Cytotoxicity and immunogenicity of SACCHACHITIN and its mechanism of action on skin wound healing

SACCHACHITIN membrane, a weavable skin substitute made from the residual fruiting body of Ganoderma tsugae, has been demonstrated to promote skin wound healing. Prior to its clinical application, it is critical to learn more about any possible cytotoxicity, immunogenicity, or allergy response, and at least some of its mechanism(s) of action(s). In the present studies, it has been found that SACCHACHITIN suspension at less than 0.05% shows no cytotoxicity to the primary culture of rat fibroblasts. However, at higher concentrations (> or = 0.1%), it does reduce the growth of fibroblasts, based on MTT assays. This might be caused by positive charges on chitin molecules that are too strong, and may be harmful to the cell membrane. SACCHACHITIN showed no immunogenicity after it was inoculated into rats three times; however, the unmodified, purified rabbit type I and type II collagens did. Subcutaneous injection of SACCHACHITIN suspension into rats showed no gross allergic responses on skin. Nevertheless, it did cause local acute inflammation, as observed by histological investigation. This is similar to what occurred in the wound site covered with SACCHACHITIN membrane. The chemotactic effect of SACCHACHITIN was exhibited in both intact and wounded skin tissues. This may be one of the initial beneficial effects of SACCHACHITIN membrane to wound healing. The rapid acute inflammatory process was followed by the appearance of angiogenesis and granulation tissue formation, which occurred earlier than it normally would. Coverage of the wound area with SACCHACHITIN membrane also induced an earlier formation of scar tissue to replace the granulation tissue. A 1.5 x 1.5 cm(2) wound area covered by SACCHACHITIN completely healed by 21 days, while that covered with cotton gauze did not. Therefore, SACCHACHITIN is a safe biomaterial for use as a wound dressing for skin healing. Its promoting action for wound healing might be due to its chemotactic effect for inflammatory cells. This, in turn, may facilitate subsequent angiogenesis, granulation tissue formation, and faster new tissue formation, leading to faster wound healing.

In vitro dehalogenation of tetrachloroethylene (PCE) by cell-free extracts of Clostridium bifermentans DPH-1

Cell-free extracts of Clostridium bifermentans DPH-1 catalyzed tetrachloroethylene (PCE) dechlorination. PCE degradation was stimulated by addition of a variety of electron donors. Ethanol (0.61 mM) was the most effective electron donor for PCE dechlorination. Maximum activity was recorded at 30 degrees C and pH 7.5. Addition of NADH as a cofactor stimulated enzymatic activity but the activity was not stimulated by addition of metal ions. When the cell-free enzyme extract was incubated in the presence of titanium citrate as a reducing agent, the dehalogenase was rapidly inactivated by propyl iodide (0.5 mM). The activity of propyliodide-reacted enzyme was restored by illumination with a 250 W lamp. The dehalogenase activity was also inhibited by cyanide. The substrate spectrum of activity included trichloroethylene (TCE), cis-1,2-dichloroethylene (cDCE), trans-dichloroethylene, 1,1-dichloroethylene, 1,2-dichloroethane, and 1,1,2-trichloroethane. The highest rate of degradation of the chlorinated aliphatic compounds was achieved with PCE, and PCE was principally degraded via TCE to cDCE. Results indicate that the dehalogenase could play a vital role in the breakdown of PCE as well as a variety of other chlorinated aliphatic compounds.

[Effects of light intensity on the physiological parameters of the premature infant]

This study attempts to find out the effects of light intensity on premature infants' physiological parameters. The research method adopted utilized a quasiexperimental repeated measures design. Thirty-five premature infants born in no more than thirty seven gestation weeks and with birth weight less than 2500g were targeted. The first step was to examine the original arrangement of the blankets over the incubators, the second step was to investigate the effect of placing blankets on the top of the incubator and draped down the top 1/3 of the sides. The third step was conducted without blankets. Factors including light intensity and volume in the incubator and heart rate, respiration rate, and blood oxygen saturation of the premature infants were recorded in all three steps. During the experimental period, no nursing treatment or interventions were allowed. Instruments used in the study included a photometer, a phonometer, a V8 camera, a heart rate monitor, a respiration monitor, and a blood oxygen saturation monitor. The study was conducted in the NICUs in three district hospitals in northern Taiwan. To analyze the data, descriptive statistics and the General Estimation Equation (GEE) were applied. The study shows: (1) Light intensity had a significant statistical relationship with the premature infants' physiological parameters (p = .00). (2) The heart rate and respiration rate increased and the blood oxygen saturation decreased as the intensity of light went up. (3) Placing a blanket over the top and sides of the incubator effectively reduces light levels inside (p = .00). The results of this study suggest a treatment principle for premature infants and provide a basis further research.

