Sustained Homocysteine-Lowering Effect over Time of Folic Acid-Based Multivitamin Therapy in Stroke Patients despite Increasing Folate Status in the Population

BACKGROUND AND AIMS

It is uncertain what impact increasing voluntary folate fortification may be having on the statistical power of randomized trials testing the homocysteine hypothesis of atherothrombosis. The objective of this study was to determine whether there has been a change in folate status between 1998 and 2002 in stroke patients randomized into the VITAmins TO Prevent Stroke (VITATOPS) Study at a single center in Perth, Australia, and what impact this may have had on the magnitude of the homocysteine-lowering effect achieved over time with folic acid-based multivitamin therapy.

METHODS

We conducted a randomized, double-blind, placebo-controlled study involving 285 patients with stroke or transient ischemic attack who were recruited between 1998 and 2002 and randomized to long-term folic acid 2.0 mg/day, pyridoxine 25 mg/day and cobalamin 0.5 mg/day (active VITATOPS medication) or placebo. Fasting plasma total homocysteine, red cell folate, serum cobalamin and serum pyridoxine levels were measured at baseline and 6 months, and the change in blood levels over 4 time quartiles and differences in levels between the two randomized treatments were examined.

RESULTS

Between 1998 and 2002, there was a significant rise in baseline mean red cell folate levels over 4 time quartiles among the entire stroke cohort (723.3, 780.1, 922.6 and 1,023.7 nmol/l in the first, second, third and fourth quartiles, respectively; p < 0.0001), but this was not associated with a spontaneous reduction in mean baseline total homocysteine levels during the same time period (12.7, 14.3, 12.1 and 12.8 micromol/l in the first, second, third and fourth quartiles, respectively; p = 0.55). The homocysteine-lowering effect of the active VITATOPS trial medication at 6 months after randomization also did not change significantly between 1998 and 2002 (difference between randomized groups: -4.1, -4.1, -3.1 and -3.6 micromol/l in the first, second, third and fourth quartiles, respectively; p = 0.56).

CONCLUSIONS

The homocysteine-lowering effect of the active VITATOPS trial medication has not attenuated significantly in the past 5 years despite increasing voluntary fortification of foods with folic acid as reflected by a progressive rise in baseline folate status. These data suggest that in the continuing absence of a program of mandatory folate fortification of food in populations served by centers participating in the VITATOPS trial, the study will remain adequately powered to test the homocysteine-lowering hypothesis for which it was designed.

Homocysteine-Lowering Treatment With Folic Acid, Cobalamin, and Pyridoxine Does Not Reduce Blood Markers of Inflammation, Endothelial Dysfunction, or Hypercoagulability in Patients With Previous Transient Ischemic Attack or Stroke

Background and Purpose— Epidemiological and laboratory studies suggest that increasing concentrations of plasma homocysteine (total homocysteine [tHcy]) accelerate cardiovascular disease by promoting vascular inflammation, endothelial dysfunction, and hypercoagulability.

Methods— We conducted a randomized controlled trial in 285 patients with recent transient ischemic attack or stroke to examine the effect of lowering tHcy with folic acid 2 mg, vitamin B 12 0.5 mg, and vitamin B 6 25 mg compared with placebo on laboratory markers of vascular inflammation, endothelial dysfunction, and hypercoagulability.

Results— At 6 months after randomization, there was no significant difference in blood concentrations of markers of vascular inflammation (high-sensitivity C-reactive protein [ P =0.32]; soluble CD40L [ P =0.33]; IL-6 [ P =0.77]), endothelial dysfunction (vascular cell adhesion molecule-1 [ P =0.27]; intercellular adhesion molecule-1 [ P =0.08]; von Willebrand factor [ P =0.92]), and hypercoagulability (P-selectin [ P =0.33]; prothrombin fragment 1 and 2 [ P =0.81]; D-dimer [ P =0.88]) among patients assigned vitamin therapy compared with placebo despite a 3.7-μmol/L (95% CI, 2.7 to 4.7) reduction in total homocysteine (tHcy).

