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Biomedical subjects

B Peter

Publications and source records attributed to B Peter.

At least 19 recordsLinked to original sources
PubMed2005

The effect of bisphosphonates and titanium particles on osteoblasts: an in vitro study.

In an attempt to increase the life of cementless prostheses, an hydroxyapatite-coated implant which releases a bisphosphonate has been suggested as a drug-delivery system. Our in vitro study was designed to determine the maximum dose to which osteoblasts could be safely exposed. Our findings demonstrated that zoledronate did not impair the proliferation of human osteoblasts when used at concentrations below 1 microm. Murine cells can be exposed to concentrations as high as 10 microm.A concentration of 0.01% of titanium particles did not impair the proliferation of either cell line. Zoledronate affected the alkaline phosphatase activity of murine osteoblasts through a chelation phenomenon. The presence of titanium particles strongly decreased the alkaline phosphatase activity of murine osteoblasts. We did not detect any synergic effect of zoledronate and titanium particles on the behaviour of both human and murine osteoblasts.

Alkaline Phosphatase↗
PubMed2004

Calcium phosphate drug delivery system: influence of local zoledronate release on bone implant osteointegration.

Despite total hip replacement (THR) gives generally satisfactory results, the quality of outcome in young patients is markedly decreased compared to the average THR outcome. For this population, pharmacological treatment with bisphosphonate would be beneficial to decrease the peri-implant osteolysis. However, as this population does not necessarily suffer from osteoporosis, a nonsystemic treatment would be preferable. Zoledronate was then grafted to hydroxyapatite (HA) coating of titanium implants. The implants were inserted in rat condyles with various zoledronate concentrations. A positive concentration-dependent effect was observed on the peri-implant bone density and on different histomorphometric parameters. Importantly for the outcome of the implants, the mechanical fixation was increased by the local presence of zoledronate. The obtained results open the way of an easy transformation of currently existing HA-coated implants by grafting bisphosphonate onto the coating in order to increase their service life in the patients.

Animals↗
PubMed2004

Peri-implant bone remodeling after total hip replacement combined with systemic alendronate treatment: a finite element analysis.

In order to decrease the peri-implant bone loss during the life-time of the implant, oral use of anti-osteoporosis drugs (like bisphosphonates) has been suggested. In this study, bone remodeling parameters identified from clinical trials of alendronate were used to simulate the effect of those drugs used after total hip arthroplasty on the peri-implant bone density. Results of the simulation show that the oral administrated drugs increase bone density around the implant and decreases, at the same time, the micromovements between the implant and the surrounding bone tissue. Incorporation of drug effect in numerical studies of bone remodeling is a promising tool especially to predetermine safe bisphosphonate doses that could be used with orthopedic implants.

Administration, Oral↗
PubMed2002

The psychological effects of exposure to mixed organic solvents on car painters.

PURPOSE: Interest in diseases of the nervous system resulting from occupational exposure to mixed organic solvents has greatly increased. The aim of our study was to identify preclinical effects of low-level chronic solvent exposure on the central nervous system in car painters by assessing their cognitive performance. METHODS: This psychological study involved 169 clinically healthy male volunteers (84 car painters and 85 controls) and is part of a comprehensive study investigating effects of solvent exposure. The test battery included paper-pencil tests (vocabulary test, block design test, c.i., d2 test), computer-based tests (digit span test, simple-choice reaction time test), and a questionnaire to assess the participants' mental state. RESULTS: Car painters with long-term exposure to solvents showed psychological deviations such as deficits in concentration, memory and reaction time compared to unexposed subjects. The significant differences between the two groups were confirmed by multivariate statistical analysis. CONCLUSIONS: Our study displayed psychological effects associated with long-term solvent exposure in concentrations below German threshold limit values. These findings emphasize the necessity to promote the resolute compliance with occupational safety and health regulations in affected companies.

Adult↗
PubMed2002

Hospitalization vs. outpatient care in the management of triplet gestations.

