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The remarkable three-dimensional network structure of bacterial cellulose for tissue engineering applications

Halib N, Ahmad I, Grassi M, Grassi G

Int J Pharm, 2019 Jul 20;566:631-640.
PMID: 31195074 DOI: 10.1016/j.ijpharm.2019.06.017

Cellulose is a natural homopolymer, composed of β-1,4- anhydro-d-glucopyranose units. Unlike plant cellulose, bacterial cellulose (BC), obtained from species belonging to the genera of Acetobacter, Rhizobium, Agrobacterium, and Sarcina through various cultivation methods and techniques, is produced in its pure form. BC is produced in the form of gel-like, never dry sheet with tremendous mechanical properties. Containing up to 99% of water, BC hydrogel is considered biocompatible thus finding robust applications in the health industry. Moreover, BC three-dimensional structure closely resembles the extracellular matrix (ECM) of living tissue. In this review, we focus on the porous BC morphology particularly suited to host oxygen and nutrients thus providing conducive environment for cell growth and proliferation. The remarkable BC porous morphology makes this biological material a promising templet for the generation of 3D tissue culture and possibly for tissue-engineered scaffolds.
Topological characterization of a bacterial cellulose-acrylic acid polymeric matrix

Halib N, Mohd Amin MC, Ahmad I, Abrami M, Fiorentino S, Farra R, et al.

Eur J Pharm Sci, 2014 Oct 1;62:326-33.
PMID: 24932712 DOI: 10.1016/j.ejps.2014.06.004

This paper focuses on the micro- and nano-topological organization of a hydrogel, constituted by a mixture of bacterial cellulose and acrylic acid, and intended for biomedical applications. The presence of acrylic acid promotes the formation of two interpenetrated continuous phases: the primary "pores phase" (PP) containing only water and the secondary "polymeric network phase" (PNP) constituted by the polymeric network swollen by the water. Low field Nuclear Magnetic Resonance (LF NMR), rheology, Scanning Electron Microscopy (SEM) and release tests were used to determine the characteristics of the two phases. In particular, we found that this system is a strong hydrogel constituted by 81% (v/v) of PP phase the remaining part being occupied by the PNP phase. Pores diameters span in the range 10-100 μm, the majority of them (85%) falling in the range 30-90 μm. The high PP phase tortuosity indicates that big pores are not directly connected to each other, but their connection is realized by a series of interconnected small pores that rend the drug path tortuous. The PNP is characterized by a polymer volume fraction around 0.73 while mesh size is around 3 nm. The theoretical interpretation of the experimental data coming from the techniques panel adopted, yielded to the micro- and nano-organization of our hydrogel.
Antibacterial drug release from a biphasic gel system: Mathematical modelling

Abrami M, Golob S, Pontelli F, Chiarappa G, Grassi G, Perissutti B, et al.

Int J Pharm, 2019 Mar 25;559:373-381.
PMID: 30716402 DOI: 10.1016/j.ijpharm.2019.01.055

Bacterial infections represent an important drawback in the orthopaedic field, as they can develop either immediately after surgery procedures or after some years. Specifically, in case of implants, they are alleged to be troublesome as their elimination often compels a surgical removal of the infected implant. A possible solution strategy could involve a local coating of the implant by an antibacterial system, which requires to be easily applicable, biocompatible and able to provide the desired release kinetics for the selected antibacterial drug. Thus, this work focusses on a biphasic system made up by a thermo-reversible gel matrix (Poloxamer 407/water system) hosting a dispersed phase (PLGA micro-particles), containing a model antibacterial drug (vancomycin hydrochloride). In order to understand the key parameters ruling the performance of this delivery system, we developed a mathematical model able to discriminate the drug diffusion inside micro-particles and within the gel phase, eventually providing to predict the drug release kinetics. The model reliability was confirmed by fitting to experimental data, proposing as a powerful theoretical approach to design and optimize such in situ delivery systems.
Mind the gap: reconciling tropical forest carbon flux estimates from earth observation and national reporting requires transparency

Heinrich V, House J, Gibbs DA, Harris N, Herold M, Grassi G, et al.

