Durability and disinfection of single-use endotracheal tubes following exposure to commonly available medical disinfecting compounds

BACKGROUND

Reusing single-use medical supplies offers a capability enhancement during massive casualty incidents when resupply of medical supplies is unavailable in times of national health care crises. This pilot study determined the feasibility of disinfection of endotracheal tubes with commonly used chemical disinfecting agents.

METHODS

Endotracheal tubes (ETTs) were subjected to either CaviCide, Neutral Disinfectant Cleaner, Cidex, or saline according to the manufacturer's recommended disinfection contact times. Alterations to the polyvinyl chloride (PVC) integrity by disinfecting agents were determined by volume/pressure measurements within the ETT cuff. To test the disinfection rate, ETTs were inoculated with Staphylococcus Aureus and subjected to experimental disinfection protocol.

FINDINGS

There were no significant alterations to ETT tracheal cuff function and mixed results in disinfection among ETTs. ETTs bacterial culture data presented possible contamination among the groups.

DISCUSSION

These data support the feasibility of single-use ETT reuse as a last resort while making every attempt and effort to follow established protocols to minimize harm to the patient.

Seasonal variation in a diverse beetle assemblage along two elevational gradients in the Australian Wet Tropics

Altered abiotic conditions resulting from human-induced climate change are already driving changes in the spatial and temporal distributions of many organisms. For insects, how species are distributed across elevations is relatively well known, but data on their seasonality at different elevations are lacking. Here we show seasonal variation in beetle abundance and species richness along two spatially-distinct elevational transects (350-1000 m and 100-1000 m asl) in the rainforests of northern Australia. Temperature was the best predictor of temporal abundance and species richness patterns, while rainfall had little influence. Elevation had little effect on seasonal changes in abundance or diversity. Adults of most beetle species exhibited long season-lengths (>6 months of the year) with distinct peaks in abundance during the summer wet-season. We found evidence of phenotypic variation among the more widespread species, with seasonal peaks in abundance often not coinciding across elevations or transects. Due to the wide elevational range of most species, and the lack of consistency in the seasonality of wide-spread individual species, we suggest that many beetles inhabiting the low to mid-elevation mountains in the Wet Tropics, and potentially other tropical rainforests, are not as vulnerable to extinction due to climate change as many other organisms.

Polymorphisms of the cannabinoid 1 receptor gene and cognitive impairment in multiple sclerosis

Cognitive impairment occurs in 45—65% of multiple sclerosis (MS) patients. The cannabinoid system may potentially be neuroprotective in MS. We examined the relationship between polymorphisms of the CNR1 gene and neuropsychological outcome in MS using a test and confirmatory sample of patients. One hundred and ninety-four MS patients were assessed over five key areas of neuropsychological function, which are most commonly impaired in MS. The first 97 patients formed the test sample. A further confirmatory sample of 97 patients was used to test association found in the test sample. The schedule included: Wisconsin card sorting test 64 version, Rey auditory verbal learning task immediate and delayed scores, controlled oral word association task, judgement of line orientation and symbol digit modalities task. Three single nucleotide polymorphisms (SNPs) were typed within the CNR1 gene.

For the overall neuropsychological assessment score we used a multiple linear regression model with selected covariates to show that subjects with the AA genotype of the SNP RS1049353 were more impaired (mean -2.47, SD 5.75, P = 0.008, Bonferroni corrected P = 0.024) than the other subjects (mean 0.24, SD 4.24). This was not confirmed when the association was retested in the confirmatory sample.

No associations were identified between these CNR1 variants and cognitive impairment in MS. Multiple Sclerosis 2008; 14: 177—182. http://msj.sagepub.com

Peripheral neuropathies in Waldenström's macroglobulinaemia

OBJECTIVE

We sought to determine the prevalence, clinical features, and laboratory characteristics of polyneuropathies in Waldenström's macroglobulinaemia (WM), a malignant bone marrow disorder with lymphocytes that produce monoclonal IgM.

METHODS

We prospectively studied 119 patients with WM and 58 controls. Medical history was taken, and neurological examinations, electrodiagnostic tests, and serum studies were performed by different examiners who were blinded to results except the diagnosis of WM.

RESULTS

Polyneuropathy symptoms, including discomfort and sensory loss in the legs, occurred more frequently (p<0.001) in patients with WM (47%) than in controls (9%). Patients with WM had 35% lower quantitative vibration scores, and more frequent pin loss (3.4 times) and gait disorders (5.5 times) than controls (all p<0.001). Patients with IgM binding to sulphatide (5% of WM) had sensory axon loss; those with IgM binding to myelin associated glycoprotein (MAG) (4% of WM) had sensorimotor axon loss and demyelination. Patients with WM with IgM binding to sulphatide (p<0.005) or MAG (p<0.001) had more severe sensory axon loss than other patients with WM. Demyelination occurred in 4% of patients with WM with no IgM binding to MAG. Age related reductions in vibration sense and sural SNAP amplitudes were similar ( approximately 30%) in WM and controls.

CONCLUSIONS

Peripheral nerve symptoms and signs occur more frequently in patients with WM than controls, involve sensory modalities, and are often associated with gait disorders. IgM binding to MAG or sulphatide is associated with a further increase in the frequency and severity of peripheral nerve involvement. Age related changes, similar to those in controls, add to the degree of reduced nerve function in patients with WM.

Monoclonal antibodies in the prehybridoma era: a brief historical perspective and personal reminiscence

Emil von Behring, an immunologist, received the first Nobel Prize in Physiology or Medicine in 1901 for his studies on serum therapy of diphtheria. Seventeen Nobel Prizes have been awarded to scientists for their work in immunology and related disciplines. E. Metchnikoff and P. Ehrlich were pioneers who became associated with cellular and humoral theories of immunity, respectively. Almroth Wright described opsonins and was a vigorous advocate of vaccine therapy for bacterial diseases. He was an influential scientist and mentor who served as the model for Bernard Shaw's play, The Doctor's Dilemma. Immunochemistry developed through the work of K. Landsteiner, M. Heidelberger, E. Kabat, and many others. At mid-20th century, cell-selection theories of antibody formation championed by N. Jerne and F.M. Burnet shifted the field from a chemical to a biological orientation. Myeloma immunoglobulins, Bence Jones proteins, and monoclonal macroglobulins from patients and mice played a central role in elucidation of normal immunoglobulin structure, genetics, synthesis, and metabolism. By the late 1960s, antibody activity in some human myeloma and Waldenström macroglobulin paraproteins had been documented. Subsequently, other human paraproteins were shown to have antigen-binding properties, principally to auto- or bacterial antigens. The development of hybridoma technology by G. Köhler and C. Milstein revolutionized immunology after 1975. These investigators demonstrated that antibody-producing cells of virtually any desired specificity could be fused with a myeloma cell line, the result being unlimited amounts of homogeneous (monoclonal) antibodies carrying that specificity. Monoclonal antibodies have been shown to have efficacy in cancer therapy, particularly in patients with lymphoma and breast cancer. It is likely that this approach, alone and in combination with other modalities, will prove useful for patients with additional types of malignancies.

