Efficacy of repetitive transcranial magnetic stimulation for post-stroke depression: a systematic review and meta-analysis of randomized clinical trials.

We aimed to conduct a meta-analysis to evaluate the efficacy of repetitive transcranial magnetic stimulation (rTMS) in patients with post-stroke depression (PSD). Six relevant electronic databases (PubMed, CENTRAL, Embase, Web of Science, CINAHL, and PsycINFO) were searched. Randomized controlled trials (RCTs) that compared rTMS with control condition for PSD were included. The mean change in depression symptom scores was defined as the primary efficacy outcome. Secondary outcomes included the remission rate of depression, stroke recovery, and cognitive function recovery. In total, 7 RCTs with 351 participants were included. At post-treatment, rTMS was significantly more effective than the control condition, with a standardized mean difference (SMD) of -1.15 (95%CI: -1.62 to -0.69; P<0.001, I2=71%) and remission with an odds ratio (OR) of 3.46 (95%CI: 1.68 to 7.12; P<0.001; I2=11%). As for stroke recovery, rTMS was also better than the control condition (SMD=-0.67, 95%CI: -1.02 to -0.32; P<0.001). However, no significant difference was found for cognitive function recovery between the two groups (SMD=4.07, 95%CI: -1.41 to 9.55; P=0.15). To explore the potential moderators for the primary outcome, a series of subgroup and sensitivity analyses were performed. The results implied that rTMS may be more effective in Asian samples than in North American samples (P=0.03). In conclusion, from the current evidence in this study, rTMS could be an effective treatment for patients with PSD. Further clinical studies with larger sample sizes and clearer subgroup definitions are needed to confirm these outcomes.

Efficacy of repetitive transcranial magnetic stimulation for post-stroke depression: a systematic review and meta-analysis of randomized clinical trials

We aimed to conduct a meta-analysis to evaluate the efficacy of repetitive transcranial magnetic stimulation (rTMS) in patients with post-stroke depression (PSD). Six relevant electronic databases (PubMed, CENTRAL, Embase, Web of Science, CINAHL, and PsycINFO) were searched. Randomized controlled trials (RCTs) that compared rTMS with control condition for PSD were included. The mean change in depression symptom scores was defined as the primary efficacy outcome. Secondary outcomes included the remission rate of depression, stroke recovery, and cognitive function recovery. In total, 7 RCTs with 351 participants were included. At post-treatment, rTMS was significantly more effective than the control condition, with a standardized mean difference (SMD) of -1.15 (95%CI: -1.62 to -0.69; P<0.001, I2=71%) and remission with an odds ratio (OR) of 3.46 (95%CI: 1.68 to 7.12; P<0.001; I2=11%). As for stroke recovery, rTMS was also better than the control condition (SMD=-0.67, 95%CI: -1.02 to -0.32; P<0.001). However, no significant difference was found for cognitive function recovery between the two groups (SMD=4.07, 95%CI: -1.41 to 9.55; P=0.15). To explore the potential moderators for the primary outcome, a series of subgroup and sensitivity analyses were performed. The results implied that rTMS may be more effective in Asian samples than in North American samples (P=0.03). In conclusion, from the current evidence in this study, rTMS could be an effective treatment for patients with PSD. Further clinical studies with larger sample sizes and clearer subgroup definitions are needed to confirm these outcomes.

Sea level rise, surface warming, and the weakened buffering ability of South China Sea to strong typhoons in recent decades.

Each year, a number of typhoons in the western North Pacific pass through the Luzon Strait into South China Sea (SCS). Although the storms remain above a warm open sea, the majority of them weaken due to atmospheric and oceanic environments unfavorable for typhoon intensification in SCS, which therefore serves as a natural buffer that shields the surrounding coasts from potentially more powerful storms. This study examines how this buffer has changed over inter-decadal and longer time scales. We show that the buffer weakens (i.e. greater potential for more powerful typhoons) in negative Pacific Decadal Oscillation (PDO) years, as well as with sea-level-rise and surface warming, caused primarily by the deepening of the ocean's 26 °C isotherm Z 26 . A new Intensity Change Index is proposed to describe the typhoon intensity change as a function of Z 26 and other environmental variables. In SCS, the new index accounts for as high as 75% of the total variance of typhoon intensity change.

No evidence of association of the osteocalcin gene HindIII polymorphism with bone mineral density in Chinese women.

