Discovery of New Isotopes ^{160}Os and ^{156}W: Revealing Enhanced Stability of the N=82 Shell Closure on the Neutron-Deficient Side

Using the fusion-evaporation reaction ^{106}Cd(^{58}Ni,4n)^{160}Os and the gas-filled recoil separator SHANS, two new isotopes _{76}^{160}Os and _{74}^{156}W have been identified. The α decay of ^{160}Os, measured with an α-particle energy of 7080(26) keV and a half-life of 201_{-37}^{+58}  μs, is assigned to originate from the ground state. The daughter nucleus ^{156}W is a β^{+} emitter with a half-life of 291_{-61}^{+86}  ms. The newly measured α-decay data allow us to derive α-decay reduced widths (δ^{2}) for the N=84 isotones up to osmium (Z=76), which are found to decrease with increasing atomic number above Z=68. The reduction of δ^{2} is interpreted as evidence for the strengthening of the N=82 shell closure toward the proton drip line, supported by the increase of the neutron-shell gaps predicted in theoretical models.

Expression of polyphenol oxidase of Litopenaeus vannamei and its characterization

Polyphenol oxidase (PPO) plays a critical role in decrement of shrimp quality. To obtain active PPO and elucidate its enzymatic properties, PPO from Litopenaeus vannamei (Lv-PPO) was cloned, expressed in E. coli and purified by affinity column chromatography. The Lv-PPO gene was 2076 bp in length encoding 691 amino acids. The recombinant Lv-PPO (rLv-PPO) with a molecular mass of ∼85.0 kDa was successfully expressed and its sequence was verified by LC-MS/MS. rLv-PPO was biologically active with an optimal temperature of 40℃ and an optimal pH of 6.0. Metal ions Cu2+ and Zn2+ altered the activity of rLv-PPO by influencing its secondary and tertiary structures. rLv-PPO showed catalytic activity towards l-Dopa and catechol. A specific polyclonal antibody against rLv-PPO was prepared. Western blot analysis revealed that PPO levels were highest in hemolymph, followed by telson, carapace, and eyestalk. Expression of rLv-PPO will assist future studies on the mechanism in shrimp melanosis.

Properties of Pacific white shrimp (Litopenaeus vannamei) collagen and its degradation by endogenous proteinases during cold storage

Many factors are responsible for the diminished quality of shrimp during cold storage, while the role of collagen has rarely been studied. This study therefore investigated the relationship between collagen degradation and changes of textural properties of Pacific white shrimp, and its hydrolysis by endogenous proteinases. The textural properties of shrimp decreased gradually along with disruption of shrimp muscle tissues, and the chewiness property of shrimp muscle showed a linear relationship with collagen contents in muscle during 6-day-storage at 4 °C. Pepsin-solubilized collagen in shrimp muscle consisted of one α1 chain and two α2 chains, revealing a typical tripeptide sequence (i.e., Gly-X-Y) in their molecules. In addition, collagen could be hydrolyzed by crude endogenous proteinases extracted from shrimp hepatopancreas, and serine proteinase plays a critical role in the process. These findings strongly suggested that the quality reduction of shrimp during cold storage is closely associated with collagen degradation.

Research Progresses and Applications of Fluorescent Protein Antibodies: A Review Focusing on Nanobodies

Since the discovery of fluorescent proteins (FPs), their rich fluorescence spectra and photochemical properties have promoted widespread biological research applications. FPs can be classified into green fluorescent protein (GFP) and its derivates, red fluorescent protein (RFP) and its derivates, and near-infrared FPs. With the continuous development of FPs, antibodies targeting FPs have emerged. The antibody, a class of immunoglobulin, is the main component of humoral immunity that explicitly recognizes and binds antigens. Monoclonal antibody, originating from a single B cell, has been widely applied in immunoassay, in vitro diagnostics, and drug development. The nanobody is a new type of antibody entirely composed of the variable domain of a heavy-chain antibody. Compared with conventional antibodies, these small and stable nanobodies can be expressed and functional in living cells. In addition, they can easily access grooves, seams, or hidden antigenic epitopes on the surface of the target. This review provides an overview of various FPs, the research progress of their antibodies, particularly nanobodies, and advanced applications of nanobodies targeting FPs. This review will be helpful for further research on nanobodies targeting FPs, making FPs more valuable in biological research.

