Fatigue in systemic lupus: the role of disease activity and its correlates.

OBJECTIVES: Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that leads to a variety of negative health outcomes resulting from inflammation in various organ systems. Although treatment continues to advance, fatigue remains one of the most salient, poorly understood and addressed patient complaints. Understanding the mechanisms of fatigue can help guide the development of interventions to improve health outcomes. The aim of this research was to evaluate the contribution of six variables (disease activity, insomnia, depression, stress, pain and physical health) to fatigue in SLE without concomitant fibromyalgia (FM). METHODS: A total of 116 ethnically diverse, primarily female participants (91%) with SLE, receiving care at university medical centers, completed assessments of disease activity and quality of life outcomes (FACIT-FT, Insomnia Severity Index, Perceived Stress Scale (PSS-4), Pain Inventory, Depression-PHQ-9, and LupusPRO-physical function). All patients met the American College of Rheumatology classification criteria for SLE and did not have a known diagnosis of FM. Multivariate linear and stepwise regression analyses were conducted with fatigue (FACIT-FT) as the dependent variable, and the above six variables as independent variables. RESULTS: Mean (SD) age was 39.80 (13.87) years; 50% were African American, 21% Caucasian, 13% Hispanic, 9% Asian and 8% other. Mean (SD) FACIT-FT was 20.09 (12.76). Collectively, these six variables explained 57% of the variance in fatigue. In the multivariate model, depression, stress and pain were significantly and independently associated with fatigue, but not disease activity, sleep or physical health. Stress had the largest effect on fatigue (ß 0.77, 95% CI 0.17-1.38, p = 0.01), followed by depression (ß 0.66, 95% CI 0.21-1.10, p = 0.005). On stepwise regression analysis, only stress, depression and pain were retained in the model, and collectively explained 56% of the variance in fatigue. All three remained independent correlates of fatigue, with the largest contribution being stress (ß 0.84, 95% CI 0.27-1.42, p = 0.005), followed by depression (ß 0.79, 95% CI 0.44-1.14, p < 0.001) with fatigue. CONCLUSION: Stress, depression and pain are the largest independent contributors to fatigue among patients with SLE, without concurrent FM. Disease activity, sleep and physical health were not associated with fatigue. The evaluation of stress, depression and pain needs to be incorporated during assessments and clinical trials of individuals with SLE, especially within fatigue. This stress-depression-fatigue model requires further validation in longitudinal studies and clinical trials. Significance and innovation: • Disease activity, sleep, pain, stress, depression, and physical health have been reported individually to be associated with fatigue in lupus. This analysis evaluated the role of each and all of these six variables collectively in fatigue among patients with SLE without a known diagnosis of FM. • Disease activity, sleep and physical health were not significantly related to fatigue, but depression, stress and pain were. • The results emphasize the need to evaluate and treat fatigue in individuals with SLE utilizing a biopsychosocial approach, particularly in the realm of clinical trials. Behavioral medicine interventions are shown to be most effective for the treatment of depression, stress and pain.

Validation of the LupusPRO version 1.8: an update to a disease-specific patient-reported outcome tool for systemic lupus erythematosus.

Objectives LupusPRO has shown good measurement properties as a disease-specific patient-reported outcome tool in systemic lupus erythematosus (SLE). For the purpose of clinical trials, the version 1.7 (v1.7) domain of Pain-Vitality was separated into distinct Pain, Vitality and Sleep domains in v1.8, and the psychometric properties examined. Methods A total of 131 consecutive SLE patients were self-administered surveys assessing fatigue (FACIT, SF-36), pain (Pain Inventory, SF-36), insomnia (Insomnia Severity Index), emotional health (PHQ-9, SF-36) and quality of life (SF-36, LupusPRO) at routine care visits. Internal consistency reliability (ICR) for each domain was obtained using Cronbach's alpha. The convergent construct validity of LupusPRO domains with corresponding SF-36 domains or tools were tested using Spearman correlation. Varimax rotations were conducted to assess factor structures of the LupusPRO v1.8. Results Mean (SD) age was 40.04 (14.10) years. Scores from the LupusPRO-Sleep domain strongly correlated with insomnia scores, while LupusPRO-Vitality correlated strongly with fatigue (FACIT) and SF-36 vitality. The LupusPRO-Pain domain correlated strongly with pain (SF36 Bodily-Pain, Pain Inventory) scores. Similarly, the LupusPRO domains of Physical and Emotional Health had significant correlations with corresponding SF-36 domains. The ICR for HRQoL and non-HRQoL were 0.96 and 0.81. LupusPRO (domains HRQoL and QoL) scores correlated with disease activity. Principal component analysis included seven factor loadings presenting for the HRQOL subscales (combined Sleep, Vitality, and Pain), and three factors for the NHRQoL (Combined Coping and Social Support). Conclusions LupusPRO v1.8 (including its Sleep, Vitality, and Pain domains) has acceptable reliability and validity. Use of LupusPRO as an outcome measure in clinical trials would facilitate responsiveness assessment.

