酪蛋白对高碘小鼠甲状腺细胞凋亡的影响

目的观察酪蛋白（CA）对高碘小鼠甲状腺细胞凋亡的影响。方法将昆明种小鼠随机分为4组：对照（NI）组、高碘（HI）组、高碘＋CA1（HI＋CA1）组、高碘＋CA2（HI＋CA2）组，喂养12个月，ELISA法检测血清白细胞介素1β（IL—1β），RT-PCR法检测甲状腺组织Fas、FasLmRNA表达水平，TUNEL法检测甲状腺细胞凋亡。结果与NI组比较，HI组小鼠血清IL-1β水平和甲状腺组织FasmRNA表达均明显增高（P〈0．05或〈0．01），且甲状腺滤泡上皮凋亡细胞数也明显增多（P〈0．01），而高碘小鼠随着CA摄入量增高，上述改变程度明显降低。结论高碘可通过提高机体IL-1β水平，诱发凋亡调控基因Fas／FasL系统表达改变，促进大鼠甲状腺细胞凋亡。而CA摄入可以部分拮抗高碘引起的上述改变，对滤泡上皮细胞具有一定的保护作用。     

高碘对大鼠海马神经细胞凋亡的影响

目的观察长期高碘对大鼠海马神经细胞形态结构及细胞凋亡的影响，并探讨其作用机制。方法SD大鼠随机分为3组：对照组、高碘Ⅰ组、高碘Ⅱ组，分别以含碘量为5、5000、10000μg／L的自来水及普通饲料喂养。6个月时检测血清总甲状腺激素（TT3、TT4）水平；光、电镜下观察神经细胞尼氏小体及超微结构改变；流式细胞仪检测细胞凋亡率及细胞周期的变化；分光光度法检测一氧化氮（NO）水平及一氧化氮合酶（NOS）活性；RT-PCR法检测凋亡相关基因bcl-2、baxmRNA表达。结果对照组、高碘Ⅰ组、高碘Ⅱ组血清TT3、TT4水平呈逐渐下降趋势，组间比较差异无统计学意义。高碘Ⅰ、Ⅱ组光镜下神经元尼氏小体模糊减少，胞质淡染，电镜下细胞核内染色质浓缩成块．聚集在核膜边缘，形成花瓣状、马蹄状等不规则形态，核膜内陷、包裹聚集的染色质形成凋亡小体。海马神经细胞凋亡率高碘Ⅰ、Ⅱ组均较对照组明显升高（P〈0．01），但高碘Ⅰ组、高碘Ⅱ组间比较未见明显差异（P〉0．05）。与对照组相比，高碘I、Ⅱ组S期细胞减少（P〈0．01），G2／M期增加（P〈0．05），G．期无明显变化（P〉0．05）。高碘Ⅰ、Ⅱ组大鼠海马组织NOS活性及NO水平均明显低于对照组（P〈0．01），bcl-2mRNA表达降低（P〈0．01）、baxmRNA表达升高（P〈0、01），但高碘I组、高碘Ⅱ组间未见明显改变（P〉0．05）。结论长期高碘可诱导大鼠海马神经细胞凋亡，细胞周期改变；其机制可能与NOS活性、NO水平降低以及bax过度表达、bcl-2表达下调有关。     

IGFBPrP1 siRNA诱导的大鼠肝星状细胞凋亡及其机制

目的研究IGFBPrP1 siRNA对大鼠肝星状细胞凋亡的影响,并探讨其可能的机制。方法体外培养大鼠肝星状细胞株（HSC-T6）,分别设立：正常对照组,阴性对照组,IGFBPrP1 siRNA转染组。IGFBPrP1 siRNA转染大鼠肝星状细胞,转染不同时间后,用CCK-8试剂盒检测肝星状细胞增殖的变化,AnnexinV/PI双标法流式细胞术检测肝星状细胞凋亡的变化,免疫细胞化学染色法检测P53及Bcl-2蛋白表达的变化。结果 （1）IGFBPrP1 siRNA转染大鼠肝星状细胞不同时间（24、48、72 h）后,转染组细胞增殖受到抑制且凋亡率明显增高,与正常对照组及阴性对照组相比,差异均有统计学意义（P〈0.01）;（2）IGFBPrP1 siRNA转染大鼠肝星状细胞48 h后,与正常对照组及阴性对照组相比,转染组P53蛋白的表达量显著增高（P〈0.01）;Bcl-2蛋白的表达明显降低（P〈0.01）。结论 IGFBPrP1 siRNA能显著抑制大鼠肝星状细胞增殖且能促进其凋亡;上调P53的表达,下调Bcl-2的表达可能是IGFBPrP1 siRNA诱导大鼠肝星状细胞凋亡的途径之一;推测抑制IGFBPrP1的表达有可能成为治疗肝纤维化的新靶点。     

