Entanglement of nanophotonic quantum memory nodes in a telecom network.

A key challenge in realizing practical quantum networks for long-distance quantum communication involves robust entanglement between quantum memory nodes connected by fibre optical infrastructure1-3. Here we demonstrate a two-node quantum network composed of multi-qubit registers based on silicon-vacancy (SiV) centres in nanophotonic diamond cavities integrated with a telecommunication fibre network. Remote entanglement is generated by the cavity-enhanced interactions between the electron spin qubits of the SiVs and optical photons. Serial, heralded spin-photon entangling gate operations with time-bin qubits are used for robust entanglement of separated nodes. Long-lived nuclear spin qubits are used to provide second-long entanglement storage and integrated error detection. By integrating efficient bidirectional quantum frequency conversion of photonic communication qubits to telecommunication frequencies (1,350 nm), we demonstrate the entanglement of two nuclear spin memories through 40 km spools of low-loss fibre and a 35-km long fibre loop deployed in the Boston area urban environment, representing an enabling step towards practical quantum repeaters and large-scale quantum networks.

[Best evidence summary for awake prone positioning in treating hypoxemic due to COVID-19 infection].

Objective: To retrieve, evaluate, and summarize the best evidence for the treatment of hypoxemia in patients with COVID-19 infection using the awake prone positioning, with the aim of guiding healthcare professionals in the standardized implementation of this therapy. Methods: A systematic search was conducted in databases including UpToDate, BMJ Best Practice, JBI Evidence-Based Healthcare Center, American Association of Critical-Care Nurses, Intensive Care Society, European Respiratory Society, World Health Organization website, Cochrane Library, PubMed, China National Knowledge Infrastructure (CNKI), and Wanfang. The retrieved literature was subjected to quality assessment and evidence extraction. Results: A total of ten publications were included, consisting of one thematic evidence summary, one guideline, two systematic reviews, three randomized controlled trials, and three expert consensus statements. This summary synthesizes thirty key pieces of evidence in five categories: organizational management and training, risk assessment, preparatory operations, implementation key points, and risk control. Conclusions: Awake prone positioning is beneficial for improving hypoxemia in patients with COVID-19 and is easy to implement. Medical institutions should develop nursing management systems, operational standards, and best practices for awake prone positioning based on evidence-based evidence in order to improve the quality of care management for such patients.

[The anatomic zone localization based on biparametric MRI for the prediction of the risk degree of prostate cancer].

Objective: To investigate the anatomic zone localization based on biparametric magnetic resonance imaging (bpMRI) for the prediction of the risk degree in patients with prostate cancer. Methods: A total of 92 patients with prostate cancer confirmed by radical surgery in First Affiliated Hospital, Air Force Medical University, from January 2017 to December 2021 were collected. All patients underwent bpMRI (non-enhanced scan and DWI). According to ISUP grade, those patients were divided into low-risk group [≤grade 2, n=26, aged 71 (64.0, 5.2) years] and high-risk group[≥grade 3, n=66, aged 70.5 (63.0, 74.0) years]. The interobserver consistency test for ADC values was evaluated using the intraclass correlation coefficients (ICC). The differences in total prostate specific antigen (tPSA) between the two groups were compared and the χ2 test was used to compare the differences in the risk of prostate cancer in the transitional and peripheral zone. Independent correlation factors for prostate cancer risk were analyzed by logistic regression using high and low risk of prostate cancer as dependent variables, including factors such as anatomical zone, tPSA, apparent diffusion coefficient mean (ADCmean), apparent diffusion coefficient minimum (ADCmin) and age. Receiver operating characteristic (ROC) curves were plotted to assess the efficacy of the combined models of anatomical zone, tPSA, and anatomical partitioning+tPSA for diagnosing prostate cancer risk. Results: The ICC values of the ADCmean and ADCmin between the observers were 0.906 and 0.885, respectively, with good agreement. The tPSA in the low-risk group was lower than that in the high-risk group [19.64 (10.29, 35.18) ng/ml vs 72.42 (24.79, 187.98) ng/ml; P<0.001]; the risk of prostate cancer in the peripheral zone was higher than that in the transitional zone, and the difference was statistically significant (P<0.01). Multifactorial regression showed that anatomical zones (OR=0.120, 95%CI:0.029-0.501, P=0.004) and tPSA (OR=1.059, 95%CI:1.022-1.099, P=0.002) were risk factors for prostate cancer risk. The diagnostic efficacy of the combined model (AUC=0.895, 95%CI: 0.831-0.958) was better than the predictive efficacy of the single model for both anatomical partitioning (AUC=0.717, 95%CI:0.597-0.837) and tPSA (AUC=0.801, 95%CI: 0.714-0.887) (Z=3.91, 2.47; all P<0.05). Conclusions: The malignant degree of prostate cancer in peripheral zone was higher than that in transitional zone. Combination of anatomic zone located by bpMRI and tPSA can be used to predict the risk of prostate cancer before surgery, expected to provide support for patients to develop personalized treatment strategies.

