Synthetic CD4 exocyclics inhibit binding of human immunodeficiency virus type 1 envelope to CD4 and virus replication in T lymphocytes

CD4 functions as a major T-cell surface receptor for human immunodeficiency virus by binding the human immunodeficiency virus type 1 (HIV-1) envelope protein gp120 with relatively high affinity. We have developed constrained aromatically modified analogs of the secondary structures of the first domain of CD4 in order to analyze surfaces involved in binding of gp120. Complementarity determining-like regions (CDRs) of the D1 domain of CD4 were reproduced as synthetic aromatically modified exocyclic (AMEs) forms. The exocyclic CDR3.AME(82-89), derived from the CDR3 (residues 82-89) region of CD4 D1 domain, specifically inhibited binding of recombinant gp120 to both recombinant soluble CD4, and CD4+ Jurkat cells, and blocked syncytium formation and virus particle production caused by HIV-1 infection. We have previously shown that the CDR3.AME analog binds to the CD4 CDR3 region and creates a disabled CD4 heterodimer. We propose that the AME prevents the formation of an essential homodimeric surface needed for efficient HIV binding. Additionally the disabled CD4 receptor may be less able to signal the cell to allow HIV replication and HIV infection. Such compounds may represent a new receptor specific approach to modulate biological functions.

In vitro and in vivo tumor growth suppression by HIV-1 Vpr

We have previously reported that the human immunodeficiency virus type 1 (HIV-1) regulatory gene vpr induces differentiation of rhabdomyosarcoma (embryonal muscle tumor cell line) cells, an effect that is accompanied by reduced proliferative capacity of the transfected cells. In this report, we examine the effect of Vpr expression on several different tumor cell lines derived from unique lineages. These tumor cells display different patterns of modulated oncogenes including both ras and p53 mutations. Here we demonstrate that the growth of tumor cells in vitro and in vivo is arrested by the expression of HIV-1 Vpr. Expression of Vpr in several human tumor cell lines upon transfection resulted in an accumulation of cells in the G2/M phase of cell cycle with altered cellular morphology, including an increase in adherence, and growth arrest, consistent with a differentiated phenotype. Vpr expression in B78/H1 cells results in a marked reduction in colony formation in vitro and an associated reduction in melanin synthesis by the cells. Vpr-transfected melanoma cells inoculated into syngenic C57BL/6 mice showed a markedly reduced ability to form tumors in vivo. These results suggest that this retroviral regulatory gene has broad tumor suppressor effects, likely mediated by transcriptional regulation of the state of the host cell.

Safety and immunogenicity of intramuscular and intravaginal delivery of HIV-1 DNA constructs to infant chimpanzees

Any global strategy for controlling the human immunodeficiency virus (HIV) epidemic is likely to rely heavily on immunization of infants and children. Given the well-documented differences in children's responses to traditional vaccines, we initiated this study to extend our findings on DNA vaccination of adult chimpanzees to immunologically immature infant chimpanzees. Our findings were consistent with our previous work in adults as we observed that the DNA vaccines used here were both well tolerated and immunogenic within weeks of the initial vaccination.

In vivo engineering of a cellular immune response by coadministration of IL-12 expression vector with a DNA immunogen

Recent studies support the importance of investigating a DNA vaccination approach for the immunologic control of HIV-1. In this regard, it may be important to specifically engineer immune responses in order to improve on first generation vaccine attempts. Especially for HIV, induction of cell-mediated immunity may be an important feature for any candidate vaccine. In an attempt to engineer in vivo the enhancement of cellular immune response and to direct Ag-dependent immune response from Th2 to Th1 type, we investigated the role of codelivery of genes for IL-12 and granulocyte-macrophage-CSF along with DNA vaccine formulations for HIV-1 Ag. We found that codelivery of IL-12 expression cassettes with DNA vaccines for HIV-1 in mice resulted in splenomegaly as well as a shift in the specific immune responses induced. The codelivery of IL-12 genes resulted in the reduction of specific Ab response, while the coinjection of granulocyte-macrophage-CSF genes resulted in the enhancement of specific Ab response. In addition, we observed a significant Ag-specific stimulation of T cells with codelivery of both cytokines. Most importantly, we observed a dramatic increase in specific CTL response from the group coimmunized with the HIV-1 DNA vaccine and IL-12 genes. This work demonstrates the power of DNA delivery in vivo for both the production of a new generation of more effective and targeted vaccines or immunotherapies as well as an analytic tool for the molecular dissection of the mechanisms of immune function.

