Chest pain mimicking pulmonary embolism may be a common presentation of COVID-19 in ambulant patients without other typical features of infection.

BACKGROUND: Radiological and pathological studies in severe COVID-19 pneumonia (SARS-CoV-2) have demonstrated extensive pulmonary immunovascular thrombosis and infarction. This study investigated whether these focal changes may present with chest pain mimicking pulmonary emoblism (PE) in ambulant patients. METHODS: CTPAs from outpatients presenting with chest pain to Leeds Teaching Hospital NHS Trust 1st March to 31 May 2020 (n = 146) and 2019 (n = 85) were compared. Regions of focal ground glass opacity (GGO), consolidation and/or atelectasis (parenchymal changes) were determined, and all scans were scored using British Society for Thoracic Imaging (BSTI) criteria for COVID-19, and the 2020 cohort was offered SARS-CoV-2 antibody testing. RESULTS: Baseline demographic and clinical data were similar between groups with absence of fever, normal lymphocytes and marginally elevated CRP and D-Dimer values. Evidence of COVID-19 or parenchymal changes was observed in 32.9% (48/146) of cases in 2020 compared to 16.5% (14/85) in 2019 (P = 0.007). 11/146 (7.5%) patients met BSTI criteria for COVID-19 in 2020 compared with 0/14 in 2019 (P = 0.008). 3/39 patients tested had detectable COVID-19 antibodies (2 with parenchymal changes and 1 with normal parenchyma) however 0/6 patients whose CTPA met BSTI criteria "likely/suspicious for COVID-19" and attended antibody testing were SARS-CoV-2 antibody positive. CONCLUSIONS: 32.8% ambulatory patients with suspected PE in 2020 had parenchymal changes with 7.5% diagnosed as COVID-19 infection by imaging criteria, despite the absence of other COVID-19 symptoms. These findings suggest that localized COVID-19 pneumonitis with immunothrombosis occurs distal to the bronchiolar arteriolar circulation, causing pleural irritation and chest pain without viraemia, accounting for the lack of fever and systemic symptoms.

Bacterial diversity associated with ornithogenic soil of the Ross Sea region, Antarctica.

In the Ross Sea region of Antarctica, ornithogenic soils form on land under Adélie Penguin rookeries. Compared with mineral soils of the Ross Sea region, ornithogenic soils are generally high in microbial biomass, organic carbon, and total nitrogen and phosphorus, with high electrical conductivity and large variations in pH. The objective of this study was to assess the bacterial composition of ornithogenic soils from Cape Hallett and Cape Bird in the Ross Sea region using culture-independent methods. Soil clone libraries were constructed and those clones that occurred > or = 3 times were sequenced. The bacterial diversity of the soils was dependent on the presence of penguins. Firmicutes most closely related to the endospore-formers (e.g., Oceanobacillus profundus and Clostridium acidurici) and (or) Gammaproteobacteria belonging to the genus Psychrobacter dominated soils currently occupied with penguins. In contrast, Gammaproteobacteria, closely related to cultured members of the genera Rhodanobacter, Psychrobacter, Dokdonella, and Lysobacter, dominated the soils previously colonized by penguins. Results of this study indicate that despite relatively high nutrient levels and microbial biomass, bacterial communities of ornithogenic soils were not more diverse than those of mineral soils of the Ross Sea region of Antarctica.

Mobilized blood cells vs bone marrow harvest: experience compared in 171 donors with particular reference to pain and fatigue.