Efficient Source of Shaped Single Photons Based on an Integrated Diamond Nanophotonic System.

An efficient, scalable source of shaped single photons that can be directly integrated with optical fiber networks and quantum memories is at the heart of many protocols in quantum information science. We demonstrate a deterministic source of arbitrarily temporally shaped single-photon pulses with high efficiency [detection efficiency=14.9%] and purity [g^{(2)}(0)=0.0168] and streams of up to 11 consecutively detected single photons using a silicon-vacancy center in a highly directional fiber-integrated diamond nanophotonic cavity. Combined with previously demonstrated spin-photon entangling gates, this system enables on-demand generation of streams of correlated photons such as cluster states and could be used as a resource for robust transmission and processing of quantum information.

[The value of a nomogram based on clinical data and contrast enhanced CT radiomics in the preoperative prediction of Epstein-Barr virus-associated gastric carcinoma].

Objective: To explore the value of a nomogram based on clinical data and enhanced CT radiomics in the prediction of Epstein-Barr virus-associated gastric carcinoma(EBVaGC). Methods: The data of 136 patients, including 100 males and 36 females, aged [M (Q1, Q3)] 65 (53, 71) years, with gastric cancer confirmed by surgery and pathology were retrospectively analyzed. According to Epstein-Barr virus-encoded small RNA (EBER) in situ hybridization, those patients were divided into Epstein-Barr virus (EBV) positive group (n=32) and EBV negative group (n=104). All patients underwent multi-phase enhanced CT scanning before surgery and randomly assigned to the training group (n=95) and validation group (n=41) in a ratio of 7︰3. MaZda software was used to extract radiomics features of enhanced CT images. The intra-group correlation coefficient (ICC), variance analysis and minimum absolute shrinkage and selection algorithm (LASSO) regression were used to reduce the dimensionality of the radiomics features, and then the radiomics score (Radscore) was calculated. The nomogram model was based on combined clinical data, morphological features and Radscore. The predictive power of the nomogram was evaluated according to the area under the receiver operating characteristic curve (AUC), and the net clinical benefit of the nomogram was evaluated by the decision curve and calibration curves were drawn according to the data of the training group and the validation group to analyze the consistency of the nomogram model. Results: After selection, six optimal radiomics features were obtained, including Mean, Skewness, S(1, 0) Sum entropy, S(1, 1) Contrast, 99% percentile and S(2, 2)Angular second moment. Radscore of EBV positive group were higher than that of the EBV negative group (training group: 3.78±0.83 vs 2.80±0.98; validation group: 3.81±0.47 vs 2.94±0.95) (both P<0.05) both in the training group and validation group. The AUC of the radiomics model in training group and validation group were 0.773(95%CI:0.612-0.962)and 0.792(95%CI:0.597-0.927)respectively,and the sensitivity and specificity were 63.6% and 93.1%, 70.0% and 87.1%, respectively. The AUC of the nomogram model based on clinical data and radiomics in the training group and the validation group were 0.883(95%CI:0.644-0.984) and 0.851(95%CI:0.715-0.996), respectively. The nomogram model showed superior predictive performance (both P<0.05). Conclusion: The nomogram model based on clinical data and radiomics has better efficacy in the prediction of Epstein-Barr virus associated gastric cancer.

