Prognostic Significance of the Microenvironment in Human Papillomavirus Oropharyngeal Carcinoma: A Systematic Review.

OBJECTIVE: The immune microenvironment of HPV-associated (HPV+) oropharyngeal squamous cell carcinomas (OPSCCs) (HPV+OPSCCs) differs from that of HPV-independent oropharyngeal cancers (HPV-independent OPSCCs). The literature on the subject is very abundant, demanding an organized synthesis of this wealth of information to evaluate the hypothesis associating the favorable prognosis of HPV+OPSCC patients with a different immune microenvironment. A systematic review of the literature was conducted regarding the microenvironment of HPV+OPSCCs. DATA SOURCE: MEDLINE/PubMed, Embase, and Cochrane Library databases. REVIEW METHODS: A literature search was performed following PRISMA guidelines (Moher D. PLoS Med. 2009). The PEO (Population, Exposure, and Outcome) framework is detailed as follows: P: patients with oropharyngeal squamous cell carcinomas, E: human papillomavirus (HPV), and O: histological and immunological composition of the tumoral microenvironment (TME). No meta-analysis was performed. RESULTS: From 1,202 studies that were screened, 58 studies were included (n = 6,474 patients; n = 3,581 (55%) HPV+OPSCCs and n = 2,861(45%) HPV-independent OPSCCs). The presence of tumor-infiltrating lymphocytes (TIL), CD3+ in 1,733 patients, CD4+ in 520 patients, and CD8+ (cytotoxic T lymphocytes (CTL)) in 3,104 patients, and high levels of PD-L1 expression in 1,222 patients is strongly correlated with an improved clinical outcome in HPV+OPSCCs. CONCLUSION: This systematic review provides the most comprehensive information on the immune microenvironment of HPV+OPSCCs to date. Tumor-infiltrating lymphocytes and PD-L1 expression are associated with a favorable prognosis. B, CD8+ and resident memory cells densities are higher in HPV+OPSCCs. The importance of myeloid lineages is still a matter of debate and research. LEVEL OF EVIDENCE: NA Laryngoscope, 134:1507-1516, 2024.

Economic Incentives in the Socially Optimal Management of Infectious Disease: When [Formula: see text] is Not Enough.

Does society benefit from encouraging or discouraging private infectious disease-risk mitigation? Private individuals routinely mitigate infectious disease risks through the adoption of a range of precautions, from vaccination to changes in their contact with others. Such precautions have epidemiological consequences. Private disease-risk mitigation generally reduces both peak prevalence of symptomatic infection and the number of people who fall ill. At the same time, however, it can prolong an epidemic. A reduction in prevalence is socially beneficial. Prolongation of an epidemic is not. We find that for a large class of infectious diseases, private risk mitigation is socially suboptimal-either too low or too high. The social optimum requires either more or less private mitigation. Since private mitigation effort depends on the cost of mitigation and the cost of illness, interventions that change either of these costs may be used to alter mitigation decisions. We model the potential for instruments that affect the cost of illness to yield net social benefits. We find that where a disease is not very infectious or the duration of illness is short, it may be socially optimal to promote private mitigation effort by increasing the cost of illness. By contrast, where a disease is highly infectious or long lasting, it may be optimal to discourage private mitigation by reducing the cost of disease. Society would prefer a shorter, more intense, epidemic to a longer, less intense epidemic. There is, however, a region in parameter space where the relationship is more complicated. For moderately infectious diseases with medium infectious periods, the social optimum depends on interactions between prevalence and duration. Basic reproduction numbers are not sufficient to predict the social optimum.

Baculoviruses in populations of western spruce budworm.

Population studies of western spruce budworm, Choristoneura occidentalis, revealed that a baculovirus, ChocNPV, was widespread in outbreak populations over a broad geographical area of British Columbia, Canada although the rate of mortality was usually low (<5%). Elevated levels of ChocNPV-related mortality (≈20%) were found when western spruce budworm populations reached high densities (≈300 larvae per kg of Douglas-fir foliage) and contributed to declines in population densities in these areas. A subsample from budworm collections examined using a multiplex-PCR assay showed ChocNPV was the most prevalent virus but also often occurred in combination with a granulovirus, ChocGV and a cypovirus, CoCPV.

Fetal intervention for severe lower urinary tract obstruction: a multicenter case-control study comparing fetal cystoscopy with vesicoamniotic shunting.

