Cytotoxicity of sodium fluoride on human oral mucosal fibroblasts and its mechanisms

Because sodium fluoride (NaF) is widely used for prevention of dental caries, pathobiological effects of NaF were investigated on human oral mucosal fibroblasts. The results showed that NaF was cytotoxic to oral mucosal fibroblasts at concentrations of 4 mmol/L or higher. Exposure of cells to NaF for 2 h also inhibited protein synthesis, cellular ATP level and functional mitochondrial activities in a dose-dependent manner. However, incubation of cells with NaF up to 12 mmol/L for 2 h depleted only 13% of cellular glutathione level. The IC50 of NaF on cellular ATP level was about 5.75 mmol/L. Preincubation of the cells with pyruvate and succinate did not protect cells from NaF-induced ATP depletion. At concentrations of 4 mmol/L, 8 mmol/L and 12 mmol/L, NaF inhibited 31%, 56% and 57% of mitochondrial functions, respectively, after 2 h incubation. No significant inhibition for NaF was found at concentrations lower than 2 mmol/L (40 ppm). These results indicate that NaF can be toxic to oral mucosal fibroblasts in vitro by its inhibition of protein synthesis, mitochondrial function and depletion of cellular ATP. Because of repeated and long-term usage of NaF, more detailed studies should be undertaken to understand its toxic effects in vitro and in vivo.

Dynamics of docosahexaenoic acid metabolism in the central nervous system: lack of effect of chronic lithium treatment

Using a method and model developed in our laboratory to quantitatively study brain phospholipid metabolism, in vivo rates of incorporation and turnover of docosahexaenoic acid in brain phospholipids were measured in awake rats. The results suggest that docosahexaenoate incorporation and turnover in brain phospholipids are more rapid than previously assumed and that this rapid turnover dilutes tracer specific activity in brain docoshexaenoyl-CoA pool due to release and recycling of unlabeled fatty acid from phospholipid metabolism. Fractional turnover rates for docosahexaenoate within phosphatidylinositol, choline glycerophospholipids, ethanolamine glycerophospholipids and phosphatidylserine were 17.7, 3.1, 1.2, and 0.2 %.h(-1), respectively. Chronic lithium treatment, at a brain level considered to be therapeutic in humans (0.6 micromol.g(-1)), had no effect on turnover of docosahexaenoic acid in individual brain phospholipids. Consistent with previous studies from our laboratory that chronic lithium decreased the turnover of arachidonic acid within brain phospholipids by up to 80% and attenuated brain phospholipase A2 activity, the lack of effect of lithium on docosahexaenoate recycling and turnover suggests that a target for lithium's action is an arachidonic acid-selective phospholipase A2.

Effects of areca nut, inflorescence piper betle extracts and arecoline on cytotoxicity, total and unscheduled DNA synthesis in cultured gingival keratinocytes

Betel quid (BQ) chewing has a strong correlation with oral leukoplakia, submucous fibrosis and oral cancer. For elucidation of its pathogenesis, we investigated the effects of areca nut (AN) and inflorescence piper betle (IPB) extracts and arecoline on the growth, total DNA synthesis (TDS) and unscheduled DNA synthesis (UDS) of cultured human gingival keratinocytes (GK). Arecoline and AN extract suppressed the growth of GK over 5 days of incubation in a dose-dependent fashion. At concentrations of 100, 200 and 400 microg/ml, AN extract suppressed the growth of GK by 31%, 46% and 90%, respectively. The IPB extracts exerted less inhibitory effect on the growth of GK. IPB extract (200-400 microg/ml) decreased cell numbers by 20-40% over 5 days of incubation. Moreover, at a concentration of 0.1, 0.2 and 0.4 mM, arecoline suppressed cell growth by 44%, 77% and 96%, respectively. However, only AN extract induced TDS and UDS in cultured GK within 6 h of exposure. Induction of UDS by AN extract was concomitant with the presence of apparent intracellular vacuolization. Arecoline was also toxic to GK, but did not induce intracellular vacuolization. At a concentration range of 200-1600 microg/ml, AN extract induced TDS by 2.1- to 6.5-fold. Furthermore, at a concentration of 400-1600 microg/ml, AN extract elevated the UDS by 2.4- to 5.5-fold more than that of untreated control. On the contrary, IPB extract (200-1600 microg/ml) and arecoline (0.2-1.6 mM) inhibited the TDS and UDS of GK to a different extent. Simultaneous exposure of confluent GK to AN extract, IPB extract and arecoline for 1 to 5 days led to different degrees of cytotoxicity that was dose- and time-dependent. These results indicate that AN, IPB and arecoline take part in the pathogenesis of BQ chewing-related oral mucosal lesions, possibly through both genotoxic and non-genotoxic mechanisms.

