Advance in screening and diagnosis of obstructive sleep apnea-hypopnea syndrome in children / 国际儿科学杂志

Obstuctive sleep apnea-hypopnea syndrome(OSAHS) is a kind of disease that seriously endangers children′s health, which can disrupt children′s normal ventilation and sleep structure.Untreated OSAHS in children can cause damage to multiple systems, including cardiovascular, metabolic, endocrine and neurocognitive systems and even to death.Although polysomnography is the gold standard for the diagnosis of OSAHS in children, it is thought to be costly, labor-intensive, uncomfortable and the limitation of medical conditions in some areas, many patients can not obtain timely diagnosis.Therefore, it is necessary to find a simple and effective method for early screening of OSAHS in children.

Safety, Immunogenicity, and Efficacy of COVID-19 Vaccine in Children and Adolescents: A Systematic Review

AimTo identify the safety, immunogenicity, and protective efficacy of COVID-19 vaccine in children and adolescents. MethodsWe conducted a systematic review. Databases including PubMed, Web of Science, WHO COVID-19 database, and CNKI were searched on 23 July 2021. International Clinical Trials Registry Platform (ICTRP) was also searched to collect ongoing trials. We included published researches or ongoing clinical trials related to the safety, immunogenicity, and efficacy of COVID-19 vaccine in children or adolescents (aged [≤]18 years). Meta-analysis was performed if the consistency of the included studies was high. If not, descriptive analyses were performed. ResultsEight published studies with 2851 children or adolescents and 28 ongoing clinical trials were included. Among eight published studies, two (25.0%) were RCTs, two (25.0%) case series, and four (50.0%) case reports. The results showed selected COVID-19 vaccines had a good safety profile in children and adolescents. Injection site pain, fatigue, headache, and chest pain were the most common adverse events. Some studies reported a few cases of myocarditis and pericarditis. Two RCTs showed that the immune response to BNT162b2 in adolescents aged 12-15 years was non-inferior to that in young people aged 16-25 years, while a stronger immune response was detected with 3g CoronaVac injection. Only one single RCT showed the efficacy of BNT162b2 was 100% (95% CI: 75.3 to 100). Of the 28 ongoing clinical trials, twenty-three are interventional studies. Fifteen countries are conducting interventional clinical trials of COVID-19 vaccines in children and adolescents. Among them, China (10, 43.5%) and United Stated (9, 39.1%) were the top two countries with the most trials. BNT162b2 was the most common vaccine, which is under testing. ConclusionSome of the COVID-19 vaccines have potential protective effects in children and adolescents, but awareness is needed to monitor possible adverse effects after injection. Clinical trials of the COVID-19 vaccine in children and adolescents with long follow-up, large sample size, and different vaccines are still urgently needed.

Chest Computed Tomography for the Diagnosis of Patients with Coronavirus Disease 2019 (COVID-19): A Rapid Review and Meta-Analysis

BackgroundThe outbreak of the coronavirus disease 2019 (COVID-19) has had a massive impact on the whole world. Computed tomography (CT) has been widely used in the diagnosis of this novel pneumonia. This study aims to understand the role of CT for the diagnosis and the main imaging manifestations of patients with COVID-19. MethodsWe conducted a rapid review and meta-analysis on studies about the use of chest CT for the diagnosis of COVID-19. We comprehensively searched databases and preprint servers on chest CT for patients with COVID-19 between 1 January 2020 and 31 March 2020. The primary outcome was the sensitivity of chest CT imaging. We also conducted subgroup analyses and evaluated the quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. ResultsA total of 104 studies with 5694 patients were included. Using RT-PCR results as reference, a meta-analysis based on 64 studies estimated the sensitivity of chest CT imaging in COVID-19 was 99% (95% CI, 0.97-1.00). If case reports were excluded, the sensitivity in case series was 96% (95% CI, 0.93-0.99). The sensitivity of CT scan in confirmed patients under 18 years old was only 66% (95% CI, 0.11-1.00). The most common imaging manifestation was ground-glass opacities (GGO) which was found in 75% (95% CI, 0.68-0.82) of the patients. The pooled probability of bilateral involvement was 84% (95% CI, 0.81-0.88). The most commonly involved lobes were the right lower lobe (84%, 95% CI, 0.78-0.90) and left lower lobe (81%, 95% CI, 0.74-0.87). The quality of evidence was low across all outcomes. ConclusionsIn conclusion, this meta-analysis indicated that chest CT scan had a high sensitivity in diagnosis of patients with COVID-19. Therefore, CT can potentially be used to assist in the diagnosis of COVID-19.

