Umbilical Cord Blood Testosterone and Childhood Internalizing and Externalizing Behavior: A Prospective Study

Antenatal testosterone exposure influences fetal neurodevelopment and gender-role behavior in postnatal life and may contribute to differences in developmental psychopathology during childhood. We prospectively measured the associations between umbilical cord blood testosterone levels at birth and childhood behavioral development in both males and females from a large population based sample. The study comprised 430 females and 429 males from the Western Australian Pregnancy Cohort (Raine) Study where umbilical cord blood had been collected. Total testosterone concentrations were determined by mass spectrometry and bioavailable testosterone (BioT) levels were calculated. At two, five, eight and ten years of age, the participants completed the Child Behavior Checklist (CBCL). Linear regression models were used to analyse the relationship between BioT concentrations (in quartiles) and CBCL scores (total, internalizing, externalizing and selected syndrome). Boys had higher mean CBCL T-scores than girls across all ages of follow-up. There was no significant relationship between cord blood BioT quartiles and CBCL total, internalizing and externalizing T-scores at age two or five to ten combined. In the syndrome score analyses, higher BioT quartiles were associated with significantly lower scores for attention problems for boys at age five, eight and ten, and greater withdrawal symptoms in pre-school girls (age five). We did not identify a consistent relationship between antenatal testosterone exposure and total, internalizing or externalizing behavioral difficulties in childhood. Higher umbilical cord BioT levels were associated with lower scores for attention problems in boys up to 10 years and more withdrawn behavior in 5-year-old girls; however, these findings were not consistent across ages and require further investigation in a larger sample.     

Risk Factors for Severe Neonatal Hyperbilirubinemia in Low and Middle-Income Countries: A Systematic Review and Meta-Analysis

BackgroundAvailable evidence suggests that low- and middle-income countries (LMICs) bear the greatest burden of severe neonatal hyperbilirubinemia characterized by disproportionately high rates of morbidity, mortality and neurodevelopmental disorders compared to high-income countries. We set out to identify the risk factors that contribute to the burden of severe hyperbilirubinemia in the most developmentally disadvantaged LMICs to highlight areas for action and further research.MethodsWe systematically searched PubMed, Scopus, Ovid EMBASE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), WHO Library Database (WHOLIS), African Index Medicus (AIM), African Journals Online (AJOL), LILACS, and IndMed for reports published between January 1990 and June 2014. We included only studies that controlled for the effects of confounding variables in determining maternal and infant risk factors for severe hyperbilirubinemia. We conducted meta-analysis of the eligible studies and computed the summary risk estimates with random effects models.ResultsA total of 13 studies with 1,951 subjects and 32,208 controls from India, Nigeria, Pakistan, Nepal and Egypt were identified and analyzed. The pooled data showed that primiparity (OR, 1.59; 95% CI:1.26-2.00), delivery outside public hospitals (OR, 6.42; 95% CI:1.76-23.36), ABO incompatibility (OR, 4.01; 95% CI:2.44-6.61), Rhesus hemolytic disease (OR, 20.63; 95% CI:3.95-107.65), G6PD deficiency (OR, 8.01; 95% CI:2.09-30.69), UGT1A1 polymorphisms (OR, 4.92; 95% CI:1.30-18.62), low gestational age (OR, 1.71; 95% CI:1.40-2.11), underweight/weight loss (OR, 6.26; 95% CI:1.23-31.86), sepsis (OR, 9.15; 95% CI:2.78-30.10) and high transcutaneous/total serum bilirubin levels (OR, 1.46; 95% CI:1.10-1.92) placed infants at increased risk of severe hyperbilirubinemia or bilirubin induced neurologic dysfunctions. Low social class was not associated with an increased risk of severe hyperbilirubinemia.ConclusionsInfants at risk of severe hyperbilirubinemia in LMICs are associated with maternal and neonatal factors that can be effectively addressed by available interventions to curtail the disease burden prevailing in the affected countries.     

Heliotherapy for Neonatal Hyperbilirubinemia in Southwest,Nigeria: A Baseline Pre-Intervention Study

Background

A novel filtered-sunlight phototherapy (FSPT) device has been demonstrated to be safe and efficacious for treating infants with neonatal jaundice in resource-constrained tropical settings. We set out to provide baseline data for evaluating the clinical impact of this device in a referral pediatric hospital.

