Topical diclofenac does not affect the antiplatelet properties of aspirin as compared to the intermediate effects of oral diclofenac: A prospective, randomized, complete crossover study.

Nonsteroidal anti-inflammatory drugs (NSAIDs) adversely interact with aspirin, diminishing its antiplatelet effect and potentially placing patients at an increased risk for recurrent thrombotic events. This crossover study aimed to determine whether the topical NSAID diclofenac epolamine 1.3% patch or oral diclofenac 50 mg interfered with the antiplatelet effects of aspirin 325 mg. Twelve healthy men and women aged 18-50 were included. Participants were randomized into 5 treatment arms: aspirin, diclofenac potassium 50 mg, diclofenac patch, diclofenac potassium plus ASA 325 mg, and diclofenac patch plus aspirin. Platelet responsiveness was determined using whole-blood impedance aggregation (WBA) to collagen 1 µg/mL and arachidonic acid (AA) 0.5 mM and was sampled every 2 hours. No significant difference in platelet function was observed following the diclofenac patch and aspirin vs aspirin alone. Oral diclofenac produced a mixed effect with significant reduction in platelet inhibition at hour 2 and hour 8 following aspirin administration. Topical diclofenac does not significantly interfere with the antiplatelet effects of aspirin and may be a safer alternative to the oral formulation.

Adverse effects of intradermal allogeneic lymphocyte immunotherapy: acute reactions and role of autoimmunity.

BACKGROUND: Immunotherapy with allogeneic lymphocytes was introduced as a therapeutic option for selected infertile couples in different centres worldwide 20 years ago. It has been suggested for other indications as well, e.g. for pregnant women at risk of a child with Rhesus-D haemolytic disease, or as a vaccine which might reduce the receptiveness for HIV-1 infection. Here we report on our experience on adverse side-effects of intradermal lymphocyte immunotherapy (LIT) for infertile couples using partner's lymphocytes. METHODS: Prospective 4 week follow-up of all couples from 2000 to 2003 for acute reactions (feedback 2687/3246 [corrected] 83%). All couples treated between 1996 and 2002 received questionnaires after 2-3 years (feedback 1914/3041, 63%). RESULTS: Local reactions predominantly consisted of redness and itching for approximately 2 weeks. Systemic reactions could be attributed to LIT in 6-8%. Blisters at the injection sites were characteristic of LIT but not dependent on the HLA class I mismatch status between cell donor and host. The incidence of autoimmune disease was 0.1%. Four patients developed thromboembolism in pregnancy which was not ascribed to antiphospholipid syndrome. CONCLUSIONS: Acute side-effects are comparable to those reported after intradermal vaccination for infectious diseases. Specific risks for anaphylaxis, autoimmune or graft versus host disease were not detected.

Self-deleting suicide vectors (SDSV): selective killing of p53-deficient cancer cells.

A self-deleting retrovirus vector carrying a herpes simplex virus (HSV)-thymidine kinase suicide gene has been developed to selectively kill cancer cells expressing a dysfunctional p53 tumor suppressor protein. When cells containing functional p53 are infected with the virus, the integrated provirus and the HSV-thymidine kinase gene are deleted from the genome by site-specific recombination (Cre/loxP). In contrast, cells without p53 or cells expressing a DNA-binding mutant of p53 retain the provirus and become susceptible to killing by ganciclovir. This strategy provides a new concept for the selective killing of cancer cells that can be adapted to any other dysfunctional transcription factor expressed by different tumors.

Evaluation of CoaguChek Pro ACT in cardiac catheterization laboratory.