Supportive Care for Patient with Respiratory Diseases: An Umbrella Review

BackgroundSupportive treatment is an important and effective part of the management for patients with life-threatening diseases. This study aims to identify and evaluate the forms of supportive care for patients with respiratory diseases. MethodsAn umbrella review of supportive care for patient respiratory diseases was undertaken. We comprehensively searched the following databases: Medline, EMBASE, Web of Science, CNKI (China National Knowledge Infrastructure), Wanfang Data and CBM (SinoMed) from their inception to 31 March 2020, and other sources to identify systematic reviews and meta-analyses related to supportive treatments for patient with respiratory diseases including COVID-19, SARS, MERS and influenza. We assessed the methodological quality using the AMSTAR score and the quality of the evidence for the primary outcomes of each included systematic review and meta-analysis. ResultsWe included 18 systematic reviews and meta-analyses in this study. Most studies focused on the respiratory and circulatory support. Ten studies were of high methodological quality, five studies of medium quality, and three studies of low quality. According to four studies extracorporeal membrane oxygenation did not reduce mortality in adults (OR/RR ranging from 0.71 to 1.28), but two studies reported significantly lower mortality in patients receiving venovenous extracorporeal membrane oxygenation than in the control group (OR/RR ranging from 0.38 to 0.73). Besides, monitoring of vital signs and increasing the number of medical staff may also reduce the mortality in patients with respiratory diseases. ConclusionsOur overview suggests that supportive care may reduce the mortality of patients with respiratory diseases to some extent. However, the quality of evidence for the primary outcomes in the included studies was low to moderate. Further systematic reviews and meta-analyses are needed to address the evidence gap regarding the supportive care for SARS, MERS and COVID-19.

Anti-depression mechanisms of Xiaoyao Powder based on fecal metabolomics / 中草药

Objective: To characterize the endogenous metabolites and metabolic changes of feces of chronic unpredictable mild stress (CUMS) rats by 1H-NMR, evaluate the improvement effects of Xiaoyao Powder and investigate the underlying mechanisms. Methods: The depression model was established by CUMS procedure. 1H-NMR coupled with multivariate statistical analysis was employed to reveal the changes of fecal metabolic profiles of CUMS rats and identify potential bio-markers involved in CUMS-induced depression. Based on the potential bio-markers, the relevant metabolic pathways were constructed. Results: A total of 10 metabolites was identified as potential bio-markers in fecal samples for the CUMS model. Compared with the control group, the contents of asparagine, aspartate, lactate and propionic acid in the CUMS rats were significantly increased (P < 0.05, 0.01), while phenylalanine, tyrosine, glutamate, glutamine, alanine and proline were significantly decreased (P < 0.05, 0.01). The administration of Xiaoyao Powder could significantly increase the levels of phenylalanine, tyrosine, glutamate, glutamine and proline, whereas reduced the levels of asparagine, lactate and propionic acid. Compared with the control group, six metabolic pathways were recognized as the most influenced pathways associated with the CUMS-induced depression: (1) aminoacyl-tRNA biosynthesis, (2) alanine, aspartate and glutamate metabolism, (3) arginine and proline metabolism, (4) glutamine and glutamate metabolism, (5) phenylalanine metabolism and (6) pyruvate metabolism. Among them, Xiaoyao Powder significantly mediated abnormalities of five pathways of (2), (3), (4), (5) and (6). Conclusion: It is the first report to investigate the antidepressant-like effects and underlying mechanisms of Xiaoyao Powder from the perspective of fecal metabolites. The current results showed that the anti-depression mechanisms of Xiaoyao Powder might be related to regulating the amino acid metabolism, glucose metabolism and intestinal microbial metabolism. This study provides a solid basis for revealing the anti-depression mechanisms of Xiaoyao Powder comprehensively and deeply.