Conclusions— Lowering tHcy by 3.7 μmol/L with folic acid-based multivitamin therapy does not significantly reduce blood concentrations of the biomarkers of inflammation, endothelial dysfunction, or hypercoagulability measured in our study. The possible explanations for our findings are: (1) these biomarkers are not sensitive to the effects of lowering tHcy (eg, multiple risk factor interventions may be required); (2) elevated tHcy causes cardiovascular disease by mechanisms other than the biomarkers measured; or (3) elevated tHcy is a noncausal marker of increased vascular risk.

Cleavage of platelet endothelial cell adhesion molecule-1 (PECAM-1) in platelets exposed to high shear stress

Platelet endothelial cell adhesion molecule-1 (PECAM-1, CD31) is a 130 kDa transmembrane glycoprotein that belongs to the immunoglobulin superfamily and is expressed on the surface of endothelial cells, platelets, and other blood cells. Although the importance of this adhesion molecule in various cell-cell interactions is established, its functional role in platelets remains to be elucidated. In this study, we examined whether PECAM-1 underwent changes in platelets exposed to high shear stress. Platelet PECAM-1 was cleaved under high shear stress and was released into the extracellular fluid as a fragment with an approximate molecular weight of 118 kDa. The cleavage was inhibited by an anti-VWF MoAb, but not by recombinant VWF A1 domains. These findings suggest that the GPIb-VWF interaction is involved in PECAM-1 cleavage under high shear stress, and that the cleavage is independent of GPIb clustering by VWF multimers. Furthermore, EGTA or calpeptin inhibited PECAM-1 cleavage. This finding provides evidence for the involvement of calpain in PECAM-1 cleavage. Flow-cytometric analysis revealed that PECAM-1 expression on the platelet surface was decreased under high shear stress. This reduction occurred exclusively in a specific population of platelets, which corresponded to platelet-derived microparticles (PMP). In conclusion, PECAM-1 cleavage under high shear stress is closely related to the activation of calpain and the process of PMP formation mediated by the GPIb-VWF interaction.

Improving the accuracy of long-term prognostic estimates in hepatitis C virus infection

Obtaining unbiased estimates of HCV prognosis is difficult because of potential biases associated with study design and calculation methods. We propose a new method for estimating fibrosis progression rates. A Markov model with fibrosis health states (F0-F4) was created. The maximum likelihood method was used to estimate stage-specific progression rates. We compared the standard method to the new method using two well-known cohort studies. The known stage distribution at the end of follow-up was compared with stage predicted by the Markov model using both methods of calculating transition rates. We also compared rates obtained using both methods to known fibrosis rates in a series of Monte Carlo simulations. For Kenny-Walsh's study (1999), transition rates between F0-F1, F1-F2, F2-F3, and F3-F4 were 0.042, 0.045, 0.097 and 0.070 fibrosis units/year (new method) and 0.045 units/year (standard method). The new method predicted fibrosis stage and known transition rates in Monte Carlo simulations more accurately. The standard method underestimates 30-year cirrhosis rates by up to 40%. The new (Markov maximum likelihood or MML) method allows accurate estimation of stage-specific transition probabilities from the many studies in which only a single biopsy is available. Application of the method supports the hypothesis that rates of fibrosis vary between stages.

The autoimmune T and B cell repertoires in monozygotic twins discordant for myasthenia gravis

Two pairs of monozygotic twins, discordant for myasthenia gravis (MG) for more than 30 years, were studied regarding T cell and antibody reactivity against disease related autoantigens, the acetylcholine receptor, one idiotypic and one anti-idiotypic human monoclonal antibody. The healthy and myasthenic twins had very similar autoantibody repertoires. IgG fractions from both healthy and myasthenic twins had the same capacity to decrease the free acetylcholine receptor content in mice after passive transfer. In comparison with their myasthenic sisters, the healthy twins had lower T cell responses against the acetylcholine receptor.

