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Biomedical subjects

G Adam

Publications and source records attributed to G Adam.

At least 235 records · Page 13Linked to original sources
PubMed1994

3,4-Dihydro-3-amino-2H-1-benzopyran derivatives as 5-HT1A receptor ligands and potential anxiolytic agents. 1. Synthesis and structure--activity relationship studies.

A series of 3,4-dihydro-3-amino-2H-1-benzopyran derivatives were prepared in order to determine the necessary structural requirements for good affinity for 5-HT1A receptors and high selectivity versus other receptors. Modifications of the extracyclic amino substituents, the length of the alkyl side chains, and their substituents were explored. The best compounds (9g, 9k, 15b, 15d) possess imido or sulfonamido functional groups with a preferential length of four methylenes for the side chain. After resolution, the dextrorotatory enantiomers showed better affinity and selectivity for 5-HT1A receptors. These compounds have been proven to be full agonists. 9g and its enantiomers showed anxiolytic activity in vivo in various comportemental models. The compound (+)-9g is currently under clinical investigation.

Animals↗
PubMed1994

Dynamic contrast-enhanced MR imaging of the upper abdomen: enhancement properties of gadobutrol, gadolinium-DTPA-polylysine, and gadolinium-DTPA-cascade-polymer.

The enhancement properties of gadobutrol (40 and 80 mumol/kg body weight, 550 daltons), gadolinium-DTPA-polylysine (20 mumol/kg body weight, 53,000 daltons) and gadolinium-DTPA-cascade-polymer (20 mumol/kg body weight, < 30,000 Daltons) were investigated in abdominal MR imaging using a pig model (n = 24). Signal intensities before and after contrast media application were assessed using a fast single slice FLASH sequence. Measurements were made every 4 s within the first 116 s, every minute between 4 and 10 min and after 15, 20, 30, 40, 50, 60, 90, and 120 min after contrast media injection. Injection of gadobutrol resulted in typical signal intensity curves characterizing it as an extracellular agent similar to gadopentetate dimeglumine. Significant enhancement was found in all tissues except the trunk muscles when the lower dose was administered. Gadolinium-DTPA-polylysine injection resulted also in significant enhancement of the liver, the pancreas, and the renal cortex, but not of the trunk muscle, reflecting its blood pool properties known also from other macromolecular contrast agents. The signal intensity curves obtained after gadolinium-DTPA-cascade-polymer injection were similar to those obtained after polylysine injection, stressing the blood pool character of this new type of blood pool agent.

Abdomen↗
PubMed1994

[MRI of the hyaline knee joint cartilages. Animal and clinical studies].

The value of MR imaging for the detection of hyaline cartilage lesions using 2-D spin-echo and 3-D gradient-echo imaging was evaluated in an animal experiment in 10 dogs and in a clinical study in 30 patients. MR imaging findings were compared with histopathological and arthroscopy findings, respectively. Using MRI neither grade I nor grade II hyaline cartilage lesions were detectable. In the animal experiments 77% of grade III lesions and all the grade IV lesions were seen. However, in the clinical study only about the half of grade III and IV lesions were detected. 3-D gradient-echo MR imaging was superior to 2-D spin-echo imaging (p < 0.001), while 3-D FLASH and 3-D FISP did not differ significantly in the detection rate (p < 0.34). 3-D gradient-echo MR imaging seems to be the best method for the delineation of high grade cartilage lesions. However, early stages of cartilage degeneration are invisible even with this imaging modality.

Adult↗
PubMed1994

[The magnetic resonance tomography of osteochondrosis dissecans of the knee joint after intravenous gadolinium-DTPA administration].

20 patients with osteochondritis dissecans were studied by MRI over a period of 3-34 months in order to observe healing and determine the viability of the loose fragment. After intravenous contrast, there was increased signal intensity at the junction between the fragment and the epiphyseal bed on T2-weighted sequences; this was interpreted as fibrous granulation tissue surrounding the fragment. The fragments themselves also showed increased signal intensity after gadolinium-DTPA. Intravenous gadolinium allows accurate evaluation of the junctional zone between the fragment and the epiphyseal bed by demonstrating fibrous, vascularised granulation tissue. This can be distinguished from synovial fluid, and it also demonstrates viability of the fragment.

Adolescent↗
PubMed1994

Studies on the interaction of roxindole with brain monoamine oxidases and dopaminergic neurones in vitro and in vivo.