Hepatic failure as the presenting manifestation of malignant lymphoma

Fulminant hepatic failure carries a high mortality regardless of etiology. Liver transplantation may be lifesaving. Hepatic invasion by malignant lymphoma is a rare cause of liver failure, but one that is potentially responsive to treatment. Lymphoma (non-Hodgkin's or Hodgkin's) should be included in the differential diagnosis of fulminant hepatic failure so that liver transplantation is avoided and appropriate therapy can be instituted. The findings and clinical course of 4 patients with liver failure due to hepatic lymphoma, who were referred to our institution for liver transplant evaluation, are presented and discussed. Medical records, imaging studies, and histological material were examined. Review of the literature revealed less than 40 cases of lymphoma presenting as fulminant hepatic failure. The diagnosis of malignant lymphoma may be difficult. The presenting symptoms and signs are indistinguishable from other causes of fulminant hepatic failure. Early liver biopsy with adequate tissue and immunologic studies is mandatory for diagnosis. This condition may be reversible and may respond to chemotherapy if the diagnosis is made prior to multiorgan system failure. The presence of malignant lymphoma is considered a contraindication to liver transplantation, although firm data are lacking.

NMR solution structure and backbone dynamics of the CC chemokine eotaxin-3

Eotaxin-3 is one of three related chemokines that specifically activate chemokine receptor CCR3. We report the 3D structure and backbone dynamics of eotaxin-3 determined by NMR spectroscopy. Eotaxin-3 is monomeric under the conditions in this study and consists of an unstructured N-terminus before the first two conserved cysteine residues, an irregularly structured N-loop following the second conserved cysteine, a single turn of 3(10)-helix, a three-stranded antiparallel beta-sheet, an alpha-helix, and an unstructured C-terminal tail. As in other chemokines, the alpha-helix packs against one face of the beta-sheet. The average backbone and heavy atom rmsd values of the 20 structures (residues 9-65) are 0.44 and 1.01 A, respectively. A comparison between the structures of eotaxin-3 and related chemokines suggests that the electrostatic potential in the vicinity of a surface groove and the structure of the beta2-beta3 turn may be important for maintaining receptor specificity. The backbone dynamics of eotaxin-3 were determined from 15N NMR relaxation data using the extended model free dynamics formalism. Large amplitude motions on the picosecond to nanosecond time scale were observed in both termini and in some residues in the N-loop, the beta1-beta2 turn, and the beta3 strand; the location of these residues suggests a possible role for dynamics in receptor binding and activation. In contrast to eotaxin, eotaxin-3 exhibits no substantial mobility on the microsecond to millisecond time scale.

NMR relaxation studies of the role of conformational entropy in protein stability and ligand binding

Recent advances in the measurement and analysis of protein NMR relaxation data have made it possible to characterize the dynamical properties of many backbone and side chain groups. With certain caveats, changes in flexibility that occur upon ligand binding, mutation, or changes in sample conditions can be interpreted in terms of contributions to conformational entropy. Backbone and side chain flexibility can either decrease or increase upon ligand binding. Decreases are often associated with "enthalpy-entropy compensation" and "induced fit" binding, whereas increases in conformational entropy can contribute to stabilization of complexes. In certain cases, conformational entropy appears to play a role in cooperative binding and enzyme catalysis. In addition, variations in conformational entropy and heat capacity may both be important in stabilizing the folded structures of proteins.

Identification of receptor binding and activation determinants in the N-terminal and N-loop regions of the CC chemokine eotaxin

Eotaxin is a CC chemokine that specifically activates the receptor CCR3 causing accumulation of eosinophils in allergic diseases and parasitic infections. Twelve amino acid residues in the N-terminal (residues 1-8) and N-loop (residues 11-20) regions of eotaxin have been individually mutated to alanine, and the ability of the mutants to bind and activate CCR3 has been determined in cell-based assays. The alanine mutants at positions Thr(7), Asn(12), Leu(13), and Leu(20) show near wild type binding affinity and activity. The mutants T8A, N15A, and K17A have near wild type binding affinity for CCR3 but reduced receptor activation. A third class of mutants, S4A, V5A, R16A, and I18A, display significantly perturbed binding affinity for CCR3 while retaining the ability to activate or partially activate the receptor. Finally, the mutant Phe(11) has little detectable activity and 20-fold reduced binding affinity relative to wild type eotaxin, the most dramatic effect observed in both assays but less dramatic than the effect of mutating the corresponding residue in some other chemokines. Taken together, the results indicate that residues contributing to receptor binding affinity and those required for triggering receptor activation are distributed throughout the N-terminal and N-loop regions. This conclusion is in contrast to the separation of binding and activation functions between N-loop and N-terminal regions, respectively, that has been observed previously for some other chemokines.

Growth-inhibitory effects of CD40 ligand (CD154) and its endogenous expression in human breast cancer

CD40 binding produces multifaceted growth signals in normal and malignant B cells, whereas its physiological role is less well characterized in epithelial cancers. We examined the growth outcome of CD40 ligation in human breast cancer cells, using CD40+ (T47D and BT-20) and CD40-negative (MCF-7, ZR-75-1) cell lines as defined by flow cytometric analysis, immunohistochemistry, and reverse transcription-PCR. Treatment with the soluble recombinant CD40 ligand (CD40L) molecules gp39 or CD40L-trimer significantly reduced [3H]thymidine uptake in BT-20 and T47D cells by up to 40%, but did not affect the growth of CD40-negative MCF-7 or ZR-75-1 cells. Similarly, significant growth inhibition was observed after co-incubation with CD40L-transfected murine L cells (55.0 +/- 8.9%, P < 0.001) that express membrane CD40L constitutively, or with paraformaldehyde-fixed, CD3+ CD40L+ PBLs from three different HLA-mismatched donors (39.7 +/- 3.7%, P < 0.01). Untransfected L cells and non-CD40L-expressing lymphocytes did not produce significant growth inhibition. The in vivo antitumorigenic effects of CD40L were examined using a s.c. severe combined immunodeficient-hu xenograft model. Pretreatment with two different soluble recombinant CD40L constructs (CD40L and gp39) produced similar xenograft growth-inhibitory effects [67 +/- 24% (n = 4), and 65 +/- 14% (n = 8) inhibition, respectively], which were reversed by co-treatment with the CD40L-neutralizing antibody LL48. In vitro analysis indicated that CD40L-induced growth inhibition was accompanied by apoptotic events including cell shrinkage, rounding, and detachment from the adherent T47D culture monolayer. Thirty-one and 27% of gp39-treated T47D and BT-20 cells underwent apoptosis, respectively, as compared with 56 and 65% from the same cell lines after treatment with the Fas agonistic antibody CH-11. An up-regulation of the proapoptotic protein Bax in T47D and BT-20 cells was observed, which indicated that this Bcl-2 family member may contribute to this growth-inhibitory effect. To explore the clinical relevance of CD40L-CD40 interaction, retrospective immunohistochemical analysis was carried to characterize in situ CD40- and CD40L-expression in breast cancer patient biopsies. All of the infiltrating ductal (5 of 5 cases tested) and lobular (4 of 4 cases) breast carcinomas, carcinomas in situ (6 of 6 cases), and mucinous carcinoma tested (1 case) expressed CD40. Varying proportions of tumor cells also expressed CD40L in the majority of infiltrating ductal (3 of 5 cases) and lobular (3 of 4 cases) carcinomas, and carcinomas in situ (4 of 6 cases), as determined by immunohistochemistry and validated by RT-PCR detection of the CD40L message in only CD40L positive-staining cases. Tumor infiltrating mononuclear cells from infiltrating carcinomas and carcinomas in situ expressed CD40 (10 of 10 cases), but less commonly CD40L (1 case of infiltrating lobular carcinoma, 2 cases of carcinoma in situ). Our findings indicate that the CD40 signaling pathway is active in human breast carcinoma cells. However, tumor-infiltrating lymphocytes from primary tumor tissues may be limited in their capacity to directly modulate tumor growth through the CD40L-CD40 loop.

