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Biomedical subjects

G Adam

Publications and source records attributed to G Adam.

At least 253 records · Page 14Linked to original sources
PubMed1992

Triterpenoids and their glycosides from the bark of Schefflera octophylla.

A new triterpene and its glycosides were isolated from the bark of Schefflera octophylla together with asiatic acid and asiaticoside. Based on spectroscopic data, especially 2DNMR, and chemical transformations the structures of the new compounds were determined as 3 alpha-hydroxy-urs-12-ene-23,28-dioic acid and 3 alpha-hydroxy-urs-12-ene-23,28-dioic acid 28-O-[alpha-L-rhamnopyranosyl (1----4)-O-beta-D-glucopyranosyl (1----6)]-beta-D-glucopyranoside. For the first time asiaticoside was isolated from a plant other than Centella asiatica.

Carbohydrate Sequence↗
PubMed1992

Withanolide glycosides from Dunalia australis.

Four new withanolide glycosides, (20R,22R)-O-(3)-[beta-D- xylopyranosyl(1----3), beta-D-xylopyranosyl(1----4)]-beta-D-glucopyranosyl-3 beta,20-dihydroxy-1 alpha-acetoxy-witha-5,24-dienolide, (20R,22R)-O-(3)-[beta-D-xylopyranosyl(1----3), beta-D-glucopyranosyl(1----4)]-beta-D-glucopyranosyl-3 beta,20-dihydroxy-1 alpha-acetoxy-witha-5,24-dienolide, (20R,22R)-O-(3)-[beta-D- glucopyranosyl(1----3), beta-D-glucopyranosyl(1----4)]-beta-D-glucopyranosyl- 3 beta,20-dihydroxy-1 alpha-acetoxy-witha-5,24-dienolide and (20R,22R)-O-(3)-[beta-D-glucopyranosyl(1----3), beta-D- glucopyranosyl(1----4)]-beta-D-glucopyranosyl-3 beta, 12 beta,20-trihydroxy- 1 alpha,acetoxy-witha-5,24-dienolide, named dunawithanines C, D, E and F, respectively, were isolated from Dunalia australis. Their structures were elucidated on the basis of spectral and chemical evidence, especially NMR data of the peracetates.

Carbohydrate Sequence↗
PubMed1992

Sesquiterpenoids from the roots of Homalomena aromatica.

From roots of Homalomena aromatica three new sesquiterpene alcohols, 1 beta, 4 beta, 7 alpha-trihydroxyeudesmane, homalomenol A, and homalomenol B were isolated together with oplopanone, oplodiol and bullatantriol. The structures of the new constituents were elucidated by spectroscopic investigations and chemical transformations.

Magnetic Resonance Spectroscopy↗
PubMed1992

An acetylated bidesmosidic saponin from Schefflera octophylla.

A new acetylated bidesmosidic triterpenoid saponin has been isolated from the leaves of Schefflera octophylla and structurally elucidated as 3-epi-betulinic acid 3-O-beta-D-6'-acetylglucopyranoside 28-[alpha-L-rhamnopyranosyl(1----4)-O-beta-D-glucopyranosyl(1----6)]-bet a-D-0-glucopyranoside [1].

Carbohydrate Sequence↗
PubMed1992

[Computed tomographic studies on density kinetics after the bolus injection and infusion of perfluorooctylbromide (PFOB). Animal experimental studies].

We investigated the enhancement of the liver, the spleen, and of induced abscesses and the abdominal vessels after administration of 3 g/kg bodyweight. Perfluorooctylbromide (PFOB) in an animal model. Twenty-one rabbits each received the contrast medium as bolus injection and as slow infusion over half an hour. CT was performed between 2 and 48 hours after contrast medium application. Peak enhancement of the liver, the spleen and the liver abscess membrane was found between 24 and 48 hours after PFOB administration, independently of the application mode. Peak enhancement of the abdominal aorta and the IVC was observed within two hours after bolus injection. In this rabbit model PFOB permits best delineation of the vessels after bolus injection within the first two hours, while CT imaging of the liver, the spleen and the liver abscess membrane is best between 24 and 48 hours after contrast medium application, independent of the injection velocity.

Animals↗
PubMed1992

Computed tomographic enhancement of the liver, liver abscesses, spleen, and major vessels with perfluorooctylbromide emulsion. Influence of dosage and injection velocity in an animal model.