Seasonal variation of Pseudomonas aeruginosa in culture positive otitis externa in South East England.

Otitis externa is the inflammation of the external auditory canal. The disease is common and shows a seasonal variation with a greater incidence in warmer months. Pseudomonas aeruginosa is a common pathogen in otitis externa and in this retrospective study, we show a corresponding seasonal variation in the proportional incidence of P. aeruginosa isolates from otitis externa in South East England. In total 7770 patients were diagnosed with otitis externa over a period of 9 years from January 2008 to December 2016. P. aeruginosa was isolated from 2802 patients (proportional incidence of 36%). Incidence was higher in the months of August, September and October and in patients between 5 and 15 years of age. We postulate a combination of increased contact with water during warm weather in the holiday season and increased rainfall in the preceding season as a putative mechanism for the seasonal trends.

Ephaptic coupling rescues conduction failure in weakly coupled cardiac tissue with voltage-gated gap junctions.

Electrical conduction in cardiac tissue is usually considered to be primarily facilitated by gap junctions, providing a pathway between the intracellular spaces of neighboring cells. However, recent studies have highlighted the role of coupling via extracellular electric fields, also known as ephaptic coupling, particularly in the setting of reduced gap junction expression. Further, in the setting of reduced gap junctional coupling, voltage-dependent gating of gap junctions, an oft-neglected biophysical property in computational studies, produces a positive feedback that promotes conduction failure. We hypothesized that ephaptic coupling can break the positive feedback loop and rescue conduction failure in weakly coupled cardiac tissue. In a computational tissue model incorporating voltage-gated gap junctions and ephaptic coupling, we demonstrate that ephaptic coupling can rescue conduction failure in weakly coupled tissue. Further, ephaptic coupling increased conduction velocity in weakly coupled tissue, and importantly, reduced the minimum gap junctional coupling necessary for conduction, most prominently at fast pacing rates. Finally, we find that, although neglecting gap junction voltage-gating results in negligible differences in well coupled tissue, more significant differences occur in weakly coupled tissue, greatly underestimating the minimal gap junctional coupling that can maintain conduction. Our study suggests that ephaptic coupling plays a conduction-preserving role, particularly at rapid heart rates.

Memory in a fractional-order cardiomyocyte model alters properties of alternans and spontaneous activity.

Cardiac memory is the dependence of electrical activity on the prior history of one or more system state variables, including transmembrane potential (Vm), ionic current gating, and ion concentrations. While prior work has represented memory either phenomenologically or with biophysical detail, in this study, we consider an intermediate approach of a minimal three-variable cardiomyocyte model, modified with fractional-order dynamics, i.e., a differential equation of order between 0 and 1, to account for history-dependence. Memory is represented via both capacitive memory, due to fractional-order Vm dynamics, that arises due to non-ideal behavior of membrane capacitance; and ionic current gating memory, due to fractional-order gating variable dynamics, that arises due to gating history-dependence. We perform simulations for varying Vm and gating variable fractional-orders and pacing cycle length and measure action potential duration (APD) and incidence of alternans, loss of capture, and spontaneous activity. In the absence of ionic current gating memory, we find that capacitive memory, i.e., decreased Vm fractional-order, typically shortens APD, suppresses alternans, and decreases the minimum cycle length (MCL) for loss of capture. However, in the presence of ionic current gating memory, capacitive memory can prolong APD, promote alternans, and increase MCL. Further, we find that reduced Vm fractional order (typically less than 0.75) can drive phase 4 depolarizations that promote spontaneous activity. Collectively, our results demonstrate that memory reproduced by a fractional-order model can play a role in alternans formation and pacemaking, and in general, can greatly increase the range of electrophysiological characteristics exhibited by a minimal model.

