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Biomedical subjects

W Lotz

Publications and source records attributed to W Lotz.

At least 37 records · Page 2Linked to original sources
PubMed1982

[Improved x-ray diagnosis of stomach by progress in the development of contrast media and examination techniques (author's transl)].

Three factors have been responsible for the advances during the past few years in x-ray examination of the stomach: Improvement of the contrast media used; introduction of the rare-earth foils; and examination techniques imaging all sections of the stomach and of the duodenal bulb under hypotension in double-contrast technique, in complete filling, and imaging the accessible sections by means of proper compression. An interesting technique employs a combination of two different barium sulphate suspension used at the same time, e.g. Bubbly Barium or some other barium sulphate preparation with a small amount of High-Density Barium yielding excellent image of the gastric mucosa (technique with two contrast media).

Barium Sulfate↗
PubMed1981

Blood sampling by chronic cannulation technique for reliable measurements of catecholamines and other hormones in plasma of conscious rats.

An optimalized technique for chronic venous and arterial cannulation of rodents that permits repeated blood collections in unstressed, freely moving animals is presented. The indwelling catheter can also be used for chronic and/or acute drug administration in rats or other small laboratory animals, as well as for the recording of blood pressure and heart rate. The attachment device of minimal size is easily fixed on the head of the animals, allowing the additional implantation of a chronic cannula for intracerebral injections. No residual effects on the resting levels of plasma catecholamines (CA) were present 24-hr after surgery and anesthesia for implanting the cannula. No variations of plasma CA concentrations were observed at the different times of day examined or as a consequence of withdrawal of subsequent blood samples. Training the animals to be handled prevented the increase in plasma prolactin levels produced by decapitation; training had no influence on the decapitation-induced rises in plasma CA concentrations.

Animals↗
PubMed1981

Dihydrotestosterone causes reversible infertility in male rats.

Dihydrotestosterone released continuously from a subcutaneously implanted Silastic elastomer was more potent than testosterone in reducing circulating gonadotropin and androgen concentrations and in inducing testicular atrophy and infertility despite normal ejaculatory function as judged by the presence of vaginal plugs in cage mates. All effects were reversible. Thus quantities of dihydrotestosterone which reduce circulating gonadotropin concentrations suffice to maintain the weights of accessory sex organs but not spermatogenesis. That the latter is possible with higher doses even in the complete absence of luteinizing hormone and follicle-stimulating hormone (state after hypophysectomy) has been shown by others.

Animals↗
PubMed1980

[Areae gastricae and varioliform erosions--the criteria concerning the quality of radiological examinations of the stomach (author's transl)].

Two hundred otherwise unselected patients had barium meal examinations for upper abdominal pain; in 93% of these the areae gastricae could be visualised on more than one third of the gastric surface. In 17%, i.e. 34 patients, varioliform erosions were found; these confirmed by gastroscopy in 11.5%, i.e. 23 patients. Varioliform erosions are a frequent cause of obscure upper abdominal pain or gastro-intestinal haemorrhage. Their diagnosis is therefore of great importance. Regular demonstration of the areae gastricae is associated with an increased ability to show these erosions and must therefore be regarded as a measure of the excellence of a radiological examination of the stomach.

Barium Sulfate↗
PubMed1979

[Improved radiological diagnosis in the stomach by means of an improved contrast material (author's transl)].

Our experience with a cheap contrast medium, which we prepare ourselves, is described, stretching over a period of 18 months. It is based on the bubbly barium first described by Op den Orth and is made by means of carbon dioxide in a soda water syphon. It is better for detailed contrast examination of the stomach than the commercially available contrast media. It is thought that this is due to optimal viscosity for wetting of the mucosa, optimal size of the barium sulphate particles, which are larger than one micron, and greater distension of the stomach due to greater quantities of CO2. The use of bubbly barium for routine examination of the stomach, using double contrast and hypotonia with graded compression, almost always results in demonstration of the areae gastricae in large parts of the stomach. We regard this as a sign of a good examination, since we are then able to demonstrate small lesions such as complete or incomplete erosions, ulcer scars or flat ulcers.

Barium Sulfate↗
PubMed1978

[Scintigraphy for doubtful vertebral fractures (author's transl)].

Fractures, particularly those of vertebral bodies, cannot always be demonstrated radiologically. The use of scintigraphy for this purpose is known but, in our opinion, this is not used sufficiently. Diagnosis of fractures by scintigraphy is almost 100% reliable. In the presence of degenerative changes in the spine, this is frequently the only method for differentiating between old and new fractures. By using the almost universally available substance 99mTc one has a cheap method with virtually no radiation dose. The earliest accumulation of 99mTc-MDP after fracture of a vertebral body was seen four hours after the trauma; absence of uptake three days after trauma excludes a fracture.