Methods

We reviewed the medical records of infants admitted for neonatal hyperbilirubinemia in an inner-city Children’s Hospital in Lagos, between January 2012 and December 2014 to determine the pattern, treatment and outcomes during the pre-intervention period. Factors associated with adverse outcomes were identified through multivariable logistic regression.

Results

Of the 5,229 neonatal admissions over the period, a total of 1,153 (22.1%) were admitted for neonatal hyperbilirubinemia. Complete records for 1,118 infants were available for analysis. The incidence of acute bilirubin encephalopathy (ABE) and exchange transfusion (ET) were 17.0% (95% CI: 14.9%–19.3%) and 31.5% (95% CI: 28.8%–34.3%) respectively. A total of 61 (5.5%, 95% CI: 4.3%–6.9%) of the jaundiced infants died. Weight on admission, peak total serum bilirubin (TSB), sepsis and exposure to hemolytic products were predictive of ABE, while age on admission, peak TSB, ABO incompatibility and ABE were predictive of ET. Rhesus incompatibility, asphyxia, exposure to hemolytic substances and ABE were associated with elevated mortality risk, while ET was a protective factor. Lack of routine irradiance monitoring and steady energy supply were frequent challenges for conventional blue-light phototherapy.

Conclusions

Severe hyperbilirubinemia is associated with high rates of ABE and ET in this setting, and remains a significant contributor to neonatal admissions and mortality. To be impactful, FSPT, complemented with improved diagnostic facilities, should effectively curtail jaundice-related adverse outcomes in this and comparable settings.     

Neonatal Bacteriuria: A Prospective Study in 1,460 Infants

In a prospective study of 1,460 virtually consecutive neonates 14 (1%) were found to have bacteriuria, established by bladder puncture. Eleven were boys and three girls. Five of the infants with bacteriuria had symptoms suggestive of infection and were treated with antibiotics. The remaining nine were asymptomatic and remained so during a period of observation—five cleared their urine of bacteria without treatment, and four received antibiotics. Only one infant with bacteriuria had bacteraemia. Six infants had more than 10 white blood cells per mm³ in the bladder puncture urine and three had proteinuria. The blood urea was slightly raised in only two of the infants. The intravenous pyelogram was normal in all infants with bacteriuria but eight had slight or moderate vesicoureteric reflux when examined by micturating cystourethrography.     

脐带血红细胞MCV和MCH筛查新生儿地中海贫血的可行性研究

探讨脐带血MCV(红细胞平均体积)和MCH(红细胞平均血红蛋白含量)筛查新生儿地中海贫血的可行性,确定MCV和MCH最佳临界值。采集来自广东省21个不同地区13 396例新生儿脐带血样本。应用标准全自动血细胞分析仪对新生儿脐带血进行全血细胞分析,采用液相芯片技术对脐带血进行基因验证。应用统计学方法计算出灵敏度和特异度,使用ROC曲线(受试者特征工作曲线)确定MCV、MCH的最佳截断值。结果发现携带地中海贫血基因的脐带血中MCV、MCH值下降,它们可以作为新生儿地中海贫血的筛查指标。α-地中海贫血、β-地中海贫血,以及αβ-复合型地中海贫血的截断值分别为104 fl/34 pg;110 fl/36 pg;104 fl/33pg。根据我们的结果,MCV和MCH有较高的灵敏度和特异度。同时,应用MCV、MCH两项指标筛查不同类型的地贫患儿时,诊断符合率较高。此外,MCV、MCH的ROC曲线下面积较大,特异度和灵敏度高,筛查效果好。可以得出的结论:广东省新生儿地中海贫血发病率高,MCV和MCH应用于新生儿地中海贫血的早期诊断具有重要价值。     

The Metabolomic Profile of Umbilical Cord Blood in Neonatal Hypoxic Ischaemic Encephalopathy

Background

Hypoxic ischaemic encephalopathy (HIE) in newborns can cause significant long-term neurological disability. The insult is a complex injury characterised by energy failure and disruption of cellular homeostasis, leading to mitochondrial damage. The importance of individual metabolic pathways, and their interaction in the disease process is not fully understood. The aim of this study was to describe and quantify the metabolomic profile of umbilical cord blood samples in a carefully defined population of full-term infants with HIE.

