Contrast-enhanced CT facilitates rapid, non-destructive assessment of cartilage and bone properties of the human metacarpal.

OBJECTIVE: The aim of this work is to establish the human metacarpal as a new whole joint surface early-stage osteoarthritis (OA) model that enables comparisons of articular cartilage and subchondral bone through high resolution contrast-enhanced CT (CECT) imaging, mechanical testing, and biochemical analysis. DESIGN: The fourth metacarpal was obtained from 12 human cadaveric donors and baseline µCT imaging was followed by indentation testing. The samples were then immersed in anionic (Ioxaglate) and cationic (CA4+) iodinated contrast agent solutions followed by CECT. Cartilage GAG content and distribution was measured using the 1,9 dimethylmethylene blue (DMMB) assay and Safranin-O histology staining. Linear regression was performed to compare cartilage and subchondral bone properties. RESULTS: Strong and significant positive correlations were observed between CA4+ CECT attenuation and both GAG content (R(2) = 0.86) and equilibrium modulus (R(2) = 0.84), while correlations using Ioxaglate were insignificant (R(2) ≤ 0.24, P > 0.05). Subchondral bone plate (SBP) thickness negatively and significantly correlated with SBP mineral density (R(2) = 0.49). Cartilage GAG content significantly correlated with several trabecular bone properties, including positive correlations with bone volume fraction (%BV/TV, R(2) = 0.67), trabecular number (Tb.N, R(2) = 0.60), and trabecular thickness (R(2) = 0.42), and negative relationships with structural model index (SMI, R(2) = 0.78) and trabecular spacing (Tb.Sp, R(2) = 0.56). Similarly, equilibrium modulus correlated positively with %BV/TV (R(2) = 0.50), Tb.N (R(2) = 0.59) and negatively with Tb.Sp (R(2) = 0.55) and SMI (R(2) = 0.60). CONCLUSION: This study establishes the human metacarpal as a new early-stage OA model suitable for rapid, high resolution CECT imaging, mechanical testing, and biochemical analysis of the cartilage and subchondral bone, and for examining their inter-relationships.

Photoactive Electrospun Polymeric Meshes: Spatiotemporally Wetting of Textured 3-Dimensional Structures.

The preparation, characterization, and use of a UV responsive non-woven nanofiber polymeric mesh is reported that transitions from being hydrophobic to hydrophilic. Three distinct wetting profiles are observed during the wetting process. 3D hydrophilic cavities were created within the hydrophobic bulk material by using a photo mask to control the geometry and UV exposure time to control the depth of the region.

Cationic agent contrast-enhanced computed tomography imaging of cartilage correlates with the compressive modulus and coefficient of friction.

OBJECTIVE: The aim of this study is to evaluate whether contrast-enhanced computed tomography (CECT) attenuation, using a cationic contrast agent (CA4+), correlates with the equilibrium compressive modulus (E) and coefficient of friction (µ) of ex vivo bovine articular cartilage. METHODS: Correlations between CECT attenuation and E (Group 1, n = 12) and µ (Group 2, n = 10) were determined using 7 mm diameter bovine osteochondral plugs from the stifle joints of six freshly slaughtered, skeletally mature cows. The equilibrium compressive modulus was measured using a four-step, unconfined, compressive stress-relaxation test, and the coefficients of friction were determined from a torsional friction test. Following mechanical testing, samples were immersed in CA4+, imaged using µCT, rinsed, and analyzed for glycosaminoglycan (GAG) content using the 1,9-dimethylmethylene blue (DMMB) assay. RESULTS: The CECT attenuation was positively correlated with the GAG content of bovine cartilage (R(2) = 0.87, P < 0.0001 for Group 1 and R(2) = 0.74, P = 0.001 for Group 2). Strong and significant positive correlations were observed between E and GAG content (R(2) = 0.90, P < 0.0001) as well as CECT attenuation and E (R(2) = 0.90, P < 0.0001). The CECT attenuation was negatively correlated with the three coefficients of friction: CECT vs µ(static) (R(2) = 0.71, P = 0.002), CECT vs µ(static_equilibrium) (R(2) = 0.79, P < 0.001), and CECT vs µ(kinetic) (R(2) = 0.69, P = 0.003). CONCLUSIONS: CECT with CA4+ is a useful tool for determining the mechanical properties of ex vivo cartilage tissue as the attenuation significantly correlates with the compressive modulus and coefficient of friction.

