bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in ribonucleoprotein particle and chromatin organization induced by liposomes in isolated nuclei
Authors: Maraldi N. M. , Galanzi A. , Caramelli E. , Billi A. M. , Ognibene A. , Rizzoli R. , Capitani S.
Published: May 2005

Nuclei isolated from rat liver, incubated in the presence of liposomes of different phospholipids, undergo typical modifications: chromatin dispersion and reduction of the interchromatin granules in nuclei incubated with negatively charged liposomes and increase of the chromatin density and of the number and size of the interchromatin granules in nuclei incubated with neutral liposomes. The possibility that the observed modifications are caused by an impairment of the transport and translocation of ribonucleoproteins belonging to the inner nuclear matrix, is suggested by the results obtained by radiotracer techniques on the release of RNA from liposome‐incubated nuclei.
The relation between inhibition of glycolysis and stimulation of oxygen uptake due to glucagon in livers from rats in different metabolic conditions
Authors: Bazotte R. B. , Constantin J. , Hell N. S. , Iwamoto E. L. Ishii , Bracht A.
Published: May 2005

The relation between the effects of glucagon on oxygen consumption and glycolysis in livers from rats under different metabolic conditions was examined. Respiration of substrate‐free perfused livers with different glycolytic fluxes, induced by changes in the pattern of food intake, responds differently to the infusion of 1 nM glucagon. The increases in oxygen uptake caused by 1 nM glucagon correlate reasonably well with the absolute decreases in glycolysis. The degree of inhibition of glycolysis is approximately constant (58 per cent) for all metabolic conditions. When no recovery of glycolysis occurs upon cessation of glucagon infusion, the same happens with oxygen consumption, which remains stimulated. It is concluded that in livers with no appreciable biosynthetic activities, the action of glucagon on respiration and glycolysis may be interpreted in terms of an interaction of ‘cytosolic’ and mitochondrial ATP generating processes.
Halothane induced disorder of red cell membranes of subjects susceptible to malignant hyperthermia
Authors: Ohnishi S. Tsuyoshi , Ohnishi Tomoko
Published: May 2005

Membrane fluidity of red blood cells drawn from malignant hyperthermic pigs and humans was studied using spin‐probes and electron paramagnetic resonance technique. The order parameter and rotational correlation time were determined with 12–doxylstearate and 16‐doxylstearate, respectively. It was found that halothane decreased both parameters, but that the decrease of these parameters in subjects susceptible to malignant hyperthermia was much greater than that in normal subjects. The differences were most pronounced at 3 mM halothane. A possibility of using blood for a non‐invasive screening for malignant hyperthermia is discussed.
Angiotensin II vascular receptors in fetal and neonatal rats
Authors: Ghiani Pietro , Uva Bianca M. , Mandich Alberta , Masini Maria Angela
Published: May 2005

Specific binding sites for angiotensin II in aorta and renal arteries have been studied in rat fetuses (18th day of pregnancy) and 1‐day‐old newborn rats by binding studies in arterial membranes using [125I] ileu‐5‐angiotensin II. One type of angiotensin receptor was found both in fetuses and in the newborns; the capacity of this (RT) decreased immediately after birth (from 0·06 ± 0·01 nM to 0·02 ± 0·005 nM; ± SEM) and the affinity (Kd) increased at birth (from 3·5 ± 0·6 nM to 19·5 ± 1·2 nM; ± SEM). Localization of the specific binding sites was studied by autoradiography on arteries from fetal and newborn rats either perfused with iodinated angiotensin II by cannulation of the aorta or in vitro on cryostat sections incubated with the radioactive angiotensin II. Both in fetuses and in the newborn the binding sites were located in the tunica media of the arteries.
Isolation and characterization of parenchymal cells from experimentally induced macronodular rat liver cirrhosis
Authors: Müller Diethard , Franke Hans , Zimmermann Thomas , Dargel Rolf
Published: May 2005

Hepatocytes were isolated from thioacetamide (TAA)‐induced macronodular cirrhotic rat livers by a collagenase perfusion method. In the content of cellular metabolites, fatty acid uptake and lipid secretion there were no substantial differences compared with cells isolated from micronodular cirrhosis described previously. In contrast to isolated hepatocytes from normal livers those from macronodular cirrhosis had a lowered cellular content of triglycerides, phospholipids and cholesterol but not of cholesterol esters and free fatty acids. In macronodular cirrhosis hepatocytes of hypertrophic type, rich in cell organelles, can be distinguished ultrastructurally from those with signs of atrophy and degeneration. Immediately after isolation many hepatocytes isolated from macronodular cirrhosis showed plasma membrane blebbing. Whereas the blebbing was without recognizable effects on the fine structure of the isolated hepatocytes of the hypertrophic type, in the more atrophic ones some mitochondria were swollen. In addition, morphological analysis of the crude and purified suspensions revealed a partial selection of the hypertrophic cells during the isolation procedure, presumably due to a more labile state of those cells which showed signs of atrophy and degeneration. When stabilized in the suspension medium, however, the hepatocytes maintained complex metabolic functions for at least 2 h. Thus, the method described allows the isolation of parenchymal cells from TAA‐induced macronodular cirrhotic livers for studying ultrastructural and biochemical alterations in hyperregenerative experimental liver cirrhosis.
A polyclonal antiserum against the rabbit progesterone receptor recognizes the human receptor: Immunohistochemical localization in rabbit and human uterus
Authors: Zaino Richard J. , Feil Peter D. , Clarke Christine L. , Mortel Rodrigue , Satyaswaroop Pondichery G.
Published: May 2005