老年慢性心力衰竭病人甲状腺激素水平的变化及意义

目的探讨老年慢性心力衰竭（CHF）病人甲状腺激素水平的变化及临床意义。方法采用时间分辨荧光免疫分析法，测定68例老年CHF病人抗心力衰竭治疗前后的血浆游离三碘甲状腺原氨酸（FT3）、游离甲状腺激素（FT4）、总三碘甲状腺原氨酸（TT3）、总甲状腺素（TT4）、促甲状腺表（TSH）水平，并与30名健康者对照分析。结果老年CHF组TT3、FT3较对照组下降（P＜0.05或P〈0.01），且CHF组随着心力衰竭的加重，TT3、FT3水平逐渐减低；TT4、FT4、TSH CHF各组与对照组比较无统计学意义（P〉0．05）；抗心为衰竭治疗后TT3、FT3水平明显上升（P〈0．05或P〈0.01）。结论老年CHF病人常伴有正常甲状腺痛态综合征。甲状腺激素水平的变化，可评估老年CHF病人的严重程度、治疗效果及预后。     

肾上腺功能低下与自身免疫性甲状腺炎易感性的实验研究

目的研究肾上腺功能低下与自身免疫性甲状腺疾病(AITD)易感性的关系及外环境因素中的碘对易感和非易感个体诱发AITD的影响,并探讨其发病机理.方法选用Wistar大鼠,雌性,8周龄.大鼠随机分为6组①切除大鼠1+2/3侧肾上腺(ADX),模拟肾上腺功能低下或不全,高碘(HI)饮食喂养,诱发实验性自身免疫性甲状腺炎(experiment autoimmune thyroiditis,EAT),为去肾上腺高碘饮食EAT诱发组(ADX-HI-EAT组);②去肾上腺(ADX),适碘(NI)饮食喂养,诱发EAT为ADX-NI-EAT组;③适碘(NI)饮食喂养,诱发EAT为NI EAT组;④去肾上腺(ADX),高碘饮食对照组(ADX-HI组);⑤去肾上腺(ADX)适碘饮食对照组(ADX-NI组);⑥适碘饮食正常对照组(NI组).适碘饮食是用低碘饲料(碘含量≤35 μg/kg)加适碘水(含KI为0.3mg/L)喂养,高碘饮食用低碘饲料加高碘水(含KI为0.3mg/L)喂养,高碘饮食用低碘饲料加高碘水(含KI为30g/L)喂养.EAT的诱发采用同种属不同品系的SD大鼠Tg加完全福氏佐剂(freunds complete adjuvant)免疫Wistar大鼠(Tg每次2mg,每2周1次,共3次)诱发实验性甲状腺炎(EAT)的形成,末次免疫的4周后,处死全部大鼠.各组均观察其大鼠的发病率和甲状腺组织炎症反应,检测Tg自身抗体和Th1/Th2型主要细胞因子干扰素γ和白细胞介素-4(IFN-γ和IL-4)mRNA表达水平,同时还检测免疫应答协同刺激分子CD86mRNA的表达.结果 EAT非易感的Wistar大鼠切除大部分肾上腺后,促腺上腺皮质激素(ACTH)刺激实验证实肾上腺皮质储备功能较正常对照组明显低下(P＜0.01).切除肾上腺高碘饮食诱发EAT(ADX-HI-EAT)组的甲状腺组织炎细胞浸润明显和炎症反应较重,14例中2例为甲状腺组织炎细胞浸润为"+++",3例为"++",5例为"+",无炎细胞浸润者为4例.次之是去肾上腺适碘饮食诱发自身免疫性实验性甲状腺炎组(ADX-NI-EAT),10例中1例为"+++",2例为"++",2例为"+",无炎细胞浸润者为5例.适碘饮食诱发EAT(NI-EAT)组,8例中7例无炎细胞浸润,仅1例为"±".切除肾上腺高碘饮食对照组(ADX-HI)、切除肾上腺适碘饮食对照组(ADX-NI)和正常对照组(NI)大鼠甲状腺,均未发现明显的炎细胞浸润.大鼠切除肾上腺给予高碘饮食其EAT的发病率和甲状腺炎症反应较未切除肾上腺适碘组明显增加.ADX-HI-EAT和ADX-NI EAT组大鼠甲状腺组织中IFN-γmRNA表达水平分别为0.85±0.057和0.78±0.067(细胞因子/β-actin)明显高于NI-EAT、ADX HI、ADX-NI和NI组(P＜0.01).结论肾上腺功能低下或不全是构成EAT易感性的重要因素,高碘饮食会明显地增加易感大鼠(肾上腺切除)的发病率和甲状腺炎症反应.体内CD4+Th细胞向Th1细胞偏移,Th1/Th2型细胞群的失衡在EAT的发病机理中具有重要作用.     

