Cardiac Axis in Early Gestation and Congenital Heart Disease

Congenital heart defects represent the most common structural anomalies observed in the fetal population, and they are often associated with significant morbidity and mortality. The fetal cardiac axis, which indicates the orientation of the heart in relation to the chest wall, is formed by the angle between the anteroposterior axis of the chest and the interventricular septum of the heart. Studies conducted during the first trimester have demonstrated promising outcomes with respect to the applicability of cardiac axis measurement in fetuses with congenital heart defects as well as fetuses with extracardiac and chromosomal anomalies, which may result in improved health outcomes and reduced healthcare costs. The main aim of this review article was to highlight the cardiac axis as a reliable and powerful marker for the detection of congenital heart defects during early gestation, including defects that would otherwise remain undetectable through the conventional four-chamber view.

Dramatic mechanistic switch in Sn/AuI group exchanges: transmetalation vs. oxidative addition

The mechanism of Ph/X exchange in reactions involving SnPhⁿBu₃ and [AuXL] complexes switches dramatically from the usual concerted mechanism involving Ar/X mixed bridges when X = Cl, to an unexpected oxidative addition/reductive elimination pathway via an Au^III intermediate when X = vinyl.

Acitretin suppression of squamous cell carcinoma: Case report and literature review

Retinoids have been used for the treatment and suppression of cutaneous malignancies in patients with basal cell nevus syndrome, xeroderma pigmentosum, and in patients with recurrent skin cancers as a result of immunosuppression for renal transplantation. We report a 40-year-old male who began to develop multiple squamous cell carcinomas of the skin after treatment with PUVA for severe psoriasis. The numbers of squamous cell carcinomas increased when acitretin was discontinued and decreased when he was taking the drug at a dose of 25 mg daily. Acitretin should be considered as a maintenance therapy for psoriasis patients developing squamous cell carcinomas as a result of PUVA therapy.

Genetic similarity of hepatitis C virus and fibrosis progression in chronic and recurrent infection after liver transplantation

The effect of hepatitis C virus (HCV) genetic heterogeneity on clinical features of post-transplantation hepatitis C is controversial. Different regions of the HCV genome have been associated with apoptosis, fibrosis, and other pathways leading to liver damage in chronic HCV infection. Besides, differences in immunodominant regions, such as NS3, may influence HCV-specific immune responses and disease outcome. In the liver transplant setting, a recent study has reported a positive association between HCV-1b Core region genetic relatedness 5-year post-transplantation and histological severity of recurrent hepatitis C. We have compared nucleotide sequences of HCV Core, NS3 and NS5b regions in HCV-1b-infected patients 3 years post-transplantation (n = 22). A cohort of nontransplanted patients (n = 22) was used as control of natural chronic HCV-1b infection. Histological evaluation was used to define the rate of fibrosis progression. Molecular variance analysis did not show significant differences in HCV sequences between transplanted and nontransplanted patients, or between those with fast or slow fibrosis progression. The same results were obtained when analysing phylogenetic trees for Core, NS3 and NS5b regions. A more appropriate clustering method (using minimum spanning networks) revealed a significant positive relationship between HCV genetic similarity in Core (r = 0.550, P < 0.01) and NS5b regions (r = 0.847, P < 0.01) and the yearly rate of fibrosis progression in nontransplanted patients which, in contrast, was not observed in transplanted patients. Our results indicate that some strains of HCV-1b might be more pathogenic in the natural course of chronic infection by this virus subtype. In the liver transplant setting, when the immune response is severely compromised, other mechanisms are probably more important in determining hepatitis C progression.

Prophylactic and therapeutic vaccines for genital papillomavirus infection

The development of potential therapeutic and prophylactic vaccines for human papillomavirus (HPV) infection is a very exciting area of HPV research. There are a number of features of HPV biology that makes the development of a vaccine particularly difficult, although there are several examples of vaccines that have had spectacular success in the prevention of other viral diseases. Our poor understanding of the immune response to HPV infection is the first problem. We do not understand the mechanism by which spontaneous clearing of warts is generated and therefore cannot particularly target this pathway in the development of a vaccine. Furthermore, there is no in vitro culture system nor an animal model for HPV. Another problem is that there is no ready source of live virus that might be exploited for a live attenuated viral vaccine, such as was used with poliovirus. Although most other viruses spend a portion of their life cycle in the systemic circulation where they are vulnerable to neutralizing antibodies, HPV remain exclusively in the epithelium and thus antibodies must transverse the basement membrane and reach the other layers of the skin or mucosa to be effective in preventing infection. Significant progress is being made in the development of potential vaccine candidates despite these and other confounding factors.

Molecular diagnosis of skin-associated infectious agents

Molecular pathology is a relatively new division of laboratory medicine that detects, characterizes, and/or quantifies nucleic acids to assist in the diagnosis of human disease. Molecular assays augment classic areas of laboratory medicine by providing additional diagnostic data more quickly or by providing results that are not obtainable using standard methods. For these reasons, molecular pathology is the most rapidly growing area in laboratory medicine.

Loss of p16Ink4a with retention of p19Arf predisposes mice to tumorigenesis

The cyclin-dependent kinase inhibitor p16INK4a can induce senescence of human cells, and its loss by deletion, mutation or epigenetic silencing is among the most frequently observed molecular lesions in human cancer. Overlapping reading frames in the INK4A/ARF gene encode p16INK4a and a distinct tumour-suppressor protein, p19ARF (ref. 3). Here we describe the generation and characterization of a p16Ink4a-specific knockout mouse that retains normal p19Arf function. Mice lacking p16Ink4a were born with the expected mendelian distribution and exhibited normal development except for thymic hyperplasia. T cells deficient in p16Ink4a exhibited enhanced mitogenic responsiveness, consistent with the established role of p16Ink4a in constraining cellular proliferation. In contrast to mouse embryo fibroblasts (MEFs) deficient in p19Arf (ref. 4), p16Ink4a-null MEFs possessed normal growth characteristics and remained susceptible to Ras-induced senescence. Compared with wild-type MEFs, p16Ink4a-null MEFs exhibited an increased rate of immortalization, although this rate was less than that observed previously for cells null for Ink4a/Arf, p19Arf or p53 (refs 4, 5). Furthermore, p16Ink4a deficiency was associated with an increased incidence of spontaneous and carcinogen-induced cancers. These data establish that p16Ink4a, along with p19Arf, functions as a tumour suppressor in mice.

Reduction of postherpetic neuralgia in herpes zoster

BACKGROUND

Persons 50 years of age and older are not only at increased risk of developing herpes zoster, they are also more likely to suffer the long-term morbidity of postherpetic neuralgia (PHN). PHN is pain persisting after the rash of herpes zoster has healed. PHN affects at least 40% of all herpes zoster patients over age 50 and over 75% of herpes zoster patients over age 75; PHN is the single most common neurologic condition in elderly patients.

