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Biomedical subjects

I Herrmann

Publications and source records attributed to I Herrmann.

At least 19 recordsLinked to original sources
PubMed1997

Adenosine kinase inhibitor GP515 attenuates hepatic leukocyte adhesion after hemorrhagic hypotension.

Adhesion of leukocytes to the vascular endothelium hallmarks a key event in neutrophil-mediated organ injury after ischemia-reperfusion. The autacoid adenosine has been shown to inhibit activated neutrophil function and to interfere with leukocyte-endothelial adherence. Its therapeutic use in ischemia-reperfusion, however, has been limited by severe cardiovascular side effects. We therefore investigated the effects of the adenosine kinase inhibitor GP515 in vivo on hepatic leukocyte-endothelial interactions in a rat model of hemorrhagic hypotension and resuscitation, using intravital microscopy. Rats were pretreated with either GP515 (0.25 mg/kg) or saline in a randomized and blinded manner and subjected to pressure-controlled hemorrhagic hypotension at a mean arterial pressure of 40 mmHg for 60 min followed by 5 h of resuscitation. Five hours after resuscitation in saline-treated animals, firm leukocyte-sinusoidal adhesion was strongly enhanced in the periportal and midzonal sublobular regions, and sinusoidal diameters were also markedly reduced. Compared with saline treatment, GP515 significantly attenuated shock and resuscitation-induced leukocyte adhesion in both sublobular regions. Moreover, although GP515 did not significantly affect macrohemodynamical and hematological parameters, it enlarged narrowed sinusoidal diameters and tended to improve sinusoidal blood flow. We propose that the adenosine-regulating agent GP515 has a therapeutic potential to attenuate ischemia-reperfusion-induced inflammation by capitalizing on the beneficial anti-inflammatory effects of endogenous adenosine.

Adenosine Kinase↗
PubMed1993

Periodontal indices around natural and titanium abutments: a longitudinal multicenter study.

This multicenter prospective study on the use of an implant system involved 9 centers and reports on the periodontal aspects after 3 years of observation. A total of 558 implants in 159 patients with 197 bridges all independent from natural teeth were originally included. Because of failures and patient withdrawals the number of implants was reduced to 460 and bridges to 174. The cumulative success rate for implants, starting from implant placement, is 94.3% after 2 years and 93.9% after 3 years indicating a leveling of implant loss. Failures concentrated in patients with a high plaque index. The loss of marginal bone was during the second and third years only 0.03 mm per year as an average while it was 0.4 mm during the first year. There were no reports of intense gingival inflammation in any of the patients and the plaque and gingivitis index behaved similarly around abutments and teeth. The probing pocket depth was significantly reduced over the observation time. The resistance towards marginal bone loss around these implants confirms the previous studies on fully edentulous patients.

Adolescent↗
PubMed1993

The wide fixture: a solution for special bone situations and a rescue for the compromised implant. Part 1.

This paper describes a new 5.0-mm-diameter self-tapping implant, a modification of the standard Brånemark fixture designed to increase the amount of bone-to-titanium surface contact and to capture dense bone at the lateral and crestal borders of the alveolus. Indications for its use include (1) areas of inadequate bone height, (2) areas of poor bone quality (type IV), and (3) immediate replacement of non-integrated or fractured implants. This preliminary report discusses the design alterations and surgical techniques available to treat these difficult bone situations.

Alveolar Bone Loss↗
PubMed1992

In vitro effect of vanadate on content, secretion and biosynthesis of insulin in isolated islets of normal Wistar rats.

In in vitro experiments the effect of (Na-ortho)vanadate (1-50 mumol/l) on content, secretion and biosynthesis of insulin was investigated in isolated islets of normal Wistar rats. Compared with controls insulin content is unchanged, but insulin secretion and biosynthesis rate are significantly reduced; secretion is significantly more reduced in the basal than in the stimulating glucose medium. Our results support the view that vanadate exhibits its influence on insulin metabolism in the beta cell already.

Animals↗
PubMed1992

Cardiodynamic changes during passive tilt and acute nitrate therapy.

