Fast Self-Healing at Room Temperature in Diels-Alder Elastomers

Despite being primarily categorized as non-autonomous self-healing polymers, we demonstrate the ability of Diels-Alder polymers to heal macroscopic damages at room temperature, resulting in complete restoration of their mechanical properties within a few hours. Moreover, we observe immediate partial recovery, occurring mere minutes after reuniting the fractured surfaces. This fast room-temperature healing is accomplished by employing an off-stoichiometric maleimide-to-furan ratio in the polymer network. Through an extensive investigation of seven Diels-Alder polymers, the influence of crosslink density on self-healing, thermal, and (thermo-)mechanical performance was thoroughly examined. Crosslink density variations were achieved by adjusting the molecular weight of the monomers or utilizing the off-stoichiometric maleimide-to-furan ratio. Quasistatic tensile testing, dynamic mechanical analysis, dynamic rheometry, differential scanning calorimetry, and thermogravimetric analysis were employed to evaluate the individual effects of these parameters on material performance. While lowering the crosslink density in the polymer network via decreasing the off-stoichiometric ratio demonstrated the greatest acceleration of healing, it also led to a slight decrease in (dynamic) mechanical performance. On the other hand, reducing crosslink density using longer monomers resulted in faster healing, albeit to a lesser extent, while maintaining the (dynamic) mechanical performance.

Crystalloid resuscitation in trauma patients: deleterious effect of 5L or more in the first 24h

BACKGROUND

Over-aggressive intravenous fluid therapy with crystalloids has adverse effects in trauma patients. We assessed the role of large-volume (≥5l) administration of crystalloids within 24h of injury as an independent risk-factor for mortality, in-hospital complications, and prolonged mechanical ventilation.

METHODS

A retrospective cohort analysis of adult trauma patients admitted to a level 1-trauma center between December 2011 and December 2012. Patient demographics, clinical and laboratory values, and total resuscitation fluid administered within the first 24h of injury were obtained. Outcomes included mortality, in-hospital complications and ventilator-days. Multivariable logistic regression and Poisson regression analyses were performed to investigate any association between the administration of ≥5L crystalloids with the aforementioned outcomes while controlling for selected clinical variables.

RESULTS

A total of 970 patients were included in the analysis. 264 (27%) received ≥5L of crystalloids in the first 24h of injury. 118 (12%) had in-hospital complications and 337 (35%) required mechanical ventilation. The median age was 46 years (interquartile range (IQR) 27-65) years and 73% (n = 708) were males. The median injury severity score (ISS) was 17 (IQR 9-25). Overall mortality rate was 7% (n = 67). Multivariable logistic regression analysis showed several variables independently associated with mortality (p < 0.05), including resuscitation with ≥5L crystalloid in the first 24h (adjusted odds ratio (aOR) 2.55), older age (aOR 1.03), higher ISS (aOR 1.09), and lower temperature (aOR 0.68). The variables independently associated with in-hospital complications (p < 0.05) were older age, longer ICU stay, and platelet transfusion within 24h of the injury. Need for mechanical ventilation was more common in patients who received ≥5L crystalloids (RR 2.31) had higher ISS (RR 1.02), developed in-hospital complications (RR 1.91) and had lower presenting temperature (RR 0.87).

CONCLUSION

Large-volume crystalloid resuscitation is associated with increased mortality and longer time ventilated, but not with in-hospital complications such as pneumonia and sepsis. Based on this data, we recommend judicious use of crystalloids in the resuscitation of trauma patients.

Optimal Dosage of Cyclopentolate 1% for Complete Cycloplegia: A Randomized Clinical Trial

PURPOSE

To determine the optimal dosage of cyclopentolate for adequate cycloplegia with minimal side effects.

METHODS

A prospective randomized clinical trial of patients 3.5 to 20 years of age referred to a strabismus clinic during a 1-year period. Eligible patients were randomly divided into three groups. In Group 1, the cycloplegic effect of one drop of cyclopentolate was compared with two drops; in Group 2, the effect of two drops was compared with three drops; and in Group 3, the effect of one drop was compared with three drops.

