Morphologic diversity in malignant melanoma: the potential use of microdissection and the polymerase chain reaction for diagnosis

Malignant melanoma (MM) can mimic soft tissue (ST) and epithelial neoplasms. An immunoperoxidase (IP) panel and a morphologic comparison of the primary are used in diagnosis, which can be difficult when the morphologic and IP profiles of a metastatic lesion simulate those of an ST neoplasm. Through the comparison of known genetic abnormalities in primary and metastatic neoplasms, a definitive diagnosis can be suggested on the basis of the finding of identical allelic losses through the use of microdissection (MD) and the polymerase chain reaction (PCR). Genetic alterations involving the p16 gene on chromosome 9p21 have been observed in MM. We present the case of a 56-year-old man with known MM in whom multiple metastatic lesions to the skin and an adrenal gland developed during a 5-year period. A fine-needle aspiration (FNA) of a new ST buttock lesion was performed; the specimen had cytologic features different from those of the primary neoplasm and simulated a possible primary ST neoplasm. We attempted to make a definitive diagnosis of MM in the FNA of the ST buttock lesion through a genetic comparison with the primary neoplasm as well as with the other metastatic sites. Direct-visualization MD was performed on histologic glass slides of the primary and adjacent tissue (normal control), and the metastatic lesions, along with malignant cell clusters from the buttock lesion FNA. DNA was extracted and PCR amplified with primers D9S171 and IFNA for the p16 locus at the 9p21-22 region. Loss of heterozygosity for the D9S171 marker at the p16 gene locus was identified in all of the neoplastic tissue tested. Normal skin elements did not show deletion. The combination of MD and PCR are powerful tools that can be used for the comparison of genetic abnormalities in primary and metastatic neoplasms with unusual morphologic features to help support a diagnosis with a noncontributory IP.     

The catalytic properties of murine carbonic anhydrase VII

Carbonic anhydrase VII (CA VII) appears to be the most highly conserved of the active mammalian carbonic anhydrases. We have characterized the catalytic activity and inhibition properties of a recombinant murine CA VII. CA VII has steady-state constants similar to two of the most active isozymes of carbonic anhydrase, CA II and IV; also, it is very strongly inhibited by the sulfonamides ethoxzolamide and acetazolamide, yielding the lowest Ki values measured by the exchange of 18O between CO2 and water for any of the mammalian isozymes of carbonic anhydrase. The catalytic measurements of the hydration of CO2 and the dehydration of HCO3- were made by stopped-flow spectrophotometry and the exchange of 18O using mass spectrometry. Unlike the other isozymes of this class of CA, for which Kcat/K(m) is described by the single ionization of zinc-bound water, CA VII exhibits a pH profile for Kcat/K(m) for CO2 hydration described by two ionizations at pKa 6.2 and 7.5, with a maximum approaching 8 x 10(7) M-1 s-1. The pH dependence of kcat/K(m) for the hydrolysis of 4-nitrophenyl acetate could also be described by these two ionizations, yielding a maximum of 71 M-1 s-1 at pH > 9. Using a novel method that compares rates of 18O exchange and dehydration of HCO3-, we assigned values for the apparent pKa at 6.2 to the zinc-bound water and the pKa of 7.5 to His 64. The magnitude of Kcat, its pH profile, 18O-exchange data for both wild-type and a H64A mutant, and inhibition by CuSO4 and acrolein suggest that the histidine at position 64 is functioning as a proton-transfer group and is responsible for one of the observed ionizations. A truncation mutant of CA VII, in which 23 residues from the amino-terminal end were deleted, has its rate constant for intramolecular proton transfer decreased by an order of magnitude with no change in Kcat/K(m). This suggests a role for the amino-terminal end in enhancing proton transfer in catalysis by carbonic anhydrase.     

Effects of a long-term inhalation of fragrances on the stress-induced immunosuppression in mice

The aim of this study was to determine the effects of the long-term application of various fragrances on the suppression of immune response induced by high-pressure stress in mice. The immune response was analyzed based on plaque-forming cell (PFC) count, using mice sensitized with sheep red blood cells. The decreased PFC involving thymic involution induced by high-pressure stress in mice was restored by exposing the stressed mice to tuberose, lemon, oakmoss and labdanum for 24 h following exposure to stress. The decreased PFC and thymic involution from stress were restored by exposure to lemon and oakmoss, but not to tuberose and labdanum when the mice were exposed to those fragrances continuously for 3 weeks before the stress was given, followed by exposure to the same fragrances for 24 h after the stress. The decreased PFC and thymic involution from stress were restored by exposure to lemon and labdanum for 24 h after the stress, but not to tuberose over 3 weeks before the stress was given. These data suggest that the neuroimmunomodulatory effects of fragrances may be affected by tolerance depending on the kinds of fragrances in the case of a long-term application.     

The Prize of the President of the Republic of Tunisia for Inter-Maghreb Medical Societies

Results of a recent study of data from the National Health and Nutrition Examination Survey (NHANES I) on sodium intake and all-cause and cardiovascular mortality may call into question current recommendations to limit salt intake. Further research is needed to explore the relationship between sodium, cardiovascular disease, and mortality.