Should acyclovir prophylaxis be used in late pregnancy in women with recurrent genital herpes infection? How to use a clinical decision analysis

Contact stomatitis is rather uncommon because of the relative resistance of the oral mucosa to irritant agents and allergens. The clinical manifestations of contact stomatitis are extremely variable and include erythema, erosions, ulcerations, leukoplakia-like lesions, and lichenoid reactions. Clinical signs are frequently less pronounced than subjective symptoms, and patients commonly experience severe functional problems despite only mild mucosal alterations. Allergic stomatitis is rare and almost always attributable to metallic mercury and gold salts. A careful history and an accurate examination of the oral cavity, teeth, and dental restorations are essential for a correct diagnosis. Patch testing is indicated in all lesions that are not clearly related to trauma or physical injuries. Patch testing is not useful in the burning mouth syndrome. Evaluation of clinical relevance of patch test results is always very difficult and requires an interdisciplinary approach to the patient. Successful treatment requires the identification and elimination of the causative factor, when possible. It is important to bear in mind that replacement of dental restorations and prostheses may be very expensive and stressful for the patient and thus should not be recommended when their causative role is doubtful.     

Effect of crosslinking agent content, monomer functionality, and repeat unit chemistry on properties of unfilled resins

Seven mechanical/physical properties were used to evaluate 10 unfilled resins: eight aromatic dimethacrylates and two urethane dimethacrylates. Physical property tests included compressive strength, Young's modulus in compression, uniaxial tensile strength, intrinsic yield point, toothbrush abrasion, Knoop hardness, and water sorption. Controlled changes were made in the following four material parameters: amount of crosslinking diluent present in the uncured monomer, functionality of the monomer, repeat unit chemistry of the monomer (urethane vs. aromatic structure) and mode of activation (chemical vs. visible light). Polymers containing a high concentration of crosslinking agent (50 wt%) were found to be tougher and to possess lower hardness than materials containing lesser amounts of crosslinking agent. This was attributed to the flexible nature of the triethylene glycol dimethacrylate crosslinking molecule. Exposure to water plasticized the highly crosslinked materials to the degree that the yield point and elastic modulus were effectively lowered. Most of the tested properties were unaffected by differences in functionality except resistance to toothbrush abrasion, which was enhanced for polymers derived from high functionality monomers. The urethane-based polymers sorbed substantially more water than the aromatic-based materials, which presumably resulted in lower values for surface hardness. However, the urethane resins were very tough, and excellent resistance to toothbrush abrasion was observed. Property differences caused by differences in activation mode were small, although the visible light materials did sorb more water.     

The effect of particle distribution on damage formation in particulate reinforced metal matrix composites deformed in compression

Image analysis results are reported on the generation of damage in particulate reinforced metal matrix composites during compressive deformation. The technique allows the automated collection of data on the incidence of particle fracture and void formation in the matrix as a function of important microstructural parameters such as local particle volume fraction and particle size. There is a strong relationship between damage and the local volume fraction of the reinforcement proving that damage formation is accentuated in regions of particle clustering. With the SiC reinforced materials examined, there was observed to be a change in dominance of damage mechanism from particle fracture at low local volume fractions to void formation in the matrix within strongly clustered regions. The results are compared with finite element (FE) modelling of the compressive deformation of clustered particles using a simple cluster of equi-spaced particles. The FE results suggest that plastic flow is generally inhibited in clustered regions. In certain highly clustered configurations shielding is such that flow does not occur in the heart of the cluster even at high levels of average plastic strain. The modelling suggests that the change in dominance of damage mechanism is related to the dramatic increase in tensile hydrostatic stresses in the matrix with higher levels of particle clustering.     