Collagen platelet receptor polymorphisms integrin alpha2beta1 C807T and GPVI Q317L and risk of ischemic stroke

Several polymorphisms of integrin alpha2beta1 and glycoprotein (GP) VI that may modify platelet-collagen interactions or subsequent signaling have been described. We conducted a case-control study involving 180 stroke patients and 172 controls to determine whether the alpha2 C807T and GPVI Q317L polymorphisms were associated with an increased risk of ischemic stroke. We found no statistically significant differences in the distribution of alpha2 C807T and GPVI Q317L in patients and controls overall or after stratification by etiological subtype. The GPVI 317QQ genotype was found to be over-represented in a subgroup of patients >/=60 years compared to corresponding controls. However, this association did not remain significant after adjustment for other cardiovascular risk factors. Our results do not support a role for the integrin alpha2 C807T and GPVI Q317L polymorphisms in the development of first-ever ischemic stroke. However, larger studies are required to confirm this.

The platelet-activating factor receptor protects epidermal cells from tumor necrosis factor (TNF) alpha and TNF-related apoptosis-inducing ligand-induced apoptosis through an NF-kappa B-dependent process

A number of chemical mediators can induce human keratinocytes and epidermal-derived carcinomas to undergo apoptosis, or programmed cell death. Recent evidence suggests pro-inflammatory cytokines, such as interleukin-1 beta or transforming growth factor alpha, protects carcinomas from numerous pro-apoptotic stimuli. Platelet-activating factor (1-alkyl-2-acetyl-3-glycerophosphocholine; PAF) is a lipid mediator with pro-inflammatory effects on numerous cell types. Although PAF can be metabolized to other bioactive lipids, the majority of PAF effects occur through activation of a G protein-coupled receptor. Using a model system created by retroviral transduction of the PAF receptor (PAF-R) into the PAF-R-negative human epidermal cell line KB and the PAF-R-expressing keratinocyte cell line HaCaT, we now demonstrate that activation of the epidermal PAF-R results in protection from apoptosis induced by tumor necrosis factor (TNF) alpha or TNF-related apoptosis-inducing ligand. The PAF-mediated protection was inhibited by PAF-R antagonists, and protection did not occur in PAF-R-negative KB cells. Additionally, we show protection from TNFalpha- or TRAIL-induced apoptosis by PAF-R activation is dependent on the transcription factor nuclear factor (NF)-kappa B, because PAF-R activation-induced NF-kappa B and epidermal cells transduced with a super-repressor form of inhibitor kappa B were not protected by the PAF-R. These studies provide a mechanism whereby the epidermal PAF-R, and possibly other G protein-coupled receptors, can exert anti-apoptotic effects through an NF-kappa B-dependent process.

Controlled study of the use of autologous serum in dry eye patients

PURPOSE

To determine the efficacy and safety of topical autologous serum as a treatment of dry eye patients.

METHODS

A 2-month, prospective, single-masked, placebo-controlled study was conducted in patients with bilateral severe dry eye. One eye was randomized to receive the patient's own serum as a tear substitute, and the fellow eye received unpreserved normal saline solution as a placebo. Subjective symptoms and clinical parameters of dry eye including conjunctival impression cytology were assessed at baseline and 1 week, 1 month, and 2 months after treatment.

RESULTS

Twelve dry eye patients were enrolled. Both subjective symptoms (discomfort, foreign-body sensation, dryness, and photophobia), objective signs (fluorescein and rose bengal staining and conjunctival impression cytology) improved significantly in treated eyes compared with baseline. Control eyes also had improvement in symptoms, signs, and rose bengal staining compared with baseline. Neither Schirmer test results nor tear break-up time improved in either group. The means score of all parameters were improved in both groups, and the results of conjunctival impression cytology were better in treated eyes; however, these results are not significantly different. There were no serious adverse effects observed in this study.

CONCLUSIONS

There was a trend toward improvement in symptoms and signs of dry eye including cytologic changes after application of autologous serum in severe dry eye patients. However, this trend was not statistically significant. A larger scale study is warranted.

Risk factors, atherosclerosis, and cardiovascular disease among Aboriginal people in Canada: the Study of Health Assessment and Risk Evaluation in Aboriginal Peoples (SHARE-AP)

BACKGROUND

Little is known about the rates of cardiovascular disease (CVD), atherosclerosis, and their risk factors among Canada's Aboriginal people. To establish the relative prevalence of risk factors, atherosclerosis, and CVD, we undertook a population-based study among people of Aboriginal and European ancestry in Canada.

