Endoscopic reconstruction for chronic Achilles tendon ruptures using a hamstring tendon autograft.

BACKGROUND: To determine the safety and efficacy of endoscopic reconstruction of chronic Achilles tendon ruptures using a hamstring tendon autograft at mid-term follow-up. METHODS: We reviewed the medical records of patients with chronic Achilles tendon rupture treated surgically by endoscopic reconstruction using a hamstring tendon autograft at our institution between March 2010 and October 2015. Radiologic outcomes were assessed using pre- and postoperative magnetic resonance imaging (MRI). Functional outcomes were evaluated with the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Scale, the Plantar Flexion Strength (PFS), the Victorian Institute of Sport Assessment-Achilles (VISA-A) scale, the Visual Analogue Scale (VAS) pain score, and the Arner-Lindholm standard. All patients achieved primary healing with no lengthening of the Achilles tendon, skin necrosis, infection, deep vein thrombosis or other complications. RESULTS: Mean follow-up period was 15 ± 3 months (range, 12-18 months). There was no Achilles tendon re-rupture. MRI examination revealed that Achilles tendon continuity was restored. Patients' mean AOFAS, PFS, and VISA-A scores were significantly higher and mean VAS pain score was significantly lower after surgery compared to before (P < 0.05). According to Arner-Lindholm standards, there were twenty (76.9%) excellent, six (23.1%) good, and zero bad outcomes. CONCLUSION: Endoscopic reconstruction utilizing a hamstring tendon autograft is a safe and efficacious option for repair of chronic Achilles tendon ruptures. Studies with larger sample sizes and a longer follow-up are required to confirm the advantage of this technique compared to open surgery.

LGN/mInsc and LGN/NuMA complex structures suggest distinct functions in asymmetric cell division for the Par3/mInsc/LGN and Gαi/LGN/NuMA pathways.

Asymmetric cell division requires the establishment of cortical cell polarity and the orientation of the mitotic spindle along the axis of cell polarity. Evidence from invertebrates demonstrates that the Par3/Par6/aPKC and NuMA/LGN/Gαi complexes, which are thought to be physically linked by the adaptor protein mInscuteable (mInsc), play indispensable roles in this process. However, the molecular basis for the binding of LGN to NuMA and mInsc is poorly understood. The high-resolution structures of the LGN/NuMA and LGN/mInsc complexes presented here provide mechanistic insights into the distinct and highly specific interactions of the LGN TPRs with mInsc and NuMA. Structural comparisons, together with biochemical and cell biology studies, demonstrate that the interactions of NuMA and mInsc with LGN are mutually exclusive, with mInsc binding preferentially. Our results suggest that the Par3/mInsc/LGN and NuMA/LGN/Gαi complexes play sequential and partially overlapping roles in asymmetric cell division.

Effect of autologous platelet-rich plasma in combination with bovine porous bone mineral and bio-guide membrane on bone regeneration in mandible bicortical bony defects.