This prospective study compared the donor experience of blood cell (BC) mobilization and leukapheresis (n=116) with that of bone marrow (BM) harvest (n=55). Internal jugular catheters were inserted electively in 89% of BC donors. Most (80%) BM donors had a harvest with general anesthesia; 20% had epidural or spinal anesthesia. Pain and fatigue were frequent with both procedures and were compared in responses to questionnaires. A total of 85% of BM donors reported moderate or severe pain compared with 68% of BC donors (P=0.02). The median duration of pain was 14 days for BM donors compared with 3 days after BC mobilization (P<0.0001). More BM donors had pain for more than 7 days (75% vs 0%, P<0.0001). Severe fatigue was experienced by more BM donors (49 vs 16%, P<0.0001). Fatigue lasted significantly longer in BM donors (median 11 vs 4 days, P<0.0001) and more BM donors were fatigued for more than 1 week (69 vs 0%, P<0.0001). A total of 11 donors had both BM and BC collection; seven preferred the latter. Simply considered with respect to pain and fatigue, BC donation appears better tolerated by donors. However, there are other sequelae of both influencing the acceptability for individual donors.

Micrometastases in apheresis products predict shorter progression-free and overall survival in patients with breast cancer undergoing high-dose chemotherapy (HDCT) and autologous blood stem cell transplantation (ABSCT).

The presence of cancer cells in autografts of breast cancer patients has been described to have prognostic value or directly lead to relapse. Previously, we demonstrated that apheresis products (APs) collected after induction chemotherapy have a significantly lower likelihood of tumor cell contamination. Here, we examine the prognostic value of micrometastases in autografts. Data from 83 patients with breast cancer treated with autologous blood stem cell transplantation were analyzed. Pan-cytokeratin-FITC conjugated antibodies were used to detect contaminating breast cancer cells in the APs. Progression and survival data analyzed on the basis of three or fewer cancer cells showed no significant differences in outcomes. Of the 83 patients, 11 had more than three cancer cells detectable in their APs. In total, 72 patients were shown to have less than three cells detectable. When patients with more than three cells were compared to patients with 0-3, we found statistically significant differences in progression-free survival. We also found a significant difference in overall survival (OS) between the two groups. No difference was observed in OS since the time of diagnosis. We conclude that patients with more than three contaminating cells in their APs have micrometastases and represent a poor prognosis group.

Thermal decomposition of a gaseous multiprotein complex studied by blackbody infrared radiative dissociation. Investigating the origin of the asymmetric dissociation behavior.

The blackbody infrared radiative dissociation technique was used to study the thermal decomposition of the gaseous B5 pentamer of the Shiga-like toxin I and its complexes with the Pk trisaccharide and a decavalent Pk-based oligosaccharide ligand (STARFISH, S). Dissociation of the protonated pentamer, (B5 + nH)n+ triple bond B5n+ where n = 11-14, proceeds almost exclusively by the loss of a single subunit (B) with a disproportionately large fraction (30-50%) of the parent ion charge. The degree of charge enrichment of the leaving subunit increases with increasing parent ion charge state. For n = 12-14, a distribution of product ion charge states is observed. The yields of the complementary pairs of product ions are sensitive to the reaction temperature, with higher temperatures favoring greater charge enrichment of the leaving subunit for +13 and +14, and the opposite effect for +12. These results indicate that some of the protons are rapidly exchanged between subunits in the gas phase. Dissociation of B5(14+) x S proceeds exclusively by the loss of one subunit, although the ligand increases the stability of the complex and also reduces the degree of charge enrichment in the ejected monomer. For B5(12+)(Pk)1-3, the loss of neutral Pk competes with loss of a subunit at low temperatures. Linear Arrhenius plots were obtained from the temperature-dependent dissociation rate constants measured for the loss of B from B5n+ and B514+ x S. The magnitude of the Arrhenius parameters is highly dependent on the charge state of the pentamer: Ea = 35 kcal/mol and A = 1,019 s(-1) (+14), 46 kcal/mol and 1,023 S(-1) (+13), 50 kcal/mol and 1026 s(-1) (+12), and 80 kcal/mol and 10(39) (+11). The Ea and A for B5(14+) x S are 59 kcal/mol and 10(30) s(-1), respectively. The reaction pathways leading to greater charge enrichment of the subunit lost from the B5(14+) and B5(13+) ions correspond to higher energy processes, however, these pathways are kinetically preferred at higher temperatures due to their large A factors. A simple electrostatic model, whereby charge enrichment leads to Coulombic repulsion-induced denaturation of the subunits and disruption of the intersubunit interactions, provides an explanation for the magnitude of the Arrhenius parameters and the origin of the asymmetric dissociation behavior of the complexes.