Pentaketide melanin biosynthesis in Aspergillus fumigatus requires chain-length shortening of a heptaketide precursor

Chain lengths and cyclization patterns of microbial polyketides are generally determined by polyketide synthases alone. Fungal polyketide melanins are often derived from a pentaketide 1,8-dihydroxynaphthalene, and pentaketide synthases are used for synthesis of the upstream pentaketide precursor, 1,3,6,8-tetrahydroxynaphthalene (1,3,6,8-THN). However, Aspergillus fumigatus, a human fungal pathogen, uses a heptaketide synthase (Alb1p) to synthesize its conidial pigment through a pentaketide pathway similar to that which produces 1,8-dihydroxynaphthalene-melanin. In this study we demonstrate that a novel protein, Ayg1p, is involved in the formation of 1,3,6,8-THN by chain-length shortening of a heptaketide precursor in A. fumigatus. Deletion of the ayg1 gene prevented the accumulation of 1,3,6,8-THN suggesting the involvement of ayg1 in 1,3,6,8-THN production. Genetic analyses of double-gene deletants suggested that Ayg1p catalyzes a novel biosynthetic step downstream of Alb1p and upstream of Arp2p (1,3,6,8-THN reductase). Further genetic and biochemical analyses of the reconstituted strains carrying alb1, ayg1, or alb1 + ayg1 indicated that Ayg1p is essential for synthesis of 1,3,6,8-THN in addition to Alb1p. Cell-free enzyme assays, using the crude Ayg1p protein extract, revealed that Ayg1p enzymatically shortened the heptaketide product of Alb1p to 1,3,6,8-THN. Thus, the protein Ayg1p facilitates the participation of a heptaketide synthase in a pentaketide pathway via a novel polyketide-shortening mechanism in A. fumigatus.

Purification, cloning, and sequencing of an enzyme mediating the reductive dechlorination of tetrachloroethylene (PCE) from Clostridium bifermentans DPH-1

An enzyme mediating the reductive dechlorination of tetrachloroethylene (PCE) from cell-free extracts of Clostridium bifermentans DPH-1 was purified, cloned, and sequenced. The enzyme catalyzed the reductive dechlorination of PCE to cis-1,2-dichloroethylene via trichloroethylene, at a Vmax and Km of 73 nmol/mg protein and 12 microM, respectively. Maximal activity was recorded at 35 degrees C and pH 7.5. Enzymatic activity was independent of metal ions but was oxygen sensitive. A mixture of propyl iodide and titanium citrate caused a light-reversible inhibition of enzymatic activity suggesting the involvement of a corrinoid cofactor. The molecular mass of the native enzyme was estimated to be approximately 70 kDa. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption ionization-time of flight/mass spectrometry (MALDI-TOF/MS) revealed molecular masses of approximately 35 kDa and 35.7 kDa, respectively. A broad spectrum of chlorinated aliphatic compounds (PCE, trichloroethylene, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, 1,1-dichloroethylene, 1,2-dichloropropane, and 1,1,2-trichloroethane) was degraded. With degenerate primers designed from the N-terminal sequence (27 amino acid residues), a partial sequence (81 bp) of the encoding gene was amplified by polymerase chain reaction (PCR) and sequenced. Southern analysis of C. bifermentans genomic DNA using the PCR product as a probe revealed restriction fragment bands. A 5.0 kb ClaI fragment, harboring the relevant gene (designated pceC) was cloned (pDEHAL5) and the complete nucleotide sequence of pceC was determined. The gene showed homology mainly with microbial membrane proteins and no homology with any known dehalogenase, suggesting a distinct PCE dehalogenase.

