烧伤早期血清CRP、C_3、T_f、PA变化及临床意义

为探索烧伤早期血清急性期蛋白的变化规律及其临床意义，将３２例烧伤病人按烧伤总面积大小分为小于２０％，２０％～５０％和大于５０％三组。于伤后８，２４，４８，７２小时采血，组３加测伤后７，１４，２１天三个时相点以观察与感染的关系。以免疫速率散射浊度法测定ＣＲＰ，Ｃ３，Ｔｆ用琼脂扩散法，ＰＡ用火箭免疫电泳法测定。结果表明：伤后４８～７２小时血清ＣＲＰ达到高峰（Ｐ＜０．０１）；伤后８小时Ｃ３显著下降（Ｐ＜０．０５），２４小时达最低值，Ｃ３下降与ＣＲＰ升高无相关性（ｒ＝０．０８８５，Ｐ＞０．０５）；４８小时Ｔｆ显著下降（Ｐ＜０．０１），ＰＡ与Ｔｆ变化相似。感染及脓毒症发生时各监测指标变化不显著。提示：①ＣＲＰ的变化主要反映组织损伤的程度而不能预示脓毒症的易感性；②Ｃ３下降并非ＣＲＰ升高引起。Ｔｆ下降有利于细菌生长。     

血清心肌肌球蛋白轻链Ⅰ测定在烧伤后心肌损伤诊断中的应用

采用３０％Ⅲ度烧伤大鼠模型，动态检测了伤前及烧伤后血清心肌肌球蛋白轻链Ⅰ（ＣＭＬＣ１）含量及心肌酶谱（ＣＫ，ＡＳＴ和ＬＤＨ）变化，以进行烧伤后心肌损伤的评价。结果表明ＣＭＬＣ１在烧伤后１小时即明显增高，以后持续增高，伤后１２小时比对照值升高约２０倍，至伤后２４，４８小时仍保持高水平，伤后７２小时开始轻度下降。心肌酶谱则于伤后３小时开始显著升高，至伤后２４，４８小时已表现出明显下降的趋势，伤后７２小时已接近对照水平。提示：ＣＭＬＣ１迅速大幅度增高表明严重烧伤早期心肌即发生明显损伤，ＣＭＬＣ１与心肌酶谱比较具有出现早、高敏感、高特异等特点，是评价烧伤后心肌损伤的一个可靠指标。     

血清心肌肌球蛋白轻链I测定在烧伤后心肌损伤诊断中的应用

采用３０％Ⅲ度烧伤大鼠模型，动态检测了伤前及烧伤后血清心肌肌球蛋白轻链Ｉ（ＣＭＬＣ１）含量及心肌酶谱（ＣＫ，ＡＳＴ和ＬＤＨ）变化，以进行烧伤后民肌损伤的评价。结果表明ＣＭＬＣ１在烧伤后１小时即明显增高，伤后１２小时比对照升高约２０倍，至伤后２４，４８仍保持高水平，伤后７２小时开始轻度下降。心肌酸疼     

烧伤大鼠早期血浆、皮肤创面及脏器TNFα的变化

采用３５％Ⅲ度烫伤大鼠模型，对烧伤大鼠早期（７２小时内）８个时相点的血浆、皮肤创面及５种脏器的ＴＮＦα含量进行了综合性分析与比较，旨在探讨烧伤早期机体上述部位ＴＮＦα变化规律及其影响。结果表明：血浆ＴＮＦα水平伤后均较伤前有显著升高，１２小时到达峰值（Ｐ＜０．０１），８、７２小时两个时相点升高有显著意义（Ｐ＜０．０５）。皮肤创面ＴＮＦα水平自伤后１至１２小时（四个时相点）均出现非常显著升高（Ｐ＜０．０１）。５种脏器的含量，伤后１、３小时无变化（Ｐ＞０．０５），自８至２４小时分别出现异常增高，并达到峰值（Ｐ＜０．０１）。提示：①严重烧伤后大鼠出现血浆、皮肤创面及五种脏器ＴＮＦα含量的异常增高，其出现峰值与当今烧伤病理生理变化高峰期相一致（伤后２４小时内）；②皮肤创面无论伤前或伤后不同时间的均值显著高于血浆及五种脏器的２．７５～８６．７倍，它的异常增高可能是造成烧伤后机体ＴＮＦα异常的主要来源     