Changes in growth factor levels in the cerebrospinal fluid of autism patients after transplantation of human umbilical cord blood mononuclear cells and umbilical cord-derived mesenchymal stem cells.

The aim of the current study was to evaluate the levels of growth factors in the cerebrospinal fluid (CSF) of patients with autism, after transplantation of human umbilical cord blood mononuclear cells (CBMNCs) and umbilical cord-derived mesenchymal stem cells (UCMSCs). Twenty patients received two CBMNC intravenous and intrathecal infusions, each followed by two UCMSC intrathecal injections. A 2-mL sample of CSF was taken before each intrathecal injection. CSF levels of hepatocyte growth factor (HGF), brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF) and basic fibroblast growth factor (bFGF) were determined by an enzyme-linked immunosorbent assay (ELISA). All data are reported as means ± SD and were analyzed using the SPSS 10.0 software. One-way analysis of variance with post-hoc F- and Q-tests was performed for comparison. HGF, BDNF and NGF levels in the CSF were significantly increased after transplantation (P < 0.05), while bFGF levels did not change significantly. Therefore, transplantation of CBMNCs and UCMSCs could increase HGF, BDNF and NGF levels in the CSF of patients with autism.

A novel water-soluble sulfonated porphyrin fluorescence sensor for sensitive assays of H2O2 and glucose.

Water soluble porphyrins have many perfect analytical figures of merit. A water-soluble sulfonated porphyrin (H2TEHPPS) was used to build a novel platform for sensitive assays of hydrogen peroxide and glucose based on the different effects of Fe(2+) and Fe(3+) on H2TEHPPS. H2O2 or Fe(2+) alone cannot induce a fluorescence change in H2TEHPPS, but Fe(3+) can quench the fluorescence of H2TEHPPS significantly. Interestingly, glucose is oxidized to gluconolactone by GOD and generates an equivalent hydrogen peroxide, and the produced H2O2 also oxidizes Fe(2+) to Fe(3+) and causes the fluorescence quenching of H2TEHPPS. According to this, a sensitive sensor for hydrogen peroxide and glucose has been demonstrated, which can determine H2O2 and glucose in a relative simple and sensitive way. The detection limits were 1.3 × 10(-7) M and 3.2 × 10(-7) M for H2O2 and glucose, respectively. In addition, the glucose in serum samples was determined successfully using this sensing platform. It is also noteworthy that H2O2 can be released in almost all oxidations catalyzed by oxidases, which suggests that this newly proposed H2O2 probe can be readily extended to sense other oxidases and their specific substrates.

Transplantation of umbilical cord blood mononuclear cells increases levels of nerve growth factor in the cerebrospinal fluid of patients with autism.

We aimed to evaluate the levels of growth factors in the cerebrospinal fluid (CSF) of patients with autism after transplantation of umbilical cord blood mononuclear cells (CBMNCs). Fourteen subjects diagnosed with autism received transplantation of CBMNCs first through intravenous infusion, and three times subsequently through intrathecal injections. A 2-mL sample of CSF was taken before each intrathecal injection. CSF levels of nerve growth factor (NGF), vascular endothelial growth factor (VEGF), and basic fibroblast growth factor (bFGF) were determined by enzyme-linked immunosorbent assay. All data are reported as means ± SD and were analyzed using the SPSS 10.0 software. One-way analysis of variance with post-hoc F-and Q-tests were performed for comparisons. NGF levels in the CSF were significantly increased after transplantation (213.54 ± 56.38 after the third versus 28.32 ± 12.22 ng/L after the first transplantation; P < 0.05), while VEGF and bFGF levels did not change significantly. Therefore, transplantation of CBMNCs could increase NGF levels in the CSF of patients with autism.

