Tone perception in Cantonese and Mandarin: a cross-linguistic comparison

This study investigated the effects of linguistic experience on tone perception. Both Cantonese (in Experiment 1) and Mandarin (in Experiment 2) tones, including both lexical and nonlexical tones, were presented to three groups of subjects: Cantonese, Mandarin, and English native speakers. Subjects were asked to determine whether two auditorily presented tones were the same or different. The interval between the presentation of the two tones, and the level of interference during this interval, were manipulated. Native speakers did better at discriminating tones from their own languages than the other two groups of subjects, for both lexical and nonlexical tones. Subjects did worst when they were required to count backward during the interstimulus interval. Cantonese speakers were better than both Mandarin and English speakers at discriminating Cantonese tones, and there was no difference between Mandarin and English speakers, except in one condition. Mandarin speakers did better than both Cantonese and English speakers, and Cantonese speakers did better than English speakers, at discriminating Mandarin tones. Results are discussed in terms of the effects of language background, differences between Cantonese and Mandarin tones, and the nature of encoding in short-term memory.

Crosslinking characteristics of an epoxy-fixed porcine tendon: effects of pH, temperature, and fixative concentration

Injury to the anterior cruciate ligament (ACL) often results in functional instability within the knee joint and may induce a severe articular deterioration. Clinically, these patients may require an ACL reconstruction. In an attempt to develop an improved ligament prosthesis, a prototype xenograft--an epoxy-fixed porcine Achilles tendon--was developed. The study was intended to investigate the crosslinking characteristics of the epoxy-fixed porcine tendons fixed at different pHs (4.0, 7.4, 9.0, and 10.5), temperatures (4, 25, and 37 degrees C), and fixative concentrations (1, 2, or 4%). Samples of each group were taken out at various elapsed fixation periods. The crosslinking characteristics-fixation index, denaturation temperature, and moisture content-of each sample were determined. Additionally, the stiffness of the epoxy-fixed tendons under various fixation conditions was qualitatively compared. In the study it was noted that the color of porcine Achilles tendons remained natural after epoxy fixation. With increasing pH, temperature, or fixative concentration, the fixation indices and denaturation temperatures of the epoxy-fixed tendons increased. However, the fixed porcine tendons tended to be stiffer at a higher pH, temperature, or fixative concentration. The moisture contents of the epoxy-fixed tendons were relatively lower than the fresh ones, while they were approximately the same at different pHs, temperatures, and fixative concentrations. The implications of these findings for the epoxy-fixed porcine tendons in ACL reconstruction require further investigation.

Protein kinase C-mediated functional regulation of dopamine transporter is not achieved by direct phosphorylation of the dopamine transporter protein

Dopaminergic neurotransmission is terminated by the action of the presynaptic dopamine transporter (DAT). It mediates Na(+)/Cl(-) -dependent re-uptake of extracellular dopamine (DA) into the cell, and is regarded as a major regulatory mechanism for synaptic transmission. Previous works have documented that protein kinase C (PKC) activator or inhibitor alters DA uptake by DAT, suggesting that PKC phosphorylation plays an important regulatory mechanism in DAT function. Based on the existence of consensus amino acid sequences for PKC phosphorylation, it has been postulated that PKC regulation of DAT is mediated by the direct phosphorylation of DAT protein. In this study, we try to discover whether the functional regulation of DAT by PKC is due to direct phosphorylation of DAT. The PKC null mutant hDAT, where all putative PKC phosphorylation sites are eliminated, has been constructed by the replacement of serine/threonine residues with glycines. The mutation itself showed no effect on the functional activities of DAT. The DA uptake activity of PKC null mutant was equivalent to those of wild-type hDAT (80-110% of wild-type). Phorbol ester activation of PKC inhibited DA uptake of wild-type hDAT by 35%, and staurosphorine blocked the effect of phorbol ester on DA uptake. The same phenomena was observed in PKC null mutant DAT, although no significant phosphorylation was observed by PKC activation. Confocal microscopic analysis using EGFP-fused DAT revealed that the activation of PKC by phorbol ester elicited fluorescent DAT to be internalized into the intracellular space both in wild-type and PKC null mutant DAT in a similar way. These results suggest that PKC-mediated regulation of DAT function is achieved in an indirect manner, such as phosphorylation of a mediator protein or activation of a clathrin-mediated pathway.