The objective of this study was to assess the analytical performance of CoaguChek Pro ACT assay versus Hemochron Celite ACT assay concerning activated clotting time (ACT) values and the correlations versus heparin. Enrolled were 158 patients and 101 normal subjects from five cardiac catheterization laboratories (cathlabs). Two different CoaguChek Pro ACT lots were compared to different lots of Hemochron Celite ACT. All sites used arterial blood and one site also used venous blood. Determinations were carried out before and directly after heparinization, and 1-4 h later. Besides the ACT values, hematocrit, platelet counts and factor Xa levels were also determined. The correlations between the Hemochron Celite lots and the two different CoaguChek Pro lots for arterial and venous blood for all sites were good (r=0.88 and 0.84). The agreement between both CoaguChek Pro ACT lots was excellent (r=0.99). The correlations between heparin and CoaguChek Pro ACT were similar to those for the Hemochron Celite lots. There was no influence of the hematocrit and the platelets. The imprecision of the method was very good (CV<6%). This demonstrates that the CoaguChek Pro ACT assay is especially useful for monitoring heparin in cathlabs.

Interleukin-1 and related proteins in cardiovascular disease in adults and children.

Interleukin-1 (IL-1) is a key mediator in the cytokine network, controlling important functions in the immune system, during development, infection, inflammation, cell-differentiation, tissue remodelling, and even cell death. The agonistic isoforms of IL-1 (i.e., IL-1alpha and IL-1beta), the IL-1 receptor antagonists, the receptors and receptor-associated proteins, as well as the recently identified IL-18 and its receptor belong to the IL-1 family of proteins. Activation of the IL-1beta and IL-18 precursors is performed enzymatically by caspase-1, previously termed IL-1beta-converting enzyme (ICE). This molecule is the founding member of the caspase family of enzymes, which are involved in maturation of cytokines and in initiation and execution of apoptotic processes. It has been suggested that cytokines and apoptosis are involved in pathogenesis of cardiovascular diseases such as atherosclerosis, chronic heart failure, myocarditis, cardiomyopathy, or stroke. Since IL-1, like TNF, is a central mediator in the cytokine network, it may act as a potent activator of cardiovascular cells. We know that cells of the vessel wall and the heart can produce IL-1 and respond to this mediator by production of other cytokines or regulation of other cardiovascular cell functions. Thus, this report summarizes general information about the molecules of the IL-1 family of proteins, including the caspases, as well as data regarding these proteins in relation to the vessel wall and the heart and their role in cardiovascular disease in adults and children. The summarized information indicates a role of these molecules in regulation of local inflammatory responses during cardiovascular disease.

Activation of lytic Epstein-Barr virus (EBV) infection by radiation and sodium butyrate in vitro and in vivo: a potential method for treating EBV-positive malignancies.

The consistent presence of the EBV genome in certain tumors offers the potential for novel EBV-directed therapies. Switching the latent form of EBV infection present in most EBV-positive tumor cells into the cytolytic form may be clinically useful because lytic EBV infection leads to host cell destruction, and very few normal cells contain the EBV genome. It would also be therapeutically advantageous to induce expression of EBV-encoded lytic proteins that convert the nucleoside analogues ganciclovir (GCV) and 3'-azido-3'deoxythymidine (AZT) into their active, cytotoxic forms. In this report, we have explored two different approaches for activating the lytic form of EBV infection in tumors. We show that gamma-irradiation at clinically relevant doses induces lytic EBV infection in lymphoblastoid cell lines in vitro as well as in EBV-positive B-cell tumors in SCID mice. In addition, sodium butyrate (given as a single i.p. dose) is effective for activating lytic viral infection in some EBV tumor types in SCID mice. We also examined whether low-dose gamma-irradiation treatment of EBV-positive lymphoblastoid cells in vitro promotes GCV or AZT susceptibility. The combination of radiation with either GCV or AZT induced significantly more cell killing in vitro than either radiation or prodrug treatment alone. Most importantly, we found that the combination of gamma-irradiation and GCV was much more effective in treating EBV-positive lymphoblastoid tumors in SCID mice than either agent alone. Thus, GCV or AZT treatment could potentially enhance the therapeutic efficacy of radiation therapy for EBV-positive lymphomas in patients.