A polyclonal antiserum, raised in guinea pigs immunized with the 116 000 Mr rabbit uterine progesterone receptor (PR), was used to demonstrate immunoreactive PR in frozen fixed sections of rabbit and human uterus. In both species, PR localization was exclusively nuclear. For the rabbit uterus, staining intensity was greatest in the myometrium, followed by endometrial stroma, glands, and luminal epithelium. In premenopausal human endometrium and myometrium there was intense staining of nuclei from proliferative phase glands and myometrium. In the secretory phase the glands failed to stain, yet immunostaining persisted in the myometrium.
Lindane‐induced liver oxidative stress: Respiratory alterations and the effect of desferrioxamine in the isolated perfused rat liver
Authors: Videla Luis A. , Simizu Kiyoko , Barros SilVia B. M. , Junqueira Virginia B. C.
Published: May 2005

The effects of lindane administration (25–60 mg kg−1 for 24 h) on hepatic oxygen consumption were studied in the isolated perfused rat liver, in the absence and presence of the iron‐chelator free‐radical scavenger desferrioxamine. Lindane elicits a dose‐dependent enhancement of total oxygen uptake by the liver, which is largely inhibited by 0·55 mM desferrioxamine. Total desferrioxamine‐ sensitive oxygen consumption exhibits a maximal increase (213 per cent) at 60 mg of lindane kg−1 over control values and represents 21 per cent of the total oxygen consumption. At the different doses of lindane used, it was calculated that about 60 per cent of the total increase in oxygen uptake by the liver is accounted for by oxygen related to oxidative stress, probably utilized at different stages of the induced lipid peroxidative process.
Protection against cadmium toxicity and enzyme inhibition by dithiothreitol
Authors: Ahammadsahib Kabeer I. , Jinna Rajender R. , Desaiah Durisala
Published: May 2005

In the present in vivo studies the alterations in cation transporting enzymes of the brain, kidney and liver tissues were assessed at intervals between 0 to 48 h after a single, acute (10 mg kg−1, i.p.) dose of cadmium (Cd). The inhibition of Na+–K+–ATPase during the first 24 h does not parallel the changes in K+–PNPPase suggesting differential effects on phosphorylation and dephosphorylation steps of the overall ATPase reaction. Between 30 min to 2 h the inhibition in enzyme activity was steep (27 per cent in brain, 54 per cent in liver) followed by a rapid reversal between 2–6 h. This critical period may correspond to the time of induction of metallothionin. This enzyme reversal was followed by a significant decrease in Na+–K+ ATPase (40–68 per cent) and K+‐PNPPase (44–60 per cent) between 24 to 48 h. A similar pattern was observed in Ca2+–ATPase in all the three tissues. A 33 per cent mortality was observed in rats after 48 h of cadmium challenge. Administration of dithiothreitol (DTT, 20 mg kg−1, i.p.) to CdCl2 pretreated rats at 24 h resulted in mortality reduced from 33 per cent to 0 and reversal in the inhibition of Na+‐‐K+–ATPase in brain and kidney and Ca2+–ATPase in brain. Since protection of brain and kidney enzymes by DTT paralleled its protection against Cd toxicity, their inhibition by Cd may, in part, constitute the biochemical basis of Cd toxicity.
Acute phase response to recombinant interleukin‐6 and macrophage‐ and fibroblast‐derived crude cytokine preparations in primary cultures of mouse hepatocytes
Authors: Rokita H. , Mackiewicz M. , Koj A.
Published: May 2005

A number of acute phase proteins were determined by electroimmunoassay in media from CBA mouse hepatocytes cultured for 2 days with human recombinant IFN β2/IL‐6, as well as with conditioned media from LPS‐stimulated rat macrophages, and of murine L fibroblasts. It was found that human recombinant IL‐6 caused three‐fold increase in secretion of fibrinogen, while haptoglobin, complement C3 and transferrin were increased respectively, to 168 per cent, 151 per cent, and 145 per cent of the control. DEX(10−7M) in DMEM supplemented with 5 per cent FCS, enhanced the IL‐6 effect on the three positive acute phase proteins. IL‐6 elevated haptoglobin mRNA in mouse hepatocytes to a degree comparable with the concentration of the protein in the culture medium. The effect of conditioned media from murine fibroblasts and peritoneal rat macrophages was generally similar to that of recombinant IL‐6. However, both natural preparations of the cytokines caused decrease in albumin and alpha‐1‐proteinase inhibitor secretion.
A comparison of the effects of various stimulatory agents on t‐PA secretion by normal and malignant cell lines
Authors: Clarke J. , Griffiths B. , Melling J. , Ling R. , Atkinson T. , Electricwala A.
Published: May 2005

Succinyl con A and acetyl con A both stimulated epithelial cells to produce similar yields of tissue plasminogen activator (t‐PA) to those previously obtained with native con A. However, unlike con A, the derivatized lectins did not adversely affect cell morphology and viability, and cells treated with succinyl con A could secrete t‐PA for a prolonged period. Con A and the two derivatives produced similar morphological effects in Bowes melanoma cells, but t‐PA production was not increased. Elevated cyclic nucleotide concentrations did not affect t‐PA production from epithelial cells, but calcium ionophore treatment generated t‐PA yields similar to those obtained with lectins. Azacytidine, which enhanced t‐PA production from epithelial cells, did not increase yields from Bowes melanoma cells, and also sodium butyrate, reported to increase t‐PA yields from human endothelial cells, had no effect on either cell line.
Postnatal changes of cathepsin D activity in rat liver and brain
Authors: Dionyssiou‐Asteriou A.
Published: May 2005

Total and specific activity of cathepsin D (EC. 3.4.23.5) were measured in rat liver and brain from 1 to 98 days of age.

