Communication skills utilized by physicians in the pediatric outpatient setting.

BACKGROUND: Effective communication has been shown to increase patient satisfaction. The objective of this study was to describe communication strategies employed by physicians, and determine if physician communication strategies affect caregiver perception of quality or satisfaction with physician communication in a pediatric ambulatory setting. METHODS: This observational study was conducted at the Children's Hospital of Philadelphia and consisted of video recordings of visits that were reviewed by research assistants for physician utilized communication strategies. Caregivers completed surveys on their preferred physician communication qualities, perception of communication quality, and satisfaction with communication. Correlation was performed between types of communication strategy and caregiver satisfaction with communication or perceived quality of communication. T-tests were run to see if there was a significant difference in patient perceived communication and satisfaction scores based on the communication strategies utilized during visits. RESULTS: There were five universally used communication strategies across the 84 clinic visits recorded, including: eye contact, good posture, speaking concisely, providing thorough explanations, and providing summary of next steps. The average number of communication strategies used was 15.95 (σ = 1.50) with physicians using at least 16 of the 18 communication strategies in 62% of the clinic visits. There was no correlation between the number of communication strategies physicians utilized and either the caregiver perception of communication quality score (CPCQ) or communication satisfaction (CS) score. Caregivers who preferred an authoritative approach but perceived a collaborative approach reported lower average CPCQ and CS scores compared to caregivers who had their communication expectations met. DISCUSSION: There are numerous tools designed to help the physician facilitate an effective working relationship with the patient. In our study, the universally used verbal communication strategies are generally recognized as components of an effective communication repertoire. Another part of effective communication is meeting communication expectations with the CS scores suggesting that caregivers felt their communication needs were being met. Dedicating clinical time to understanding this need may help improve the overall clinical experience. CONCLUSION: Physicians utilize many of the suggested communication strategies to help facilitate an effective clinical encounter. Further studies on caregiver communication requirements and meeting caregiver communication expectations are needed.

Determinants of pressure drift in Manoscan(™) esophageal high-resolution manometry system.

BACKGROUND: Manoscan(™) is one of the commonly used high-resolution manometry (HRM) systems with declared measurement accuracy of 1-2 mmHg. However, the accuracy of pressure measurements is limited by development of pressure drift (PD) throughout recording. To date, there has been no systematic investigation to identify the factors contributing to PD. The aim of the present study was to characterize the frequency and magnitude of PD in Manoscan(™) system and identify the factors contributing to PD. METHODS: Records of 560 consecutive clinical esophageal HRM studies recorded by six distinct HRM catheters were retrospectively reviewed. PD was defined as the residual pressure measurement by each sensor immediately after removal of the catheter. Non-parametric locally weighted regression analysis was performed to assess the effect of duration of study, number of prior uses of a catheter, peak and average pressure exposure during a study on the PD. KEY RESULTS: The majority (95%) of clinical manometry studies showed a non-negligible PD of more than 5 mmHg. The overall PD was 13 ± 5 mmHg and the sensor with greatest amount of PD showed 23 ± 12 mmHg of drift. The upper esophageal sphincter showed the highest PD. Average pressure exposure of a sensor throughout the recording was the most important predictor of PD. PD inversely correlated with number of prior uses of a catheter. CONCLUSIONS & INFERENCES: The PD preferentially affects esophageal high-pressure zones, and strongly correlates with 'average pressure exposure' of a sensor during manometry. Available algorithms of the analysis software do not adequately correct the PD.

Polymorphisms in the promoter region of myostatin gene are associated with carcass traits in pigs.

Higher average daily gain, more lean meat yield and less fat yield of porcine carcass increase selling profits for animal producers. Myostatin (MSTN), previously called GDF8, is a member of transforming growth factor-ß (TGF-ß) superfamily. It is a negative regulator for both embryonic development and adult homeostasis of skeletal muscle. In this study, the genotypes of the previously described SNPs MSTN g.435G>A and g.447A>G SNPs in 66 Duroc pigs, 33 Landrace pigs, 180 Duroc × Landrace (DL) pigs and 155 Duroc × Yorkshire × Landrace (DYL) pigs were determined by Taqman SNP Genotyping Assays. For Duroc and Landrace pigs, MSTN g.435GG/g.447AA individual had greater backfat thickness (p < 0.05) than g.435AA/g.447GG individual, whereas MSTN g.435AA/g.447GG had greater meat (p < 0.05) and meat percentage (p < 0.05) than g.435GA/g.447AG individual. For DL and DYL pigs, the MSTN g.435GG/g.447AA animals were greater in backfat at ultrasound 10th rib (p < 0.05) and carcass 10th rib (p < 0.01) than g.435AA/g.447GG individual. The MSTN g.435AA/g.447GG individual also had higher values than g.435GG/g.447AA for anterior-end meat (p < 0.05), posterior-end meat (p < 0.01), total meat weight (p < 0.01) and meat percentage (p < 0.01). This study confirmed evidence that MSTN g.435G>A and g.447A>G affected carcass traits in pigs. The effects of the mutated alleles were additive with the maximal effects resulting from two copies of the mutated allele. Selection for MSTN g.435A/g.447G allele is expected to increase muscle of limb and total meat production and decrease backfat thickness.