RESULTS

This study includes 192 eyes of 96 patients with a mean age of 11.0 +/- 5.7 years. Strabismus was present in 43 patients (44.8%). A total of 146 patients (76%) were hyperopic, 33 (17.2%) were myopic, and 13 (6.8%) were slightly hyperopic or myopic at the two stages of the study. Overall, only 16 eyes, including 9 eyes in Group 1 (16.4%), 2 eyes in Group 2 (3.2%), and 5 eyes in Group 3 (8.6%), had > or = 0.5 D difference in spherical equivalent refractive error at two stages of the study; however, intergroup differences were not statistically significant (p=0.16, chi-square test). Within each group, the percentage of eyes with <0.5 D difference was significantly greater than those with > or = 0.5 D difference (p<0.001 in all three groups, binomial test). Side effects were more prevalent using more frequent drops.

CONCLUSIONS

A single drop of cyclopentolate 1% suffices for cycloplegic refraction. There were less frequent side effects using one drop of cyclopentolate, compared to two or three drops.

Framework for assessing stewardship of the oral health system in Islamic Republic of Iran

This study designed a framework for assessing the stewardship function of the oral health system in Islamic Republic of Iran. The modified RAND Corporation/University of California Los Angeles (RAND-UCLA) Appropriateness Method was used in a 2-step process that combined literature evidence and the collective judgement of experts. After a comprehensive literature review, policy instruments related to stewardship components were extracted as candidate standards and categorized according to the 6 sub-functions of stewardship (accountability; defining strategic direction; alignment of policy objectives and organizational structure; regulation; intersectoral leadership; and generation of intelligence). Five key informants then rated the appropriateness of the 85 standards on a 5-point Likert scale. The 38 highest ranked standards, including at least 2 standards in each of the 6 sub-functions, formed a set of proposed standards for evaluating the current stewardship of oral health system. Piloting of the instrument will be reported separately.

Developing a policy guidance for financing dental care in Iran using the RAND Appropriateness Method

OBJECTIVE

This study aimed to provide recommendations on health care financing with special emphasis on dental care.

METHODS

The RAND Appropriateness Method was employed to obtain the collective opinion of a multidisciplinary panel of experts on a set of recommendation statements regarding Iranian dental care financing. An initial set of recommendations were identified from a literature review. Panel members, selected purposively and by peer nomination, each rated the appropriateness and necessity of the recommendations in a structured process of two rounds. Each recommendation was classified as inappropriate, uncertain, appropriate but not necessary, or appropriate and necessary according to the median rating score and the level of disagreement among the panellists.

RESULTS

Of 28 initial recommendations, 25 were agreed on as appropriate, of which 22 were considered as necessary. Altogether, these recommendations provide a holistic picture of an oral health system's financing in three domains: revenue collection, pooling of revenues and purchasing of dental services.

CONCLUSION

The policy guidance recommendations are intended to provide the Iranian oral health authorities with an evidence-base for financing dental care. The recommendations may be transferrable, at least in part, particularly to developing countries with similar hybrid health system structures. Finally, the method used to develop the recommendations can serve as a model for use elsewhere.

Reducing the absorbed dose in analogue radiography of infant chest images by improving the image quality, using image processing techniques

Radiographic inspection is one of the most widely employed techniques for medical testing methods. Because of poor contrast and high un-sharpness of radiographic image quality in films, converting radiographs to a digital format and using further digital image processing is the best method of enhancing the image quality and assisting the interpreter in their evaluation. In this research work, radiographic films of 70 infant chest images with different sizes of defects were selected. To digitise the chest images and employ image processing the two algorithms (i) spatial domain and (ii) frequency domain techniques were used. The MATLAB environment was selected for processing in the digital format. Our results showed that by using these two techniques, the defects with small dimensions are detectable. Therefore, these suggested techniques may help medical specialists to diagnose the defects in the primary stages and help to prevent more repeat X-ray examination of paediatric patients.

Stomatal vs. genome size in angiosperms: the somatic tail wagging the genomic dog?

BACKGROUND AND AIMS

Genome size is a function, and the product, of cell volume. As such it is contingent on ecological circumstance. The nature of 'this ecological circumstance' is, however, hotly debated. Here, we investigate for angiosperms whether stomatal size may be this 'missing link': the primary determinant of genome size. Stomata are crucial for photosynthesis and their size affects functional efficiency.

METHODS

Stomatal and leaf characteristics were measured for 1442 species from Argentina, Iran, Spain and the UK and, using PCA, some emergent ecological and taxonomic patterns identified. Subsequently, an assessment of the relationship between genome-size values obtained from the Plant DNA C-values database and measurements of stomatal size was carried out.