OBJECTIVE: To compare the course and outcome of triplet gestations under a preventive care strategy that includes hospitalization, surveillance, bed rest, and daily specialized care from the beginning of the second trimester, with pregnancies managed according to the Croatian standard outpatient care protocol for multiplets. METHODS: A retrospective study of 79 triplet pregnancies. Preventive hospitalization from the beginning of the second trimester, with complete bed rest and all necessary interventions, was chosen by 55 women (Group I). The remaining 24 women (Group II) elected the standard outpatient protocol for multiple pregnancies. Outpatient management with prophylactic bed rest was initiated at home as soon as the multiple pregnancy was diagnosed. After 28 weeks of gestation, all outpatients were hospitalized until delivery irrespective of symptoms. RESULTS: There was no difference between the groups regarding maternal age, race, pre-pregnancy weight and height, weight gain during the first 24 weeks of pregnancy, or the proportion of pregnancies achieved with assisted reproductive technology. Four out of 55 women (7.2%) from Group I and 4 out of 24 women (12.5%) from Group II had monochorionic triplet pregnancies (P=n.s.). Nulliparity was more frequent in Group I than in Group II (P=0.006). Elective cesarean delivery was significantly more frequent in Group I (46 out of 55 gestations, 72.7%) than in Group II (9 out of 24 gestations, 37.5%), P=0.024. Gestational age at delivery and mean birth weight were significantly higher in Group I than in Group II (P<0.001). Deliveries up to 28 weeks of pregnancy were infrequent in Group I (P=0.02). Thirty-three gestations in Group I (60%) and 6 (25%) in Group II had a duration of 33-36 weeks (P<0.001). Two out of 55 triplet gestations in Group I (3.6%) and 4 out of 24 in Group II (16.7%) ended in spontaneous abortion (P=0.053). The survival of the three triplets was more frequent in Group I than in Group II (P=0.048). For gestations reaching 24 weeks or more, the fetal and perinatal death rate was significantly lower in Group I (P<0.001). In Group I the intrauterine death rate for fetuses weighing 1500 g or less was also significantly lower (P=0.007), and the early neonatal death rate was almost half (15.8 vs. 28.9%, P=0.157). There were no differences in other pregnancy complications between the two groups except significantly more frequent preterm premature rupture of membranes and preterm labor requiring parenteral tocolysis in Group II (P=0.042 and 0.036, respectively), and significantly more frequent fetal growth retardation in Group I (P<0.001). CONCLUSION: Preventive hospitalization offers a better outcome for triplets even though prolonged hospitalization and all other procedures necessary to achieve optimal pregnancy outcome are also offered in the Croatian standard outpatient care protocol for multiplet pregnancies.

Ambulatory Care↗
PubMed2002

Expression and dimerization of the rat activin subunits betaC and betaE: evidence for the ormation of novel activin dimers.

Activins are cytokines of the transforming growth factor beta family, which plays a central role in the determination of cell fate and the regulation of tissue balance. Family members are composed of two subunits and this dimerization is critical for liganding their cognate receptors and execution of proper functions. In the current study we focused on the localization of activin betaA, betaB, betaC and betaE subunits in the adult rat and analyzed the composition of putative activin beta dimers. By dissecting tissue distribution of various activins, we found that the liver, in particular the hepatocytes, is the major source for activin betaC and betaE transcripts, since other tissues almost failed to express these isoforms. In sharp contrast, the emergence of activin betaA and betaB appeared ubiquitous. Using a highly selective proteome approach, we were able to identify homo- as well as heterodimers of individual activin subunits, indicating a high redundancy of ligand composition. Certainly, this broad potential to homo- and heterodimerize has to be considered in future studies on activin function.

Activins↗
PubMed2001

[Ultrasound diagnosis of face and neck organs].

Sonography of the neck and face is highly suited for confirming visible, palpable or generally tentative findings. A method of performing a systematic examination will be described in detail and followed by numerous examples descriptive of soft tissue pathologies of the face, salivary glands and lymph nodes. The thyroid gland will be dealt with in a different report. The criterion that applied to all masses was that it was only possible to render a tentative diagnosis to be subsequently confirmed by sonography-guided fine-needle aspiration. Histological follow-up, however, was never excluded. If a finding could not be narrowed down by sonography, the next step was to use computerized or nuclear magnetic resonance imaging.

Facial Neoplasms↗
PubMed2001

Isolation of Escherichia coli mRNA and comparison of expression using mRNA and total RNA on DNA microarrays.