Prenatal sex hormones, digit ratio, and face shape in adult males.

OBJECTIVES: Several reports have demonstrated a relationship between second to fourth digit ratio (2D:4D) and facial shape, suggesting that prenatal sex hormones play a role in the development of the craniofacial complex. Using 3D surface imaging and geometric morphometrics, we test the hypothesis that decreased digit ratio (indicative of increased prenatal androgen exposure) is associated with a more masculine facial phenotype. METHODS: 3D facial surface images and digit measures were collected on a sample of 151 adult males. Facial landmarks collected from the images were aligned by Procrustes superimposition and the resulting shape coordinates regressed on 2D:4D. Variations in facial shape related to 2D:4D were visualized with deformable surface warps. RESULTS: A significant statistical relationship was observed between facial shape variation and 2D:4D (p = 0.0084). Lower 2D:4D ratio in adult males was associated with increased facial width relative to height, increased mandibular prognathism, greater nasal projection, and increased upper and lower lip projection. CONCLUSIONS: A statistical relationship between 2D:4D and facial shape in adult males was observed. Faces tended to look more masculine as 2D:4D decreased, suggesting a biologically plausible link between prenatal androgen exposure and the development of male facial characteristics.

Phenotype Harmonization in the GLIDE2 Oral Health Genomics Consortium.

Genetic risk factors play important roles in the etiology of oral, dental, and craniofacial diseases. Identifying the relevant risk loci and understanding their molecular biology could highlight new prevention and management avenues. Our current understanding of oral health genomics suggests that dental caries and periodontitis are polygenic diseases, and very large sample sizes and informative phenotypic measures are required to discover signals and adequately map associations across the human genome. In this article, we introduce the second wave of the Gene-Lifestyle Interactions and Dental Endpoints consortium (GLIDE2) and discuss relevant data analytics challenges, opportunities, and applications. In this phase, the consortium comprises a diverse, multiethnic sample of over 700,000 participants from 21 studies contributing clinical data on dental caries experience and periodontitis. We outline the methodological challenges of combining data from heterogeneous populations, as well as the data reduction problem in resolving detailed clinical examination records into tractable phenotypes, and describe a strategy that addresses this. Specifically, we propose a 3-tiered phenotyping approach aimed at leveraging both the large sample size in the consortium and the detailed clinical information available in some studies, wherein binary, severity-encompassing, and "precision," data-driven clinical traits are employed. As an illustration of the use of data-driven traits across multiple cohorts, we present an application of dental caries experience data harmonization in 8 participating studies (N = 55,143) using previously developed permanent dentition tooth surface-level dental caries pattern traits. We demonstrate that these clinical patterns are transferable across multiple cohorts, have similar relative contributions within each study, and thus are prime targets for genetic interrogation in the expanded and diverse multiethnic sample of GLIDE2. We anticipate that results from GLIDE2 will decisively advance the knowledge base of mechanisms at play in oral, dental, and craniofacial health and disease and further catalyze international collaboration and data and resource sharing in genomics research.

Control and management of multidrug resistant Acinetobacter baumannii: A review of the evidence and proposal of novel approaches.

Hospital-acquired infections are on the rise and are a substantial cause of clinical and financial burden for healthcare systems. While infection control plays a major role in curtailing the spread of outbreak organisms, it is not always successful. One organism of particular concern is Acinetobacter baumannii, due to both its persistence in the hospital setting and its ability to acquire antibiotic resistance. A. baumannii has emerged as a nosocomial pathogen that exhibits high levels of resistance to antibiotics, and remains resilient against traditional cleaning measures with resistance to Colistin increasingly reported. Given the magnitude and costs associated with hospital acquired infections, and the increase in multidrug-resistant organisms, it is worth re-evaluating our current approaches and looking for alternatives or adjuncts to traditional antibiotics therapies. The aims of this review are to look at how this organism is spread within the hospital setting, discuss current treatment modalities, and propose alternative methods of outbreak management.

Origins.