Adolescent↗
PubMed1978

Correlation between the effects of neuroleptics on prolactin release, mammary stimulation and the vaginal cycle in rats.

The correlation between hyperprolactinaemia induced by the administration of neuroleptic drugs, disturbances of the vaginal cycle and mammary gland stimulation in rats was investigated as a test model simulating the clinical syndrome of hyperprolactinaemia and amenorrhoea with anovulation. In acute experiments in which clozapine, sulpiride and chlorpromazine were administered orally to rats of both sexes, there were rapid increases in the level of prolactin in the serum with peak values between 15 and 60 min. The responses of female rats to various doses of sulpiride were consistently higher than those of male rats. Hyperprolactinaemia induced by sulpiride in dioestrous rats failed to desensitize the ovaries to the ovulatory effect of exogenous luteinizing hormone releasing hormone. Studies of these substances and of metoclopramide, haloperidol and thioridazine were then carried out in females rats by daily oral administration over a period of 13 days. The increases in the level of prolactin in the serum were paralleled by disruption of the vaginal cycle up to and including constant dioestrus and by mammary gland stimulation which, like the preceding phenomena, showed dose-dependence. The potencies of these six neuroleptics, as estimated from their effects on the mammary gland, appeared to be haloperidol greater than sulpiride greater than or equal to metoclopramide = thioridazine greater than chlorpromazine greater than clozapine.

Animals↗
PubMed1977

Bacteriophage 7-7-1 adsorbs to the complex flagella of Rhizobium lupini H13-3.

Bacteriophage 7-7-1 is shown to adsorb specifically to the complex flagella of its host Rhizobium lupini H13-3. Deflagellation of motile cells before the addition of phage leads to a complete inhibition of phage propagation for at least 60 min. Among phage-resistant mutants, many non-motile (mot) and non-flagellated (fla) derivatives of R. lupini H13-3 have been selected. Electron microscopic observations indicate that bacteriophage 7-7-1 attaches with its short tail fibres to the conspicuous helical filament of R. lupini flagells. This attachment is reversible; irreversible phage adsorption takes place at the flagellar base. It is postulated that phage 7-7-1 moves along the rotating flagellum towards a final receptor next to the insertion site of the flagellum, where tail contraction and injection of phage nucleic acid occurs.

Adsorption↗
PubMed1975

Isolation and characterization of a rod-shaped bacteriocin from a strain of Rhizobium.

A bactericidal agent ('bacteriocin 16-2') produced by rhizobial strain 16-2 had been characterized as a sheathless rod-shaped particle with a length of 200 nm and a diam. of 8 nm. One end of the rod is pointed and carries short fibre-like appendages, while the other end appears square. The particles specifically adsorb with their pointed end to bacteriocin-sensitive, but not to bacteriocin-resistant, cells. The possible mode of action of this bacteriocin in discussed.

Bacteriocins↗
PubMed1975

Attachment of a long-tailed Rhizobium bacteriophage to the pili of its host.

Bacterial strain 16-12 was isolated from the root nodules of lupines and was found to be mitomycin C-inducible for the production of a bacteriophage ("16-12-1") with a long noncontractile tail. The phage was found to attach with a fork-like terminal tail structure to the pili of strain 16-12. In addition, it was also found adsorbed to the bacterial cell poles. It is suggested that phage 16-12-1 may be pilus dependent.

Journal Article↗
PubMed1975

The influence of time, dose and gonadal steroids on LH-RH-induced gonadotrophin release in rats.

Hypophyseal responses to LH-releasing hormone (LH-RH) were studied in ovariectomized rats, pre-treated once with 50 mug oestradiol-3-benzoate alone or in combination with 25 mg progesterone either 16, 24, 48 or 72 h before the administration of LH-RH. The highest serum gonadotrophin increase was detected in ovariectomized rats pre-treated with oestrogen 48 h before the LH-RH injection. The serum LH concentration change in intact male rats was markedly lower in terms of order of magnitude than in ovariectomized, oestradiol-3-benzoate, progesterone-treated rats ("O.Oe. P."-rats). These latter test animals showed the maximal increase of serum LH concentration, depending on the dose of LH-RH, after 10 to 25 min and that of FSH after 40 min. The dose-response curves for LH release in "O.Oe.P."-rats were linear for short (10 and 15 min) and sigmoid for longer time intervals (20, 30 and 40 min) between LH-RH injection and sacrifice. The possible reasons for this difference in both magnitude and time-lapse for maximal increase of serum LH and FSH concentration, the influence of steroid pre-treatment and the variation of the time course of serum LH concentration, depending on the dose of LH-RH, are discussed.

Animals↗