RATIONALE AND OBJECTIVES: Computed tomographic (CT) enhancement of the liver, liver abscess, spleen, and major vessels was investigated between 2 and 48 hours after intravenous administration of perfluorooctylbromide (PFOB emulsion) in an animal model of 63 rabbits. METHODS: Twenty-one animals received 3 g/kg PFOB as a fast bolus injection. Using a slow infusion rate, the same number of animals received either the same dose (3 g/kg) or half the dose (1.5 g/kg). RESULTS: Vascular enhancement was best after bolus injection of 3 g/kg emulsion. The density peak occurred after 2 hours. A continuous enhancement of approximately 100 Hounsfield units (HU) was observed up to 24 hours in the animals receiving 3 g/kg, independent of the injection velocity. A density peak of 70 HU was found 2 hours after the infusion of 1.5 g/kg. The density peak of the liver, the spleen, and the abscess wall was observed 48 hours after emulsion administration in all groups receiving 3 g/kg. The peak was approximately 150 HU for the liver, 400 HU for the spleen, and 150 HU for the abscess wall. In animals receiving only 1.5 g/kg perflubron, the peak density of the abscess wall was 132 HU after 12 hours, approximately 80 HU for the liver between 2 and 48 hours, and approximately 280 HU after 48 hours for the spleen. CONCLUSIONS: PFOB emulsion produces the highest vascular enhancement within the first 2 hours after the bolus injection of 3 g/kg. For spleen and abscess wall imaging, even the relatively low dose of 1.5 g/kg produced a satisfactory enhancement level for a significant length of time, whereas liver enhancement was best after administration of the higher dose.

Animals↗
PubMed1992

The late presentation of postero-lateral congenital diaphragmatic hernias.

Four patients presenting after the neonatal period with a combination of respiratory and gastro-intestinal symptoms and signs which point to the diagnosis of congenital postero-lateral diaphragmatic hernias are discussed. Late presentation is more common than previously acknowledged. Early correct diagnosis and treatment are associated with an excellent clinical outcome.

Adult↗
PubMed1992

[Pseudotumoral thoracic actinomycosis with lung and brain metastases. Apropos of a case. Review of hundred thirty one cases in the literature].

One particular case of thoracic actinomycosis is reported. The patient presented with a neurological picture mimicking a metastasis, as chest radiogram and CT-Scan indicated a primary pulmonary tumor. Diagnosis of actinomycosis was overlooked and final diagnosis was based on direct microscopy of lung tumor, which required a thoracotomy, without any resection. Antibiotic treatment with penicillin was successful as the cerebral lesion was completely cured within 2 months and the thoracic lesion reduced 2/3rd volume within the same delay. The importance of correct handling of tissue specimens and adequate informations to the microbiologist are emphasized. Another point of interest is that good clinical results can be expected from prolonged antibiotic treatment. Surgery must be reserved for diagnosis if no other means has been effective, for failure of medical treatment or for acute complications.

Actinomycosis↗
PubMed1992

[A hypervascular adrenal adenoma. A differential diagnostic problem in dynamic CT and MRT].

At dynamic CT, Gd-DTPA-enhanced MRI, and digital subtraction angiography, a large adrenal adenoma verified by resection histology presented as a hypervascular tumor. In all imaging modalities, it showed a strong patchy enhancement during the early phases of the passage of contrast media and subsequent intralesional contrast equilibration. This case demonstrates that even high enhancement does not rule out an adrenal adenoma with certainty. In the oncologic patient, therapeutic decisions should not be made on the basis of the contrast behavior of an adrenal lesion alone.

Adenoma↗
PubMed1992

Osteosarcoma of the nude rat. A model for experimental magnetic resonance imaging studies of bone tumors.

A 144cerium-induced osteosarcoma was transplanted to athymic nude rats (Han:rnu/rnu). Nineteen of the tumor-bearing animals were used to demonstrate the characteristics of the osteosarcoma on magnetic resonance imaging (MRI) in comparison with a group of nine animals that had not received any tumor transplant. The tumor-free animals showed homogeneous results in the measurements of their lower legs (T1, 800-898 mseconds; T2, 33-45 mseconds). The osteosarcomas of the tumor-bearing rats were clearly demonstrated and delineated from adjacent structures by MRI at tumor volumes between 0.3 and 7.5 cm3. A significant increase in T1 and T2 relaxation times was found, which corresponded to the increase in tumor volume. T1 relaxation times decreased slightly when tumor volumes reached greater than 5 cm3, whereas T2 relaxation times remained constant at tumor volumes greater than 2.5 cm3. Histologic changes in the structure of the tumors, occurring naturally during their growth, were proven by immersion-fixed sections embedded in paraffin and stained with hematoxylin-eosin. The water content of small and large tumors was determined by lyophilization and heat drying. Both histologic changes and differences in water content were reflected in the variations of relaxation times.

Animals↗
PubMed1991

Heat shock factor-independent heat control of transcription of the CTT1 gene encoding the cytosolic catalase T of Saccharomyces cerevisiae.