Involvement of MMP-9 in collagen degradation of sea bass (Lateolabrax japonicus): Cloning, expression, and characterization

Disintegration of intramuscular connective tissue is responsible for postmortem tenderization of fish muscles during chilled storage. Matrix metalloproteinase-9 (MMP-9) was reported to be involved in this process, whereas the mechanism has not been revealed. In the present study, purified type I and V collagens from the connective tissues of sea bass (Lateolabrax japonicus) muscles were first prepared. These two kinds of collagens comprise three polypeptide chains (α), forming a typical triple-helical domain as determined by circular dichroism. The complete coding region of MMP-9 containing an open reading frame of 2070 bp encoding 689 amino acid residues was then cloned. The recombinant MMP-9 catalytic domain (rcMMP-9) was expressed in Escherichia coli and exhibited high hydrolyzing activity toward gelatin. Besides, rcMMP-9 was effective in degrading type V collagen rather than type I collagen at 4°C. The enzymatic activity of rcMMP-9 was highly pH-dependent, and its enzymatic activity under neutral and basic conditions was higher than that under acidic conditions. Metal ion Ca²⁺ was necessary for the maintenance of rcMMP-9 activity, whereas Zn²⁺ inhibited its activity. Our present study indicated that MMP-9 is responsible for the disintegration of intramuscular connective tissues by cleaving type V collagen during postmortem tenderization of fish muscle. PRACTICAL APPLICATION: Elucidation the involvement of MMP-9 in collagen degradation will deliver a reference for the prevention of muscular protein decomposition during chilled storage of fish fillets.

Relationships of Matrix Metalloproteinase 1 and a Tissue Inhibitor of Metalloproteinase to Collagen Metabolism in Haliotis discus hannai

In response to physical, chemical, and/or biological stimuli, considerable tissue self-degradation occurs in abalone, causing severe post-harvest quality loss. During this process, the extracellular matrix (ECM) is greatly degraded by endogenous proteases. The main component of the ECM is collagen, primarily type I collagen. Although the activity of matrix metalloproteinases (MMPs), which can specifically degrade collagen, is precisely regulated by tissue inhibitors of MPs (TIMPs), indicating that MMPs and TIMPs play crucial roles in the regulation of tissue self-degradation, few studies have reported the interaction between MMPs and TIMPs. In this study, we reveal collagenases to participate in postmortem tissue self-degradation of Haliotis discus hannai by degrading type I collagen. The recombinant MMP-1 catalytic domain (rMMP1c) of abalone with high purity and enzyme activity is expressed using a prokaryotic expression system. The optimum temperature and pH for rMMP1c are 37 °C and 7.0, respectively. The thermal denaturation temperature of rMMP1c is 67.0 ± 0.9 °C. Ethylenediamine tetraacetic acid (EDTA) and 1,10-phenanthroline can completely inhibit rMMP1c activity, while Ba²⁺, Ca²⁺, and Mg²⁺ can significantly elevate it. TIMP is also expressed using HEK 293F cells. Recombinant TIMP (rTIMP) shows good inhibitory activity toward rMMP1c. Inhibition kinetics analyses reveal rTIMP to be a competitive inhibitor of rMMP1c. Biolayer interferometry reveals that rTIMP can effectively bind with rMMP1c, with an equilibrium dissociation constant value of 263 nM. rMMP1c effectively degrades type I collagen γ-β-α chains in turn, and rTIMP can significantly inhibit rMMP1c degradation activity. These results provide a theoretical basis for the study of MMP and TIMP interaction and elucidate the possible mechanism for abalone tissue self-degradation.

Effects of partial substitution of NaCl on myofibrillar protein properties from pearl mussel Hyriopsis cumingii muscle: Structural characteristics and aggregation behaviors

The effects of NaCl and its partial substitutes (KCl, MgCl₂ and CaCl₂) on solubility, structural characteristics and aggregation behaviors of myofibrillar protein (MP) from pearl mussel muscle were investigated and compared. MP at 0.6 M NaCl was beneficial to protein unfolding and showed excellent potential functional properties. When NaCl was substituted in low level, MPs also showed good solubility and ordered microstructure as well as NaCl, especially MgCl₂ and CaCl₂, due to the unfolding of α-helical structures and subsequently exposed tyrosine residues and hydrophobic groups. However, the obviously increased disulfide bonds and hydrophobic interactions in high substitution level indicated the excessive non-sodium salts had negative effects on molecular rearrangement, leading to irregular and overly tight of microstructure. Thus, NaCl partially substituted by KCl, MgCl₂ and CaCl₂ in low substitution level is promising to improve functional properties of MP in low-sodium meat products.

[Re-examination of malaria diagnosis in Hubei Provincial Malaria Diagnostic Reference Laboratory from 2017 to 2019]

OBJECTIVE

To analyze the re-examination results of malaria cases captured from the National Notifiable Communicable Disease Reporting System in Hubei Provincial Malaria Diagnostic Reference Laboratory from 2017 to 2019, so as to pro- vide the scientific evidence for improving the malaria control capability in the province.

METHODS

Microscopy and nested PCR assay were performed to re-examine the diagnosis of malaria cases registered in the National Notifiable Communicable Disease Reporting System in Hubei Provincial Malaria Diagnostic Reference Laboratory from 2017 to 2019, and the coincidences of ma- laria diagnosis and malaria parasite species were evaluated.