Characterization of binding between the chemokine eotaxin and peptides derived from the chemokine receptor CCR3

The CC chemokine eotaxin plays a predominant role in eosinophil trafficking in vivo by specifically activating the chemokine receptor CCR3. We have screened a series of synthetic peptides corresponding to extracellular regions of CCR3 for their ability to bind eotaxin. A peptide corresponding to the N terminus of CCR3 (CCR3-(1-35)) bound to eotaxin with a dissociation constant of 80 +/- 38 micrometer. However, linear or cyclic peptides derived from the first and third extracellular loops of CCR3 did not bind to eotaxin. Linear and cyclic peptides derived from the second extracellular loop precipitated upon addition of eotaxin. (1)H-(15)N correlation NMR spectroscopy indicated that an extended groove in the eotaxin surface, whose edges are defined by the N-loop, 3(10)-helical turn, and beta(2)-beta(3) hairpin, is the most likely binding surface for CCR3-(1-35). NMR assignments for CCR3-(1-35) were obtained using two-dimensional and three-dimensional homonuclear NMR experiments. (15)N-Filtered TOCSY spectra indicated that the central region of CCR3-(1-35), surrounding the DDYY sequence, is involved in the interaction with eotaxin. This was supported by the observation that a truncated N-terminal peptide (CCR3-(8-23)) binds to eotaxin with a dissociation constant of 136 +/- 23 micrometer, only slightly weaker than the full-length N-terminal peptide. Taken together with previous studies, these results suggest that interactions between the N-loop/beta(3) regions of chemokines and the N-terminal regions of their receptors may be a conserved feature of chemokine-receptor complexes across the CC, CXC, and C chemokine subfamilies. However, the low affinity of the interactions observed in these studies suggests the existence of additional binding regions in both the chemokines and the receptors.

NMR solution structure and receptor peptide binding of the CC chemokine eotaxin-2

The human CC chemokine eotaxin-2 is a specific agonist for the chemokine receptor CCR3 and may play a role in the recruitment of eosinophils in allergic diseases and parasitic infections. We report the solution structure of eotaxin-2 determined using heteronuclear and triple resonance NMR methods. A family of 20 structures was calculated by hybrid distance geometry-simulated annealing from 854 NOE distance restraints, 48 dihedral angle restraints, and 12 hydrogen bond restraints. The structure of eotaxin-2 (73 amino acid residues) consists of a helical turn (residues 17-20) followed by a 3-stranded antiparallel beta-sheet (residues 22-26, 37-41, and 44-49) and an alpha-helix (residues 54-66). The N-loop (residues 9-16) is packed against both the sheet and the helix with the two conserved disulfide bonds tethering the N-terminal/N-loop region to the beta-sheet. The average backbone and heavy atom rmsd values of the 20 structures (residues 7-66) are 0.52 and 1.13 A, respectively. A linear peptide corresponding to the N-terminal region of CCR3 binds to eotaxin-2, inducing concentration-dependent chemical shift changes or line broadening of many residues. The distribution of these residues suggests that the peptide binds into an extended groove located at the interface between the N-loop and the beta2-beta3 hairpin. The receptor peptide may also interact with the N-terminus of the chemokine and part of the alpha-helix. Comparison of the eotaxin-2 structure with those of related chemokines indicates several structural features that may contribute to receptor specificity.

The role of backbone conformational heat capacity in protein stability: temperature dependent dynamics of the B1 domain of Streptococcal protein G

The contributions of backbone NH group dynamics to the conformational heat capacity of the B1 domain of Streptococcal protein G have been estimated from the temperature dependence of 15N NMR-derived order parameters. Longitudinal (R1) and transverse (R2) relaxation rates, transverse cross-relaxation rates (eta(xy)), and steady state [1H]-15N nuclear Overhauser effects were measured at temperatures of 0, 10, 20, 30, 40, and 50 degrees C for 89-100% of the backbone secondary amide nitrogen nuclei in the B1 domain. The ratio R2/eta(xy) was used to identify nuclei for which conformational exchange makes a significant contribution to R2. Relaxation data were fit to the extended model-free dynamics formalism, incorporating an axially symmetric molecular rotational diffusion tensor. The temperature dependence of the order parameter (S2) was used to calculate the contribution of each NH group to conformational heat capacity (Cp) and a characteristic temperature (T*), representing the density of conformational energy states accessible to each NH group. The heat capacities of the secondary structure regions of the B1 domain are significantly higher than those of comparable regions of other proteins, whereas the heat capacities of less structured regions are similar to those in other proteins. The higher local heat capacities are estimated to contribute up to approximately 0.8 kJ/mol K to the total heat capacity of the B1 domain, without which the denaturation temperature would be approximately 9 degrees C lower (78 degrees C rather than 87 degrees C). Thus, variation of backbone conformational heat capacity of native proteins may be a novel mechanism that contributes to high temperature stabilization of proteins.

Serologic prevalence of antibody to human herpesvirus type 8 in patients with various monoclonal gammopathies

Both viral and serologic studies have consistently shown an association of human herpesvirus type 8 (HHV-8) with Kaposi's sarcoma, primary effusion lymphoma, and Castleman's disease. The presence of HHV-8 DNA in patients with myeloma has been reported by some investigators but not substantiated by others. In addition, variable results have been obtained with serologic studies for HHV-8 in patients with myeloma and certain other monoclonal gammopathies (MG). We tested 238 coded serum or plasma samples from 96 patients with various MG for antibodies to lytic and latent HHV-8 antigens by indirect immunofluorescence. Thirty-four of 96 (35%) patients were positive for the lytic antibody, but none were positive for the latent antibody. Patients with kappa or lambda light chain myeloma were often positive for the lytic antibody when compared to patients with IgG or IgA myeloma (8 of 11 [73%] vs. 12 of 38 [32%], P = 0.033). The patients with light chain myeloma also were more likely to be positive when compared to patients with Waldenström's macroglobulinemia (WM) (4 of 15 [27%], P = 0.045) or AL amyloidosis (4 of 13 [31%], P = 0.047). Four of 9 (44%) patients with monoclonal gammopathy of undetermined significance (MGUS) were positive. However, 4 other patients who progressed from MGUS to myeloma were negative. Subgroup analysis of MG may help clarify the role of HHV-8 in these disorders.

CD40 ligand-induced apoptosis is Fas-independent in human multiple myeloma cells

We and others previously demonstrated that human multiple myeloma (MM) cells express CD40 and have an active CD40-growth regulatory pathway. This study characterizes the growth outcome of soluble (gp39) or membrane-bound recombinant human CD40-ligand (rCD40L) and its relationship with Fas-dependent apoptosis. Contrary to the moderate growth-stimulatory effect of the CD40-MAb G28.5, gp39 inhibited 3H-thymidine uptake of the plasma dyscrasia lines ARH-77, U266, and HS-Sultan in a dose-dependent fashion by up to 82%. By comparison, RPMI 8226 cells were resistant to CD40L-growth modulation, which may be attributable to a single base substitution (TCA-->TTA, serine-->leucine) at the 3rd cysteine-rich extramembrane region of CD40. Gp39 similarly reduced myeloma clonogenic colony (MCC) formation in patient primary bone marrow cultures by 50% (40-76%; n=6). Studies using transfectant L cells that constitutively expressed CD40L showed that membrane-bound CD40L inhibited the growth of ARH-77, U266, and HS-Sultan cells (66%, 63%, and 32%, respectively), whereas untransfected L cells did not. Growth inhibition by gp39 or CD40L+ L cells was neutralized by coincubation with the CD40L antibodies 5c8 or LL48. CD40L-treatment increased apoptotic activity of MM cells, as defined by oligonucleosomal DNA fragmentation and an increased binding to annexin V (16-28%). All three untreated CD40-responsive MM lines expressed the Fas/Apo-1/CD95 antigen (65-92% CD95+). However, only ARH-77 cells responded to the growth inhibitory effect of the CD95-agonistic antibody CH-11. CD95 expression was not affected significantly by gp39 treatment, and growth inhibition by CH-11 was additive to gp39 (from 42% to 64% decrease in 3H-thmidine uptake). Conversely, the CD95 antagonist antibody ZB4 reversed the Fas-dependent growth inhibitory process but did not significantly alter gp39-mediated growth outcome. Gp39 treatment lowered the expression of TNFR-associated factors TRAF4 and TRAF6 by 38% and 32%, respectively, whereas detectable levels of TRAF1,2,3, and 5 levels remained unchanged. Our observations indicate that the CD40L-binding inhibits human MM cell growth and increases its apoptotic activity. This growth inhibitory effect corresponds to lower levels of cytoplasmic TRAF signaling elements, and appears independent of the Fas-signaling pathway. CD40 receptor mutation may lead to unresponsiveness to CD40 growth modulation in multiple myeloma cells.

