Monitoring of freezing patterns within 3D collagen-hydroxyapatite scaffolds using infrared thermography.

The importance of cryopreservation in tissue engineering is unceasingly increasing. Preparation, cryopreservation, and storage of tissue-engineered constructs (TECs) at an on-site location offer a convenient way for their clinical application and commercialization. Partial freezing initiated at high sub-zero temperatures using ice-nucleating agents (INAs) has recently been applied in organ cryopreservation. It is anticipated that this freezing technique may be efficient for the preservation of both scaffold mechanical properties and cell viability of TECs. Infrared thermography is an instrumental method to monitor INAs-mediated freezing of various biological entities. In this paper, porous collagen-hydroxyapatite (collagen-HAP) scaffolds were fabricated and characterized as model TECs, whereas infrared thermography was proposed as a method for monitoring the crystallization-related events on their partial freezing down to -25 °C. Intra- and interscaffold latent heat transmission were descriptively evaluated. Nucleation, freezing points as well as the degree of supercooling and duration of crystallization were calculated based on inspection of respective thermographic curves. Special consideration was given to the cryoprotective agent (CPA) composition (Snomax®, crude leaf homogenate (CLH) from Hippophae rhamnoides, dimethyl sulfoxide (Me2SO) and recombinant type-III antifreeze protein (AFP)) and freezing conditions ('in air' or 'in bulk CPA'). For CPAs without ice nucleation activity, thermographic measurements demonstrated that the supercooling was significantly milder in the case of scaffolds present in a CPA solution compared to that without them. This parameter (ΔT, °C) altered with the following tendency: 10 Me2SO (2.90 ± 0.54 ('scaffold in a bulk CPA') vs. 7.71 ± 0.43 ('bulk CPA', P < 0.0001)) and recombinant type-III AFP, 0.5 mg/ml (2.65 ± 0.59 ('scaffold in a bulk CPA') vs. 7.68 ± 0.34 ('bulk CPA', P < 0.0001)). At the same time, in CPA solutions with ice nucleation activity the least degree of supercooling and the longest crystallization duration (Δt, min) for scaffolds frozen 'in air' were documented for CLH from Hippophae rhamnoides (1.57 ± 0.37 °C and 21.86 ± 2.93 min) compared to Snomax, 5 µg/ml (2.14 ± 0.33 °C and 19.91 ± 4.72 min), respectively). Moreover, when frozen 'in air' in CLH from Hippophae rhamnoides, collagen-HAP scaffolds were shown to have the longest ice-liquid equilibrium phase during crystallization and the lowest degree of supercooling followed by alginate core-shell capsules and nanofibrous electrospun fiber mats made of poly ɛ-caprolactone (PCL) and polylactic acid (PLA) (PCL/PLA) blend. The paper offers evidence that infrared thermography provides insightful information for monitoring partial freezing events in TECs when using different freezing containers, CPAs and conditions. This may further TEC-specific cryopreservation with enhanced batch homogeneity and optimization of CPA compositions of natural origin active at warm sub-zero temperatures.

Health-related quality of life in patients with class II and class III obesity.

BACKGROUND: Severe obesity may substantially impact quality of life. We estimated the health-related quality of life (HRQoL) in patients with class II and class III obesity, and explored the impact of patient characteristics and co-morbidities on quality of life. METHODS: 110 patients with BMI > or = 35 kg/m2 presenting for evaluation for bariatric surgery were asked to complete the EuroQoL questionnaire. Co-morbidities of the patients were recorded, including coxarthralgia, gonarthralgia, foot problems (pain and arthrosis), diabetes, dyslipidemia, hypertension, infertility, coronary heart disease, low back pain, peptic esophagitis, sleep apnea syndrome, urinary stress incontinence, and venous insufficiency. The determinants of HRQoL on the EQ-VAS score and EQ-5D index (both ranging from 0-100) were analyzed in a univariate and multivariate linear regression model. RESULTS: The mean EQ-5D index (societal perspective) was 76, whereas the mean EQ-VAS (patient perspective) was 66 (P<0.0001). The mean number of comorbidities was 4.9 (range 0-11). Dyslipidemia (68%), low back pain (63%) and venous insufficiency (57%) were the 3 most frequent co-morbidities. However, low back pain (beta= -11.4) and foot problems (beta= -8.5) were significantly associated with a reduction in the EQ-VAS score, whereas low back pain (beta= -8.4) and coronary heart disease (beta= -24.9) were significantly associated with a reduction in the EQ-5D index. CONCLUSION: The number and type of co-morbidities determine HRQoL in patients with severe obesity. Within our study population, a higher BMI, however, was not associated with a lower quality of life.

Impact of age, sex and body mass index on outcomes at four years after gastric banding.

BACKGROUND: Adjustable gastric banding for weight reduction in severely obese persons allows reversible individualized restriction during postoperative follow-up. It is unknown whether preoperative age, sex and BMI might modulate treatment outcome. METHODS: 404 severely obese patients (79% women; age 42 +/- 0.5 years [mean +/- SEM]; BMI 42.1 +/- 0.2 kg/m2) completed 4-year follow-up after banding. Weight loss, complications, and Bariatric Analysis and Reporting Outcome System (BAROS) scores were recorded prospectively. RESULTS: 4 years after banding, younger (<50 years) women lost more weight than older (50 years) men (28.2 +/- 0.7% vs 19.4+/- 1.6%; P=0.001); older women and younger men lost similar weight. Patients with preoperative BMI >50 lost more weight than patients with BMI <35 (30.5 +/- 2.3% vs 22.8 +/- 2.6%; P=0.03). 22.3% of patients (n=90) had band system-related complications. Compared to women, men had more band leaks (7.0% vs 1.9%; P=0.007), and older men had more band slippages than younger men (8.4% vs 0.0%; P=0.035). Patients with preoperative BMI >50 were less likely than patients with BMI 35-40 or 40-50 to experience gastric complications (10.6%, 18.8%, 23.0%, respectively), but more likely to experience port/tube complications (15.8%, 2.4%, 7.9%, respectively; P<0.055). BAROS scores were different between men and women (P=0.05), and between younger and older people (P=0.001). Women and younger people were more likely than men and older people to score "very good" (P=0.03, P=0.001, respectively). CONCLUSIONS: Adjustable gastric banding is an effective intermediate-term treatment for severe obesity. Preoperative age, sex, and BMI are important modulators of outcome and should be considered during preoperative evaluation.