Synergistic antitumor efficacy of rMV-Hu191 and Olaparib in pancreatic cancer by generating oxidative DNA damage and ROS-dependent apoptosis

BACKGROUND

Malignancies with BRCA1/2 deficiencies are particularly sensitive to PARP inhibitors. Thus, combining PARP inhibitors with agents that impair DNA damage repair to treat BRCA1/2 wild-type PDAC could broaden the clinical use of these promising PARP inhibitors. Here we examined the synergism and mechanism of oncolytic measles virus (rMV-Hu191) with a PARP inhibitor (Olaparib) in vitro and in vivo.

METHODS

The cell viability assay, cell cycle analysis, colony formation assay, TCID 50 method, western blotting, flow cytometry, DNA comet assay, Mice bearing PDAC xenografts, IF, IHC and TUNEL assay were performed to explore the antitumor efficacy and underlying mechanisms.

RESULTS

In this study, we explored the antitumor activities of rMV-Hu191 and Olaparib in two PDAC cell lines harboring wild-type BRCA1/2 genes. Compared to monotherapy, the combination of rMV-Hu191 and Olaparib was able to synergistically cause growth arrest, apoptotic cell death and DNA damage, accompanying with excessive oxidative stress. Mechanistically, the data indicated that the observed synergy depended on the oxidative DNA damage and ROS-dependent apoptosis generating by rMV-Hu191 combined with Olaparib in human PDAC cells. Tumor inhibition and prolonged survival of PDAC mice xenografts in vivo confirmed the synergism of combinational treatment with trivial side-effects.

CONCLUSIONS

Our findings firstly suggested that combination treatment with rMV-Hu191 and Olaparib had a profound and synergistic therapeutic effect against human PDAC through synthetic lethality. In conclusion, we recommend combining oncolytic rMV-Hu191 with a PARP inhibitor (Olaparib) as a novel therapeutic strategy and provided a potential mechanism for advanced PDAC regardless of BRCA mutation status.

[Application of single anterior teeth defect with computer-aided design and computer-aided manufacturing polymethyl methacrylate single-retainer resin-bonded fixed dental prosthesis in children]

Objective: To explore the clinical effect of computer-aided design and computer-aided manufacturing (CAD/CAM) polymethyl methacrylate (PMMA) single-retainer resin-bonded fixed dental prosthesis (RBFDP) for single anterior teeth defect. Methods: A total of 14 children between 10-14 years old (male 8, female 6) who visited the Department of Pediatric Dentistry, School of Stomatology, The Fourth Military Medical University from March to December 2022 with single anterior teeth loss were enrolled in this study. The intraoral scanner was used to obtain their digital impressions, and then the data were imported into CAD software. The single-retainer RBFDP was designed by the CAD software and was manufactured by milling equipment using CAD/CAM PMMA disk. The prosthesis was then tried-in and bonded to the abutment teeth with resin cement and evaluated in a 12 month follow-up observation. The marginal discoloration, marginal adaptation, color match, secondary caries, the occurrence of fractures and loose of abutment tooth were examined on the basis of the modified United States Public Health Services evaluation system. The evaluation was divided into three scores, in which score A indicated ideal restoration effect, score B means that the restoration effect was acceptable (evaluation of restoration integrity, loose of abutment teeth and secondary caries excluded), and score C indicates that the restoration effect is not good. Results: All the 14 CAD/CAM PMMA single-retainer RBFDP had good marginal adaptation and color match with no marginal discoloration, no secondary caries, no fracture of restorations and no abnormal loose of the abutment teeth. All of the six criteria achieved score A evaluation after a three month follow-up observation. One restoration was classified as score B for fracture after a six month follow-up observation, while two restoration were classified as score B for marginal discoloration after 12 month follow-up observation. Conclusions: The CAD/CAM PMMA single-retainer RBFDP was clinically effective in restoration of single anterior teeth defect in children.