Methods and Findings

The injury severity was defined using both the modified Sarnat score and continuous multichannel electroencephalogram. Using these classification systems, our population was divided into those with confirmed HIE (n = 31), asphyxiated infants without encephalopathy (n = 40) and matched controls (n = 71). All had umbilical cord blood drawn and biobanked at −80°C within 3 hours of delivery. A combined direct injection and LC-MS/MS assay (AbsolutIDQ p180 kit, Biocrates Life Sciences AG, Innsbruck, Austria) was used for the metabolomic analyses of the samples. Targeted metabolomic analysis showed a significant alteration between study groups in 29 metabolites from 3 distinct classes (Amino Acids, Acylcarnitines, and Glycerophospholipids). 9 of these metabolites were only significantly altered between neonates with Hypoxic ischaemic encephalopathy and matched controls, while 14 were significantly altered in both study groups. Multivariate Discriminant Analysis models developed showed clear multifactorial metabolite associations with both asphyxia and HIE. A logistic regression model using 5 metabolites clearly delineates severity of asphyxia and classifies HIE infants with AUC = 0.92. These data describe wide-spread disruption to not only energy pathways, but also nitrogen and lipid metabolism in both asphyxia and HIE.

Conclusion

This study shows that a multi-platform targeted approach to metabolomic analyses using accurately phenotyped and meticulously biobanked samples provides insight into the pathogenesis of perinatal asphyxia. It highlights the potential for metabolomic technology to develop a diagnostic test for HIE.     

Cobalamin Analogues in Humans: A Study on Maternal and Cord Blood

Background

Haptocorrin (HC) carries cobalamin analogues (CorA), but whether CorA are produced in the body is unknown. All cobalamins (Cbl) to the foetus are delivered by the Cbl-specific protein transcobalamin (TC), and therefore analysis of cord serum for CorA may help to clarify the origin of CorA.

Methods

HC-CorA were quantified in paired samples of cord serum from newborns and serum from mothers (n = 69).

Results

The CorA-concentration was higher in cord serum (median = 380, range: 41–780 pmol/L) than in serum from the mothers (median = 160, range: 64–330 pmol/L), (p<0.0001). HPLC-analysis showed CorA-peaks with retention times of 13.5, 14,5 and 16.5 min in samples from both the mother and cord serum. The peak with retention time 16.5 min constituted 24% (mother) and 45% (cord serum) of the total amount CorA, and eluted as does dicyanocobinamide.

Conclusion

Our results support that CorA in the human body are derived from Cbl.     

Antioxidant Lactobacilli Could Protect Gingival Fibroblasts Against Hydrogen Peroxide: A Preliminary In Vitro Study

Oxidative stress and tissue destruction are at the heart of periodontal diseases. The dental research area is geared toward the prevention of free radicals by nutrient antioxidants. Lactic acid bacteria (LAB) have recently attracted attention in alternative dental therapies. We aimed at highlighting the antioxidative property of Lactobacilli and Bifidobacterium strains and at determining their protective effect on gingival fibroblasts (GFs). Two Lactobacilli and 2 Bifidobacterium strains were screened for their exopolysaccharide (EPSs) production. Antioxidative assays were conducted by spectrophotometer analysis. Resistance to different concentrations of hydrogen peroxide (H₂O₂) was determined by the serial dilution technique. The protective effect of strains on GFs on hydrogen peroxide exposure was also examined by a new trypan blue exclusion assay method. Bifidobacterium breve A28 showed the highest EPS production (122 mg/l) and remarkable antioxidant activity, which were demonstrated by its ability to scavenge 72 % α,α-diphenyl-1-picrylhydrazyl free radical and chelate 88 % of iron ion, respectively. Inhibition of lipid peroxidation was determined as 71 % for the A28 strain. We suggest that LAB with antioxidative activity could be a good natural therapy agent for periodontal disorders.     

Etiology of Severe Non-malaria Febrile Illness in Northern Tanzania: A Prospective Cohort Study

Introduction

The syndrome of fever is a commonly presenting complaint among persons seeking healthcare in low-resource areas, yet the public health community has not approached fever in a comprehensive manner. In many areas, malaria is over-diagnosed, and patients without malaria have poor outcomes.