Bypassing hybridoma technology: HLA-C reactive human single-chain antibody fragments (scFv) derived from a synthetic phage display library (HuCAL) and their potential to discriminate HLA class I specificities.

The generation of discriminative, monospecific anti-HLA antibodies used to be a difficult endeavor. Phage display technology, using single-chain antibody fragments (scFv) offers a powerful alternative obtaining target-specific, genetically stable reagents. Most of scFv obtained to date have been enriched by panning phage libraries to solid-phase coupled antigens. In the present study, HLA-C-specific scFv were isolated using a synthetic phage library in combination with a Cw*0602 overexpressing cell line. ScFv from this procedure precipitated HLA-Cw*0602 heavy chains from whole cell lysates. Flow cytometry analysis revealed that scFv stained HLA-Cw*0602-positive cells, but not cells expressing HLA alleles Cw*0302, Cw*0802, A*0201, B*2705, or Gm1*01011, indicating the specificity of scFv. Similarly they showed an ability to discriminate Cw*0602-positive from Cw*0602-negative peripheral blood lymphocytes (PBL). The results of our study demonstrate the feasibility to genetically engineer single-chain HLA-class I-specific antibodies, by phage display technology. This approach might be a valuable tool to develop a broad range of novel monospecific antibodies against HLA-class I specificities.

Localization of psoriasis-susceptibility locus PSORS1 to a 60-kb interval telomeric to HLA-C.

Recent genome scans have established the presence of a major psoriasis-susceptibility locus in the human leukocyte antigen (HLA) complex on chromosome 6p21.3. To narrow the interval for candidate gene testing, we performed a linkage-disequilibrium analysis of 339 families, with the use of 62 physically mapped microsatellite markers spanning the major histocompatibility complex (MHC). As detected by use of the transmission/disequilibrium test (TDT), individual markers yielded significant linkage disequilibrium across most of the MHC. However, the strongest evidence for marker-trait disequilibrium was found in an approximately 300-kb region extending from the MICA gene to the corneodesmosin gene. Maximum-likelihood haplotypes were constructed across the entire MHC in the original sample and across a 1.2-Mb region of the central MHC in an expanded sample containing 139 additional families. Short (two- to five-marker) haplotypes were subjected to the TDT using a "moving-window" strategy that reduced the variability of TDT P values relative to the single-locus results. Furthermore, the expanded sample yielded a sharp peak of evidence for linkage disequilibrium that spanned approximately 170 kb and that was centered 100 kb telomeric to HLA-C. The 1.2-Mb interval was further dissected by means of recombinant ancestral haplotype analysis. This analysis identified risk haplotype 1 (RH1), which is a 60-kb fragment of ancestral haplotype 57.1, on all identifiable HLA risk haplotypes. One of these haplotypes exhibits significant linkage disequilibrium with psoriasis but does not carry Cw6, which is the HLA allele most strongly associated with the disease. These results demonstrate that RH1 is highly likely to carry the disease allele at PSORS1, and they exclude HLA-C and corneodesmosin with a high degree of confidence.

The nitroreductase/CB1954 combination in Epstein-Barr virus-positive B-cell lines: induction of bystander killing in vitro and in vivo.

Epstein-Barr virus (EBV)-based gene delivery vectors that preferentially express toxic genes in EBV-infected cells could be used to target EBV-positive tumors for destruction. We have shown previously that the cytosine deaminase (CD) enzyme, which converts the prodrug 5-fluorocytosine (5-FC) into the toxic compound 5-fluorouracil efficiently kills EBV-positive cells in the presence of 5-FC, with a substantial bystander killing effect in vitro and in vivo. To identify the optimal enzyme/prodrug combination for treating EBV-positive lymphomas, we have compared the effectiveness of the CD/5-FC combination with the nitroreductase (NTR)/CB1954 combination for killing EBV-positive B-cell lines. NTR metabolizes CB1954 into an alkylating agent that cross-links DNA. When the CD gene or the NTR gene were transfected into two different EBV-positive B-cell lines in vitro, approximately 90% of cells were killed in a prodrug-dependent manner, although the transfection efficiency was <5%. However, severe combined immunodeficient mouse tumors containing either 30% or 100% of NTR-expressing Burkitt lymphoma (Jijoye) cells were growth inhibited, but not cured, by treatment with intraperitoneal CB1954 (20 mg/kg/day) for 10 days. These results suggest that the NTR/CB1954 combination induces efficient bystander killing of EBV-positive B-cell lines in vitro but may not be as effective as the CD/5-FC combination for treating B-cell lymphomas in vivo.

