[Identification of vertical transmission of hepatitis B virus from mother to children by direct sequencing a segment of surface gene of hepatitis B virus]

SUBJECTIVE

To explore the reason for the failure to interrupt vertical transmission of hepatitis B virus (HBV) from mother to children in Chinese subjects by vaccination.

METHODS

HBV nucleotide sequences isolated from three sets of mother/children pairs were analyzed. HBV DNA from the surface antigen region encoding the amino acids 101 to 160 of hepatitis B surface antigen (HBsAg) was amplified and sequenced from HBsAg positive mother and their children.

RESULTS

Nucleotide and deduced amino acid sequences were absolutely identical in the mother and children in family one and two respectively. However, there were five nucleotides different in family one's isolates compared with the family two's isolates. All of them were a subtype. In one child of family three, with coexisted HBsAg and anti-HBs, sequencing result revealed a point mutation which predicted a change from glycine to arginine at residue 145 in the second loop of the determinant. The mother and another child had a glycine at this position.

CONCLUSION

This study revealed the vertical transmission linkage of HBV between the mother and children in a molecular level, and also first described a codon 145 immune escape mutant in Chinese vaccinated children.

The specificity of the transforming growth factor beta receptor kinases determined by a spatially addressable peptide library

Type I and II receptors for the transforming growth factor beta (TGF-beta) are transmembrane serine/threonine kinases that are essential for TGF-beta signaling. However, little is known about their in vivo substrates or signal transduction pathways. To determine the substrate specificity of these kinases, we developed combinatorial peptide libraries synthesized on a hydrophilic matrix that is easily accessible to proteins in aqueous solutions. When we subjected these libraries to phosphorylation by the cAMP-dependent protein kinase, we obtained the optimal peptide sequence RRXS (I/L/V), in perfect agreement with the substrate sequence deduced from mutagenesis and crystal structure analyses. By using the same libraries, we showed that the optimal substrate peptide for both the type I and II TGF-beta receptors was KKKKKK(S/T)XXX. Since the two kinases are thought to play different roles in intracellular signal transduction, it was a surprise to find that they have almost identical substrate specificity. Our method is direct, sensitive, and simple and provides information about the kinase specificity for all the amino acid residues at each position.

[Genetic variation in the cleavage site of the precore region of hepatitis B virus in Chinese patients with fulminant hepatitis]

In this study, a previously not documented variant of hepatitis B virus was described in Chinese patients with fulminant hepatitis. The entire precore/core region amplified from samples was cloned into a bacterial vector and sequenced by dideoxy chain termination reaction. Double amino acid substitutions were seen in the precore region in the isolates: one from glycine to aspartic acid at codon 29 previously reported; the other substitution of phenylalanine for valine at codon 17 in the cleavage site of hepatitis B virus. Loss of hepatitis B virus e antigen in these patients with fulminant hepatitis might therefore be due to the mutation in the cleavage site, rather than the emergence of a stop codon in the precore region of hepatitis B virus. Accumulation of hepatitis B e antigen precursor within the hepatocytes might account for the fulminant hepatitis exacerbation.

Development of Bacillus thuringiensis CryIC Resistance by Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae)

Selection of resistance in Spodoptera exigua (Hubner) to an HD-1 spore-crystal mixture, CryIC (HD-133) inclusion bodies, and trypsinized toxin from Bacillus thuringiensis subsp. aizawai and B. thuringiensis subsp. entomocidus was attempted by using laboratory bioassays. No resistance to the HD-1 spore-crystal mixture could be achieved after 20 generations of selection. Significant levels of resistance (11-fold) to CryIC inclusion bodies expressed in Escherichia coli were observed after seven generations. Subsequent selection of the CryIC-resistant population with trypsinized CryIC toxin resulted, after 21 generations of CryIC selection, in a population of S. exigua that exhibited only 8% mortality at the highest toxin concentration tested (320 (mu)g/g), whereas the 50% lethal concentration was 4.30 (mu)g/g for the susceptible colony. Insects resistant to CryIC toxin from HD-133 also were resistant to trypsinized CryIA(b), CryIC from B. thuringiensis subsp. entomocidus, CryIE-CryIC fusion protein (G27), CryIH, and CryIIA. In vitro binding experiments with brush border membrane vesicles showed a twofold decrease in maximum CryIC binding, a fivefold difference in K(infd), and no difference in the concentration of binding sites for the CryIC-resistant insects compared with those for the susceptible insects. Resistance to CryIC was significantly reduced by the addition of HD-1 spores. Resistance to the CryIC toxin was still observed 12 generations after CryIC selection was removed. These results suggest that, in S. exigua, resistance to a single protein is more likely to occur than resistance to spore-crystal mixtures and that once resistance occurs, insects will be resistant to many other Cry proteins. These results have important implications for devising S. exigua resistance management strategies in the field.