Condensation by DNA looping facilitates transfer of large DNA molecules into mammalian cells

Experimental studies of complete mammalian genes and other genetic domains are impeded by the difficulty of introducing large DNA molecules into cells in culture. Previously we have shown that GST-Z2, a protein that contains three zinc fingers and a proline-rich multimerization domain from the polydactyl zinc finger protein RIP60 fused to glutathione S-transferase (GST), mediates DNA binding and looping in vitro. Atomic force microscopy showed that GST-Z2 is able to condense 130-150 kb bacterial artificial chromosomes (BACs) into protein-DNA complexes containing multiple DNA loops. Condensation of the DNA loops onto the Z2 protein-BAC DNA core complexes with cationic lipid resulted in particles that were readily transferred into multiple cell types in culture. Transfer of total genomic linear DNA containing amplified DHFR genes into DHFR(-) cells by GST-Z2 resulted in a 10-fold higher transformation rate than calcium phosphate co-precipitation. Chinese hamster ovarian cells transfected with a BAC containing the human TP53 gene locus expressed p53, showing native promoter elements are active after GST-Z2-mediated gene transfer. Because DNA condensation by GST-Z2 does not require the introduction of specific recognition sequences into the DNA substrate, condensation by the Z2 domain of RIP60 may be used in conjunction with a variety of other agents to provide a flexible and efficient non-viral platform for the delivery of large genes into mammalian cells.

Cytotoxicity and arecoline mechanisms in human gingival fibroblasts in vitro

Betel nut chewing, like cigarette smoking, is a popular oral habit which impinges on the daily lives of a population of approximately 200 million. People who chew betel nuts have a higher prevalence of periodontal diseases than those who do not. Many of the undesirable effects of betel nuts have been attributed to arecoline, a major component of the particular alkaloid in betel nuts. In this in vitro study, we have focused on the effects of arecoline and the role it could play in periodontal breakdown via its direct effects on human gingival fibroblasts. Human gingival fibroblasts were derived from three healthy individuals undergoing crown-lengthening procedures. We found that arecoline is cytotoxic to human gingival fibroblasts at a concentration higher than 50 micrograms/ml by depleting intracellular thiols and inhibiting mitochondrial activity (P < 0.05). In addition, the cells displayed a marked arrest at G2/M phase in a dose-dependent manner. Repeated and long-term exposure to arecoline could impair the gingival fibroblast functions. As they are cytotoxic, the use of betel nut products in conjunction with periodontal therapy may interfere with optimal healing and/or lead to further periodontal breakdown.

The second STE12 homologue of Cryptococcus neoformans is MATa-specific and plays an important role in virulence

Cryptococcus neoformans STE12alpha, a homologue of Saccharomyces cerevisiae STE12, exists only in MATalpha strains. We identified another STE12 homologue, STE12a, which is MATa specific. As in the case with Deltaste12alpha, the mating efficiency for Deltaste12a was reduced significantly. The Deltaste12a strains surprisingly still mated with Deltaste12alpha strains. In MATalpha strains, STE12a functionally complemented STE12alpha for mating efficacy, haploid fruiting, and regulation of capsule size in the mouse brain. Furthermore, when STE12a was replaced with two copies of STE12alpha, the resulting MATa strain produced hyphae on filament agar. STE12a regulates mRNA levels of several genes that are important for virulence including CNLAC1 and CAP genes. STE12a also modulates enzyme activities of phospholipase and superoxide dismutase. Importantly, deletion of STE12a markedly reduced the virulence in mice, as is the case with STE12alpha. Brain smears of mice infected with the Deltaste12a strain showed yeast cells with a considerable reduction in capsule size compared with those infected with STE12a strains. When the disrupted locus of ste12a was replaced with a wild-type STE12a gene, both in vivo and in vitro mutant phenotypes were reversed. These results suggest that STE12a and STE12alpha have similar functions, and that the mating type of the cells influences the alleles to exert their biological effects. C. neoformans, thus, is the first fungal species that contains a mating-type-specific STE12 homologue in each mating type. Our results demonstrate that mating-type-specific genes are not only important for saprobic reproduction but also play an important role for survival of the organism in host tissue.