Relationships between protein structure and dynamics from a database of NMR-derived backbone order parameters

The amplitude of protein backbone NH group motions on a time-scale faster than molecular tumbling may be determined by analysis of (15)N NMR relaxation data according to the Lipari-Szabo model free formalism. An internet-accessible database has been compiled containing 1855 order parameters from 20 independent NMR relaxation studies on proteins whose three-dimensional structures are known. A series of statistical analyses has been performed to identify relationships between the structural features and backbone dynamics of these proteins. Comparison of average order parameters for different amino acid types indicates that amino acids with small side-chains tend to have greater backbone flexibility than those with large side-chains. In addition, the motions of a given NH group are also related to the sizes of the neighboring amino acids in the primary sequence. The secondary structural environment appears to influence backbone dynamics relatively weakly, with only subtle differences between the order parameter distributions of loop structures and regular hydrogen bonded secondary structure elements. However, NH groups near helix termini are more mobile on average than those in the central regions of helices. Tertiary structure influences are also relatively weak but in the expected direction, with more exposed residues being more flexible on average than residues that are relatively inaccessible to solvent.

Increased protein backbone conformational entropy upon hydrophobic ligand binding

For complexes between proteins and very small hydrophobic ligands, hydrophobic effects alone may be insufficient to outweigh the unfavorable entropic terms resulting from bimolecular association. NMR relaxation experiments indicate that the backbone flexibility of mouse major urinary protein increases upon binding the hydrophobic mouse pheromone 2-sec-butyl-4,5-dihydrothiazole. The associated increase in backbone conformational entropy of the protein appears to make a substantial contribution toward stabilization of the protein-pheromone complex. This term is likely comparable in magnitude to other important free energy contributions to binding and may represent a general mechanism to promote binding of very small ligands to macromolecules.

Backbone dynamics of the human CC-chemokine eotaxin

Eotaxin is a CC chemokine with potent chemoattractant activity towards eosinophils. 15N NMR relaxation data have been used to characterize the backbone dynamics of recombinant human cotaxin. 15N longitudinal (R1) and transverse (R2) auto relaxation rates, heteronuclear ¿1H¿-15N steady-state NOEs, and transverse cross-relaxation rates (eta xy) were obtained at 30 degrees C for all resolved backbone secondary amide groups using 1H-detected two-dimensional NMR experiments. Ratios of transverse auto and cross relaxation rates were used to identify NH groups influenced by slow conformational rearrangement. Relaxation data were fit to the extended model free dynamics formalism, yielding parameters describing axially symmetric molecular rotational diffusion and the internal dynamics of each NH group. The molecular rotational correlation time (tau m) is 5.09 +/- 0.02 ns, indicating that eotaxin exists predominantly as a monomer under the conditions of the NMR study. The ratio of diffusion rates about unique and perpendicular axes (D parallel/D perpendicular) is 0.81 +/- 0.02. Residues with large amplitudes of subnanosecond motion are clustered in the N-terminal region (residues 1-19), the C-terminus (residues 68-73) and the loop connecting the first two beta-strands (residues 30-37). N-terminal flexibility appears to be conserved throughout the chemokine family and may have implications for the mechanism of chemokine receptor activation. Residues exhibiting significant dynamics on the microsecond-millisecond time scale are located close to the two conserved disulfide bonds, suggesting that these motions may be coupled to disulfide bond isomerization.

NMR mapping of the recombinant mouse major urinary protein I binding site occupied by the pheromone 2-sec-butyl-4,5-dihydrothiazole

The interactions between the mouse major urinary protein isoform MUP-I and the pheromone 2-sec-butyl-4,5-dihydrothiazole have been characterized in solution. (15)N-labeled and (15)N, (13)C-doubly-labeled recombinant MUP-I were produced in a bacterial expression system and purified to homogeneity. Racemic 2-sec-butyl-4, 5-dihydrothiazole was produced synthetically. An equilibrium diffusion assay and NMR titration revealed that both enantiomers of the pheromone bind to the recombinant protein with a stoichiometry of 1 equiv of protein to 1 equiv of racemic pheromone. A micromolar dissociation constant and slow-exchange regime dissociation kinetics were determined for the pheromone-protein complex. (1)H, (15)N, and (13)C chemical shifts of MUP-I were assigned using triple resonance and (15)N-correlated 3D NMR experiments. Changes in protein (1)H(N) and (15)N(H) chemical shifts upon addition of pheromone were used to identify the ligand binding site. Several amide signals, corresponding to residues on one side of the binding site, were split into two peaks in the saturated protein-ligand complex. Similarly, two overlapping ligand spin systems were present in isotope-filtered NMR spectra of labeled protein bound to unlabeled pheromone. The two sets of peaks were attributed to the two possible chiralities of the pheromone. Intermolecular NOEs indicated that the orientation of the pheromone in the MUP-I binding cavity is opposite to that modeled in a previous X-ray structure.

Alpha-heavy chain disease, Mediterranean lymphoma, and immunoproliferative small intestinal disease: a review of clinicopathological features, pathogenesis, and differential diagnosis

There are a number of clinical syndromes associated with chronic diarrhea, malabsorption, and lymphoplasmacytic proliferation of the small intestine. In Middle-Eastern and Mediterranean countries immunoproliferative small intestinal disease is endemic, whereas in other parts of the world (including Northwestern Europe and North America) celiac sprue, and other sprue-like syndromes refractory to dietary gluten withdrawal, predominate. All of these syndromes appear to involve chronic stimulation of intestinal mucosa-associated lymphoid tissue and are associated with a heightened risk of malignant transformation. The clinicopathological features of these diseases, and distinction of the Middle Eastern syndromes from those more common in the Western hemisphere, have been reviewed.

Delphi-panel analysis of appropriateness of high-dose therapy and bone marrow autotransplants in newly diagnosed multiple myeloma

There is controversy whether high-dose therapy and a bone marrow autotransplant or conventional chemotherapy is a better treatment for newly diagnosed multiple myeloma. Data from 1 comparative study and 1 randomized trial provide insufficient subject-level data to advise specific people whether to have an autotransplant. We analyzed appropriate use of high-dose therapy and bone marrow autotransplants in people with newly diagnosed, multiple myeloma using a modified Delphi-panel group judgment process. The panel consisted of 9 myeloma experts from diverse geographic sites and practice settings who reviewed Boolean MEDLINE searches of multiple myeloma and chemotherapy or autotransplants. The panel rated a metric of 64 clinical setting developed by permuting age, performance score, disease-stage and disease-related prognostic variables and response to initial therapy. Each panelist rated appropriateness of high-dose therapy and an autotransplant versus conventional-dose chemotherapy on a 9-point ordinal scale (1, most inappropriate, 9, most appropriate). An appropriateness index was developed based on median rating and amount of disagreement. Relationship of appropriateness indices to the permuted clinical variables was considered by analysis of variance and recursive partitioning. Autotransplants were rated appropriate in persons <55 years old with stage 3 disease and a complete or partial response or stable disease after initial chemotherapy, inappropriate in persons with stage 1 or 2 disease, a performance score <70% and a complete or partial response or stable disease after initial chemotherapy and uncertain in all other settings.