Investigation of genetic relationships among Taiwan black pigs and other pig breeds in Taiwan based on microsatellite markers.

The aim of this study was to investigate the genetic relationships between Taiwan black pigs (TBP) and other pig breeds by means of 15 fluorescent-labeled microsatellite markers. DNA from a total of 299 TBP from eight private farms and 234 purebred pigs representing six breeds and one synthetic line was used. Among the 15 microsatellite loci, polymorphism information content (PIC) values were all above 0.500; the numbers of observed alleles were all greater than the numbers of effective alleles (10.1 vs. 4.3 in averages). But 13 of the 15 microsatellite markers significantly deviated from the Hardy-Weinberg equilibrium (HWE); moreover, 13 of the 15 tested populations also deviated from the HWE. The inbreeding coefficient (F(IS)) indicated that two TBP populations (TBP-3 and TBP-4) had heterozygote deficiency (P < 0.01). The pair-wise F(ST), representing the genetic diversity between the two populations, ranged from 0.0332 to 0.3809. Meishan and Taoyuan breeds with black hair were previously considered closely related to TBP; however, the result of genetic relationship refuted this assumption. In conclusion, TBP is more similar to the European than Chinese breeds, and further investigations will need to clarify it more accurately.

Differential gene expression between the porcine morula and blastocyst.

The survival and development of pre-implantation embryos are determinant factors affecting the outcome of animal reproduction. It is essential to transfer the expression of the genetic material from maternal sources, that is the ovum to the zygote before implantation to ensure successful development. Differentiation and transformation of blastomeres initiated during the morula and blastocyst stages is an important step of the embryonic development prior to implantation. We collected morula and early blastocyst samples from pure-bred Landrace pigs in vivo to study the differential gene expression patterns at these two stages. Total RNA was extracted from individual embryos and two rounds of amplification were employed. Two micrograms of antisense RNA, targets, were prepared and hybridized with each of four custom made oligo microarrays representing 24,000 porcine genes. The analyses of replicate hybridizations showed that among the 24,000 genes, 162 genes were expressed fivefold or greater in the morula compared to early blastocysts and 2126 genes were expressed fivefold or greater in early blastocysts compared to the morula. Of these differentially expressed genes, 1429 genes were functionally annotated with related human Gene Ontology terms. In addition to basic metabolic processes, genes related to signal transduction, transportation and cell differentiation were found in both stages and were up-regulated as embryo development proceeded. Real time polymerase chain reaction was utilized to quantify 12 genes differentially expressed in the 2 embryonic stages and validated the reliability of major evidences shown in microarrays. In conclusion, we have obtained a preliminary landscape of genes differentially expressed during the transition from morula to early blastocysts in pigs and showed a generally increased transcriptional activity, perhaps in preparation for implantation. Our results provide an opportunity to study the functions of these genes in relation to the development and survival of pre-implantation porcine embryos.

Regulation of the expression of angiotensin-converting enzyme 2 by polyunsaturated fatty acids in porcine adipocytes.