OBJECTIVE: To evaluate the efficacy of fetal intervention using fetal cystoscopy or vesicoamniotic shunting in the treatment of severe lower urinary obstruction (LUTO). METHODS: A cohort of 111 fetuses with severe LUTO attending two centers between January 1990 and August 2013 were included retrospectively. Fetuses were categorized into three groups based on the method of intervention: (1) fetal cystoscopy, (2) vesicoamniotic shunting or (3) no intervention. Multivariate analyses were performed to determine the probability of survival and normal renal function until 6 months of age by comparing fetal cystoscopy and vesicoamniotic shunting to no fetal intervention. RESULTS: Of the 111 fetuses with severe LUTO that were included in the analysis, fetal cystoscopy was performed in 34, vesicoamniotic shunting was performed in 16 and there was no fetal intervention in 61. Gestational age at diagnosis, method of fetal intervention and cause of bladder obstruction were associated with prognosis. In multivariate analysis and after adjustment for potential confounders (considering all causes of LUTO) the overall probability of survival was significantly higher with fetal cystoscopy and vesicoamniotic shunting when compared to no intervention (adjusted relative risk (ARR), 1.86 (95% CI, 1.01-3.42; P = 0.048) and ARR, 1.73 (95% CI, 1.01-3.08; P = 0.04) respectively). A clear trend for normal renal function was present in the fetal cystoscopy group (ARR, 1.73 (95% CI, 0.97-3.08; P = 0.06)) but was not observed in the vesicoamniotic shunt group (ARR, 1.16 (95% CI, 0.86-1.55; P = 0.33)). In cases in which there was a postnatal diagnosis of posterior urethral valves, fetal cystoscopy was effective in improving both the 6-month survival rate and renal function (ARR, 4.10 (95% CI, 1.75-9.62; P < 0.01) and 2.66 (95% CI, 1.25-5.70; P = 0.01) respectively) while vesicoamniotic shunting was associated only with an improvement in the 6-month survival rate (ARR, 3.76 (95% CI, 1.42-9.97; P < 0.01)) with no effect on renal function (ARR, 1.03 (95% CI, 0.49-2.17, P = 0.93)). CONCLUSION: Fetal cystoscopy and vesicoamniotic shunting improve the 6-month survival rate in cases of severe LUTO. However, only fetal cystoscopy may prevent impairment of renal function in fetuses with posterior urethral valves. Our data support the idea of performing a subsequent randomized controlled trial to compare the effectiveness of fetal cystoscopy vs vesicoamniotic shunting for severe fetal LUTO.

[MRI-guided breast microbiospy or macrobiopsy: which is the best option for a small tumor?]. / Micro- ou macrobiopsie mammaire guidée par IRM : quel est le meilleur choix pour une petite tumeur ?

The choice of the optimum therapeutic strategy for breast cancer depends on the histological diagnosis of the sample obtained by biopsy. The microbiopsy is the preferred method as it provides an accurate diagnosis of the histological type as well as the main prognostic factors, whilst being simple, fast and inexepensive. However, some infraclinic breast tumors are not accessible by conventional guidance due to excessive depth inside the breast, their small size or technical inability to image them by mammography or ultrasonography. In those cases, the MRI guidance may help to perform the biopsy. Most MRI biopsies are made by large-core needle that are known to alter the histological structure of the tumor and to disturb the anatomopatholgical analysis (size and surgical margin). Those are very important elements to know before treatment. Our case report details an original technique of MRI microbiopsy of a deep 4mm opacity found on the occasion of a patient's mammography. The operative specimen revealed an invasive ductal carcinoma of 4mm diameter which scored III on the Elston and Ellis scale (oestrogen and progesterone receptors tested negative and HER-2 was over-expressed). It was associated with a high grade in situ ductal carcinoma. No systemic treatment was prescribed due to the small size of the carcinoma. The development of partially or totally amagnetic microbiopsy pistols would help perform microbiopses guided by MRI.

[Breast cancer after Hodgkin disease]. / Cancer du sein après maladie de Hodgkin.

Secondary breast cancer represents 6 to 9% of secondary neoplasia after treatments for Hodgkin Disease (HD). Mostly, they appear 10 years after the end of treatments for HD. The most important risk factors are mantle field irradiation and the young age. The means of screening and treatments are still in discussion. We report a case of bilateral intraductal and invasive carcinoma that occurred 16 years after treatments for HD, developing its particularities in diagnosis and treatment, particularly place of conservative treatments and sentinel lymph node biopsy.

Arenaviruses and hantaviruses: from epidemiology and genomics to antivirals.