Active monomeric and dimeric forms of Pseudomonas putida glyoxalase I: evidence for 3D domain swapping

3D domain swapping of proteins involves the interconversion of a monomer containing a single domain-domain interface and a 2-fold symmetrical dimer containing two equivalent intermolecular interfaces. Human glyoxalase I has the structure of a domain-swapped dimer [Cameron, A. D., Olin, B., Ridderström, M., Mannervik, B., and Jones, T. A. (1997) EMBO J. 16, 3386-3395] but Pseudomonas putida glyoxalase I has been reported to be monomeric [Rhee, H.-I., Murata, K., and Kimura, A. (1986) Biochem. Biophys. Res. Commun. 141, 993-999]. We show here that recombinant P. putida glyoxalase I is an active dimer (kcat approximately 500 +/- 100 s-1; KM approximately 0.4 +/- 0.2 mM) with two zinc ions per dimer. The zinc is required for structure and function. However, treatment of the dimer with glutathione yields an active monomer (kcat approximately 115 +/- 40 s-1; KM approximately 1.4 +/- 0.4 mM) containing a single zinc ion. The monomer is metastable and slowly reverts to the active dimer in the absence of glutathione. Thus, glyoxalase I appears to be a novel example of a single protein able to exist in two alternative domain-swapped forms. It is unique among domain-swapped proteins in that the active site and an essential metal binding site are apparently disassembled and reassembled by the process of domain swapping. Furthermore, it is the only example to date in which 3D domain swapping can be regulated by a small organic ligand.

The mechanism of an inhibitory antibody on TF-initiated blood coagulation revealed by the crystal structures of human tissue factor, Fab 5G9 and TF.G9 complex

The tissue factor (TF)-initiated blood coagulation protease cascade can be greatly inhibited in vivo by a potent anti-human-TF monoclonal antibody, 5G9. This antibody binds the carboxyl module of the extracellular domain of TF with a nanomolar binding constant and inhibits the formation of the TF.VIIa.X ternary initiation complex. We have determined the crystal structures of the extra-cellular modules of human TF, Fab 5G9, and their complex (TF.5G9) to 2.4 A, 2. 5 A, and 3.0 A, respectively, and measured the apparent inhibition constants of 5G9 on a panel of TF mutants. In our unliganded TF structure, a 7 degrees change in the relative orientation between the D1 and D2 modules was observed when compared with other published TF structures. Comparison of the free and bound Fab 5G9 indicates that small segmental and side chain variation of the antibody complementarity determining regions occurred on complexation with TF. The antibody-antigen recognition involves 18 TF antigen residues and 19 Fab residues from six CDR with one of the largest buried surface areas seen to date. A combination of structural and mutagenesis data indicate that Tyr156, Lys169, Arg200, and Lys201 play the major role in the antibody recognition. The TF. 5G9 structure provides insights into the mechanism by which the antibody 5G9 inhibits formation of the TF.VIIa.X ternary complex.

Successful treatment of chronic severe neutropenia with weekly recombinant granulocyte-colony stimulating factor

Daily treatment for symptomatic chronic neutropenia with recombinant granulocyte-colony stimulating factor (rhG-CSF) filgrastim is costly and sometimes causes neutrophillia. We report the use of weekly filgrastim in a 40-year-old man with life-long symptomatic neutropenia. Baseline neutrophil counts were < 1 x 10(9)/l 60% of the time, and fell below 0.5 x 10(9)/l for 7d periods every 22 d. Following 1 year of weekly filgrastim treatment, the absolute neutrophil count was maintained > 1 x 10(9)/l (averaging 2 x 10(9)/l) and the frequency and severity of symptoms were reduced by 85%. Therefore the benefits of filgrastim for the treatment of at least one form of chronic severe neutropenia can be derived from weekly rather than daily doses.

Decreases in levels of serum fibronectin predict the severity of vascular leak syndrome in patients treated with ricin A chain-containing immunotoxins

The major dose-limiting adverse effect of ricin A chain-containing immunotoxin (IT) therapy is vascular leak syndrome (VLS). Since plasma fibronectin (Fn) plays a role in maintaining microcirculatory integrity and since the gradient between plasma and tissue Fn can be altered in various pathological situations, we determined whether the administration of IT-ricin A chain to patients resulted in changes in the levels of serum Fn and, if so, whether these changes correlated with the severity of VLS. We also measured the serum levels of tumor necrosis factor alpha (TNFalpha), a proinflammatory cytokine which has been implicated in tissue damage and in interleukin 2-mediated VLS. Our results indicate that the most severe manifestations of VLS were associated with the highest pretreatment levels of Fn, the largest decreases in Fn immediately after starting IT therapy, increases in the levels of serum TNFalpha, higher concentrations of circulating IT, and the lowest numbers of circulating tumor cells. These parameters should, therefore, be useful for predicting which patients will have severe VLS.

Validation of an enzymatic total magnesium determination based on activation of modified isocitrate dehydrogenase

We have evaluated an enzymatic assay for the determination of Mg in serum, based on the activation of a chemically modified form of isocitrate dehydrogenase by Mg2+. In the presence of potassium isocitrate and NADP+, NADPH, which absorbs light at 340 nm, is produced, and its increase is proportional to Mg2+ in the sample. We have shown linearity to at least 5 mmol/L Mg and good precision by within-run CVs between 1.4% and 3.5% and day to day CVs between 3.2% and 5.4%. The method (y) is accurate, comparing well with the xylidyl blue method (x), with a Deming regression of y = 0.930x - 0.063 (r = 0.98, S(y/x) = 0.019), and with atomic absorption spectrophotometry (x), with a Deming regression of y = 0.932x - 0.016 (r = 0.97, S(y/x) = 0.023), and shows no interference from common endogenous compounds in blood and various metal ions except for visibly hemolyzed samples. A rapid assay, with reagents that are stable for at least 30 days at 4 degrees C and requiring no prior preparation, it is simple to use and suitable for adaptation onto automated chemistry analyzers.

Validation of an enzymatic total magnesium determination based on activation of modified isocitrate dehydrogenase

We have evaluated an enzymatic assay for the determination of Mg in serum, based on the activation of a chemically modified form of isocitrate dehydrogenase by Mg2+. In the presence of potassium isocitrate and NADP+, NADPH, which absorbs light at 340 nm, is produced, and its increase is proportional to Mg2+ in the sample. We have shown linearity to at least 5 mmol/L Mg and good precision by within-run CVs between 1.4% and 3.5% and day to day CVs between 3.2% and 5.4%. The method (y) is accurate, comparing well with the xylidyl blue method (x), with a Deming regression of y = 0.930x - 0.063 (r = 0.98, S(y/x) = 0.019), and with atomic absorption spectrophotometry (x), with a Deming regression of y = 0.932x - 0.016 (r = 0.97, S(y/x) = 0.023), and shows no interference from common endogenous compounds in blood and various metal ions except for visibly hemolyzed samples. A rapid assay, with reagents that are stable for at least 30 days at 4 degrees C and requiring no prior preparation, it is simple to use and suitable for adaptation onto automated chemistry analyzers.

