Rim mandibulectomy for cancer of the oral cavity

Improvements in our understanding of the methods of mandibular invasion by malignancies and refinements in the biomechanical analysis of mandibular osteotomies led us to modify our standard operative procedure for this disease process. Over a 10 year period, we performed rim mandibulectomy to treat oral cavity malignancies with mandibular involvement. This retrospective analysis of 38 patients comparing rim mandibulectomy with the traditional segmental mandibulectomy has demonstrated equivalent local control rates between rim mandibulectomy and segmental resection (75 and 64 percent, respectively). Patients with rim mandibulectomies were more satisfied with their postoperative appearance, and some were able to wear lower dentures if well motivated. In performing the rim mandibulectomy, we found that smooth, curved osteotomies without step-offs resulted in a technically simple operation that was biomechanically sound and had a low complication rate. Rim mandibulectomy, because it is based on sound pathologic principles and does not disrupt the mandibular arch, is an operation that adequately resects the tumor without compromising the cancer operation or the patient.     

Chronological changes in pyridoxine-5'-phosphate oxidase immunoreactivity in the seizure-sensitive gerbil hippocampus

To identify the roles of pyridoxine-5'-phosphate (PNP) oxidase in epileptogenesis and the recovery mechanisms in spontaneous seizure, a chronological and comparative analysis of PNP oxidase expression was conducted. PNP oxidase immunoreactivity in a preseizure group of seizure-sensitive (SS) gerbils was detected more strongly than that in a seizure-resistant (SR) group. The density of PNP oxidase immunoreactivity in a 30 min postictal group was significantly lower than that in a preseizure group. In a 12 hr postictal group, PNP oxidase immunodensity had recovered to a preseizure level. The overexpression of PNP oxidase in the hippocampus of preseizure SS gerbils suggests that PNP or pyridoxal 5'-phosphate plays an important role in the modulation of glutamic acid decarboxylase activity and gamma-aminobutyric acid reuptake as mediated by membrane transporter via neurons. In addition, this change in the PNP oxidase immunoreactivity following seizure may be a compensatory response designed to reduce epileptic activity in this animal.     

Alcohol and nicotine reduce cell proliferation and enhance apoptosis in dentate gyrus

It is generally accepted that alcohol and nicotine affect learning ability and memory functions, especially in adolescents. In the present study, the effects of alcohol and nicotine on cell proliferation and apoptosis in the dentate gyrus of young rats were investigated. The results show that cell proliferation is suppressed by alcohol and nicotine. Furthermore, alcohol and nicotine increase the number of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive cells. Based on the results presented in this study, it can be suggested that alcohol- and nicotine-related impairment in learning and memory functions may be due to alcohol- and nicotine-induced suppression of new cell formation and acceleration of apoptosis, especially during adolescence.     

Changes in pyridoxal kinase immunoreactivity in the gerbil hippocampus following spontaneous seizure

To identify the roles of pyridoxal kinase (PLK) in epileptogenesis and the recovery mechanisms in spontaneous seizure, a chronological and comparative analysis of PLK expression in the gerbil hippocampus was conducted. PLK immunoreactivity in a pre-seizure group of seizure sensitive (SS) gerbils was more strongly detected than that in a seizure resistant (SR) group. The density of PLK immunoreactivity in a 30-min postictal group was significantly lower than that of a pre-seizure group. In a 12 h postictal group, PLK immunodensity recovered to pre-seizure level. The over-expression of PLK in the hippocampus of pre-seizure SS gerbils suggests that PLP play an important role in the modulation of GAD activity and GABA reuptake as mediated by membrane transporter via neurons.     

Effect of tumor necrosis factor-alpha, interferon-gamma, and transforming growth factor-beta on adipogenesis and expression of thyrotropin receptor in human orbital preadipocyte fibroblasts

Graves' ophthalmopathy (GO) is an orbital autoimmune disease that is closely associated with Graves' hyperthyroidism. Examination of retroorbital tissues in GO reveals an accumulation of glycosaminoglycans, increased fat volume, lymphocytic infiltration, and the presence of several inflammatory cytokines. A subpopulation of human orbital fibroblasts can be differentiated in vitro into cells with the morphologic features of adipocytes. We demonstrated recently that these differentiated cultures show increased expression of functional TSH receptor (TSHr). To determine whether the presence of inflammatory cytokines might impact adipogenesis or TSHr expression in these cultures, we treated orbital fibroblasts from normal individuals or GO patients with tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), or transforming growth factor-beta. We found that each of these cytokines inhibits TSH-dependent cAMP production and TSHr gene expression, and that TNF-alpha and IFN-gamma also inhibit morphological adipocyte differentiation. When cytokines were added after differentiation, the inhibition was less pronounced. Our results suggest that TNF-alpha, IFN-gamma, and transforming growth factor-beta may act within the orbit in GO to modulate expression of the putative orbital autoantigen, TSHr. In addition, the former two cytokines may play a role in determining the extent to which the volume of the orbital adipose tissue increases in this condition.     

Ethical issues in investigation of screening strategies

Screening programs can be designed to be useful for data collection to study effectiveness of screening. High-risk populations may be identified, and screening techniques applied to a randomly selected subgroup with another subgroup serving as controls. This raises the ethical question of not applying helpful surveillance to individuals known to be at high-risk. Attention should be paid to management of controls, for example, to screen them less frequently, or at least to inform them of their increased risk and advise periodic exams. Against such recommendations is that differences between test and control groups would be minimized and the study less conclusive. Another approach is to use adaptive design, selecting the study group from a large population which is being subject to medical surveillance for some other reason. As in other clinical trails, studies of screening programs must include appropriate surveillance for controls to properly safeguard their rights and medical needs.     

Experimental endocarditis induced by dental manipulation and oral streptococci.

Circumstantial evidence has strongly implicated dental manipulation as an etiologic factor in the development of infective endocarditis. The introduction of human oral streptococci via the oral cavity in rabbits with vegetative cardiac lesions yields a 94 per cent incidence of infective endocarditis, if the number of inoculated organisms is above a threshold level of 10(7).