Late renal transplant failure: an adverse prognostic factor at initiation of peritoneal dialysis.

BACKGROUND: Early renal transplant failure necessitating a return to dialysis has been shown to be a poor prognostic factor for survival. Little is known about the outcome of patients with late transplant failure returning to dialysis. It was our clinical impression that late transplant failure (>2 months) carries an increased morbidity and mortality risk in patients returning to dialysis. OBJECTIVE: To determine whether patients with a failed renal transplant have an outcome different to those on dialysis who have never received a kidney transplant. SETTING: Peritoneal dialysis (PD) unit in a teaching hospital. PATIENTS AND DESIGN: All failed renal transplant patients (fTx) in the Toronto Hospital Peritoneal Dialysis program between 1989 and 1996 were identified. This cohort of 42 fTx patients was compared with a cohort of randomly selected never-transplanted PD patients (non-Tx). The PD program was selected because of the availability of well-documented patient archival material. The non-Tx group was matched for age and presence of diabetes. Data were collected until retransplantation, change of dialysis modality or center, death, or until June 1998. RESULTS: There was no difference at initiation of PD between groups in serum albumin, residual renal function, or mean serum parathyroid hormone level. The mean low-density lipoprotein level was significantly higher in the fTx cohort. The duration of dialysis before Tx in fTx patients accounted for the increased total length of dialysis in fTx (mean 15 months). However, post-Tx the duration of PD was similar for both groups (30.7 months for fTx vs 31.6 months for non-Tx). The fTx group had a considerably worse outcome than the non-Tx group. The time to first peritonitis, subsequent episodes of peritonitis, catheter change, or transfer to hemodialysis occurred at a much faster rate in fTx patients. The most dramatic difference was in survival. There were 3 deaths in the non-Tx group and 12 in the fTx group (p < 0.01). The mean age at time of death in the fTx group was 47.5 years. Deaths were due mainly to gram-negative peritonitis and cardiovascular disease. CONCLUSIONS: We conclude that late failed renal transplant patients starting dialysis are at increased risk of complications and have strikingly higher mortality rates than non-Tx patients. A previously failed kidney transplant can be considered an adverse prognostic factor for patients commencing PD; these patients need to be closely monitored. Although this study was limited to PD patients, the same principles likely apply to fTx patients returning to any form of renal replacement therapy.

The CD3- 16+ 56+ NK cell count independently predicts autologous blood stem cell mobilization.

Better predictive factors for autologous blood stem cell mobilization (BSCM) are needed. The purpose of this study was to determine if an independent association exists between lymphocyte or NK cell counts and BSCM. Data were analyzed on 141 consecutive patients aged 19-69 years (median 45) who received combined chemotherapy plus G-CSF for BSCM, and who had measurements of immune cells prior to BSCM. Of the 141 patients, 41% had breast cancer, 14% Hodgkin's disease, 34% non-Hodgkin's lymphoma, and 11% other diagnoses. BSCM involved dose-intensive cyclophosphamide, etoposide, cisplatin (DICEP) plus G-CSF 300 microg (<70 kg) or 480 microg (>70 kg) for 45% of patients, while the remaining 55% received other chemotherapy plus similar doses of G-CSF. Only a single apheresis was performed for 94% of patients. The following factors were analyzed for predictors of BSCM: age, gender, prior chemotherapy, prior radiotherapy, diagnosis, disease status, marrow involvement, mobilization regimen, Hb, WBC, platelet count, B cell, T cell, and NK cell counts. The peripheral blood CD34+ counts on the first day of apheresis (PBCD34) were 6-1783 x 10(6)/l (median 150). The PBCD34 count correlated strongly with the number of CD34+ cells collected/l blood apheresed and with the number of CD34+ cells collected/kg. By multivariate analysis using continuous variables, relapsed status (P = 0.0003), not using DICEP mobilization (P = 0.0001), female gender (P = 0.0057), low platelet count (P = 0.051), and low CD3- 16+ 56+ count (P = 0.0158) were associated with low PBCD34 counts. Using categorical variables, the only factors that independently predicted a PBCD34 count <150 x 10(6)/l were: >1 prior chemotherapy regimen (odds ratio = 5.12, P = 0.0003), not using DICEP mobilization (odds ratio = 4.94, P = 0.0001), and CD3- 16+ 56+ count <125 x 10(6)/l (odds ratio= 2.58, P = 0.0157). In conclusion, the CD3- 16+ 56+ count may be a useful additional predictor of BSCM and warrants further study.