The arenaviruses and hantaviruses are segmented genome RNA viruses that are hosted by rodents. Due to their association with rodents, they are globally widespread and can infect humans via direct or indirect routes of transmission, causing considerable human morbidity and mortality. Nevertheless, despite their obvious and emerging importance as pathogens, there are currently no effective antiviral drugs (except ribavirin which proved effective against Lassa virus) with which to treat humans infected by any of these viruses. The EU-funded VIZIER project (Comparative Structural Genomics of Viral Enzymes Involved in Replication) was instigated with an ultimate view of contributing to the development of antiviral therapies for RNA viruses, including the arenaviruses and bunyaviruses. This review highlights some of the major features of the arenaviruses and hantaviruses that have been investigated during recent years. After describing their classification and epidemiology, we review progress in understanding the genomics as well as the structure and function of replicative enzymes achieved under the VIZIER program and the development of new disease control strategies.

High yield synthesis, purification and characterisation of the RNase L activators 5'-triphosphate 2'-5'-oligoadenylates.

Upon viral infection, double-stranded viral RNA is detected very early in the host cell by several cellular 2'-5' oligoadenylate synthetases, which synthesize 2'-5' adenylate oligonucleotides that activate the cellular RNase L, firing an early primary antiviral response through self and non-self RNA cleavage. Transfecting cells with synthetic 2'-5' adenylate oligonucleotides activate RNase L, and thus provide a useful shortcut to study the early steps of cellular and viral commitments into this pathway. Defined 2'-5' adenylate oligonucleotides can be produced in vitro, but their controlled synthesis, purification, and characterisation have not been reported in detail. Here, we report a method suitable to produce large amounts of 2-5As of defined lengths in vitro using porcine OAS1 (pOAS) and human OAS2 (hOAS). We have synthesized a broad spectrum of 2-5As at the milligram scale and report an HPLC-purification and characterisation protocol with quantified yield for 2-5A of various lengths.

Genomics and structure/function studies of Rhabdoviridae proteins involved in replication and transcription.

Some mammalian rhabdoviruses may infect humans, and also infect invertebrates, dogs, and bats, which may act as vectors transmitting viruses among different host species. The VIZIER programme, an EU-funded FP6 program, has characterized viruses that belong to the Vesiculovirus, Ephemerovirus and Lyssavirus genera of the Rhabdoviridae family to perform ground-breaking research on the identification of potential new drug targets against these RNA viruses through comprehensive structural characterization of the replicative machinery. The contribution of VIZIER programme was of several orders. First, it contributed substantially to research aimed at understanding the origin, evolution and diversity of rhabdoviruses. This diversity was then used to obtain further structural information on the proteins involved in replication. Two strategies were used to produce recombinant proteins by expression of both full length or domain constructs in either E. coli or insect cells, using the baculovirus system. In both cases, parallel cloning and expression screening at small-scale of multiple constructs based on different viruses including the addition of fusion tags, was key to the rapid generation of expression data. As a result, some progress has been made in the VIZIER programme towards dissecting the multi-functional L protein into components suitable for structural and functional studies. However, the phosphoprotein polymerase co-factor and the structural matrix protein, which play a number of roles during viral replication and drives viral assembly, have both proved much more amenable to structural biology. Applying the multi-construct/multi-virus approach central to protein production processes in VIZIER has yielded new structural information which may ultimately be exploitable in the derivation of novel ways of intervening in viral replication.

Understanding the alphaviruses: recent research on important emerging pathogens and progress towards their control.

The alphaviruses were amongst the first arboviruses to be isolated, characterized and assigned a taxonomic status. They are globally very widespread, infecting a large variety of terrestrial animals, insects and even fish, and circulate both in the sylvatic and urban/peri-urban environment, causing considerable human morbidity and mortality. Nevertheless, despite their obvious importance as pathogens, there are currently no effective antiviral drugs with which to treat humans or animals infected by any of these viruses. The EU-supported project-VIZIER (Comparative Structural Genomics of Viral Enzymes Involved in Replication, FP6 PROJECT: 2004-511960) was instigated with an ultimate view of contributing to the development of antiviral therapies for RNA viruses, including the alphaviruses [Coutard, B., Gorbalenya, A.E., Snijder, E.J., Leontovich, A.M., Poupon, A., De Lamballerie, X., Charrel, R., Gould, E.A., Gunther, S., Norder, H., Klempa, B., Bourhy, H., Rohayemj, J., L'hermite, E., Nordlund, P., Stuart, D.I., Owens, R.J., Grimes, J.M., Tuckerm, P.A., Bolognesi, M., Mattevi, A., Coll, M., Jones, T.A., Aqvist, J., Unger, T., Hilgenfeld, R., Bricogne, G., Neyts, J., La Colla, P., Puerstinger, G., Gonzalez, J.P., Leroy, E., Cambillau, C., Romette, J.L., Canard, B., 2008. The VIZIER project: preparedness against pathogenic RNA viruses. Antiviral Res. 78, 37-46]. This review highlights some of the major features of alphaviruses that have been investigated during recent years. After describing their classification, epidemiology and evolutionary history and the expanding geographic distribution of Chikungunya virus, we review progress in understanding the structure and function of alphavirus replicative enzymes achieved under the VIZIER programme and the development of new disease control strategies.

