Effectiveness of methyl-GAG (methylglyoxal-bis[guanylhydrazone]) in patients with advanced malignant lymphoma

We treated 51 patients with advanced malignant lymphoma refractory to conventional therapy with methyl-glyoxal-bis(guanylhydrazone) (methyl- GAG) at doses ranging from 400 to 800 mg/sq m. Therapy was started on a weekly schedule and was switched to every other week in responding patients at the onset of toxicity. Partial responses were observed in 6 of 13 evaluable patients with Hodgkin's disease (46%), 5 of 10 patients with diffuse poorly differentiated lymphocytic lymphoma (50%), 2 of 4 patients with nodular poorly differentiated lymphocytic lymphoma (50%), and 3 of 13 patients with diffuse histiocytic lymphoma (23%). Two of six patients with mycosis fungoides showed objective improvement in cutaneous disease. Toxicity was generally mild and included muscular weakness, myalgia, mucositis, and diarrhea; two patients developed bronchospasm following drug infusions. We conclude that methyl-GAG has major antitumor activity when administered on this schedule to patients with advanced malignant lymphoma. The low degree of toxicity, unique mechanism of action, and minimal myelosuppressive effects suggest that methyl-GAG will prove useful in future trials of combination chemotherapy regimens for the treatment of lymphoma.     

Stress hormone stability: processing of blood samples collected during parabolic flight. A pre-flight comparison of different protocols

OBJECTIVES: Compare different protocols for blood processing to be used during parabolic flights. DESIGN AND METHODS: Measurement of cortisol (COR), prolactin (PRL), adrenocorticotropic hormone (ACTH), epinephrine (EP) and norepinephrine (NOR) concentrations stored at different temperatures and intervals before analysis. RESULTS: COR, PRL and NOR showed no changes in concentration between analysis protocols. ACTH dropped by 60% when not analysed within 24 h. CONCLUSION: A standardised processing protocol that includes a 4-h delay following blood collection is suitable for the assessment of serum stress hormone concentrations.     

Discovery of Marburg virus neutralizing antibodies from virus-naïve human antibody repertoires using large-scale structural predictions

Marburg virus (MARV) disease is lethal, with fatality rates up to 90%. Neutralizing antibodies (Abs) are promising drug candidates to prevent or treat the disease. Current efforts are focused in part on vaccine development to induce such MARV-neutralizing Abs. We analyzed the antibody repertoire from healthy unexposed and previously MARV-infected individuals to assess if naïve repertoires contain suitable precursor antibodies that could become neutralizing with a limited set of somatic mutations. We computationally searched the human Ab variable gene repertoire for predicted structural homologs of the neutralizing Ab MR78 that is specific to the receptor binding site (RBS) of MARV glycoprotein (GP). Eight Ab heavy-chain complementarity determining region 3 (HCDR3) loops from MARV-naïve individuals and one from a previously MARV-infected individual were selected for testing as HCDR3 loop chimeras on the MR78 Ab framework. Three of these chimerized antibodies bound to MARV GP. We then tested a full-length native Ab heavy chain encoding the same 17-residue-long HCDR3 loop that bound to the MARV GP the best among the chimeric Abs tested. Despite only 57% amino acid sequence identity, the Ab from a MARV-naïve donor recognized MARV GP and possessed neutralizing activity against the virus. Crystallization of both chimeric and full-length native heavy chain-containing Abs provided structural insights into the mechanism of binding for these types of Abs. Our work suggests that the MARV GP RBS is a promising candidate for epitope-focused vaccine design to induce neutralizing Abs against MARV.

With the advent of high-throughput immune repertoire sequencing, the number of available human antibody (Ab) sequences is exploding rapidly from thousands to billions. These datasets provide a resource for understanding the natural process of Ab maturation through somatic mutations, quick identification of novel functional Abs, and engineering of improved Abs. Ultimately, such Ab repertoires may provide or add templates for developing epitope-focused (1) and germline-targeting (2, 3) vaccines. While Ab function sometimes can be predicted from sequence homology, often Abs of very different sequence have the same function by virtue of adopting a similar structure. However, despite substantial progress in computational methods of modeling Abs (4, 5) and Ab–antigen interactions (6–10), and the use of high-performance computing, it is still beyond the available computational resources to predict and study the structure of billions of Abs one by one. Therefore, in order to take advantage of the rapidly increasing Ab sequence databases, it is essential to find more effective ways of relating Ab sequence to function.The recently proposed position-specific structure scoring matrix (P3SM) approach is a new computational method specifically designed for rapid screening of large Ab sequence libraries (11, 12). This approach aims to predict whether a given Ab sequence can adopt the desired 3D conformation and thus correctly place critical-for-activity functional groups. This prediction is based on modeling of a small subset of structures using Rosetta (13) followed by evaluation of the compatibility of each of 20 amino acids in each of the analyzed positions with the desired structure and function. The resulting P3SM then can be used for rapid screening of the remaining Ab sequences. The best-scoring candidate sequences are fed back into Rosetta for a detailed energetic analysis and prioritization for experimental validation.The human monoclonal Ab MR78 was isolated previously from a B cell in the peripheral blood of an otherwise healthy individual with a prior history of naturally acquired Marburg virus (MARV) infection (14). A crystal structure of MARV glycoprotein (GP) in complex with MR78 (Protein Data Bank [PDB] ID 5UQY) revealed that the Ab heavy-chain complementarity determining region 3 (HCDR3) contacts the receptor binding domain (RBD) on MARV GP that interacts with the natural receptor on human cells (Niemann–Pick disease, type C1 [NPC1] protein) (15). Here, we applied the P3SM approach to search for structurally homologous Abs to MR78 based on this Ab–antigen cocrystal structure.     