The activity of cathepsin D in the liver of adult and newborn rats was the same while in the rat brain it was higher in adult than in newborn rats. In the liver maximum specific activity of cathepsin D occurred on the 10th postnatal day and minimum on the fourth day of age. In the brain maximum specific activity of the enzyme occurred on the 14th postnatal day. Total activity of cathepsin D increased after birth in rat liver and brain. These results are discussed in relation to the functional role of cathepsin D in the rat liver and the brain.
The activation of phosphatidylinositol‐specific phospholipase C by insulin in mammary epithelial cells of lactating mouse
Authors: Yoshimoto Akio , Nakanishi Keiko , Anzai Tadashi , Komine Senichi
Published: May 2005

We have previously demonstrated in vitro that, in the endoplasmic reticulum and Golgi apparatus of mammary epithelial cells of lactating and pregnant mice, inositol 1,4,5‐trisphosphate releases Ca2+ that has been stored in these organelles. In this study, we examined whether insulin and prolactin, essential for the growth of mammary gland and for lactation, influenced the activity of phosphatidylinositol‐specific phospholipase C in mammary cells. In the plasma membrane fraction of mammary epithelial cells of the DDY mouse strain 5 days after the start of lactation after the first pregnancy, and with phosphatidylinostol as substrate, it was shown that the activity of phospholipase C was enhanced by about four times in the presence of insulin compared with the control. Such enhancement was not found in the membrane fraction treated with prolactin.
Acid‐soluble purine and pyrimidine derivatives of growing, encysting and encystment‐inhibited amoebae
Authors: Cumaraswamy Arunthathi , Henney Henry R.
Published: May 2005

The intracellular acid‐soluble purine and pyrimidine derivatives of myxamoebae‐swarm cells of Physarum flavicomum were investigated during growth, microcyst formation, and during adenine‐inhibiton of encystment, using high performance liquid chromatography (HPLC). We also studied the incorporation of exogenous radioactive adenine into the acid soluble purine derivatives and S‐adenosyl‐sulphur compounds separated by HPLC. The most abundant ribonucleoside monophosphate was AMP in the growing and 15 h encysting cells (NC), while it was UMP in the 15 h adenine‐inhibited cells (AIC). ADP was the nucleoside diphosphate present in the greatest quantity in the growing and NC cells but it was CDP in the AIC. The nucleoside triphosphate in highest concentration was ATP, UTP, and GTP in growing, NC, and AIC, respectively. Guanosine was the most abundant nucleoside in all cells. The nucleobase occurring in greatest concentration was cytosine, cytosine and guanine, and adenine in the growing, NC, and AIC, respectively. The AMP content in the 15 h AIC was 2·1‐fold higher than that of adenosine. The 15 h NC had the lowest adenylate energy charge, a value of 0·54 ± 0·02, while the values for growing cells and the AIC were 0·62 ± 0.02 and 0·76 ± 0.01, respectively. [14C]‐Adenine labelling studies (15 h) revealed the occurrence of purine nucleotide interconversion, as the label was detected not only in adenosine, AMP, ADP, ATP, but also in guanine, guanosine, GMP, GDP, GTP, as well as, in inosine monophosphate and xanthosine monophosphate. The percentage incorporation of the radiolabelled adenine into AMP was higher than into adenosine. An increased intracellular level of guanine nucleotides is associated with the inhibition of encystment. The extracellular adenine, rather than internal adenine sources, appears to be the primary precursor of nucleotide for S‐adenosylmethionine synthesis during adenine‐inhibition of encystment.
Amelioration by menadione of the experimental chronic immune arthritis in the rabbit
Authors: Pitsillides A. A. , Blake S. M. , Glynn L. E. , Bitensky Lucille , Chayen J.
Published: May 2005

The immunological induction of arthritis in the knee of the rabbit is well established as a model for human rheumatoid arthritis. It has the special advantage of allowing the development of the condition, and the effect of disease‐modifying agents, to be followed.

Attention has been focussed on the activity of glucose 6‐phosphate dehydrogenase in the synovial lining cells since the fourfold elevation of this activity was shown to be fundamental in the human condition. An equal elevation of this activity has now been demonstrated in the rabbit model. Furthermore, it has been shown that the oral administration of menadione decreases this activity towards normality with a concomitant decrease in the degree of inflammation.
Phosphorylation by liver glucokinase of D‐glucose anomers at anomeric equilibrium
Authors: Zähner Dagmar , Malaisse Willy J.
Published: May 2005

The relative contribution of each anomer of D‐glucose to the overall phosphorylation rate of the hexose tested at anomeric equilibrium was examined in rat liver postmicrosomal supernatants under conditions aimed at characterizing the activity of glucokinase, with negligible interference of either hexokinase, N‐acetyl‐D‐glucosamine kinase or glucose‐6‐phosphatase (acting as a phosphotransferase). Both at 10° and 30°C, the relative contribution of each anomer was unaffected by the concentration of D‐glucose. At both temperatures, the α/β ratio for the contribution of each anomer was slightly, but significantly, lower than the α/β ratio of anomer concentrations. These findings, which are consistent with the anomeric specificity of glucokinase in terms of affinity, cooperativity and maximal velocity, reveal that the preferred α‐anomeric substrate for both glycogen synthesis and glycolysis is generated by glucokinase at a lower rate than is β‐D‐glucose‐6‐phosphate.
A 33 kDa protein band in enhanced during long‐term adaptation of EUE cells to a hypertonic medium
Authors: Giuliani Attilia , Ferraretto Anita , Conti Anna Maria Fuhrman , De Grada Laura , Fraschini Annunzia , Pellicciari Carlo , Romanini Maria Gabriella Manfredi
Published: May 2005