Construction of UiO-66-NH2 decorated by MoS2 QDs as photocatalyst for rapid and effective visible-light driven Cr(VI) reduction

The photoactive metal-organic frameworks (MOFs) are good candidates for photocatalysts, but the quick electron-hole pairs recombination has greatly restricted the photocatalytic ability of MOFs. To improve the photoactivity of MOFs, MOFs-based composite materials have been extensively studied. Here, we successfully integrated MoS2 quantum dots (QDs) with UiO-66-NH2 for the first time under hydrothermal conditions. The as-prepared MoS2 QDs/UiO-66-NH2 (MS-U) had good visible light response ability (absorption edge at 445 nm), and charge separation and transfer ability, which lays the foundation for the photocatalytic Cr(VI) reduction. Photocatalytic studies revealed that MoS2 QDs-5/UiO-66-NH2 (MS-U-5) had superior Cr(VI) reduction activity than pure MoS2 QDs and UiO-66-NH2. MS-U-5 could remove 98% Cr(VI) at pH= 2 with visible light irradiation for 20 min, which is the fastest visible light driven Cr(VI) reduction rate among the reported MOFs-based composite photocatalysts without the presence of any cocatalysts or scavengers as far as we know. Importantly, MS-U-5 could be reused at least three times. In the end, the possible electron transfer path and mechanism of Cr(VI) reduction was also investigated.

Recombinant measles virus vaccine rMV-Hu191 exerts an oncolytic effect on esophageal squamous cell carcinoma via caspase-3/GSDME-mediated pyroptosis

Oncolytic viruses have recently been proven to be an effective and promising cancer therapeutic strategy, but there is rare data about oncolytic therapy in esophageal squamous cell carcinoma (ESCC), especially oncolytic measles virotherapy. Therefore, this study aimed to explore whether the recombinant measles virus vaccine strain rMV-Hu191 has an oncolytic effect against ESCC cells in vitro and in vivo and elucidate the underlying mechanisms. Our results showed that rMV-Hu191 could efficiently replicate in and kill ESCC cells through caspase-3/GSDME-mediated pyroptosis. Mechanistically, rMV-Hu191 triggers mitochondrial dysfunction to induce pyroptosis, which is mediated by BAK (BCL2 antagonist/killer 1) or BAX (BCL2 associated X). Further analysis revealed that rMV-Hu191 activates inflammatory signaling in ESCC cells, which may enhance the oncolytic efficiency. Moreover, intratumoral injection of rMV-Hu191 induced dramatic tumor regression in an ESCC xenograft model. Collectively, these findings imply that rMV-Hu191 exhibits an antitumor effect through BAK/BAX-dependent caspase-3/GSDME-mediated pyroptosis and provides a potentially promising new therapy for ESCC treatment.

Recombinant Chinese Hu191 measles virus exhibits a significant antitumor activity against nephroblastoma mediated by immunogenic form of apoptosis

In previous studies oncolytic measles viruses (MVs) have shown significant antitumor activity against various tumors. In our research recombinant MV-Hu191 (rMV-Hu191), established via reverse genetics technology and expressing enhanced green fluorescent protein (EGFP), was evaluated for its therapeutic effects and related mechanisms against nephroblastoma cell lines. We built three different constructs based on rMV-Hu191 to express EGFP effectively. Our experiments showed that rMV-Hu191 expressing EGFP could efficiently infect and replicate in nephroblastoma cell lines. Caspase-induced apoptosis exerted a significant impact on MV-induced cell death, which was accompanied by emission of cellular ATP and high-mobility group protein 1 (HMGB1) and by translocation of calreticulin (CRT). Intratumoral injection of rMV-Hu191-EGFP resulted in significant regression of tumors in a G401 xenograft model. Our results indicate that the MV-Hu191 strain, which is widely used in China, is an appropriate vector for expression of foreign genes and could serve as a potentially good candidate for nephroblastoma therapy mediated by induction of apoptosis-associated immunogenic cell death (ICD).

A recombinant Chinese measles virus vaccine strain rMV-Hu191 inhibits human colorectal cancer growth through inducing autophagy and apoptosis regulating by PI3K/AKT pathway

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The recombinant Chinese measles virus vaccine strain rMV-Hu191 induced efficient infection and oncolytic effects in human CRC both in vitro and in vivo.

