Transmembrane capability of DNA origami sheet enhanced by 3D configurational changes.

DNA origami-engineered nanostructures are widely used in biomedical applications involving transmembrane delivery. Here, we propose a method to enhance the transmembrane capability of DNA origami sheets by changing their configuration from two-dimensional to three-dimensional. Three DNA nanostructures are designed and constructed, including the two-dimensional rectangular DNA origami sheet, the DNA tube, and the DNA tetrahedron. The latter two are the variants of the DNA origami sheet with three-dimensional morphologies achieved through one-step folding and multi-step parallel folding separately. The design feasibility and structural stability of three DNA nanostructures are confirmed by molecular dynamics simulations. The fluorescence signals of the brain tumor models demonstrate that the tubular and the tetrahedral configurational changes could dramatically increase the penetration efficiency of the original DNA origami sheet by about three and five times, respectively. Our findings provide constructive insights for further rational designs of DNA nanostructures for transmembrane delivery.

Cell pairing for biological analysis in microfluidic devices.

Cell pairing at the single-cell level usually allows a few cells to contact or seal in a single chamber and provides high-resolution imaging. It is pivotal for biological research, including understanding basic cell functions, creating cancer treatment technologies, developing drugs, and more. Laboratory chips based on microfluidics have been widely used to trap, immobilize, and analyze cells due to their high efficiency, high throughput, and good biocompatibility properties. Cell pairing technology in microfluidic devices provides spatiotemporal research on cellular interactions and a highly controlled approach for cell heterogeneity studies. In the last few decades, many researchers have emphasized cell pairing research based on microfluidics. They designed various microfluidic device structures for different biological applications. Herein, we describe the current physical methods of microfluidic devices to trap cell pairs. We emphatically summarize the practical applications of cell pairing in microfluidic devices, including cell fusion, cell immunity, gap junction intercellular communication, cell co-culture, and other applications. Finally, we review the advances and existing challenges of the presented devices and then discuss the possible development directions to promote medical and biological research.

A tetrahedral DNA nanorobot with conformational change in response to molecular trigger.

Dynamic DNA origami nanostructures that respond to external stimuli are promising platforms for cargo delivery and nanoscale sensing. However, the low stability of such nanostructures under physiological conditions presents a major obstacle for their use in biomedical applications. This article describes a stable tetrahedral DNA nanorobot (TDN) programmed to undergo a controlled conformational change in response to epithelial cell adhesion molecule (EpCAM), a molecular biomarker specifically expressed on the circulating tumor cells. Multiresolution molecular dynamics simulations verified the overall stability of the folded TDN design and characterized local distortions in the folded structure. Atomic force microscopy and gel electrophoresis results showed that tetragonal structures are more stable than unfolded DNA origami sheets. Live cell experiments demonstrated the low cytotoxicity and target specificity of TDN. In summary, the proposed TDN can not only effectively resist nuclease catalysis but also has the potential to monitor EpCAM-positive cells precisely.

Automated Cell Mechanical Characterization by On-Chip Sequential Squeezing: From Static to Dynamic.

The mechanical properties of cells are harmless biomarkers for cell identification and disease diagnosis. Although many systems have been developed to evaluate the static mechanical properties of cells for biomedical research, their robustness, effectiveness, and cost do not meet clinical requirements or the experiments with a large number of cell samples. In this paper, we propose an approach for on-chip cell mechanical characterization by analyzing the dynamic behavior of cells as they pass through multiple constrictions. The proposed serpentine microfluidic channel consisted of 20 constrictions connected in series and divided into five rows for tracking cell dynamic behavior. Assisted by computer vision, the squeezing time of each cell through five rows of constrictions was automatically collected and filtered to evaluate the cell's mechanical deformability. We observed a decreasing passage time and increasing dynamic deformability of the cells as they passed through the multiple constrictions. The deformability increase rate of the HeLa cells was eight times greater than that of MEF cells. Moreover, the weak correlation between the deformability increase rate and the cell size indicated that cell recognition based on measuring the deformability increase rate could hardly be affected by the cell size variation. These findings showed that the deformability increase rate of the cell under on-chip sequential squeezing as a new index has great potential in cancer cell recognition.

