Cytocompatibility evaluation of different biodegradable magnesium alloys with human mesenchymal stem cells.

In the last few years, the use of biodegradable magnesium (Mg) alloys has evoked great interest in the orthopedic field due to great advantages over long-term implant materials associated with various side effects like allergy and sensitization and consequent implant removal surgeries. However, degradation of these Mg alloys results in ion release, which may cause severe cytotoxicity and undesirable complications after implantation. In this study, we investigated the cytological effects of various Mg alloys on cells that play an important role in bone repair. Eight different magnesium alloys containing varying amounts of Al, Zn, Nd and Y were either incubated directly or indirectly with the osteosarcoma cell line Saos-2 or with uninduced and osteogenically-induced human mesenchymal stem cells (MSCs) isolated from bone marrow specimens obtained from the femoral shaft of patients undergoing total hip replacement. Cell viability, cell attachment and the release of ions were investigated at different time points in vitro. During direct or indirect incubation different cytotoxic effects of the Mg alloys on Saos-2 cells and osteogenically-induced or uninduced MSCs were observed. Furthermore, the concentration of degradation products released from the Mg alloys differed. Overall, Mg alloys MgNd2, MgY4, MgAl9Zn1 and MgY4Nd2 exhibit good cytocompatibility. In conclusion, this study reveals the necessity of cytocompatibility evaluation of new biodegradable magnesium alloys with cells that will get in direct contact to the implant material. Furthermore, the use of standardized experimental in vitro assays is necessary in order to reliably and effectively characterize new Mg alloys before performing in vivo experiments.

Peel bond strength between 3D printing tray materials and elastomeric impression/adhesive systems: A laboratory study.

OBJECTIVES: The present study aimed to evaluate the bonding between three 3D printed custom tray materials and three elastomeric impression/adhesive systems using the peel test. METHODS: Test blocks were 3D printed by three different technologies using Dental LT, FREEPRINT tray, and polylactide (PLA) tray materials. The reference test blocks were conventionally fabricated with Zeta Tray LC, a light-curing resin. The surface topographies of the four tray materials were investigated by scanning electron microscopy (SEM) analyses and roughness measurements. The peel bond strength between the four tray materials and three impression/adhesive systems, vinylsiloxanether (VSXE), vinyl polysiloxane (VPS), and polyether (PE), was measured (n=12 per group). The peeling failure modes and rupture sites were identified microscopically. RESULTS: The four tray materials featured different surface topographies. The peel bond strength was not significantly different with VSXE and PE, but PLA and the reference showed higher peel bond strength with VPS than the Dental LT and FREEPRINT tray (p<0.05). The rupture site of adhesive failure in all groups was partly at the adhesive-impression material interface and partly within the adhesive but never at the adhesive-tray material interface. SIGNIFICANCE: The 3D printed tray materials can achieve satisfactory chemical compatibility with the adhesives of VSXE, VPS, and PE. Surface topographies generated by the 3D printing technologies may affect bonding. Generally, 3D printed tray materials can provide clinically adequate bond strength with the elastomeric impression/adhesive systems. PLA is recommended for bonding with VPS when severe impression removal resistance is detected.

Conservation tillage.

Conservation production systems combine tillage and planting practices to reduce soil erosion and loss of water from farmland. Successful conservation tillage practices depend on the ability of farm managers to integrate sound crop production practices with effective pest management systems. More scientific information is needed to determine the relations between tillage practices and physical, chemical, and biological soil factors that affect plant and pest ecology. There is a need to devise improved pest management strategies for conservation tillage and to better understand the impact of conservation tillage on water-quality, especially as it is related to use of agricultural chemicals. While savings in fuel, labor, and soil have induced many farmers to adopt conservation tillage, improved methods and equipment should increase adoption even more.

Comparative evaluation of topographical data of dental implant surfaces applying optical interferometry and scanning electron microscopy.

