Emergence of influenza A H1N2 reassortant viruses in the human population during 2001

Influenza A H1N2 viruses, which emerged during 2001, are genetic reassortants between H1N1 and H3N2 subtype viruses which have cocirculated in the human population since 1977. They possess a H1 hemagglutinin antigenically and genetically similar to contemporary A/New Caledonia/20/99 (H1N1)-like viruses and seven genes closely related to those of recent A/Moscow/10/99 (H3N2)-like viruses. The viruses have spread to many regions of the world and have predominated over H1N1 viruses in several countries. Since half of the amino acid changes which accumulated in the HAs of H1N1 viruses since 1995 are in residues implicated in receptor binding, functional changes in the H1 HA may have facilitated its replacement of the H3 HA and may contribute to the future epidemiologic significance of these H1N2 viruses.

Rapid molecular analysis of the haemagglutinin gene of human influenza A H3N2 viruses isolated in spain from 1996 to 2000

A simple molecular technique was used for the rapid preliminary genetic characterization of human influenza A H3N2 viruses isolated in Spain from 1996 to 2000. Subtyping, based on RT-PCR, was followed by subtype-specific restriction enzyme fragment length polymorphism (RFLP) analyses of an amplified region of the HA1 domain of the H3 haemagglutinin (HA) gene to distinguish variants differentiated by common amino acid substitutions in HA1. The approach was tested using 135 Spanish H3N2 isolates and included nucleotide sequencing and phylogenetic analyses of a region of the HA1 domain of 41 representative isolates. The viruses were distinguished by haemagglutination inhibition (HI) assays into two antigenically discernible groups, the A/Wuhan/359/95-like and A/Sydney/5/97-like viruses. The results of PCR-RFLP analysis allowed a finer classification into five genetic variant subgroups, corresponding to those distinguished by phylogenetic analyses. This rapid, simple and variant-specific procedure could, therefore, be used to rapidly screen clinical specimens prior to more detailed antigenic and genetic analyses.

The evolution of human influenza viruses

The evolution of influenza viruses results in (i) recurrent annual epidemics of disease that are caused by progressive antigenic drift of influenza A and B viruses due to the mutability of the RNA genome and (ii) infrequent but severe pandemics caused by the emergence of novel influenza A subtypes to which the population has little immunity. The latter characteristic is a consequence of the wide antigenic diversity and peculiar host range of influenza A viruses and the ability of their segmented RNA genomes to undergo frequent genetic reassortment (recombination) during mixed infections. Contrasting features of the evolution of recently circulating influenza AH1N1, AH3N2 and B viruses include the rapid drift of AH3N2 viruses as a single lineage, the slow replacement of successive antigenic variants of AH1N1 viruses and the co-circulation over some 25 years of antigenically and genetically distinct lineages of influenza B viruses. Constant monitoring of changes in the circulating viruses is important for maintaining the efficacy of influenza vaccines in combating disease.

Sequential tonometry as a practical method to estimate truncal pulse wave velocity

BACKGROUND

Pulse wave velocity (PWV) is a surrogate marker of arteriosclerosis. It can be measured by recording pressure or flow wave signals at two recording sites of an arterial segment simultaneously or sequentially. However, it is unknown how the values of pulse wave velocity derived from various techniques can be compared. Thus, the aims of the present study were to investigate whether different techniques result in different values of PWV.

METHODS

We measured aortic PWV from 101 uremic and non-uremic patients using both applanation tonometry and Doppler velocimetry by sequential method. To evaluate whether there is a difference between the sequentially and simultaneously derived PWV, simultaneous method using 2 tonometer or 2 Doppler probes was also applied in 50 and 23 subjects, respectively.

RESULTS

There was no significant difference between PWV derived from sequential and simultaneous tonometry (933+/-310 cm/s and 919+/-301 cm/s,p = 0.09). Likewise, there was no significant difference between PWV derived from sequential and simultaneous velocimetry (778+/-241 cm/s and 761+/-205 cm/s,p = 0.35). However, PWV determined by sequential tonometry was significantly greater than (949+/-315 cm/s and 735+/-208 cm/s, respectively,p < 0.001), yet also significantly correlated with that determined by sequential velocimetry (r = 0.83, p < 0.001).