METHODS

We randomly recruited 301 Aboriginal people from the Six Nations Reservation, and 326 people of European origin from Hamilton, Toronto, and Edmonton, Canada. Clinical CVD was defined by history or electrocardiographic findings, atherosclerosis was measured by B-mode carotid ultrasonography, and conventional and new CVD risk factors were measured using standardised methods.

FINDINGS

Aboriginal people had significantly more carotid atherosclerosis (mean of the maximum intimal-medial thickness 0.82 (SD 0.20) mm vs 0.78 (0.20) mm, p=0.027), and had a higher frequency of CVD (18.5% vs 7.6%, p=0.00002) compared with Europeans. Aboriginal people had significantly higher rates of smoking, glucose intolerance, obesity, abdominal obesity, and substantially higher concentrations of fibrinogen, and plasminogen activator inhibitor-1. Aboriginal people had significantly higher rates of unemployment and a lower annual household income. For any given income level, Aboriginal people had higher rates of risk factors and CVD compared with the Europeans.

INTERPRETATION

A significant proportion of Aboriginal people live in poverty which is associated with high rates of CVD and CVD risk factors. Improvement of the socioeconomic status of Aboriginal people might be a key to reduce CVD in this group.

Reduction of cardiovascular risk by regression of electrocardiographic markers of left ventricular hypertrophy by the angiotensin-converting enzyme inhibitor ramipril

BACKGROUND

Electrocardiographic markers of left ventricular hypertrophy (LVH) predict poor prognosis. We determined whether the ACE inhibitor ramipril prevents the development and causes regression of ECG-LVH and whether these changes are associated with improved prognosis independent of blood pressure reduction.

METHODS AND RESULTS

In the Heart Outcomes Prevention Evaluation (HOPE) study, patients at high risk were randomly assigned to ramipril or placebo and followed for 4.5years. ECGs were recorded at baseline and at study end. We compared prevention/regression and development/persistence of ECG-LVH in the two groups and related these changes to outcomes. At baseline, 676 patients had LVH (321 in the ramipril group and 355 in the placebo group) and 7605 patients did not have LVH (3814 in the ramipril group and 3791 in the placebo group). By study end, 336 patients in the ramipril group (8.1%) compared with 406 in the placebo group (9.8%) had development/persistence of LVH; in contrast, 3799 patients in the ramipril group (91.9%) compared with 3740 in the placebo group (90.2%) had regression/prevention of LVH (P=0.007). The effect of ramipril on LVH was independent of blood pressure changes. Patients who had regression/prevention of LVH had a lower risk of the predefined primary outcome (cardiovascular death, myocardial infarction, or stroke) compared with those who had development/persistence of LVH (12.3% versus 15.8%, P=0.006) and of congestive heart failure (9.3% versus 15.4%, P<0.0001).

CONCLUSIONS

The ACE inhibitor ramipril decreases the development and causes regression of ECG-LVH independent of blood pressure reduction, and these changes are associated with reduced risk of death, myocardial infarction, stroke, and congestive heart failure.

Trends in health service delivery for cataract surgery at a large Australian ophthalmic hospital

PURPOSE

To evaluate trends in health service delivery for cataract surgery at the Royal Victorian Eye and Ear Hospital, Melbourne, Australia.

METHODS

A retrospective study was conducted of computerized hospital admissions for cataract surgery from July 1994 through June 1999. Main outcome measures included the annual number of cataract surgeries, waiting time, percentage of patients hospitalized overnight, length of overnight hospitalization, type of cataract surgery, surgery duration and total time in the operating theatre.

RESULTS

Although the annual number of patients undergoing cataract surgery increased from 3395 to 4796 over the 5-year study interval, there was a 13-day reduction in mean waiting time for public patients, a 30% reduction in overnight hospitalizations and a half-day reduction in length of hospitalization for all patients. There was also an increasing trend in use of phacoemulsification cataract extraction.

CONCLUSIONS

The health-care delivery for cataract surgery appears to have improved during the past 5 years at the Royal Victorian Eye and Ear Hospital.

