Blocking of acidosis-mediated apoptosis by a reduction of lactate dehydrogenase activity through antisense mRNA expression

Lactic acid produced from the cells is a potential cause of extra- and intracellular acidification. Due to scarce technical tools, lactic acid that leads to acidification could not be reduced and direct evidence of the relationship between metabolic lactate and apoptosis has not yet been elucidated. In this study, we designed a cellular pH regulation system in CHO cells by a reduction of lactate dehydrogenase (LDH) activity through LDH antisense mRNA expression. This inhibited lactate production and, therefore, acidification of the cytosol. Under HCO3(-)-buffered growth conditions, both the parent CHO cells and the engineered CHO cells maintained their extracellular pH and intracellular pH fairly well. However, upon acidification of the cytosol, only the parent CHO cells underwent apoptosis under HCO3(-)-free conditions. In fact, we observed a number of apoptosis-related events only in control cells, including mitochondrial dysfunction, cytochrome c release, and an increase in caspase-3 enzymatic activity.

Polymorphism of the angiotensin-converting enzyme gene in patients with cerebral infarction in Koreans

The relationship between cerebrovascular disease and an insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene is still being debated. The frequency of the DD genotype of the ACE gene was significantly higher in subjects with than those without cerebral infarction in Japan. The aim of the present study was to assess the relationship between ACE gene polymorphism and the development of cerebral infarction in a population from Korea. We examined its possible role as a risk factor in patients with cerebral infarction. The association between ACE gene polymorphism and cerebral infarction was examined in 106 patients with cerebral infarction and 498 controls without cerebral infarction. Frequencies of the genotypes and alleles of the ACE gene were investigated. The ACE genotype was analyzed by the polymerase chain reaction (PCR). The frequency of D allele was 37.7% in patients and 39.1% in controls (chi2 = 0.128, p = 0.720). The frequencies of the genotypes of the ACE gene were II: 39.6%, ID: 45.3%, and DD: 15.1% in patients, and II: 37.1%, ID: 47.6%, and DD: 15.3% in controls (chi2 = 0.127, p = 0.721). There was no significant difference in the frequency of the DD genotype of the ACE gene, and we did not find any association between ACE polymorphism and cerebral infarction. These results indicate that ACE polymorphism is not a risk factor for the development of cerebral infarction in a Korean population.

An effective technique for open reduction of mandibular angle fractures using new reduction forceps: technical innovations

We demonstrate a new technique that is useful for precompressing and holding mandibular angle fractures by means of new reduction forceps. The forceps were designed for application in the mandibular angle area via a transoral approach.

Increased angiogenesis and Fas-ligand expression are independent processes in acute myeloid leukemia

We evaluated the clinical significance of tumor angiogenesis and Fas-ligand (FasL) expression using parameters including the microvessel count (MVC), vascular endothelial growth factor (VEGF) level, and FasL expression in patients with acute myeloid leukemia (AML). Paraffin-embedded bone marrow (BM) sections from 43 AML patients at diagnosis, 20 patients after subsequent induction therapy, and 18 controls with non-invasive lymphoma were stained immunohistochemically for von Willebrand factor (vWF) and FasL. VEGF in BM mononuclear cells from 32 AML patients at diagnosis and 10 controls, including bone marrow transplantation donors, was assayed by an ELISA method. We found that the mean MVC, VEGF level, and FasL expression in AML patients at diagnosis were significantly higher than those of controls, with a significant correlation between the MVC and VEGF levels (r=0.43). However, there were no correlations between FasL expression and MVC or VEGF level. The mean MVC and FasL expression after induction therapy were lower than those evaluated at diagnosis, but were higher than those of controls. There was a correlation between the MVC and percentage of BM blasts (r=0.479), but no correlation between the MVC, VEGF level, or FasL expression and other hematologic or clinical variables. Our findings provide evidence of increased angiogenesis and tumor immune escape in AML, and both angiogenesis and tumor immune escape are independent processes in AML.

