Scaling and nonscaling finite-size effects in the Gaussian and the mean spherical model with free boundary conditions

We calculate finite-size effects of the Gaussian model in a Lx(d-1) box geometry with free boundary conditions in one direction and periodic boundary conditions in d-1 directions for 2<d<4. We also consider film geometry (L--> infinity ). Finite-size scaling is found to be valid for d<3 and d>3 but logarithmic deviations from finite-size scaling are found for the free energy and energy density at the Gaussian upper borderline dimension d*=3. The logarithms are related to the vanishing critical exponent 1-alpha-nu=(d-3)/2 of the Gaussian surface energy density. The latter has a cusplike singularity in d>3 dimensions. We show that these properties are the origin of nonscaling finite-size effects in the mean spherical model with free boundary conditions in d > or =3 dimensions. At bulk T(c), in d=3 dimensions we find an unexpected nonlogarithmic violation of finite-size scaling for the susceptibility chi approximately L3 of the mean spherical model in film geometry, whereas only a logarithmic deviation chi approximately L2 ln L exists for box geometry. The result for film geometry is explained by the existence of the lower borderline dimension d(l)=3, as implied by the Mermin-Wagner theorem, that coincides with the Gaussian upper borderline dimension d*=3. For 3<d<4 we find a power-law violation of scaling chi approximately L(d-1) at bulk T(c) for box geometry and a nonscaling temperature dependence chi(surface) approximately xi(d) of the surface susceptibility above T(c). For 2<d<3 dimensions we show the validity of universal finite-size scaling for the susceptibility of the mean spherical model with free boundary conditions for both box and film geometry and calculate the corresponding universal scaling functions for T > or =T(c).

Nonuniversal size dependence of the free energy of confined systems near criticality

The singular part of the finite-size free-energy density f(s) of the O(n) symmetric phi(4) field theory is calculated for confined geometries of linear size L with periodic boundary conditions in the large-n limit and with Dirichlet boundary conditions in one-loop order. We find that both a sharp cutoff and a subleading long-range interaction cause a leading nonuniversal L dependence of f(s) near T(c). This implies a significant restriction for the validity of universal finite-size scaling for model systems and real systems. For film geometry we predict a leading nonuniversal contribution to the critical Casimir force above the superfluid transition of (4)He.

Topical application of penciclovir cream for the treatment of herpes simplex facialis/labialis: a randomized, double-blind, multicentre, aciclovir-controlled trial

BACKGROUND

Herpes simplex facialis/labialis (HSFL) is a common infectious skin disorder, caused mainly by herpes simplex virus (HSV) type 1, for which the topical application of a cream containing an antiviral agent for treatment of the disease has been widely utilized.

OBJECTIVE

To explore the efficacy of the topical application of 1% penciclovir cream in the treatment of HSFL, and to compare its efficacy and safety with 3% aciclovir cream.

METHODS

A total of 248 patients with a diagnosis of HSFL were randomly allocated to one of the two treatment groups (n = 124 each), using stratified randomization based on a table of random numbers. Before treatment (day 0) and at every visit (days 3, 5 and 7) during the study, the sign and symptom scores were recorded by the same doctor.

RESULTS

Excluding 23 patients (10 in the penciclovir and 13 in the aciclovir groups), 225 completed the study, and no severe adverse events were noted with any of the treatment regimens. Results show that an encouraging improvement in the clinical course was found simultaneously for patients with each episode type and each treatment assignment. There were no significant differences in terms of efficacy endpoint, clinical cure rate, and safety between the two treatment arms, but there was a trend towards a shorter time to resolution of all symptoms, cessation of new blisters, and loss of crust (p <or= 0.08) in penciclovir-treated primary patients. In addition, the clinical scores in penciclovir-treated primary patients were significantly lower than those in the respective aciclovir-treated patients on treatment day 5 (p < 0.01) and day 7 (p < 0.05).

CONCLUSION

Topical 1% penciclovir cream is as convenient and as effective as 3% aciclovir cream for the treatment of HSFL. Penciclovir cream may provide a good topical alternative to other types of therapy in the future.

