A model to determine at-home restrictions for cats after treatment of hyperthyroidism with radioiodine.

OBJECTIVES: Felinehyperthyroidism is the most common endocrine disease of older cats and radioiodine is considered to be the gold standard treatment. Isolation periods following treatment vary depending on both individual treatment facilities and the relevant legislation of the country; therefore, there is no recognised standardised protocol defining the length of isolation. This work describes how our institution validated that its owner restrictions met dose constraints by using a model of iodine retention to calculate the required duration and nature of owner restrictions. MATERIALS AND METHODS: The retained radioactivity of cats at the point of discharge was used to simulate the radiation dose to owners in the 90 days following release. The model created was used to calculate the minimum duration of isolation for a range of administered activities and owner restrictions. RESULTS: Using the model, it was found that when injected with the maximum dose used, 222 MBq radioiodine, it was possible to release cats after 14 days of isolation and keep owner doses below 0.30 mSv (whole-body effective dose constraint for a single radiation source) with some restrictions. It was possible to release after 23 days with no restrictions. CLINICAL SIGNIFICANCE: The present study provides clinicians with a consistent and verified method in which they can calculate the isolation periods for radioiodine-treated cats.

Cumulative psychosocial risks, internal asse, and past 30-day tobacco use among middle and high school students: The promise of internal assets.

INTRODUCTION: Research has demonstrated a robust relationship between psychosocial risk factors (e.g., perceptions of health risk, peer and parent influences, and school climate) and adolescent tobacco use. However, whether internal assets (IAs), factors that promote healthy youth development, can mitigate the adverse effects of psychosocial risks on tobacco use has not been well researched. METHOD: Using a population-based sample of middle and high school students (N = 112,364), multilevel logistic and negative binomial regression models estimated the direct effects of cumulative psychosocial risks and IAs on student tobacco use (e.g., combustible, non-combustible, alternative delivery systems) and assessed whether IAs moderated the relationship between psychosocial risks and tobacco use. RESULTS: Results indicate that every additional psychosocial risk factor was associated with an estimated 100% (AOR: 2.04, 95% CI: 1.88-2.22) to 57% (AOR: 1.57, 95% CI: 1.52-1.62) increase in the odds of using tobacco and a 60% increase in the estimated number of products used. IAs were inversely associated with tobacco use and attenuated the association between cumulative psychosocial risks and use. Among students experiencing all five psychosocial risks, boys had an estimated 20% reduction, and girls an estimated 50% reduction, in the probability of tobacco use at the highest mean scores of IAs. CONCLUSION: Universal, school-based prevention programs will benefit from identifying and targeting a set of shared risk and protective factors for tobacco use. Bolstering resilience by facilitating students' IAs represents a promising direction for youth focused prevention efforts.

Recovery after PILP remineralization of dentin lesions created with two cariogenic acids.

OBJECTIVES: Acetate and lactate are important cariogenic acids produced by oral bacteria. They produced different residual dentin structures in artificial lesions of similar depth. We evaluated if such lesions responded in the same way to a polymer-induced-liquid-precursor (PILP) remineralization. DESIGN: Dentin blocks obtained from human third molars, divided into 6 groups (n=3). Blocks were demineralized with acetate (66h) or lactate (168h) buffer at pH 5.0 to create 140µm target lesion depths. A-DEM and L-DEM groups received no remineralization. Other groups were remineralized for 14days. 100µg/mL polyaspartate was added into the remineralizing buffer for A-PIL and L-PIL, whereas A-CAP and L-CAP were treated with the same solution but without polyaspartate. Cross-sectioned blocks were examined for shrinkage and AFM-topography. Line profiles of reduced elastic modulus (Er) were obtained by AFM-based nanoindentation across the lesion. Ultrastructures were examined with TEM. RESULTS: A-PIL and L-PIL recovered in shrinkage to the original height of the dentin and it appeared normal with tubules, with increases in Er at both outer flat and inner sloped zones. At the sloped zone, acetate lesions lost more Er but recovery rate after PILP was not statistically different from lactate lesions. A-CAP and L-CAP showed surface precipitates, significantly less recovery in shrinkage or Er as compared to PILP groups. TEM-ultrastructure of PILP groups showed similar structural and mineral components in the sloped zone for lesions produced by either acid. CONCLUSIONS: The PILP process provided significant recovery of both structure and mechanical properties for artificial lesions produced with acetate or lactate.