A unique insertion in the S gene of surface antigen--negative hepatitis B virus Chinese carriers

The presence of unique hepatitis B virus (HBV) variants has been investigated in two Chinese patients with chronic liver disease, whose sera were positive for HBV-DNA by dot blot hybridization or polymerase chain reaction (PCR) but hepatitis B surface antigen (HBsAg)-negative by conventional polyclonal antibody based immunoassays. PCR amplification of HBV-DNA followed by direct sequencing showed an insertion of six nucleotides, which introduced two additional amino acids between codons 122 and 123 in one patient (Isolate 1), whereas a nine nucleotide insertion in the other patient (Isolate 2) gave rise to three amino-acids between codons 123 and 124 immediately upstream from the 'a' determinant in the S gene. These insertions have not been described previously in any published sequences of the known subtypes and were absent from sequences of 30 HBsAg-positive Chinese patients from the same region. In the cases under study, the insertion is associated with four consecutive adenine molecules from nucleotides 516 to 519. It seems likely that this area is a hot spot for insertions in HBV. We found none of the previously described amino-acid deletions or substitutions in the pre-S1, pre-S2 and S genes, which are involved in unusual antigenic profiles. This finding suggests that genetic mutations in the S gene outside the 'a' determinant may be responsible for failure to detect HBsAg in some Chinese patients with chronic hepatitis caused by HBV infection.

The role of initial AIDS-defining illness in survival following AIDS

OBJECTIVE

To examine the role of initial AIDS-defining illness in survival following AIDS and survival trends over time.

DESIGN

States and Territory Health Departments notified new diagnoses of AIDS to the National AIDS Registry. Information on vital status and date of last medical contact was sought annually.

METHODS

Survival was calculated for all adult and adolescent AIDS cases (n = 3204) in Australia diagnosed until 1 November 1991 and reported to the National AIDS Registry by 31 March 1994. The Cox regression method was used to identify independent predictors for survival.

RESULTS

Age < 50 years, a CD4+ cell count > or = 100 x 10(6)/l and an initial diagnosis of Kaposi's sarcoma were independently associated with longer survival (P < 0.05). Acquisition of HIV through blood transfusion and the AIDS-defining illness non-Hodgkin's lymphoma were significantly associated with shorter survival. Survival improved substantially from 1986 to 1987, but did not improve further thereafter. A further study of initial AIDS-defining illnesses in a subgroup of individuals, i.e., men aged < 50 years at diagnosis who acquired HIV infection through homosexual or bisexual contact and diagnosed after 1987, showed that Kaposi's sarcoma, Pneumocystis carinii pneumonia, oesophageal candidiasis and herpes simplex virus as initial AIDS-defining illnesses had a relatively better prognosis than other single illnesses. Furthermore, patients with multiple illnesses did not have a worse prognosis than patients with a single illness, provided all illnesses were those with a better prognosis.

CONCLUSIONS

Initial AIDS-defining illness, as well as age at diagnosis, year of diagnosis, HIV exposure and CD4+ cell count at diagnosis, plays an important role in survival following AIDS in Australia.

HIV infection in recipients of blood products from donors with known duration of infection

From a registry of people with transfusion-acquired HIV infection, 25 recipients were identified for whom the dates of HIV infection in the 8 corresponding donors could be established. Longer times to AIDS and to death in recipients were independently associated (p < 0.01) with the receipt of blood from donors who developed AIDS more than 10 years after HIV infection, as well as with older age and fewer transfusions. Sex, zidovudine treatment, and severity of illness at transfusion were not significantly associated with survival.

Enterprise-based sheltered workshops in Nanjing. A new model for the community rehabilitation of mentally ill workers

This paper describes the development of community mental health services in Nanjing and reports on a retrospective study that compared the two-year outcome for 78 schizophrenic patients who attended four enterprise-based sheltered workshops (experimental group) with that of 78 schizophrenic patients who attended an out-patient clinic (control group). Despite having a longer course of illness and more prior hospital admissions than patients in the control group, at the end of the two years patients treated in enterprise-based sheltered workshops had significantly less psychosocial dysfunction (mean Social Dysfunction Screening Schedule score 3.4 (s.d. 0.2) v. 7.4 (s.d. 0.7), t = 49.2, d.f. 154, P < 0.001) and less severe psychiatric symptomatology (mean Brief Psychiatric Rating Scale score 33.1 (s.d. 2.7) v. 54.1 (s.d. 2.9), t = 47.0, d.f. 154, P < 0.001). Moreover, compared with the control group, over the two year period a smaller proportion of the experimental group experienced a clinical relapse (14.1% v. 38.5%, chi 2 = 5.10, d.f. 1, P < 0.05) or hospital readmission (7.7% v. 21.8%, chi 2 = 10.7, d.f. 1, P < 0.01). We conclude that the organisation of on-site sheltered workshops for mentally ill factory workers is an effective model for promoting community mental health that merits widespread application in China.

