[Triptolide reverses apatinib resistance in gastric cancer cell line MKN45 via inhibition of heat shock protein 70].

Objective: To investigate the effect of triptolide, a specific inhibitor of heat shock protein 70 (HSP70), on apatinib resistance in gastric cancer cells line MKN45. Methods: The apatinib-resistant cells (MKN45/AR) and MKN45 parental cells were treated with apatinib, triptolide and apatinib combined with triptolide, respectively. CCK-8 assay was performed to determine the half maximal inhibitory concentration (IC(50)) of MKN45/AR and MKN45 cells in the presence of different treatment. The mRNA expression of heat shock protein gene (HSPA1A and HSPA1B) was detected by RT-PCR, while the protein expression of heat shock protein 70 was analyzed using Western blot in MKN45/AR and MKN45 cells. Results: The IC(50) values of apatinib-sensitive and apatinib-resistant MKN45 cells were 10.411 µmol/L and 70.527 µmol/L, respectively, showing a significant difference (P<0.05). The mRNA expression of HSPA1A and HSPA1B in MKN45/AR cells was significantly higher than that in MKN45 cells (P<0.001). The protein expression of heat shock protein 70 was significantly decreased after 0.25 µmol/L triptolide treatment in MKN45/AR cells (P<0.01). When heat shock protein 70 was inhibited by triptolide, the IC(50) value of apatinib in MKN45/AR cells was reduced to 11.679 µmol/L, which was significantly lower than cells treated with apatinib alone (P<0.05). Conclusions: The apatinib-resistant MKN45 cells have high levels of heat shock protein 70. Low doses of triptolide can significantly inhibit heat shock protein 70, leading to reverse the resistance phenotype of MKN45/AR cells. Therefore, inhibition of heat shock protein 70 provides a new therapy strategy for patients with apatinib resistance.

Epidemiology and risk factors for faecal extended-spectrum ß-lactamase-producing Enterobacteriaceae (ESBL-E) carriage derived from residents of seven nursing homes in western Shanghai, China.

Nursing homes (NHs) have been implicated as significant reservoirs of antibiotic-resistant organisms causing severe infectious disease. We investigated the prevalence and molecular epidemiology of, and risk factors for, faecal carriage of extended-spectrum ß-lactamase-producing Enterobacteriaceae (ESBL-E). A multicentre cross-sectional study was conducted in seven NHs in Shanghai between March 2014 and May 2014. Antimicrobial susceptibility testing and polymerase chain reaction were used to detect genes coding for ESBLs and carbapenemases. NH records at individual-resident level and facility level were examined for potential risk factors. Four hundred and fifty-seven Enterobacteriaceae isolates were collected of which 183 (46·92%) were colonized by ESBL-E. CTX-M enzymes (198/200, 99%) predominated, with CTX-M-14 (84/200, 42%) the most common types. Two carbapenemase producers harboured blaKPC-2. Resistance rates to carbapenems, TZP, AK, FOS, CL and TGC were low. History of invasive procedures [odds ratio (OR) 2·384, 95% confidence interval (CI) 1·318-4·310, P = 0·004], narrow-spectrum cephalosporins (OR 1·635, 95% CI 1·045-2·558, P = 0·031) and broad-spectrum cephalosporins (OR 3·276, 95% CI 1·278-8·398, P = 0·014) were independently associated with ESBL-E carriage. In conclusion, NH residents have a very high prevalence of faecal carriage of ESBL-E. Continuous and active surveillance is important, as are prudent infection control measures and antibiotic use to prevent and control the spread of these antibiotic-resistant strains.

Anomalous optical forces on the anisotropic Rayleigh particles.

We investigate the optical forces on the radially anisotropic spheres from an incident plane wave based on our generalized full-wave scattering theory and the Maxwell stress tensor integration techniques. We demonstrate that the optical force on the Rayleigh sphere with radial anisotropy does not always obey the well-known Rayleigh's law F~k04a(6) (where k(0) is the wave number and a is the radius of the sphere), but could be anomalous with the laws such as F~k00a(2), F~k0-2a(0), and F~k08a(10) under certain conditions. Therefore, the optical force on the anisotropic Rayleigh spheres is enhanced at the electric dipole resonance, and may be further increased by tuning the anisotropic parameters. On the contrary, the optical forces on the anisotropic spheres can be largely reduced for anisotropic spheres with electromagnetic transparency.