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rMV-Hu191 induced the caspase-dependent apoptosis and complete autophagy in CRC cells.

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Autophagy served as a protective role in human CRC cells’ apoptosis induced by rMV-Hu191.

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rMV-Hu191-induced autophagy and apoptosis were regulated by the PI3K/AKT signaling pathway in human CRC.

The potential therapeutic effects of oncolytic measles virotherapy have been verified against plenty of malignancies. However, the oncolytic effects and underlying mechanisms of the recombinant Chinese measles virus vaccine strain Hu191 (rMV-Hu191) against human colorectal cancer (CRC) remain elusive. In this study, the antitumor effects of rMV-Hu191 were evaluated in CRC both in vitro and in vivo. From our data, rMV-Hu191 induced remarkably caspase-dependent apoptosis and complete autophagy in vitro. In mice bearing CRC xenografts, tumor volume was remarkably suppressed and median survival was prolonged significantly with intratumoral treatment of rMV-Hu191. To gain further insight into the relationship of rMV-Hu191-induced apoptosis and autophagy, we utilized Rapa and shATG7 to regulate autophagy. Our data suggested that autophagy was served as a protective role in rMV-Hu191-induced apoptosis in CRC. PI3K/AKT signaling pathway as one of the common upstream pathways of apoptosis and autophagy was activated in CRC after treatment with rMV-Hu191. And inhibition of PI3K/AKT pathway using LY294002 was accompanied by enhanced apoptosis and decreased autophagy which suggested that PI3K/AKT pathway promoted rMV-Hu191-induced autophagy and inhibited rMV-Hu191-induced apoptosis. This is the first study to demonstrate that rMV-Hu191 could be used as a potentially effective therapeutic agent in CRC treatment. As part of the underlying cellular mechanisms, apoptosis and autophagy were involved in the oncolytic effects generated by rMV-Hu191. And the cross-talk between these two processes and the PI3K/AKT signaling pathway was well identified.

[The value of MR T2WI signal intensity related parameters for predicting pathological complete response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer]

Objective: To evaluate the value of T2WI signal intensity related parameters that can be obtained by magnetic resonance imaging (MRI) for predicting pathological complete response (pCR) after neoadjuvant chemoradiotherapy (nCRT) in patients with locally advanved rectal cancer (LARC). Methods: Signal Intensity of Tumor (SIT) and Signal Intensity of Tumor/Muscle (SIT/M) of MR T2WI before and after neoadjuvant chemoradiotherapy of 101 patients with locally advanced rectal cancer were evaluated by two experienced readers independently. Signal Intensity of Tumor Reduction Rate (SITRR) and Signal Intensity of Tumor/Muscle Reduction Rate (SIT/MRR) were calculated. The difference of related parameters of T2WI tumor signal intensity between the pCR and the non-pCR group were analyzed. Receiver operating characteristic (ROC) analysis was used to assess the diagnostic performance for predicting pCR. Results: Of the 101 patients, 18 were in pCR group and 83 were in non-pCR group. In all patients, the SITpre, SITpost, SITRR, SIT/Mpre, SIT/Mpost and SIT/MRR measured by reader 1 were 197.0 (133.0), 144.2 (69.7), 0.4% (0.5%), 2.6 (0.6), 3.0 (2.3) and 0.4 (0.2)% in pCR group, and 227.0 (99.0), 205 (95.4), 0.1% (0.6%), 2.6 (0.6), 2.6 (1) in non-pCR group, respectively. SITpre, SITpost, SITRR, SIT/Mpre, SIT/Mpost and SIT/MRR measured by reader 2 were 193.0 (135.0), 143.0 (69.8), 0.4% (0.2%), 2.6 (0.6), 1.5 (0.5) and 0.39% (0.2%) in pCR group, and 234.0(108.0), 203(96.5), 0.1% (0.3%), 2.6 (0.6%), 1.7 (0.7) and 0.25% (0.2%) in non-pCR group, respectively. Between the pCR and non-pCR group, there were significant differences in SITpost, SIT/Mpost and SIT/MRR measured by both readers (all P<0.01), but there was no significant differences in SITpre and SIT/Mpre (P>0.05). The difference of SITRR measured by reader 1 was not statistically significant (P=0.415), while the difference of SITRR measured by reader 2 was statistically significant (P=0.001). In patients with rectal non-mucinous adenocarcinoma, SITpost, SIT/Mpost, SITRR and SIT/MRR measured by two physicians were still statistically significant between the pCR and non-pCR group (all P<0.01), but SITpre and SIT/Mpre had no significant difference (P>0.05). ROC curve analysis showed that in all patients, the area under curve (AUC) of SITpost, SIT/Mpost and SIT/MRR for predicting pCR to neoadjuvant chemoradiotherapy in locally advanced rectal cancer was 0.694-0.762, the sensitivity was 68.2%-77.3%, and the specificity was 63.6%-77.3%. In rectal non-mucinous adenocarcinoma patients, the AUC, sensitivity and specificity was 0.704-0.764, 62.7%-78.9% and 66.2%-84.2%, respectively. Conclusions: T2WI signal intensity related parameters are potential predictors for pCR in locally advanced rectal cancer after neoadjuvant chemoradiptherapy. The predictive value is higher in non-mucinous adenocarcinoma.