Renal carcinomas associated with Xp11.2 translocations: are CT findings suggestive of the diagnosis?

AIM: The purpose of the present study was to summarize the computed tomography (CT) features of renal carcinomas associated with Xp11.2 translocations, and determine whether the diagnosis can be reliably deduced from imaging findings. MATERIALS AND METHODS: Radiological studies of six patients (aged from 9-29 years) with renal carcinoma associated with Xp11.2 translocations were retrospectively analysed. RESULTS: The tumours varied in size from 3.3-11 cm (mean 5.4 cm). Unenhanced CT and cortical, medullary, and pelvic-phase contrast-enhanced CT imaging was undertaken in all cases. Unenhanced CT revealed that tumours had a relatively increased radiodensity (4/6, ranged from 45-60 HU) and suggested the possibility of diffuse haemorrhage. Three of the six cases showed irregular and boundary calcification of the lesion. Contrast-enhanced CT showed relatively well demarcated tumours with heterogeneous enhancement (6/6). Prolonged enhancement of tumours might be a common sign (6/6) in Xp11.2 translocations. Three out of the six cases were combined with retroperitoneal lymph nodes metastasis. CONCLUSION: Renal carcinomas associated with Xp11.2 translocations should be considered, particularly in children and young patients, when the lesion has calcification and is hyper-dense on unenhanced CT, and has prolonged enhancement on contrast-enhanced images.

Robust multi-qubit quantum network node with integrated error detection.

Long-distance quantum communication and networking require quantum memory nodes with efficient optical interfaces and long memory times. We report the realization of an integrated two-qubit network node based on silicon-vacancy centers (SiVs) in diamond nanophotonic cavities. Our qubit register consists of the SiV electron spin acting as a communication qubit and the strongly coupled silicon-29 nuclear spin acting as a memory qubit with a quantum memory time exceeding 2 seconds. By using a highly strained SiV, we realize electron-photon entangling gates at temperatures up to 1.5 kelvin and nucleus-photon entangling gates up to 4.3 kelvin. We also demonstrate efficient error detection in nuclear spin-photon gates by using the electron spin as a flag qubit, making this platform a promising candidate for scalable quantum repeaters.

Incidence, severity, and determinants of uterine contraction pain after vaginal delivery: a prospective observational study.

BACKGROUND: Postpartum uterine contraction pain has not been studied sufficiently. We aimed to assess the incidence, intensity, and risk factors for postpartum uterine contraction pain. METHODS: Women with singleton pregnancies who delivered vaginally were enrolled in this prospective, observational, single-institution study. We determined the numerical rating scale (NRS) score (0 to 10-point) for uterine contraction pain at 6, 12, 24, and 48 h after delivery. Generalized mixed modeling was used to identify the risk factors for significant postpartum uterine contraction pain (NRS score ≥3). We compared the incidence and severity of postpartum uterine contraction pain between nulliparous and multiparous women. RESULTS: Two hundred and sixty-five nulliparous and 139 multiparous women were included. Forty-seven percent (188/404; 95% confidence interval [CI] 41.7% to 51.4%) of women presented with significant uterine contraction pain within 48 h of delivery. The generalized mixed model showed that nulliparous women had a lower risk of significant postpartum uterine contraction pain compared with multiparous women (odds ratio [OR] 0.33, 95% CI 0.17 to 0.61; P<0.001). Women with a history of dysmenorrhea had higher risk of significant postpartum uterine contraction pain (OR 1.77, 95% CI 1.12 to 2.79; P=0.014). Both nulliparous and multiparous women reported more intense uterine contraction pain while breastfeeding (P<0.001). CONCLUSIONS: Postpartum uterine contraction pain is common and severe in some women. Parity and history of dysmenorrhea are significant risk factors for significant postpartum uterine contraction pain.