KEY RESULTS

Stomatal size is an ecologically important attribute. It varies with life-history (woody species < herbaceous species < vernal geophytes) and contributes to ecologically and physiologically important axes of leaf specialization. Moreover, it is positively correlated with genome size across a wide range of major taxa.

CONCLUSIONS

Stomatal size predicts genome size within angiosperms. Correlation is not, however, proof of causality and here our interpretation is hampered by unexpected deficiencies in the scientific literature. Firstly, there are discrepancies between our own observations and established ideas about the ecological significance of stomatal size; very large stomata, theoretically facilitating photosynthesis in deep shade, were, in this study (and in other studies), primarily associated with vernal geophytes of unshaded habitats. Secondly, the lower size limit at which stomata can function efficiently, and the ecological circumstances under which these minute stomata might occur, have not been satisfactorally resolved. Thus, our hypothesis, that the optimization of stomatal size for functional efficiency is a major ecological determinant of genome size, remains unproven.

Elevated plasma levels of interleukin-2 and soluble IL-2 receptor in ischemic heart disease

BACKGROUND

T-lymphocytes are present in significant numbers in the atherosclerotic plaque, but their role in the progression and pathogenesis of coronary syndromes remains poorly understood.

HYPOTHESIS

We sought to determine the relationship between T-lymphocyte activation and ischemic heart disease by measuring plasma levels of cytokines related to T-lymphocyte function in patients with stable and unstable angina.

METHODS

Plasma levels of interleukin-2 (IL-2) and soluble IL-2 receptor (sIL-2R) were measured in 105 patients: 66 with stable angina, 24 with unstable angina, and 15 healthy controls. Patients who presented to the cardiac catheterization laboratory with unstable or stable anginal syndromes for coronary angiography or percutaneous coronary intervention enrolled in the study.

RESULTS

Mean levels of IL-2 were significantly higher in patients with stable angina than in those with unstable angina. The differences between stable angina and control groups, or between unstable angina and control groups, were not statistically significant. Mean levels of slL-2R were significantly higher in patients with stable angina than in either patients with unstable angina or control patients.

CONCLUSIONS

Levels of IL-2 and sIL-2 receptor are significantly elevated in patients with stable angina, but not in patients with unstable angina. The contribution of T-lymphocytes to the development of both stable and unstable angina requires further investigation.

Distinct patterns of DeltaFosB induction in brain by drugs of abuse

The transcription factor DeltaFosB accumulates and persists in brain in response to chronic stimulation. This accumulation after chronic exposure to drugs of abuse has been demonstrated previously by Western blot most dramatically in striatal regions, including dorsal striatum (caudate/putamen) and nucleus accumbens. In the present study, we used immunohistochemistry to define with greater anatomical precision the induction of DeltaFosB throughout the rodent brain after chronic drug treatment. We also extended previous research involving cocaine, morphine, and nicotine to two additional drugs of abuse, ethanol and Delta(9)-tetrahydrocannabinol (Delta(9)-THC, the active ingredient in marijuana). We show here that chronic, but not acute, administration of each of four drugs of abuse, cocaine, morphine, ethanol, and Delta(9)-THC, robustly induces DeltaFosB in nucleus accumbens, although different patterns in the core vs. shell subregions of this nucleus were apparent for the different drugs. The drugs also differed in their degree of DeltaFosB induction in dorsal striatum. In addition, all four drugs induced DeltaFosB in prefrontal cortex, with the greatest effects observed with cocaine and ethanol, and all of the drugs induced DeltaFosB to a small extent in amygdala. Furthermore, all drugs induced DeltaFosB in the hippocampus, and, with the exception of ethanol, most of this induction was seen in the dentate. Lower levels of DeltaFosB induction were seen in other brain areas in response to a particular drug treatment. These findings provide further evidence that induction of DeltaFosB in nucleus accumbens is a common action of virtually all drugs of abuse and that, beyond nucleus accumbens, each drug induces DeltaFosB in a region-specific manner in brain.

Corneal topographic changes after scleral buckling

PURPOSE

To evaluate corneal topographic changes and induced corneal astigmatism after scleral buckling (SB).

METHODS

This interventional case series includes all patients who had undergone scleral buckling for rhegmatogenous retinal detachment (RRD) during a 1-year period. Patients were divided into four groups according to type and extent of scleral buckling which depended on the discretion of a retina specialist. Videokeratography was performed for all patients preoperatively and repeated 1 and 3 months after SB.