Osteoporosis is a major health problem, mainly characterized by low bone mineral density (BMD). Osteocalcin (also known as BGP, for bone Gla protein) is a significant biomarker of bone turnover and thus the BGP gene has been considered as an important candidate gene for osteoporosis. A few studies on the relationship between variants of the BGP gene and BMD variation, via traditional association and/or linkage methods, have yielded conflicting results. In the present study, we simultaneously tested linkage and/or association of the BGP HindIII polymorphism with BMD in a large cohort of pre-menopausal Chinese women. A total of 1,263 subjects from 402 Chinese nuclear families were examined. Each family consists of both parents and at least one daughter aged between 20-45 years. BMDs at the lumbar spine and hip were measured by dual-energy X-ray absorptiometry (DXA). Using the QTDT (quantitative transmission disequilibrium test) program, we did not detect significant evidence of linkage or association between the BGP HindIII polymorphisms and the BMD variation at any skeletal site. Our data do not support the BGP gene having a major effect on BMD variation in pre-menopausal Chinese women.

A survey of haplotype variants at several disease candidate genes: the importance of rare variants for complex diseases.

BACKGROUND: The haplotype based association method offers a powerful approach to complex disease gene mapping. In this method, a few common haplotypes that account for the vast majority of chromosomes in the populations are usually examined for association with disease phenotypes. This brings us to a critical question of whether rare haplotypes play an important role in influencing disease susceptibility and thus should not be ignored in the design and execution of association studies. METHODS: To address this question we surveyed, in a large sample of 1873 white subjects, six candidate genes for osteoporosis (a common late onset bone disorder), which had 29 SNPs, an average marker density of 13 kb, and covered a total of 377 kb of the DNA sequence. RESULTS: Our empirical data demonstrated that two rare haplotypes of the parathyroid hormone (PTH)/PTH related peptide receptor type 1 and vitamin D receptor genes (PTHR1 and VDR) with frequencies of 1.1% and 2.9%, respectively, had significant effects on osteoporosis phenotypes (p = 4.2 x 10(-6) and p = 1.6 x 10(-4), respectively). Large phenotypic differences (4.0 approximately 5.0%) were observed between carriers of these rare haplotypes and non-carriers. Carriers of the two rare haplotypes showed quantitatively continuous variation in the population and were derived from a wide spectrum rather than from one extreme tail of the population phenotype distribution. CONCLUSIONS: These findings indicate that rare haplotypes/variants are important for disease susceptibility and cannot be ignored in genetics studies of complex diseases. The study has profound implications for association studies and applications of the HapMap project.

Vitamin D receptor gene polymorphisms are linked to and associated with adult height.

BACKGROUND: The vitamin D receptor (VDR) gene is important to human stature, as it mediates metabolic pathways, calcium homeostasis, and phosphate homeostasis, which influence growth. METHODS: We examined the relationship between VDR and adult height in 1873 white subjects from 406 nuclear families. Four SNPs, namely -4817A/G at intron 1, FokI C/T at exon 2 start codon, BsmI A/G at intron 8, and TaqI T/C at exon 9 in VDR were tested for linkage and association with adult height variation by the program QTDT (quantitative transmission disequilibrium test). The bT haplotype of the BsmI and TaqI loci was further tested for its association with height in unrelated samples randomly chosen from the 406 nuclear families by traditional population association methods. RESULTS: All four tested SNPs were linked to adult height. Within family associations with height were detected at BsmI and TaqI loci (p = 0.048 and 0.039, respectively). Analyses based on BsmI/TaqI haplotypes also revealed evidence for linkage (p = 0.05) and association (p = 0.001) with height. The bT haplotype was significantly associated with higher adult height (p = 0.033, within family association test). Such an association might be female specific and influenced by menstrual status. CONCLUSIONS: Our results strongly suggest that VDR may be linked to and associated with adult height variation in white populations.

Common variants at the PCOL2 and Sp1 binding sites of the COL1A1 gene and their interactive effect influence bone mineral density in Caucasians.