Epitope mapping using the X-ray crystallographic structure of complement receptor type 2 (CR2)/CD21: identification of a highly inhibitory monoclonal antibody that directly recognizes the CR2-C3d interface

Complement receptor type 2 (CR2)/CD21 is a B lymphocyte cell membrane C3d/iC3b receptor that plays a central role in the immune response. Human CR2 is also the receptor for the EBV viral membrane glycoprotein gp350/220. Both C3d and gp350/220 bind CR2 within the first two of 15-16 repetitive domains that have been designated short consensus/complement repeats. Many mAbs react with human CR2; however, only one currently available mAb is known to block both C3d/iC3b and gp350/220 binding. We have used a recombinant form of human CR2 containing the short consensus/complement repeat 1-2 ligand-binding fragment to immunize Cr2(-/-) mice. Following fusion, we identified and further characterized four new anti-CR2 mAbs that recognize this fragment. Three of these inhibited binding of CR2 to C3d and gp350/220 in different forms. We have determined the relative inhibitory ability of the four mAbs to block ligand binding, and we have used overlapping peptide-based approaches to identify linear epitopes recognized by the inhibitory mAbs. Placement of these epitopes on the recently solved crystal structure of the CR2-C3d complex reveals that each inhibitory mAb recognizes a site either within or adjacent to the CR2-C3d contact site. One new mAb, designated 171, blocks CR2 receptor-ligand interactions with the greatest efficiency and recognizes a portion of the C3d contact site on CR2. Thus, we have created an anti-human CR2 mAb that blocks the C3d ligand by direct contact with its interaction site, and we have provided confirmatory evidence that the C3d binding site seen in its crystal structure exists in solution.

Studies on mode of detection of leprosy in China during the years 1981-1998

Along with the nationwide economic reform initiated in the early 1980s and the rapid decrease of leprosy endemic after the implementation of multi-drug therapy (MDT), the leprosy programme changed from 'vertical' to 'horizontal'. An evolution in the mode of detection of leprosy cases has consequently taken place. Based on the nationwide registration of newly detected cases, the profile of patients at detection has been studied. The proportions of cases corrected significantly with calendar years in detection by dermatological clinics, contact checks, 'clue survey' and mass survey, showing a significant increase in percentage of cases detected through dermatological clinics and contact checks, and decreases through 'clue survey' and mass survey. Detection of cases through dermatological clinics and voluntary reporting have become the main modes of case-finding during 1997-1998, accounting for 37.3% and 28.6%, respectively, where contact check accounts for only 9.1%. In areas with good dermatological services, a significantly higher proportion (75.9%) of cases was detected through dermatological clinics, where voluntary reporting and 'clue survey' were the main modes of detection in endemic areas. As regards confirmation of diagnosis, the great majority of cases were confirmed by leprosy units, even though they were detected in various other situations. Only 6.5% of leprosy cases were detected and subsequently confirmed by doctors in dermatologic clinics. The present modes of detection and their relation to demographical, epidemiological, clinical factors and health services are discussed. This study emphasizes the cardinal importance of the dermatological clinics in the detection of leprosy cases in China at the present time and hence the need to strengthen the training of doctors in these clinics, while continuously encourage their involvement in leprosy control.

Evaluation of diagnostic criteria for atopic dermatitis: validity of the criteria of Williams et al. in a hospital-based setting

BACKGROUND

Surveys of the prevalence of atopic dermatitis (AD) have been carried out world-wide, but the results vary widely. The differences probably result from the use of different diagnostic criteria. Williams et al. proposed minimum, simplified, diagnostic criteria that require no invasive test and are easy to use. Pilot studies in European countries showed their suitability for implementation both in hospitals and in the community, and their high sensitivity and specificity.

OBJECTIVES

To evaluate the potential practical value of the criteria of Williams et al. in the Chinese population.

METHODS

The criteria of Hanifin and Rajka (gold standard), Williams et al. and Kang and Tian were applied and compared in 111 patients with AD and 121 control subjects with other skin diseases in three out-patient centres in China.