Long-term outcome of surgically-treated habitual patellar dislocation in children with coexistent patella alta. Minimum follow-up of 11 years.

We retrospectively reviewed the operative treatment carried out between 1988 and 1994 of eight patients with habitual patellar dislocation. In four the condition was bilateral. All patients had recurrent dislocation with severe functional disability. The surgical technique involved distal advancement of the patella by complete mobilisation of the patellar tendon, lateral release and advancement of vastus medialis obliquus. The long-term results were assessed radiologically, clinically and functionally using the Lysholm knee score, by an independent observer. The mean age at operation was 10.3 years (7 to 14) with a mean follow-up of 13.5 years (11 to 16). One patient required revision. At the latest follow-up, all patellae were stable and knees functional with a mean Lysholm knee score of 98 points (95 to 100). In those aged younger than ten years at operation there was a statistically significant improvement in the sulcus angle at the latest follow-up (Student's t-test, p = 0.001). Two patients developed asymptomatic patella infera as a late complication. This technique offers a satisfactory treatment for the immature patient presenting with habitual patellar dislocation associated with patella alta. If performed early, we believe that remodelling of the shallow trochlea may occur, adding intrinsic patellofemoral stability.

[Results of resection for ductal adenocarcinoma of the pancreatic head]. / Résultats carcinologiques de l'exérèse chirurgicale du cancer glandulaire céphalique du pancréas.

INTRODUCTION: Pancreaticoduodenectomy (PD) is the only curative treatment for adenocarcinoma of the pancreatic head but is associated with a significant early morbidity and a poor long term survival. Therefore, its value is still debated. The aim of this study was to evaluate early and distant results of PD for pancreatic adenocarcinoma, and to identify prognostic factors. SUMMARY: Seventy-nine patients who underwent PD with curative intent for adenocarcinoma of the pancreatic head from 1982 to 2002 were studied retrospectively. The following data were evaluated: operative mortality, long-term survival, prognostic factors (through univariate and multivariate analysis), and characteristics of 5-year survivors. RESULTS: Mortality rate was 1.3%. Survival at 1, 3 and 5 years was 46%, 26% and 11%. The median survival was 12 months. The prognostic factors were the T stage (T.N.M. classification) and radicality of resection. After multivariate analysis, radicality of resection was the only independent prognostic factor. Five patients survived for more than 5 years. They did not differ of the other patients but none had positive margin or venous invasion. CONCLUSIONS: These results (low mortality, significant distant survival including some long term survivors) suggest that PD for pancreatic adenocarcinoma must be indicated in most low-risk patients. PD remains the only curative treatment allowing prolonged survival.

Solvent dependence of the structure and magnetic ordering of ferrimagnetic manganese(III) meso-tetraphenylporphyrin tetracyanoethenide, [MnTPP]+[TCNE]*-.

