Synthesis of artificial N-glycopolypeptides carrying N-acetyllactosamine and related compounds and their specific interactions with lectins

Artificial N-glycopolypeptides carrying N-acetyllactosamine (LacNAc) or related compounds were synthesized. First, sugars were converted into their corresponding beta-glycosylamines with ammonium hydrogen carbonate. Then, the beta-glycosylamines were condensated with the carboxyl groups of poly(L-glutamic acid). N-Glycopolypeptides with different degrees of substitution of sugars were isolated by passage through a column of Sephadex G-25. These synthetic polymers were used as model compounds in the analysis of oligosaccharide-lectin interactions. Interactions with some lectins were investigated by agar-gel double-diffusion tests and in terms of inhibition of hemagglutination. A glycopolypeptide substituted with LacNAc reacted with Erythrina cristagalli agglutinin (ECA), peanut (Arachis hypogaea) agglutinin (PNA), Ricinus communis agglutinin-120 (RCA120), wheat germ (Triticum vulgaris) agglutinin (WGA) lectins, which recognize either galactosyl or N-acetylglucosamine (GlcNAc) residues. Other synthetic glycopolymers carrying N-acetylisolactosamine, GlcNAc, N,N'-diacetylchitobiose, or N,N', N"-triacetylchitotriose also reacted with WGA, and these last two polymers inhibited hemagglutination most. Of these five glycopolypeptides, only the one substituted with LacNAc reacted with ECA. These sugar-substituted glycopolypeptides interacted specifically with the corresponding lectins, no matter how much shorter the sugar side chains of the glycopolymers were than those of natural glycoproteins.

Interleukin-13 receptor alpha' but not alpha chain: a functional component of interleukin-4 receptors

In hematopoietic cells, interleukin-2 receptor (IL-2R) gamma chain (termed gammac) is shown to be a component of the IL-4R system, whereas in nonhematopoietic cells, gammac is absent and it is not a component of the IL-4R system. Here, we show that the IL-13R alpha' chain (termed IL-13Ralpha') but not the IL-13R alpha chain (termed IL-13Ralpha) can substitute for gammac and, thus, IL-13Ralpha' forms a novel component of the IL-4R system. This conclusion was drawn on the basis of chemical cross-linking, immunoprecipitation, the ability of IL-13Ralpha' but not IL-13Ralpha to augment IL-4 binding affinity, and the requirement of IL-13Ralpha' for IL-4-induced STAT6 activation in Chinese hamster ovary (CHO) cells transfected with various receptor subunits. Cotransfection of IL-4 receptor p140 (termed IL-4Rbeta) with gammac or IL-13Ralpha' increased IL-4 binding affinity and allowed for STAT6 activation in response to IL-4. However, cotransfection of all three chains did not further increase IL-4 binding or alter the extent of STAT6 activation suggesting that all three chains together do not seem to participate in IL-4 function. Instead, IL-4Rbeta heterodimerizes with gammac or IL-13Ralpha' and mediates STAT6 activation. Cotransfection of IL-4Rbeta with IL-13Ralpha neither increased IL-4 binding affinity nor allowed for STAT6 activation in response to IL-4 indicating that IL-13Ralpha does not convert binding affinity nor transmit signals for IL-4. Because IL-4 phosphorylates JAK1 and JAK2 tyrosine kinases in nonhematopoietic cells, we investigated whether JAK1 and JAK2 are required for IL-4-induced STAT6 activation in various transfectants. Cotransfection experiments with different chains of IL-4R and kinase-deficient JAK1 and JAK2 mutants in CHO cells showed that JAK1 and JAK2 are required for optimal activation of STAT6 in the alpha' beta transfectant but only partially in the beta gammac transfectant. Taken together, our results show that IL-13Ralpha' is a novel functional component of the IL-4R system and that JAK1 and JAK2 mediate IL-4-induced optimal activation of STAT6 in nonhematopoietic cells.

