The effect of ultraviolet light radiation on Mycobacterium leprae

Ultraviolet (UV) light is recognized as a potent sterilizing aid, but its relative effectiveness against Mycobacterium leprae has not been shown. We examined the influence of UV on the growth and metabolic activity of M. leprae harvested fresh from foot pads of nude mice. Temporary static suspensions were exposed to timed intervals of UV radiation generated from a fixed source to constitute dosages ranging from 0-12.64 x 10(4) erg/cm2. The metabolic activity of the bacilli was indexed by the oxidation of 14C-palmitate in BACTEC 12-B vials. The long-term effects of irradiation on cell division and growth were assessed by inoculation of BALB/c mouse foot pads. The metabolic activity in BACTEC showed an immediate dose-response-related decline to a maximum of 50% of the control activity after exposure to 6.3 x 10(4) erg/cm2. Mouse foot pad studies showed a similar dose-response pattern. Effective-dose determinations based on metabolic or foot pad data were similar. UV doses of 3.52 x 10(4) erg/cm2 resulted in an average 50% killing, and 7.73 x 10(4) erg/cm2 killed 84% of the M. leprae exposed. This UV sensitivity is similar to that reported for M. tuberculosis. UV sterilization and disinfection practices suitable for M. tuberculosis are likely to be equally effective for M. leprae.     

Mechanism of growth delay induced in Escherichia coli by near ultraviolet radiation.

Continuously growing cultures of E. coli B/r were irradiated with a fluence of broad-band near-ultraviolet radiation (315-405 nm) sufficient to cause extensive growth delay and complete cessation of net RNA synthesis. Chloramphenicol treatment was found to stimulate resumption of RNA synthesis, similar to that observed with chloramphenicol treatment after amino-acid starvation. E. coli strains in which amino-acid starvation does not result in cessation of RNA synthesis ("relaxed" or rel- strains) show no cessation of growth and only a slight effect on the rate of growth or of RNA synthesis. These findings show that such near-UV fluences do not inactivate the RNA synthetic machinery but affect the regulation of RNA synthesis, in a manner similat to that produced by amino-acid starvation. Such regulation is believed to be mediated through alterations in concentration of guanosine tetraphosphate (ppGpp), and our estimations of ppGpp after near-UV irradiation are consistent with such an interpretation. These data, combined with earlier published data, strongly suggest that the mechanism of near-UV-induced growth delay in E. coli involves partial inactivation of certain tRNA species, which is interpreted by the cell in a manner similar to that of amino-acid starvation, causing a rise in ppGpp levels, a shut-off of net RNA synthesis, and the induction of a growth delay.     

Vitamin D receptor-dependent inhibition of mammary tumor growth by EB1089 and ultraviolet radiation in vivo

1,25-Dihydroxyvitamin D(3) (1,25D), the biologically active form of vitamin D(3), exerts antiproliferative and proapoptotic effects in multiple transformed cell types, and thus, the vitamin D signaling pathway represents a potential anticancer target. Although chronic treatment with 1,25D induces hypercalcemia, synthetic vitamin D analogs have been developed that inhibit tumor growth in vivo with minimal elevation of serum calcium. Furthermore, vitamin D is synthesized in skin exposed to UV light, and this route of vitamin D elevation is not associated with hypercalcemia. In this study, we examined whether enhancement of vitamin D status via exogenous (EB1089, a 1,25D analog) or endogenous (UV exposure) approaches could exert antitumor effects without hypercalcemia. We used mammary xenografts with differential vitamin D receptor (VDR) expression to examine whether the antitumor effects of either therapy are receptor mediated. We present evidence that both EB1089 and UV exposure inhibit tumor growth via induction of growth arrest and apoptosis. These antitumor effects were observed only in xenografts containing VDR-positive tumor cells; heterogeneous tumors containing VDR-negative tumor cells and VDR-positive stromal and endothelial cells were unresponsive to both therapies. No evidence for antiangiogenic effects of EB1089 were detected in this model system. Neither EB1089 nor UV was associated with overt toxicity, but keratinocyte proliferation was increased in UV-exposed skin. These data provide proof of principle that UV exposure modulates tumor growth via elevation of vitamin D signaling and that therapeutic approaches designed to target the vitamin D pathway will be effective only if tumor cells express functional VDR.     