In vivo engineering of a cellular immune response by coadministration of IL-12 expression vector with a DNA immunogen

Recent studies support the importance of investigating a DNA vaccination approach for the immunologic control of HIV-1. In this regard, it may be important to specifically engineer immune responses in order to improve on first generation vaccine attempts. Especially for HIV, induction of cell-mediated immunity may be an important feature for any candidate vaccine. In an attempt to engineer in vivo the enhancement of cellular immune response and to direct Ag-dependent immune response from Th2 to Th1 type, we investigated the role of codelivery of genes for IL-12 and granulocyte-macrophage-CSF along with DNA vaccine formulations for HIV-1 Ag. We found that codelivery of IL-12 expression cassettes with DNA vaccines for HIV-1 in mice resulted in splenomegaly as well as a shift in the specific immune responses induced. The codelivery of IL-12 genes resulted in the reduction of specific Ab response, while the coinjection of granulocyte-macrophage-CSF genes resulted in the enhancement of specific Ab response. In addition, we observed a significant Ag-specific stimulation of T cells with codelivery of both cytokines. Most importantly, we observed a dramatic increase in specific CTL response from the group coimmunized with the HIV-1 DNA vaccine and IL-12 genes. This work demonstrates the power of DNA delivery in vivo for both the production of a new generation of more effective and targeted vaccines or immunotherapies as well as an analytic tool for the molecular dissection of the mechanisms of immune function.

HIV-1 viral protein R (Vpr) as a regulator of the target cell

Among the putative 'accessory genes' of HIV-1, the 96 amino acid virion-associated Vpr gene product has been described to have several novel biological activities. These include cytoplasmic-to-nuclear translocation thus empowering HIV to infect and replicate in nondividing cells and to function to increase viral replication, particularly in monocytes. Along with these viral effects, we describe the dramatic biological changes induced by HIV-1 Vpr in the target cells of HIV infection including induction of changes in transcriptional patterns and complete inhibition of proliferation which collectively is termed differentiation. These changes occur in the absence of other viral gene products and suggest that Vpr mediates its proviral effects partially or perhaps solely through modulation of the state of the target cell rather than directly on the virus. The inhibition of proliferation in T-cell lines has been proposed by several groups to demonstrate that the inhibition of proliferation specifically arrests the cell cycle further supporting the notion that Vpr activity is directed at cellular targets. We have recently described a role for Vpr in modulating the glucocorticoid pathway, a pathway involved in the regulation of the state of the cell in cytoplasmic-to-nuclear translocation and in the modulation of host cell transcription. Importantly, certain antiglucocorticoids have been shown to modulate Vpr activity in vitro. These results demonstrate that the cell contains specific receptor(s) molecule(s) through which Vpr mediates its activity and that these molecules have implications for cell biology in general. These results collectively demonstrate that Vpr represents a unique target for anti-HIV drug development and has significance for HIV-1 disease progression.

Vertical transmission of human immunodeficiency virus type 1: seroreactivity by maternal antibodies to the carboxy region of the gp41 envelope glycoprotein

Maternal antibodies against the envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1) have previously been suggested to be important in influencing the rate of vertical transmission. In this study, serum antibody responses in mothers who did or did not transmit HIV-1 infection to their children were measured against the carboxy region of the transmembrane envelope glycoprotein gp41. Results indicate significantly higher binding reactivity of nontransmitter mothers compared with transmitters to three peptides spanning amino acids 771-810 and 841-856. In addition, high neutralization titers in maternal sera against HIV-1(MN) were associated with a nontransmission status. This is the initial report demonstrating a correlation between maternal antibody binding to epitopes within the carboxy region of gp41 envelope glycoprotein and lack of vertical transmission. Immunodetection that identifies antibodies to these regions in gp41 could therefore be considered a strategy to assess the risk of vertical transmission of HIV-1.

