Biomedical subjects

K S Han

Publications and source records attributed to K S Han.

At least 19 recordsLinked to original sources

PubMed2006

Effects of Lactobacillus strains on cancer cell proliferation and oxidative stress in vitro.

AIMS: The objective of this study was to assess in vitro, whether heat-killed (HK) lactic acid bacteria cells and fractionations of HK cells could suppress the viability of human cancer cells and inhibit the cytotoxicity associated with oxidative stress. METHODS AND RESULTS: Among the strains, the HK cells of Lactobacillus acidophilus 606 and Lactobacillus casei ATCC 393 exhibited the most profound inhibitory activity in all of the tested cell lines. HK cells of L. acidophilus 606 were determined to be less toxic to healthy human embryo fibroblasts (hEF cells) than were HK cells of L. casei ATCC 393. The soluble polysaccharides from L. acidophilus 606 evidenced the most effective anticancer activity, but inhibited hEF cell growth by only 20%. The soluble polysaccharides from L. acidophilus 606 were partly observed to induce apoptosis in the HT-29 cells by DNA fragmentation and propidium iodine staining. Both the HK cells of L. acidophilus 606 and the soluble polysaccharide components of this strain also exhibited potent antioxidative activity. CONCLUSIONS: Our findings suggest that the soluble polysaccharide fraction from L. acidophilus 606 may constitute a novel anticancer agent, which manifests a high degree of selectivity for human cancer cells and antioxidative agent in the food industry. SIGNIFICANCE AND IMPACT OF THE STUDY: These soluble polysaccharide components from Lactobacillus may be applied to various foods, and used as adjuncts for cancer therapy and prevention.

Antineoplastic Agents↗

PubMed2005

Frameless stereotactic placement of ventriculoperitoneal shunts in undersized ventricles: a simple modification to free-hand procedures.

The aim of this report is to introduce a simple modification to the free-hand frameless stereotactic placement of ventriculoperitoneal shunts in undersized ventricles. In this technical note, we describe our experience with ventricular catheter placement in two children suffering from shunt dependent idiopathic intracranial hypertension using an image-guided instrument holder with a catheter guide. In both patients, the surgical procedure proved to be easy and accurate, with good initial clinical results. The use of an image-guided instrument holder is a modification to the free-hand frameless stereotactic placement of ventriculoperitoneal shunts in undersized ventricles.

Cerebral Ventricles↗

PubMed2005

Optimization of technical conditions for the transformation of Lactobacillus acidophilus strains by electroporation.

AIMS: To optimize the conditions for electroporating foreign plasmid DNA into Lactobacillus acidophilus ATCC 43121. METHODS AND RESULTS: The conditions of electroporation were optimized to improve the transformation efficiency. Plasmid pNZ123 containing multicloning site and chloramphenicol resistance was employed to construct a cloning vector. The optimum electroporation conditions for the maximum transformation efficiency were a pulse strength of 12.5 kV cm(-1), a pulse number of 10, a pulse interval of 500 ms, and pNZ123 plasmid DNA concentration of 25 ng microl(-1). Under the optimum conditions the transformation efficiency of L. acidophilus ATCC 43121 was 1.84 +/- 0.13 x 10(4) (+/- standard error of measurements) CFU per mug of plasmid DNA. Other strains of L. acidophilus showed transformation efficiencies ranging from 1.38 +/- 0.02 x 10(4) to 9.32 +/- 0.54 x 10(4) under these conditions. A green fluorescent protein (GFP) was successfully expressed and detected by fluorescence microscopy when the pKU::slpA-GFP, pNZ123 containing GFP gene, was transformed in L. acidophilus ATCC 43121 under the optimum conditions. CONCLUSIONS: The results suggest that electrical parameters, antibiotic concentration, and host specificity play important roles to determine transformation efficiency of lactobacilli. The optimum conditions for the transformation of L. acidophilus ATCC 43121 may be applied to improve transformation efficiency of other lactobacilli. SIGNIFICANCE AND IMPACT OF THE STUDY: The optimized conditions for electrotransformation may provide a mean to improve the introduction of foreign DNA into L. acidophilus to be used as a vehicle for a heterologous protein expression.

Anti-Bacterial Agents↗

PubMed2004

Autologous peripheral blood stem cell transplantation with BCVAC conditioning in childhood acute myeloid leukemia.