OBJECTIVE: Comparability of topographical data of implant surfaces in literature is low and their clinical relevance often equivocal. The aim of this study was to investigate the ability of scanning electron microscopy and optical interferometry to assess statistically similar 3-dimensional roughness parameter results and to evaluate these data based on predefined criteria regarded relevant for a favorable biological response. METHODS: Four different commercial dental screw-type implants (NanoTite Certain Prevail, TiUnite Brånemark Mk III, XiVE S Plus and SLA Standard Plus) were analyzed by stereo scanning electron microscopy and white light interferometry. Surface height, spatial and hybrid roughness parameters (Sa, Sz, Ssk, Sku, Sal, Str, Sdr) were assessed from raw and filtered data (Gaussian 50µm and 5µm cut-off-filters), respectively. Data were statistically compared by one-way ANOVA and Tukey-Kramer post-hoc test. For a clinically relevant interpretation, a categorizing evaluation approach was used based on predefined threshold criteria for each roughness parameter. RESULTS: The two methods exhibited predominantly statistical differences. Dependent on roughness parameters and filter settings, both methods showed variations in rankings of the implant surfaces and differed in their ability to discriminate the different topographies. Overall, the analyses revealed scale-dependent roughness data. Compared to the pure statistical approach, the categorizing evaluation resulted in much more similarities between the two methods. SIGNIFICANCE: This study suggests to reconsider current approaches for the topographical evaluation of implant surfaces and to further seek after proper experimental settings. Furthermore, the specific role of different roughness parameters for the bioresponse has to be studied in detail in order to better define clinically relevant, scale-dependent and parameter-specific thresholds and ranges.

End group analysis of yeast fatty acid synthetase.

The purified yeast fatty acid synthetase complex has been subjected to amino and carboxyl terminal amino acid end group analysis. Amino end groups were studied by Edman degradation and by dansylation of the sodium dodecyl sulfate- or urea-denatured complex. No N-terminal amino acid could be identified by either method. C-terminal amino acids were investigated by tritium labeling and by digestion of the complex with carboxypeptidases A and B. By both methods, the two amino acids valine and lysine were consistently identified as the C-termini of two different polypeptide chains. After separation of the fatty acid synthetase subunits A and B by sodium dodecyl sulfate polyacrylamide gel electrophoresis lysine was identified as the C-terminus of subunit A and valine as that of subunit B. The results are interpreted as evidence that the yeast fatty acid synthetase complex is basically composed of two nonidentical and multifunctional polypeptide chains.

Dose escalation of cyclophosphamide in patients with breast cancer: consequences for pharmacokinetics and metabolism.

PURPOSE: The alkylating anticancer agent cyclophosphamide (CP) is a prodrug that undergoes a complex metabolism in humans producing both active and inactive metabolites. In parallel, unchanged CP is excreted via the kidneys. The aim of this study was to investigate the influence of dose escalation on CP pharmacokinetics and relative contribution of activating and inactivating elimination pathways. PATIENTS AND METHODS: Pharmacokinetics of CP were assessed in 12 patients with high-risk primary breast cancer who received an adjuvant chemotherapy regimen that included four courses of conventional-dose CP (500 mg/m2 over 1 hour every 3 weeks) followed by one final course of high-dose CP (100 mg/kg over 1 hour). Plasma concentrations of CP were analyzed by high-performance liquid chromatography (HPLC), 24-hour urinary concentrations of CP, and its inactive metabolites (carboxyphosphamide, dechloroethylcyclophosphamide [dechlorethylCP], ketocyclophosphamide [ketoCP]) were determined by 31-phosphorus-nuclear magnetic resonance (31P-NMR)-spectroscopy. RESULTS: There was no difference in dose-corrected area under the concentration-time curve (AUC) (216 v 223 [mumol.h/[mL.g]), elimination half-life (4.8 v 4.8 hours), systemic clearance (79 v 77 mL/min) and volume of distribution (0.49 v 0.45 L/kg) of CP between conventional- and high-dose therapy, respectively. However, during high-dose chemotherapy, we observed a significant increase in the renal clearance of CP (15 v 23 mL/min; P < .01) and in the formation clearance of carboxyphosphamide (7 v 12 mL/min; P < .05) and dechloroethylCP (3.2 v 4.2 mL/min; P < .05), whereas metabolic clearance to ketoCP remained unchanged (1.3 v 1.2 mL/min). Consequently, metabolic clearance to the remaining (reactive) metabolites decreased from 52 to 38 mL/min (P < .001). The relative contribution of the different elimination pathways to overall clearance of CP demonstrated wide interindividual variability. CONCLUSION: Overall pharmacokinetics of CP are apparently not affected during eightfold dose escalation. However, there is a shift in the relative contribution of different clearances to systemic CP clearance in favor of inactivating elimination pathways, thereby indicating saturation of bioactivating enzymes during dose escalation. Besides individual enzyme capacity, hydration and concomitant medication with dexamethasone modulated CP disposition.

