Platelet membrane-camouflaged silver metal-organic framework drug system against infections caused by methicillin-resistant Staphylococcus aureus

Background

Due to the intelligent survival strategy and self-preservation of methicillin-resistant Staphylococcus aureus (MRSA), many antibiotics are ineffective in treating MRSA infections. Nano-drug delivery systems have emerged as a new method to overcome this barrier. The aim of this study was to construct a novel nano-drug delivery system for the treatment of MRSA infection, and to evaluate the therapeutic effect and biotoxicity of this system. We prepared a nano silver metal-organic framework using 2-methylimidazole as ligand and silver nitrate as ion provider. Vancomycin (Vanc) was loaded with Ag-MOF, and nano-sized platelet vesicles were prepared to encapsulate Ag-MOF-Vanc, thus forming the novel platelet membrane-camouflaged nanoparticles PLT@Ag-MOF-Vanc.

Results

The synthesized Ag-MOF particles had uniform size and shape of radiating corona. The mean nanoparticle size and zeta potential of PLT@Ag-MOF-Vanc were 148 nm and − 25.6 mV, respectively. The encapsulation efficiency (EE) and loading efficiency (LE) of vancomycin were 81.0 and 64.7 %, respectively. PLT@Ag-MOF-Vanc was shown to be a pH-responsive nano-drug delivery system with good biocompatibility. Ag-MOF had a good inhibitory effect on the growth of three common clinical strains (Escherichia coli, Pseudomonas aeruginosa, and S. aureus). PLT@Ag-MOF-Vanc showed better antibacterial activity against common clinical strains in vitro than free vancomycin. PLT@Ag-MOF-Vanc killed MRSA through multiple approaches, including interfering with the metabolism of bacteria, catalyzing reactive oxygen species production, destroying the integrity of cell membrane, and inhibiting biofilm formation. Due to the encapsulation of the platelet membrane, PLT@Ag-MOF-Vanc can bind to the surface of the MRSA bacteria and the sites of MRSA infection. PLT@Ag-MOF-Vanc had a good anti-infective effect in mouse MRSA pneumonia model, which was significantly superior to free vancomycin, and has no obvious toxicity.

Conclusions

PLT@Ag-MOF-Vanc is a novel effective targeted drug delivery system, which is expected to be used safely in anti-infective therapy of MRSA.

Graphic abstract

[Efficacy and safety of ombitasvir/paritaprevir/ritonavir and dasabuvir combined with ribavirin in Asian adult patients with chronic HCV genotype 1b infection and compensated cirrhosis]

Objective: To evaluate the efficacy and safety of ombitasvir/paritaprevir/ritonavir (OBV/PTV/r) 25/150/100 mg once daily and dasabuvir (DSV) 250 mg twice daily combined with ribavirin in adult patients of Mainland China with chronic HCV genotype 1b infection and compensated cirrhosis. Methods: An open-label, multicenter, phase 3 clinical trial study was conducted in mainland China, Taiwan, and South Korea. Adult patients with compensated cirrhosis (Metavir score =F4) who were newly diagnosed and treated for hepatitis C virus genotype 1b infection with ombitasvir/paritaprevir/ritonavir and dasabuvir combined with ribavirin for 12 weeks were included. Assessed SVR rate of patients obtained at 12 and 24 weeks after drug withdrawal. Efficacy and safety were evaluated in patients who received at least one time study drugs. Results: A total of 63 patients from mainland China were enrolled, 62 of whom (98.4%) had a baseline Child-Pugh score of 5 points. The overall rate of SVR12 and SVR24 in patients was 100% (95% CI: 94.3% to 100.0%). Most of the adverse events that occurred were mild. The incidence of common (≥10%) adverse events and laboratory abnormalities included elevated total bilirubin (36.5%), weakness (19.0%), elevated unconjugated bilirubin (19.0%) and conjugated bilirubin (17.5%), and anemia (14.3%). Three cases (4.8%) of patients experienced Grade ≥ 3 adverse events that were considered by the investigators to be unrelated to the study drug. None patients had adverse events leading to premature drug withdrawal. Conclusion: Mainland Chinese patients with chronic HCV genotype 1b infection and compensated cirrhosis who were treated with OBV/PTV/r plus DSV combined with RBV for 12 weeks achieved 100 % SVR at 12 and 24 weeks after drug withdrawal. Tolerability and safety were good, and majority of adverse events were mild.