RESULTS

A total of 410 malaria cases were reported in Hubei Province from 2017 to 2019 according to the data retrieved from the National Notifiable Communicable Disease Reporting System. Among the 407 samples re-examined by Hubei Provincial Malaria Diagnostic Reference Laboratory from 2017 to 2019, the diag- nosis 374 malaria cases were confirmed, with an overall coincidence of 91.89% (374/407) for malaria diagnosis and 89.04% (333/374) for parasite species identification. The coincidence rates of malaria diagnosis and parasite species identification were 50.00% to 100.00% and 66.67% to 100.00% in 16 cities (prefectures) of Hubei Province during the re-examinations, which both varied in regions (χ² = 40.46 and 42.30, both P values < 0.01). The coincidence rates of Plasmodium falciparum, P. vivax, P. malariae and P. ovale identification were 95.80%, 100.00%, 58.33% and 51.92% during the re-examinations, respectively (χ² = 76.66, P < 0.01). The consistency rate between microscopic and nested PCR results was 89.83% (362/403).

CONCLUSIONS

The overall diagnostic quality of malaria is high in medical institutions at all levels in Hubei Province; however, the diagnostic capability of malaria remains to be improved in some regions.

[An epidemiological survey on clinical features, self-management and cognitive level of elderly asthmatics in China]

Objective: To investigate the prevalence of asthma among the elderly people in China and to analyze the clinical features, self-management and cognitive level of elderly asthma patients. Methods: According to the multi-stage random cluster sampling methods, a total of 164 215 subjects were visited by a questionnaire in the last epidemiology survey from eight provinces (Beijing, Shanghai, Guangdong, Liaoning, Henan, Shanxi, Jiangsu, Sichuan provinces) and seven regions (north, northeast, southern china, east, south, southwest and northwest) in China from February 2010 to August 2012. 2 034 were diagnosed as asthma. The elderly patients aged ≥65 years were selected from the 2 034 asthma patients. The clinical characteristics, comorbidities, the status of asthma control and self-management and insights of the disease in elderly asthma patients were analyzed. Results: Among the 2 034 asthma patients, 584 (28.7%) were elderly asthmatics aged ≥65 years old and 1 450 (71.3%) were<65 years old. In the elderly asthma group, Early-onset asthma accounted for 439 (75.2%) and 145 (24.8%) were late-onset. The common clinical manifestations of elderly asthma patients were: chest distress 395 (67.6%), wheezing 304 (52.1%), cough 298 (51.0%). Common comorbidities of elderly asthmatics were: chronic obstructive pulmonary disease 144 (24.7%), allergic rhinitis 122(20.9%), gastroesopheal reflux disease (GERD) 114(19.5%), allergic conjunctivitis 86 (14.7%), eczema 82 (14.0%), chronic bronchitis 76 (13.0%). The Asthma Control Test (ACT) scores of elderly asthmatics and non-elderly asthmatics were (18.5±3.2) and (21.7±3.4) respectively. There was a significant difference between the two groups (P=0.042). Of the elderly asthmatics, only 13 (2.2%) patients monitored daily using a peak flow meter. 93 (15.9%) patients aware that asthma was characterized by chronic airway inflammation. 64 (11.0%) asthmatics understood that the treatment goal. Conclusions: The clinical manifestations of elderly asthmatics are atypical, especially paroxysmal wheezing. Asthma in elderly people causes more comorbidities and mortality. The self-management and cognitive level of patients with asthma needs to be improved.

[A survey on clinical characteristics and risk factors of severe asthma in China]

Objective: To investigate the clinical characteristics and risk factors of severe bronchial asthma in Chinese people over 14 years old. Methods: According to the multi-stage random cluster sampling methods, a total of 164 215 subjects were visited by a questionnaire in the epidemiology survey from eight provinces (Beijing, Shanghai, Guangdong, Liaoning, Henan, Shanxi, Jiangsu, Sichuan provinces) located in seven regions (north, northeast, east, central China, south, southwest and northwest) of China from February 2010 to August 2012. A total of 2 034 were diagnosed as asthma. The clinical characteristics and related risk factors of patients with severe asthma in China were analyzed. Results: Among all asthma patients, 560 were newly diagnosed, accounting for 27.5% (560/2 034) and the percentage of previously confirmed patients was 72.5% (1 474/2 034). A total of 145 were eligible for severe asthma, accounting for 9.8% (145/1 474) of previously confirmed asthmatics and 7.1% (145/2 034) of all asthmatics. 83.5% (121/145) severe asthmatics had at least one trigger factor. Correlation analysis showed that the risk factors of severe asthma were: smoking (OR=1.543, 95%CI: 1.250-1.814), obesity (OR=2.186, 95%CI: 1.972-2.354), petting (OR=2.135, 95%CI: 1.904-2.283), combined with allergic rhinitis (OR=3.456, 95%CI: 2.721-4.326), gastroesophageal reflux disease (OR=1.842, 95%CI: 1.682-2.140), bronchiectasis (OR=1.665, 95%CI: 1.347-1.912) or chronic obstructive pulmonary disease (OR=1.312, 95%CI: 1.171-1.694). Conclusions: The most common comorbidities in severe asthmatics in China are allergic rhinitis and gastroesophageal reflux disease. The risk factors of severe asthma include obesity, allergic rhinitis, gastroesophageal reflux disease, chronic obstructive pulmonary disease, bronchiectasis, smoking and petting.