The observation of multivalent complexes of Shiga-like toxin with globotriaoside and the determination of their stoichiometry by nanoelectrospray Fourier-transform ion cyclotron resonance mass spectrometry.

We show by nanoelectrospray ionization (nanoES) Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) that it is possible to observe oligosaccharide-protein complexes with dissociation constants in the millimolar range, such as P(k) trisaccharide (globotriaoside) complexed with the Shiga-like toxin (SLT) of pathogenic E. coli. It is further demonstrated that nanoES/FT-ICR MS is an exquisite method to study quantitative aspects of the association of mono- and polyvalent oligosaccharide ligands with multimeric proteins, such as the SLTs. At increasing trisaccharide:protein ratios it was shown that the B(5 )toxin subunit complexes with 5 P(k) trisaccharides and only after all 5 copies of site 2 are essentially filled do any of the remaining 10 receptor sites become occupied. From the distribution of bound P(k)'s at the five binding sites, it was possible to establish association constants for each of the five sites and to confirm that binding occurs noncooperatively, the association constants for each site are identical and that compared to site 1, site 2 exhibits a tenfold higher affinity for the globotriaoside synthetic ligand 1. The facile identification of the occupancy of binding sites represents information that is not readily available by other techniques. This sensitive and rapid estimation of association constants for protein-ligand complexes, which are free of unpredictable secondary effects that plague enzyme linked assays, is likely to find wide application.

A Low CD34+ Cell Dose Predicts Relapse and Death Early following Autologous Blood Stem Cell Transplantation.

The purpose of this study was to determine if the CD34+ cell dose is independently associated with progression-free (PFS) and overall survival (OAS) for patients treated with autologous blood stem cell transplantation (ASCT). From 1993 to 1999, 277 consecutive patients received ASCT in Calgary for stage 2/3 breast cancer (n = 65), metastatic breast cancer (n = 33), aggressive non-Hodgkin's lymphoma (NHL n = 80), low grade NHL (n = 21), Hodgkin's disease (n = 31), or other cancers (n = 47). Disease status at ASCT was first remission (n = 123), relapse (n = 112), or refractory (n = 42). Patients were grouped into quartiles according to the CD34+ cell dose (<4, 4-7, 7-14, and > 14 × 10(6)/kg). Univariate and multivariate analyses were performed for both PFS and OAS considering the following factors: age, gender, diagnosis, disease status (first remission, relapse, refractory), number of prior chemotherapy regimens, prior radiotherapy (RT), mobilization regimen (G-CSF only, Chemotherapy plus G-CSF, or dose-intensive cyclophosphamide, etoposide, cisplatin (DICEP) plus G-CSF), TBI or non-TBI conditioning, and CD34+ cell dose. The most discriminating cut point of the CD34+ dose for PFS (p <.0001, r(2) =.064) and OAS (p <.0001, r(2) =.066) was found to be 4 × 10(6)/kg. There was no difference in PFS or OAS between the three quartiles above 4 × 10(6)/kg. Using Cox proportional hazards models, factors independently associated with PFS were CD34+ dose < 4 × 10(6)/kg (RR = 2.21, p <.0001), refractory disease status (RR= 6.03, p <.0001), relapsed disease status (RR = 2.04, p =.002), and age > 50 years (RR = 1.91, p =.002). Factors independently associated with OAS were CD34+ dose < 4 × 10(6)/kg (RR = 2.14, p =.0007), refractory disease status (RR = 5.35, p <.0001), relapsed disease status (RR = 2.23, p =.0033), and age > 50 years (RR = 1.81, p =.012). In conclusion, a CD34+ cell dose less than 4 × 10(6)/kg independently predicted lower PFS and OAS rates following ASCT.