BACKGROUND: Osteoporosis, mainly characterised by low bone mineral density (BMD), is a serious public health problem. The collagen type I alpha 1 (COL1A1) gene is a prominent candidate gene for osteoporosis. Here, we examined whether genetic variants at the COL1A1 gene can influence BMD variation. METHODS: BMD was measured at nine skeletal sites in 313 Caucasian males and 308 Caucasian females. We screened four single nucleotide polymorphisms (SNPs) at the COL1A1 gene: PCOL2 (-1997 G/T) in the promoter, Sp1 (1546 G/T) in the intron 1, Gly19Cys (3911 G/A) in exon 8, and Ala897Thr (13 773 G/A) in exon 45. Univariate and multivariate association approaches were used in the analyses. RESULTS: In multivariate analyses, we found a strong association between the PCOL2 SNP and BMD (p = 0.007 to 0.024) and a suggestive association between the Sp1 SNP and BMD (p = 0.023 to 0.048) in elderly Caucasian females. Interestingly, the interaction of these two SNPs was highly significantly associated with BMD variation (p = 0.001 to 0.003). The haplotype GG at the two SNPs had, on average, 2.7% higher BMD than non-carriers (p = 0.006 to 0.026). CONCLUSIONS: Our data suggested that the common genetic variants at the PCOL2 and Sp1 sites, and importantly, their interactive effects, may contribute to BMD variation in elderly Caucasian females. Further studies are necessary to delineate the mechanisms underlying the effects of these common variants on BMD variation and to test their clinical relevance for general populations. In addition, our study highlighted the importance of multivariate analyses when multiple correlated phenotypes are under study.

A genome-wide linkage scan for bone mineral density in an extended sample: evidence for linkage on 11q23 and Xq27.

BACKGROUND: Osteoporosis is a major public health problem, mainly quantified by low bone mineral density (BMD). The majority of BMD variation is determined by genetic effects. A pilot whole genome linkage scan (WGS) was previously reported in 53 white pedigrees with 630 subjects. Several genomic regions were suggested to be linked to BMD variation. OBJECTIVE: To substantiate these previous findings and detect new genomic regions. METHODS: A WGS was conducted on an extended sample where the size was almost tripled (1816 subjects from 79 pedigrees). All the subjects were genotyped with 451 microsatellite markers spaced approximately 8.1 cM apart across the human genome. Two point and multipoint linkage analyses were carried out using the variance component method. RESULTS: The strongest linkage signal was obtained on Xq27 with two point LOD scores of 4.30 for wrist BMD, and 2.57 for hip BMD, respectively. Another important region was 11q23, which achieved a maximum LOD score of 3.13 for spine BMD in multipoint analyses, confirming the results on this region in two earlier independent studies. Suggestive linkage evidence was also found on 7p14 and 20p12. CONCLUSIONS: Together with the findings from other studies, the current study has further delineated the genetic basis of bone mass and highlights the importance of increasing sample size to confirm linkage findings and to identify new regions of linkage.

A second-stage genome scan for QTLs influencing BMD variation.

Low bone mineral density (BMD) is a major risk factor for osteoporotic fracture. To identify genomic regions harboring quantitative trait loci (QTLs) contributing to BMD variation, we performed a two-stage genome screen. The first stage involved genotyping of a sample of 53 pedigrees with 630 individuals using 400 microsatellite markers spaced at approximately 10-cM intervals throughout the genome. Ten genomic regions with multi- and/or two-point LOD scores greater than 1.5 were observed. In the present second-stage study, 60 microsatellite markers, with a mean spacing of about 5 cM, were genotyped in these regions in an expanded sample of 79 pedigrees that contained 1816 subjects. Each pedigree was ascertained through a proband with extreme BMD at the hip or spine. BMD at the spine (L1-4), hip (the femoral neck, trochanter, and intertrochanteric region), and wrist (the ultradistal region) was measured by dual-energy X-ray absorptiometry (DXA) and was adjusted for age, sex, height, and weight. Two-point and multipoint linkage analyses were performed for each BMD site using statistical genetic methods that are implemented in the computer package SOLAR. Several regions (7q11, 10q26, 12q13, and 12q24) achieved LOD scores in excess of 1 in the second-stage followup study. The current results replicate some of our previous linkage findings and also highlight some of the difficulties facing microsatellite linkage mapping for complex human diseases.

Evidence for a major gene for bone mineral density/content in human pedigrees identified via probands with extreme bone mineral density.