Corneodesmosin gene polymorphism demonstrates strong linkage disequilibrium with HLA and association with psoriasis vulgaris.

Corneodesmosin (CD) is thought to play a key role in corneocyte cohesion, and its proteolysis appears to be a major event in the process of desquamation. Recently it was shown that CD is encoded by the S-gene, which is located approximately 160 kb telomeric of HLA-C. In the present study, the role of CD in the genetics of psoriasis vulgaris was studied in greater detail. The second exon of the CD gene was sequenced in 86 HLA-typed individuals from 13 psoriasis multiplex families. A total of 11 silent dimorphisms and 7 variants resulting in amino acid substitutions were found. Pedigree analysis showed that these variants could be grouped into 7 alleles, encoding 6 different amino acid sequences. These alleles are in strong linkage disequilibrium with HLA-B and -C, indicating that the polymorphism of the CD gene is ancient and well conserved rather than sporadic. One allele at the CD locus, designated CD2, displayed strong linkage disequilibrium with HLA-Cw6, the HLA allele most prominently associated with psoriasis. CD2 demonstrated a greater relative risk than Cw6 (3.4 vs. 2.5, not significant) and higher significant transmission disequilibrium with psoriasis than any of the investigated HLA-alleles. Due to its biologic function, cellular location and disease association, the CD gene appears to be an excellent candidate gene for PSORS1, the HLA-linked determinant of psoriasis vulgaris.

Induction of lytic Epstein-Barr virus (EBV) infection in EBV-associated malignancies using adenovirus vectors in vitro and in vivo.

The consistent presence of EBV genomes in certain tumor types (in particular, AIDS-related central nervous system lymphomas and nasopharyngeal carcinomas) may allow novel, EBV-based targeting strategies. Tumors contain the latent (transforming) form of EBV infection. However, expression of either of the EBV immediate-early proteins, BZLF1 and BRLF1, is sufficient to induce lytic EBV infection, resulting in death of the host cell. We have constructed replication-deficient adenovirus vectors expressing the BZLF1 or BRLF1 immediate-early genes and examined their utility for killing latently infected lymphoma cells in vitro and in vivo. We show that both the BZLF1 and BRLF1 vectors efficiently induce lytic EBV infection in Jijoye cells (an EBV-positive Burkitt lymphoma cell line). Furthermore, lytic EBV infection converts the antiviral drug, ganciclovir (GCV), into a toxic (phosphorylated) form, which inhibits cellular as well as viral DNA polymerase. When Jijoye cells are infected with the BZLF1 or BRLF1 adenovirus vectors in the presence of GCV, viral reactivation is induced, but virus replication is inhibited (thus preventing the release of infectious EBV particles); yet cells are still efficiently killed. Finally, we demonstrate that the BZLF1 and BRLF1 adenovirus vectors induce lytic EBV infection when they are directly inoculated into Jijoye cell tumors grown in severe combined immunodeficiency mice. These results suggest that induction of lytic EBV infection in tumors, in combination with GCV, may be an effective strategy for treating EBV-associated malignancies.

Linkage disequilibrium analysis of familial psoriasis: identification of multiple disease-associated MHC haplotypes.