电子顺磁共振技术检测烧伤大鼠早期血浆NO变化的研究

为探讨烧伤早期（７２小时内）血浆ＮＯ含量变化，采用雄性Ｗｉｓｔａｒ大鼠ＴＢＳＡ３５％烫伤模型，分为正常组（Ａ组）、ＬＰＳ组（脂多糖注射组，Ｌ组）、单纯烧伤组（Ｂ组）、脂多糖＋烧伤组（ＬＢ组）。分别于伤后１，３，８，１２，２４，４８，７２小时应用Ｈｂ－ＮＯ自旋捕集技术，在７７Ｋ低温测试了血浆ＮＯ浓度的变化规律，及其所产生的ＮＯ量与波谱三重峰信号强度的关系。结果表明：①Ｂ组大鼠伤后不同的时间内血浆ＮＯ与伤前值比较有降低趋势，但除伤后１２小时组与伤前比较有显著意义（Ｐ＜０．０５）外，其它各组均无显著差异（Ｐ＞０．０５）。②ＬＰＳ组血浆ＮＯ的产生，与Ａ组比较有显著差异（Ｐ＜０．０５）。ＬＢ组与伤后同时间Ｂ组比较有显著或非常显著意义（Ｐ＜０．０５或０．０１）。提示大鼠早期烧伤后经ＬＰＳ攻击后可产生过量的ＮＯ，这对于研究烧伤感染、内毒素血症有着重要的现实意义。     

烫伤大鼠肠道P物质含量和P物质能神经的观察分析

以３０％ＴＢＳＡⅢ度烫伤大鼠为模型，采用ＲＩＡ和ＩＨＣ的方法，动态观察了伤后７２小时大鼠空肠免疫活性Ｐ物质的含量及绒毛内Ｐ物质－免疫反应阳性神经纤维的变化。结果发现：（１）烫伤大鼠空肠内ｉＳＰ伤后１小时出现显著升高，４小时仍处于高水平状态；８小时后明显下降，伤后７２小时一直处于低水平状态。（２）绒毛内ＳＰ－ＩＲ阳性神经纤维在形态，分布密度和纤维内ＳＰ－ＩＲ物质的含量都有明显的改变。     

体外循环心脏手术期间降钙素基因相关肽的变化

为探讨体外循环（ＣＰＢ）心脏手术病人降钙素基因相关肽（ＣＧＲＰ）的变化和临床意义，对１５例先天性心脏病和１１例风湿性心脏病（男１９例，女７例；年龄６～５６岁；体重１３～６８ｋｇ）行ＣＰＢ心脏手术的病人，采血用放免法测定ＣＧＲＰ含量。结果麻醉后转流前、阻断主动脉２０、４０分钟、开放主动脉即刻、开放后２０、４０分钟、术后６小时和术后１０天共８个时点ＣＧＲＰ含量分别为２．３９２±１．３７５、７．４８２±６．７９３、４．６６６±２．７１２、６．５４０±４．５００、７．８２６±７．２６９、９．２８９±４．９７６、５．２４２±４．０１４、３．９８３±２．８８７ｐｍｏｌ／Ｌ。与转流前比较，ＣＧＲＰ含量在阻断主动脉至开放主动脉明显升高，开放主动脉４０分钟达高峰（Ｐ＜０．００１），术后６小时稍有回落，但仍高于转流前（Ｐ＜０．００５），术后１０天虽显著回落，但仍显著高于转流前水平（Ｐ＜０．０５）。结论：ＣＰＢ期间ＣＧＲＰ升高对心肌有重要保护作用     

不同烧伤面积血清,尿,水泡液中Zn,Cu,Fe,Ca,Mg的动态…

对探讨烧伤病人伤后血清，尿和水泡液中Ｚｎ，Ｃｕ，Ｆｅ，Ｃａ，Ｍｇ的含量，观察了１０６例烧伤病人（Ｌ组烧伤≥３０％，ＴＢＳＡ，５７例，Ｓ组烧伤〈３０％ＴＢＳＡ，４９例）伤后１，２，３，７，１４，２１，２８天血清，尿和水泡液中Ｚｎ，Ｃｕ，Ｆｅ，Ｃａ，Ｍｇ的动态变化，发现除血清Ｆｅ第１天高于正常值外，其它各元素都减低，Ｌ组比Ｓ组减低明显，尿Ｚｎ，Ｃｕ，Ｆｅ排出明显增多，尿Ｃａ，Ｍｇ排出减少，水泡液Ｚｎ，     