Roxindole, a structurally novel psychotropic indolylbutyl-4-phenyltetrahydropyridine, was studied with respect to the formation of potentially neurotoxic pyridinium metabolites in comparison to MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine). In contrast to MPTP, roxindole failed to serve as a substrate for monoamine oxidases (MAO) from mouse, monkey and human brain in vitro. Accordingly, neither the putative MAO-oxidation product of roxindole (ROX+) nor MPP+ (1-methyl-4-phenylpyridinium ion) was detected in mouse striatum after high subcutaneous doses of roxindole in spite of the presence of approximately 6 micrograms of roxindole per g of striatum in these animals. After multiple subcutaneous treatments with 95.2 mg/kg roxindole, no long-term striatal dopamine depletions were observed in contrast to MPTP. Furthermore, unlike MPP+, ROX+ did not induce release of previously accumulated 3H-dopamine in mouse striatal slices indicating that ROX+ cannot utilize the dopamine uptake carrier to enter neurones. ROX+ at doses up to 100 mg/kg subcutaneously failed to alter striatal biogenic amine levels and gross behaviour of mice. Thus, no MPTP-like neurotoxic metabolites are formed from roxindole in vivo and neurotoxic effects of ROX+, even if formed in minute amounts by some MAO-independent pathway, are highly unlikely.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1994

Proliferative and metabolic capacity of rat embryo fibroblasts immortalized by c-myc depends on cellular age at oncogenic transfection.

It is well known that secondary rat embryo fibroblasts are immortalized and transformed with respect to requirements of growth factors by transfection with an overexpressed c-myc protooncogene. On the other hand, c-myc expression of nontransformed cells was shown to be independent of cellular age in vitro. In order to elucidate further the role of the c-myc protooncogene in the process of aging of rat embryo fibroblasts, we have transfected these cells at low (< or = 2) and at high (> or = 16) cumulative population doublings with SV40-promoter/enhancer-driven murine c-myc. These cells transformed young or aged, as well as their nontransformed, young and aged controls, were characterized with respect to their expression of c-myc at the mRNA and the protein level. Furthermore, we have investigated in detail their cell density-dependent growth, dependence of cell proliferation on stimulation by combinations of growth factors, and dependence of entry into cell cycle on cell size. In addition, we have measured rates of synthesis and degradation of cellular RNA and protein. The main result was that cells transformed at old age cannot be distinguished from nontransformed old cells by any of the characteristics investigated except by their immortalization. Thus, the cell lines overexpressing c-myc are immortalized and fixed in the proliferative/metabolic state achieved at the time of transfection. It is concluded that the intracellular effects of c-myc depend on the epigenetic status of the cells.

Animals↗
PubMed1994

[Fine needle punch biopsy of the lung. Results and complications].

The diagnostic accuracy and complication rate of computer tomography (CT)-guided small-caliber cutting needle biopsy were assessed in 103 biopsies in 101 consecutive patients. There were 67 true-positive, 30 true-negative, 3 false-negative and no false positive results. Two specimens were unclassifiable and one was insufficient. Diagnostic accuracy was 94.1%, sensitivity 95.7%, and specificity 100%. In 34% of cases pneumothorax occurred, requiring therapy in 24% of cases. The longer the intrapulmonary biopsy route was, the greater the risk of pneumothorax. Except for transient hemoptysis in two patients, there were no further complications. CT-guided small-caliber cutting needle biopsy of the lung is an effective and safe procedure, comparing well with fine needle aspiration biopsy (FNAB). If exact histologic diagnosis is required it should be preferred to FNAB.

Adult↗
PubMed1993

A Saccharomyces cerevisiae UAS element controlled by protein kinase A activates transcription in response to a variety of stress conditions.

Transcription of the Saccharomyces cerevisiae CTT1 gene encoding the cytosolic catalase T is activated by a variety of stress conditions: it is derepressed by nitrogen starvation and induced by heat shock. Furthermore, it is activated by osmotic and oxidative stress. This study shows that a CTT1 upstream region previously found to be involved in nitrogen, cAMP and heat control (base pairs -382 to -325) contains a UAS element (STRE, -368 to -356), which is sufficient for the activation of a reporter gene by all types of stress acting on CTT1. Gel retardation experiments demonstrated the existence of a factor specifically binding to STRE, but to a lesser extent to mutated elements having partly or entirely lost the ability to mediate stress control. Heat activation of STRE, but not of a canonical heat shock element, is enhanced by a ras2 defect mutation, which enhances thermotolerance, and is dramatically reduced by a bcy1 disruption mutation, which decreases thermotolerance. It can be hypothesized, therefore, that the novel stress control element is important for the establishment of induced stress tolerance.

Base Sequence↗
PubMed1993

Serological comparison of tospovirus isolates from Taiwan and India with impatiens necrotic spot virus and different tomato spotted wilt virus isolates.

Tospovirus isolates from tomato and watermelon in Taiwan and from peanut in India reacted neither with antibodies to tomato spotted wilt virus (TSWV), nor with antibodies to impatiens necrotic spot virus (INSV), in ELISA and in electroblot immunoassays. Additionally, all three tospovirus isolates had an N protein with a molecular weight of 32 kDa as compared to 29 kDa for the N protein to TSWV and INSV. The observed physicochemical and serological differences suggest the generation of a new, third species in the genus tospovirus for which we propose the name groundnut bud necrosis virus.

