Development of catalyst complexes for upgrading biomass into ester-based biolubricants for automotive applications: a review

Biomass-derived oils are recognised as the most promising renewable resources for the production of ester-based biolubricants due to their biodegradable, non-toxic and metal adhering properties. Homogeneous acid catalysts have been conventionally used in catalytic esterification and transesterification for the synthesis of ester-based biolubricants. Although homogeneous acid catalysts encounter difficulty during phase separation, they exhibit superior selectivity and good stereochemistry and regiochemistry control in the reaction. Consequently, transition metal complex catalysts (also known as homogeneous organometallic catalysts) are proposed for biolubricant synthesis in order to achieve a higher selectivity and conversion. Herein, the potential of both homogeneous transition metal complexes and heterogeneous supported metal complexes towards the synthesis of biolubricants, particularly, in esterification and transesterification, as well as the upgrading process, including hydrogenation and in situ hydrogenation–esterification, is critically reviewed.

The graphical abstract reflects the content of the entire paper; catalyst complexes for upgrading biomass to ester-based biolubricants.     

Mid-diastolic mitral annular motion: a useful marker in the evaluation of left ventricular relaxation and end-diastolic pressure

Various patterns of mid-diastolic mitral annular motion may imply different left ventricular (LV) diastolic function and filling pressure. To be a reliable marker in the evaluation of LV diastolic function and filling pressure, these findings must be validated by invasive method. Hence, this study was designed to compare the LV diastolic properties among different patterns of mid-diastolic mitral annular motion by invasive method. Fifty-five patients undergoing elective cardiac catheterization were included. Study subjects were classified into three groups according to mid-diastolic mitral annular motion patterns. Upward and downward La waves were respectively defined as a clear apically- and atrially-directed mid-diastolic annular motion on at least three consecutive beats with the average peak velocity >or=2 cm/s. Subjects with upward La wave, with downward but without upward La wave, and without La wave were categorized as groups 1, 2 and 3, respectively. The time constant of isovolumic LV pressure decline (tau) and LV end-diastolic pressure (LVEDP) were obtained from a micromanometer-tipped catheter. The tau was shorter and LVEDP was lower in group 1 than in groups 2 and 3 (p < 0.047) but these parameters were comparable between groups 2 and 3. In conclusion, patients with upward La wave had better LV relaxation function and lower LVEDP than patients without it. However, these diastolic properties were comparable between patients with only downward La wave and those without La wave. Therefore, mid-diastolic mitral annular motion is a useful and promising marker in the evaluation of LV relaxation and LVEDP.     

Association between fasting plasma glucose and left ventricular mass and left ventricular hypertrophy over 4 years in a healthy population aged 60 and older

OBJECTIVES: To test the association between fasting glucose level and left ventricular mass (LVM) and left ventricular hypertrophy (LVH) in people aged 60 and older. DESIGN: Population-based prospective study with 4-year follow-up. SETTING: Department of Internal Medicine and Family Medicine, Kaohsiung Medical University (KMU), Chung-Ho Memorial Hospital, and Graduate Institute of Medicine and Public Health, KMU. PARTICIPANTS: Of 1,500 people screened, 105 without symptoms or signs of diabetes mellitus, hypertension, or cardiovascular disease were recruited from senior activity centers in Kaohsiung city. MEASUREMENTS: All received two-dimensional echocardiography and fasting glucose examination at baseline and at 2- and 4-year follow-up. LVH was defined as a LVM index (LVMI) greater than 122.4 g/m(2) or 51 g/m(2.7). RESULTS: Age ranged from 60 to 81 (mean 71.7+/-3.9). Baseline glucose ranged from 83 to 118 mg/dL (mean 99.7+/-7.9 mg/dL). LVMI was significantly higher at the 4-year follow-up (97.5+/-24.9 vs 104.5+/-27.5 g/m(2) and 44.2+/-12.1 vs 47.2+/-13.4 g/m(2.7), both P<.01), as was the occurrence of LVH (16% vs 32% and 25% vs 39%, both P<.01). Baseline glucose correlates with 4-year change in LVMI (both P<.02). In the fourth year, baseline glucose was a significant predictor of LVMI (both P<.01) and LVH (P=.03 in g/m(2) definition) using logistic regression analysis. CONCLUSION: Because fasting glucose is an independent predictor for greater LVM and for development of LVH, it should be considered in assessment of cardiac disease and LVM in healthy older people without diabetes mellitus.     

Implications of the World Trade Organization in combating non-communicable diseases

The World Health Organization (WHO) has proposed a number of strategies to combat non-communicable diseases such as cancers, cardiovascular diseases, chronic respiratory diseases and diabetes by targeting the risk factors of tobacco use, harmful use of alcohol and poor diet. A number of the domestic regulatory responses contemplated by WHO and individual countries have the potential to restrict or distort trade, raising the question of whether they are consistent with the obligations imposed on Members of the World Trade Organization (WTO). This article demonstrates that WTO rules do limit Members’ flexibility in implementing public health measures to address these diseases. However, the focus of WTO provisions on preventing discrimination against or between imports and the exceptions incorporated in various WTO agreements leave sufficient scope for Members to design carefully directed measures to achieve genuine public health goals while minimizing negative effects on international trade.     