前列腺癌患者血清及尿液唾液酸测定的意义

为观察前列腺癌患者血唾液酸（ＳＡ）与病情、疗效及血清ＰＳＡ的关系，按血ＰＳＡ高低将病人分为３组：Ａ组（治疗前，１７例）血ＰＳＡ≥５０μｇ／Ｌ，７０７％为临床Ｃ、Ｄ１、Ｄ２期，病情进展，前列腺症状或骨痛明显。Ｂ组（治疗前，６例）血ＰＳＡ８～３７μｇ／Ｌ，临床分期为Ｃ、Ｄ期，占５０％。Ｃ组（治疗后，８例）血ＰＳＡ＜４μｇ／Ｌ，除临床Ｃ期１例，余均为临床Ｂ期术后，病愈或明显好转。血ＳＡ均值，Ａ组为３０８ｍｍｏｌ／Ｌ，大于Ｂ组２８１ｍｍｏｌ／Ｌ及Ｃ组２１４ｍｍｏｌ／Ｌ；Ａ、Ｃ间有非常显著性差异（Ｐ＜０００１），尿ＳＡ结果同血ＳＡ，Ｐ＜００５。此外，血ＰＳＡ与血ＳＡ（或尿ＳＡ）密切相关，Ｐ＜００１。同为阳性（或阴性）一致率血ＳＡＰＳＡ为８１６％，尿ＳＡＰＳＡ为７２２％。本实验所用“一步法”简便快速，血ＳＡ敏感性１０００％，特异性７８１％，不需进口试剂或设备，有助于前列腺癌的检出与病情疗效追踪观察。     

严重烧伤大鼠早期外周血中怀粒细胞CD11b／CD18分子的动态…

为探讨烧伤后早期外周血中性粒细胞（ＰＭＮ）膜上ＣＤ１１ｂ／ＣＤ１８分子的动态变化，采用大鼠３０％ＴＢＳＡⅢ烧伤模型，伤后随机分为立即复苏组和延迟复苏组，于伤前及伤后１２小时内的不同时间取血作流式细胞仪分析。结果表明，两组大鼠于伤后３０分钟起ＰＭＮ ＣＤ１１ｂ／ＣＤ１８表达就明显增加，立即复苏组于伤后４小时达到峰值；延迟复苏组在伤后１小时和８小时各有一个峰值，并比立即复苏组增高。认为烧伤后粘附分子Ｃ     

Comparison of the efficacy of serum amyloid A, C-reactive protein, and procalcitonin in the diagnosis and follow-up of necrotizing enterocolitis in premature infants

Purpose

The aim of this study was to compare the efficacy of serum amyloid A (SAA) with that of C-reactive protein (CRP), and procalcitonin (PCT) in diagnosis and follow-up of necrotizing enterocolitis (NEC) in preterm infants.

Methods

A total of 152 infants were enrolled into this observational study. The infants were classified into 3 groups: group 1 (58 infants with NEC and sepsis), group 2 (54 infants with only sepsis), and group 3 (40 infants with neither sepsis nor NEC, or control group). The data including whole blood count, CRP, PCT, SAA, and cultures that were obtained at diagnosis (0 hour), at 24 and 48 hours, and at 7 and 10 days were evaluated.

Results

A total of 58 infants had a diagnosis of NEC. Mean CRP (7.4 ± 5.2 mg/dL) and SAA (46.2 ± 41.3 mg/dL) values of infants in group 1 at 0 hour were significantly higher than those in groups 2 and 3. Although the area under the curve of CRP was higher at 0 hour in infants with NEC, there were no significant differences between groups with respect to the areas under the curve of SAA, CRP, and PCT at all measurement times. Levels of SAA decreased earlier than CRP and PCT in the follow-up of NEC (mean SAA levels were 45.8 ± 45.2, 21.9 ± 16.6, 10.1 ± 8.3, and 7.9 ± 5.1 mg/dL at evaluation times, respectively). Levels of CRP and SAA of infants with NEC stages II and III were significantly higher than those with only sepsis and/or NEC stage I.