A method for motion compensation of a moving nematode Caenorhabditis elegans and its application to frequency analysis of pharyngeal pulsation

A new sequential image processing method for motion compensation of a moving object with stringy shape has been developed for estimating the pharyngeal pulsation of the nematode Caenorhabditis elegans under several environmental conditions. The method is based on the pixel data transfer on a new image frame while changing the boundary shape and the position but preserving the conformation of the inner structure of an object. All digitized image frames of C. elegans were first converted to motion-compensated images to arrange the pulsation site in the same region of the every transformed frame. The pulsation site was then automatically detected by determining the pixels where the temporal brightness variation was much larger than that of the other pixels. Finally, the pulsation frequency was determined by the Fourier analysis. The validity of our method has been confirmed by analyzing various test data, and the method has been applied for detecting the pharyngeal pulsation frequencies of C. elegans on some environmental conditions, i.e. feed bacteria-free/rich, doping of nerve inactivating ethyl-alcohol and nerve stimulant neurochemical substance of serotonin. The motion compensation method automatically provided reasonable pulsation frequencies which were found to be comparable to those obtained by manual counting. Thus the method is useful for systematic investigations on the variation of pharyngeal pulsation associated with the activity change of the nervous system in environments.

Patent ductus arteriosus and neonatal death in prostaglandin receptor EP4-deficient mice

The physiological role of the prostaglandin E2 receptor EP4 subtype was investigated by generation of EP4-deficient-mice by gene targeting. Loss of the EP4 receptor was not lethal in utero, but most EP4 (-/-) neonates became pale and lethargic approximately 24 h after birth and died within 72 h. Less than 5% of the EP4 (-/-) mice survived and grew normally more than a year. Histological examination revealed that the ductus arteriosus in dead neonates remained open, while it was partially closed in the survivors. In situ hybridization study showed that EP4 mRNA was strongly expressed in the ductus. These results suggest that neonatal death is at least partly due to patent ductus arteriosus and that the EP4 receptor plays a role in regulation of the patency of this vessel. They also indicate that normal function of the EP4 receptor is essential in neonatal adaptation of the circulatory system.

X-ray absorption of bromonaphthalene dissolved in supercritical fluid xenon

The results of Br K-edge X-ray absorption measurements of 1-bromonaphthalene dissolved in supercritical fluid Xe are reported. As the pressure of Xe confined in a high-pressure cell is increased, the absorption spectrum of bromonaphthalene gradually appears, showing that Xe in the supercritical fluid state solvates the bromonaphthalene molecule. The spectrum of the dissolved sample shows a remarkable difference from that of the pure liquid sample in the near-edge region of the X-ray absorption spectrum, reflecting the interaction of the solute material with solvent Xe. Ab initio full multiple-scattering calculations can reproduce the spectral features qualitatively. A large value of the Debye-Waller factor must be introduced to give the best fit, corresponding to a large degree of spatial disorder and violent thermal vibration of the Xe atoms around the Br atom.

Studies on hyperthermia combined with arterial therapeutic blockade for treatment of tumors: (Part III) effectiveness of hyperthermia combined with arterial chemoembolization using degradable starch microspheres on advanced liver cancer

Arterial chemoembolization using degradable starch microspheres and adriamycin was combined with hyperthermia to treat advanced liver cancer. The prolonged peak adriamycin level in hepatic venous blood suggested that the drug persisted for longer in the liver after injection containing microspheres. Heating efficiency was increased more in tumor tissue than in normal liver tissue after embolization. This combined therapy was performed in eight patients with advanced liver cancer and was effective in three (complete or partial remission). The mean survival time was 25 weeks and there were no severe side effects. This combined therapy may be useful for liver cancer.