Everyone has a donor: contribution of the Chinese experience to global practice of haploidentical hematopoietic stem cell transplantation / 医学前沿

Human leukocyte antigen (HLA)-matched donors for hematopoietic stem cell transplantation (HSCT) have long been scarce in China. Haploidentical (haplo) donors are available for the vast majority of patients, but toxicity has limited this approach. Three new approaches for haplo-HSCT originated from Italy, China, and USA in 1990 and have been developed to world-renowned system up to now. The Chinese approach have been greatly improved by implementing new individualized conditioning regimens, donor selection based on non-HLA systems, risk-directed strategies for graft-versus-host disease and relapse, and infection management. Haplo-HSCT has exhibited similar efficacy to HLA-matched HSCT and has gradually become the predominant donor source and the first alternative donor choice for allo-HSCT in China. Registry-based analyses and multicenter studies adhering to international standards facilitated the transformation of the unique Chinese experience into an inspiration for the refinement of global practice. This review will focus on how the new era in which "everyone has a donor" will become a reality in China.

Influence of collimator angle optimization on intensity-modulated radiotherapy planning for gastric cancer / 中华放射肿瘤学杂志

Objective To investigate the impact of four different collimator angle optimization techniques on the planning target volume (PTV) and organ at risk (OAR) during intensity-modulated radiotherapy (IMRT) for gastric cancer.Methods Ten patients with gastric cancer undergoing IMRT in Zhongnan Hospital of Wuhan University from 2015 to 2016 years were recruited in this study.All IMRT plans were designed by conventional five fields (330°,10°,45°,90°and 180°).In the Eclipse treatment planning system,four different collimator angle optimization techniques with consistent planning optimization parameters were employed to design the IMRT plan.Collimator angle optimization techniques included the following aspects.The collimator angle was set at 0 degree (CL0),collimator angle was set at 90 degree (CL90),Eclipse automatic collimator angle optimization (CLA) was adopted and collimator angle was set as the angle when the distance between X-Jaws and PTV (CLx) was the shortest.The dosimetric parameters mainly included the conformal index (CI) of PTV,the homogeneity index (HI),the mean dose (Mean),and the dosage of OAR.The treatment time (Time),monitor unit (MU),control point (CP),split field (SF) and conformal distance (Fx) were also considered.Results Regarding CL0 as the control,the CI,HI and Mean did not significantly differ among four collimator angle optimization techniques (all P＞0.05),whereas CLx could significantly increase the average dose of PTV in the target area (P＜0.05);CLx optimization reduced the liver (V30 reduction by 1.54％),left kidney (V12 decrease by 1.46％),right kidney and other OARs,whereas it slightly increased the maximum dose of the small intestine and spinal cord (＜1％).CLgo and CLA optimization elevated the dose of OAR in gastric cancer.Among four different collimator angle optimization techniques,CLx optimization reduced the MU (25.02％),CP (26.03％),Fx (20.27％) and SF (by 1.3separate fields on average) and treatment time (10.03％).CLgo and CLA optimization could decrease the MU,CP,Fx and SF.CL90 optimization had certain advantages in shortening the treatment time,whereas CLA optimization could prolong the treatment time by 5.04％.Conclusions During IMRT for gastric cancer,CL90,CLA and CLx collimator angle optimization techniques can obtain comparable dosimetry distribution to CL0 optimization technique,which can reduce the MU,decrease the radiation leakage,shorten the treatment time and improve treatment efficiency.