Biodegradation of quinoline by gel immobilized Burkholderia sp

Burkholderia sp, a gram-negative, rod-shaped, aerobe, capable of degrading quinoline was immobilized in calcium alginate gel beads and used for degradation of quinoline in aqueous solution in the reactor. The optimal conditions for immobilization of the microorganism, such as alginate concentration, calcium ion concentration, initial cell loading, hardening time and bead size, were determined with a view to improving the quinoline degradation rate. The characteristics of quinoline degradation by immobilized microbial cells were investigated. The repeated use of immobilized cells for quinoline degradation was performed and the results revealed that the bioactivity of immobilized cells was stable over 100 h in the repeated batch cultivation for quinoline degradation.

Effects of ramipril on coronary events in high-risk persons: results of the Heart Outcomes Prevention Evaluation Study

BACKGROUND

In trials of patients with left ventricular dysfunction or heart failure, ACE inhibitor use was unexpectedly associated with reduced myocardial infarction (MI). Using the Heart Outcomes Prevention Evaluation (HOPE) trial data, we tested prospectively whether ramipril, an ACE inhibitor, could reduce coronary events and revascularization procedures among patients with normal left ventricular function.

METHODS AND RESULTS

In the HOPE trial, 9297 high-risk men and women, >/=55 years of age with previous cardiovascular disease or diabetes plus 1 risk factor, were randomly assigned to ramipril (up to 10 mg/d), vitamin E (400 IU/d), their combination, or matching placebos. During the mean follow-up of 4.5 years, there were 482 (10.4%) patients with clinical MI and unexpected cardiovascular death in the ramipril group compared with 604 (12.9%) in the placebo group [relative risk reduction (RRR), 21% (95% CI) (11,30); P<0.0003]. Ramipril was associated with a trend toward less fatal MI and unexpected death [4.0% versus 4.7%; RRR, 16% (-3, 31)] and with a significant reduction in nonfatal MI [5.6% versus 7.2%; RRR, 23% (9,34)]. Risk reductions in MI were documented in participants taking or not taking beta-blockers, lipid lowering, and/or antiplatelet agents. Although ramipril had no impact on hospitalizations for unstable angina [11.9% versus 12.2%; RRR, 3% (-9,14)], it reduced the risk of worsening and new angina [27.2% versus 30.0%; RRR, 12% (5,18); P<0.0014] and coronary revascularizations [12.5% versus 14.8%; RRR, 18%; (8,26) P<0.0005].

CONCLUSIONS

In this high-risk cohort, ramipril reduced the risk of MI, worsening and new angina, and the occurrence of coronary revascularizations.

Albuminuria and risk of cardiovascular events, death, and heart failure in diabetic and nondiabetic individuals

CONTEXT

Microalbuminuria is a risk factor for cardiovascular (CV) events. The relationship between the degree of albuminuria and CV risk is unclear.

OBJECTIVES

To estimate the risk of CV events in high-risk individuals with diabetes mellitus (DM) and without DM who have microalbuminuria and to determine whether levels of albuminuria below the microalbuminuria threshold increase CV risk.

DESIGN

The Heart Outcomes Prevention Evaluation study, a cohort study conducted between 1994 and 1999 with a median 4.5 years of follow-up.

SETTING

Community and academic practices in North and South America and Europe.

PARTICIPANTS

Individuals aged 55 years or more with a history of CV disease (n = 5545) or DM and at least 1 CV risk factor (n = 3498) and a baseline urine albumin/creatinine ratio (ACR) measurement.

MAIN OUTCOME MEASURES

Cardiovascular events (myocardial infarction, stroke, or CV death); all-cause death; and hospitalization for congestive heart failure.

