Study of normal colorectal tissue by FT-Raman spectroscopy.

FT-Raman spectroscopy was employed to study normal human colorectal tissues in vitro with the aim of evaluating the spectral differences of the complex colon mucous in order to establish a characteristic Raman spectrum. The samples were collected from 39 patients, providing 144 spectra for the statistical analysis. The results enable one to establish three well-defined spectroscopic groups of non-altered colorectal tissues that were consistently checked by statistical (clustering) and biological (histopathology) analyses: group 1 is represented by samples with the presence of epithelial layer, connective tissue papillae, and smooth muscle tissue; group 2 comprises tissues with epithelial layer and connective tissue papillae; group 3 presented mostly fatty and slack conjunctive tissue. The study reveals the existence of an intrinsic spectral variability for each patient that must be considered when sampling tissues fragments to build a spectral database. This is the first step for future studies and applications of Raman spectroscopy to optical biopsy and diagnosis of colorectal cancer.

Comparative efficacy of ceftriaxone in experimental infections involving Bacteroides fragilis and Escherichia coli.

The in vivo activity of ceftriaxone was examined in an experimentally induced subcutaneous infection involving Bacteroides fragilis and Escherichia coli. Mice were challenged with 1 of 10 strains of B. fragilis or E. coli, or a dual combination of the two species. The efficacy was measured by a reduction in the count of viable organisms when antimicrobial treatment was initiated 1 h after challenge and continued for 5 days. Ceftriaxone exhibited impressive activity against E. coli but showed poor in vivo activity versus B. fragilis. The antimicrobial activity of ceftriaxone was influenced by the microbial interaction in our dual-isolate model. Pharmacokinetic studies showed that ceftriaxone penetrated into abscesses and achieved peak levels of about 40% of the peak serum levels. However, in abscesses infected with B. fragilis nearly all biological activity of ceftriaxone was lost.

Kinetics study of immunological response to Clostridium botulinum toxin.

A double-antibody enzyme-linked immunosorbent assay (ELISA) for detection of humoral antibody to type A botulinal toxin was developed. This assay was used to study the kinetics of antibody response of a volunteer to botulinal toxoid. The circulating type A antitoxin was first detected by the ELISA 2 weeks after the first booster injection of the toxoid. The antibody titer stayed level until the second booster at 12 weeks. The titer then continued to rise throughout the remaining study period. The neutralizing antibody to type A toxin was detected by mouse assay 15 weeks after detection of antitoxin by the ELISA.

Accumulation of indium-111-labeled neutrophils and gallium-67 citrate in rabbit abscesses.

A rabbit abscess model was developed to study the effect of abscess age on the accumulation of indium-111-labeled neutrophils ([111In]N) versus gallium-67 citrate (67Ga). Abscesses 1-2 hr, 6-8 hr, 24 hr, and 7 days old were induced by subcutaneous injection of autoclaved colon contents prior to i.v. administration of either [111In]N or 67Ga. Radioactivity in the abscesses was determined 48 hr postinjection. Accumulation of [111In]N was inversely proportional to abscess age. Seven-day-old abscesses were inconsistently seen on [111In]N scans. In contrast, 67Ga accumulation was not affected by abscess age and all abscesses could be identified on a scan 48 hr postinjection. Scans with [111In]N were clearly superior to 67Ga scans for demonstrating early abscesses. Since 67Ga accumulated to a greater extent than [111In]N in abscesses 7 days old, it may be a superior imaging agent for older abscesses.