Meta-analysis on effect and safety of Yupingfeng Powder combined with antihistamines for chronic urticaria / 重庆医学

Objective To evaluate the effect and safetyof Yupingfeng Powdercombined with antihistamines for the treatment of patients with chronic urticaria.Methods Searched all randomized controlled trials (RCTs)of Yupingfeng Powder for treatment of chronic urticaria from the databases of CENTRAL,Pubmed,Embase,CNKI,CBM,VIP and Wanfang.Two researchers independently searched the literature and used the Cochrane system evaluation method to evaluate the quality of the study,and used RevMan 5.3 for meta-analysis.Results A total of 10 RCTs involving 964 patients were included in this study.Meta-analysis showed that compared with antihistamines alone,Yupingfeng Powder combined with antihistamines could improve the clinical effective rate (OR=2.83,95 ％ CI:1.89-4.25,P ＜ 0.01),reduce relapse rate (OR =0.13,95 ％ CI:0.07-0.24,P＜0.01) and reduce the incidence of adverse reactions (OR=0.40,95％CI:0.19-0.83,P=0.01).Conclusion Yupingfeng Powder combined with antihistamines has superior clinical effective rate,lower recurrence rate and incidence of adverse reactions.

Chinoketides A and B, Two New Antimicrobial Polyketides from the Endophytes of Distylium chinense with the “Black-Box” Co-culture Method

Two new polyketides, chinoketides A and B (1 – 2) with a known compound xylarphthalide A (3), were isolated from the solid medium of the endophytes from the leaves of the relic plant Distylium chinense with the “black-box” co-culture method, and the structures of two new compounds were elucidated by NMR, MS and CD spectra. And the absolute configurations of chinoketides A (1) and B (2) were determined as 2R,3R,8S and 5R,6S by calculating their ECD spectra to compare with the experimental CD spectra. Finally, the antimicrobial activities were evaluated to Erwinia carotovora sub sp. Carotovora (Jones) Bersey et al, and the results showed that compounds 1 – 3 displayed the antimicrobial activities with MIC value at 20.5, 30.4 and 10.2 µg/mL.

Role of Beclin 1 gene in autophagy and apoptosis of SW620 cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To study the role of Beclin1 gene in autophagy and apoptosis of SW620 cells.</p><p><b>METHODS</b>RNA interference was used to knockdown the expression of Beclin 1 in SW620 cells, and the cell viability was measured by MTT assays. The autophagic activity in serum-starved SW620 CRC cells was evaluated by assessing endogenous microtubule-associated protein 1 light chain 3 (LC3) protein levels using immunofluorescence assay. Flow cytometry was used to measure the apoptosis rate of SW620 cells treated with serum deprivation, staurosporine or etoposide, and the protein expression of Beclin1 was detected using Western blotting.</p><p><b>RESULTS</b>The viability of cells in pSUPER-Becl group was significantly reduced after serum deprivation (P<0.05). Serum deprivation for 24 h resulted in a stronger apoptotic resistance in cells in the control and pSUPER-non groups than in pSUPER-Becl group (P<0.05). Treatment with staurosporine the most significantly increased the cell apoptosis in pSUPER-Becl group (P<0.05), and similar effect was observed with etoposide treatment (P<0.05). As the time of serum deprivation extended, the expression of Beclin 1 in control group and pSUPER-non group increased progressively (P<0.05), which was consistent with the changes in LC3 expression; LC3 expression in pSUPER-Becl group decreased significantly with a prolonged serum starvation (P<0.05).</p><p><b>CONCLUSION</b>Beclin 1 is a crucial regulator of autophagy and apoptosis in colorectal cancer cells to maintain the balance between autophagy and apoptosis. Beclin 1 may serve as a protective mechanism to protect colorectal cancer cells from injury caused by low nutrition and chemotherapy byregulating cell autophagy.</p>

