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J Maier

Publications and source records attributed to J Maier.

At least 37 records · Page 2Linked to original sources
PubMed1997

Neurochemical compartments in the human forebrain: evidence for a high density of secretoneurin-like immunoreactivity in the extended amygdala.

Secretoneurin is a 33-amino acid neuropeptide produced by endoproteolytic processing from secretogranin II, which is a member of the chromogranin/ secretogranin family. In this immunocytochemical study we investigated the localization of secretoneurin-like immunoreactivity in the human substantia innominata in relation to the ventral striatopallidal system, the bed nucleus-amygdala complex and the basal nucleus of Meynert. A high density of secretoneurin immunostaining was found in the medial part of the nucleus accumbens. All subdivisions of the bed nucleus of the stria terminalis displayed a very prominent immunostaining for secretoneurin, whereas substance P and enkephalin showed a more restricted distribution. A high concentration of secretoneurin immunoreactivity was also observed in the central and medial amygdaloid nuclei. In the lateral bed nucleus of the stria terminalis and the sublenticular substantia innominata, the appearance of secretoneurin immunoreactivity was very similar to that of enkephalin-like immunoreactivity, exhibiting mostly peridendritic and perisomatic staining. The ventral pallidum and the inner pallidal segment displayed strong secretoneurin immunostaining. Secretoneurin did not label cholinergic neurons in the basal forebrain. This study demonstrates that secretoneurin-like immunoreactivity is prominent in the bed nucleus-amygdala complex, referred to as extended amygdala. The distribution of secretoneurin-like immunoreactivity in comparison with that of other neuroanatomical markers suggests that this forebrain system is a discret compartment in the human forebrain.

Adult↗
PubMed1997

Uptake and cellular localization of exogenous lipids by Giardia lamblia, a primitive eukaryote.

Giardia lamblia trophozoites are unable to carry out de novo lipid synthesis. It is therefore likely that lipids are acquired from the small intestine of the host, in which the trophozoites are exposed to free and conjugated fatty acids, various sterols, phospholipids, bile acids, and bile-lipid mixed micelles. Here we show that G. lamblia is capable of taking up exogenous phosphatidylcholine (PC), phosphatidylinositol (PI), sphingomyelin (SM), cholesterol, ceramide (Cer), and fatty acids. Results from epifluorescence and high-resolution confocal microscopy suggest that fluorescent analogs of SM and PC were accumulated in the plasma membranes, whereas palmitic acid and Cer were localized intracellularly. Interestingly, many of these analogs were also concentrated in perinuclear regions. Similar labeling patterns were observed when the fluorescent analogs were delivered to the parasite via liposomes. To test whether G. lamblia was capable of esterifying exogenous fatty acids into membrane or cellular phospholipids, trophozoites were pulse-labeled with 3H-labeled palmitic or myristic acids and the phospholipids analyzed by thin-layer chromatography. Results document that G. lamblia was able to incorporate exogenous fatty acids into various phospholipids, i.e., PI, PC, PE, and PG. Interestingly, a major portion of radiolabeled fatty acids was incorporated into PG, a phospholipid characteristic of prokaryotic membranes.

Animals↗
PubMed1997

Inhibition of pteridine biosynthesis eliminates blue-light dependent stimulation of red-light saturated photosynthesis in Laminaria saccharina (L.) Lamouroux.

Blue-light stimulation of red light-saturated photosynthetic oxygen evolution in Laminaria saccharina (L.) Lamouroux could be abolished within 5 days by incubation in a solution of 2,4-diamino-6-hydroxypyrimidine (DAHP), an inhibitor of GTP-cyclohydrolase I (E.C.3.5.4.16) activity. Photosynthesis in red light was not detectably affected. GTP-cyclohydrolase I, which catalyses the first step in the biosynthetic pathway of pteridines, was shown to be active in Laminaria. Under conditions that lead to complete inhibition of the photosynthetic stimulation, DAHP reduced the content of the pteridines in the tissue considerably. The amount of pterin was about 14%, that of biopterin was about 45% and that of an unidentified pteridine was about 27% of those of the controls. By contrast, the total concentration of flavins (FAD + FMN - riboflavin) was not significantly affected. The results suggest that pterins may be involved in the response of photosynthesis to blue light, possibly participating in photoreception.