OBJECTIVE

The objective of this review is to evaluate interventions that may reduce or even eliminate PHN. No single therapy has been consistently effective for PHN. The most effective approach appears to be with the use of antiviral therapy early in the course of herpes zoster. The goals of ongoing studies in herpes zoster are to develop interventions that will further reduce the symptoms of PHN and/or to eliminate PHN by prophylaxis using the varicella vaccine.

CONCLUSIONS

Reduction of PHN can best be achieved with the use of antiviral medication early in the course of herpes zoster; other classes of drugs are minimally effective in treating established PHN. Widespread use of the varicella vaccine may lead to secondary reductions in PHN in the distant future.

Are posttransplantation protocol liver biopsies useful in the long term?

Controversy exists about the usefulness of yearly protocol liver biopsies after liver transplantation, mainly among patients with normal transaminase levels. The aim of this study is to determine (1) the prevalence and cause of histological liver injury in transplant recipients with a minimum histological follow-up of 1 year (n = 254), and (2) the correlation between histological findings and transaminase values. The main indication for liver transplantation was viral-related cirrhosis (61%; 86% caused by hepatitis C virus [HCV]). Protocol liver biopsies were performed yearly for the first 5 years in HCV-infected transplant recipients and at 1 and 5 years in the remaining patients. Histological liver injury included several categories of liver damage (hepatitis, rejection, steatohepatitis, cholangitis, and Budd-Chiari-like lesions). Among biopsy specimens categorized as hepatitis, severe hepatitis was defined as the presence of stage 3 or greater fibrosis. The prevalence of liver injury increased significantly with time (42% v 56% at 1 and 5 years, respectively; P =.09) and was significantly greater in patients who underwent transplantation for HCV-related cirrhosis than in those who underwent transplantation for other reasons (P =.0001). The most frequent category of liver injury was hepatitis (97% and 96% at 1 and 5 years, respectively). Although a proportion of patients with liver injury (12% to 29%) had normal transaminase values, this percentage was almost null in patients with severe hepatitis. Normal histological characteristics were found in the vast majority of non-HCV-infected transplant recipients with normal transaminase values. Given the high prevalence of abnormal histological findings, particularly the increase over time of those defined as severe, protocol liver biopsies are clearly justified in HCV-infected transplant recipients. Conversely, given the rarity of abnormal histological findings, protocol liver biopsies should be questioned in non-HCV-infected transplant recipients with normal transaminase values.

Human papillomavirus, smoking, and cancer

BACKGROUND

The effect of smoking on human papillomavirus (HPV) activity and subsequent dysplasia and neoplasia remains controversial.

OBJECTIVE

To determine any reported effects of smoking on either HPV activity or HPV-related dysplasia/cancer using retrospective analysis of the literature from 1966 through 1998 via Toxline and PubMed to search for "smoking," "papillomavirus," and "cancer."

CONCLUSION

Several recent large studies demonstrated that smoking was associated with a greater incidence of cervical, vulvar, penile, anal, oral, and head and neck cancer in a dose-dependent fashion, while other studies did not show any correlation between smoking and cervical dysplasia after multivariate adjustment. Recent studies have also indicated that smoking may be more closely related to high-grade lesions of the cervix and vulva. These data provide evidence of an association between HPV, smoking, and cancer. Progression of dysplasia likewise seems to be associated with smoking. Several groups have attempted to discern whether the connection between smoking and cervical cancer is from local immunosuppression and/or from direct carcinogenic effects.

Tobacco use and skin disease

BACKGROUND

The primary objective of this review is to evaluate the mucocutaneous manifestations of tobacco use.

METHODS

Computerized literature searches were conducted for English language articles related to skin/mucous membrane disease and use of tobacco. The primary criterion for assessing data quality and validity was the demonstration of a causal relationship between tobacco use and skin/mucous membrane disease.

RESULTS

This review of the literature shows that a number of disorders and diseases of the skin and mucous membranes are related to tobacco use.

CONCLUSIONS

Since millions of persons use tobacco despite its well publicized relationship to increased mortality, knowledge of the mucocutaneous morbidity associated with tobacco use may help physicians in counseling their patients.

Famciclovir treatment in transplant recipients with HBV-related liver disease: disappointing results

OBJECTIVE

Long-term administration of hepatitis B immune globulin is effective as prophylaxis for hepatitis B virus (HBV) reinfection but is limited by cost, side effects, availability and a failure rate of 20%. Famciclovir has been shown to be effective in the treatment of hepatitis B in the immunocompetent patient. Fewer data exist in the liver transplant setting, particularly regarding its efficacy in de novo HBV infection. The aims of this pilot study were to determine the effectiveness and safety of long-term administration of famciclovir in recurrent (n = 3) and de novo (n = 3) HBV infection after liver transplantation.

METHODS

Six patients with postransplant HBV infection (positivity of serum HBsAg and HBV DNA), four of whom were HBeAg positive, were treated with famciclovir (500 mg, 3 times a day) with a minimum follow-up period of 12 months. Biochemical, serological, virological (HBV DNA by hybridization assays and polymerase chain reaction), and histological (including HBV immunostaining) endpoints were evaluated.

RESULTS

None of the patients had a complete biochemical response, with a near complete normalization of ALT levels being observed in 3/6 patients. There was a lack of correlation between virological and biochemical responses. None of the patients seroconverted to anti-HBs or anti-HBe. A virological clearance was observed in only two patients, whereas a moderate reduction in HBV DNA levels was present in one. HBV DNA levels were higher than levels during pretreatment in the three remaining patients. Histological improvement was only observed in one patient.

CONCLUSION

Famciclovir alone appears of limited efficacy in the treatment of HBV infection after liver transplantation.

De novo hepatitis B after liver transplantation from hepatitis B core antibody-positive donors in an area with high prevalence of anti-HBc positivity in the donor population

Transmission of hepatitis B virus (HBV) infection from donors who are negative for hepatitis B surface antigen (HBsAg-) but positive for antibody to hepatitis B core antigen (anti-HBc+) has been reported. However, previous studies were generally performed in geographic regions with a low prevalence of anti-HBc positivity in the liver donor population. The aims of this study are (1) to assess the risk for de novo hepatitis B in recipients of livers from anti-HBc+ donors in an area of high prevalence of anti-HBc positivity in the donor population, and (2) to analyze the risk factors for acquisition of HBV infection from anti-HBc+ donors. The transplantation experience of a single center between 1995 and 1998 was reviewed. Thirty-three of 268 liver donors (12%) were HBsAg- and anti-HBc+ during the study period. The proportion of anti-HBc+ donors increased with age; it was lowest (3.6%) in donors aged 1 to 20 years and highest (27.1%) in donors aged older than 60 years. Of the 211 HBsAg- recipients with 3 months or more of HBV serological follow-up, 30 received a liver from an anti-HBc+ donor and 181 received a liver from an anti-HBc- donor. Hepatitis B developed in 15 of 30 recipients (50%) of livers from anti-HBc+ donors but in only 3 of 181 recipients (1.7%) of livers from anti-HBc- donors (P < .0001). None of the 4 recipients who were antibody to HBsAg (anti-HBs)+ at the time of transplantation developed HBV infection after receiving a liver from an anti-HBc+ donor compared with 15 of 26 recipients (58%) who were anti-HBs- (P =.10). None of the 5 anti-HBc+ recipients developed hepatitis B compared with 15 of 25 anti-HBc- recipients (60%; P = 0.04). Child-Pugh score was significantly higher in recipients of livers from anti-HBc+ donors who developed HBV infection than in those who did not (9 +/- 2 v 7 +/- 1; P =.03). In our area, testing liver donors for anti-HBc is mandatory, particularly in older donors. With such information available, anti-HBc+ donors can be safely directed to appropriate recipients, mainly those with anti-HBs and/or anti-HBc at the time of transplantation. In the current era of donor shortage, this policy would allow adequate use of such donors.