RESULTS

The criteria of Williams et al. showed a similar diagnostic efficiency to that of the gold standard, with the sensitivity, specificity and kappa value reaching 95.50%, 97.52% and 0.93, respectively. No significant difference was found between the criteria of Williams et al. and those of Kang and Tian (chi2 = 0.69, P > 0.05). 'Onset under the age of 2 years', a criterion of Williams et al. could be used in subjects of any age.

CONCLUSIONS

The diagnostic efficiency of the criteria of Williams et al. was basically similar to those of Hanifin and Rajka and of Kang and Tian in our out-patient settings. However, those of Williams et al. were easier to apply and required no invasive tests.

[Role of STAT1 on the regulation the human hsp90 alpha gene expression]

OBJECTIVE

To investigate the role of STAT1 on the regulation of human hsp90 alpha gene expression.

METHODS

We first transfected Jurkat cells with the STAT1 expression construct and analyzed the expression of hsp90 alpha gene expression via quantitative RT-PCR system. Then we co-transfected the STAT1 expression construct and the CAT reporter gene driven by different length of 5' flanking sequence of hsp90 alpha gene. Western blot was carried out to detect the level of tyrosine phosphorylation in Jurkat cells with and without heat shock treatment (42 degrees C 1 h). By electrophoretic mobility shift assays (EMSA), we evaluated the DNA binding activity of a STAT1 responsible element located in the regulatory region of hsp90 alpha gene in Jurkat cell nuclear extracts.

RESULTS

The mRNA level of hsp90 alpha gene in Jurkat cells was decreased when transfected by STAT1 expression construct, over-expression of STAT1 down-regulates the expression of CAT reporter gene with the present of a distal fragment from -1756 to -1463 within the 5' flanking regulatory sequences of hsp90 alpha gene. The tyrosine phosphorylation of STAT1 was detectable in Jurkat cells and increased when subjected to heat shock. Electrophoretic mobility shift assays (EMSA) results showed that STAT1 could bind to its responsible element in the regulatory region of hsp90 alpha gene.

CONCLUSION

STAT1 could negatively regulate the human hsp90 alpha gene expression.

Strange quark polarization of the nucleon: a parameter-independent prediction of the chiral potential model

We perform a one-loop calculation of the strange quark polarization (Deltas) of the nucleon in an SU(3) chiral potential model. We find that if the intermediate quark excited states are summed over in a proper way, i.e., summed up to a given energy instead of given radial and orbital quantum numbers, Deltas turns out to be almost independent of all the model parameters: quark masses and potential strengths. The contribution from the quark-antiquark pair creation and annihilation " Z" diagrams is found to be significant. Our numerical results agree quite reasonably with experiments and lattice QCD calculations.

Structure of complement receptor 2 in complex with its C3d ligand

Complement receptor 2 (CR2/CD21) is an important receptor that amplifies B lymphocyte activation by bridging the innate and adaptive immune systems. CR2 ligands include complement C3d and Epstein-Barr virus glycoprotein 350/220. We describe the x-ray structure of this CR2 domain in complex with C3d at 2.0 angstroms. The structure reveals extensive main chain interactions between C3d and only one short consensus repeat (SCR) of CR2 and substantial SCR side-side packing. These results provide a detailed understanding of receptor-ligand interactions in this protein family and reveal potential target sites for molecular drug design.

Papillomavirus capsid protein expression in Escherichia coli: purification and assembly of HPV11 and HPV16 L1

The L1 major capsid proteins of human papillomavirus (HPV) types 11 and 16 were purified and analyzed for structural integrity and in vitro self-assembly. Proteins were expressed in Escherichia coli as glutathione-S-transferase-L1 (GST-L1) fusions and purified to near homogeneity as pentamers (equivalent to viral capsomeres), after thrombin cleavage from the GST moiety and removal of tightly associated GroEL protein. Sequences at the amino and carboxy termini contributing to formation of L1 pentamers and to in vitro capsid assembly were identified by deletion analysis. For both HPV11 and HPV16 L1, up to at least ten residues could be deleted from the amino terminus (Delta N10) and 30 residues from the carboxy terminus (Delta C30) without affecting pentamer formation. The HPV16 pentamers assembled into relatively regular, 72-pentamer shells ("virus-like particles" or VLPs) at low pH, with the exception of HPV16 L1 Delta N10, which assembled into a 12-pentamer, T=1 capsid (small VLP) under all conditions tested. The production of large quantities of assembly-competent L1, using the expression and purification protocol described here, has been useful for crystallographic analysis, and will be valuable for studies of virus-receptor interactions and potentially for vaccine design.

