Effect of surface finish on the osseointegration of laser-treated titanium alloy implants

It was the purpose of this study to examine the osseointegration of laser-textured titanium alloy (Ti6Al4V) implants with pore sizes of 100, 200, and 300 microm, specifically comparing 200-microm implants with polished and corundum-blasted surfaces in a rabbit transcortical model. Using a distal and proximal implantation site in the distal femoral cortex, each animal received all four different implants in both femora. The bone-implant interface and the newly formed bone tissue within the pores and in peri-implant bone tissue were examined 3, 6, and 12 weeks post-implantation by static and dynamic histomorphometry. Here we show that additional surface blasting of laser-textured Ti6Al4V implants with 200-microm pores resulted in a profound improvement in osseointegration, 12 weeks postimplantation. Although lamellar bone formation was found in pores of all sizes, the amount of lamellar bone within pores was linearly related to pore size. In 100-microm pores, bone remodeling occurred with a pronounced time lag relative to larger pores. Implants with 300-microm pores showed a delayed osseointegration compared with 200-microm pores. We conclude that 200 microm may be the optimal pore size for laser-textured Ti6Al4V implants, and that laser treating in combination with surface blasting may be a very interesting technology for the structuring of implant surfaces.     

Computerized Digital Imaging Techniques Provided by Digital X-ray Radiogrammetry as New Diagnostic Tool in Rheumatoid Arthritis

Purpose Our study evaluates digital x-ray radiogrammetry (DXR) and Radiogrammetry Kit (RK) as a new diagnostic method for the measurement of disease-related osteoporosis including quantification of joint space narrowing dependent on the severity of rheumatoid arthritis (RA). Materials and Methods A total of 172 unselected patients with RA underwent computerized measurements of bone mineral density (BMD) and metacarpal index (MCI) by DXR, as well as a semiautomated measurement of joint space distances at the metacarpal–phalangeal articulation (JSD-MCP 2–5), both were analyzed from plain radiographs of the nondominant hand. Results Correlations between DXR-BMD and DXR-MCI vs. parameters of RK were all significant (0.34 < R < 0.61; p < 0.01). An expected negative association was observed between RK parameters and the different scoring methods (−0.27 < R < −0.59). The maximum relative decrease in BMD vs. MCI as measured by DXR between the highest and lowest RA severity group was −27.7% vs. −27.5% (p < 0.01) for the modified Larsen Score, whereas the minimal value of relative DXR-BMD and DXR-MCI reduction could be documented for the Sharp Erosion Score (−20.8% vs. −26.8%; p < 0.01). The relative reduction of mean JSD-MCP using RK significantly varied from −25.0% (Sharp Erosion Score) to −41.2% (modified Larsen Score). In addition, an excellent reproducibility of DXR and RK could be verified. Conclusion DXR in combination with RK could be a promising, widely available diagnostic tool to supplement the different scoring methods of RA with quantitative data, allowing an earlier and improved diagnosis and more precision in determining disease progression.     

Group A Streptococci from carriage and disease in Portugal: evolution of antimicrobial resistance and T antigenic types during 2000-2002

In this study, we analyzed the antimicrobial resistance properties and T antigenic types of 511 isolates collected in Lisbon district, Portugal, from throat swabs of healthy subjects (n=341), during 2000-2002 and from diverse infection sites (n=170) of outpatients and inpatients, during 1999-2002. Erythromycin resistance was higher in tonsillitis/pharyngitis (27.4%) and skin infection isolates (21.1%), than in carriage and invasive isolates (相似文献   

Frontal lobe in vivo (31)P-MRS reveals gender differences in healthy controls, not in schizophrenics

Phosphorus-31 magnetic resonance spectroscopy ((31)P-MRS) has gained much interest in schizophrenia research in recent years since it allows the non-invasive measurement of high-energy phosphates and phospholipids in vivo. However, until now only differences in metabolite concentrations between certain brain areas of schizophrenic patients and healthy controls have been examined. We investigated the influence of gender on the concentrations of different phosphorus compounds. For this purpose, well-defined volumes in the frontal lobe of 32 healthy controls and 51 schizophrenic in-patients were examined with an image selected in vivo spectroscopy (ISIS) sequence on a whole-body scanner at 1.5 T. Healthy females exhibited increased values of inorganic phosphate (P(i)) and decreased values of phosphocreatine (PCr) in comparison to their male counterparts. In schizophrenic patients such gender differences were not present. Thus, the results can be interpreted in the sense that frontal energy demanding processes are enhanced in female compared to male healthy volunteers; schizophrenia seems to reduce these gender differences.     