Natural history of clinically compensated hepatitis C virus-related graft cirrhosis after liver transplantation

The natural history of clinically compensated hepatitis C virus (HCV) cirrhosis after liver transplantation is unknown. This information is relevant to transplant centers to improve the management of these patients and decide the optimal timing for retransplantation. The aims of the study were (1) to describe the natural history of patients with HCV-cirrhosis transplants in a center with annual liver biopsies, and (2) to determine predictors for clinical decompensation, retransplantation, and mortality rates. A total of 49 patients with HCV-graft cirrhosis, 39 clinically compensated at histologic diagnosis of cirrhosis (post-liver transplantation cirrhosis) were included and followed up for 1 year (15 days-3.5 years). All patients tested were infected with genotype 1b. Predictive variables included histologic activity index (HAI) at post-liver transplantation cirrhosis, liver function tests, age, sex, and maintenance immunosuppression. Eighteen of 39 patients developed at least 1 episode of decompensation after a median of 7.8 months (4 days-2.6 years; 93% ascites). The cumulative probability of decompensation was 8%, 17%, and 42% at 1, 6, and 12 months, respectively. Graft and patient survival rates were 100%, 85%, and 71% and 100%, 92%, and 74% at 1, 6, and 12 months, respectively. Patient survival rates dropped significantly once decompensation developed (93%, 61%, and 41% at 1, 6, and 12 months, respectively). Variables associated with decompensation, retransplantation, and mortality rate included a high Child-Pugh score (>A), low levels of albumin at post-liver transplantation cirrhosis, and a short interval between liver transplantation and post-liver transplantation cirrhosis. The natural history of clinically compensated HCV-graft cirrhosis is shortened when compared with immunocompetent patients. If retransplantation is considered, it should be performed promptly once decompensation develops.

An overview of sexually transmitted diseases. Part III. Sexually transmitted diseases in HIV-infected patients

The HIV epidemic has dramatically altered the field of sexually transmitted diseases (STDs). HIV infection is unique among sexually transmitted diseases because it can modify the clinical presentation and features of other STDs. Conversely, other STDs can affect the transmission of HIV. This review is the third part of a series that has provided a general overview of STDs. In this article, genital ulcer diseases (genital herpes, syphilis, chancroid, lymphogranuloma venereum, and granuloma inguinale), human papillomavirus infection (anogenital warts and subclinical infections), molluscum contagiosum, human herpesvirus 8 infection, viral hepatitis, and ectoparasitic infestations (scabies and pediculosis pubis) are discussed as they occur in HIV-infected hosts. Additional features as they relate to HIV-infected patients, such as epidemiology and transmission, are discussed when applicable.

LEARNING OBJECTIVE

At the conclusion of this learning activity, participants should improve their understanding of sexually transmitted diseases in the HIV-infected host.

Macrodactyly: report of eight cases and review of the literature

Congenital enlargement of one or several digits of the hands or feet (macrodactyly) is a rare disorder. A considerable proportion of the patients with this condition are referred to dermatology departments. The majority of the cases reported in the literature represent hamartomas with combined hypertrophy of several, predominantly lipomatous, soft tissue components and overgrowth of bone. The differential diagnosis includes Klippel-Trenaunay-Weber syndrome, neurofibromatosis, Milroy disease, and Proteus syndrome. We describe eight cases of congenital macrodactyly, discuss the findings, and propose a simple clinicopathologic terminology.

High incidence of allograft cirrhosis in hepatitis C virus genotype 1b infection following transplantation: relationship with rejection episodes

The natural history of hepatitis C virus (HCV) infection following liver transplantation and predictors of disease severity remain controversial. The aims of the study were to assess in a homogeneous population of 81 cyclosporine-based HCV-infected liver transplant recipients mostly infected with genotype 1b and undergoing strict protocol annual biopsies: 1) the histological progression of posttransplantation HCV disease and, in particular, the incidence of HCV-related graft cirrhosis within the first 5 years after surgery; and 2) the relationship between progression to cirrhosis and i) rejection episodes and ii) first-year liver biopsy findings. We studied 81 consecutive HCV-RNA-positive patients (96% genotype 1b) undergoing liver transplantation between 1991 and 1996 with a minimum histological follow-up of 1 year. All patients received cyclosporine-based immunosuppression and underwent protocol yearly liver biopsies for the first 5 years. The mean histological follow-up was 32 months (range, 12-60 months). Biopsies were scored according to the histological activity index (HAI), with separate evaluation of grade (activity) and stage (fibrosis). Histological hepatitis, present in 97% of patients in the most recent biopsy, was moderate or severe in 64%. Twelve patients developed HCV-related cirrhosis at a median time of 24 months (range, 12-48 months), with an actuarial rate of HCV-cirrhosis of 3.7%, 8.5%, 16%, 28%, and 28% at 1, 2, 3, 4, and 5 years, respectively. Rejection was significantly more common among patients with cirrhosis versus those without (83% vs. 48%; P =.02), with an association between the incidence of cirrhosis and the number of rejection episodes: 5%, 15%, and 50% in patients without rejection, one and two episodes, respectively (P =.001). The degree of activity and fibrosis score in the first-year biopsy were higher in patients who developed cirrhosis than in those who did not (P =.008 and.18, respectively). In conclusion, HCV genotype 1b-infected liver recipients are at a high risk of developing graft cirrhosis in the first 4 to 5 years following transplantation, especially those with previous rejection episodes. First-year liver biopsies may help to sooner identify patients at the highest risk, improving further patient management.