Effect of dimethylsulfoxide and hydroxyethyl starch in the preservation of fractionated human marrow cells

Fractionated human bone marrow cells, isolated by density centrifugation, could be well cryopreserved in both a DMSO/HES/albumin mixture and the conventional cryoprotectant (DMSO/serum) with either a programmed freezer or a -80 degrees C freezer. A lower initial temperature rise and a delayed plateau phase in the mixture in comparison with those in the DMSO/serum were observed using a programmed procedure without heat fusion compensation. Plateau phase in the mixture could also be shortened with increased liquid nitrogen to minimize the transition phase duration. However, the method of mononuclear cells immersed in a -80 degrees C freezer and stored in liquid nitrogen is simple and easily standardized. Additionally, widely used lactated Ringer's solution instead of Normosol-R can be employed to prepare the mixture for the preservation of fractionated cells.

Removal of Adsorbed Toxin Fragments That Modify Bacillus thuringiensis CryIC δ-Endotoxin Iodination and Binding by Sodium Dodecyl Sulfate Treatment and Renaturation

We report that 10- and 25-kDa toxin fragments adhere to CryIC prepared from Bacillus thuringiensis insecticidal crystals, block iodination, and alter membrane binding. There is no apparent affect on CryIC toxicity against Spodoptera exigua. Associated peptides remained bound to CryIC in the presence of 50 mM dithiothreitol or 6 M urea. A novel detergent-renaturation procedure was developed for the purification of B. thuringiensis CryIC toxin. Sodium dodecyl sulfate (SDS) treatment followed by gel filtration chromatography yielded a homogeneous 62-kDa CryIC toxin. After removal of SDS and renaturation, the purified CryIC toxin was fully insecticidal to S. exigua larvae. 125 I-labeled CryIC bound with high affinity to brush border membrane vesicles from S. exigua larvae.

Reversal of resistance to Bacillus thuringiensis in Plutella xylostella

Continued success of the most widely used biopesticide, Bacillus thuringiensis, is threatened by development of resistance in pests. Experiments with Plutella xylostella (diamondback moth), the first insect with field populations resistant to B. thuringiensis, revealed factors that promote reversal of resistance. In strains of P. xylostella with 25- to 2800-fold resistance to B. thuringiensis compared with unselected strains, reversal of resistance occurred when exposure to B. thuringiensis was stopped for many generations. Reversal of resistance was associated with restoration of binding of B. thuringiensis toxin CryIA(c) to brush-border membrane vesicles and with increased biotic fitness. Compared with susceptible colonies, revertant colonies had a higher proportion of extremely resistant individuals. Revertant colonies responded rapidly to reselection for resistance. Understanding reversal of resistance will help to design strategies for extending the usefulness of this environmentally benign insecticide.

[Seroepidemiological investigations on hepatitis B virus infection in the populations of Han, Tibetan, Dai, Yao, Uygur, Mongol and Li nationalities]

Seroepidemiological investigations on the hepatitis B virus infection were carried out among populations of seven nationalities that could represent the main categories by the language system. The HBsAg prevalence, after sex- and age-adjustment, was 15.3% in Han in contrast, that was 26.2% in Tibetan and 24.0% in Yao, being significantly higher (P < 0.001); and on the other hand, 7.0% in Li and 5.3% in Uygur, being significantly lower than that in Han (P < 0.001). The age peaks of HBsAg prevalence in Uygur and Li declined much earlier than others. HBeAg was not detected in women during childbearing age. The ratios of anti-HBs/HBsAg were between 1.61 and 2.06 in general while they were only 0.82 in Tibetan and 1.09 in Yao.

Activated lck tyrosine protein kinase stimulates antigen-independent interleukin-2 production in T cells

p56lck, a member of the src family of cytoplasmic tyrosine kinases, is expressed predominantly in T cells where it associates with the T-cell surface molecules CD4 and CD8. Mutants of CD4 and CD8 that have lost the ability to associate with p56lck no longer enhance antigen-induced T-cell activation. This suggests that p56lck plays an important role during T-cell activation. In an effort to understand the function of p56lck in T cells, a constitutively activated lck gene (F505lck) was introduced into T-helper hybridoma cell lines by retroviral infection. In four T-cell lines we examined, the activated lck protein stimulated interleukin-2 (IL-2) production, a hallmark of T-cell activation, in the absence of antigenic stimulation. In addition, a marked increase in antigen-independent IL-2 production was apparent when T cells infected with a temperature-sensitive F505lck were shifted to the permissive temperature. Only one cell line expressing F505lck exhibited increased sensitivity to antigenic stimulation. The SH3 domain of p56lck was dispensable for the induction of antigen-independent IL-2 production. In contrast, deletion of the majority of the SH2 domain of p56F505lck reduced its ability to induce spontaneous IL-2 production markedly. Activated p60c-src also induced antigen-independent IL-2 production, whereas two other tyrosine kinases, v-abl and the platelet-derived growth factor receptor, did not. Tyrosine phosphorylation of a 70-kDa cellular protein was observed after cross-linking of CD4 in T cells expressing F505lck but not in cells expressing F527src.