Recommendations for the examination of peripheral nerve biopsies

 Peripheral nerve biopsy is now an established, valuable investigative procedure, but as it can give rise to significant residual symptoms it should only be undertaken after careful consideration of the indications and with informed consent from the patient. Nerve biopsies should only be processed and evaluated in a laboratory with the relevant particular expertise. It is generally recommended that a sural nerve biopsy be performed in combination with a muscle biopsy but not vice versa (muscle biopsies together with a nerve biopsy). Nerve biopsy is not the only means of sampling peripheral nerve tissue to study the peripheral nervous system. Examination of the innervation of the skin may be informative. The same is likely to be true for motor point muscle biopsy. Nerve biopsy is mainly used for morphology although molecular genetic techniques using fresh or archival nerve biopsies are increasingly available. Chemical analysis is undertaken mainly for research purposes. Received: 10 June 1997 / Accepted: 29 October 1997     

Effects of histamine H1-receptor blockade on respiratory and cardiac manifestation of systemic anaphylaxis

Summary In vivo anaphylaxis is associated with respiratory distress and cardiovascular failure. The present investigation was designed to further characterize respiratory and cardiac anaphylactic events. In guinea pigs, sensitization was produced by subcutaneous application of ovalbumin together with Freund's adjuvant. Fourteen days after sensitization, the effects of an intravenous infusion of ovalbumin were tested in the anesthetized artificially ventilated guinea pigs. The renewed application of the antigen induced an initial increase of left ventricular pressure which was followed by a rapid decrease 5 min after antigenic challenge. Enddiastolic left ventricular pressure increased within 3 min, thus indicating left ventricular pump failure. In the same time range, ECG recordings uniformly showed signs of acute myocardial ischemia. In addition, heart rate steadily decreased. All animals died within 15 min. Simultaneously with cardiac anaphylactic malfunction, severe arterial hypoxia and carbon dioxide retention occurred, revealing respiratory distress.Histamine is known as a potent bronchoconstrictor via histamine H₁-receptor stimulation. Administration of H₁-recpetor antagonists to improve respiration may therefore provide further information on the contribution of pulmonary malfunction to anaphylactic cardiovascular shock. Therefore, additional experiments were performed with sensitized guinea pigs pretreated with the histamine H₁-receptor blocker mepyramine. In these experiments the antigenic challenge induced a dissociation of cardiac and respiratory manifestation of anphylaxis. Despite inhibition of hypoxia and carbon dioxide retention, left ventricular pump failure and occurrence of myocardial ischemia were delayed but not suppressed.It is concluded that histamine is an important mediator of anaphylactic respiratory distress. However, vasoactive anaphylactic mediators other than histamine are primarily involved in anaphylactic cardiac malfunction occurring during the later phase of systemic anaphylaxis.Supported by grant Fe 250/1-1 from the Deutsche Forschungsgemeinschaft (DFG).     