Inhibition of hepatitis B virus by oxymatrine in vivo

AIM: To investigate the anti-HBV effect of oxymatrine (oxy) in vivo.

METHODS: HBV transgenic mice were produced by micro-injection of a 4.2 kb fragment containing the complete HBV genomes. Expression level of HBsAg and HBcAg in the transgenic mice liver was determined by immunohistochemical assay.

RESULTS: Four groups (6 mice in each group) were injected intraperitoneally with oxy at the dosage of 100, 200, and 300 mg/kg or with saline once a day for 30 d. Both HBsAg and HBcAg were positive in livers of all the six mice in the control group (injected with saline), and were positive in livers of two mice in 100 mg/kg group and 300 mg/kg group. In 200 mg/kg group, HBsAg and HBcAg were negative in livers of all the six mice. Based on the results, 200 mg/kg is the ideal dosage to explore the effect of oxy at different time points. According to the oxy treatment time, mice were divided into four groups: 10 d, 20 d, 30 d and 60 d (4 mice in each group). Each mouse underwent liver biopsy two weeks before the treatment of oxy. Down-regulation of HBsAg and HBcAg appeared after treatment of oxymatrine for 10 d and 20 d, Dane-like particles disappeared after the treatment of oxy for 20 d under electron microscopy, however, the expression level of HBsAg and HBcAg returned to normal 60 d later after oxy treatment.

CONCLUSION: oxymatrine can reduce the contents of HBsAg and HBcAg in transgenic mice liver,longer treatment time and larger dosage do not yield better effects.

The N-terminal "beta-barrel" domain of 5-lipoxygenase is essential for nuclear membrane translocation

5-Lipoxygenase is the key enzyme in the formation of leukotrienes, which are potent lipid mediators of asthma pathophysiology. This enzyme translocates to the nuclear envelope in a calcium-dependent manner for leukotriene biosynthesis. Eight green fluorescent protein (GFP)-lipoxygenase constructs, representing the major human and mouse enzymes within this family, were constructed and their cDNAs transfected into human embryonic kidney 293 cells. Of these eight lipoxygenases, only the 5-lipoxygenase was clearly nuclear localized and translocated to the nuclear envelope upon stimulation with the calcium ionophore. The N-terminal "beta -barrel" domain of 5-lipoxygenase, but not the catalytic domain, was necessary and sufficient for nuclear envelope translocation. The GFP-N-terminal 5-lipoxygenase domain translocated faster than GFP-5-lipoxygenase. beta-Barrel/catalytic domain chimeras with 12- and 15-lipoxygenase indicated that only the N-terminal domain of 5-lipoxygenase could carry out this translocation function. Mutations of iron atom binding ligands (His550 or deletion of C-terminal isoleucine) that disrupt nuclear localization do not alter translocation capacity indicating distinct determinants of nuclear localization and translocation. Moreover, data show that GFP-5-lipoxygenase beta-barrel containing constructs can translocate to the nuclear membrane whether cytoplasmic or nuclear localized. Thus, the predicted beta-barrel domain of 5-lipoxygenase may function like the C2 domain within protein kinase C and cytosolic phospholipase A(2) with unique determinants that direct its localization to the nuclear envelope.