Effect of cytoplasmic lipid content on in vitro developmental efficiency of bovine IVP embryos

The objective was to evaluate the effect of cytoplasmic lipid content on the embryonic developmental efficiency of bovine in vitro embryo production (IVP) embryos. Ovaries from Korean native cows (Bos taurus coreanae) were collected from a local abattoir, and cumulus-oocyte complexes (COCs) were recovered from follicles 2 to 8mm in diameter. The oocytes were divided into three groups, dependent on their cytoplasm color: pale color (PC), brown color (BC), and dark color (DC). The COCs were fertilized using frozen-thawed semen from a single Hanwoo bull. Based on measurement of the cytoplasmic color intensity of oocytes after 22h of in vitro maturation (IVM), the DC group had lower (P<0.05) color intensity than that in the BC and PC groups (56.3+/-2.7, 93.3+/-5.1, and 123.9+/-12.0, respectively). Based on MitoTracker Green FM staining, the number of mitochondria in the DC (170.1+/-31.2) group was significantly higher than that in the BC (137.5+/-30.8) and PC (105.5+/-25.3) groups. The cleavage rate in the DC (81.5%) group was also higher than that in the PC (50.4%) group (P<0.05), as was the development rate to blastocyst stage (18.9% vs. 9.8%). Finally, cell numbers of blastocysts in the DC (150.8+/-28.0) group were higher (P<0.05) than that in the BC (107.6+/-17.8) and PC (80.5+/-12.3) groups. In conclusion, cytoplasm color was a useful selection parameter for abattoir-derived oocytes destined for IVP.

Characterization of GAR-2, a novel G protein-linked acetylcholine receptor from Caenorhabditis elegans

We have previously identified two G protein-linked acetylcholine receptors (GARs), GAR-1 and GAR-3, in the nematode Caenorhabditis elegans. Whereas GAR-3 is a homologue of muscarinic acetylcholine receptors (mAChRs), GAR-1 is similar to but pharmacologically distinct from mAChRs. In the current work we isolated a new type of GAR using C. elegans genome sequence information. This receptor, named GAR-2, consists of 614 amino acid residues and has seven putative transmembrane domains. Database searches indicate that GAR-2 is most similar to GAR-1 and closely related to GAR-3/mAChRs. The overall amino acid sequence identities to GAR-1 and GAR-3 are approximately 32 and approximately 23%, respectively. When GAR-2 was coexpressed with the G protein-activated inwardly rectifying K(+) (GIRK1) channel in Xenopus oocytes, acetylcholine was able to evoke the GIRK current in a dose-dependent fashion. Oxotremorine, a classical muscarinic agonist, had little effect on the receptor, indicating that GAR-2 is pharmacologically different from mAChRs but rather similar to GAR-1. GAR-2 differs from GAR-1, however, in that it showed virtually no response to muscarinic antagonists such as atropine, scopolamine, and pirenzepine. Expression studies using green fluorescent protein reporter gene fusion revealed that GAR-2 is expressed in a subset of C. elegans neurons, distinct from those expressing GAR-1. Together with our previous reports, this study demonstrates that diverse types of GARs are present in C. elegans.

A comparative study on the short-term clinicopathologic outcomes of laparoscopic surgery versus conventional open surgery for transverse colon cancer

BACKGROUND

The long-term oncologic stability of laparoscopic surgery for colon cancer was established, and laparoscopic surgery was accepted as an alternative to conventional open surgery for colon cancer. However, transverse colon cancer was excluded from the majority of the previous prospective studies. As a result, debate on laparoscopic surgery for transverse colon cancer continues. This study aimed to compare the clinicopathologic outcome of laparoscopic surgery with that of conventional open surgery for transverse colon cancer.

METHODS

From August 2004 to December 2007, 106 cases of transverse colon cancer were managed by resection at our institution, and 89 of these cases were included in this study. Age, sex, body mass index (BMI), operation time, blood loss, time to first flatus, time to start of diet, hospital stay, complications, tumor size, distal resection margin, proximal resection margin, and number of nodes harvested were compared between the two groups.