Double high-dose therapy for Hodgkin's disease with dose-intensive cyclophosphamide, etoposide, and cisplatin (DICEP) prior to high-dose melphalan and autologous stem cell transplantation.

We previously reported a 50% (95% CI = 33-76%) 5 year event-free survival (EFS) rate for 23 patients with Hodgkin's disease (HD) who received salvage therapy with single agent high-dose melphalan (HDM) and autologous stem cell transplantation (ASCT). Predictors of poor outcome included bulky disease and initial remission <1 year. Since 1995, similar poor prognosis patients have been treated with double high-dose therapy consisting of dose-intensive cyclophosphamide 5.25 g/m2, etoposide 1.05 g/m2, cisplatin 105 mg/m2 (DICEP) for tumor cytoreduction and stem cell mobilization followed by HDM/ASCT. The purpose of the present study is to determine if the use of DICEP is associated with improved event-free (EFS) and overall survival (OAS) for patients treated with HDM/ASCT. From February 1981 to June 1999, 46 consecutive patients received HDM/ASCT for relapsed (n = 35) or refractory (n = 11) HD. DICEP re-induction and blood stem cell mobilization was used for 21 patients. Factors considered for univariate and multivariate analyses included age at transplant, number of failed chemotherapy regimens, prior radiotherapy, length of initial remission, relapsed or refractory disease status, extranodal relapse, B symptoms at relapse, bulk, post-ASCT radiotherapy, and DICEP re-induction therapy. Cox proportional hazards models were constructed for both event and death. DICEP and HDM were well tolerated with no early treatment-related mortality or toxicity requiring life-sustaining measures. For all 46 patients, the projected 5 year EFS was 52% (95% CI = 38-72%) and OAS was 57% (95% CI = 40-82). Factors independently associated with relapse in multivariate analysis included bulk >5 cm (RR = 6.38, P = 0.002), prior radiotherapy (RR = 3.59, P = 0.027), and not using DICEP (RR = 5.29, P = 0.005). Factors independently associated with death included bulk >5 cm (RR = 5.13, P = 0.009), > or =3 prior chemotherapy regimens (RR = 4.72, P = 0.019), and not using DICEP (RR = 7.49, P = 0.015). This study demonstrates that DICEP re-induction prior to HDM/ASCT is feasible. The preliminary data are sufficiently encouraging to warrant a multicenter phase II or a phase III trial evaluating DICEP followed by HDM/ASCT as salvage therapy for HD.

Image-guided central venous catheter placement for apheresis in allogeneic stem cell donors.

Peripheral blood stem cell harvest by apheresis is an increasingly important procedure utilized in the treatment of many malignancies. Whether autologous or allogeneic, it is frequently performed via peripheral access because of concern over major complications associated with central venous catheter placement. This study was to determine the safety and success, complications and premature failure rates for radiolocally placed ultrasound-guided non-tunneled central venous catheters placed for apheresis in a donor (allogeneic) population. One hundred central venous catheters were placed in ninety-one individuals for allogeneic stem cell harvest. Procedural success and complications relating to placement were noted in all. In 97 cases the number of needle passes required for venous cannulation and whether this was achieved with a single wall puncture was noted. Duration of catheterization and reason for removal were recorded in all cases. All catheters were placed by a right transjugular route. Venous cannulation and functioning line placement was achieved in every case; 92/97 (95%) required only a single needle pass and 84/97 (87%) only a single wall puncture. There were no placement related complications; 94 catheters were removed the same day with the remainder removed within 48 hr. All completed apheresis. Our study demonstrates the safe use of central venous catheters for apheresis in normal donors if ultrasound guidance is used for the puncture and the duration of catheterization is short.