A recombinant measles virus vaccine strain rMV-Hu191 has oncolytic effect against human gastric cancer by inducing apoptotic cell death requiring integrity of lipid raft microdomains

Live-attenuated strain of measles virus (MV) has oncolytic effect. In this study, the antitumor effect of rMV-Hu191, a recombinant Chinese Hu191 MV generated in our laboratory by efficient reverse genetics system, was evaluated in gastric cancer (GC). From our data, rMV-Hu191 induced cytopathic effects and inhibited tumor proliferation both in vitro and in vivo by inducing caspase-dependent apoptosis. In mice bearing GC xenografts, tumor size was reduced and survival was prolonged significantly after intratumoral injections of rMV-Hu191. Furthermore, lipid rafts, a type of membrane microdomain with specific lipid compositions, played an important role in facilitating entry of rMV-Hu191. Integrity of lipid rafts was required for successful viral infection as well as subsequent cell apoptosis, but was not required for viral binding and replication. CD46, a MV membrane receptor, was found to be partially localized in lipid rafts microdomains. This is the first study to demonstrate that Chinese Hu191 MV vaccine strain could be used as a potentially effective therapeutic agent in GC treatment. As part of the underlying cellular mechanism, the integrity of lipid rafts is required for viral entry and to exercise the oncolytic effect.

[Combined T2-weighted and diffusion-weighted MR imaging for staging of rectal cancers]

Objective: To compare the diagnostic value of T2 weighted imaging (T2WI), diffusion-weighted imaging (DWI), and T2WI+ DWI magnetic resonance imaging (MRI) for staging of rectal cancers for improving the accuracy of tumor staging. Methods: From January 2011 to December 2013, 120 cases of rectal cancers proved by colonoscopy without receiving any anti-tumor treatment were enrolled retrospectively. The MRI data for these patients were divided into three groups, ie., T2WI, DWI and T2WI+ DWI, for evaluating the tumor stages. The results were compared with histopathologic findings. The sensitivity and specificity were calculated and compared with chi-square test. The nodal staging was predicted by using T2WI+ DWI. Results: The accuracy for prediction of tumor staging was 83.3%, 65.0% and 92.5% for T2WI, DWI, and T2WI+ DWI respectively. The specificity for evaluating T1 and T2 stage, and the sensitivity for evaluating T3 by DWI was significantly lower than those using T2WI and T2WI+ DWI in rectal cancers. The sensitivity for evaluation of T2 by DWI was lower than that using T2WI+ DWI (63.0% vs. 88.9%). The sensitivity for evaluation T2 and specificity for T3 by T2WI+ DWI was higher than thouse using T2WI only (88.9% vs. 51.9%, 94.0% vs. 72.0%). The accuracy for prediction of nodal staging by using T2WI+ DWI was 62.1% (72/116). Conclusions: T2WI is the key sequence for staging of rectal cancers. Although the diagnostic accuracy was not good by using DWI alone, the combination of T2WI and DWI can improve the accuracy significantly for tumor staging in rectal cancers, whereas the nodal staging was still a hard task for radiologists.