RESULTS

No significant differences were found between the laparoscopic and conventional groups in terms of age, sex, BMI, operation time, or hospital stay. The mean blood loss during the operations was significantly less in the laparoscopic group (113.8 +/- 128.9 ml) than in the conventional group (278.8 +/- 268.7 ml; p < 0.05). Moreover, the time to the first flatus was shorter (2.8 +/- 0.9 days vs. 4.4 +/- 2.0 days; p < 0.00) and the diet was started earlier (3.9 +/- 1.7 days vs. 5.4 +/- 1.9 days; p < 0.00) in the laparoscopic group. No intergroup differences in tumor size, proximal resection margin, or number of lymph nodes were observed. The mean distal resection margin was longer in the laparoscopic group (12.5 +/- 4.1 cm vs. 9.2 +/- 6.2 cm; p < 0.05).

CONCLUSION

Laparoscopic and conventional open surgeries were found to have similar clinical outcomes in transverse colon cancer, and the oncologic quality of laparoscopic surgery was found to be acceptable compared with conventional open surgery.

Treatment of chronic hepatitis B with lamivudine in renal transplant recipients

BACKGROUND

Lamivudine is a potent inhibitor of hepatitis B virus replication. Little has been reported about the efficacy and safety of lamivudine in the treatment of chronic hepatitis B in the setting of renal transplantation.

METHODS

Two patients were treated for chronic hepatitis B with lamivudine and subsequently underwent renal transplantation. Four other patients were treated with lamivudine for reactivation of hepatitis B after renal transplantation. Chronic hepatitis B was proven histologically in all the patients. The doses of lamivudine ranged from 100 to 150 mg/day. Hepatic enzyme and viral markers were monitored.

RESULTS

Lamivudine was well tolerated for a median duration of 8 months (range, 4-14 months) without significant side effects. Viral replication was suppressed, as evidenced by negative conversion of serum hepatitis B virus DNA in all the patients. Hepatic enzyme was also normalized. Modification of doses of immunosuppressant regimen was not required in using lamivudine in all patients. One patient experienced acute rejection and responded to solumedrol pulse therapy with normalization of graft function. Normal graft function was maintained in other patients while they were treated with lamivudine.

CONCLUSION

Lamivudine was a safe and effective therapy for activated hepatitis B in renal transplant recipients in the short term.

Chondroblastoma: MR characteristics with pathologic correlation

PURPOSE

The purpose of this study was to describe the MR findings of chondroblastoma with pathologic correlation.

METHOD

In 22 patients with pathologically proven chondroblastoma, MR signal characteristics were correlated with pathological findings.

RESULTS

On T2-weighted images, 12 (55%) lesions were hyperintense with hypointense areas in 9 lesions, whereas 10 (45%) were hypointense. Therefore, 19 of 22 (86%) lesions with pathologic correlation had hypointense areas entirely (n = 10) or partly (n = 9) on T2-weighted images. On gadolinium-enhanced images, 13 (59%) lesions showed lobular enhancement and 9 (41%) showed marginal and septal enhancement. Low signal intensity on T2-weighted MR images was most strongly associated with an abundance of immature chondroid matrix, hypercellularity of the chondroblasts, calcifications, and hemosiderin on histology.

CONCLUSION

Chondroblastoma was found to show hypointense portions on T2-weighted images. Signal intensity on T1- and T2-weighted MR images in chondroblastoma was dependent on the amounts of histopathological components.

Malignant fibrous histiocytoma at site of metal implant

The occurrence of malignant tumors at the site of metal implants is rare. The significance of this association is not settled. Its implications, however, are serious. A malignant fibrous histiocytoma arising at the site of an implant done 14 years ago for traumatic fracture of the femur in a 44-year-old man is reported. Previous reports are briefly summarized.