The anti-diarrhea activity of red algae-originated sulphated polysaccharides on ETEC-K88 infected mice

Polysaccharides from red algae Porphyra haitanensis and Gracilaria lemaneiformis possess various bioactive functions, however, their anti-diarrhea activity remains incompletely defined. In the current study, sulphated polysaccharides were extracted by high pressure treatment plus ethanol precipitation from these two algae, and named PHSP_(hp) and GLSP_(hp), respectively. PHSP_(hp) and GLSP_(hp) showed decreased viscosity and molecular weight. Meanwhile, they have a certain immunomodulatory effect on wound healing and migration of RAW264.7 cells. Moreover, they significantly increased the secretion of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). A BALB/c model infected by enterotoxigenic Escherichia coli (ETEC)-K88 was also established to evaluate the anti-diarrhea activity of PHSP_(hp) and GLSP_(hp). The results showed that PHSP_(hp) and GLSP_(hp) were able to alleviate mice diarrhea symptoms. Meanwhile, they inhibited the release of pro-inflammatory cytokines and suppressed the secretion of immunoglobulin A via reducing the population of B cells. In addition, the nitroblue tetrazolium levels of mouse serum were decreased. Taken together, PHSP_(hp) and GLSP_(hp) alleviated the inflammatory response of ETEC-K88-induced diarrhea through both specific and non-specific immunity. Sulphated polysaccharides from red algae may be used as functional food components for remitting diarrhea.

Polysaccharides from red algae Porphyra haitanensis and Gracilaria lemaneiformis possess various bioactive functions, however, their anti-diarrhea activity remains incompletely defined.

Production, optimisation and characterisation of angiotensin converting enzyme inhibitory peptides from sea cucumber (Stichopus japonicus) gonad

The purification, characterization, and molecular docking study of a novel ACE inhibitory peptide (NAPHMR) derived from sea cucumber gonad hydrolysates.

[The relationship between smoking status and epidermiology of asthma in people aged over 14 years in China]

Objective: To study the relationship between bronchial asthma and smoking status in Chinese people. Methods: Asthma epidemiological survey and stratified-cluster-random method survey were performed in residents over 14 years in 8 provinces (cities) of China from February 2010 to August 2012. Asthma was diagnosed based upon case history, clinical signs and lung function test. Smoking status was investigated by questionnaire. Results: Sampling population was 180 099 and 164 215 were valid. A total of 2 034 subjects were diagnosed as asthma including 79 692 men and 84 523 women. The overall prevalence rate of asthma was 1.24% (2 034/164 215). Smokers were 23.8% (39 137/164 215) in the whole population. Smokers were 34.5% (702/2 034) in asthmatic patients, compared with 23.7% (38 435/162 181) in no-asthmatic population. The incidence of asthma was 1.79% and 1.06% in smokers and non-smokers respectively (P<0.001), suggesting that OR of smoking was 1.70 (95% CI 1.55-1.86, P<0.001). According to asthma control test (ACT) score, the level of asthma control in non smoking group was higher than that in smoking group(43.2% vs 35.3%). The times of hospitalization due to acute exacerbations(0.51 vs 0.41 events/person/year), total hospitalization rate(27.35% vs 20.12%), annual emergency room visits (0.80 vs 0.60 events/person/year) and emergency room visit rate (31.77% vs 24.47%) were all much higher in smoking asthmatic patients than those in non smoking asthmatic patients, indicating that the level of asthma control in smoking patients was significantly worse than in non smoking patients. Conclusions: The smoking rate in Chinese people over 14 years is still high. The prevalence rate of asthma in smokers is significantly higher than that of non-smokers. The level of asthma control in smokers is significantly worse than that in non smokers.

Cloning, Expression, and the Effects of Processing on Sarcoplasmic-Calcium-Binding Protein: An Important Allergen in Mud Crab

Shellfish allergy is a prevalent, long-lasting disorder usually persisting throughout life. However, the allergen information is incomprehensive in crab. This study aimed to identify a novel allergen in crab, show its potential in diagnosis and reduce the allergenicity by food processing. A 21-kDa protein was purified from Scylla paramamosain and confirmed as sarcoplasmic calcium binding protein (SCP) by matrix-assisted laser desorption ionization-time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF-MS). Total RNA was isolated from crab muscle, and a rapid amplification of cDNA was performed to obtain an ORF of 579 bp that coded for 193 amino acid residues. According to the results of circular dichroism analysis and ELISA assay, the recombinant SCP (rSCP) expressed in Escherichia coli showed similar physicochemical and immunoreactive properties to native SCP (nSCP). Additionally, the extensive cross reactivity of SCP among different species and the bidirectional IgE cross-reactivity between nSCP and rSCP were detected by iELISA. The allergenicity of rSCP was reduced via Maillard reaction or enzymatic cross-linking reaction, which was confirmed by the results of scanning electron microscopy, dot blot, and digestion assay. A straightforward and reproducible way was developed to obtain high yields of rSCP that maintains structural integrity and full IgE reactivity, which could compensate the low specific IgE-titers of most patient sera for future diagnosis. Furthermore, the Maillard reaction and enzymatic cross-linking reaction were effective approaches for the production of hypoallergenic seafood.