Although psoriasis vulgaris (PsV) is strongly associated with certain human leukocyte antigens, the pathogenetic nature of these associations remains elusive. The objectives of this study were: (i) to determine whether HLA loci directly determine susceptibility or merely serve as markers for the susceptibility allele; and (ii) to identify additional disease-associated haplotypes. By applying maximum likelihood linkage disequilibrium analysis (LDA) in cases vs. controls, we found the susceptibility gene to be more strongly associated with specific HLA haplotypes than with their component alleles. Stronger linkage disequilibrium between PsV and HLA alleles was detected at HLA-C and HLA-B than at DRB1 and DQB1. Parametric linkage analysis accounting for marker-trait disequilibrium in psoriasis vulgaris pedigrees yielded most significant results for a locus close to HLA-B and -C. Furthermore, we found that susceptibility is linked to at least three different ancestral HLA haplotypes; among them, HLA-Cw7-B8-DRB1*0301-DQB1*02 is linked to PsV for the first time. These results identify a major PsV susceptibility locus in the immediate vicinity of, but distinct from HLA-B or HLA-C, and suggest that multiple disease alleles have arisen during human evolution.

A system for shuttling 200-kb BAC/PAC clones into human cells: stable extrachromosomal persistence and long-term ectopic gene activation.

A novel shuttle vector, pBH140, has been constructed that allows stable maintenance of large genomic inserts as human artificial episomal chromosomes (HAECs) in mammalian cells. The vector, essentially a hybrid BAC-HAEC, contains an F-based replication system as in a bacterial artificial chromosome (BAC) and the Epstein-Barr virus (EBV) latent origin of replication system, oriP, for replication in human cells. A 185-kb DNA insert containing the entire human beta-globin locus, including its locus control region (LCR), was retrofitted into this vector. The resulting beta-globin BAC-HAEC clone, p148BH, was transfected into human cells and analyzed for episomal maintenance and expression of the beta-globin gene. FISH revealed an association of the vector with different human chromosomes but no integration. The beta-globin BAC-HAECs were present at an average copy number of 11-15 per nucleus in the stably transformed human cells. After 1 year of continuous in vitro cultivation, the HAECs persisted as structurally intact 200-kb episomes. While no beta-globin transcription could be detected in the parental D98/Raji cells, correctly spliced RT-PCR products were produced at significant levels in long-term cultures of the BAC-HAEC-transduced cells. The wide availability of BAC and PAC libraries, the ease in manipulating cloned DNA in bacteria, and the episomal stability of the pBH140 vector make this system ideal for studies on gene expression and other genomic functions in human cells. The potential significance of large, functionally active episomes for gene therapy is discussed.

[Cellular immune reactivity in xenogenic "human-anti-pig" transplant combination]. / Zellvermittelte Immunreaktivität in der xenogenen Transplantationskombination "Mensch-anti-Schwein".

The worldwide lack of human organ donors puts the pig as potential xenogeneic donor species into the prime of interest. Aim of the present in vitro study is the analysis of T-cell activation in the clinically attractive combination "pig-to-human". Peripheral human blood leukocytes (hPBL) and peripheral porcine blood leukocytes (pPBL) were co-cultured for 4-8 days in the xenogeneic mixed lymphocyte reaction (xMLR) and cell proliferation was measured by 3H-thymidine uptake. Both cell populations were separated into T-cells and antigen presenting cells (APC) to analyze direct and indirect antigen recognition. The results show that (a) activation of human T-cells occurs, (b) the strength of activation depends e.g. on the human responder ("high" and "low" responders), (c) the strength of activation is independent of the responder's HLA-DR status, and (d) direct T-cell activation dominates over indirect activation. Thus, T-cell activation is another immunological barrier that has to be overcome before xenotransplantation can be clinically approached.

Peripheral multifocal chorioretinitis with panuveitis: clinical and immunogenetic characterization in older patients.