Bacterial messenger RNA (mRNA) is not coherently polyadenylated, whereas mRNA of Eukarya can be separated from stable RNAs by virtue of polyadenylated 3'-termini. We have developed a method to isolate Escherichia coli mRNA by polyadenylating it in crude cell extracts with E. coli poly(A) polymerase I and purifying it by oligo(dT) chromatography. Differences in lacZRNA levels were similar with purified mRNA and total RNA in dot blot hydridizations for cultures grown with or without gratuitous induction of the lactose operon. More broadly, changes in gene expression upon induction were similar when cDNAs primed from mRNA or total RNA with random hexanucleotides were hydridized to DNA microarrays for the E. coli genome. Comparable signal intensities were obtained with only 1% as much oligo(dT)-purified mRNA as total RNA, and hence in vitro poly(A) tailing appears to be selective for mRNA. These and additional studies of genome-wide expression with DNA microarrays provide evidence that in vitro poly(A) tailing works universally for E. coli mRNAs.

Cell Extracts↗
PubMed2001

[Microbiological and clinical effects of selective bowel decontamination in transthoracic resection of carcinoma of the esophagus and cardia].

INTRODUCTION: Surgical therapy of carcinoma of the esophagus or cardia by transthoracic esophageal resection is associated with a high morbidity in which nosocomial infections have a great importance. This study investigates the influence of prophylactic selective bowel decontamination on the course and results of transthoracic resection of the esophagus. METHODS: Seventy patients with carcinoma of the esophagus and cardia were included in this prospective and partially randomized study at the University of Heidelberg. Twenty-five patients received prophylactically selective bowel decontamination with tobramycin, polymyxin B and amphotericin B. The treatment course was documented uniformly. In addition, microbiological screening was performed by swab examinations of nose, throat and anus, by urine and blood cultures, and the documentation of results of additional microbiological diagnostic studies. RESULTS: Bacteriological screening confirmed a reduction in infectious agents and a change of their spectrum in the respiratory and digestive tract without an increase in multiresistant bacteria. Patients who received selective bowel decontamination had a lower infection rate, a shorter artificial respiration period and a shorter intensive care stay without statistically significant differences. The mortality rate was 4% vs 9% in the control group (95% confidence interval -0.172-0.116). CONCLUSION: This study confirms the feasibility and microbiological effectiveness of selective bowel decontamination in the context of surgical therapy which is associated with a high nosocomial infection rate. The result of the clinical treatment seems slightly more favorable in the treatment group. Decisive are complications caused by surgery which fundamentally determine the clinical course and frequently cause infectious complications. The prophylactic use of selective bowel decontamination may be useful in patients with an increased risk of prolonged ventilation support or colon interposition but it is not to be generally recommended.

Aged↗
PubMed2001

Comparative gene expression profiles following UV exposure in wild-type and SOS-deficient Escherichia coli.

The SOS response in UV-irradiated Escherichia coli includes the upregulation of several dozen genes that are negatively regulated by the LexA repressor. Using DNA microarrays containing amplified DNA fragments from 95.5% of all open reading frames identified on the E. coli chromosome, we have examined the changes in gene expression following UV exposure in both wild-type cells and lexA1 mutants, which are unable to induce genes under LexA control. We report here the time courses of expression of the genes surrounding the 26 documented lexA-regulated regions on the E. coli chromosome. We observed 17 additional sites that responded in a lexA-dependent manner and a large number of genes that were upregulated in a lexA-independent manner although upregulation in this manner was generally not more than twofold. In addition, several transcripts were either downregulated or degraded following UV irradiation. These newly identified UV-responsive genes are discussed with respect to their possible roles in cellular recovery following exposure to UV irradiation.

Bacterial Proteins↗
PubMed2000

[Cervicofacial necrotizing fasciitis].

INTRODUCTION: Necrotising fasciitis is still a severe disease whose outcome is occasionally fatal. METHODS: Between August 1994 and August 1998, 6 patients with necrotising fasciitis, 5 in the neck area and one in the facial area, were treated. The source of the infection was odontogenic in 3 cases, pharyngeal in 2 and an insect sting in the left upper eyelid in one case. RESULTS: Following evaluation by CT scan, immediate surgical exploration with debridement and drainage was performed. Revision proved necessary in most cases. One patient suffered severe complications. Median stay in the intensive care unit was 7 days and in hospital 20 days. DISCUSSION: Deep and extensive neck infections require investigation by CT scan. All affected areas must be explored and drained immediately, including thoracotomy if mediastinitis is present. Apart from appropriate antibiotic therapy, the further course of the disease should be carefully monitored to detect further spread of the infection as well as complications.

