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Biomedical subjects

K Jaeger

Publications and source records attributed to K Jaeger.

At least 55 records · Page 3Linked to original sources
PubMed1999

Modern alternatives to amalgam: cementable restorations and inlays.

There are still no replacement materials on the market that are equal to amalgam. However, alternatives of differing qualities are available and, for the most part, clinically proven. This article attempts to make a scientific and clinical comparison of these alternatives with respect to esthetics, biocompatibility, chemical durability, and treatment cost. The evaluation suggests that cementable restorations, in particular electroformed inlays and onlays, are superior to bonded ceramic inlays.

Biocompatible Materials↗
PubMed1998

Effect of lung allograft ischaemia duration on postreperfusion graft function and postoperative course.

Lung transplantation is limited by the effects of ischaemia. Previous clinical studies related graft ischaemia duration to post-operative pulmonary function in the ICU, morbidity, and overall survival. This report describes the intraoperative pulmonary allograft function immediately after reperfusion. 23 lung transplantations (15 bilateral, 8 single) were analysed. Donor selection and organ procurement were identical. After pulmonary vasodilation with prostacyclin, allografts were flush-perfused with cold modified Euro-Collins solution. Mean duration of lung ischaemia was 255.1 +/- 35.1 min (190-314 min). Ischaemia times did not differ with respect to the recipient's disease or the use of extracorporeal circulation. After reperfusion, oxygenation indices deteriorated in 73.9% of patients compared with the native lungs (313.4 +/- 163.5 vs 427.2 +/- 96.1, p = 0.006). Linear regression analysis and subgroup analysis both revealed a significant influence of the duration of allograft ischaemia on early transplant function. Ischaemia of more than 4 hours resulted in an acceptable but significantly lower PaO2 (254.9 +/- 143.3 mmHg vs 463.0 +/- 149.2 mmHg, p = 0.011). However, mean time until extubation and time spent in the ICU were not affected. It is concluded that flush-perfusion of the lung with modified Euro-Collins solution provides reliable preservation of lung function up to four hours. Longer ischaemia, up to six hours, is followed by an acceptable but progressively reduced early transplant function.

Adult↗
PubMed1998

Remifentanil, fentanyl, and alfentanil have no influence on the respiratory burst of human neutrophils in vitro.

BACKGROUND: Anaesthetic agents inhibit certain functions of human neutrophils. The respiratory burst (RB) enzyme in the plasma membrane of neutrophils leads to the production of superoxide anion. The oxygen radicals are responsible for killing phagocytised micro-organisms. We investigated the in vitro influence of remifentanil, fentanyl, and alfentanil on the respiratory burst of human neutrophils. METHODS: For the flow-cytometric evaluation, leukocytes were obtained as supernatant following sedimentation and were incubated with the tested drugs. The concentrations in vitro were adjusted to conform to the plasma concentrations reported for anaesthesia and also to 10-fold higher concentrations. The RB was measured by intracellular oxidation of dihydrorhodamine to fluorescent rhodamine after induction of phorbol-myristate-acetate (PMA), Escherichia coli (E. coli) or priming by tumour necrosis factor alpha followed by stimulation of n-formyl-methionyl-leucyl-phenylalanine (TNF-alpha/FMLP). In order to exclude prestimulation of the neutrophil granulocytes, negative controls were carried out. Propidium iodide (PI) was added for viability discrimination immediately prior to flow cytometry measurement. RESULTS: Regardless of the triggering agents chosen (PMA, E. coli, TNF-alpha/FMLP), remifentanil, fentanyl, and alfentanil had no significant effect on the neutrophils' respiratory burst even in concentrations which were higher than those encountered during in vivo conditions. CONCLUSION: With respect to peri- and postoperative risk of infection, anaesthetics and analgetics with no inhibiting effect on neutrophil function should be used. These results show that remifentanil, fentanyl, and alfentanil do not influence the neutrophils' respiratory burst in vitro.

Alfentanil↗
PubMed1997

Intravascular ultrasound-guided percutaneous fenestration of the intimal flap in the dissected aorta.