Thrombin activates the growth, cell-cycle kinetics, and clustering of human dental pulp cells

Thrombin is activated during vascular injury and inflammation of the dental pulp. In the present study, we found that thrombin can stimulate the proliferation of pulp cells in a dose-dependent manner as analyzed by modified MTT assay. The cell number increased by 1.6, 1.77, and 2.14-fold over that of control after exposure to 5, 10, and 20 units/ml of thrombin for 5 days. Flow cytometry studies also found that thrombin (10 units/ml) can induce the cell cycle progression of pulp cells after 24 h of incubation, as revealed by increasing the proportion of cells in the S phase and the G2/M phase from 29 to 72%. Moreover, exposure to thrombin (> 5 units/ml) for 3 days led to marked clustering of pulp cells. We concluded that thrombin can regulate the growth, cell cycle progression, and functional reorganization of the pulp tissue during pulp healing and inflammatory processes.

Cloning and complete nucleotide sequence of Acinetobacter radioresistens CMC-1 AglyA gene encoding serine hydroxymethyltransferase

A gene (AglyA) encoding serine hydroxymethyltransferase of Acinetobacter radioresistens CMC-1 was cloned and sequenced. Nucleotide sequence analysis of AglyA predicted a single open reading frame (ORF) of 1251 bp encoding a 417-amino acid polypeptide. Two putative MetR-like binding sites (5'-TGAAACATGAGCT) and (5'-TGAGCAAAGTTCA), centered at bp -123 and -95 relative to the +1 translation start site were found, which have six out of nine and eight out of nine nucleotides that match to the consensus sequence of Escherichia coli (5'-TGAANNT/ANNTTCA), respectively. The enzyme also showed a high level of homology to other sources of serine hydroxymethyltransferase proteins.

Discordance between uterine cervical cytology and biopsy: results and etiologies of a one-year audit

To investigate the etiologies of discrepancies between cervicovaginal smear and corresponding cervical biopsy results, a total of 15,474 cervicovaginal smears were sampled in a one-year period. Among these, 427 patients were diagnosed with atypical squamous cells of undetermined significance (ASCUS), dysplasia, or malignancy. The screen positive rate was 2.8%. All of the positive cases had histologic follow-up. Forty-nine of the 427 patients had a discrepancy of at least two grades (the grades are divided to negative, ASCUS, mild dysplasia, moderate dysplasia, severe dysplasia and invasive carcinoma), between the cytologic and histologic diagnoses. The discrepancy rate was 11.5%. Ten of these discrepant cases had poorly-preserved slides or a not definitely final diagnosis. A total of 39 cases (79.6%) of discrepancy were reviewed in this study. In thirty (77%) of the 39 discrepant cases, the errors were cytologic and in 9 cases (23%) the errors were histologic. Cytologic error was the major cause of cytohistologic discrepancy. The etiologies of cytohistologic discrepancy included: cytologic interpretation error, 17 cases (44%); cytologic sampling error, 10 cases (25%); biopsy sampling error, 6 cases (15%); cytologic screen error, 3 cases (8%); and biopsy interpretation error, 3 cases (8%). The major etiology of cytohistologic discordances was cytologic interpretation error. In this retrospective study, we determined the etiologies of cytohistologic discrepancies. This information can be useful for improving diagnostic accuracy and the quality of patient care.