BACKGROUND: The etiology of peripheral multifocal chorioretinitis with panuveitis (MCP) is unclear. Characteristic signs of MCP are punched-out, white chorioretinal lesions of the lower fundus periphery, chronic smoldering chorioretinal inflammation, vitritis, and mild inflammation of the anterior chamber. In this retrospective study we investigated clinical and immunogenetic abnormalities in MCP in older patients. PATIENTS AND METHODS: 20 patients (18 women, 2 men), median age 70.5 years, were investigated clinically by ophthalmologists and were typed for HLA class I antigens using the standard microlymphocytotoxicity test. Typing for HLA-DR antigens was performed by polymerase chain reaction with sequence-specific primers (PCR-SSP). The HLA controls consisted of healthy people (108 for HLA class I, 114 for HLA class II). RESULTS: MCP was bilateral in 18 patients. Disease-related symptoms were present for 8 months (median) before diagnosis. The main presenting symptoms or findings were glaucoma (in 11 patients), visual loss (7), iritis (5), and vitritis (2). Anterior segment changes were frequently seen: keratitic precipitates (32 eyes), anterior chamber cells (25 eyes), aqueous flare (26 eyes), posterior synechiae (22 eyes), secondary glaucoma (15 eyes), and iris neovascularization (8 eyes). All patients had vitritis and typical chorioretinal fundus lesions. Fourteen patients developed cystoid macular edema (bilateral in seven cases). Subretinal neovascularization occurred in three patients. Although systemic medication was given to 17 patients and surgical treatment was performed in 25 eyes, improvement in vision was found in only 6 eyes, but 18 eyes deteriorated markedly (median 5 lines) during follow-up (median 24.5 months). Immunogenetically significant reduced frequencies of HLA-B7 and HLA-DR1 were found; also HLD-DR15(2) was reduced. However, several alleles were increased in MCP, although not significantly: HLA-A31; HLA-B57, HLA-B62; HLA-Cw3, HLA-Cw6; HLA-DR4, HLA-DR7, and HLA-DR8. CONCLUSIONS: MCP is clinically and immunogenetically open to speculation. The present diagnosis and treatment of MCP are insufficient. Further DNA typing methods should clarify, whether HLA-DQ antigens are associated with the disease.

Gene therapy strategies for treating Epstein-Barr virus-associated lymphomas: comparison of two different Epstein-Barr virus-based vectors.

B cell lymphomas in immunocompromised patients frequently contain the Epstein-Barr virus (EBV) genome (MacMahon et al, 1991), suggesting that gene therapy strategies that target EBV-positive cells for destruction might be useful for the therapy of such tumors. We have previously shown that stable expression of the cytosine deaminase (CD) gene in EBV-positive lymphoblastoid cell lines induces cell killing in the presence of the prodrug 5-fluorocytosine, with a substantial bystander killing effect (Rogers et al., 1996). To promote specific killing of EBV-positive tumor cells, we have constructed two different EBV-based vectors containing the cytosine deaminase gene. The first vector (OriP-CD), which contains the intact EBV oriP enhancer/replication element, replicates as an episome specifically in EBV-positive cells and likewise enhances transcription in an EBV-specific manner. The OriP-CD vector cannot be packaged or spread from cell to cell. The second vector (OriLyt-CD) contains the EBV lytic origin of replication (oriLyt), the EBV packaging sequences (located in the viral termini), the oriP enhancer element (but not the complete replication origin), and the EBV BZLF1 gene (which induces expression of the EBV proteins required for replication of oriLyt). The OriLyt-CD vector is replicated through the oriLyt origin specifically in EBV-positive cells and packaged as an EBV pseudovirion. The packaged oriLyt-CD virion can subsequently infect cells containing the EBV receptor, CD21, and initiate another round of replication in EBV-positive cells. Here we demonstrate that each of these two different EBV-based gene therapy strategies induces specific killing of EBV-positive B cells in vitro (in the presence of 5-FC). The advantages and disadvantages of each strategy are discussed.

Linkage analysis of human leukocyte antigen (HLA) markers in familial psoriasis: strong disequilibrium effects provide evidence for a major determinant in the HLA-B/-C region.