In six patients with normal left ventricles and seven post-myocardial infarction patients cardiodynamic changes during tilt and acute nitrate medication were investigated. The conductance catheter was used for on-line registration of left ventricular volumes and a microtip manometer for high-fidelity pressure recordings. We analysed left ventricular end-diastolic volume index (EDVI) ejection fraction (EF), cardiac index (CI), heart rate (HR), end-systolic pressure (ESP) and end-diastolic pressure (EDP) in the supine position and 30 s after passive upright tilt. Supine and standing measurements were performed without medication and 2 min after acute nitrate medication (0.8 mg sublingual nitroglycerin). After unloading by upright tilt there was a similar reduction of average EDVI in the control group (-18 +/- 7 ml.m2) and in the post-infarction group (-21 +/- 18 ml.m2). The effect of nitroglycerin on EDVI (-12 +/- 4 ml.m2 control, -7 +/- 6 ml.m2 post-infarction) was less than the effect of upright tilt. EF in the control group improved by +8 +/- 5% (in absolute values) during passive tilt; the combined effect of tilt and nitrate was +12 +/- 6% EF (p < 0.05). In the post-infarction group EF did not change significantly during tilt and/or nitrate therapy. In the patients with normal regional ventricular function, CI during tilt was maintained at a constant level. In the post-infarction group the reduction in CI was not significant. Although the reduction in EDVI was similar in the control and infarction groups, the infarction group did not respond to the cardiodynamic change by increasing EF.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Sublingual↗
PubMed1992

A multicenter study of overdentures supported by Brånemark implants.

Nine clinical centers participated in a prospective study of overdentures supported by Brånemark implants in the maxilla or mandible. The study initially comprised 133 patients provided with 117 implants placed in the maxilla and 393 implants placed in the mandible. The preliminary results indicate a success rate in the mandible comparable with the reports on fixed prostheses. Conversely, overdenture treatment in the maxilla seems to be less favorable than previous reports of fixed restorations. The differences between the fixed and the present overdentures in the maxilla were mainly based on differences in patient selection and bone quality. A total of 32 implants was mobile and removed and another 29 implants were lost to follow-up because of patient dropout up to the first annual checkup after denture placement. A higher implant failure rate occurred in the maxilla. Mucosal reactions were also more unfavorable around implants placed in the maxilla.

Adult↗
PubMed1991

Osseointegrated implants for single tooth replacement: a 1-year report from a multicenter prospective study.

One hundred seven dental implants were inserted to support single tooth restorations in 92 patients participating in a prospective multicenter investigation. Only three implants (2.8%) were lost after 1 year of clinical function. Most of the remaining restorations were esthetically successful by using modified components. The gingival condition was healthy around the single crowns and coincided well with the clinical situation around the permanent teeth. The most obvious problem experienced during the first year was related to loose abutment screws. Twenty-six percent of the screws retaining crowns were retightened during the observation period, but the frequency of loose screws had a tendency to decrease as the study progressed.

Adult↗
PubMed1990

Applicability of osseointegrated oral implants in the rehabilitation of partial edentulism: a prospective multicenter study on 558 fixtures.

Nine clinical centers using the Brånemark System participated in a prospective study of 159 partially edentulous patients between 18 and 70 years of age. Clinical parameters evaluated were plaque index, gingivitis, pocket depth, bleeding index, tooth mobility, and stomatognathic function. Initially, 558 fixtures were placed and 521 remained in the study following prosthesis placement (199 prostheses in 154 patients). Fixtures were lost or unaccounted for because of nonintegration prior to prosthesis fabrication (19), patient withdrawal (11), prosthodontic reasons (6), and failure during prosthetic procedures (1). Failure was primarily attributable to unfavorable bone quality, sex (more in males), and smaller fixture size. Complications and failure related to other patient characteristics are presented. After 1 year of a 5-year study, preliminary results suggest that a success rate equal to or better than that obtained with edentulous patients may be expected.

Adult↗
PubMed1990

[How to interpret success rates in implantology].

How can almost every oral implant manufacturer claim success rate of nearly 100%, when clinicians are still in the process to include implants in their practice. Articles on long-term data are still scarce in the international Journals today. Often the different safety and effectiveness of various implant systems are based on the data that Professor Brånemark started to collect 25 years ago. To interpret an article demands knowledge about study design, statistical analyses as well as type of diagram. There are number of important aspects to consider when reading a report on success rates. To understand why some studies can show almost 100% success rates for the upper jaws and others 80%, one must be aware of the important parameters which affect the results. In order to compare the results of one study with the results of another, these parameters, and how they are applied must be taken into consideration.

Data Interpretation, Statistical↗
PubMed1989

Streptozotocin diabetes in spontaneously hypertensive rats.