P16INK4a protein expression is associated with poor survival of the breast cancer patients after CMF chemotherapy

Immunohistochemical assay for p16 protein expession was performed in 192 breast carcinoma patients treated with adjuvant chemotherapy. p16 expression was observed in 78 cases (40.6%). The frequency of p16 expression significantly decreased in moderately differentiated (histologic grade II) cancers, 20 (19.6%) of 102. In poorly differentiated cancers (histologic grade III), p16 expression was not observed in all 16 cases. p16 expression was significantly associated with histologic grade of the breast carcinomas (p < 0.001). The proliferative index (PI: S + G2/M) of individual tumors was measured by DNA flow cytometry. In 114 tumors with PI less than 20%, p16 expression was observed in 59 tumors (49.1%). In the tumors with PI equal or more than 20%, p16 expression was observed in 22 (28.2%) of 78 cases. p16 expression was significantly decreased in the tumor with higher PI (p =0.003). For the other clinicopathologic variables, no significant association was found with p16 expression status. Immunohistochemical assay for p53 protein expression was performed on the same breast carcinomas. There was no significant association between p16 and p53 expression in breast carcinomas. During median follow-up period of 52 months (range: 40-72 months), 46 patients (25.8%) had recurrent disease and 32 patients (18.91%) died of recurrent disease. p16 expression was observed in 20 (43.5%) of 46 patients with recurrent disease, while its expression was observed in 58 patients (39.7%) of 146 patients who were free of recurrence during the study period. p16 expression had no significant impact on predicting recurrence of breast carcinoma. Fourteen patients (12.2%) of 114 patients whose tumors did not show p16 expression died of recurrent breast carcinoma, whereas 18 patients (23.1%) of 78 patients with p16 expressing tumor died during the follow-up period. There was a significant difference of patient survival according to p16 expression status (p = 0.039). These results indicate that p16 expression is useful in predicting response to chemotherapy in breast cancer patients. p16 protein seems to have a role in tumor growth and differentiation of the breast carcinoma.

Ambulatory treatment of multidrug-resistant pulmonary tuberculosis patients at a chest clinic

SETTING

Retrospective cohort analysis of multidrug-resistant tuberculosis (MDR-TB) patients treated at a Korean National Tuberculosis Association out-patient chest clinic.

OBJECTIVE

To evaluate treatment outcomes and contributing factors.

DESIGN

A review of clinical records of 1011 pulmonary MDR-TB patients retreated with individualised regimens selected on the basis of previous chemotherapy and drug susceptibility testing from 1988 to 1996.

RESULTS

The patients (mean age 38.6 years) had resistant organisms to an average of 3.7 drugs and were retreated with an average of 4.2 drugs which they had previously not taken and to which they were susceptible. Treatment outcomes were as follows: 487 cases (48.2%) cured, 82 (8.1%) failed, 394 (39.0%) defaulted, 45 (4.5%) transferred out, and three (0.3%) died. The treatment efficacy among those who completed chemotherapy was 85.6%. In a multivariate analysis favourable response was significantly associated with a greater number of newly prescribed drugs in the regimen to which they were susceptible (odds ratio [OR] 3.6; 95% confidence interval [CI] 1.3-9.5), younger age (OR 2.0; 95%CI 1.1-3.9), and a lower number of drugs to which they were resistant (OR 1.8; 95%CI 1.1-3.1). The case fatality rate, including the follow-up period, was 1.7% (17 cases).

CONCLUSION

The cure rate of MDR-TB patients treated at an out-patient clinic was 48.2% due to a high defaulter rate (39.0%). However, 85.6% of those who completed treatment were cured.

A cytotoxic secocycloartenoid from Abies koreana

Two triterpenoids, 24-methylene-3,4-seco-cycloart-4(28)-en-3-oic acid (1) and 3-oxo-9beta-lanosta-7,22Z,24-trien-26,23-olide (6) were isolated from Abies koreana, together with beta-sitosterol (2), maltol (3), beta-sitosterol-O-beta-D-glucoside (4), and hexacosylferulate (5). The structures of the compounds were established based on the spectroscopic data. The cytotoxic activities of triterpenoids have been evaluated using the sulforhodamine B (SRB) method. Compound 1 showed moderate cytotoxicities against human lung carcinoma (A549), ovarian carcinoma (SK-OV-3), malignant melanoma (SK-MEL-2), and colon carcinoma (HCT-15) cell lines.