Interferon-gamma receptor-deficiency renders mice highly susceptible to toxoplasmosis by decreased macrophage activation

Toxoplasma gondii may cause severe infections in immunocompromised patients including fetuses and those with AIDS. Among the factors mediating protection against T. gondii, IFN-gamma has gained special attention. To analyze the role of IFN-gamma in the early phase of toxoplasmosis, IFN-gamma receptor-deficient (IFN-gamma R0/0) mice were orally infected with low-virulent toxoplasms. IFN-gamma R0/0 mice died of the disease up to day 10 postinfection, whereas immunocompetent wild-type (WT) mice developed a chronic toxoplasmosis. Histopathology revealed that in IFN-gamma R0/0 mice, the parasite multiplied unrestrictedly in the small intestine, the intestinal lymphatic tissue, the liver, and the spleen. Ultimately, animals died of a necrotizing hepatitis. In WT mice, the same organs were effected, but multiplication of the parasite was effectively limited. Compared with WT mice, immunohistochemistry and flow cytometry demonstrated that in IFN-gamma R0/0 mice, macrophages were only marginally activated in response to the infection, as evidenced by a reduced expression of major histocompatability complex class II antigens. In addition, immunohistochemistry and RT-PCR showed a reduced production of the macrophage-derived cytokines tumor necrosis factor-alpha, inducible nitric oxide synthase, and IL-1 beta in the liver of IFN-gamma R0/0 mice. In contrast, activation of T cells, recruitment of immune cells to inflammatory foci, and anti-T. gondii IgM antibody production were unaffected by the mutation of the IFN-gamma R. Moreover, induction of IL-2, IL-4, and IL-10 mRNA transcripts in the liver was normal in IFN-gamma R0/0 mice. Adoptive transfer experiments revealed that the immune T cells of WT animals did not protect IFN-gamma R0/0 mice from lethal infection with highly virulent toxoplasms, whereas WT mice were significantly protected by the adoptive transfer. Based on these studies, we conclude that IFN-gamma is absolutely required for an efficient activation of macrophages. Macrophages are of critical importance in toxoplasmosis, and insufficient macrophage activation cannot be compensated by other immune mechanisms.

Rational design, analysis, and potential utility of GM-CSF antagonists

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is an important cytokine involved in many immune and inflammatory processes and is believed to act in the early stages of immune responses. GM-CSF stimulates antigen-presenting cells, enhancing antigen presentation and inducing macrophage tumoricidal activity. GM-CSF binds to specific cellular receptors that are potential targets for pharmacological design. Rational design of small-molecule mimics is an important approach to pharmacophore design. One of the strategies in the development of small-molecular mimics of larger polypeptyde ligands is analysis of alternative ligands that bind the same site as does the native ligand. Molecular studies of GM-CSF-receptor interactions have led to the development of interaction site analogs and the development of an "anti-anti-GM-CSF" recombinant antibody (rAb) analog of a site on GM-CSF important for biological activity and receptor binding. This rAb and a peptide derived from the rAb first complementarity determining region (CDR) sequence bind to a monoclonal anti-GM-CSF antibody that mimics the GM-CSFR alpha chain, compete with GM-CSF for binding to GM-CSF receptor alpha chain (GM-CSFR alpha), and are specific biological antagonists. Molecular modeling of the rAb suggests structural similarity with a site previously implicated in GM-CSF binding to the GM-CSFR alpha. Two cyclic peptides, 1785 and 1786, also were developed on the basis of structural analysis of the GM-CSF region mimicked by anti-anti-GM-CSF recombinant antibody (rAb) 23.2. These peptides were designed to mimic structurally the positions of specific residues on the B and C helicies of human GM-CSF implicated in receptor binding and bioactivity. Both 1785 and 1786 were recognized specifically by polyclonal anti-GM-CSF antibody. 1786 also competitively inhibited binding of GM-CSF to the GM-CSF receptor and demonstrated antagonist bioactivity, as shown by its reversal of GM-CSF's ability to inhibit apoptosis of the GM-CSF-dependent cell line MO7E. These studies support the role of residues on the GM-CSF B and C helicies in receptor binding and bioactivity and suggest strategies for mimicking binding sites on four-helix bundle proteins with cyclic peptides.