The aim of our experiments was to find out to what extent male spontaneously hypertensive (SH) as well as normotensive Wistar-Kyoto (WKY) and Wistar-Schönerlinde (WS) rats developed changes of the endocrine pancreas function in response to streptozotocin (SR). 4 week old WS, WKY and SH rats were given ip. injections of 70 or 100 mg SR/kg and were killed at an age of 8 weeks, after which blood glucose, and in isolated islets, insulin-leakage, insulin secretion and insulin biosynthesis were determined; histologically the relative volume density of islet tissue was estimated. The results demonstrated that the intensity of the SR-caused damage to the endocrine pancreas differs considerably in the three strains of rats. The damage increases in the order WS, WKY, SH rats. These findings are indicative of the role played by genetic predisposition and of an increase in damage to the endocrine pancreas due to hypertension.

Animals↗
PubMed1988

The thermodynamic essence of the reversible inactivation of Na+/K+-transporting ATPase by various digitalis derivatives is relaxation of enzyme conformational energy.

This paper reports on the kinetic and thermodynamic parameters describing the interaction of selected digitalis derivatives with hog and guinea-pig cardiac (Na+ + K+)-ATPase (Na+/K+-transporting ATPase EC 3.6.1.37). 32 digitalis derivatives were characterized as to the values of the delta G0', delta G----not equal to, and delta G----not equal to quantities in their interaction with (Na+ + K+)-ATPase from hog cardiac muscle in the presence of ATP, Mg2+, Na+ and K+. Nine derivatives were additionally characterized as to the values of the delta H0', delta S0', delta H----not equal to, delta S----not equal to, delta H not equal to, and delta S not equal to quantities in their interaction with the hog enzyme promoted by ATP, Mg2+ and Na+ in the presence or absence of K+. The formation of the inhibitory complexes is in any case an endothermic, entropically driven process. The Gibbs energy barriers in the formation and dissociation of the complexes, delta G----not equal to and delta G----not equal to, are imposed by large, unfavourable delta H not equal to values. K+ decreases the delta G0' value by increasing the delta G----not equal to value more than the delta G----not equal to value. In comparison with hog (Na+ + K+)-ATPase, the interaction of three derivatives with guinea-pig cardiac enzyme in the presence of ATP, Mg2+, Na+ and K+ is characterized by lower delta G0' values caused by lower favourable delta S0' values, and is accompanied by lower delta G----not equal to values. The magnitude of the kinetic parameters and the characteristic of the thermodynamic quantities describing the interaction between various digitalis derivatives and (Na+ + K+)-ATPase, indicate the induction of substantial conformational changes in the enzyme protein. A large entropy gain in the enzyme protein, observed irrespective of enzyme origin and ligation, appears to be the common denominator of the inhibitory action of all digitalis derivatives studied, suggesting that the digitalis-elicited relaxation of high conformational energy (negentropy strain) of the enzyme protein is the thermodynamic essence of the reversible inactivation of (Na+ + K+)-ATPase.

Adenosine Triphosphate↗
PubMed1988

Diabetogenic effects of N-nitrosomethylurea in rats.

The influence of a single i.v. injection of 75 or 175 mg N-nitrosomethylurea (NMU)/kg into Wistar rats on plasma glucose, i.p. glucose tolerance, plasma insulin and glucagon, glucose stimulated insulin secretion and release as well as on the biosynthesis of insulin in isolated pancreatic islets have been investigated at set intervals between the 3rd day and the 6th week post injectionem. At the end of the experimental period all NMU-treated animals were alive but had significantly reduced body mass. All animals remained normoglycemic even after the glucose load. 3 days after drug application plasma insulin decreased only insignificantly in the 175 mg NMU-group, whereas plasma glucagon was significantly reduced in both drug-groups; after 3 and 6 weeks the reduction of plasma glucagon was still about 30 percent. In isolated islets the glucose stimulated insulin secretion, the percent stimulation of insulin release and insulin biosynthesis were significantly decreased.

Animals↗
PubMed1986

Characterization of membrane-associated growth inhibitor activity for Ehrlich ascites mammary carcinoma cells.

Purified plasma membranes obtained from bovine milk or from bovine mammary gland inhibited in vitro growth of Ehrlich ascites mammary carcinoma cells. Plasma membranes derived from tumor cells or from tumor tissue were inactive. Growth inhibition by milk fat globule membranes was shown to be due to release of membrane-associated inhibitory factors into the medium. Gentle removal of proteins from the surface of milk fat globule membranes succeeded in recovery of a fraction inhibiting cell growth specifically. The same fraction contained the antigen cross-reacting with an antiserum raised against the previously purified 13 kD growth inhibitor from bovine mammary gland.