RESULTS

Thirty-nine eyes of 39 patients (29 male, 74.7%) with mean age of 50.35+/-20 years (range 13-80) were finally analyzed. There was no statistically significant difference among the groups in terms of preoperative corneal astigmatism, surface regularity index (SRI), surface asymmetry index (SAI), mean keratometry (mean K), and potential visual acuity (PVA ). Overall, preoperative mean K was 43.97+/-1.78 D, which reached 44.2+/-2.02 D and 43.92+/-2.16 D 1 and 3 months after the operation. Mean preoperative SRI was 0.58+/-0.4, which increased to 1.24+/-1.18 and 1.29+/-1.13 1 and 3 months after the operation respectively. Mean preoperative SAI was 0.39+/-0.21, which increased to 0.73+/-0.37 and 0.75+/-0.66 1 and 3 months after the procedure. Changes in SAI at 1 and 3 months following SB were significant (p values <0.001); however, these postoperative values were not significantly different. Mean preoperative PVA was 0.07+/-0.75 logMAR (equivalent to 20/20) but decreased to 0.24+/-0.25 (equivalent to 20/30) and 0.27+/-0.29 (equivalent to 20/40) 1 and 3 months after SB, respectively.

CONCLUSIONS

Significant changes in corneal topographic indices including increases in SRI and SAI and a concomitant decrease in PVA may occur after SB procedures. These induced changes must be considered and appropriately addressed postoperatively to provide the best possible corrected vision.

Effect of tranexamic acid on early postvitrectomy diabetic haemorrhage; a randomised clinical trial

AIMS

To evaluate the effect of tranexamic acid on early postvitrectomy haemorrhage in diabetic patients.

METHODS

In a clinical trial, 62 diabetic patients scheduled for vitrectomy were randomly assigned to two groups. The treatment group (32 eyes) received two doses of tranexamic acid (10 mg/kg) shortly before and after the operation intravenously, continued orally for 4 days (20 mg/kg/8 hours). The control group (30 eyes) received no medication. Both media clarity and visual acuity were compared during 4 weeks.

RESULTS

Four weeks after surgery visual acuity was low (< or =1 metre counting fingers) in 21.4%, moderate (>1 metre counting fingers but<20/200) in 14.3%, and good (> or =20/200) in 64.3% of the treated group. Corresponding figures in the control group were 26.1%, 26.1%, and 47.8%, respectively. These differences were of no statistical significance. The ratio of mild to severe vitreous haemorrhage during the first 4 days and after 4 weeks was 79% to 21% and 82% to 18% in the treatment group and 76.7% to 23.3% and 78.3% to 21.7% in the control group respectively, which showed no statistically significant difference.

CONCLUSION

Tranexamic acid, with the method of administration in this study, had no effect on reducing early postvitrectomy haemorrhage in diabetic patients.

Cerebrospinal fluid leakage during dacryocystorhinostomy in a patient with meningoencephalocele

PURPOSE

To report a rare case of cerebrospinal fluid leakage during dacryocystorhinostomy in a patient with Mobius syndrome and meningoencephalocele and to explain our experience in the management of this complication.

METHODS

A 9-year-old girl with a history of surgically repaired fronto-ethmoidal meningoencephalocele and bilateral canthopexy was diagnosed with Mobius syndrome and underwent sequential bilateral dacryocystorhinostomy and silicone intubation because of dysgenesis of the lacrimal drainage pathway.

RESULTS

Both dacryocystorhinostomies resulted in cerebrospinal fluid leakage, which spontaneously ceased with conservative management.

CONCLUSIONS

Dacryocystorhinostomy surgery in patients with a history of trauma or surgery or congenital defects around the base of the nose or lacrimal system may rarely result in cerebrospinal fluid leakage; thus an ophthalmologist should be familiar with its management.

Circulating levels of IL-1beta, a prothrombotic cytokine, are elevated in unstable angina versus stable angina

BACKGROUND

Multiple studies support a role for inflammation in the pathogenesis of coronary atherosclerosis and unstable cardiac syndromes. However, of the known proinflammatory cytokines, only elevated plasma levels of interleukin-6 have been linked to unstable angina. We sought to examine the plasma levels of other major proinflammatory cytokines in similar clinical settings and to determine the extent of the relationship between inflammation and unstable coronary syndromes by measuring the levels of various proinflammatory cytokines in patients with stable and unstable angina.