Effectiveness and safety of low-dose pravastatin and squalene, alone and in combination, in elderly patients with hypercholesterolemia

A double-blind, placebo-controlled study was conducted to compare the efficacy and safety of low-dose (10 mg) prevastatin and squalene (860 mg), either alone or in combination therapy, with placebo in the treatment of elderly patients with hypercholesterolemia. Ambulatory elderly patients (N = 102) were assigned in randomized fashion to receive active treatment or placebo for 20 weeks after a single-blind placebo lead-in period of 8 weeks. Total cholesterol and triglyceride levels in plasma were at least 250 mg/dL and less than 300 mg/dL, respectively. Concentrations of lipids and lipoproteins were measured, and clinical laboratory tests included liver function and creatine kinase determinations. Pravastatin 10 mg daily was more effective than squalene in reducing total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides and in increasing levels of high-density lipoprotein (HDL) cholesterol. Combination therapy significantly reduced total cholesterol and LDL cholesterol and increased HDL cholesterol to a greater extent than either drug alone. Adverse events and clinical laboratory abnormalities were generally mild and transient in all groups, and all but two patients finished the study. The incidence of side effects was low; myopathy did not occur. Coadministration of pravastatin and squalene combined the specific effects of the two drugs on lipoprotein concentrations. This combination may be useful and more cost-effective in elderly patients with hypercholesterolemia, who might have a higher incidence of side effects when using larger doses of pravastatin alone.

Expression of epidermal growth factor receptor in head and neck cancers correlates with clinical progression: a multicentre immunohistochemical study in the Asia-Pacific region

AIMS

With ongoing efforts to target the epidermal growth factor receptor (EGFR)-mediated tumour growth in the treatment of selected human malignancies, there is a need to determine the expression levels of EGFR and to evaluate its prognostic value in various malignancies in the Asia-Pacific region.

METHODS AND RESULTS

A total of 172 patients with head and neck squamous cell carcinomas from Australia, Hong Kong, Singapore, and Taiwan were selected for EGFR detection. Immunohistochemical staining was performed to evaluate EGFR expression. EGFR expression was present in 88.4% (152/172) of all cases tested. Specifically, EGFR expression was found in 91.3% (42/46), 84.6% (22/26), 84.1% (37/44), 96.0% (24/25), and 87.1% (27/31) cases of head and neck squamous cell carcinomas from the oral cavity, oropharynx, nasopharynx, hypopharynx, and larynx, respectively. The results demonstrate a stronger EGFR expression in T4 tumours (P=0.017) and later clinical stages (P=0.016). No significant correlation was seen with risk factors, primary tumour site and ethnicity.

CONCLUSIONS

The majority of head and neck squamous cell carcinomas express EGFR, indicating the importance of studying the efficacy of anti-cancer therapy through this pathway. The results also show similar rates of receptor expression in head and neck squamous cell carcinoma patients from our region compared with other parts of the world.

Differences in immunomodulating effects between wild and cultured Panax ginseng

The different effects between wild and cultured Panax ginseng on immunological activity were investigated. The extracts of hot water soluble fraction from wild Panax ginseng showed the mitogenic activity to lymphocytes but that from cultured Panax ginseng did not. The mitogenic activity of wild Panax ginseng (100 micrograms/well) was almost equal to Concanavalin A (0.1 microgram/well) which was well-known as one of T cell mitogens. The percentages of Thy 1.2-(pan T cells), L3T4-(helper T cells) and Lyt2-(cytotoxic T cells) positive cell population were significantly increased in the mice orally administered hot water soluble fraction from wild Panax ginseng as compared to control by 31.2, 17.9 and 30.1 percent, respectively.

Sequence variation of mitochondrial DNA control region in Koreans

The sequencing data for two mtDNA segments in control region I and II, 385 and 341 nucleotides long, respectively, for 306 unrelated Koreans are presented. In regions I and II, 139 and 58 polymorphic sites, respectively, were noted. These were distributed evenly along the control region, though the frequency of each site was variable. Nucleotide substitution rather than insertion/deletion was the prevalent pattern of variation. A total of 265 different mtDNA lineages in region I and 154 in region II were revealed. This result represents a substantial level of polymorphism in a defined population, and presents the possibility that mtDNA polymorphism could be used as an individual identification marker, especially when nuclear DNA is not available. In view of the complex pattern of variation, meticulous test-sequencing is thought to be more appropriate than RFLP analysis using restriction endonuclease or hybridization using an SSO probe. Racial differences with genealogical usage are also described.