CONCLUSIONS

Sequential applanation tonometry is a practical approach to measure PWV in view of technical convenience and the cost of equipment and manpower. Furthermore, we should be cautious in interpreting PWV derived from different methodologies as greater PWV value might be obtained by applanation tonometry than by Doppler velocimetry.

Association between smoking, acetaldehyde dehydrogenase-2 1-1 status, and alcohol drinking among Taiwanese polyvinyl chloride workers

To study the factors affecting alcohol consumption among Taiwanese workers, we conducted an investigation of the association between alcohol drinking and smoking, aldehyde dehydrogenase-2 (ALDH2) status, alcohol dehydrogenase-2 (ADH2) status, any history of abnormal liver function, and hepatitis B and C viral infection. The subjects included 207 male workers who had been followed-up with respect to liver function periodically since 1992. Information relating to current alcohol consumption and smoking habits was obtained by an interviewer-administered questionnaire in 1996, and any history of liver function and hepatitis B and C virus infection was obtained from previous medical surveillance. Genotypes of ALDH2 and ADH2 were determined by polymerase chain reaction/restriction fragment polymorphism assay. Results have revealed that smoking and ALDH2 1-1 status were associated with current alcohol consumption (respectively: odds ratio, 23.3; P < 0.01 and odds ratio, 14.5; P < 0.05). Neither a history of abnormal liver function nor a history of hepatitis B and/or C infection was associated with current alcohol consumption. It seems that only those with ALDH2 1-1 who are smokers consume alcohol. We conclude that smoking and inherited ALDH2 1-1 are the most important determinants of alcohol consumption. In addition to the medical advice of physicians in their yearly health check-ups, worksite health-promotion programs based on both alcohol consumption habits and smoking cessation should be instituted forthwith, particularly for those who demonstrate the potential for developing liver damage.

Multiple-point variance analysis for optimal adjustment of a monitoring network

The selection of sampling sites is one of the major tasks in the design of a monitoring network. Many environmental networks suffer from either insufficient information or redundant information. This study presents a new, effective algorithm that addresses the issues of insufficient and reduction information. The new algorithm is denoted as Multiple-Point Variance Analysis (MPV). MPV includes both Multiple-Point Variance Reduction Analysis (MPVR) for adding information-effectives sites, and Multiple-Point Variance Increase Analysis (MPVI) for deleting information-redundant sites. The MPVR and MPVI equations are verified under two hypothetical cases. The optimal procedures of this new algorithm include determination of simultaneous additions or deletions of groups of sampling points. These proposed optimization procedures eliminate the need for any spatial discretizations or sequential selections. The efficiency of these optimal procedures is tested under actual field conditions. The results show that the optimal MPV is an effective tool for adjustment of existing sampling networks.

Infection of a child in Hong Kong by an influenza A H3N2 virus closely related to viruses circulating in European pigs

Influenza virus A/Hong Kong/1774/99, isolated from a young child with mild influenza, was shown to be similar in its antigenic and genetic characteristics to H3N2 viruses circulating in pigs in Europe during the 1990s and in particular to be closely related to viruses isolated from two children in the Netherlands in 1993. Similar viruses had previously not been identified outside Europe. Although there is little evidence as to how the child contracted the infection, it appears likely that pigs in southern China were the source of infection. Characteristics shared with the European swine viruses include resistance to the anti-influenza drugs amantadine and rimantadine. Thus not only does this incident once again highlight the potential of pigs as a source of novel human influenza viruses, but also indicates the potential for emergence of amantadine-resistant human viruses.

Effects of bromide on the formation of THMs and HAAs

The role of bromide in the formation and speciation of disinfection by-products (DBPs) during chlorination was investigated. The molar ratio of applied chlorine to bromide is an important factor in the formation and speciation of trihalomethanes (THMs) and halogenacetic acids (HAAs). A good relationship exists between the molar fractions of THMs and the bromide incorporation factor. The halogen substitution ability of HOBr and HOCl during the formation of THMs and HAAs can be determined based on probability theory. The formation of HAAs, and their respective concentrations, can also be estimated through use of the developed model.

