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J Kopp

Publications and source records attributed to J Kopp.

At least 73 records · Page 4Linked to original sources
PubMed1994

Distribution of D1- and D2-dopamine receptors, and dopamine and its metabolites in the human brain.

Densities and distribution of D1-dopamine and D2-dopamine receptors were investigated in vitro using [3H]SCH 23390 and [3H]raclopride in receptor binding assays and autoradiography on human post mortem whole hemisphere slices to serve as anatomical correlates to PET studies using [11C]SCH 23390 and [11C]raclopride. In addition, the levels of dopamine and its metabolites were determined by HPLC in various brain regions. Both dopamine receptor subtypes, as well as dopamine, HVA and DOPAC, were primarily found in the basal ganglia. Very high densities of D1-dopamine receptors were found particularly in the medial caudate nucleus, whereas D2-dopamine receptors were evenly distributed throughout the caudate. The densities of D1- and D2-dopamine receptors were similar in the caudate nucleus and the putamen, whereas there were 4 to 7 times higher densities of the D1- than of the D2-dopamine receptors in several limbic and neocortical regions. The receptor distribution in the autoradiographic study was consistent with that demonstrated in the living human brain using [11C]SCH 23390 and [11C]raclopride.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1994

Expression of mRNAs encoding ARPP-16/19, ARPP-21, and DARPP-32 in human brain tissue.

In this study we have isolated and sequenced human cDNAs for the phosphoproteins DARPP-32, ARPP-21, and ARPP-16/19, and have compared these sequences to previously characterized bovine and rat cDNAs. In situ hybridization and Northern blot analysis with the human cDNA probes were used to study the expression of mRNAs encoding ARPP-16/19, ARPP-21, and DARPP-32 in human postmortem brain tissue. In situ hybridization was performed using horizontal whole hemisphere sections. Five representative levels of the brain ranging from 71 mm to 104 mm ventral to vertex were examined. All three probes showed distinct hybridization patterns in the caudate nucleus, putamen, nucleus accumbens, and the amygdaloid complex. For ARPP-16/19 mRNA, a hybridization signal comparable to the signal in caudate nucleus, putamen, and nucleus accumbens was also detected in the neocortex. ARPP-21 and DARPP-32 mRNA, on the other hand, were present in lower levels in neocortical regions. DARPP-32 mRNA was abundant in the cerebellar cortex at the level of the Purkinje cell layer. High levels of ARPP-16/19 and ARPP-21 mRNA were also found in the cerebellar cortex, where they were confined to deeper layers. The present result demonstrate that mRNAs for the three phosphoproteins are expressed in overlapping, but also distinct, areas of the human brain that in many cases coincide with previously described distribution of the dopamine D1 receptor.

Aged↗
PubMed1993

[Sensitivity of immunoscintigraphy in malignant melanoma of the choroid].

Between June, 1988 and May, 1991 30 patients with clinically suspected malignant melanoma were examined in succession by means of immunoscintigraphy and the 225.28 S antibody (tagged with Tc-99m). Retrospectively, the results showed a sensitivity of over 70% by SPECT examination. Positive accumulation of the antibody within the suspected melanoma gives reason to believe that this degree of accuracy can be improved by comparative application of unspecific, radioactively tagged proteins. In the absence of accumulation within clinically, and in particular echographically, confirmed malignant melanoma treatment should be performed.

Adult↗
PubMed1992

Effect of raclopride on dopamine D2 receptor mRNA expression in rat brain.

Prolonged treatment with dopamine D2 receptor antagonists is known to elevate the density of dopamine D2 receptor binding sites in caudate-putamen and nucleus accumbens in rat and human brain. In this study we used the dopamine D2 receptor antagonist raclopride (3 mumol/kg, s.c.) to determine if a single injection or daily administration of this drug for up to 18 days changed the expression of dopamine D2 receptor mRNA in rat caudate-putamen and accumbens as measured by in situ hybridization. A single injection of raclopride did not significantly change the numerical density of dopamine D2 receptor mRNA-expressing neurons in any of the regions examined. A daily administration of raclopride for 18 days resulted in a 31% increase in the number of cells expressing detectable amounts of dopamine D2 receptor mRNA in dorsolateral caudate-putamen and in a 20% increase in the area of silver grains over individual hybridization-positive neurons in this brain region measured on emulsion-dipped slides. The region-specific increase in the D2 receptor mRNA level in dorsolateral caudate-putamen was confirmed by measurement of the hybridization signal on X-ray film autoradiograms. The levels of D2 receptor mRNA remained unchanged in medial caudate-putamen and accumbens after 18 days' treatment. The region-selective increase in dopamine D2 receptor mRNA expression in dorsolateral caudate-putamen indicates a differential regulation of dopamine D2 receptor mRNA expression in a subpopulation of caudate-putamen neurons by this neuroleptic. We suggest that the increase in dopamine D2 receptor density in caudate-putamen known to follow prolonged dopamine D2 receptor blockade to some extent is regulated at the level of gene expression.

