Biomedical subjects

Li Dai

Publications and source records attributed to Li Dai.

28 records · Page 2Linked to original sources

PubMed2003

The hemolytic activity of six arachnid cationic peptides is affected by the phosphatidylcholine-to-sphingomyelin ratio in lipid bilayers.

The hemolytic activity of six cationic amphipathic peptides (Oxki1, Oxki2, Pin1, Pin2, IsCT1 and IsCT2) from arachnids strongly depends on the source of red blood cells. The hemolytic activity of the amphipathic peptides was correlated to the phosphocholine-to-sphingomyelin ratio (PC/SM) content, the potency order of which on mammal erythrocytes ranked as follows Guinea pig>pig>sheep. The spider peptides, Oxki1 and Oxki2, prefer small unilamellar vesicles (SUV) composed of PC, but they could not disrupt SUVs made of SM only. Moreover, the membrane-disrupting activity of the scorpion peptide Pin1 was affected by increasing concentrations of SM. Only the scorpion hemolytic peptide Pin2 was able to disrupt SUVs composed merely of SM at high concentrations. Finally, the short scorpion peptides IsCT1 and IsCT2 seem to tolerate high concentrations of SM in the presence of PC for disruption of SUVs; however, the disrupting activities of IsCT1 and IsCT2 are much lower than that of the other four hemolytic peptides. The hemolytic activity caused by all six cationic peptides in mammalian erythrocytes was positively correlated to increases in temperature and increases in the concentration of benzyl alcohol, a membrane fluidizing agent. It was concluded that the hemolytic activity of the cationic peptides strongly depends on the PC/SM content of mammalian erythrocytes, in which cell membranes with a low PC/SM ratio (i.e., of low fluidity) were less disturbed than membranes with a high PC/SM ratio (i.e., of high fluidity).

Animals↗

PubMed2003

Distinct primary structures of the major peptide toxins from the venom of the spider Macrothele gigas that bind to sites 3 and 4 in the sodium channel.

Six peptide toxins (Magi 1-6) were isolated from the Hexathelidae spider Macrothele gigas. The amino acid sequences of Magi 1, 2, 5 and 6 have low similarities to the amino acid sequences of known spider toxins. The primary structure of Magi 3 is similar to the structure of the palmitoylated peptide named PlTx-II from the North American spider Plectreurys tristis (Plectreuridae). Moreover, the amino acid sequence of Magi 4, which was revealed by cloning of its cDNA, displays similarities to the Na+ channel modifier delta-atracotoxin from the Australian spider Atrax robustus (Hexathelidae). Competitive binding assays using several 125I-labelled peptide toxins clearly demonstrated the specific binding affinity of Magi 1-5 to site 3 of the insect sodium channel and also that of Magi 5 to site 4 of the rat sodium channel. Only Magi 6 did not compete with the scorpion toxin LqhalphaIT in binding to site 3 despite high toxicity on lepidoptera larvae of 3.1 nmol/g. The K(i)s of other toxins were between 50 pM for Magi 4 and 1747 nM for Magi 1. In addition, only Magi 5 binds to both site 3 in insects (K(i)=267 nM) and site 4 in rat brain synaptosomes (K(i)=1.2 nM), whereas it showed no affinities for either mammal binding site 3 or insect binding site 4. Magi 5 is the first spider toxin with binding affinity to site 4 of a mammalian sodium channel.

Amino Acid Sequence↗

PubMed2003

[Clinical features of 3798 perinatals suffering from syndromic neural tube defects].

OBJECTIVE: To investigate the patterns and associated malformations in neural tube defects (NTDs) cases. METHODS: From 1987 to 1995, hospital-based cluster sampling method was adopted for collecting data. During that period all live or still births with 28 weeks of gestation or more were assessed within 7 days after delivery. RESULTS: Three thousand seven hundred and ninety eight syndromic NTDs were identified, among which anencephaly, spina bifida and encephalocele were 997, 2394 and 407 respectively. 51.3% associated abnormalities of NTDs appeared in muscle and skeletal system, 19.6% in face, ear and neck, and 9.3% in urinary-genital system. Congenital talipes equinovarus, cleft lip with cleft palate, gastroschisis, talipes valgus, undescended testicle were frequently combined with NTDs. The most frequent association in schisis type of NTDs was NTDs accompanied by cleft lip with or without cleft palate (67.5%), followed by anencephaly with cleft palate (8.3%) and anencephaly with omphalocele (6.6%). Of all syndromic NTDs, the rate of low birth weight was 36.9%, of perinatal mortality was 71.2% and the ratio 33.1% patients were diagnosed prenatally. CONCLUSIONS: Approximately one third of NTDs may be associated with other system's malformation. Syndromic NTDs has a high perinatal mortality rate and a poor prognosis.