泌乳素对诱发自身免疫性甲状腺炎影响的实验研究

目的临床上可观察到有时自身免疫性甲状腺炎常伴有高泌乳素血症,产后甲状腺炎也有较高的发病率(5%～10%).本实验研究泌乳素在诱发实验性自身免疫性甲状腺炎(experiment autoimmune thyroiditis,EAT)形成中的影响,进一步探讨泌乳素在自身免疫性甲状腺炎发病中的作用机理.方法选用SD大鼠,雌性,10周龄.大鼠随机分为4组,即SD大鼠在实验的全过程用溴隐亭(Br)灌胃(每只大鼠溴隐亭灌胃量为1mg·kg-1·d-1),诱发EAT,高碘(HI)饮食喂养为Br-HI-EAT组;SD大鼠高碘饮食喂养,诱发EAT为HI-EAT组;高碘饮食对照组(HI组);适碘(NI)饮食正常对照组(NI组).适碘饮食是用低碘饲料(碘含量≤3 5μg/kg)加适碘水(含KI为0.3mg/L)喂养,高碘饮食用低碘饲料加高碘水(含KI为30g/L)喂养.EAT的诱发采用同种属不同品系的Wistar大鼠甲状腺球蛋白(Tg)加完全福氏佐剂(completefreunds adijuvant)免疫SD大鼠(Tg每次1mg,每2周1次,共进行3次)诱发EAT的形成,末次免疫的4周后,处死全部大鼠.各组均观察其大鼠甲状腺组织的病理改变和血清中Tg自身抗体、泌乳素水平及脾脏中的白细胞介素-2/白细胞介素-2受体(IL2/IL-2R)mRNA的表达.结果大鼠经溴隐亭干预后,诱发EAT的高碘饮食(Br-HI-EAT)组,其血清中泌乳素水平为(2.32±0.096)μg/L低于诱发EAT的高碘饮食(HI-EAT)组(3.56±0.048)μg/L,P＜0.05.Br-HI-EAT组的发病率和甲状腺组织的炎细胞浸润(8例中有2例为"++",3例为"+",5例为"-")明显的轻于HI-EAT组(7例中2例为"+++",1例为"++",4例为"+");未诱发EAT的高碘饮食正常对照组(HI组)和正常对照组(NI组)的甲状腺组织中,未发现明显的炎细胞浸润;BR-HI-EAT组大鼠脾脏IL-2和IL-2RmRNA的表达分别为0.27±0.027和0.48±0.039(细胞因子/β-actin)也较HI-EAT组(0.60±0.013和0.75±0.018)明显降低(P＜0.01);诱发EAT两组大鼠血清中Tg自身抗体平均水平明显高于未诱发EAT大鼠(P＜0.01).结论大鼠经溴隐亭于预,致血清中泌乳素水平下降,其IL-2/IL-2RmRNA的表达也随之减少,降低IL-2/IL-2R系统对免疫应答的激活作用,其EAT的发病率和甲状腺组织中炎症反应得到缓解,可以认为泌乳素水平的变化也是影响自身免疫性疾病发病机制中的重要因素.     