Studies on hyperthermia combined with arterial blockade for treatment of tumors: (Part I) effectiveness of hyperthermia combined with arterial ligation

Arterial ligation was combined with hyperthermia in rabbits with VX2 tumors implanted in the leg. For seven days after arterial ligation, blood flow was decreased and the pH was low in both normal muscle and tumor tissue. The temperature of normal muscle and tumor tissue increased faster and reached a higher level on heating immediately after ligation than without ligation. The antitumor effect of hyperthermia was stronger immediately after ligation than two or seven days afterwards. However, damage to normal muscle was severe with this combination therapy, so a better method of therapeutic arterial blockade is needed.

Echocardiographic evaluation of cardiac valvular abnormalities in adults with Down's syndrome

It is well known that congenital heart abnormalities are common in children with Down's syndrome. However there are few studies on cardiac abnormalities in adults with Down's syndrome. Therefore, we estimated cardiac abnormalities by means of echocardiography in 30 institutionalized Japanese adults with Down's syndrome, but without cardiac symptoms. Two-dimensional echocardiography showed an incidence of 26.7% in mitral valve prolapse and 20% increase of echo brightness in the mitral valve. Doppler echocardiography revealed an incidence of 16.7% in mitral valve regurgitation, and 13.3% in aortic valve regurgitation. Thus, even adults with Down's syndrome who are apparently free of cardiac symptoms may be at risk for valvular disease.

Studies on hyperthermia combined with arterial blockade for treatment of tumors: (Part II) effectiveness of hyperthermia combined with arterial embolization using degradable starch microspheres

The efficacy of temporary arterial embolization using degradable starch microspheres combined with hyperthermia was investigated in rabbits bearing VX2 tumors. Microsphere injection caused a marked decrease of tumor blood flow and pH. During heating, there was a marked increase of the maximum temperature in tumor tissue compared with normal muscle. Tumor growth was suppressed 330% times at 3 weeks after hyperthermia alone and 270% times following combined treatment with microspheres and hyperthermia. Damage to normal muscle tissue was mild. In conclusion, this combination therapy may be useful for causing selective tumor damage and reducing the effect on normal tissues.

[Extreme decrease of serum total cholesterol and other lipid levels in elderly inpatients]

In this study 112 elderly inpatients (55 men, 57 women) were recruited. 1. Twelve elderly inpatients (5 men, 7 women) aged 82.5 +/- 7.4 years (M +/- SD) were investigated during 3 periods of dietary intake: good intake (period I), tube nutrition (period II) and fasting with intravenous fluid infusion (period III). Calorie, protein, carbohydrate, fat and cholesterol intakes were greater in period I than in periods II and III. Serum total and LDL cholesterols were lowest in period III, when serum HDL cholesterol, triglyceride and total protein were lower in period III than in period I. 2. One hundred elderly inpatients (50 men, 50 women) were divided into 4 groups according to type of decreased serum lipid and a control group. Serum total cholesterol only was decreased in group I, both serum total and HDL cholesterols were decreased in group II, both serum total cholesterol and triglyceride were decreased in group III, all 3 lipids were decreased in group IV and lipid levels did not change in the control group. There were 5 patients in group I, 28 patients in group II, 20 patients in group III, 27 patients in group IV and 20 patients in the control group. The patient's age ranged from 80.3 to 88.4 years and body mass index ranged from 14.7 to 18.4 kg/m2. Serum total protein decreased significantly in groups II-IV, to 5.6 to 5.7 g/dl. Serum total protein, and total cholesterol correlated positively (r = 0.525, p < 0.01), as did Calorie ingestion and serum total cholesterol levels (r = 0.554, p < 0.001). Therefore, severe hypocholesterolemia was accompanied by malnutrition and a decrease in Calorie or cholesterol intake. Serum total cholesterol levels during observation decreased most in group IV, followed by group II similar to serum HDL cholesterol levels. The amount of nutrient intake was smallest in group IV resulting in an extreme lowering of all 3 serum lipid levels.