Conclusions

Serum amyloid A, CRP, and PCT all are accurate and reliable markers in diagnosis of NEC, in addition to clinical and radiographic findings. Higher CRP and SAA levels might indicate advanced stage of NEC. Serial measurements of SAA, CRP, and PCT, either alone or in combination, can be used safely in the diagnosis and follow-up of NEC.     

前降钙素在脓毒血症早期诊断中的价值

目的　比较脓毒血症大鼠不同时间血浆中前降钙素 (PCT)和C反应蛋白 (CRP)的变化 ,探讨血浆PCT作为细菌感染早期诊断指标的敏感度和可靠性。方法　采用盲肠末端结扎穿孔的方法制备脓毒血症模型。雄性SD大鼠 30只 ,随机分为脓毒血症组 (PS)、假手术组 (SO)和正常对照组 (NC) ,每组 1 0只。分别于模型制备后 0、1 2、2 4、4 8h和对应时点经股静脉抽血 ,测定PCT和CRP。结果　PS组 1 2、2 4和 4 8h的PCT显著高于NC组和SO组的对应时点 (P <0 0 1 ) ,PS组各时点的PCT也有显著差别 (P <0 0 1 )。各组 0、1 2、2 4h的CRP无差别 ,PS组 4 8h的CRP显著高于NC和SO组 (P <0 0 1 )。结论　PCT在大鼠脓毒血症时 ,升高较早 ,且随炎症的加重而升高。PCT在诊断早期细菌感染和评估感染程度方面优于CRP。     

The study of inhibiting systematic inflammatory response syndrome by applying xenogenic (porcine) acellular dermal matrix on second-degree burns

OBJECTIVE: To investigate the influence of xenogenic (porcine) acellular dermal matrix on the systematic inflammatory reaction syndrome (SIRS), and the reaction of burn patients to tissue damage upon application to second-degree burn wounds. METHOD: Seventy-two cases of patients with acute second-degree burns were enrolled in the study. According to the total burn surface area (TBSA) and the treatment methods, we randomly divided the patients into four groups. Group A (treatment group): patients with less than 30% TBSA covered with xenogenic acellular dermal matrix. Group B (control group): patients with less than 30% TBSA covered with betadine ointment gauzes. Group C (treatment group): patients with more than 30% TBSA covered with porcine acellular dermal matrix. Group D (control group): patients with more than 30% TBSA covered with betadine ointment gauzes. Serum level of C-reactive protein (CRP) was measured by single radial immunodiffusion method on 1, 4, 7 and 14 days postburn. RESULTS: The serum level of CRP in group A was significantly less than that of in group B (P<0.05) on days 4, 7 and 14. The serum level of CRP in group C increased slowly, descended quickly and was significantly less than that of in group D on days 4, 7 and 14. CONCLUSION: The application of xenogenic (porcine) acellular dermal matrix on second-degree burn wound can decrease serum level of CRP of the patients, which may play an important role in reducing SIRS and sepsis incidence.     

Changes in 4 bearer-proteins and C3 in patients following burn injury

Four bearer-proteins including prealbumin (Pal), ceruloplasmin (CP), transferrin (Tf) and haptoglobin (HP) and C3 were determined in patients following burn injury. The patients were divided into 4 groups according to the TBSA, i.e. group 1 (1-10%), group 2 (11-30%), group 3 (31-60%) and group 4 (61-98%). Early after burn injury Pal, CP, Tf and C3 decreased markedly but C3 and CP were followed by a elevation slightly higher than normal control in group 1 and 2 but not in group 3 and 4, while Tf and Pal kept in lower level till 4 weeks after burn injury. Only elevated HP after burn injury was noticed and then decreased in group 1 and 2.     