BACKGROUND: Aortic dissection with branch obstruction is associated with high morbidity and mortality. Fenestration of the dissection flap to relieve distal vessel ischemia is at present largely performed surgically. The surgical mortality and morbidity are high, because most patients are poor candidates for anesthesia or surgery. METHODS AND RESULTS: Nine percutaneous fenestrations (one with additional stenting of the infrarenal true aortic lumen) were performed under local anesthesia in seven patients with aortic dissection. The presenting symptoms were abdominal angina or claudication. By the transfemoral approach, the intimal flap was initially punctured with a needle-catheter combination through which a guidewire was placed across the dissection flap. The fenestration was carried out with a balloon catheter introduced over the guidewire. The procedure was performed under on-line guidance with intravascular ultrasound imaging. The procedure was performed successfully and without complications in all patients. After intervention, symptoms resolved in all seven patients. CONCLUSIONS: Intravascular ultrasound-guided percutaneous fenestration of the intimal flap in symptomatic aortic dissections with distal vessel involvement is a technically feasible and safe procedure that can effectively relieve the patient's symptoms.

Adult↗
PubMed1997

Inhibition of neutrophil respiratory burst and chemotaxis in vitro by thiopentone but not methohexitone.

Administration of high-dose barbiturates may be used as an appropriate adjunctive treatment for control of intracranial pressure. The thiobarbiturate, thiopentone, has been reported to increase the rate of nosocomial pulmonary infection. This may be a substance-related effect of thiobarbiturates and it may be clinically important in barbiturate-sedated patients with severe head injury. Thus, the effects of the dose-response relationship of two commonly used barbiturates (thiopentone and methohexitone) on two vital aspects of neutrophil function were tested. We studied the production of superoxide anion during the respiratory burst by means of a flow cytometric method, and we assessed N-formyl-methionyleucylphenylalanine-induced neutrophil chemotaxis using the results produced by specific migration. The concentrations of thiopentone and methohexitone tested in vitro were adjusted to conform to the plasma concentrations reported for anesthesia and also to 10-fold higher concentrations. Only thiopentone dose dependently decreased respiratory burst and N-formyl-methionyleucylphenylalanine-induced chemotaxis. Methohexitone produced minimal effects in both concentrations. It was demonstrated that thiopentone had a direct effect on the intracellular respiratory burst oxidase enzyme system. The postulated free radical scavenging capacity of thiopentone was ruled out.

Journal Article↗
PubMed1997

Bacteroides fragilis toxin rearranges the actin cytoskeleton of HT29/C1 cells without direct proteolysis of actin or decrease in F-actin content.

Enterotoxigenic strains of B. fragilis associated with childhood diarrhea produce a 20 kD zinc metalloprotease toxin (BFT). BFT is reported to cleave G-actin in vitro and also causes dramatic rounding and rearrangement of the F-actin cytoskeleton in human intestinal epithelial cell lines (HT29) and HT29/C1). To test the hypothesis that the proteolysis of cellular actin by BFT in vivo may contribute to these alterations in morphology and cytoskeletal architecture, we assessed the F-actin content and the arrangement of the F- and G-actin cytoskeleton in BFT-treated HT29/C1 cells by spectrofluorimetry, confocal microscopy, and immunoblotting. BFT-treated cells were compared to cells treated with C. difficile toxin A (CDA) or cytochalasin D. Using spectrofluorimetric quantification, the F-actin content of BFT- and cytochalasin D-treated cells was unchanged in contrast to a significant decrease in CDA-treated cells. By confocal microscopy, the arrangement of F- and G-actin in all treated cells was markedly different than control cells. There was no change in the immunoblotting pattern of actin in the Triton-soluble or -insoluble cellular fractions of BFT-treated HT29/C1 cells. We conclude that BFT alters the F- and G-actin cytoskeletal architecture of HT29/C1 cells without direct proteolysis of actin or decrease in F-actin content.

Actins↗
PubMed1997

[Effect of remifentanil on respiratory burst of human neutrophilic granulocytes in vitro].

Recovery chances for severely ill patients have been significantly improved by the progress of intensive care medicine. The success of any therapy, however, is still jeopardized by postoperative infections and septic complications. In the early stage of bacterial infections polymorphonuclear leukocytes (PMNL) play a decisive role. After PMNL activation, the production of oxygen radicals during the respiratory burst (RB) denature the phagocytosed micro-organisms. Remifentanil is a new opioid which has been safely administered to various patient groups and shows pharmacokinetic advantages in comparison to the already established opioids. As some intravenous anaesthetics can influence PMNL functions, we analysed, by flow cytometry, the in vitro influence of clinically relevant remifentanil concentrations on the respiratory burst. In our study remifentanil had no influence on the respiratory burst of human PMNL in vitro, regardless of the RB triggering agents chosen.

Analgesics, Opioid↗
PubMed1996

Association of allelic losses on human chromosomal arms 11Q and 16Q in sporadic breast cancer.