Quality assurance of progenitor cell content of apheresis products: a comparison of clonogenic assays and CD34+ enumeration. The Canadian Apheresis Group and Canadian Bone Marrow.

The most common methods used for evaluation of the haematopoietic stem cell content of peripheral blood apheresis products are the colony forming cell assay and the enumeration of CD34+ cells by flow cytometry. The Canadian Apheresis Group and the Canadian Bone Marrow Transplant Group established a multicentre study to compare the reproducibility of colony forming cell assays and CD34+ enumeration by flow cytometry in six transplant centres routinely performing haematopoietic stem cell apheresis. Over a 5-month period in 1996, 31 fresh apheresis samples were shipped by overnight courier for testing at six centres to perform CD34+ enumeration by flow cytometry and clonogenic assays. The mean coefficient of variation and range for the following assays were: cell count 36% (2.6-148%), CFU-GM 82% (46-123%), CD34+ absolute/kg 60% (14-174%) and CD34+ per cent 42% (12-84%). The wide variation in cell count in this pilot study highlights the difficulties related to provision of samples for quality assessment programmes. Results showed poor interinstitutional reproducibility even among selected samples with similar cell counts for both CFC and CD34+ assays demonstrating the need for development and implementation of an interinstitutional quality assurance programme for haematopoietic stem cell assessment. Provision of a reliable source of testing material will be a necessary next step.

The CD34+90+ cell dose does not predict early engraftment of autologous blood stem cells as well as the total CD34+ cell dose.

CD90 or Thy-1 is an antigen co-expressed with CD34+ on putative immature hematopoietic stem cells. Peak mobilization of CD34+90+ cells into the blood occurs a few days earlier than peak mobilization of total CD34+ cells. Because it is not known which cell type best correlates with engraftment, the optimal timing of apheresis remains unclear. The purpose of the study was to determine if the CD34+90+ cell dose predicts engraftment of autologous blood stem cells independent of the total CD34+ cell dose/kg, the dose of other CD34+ cell subsets (CD34+33-, CD34+38-, CD34+41+), or various clinical factors. Data were analyzed on 125 consecutive patients ranging in age from 19 to 66 years (median 46) who underwent autologous blood stem cell transplantation (ABSCT) for breast cancer (54), lymphoma (59), or other malignancies (12). By univariate analysis, neutrophil (> or = 0.5 x 10(9)/l) and platelet (> or = 20 x 10(9)/l or > or = 100 x 10(9)/l) engraftment correlated better with the total CD34+ cell dose than with the CD34+90+ cell subset. Using Cox proportional hazards models, factors independently associated with both neutrophil engraftment (> or = 0.5 x 10(9)/l) and platelet engraftment (> or = 20 x 10(9)/l and > or = 100 x 10(9)/l) were higher total CD34+ dose/kg and high-dose regimen (melphalan-containing slower than other regimens). In conclusion, the total CD34+ dose/kg was a better predictor of hematopoietic engraftment following ABSCT than the dose of any CD34+ subset, including CD34+90+ cells. Apheresis should continue to be timed according to peak CD34+ levels.

Predictive factors for long-term engraftment of autologous blood stem cells.

