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Biomedical subjects

G Mueller

Publications and source records attributed to G Mueller.

At least 55 records · Page 3Linked to original sources
PubMed1990

Labyrinth learning impairment in patients with early symptoms of presenile dementia.

21 patients (54 +/- 7 years old) with early cognitive deficit (ECD) during the presenile stage of presumptive primary degenerative dementia (mild stage) and 14 patients (54 +/- 4 years old) with early cognitive deficit with a background of cardiovascular disease (CVD) were examined in a labyrinth learning test of Milner (modified by Roth). 15 patients in the ECD group made 3 times more errors to negative fields (p less than 0.01), about 10 times more errors to positive fields (p less than 0.01) and needed treble the amount of time for passing through the labyrinth (p less than 0.01) compared with a healthy control group (51 +/- 4 years). A further 6 patients of the ECD group had no success in performing the labyrinth test. The CVD group was not different from the control group in making errors, but slower (p less than 0.05). The labyrinth test is found suitable for a more precise diagnosis of early cognitive deficit in the early stage of a primary degenerative dementia of the Alzheimer type.

Cognition Disorders↗
PubMed1988

Transforming growth factor beta as a potent promoter in two-stage BALB/c 3T3 cell transformation.

We have tested transforming growth factor beta (TGF beta) in the two-stage BALB/c 3T3 cell transformation assay for possible tumor-promoting activity, since it has several effects similar to those of tumor-promoting phorbol esters. After initiation of BALB/c 3T3 cells with 3-methylchol-anthrene, treatment with TGF beta at 1 ng/ml alone or in combination with epidermal growth factor (EGF) for 4 weeks enhanced the number of transformed foci by 5- to 6-fold in comparison with uninitiated cells. Initiation treatment alone induced no or very few transformed foci in several assays. Treatment with phorbol-12,13-didecanoate (PDD) at 100 ng/ml for 4 weeks enhanced the number of transformed foci in initiated BALB/c 3T3 cells by 4- to 5-fold in comparison with uninitiated cells. Thus, TGF beta at 1 ng/ml is as potent as PDD at 100 ng/ml for tumor-promoting activity in the two-stage BALB/c 3T3 cell transformation assay. The enhancing effect of TGF beta was dose-related in the dose range tested (0.03-1 ng/ml) and was not reversible. Some of the foci induced by combined MCA-TGF beta-EGF treatment were cloned, and eight out of nine clones tested produced tumors in nude mice. TGF beta (1 ng/ml) plus EGF (2 ng/ml) increased the saturation density to a similar extent as PDD (100 ng/ml) but did not affect the growth of BALB/c 3T3 cells. We observed no change in junctional intercellular communication, as measured by the dye transfer method, when cells were treated with TGF beta during the two-stage BALB/c 3T3 cell transformation assay. Nevertheless, there was selective communication between transformed and surrounding nontransformed cells; MCA-TGF beta transformed cells intercommunicated among themselves but not with surrounding nontransformed cells. Our results indicate that TGF beta has potent tumor-promoting activity in vitro, but that this activity is not mediated by a complete blockage of intercellular communication, as is suggested for phorbol ester tumor promoters.

Animals↗
PubMed1985

Surgical approach and review of literature on gastroduodenal aneurysm: a case report.

Splanchnic artery aneurysms are relatively uncommon occurrences. The splenic artery aneurysm is the most common, making up 58% of the abdominal visceral vessel aneurysms. This is followed by hepatic artery aneurysm and those of the gastroduodenal (GDA) and pancreaticoduodenal arteries. The GDA artery aneurysm is quite rare. Only 29 had been reported by 1980. We are reporting here a case of GDA aneurysm diagnosed pre-operatively as an aortic aneurysm. We will also review the literature and make note of the changes in pathophysiologic concepts and the diagnosis of GDA aneurysms.

Aged↗
PubMed1983

Comparative functional properties of mitochondria from seal and dog hearts.

The harbor seal (Phoca vitulina) is capable of protracted dives resulting in low arterial PO2 levels. The mammalian heart is an aerobic organ depending primarily on mitochondrial oxidations for energy (ATP). Heart mitochondria were isolated from freshly killed seals and the functional data obtained compared to dog heart mitochondria isolated under similar conditions. The percentage yields of mitochondria based on cytochrome oxidase recovery were essentially the same from dog and seal hearts. However, the actual quantity of mitochondrial protein obtained per gram of seal heart tissue was lower than that isolated from dog heart. Phosphorylating rates of respiration (State 3; Q02) and cytochrome content were significantly lower in seal heart mitochondria compared to dog. The data indicate that seal hearts have fewer mitochondria per gram of tissue, lower active respiratory rates and lower cytochrome contents than dog heart.

Animals↗
PubMed1983

Effect of tinnitus masker noise on speech discrimination in quiet and two noise backgrounds.

Use of masking devices is achieving recognition as a means of providing tinnitus relief. While palliative results have been described, possible disruptive consequences have not yet received attention. The present study examined the effects of tinnitus masker noise on speech intelligibility. Twenty young normals listened to NU-6 word lists presented in sound field in quiet white noise, and cocktail party noise backgrounds (S/N = O dB) with and without a tinnitus masker. Although there was little impairment while wearing the masker in quiet, substantial discrimination loss was observed in the two noise backgrounds. The potential disruption in communication function while wearing a masking device is discussed.

Adult↗
PubMed1983

Effects of neocarzinostatin on chromatin in HeLa S3 nuclei.