A cell line derived from human embryonic epithelium (EUE cells) shows an enhanced expression of a 33 kDa protein when adapted to grow in a hypertonic medium containing 0·246 M NaCl (1·8 × the isotonic concentration). The maximum amount of this protein, followed by SDS‐PAGE electrophoresis, was found after 4 days of adaptation; thereafter, the protein band remained fairly constant up to 30 days. When the cells were transferred back to a medium containing 0·137 M NaCl (isotonic medium), the protein pattern reverted to that of control cells. This protein is mainly localized in the cytosol, although a small part is associated with the 150 000 g pellet and needs detergents to be extracted. The molecular weight and the cellular location suggest a possible analogy with the so‐called amphitropic proteins, that are known to interact with both the epidermal growth factor receptor and hydrophobic structures, such as the membrane phospholipids and the cytoskeletal components.
The sensitivity of synthesis of human cartilage matrix to inhibition by IL‐1 suggests a mechanism for the development of osteoarthritis
Authors: Dingle J. T. , Horner A. , Shield M.
Published: May 2005

The damage to articular cartilage, characteristic of arthritic disease, is usually ascribed to increased degradative activity by enzymes or free radicals from locally activated cells.1–3 We propose that inhibition of matrix synthesis, and consequential impairment of the natural repair process, may be at least as important in chronic joint disease.
Cellular thiols in rat liver cell lines possessing different growth characteristics
Authors: Principe Paola , Riley Patrick A. , Slater Trevor F.
Published: May 2005

Thiol levels were measured in three cell lines derived from rat hepatocytes with different growth rates and degrees of tumorigenicity: IAR20 having normal epithelial morphology and no tumour forming ability: IAR6.1 being a chemically‐transformed malignant cell line; and IAR6.1RT7 derived from an epithelial tumour obtained after injection of IAR6.1 cells into a syngeneic animal. The mean levels of GSH, GSSG, low molecular weight thiols (LMWT), macromolecular thiols (MT) and total reactive protein sulphur (TRPS), expressed as nmoles‐SH mg−1 protein, were found to be 25·5, 7·5, 50·1, 114·5 and 143·6 respectively for IAR20; 37·6, 3·9, 65·4, 126·8 and 148·4 for IAR6.1; 17·2, 4·4, 52·3, 141·0 and 168·2 for IAR6.1RT7.

Cultures were treated with D, L‐buthionine‐S, R‐sulphoximine (BSO) to cause greater than 70 per cent depletion of GSH and the measurements of cellular thiols repeated. Although treatment with BSO caused a substantive decrease in the LMWT fraction, there were no major changes in macromolecular thiols or in total reactive protein sulphur. The respective mean values for LMWT, MT and TRPS (expressed as nmoles‐SH mg−1 protein) were 19·4, 109·8, 136·3 for IAR20; 17·2, 119·3, 143·6 for IAR6.1; 21·6, 150·7 and 163·5 for IAR6.1RT7.

It is concluded that significant differences in thiol levels exist between the three rat liver cell lines studied. However, severe acute depletion of GSH is not reflected by changes in the levels of macromolecular thiols which suggests that there is only a slow equilibrium between these two major thiol pools.
Cytophotometric assessment of Feulgen‐DNA and coomassie‐total cell protein in adrenocortical fasciculata cells of noise‐exposed wister rats
Authors: Ballough D. U. , Ballough G. P. , Strauss J. A. , Durkot M. J. , Anthony A.
Published: May 2005

The present investigation was undertaken to examine possible noise‐induced alterations in adrenal fasciculata cell (AFC) metabolism, and also to determine if the magnitude of these changes differs in male versus female rats. Wistar rats approximately 3 months old were exposed to intense noise for 60 min (100 dB, re 2 × 10−5 N(m2)−1, 350–20 000 Hz); control rats were house under identical conditions, at an ambient noise level of 40–60 dB. Adrenal fasciculata cells (AFC) from each animal were examined for noise‐induced alterations in Feulgen‐DNA reactivity (as an indicator of chromatin template activity) and Coomassie‐total cell protein levels using scanning‐integrating cytophotometry. The results provide evidence that intense noise elicited a marked AFC metabolic enhancement in both male and female rats; the degree of this enhancement was more pronounced in males. This disparity may be due to pre‐existing differences in male versus female AFC enzymatic capability and subsequent responsiveness to noise‐induced activation.
Effect of vanadate and ouabain on insulin binding and insulin imprinting in Tetrahymena
Authors: Kovács P. , Hegyesi Hargita , Csaba G.
Published: May 2005

Na‐metavanadate and ouabain that act on Na+K+‐ATPase had no influence on insulin binding to Tetrahymena immediately after treatment, but after 24 h considerably enhanced the binding capacity of generations of progeny. The increase in binding was of a similar magnitude to that elicited by insulin imprinting. Vanadate failed to increase the imprinting potential of insulin while ouabain even prevented insulin imprinting when administered together with insulin, but, did not affect imprinting when administered after insulin. By analogy with higher organisms it appears that inhibition of Na+K+‐ATPase plays no role in the insulin‐like effect of vanadate on the unicellular Tetrahymena, as judged also from the capacity to bind insulin of the generations of offspring.
Restricted expression of recombination activating gene (RAG‐1) in mouse lymphoid tissues
Authors: Yamamoto Akihito , Atsuta Mitsuru , Hamatani Kiyohiro
Published: May 2005