Abnormalities, Multiple↗

PubMed2003

[Epidemiological investigation of perinatals affected by transverse facial cleft in China].

OBJECTIVE: To study the epidemiological features of transverse cleft and its multiple congenital anomaly (MCA) patterns in China. METHODS: From 1987 through 1992, hospital-based cluster sampling method was adopted for collecting data. During that period all live or stillbirths with 28 weeks of gestation or more were assessed within 7 days after delivery. RESULTS: 94 cases of transverse facial cleft were identified among 4,489,692 births, so the prevalence rate of transverse facial cleft at birth was 0.21/10(4). The prevalence rates in urban areas and in rural areas were 0.20/10(4) and 0.23/10(4), respectively. And the rates in male and female births were both 0.21/10(4). 69 cases occurred with other malformations, among which the anomalies of ear were the most frequent association (53.6%). The perinatal fatality rate was 46.9%, a significant difference of fatality rate was found between isolated forms (16.0%) and associated forms of transverse facial cleft (58.0%). CONCLUSIONS: The prevalence rate of transverse facial cleft in China is more than the estimated rate. No significant differences are found between urban and rural areas, and between male and female births. Most of transverse facial clefts are associated forms, often as one feature of other syndromes.

China↗

PubMed2003

[Analysis of maternal mortality in China from 1996 to 2000].

OBJECTIVE: To study the trend and characteristics of maternal mortality in China from 1996 to 2000. METHODS: Population-based epidemiological survey in 116 monitoring units in China were used. RESULTS: Maternal mortality in China dropped by 17.1% from 63.9 per 100,000 live births in 1996 to 53.0 in 2000, in rural area dropped by 22.2% from 86.4 per 100,000 live births to 67.2, and in urban area only 1.0% from 29.2 per 100 000 live births to 28.9, the leading causes of maternal mortality in China are hemorrhage, preeolampsia/eclampsia and amniotic fluid embolism the maternal mortality due to hemorrhage in national level and rural level has declined by 33.8%, 34.9% respectively. CONCLUSION: The maternal mortality appears a declined trend on both the national and rural levels in China from 1996 to 2000, the maternal mortality due to hemorrhage dose also, bur the maternal mortality in urban area keeps unstable.

Cause of Death↗

PubMed2003

[The monitoring of cleft lip with or without cleft palate in China: 1996 - 2000].

OBJECTIVE: To describe the epidemiological features of cleft lip with or without cleft palate (CL +/- P) in Chinese perinatals. METHODS: From 1996 through 2000, hospital-based cluster sampling method was adopted for collecting data. During that period all live or still births with 28 weeks of gestation or more delivered in monitoring hospitals were assessed within 7 days after birth. RESULTS: The birth prevalence rates of cleft lip (CL) and of cleft lip with cleft palate (CLP) were 5.03/10,000, 8.97/10,000 respectively, then the rate of CL +/- P was 14.0/10,000. The prevalence rates in urban and rural area, in male and female births were 13.28/10,000 and 15.57/10,000, 16.06/10,000 and 11.40/10,000 respectively. Significant difference was found among maternal-age-specific prevalence rates, and the highest one was observed in >or= 35 maternal age group. 87.25% of CL +/- P was isolated forms. No secular trend was found during that period. The perinatal fatality rate of CL +/- P was 19.04%, and the rate in isolated forms was 12.69%, but the rate in syndromic CL +/- P was as high as 62.60%. CONCLUSIONS: No decline trend in prevalence rate of CL +/- P was observed during 1996 approximately 2000. Compared with prevalence rates of CL +/- P in some foreign countries, it was higher in China during same period.

Adult↗

PubMed2002

Purification, structure-function analysis, and molecular characterization of novel linear peptides from scorpion Opisthacanthus madagascariensis.

In the previous report [Biochem. Biophys. Res. Commun. 286 (2001) 820], we described a novel short linear peptide, IsCT, with cytolytic activity isolated from the venom of scorpion Opisthacanthus madagascariensis. From the same scorpion venom, we further purified and characterized three short linear peptides named IsCT2, IsCTf, and IsCT2f that shared high homology with IsCT, while with different C-terminal areas between IsCT/IsCT2 and IsCTf/IsCT2f. Structure-activity relationship was analyzed by performing vivo and vitro assays and circular dichroism spectroscopy. Like IsCT, IsCT2 showed broad activity spectra against microbes (Gram positive and negative bacteria as well as fungi) and relatively weak hemolytic activity against sheep red blood cells. It adopts an amphipathic alpha-helical structure in aqueous TFE and is able to disrupt the artificial membrane. However, the other two peptides IsCTf and IsCT2f showed no activity in antimicrobial or hemolytic assay. Furthermore, IsCTf and IsCT2f cannot form amphipathic alpha-helix while demonstrating random coil structure in aqueous TFE, which might result in their lost cytolytic activity. IsCTf and IsCT2f both exist in the crude venom and are proved to be enzymatic products from IsCT and IsCT2. Whether they have some other biological activity is still unclear. In addition, we got the cDNAs encoding the precursors of IsCT and IsCT2. Besides the signal peptide, they still contain an unusual acidic pro-peptide at the C-terminal that was quite different from other known precursors of scorpion venom peptides. The novel structure and biological activity of these peptides proposed them to be a new class in scorpion venom.