OBJECTIVE: Growth factors contained in platelet-rich plasma (PRP) can induce osteoblast differentiation in certain studies, whereas in others, osteogenesis of PRP on mandible bone defects has not been proved clinically. The aim of the study was to investigate the effect of autologous PRP on the osteogenic potential of combining bovine porous bone mineral (BPBM) and bio-guide membrane (BGM) in promoting mandible bicortical bony defects in rabbits. METHODS: One circular mandible bicortical bony defects were created in each of 54 rabbits, which were divided into 3 groups: group 1: 18 of the defects were left unfilled as a negative control; group 2: 18 of the defects were grafted with autologous PRP and BPBM/BGM; group 3: 18 of the defects were grafted with BPBM/BGM without PRP. Animals were killed at 4, 8, and 12 weeks after operation. Harvested tissue and specimens were evaluated histologically and radiographically, and metabolized observation was performed. Histological parameters associated with osteoblast activities, bone trabecula, neovascularization, newly formed mineralized bone, rudimental grafts and connective tissue formation were measured. Densities of the bones at 4, 8, and 12 weeks were studied by radiographic. The bone defect closure ratio was measured at 12 weeks. The bone metabolized parameter alkaline phosphatase was also measured and compared between 4, 8, and 12 weeks. RESULTS: The platelet concentration of PRP is 4.19- to 4.43-fold to that of the whole blood. Histological analysis showed new bone formation at all therapeutic sites including BPBM/BGM grafts with or without PRP. A statistically significant difference in new bone formation between group PRP/BPBM/BGM and group BPBM/BGM was observed. Untreated defects of group control showed the less bone regeneration. There was significant difference of bone density between group PRP/BPBM/BGM and control, and group BPBM/BGM and control, at 4, 8, and 12 weeks postoperative. There were more bone defects filling, and the grafts were absorbed at 12 weeks of group PRP/BPBM/BGM compared with group BPBM/BGM. Defects treated with PRP/BPBM/BGM demonstrated significantly increased activity of osteoblasts, enhanced amount of mitochondria and rough endoplasmic reticulum in osteoblasts, and increased concentration of alkaline phosphatase at 4, 8, and 12 weeks compared with those treated with BPBM/BGM and control group. Complete closure ratio of bone defects treated with PRP/BPBM/BGM (50%) was significantly increased compared with that treated with BPBM/BGM (16.6%). CONCLUSIONS: The study suggested that PRP combination of BPBM and BGM had significant therapeutic effects on mandible bicortical bony defects of rabbits. The effects are associated with the high concentration of platelet in PRP and the porous configuration of BPBM. Although we cannot reveal the detailed statistical relationship of PRP on promoting BPBM/GBM osteoinductive effects, PRP demonstrated superior results of bone regeneration.

Solution structure of the SH3 domain of DOCK180.

DOCK180 family proteins are Rho guanine nucleotide exchange factors. DOCK1-5 contains an N-terminal SH3 domain implicated in their autoinhibition. Release of the closed conformation requires the interaction between SH3 and engulfment and cell motility (ELMO). Here, we solved the solution structure of DOCK180 SH3 domain, which shares similar target binding features with the SH3 domain of DOCK2. The conserved N-terminal extension packs with the SH3 core domain and forms a new target binding site distinct from the canonical "PxxP" site. Our results demonstrate that the bidentate target binding mode of DOCK180 SH3 domain might be a general feature in all DOCK proteins.

Nanomaterials as Promising Additives for High-Performance 3D-Printed Concrete: A Critical Review.

Three-dimensional (3D) printed concrete (3DPC), as one of the subset of digital fabrication, has provided a revolution in the construction industry. Accordingly, scientists, experts, and researchers in both academic and industry communities are trying to improve the performance of 3DPC. The mix design of all kinds of concrete has always been the most crucial property to reach the best efficiency. Recently, many studies have been performed to incorporate nano- and micro-scale additives to ameliorate the properties of 3DPC. The current study aims to present the main design properties of 3DPC and completely cover both fresh and hardened state characteristics of 3DPC containing different nano- and micro-additives. Our observations illustrate that nanomaterials can be mainly utilized as a thickener to ameliorate the thixotropic behavior and the structural build-up of 3DPC, resulting in higher yield stress and better viscosity recovery. Furthermore, each nanomaterial, through its unique impact, can provide lower porosity and permeability as well as better mechanical strengths for 3DPC. Although much research investigate the fresh properties of 3DPC containing nano and micro additives, future studies are needed to provide better insight into the impact of these kinds of additives on the hardened characteristics of 3DPC. In addition, researchers may devote more research to address the effects of the additives discussed herein on the performance of other kinds of 3DPC such as lightweight, self-compacting, etc. It should be noted that the effect mechanism of nanomaterials on the inter-layer bond strength of 3DPC is another crucial issue that should be investigated in future studies. Furthermore, nano-scale fillers from source of waste and biomass can be attractive additives for future research to achieve high performance of sustainable 3D-printed concrete.