Animals↗
PubMed1984

Interaction of cardiac glycosides and Na,K-ATPase is regulated by effector-controlled equilibrium between two limit enzyme conformers.

The paper describes the dissociation parameters of the complexes between [3H]-digitoxin and Na,K-ATPase (Na+ + K+-activated, Mg2+-dependent ATP phosphohydrolase, E.C. 3.6.1.3) from pig cardiac muscle and brain cortex formed and dissociated in the presence of different combinations and concentrations of the enzyme effectors ATP, Mg2+, Na+ and K+. Systematic variation of effector-ligation of Na,K-ATPase allowed production of glycoside complexes with two enzyme conformers only, which showed either rapid or slow dissociation kinetics. Appropriate changes of enzyme ligation allowed the interconversion of the two conformer types. Biphasic, rapid and slow glycoside release was not bound with the presence of two Na,K-ATPase isozymes, but caused by the enzyme ligation-determined coexistence of the two conformers of Na,K-ATPase. The rate constants for the rapid and slow glycoside release were within the complexes of each dissociation type much alike indicating uniform isomerization kinetics of the two conformers even when differently liganded. Taken together, the observations indicated the effector-controlled isomerizations of two conformers of Na,K-ATPase possessing different geometries of the glycoside binding domain. Present findings and relevant literature data were integrated in a circular, consecutive and simultaneous model for induced conformation changes that accounted for the regulation of the interaction of cardiac glycosides and Na,K-ATPase through an effector-controlled equilibrium between two limit enzyme conformers.

Adenosine Triphosphate↗
PubMed1984

[Changes in the cholinesterase activity and glucose concentration in the blood induced by paraoxon in rabbits immunized against paraoxon].

The immunization of rabbits with a paraoxon-HSA-conjugate resulted in an antibody response with titres of 1:25000 to 1:100000 of antisera dilution and average affinity constants K0 of 10(6) M-1 and heterogeneity indices of 0.8 to 0.9 calculated by means of the Sips equation. The serum cholinesterases and the erythrocyte acetylcholinesterase in immunized rabbits were protected against a stronger inhibition by parenteral application of paraoxon. An increase of blood glucose after paraoxon application to immunized rabbits could not be observed but was detectable in unimmunized animals.

Acetylcholinesterase↗
PubMed1982

Inotropic, chronotropic and dromotropic effects of prenalterol, a new cardiostimulant drug.

Prenalterol (H 133/22) is an adrenergic beta-receptor stimulator which unlike isoproterenol is both orally active and has a long duration of action. The inotropic, chronotropic and dromotropic effects of prenalterol were investigated in pentobarbital anaesthetized dogs. Prenalterol was found to increase left ventricular maximum dP/dt in a dose-dependent manner up to a dose level of 50 micrograms/kg. Additional doses resulted in only small further increases in cardiac contractility. Electrophysiological studies were done to compare the effects of prenalterol and isoproterenol on sinus node and ventricular pacemaker function. Complete AV block was produced by electrocauterization of the His bundle. Prenalterol accelerated both ventricular and sinus node pacemakers at doses up to 50 micrograms/kg. The increase in ventricular rate was greater than the increase in sinus rate following supramaximal inotropic doses of prenalterol yet no ventricular extrasystoles were ever observed. Similar acceleration of the ventricular and sinus node pacemakers were observed by infusion of isoproterenol. Prenalterol and isoproterenol accelerated AV nodal conduction and ventricular conduction but had little effect upon His-Purkinje conduction. Sinus node reset time was abbreviated as was the functional and effective refractory periods of the atrium and AV nodes.

Animals↗
PubMed1982

[Isolation of an alpha-globulin from rabbit serum responsible for a cobalt(II) ion-induced change in conformation of fibrinogen].

A change in conformation of fibrinogen, caused by cobaltous ions after parenteral application or incubation of plasma, is dependent on the presence of species specific plasma proteins. These proteins, which can be found only in some animals, have not yet been identified. An glycoprotein, responsible for the cobalt effect, was isolated from rabbit serum. It migrates immunoelectrophoretically as an alpha-globulin. In the SDS electrophoresis it was shown to migrate in front of albumin. The actions of this protein, induced by cobaltous ions, could be inhibited by complexing and SH groups alkylating compounds.

Alpha-Globulins↗