[Measurement reproducibility of parameters derived from introvoxel incoherent motion diffusion-weighted MRI imaging of rectal cancer]

Objective: To study the measurement reproducibility of parameters derived from introvoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI)-MRI of rectal cancer between- and within- radiologists. Methods: Clinical data of 34 patients with rectal cancer were prospective analyzed. Conventional MRI sequences, IVIM DWI-MRI with sixteen b values and dynamic contrast enhancement (DCE)-MRI sequences of rectum were acquired by GE 3.0-T MRI imager. The IVIM sequence images with b value=1000 sec/mm(2) were selected to measure the maximum axial section of tumor by a radiologist with 15 year-experiences in gastrointestinal cancer imaging.Two radiologists (radiologist 1 and radiologist 2 with 2 and 10 years of experience in gastrointestinal cancer imaging, respectively) independently draw a freehand region of interest (ROI) that contained the largest available tumor area on the selected section. Monoexponential apparent diffusion coefficient (ADC) and biexponential IVIM metrics maps and IVIM parameters were generated automatically by the software. The repeated measurement was performed at an interval of one week. The average values of each measurement were used for statistical analysis. ADC values and IVIM parameters obtained between- and within- radiologists were analyzed by Wilcoxon signed-rank test. Intraclass correlation coefficients (ICC) and Bland-Altaman plots were used to analyze the parameter reproducibility of two measurements between- and within- radiologists. Results: The first and second measured ADC (×10(-3)mm(2)/s), true diffusivity (D, ×10(-3)mm(2)/s), false diffusivity (D(*,) mm(2)/s) and perfusion fraction (f, %) by radiologist 1 were 0.997, 0.692, 0.043, 34.6 and 0.993, 0.691, 0.038, 32.8, respectively. The first and second measured ADC (×10(-3)mm(2)/s), D (×10(-3)mm(2)/s), D(*) (mm(2)/s), f (%) by radiologist 2 were 0.987, 0.651, 0.046, 32.8 and 0.996, 0.689、0.041, 32.7, respectively. No statistically significant differences were observed in ADC and IVIM parameters obtained between- and within- radiologists (P>0.05). The ADC values and the f values of two times were significantly correlated between- and within- radiologists. The D values were significantly correlated within a radiologist, and the correlation of D(*) values within a radiologist was significantly higher than that between radiologists. The 95% limits of agreement (LoA) of ADC values and f values were smaller than those of D values and D(*) values between- and within- radiologists. The 95% LoA of ADC values was the least, while that of D(*) values varied most.The 95% LoA of f values and D values kept steady within a radiologist, and 95% LoA of f values was slightly smaller than that of D values. The 95% LoA of IVIM parameters (ADC, D, f, D(*) values) within radiologists 2 were better than those within radiologist 1. Conclusions: The reproducibilities of ADC and f values are the best, while the reproducibility of D(*) values is relatively poorer in rectal cancer. Measurement reproducibility of parameters derived from IVIM may be improved by increasing radiologists' experiences in drawing ROI.

Application of oxaliplatin in combination with epirubicin in transcatheter arterial chemoembolization in the treatment of primary liver carcinoma