Retrovirus-mediated gene transfer targeted to retinal photocoagulation sites

Diabetic retinopathy is a major cause of acquired blindness due to the development of retinal neovascularization and associated traction retinal detachment. It is commonly treated with retinal photocoagulation therapy; however, progression to blindness remains a significant problem. To determine the feasibility of adjunctive anti-angiogenic gene therapy, we evaluated the capability of retroviral vectors, which transfer exogenous genes only into dividing cells, to transfer and express a beta-galactosidase gene selectively into photocoagulation sites. Thirty-five rabbits received 30 retinal photocoagulation burns in the right eye followed 2 days later by beta-galactosidase (G1nBgSvNa) or control (G1XSvNa) vector injection into the subretinal space. Beta-galactosidase expression was observed in the photocoagulation sites from 5 days after vector administration (31.7+/-7.0%) to 12 weeks (6.7+/-3.4%). Immunohistochemical studies of the treated retinas using antibody Ber-MAC3 and anti-cytokeratin antibodies revealed that transduced cells were macrophages and retinal pigment epithelial cells. To determine feasibility in a primate, two monkeys received 10 laser burns in the macula superior to the fovea followed 2 days later by G1nBgSvNa vector. beta-galactosidase expression was found in photocoagulation sites and foveal retina was well preserved. We conclude that gene transfer to retinal photocoagulation sites provides stable expression of the transduced gene with relatively high efficiency. This feasibility study suggests the possibility of transferring genes encoding for anti-angiogenic factors into photocoagulation sites to improve the efficacy of laser photocoagulation therapy.

Detection of retinyl palmitate and retinol in the liver of mice injected with excessive amounts of retinyl acetate

The transport of subcutaneously injected retinyl acetate (RA, 100,000 IU/mouse, 105,470 nM) was investigated in male ICR mice (10-week-old) at 0, 3, 6, 12, 18, 24 and 72 hr after a single injection. The retinol and retinyl palmitate levels of liver homogenates, bile in the gallbladder and serum from peripheral blood were measured by high performance liquid chromatography (HPLC) method. Retinyl palmitate in the lipid droplets of hepatocytes and Ito cells was localized by a modified gold chloride staining method. Accumulation of retinyl palmitate peaked at 12 hr post-injection and decreased thereafter until 24 hr post-injection. Fluorescence microscopy revealed many fluorescent vitamin A-containing lipid droplets in hepatocytes around central veins at 12 hr post-injection, but such droplets were not observed in the vehicle control mice or at in the RA-injected mice after 18 hr of injection. Electron microscopic observation also indicated that many retinyl esters-containing lipid droplets were observed in hepatocytes around the central veins at 12 hr post-injection, but no droplets were seen in the controls or 18 hr post-injection. The retinyl palmitate levels in liver homogenates assessed by HPLC decreased from 12 to 24 hr post-injection and increased significantly in bile, while retinol in liver homogenates and serum markedly increased. One of the morphological alterations was intense vacuolization in hepatocyte cell cords from the portal toward the central vein observed at 24 hr post-injection. Transitional lipid droplets between vacuoles and lipid droplets were identified in those hepatocytes. These results of HPLC analysis of retinol and retinyl palmitate in liver homogenates, serum, and bile, together with the results of gold chloride staining suggested that subcutaneously injected RA was first incorporated in hepatocytes at 12 hr and then partially metabolized through vacuoles, transferred into the blood and secreted into the bile over a 24 hr period. Many retinyl esters-containing lipid droplets were visualized in Ito cells at 72 hr post-injection. Most of vitamin A in the liver homogenates measured by HPLC was retinyl palmitate. Therefore, the contents in those lipid droplets might be retinyl palmitate.

Analysis of cell kinetics after irradiation by flow cytometry: proliferative ability of G2-blocked cells after cell sorting

Irradiation, dose-dependently, increases the percentage of cells in the G2 + M phase and the duration of cell cycle arrest, reflected by changes in cell kinetics in the first 48 h. Cells in the G2 + M phase are considered radiosensitive but little is known about their proliferative ability. We studied proliferative ability of irradiated G2 phase-arrested cells following flow cytometric cell sorting using fluorescent Hoechst 33342 staining. Although proliferative ability of non-irradiated cells was not different between G1 and G2 + M phases, cells arrested in G2 + M after irradiation, especially at higher doses, showed less ability than cells in G1. Proliferative ability also correlated well with of G2 block duration.

