Total Temporomandibular Joint Prosthetic Reconstruction: The Importance of Lateral Pterygoid Muscle Reattachment to Lateral Excursive and Protrusive Mandibular Movement

Severe temporomandibular joint (TMJ) disorders result in structural changes that can significantly and negatively impact the jaw and airway, resulting in pain, difficulty chewing, dietary restrictions, sleep apnea, and other functional changes.¹ For more than 5 decades, alloplastic total TMJ replacement has been used to treat end-stage intra-articular TMJ disorders. Commonly accepted measures of postsurgical success include maximal incisal opening (MIO), pain relief, and dietary and functional improvement.¹Diminished or unimproved lateral and protrusive jaw movement is a commonly accepted consequence of complete TMJ replacement.² Lateral excursive and protrusive function should, however, be considered and reported as an important measure of success after alloplastic TMJ replacement. To achieve such success, surgeons must comprehensively plan the reconstruction and reattach the lateral pterygoid muscle's inferior head (LPM-IH) to the prosthetic TMJ to support normal functional occlusion and mandibular motion.     

Japanese encephalitis virus replication: A procedure for the selective isolation and characterization of viral RNA species

Summary The viral RNA species synthesized in a porcine kidney cell line, PS(Y-15), by Japanese encephalitis virus (JEV) are described. Virus titers on these cells ranged between 10⁶ to 10⁷ p.f.u./ml at the end of 2 to 3 days incubation at 35° C. Actinomycin D (AD) could not be used to unmask JEV RNA synthesis since it inhibited virus replication at concentrations necessary to substantially reduce host cell RNA synthesis. Treatment of cells with 1 g AD/ml and removal prior to infection permitted good JEV replication, and at the same time strongly suppressed synthesis of 28 S and 18 S cellular ribosomal RNA. The problem of separating viral RNA from non-ribosomal RNA that was still being synthesized by AD pretreated cells was resolved by the isolation of the cytoplasmic membrane fraction of infected cells. RNA extracted from the membranes of infected AD pretreated cells and analyzed for sedimentation characteristics on sucrose gradients has four RNA species not found in uninfected cells.They are: (1) 45 S single stranded RNA believed to be the infectious RNA found in the virion; (2) a 27 S RNA single stranded RNA; (3) a 20 S ribonuclease resistant RNA believed to be double stranded and (4) an 8 S RNA species. The RNA species found in JEV infected cells, except for the 8 S form, have been found in group A arboviruses. The procedure described utilizing AD pretreatment of host cells and the separation of the cellular cytoplasmic fraction may well have value for the study of the biosynthetic events involved in the replication of other animal viruses that are inhibited by AD.This work was supported by the Bureau of Medicine and Surgery, Department of the Navy, Project MR 041.05.01-0006B3GJ.The opinions or assertions contained herein are the private ones of the authors and are not to be construed as official or reflecting the views of the Navy Department or the Naval Service at large.Postdoctoral Research Associate, National Research Council, supported by the Bureau of Medicine and Surgery, Department of the Navy.     

Involvement of the Host Cell Nuclear Envelope Membranes in the Replication of Japanese Encephalitis Virus

The distribution of viral ribonucleic acid (RNA) on various cell membrane fractions derived from a porcine kidney cell line infected with Japanese encephalitis virus was investigated. At 40 h postinfection, after virus growth had reached its peak, three viral RNAs, 45S, 27S, and 20S, were associated with the cytoplasmic membranes and intact nuclei. The amount of each RNA associated with the nucleus was two- to fivefold greater than that present with the cytoplasmic membranes. Treatment of washed infected nuclei with 1.0% Triton X-100, which removed the outer nuclear envelope membrane, also removed the viral RNA. When the nucleus was fractionated into nuclear envelope membranes and a large particle fraction which sedimented at 600 x g, nearly all of the viral RNA remained associated with the envelope membranes. The nuclear envelope membranes contained higher viral RNA polymerase activity than the cytoplasmic membranes derived from the same cells. These data suggest that major sites for Japanese encephalitis virus RNA synthesis may be localized on or in very close association with the nuclear envelope membranes.     

Attenuation and immunogenicity of ts mutants of Eastern encephalitis virus for mice.

Preliminary experiments were intiated to test the attenuation for mice of chemically induced temperature-sensitive (Ets) mutants of a virulents strain of Eastern encephalitis (E) virus, and the potential of such mutants as live virus vaccines for mice. The reversion frequencies of eight mutants to temperature insensitivity were measured and the defects in their biosynthesis at the non-permissive temperature were studied. All eight mutants were less virulent for mice, but the extent of avirulence varied with the mutant and route of injection. The mutants selected as potential vaccines protected mice against subsequent challenge at 10 to 21 days by the virulent virus of strain E. Neutralizing antibody activity was detected in almost all the mutant-infected mice after 10 days, and was found in all infected mice at 21 days. Immunization by two doses of virus induced a very high protection against intracerebral challenge by virus strain E.     

A spontaneous temperature sensitive mutant of Japanese encephalitis virus: Preliminary characterization

Summary A spontaneously arising temperature sensitive (ts) mutant of Japanese encephalitis virus (JEV),ts 104, was isolated from chick fibroblast (CF) cell cultures of JEV strain M1/311. Straints 104 was plaque purified and characterized to ascertain its potential as a candidate for a live vaccine. Parameters of its growth, temperature lability, immunogenicity and virulence were examined.Ts 104 has been shown to be a stablets JEV strain, multiplying as well as the parent strain in CF cultures at 35° C, but not multiplying at 39° C. It was avirulent for embryonated chicken eggs incubated at 39° C and of reduced virulence for intracerebrally (i. c.) inoculated mice as measured by LD₅₀ in weanling mice and average day of death in weanling and suckling mice. Intraperitoneal injection of adult mice with either parent orts strain resulted in similar levels of protection against challenge with either strain. The potential ofts 104 as a candidate live JEV vaccine strain is discussed.With 1 FigureDisclaimers: Supported by Naval Medical Research and Development Command, Navy Department, Research Task No. MF 51.524.009.0067. The opinions and statements contained herein are the private ones of the writer and are not to be construed as official or reflecting the views of the Navy Department or the naval service at large.The animals used in this study were handled in accordance with the provisions of Public Law 89–44 as amended by Public Law 91–579, the Animal Welfare Act of 1970 and the principles outlined in the Guide for the Care and Use of Laboratory Animals, U.S. Department of Health, Education and Welfare Publication No. (NIH) 73–23.