Many cases of liver carcinoma miss the opportunity of surgical treatment because of hidden onset and delayed diagnosis. In recent years, interventional treatment has gradually become a non-surgical method for treating liver carcinoma. To discuss the effects of oxaliplatin in combination with epirubicin in the treatment and its influence on prognosis, this study randomly selected 218 advanced primary liver carcinoma patients from Binzhou People’s Hospital, Binzhou, China and divided them into a control group (n=109) and an observation group (n=109). Patients in both groups were given interventional treatment. Patients in the control group were perfused with oxaliplatin, while patients in the observation group were perfused with oxaliplatin and epirubicin. The effectsat 6-month and 12-month survival rates were compared between the two groups. The results demonstrated that the overall effective rate and clinical benefit rate of the observation group were much higher than those of the control group (30.3% vs 11.9%; 79.8%; vs 44.3%) (P less than 0.05). The serum Alpha Fetal Protein (AFP) and Carcino Embryonie Antigen (CEA) levels of the observation group were much lower than those of the control group; the Karnofsky performance score of the observation group was much lower than that of the control group; the two differences had statistical significance (P less than 0.05). The 6-month survival rate of the observation group was 91.67%, higher than that of the control group (86.11%) (P>0.05). The 12-month survival rate of the observation group was 83.33%, much higher than that of the control group (61.11%) (P less than 0.05). The difference of the incidence of adverse reactions between the two groups had no statistical significance (P>0.05). Thus, it can be concluded that oxaliplatin in combination with epirubicin can improve survival quality, extend survival time, and decrease the serum AFP and CEA levels in the treatment of primary liver carcinoma, with definite effects but without aggravating toxic and side effects. Therefore, the therapy has important clinical value.

The silkworm GSTe4 is sensitive to phoxim and protects HEK293 cells against UV-induced cell apoptosis

Glutathione S-transferases (GSTs, EC 2.5.1.18) are a family of super enzymes with multiple functions that play a major role in the detoxification of endogenous and xenobiotic compounds. In our previous study, we have predicted 23 putative cytosolic GSTs in the silkworm genome using bioinformatic methods. In this study, we cloned and studied the insect-specific epsilon-class GST gene GSTe4 from the silkworm, Bombyx mori. The recombinant BmGSTe4 (Bac-BmGSTe4) was overexpressed in SF-9 cell lines, and it was found to have effective GST activity. We also found that the expression of BmGSTe4 was especially down-regulated after the silkworms were fumigated with or ingested phoxim. Moreover, BmGSTe4 protected HEK293 cells against UV-induced cell apoptosis. These results demonstrated that BmGSTe4 has GST activity, is sensitive to phoxim, and plays a role in inhibition of UV-induced cell apoptosis.

Composition and structure of microbial communities associated with different domestic sewage outfalls

The diversity of microbiota in waste waters has not been thoroughly examined, despite the potential impact of microbes on effluent quality. Wastewater microbial communities harbor pathogenic bacteria, viruses, and parasites. To study microbial communities in domestic sewage outfalls, 454 pyrosequencing technology was used to investigate the composition of microbial communities associated with municipal wastewater during different seasons sampled over the course of one year. A total of 195,103 16S rRNA gene sequences were obtained from 20 samples. The R software was used to calculate the number of indices describing the alpha diversity associated with each bacterial assemblage. In this study, the a-diversity index (H', D, J), in which higher numbers represent more diversity, was found to change with seasonal cycle. The diversity of bacterial assemblages was high in all samples, indicating that species diversity was also very high. The taxonomic composition of the assemblages varied considerably among samples, with some dominated by Proteobacteria, while others were dominated by Bacteroidetes or Firmicutes. In 2 samples, the relative prevalence of Proteobacteria exceeded 90%. α-Proteobacteria, b-proteobacteria, and g-proteobacteria represented 90% or more of all Proteobacteria. The present characterization of wastewater from five sewage outfalls indicated the presence of some pathogenic bacteria. The g-Proteobacteria in sewage wastefalls identified in this study included Enterobacteriaceae, Vibrionaceae, Pseudomonadaceae, Salmonella, Yersinia, Vibrio, and Pseudomonas aeruginosa.

SALL1, the gene mutated in Townes-Brocks syndrome, encodes a transcriptional repressor which interacts with TRF1/PIN2 and localizes to pericentromeric heterochromatin

