Biomedical subjects

A Takashima

Publications and source records attributed to A Takashima.

209 records · Page 12Linked to original sources

PubMedDate not supplied

Vasoactive intestinal peptide (VIP) causes memory impairment in passive avoidance responding of the rat.

Our previous studies demonstrated that CCK-8 and its analog, cerulein (CER), have a potent preventive action on experimental amnesia, and that VIP has reciprocal action against CCK-8 and CER. Since VIP has been reported to cause amnesia, we carried out the present experiments to confirm this action and to examine the preventive effect of CER on VIP-induced amnesia. In the passive avoidance response, central administration, but not peripheral injection, of VIP caused amnesia; the effective portion of the molecule was found to be located in the N-terminus amino acid sequence. Secretin and PACAP, which have similar molecular structures to that of VIP, had no amnestic action. Preadministration of CER prevented VIP-induced memory deficit. The VIP antagonists did not affect amnesia induced by electroconvulsive shock and scopolamine. It was concluded that CER prevents VIP-induced memory deficit in the passive avoidance response of the rat.

Animals↗

PubMedDate not supplied

Influence of chronic intracerebroventricular infusion of vasoactive intestinal peptide (VIP) on memory processes in Morris water pool test in the rat.

In our previous study, bolus injection of VIP into the lateral cerebral ventricle, at nonphysiological high doses, has been shown to produce amnesia. Accordingly, in the present study, VIP was infused chronically into the cerebral ventricle of the rat at a rate of 10 ng per day for 2 weeks. During the infusion period, the animals were subjected to the Morris water pool test. The VIP infusion caused an apparent impairment of memory, particularly in the acquisition of new information; VIP(1-12) also caused similar impairment, but to a lesser extent. The VIP antagonists did not affect the performance of learned tasks. However, cerulein treatment prevented the VIP-induced memory impairment.

Animals↗

PubMedDate not supplied

Two factors of experienced deficits in schizophrenia and their relationships with positive, negative, and depressive symptoms.

Eighty inpatients and 20 outpatients with ICD-10 schizophrenia were assessed with the Manchester Scale (MS) and the scale for the assessment of Subjective Experience of Deficits in Schizophrenia (SEDS). A factor analysis on MS scores yielded a three-factor solution: negative symptoms, positive symptoms, and anxious-depressive factor. On the other hand, a factor analysis on SEDS scores provided a seven-factor solution. The first factor, "awareness of social incompetence (ASI)," positively correlated with the anxious-depressive factor. ASI may reflect a negative cognitive attitude of persons who easily become depressive. The second factor, "subjective cognitive disturbance (SCD)," positively correlated with the positive-symptoms factor. SCD might represent a subtle disturbance, which can also produce positive symptoms. We found no factor on SEDS that correlated with the negative-symptoms factor. It was noted that a selection and comparison of items and the cultural background of subjects should be considered.

Adolescent↗

PubMedDate not supplied

Possible role of tau protein kinases in pathogenesis of Alzheimer's disease.

Tau protein kinases (TPK) I and II were isolated as candidate enzymes responsible for the hyperphosphorylation observed in PHF-tau. Four phosphorylation sites of tau were identified for each kinase, accounting for most, but not all, of the major phosphorylation sites of PHF-tau. Immunostaining with anti-TPKI antibody indicated that this kinase is up-regulated in AD brain. Such up-regulation of TPKI and phosphorylatioin of tau were reproduced by treating cultured hippocampal cells with amyloid beta (Abeta) protein. In addition, we found that TPKI can phosphorylate and inactivate pyruvate dehydrogenase (PDH), which is expected to result in depletion of acetyl-CoA, a key substrate of acetyl choline synthesis. Indeed, when septum cells were treated with Abeta, the level of acetyl choline decreased dramatically.

Alzheimer Disease↗

PubMedDate not supplied

Information processing by nonspiking interneurons: passive and active properties of dendritic membrane determine synaptic integration.

Nonspiking interneurons control activities of postsynaptic cells without generating action potentials in the central nervous system of many invertebrates. Physiological characteristics of their dendritic membrane have been analyzed in previous studies using single electrode current- and voltage-clamp techniques. We constructed a single compartment model of an identified nonspiking interneuron of crayfish. Experimental results allowed us to simulate how the passive and active properties of the dendritic membrane influence the integrative processing of synaptic inputs. The results showed that not only the peak amplitude but also the time course of synaptic potentials were dependent on the membrane potential level at which the synaptic activity was evoked. When the synaptic input came sequentially, each individual input was still discernible at depolarized levels at which the membrane time constant was short due to depolarization-dependent membrane conductances. In contrast, synaptic potentials merged with each other to develop a sustained potential at hyperpolarized levels where the membrane behaved passively. Thus, synaptic integration in a single nonspiking interneuron depends on the value of membrane potential at which it occurs. This probably reflects the temporal resolution required for specific types of information processing.

Action Potentials↗

PubMedDate not supplied

Electrophysiological and theoretical analysis of depolarization-dependent outward currents in the dendritic membrane of an identified nonspiking interneuron in crayfish.