Adverse effects of arecoline and nicotine on human periodontal ligament fibroblasts in vitro

BACKGROUND, AIMS

The habit of betel nut chewing impinges on the daily lives of approximately 200 million people. Betel quid chewers have a higher prevalence of periodontal diseases than non-chewers. This study examined the pathobiological effects of arecoline, a major component of the betel nut alkaloids, on human periodontal ligament fibroblasts (PDLF) in vitro.

METHOD

Cell viability, proliferation, protein synthesis, and cellular thiol levels were used to investigate the effects of human PDLF exposed to arecoline levels of 0 to 200 microg/ml. In addition, nicotine was added to test how it modulated the effects of arecoline.

RESULTS

Arecoline significantly inhibited cell proliferation in a dose-dependent manner. At concentrations of 10 and 30 microg/ml, arecoline suppressed the growth of PDLF by 20% and 50% (p < 0.05), respectively. Arecoline also decreased protein synthesis in a dose-dependent manner during a 24-h culture period. A 100 microg/ ml concentration level of arecoline significantly inhibited protein synthesis to only 50% of that in the untreated control (p < 0.05). Moreover, arecoline significantly depleted intracellular thiols in a dose-dependent manner. At concentrations of 25 microg/ml and 100 microg/ml, arecoline depleted about 18% and 56% of thiols (p < 0.05), respectively. This suggests that arecoline itself might augment the destruction of periodontium associated with betel nut use. Furthermore, the addition of nicotine acted with a synergistic effect on the arecoline-induced cytotoxicity. At a concentration of 60 microg/ml, arecoline suppressed the growth of PDLF by about 33% and 5 mM nicotine enhanced the arecoline-induced cytotoxic response to cause about 66% cell death.

CONCLUSION

During thiol depletion, arecoline may render human PDLF more vulnerable to reactive agents within cigarettes. Taken together, people who combine habits of betel nut chewing with cigarette smoking could be more susceptible to periodontium damage than betel nut chewing alone.

Video-assisted thoracoscopic surgery for the diagnosis of patients with hilar and mediastinal lymphadenopathy

In areas where tuberculosis (TB) is rare, cases of hilar and mediastinal lymphadenopathy are often attributed to the diagnosis of sarcoidosis or a malignant process. However, these manifestations have been only sparsely reported in countries with high rates of TB. The role of simultaneous lung biopsy in the differential diagnosis of these patients using a thoracoscopic approach is also undetermined. In this prospective study, 15 adult patients with hilar and mediastinal lymphadenopathy were evaluated using video-assisted thoracoscopy during the period from May 1995 through September 1999. Biopsy of the hilar and mediastinal lymph nodes was undertaken in all 15 patients, and a wedge biopsy of the lungs was performed whenever frozen section of the nodes disclosed granulomatous inflammation. The final diagnoses included sarcoidosis (10 patients), TB (2), metastatic small cell carcinoma (2), and reactive lymphoid hyperplasia (1). No morbidity or mortality was associated with the operation. In patients with sarcoidosis and TB, most of the lymph node biopsy specimens disclosed extensive hyaline fibrosis. Lung biopsy specimens presented small non-necrotizing granulomas with multinucleated giant cells even in the absence of demonstrable parenchymal lesions. In the two patients with TB, identification of acid-fast bacilli and growth of Mycobacterium tuberculosis occurred only in lung specimens and not in specimens from lymph nodes. Video-assisted thoracoscopic surgery is a safe, simple, and effective procedure for the diagnosis of patients with hilar and mediastinal lymphadenopathy. Our results suggest that for a better differentiation between TB and sarcoidosis, an additional lung biopsy could be undertaken to provide specimens for microscopic examination and culture.