Using suppression subtractive hybridization technique, we found that 2 novel genes (AEUG1 and AEUG3) were highly expressed in the adipocytes compared with preadipocytes. We then identified that these 2 genes were both angiotensin-converting enzyme 2 (ACE2). We applied 3'RACE (rapid amplification of cDNA end), 5'RACE, and PCR to obtain the full-length porcine ACE2 cDNA sequence. Because eicosanoids derived from PUFA are involved in regulating blood pressure, we hypothesized that PUFA can regulate the expression of the vasodilator ACE2. Preadipocytes from Landrace pigs were induced to differentiate for 4 d, then treated with 50 µM of different PUFA, CLA, arachidonic acid, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), or stearic acid (18:0). Addition of EPA or 18:0 for 48 h did not change the ACE2 mRNA abundance, whereas the treatments of arachidonic acid, CLA, and DHA significantly decreased ACE2 mRNA abundance after 48 h (P ≤ 0.05). Treatment with PUFA did not change (P > 0.05) type I and type II angiotensin receptor mRNA abundance. To further understand how PUFA metabolites affect ACE2 mRNA expression, we inhibited individual enzymes that are involved in eicosanoid production. We found that 3 individual eicosanoid pathway enzyme inhibitors recovered the PUFA effect on the expression of ACE2, indicating these pathways are involved in mediating the PUFA function. In conclusion, we obtained the full-length porcine ACE2 cDNA sequence and found PUFA could downregulate the expression of ACE2 through its metabolites without changing the expression of their receptor in porcine adipocytes.

Visfatin regulates genes related to lipid metabolism in porcine adipocytes.

Visfatin is a visceral adipose tissue-specific adipocytokine that plays a positive role in attenuating insulin resistance by binding to the insulin receptor. Visfatin has been suggested to play a role in the regulation of lipid metabolism and inflammation; however, the mechanism remains unclear. We investigated the effects of visfatin on the regulation of gene expression in cultured porcine preadipocytes and differentiated adipocytes. In preadipocytes, the mRNA abundance of lipoprotein lipase and PPARgamma were significantly increased by visfatin or insulin treatment after 8 d (all P < 0.05). In the presence of insulin, the mRNA abundance of adipocyte fatty acid-binding protein was 24.7-fold greater than in the untreated group (P < 0.05), whereas visfatin alone had no effect on adipocyte fatty acid-binding protein mRNA abundance. Adipocyte differentiation was induced by insulin treatment for 8 d. In differentiated porcine adipocytes, exposure to insulin or visfatin for 24 h increased (P < 0.05) fatty acid synthase mRNA abundance but had no effect on the expression of sterol regulatory element binding-protein 1c mRNA. We also found a 5.8-fold upregulation of IL-6 expression in porcine adipocytes after 24 h of treatment with visfatin (P < 0.05). These results demonstrated that visfatin upregulated lipoprotein lipase expression in preadipocytes, potentially facilitating lipid uptake, and increased the gene expression of fatty acid synthase in differentiated adipocytes to potentially enhance lipogenic activity. Furthermore, visfatin can upregulate IL-6 expression in differentiated porcine adipocytes. The information presented in this study provides insights into the roles of visfatin in lipid metabolism in pigs.

Abundantly expressed hepatic genes and their differential expression in liver of prelaying and laying geese.

Geese have a short egg-laying period and a low egg production rate. To induce and maintain egg laying, genes related to generating hepatic lipid for yolk deposition should be adequately expressed. Liver mRNA from 6 laying geese was extracted and used for construction of a full-length enriched cDNA library. About 2,400 clones containing gene sequences were determined and National Center for Biotechnology Information Gallus gallus Gene Index databases were used to compare and analyze these sequences. Ten highly expressed genes were selected to determine the differential expression between laying and prelay goose liver. Tissue distribution data showed that very low density apolipoprotein II, liver type fatty acid binding protein, vitellogenin I, and vitellogenin II transcripts were specifically expressed in the liver of laying geese. Ovoinhibitor, preproalbumin, alpha-2-hs-glycoprotein, and vitamin D binding protein mRNA were highly expressed in the liver and to a lesser extent in other tissues. Ovotransferrin mRNA was expressed in liver, ovary, oviduct, shell gland, brain, and adipose tissues. The concentration of transthyretin mRNA was high in the liver and brain. The mRNA concentrations of liver type fatty acid binding protein, alpha-2-hs-glycoprotein, and transthyretin in the livers of laying and prelay geese were not different. The concentrations of hepatic ovotransferrin, ovoinhibitor, preproalbumin, very low density apolipoprotein II, vitellogenin I, vitellogenin II, and vitamin D binding protein mRNA were higher in the liver of laying geese than in prelay geese, suggesting that these genes may be involved in laying function or lipid metabolism related to egg formation.

Identification and sequencing of remnant messenger RNAs found in domestic swine (Sus scrofa) fresh ejaculated spermatozoa.

