Blueberry flavonoids inhibit matrix metalloproteinase activity in DU145 human prostate cancer cells.

Regulation of the matrix metalloproteinases (MMPs), the major mediators of extracellular matrix (ECM) degradation, is crucial to regulate ECM proteolysis, which is important in metastasis. This study examined the effects of 3 flavonoid-enriched fractions (a crude fraction, an anthocyanin-enriched fraction, and a proanthocyanidin-enriched fraction), which were prepared from lowbush blueberries (Vaccinium angustifolium), on MMP activity in DU145 human prostate cancer cells in vitro. Using gelatin gel electrophoresis, MMP activity was evaluated from cells after 24-hr exposure to blueberry fractions. All fractions elicited an ability to decrease the activity of MMP-2 and MMP-9. Of the fractions tested, the proanthocyanidin-enriched fraction was found to be the most effective at inhibiting MMP activity in these cells. No induction of either necrotic or apoptotic cell death was noted in these cells in response to treatment with the blueberry fractions. These findings indicate that flavonoids from blueberry possess the ability to effectively decrease MMP activity, which may decrease overall ECM degradation. This ability may be important in controlling tumor metastasis formation.     

Atp-activated ionic permeability in smooth muscle cells isolated from the guinea pig urinary bladder

Smooth muscle cells from the guinea pig urinary bladder were investigated by voltage clamping at the plasma membrane and using an intracellular perfusion technique. Applying adenosine triphosphate (ATP) at a concentration greater than 3 × 10^–8 M and at a membrane potential of –100 to –30 mV produced a rise in fast inward transmembrane current. A similar effect was exerted by adenosine diphosphate (ADP) and -, -, and ,-methylene ATP. Application of guanosine triphosphate, inosine triphosphate, adenosine monophosphate (AMP), and adenosine failed to activate this current. It was found that AMP blocks ATP receptors competitively. No pharmacological differences were found between the latter ATP receptors and those of rat sensory neurons. The ATP receptors were rapidly desensitized and recovered their sensitivity to agonists extremely slowly. Speed of desensitization was reduced by a decrease in ATP concentration.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 19, No. 1, pp. 95–100, January–February, 1987.     

Monosynaptic pathway responsible for generation of bursting activity in theHelix pomatia RPal neuron

The connection between a visceral ganglia interneuron initiating bursting pacemaker activity in the RPal neuron and the RPal neuron itself was investigated inHelix pomatia. Stimulating the interneuron either initiated or intensified bursting activity in the RPal neuron, depending on initial electrical activity in this cell. Replacing calcium with magnesium ions in the extracellular fluid and adding CdCl₂ to this fluid reversibly inhibited the effect of interneuronal stimulation on the RPal neuron. The latter effect was unaffected by increasing the concentration of extracellular Ca²⁺ 10 to 70 mM. Intracellular injection of both Cs⁺ and TEA into the interneuron produced an increase in the duration of its action potentials and rendered the link connecting the neurons more effective. It is deduced that a monosynaptic chemical connection exists between the interneuron and the RPal neuron for which a peptide compound serves as transmitter.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 19, No. 1, pp. 20–28, January–February, 1987.     

Influence of food motivation on neuronal response of the cat somatic cortex during instrumental reflex

Spike activity in neurons of areas 3 and 4 was investigated in experiments on cats during the conditioned reflex response of placing the paw on a support both before and after feeding ad libitum. Ingestion of a feed consisting of a rapidly absorbed glucose dairy mix did not prevent the reflex taking place if the animals' favorite food was used as reinforcement. Background activity increased in two-thirds of the neurons after the feed; the tonic constituent of neuronal response declined substantially and repeated contraction of the biceps occurring at the same rate as locomotor movements disappeared. Difference in latency of response produced by the conditioned stimulus in the same neurons before and after feeding measured 50–300 msec during the experiment. Measurements of latency of placing motion remained largely unchanged. Changes in the latency of neuronal spike response were thus found to be interrelated with the intensity of the animal's motivational excitation. It is suggested that fluctuations in degree of food motivation lead to changes in cortico-subcortical relationships responsible for initiation and performance of conditioned movements in these animals.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 19, No. 5, pp. 646–653, September–October, 1987.     

L-glutamate activated membrane conductivity in spinal cord neurons during early chick embryogenesis

Transient and steady-state components of L-glutamate-activated membrane currents were investigated using intracellular perfusion, voltage clamp, and concentration clamp techniques in spinal cord neurons of 6–11 day chick embryos. Hill's coefficient was found to equal 1 for transient and 2 for steady-state components. It was shown that the L-glutamate-activated receptors are present, which appear in the membrane of spinal neurons at the early stages of development.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 19, No. 2, pp. 251–258, March–April, 1987.     