Analysis of Variance↗
PubMed1992

The HIV-1 surface protein gp120 has no effect on transmembrane signal transduction in T cells.

The ability of HIV-1 envelope glycoprotein gp120 to induce transmembrane signaling processes in human T cells and tumor T-cell lines was investigated. Differently glycosylated gp120 preparations were characterized with respect to their purity, the fraction of native gp120, and the affinity of the gp120-CD4 interaction. These data were used to establish experimental conditions that allow a substantial fraction of the CD4 receptor to be complexed with gp120 in the course of the experiments. The results are in contrast to several previous studies since no effect of gp120 on the intracellular Ca2+ concentration, the metabolism of inositol phosphates and arachidonic acid, protein kinase C translocation, and tyrosine phosphorylation was found. Cross-linking of the gp120:CD4 complex by anti-gp120 antibodies did not elicit additional effects.

Arachidonic Acids↗
PubMed1992

Psychosocial correlates of diabetes and renal dysfunction.

Psychosocial issues related to diabetes and renal dysfunction are complicated and many times misunderstood. Building relationships and acquiring relevant information from patients will help patients adjust to disease complications and enhance compliance.

Chronic Disease↗
PubMed1992

[Radiation exposure during defecography].

The introduction of a new radiological method requires the assessment of the advantage-risk ratio. On measuring the radiation doses during defecography, skin entrance and gonadal exposure values were found to be lower than during well-known and well-established examinations of the small pelvis, such as colon enema and CT of the lower abdomen. Defecography, as a radiological tool for diagnosing the anorectal function is, therefore, also suitable for young persons.

Defecation↗
PubMed1991

Distribution of cholecystokinin mRNA and peptides in the human brain.

Expression of preprocholecystokinin mRNA was studied in regions of post mortem human brain using RNA blot analysis (Northern blot) and in situ hybridization. Northern blot analysis using a cDNA probe showed high levels of an approximately 0.8 kb preprocholecystokinin mRNA in all regions of neocortex examined. Lower levels of preprocholecystokinin mRNA were detected in amygdaloid body and thalamus. In situ hybridization analysis using the same cDNA probe revealed numerous weakly labelled neurons in different areas of human neocortex and less numerous neurons in hippocampus and amygdaloid body. High-performance liquid-chromatography and gel-chromatography combined with radioimmunoassay of cholecystokinin-like immunoreactivity from human cerebral cortex and caudate nucleus revealed two major forms, one coeluting with sulphated cholecystokinin-8 and the other coeluting with sulphated cholecystokinin-58. Two minor components coeluting with cholecystokinin-4 and cholecystokinin-5 were also detected. The finding of cholecystokinin-like immunoreactivity corresponding to cholecystokinin-8 and cholecystokinin-58 in caudate nucleus where no preprocholecystokinin mRNA was found, indicates the presence of these peptides in afferent nerve terminals.

Blotting, Northern↗
PubMed1990

Irradiation of malignant eyelid melanoma with iodine 125 plaque.

We used contact irradiation with iodine 125 seeds to treat a large, exulcerative, nodular, amelanotic malignant eyelid melanoma with metastasis to the regional lymph nodes in an 80-year-old man. The procedure was similar to iodine 125 plaque irradiation of malignant choroidal melanoma; special equipment, however, was needed to protect the eye from radiation exposure. The response of the malignant eyelid melanoma to iodine 125 plaque irradiation was similar to that of malignant melanomas of the choroid. No complications were observed in a follow-up period of 15 months.

Aged↗
PubMed1990

Relation of intraperitoneal and intravascular coagulation and fibrinolysis related antigens in peritoneal dialysis.