Antigen-induced eosinophilic lung inflammation develops in mice deficient in chemokine eotaxin

The mechanisms that regulate the selective infiltration of eosinophils in certain allergic diseases are still poorly understood. The CC chemokine eotaxin is a potent chemoattractant, highly specific for eosinophils. Recent studies have implicated that eotaxin plays an important role in the recruitment of eosinophils in different inflammation processes. A number of other chemokines, cytokines, and chemoattractants also have chemotactic activities for eosinophils and some of them present high selectivity for eosinophils. To further study the role of eotaxin in inflammation, we generated mutant mice with the eotaxin gene disrupted and replaced by the Escherichia coli beta-galactosidase gene. These mice developed normally and had no histologic or hematopoietic abnormalities. Furthermore, our studies showed that the lack of eotaxin did not affect the recruitment of eosinophils in the inflammation models induced by Sephadex beads and thioglycollate, as well as in an experimental lung eosinophilia model induced by ovalbumin aerosol challenge, even at the onset of the inflammatory response. The replacement of the eotaxin gene by the beta-galactosidase gene provided a useful marker to monitor the activity of the eotaxin promoter under normal conditions and after antigen challenges. Immunohistochemical staining suggested that endothelial cells were the major sources of eotaxin expression.

[Incidence of de novo neoplasms after liver transplantation]

BACKGROUND

De novo malignancy developing after transplantation constitutes a well-known complication or organ transplantation, mainly described among renal recipients.

AIM

To determine the incidence of de novo internal malignancies (excluding therefore skin cancers and recurrent hepatocellular carcinoma) in a cohort of 183 patients undergoing liver transplantation (OLT) between 6/1/1991 and 12/1/1996 with a minimum follow-up of 12 months and under cyclosporine-azathioprine-prednisone.

PATIENTS AND METHODS

The study comprised 183 patients (mean age: 53 [8] years, with 70% males) whose charts were reviewed retrospectively. Rejection, steroids treatment, methyl-prednisolone bolus and OKT3 use were compared in the cases and in the matched control group.

RESULTS

Seven malignancies were detected: 3 lung carcinomas, 1 larynx, 1 prostate, 1 colon and 1 ovarian. The mean age was 53 (8) years. The diagnosis of cancer was made at an average time of 24 (17) months (range, 10-54) post-OLT. Three patients died with a mean survival of 31 (16) months. OLT indication was mainly for viral liver disease (5/7). Although not statistically significant, immunosuppression data were higher among patients with cancer than in the matched group. Two additional patients developed post-transplantation lymphoproliferative diseases at 2 and 9 months, respectively.

CONCLUSION

We observed a wide variety of malignancies after OLT, but no associated factor was found, even though there was a trend to higher doses of immunosuppression in patients with cancers. The institution of preventive measures and surveillance programs may allow for early institution of therapy, improving therefore the survival.

Early development of chronic active hepatitis in recurrent hepatitis C virus infection after liver transplantation: association with treatment of rejection

BACKGROUND/AIMS

We retrospectively studied 63 consecutive patients (mean age 54+/-8) with hepatitis C virus genotype 1b recurrence after liver transplantation and with a minimum histological follow-up of 1 year, in order to determine whether an early severe recurrence, defined as the development of chronic active hepatitis within the first 2 years post-liver transplantation, was associated with increased immunosuppression.

METHODS

The 1st year immunosuppression data (rejection episodes, boluses of methyl-prednisolone, cumulative doses of prednisone and azathioprine, OKT3 use) were recorded, and evaluated as predictive of severe recurrence at 1 and 2 years post-liver transplantation. Chronic active hepatitis and rejection were defined by histological criteria. Immunosuppression consisted of cyclosporine, azathioprine and prednisone. The treatment of rejection was based on a "bolus" of 1 g methyl-prednisolone/3 days.

RESULTS

At 1 year, 64% (40/63) of the patients had chronic active hepatitis, whereas of the 40 patients who had a 2nd year biopsy available, 75% had chronic active hepatitis at 2 years. At 1 year post-liver transplantation, no significant association was observed between immunosuppression and the development of chronic active hepatitis. In contrast, at 2 years, rejection (p=0.006), treatment of rejection (p=0.05), methyl-prednisolone boluses (p=0.013) and the number of rejection episodes (p=0.0034) occurring during the 1st year post-liver transplantation were significantly more common in patients with chronic active hepatitis. There was also a trend towards higher cumulative steroids (9447+/-3176.5 vs 7891.5+/-2111 mg) and higher cumulative azathioprine doses (13472+/-11154 vs 6233.5+/-5937 mg) in patients with chronic active hepatitis as compared to those who did not develop chronic active hepatitis.

CONCLUSIONS

Rejection and/or its treatment may accelerate the natural history of hepatitis C virus genotype 1b infection post-liver transplantation.

Characterization of local memory cells in stage-classified pulmonary tuberculosis: preliminary observations

Immunophenotype analysis and proliferative responses were investigated in bronchoalveolar lavage (BAL) cells from 21 patients with stage-classified tuberculosis: six with localized pulmonary infiltrate (LPI); seven with diffuse pulmonary infiltrate (DPI); and eight with pleural effusions (PE). Bronchoalveolar lavage cells from these patients contained a high number of cells/ml. The macrophage number was significantly lower in the DPI group (P < 0.05) compared to the LPI or PE groups. Conversely, neutrophils were markedly increased in DPI patients compared to LPI (P < 0.01) and PE (P < 0.01) patients. Lymphocyte infiltration (97.7 +/- 2.3% CD3+, > 83% alphabeta+ and CD4+ > CD8+) was observed in the three groups. A significant increase in the number of total lymphocytes (P < 0.01) and CD4+ cells (P < 0.05) was observed in the LPI group compared to the PE group. In the LPI group CD4+CD45RO+ cell infiltration was higher than CD4+CD45RA+ cells (P < 0.001), contrasting to similar numbers of these subpopulations in the DPI group. Lymphocytes from three out of three LPI patients (alphabeta+CD4+CD45RO+) responded against tuberculin purified protein derivative contrasting to the unresponsiveness of five patients with either DPI or PE. This impaired response was reverted in two out of five patients by using peripheral blood monocytes instead of alveolar macrophages. It is suggested that, in humans, alphabetaCD4+CD45RO cells are the main lymphocyte type involved in the initial local cell-mediated immune response against Mycobacterium tuberculosis.

Multiple hemopoietic defects and lymphoid hyperplasia in mice lacking the transcriptional activation domain of the c-Rel protein

The c-rel protooncogene encodes a member of the Rel/nuclear factor (NF)-kappaB family of transcriptional factors. To assess the role of the transcriptional activation domain of c-Rel in vivo, we generated mice expressing a truncated c-Rel (Deltac-Rel) that lacks the COOH-terminal region, but retains a functional Rel homology domain. Mice with an homozygous mutation in the c-rel region encoding the COOH terminus of c-Rel (c-relDeltaCT/DeltaCT) display marked defects in proliferative and immune functions. c-relDeltaCT/DeltaCT animals present histopathological alterations of hemopoietic tissues, such as an enlarged spleen due to lymphoid hyperplasia, extramedullary hematopoiesis, and bone marrow hypoplasia. In older c-relDeltaCT/DeltaCT mice, lymphoid hyperplasia was also detected in lymph nodes, liver, lung, and stomach. These animals present a more severe phenotype than mice lacking the entire c-Rel protein. Thus, in c-relDeltaCT/DeltaCT mice, the lack of c-Rel activity is less efficiently compensated by other NF-kappaB proteins.

