Direct S-H Evidence Revealing the Photo-electrocatalytic Hydrogen Evolution Reaction Mechanism on CdS Using Surface-Enhanced Raman Spectroscopy.

Photoelectrocatalytic water splitting using metal sulfides is a promising method for green hydrogen production. However, in situ probing of the hydrogen evolution reaction (HER) on sulfides with excellent performance remains a challenge. Here, we construct Au@CdS core-shell nanoparticles to study the HER on CdS, a typical HER catalyst, by surface-enhanced Raman spectroscopy (SERS) using a "borrowing" strategy. We directly capture the spectroscopic evidence of S-H intermediate under HER condition, further verified by isotopic experiments. Moreover, the population of S-H intermediates is improved by injecting charge carriers through light illumination and the S-H bond is weakened by introducing Pt to form a Au@Pt@CdS structure to change the interfacial electronic structure, both of them resulting in significant HER performance improvement. These findings can deepen the understanding of the HER mechanism and offer strategies for designing of cost-effective HER catalyst with high performance.

Sulforaphane ameliorates high-fat diet-induced spermatogenic deficiency in mice†.

Sulforaphane (SFN), a dietary isothiocyanate that is mainly found in cruciferous vegetables, possesses anti-oxidative and anticancer activity and modulates inflammation. However, little is known about the role of SFN in obesity-related male reproductive defects. The present study aimed to investigate the effects of SFN on high-fat diet (HFD)-induced male spermatogenic impairment and further clarify the possible underlying mechanisms. In this study, 8-week-old mice were randomly divided into four groups. Mice were fed a normal diet or an HFD with or without SFN supplementation. Sulforaphane was subcutaneously injected at a dose of 0.5 mg/kg 5 days/week for 4 weeks beginning 8 weeks after initiation of the HFD. The results demonstrated that SFN could protect against HFD-induced reproductive dysfunction in male mice. Moreover, SFN also improved reproductive ability, as demonstrated by an increased pregnancy rate and decreased embryo resorption rate in comparison to the corresponding HFD group. We also observed a decrease in apoptosis and an attenuation of endoplasmic reticulum (ER) stress after SFN treatment. In vitro studies of mouse and human sperm samples also revealed that SFN protects against the palmitic acid-induced reduction in sperm viability and motility by inhibiting ER stress in an AMP-activated protein kinase (AMPK)-dependent manner. AMPK-dependent ER stress attenuation by SFN was further confirmed using AMPK knockout mice. Taken together, these data show that SFN protects against HFD-induced male reproductive dysfunction by inhibiting ER stress and apoptosis. These findings may be helpful for identifying new therapeutic methods to treat male infertility.

Accelerated bacterial detection in blood culture by enhanced acoustic flow cytometry (AFC) following peptide nucleic acid fluorescence in situ hybridization (PNA-FISH).

Bacteraemia is a risk factor for subsequent clinical deterioration and death. Current reliance on culture-based methods for detection of bacteraemia delays identification and assessment of this risk until after the optimal period for positively impacting treatment decisions has passed. Therefore, a method for rapid detection and identification of bacterial infection in the peripheral bloodstream in acutely ill patients is crucial for improved patient survival through earlier targeted antibiotic treatment. The turnaround time for current clinical laboratory methods ranges from 12 to 48 hours, emphasizing the need for a faster diagnostic test. Here we describe a novel assay for accelerated generic detection of bacteria in blood culture (BC) using peptide nucleic acid fluorescence in situ hybridization enhanced acoustic flow cytometry (PNA-FISH-AFC). For assay development, we used simulated blood cultures (BCs) spiked with one of three bacterial species at a low starting concentration of 10 CFU/mL: Escherichia coli, Klebsiella pneumoniae or Pseudomonas aeruginosa. Under current clinical settings, it takes a minimum of 12 hours incubation to reach positivity on the BacTEC system, corresponding to a bacterial concentration of 107-109 CFU/mL optimal for further analyses. In contrast, our PNA-FISH-AFC assay detected 103-104 CFU/mL bacteria in BC following a much shorter culture incubation of 5 to 10 hours. Using either PCR-based FilmArray assay or MALDI-TOF for bacterial detection, it took 7-10 and 12-24 hours of incubation, respectively, to reach the positive result. These findings indicate a potential time advantage of PNA-FISH-AFC assay for rapid bacterial detection in BC with significantly improved turnaround time over currently used laboratory techniques.