Data from 170 consecutive patients aged 19-66 years (median age 46 years) who underwent unmanipulated autologous blood stem cell transplant (ASCT) were analyzed to determine if total CD34+ cells/kg infused, CD34+ subsets (CD34+41+, CD34+90+, CD34+33-, CD34+38-, CD34+38-DR-), peripheral blood CD34+ cell (PBCD34+) count on first apheresis day, or various clinical factors were associated with low blood counts 6 months post ASCT. Thirty-four patients were excluded from analysis either because of death (n = 17) or re-induction chemotherapy prior to 6 months post ASCT (n = 13), or because of lack of follow-up data (n = 4). Of the remaining 136 patients, 46% had low WBC ( < 4 x 10(9)/l), 41% low platelets (<150 x 10(9)/l), and 34% low hemoglobin ( < 120 g/l) at a median of 6 months following ASCT. By Spearman's rank correlation, both the total CD34+ cell dose/kg and the PBCD34+ count correlated with 6 month blood counts better than any subset of CD34+ cells or any clinical factor. The PBCD34+ count was overall a stronger predictor of 6 month blood counts than was the total CD34+ cells/kg infused. Both factors retained their significance in multivariate analysis, controlling for clinical factors. In conclusion, subsets of CD34+ cells and clinical factors are inferior to the total CD34+ cell dose/kg and PBCD34+ count in predicting 6 month blood counts following ASCT.

Dissociation energies of deoxyribose nucleotide dimer anions measured using blackbody infrared radiative dissociation.

The dissociation kinetics of deprotonated deoxyribose nucleotide dimers were measured using blackbody infrared radiative dissociation. Experiments were performed with noncovalently bound dimers of phosphate, adenosine (dAMP), cytosine (dCMP), guanosine (dGMP), thymidine (dTMP), and the mixed dimers dAMP.dTMP and dGMP.dCMP. The nucleotide dimers fragment through two parallel pathways, resulting in formation of the individual nucleotide or nucleotide + HPO3 ion. Master equation modeling of this kinetic data was used to determine threshold dissociation energies. The dissociation energy of (dGMP.dCMP-H)- is much higher than that for the other nucleotide dimers. This indicates that there is a strong interaction between the nucleobases in this dimer, consistent with the existence of Watson-Crick hydrogen bonding between the base pairs. Molecular mechanics simulations indicate that Watson-Crick hydrogen bonding occurs in the lowest energy structures of (dGMP.dCMP-H)-, but not in (dAMP.dTMP-H)-. The trend in gas phase dissociation energies is similar to the trend in binding energies measured in nonaqueous solutions within experimental error. Finally, the acidity ordering of the nucleotides is determined to be dTMP < dGMP < dCMP < dAMP, where dAMP has the highest acidity (largest delta Gacid).

Hydration of gas-phase ions formed by electrospray ionization.

The hydration of gas-phase ions produced by electrospray ionization was investigated. Evidence that the hydrated ions are formed by two mechanisms is presented. First, solvent condensation during the expansion inside the electrospray source clearly occurs. Second, some solvent evaporation from more extensively solvated ions or droplets is apparent. To the extent that these highly solvated ions have solution-phase structures, then the final isolated gas-phase structure of the ion will be determined by the solvent evaporation process. This process was investigated for hydrated gramicidin S in a Fourier-transform mass spectrometer. Unimolecular dissociation rate constants of isolated gramicidin S ions with between 2 and 14 associated water molecules were measured. These rate constants increased from 16 to 230 s-1 with increasing hydration, with smaller values corresponding to magic numbers.

Factors predicting engraftment of autologous blood stem cells: CD34+ subsets inferior to the total CD34+ cell dose.