Percutaneous A1 pulley release for trigger digits

BACKGROUND

Recently, percutaneous trigger digit release has been reported as a safe, effective office procedure. The purpose of this study was to further assess the safety and efficacy of this technique.

METHODS

From November, 1996, to August, 1997, 69 consecutive patients with 71 primary trigger digits were treated with percutaneous A1 pulley release. The operations were performed using the tip of a 19-gauge needle, mounted on a 3-ml syringe. The mean age of the patients was 66 years. The mean duration of follow-up was 21 weeks. The patients were prospectively classified into two groups according to age, sex, digit involved, duration of symptoms and whether or not they had had previous local steroid injection.

RESULTS

Sixty-three digits were completely free of triggering. Residual triggering or inadequate release was found in eight digits at final follow-up. The success rate was not associated with sex, age, digit involved, duration of symptoms or history of local steroid injection. No major complications were found in this study, but minor complications included persistent local tenderness in nine digits and subcutaneous hematoma in six digits. Risk factors related to persistent local tenderness were female gender and trigger thumb.

CONCLUSIONS

Percutaneous A1 pulley release is an effective, safe and convenient procedure for the treatment of trigger digits.

Helicobacter pylori stool antigen (HpSA) test--a simple, accurate and non-invasive test for detection of Helicobacter pylori infection

BACKGROUND/AIMS

To access the reliability of a newly developed test, the Helicobacter pylori (H. pylori) stool antigen (HpSA) test was used for detection of H. pylori infection.

METHODOLOGY

Stool specimens were collected from 33 consecutive patients (19 males and 14 females, age range: 16-73 years, mean: 49 years) who received upper gastrointestinal endoscopic examination for gastrointestinal symptoms. The H. pylori status was evaluated based on six different tests: culture, histology, biopsy urease test, 13C-urea breath test (13C-UBT), serology, and HpSA test. A commercial kit using an enzyme-linked immunosorbent assay examined HpSA in the stool. H. pylori status was defined as positive when the culture was positive or concordance of three of the other four tests (histology, biopsy urease test, 13C-UBT, and serology) was positive.

RESULTS

Twenty patients were diagnosed as H. pylori-positive. The HpSA test was positive in 19 patients and negative in 14 patients. The sensitivity and specificity were 95.0% and 100%, respectively. The overall accuracy rate was 96.3%.

CONCLUSIONS

The HpSA test is a new, simple, non-invasive method for accurate diagnosis of H. pylori infection.

Expression and export of Pseudomonas putida NTU-8 creatinase by Escherichia coli using the chitinase signal sequence of Aeromonas hydrophila

The gene for the creatinase from Pseudomonas putida NTU-8 was sequenced and revealed an open reading frame (ORF) of 1209 base pairs encoding a polypeptide of 403 amino acids with a calculated molecular weight (M(r)) of 45,691. The deduced amino acid sequence is very similar to that of the creatinase of Pseudomonas putida and Flavobacterium sp. An overproduction system for the chitinase signal peptide--creatinase hybrid gene was constructed by using the pQE-51 expression vector in E. coli JM109. The amount of this fusion enzyme was about 50% exported into the periplasmic space of E. coli.

Detection of human papillomavirus types in cervical adenocarcinoma by the polymerase chain reaction

OBJECTIVE

To determine the human papillomavirus (HPV) types in cervical adenocarcinoma of patients from Taiwan.

METHODS

DNA was extracted from fixed tissues and polymerase chain reaction was performed in conjunction with a unique probe, pRSA I, allowing simultaneous detection of HPV types 6, 11, 16, 18, 31 and 33 from amplified HPV DNAs after endonuclease, RsaI, digestion.