Structure of and signal transduction through interleukin-4 and interleukin-13 receptors (review)

We have recently demonstrated that two different forms of IL-4R exist; classical or alternative. The classical IL-4R is predominantly expressed in hematopoietic cells and consist of IL-4R and IL-2Rgammac (gammac) chains. On the other hand, alternative form of IL-4R is predominantly expressed in non-hematopoietic cells and consists of IL-4R and IL-13Ralpha' chains. Moreover, the alternative form of IL-4R is also utilized as a functional component IL-13R complex. It has been shown that the phosphorylation and activation of JAK3 tyrosine kinase is crucial for IL-4 activation of STAT6 in hematopoietic cells. However, we have recently demonstrated that non-hematopoietic cells lack JAK3 expression. We also demonstrated that in these cells, STAT6 activation is mediated through JAK1 and JAK2 tyrosine kinases instead. Furthermore, our results show that IL-4 and IL-13 signals are transmitted through the alternative form of IL-4R in these cells. Thus, major differences exist between hematopoietic and non-hematopoietic cells with regard to structure and signal transduction through IL-4R and IL-13R systems.

Enhancement of thermoradiotherapy by glucose administration for superficial malignant tumours

The effect of hyperglycemia on the thermoradiotherapy of superficial malignant tumours was investigated. Glucose administration alone (500 ml of 10% glucose by intravenous drip infusion) reduced the tumour blood flow, when measured by laser Doppler flowmetry, to 66.1% of the baseline level at 30 minutes after the beginning of glucose infusion. Forty patients received glucose in tandem during the hyperthermia and radiotherapy (group A), and 38 patients received thermoradiotherapy alone (group B). The mean Tave (the average temperature of all intratumoural sensors) in group A was 43.4 +/- 1.1 degrees C while that in group B was 42.5 +/- 1.2 degrees C, i.e., glucose administrations significantly increased the tumour temperature (p < 0.01). In group A, complete tumour response (CR) was observed in 12 patients (30.0%), partial response (PR) in 25 patients (62.5%) and no response (NR) in three patients (7.5%). In group B, seven (18.4%), 20 (52.7%) and 11 (28.9%) patients showed CR, PR and NR, respectively. The tumour response rates were significantly different between two treatment groups (p < 0.05). The frequency of side effects of hyperthermia in groups A and B were 22.5 and 21.1%, respectively. This study suggests that hyperglycemia enhances the effectiveness of thermoradiotherapy.

Residual leukemic cell counts in the bone marrow at the end point of intensive induction therapy may be a prognostic factor for acute myeloblastic leukemia in adults

Between January 1990 and May 1994, 59 previously untreated adult patients with acute myeloblastic leukemia (AML) were treated with a combination of behenoyl-cytosine-arabinoside (BHAC), daunorubicin (DNR), 6-mercaptopurine (6-MP) and prednisolone (PSL). Forty one patients (69.5%) achieved complete remission (CR). The Kaplan-Meier analysis revealed an actuarial probability for remaining in remission of 36% in patients who achieved remission and a survival of 29% in all patients at 5 years. A favorable factor relative to achieving CR was performance status (P=0.04). In addition the presence of 300 cells/microl or less of residual leukemic cell counts in the bone marrow at the end point of induction therapy tended to favor remission (P=0.06) using the multivariate analysis with a multiple logistic regression model. In addition the residual leukemic cells counts of less than 300/microl in the bone marrow at the end point of induction therapy was the most significant factor for durable remission (P=0.05) by the Cox's proportional hazard model. We concluded that residual leukemic cells counts in the bone marrow at the end point of intensive induction therapy is a valuable prognostic factor for adults receiving response-oriented individualized induction therapy for AML.