Allergenicity and Oral Tolerance of Enzymatic Cross-Linked Tropomyosin Evaluated Using Cell and Mouse Models

The enzymatic cross-linking of proteins to form high-molecular-weight compounds may alter their sensitization potential. The IgG-/IgE-binding activity, digestibility, allergenicity, and oral tolerance of cross-linked tropomyosin with tyrosinase (CTC) or horseradish peroxidase (CHP) were investigated. ELISA results demonstrated CTC or CHP reduced its IgE-binding activity by 34.5 ± 1.8 and 63.5 ± 0.6%, respectively. Compared with native tropomyosin or CTC, CHP was more easily digested into small fragments; CHP decreased the degranulation of RBL-2H3 cells and increased endocytosis by dendritic cells. CHP can induce oral tolerance and reduce allergenicity in mice by decreasing IgE and IgG1 levels in serum, the production of T-cell cytokines, and the percentage composition of dendritic cells. These findings demonstrate CHP has more potential of reducing the allergenicity than CTC via influencing the morphology of protein, changing the original method of antigen presentation, modulating the Th1/Th2 immunobalance, and inducing the oral tolerance of the allergen tropomyosin.

Preparation, characterisation and use for antioxidant oligosaccharides of a cellulase from abalone (Haliotis discus hannai) viscera

BACKGROUND

In China, abalone (Haliotis discus hannai) production is growing annually. During industrial processing, the viscera, which are abundant of cellulase, are usually discarded or processed into low-value feedstuff. Thus, it is of interest to obtain cellulase from abalone viscera and investigate its application for preparation of functional oligosaccharides.

RESULTS

A cellulase was purified from the hepatopancreas of abalone by ammonium sulfate precipitation and two-steps column chromatography. The molecular weight of the cellulase was 45 kDa on SDS-PAGE. Peptide mass fingerprinting analysis yielded 103 amino acid residues, which were identical to cellulases from other species of abalone. Substrate specificity analysis indicated that the cellulase is an endo-1,4-β-glucanase. Hydrolysis of seaweed Porphyra haitanensis polysaccharides by the enzyme produced oligosaccharides with degree of polymerisation of two to four, whose monosaccharide composition was 58% galactose, 4% glucose and 38% xylose. The oligosaccharides revealed 2,2'-diphenyl-1-picrylhydrazyl free radical as well as hydrogen peroxide scavenging activity.

CONCLUSION

It is feasible and meaningful to utilise cellulase from the viscera of abalone for preparation of functional oligosaccharides. © 2015 Society of Chemical Industry.

Mung bean trypsin inhibitor is effective in suppressing the degradation of myofibrillar proteins in the skeletal muscle of blue scad (Decapterus maruadsi)

Mung bean trypsin inhibitor (MBTI) of the Bowman-Birk family was purified to homogeneity with a molecular mass of approximately 9 kDa on tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and 8887.25 Da as determined by matrix-assisted laser desorption/ionization-quadrupole ion trap-time-of-flight mass spectrometry (MALDI-QIT-TOF MS). Using blue scad myofibrillar proteins as targets, it was found that, in the absence of MBTI, proteolysis of myofibrillar proteins, especially myosin heavy chain (MHC), could be identified after incubation at 55 °C for 2 h, while in the presence of MBTI, with a final concentration of 25 ng/mL, proteolysis of these proteins was greatly suppressed even after incubation for 3 h. Although cysteine proteinase inhibitor E-64 was also effective in preventing protein degradation, inhibitors for metallo- and asparatic proteinases did not reveal obvious inhibitory effects. Our present results strongly suggested that the naturally occurring legume bean seed protein MBTI can be used as an effective additive in preventing marine fish blue scad surimi gel softening, which is quite possibly caused by myofibril-bound serine proteinase (MBSP).

Identification of an aminopeptidase from the skeletal muscle of grass carp (Ctenopharyngodon idellus)

