Design and performance of an ultraviolet resonance Raman spectrometer for proteins and nucleic acids.

We describe an ultraviolet resonance Raman (UVRR) spectrometer appropriate for structural studies of biological macromolecules and their assemblies. Instrument design includes the following features: a continuous wave, intracavity doubled, ultraviolet laser source for excitation of the Raman spectrum; a rotating cell (or jet source) for presentation of the sample to the laser beam; a Cassegrain optic with f/1.0 aperture for collection of the Raman scattering; a quartz prism dispersing element for rejection of stray light and Rayleigh scattering; a 0.75-m single grating monochromator for dispersion of the Raman scattering; and a liquid-nitrogen-cooled, charge-coupled device for detection of the Raman photons. The performance of this instrument, assessed on the basis of the observed signal-to-noise ratios, the apparent resolution of closely spaced spectral bands, and the wide spectrometer bandpass of 2200 cm-1, is believed superior to previously described UVRR spectrometers of similar design. Performance characteristics of the instrument are demonstrated in UVRR spectra obtained from standard solvents, p-ethylphenol, which serves as a model for the tyrosine side chain, the DNA nucleotide deoxyguanosine-5'-monophosphate, and the human tumor necrosis factor binding protein, which is considered representative of soluble globular proteins.

Prognostic significance of carcinoembryonic antigen in colorectal carcinoma. Serum levels before and after resection and before recurrence.

The use of carcinoembryonic antigen was evaluated in 425 patients with a mean follow-up of 48 months. The preoperative and postoperative carcinoembryonic antigen levels were predictive of recurrence and survival independent of the tumor stage. In a multivariate regression analysis of age, location, tumor stage, and preoperative and postoperative carcinoembryonic antigen levels, the latter three factors were significant prognostic variables with respect to the adjusted survival. Recurrent disease was found in 42% of patients, excluding patients with stage IV disease. The carcinoembryonic antigen level at recurrence was greater than 5 ng/mL in 79% of the patients and in 89% of the intra-abdominal recurrences. Carcinoembryonic antigen level at recurrence was not predictive of postrecurrence survival except in the subgroup of locoregional disease. The life span in patients with liver and lung metastases was not influenced by carcinoembryonic antigen level at recurrence. Preoperative and postoperative carcinoembryonic antigen levels can indicate a poorer prognostic group of patients with colorectal cancer who may benefit from adjuvant treatment. The carcinoembryonic antigen at recurrence can be used effectively to diagnose intra-abdominal recurrences and project survival after development of local/regional disease.

When is polypectomy sufficient treatment for colorectal cancer in a polyp?

Eighty-seven patients with a carcinoma in a polyp were reviewed over a 12-year period. Ten histologic criteria were analyzed for an association with the presence of residual carcinoma. Four factors were identified as having prognostic value: size greater than 1.5 cm, sessility, cancer of at least 50% of the adenoma volume, and invasive carcinoma. Polypectomy alone is adequate treatment unless the carcinoma invades deeper to the muscularis mucosa and is associated with one or more of these characteristics.