Clinical Outcomes of Metastatic Breast Cancer in Patients Having Imaging Liver Pseudocirrhosis with or without Evident Varices

BACKGROUND

Pseudocirrhosis is an imaging finding of malignancies with liver metastasis with or without clinical liver cirrhosis-related portal hypertension (pHTN). This study defined evident pHTN by the presence of esophageal or gastric varices and compared patients' outcomes of metastatic breast cancer with imaging-diagnosed pseudocirrhosis with or without varices.

METHODS

The medical records from patients with metastatic breast cancer and pseudocirrhosis between 2005 and 2017 were retrospectively analyzed. Survival outcomes were compared based on endoscopic evidence of esophageal or gastric varices.

RESULTS

Among 106 patients with pseudocirrhosis, 33 (31%) had de novo stage IV disease, and 66 (62%) had hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer. Eighty-one (76%) had initial metastases in both hepatic lobes, and 32 (30%) had esophageal or gastric varices. The median overall survival (OS) was 5 and 13 months in patients with and without varices (P = .002). The median OS in patients with HER2-positive, HR-positive/HER2-negative, and triple-negative subtype was 16, 9, and 2 months, respectively (P = .001). Patients with varices usually had cirrhotic complications, including gastrointestinal bleeding, hyperbilirubinemia, hyperammonemia, and coagulopathy. Despite their challenging clinical conditions, 7 patients with varices had OS exceeding 1 year. In multivariate analysis, evident varices (P = .007) and triple-negative subtype (P = .013) were associated with poor OS.

CONCLUSIONS

Patients with pseudocirrhosis and evident varices had a significantly shorter median OS, and were usually associated with clinical cirrhosis-related complications. To maximize OS, early identification and meticulous supportive care are warranted.

[Progress of lupus anticoagulant detection in venous thromboembolism]

Lupus anticoagulant is one of the risk factors for venous thromboembolism, and the detection of lupus anticoagulant in patients with venous thromboembolism is important for the choice of treatment options and prognosis of treatment. There was no relevant literature to analyze and summarize the application progress of lupus anticoagulant detection in venous thromboembolism. In order to deepen the understanding of such patients, and help clinicians to conduct reasonable diagnosis, treatment and management of these patients, we reviewed the relevant epidemiology, test precautions, and the value of test results in venous thromboembolism and related treatments.

Screening for fear of cancer recurrence: Instrument validation and current status in early stage lung cancer patients

BACKGROUND

Fear of cancer recurrence (FCR) is one of the most distressing concerns for cancer patients. A psychometrically validated brief scale is urgently needed for use in busy clinical oncology settings. This study aimed to (1) develop and validate the 7-item fear of cancer recurrence scale Chinese version (FCR7-C), and (2) explore the severity of FCR in post-operative early-stage lung cancer patients in Taiwan.

METHODS

Early-stage lung cancer patients were recruited from a medical center in Taiwan. The FCR7-C was evaluated for content and construct validity and internal consistency reliability. Construct validity of FCR7-C was determined by the empirically supported correlation and confirmatory factor analysis (CFA).

RESULTS

A total of 160 subjects were recruited. The FCR7-C was shown to have satisfactory content validity and internal consistency reliability (Cronbach's α = 0.9). The uni-dimensional structure was confirmed by CFA that showed a good fit for the model. The FCR7-C score correlates positively with the degree of most of the physical symptoms, anxiety, and depression, but correlates negatively with patient age, performance status, and quality of life. We found that 81.9% of patients reported at least some FCR, with a mean FCR severity of 15.18 (SD = 7.78).

CONCLUSION

FCR7-C is a brief screening tool with good psychometrics. Patients with early-stage lung cancer still revealed mild to moderate level of FCR. Applying the FCR7-C for to screen cancer patients' distress and further develop personalized psychological interventions would be strongly suggested.

Historical epidemiology of hepatitis C virus in select countries-volume 4

Due to the introduction of newer, more efficacious treatment options, there is a pressing need for policy makers and public health officials to develop or adapt national hepatitis C virus (HCV) control strategies to the changing epidemiological landscape. To do so, detailed, country-specific data are needed to characterize the burden of chronic HCV infection. In this study of 17 countries, a literature review of published and unpublished data on HCV prevalence, viraemia, genotype, age and gender distribution, liver transplants and diagnosis and treatment rates was conducted, and inputs were validated by expert consensus in each country. Viraemic prevalence in this study ranged from 0.2% in Hong Kong to 2.4% in Taiwan, while the largest viraemic populations were in Nigeria (2 597 000 cases) and Taiwan (569 000 cases). Diagnosis, treatment and liver transplant rates varied widely across the countries included in this analysis, as did the availability of reliable data. Addressing data gaps will be critical for the development of future strategies to manage and minimize the disease burden of hepatitis C.

The present and future disease burden of hepatitis C virus infections with today's treatment paradigm: Volume 4

Factors influencing the morbidity and mortality associated with viremic hepatitis C virus (HCV) infection change over time and place, making it difficult to compare reported estimates. Models were developed for 17 countries (Bahrain, Bulgaria, Cameroon, Colombia, Croatia, Dominican Republic, Ethiopia, Ghana, Hong Kong, Jordan, Kazakhstan, Malaysia, Morocco, Nigeria, Qatar and Taiwan) to quantify and characterize the viremic population as well as forecast the changes in the infected population and the corresponding disease burden from 2015 to 2030. Model inputs were agreed upon through expert consensus, and a standardized methodology was followed to allow for comparison across countries. The viremic prevalence is expected to remain constant or decline in all but four countries (Ethiopia, Ghana, Jordan and Oman); however, HCV-related morbidity and mortality will increase in all countries except Qatar and Taiwan. In Qatar, the high-treatment rate will contribute to a reduction in total cases and HCV-related morbidity by 2030. In the remaining countries, however, the current treatment paradigm will be insufficient to achieve large reductions in HCV-related morbidity and mortality.

Strategies to manage hepatitis C virus infection disease burden-Volume 4

The hepatitis C virus (HCV) epidemic was forecasted through 2030 for 17 countries in Africa, Asia, Europe, Latin America and the Middle East, and interventions for achieving the Global Health Sector Strategy on viral hepatitis targets-"WHO Targets" (65% reduction in HCV-related deaths, 90% reduction in new infections and 90% of infections diagnosed by 2030) were considered. Scaling up treatment and diagnosis rates over time would be required to achieve these targets in all but one country, even with the introduction of high SVR therapies. The scenarios developed to achieve the WHO Targets in all countries studied assumed the implementation of national policies to prevent new infections and to diagnose current infections through screening.

[Reducing maternal parenting stress of children with autism spectrum disorder: father's involvement]

Objective: To explore the relationship between fathers' nursing time and maternal parenting stress of children with autism spectrum disorder(ASD). Method: Mothers of 98 ASD children who were first diagnosed in the department of Child Health Care, Children's Hospital of Fudan University during June 2015 to January 2016 were included in the ASD group, with mothers of 92 typical children from a Community Maternal and Child Health Hospital and a kindergarten in the control group. The evaluation of parenting stress, parents' nursing time and other related factors were cross-sectionally analyzed. Interview was conducted with the following tools: Parental Stress Index-Short Form(PSI-SF)for maternal parenting stress, and self-made General Parenting Information Questionnaire for nursing time of both parents and other related factors. The relationships were analyzed by Multiple Linear Regression analysis and Wilcoxon Rank-Sum test. Result: Maternal parenting stress of ASD children had a significant negative correlation with father's nursing time in total score of parenting stress, PCDI domain and PD domain (t=-2.76, -2.98, -2.79; P=0.007, 0.004, 0.006), within which PD domain also included family annual income and mothers' nursing time (R(2)=0.22, 0.24, 0.25); while no such correlation was found in control group in terms of father's nursing time(P=0.22, 0.42, 0.06). Wilcoxon Rank-Sum test showed that in 62 (63.3%) double-income ASD families and 72(78.3%) double-income typical families, there were significant differences between ASD fathers' and ASD mothers'and typical fathers'nursing time(2.0(0.5, 2.1)vs. 3.5(2.4, 6.0)vs. 3.0(2.0, 4.7)h, t=-86.32、-49.65, all P<0.01). Conclusion: Lack of fathers' involvements was common in ASD children's families. Increasing these fathers' nursing time, as well as their enthusiasm and initiative in the family intervention could relieve maternal parenting stress and improve the intervention pattern of ASD children.

