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The management of fractures in children is complex compared to that of adults because of greater elasticity of bone, presence of tooth buds, faster healing rate, potential for future growth and lesser co-operative ability. Fractures of the mandible in children are conventionally treated by circummandibular wiring. This paper reports a variation in the technique of using circummandibular wiring with acrylic splints in the conservative treatment of mandibular fractures in two pediatric patients.

We examined the renal pathology and viral genetic changes following inoculation of six rhesus macaques with lymphocyte-tropic SIVmac239. Portions of the renal cortex were sieved into glomerular and tubulointerstitial (TI) fractions and examined for SIVmac sequences by PCR and for p27 core antigen. SIVmac sequences were detected in renal tissue from five of six macaques (three of five glomerular and five of five TI fractions were positive for SIV by PCR). Glomerulosclerosis (segmental and global) was evident in two macaques that were positive for env sequences in the glomerular fractions. Diffuse mesangial hyperplasia and matrix expansion were present in all three animals with glomerular SIV, as was an increase in glomerular collagen I and collagen IV. Tubulointerstitial inflammation was evident in all virus-inoculated macaques. The TI infiltration of CD68+ cells was most pronounced in the animals with SIVmac present in the glomerulus. All SIVmac-infected macaques exhibited increased glomerular deposition of IgM and to a lesser extent IgG, but no C3 or IgA was evident. Sequence analyses of the viral env gene (gp120) isolated from the glomerular and TI fractions of a macaque that developed glomerulopathy revealed the presence of specific viral variants in glomerular and TI fractions. In addition, chimeric viruses constructed with glomerular but not tubulointerstitial gp120 sequences were converted to a macrophage-tropic phenotype. These results indicate that infection by lymphocyte-tropic SIVmac239 is primarily associated with immunoglobulin deposition in the glomerulus and suggests that when glomerulosclerosis develops there is selection of viral variants that are macrophage tropic in nature.

By subcutaneous inoculation of SHIV(KU-2) in the hands of macaques, we developed a model of human immunodeficiency virus type-1 (HIV-1) occupational infection due to needle-stick injury and used the model to determine whether neutralizing serum to SHIV administered before or after virus inoculation could either prevent or abort infection, respectively. Six rhesus macaques were given 15 ml/kg pooled anti-SHIV plasma and challenged 24 hr later with approximately 300 animal infectious doses of SHIV(KU-2), subcutaneously. Three of the six macaques completely resisted infection with SHIV(KU-2). A fourth animal failed to yield infectious virus, but DNA extracted from its peripheral blood mononuclear cells (PBMC) and lymph nodes had viral sequences. Partial resistance was noted in the other two animals because virus recovery was delayed compared with the control animals. In contrast, six of six macaques given the same dose of anti-SHIV plasma 18 hr after exposure to virus became infected, as did two of two macaques given anti-SHIV plasma only 2 hr after exposure to virus. Our results suggest that neutralizing antibodies may have a prophylactic but not a therapeutic role in HIV-1 infections.

We recently reported that a chimeric simian/human immunodeficiency virus (SHIV(KU‐1)) developed in our laboratory caused progressive depletion of CD4(+)T lymphocytes and AIDS within 6 months of inoculation into pig‐tailed macaques (M.nemestrina). None of the pig‐tailed macaques showed productive SHIV infection in the central nervous system (CNS). In this report, we show that by further passage of the pathogenic virus in rhesus macaques [M. mulatta], we have derived a new strain of SHIV (SHIV(KU‐2)) that has caused AIDS and productive CNS infection in 3 of 5 rhesus macaques infected with the virus. Productive replication of SHIV in the CNS was clearly shown by high infectivity titers and p27 protein levels in brain homogenates, and in 2 of the 3 rhesus macaques this was associated with disseminated, nodular, demyelinating lesions, including focal multinucleated giant cell reaction, largely confined to the white matter. These findings were reminiscent of HIV‐1 associated neurological disease, and our immunohistochemical and in situ hybridization data indicated that the neuropathological lesions were associated with the presence of SHIV‐specific viral antigens and nucleic acid respectively. However, the concomitant reactivation of opportunistic infections in these macaques suggested that such pathogens may have influenced the replication of SHIV in the CNS, or modified the neuropathological sequelae of SHIV infection in the rhesus species, but not in pig‐tailed macaques. Our findings in the two species of macaques highlight the complexities of lentiviral neuropathogenesis, the precise mechanisms of which are still elusive.