The existence of specific messenger RNA remnants contained within freshly ejaculated spermatozoa was described in several species. Those investigations, using high-throughput techniques to screen the population of transcripts in ejaculated spermatozoa, were limited to the probes which mostly derived from nucleic acids of testicular tissues of either human or mice. The objective of this study was to investigate mRNA remnants from ejaculated spermatozoa of the domestic swine (Sus scrofa), a valuable model for biomedical research. A non-redundant 5'-end complementary DNA library was generated from swine ejaculated spermatozoa. After sequence quality verification, 4562 clones remained. These clones were then clustered and assembled into 514 unique sequences including 188 contigs (36.58%) and 326 singletons (63.42%), representing those clusters containing at least two clones and those clusters without having enough similarity with other clones. These unique gene sequences were annotated in Gene Ontology (GO) hierarchy; they included biological processes (38.7%), molecular functions (39.1%) and cellular components (40.3%). Based on the analysis, a broad spectrum of messenger RNAs existed in swine ejaculated spermatozoa and was closely correlated with nucleic acid binding, structural modifications, and transcriptional regulation. All of these categories are considered to have profound effects on the male reproductive system. Therefore, our work provides initial results on potential spermatozoal gene expression for future studies regarding the tightly regulated spermiogenic processes and later fertilization events.

Docosahexaenoic acid regulates adipogenic genes in myoblasts via porcine peroxisome proliferator-activated receptor gamma.

The nuclear transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma) triggers adipocyte differentiation by regulating lipogenic genes. A ligand for PPARgamma is necessary to activate PPARgamma function. Fatty acids are potential ligands for PPARgamma activation. The current experiment was designed to determine the potential for individual fatty acids to activate porcine PPARgamma ectopically expressed in myoblasts. The expression of adipocyte fatty acid binding protein (aP2) and adiponectin in myoblasts stably expressing porcine PPARgamma was increased when docosahexaenoic acid (DHA) was added to the adipogenic medium. The response was positively related to DHA concentration and suggests that DHA may bind to and activate porcine PPARgamma, leading to increased expression of aP2 and adiponectin. The conditioned media collected from myoblasts expressing PPARgamma between d 3 and 6 or between d 6 and 9, but not DHA itself, activated the aP2 gene promoter-driven luciferase activity. These results suggest that a metabolite of DHA is the ligand binding to and activating porcine PPARgamma. The metabolite and pathway for its production are currently unknown.

Expressed transcripts associated with high rates of egg production in chicken ovarian follicles.

The purpose of this study was to characterize differentially expressed transcripts associated with varying rates of egg production in Taiwan country chickens. Ovarian follicles were isolated from two strains of chicken which showed low (B) or high (L2) rates of egg production, then processed for RNA extraction and cDNA library construction. Three thousand and eight forty clones were randomly selected from the cDNA library and amplified by PCR, then used in microarray analysis. Differentially expressed transcripts (P<0.05, log(2)> or = 1.75) were sequenced, and aligned using GenBank. This analysis revealed 20 non-redundant sequences which corresponded to known transcripts. Eight transcripts were expressed at a higher level in ovarian tissue prepared from chicken strain B, and 12 transcripts were expressed at a higher level in L2 birds. These differential patterns of expression were confirmed by semi-quantitative RT-PCR. We show that transcripts of cyclin B2 (cycB2), ferritin heavy polypeptide 1 (FTH1), Gag-Pol polyprotein, thymosin beta4 (TB4) and elongation factor 1 alpha1 (EEF1A1) were enriched in B strain ovarian follicles. In contrast, thioredoxin (TXN), acetyl-CoA dehydrogenase long chain (ACADL), inhibitor of growth family member 4 (ING4) and annexin II (ANXA2) were expressed in at higher levels in the L2 strain. We suggest that our approach may lead to the isolation of effective molecular markers that can be used in selection programs in Taiwan country chickens.

Abundantly expressed genes in pig adipose tissue: an expressed sequence tag approach.