Human 8-oxoguanine-DNA glycosylase-1 is downregulated in human basal cell carcinoma.

Basal cell carcinoma (BCC) is the most common type of skin cancer and is a major public health problem in many Western countries. It usually occurs as a consequence of exposure to ultraviolet radiation (UV) with sunlight. The DNA photolesion 8-oxo-7,8-dihydroguanine (8-oxo-dG) is caused by reactive oxygen species (ROS) produced in response to UVA, UVB, and oxidative metabolism. If this damaged DNA is not repaired prior to cell division, then gene mutations may persist in daughter cells. Human 8-oxoguanine-DNA glycosylase 1 (hOGG1) is the main enzyme that excises 8-oxo-dG from damaged DNA via the base-excision repair pathway. However, the role of hOGG1 in human skin cancer is unknown. In this study, using immunohistochemical staining, we found low hOGG1 protein expression in human BCC compared to overlying epidermis or normal epidermis. We also found higher levels of 8-oxo-dG within the BCC compared to the basal layers of epidermis overlying the BCC lesions (E-BCC). The results suggest that low expression of hOGG1 within BCC results in accumulation of ROS generated 8-oxo-dG due to low levels of DNA repair, thereby implicating hOGG1 in human BCC carcinogenesis. These ROS are likely to be produced by the cancer cells during metabolism, as the BCC nests are too deep for UV to reach. Our data suggests that procedures that increase expression of hOGG1 within BCC, or protect from ROS may be beneficial for reducing progression of BCC.

Ultraviolet A within sunlight induces mutations in the epidermal basal layer of engineered human skin.

The ultraviolet B (UVB) waveband within sunlight is an important carcinogen; however, UVA is also likely to be involved. By ascribing mutations to being either UVB or UVA induced, we have previously shown that human skin cancers contain similar numbers of UVB- and UVA-induced mutations, and, importantly, the UVA mutations were at the base of the epidermis of the tumors. To determine whether these mutations occurred in response to UV, we exposed engineered human skin (EHS) to UVA, UVB, or a mixture that resembled sunlight, and then detected mutations by both denaturing high-performance liquid chromatography and DNA sequencing. EHS resembles human skin, modeling differential waveband penetration to the basal, dividing keratinocytes. We administered only four low doses of UV exposure. Both UVA and UVB induced p53 mutations in irradiated EHS, suggesting that sunlight doses that are achievable during normal daily activities are mutagenic. UVA- but not UVB-induced mutations predominated in the basal epidermis that contains dividing keratinocytes and are thought to give rise to skin tumors. These studies indicate that both UVA and UVB at physiological doses are mutagenic to keratinocytes in EHS.

Human 8-oxoguanine-DNA glycosylase 1 protein and gene are expressed more abundantly in the superficial than basal layer of human epidermis.

Human 8-oxoguanine-DNA glycosylase 1 (hOGG1) repairs 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) which results from oxidation of guanine. Reactive oxygen species (ROS) formed in response to ultraviolet (UV) radiation cause this DNA damage, which is involved in pathological processes such as carcinogenesis and aging. The initiation of skin tumors probably requires penetration of UV to the actively dividing basal layer of the epidermis in order for acute damage to become fixed as mutations. Previously, the majority of UVB fingerprint mutations have been found in the upper layers of human skin tumors, while UVA mutations have been found mostly in the lower layer. Our aim was to determine whether this localization of UVA-induced DNA damage is related to stratification of the repair-enzyme hOGG1. Anti-hOGG1 immunohistochemical staining of frozen sections of human foreskin, adult buttock skin, and reconstructed human skin samples showed the highest expression of hOGG1 in the superficial epidermal layer (stratum granulosum). Study of the hOGG1 mRNA expression again showed the highest level in the upper region of the epidermis. This was not regulated by UV irradiation but by the differentiation state of keratinocytes as calcium-induced differentiation increased hOGG1 gene expression. UVA-induced 8-oxo-dG was repaired more rapidly in the upper layer of human skin compared to the lower layers. Our results indicate that weaker expression of the nuclear form of hOGG1 enzyme in the basal cells of the epidermis may lead to a lack of DNA repair in these cells and therefore accumulation of UVA-induced oxidative DNA mutations.