Preparation, design, identification and application of self-assembly peptides from seafood: A review.

Hydrogels formed by self-assembling peptides with low toxicity and high biocompatibility have been widely used in food and biomedical fields. Seafood contains rich protein resources and is also one of the important sources of natural bioactive peptides. The self-assembled peptides in seafood have good functional activity and are very beneficial to human health. In this review, the sequence of seafood self-assembly peptide was introduced, and the preparation, screening, identification and characterization. The rule of self-assembled peptides was elucidated from amino acid sequence composition, amino acid properties (hydrophilic, hydrophobic and electric), secondary structure, interaction and peptide properties (hydrophilic and hydrophobic). It was introduced that the application of hydrogels formed by self-assembled peptides, which lays a theoretical foundation for the development of seafood self-assembled peptides in functional foods and the application of biological materials.

Identification and characterization of a calcium-binding peptide from salmon bone for the targeted inhibition of α-amylase in digestion.

α-Amylase, essential for carbohydrate digestion, relies on calcium (Ca) for its structural integrity and enzymatic activity. This study explored the inhibitory effect of salmon bone peptides on α-amylase activity through their interaction with the enzyme's Ca-binding sites. Among the various salmon bone hydrolysates, salmon bone trypsin hydrolysate (SBTH) exhibited the highest α-amylase inhibition. The peptide IEELEEELEAER (PIE), with a sequence of Ile-Glu-Glu-Leu-Glu-Glu-Glu-Glu-Leu-Glu-Ala-Glu-Arg from SBTH, was found to specifically target the Ca-binding sites in α-amylase, interacting with key residues such as Asp206, Trp203, His201, etc. Additionally, cellular experiments using 3 T3-L1 preadipocytes indicated PIE's capability to suppress adipocyte differentiation, and decreases in intracellular triglycerides, total cholesterol, and lipid accumulation. In vivo studies also showed a significant reduction in weight gain in the group treated with PIE(6.61%)compared with the control group (33.65%). These findings suggest PIE is an effective α-amylase inhibitor, showing promise for obesity treatment.

Characterizations and the Mechanism Underlying Cryoprotective Activity of Peptides from Enzymatic Hydrolysates of Pseudosciaena crocea.

Antifreeze peptides are a class of small molecule protein hydrolysates that protect frozen products from cold damage under freezing or subcooling conditions. In this study, three different Pseudosciaena crocea (P. crocea) peptides were from pepsin, trypsin, and neutral protease enzymatic hydrolysis. It aimed to elect the P. crocea peptides with better activity through molecular weight, antioxidant activity, and amino acid analysis, as well as to compare the cryoprotective effects with a commercial cryoprotectant. The results showed that the untreated fillets were prone to be oxidized, and the water-holding capacity after freeze-thaw cycle decreased. However, the treatment of the trypsin hydrolysate of P. crocea protein significantly promoted the water-holding capacity level and reduced the loss of Ca2+-ATP enzyme activity and the structural integrity damage of myofibrillar protein in surimi. Moreover, compared with 4% sucrose-added fillets, trypsin hydrolysate treatment enhanced the umami of frozen fillets and reduced the unnecessary sweetness. Therefore, the trypsin hydrolysate of P. crocea protein could be used as a natural cryoprotectant for aquatic products. Hence, this study provides technical support for its use as a food additive to improve the quality of aquatic products after thawing and provides a theoretical basis and experimental foundation for the in-depth research and application of antifreeze peptides.

Nutritional properties and osteogenic activity of simulated digestion components and peptides from Larimichthys crocea.

Fish provides a range of health benefits due to its nutritional and bioactive components. However, the bioactive peptides derived from Larimichthys crocea proteins were not fully investigated, especially the beneficial effects related to bone growth in vitro. In this study, the water extract protein was subjected to the simulated in vitro digestion process, and the osteogenic effect of enzymatic hydrolysate at different digestion stages was evaluated by the proliferation of osteoblast. The protein hydrolyzates of group pepsin treatment for 1 h and pepsin treatment for 2 h showed higher osteogenic activity in vitro. Two peptides including IERGDVVVQDSPSD from pepsin treatment for 1 h and RGDLGIEIPTEK from pepsin treatment for 2 h were identified, which revealed eminent effects in terms of promoting osteoblast proliferation and enhancing ALP activity. Moreover, the available nutrients in the proteins were determined by the molecular weight distribution and free amino acid composition. Those peptides also showed stronger interaction with RGD than integrins. Therefore, the peptides from Larimichthys crocea can be used as an effective ingredient for promoting bone growth in the future.

Characterization of Chelation and Absorption of Calcium by a Mytilus edulis Derived Osteogenic Peptide.