Analysis of type I hypersensitivity-induced inflammatory response in children of different age groups with acute appendicitis.

OBJECTIVE: To explore the differences in type I hypersensitivity-induced inflammatory response among children of different age groups with acute appendicitis. METHODS: We selected children diagnosed with "acute appendicitis" who underwent surgery in the Department of General Surgery of Anhui Provincial Children's Hospital from January 2022 to June 2022 and collected their basic data. We divided them into two groups according to age: the infant group (less than 3 years old) and the pediatric group (3-14 years old). The gender, age, onset time, hospital stay, preoperative white blood cells, percentage of neutrophils, C-reactive protein (CRP), and enzyme-linked immunosorbent assay (ELISA) were collected to determine the levels of immunoglobulin E (IgE), interleukin-4 (IL-4), interleukin-5 (IL-5), interleukin-6 (IL-6), and interleukin-9 (IL-9) in appendicular lavage fluid, and the differences between the two groups were compared. RESULTS: There were 15 children in the infant group and 15 in the pediatric group. There was no significant difference between the two groups with respect to onset time and gender. The hospitalization time in the pediatric group was (5.7 ± 2.1) d, the preoperative white blood cells were (14.3 ± 3.7) × 10^9/mL, neutrophil percentage was (84.5 ± 6.3)%, and CRP was (20.0 ± 17.9) mg/mL. The hospitalization time of the infant group was (8.0 ± 3.1) d, the preoperative white blood cells were (19.0 ± 3.8) × 10^9/mL, neutrophil percentage was (77.8 ± 10.4)%, and CRP was (42.5 ± 25.0) mg/mL. The differences between the two groups were significant. There was no significant difference in IL-5 concentration between the two groups in the appendicular lavage fluid. IgE (610.74 ± 72.56) ng/mL, IL-4 (30.80 ± 12.04) ng/mL, IL-6 (118.09 ± 14.29) ng/mL, IL-9 (133.94 ± 16.00) ng/mL were found in the infant group, and IgE (495.61 ± 95.09) ng/mL, IL-4 (22.68 ± 7.05) ng/mL, IL-6 (98.22 ± 22.18) ng/mL and IL-9 (107.86 ± 27.34) ng/mL were found in the pediatric group, and the differences between the two groups were statistically significant. CONCLUSIONS: The inflammatory response in children with acute appendicitis was associated with type I hypersensitivity-induced inflammatory responses, and the type I hypersensitivity was more intense in children in the lower age group.

A Case of Ulcerative Colitis Induced by Paraneoplastic Syndrome?

Background: Paraneoplastic syndromes often cause endocrine, neurological, cutaneous, and hematologic pathologies, and cases with digestive symptoms as prominent cases are rare. Case Description: A 1-year-old child admitted to the emergency department with severe abdominal distension was later diagnosed with sacrococcygeal yolk cystoma with ulcerative colitis. After symptomatic management, surgical removal of the tumor, and JEB chemotherapy, the symptoms of ulcerative colitis disappeared completely. After 7 years of follow-up, the child grew and developed well, and there was no recurrence of tumor and ulcerative colitis. Conclusion: Yolk sac tumor with ulcerative colitis is a rare paraneoplastic syndrome with complex clinical manifestations.

Use of Municipal Solid Waste Incineration Fly Ash in Geopolymer Masonry Mortar Manufacturing.