Pain measurement in elders with chronic low back pain: traditional and alternative approaches

Pain evaluation typically relies upon the use of self-report instruments. The validity of these tools is questionable in many older adults, however, particularly those with cognitive impairment. Rating of pain behavior (e.g. grimacing, sighing) by an objective observer represents an alternative pain assessment strategy which has been validated in subjects of heterogeneous ages. The purpose of this study was to examine, in a group of community-dwelling elderly with low back pain and lumbosacral osteoarthritis, the concurrent validity of observational pain behavior rating techniques as compared with self-report instruments and the degree to which pain and pain behavior relate to disability. Thirty-nine cognitively intact subjects, age > 65 years, without depression, other sources of pain, or other known spinal pathology underwent the following measures: (1) pain self-report using the verbal 0-10 scale, vertical verbal descriptor scale, Arthritis Impact Measurement Scales and McGill Pain Questionnaire; (2) pain behavior was sampled during two protocols, one, identical to that used by Keefe and Block (Behav. Ther., 13 (1982) 363-375), that required subjects to sit, stand, walk, and recline for 1-2 minute periods (which we have labelled the traditional protocol), and a second, more demanding protocol that was designed to simulate activities of daily living that place a premium on axial movement (the 'ADL' protocol); (3) disability was assessed using the Roland questionnaire, a 6 month global disability question and the Jette Functional Status Index; and (4) radiographic evaluation of the lumbosacral spine; osteoarthritis was quantitated using a previously validated scoring system. Interrelationships among pain, pain behavior and disability measures were tested using canonical correlations. Self-reported pain was associated with pain behavior frequency; the association was stronger when the ADL protocol was used, as compared with the traditional protocol. The association between pain and disability was modestly strong with both self-report instruments and pain behavior observation when the ADL protocol was used, but not when the traditional protocol was used. Our findings suggest that pain behavior observation is a valid assessment tool in the elderly. In addition, it seems that observation of elders during performance of activities of daily living may be a more sensitive and valid way of assessing pain behavior than observing pain behavior during sitting, walking, standing, or reclining.

Expression and immune response to hepatitis C virus core DNA-based vaccine constructs

Hepatitis C virus (HCV) is a major worldwide cause of acute and chronic hepatitis, cirrhosis, and hepatocellular carcinoma. The development of vaccines against HCV have been complicated by the high variability of the envelope region, and it is likely that the cellular immune responses to viral structural proteins may be important for eradicating persistent viral infection. Recently, it was reported that the injection into muscle cells of plasmids encoding viral genes resulted in the generation of strong cellular immune responses. We constructed vectors that express the highly conserved HCV core gene. In this regard, the pHCV 2-2 construct contained the entire HCV core region and pHCV 4-2 contained both the 5' noncoding region and the core gene. Cellular expression of HCV core protein was assessed following transfection into human and murine cell lines, and higher intracellular levels of the 21-kd core protein were observed with pHCV 2-2. These HCV core DNA constructs were used to immunize BALB/c mice and produced low-level anti-HCV core humoral immune responses. To assess cytotoxic T-lymphocyte (CTL) activity generated in vivo, a cloned syngeneic SP2/O myeloma cell line constitutively expressing HCV core protein was established and inoculated into BALB/c mice to produce growth of plasmacytomas. Strong CTL activity was generated because the tumor size and weight in pHCV 2-2-immunized mice were remarkably reduced compared with mice injected with mock DNA. Spontaneous CTL activity was also exhibited by splenocytes in an in vitro cytotoxicity assay. These investigations demonstrate that plasmid constructs expressing HCV core protein generate strong CTL activity, as assessed both in vivo and in vitro, and are promising candidates as antiviral agents.

Expression and immune response to hepatitis C virus core DNA-based vaccine constructs

Hepatitis C virus (HCV) is a major worldwide cause of acute and chronic hepatitis, cirrhosis, and hepatocellular carcinoma. The development of vaccines against HCV have been complicated by the high variability of the envelope region, and it is likely that the cellular immune responses to viral structural proteins may be important for eradicating persistent viral infection. Recently, it was reported that the injection into muscle cells of plasmids encoding viral genes resulted in the generation of strong cellular immune responses. We constructed vectors that express the highly conserved HCV core gene. In this regard, the pHCV 2-2 construct contained the entire HCV core region and pHCV 4-2 contained both the 5' noncoding region and the core gene. Cellular expression of HCV core protein was assessed following transfection into human and murine cell lines, and higher intracellular levels of the 21-kd core protein were observed with pHCV 2-2. These HCV core DNA constructs were used to immunize BALB/c mice and produced low-level anti-HCV core humoral immune responses. To assess cytotoxic T-lymphocyte (CTL) activity generated in vivo, a cloned syngeneic SP2/O myeloma cell line constitutively expressing HCV core protein was established and inoculated into BALB/c mice to produce growth of plasmacytomas. Strong CTL activity was generated because the tumor size and weight in pHCV 2-2-immunized mice were remarkably reduced compared with mice injected with mock DNA. Spontaneous CTL activity was also exhibited by splenocytes in an in vitro cytotoxicity assay. These investigations demonstrate that plasmid constructs expressing HCV core protein generate strong CTL activity, as assessed both in vivo and in vitro, and are promising candidates as antiviral agents.