Dynamics of changes in micronucleus frequencies in subjects post cessation of chronic low-dose radiation exposure

To assess DNA damage remaining in peripheral lymphocytes, 48 individuals were evaluated twice for lymphocyte micronucleus frequencies by the cytokinesis-blocking cytochalasin B (CBMN) analysis post relocation from radio-contaminated apartments after various periods of time. The frequencies of CBMN at the first evaluation were significantly higher than those at the second examination (Chang et al., 1999c). These individuals were categorized into three groups: those with cumulative exposure of >300 mSv (defined as high exposure, HDose), those with 100-300 mSv (MDose) and those with <100 mSv (LDose). Using the Poisson mixed-effect model (Little et al., 1996), the estimated mean CBMN frequencies ( per thousand) for individuals in HDose, MDose and LDose exposure categories when they had only recently relocated were 21.8, 17.6 and 15.4, respectively. The estimated mean duration post relocation for the CBMN frequencies of these individuals to reduce to 10.2, the second CBMN frequency, on average, was 47.5, 37.2 and 28.3 months in the three exposure groups, respectively. The rates of change in CBMN frequencies were shown to be significantly higher in the HDose group than in the MDose and LDose groups. The results suggested a characteristic dose-dependent decline in the CBMN frequencies in the exposed population post cessation of chronic low-dose ionizing radiation exposure.

Antigenic and genomic relation between human influenza A (H3N2) viruses circulating in Argentina during 1998 and the H3N2 vaccine component

OBJECTIVE

Due to the lack of correlation from 1994 to 1997 between the A H3N2 component of the influenza vaccine recommended for this period and the circulating viruses in Argentina, we decided to study the antigenic and genomic relationships of the 1998 A H3N2 Argentine circulating strains with the corresponding vaccine component for that year as recommended by the World Health Organization (WHO).

METHODS

We selected 18 influenza A H3N2 strains isolated in Argentina during 1998 to carry out an antigenic and genomic study of their hemagglutinin (HA) and neuraminidase (NA) proteins. For the genomic study we added 3 isolates from Uruguay. We compared the Argentine and Uruguayan strains with available reference strains.

RESULTS

We found that all 18 strains from Argentina were similar to the A/Sydney/5/97 (H3N2) strain, as opposed to the A/Wuhan/359/95 (H3N2) strain, which was the vaccine component. This result was confirmed by the genomic study.

CONCLUSIONS

The approach that we applied in Argentina has improved the quality and quantity of information about influenza in the country. This type of work should be encouraged in other countries in order to help choose the most appropriate vaccine components each year and provide individuals with the best possible protection against influenza.

Physical heights of children with prolonged low dose-rate gamma-radiation exposure in radiocontaminated buildings

PURPOSE

To evaluate low dose-rate radiation effects on the physical heights of children staying in apartments with 60Co-contaminated steel construction.

MATERIALS AND METHODS

Children who once resided in radiocontaminated apartments since early 1983 were examined for height and body weight status from age 1 month to 18 years and before they moved out of the apartments. The physical heights and body weights of 21 898 age- and sex-matched non-exposed children from a nationwide school surveillance in 1997-98 were taken as controls. The physical height data were shown as height percentiles (HP) compared with reference children and age-specific relative height differences (RHD).

RESULTS

HP and RHD in 48 exposed boys and 37 girls were analysed using generalized estimating equations (GEE), which accounted for multiple measurements and correlation between these measurements in the same individuals during this period. After adjusting for effects from parental heights and body mass index (BMI), clear dose-related decreases in HP and RHD were observed in the exposed boys with a cumulative exposure > 60 mSv.

CONCLUSIONS

Prolonged low dose-rate y-radiation exposure was associated with adverse effects on the physical heights of growing boys, but were less apparent in the exposed girls.