The feasibility of partially replacing pulverized fly ash (PFA) with municipal solid waste incineration fly ash (MSWIFA) to produce ambient-cured geopolymers was investigated. The influence of mixture design parameters on the compressive strength of geopolymer paste was studied. The investigated parameters included MSWIFA dosage, the ratio of sodium silicate to sodium hydroxide (SS/SH), the ratio of liquid to solid (L/S) alkaline activator, and the ratio of SH molar. A water immersion method was selected as a pretreatment process for MSWIFA, leading to effectively maintaining the volume stability of the MSWIFA/PFA geopolymer. The mixture of 30% treated MSWIFA and 70% PFA with 12 M SS, 0.5 L/S ratio, and 3.0 SS/SH ratio produced the highest three-day compressive strength (4.9 MPa). Based on the optimal paste mixture, category four masonry mortars (according to JGJT98-2011) were prepared to replace various ratios of natural sand with fine recycling glasses. Up to a 30% replacement ratio, the properties of the mortars complied with the limits established by JGJT98-2011. The twenty-eight-day leaching rate of mortars containing 30% MSWIFA was lower than the limits proposed by GB5085.3-2007. Microstructural analysis indicated that the main reaction product was a combination of calcium silicate hydrate gel and aluminosilicate gel.

[Differences in uptake, utilization and loss of nitrogen and phosphorus in a Chinese double rice cropping system under different irrigation and fertilization managements]. / 不同水肥耦合下双季稻氮磷吸收、利用与流失差异.

In order to optimize water and fertilizer use in the double-cropping rice in eastern Fujian Province, a field runoff plot experiment was conducted to investigate rice yield, nutrient uptake, and runoff losses of N (nitrogen) and P (phosphorus) in the T0(no chemical fertilization with traditional flooding irrigation), T1(common chemical fertilizer of 273 kg N·hm-2, 59 kg P·hm-2, and 112 kg K·hm-2 combined with traditional flooding irrigation), T2(chemical fertilizer of 240 kg N·hm-2, 52 kg P·hm-2, and 198 kg K·hm-2 combined with traditional flooding irrigation) and T3(chemical fertilizer combined with shallow intermittent irrigation) treatments. Results showed that early rice grain yield in the T1, T2 and T3 treatments significantly increased by 0.7, 1.0, 1.1 times, late rice grain yield significantly increased by 0.9, 1.1, 1.0 times compared to that in the T0 treatment, respectively. The T1, T2 and T3 treatments significantly increased the uptake of N and P in aboveground parts of the plants, especially in grains. The T1, T2 and T3 treatments significantly increased N uptake by 1.1, 1.2, 1.2 times, increased P uptake by 0.9, 1.4, 1.6 times in early-season grains, and significantly increased N uptake by 0.8, 1.0, 1.0 times, increased P uptake by 0.7, 0.9, 0.9 times in late-season grains, compared to T0, respectively. Furthermore, T3 increased agronomic N use efficiency (AEN) and agronomic P use efficiency (AEP) by 71.1% and 69.2% in early rice plants, increased AEN and AEP by 26.4% and 25.0% in late rice plants, whereas T3 decreased total dissolved N (DN) by 16.0% in comparison with T1. Dissolved inorganic N loss in surface runoff occurred mainly in the form of NO3--N (nitrate N) under different water and fertilizer regimes. However, there were no significant differences in AEN and AEP between T2 and T3 treatments. These findings suggested that optimal applications of water and fertilizers (T3) might increase N and P uptake in rice plants, maintain yield, and reduce N loss, especially in the form of NO3--N in surface water from early rice field. In general, this study could provide theoretical support for the optimization of irrigation and fertilization and for the control of N and P non-point source pollution from the double cropping rice paddy fields in eastern Fujian Province.

Epigenetics and genetics of hepatoblastoma: Linkage and treatment.

Hepatoblastoma is a malignant embryonal tumor with multiple differentiation modes and is the clearest liver malignancy in children. However, little is known about genetic and epigenetic events in Hepatoblastoma. Increased research has recently demonstrated, unique genetic and epigenetic events in Hepatoblastoma, providing insights into its origin and precise treatment. Some genetic disorders and congenital factors are associated with the risk of Hepatoblastoma development, such as the Beckwith-Wiedemann syndrome, Familial Adenomatous polyposis, and Hemihypertrophy. Epigenetic modifications such as DNA modifications, histone modifications, and non-coding RNA regulation are also essential in the development of Hepatoblastoma. Herein, we reviewed genetic and epigenetic events in Hepatoblastoma, focusing on the relationship between these events and cancer susceptibility, tumor growth, and prognosis. By deciphering the genetic and epigenetic associations in Hepatoblastoma, tumor pathogenesis can be clarified, and guide the development of new anti-cancer drugs and prevention strategies.