A human monoclonal antibody to HIV-1 gp41 with neutralizing activity against diverse laboratory isolates

A potential component that may be useful for passive immunotherapy for HIV-1 is human monoclonal antibodies (HumAbs) possessing potent anti-HIV-1 activity that is directed against conserved regions of the envelope glycoprotein. Such antibodies would, in principle, have the ability to neutralize diverse isolates of HIV-1. To develop such reagents, hybridomas were derived by initial Epstein Barr virus transformation of peripheral blood mononuclear cells (PBMCs) from an asymptomatic HIV-1 seropositive donor followed by fusion with heteromyelomas, and secreted anti-HIV-1 antibodies were further characterized. The specificity of one HumAb, designated as clone 3, was determined by enzyme-linked immunosorbent assay (ELISA) and Western blotting analyses that indicated reactivity to the transmembrane envelope glyco-protein gp41. Synthetic pentadecapeptides overlapping by 10 amino acids were utilized for epitope mapping of clone 3; a decapeptide GCSGKLICTT in the transmembrane gp41 was identified as the epitope. Clone 3 bound to SupT1 cells infected with HTLV-IIIB in fluorescent activated cell sorting analysis. In addition, in vitro biological assays demonstrated that clone 3 possessed neutralization reactivity against diverse laboratory isolates as well as an AZT-resistant isolate. Therefore, clone 3 reactivity defines a conserved neutralizable site on the HIV-1 transmembrane glycoprotein. Clone 3 and the conserved immunogenic epitope on gp41 could be useful in passive and active immunotherapy for the acquired immunodeficiency syndrome (AIDS).

Analysis of genetic heterogeneity, antigenicity, and biological characteristics of HIV-1 in a maternal transmitter and nontransmitter patient pair

To obtain insight into the factors involved in vertical transmission, we compared the sequence diversity, seroreactivity, and biological characteristics of human immunodeficiency virus type 1 (HIV-1) derived from a transmitter and nontransmitter mother pair. Forty-two clones from the transmitter and 20 from the nontransmitter, spanning the principal neutralization determinant (PND) of the env gene, were sequenced and analyzed. The intrapatient sequence variation in transmitter and nontransmitter viruses was 12% and 36%, respectively, and the interpatient variation was 38%. In an effort to correlate immune responses to viral genetics, we analyzed the sera from these patients against a number of V3 peptides from known HIV-1 isolates. We observed that (i) both the transmitter and nontransmitter sera demonstrated higher binding to V3 peptides based on SF-2 and MN sequences than to IIIB and Z6 isolates; (ii) the vertical transmission of HIV-1 is correlated with the absence of high maternal antibody responses to the PND; and (iii) the high-affinity binding of the sera to SF-2 and MN V3 peptides correlated with the sequence analysis, indicating that the V3 sequences from both patients are more closely related to ADA, SF-162, and MN than to IIIB or Z6. Biological analysis of the viruses from these patients demonstrate that the transmitters' viruses infect a number of T-cell lines in vitro, whereas the nontransmitter viruses do not infect cell lines or the primary lymphocytes.

Molecular detection of bacterial DNA in venereal-associated arthritis

OBJECTIVE

To evaluate the utility of polymerase chain reaction (PCR) amplification in detecting DNA from venereal-associated microorganisms in the synovial fluid of patients with inflammatory arthritis.

METHODS

Oligonucleotide primers were developed for nested PCR based on Chlamydia, Ureaplasma, and Neisseria DNA sequences. PCR products were detected by gel electrophoresis and dot-blot hybridization. Primers specific for the target bacterial DNA were used to search for bacterial DNA in 61 synovial fluid specimens from patients with inflammatory arthritis, including several clinically associated with venereal infection.