In a previous study, the peptide LGKDQVRT, which was identified by enzymatic hydrolysis, released during the proteolysis of Mytilus edulis, had potential osteogenic activity. In this study, the octapeptide LGKDQVRT was able to spontaneously bind calcium in a 1:1 stoichiometric ratio, and the calcium-binding site likely involves calcium and amino acid VAL6 in the LGKDQVRT peptide to form a metal-donor to metal acceptor complex. The peptide LGKDQVRT has the activity of promoting the proliferation and differentiation of osteoblasts. The results of this study suggest that hydrolyzed peptides from Mytilus edulis protein can be used as a dietary supplement to improve calcium absorption and prevent osteoporosis.

A Type IIb, but Not Type IIa, GnRH Receptor Mediates GnRH-Induced Release of Growth Hormone in the Ricefield Eel.

Multiple gonadotropin-releasing hormone receptors (GnRHRs) are present in vertebrates, but their differential physiological relevances remain to be clarified. In the present study, we identified three GnRH ligands GnRH1 (pjGnRH), GnRH2 (cGnRH-II), and GnRH3 (sGnRH) from the brain, and two GnRH receptors GnRHR1 (GnRHR IIa) and GnRHR2 (GnRHR IIb) from the pituitary of the ricefield eel Monopterus albus. GnRH1 and GnRH3 but not GnRH2 immunoreactive neurons were detected in the pre-optic area, hypothalamus, and pituitary, suggesting that GnRH1 and GnRH3 may exert hypophysiotropic roles in ricefield eels. gnrhr1 mRNA was mainly detected in the pituitary, whereas gnrhr2 mRNA broadly in tissues of both females and males. In the pituitary, GnRHR1 and GnRHR2 immunoreactive cells were differentially distributed, with GnRHR1 immunoreactive cells mainly in peripheral areas of the adenohypophysis whereas GnRHR2 immunoreactive cells in the multicellular layers of adenohypophysis adjacent to the neurohypophysis. Dual-label fluorescent immunostaining showed that GnRHR2 but not GnRHR1 was localized to somatotropes, and all somatotropes are GnRHR2-positive cells and vice versa at all stages examined. GnRH1 and GnRH3 were shown to stimulate growth hormone (Gh) release from primary culture of pituitary cells, and to decrease Gh contents in the pituitary of ricefield eels 12 h post injection. GnRH1 and GnRH3 stimulated Gh release probably via PLC/IP3/PKC and Ca2+ pathways. These results, as a whole, suggested that GnRHs may bind to GnRHR2 but not GnRHR1 to trigger Gh release in ricefield eels, and provided novel information on differential roles of multiple GnRH receptors in vertebrates.

Performance improvement of NOMA visible light communication system by adjusting superposition constellation: a convex optimization approach.

Non-orthogonal multiple access (NOMA) can increase the overall spectral efficiency of visible light communication (VLC) system. In this paper, we proposed a novel scheme to improve the bit error rate (BER) performance of a two-user NOMA VLC system by adjusting superposition constellation. The corresponding closed-form BER expressions are derived. Convex optimization is used to find the optimal parameters of the adjusted superposition constellation, where the overall BER is minimized. The BER performances are evaluated by theoretical analysis, Monte-Carlo (MC) simulation and experiment. The results illustrate that 8.9-dB and 8.1-dB signal-to-noise ratios (SNRs) are reduced to achieve BER of 10-3 for the two users, whose power allocation coefficients are 0.6 and 0.4, respectively.

[Effectiveness evaluation of prosthetic revision for aseptic loosening in oncology prosthesis].

OBJECTIVE: To evaluate the effectiveness of prosthetic revision using custom-made long stem prosthesis and allograft-prosthesis composite (APC) for aseptic loosening after bone tumor resection. METHODS: Between January 2002 and June 2008, 14 patients with aseptic loosening after bone tumor resection were treated. There were 8 males and 6 females, aged 21-70 years (mean, 43.9 years). The locations were distal femur (8 cases), proximal femur (2 cases), and proximal tibia (4 cases). Pain of the affected limb occurred after 6-31 years of prosthesis replacement and worsened when bearing and walking; 6 patients had shortened limb. The functional results were assessed quantitatively according to the functional rating system of the Musculoskeletal Tumor Society (MSTS). The MSTS score was 16.36 +/- 1.50 before revision. The X-ray films showed obvious prosthetic loosening and subsidence. The average time of symptom was 4.5 years (range, 3-9 years). In 7 patients having severe bone loss (the decrease of the thickness of cortical bone was more than 50%) and the prosthetic subsidence was more than 2 cm, the revision operation with the APC was performed; in 7 patients having less bone loss (the decrease of the thickness of cortical bone was less than 50%), the custom-made long stem prosthesis was performed. RESULTS: All wound healed by first intention. Two patients had temporary peroneal nerve paralysis and recovered after 3 months. All the patients were followed up 3.6 years on average (range, 2 years and 2 months- 7 years) after revision. After revision, pain was relieved and the range of joint was improved. The MSTS score was 23.43 +/- 2.56 at 12 months after revision showing significant difference when compared with the preoperative score (t = 8.910, P = 0.024). The X-ray films showed that lucency space line around stem cement in 2 patients at 12 months, and no prosthesis loosening and infection occurred. CONCLUSION: The prosthetic revision after limb salvage surgery with prosthesis for bone tumors was acceptable. The good functional results can be achieved by the revision with the APC or the custom-made long stem prosthesis according to the bone loss.