Aminopeptidases play important roles in turnover of proteins, metabolism of hormones and neurotransmission, cell maturation and immunological regulations. In the present study, an aminopeptidase was purified to homogeneity from the skeletal muscle of grass carp by ammonium sulfate fractionation and sequential chromatographic steps, including DEAE-Sephacel, Sephacryl S-200, hydroxyapatite and Phenyl-Sepharose. The purified enzyme revealed a molecular mass of approximately 105 kDa both on SDS-PAGE and on gel filtration of Superdex 200. The enzymatic activity toward synthetic substrates was optimal at 40°C and pH 7.0-7.5. Metal-chelating agents such as EDTA and EGTA effectively inhibited the enzyme activity while inhibitors to serine, asparatic and cysteine proteinases did not show much effect, suggesting its belonging to metalloproteinase family. A specific aminopeptidase inhibitor bestatin was most effective in suppressing the enzymatic activity and performed in a competitive fashion. The enzymatic activity was slightly enhanced by metal ions of Mg2+ and Mn2+ while inhibited to different extents by Co2+, Cu2+, Zn2+ and Ca2+. Sulfhydryl reagent was necessary to maintain its activity. Purified enzyme demonstrated amidolytic activity most effectively against synthetic aminopeptidase substrate Leu-methylcoumarylamide (MCA) while N-terminal-blocked substrates and myofibrillar proteins were not hydrolyzed. The enzyme purified in the present study was quite possibly a leucine aminopeptidase (LAP) and functions during muscular protein metabolism.

Biochemical characterization of chymotrypsins from the hepatopancreas of Japanese sea bass (Lateolabrax japonicus)

Two chymotrypsins (chymotrypsins A and B) have been purified to homogeneity from the hepatopancreas of Japanese sea bass ( Lateolabrax japonicus ) by ammonium sulfate fractionation and chromatographies on DEAE-Sepharose and Phenyl-Sepharose. Two-dimensional electrophoresis (2-DE) analysis revealed that the molecular masses of chymotrypsins A and B were approximately 27.0 and 27.5 kDa, respectively. Their respective isoelectric points were 8.0 and 7.0. Purified chymotrypsins also revealed a single band on native-PAGE, whereas their mobilities were quite different. Optimum temperature and pH of chymotrypsins A and B were 45 degrees C and 8.0, respectively. Both enzymes were strongly inhibited by chymostatin, phenylmethanesulfonyl fluoride (PMSF), and Pefabloc SC, but slightly inhibited by metalloproteinase inhibitor of 1,10-phenanthroline and EDTA. Using Suc-Leu-Leu-Val-Tyr-MCA as substrate, apparent K(m) values of chymotrypsins A and B were 0.8 and 1.1 microM and k(cat) values were 2.7 and 2.0 s(-1), respectively. The N-terminal amino acid sequences of chymotrypsins A and B were determined to the 21st and 18th residues, respectively, and were identical. These sequences exhibited high identities to chymotrypsins from other animals. The digestive effect of the two chymotrypsins on myofibrillar proteins indicated their effectiveness in the degradation of food proteins.

Purification and characterization of parvalbumins from silver carp (Hypophthalmichthy molitrix)

BACKGROUND

As the largest producer and consumer of freshwater fish in the world, many people suffer from allergy for consuming freshwater fish in China. However, the allergen profiles of freshwater fish are rarely known.

RESULTS

Parvalbumins (PVs) from the white muscle of silver carp (Hypophthalmichthy molitrix) were purified by ammonium sulfate fractionation and column chromatography including DEAE-Sepharose and Superdex 75. Three PV isoforms-PV-I, PV-II, and PV-III-were obtained and their molecular masses as estimated by tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis were 12, 11, and 14 kDa, respectively. All the PVs could be detected by anti-frog PV monoclonal antibody. PV-I and PV-II were quite possibly glycoproteins, while PV-III was not glycosylated, as analyzed by periodic acid-Schiff (PAS) staining. Thermal stability revealed that PV-I and PV-II easily formed polymers, while these proteins were stable in a pH range of 4.0-10.0. A PV gene encoding 110 amino acid residues was cloned and it revealed high identity with PVs from other species of fish.

CONCLUSION

Three isotypes of PV were purified to homogeneity and one distinct PV gene was cloned in silver carp white muscle.

Study on pepsinogens and pepsins from snakehead (Channa argus)

Three pepsinogens (PG1, PG2, and PG3) were highly purified from the stomach of freshwater fish snakehead (Channa argus) by ammonium sulfate fractionation, anion exchange, and gel filtration. Two-dimensional gel electrophoresis and native-PAGE analysis revealed that their molecular masses were 37, 38, and 36 kDa and their isoelectric points 4.8, 4.4, 4.0, respectively. All of the pepsinogens converted into their active form pepsins under pH 2.0 by one-step pathway or stepwise pathway. The three pepsins showed maximal activity at pH 3.0, 3.5, and 3.0 with optimum temperature at 45, 40, and 40 degrees C, respectively, using hemoglobin as substrate. All of the pepsins were completely inhibited by pepstatin A, a typical aspartic proteinase inhibitor. The N-terminal amino acid sequences of the three pepsinogens were determined to the 34th, 25th, and 28th amino acid residues, respectively. Western blot analysis of the three PGs exhibited different immunological reactions.