Gemfibrozil absorption and elimination in kidney and liver disease

Summary The disposition of the lipid-lowering drug gemfibrozil was studied in patients with either renal (n= 8) or hepatic disease (n= 8) and compared to those of healthy volunteers (n= 6). Gemfibrozil was determined in plasma and urine by means of a HPLC method. Urine was also analyzed for gemfibrozil conjugates.Following oral administration of 900 mg gemfibrozil, maximal plasma levels of the parent drug were 46.1±15.8 g/ml, attained after 2.2±1.1 h. In chronic renal failure and in liver cirrhosis the plasma concentrations of gemfibrozil did not significantly differ from that of controls except in those patients who were comedicated with antacids. These patients had significantly lower C_max and AUC values. The elimination half-life of the drug was 1.5 h in controls, 2.4 h in renal failure, and 2.1 h in liver disease. In healthy volunteers, only 0.02 to 0.15% of the given dose was recovered in the urine as parent gemfibrozil, while conjugates made up 7–14%. In patients with renal failure also, only traces of parent gemfibrozil could be detected, and conjugates accounted for 0.5–9.8%. In those with liver disease, however, about 0.1–0.2% were recovered in urine as parent gemfibrozil and up to 50% as conjugates. Strikingly, the amount of excreted conjugates in the urine was positively correlated to the direct bilirubin plasma concentration. It can be concluded that the elimination of gemfibrozil is not significantly influenced by renal failure. However, comedication with antacids markedly reduced plasma disposition of the drug. Patients with severe liver disease excreted more conjugated gemfibrozil via the kidney than did healthy controls. Thus, transfer across the canalicular cell membrane to the bile duct, rather than drug metabolization, is primarily disturbed in liver disease. Gemfibrozil accumulation is unlikely to occur in either kidney or liver disease.Abbreviations Cl_r creatinine clearance (ml/min) - HPLC high pressure liquid chromatography - C_max maximal plasma concentration (g/ml) - t_max time (h) after which C_max is attained - k_e elimination rate constant (h^–1) - t_1/2 elimination half-life (h) - A_e amount of drug excreted into the urine (% of given dose) - MRT mean residence time (h) - AUMC area under the first moment curve (g h²/ml) - AUC area under the plasma level time curve (g·h/ml) - ANOVA analysis of variance The paper is gratefully dedicated to G.W. Löhr     

Scanning electron microscopic investigations of the human umbilical artery intima

Summary Umbilical cord arteries were investigated using a scanning electron microscope using different methods of preparation: Perfusion of one artery under pressure from a 100 cm water column caused artefacts and the preparatory work took at least 10 min after delivery. To shorten this time fully patent umbilical cords were double clamped and fixed immediately after birth. However, the removal of blood after fixation caused the endothelial layer to be lost. Therefore umbilical cords were double clamped, snap frozen and stored in liquid nitrogen until preparation. The endothelial lining of the fully patent umbilical artery at birth is composed of longitudinally arranged, spindleshaped cells, connected by cellular junctions. The basement membrane contains numerous gaps. Because of these gaps postnatal vasoconstriction causes herniation of the subendothelial myofibroblasts forming subendothelial vacuoles. The vacuoles produce displacement of the endothelial cell cytoplasm towards the vascular lumina resulting in protuberances and blebs on the endothelial cells. Rupture of vacuoles leads to crater-like injuries.Beneath the basement membrane a thin layer of myofibroblasts is arranged longitudinally. Oblique or transversely ordered bundles of myofibroblasts are interposed at wide and irregular intervals. These transverse bundles are able to trigger localized contraction rings called folds of Hoboken, the initial stage of postnatal arterial closure.     

Tick-borne encephalitis vaccines: past and present

Vaccines to protect against tick-borne encephalitis (TBE) are produced by two manufacturers and are widely used in European and Asian countries, where TBE virus is endemic. General trends in vaccine development during recent decades and extensive postmarketing experience resulted in several modifications to their formulations and practical implications for use. Modifications were made to the production process, such as the change of the virus master bank from mouse brain to primary cells; to the excipients, especially the stabilizers and preservative; and to include formulations for children. Additionally, a rapid vaccination schedule has been developed for persons who require a fast onset of protection. Recent data from clinical studies and postmarketing surveillance indicate that both vaccines are safe, efficacious and interchangeable. Further (major) changes to formulation or alternative targets for vaccine development are not anticipated in the next 5 years. Recent serologic studies indicate that the persistence of protective immunity was longer than expected. Thus, recommendations for prolongation of TBE booster intervals have been made in several European countries, and a harmonization for booster recommendations is predicted within the European Union. Based on epidemiologic trends, the use of TBE vaccines will continue to increase in all age groups, including children.