Isolation and characterization of antioxidant compounds from Aspergillus candidus broth filtrate

The objectives of this study were to isolate the antioxidative components in the broth filtrate of Aspergillus candidus (CCRC 31543), to characterize their antioxidative properties, and to evaluate their safety. Three major compounds were isolated and identified as 3,3' '-dihydroxyterphenyllin, 3-hydroxyterphenyllin, and candidusin B. In the linoleic acid peroxidation system, the inhibition of peroxidation in these three compounds was greater than 95% and was significantly higher than that of alpha-tocopherol but equal to that of BHA at 12.5-200 microg/mL. As measured using the Rancimat method in lard, 3,3' '-di-OH-terphenyllin exhibited a protection factor value of 7.82, which was substantially higher than those of BHA (5.58) and alpha-tocopherol (4.29) at 200 microg/mL. 3,3' '-di-OH-terphenyllin and 3-OH-terphenyllin also exhibited marked scavenging effects on the alpha,alpha-diphenyl-beta-picrylhydrazyl radicals (94.7 and 96.0%, respectively), which were similar to those of BHA and alpha-tocopherol. Safety studies showed that these three compounds were neither cyto- nor geno-toxic toward human intestine 407 (INT 407) cells, nor mutagenic toward Salmonella typhimurium TA98 and TA100.

Cytotoxicity of halothane on human gingival fibroblast cultures in vitro

Recently halothane has been reported to be the most suitable alternative to chloroform in dissolving gutta-percha. Periapical tissue toxicity of halothane is not completely known. In this study gutta-percha dissolved by halothane was evaluated with the almar blue dye assay using human gingival fibroblast cultures. The cytotoxic effects of halothane on human gingival fibroblasts depended on the exposure dose, frequency, and duration. A reduced concentration and smaller amount of gutta-percha solvents may minimize the cytotoxic effects on host tissues.

Differences in 99mTc-HMPAO brain SPET perfusion imaging between Tourette's syndrome and chronic tic disorder in children

Early differential diagnosis between Tourette's syndrome and chronic tic disorder is difficult but important because both the outcome and the treatment of these two childhood-onset diseases are distinct. We assessed the sensitivity and specificity of brain single-photon emission tomography (SPET) perfusion imaging in distinguishing the two diseases, and characterized their different cerebral perfusion patterns. Twenty-seven children with Tourette's syndrome and 11 with chronic tic disorder (mean age 9.5 and 8.6 years, respectively) underwent brain SPET with technetium-99m hexamethylpropylene amine oxime (HMPAO). Visual interpretation and semiquantitative analysis of SPET images were performed. On visual interpretation, 22 of 27 (82%) of the Tourette's syndrome group had lesions characterized by decreased perfusion. The left hemisphere was more frequently involved. None of the children with chronic tic disorder had a visible abnormality. Semi-quantitative analysis showed that, compared with children with chronic tic disorder, children with Tourette's syndrome had significantly lower perfusion in the left lateral temporal area and asymmetric perfusion in the dorsolateral frontal, lateral and medial temporal areas. In conclusion, using the visual approach, brain SPET perfusion imaging is sensitive and specific in differentiating Tourette's syndrome and chronic tic disorder. The perfusion difference between the two groups, demonstrated by semi-quantitative analysis, may be related more to the co-morbidity in Tourette's syndrome than to tics per se.

Cooperation of E2F-p130 and Sp1-pRb complexes in repression of the Chinese hamster dhfr gene

In mammalian cells reiterated binding sites for Sp1 and two overlapping and inverted E2F sites at the transcription start site regulate the dhfr promoter during the cell growth cycle. Here we have examined the contributions of the dhfr Sp1 and E2F sites in the repression of dhfr gene expression. In serum-starved cells or during serum stimulation, the Chinese hamster dhfr gene was not derepressed by trichostatin A (TSA), an inhibitor of histone deacetylases (HDAC). Immunoprecipitation experiments showed that HDAC1 and hypophosphorylated retinoblastoma protein (pRb) are associated with Sp1 in serum-starved CHOC400 cells. In transfection experiments, reporter plasmids containing the reiterated dhfr Sp1 sites were stimulated 10-fold by TSA, while a promoter containing four dhfr E2F sites and a TATA box was responsive to E2F but was completely unaffected by TSA. HDAC1 did not coprecipitate with p130-E2F DNA binding complexes, the predominant E2F binding activity in cell extracts after serum starvation, suggesting that p130 imposes a TSA-insensitive state on the dhfr promoter. In support of this notion, recruitment of GAL4-p130 to a dihydrofolate reductase-GAL4 reporter rendered the promoter insensitive to TSA, while repression by GAL4-pRb was sensitive to TSA. Upon phosphorylation of pRb and p130 after serum stimulation, the Sp1-pRb and p130-E2F interactions were lost while the Sp1-HDAC1 interaction persisted into S phase. Together these studies suggest a dynamic model for the cooperation of pRb and p130 in repression of dhfr gene expression during withdrawal from the cell cycle. We propose that, during initial phases of cell cycle withdrawal, the binding of dephosphorylated pRb to Sp1-HDAC1 complexes and complexes of E2F-1 -to -3 with DP results in transient, HDAC-dependent suppression of dhfr transcription. Upon withdrawal of cells into G(0), recruitment of p130 to E2F-4-DP-1 complexes at the transcription start site results in a TSA-insensitive complex that cooperates with Sp1-HDAC-pRb complexes to stably repress dhfr promoter activity in quiescent cells.

