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Biomedical subjects

R Lotz

Publications and source records attributed to R Lotz.

12 recordsLinked to original sources
PubMed1997

Determination of naphthodianthrones in plant extracts from Hypericum perforatum L. by liquid chromatography-electrospray mass spectrometry.

The determination of the naphthodianthrone constituents in extracts of dried blossoms of Hypericum perforatum L. by combined HPLC-electrospray mass spectrometry is described. Hypericin (1), pseudohypericin (2) and their precursor compounds produce intensive negative quasi-molecular ions by deprotonation provided a non-acidic eluent system is used in the HPLC separation. From the [M-H]- ions formed in the electrospray ionization process characteristic daughter ion spectra can be obtained by collisional activation which have been studied by tandem mass spectrometry.

Anthracenes↗
PubMed1997

Elucidation of phase I and phase II metabolic pathways of rhein: species differences and their potential relevance.

Because of previously observed species differences in rhein tolerability, with rabbits being very susceptible to kidney disturbances, in vivo and in vitro biotransformation studies were performed to find out whether the differences in the undesired effects of rhein are associated with qualitative, species-dependent differences in its metabolism. First hints on species-dependent biotransformation profiles were obtained from in vivo experiments with 14C-labeled rhein in rat, rabbit, dog, and man. TLC-analysis of urine samples obtained after oral administration of 14C-rhein to rabbits revealed an additional, hydrophilic metabolite fraction in rabbit urine as compared with dog and human urine, all of which contain phenolic monoglucuronide and monosulfate as major metabolites. An investigation of urine samples (obtained from dogs, rabbits, rats, and human volunteers after oral application of unlabeled rhein) was conducted by means of mass spectrometric tandem techniques including on-line HPLC-MS/MS. In vitro experiments with subcellular liver fractions of rats and rabbits revealed the presence of three monohydroxylated metabolites of rhein, their quinoid oxidation products, and a bishydroxylated derivative of rhein. The hydroxylated phase I metabolites were detected as glucuronides in urine samples of all investigated species, whereas the quinoid product was present only in rabbit urine. Moreover, two regioisomeric phenolic glucuronides and sulfates or glucosides of rhein were found as major phase II metabolites in urine of all species. Furthermore, acyl glucuronides of rhein and monohydroxylated rhein and their respective isomeric acyl migration products were identified in human urine. In rabbit urine we discovered different bisglucuronides (bisphenolic glucuronide, mixed ether/ ester glucuronides), whereas in rats only the bisether/ether glucuronide was present. In addition, the investigations of dog and human urine showed the formation of two regioisomeric phenolic glucosides. With respect to a potential reactivity with endogenous macromolecules the quinoid metabolites as well as the bisester/ether glucuronides appear most relevant.

Animals↗
PubMed1990

[Radiotherapy in HIV positive patients].

HIV-positive Patients often suffer from the symptoms of accompanying diseases. Palliative radiation therapy of associated tumors leads to an improvement of the patient's condition. Particularly skin tumors, which give rise to pronounced itching and ulcerating, are eliminated fast and safe by radiation therapy. Between 1984 and 1988, 6 HIV patients with Kaposi's sarcoma at different sites, and one HIV-patient with non-Hodgkin's lymphoma were treated by radiation therapy. Depending on tumor site, photons or fast electrons were used. Cosmetic results were satisfying or even excellent in all patients. With one exception complete local tumor control was obtained. Side effects leading to a peace of treatment did not occur.

Combined Modality Therapy↗
PubMed1989

[Duplex sonography of the portal vein. Procedure in healthy probands and patients with portal hypertension].

Duplex ultrasonography is a useful non-invasive means of investigating portal vein blood flow in cases of liver disease. A group of 50 selected consecutive patients with portal hypertension revealed a significant increase in portal vein diameter of 3.5 mm on average, and a significant decrease in mean flow rate of, on average, 3.1 cm/s, in comparison with a group of 50 healthy control subjects. In contrast, alcohol-induced portal hypertension appeared always to be associated with an elevated flow rate. On average, the flow volume increased by 200 ml/min. With the exception of vessel diameter, which remains virtually unchanged, both patients and controls revealed, postprandially, a comparable increase in the parameters measured.

Blood Flow Velocity↗
PubMed1987

[Duplex sonography of the normal portal vein].

In 50 normal subjects flow velocity and direction on the portal vein was measured by ultrasonic duplex system. The measurements revealed at a mean diameter of 9.7 mm, a mean flow velocity of 15.2 +/- 2.6 cm/s, corresponding to a volume flow of 693 +/- 235 ml/min. Postprandially this increased to 880 +/- 269 ml/min. Inter-observer and day to day measurements demonstrated good reproducibility. Thus, this simple non-invasive method is well suited for quantitative assessment of the portal vein system in portal hypertension, thrombosis or after shunt operations.

Adult↗
PubMed1987

[Inadequate configurational stability of a DSA pigtail catheter as a cause of complications. Case report and study of the mechanism].

There have been few descriptions extravasation into the superior vena cava and right atrium during intravenous DSA. This is seen almost exclusively when using straight catheters. The configuration of pigtail DSA catheters should reduce or prevent damage to vessel wall due to extravasation. Following an extravasation into the right atrium, which we ascribed to inadequate stability of the distal end of the pigtail catheter, we carried out in vitro experiments with seven DSA catheters from a variety of manufacturers, using an atrial model. Three of these catheters behaved in a manner that would be liable to produce extravasation.

Catheterization↗
PubMed1987

[Tumor invasion of the vena cava inferior in adrenal carcinomas. The preoperative diagnosis].

Tumour invasion of the inferior vena cava from an adrenal carcinoma is not a contraindication to surgical treatment. Pre-operative recognition of the situation is of considerable importance for planning the surgical procedure. Three patients with primary adrenal carcinomas are reported, in whom tumour in the cava was demonstrated by real time and duplex sonography. Sonography proved superior to CT in these cases.

Adrenal Gland Neoplasms↗
PubMed1987

[Duplex sonography of abdominal vessels].

Duplex sonography is a non-invasive procedure which permits the determination of flow velocity and direction in visceral vessels. Results in 50 normals have shown that small arteries can be evaluated in about 50% of cases. The portal venous system can be demonstrated in all cases; average flow velocity and volume is 15.2 +/- 2.8 cm/s and 694 +/- 230 ml/min, corresponding with the values obtained by invasive methods. Clinical application for duplex examinations can be found in portal hypertension, varices, thromboses, aneurysms and transplant kidneys.

Abdomen↗
PubMed1986

[Calcinosis of the supraspinal ligament--a rare secondary finding].

The supraspinal ligament calcification of thoracic spine is a rare roentgenographic finding. If this calcificated ligament is fractured several times it may be possible to misinterpret it as rib serial fractures, if it is overshadowed by dorsal ribs in the side projection of thorax. According to Resnick (4) such a ligamentous calcification is found within the overall framework of the "DISH"-syndrome.

Aged↗