Recent studies have identified the presence of a novel Mep/Amt/Rh glycoprotein family of proteins that may play an important role in transmembrane ammonia transport. One of the mammalian members of this family, Rh C glycoprotein (RhCG), transports ammonia, is expressed in distal nephron sites that are critically important for ammonia secretion, exhibits increased expression in response to chronic metabolic acidosis, and originally was cloned as a tumor-related protein. The purpose of our studies was to determine the localization of RhCG in the normal and neoplastic human kidney. Immunoblot analysis of human renal cortical protein lysates demonstrated RhCG protein expression with a molecular weight of approximately 52 kD. Immunohistochemistry revealed both apical and basolateral Rhcg expression in the distal convoluted tubule, connecting segment, and initial collecting tubule and throughout the collecting duct. Co-localization with calbindin-D28k, H + -ATPase, aquaporin-2, and pendrin showed that distal convoluted tubule and connecting segment cells, A-type intercalated cells, and non-A, non-B cells express RhCG and that B-type intercalated cells, principal cells, and inner medullary collecting duct cells do not. In renal neoplasms, RhCG was expressed by chromophobe renal cell carcinoma and renal oncocytoma but not by clear cell renal cell carcinoma or by papillary renal cell carcinomas. These studies suggest that RhCG contributes to both apical and basolateral membrane ammonia transport in the human kidney. Furthermore, renal chromophobe renal cell carcinoma and renal oncocytoma seem to originate from the A-type intercalated cell.

The question of whether consensus nucleotide substitutions in the long terminal repeat (LTR) region of simian immunodeficiency virus strain mac (SIVmac) are important for neurovirulence was investigated in this report. Brains and lymph nodes from two macaques that developed AIDS and encephalitis following inoculation with two strains of neurovirulent SIVmac, and from one animal with AIDS but no neurological disease after inoculation with non-neurovirulent SIVmac239 were used. The 5' LTR regions from neurovirulent SIVmacR71/17E and SIVmac7F-Lu were amplified, cloned and sequenced and these sequences were compared to the LTRs amplified from three regions of the respective encephalitic brains and lymph nodes from macaques inoculated with each virus. The SIVmac7F-Lu and SIVmacR71/17E viruses had zero and three consensus substitutions, respectively, in the U3, R and U5 regions of the LTR compared to that of SIVmac239. The only consensus substitution in the LTR-gag region of the genome was a T to C change at position 829 within the tRNA binding site. The sequences amplified from the brain and lymph nodes of the two animals with AIDS and encephalitis were identical. This single common substitution in this region of the virus genome, the T to C substitution at position 829, was also found in the LTRs isolated from the brain and lymphoid organs from the macaque inoculated with SIVmac239. The virtual identity in nucleotide sequences in the LTR of the neurovirulent and non-neurovirulent viruses and in CNS and lymph tissues of animals inoculated with the viruses suggests that the LTR has no effect on the tissue tropisms of the viruses.

Microglia, alveolar macrophages, and Langerhans cells are representatives of cells of macrophage lineage that are susceptible to infection with HIV-1 and they play important roles in the pathogenesis of AIDS dementia, lymphoid interstitial pneumonia, and systemic viral invasion from mucosal surfaces, respectively. In contrast, elimination of CD4+ T cells with resultant development of immunosuppression and AIDS is thought to be reflective of the exclusive tropism of the virus for CD4+ T cells. Examination of these concepts in macaques infected with molecularly cloned strains of SIVmac suggested that all strains of the virus are both macrophage- and lymphocyte-tropic and that all aspects of pathogenesis including loss of CD4+ T cells are dependent on infection in both cell types. However, viral clones that caused productive lytic infection in macrophages were less virulent than those which caused persistent nonproductive infection. The former caused subclinical and even immunizing infections, whereas the latter caused activation and productive infection in CD4+ T cells, AIDS, and systemic infection, even after inoculation of the virus on mucosal surfaces. If these findings on SIVmac are relevant to HIV-1 disease, then demonstration that HIV-1 isolates are macrophage-tropic probably does not necessarily correlate with their pathogenic potential.

We have examined both the sequence changes in the LTR, gag, vif, vpr, vpx, tat, rev, vpu, env, and nef genes and the cell tropism of a cell-free stock of chimeric simian–human immunodeficiency virus (SHIV) isolated from the cerebrospinal fluid of a pig-tailed macaque (PNb) that developed AIDS. This virus (SHIV KU-1 ) is highly pathogenic when inoculated into other macaques. DNA sequence analysis of PCR-amplified products revealed a total of 5 nucleotide changes in the LTR while vif had 2 consensus amino acid changes. The gag, vif, and vpx had no consensus amino acid substitutions, whereas vpr had 1 consensus substitution. The tat and rev genes of the HXB2 region of SHIV KU-1 had 2 and 1 consensus amino acid changes, respectively. The vpu gene of the HXB2 region of SHIV, which originally had an ACG codon at the beginning of the gene, reverted to an initiation ATG codon and in addition contained a consensus amino acid substitution at position 69 of this protein. As expected, the majority of the nucleotide substitutions were found in the env and nef genes. Thirteen and 5 amino acid changes were predicted for the corresponding Env and Nef proteins, respectively. In addition, one-third of the env gene clones isolated from the SHIV KU-1 stock had a 5-amino-acid deletion in the V4 region. Using three independent assays, we determined that the changes in the SHIV KU-1 were associated with an increase in the efficiency of replication in macrophages. The strikingly few consensus changes in the virus suggest that conversion of this virus to one capable of causing AIDS in pig-tailed macaques was associated with relatively few changes in the viral envelope and/or accessory genes. These results will provide the basis for the development of a pathogenic, molecular clone of SHIV capable of causing AIDS in pig-tailed macaques.