Chromatography, High Pressure Liquid↗
PubMed1996

Interleukin 1 induces an autocrine loop hepatocyte growth factor/c-Met in murine Kaposi-like spindle cells.

Several cytokines, growth factors and the HIV transactivator Tat were shown to be involved in the pathogenesis of Kaposi's sarcoma. BKV/tat transgenic mice develop Kaposi's sarcoma-like lesions, and spindle-shaped cells (TTB) have been derived from these lesions. Here we show that TTB cells co-express hepatocyte growth factor (HGF) and its receptor, the product of the oncogene c-Met. An autocrine loop HGF/Met sustains spindle cell proliferation in vitro; indeed, an antisense oligomer targeted against HGF markedly inhibited cell growth. Moreover, HGF and Met are overexpressed after exposing TTB cells to the proinflammatory cytokine interleukin 1 (IL-1). We argue that upon exposure to IL-1, an HGF/Met autocrine loop is induced which could explain the appearance of multiple foci of uncontrolled growth. In addition, due to its angiogenic activity, HGF may also sustain the neovascularization typical of Kaposi's sarcoma lesions.

Animals↗
PubMed1996

Cardiac troponin I in the diagnosis of myocardial injury and infarction.

We used a cardiospecific enzymoimmunometric assay to measure cardiac troponin I (cTnI) in samples serially drawn from 78 patients with acute myocardial infarction (AMI), 7 patients with unstable angina (Braunwald class III), 22 multi-traumatized patients, and in 30 athletes after eccentric exercise, as well as in 101 non-traumatic chest pain patients on admission to the emergency department. cTnI assay crossreactivity with crude human skeletal muscle homogenates was < 0.1%. cTnI could not be detected in athletes or multi-traumatized patients except for 2 trauma patients with myocardial damage. Increased cTnI concentrations were found in 6 of 7 patients with unstable angina at rest and in all AMI patients. After AMI, cTnI increased about 3.5 h (median) after the onset of chest pain, reached peak values parallel to CKMB, and stayed increased for at least 4 days. Cardiac troponin T (cTnT) increased and mostly peaked parallel to cTnI. cTnT sensitivity on the 7th day after AMI was significantly higher than that of cTnI. In contrast to cTnI, cTnT mostly showed a second, usually smaller, peak about day 4 after AMI. During the first 4 h after the onset of chest pain and before thrombolytic therapy the sensitivities of myoglobin (0.43) and CKMB mass (0.56) were significantly higher than those of both troponins (cTnI, 0.29; cTnT, 0.25). Areas under receiver operator characteristic curves indicated only moderate diagnostic accuracies of bio-chemical markers for early AMI diagnosis in non-traumatic chest pain patients that cTnI is a highly sensitive and specific marker for myocardial damage which is suitable for early and late diagnosis.

Adult↗
PubMed1996

Progress in the prostaglandin E1-therapy of the intermittent claudication by means of bolus injections of LIPO-prostaglandin E1 (LIPO-PGE1).