[Venous-to-arterial carbon dioxide difference to arteriovenous oxygen content difference ratio combined with lactate to predict prognosis of patients with septic shock]

OBJECTIVE

To investigate the prognostic significance of venous-to-arterial carbon dioxide difference to arteriovenous oxygen content difference ratio (Pv-aCO2/Ca-vO2 ratio) combined with lactate in patients with septic shock during the early phases of resuscitation.

METHODS

A retrospective study was conducted for 104 septic shock patients. All patients received an initial fluid resuscitation according to the Surviving Sepsis Campaign: International Guidelines for Management of Severe Sepsis and Septic Shock, 2012(SSC2012). Patients were classified into four groups according to lactate levels and Pv-aCO2/Ca-vO2 ratio at 6 h of resuscitation: group A, lactate≥2.0 mmol/L and Pv-aCO2/Ca-vO2>1.0; group B, lactate≥2.0 mmol/L and Pv-aCO2/Ca-vO2≤1.0; group C, lactate<2.0 mmol/L and Pv-aCO2/Ca-vO2>1.0; group D, lactate<2.0 mmol/L and Pv-aCO2/Ca-vO2≤1.0. The hemodynamic parameters and oxygen metabolism parameters were recorded at baseline and 6 h after fluid resuscitation. Sequential organ failure assessment (SOFA) score at day 1, day 3 were calculated. The 28-day mortality rate was recorded.

RESULTS

(1) Group A had the highest SOFA score at day 3 and group D the lowest, which were respectively 10.8±3.3, 6.7±3.6, 5.6±3.1, 4.1±2.2 in four groups. Accordingly, the 28-day mortality rate of group A was the highest and group D the lowest, which were respectively 83.3%, 59.1%, 60.0%, 14.3% in four groups. The differences were statistically significant (P<0.05). (2) The Cox regression analysis of 28 d mortality revealed that lactate levels (RR=4.306, 95%CI 1.979-9.369) and Pv-aCO2/Ca-vO2 ratio (RR=2.888, 95%CI 1.676-4.976) at T6 were independent predictors to 28-day mortality. (3) The AUCROC of Pv-aCO2/Ca-vO2 ratio combined with lactate [0.910(95%CI 0.857-0.963)] was significantly greater than the AUCROC of wither lactate [0.762(95%CI 0.673-0.852), Z=2.775; P=0.006) or Pv-aCO2/Ca-vO2 ratio [0.781(95%CI 0.693-0.868), Z=2.458; P=0.014) alone.

CONCLUSION

Combination of Pv-aCO2/Ca-vO2 ratio and lactate level at early stage of resuscitation in patients with septic shock is better than single parameter to predict the prognosis.

Association between the 8q24 rs6983267 T/G polymorphism and prostate cancer risk: a meta-analysis

Recent studies have indicated that single nucleotide polymorphisms (SNPs) within the 8q24 region may be a risk factor for prostate cancer (PCa). Here, we performed a meta-analysis to evaluate the association between the 8q24 rs6983267 T/G polymorphism and PCa risk. A systematic literature search was carried out in multiple electronic databases independently by two investigators. Pooled odds ratios (ORs) and 95% confidence intervals for 8q24 rs6983267 T/G and PCa were calculated using a fixed-effect model (the Mantel-Haenszel method). In total, 24 case-control studies from 19 articles were included in our meta-analysis. Our analysis indicated that there is a significant PCa risk associated with the rs6983267 polymorphism in a dominant model (GG vs GT+TT, pooled OR = 1.298, P < 0.001); recessive model (GG+GT vs TT, pooled OR = 1.302, P < 0.001); and homozygote comparison (GG vs TT, pooled OR = 1.494, P < 0.001). Similarly, in a subgroup analysis of European and Asian descent, our results revealed that there are associations between rs6983267 T/G polymorphism and PCa susceptibility with the dominant model (GG vs GT+TT), recessive model (GG+GT vs TT), and homozygote comparison (GG vs TT). To investigate the association between rs6983267 and risk of PCa under different clinical conditions, further analyses were conducted regarding different clinical characteristics including the Gleason score, tumor stage, and PSA level to provide a more comprehensive view of PCa risk and this SNP. Publication bias was assed using the Begg test and the Egger test, and none was detected.