RESULTS

Of 69 tissues examined, 31.9% (22/69) were found to contain HPV DNA. Among 22 HPV-positive specimens, no HPV types 6, 11, 31 and 33 were detected. On the other hand, HPV 16 and HPV 18 were found in 11 (15.9%) and 10 (14.5%) of HPV-positive specimens, respectively. One specimen (1.5%) was found to contain both HPV 16 and 18 DNAs.

CONCLUSIONS

Our findings support that HPV 18, along with HPV 16, may play a certain role in the adenocarcinoma pathogenesis of the uterine cervix.

Computerized tomography in the diagnosis of subluxation of the distal radioulnar joint

BACKGROUND

The diagnosis of distal radioulnar joint (DRUJ) subluxation is difficult. Routine radiographs are imprecise in clinical analysis. However, the anatomy and dynamic configuration of this articulation have been clearly defined utilizing computerized tomography (CT). Three CT criteria for the evaluation of DRUJ subluxation have been reported: Mino's criteria, the epicenter method and the congruity method. Previous reports discussed these criteria in the analysis of symptomatic DRUJ, but no clear conclusion has been reached. The purpose of this study is to investigate accurate criteria of CT in defining subluxation of the DRUJ.

METHODS

Eighty distal radioulnar joints in 40 patients with suspected DRUJ subluxation underwent CT scans of both symptomatic and asymptomatic wrists. The CT scan was obtained through the DRUJ with the forearm in neutral rotation, active full supination and active full pronation. Three CT criteria were used to assess the DRUJ in all positions of unstable and normal wrists.

RESULTS

Overall, 54 wrists were included in the final analysis. Seventeen symptomatic wrists had frank DRUJ instability diagnosed from true lateral radiographs, and 11 were reconfirmed from intraoperative pathology. The other 37 wrists had normal DRUJ. Among the three methods, the epicenter method had similar sensitivity to Mino's criteria and the congruity method. However, the epicenter method had much better specificity than Mino's criteria and the congruity method.

CONCLUSIONS

For accurate diagnosis of subluxation of the DRUJ, CT scan through the symptomatic DRUJ in neutral rotation, active full supination, active full pronation and analysis with the epicenter method are recommended.

Cytotoxicity of sodium fluoride on human oral mucosal fibroblasts and its mechanisms

Because sodium fluoride (NaF) is widely used for prevention of dental caries, pathobiological effects of NaF were investigated on human oral mucosal fibroblasts. The results showed that NaF was cytotoxic to oral mucosal fibroblasts at concentrations of 4 mmol/L or higher. Exposure of cells to NaF for 2 h also inhibited protein synthesis, cellular ATP level and functional mitochondrial activities in a dose-dependent manner. However, incubation of cells with NaF up to 12 mmol/L for 2 h depleted only 13% of cellular glutathione level. The IC50 of NaF on cellular ATP level was about 5.75 mmol/L. Preincubation of the cells with pyruvate and succinate did not protect cells from NaF-induced ATP depletion. At concentrations of 4 mmol/L, 8 mmol/L and 12 mmol/L, NaF inhibited 31%, 56% and 57% of mitochondrial functions, respectively, after 2 h incubation. No significant inhibition for NaF was found at concentrations lower than 2 mmol/L (40 ppm). These results indicate that NaF can be toxic to oral mucosal fibroblasts in vitro by its inhibition of protein synthesis, mitochondrial function and depletion of cellular ATP. Because of repeated and long-term usage of NaF, more detailed studies should be undertaken to understand its toxic effects in vitro and in vivo.