Application of Noncontact Laparoscopic High Ligation of the Hernia Sac of the Vas Deferens in Children with Indirect Inguinal Hernia.

Objective: This study aims to evaluate the usefulness of vas deferens noncontact laparoscopic high ligation of the hernia sac in children with indirect inguinal hernia (IIH). Materials and Methods: The clinical data of 146 male children with IIH treated in the Anhui Children's Hospital from January 2018 to June 2019 were analyzed retrospectively. There were 82 patients in the observation group in which the inner ring opening was sutured and closed using the vas deferens noncontact suture and 64 patients in the control group in which the peritoneum at the inner ring opening was closed using the intradermal suture. The operation time, surgical complications, postoperative complications, and recurrence rate were compared between the two groups (followed up for 2 years). Results: The operation was successful in all the patients in both groups. In the observation group, there was one case of intraoperative spermatic cord vascular injury and one case of infra-abdominal wall vascular injury, and no intraoperative complications occurred in the control group. The operation time was 12.8 ± 1.4 minutes in the control group and 10.4 ± 2.6 minutes in the observation group (P < .01). The two groups of patients were followed up for 2 years, and no complications and no recurrence occurred. Conclusion: The vas deferens noncontact laparoscopic high ligation of the hernia sac to close the inner ring opening has several advantages: The operation is simple; the operation time is shorter than the traditional method, avoiding the possibility of vas deferens injury; and it is a safe, reliable, and effective surgical method. However, due to the small number of clinical cases in this study, its long-term effect requires further observation.

[Analysis of fund sponsored articles from five ophthalmologic journals in 2005].

OBJECTIVE: To reveal the features of fund sponsored articles and the status of scientific research by analyzing fund sponsored articles from 5 ophthalmologic journals in Chinese. METHODS: Five ophthalmologic journals (Chinese Journal of Ophthalmology, Chinese Journal of Ocular Trauma and Occupational Eye Disease with Ophthalmic Surgery, Chinese Ophthalmic Research, Chinese Journal of Practical Ophthalmology, Chinese Journal Ocular Fundus Disease) published in Chinese in 2005 were selected for this study. The amount, the distribution of region, the number of co-authors, the research direction, the number of funds obtained by each paper and the distribution of subjects in various research fields of fund sponsored articles were calculated by quantitative analysis methods. RESULTS: Among 1745 articles published in 2005, 222 were supported by various funds (12.72%). Articles sponsored by national, province/ministry and other sources accounted for 4.70%, 4.81% and 3.21% of all articles, respectively. The highest numbers of co-authors was 5.21. The top region of authors was located in Guangdong Province, which published 71 over 222 papers (31.98%). One hundred and forty nine papers (67.12%) were sponsored by single fund. The subject of fund sponsored articles were mainly in the field of retina (22.97%, 51/222), cornea (17.12%, 38/222) and lens (11.26%, 25/222). CONCLUSIONS: The quantity and the level of fund sponsored articles had been improved greatly in ophthalmology journals. However, this is still inferior to other bio-scientific journals. The whole academic level of ophthalmology journals should be further promoted.

In Situ Elevated Temperature Testing of Fly Ash Based Geopolymer Composites.

