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Biomedical subjects

D Matthaei

Publications and source records attributed to D Matthaei.

At least 37 records · Page 2Linked to original sources
PubMed1986

Multiple chemical shift selective (CHESS) MR imaging using stimulated echoes.

Recently, stimulated echo acquisition mode (STEAM) magnetic resonance (MR) imaging has been demonstrated as a new tool for multiparametric MR imaging studies. Applications of the chemical shift selective (CHESS) STEAM technique using a 2.0-T whole-body MR imaging system are reported in which a series of contiguous cross-sectional images of the head and the pelvis were acquired. Because selective excitation of the desired component is employed rather than elimination of the unwanted component, this method yields an improved degree of spectral resolution which is dependent only on the homogeneity of the static magnetic field. For routine medical applications, no sophisticated adjustment of the CHESS pulse is needed, as reported in previous methods.

Adipose Tissue↗
PubMed1985

Gas chromatography of amino acids in urine and haemofiltrate.

Capillary gas chromatography of amino acid derivatives obtained from biological material shows a large number of previously unknown constituents. The profiles of amino acids obtained from urine of healthy individuals and haemofiltrate of uraemic patients indicate that haemofiltration removes some amino acids to a considerably higher extent from uraemic patients than the kidney does from healthy persons. For instance, if haemofiltration is required three times a week, an approximately ten-fold amount of the essential amino acid methionine and a forty-fold amount of the essential amino acid leucine is lost compared to their excretion in urine by a healthy individual over the same period.

Amino Acids↗
PubMed1985

Chemical-shift-selective magnetic-resonance imaging of avascular necrosis of the femoral head.

Chemical-shift-selective (CHESS) nuclear-magnetic-resonance (NMR) imaging is a new method for separating "water" and "fat" (CH2) resonances in proton NMR imaging. Its major advantage over conventional composite NMR imaging is the contrast enhancement, which in particular allows the detection of small water-containing structures, such as vessels or joint surfaces, normally obscured by fat signals. First clinical findings in the femoral head with avascular necrosis are reported.

Adipose Tissue↗
PubMed1985

Chemical shift selective MR imaging using a whole-body magnet.

We have applied a new method for separating water and fat resonances in proton magnetic resonance (MR) imaging to human studies using a whole-body MR imaging system at 2.0 T. Chemical shift selective (CHESS) MR imaging provides either a water or fat image in a single experimental run within the same time needed for a conventional composite image. Although the technique requires a spectral resolution of about 1 ppm over the entire imaging region, first images of the human head and hip indicated that CHESS MR imaging is extremely promising for use in clinical investigations. Moreover, CHESS MR imaging can be combined arbitrarily with other imaging modalities and is easy to implement in any high-field MR imaging system.

Adipose Tissue↗
PubMed1983

Influence of insulin on blood levels of branched chain keto and amino acids in man.

Branched chain keto acids, their corresponding amino acids, glucose, glucagon, growth hormone, C-peptide and gastric inhibitory polypeptide were determined in 8 healthy subjects after an intravenous bolus injection of 0.1 U/kg insulin. Branched chain keto acids declined within 60 min, the corresponding amino acids within 20 min or later. Amino acids tended to return towards normal earlier than their keto acids. Blood glucose levels were normal 2 hr after insulin injection while keto and amino acids remained diminished for more than 3 hr. In 8 healthy controls, given physiological saline instead of insulin, the branched chain keto acids did not decline throughout the test. It is suggested that insulin diminishes blood levels of branched chain keto acids, that the intraorgan flux of branched chain keto acids is different from the flux of branched chain amino acids and that branched chain keto acids may serve to correct for hypoglycemia.

Adult↗
PubMed1983

The identification of urinary bile alcohols by gas chromatography-mass spectrometry in patients with liver disease and in healthy individuals.

The neutral steroid fractions in the urine of eleven patients suffering from various forms of liver disease with cholestasis and of ten healthy individuals were studied by glass capillary gas chromatography-mass spectrometry. The steroid conjugates in urine were enzymatically solvolysed, the liberated steroids extracted and transformed into the trimethylsilylether for measurements. The excretion rates of androstane and pregnane metabolites of patients with liver disease were far lower than those of healthy persons. The main compounds in the urine of the former were the bile alcohols 27 - nor - 3 alpha, 7 alpha, 12 alpha, 24 xi, 25 xi - pentahydroxy - 5 beta - cholestane and 3 alpha, 7 alpha, 12 alpha, 25 xi, 26 - pentahydroxy - 5 beta - cholestane. Our data suggest a correlation between the excretion rates of these bile alcohols and the serum levels of bilirubin. While the excretion rate of the two bile alcohols in the urine of healthy individuals was approximately 0.24 mg/24 h (0.6 mumol/24 h) a patient with a serum bilirubin of 841 mumol/l excreted 4 mg/24 h (9 mumol/24 h). The accumulation of bile alcohols described in this study possibly indicates alternative pathways of cholic acid formation in liver disease.

