Human exposure at two radio frequencies (450 and 2450 MHz): Similarities and differences in physiological response

Thermoregulatory responses of heat production and heat loss were measured in two different groups of seven adult volunteers (males and females) during 45‐min dorsal exposures of the whole body to 450 or 2450 MHz continuous‐wave radio frequency (RF) fields. At each frequency, two power densities (PD) were tested at each of three ambient temperatures (T_a = 24, 28, and 31 °C) plus T_a controls (no RF). The normalized peak surface specific absorption rate (SAR), measured at the location of the subject's center back, was the same for comparable PD at both frequencies, i.e., peak surface SAR = 6.0 and 7.7 W/kg. No change in metabolic heat production occurred under any exposure conditions at either frequency. The magnitude of increase in those skin temperatures under direct irradiation was directly related to frequency, but local sweating rates on back and chest were related more to T_a and SAR. Both efficient sweating and increased local skin blood flow contributed to the regulation of the deep body (esophageal) temperature to within 0.1 °C of the baseline level. At both frequencies, normalized peak SARs in excess of ANSI/IEEE C95.1 guidelines were easily counteracted by normal thermophysiological mechanisms. The observed frequency‐related response differences agree with classical data concerning the control of heat loss mechanisms in human beings. However, more practical dosimetry than is currently available will be necessary to evaluate realistic human exposures to RF energy in the natural environment. Bioelectromagnetics 20:12–20, 1999. Published 1999 Wiley‐Liss, Inc.     

Faithful expression of green fluorescent protein (GFP) in transgenic zebrafish embryos under control of zebrafish gene promoters

Although the zebrafish has become a popular model organism for vertebrate developmental and genetic analyses, its use in transgenic studies still suffers from the scarcity of homologous gene promoters. In the present study, three different zebrafish cDNA clones were isolated and sequenced completely, and their expression patterns were characterized by whole‐mount in situ hybridization as well as by Northern blot hybridization. The first clone encodes a type II cytokeratin (CK), which is specifically expressed in skin epithelia in early embryos and prominently expressed in the adult skin tissue. The second clone is muscle specific and encodes a muscle creatine kinase (MCK). The third clone, expressed ubiquitously in all tissues, is derived from an acidic ribosomal phosphoprotein P0 (arp) gene. In order to test the fidelity of zebrafish embryos in transgenic expression, the promoters of the three genes were isolated using a rapid linker‐mediated PCR approach and subsequently ligated to a modified green fluorescent protein (gfp) reporter gene. When the three hybrid GFP constructs were introduced into zebrafish embryos by microinjection, the three promoters were activated faithfully in developing zebrafish embryos. The 2.2‐kb ck promoter was sufficient to direct GFP expression in skin epithelia, although a weak expression in muscle was also observed in a few embryos. This pattern of transgenic expression is consistent with the expression pattern of the endogenous cytokeratin gene. The 1.5‐kb mck promoter/gfp was expressed exclusively in skeletal muscles and not elsewhere. By contrast, the 0.8‐kb ubiquitous promoter plus the first intron of the arp gene were capable of expressing GFP in a variety of tissues, including the skin, muscle, lens, neurons, notochord, and circulating blood cells. Our experiments, therefore, further demonstrated that zebrafish embryos can faithfully express exogenously introduced genes under the control of zebrafish promoters. Dev. Genet. 25:158–167, 1999. © 1999 Wiley‐Liss, Inc.     

TGF-β receptor expression on human keratinocytes: A 150 kDa GPI-anchored TGF-β1 binding protein forms a heteromeric complex with type I and type II receptors

Keratinocytes play a critical role in re-epithelialization during wound healing, and alterations in keratinocyte proliferation and function are associated with the development of various skin diseases. Although it is well documented that TGF-β has profound effects on keratinocyte growth and function, there is a paucity of information on the types, isoform specificity and complex formation of TGF-β receptors on keratinocytes. Here, we report that in addition to the types I, II, and III TGF-β receptors, early passage adult and neonatal human keratinocytes display a cell surface glycosylphosphatidylinositol (GPI)-anchored 150 kDa TGF-β1 binding protein. The identities of the four proteins were confirmed on the basis of their affinity for TGF-β isoforms, immunoprecipitation with specific anti-receptor antibodies, sensitivity to phosphatidylinositol specific phospholipase C and dithiothreitol, and 2-dimensional electrophoresis. Interestingly, the antitype I TGF-β receptor antibody immunoprecipitated not only the type I receptor, but also the type II receptor and the 150 kDa component, suggesting that the 150 kDa component form heteromeric complexes with the signalling receptors. In addition, two-dimensional (nonreducing/reducing) electrophoresis confirmed the occurrence of a heterotrimeric complex consisting of the 150 kDa TGF-β1 binding protein, the type II receptor, and the type I receptor. This technique also demonstrated the occurrence of types I and II heterodimers and type I homodimers of TGF-β receptors on keratinocytes, supporting the heterotetrameric model of TGF-β signalling proposed using mutant cells and cells transfected to overexpress these receptors. The keratinocytes responded to TGF-β by markedly downregulating all four TGF-β binding proteins and by potently inhibiting DNA synthesis. The demonstration that the 150 kDa GPI-anchored TGF-β1 binding protein forms a heteromeric complex with the TGF-β signalling receptors suggests that this GPI-anchored protein may modify TGF-β signalling in human keratinocytes. J. Cell. Biochem. 70:573–586, 1998. © 1998 Wiley-Liss, Inc.     