In situ elevated temperature investigations using fly ash based geopolymers filled with alumina aggregate were undertaken. Compressive strength and short term creep tests were carried out to determine the onset temperature of viscous flow. Fire testing using the standard cellulose curve was performed. Applying a load to the specimen as the temperature increased reduced the temperature at which viscous flow occurred (compared to test methods with no applied stress). Compressive strength increased at the elevated temperature and is attributed to viscous flow and sintering forming a more compact microstructure. The addition of alumina aggregate and reduction of water content reduced the thermal conductivity. This led to the earlier onset and shorter dehydration plateau duration times. However, crack formation was reduced and is attributed to smaller thermal gradients across the fire test specimen.

Decreased Activation of Subcortical Brain Areas in the Motor Fatigue State: An fMRI Study.

One aspect of motor fatigue is the exercise-induced reduction of neural activity to voluntarily drive the muscle or muscle group. Functional magnetic resonance imaging provides access to investigate the neural activation on the whole brain level and studies observed changes of activation intensity after exercise-induced motor fatigue in the sensorimotor cortex. However, in human, little evidence exists to demonstrate the role of subcortical brain regions in motor fatigue, which is contradict to abundant researches in rodent indicating that during simple movement, the activity of the basal ganglia is modulated by the state of motor fatigue. Thus, in present study, we explored the effect of motor fatigue on subcortical areas in human. A series of fMRI data were collected from 11 healthy subjects while they were executing simple motor tasks in two conditions: before and under the motor fatigue state. The results showed that in both conditions, movements evoked activation volumes in the sensorimotor areas, SMA, cerebellum, thalamus, and basal ganglia. Of primary importance are the results that the intensity and size of activation volumes in the subcortical areas (i.e., thalamus and basal ganglia areas) are significantly decreased during the motor fatigue state, implying that motor fatigue disturbs the motor control processing in a way that both sensorimotor areas and subcortical brain areas are less active. Further study is needed to clarify how subcortical areas contribute to the overall decreased activity of CNS during motor fatigue state.

Structural and biochemical characterization of the interaction between LGN and Frmpd1.

The tetratricopeptide repeat (TPR) motif-containing protein LGN binds multiple targets and regulates their subcellular localizations and functions during both asymmetric and symmetric cell divisions. Here, we characterized the interaction between LGN-TPR motifs and FERM and PDZ domain containing 1 (Frmpd1) and reported the crystal structure of the complex at 2.4Å resolution. A highly conserved fragment at the center of Frmpd1 of ~20 residues was found to be necessary and sufficient to bind to LGN-TPR. This Frmpd1 fragment forms an extended structure and runs along the concave channel of the TPR superhelix in an antiparallel manner in the complex. Structural comparisons and biochemical studies of LGN/Frmpd1 and other known LGN/target interactions demonstrate that the LGN-TPR motifs are versatile and capable of recognizing multiple targets via diverse binding modes. Nevertheless, a conserved "E/QxEx4-5E/D/Qx1-2K/R" motif in LGN/Pins (partner of inscuteable) TPR binding proteins has been identified.

An autoinhibited conformation of LGN reveals a distinct interaction mode between GoLoco motifs and TPR motifs.

LGN plays essential roles in asymmetric cell divisions via its N-terminal TPR-motif-mediated binding to mInsc and NuMA. This scaffolding activity requires the release of the autoinhibited conformation of LGN by binding of Gα(i) to its C-terminal GoLoco (GL) motifs. The interaction between the GL and TPR motifs of LGN represents a distinct GL/target binding mode with an unknown mechanism. Here, we show that two consecutive GL motifs of LGN form a minimal TPR-motif-binding unit. GL12 and GL34 bind to TPR0-3 and TPR4-7, respectively. The crystal structure of a truncated LGN reveals that GL34 forms a pair of parallel α helices and binds to the concave surface of TPR4-7, thereby preventing LGN from binding to other targets. Importantly, the GLs bind to TPR motifs with a mode distinct from that observed in the GL/Gα(i)·GDP complexes. Our results also indicate that multiple and orphan GL motif proteins likely respond to G proteins with distinct mechanisms.

