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Biomedical subjects

G Sommer

Publications and source records attributed to G Sommer.

At least 19 recordsLinked to original sources
PubMed1992

Normal renal blood flow measurement using phase-contrast cine magnetic resonance imaging.

RATIONALE AND OBJECTIVES: This study assesses the ability of a cardiac-gated phase-contrast magnetic resonance imaging (MRI) technique to measure renal blood flow (RBF) noninvasively in humans. METHODS: In nine normal volunteers, total RBF in the renal arteries and in the left renal vein was estimated by MRI and correlated with RBF determined by the clearance of para-aminohippuric acid (CPAH) and the hematocrit level. RESULTS: Correlation of RBF estimated from left renal vein flow, with RBF by CPAH-hematocrit, yielded r = .86 (P less than .003). Repeated measurement of RBF by MRI demonstrated a high degree of reproducibility, with coefficients of variation ranging from 4.8% to 8.9%. However, the MRI measurements of arterial flow did not significantly correlate with the standard measurements. CONCLUSIONS: Reproducible noninvasive measurement of normal RBF is possible with the phase-contrast MRI technique used to measure renal venous blood flow.

Adult↗
PubMed1991

In vitro proton spectroscopy of normal and abnormal prostate.

Previous biochemical and 13C NMR spectroscopic data have suggested that the metabolism of citrate, a secretory product of normal prostate, may be interrupted in prostate cancer. In the present study in vitro 1H NMR spectroscopy was used to see if cell strains derived from prostate cancers could be reliably distinguished from those of normal prostate epithelium. High-resolution one-dimensional and two-dimensional J-resolved 1H NMR spectra as well as gas chromatography coupled with mass spectroscopy were used to study extracts of highly defined cell strains from normal peripheral zone, normal central zone, adenocarcinoma, and benign prostatic hyperplasia. Resonances assigned to citric acid and related metabolites were identified. Cell strains derived from prostate cancers tended to have smaller amounts of citrate than those from normal prostate epithelium. However, the differences were small and not statistically significant. The lack of statistically significant differences may reflect the variability present in both normal and abnormal cell strains and thus underscore the well-known difficulty in differentiating normal and cancerous tissues.

Adenocarcinoma↗
PubMed1990

Differential therapy with calcium antagonists in pulmonary hypertension secondary to COPD. Hemodynamic effects of nifedipine, diltiazem, and verapamil.

In 53 patients with COPD and precapillary pulmonary hypertension, we investigated the effect of three typical calcium antagonists on hemodynamics at rest and during bicycle ergometer exercise. In the responders, the decrease in pulmonary vascular resistance following nifedipine was 23 percent at rest (p less than 0.0005) and 35 percent during exercise (p less than 0.0005); following diltiazem, it was 10 percent at rest (p less than 0.05) and 23 percent during exercise (p less than 0.025); following verapamil, it was 22 percent at rest (p less than 0.005) and 11 percent during exercise (p less than 0.025). The cardiac index rose significantly at rest and under exercise only after the administration of nifedipine (+16 percent and +8 percent, resp). Nifedipine caused the most distinctive peripheral vasodilation. The heart rate increased slightly following nifedipine and decreased slightly following diltiazem and verapamil. After long-term therapy with nifedipine (13 +/- 5 months), the decrease in pulmonary artery pressure and pulmonary vascular resistance was no longer significant. In our opinion, the different hemodynamic action profiles will have consequences for the differential therapy in patients with COPD and pulmonary hypertension.

Calcium Channel Blockers↗
PubMed1990

A species and organ specific glomerular basement membrane antigen.

By the use of a monoclonal antibody reacting with the human glomerular basement membrane exclusively we have been isolating a specific glomerular antigen. The antibody failed to react with other renal structures and other basement membranes and extracellular matrix constituents of other organs or plasma proteins. It did not react with glomerular basement membranes of other species as mice and rats. For the isolation of the antigen we applied affinity chromatography, on Sepharose beads coupled to the monoclonal antibody PM II 34 G3. From this column the antigen was eluted under acid conditions. In 8% polyacrylamide gel electrophoresis the approximate molecular weight was estimated with 14400 daltons, which was confirmed on high pressure liquid chromatography using the Bio-Sil TSK method. The antigen was temperature sensitive in that at high temperatures (60 degrees C) several bands on SDS-PAGE and several peaks on HPLC could be noted. This could be responsible for the crystal formation after treatment/concentration on the rotary vacuum pump at 60 degrees C. Preliminary data of amino acid analysis showed a high glycine content pointing towards a collageneous molecule. But cross reactivity with many connective tissue proteins could be ruled out by immuno-histochemical techniques and affinity chromatography. A major point of interest is that this antigen can be detected in human urine under physiological conditions. We are herewith reporting the first species and organ specific glomerular basement membrane antigen.