Although psoriasis is strongly associated with certain human leukocyte antigens (HLAs), evidence for linkage to HLA markers has been limited. The objectives of this study were (1) to provide more definitive evidence for linkage of psoriasis to HLA markers in multiplex families; (2) to compare the major HLA risk alleles in these families with those determined by previous case-control studies; and (3) to localize the gene more precisely. By applying the transmission/disequilibrium test (TDT) and parametric linkage analysis, we found evidence for linkage of psoriasis to HLA-C, -B, -DR, and -DQ, with HLA-B and -C yielding the most-significant results. Linkage was detectable by parametric methods only when marker-trait disequilibrium was considered. Case-control association tests and the TDT identified alleles belonging to the EH57.1 ancestral haplotype as the major risk alleles in our sample. Among individuals carrying recombinant ancestral haplotypes involving EH57. 1, the class I markers were retained selectively among affecteds four times more often than among unaffecteds; among the few affected individuals carrying only the class II alleles from the ancestral haplotype, all but one also carried Cw6. These data show that familial and "sporadic" psoriasis share the same risk alleles. They also illustrate that substantial parametric linkage information can be extracted by accounting for linkage disequilibrium. Finally, they strongly suggest that a major susceptibility gene resides near HLA-C.

Coupled transcriptional and translational control of cyclin-dependent kinase inhibitor p18INK4c expression during myogenesis.

Terminal differentiation of many cell types involves permanent withdrawal from the cell division cycle. The p18INK4c protein, a member of the p16/INK4 cyclin-dependent kinase (CDK) inhibitor family, is induced more than 50-fold during myogenic differentiation of mouse C2C12 myoblasts to become the predominant CDK inhibitor complexed with CDK4 and CDK6 in terminally differentiated myotubes. We have found that the p18INK4c gene expresses two mRNA transcripts--a 2.4-kb transcript, p18(L), and a 1.2-kb transcript, p18(S). In proliferating C2C12 myoblasts, only the larger p18(L) transcript is expressed from an upstream promoter. As C2C12 cells are induced to differentiate into permanently arrested myotubes, the abundance of the p18(L) transcript decreases. The smaller p18(S) transcript expressed from a downstream promoter becomes detectable by 12 h postinduction and is the predominant transcript expressed in terminally differentiated myotubes. Both transcripts contain coding exons 2 and 3, but p18(L) uniquely contains an additional noncoding 1.2-kb exon, exon 1, corresponding exclusively to the 5' untranslated region (5' UTR). The expression pattern of the shorter p18(S) transcript, but not that of the longer p18(L) transcript, correlates with terminal differentiation of muscle, lung, liver, thymus, and eye lens cells during mouse embryo development. The presence of the long 5' UTR in exon 1 attenuated the translation of p18(L) transcript, while its absence from the shorter p18(S) transcript resulted in significantly more efficient translation of the p18 protein. Our results demonstrate that during terminal muscle cell differentiation, induction of the p18 protein is regulated by promoter switching coupled with translational control.

The major histocompatibility complex and the chemosensory signalling of individuality in humans.

The chemosensory identity of mice and rats is determined partly by polymorphic genes of the major histocompatibility complex (MHC). In inbred strains of mice, as well as in seminatural populations, MHC-associated mating preferences selectively influence reproductive success, thus serving to promote heterozygocity in the MHC. In order to determine whether MHC-associated chemosignals are present in humans, two studies were conducted. In a first study, olfactory identification of MHC-associated chemosignals was conducted on 12 trained rats' responses to the urine odors of humans. In a second study, MHC-associated olfactory cues in humans were analyzed by means of gas chromatography. The results indicate that the urine odors of humans are associated with the MHC and demonstrate that the profile of volatile components in the urine odors shows some association with the MHC. Furthermore, results show that a profile of some specific components, as well as a few ubiquitous volatiles, constitutes MHC-associated odor signals in humans.