RESULTS

Five of the 61 synovial fluid specimens were positive for Neisseria gonorrhoeae DNA. Four of the 5 patients had clinical diagnoses of gonococcal arthritis; the other patient had an unexplained monarthritis. One specimen from a patient with a clinical diagnosis of gonococcal arthritis was negative for N gonorrhoeae. Three of the 61 specimens were positive for Chlamydia DNA. Two were derived from patients with clinical diagnoses of reactive arthritis or Reiter's syndrome, and 1 was from a patient with unexplained monarthritis. One of the 61 specimens was positive from Ureaplasma DNA; this sample was from a patient with a clinical diagnosis of Reiter's syndrome. In an additional patient with Reiter's syndrome, Ureaplasma DNA was also found in prostate biopsy tissue and a urine sample obtained after prostate massage (synovial fluid not available).

CONCLUSION

These data support the classification of these 3 venereal-associated arthritides as infectious processes, and suggest that PCR for bacterial DNA is a useful method for detecting infectious agents in synovial fluid.

In vivo protective anti-HIV immune responses in non-human primates through DNA immunization

An effective immune response involves the specific recognition of and elimination of an infectious organism at multiple levels. In this context DNA immunization can present functional antigenic proteins to the host for recognition by all arms of the immune system, yet provides the opportunity to delete any genes of the infectious organism which code for antigens or pieces of antigens that may have deleterious effects. Our group has developed the use of nucleic acid immunization as a possible method of vaccination against Human immunodeficiency virus type 1 (HIV-1) [1,2,3,10,11,12]. Sera from non-human primates immunized with DNA vectors that express the envelope proteins from HIV-1 contain antibodies specific to the HIV-1 envelope. These sera also neutralize HIV-1 infection in vitro and inhibit cell to cell infection in tissue culture. Analysis of cellular responses is equally encouraging. T cell proliferation as well as cytotoxic T cell lysis of relevant env expressing target cells were observed. In addition, evidence that DNA vaccines are capable of inducing a protective response against live virus was demonstrated using a chimeric SIV/HIV (SHIV) challenge in vaccinated cynomologous macaques. We found that nucleic acid vaccination induced protection from challenge in one out of four immunized cynomolgus macaques and viral load was lower in the vaccinated group of animals versus the control group of animals. These data encouraged us to analyze this vaccination technique in chimpanzees, the most closely related animal species to man. We observed the induction of both cellular and humoral immune responses with a DNA vaccine in chimpanzees. These studies demonstrate the utility of this technology to induce relevant immune responses in primates which may ultimately lead to effective vaccines.

Rational design of granulocyte-macrophage colony-stimulating factor antagonist peptides

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a member of the four-helix bundle family of cytokines/growth factors which exhibit several activities. It is a hematopoietic growth factor, a cytokine involved in inflammatory and immune processes, an adjunct for cancer therapy, and an anti-tumor immunomodulator. Studies of interactions between GM-CSF and its receptor and identification of small peptides presenting binding capacity to the receptor are important goals for the development of GM-CSF analogs. Here we describe the study of two cyclic peptides, 1785 and 1786, developed based on structural analysis of the GM-CSF region mimicked by anti-anti-GM-CSF recombinant antibody 23.2. These peptides were designed to structurally mimic the positions of specific residues on the B and C helices of human GM-CSF implicated in receptor binding and bioactivity. Both 1785 and 1786 were specifically recognized by polyclonal anti-GM-CSF antibody (stronger for 1786 than 1785). 1786 also competitively inhibited binding of GM-CSF to the GM-CSF receptor on HL-60 cells and demonstrated antagonist bioactivity, as shown by its reversal of GM-CSF's ability to inhibit apoptosis of the GM-CSF-dependent cell line MO7E. These studies support the role of residues on the GM-CSF B and C helices in receptor binding and bioactivity and suggest strategies for mimicking binding sites on four-helix bundle proteins with cyclic peptides.