Gastric hyperplasia and increased proliferative responses of lymphocytes in mice lacking the COOH-terminal ankyrin domain of NF-kappaB2

The nfkb2 gene encodes the p100 precursor which produces the p52 protein after proteolytic cleavage of its COOH-terminal domain. Although the p52 product can act as an alternative subunit of NF-kappaB, the p100 precursor is believed to function as an inhibitor of Rel/NF-kappaB activity by cytoplasmic retention of Rel/NF-kappaB complexes, like other members of the IkappaB family. However, the physiological relevance of the p100 precursor as an IkappaB molecule has not been understood. To assess the role of the precursor in vivo, we generated, by gene targeting, mice lacking p100 but still containing a functional p52 protein. Mice with a homozygous deletion of the COOH-terminal ankyrin repeats of NF-kappaB2 (p100(-/-)) had marked gastric hyperplasia, resulting in early postnatal death. p100(-/-) animals also presented histopathological alterations of hematopoietic tissues, enlarged lymph nodes, increased lymphocyte proliferation in response to several stimuli, and enhanced cytokine production in activated T cells. Dramatic induction of nuclear kappaB-binding activity composed of p52-containing complexes was found in all tissues examined and also in stimulated lymphocytes. Thus, the p100 precursor is essential for the proper regulation of p52-containing Rel/NF-kappaB complexes in various cell types and its absence cannot be efficiently compensated for by other IkappaB proteins.

B cells genetically deficient in the c-Rel transactivation domain have selective defects in germline CH transcription and Ig class switching

The Ig heavy chain locus contains a number of binding sites for the transcriptional activator, c-Rel. In this study, we evaluated the capacity of B cells from mice made genetically deficient in the C-terminal, transactivation domain of the c-Rel protein (delta c-Rel) to undergo Ig class switching. Flow-cytometric and digestion circularization PCR analyses revealed that delta c-Rel B cells failed to switch to IgG3 in response to LPS alone, or to IgG1 or IgE in response to LPS + IL-4. This failure to switch to IgG3 or IgG1 was associated with a corresponding loss of germline CH gamma 3 or CH gamma 1 RNA. However, the defective switching to IgE in delta c-Rel B cells was associated with normal levels of germline CH epsilon RNA relative to control B cells. The ability of delta c-Rel B cells to switch to IgG1, in response to LPS + IL-4, could be restored through the action(s) of additional stimuli, and this was associated with induction of normal levels of germline CH gamma 1 RNA relative to controls. In contrast, LPS-activated B cells from delta c-Rel mice underwent normal switching to IgA in the presence of TGF-beta, relative to control B cells. This was associated with equivalent steady state levels of germline CH alpha RNA between the two B cell populations. These data are the first to demonstrate a key and selective role for c-Rel in the regulation of Ig class switching. Furthermore, distinct differences are revealed in the Ig isotype induction profiles of B cells lacking c-Rel activity vs those deficient in p50/nuclear factor-kappa B.

B cells genetically deficient in the c-Rel transactivation domain have selective defects in germline CH transcription and Ig class switching

The Ig heavy chain locus contains a number of binding sites for the transcriptional activator, c-Rel. In this study, we evaluated the capacity of B cells from mice made genetically deficient in the C-terminal, transactivation domain of the c-Rel protein (delta c-Rel) to undergo Ig class switching. Flow-cytometric and digestion circularization PCR analyses revealed that delta c-Rel B cells failed to switch to IgG3 in response to LPS alone, or to IgG1 or IgE in response to LPS + IL-4. This failure to switch to IgG3 or IgG1 was associated with a corresponding loss of germline CH gamma 3 or CH gamma 1 RNA. However, the defective switching to IgE in delta c-Rel B cells was associated with normal levels of germline CH epsilon RNA relative to control B cells. The ability of delta c-Rel B cells to switch to IgG1, in response to LPS + IL-4, could be restored through the action(s) of additional stimuli, and this was associated with induction of normal levels of germline CH gamma 1 RNA relative to controls. In contrast, LPS-activated B cells from delta c-Rel mice underwent normal switching to IgA in the presence of TGF-beta, relative to control B cells. This was associated with equivalent steady state levels of germline CH alpha RNA between the two B cell populations. These data are the first to demonstrate a key and selective role for c-Rel in the regulation of Ig class switching. Furthermore, distinct differences are revealed in the Ig isotype induction profiles of B cells lacking c-Rel activity vs those deficient in p50/nuclear factor-kappa B.

IkappaBalpha overexpression delays tumor formation in v-rel transgenic mice

We have previously shown that transgenic mice expressing the oncoprotein v-Rel under the control of a T cell-specific promoter develop T cell lymphomas. Tumor formation was correlated with the presence of p50/v-Rel and v-Rel/v-Rel nuclear kappaB-binding activity. Since experimental evidence has led to the suggestion of a potential tumor suppressor activity for IkappaBalpha, we have studied the role of IkappaBalpha in the transforming activity of v-Rel by overexpressing IkappaBalpha in v-rel transgenic mice. Overexpression of IkappaBalpha in v-rel transgenic mice resulted in an extended survival, and the development of cutaneous T cell lymphomas of CD8(+)CD4(-) phenotype. These phenotypic alterations were associated with a dramatic reduction of p50/v-Rel, but not v-Rel/v-Rel nuclear DNA binding activity and an increased expression of the intercellular adhesion molecule 1. Our results indicate that v-Rel homodimers are active in transformation and that the capacity of v-Rel-containing complexes to escape the inhibitory effect of IkappaBalpha may be a key element in its transforming capability.