Association between Helicobacter pylori infection and the risk of gastric cancer in the Korean population: prospective case-controlled study

BACKGROUND

Gastric cancer is still the most common malignant tumor in Koreans. Although many reports have supported the association of Helicobacter pylori infection and the development of gastric cancer, few studies have been adjusted by variable factors such as age. sex, education, and economic status. Furthermore, most results from areas with a high incidence of gastric cancer, such as China and Korea, have failed to document any relationship between H. pylori infection and gastric cancer. We conducted a prospective case-controlled study, with controls matched for and adjusted by age, sex, education, and economic status, to evaluate the causal relationship between H. pylori infection and gastric cancer in Korean people.

METHODS

From March 1997 to October 1998, 136 consecutive patients with gastric cancer, diagnosed by endoscopic histology, and 136 age- and sex-matched control subjects, confirmed to be free of gastric cancer by endoscopy during the same period, were enrolled in the study. The presence of H. pylori infection was determined by enzyme immunoassay (EIA) serology test.

RESULTS

Seventy-two of the 136 gastric cancer patients (53%) were positive for H. pylori infection and 54 of the 136 control subjects (40%) were positive for H. pylori infection. The odds ratio (OR), adjusted by variable risk factors, such as age, sex, education, and economic status, for gastric cancer in H. pylori-infected patients was 1.82 (95% confidence internal [CI], 1.10-3.00; P = 0.019). The age- and sex-matched OR by conditional logistic regression was 1.6 (95% CI., 1.01-2.53; P = 0.043).

CONCLUSIONS

H. pylori infection may be one of the important risk factors for the development of gastric cancer in Korea, an area of high prevalence of H. pylori infection and a high incidence of gastric cancer.

Chronic hepatitis: in vivo proton MR spectroscopic evaluation of the liver and correlation with histopathologic findings

PURPOSE

To correlate the in vivo hydrogen 1 ((1)H) magnetic resonance (MR) spectroscopic features of the chronic hepatitis-involved liver with the histopathologic stages of fibrosis.

MATERIALS AND METHODS

Seventy-five patients with chronic hepatitis were examined with (1)H MR spectroscopy, which was performed in the right hepatic lobe. The peak areas of glutamine and glutamate complex (Glx), phosphomonoesters (PME), glycogen and glucose complex (Glyu), and lipid were measured on the liver spectra. The histopathologic features were correlated with the in vivo (1)H MR spectroscopic findings at each stage of chronic hepatitis. Fifteen healthy volunteers also were included as a control group.

RESULTS

(1)H MR spectroscopy depicted Glx, PME, Glyu, and lipid in all livers. In the normal livers, the calculated mean (+/- SD) relative metabolite-to-lipid ratios of Glx, PME, and Glyu were 0.14 +/- 0.04, 0.03 +/- 0.01, and 0.21 +/- 0.04, respectively. The mean value of each metabolite-to-lipid ratio was significantly different between all stages of chronic hepatitis, and with the exception of the mean ratio at the interval between stages 0 and 1 (P > .05), the mean value increased significantly with increasing stage (P < .05). A pronounced peak was demonstrated at 3.9-4.1 ppm at (1)H MR spectroscopy of all stages of chronic hepatitis except stage 0.

CONCLUSION

The increased Glx, PME, and Glyu levels relative to the lipid content with chronic hepatitis indicated the severity of fibrosis and thus were concordant with the histopathologic stages. In vivo (1)H MR spectroscopy might be a substitute for liver biopsy in the diagnosis and staging of chronic hepatitis.

Sympathetic sprouting in sensory ganglia depends on the number of injured neurons

We examined whether the extent of sympathetic sprouting in the dorsal root ganglion was a function of the number of injured nerve fibers. We compared two groups of rats. One group was subjected to unilateral superior and inferior caudal trunk transections at the level between the S1 and S2 spinal nerves (S-I group) and the other group was subjected to unilateral superior caudal trunk transection at the same level (S group). Immunohistochemical staining with tyrosine hydroxylase (TH) antibody of the S1 DRG revealed that the degree of TH-immunoreactive fibers was more extensive in the S-I group than in the S group. However, there was no difference in the severity of neuropathic pain behaviors between the two groups. These results suggest that the extent of sympathetic sprouting in the DRG following peripheral nerve injury is proportionally related to the amount of injured nerve fibers, but not related to the degree of neuropathic pain behaviors.