Using a mailed survey to predict hospital admission among patients older than 80.

OBJECTIVE: To determine if the results of a questionnaire mailed to older patients can help identify those patients at greatest risk of hospital admission. DESIGN: A longitudinal cohort study. SETTING: A prepaid managed care plan in the Denver metropolitan area. PARTICIPANTS: Of the 4414 eligible patients at least 81 years old, 3745 (84.8%) responded. MEASUREMENTS: We studied the predictive power of self-reported demographic, health status, medical history, health habits, functional status (including Katz' activities of daily living and OARS instrumental activities of daily living), and socioeconomic status data to identify those older adults at greatest risk of hospitalization within 4.5 months of completing the survey. We derived our predictive model on one-half the subjects and tested its validity it on the other half. RESULTS: Univariate analysis revealed 25 variables significantly associated with hospital admission. In a logistic regression model, four significant variables successfully stratified the patients by risk of admission. These four variables are: the presence of heart disease, the presence of diabetes, need for help preparing meals, and limited physical independence (requiring the help of a person or mechanical aid to get around). In addition, there was an antagonistic interaction between the presence of heart disease and limited physical independence. The model stratified patients from low risk (4.5% chance of admission) to high risk (39% chance of admission). As measured by the Hosmer-Lemeshow statistic and the area under a receiver-operator characteristic (ROC) curve, this model fit both the derivation and validation subjects well. CONCLUSIONS: A mailed questionnaire achieved a high response rate, and the information collected produced an effective model predictive of hospitalization in the short term. Four easily ascertained pieces of information identify those patients older than age 81 at increased risk.

Isolated central nervous system mucormycosis.

Isolated central nervous system (CNS) mucormycosis is a rare but life-threatening infection. We report a case of bilateral frontal lobe mucormycosis in a previously healthy woman. Intravenous drug use was the most likely route of infection. After treatment with surgical drainage and amphotericin B, she survived but suffered permanent neurologic deficits. We identified 29 previous reports of isolated CNS mucormycosis in the medical literature. Including our case, the patients averaged 32 years of age and most were male. Intravenous drug use appears to be the most important risk factor, present in 20 patients (67%). Treatment with amphotericin B was the only predictor of survival, reducing mortality from 92% to 41%. Isolated CNS mucormycosis should be considered in the differential diagnosis of brain abscesses, especially in intravenous drug users. Prompt initiation of therapy with amphotericin B may be life-saving.

A simple strategy to improve patient adherence to outpatient fecal occult blood testing.

Poor patient adherence reduces the effectiveness of fecal occult blood testing for colon cancer. Patients at the inner-city clinic involved in the study have historically completed only one-third of the tests administered to them. The authors studied three ways of returning test kits (by hand, by mail, and by mail with prepaid postage). Among 146 randomly assigned patients, the completion rates were 37%, 57%, and 71%, respectively. The difference was significant between the first and third groups (p = 0.003), and the cost was less for the third group ($1.71 vs $2.24 per completed test). The authors recommend that clinics serving indigent populations use postage-paid return envelopes with fecal occult blood testing to improve its effectiveness and save money.

Successful treatment of lentigo maligna and lentigo maligna melanoma with Mohs' micrographic surgery aided by rush permanent sections.

BACKGROUND: Lentigo maligna (LM) is a pigmented neoplasm on sun-exposed skin of elderly patients. LM slowly increases in size and may become lentigo maligna melanoma (LMM), a potentially fatal malignancy. Complete excision is the treatment of choice. Mohs' micrographic surgery (MMS) with frozen and permanent sections may be used for complete eradication of the lesion, while sparing as much normal tissue as possible. The authors studied the efficacy of MMS for the treatment of LM and LMM. METHODS: Between 1985 and 1992, 45 patients with LM (26) and LMM (19) were treated with MMS. The authors' technique was to use examination of frozen sections and rush permanent sections (prepared and read within 24 hours). Positive frozen sections warranted further excision. For negative or equivocal frozen sections, surgery was interrupted until the examination of permanent sections was performed. RESULTS: All 45 patients were free of local disease and evidence of metastases at an average of 29.2 months (range, 4-81 months) after therapy. CONCLUSIONS: MMS aided by rush permanent sections yielded a prolonged disease free survival for all 45 patients with LM or LMM. Because the MMS technique minimizes the removal of normal tissue, and the local cure rate in this study was superior to that reported for conventional surgery, the authors recommend this technique for the treatment of LM and LMM.