Bone mineral content (BMC) and/or bone mineral density (BMD, i.e. BMC scaled by bone size) are major determinants for osteoporosis, which is a serious health problem. The major determinant of variation in BMD/BMC is genetic. The few studies now available are inconsistent in the identification and/or even in the existence of major gene(s) for BMD/BMC. In 51 human pedigrees with 941 individuals (526 measured for phenotypes) identified via probands with extreme BMD values, we performed complex segregation analyses to test the existence of a genetic locus with a major effect on BMD/BMC variation. We analyzed BMD and BMC at the spine, hip and wrist jointly by employing, as the study phenotype, factor scores (FS) of the principle component that explains approximately 75% of the total BMD/BMC variation at the three sites. The results indicate that a major gene exists with a codominant effect that is responsible for approximately 16% of the FS variation when adjusted for significant effects of sex, body weight and age. A significant genotype-x-sex-x-age interaction was found, which may explain approximately 14% of the FS variation after adjusting for body weight. Testing of various models did not provide support for shared familial environmental effects but suggested the existence of residual polygenic effects, which may explain approximately 50% of the FS variation when adjusting for sex, body weight and age. This study indicates a promising aspect of studies to identify a major gene for BMD/BMC variation in our pedigrees identified via extreme probands.

Characterization of genetic and lifestyle factors for determining variation in body mass index, fat mass, percentage of fat mass, and lean mass.

In this study, we simultaneously characterized genetic and lifestyle factors (exercise, smoking, and alcohol consumption) in determining variation in body mass index (BMI), fat mass, percentage of fat mass (PFM), and lean mass while adjusting for the effects of age and sex. Six hundred fifty-eight Caucasian individuals from 48 pedigrees were studied for BMI. Among these individuals, 289 from 38 pedigrees were studied for fat mass, PFM, and lean mass measured by dual X-ray absorptiometry (DXA). After adjusting for age, sex, and lifestyle factors, the heritabilities (h(2)) of BMI, fat mass, PFM, and lean mass ranged from 0.52 to 0.57 with associated standard errors ranging from 0.09 to 0.14. After accounting for significant sex and age effects, exercise had significant effects for all the phenotypes studied, and the effects of smoking and alcohol consumption were not significant. Therefore, significant proportions of variation in BMI, fat mass, PFM, and lean mass were under genetic control, and exercise had a significant effect in reducing BMI, fat mass, and PFM and in increasing lean mass. This study warrants further genetic linkage analyses to search for genes for the obesity-related phenotypes measured by DXA in our population.

Mifepristone regulates expression of apoptosis related genes Fas and FasL in mouse endometrium.

AIM: To investigate the anti-implantation mechanism of mifepriston. METHODS: In situ hybridization and immunohistochemistry were applied to determine mRNA and protein. RESULTS: After mifepriston injection, the number of implantation sites were obviously reduced, mifepriston could inhibit the embryo implantation in mouse. The expression of apoptosis related genes, Fas and FasL, in mouse endometrium was also decreased after mifepriston treatment. CONCLUSION: The expression of apoptosis related genes Fas and FasL is regulated by mifepriston and the inhibitory effect of mifepriston on the embryo implantation may be mediated by action on the Fas/FasL system.

Is population bone mineral density variation linked to the marker D11S987 on chromosome 11q12-13?

Our purpose is to test linkage of human chromosome 11q12-13 to BMD variation. Chromosome 11q12-13 has been linked to three BMD-related phenotypes that are inherited as Mendelian traits in human pedigrees: an autosomal dominant high bone mass trait, autosomal recessive osteoporosis pseudoglioma, and autosomal recessive osteopetrosis. A sibling pair study with 374 sibships showed significant linkage of D11S987 to normal BMD variation, with a maximum logarithm of odds score of 3.5. However, a subsequent linkage study with a total of 595 sibling pairs demonstrated reduced significance for linkage of D11S987 to bone mineral density variation, with a logarithm of odds score less than 2.2. We genotyped five markers in a genomic region of approximately 27 cM centering on D11S987 and measured bone mineral density and other traits (weight, etc.) for 635 individuals from 53 human pedigrees. Each of these pedigrees was ascertained through a proband with bone mineral density Z-scores less than -1.28 at the hip or spine. Adjusting for age, sex, and weight as covariates, we performed two-point and multipoint linkage analyses using the variance component linkage analysis method implemented in Sequential Oligogenic Linkage Analysis Routines. We found little evidence of linkage of these five markers to bone mineral density at the spine, hip, wrist and total body bone mineral content. The maximum logarithm of odds score at these five markers was 0.25, and the maximum logarithm of odds score at D11S987 was 0.15. Therefore, although we cannot exclude the linkage of D11S987 region to bone mineral density variation, there is no evidence for linkage of the marker D11S987 on human chromosome 11q12-13 to bone mineral density variation in our study population.

Effects of Kampo formulations (Chinese herbal medicine traditionally used in Japan) on event-related electric potentials.