The effect of neuronal perturbation on the uptake of [18F]2-fluoro-2-deoxy-D-glucose in brain slices of the rat

The positron-emitting radionuclide 18F was used to label 2-fluoro-2-deoxy-D-glucose producing [18F]2-fluoro-2-deoxy-D-glucose ([18F]FDG), and subsequently applied to sagittally-sectioned brain slices of the rat to evaluate the activity of neurons for up to 7 h in living brain slices. The amount of [18F]FDG uptake, which is proportional to the activity of neurons, was monitored every 20 min in five representative brain regions: frontal cortex, caudate-putamen, thalamus, hippocampus and cerebellum. The uptake of [18F]FDG linearly increased with time in these areas, showing constant glucose utilization. The rate of uptake was reversibly decreased by tetrodotoxin (TTX) regardless of brain region, but some uptake was insensitive to TTX. There was a tendency for the uptake to be decreased in Ca2+-free, 5 mM Mg2+ (2 mM EGTA) solution, suggesting some remaining functional synapses. Thus in sagittally-sectioned brain slices, most glucose metabolism is dedicated to neuronal firings and some metabolism to synaptic activities and to other functions of neurons and glial cells. When Cd2+ was applied to brain slices at 0.1-1 mM, the curve of [18F]FDG uptake irreversibly declined, indicating its toxic effect rather than its blocking action of transmitter release at synapses. The cerebellum was the most sensitive to Cd2+, and the caudate-putamen was the least sensitive. The present method, therefore, can be also used as a rapid examination system for checking neurotoxicity of substances.

Chemo-enzymatic synthesis of galactosylmaltooligosaccharidonolactone as a substrate analogue inhibitor for mammalian alpha-amylase

We performed chemo-enzymatic transformation of maltooligosaccharides into both end-modified oligosaccharidonolactones of potential use as substrate analogue inhibitors for mammalian alpha-amylases. Enzymatic modification of the non-reducing end glucosyl residue of the maltooligosaccharide was first performed by transglycosylation with beta-D-galactosidase from Bacillus circulans. When maltotriose and maltotetraose were the acceptors, the enzyme regioselectively synthesized 4(3)-O-beta-D-galactosyl maltotriose (LG3) and 4(4)-O-beta-D-galactosyl maltotetraose (LG4) from lactose as a donor. LG4 was further selectively hydrolyzed with a specific alpha-amylase to afford 4(2)-O-beta-D-galactosyl maltose (LG2). The anomer hydroxyl groups of LG2 and LG3 were chemically oxidized to give the corresponding lactones, 4(2)-O-beta-D-galactosyl maltobionolactone (LG2O) and 4(3)-O-beta-D-galactosyl maltotrionolactone (LG3O), respectively. LG2O and LG3O, which are competitive inhibitors for mammalian alpha-amylases, exhibited Ki values of the order of 2.8-18.0 microM, with p-nitrophenyl alpha-maltopentaoside (G5P) as the substrate. On 1H-NMR analysis, these oligosaccharidonolactones were shown to be transformed into the corresponding aldonic acid forms with time in an aqueous solution. In this case, the lactone form was essential for the occurrence of the alpha-amylase inhibitor.

[Analysis of tumor vascular density using the window chamber technique]

