Treatment considerations for posterior laboratory-fabricated composite resin restorations

A variety of techniques are currently available to restore dentition in the posterior region, and the selection of the proper modality is dependent upon evaluation and satisfaction of numerous criteria. Direct materials provide limited strength in the posterior segment, and full-coverage indirect techniques (e.g., crown restorations) often require the destruction of sound tooth structure. When proper case selection, preparation design, and clinical protocols are utilized, a laboratory-processed composite resin (belleGlass, Kerr/Sybron, Orange, CA) can provide an optimal means by which to successfully restore posterior dentition without compromising the existing tooth structure.     

Updating protections for human subjects involved in research. Project on Informed Consent, Human Research Ethics Group

For decades, all federally funded research involving human subjects has been subject to regulations that require the informed consent of the subject and oversight by the local institution. These regulations last underwent major revision in 1981 and have remained unchanged despite significant changes in the nature of clinical science, the financial sources of research support, and the institutional environment in which clinical research is conducted. In the intervening years, doubt has evolved as to whether the regulations currently in place adequately protect the welfare and rights of research subjects in today's clinical research environment and whether the costs, in terms of time, bureaucracy, and delay, are justified by the level of protection afforded. The Human Research Ethics Group, administered by the Center for Bioethics at the University of Pennsylvania Health System, extensively reviewed the status of existing human subjects protections with the aim of making recommendations to improve and reform the regulations. Here, we present recommendations constituting a consensus of the group members for reform in 3 key areas: protecting subject populations with special needs and vulnerabilities, oversight by institutional review boards, and regulatory policy.     

Renal clearance, tissue distribution, and CA-125 responses in a phase I trial of suramin

Exposure of human spermatozoa to nicotinamide adenine dinucleotide phosphate (NADPH) resulted in the dose dependent generation of reactive oxygen species (ROS) which, at a critical level of intensity, induced lipid peroxidation, DNA damage and a dramatic decline of sperm motility. This system was then used as a model for screening the ability of different antioxidants to combat oxidative stress created through the excessive intracellular generation of toxic oxygen products of metabolism. A variety of antioxidants that has previously been shown to be protective against extracellularly derived oxidants (e.g. superoxide dismutase, catalase, vitamin E, hypotaurine) were ineffective in this system. Albumin, however, could provide complete protection against NADPH induced oxidative stress via mechanisms that did not involve the suppression of the lipid peroxidation cascade but rather the inactivation of lipid peroxides generated during this process. Albumin did not protect against DNA damage induced by NADPH but was extremely effective at preventing DNA fragmentation arising from the suppression of glutathione peroxidase activity with mercaptosuccinate. These studies emphasize that the design of clinically effective antioxidant treatments will depend, critically, upon the source of the oxidative stress. For cases involving excessive intracellular ROS generation, albumin appears to be an important means of neutralizing lipid peroxide-mediated damage to the sperm plasma membrane and DNA.     

Protein kinase B kinases that mediate phosphatidylinositol 3,4,5-trisphosphate-dependent activation of protein kinase B

Protein kinase B (PKB) is activated in response to phosphoinositide 3-kinases and their lipid products phosphatidylinositol 3,4, 5-trisphosphate [PtdIns(3,4,5)P3] and PtdIns(3,4)P2 in the signaling pathways used by a wide variety of growth factors, antigens, and inflammatory stimuli. PKB is a direct target of these lipids, but this regulation is complex. The lipids can bind to the pleckstrin homologous domain of PKB, causing its translocation to the membrane, and also enable upstream, Thr308-directed kinases to phosphorylate and activate PKB. Four isoforms of these PKB kinases were purified from sheep brain. They bound PtdIns(3,4,5)P3 and associated with lipid vesicles containing it. These kinases contain an NH2-terminal catalytic domain and a COOH-terminal pleckstrin homologous domain, and their heterologous expression augments receptor activation of PKB, which suggests they are the primary signal transducers that enable PtdIns(3,4,5)P3 or PtdIns- (3,4)P2 to activate PKB and hence to control signaling pathways regulating cell survival, glucose uptake, and glycogen metabolism.     

Clinical factors contributing to the differential diagnosis of primary insomnia and insomnia related to mental disorders

OBJECTIVE: Primary insomnia and insomnia related to mental disorders are the two most common DSM-IV insomnia diagnoses, but distinguishing between them is difficult in clinical practice. This analysis was performed to identify clinical factors used by sleep specialists to distinguish primary insomnia from insomnia related to mental disorders. METHOD: Clinicians evaluated 216 patients referred for insomnia at five clinical sites, rated a list of clinical factors judged to contribute to each patient's presentation, and assigned diagnoses. Analysis of variance was performed, with contributing factors as the dependent variable and diagnostic group and clinic location as independent variables. RESULTS: Sleep specialists rated a psychiatric disorder as a stronger factor for insomnia related to mental disorders and rated negative conditioning and sleep hygiene as stronger factors for primary insomnia. However, a psychiatric disorder was rated as a contributing factor for 77% of patients who received a first diagnosis of primary insomnia. CONCLUSIONS: While neither sleep hygiene nor negative conditioning is a diagnostic criterion in DSM-IV, these results support the face validity of these clinical factors distinguishing between primary insomnia and insomnia related to mental disorders. The use of a psychiatric disorder as an inclusion criterion for insomnia related to mental disorders and an exclusion criterion for primary insomnia reinforces a categorical distinction between the two diagnoses, but the contribution of psychiatric symptoms in primary insomnia appears to be a clinically relevant one. These findings suggest the need for studies on the validity of negative conditioning and sleep hygiene in the etiology of primary insomnia, as well as on the significance of psychiatric disorders, especially depression, in primary insomnia.     