The farthest of the galaxies that can be seen through the large ground-based telescopes of modern astronomy, such as those on La Palma in the Canary Islands, are so far away that they appear as they did close to the time of the origin of the universe, perhaps some 10 billion years ago. Much has been learned, and much has still to be learned, about the young universe from optical and radio telescopes, but these instruments cannot be used to look directly at the universe in its first few hundred thousand years. Instead, they are used to search the relatively recent past for relics of much earlier times. Together with experiments planned for the next generation of elementary particle accelerators, astronomical observations should continue to extend what is known about the universe backward in time to the Big Bang and may eventually help to reveal the origins of the physical laws that govern the universe.

Biology teaching.

In Mark Crawford's story "Budget crunch stalls Super Collider" (News & Comment, 1 Apr., p. 17) the caption accompanying the photograph was incorrect. The superconducting magnet pictured was 4.5 meters long, not 17 meters, as stated.

Face shape of unaffected parents with cleft affected offspring: combining three-dimensional surface imaging and geometric morphometrics.

OBJECTIVE: Various lines of evidence suggest that face shape may be a predisposing factor for non-syndromic cleft lip with or without cleft palate (CL/P). In the present study, 3D surface imaging and statistical shape analysis were used to evaluate face shape differences between the unaffected (non-cleft) parents of individuals with CL / P and unrelated controls. METHODS: Sixteen facial landmarks were collected from 3D captures of 80 unaffected parents and 80 matched controls. Prior to analysis, each unaffected parent was assigned to a subgroup on the basis of prior family history (positive or negative). A geometric morphometric approach was utilized to scale and superimpose the landmark coordinate data (Procrustes analysis), test for omnibus group differences in face shape, and uncover specific modes of shape variation capable of discriminating unaffected parents from controls. RESULTS: Significant disparity in face shape was observed between unaffected parents and controls (p < 0.01). Notably, these changes were specific to parents with a positive family history of CL/P. Shape changes associated with CL/P predisposition included marked flattening of the facial profile (midface retrusion), reduced upper facial height, increased lower facial height, and excess interorbital width. Additionally, a sex-specific pattern of parent-control difference was evident in the transverse dimensions of the nasolabial complex. CONCLUSIONS: The faces of unaffected parents from multiplex cleft families displayed meaningful shape differences compared with the general population. Quantitative assessment of the facial phenotype in cleft families may enhance efforts to discover the root causes of CL/P.

Perceptions and Attitudes toward Data Sharing among Dental Researchers.

INTRODUCTION: Increasing attention is being given to the roles of data management and data sharing in the advancement of research. This study was undertaken to explore opinions and past experiences of established dental researchers as related to data sharing and data management. METHODS: Researchers were recruited from the International Association for Dental Research scientific groups to complete a survey consisting of Likert-type, multiple-choice, and open-ended questions. RESULTS: All 42 respondents indicated that data sharing should be promoted and facilitated, but many indicated reservations or concerns about the proper use of data and the protection of research subjects. Many had used data from data repositories and received requests for data originating from their studies. Opinions varied regarding restrictions such as requirements to share data and the time limits of investigator rights to keep data. Respondents also varied in their methods of data management and storage, with younger respondents and those with higher direct costs of their research tending to use dedicated experts to manage their data. DISCUSSION: The expressed respondent support for research data sharing, with the noted concerns, complements the idea of developing managed data clearinghouses capable of promoting, managing, and overseeing the data-sharing process. KNOWLEDGE TRANSFER STATEMENT: Researchers can use the results of this study to evaluate and improve management and sharing of research data. By encouraging and facilitating the data-sharing process, research can advance more efficiently, and research findings can be implemented into practice more rapidly to improve patient care and the overall oral health of populations.

Validation of the Vectra H1 portable three-dimensional photogrammetry system for facial imaging.

Three-dimensional (3D) surface imaging using stereophotogrammetry has become increasingly popular in clinical settings, offering advantages for surgical planning and outcome evaluation. The handheld Vectra H1 is a low-cost, highly portable system that offers several advantages over larger stationary cameras, but independent technical validation is currently lacking. In this study, 3D facial images of 26 adult participants were captured with the Vectra H1 system and the previously validated 3dMDface system. Using error magnitude statistics, 136 linear distances were compared between cameras. In addition, 3D facial surfaces from each system were registered, heat maps generated, and global root mean square (RMS) error calculated. The 136 distances were highly comparable across the two cameras, with an average technical error of measurement (TEM) value of 0.84mm (range 0.19-1.54mm). The average RMS value of the 26 surface-to-surface comparisons was 0.43mm (range 0.33-0.59mm). In each case, the vast majority of the facial surface differences were within a ±1mm threshold. Areas exceeding ±1mm were generally limited to facial regions containing hair or subject to facial microexpressions. These results indicate that 3D facial surface images acquired with the Vectra H1 system are sufficiently accurate for most clinical applications.