HUman MicroNucleus project: international database comparison for results with the cytokinesis-block micronucleus assay in human lymphocytes: I. Effect of laboratory protocol, scoring criteria, and host factors on the frequency of micronuclei

Micronucleus (MN) expression in peripheral blood lymphocytes is well established as a standard method for monitoring chromosome damage in human populations. The first results of an analysis of pooled data from laboratories using the cytokinesis-block micronucleus (CBMN) assay and participating in the HUMN (HUman MicroNucleus project) international collaborative study are presented. The effects of laboratory protocol, scoring criteria, and host factors on baseline micronucleated binucleate cell (MNC) frequency are evaluated, and a reference range of "normal" values against which future studies may be compared is provided. Primary data from historical records were submitted by 25 laboratories distributed in 16 countries. This resulted in a database of nearly 7000 subjects. Potentially significant differences were present in the methods used by participating laboratories, such as in the type of culture medium, the concentration of cytochalasin-B, the percentage of fetal calf serum, and in the culture method. Differences in criteria for scoring micronuclei were also evident. The overall median MNC frequency in nonexposed (i.e., normal) subjects was 6.5 per thousand and the interquartile range was between 3 and 12 per thousand. An increase in MNC frequency with age was evident in all but two laboratories. The effect of gender, although not so evident in all databases, was also present, with females having a 19% higher level of MNC frequency (95% confidence interval: 14-24%). Statistical analyses were performed using random-effects models for correlated data. Our best model, which included exposure to genotoxic factors, host factors, methods, and scoring criteria, explained 75% of the total variance, with the largest contribution attributable to laboratory methods.

H9N2 subtype influenza A viruses in poultry in pakistan are closely related to the H9N2 viruses responsible for human infection in Hong Kong

Following the outbreak of H5N1 "bird flu" in Hong Kong in 1997, the isolation of H9N2 subtype viruses from patients in southern China and Hong Kong SAR once again raised the spectre of a possible influenza pandemic. H9N2 viruses have recently been responsible for disease in poultry in various parts of the world and preliminary studies of the H9 haemagglutinin (HA) genes of viruses isolated during 1998 and 1999 in Germany, Iran, Pakistan, and Saudi Arabia showed a close relationship to the HA genes of the viruses that infected two children in Hong Kong SAR. Analysis of the complete genome of a Pakistan isolate, A/chicken/Pakistan/2/99, showed that it is closely related in all eight genes (97-99% homology) to the human H9N2 isolates and furthermore that the six genes encoding internal components of the virus are similar to the corresponding genes of the H5N1 viruses that caused 6 (out of 18) fatal cases of human infection. Thus H9N2 viruses similar to those that caused human infections in Hong Kong are circulating more widely in other parts of the world. Whether or not these H9N2 viruses also have features that facilitate avian-to-human transmission is not known. Since avian H9N2 viruses are currently perceived to represent a significant threat to human health it is important to determine whether or not viruses of this subtype circulating in poultry in various parts of the world have the potential to infect people.

Increased arterial wave reflection may predispose syncopal attacks

BACKGROUND

The incidence of syncope increases with age, while aging is also associated with increased arterial wave reflection.

HYPOTHESIS

The study was undertaken to determine whether increased arterial wave reflection is a predisposing factor of syncope.

METHODS

We recruited 38 patients (28 men and 10 women, mean age 57.2 +/- 20.3 years, range 17-87 years) with a history of syncope within 6 months of entry. The etiology of syncope was documented for each patient by a complete assessment of vasomotor function and cerebral flow. All patients received a comprehensive echocardiographic evaluation of cardiac structure and function. Carotid augmentation index (AI) was estimated noninvasively with the tonometry technique. The results were compared with those from 54 age- and gender-matched controls.