TRAIL体外诱导人肝星形细胞LX-2凋亡作用及调控机制

目的研究肿瘤坏死因子相关凋亡诱导配体（TRAIL）诱导肝星形细胞凋亡情况及调控机制。方法用RT-PCR检测LX-2中α-SMAmRNA和DR5mRNA的表达;MTT比色法、流式细胞术检测外源性TRAIL对LX-2细胞增殖和诱导细胞凋亡的影响;采用Westernblot检测Bax、Caspase3表达。结果培养的LX-2表达α-SMAmRNA和DR5mRNA逐渐增加,TRAIL可以抑制其细胞增殖,与剂量相关（P〈0.05）。与对照组比较,TRAIL诱导活化的LX-2细胞凋亡明显增加（P〈0.05）,Western blot分析显示TRAIL作用下,LX-2线粒体Bax、细胞质Caspase3表达上调。结论外源性TRAIL可以诱导活化的LX-2凋亡,其机制与DR5及线粒体Bax表达上调有关。     

不同碘营养状态对大鼠肝组织Ⅰ型5′脱碘酶的影响

目的研究不同碘营养状态对大鼠肝组织甲腺氨酸Ⅰ型5′脱碘酶（DI）表达水平及活性的影响。方法正常1月龄Wistar大鼠根据碘摄入量不同分为6组，饲养3个月后处死。放免法测定血清甲状腺激素水平。提取肝组织总RNA，以β—actin为内对照，半定量RT-PCR分析DI基因的表达水平。Chopra氏方法测定肝组织匀浆液中DI的脱碘活性。结果LI组TT4和FT4显著低于其他5组（P〈0．05），100HI组TT3和FT3显著低于其他5组（P〈0．05），100HI组TT4和FT4显著低于NI、5HI、10HI和50HI组（P〈0．05）。大鼠肝组织DI基因mRNA表达量6组间差异有统计学意义（P〈0．01），LI组显著高于其他5组（P〈0．05），不同剂量HI组和NI组相比差异均无统计学意义（P〉0．05）。大鼠肝组织DI活性6组间差异有统计学意义（P〈0．01），LI组显著高于其他5组（P〈0．05），50HI组和100HI组显著低于其他4个组（P〈0．05）。结论在碘缺乏状态下。大鼠出现以低T4为主要表现的甲状腺功能减退（甲减），DI活性和DI基因表达水平代偿性上调，使机体维持足够的T3水平，以避免周围组织出现器官性甲减。高碘仅在转录后水平影响DI，表现为直接抑制DI的活性。使血清TT3和FT3下降，机体出现失代偿性周围组织器官性甲减。DI对碘过量有一定的耐受能力，这种耐受性有一定的阈值。     

原发性甲状腺功能减退与肾功能的关系

目的为探讨原发性甲状腺功能减退症（原发性甲减）患者甲状腺功能与肾功能的关系。方法检测31例原发性甲减患者和20例健康对照组的空腹血清游离三碘甲状腺原氨酸（FT3）、游离四碘甲状腺原氨酸（FT4）、高灵敏促甲状腺激素（sTSH）、尿素氮（BUN）、肌酐（Cr）、尿酸（UA）、肌酐清除率（CCr）、尿蛋白定性。结果原发性甲减患者Cr、UA、尿蛋白阳性率均明显高于对照组（P值均〈0．05），而CCr低于对照组（P〈0．05），并且FT3与CCr呈正相关（r=0．5441，P〈0．05），与UA呈负相关（r=-0．4372，P〈0．05）。但BUN在甲减组和对照组无统计学差异。结论提示原发性甲减患者常伴Cr、UA、尿蛋白阳性率升高，CCr下降。其FT3水平下降与CCr、UA升高关系更密切。     

AECOPD患者甲状腺激素水平变化及临床意义

目的观察慢性阻塞性肺疾病急性加重期（AECOPD）患者甲状腺激素水平的变化,探讨其临床意义。方法采用化学发光法测定102例AECOPD患者血清总三碘甲状腺原氨酸（TT3）、总甲状腺素（TT4）、游离三碘甲状腺原氨酸（FT3）、游离甲状腺素（FT4）、促甲状腺素（TSH）水平,并与84例健康体检者进行对照。结果 AECOPD血清TT3、TT4、FT3与对照组比较差异有统计学意义（P〈0.01）;好转组与死亡组AECOPD患者血清TT3、FT3比较差异有统计学意义（P〈0.05或P〈0.01）;无呼吸衰竭组与Ⅰ型呼衰组、Ⅱ型呼衰组患者血清TT3、FT3比较差异有统计学意义（P〈0.01）。结论血清甲状腺激素水平变化反映AECOPD患者病情严重程度,可用于AECOPD患者病情的评估。     