Frequency and clinical outcomes of ESKAPE bacteremia in solid organ transplantation and the risk factors for mortality

BACKGROUND

Although bacteremias caused by the 6 ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) have recently been highlighted as a serious complication in solid organ transplant (SOT), more information is urgently needed. We sought to investigate the frequency and clinical outcomes of ESKAPE bacteremia in SOT and determine the risk factors for mortality.

METHODS

A retrospective analysis of bacteremia after SOT was reviewed. Risk factors for mortality caused by ESKAPE bacteremia were identified.

RESULTS

Eighty-four episodes of bacteremia were caused by ESKAPE strains. Of these strains, 41 were caused by resistant ESKAPE (rESKAPE) organisms. The only factor for bacteremia-related mortality independently associated with ESKAPE was septic shock (odds ratio [OR] = 21.017, 95% confidence interval [CI] = 5.038-87.682, P < 0.001). The factors for bacteremia-related mortality independently associated with rESKAPE bacteremia were septic shock (OR = 16.558, 95% CI = 6.620-104.668, P = 0.003) and age ≥40 years (OR = 7.521, 95% CI = 1.196-47.292, P = 0.031).

CONCLUSIONS

To improve the outcomes of transplantation, more effective therapeutic treatments are of paramount importance when older SOT recipients with bacteremia due to ESKAPE/rESKAPE organisms present with septic shock.

Correlation of tumor necrosis factor-β and interleukin-1 gene cluster polymorphism with susceptibility to bacteremia in patients undergoing kidney transplantation

BACKGROUND

Bacteremia remains a significant cause of morbidity and mortality after kidney transplantation. This study was conducted to investigate whether the polymorphisms of tumor necrosis factor (TNF)-β, interleukin (IL)-1β, and IL-1 receptor antagonist (IL-1ra) gene predicted the susceptibility to bacteremia within the first 6 months after kidney transplantation.

METHODS

Subjects comprised 82 infected kidney transplant recipients and 60 non-infected kidney transplant recipients. Bacteremia was diagnosed in 16 of the 82 infected recipients. Genomic DNA from these 142 kidney transplant recipients was extracted from peripheral blood leukocytes. Regions containing the NcoI polymorphic site at position +252 of TNF-β gene and the AvaI polymorphic site at position -511 of IL-1β gene were amplified by polymerase chain reaction (PCR) and subsequently digested with NcoI and AvaI restriction enzymes, respectively. The polymorphic regions within intron 2 of IL-1ra gene containing variable numbers of a tandem repeat (VNTR) of 86 base pairs were amplified by PCR.

RESULTS

Genotypic and allelic frequencies were similar between infected recipients and non-infected ones. Individual locus analysis showed that recipient TNF-β and IL-1ra gene polymorphisms were not associated with the presence of bacteremia (P = 0.684 and P = 0.567, respectively). However, genotype analysis revealed that recipient IL-1β-511CC genotype was strongly associated with susceptibility to develop bacteremia (P = 0.003). Recipient IL-1β-511CC genotype (odds ratio 5.242, 95% confidence intervals 1.645-16.706, P = 0.005) independently predicted the risk for bacteremia within the first 6 months after kidney transplantation.

CONCLUSIONS

These findings indicate a critical role of IL-1β gene polymorphisms in susceptibility to bacteremia after kidney transplantation, which may be useful to screen for patients at higher risk for post-transplant bacteremias. Thus, the identified individuals can benefit from preventive treatment and a less potent immunosuppressive regimen.

[Effect of CagA(+) helicobacter pylori strain on the expression of connexin 43 and cell proliferation in BGC-823 cells]

OBJECTIVE

To determine the effect of CagA(+) Helicobacter pylori(H.pylori)strain and anti-H.pylori drugs on the expression of connexin 43(Cx43) and cell proliferation of BGC-823 cells in vitro,and to investigate the relation between the changes of Cx43 expression, cell proliferation of BGC-823 cells and CagA(+)H.pylori.

METHODS

BGC-823 cells were co-cultured with CagA(+) H.pylori strain(NCTC J99) or CagA(-) H.pylori strain(NCTC 12908)at bacteria/cells ratio of 20:1,100:1 and 500:1 for 24 hours and 48 hours respectively. anti-H.pylori drugs was given in the group co-cultured at bacteria/cells ratio of 100:1 after 16 hours. In the control group, BGC-823 cells were cultured for 24 hours and 48 hours respectively,but without H.pylori or antij H.pylori drugs. Immunocytochemical SABC method and the image analysis of the computer were applied to detect the changes of Cx43 expression in BGC-823 cells. The cell proliferation was examined by methyl tetrazolium (MTT) method.