Contingent negative variation (CNV) is a brain function test of the central nervous system in reference to attention, will preparation and motivation. We compared the neuropharmacological effects of 6 main Kampo formulations (1. Mao-to: MA HUANG TANG; 2. Shimbu-to: ZHEN WU TANG; 3. Ninjin-to: REN SHEN TANG; 4. Shigyaku-san: SI NI SAN; 5. Keishi-to: GUI ZHI TANG; and 6. Shimotsu-to: SI WU TANG) on CNV. Mao-to induced significant decrease of CNV in 90 minutes after oral administration. Shimbu-to showed a tendency to increase CNV in 90 minutes after oral administration. Shimotsu-to also induced a transient tendency to increase CNV in 60 minutes after oral administration. Keishi-to showed a decrease of CNV in the early stage of the experiment, while Ninjin-to and Shigyaku-san showed no changes of CNV. From these, it may be concluded that Mao-to and Keishi-to induce sedation of brain function, but Shimbu-to and Shimotsu-to show activation, while Ninjin-to and Shigyaku-san show no changes of brain function regarding CNV related brain function. Furthermore, the time courses of CNV changes were different within the same group (sedation or activation) of Kampo formulations.

Effect of Kampo formulations (traditional Chinese medicine) on circulatory parameters.

The pharmacological action of 6 main Kampo formulations (1.Mao -to: [Japanese pictograph see text] MA HUANG TANG; 2. Shimbu -to: [Japanese pictograph see text]: ZHEN WU TANG; 3. Ninjin -to: [Japanese pictograph see text] : REN SHEN TANG; 4.Shigyaku-san: [Japanese pictograph see text] : SI NI SAN; 5.Keishi-to: Japanese pictograph see text] : GUI ZHI TANG; 6. Shimotsu - to: [Japanese pictograph see text] : SI WU TANG) on circulatory and autonomic nervous system were studied. 7 healthy adult males( age, 22.3 +/- 1.8 years old ) had 6 basic Kampo formulations, followed by noninvasive measurement of systolic blood pressure (SBP), mean blood pressure (MBP), diastolic blood pressure (DBP), heart rate (HR), stroke volume (SV), cardiac output (CO ), cardiacindex (CI), total peripheral resistance (TPR) by means of systolic area method of brachialsphygmography, every 30 minutes for 2 hours. As results, Mao - to induced an increase of BP,HR,SV,CO and CI, but a decrease of TPR. Keishi - to induced an increase of SBP and SV, and Shimotsu-to induced an increase of DBP and MBP, HR was slowed during former period after oral administration of Shigyaku - san, and later period after oral administration of Shimbu-to and Shimotsu-to. Regarding autonomic activity, Mao-to(former period of experiment ), Shimbu - to and Shimotsu-to induced supression of sympathetic activity, on the other hand, Mao-to (later period of experiment ) and Shiyaku - san showed a tendency of parasympathomimetic action. Mao -to induced the strongest activation of circulatory system of 6 main farmulations, and showed change of autonomic nervous activity, however, the change of circulatory and automonic nervous activity were not coincident each other. It was speculated that comprehensive mechanism of Mao-to were not only dependent of ephedrin, main active constituent of Mao, but also dependent on Keishi's vasodilatory action in it. Ninjin -to showed no actions on circulatory or autonomic system. This is indicated that there are difference of actions on circulatory and autonomic nervous system among 6 main Kampo fromulations.

Interleukin-6-induced inhibition of multiple myeloma cell apoptosis: support for the hypothesis that protection is mediated via inhibition of the JNK/SAPK pathway.

The mechanism by which interleukin-6 (IL-6) protects multiple myeloma (MM) plasma cells from apoptosis induced by anti-fas antibodies and dexamethasone was studied. Anti-apoptotic concentrations of IL-6 had no effect on cell-cycle distribution or activation of RAF-1 or ERK in dexamethasone- or anti-fas-treated 8226 and UCLA #1 MM cell lines. However, IL-6-dependent protection of viability correlated with an inhibition of dexamethasone- and anti-fas-induced activation of jun kinase (JNK) and AP-1 transactivation. To test the hypothesis that cytokine-induced protection was mediated through inhibition of JNK/c-jun, we also inhibited c-jun function in 8226 cells via introduction of a mutant dominant negative c-jun construct. Mutant c-jun-containing MM cells were also resistant to anti-fas-induced apoptosis but were significantly more sensitive to dexamethasone-induced apoptosis. These results support the notion that IL-6 protects MM cells against anti-fas through its inhibitory effects on JNK/c-jun but indicate protection against dexamethasone occurs through separate, yet unknown pathways.