Antidepressants for the treatment of generalized anxiety disorder. A placebo-controlled comparison of imipramine, trazodone, and diazepam.

OBJECTIVE: The current study examines whether antidepressants, contrary to current thinking, are safe and effective treatments for generalized anxiety disorder (GAD) not complicated by depression or panic disorder. DESIGN: Randomized, double-blind, placebo-controlled, flexible-dose, 8-week treatment study comparing imipramine hydrochloride (mean maximum daily dose, 143 mg), trazodone hydrochloride (255 mg), and diazepam (26 mg). PATIENTS: Two hundred thirty patients with a DSM-III diagnosis of GAD in whom major depression and panic disorder has been excluded, and who had a Hamilton Anxiety Scale total score of at least 18. SETTING: Seventy-five percent of patients were treated in family practice settings in the community, with the remainder treated in psychiatric practices, either academic or private. RESULTS: Patients treated with diazepam showed the most improvement in anxiety ratings during the first 2 weeks of treatment, with somatic symptoms being most responsive. From week 3 through week 8 trazodone achieved comparable, and imipramine somewhat better, anxiolytic efficacy when compared with diazepam, with psychic symptoms of tension, apprehension, and worry being more responsive to the antidepressants. Among completers, moderate to marked improvement was reported by 73% of patients treated with imipramine, 69% of patients treated with trazodone, 66% of patients treated with diazepam, but only 47% of patients treated with placebo. Overall, patients treated with antidepressants reported a higher rate of adverse effects than diazepam-treated patients, but attention rates were the same across all treatments. CONCLUSIONS: The results of the study need replication, but suggest a potentially important role for antidepressants, particularly imipramine, in patients suffering from GAD.

Maintenance drug treatment of panic disorder. I. Results of a prospective, placebo-controlled comparison of alprazolam and imipramine.

One hundred six patients diagnosed according to DSM-III as suffering from agoraphobia with panic disorder, panic disorder with limited phobic avoidance, or uncomplicated panic disorder entered an acute 8-week treatment phase. Patients who improved received an additional 6 months' maintenance treatment. Significantly more patients treated with alprazolam than with imipramine hydrochloride or placebo remained in therapy and experienced panic attack and phobia relief during the acute treatment phase. During the maintenance phase, neither tolerance nor daily dose increase was observed. All patients who completed the maintenance phase (27 in the alprazolam group, 11 in the imipramine group, and 10 in the placebo group) were panic free at the end of 8 months of study treatment. Alprazolam therapy was effective and well tolerated at a mean daily dose of 5.7 mg. Imipramine hydrochloride (175 mg/d) also produced significant panic relief but was associated with poor patient acceptance.

Maintenance drug treatment for panic disorder. II. Short- and long-term outcome after drug taper.