Variations in insulin requirements can be an early indicator of sepsis in burn patients

IntroductionA >25% increase in daily insulin dosing is suggestive of possible sepsis in burn patients, however, no conclusive evidence is available regarding the time point at which insulin dosing begins to increase. The purpose of this study is to determine the exact time point at which the insulin requirement increases among non-diabetic burn patients with sepsis.MethodsA retrospective chart review in non-diabetic burn patients with ≥20% total body surface area burned (TBSA) during 2010–2018 who received a blood culture for suspected sepsis. Absolute insulin dosing at intervals (0, 24, 48, 72, and 96 h prior to blood culture) were Box–Cox transformed and compared vs.?96 h reference using mixed-effects models accounting for within-patient dependencies.ResultsFifty-eight patients (84% males, age 44 ± 17 years, TBSA% 49 ± 17.5) were included. When cube root of daily insulin dosing was regressed on each time point in a mixed-effects model, statistically significant increase in insulin dosing compared to baseline was observed for ?48 (p = 0.018), ?24 (p = 0.011), and 0 h (p = 0.008).ConclusionDaily insulin dosing increases 48 h prior to development of other clinical signs of sepsis and can be used as a sensitive early marker.     

Serum phosphate level in burn patients

Introduction

Despite plasma phosphate imbalance being rare, it is a relatively common finding in certain subsets of burn patients. It may occur due to the burn itself or as a result of the treatment. Severe hypophosphataemia (<1.0 mg dl⁻¹) is associated with a significant morbidity and a fourfold increase in mortality. In this study, the relation between serum phosphate level and the total body surface area (TBSA) of the burn was compared.

Methods

According to the percentage of TBSA of the burn, the patients (n = 155) were divided into three groups: group A with 20–29% TBSA burns, group B with 30–39% and group C with more than 40% TBSA burns (62, 48 and 45 patients, respectively).Analysis of variance (ANOVA)-repeated measure was used to detect any statistically significant difference in the three post-burn time-points of 3rd, 6th and 9th days and the mean score of the serum phosphate level between the three groups.

Results

The incidence of hypophosphataemia at 9th post-burn day in the three groups was 6.1%, 32.4% and 73.5%, respectively. There were significant differences (p < 0.05) between mean serum phosphate levels of groups A and C, B and C and A and B as well. We found significant differences between the three post-burn follow-up time stages.

Discussion

We have shown that hypophosphataemia, defined as mean serum phosphate levels below 3.0 mg dl⁻¹, was very common following burn, based on 75.6% of patients with more than 40% burn at the 3rd post-burn day. As the percentage of TBSA of burn increases, the incidence of hypophosphataemia significantly increases. We suggest that phosphate level be routinely measured after a major burn, especially in patients with a complicated course, so that appropriate replacement therapy may be started in a timely manner.     

纳米羟基磷灰石/聚酰胺的细胞相容性研究

目的对纳米晶骨修复和重建复合材料（n-HA／PA66）可能存在的潜在细胞毒性进行研究，为该材料应用于临床提供实验依据。方法参照GB／T16886.5-1997-ISO 10993-5：1992《医疗器械生物学评价细胞毒性试验体外法》的评价标准和要求，采用规定的L929细胞（小鼠结缔组织成纤维细胞），分别经直接接触、材料浸提液与细胞共培养等方式对n-HA／PA66复合材料进行细胞毒性测试，采用细胞形态观察法定性观察各组L929细胞在24、48、72h各时相点的细胞形态学变化，采用MTT比色法，测定各组1、2、4、7d L929细胞的相对增殖率来判别材料对细胞的毒性程度，并进行统计学分析比较。结果各实验组与阴性对照组两两比较对L929细胞的增殖差异均无显著性意义（P〉0．05）；各实验组与阳性对照组进行两两比较差异有显著性意义（P〈0．05）；细胞毒性为0～1级。结论n-HA／PA66与L929细胞相容性好，参照GB／T16886.5-1997-ISO 10993-5：1992标准属于安全范围。     

创面脓毒症大鼠组织ATP含量及合成酶活性的变化

目的：探讨烧伤后创面脓毒症对组织能量合成的影响。方法：60只背部30%Ⅲ度烫伤大鼠随机分为单纯烫伤组和刨面脓毒症组,创面脓毒症组大鼠创面涂以1×10~9 cfu/ml的铜绿假单胞菌观察伤后96h内心、肝、骨骼肌的ATP的含量及合成酶活性变化,同时电镜观察组织超微结构的相应改变。结果：伤后早期心肌、肝脏、骨骼肌细胞内ATP含量及合成酶活性均明显下降,此后单纯烫伤组逐渐恢复,至伤后96h脓毒症组大鼠ATP含量及合成酶活性明显低于对照组,并有与此相对应的线粒体数量和形态结构的改变。结论：烧伤后发生创面脓毒症时机体重要器官的线粒体结构损伤严重,组织ATP含量及合成酶活性明显下降,ATP合成不足加重了能量代谢的紊乱状况,线粒体的早期损伤可能是导致代谢紊乱的病理基础。     

Procalcitonin-a sepsis parameter in severe burn injuries

Procalcitonin (PCT) levels increase in patients with systemic infections; the highest levels have been found in sepsis. This study tested whether plasma procalcitonin level was related to sepsis, CRP, burn size, inhalation injury or mortality in severely burned patients over the entire clinical course.

