Synthesis and characterization of polyanhydride for local BCNU delivery carriers

p-Carboxyphenoxy propane (CPP) prepolymer consisting of 4 units and sebacic acid (SA) prepolymer consisting of about 10 units were synthesized by reacting CPP and SA in the presence of excess acetic anhydride, respectively. Polyanhydride, poly(CPP-SA) copolymers were copolymerized by a melt polycondensation process with a mixture of CPP and SA prepolymer. Copolymers of average molecular weight up to 110,000 g/mol were achieved. The crystallinity of poly(CPP-SA) copolymers was decreased by the addition of the CPP homopolymer segment to SA homopolymer. Poly(CPP-SA) copolymers gradually degraded for period of 10 days. No large difference of weight loss observed according to molecular weight variation of poly(CPP-SA) copolymers. BCNU release from wafers fabricated by poly(CPP-SA) showed a sustained release pattern with no initial burst and delay of drug release.     

Gradual potentiation of isometric muscle force during constant electrical stimulation

An investigation was carried out into how stimulation frequency and stimulation history affect the potentiation of muscle force during 20s of constant stimulation of the two knee extensors in isometric conditions. Stimulation frequency significantly affected the potentiation pattern: low-frequency (2.5–10 Hz) stimulation showed a reduction and subsequent enhancement of force, and high-frequency (14.3–25 Hz) stimulation showed only enhancement of force. The degree of enhancement in force and time-to-peak decreased with the stimulation frequency. Whereas conditioning stimulation (both 40 Hz and 14.3 Hz) significantly enhanced the muscle force above 85%, following main stimulation (14.3 Hz) after short rest (10 s and 50 s, respectively) induced little force enhancement (below 8%). In particular, when the frequency of the conditioning stimulation was 14.3 Hz, the initial force at the main stimulation showed a very similar value to the final force value of the conditioning stimulation (above 90% similarity). The potentiated twitch force slowly decayed during rest, with an average time constant of 2.4 min. These observations indicate that muscle potentiation depends on the stimulation frequency and stimulation history, and therefore a computer model of potentiation can play an important role in predicting muscle force and body movement induced by electrical stimulation.     

Invasive cutaneous squamous cell carcinoma incidence in US health care workers

Little data on cutaneous squamous cell carcinoma (SCC) epidemiology within the United States are currently available. Prior studies have focused on populations outside of the United States or been limited to regions within the US. In this study, prospective data were collected via biennial questionnaires from a total of 261,609 participants, which included women in the Nurses’ Health Study (NHS, 1976–2008) and Nurses’ Health Study II (NHS II, 1989–2009), and men in the Health Professionals Follow-Up Study (HPFS, 1986–2008). History of physician-diagnosed invasive SCC was confirmed by pathology record review. Over the entire follow-up period for each cohort, there were 1,265 invasive SCC cases per 100,000 persons in the NHS cohort, 389 cases per 100,000 persons in NHS II, and 2,154 cases per 100,000 persons in HPFS. An 18-year follow-up of participants in these cohorts revealed increasing invasive SCC incidence rates over time, with rates for men being consistently higher than those for women. In women, a larger proportion of invasive SCC lesions occurred on the lower extremities as compared to men (21 % in NHS vs. 6 % in HPFS, p < 0.0001; 14 % in NHS II vs. 6 % in HPFS, p < 0.0001), while in men, a larger proportion occurred on the head/neck (43 % in NHS vs. 60 % in HPFS, p < 0.0001; 48 % in NHS II vs. 60 % in HPFS, p < 0.0001). In summary, invasive SCC incidence rates among US men have been greater than those for women with distinct sites of common occurrence between men and women.     