Forty-eight patients with panic disorder completing 8 months of maintenance treatment with alprazolam (mean dose, 5.2 mg [n = 27]), imipramine hydrochloride (mean dose, 175 mg [n = 11]), or placebo (mean dose, 8.0 pills [n = 10]) underwent a gradual taper from medication over a 4-week period. A withdrawal syndrome was observed in almost all alprazolam-treated patients but in only a few imipramine- or placebo-treated patients. The clinical worsening of withdrawal symptoms after discontinuation tended to subside over the course of 3 medication-free weeks, but 33% of alprazolam-treated patients were unable to discontinue their medication regimen successfully. Severity of panic attacks at baseline but not daily alprazolam dose appeared as a significant independent predictor of taper difficulty. Forty-nine percent of the total study population continue to receive drug therapy: 82% alprazolam and 18% imipramine. Among patients who received alprazolam during study treatment and at follow-up, the mean daily dose was substantially reduced (6.1 vs 1.6 mg [n = 14]). At follow-up, after 1 year of naturalistic treatment for panic symptoms and combining 8-month completers and study dropouts, there were no significant differences in remission (68% to 71%) or in antipanic medication intake (39% to 56%) at follow-up for the three original treatment groups. However, 8-month study completers compared with study dropouts had a significantly higher remission rate (85% vs 55%).

Long-term treatment of anxiety and risk of withdrawal. Prospective comparison of clorazepate and buspirone.

Risk of withdrawal was investigated in a prospective, double-blind comparison of clorazepate dipotassium, a benzodiazepine with a long half-life, and the nonbenzodiazepine buspirone hydrochloride in the long-term treatment of anxious outpatients. Patients were treated with therapeutic doses of clorazepate dipotassium (15 to 60 mg/d) or buspirone hydrochloride (10 to 40 mg/d) for six continuous months before their tranquilizer therapy was blindly and abruptly stopped. There was a significant increase in symptom severity consistent with a withdrawal reaction for the clorazepate group but not the buspirone group. For the clorazepate group, there was a suggestion that previous discontinuous exposure to benzodiazepines might sensitize patients to subsequent withdrawal effects. For the buspirone group, a higher dropout rate raised questions about patient satisfaction with therapy in this rather chronically anxious population.

Long-term therapeutic use of benzodiazepines. II. Effects of gradual taper.

We compared the effect on withdrawal severity and acute outcome of a 25% per week taper of short half-life vs long half-life benzodiazepines in 63 benzodiazepine-dependent patients. Patients unable to tolerate taper were permitted to slow the taper rate. Ninety percent of patients experienced a withdrawal reaction, but it was rarely more than mild to moderate. Nonetheless, 32% of long half-life and 42% of short half-life benzodiazepine-treated patients were unable to achieve a drug-free state. The most difficulty was experienced in the last half of taper. Baseline personality, high Eysenck neuroticism, female sex, and mild-to-moderate alcohol use were found to be more significant predictors of withdrawal severity than the daily benzodiazepine dose or benzodiazepine half-life. These findings suggest that personality factors contribute significantly to the patient's difficulties with gradual benzodiazepine discontinuation of therapeutic doses of benzodiazepines.

Long-term therapeutic use of benzodiazepines. I. Effects of abrupt discontinuation.

We compared the effect of abrupt discontinuation of therapeutic doses of short half-life and long half-life benzodiazepines in 57 benzodiazepine-dependent patients (daily use, greater than 1 year). Despite the use of a mean daily dose of 14.1 mg of diazepam equivalents, there were notable residual symptoms of anxiety and depression present at intake (Hamilton Rating Scale for Anxiety score, 17.0; Hamilton Rating Scale for Depression score, 14.0). Benzodiazepine intake was stabilized for 3 weeks before double-blind assignment to placebo (n = 47), or continued benzodiazepine use (n = 10). Clinical assessments were performed daily, including benzodiazepine plasma levels. Depending on the outcome criteria used, anywhere from 58% to 100% of patients were judged to have experienced a withdrawal reaction, with a peak severity at 2 days for short half-life and 4 to 7 days for long half-life benzodiazepines. Relapse onto benzodiazepines occurred in 27% of patients who were receiving long half-life benzodiazepines and in 57% of patients who were receiving short half-life benzodiazepines. Baseline predictors of relapse were nonpanic diagnoses, a higher benzodiazepine dose, and a higher Eysenck neuroticism score. A short half-life and higher daily doses were associated with greater withdrawal severity, as were personality traits, such as dependency and neuroticism, less education and higher baseline levels of anxious and depressive symptoms. Patients who were able to remain free of benzodiazepines for at least 5 weeks obtained lower levels of anxiety than before benzodiazepine discontinuation. These results provide a detailed picture of the symptoms, time course, and multidimensional determinants of the benzodiazepine withdrawal syndrome.

