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Biomedical subjects

E Fink

Publications and source records attributed to E Fink.

At least 91 records · Page 5Linked to original sources
PubMed1986

Chemical synthesis and expression of a gene coding for hirudin, the thrombin-specific inhibitor from the leech Hirudo medicinalis.

A DNA containing the coding sequence for the proteinase inhibitor protein hirudin from the leech Hirudo medicinalis has been obtained by enzymic ligation of chemically synthesized deoxyoligonucleotides. The 226 bp synthetic gene carries signals for the translation initiation and termination. Fragment synthesis was performed by the Khorana ligation method as well as by the fill-in method. Efficiencies of these two methods are compared. The synthetic gene was expressed in E. coli as a fusion protein with beta-galactosidase under the control of the lac-promoter as well as a non-hybrid protein under the control of the lambda PL-promoter. The non-hybrid expression product was shown to have similar biological properties as the authentic protein isolated from the leech.

Amino Acid Sequence↗
PubMed1986

Angiotensin converting enzyme inhibitors in diabetes: experimental and human experience.

Peripheral glucose metabolism was studied during the influence of elevated systemic kinin levels by either application of exogenous bradykinin (BK) or inhibition of endogenous kinin degradation by angiotensin converting enzyme inhibitors (ACEI). In infusion experiments in streptozotocin-diabetic rats, both BK (0.3 micrograms/min) and ACEI (300 micrograms captopril/100 g) showed a significant reduction of elevated blood glucose levels. In man, non-insulin dependent diabetics (NIDD) and healthy subjects in postoperative (POP) stress were examined. Peripheral insulin-sensitivity and muscular glucose balance were determined using the glucose clamp technique and the forearm technique. In NIDD as well as in POP subjects, impaired peripheral insulin responsiveness, as evaluated by whole body glucose consumption, was improved up to 50% by application of BK (80 micrograms/h i.v.) or ACEI (25 mg captopril p.o.), respectively. This was most probably due to accelerated muscular glucose uptake which was assessed in the same experiment and found to be increased 2- to 3-fold under these conditions. As a molecular basis for the observed effects on muscular glucose uptake, phosphofructokinase was found to be markedly stimulated by BK (8 X 10(-10)mol/l) in the isolated perfused rat heart, suggesting accelerated glycolytic flux. It may be concluded that ACEI increase muscular insulin responsiveness, thus being beneficial in insulin-resistant states as well as in hypertension. This metabolic effect is most probably due to elevated systemic kinin levels. Further investigations are required to evaluate the clinical relevance of these findings.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1985

Trypanosoma brucei: five commonly used trypanocides assayed in vitro with a mammalian feeder layer system for cultivation of bloodstream forms.

The in vitro activity of five commonly used trypanocides on bloodstream forms of Trypanosoma brucei brucei TC 221 was examined in 24-well culture plates in the presence of bovine fibroblast feeder layer cells. The minimum effective concentrations determined were as follows: Berenil 1.0 microgram/ml; Samorin 10.0 micrograms/ml; Antrycide dimethylsulfate 0.1 microgram/ml; Arsobal 0.01 microgram/ml; Naganol 1.0 microgram/ml. Contrary to values obtained with other in vitro assays, minimum effective concentrations obtained here were within the range of drug levels reached in blood, plasma, or serum of humans and animals after treatment with curative doses. The trypanocidal activity of Naganol in this assay was of particular interest, since Naganol has been hitherto considered to be inactive in vitro.

Animals↗
PubMed1985

Tissue kallikrein of human seminal plasma is secreted by the prostate gland.

Samples of human seminal plasma were subjected to gel filtration, and the eluted fractions were analysed for their contents of tissue kallikrein-like antigen, arginine esterase activity and kininogenase activity. Two peaks of tissue kallikrein-like antigen were detected with apparent molecular masses of about 72 and 48 kDa. As judged by the criteria of molecular mass, immunoreactivity, kininogenase activity, identification of the released kinin as kallidin and inhibition studies, a genuine tissue kallikrein has been identified in the 48-kDa peak. In addition, this peak contains one or more species of immunoreactive tissue kallikrein which differ in molecular mass and enzymatic activities. The 72-kDa peak probably represents the complex of tissue kallikrein with alpha 1-proteinase inhibitor rather than a true high molecular mass tissue kallikrein. The prostate gland was identified as the site of origin of the tissue kallikrein in the seminal fluid by indirect methods and by demonstrating immunoreactive tissue kallikrein in prostatic tissue and secretion.

Chromatography, Gel↗
PubMed1985

In vitro activity of the trypanocidal diamidine DAPI on animal-infective Trypanosoma brucei brucei.

