by pHNchi6 was due to the higher K(m) of the enzyme for Q(1)H(2) (220 microM) than that of cytochrome bo (48 microM), while in the enzyme by pHNchi5, both substrate-binding and internal electron transfer were perturbed. These results suggest that the connecting region and the C-terminal alpha(1)-alpha(2)-beta(11)-alpha(3) domain of CyoA are involved in the quinol oxidation and/or physical interactions for inter-subunit electron transfer, supporting our previous proposal [Sato-Watanabe, M., Mogi, T., Miyoshi, H., and Anraku, Y. (1998) Biochemistry 37, 12744-12752]. The close relationship of E. coli quinol oxidases to cytochrome c oxidase of Gram-positive bacteria like Bacillus was also indicated.

Amino Acid Sequence↗
PubMed1999

Study of the cause of the temperature rise at the muscle-bone interface during ultrasound hyperthermia.

Undesirable temperature rise at the muscle-bone interface has been one of the major problems during ultrasound hyperthermia treatment. In this study, we examined by both computer calculation and phantom experiment the cause of this problem. Ultrasound penetrates a bone in two different waveforms, longitudinal and transversal. The transmission coefficient of these two waves vary greatly with the incident angle. From both theoretical and experimental results, the incident angle dependency of the interface heat was confirmed. When the incident angle is less than the critical angle of the longitudinal wave, the main cause of the temperature elevation is the absorption of the longitudinal wave in the bone. When the incident angle is larger than the critical angle of the longitudinal wave, the transversal wave becomes the major cause of the heat generation. At the incident angles larger than the critical angle of the transversal wave, no temperature rise is produced by the absorption of the ultrasound at the bone; the incident longitudinal wave, strengthened by the reflected wave, is absorbed in the muscle just in front of the bone. The heat generated in the muscle is transported to the interface so that the temperature of the interface and bone increases slightly.

Bone and Bones↗
PubMed1999

The effect of diet on blood vitamin K status and urinary mineral excretion assessed by a food questionnaire.

To assess Vitamin K (VK) status by food questionnaire, healthy young males (32) and females (9) were given a food list of 50 VK rich foods (identified in the 4th edition standard tables of food composition in Japan). After checking the food names and approximate amount eaten for 7 days, early morning blood and urine samples were collected. Prothrombin and hepaplastin was tested and plasma protein induced by VK absence factor II (PIVKA-II), osteocalcin, and calcium, phosphorous and magnesium in plasma and urine were determined. Participants who have a habit of eating natto, a traditional Japanese food very rich in Vitamin K, VK were excluded, and lowest and highest VK consumers were compared (males; lowest 7 vs. highest 7, females; 3 vs. 3). Plasma PIVKA-II levels, and urinary calcium and magnesium excretion of the lowest was significantly higher, but urinary phosphorus was lower, than that of the highest in females. In the natto eaters, daily mean VK intakes and hepaplastin test results of natto eaters were significantly higher, but urinary calcium excretions were lower than that of non natto eaters in males. These results suggest that Daily VK intake estimated from a questionnaire, is well related to real VK status, and also that natto is a good dietary source of vitamin K.

Adult↗
PubMed1999

An imbalance in plasma prostanoids in patients with Raynaud's phenomenon and pulmonary vasospasm.

Raynaud's phenomenon has been suggested as a predisposing factor for pulmonary vasospasm which may lead to pulmonary hypertension, but the occurrence of cold stimulus-induced pulmonary vasospasm has been inconsistent. Such inconsistent pulmonary vascular responses may be caused by differences in the production of endogenous vasodilators and vasoconstrictors among patients. Fourteen patients with Raynaud's phenomenon associated with mixed connective tissue disease (n=10) or systemic sclerosis (n=4) participated in the study. Right heart catheterization was performed before and after a cold pressor test, immersing a hand in cold water (15 degrees C) for 5 min. Plasma levels of 6-keto prostaglandin (PG)F1alpha, thromboxane (TX)B2 and endothelin (ET)-1 in the mixed venous blood were measured. Mean pulmonary artery pressure increased after the cold pressor test in five of 14 patients, and the patients were divided into those with pulmonary vasospasm (responders) and those without vasospasm (nonresponders). After the cold pressor test, levels of 6-keto PGF1alpha increased significantly in nonresponders (p<0.01) and decreased significantly in responders (p<0.05). The ratios of 6-keto PGF1alpha to TXB2 significantly increased in nonresponders (p<0.01) but not in responders and the difference between responders and nonresponders after the cold pressor test was also statistically significant (p<0.05). No significant change in plasma ET-1 levels occurred in either responders or nonresponders. The results suggest that an impaired production of prostaglandin I2 and an imbalance between prostaglandin I2 and thromboxane A2 are associated with the occurrence of pulmonary vasospasm induced by Raynaud's phenomenon.

6-Ketoprostaglandin F1 alpha↗
PubMed1999

Prolongation of the effective duration of cytomedical therapy by re-injecting SK2 hybridoma cells microencapsulated within alginate-poly(L)lysine-alginate membranes into human interleukin-6 transgenic mice.

We previously reported that SK2 hybridoma cells that secreted anti-human interleukin-6 (hIL-6) monoclonal antibodies (SK2 mAb) were microencapsulated within alginate-poly(L)lysine-alginate (APA) membranes (APA-SK2 cells) for immunoisolation, and a single intraperitoneal injection of these APA-SK2 cells remarkably improved IgG1 plasmacytosis in hIL-6 transgenic mice (hIL-6 Tgm). However, the duration of the effectiveness of APA-SK2 cells as a cytomedicine was unfortunately limited. In this study, we attempted to re-inject APA-SK2 cells into hIL-6 Tgm for the purpose of prolonging the cytomedical therapy. In hIL-6 Tgm re-injected with APA-SK2 cells, the plasma IgG1 level did not show any increase in 37 week old mice, and their survival time was at least three times longer than those of untreated hIL-6 Tgm. These results suggest that re-injected APA-SK2 cells survived and secreted SK2 mAb in the allogeneic mice. Thus, the limited duration of the cytomedical effects of APA-SK2 cells was probably caused by the disappearance of the inner space of microcapsules for cell proliferation, not by the rejection of the host's immune system. Therefore, if we can regulate the proliferation of the cells microencapsulated within a semipermeable membrane, we may be able to develop a cytomedicine which will continue its function longer after a single injection.

Alginates↗