Previously, we described the derivation of a pathogenic strain of simian–human immunodeficiency virus (SHIV KU-2 ) consisting of the tat, rev, vpu, and env genes of HIV-1 (strain HXB2) in a genetic background of SIV mac 239 that causes AIDS and productive infection of the CNS in rhesus macaques ( Macca mulatta ) (Raghavan et al., 1997, Brain Pathol. 7, 851–861). We report here on the characterization of a molecular clone of SHIV KU-2 , designated SHIV KU-2MC4 , that caused CD4 + T cell loss as well as neurological and renal disease in macaques. DNA sequence analysis of selected SIV regions of SHIV KU-2MC4 revealed 10 nucleotide changes in the LTR, whereas Gag, Vif, Vpr, Vpx, and Nef had 1, 1, 1, 2, and 13 predicted amino acid substitutions, respectively, compared to SIV mac 239. DNA sequence analysis of HIV-1 derived regions of SHIV KU-2MC4 revealed 2, 1, 2, and 18 predicted amino acid substitutions in the Tat, Rev, Vpu, and Env proteins, respectively, when compared to SHIV-4. Unlike the parental SHIV-4, which is not tropic for macrophages, SHIV KU-2MC4 replicated efficiently in macrophage cultures as determined by p27 assays. However, despite the numerous changes in the Env protein and newly acquired tropism for macrophages, SHIV KU-2MC4 , like the parental SHIV-4, used CXCR4 exclusively as its coreceptor for entry into susceptible cells. Inoculation of SHIV KU-2MC4 into two rhesus macaques resulted in severe infection in which the numbers of circulating CD4 + T cells in the blood declined rapidly by 2 weeks postinoculation and virus producing cells in the peripheral blood mononuclear cells were identified throughout the course of infection. At the time of euthanasia (20 and 22 weeks), both macaques had lost a significant amount of weight and had no circulating CD4 + T cells. In addition, one macaque developed intension tremors and uncoordinated movements. Virological examination of tissues at necropsy revealed active virus replication in both lymphoid and nonlymphoid tissues such as the lung and brain. Histological examination revealed that the induced immunodeficiency was associated with lymphoid depletion of the lymph nodes and spleen, opportunistic infections, lentiviral encephalitis, and severe glomerulosclerosis of the kidney. This molecular clone will serve as the basis for analyzing the molecular determinants through which SHIV KU-2 causes severe CD4 + T cell loss, neurological disease, and SHIV nephropathy in rhesus macaques.

Twenty macaques were used to evaluate the ability of nonpathogenic SIV mac or nonpathogenic chimeric SIV-HIV (SHIV) to induce protection in macaques against superinfection with a pathogenic variant of SHIV (SHIV KU-1 ) originally containing the tat, rev, vpu, and env of HIV-1 (strain HXB2) in a genetic background of SIV mac 239. Specifically, three macaques inoculated with molecularly cloned, macrophage-tropic SIV mac LG1 developed an early systemic infection but recovered with only traces of SIV mac DNA in visceral lymphoid tissues. These animals were then inoculated parenterally with pathogenic SHIV KU-1 . All three animals resisted infection with SHIV KU-1 , as indicated by lack of virus recovery and absence of SHIV-specific env and vpu sequences in the visceral lymphoid tissues and multiple regions in the CNS. We also examined the ability of five macaques that had been inoculated with nonpathogenic SHIV (NP-SHIV) to withstand challenge with the pathogenic SHIV KU-1 . Like the SIV mac LG1-inoculated macaques, these animals also resisted SHIV KU-1 challenge as judged by the inability to recover infectious virus, normal CD4 + T cell counts, and the absence of SHIV KU-1 signature sequences in the lymph node tissue. Thus, eight of eight animals that developed control over primary lentivirus infections had also developed resistance to infection with pathogenic SHIV KU-1 . Three groups of macaques were used as controls for this study. The first group consisted of six macaques inoculated with SHIV KU-1 alone. All animals developed viremia, showed severe loss of CD4 + T cells within 4 weeks, and succumbed to AIDS within 6 months. The second group of three macaques was inoculated first with SHIV KU-1 and inoculated later with uncloned, neurovirulent SIV mac 7F-Lu. A third group of three macaques was inoculated with SIV mac 7F-Lu followed by inoculation with SHIV KU-1 . PCR analyses using oligonucleotide primers specific for the SIV or HIV env revealed that macaques from the last two groups had widespread infection with both SHIV KU-1 and SIV mac , indicating that animals that failed to control productive replication of either SHIV KU-1 or SIV mac 7F-Lu could not resist superinfection with the other virus. These data indicate that sterilizing immunity against the virulent SHIV could be induced in animals that had experienced an immunizing infection. Moreover, the divergence of the envelope glycoprotein of the protective avirulent and virulent challenge virus suggests that a single vaccine could protect against infection with a virus containing a different envelope glycoprotein.