Breast-carcinoma development presumably results from multiple mutational events in tumor-associated genes. Certain results indicate that some tumor-suppressor genes may combine their pathogenetic potential to synergistically promote tumor growth. In an effort to identify such mechanisms in breast tumors, a series of 77 (group I) paired blood tumor samples from patients with sporadic mammary carcinomas was analyzed for loss of heterozygosity with 15 polymorphic markers on the chromosomal arms 7q, 11q, 13q, 16q, 17p and 17q. A significant association was observed for the combination of allelic losses on chromosomes 11q and 16q. In order to confirm these findings, we studied a second independent series of 189 breast-tumor patients (group 2) with comparable histopathological tumor stages. Group 2 was examined for the same genetic alterations using the identical set of polymorphic markers. The data from this group confirmed the detected association of loss of heterozygosity on chromosomes 11q and 16q and indicate the cooperation of putative tumor-suppressor genes on the chromosomal arms 11q and 16q in a sub-set of breast carcinomas. The regions involved harbor the candidate genes ATM (mutated in ataxiatelangiectasia) on chromosome 11q23 and UVO (uvomorulin, cadherin E) and BBCI (breast basic conserved I) on chromosome 16q22-q24.

Alleles↗
PubMed1996

Fate and biological effects of polymeric MDI (4,4'-diphenylmethane diisocyanate and homologs) in small artificial ponds.

The effects from a simulated accidental pollution event in a pond with polymeric MDI (4,4'-diphenylmethane diisocyanate and homologs) on different trophic levels of the aquatic ecosystem were investigated in small artificial ponds. Three 4.5-m3 volume ponds, interconnected with closable locks, were provided with natural lake sediment and ground water. Caged fish (rainbow trout, Oncorhynchus mykiss) were added to each pond, and the interconnecting locks were kept open to establish nearly identical physicochemical and biological conditions. At this stage, the ponds were isolated from one another and MDI was added at a dosage of 1 g/liter on top of the sediment of treated part of the first pond, 10 g/liter to the second pond, and 0 g/liter to the third pond (untreated control). Neither the applied monomer MDI nor its potential reaction product MDA (4,4'-diphenylmethanediamine) was detected in water or accumulated by fish. The MDI polymerized to inert polyurea on the sediment of the test ponds. This polymerization formed carbon dioxide, released as bubbles which floated to the water surface. Some carbon dioxide was solubilized in water and reduced the water pH of about 9 by 2.0 units as an average in the high-dosed pond and 0.7 in the low-dosed pond. This reduction caused some other minor changes in the physicochemical characteristics of the pond water. Neither application rate caused any direct effect on the pelagic community (phytoplankton, zooplankton, fish, macrophytes) of the test ponds. Some minor indirect effects caused by the production of carbon dioxide were observed in phyto- and zooplankton community structures. Also, an increase of macrophyte growth was noted. Organisms living in the untreated part of the sediment (macrobenthos) were affected as a result of physical obstructions in this habitat. These populations, however, regained densities equivalent to the control after some weeks, except for Bivalvia which have too long of a generation time for the test period of this study.

Allergens↗
PubMed1996

Flow cytometry evaluation of the in vitro influence of four i.v. anaesthetics on respiratory burst of neutrophils.

Exposure of neutrophils to anaesthetic agents may alter their functional characteristics and in patients undergoing long-term sedation this may be clinically relevant. We have investigated the in vitro influence of propofol, thiopentone, methohexitone and midazolam on phorbol 12-myristate 13-acetate (PMA)-induced respiratory burst of neutrophils by the intracellular oxidative transformation of dihydrorhodamine-123 to the fluorescent dye rhodamine-123 via flow cytometry. We tested in vitro concentrations similar to sedating, anaesthetic, 10-fold sedating and 10-fold anaesthetic plasma concentrations. All drugs showed similar inhibition of respiratory burst at sedating concentrations (1-6%). At anaesthetic concentrations, propofol produced significantly higher mean inhibition (7.3%) compared with thiopentone (4.5%) and methohexitone (0.9%). At 10-fold anaesthetic concentrations inhibition of respiratory burst by propofol was almost complete (90.8%) and significantly higher than that by thiopentone (29.2%) and methohexitone (1.8%). Methohexitone and midazolam had only minimal effects at all concentrations. The effect of the solvent of propofol (10% Intralipid) was similar to that of propofol. Thus suppression of respiratory burst of neutrophils by propofol may be caused by this lipid carrier.

Anesthetics, Intravenous↗
PubMed1994

[Simultaneous surgical and technical catheter revascularization of the lower extremity].