Pharmacokinetics of methyl palmoxirate, an inhibitor of beta-oxidation, in rats and humans

Recent studies from our laboratory have shown that methyl palmoxirate (MEP), an inhibitor of mitochondrial beta-oxidation of long chain fatty acids, can be used to increase incorporation of radiolabeled palmitic acid into brain lipids and reduce beta-oxidation of the fatty acid. Thus, MEP allows the use of carbon labeled palmitate for studying brain lipid metabolism in animals and humans by quantitative autoradiography or positron emission tomography (PET). As it is essential to pretreat human subjects with an acute dose of MEP prior to intravenous injection of [1-11C]palmitate for PET scanning, this study was undertaken to determine the plasma elimination half-life of MEP in rats and human subjects and to provide insight about the drug's absorption and metabolism. A gas chromatographic method was developed to measure MEP in body fluids. Following oral administration of MEP to rats (2.5 and 10 mg/kg) and to humans, the unmetabolized drug could not be detected in plasma or urine (sensitivity of detection was 1 ng). However, when MEP was injected intravenously (10 mg/kg) in rats, a peak initial concentration could be measured in plasma (7.7 microg/mL), the clearance of the drug from plasma was rapid (t1/2 = 0.6 min), which indicates that MEP readily enters tissue lipid pools or is metabolized like long-chain fatty acids. As no adverse experience occured in the 11 human subjects studied, oral administration of a single dose of MEP was safe under the conditions of this study and may be used to increase the incorporation of positron labeled palmitic acid for studying brain lipid metabolism in vivo by PET.

Batch phenol degradation by candida tropicalis and its fusant

Phenol degradation by Candida tropicalis and its fusant, which is produced using protoplast fusion as a selective technique, is evaluated under batch and high concentration conditions. The respirometric data show that oxygen uptake activities of both yeast strains peak at pH 7.0 and 32 degrees C, but the fusant is more active than the control strain. Although the data show that both yeast strains are capable of sustaining discernible degradation in the presence of phenol inhibition, however, the C. tropicalis fusant is capable of attaining better phenol degradation than the control strain and it is less susceptible to phenol inhibition. Under the conditions tested, C. tropicalis is completely inhibited at phenol concentrations >/=3,300 mg/L, whereas for the C. tropicalis fusant complete inhibition is absent until phenol concentrations are >/=4, 000 mg/L. The observed cell yields of both yeast strains are virtually identical and remain fairly constant at approximately 0.5 mg MLVSS/mg C6H5OH (MLVSS: mixed liquor volatile suspended solids). Copyright 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 391-395, 1998.

Thrombin-induced DNA synthesis of cultured human dental pulp cells is dependent on its proteolytic activity and modulated by prostaglandin E2

To clarify the roles of alpha-thrombin and prostaglandin E2 (PGE2) in the healing and inflammatory processes of dental pulp, their effects on the DNA synthesis of human pulp cells were investigated by measurement of [3H]thymidine incorporation. At a concentration range of 1 to 25 units/ml, alpha-thrombin stimulated DNA synthesis of the pulp cells by 1.5 to 2.6-fold. On the contrary, PGE2 (> 0.05 microgram/ml) suppressed DNA synthesis by 24 to 39%. Using reverse transcriptase-polymerase chain reaction, thrombin receptor mRNA expression was identified in the pulp cells. Furthermore, alpha-thrombin-induced DNA synthesis could be inhibited by antithrombin III (2 units/ml) with heparin (2 units/ml) or D-Phe-Pro-ArgCH2Cl (50 micrograms/ml). PGE2 (0.1 to 0.5 microgram/ml) also inhibited the thrombin-induced DNA synthesis by 39 to 64%. These results imply that pulp cells express the thrombin receptor that is activated by the serine protease activity of thrombin. Interactions of thrombin and PGE2 are important in modulating the inflammatory and healing processes of the pulp.

Right ventricular end-diastolic volume index as a predictor of preload status in patients on positive end-expiratory pressure

OBJECTIVE

To evaluate the clinical utility of right ventricular end-diastolic volume index (RVEDVI) and pulmonary artery occlusion pressure (PAOP) as measures of preload status in patients with acute respiratory failure receiving treatment with positive end-expiratory pressure.

DESIGN

Prospective, cohort study.

SETTING

Surgical intensive care unit in a Level I trauma center/university hospital.

PATIENTS

Sixty-four critically ill surgical patients with acute respiratory failure.