Neocarzinostatin solubilizes chromatin from HeLa S3 nuclei by introducing strand scissions in linker regions. Multimeric nucleosome patterns are seen on both native and denaturing gel analysis. The mechanism of drug action differs from the type of chromatin digestion seen with micrococcal enzyme in that DNA damage occurs through single-strand breaks and less acid-soluble material is produced. In addition, drug-induced release of soluble chromatin from the nuclei is not very dependent upon the addition of EDTA. The monomer repeat size is larger than that found for micrococcal enzyme and contains linker regions that are partially single-stranded. Core histone proteins as well as histone H1 do not appear to be altered by drug action, although there is clear evidence that DNA damage can occur in nucleosome cores. The chromophore portion of the drug degrades chromatin as effectively as the holoantibiotic.

Antibiotics, Antineoplastic↗
PubMed1983

The effects of the antitumor protein auromomycin on HeLa S3 nuclei. Release of soluble chromatin.

The protein antitumor agent auromomycin releases chromatin from intact HeLa S3 nuclei by introducing strand scissions in DNA linker regions. The ability of auromomycin to solubilize nuclear chromatin was compared with the well-characterized action of micrococcal nuclease. Production of acid-soluble material (DNA 10-20 base pairs or less) did not increase significantly over a range of drug levels or incubation times. Release of chromatin from auromomycin-treated nuclei was not affected by EDTA but required dithiothreitol for optimal activity. The soluble chromatin, when resolved by agarose gel electrophoresis, consisted of discrete nucleosome bands ranging from monomer to hexamer size and unresolved higher molecular weight oligomers. Sufficiently high concentrations of drug convert most of the higher molecular weight oligonucleosomes to dimer and monomer material. These nucleosome bands were quite broad and could indicate strand scission occurring at random throughout the linker region. The average size of the drug-generated mononucleosomes from multiple experiments was 175 +/- 4 base pairs. In contrast to micrococcal nuclease, higher concentrations of drug did not degrade mononucleosomes to core particles. Solubilized chromatin is detectable following drug treatments as short as 5 min. Chromatin produced at early time points was mostly small and very heterogeneous. Chromatin from drug-digested nuclei analyzed under denaturing conditions appeared as discrete bands similar to those observed on native gels. The ratio of single- to double-stranded breaks may be close to 2:1. When chromophore isolated from the holantibiotic was incubated with nuclei, a similar pattern of chromatin degradation was observed.

Anti-Bacterial Agents↗
PubMed1983

Tomoscintigraphic assessment of myocardial metabolic heterogenity.

I-123-omega-heptadecanoic acid (HDA) was evaluated for myocardial scanning in 59 healthy volunteers and 133 patients, using a 7-pinhole collimator. Early (uptake) and late (retention) images were compared visually. Regional HDA elimination was also followed semiquantitatively based on the calculation of a retention-over-uptake ratio, R(phi), derived from the maximal counts/pixel in 60 midventricular slice sectors. The healthy heart concentrated HDA homogeneously in all segments with no difference between early and late images. The minimal R(phi), taken as representative of that myocardium with the best function, was unchanged after maximal ergometer stress and with dipyramidole-induced hyperperfusion. A circumscribed decreased HDA uptake is the clear-cut criterion for an abnormal finding. HDA tomography of the myocardium had an 86% sensitivity for myocardial infarcts (MIs) up to 4 wk old, and 83% for myocardial scars (MSs). Comparing early and late tomograms, we find a cool-warm sequence more often with acute and subacute MIs. A cool-cool or a cold-cold sequence dominated with MSs. HDA tomoscintigraphy cannot replace TI-201 for the evaluation of regional coronary reserve in coronary heart disease.

Adult↗
PubMed1980

Somatic cell genetic analysis of regulation of expression of 3-hydroxy-3-methylglutaryl-coenzyme A reductase.

Three new types of regulatory somatic cell mutants defective in expression of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase are described. They include a recessive mutant with abnormally high enzyme activity, apparently defective in degradation of the enzyme, and one, phenotypically a mevalonate auxotroph, that maintains permanently repressed levels of enzyme activity and are recessive, constitutive mutants. These mutants offer means for analyses of the mechanism of regulation of expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase in cultured fibroblasts.

Animals↗
PubMed1978

Plasma protein binding of valproic acid in healthy subjects and in patients with renal disease.

1 Based on the Scatchard plot of the binding data of valproic acid (VPA) it is concluded that the drug is bound by two groups of binding sites with the association constants K1=40.0 X 10(-3) and K2=0.39 X 10(3), and the number of binding sites n1=1.5 and n2=6.8. 2 The binding is dependent on dialysis time, on temperature, on the drug concentration, and on the protein concentration in plasma. 3 At therapeutic plasma concentrations unbound VPA is 8.4 +/- 2.5%, but is increased to 20.3 +/- 4.7% in patients with significant impairment of renal function (P less than 0.001). 4 In patients with renal disease a good correlation is found between unbound VPA and serum creatinine, creatinine clearance, blood nitrogen and uric acid, respectively. A poor correlation is seen between unbound VPA and total protein or albumin concentration in plasma.

Binding Sites↗
PubMed1975

Thyroid state and brain monoamine metabolism.

The rates at which rat brain synthesizes catecholamines and serotonin were estimated by measuring the accumulation of DOPA and 5-hydroxytryptophan (5-HTP) 45 min after ip administration of the decarboxylase inhibitor RO4-4602 (800 mg/kg BW). Following thyroparathy-roidectomy, hypothyroid rats showed a decreased accumulation of both precursor amino acids. On the other hand, hyperthyroidism (caused by administering 15 mug T4/100 g BW for 25 days) accelerated the accumulation of catecholamines and serotonin. The accumulation of 5-HTP correlated closely with brain tryptophan concentration in all treatment groups; DOPA accumulation, however, did not similarly correspond to brain tyrosine levels.

5-Hydroxytryptophan↗