Carbon Balance Manag, 2023 Nov 20;18(1):22.
PMID: 37982938 DOI: 10.1186/s13021-023-00240-2

BACKGROUND: The application of different approaches calculating the anthropogenic carbon net flux from land, leads to estimates that vary considerably. One reason for these variations is the extent to which approaches consider forest land to be "managed" by humans, and thus contributing to the net anthropogenic flux. Global Earth Observation (EO) datasets characterising spatio-temporal changes in land cover and carbon stocks provide an independent and consistent approach to estimate forest carbon fluxes. These can be compared against results reported in National Greenhouse Gas Inventories (NGHGIs) to support accurate and timely measuring, reporting and verification (MRV). Using Brazil as a primary case study, with additional analysis in Indonesia and Malaysia, we compare a Global EO-based dataset of forest carbon fluxes to results reported in NGHGIs.
RESULTS: Between 2001 and 2020, the EO-derived estimates of all forest-related emissions and removals indicate that Brazil was a net sink of carbon (- 0.2 GtCO2yr-1), while Brazil's NGHGI reported a net carbon source (+ 0.8 GtCO2yr-1). After adjusting the EO estimate to use the Brazilian NGHGI definition of managed forest and other assumptions used in the inventory's methodology, the EO net flux became a source of + 0.6 GtCO2yr-1, comparable to the NGHGI. Remaining discrepancies are due largely to differing carbon removal factors and forest types applied in the two datasets. In Indonesia, the EO and NGHGI net flux estimates were similar (+ 0.6 GtCO2 yr-1), but in Malaysia, they differed in both magnitude and sign (NGHGI: -0.2 GtCO2 yr-1; Global EO: + 0.2 GtCO2 yr-1). Spatially explicit datasets on forest types were not publicly available for analysis from either NGHGI, limiting the possibility of detailed adjustments.
CONCLUSIONS: By adjusting the EO dataset to improve comparability with carbon fluxes estimated for managed forests in the Brazilian NGHGI, initially diverging estimates were largely reconciled and remaining differences can be explained. Despite limited spatial data available for Indonesia and Malaysia, our comparison indicated specific aspects where differing approaches may explain divergence, including uncertainties and inaccuracies. Our study highlights the importance of enhanced transparency, as set out by the Paris Agreement, to enable alignment between different approaches for independent measuring and verification.
Fulltext Roadmap for the Management of Type 2 Diabetes and Hypertension in the Middle East: Review of the 2022 EVIDENT Summit

Al Saleh Y, Al Busaidi N, Al Dahi W, Almajnoni M, Mohammed AS, Alshali K, et al.

Adv Ther, 2023 Jul;40(7):2965-2984.
PMID: 37233878 DOI: 10.1007/s12325-023-02529-7

Type 2 diabetes mellitus (T2DM) and hypertension are leading risk factors for death and disability in the Middle East. Both conditions are highly prevalent, underdiagnosed and poorly controlled, highlighting an urgent need for a roadmap to overcome the barriers to optimal glycaemic and blood pressure management in this region. This review provides a summary of the Evidence in Diabetes and Hypertension Summit (EVIDENT) held in September 2022, which discussed current treatment guidelines, unmet clinical needs and strategies to improve treatment outcomes for patients with T2DM and hypertension in the Middle East. Current clinical guidelines recommend strict glycaemic and blood pressure targets, presenting several treatment options to achieve and maintain these targets and prevent complications. However, treatment targets are infrequently met in the Middle East, largely due to high clinical inertia among physicians and low medication adherence among patients. To address these challenges, clinical guidelines now provide individualised therapy recommendations based on drug profiles, patient preferences and management priorities. Efforts to improve the early detection of prediabetes, T2DM screening and intensive, early glucose control will minimise long-term complications. Physicians can use the T2DM Oral Agents Fact Checking programme to help navigate the wide range of treatment options and guide clinical decision-making. Sulfonylurea agents have been used successfully to manage T2DM; a newer agent, gliclazide MR (modified release formulation), has the advantages of a lower incidence of hypoglycaemia with no risk of cardiovascular events, weight neutrality and proven renal benefits. For patients with hypertension, single-pill combinations have been developed to improve efficacy and reduce treatment burden. In conjunction with pragmatic treatment algorithms and personalised therapies, greater investments in disease prevention, public awareness, training of healthcare providers, patient education, government policies and research are needed to improve the quality of care of patients with T2DM and/or hypertension in the Middle East.