An open-label, single-arm pilot study in patients with severe plaque-type psoriasis treated with an oral anti-inflammatory agent, apremilast

OBJECTIVE

To evaluate the clinical and biological activity of apremilast in patients with severe plaque-type psoriasis.

RESEARCH DESIGN AND METHODS

Apremilast, a phosphodiesterase-4 inhibitor, inhibits in vitro activity of multiple inflammatory factors implicated in the pathogenesis of psoriasis. Patients received 20 mg apremilast orally for 29 days. Immunohistological analysis was conducted on lesional-skin biopsies for psoriasis-associated inflammatory markers. Lipopolysaccharide-stimulated tumor necrosis factor-alpha levels were evaluated in blood. Psoriasis Area and Severity Index (PASI), static Physician's Global Assessment, and Body Surface Area were used to monitor disease severity.

RESULTS

There were 19 patients enrolled in this study, of whom 17 completed the study. Epidermal thickness was reduced by a mean of 20.5% from baseline to day 29. Among the responders, T cells were reduced by 28.8% and 42.6% in the dermis and epidermis, respectively. Similarly, CD11c cells were reduced by 18.5% and 40.2% in the dermis and epidermis, respectively. Fourteen of the 19 (73.7%) patients demonstrated an improvement in their PASI scores.

LIMITATIONS

This was a small, single-arm, open-label pilot study; therefore there was neither a placebo nor a comparison group.

CONCLUSION

Apremilast demonstrated biological activity and improved psoriasis clinical efficacy scores in patients with severe plaque-type psoriasis. The majority of adverse events were mild in nature. Two adverse events (fatigue and dizziness) were judged by the investigator to be moderate and related to apremilast. In addition, there were no clinically-relevant abnormal laboratory test results in subjects treated with apremilast for 29 days.

Treatments of oil-refinery and steel-mill wastewaters by mesocosm constructed wetland systems

In this study, two types of industrial wastewater, oil-refining and steel-milling, were selected for investigating their feasibility of treatment by mesocosm constructed wetland systems. The secondly treated effluents from the wastewater treatment plants were directly discharged into the systems controlled at different flow rates. Three wetland mesocosms were installed in the two industries: mesocosms A and B were in the oil refinery, and mesocosm C was in the steel mill. The substratum media used in wetland systems were sand (mesocosm A) and gravel (mesocosms B and C), while the vegetation types selected were reeds (mesocosms A and B) and mixed species of reeds and cattails (mesocosm C). The flow regimes were controlled as free water surface (FWS) and subsurface flow (SSF) for the sand- and gravel-beds, respectively. According to the experimental results, we found that the system treating oil-refining wastewater performed better than that treating steel-milling wastewater learned by comparing the removal efficiencies of COD, total N and total P. In addition, it was found that for oil-refining wastewater treatments, the SSF wetland system (mesocosm B) performed better than FWS (mesocosm A) wetland system when comparing both of their removal of pollutants and growth of vegetation. Besides, the effluents from these two industrial wetland treatment systems might be reclaimed and reused for boiler water, cooling, cleaning and miscellaneous purposes in industries. Further treatments are required if the constructed wetland effluents are thought about being reused for processing in industries.

Pig amelogenin gene expresses a unique exon 4

The pig amelogenin gene was isolated from a Lambda genomic library, and a 6.3 kb SalI/XbaI restriction fragment, inclusive of exons 3 through 7, was subcloned into a plasmid vector. DNA sequencing revealed two putative exon 4 sequences. The derived amino acid sequence of exon 4a, KSGRWGARLTAFVSSVQ, had previously been identified in a 190-amino-acid amelogenin isoform by protein sequencing. Exon 4b encoded the peptide DLYLEAIRIDRTAF, which is homologous to exon 4-encoded segments reported for human, mouse, and rat. Oligonucleotides from both of these exons were used to amplify cDNA generated from developing teeth. Amplification products were analyzed by agarose gel electrophoresis, cloned, and characterized by DNA sequencing. Exon 4a was found in transcripts encoding amelogenin isoforms having 190 and 73 amino acids. Exon 4b was found only in apparent splicing intermediates that retained intron 3, but was not detected in any final mRNA transcripts. Pig amelogenin having apparent molecular mass of 23 kD were isolated from the enamel matrix and characterized by mass spectrometry. Two mass values, 18,512.5, and 18,571.2 Da, were measured that match the values predicted for the 162-amino-acid cleavage product of the 173-amino-acid amelogenin, and the 165-amino-acid cleavage product of the 190-amino-acid amelogenin, which includes 17 amino acids encoded by exon 4a. We conclude that the pig amelogenin gene expresses a unique exon 4 that is not homologous to, or evolved from, the exon 4 segment expressed in humans and rodents.

Calcium binding of enamel proteins and their derivatives with emphasis on the calcium-binding domain of porcine sheathlin

Dental enamel is believed to form by the transfer of ions from solution, primarily calcium, phosphate, hydroxyl and carbonate, to the surface of solid-state mineral. Such precipitation phenomena can be controlled by regulating the degree of saturation of the solution with respect to the potential solid phases that can form. The concentration of free calcium is the factor that most affects the degree of saturation for calcium hydroxyapatite, and its buffering by calcium-binding proteins has been proposed as the mechanism that determines the enamel mineral structure. In this study, Stains-all staining was used to identify and isolate calcium-binding proteins from the enamel matrix, and determine their structures and association constants for calcium. Proteolytic cleavage fragments derived from the C-terminus of sheathlin, having apparent molecular weights of 13, 15, 27 and 29 kDa, were characterized by amino-terminal protein sequencing, amino acid analysis, and sugar, phosphate and sulphate determinations. Sheathlin C-terminal cleavage products were shown to have no N-linked glycosylations or phosphorylated amino acids, but Pro(350) was hydroxylated, and there was one sulphated O-linked glycosylation at Thr(386), containing galactose and N-acetylgalactosamine. The calcium-binding association constants for enamel proteins ranged from a high of 1.2 x 10(4) M(-1) to a low of 4.4x10(1) M(-1). The relative strengths of binding in order of decreasing affinity were: 13 and 15 kDa calcium-binding domain of sheathlin >27 and 29 kDa calcium-binding proteins >32 kDa enamelin >89 kDa enamelin >6.5 kDa, 25 kDa, 23 kDa, 20 kDa, 13 kDa, 5.3 kDa amelogenins. It is concluded that if enamel proteins have similar calcium-binding properties in vivo as have been measured in vitro, they would tend to buffer the free calcium ion concentration in enamel fluid.