Role of Treg/Th17 cells and related cytokines in Graves' ophthalmopathy / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the role of CD4⁺ CD25⁺ Foxp3⁺ Treg/CD4⁺ IL-17A(+)Th17 cells and the related cytokines in Graves' ophthalmopathy.</p><p><b>METHODS</b>Based on clinical activity scores (CAS), we divided patients with untreated Graves' ophthal- mopathy into active group (AGO group with CAS ≥ 3 (15 cases) and non-active group (NGO group) with CAS<3 (15 cases), with another 15 patients with untreated Graves' disease free of eye symptoms (GD group) and 15 normal subjects as controls. Peripheral venous blood Treg/Th17 cell ratio was determined using flow cytometry. RT-PCR was used to detect the mRNA expression levels of Treg-specific transcription factor Foxp3 and Th17-specific transcription factor RORγt. Enzyme-linked immunosorbent assay (ELISA) was used to detect the serum levels of Th17 cell-related cytokines (IL-17A, IL-23, and IL-6) and Treg-related cytokines (TGF-β, IL-10, and IL-35).</p><p><b>RESULTS</b>Compared with the normal subjects, the patients in GD, NGO, AGO groups all showed significantly increased Th17 cell count (P<0.05), which was the highest in AGO group. RT-PCR results revealed significantly increased RORγt in GD, NGO, and AGO groups, also the highest in AGO group. Serum IL-17A, IL-23, and IL-6 levels all showed significant increments in GD, NGO, and AGO groups (P<0.05), especially in AGO group. Among the Treg-related cytokines, TGF-β and IL-35 levels decreased (P<0.05) but IL-10 increased significantly (P<0.05) in GD, NGO, AGO groups.</p><p><b>CONCLUSION</b>Decreased immunosuppressive capacity of Treg cells can be an important factor in the pathogenesis of Graves' ophthalmopathy. Th17 cells may also participate in the occurrence and progression of Graves' ophthalmopathy and can serve along with related cytokines as novel indicators of the disease activity. Impaired Treg/Th17 balance may importantly contribute to the occurrence of Graves' ophthalmopathy.</p>

Association of the ratio of regulatory and effector T cells with recurrence and chronic graft-versus-host disease after allogeneic hematopoietic stem cell transplantation / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate the association of the ratio of regulatory and effector T cells with recurrence and chronic graft-versus-host disease (cGVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT).</p><p><b>METHODS</b>Thirty patients with hematological malignancies who underwent allo-HSCT were classified as recurrence with cGVHD (n=4), non-recurrence with cGVHD (n=14), recurrence without cGVHD (n=5) and non-recurrence without cGVHD (n=7). The different percentage of CD4⁺CD25⁻CD69⁺ regulatory T cells in bone marrow and CD4⁺CD25⁺FoxP3⁺ regulatory T cells, Th1 cells and Th17 cells in peripheral blood were analyzed by flow cytometry.</p><p><b>RESULTS</b>There were no significant differences in all these T-cell subsets among different groups (P>0.05). While the ratio of CD4⁺CD25⁻CD69⁺ regulatory T cells and Th1 cells (0.211±0.177) in 9 recurrence patients was significant higher than that (0.133±0.160) in 21 non-recurrence patients (P=0.033). The ratio were also significance between recurrence without cGVHD and non-recurrence without cGVHD patients (0.167±0.073 vs 0.073±0.057, P=0.048), and between recurrence with cGVHD and non-recurrence without cGVHD patients (0.218±0.113 vs 0.073±0.057, P=0.024). Furthermore, the ratio of CD4⁺CD25⁺FoxP3⁺ regulatory T cells and Th17 cells was significant lower (1.975±2.045) in 18 cGVHD patients than that of 12 without cGVHD patients (3.198±1.132, P=0.010), and the ratio was also significant lower in non-recurrence patients with cGVHD (1.695±1.178) than that of without cGVHD (3.446±1.376, P=0.028).</p><p><b>CONCLUSION</b>Our results show that the ratio of CD4⁺CD25⁻CD69⁺ regulatory T cells and Th1 cells raise in recurrence patients, and the ratio of CD4⁺CD25⁺FoxP3⁺ regulatory T cells and Th17 decrease in cGVHD patients, which suggest that the ratio of regulatory and effector T cells had association with recurrence and cGVHD in patients with allo-HSCT.</p>

Reconstitution kinetics of T helper cells subsets post unmanipulated allogeneic blood and marrow transplantation / 中华血液学杂志