Biological evaluation of intervertebral disc cells in different formulations of gellan gum‐based hydrogels

Gellan gum (GG)‐based hydrogels are advantageous in tissue engineering not only due to their ability to retain large quantities of water and provide a similar environment to that of natural extracellular matrix (ECM), but also because they can gelify in situ in seconds. Their mechanical properties can be fine‐tuned to mimic natural tissues such as the nucleus pulposus (NP). This study produced different formulations of GG hydrogels by mixing varying amounts of methacrylated (GG‐MA) and high‐acyl gellan gums (HA‐GG) for applications as acellular and cellular NP substitutes. The hydrogels were physicochemically characterized by dynamic mechanical analysis. Degradation and swelling abilities were assessed by soaking in a phosphate buffered saline solution for up to 170 h. Results showed that as HA‐GG content increased, the modulus of the hydrogels decreased. Moreover, increases in HA‐GG content induced greater weight loss in the GG‐MA/HA‐GG formulation compared to GG‐MA hydrogel. Potential cytotoxicity of the hydrogel was assessed by culturing rabbit NP cells up to 7 days. An MTS assay was performed by seeding rabbit NP cells onto the surface of 3D hydrogel disc formulations. Viability of rabbit NP cells encapsulated within the different hydrogel formulations was also evaluated by Calcein‐AM and ATP assays. Results showed that tunable GG‐MA/HA‐GG hydrogels were non‐cytotoxic and supported viability of rabbit NP cells. Copyright © 2012 John Wiley & Sons, Ltd.     

The potential of DBP gels containing intervertebral disc cells for annulus fibrosus supplementation:in vivo

Demineralized bone particle (DBP), which is widely used as a biomaterial in the field of tissue engineering, contains various bioactive molecules, such as cytokines. For this reason, in this study we investigated the effects of injectable DBP gels on cell proliferation, inflammation and maintenance of the shape of DBP gels as a scaffold able to substitute for intervertebral discs (IVDs) in vivo. DBP gels were fabricated with different percentages (5% and 10%) of DBP powder and 3% acetic acid, including 0.02% pepsin. DBP gels with 1 × 10⁶ annulus fibrosus (AF) cells were implanted into the dorsal subcutaneous region of BALB/C‐nu mice for 1, 2 and 3 weeks. Cell proliferation was measured by MTT assay. The effect of DBP gels on the inflammatory response was analysed by measuring the amount of tumour necrosis factor‐alpha (TNFα) released. Also, histological methods were carried out to analyse the response of DBP gels in vivo. This study demonstrated that injectable DBP gels are able to provide physical scaffolds for growing IVD cells in vivo. Copyright © 2013 John Wiley & Sons, Ltd.     

Factors predicting therapeutic efficacy of combination treatment with sitagliptin and metformin in type 2 diabetic patients: the COSMETIC study

Objective We assessed the predictive parameters for therapeutic efficacy of initial combination therapy with sitagliptin and metformin in drug‐naïve type 2 diabetic patients. Design, Patients, and Measurements In this 52‐week treatment study, 150 patients (mean age, 54·9 ± 12·5 years) with type 2 diabetes and HbA1c of 7·0–10% were treated with sitagliptin 100 mg once and metformin 500 mg twice daily. To assess the predictive parameters for therapeutic efficacy, a multivariate regression analysis was performed with baseline fasting glucose, insulin, C‐peptide, and glucagon levels, homoeostasis model assessment‐insulin resistance (HOMA‐IR) and β‐cell function (HOMA‐B), insulinogenic index (IGI, defined as 30–0 min insulin/30–0 min glucose), and area under the curve for glucose, insulin, and C‐peptide obtained after 75‐g oral glucose tolerance test. Results After 52 weeks, mean HbA1c levels and fasting and postload 2‐h glucose were significantly decreased from 8·7 ± 1·4% to 7·2 ± 1·3%, 9·2 ± 3·0 to 7·2 ± 1·8 mm , and 17·5 ± 5·1 to 10·9 ± 3·6 mm , respectively (P < 0·01). HOMA‐B and IGI increased significantly from 50·3 ± 33·5 to 75·1 ± 32·8 and from 11·3 ± 1·3 to 35·0 ± 6·3 at 52 weeks, respectively (P < 0·01). Multivariate regression analysis indicated that the reduction in HbA1c was significantly associated with high baseline HbA1c, low IGI, and short duration of diabetes after adjusting for age, sex, body mass index, blood pressure, triglycerides, creatinine, high‐sensitivity CRP, glucagon, C‐peptide, HOMA‐B, and HOMA‐IR. No severe adverse events were observed. Conclusion These results suggest that drug‐naïve type 2 diabetic patients with low β‐cell function would benefit the most from early initial combination therapy of sitagliptin and metformin.