INTERVENTIONS

All patients were treated for acute respiratory failure with titrated levels of positive end-expiratory pressure (PEEP) with the goal of increasing arterial oxygen saturation to > or =0.92, reducing FIO2 to <0.5, and reducing intrapulmonary shunt to < or =0.2. Serial determinations of RVEDVI, PAOP, and cardiac index (CI) were recorded.

MEASUREMENTS AND MAIN RESULTS

Two hundred-fifty sets of hemodynamic variables were measured in 64 patients. The level of PEEP ranged from 5 to 50 cm H2O (mean 12+/-9 [SD] cm H2O). At all levels of PEEP, CI correlated significantly better with RVEDVI than with PAOP. At levels of PEEP > or =15 cm H2O, CI was inversely correlated with PAOP, but remained positively correlated with RVEDVI.

CONCLUSIONS

CI correlates significantly better with RVEDVI than PAOP at all levels of PEEP up to 50 cm H2O. RVEDVI is a more reliable predictor of volume depletion and preload recruitable increases in CI, especially in patients receiving higher levels of PEEP where PAOP is difficult to interpret.

Threshold values of intramucosal pH and mucosal-arterial CO2 gap during shock resuscitation

BACKGROUND

The gastric intramucosal pH (pHi) and gastric mucosal-arterial CO2 gap (GAP) estimate visceral perfusion and predict outcome. Threshold values of these variables for use during resuscitation, however, remain poorly defined. The purpose of this study was to develop clinically derived cutoffs for both pHi and GAP for predicting death and multiple organ failure (MOF) in trauma patients.

METHODS

This was a cohort study of 114 consecutive trauma patients who had pHi determined at 24 hours after intensive care unit admission. The corresponding GAP for each of these values of pHi was obtained through chart review. Receiver operating characteristic curves were constructed for both pHi and GAP with respect to death and MOF. These curves were used to determine the value of each variable that maximized the sum of sensitivity and specificity in predicting outcome. chi2 tests and odds ratios were used to determine if significant differences in outcome occurred above and below these cutoff values.

RESULTS

Of 114 patients who had pHi determined at 24 hours after admission, 108 had corresponding GAP values available. The values of pHi and GAP that maximized sensitivity and specificity were 7.25 and 18 mm Hg, respectively. The odds ratio for pHi versus death was 4.6 and for pHi versus MOF was 4.3. The odds ratios for GAP versus death and MOF were 2.9 and 3.3, respectively.

CONCLUSION

In trauma patients, the ability to predict death and MOF is maximized at values of pHi less than 7.25 and GAP greater than 18 mm Hg. These values represent clinically derived cutoffs that should be useful for evaluating the adequacy of intestinal perfusion during resuscitation.

Fatty acid incorporation depicts brain activity in a rat model of Parkinson's disease

Following pulse labeling with [3H]arachidonic acid ([3H]AA), its incorporation pattern in brain reflects regional changes in neurotransmitter signal transduction using phospholipase A2, that is, functional activity. In a rat model of Parkinson's disease, unilateral 6-hydroxydopamine lesion in the substantia nigra, [3H]AA acid incorporation from blood was increased in cerebral cortex, caudate putamen, globus pallidus, entopeduncular nucleus, subthalamic nucleus and substantia nigra pars reticulata ipsilateral to the lesion. This increased [3H]AA incorporation likely reflects disinhibition of basal ganglia and cortical circuits secondary to absent inhibitory nigrostriatal dopaminergic input.

Fine-needle aspiration cytology of retroperitoneal extramedullary hematopoiesis: a case report

We report a 69 year-old man with left renal hilar tumor, which was incidentally detected and clinically suspected to be malignant. Interpretations of fine-needle aspiration (FNA) and frozen section of this tumor were not conclusive, and originally malignancy could not be ruled out. Later, correlation with the patient's history and bone marrow biopsy with cytological and histological pictures resulted in the diagnosis of a tumor of extramedullary hematopoiesis (EMH). This case shows that FNA cytology may be a useful method for diagnosing EMH. However, we also demonstrate the potential pitfall of misdiagnosing atypical megakaryocytes as malignant cells on FNA smears, or even in frozen sections, when clinical history and clinical data are not available. EMH should be considered in the differential diagnosis of patients with bone marrow disorders and mass lesions in extramedullary sites.

