Immunohistochemical performance of antibodies on previously frozen tissue.

Immunohistochemical stains are occasionally performed on paraffin-embedded, fixed material that was previously frozen, most frequently for an intraoperative frozen section diagnosis. A retrospective study comparing immunohistochemistry on previously frozen then fixed tissue with freshly fixed tissue was designed. Of 43 cases identified during the period 1994-1996 in which immunohistochemistry was performed on frozen section blocks, 19 met criteria for inclusion. Immunohistochemistry using antibodies to S-100, HMB-45, synaptophysin, chromogranin, neuron-specific enolase (NSE), neurofilament, glial fibrillary acidic protein, vimentin, and carcinoembryonic antigen (CEA) was compared. Staining for cytokeratins was unchanged. Staining for S-100, HMB-45, synaptophysin, and NSE were negative in frozen/fixed tissue and positive in comparable fresh/fixed tissue in at least one case each. Chromogranin and CEA exhibited a significant decrease in the frozen/ fixed tissue. We conclude that caution must be exercised in interpreting immunohistochemical results using tissue that was frozen for intraoperative consultation before formalin fixation and paraffin embedding.

Cytologic diagnosis of metastatic ovarian adenocarcinoma in the urinary bladder: a case report and review of the literature.

A 53-yr-old woman with a 13-mo history of recurrent ovarian papillary serous adenocarcinoma presented with persistent microscopic hematuria. The patient was undergoing chemotherapy for her recurrent ovarian tumor when she was referred to the urology service for microscopic hematuria. An intravenous pyelogram was normal. Cystoscopy was performed, as well as a urinary bladder washing and mucosal biopsies for examination. Adenocarcinoma similar to the patient's primary ovarian tumor was detected in both cytology and histopathology specimens. Ovarian carcinoma comprises 1.3-4.0% of all metastatic neoplasms to the urinary bladder and is an important consideration in the differential diagnosis of a cytologic finding of adenocarcinoma in urine specimens of female patients, where it accounts for an even higher percentage of cases (1 of 3 adenocarcinoma diagnoses in a series of 4,677 urine specimens from female patients).

Comparison of the intracellular metabolism and trafficking of 25-hydroxycholesterol and cholesterol in macrophages.

Oxysterols arising from the diet or through lipid peroxidation may be important in the modulation of cellular cholesterol metabolism. In this study, the metabolism of one of the oxysterols, 25-hydroxycholesterol (25OHC), was examined in J774 and mouse peritoneal macrophages. Uptake of 25OHC from serum was rapid and substantial. Esterification of the cellular 25OHC was also rapid as was hydrolysis of pre-formed esters. Like cholesterol, 25OHC was removed from cells by an extracellular acceptor such as high density lipoprotein. Unlike cholesterol, 25OHC was also rapidly and extensively removed from cells by serum albumin, but not by ovalbumin. The differential removal of oxysterols and cholesterol from cells by albumin allows separation of cellular effects due to oxysterols and cholesterol. In order to understand more about this differential efflux of sterols, a computer model for sterol mass transport in cells was used to compare intracellular trafficking of cholesterol and 25OHC. The rate constants determined by this model for movement of sterols between cytoplasm and plasma membrane were similar for both cholesterol and 25OHC, whereas those for esterification and ester hydrolysis as well as those for bidirectional movement between plasma membrane and extracellular medium were greater for 25OHC than for cholesterol. For both sterols, the rate-limiting step for removal of cellular esters appeared to be the rate of cytoplasmic ester hydrolysis. As 25OHC and cholesterol differ significantly in aqueous solubility, the similarity in their rate constants for movement between cytoplasm and plasma membrane is consistent with facilitation of transport between these two loci.

Thermodynamics of halobacterial environments.

The ranges of the major ion composition of near neutral hypersaline lakes have been described in terms of the charge concentration and the mole fraction of monovalent cations. An ion interactive method was used to establish the thermodynamic activity of the chemical species in these model brines, which were then used in culture media for Halobacterium halobium, H. salinarium, and H. volcanii. The bacteria grew rapidly at water activities of 0.78, 0.79, and 0.925, respectively. The growth areas for these organisms were not easily defined in terms of the Na+ or Cl- activity. The morphology of H. halobium and H. salinarium changes from rod shaped to spherical when the Mg2+ activity drops below 0.15 mol . kg-1. Niches described by the chemical parameters reflect the marine origin of the environments of H. halobium and H. salinarium, and the more heterogeneous environments of H. volcanii.

Investigations into the effect of acid on the spectral and kinetic properties of purple membrane from Halobacterium halobium.

The formation and reversal of the acid species of purple membrane generated below pH 4.00 (22 degrees C) is studied together with the photochemical cycle over the pH range 6.40--3.20. The buffering capacity of the membrane reaches a peak at pH 4.30, indicating the possibility of a conformational change taking place. The generation of the new spectral species can take place in the dark and is unaffected by the addition of reducing agents. Kinetic parameters measured indicate that the group being titrated below pH 4.00 could be the same as that protonated in the formation of intermediate O. The temporal placement of intermediate O after M in the photochemical cycle is shown to be incompatible with the data presented here. Reneutralization of acidified purple membrane shows that the spectral changes in acid are reversible but the phototransient properties are altered.

Studies of an acid-induced species of purple membrane from Halobacterium halobium.

A new spectral species of the purple membrane of Halobacterium halobium has been observed below pH 3.2. The formation of this new species is temperature-dependent and is favoured by increasing temperature up to the physiological range of the organism. The rate of formation at pH 3.0 and 22 degrees C is 7.9 x 10-3s-1. The spectral distribution and temperature-dependence of the new species suggest that it may be phototransiet O, stabilized by low pH. Flash-photolytic experiments in the pH range 7.2-2.7 show a pH-dependence corresponding to the static events and are consistent with a single protonation of bacteriorhodopsin below pH 3.22. These results can also be interpreted in terms of the stabilization of phototransient O at low pH. The temperature-dependence of the formation of the acid-induced species may reflect a relationship with the phase transition of the membrane.