Data were analyzed on 178 consecutive patients (median age 43 years) who underwent autologous blood stem cell transplantation (ABSCT) at a single institution to determine if CD34+ subsets (CD34+38-, CD34+33-, CD34+33+, CD34+41+) or various clinical factors affect hematopoietic engraftment independent of the total CD34+ cell dose/kg. Using Cox proportional hazards models, the factors independently associated with rapid neutrophil engraftment were higher CD34+ dose/kg, use of G-CSF post-ABSCT, and conditioning regimen (single-agent melphalan +/- TBI slower). Factors independently associated with rapid platelet engraftment were higher CD34+ cell dose/kg, higher ratio of CD34+33-/total CD34+ cells infused, conditioning regimen (mitoxantrone, vinblastine, cyclophosphamide faster), and no CD34+ cell selection of the autograft. The CD34+ cell selection process seemed to deplete CD34+41+ cells to a greater extent than total CD34+ cells which may explain our observation that it resulted in slower platelet engraftment. In conclusion, the total CD34+ dose/kg was a better predictor of hematopoietic engraftment following ABSCT than the dose of any CD34+ subset. Platelet engraftment, however, was also influenced by the ratio of CD34+33-/total CD34+ cells for unmanipulated autografts, and possibly by the CD34+41+ dose for autografts manipulated by CD34+ selection. The use of CD34+ subsets requires further investigation in predicting engraftment of autografts which undergo ex vivo manipulation.

Superior autologous blood stem cell mobilization from dose-intensive cyclophosphamide, etoposide, cisplatin plus G-CSF than from less intensive chemotherapy regimens.

The study purpose was to determine if G-CSF plus dose-intensive cyclophosphamide 5.25 g/m2, etoposide 1.05 g/m2 and cisplatin 105 mg/m2 (DICEP) results in superior autologous blood stem cell mobilization (BSCM) than less intensive chemotherapy. From January 1993 until May 1997, 152 consecutive patients with non-Hodgkin's lymphoma (n = 55), breast cancer (n = 47), Hodgkin's disease (n = 14), multiple myeloma (n = 9), AML (n = 9), or other cancers (n = 18) initially underwent BSCM by one of three methods: Group 1: G-CSF alone x 4 days (n = 30). Group 2: disease-oriented chemotherapy, dosed to avoid blood transfusions, followed by G-CSF starting day 7 or 8, and apheresis day 13 or 14 (n = 82). Group 3: DICEP days 1-3, G-CSF starting day 14, and apheresis planned day 19, 20 or 21 (n = 40). A multivariate analysis was performed to determine which factors independently predicted BSCM. The median peripheral blood CD34+ (PB CD34+) cell count the morning of apheresis linearly correlated with the number of CD34+ cells removed per litre of apheresis that day. The median PB CD34+ cell count and median CD34+ cells x 10(6) removed per litre of apheresis were highest for Group 3, intermediate for Group 2, and lowest for Group 1. By multivariate analysis, mobilization group (3 > 2 > 1), disease other than AML, no prior melphalan or mitomycin-C, and less than two prior chemotherapy regimens predicted better BSCM. Out of 15 Group 3 patients who had infiltrated marrows, 11 had no detectable cancer in marrow and apheresis products after DICEP. These data suggest that DICEP results in superior BSCM than less intensive chemotherapy regimens.

Image-guided central venous catheters for apheresis.

Apheresis is an increasingly important procedure in the treatment of a variety of conditions, sometimes performed via peripheral access because of concern over major complications associated with central venous catheter (CVC) placement. This study sought to determine the safety and success for ultrasound and fluoroscopically guided, non-tunneled dual lumen CVCs placed for apheresis. Prospective data collection was made of 200 attempted CVC placements in the radiology department utilizing real time sonographic guidance. The complications relating to placement were noted in all and the number of passes required for venepuncture and whether a single wall puncture was achieved was recorded in 185 cases. Duration of catheterization and reason for line removal were recorded in all. Our study group included 71 donors providing peripheral blood stem cells for allogeneic transplant. CVCs were successfully placed in all patients, 191 lines in the internal jugular and seven in the femoral vein. 86.5% required only a single pass and 80.5% with only anterior wall puncture. Inadvertent but clinically insignificant arterial puncture occurred in six (3%) cases. In no case did this prevent line placement. There were no other procedure-related complications. 173 (87.4%) catheters were removed the same day. No catheters were removed prematurely. There was one case of prolonged venous bleeding. Our study demonstrates the safety of central venous catheters for apheresis provided that duration of catheterization is short and real-time sonographic guidance is used for the puncture, and guide wire and catheter placement are confirmed fluoroscopically.