Adult↗
PubMed1982

Analysis of neutral steroid sulfates by glass capillary gas chromatography-mass spectrometry (GC-MS) from blood of a patient with paraquat poisoning.

The chemical analysis of neutral steroid sulfates by glass capillary gas chromatography -mass spectrometry (GC-MS) from the blood of a young girl with acute suicidal paraquat poisoning is described. The steroids had been extracted from an XAD-filter used for immediate hemofiltration treatment of the patient. The steroids analyzed were isomers of known blood and urine components without unusual substituents. It can be concluded that oral intake of paraquat in even large amounts does not cause significant disturbances of steroid metabolism, at least not in the acute state of intoxication.

Adolescent↗
PubMed1981

[Psoriasis and haemodialysis: changes in plasma hormone concentration as a possible therapeutic mechanism (author's transl)].

Free dehydroepiandrosterone (DHEA), DHEA sulphate, testosterone, LH and FSH were measured in plasma from 67 patients with renal disease before and after haemodialysis or haemofiltration. Plasma concentration of the steroid hormones was lower in patients with renal failure than in normal controls, while that of the gonadotrophic hormones was elevated. After haemodialysis or haemofiltration DHEA sulphate level in plasma decreased, free DHEA increased significantly reaching almost the initial value of the control group. There was no change in concentration of the other steroid and gonadotrophic hormones. The likely mechanism is that haemodialysis removes DHEA deficiency in patients with psoriasis which is assumed to be an aetiopathogenetic factor in the disease.

Dehydroepiandrosterone↗
PubMed1981

Blood levels of branched-chain alpha-keto acids in uremia: effect of an oral glucose tolerance test.

The effect of an oral glucose tolerance test (oGTT) on serum levels of branched-chain keto acids (BCKA), i.e. alpha-keto-isocaproic acid (KICA), alpha-keto-isovaleric acid (KIVA) and alpha-keto-beta methyl-n-valeric acid (KMVA) as well as on serum insulin, C-peptide and blood glucose levels was determined in uremic patients and in healthy control subjects. In controls, blood levels of KICA, KMVA and KIVA declined significantly following oral administration of 100 glucose. In uremic patients no decline of KICA was observed. The fall of KMVA was diminished, while suppression of KIVA blood levels in response to the oGGT remained unimpaired. Although serum insulin and C-peptide levels in uremic patients were not significantly different from the controls before and throughout the oGTT, six out of eight displayed abnormal glucose tolerance. It is suggested that the response of blood BCKA levels to an oGTT is altered in uremia, an abnormality restricted primarily to KICA and possibly explained by insulin antagonism and/or by insufficient insulin secretion.

Adult↗
PubMed1981

High resolution gas chromatography mass spectrometry of the methyl esters of organic acids from uremic hemofiltrates.

The organic acid fraction of hemofiltrates was investigated in the form of methylates by glass capillary gas chromatography-mass spectrometry. The pattern obtained is similar to that of urinary organic acid methylates from healthy individuals. A marked difference was noted for N-phenylacetyl-alpha-aminoglutarimide, present in hemofiltrate at levels 50-100 times higher than those in urine. Analysis of hemofiltrate samples taken at different times during a hemofiltration with post-dilution technique revealed that the hemofiltrate concentration of most compounds was drastically reduced the course of the hemofiltration treatment. Compared to the other compounds, the reduction in hemofiltrate concentration of N-phenylacetyl-alpha-aminoglutarimide was extremely rapid.

Adult↗
PubMed1980

[Reno-cardiac interactions in kidney failure (author's transl)].

The high incidence of cardiac complications in endstage renal failure is not only related to the chronic pressure load of the left ventricle, although the proportion of patients with elevated blood pressure increases from 53 to 81% as reno-parenchymal disease progresses. Other factors as anemia, hyperparathyroidism, autonomic neuropathy and retention of electrolytes, metabolic products of toxins may cause damage to the heart. It is a matter of discussion whether uremia itself causes cardiomyopathy. Findings of a reduced Ca++-uptake during beta-adrenergic stimulation and a reduced reaction of (Na+, K+)-ATPase to digitalis suggest a basic change of myocardial membrane metabolism. Retention of an "endogenous digitalis" could help to explain some contradictory results.

Adolescent↗