Synthetic cationic amphiphilic α-helical peptides as antimicrobial agents

Antimicrobial peptides (AMPs) secreted by the innate immune system are prevalent as the effective first-line of defense to overcome recurring microbial invasions. They have been widely accepted as the blueprints for the development of new antimicrobial agents for the treatment of drug resistant infections. However, there is also a growing concern that AMPs with a sequence that is too close to the host organism's AMP may inevitably compromise its own natural defense. In this study, we design a series of synthetic (non-natural) short α-helical AMPs to expand the arsenal of the AMP families and to gain further insights on their antimicrobial activities. These cationic and amphiphilic peptides have a general sequence of (XXYY)(n) (X: hydrophobic residue, Y: cationic residue, and n: the number of repeat units), and are designed to mimic the folding behavior of the naturally-occurring α-helical AMPs. The synthetic α-helical AMPs with 3 repeat units, (FFRR)(3), (LLRR)(3), and (LLKK)(3), are found to be more selective towards microbial cells than rat red blood cells, with minimum inhibitory concentration (MIC) values that are more than 10 times lower than their 50% hemolytic concentrations (HC(50)). They are effective against Gram-positive B. subtilis and yeast C. albicans; and the studies using scanning electron microscopy (SEM) have elucidated that these peptides possess membrane-lytic activities against microbial cells. Furthermore, non-specific immune stimulation assays of a typical peptide shows negligible IFN-α, IFN-γ, and TNF-α inductions in human peripheral blood mononuclear cells, which implies additional safety aspects of the peptide for both systemic and topical use. Therefore, the peptides designed in this study can be promising antimicrobial agents against the frequently-encountered Gram-positive bacteria- or yeast-induced infections.     

Heart Rate Significantly Influences the Relationship between Atrial Fibrillation and Arterial Stiffness

Background. Atrial fibrillation (AF) and vascular disease share several risk factors and the two diseases often coexist. Heart rate (HR) is reported to be a major determinant of arterial stiffness. AF patients often have a transiently or persistently rapid HR. Hence, this study was to assess whether AF was significantly associated with arterial stiffness and HR could significantly influence the relationship between AF and arterial stiffness. Besides, we also determine the main correlates of arterial stiffness in AF patients and see whether HR was correlated with arterial stiffness in these patients.Methods. We included 166 AF and 1336 non-AF patients from subjects arranged for echocardiographic examinations. Arterial stiffness was assessed by brachial-ankle pulse wave velocity (baPWV).Results. Compared to non-AF patients, AF patients had a higher baPWV (p <0.001). In a multivariate model, including covariates of age, sex, blood pressures and so on, the presence of AF was significantly associated with baPWV (β = 0.079, P = 0.001). However, further adjustment for HR made this association disappear (β = 0.005, P = 0.832). In addition to age and systolic blood pressure, increased HR (β = 0.309, p <0.001) was a major determinant of increased baPWV in our AF patients.Conclusions. This study demonstrated the presence of AF was associated with increased baPWV, but this association became insignificant after further adjustment for HR, which suggested HR could significantly influence the relationship between AF and baPWV. Besides, HR was positively correlated with arterial stiffness in our AF patients.     

Monocyte chemoattractant protein 3 as a mediator of fibrosis: Overexpression in systemic sclerosis and the type 1 tight‐skin mouse

Objective

To determine the gene‐expression profile in dermal fibroblasts from type 1 tight‐skin (Tsk1) mice, and to examine the expression and potential fibrotic activity of monocyte chemoattractant protein 3 (MCP‐3) in Tsk1 mouse and human systemic sclerosis (SSc) skin.

Methods

Complementary DNA microarrays (Atlas 1.2) were used to compare Tsk1 fibroblasts with non‐Tsk1 littermate cells at 10 days, 6 weeks, and 12 weeks of age. Expression of MCP‐3 protein was assessed by Western blotting of fibroblast culture supernatants, and localized in the mouse and human skin biopsy samples by immunohistochemistry. Activation of collagen reporter genes by MCP‐3 was explored in transgenic mouse fibroblasts and by transient transfection assays.

Results

MCP‐3 was highly overexpressed by neonatal Tsk1 fibroblasts and by fibroblasts cultured from the lesional skin of patients with early‐stage diffuse cutaneous SSc. Immunolocalization confirmed increased expression of MCP‐3 in the dermis of 4 of 5 Tsk1 skin samples and 14 of 28 lesional SSc skin samples, compared with that in matched healthy mice (n = 5) and human controls (n = 11). Proα2(I) collagen promoter–reporter gene constructs were activated by MCP‐3 in transgenic mice and by transient transfection assays. This response was maximal between 16 and 24 hours of culture and mediated via sequences within the proximal promoter. The effects of MCP‐3 could be diminished by a neutralizing antibody to transforming growth factor β.

Conclusion

We demonstrate, for the first time, overexpression of MCP‐3 in early‐stage SSc and in Tsk1 skin, and suggest a novel role for this protein as a fibrotic mediator activating extracellular matrix gene expression in addition to promoting leukocyte trafficking. This chemokine may be an important early member of the cytokine cascade driving the pathogenesis of SSc.