Synergistic effect of cadmium chloride and acetaldehyde on cytotoxicity and its prevention by quercetin and glycyrrhizin

Cadmium chloride at concentrations of 10-50mM and acetaldehyde (AA) at 1-5mM showed synergistic toxic effects on V79 cells in vitro. Furthermore, synergistic effects of these chemicals were also observed in mutagenicities of the Hprt gene within certain dose ranges (cadmium chloride 5-10mM, and AA 1-2.5mM). Moreover, lipid peroxide formation, malondialdehyde (MDA) formation, detected by 2-thiobarbituric acid (TBA) reaction and the mitochondrial membrane potentials detected by rhodamine 123 uptake were significantly increased with the combined effect of cadmium and AA in V79. Thus, the cytotoxicity and genotoxicity displayed by combination of these chemicals can be considered to be associated with oxidative stress. Further, these effects were efficiently reduced by quercetin and less efficiently with glycyrrhizin.

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

Areca quid chewing has been linked to oral submucous fibrosis and oral cancer. Arecoline, a major areca nut alkaloid, is considered to be the most important etiologic factor in the areca nut. In order to elucidate the pathobiological effects of arecoline, cytotoxicity assays, cellular glutathione S-transferase (GST) activity and lipid peroxidation assay were employed to investigate cultured human buccal mucosal fibroblasts. To date, there is a large proportion of areca quid chewers who are also smokers. Furthermore, nicotine, the major product of cigarette smoking, was added to test how it modulated the cytotoxicity of arecoline. At a concentration higher than 50 microg/ml, arecoline was shown to be cytotoxic to human buccal fibroblasts in a dose-dependent manner by the alamar blue dye colorimetric assay (P<0.05). In addition, arecoline significantly decreased GST activity in a dose-dependent manner (P<0.05). At concentrations of 100 microg/ml and 400 microg/ml, arecoline reduced GST activity about 21% and 46%, respectively, during a 24 h incubation period. However, arecoline at any test dose did not increase lipid peroxidation in the present human buccal fibroblast test system. The addition of extracellular nicotine acted synergistically on the arecoline-induced cytotoxicity. Arecoline at a concentration of 50 microg/ml caused about 30% of cell death over the 24 h incubation period. However, 2.5 mM nicotine enhanced the cytotoxic response and caused about 50% of cell death on 50 microg/ml arecoline-induced cytotoxicity. Taken together, arecoline may render human buccal mucosal fibroblasts more vulnerable to other reactive agents in cigarettes via GST reduction. The compounds of tobacco products may act synergistically in the pathogenesis of oral mucosal lesions in areca quid chewers. The data presented here may partly explain why patients who combined the habits of areca quid chewing and cigarette smoking are at greater risk of contracting oral cancer.

Cytotoxic effects of denture base materials on a permanent human oral epithelial cell line and on primary human oral fibroblasts in vitro

PURPOSE

The objective of this study was to determine the cytocompatibility of three different extracts of denture base resins and to compare the cytotoxic effect of these materials on a human oral epithelial KB cell line and primary human oral fibroblasts derived from buccal mucosa.

MATERIALS AND METHODS

Set specimens from a heat-cured resin, a self-cured resin, and a light-cured resin were eluted with culture medium for 1, 3, and 5 days. Cytotoxicity was judged using tetrazolium bromide reduction assay.

RESULTS

The eluates from self-cured, heat-cured, and light-cured denture base resins were cytotoxic to primary human buccal fibroblast cultures and KB cells. Self-cured resin was the most toxic denture base material among the chemicals tested in all cultures. The cytotoxicity decreased in the order of self-cured resin > heat-cured resin > light-cured resin for KB cells. The rank for buccal fibroblast cells was self-cured resin > heat-cured resin > light-cured resin.

CONCLUSION

The influence of the cytotoxicity depended on the materials tested and the cell culture system used. The use of both permanent and primary cells is recommended for a better screening of the cytotoxic effects of denture base resins.

Caspase activation in response to cytotoxic Rana catesbeiana ribonuclease in MCF-7 cells

Rana catesbeiana ribonuclease (RC-RNase) and onconase were proven to own anti-tumor activity. While molecular determinants of onconase-induced cell death have become more explicit, the RC-RNase-induced death pathway remains presently unknown. Here we demonstrated that RC-RNase-induced molecular cascades in caspase-3-deficient MCF-7 cells did not include activation of initiation caspase-8 and -9. Cleavage timing suggested that procaspase-2 and -6 might be processed by active caspase-7 in MCF-7 cells. Caspase-7 was also responsible for cleavage of the poly(ADP-ribose) polymerase. Furthermore, we reported that overexpression of Bcl-X(L) could raise the survival rates of MCF-7 cells treated with RC-RNase and onconase.

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.

Murine enamelin: cDNA and derived protein sequences

Enamelin is the largest enamel protein. Recently we reported the characterization of a cDNA clone encoding porcine enamelin. The secreted protein has 1104 amino acids--over 6 times the length of amelogenin (173 amino acids) and almost 3 times the lengths of sheathlin (395 amino acids) and tuftelin (389 amino acids). Immunohistochemistry has shown that uncleaved porcine enamelin concentrates at the growing tips of the enamel crystallites while its cleavage products localize to rod and interrod enamel. Here we report the isolation and characterization of cDNA encoding murine amelogenin and demonstrate the tooth specificity of porcine enamelin. The murine clone is 4154 nucleotides in length and encodes a protein of 1274 amino acids. In the absence of post-translational modifications murine enamelin has an isotope averaged molecular mass of 137 kDa and an isoelectric point of 9.4. Multiple tissue Northern blot analyses detect porcine enamelin mRNA in developing teeth but not in liver, heart, brain, spleen, skeletal muscle and lung. Mouse and porcine enamelin share 61% amino acid identity and 75% DNA sequence identity. Mouse enamelin has 14 tandemly arranged copies of an 11 amino acid segment that is found only once in porcine enamelin.

Biochemical characterization of recombinant mouse amelogenins: protein quantitation, proton absorption, and relative affinity for enamel crystals

Four recombinant mouse amelogenins, which varied by the presence or absence of the exon 4 encoded segment as well as the carboxyl-terminus were heterologously expressed and purified from bacteria. The rM193 and rM179 contain the carboxyl-terminus, whereas the rM180 and rM166 do not. The rM193 and rM180 contain the polypeptide segment encoded by exon 4 of the amelogenin gene. A precisely weighed sample of purified rM179 was quantified by Lowry, Bicinchoninic Acid and Bradford assays. It was determined that these protein quantification methods characteristically under or overestimate the amount of amelogenin. The calculated correction factors were: Lowry (x 1.35), BCA (x 1.96), and Bradford (x 0.78). Recombinant mouse amelogenin (rM179) was characterized with respect to its hydrogen ion binding properties. The protein absorbs 11.9 +/- 1.7 protons during a pH change from 8.0 to 5.0, suggesting that amelogenins buffer the enamel fluid in vivo. Crystal binding experiments were performed using rM193, rM180, rM179 and rM166. The carboxyl-terminus enhanced the binding of amelogenin to enamel crystals while the exon 4 encoded segment did not appreciably affect crystal binding.