RESULTS

The most frequent diagnoses of syncope were postural hypotension (13 patients) and cerebrovascular dysautoregulation (10 patients), and the cause could not be determined in 9 patients. Compared with the control group, the syncope group had a greater AI (20 +/- 21 vs. 10 +/- 15%, p = 0.013). Subgroup analysis of 20 patients aged > 50 years and with the aforementioned diagnoses showed even more striking results: AI, 29 +/- 10 vs. 11 +/- 15%, p < 0.001. The enhanced augmentation in the patients remained when age, systolic blood pressure, height, and heart rate were accounted for. Analysis of the carotid pulse wave suggested that both the timing and intensity of wave reflection were enhanced in patients with a history of syncope compared with controls.

CONCLUSIONS

Our results support the hypothesis that enhanced arterial wave reflection is associated with the occurrence of syncope, especially in the elderly.

Spiral computed tomographic angiography--a new technique for evaluation of vascular access in hemodialysis patients

Spiral computed tomographic angiography (CTA), a new noninvasive imaging technique, was used to study 10 arteriovenous fistulas (AVF) in 9 hemodialysis patients. Digital subtraction angiography (DSA) was also performed as a gold standard for comparison. AVF stenosis was graded by a four-point scale: grade 0, well patency of supplying artery, anastomosis and drainage vein; grade 1, < 50% stenosis; grade 2, 50-70% stenosis; grade 3, 70-99% stenosis, and grade 4, total occlusion. We found CTA correlated closely to DSA in detecting both stenosis and dilatation of AVF and it spared all the shortcomings of DSA. CTA has the potential to be alternative for imaging of dialysis fistulas. Further studies will be performed to specify the role of CTA images in the assessment of the hemodialysis vascular access.

Avian-to-human transmission of H9N2 subtype influenza A viruses: relationship between H9N2 and H5N1 human isolates

In 1997, 18 cases of influenza in Hong Kong (bird flu) caused by a novel H5N1 (chicken) virus resulted in the deaths of six individuals and once again raised the specter of a potentially devastating influenza pandemic. Slaughter of the poultry in the live bird markets removed the source of infection and no further human cases of H5N1 infection have occurred. In March 1999, however, a new pandemic threat appeared when influenza A H9N2 viruses infected two children in Hong Kong. These two virus isolates are similar to an H9N2 virus isolated from a quail in Hong Kong in late 1997. Although differing in their surface hemagglutinin and neuraminidase components, a notable feature of these H9N2 viruses is that the six genes encoding the internal components of the virus are similar to those of the 1997 H5N1 human and avian isolates. This common feature emphasizes the apparent propensity of avian viruses with this genetic complement to infect humans and highlights the potential for the emergence of a novel human pathogen.

Persistent leucocyte abnormalities in children years after previous long-term low-dose radiation exposure

Two hundred and eighty-nine children who had been educated in a kindergarten during 1983-92 and received continuous low-dose whole body gamma-irradiation from 60Co-contaminated steel window frames in their classrooms were investigated for residual effects on their haematological tissues. Another 751 children, sex and age-matched, received similar but much lower exposure in an elementary school with classrooms built with contaminated steel rebars. The peripheral leucocytes of these children were examined 5-7 years after they had stopped using these irradiated classrooms. Children who received higher exposure in the kindergarten were shown to have a significant decrease in total leucocytes and neutrophils and an increase in eosinophils. Moreover, they were shown to be at significantly higher risk of developing relative leucopenia and neutropenia, but not lymphocytopenia, than those who received a lower exposure at the elementary school. Children from the kindergarten who had much higher exposure were shown to have a significant lowering of total leucocytes and neutrophils, and an increase in eosinophils years after exposure. Residual adverse haematological effects on the exposed children are strongly suspected.

Follow-up in the micronucleus frequencies and its subsets in human population with chronic low-dose gamma-irradiation exposure