METHODS

We measured plasma levels of interleukin-1 beta (IL-1beta), tumor necrosis factor alpha (TNF-alpha), and interleukin 6 (IL-6) in 97 patients: 67 with stable angina, 24 with unstable angina, and 15 healthy controls.

RESULTS

Mean levels of IL-1beta were significantly higher in patients with unstable angina as compared to patients with stable angina (p =.009). Levels of IL-6 were significantly higher than control patients for both stable angina and unstable angina patients (p =.031 and.006, respectively). No significant differences were found in the levels of TNF-alpha.

CONCLUSIONS

Our results suggest that both IL-1beta and IL-6 contribute to the pathogenesis of unstable angina, and that the profile of circulating plasma levels of proinflammatory cytokines differs in unstable angina from that in stable angina. Abbreviated Abstract. Multiple studies support a role for inflammation in the pathogenesis of coronary atherosclerosis and unstable cardiac syndromes. We measured plasma levels of interleukin-1 beta (IL-1beta), tumor necrosis factor alpha (TNF-alpha), and interleukin 6 (IL-6) in patients with stable and unstable coronary syndromes. Levels of IL-1beta and IL-6 were found to be elevated in patients with unstable coronary syndromes. No significant differences were found in the levels of TNF-alpha. Our results suggest that both IL-1beta and IL-6 contribute to the pathogenesis of unstable angina.

Inflammatory profile in unstable angina versus stable angina in patients undergoing percutaneous interventions

BACKGROUND

Inflammatory markers have been shown to be elevated in acute coronary syndromes. Recently, interleukin-6 was demonstrated to be elevated in unstable angina compared with stable angina. However, the effect of percutaneous coronary interventions on the levels of inflammatory markers is less well known.

METHODS AND RESULTS

In this study, we measured the levels of interleukin-6 and interleukin-1 by using enzyme-linked immunosorbent assays in patients with angina pectoris undergoing coronary interventions and in healthy control subjects. Interleukin-6 was significantly elevated in patients with unstable angina compared with patients with stable angina (P= .01). There were no significant differences between the levels of interleukin-1 in patients with unstable angina versus patients with stable angina and healthy control subjects. Furthermore, at 1-month follow-up after percutaneous coronary interventions, there were no longer any significant differences between the levels of interleukin-6 in patients with unstable angina versus patients with stable angina and healthy control subjects.

CONCLUSIONS

These data suggest that interleukin-6 levels may correlate with instability of atheromatous plaques and that the decrease of interleukin-6 levels after percutaneous coronary interventions may represent plaque reendothelialization and stabilization.

Inflow valve regurgitation during left ventricular assist device support may interfere with reverse ventricular remodeling

BACKGROUND

Left ventricular assist devices have been reported previously to reverse ventricular remodeling in patients with dilated cardiomyopathy. In patients with prolonged mechanical support, structural failure of the left ventricular assist device inflow valve can cause regurgitation into the left ventricle, which may affect adversely this process.

METHODS

Left ventricular end-diastolic pressure-volume relation of hearts explanted from 8 patients with left ventricular assist device and 8 control subjects with idiopathic cardiomyopathy was determined ex vivo at the time of transplantation.

RESULTS

Duration of mechanical support ranged from 210 to 276 days (mean +/- standard deviation = 283 +/- 76 days) in 3 patients with inflow valve regurgitation versus 100 to 155 days (132 +/- 22 days) in 5 patients without (p = 0.005). The end-diastolic pressure-volume relation of all hearts supported mechanically was shifted to the left toward normal controls. This effect was markedly attenuated in patients with inflow valve regurgitation.

CONCLUSIONS

Mechanical assistance can cause reverse remodeling in patients with dilated cardiomyopathy as evidenced by the shift in the end-diastolic pressure-volume relation curve to the left. Inflow valve failure, associated with prolonged support, can attenuate changes in left ventricular structure and dimension. Ineffective pressure and volume unloading may explain these observations.

Percutaneous interventions alter the hemostatic profile of patients with unstable versus stable angina

OBJECTIVES

The objectives of this study were to define the hemostatic profiles of patients with unstable angina compared with patients with stable angina and to investigate the effect of percutaneous interventions on the follow-up hemostatic profiles of these patients.