Universality and straight phi(4) theory of finite-size effects above the upper critical dimension

We analyze finite-size effects in a L(d) geometry above the upper critical dimension d=4 within the O(n) symmetric straight phi(4) theory on the basis of exact results for n-->infinity and one-loop results for n=1. We show that finite-size effects of the straight phi(4) continuum theory with a smooth (rather than sharp) cutoff belong to the same universality class as those of the straight phi(4) lattice theory. Our analysis predicts both universal and nonuniversal features of finite-size effects and resolves long-standing discrepancies in earlier analyses of Monte Carlo (MC) data for the d=5 Ising model. Our estimates of two fundamental length scales xi(0) and l(0) are confirmed by very recent MC data.

Leprosy in China: epidemiological trends between 1949 and 1998

OBJECTIVE

To report the epidemiological trends of leprosy in China from 1949 to 1998.

METHOD

Data for the study were obtained from the computerized database of the National System of Leprosy Surveillance.

FINDINGS

A total of 474,774 leprosy patients were detected during this 50-year period. Case detection rates per 100,000 population were highest in the 1950s and 1960s, with peaks appearing in 1957-58, 1963-66, 1969-70, and 1983-84, corresponding to mass surveys or screening surveys carried out in most areas or selected areas of the country. While the duration of the disease at the time of detection fell over the period, the disability rates, which were > 50% in the early 1950s, have decreased gradually to 20.8% by 1997-98 but are still too high. More than 50% of cases were found through active methods in the periods 1955-58, 1965-66, and 1969-76, but in recent years cases are mostly detected through dermatological clinics or by voluntary reporting. The peak prevalences of the 1960s (i.e. > 2 per 10,000 population) decreased annually from the 1970s onwards. By the end of 1998 the prevalence was 0.05 per 10,000 population.

CONCLUSIONS

This study shows that leprosy was well controlled in China and that the WHO goal of elimination of leprosy as a public health problem has been achieved at the national and subnational levels. However, leprosy is still unevenly distributed in the country. According to the criterion for leprosy elimination in China--defined as a prevalence of < 1 per 100,000 in county or city--there are still more than 10% of counties or cities where this target has not yet been reached. Special attention must therefore be given to achieve elimination and final eradication of leprosy in China.

Chemical constituents of Typhonium giganteum Engl

A new cerebroside, named typhonoside (1), was isolated from the root tuber of Typhonium giganteum Engl. along with three known compounds dipalmitin (2), alpha-monopalmitin (3) and 2,6-diamino-9-beta-D-ribofuranosylpurine (4). The structure of 1 was determined to be 1-O-beta-D-glucopyranosyl-(2S,3S,4R,8Z)-2-[(2'-hydroxyl-docosanoyl)amino]-8-otadecene-1,3,4-triol on the basis of spectral data.

A comparison of topical application of penciclovir 1% cream with acyclovir 3% cream for treatment of genital herpes: a randomized, double-blind, multicentre trial

Genital herpes simplex virus (HSV) infection, a sexually transmitted disease (STD), is the commonest cause of ulcerative genital infections among the young and adult population. The significant association of genital ulceration and transmission of human immunodeficiency virus (HIV) has been shown in many studies. To explore the potential efficacy of topical treatment of genital herpes with penciclovir cream, a randomized, double-blind, multicentre, acyclovir-controlled Phase II clinical trial of penciclovir 1% cream 5 times daily up to 7 days for suppression of genital herpes was conducted in China. A total of 205 patients aged 20-59 years (mean age 36.0+/-8.8 years for acyclovir and 34.8+/-8.4 years for penciclovir) with a clinical diagnosis of genital herpes were randomly allocated to one of the 2 parallel treatment groups and used for analysis. Clinical assessment were made before treatment and followed up at every visit during the study. Our results show that there was an encouraging improvement simultaneously in the 2 groups although no significant differences in clinical efficacy with respect to clinical cure rate, and times to healing, resolution of all symptoms, absence of blisters, cessation of new blisters, crusting, and loss of crust between penciclovir and acyclovir groups in terms of primary, non-primary and total patients were found. However a significantly shorter time to crusting was found in primary penciclovir group when compared with primary acyclovir group. Adverse experience was generally infrequent and mild, and was comparable in the 2 treatment groups. Based on these preliminary clinical findings, further evaluation of penciclovir 3% cream for topical treatment of genital herpes is planned.