Amino Acids↗
PubMed1989

Portal venous blood flow in cystic fibrosis: assessment by Duplex Doppler sonography.

Changes of portal venous hemodynamics were investigated in 32 patients with cystic fibrosis (CF) with a mean age of 11.6 years. Hepatic profile of these patients included total bilirubin and albumin together with determination of size and echogenicity of the liver and spleen, determination of the diameter of the portal vein by real-time sonography and quantitation of flow volume of the portal vein using Duplex Doppler sonography. As a control, 35 age matched healthy children were also examined. Diameter of the portal vein was significantly increased in CF patients versus controls. Comparison of the mean flow volume of the portal vein showed a significant increase in CF-patients over 12 y old versus controls. In patients less than 12 y no significant difference of flow volume of the portal vein between CF-patients and controls was noted. The increase of diameter and flow volume of the portal vein suggest an adaptive mechanism in the pressure-volume relationship of the portal venous system in patients with CF.

Adolescent↗
PubMed1989

pH-controlled continuous cultivation of mycoplasmas.

The continuous cultivation of mycoplasmas in a pH-controlled metabolistat was investigated with the fermentative strain Mycoplasma mobile 163K and the nonfermentative strain Mycoplasma arthritidis ISR1. The addition of medium and the removal of culture suspension were regulated by acid production from glucose by M. mobile 163K and by ammonium production from arginine by M. arthritidis ISR1, respectively. For both strains the optimal pH for continuous growth was 7.0. The steady state could be maintained for at least 21 days. With CFU of 8.4 X 10(9) ml-1 (M. mobile 163K) and 3.2 X 10(9) ml-1 (M. arthritidis ISR1), the cell concentrations were slightly higher than those obtained in batch cultures. The dependence on the adjusted pH values was measured for several parameters, such as flow rate, CFU, glucose fermentation or production of ammonia, and gliding velocity. Since the long lag phases of batch cultures can be avoided, pH-controlled continuous cultures provide an appropriate system for the production of mycoplasma cells.

Acetates↗
PubMed1989

Hemodynamic significance of the paraumbilical vein in portal hypertension: assessment with duplex US.

Hemodynamic evaluation of portal and umbilical venous flow with duplex ultrasound (US) was performed in 11 patients with cirrhosis of the liver and a large umbilical vein. Two of these patients had hepatofugal flow in the umbilical vein exceeding hepatopetal flow in the portal vein. These two patients had no evidence of esophageal varices and bleeding. The remaining nine patients had esophageal varices. In these patients, the hepatopetal flow in the portal vein exceeded the hepatofugal flow through the umbilical vein. The authors conclude that duplex US may help identify the massive hepatofugal flow through a large umbilical vein that may reduce the likelihood of esophageal varices and variceal bleeding.

Adult↗
PubMed1988

Prognostic value of supine scintigraphic heart function and simultaneous conventional exercise response in patients after myocardial infarction.

A total of 240 survivors of one or more myocardial infarctions were consecutively admitted to perform supine exercise radionuclide ventriculography. Within 3 years after the test, 22 died; this group was compared to an age-matched control group of 22 survivors for left and right ventricular function during rest, exercise, and simultaneously assessed exercise performance as well as ECG variables. Evaluation of 3-year survival by linear discriminant analysis revealed an accuracy of 82% for discriminant models using ECG and exercise performance variables. Implementation of resting left ventricular ejection fraction and change of right ventricular ejection fraction during exercise, as well as scintigraphic presence or absence of dyskinesia, improved the accuracy of the model to 91% of correctly classified patients.

Adult↗
PubMed1988

Radionuclide detection of mild valvular regurgitation: its significance as assessed by Doppler sonography.