Hyperlipidemia in liver transplant recipients: prevalence and risk factors

Hyperlipidemia is common in transplant patients. Although a causal relationship to the use of cyclosporine is accepted, additional risk factors are as yet unidentified. Eighty-five liver transplant recipients treated with standard triple immunosuppression with a survival of at least 6 months were evaluated. Pretransplantation and posttransplantation variables were analyzed as predictive factors of posttransplantation hyperlipidemia. Serum cholesterol and triglyceride levels were considered elevated if they were > 250 mg/dL and > 150 mg/dL, respectively. Before and after transplantation, hyperlipidemia occurred in 8% (95% confidence interval [CI], 3% to 16%) and 66% (95% CI, 55% to 76%), respectively. After transplantation, 47% (95% CI, 36% to 58%) of the patients had isolated high triglyceride levels, 12% (95% CI, 6% to 21%) had both elevated cholesterol and triglyceride levels, and 7% (95% CI, 3% to 15%) had isolated elevated cholesterol levels. Hypertriglyceridemia occurred early after transplantation (67% by first month) and persisted nearly unchanged throughout the first year. In contrast, cholesterol levels increased with time (5%, 13%, and 27% at 1, 3, and 6 months, respectively). In univariate analysis, factors predictive of hypercholesterolemia included female sex, pretransplantation cholestatic liver disease, pretransplantation cholesterol levels > 141 mg/dL, and > 3 methylprednisolone "boluses." In multivariate analysis, only a pretransplantation cholesterol level of > 141 mg/dL (odds ratio [OR], 5.5; 95% CI, 1.4 to 21) was an independent risk factor. Risk factors associated with hypertriglyceridemia included pretransplantation hepatocellular liver disease (OR, 6.8; 95% CI, 1.2 to 40) and posttransplantation renal dysfunction (OR, 5.4; 95% CI, 1.9 to 15.4). Hyperlipidemia is a frequent finding in liver transplant recipients, and hypertriglyceridemia is the most common abnormality. Hypertriglyceridemia can be predicted on the basis of pretransplant hepatocellular disease and posttransplant renal dysfunction. Pretransplant serum cholesterol level is an independent risk factor for posttransplant hypercholesterolemia.

Genetic approaches to study Rel/NF-kappa B/I kappa B function in mice

The generation of animal models in which individual members of a gene family are genetically altered is a particularly attractive way to elucidate their function-Members of the Rel/NF-kappa B/I kappa B family constitute an important network of transcription factors and regulatory proteins that control the expression of numerous cellular and viral genes crucial for a variety of processes. A few examples are developmental pattern formation and immune response in Drosophila, viral replication, and immune, inflammatory, acute phase and stress responses in vertebrates. The findings from knockout and transgenic mice developed to study Rel/NF-kappa B/I kappa B function in vivo are reviewed here. In general, these studies point to the essential role of these factors in the development and function of the vertebrate immune system.

Disruption of the erp/mkp-1 gene does not affect mouse development: normal MAP kinase activity in ERP/MKP-1-deficient fibroblasts

Externally regulated phosphatase (ERP or MKP-1) is a dual specificity phosphatase that has been implicated in the dephosphorylation of mitogen activated protein kinases (MAP kinases). MAP kinase is activated in response to external signals and in turn phosphorylates proteins essential to the regulation of cell growth. To study the role of ERP/MKP-1 protein in mammalian development and its function in signal transduction we have generated mice, embryonic stem (ES), cells and mouse embryo fibroblasts (MEFs) that are deficient in the ERP/MKP-1 protein. ERP/MKP-1-deficient mice are born at normal frequency, are fertile and present no phenotypic or histologic abnormalities. MAP kinase activity and the induction of c-fos mRNA is unaltered in MEFs lacking the ERP/MKP-1 protein, indicating no alteration of the MAP kinase pathway. In addition, ERP/MKP-1 deficient MEFs grow and enter DNA synthesis at the same rate as control cells. Our results demonstrate that the activity of ERP/MKP-1 is not essential for embryo development and indicate that the lack of ERP/MKP-1 activity can be compensated by other phosphatases in vivo.

The v-rel oncogene promotes malignant T-cell leukemia/lymphoma in transgenic mice

The oncogene product from the avian reticuloendotheliosis virus strain T, v-Rel, is a member of the Rel/ NF-kappa B family of transcription factors. The mechanism by which v-Rel induces oncogenic transformation remains unclear. Several attempts to transform mammalian cells with v-Rel have failed, suggesting that v-Rel transformation may be a species-specific event. However, here we demonstrate that v-Rel, but not a truncated c-Rel, expressed under the control of the lck promoter, efficiently induced malignancies in transgenic mice. Most of the animals died before 10 months of age and developed immature, multicentric aggressive T-cell leukemia/lymphomas. Most tumors contain CD4+CD8+ cells or CD4-CD8+ cells, which have an immature rather than a mature peripheral phenotype. No tumor development was observed in control littermates and transgenic mice expressing a truncated form of c-Rel. Tumor formation was correlated with the presence of constitutive p50/v-Rel DNA binding activity and overexpression of several kappa B-regulated genes in v-rel transgenic thymocytes. However, v-Rel is also transforming in transgenic thymocytes lacking p50, indicating that p50/v-Rel heterodimer formation is not essential for the transforming activity of v-Rel. The transforming activity of v-Rel in p50 null mice has been identified as v-Rel/v-Rel homodimers. Since tumors represent immature T-lymphocytes, constitutive v-Rel expression appears to be leukemogenic at earlier stages of T-cell development. These v-Rel mice should aid in the study of lymphoma development, T-cell development and NF-kappa B regulation.

RelB, a member of the Rel/NF-kappa B family of transcription factors

RelB, originally identified as an immediate early gene product, is a member of the Rel/NF-kappa B family of transcription factors important for the regulation of genes involved in immune and inflammatory processes. RelB by itself is inactive due to its inability to homodimerize and to bind to kappa B sequences. However, in the presence of the Rel/NF-kappa B proteins p50 or p52, RelB is a potent transactivator. Transcriptional activation domains were identified in the NH2 and COOH termini of RelB separated by the approximately 300 amino acids spanning the Rel homogy domain (RHD). The last 120 amino acids of this domain are necessary for the dimerization of RelB and were analyzed in detail by in vitro mutagenesis. RelB forms complexes with p50 and p52 but not with RelA and c-Rel. In contrast to RelA-containing complexes, RelB-containing complexes are only weakly inhibited in their activity by I kappa B alpha. Furthermore, in lymphoid tissues RelB is not associated with I kappa B alpha. In contrast to other members of the Rel/NF-kappa B family, high expression of RelB is limited to interdigitating dendritic cells. Mice with a targeted disrupted relB locus show phenotypic abnormalities including multifocal, mixed inflammatory cell infiltration in several organs, myeloid hyperplasia, splenomegaly due to extramedullary hematopoiesis, and a reduced population of thymic dendritic cells.

Genome detection in liver and peripheral blood mononuclear cells: predictor factors of sustained response in patients with chronic hepatitis C

BACKGROUND

In chronic hepatitis C, relapses of liver disease occur in as many as 50% of patients responding to interferon (IFN) therapy. Although the presence of serum hepatitis C virus (HCV) RNA at the end of therapy predicts a relapse, its absence is not a reliable indicator of cure. In this study we have determined whether responders to IFN (normalization of liver chemistry and clearance of serum HCV-RNA) harbour HCV-RNA in the liver and peripheral blood mononuclear cells (PBMCs), and whether finding the genome at these sites has prognostic significance.

METHODS

After the conclusion of therapy, we tested for HCV-RNA in the liver of all the patients (anti-HCV-positive): 16 complete responders with normalization of liver chemistry and clearance of serum HCV-RNA and five non-responders. In 13 of the 16 complete responders we also tested for HCV-RNA in PBMCs. Patients were followed up for 9 months.