Carbamazepine treatment in patients discontinuing long-term benzodiazepine therapy. Effects on withdrawal severity and outcome.

Forty patients with a history of difficulty discontinuing long-term, daily benzodiazepine therapy were randomly assigned, under double-blind conditions, to treatment with carbamazepine (200 to 800 mg/d) or placebo. A gradual taper (25% per week reduction) off benzodiazepine therapy was then attempted. Five weeks after taper, significantly more patients who had received carbamazepine than placebo remained benzodiazepine free, this despite the fact that no statistically significant differences in withdrawal severity could be demonstrated. Patients receiving carbamazepine reported a larger reduction in withdrawal severity than patients receiving placebo, but only at a trend level, and only on the daily patient-rated withdrawal checklist. Eleven patients (28%) required antidepressant therapy for depression or panic when assessed at 12-weeks follow-up. The results of this pilot investigation suggest that carbamazepine might have promise as an adjunctive drug therapy for the benzodiazepine withdrawal syndrome, particularly in patients receiving benzodiazepines in daily dosages of 20 mg/d or greater of diazepam equivalents.

Dose response in vivo to digoxin in normo-and hyperkalaemia: associated biochemical changes.

The effect of digoxin, at two different inotropic levels, was examined in normo- and hyperkalaemic dogs. For similar inotropic responses, normo- and hyperkalaemic dogs had similar levels of (Na+, K+)-ATPase inhibition and microsomal-bound digoxin.

Coating of ß-tricalcium phosphate scaffolds-a comparison between graphene oxide and poly-lactic-co-glycolic acid.

Bone regeneration in critical size defects is a major challenge in oral and maxillofacial surgery, and the gold standard for bone reconstruction still requires the use of autologous tissue. To overcome the need for a second intervention and to minimize morbidity, the development of new biomaterials with osteoinductive features is the focus of current research. As a scaffolding material, ß-tricalcium phosphate (ß-TCP) is suitable for bone regeneration purposes, although it does not carry any functional groups for the covalent immobilization of molecules. The aim of the present study was to establish effective coating variants for ß-TCP constructs to enable the biofunctionalization of anorganic blocks with different osteogenic molecules in future studies. We established working protocols for thin surface coatings consisting of polylactic-co-glycolic acid (PLGA) and graphene oxide (GO) by varying parameters. Surface properties such as the angularity and topography of the developed scaffolds were analyzed. To examine biological functionality, the adhesion and proliferation behavior of jaw periosteal cells (JPCs) were tested on the coated constructs. Our results suggest that PLGA is the superior material for surface coating of ß-TCP matrices, leading to higher JPC proliferation rates and providing a more suitable basis for further biofunctionalization in the field of bone tissue engineering.

Abnormal salivary cortisol levels in social phobic patients in response to acute psychological but not physical stress.

BACKGROUND: Little is known about the hypothalamic-pituitary-adrenal axis response to acute stressful behavioral challenges in patients with social phobia. METHODS: Eighteen patients with social phobia and 17 normal volunteers participated in two behavioral stressors: a speech task and physical exercise. RESULTS: Normal volunteers (n = 14) demonstrated a significant 50% increase in salivary cortisol levels to the speech task. Three nonresponding normal volunteers demonstrated a 17% decrease. In contrast, patients with social phobia demonstrated dichotomous changes. Seven social phobia patients demonstrated a significantly higher 90% increase in salivary cortisol to the speech task, whereas the remaining patients (n = 11) were nonresponders demonstrating a 32% decrease in cortisol. Both patient groups were significantly more anxious than the normal volunteers. In contrast to the response to a speech task, social phobics showed a cortisol response to physical exercise of similar magnitude as normal volunteers. CONCLUSIONS: The results indicated dichotomies in magnitude and in distribution of the cortisol response to a speech task between social phobia patients and normal volunteers. Social phobia patients responded differently than normal volunteers to a stressor associated with social evaluation but not to physical exercise. These results suggest adaptation of distinct biological processes specific to different stressful conditions in social phobia.