Depolarization-dependent outward currents were analyzed using the single-electrode voltage clamp technique in the dendritic membrane of an identified nonspiking interneuron (LDS interneuron) in situ in the terminal abdominal ganglion of crayfish. When the membrane was depolarized by more than 20 mV from the resting potential (65.0 +/- 5.7 mV), a transient outward current was observed to be followed by a sustained outward current. Pharmacological experiments revealed that these outward currents were composed of 3 distinct components. A sustained component (I(s)) was activated slowly (half rise time > 5 msec) and blocked by 20 mM TEA. A transient component (I(t1)) that was activated and inactivated very rapidly (peak time < 2.5 msec, half decay time < 1.2 msec) was also blocked by 20 mM TEA. Another transient component (I(t2)) was blocked by 100 microM 4AP, activated rapidly (peak time < 10.0 msec) and inactivated slowly (half decay time > 131.8 msec). Two-step pulse experiments have revealed that both sustained and transient components are not inactivated at the resting potential: the half-maximal inactivation was attained at -21.0 mV in I(t1), and -38.0 mV in I(t2). I(s) showed no noticeable inactivation. When the membrane was initially held at the resting potential level and clamped to varying potential levels, the half-maximal activation was attained at -36.0 mV in I(s), -31.0 mV in I(t1) and -40.0 mV in I(t2). The activation and inactivation time constants were both voltage dependent. A mathematical model of the LDS interneuron was constructed based on the present electrophysiological records to simulate the dynamic interaction of outward currents during membrane depolarization. The results suggest that those membrane conductances found in this study underlie the outward rectification of the interneuron membrane as well as depolarization-dependent shaping of the excitatory synaptic potential observed in current-clamp experiments.

4-Aminopyridine↗

PubMedDate not supplied

Regulation of T-cell receptor gamma-chain RNA expression in murine Thy-1+ dendritic epidermal cells.

The epidermis of normal mice contains two distinct populations of dendritic cells derived from the bone marrow, Ia+ Langerhans cells and Ia- cells that express the Thy-1 alloantigen. The Thy-1-bearing dendritic epidermal cells (Thy-1+ dEC) have a surface phenotype similar to that of very early T-lineage cells, produce IL-2-like growth factors and exhibit cytotoxicity which is not restricted by the major histocompatibility complex (MHC). The relationship of Thy-1+ dEC to the T-cell lineage is unclear. Most T lymphocytes bear a receptor for antigen composed of an alpha chain and a beta chain associated with a nonpolymorphic complex termed CD3 (T3). A minor population carries a receptor in which CD3 is associated with a gamma/delta complex. We have analysed clones of Thy-1+ dEC for rearrangement and expression of the genes for the alpha-, beta- and gamma-chains of the T-cell receptor (TCR). They do not express alpha or beta but do carry a gamma/delta complex. Activation of the cells with Con A is associated with a rapid decrease in the steady-state level of gamma-chain RNA. Because Thy-1+ dEC resemble early stage T lymphocytes, down-regulation of TCR expression may reflect a necessary event during T cell differentiation.

Animals↗

PubMedDate not supplied

Photocarcinogenesis.

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Animals↗

PubMedDate not supplied

Binding of anti-inflammatory alpha-melanocyte-stimulating-hormone peptides and proinflammatory cytokines to receptors on melanoma cells.

alpha-Melanocyte-stimulating hormone (alpha-MSH1-13), a peptide derived from proopiomelanocortin, has remarkable anti-inflammatory and antipyretic activities. This peptide and a tripeptide that forms the COOH-terminal portion of the molecule (alpha-MSH11-13; Lys Pro Val) inhibit inflammation when given centrally or peripherally. Because of the similarity in their actions, the tripeptide has been presumed to be the amino acid message sequence underlying the effects of alpha-MSH1-13. To test the possibility that the two peptides occupy the same receptors, competitive binding experiments were performed with B16 mouse melanoma cells that are known to have alpha-MSH1-13 receptors. In these experiments, alpha-MSH11-13 did not inhibit binding of a radiolabelled alpha-MSH1-13 analog. This finding suggests that alpha-MSH1-13 and alpha-MSH11-13 exert their anti-inflammatory/antipyretic/anticytokine effects via stimulation of separate receptors. Because alpha-MSH inhibits the effects of several cytokines including inflammation caused by interleukin (IL)-6 and IL-8, the capacity of these cytokines to compete for alpha-MSH binding sites was tested. There was no evidence that these proinflammatory cytokines bind to alpha-MSH receptors on murine melanoma cells. Although further tests with host cells involved in inflammation are required, the latter result is the first evidence that the mechanism of anticytokine action of alpha-MSH does not depend upon peptide/cytokine competition for binding sites.

Amino Acid Sequence↗

PubMedDate not supplied

A survey regarding the disclosure of the diagnosis of cancer in Toyama Prefecture, Japan.

A survey regarding the revelation of the diagnosis of cancer to patients was conducted on 116 medical doctors (MD), 206 paramedical personnel (PP) and 789 lay persons (LP) in June 1989 in Toyama prefecture, Japan. When asked in the case that their parents or spouse had cancer, only 29.8% of all respondents answered that they would reveal the diagnosis of cancer to their family member. On the contrary, if they themselves had cancer, 56.3% of all respondents answered that they wished the diagnosis to be revealed, and 77.4% of these answered that they wished to be informed of the cancer diagnosis by the doctor in charge. They wanted to know the details of their condition from their medical doctor, and thought that they could receive this knowledge calmly. Thirty-one percent (34/108) of the doctors questioned reveal the diagnosis of cancer to their patients and 79.4% of these answered that they felt that telling the true diagnosis was good. A serious responsibility for the medical doctor was indicated.

Adult↗

PubMedDate not supplied

Clinical analysis of cancer patients with bacteremia for the past ten years (1982-1991).

A trend in bacteremia associated with malignancies was studied in 159 cancer patients (pts) over the past ten years (1982-1991) in our university hospital. The proportion of female, aged persons and patients from the Int Med Dept had a tendency to increase in the later 5 years compared to the former 5 years. There was no significant change in proportion among G (+), G (-) and fungus groups. However, St. aureus has a tendency to increase among G (+) bacteria and Ps. aeruginosa among G (-) bacteria. The clinical features of the cancer patients with bacteremia were different depending on the types of organisms or kinds of underlying malignancies.

Adult↗