Leprosy in children: a retrospective study in China, 1986-1997

Leprosy in children forms an important link in the natural evolution and the epidemic profile of the disease. The study was undertaken on 1208 child cases detected during the years 1986-1997 in China. The number of child cases constituted 3-4 per cent of the total during this period although the incidence rates decreased dramatically. The detection rate significantly increased with age, and the average rate of 0.027 per 100,000 population was much lower than that in adults. In the pediatric cases, children in the younger age group had a higher prevalence of solitary lesions and lower prevalence of reactions and disabilities than the older group. A total of 70.01 per cent of the affected cases were infected by intra-familial contact, 35.60 per cent were detected by contact examination, and another 22.86 per cent by active surveys. The results of the study suggest that leprosy in children is not a public health problem at the present in China, but the regular screening of children in the family of patients is still one of the important ways to detect child cases and should be recommended.

Leprosy in China: delay in the detection of cases

In a national survey in China, 27,928 cases of leprosy detected by the health authorities between 1984 and 1998 were investigated. The delay between onset of symptoms (estimated from each case's recall) and confirmed diagnosis was < or = 2 years for 55.1% of the new patients but > 10 years for 7.0%, with a median value, overall, of 22.0 months. The median delay was longer: (1) for the multibacillary cases than the paucibacillary; (2) among farmers than among factory workers; (3) among some nationalities than among others (being longest among the Tu and shortest among the Wei); and (4) for some methods of case-detection than for others. Over the study period, the mean delay decreased with time. The delay was greatest in the areas where leprosy was endemic and/or where access to health services was poor. The later the cases were detected the more likely they were to show disability. Leprosy cases are still going undetected in China, although, over the last 14 years, case-finding has significantly improved. Age, occupation, nationality, leprosy type and detection method all appear to affect the delay.

Computerization of leprosy records: national leprosy recording and reporting system in China

This paper describes the national system of leprosy recording and reporting in China and the computerization of records. The system was designed for data collection at local level and data entry by optically scanned or manual mode as well as for sophisticated data analysis. The major functions include data entry, data check, sum-up, maintenance, communication, inquiry, statistics, graph and print. A total of 17 options for epidemiological and clinical data analysis are available. Through the implementation for about 10 years, the system has gained widespread acceptance. This acceptance would facilitate introduction of computer analysis to other leprosy projects and other disease control programs in China. Up to 1998, a database of more than 740,000 records covering all the leprosy patients detected since 1949 had been established by this system.

Structure of small virus-like particles assembled from the L1 protein of human papillomavirus 16

The papillomavirus major late protein, L1, forms the pentameric assembly unit of the viral shell. Recombinant HPV16 L1 pentamers assemble in vitro into capsid-like structures, and truncation of ten N-terminal residues leads to a homogeneous preparation of 12-pentamer, icosahedral particles. X-ray crystallographic analysis of these particles at 3.5 A resolution shows that L1 closely resembles VP1 from polyomaviruses. Surface loops contain the sites of sequence variation among HPV types and the locations of dominant neutralizing epitopes. The ease with which small virus-like particles may be obtained from L1 expressed in E. coli makes them attractive candidate components of a papillomavirus vaccine. Their crystal structure also provides a starting point for future vaccine design.

Epidemiologic trends of sexually transmitted diseases in China

OBJECTIVE

To describe the current epidemiology of sexually transmitted diseases (STDs), we analyzed the time trends in distribution of reported cases of STDs in China from 1989 to 1998.

STUDY DESIGN

Based on the computerized database of the National System of STD Surveillance, a retrospective study of STD cases reported from 1989 to 1998 was carried out.

RESULTS

From 1989 to 1998, STD incidence increased significantly in men and women and demonstrated nonlinear growth trends, with the exception of gonorrhea incidence. Between 1990 and 1998, the incidence increased more in females (4.20 times) than that in males (3.79 times). Syphilis incidence increased approximately 20 times during this period at an average annual rate of 52.7%. Gonorrhea incidence increased 2.6 times during this period at an average annual rate of 11.4%, which reached a plateau from 1994 to 1997. Extramarital transmission as source of STD infection has significantly increased from 1995 to 1998.