The immunoneuroendocrine role of melatonin

Abstract: A tight, physiological link between the pineal gland and the immune system is emerging from a series of experimental studies. This link might reflect the evolutionary connection between self-recognition and reproduction. Pinealectomy or other experimental methods which inhibit melatonin synthesis and secretion induce a state of immunodepression which is counteracted by melatonin. In general, melatonin seems to have an immunoenhancing effect that is particularly apparent in immunodepressive states. The negative effect of acute stress or immunosuppressive pharmacological treatments on various immune parameters are counteracted by melatonin. It seems important to note that one of the main targets of melatonin is the thymus, i.e., the central organ of the immune system. The clinical use of melatonin as an immunotherapeutic agent seems promising in primary and secondary immunodeficiencies as well as in cancer immunotherapy. The immunoenhancing action of melatonin seems to be mediated by T-helper cell-derived opioid peptides as well as by lymphokines and, perhaps, by pituitary hormones. Melatonin-induced-immuno-opioids (MHO) and lymphokines imply the presence of specific binding sites or melatonin receptors on cells of the immune system. On the other hand, lymphokines such as -γ-interferon and interleukin-2 as well as thymic hormones can modulate the synthesis of melatonin in the pineal gland. The pineal gland might thus be viewed as the crux of a sophisticated immunoneuroendocrine network which functions as an unconscious, diffuse sensory organ.     

Changes in connexin43, the gap junction protein of astrocytes, during development of the rat pineal gland

Abstract: The abundance of gap junctions between rat pineal astrocytes formed by connexin43 (Cx43) was studied during development. Levels and distribution of Cx43 were measured by immunoblotting and indirect immunofluorescence, respectively. The amount of Cx43 in cells located within the gland was low until about the 7th postnatal day and increased to adult values between the 14th and 21st days postpartum. Although astrocytes, recognized by their vimentin immunoreactivity, were scarce before birth, they were abundant by the 7th postnatal day suggesting that the low levels of Cx43 found at this age corresponded to a low expression of this protein. Localization of the immunoreactivity to Cx43 and vimentin showed a close correlation, indicating that mature or immature pineal astrocytes form gap junctions made of Cx43. Since Cx43 levels attained their adult values at about the time the innervation and the functional state of the gland reached maturity (2–3 weeks after birth), it is proposed that astrocyte gap junctions are involved in the function of the adult rat pineal gland.     

Response of rat pineal melatonin to calcium, magnesium, and lithium is circadian stage dependent

Abstract: Herein we documented the response of pineal melatonin production to electrolytes known to be effective on pineal function in view of a possible circadian stage dependence. We studied the release of melatonin by perifused rat pineal glands at 2 different circadian stages corresponding to the middle of the light and dark periods, i.e., respectively, 7 and 19 HALO (Hours After Light Onset, L:D = 12:12). The initial efflux rates were, as expected, much higher in the perifusates of glands removed from rats sacrificed during the dark phase than of those removed during the light phase. After 3 hr of perifusion, melatonin release reached similar levels which were found constant up to the 8th hr of perifusion, whatever the circadian stage. Perifusion of the glands with physiological concentrations for the rat of calcium (5.2 mmol/1) and magnesium (1.34 mmol/1) resulted in a stimulatory effect on the pineal glands removed from rats sacrificed in the middle of the dark period (19 HALO), whereas no effects were observed on the pineal glands removed from rats sacrificed during the light (7 HALO). Lithium (0.28 and 0.55 mmol/1) was ineffective on melatonin release in pineal glands removed 7 and 19 HALO. Our results show differences in the initial efflux rates of melatonin and in the response of perifused pineal glands to calcium and magnesium according to the circadian stage.     

Conservative management of perforated duodenal diverticulum： A case report and review of the literature

Duodenal diverticula are a relatively common condition. They are asymptomatic, unless they become complicated, with perforation being the rarest but most severe complication. Surgical treatment is the most frequently performed approach. We report the case of a patient with a perforated duodenal diverticulum, which was diagnosed early and treated conservatively with antibiotics and percutaneous drainage of secondary retroperitoneal abscesses. We suggest this method could be an acceptable option for the management of similar cases, provided that the patient is in good general condition and without septic signs.     