Ether fraction of methanol extracts of Gastrodia elata, a traditional medicinal herb, protects against kainic acid-induced neuronal damage in the mouse hippocampus

Gastrodia elata (GE) has been used traditionally for the treatment of convulsive diseases such as epilepsy in oriental countries including South Korea and still occupies an important place in traditional medicine in Asia. We studied the anticonvulsive effect and protective effect of the ether fraction of methanol extracts (EFME) of GE against hippocampal neuronal damage after kainic acid administration in mice. Mice were treated with the EFME of GE (200 or 500 mg/kg per day, p.o.) for 14 days before kainic acid injection (45 mg/kg, i.p.). The EFME of GE (at the dose of 500 mg/kg) delayed the onset time of neurobehavioral change (P<0.01) and reduced the severity of convulsions (P<0.05) and hippocampal neuronal damage in the CA1 (P<0.01) and CA3 (P<0.05) regions. Our results show that The EFME of GE has anticonvulsive effect and putative neuroprotective effect against excitotoxicity induced by kainic acid.

Chiral separation of 9-fluorenylmethyl chloroformate- and dansyl chloride-derivatized D,L-serine by gamma-cyclodextrin-bonded high-performance liquid chromatography

When acetate buffer was used in chiral separation of D,L-serine derivatives using a gamma-cyclodextrin (CD) column, both retention factor and resolution were high below the pKa of acetic acid and decreased sharply as the pH approached the pKa. A similar result was obtained by increasing the buffer concentration at a fixed pH. These observations suggest that hydrogen bonding interaction between the carboxylate group of the amino acid and the secondary hydroxyl groups at the CD rim plays an important role in chiral separation and is disrupted by the buffer anion.

Association between maternal diabetes mellitus and newborn oral cleft

Diabetes mellitus has been implicated in several studies as a possible etiological factor of various congenital anomalies. Oral clefts are common congenital malformations that may severely affect the quality of life. The authors conducted a population-based case-control study using the 1996 National Center for Health Statistics United States Natality database to investigate whether maternal diabetes mellitus is a risk factor (p < 0.05) for having a newborn with an oral cleft. The patients consisted of 2,207 live births with cleft lip/palate, and the control subjects were 4,414 randomly selected live births, excluding those with other congenital defects. After adjusting for potential confounding variables, diabetic mothers were found to be 1.352 times (95% confidence interval, 1.004-1.821; p < 0.05) more likely than nondiabetic mothers to have a newborn with cleft lip/palate. In counseling expectant mothers, early glycemic control may be an important factor in decreasing the incidence of this congenital anomaly.

Encephalitis associated with motor polyneuropathy

We describe three patients with acute encephalitis and motor-dominant polyneuropathy. All three patients were in their middle age and presented with features of encephalopathy with flu like illness. Cerebrospinal fluid (CSF) studies showed lymphocytic pleocytosis with increased protein. Brain magnetic resonance imagings (MRIs) showed symmetric high signal intensities in bilateral mesial temporal lobes and bilateral thalami in all patients. All three patients became quadriplegic and areflexic within two hospital days (HDs) and electrophysiologic studies revealed motor polyneuropathy. Viral or atypical bacterial infection was suspected, but no causative agent could be found. One patient expired on the twentieth hospital day, and the other two patients showed no or little improvement. To our knowledge, this combination of acute encephalitis with motor polyneuropathy has not been reported.

The kinetics of circulating cytokines including IL-6, TNF-alpha, IL-8 and IL-10 following allogeneic hematopoietic stem cell transplantation

Pro-inflammatory (IL-6, TNFalpha and IL-8) and anti-inflammatory (IL-10) cytokines were determined in weekly samples from 52 patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT). IL-6 increased immediately after transplant peaking at week +3, but IL-8 concentrations were elevated only during week +1. After a slight decrease in week +1, TNF-alpha significantly increased from week +2 and peaked at week +3, whereas, IL-10 values started to rise in week +2 and peaked during week +4. IL-6 and TNF-alpha were positively correlated from week +2 to week +4, and IL-6 levels at week +1 were related with fever and severe stomatitis. Serum levels of IL-6 at week +1 and IL-10 at week +4 were significantly higher in patients with early transplant-related complications, such as fever, severe stomatitis or acute GVHD > or = overall grade II than in those without the complications. We conclude that a high serum IL-6 level at week +1 may be an early predictor of transplant-related complications and that it seems to trigger pro- and anti-inflammatory cytokine release. Kinetic patterns of IL-6 and IL-10 were more exaggerated in those with complications after HSCT.