Autologous peripheral blood stem cell transplantation (APBSCT) after intensifying conditioning is one of the post-remission therapeutic options in childhood acute myeloid leukemia (AML) patients without a matched family donor, but the optimal conditioning regimen has not been defined. This study was performed to evaluate the efficacy of a novel conditioning regimen without busulfan or total body irradiation. In total, 28 children with AML underwent APBSCT with BCVAC (BCNU, etoposide, cytosine arabinoside and cyclophosphamide) conditioning regimen during first remission. The event-free survival rate was 71.43% for all patients and the only cause of treatment failure was relapse. Eight male patients recurred at 1-11 months (median 5 months) after APBSCT. One patient remains alive with salvage therapy after relapse. With the exception of fever, mucositis and diarrhea, no serious complications occurred during APBSCT, including veno-occlusive disease (VOD), and there was no transplantation-related mortality. One patient developed secondary MDS after APBSCT but recovered hematologically on medication. APBSCT with BCVAC conditioning was found to be a safe and effective alternative option for patients with childhood AML in first remission, without a matched family donor.

Acute Disease↗

PubMed2003

Glanzmann's thrombasthenia due to a point mutation within intron 10 results in aberrant splicing of the beta3 gene.

Glanzmann's thrombasthenia (GT) is an hereditary bleeding disorder caused by a quantitative or qualitative defect in the integrin alphaIIbbeta3. We attempted to identify genetic defects responsible for a case of GT in Korea. The patient was a 6-year-old boy who had suffered from hemorrhage and purpura. The cDNAs of alphaIIb and beta3 were amplified by reverse transcription (RT)-PCR and were sequenced. RT-PCR of COS7 cells transfected with Exontrap vectors containing the beta3 genomic DNA fragments were performed to verify an aberrant splicing. Transient expression of alphaIIbbeta3 on transfected-COS7 cells was determined by flow cytometry, and the presence of alphaIIbbeta3 was confirmed by immunoprecipitation. We discovered an abnormality with the insertion of 38 bp between exon 10 and exon 11, including a stop codon, in beta3 cDNA. Sequence analysis of genomic DNA showed a point mutation, G-->T, at the position 29 107 of intron 10. RT-PCR analyses of COS7 cells transfected with Exontrap vector containing the mutant beta3 gene revealed that the point mutation at the position 29 107 of intron 10, G-->T, was responsible for an aberrant splicing in the beta3 gene. The transfection experiments and immunoprecipitation revealed the absence of alphaIIbbeta3 in the COS7 cells transfected with mutant gene. The mutation at the position 29 107 of intron 10, G-->T, in the beta3 genomic DNA was found to induce an aberrant splicing and to be responsible for GT in this patient.

Alternative Splicing↗

PubMed2003

Functionality and physico-chemical characteristics of bovine and caprine mozzarella cheeses during refrigerated storage.

Low moisture part-skim Mozzarella cheeses (MC) were manufactured using fresh bovine and caprine milk to study melting, physico-chemical, textural, and microstructural properties of the cheeses during 8 wk of refrigerated storage. Structural changes in cheese matrix were evaluated by scanning electron microscopy and by proteolytic patterns using nitrogen solubility, SDS-PAGE, and Gel-pro analyzer. Meltability of ripened cow and goat MC were not different when fat content of both milks were standardized, whereas bovine MC formed a significantly larger amount of free oil throughout the experiment. The results of the proteolytic patterns, texture attribute (cohesiveness), and microstructure revealed that bovine MC had a greater structural degradation of cheese matrix than caprine MC during the storage. Elevated protein degradation in bovine MC led to more intense brown color formation than the goat counterpart when the cheeses were baked. The melting characteristics showed high positive correlation (r = 0.51 to 0.80) with proteolysis, whereas it was negatively correlated with textural characteristics. Among textural attributes, cohesiveness was highly inversely correlated with melting characteristics (r = -0.69 to -0.88). High negative correlations were also observed between proteolytic parameters and textural attributes (r = -0.48 to -0.81).

Animals↗

PubMed2002

Right stereoisomers for sex pheromone components of the apple leafminer, Lyonetia prunifoliella, in Korea.