<p><b>OBJECTIVE</b>To compare the differences of the T helper cell reconstitution kinetics between HLA matched or HLA mismatched allo-HSCT through exploring the reconstitution kinetics of CD4+ CD25+Foxp3+ cells (CD4+ Treg), CD8+CD25+Foxp3+ cells (CD8+Treg), CD4+CD25-CD127+ conventional T cells (Tcon) and the secretion of IL-17a and IFN-γ in CD4+ T cells (Th17 and Th1 cells) or CD8+ T cells (Tc17 and Tc17 cells) post allogeneic hematopoietic stem cells transplantation (allo-HSCT).</p><p><b>METHODS</b>From December 2011 to October 2012, the peripheral blood (PB) of 20 patients undergoing HLA matched (10 patients) or mismatched (10 patients) allo- HSCT without acute graft-versus-host disease (aGVHD) and of 10 related healthy donors were collected to analyze the expression of CD25+Foxp3+, IL-17a, IFN-γ and CD127 expression through 8-colour Flow cytometer.</p><p><b>RESULTS</b>(1) The reconstitution kinetics of CD3+ T cells, CD4+ T cells, CD8+ T cells absolute numbers were comparable within 2 month post HLA matched and mismatched transplantation. (2)The absolute numbers of CD4+ Treg cells[+30 d, 8.46 (0.36-27.41) cells/μl 1.10 (0.04-8.03) cells/μl, P<0.05; +60 d, 8.50 (1.16-36.20) cells/μl vs 2.73 (0.34-6.84) cells/μl, P<0.05], Tcon cells[+30 d, 72.69 (3.85-211.73) cells/μl vs 13.41 (0.48-96.17) cells/μl, P<0.05; +60 d, 100.85 (16.28-267.20) cells/μl vs 47.75 (6.34-143.04) cells/μl, P<0.05], as well as Th17 cells[+30 d, 2.34 (0.02-6.87) cells/μl vs 0.20 (0.02-1.34) cells/μl, P<0.05; + 60 d, 1.90 (0.36- 7.82) cells/μl vs 0.46 (0.03-1.39) cells/μl, P<0.05]and Tc17 cells[+ 30 d, 1.08 (0.07-15.03) cells/μl vs 0.25 (0.01- 0.81) cells/μl, P<0.05;+60 d, 1.85 (0.63-26.57) cells/μl vs 0.46 (0.01-3.66) cells/μl, P<0.05]within 2 month post HLA matched HSCT were significantly higher than those post HLA- mismatched HSCT. However, the absolute numbers of Th1 cells or Tc1 cells within 2 month post HLA-matched or HLA-mismatched HSCT were comparable. (3) The ratio of Th1 and Th17 cells, or the ratio of Tc1 and Tc17 cells were significantly higher within 2 month post HLA-mismatched allo-HSCT compared to those post HLA-matched HSCT.</p><p><b>CONCLUSION</b>The reconstitution kinetics of T helper cells subset were different at early stage post HLA-matched or HLA-mismatched allo-HSCT, which might be help to explain the different rate or the different involved organ of the acute graft-versus-host diseases (aGVHD) post HLA-matched or -mismatched allo-HSCT.</p>

Coracoclavicular screw fixation for treatment of unstable distal clavicle fractures / 中国矫形外科杂志