[Surgical treatment of proximal femoral malignant tumors].

OBJECTIVE: To evaluate the clinical outcomes of the wide resection and the functional reconstruction for treating malignant tumors of the proximal femur. METHODS: The clinical data were analysed from 62 patients with malignant tumors of the proximal femur treated between January 1987 and December 2007. There were 29 males and 33 females with a median age of 35 years (range, 14-73 years). In 41 patients with primary malignant tumors having a disease course of 0.5-14.0 months, there were 16 cases of osteosarcoma, 7 cases of fibrosarcoma, 6 cases of chondrosarcoma, 6 cases of malignant fibrous histiocytoma, 4 cases of mesenchymal sarcoma,1 case of Ewing sarcoma, and 1 case of angiosarcoma, including 3 cases of type IB, 2 cases of type IIA, 35 cases of type IIB, and 1 case of type III according to Enneking stage. In 21 patients with metastatic tumors, 16 had a malignant tumor history; the disease course was 0.1-28.0 months (3.4 months on average). Radical resection was performed in 9 cases, extensive resection in 39 cases, and marginal resection in 14 cases. After resection, 39 cases underwent reconstruction with prostheses (prostheses group) and 14 cases underwent reconstruction with allograft-prosthetic composites (APC, APC group). RESULTS: All incision healed by first intention. Twenty-six cases died of tumor metastasis, their postoperative survive time was 16-56 months (28 months on average). The average follow-up time was 64 months (range, 28-221 months) in 36 survival patients. The local recurrence rate of primary malignant tumors was 4.88% (2/41). In prostheses group, dislocation of femoral head occurred in 2 cases, fracture of prosthetic stem in 1 case, hip pain in 3 cases, acetabular wear in 3 cases, and stem loosening in 5 cases. In APC group, nonunion of APC occurred in 3 cases and acetabular wear in 1 case. At last follow-up, the average Musculoskeletal Tumor Society (MSTS) functional scores were 77.69% +/- 6.50% in prostheses group and 85.71% +/- 7.45% in APC group, showing significant difference (P < 0.001). CONCLUSION: When the wide resection is performed for malignant tumors of the proximal femur, better local control could be achieved. Compared with reconstruction of the prosthesis, the APC reconstruction can provide better function.

Primary non-Hodgkin's lymphoma of the spine with neurologic compression treated by radiotherapy and chemotherapy alone or combined with surgical decompression.

Neurologic compression is a disastrous consequence for the patients with primary non-Hodgkin's lymphoma (NHL) of the spine, and such a condition has not been carefully taken into account in the treatment guidelines. The aim of this study was to compare the effect of radiotherapy and chemotherapy alone or combined with surgical decompression on primary NHL of the spine with neurologic compression. Sixteen patients with primary NHL in the vertebrae of the spine were treated between 1994 and 2006. Thirteen patients had neurologic compression. The neurologic deficits in 11 patients involved soft tissue extension from the vertebral tumors and 3 had vertebral fractures with motor signs and 5 had radicular pain. Five patients were treated by radiotherapy and chemotherapy alone while 8 were combined with surgical decompression. The decompression operation for tumors resulted in neurologic recovery in 6 patients. Five patients were not operated on but three received emergent radiotherapy before chemotherapy, 4 of whom had complete recovery in their neurologic symptoms. Of all patients, 3 relapsed. At average follow-up of 61.5 months (range 2-156 months), 4 patients had died after an average interval of 23.3 months from treatment (range 3-71 months). The 5-year overall survival rate was 82% with 60% for the patients in the surgical group, 100% for the patients in the non-surgical group. There was no difference between the groups (chi(2)=3.559, P=0.059). The 5-year overall survival was 100% for the 8 patients who completed CHOP chemotherapy and radiotherapy. It appears that optimum treatment in these patients depends on the cause of the neurologic deficits, whereas the survival is not influenced by the surgical or non-surgical treatment. The results suggest that chemotherapy and radiotherapy alone is the ideal treatment for these patients whose neurologic compression was only due to soft tissue extension. The authors emphasize the importance of chemotherapy and radiotherapy followed by surgical decompression depending on individual priorities in the indications for operation on primary NHL of spine with neurologic compression.