A phase I study of bolus versus continuous infusion of the anti-CD19 immunotoxin, IgG-HD37-dgA, in patients with B-cell lymphoma

IgG-HD37-SMPT-dgA is a deglycosylated ricin A chain (dgA)-containing immunotoxin (IT) prepared by conjugating the monoclonal murine (MoAb) anti-CD19 antibody, HD37, to dgA using the heterobifunctional hindered disulfide linker, N-succinimidyl-oxycarbonyl-alpha-methyl-alpha-(2-pyridyldithio) toluene (SMPT). In this report, we have used two regimens for the administration of IgG-HD37-SMPT-dgA to patients with non-Hodgkin's lymphoma (NHL) in two concomitant phase I trials. One trial examined four intermittent bolus infusions administered at 48-hour intervals. The other studied a continuous infusion (CI) administered over the same 8-day period. In the intermittent bolus regimen, the maximum tolerated dose (MTD) was 16 mg/m2/8 d and the dose-limiting toxicity (DLT) consisted of vascular leak syndrome (VLS), aphasia, and evidence of rhabdomyolysis encountered at 24 mg/m2/8 d. Using the CI regimen, the MTD was defined by VLS at 19.2 mg/m2/8 d. At the MTD of both regimens, a novel toxicity, consisting of acrocyanosis with reversible superficial distal digital skin necrosis in the absence of overt evidence of systemic vasculitis, occurred in 3 patients. Of 23 evaluable patients on the bolus schedule, there was 1 persisting complete response (CR; > 40 months) and 1 partial response (PR). Of 9 evaluable patients on the continuous infusion regimen, there was 1 PR. Pharmacokinetic parameters for the bolus regimen at the MTD showed a mean maximum serum concentration (Cmax) of 1,209 +/- 430 ng/mL, with a median T1/2 beta for all courses of 18.2 hours (range, 10.0 to 80.0 hours), a volume of distribution (Vd) of 10.9 L (range, 3.1 to 34.5 L), and a clearance (CL) of 0.45 L/h (range, 0.13 to 2.3 L/h). For the CI regimen at MTD, the mean Cmax was 963 +/- 473 ng/mL, with a median T1/2 beta for all courses of 22.8 hours (range, 24.1 to 30.6 hours), a Vd of 9.4 L (range, 4.4 to 19.5 L), and a CL of 0.32 L/h (range, 0.12 to 0.55 L/h). Twenty-five percent of the patients on the bolus infusion regimen and 30% on the CI regimen made antibody against mouse Ig (HAMA) and/or ricin A chain antibody (HARA). We conclude that this IT can be administered safely and that both regimens achieve comparable peak serum concentrations at the MTD; these concentrations are similar to those achieved previously using other regimens with IgG-dgA ITs at their respective MTDs. Thus, toxicity is related to the serum level of the IT and does not differ with different targeting MoAbs.

CD40 and the effect of anti-CD40-binding on human multiple myeloma clonogenicity

CD40 is a 48 kDa glycosylated phospoprotein that is a member of the tumor necrosis factor receptor (TNF-R) superfamily. CD40 was originally identified in B lymphocytes, and is found on monocytes, dendritic cells, some carcinoma cell lines, and the thymic epithelium. CD40 is expressed on normal pre-B through mature B stages of differentiation. For normal B cells, the cross-linking of CD40 induces cell cycle progression, long-term proliferation in vitro, IgE secretion, increased adhesion molecule (LFA-1) expression, and low level IL-6 secretion. The natural ligand of CD40 (CD40L, gp39, or T-BAM, for T-B cell activating molecule) was recently identified as an inducible molecule expressed transitionally on activated T cells. Although originally believed to be absent in normal and malignant plasma cells, CD40 has been demonstrated on the majority of myeloma cell lines and myeloma cells from plasma cell dyscrasia (PCD) patient specimens tested. CD40 activation modulated myeloma cell proliferation and clonogenicity in vitro, suggesting that the CD40 pathway is active in myeloma cell growth. For the IL-6 dependent cell line ANBL-6, CD40 activation was associated with autocrine IL-6 production. However, the IL-6 pathway does not appear to play a predominant role in CD40 activation of non-IL-6-dependent MM cell lines and patient primary bone marrow cultures. The possible pathophysiologic role of the CD40 receptor in human multiple myeloma is discussed.

Chemosensitization of human hepatocellular carcinoma cells with cyclosporin A in post-liver transplant patient plasma

We previously showed that combined neoadjuvant doxorubicin (DOX) treatment and orthotopic liver transplantation produced a 3-year tumor-free survival rate of 54% in stage II-IVa nonresectable hepatocellular carcinomas (HCCs). These patients received posttransplant immunosuppressive doses of cyclosporin A (CsA). CsA has been shown to modify the function of a membrane P-glycoprotein (Pgp) whose overexpression is associated with a multidrug-resistant (MDR1) phenotype. This study utilized HCC cell lines to characterize the in vitro chemomodulatory properties of CsA as found in posttransplant patient plasma to consider the hypothesis that CsA may prolong posttransplant survival by enhancing the therapeutic efficacy of DOX against multidrug-resistant hepatoma cells. We characterized Pgp expression in the HCC lines Hep3B, Hep G2, and SK-HEP-1 by immunohistochemistry and the reverse transcription-polymerase chain reaction. The combined cytotoxicity of DOX + CsA was examined by [3H]thymidine uptake and flow cytometric drug-retention assays. Pgp expression was assessed further after prolonged (10-day) treatment with CsA. Hep3B and Hep G2 cells expressed low to moderate levels of Pgp. The effective DOX dose required for inhibiting MDR1(+) Hep3B and Hep G2 cell proliferation by 50% (DOX IC50) was 44.5 ng/ml and 43.5 microgram/ml, as compared with 10.7 ng/ml for Pgp-negative SK-HEP-1 cells. Optimal concentrations of CsA (0.8 micrometer) lowered DOX IC50 for Hep3B cells and Hep G2 cells by 6-fold and 4-fold, respectively. Similarly, plasma from patients containing immunosuppressive levels of CsA lowered DOX IC50 of the MDR1(+) Hep G2 cells by up to 4-fold. Prolonged exposure to CsA did not affect its chemosensitizing capacity or Pgp expression of HCC cells. PSC-833, a nonimmunosuppressive analogue of CsA, was equally effective in reducing the DOX IC50 of MDR1(+) HCC cells. CsA and PSC-833 increased drug retention by approximately 75%, but did not significantly affect hepatoma cell viability or Pgp expression. Pharmacological concentrations of cyclosporin analogues, including one nonimmunosuppressive form, enhance DOX cytotoxicity of MDR1(+) HCC cells by modulating drug retention. CsA as found in posttransplant patient plasma enhanced DOX cytotoxicity to human MDR1(+) hepatoma cells in vitro, albeit at less than optimal chemosensitizing concentrations. Prolonged exposure to CsA did not affect its chemosensitizing properties or block Pgp expression of HCC cells. These findings support our hypothesis that in vivo immunosuppressive levels of CsA may enhance DOX chemotherapeutic efficacy on MDR1(+) HCC cells.

Overexpression of myoglobin and assignment of its amide, C alpha and C beta resonances

Sperm whale apomyoglobin was expressed to high levels on minimal media and isotopically labeled with 13C and 15N nuclei. The isotopically labeled apoprotein was purified to homogeneity in a single step by reversed-phase chromatography and reconstituted with hemin and carbon monoxide gas for NMR analysis. Sequence-specific backbone 1HN, 15N and 13C alpha as well as side-chain 13C beta resonance assignments have been made for over 90% of the amino acids in the carbon monoxide complex of the protein. Resonance assignments were made by analysis of a series of 3D triple resonance spectra measured on the uniformly labeled sample. These assignments will provide the basis for analyzing the effects of point site mutations on the structure, stability and dynamics of the protein in solution.