Organophosphate-induced brain injuries: delayed apoptosis mediated by nitric oxide

The features of organophosphate-induced brain injuries were investigated. Rats were poisoned intraperitoneally with 9 mg/kg (1.8 LD(50)) of diisopropylfluorophosphate. Pyridostigmine bromide (0.1 mg/kg) and atropine methylnitrate (20 mg/kg), which are centrally inactive, were pre-treated intramuscularly to reduce the mortality and eliminate peripheral signs. Diisopropylfluorophosphate induced severe limbic seizures, and early necrotic and delayed apoptotic brain injuries. The necrotic brain injury was observed to be maximal as early as 1 h after diisopropylfluorophosphate treatment predominently in hippocampus and piriform/entorhinal cortices, showing a spongiform change (malacia) of neuropils in severe cases. In contrast, typical apoptotic (TUNEL-positive) cells started to appear at 12 h in thalamus, and a mixed type in amygdala. Separately, nitrite/nitrate content in cerebrospinal fluid was found to significantly increase after 2 h, reaching a maximal level at 6 h. Pre-treatment with l-N(G)-nitroarginine, an inhibitor of nitric oxide synthase, reduced nitrite/nitrate content and, noteworthy, attenuated only apoptotic brain injury in all four brain regions without affecting seizure intensity and necrotic injury. Taken together, the delayed apoptotic injury of brain induced by diisopropylfluorophosphate poisoning in rats might be mediated in part through nitric oxide production.

Adhesion molecules in skeletogenesis: I. Transient expression of neural cell adhesion molecules (NCAM) in osteoblasts during endochondral and intramembranous ossification

We report that neural cell adhesion molecules (NCAM) are expressed transiently in developing chicken osteoblasts during osteogenesis using immunostaining on cryostat sections. NCAM is strongly expressed in most osteoblasts along bone trabeculae that coincide with the presence of collagen I and alkaline phosphatase activity. In endochondral ossification, NCAM is highly expressed in osteogenic buds as seen in the epiphysis and diaphysis of tibia and vertebrae. In intramembranous ossification, NCAM is seen in osteogenic condensation of calvaria and in the periosteum of tibial diaphysis. The expression is transient because NCAM is not expressed in mesenchymal cells before osteogenic condensation and NCAM expression is lost in osteocytes in later stages. The staining pattern suggests that NCAM is present on the cell membrane of osteoblasts. Using a specific monoclonal antibody, the osteoblast NCAM is shown to contain polysialic acid, which is enriched in embryonic brain. Northern blot analysis using chicken brain NCAM cDNA as probes showed two major sizes of mRNA at 6.4 and 4.2 kb in calvarial mRNA as opposed to bands at 7.2, 6.4, and 4.2 kb in the brain. An immunoblot showed major proteins at Mr 165 and 110 kd, unlike brain NCAM, which are 180, 140, and 120 kD. That NCAM is involved in bone morphogenesis is consistent with the general hypothesis that NCAM plays pivotal roles in mesenchymal condensation, as shown in the formation of muscle, kidney, skin, and cartilage. The results establish NCAM as a cell surface molecule expressed transiently during osteoblast lineage. The implication that NCAM may mediate osteoblast interaction and regulate skeletal morphogenesis is discussed.

Electron microscopic studies on the alveolar-capillary barrier in the patients of chronic pulmonary edema

Electron microscopic studies on the alveolar-capillary barrier were carried out in 13 patients of chronic pulmonary edema and/or congestion resulting from heart disease of various etiologies. The characteristic findings are tremendous proliferation of type II granular pneumocyte and irregular thickening of alveolar epithelial and capillary basement membrane. These ultrastructural changes correlated to the duration of heart failure and mean pulmonary arterial wedge pressure despite of disease groups and the age of the patients. In particular, lamination of capillary basement membrane with fragmentation was more specific finding which was observed only in patients with mean pulmonary arterial wedge pressure above 35 mmHg and duration of heart failure over 6 hears. There was no apparent relationship existed between the ultrastructural changes and pulmonary arterial pressure. In addition to these characteristic changes the remaining ultrastructural changes of the alveolar-capillary barrier were difficult to make a correlation to clinical course and cardio-pulmonary hemodynamics.