Enamel matrix serine proteinase 1: stage-specific expression and molecular modeling

Enamel proteins are cleaved by proteinases soon after their secretion by ameloblasts. Intact proteins concentrate in the outer enamel at or near the growing tips of the enamel crystallites while cleavage products accumulate in the deeper enamel. In the transition and early maturation stages there is a dramatic increase in proteolytic activity. This activity, coupled with the diminished secretory and increased reabsorptive functions of ameloblasts, leads to a precipitous fall in the amount of enamel protein in the matrix. Recently we have cloned and characterized an mRNA encoding a tooth-specific serine proteinase designated enamel matrix serine proteinase 1 (EMSP1) [Simmer et al., JDR (1998) 77: 377]. EMSP1 can be detected in the inner enamel during the secretory stage and its activity increases sharply during the transition stage. Stage-specific Northern blot analysis demonstrates this increase is accompanied by a parallel increase in the amount EMSP1 mRNA. A 3-dimensional computer model of EMSP1, based upon the crystal structure of bovine trypsin, has been generated and analyzed. All six disulfide bridges as well as the active site are conserved. Changes in the peptide binding region and the specificity pocket suggest that interaction of the proteinase with protein substrates is altered, potentially causing a shift in substrate specificity. The calcium binding region of trypsin is thoroughly modified suggesting that the calcium independence of EMSP1 activity is due to an inability to bind calcium. The three potential N-linked glycosylation sites, N104, N139 and N184, are in surface accessible positions away from the active site.

Synergistic cytotoxicity of Rana catesbeiana ribonuclease and IFN-gamma on hepatoma cells

RC-RNase purified from Rana catesbeiana (bullfrog) oocytes is a pyrimidine-guanine sequence-specific ribonuclease. RC-RNase is derived from the RNase superfamily genes exerting distinct ribonucleolytic activity and possesses cytotoxicity to tumor cells, but rarely to primary cells. In this study, we utilized RC-RNase to function with antiproliferative cytokines. The combination with TNF-alpha or TNF-beta would not aggravate cell death. However, the combination with IFN-gamma could induce synergistic cytotoxicity verified by XTT assays toward three hepatoma cell lines bearing different differentiation stages. The distinct cytotoxicity from RC-RNase or RC-RNase/IFN-gamma on different hepatoma cells was correlated with the differentiation extent but not the proliferation rate of the cells. Despite the synergistic cytotoxicity and severe mitochondrial disruptions in the RC-RNase/IFN-gamma-treated cells, we scarcely detected any significant feature of apoptosis or necrosis by FACS analysis on annexin-V/propidium iodide staining. The mechanisms of cell death triggered by RC-RNase or RC-RNase/IFN-gamma require further investigation.

The influence of inserting a Fuji pressure sensitive film between the tibiofemoral joint of knee prosthesis on actual contact characteristics

OBJECTIVE

To investigate the influence of inserting a Fuji pressure sensitive film between the tibiofemoral joint of knee prosthesis on actual contact characteristics.

DESIGN

A finite element analysis was used to investigate the alteration of contact characteristics of the tibiofemoral joint due to inserting a pressure sensitive film between the contacting surfaces.

BACKGROUND

The discrepancy between actual contact behaviors of tibiofemoral joint of knee prosthesis and the measurement using Fuji pressure sensitive film was not discussed extensively. The change of direct contact circumstance of the tibiofemoral joint due to inserting a pressure sensitive film was not well reported.

METHOD

A two-dimensional finite element model of the tibiofemoral joint of knee prosthesis in the sagittal plane was constructed. Four different radii of the femoral component were used to investigate the conformity effect. Two-layers of plane strain element were used to model the pressure sensitive film. The influence of inserting a pressure sensitive film on the actual contact characteristics was analyzed by comparing the results of the change in contact radius.

RESULTS

Inserting a pressure sensitive film between contacting surfaces would disturb the original contact behaviors, especially in the lowest conformity design. The maximum difference of contact radius between the model simulating actual contact circumstance and the model with inserting a pressure sensitive film between contacting surface was 77% in the lowest conformity condition at the smallest load.

CONCLUSIONS

This study proposes a quantitative analysis of contact characteristics in the tibiofemoral joint of knee prosthesis between the models with and without inserting a pressure sensitive film into the contact surface. The measurement of contact area in artificial tibiofemoral joints by using Fuji pressure sensitive film is always overestimated its true contact area by 14-77%.

RELEVANCE

This study revealed the measurement of contact characteristics of artificial tibiofemoral joints by using Fuji pressure sensitive film which depends on not only the applied load, but also the conformity and material properties of the contact surface. Therefore, the information of the conformity and material properties of the contact surface should be provided as well as the applied load wherever a measurement of contact characteristics using Fuji pressure sensitive film is analyzed and interpreted.

Differentiation status modulates transcription factor NF-kappaB activity in unstimulated human hepatocellular carcinoma cell lines

We report herein a novel finding that under an unstimulated condition, a group of four human hepatocellular carcinoma (HCC) cell lines with varying degrees of differentiation, can spontaneously activate NF-KB. The propensity of activation coincided inversely with the differentiation status, with order being SK-Hep-1 > J5 > Hep3B > HepG2. Further studies indicate that this pattern of activation correlates excellently with the descending order of intracellular GSH/GSSG ratios as well as with the ascending order in the ability of these cells to generate hydrogen peroxide. Taken together, our data suggest that differentiation status may play a pivotal role in modulating intracellular thiol redox status and the extent of catalase expression, which may be crucial in the control of NF-kappaB activity in these HCC cells.

Cloning human enamelin cDNA, chromosomal localization, and analysis of expression during tooth development

Enamelin is the largest protein in the enamel matrix of developing teeth. In the pig, enamelin is secreted as 186-kDa phosphorylated glycoprotein, which is rapidly processed by enamel proteinases into smaller cleavage products. During the secretory stage of enamel formation, enamelin is found among the crystallites in the rod and interrod enamel and comprises roughly 5% of total matrix protein. Although the function of enamelin is unknown, it is thought to participate in enamel crystal nucleation and extension, and the regulation of crystal habit. Here we report the results of enamelin in situ hybridization in a day 1 mouse developing incisor that shows that enamelin is expressed by ameloblasts, but not by odontoblasts or other cells in the dental pulp. The restricted pattern of enamelin expression makes the human enamelin gene a prime candidate in the etiology of amelogenesis imperfecta (AI), a genetic disease in which defects of enamel formation occur in the absence of non-dental symptoms. We have cloned and characterized a full-length human enamelin cDNA and determined by radiation hybrid mapping and fluorescent in situ hybridization (FISH) that the gene is located on chromosome 4q near the ameloblastin gene in a region previously linked to local hypoplastic AI in six families. These findings will facilitate the search for specific mutations in the enamelin gene in kindreds suffering from amelogenesis imperfecta.

Induction of apoptosis in KB cells by pingyangmycin

Pingyangmycin (PYM; Bleomycin A(5)), an antitumour antibiotic is currently used during anticancer therapy. Previous experiments demonstrated that the therapeutic efficiency of PYM for treatment of malignant tumours is considered to be related to its ability to cause DNA strand breaks in vitro. However, very little is known about the interaction of PYM with the target cells, and it is still unclear how PYM enters the cells. In this study, cell death induced by PYM was studied in a human squamous cell carcinoma cell line (KB cells). In order to determine if cell death occurred by necrosis (reproductive cell death) or apoptosis (programmed cell death), KB cells were exposed to different concentrations of PYM and evaluated by biochemical and morphological criteria. Our results indicate that KB cells displayed an arrest in the G(2)-M phase of the cell cycle and became enlarged and polynucleated before dying at the low concentrations of PYM. In contrast, when cells were exposed to high concentrations of PYM, morphological changes identical to those usually associated with apoptosis were observed as well as internucleosomal digestion of genomic DNA. In conclusion, we demonstrate that PYM is able to induce two distinct modes of cell death depending on the doses of PYM.