Methods and Findings

We prospectively studied a cohort of 870 pediatric and adult febrile admissions to two hospitals in northern Tanzania over the period of one year using conventional standard diagnostic tests to establish fever etiology. Malaria was the clinical diagnosis for 528 (60.7%), but was the actual cause of fever in only 14 (1.6%). By contrast, bacterial, mycobacterial, and fungal bloodstream infections accounted for 85 (9.8%), 14 (1.6%), and 25 (2.9%) febrile admissions, respectively. Acute bacterial zoonoses were identified among 118 (26.2%) of febrile admissions; 16 (13.6%) had brucellosis, 40 (33.9%) leptospirosis, 24 (20.3%) had Q fever, 36 (30.5%) had spotted fever group rickettsioses, and 2 (1.8%) had typhus group rickettsioses. In addition, 55 (7.9%) participants had a confirmed acute arbovirus infection, all due to chikungunya. No patient had a bacterial zoonosis or an arbovirus infection included in the admission differential diagnosis.

Conclusions

Malaria was uncommon and over-diagnosed, whereas invasive infections were underappreciated. Bacterial zoonoses and arbovirus infections were highly prevalent yet overlooked. An integrated approach to the syndrome of fever in resource-limited areas is needed to improve patient outcomes and to rationally target disease control efforts.     

Risk Prediction Score for Severe High Altitude Illness: A Cohort Study

Background

Risk prediction of acute mountain sickness, high altitude (HA) pulmonary or cerebral edema is currently based on clinical assessment. Our objective was to develop a risk prediction score of Severe High Altitude Illness (SHAI) combining clinical and physiological factors. Study population was 1017 sea-level subjects who performed a hypoxia exercise test before a stay at HA. The outcome was the occurrence of SHAI during HA exposure. Two scores were built, according to the presence (PRE, n = 537) or absence (ABS, n = 480) of previous experience at HA, using multivariate logistic regression. Calibration was evaluated by Hosmer-Lemeshow chisquare test and discrimination by Area Under ROC Curve (AUC) and Net Reclassification Index (NRI).

Results

The score was a linear combination of history of SHAI, ventilatory and cardiac response to hypoxia at exercise, speed of ascent, desaturation during hypoxic exercise, history of migraine, geographical location, female sex, age under 46 and regular physical activity. In the PRE/ABS groups, the score ranged from 0 to 12/10, a cut-off of 5/5.5 gave a sensitivity of 87%/87% and a specificity of 82%/73%. Adding physiological variables via the hypoxic exercise test improved the discrimination ability of the models: AUC increased by 7% to 0.91 (95%CI: 0.87–0.93) and 17% to 0.89 (95%CI: 0.85–0.91), NRI was 30% and 54% in the PRE and ABS groups respectively. A score computed with ten clinical, environmental and physiological factors accurately predicted the risk of SHAI in a large cohort of sea-level residents visiting HA regions.     

A Multi-Center Prospective Derivation and Validation of a Clinical Prediction Tool for Severe Clostridium difficile Infection

Background and Aims

Prediction of severe clinical outcomes in Clostridium difficile infection (CDI) is important to inform management decisions for optimum patient care. Currently, treatment recommendations for CDI vary based on disease severity but validated methods to predict severe disease are lacking. The aim of the study was to derive and validate a clinical prediction tool for severe outcomes in CDI.

Methods

A cohort totaling 638 patients with CDI was prospectively studied at three tertiary care clinical sites (Boston, Dublin and Houston). The clinical prediction rule (CPR) was developed by multivariate logistic regression analysis using the Boston cohort and the performance of this model was then evaluated in the combined Houston and Dublin cohorts.

Results

The CPR included the following three binary variables: age ≥ 65 years, peak serum creatinine ≥2 mg/dL and peak peripheral blood leukocyte count of ≥20,000 cells/μL. The Clostridium difficile severity score (CDSS) correctly classified 76.5% (95% CI: 70.87-81.31) and 72.5% (95% CI: 67.52-76.91) of patients in the derivation and validation cohorts, respectively. In the validation cohort, CDSS scores of 0, 1, 2 or 3 were associated with severe clinical outcomes of CDI in 4.7%, 13.8%, 33.3% and 40.0% of cases respectively.

Conclusions

We prospectively derived and validated a clinical prediction rule for severe CDI that is simple, reliable and accurate and can be used to identify high-risk patients most likely to benefit from measures to prevent complications of CDI.     