Amino Acid Sequence↗

PubMed2002

A draft sequence of the rice genome (Oryza sativa L. ssp. indica).

We have produced a draft sequence of the rice genome for the most widely cultivated subspecies in China, Oryza sativa L. ssp. indica, by whole-genome shotgun sequencing. The genome was 466 megabases in size, with an estimated 46,022 to 55,615 genes. Functional coverage in the assembled sequences was 92.0%. About 42.2% of the genome was in exact 20-nucleotide oligomer repeats, and most of the transposons were in the intergenic regions between genes. Although 80.6% of predicted Arabidopsis thaliana genes had a homolog in rice, only 49.4% of predicted rice genes had a homolog in A. thaliana. The large proportion of rice genes with no recognizable homologs is due to a gradient in the GC content of rice coding sequences.

Arabidopsis↗

PubMed2002

[An epidemiological investigation of perinatal teratomas in China].

OBJECTIVE: To investigate the prevalence rate and epidemiological features of teratomas in China. METHODS: From 1987 through 1992, hospital-based cluster sampling method was adopted for collecting data. During that period all live or still births with 28 weeks of gestation or more were assessed within 7 days after delivery. RESULTS: 238 teratoma cases were identified in 4,489,692 births, including 198 isolated and 40 associated forms of teratomas. The prevalence rates of total teratomas, isolated and associated forms of teratomas were 0. 53/10000, 0.44/10000, 0.09/10000 respectively. The prevalence rates in urban areas and rural areas were 0.46/10000 and 0.66/10000, respectively. The prevalence rates of teratomas in male and female births were 0.80/10000 and 0.27/10000 correspondingly. The ratio of male to female teratomas was 1:2.76. The perinatal fatality rate of teratomas was 55.0%. CONCLUSION: The most frequent teratomas were isolated forms. Time trends have not been found in the occurrence of teratomas. High prevalence in urban areas has been observed, compared to that in rural areas. The prevalence of teratomas in female births is three times as high as that in male births. In view of the high fatality rate, prenatal diagnosis and perinatal management of teratomas should be strengthened.

China↗

PubMed2002

[Dynamic monitoring of neural tube defects in China during 1996 to 2000].

OBJECTIVE: The database from Chinese Birth Defects Monitoring Network was used to describe the epidemiological features and secular trends of neural tube defects (NTDs) prevalence during Jan. 1996 to Dec. 2000, including anencephaly, spina bifida and encephalocele. METHODS: Data were collected with hospital-based cluster sampling method. During the period, all live or still births with 28 weeks or more of gestation were assessed within seven days after delivery. RESULTS: There were 2 873 case with NTDs identified from 2 281 616 births, with an overall prevalence rate of 12.95 per 10,000 births. And, the prevalence rates of anencephaly, spina bifida and encephalocele were 5.02 per 10,000, 6.30 per 10,000 and 1.64 per 10,000, respectively. Significant falls in overall prevalence rates of NTDs and of anencephaly were observed. The prevalence rates of NTDs were 9.75 per 10,000 and 15.96 per 10,000 in male and female births, respectively, 7.76 per 10,000 and 25.20 per 10,000 in the urban and rural areas, respectively, and 19.90 per 10,000 and 5.81 per 10,000 in north and south China, respectively. The prevalence was higher in the groups with maternal age of less than 20 years and more than 30 years than in those other maternal ages. Preterm babies and babies with low birth weight accounted for 50.9% and 50.6% of perinatal babies with NTDs, respectively, with a perinatal mortality of 77.8%. CONCLUSIONS: In China, the occurrence of NTDs was higher in female births than in male births, higher in the rural than in the urban, and higher in the north than in the south. Annual prevalence rate of NTDs in China presented a declining trend, but still higher than that in the other countries at the same time period. Babies with NTDs were in poor birth quality, higher perinatal mortality and poor prognosis. Effective preventive measures and prenatal diagnosis should be strengthened to reduce the occurrences of neural tube defects.

Adult↗