Molecular characterization of an atypical old world strain of Peanut stunt virus

Northern blot analyses of RNAs from an Iranian strain of Peanut stunt virus (PSV-I Cucumovirus) using cloned cDNA probes to the genomic RNAs from two PSV strains, PSV-ER (subgroup I) and PSV-W (subgroup II), indicated that PSV-I RNA-3 is derived from a subgroup II strain. No hybridization signals, however, were detected with PSV-I RNAs 1 and 2 suggesting they are distinct from both subgroups I and II. Nucleotide (nt) sequence analysis of cloned cDNA fragments (1-1.5 kbp in size) representing PSV-I RNAs 1 and 2 showed that PSV-I is more closely related to subgroup II strains than to any other sequenced cucumovirus. The percent nt identity between RNA-1 sequences from PSV-I and PSV-ER or between PSV-I and PSV-W were 79.1% and 88.8%, respectively. The corresponding values for RNA-2 were 77.5% and 86.7%. Sequence comparison analyses of deduced amino acid sequence of cloned partial sequences of PSV-I RNAs 1 and 2 indicated that PSV-I 1a and 2a proteins are most closely related to those of subgroup II strains (93% identity). PSV-I supported the replication and encapsidation of PSV G-satellite RNA (G-satRNA), but not cucumber mosaic virus WL1-satRNA. PSV-I may be perceived as an Old World derivative of subgroup II strains, or it may represent a natural reassortment between a subgroup II (RNA-3) and an as yet uncharacterized subgroup of PSV strains (RNAs 1 and 2).

Complete nucleotide sequence of bean pod mottle virus RNA1: sequence comparisons and evolutionary relationships to other comoviruses

The complete nucleotide sequence of bean pod mottle comovirus (BPMV) RNA 1 was determined. It is 5983 nucleotides long, excluding the poly(A) tail, and encodes a polyprotein of 1850 amino acid (aa) residues. Multiple alignments of the deduced aa sequence of BPMV polyprotein with those of cowpea mosaic virus (CPMV), red clover mottle virus (RCMV) and cowpea severe mosaic virus (CPSMV) indicated that BPMV RNA1 encodes the predicted set of five mature proteins: the equivalent of CPMV 32K protease cofactor, 58K putative helicase, VPg, 24K protease and 87K putative RNA-dependent RNA polymerase. Of the four proposed cleavage sites in BPMV RNA1 polyprotein, the one at the 32K/58K site (Q/A) is distinct for BPMV polyprotein and those at the 58K/VPg and VPg/24K junctions (Q/S and Q/M, respectively) are identical in all four comovirus polyproteins. Sequence comparison and phylogenetic analysis revealed that BPMV RNA1 is more closely related to CPSMV than to CPMV or to RCMV.

Endophthalmitis as a complication of meningococcal meningitis: report of one case

Metastatic meningococcal endophthalmitis, although rare, is a rapidly progressive and sight-threatening infection. We present a 10-month-old infant with meningococcal meningitis who developed unilateral metastatic endophthalmitis. If patients develop a sepsis-like picture with cloudy cornea and purulent conjunctivitis, we have to consider the possibility of endophthalmitis and full ophthalmological evaluations are indicated. Treatment should be started as early as possible. The outcome of endophthalmitis is frequently permanent visual impairment. Endophthalmitis is a true medical emergency requiring early antibiotic therapy with full dose of antimicrobials to avoid morbidity and blindness.

Characterization of recombinant pig enamelysin activity and cleavage of recombinant pig and mouse amelogenins

Enamelysin (MMP-20) is a tooth-specific matrix metalloproteinase that is initially expressed by ameloblasts and odontoblasts immediately prior to the onset of dentin mineralization, and continues to be expressed throughout the secretory stage of amelogenesis. During the secretory stage, enamel proteins are secreted and rapidly cleaved into a large number of relatively stable cleavage products. Multiple proteinases are present in the developing enamel matrix, and the precise role of enamelysin in the processing of enamel proteins is unknown. We have expressed, activated, and purified the catalytic domain of recombinant pig enamelysin, and expressed a recombinant form of the major secreted pig amelogenin rP172. These proteins were incubated together, and the digestion products were analyzed by SDS-PAGE and mass spectrometric analyses. We assigned amelogenin cleavage products by selecting among the possible polypeptides having a mass within 2 Daltons of the measured values. The polypeptides identified included the intact protein (amino acids 2-173), as well as 2-148, 2-136, 2-107, 2-105, 2-63, 2-45, 46-148, 46-147, 46-107, 46-105, 64-148, 64-147, and 64-136. These fragments of rP172 include virtually all of the major amelogenin cleavage products observed in vivo. We propose that enamelysin is the predominant proteinase that processes enamel proteins during the secretory phase of amelogenesis.

Cloning, characterization, and tissue expression pattern of mouse tuftelin cDNA

Tuftelin is a protein that has been suggested to function during enamel crystal nucleation. Published sequences for bovine tuftelin cDNA and genomic clones proposed different reading frames that radically affected the derived amino acid sequence of the tuftelin carboxyl-terminus. We have isolated and characterized a full-length mouse cDNA clone and a partial porcine cDNA clone that include the region of the proposed frame-shift. The mouse tuftelin clone is 2572 nucleotides in length, exclusive of the poly(A+) tail. Translation from the 5'-most ATG yields a protein of 390 amino acids with an isotope-averaged molecular mass of 44.6 kDa and an isoelectric point of 5.9. Comparison of the bovine, mouse, and porcine cDNAs supports the revised bovine tuftelin amino acid sequence and suggests that the bovine tuftelin translation initiation codon be re-assigned to a more 5' ATG. Re-assigning the translation initiation codon lengthens the tuftelin protein by 52 amino acids, 51 of which are identical between bovine and mouse. At the carboxyl-terminus, the revised bovine and the mouse sequences match at 39 of the final 42 amino acid positions, compared with 2 identities with the originally published bovine reading frame. Northern blot analysis reveals that tuftelin is not ameloblast-specific but is expressed in multiple tissues, including kidney, lung, liver, and testis. Two tuftelin RNA messages, of 2.6 and 3.2 kb, were detected. DNA sequence characterization of an RT-PCR amplification product confirmed expression of tuftelin in kidney, and identified an alternatively spliced mouse tuftelin mRNA lacking exon 2.

Reparative dentin formation in rat molars after direct pulp capping with growth factors

Growth factors involved in normal wound healing may promote tissue repair when applied as a direct pulp capping medication. A minimal pulp exposure was made in rat molars, a pulp capping medication was placed, and the cavity was sealed. Epidermal growth factor, basic fibroblast growth factor, insulin-like growth factor II, platelet-derived growth factor-BB, and transforming growth factor-beta 1 (TGF-beta 1)--each absorbed onto a sterile collagen membrane (BioMend; Calcitek, Carlsbad, CA)--were used separately as pulpal medicaments. Dycal, unimpregnated collagen membrane, and no medication were used as controls. Eight samples from each treatment regimen were collected 2 and 3 weeks after surgery. Pulpal soft and hard tissue responses were graded. Data were analyzed by one-way ANOVA and Tukey-Kramer tests. No significant differences were detected after 2 wk. Pulp treated with TGF-beta 1 showed significantly improved soft and hard tissue healing at week 3, compared with the procedure control. We conclude that TGF-beta 1 as a pulp-capping medication enhances reparative dentin formation in rat molars.