Risk Prediction of Emergency Department Revisit 30 Days Post Discharge: A Prospective Study

BackgroundAmong patients who are discharged from the Emergency Department (ED), about 3% return within 30 days. Revisits can be related to the nature of the disease, medical errors, and/or inadequate diagnoses and treatment during their initial ED visit. Identification of high-risk patient population can help device new strategies for improved ED care with reduced ED utilization.ConclusionsOur ED 30-day revisit model was prospectively validated on the Maine State HIN secure statewide data system. Future integration of our ED predictive analytics into the ED care work flow may lead to increased opportunities for targeted care intervention to reduce ED resource burden and overall healthcare expense, and improve outcomes.     

Incidence and Prediction of Falls in Dementia: A Prospective Study in Older People

Background

Falls are a major cause of morbidity and mortality in dementia, but there have been no prospective studies of risk factors for falling specific to this patient population, and no successful falls intervention/prevention trials. This prospective study aimed to identify modifiable risk factors for falling in older people with mild to moderate dementia.

Methods and Findings

179 participants aged over 65 years were recruited from outpatient clinics in the UK (38 Alzheimer''s disease (AD), 32 Vascular dementia (VAD), 30 Dementia with Lewy bodies (DLB), 40 Parkinson''s disease with dementia (PDD), 39 healthy controls). A multifactorial assessment of baseline risk factors was performed and fall diaries were completed prospectively for 12 months. Dementia participants experienced nearly 8 times more incident falls (9118/1000 person-years) than controls (1023/1000 person-years; incidence density ratio: 7.58, 3.11–18.5). In dementia, significant univariate predictors of sustaining at least one fall included diagnosis of Lewy body disorder (proportional hazard ratio (HR) adjusted for age and sex: 3.33, 2.11–5.26), and history of falls in the preceding 12 months (HR: 2.52, 1.52–4.17). In multivariate analyses, significant potentially modifiable predictors were symptomatic orthostatic hypotension (HR: 2.13, 1.19–3.80), autonomic symptom score (HR per point 0–36: 1.055, 1.012–1.099), and Cornell depression score (HR per point 0–40: 1.053, 1.01–1.099). Higher levels of physical activity were protective (HR per point 0–9: 0.827, 0.716–0.956).

Conclusions

The management of symptomatic orthostatic hypotension, autonomic symptoms and depression, and the encouragement of physical activity may provide the core elements for the most fruitful strategy to reduce falls in people with dementia. Randomised controlled trials to assess such a strategy are a priority.     

Prediction of Recurrent Venous Thromboembolism by Clot Lysis Time: A Prospective Cohort Study

Venous thromboembolism (VTE) is a chronic disease, which tends to recur. Whether an abnormal fibrinolytic system is associated with an increased risk of VTE is unclear. We assessed the relationship between fibrinolytic capacity (reflected by clot lysis time [CLT]) and risk of recurrent VTE. We followed 704 patients (378 women; mean age 48 yrs) with a first unprovoked VTE for an average of 46 months after anticoagulation withdrawal. Patients with natural coagulation inhibitor deficiency, lupus anticoagulant, cancer, homozygosity for factor V Leiden or prothrombin mutation, or requirement for indefinite anticoagulation were excluded. Study endpoint was symptomatic recurrent VTE. For measurement of CLT, a tissue factor-induced clot was lysed by adding tissue-type plasminogen activator. Time between clot formation and lysis was determined by measuring the turbidity.135 (19%) patients had recurrent VTE. For each increase in CLT of 10 minutes, the crude relative risk (RR) of recurrence was 1.13 (95% CI 1.02–1.25; p = 0.02) and was 1.08 (95% CI 0.98–1.20; p = 0.13) after adjustment for age and sex. For women only, the adjusted RR was 1.14 (95% CI, 0.91–1.42, p = 0.22) for each increase in CLT of 10 minutes. CLT values in the 4^th quartile of the female patient population, as compared to values in the 1^st quartile, conferred a risk of recurrence of 3.28 (95% CI, 1.07–10.05; p = 0.04). No association between CLT and recurrence risk was found in men. Hypofibrinolysis as assessed by CLT confers a moderate increase in the risk of recurrent VTE. A weak association between CLT and risk of recurrence was found in women only.     