The sex pheromone of the American population of Lyonetia prunifoliella (Lepidoptera: Lyonetiidae) was reported to be composed of three components, 10,14-dimethyloctadec-1-ene (10me14me-1-ene-18Hy), 5,9-dimethyloctadecane (5me9me-18Hy), and 5,9-dimethylheptadecane (5me9me-17Hy). Studies with a Korean population showed that the 10S, 14S isomer of the major compound was the major electrophysiologically by active stereoisomer. The 5S,9S isomers of the minar constituents also elicited electrophysiological responses. In field trappings, among the three components, the racemic mixture of 10me14me-1-ene-18Hy attracted L. prunifoliella males strongly, and the binary or tertiary combinations with racemic mixtures of the other two components did not increase trap catches. Among the four stereoisomers of 10me14me-1-ene-18Hy, only the 10S,14S isomer attracted L. prunifoliella males, as suggested by the EAG test, and attraction to the other three isomers was not observed. All stereoisomers of each minor component, as well as their racemic components, did not seem to have any additional effect on male attraction in Korea.

Animals↗

PubMed2001

HLA-B*44 allele frequencies and haplotypic associations in Koreans.

We have investigated the frequencies of HLA-B*44 alleles and their haplotypic associations with HLA-A, -C, and -DRB1 loci in 450 healthy unrelated Koreans, including 213 parents from 107 families. All 79 samples (17.6%) typed as B44 by serology were analyzed for B*44 alleles using polymerase chain reaction (PCR) single-strand conformation polymorphism (SSCP) method. A total of three different B*44 alleles were detected: B*44031 (allele frequency 4.7%), B*44032 (3.1%), and B*4402 (1.3%). Three characteristic haplotypes revealing strong linkage disequilibrium were A*3303-Cw*1403-B*44031-DRB1*1302 (3.6%), A*3303-Cw*07-B*44032-DRB1*0701 (2.8%), and A*3201-Cw*05-B*4402-DRB1*0405 (0.4%). In addition, a strong association was observed for B*4402 with A*0301. The B*4403-bearing haplotypes of Koreans appear to be relatively common in Asian populations, whereas the B*4402-bearing haplotypes share some similarity to those of Caucasians. HLA-B44 alleles demonstrate a limited allelic diversity and comprise distinctive extended haplotypes in the Korean population. It is suggested that the frequencies of B44 subtype mismatches among ABDRB1-matched unrelated donor-recipient pairs would be low in this population.

Alleles↗

PubMed2001

The p38 mitogen-activated protein kinase pathway regulates interleukin-6 synthesis in response to tumor necrosis factor in osteoblasts.

The induction of interleukin-6 (IL-6), using a proinflammatory cytokine (tumor necrosis factor-alpha), was studied in a human osteoblast cell line (MG-63) in relation to p38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-kappaB transcription factor. When added to MG-63 cells, tumor necrosis factor-alpha (TNF-alpha) had a stimulatory effect on the production of IL-6, and this elevation was significantly reduced by SB203580, a specific p38 MAPK inhibitor. In addition, the stimulation of IL-6 release was also reduced by pyrrolidine dithiocarbamate (PDTC) or NF-kappaB SN50, which has been reported to be a potent NF-kappaB inhibitor. Both the NF-kappaB inhibitors in the presence of SB203580 had a more inhibitory effect on IL-6 release. In this study, TNF-alpha stimulated NF-kappaB binding affinity as well as p38 MAP kinase activation, leading to the release of IL-6. However, the specific inhibitor of p38 MAPK, SB203580, had no effect on TNF-alpha-induced NF-kappaB activation and both NF-kappaB inhibitors failed to reduce the p38 MAPK activation in the TNF-alpha-stimulated osteoblasts. In addition, inhibition of p38 MAPK partially, but significantly, impaired TNF-alpha-regulated release of osteocalcin, an important differentiation marker in osteoblasts. These results strongly suggest that both p38 MAPK and NF-kappaB are required in TNF-alpha-induced IL-6 synthesis and that these two TNF-alpha-activated pathways can be primarily dissociated. Furthermore, p38 MAPK may play a significant role in differentiation in MG-63 cells.

Antioxidants↗

PubMed2001

HLA-B*07 allele frequencies and haplotypic associations in Koreans.