RESULTS

(1)The expression of Cx43 in the control group after cultivation for 48 hours was higher than that for 24 hours (P< 0.05). The expression of Cx43 in the groups co-cultured with CagA(+) H.pylori strain after cultivation for 48 hours was lower than that co-cultured for only 24 hours, and that of the groups co-cultured with CagA(+) H.pylori strain was lower than that of the control group for both 24 hours and 48 hours (P< 0.05). The expression of Cx43 in the groups at bacteria/cells ratio of 500:1 was lower than that at bacteria/cells ratio of 20:1 and 100:1 for both 24 and 48 hours (P< 0.05),and that at bacteria/cells ratio of 100:1 was lower than that at bacteria/cells ratio of 20:1 for 48 hours (P< 0.05).However, there was no significant difference in Cx43 expression between 24 and 48 hours in the groups co-cultured with CagA(-) H.pylori strain (P>0.05). Cx43 expression in the groups co-cultured with CagA(-) H.pylori strain at the ratio of 100:1 and 500:1 was lower than that in the control group, and Cx43 expression at the ratio of 500:1 was lower than that at the ratio of 20:1 for 24 hours and 48 hours. Cx43 expression increased after the intervention with anti-H.pylori drugs for 48 hours. (2) In the groups co-cultured with CagA(+)H.pylori strain, the optical density value of MTT indicated that the cell proliferation at the bacteria/cells ratio of 100:1 was higher than that in the control group, but no significant difference was found in other two groups co-cultured for 24 hours. After co-culturing for 48 hours, the cell proliferation at the bacteria/cells ratio of 20:1 and 100:1 was significantly accelerated, while the cell proliferation at 500:1 was inhibited. In the groups co-cultured with CagA(-) H.pylori strain,there was no change in the cell proliferation. Intervention with anti-H.pylori drugs could suppress the cell proliferation.

CONCLUSION

CagA(+) H.pylori can down-regulate the expression of Cx43 in BGC-823 cells,which is related to the reaction time and the density of H.pylori. Low density of CagA(+)H.pylori suspensions can accelerate the proliferation of BGC-823 cells, while high density can suppress the cell proliferation. The CagA(-) H.pylori has no effect on the cell proliferation. Intervention with anti-H.pylori drugs can up-regulate the expression of Cx43,and suppress the cell proliferation of BGC-823 cells.

[Cefoxitin disk diffusion test in the detection of MRS heterogenic drug-resistant strains]

OBJECTIVE

To evaluate the reliability and clinical practicability of cefoxitin disk diffusion test in the detection of methicillin-resistant staphylococcus (MRS) heterogenic drug-resistant strains.

METHODS

Three hundred and ten strains of staphylococcus isolated from clinics were detected by the oxacillin disk diffusion test, the cefoxitin disk diffusion test as well as the oxacillin agar dilution test according to the standard operation procedures of NCCLS, and the detection of mecA gene of staphylococcus was used as a criterion. The sensitivities and specitivities of the 4 methods were compared.

RESULTS

By the detection of mecA gene, the ratio for MRSA was 57.1%(113/198) and the ratio for MRCNS was 62.5%(70/112). Both the sensitivity and specificity of cefoxitin disk diffusion test in the detection of MRS were 100%, and those in the detection of MRCNS were 98.6% and 100%.

CONCLUSION

Cefoxitin disk diffusion test is reliable, simple and convenient, and it can be used as a conventional method for the detection of MRS in clinical laboratories.

Drug resistance of infectious pathogens after liver transplantation

BACKGROUND

Infection in liver recipients is related to high risk of transplantation failure and mortality. Infectious agents isolated from 55 liver recipients from January 2003 through June 2005 were studied to improve the anti-infectious therapy.

METHODS

Pathogens were isolated from routine culture. K-B method was used to examine the drug susceptibility. Extended spectrum beta-lactamase, AmpC beta-lactamase and Van gene in E.coli were examined by the agar-dilution susceptibility test and Nitrocefin test.