Vascular structure is indispensable for a tumor to maintain its growth. The structure also affects drug delivery over chemotherapy, and oxygen tension in the tissue during irradiation. Therefore, measuring the vascular density in the tumor will help to reach an expected level or to evaluate the effect of those therapies. Through previous observation, changes in vascular structure, like the vascular density, have been reported. However, the tissue was usually removed from the deceased animal and examined in the microscope. Not many studies have shown changes in one and the same animal's tissue. In this study, we used the dorsal flap window chamber technique, and observed changes in the development of vascular structure and vascular density in a tumor. Window chambers were attached to the backs of 3 rats, and they anesthetized every 24 hours for microscopic observation. Vascular growth in the tumor started 8 to 9 days after implantation. Their average vascular density was about 25%, and this ratio continued till necrosis started in the tumor. "Necrosis occurs in a tumor because its growth is so rapid that the vascular development can not maintain the same speed." This has been a kind of established theory. During observation, we recognized blood stagnation in vessels as the tumor grew, and the relationship between tumor size and its vascular density was significant (r = 0.926). Our data lead us to another conclusion that "Vascular growth is as fast as tumor growth, keeping a ratio of about 25%, but necrosis is caused by deficiency of blood flow circulation."

Analysis of cell kinetics after gamma-ray irradiation using an anti-BrdU monoclonal antibody

The cell cycle was analyzed using double staining with an anti-bromodeoxyuridine (BrdU) monoclonal antibody and propidium iodide (PI). Changes in cell kinetics after irradiation were compared with those seen by the conventional PI-based DNA histogram method. The effect of irradiation on cell kinetics has been studied primarily by counting G2-arrested cells. By the present BrdU method, a rapid transition from G1 to S-phase was observed within 2 h of irradiation, followed by G1 block. Cells in the S-phase progressed to G2+M where they arrested, resulting in a decreased percentage of S cells (<5%). Release of G1 block occurred after 8 h, and G2+M cells returned to G1 after >18 h. The initial G1 arrest induced by irradiation was confirmed for the first time by the present BrdU-PI double staining.

Plasma beta-carotene, retinol, and alpha-tocopherol levels in relation to glycemic control of children with insulin-dependent diabetes mellitus

Plasma beta-carotene, alpha-tocopherol and retinol were measured in 15 female and 5 male children with insulin-dependent diabetes mellitus (IDDM), and the correlations with plasma hemoglobin A1c (HbA1c) and fructosamine were analyzed. Twelve female and 8 male children served as age-matched controls. The plasma beta-carotene and alpha-tocopherol levels of the IDDM children were significantly higher than those of the control children, but there were no differences in plasma retinol or total lipid levels. The plasma beta-carotene level, beta-carotene/retinol ratio and beta-carotene/total lipids ratio each showed significant correlations with serum HbA1c and fructosamine in all subjects studied. Similarly, the plasma alpha-tocopherol level and alpha-tocopherol/total lipids ratio were correlated with these indexes of glycemic control. These findings suggest certain mechanisms may exist to prevent lipid peroxidation and vascular complications in IDDM patients.

Streptozotocin-induced diabetes increases (Ca2+-Mg2+)-ATPase activity in hepatic plasma membranes of rats: involvement of protein kinase C

The alteration in calcium transport in the liver of rats with streptozocin(STZ)-diabetic state was investigated. STZ (6 mg/100 g body weight) was subcutaneously administered in rats, and 1 or 2 weeks later they were sacrificed by bleeding. STZ administration caused a remarkable elevation of serum glucose concentration. Liver calcium content was significantly increased by STZ administration. Hepatic plasma membrane (Ca2+-Mg2+)-ATPase activity was markedly elevated by STZ administration. This increase was completely abolished by the presence of staurosporine (10(-7)-10(-5) M), an inhibitor of protein kinase C, in the enzyme reaction mixture, suggesting an involvement of protein kinase C signalling. Moreover, the STZ-induced increase in liver plasma membrane (Ca2+-Mg2+)-ATPase activity was significantly raised by the presence of okadaic acid (10(-5) and 10(-4) M). Meanwhile, the STZ-increased (Ca2+-Mg2+)-ATPase activity was not appreciably altered by the presence of anti-regucalcin IgG in the reaction mixture, indicating that the activatory protein regucalcin does not participate in the elevation of the enzyme activity. The present study demonstrates that STZ-induced diabetes causes the increase in hepatic plasma membrane (Ca2+-Mg2+)-ATPase activity of rats.