BACKGROUND

Disturbances in hemostatic factors have been shown to be present in various clinical syndromes involving coronary artery disease. However, their role in stable angina versus unstable angina is less well defined.

METHODS

We studied 61 patients with either stable or unstable angina undergoing percutaneous coronary interventions. Blood samples were drawn immediately before the intervention and at 1-month follow-up. Plasma levels of tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1) and von Willebrand factor (vWF) were measured by enzyme-linked immunosorbent assays.

RESULTS

Patients with unstable angina had significantly higher t-PA levels (mean [+/-SE] 23.7 +/- 3.4 vs. 14.3 +/- 1.4 ng/ml, respectively, p = 0.02) and vWF antigen concentrations (2,231 +/- 157 vs. 1,792 +/- 108 mU/ml, respectively, p = 0.03) than patients with stable angina. No statistically significant differences were observed in the PAI-1 levels between the two groups (27.9 +/- 5.5 vs. 21.4 +/- 2.5 ng/ml, respectively, p = 0.25). At 1-month follow-up, there were no longer any significant differences in the t-PA or vWF levels between the two groups (15.7 +/- 1.2 vs. 13.6 +/- 0.6 ng/ml, p = 0.13; 1,962 +/- 170 vs. 1,809 +/- 88 mU/ml, p = 0.39, respectively). There were no significant differences between the hemostatic profiles of patients undergoing percutaneous transluminal coronary angioplasty or coronary stenting initially and at 1-month follow-up.

CONCLUSIONS

These data suggest that elevated plasma levels of t-PA and vWF may correlate with instability of atheromatous plaques, and that their decrease after coronary interventions may reflect plaque reendothelialization and stabilization.

Noonan syndrome associated with neuroblastoma: a case report

We report a case of a child with Noonan phenotype and incidental radiographic findings of mediastinal neuroblastoma. Recent studies have reported an increased association of Noonan syndrome with some malignancies, and the case we present here is the first reported case to our knowledge of an association of neuroblastoma with Noonan syndrome.

Determination of surgeon-generated gown pressures during various surgical procedures in the operating room

BACKGROUND

Patients' blood or other potentially infectious body fluids frequently pass through surgeons' gowns in the operating room. These fluids are absorbed by the scrub suit and can directly contaminate the surgeons' skin. Protective barriers remain an important method of exposure control for many blood-borne pathogens. The efficacy of surgical gowns in preventing this passage or strikethrough has therefore become the focus of much attention. Limited data are available concerning the magnitude and duration of pressure against surgeons' gowns.

METHODS

A 32-sensor mat placed in the abdominal area was used to obtain pressure data for 15 surgeons of both sexes performing 20 procedures.

RESULTS

The percentage of time any pressure was detected varied from 0% during knee reconstruction to 97.4% for excision of a stomach mass. In 16 procedures, more than 87.8% of pressure contacts were 2 N/cm2 (2.9 psi or less); in addition, more than 80% of the contacts were 15 seconds or less during 13 of the procedures. No correlation was found between the amount of pressure and sex of the surgeon, surgical service, or length of the procedure.

CONCLUSIONS

Because pressure is related to the type of procedure, gowns should be chosen to afford protection against fluid strikethrough for the pressures and blood loss anticipated.

Laboratory testing of bolts and screws in cancellous bone

The pull-out resistance of 6.5-mm cancellous screws and 4.0-mm bolts with 12-mm washers from cancellous beef bone was measured. The findings are the following: (1) The 4.0-mm bolt with the 12-mm washer had greater pull-out resistance from thin (12-mm thick) cancellous bone than did the 6.5-mm cancellous screw. (2) In thicker cancellous bone (35 mm), the bolt and washer had greater pull-out resistance than did the screw, but the difference is not significant. (3) There was no significant difference in pull-out resistance of the cancellous screw from holes drilled with a 3.2- or a 4.5-mm bit. These findings support the use of bolts for fixation of thinner sections of cancellous bone, but not when the bolt or screw is in thicker cancellous bone.

Selenium heterocycles XVIII: Synthesis and antibacterial activity of 4-substituted (1,2,3-selenadiazol-5-yl) carbamic acid esters and their sulfur analogs

4-Substituted (1,2,3-selenadiazol-5-yl)carbamic acid esters and their sulfur analogs were prepared from the Curtius rearrangement of the corresponding carboxazides. None of the compounds showed significant antibacterial activity.