Repair of dentin defects from DSPP knockout mice by PILP mineralization.

Dentinogenesis imperfecta type II (DGI-II) lacks intrafibrillar mineral with severe compromise of dentin mechanical properties. A Dspp knockout (Dspp-/-) mouse, with a phenotype similar to that of human DGI-II, was used to determine if poly-L-aspartic acid [poly(ASP)] in the "polymer-induced liquid-precursor" (PILP) system can restore its mechanical properties. Dentin from six-week old Dspp-/- and wild-type mice was treated with CaP solution containing poly(ASP) for up to 14 days. Elastic modulus and hardness before and after treatment were correlated with mineralization from Micro x-ray computed tomography (Micro-XCT). Transmission electron microscopy (TEM)/Selected area electron diffraction (SAED) were used to compare matrix mineralization and crystallography. Mechanical properties of the Dspp-/- dentin were significantly less than wild-type dentin and recovered significantly (P < 0.05) after PILP-treatment, reaching values comparable to wild-type dentin. Micro-XCT showed mineral recovery similar to wild-type dentin after PILP-treatment. TEM/SAED showed repair of patchy mineralization and complete mineralization of defective dentin. This approach may lead to new strategies for hard tissue repair.

Chitosan-mediated crystallization and assembly of hydroxyapatite nanoparticles into hybrid nanostructured films.

The synthesis and subsequent assembly of nearly spherical nano-hydroxyapatite (nHA) particles in the presence of trace amounts of the polysaccharide chitosan was carried out employing a wet chemical approach. Chitosan addition during synthesis not only modulated HA crystallization but also aided in the assembly of nHA particles onto itself. Solvent extraction from these suspensions formed iridescent films, of which the bottom few layers were rich in self-assembled nHA particle arrays. The cross-section of these hybrid films revealed compositional and hence structural grading of the two phases and exhibited a unique morphology in which assembled nHA particles gradually gave way to chitosan-rich top layers. Transmission electron microscope and selected area electron diffraction studies suggested that the basal plane of HA had interacted with chitosan, and scanning electron microscope studies of the hybrid films revealed multi-length scale hierarchical architecture composed of HA and chitosan. Phase identification was carried out by X-ray diffraction (XRD) and Rietveld analysis of digitized XRD data showed that the basic apatite structure was preserved, but chitosan inclusion induced subtle changes to the HA unit cell. The refinement of crystallite shape using the Popa method clearly indicated a distinct change in the growth direction of HA crystallites from [001] to [100] with increasing chitosan concentration. The paper also discusses the likelihood of chitosan phosphorylation during synthesis, which we believe to be a pathway, by which chitosan molecules chemically interact with calcium phosphate precursor compounds and orchestrate the crystallization of nHA particles. Additionally, the paper suggests several interesting biomedical applications for graded nHA-chitosan nanostructured films.

Scanning electron microscopic analysis of the mineralization of type I collagen via a polymer-induced liquid-precursor (PILP) process.

We have put forth the hypothesis that collagen is mineralized during bone formation by means of a polymer-induced liquid-precursor (PILP) process, in which a liquid-phase mineral precursor could be drawn into the gaps and grooves of the collagen fibrils by capillary action, and upon solidification, leave the collagenous matrix embedded with nanoscopic crystallites of hydroxyapatite. This hypothesis is based upon our observations of capillarity seen for liquid-phase mineral precursors generated with calcium carbonate. Here, we demonstrate proof-of-concept of this mechanism by mineralizing Cellagen sponges (type I reconstituted bovine collagen) in the presence of a liquid-precursor phase to calcium carbonate. Scanning electron microscopy (SEM) was used to examine the mineralized collagen, which in combination with selective etching studies, revealed the extent to which the mineral phase infiltrated the collagenous matrix. A roughly periodic array of disk-like crystals was found to be embedded within the collagen fibers, demonstrating that the mineral phase spans across the diameter of the fibers. Some of the morphological features of the mineralized fibers in our in vitro model system are similar to those seen in natural bone (albeit of a different mineral phase), lending support to our hypothesis that these non-equilibrium morphologies might be generated by a PILP process. SEM provides a different perspective on the morphology of bone, and has been useful here for examining the extent of mineralization in composite structures generated via the PILP process. However, further investigation is needed to examine the nanostructural arrangement of the crystallites embedded within the collagenous matrix.