We have investigated the frequencies of HLA-B*07 alleles and their haplotypic associations with HLA-A, -C and -DRB1 loci in 489 healthy unrelated Koreans, including 214 parents from 107 families. All of the 45 samples (9.2%) typed as B7 by serology were analyzed for B*07 alleles using polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) method. Two different B*07 alleles were detected: B*0702 (allele frequency 0.041) and B*0705 (0.005). Two characteristic haplotypes showing strong linkage disequilibrium in Koreans were A*2402-Cw*07-B*0702-DRB1*0101 (haplotype frequency 0.028) and A*2901-B*0705-DRB1*0803 (0.005). The characteristic haplotype A*2901-B*0705-DRB1*0803, found in 100% (5/5) of B*0705-positive individuals, has not been previously described in other ethnic groups. HLA-B7 alleles comprise distinctive extended haplotypes in the Korean population. The probability of HLA-B7 allele mismatches among ABDR-matched unrelated donor-recipient pairs is expected to be low in Koreans.

Alleles↗

PubMed2001

1,2-bis(2-Aminophenoxy)ethane-N,N,N',N'-tetraacetic acid induces caspase-mediated apoptosis and reactive oxygen species-mediated necrosis in cultured cortical neurons.

Sustained alteration in [Ca(2+)]i triggers neuronal death. We examined morphological and signaling events of Ca(2+)-deficiency-induced neuronal death. Cortical cell cultures exposed to 20 microM 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA-AM), an intracellular calcium chelator, underwent neuronal apoptosis within 12 h that was evident by shriveled cell bodies, aggregated and condensed nuclear chromatin, and disrupted nuclear membrane. Thereafter, surviving neurons revealed typical necrosis, accompanied by swelling of cell body and mitochondria, over 24 h. Both apoptosis and necrosis were prevented by inclusion of 1 microg/mL cycloheximide, a protein synthesis inhibitor. Treatment with BAPTA-AM induced translocation of Bax into mitochondria within 4 h and release of cytochrome c from mitochondria over 4-12 h. An active fragment of caspase-3, a downstream mediator of cytochrome c, was observed within 8 h and cleaved PHF-1-positive tau. Administration of zVAD-fmk, a broad inhibitor of caspases, or DEVD-amc, a selective inhibitor of caspase-3, selectively prevented the apoptosis component of BAPTA-AM neurotoxicity. In contrast, BAPTA-AM-induced necrosis was propagated through sequential production of superoxide, mitochondrial and cytoplasmic reactive oxygen species. Combined treatment with caspase inhibitors and antioxidants blocked BAPTA-AM neurotoxicity. The present study suggests that neurons deficient in [Ca(2+)]i undergo caspase-3-mediated apoptosis and reactive oxygen species (ROS)-mediated necrosis.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed2001

Hypoxia induces apoptosis by caspase activation accompanying cytochrome C release from mitochondria in MC3T3E1 osteoblasts. p38 MAPK is related in hypoxia-induced apoptosis.

The aim of this study is to elucidate the possible mechanism of apoptosis in response to hypoxia in MC3T3E1 osteoblasts. MC3T3E1 osteoblasts under hypoxic conditions (2% oxygen) resulted in apoptosis in a time-dependent manner estimated by DNA fragmentation assay and nuclear morphologystained with fluorescent dye, Hoechst 33258. Pretreatment with Z-VAD-FMK, a pan-caspase inhibitor, or Z-DEVD-CHO, a specific caspase-3 inhibitor, completely suppressed the DNA ladder in response to hypoxia. An increase in caspase-3-like protease (DEVDase) activity was observed during apoptosis, but no caspase- activity (YVADase) was detected. To confirm what caspases are involved in apoptosis, western blot analysis was performed using anti-caspase-3 or -6 antibody. The 10-kDa protein, corresponding to the active products of caspase-3 and the 10-kDA protein of the active protein of caspase-6 were generated in hypoxia-challenged cells in which processing of the full length form of caspase-3 and -6 was evident. With a time course similar to this caspase-3 and -6 activation was evident, hypoxic stress caused the cleavage of lamin A, typical of caspase-6 activity. In addition, the stress elicited the release of cytochrome c into the cytosol during apoptosis. Furthermore, we have observed that pre-treatment with SB203580, a selective p38 MAP kinase (p38 MAPK) inhibitor, attenuated the hypoxia-induced apoptosis. The addition of SB203580 suppressed caspase-3 and -6-like protease activity by hypoxia up to 50%. In contrast, PD98059 had no effect on the hypoxia-induced apoptosis. To confirm the involvement of MAP kinase, JNK/SAPK, ERK, or p38 kinase assay was performed. Although p38 MAPK was activated in response to hypoxic treatment, the other MAP kinase -JNK/SAPK or ERK- was not or modestly activated. These results suggest that p38 MAPK positively regulates hypoxia-induced apoptosis in MC3T3E1 osteoblasts.