First Report of Nigrospora Leaf Blight on Sesame Caused by Nigrospora sphaerica in China.

Sesame (Sesamum indicum L.) is an important oilseed crop widely grown in the central regions of China. A new leaf blight has increasingly been observed in sesame fields in Anhui, Hubei, and Henan provinces since 2010. Approximately 30 to 40% of the plants were symptomatic in the affected fields. Initial symptoms were yellow to brown, irregularly shaped lesions. Lesions later expanded and the affected leaves tuned grayish to dark brown and wilted, with a layer of whitish mycelial growth on the underside. Severe blighting caused the center of lesions to fall out, leaving holes in the leaves. Sections of symptomatic leaf tissues were surface-sterilized in 75% ethanol for 30 s, then in 1% HgCl2 for 30 s, rinsed three times in sterile distilled water, and plated onto potato dextrose agar (PDA). The resulting fungal colonies were initially white, and then became grayish-brown with sporulation. Conidia were single-celled, black, smooth, spherical, 14.2 to 19.8 µm (average 17.1 µm) in diameter, and borne on a hyaline vesicle at the tip of each conidiophore. Morphological characteristics of the isolates were similar to those of Nigrospora sphaerica (1). To verify the identification based on morphological features, the ITS1-5.8S-ITS2 region of the ribosomal RNA was amplified using ITS1 (5'-TCCGTAGGTGAACCTGCGG-3') and ITS4 (5'-TCCTCCGCTTATTGATATGC-3') primers (3), and then sequenced and compared to the GenBank database through a BLAST search. Comparison of the sequence revealed 100% similarity to N. sphaerica (GenBank Accession No. JF817271.1). On the basis of morphological data and the ITS rDNA sequence, the isolate was determined to be N. sphaerica. Pathogenicity tests were conducted using fresh and healthy sesame leaves of 10 plants. A conidial suspension (106 conidia/ml) collected from a 7-day-old culture on PDA was used for inoculation. Leaves of 10 plants were spray-inoculated with the spore suspension at the 6-week-old growth stage, and an additional 10 plants were sprayed with sterile water. Inoculated plants were covered with polyethylene bags to maintain high humidity. Plants were kept at 28°C and observed for symptom every day. Ten to 15 days after inoculation, inoculated leaves developed blight symptoms similar to those observed on naturally infected leaves. No symptoms were observed on the control leaves. N. sphaerica was re-isolated from the inoculated leaves, thus fulfilling Koch's postulates. N. sphaerica has been reported as a leaf pathogen on several hosts worldwide (2). To our knowledge, this is the first report of Nigrospora leaf blight on sesame caused by N. sphaerica in China. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CMI, Kew, Surrey, UK, 1971. (2) D. F. Farr and A. Y. Rossman. Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ . July 01, 2013. (3) M. A. Innis et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

Controlling light scattering and polarization by spherical particles with radial anisotropy.

Based on full-wave electromagnetic theory, we derive the zero-forward and zero-backward scattering conditions for radially anisotropic spheres within the quasi-static limit. We find that the near-field intensity can be tuned dramatically through the adjustment of the radial anisotropy, while the far-field light scattering diagrams are similar under the zero-forward or zero-backward scattering conditions. Generalized "Brewster's angle" for anisotropic spheres is also derived, at which the scattering light is totally polarized. In addition, the high-quality polarized scattering wave and the tunable polarization conversion can be achieved for the radially anisotropic spheres.

Non-Rayleigh scattering behavior for anisotropic Rayleigh particles.

Derived from the light scattering by a radially anisotropic sphere, unusual scattering behavior is exhibited, which breaks the Rayleigh law (scattering efficiency Q(sca)~q(4) as q→0, where q is the size parameter). Under certain conditions, we demonstrate an asymptotical relation between Q(sca) and q, i.e., Q(sca)=Fq(8), which is not realizable for isotropic particles in Rayleigh regime. Moreover, suitable adjustment of the anisotropic parameters can further suppress the coefficient F, resulting in enhanced transparency of the anisotropic particle.

[Changing trends of HIV testing and HIV self-testing in men who have sex with men on a gay social networking app].

