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Biomedical subjects

H D Lehmann

Publications and source records attributed to H D Lehmann.

At least 37 records · Page 2Linked to original sources
PubMed1983

[So-called glomera in the region of the prostate].

In three cases prostate biopsies revealed structures which showed the histological characteristics of so called glomera (chemodectomas), one within the prostatic tissue, the others in the area of the capsule. Clinicians and pathologists to avoid misinterpretation have to be aware of the fact that this wellknown structure can occur in biopsy material.

Humans↗
PubMed1982

Successful in vivo experiments in sheep using a new nonhydrolyzable enzyme reactor resistant against tryptic digestion.

Blockage of E-amino groups of asp-ase bound to cellulose by succinylation results in a greatly enhanced resistance against tryptic digestion by "plasma enzymes." Plasmapheresis in sheep by plasma filters connected to asp-ase Cellulose cartridges led to decrease of asp-NH2 and glut-NH2 in plasma over 21 hrs with undetectable enzyme leakage from the solid phase.

Animals↗
PubMed1981

How to catch urea? Considerations on urea removal from hemofiltrate.

Hemofiltration imitates the first step in the natural function of the kidney. After separation from corpuscular and high molecular weight blood components, a filtrate remains which contains urea together with electrolytes and other low molecular weight metabolites. To use a hemofilter in a recirculating closed-loop system, a big quantity of urea must be eliminated. A survey of published attempts to solve this problem is presented. Reasons are given for the difficulty to eliminate urea directly from dilute aqueous solutions. Explanations for ambiguous results of some reactions proposed for urea removal are discussed. The concept of hard and soft acids and bases is used to develop demands to the structure of a reagent which reacts preferentially with urea in aqueous solution. On monomeric model substances-activated aldehydes-this hypothesis is proven in vitro. In spite of the given technical possibility of urea removal, the authors doubt whether solving the problem of urea removal will enable a closed-loop system for alternative simpler or more economic ways of treating renal failure.

Blood↗
PubMed1981

Urea elimination using a cold activated-carbon artificial tubulus for hemofiltration.

Urea adsorption on active carbon is reversible and temperature-dependent. Urea adsorption isotherms of different carbons were determined at 0 degrees C and 65 degrees C within the equilibrium concentration range of 1.0-3.4 gm/L. At low urea concentrations considerable differences (3.4-13.0 gm/kg carbon at concentrations of 1.0 gm/L) were found between different types of activated carbon. The overall internal surface area was of minor importance compared to the pore size distribution. Adsorbing at low temperature, desorbing at high temperature, and flushing the carbon adsorber with a limited volume of the liquid to be purified yielded an "artificial urine." Compared to the original urea concentration of the filtrate, this "artificial urine" had an increased urea concentration. From a 36-liter volume containing 90 grams urea dissolved in saline, 18 liters were recirculated at a flow rate of 100 ml/min. The influence of adsorption and desorption time intervals was evaluated. After one to one and a half hours the carbon was saturated with urea. After saturation, about 1.4 grams urea were eliminated per cycle. In the "artificial urine" urea concentrations of up to 4.5 gm/L were found when the original solution contained only 2.5 gm/L. In the "patient" volume the urea concentration decreased from 2.5 gm/L to 1.9-2.1 gm/L. Within three hours a total of 22 grams of urea was removed by 3 x 120 grams activated carbon corresponding to removal of 50% of the urea passing the "artificial tubulus." The advantage of this system is that after priming, no additional physiological solution would be necessary. The necessity of excessive safety controls, additional electrolyte adjustment, energy demand in the form of direct current, and great amounts of waste in solid form lead to the conclusion that for intermittent hemofiltration treatment, commercially produced and controlled infusion solution is preferable.

Adsorption↗
PubMed1980

[New beta-sympatholytic agents. Synthesis and pharmacological activity of isomeric benzthiazole and benzoxazole derivates (author's transl)].

The synthesis and comparative pharmacological studies concerning structure-activity relationship of new benzothiazole, benzisothiazole, benzoxazole, and benisoxazole derivatives with beta-sympatholytic activity are reported. Most of the 4-benzisothiazole derivatives studied strongly act on cardiac beta 1-receptors in rats in situ (2.6-8.3 times propranolol). On the other hand derivatives of 4-benzisoxazole and 5-benzisothiazole are less potent. A strong decrease in activity was observed going from the benzisothiazoles and benzisoxazoles to the isomeric benzthiazoles and benzoxazoles. The active substances also block vascular beta 2-receptors. In the most cases they have little intrinsic adrenergic activity. The observed tendency concerning beta 1-selectivity in rats could not be confirmed in cats. The most potent 4-benzisothiazole derivatives in rats show also - beside some minor differences - very good beta-sympatholytic activity in cats after i.v. as well as after i.d. administration. Similar to the results in rats and cats the 4-(2-hydroxy-3-isopropylamino-propoxy)-1,2-benzisothiazole (LU 24329) was found to possess a high activity in conscious dogs by oral or i.v. application. Both in dogs (i.v.) and in isolated perfused guinea pig hearts LU 24329 is eleven times more active than propranolol in blocking beta 1-receptors. A negative inotropic effect as an expression of non-specific membrane-stabilizing action of LU 24329 is also demonstrated in guinea pig hearts. The effective concentration is 4650 times higher than that effective on beta 1-adrenoceptors. The active compounds have a moderate acute toxicity. The LD50 values in mice after i.p. administration are ranging from 55-174% of the propranolol toxicity.

Adrenergic beta-Antagonists↗
PubMed1980

[Pharmacology of N-(2-imidazolin-2-yl)-N-(4-indanyl)amino (indanazoline), a new vasoconstrictive imidazoline compound].

In animal experiments the new imidazoline derivative N-(2-imidazolin-2-yl)-N-(4-indanyl)amine (indanazoline, E-VA-16, as monohydrochloride active substance of Farial) is characterized by a pronounced vasoconstrictive action after local or intravenous application. This is due to a direct action of the compound on alpha-adrenergic receptors. When applied systemically E-VA-16 being a peripherally acting alpha-sympathomimetic induces a rise in blood pressure and a reduction of heart rate and exerts antiphlogistic, spasmolytic, hyperglycemic and diuretic actions. When given by the intranasal route the substance influences blood pressure and heart rate only at concentrations considerably higher than those intended for use in therapy. After enteral administration the effective doses also markedly exceed the single therapeutic doses. There was no evidence of side-effects restricting the use of the drug as compared to other imidazoline derivatives. Studies on the isolated perfused rabbit ear, however, indicated a broader therapeutic range in local application.

Anesthetics, Local↗
PubMed1979

[Fibrosarcoma in onocytoma (author's transl)].

In a 69-year-old male patient a leftsided renal tumor was found. The patient who initially refused an operation, was treated surgically 3 1/2 years later, when loss of strength and weight as well as pain in the upper abdomen were noted. The tumorweight was 920 g and represented histologically, besides a oncocytic adenoma, a fibrous sarcoma. Both tumors were intermingled. We assume that the malignant growth originated in degenerated areas of the benign adenoma.

Adenoma↗