Local expression and distribution of a storage protein in the ovary of Hyphantria cunea

Storage protein-1 (HcSP-1) is a major storage protein found in the hemolymph and fat body of Hyphantria cunea. HcSP-1 has a high methionine (6.0%) and low aromatic amino acid content (8.5%) (Cheon et al., 1998). In this study, the accumulation and expression of HcSP-1 in ovary was investigated using biochemical and immunocytochemical methods. HcSP-1 was detected in the ovaries in 6-day-old pupae and accumulated toward the end of pupal life, when HcSP-1 transcripts were detectable by Northern blot analysis and RT-PCR. In situ hybridization showed that the HcSP-1 mRNA was located in the nurse cells and follicular epithelial cells, but not in the oocyte. Though most of the HcSP-1 that is incorporated in the yolk bodies of the oocyte is probably sequestered from the surrounding hemolymph, HcSP-1 is an important yolk protein contributing to early yolk body formation before the development of patency by the follicular epithelium.

Assessment of left atrial appendage filling pattern by using intravenous administration of microbubbles: comparison between mitral stenosis and mitral regurgitation

Mitral stenosis (MS) and mitral regurgitation (MR) are the most frequent conditions that cause a dilation and dysfunction of the left atrial appendage (LAA). Despite similarly dilated LAA in patients with MS and MR, the incidence of LAA thrombi and the risk of thromboembolism is different between these patients. The purpose of this study was to characterize the filling pattern of LAA by using intravenous administration of perfluorocarbon-exposed dextrose albumin (PESDA) during transesophageal echocardiographic examination in patients with MS and MR. Twenty-four patients with moderate to severe MS, 12 patients with severe MR, and a control group including 30 patients with conditions other than mitral valve disease underwent transesophageal echocardiographic examination with an intravenous bolus injection of PESDA. LAA emptying and filling velocities and maximal and minimal areas of LAA and LAA ejection fraction were measured. Digital gray-scale intensity (GSI) of the left atrial (LA) and LAA cavity after PESDA injection was measured by off-line analysis. Compared with control patients, patients with MS or MR had larger maximal and minimal areas of LAA and reduced LAA ejection fraction. LAA peak emptying flow velocity was significantly lower in patients with MS compared with those of MR or control patients. LAA peak filling velocity was significantly lower in patients with MS compared with that of control patients. However, there was no significant difference of LAA peak filling velocity between the patients with MS and MR. There was no significant difference of GSI ratio of LAA and LA between patients with MR and control patients; however, GSI ratio of LAA and LA was significantly lower in patients with MS compared with that of MR. The incidence of LAA spontaneous echo contrast and LAA thrombi in patients with MS was significantly higher than that of the patients with MR and control subjects (P <.005). Despite similarly dilated LAA area and depressed contractile function of LAA in patients with MS and MR compared with control patients, profoundly impaired LAA filling with resultant flow stasis was demonstrated by contrast echocardiography in patients with MS. These findings may explain the higher incidence of LAA spontaneous echo contrast and thrombus in patients with MS.

Molecular cloning and characterization of a gene encoding a 13.1 kDa antigenic protein of Naegleria fowleri

An antigen-related gene was cloned from a cDNA expression library of Naegleria fowleri by immunoscreening with sera obtained from mice that were either immunized with an amoebic lysate or infected with trophozoites. The coding nucleotide sequence of the cloned gene consisted of 357 bases that were translated into 119 amino acids. This gene was designated as nfa1. The predicted amino acid sequence of Nfa1 protein has two potential glycosylation and three potential phosphorylation sites, and its predicted secondary structure consists of four helices and three corners. The deduced amino acid sequence of Nfa1 protein shares 43% identity with the myohemerythrin (myoHr) protein from a marine annelid, Nereis diversicolor, including 100% identity in conserved regions and iron-binding residues. A phylogenetic tree constructed from amino acid sequences placed the N. fowleri Nfa1 protein outside of a cluster of myoHr proteins from eight invertebrates. A purified recombinant protein that migrated as a 13.1 kDa species in SDS-PAGE was produced. This recombinant protein exhibited a strong immunoreactivity with infected, immune, and anti-Nfal sera. In addition, an anti-Nfa1 serum reacted with an amoeba lysate in immunoblotting analysis. The present nfal gene encoding the myoHr-like protein is the first myoHr gene cloned from protozoa, and the Nfal antigen may be useful in diagnostic studies

Demonstration of Epstein-Barr virus in odontogenic and nonodontogenic tumors by the polymerase chain reaction (PCR)

BACKGROUND

Although considerable insight has been gamed into Epstein-Barr virus (EBV) as an important etiologic factor in various tumors, virtually little is known about the relationship between EBV genes and oral tumors.