Pathogenesis of slipped capital femoral epiphysis: current concepts

Since Ambrose Paré in 1572 initially described what is believed to be the first case of slipped capital femoral epiphysis (SCFE), a virtual plethora of unproven theories has evolved in the ensuing years. The most currently popular theories embrace a framework of biomechanical events versus biochemical events having impact at the time of puberty. The zone of slipping always occurs primarily through the zone of hypertrophy in a corrugated undulating fashion. All investigative studies show that the growth plate at the time of puberty is weakened in SCFE. The final common pathway appears to be a mechanical failure of the growth plate, due to a weakened state, to resist displacement. The commonly encountered large body mass coupled with an increasingly oblique physis lying in a relative degree of retroversion creates a mechanical environment that, coupled with delicate alterations in the hormonal balance of thyroid hormone, growth hormone, testosterone, and estrogen, render the plate intrinsically suspectible to displacement by rather innocuous forces occurring in a shear plane. Ultrastructure studies of SCFE demonstrate a significant alteration in anatomy and physiology in all active metabolic areas of the growth plate. It is the author's concept that SCFE is a generalized metabolic disorder of puberty resulting from a series of pubertal mishaps with a multifactorial basis ordinarily caused by a relative imbalance of hormones, coupled with biomechanical events.

Systemic immunization induces protective CD4+ and CD8+ T cell-mediated immune responses in murine Listeria monocytogenes meningoencephalitis

The immune mechanisms underlying immunization-induced protection of mice from lethal central nervous system (CNS) listeriosis were evaluated by immunohistochemistry, flow cytometry of leukocytes isolated from the brain, reverse transcription-polymerase chain reaction analysis of intracerebral (i.c.) tumor-necrosis factor-alpha, interferon-gamma, interleukin (IL)-2, IL-1 beta, IL-10, granulocyte/macrophage colony-stimulating factor, and inducible nitric oxide synthase mRNA expression, and T cell depletion experiments. The data demonstrate that active immunization of mice prior to an i.c. infection with Listeria monocytogenes prevents the development of a fatal necrotizing encephalitis and accelerates the recruitment of an increased number of alpha beta T cell receptor (TcR)+ CD4+ and CD8+ T cells, gamma delta TcR+ T cells, B cells, granulocytes and macrophages to the brain compared to non-immunized animals. In addition, immunization induced a pronounced activation of i.c. macrophages and microglial cells as shown by an increased expression of MHC class II antigens. In parallel, transcript levels for all cytokine mRNA analyzed were higher in the brains of immunized mice. The protective effects of immunization were completely abolished by depletion of CD4+, CD8+, or both T cell subsets. All groups of T cell-depleted immunized mice developed a fatal necrotizing encephalitis with an increased i.c. bacterial load. In addition, cytokine mRNA synthesis was significantly impaired. The severity of disease was only slightly different between CD4+, CD8+ and CD4+/CD8+ T cell depleted mice, indicating that both subsets of T cells are required for an effective i.c. immune response to L. monocytogenes. This is in marked contrast to systemic listeriosis, and points to CNS-specific features of the immune response.

The glucocorticoid receptor type II complex is a target of the HIV-1 vpr gene product

The vpr gene of human immunodeficiency virus type 1 (HIV-1) encodes a 15-kDa virion-associated protein that functions as a regulator of cellular processes linked to the HIV life cycle. We report the interaction of a 41-kDa cytosolic viral protein R interacting protein 1 (Rip-1) with Vpr in vitro. Rip-1 displays a wide tissue distribution, including relevant targets of HIV infection. Vpr protein induced nuclear translocation of Rip-1, as did glucocorticoid receptor (GR)-II-stimulating steroids. Importantly, Vpr and Rip-1 coimmunoprecipitated with the human GR as part of an activated receptor complex. Vpr complementation of a vpr mutant virus was also mimicked by GR-II-stimulating steroids. Vpr and GR-II actions were inhibited by mifepristone, a GR-II pathway inhibitor. Together these data directly link the activity of the vpr gene product to the glucocorticoid steroid pathway and provide a biochemical mechanism for the cellular and viral activity of Vpr, as well as suggest that a unique class of antivirals, which includes mifepristone (RU486), may influence HIV-1 replication.

Immunization by direct DNA inoculation induces rejection of tumor cell challenge

Direct DNA inoculation is the basis for a new technology that has been successfully used for in vivo induction of both humoral and cellular immune responses. However, the immunological parameters of this new approach remain to be evaluated in detail. We report here that direct DNA inoculation can induce protection from malignant tumor cell challenge through the generation of specific immune responses directed against antigens displayed on the tumor cells. The protected mice remain tumor-free for more than 1 year post-challenge. Memory responses upon tumor rechallenge were observed for both humoral and cellular immunity. Inoculated animals were able to reject otherwise lethal tumors several months following the original DNA inoculation protocol. These in vivo protective responses suggest that further analysis of this technology for vaccine development or immune therapeutic strategies is warranted.