Production of infectious RNA transcripts from full-length cDNA clones representing two subgroups of peanut stunt virus strains: mapping satellite RNA support to RNA1

Full-length cDNA clones from which infectious transcripts could be generated were constructed from the genomic RNAs of two distinct strains of peanut stunt cucumovirus (PSV), PSV-ER and PSV-W. PSV-ER, a subgroup I strain, is known to support efficient replication of satellite RNA (satRNA) in infected plants, whereas PSV-W, a subgroup II strain, does not support satRNA replication. Although artificial reassortants (pseudorecombinants) of all possible combinations of infectious transcripts representing RNA1, RNA2 and RNA3 were infectious, only those having RNA1 from PSV-ER supported the replication of satRNA. These results demonstrate conclusively that support of PSV satRNA replication maps to RNA1. Comparisons of secondary structure predictions of the C-terminal helicase-like domain of the 1a proteins of four PSV strains belonging to two subgroups did not reveal any obvious differences between strains that differ in satRNA support. The complete nucleotide sequence of RNA1 from strains PSV-ER and PSV-W were determined and found to be 79% identical. Sequence comparison analysis of RNA1 sequences of cucumoviruses confirmed the placement of the PSV strains into two distinct subgroups.

Purification, characterization, and cloning of enamel matrix serine proteinase 1

The maturation of dental enamel succeeds the degradation of organic matrix. Inhibition studies have shown that this degradation is accomplished by a serine-type proteinase. To isolate and characterize cDNA clones encoding this proteinase, we used two degenerate primer approaches to amplify part of the coding region using polymerase chain-reaction (PCR). First, we purified the proteinase from porcine transition-stage enamel matrix and characterized it by partial protein sequencing. The enzyme was isolated from the neutral soluble enamel extract by successive ammonium sulfate precipitations, hydroxyapatite HPLC, reverse-phase HPLC, DEAE ion exchange, and affinity chromatography with a Benzamidine Sepharose 6B column. The intact protein and lysylendopeptidase-generated cleavage products were characterized by amino acid sequence analyses. Degenerate oligonucleotide primers encoding two of the polypeptide sequences were synthesized. In a complementary strategy, degenerate oligonucleotide primers were designed against highly conserved active-site regions of chymotrypsin-like proteinases. Both approaches yielded PCR amplification products that served as probes for screening a porcine enamel organ epithelia-specific cDNA library. The longest full-length clone is 1133 nucleotides and encodes a preproprotein of 254 amino acids. We designate this protein enamel matrix serine proteinase 1 or EMSP1. The active protein has 224 amino acids, an isotope-averaged molecular mass of 24.1 kDa, and an isoelectric point of 6.0. Multiple-tissue Northern analysis indicates that EMSP1 is a tooth-specific protein. Gelatin enzymography shows a dramatic increase in EMSP1 activity in the transition-stage enamel matrix. EMSP1 is most homologous to kallikriens and trypsins.

Molecular Evidence That Strain BV-15 of Peanut Stunt Cucumovirus Is a Reassortant Between Subgroup I and II Strains

ABSTRACT In Northern hybridization assays, RNA1 of peanut stunt virus (PSV) strain BV-15 hybridized strongly with a cloned cDNA probe to RNA1 from strain PSV-W (subgroup II). Cloned probes to PSV-W RNA2 and RNA3, however, did not hybridize with the corresponding RNAs from strain BV-15. The complete nucleotide sequence of PSV-BV-15 RNA2 has been determined, and sequence comparison analysis showed that it is closely related to PSV subgroup I strains; the percent nucleotide sequence identity between PSV-BV-15 RNA2 and RNA2 sequences from PSV subgroup I and II strains were 90.5 and 75%, respectively. The possibility that PSV-BV-15 RNA2 may contain short regions derived from a subgroup II strain (i.e., represent a mosaic structure indicative of recombination) was investigated. Results indicated, however, that the entire PSV-BV-15 RNA2 sequence is derived from a subgroup I strain. PSV-BV-15 RNA3 has previously been shown to belong to subgroup I strains. These results thus establish that PSV strain BV-15 is a natural reassortant between PSV subgroups I and II strains. A reverse transcription-po-lymerase chain reaction assay is proposed for differentiating between this reassortant strain and PSV strains in subgroups I and II.

Proteolytic activity of opossum tooth extracts

Amelogenins are the main component of the developing enamel matrix. In placental mammals, amelogenins are rapidly cleaved following their secretion. HPLC fractionation of tooth extracts produces a complex chromatographic profile. The fractions are rich in amelogenin cleavage products that generally retain the amino-terminus of the parent protein but have varying lengths of peptide removed from the original carboxyl-terminus. In contrast, HPLC fractionation of opossum tooth extracts produces a simple profile with a single major chromatographic peak. SDS-and Western blot analyses demonstrated that most of the amelogenin consisted of a prominent protein band that migrated at 28 kDa. Mass spectroscopy confirmed the presence of two uncleaved, alternatively spliced forms of opossum amelogenin, Op202 and Op57, but did not detect major amelogenin cleavage products evident in tooth extracts from placental mammals. Amino acid composition analysis supported the conclusion that uncleaved amelogenin is the major component in the developing enamel matrix. Enzymogram analyses using gelatin, casein and recombinant amelogenin as substrates, comparing porcine, rat and opossum tooth extracts, suggested that fewer proteinases are present in opossum. These results identify potentially significant differences in the proteolytic processing of amelogenins between metatherian and eutherian mammals.

Derived protein and cDNA sequences of hamster amelogenin

Hamster enamel protein extracts were analyzed by RP-HPLC and the isolated fractions by SDS-and Western blotting using polyclonal antibodies against recombinant mouse amelogenin and anti-peptide antibodies against the mouse exon 4-encoded sequence. Total RNA was extracted from enamel organ epithelia and, using a 3' rapid amplification of cDNA ends (3' RACE) technique, the coding regions for three different amelogenin isoforms were cloned along with the 3' non-coding region. DNA sequencing revealed that the hamster amelogenin isoforms are 180, 73 and 59 amino acids in length, respectively. The 59-residue amelogenin corresponds to the leucine-rich amelogenin protein (LRAP), the 73-residue amelogenin corresponds to LRAP with the inclusion of the exon 4-encoded sequence, while the 180-residue amelogenin is the most abundant amelogenin isoform. Edman degradation was performed on purified hamster amelogenin, which provided the amino acid sequence in the region encoded by the 5' PCR amplification primer used in cloning. Therefore, the entire derived amino acid sequence of hamster amelogenin was revealed. The hamster amelogenin amino acid sequence was aligned with all its known homologues. Hamster differs from rat and mouse amelogenin at only three amino acid positions. Southern blot analysis using a panel of restriction enzymes gave the same pattern for hamster DNA obtained from males and females, suggesting that in hamster, as in mouse, amelogenin is expressed from a single gene located on the X chromosome.

Cloning and characterization of porcine enamelin mRNAs

Dental enamel forms by matrix-mediated biomineralization. The components of the developing enamel matrix are generally specific for that matrix. The primary structures of three enamel proteins-amelogenin, tuftelin, and sheathlin (ameloblastin/amelin)-have been derived from cDNA sequences. Here we report the cloning and characterization of mRNA encoding a fourth enamel protein: enamelin. The longest porcine enamelin cDNA clone has 3907 nucleotides, exclusive of the poly(A) tail. The primary structure of the secreted protein is 1104 amino acids in length. Without post-translational modifications, the secreted protein has an isotope-averaged molecular mass of 124.3 kDa and an isoelectric point of 6.5. Polymerase chain-reaction phenotyping of enamelin cDNA suggests that porcine enamelin transcripts are not alternatively spliced and use a single polyadenylation/cleavage site. Immunohistochemical and Western blot analyses with an affinity-purified antipeptide antibody specific for the enamelin carboxyl terminus demonstrate that enamelin is synthesized and secreted by secretory-phase ameloblasts. The parent protein is a 186-kDa glycoprotein that concentrates along the secretory face of the ameloblast Tomes' process. Intact enamelin and proteolytic cleavage products containing its carboxyl terminus are limited to the most superficial layer of the developing enamel matrix, while other enamelin cleavage products are observed in deeper enamel.