[Objective]To retrospectively analyze of functional and radiographic outcome of distal calvicle fractures (Neer type II) treated with coracoclavicular screw fixation.[Method]Fifteen patients with Neer type II distal clavicle fracture were treated surgically between March 2001 and March 2004.Operative treatment included open reduction and fixation of the proximal clavicular fragment to the coracoid process using a 6.5-mm cancellous screw and repair of the coracoclavicular ligaments.Perioperative radiographs were performed to ensure that the screw was introduced properly into the coracoid.Following the operation,the arm was placed in a sling for two weeks.After two weeks,the sling was discontinued and the patient was permitted to use the arm for daily activities except for lifting,pulling,and pushing for 6 weeks.The patient is instructed not to perform any heavy lifting,pushing,pulling or participate in contact sports for 3 months.Data were collected to allow scoring according to the American Shoulder and Elbow Surgeons shoulder index 6 months after operation.[Result]All the patients were followed up at an average of 16 months (range:9~26 months).Fracture union occurred at a mean of 7 weeks (range:6~9 weeks)postoperatively without any serious complications such as screw-migration,pseudarthrosis,infection,neurovascular damage,or skin necrosis.All patients returned to the pre-injury level of activity with no residual pain or dysfunction.The mean American Shoulder and Elbow Surgeons shoulder index was 97 points ( range: 90-100 points) 6 months after operation.Two patients showed radiologically ossification of the acromioclavicular joint with no clinical symptoms.[Conclusion]Coracoclavicular screw fixation is a relatively simple,reliable,and safe technique of open reduction and internal fixation of the type II distal clavicle fracture.

Morphology study of freeze-drying mononuclear cells of human cord blood.

The research on haematopoietic stem cells of human cord blood has become more important recently. At present, cord blood is mainly preserved at ultra-low temperatures. In the former study, we compared the effects of preserving mononuclear cells (MNC) and whole human cord blood by freeze-drying. This time, a further study was conducted on freeze-drying mononuclear cells. Samples in the presence of PVP, sucrose, mannitol and FBS were firstly frozen to -38 degrees C. Afterwards, they were vacuum-dried at a selected shelf temperature of -30 degrees C for the main drying stage, and then vacuum-dried at 15 degrees C for the second drying stage. The entire time of freeze-drying process was 41 hours. Samples were stored at room temperature for 7 days prior to evaluation. Subsequently, the dried samples were resuspended in an isotonic phosphate-buffered saline solution. The residual moisture content was 6.5 +/- 0.87%. The recovery of the cells was tested by a haemacytometer, and the numerical cell count recovery of rehydrated MNC increased by 8%. Morphology of the fresh and rehydrated MNC was analyzed respectively using standard light microscopy, scanning electron microscope and transmission electron microscope. The results showed that karyons changed and cytoplasm decreased after rehydration, but it is still unknown that whether these changes will influence the proliferative ability of the stem cells.

Freeze-drying of mononuclear cells and whole blood of human cord blood.

The research on haematopoietic stem cells of human cord blood has become more important recently. People have concentrated on the preservation of cord blood stem cells. At present, cord blood can be preserved at ultra-low temperatures. In this study, we try to preserve cord blood and its constituents by freeze-drying. The experiments on both the mononuclear cell content and the whole blood of human cord blood were carried out respectively. The samples were frozen firstly by different cooling protocols in the presence of PVP, sucrose, and mannitol. Afterwards, they were vacuum-dried at a selected shelf temperature of -30 degree C for the main drying stage, and then vacuum-dried at 15 degree C for the second drying stage. The entire time of the freeze drying was 52 hours. Samples were stored at room temperature for 2 days prior to evaluation. Subsequently, the dried samples were suspended in an isotonic phosphate-buffered saline solution. The recovery of the cells were tested by a haemacytometer, and the highest cell numerical count recovery of MNC was 75.0 percent (SD = 4.1 percent) (P = 0.01), obtained in the protocol of 40 percent PVP + 20 percent sucrose + 10 percent Mannitol. The viability of the nucleated cells measured by PI staining and the ratio of the number of CD34+ to the number of lymphocytes (by the FITC anti-human CD34+ conjugated antibody method) were measured using a flow cytometer (FCM). The protocol of 40 percent PVP + 20 percent sucrose + 10 percent fetal bovine serum had the highest viability of 98.6 percent (SD = 0.7 percent) (P = 0.01). The highest ratio of CD34+ to lymphocytes was 1.2%, and the highest recovery of CD34+ was 68.4 percent (SD = 39.5 percent) (P = 0.05). Comparing the results of the lyophilized MNC subfraction with that of the whole blood, the lyophilization of the isolated MNC was more successful than that of whole blood.