Comparative life-cycle impact assessment of concrete manufacturing in Singapore

Purpose

For countries like Singapore that is highly dependent on imported goods, it is essential to consider the consequences of consumption of imported cement and other concrete constituents for a fair carbon trading at global and regional levels. Recently, as a result of reduction in trade barriers and costs of materials and fuels, Singapore does not have much incentive in reducing environmental impacts of these imported goods. However, Singapore has set high environmental targets nationally to reduce impacts from building and construction. In addition to its national efforts, Singapore also needs to take action in trade-related consequences of importing energy-intensive products like cement and aggregates to Singapore. The purpose of this study is to quantify and suggest alternatives for reducing the embodied energy and life-cycle impacts of concrete consumption in Singapore on the basis of current trading volumes of these materials from Singapore’s importers.

Methods

A detailed life-cycle assessment of concrete manufacturing in Singapore is performed to suggest possible ways to reduce the environmental impacts from importing cement and aggregates from Singapore’s trade partners based on an earlier life-cycle inventory developed for Singapore and its neighboring countries. Life-cycle impact assessment (LCIA) impact characterization factors are based on a midpoint-oriented and hierarchist approach as defined by ReCiPe method. Following the LCIA, a scenario analysis is conducted to select the best combination of cement and aggregate importers of Singapore based on their environmental performance.

Results and discussion

Results from the scenario analysis show that overall impacts can be reduced by importing the materials from a nearer source with efficient production technologies and greener fuel mixes. About 10–34 % reduction is estimated in embodied energy, acidification, eutrophication, global warming potential, smog, and health impacts by importing from a closer and technologically greener source.

Conclusions

Despite the limitations due to data and modeling uncertainties, this study constitutes a baseline/benchmark for addressing the current cement and aggregate markets and associated environmental impacts of concrete consumption in Singapore based on historical import quantities of cement and aggregates from neighboring countries of Singapore. In the near future, policy-related action would be influential in achieving Singapore’s national and global environmental targets in buildings and construction sector. Incorporation of an LCA approach into Green Mark Scheme (GMS) by the Building and Construction Authority (BCA) is recommended for Singapore to comply both with its national goals and with its new climate action plan to the UN Framework Convention on Climate Change.

     

Vascular endothelial growth factor and Kaposi's sarcoma cells in human skin grafts.

Human cancer cells often produce tumors in animal models that incompletely reproduce the histology of the parental tumor. Kaposi's sarcoma (KS) cells, in particular, have not produced durable angiogenic lesions in animal models that resemble those of KS in humans. We investigated the contribution of transformed KS cells, vascular endothelial growth factor (VEGF), and human skin tissue on tumor development in a human skin graft/mouse model. High levels of serum VEGF (322 pg/ml) were seen in HIV-1-infected persons with KS compared with HIV-1-infected persons without KS (115 pg/ml). Human KS lesions expressed VEGF in the spindle cells. Transformed KS cells expressed the mitogenically active 121-amino acid and 165-amino acid isoforms of VEGF. Tumors induced by KS cells implanted in the SCID mice grew preferentially in human skin grafts rather than in ungrafted murine skin. Tumors induced in the presence of human skin grafts developed numerous lumens expressing alpha(v)beta(3) integrin. KS cells inoculated with neutralizing anti-VEGF antibody did not form tumors. This study supports an important role for VEGF in tumor development and shows how a human tissue can preferentially promote tumor growth.     

Beta-blocker timolol alleviates hyperglycemia-induced cardiac damage via inhibition of endoplasmic reticulum stress