Effects of a novel antiplatelet agent in mural thrombogenesis on collagen-coated glass

A parallel plate flow chamber and an epifluorescence video microscopy system were used to investigate the inhibitory effect of a novel antiplatelet agent (GT-12), a carbamoylpiperidine congener, on surface platelet aggregation and on the kinetics of thrombus growth induced by collagen-coated glass under controlled flow. Both macroscopic and microscopic measurements revealed that increasing concentrations of the drug correspondingly decreased the reaction rate between platelets at the surface, thereby reducing thrombus rate of growth at the surface. Because of decreased platelet/platelet adhesion, there was some embolization of the larger thrombi near the inlet of the reactive surface. In the presence of GT-12, average thrombus size and number of platelets per thrombus were both strikingly lowered. In addition, the net rate of growth of individual thrombi decreased to zero after short exposure times (about 60 seconds), in sharp contrast to controls. In contrast to chlorpromazine, GT-12 was effective in inhibiting platelet aggregation and thrombus rate of growth at relatively low concentrations (less than 100 mumol/L) in whole blood. The drug's effectiveness relative to controls in impeding platelet/platelet interactions was found to increase with decreasing incubation time and increasing perfusion time.     

Comparing the cost-effectiveness of simulation modalities: a case study of peripheral intravenous catheterization training

While the ultimate goal of simulation training is to enhance learning, cost-effectiveness is a critical factor. Research that compares simulation training in terms of educational- and cost-effectiveness will lead to better-informed curricular decisions. Using previously published data we conducted a cost-effectiveness analysis of three simulation-based programs. Medical students (n = 15 per group) practiced in one of three 2-h intravenous catheterization skills training programs: low-fidelity (virtual reality), high-fidelity (mannequin), or progressive (consisting of virtual reality, task trainer, and mannequin simulator). One week later, all performed a transfer test on a hybrid simulation (standardized patient with a task trainer). We used a net benefit regression model to identify the most cost-effective training program via paired comparisons. We also created a cost-effectiveness acceptability curve to visually represent the probability that one program is more cost-effective when compared to its comparator at various ‘willingness-to-pay’ values. We conducted separate analyses for implementation and total costs. The results showed that the progressive program had the highest total cost (p < 0.001) whereas the high-fidelity program had the highest implementation cost (p < 0.001). While the most cost-effective program depended on the decision makers’ willingness-to-pay value, the progressive training program was generally most educationally- and cost-effective. Our analyses suggest that a progressive program that strategically combines simulation modalities provides a cost-effective solution. More generally, we have introduced how a cost-effectiveness analysis may be applied to simulation training; a method that medical educators may use to investment decisions (e.g., purchasing cost-effective and educationally sound simulators).     

Evaluation of atypical human immunodeficiency virus immunoblot reactivity in blood donors

Blood donors reactive by enzyme-linked immunosorbent assay for antibody to the human immunodeficiency virus (HIV) who showed atypical patterns of viral core protein reactivity on Western blot were monitored for several months. Characterization of their antibodies was performed by 1) use of recombinant HIV proteins; 2) determination of cross-reactivity to HTLV-I, HTLV-II, and HTLV-IV: 3) assessment of immune status; and 4) identification of potentially interfering autoantibodies. Nineteen of 20 donors maintained the same HIV antibody reactivity throughout the follow-up period; the other donor became fully antibody-positive. Eighteen of 20 donors' sera showed clear reactivity with HIV recombinant core proteins. Ten of 19 donor samples demonstrated cross-reactivity to HTLV-IV; 3 of these 10 also cross-reacted with HTLV-I. The immune status of all donors was normal, although the medical histories and HLA antibody screens suggested possible autoimmune reactivity in 9 of 18 donors. During follow-up interviews, three donors reported possible risk factors for HIV infection that had not been acknowledged at the time of blood donation. We conclude that exclusion of donors with these atypical serologic test results is warranted while further studies to determine significance are being conducted.