Glucose-6-phosphate isomerase is an endogenous inhibitor to myofibril-bound serine proteinase of crucian carp (Carassius auratus)

Glucose-6-phosphate isomerase (GPI) was purified to homogeneity from the skeletal muscle of crucian carp ( Carassius auratus ) by ammonium sulfate fractionation, column chromatographies of Q-Sepharose, SP-Sepharose, and Superdex 200 with a yield of 8.0%, and purification folds of 468. The molecular mass of GPI was 120 kDa as estimated by gel filtration, while on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), two subunits (55 and 65 kDa) were identified, suggesting that it is a heterodimer. Interestingly, GPI revealed specific inhibitory activity toward a myofibril-bound serine proteinase (MBSP) from crucian carp, while no inhibitory activity was identified toward other serine proteinases, such as white croaker MBSP and crucian carp trypsin. Kinetic analysis showed that GPI is a competitive inhibitor toward MBSP, and the K(i) was 0.32 microM. Our present results indicated that the multifunctional protein GPI is an endogenous inhibitor to MBSP and may play a significant role in the regulation of muscular protein metabolism in vivo.

Assessing the adequacy of endoscopically tied knots: a functional approach

BACKGROUND AND STUDY AIMS

Endoscopic intracorporeal knots have potentially enormous applications in endoscopic surgery. We describe a method for testing the security of various types of endoscopically tied knots using a vessel perfusion manometer system.

METHODS

A 4-cm segment of porcine splenic artery was placed on the mucosal surface of a pig stomach. The two ends of the vessel were brought out through the gastric wall and connected to a two-way manometer. One end was also joined to a pressure infusion bag. The stomach was mounted in an Erlangen training model. A long 3/0 nylon thread, previously introduced into the submucosal layer of the stomach and encircling the vessel, was brought out from the mouth. Three-throw square knots, Mayo knots, "surgeon's" knots and five-throw square knots were tied and pushed into place using a cap attached to a gastroscope. The pressure at the two ends of the artery was compared. If the pressure could be increased to over 200 mm Hg at one end without a change in the other, the knot was considered secure.

RESULTS

Each type of knot was tested 12 times under endoscopic vision. The range for mean knotting time was 3.4 - 4.5 minutes. Five-throw knots took significantly longer to tie than three-throw knots (P < 0.005). There was one loose knot in each of the three-throw and Mayo groups, and three each in the "surgeon's" and five-throw groups (P > 0.05).

CONCLUSIONS

This system is a reliable model for testing intracorporeal knots tied endoscopically. A three-half-hitches square knot with 3/0 nylon, tied using a flexible endoscope and knot-tightening cap, can withstand pressure up to 200 mm Hg.

Transoral obesity surgery: endoluminal gastroplasty with an endoscopic suture device

BACKGROUND AND STUDY AIMS

Surgical creation of a small gastric pouch with a restricted outlet is a well-established option for the treatment of morbid obesity. This report describes initial experience with endoscopic transoral stomach partition using a newly designed suturing apparatus.

MATERIALS AND METHODS

A fresh porcine stomach was placed in the Erlangen model. A prototype suture device, incorporating a curved needle and an intracorporeal tightening mechanism, was used in this procedure. A long fishing line was first introduced into the stomach, with the two ends left outside. The suturing device, premounted outside a standard gastroscope, was inserted into the stomach and delivered several stitches attaching the fishing line to both the anterior and posterior walls along the line for the stomach to be partitioned. Five throws of half-hitches were tied onto the fishing line extracorporeally and separately pushed into place, creating a gastric pouch just below the esophagogastric junction. A flexible sheath of 8 cm long was then put on one side of the fishing line and pushed into the stomach. Additional extracorporeal knots were tied on the fishing line, forming a restrictive ring at the outlet of the pouch. The ring was then anchored to the stomach wall with similar endosutures.

RESULTS

The proximal gastric pouch, with an estimated volume of approximately 100 ml, was successfully created with a restrictive band at its outlet. All of the stitches were securely sutured, with consistent penetration of the muscular layer of the stomach wall.

CONCLUSIONS

In a bench model, it is technically possible to accomplish transoral gastroplasty endoscopically with an intraluminal suturing device. Further live animal studies will be needed in order to confirm the efficacy and safety of this procedure before clinical application.

Purification of natural antikeratin autoantibodies from normal human serum and their effect on human keratinocytes cultured in vitro

BACKGROUND

Antikeratin (AK) autoantibodies, circulating antibodies against epidermal keratins, have been detected in all normal human sera. However, direct evidence on the biological significance of AK autoantibodies is still lacking.

OBJECTIVES

To purify AK autoantibodies from human serum and to make a preliminary study of their biological effects on human keratinocytes.

METHODS

We first extracted keratin polypeptides from human stratum corneum and analysed their purity using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Next, a keratin affinity column was prepared with the extracted keratins, and AK autoantibodies were purified from pooled normal human serum. Antibodies obtained were identified with SDS-PAGE, enzyme-linked immunosorbent assay, immunoperoxidase staining, immunoelectron microscopy and Western blotting. The biological effect of AK autoantibodies on cultured human keratinocytes was studied using a DNA synthesis assay, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric determination and cell cycle analysis.