Regulation of stress-induced cytokine production by pyridinylimidazoles; inhibition of CSBP kinase

Members of three classes of pyridinylimidazoles bind with varying affinities to CSBP (p38) kinase which is a member of a stress-induced signal transduction pathway. Based upon SAR and protein homology modeling, the pharmacophore and three potential modes of binding to the enzyme are presented. For a subset of pyridinylimidazoles, binding is shown to correlate with inhibition of CSBP kinase activity, whereas no significant inhibition of PKA, PKC alpha and ERK kinase activity is observed.     

Fas ligand-induced apoptosis of infected human macrophages reduces the viability of intracellular Mycobacterium tuberculosis

Mycobacterium tuberculosis-specific cytolytic activity is mediated mostly by CD4+CTL in humans. CD4+CTL kill infected target cells by inducing Fas (APO-1/CD95)-mediated apoptosis. We have examined the effect of Fas ligand (FasL)-induced apoptosis of human macrophages infected in vitro with M. tuberculosis on the viability of the intracellular bacilli. Human macrophages expressed Fas and underwent apoptosis after incubation with soluble recombinant FasL. In macrophages infected either with an attenuated (H37Ra) or with a virulent (H37Rv) strain of M. tuberculosis, the apoptotic death of macrophages was associated with a substantial reduction in bacillary viability. TNF-induced apoptosis of infected macrophages was coupled with a similar reduction in mycobacterial viability, while the induction of nonapoptotic complement-induced cell death had no effect on bacterial viable counts. Infected macrophages also showed a reduced susceptibility to FasL-induced apoptosis correlating with a reduced level of Fas expression. These data suggest that apoptosis of infected macrophages induced through receptors of the TNF family could be an immune effector mechanism not only depriving mycobacteria from their growth environment but also reducing viable bacterial counts by an unknown mechanism. On the other hand, interference by M. tuberculosis with the FasL system might represent an escape mechanism of the bacteria attempting to evade the effect of apoptosis.     

Abnormalities of epithelial apoptosis in multistep colorectal neoplasia demonstrated by terminal deoxyuridine nick end labeling

Colonic carcinogenesis is accompanied by progressive genetic changes and alterations in growth control. To examine whether abnormalities of apoptosis are involved in carcinogenesis, we examined epithelial apoptosis in formalin-fixed normal and neoplastic colon by terminal uridine deoxynucleotide nick end-labeling (TUNEL) histochemistry. In normal colon, resection margins, and hyperplastic polyps, TUNEL-positive cells comprised around 3% of total colonocytes, with over 85% of these cells located in surface epithelium between crypts. In adenomas, there were significantly fewer TUNEL-positive cells at the luminal surface than normal (1.82 +/- 0.51% of epithelial cells, compared with 12.1 +/- 2.3%, P < 0.05) and a trend to increased numbers at the crypt base (2.70 +/- 0.98% compared with 0.65 +/- 0.15%). Carcinomas contained fewer TUNEL-positive cells than normal (1.7 +/- 0.27%), and they are randomly distributed. Transitional mucosa had significantly more TUNEL-positive colonocytes than normal (11.0 +/- 3.0%, P < 0.005), both at the surface and crypt base. These results show that colonocyte apoptosis normally occurs mainly in luminal cells but that early during carcinogenesis the distribution and quantity of apoptotic cells changes.     

14-3-3 proteins are required for maintenance of Raf-1 phosphorylation and kinase activity

By binding to serine-phosphorylated proteins, 14-3-3 proteins function as effectors of serine phosphorylation. The exact mechanism of their action is, however, still largely unknown. Here we demonstrate a requirement for 14-3-3 for Raf-1 kinase activity and phosphorylation. Expression of dominant negative forms of 14-3-3 resulted in the loss of a critical Raf-1 phosphorylation, while overexpression of 14-3-3 resulted in enhanced phosphorylation of this site. 14-3-3 levels, therefore, regulate the stoichiometry of Raf-1 phosphorylation and its potential activity in the cell. Phosphorylation of Raf-1, however, was insufficient by itself for kinase activity. Removal of 14-3-3 from phosphorylated Raf abrogated kinase activity, whereas addition of 14-3-3 restored it. This supports a paradigm in which the effects of phosphorylation on serine as well as tyrosine residues are mediated by inducible protein-protein interactions.