[Asymptomatic hepatitis B virus infection among the elderly]

The hepatitis B virus (HBV) infection usually occurs during infancy and children. To elucidate how the infection changes during the elderly life, 2233 residents were surveyed and among them 440 individuals with the age of 60-96 years were centered for analysis. The infection in the elderly was decreasing. HBsAg prevalence (5.0%) and titer (3.5 +/- 2.3) were getting lower, nearly all HBeAg seroconverted to anti-HBe, and the infection might be cleared at last. However, the HBV antibody prevalence steadily maintained, implying frequent HBV exposure and antibody responses during aging in the endemic area. Among them no fresh HBsAg were detected at one year follow-up, but antibodies developed in 10.8% of 65 individuals without HBV markers initially, and more, in 79 with single anti-HBs or anti-HBc 6.3% developed another antibody in a year. Therefore, the elderly population might be in a hypo-infection and dynamic hyperimmune status of the hepatitis B virus.

[Polymerase chain reaction in the detection of hepatitis B virus carriers with sole positive anti-hepatitis B core antigen]

To assess the prevalence of serum HBV DNA in the individuals with positive anti-HBc alone, seroepidemiologic investigations in three populations were carried out with polymerase chain reaction. The detection of sole anti-HBc were 21 of 294 (7.1%), 193 of 1995 (9.7%) and 23 of 377 (6.1%) individuals respectively. Among the anti-HBc positive sera, HBV DNA was detected in 6 (28.6%), 68 (35.2%) and 7 (30.4%) respectively. Follow-up observations showed that 83.8%, 93.1% and 71.4% still remained HBV DNA positive respectively. These might be reasonably regarded as chronic asymptomatic HBV carriers with undetectable HBsAg.

Transfer of proteins to membranes facilitates both cyanogen bromide cleavage and two-dimensional proteolytic mapping

We have found that the transfer of gel-fractionated proteins to membranes facilitates phosphopeptide mapping. Nitrocellulose proves to be an excellent matrix for both cyanogen bromide cleavage and proteolytic digestion. Digestion of p56lck bound to a nitrocellulose membrane with cyanogen bromide or trypsin generated patterns of phosphopeptides indistinguishable from those produced by digestion of p56lck eluted from a gel. Immobilon-P and nylon membranes can also be used for proteolytic mapping, but not for cyanogen bromide cleavage. Since the use of membrane-bound protein eliminates the need for elution and precipitation of the protein, analysis is rapid. In addition, the recovery of the peptides from proteins digested on membranes is better and more consistent than it is from eluted and precipitated proteins.

Strain differences in the ontogeny of estrogen receptors in murine uterine epithelium

The expression of estrogen receptor (ER) in the reproductive tracts of neonatal mice was examined using immunocytochemical and autoradiographic methods. Two strains of mice used in previous studies that reported contradictory results showed different rates of uterine epithelial development. In the inbred strain, BALB/c, the epithelium was devoid of receptor from birth through 5 days of age, while uterine epithelial cells of the outbred strain, CD-1, expressed ER as early as 3 days of age. Oviductal epithelium and cervical epithelium expressed ER on the day of birth in CD-1 mice. Glandular ontogeny in the uteri of CD-1 animals was also advanced by 3 days compared to that of BALB/c mice. These observations reconcile the conflicting reports of ER ontogeny in the neonatal mouse. More importantly, these results confirm our earlier observations, indicating that the cells lining uteri of 2- and 4-day-old BALB/c mice lack ER at a time when estrogen induces their proliferation.

Activators of protein kinase C induce dissociation of CD4, but not CD8, from p56lck

The CD4 and CD8 T cell receptor accessory molecules can both be isolated from T lymphocytes in association with p56lck, a membrane-associated, cytoplasmic tyrosine protein kinase that is expressed exclusively in lymphoid cells. The enzymatic activity of p56lck may therefore be regulated by CD4 and CD8 and be important in antigen-induced T cell activation. Exposure of human T cells and some mouse T cells to the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA), an activator of protein kinase C, caused the dissociation of p56lck and CD4. Activation of protein kinase C may therefore interrupt regulation of p56lck by CD4 and alter the ability of p56lck to interact with polypeptide substrates. In contrast, exposure of cells to TPA did not cause dissociation of p56lck and CD8. Regulation of p56lck by CD4 may therefore differ from regulation by CD8.