Abnormal cardiovascular reflex tests are predictors of mortality in Type 2 diabetes mellitus

AIMS

To determine whether diabetic autonomic neuropathy is an important factor contributing to mortality in Type 2 diabetes mellitus.

METHODS

Between 1989 and 1993, 431 men and 181 women with Type 2 diabetes were given diabetic autonomic neuropathy cardiovascular reflex (CVR) tests. These subjects were followed for the subsequent 5--9 years to assess mortality rates.

RESULTS

The prevalence rate of abnormal CVR tests was 46.1% in patients with the history of diabetes less than 5 years and up to 69.4% when the history of diabetes exceeded 20 years. During the follow-up period from 1 January 1989 to 31 December 1997 (mean 7.7 years), a total of 135 participants died. The 8-year survival rate for patients with abnormal CVR tests was 63.6% in males and 76.4% in females, compared with 80.9 and 93.3% for patients with normal CVR tests. The results were grouped as: group 1, normal CVR tests without postural hypotension (PHT); group 2, normal CVR tests with PHT; group 3, abnormal CVR tests without PHT; and group 4, abnormal CVR tests with PHT. The 8-year survival rate was 85.4% in group 1, 80.9% in group 2, 74.5% in group 3 and 61.1% in group 4.

CONCLUSION

Type 2 diabetic patients with abnormal CVR tests may have increased mortality, and those combined with postural hypotension have higher mortality than those without. Abnormal CVR tests may be important predictors of mortality in Type 2 diabetes mellitus.

Measurement of an exceptionally weak electron-phonon coupling on the surface of the topological insulator Bi2Se3 using angle-resolved photoemission spectroscopy

Gapless surface states on topological insulators are protected from elastic scattering on nonmagnetic impurities which makes them promising candidates for low-power electronic applications. However, for widespread applications, these states should have to remain coherent at ambient temperatures. Here, we studied temperature dependence of the electronic structure and the scattering rates on the surface of a model topological insulator, Bi2Se3, by high-resolution angle-resolved photoemission spectroscopy. We found an extremely weak broadening of the topological surface state with temperature and no anomalies in the state's dispersion, indicating exceptionally weak electron-phonon coupling. Our results demonstrate that the topological surface state is protected not only from elastic scattering on impurities, but also from scattering on low-energy phonons, suggesting that topological insulators could serve as a basis for room-temperature electronic devices.

Palmar hyperhidrosis in children: treatment with video endoscopic laser sympathectomy

Palmar hyperhidrosis (PH) often starts in childhood and can be a disabling condition for a significant number of young children at the age they begin primary school. There are few reports regarding the surgical treatment of PH in children. The authors report on 40 PH patients under 16 years of age treated with video thoracoscopic laser sympathectomy; there has been substantial experience with this procedure for the treatment of adults with PH. A satisfactory result, with very low morbidity, was achieved for all 40 children. The surgical technique is described briefly. With the technique, the proper sympathetic segment is visualized in almost all cases and then definitely ablated with a fiberoptic low-power laser while under the aid of sympathetic monitoring. Consequently, an adequate sympathectomy warranting a long-lasting therapeutic effect can be achieved without the need of tissue diagnosis. No case required conversion to open sympathectomy. Neither injury to the lung nor bleeding was encountered. Horner's syndrome did not occur in any case. Bilateral sympathectomy was accomplished generally within 30 minutes. All patients were discharged after an overnight stay and are doing well with normal activities. The most frequent complication was compensatory hyperhidrosis, which was tolerable after reassurance. Based on the accumulated experience, it is justified to recommend early surgery, with this refined technique, in cases of severe PH in children.