Forty-eight individuals, who received protracted low-dose rate gamma-irradiation from radioactive environments for 2-10 years, have been evaluated repetitively for cytogenetic damage by the cytochalasin-B micronuclei assay (CBMN) after they relocated from radioactive buildings. These subjects were shown to have a significant decrease in the CBMN frequencies during 26.2+/-8.4 months of follow-up. By the mixed effect multiple linear regression analysis, the CBMN frequencies in these 48 subjects during repetitive measurements were significantly associated with the relocation duration since leaving the radioactive environments (relocation time or RT in months; estimate -0.47, standard error 0. 0016, p value 0.0074). The alteration rate in the proportions of binucleates carrying a single micronucleus and those with multiple micronuclei was further compared among 26 of these exposed individuals. The proportions of binucleates with multi-micronuclei were shown to decline significantly faster than those with a mono-micronucleus between these two repetitive assays (proportional Z-test, p value 0.003). Moreover, some of the exposed subjects were shown to have a persistent increase in the total micronuclei frequencies or carrying multi-micronuclei in the binuclei even 3-4 years post-cessation of exposure. This suggests potential genomic instability in stem cells of the exposed individuals and the phenomenon deserves further closer monitoring. Understanding the dynamics of micronucleus expression in lymphocytes in subjects with previous mutagenic exposure would be of significant importance for human population monitoring.

Change in centromeric and acentromeric micronucleus frequencies in human populations after chronic radiation exposure

Acute radiation exposure of humans was observed to induce various forms of cytogenetic damage, including increased frequencies of micronuclei and chromosomal aberrations. However, the cytogenetic effects of chronic low dose radiation exposure in vivo needs further characterization. Sixteen subjects with chronic low dose rates of gamma-radiation exposure from 60Co-contaminated steel in radioactive buildings were compared with seven non-exposed reference subjects for micronucleus frequencies after they relocated. By in situ hybridization using a digoxigenin-labeled anti-alpha all human centromere probe, the exposed subjects were shown to have a significant increase in cytochalasin B-modulated micronucleus (CBMN) frequencies, as well as a significant increase in centromere-positive (C+) CBMN, centromere-negative (C-) CBMN, total C+signals, single C+ MN signals and multiple C+ signals/1000 binucleated cells (BN). However, decreases in the ratios C+MN/C- MN and C+MN/total CBMN (%) were also noted in the exposed subjects. By mixed effects analysis, considering individuals from the same families, the C- MN and single C+ MN/1000 BN were both positively and moderately associated with previous cumulative exposure. When the time period of relocation post-exposure (relocation time or RT) was considered, total C+MN and multiple C+MN/1000 BN were negatively and significantly associated with RT. Moreover, the C+MN, C- MN, C+MN/C- MN ratio and single C+MN/1000 BN were all negatively and moderately associated with RT, but not with exposure dose. This suggested that acentromeric and single or multiple centromeric CBMN cytogenetic damage seems to disappear differentially in human subjects post chronic low dose radiation exposure.

Chinese herbal medicine, sibship, and blood lead in children

OBJECTIVES

Risk factors for increased blood lead concentration (BPb) has been investigated. However, the effect of sibship and Chinese herbal medicine on BPb has not been systematically studied. In this study BPb data from voluntary testing was used to determine if Chinese herbal medicine and sibship were associated with BPb.

METHODS

319 children aged 1-7 were tested for BPb. Meanwhile, parents were interviewed to obtain information including consumption of Chinese herbal medicine, living environment, lifestyle, and sibship of the children tested.

RESULTS

The mean (SD) BPb of 319 preschool children was 4.4 (2.4) micrograms/dl. The consumption of Ba-baw-san (a Chinese herbal medicine) was significantly associated with increased BPb in children (p = 0.038). Further multivariate regression analysis of BPb in 50 pairs of siblings showed the factors of being brothers explained 75% of variation for BPb, and being sisters and brother-sister explained 51% and 41% of variation respectively.

CONCLUSION

Chinese herbal medicine and children's play patterns within the family expressed in different types of sibship are the main determinants of low concentrations of BPb in preschool children of Taiwan.