RESULTS

Microalbuminuria was detected in 1140 (32.6%) of those with DM and 823 (14.8%) of those without DM at baseline. Microalbuminuria increased the adjusted relative risk (RR) of major CV events (RR, 1.83; 95% confidence interval [CI], 1.64-2.05), all-cause death (RR, 2.09; 95% CI, 1.84-2.38), and hospitalization for congestive heart failure (RR, 3.23; 95% CI, 2.54-4.10). Similar RRs were seen for participants with or without DM, even after adjusting for other CV risk factors (eg, the adjusted RR of the primary aggregate end point was 1.97 [95% CI, 1.68-2.31] in those with DM and 1.61 [95% CI, 1.36-1.90] in those without DM). Compared with the lowest quartile of ACR (<0.22 mg/mmol), the RRs of the primary aggregate end point in the second quartile (ie, ACR range, 0.22-0.57 mg/mmol) was 1.11 (95% CI, 0.95-1.30); third quartile, 1.38 (95% CI, 1.19-1.60; ACR range, 0.58-1.62 mg/mmol); and fourth quartile, 1.97 (95% CI, 1.73-2.25; ACR range, >1.62 mg/mmol) (P for trend <.001, even after excluding those with microalbuminuria). For every 0.4-mg/mmol increase in ACR level, the adjusted hazard of major CV events increased by 5.9% (95% CI, 4.9%-7.0%).

CONCLUSIONS

Our results indicate that any degree of albuminuria is a risk factor for CV events in individuals with or without DM; the risk increases with the ACR, starting well below the microalbuminuria cutoff. Screening for albuminuria identifies people at high risk for CV events.

Soy intake and the maintenance of peak bone mass in Hong Kong Chinese women

Our previous study on bone health among premenopausal women showed that bone mass consolidation is attained by the early 30s, and small loss of spinal bone mineral density (SBMD) occurs soon after peak bone mass attainment. Recent interest has been shown in the potential beneficial effects of phytoestrogens on bone health. However, data are lacking, particularly in Asian women. This study aims to investigate the effect of soy isoflavones intake on the maintenance of peak bone mass in a cohort of 132 women aged 30-40 years who were followed up for 3 years. Baseline measurements of SBMD (L2-L4) were obtained using dual-energy X-ray densitometry, and dietary intake of soy foods and other key nutrients, including dietary calcium, were obtained through a quantitative food frequency method. Information on body measurements; physical activity (PA), weight-bearing activity in particular; age of menarche; and number of pregnancies were obtained at baseline. Repeated measurements of SBMD were obtained yearly for a further 3 years with an average follow-up time of 38 months. Analyses were performed on 116 subjects with at least three SBMD measurements (at baseline, 3-year follow-up, and at least one measurement during follow-up). The individual SBMD regression slope was computed for each of the subjects. Soy isoflavones consumption was categorized as quartiles of intake. We observed a significant difference in the SBMD individual regression slopes between women belonging to the fourth and first soy isoflavones intake quartiles. The positive effect of soy isoflavones on SBMD remained after adjusting for age and body size (height, weight, and bone area). Multiple linear regression analysis including the other known covariates (lean body mass, PA, energy adjusted calcium, and follow-up time) showed that soy isoflavones, together with these variables, accounted for 24% of the variances of the SBMD individual regression slope. This longitudinal study shows that soy intake had a significant effect on the maintenance of SBMD in women aged 30-40 years. The effects of phytoestrogens on bone health should be explored further in a population with habitual dietary soy but low calcium intake.

Interleukin-10 gene promoter polymorphisms in multiple myeloma

Multiple myeloma (MM) is a B-cell malignancy characterized by an accumulation of malignant plasma cells in the bone marrow. It is unclear whether genetic background could have an etiological impact on MM or influence the course of the disease. Interleukin-10 (IL-10) has been implicated in the growth and differentiation of normal B cells, and has also been shown to enhance the proliferation of MM cells. To address the putative involvement of IL-10 genetic variation in MM, we analyzed previously defined loci for bi-allelic polymorphism at position -1082 and two microsatellite loci (IL10.G and IL10.R) in the IL-10 promoter region. Seventy-three patients with MM, 27 with monoclonal gammopathy of undetermined significance, and 109 ethnically matched individuals as controls were included in the study. Significantly increased frequencies of the IL10.G genotype 136/136 and the IL10.R genotype 112/114, in addition to a decreased frequency of the IL10.R genotype 114/116, were found among the MM patients. Increased production of IL-10 was detected in the supernatants of lipopolysaccharide-stimulated peripheral blood mononuclear cells from MM patients who were homozygotes (136/136) and heterozygotes (136/non-136) for the IL10.G allele 136, as compared with the other IL10.G genotype carriers (non-136/non-136). These results suggest that the genetic variation in the IL-10 promoter region may play a role in the development of MM.