Radionuclide ventriculography (RNV) indices of regurgitation, Fourier amplitude ratio (FAR) and additional RNV variables were prospectively compared to Doppler echocardiography (DE) in 108 consecutive patients with no or mild left ventricular regurgitation, to assess RNV accuracy in detecting regurgitation in patients with different cardiac disorders. Exclusion of left ventricular or tricuspid regurgitation allowed investigation of the FAR range at rest and during exercise in a sufficiently large appropriate reference group without regurgitation. FAR, as well as other RNV variables, failed to provide more information for the diagnosis of mild (clinically irrelevant) left ventricular regurgitation than the diagnosis upon admission alone. Despite the superiority of DE as a gold standard in the detection of mild regurgitation, at present evaluation of RNV regurgitation indices might be the only method to discover regurgitation arising during dynamic exercise.

Echocardiography↗
PubMed1988

Influence of fluid replacement on extravascular lung water (EVLW) in patients with diabetic ketoacidosis.

Fluid replacement is a major issue in the treatment of patients with diabetic ketoacidosis. During this therapy, development of pulmonary edema has been reported and attributed to an increase in pulmonary microvascular pressure and a decrease in colloid-osmotic pressure (COP). Because clinically apparent pulmonary edema is associated with an increase in extravascular lung water (EVLW) and impairment of pulmonary gas exchange, we studied the effect of fluid replacement on EVLW, COP, pulmonary hemodynamics and gas exchange parameters in 8 patients with diabetic ketoacidosis (blood glucose greater than 300 mg/dl, pH less than 7.1). EVLW was estimated by the thermal-dye technique. All variables were successively determined upon admission (A), after initial fluid replacement (IFR), when glucose had fallen below 180 mg/dl, after 8 h of intravenous glucose treatment (G), and after 24 h of total parenteral nutrition (TPN). Despite a total net fluid intake of 6.0 +/- 1.61, a significant decrease (p less than 0.001) in COP from 29.6 +/- 5.5 at A to 18.8 +/- 2.2 mmHg after TPE and a significant increase (p less than 0.001) in PCWP from 4 +/- 2 at A to 10 +/- 3 mmHg after TPE, EVLW remained almost unchanged. EVLW was 5.1 +/- 2.8 at A, 5.3 +/- 2.1 after IFR, 4.8 +/- 1.4 after G, and 5.3 +/- 1.7 ml/kg after TPN. However, PaO2 decreased from 137 +/- 17 at A to 87 +/- 10 mmHg after TPE (p less than 0.001), while Qs/Qt increased significantly (p less than 0.05). The alterations in gas exchange may be indicative of pulmonary dysfunction but as they were not associated with accumulation of EVLW, they may as well reflect the compensation of metabolic derangements in diabetic ketoacidosis.

Adult↗
PubMed1988

Noise-reduced prostatic MR imaging. Work in progress.

Measurement-dependent filtering, a nonlinear noise-reduction technique, was used to improve the signal-to-noise ratio of in vivo T2-weighted magnetic resonance images of the prostate gland. In both normal and abnormal prostates, the technique considerably reduced noise in T2-weighted images. The technique may provide more accurate depiction of regions of benign prostatic hyperplasia and carcinoma in the prostate.

Filtration↗
PubMed1987

Accessory spleen: presentation as a large abdominal mass in an asymptomatic young woman.

Accessory spleen hypertrophy is usually related to hematologic, lymphomatous, and rheumatoid diseases. We describe here the case of an 18-year-old asymptomatic woman who presented with a very large accessory spleen occupying the lower abdomen. Its appearance on abdominal sonogram, computed tomogram, and hepatosplenic scintigraphy is correlated with the resected specimen.

Abdominal Neoplasms↗
PubMed1987

[Differential diagnostic problems of subtotal hepatic steatosis in the sonogram].

The authors describe the appearance of focal sparing in otherwise diffuse fatty infiltration of the liver found in 35 patients. These are pseudotumours which are less echogenic than the surrounding abnormal parenchyma. They are sharply marginated, of triangular shape and show no mass effect--neither by displacement of vessels nor by deformity of the contour of the liver. These characteristic morphologic features allowed a differentiation from neoplasms or abscesses in 80% of our cases. Hence, biopsies are rarely indicated in these patients.

Adult↗