Objective: To understand the changing trends of HIV testing rates, with a focus on HIV self-testing, and to evaluate the impact of HIV self-testing on expanding HIV testing among MSM in China in past few years. Methods: MSM were recruited online nationwide via a gay social networking app (Blued) from 2013 to 2016 and 2018. The survey collected information about socio-demographic backgrounds, sexual behaviors, and prior HIV testing experiences, including HIV self-testing. Trend analyses were conducted. Results: Respectively, 1 342, 1 424, 1 173, 2 105 and 699 MSM were recruited nationwide from 2013 to 2016, and in 2018. The mean age was (30.6±6.6)years in 2013 and showed a decreasing trend afterwards. The HIV testing rate was 60.0% (805/1 342) in 2013 and there was a rising trend from 2013 to 2016, and 2018 (trend Z =19.3, P <0.001), reaching a peak at 77.3% (540/699) in 2018. Further, the HIV self-testing rate increased from 19.3% (259/1 342) in 2013 to 58.1% (406/699) in 2018 (χ2=237.5, P <0.001). The proportion of MSM who had HIV self-testing among prior HIV testers significantly increased from 32.2% (259/805) to 75.2% (406/540) during the study period (trend Z =14.3, P <0.001). Conclusions: The HIV testing rate, HIV self-testing rate and proportion of men who had HIV self-testing among former HIV testers among web-based Chinese MSM showed substantial increases from 2013 to 2016,and 2018. This suggests that HIV self-testing may have a significant effect on the expansion of HIV testing coverage in MSM, and has important public health implications for HIV/AIDS prevention in China.

[The roles of two HIV self-testing models in promoting HIV-testing among men who have sex with men].

Objective: To evaluate the roles between two different HIV self-testing models in promoting HIV-testing among men who have sex with men (MSM). Methods: This paper focuses on two HIV self-testing service models. The first; is the online self-testing model (HIV self-testing conventional model) with the sexual health promotion network platform. The other one is an innovative HIV self-testing model (secondary distribution model), based on the previous program. The two different self-testing models, including the number of indexes and alters, the positive rate, and the demographics of indexes and alters, are compared. The influence of volunteers with or without leadership on the number of HIV self-test kits distributed or self-use is analyzed through the leadership survey scale. Results: The return rates of HIV self-testing results in the two models are 94.7%(323/341) and 99.2%(1 141/1 150), respectively, within 30 days. The proportion of alters in the secondary distribution is significantly higher (45.9%,281/612) than the conventional HIV self-testing (6.3%,20/318). In the secondary distribution model, the difference between the number of indexes and alters indicators including age, marital status, residence, sex orientation, anal sex with men in the past six months, and HIV test are statistically significant (χ2 test, all P<0.05). The opinion leader of MSM has significantly impacted the promotion of HIV self-testing (P<0.05). Conclusions: Both models can promote HIV self-testing, result return, and HIV positive detection among MSM. In terms of expanding the testing and detection of HIV positive, the secondary distribution mode shows more obvious advantages, which significantly promotes a large number of MSM who have never been tested for HIV to undergo HIV testing. Influential indexes have a significant effect on increasing the HIV testing rate and promoting HIV testing among MSM.

Resistance trends among clinical isolates in China reported from CHINET surveillance of bacterial resistance, 2005-2014.

With the aim of gathering temporal trends on bacterial epidemiology and resistance from multiple laboratories in China, the CHINET surveillance system was organized in 2005. Antimicrobial susceptibility testing was carried out according to a unified protocol using the Kirby-Bauer method or automated systems. Results were analyzed according to Clinical and Laboratory Standards Institute (CLSI) 2014 definitions. Between 2005 and 2014, the number of bacterial isolates ranged between 22,774 and 84,572 annually. Rates of extended-spectrum ß-lactamase production among Escherichia coli isolates were stable, between 51.7 and 55.8%. Resistance of E. coli and Klebsiella pneumoniae to amikacin, ciprofloxacin, piperacillin/tazobactam and cefoperazone/sulbactam decreased with time. Carbapenem resistance among K. pneumoniae isolates increased from 2.4 to 13.4%. Resistance of Pseudomonas aeruginosa strains against all of antimicrobial agents tested including imipenem and meropenem decreased with time. On the contrary, resistance of Acinetobacter baumannii strains to carbapenems increased from 31 to 66.7%. A marked decrease of methicillin resistance from 69% in 2005 to 44.6% in 2014 was observed for Staphylococcus aureus. Carbapenem resistance rates in K. pneumoniae and A. baumannii in China are high. Our results indicate the importance of bacterial surveillance studies.