Sequential changes in hepatocarcinogenesis induced by diethylnitrosamine plus thioacetamide in Fischer 344 rats: induction of gankyrin expression in liver fibrosis, pRB degradation in cirrhosis, and methylation of p16(INK4A) exon 1 in hepatocellular carcinoma

To clarify the sequential changes in pRB and p16 during different stages of hepatocarcinogenesis such as fibrosis, cirrhosis, hepatocellular adenoma (HCA), and hepatocellular carcinoma (HCC), male Fischer 344 rats were singly injected with diethylnitrosamine (DEN), immediately followed with phenobarbital for 1 wk and then thioacetamide (TAA) for 39 wk in drinking water. Rats were killed at 9, 20, 30, and 40 wk after DEN initiation and changes of pRB level, p16 gene hypermethylation, and in vivo gankyrin expression were examined. Histologic examination showed stepwise appearances of fibrosis, cirrhosis, HCA, and HCC at weeks 9, 20, 30, and 40, respectively. Hypermethylation of p16 exon 1 was not found until HCA but appeared in 50% of the rats with HCC accompanied by complete loss of its mRNA expression. The amount of glutathione S-transferase--gankyrin bound to pRB and pRB degradation in the liver depended on the concentration of gankyrin and incubation time. Gankyrin expression preceded pRB degradation in liver cirrhosis. In conclusion, gankyrin expression induced in liver fibrosis accelerated the degradation of pRB during liver cirrhosis, and inactivation of p16 exon 1 by DNA hypermethylation occurred during the progression of tumor cells to poorly differentiated HCC. Inactivation of pRB and/or p16 resulted in complete loss of regulation in the cell-division cycle during early and late stages, respectively, of hepatocarcinogenesis. Mol. Carcinog. 30:138--150, 2001.

Grapefruit juice and its flavonoids inhibit 11 beta-hydroxysteroid dehydrogenase

INTRODUCTION

The enzyme 11 beta-hydroxysteroid dehydrogenase (11 beta-OHSD) oxidizes cortisol to inactive cortisone. Its congenital absence or inhibition by licorice increases cortisol levels at the mineralocorticoid receptor, causing mineralocorticoid effects. We tested the hypothesis that flavonoids found in grapefruit juice inhibit this enzyme in vitro and that grapefruit juice itself inhibits it in vivo.

METHODS

Microsomes from guinea pig kidney cortex were incubated with cortisol and nicotinamide adenine dinucleotide (NAD) or nicotinamide adenine dinucleotide phosphate (NADP) and different flavonoids and the oxidation to cortisone measured with use of HPLC analysis. In addition, healthy human volunteers drank grapefruit juice, and the ratio of cortisone to cortisol in their urine was measured by HPLC and used as an index of endogenous enzyme activity.

RESULTS

Both forms of 11 beta-OHSD requiring either NAD or NADP were inhibited in a concentration-dependent manner by the flavonoids in grapefruit juice. Normal men who drank grapefruit juice had a fall in their urinary cortisone/cortisol ratio, suggesting in vivo inhibition of the enzyme.

CONCLUSION

Dietary flavonoids can inhibit this enzyme and, at high doses, may cause an apparent mineralocorticoid effect.

Molecular characterization of myocardial fibrosis during hypothyroidism: evidence for negative regulation of the pro-alpha1(I) collagen gene expression by thyroid hormone receptor

The purpose of this study was to gain insights into the underlying mechanism of myocardial fibrosis during hypothyroidism. Treatment of cardiac fibroblasts with a medium lacking thyroid hormone led to a 47% increase in [3H]thymidine incorporation into the cell nuclei compared with that in untreated cells. Northern blot analysis of RNA from cardiac fibroblasts grown in a thyroid hormone depleted medium resulted in a 38% increase in the abundance of mRNA for pro-alpha1(I) collagen. At the protein level, the amount of type I collagen, as determined by immunoprecipitation, was increased either in the cell lysate (46%) of cardiac fibroblasts grown in a thyroid hormone depleted medium or in the medium (44%). The chimeric plasmid, ColCAT 3.6, contains the 5'-flanking region of the rat pro-alphal(I) collagen gene (from bases -3520 to +115) fused to the chloramphenicol acetyltransferase (CAT) gene. The plasmid was cotransfected with thyroid hormone receptor (TR) expression plasmid into rat cardiac fibroblasts and COS-l cells (monkey mesangial cells). Cells transfected with the ColCAT plasmid in the presence of thyroid hormone (100 nM T(3)) had a significant decrease (39% in fibroblasts, P<0.01; 52% in COS-1 cells, P<0.001) in CAT activity when compared to cells not exposed to thyroid hormone. Transient co-transfection of TR with various pro-alphal(I) collagen/CAT deletion constructs showed that T(3)-dependent repression was preserved with the deletion from 3520 bp of the flanking sequence to a 5' end point at position -224, indicating that a thyroid hormone-response element (TRE) was localized at the region -224 to +115. The TR-DNA binding assays demonstrated binding of the human TRbeta1 to a fragment containing a proposed TRE located between position -35 and +115 in the 5'-flanking region of the rat pro-alphal(I) collagen gene.