Beta-adrenergic agonists and cyclic AMP decrease intracellular resting free-calcium concentration in ileum smooth muscle

Intracellular free-calcium levels were measured in strips of longitudinal smooth muscle from guinea-pig ileum; fura-2 was used as a calcium monitor. At rest the calcium concentration was about 180 nM, and this rose to 300-400 nM following electrical stimulation and during spontaneous calcium transients (all measurements at 23-25 degrees C). Isoprenaline suppressed the spontaneous calcium transients, and reduced the resting calcium level to about 130 nM. This fall in resting calcium concentration was seen even in muscle strips which did not have spontaneous activity. Elevation of intracellular cyclic AMP levels, produced by forskolin or dibutyryl cyclic AMP, mimicked the actions of isoprenaline. We conclude that the relaxant effects of beta-adrenergic agonists of visceral smooth muscle may be explained partly by a fall in intracellular resting free-calcium level, mediated via an increase in cyclic AMP.     

Human lymphoblastoid cell lines secreting antibodies with restricted HLA specificity

Peripheral B lymphocytes obtained from three healthy individuals who had been immunized against peripheral blood lymphocytes from appropriate HLA-incompatible donors were transformed by the use of Epstein-Barr virus. The transformed blastoid B cells were repeatedly subcultured by means of cluster picking, and the HLA antibody-producing cultures were identified by testing the culture supernatants by means of the cytotoxicity assay, using the corresponding donor cells. Thus far, four cell lines that secrete cytotoxic HLA antibodies (MP1, 3, 4, and 5) have been established. Specific immunoabsorption experiments revealed that the antibody activity is carried by lambda-type IgM for MP1, by kappa-type IgM for MP3 and MP5, and by both for MP4. Specificity analysis of a panel of HLA-pretyped cells indicated that MP1 detects DQw2, whereas MP5 recognizes B7. The specificity of MP3 was similar to a DQ specificity termed DC5 (probably equivalent to TA10) but not the same. In the case of MP4, both of the lambda-type and kappa-type antibodies appeared to be directed toward new HLA class 11 determinants.Abbreviations used in this paper HLA human major histocompatibility - EBV Epstein-Barr virus - B-LCL Blymphoblastoid cell line - NA not absorbed - PBS phosphate-buffered saline - SPA Sepharose protein A - NRS normal rabbit serum     

Structure of a protein catalyzing the formation of 11 cis-retinal in the visual cycle of invertebrate eyes

A pigment made up of a protein able to bind retinal as well as retinol is described. The molecule consists of a dimer with a molecular weight of 50,000 which binds one molecule of retinal. The binding site for retinal is a Schiff base buried in the interior of the protein. Retinol is probably bound to the protein in the same site as for retinal, although not covalently, as suggested by the absorbance spectra. The protein, extracted from honeybee retina, is involved in visual pigment metabolism, and its structure may elucidate the mechanism of the stereospecific photoisomerization of all trans-retinal to 11-cis-retinal.     

The role of the cytosolic fraction and of initiation factor eIF-2 for changes of the rate of protein synthesis during liver regeneration

The protein synthesis-stimulating activity of the cytosolic fraction from regenerating rat liver was tested in a cell-free system using washed polysomes from normal rat liver. This activity undergoes significant changes during liver regeneration after partial hepatectomy (p.h.). An initial decrease until 16 h after p.h. is followed by a significant increase until 24 h after p.h. Beyond 32 h after p.h. the activity begins to decline again. Evidence is presented that these changes of the cytosolic activity may not be due to alterations in the distribution of protein synthesis-stimulating factors between the microsomal and the cytosolic fraction. The Met-tRNAf-binding activity of the cytosolic fraction changes during liver regeneration analogously to the protein synthesis-stimulating activity measured in the polysomal assay. This indicates that initiation factor eIF-2 is involved in the observed changes of the cytosolic activity. This conclusion could be confirmed by addition of purified eIF-2 to the polysomal assay system. Addition of eIF-2 to cytosolic fractions of low endogenous protein synthesis-stimulating activity (16 h after p.h.) enhances amino-acid incorporation to a significantly higher extent than addition to highly active cytosolic fractions (24 h and 32 h after p.h.). From these results it is concluded that changes in eIF-2 plays an essential role in the described alterations of the cytosolic activities during liver regeneration.