Detection of aminoglycoside resistance related genes in multidrug-resistant Acinetobacter baumannii isolated from a single institute of Shanghai, China.

AIM: Aminoglycoside resistance is common in Acinetobacter baumannii. We investigated aminoglycoside resistance genes in clinical multidrug-resistant Acinetobacter baumannii strains isolated from the Chinese population. METHODS: One-hundred-and-seven strains of multidrug-resistant Acinetobacter baumannii were isolated from Ruijin Hospital in Shanghai, China. The minimum inhibitory concentrations (MICs) of amikacin, kanamycin, tobramycin, gentamicin, netilmicin and neomycin for these strains were determined with agar dilution method. 16S rRNA methylase genes and eight aminoglycoside modifying enzyme genes were tested via polymerase chain reaction. RESULTS: We found MICs of amikacin, kanamycin, tobramycin, gentamicin, netilmicin and neomycin in these strains with doses of ≥64 µg/mL, ≥64 µg/mL, ≥128 µg/mL, ≥128 µg/mL, ≥32 µg/mL and ≥8 µg/mL, respectively. Most of those strains showed a high-level resistance to aminoglycosides. ArmA was found in 90% (97/107) of the strains. Six modifying enzyme genes, including aac(6')-Ib, aac(6')-II, aac(3)-II, aac(3)-I, aph(3')-I and ant(3")-I were found with a positive rate of 47%, 50%, 28%, 31%, 93% and 96%, respectively. CONCLUSION: Multidrug-resistant Acinetobacter baumannii is highly resistant to aminoglycosides. Resistant genes could coexist in one strain, therefore, strict implementation of infection control measures is essential to avoid the rapid spread or outbreaks of these multidrug-resistant Acinetobacter baumannii in healthcare-associated facilities.

Production of monoclonal antibody against a hemolysin (Vp-TRH) produced by Vibrio parahaemolyticus.

The antigenicity of a hemolysin (Vp-TRH: Vp-TDH related hemolysin) produced by Kanagawa phenomenon-negative clinical isolates of Vibrio parahaemolyticus was studied using monoclonal antibodies (MAbs). A total of 12 hybridoma clones which produced MAbs against Vp-TRH were established. All MAbs contained the Kappa light chain and were IgG type. These MAbs were divided into a minimum of 5 different specificity groups, including antibodies specific to Vp-TRH and common to both Vp-TRH and Vp-TDH, a possible pathogenic toxin of Kanagawa phenomenon-positive V. parahaemolyticus. These results clearly show the immunological similarity and dissimilarity (specificity) of Vp-TRH and Vp-TDH.

A mutant hemolysin with lower biological activity produced by a mutant Vibrio parahaemolyticus.

A mutant toxin (m-TDH) of thermostable direct hemolysin (Vp-TDH) of Vibrio parahaemolyticus was isolated from the culture of a strain of this organism mutagenized with N-methyl-N'-nitro-N-nitrosoguanidine. Although the m-TDH had a molecular structure similar to the native Vp-TDH, the m-TDH retained only about 7% residual hemolytic activity of the native toxin. Furthermore, other biological activities of m-TDH, such as lethality in mice and enterotoxicity in rabbit ileal loops, were also weakened. The m-TDH was immunologically indistinguishable from the native Vp-TDH. These results suggest that the m-TDH is only slightly different in structure from the native Vp-TDH. Also, the mutagenized site in m-TDH, which is not immunogenic, seems to be involved in expressing not only hemolytic activity but also lethal and enterotoxic activity.

[Development and application of enzyme-linked immunosorbent assay using monoclonal antibody against a hemolysin (Vp-TRH) of Vibrio paraheamolyticus--evidence that Vp-TRH producing-Kanagawa phenomenon-negative V. parahaemolyticus is a human pathogen].