Stochastic complexity measures for physiological signal analysis

Traditional feature extraction methods describe signals in terms of amplitude and frequency. This paper takes a paradigm shift and investigates four stochastic-complexity features. Their advantages are demonstrated on synthetic and physiological signals; the latter recorded during periods of Cheyne-Stokes respiration, anesthesia, sleep, and motor-cortex investigation     

Reaction time during cocaine versus alcohol withdrawal: longitudinal measures of visual and auditory suppression

Visual and auditory stimulus discrimination tasks, analogous to those used in the Reitan-Klove Sensory Perceptual Examination, were performed by 12 cocaine-dependent and 5 alcohol-dependent patients after 1 week, 3 weeks, and 3 months of verified abstinence. Sixteen control subjects, who were not substance-dependent, performed the same tasks after comparable intervals. During each task, either visual or auditory stimuli were presented in the left, in the right, or in both sensory fields. A simple key press was made to discriminate these conditions. Cocaine-dependent patients responded more slowly than control subjects during both tasks. The reaction-time slowing persisted across all three sessions, spanning a 3-month period of abstinence. There were no significant differences between the cocaine-dependent and control groups in response accuracy. In the context of other findings, these findings are interpreted as reflecting an enduring effect of prior cocaine dependence on motor as opposed to sensory functioning.     

Inhibition of G1 cyclin-dependent kinase activity during growth arrest of human breast carcinoma cells by prostaglandin A2

Prostaglandin A2 (PGA2) potently inhibits cell proliferation and suppresses tumor growth in vivo, but little is known regarding the molecular mechanisms mediating these effects. Here we demonstrate that treatment of breast carcinoma MCF-7 cells with PGA2 leads to G1 arrest associated with a dramatic decrease in the levels of cyclin D1 and cyclin-dependent kinase 4 (cdk4) and accompanied by an increase in the expression of p21. We further show that these effects occur independent of cellular p53 status. The decline in cyclin D and cdk4 protein levels is correlated with loss in cdk4 kinase activity, cdk2 activity is also significantly inhibited in PGA2-treated cells, an effect closely associated with the upregulation of p21. Immunoprecipitation experiments verified that p21 was indeed complexed with cdk2 in PGA2-treated cells. Additional experiments with synchronized MCF-7 cultures stimulated with serum revealed that treatment with PGA2 prevents the progression of cells from G1 to S. Accordingly, the kinase activity associated with cdk4, cyclin E, and cdk2 immunocomplexes, which normally increases following serum addition, was unchanged in PGA2-treated cells. Furthermore, the retinoblastoma protein (Rb), a substrate of cdk4 and cdk2 whose phosphorylation is necessary for cell cycle progression, remains underphosphorylated in PGA2-treated serum-stimulated cells. These findings indicate that PGA2 exerts its growth-inhibitory effects through modulation of the expression and/or activity of several key G1 regulatory proteins. Our results highlight the chemotherapeutic potential of PGA2, particularly for suppressing growth of tumors lacking p53 function.     

Common region of ALL-1 gene disrupted in epipodophyllotoxin-related secondary acute myeloid leukemia

Translocations at chromosomal band 11q23 characterize most de novo acute lymphoblastic leukemias (ALL) of infants, acute myeloid leukemias (AML) of infants and young children, and secondary AMLs following epipodophyllotoxin exposure. The chromosomal breakpoints at 11q23 have been cloned from isolated cases of de novo ALL and AML. Using an 859-base pair BamHI fragment of human ALL-1 complementary DNA that recognizes the genomic breakpoint region for de novo ALL and AML, we investigated two cases of secondary AML that followed etoposide-treated primary B-lineage ALL. In the first case, the translocation occurred between chromosomes 9 and 11 and the breakpoint at 11q23 localized to the same 9-kilobase region of the ALL-1 gene that is disrupted in most of the de novo leukemias. In the second case the translocation was between chromosomes 11 and 19. The breakpoint occurred outside of the ALL-1 breakpoint cluster region.     

Reproductive senescence predicts cognitive decline in aged female monkeys

The present investigation provide evidences from a non-human primate model that naturally occurring menopause predicts a prominent signature of age-related cognitive decline. Young and aged rhesus monkeys were tested on a delayed response (DR) task known to the sensitive to aging, and reproductive status was evaluated according to menstrual cyclicity and urinary hormone profiles. Peri-/postmenopausal monkeys exhibited significant DR impairments relative to either age-matched premenopausal females, or young control subjects. In addition, markers of endocrine decline in the aged animals were selectively correlated with behavioral performance measures that distinguished premenopausal and peri-/postmenopausal monkeys. These results document that menopause is coupled to cognitive decline in the monkey, and they establish a valuable primate model for defining the effects of endocrine aging on brain and behavioral function.