Adult↗
PubMed1999

Reinforcement of osteosynthesis screws with brushite cement.

The fixation of osteosynthesis screws remains a severe problem for fracture repair among osteoporotic patients. Polymethyl-methacrylate (PMMA) is routinely used to improve screw fixation, but this material has well-known drawbacks such as monomer toxicity, exothermic polymerization, and nonresorbability. Calcium phosphate cements have been developed for several years. Among these new bone substitution materials, brushite cements have the advantage of being injectable and resorbable. The aim of this study is to assess the reinforcement of osteosynthesis screws with brushite cement. Polyurethane foams, whose density is close to that of cancellous bone, were used as bone model. A hole was tapped in a foam sample, then brushite cement was injected. Trabecular osteosynthesis screws were inserted. After 24 h of aging in water, the stripping force was measured by a pull-out test. Screws (4.0 and 6.5 mm diameter) and two foam densities (0.14 and 0.28 g/cm3) were compared. Cements with varying solid/liquid ratios and xanthan contents were used in order to obtain the best screw reinforcement. During the pull-out test, the stripping force first increases to a maximum, then drops to a steady-state value until complete screw extraction. Both maximum force and plateau value increase drastically in the presence of cement. The highest stripping force is observed for 6.5-mm screws reinforced with cement in low-density foams. In this case, the stripping force is multiplied by 3.3 in the presence of cement. In a second experiment, cements with solid/liquid ratio ranging from 2.0 to 3.5 g/mL were used with 6.5-mm diameter screws. In some compositions, xanthan was added to improve injectability. The best results were obtained with 2.5 g/mL cement containing xanthan and with 3.0 g/mL cements without xanthan. A 0.9-kN maximal stripping force was observed with nonreinforced screws, while 1.9 kN was reached with reinforced screws. These first results are very promising regarding screw reinforcement with brushite cement. However, the polyurethane foam model presents noninterconnected porosity and physiological liquid was not modelized.

Bone Cements↗
PubMed1998

Disaccharides permeases: constituents of xylanolytic and mannanolytic systems of Aureobasidium pullulans.

Aureobasidium pullulans, a yeast-like microorganism was found to produce mannobiose permease and xylobiose permease, transporting beta-1,4-mannobiose or beta-1,4-xylobiose into the cells from extracellular media. Both permeases are induced by the same inducers as the corresponding hemicellulolytic enzyme systems. Mannobiose permease is induced by beta-1,4-mannobiose or is formed in the cells growing on mannan (inducers of beta-mannanolytic enzymes) and xylobiose permease is induced by d-xylose, beta-1,4-xylobiose or during the growth on xylan (inducers of xylanolytic enzymes). The permeases are energy dependent, synthesized de novo and their activities are inhibited by d-glucose. Since mannobiose permease transports beta-1,4-mannobiose, xylobiose permease appears to be less specific and transports beta-1,4-mannobiose, beta-1,4-xylobiose and methyl beta-d-xylopyranoside. Methyl beta-d-mannopyranoside or methyl beta-d-xylopyranoside serve as less efficient inducers of the corresponding permeases than beta-1,4-mannobiose or beta-1, 4-xylobiose.

Disaccharides↗
PubMed1998

[Potentialities and limitations of hypnosis for the treatment of pain].

With regard to the potentialities of hypnosis for the treatment of pain, relevant studies on hypnotic pain control are discussed. Studies with experimentally produced pain unanimously show that hypnosis is effective in controlling pain, whereas clinical studies are much more ambiguous in this respect. Three basic strategies of hypnotic pain control are outlined to which the different techniques can be subsumed: dissociative, associative, and symbolic strategies. Accountable for the limitations of hypnosis are some issues like hypnotic state, hypnotizability, rapport, hypnotic techniques, and pain as a multifactorial process. These issues are discussed and their contribution to contraindications are outlined. Especially the differences between symptom- and problem-oriented hypnotic approaches are highlighted.

English Abstract↗
PubMed1998

[Ergo-ophthalmologic problems of electronic display devices].

The paper approaches the problem of activity in front of a display. The authors show the compounds of an electronic device, theirs effects on visual acuity of the worker and the condition that are needed for visual comfort. Ergo-ophthalmologically it is important to examine periodically all the employers that use displays.

Computer Terminals↗