In 27 patients with 51 (20–91)% TBSA, PCT was measured three times weekly from admission over the entire course of stay in a single ICU. Daily scoring by the “Baltimore Sepsis Scale” was performed. The patients were assigned to three groups depending on the clinical course and outcome: A=no septic complications, B=septic complications–survivors, C=septic complications–non-survivors.

PCT levels were elevated slightly at admission (mean 2.1 ng/ml) except in three patients who suffered electrical burns (mean 15.7 ng/ml). PCT peak levels correlated well with the Scoring values (r=0.84) while CRP did not (r=0.64). Peak PCT levels were significantly higher (p<0.005) in septic patients (B and C) who averaged 49.8±76.9 ng/ml, than in non-septic patients (A) who averaged peak levels of 2.3±3.7 ng/ml. The highest PCT levels were found immediately before death (86.8±97 ng/ml).

Seven patients had an inhalation injury III°. In these patients at 24 h postburn, there was no relationship between PCT levels and inhalation injury but during the later days postburn there were significant differences in PCT levels in patients with versus without inhalation injury. All patients with inhalation injury III° developed septic complications.

There was no positive correlation between the PCT-admission-levels and the TBSA, but there was a positive correlation between the TBSA and the mean peak PCT levels during the later days postburn (r=0.73; p<0.05). The cut-off value of 3 ng/ml we found reliable to indicate severe bacterial or fungal infection. PCT values over 10 ng/ml increasing over the following days were found only in life-threatening situations due to systemic infections. The individual course of PCT in one patient is more important than absolute values. PCT presented in this study as a useful diagnostic parameter in severely burned patients.     

腹腔镜与开腹阑尾切除术对小儿体液免疫和蛋白质代谢影响的比较

目的比较腹腔镜阑尾切除术（laparoscopic appendectomy,LA）和开腹阑尾切除术（open appendectomy,OA）术后体液免疫与蛋白质代谢指标水平的变化,评价LA在小儿阑尾疾病中的应用价值。方法阑尾炎患儿56例,依患儿家长意愿分为LA组和OA组,分别于术前、术后24h和72h采取外周静脉血检测免疫球蛋白IgG、IgM、IgA,补体C3、C4,C-反应蛋白（C-reactive protein,CRP）,血清前白蛋白（prealbumin,PA）和转铁蛋白（transferrin,TRF）,进行统计学处理,并比较2组患儿术后胃肠功能恢复时间、住院时间。结果2组术后24、27h免疫球蛋白IgM、IgA比较均无显著性差异（P〉0.05）。IgG在LA术后24h明显降低（P〈0.05）,术后72h与术前无差异（P〉0.05）;与OA组间比较,术后24、72h均有显著性差异（P〈0.05,P〈0.05）,但2组的变化均在正常生理范围内。补体C3在LA和OA术后24、72h组间比较无显著性差异（P〉0.05）。C4在LA术后24h较术前明显降低（P〈0.05）,但与OA组间比较无显著性差异（P〉0.05）。CRP水平在LA术后24、72h持续明显降低（P〈0.05,P〈0.05）,在OA术后则先有升高再降低（P〈0.05,P〈0.05）,组间比较术后24h有显著性差异（P〈0.05）,72h差异消失（P〉0.05）。PA在OA术后24h有明显降低（P〈0.05）,与LA组间比较有显著性差异（P〈0.05）。TRF在LA和OA术后24h均有降低（P〈0.05）,术后72h恢复接近术前水平（P〉0.05）,2组比较无显著性差异（P〉0.05）。与OA组比较,LA组胃肠功能恢复时间、住院时间明显缩短（P=0.000,P=0.000）。结论LA较OA对小儿机体体液免疫和蛋白质代谢影响小,LA更具有切口微小、胃肠功能恢复快、住院时间短的临床优点。