Current data support that pharmacological modulators of endoplasmic reticulum stress (ERS) have therapeutic potential for diabetic individuals. Therefore, we aimed to examine whether timolol, having free radical-scavenger action, besides being a β-blocker, exerts a cardioprotective effect via inhibition of ERS response in diabetic rats in a comparison with an antioxidant N-acetylcysteine (NAC). Histopathological data showed that either timolol- or NAC-treatment of diabetic rats prevented the changes in mitochondria and nucleus of the cardiac tissue while they enhanced the cellular redox-state in heart as well. The levels of ER-targeted cytoprotective chaperones GRP78 and calnexin, unfolded protein response signaling protein CHO/Gadd153 besides the levels of calpain, BCL-2, phospho-Akt, PUMA, and PML in the hearts from diabetic rats, treated with either timolol or NAC, are found to be similar among these groups, although all these parameters were markedly preserved in the untreated diabetics compared to those of the controls. Taken into consideration how important a balanced-ratio between anti-apoptotic and pro-apoptotic proteins for the maintenance mitochondria/ER function, our results suggest that ERS in diabetic rat heart is mediated by increased oxidative damage, which in turn triggers cardiac dysfunction. Moreover, we also demonstrated that timolol treatment of diabetic rats, similar to NAC treatment, induced a well-controlled redox-state and apoptosis in cardiac myocardium. We, thus for the first time, report that cardioprotective effect of timolol seems to be associated with normalization of ER function due to its antioxidant action in cardiomyocytes even under hyperglycemia.     

The hepatoprotective effects of Hypericum perforatum L. on hepatic ischemia/reperfusion injury in rats

Little is known about the effective role of Hypericum perforatum on hepatic ischemia–reperfusion (I/R) injury in rats. Hence, albino rats were subjected to 45 min of hepatic ischemia followed by 60 min of reperfusion period. Hypericum perforatum extract (HPE) at the dose of 50 mg/kg body weight (HPE₅₀) was intraperitonally injected as a single dose, 15 min prior to ischemia. Rats were sacrificed at the end of reperfusion period and then, biochemical investigations were made in serum and liver tissue. Liver tissue homogenates were used for the measurement of malondialdehyde (MDA), catalase (CAT) and glutathione peroxidase (GPx) levels. At the same time alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) were assayed in serum samples and compared statistically. While the ALT, AST, LDH activities and MDA levels were significantly increased, CAT and GPx activities significantly decreased in only I/R-induced control rats compared to normal control rats (p < 0.05). Treatment with HPE₅₀ significantly decreased the ALT, AST, LDH activities and MDA levels, and markedly increased activities of CAT and GPx in tissue homogenates compared to I/R-induced rats without treatment–control group (p < 0.05). In oxidative stress generated by hepatic ischemia–reperfusion, H. perforatum L. as an antioxidant agent contributes an alteration in the delicate balance between the scavenging capacity of antioxidant defence systems and free radicals in favour of the antioxidant defence systems in the body.     

Carvacrol partially reverses symptoms of diabetes in STZ-induced diabetic rats

Little is known about the protective effects of carvacrol on the symptoms of streptozotocin induced diabetes in rats. Hence, this present study was designed to evaluate the protective effect of the strong antioxidant, carvacrol, on the symptoms of streptozotocin induced diabetes in rats. Carvacrol at the doses of 25 and 50 mg/kg body weight were orally administered to diabetic rats for a period of 7 days after the onset of diabetes. Food-water intake and body weight changes were daily recorded. Biochemical parameters such as serum glucose, insulin, total cholesterol, alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase were measured. Although treatment of diabetic rats with oral administration of carvacrol resulted in a slight reduction in serum glucose level and significant reduction in serum total cholesterol, alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase in comparison with diabetic control rats, there were no significant differences in serum insulin levels, food-water intake values and body weight changes. Despite the inadequacy of carvacrol on diabetes treatments, it was determined to have at least a partially protective role on liver enzymes.     

Clinical value of cell counts and indices in testicular fine needle aspiration cytology in primary infertility: diagnostic performance compared with histology