Patients received 2,000 ml of dialysate intraperitoneally with five exchanges per day during continuous peritoneal dialysis (CAPD) for the treatment of terminal renal insufficiency. During a dwell time of 4 h the dialysate reached a total protein concentration up to 100 mg/dl by mass transfer of intravascular proteins. The composition is dependent on the molecular weight of the proteins. This results in an intraperitoneal hemostatic system of low concentration and different composition. We found an intraperitoneal fibrinogen cleavage and thrombin-antithrombin III-complex formation leading to increased levels of fibrinopeptide A (FPA: 33.3 +/- 7.0 ng/ml) and thrombin-antithrombin III-complex (TAT: 4.7 +/- 0.4 ng/ml) in plasma by mass transfer from dialysate to plasma. t-PA (tissue plasminogen activator) and PAI-1 (plasminogen activator inhibitor type 1) concentrations in plasma were within the normal range. The dialysate concentrations indicated a low local secretion. The fibrinolytic fibrin fragment D-dimer and the fibrinogen degradation product concentrations in plasma were greater than in dialysate. But the relations of the proteins between plasma and dialysate refer to a local intraperitoneal production as well. The results show that intraperitoneal coagulation predominates over fibrinolysis which is accompanied by an intravascular fibrinolysis in patients undergoing CAPD. Neoantigens produced in dialysate and diffused to plasma are comparable to changes seen in disseminated intravascular coagulation.

Ascitic Fluid↗
PubMed1990

[Interstitial radiotherapy with 125I seeds in non-operable and non-radioiodine retaining local recurrences of differentiated and undifferentiated thyroid cancers].

The use of interstitial radiation therapy in the treatment of local recurrence of anaplastic and other carcinomas of the thyroid is discussed on the basis of four cases. 125I seeds were used except in 1 case. All tumours showed no uptake of radioiodine and could not be completely removed by surgery. In three patients local control of the tumour was achieved (longest follow-up 41 months); one patient died 2 months after therapy due to local recurrence.

Aged↗
PubMed1990

Temperature dependence of [3H]Ro 15-1788 binding to benzodiazepine receptors in human postmortem brain homogenates.

The temperature dependence of in vitro binding of [3H]Ro 15-1788 to benzodiazepine receptors in human postmortem neocortex and neocerebellum homogenates was studied. An increase of the equilibrium dissociation constants (KD) from 1.40 nmol/L and 1.04 nmol/L at 4 degrees C to 6.10 nmol/L and 8.91 nmol/L at 37 degrees C was found for neocortex and neocerebellum, respectively. In contrast, maximal binding (Bmax) remained in the range of 30-35 fmol/mg for neocortex and 24-27 fmol/mg of tissue (wet weight) for neocerebellum at all the temperatures. The KD of 6.10 nmol/L for neocortex at 37 degrees C in vitro is of the same order as the KD of 10 nmol/L obtained by positron emission tomography for [11C]Ro 15-1788 binding to benzodiazepine receptors in the human neocortex in vivo. The differences in KD between in vitro and in vivo benzodiazepine receptor binding to human neocortex and cerebellum seem to be due at least partially to temperature differences of in vitro and in vivo studies.

Brain↗
PubMed1990

Comparison of the in vitro receptor binding properties of N-[3H]methylspiperone and [3H]raclopride to rat and human brain membranes.

The aim of the present investigation was to study and compare the in vitro binding properties of the two radioligands N-[3H]methylspiperone ([3H]NMSP) and [3H]raclopride. These compounds, labeled with 11C, have been extensively used in positron emission tomography studies on central dopamine D2 receptors in schizophrenic patients, although with diverging results. One study (using [11C]NMSP) showed an increased dopamine receptor density in drug-naive schizophrenic patients, whereas in another study (using [11C]raclopride) the density in schizophrenic patients was no different from that in healthy controls. In the present study, using in vitro binding techniques, the density of the binding sites was found to be similar irrespective of which of the two radioligands was used (20 fmol/mg wet weight in rat striatum and 10 fmol/mg in human putamen; the 5-hydroxytryptamine 2 receptors were blocked with 40 nM ketanserin). [3H]NMSP had a 10-fold higher affinity (KD, 0.3 nM in rat striatum and 0.2 nM in human putamen) than [3H]raclopride (KD, 2.1 nM in rat striatum and 3.9 nM in human putamen), which was consistent with the longer dissociation half-life of [3H]NMSP compared with [3H]raclopride (14.8 and 1.19 min, respectively). There was an approximate overall similarity between the inhibition constants for five dopamine antagonists, chlorpromazine, haloperidol, raclopride, remoxipride, and NMSP, when using either radioligand. The Ki values were, however, two- to four-fold higher when using [3H]NMSP as the radioligand, irrespective of inhibiting compound, except for chlorpromazine (and haloperidol in human putamen). NMSP was found to inhibit the binding of [3H]raclopride competitively, whereas raclopride inhibited the binding of [3H]NMSP both competitively and noncompetitively. This difference suggests that part of the binding site is exclusively used by NMSP and can only be allosterically interfered with by raclopride. It is proposed that [3H]NMSP binds to an additional set of accessory binding sites, presumably located more distantly from the agonist binding active site than the sites to which [3H]raclopride binds.