[A comparison between a submerged membrane bioreactor and a conventional activated sludge process]

A comparison between a submerged membrane bioreactor (MBR) and a conventional activated sludge process (CAS) was carried out under similar operational conditions. MBR demonstrated a more stable and excellent effluent quality than CAS. Its effluent COD concentration was 55.5 mg/L on average, much lower than that of CAS (79.7 mg/L). Soluble microbial products accumulated in the MBR during the first 120 days in operation due to membrane interception of macromolecules, but these accumulated substances were degraded at last with microbial acclimation. No similar phenomenon was observed in the CAS system. Compositions of the CAS effluent, MBR supernatant and membrane permeate were found quite different. In the CAS effluent and MBR supernatant, both macromolecules with MW > 60,000 and small molecules with MW < 3,000 were dominant and macromolecules had a much larger occupation in the MBR supernatant. In the membrane permeate, however, small molecules with MW < 3,000 were the major component. The relatively small floc size in the MBR was proved favorable to improve oxygen transfer rate.

Idiotype-specific cytotoxic T lymphocytes in multiple myeloma: evidence for their capacity to lyse autologous primary tumor cells

Multiple myeloma (MM) is a B-cell malignancy. The monoclonal immunoglobulin, secreted by myeloma plasma cells, carries unique antigenic determinants (idiotype [Id]) that can be regarded as a tumor-specific antigen. Id-based immunotherapy has been explored in myeloma patients for the purpose of enhancing or inducing Id-specific immune responses that might lead to tumor destruction. However, despite some evidence obtained from mouse plasmacytoma models, it is still unclear whether Id-specific immunity may play a role in the regulation of tumor cells in MM. In the current study, using dendritic cells (DCs) as antigen-presenting cells, autologous Id-specific cytotoxic T lymphocyte (CTL) lines containing both CD4+ and CD8+ T cells were generated from myeloma patients. The results show that Id-specific CTLs not only recognized and lysed autologous Id-pulsed DCs but also significantly killed the autologous primary myeloma cells. The cytotoxicity against the primary tumor cells was major histocompatibility complex (MHC) class I- and, to a lesser extent, class II-restricted, indicating that myeloma cells could process Id protein and present Id peptides in the context of their surface MHC molecules. Furthermore, the CTLs lysed the target cells mainly through the perforin-mediated pathway because Concanamycin A, but not Brefeldin A-the selective inhibitors for perforin- or Fas-mediated pathways-abrogated the cytolytic activity of the cells. These CTLs secreted predominantly interferon-gamma and tumor necrosis factor-alpha on antigen stimulation, indicating that they belong to the type-1 T-cell subsets. Taken together, these findings represent the first demonstration that Id-specific CTLs are able to lyse autologous tumor cells in MM and, thus, provide a rationale for Id-based immunotherapy in the disease.

Telomerase activity in plasma cell dyscrasias

Activation of telomerase is essential for in vitro cellular immortalization and tumorigenesis. In the present study, we investigated telomerase activation and its implications in plasma cell dyscrasias including monoclonal gammopathy of undetermined significance (MGUS), multiple myeloma (MM) and plasma cell leukaemia (PCL). All 5 patients with MGUS exhibited normal levels of telomerase activity in their plasma cells. Elevated telomerase activity was found in the samples from 21/27 patients with MM and 4/4 with PCL. In addition, 4 myeloma cell lines all expressed high levels of telomerase activity. The expression of telomerase reverse transcriptase (hTERT) and telomerase RNA template (hTER) was positively associated with the levels of telomerase activity in MM/PCL. Tankyrase expression was upregulated, concomitant with the induction of hTERT and activation of telomerase in MM/PCL. The present findings indicate that MGUS cells may not be immortalized and that activation of telomerase plays a role in the malignant transformation from MGUS to MM.