Although it has been well established that Kanagawa phenomenon-positive Vibrio parahaemolyticus is a human enteropathogen, the Kanagawa phenomenon-negative one has been considered to be probably not pathogenic. We have found, however, an outbreak of gastroenteritis due to Kanagawa phenomenon-negative V. parahaemolyticus which produces a new toxin (Vp-TRH) resembling to Vp-TDH, a responsible toxin of Kanagawa phenomenon. In this study, we developed monoclonal antibodies against Vp-TRH which were used for development of an enzyme-linked immunosorbent assay (ELISA) for specifically detecting Vp-TRH. The ELISA was applied for analysis of production of Vp-TRH by various isolates of V. parahaemolyticus and we found that Vp-TRH-producing strains were derived mostly from human diarrheal stool, and not from the environment or sea foods. The results of the rabbit ileal loop test showed that Vp-TRH-producing (Kanagawa phenomenon-negative) strains, as well as Vp-TDH-producing (Kanagawa phenomenon-positive) strains could induce fluid accumulation. These results indicate the possibility that Vp-TRH-producing Kanagawa phenomenon-negative V. parahaemolyticus is a human enteropathogen.

[Clinical study on jiang tang san in treating non-insulin dependent diabetes mellitus patients].

The therapeutic effect of Jiang Tang San (JTS) in 30 cases with non-insulin dependent diabetes mellitus (NIDDM), was observed, whose fasting blood glucose ranged from 11.1 mmol/L to 13.8 mmol/L. The results suggested that JTS has significant effects on NIDDM patients in the lowering of blood glucose, blood lipid and blood pressure levels. The clinical symptoms and blood glucose improved rapidly. JTS promoted the elevation of serum insulin level 1 hour after meal. The total effective rate of lowering blood glucose reached 86.7%. The results showed JTS is better than medication of berberine on lowering blood glucose (P < 0.01) and JTS was still effective when patients failed to respond to other hypoglycemics or on recurrence. There were no significant side-effects during the course of treatment.

Intranasal immunisation with Stx2B-Tir-Stx1B-Zot protein leads to decreased shedding in goats after challenge with Escherichia coli O157:H7.

Ruminants are an important reservoir of Escherichia coli O157:H7. To reduce E coli O157:H7 excretion by these animals could play a key role in prevention and control of human infections. In the present study, the authors used 12 three-month-old goats to evaluate the efficacy of intranasal administration of the Stx2B-Tir-Stx1B-Zot protein. These goats were inoculated on days 0 and 21 and infected with 10(10) colony-forming units (cfu) of E coli O157:H7 by oral inoculation on day 36. Faecal shedding was monitored daily for two weeks. All of six goats immunised with recombinant protein elicited significant Stx2b-Tir-Stx1b-Zot-specific serum IgG antibodies, and three of them also showed production of antigen-specific IgA in faeces. The immunised goats showed much less shedding of E coli O157:H7 after challenge. These results demonstrate the potential for the use of Stx2B-Tir-Stx1B-Zot protein in mucosal vaccine formulations to prevent colonisation and shedding of E coli O157:H7 in goats.

A novel sequence-based coa genotyping method to discriminate nosocomial methicillin-resistant Staphylococcus aureus isolates.

AIM: To evaluate a novel sequence-based coa typing method in classification for nosocomial methicillin-resistant Staphylococcus aureus. METHOD: D1 and D2 regions of coa gene were used to discriminate methicillin-resistant Staphylococcus aureus and compared with other classical sequence-based methods with discriminate power. RESULTS: All MRSA isolates were divided into 11 types and about 20 subtypes with coa typing method here. The discriminate power of this coa typing method was better than MLST or spa method. CONCLUSION: It was demonstrated that this coa method is a simple, rapid, and effective technique applicable for outbreak or local nosocomial MRSA investigations in the future.

Return migration of Helicoverpa armigera (Lepidoptera: Noctuidae) during autumn in northern China.

The autumn migration of Helicoverpa armigera (Hübner) was observed with radar and two types of light-trap at Langfang, Hebei province, China in 2001 and 2002. The sudden increase in the proportion of H. armigera moths in the searchlight trap indicated migration into the area and catches increased 10-fold during the second half of the night due to the landing of migrants before dawn. The moths' migratory flights took place at up to 2000 m above the ground, and moths flew differentially at times, and heights, when favourable (i.e. northerly) winds occurred. This facilitated the maximum displacement of moths towards the south during these 'return' migrations. The moths flew over the radar site at consistently high densities through the night, and the resulting flight durations of c. 10 h, at displacement speeds of 30-33 km h-1, would allow moths emerging in the far northeast of China (i.e. Liaoning and Jilin provinces and the Inner Mongolia autonomous region) to migrate into northern China (Hebei, Shandong and Henan provinces). The association of the seasonal migratory movements of H. armigera with crops in northern China is briefly discussed.

