Use of a somatostatin analogue, octreotide acetate, in the management of acute gastrointestinal graft-versus-host disease

PURPOSE: Because the secretory diarrhea of acute graft-versus-host disease (GvHD) of the gut induces serious metabolic and nutritional disturbances, this study was initiated to assess the use of a somatostatin analogue, octreotide acetate, as adjunctive therapy for severe GvHD of the gut with massive diarrhea. PATIENTS AND METHODS: In a pilot study, six patients with biopsy-confirmed acute gut GvHD after allogeneic bone marrow transplantation received octreotide 50 to 250 micrograms three times a day subcutaneously. RESULTS: Three of the six treated patients had a prompt and dramatic reduction in stool volume within 1 to 3 days of initiation of octreotide therapy. CONCLUSIONS: Somatostatin and its analogues have been used successfully in diarrheal states by antagonism of neuropeptide overproduction, although other potential therapeutic mechanisms include inhibition of fluid secretion, enhanced salt absorption, and inhibition of gut motility. Somatostatin and its analogues may be promising adjunctive agents in the treatment of gastrointestinal GvHD, although assessment in a controlled trial will be required to confirm their therapeutic efficacy.     

Cocrystallization of an immunoglobulin light chain dimer with bis(dinitrophenyl) lysine: tandem binding of two ligands, one with and one without accompanying conformational changes in the protein

Previous studies showed that the Mcg dimer of immunoglobulin light chains bound bis(dinitrophenyl)lysine both in trigonal crystals and in solution. On prolonged storage in ammonium sulfate, mixtures of ligand and protein produced small trigonal cocrystals in low frequency. These crystals were nearly isomorphous with those of the unliganded dimer in which the subunits were covalently linked by an interchain disulfide bond. By difference Fourier analyses at 3.5 A resolution and subsequent crystallographic refinement, the cocrystals were found to contain molecules with two ligands aligned in tandem along the interface of the variable (V) domains of the protein. One ligand molecule adopted an almost fully extended conformation, with the epsilon-DNP ring situated near the floor, the alpha-carboxyl group directed toward the solvent at the entry, and the alpha-DNP ring outside the rim of the main cavity. As if architecturally designed, the ligand was located symmetrically between the two domains in an orientation that was compatible with both the unaltered structure of the cavity lining and with the known crystal packing interactions of neighboring protein molecules. The second ligand molecule in the cocrystal lodged in the deep pocket immediately under the floor of the main cavity. The ligand adopted a very compact conformation with the two DNP rings roughly antiparallel to each other. This molecule appeared to be semi-permanently sequestered in the pocket since it could not be dislodged by exhaustive perfusion with ammonium sulfate crystallizing media. Relative to its volume in the native dimer, the pocket was expanded to accommodate the oversized ligand. Within a single protein molecule, therefore, two types of binding of a flexible ligand were observed, one with and one without accompanying conformational changes in the protein. The number of cocrystals which could be produced was markedly increased if the interchain disulfide bond between the Mcg monomers was first reduced and alkylated.     

DNA polymerase mu gene expression in B-cell non-Hodgkin's lymphomas: an analysis utilizing in situ hybridization

DNA polymerase mu (pol mu) is a novel error-prone DNA repair enzyme bearing significant structural homology with terminal deoxynucleotidyltransferase. Whereas other human error-prone DNA polymerases identified thus far show no preferential lymphoid tissue distribution, the highest levels of pol mu mRNA have been detected in peripheral lymphoid tissues, particularly germinal center B cells. Conceivably, up-regulation of the pol mu gene may be biologically significant in lymphomagenesis, especially in the development of B-cell non-Hodgkin's lymphomas (B-NHLs), because of enhanced error-prone DNA repair activities. To explore this possibility, we generated a digoxigenin-labeled riboprobe to pol mu mRNA and used the probe and in situ hybridization to examine the expression pattern of the pol mu gene in formalin-fixed, paraffin-embedded tissue sections of 37 B-NHLs. This included eight chronic lymphocytic leukemia/small lymphocytic lymphomas, six mantle cell lymphomas, seven follicular lymphomas, nine diffuse large B-cell lymphomas, three splenic marginal zone lymphomas, two Burkitt's lymphomas, and two precursor B-lymphoblastic lymphomas. We also correlated the pol mu mRNA expression levels with the tumor proliferation index, which was assessed in each case by image analysis of Ki-67 immunostained slides. Nineteen of 21 (90%) B-NHLs arising from postgerminal center B cells (follicular lymphomas, diffuse large B-cell lymphomas, splenic marginal zone lymphomas, and Burkitt's lymphomas) exhibited high expression of pol mu mRNA. In contrast, only 2 of 16 (13%) B-NHLs arising from pregerminal center B cells (chronic lymphocytic leukemia/small lymphocytic lymphomas, mantle cell lymphomas, and precursor B-lymphoblastic lymphomas) expressed significant levels of pol mu mRNA. Pol mu gene expression did not seem to correlate with the proliferation index, especially because a significant level of pol mu mRNA was not detected in either case of precursor B-lymphoblastic lymphomas. In conclusion, pol mu gene expression is highly associated with B-NHLs of postgerminal center B-cell derivation. Furthermore, the expression level is independent of the proliferation rate and thus is unrelated to the biological aggressiveness of the tumors. These findings, along with the error-prone nature of the enzyme, suggest that up-regulation of pol mu gene expression may be a contributing factor to the pathogenesis of a subset of B-NHLs through DNA repair-associated genomic instability.     

Computerized cognitive testing in patients with type I Gaucher disease: effects of enzyme replacement and substrate reduction.

PURPOSE: Because of concern for drug-induced cognitive dysfunction during clinical trials using substrate reduction therapy (miglustat) in type 1 Gaucher disease and because it has been suggested that some patients with type 1 Gaucher disease may develop neurocognitive impairment as part of the natural history, two different batteries of neuropsychological tests were devised to examine these issues. Using these tests, cognitive function was assessed in patients treated with miglustat, in patients receiving enzyme replacement (standard care for symptomatic patients), and in untreated (milder) patients. METHODS: For this study, 55/60 patients exposed to miglustat in Israel participated in psychologist-administered testing; 36/55 participated in computerized testing. Of these, 31 enzyme-treated patients and 22 untreated patients participated in the psychologist-administered testing, and 15 enzyme-treated patients and 18 untreated patients participated in computerized testing. The psychologist-administered battery consisted of 18 standard neuropsychological subtests specific to executive and visuospatial functioning. The computerized battery (Mindstreams, NeuroTrax Corp., New York, NY) consisted of 10 subtests tapping multiple cognitive domains. Between-group analyses for each modality compared cognitive performance. RESULTS: In the psychologist-administered testing, patients exposed to miglustat performed significantly less well than the other groups in 5/18 subtests. On the computerized tests, all patients performed comparably to normal controls. Scores in patients exposed to miglustat were higher than in untreated patients, particularly in visuospatial function, whereas enzyme-treated patients performed less well. However, with the exception of visuospatial function, these results were not statistically significant. CONCLUSIONS: It is unclear why different testing methods yielded discordant results. Any dysfunction suggested by the current study is apparently subtle and of doubtful clinical relevance given that cognitive status did not interfere with patients' daily intellectual function. The computerized battery has methodological advantages (e.g., language options, objectivity, brevity, and ease of use) that make it well-suited for longitudinal studies, for long-term surveillance of substrate reduction therapy as well as for comparisons with other lysosomal storage disorders and other chronic diseases. These preliminary findings should allay fears of cognitive dysfunction due to short-term miglustat therapy.