Unusually thick shear-softening surface of micrometer-size metallic glasses.

The surface of glass is crucial for understanding many fundamental processes in glassy solids. A common notion is that a glass surface is a thin layer with liquid-like atomic dynamics and a thickness of a few tens of nanometers. Here, we measured the shear modulus at the surface of both millimeter-size and micrometer-size metallic glasses (MGs) through high-sensitivity torsion techniques. We found a pronounced shear-modulus softening at the surface of MGs. Compared with the bulk, the maximum decrease in the surface shear modulus (G) for the micro-scale MGs reaches ~27%, which is close to the decrease in the G upon glass transition, yet it still behaves solid-like. Strikingly, the surface thickness estimated from the shear-modulus softening is at least 400 nm, which is approximately one order of magnitude larger than that revealed from the glass dynamics. The unusually thick surface is also confirmed by measurements using X-ray nano-computed tomography, and this may account for the brittle-to-ductile transition of the MGs with size reductions. The unique and unusual properties at the surface of the micrometer-size MGs are physically related to the negative pressure effect during the thermoplastic formation process, which can dramatically reduce the density of the proximate surface region in the supercooled liquid state.

MiR-195 alleviates ulcerative colitis in rats via MAPK signaling pathway.

OBJECTIVE: To study the effect of micro ribonucleic acid (miR)-195 on the inflammatory response of ulcerative colitis (UC) model rats and to explore its regulatory mechanism, thus providing a new scheme for the clinical treatment of UC. MATERIALS AND METHODS: A rat model of UC was prepared by 2, 4, 6-trinitrobenzenesulfonic acid (TNBS)/ethanol assay, and the rats were randomly divided into Control group, Model group, and miR-195 mimic (miR-195 agomir) group. The disease activity index (DAI) in each group was observed. Hematoxylin and eosin (H&E) staining was utilized to detect the pathological changes in the rat colon tissues in each group. The levels of interleukin-6 (IL-6) and IL-1ß in the colon tissues of the rats in each group were detected by enzyme-linked immunosorbent assay (ELISA). In addition, the messenger RNA (mRNA) and protein levels of p38 mitogen-activated protein kinase (p38 MAPK) and tumor necrosis factor-alpha (TNF-α) in the colon tissues of each group of rats were examined via Reverse Transcription-Polymerase Chain Reaction (RT-PCR) and Western blotting, respectively. RESULTS: Compared with those in Control group, the rats in Model group had an increased DAI score, severely pathologically damaged colon tissues, raised levels of IL-6 and IL-1ß in the colon tissues and significantly elevated mRNA and protein levels of p38 MAPK and TNF-α. In comparison with those in Model group, the DAI score was decreased, the pathological damage to the rat colon tissues was improved, the levels of IL-6 and IL-1ß in the rat colon tissues were reduced, and the mRNA and protein levels of p38 MAPK and TNF-α were notably lowered in miR-195 agomir group. CONCLUSIONS: MiR-195 mimics can alleviate the pathological damage to the colon and inflammatory responses in UC model rats, and its mechanism may be related to the inhibition on the p38 MAPK signaling pathway.

Association Between Acid-Suppressive Agents' Use and Risk of Hepatocellular Carcinoma.

BACKGROUND: Acid-suppressive agents (ASAs), which are mostly used in patients with upper gastrointestinal diseases (UGIDs), may influence the risk of hepatocellular carcinoma (HCC). METHODS: A population-based retrospective cohort study was conducted. Patients with UGID who used ASAs and those who did not receive ASAs were identified. Patients without UGIDs were randomly selected and matched (comparison group). All groups were followed up for 6 years. A Cox proportional hazard model was used to estimate the risk of HCC among the different groups. RESULTS: Patients with UGID who used ASAs had a significantly elevated HCC risk (adjusted hazard ratio [HR] 1.53; 95% confidence interval [CI], 1.32-1.76] compared to those who did not use ASAs. Patients with UGID who used more than 540 defined daily doses of ASAs had a significantly higher risk of HCC (adjusted HR 2.04; 95% CI, 1.62-2.58). Moreover, the dose effect on HCC risk exhibited a significant increasing trend (P < .01). Furthermore, patients with UGID who did not use ASAs had a significantly elevated HCC risk (adjusted HR 1.94; 95% CI, 1.59-2.36) compared to the comparison group. CONCLUSION: The use of ASAs increased the risk of HCC in patients with UGIDs, and the effect of ASAs was dose dependent. In addition, UGIDs alone increased the risk of HCC.