In vitro growth inhibition of growth factor-stimulated meningioma cells by calcium channel antagonists

Studies have shown that a majority of meningiomas contain receptors for platelet-derived growth factor and epidermal growth factor and that these growth factors promote the proliferation of meningioma cells in culture. Although the mechanism of action has not been elucidated, intracellular calcium appears to be part of the signal transduction mechanism. Because alterations in intracellular calcium could interrupt this pathway and decrease cellular proliferation, we investigated the effects of calcium channel-blocking agents on the growth of meningioma cells in vitro. Primary meningioma cell cultures were established, and the cells were characterized by light and electron microscopy and by immunohistochemical studies. Then, the cultures were given growth factors and/or various calcium channel antagonists, and growth rates were measured. A dose-response decrease in cell growth was seen when verapamil, nifedipine, or diltiazem (voltage-dependent calcium channel-blocking agents) was added to serum-containing media. Also, these drugs blocked the growth stimulation of epidermal growth factor and platelet-derived growth factor in a similar fashion. Dantrolene, which inhibits the release of sequestered intracellular calcium, was also an effective blocker of the mitogenic stimulation of these growth factors.

Glibenclamide induces apoptosis through inhibition of cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channels and intracellular Ca(2+) release in HepG2 human hepatoblastoma cells

Glibenclamide, an inhibitor of cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channels, induced apoptosis in a dose- and time-dependent manner in HepG2 human hepatoblastoma cells. Glibenclamide increased intracellular Ca(2+) concentration, which was significantly inhibited by Ca(2+) release blockers dantrolene and TMB-8. BAPTA/AM, an intracellular Ca(2+) chelator, and the Ca(2+) release blockers significantly inhibited glibenclamide-induced apoptosis. Glibanclamide also increased intracellular Cl(-) concentration, which was significantly blocked by CFTR Cl(-) channel activators levamisole and bromotetramisole. These activators also significantly inhibited both intracellular Ca(2+) release and apoptosis induced by glibenclamide. The expression of CFTR protein in the cells was confirmed by Western blot analysis. These results suggest that glibenclamide induced apoptosis through inhibition of CFTR Cl(-) channels and intracellular Ca(2+) release and that this protein may be a good target for treatment of human hepatomas.

Dynamics of proton transfer in bacteriorhodopsin

Proton transfer in bacteriorhodopsin from the cytoplasm to the extracellular side is initiated from protonated asp96 in the cytoplasmic region toward the deprotonated Schiff base. This occurs in the transition from the photocycle late M state to the N state. To investigate this proton-transfer process, a quantum mechanics/molecular mechanics (QM/MM) model is constructed from the bacteriorhodopsin E204Q mutant crystal structure. Three residues, asp96, asp85, and thr89, as well as most of the retinal chromophore and the Schiff base link of lys216 are treated quantum mechanically and connected to the remaining classical protein through linker atom hydrogens. Structural transformation in the M state results in the formation of a water channel between the Schiff base and asp96. Since a part of this channel is lined with hydrophobic residues, there has been a question on the mechanism of proton transfer in a hydrophobic channel. Ab initio dynamics using the CHARMM/GAMESS methodology is used to simulate the transfer of the proton through a partially hydrophobic channel. Once sufficient water molecules are added to the channel to allow the formation of a single chain of waters from asp96 to the Schiff base, the transfer occurs as a fast (less than a picosecond) concerted event irrespective of the protonation state of asp85. Dynamic transfer of the proton from asp96 to the nearest water initiates the organization of a strongly bonded water chain conducive to the transfer of the proton to the Schiff base nitrogen.