Serum thymidine kinase 1 concentration as a prognostic factor of chemotherapy-treated non-Hodgkin's lymphoma patients.

PURPOSE: This study was performed to examine possible use of thymidine kinase 1 concentration in serum (STK1) for prognosis of non-Hodgkin's lymphoma patients following chemotherapy treatment. METHODS: The STK1 levels of 37 patients were determined by enhanced chemiluminescent dot-blot assay on the day before chemotherapy, and on day 1 and day 28 after start of the treatment. The specificity and sensitivity was evaluated by Western blot with anti-TK1 IgY antibody and by receiver operating characteristic (ROC) analysis. RESULTS: Western blot and ROC analysis of TK1 in serum showed high specificity and sensitivity. The mean STK1 level of the non-Hodgkin's lymphoma patients was significantly higher compared to healthy persons (p < 0.001). The mean STK1 level increased significantly (p < 0.001) on day 1 and then declined, reaching on day 28 values corresponding to those of healthy persons. The mean STK1 values before treatment and at 1 and 28 days after start of the treatment also correlated significantly with the clinical response (CR, PR and NR) and five-year survival. CONCLUSION: Although the number of patients was limited in this study, TK1 in serum might possess an important reference value in the evaluation of treatment and prognosis of non-Hodgkin's lymphoma following chemotherapy.

[Establishment of Quantitative Assay for Human Erythrocyte Pyrimidine 5'-Nucleotidase Content by Double Antibody Sandwich ELISA]

For exploring pathogenesis of pyrimidine 5'-nucleotidase (P5'N) deficiency, a quantitative assay method for human erythrocyte pyrimidine 5'-nucleotidase was established. The specific substrate uridine monophosphate (UMP) of P5'N was used as ligand. The UPM-ADH-Sepharose 4B affinity column was prepared. P5'N of human erythrocyte was purified by ammonium sulfate fractionation and precipitation, ion chromatography and affinity chromatography. Rabbit anti-human P5'N antibody was acquired by immunizing rabbits with purified P5'N. Using rabbit anti-human antibody as the coated anti-body and HRP-rabbit anti-human antibody as demonstrated anti-body, the double antitody sandwich ELISA for quantitative assay of human erythrocyte P5'N was established after square rank trial, antigen blocked trial and antigen substituted test. Results showed that the titer of rabbit anti-human erythrocyte was 1:4 and the sensitivity of double antibody sandwich ELISA was 5 ng/ml. Its blocking rate was more than 95% and the rate of substitution less than 30%. The content of P5'N was (71.77 + 10.98) ng/mg NHP in normal human erythrocyte. A new ELISA method for quantitative determination of human erythrocyte P5'N was first established. It not only had high specificity and sensitivity but also could assay the minimun content of P5'N as 5 - 20 ng/ml. It could be a suitable method for large sample in clinics.

[Microsequencing, analysis of molecular weight and amino acid composition for pyrimidine 5'-nucleotidase I of human erythrocytes].

To further explore the mechanism of congenital pyrimidine 5'-nuleotidase I (P5'N-I) deficiency, on the basis of purification of the protein, the molecular weight and amino acid composition were analysed by mass-spectrograph and amino-acid analyzer, microsequencing and bioinformation analysis of P5'N-I were performed after it was hydrolysed by trypsin. The results showed that three fractions were found in the purified P5'N-I and their molecular weights were 26,952.9, 55,476 and 110,938, respectively. The sequence from one of the peptide fragments was I-E-G-P-T-I-R-Q-I-E. The homologous sequence was not found after comparision with the ten-amino-acid sequence in GenBank by blast procedure. Amino acid analysis indicated that P5'N-I was composed of 18 amino acids at least, and 243 amino acid residues. In conclusion, the enzyme might be an allosteric enzyme, there might be homologous dimer or tetramer in physiological status of normal human erythrocyte, the microsequence could be designed as the probe for fishing the genes of interest. The composition of amino acid might be an important information in determination of its protein primary structure.