Studies of the binding properties of influenza hemagglutinin receptor-site mutants

Site-specific mutations have been made in the influenza hemagglutinin (HA) receptor binding site to assess the contribution of individual amino acid residues to receptor recognition. Screening of mutant HAs, expressed using recombinant vaccinia virus-infected cells, for their abilities to bind human erythrocytes indicated that substitutions involving conserved residues Y98F, H183F, and L194A severely restricted binding and that the substitution W153A prevented cell surface expression of HA. Mutation of residues E190 and S228 that are in positions to form hydrogen bonds with the 9-OH of sialic acid appeared to increase erythrocyte binding slightly, as did the substitution G225R. Substitutions of other residues that are directly or indirectly involved in receptor binding, S136T, S136A, Y195F, G225D, and L226P, had intermediate effects on binding between these two extremes. Estimates of changes in receptor binding specificity based on inhibition of binding to erythrocytes by nonimmune horse sera indicated that mutants G225R and L226P, unlike wild-type HA, were not inhibited; Y195F and G225D mutants were, like wild type, inhibited; and erythrocyte binding by mutants S136A, S136T, E190A, and S228G was only partially inhibited. Viruses containing mutant HAs Y98F, S136T, G225D, and S228G that cover the range of erythrocyte binding properties observed were also constructed by transfection. All four transfectant viruses replicated in MDCK cells and embryonated hens' eggs as efficiently as wild-type X-31 virus, although the Y98F mutant virus was unable to agglutinate erythrocytes. Mutant MDCK cells that have reduced levels of cell surface sialic acids were susceptible to infection by S136T, G225D, and S228G transfectant viruses and by wild type but not by the Y98F transfectant virus.

[A new dynamic model of release for not-corroded drug system--revision and use of Fick's first law]

Based on the facts that the diffusion coefficient in original Fick's first law is not a strict constant but changes with concentration and that the original Fick's first law is only suitable for the stable diffusion with constant concentration gradient but many experiments have shown that the concentration gradient is a function of time. The authors suggest that the diffusion coefficient and the concentration gradient should be revised, respectively, as a concentration function and a time function. That is, [formula: see text] So, the Fick's first law is revised as [formula: see text] In the formula, dW/dt represents the rate of diffusion. D0 is the intrinsic diffusion coefficient that is a constant only concerning the temperature and the character of the substance diffused. A is the area of diffusion surface, alpha is the constant concerning the change of concentration gradient, C0 and C is, respectively, the concentration on the diffusion surface at time t0 and any time t. Based on this, the dynamic model of release on the preparations not-corroded is derived: [formula: see text] Here, k0 is the release constant concerning D0, temperature, C0 and A. The model gave better results than other models in common use for simulating the release dynamic process and the physical meanings of the model parameters are explicit.

Absence of modulating effects of cytokines on antioxidant enzymes in peritoneal mesothelial cells

OBJECTIVE

To investigate the modulation of superoxide dismutase, glutathione peroxidase, and catalase by cytokines and endotoxin in human peritoneal mesothelial cells.

DESIGN

Cultured human peritoneal mesothelial cells were treated with various concentrations of interleukin-1 alpha, tumor necrosis factor-alpha (TNF-alpha), interleukin-6, interleukin-8, transforming growth factor-beta (TGF beta), and lipopolysaccharide. Cell morphology was observed and the activities of superoxide dismutase, catalase, and glutathione peroxidase were assayed. The antioxidant enzyme activities of human peritoneal mesothelial cells were also compared with those of human liver and kidney tissues.

RESULTS

Interleukin-1 alpha, TNF alpha, TGF beta, and lipopolysacharide caused dose-dependent cytotoxicities in mesothelial cells. The activities of these three antioxidant enzymes did not change after treatment with cytokines and endotoxin. The total superoxide dismutase activity of confluent human peritoneal mesothelial cells was found to be greater than that of human liver and kidney tissues and was composed mostly of manganese superoxide dismutase activity. Furthermore, glutathione peroxidase and catalase activities of human peritoneal mesothelial cells were lower than those of human liver and kidney tissues.

CONCLUSION

In human peritoneal mesothelial cells, lack of induction of antioxidant enzymes by inflammatory cytokines, as well as high superoxide dismutase activity accompanied by insufficient glutathione peroxidase and catalase activities may both contribute to the susceptibility of these cells to oxidative damage. Therefore, appropriate management to decrease oxidative injury to the peritoneum should be taken into consideration when treating long-term continuous ambulatory peritoneal dialysis patients.