Pharmacokinetics and the pharmacodynamic action of midazolam in young and elderly patients undergoing tooth extraction.

OBJECTIVE: To determine whether age-dependent pharmacokinetic and pharmacodynamic alterations account for a more pronounced response to benzodiazepines among elderly patients. METHODS: Twelve young patients and 10 elderly patients received an intravenous dose of 0.05 or 0.03 mg/kg midazolan, respectively, before third molar extraction. Postoperative pain was treated with 30 mg dihydrocodeine. Serum concentrations of midazolam and sedative effects were monitored with visual analog scales and choice reaction time measurements for 6 hours. Test values above baseline were integrated, and pharmacokinetic-pharmacodynamic analysis was performed. Heart rate, blood pressure, arterial oxygen saturation, and amnesia also were assessed. RESULTS: There were no significant age-dependent differences in disposition of midazolam between young and elderly patients (apparent volume of distribution, 1.3 +/- 0.2 versus 1.1 +/- 0.4 L/kg; halflife, 3.3 +/- 1.5 hours versus 3.7 +/- 2.2 hours; total body clearance, 451 +/- 186 ml/min versus 343 +/- 137 ml/min). However, higher values of area under the effect curve (AUEC) and AUEC divided by area under the serum concentration-time curve (AUC) (sensitivity index) were observed among the elderly as follows: AUEC for reaction time (AUECRT) (573 versus 261; p = 0.042), AUEC for visual analog scale (AUECVAS) (37.7 versus 14.4; p = 0.011), AUECRT/AUC (6.3 versus 1.8; p = 0.007), and AUECVAS/AUC (0.40 versus 0.11; p = 0.009) compared with the young group. Likewise, mean concentration at half-maximal effect for sedation was lower (p = 0.025) among older patients (20.5 +/- 2.2 ng/ml) than among younger (29.7 +/- 6.6 ng/ml) patients. Amnesia was observed among 86% of patients and oxygen saturation was always 95% or more of basal value. There were no age-related differences in concentration of dihydrocodeine and its active metabolite dihydromorphine, but dihydromorphone levels were much lower in there intermediate metabolizers (455 to 879 fmol/l) and especially in five poor metabolizers (65 to 498 fmol/L) than among extensive metabolizer of cytochrome p450 2D6 (1604 to 6490 fmol/L). CONCLUSION: Elderly patients are more sensitive to the sedative action of midazolam than young patients, and the sensitivity is caused by age-dependent pharmacodynamic alterations. The age-adjusted doses used are both effective (for sedative amnesia) and safe (in terms of arterial oxygen saturation, heart rate, and blood pressure.

Failure of buspirone to manage benzodiazepine withdrawal.

Fifteen patients with 146 cumulative years of tranquilizer use were withdrawn from their benzodiazepine (nine gradually and six abruptly), and buspirone, a new nonbenzodiazepine anxiolytic, was substituted. The addition of buspirone did not appear to lessen the intensity of the withdrawal state. This finding supports preclinical studies indicating that buspirone has no clinically significant benzodiazepine receptor activity.

Insulin-induced hypoglycemia and panic attacks.

To investigate whether hypoglycemia might trigger panic attacks, the authors administered intravenous insulin to 10 patients with panic disorder. All subjects developed hypoglycemia but no panic anxiety. They reported symptoms of adrenergic hyperactivity but differentiated them from spontaneous panic attacks.

Multiple hormonal responses to insulin-induced hypoglycemia in depressed patients and normal volunteers.

Studies have shown that some depressed patients may demonstrate multiple hormonal response abnormalities after a neuroendocrine challenge test; this finding has suggested the strategy of measuring several hormones after an insulin tolerance test. The authors gave insulin tolerance tests to 72 depressed patients and 51 age- and sex-matched healthy volunteer control subjects and measured glucose, cortisol, prolactin, and human growth hormone (GH) responses. Although there were no differences between patients and control subjects in the mean decrease in glucose levels after the insulin tolerance test, depressed men demonstrated significantly lower prolactin and GH levels after the test.