Intraoperative balloon angioplasty was performed on 17 patients and 19 arteries undergoing a concomitant vascular reconstructive procedure during the past 24 months. All angioplasties were performed with the aid of digital substraction angiography (DSA) in the operating room. The primary purpose of intraoperative angioplasty was mainly to increase outflow (18) or inflow (1) in conjunction with a planned vascular procedure. Dilatation obviated the need of more extensive vascular reconstruction in these elderly patients.

Aged↗
PubMed1993

Predictive diagnosis in familial adenomatous polyposis: evaluation of molecular genetic and ophthalmologic methods.

Familial adenomatous polyposis (FAP) is an autosomal-dominant precancerous condition characterized by the appearance of hundreds to thousands of colorectal polyps. The responsible gene (APC) has been mapped and identified. The cancer prevention policy for persons at risk (children and sibs of FAP patients) implies an early diagnosis of the disease. A presymptomatic diagnosis allows to limit the regular rectosigmoidoscopic examination to those persons having inherited the disease gene. Presymptomatic diagnosis can be achieved by molecular genetic methods (direct and indirect genotype analysis) and by funduscopic examination of retinal pigment anomalies that are characteristic for FAP. The aim of this study was to examine the power of the molecular genetic and ophthalmologic methods for presymptomatic diagnosis in FAP. For this purpose 60 FAP families with 171 persons at risk were examined. By direct mutation analysis a presymptomatic diagnosis was achieved in 32% of the persons at risk; indirect genotype analysis was possible in 88% of the families in which more than one FAP patient was available. The ophthalmologic examination allowed a presymptomatic conclusion in 79% of the persons at risk. In no case there was a discrepancy in the results between the methods applied. The ophthalmologic presymptomatic test is useful especially in families where the index patients has a new mutation in the APC gene that has not been identified.

Adenomatous Polyposis Coli↗
PubMed1992

[Histomorphologic findings in human expanded tissue].

Forty biopsies from 22 patients undergoing tissue expansion were examined histologically. Expanded skin demonstrated a generally unconspicious morphology of the epidermis, dermis and subcutis. Adnexal organs of the skin were preserved. Mean epidermal thickness was increased to 710 +/- 240 microns compared to 624 +/- 215 microns in the controls. The tissue expanders were bordered by a richly vascularized connective tissue capsule with a very variable mean thickness of 795 +/- 712 microns. These histologic findings in human tissues support experimental evidence for a real increase in tissue by expansion.

Adolescent↗
PubMed1991

Regulation of postprandial mesenteric blood flow in humans: evidence for a cholinergic nervous reflex.

Duplex ultrasound was used to investigate superior mesenteric artery haemodynamics in humans in order to determine the physiological importance of postprandial blood concentrations of cholecystokinin octapeptide (CCK8), gastrin 17, secretin, and glucagon and to study whether a nervous cholinergic reflex mechanism has a role in the postprandial mesenteric blood flow response. Duplex parameters of vessel diameter, mean velocity, and flow volume were determined serially in the basal state and after stimulation. Changes were compared with baseline values. Superior mesenteric artery parameters were significantly increased over baseline values after a liquid test meal, but ingestion of saline did not cause any changes. Hormones infused simultaneously at postprandial concentrations did not change mesenteric blood flow. When they were infused at pharmacological doses, however, a significant increase in flow parameters was observed. Pretreatment with atropine significantly (p less than 0.05) reduced the mesenteric blood flow response to meal stimulation (57%). These data suggest that the four hormones tested are not of quantitative importance in regulating postprandial superior mesenteric artery blood flow. A cholinergic nervous reflex, however, participates in the control of food induced mesenteric artery flow changes.

Adult↗
PubMed1991

[Characteristic contributions of the venous duplex exam].

The major advantage of non invasive duplex scanning is the ability to combine its imaging capability (information on the morphology) with the possibility to detect Doppler spectra (hemodynamic information) of the visualised segment. This new method, mainly used for the investigation of arterial diseases, is more and more applied in phlebology too. The technique is very reliable in the diagnosis of deep vein thrombosis and in the investigation of varicose veins and their junctions with the deep venous system. In these indications duplex scanning is likely to become a standard technique. The use of duplex in phlebology, however, should not be limited to these indications. In this paper the results of some special phlebologic duplex studies are presented: A) changes in the subclavian vein induced by pace maker electrodes; B) utility in the differential diagnosis of deep vein thrombosis; C) efficacy in the control of caval filter; D) measurements of physiologic venous hemodynamics and quantification of phlebologic drug effects.

Humans↗