Effects of thrombin on the growth, protein synthesis, attachment, clustering and alkaline phosphatase activity of cultured human periodontal ligament fibroblasts

Previous studies have indicated that thrombin can activate pulp cells, including fibroblasts. Because pulp cells and periodontal ligament (PDL) fibroblasts can express thrombin receptor mRNA, the specific aim of this study was to determine whether thrombin can activate the growth, attachment, protein synthesis, alkaline phosphatase activities and cellular clustering of cultured human PDL fibroblasts. Thrombin can stimulate the growth of PDL fibroblasts in a dose dependent manner (as analyzed by MTT assay). At concentrations of 5 and 10 U/ml, thrombin increased the cell numbers to 141% and 153% greater than that of the control after 5 days of incubation, respectively. Thrombin (5-20 U/ml) also stimulated the protein synthesis rate (assayed by [3H]proline incorporation) to 1.88-2.13 fold that of the control. However, pretreatment of PDL fibroblasts with thrombin (1-20 U/ml) could not promote the attachment of PDL fibroblasts to type I collagen and fibronectin. Moreover, thrombin could induce clustering of PDL fibroblasts within a concentration range of 5-20 U/ml. However, thrombin (1-20 U/ml) exerted neither stimulatory nor inhibitory effect on cellular alkaline phosphatase activities. In conclusion, it appears that the presence of thrombin seems to have effects on PDL fibroblasts in terms of cell growth, protein synthesis and cell clustering. This suggests that thrombin might be important in the early healing process of periodontium following periodontal surgery.

Areca nut extract inhibits the growth, attachment, and matrix protein synthesis of cultured human gingival fibroblasts

Betel quid chewing is a popular oral habit in India, South Africa, and many Southeast Asian countries. The effects of areca nut (AN) extract on the growth, attachment, and protein synthesis of healthy human gingival fibroblasts (GF) were investigated to determine why betel quid (BQ) chewers have higher prevalence of periodontal disease than non-chewers. Twenty-four hour exposure of human GF to AN extract (> 200 microg/ml) in culture led to the formation of numerous intracellular vacuoles. As analyzed by modified MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide] assay, AN extract significantly suppressed the growth of GF over 5 days of incubation in a dose-dependent manner. At concentrations of 50 and 300 microg/ml, AN extract suppressed the growth of GF with 30% and 57% (P < 0.05), respectively. AN extract also significantly suppressed the synthesis of [3H]proline incorporation into trichloroacetic acid (TCA) precipitated proteins. At concentrations of 200, 400, and 600 microg/ml, AN extract suppressed the protein synthesis with 33%, 58%, and 63% of inhibition (P < 0.05), respectively. Preincubation of cells in a medium containing AN extract for 2 hours inhibits the subsequent attachment of cultured GF to type I collagen at the 50% inhibitory concentration (IC50) which is about 720 to 798 microg/ml. Considering the frequent consumption of BQ throughout the day, impairment of sequential fibroblast functions by BQ ingredients is a potential mechanism through which BQ chewing exert a deleterious effect to the gingival tissues.

Manoalide, a phospholipase A2 inhibitor, inhibits arachidonate incorporation and turnover in brain phospholipids of the awake rat

The Fatty Acid method was used to determine whether incorporation of plasma radiolabeled arachidonic acid into brain phospholipids is controlled by phospholipase A2. Awake rats received an i.v. injection of a phospholipase A2 inhibitor, manoalide (10 mg/kg), and then were infused i.v. with [1-(14)C]arachidonate or [3H]arachidonate. Animals were killed after infusion by microwave irradiation, and tracer distribution was analyzed in brain phospholipid, neutral lipid and acyl-CoA pools. Calcium-independent phospholipase A2 activity in brain homogenate was reduced by manoalide, whereas phospholipase C activity was unaffected. At 60 min but not at 20 or 40 min after its injection, manoalide had significantly decreased by 50% incorporation of unesterified arachidonate into and turnover within brain phospholipids, taking into account dilution of the brain arachidonoyl-CoA pool by recycled arachidonate. Manoalide also increased by 100% the net rate of unesterified arachidonate incorporation into brain triacylglycerol. This study indicates that manoalide can be used to inhibit brain phospholipase A2 in vivo, and that phospholipase A2 plays a critical role in arachidonate turnover in brain phospholipids and neutral lipids.