RESULTS

Liver HCV-RNA was detected in each of the five non-responders and in four of the 16 complete responders (25%). The viral genome was detected in the PBMCs of six complete responders (46%). During follow-up a relapse of hepatitis C occurred in the 10 complete responders with liver or PBMC HCV-RNA but in only one (16%) of the six complete responders without HCV-RNA in liver or PBMCs.

CONCLUSION

Reliable information on the prognosis of chronic hepatitis C responders can only be obtained by testing for HCV-RNA in serum, liver and PBMCs at the end of therapy. Patients with HCV-RNA at any of these sites stand a high risk of disease relapse. The risk is low but not abolished in patients without detectable HCV-RNA.

[Focal nodular hyperplasia of the liver: benign lesion with often surgical treatment. Magnetic resonance and laparoscopic findings]

The diagnosis of benign hepatic tumor lesions is every day more frequent. Three cases of focal nodular hyperplasia (FNH) accidently detected during the performance of echography and/or CAT for other reasons are presented. The difficulty or diagnostic doubts which the different imaging techniques may present before these findings, together with the relatively young age of these patients may lead to the adoption of a surgical attitude in lesions of a clearly benign character. The role of magnetic resonance (MR) as a non invasive diagnostic technique in this type of disease is of note.

Does the healthy hepatitis C virus carrier state really exist? An analysis using polymerase chain reaction

To determine whether the presence of hepatitis C virus (HCV) viremia correlates with the severity of liver disease in anti-HCV-positive apparently healthy blood donors, we studied 98 blood donors found positive for anti-HCV using enzyme-linked immunosorbent assay (ELISA). Each subject underwent a liver biopsy, a test for HCV RNA in the serum by polymerase chain reaction (PCR), and a panel of liver injury tests. As a result, 97% of the anti-HCV-positive blood donors had some type of histological abnormality:22 (22%) had minimal changes, 1 (1%) had chronic lobular hepatitis, 40 (41%) had chronic persistent hepatitis (CPH), and 32 (33%) had chronic active hepatitis (CAH). Only 3 subjects had a normal liver histology. HCV RNA was detectable in the serum in 65% of the anti-HCV-positive donors. HCV RNA in serum was detectable in none of the donors with a normal liver histology, in 36% (confidence interval [CI], 17% to 59%) of those with minimal changes, in 70% (CI, 53% to 83%) of those with CPH, and in 87% (CI, 71% to 96%) of those with CAH (P = .00001). HCV RNA was detectable in 75% of the donors with elevated (> 45 U/L) alanine transaminase (ALT) values and in 59% of those with normal ALT levels (P = not significant). The incidence of chronic hepatitis was higher in HCV RNA-positive than in HCV RNA-negative donors (88% vs. 50%; P = .00005).(ABSTRACT TRUNCATED AT 250 WORDS)

Tissue-specific expression of the fos-related transcription factor fra-2 during mouse development

The fra-2 gene is related to the proto-oncogene c-fos and encodes a member of the AP-1 transcription factor gene family. We have studied the expression of fra-2 during mouse embryonic development and compared it to the pattern of expression of other fos and jun family members. By in situ hybridization and immunohistochemical analysis we have shown fra-2 expression during late organogenesis. fra-2 transcripts are detected in several differentiating epithelia, developing cartilage and central nervous system. The pattern of fra-2 expression is distinct from that observed for other fos related genes, suggesting that fra-2 has a unique role in cellular differentiation during fetal development.

Multiorgan inflammation and hematopoietic abnormalities in mice with a targeted disruption of RelB, a member of the NF-kappa B/Rel family

RelB, a member of the NF-kappa B/Rel family of transcription factors, has been implicated in the constitutive expression of kappa B-regulated genes in lymphoid tissues. We have generated mice carrying a germline mutation of the relB gene, resulting in the absence of RelB protein and a dramatic reduction of constitutive kappa B-binding activity in thymus and spleen. Mice homozygous for the disrupted relB locus had phenotypic abnormalities including multifocal, mixed inflammatory cell infiltration in several organs, myeloid hyperplasia, splenomegaly due to extramedullary hematopoiesis, and a reduced population of thymic dendritic cells. RelB-deficient animals also had an impaired cellular immunity, as observed in contact sensitivity experiments. Thus, RelB plays a decisive role in the hematopoietic system, and its absence cannot be functionally compensated by any other member of the NF-kappa B/Rel family.

Expression of the chemokine N51/KC in the thymus and epidermis of transgenic mice results in marked infiltration of a single class of inflammatory cells

Transgenic mice expressing the chemokine N51/KC in thymus, skin, and tongue showed a marked infiltration of a single class of inflammatory cells (neutrophils) in the sites of transgene expression. In the thymus, neutrophils were most numerous in the cortex and juxta-medullary regions, often forming aggregates or clusters. A similar, but less intense, neutrophilic infiltrate occurred in close proximity to the epidermal basal layer of the tongue and skin. No morphologic evidence of injury was observed in the thymus, skin, or tongue of these transgenic mice, indicating that N51/KC expression induces recruitment but not inflammatory activation of neutrophils. The lack of activation in the thymus resulted in a large senescent neutrophilic population that was phagocytosed by thymic macrophages and epithelial-reticular cells. These results indicate that N51/KC is a neutrophil chemoattractant in vivo and establish these transgenic mice as effective models to study the phenomena of recruitment and clearance of neutrophils, events that are critical for the initiation and resolution of the inflammatory response.

Constitutive and inducible Rel/NF-kappa B activities in mouse thymus and spleen

We have studied the expression of members of the rel family of transcription factors and ikba in mouse thymus and spleen by in situ hybridization. Our results show that the rel genes have different temporal and spatial patterns of expression suggesting distinct roles in these lymphoid tissues. The Rel/NF-kappa B proteins and I kappa B alpha in thymus and spleen were also analysed by Western blotting and electrophoretic mobility shift assays. Although RelB protein is present at significantly lower levels in thymus and spleen extracts when compared to RelA, in both tissues the predominant kappa B-binding activity consists of p50/RelB and p52/RelB heterodimers and only very little binding of RelA-containing complexes to kappa B sites was detected. Significant binding of c-Rel complexes was only found in spleen extracts. Treatment of thymus and spleen extracts with deoxycholate (DOC), however, results in a strong increase in binding to kappa B sites of both RelA and c-Rel complexes. In contrast, binding of RelB complexes is not induced after DOC treatment. Our results suggest a differential role of Rel/NF-kappa B complexes in mouse thymus and spleen with RelB heterodimers representing the constitutive kappa B-binding activity, whereas RelA and c-Rel complexes most likely are involved in inducible kappa B-binding and gene activation.