Resolution of nephrotic syndrome after successful bariatric surgery in patient with biopsy-proven FSGS.

The incidence of obesity-related nephropathy (ORG) is increasing with the growing incidence of obesity. ORG is associated with morbid obesity, proteinuria and renal biopsy findings of focal global and segmental glomerulosclerosis (FSGS), which can be associated with significant renal impairment. Weight reduction is associated with improvement of ORG, however, conservative measures aiming at long-term weight reduction are difficult to achieve. Bariatric surgery is the most effective way of achieving long-term weight reduction. We present a case of ORG with nephrotic-range proteinuria and FSGS on renal biopsy. Following bariatric surgery, patient achieved successful weight reduction with significant decrease in proteinuria and stabilization of renal function.

Complete Genome Sequence Analysis and Characterization of Selected Iron Regulation Genes of Pasteurella Multocida Serotype A Strain PMTB2.1.

Although more than 100 genome sequences of Pasteurella multocida are available, comprehensive and complete genome sequence analysis is limited. This study describes the analysis of complete genome sequence and pathogenomics of P. multocida strain PMTB2.1. The genome of PMTB2.1 has 2176 genes with more than 40 coding sequences associated with iron regulation and 140 virulence genes including the complete tad locus. The tad locus includes several previously uncharacterized genes such as flp2, rcpC and tadV genes. A transposable phage resembling to Mu phages was identified in P. multocida that has not been identified in any other serotype yet. The multi-locus sequence typing analysis assigned the PMTB2.1 genome sequence as type ST101, while the comparative genome analysis showed that PMTB2.1 is closely related to other P. multocida strains with the genomic distance of less than 0.13. The expression profiling of iron regulating-genes of PMTB2.1 was characterized under iron-limited environment. Results showed significant changes in the expression profiles of iron-regulating genes (p < 0.05) whereas the highest expression of fecE gene (281 fold) at 30 min suggests utilization of the outer-membrane proteins system in iron acquisition at an early stage of growth. This study showed the phylogenomic relatedness of P. multocida and improved annotation of important genes and functional characterization of iron-regulating genes of importance to the bacterial growth.

Polycystin-1, the PKD1 gene product, is in a complex containing E-cadherin and the catenins.

Autosomal dominant polycystic kidney disease (ADPKD) is a common human genetic disease characterized by cyst formation in kidney tubules and other ductular epithelia. Cells lining the cysts have abnormalities in cell proliferation and cell polarity. The majority of ADPKD cases are caused by mutations in the PKD1 gene, which codes for polycystin-1, a large integral membrane protein of unknown function that is expressed on the plasma membrane of renal tubular epithelial cells in fetal kidneys. Because signaling from cell-cell and cell-matrix adhesion complexes regulates cell proliferation and polarity, we speculated that polycystin-1 might interact with these complexes. We show here that polycystin-1 colocalized with the cell adhesion molecules E-cadherin and alpha-, beta-, and gamma-catenin. Polycystin-1 coprecipitated with these proteins and comigrated with them on sucrose density gradients, but it did not colocalize, coprecipitate, or comigrate with focal adhesion kinase, a component of the focal adhesion. We conclude that polycystin-1 is in a complex containing E-cadherin and alpha-, beta-, and gamma-catenin. These observations raise the question of whether the defects in cell proliferation and cell polarity observed in ADPKD are mediated by E-cadherin or the catenins.