Evidence for the occurrence of two distinct subgroups of peanut stunt cucumovirus strains: molecular characterization of RNA3

Strains of peanut stunt cucumovirus (PSV) were classified into two distinct subgroups, I and II, based on Western and Northern blot analyses using antisera and cloned cDNA probes to strains PSV-ER and PSV-W. These results were corroborated by nucleotide sequence analyses of full-length cDNA clones of RNA3 from representative strains of the two subgroups. Whereas the percentage nucleotide sequence identity between PSV-ER (or PSV-J) and PSV-W RNA3s was determined to be 80%, the corresponding value between strains ER and J was 91%, confirming that strains ER and J belong to the same subgroup (subgroup I) whereas strain W belongs to a separate subgroup (subgroup II). PSV-W and PSV-ER RNA3s are 2173 and 2188 nucleotides long, respectively. Each is dicistronic, encoding a putative movement protein (3a protein) and a coat protein (CP). The intercistronic and 5' untranslated region (UTR) sequences of PSV strains, unlike those of cucumber mosaic cucumovirus (CMV) strains, are highly conserved and thus not useful for distinguishing the two subgroups. However, the 3' UTR sequences of PSV strains, like those of CMV strains, can discriminate between the two subgroups since strains within the same subgroup are 95% identical in their 3' UTRs whereas those in different subgroups are only 74-78% identical. PSV-W and PSV-ER RNA4s were determined to be 994 and 1006 nucleotides long, respectively. PSV 3a and CP genes have higher percentage nucleotide sequence identities to those of tomato aspermy cucumovirus than to those of CMV.

Pseudomonas aeruginosa endophthalmitis in prematurity: report of two cases

Invasive bacterial eye infections in the neonate range from perforating keratitis to endophthalmitis. Endophthalmitis secondary to Pseudomonas aeruginosa has gained clinical and therapeutic importance since mortality rates are high and prognosis concerning preservation of vision is poor, especially in premature infants. We presented two cases with meningitis, septicemia and P. aeruginosa endophthalmitis. If premature infants develop a sepsis-like picture with cloudy cornea and purulent conjunctivitis, we have to consider the possibility of endophthalmitis and do a full ophthalmologic evaluation. Treatment should be started early and consists of systemic antibiotic therapy, as in septicemia. As P. aeruginosa spreads easily, prompt isolation and strict handwashing are indicated.

Sheathlin: cloning, cDNA/polypeptide sequences, and immunolocalization of porcine enamel sheath proteins

Sheath proteins designate low-molecular-weight non-amelogenin enamel polypeptides and their parent protein, which concentrate in the sheath space separating rod and inter-rod enamel (Uchida et al., 1995). Two porcine sheath proteins, with apparent molecular weights of 13 and 15 kDa, are characterized by protein sequencing. The primary structures of these polypeptides match a portion of the derived amino acid sequences of clones isolated from a porcine enamel organ epithelia-specific cDNA library. Sheath protein RNA messages differ by the inclusion or deletion of a 45-nucleotide segment and by the use of three alternative polyadenylation/cleavage sites. The secreted proteins are 395 and 380 residues in length, with molecular masses of 42,358 and 40,279 Daltons and calculated isoelectric points of 6.3 and 6.7, respectively. Polyclonal antibodies were raised against a synthetic peptide having the sheathlin-specific sequence EHETQQYEYSGGC. Immunohistochemistry with this antibody demonstrates that the protein encoded by the sheathlin cDNA is preferentially localized in the sheath space. We propose that the porcine sheath proteins and their proteolytic cleavage products be designated "sheathlin".

Cloning, characterization, and heterologous expression of exon-4-containing amelogenin mRNAs

The formation of dental enamel is dependent upon amelogenins, a family of proteins constituting most of the developing enamel matrix. Depending upon the species, these enamel proteins are expressed from either one or two copies of the amelogenin gene. Each gene directs the synthesis of a variety of amelogenin isoforms through alternative splicing of their pre-mRNA transcript(s). Before the role of amelogenins in dental enamel formation can be better understood, one must know the isoforms that are secreted and their biochemical properties. Previously, we cloned and characterized 7 mouse amelogenin RNA messages generated by alternative splicing. The largest amelogenin cDNA encoded a 194-residue amelogenin isoform which was the only clone to contain the 42-nucleotide exon 4 segment. Anti-peptide antibodies raised against the derived translation of this exon revealed an unexpectedly diverse assortment of murine amelogenins, suggesting that additional splicing variants could contain the exon 4 coding region. Using exon-4-specific oligonucleotide primers, we have amplified, cloned, and characterized three different amelogenin RNA messages. These messages encode amelogenin polypeptides (exclusive of signal peptides) 194, 170, and 73 amino acids in length. The isotope-averaged molecular weights for the deduced, single-phosphorylated, proteins are 21,897.1, 19,113.9, and 8176.5 Daltons, respectively. Splice-site selection for the generation of these mRNAs was identical to that of the previously characterized messages for the M180, M156, and M59 except for the inclusion of exon 4. The exon-4-containing amelogenin isoforms were heterologously expressed in E. coli by means of the pET11 expression system (Novagen, Madison, WI).

Comparative HPLC, SDS-PAGE, and immunoblot analyses of dental enamel proteins

The primary structures of amelogenins expressed from different genes vary because of DNA sequence divergence and variations in alternative RNA splicing. The pattern of splicing is unique for each amelogenin gene yet investigated, even when two copies of the gene are expressed in the same cell. Despite the high conservation of amelogenin sequences, diversity in the pattern of RNA splicing leads to significant differences in the number and character of amelogenin isoforms in the developing enamel matrix. Since conservation of molecular structure is an indicator of functional significance, we compared enamel protein preparations from rat, porcine, rabbit, and opossum developing tooth organs. Enamel extracts were fractionated by reversed-phase high-performance liquid chromatography (HPLC) and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Western blot analyses were performed with polyclonal antibodies raised against recombinant murine amelogenin and the polypeptide encoded by murine exon 4. The opossum enamel extract produced the simplest chromatogram, suggesting that fewer proteins are secreted into the developing enamel matrix. The predominant opossum amelogenin has an apparent molecular mass of 28 kDa and reacts strongly with the recombinant amelogenin antibody but is not recognized by the murine exon 4 antibody. Opossum amelogenin mRNA was amplified with murine amelogenin primers specific for the amino- and carboxyl-terminal coding regions. The mobility of the amplification products on 4% agarose gels indicates that the leucine-rich amelogenin polypeptide (LRAP) is expressed in the opossum and that the major amelogenin is larger than its homologue in the mouse. We conclude that the alternative splicing of amelogenins pre-dates the metatherian and eutherian divergence over 100 million years ago.