Cytotoxicity of fluoride on human pulp cell cultures in vitro

OBJECTIVES

Numerous studies have revealed that conventional glass-ionomer cements might release fluoride into an aqueous environment. The objective of this study was to examine the effects of fluoride on human pulp cells in vitro.

STUDY DESIGN

H33258 fluorescence, cell proliferation, protein synthesis, and mitochondrial activity assay were used to investigate the pathobiological effects of fluoride on cultured human pulp cells.

RESULTS

Fluoride was found to be a cytotoxic agent to cultured human pulp cells by inhibiting cell growth, proliferation, mitochondrial activity, and protein synthesis.

CONCLUSIONS

Fluoride release has significant potential for pulpal toxicity.

Value of chest sonography in the diagnosis and management of acute chest disease

PURPOSE

The aim of this study was to investigate the value of chest sonography in the diagnosis and management of patients with chest radiograph opacities in an emergency department.

METHODS

Seventy-eight patients with acute chest complaints whose chest radiographs showed opacities underwent chest sonography. The initial diagnosis (based on clinical manifestations and the chest radiograph), the sonographic diagnosis (before any invasive procedures), and the final diagnosis were compared. The impact of chest sonography on the management of patients with chest opacities was also analyzed.

RESULTS

The initial diagnosis was in concordance with the final diagnosis in 60 (77%) of the 78 patients, while the sonographic diagnosis was in concordance with the final diagnosis in 75 (96%) of the patients. Chest sonography therefore significantly increased the rate of correct diagnoses from 77% (95% confidence interval, 67-87%) to 96% (95% confidence interval, 92-100%; p < 0.0001). Sonography provided new information in 52 patients (67%): a different diagnosis from the initial diagnosis in 18 patients and additional diagnostic information in 34 patients. New information gained from sonography affected the management of 35 patients. Sonography also provided help in guiding 42 (70%) of 60 invasive diagnostic procedures and 22 (73%) of 30 invasive therapeutic procedures for which chest radiography and physical examination had failed to or were unsuitable to provide guidance. Overall, sonography assisted in the management of 64 (82%) of 78 patients. Sonography was of no benefit in 14 patients (18%).

CONCLUSIONS

We conclude that chest sonography can complement chest radiography and is of value in the diagnosis and management of emergency department patients with acute chest diseases presenting as opacities on chest radiographs.

Cardiac beriberi among illegal mainland Chinese immigrants

The most common symptoms of chronic beriberi due to thiamine deficiency include dyspnoea, fatigue, leg oedema, lower extremity weakness and numbness. When collapsed peripheral circulation, metabolic acidosis, or shock are present, the disease has advanced from chronic beriberi to pernicious or fulminating beriberi heart failure (Shoshin beriberi). We report two patients with fulminating beriberi; both of whom had been incarcerated at a detention centre for 5 months before hospitalization. A prolonged monotonous diet, low in thiamine, was a major risk factor in both patients. Thiamine deficiency should be considered for any patient with symptoms and signs compatible with beriberi.