Physicochemical properties of starches and expression and activity of starch biosynthesis-related genes in sweet potatoes.

The functional properties of starches from six sweet potato varieties containing various starch components and structures were studied in an attempt to identify starch sources for industrial uses. Tainan 18 (TNN18) with high-amylose (AM) starch exhibited high setback and breakdown viscosities, high water solubility at 85°C but low swelling volume at 65°C, and high hardness and adhesiveness; in contrast, the low-AM starch of Tainung 31 (TNG31) had opposite characteristics. Seven genes related to starch biosynthesis were tested, and GBSS, SS, SBEII, ISA, and AGPase were highly expressed in TNN18 and TNG31; however, transcript levels in DBE and SBE were extremely low. GBSS and SS activity reflected the abundance of GBSS and SS mRNA in TNG31 and TNN18, and expression of AGPase, GBSS, SS, and SBE in TNN18 substantially increased content of AM. The expression and activity of DBE had a significant effect on TNG31 with increased AP content.

Studies on time-related changes of dipeptidyl peptidase during processing of Jinhua ham using response surface methodology.

Sixty experimental Jinhua hams were processed by traditional methods using green hams from local cross-bred pigs of Lanxi, Zhejiang province, PR China. Biceps femoris was sampled from five hams randomly taken after each processing stage. Potential activities of DPP I and IV in addition to the changes of some enzyme influencing factors were determined. The effects of temperature, sodium chloride content, sodium nitrate content and pH value on the activities of muscle DPP I and IV were evaluated using Response Surface Methodology (RSM) and the actual activities of muscle DPP I and IV during Jinhua ham processing were estimated. The results showed that potential activity of muscle DPP I decreased gradually from 8608.23 to 1842.06 Ug(-1) before loft-aging and then increased gradually from 1842.06 to 12196.60 Ug(-1) at the end, while that of muscle DPP IV decreased continuously and about 11% of the initial potential activity was left at the end of processing. Most of the chemical components analyzed in Biceps femoris as well as physical parameters changed greatly during processing. Temperature, sodium chloride concentration and pH value influenced DPP I and IV activities significantly. However, nitrate concentration from 0 to 50 mgkg(-1) showed little effect. By regression analysis, two quadratic regression equation models were built. The models showed that DPP I could have strong activity during Jinhua ham processing, whereas the activity of DPP IV was always very weak despite its strong potential for activity. In conclusion, muscle DPP I may be a key enzyme responsible for the generation of dipeptides in Jinhua ham processing while the effect of DPP IV was possibly very limited.

Time-related changes in cathepsin B and L activities during processing of Jinhua ham as a function of pH, salt and temperature.

Sixty experimental Jinhua hams were processed by traditional methods using green hams from local crossbred pigs of Lanxi, Zhejiang province, PR China. Biceps femoris was sampled from five hams randomly taken after each processing stage. Potential activities of cathepsin B and L were determined. The effects of temperature, salt content, pH value and nitrate content on the activities of cathepsin B and L were evaluated using response surface methodology (RSM) and the actual activities of cathepsin B and L during Jinhua ham processing were calculated. The results showed that potential activities of cathepsin B and L decreased gradually from 11332.05 to 9955.50 Ug(-1) prior salting to 1055.32-1359.90 Ug(-1) at the end of post-aging, respectively. After processing, about 9.31% original potential activity of cathepsin B and 13.66% original potential activity of cathepsin L were left. Temperature, pH value and salt content showed significant effects on cathepsin B and L activities. By stepwise regression analysis, two quadratic regression equation models were built individually for estimating cathepsin B and L activities. The models predicted that the actual activities of cathepsin B and L were less than 5% of their corresponding potential activities most of the time before half of loft-aging and about 15% and 20% during the rest processing periods. Nevertheless, cathepsin B and L retained actual activities throughout processing, especially during loft-aging and post-aging periods.