双氧水介导制备对硝基苯甲酸乙酯的初步研究

目的:探讨双氧水催化合成对硝基苯甲酸乙酯的可行性,并考察了反应物的摩尔比、催化剂用量、反应温度及反应时间对产物收率的影响.方法:分别采用单因素设计实验与正交设计实验,分析比较这两种方法的最佳反应条件.采用数字熔点仪测定样品的熔点:用GC112A型气相色谱仪测定了产物的纯度;用傅里叶变换红外光谱仪测定产物的结构.结果:双氧水可以作为合成对硝基苯甲酸乙酯的催化剂.综合分析可知:当无水乙醇和对硝基苯甲酸的摩尔比为4:1,催化剂含量为10%,反应温度为80℃,反应时间为2.5-3h时酯化产率可达到最高值.结论:双氧水催化对硝基苯甲酸、无水乙醇合成对硝基苯甲酸乙酯的效率较高,产品纯度高,环境污染小,不失为一种新的合成方法.     

Clinical Outcomes and Microbiological Characteristics of Severe Pneumonia in Cancer Patients: A Prospective Cohort Study

Introduction

Pneumonia is the most frequent type of infection in cancer patients and a frequent cause of ICU admission. The primary aims of this study were to describe the clinical and microbiological characteristics and outcomes in critically ill cancer patients with severe pneumonia.

Methods

Prospective cohort study in 325 adult cancer patients admitted to three ICUs with severe pneumonia not acquired in the hospital setting. Demographic, clinical and microbiological data were collected.

Results

There were 229 (71%) patients with solid tumors and 96 (29%) patients with hematological malignancies. 75% of all patients were in septic shock and 81% needed invasive mechanical ventilation. ICU and hospital mortality rates were 45.8% and 64.9%. Microbiological confirmation was present in 169 (52%) with a predominance of Gram negative bacteria [99 (58.6%)]. The most frequent pathogens were methicillin-sensitive S. aureus [42 (24.9%)], P. aeruginosa [41(24.3%)] and S. pneumonia [21 (12.4%)]. A relatively low incidence of MR [23 (13.6%)] was observed. Adequate antibiotics were prescribed for most patients [136 (80.5%)]. In multivariate analysis, septic shock at ICU admission [OR 5.52 (1.92–15.84)], the use of invasive MV [OR 12.74 (3.60–45.07)] and poor Performance Status [OR 3.00 (1.07–8.42)] were associated with increased hospital mortality.

Conclusions

Severe pneumonia is associated with high mortality rates in cancer patients. A relatively low rate of MR pathogens is observed and severity of illness and organ dysfunction seems to be the best predictors of outcome in this population.     

Alterations in Cortical Sensorimotor Connectivity following Complete Cervical Spinal Cord Injury: A Prospective Resting-State fMRI Study

Functional magnetic resonance imaging (fMRI) studies have demonstrated alterations during task-induced brain activation in spinal cord injury (SCI) patients. The interruption to structural integrity of the spinal cord and the resultant disrupted flow of bidirectional communication between the brain and the spinal cord might contribute to the observed dynamic reorganization (neural plasticity). However, the effect of SCI on brain resting-state connectivity patterns remains unclear. We undertook a prospective resting-state fMRI (rs-fMRI) study to explore changes to cortical activation patterns following SCI. With institutional review board approval, rs-fMRI data was obtained in eleven patients with complete cervical SCI (>2 years post injury) and nine age-matched controls. The data was processed using the Analysis of Functional Neuroimages software. Region of interest (ROI) based analysis was performed to study changes in the sensorimotor network using pre- and post-central gyri as seed regions. Two-sampled t-test was carried out to check for significant differences between the two groups. SCI patients showed decreased functional connectivity in motor and sensory cortical regions when compared to controls. The decrease was noted in ipsilateral, contralateral, and interhemispheric regions for left and right precentral ROIs. Additionally, the left postcentral ROI demonstrated increased connectivity with the thalamus bilaterally in SCI patients. Our results suggest that cortical activation patterns in the sensorimotor network undergo dynamic reorganization following SCI. The presence of these changes in chronic spinal cord injury patients is suggestive of the inherent neural plasticity within the central nervous system.     

脐带血干细胞的低温保存研究

脐带血干细胞在医学上具有广阔的应用前景.本文对其低温保存进行了理论和实验研究.在以5%和10%的二甲亚砜做低温保护剂时,实验得到干细胞分别在冷却速率为10℃/min和10.5℃/min时细胞具有最高的存活率,与理论预测的最佳冷却速率十分接近.