Antibiotic-associated hemorrhagic colitis.

Antibiotic-associated hemorrhagic colitis is an infrequently recognized, self-limited process that may be experienced by patients receiving oral penicillin derivatives, primarily for upper respiratory infections. Symptoms of diarrhea, abdominal tenderness, and ultimately bloody diarrhea occur within one week of antibiotic use. Resolution of symptoms typically occurs within three days of discontinuing the offending antibiotic. Previous reports have suggested a non-inflammatory process involving the right colon. We present four cases and review the literature with respect to presentation, diagnosis, course, and postulated pathophysiologic mechanisms. Our patients demonstrate a more heterogeneous population than previously noted. This disease can affect young and old, male and female, and can involve the entire colon. Active inflammation demonstrated by fecal leukocytes, peripheral leukocytosis, and an active inflammatory infiltrate on biopsy are reported.

Tuberous sclerosis complex: review of the gastrointestinal manifestations and report of an unusual case.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder that can affect any organ of the body. We report the first case of advanced colonic adenocarcinoma in a patient with well-documented TSC, offer rationales for the association of this lesion with TSC, and review the literature pertaining to gastrointestinal involvement of this complex.

Cell kinetic effects of incorporated 3H-thymidine on proliferating human lymphocytes: flow cytometric analysis using the DNA/nuclear protein method.

Phytohemagglutinin-stimulated human peripheral blood lymphocytes incorporating high concentrations of 3H-thymidine accumulate in G2 and show a consequent reduction in the number of cells entering M (division delay). The simultaneous flow cytometric analysis of DNA content (propidium iodide fluorescence) and nuclear protein content (fluorescein isothiocyanate fluorescence) allows for the accurate quantitation of these events; G2 and M are separated in the bivariate distributions. A good correlation was observed between mitotic indices, quantitated by manually counting mitotic cells, and integration of the M area in DNA/nuclear protein histograms. Moreover, significant differences in G2 nuclear protein levels were found between untreated and 3H-thymidine-treated lymphocytes. In order to characterize this effect, G2 was empirically divided into low nuclear protein (G2A) and high nuclear protein (G2B) compartments. 3H-thymidine caused an initial accumulation of lymphocytes in G2A, followed within 3-6 h by a gradual movement of some cells into G2B, with a subsequent accumulation of cells in G2B. The results suggest that the distribution of cells in G2 (G2A and G2B), the average nuclear protein content of G2B cells, and the proportion of cells in M are parameters that when used in combination provide a unique description of radiobiological effects.

Quantitation of cell kinetic responses using simultaneous flow cytometric measurements of DNA and nuclear protein.

A rapid procedure was developed for the simultaneous flow cytometric analysis of nuclear protein using fluorescein isothiocyanate, and DNA using propidium iodide in isolated nuclei. The staining procedure did not involve centrifugation and was easily adapted to the staining of human peripheral blood lymphocytes stimulated with phytohemagglutinin, EL4 murine lymphoid tumor cells in suspension culture, and R3327-G rat prostatic adenocarcinoma solid tumor specimens. Histograms of unstimulated and PHA-stimulated HPBL perturbed by actinomycin D, hydroxyurea, 3H-TdR, colcemid, or hydroxyurea + colcemid showed that 1) resting, noncycling G1 (G1Q) cells are distinguished from late G1 (G1AB) cells, 2) early G2 (G2A) cells are distinguished from late G2 (G2B) cells, and 3) mitotic cells are distinguished from G2 cells. Treatment with hydroxyurea resulted in a build-up of cells having high nuclear protein content and 2C DNA content (G1AB), while incubation with 3H-TdR caused an increase in the number of cells with high nuclear protein content and 4C DNA content (G2B). Colcemid-blocked mitotic cells were identified as having low nuclear protein content (lower than G2A nuclei) and 4C DNA content. The nuclear DNA/protein histograms of untreated and colcemid-treated log-phase EL4 cells provided information concerning G1A, G1B, S, G2A, G2B, and M. The method was also used to quantitate the response of androgen-sensitive rat prostatic R3327-G tumors to androgen deprivation following castration. Sample preparation and staining for correlated nuclear DNA/protein measurements takes approximately the same amount of time as for single parameter nuclear DNA measurements.