Adipose tissue plays a critical role in metabolism, storage, and release of fatty acids in mammals. Construction of a full-length cDNA library is an effective way to understand the functional expression of genes in adipose tissue, and in addition, novel genes for further research can be found in the library. In this study, adipose tissue RNA was extracted from three 18-mo-old Lee-Sung pigs. The mRNA was isolated, reverse transcribed, and used to construct a cDNA library. After transformation, 2,880 clones were selected and sequenced. Cluster analysis was performed, and the assembled contig of each cluster was subjected to search against DNA sequences in the nucleotide databases (NCBINR/TIGRGI). These sequences were clustered into 1,527 unique sequences; 80% of the sequences were categorized as known genes, and 20% of the sequences were categorized as unknown genes. In this adipose tissue cDNA library, approximately 16% of the genes contained full-length sequences with start and stop codons. Gene ontology analysis was performed to indicate the possible functions of these genes. Genes associated with mitochondrial function were abundant and represented 10% of the total. Several fatty acid transport genes and stearoyl coenzyme A desaturase were among the most abundant genes expressed. Tissue distribution of several abundant genes was analyzed by northern analysis, and many of these genes were transcribed in porcine adipose tissue in high copy number. Our full-length sequence data and tissue distribution data can be used to decipher the functional roles exhibited by the adipocyte under various perturbations via endocrine, environmental, genetic, nutritional, pharmacological, or physiological manipulations.

DnaK dependence of mutant ethanol oxidoreductases evolved for aerobic function and protective role of the chaperone against protein oxidative damage in Escherichia coli.

The adhE gene of Escherichia coli encodes a multifunctional ethanol oxidoreductase (AdhE) that catalyzes successive reductions of acetyl-CoA to acetaldehyde and then to ethanol reversibly at the expense of NADH. Mutant JE52, serially selected for acquired and improved ability to grow aerobically on ethanol, synthesized an AdhE(A267T/E568K) with two amino acid substitutions that sequentially conferred improved catalytic properties and stability. Here we show that the aerobic growth ability on ethanol depends also on protection of the mutant AdhE against metal-catalyzed oxidation by the chaperone DnaK (a member of the Hsp70 family). No DnaK protection of the enzyme is evident during anaerobic growth on glucose. Synthesis of DnaK also protected E. coli from H2O2 killing under conditions when functional AdhE is not required. Our results therefore suggest that, in addition to the known role of protecting cells against heat stress, DnaK also protects numerous kinds of proteins from oxidative damage.

Effects of single nucleotide polymorphisms in the 5'-flanking region of heat shock protein 70.2 gene on semen quality in boars.

This study aims to elucidate the effects of single nucleotide polymorphisms (SNPs) in the 5'-flanking region of porcine heat shock protein 70.2 gene (HSP70.2) on semen quality in boars. Genomic DNA isolated from 55 boars (41 Duroc, nine Landrace, and five Yorkshire) was subjected to PCR amplification of the 5'-flanking region of HSP70.2. The nucleotide sequences were determined by automated sequencing. Five SNPs (sites 44, 232, 250, 345, and 393) were detected in this region. Semen quality was evaluated in terms of sperm motility, percentage of normal sperm, percentage of sperm with proximal plasma droplet, percentage of abnormal sperm, sperm concentration, semen volume per ejaculate and total sperm number per ejaculate. The effect of the SNPs on semen quality was evaluated based on breed-corrected data within a season. During the cool season, the sperm motility of boars with AA genotype at the 232 site was significantly higher than that of boars with CC genotype (P<0.05). Meanwhile, boars with AC genotype at the 232 site had higher total sperm number per ejaculate than did those with CC genotype. In the hot season, heterozygotes at both the 232 and 250 sites had significantly higher total sperm number of per ejaculate than AA homozygotes (P<0.05). Semen volume of boars with TT and TC genotypes at the 345 site was significantly larger than that of those with CC genotype (P<0.05). Meanwhile, semen quality for boars with TT genotype at the 345 site was significantly higher than that of boars with TC or CC genotype (P<0.05), that is the semen contained higher percentages of normal sperm and lower percentages of abnormal sperm or sperm with proximal plasma droplets. Results herein suggest that the SNPs in the 5'-flanking region of porcine HSP70.2 are associated with semen quality traits in the hot season.

A comparison of effectiveness and cost between two models of care for individuals with schizophrenia living in Taiwan.

Schizophrenia is a chronic disease that places tremendous costs and burden on patients, families, and communities. The purpose of this study was to compare the cost and effectiveness of a hospital-based home care model and a traditional community care model for schizophrenia in Taiwan using six principles of cost-effectiveness analysis. Based on the health care provider's analytic perspective, four effectiveness indicators and four service costs were identified and measured, and the ratio of average cost value to effectiveness score for each patient was calculated. According to that ratio, the hospital-based home care model was more cost-effective. The results suggest that the hospital-based outreach home care model is a cost-effective way to care for patients and their family in the community.