Recombinant soluble human tissue factor secreted by Saccharomyces cerevisiae and refolded from Escherichia coli inclusion bodies: glycosylation of mutants, activity and physical characterization

Tissue factor (TF) is the cell-surface transmembrane receptor that initiates both the extrinsic and intrinsic blood coagulation cascades. The abilities of TF to associate with Factor VIIa and Factor X in a ternary complex and to enable proteolytic activation of Factor X by Factor VIIa reside in the extracellular domain of TF. We describe the expression of the surface domain of TF (truncated TF, tTF) in both Saccharomyces cerevisiae and Escherichia coli and the biochemical and physical characterization of the recombinant proteins. Wild-type tTF and several glycosylation-site mutants were secreted efficiently by S. cerevisiae under the control of the yeast prepro-alpha-signal sequence; the T13A,N137D double mutant was the most homogeneous variant expressed in milligram quantities. Wild-type tTF was expressed in a non-native state in E. coli inclusion bodies as a fusion protein with a poly(His) leader. The fusion protein could be fully renatured and the leader removed by proteolysis with thrombin; the correct molecular mass (24,729 Da) of the purified protein was confirmed by electrospray mass spectrometry. Recombinant tTFs from yeast, E. coli and Chinese hamster ovary cells were identical in their abilities to bind Factor VIIa, to enhance the catalytic activity of Factor VIIa and to enhance the proteolytic activation of Factor X by Factor VIIa. Furthermore, CD, fluorescence emission and NMR spectra of the yeast and E. coli proteins indicated that these proteins are essentially identical structurally.

The wisdom of Sir William Osler

William Osler (1849-1919) was generally regarded as the greatest and most respected physician of his time. He is still considered by many in these terms. Others have questioned the relevance of Osler's teachings in recent years. This paper describes Osler's life and gives his philosophy and views in his own words. An outstanding clinician who emphasized bedside teaching and observation, he possessed extraordinary charm that inspired many disciples. As Professor of Medicine at 4 institutions in 3 countries, he exerted a profound influence on medical education. He was a prolific writer and his textbook became the most popular and widely read treatise on medicine in the world. He also was a medical historian, a classical scholar, and an avid bibliophile. He emphasized the value of hard work and ongoing education. His comparison and concern for patients and colleagues reflected his personality. Osler's wisdom is as relevant now as in his era. It is likely that he would be in the forefront of medical science if he were alive today. Osler blended the art and science of medicine perhaps better than anyone else and remains a valuable role model for students and physicians more than 75 years after his death.

HLA compatibility and liver transplant outcome. Improved patient survival by HLA and cross-matching

In liver transplantation (LTx), numerous studies have failed to demonstrate an adverse effect of HLA-A,B,DR incompatibility or of donor-specific positive cross-match on survival of the recipients. In this study, we examined the effect of antidonor cytotoxic antibody and HLA compatibility in 800 LTx recipients with CsA-based immunosuppression. Thirty-four of 482 (7%) recipients were transplanted across a positive donor-specific T cell cross-match. Four-year patient and graft survival was 71% and 67%, respectively, in negative cross-match recipients and 53% and 50%, respectively, in positive cross-match recipients (P = 0.0051 and P = 0.023). Neither B cell-positive cross-match nor the presence of panel reactive antibody (PRA) had an adverse impact on the liver allograft outcome. Interestingly, 21/58 (36.2%) patients with PRA > or = 10% had a positive T cell cross-match, whereas only 7/382 (1.8%) patients with PRA < 10% did (P < 0.0001). This indicates the predictive value of PRA cross-match results. B lymphocyte cross-match results also were strongly correlated with the presence of PRA, as 26/57 (45.6%) of the patients with PRA > or = 10% had a positive cross-match, whereas only 22/394 (5.6%) with PRA < 10% did (P < 0.0001). Analysis of HLA compatibility demonstrated a significant impact on patient's survival, comparing only 0-2 vs. 6 HLA-A+B+DR mismatches and 0 vs. 1 vs. 2 HLA-DR mismatches. Four-year patient survival rate for 0 to 2 antigen mismatches was 86%, whereas for 6 antigen mismatches it was 62% (P = 0.025). Overall actuarial 4-year patient survival rate in HLA-DR-mismatched groups (0 vs. 1 vs. 2) was 84%, 73%, and 64%, respectively (P = 0.033). In no mismatched category was graft survival rate significantly different. Sepsis or rejection was the cause of graft loss in 1/10 (10%), 21/75 (28%), and 34/85 (40%) patients with 0, 1, and 2 HLA-DR mismatches, respectively. The difference between patient and graft survival was accounted for by survival after retransplantation, which was lower in patients with more HLA-DR mismatches in primary transplants. The latter group received intensive immunosuppressive therapy during the first month after primary transplantation, as compared with those with fewer HLA-DR mismatches (P = 0.04). The above data suggest that prospective cross-match should be performed in patients with > or = 10% PRA if it is logistically feasible.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-CD40 antibody binding modulates human multiple myeloma clonogenicity in vitro

Ligand binding of the B-cell lineage antigen CD40 enhances growth and interleukin-6 (IL-6) secretion in human B cells (the CD40/IL-6 loop). IL-6 has an autocrine and paracrine role in human multiple myeloma (MM) cell growth. With the use of the CD40 monoclonal antibody (MoAb) G28-5, we examined CD40 expression and the effect of CD40 binding on MM clonogenic colony (MCC) formation to characterize the IL-6/CD40 loop activity in MM. CD40 was expressed on plasmacytoid cells in 21 of 28 plasma cell dyscrasia (PCD) bone marrow (BM) biopsies tested (10 of 14 MM, 2 of 2 Waldenstrom's macroglobulinemia [WM], 2 of 2 plasma cell leukemia [PCL], 6 of 8 monoclonal gammopathy of undetermined significance [MGUS], and 1 of 2 primary amyloidosis [AL]). G28-5 binding increased MCCs by 35% to 150% in 11 of 17 CD40+ PCD BM cultures, but did not affect MCC formation in CD40- specimens or normal BM colony forming units (CFU-GEMM, CFU-GM, BFU-E). Responsive cultures originated from BM of patients with MM (2 of 5 cases tested), WM (2 of 2), PCL (2 of 2), and MGUS (5 of 6). CD40-responsiveness was not significantly inhibited by the presence of an anti-IL-6 MoAb (2 of 2 MGUS cultures tested), and did not correlate with the capacity to respond to IL-6 stimulation (n = 17, P > .05) or a detectable level of endogenous IL-6 (n = 15, P > .05). Additional studies were performed with PCD cell lines to characterize the interrelationship of CD40 activation and IL-6 production. Fifty percent to greater than 95% of cells from the RPMI 8226 and ARH77 lines expressed CD40, whereas 6% of U266 cells were CD40+. For RPMI 8226, ARH-77, and U266 cells, the increased MCC formation after anti-CD40 stimulation was not affected by the presence of an anti-IL-6 neutralizing MoAb and was not accompanied by detectable IL-6 secretion. There was no apparent increase in IL-6 mRNA transcription following G28-5 treatment of U266 or RPMI 8226 cells. Our observations indicate that CD40 is expressed in a subset of human myeloma cells present in various PCDs. Cell-line studies suggest that the CD40+ myeloma cell may regulate MM clonogenic colony formation without activating the IL-6 pathway.