A mammalian feeder layer system for the continuous cultivation of infective bloodstream forms of Trypanosoma brucei brucei has been used for investigating the antitrypanosomal activity of the aromatic diamidine DAPI. The drug was active at concentrations which can be reached under physiological conditions. The minimum effective concentration was 0.05 micrograms/ml. Minimum exposure times required for antitrypanosomal activity were dependent on the drug concentrations. Furthermore, DAPI was found to cause toxic side effects on bovine fibroblast feeder layer cells at high drug concentrations (10 micrograms/ml), however, at low concentrations (1 microgram/ml), the drug acted selectively on trypanosomes. Both the reproducibility and the high sensitivity to drugs of the system make this assay a valuable technique for chemotherapeutic studies on trypanosomes.

Animals↗
PubMed1983

[Bioavailability of glycerol trinitrate (nitroglycerin) from an ointment preparation].

After application of an ointment of glycerol trinitrate (nitroglycerin, Nitrofortin; in the following briefly called GTN) the bioavailability of the unchanged GTN was evaluated. For that purpose a gas chromatographic/mass spectrometric method was employed, the only method which guarantees the selectivity and sensitivity necessary for this kind of studies. In this respect selectivity means that only the unchanged drug is determined and degradation and/or biotransformation products are measured only if needed. Considering the well-known tremendous inter-individual variations, which are quite common in studies with this compound, and the associated problems of getting statistically relevant data the study was performed on 12 volunteers. Detectable GTN-levels were obtained up to 48 h after application, maximum plasma levels (836.1 +/- 124.2 pg/ml) were reached after 1.37 +/- 1.55 h. 12 h after application plasma concentrations of 154 +/- 20 pg/ml were observed which decreased to 65 +/- 13 pg/ml after 24 h.

Adult↗
PubMed1982

Qualitative measurement of cerebral infarction using ultraviolet fluorescence.

A reliable method of macroscopically determining the volume of cerebral infarction using ultraviolet fluorescence was developed in an animal model. Cerebral infarction was induced in 40 dogs by occluding the distal internal carotid and middle cerebral arteries. No barbiturates were administered. Intravenous sodium fluorescein was given before the animal was killed. Following fixation, 1 cm coronal sections were evaluated with ultraviolet light of 366 nm wavelength. The area of induced fluorescence for each section was determined using a grid overlay. Microscopic examination revealed that the areas of ischemic cell necrosis corresponded to areas of maximal fluorescence. This is an easily reproducible method to determine the volume of cerebral infarction.

Animals↗
PubMed1982

Studies on the excretion of tissue kallikrein from blood into the urine.

Enzymatically active or diisopropyl fluorophosphate-inactivated pig pancreatic kallikrein were infused intravenously into dogs. Pig pancreatic kallikrein in plasma and urine was measured by a radioimmunoassay. The total excreted pig pancreatic kallikrein was 0.8-3.1% of the administered dose when active kallikrein was infused and 21.6% when inactive kallikrein was infused. The renal clearance of the administered kallikrein was found to be between 0.9 and 4.1 ml/min, which corresponds to 2.4-6.4% of the inulin or creatinine clearance. These results indicate that renal synthesis of tissue kallikrein and its direct secretion into the urine is not the exclusive mechanism of the excretion of tissue kallikrein into the urine. A second mechanism, the renal transfer of endogenous tissue kallikrein from the blood into the urine, can also contribute to the total amount of excreted urinary kallikrein.

Animals↗
PubMed1982

Comparison of immunological and enzymatic properties of human urinary and pancreatic kallikrein.

Human urinary and human pancreatic kallikreins were compared by radioimmunoassay, immunoelectrophoresis, by their enzymatic activity using the substrate Ac-Phe-Arg-OEt and by their biological activity employing the dog blood pressure assay. The only significant difference observed was a higher anodal mobility of the urinary kallikrein under the conditions of immunoelectrophoresis.

Animals↗
PubMed1982

Pentobarbital changes compartmental contribution to cerebral blood flow.

Barbiturates were administered to normal dogs, establishing an isoelectric electrocorticogram. Cortical cerebral blood flows (CBF) and deeper CBF's were respectively measured by krypton-85 (85Kr) and xenon-133 (133 Xe). Following barbiturate administration, the two methods of measuring CBF showed a poor coefficient of variation (r=0.12, p less than 0.05). The cortical flows decreased less than the fast compartment flows. A shifting of percentage contribution of flow to the slow compartment (60% increase, p less than 0.001) was observed after barbiturate infusion. A selective shunting of blood flow to the slower areas may explain the lowering of intracranial pressure and protection of the deep white matter observed by many authors who use barbiturates in clinical an experimental situations.

Animals↗