Taurocholate transport by rat intestinal basolateral membrane vesicles. Evidence for the presence of an anion exchange transport system.

The transport of bile acid was studied in basolateral membrane vesicles isolated from rat small intestine. Taurocholate transport into an osmotically reactive intravesicular space was Na+ independent. The uptake of taurocholate in jejunal and ileal vesicles preloaded with sulfate was stimulated with respect to uptake in unpreloaded vesicles. Glycocholate inhibited the transstimulation of taurocholate uptake by sulfate. Sulfate and taurocholate uptake in ileal vesicles preloaded with bicarbonate was stimulated with respect to uptake in unpreloaded vesicles. Taurocholate inhibited the transstimulation of sulfate uptake by bicarbonate. When ileal vesicles were loaded with p-aminohippurate, an early transstimulation of taurocholate was found that exceeded equilibrium uptake, was insensitive to a K+ diffusion potential, and was cis-inhibited by taurocholate, glycocholate, pyruvate, p-aminohippurate, probenecid, chloride, sulfate, and bicarbonate. These data indicate the presence of an anion exchanger in intestinal basolateral membrane vesicles that may be involved in the exit of bile acids from the enterocyte.

Dental Decay Phenotype in Nonsyndromic Orofacial Clefting.

Although children with oral clefts have a higher risk for dental anomalies when compared with the general population, prior studies have shown conflicting results regarding their dental decay risk. Also, few studies have assessed dental decay risk in unaffected relatives of children with clefts. Thus, the question of increased risk of dental decay in individuals with oral clefts or their unaffected relatives is still open for empirical investigation. This study characterizes dental decay in the largest international cohort to date of children with nonsyndromic clefts and their relatives, as compared with controls, and it addresses whether families with oral clefts have a significantly increased risk for dental decay versus the general population. A total of 3,326 subjects were included: 639 case probands, 1,549 unaffected relatives, and 1,138 controls. Decay was identified from in-person dental examinations or intraoral photographs. Case-control differences were tested with regression analysis. No significant differences were shown in percentage decayed and filled teeth and decayed teeth in the primary dentition (dft, dt) and permanent dentition (DFT, DT) in cases versus controls. In the cleft region, no significant differences were seen in primary or permanent decay (dt, DT) when compared with controls. No difference was found with regard to cleft type and percentage dft, dt, DFT, and DT in case probands. Nonsignificant differences were found in unaffected siblings and parents versus controls (primary and permanent dentitions). Collectively, these findings indicate that individuals with nonsyndromic oral clefts and their families do not have a higher dental decay risk as compared with the general population. These results suggest that either genetic or environmental factors underlying a higher susceptibility for dental anomalies do not increase caries risk or that the seemingly higher risk for dental decay associated with increased dental anomalies in case probands may be superseded by possible greater access to dental care.

The patient with heart disease and the cardiovascular physician and surgeon: 1958-1983.

The patient with heart disease and the physician providing cardiovascular health care have experienced dramatic change since the American College of Cardiology first published its journal 25 years ago. During the decade before 1958, cardiology and cardiovascular surgery emerged as specialties. Surgery by closed techniques flourished and open heart surgery began. Since 1958, spectacular progress has occurred. Closed chest massage and defibrillation, electronic monitoring, advances in electrophysiology and a new pharmacology have changed cardiology. The coronary care unit has evolved into a comprehensive coronary care system. Pacemakers, myocardial revascularization and open heart surgery have become commonplace and percutaneous angioplasty an option. As custodians of cardiology's historic advances, the cardiologist and cardiovascular surgeon are cast in a role of decision maker and problem solver. Today's diagnostic and therapeutic cardiology, used appropriately, has great potential for good--used inappropriately, for great harm. The patient has the right to expect the physician to act objectively and appropriately in dealing with problems that may threaten his or her livelihood or life. The physician who does less is an unworthy heir to cardiology's great legacy of 1983.