Evidence against the hypothesis that BCL-2 inhibits apoptosis through an anti-oxidant effect.

We contrasted possible protection against apoptosis afforded by either BCL-2 expression or anti-oxidant inhibitors in the same tumor target challenged by two distinct triggers of apoptosis. Exposure of L929 fibroblasts to tumor necrosis factor (TNF) or etoposide (VP-16) induced apoptotic death with similar kinetics. Enforced expression of BCL-2 significantly protected against apoptosis induced by VP-16 but had no effect against TNF-induced apoptosis. In contrast, the anti-oxidants desferrioxamine, butylated hydroxyanisol and N-acetyl cysteine all inhibited TNF-induced apoptosis in a concentration-dependent fashion. Although exposure to VP-16 resulted in a significant generation of intracellular oxyradicals, the above three anti-oxidant inhibitors had no effect on VP-16-induced apoptotic death. Interestingly, enforced expression of BCL-2 also inhibited the ability of VP-16 to generate oxy-radicals and to depress intracellular glutathione levels. These results indicate that BCL-2 can exert anti-oxidant effects but argue against the hypothesis that these effects are critical to its protection against apoptosis.

Apoptotic vs. nonapoptotic cytotoxicity induced by hydrogen peroxide.

The regulation of cellular cytotoxicity induced by hydrogen peroxide (H2O2) over a wide concentration range was assessed. Three distinct patterns were detected: the highest concentrations (> 10 mM) rapidly induced a necrotic form of death characterized by smeared patterns of DNA digestion and morphological evidence of primary cytoplasm and plasma membrane damage; In contrast, 10 and 5 mM H2O2 induced endonucleosomal DNA digestion concurrently with cytotoxicity and target cell death was associated with morphologic evidence of apoptosis. Apoptosis was inhibited by cycloheximide, emetine, aminobenzamide (ABA), aurintricarboxylic acid, and calcium depletion. The lowest concentrations of H2O2 (0.5 and 0.1 mM)-induced delayed cytotoxicity (at 24 or 48 hr), which was not associated with DNA ladder formation or morphologic evidence of apoptosis, but was inhibited by ABA. Enforced expression of BCL-2 induced resistance to 0.5 and 0.1 mM H2O2 but had no effect on cytotoxicity induced by 5 and 10 mM. Exposure of isolated nuclei to H2O2 in the absence of calcium or magnesium failed to induce endonucleosomal fragmentation. These data indicate that distinct pathways of H2O2-induced cytotoxicity can be distinguished by their different concentration dependences, and that BCL-2 can protect against some forms of H2O2-induced cytotoxicity.

Upregulated expression of BCL-2 in multiple myeloma cells induced by exposure to doxorubicin, etoposide, and hydrogen peroxide.

Enhanced expression of the antiapoptotic gene BCL-2 may participate in chemoresistance. To ascertain if multiple myeloma cells surviving exposure to chemotherapy alter their BCL-2 expression, we treated the myeloma cell lines 8226, IM-9, and U266 as well as a primary myeloma cell culture with various injurious agents. Doxorubicin, etoposide, and hydrogen peroxide consistently induced a concentration- and time-dependent upregulation of BCL-2 expression in all myeloma target cell types assayed by flow cytometry and Western blot analysis. In contrast, serum starvation, dexamethasone, and anti-fas antibodies had no effect on expression. Enhanced expression of BCL-2 was relatively selective as treatments had no effect on expression of Ig light chains, BCL-X, or actin. An reverse transcriptase-polymerase chain reaction assay showed increased levels of BCL-2 RNA in 8226 cells as early as 4 hours after treatment with doxorubicin at a time when cell recoveries were not decreased. Thus, doxorubicin stimulates BCL-2 expression in individual 8226 cells rather than simply allowing a selected survival of high BCL-2-expressing cells in culture. Doxorubicin-treated 8226 cells with upregulated BCL-2 expression were relatively resistant to a second exposure of doxorubicin. In addition, BCL-2-transfected IM-9 cells, with enhanced expression of BCL-2 which was comparable to that achieved by initial exposure to doxorubicin, were resistant to doxorubicin and etoposide cytotoxicity. These data suggest that exposure to chemotherapeutic agents may enhance BCL-2 expression in surviving myeloma cells and contribute to acquired chemoresistance.