The Townes-Brocks syndrome (TBS) is an autosomal dominantly inherited malformation syndrome presenting as an association of imperforate anus, triphalangeal and supernumerary thumbs, malformed ears and sensorineural hearing loss. Mutations in SALL1, a gene mapping to 16q12.1, were identified as a cause for TBS. To elucidate how SALL1 mutations lead to TBS, we have performed a series of functional studies with the SALL1 protein. Using epifluorescence and confocal microscopy it could be shown that a GFP-SALL1 fusion protein localizes to chromocenters and smaller heterochromatin foci in transiently transfected NIH-3T3 cells. Chromocenters consist of clustered pericentromeric heterochromatin and contain telomere sequences. Indirect immunofluorescence revealed a partial colocalization of GFP-SALL1 with M31, the mouse homolog of the Drosophila heterochromatic protein HP1. It was further demonstrated that SALL1 acts as a strong transcriptional repressor in mammalian cells. Transcriptional repression could not be relieved by the addition of the histone deacetylase inhibitor Trichostatin-A. In a yeast two-hybrid screen we identified PIN2, an isoform of telomere-repeat-binding factor 1 (TRF1), as an interaction partner of SALL1, and showed that the N-terminus of SALL1 is not necessary for the interaction with PIN2/TRF1. The interaction was confirmed in vitro in a GST-pulldown assay. The association of the developmental regulator SALL1 with heterochromatin is striking and unexpected. Our results propose an involvement of SALL1 in the regulation of higher order chromatin structures and indicate that the protein might be a component of a distinct heterochromatin-dependent silencing process. We have also provided new evidence that there is a close functional link between the centromeric and telomeric heterochromatin domains not only in Drosophila and yeast, but also in mammalian cells.

A study of the stability of generalized wave gaits

The wave gait has been observed in animal and insect walking and has been widely implemented in the control of walking machines. It has been proved that the wave gait possesses the optimum stability among all periodic gaits under the geometrical condition that R/P < or = 1, where R and P are respectively the stroke and pitch of a walking machine. Recently, based on numerical results, a generalized hexapodal wave gait was reported to be more stable than the wave gait for R/P > 1. In this paper, in order to understand more about the generalized wave gait, an analytical method is applied to study its stability in three categories of multilegged systems: quadrupeds, hexapods, and 2n-legged systems (n > or = 4). Two optimal generalized wave gaits are found for quadrupeds, and three optimal gaits are found for each of the other two categories. For all three categories, one of the optimal generalized wave gaits is the wave gait. The stability and geometrical conditions of these optimal gaits are derived and verified numerically. Furthermore, it is shown that the quadrupedal generalized wave gaits have the optimum stability among all periodic gaits with the stepping sequence 1-4-2-3.

Dual wavelength spectrophotometry as a diagnostic test of the pulp chamber contents

The purpose of this in vitro study was to determine the feasibility of using dual wavelength spectrophotometry to identify teeth with pulp chambers that are either empty, filled with fixed pulp tissue, or filled with oxygenated blood. In phase I of the experiment, a human third molar was prepared so that its pulp space could be filled with oxygenated blood and later emptied. In phase II, the lower jaw of a beagle dog was removed and placed in formalin, thereby fixing the pulps of the teeth. The pulp of the right canine was removed via an apical approach, and attachments were placed in a similar position to those on the human tooth, to allow filling and emptying of the pulp space. Cavit was placed over the exposed fixed pulp in the left canine. Ten readings, which were separated by light source and detector removal and replacement, were taken of the right canine pulp space when it was empty or filled with oxygenated blood, or the left canine pulp space when it was filled with fixed tissue. Distinct and reproducible changes were measured for pulp spaces filled with air, tissue, or oxygenated blood. In phase III, simulated pulp testing on a dog tooth model was performed. Blood was introduced into the root canal space, the chamber was rinsed with water and replaced with air, according to a predetermined code. Spectrophotometer readings were recorded. The identification of pulpal contents was correctly determined in all 20 of the predetermined conditions. The findings indicate that continuous wave spectrophotometry may become a useful pulp testing method.

Endemic goitre in central China caused by excessive iodine intake

Thyroid status was examined in children from two villages in central China where the iodine concentrations in drinking water were 462.5 and 54 micrograms/l. Goitres were present in 65% (n = 120) and 15.4% (n = 51), respectively. All children in both groups were clinically euthyroid and neurologically normal. Growth measurements and intellectual performance were similar in the two groups. Children from the high-iodine village had a lower mean serum triiodothyronine and higher serum free thyroxine and serum thyroid-stimulating hormone concentrations than the children from the control village. 2 cases of overt hypothyroidism were detected in the high-iodine village.