Hepatic angiomyolipoma with concomitant hepatocellular carcinomas

Angiomyolipoma is a rare lipomatous tumor in the liver. Definitive preoperative diagnosis is becoming easier by the use of ultrasonography, computed tomography, and magnetic resonance imaging techniques. Nonsurgical treatment has been advocated for its benign nature. However, recently we encountered one case of hepatic angiomyolipoma with two concomitant hepatocellular carcinomas on a hepatitis B carrier. Although his serum alpha-fetoprotein was normal, under the above impression these lesions were resected. The pathologic findings showed a typical angiomyolipoma and two well-differentiated hepatocellular carcinomas with marked fatty metamorphosis. This is the first report of angiomyolipoma with concomitant hepatocellular carcinomas in the literature. Nonsurgical treatment of angiomyolipoma in an endemic area for hepatocellular carcinoma should proceed with caution because cases of fat-rich minute hepatocellular carcinomas will make the diagnosis difficult.

Acute flaccid paralysis in infants and young children with enterovirus 71 infection: MR imaging findings and clinical correlates

BACKGROUND AND PURPOSE

Enterovirus 71 (EV71) infection is now considered an important cause of childhood acute flaccid paralysis. The purpose of our study was to determine whether EV71-infection-related acute flaccid paralysis in infants and young children has characteristic MR imaging patterns.

METHODS

Seven infants and young children with acute paralysis of the upper or lower extremities and positive EV71 cultures underwent spinal MR studies during an outbreak of hand-foot-and-mouth disease in Taiwan in 1998.

RESULTS

Acute paralysis was observed in one upper extremity in two patients, in one lower extremity in three patients, and in both lower extremities in two patients. None of the patients had sensory impairment or bulbar palsy. MR studies showed unilateral or bilateral hyperintense lesions in the anterior horn regions of the cord on T2-weighted images in six patients. No abnormal signal was present in one patient. Two of three patients who received intravenous injections of contrast material had ventral root enhancement on T1-weighted images. One of them also had enhancement of the unilateral anterior horn cells. At clinical follow-up, both patients with bilateral anterior horn abnormalities had residual motor weakness, whereas only one of the five patients with unilateral involvement had residual weakness.

CONCLUSION

EV71 radiculomyelitis tends to be unilateral and to specifically involve both the anterior horn cells of the cord and the ventral roots. MR imaging allows early detection of spinal cord and root lesions.

Synergistic effects of peroxynitrite on arecoline-induced cytotoxicity in human buccal mucosal fibroblasts

Epidemiological studies have demonstrated a clear association between betel nut chewing and an increased risk for oral mucosal lesions. Arecoline, the most abundant betel alkaloid, is considered the most important etiologic factor in betel nuts. In addition, most betel nut chewers are also smokers. In order to elucidate the potential toxicological implications of interactions of arecoline and peroxynitrite (a reaction product of cigarette smoking), cell viability, and cellular levels of glutathione (GSH) were investigated, using cultured human buccal mucosal fibroblasts. At a concentration higher than 0.8 mM, arecoline was cytotoxic to buccal mucosal fibroblasts in a concentration- and time-dependent manner. Arecoline also depleted intracellular GSH in a dose-dependent manner (P<0.05). The addition of extracellular peroxynitrite acted as a synergistic effect on the arecoline-induced cytotoxicity (P<0.05). Furthermore, at a concentration of 0.8 mM, arecoline depleted intracellular GSH by about 42%, while 2 mM peroxynitrite enhanced the arecoline-depleted GSH level further to 86% as compared with the control. During GSH depletion, arecoline may render the human buccal mucosal fibroblasts more vulnerable to other reactive agents within cigarette smoking. Taken together, we suggest that people who combine the habits of betel nut chewing with cigarette smoking could be more susceptible to oral mucosal damage than betel quid chewing alone.