Transcription of the Saccharomyces cerevisiae CTT1 gene encoding the cytosolic catalase T has been previously shown to be derepressed by nutrient stress. To investigate whether expression of this gene is also affected by other types of stress, the influence of heat shock on CTT1 expression was studied. The results obtained show that expression of the gene is low at 23 degrees C and is induced rapidly at 37 degrees C. By deletion analysis, a promoter element necessary for high level induction by heat shock was located between base pairs -340 and -364 upstream of the translation start codon. This region was demonstrated to be sufficient for heat shock control by placing it upstream of a S. cerevisiae LEU2-lacZ fusion gene. Mutagenesis of the region showed that the response to heat shock is not mediated by a sequence similar to canonical heat shock elements, but by DNA elements also involved in nutrient control of transcription. Catalase T appears to have a function in protecting yeast cells against oxidative damage under stress conditions. Catalase T-containing strains are less sensitive to exposure to 50 degrees C ("lethal heat shock") than isogenic catalase T-deficient mutants, and catalase T-containing strains pretreated by incubation at 37 degrees C are less sensitive to H2O2 than pretreated catalase-deficient mutants.

Base Sequence↗
PubMed1991

Negative regulation of transcription of the Saccharomyces cerevisiae catalase T (CTT1) gene by cAMP is mediated by a positive control element.

Transcription of the CTT1 (catalase T) gene of Saccharomyces cerevisiae is controlled by oxygen via heme, by nutrients via cAMP and by heat shock. Nitrogen limitation triggers a rapid, cycloheximide-insensitive derepression of the gene. Residual derepression in a cAMP-nonresponsive mutant with attenuated protein kinase activity (bcy1 tpk1w tpk2 tpk3) demonstrates the existence of an alternative, cAMP-independent nutrient signaling mechanism. Deletion analysis using CTT1-lacZ fusion genes revealed the contribution of multiple control elements to derepression, not all of which respond to the cAMP signal. A positive promoter element responding to negative control by cAMP was inactivated by deletion of a DNA region between base pairs -340 and -364. Upstream fragments including this element confer negative cAMP control to a LEU2-lacZ fusion gene. Northern analysis of CTT1 expression in the presence or absence of heme, in RAS2+ (high cAMP) and ras2 mutant (low cAMP) strains and in cells grown at low temperature (23 degrees C) and in heat-shocked cells (37 degrees C) shows that CTT1 is only induced to an appreciable extent when at least two of the three factors contributing to its expression (oxidative stress signaled by heme, nutrient starvation (low cAMP) and heat stress) activate the CTT1 promoter.

Base Sequence↗
PubMed1991

Stability of osteochondral fragments of the femoral condyle: magnetic resonance imaging with histopathologic correlation in an animal model.

The stability of surgically induced osteochondral fragments of the femoral condyle was examined by magnetic resonance imaging (MRI) using T1- and T2-weighted spin echo sequences in 7 dogs; contrast-enhanced T1-weighted spin-echo sequences were also obtained. Animals were sacrificed between the 34th and 196th day after surgery. MR images were compared with the histopathologic findings. Two loose and five stable fragments were found after injection of contrast medium. With the loose fragments, a well-defined line of high signal intensity between the fragment and the epiphysis showed marked enhancement. Histological examination revealed vascularized granulation tissue at the interface. Stable fragments also showed a similar, but irregularly defined line on plain sequences, but no enhancement after injection of contrast medium; histological examination showed no granulation tissue at the interface but intact bone trabeculae within the completely repaired fracture. Fibrocartilaginous repair at the articular cartilage surface also showed enhancement. Contrast-enhanced MR imaging allowed an exact delineation of the line of separation of unstable osteochondral fragments in this animal model with differentiation from a similar line occurring in stable fragments. However, this interface line in relation to stable fragments could not be explained histologically and probably reflects differences of binding or distribution of protons in healing osteochondral fragments.

Animals↗
PubMed1991

MR-anatomy of infants hip: comparison to anatomical preparations.

The correlation between anatomical preparations and MRI images of the most important structures of newborn hips in coronal and axial orientation was performed in 18 post mortem babies. T1-weighted images present a good differentiation between cartilage, bone, ligaments and surrounding soft tissues. Coronal images give the best opportunity to study the clinically important structures of the roof of acetabulum including the labrum and the ground of the acetabulum. The latter is shown in a more detailed way by MRI than by sonography. Axial images allow additional examinations of the ventral and dorsal parts of the joint. By using both coronal and axial images the exact determination of the centering of the femur head in the hip joint is possible.

Acetabulum↗
PubMed1991

A bidesmosidic triterpenoid saponin from Schefflera octophylla.

A new 3,28-bidesmosidic triterpenoid saponin was isolated from the leaves of Schefflera octophylla together with a new trisaccharide and oleanonic acid. Based on spectroscopic data and chemical transformations, the structures of the new constituents were determined as 3-epi-betulinic acid 3-O-beta-D-glucopyranoside 28-O-[alpha-L-rhamnopyranosyl(1----4)-O-beta-D-glucopyranosyl(1----6)]-b eta- D-glucopyranoside and alpha-L-rhamnopyranosyl(1----4)-O-beta-D-glucopyranosyl(1----6)-beta-D- glucopyranose.

Carbohydrate Sequence↗