Presence of immunoreactive growth hormone and prolactin in the ovine pineal gland

Abstract: The use of antisera raised against bovine growth hormone (GH) and ovine prolactin (PRL) enabled the detection of related immunoreactive (ir) sequences of proteins in ovine pineal tissue. The isolation of PRL-like ir-material was accomplished using a 0.25 M ammonium sulphate (pH 5.5) extraction followed by ethanol precipitation, whereas the resulting 2.0 M ammonium sulphate (pH 7.0) precipitate contained a GH-like immunoreactivity. Gel chromatography of the GH-like immunoreactivity (Sephadex G-100) indicated the presence of several GH-like fragments ranging in the M_r range of 7,000 to 55,000. Analyses of the PRL-like ir-material found in pineal tissue on HPLC using a TSK 545-DEAE column led to the resolution into a single peak of immunoreactivity. A single peak of activity was also observed following chromatofocusing and hydrophobic interaction chromatography of the ir-peak from the TSK 545-DEAE column. The PRL-like ir-material inhibited the binding of [¹²⁵I]ovine PRL-S14 to anti-ovine PRL antibodies without showing an affinity for binding to anti-rat PRL or anti-bovine GH antibodies. Scatchard analysis of the binding of pineal PRL-like ir-material and pituitary ovine PRL-S14 to liver membranes from day-20 pregnant rats revealed similar affinity constants (K_a of 4.7 ± 0.2 × 10⁹ M^-1). In addition, the replication of Nb 2 Node rat lymphoma cells was stimulated by pineal PRL-like ir-material, an effect known to be specific for lactogenic hormones. The pineal PRL-like immunoreactivity appeared on sodium dodecyl sulfate polyacrylamide gels as a single major band of M_r 24,000. The functional status of PRL-and GH-like ir-material in the ovine pineal remains to be determined, but evidence is presented that the overall protein synthesis rate of the rat pineal responded to circulating concentrations of PRL.     

Microbiology of human immunodeficiency virus anorectal disease

PURPOSE: Individuals who are seropositive for the human immunodeficiency virus are at high risk for opportunistic infection and anorectal disorders. Little prospective information is available regarding anorectal pathogens in these patients. METHODS: One hundred sixty-three HIV-seropositive patients presented to the colorectal clinic between 1989 and 1992. Forty-seven (29 percent) patients were thought to have an infectious process and were prospectively studied using a standardized multiculture protocol. RESULTS: Mean age was 33 (range, 19–59) years. All were male; high-risk behavior accounted for 87 percent of HIV transmissions. Presenting complaints included anorectal pain (79 percent), pus per anum (28 percent), and blood per anum (26 percent). Examination revealed perianal tenderness (60 percent), condyloma (38 percent), perianal ulcers (38 percent), and anal fissures (34 percent). Sixty-six sets of cultures were performed; 28 patients had one set, 15 had two sets, and 4 had three sets. Thirty-two of these 47 patients (68 percent) had positive cultures including herpes (50 percent), cytomegalovirus (25 percent),Neisseria gonorrhoeae (16 percent), chlamydia (16 percent), acidfast bacilli (2 percent), and others (9 percent). Six of 32 patients with positive cultures had more than one organism cultured. Sixteen (50 percent) patients with positive cultures were treated medically, 8 (25 percent) were treated surgically and 8 (25 percent) were treated with both modalities. Sixty-one procedures were performed on 17 patients for condylomata. Eighteen patients had 20 procedures for abscesses, 50 percent of whom had positive cultures for other than common bowel flora; all improved. Fourteen patients underwent 33 procedures for perianal fistulas.Mycobacterium fortuitum was cultured from one patient who required 13 procedures for abscesses and fistulas. Forty-five (96 percent) patients were followed for an average of 12.5 months ±2.9 SEM (range, 1–94 months). Symptoms were improved or resolved in 22 of 32 (69 percent) patients with positive cultures and in 11 of 13 (84 percent) with negative cultures. CONCLUSIONS: Specific pathogens may often be identified in human immunodeficiency virus-seropositive patients with anorectal disorders if aggressively sought. Although patients without specific pathogens identified may be expected to improve with planned empiric treatment, positive identification allows more directed therapy.