QuantiFERON-TB Gold Plus Test in Diagnostics of Latent Tuberculosis Infection in Children Aged 1–14 in a Country with a Low Tuberculosis Incidence

The aim of the study was to evaluate the QuantiFERON-TB Gold Plus (QFT-Plus) test usability in the identification of latent tuberculosis infection (LTBI) in children and the determination of features associated with tuberculin skin test (TST) and QFT-Plus-positive results concerning LTBI. Two-hundred thirteen children aged 1–14 were screened for LTBI due to household contact with TB, suspected TB, or were qualified for biological therapy. The objective of this study was to evaluate the QFT-Plus affectivity as a diagnostic test in the absence of a gold standard (GS) test for the diagnosis of LTBI. The children were diagnosed with QFT-Plus, TST, and culture of TB. The QFT-Plus results were analyzed depending on the children’s age, TST size, and type. In children aged 1–4, the positive predictive value of QFT-Plus was 1, the negative predictive value was 0.94, QFT-Plus sensitivity was 75%, and specificity was 100%. It was observed that in children aged 5–14 years, the level of agreement decreased to the substantial, i.e., 87.2%. Moreover, the negative predictive value was 0.83. QFT-Plus sensitivity was 64%, and specificity was 100%. Statistical analysis of QFT-Plus and TST results showed substantial and almost perfect agreements. Our study suggests that QFT-Plus is helpful in a pediatric practice showing good sensitivity and specificity for LTBI. The BCG vaccine, infections, and concomitant morbidities do not affect QFT-Plus results.     

皮毛之道：以表皮器官为研究模型探讨再生生物学与再生医学的基础概念

再生医学是一个具有巨大潜力的新兴医学领域。该文以此为方向讨论了再生医学研究中的三个关键问题,并以非神经外胚层器官的干细胞行为为例做进一步的探讨。第一,如何获取干细胞,介绍了包括胚胎干细胞、组织干细胞和诱导性多能干细胞的获得途径,以及若干组织细胞重编程的成功范例;第二,如何将干细胞转化为组织和器官,这需要了解干细胞分化以及形态发生的机制,并以羽毛的形态发生为模型,引入了千细胞拓扑生物学的概念以及干细胞微环境调控塑造器官形态的机制;第三,如何将干细胞及其转化产物置于患者体内,并以鼠毛生长周期波为例,阐明了宏观环境因素如何调控干细胞的活性：最后,还分析了在器官发生中干细胞的自组织对于新生毛发组织工程的重要意义。该文的许多原则不仅限于皮肤,同时也适用于其它体内器官。通过对生物再生的过程的基础研究,我们可以受到生物再生之道的启发,逐渐理解组织修复及再生的机制,并提高分子和细胞水平上的干细胞操作技术,希望在不久的将来将干细胞研究成果应用于临床医学。     

Conductivities of pig dermis and subcutaneous fat measured with rectangular pulse electrical current

We examined experimentally the relationship between perpendicular and tangential electrical conductivities, σ, and peak current density J, in pig skin dermis and subcutaneous fat specimens by using a four-electrode measuring system with rectangular pulse electrical current (RPEC). We also investigated the relationship of the conductivity, σ, vs. pulse rate, f. The rates were selected at 8, 32, 64, and 128 pulses per second (pps), and the pulse width was fixed at 140 μs. These values are often used in vivo to enhance cutaneous regeneration with RPEC stimulation. It was found that the conductivities may be approximated to be for the skin dermis and for the subcutaneous fat in the conditions of this experiment. These findings implies that the conductivities of pig skin dermis and subcutaneous fat are anisotropic, i.e., σ_x = σ_y ≠ σ_z. It was also found that the conductivities are independent of current density and pulse rate in the current range from 20 μA/cm² to 120 mA/cm². © 1996 Wiley-Liss, Inc.     