Redox signal transduction by the ArcB sensor kinase of Haemophilus influenzae lacking the PAS domain.

The Arc (anoxic redox control) two-component signal transduction system of Escherichia coli, which comprises the tripartite ArcB sensor kinase and the ArcA response regulator, modulates the expression of numerous operons in response to redox conditions of growth. We demonstrate that the arcA and arcB genes of Haemophilus influenzae specify a two-component system. The Arc proteins of the two bacterial species sufficiently resemble each other that they can participate in heterologous transphosphorylation in vitro. Moreover, the Arc system of H. influenzae mediates transcriptional control according to the redox condition of growth both autologously in its own host and homologously in E. coli, indicating a high degree of functional conservation of the signal transduction system. The H. influenzae ArcB, however, lacks the PAS domain present in the region of E. coli ArcB linking the transmembrane to the cytosolic catalytic domains. Because the PAS domain participates in signal reception in a variety of sensory proteins, including sensors of molecular oxygen and redox state, a similar role was previously ascribed to it in ArcB. Our results demonstrate that the ArcB protein of H. influenzae mediates signal transduction in response to redox conditions of growth despite the absence of the PAS domain.

Radionuclide imaging of hepatic and biliary disease.

This article will focus on common clinical applications of scintigraphy in focal hepatic lesions, acute cholecystitis, biliary dyskinesia, biliary obstruction, postoperative liver and biliary tract, and neonatal cholestasis. The utility of positron emission tomography will also be addressed.

Isotope imaging for metastatic thyroid cancer.

Many isotopes are available for imaging patients with suspected thyroid cancer recurrence and metastases. TSH-stimulated low-dose 131I whole-body scanning with serum thyroglobulin either by standard LT4 withdrawal or rhTSH stimulation is the preferred test for monitoring patients without palpable disease or elevated serum thyroglobulin on LT4 therapy (Fig. 5). This approach has the advantage of finding disease that may be amenable to 131I therapy, although low-dose 131I scans are less sensitive than are scans with other imaging agents. 123I has better imaging characteristics than 131I and has been shown to be equivalent or superior to low-dose 131I in recent studies. As the availability of 123I increases and the cost decreases, this agent may replace 131I in imaging for recurrent or metastatic thyroid cancer. Patients who have an elevated serum thyroglobulin on LT4 therapy or after TSH stimulation but have a negative low-dose 131I scan require other imaging procedures to find the suspected disease. The authors currently perform a sensitive neck ultrasound to look for surgically remediable disease and consider a noncontrast CT scan of the chest to look for small pulmonary metastases that poorly concentrate low doses of 131I (Fig. 5). Fluoro-18-deoxyglucose PET, 99mTc MIBI, 201Tl, and 99mTc tetrofosmin are primarily useful in the setting of a negative whole-body 131I scan and elevated serum thyroglobulin. 18FDG-PET seems to have the highest sensitivity in this setting and would be the preferred imaging agent, but availability and cost are major issues (Fig. 5). Although some researchers have advocated these radiopharmaceuticals as first-line agents replacing 131I, there is little support for this position. This approach to imaging is not cost-effective because positive scans in these patients would most likely require 131I scintigraphy to determine whether the lesions are amenable to radioiodine therapy. 99mTc pertechnetate, 99mTc furifosmin, and somatostatin receptor scintigraphy have a limited role in imaging for recurrent or metastatic differentiated thyroid carcinoma. In choosing among 99mTc MIBI, 201Tl, and 99mTc tetrofosmin, the technetium label of sestamibi and tetrofosmin results in better image quality and faster imaging than 201Tl. Although 99mTc sestamibi and 99mTc tetrofosmin have not been compared in a large series, the higher tumor-to-background ratio and consistently high sensitivities of 99mTc tetrofosmin suggest that it could potentially have additional value over 99mTc sestamibi, but there is still limited experience with 99mTc tetrofosmin.

Quinones as the redox signal for the arc two-component system of bacteria.

The Arc two-component signal transduction system mediates adaptive responses of Escherichia coli to changing respiratory conditions of growth. Under anaerobic conditions, the ArcB sensor kinase autophosphorylates and then transphosphorylates ArcA, a global transcriptional regulator that controls the expression of numerous operons involved in respiratory or fermentative metabolism. We show that oxidized forms of quinone electron carriers act as direct negative signals that inhibit autophosphorylation of ArcB during aerobiosis. Thus, the Arc signal transduction system provides a link between the electron transport chain and gene expression.