Tetraphenylporphinatomanganate(III) tetracyanoethenide, [MnTPP][TCNE], is the prototype of a growing family of linear chain (1-D) coordination polymers that magnetically order as ferrimagnets. [MnTPP][TCNE].xS [S = PhMe (x = 2), 1,2-C(6)H(4)Me(2) (x = 1), 1,2-C(6)H(4)Cl(2) (x = 3), 1,2,4-C(6)H(3)Cl(3) (x = 2), and 1,3-C(6)H(4)Cl(2) (x = 2)] have been prepared and structurally and magnetically characterized. All form 1-D chain structures with intrachain Mn.Mn separations ranging from 9.202 to 10.218 A. The 173 K crystal structure of [MnTPP][TCNE].2PhMe has been rerefined, revealing that the [TCNE](*)(-) is 2-fold-disordered and coordinated to Mn(III) by a pair of trans cyano nitrogen atoms to form parallel one-dimensional chains. The two orientations of [TCNE](*)(-) are related by a 180 degrees rotation about the diagonal axis joining the trans nitrogen atoms bound to Mn(III). The major form has an occupancy of 83.3(4)% with a Mn-N(TCNE) distance of 2.328(3) A and a MnNC angle of 146.8(8) degrees. The minor form, with 16.7(4)% occupancy, has a Mn-N(TCNE) distance of 2.176(15) A and a MnNC angle of 152.3(39) degrees. Lattice packing and molecular bonding imply static as opposed to dynamic disorder. The magnetic properties depend on the type and quantity of the solvent present in the structure. Desolvation via heating in n-octane (127 degrees C), n-dodecane (216 degrees C), and/or vacuum thermolysis (175 degrees C) leads to numerous different desolvated materials with differing magnetic properties. At higher temperatures the magnetic susceptibility can be fit by the Curie-Weiss expression, chi varies with (T - theta)(-1), with theta = 44, 52, 72, 55, and 77 K for the toluene, 1,2-xylene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, and 1,2,4-trichlorobenzene solvates, respectively. The T(c)'s were taken as the maximum in 10 Hz chi'(T) and are 7.8, 9.2, 11.3, 10.8, and 8.2 K for the PhMe, 1,2-xylene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, and 1,2,4-trichlorobenzene solvates, respectively. Upon desolvation the T(c)'s increase for the PhMe, 1,2-xylene, 1,2,4-trichlorobenzene solvates and decrease for the 1,2- and 1,3-dichlorobenezene solvates. The compounds show one-dimensional ferrimagnetic exchange behavior at high temperatures with intrachain exchange of J/k(b) = -63, -99, -234, -100, and -200 K for toluene, 1,2-xylene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, and 1,2,4-trichlorobenzene solvates, respectively, as determined from fits to the Seiden expression, which models isolated 1-D interactions among alternating S = 2 classical and S = (1)/(2) quantum spins. For variation in the temperature at which the peak occurs per decade of frequency, phi, (DeltaT(f)/T(f))/Delta(log omega) is 0.167, 0.168, 0.066, 0.171, and 0.024 for toluene, 1,2-xylene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, and 1,2,4-trichlorobenzene, respectively, typical of spin glass behavior. Since [TCNE](*)(-) is only disordered for the PhMe solvate and all five solvates exhibit spin glass behavior, the spin glass behavior cannot be attributed to this disorder.

Heterodimerization between the glucocorticoid receptor and the unrelated DNA-binding protein, Xenopus glucocorticoid receptor accessory factor.

The adrenal steroid hormones, glucocorticoids, control many physiological responses to trauma, including elevated synthesis of fibrinogen, a major blood-clotting protein. Glucocorticoid regulation of the gamma-fibrinogen subunit gene in Xenopus laevis is mediated by a binding site for Xenopus glucocorticoid receptor accessory factor (XGRAF) and a contiguous glucocorticoid response element (GRE) half-site. Here, we characterize the protein:DNA complex formed by a cooperative interaction between XGRAF, GR, and the DNA. We demonstrate that the complex contains XGRAF by competition in a gel shift assay. The presence of GR is established by two criteria: 1) size dependence of the XGRAF:GR:DNA complex on the size of the GR component and 2) interference with complex formation by GR antibody. Cooperative binding of XGRAF and GR to the DNA was quantitated, showing that GR favors binding to XGRAF:DNA compared with free DNA by a factor of 30. The cooperative interaction between XGRAF and GR can occur on nicked DNA but is disrupted when 1 bp is inserted between the XGRAF binding site and half-GRE. Significantly, this loss of physical association in vitro correlates with loss of XGRAF amplification of GR activity in transiently transfected primary Xenopus hepatocytes. The simplest explanation for cooperativity between XGRAF and GR is formation of a DNA-bound heterodimer of these two proteins. This mechanism represents a new mode of transcriptional regulation in which GR and a nonreceptor protein form a heterodimer, with both partners contacting their specific DNA sites simultaneously.

[Late intestinal fistula following implantation of parietal abdominal prostheses]. / Fistules intestinales tardives après implantation de prothèse pariétale abdominale.