Elevated arterial base deficit in trauma patients: a marker of impaired oxygen utilization

BACKGROUND

In trauma patients, the admission value of arterial base deficit stratifies injury severity, predicts complications, and is correlated with arterial lactate concentration. In theory, elevated base deficit and lactate concentrations after shock are related to oxygen transport imbalance at the cellular level. The purpose of this study was to test the hypothesis that an elevated base deficit in trauma patients is indicative of impaired systemic oxygen utilization and portends poor outcomes.

METHODS

This study was a retrospective analysis of a prospectively collected database. The study population included all patients admitted to the trauma intensive care unit at a Level 1 trauma center during a 12-month period who were monitored with a pulmonary artery catheter and serial measurements of lactate and base deficit, and who achieved a normal arterial lactate concentration (< 2.2 mmol/L) with resuscitation. The patients were divided into those who maintained a persistently high base deficit (> or = 4 mmol/L) and those who achieved a low base deficit (< 4 mmol/L) during resuscitation.

RESULTS

One-hundred patients (mortality 20%) were monitored with a pulmonary artery catheter and achieved a normal arterial lactate concentration. The mean age+/-SD (SEM) of the group was 37+/-17 years and the Injury Severity Score was 25+/-11. Subgroup analysis revealed that patients with a persistently high base deficit (n=26) had higher rates of multiple organ failure (35% versus 5%, p < 0.001) and death (50% versus 9%, p < 0.00001) compared with patients who achieved a low base deficit. Patients with a persistently high base deficit also had lower oxygen consumption (126+/-40 mL/m2 versus 156+/-30 mL/m2, p=0.01 at 48 hours) and a lower oxygen utilization coefficient (0.20+/-0.05 versus 0.24+/-0.03, p=0.01 at 48 hours) compared with patients with a low base deficit. At 48 hours, both oxygen consumption (r=-0.44, [r, correlation coefficient] p=0.002) and oxygen utilization (r=-0.46, p=0.001) had a significant negative correlation with base deficit.

CONCLUSIONS

In trauma patients, a persistently high arterial base deficit is associated with altered oxygen utilization and an increased risk of multiple organ failure and mortality. Serial monitoring of base deficit may be useful in assessing the adequacy of oxygen transport and resuscitation.

Cloning and sequence analysis of the Candida tropicalis URA3 gene encoding orotidine-5'-phosphate decarboxylase

An integrative transformation system was established for a phenol-utilizing strain of Candida tropicalis M4. The system is based on an auxotrophic mutant host of C. tropicalis U-6 that is defective in orotidine-5'-phosphate decarboxylase (ODCase). As a selectable marker, we isolated and characterized the C. tropicalis URA3 gene, which codes for ODCase. The gene was cloned by complementation of the ura3 mutation of Sachharomyces cerevisiae SHY-3 and the pyrF mutation of Escherichia coli. The C. tropicalis U-6 was transformed by plasmid containing the C. tropicalis URA3 gene at a frequency of 1 to 10 transformants per microgram of plasmid DNA. When the URA3 gene was expressed in E. coli minicells, a 30-kDa protein was identified. Nucleotide sequence analysis revealed the presence of an open reading frame, encoding a protein of 268 amino acids with a calculated molecular mass of 29.7 kDa. The nucleotide sequence of URA3 gene and its deduced amino acid sequence showed significant homology to those of the ODCase of other fungal species.