RESULTS

On average, 1.83 +/- 0.24 mg of antibodies could be purified from 10 mL of pooled human serum. High-titre IgG (about 1 : 70) and low-titre IgM (about 1 : 30) AK autoantibodies were obtained. The DNA synthesis assay and MTT colorimetric determination demonstrated that AK autoantibodies have a significant dose-dependent inhibitory effect on cultured keratinocytes. Correlation coefficients in the two experiments were - 0.583 and - 0.797, respectively. Cell cycle analysis indicated that a small dose of AK autoantibodies leads to inhibition of proliferation of cultured keratinocytes, whereas a large dose of AK autoantibodies causes a visible hypodiploid peak, suggesting apoptosis of keratinocytes.

CONCLUSIONS

The present research lays a solid foundation for further investigation into the biological significance of natural AK autoantibodies.

Gastrointestinal absorption of plutonium by the Marshall Islanders

The gastrointestinal absorption constant (f1) is a critical parameter in assessing systemic uptake following the ingestion of a radioactive material and in monitoring such intakes. This study addresses the latter, particularly for plutonium, and from environmental measurements derives an f1 value of 4 x 10(-4) for the Marshallese population. The uncertainty associated with the methodology and measurements used in this f1 value assessment is evaluated. This evaluation takes into account the results from 24-h urine samples and the particular lifestyle of the Marshallese. Plutonium intake resulting from soil consumption is a primary parameter in this evaluation; for this study, it was assumed to be 500 mg d(-1). The f1 value determined here is consistent with the values in ICRP Publication 67 of 5x10(-4) for ages 1 to adult, and is the same as that suggested by the NRPB.

137Cs exposure in the Marshallese populations: an assessment based on whole-body counting measurements (1989-1994)

The Marshall Islands were the site of numerous tests of nuclear weapons by the United States. From 1946 to 1958, nuclear devices were detonated at Enewetak and Bikini Atolls. Following the inadvertent contamination of the northern islands downwind of the 1954 Bravo Test, Brookhaven National Laboratory became involved in the medical care and the radiological safety of the affected populations. One important technique employed in assessing the internally deposited radionuclides is whole-body counting. To estimate current and future exposures to 137Cs, data from 1989 to 1994 were analyzed and are reported in this paper. During this period, 3,618 measurements were made for the Marshallese. The cesium body contents were assumed to result from a series of chronic intakes. Also, it was assumed that cesium activity in the body reaches a plateau that is maintained over 365 d. We estimated the annual effective dose rate for each population, derived from the recommendations of the International Commission on Radiological Protection. The average 137Cs uptake measured by the whole-body counting method varies from one population to another; it was consistent with measurements of external exposure rate. The analysis, though based on limited data, indicates that there is no statistical support for a seasonal effect on 137Cs uptake. The critical population group for cesium uptake is adult males. Within the 5-y monitoring period, all internal exposures to 137Cs were less than 0.2 mSv y(-1). Similarly, a persistent average cesium effective dose rate of 2 microSv y(-1) was determined for Majuro residents.

Assessment of plutonium exposure in the Enewetak population by urinalysis

Since 1980, the inhabitants of Enewetak Atoll have been monitored periodically by scientists from Brookhaven National Laboratory for internally deposited radioactive material. In 1989, the establishment of fission track analysis and of a protocol for shipboard collection of 24-h urine samples significantly improved our ability to assess the internal uptake of plutonium. The purpose of this report is to show the distribution of plutonium concentrations in urine collected in 1989 and 1991, and to assess the associated committed effective doses for the Enewetak population based on a long-term chronic uptake of low-level plutonium. To estimate dose, we derived the plutonium dose-per-unit-uptake coefficients based on the dosimetric system of the International Commission on Radiological Protection. Assuming a continuous uptake, an integrated Jones's plutonium urine excretion function was developed to interpret the Enewetak urine data. The Appendix shows how these values were derived. The committed effective doses were 0.2 mSv, calculated from the 1991 average plutonium content in 69 urine samples.

Assessment of plutonium exposures in Rongelap and Utirik populations by fission track analysis of urine

A nuclear device, code-named Bravo, detonated at Bikini Atoll at 6:45 a.m. on 1 March 1954, unexpectedly released a large amount of radioactivity. Over 40 years after this incident, the study of its impact on the radiological health and environmental safety of the residents of Rongelap and Utirik Atolls continues. In 1987, researchers at Brookhaven National Laboratory established a fission track analysis (FTA) method for low-level 239Pu urinalysis. Two years later, a new shipboard protocol was developed for collecting 24-h radiologically clean urine samples. The purpose of this paper is to update information on the FTA method for measuring low-levels of plutonium, and to summarize results on the distribution of 239Pu in the populations of Rongelap and Utirik between 1981-1991. Plutonium detection levels (99% confidence level) in these samples were 2-3 microBq, which is equivalent to 0.2-0.3 mSv effective dose equivalent (EDE) to age 70 for Marshallese. The latest 1991 FTA data indicate average EDE of 0.62 mSv and 1.6 mSv for the people of Rongelap and Utirik, respectively, which both are the highest values since 1988.