RESULTS

Thirty-nine of the 55 recipients got infection. The 513 strains of pathogens isolated from 1861 specimens were predominantly Gram negative bacteria and over 40% of them showed resistance to more than 4 drugs. The positive rates of extended spectrum beta-lactamse and AmpC beta-lactamse production in E.cloacae were 32.4% and 36.8%, in E.coli were 33.8% and 10.5%, but the rates of these 2 bacteria producing both lactamses were 24.3% and 7.0%. The beta-lactamse production rates of Enterococcus faecalis and Enterococcus faecium were 8.8% and 11.1%, and the resistance rates to vancomycin were 11.2% and 18.5%, respectively.

CONCLUSIONS

Infectious pathogens isolated from liver recipients are potent and multiple drug resistant. ESBLs and AmpC beta-lactamases are the major factors associated with Gram negative drug resistance. The infection of Enterococcal species presents as a particular challenge.

Low-level prenatal lead exposure and neurobehavioral development of children in the first year of life: a prospective study in Shanghai

We used a prospective study design to assess the effects of prenatal low-level lead exposure on the development of urban, inner-city children in Shanghai. Umbilical cord blood samples wee consecutively collected from 605 live newborns. Two hundred and fifty-seven samples were excluded from the study due to clotting. Lead levels were determined on 348 cord blood samples. The geometric mean was 9.2 micrograms/dl. Based on their cord blood lead levels, infants were classified into two exposure groups: 104 in a relatively low lead group (lead levels < or = 30 percentile), and 104 in a relatively high lead group (lead levels > or = 70 percentile). Seventy-five subjects failed to complete the study, and 133 babies were included in the final cohort: 69 babies in the high lead group and 64 in the low lead group. At 3, 6, and 12 months, the Bayley Scales of Infant Development were administered and capillary blood lead levels were measured. Detailed information was obtained on a wide range of variables relevant to infant development. At all three ages, the Mental Development index (MDI) scores, adjusted for confounders, were inversely related to the infants' cord blood lead levels. The difference of the mean adjusted MDI scores between low and high lead groups was 3.4 at 3 months, 6.3 at 6 months, and 5.2 at 12 months of age. These differences were statistically significant at all time points. No significant association between cord blood lead levels and the Psychomotor Development Index (PDI) scores was detected at all three visits after adjustment for confounders. Postnatal lead levels were unrelated to concurrent developmental status. We conclude that prenatal low-level lead exposure, which is relatively common in Shanghai, is associated with an adverse developmental impact on children through the first year of life.

Umbilical cord blood lead levels in Shanghai, China

This study was designed to determine the cord blood lead (BPb) levels of babies born in one urban area of Shanghai, and to preliminarily identify the demographic, social environment and prenatal factors which have an effect on the cord BPb concentrations. From August to November 1993, umbilical cord blood samples were obtained from 605 live newborns in the Yangpu Maternal and Child Hospital. 257 samples were excluded from measurement because of clotting. In 348 cord samples, the geometric mean of cord BPb levels was 9.2 micrograms/dl, with a 95% confidence interval of the mean 8.86-9.54 (micrograms/dl). 142 babies (40.8%) had cord BPb levels of 10 micrograms/dl or greater. As a result of this high percentage of newborns with BPb levels equal to or greater than 10 micrograms/dl, we estimate that each year in the Shanghai City about 60,000 newborns are at risk for developing neuropsychological deficiencies caused by maternal lead exposure during pregnancy. To investigate the factors affecting cord blood levels, the subjects with levels greater than the 70th percentile (10.7 micrograms/dl) (n = 104) and less than the 30th percentile (7.4 micrograms/dl) (n = 104) were selected to compare the demographic, environment and prenatal medical history. Increased BPb levels at birth were associated with maternal passive smoking, a family member being occupationally exposed to lead, proximity to major traffic way, household coal combustion, neighborhood coal combustion, low level of maternal occupations, and the increasing occurrence of having the high lead foodstuff pidan (preserved duck egg) during pregnancy. We conclude that prenatal lead exposure has become an important health issue for young children in Shanghai.