3T3 Cells↗

PubMed2000

Intestinal first-pass effect of bumetanide in rats.

The intestinal first-pass effect of bumetanide was investigated after intravenous and intraportal infusion, and intragastric and intraduodenal instillation of the drug to rats. The AUC(0-->8 h) values of bumetanide after intragastric and intraduodenal instillation of the drug, 10 and 20 mg/kg, were significantly smaller than AUC values after intraportal administration, suggesting that the gastrointestinal first-pass effect of bumetanide was considerable in rats. However, the AUC(0-->8 h) values of bumetanide between intragastric and intraduodenal instillation were comparable, suggesting that the gastric first-pass effect of bumetanide was almost negligible in rats. The AUC(0-->8 h) values of bumetanide after intraduodenal instillation were significantly smaller than AUC values after intraportal infusion at 10 (89.8 vs 569 microg min per ml) and 20 (304 vs 1230 microg min per ml) mg/kg, indicating that the first-pass organ(s) of bumetanide was intestine. The F values were 15.8 and 24.7% after intraduodenal instillation of bumetanide, 10 and 20 mg/kg, respectively. Approximately 76.1 and 76.5% of intraduodenally instilled bumetanide disappeared (as a result of absorption and first-pass effect) after 10 and 20 mg/kg, respectively. Therefore, it could be concluded that approximately 60. 3 and 51.8% of the oral dose of bumetanide disappeared by intestinal first-pass effect at 10 and 20 mg/kg, respectively.

Animals↗

PubMed2000

Pharmacokinetics of a new proton pump inhibitor, YJA-20379-8, after intravenous and oral administration to spontaneously hypertensive rats and DOCA-salt-induced hypertensive rats.

The purpose of this study was to investigate the causes for the differences observed in the pharmacokinetics of YJA-20379-8 in 16-week-old spontaneously hypertensive rats (SHRs). To see if the hereditary characteristics of SHRs was the cause, 20 mg/kg of the drug was intravenously infused over 15 min and 50 mg/kg of the drug was orally administered to 6-week-old SHRs and 16-week-old SHRs and their age-matched control Kyoto-Wistar (KW) rats. Also to see if the hypertensive status itself was the cause, the same doses were administered to 16-week-old deoxycorticosterone acetate (DOCA) salt-induced hypertensive rats (DOCA-salt rats) and their age-matched control Sprague-Dawley rats. The areas under the plasma concentration-time curve from time zero to time infinity (for intravenous study) and to the last sampling time in plasma (for oral study) were significantly smaller after both intravenous and oral administration, and the total body clearances of the drug were significantly faster after intravenous administration to 6-week-old SHRs, 16-week-old SHRs, and 16-week-old DOCA-salt rats than those in their respective age-matched control rats. The above pharmacokinetic parameter changes in 16-week-old SHRs were due to both hereditary characteristic of SHRs and the hypertensive status itself.

Administration, Oral↗

PubMed2000

Molecular mechanism of staurosporine-induced apoptosis in osteoblasts.

Staurosporine, a microbial alkaloid, is a strong inhibitor of protein kinases. We induced apoptosis in murine osteoblast MC3T3E-1 cells by exposure to the staurosporine. Staurosporine transiently increased the phosphotransferase activity of c-Jun N-terminal kinase-1 (JNK1), which in turn may activate the transcriptional activity of activating protein-1 (AP-1). We then prepared extracts from staurosporine-treated MC3T3E-1 cells and monitored the cleavage of acetyl-YVAD-AMC and acetyl-DEVD-AMC, fluorogenic substrates of caspase-1-like and caspase-3-like proteases, respectively. Staurosporine caused a significant increase in the proteolytic activity of caspase-3-like proteases, but not in the activity of caspase-1-like proteases. Furthermore, staurosporine increased the transcriptional activity of nuclear factor- kappa B (NF- kappa B). These data suggest that staurosporine-induced apoptosis in osteoblasts may occur via activation of JNK1, caspase-3-like proteases, and transcriptional factors including AP-1 and NF- kappa B.

3T3 Cells↗

PubMed2000

HLA-A*02 allele frequencies and haplotypic associations in Koreans.