Endoluminal Motion Recognition of a Magnetically-Guided Capsule Endoscope Based on Capsule-Tissue Interaction Force.

A magnetically-guided capsule endoscope, embedding flexible force sensors, is designed to measure the capsule-tissue interaction force. The flexible force sensor is composed of eight force-sensitive elements surrounding the internal permanent magnet (IPM). The control of interaction force acting on the intestinal wall can reduce patient's discomfort and maintain the magnetic coupling between the external permanent magnet (EPM) and the IPM during capsule navigation. A flexible force sensor can achieve this control. In particular, by analyzing the signals of the force sensitive elements, we propose a method to recognize the status of the motion of the magnetic capsule, and provide corresponding formulas to evaluate whether the magnetic capsule follows the motion of the external driving magnet. Accuracy of the motion recognition in Ex Vivo tests reached 94% when the EPM was translated along the longitudinal axis. In addition, a method is proposed to realign the EPM and the IPM before the loss of their magnetic coupling. Its translational error, rotational error, and runtime are 7.04 ± 0.71 mm, 3.13 ± 0.47∘, and 11.4 ± 0.39 s, respectively. Finally, a control strategy is proposed to prevent the magnetic capsule endoscope from losing control during the magnetically-guided capsule colonoscopy.

Citrus Naringenin Increases Neuron Survival in Optic Nerve Crush Injury Model by Inhibiting JNK-JUN Pathway.

Traumatic nerve injury activates cell stress pathways, resulting in neuronal death and loss of vital neural functions. To date, there are no available neuroprotectants for the treatment of traumatic neural injuries. Here, we studied three important flavanones of citrus components, in vitro and in vivo, to reveal their roles in inhibiting the JNK (c-Jun N-terminal kinase)-JUN pathway and their neuroprotective effects in the optic nerve crush injury model, a kind of traumatic nerve injury in the central nervous system. Results showed that both neural injury in vivo and cell stress in vitro activated the JNK-JUN pathway and increased JUN phosphorylation. We also demonstrated that naringenin treatment completely inhibited stress-induced JUN phosphorylation in cultured cells, whereas nobiletin and hesperidin only partially inhibited JUN phosphorylation. Neuroprotection studies in optic nerve crush injury mouse models revealed that naringenin treatment increased the survival of retinal ganglion cells after traumatic optic nerve injury, while the other two components had no neuroprotective effect. The neuroprotection effect of naringenin was due to the inhibition of JUN phosphorylation in crush-injured retinal ganglion cells. Therefore, the citrus component naringenin provides neuroprotection through the inhibition of the JNK-JUN pathway by inhibiting JUN phosphorylation, indicating the potential application of citrus chemical components in the clinical therapy of traumatic optic nerve injuries.

Photosensitized protein damage by dimethoxyphosphorus(V) tetraphenylporphyrin.

For the purpose of the basic study of photodynamic therapy, the activity of the water-soluble P(V)porphyrin, dimethoxyP(V)tetraphenylporphyrin chloride (DMP(V)TPP), on photosensitized protein damage was examined. The quantum yield of singlet oxygen generation by DMP(V)TPP (0.64) was comparable with that of typical porphyrin photosensitizers. Absorption spectrum measurement demonstrated the binding interaction between DMP(V)TPP and human serum albumin, a water-soluble protein. Photo-irradiated DMP(V)TPP damaged the amino acid residue of human serum albumin, resulting in the decrease of the fluorescence intensity from the tryptophan residue of human serum albumin. A singlet oxygen quencher, sodium azide, could not completely inhibit the damage of human serum albumin, suggesting that the electron transfer mechanism contributes to protein damage as does singlet oxygen generation. The decrease of the fluorescence lifetime of DMP(V)TPP by human serum albumin supported the electron transfer mechanism. The estimated contribution of the electron transfer mechanism is 0.64. These results suggest that the activity of DMP(V)TPP can be preserved under lower oxygen concentration condition such as tumor.