In an attempt to determine the distribution of recombinase activity in the mouse thymus, spleen and lymph nodes, we used the in situ hybridization method to examine the expression of the recombination activating genes RAG‐1 and RAG‐2. Expression of RAG‐1 was found in most cortical thymocytes but not in the majority of medullary thymocytes. Although hybridization signals of RAG‐2 were not as intense as those of RAG‐1, the localization of RAG‐2 transcripts was similar to that of RAG‐1. In the spleen, expression of RAG‐1 was found only in limited cells near the sinus, and the majority of the cells within the follicle were negative for RAG‐1 transcript. In nude mice, RAG‐1‐expressing cells were detected in the same regions, which suggests that in situ hybridization signals of RAG‐1 in the spleen are due to the cells of B cell origin. In the lymph nodes, expression of RAG‐1 was found only in the medullary region. Expression of RAG‐2 transcript in the spleen and the lymph nodes, if any, was too faint to determine the specific localization. These results suggest that most of the cortical thymocytes and some cells in the spleen are capable of rearranging T cell receptor genes and immunoglobulin genes, respectively, but the possibility of some other explanation could not be ruled out in RAG‐1 expressing cells of the spleen and the lymph nodes.
Brain Na+ K+ ATPase and cholesterol in acute experimental trypanosomiasis
Authors: Nok Andrew J. , Esievo K. A. N. , Ukoha A. I. , Ikediobi C. O. , Ibrahim S. , Martins O. , Tekdek B. , Omage J.
Published: May 2005

Brain Na+ K+ ATPase activity has been found to decrease in experimental trypanosomiasis in rats infected with Trypanosoma congolense. Some physical features that affect membrane fluidity were also observed to be altered. The levels of cholesterol in the brain and free fatty acids in the serum were found to increase in the infected animals. These findings might be relevant to the development of brain lesions.
Polymerase chain reaction in the detection of mRNA transcripts from the slow skeletal troponin T (TNNT1) gene in myotonic dystrophy and normal muscle
Authors: Novelli G. , Gennarelli M. , Zelano G. , Sangiuolo F. , Lo Cicero S. , Samson F. , Dallapiccola B.
Published: May 2005

Recent studies have shown that the gene encoding for the slow skeletal troponin isoform T (TNNT1) is located on the proximal long arm of human chromosome 19 in the myotonic dystrophy (DM) region. In order to test TNNT1 as a candidate gene for DM, we have isolated TNNT1 cDNA from skeletal muscle from two healthy individuals and from two patients with DM. Sequencing of the TNNT1 cDNA from the DM and normal muscle revealed two sequence variants but no transcriptionally significant mutations. This work rules out a defect in the coding segment of TNNT1 as a cause of DM and provides a polymerase chain reaction protocol for studying troponin T gene expression.
Effect of streptozotocin‐induced diabetes on the handling of phosphate by the rat small intestine
Authors: Al‐Sawan S. , Skillen A. W.
Published: May 2005

The effect of chemically‐induced diabetes on the handling of phosphate (Pi) by rat jejunal enterocytes has been investigated in the presence of a Na‐ or a choline‐gradient. Pi uptake was significantly increased in both gradients. The Pi efflux rate constants for enterocytes from diabetic rats were similar to those of control rats. The effect of diabetes on both the protein and alkaline phosphatase isoenzymes of the rat small intestinal brush‐border membranes was examined using SDS‐PAGE. The patterns given by membranes from rats 14 days after the induction of diabetes were no different from those of controls.
Abnormalities of DNA in human osteoarthritic articular cartilage
Authors: Macha N. , Older J. , Bitensky Lucille , Chayen J.
Published: May 2005

The normal amount of DNA in human diploid nuclei was determined by the use of the Feulgen reaction measured by microdensitometry. The DNA‐content of nuclei in normal human articular cartilage was determined in nuclei of zones 3 and 4 of cartilage of the femoral head removed from osteoporotic fractured necks of femur. Analysis of the results indicated that a degree of synthesis of DNA occurred even in these zones of very elderly persons. Results on these zones in the articular cartilage of osteoarthritic joints indicated that different populations occurred. In some there was DNA‐synthesis related to tetraploidy; in others, the DNA was very stable to acid hydrolysis with no sign of biosynthetic activity; in the last group, which contained erosions of the superficial zones, the DNA was unstable to hydrolysis.
Homologous priming in chemotactic peptide‐stimulated neutrophils
Authors: Bellavite P. , Chirumbolo S. , Lippi G. , Guzzo P. , Santonastaso C.
Published: May 2005

The kinetics and dose‐dependence of activation of human neutrophils exposed to sequential additions of the chemotactic peptide n‐formyl‐methionyl‐leucyl‐phenylalanine (fMLP) have been investigated by multiwell microplate assays. Treatment of neutrophils with medium–high doses (from 10−8 to 5 × 10−7 M) of fMLP caused activation of superoxide anion (O) production, but prevented further activation by a subsequent addition of an optimal dose (from 10−7 M to 5 × 10−7 M) of fMLP. These findings represent an example of cell desensitization, or adaptation. However, neutrophils treated with low, sub‐stimulatory doses (from 10−10 to 5 × 10−9 M) of the peptide and then treated with optimal doses of fMLP exhibited an O production that was two to three‐fold higher than that induced by the same optimal doses on untreated cells. A similar phenomenon of homologous priming of the oxidative metabolism of neutrophil has not previously been described or characterized. Priming was maximal after about 30 min of incubation with fMLP, which differed from desensitization, which required only a few minutes. Homologous priming was not confined to O production, but was also observed with the release of the granule enzyme, lysozyme. Low doses of fMLP were also capable of triggering an increase of intracellular free Ca2+ and of fMLP membrane receptors, which are possible mechanisms responsible for priming.
Ethanol inhibits phosphatidylcholine and phosphatidylethanolamine biosynthesis in human leukemic monocyte‐like U937 cells
Authors: Chu Arthur J. , Nguyen Camtu T.
Published: May 2005