STUDY AIM: The aim of this retrospective study was to describe an unusual complication of the nonabsorbable meshes used for repair of incisional hernia or inguinal hernia. PATIENTS AND METHODS: This study included eight observations of intestinal fistulas that occurred between 1 and 13 years after using Mersilène (Dacron) mesh for repair of an incisional hernia (7 cases) and an inguinal hernia (1 case). There were 6 men and 2 women (mean age: 58 years, range: 35-85 years) with an external intestinal fistula (n = 6) or an internal intestinal fistula (n = 2). All the patients required a reoperation for extraction of the mesh and treatment of the bowel injuries. RESULTS: There was one secondary death in a 85 years old woman in relation with a vascular complication after incomplete excision of the prosthesis. In five patients out of six, there was a recurrence of the incisional hernia. CONCLUSION: The intestinal fistulas associated with prosthetic repair of the abdominal wall are mostly observed with intraperitoneal mesh but this factor is not exclusive. Their frequency after repair of incisional or inguinal hernia with non absorbable mesh is estimated between 0.3 and 3.5%. The use of nonabsorbable mesh should be limited to the indications of strict necessity, without any septic context or emergency surgery. The contact of the mesh with the bowel should be formally avoided.

[Costal chondroma and chondrosarcoma]. / Chondromes et chondrosarcomes costaux.

The aim of this study was to report two cases of chondrosarcoma located on the chest wall, in order to emphasize the difficulty encountered by the pathologist to differentiate a chondrosarcoma from a chondroma and the importance, in our opinion, of performing a large resection with wide margins in all cases.

Adolescent cocaine and injection stress effects on the estrous cycle.

Chronic cocaine exposure during critical periods of development induces short- and long-term effects. During the pubertal period, the hypothalamic-pituitary-gonadal (HPG) axis undergoes many dynamic changes. The present study investigated whether chronic periadolescent cocaine alters reproductive maturity in the rat. Sixty female Long-Evans hooded rats were randomly assigned to one of three conditions (20 mg cocaine/kg/day, saline injected and uninjected), for dosing from postnatal day 21 (P21) through P60. Several indicators of reproductive maturation and functioning were assessed during and following treatment. Cocaine exposure had no effect on the onset of puberty or on the date of first ovulation. The number of proestrus-estrus transitions was significantly lower in cocaine-exposed females compared to uninjected females, but not compared to saline-injected controls. This reduction was observed during exposure to cocaine, as well as after the cessation of injections. During the dosing period, cocaine-exposed rats also exhibited a greater number of cycles that had no clear P-E transition than did UN subjects; this effect disappeared once injections stopped. These alterations suggest immediate, and possibly persisting, alterations in the control of ovulation after chronic cocaine exposure throughout adolescence. Interestingly, during the injection period, the saline-injected females had a significantly greater number of diestrus days compared to uninjected and cocaine-injected animals, as well as a lower proportion of regular 4- and 5-day cycles. These differences disappeared once injections stopped. These results suggest a stress-induced irregularity of the estrous cycle, possibly attenuated by cocaine and recoverable after exposure. The present findings indicate that the HPG axis is susceptible to short-term, and possibly to long-term, alterations induced by cocaine exposure throughout the adolescent period.

The binding site for Xenopus glucocorticoid receptor accessory factor and a single adjacent half-GRE form an independent glucocorticoid response unit.

In Xenopus laevis, transcription of the gamma-fibrinogen subunit gene is activated by glucocorticoids. Hormone induction is regulated by three glucocorticoid response element (GRE) half-sites and an additional DNA sequence which binds a novel hepatocyte nuclear protein, Xenopus glucocorticoid receptor accessory factor (XGRAF). The XGRAF binding site (GAGTTAA) is located directly upstream of the most distal half-GRE. The proximity of the binding sites for XGRAF and the glucocorticoid receptor (GR) led to the hypothesis that these two sites form a glucocorticoid response unit (GRU). By transfecting DNA into primary hepatocytes, we showed that this GRU confers hormone responsiveness in the absence of other half-GREs. The XGRAF binding site enhances function of the half-GRE without itself responding to glucocorticoids. The GRU retains efficacy in other locations relative to the gamma-fibrinogen gene promoter, further increases transcription when present in multiple copies, and activates a heterologous promoter. Despite the contiguity of the XGRAF binding site and half-GRE, the two sites can be occupied simultaneously in vitro. The binding characteristics correlate with function since mutations that disrupt concurrent XGRAF and GR binding also impair transcription. This novel GRU represents a new regulatory mechanism that may be applicable to other glucocorticoid responsive genes that lack a full GRE.