Factors regulating yolk sac hematopoiesis in diffusion chambers: various types of sera, cyclophosphamide, irradiation and long-term culture.

A series of studies were conducted using suspensions of murine 10 1/2 day yolk sac cells, cultured in diffusion chambers (DC), to evaluate the effects of several variables on cell growth and differentiation. The variables evaluated were: treatment of chamber recipients with cyclophosphamide (Cy) or sublethal total body irradiation (TBI), culture medium supplementation with different sera, and long-term culture. The growth of cells in Cy- and TBI-groups was parallel to that of the control group (C) until day 7 of culture. Thereafter, cells in the chambers of each group proliferated at a different rate. Whereas, cell growth in Cy-hosts was significantly greater than in C-hosts, growth of TBI-hosts was less than that in C-hosts. Horse serum supported chamber cellularity better than syngeneic mouse serum or fetal calf serum. Long-term cultures showed an increase in cell numbers until day 56, followed by a steady decrease to day 70, reaching a new level that was maintained until day 98. By day 14 of culture, and throughout the long-term culture study, there was no difference in the pattern of differentiation of DC cultured yolk sac cells. Regardless of the type of host treatment or culture medium the cells harvested were macrophages, plasma cells and lymphocytes.

Hemopoiesis in the splenectomized-pregnant mouse following low-dose total-body irradiation.

The effect of splenectomy (SPLX) and total-body irradiation (TBI) (50-200 rad) on virgin and pregnant mouse hemopoiesis was studied, using peripheral blood hemogram values and femoral marrow hemopoietic progenitor cell activity (i.e., CFUE, BFUE, and GM-CFC). The SPLX-maternal red cell counts and hematocrit values were lower than those of SPLX-virgin mice, reflecting the anemia of pregnancy. But the white cell counts of both SPLX-virgin and SPLX-day-14.5 pregnant mice were significantly higher (P less than 0.005) than normal-virgin mice. Both nonirradiated and day-4 irradiated SPLX-maternal marrow Ep-independent and Ep-dependent CFUE were higher than the nonirradiated and day-4 irradiated SPLX-virgin values (respectively, for each TBI dose studied). On the other hand, nonirradiated and day-4 irradiated SPLX-maternal GM-CFC were lower than the nonirradiated and day-4 irradiated SPLX-virgin GM-CFC values. The data demonstrate the potential of the SPLX-maternal femoral marrow to respond to the stress of low-dose TBI with effective compensatory erythropoiesis, possibly at the expense of granulopoiesis.

Hematopoietic response of splenectomized C3HeB/FeJ and C3H/HeJ mice to lipopolysaccharide.

The paired, inbred mouse strains C3HeB/FeJ and C3H/HeJ differ in their extramedullary hemopoietic response to lipopolysaccharide (LPS). The C3H/HeJ exhibit reduced responses relative to the C3HeB/FeJ in terms of colony-stimulating factor, endogenous and exogenous spleen-derived stem cells (CFUS), and spleen-derived granulocyte-macrophage colony-forming cells (GM-CFC) whereas equivocal responses were noted for the marrow-derived CFUS and GM-CFC. In an effort to determine if the mutational defect was specifically limited to extramedullary expression, we utilized C3HeB/FeJ mice and C3H/HeJ mice at 6 weeks postsplenectomy. The splenectomy emphasizes the medullary response to an i.p. injection of 10 microgram Escherichia coli, LPS-W. Significant differences were revealed in the responses of C3HeB/FeJ and C3H/HeJ marrow-derived cells. Total cells, CFUS, GM-CFC, and the macrophage colony-forming cell (M-CFC) in the C3HeB/FeJ strain all decreased significantly from their saline-injected control values as well as from their counterpart C3H/HeJ values within 48 h after injection of LPS-W. The decline in C3HeB/FeJ CFUS, GM-CFC, and M-CFC was followed by an overshoot, with subsequent return to control values. The total nucleated cells, CFUs, GM-CFC, and M-CFC derived from the C3H/HeJ marrow were characteristically nonresponsive and never varied significantly from their saline-injected control values over the observation period. These results suggest that the phenotypic effect of the defective gene can extend to all hemopoietic tissue, medullary and extramedullary, that normally respond to the factors released through expression of the LPS locus.