We have investigated the frequencies of HLA-A*02 alleles and their haplotypic associations with HLA-B and -DRB1 loci in 439 healthy unrelated Koreans, including 214 parents from 107 families. All of the 227 samples (51.7%) typed as A2 by serology were analyzed for A*02 alleles using polymerase chain reaction (PCR)-low ionic strength-single-strand conformation polymorphism (LIS-SSCP) method. A total of six different A*02 alleles were detected (A*02 allele frequency 29.6%): A*0201/9 (16.6%), *0203 (0.5%), *0206 (9.3%), *0207 (3.0%), and one each case of *0210 and *02 undetermined type. Two characteristic haplotypes showing the strongest linkage disequilibrium were A*0203-B38-DRB]*1502 and A*0207-B46-DRB1*0803. Besides these strong associations, significant two-locus associations (P<0.001) were observed for A*0201 with B61, DRB1*0901 and DRB1*1401, and for A*0206 with B48 and B61. HLA haplotypes carrying HLA-A2 showed a variable distribution of A*02 alleles, and all of the eight most common A2-B-DR haplotypes occurring at frequencies of > or =1% were variably associated with two different A*02 alleles. These results demonstrate that substantial heterogeneity is present in the distribution of HLA-A*02 alleles and related haplotypes in Koreans.

Alleles↗

PubMed2000

Evaluation by solid vascular casts of arterial geometric optimisation and the influence of ageing.

In the theoretical analysis of arterial networks the existence of geometric optimisation has long been suggested, although observational studies have not yet fully corroborated these theories. Since this could be due to experimental flaws, the aim of this study was to establish the validity of arterial geometric optimisation using a new experimental design and to assess the influence of ageing. Solid vascular casts of arterial mesenteric branching systems of 8-wk-old and adult dogs (beagles) were used to examine vascular diameters and branching angles, the latter in a manner that allowed optimisation of the line of view, thus minimising distortion errors due to a line of view not normal to the branching plane. Internal and external vessel diameters were found to be in accordance with the theoretical principle of minimum work (8-wk-old internal: r = 0.994; adult internal: r = 0.971; adult external: r = 0.985). Although branching angles were found to be in agreement with basic qualitative principles of arterial branching geometry, the measurements still showed a large amount of scatter and were generally smaller than expected on theoretical grounds, despite the newly designed measuring technique. These branching angles demonstrated small age-related differences. However, when biological cost was considered per bifurcation, surprisingly, guidance towards minimum lumen volume and pumping power with increase in age could clearly be demonstrated (P < 0.001). It is concluded that our findings support the existence of a degree of arterial geometric optimisation in favour of minimum lumen volume and pumping power, increasing with age. Future investigations should focus on the biofeedback mechanisms involved.

Aging↗

PubMed2000

Synergetic activation of p38 mitogen-activated protein kinase and caspase-3-like proteases for execution of calyculin A-induced apoptosis but not N-methyl-d-aspartate-induced necrosis in mouse cortical neurons.

We examined the possibility that p38 mitogen-activated protein kinase and caspase-3 would be activated for execution of apoptosis and excitotoxicity, the two major types of neuronal death underlying hypoxicischemic and neurodegenerative diseases. Mouse cortical cell cultures underwent widespread neuronal apoptosis 24 h following exposure to 10-30 nM calyculin A, a selective inhibitor of Ser/Thr phosphatase I and IIA. Activity of p38 was increased 2-4 h following exposure to 30 nM calyculin A. Addition of 3-10 microM PD169316, a selective p38 inhibitor, partially attenuated calyculin A neurotoxicity. Activity of caspase-3-like proteases was increased in cortical cell cultures exposed to 30 nM calyculin A for 8-16 h as shown by cleavage of DEVD-p-nitroanilide and phosphorylated tau. Proteolysis of tau was completely blocked by addition of 100 microM N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (z-VAD-fmk), a broad-spectrum inhibitor of caspases, but incompletely by 10 microM PD169316. Calyculin A neurotoxicity was partially sensitive to 100 microM z-VAD-fmk. Cotreatment with 10 microM PD169316 and 100 microM z-VAD-fmk showed additive neuroprotection against calyculin A. Neither PD169316 nor z-VAD-fmk showed a beneficial effect against excitotoxic neuronal necrosis induced by exposure to 20 microM NMDA. Thus, caspase-3-like proteases and p38 likely contribute to calyculin A-induced neuronal apoptosis but not NMDA-induced neuronal necrosis.

Amino Acid Chloromethyl Ketones↗