Butachlor, a suspected carcinogen, alters growth and transformation characteristics of mouse liver cells

Butachlor is a widely used herbicide in Asia and South America. Previous investigations have indicated that it is a suspected carcinogen. To understand more about the biological effects of butachlor on cultured cells and the mechanism(s) of its carcinogenicity, we studied the alteration of the growth characteristics that was induced by butachlor in normal mouse liver cells (BNL CL2). This study demonstrates that butachlor decreases the population-doubling time of BNL CL2 cells, suggesting that it stimulates cell proliferation. To support this finding, a thymidine incorporation assay was conducted and a similar result that butachlor stimulates cell proliferation was elucidated. In addition, we show that butachlor increases the saturation density of the BNL CL2 cells. When combined with the tumor initiator N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), butachlor transforms cells efficiently, as demonstrated by loss of contact inhibition. These findings indicate that butachlor alters the growth characteristics of BNL CL2 cells and suggest that butachlor may induce malignant transformation through stimulation of cell proliferation, alteration of cell cycle regulation, and suppression of cell density-dependent inhibition of proliferation.

Aspergillus fumigatus alb1 encodes naphthopyrone synthase when expressed in Aspergillus oryzae

Conidial pigment biosynthesis is an important virulence factor in Aspergillus fumigatus, a human fungal pathogen. Involvement of DHN-melanin pathway in the biosynthesis of A. fumigatus conidial pigment implies that the Alb1p polyketide synthase (PKS) is a 1,3,6, 8-tetrahydroxynaphthalene (T4HN) synthase. The Alb1p, however, shows higher sequence similarity to a naphthopyrone synthase than to a T4HN synthase. To clarify the function of Alb1p, the alb1 gene was overexpressed in a heterologous host Aspergillus oryzae. The Alb1p PKS product in this heterologous expression system was identified as heptaketide naphthopyrone instead of pentaketide T4HN. The data suggest that Alb1p is a naphthopyrone synthase.

A simple self-rating assessment method of residual work capability for occupational permanent disabilities

BACKGROUND

To explore the validity, reliability, and determinants of a simple self-rating assessment method of residual work capability (RWC) after occupational permanent disabilities.

METHODS

Five hundred and thirty-nine compensated permanent disability workers answered three consecutive visual analogue questionnaires wherein they self-rated their residual work capability in terms of speed (RWCS), quality (RWCQ) and a combination of speed and quality (RWCC). At two major hospitals in Taiwan, 169 of these subjects were evaluated with physical capacity assessment (PCA), cognition and sensation assessment (CSA), the work ability index (WAI), and the 12-item Chinese health questionnaire (CHQ-12).

RESULTS

High test-retest reliability (Pearson's correlation coefficient 0.77) and satisfactory concurrent validity were shown for RWCS and RWCC. All PCA, CSA and WAI showed significant correlation with RWCs, while CHQ-12 displayed borderline correlation. Employment status after injury and status of the victim's salary as the main source of income for his/her family before injury, were the major determinants of RWCs, in addition to the scales of PCA, CSA and WAI.

CONCLUSIONS

The RWCC resulting from the self-rating method may be used as a simple assessment of a victim's residual work capability after occupational permanent disabilities.

Characterization of the distal tail fiber locus and determination of the receptor for phage AR1, which specifically infects Escherichia coli O157:H7

Phage AR1 is similar to phage T4 in several essential genes but differs in host range. AR1 infects various isolates of Escherichia coli O157:H7 but does not infect K-12 strains that are commonly infected by T4. We report here the determinants that confer this infection specificity. In T-even phages, gp37 and gp38 are components of the tail fiber that are critical for phage-host interaction. The counterparts in AR1 may be similarly important and, therefore, were characterized. The AR1 gp37 has a sequence that differs totally from those of T2 and T4, except for a short stretch at the N terminus. The gp38 sequence, however, has some conservation between AR1 and T2 but not between AR1 and T4. The sequences that are most closely related to the AR1 gp37 and gp38 are those of phage Ac3 in the T2 family. To identify the AR1-specific receptor, E. coli O157:H7 was mutated by Tn10 insertion and selected for an AR1-resistant phenotype. A mutant so obtained has an insertion occurring at ompC that encodes an outer membrane porin. To confirm the role of OmpC in the AR1 infection, homologous replacement was used to create an ompC disruption mutant (RM). When RM was complemented with OmpC originated from an O157:H7 strain, but not from K-12, its AR1 susceptibility was fully restored. Our results suggest that the host specificity of AR1 is mediated at least in part through the OmpC molecule.