CONCLUSION

The incidence of STDs has continued to increase in China from 1989 to 1998. The epidemic patterns are different from rates in developed counties in which behavior interventions have been successfully implemented, suggesting the need for active behavioral-intervention programs in China.

Studies on risk of leprosy relapses in China: relapses after treatment with dapsone monotherapy

Based upon the data from the Chinese National System for Leprosy Surveillance, this paper reports on the relapses in 297,343 leprosy patients [multibacillary (MB) 106,518, paucibacillary (PB) 190,825] cured by dapsone monotherapy. A total of 11,055 (MB 8675, PB 2380) patients relapsed during an accumulated follow-up period of 4,229,050 patient-years (PY), giving an overall relapse rate of 3.72 per 100 cases or 2.61 per 1000 PY, i.e., 8.14% or 5.91 per 1000 PY over an average follow-up period of 13.8 +/- 8.4 years in MB patients and 1.25% or 0.86 per 1000 PY over an average period of 14.5 +/- 8.9 years in PB patients. For either the overall relapse rate per 100 cases or per 1000 PY, the differences between MB and PB patients were statistically significant, except during 36-40 years of follow up. For both MB and PB patients, the relapse rates showed consistently significant decreases year by year, particularly in PB patients whose relapse rate per 1000 PY was 1.21 in year 10 of follow up; whereas it remained more than 10 per 1000 PY in MB patients. In view of that, the overall relapse rates in MB and PB patients cured by dapsone monotherapy were acceptably low, and most of these patients have been followed up for more than a mean incubation period of observed dapsone relapse. Along with the further extension of follow up, the risk of relapse in dapsone-cured patients will not be expected to increase. This conclusion should be considered when planning policy for the management of patients released from dapsone monotherapy.

Studies on risk of leprosy relapses in China: relapses after treatment with multidrug therapy

Based upon the data from the Chinese National System for Leprosy Surveillance, this paper reports on the relapses in 47,276 leprosy patients cured by or released from WHO-recommended multidrug therapy (WHO/MDT). The overall relapse rate was 0.73/1000 patient-years (PY). There was a statistically significant difference in the relapse rates of WHO/MDT-MB (0.61/1000 PY) and WHO/MDT-PB (1.04/1000 PY) (chi 2 = 15.7, p < 0.01) patients. For multibacillary (MB) patients, the relapse rate in patients treated with fixed-duration MDT (0.56/1000 PY) was comparable with that in patients treated with MDT until skin-smear negativity (0.73/1000 PY) (chi 2 = 2.20, p > 0.05). Our present study suggests that fixed-duration MDT is a cost-effective regimen for the treatment of leprosy in China. The present results also show that relapse of leprosy is acceptably low and has not yet become a serious clinical or public health problem but, based upon the incubation of relapse in MDT patients, it is necessary to encourage annual follow up for at least 5 years for paucibacillary (PB) and 10 years for MB patients after being released from WHO/MDT.

Prediction of elimination of leprosy in leprosy endemic areas of China

A study was carried out based upon the data from the National System for Leprosy Surveillance and using appropriate mathematical models. The results showed that of 337 counties where the national goal of basic eradication of leprosy had not been reached and in 40 counties where the WHO goal of leprosy elimination had not been achieved in 1996, the detection rates in calendar years followed exponential models with significant goodness-of-fit. In the 67 counties with downward trends of detection rates, the national goal can be met in terms of detection rate in 6% of counties before the year 2000 or 34.4% before the year 2010, or, in terms of prevalence rate in 31.3% before the year 2010. In the 11 counties with downward trends of the detection rates, the WHO target can be met in eight to ten counties within this century when the duration of disease was determined with the WHO definition. If the MB proportion among new cases increased by 10%, the target would be met one year later. However, at the same MB proportion, the change of fixed treatment schedules from PB six months and MB two years to PB nine months and MB three years will cause achievement of the goal to be postponed by two to ten years.