Antigens, Viral↗
PubMed1993

Hydroxylation of the native brassinosteroids 24-epicastasterone and 24-epibrassinolide by the fungus Cunninghamella echinulata.

24-Epicastasterone and 24-epibrassinolide, two naturally occurring phytohormones of the brassinosteroid type, were transformed by the fungus Cunninghamella echinulata to give the corresponding 12 beta-hydroxylated compounds. The structures of these compounds were determined by spectroscopic methods, especially heterocorrelated two-dimensional nuclear magnetic resonance investigations. In the rice lamina inclination test the 12 beta-hydroxylation lowered the bioactivity at 0.1 ppm to 10% in comparison with that of the corresponding parent hormones. The described hydroxylations represent the first biotransformations of native brassinosteroids.

Brassinosteroids↗
PubMed1993

Influence of (22S,23S)-homobrassinolide on rooting capacity and survival of adult Norway spruce cuttings.

To determine whether brassinosteroids promote clonal propagation of mature coniferous trees, cuttings of adult Norway spruce (Picea abies (L.) Karst.) trees were harvested in late March, treated with (22S,23S)-28-homobrassinolide (SSHB), and stored at 2 degrees C in darkness until they were planted in May. Treatment of the cuttings with SSHB significantly enhanced the formation of adventitious roots by increasing percent rooting from 50% in the control cuttings to 92% in the 60 ppm SSHB treatment. N(6)-Benzyladenine (BA) stimulated rooting slightly although not significantly, but it counteracted the stimulative effect of SSHB when cuttings were treated with both compounds together. In a second study, the above-ground parts of medium-sized mature clonal Norway spruce trees were pretreated from the end of June till August with SSHB or BA or both. Needle retention of cuttings taken from the pretreated trees the following spring was prolonged until September and the cuttings flushed, but did not root, whereas cuttings from untreated stock plants died before September. No interaction between BA and SSHB was observed. When these pretreatments were repeated the following year on the same mature clonal trees rooting of cuttings was significantly improved in the 5 ppm SSHB treatment.

Journal Article↗
PubMed1993

[Osteomyelitis today--diagnostic imaging and therapy].

Plain radiography, bone scan and especially in infants sonography belong to the primary imaging methods for posttraumatic osteomyelitis. For further diagnostic check up of osteomyelitis CT, MRI and leukocyte scintigraphy are excellent methods. Treatment of posttraumatic osteomyelitis is today a combination of operation, local and systemic antibiotic therapy.

Adolescent↗
PubMed1992

Type 1 ribosome-inactivating proteins depurinate plant 25S rRNA without species specificity.

Four different type 1 ribosome-inactivating proteins (RIPs) with RNA N-glycosidase activity were tested for their ability to attack the large rRNA of plant ribosomes derived from tobacco plants, as well as from the plant species from which the particular RIP had been isolated. Incubation of tobacco ribosomes with RIPs isolated from either Phytolacca americana L. (pokeweed), Dianthus barbatus L. (carnation), Spinacia oleracea L. (spinach) or Chenopodium amaranthicolor Coste and Reyn. (chenopodium) rendered the 25S rRNA sensitive to aniline-catalyzed hydrolysis, generating a single rRNA-fragment of about 350 nucleotides. The same fragment was generated when rRNAs from pokeweed, carnation, spinach or chenopodium ribosomes were aniline-treated without any deliberate treatment of the ribosomes with the respective RIP. This indicated that ribosomes from all RIP-producing plants were already inactivated by their own RIPs during preparation. These results demonstrate that plant ribosomes are generally susceptible to RIP attack, including modification by their own RIPs. Direct sequencing of the newly generated fragments revealed that a single N-glycosidic bond at an adenosine residue within the highly conserved sequence 5'-AGUACGAGAGGA-3' was cleaved by all of the RIPs investigated, a situation also found in animal, yeast and Escherichia coli ribosomes.

Base Sequence↗
PubMed1992

Control of peroxisome proliferation in Saccharomyces cerevisiae by ADR1, SNF1 (CAT1, CCR1) and SNF4 (CAT3).

The Saccharomyces cerevisiae ADR1 gene has recently been demonstrated to control transcription of several genes encoding peroxisomal proteins or proteins necessary for peroxisome formation. Therefore, the effect of two other genes (SNF1 (CAT1, CCR1) and SNF4 (CAT3)) known to control derepression of glucose-repressible genes was studied. Levels of transcripts of genes encoding catalase A, fatty acid beta-oxidation enzymes and of the PAS1 gene are reduced in snf1 and snf4 mutants on ethanol as well as on oleic acid medium. By immunogold labelling with an antibody directed against peroxisomal thiolase, clusters of peroxisomes were detected in wild-type cells, whereas smaller single peroxisomes were observed in adr1 mutant cells. Results of immunofluorescence experiments are consistent with these observations. No peroxisomes were detected in snf1 and snf4 mutants by immunogold labelling as well as by immunofluorescence.

Acetyl-CoA C-Acetyltransferase↗