METHOD

Thirty-two cases of nonodontogenic tumor (16 squamous cell carcinomas, 11 salivary gland tumors, 1 malignant lymphoma, 1 spindle cell sarcoma, 1 osteogenic sarcoma, 1 malignant fibrous histiocytoma and 1 verrucous carcinoma), 17 cases of odontogenic tumor (17 ameloblastomas, the most important and common type of odontogenic tumor) and 12 cases of normal oral tissue (8 normal gingival tissues and other oral mucosa) were examined for the presence of EBV-DNA, with primers specific for the BamW, BNRF1, BMLF1, BamC, IR3, BMRF1, EBNA-2A BamhY, and EBNA-2B BamhY region of the EBV genome by the polymerase chain reaction (PCR).

RESULTS

Fifty-three percent (17/32) of nonodontogenic tumors, forty-eight percent (8/17) of ameloblastomas, and ninety-two percent (11/12) of normal oral tissues were positive for EBV-DNA. Of the EBV-DNA, BMLF1 demonstrated the strongest reactivity in the nonodontogenic tumors, and BamC demonstrated the strongest reactivity in the ameloblastomas and normal oral mucosae.

CONCLUSIONS

Taken into account with the expression of different EBV genes in odontogenic and nonodontogenic tumors, these findings suggest that even though odontogenic tumors and nonodontogenic tumors are relatively unique, the appearance of different EBV genes seems to suggest the complicated roles that the EBV genes play.

Intradural anastomoses between the accessory nerve and the posterior roots of cervical nerves: their clinical significance

This study was performed to identify the anastomoses between the accessory nerve and the posterior roots of cervical nerves below the level of C1 segment, and to evaluate their clinical significance. One hundred spinal cord sides of Koreans were studied under the surgical microscope. In order to trace the posterior root of a cervical nerve after anastomosis with the accessory nerve, or the bridging fibers between the accessory nerve and the cervical posterior roots, the accessory nerves with the posterior roots and the bridging fibers were stained with osmium tetroxide. The anastomosis was classified into five types, according to whether the accessory nerve and the cervical posterior root crossed each other, and also according to the site of the bridging fiber between them. The bridging fibers in the most common type of anastomoses were observed to connect the posterior roots of a cervical nerve with the spinal rootlet of the accessory nerve. The possibility that the motor fibers of accessory nerve from the spinal cord may innervate the trapezius muscle through the cervical nerve, was discussed.

Rac1 regulates heat shock responses by reorganization of vimentin filaments: identification using MALDI-TOF MS

Rac1 has been implicated in a wide variety of biological processes, including actin remodeling and various signaling cascades. Here we have examined whether Rac1 might be involved in heat shock-induced cell signaling. We found that Rat2 stable cells expressing a dominant negative Rac1 mutant, RacN17 (Rat2-RacN17), were significantly more tolerant to heat shock than control Rat2 cells, and simultaneously inhibited the activation of SAPK/JNK by heat shock compared to control Rat2 cells. However, no discernible effect was observed in typical heat shock responses including total protein synthesis and heat shock protein synthesis. To identify the proteins involved in this difference, we separated the proteins of both Rat2 and Rat2-RacN17 cell lines after heat shock using two-dimensional gel electrophoresis and identified the differentially expressed proteins by matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) after in-gel trypsin digestion. Differentially expressed proteins between two cell lines were identified as vimentin. Rat2-RacN17 cells showed significant changes in vimentin as well as marked changes in vimentin reorganization by heat shock. The vimentin changes were identified as N-terminal head domain cleavage. These results suggest that Rac1 plays a pivotal role in the heat shock-induced signaling cascade by modifying intermediate vimentin filaments.