Extremely efficient and long lifetime fluorescence of cis-stilbene contained in a rigid dendrimer.

The fluorescence quantum yield of cis-stilbene-cored rigid polyphenylene dendrimer (cis-G2) is 20% even at room temperature. Moreover, the fluorescence lifetime of cis-G2 is twice as long as that of the corresponding trans-isomer.

Control of singlet oxygen generation photosensitized by meso-anthrylporphyrin through interaction with DNA.

To control the activity of photosensitized singlet oxygen ((1)O(2)) generation, the electron donor-connecting porphyrin, 5-(9'-anthryl)-10,15,20-tris(p-pyridyl)porphyrin (AnTPyP), was designed and synthesized. AnTPyP became water-soluble by the protonation of the pyridyl moieties in the presence of 5 mM trifluoroacetic acid (pH 2.3). The photoexcited state of the porphyrin ring in an AnTPyP molecule was effectively deactivated by intramolecular electron transfer from the anthracene moiety within 0.04 ns in an aqueous solution. The deactivation was suppressed by the interaction with a DNA strand, resulting in the elongation of the lifetime of the porphyrin excited state and the enhancement of the fluorescence intensity. Furthermore, it was confirmed that the interaction enabled the photoexcited AnTPyP to generate (1)O(2). Selective (1)O(2) generation by forming a complex with DNA should be the initial step to realize the target selective photodynamic therapy.

Long-term survival and risk of second cancers after radiotherapy for cervical cancer.

PURPOSE: To evaluate the risk of second cancers after cervical cancer treated with radiotherapy for Asian populations. METHODS AND MATERIALS: We reviewed 2,167 patients with cervical cancer undergoing radiotherapy between 1961 and 1986. Intracavitary brachytherapy was performed with high-dose rate source (82%) or low-dose rate source (12%). Relative risk (RR), absolute excess risk (AR), and cumulative risk of second cancer were calculated using the Japanese disease expectancy table. For 1,031 patients, the impact of smoking habit on the increasing risk of second cancer was also evaluated. RESULTS: The total number of person-years of follow-up was 25,771, with 60 patients being lost to follow-up. Among the 2,167 patients, 1,063 (49%) survived more than 10 years. Second cancers were observed in 210 patients, representing a significant 1.2-fold risk (95% confidence interval [CI], 1.1-1.4) of developing second cancer compared with the general population, 1.6% excess risk per person per decade of follow-up, and elevating cumulative risk up to 23.8% (95% CI, 20.3-27.3) at 30 years after radiotherapy. The RR of second cancer was 1.6-fold for patients with the smoking habit and 1.4-fold for those without. CONCLUSIONS: Small but significant increased risk of second cancer was observed among Japanese women with cervical cancer mainly treated with high-dose rate brachytherapy. Considering the fact that about half of the patients survived more than 10 years, the benefit of radiotherapy outweighs the risk of developing second cancer.

Long-term results of high-dose rate intracavitary brachytherapy for squamous cell carcinoma of the uterine cervix.