Animals↗
PubMed1990

Identification of an immunodominant region on the isolated bovine leukaemia virus (BLV) major envelope protein gp51 by monoclonal antibodies presumably not exposed during natural BLV infection.

A panel of newly isolated monoclonal antibodies (MoAbs) is described which are specific for bovine leukaemia virus (BLV) envelope protein gp51. Epitope mapping using competition antibody binding assays and binding studies with gp51-related fusion proteins and synthetic peptides show that they are directed against seven independent antigenic determinants. Four of them are unrelated to the epitopes described earlier (Bruck et al., 1982a). We define three binding regions for the MoAbs on the gp51 molecule. The region between amino acids 170 and 217 is highly immunogenic when the isolated protein is used for immunization, and seems to be inaccessible for immune recognition when gp51 is associated with the virus envelope as it occurs during natural BLV infection.

Animals↗
PubMed1989

Regional distribution of neuropeptide Y mRNA in postmortem human brain.

The distribution of messenger RNA encoding neuropeptide Y (NPY) was studied in 11 different postmortem human brain regions using in situ hybridization histochemistry, and RNA blot analysis. In situ hybridization data revealed that the highest numerical density of labeled cells corresponded to neurons in accumbens area, caudate nucleus, putamen, and substantia innominata. Significantly fewer NPY mRNA-containing neurons were found in frontal and parietal cortex, amygdaloid body and dentate gyrus. No NPY mRNA-containing cells were found in substantia nigra. NPY mRNA-positive neurons from all regions studied showed relatively similar labeling, as revealed by computerized image analysis. Blot analysis showed an approximately 0.8 kb NPY mRNA in all brain regions studied, except in substantia nigra and cerebellum. Densitometric scanning of the autoradiograms revealed levels of NPY mRNA in the following order: putamen greater than caudate nucleus greater than frontal cortex (Brodmann areas 4 and 6) greater than temporal cortex (Brodmann area 38) greater than parietal cortex (Brodmann areas 5 and 7) greater than frontal cortex (Brodmann area 11). Hence, although NPY mRNA is widely distributed in neurons of the human brain large regional variation exists, with the highest expression in accumbens area and parts of the basal ganglia.

Aged↗
PubMed1989

Effect of collagen crosslinking on collagen-water interactions (a DSC investigation).

The effect of collagen cross-linking state on the collagen-water interaction was studied, using Differential Scanning Calorimetry (DSC) which allows the determination of unfreezable water, the variation of enthalpy (delta H) and temperatures of denaturation of collagen to gelatin transition. DSC was performed on intramuscular connective tissue purified with trypsin (control C), depolymerized with penicillamin (P), and reduced with borohydride (B); samples were adjusted with different water contents. For the three tissues, unfreezable water (Wu) and denaturation enthalpy change (delta H) increased with increasing moisture level (Wt); whereas, maximum denaturation temperature (phi M) decreased. The ability of this calorimetric method of investigation to characterize the collagen crosslink state is discussed: maximum limit values of delta H and of Wu decreased significantly with increasing collagen cross-linking degree. Minimum Wt necessary to reach the maximum delta H decreased with crosslinking degree. Likewise significantly different limit values of unfreezable water Wu were reached for smaller Wt the greater the crosslinking of collagen. These results show that the less connective tissues were cross-linked, the more they could bind water. They also demonstrated that the water of collagen hydration can be classified into four states, whose limits vary according to the degree of crosslinking.

Animals↗
PubMed1989

Dipeptidyl peptidase IV in human T lymphocytes. Impaired induction of interleukin 2 and gamma interferon due to specific inhibition of dipeptidyl peptidase IV.

Specific inhibitors of the membrane-bound dipeptidyl peptidase IV (DP IV) and polyclonal antibodies against this enzyme were used to investigate the relationships between DP IV activity and the production and action of T cell-derived lymphokines. Production of interleukin 2 (IL-2) and gamma interferon by mitogen plus phorbol ester-stimulated mononuclear cells from human blood was found to be reduced in the presence of N-Ala-Pro-O-(nitrobenzoyl-)-hydroxylamine, epsilon-(4'-nitro) benzoxycarbonyl-Lys-Pro, and anti-(DP IV) immunoglobulin in a dose-dependent manner. Moreover, the proliferative response of mitogen-stimulated mononuclear cells to IL-2 is impaired in the presence of DP IV inhibitors. Therefore it is suggested that the membrane peptidase DP IV is involved in the induction and activation of cytokines controlling lymphocyte proliferation.

Cells, Cultured↗