The effect of ethanol (ETOH) on the incorporation of [14C]oleic acid (18:1) into lipid in human monocyte‐like U937 cells was investigated. With increasing time of exposure to ETOH, the percentage of the label distributed into neutral lipid (NL) declined from 35 per cent (3 h) to 10 per cent (24 h) accompanied by increased incorporation into phospholipid (PL). [14C] 18 : 1 was preferentially incorporated into triglyceride (TG) and phosphatidylcholine (PC), comprising over 65 per cent and 50 per cent of the label associated with NL and PL, respectively. Low concentrations of ETOH (⩽ 1·0 per cent; v/v) had no effect. At concentrations greater than 1·5 per cent, there was enhanced incorporation into TG and diacylglycerol (DAG) in a 24‐h incubation period, while at 16 h the label in phosphatidylethanolamine (PE) was decreased.

The effect of ETOH on the CDP‐choline or ethanolamine pathway was examined by monitoring the incorporation of [3H]choline or [14C]ethanolamine into PC or PE, respectively. At low concentrations ETOH had no effect on either choline uptake or the incorporation into PC. Higher concentrations (≥ 1·5 per cent) for 3 and 6 h resulted in a slightly decreased choline uptake, and the reduction (40–50 per cent) of incorporation into PC suggests that the CDP‐choline pathway was inhibited. There was a similar inhibition of the incorporation of [14C]ethanolamine into PE. When the cells were incubated for 3 h in the presence of 2 per cent ETOH and with labelled 18 : 1 and PL‐base, the ratios of incorporation (base/18 : 1) into PC and PE fractions decreased, indicating that the major inhibition lay in blockage of the availability of the base moiety for PL formation. Analysis of the distribution of the label into metabolites revealed that ETOH inhibited the conversion of [14C] ethanolamine into [14C]phosphorylethanolamine. The reduction in incorporation was not due to the enhanced breakdown of base‐labelled PL. Our results indicate that ETOH has an inhibitory effect on the CDP‐choline or ethanolamine pathway.
Effect of exogenous CDP‐choline on choline metabolism in isolated adult rat ventricular myocytes under normoxic and hypoxic conditions
Authors: Rabkin Simon W.
Published: May 2005

The purpose of this study was to examine the effect of exogenous CDP‐choline on choline metabolism and phosphatidylcholine biosynthesis in adult rat ventricular myocytes. Choline uptake and metabolism were examined, using [methyl3 H] choline. CDP‐choline in the medium produced a concentration dependent reduction in the amount of radio‐label in phosphocholine and phospholipid but it did not alter choline uptake into the myocytes. CDP‐choline also did not antagonize the effect of hypoxia on phosphatidylcholine synthesis; rather it accentuated the hypoxia‐induced reductions in cellular phosphocholine and phosphatidylcholine biosynthesis. These results indicate that the exogenous administration of CDP‐choline alters choline metabolism in the heart by reducing the formation of phosphocholine and phosphatidylcholine without altering choline uptake and suggest an effect of a CDP‐choline metabolite on choline metabolism which is not effective in opposing the effect of hypoxia on phosphatidylcholine biosynthesis.
Effect of cocaine and morphine on neutral endopeptidase activity of human peripheral blood mononuclear cells cultured with lectins
Authors: Leoni Lorenzo M. , Losa Gabriele A.
Published: May 2005

We have tested the effect of alkaloids (cocaine, morphine) and enkephalins on neutral endopeptidase of peripheral blood mononuclear cells activated by lectins. When treated with concanavalin A and cocaine, peripheral blood mononuclear cells showed an enhanced activity (+110 per cent) of the membrane neutral endopeptidase, which was not related to the expression of the common acute lymphoblastic leukemia antigen at the cell surface, although both molecules have the identical amino acid sequence. Phytohemagglutinin‐P, morphine and synthetic enkephalins did not induce the activity of neutral endopeptidase nor the expression of common acute lymphoblastic leukemia antigen. Our findings suggested that the drugs of abuse, cocaine and morphine, affected specific membrane constituents without altering proliferation, subcellular localization of membrane enzymes or the surface immune phenotype of peripheral blood mononuclear cells.
Thioglycollate stimulus modifies lymphocyte metabolism and proliferation. A comparison with lymphocyte activation by walker 256 tumour implantation
Authors: Rosa L. F. B. P. Costa , De Almeida A. F. , Safi D. A. , Curi R.
Published: May 2005

Key enzyme activities of glycolysis, the pentose‐phosphate pathway, the Krebs' cycle and glutaminolysis were measured in lymphocytes obtained from the control (CC), thioglycollate‐injected (TG) and Walker 256 tumour‐implanted (WT) groups, non‐immune and immune inflammatory stimuli, respectively. The rates of incorporation of [2‐14C]‐thymidine and [5‐3H]‐uridine into cultured lymphocytes were also determined. The results indicated that the rates of both [2‐14C]‐thymidine and [5‐3H]‐uridine incorporation were enhanced in lymphocytes obtained from thioglycollate‐injected (by an average of 80 per cent) and tumour‐implanted animals (by 2·4‐fold) as compared to control rats. Lymphocyte hexokinase activity diminished both in the TG (23 per cent) and WT (61 per cent) groups, whereas glucose 6‐phosphate dehydrogenase activity was not altered due to the non‐immune inflammatory stimulus, being reduced (23 per cent) in WT rats as compared to CC. The activity of lymphocyte citrate synthase was lowered by thioglycollate (39 per cent) and tumour‐implantation (46 per cent). In contrast, glutaminase activity was augmented in lymphocytes from the TG (41 per cent) and was not modified in the WT groups. Taken as a whole, the presence of the Walker 256 tumour did not affect the capacity for glutamine utilization but depressed glucose metabolism in these cells. On the other hand, the non‐immune inflammatory stimulus suppressed the activities of glycolysis and the Krebs' cycle and enhanced that of glutaminolysis in lymphocytes.
Induction of differentiation by radiation and hyperthermia in neuroblastoma—glioma hybrid cells
Authors: Sugihara Masaki , Fujita Yasuhiko , Enomoto Koh‐Ichi , Maeno Takashi , Ishida Tetsuya
Published: May 2005