环氧合酶-2的表达在放疗抵抗中的作用及其机制研究进展

放射治疗是肿瘤综合治疗的重要手段,在其应用日趋广泛的同时,放疗抵抗问题也日趋凸显,放疗敏感性不高成为影响肿瘤患者放疗疗效的关键问题。环氧合酶-2已被证实参与肿瘤的发生发展,近期研究证实其表达能导致放疗抵抗。该文将对环氧合酶-2的表达在放疗抵抗的产生中的作用及其机制进行综述。     

医院内气载耐甲氧西林金黄葡萄球菌（MRSA）耐药性及耐药基因分析

目的监测医院中气载耐甲氧西林金黄葡萄球菌（MRsA）对临床常用抗生素的耐药性及相关耐药基因。方法用FA-1型六级筛孔撞击式空气微生物采样器采集5所医院的大厅、ICU及病房等场所的空气,分离金黄葡萄球菌,采用头孢两丁纸片法检测MRSA,应用K-B法测定MRSA药敏情况,应用多重PCR扩增MRSA甲氧西林耐药基因rrlecA,氨基糖苷修饰酶基因aacA-aphD,大环内酯类23srRNA甲基化酶基因ermA、errnC,四环素类核糖体保护蛋白基因tetM、tetK以及金黄葡萄球菌属特异性基因16srDNA。结果共采集空气样品250份,分离气载金黄葡萄球菌219株,其中MRSA88株。所有气载MRSA均对青霉素及头孢曲松耐药,对庆大霉素、红霉素及四环素耐药率〉90％,但均对万古霉及素替考拉宁敏感。所有MRSA菌株iTIeCA基因和16srDNA基因均阳性,vat（A）、vat（B）、vat（C）基因均阴性。96％以上MRSA菌株可同时检出氨基糖苷类、红霉素类和四环素类耐药基因,呈现多重耐药;携带aacA—aphD、erm（A）或（和）erm（C）、tetM或（和）tetK耐药基因的MRSA菌株总检出率分别为96．59％、100％和96．59％。结论5所医院空气中均存在MRSA分布且呈多重耐药性,相关耐药基因检出率高。因此应加强对医院空气中致病菌的监测与消毒,预防和控制医院气源病原微生物感染的发生。     

The effects of radiation exposure on interventional cardiologists

Professional exposure of interventional cardiologist to low-dose radiation prompts cellular changes that may protect from harm.     

The effects of insulin-like growth factors on tumorigenesis and neoplastic growth

Several decades of basic and clinical research have demonstrated that there is an association between the insulin-like growth factors (IGFs) and neoplasia. We begin with a brief discussion of the function and regulation of expression of the IGFs, their receptors and the IGF-binding proteins (IGFBPs). A number of investigational interventional strategies targeting the GH or IGFs are then reviewed. Finally, we have assembled the available scientific knowledge about this relationship for each of the major tumor types. The tumors have been grouped together by organ system and for each of the major tumors, various key elements of the relationship between IGFs and tumor growth are discussed. Specifically these include the presence or absence of autocrine IGF-I and IGF-II production; presence or absence of IGF-I and IGF-II receptor expression; the expression and functions of the IGFBPs; in vitro and in vivo experiments involving therapeutic interventions; and available results from clinical trials evaluating the effect of GH/IGF axis down-regulation in various malignancies.     