OBJECTIVE: We compared the efficacy of a bolus injection (5 min) of LIPO-PGE1 (Prostaglandin E1 in lipid emulsion) with conventional PGE1-cyclodextrin (PGE1-cyclodextrin) infusions (2 h) in patients with intermittent claudication. The quantitative blood-flow in the common femoral artery was measured using a computerized ultrasound Doppler system (MAVIS). We also monitored the transcutaneous oxygen pressure, the skin temperature on the foot, and the reactive change in blood pressure and pulse as well as side effects. RESULTS: Dose finding of LIPO-PGE1: After bolus injection of 30, 50, and 80 micrograms LIPO-PGE1 a significant dose-dependent increase of the blood flow in the leg (+96.9%, 80 micrograms) with a peak 3 h after injection was seen. After LIPO-PGE1 we observed an enhanced microcirculation (significant rise in the transcutaneous oxygen pressure and the skin temperature on the foot). We noted longer lasting pharmacodynamic properties with LIPO-PGE1 (50 micrograms) compared to PGE1-cyclodextrin (60 micrograms). Comparison to PGE1-cyclodextrin: In a cross-over, placebo-controlled study, 20 patients with intermittent claudication received 4 weeks therapy with a bolus of 50 micrograms LIPO-PGE1 or a 2 h infusion of 60 micrograms PGE1-cyclodextrin per day. A significant increase in the blood flow was measured at the end of 4 weeks therapy compared to the initial values before treatment. This rise correlates significantly with the increase in the patient's maximal walking distance (+112%, LIPO-PGE1). Compared to conventional PGE1-cyclodextrin infusions given over 2 h, a clearly prolonged increase in perfusion of the affected limb after LIPO-PGE1 was demonstrated. No serious adverse effects were observed.

Aged↗
PubMed1996

Indications for the occurrence of nitric oxide synthases in fungi and plants and the involvement in photoconidiation of Neurospora crassa.

Indications for the occurrence of nitric oxide synthases in Dictyostelium, Neurospora, Phycomyces and the leguminous plant Mucuna hassjoo as well as a physiological role of nitric oxide in Neurospora crassa are demonstrated. An exogenous nitic oxide donor, sodium nitroprusside, inhibited light-stimulated conidiation in N. crassa. Specific inhibitors of nitric oxide synthase, like the arginine derivatives NG -nitro-L-arginine (L-NA) and NG-nitro-L-arginine-methyl ester (L-NAME), enhanced conidiation in darkness nad in the light, whereas the stereoisomer D-NAME was inactive. This communication reports to our knowledge the first time the presence of enzymatic activity of nitric oxide synthase in fungi and a higher plant and an effect of nitric oxide in fungal photo-physiology.

Darkness↗
PubMed1995

Homology cloning of GTP-cyclohydrolase I from various unrelated eukaryotes by reverse-transcription polymerase chain reaction using a general set of degenerate primers.

GTP-cyclohydrolase I is the primary enzyme of tetrahydrobiopterin and folic acid biosynthesis. cDNA fragments of GTP-cyclohydrolase I were obtained from rainbow trout, chicken, the fungi Neurospora crassa, Phycomyces blakesleeanus and Saccharomyces cerevisiae, the cellular slime mold Dictyostelium discoideum, the phytoflagellate Euglena gracilis and the higher plant Mucuna hassjo using primers specific for conserved regions of the open reading frame and the reverse transcription polymerase chain reaction (RT-PCR) technique. A number of regions were found to be strictly conserved between unrelated eukaryotes. These regions may be essential for the function of GTP-cyclohydrolase I and are discussed with respect to the recently resolved crystal structure of the Escherichia coli enzyme.

Amino Acid Sequence↗
PubMed1995

Biosynthesis of pteridines in Neurospora crassa, Phycomyces blakesleeanus and Euglena gracilis: detection and characterization of biosynthetic enzymes.

Occurrence, biosynthesis and some functions of tetrahydrobiopterin (H4biopterin) in animals are well known. The biochemistry of H4biopterin in other organisms than animals was hitherto not widely investigated. Recently H4biopterin was found in the phytoflagellate Euglena gracilis, in the zygomycete Phycomyces blakesleeanus and in the ascomycete Neurospora crassa. In Euglena, Neurospora and Phycomyces the enzymatic activities of GTP cyclohydrolase I, 6-pyruvoyl tetrahydropterin synthase and sepiapterin reductase are detectable and the biosynthesis follows the same steps as were shown for animals. The biosynthetic enzymes, however, show a much lower sensitivity to those inhibitors that act on vertebrate enzymes. 2,4-Diamino-6-hydroxypyrimidine as inhibitor of GTP cyclohydrolase I and N-acetylserotonin or N-methoxyacetylserotonin as inhibitors of sepiapterin reductase can decrease pteridine biosynthesis significantly, in vitro and in vivo. The apparent Km values are in general higher when compared with the respective animal enzymes. In Neurospora, the conversion of GTP to dihydroneopterin triphosphate was closely associated with subsequent production of 6-hydroxymethyl-7,8-dihydropterin due to the high activity of dihydroneopterin aldolase, different from all other tested organisms. Investigations involving inhibition of pteridine synthesis might be a useful tool for evaluating the hypothesis that pteridines in fungi and plants are co-chromophores of various blue light-dependent, flavin-containing photoreceptors.