Molecular Changes Underlying Genistein Treatment of Wound Healing: A Review

Estrogen deprivation is one of the major factors responsible for many age-related processes including poor wound healing in postmenopausal women. However, the reported side-effects of estrogen replacement therapy (ERT) have precluded broad clinical administration. Therefore, selective estrogen receptor modulators (SERMs) have been developed to overcome the detrimental side effects of ERT on breast and/or uterine tissues. The use of natural products isolated from plants (e.g., soy) may represent a promising source of biologically active compounds (e.g., genistein) as efficient alternatives to conventional treatment. Genistein as natural SERM has the unique ability to selectively act as agonist or antagonist in a tissue-specific manner, i.e., it improves skin repair and simultaneously exerts anti-cancer and chemopreventive properties. Hence, we present here a wound healing phases-based review of the most studied naturally occurring SERM.     

Importance of pre-enrichment media for isolation of Salmonella spp. from swine and poultry

The performance of two new (1-day) culture methods, Salmonella Enrichment Broth (SEB) and Revive, and an alternative pre-enrichment broth, designated Universal pre-enrichment broth (UB), was compared to the internationally accepted buffered peptone water (BPW). The study was directed towards detection of Salmonella in 100 faecal samples from porcine and 100 neck-skin samples from poultry. The sensitivity (number of positive cases per method among all the positive cases) of the conventional pre-enrichment in BPW was found to be 0.77 for swine and 0.66 for poultry samples, while a combination of the BPW method with parallel pre-enrichment of the same sample in UB resulted in high sensitivity for swine (0.92) and poultry (0.95) samples. A 2-h pre-enrichment in the non-selective Revive, followed by overnight enrichment in selective broth, resulted in a low sensitivity, particularly for the neck-skin samples (0.16, P=0.001). The SEB method in the porcine samples resulted in a sensitivity (0.71) comparable to the standard method (P=0.31). In conclusion, additional pre-enrichment of samples in UB may substantially increase the culture sensitivity. During routine screening of large numbers of samples, it may be advantageous to use SEB rather than standard culturing.     

应用T细胞酶联免疫斑点法诊断人类免疫缺陷病毒感染合并结核潜伏感染的实验研究

目的探讨T细胞酶联免疫斑点法(TSPOT)在我国人类免疫缺陷病毒(HIV)感染人群中用于诊断结核潜伏感染的应用价值。方法应用TSPOT-TB试剂盒对68例明确诊断的HIV感染者血液标本进行结核分枝杆菌(Mtb)特异性T细胞的检测,同时对所有病例做结核菌素纯蛋白生物(PPD)试验。结果在HIV感染者总体、CD4<200/μl和CD4>200/μl各组中,TSPOT检测阳性率分别为67.65%、44.44%和70.69%,PPD试验阳性率分别为41.18%、11.11%和46.55%,其中在HIV感染者总体及CD4>200/μl组中TSPOT检测阳性率均高于PPD试验,差异有统计学意义(P均<0.005)。TSPOT检测在CD4<200/μl组中的阳性率低于CD4>200/μl组,但差异无统计学意义(P>0.05);PPD试验在CD4<200/μl组中的阳性率远低于CD4>200/μl组,差异有统计学意义(P<0.05)。结论TSPOT检测在我国HIV感染合并结核潜伏感染的早期快速诊断中有较大应用价值,尤其是在CD4细胞计数>200/μl的HIV感染人群中,阳性率高于目前常用的PPD试验。PPD试验阳性率受CD4细胞计数水平的显著影响,而T SPOT检测不首次此因素影响。     

LED Light-Induced ROS Differentially Regulates Focal Adhesion Kinase Activity in HaCaT Cell Viability

In this study, changes in cell signaling mechanisms in skin cells induced by various wavelengths and intensities of light-emitting diodes (LED) were investigated, focusing on the activity of focal adhesion kinase (FAK) in particular. We examined the effect of LED irradiation on cell survival, the generation of intracellular reactive oxygen species (ROS), and the activity of various cell-signaling proteins. Red LED light increased cell viability at all intensities, whereas strong green and blue LED light reduced cell viability, and this effect was reversed by NAC or DPI treatment. Red LED light caused an increase in ROS formation according to the increase in the intensity of the LED light, and green and blue LED lights led to sharp increases in ROS formation. In the initial reaction to LEDs, red LED light only increased the phosphorylation of FAK and extracellular-signal regulated protein kinase (ERK), whereas green and blue LED lights increased the phosphorylation of inhibitory-κB Kinase α (IKKα), c-jun N-terminal kinase (JNK), and p38. The phosphorylation of these intracellular proteins was reduced via FAK inhibitor, NAC, and DPI treatments. Even after 24 h of LED irradiation, the activity of FAK and ERK appeared in cells treated with red LED light but did not appear in cells treated with green and blue LED lights. Furthermore, the activity of caspase-3 was confirmed along with cell detachment. Therefore, our results suggest that red LED light induced mitogenic effects via low levels of ROS–FAK–ERK, while green and blue LED lights induced cytotoxic effects via cellular stress and apoptosis signaling resulting from high levels of ROS.