The effects of either radiation or hyperthermia on the differentiation potential of NG108‐15, a neuroblastoma‐glioma hybrid cell line, were studied. After radiation and hyperthermia, the outgrowth of neurites from NG108‐15 cells was potentiated, and polarizing current and voltage pulses induced a distinct action potential and a diphasic (inward following outward) current, respectively. An increase in the specific activity of acetylcholinesterase was also observed. In addition, both treatments induced an elevation of the concentration of intracellular calcium in some cells. The increase in intracellular calcium concentration caused by applying the calcium ionophore, A23187, induced differentiation. It is suggested that both the radiation‐ and the hyperthermia‐induced increases of electrical excitability and acetylcholinesterase activity may have originated from an increase in intracellular Ca2+ concentration.
Characterization of plasma membrane redox activity from ehrlich cells
Authors: Del Castillo‐Olivares Antonio , Márquez Javier , De Castro Ignacio Núñez , Medina Miguel Angel
Published: May 2005

Ferricyanide reductase activity of plasma membranes isolated from Ehrlich ascites tumour cells was very sensitive to trypsin treatment. The decreases of activity observed after treatment with different glycosidases suggests that ferricyanide reductase is a glycoprotein. The opposite effects of phospholipase A2 and phospholipase C on the redox activity indicate that the phospholipidic environment plays an important role in the function of ferricyanide reductase. Sodium ions at millimolar concentrations, and some divalent cations at micromolar concentrations (Ca2+, Mg2+, Sr2+, and Mn2+) behaved as stimulators of ferricyanide reductase activity.
Inositol lipid phosphorylation and breakdown in rat liver nuclei is affected by hydrocortisone blood levels
Authors: Santi Patrizia , Marmiroli S. , Falcieri E. , Bertagnolo V. , Capitani S.
Published: May 2005

The possibility that inositol lipid metabolism is related to nuclear events accompanying steroid hormone action has been investigated by comparing lipid phosphorylation and breakdown in normal rat liver nuclei and in hypo‐ and hypercortisolemic conditions. Lipid phosphorylation in vitro showed the presence of diacylglycerol (DAG)‐, phosphatidylinositol (PI)‐ and phosphatidylinositol‐4‐phosphate (PIP)‐kinase activity, with differences between total tissue homogenates and isolated nuclei, relevant to the treatment in vivo. Administration of hydrocortisone (HC) produced a marked decrease in the phosphorylated nuclear products without influencing the homogenate kinase activity. Under conditions which were optimal for the kinase activities, nuclear PIP‐kinase was strongly increased in presence of a high blood level of HC whereas PI‐kinase activity was reduced. From these observations it appears that the observed differences were due to specific modulation of kinase activities rather than to changes in the availability of substrates.

The phosphoinositide‐specific phospholipase C (PLC) activity was also investigated. In the presence of a high HC blood level, the phosphodiesteratic cleavage of PIP strongly increased, while that of phosphatidylinositol bisphosphate (PIP2) was similar in normal and hypercortisolemic conditions. Nuclear phosphoinositide hydrolysis was affected by PLC, β and γ isoforms, which were equally represented in all the conditions investigated, indicating that the observed changes of activity were due to a modulation rather than to a change in the amount of enzyme.

These results suggest that inositol lipid metabolism plays a role in the nuclear modifications accompanying steroid hormone induction of transcriptional activity.
Kinetics of the inhibition of acetylcholinesterase from pigeon brain by procaine hydrochloride
Authors: Al‐Jafari Abdulaziz A. , Duhaiman Ali S.
Published: May 2005

The kinetic parameters of the inhibition of pigeon brain acetylchlolinesterase (AChE) by procaine hydrochloride were investigated. Procaine (0·083–1·67 mM) reversibly inhibited AChE activity (15–83 percent) in a concentration dependent manner, the IC50 being about 0·38 mM. The Michaelis‐Menten constant (Km) for the hydrolysis of acetylthiocholine iodide was found to be 1·53 × 10−4 M and the Vmax was 1·06 μmol min−1 mg−1 protein. Dixon as well as Lineweaver‐Burk plots and their secondary replots indicated that the nature of the inhibition is of the linear mixed type which is considered to be a mixture of partial competitive and pure non‐competitive. The values of Ki(slope) and Ki (intercepts) were estimated as 0·14 mM and 0·22 mM respectively by the primary Dixon and by the secondary replots of the Lineweaver‐Burk plot. The Ki′/Ki ratio shows that procaine has a greater affinity of binding for the peripheral than for the active site.
Red blood cell phagocytosis following hexokinase inactivation
Authors: Chiarantini L. , Antonelli A. , Rossi L. , Fraternale A. , Magnani M.
Published: May 2005