Probing the determinants of disulfide stability in native pancreatic trypsin inhibitor

The effects of single amino acid replacements on the stability of the 14-38 disulfide bond in the native form of bovine pancreatic trypsin inhibitor (BPTI) were measured. A total of 17 mutant proteins, with substitutions at one of 7 residues located 5-15 A from the disulfide in the native wild-type protein, were examined. The replacements were found to decrease the thermodynamic stability of the disulfide, as measured by exchange with thiol-disulfide reagents, by 0.6-5 kcal/mol, corresponding to a range of nearly 100 mV in redox potentials. The effects of the substitutions on disulfide stability were roughly correlated with the changes in side-chain volume, suggesting that optimal packing is a major factor in determining the stability of the disulfide in the wild-type protein. With only one exception, the substitutions also led to increases, as large as 50-fold, in the rates of disulfide reduction by dithiothreitol. The increased rates of reduction suggest that at least a fraction of the mutational destabilization of the disulfide is due to strain in the native protein that is relieved in the transition state for reduction. The stability of the disulfide in a peptide corresponding to the segments that are linked together by the 14-38 disulfide in native BPTI was found to be about 5 kcal/mol less than that of the disulfide in the intact wild-type protein. Together, the results with the mutant proteins and the peptide indicate that the stability of the disulfide in the native protein depends on both the local environment of the disulfide and on the ability of the rest of the protein to favor a conformation that promotes disulfide formation.

A comparative study of growth hormone (GH) and GH-releasing hormone(1-29)-NH2 for stimulation of growth in children with GH deficiency

In this study, 60 patients with proven growth hormone deficiency (GHD) of hypothalamic origin were randomized into three equal groups, and received growth hormone-releasing hormone(1-29)-NH2 (GHRH(1-29)-NH2), 30 or 60 micrograms/kg/day, or growth hormone (GH), 0.1 IU/kg/day, for 6 months. There were no significant differences in growth between the two groups given GHRH(1-29)-NH2, but growth in the GH group was significantly better than in the other two groups (p < 0.01). Mean height velocities at 6 months were 9.2, 9.3 and 14.6 cm/year for the three groups, respectively. Plasma GHRH concentrations increased steadily over the 6-month treatment period, with higher levels in the group on the higher dose. During GHRH(1-29)-NH2 treatment, serum concentrations of insulin-like growth factor I rose initially, but then fell to values similar to those before treatment. No GH antibodies were detected, but all 20 patients on high-dose GHRH(1-29)-NH2 and 19 of 20 patients on low-dose GHRH(1-29)-NH2 developed GHRH antibodies. These had almost disappeared by 9 months after stopping treatment. There was no correlation between antibody titres and increase in height. No serious side-effects were seen, but three patients receiving GHRH(1-29)-NH2 reported mild irritation at the injection site. These results from the continuous infusion of GHRH(1-29)-NH2 over 6 months suggest that this treatment, or the related use of a depot preparation, is unlikely to be as effective as GH for the promotion of growth in GHD.

Growth promoting effect of zinc supplementation in infants of high-risk pregnancies

This study was made to determine whether zinc deficiency is one of the factors involved in growth retardation of infants of high-risk pregnancies. The high risk factors were hypertension of pregnancy, diabetes mellitus, congenital heart disease, chronic nephritis, rheumatic heart disease and hyperthyroidism. 102 neonatal infants were divided into 3 groups: breast fed group, 37 cases; test group, 32 cases formula-fed with supplementary zinc 1.14-2.28 mg/kg/d; and control group, 33 cases formula-fed and supplemented with Vitamin B complex as placebo. The groups were divided by double-blind and randomized method. There were no differences in the 3 groups in sex ratio, growth status and serum zinc concentration at the beginning of the study. Anthropometric data were obtained at 0, 3 and 6 months.

The adverse effect of marginally higher lead level on intelligence development of children: a Shanghai study

We surveyed 128 preschool children in a lead-polluted area in Shanghai to study the relationship between blood lead level and neuropsychological functions, assessed by age-appropriate psychological tests. The geometric means of blood lead level was 21.7 + -10.8 micrograms/dl. Of 47 children aged below 30 months, there was no significant difference in BSID indices between the high and low lead subjects, although the high lead children tended to have poorer development scores than the low lead ones. On the other hand, of 81 children older than 46 months, the WPPSI IQ scores showed highly significant negative correlation with blood lead level. Step-wise regression and multiple analysis of covariance techniques were employed to find out and control the confounding factors. Even when 21 non-lead variables were considered, the IQ difference between high and low lead groups remained statistically significant. We concluded that the children, especially those older than 46 months, in the area investigated, did suffer from lead toxicity causing impairment in intelligence development. We support the view that marginally higher lead level in children should be taken seriously.