Characterization of skin-infiltrating cells during acute graft-versus-host disease following bone marrow transplantation using unrelated marrow donors

To characterize skin-infiltrating T lymphocytes during acute GVHD, skin biopsies were obtained from two patients who received unrelated marrow matched for HLA-A, -B, -DR, and -DQ but mismatched for -DP. A total of 120 T-cell clones were generated. Phenotype analysis of the clones showed that the majority of cells were CD4+ and expressed alpha/beta TCR. HLA-DP oligonucleotide genotyping of the clones revealed the presence of lymphoid chimerism. PLT assay showed the lack of HLA specificity, including mismatched HLA-DP. However, mAb to HLA antigens blocked proliferation of the majority of the clones, indicating that the clones recognized HLA-associated molecules. Interestingly, proliferation of two CD4+ T-cell clones was inhibited by class I mAb. A few of the clones revealed augmented proliferation in the presence of CMV antigens and a few revealed cytolytic activity. The above study suggests that (a) CD4+ helper T cells may be primarily responsible for immunopathogenesis of skin manifestations during acute GVHD, (b) there is a mixed lymphoid chimerism in skin during acute GVHD, (c) HLA-DP may not be a factor contributing to the development of acute GVHD, (d) the peptide of the HLA groove or superantigen associated with HLA molecules may be the stimulatory antigen, and (e) CMV antigens appear to stimulate some of the skin-infiltrating T lymphocytes.

Mutational mapping of functional residues in tissue factor: identification of factor VII recognition determinants in both structural modules of the predicted cytokine receptor homology domain

Alanine scanning mutagenesis of tissue factor, the initiating receptor and cofactor molecule for the coagulation pathways, was used to define residue side chains with functional contributions. Approximately half of the residues were exchanged, and several stretches of functional residues throughout the entire extracellular domain were identified which contributed to overall coagulant function. Mutants were further characterized with respect to their affinity for binding of ligand, providing evidence that identified functional sequence spans are involved in ligand interaction. The tissue factor extracellular domain is suggested to adopt the folding pattern of the cytokine receptor homology unit, which is typically composed of two seven-beta-strand modules. Evaluation of the mutational analysis within this structural context suggests that functionally important residues are spatially proximate and clustered at the boundary of the predicted beta-strand modules. Residues contributing to ligand binding by tissue factor were identified in positions corresponding to ligand interactive residues in the growth hormone receptor and contact residues of other cytokine receptors, consistent with a conserved structural region for ligand interaction throughout the cytokine receptor family.

A phase I study of an anti-CD22-deglycosylated ricin A chain immunotoxin in the treatment of B-cell lymphomas resistant to conventional therapy

Twenty-six patients, whose B-cell lymphoma had relapsed after conventional therapies, were treated in a phase I dose escalation study with an immunotoxin consisting of a mouse CD22 monoclonal antibody (RFB4:IgG1K) coupled to chemically deglycosylated ricin A chain (dgA). Two to 12 doses of the immunotoxin were infused intravenously at 48-hour intervals. The peak serum concentration and half-life (T1/2) did not correlate directly with the dose and averaged 3.8 micrograms/mL and 7.8 hours, respectively. The main dose-limiting toxicity was caused by the vascular leak syndrome (VLS) consisting of weight gain, edema, serum albumin decrease, and critically by pulmonary edema. Myalgia occurred frequently and was only dose limiting in one patient who developed rhabdomyolysis. The presence of lymphoma cells in the blood (> or = 10(10)/L) and clinically detectable splenomegaly were associated with reduced toxicity and a shorter T1/2. Nine of 24 evaluable patients (37.5%) made antibody to either mouse Ig or dgA. There were five partial responses (PR) and one complete response (CR) lasting 30 to 78 days. High peak concentrations of immunotoxin in the serum, a long T1/2, and large areas under the curve (AUC) correlated with both clinical response and toxicity. None of three patients with CD5+ lymphomas (including two CLL patients) had more than mild toxicity or responded to the immunotoxin.

Heterotransplantation of human multiple myeloma cell lines in severe combined immunodeficiency (SCID) mice

Human multiple myeloma (MM) xenografts have been difficult to establish in athymic mice. We examined the feasibility of establishing human MM xenograft growth in SCID mice following subcutaneous (sc) injection of 1-2 x 10(7) cells from the human plasma cell dyscrasia (PCD) cell lines RPMI 8226 and ARH-77. SC tumors emerged in 67% (6/9) of RPMI 8226- and 6 of 6 ARH-77-injected mice after a latency period of 9-54 days, and reached 19-35 mm in diameter before the mice were sacrificed. RPMI 8226 and ARH-77 primary tumor DNA hybridized positively with the human genome probe Alul-(Blur8), confirming successful engraftment of the human MM cell lines. The RPMI 8226 xenografts comprised predominantly of plasmacytoid cells that expressed the relevant cytoplasmic immunoglobulin (cIg) light chain isotype. Xenografted RPMI 8226 cells also expressed CD10 (CALLA; 44% reactive cells), CD38 (OKTIO; 69%), CD5 (49%), and reacted with the MM monoclonal antibody MM4 (39%). Human MM growth appeared to be localized subcutaneously for both RPMI 8226 and ARH-77 xenografts. There were no detectable metastatic foci in kidney, brain, heart, or bone marrow. Whereas diffuse plasma cell infiltrates were observed in spleen, GI tract, and lung biopsies of tumor-bearing mice, these infiltrates were of host origin according to immunophenotyping and DNA analyses. Neither the originating RPMI 8226 line nor its SCID mouse xenograft expressed Epstein Barr virus (EBV) genome sequences. These observations indicate that both EBV- (RPMI 8226) and EBV+ (ARH-77) cell lines can be successfully propagated in SCID mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular basis for methoxyamine-initiated mutagenesis: 1H nuclear magnetic resonance studies of oligonucleotide duplexes containing base-modified cytosine residues

Methoxyamine, N4-methoxycytidine and its 2'-deoxyribo analogue are transition mutagens. The mechanism by which the latter acts after incorporation into or generation within DNA has been ascribed to the ability of the base analogue to pair effectively with both adenine and guanine. To obtain a detailed understanding of these interactions, the solution structures of the self-complementary octanucleotide d(CGGATCCG) and its analogues d(CGGATTCG), d(CGGATMCG) and d(CGGATPCG) (designated 8mer-GC, -GT, -GM and -GP, respectively) were investigated by 1H nuclear magnetic resonance spectroscopy; M is N4-methoxycytosine (mo4C) and P is an analogue, the bicyclic dihydropyrimido[4,5-c][1,2] oxazin-7-one. A variable temperature study showed the order of stability as 8mer GC > GP > GT > GM. Nuclear Overhauser spectroscopy permitted the assignment of the base, anomeric and H2'/H2" protons in these 8mers. All had spectra consistent with regular B-DNA duplex structures. Imino proton spectra showed that the 8mers GC, GP and GM involved Watson-Crick base-pairing but that the G.P and to a greater extent G.M base-pairs were in slow exchange on the nuclear magnetic resonance time-scale with the wobble configuration. Indeed, the G.M pair showed an additional exchange process interpreted in terms of the presence of syn and anti conformers of the methoxy group in the wobble pair. This accounts for the destabilization of M compared with the P-containing duplex. The observations are compared with those made earlier on the corresponding AT, AP and AM octamers. It is evident that M and P can form stable base-pairs with both A and G with essentially Watson-Crick geometry. This confirms the earlier, although unsubstantiated explanation for the transition mutational propenstty of methoxyamine which, in turn, was based on the fact that methoxycytosine bases have tautomeric constants (KT) much nearer to unity than the normal bases. The same general explanation for hydroxylamine and hydrazine-induced mutations is correspondingly rendered more certain.