Hexokinase inactivating antibodies were loaded into human erythrocytes using an encapsulation procedure based on hypotonic haemolysis, isotonic resealing and reannealing. Red blood cells loaded with anti‐hexokinase IgG showed 20 percent residual hexokinase activity and reduced glycolytic activity. 9Incubation of these cells in the presence of an oxidizing agent such as terbutyl hydroperoxide (TBH) and then in autologous plasma, promoted opsonization by autologous IgG and complement deposition, but not haemolysis. Furthermore, the antihexokinase IgG loaded cells treated with TBH were actively recognized and phagocytosed by macrophages. Thus, metabolic impairment of human erthrocytes promotes autologous IgG binding, C3 deposition and phagocytosis, a mechanism already reported for the removal of senescent erythrocytes.
A calcium‐dependent protein kinase is present in tetrahymena
Authors: Hegyesi Hargita , Csaba G.
Published: May 2005

A Ca2+‐dependent protein kinase of Tetrahymena thermophila has been partially purified and characterized. The molecular mass of the enzyme is less than that of similar enzymes (for example protein kinase C), being about 55 kDa. After purification and in the presence of Ca2+ the enzyme activity increased. The promoter of protein kinase C (PKC) activity, phorbol myristate acetate (PMA), increased the activity while the protein kinase inhibitor H‐7 decreased the activity of the enzyme. The experiments demonstrate the presence, activity and similarity to vertebrate enzymes of a protein kinase at a low level of phylogeny.
Time‐dependent irreversible inhibition of bovine kidney alkaline phosphatase by oxidized adenosine. Use of this compound as a site‐directed inhibitor for studying uncompetitive inhibition
Authors: Butterworth Peter J.
Published: May 2005

The L/B/K type of mammalian alkaline phosphatase (ALP) is inhibited uncompetitively by nucleotides. A combination of adenosine and nicotinamide is more effective than either adenosine or nicotinamide alone, probably because a dinucleotide structure is necessary to trigger a conformational change accompanying binding of structures such as NADH. It has been suggested that a loop region containing residue 429 in the ALP polypeptide is important in the interaction of uncompetitive inhibitors with the enzyme. In the L/B/K isoenzyme, residue 429 is a histidine and is a potential target for modification. In an attempt to learn more about the molecular events accompanying inhibition of ALP by uncompetitive inhibitors, bovine kidney ALP was reacted with oxidized adenosine in the presence of nicotinamide to see if site‐directed modification occurs. Kidney ALP was irreversibly inactivated by oxidized adenosine but the reaction was slow. The site modified is likely to be close to the region of binding. Sequence data for the kidney enzyme shows that in the region of residue 429 there are no residues except His429 itself that is likely to react with oxidized adenosine.
Differential expression of nuclear HMG1, HMG2 proteins and H10 histone in various blood cells
Authors: Čabart Pavel , Kalousek Ivan , Jandová Danuše , Hrkal Zbyněk
Published: May 2005

Changes in the levels of chromosomal high‐mobility group proteins HMG1, HMG2 and histone H10 were investigated in blood cells of various types, proliferation activity and stage of differentiation. The relative amounts of proteins HMG1, HMG2 and histone H10 were evaluated densitometrically by SDS‐PAGE of 5 per cent w/v perchloric acid extracts of blood cells. Concerning the HMG1 and HMG2, the main conclusions were: the expression of these HMG proteins was higher in malignant cells, namely leukemia cell lines, then in lymphocytes or granulocytes and the distribution of HMG1 and HMG2 was highly cell‐specific. In comparison with lymphoid cells, the levels of HMG1/2 were higher in myeloid cells. The results revealed that in myeloid cells HMG2 prevails over HMG1. There was no direct correlation between HMG1/2 expression and proliferation activity. The levels of HMG1/2 did not depend on the transcription of chromatin either. However, there was some connection between irreversibly differentiated nonproliferating cells and a loss of HMG1/2 proteins. Reversibly differentiated leukemic cells retain their HMG1/2 levels. Similarly to HMG1/2, H10 showed a strong cell specificity. The level of H10 was different in the various blood cell types. As compared with lymphoid cells, the level of H10 was several‐fold higher in myeloid cells, regardless of whether they were normal or malignant. Moreover, there was an accumulation of H10 in differentiating HL‐60 cells accompanied by only a slight decline in cell proliferation; this agrees with the idea that H10 expression is not directly associated with the inhibition of cell growth. Rather higher expression of H10 is related to changes during cell differentiation.
Effect of lipoproteins on macrophage superoxide generation
Authors: Mohan Pamarthi F. , Jacobson Marc S.
Published: May 2005

Superoxide production by macrophages and leukocytes may have an important role in atherogenesis. Whether lipoproteins modulate the superoxide production of these cells is not clear. Therefore, the effect of lipoproteins on the production of superoxide by rat peritoneal macrophages was tested. VLDL and LDL inhibited digitonin‐stimulated superoxide production in a dose‐dependent manner. Maximum inhibition was observed at 10 μg ml−1 of VLDL protein and 50 μg ml−1 of LDL protein respectively. In contrast, HDL (40 μg protein ml−1) enhanced digitoninstimulated superoxide production (by 47 per cent). Macrophage superoxide production induced by arachidonic acid was enhanced by both VLDL (130 per cent) and HDL (84 per cent), whereas LDL had no effect. The lipoproteins had no effect on macrophage superoxide stimulated by other agonists such as phorbol myristate 13‐acetate, sodium fluoride or the calcium ionophore, A23187. The effect of lipoproteins was also tested on human polymorphonuclear leukocyte superoxide generation, stimulated by digitonin and PMA. Ten μg of VLDL, 50 μg of LDL and 50 μg of HDL proteins ml−1, inhibited digitonin‐induced superoxide production by 50, 100 and 33 per cent respectively. Lipoproteins had no effect on PMA stimulated superoxide generation by human polymorphonuclear leukocytes. The stimulatory and inhibitory effects of lipoproteins on macrophage and neutrophil superoxide generation could be important in the understanding of oxidation‐mediated development of atherosclerosis.