2004—2008年北京大学第三医院临床分离的金黄色葡萄球菌耐药性分析

目的研究临床分离的金黄色葡萄球菌(SAU)与耐甲氧西林金黄色葡萄球菌(MRSA)的耐药性。方法收集2004—2008年12月北京大学第三医院细菌室分离的SAU,采用纸片扩散法进行药物敏感试验,对苯唑西林抑菌直径≤20mm为MRSA。结果5年共分离SAU1521株,MRSA890株,占SAU58.5%。SAU主要分布于急诊科255株(16.8%)、其他内科201株(13.2%);外科危重病房171株(SICU,11.2%)。MRSA主要分布于急诊科199株(22.4%);SICU148株(16.6%)和呼吸危重病房131株(14.7%)等。痰标本中分离的MRSA菌株最多,共725株(81.5%);其次为创伤口分泌物62株(7.0%)以及血液27株(3.0%);咽试子17株(1.9%);尿液16株(1.8%);胸腔引流液8株(0.9%);其他标本25株(2.8%)。最近3年门诊分离出MRSA菌株,主要来自痰液、尿液和伤口分泌物。MRSA对多种药物耐药,但对SMZ有较好敏感性,无耐万古霉素和替考拉宁MRSA菌株;各科室分离的MRSA对多种抗生素均高度耐药。结论近5年中我院SAU尤其是MRSA分离率有所增加。MRSA对β内酰胺类、大环内酯类和喹诺酮类抗生素的耐药率均在90%以上,但未发现耐万古霉素和替考拉宁的MRSA菌株。加强对SAU耐药性的监测,对合理应用抗生素具有重要意义。     

The effects of experimental hyperthyroidism on hemorheology and plasma fibrinogen concentration

The present study in female rats determined the effects of experimental hyperthyroidsm on hemorheological parameters and fibrinogen concentration. To induce experimental hyperthyroidism l-thyroxine (0.4 mg/100 g fodder) was added to the fodder of the experimental group rats for 20 d. After experimental duration, T₃, T₄, and TSH levels, plasma and blood viscosity, hematocrit, erythrocyte rigidity index, and plasma fibrinogen concentration values of both the control and the experimental group animals were determined and evaluated. In the experimental group, T₃ and T₄ levels were higher and TSH levels lower than that of the control rats (respectively, p<0.01, p<0.001, p<0.001). Plasma viscosity and fibrinogen concentration of hyperthyroid group were found significantly higher than controls (p<0.01). However there was no significant difference found in blood viscosity, hematocrit, and erythrocyte rigidity index between control and experimental groups. Thus, hyperthyroidism induced increased fibrinogen concentration can alter the rheological structure of blood by inducing increase in plasma viscosity.     

The effects of experimental hypothyroidism on hemorheology and plasma fibrinogen concentration

Effects of hypothyroid on hemorheology of patients had widely attracted the attention of researchers during last decade. The present study has been planned with the purpose to determine the effects of experimental hypothyroidism on hemorheological parameters and fibrinogen concentration. To induce experimental hypothyroid methimazole (75 mg/100g) was added to the fodder of an experimental group rats for 20 d. After experimental duration, plasma and blood viscosity, hematocrit (Hct), hemoglobin, erythrocyte rigidity index, and plasma fibrinogen concentration values of both the control and the experimental group animals were determined and evaluated. The serum T₃ and T₄ levels of the experimental group were found lower (p<0.001) but TSH level higher (p<0.001) than that of the control group. Plasma viscosity and fibrinogen concentration of hypothyroid group were found significantly higher than controls (p<0.01). Hematocrit and hemoglobin values were also found lower in the experimental group than the control group animals (p<0.01). However, there was no significant difference found in blood viscosity at the original Hct value but there was a significant increase at standard Hct value (p<0.01). There was also no change in erythrocyte rigidity index between control and experimental groups. According to these results it may be said that in hypothyroidism, increased fibrinogen concentration may alter the rheological structure of blood by inducing increase in plasma viscosity.     

Let the sun shine in: effects of ultraviolet radiation on invasive pneumococcal disease risk in Philadelphia, Pennsylvania

Background  

Streptococcus pneumoniae is a common cause of community acquired pneumonia and bacteremia. Excess wintertime mortality related to pneumonia has been noted for over a century, but the seasonality of invasive pneumococcal disease (IPD) has been described relatively recently and is poorly understood. Improved understanding of environmental influence on disease seasonality has taken on new urgency due to global climate change.