BACKGROUND: The authors performed a long-term follow-up study to evaluate the efficacy and late toxicity of high-dose rate intracavitary brachytherapy (HDR-ICBT) for cervical carcinoma. METHODS: From 1968 to 1986, 1148 patients with Stage IB to IVB squamous cell carcinoma of the cervix (staging was performed according to the International Federation of Gynecology and Obstetrics) were treated with a combination of external beam radiotherapy (EBRT) and HDR-ICBT. For patients with early-stage disease, 20 gray (Gy) of EBRT was delivered to the whole pelvis, followed by 24 Gy/4 fractions of HDR-ICBT and 30 Gy of central-shielding EBRT. For patients with advanced-stage disease, 20-40 Gy of whole pelvic EBRT was administered, followed by 24 Gy/4 fractions of ICBT and 30-10 Gy of central-shielding EBRT. The overall treatment time was approximately 6 weeks. Among survivors, the follow-up rate was 98% and the median follow-up duration was 22 years. RESULTS: The 10-year pelvic tumor control rates were 93% for patients with Stage IB disease, 82% for patients with Stage II disease, and 75% for patients with Stage III disease. The 10-year overall and cause-specific survival rates were 74% and 89% for patients with Stage IB disease, 52% and 74% for patients with Stage II disease, and 42% and 59% for patients with Stage III disease, respectively. The 10-year actuarial rates of major complications were 4.4% in the rectosigmoid colon, 0.9% in the bladder, and 3.3% in the small intestines. CONCLUSIONS: The results of the current study suggest that the combination of EBRT and HDR-ICBT according to the authors' protocol provided outcomes that were comparable to those of the conventional low-dose rate brachytherapy with acceptable rates of late complications in the treatment of cervical carcinoma.

Effects of benzyl ether type dendrons as hole-harvesting antennas, and shielding for the neutralization of stilbene core radical cations with chloride ion during two-photon ionization of stilbene dendrimers having stilbene core and benzyl ether type dendrons.

The two-photon ionization (TPI) process (308 and 266 nm) of stilbene dendrimers having a stilbene core and benzyl ether type dendrons has been investigated in an acetonitrile and 1,2-dichloroethane mixture (3:1) in order to elucidate the dendrimer effects. The quantum yield of the formation of stilbene core radical cation during the 308-nm TPI was independent of the dendron generation of the dendrimers, whereas a generation dependence of the quantum yield of the radical cation was observed during the 266-nm TPI, where both the stilbene core and benzyl ether type dendron were ionized, suggesting that the subsequent hole transfer occurs from the dendron to the stilbene core, and that the dendron acts as a hole-harvesting antenna. The neutralization rate of the stilbene core radical cation with the chloride ion, generated from the dissociative electron capture by 1,2-dichloroethane, decreased with the increase in the dendrimer generation, suggesting that the dendron is an effective shield of the stilbene core radical cation against the chloride ion.

Photoisomerisation and fluorescence behaviour of polyphenylene-based stilbene dendrimers.

The photoinduced structural changes of three polyphenylene-based stilbene dendrimers, G1, G2, and G3, has been studied. They all exhibit fluorescence emission with considerably higher quantum efficiency and longer fluorescence lifetimes compared with the parent stilbene. These dendrimers undergo mutual cis --> trans isomerisation on direct irradiation with 310 nm light at room temperature. In a solvent glass at 77 K, one-way cis --> trans isomerisation was observed for G2. A volume-conserving isomerisation mechanism is presumed to be operating in the cis-to-trans isomerisation of G2 at 77 K.

Long-term survival in advanced small cell carcinoma of the colorectum: report of a case.

A 47-year-old man was referred to our institution with bloody diarrhea. An endoscopic examination showed a 6-cm tumor with central ulceration in the upper rectum. A high anterior resection of the rectum with lymphadenectomy was performed with the diagnosis of colorectal cancer. An intraoperative cytological examination found many free cancer cells in the peritoneal lavage fluid. Histologically, the tumor had invaded deeply and exposed the serosa, and was diagnosed as a small cell carcinoma of the colorectum with marginal lymph node metastasis. The patient is alive without any evidence of recurrence approximately 37 months after surgery despite the aggressive clinical behavior and a high mortality rate associated with this tumor. This case of an advanced small cell carcinoma of the colorectum showed a good outcome even though the cytology of the peritoneal lavage was positive.