[Observation of immune responses to human sperm antigens in vasectomized men and men sterilized with intravasally injected drug].

PIP: 135 sterilized men whose vas deferens were injected with a drug 4 months-10 years previously, and another 35 men vasectomized 10-20 years previously were examined for detectable immune responses to human sperm antigens in the peripheral blood by using the Kibrick test, the Franklin-Dukes test, the Isojima test, and the leucocyte adherence inhibition test (LAI test); 29 normal fertile men were used as controls. Results were as follows. In the normal fertile men, positivity was zero by the 3 humoral immunological tests, but 10.7% by the LAI test. During various periods after intravasal injection of the drug, a considerable proportion of sterilized men showed positive reactions in different degrees to the 4 tests; in comparison with the normal fertile group, there were statistically significant differences. The peak incidences of sperm agglutinating and immobilizing antibodies occurred during the period from 6 months-2 years after injection. Although the positive incidence by the LAI test was also highest in this period, it was not significantly different from that of other periods. The immobilizing antibody generally occurred together with the agglutinin, and the incidences of sperm antibodies were correlated with the positive incidence by the LAI test. In the postvasectomy group, there also existed humoral and cellular immune responses to sperm antigens, but the incidence of antibodies, especially immobilizing antibodies (2.9%) were lower than those of the postinjection group. There was no significant decline in positive incidence by the LAI test. (author's modified)^ieng

Purification and characterization of a hemolysin produced by a clinical isolate of Kanagawa phenomenon-negative Vibrio parahaemolyticus and related to the thermostable direct hemolysin.

A clinical isolate (strain 4037) of Kanagawa phenomenon-negative Vibrio parahaemolyticus was studied. Although the strain was judged to be Kanagawa phenomenon-negative by various conventional tests, it produced a new hemolysin (named Vp-TRH, for thermostable direct hemolysin [Vp-TDH]-related hemolysin) that was related to the Vp-TDH produced by ordinary Kanagawa phenomenon-positive V. parahaemolyticus. Vp-TRH was purified by ammonium sulfate fractionation and successive column chromatographies on DEAE-cellulose, hydroxyapatite, and Mono Q. The molecular weight of Vp-TRH was estimated as 48,000 by Sephadex G-100 gel filtration, and the molecular weight of the subunit was estimated to be 23,000 by sodium dodecyl sulfate-slab gel electrophoresis. Thus, like Vp-TDH, Vp-TRH seems to be composed of two subunits. The isoelectric point of Vp-TRH was determined to be 4.6. Vp-TRH showed lytic activities different from those of Vp-TDH on erythrocytes from various animals, especially those from calves, chickens, and sheep. The hemolytic activity of Vp-TRH was labile on heat treatment at 60 degrees C for 10 min, unlike that of Vp-TDH. The immunological similarities, but not the identities of Vp-TRH and Vp-TDH, were demonstrated by Ouchterlony, neutralization, and latex agglutination tests. Thus, we conclude that this clinical isolate of Kanagawa phenomenon-negative V. parahaemolyticus produces a new type of hemolysin that is similar, but not identical, to Vp-TDH, which is usually produced by Kanagawa phenomenon-positive V. parahaemolyticus.

Rapid analysis of CGG repeat length in the FMR1 gene.

The number of trinucleotide CGG repeats at the 5' untranslated region of the FMR1 gene is associated with the fragile X syndrome of mental retardation. We screened for the CGG repeat length in the FMR1 gene of the X-chromosomes from unrelated normal Chinese subjects recruited in Hong Kong and Dalian, a southern and a northern Chinese city respectively. These cities are about 3000 km apart and the residents have few historical interactions. Genomic DNA was analysed by PCR and detected by Southern hybridisation with a radiolabelled (CGG)5 probe for the CGG repeat number. A different distribution pattern of CGG allele size from the Caucasians is observed. It is a bimodal pattern with the most common CGG repeats allele at 29 against 30 in the Caucasians. Among the Hong Kong subjects, five alleles of more than 50 CGG repeats were detected, and four of those were in heterozygous females. There was no difference in the repeat patterns in subjects from the two cities, suggesting no genotypic variation in FMR1 between northern and southern Chinese.