Cloning, cDNA sequence, and alternative splicing of porcine amelogenin mRNAs

In mammals, the organic matrix of developing enamel is dominated by amelogenins. To investigate the expression of proteins secreted into the developing enamel matrix, we have constructed a porcine enamel organ epithelia-specific cDNA library. The amelogenin fraction of the cDNA library was characterized by the cloning of amelogenin-specific polymerase chain-reaction (PCR) amplification products, 5' and 3' rapid amplification of cDNA ends (RACE), and by helper phage rescue of unamplified clones. Clones were characterized that encode porcine amelogenin isoforms 173, 157, 56, 41, and 40 amino acids in length. The structure of the porcine amelogenin gene differs from that of any of those yet described. There are two homologous but distinct exons 1, 2, and 7. One of the two exon 7s can vary in length depending upon the selection of either of two polyadenylation signal/cleavage sites. As a rule, a given exon 1 always pairs with the same exon 2 but can be associated with either exon 7. Despite significant sequence divergence within these exons, no differences are observed in exons 3, 5, and 6. We interpret these findings as evidence of a single amelogenin gene expressed from two promoters; however, the results do not exclude the existence of a second amelogenin gene. The variability generated through the use of alternate promoters and exon 7s primarily affects the non-coding regions of the message. A given amelogenin isoform expressed from the two promoters displays four amino acid differences within the signal peptide, while the secreted proteins are identical. Similarly, the alternative use of exon 7 does not alter the structure of the protein products. The pattern of RNA splicing of amelogenin pre-mRNAs is different for the transcripts expressed from the two promoters. The 173- and the 56-residue amelogenins can be expressed from either promoter, while the 157-residue amelogenin is generated by only one of the two promoters.

Cloning, DNA sequence, and alternative splicing of opossum amelogenin mRNAs

The enamel layer that covers the surfaces of teeth is thickest and most highly mineralized in mammals. The durability of mammalian enamel may have allowed for selection against the lifelong replacement of teeth that is observed in other vertebrates. Variation in enamel structure among animals is thought to be the result of evolutionary changes in the constituents of the developing enamel matrix. In placental mammals, the principal component of this matrix is amelogenin. We have determined the complete primary structures of two opossum amelogenins through a combination of protein sequencing, cloning, and DNA sequencing. RNA messages were cloned that encode 202- and 57-residue amelogenins, which are presumed to be expressed from the same gene but differ due to alternative splicing of identical pre-mRNAs. Edman degradation of the larger amelogenin ran for 42 cycles and yielded the sequence: IPLPPHPGHPGYINFS YEVLTPLKWYQSMMRQQYPSYGYEPM. The derived 202-residue amelogenin, assuming that serine 16 is phosphorylated, has an isotope-averaged molecular mass of 23,023.75 Daltons and a pI of 6.2. This is the largest amelogenin yet characterized. The increase in length is due to the presence of a 30-residue tandem repeat of QP(I/M) in exon 6 in the same position as a similar, but shorter, repeat expressed from the bovine X-chromosome. The 57-residue amelogenin, which is known from other organisms as the leucine-rich amelogenin protein (LRAP), has an isotope-averaged molecular mass of 6764.75 Daltons and a pI of 5.5. The opossum enamel protein is highly homologous to those previously characterized in eutherians and demonstrates that amelogenins were refined structurally prior to the metatherian/eutherian divergence between 100 and 150 million years ago.

The conserved, hydrophilic and arginine-rich N-terminal domain of cucumovirus coat proteins contributes to their anomalous electrophoretic mobilities in sodium dodecylsulfate-polyacrylamide gels

Although the Mr values of the coat proteins (CPs) of several cucumoviruses have been calculated from their deduced amino acid sequences to be approximately 24,000, the experimentally determined M(r) values using the Laemmli SDS-PAGE system were 30,000-31,000. Examination of the amino acid composition revealed that these CPs are neither highly acidic nor highly basic. Post-translational glycosylation or phosphorylation were also ruled out as contributing factors to the observed anomalous electrophoretic mobility because the products of in vitro translation of cucumovirus RNA 4 and in vivo bacterial expression of the cloned CP gene co-migrated with authentic cucumovirus CPs. Comparison of the hydropathy profiles of the CPs revealed the presence in each of a strikingly similar, highly hydrophilic N-terminal domain of 30-32 amino acid residues that contains a cluster of basic amino acids, mainly arginine. Selective chemical cleavage at tryptophan residues in the CPs of cucumoviruses, known to contain single tryptophan residues, yielded two peptides; an N-terminal peptide that contained the conserved hydrophilic domain and a C-terminal peptide. SDS-PAGE analysis showed that the N-terminal, but not the C-terminal, peptide exhibited the anomalous electrophoretic mobility.

Alternative splicing of the mouse amelogenin primary RNA transcript

A heterogeneous mixture of amelogenins can be extracted from developing tooth enamel matrix. In an attempt to discover the extent to which alternative splicing of the amelogenin primary RNA transcript can generate unique isoforms, we have conducted a thorough search for cDNAs amplified by reverse transcription-polymerase chain reaction (RT-PCR). Over 2400 colonies were screened by colony hybridization. Seven different alternatively spliced amelogenin mRNAs were isolated. The predicted translation products of the messages are 194, 180, 156, 141, 74, 59, and 44 amino acids in length. RT-PCR amplification products not predicted by these seven amelogenin cDNAs were characterized. The intron separating exons 5 and 6 was cloned and sequenced. Using rapid amplification of cDNA ends (RACE) techniques, the 5' ends of the amelogenin mRNAs were cloned and characterized. The finding that the same exon 1 is common to all of the cloned mRNAs indicates that mouse amelogenin is transcribed from a single promoter. The mouse amelogenin transcription and translation initiation sites, the 5' untranslated leader, and the segment encoding the signal peptide were determined. The distinctly nonamelogenin-like exon 4, first observed in human amelogenin cDNAs, has also been found in mice. Antibodies were raised to synthetic exon 4-encoded polypeptides and used to immunostain Western transfers and histologic tooth sections.

Nucleotide sequence of the genomic RNA of bamboo mosaic potexvirus

The complete nucleotide sequence of the genomic RNA of bamboo mosaic virus (BaMV) was determined by sequencing a set of overlapping cDNA clones and by direct sequencing of the viral RNA. The RNA genome of BaMV is 6366 nucleotides long [excluding 3'poly(A) tail] and contains six open reading frames (ORFs 1 to 6) coding for polypeptides with M(r) values of 155K, 28K, 13K, 6K, 25K and 14K, respectively. The genome organization and sizes of the encoded proteins are very similar to those of other potexviruses which have been sequenced except that ORF 6 lies completely within ORF 1. The first five putative proteins of the BaMV genome show identities ranging between 44 to 59%, 26 to 49%, 30 to 53%, 15 to 35% and 20 to 30%, respectively, to the corresponding ORFs of other members of the potexvirus group. However the putative product ORF 6 shows no significant similarity to those of other potexvirus ORF products.

Isolation and characterization of a mouse amelogenin expressed in Escherichia coli

A mouse cDNA encoding a 180 amino acid amelogenin was subcloned into the pET expression plasmid (Novagen, Madison, WI) for production in Escherichia coli. A simple growth and purification protocol yields 20-50 mg of 95-99% pure recombinant amelogenin from a 4.5-liter culture. This is the first heterologous expression of an enamel protein. The expressed protein was characterized by partial Edman sequencing, amino acid composition analysis, SDS-PAGE, Western blotting, laser desorption mass spectrometry, and hydroxyapatite binding. The recombinant amelogenin is 179 amino acids in length, has a molecular weight of 20,162 daltons, and hydroxyapatite binding properties similar to the porcine 173 residue amelogenin. Solubility analyses showed that the bacterially expressed protein is only sparingly soluble in the pH range of 6.4-8.0 or in solutions 20% saturated with ammonium sulfate. The purified protein was used to generate rabbit polyclonal anti-amelogenin antibodies which show specific reaction to amelogenins in both Western blot analyses of enamel extracts and in immunostaining of developing mouse molars.