Developmental expression of the mouse c-rel proto-oncogene in hematopoietic organs

We have studied the expression of the c-rel proto-oncogene during mouse embryonic development and adult animals using in situ hybridization and immunocytochemical analysis. c-rel transcripts were detected late in development with an expression pattern that parallels the emergence and diversification of hematopoietic cells. In the embryo, c-rel is expressed first in the mesoderm-derived hematopoietic cells of the liver and later also in other hematopoietic tissues such as thymus and spleen. This correlation between c-rel expression and places of hematopoietic infiltration is conserved in the postnatal period, with expression of c-rel mRNA in the medullary region of the thymus and in splenic B cell areas, including the marginal zone and the outer region of the periarterial sheath. High levels of c-rel transcripts were also detected in the splenic germinal centers, lymph nodes and Peyer's patches. Using double immunofluorescence and cell preparations from different embryonic and adult hematopoietic organs, we have defined the pattern and cell types of c-rel expression in different hematopoietic cell lineages and in the stromal cell content of the thymus. By using electrophoretic mobility shift assays, we have also correlated c-Rel expression in spleen with kappa B-binding activity in the form of c-Rel/p50 and c-Rel/p52 heterodimers. The timing and pattern of expression of the c-rel proto-oncogene in the different cell lineages suggest that temporally regulated changes in c-Rel expression may be required for vertebrate hematopoiesis.

Expression of the nontransmembrane tyrosine phosphatase gene erp during mouse organogenesis

We have studied the expression of the nontransmembrane tyrosine phosphatase gene erp during mouse development using in situ hybridization analysis. The results show that during the early postimplantational stages of development, erp expression is observed only in maternally derived decidual cells surrounding the developing embryo. At day 10.5, erp is weakly expressed in the embryo in the neural tube, hind gut, and other embryonic structures. However, in 12.5-day embryos, erp is present in most organs, with the highest expression restricted to the developing neural system. During later development, at day 17.5, the levels of erp decline in some neural structures but remain high in others, like the dorsal root ganglia. High levels of erp expression are maintained in several parts of adult brain, such as cortical layers, thalamus, hypothalamus, and hippocampus. High levels of erp transcripts are also observed in the cerebellar cortex, in the Purkinje cell layer, and in the granular cell layer. In all tissues analyzed, the expression of erp corresponds to regions undergoing terminal cell differentiation and/or regions where cell proliferation has declined.

Structure, mapping, and expression of erp, a growth factor-inducible gene encoding a nontransmembrane protein tyrosine phosphatase, and effect of ERP on cell growth

We have characterized a growth factor-inducible gene, erp, and demonstrated that it encodes a 367-amino-acid nontransmembrane tyrosine phosphatase protein with significant similarity to the vaccinia virus H1 protein. Immunoprecipitation analyses show that the erp protein, ERP, is rapidly induced following serum stimulation of quiescent fibroblasts. ERP has been expressed as a fusion protein with glutathione S-transferase and shown to have tyrosine as well as serine protein phosphatase activity. The enzymatic activity of ERP depends on the presence of reducing agents such as dithiothreitol, and its tyrosine phosphatase activity is inhibited by sodium vanadate, a potent inhibitor of protein tyrosine phosphatases. The number of stable NIH 3T3 clones obtained after transfection with a vector expressing the complete ERP protein is reduced more than 90% compared with that after transfection with a vector expressing a mutated inactive ERP protein. The remaining ERP-expressing clones present a significant increase in the proportion of bi- and multinucleated cells and a decrease in proliferation rate. Studies on the genomic structure reveal that the erp transcription unit is 2.8 kbp long and split into four exons. The erp gene maps to the 17A2-17C region of the murine genome. Our results demonstrate that the protein product of the immediate-early gene erp has a negative effect on cell proliferation.

Expression of relB transcripts during lymphoid organ development: specific expression in dendritic antigen-presenting cells

We have studied the expression of the relB gene during mouse development using in situ hybridization and immunocytochemical analysis. The results show that the expression of the relB gene is highly restricted to a subpopulation of cells that colonize the lymphoid tissues and that appear very late during the process of hematopoietic diversification. RNA transcripts of relB are very low or undetectable in early and late embryos. Low relB expression is observed in the thymus at late stages of embryogenesis but rapidly increases after birth. In adult lymphoid tissues, relB is detected in the medullary region of the thymus, the periarterial lymphatic sheaths of the spleen, and the deep cortex of the lymph nodes, which correspond to the regions where T cells of mature phenotype and interdigitating dendritic cells are present. Using double immunofluorescent labeling of thymic cell suspensions, we have identified the interdigitating dendritic cells as the target of RelB expression. These cells are part of a system of antigen-presenting cells that function in the induction of several immune responses, such as, tolerance, sensitization of MHC-restricted T cells, rejection of organ transplants and formation of T-dependent antibodies. Our observations indicate that RelB may play a particular role in the signal transduction pathway that regulate dendritic cell differentiation and its cellular responses.

Developmental expression of the vav protooncogene

We have examined the expression of the vav protooncogene during mouse embryogenesis using RNase protection assays, in situ hybridization, and immunocytochemical analysis. vav gene transcripts were first detected in E11.5 embryos in the blood-forming islands and megakaryocytes of the fetal liver. During diversification of hematopoietic activity in the embryo, vav gene expression became down-regulated in the liver and activated in thymus and spleen. In newborn animals, vav expression was also confined to hematopoietic tissues, with the exception of the ameloblastic cell layer at the latest stages of tooth morphogenesis. In the adult, vav transcripts were found in spleen, thymus, lymph nodes, and bone marrow, but not in liver. In spleen, vav transcripts were concentrated in the white pulp areas, whereas in the red pulp, the vav transcripts appeared to be primarily localized in the megakaryocytes. In thymus, vav expression was found to be more abundant in the cortical areas than in the medulla. In agreement with these observations, purified thymic lymphocytes showed heterogeneous immunoreactivity against the Vav protein, whereas splenic lymphocytes and bone marrow-derived cells displayed rather uniform levels of expression. These observations suggest that the vav protooncogene plays an important role in the signal transduction pathways that regulate the development and maintenance of the hematopoietic system.

The incorporation of myo-inositol into phosphatidylinositol derivatives is stimulated during hormone-induced meiotic maturation of amphibian oocytes

The incorporation of myo-[3H]inositol into phosphatidylinositol and its phosphorylated derivatives was studied by microinjection of the radioactive precursor into Xenopus laevis oocytes. Induction of meiotic maturation of the oocytes by treatment with either progesterone one or insulin resulted in a significant increase in the incorporation of myo-[3H]inositol into the phospholipid fraction. This increase occurred 3-6 h after hormonal treatment, a time coincident with the start of the breakdown of the nuclear envelope, and requires protein synthesis. The effect of progesterone and insulin contrasts with the effect of acetylcholine, which acts through a muscarinic receptor causing the activation of phospholipase C, since the latter effector causes an increase in myo-[3H]inositol incorporation, which is more rapid and does not require protein synthesis. These results suggest that the meiotic maturation process is connected with changes in inositol metabolism in the amphibian oocyte.