Alcohol Oxidoreductases↗
PubMed1993

Detection of a novel sepiapterin reductase mRNA: assay of mRNA in various cells and tissues of various species.

Fragments of cDNA coding for rat, murine, and human sepiapterin reductase (SR) were amplified by PCR via primer positioning close to the reported 3'-end of the coding region in the rat enzyme. They were sequenced and used as probes for mRNA detection. Northern blot analysis detected two mRNA species for SR. Their sizes were 1.3 and 2.1 kb for rat, 1.3 and 2.3 kb for mouse, and 1.6 and 2.1 kb for human cell lines. Comparison of rat cell lines and rat tissues indicated that in tissues only the 1.3-kb species is present. Washing of the Northern blots under different stringency conditions indicated a more stable interaction of the 1.3-kb mRNA species with the cDNA probe as compared to the 2.3-kb species. The 1.3-kb species corresponds to the reported 28.2-kDa molecular mass of rat SR monomer. SR mRNA expression is absent in the human NK-like cell line YT and in the murine erythroleukemia subclone B8/3, which both lack SR activity. Moreover, the relative mRNA expression correlates with the enzymatic activities of different cell lines within the same species. This indicates that SR activity is regulated by its steady state mRNA levels.

Alcohol Oxidoreductases↗
PubMed1993

Plasma immunoreactive endothelin in the acute and subacute phases of myocardial infarction in patients undergoing fibrinolysis.

Endothelin is a potent vasoconstrictor of coronary arteries. We measured plasma concentrations of immunoreactive endothelin (irET) in 46 patients with confirmed acute myocardial infarction (AMI). When compared with irET concentrations in healthy individuals who served as controls, irET concentrations in patients were already significantly elevated at the time of admission (P = 0.002) and remained significantly elevated for at least 2 days after AMI (P < 0.01). IrET concentrations peaked 1 h (mean) after admission (8.5 +/- 3.9 ng/L, P = 0.02 compared with values at time of admission). Reperfusion of the infarct-related artery markedly influenced irET release. Before the start of thrombolytic therapy, irET concentration in patients with early reperfusion did not differ significantly from that of those without early reperfusion. However, irET time courses were significantly (P = 0.03 by analysis of variance) different in patients who did and did not have early reperfusion. In the latter, peak irET concentrations correlated closely with the angiographic left ventricular ejection fraction (r = -0.71, P = 0.03), maximum creatine kinase MB mass concentrations (r = 0.69, P = 0.01), and creatine kinase activities (r = 0.59, P = 0.03). Reflow and reversion of myocardial ischemia are associated with a reduced irET release in patients with AMI.

Adult↗
PubMed1992

Endothelin-1 in patients with complicated and uncomplicated myocardial infarction.

Endothelin-1 concentrations were measured in peripheral venous blood samples from 42 patients with acute myocardial infarction. In patients with ischemic or hemodynamic complications (n = 11), endothelin-1 concentrations were significantly higher already on admission (P = 0.008) and remained significantly higher until day 6 after admission compared to patients with uncomplicated infarctions (n = 31; P = 0.035). There were no close correlations between peak concentrations of endothelin-1 and creatine kinase or creatine kinase isoenzyme MB mass in either group. Only in complicated patients did left ventricular ejection fraction correlate closely and inversely with peak endothelin-1 concentrations (r = -0.71; P = 0.03). Therefore, plasma endothelin-1 concentrations in patients with acute myocardial infarction patients may reflect states of markedly depressed cardiac performance and recurrent myocardial ischemia.

Adult↗