Compliance: a comparison of three lens care systems.

Noncompliance is an important health care issue. This report presents results of assessments of three different lens care systems and directly compares compliance with each and the potential impact on patients' safety and comfort. Methods involved trained interviewers, patient demonstrations, a panel of experts, statistical analyses, and an assessment of the clinical significance of patients' noncompliant behaviors. These methods were able to discriminate among the levels of compliance with the lens care systems assessed. The three regimens were comparable regarding steps significant to lens wearing comfort with approximately one-third of all patients noncompliant with at least one of these steps. The same cannot be said regarding safety, however, with the incidence of noncompliance at 55, 84, and 91% for the three regimens. These findings indicate that simplicity alone cannot overcome noncompliance and the design of the system is an important consideration when making recommendations regarding lens care.

Intestinal passage of the PEG end-piece: is it safe?

Two rare but life-threatening complications of percutaneous endoscopic gastrostomy (PEG) are reported: small bowel perforation and obstruction. Both resulted from impaction of the PEG end-piece after separation at skin level. Review of the literature revealed very few complications from intestinal passage of PEG end-pieces. The free intragastric PEG end-piece routinely passes through the gastrointestinal tract in most cases. One of these two cases was drawn from a series of 100 patients with intentional intestinal passage of PEG end-pieces to give a severe complication rate of 1%. A case can be made for routine endoscopic per-oral removal of PEG end-pieces in the elective setting, but this is more costly and not without hazard. Previous laparotomy and/or known adhesions is a relative indication for endoscopic retrieval of the PEG end-piece. Oesophageal disease or intolerance of endoscopy is a relative indication for intestinal passage. Close clinical follow up is recommended to ensure that the PEG end-piece has passed per-rectum. If the PEG end-piece has not passed and is shown in the small bowel on plain X-ray at approximately 3 weeks after separation then lodgement has probably occurred and early operative intervention is warranted.

Morphology of block copolyurethanes: V. The effect of -CH2CH2- vs -CH2- spacers between aromatic rings.

Copolyether-urethane-ureas based on 1,2-ethylene bis(4-phenylisocyanate), polypropylene glycol and ethylene diamine were synthesized by both the standard two-step and a multi-step procedure and their properties compared with analogous copolyurethanes based on methylene bis(4-phenylisocyanate). The infrared and dynamic mechanical properties indicate differences in the packing structure of the hard domains between these two copolymer systems. The infrared data suggest that the introduction of a -CH2CH2- spacer between the two aromatic rings of the diisocyanate results in a coplanar packing in the hard domains for these copolyurethanes.

Compliance and contact lens care: a new assessment method.

We propose a new method for assessing and quantifying compliance with contact lens care regimens. We recommend two separate procedures: one in which trained interviewers examine the actual lens care techniques used by typical, experienced patients and another in which clinicians rate each step in a lens care regimen as to the level of risk to the patient's comfort and safety if noncompliance with that step occurs. When combined, these steps quantify compliance with the regimen under investigation. The method can be used to assess the incidence of compliance with the regimen in question, and to compare compliance across dissimilar care systems. In our investigation, we applied the method to a multi-purpose solution regimen which has been marketed as being simple to use and, therefore, the correct care procedures are more likely to be complied with. However, we found that patient compliance with this regimen was equivalent to that found in an earlier study of an oxidative (hydrogen peroxide) care system, with noncompliance posing significant risks to both safety and comfort. The results indicate that 91% of patients were noncompliant with one or more of the steps in the lens care regimen that were judged to be clinically significant safety risk factors. Factors which posed significant risks to comfort were less likely to induce noncompliance. Only 34% of patients failed to follow one or more of the steps judged to provide clinically significant risks to comfort. The authors conclude that multi-purpose or simplified regimens are not acceptable substitutes for careful patient training and frequent follow-up.

Chorion villus sampling--transcervical or transabdominal?

Chorion villus sampling was performed transcervically on 84 patients and transabdominally on 126 patients. Two of 4 (5%) spontaneous abortions in the transcervical group were complicated by uterine infection. Five (4%) spontaneous abortions in the transabdominal group were uncomplicated by infection. The results support the contention that the transabdominal method may be safer and that the procedure related fetal loss rate is similar to that following amniocentesis.