OBJECTIVE: To compare the diagnostic value of testicular fine needle aspiration (FNA) cytology with that of open biopsy in primary infertility and nonobstructive azospermia or severe oligozoospermia, to evaluate the reliability of percentage cell counts and cell indices. STUDY DESIGN: Thirty patients (21 azospermic and 9 severe oligozoospermic) who had samples for testicular FNA obtained from both testis (mean age = 28.7) and open biopsy were included in the prospective study. Primary infertility, history, complete physical examination, hormonal assay and testicular ultrasound data were evaluated. One case was excluded because of an unsatisfactory result in aspiration cytology. The percentage population of Sertoli cells and spermatogenetic cells, in addition to spermatic index, sertoli cell index and sperm-Sertoli cell indexes, was calculated. The statistical analysis was determined using the paired t test. RESULTS: Progressively increasing values of the Sertoli cell index and progressively decreasing values of the sperm--Sertoli cell index were seen in maturation arrest, hypospermatogenesis and Sertoli cell-only syndrome. The difference between mean counts and indices in normal spermatogenesis and other histologic categories was statistically significant (p < 0.05). CONCLUSION: Percentage cell counts and cell indices in testicular FNA significantly correlate with histological categories. In primary male infertility, testicular FNA can be performed instead of open biopsy.     

The distribution of the bft alleles among enterotoxigenic Bacteroides fragilis strains from stool specimens and extraintestinal sites

Enterotoxigenic Bacteroides fragilis (ETBF) has been implicated in diarrhoeal illness in animals and humans. Recent data suggest that ETBF is associated with flares of inflammatory bowel disease. Toxigenicity is attributed to expression of a toxin referred to as fragilysin, which stimulates fluid accumulation in ligated intestinal segments and alter the morphology of human intestinal cells. Three different isoforms or variants of the enterotoxin gene, designated bft-1, bft-2, and bft-3, have been identified. In this study we investigated the distribution of bft alleles among ETBF strains in stool specimens from patients with colon cancer (n: 31), the control patients (n: 8) and extraintestinal sources (n: 15). We used restriction fragment length polymorphism analysis of the PCR-amplified enterotoxin gene and sequencing the PCR-product to detect the isoforms of bft gene. Among the stool strains, bft-1 was found to be more common than bft-2; as it was detected 27 of 31 strains from colon cancer patients and 7 of 8 control strains. The bft-1 isoform was also found in almost all isolates from extraintestinal sites. No bft-3 subtype was detected among all tested strains.     

Hexokinase cellular trafficking in ischemia–reperfusion and ischemic preconditioning is altered in type I diabetic heart

Diabetes mellitus (DM) has been reported to alter the cardiac response to ischemia–reperfusion (IR). In addition, cardioprotection induced by ischemic preconditioning (IPC) is often impaired in diabetes. We have previously shown that the subcellular localisation of the glycolytic enzyme hexokinase (HK) is causally related to IR injury and IPC protective potential. Especially the binding of HK to mitochondria and prevention of HK solubilisation (HK detachment from mitochondria) during ischemia confers cardioprotection. It is unknown whether diabetes affects HK localisation during IR and IPC as compared to non-diabetes. In this study we hypothesize that DM alters cellular trafficking of hexokinase in response to IR and IPC, possibly explaining the altered response to IR and IPC in diabetic heart. Control (CON) and type I diabetic (DM) rat hearts (65 mg/kg streptozotocin, 4 weeks) were isolated and perfused in Langendorff-mode and subjected to 35 min I and 30 min R with or without IPC (3 times 5 min I). Cytosolic and mitochondrial fractions were obtained at (1) baseline, i.e. after IPC but before I, (2) 35 min I, (3) 5 min R and (4) 30 min R. DM improved rate-pressure product recovery (RPP; 71 ± 10 % baseline (DM) versus 9 ± 1 % baseline (CON) and decreased contracture (end-diastolic pressure: 24 ± 8 mmHg (DM) vs 77 ± 4 mmHg (CON)) after IR as compared to control, and was associated with prevention of HK solubilisation at 35 min I. IPC improved cardiac function in CON but not in DM hearts. IPC in CON prevented HK solubilisation at 35 min I and at 5 min R, with a trend for increased mitochondrial HK. In contrast, the non-effective IPC in DM was associated with solubilisation of HK and decreased mitochondrial HK at early reperfusion and a reciprocal behaviour at late reperfusion. We conclude that type I DM significantly altered cellular HK translocation patterns in the heart in response to IR and IPC, possibly explaining altered response to IR and IPC in diabetes.