[Advances in clinical diagnosis and treatment of drug-induced liver injury in children].

Drug-induced liver injury (DILI) is one of the most common adverse drug reactions that may seriously threaten the health of children and is receiving increasing clinical attention day by day. There is still no independent diagnosis and treatment guideline for DILI in children, but its clinical features are not completely similar to those in adults. This article reviews the epidemiology, clinical features, diagnosis, and treatment progress in order to provide a reference for the management of DILI in children.

[Clinicopathological and molecular genetic characteristics of nodular fasciitis in unusual sites].

Objective: To study the clinicopathological, immunophenotypic and molecular genetic characteristics of nodular fasciitis (NF) in unusual sites. Methods: A total of 50 cases of NF diagnosed between January 2015 and January 2021 were reviewed in the Department of Pathology, Henan Provincial People's Hospital, and the clinical and pathologic data were analyzed. Among them, 14 cases from unusual sites were included in this study. Immunohistochemical (IHC) staining was used to detect the expression of related proteins, and fluorescence in situ hybridization (FISH) was used to detect the breakage of the USP6 gene. Results: There were seven males and seven females in the 14 NF respectively. The lesions were located in the extremities, perineum, breast, wrist joints, the gap between lumbar vertebra 4/5, and in eight cases there was involvement of unusual tissues (six cases in skeletal muscle, one case in nerve root, and one case was intravascular). The tumor boundary was unclear with infiltrating growth. Spindle-shaped myofibroblasts were arranged in bundles or chaotically, with mild pleomorphic, small nucleoli and various mitotic figures. The tumor stroma showed collagenization to myxoid degeneration with erythrocyte extravasation and infiltration of inflammatory cells. IHC staining showed that the spindle cells expressed SMA focally or partially, and p16 diffusely and strongly. FISH showed that 12 of 14 cases had USP6 gene breakage, and two of them occurred in the intrathoracic skeletal muscle with the red signal amplification of USP6 gene. Conclusions: NF in unusual sites shows similar clinicopathological and genetic characteristics to classic NF, but the tumor mostly has infiltrating borders, non-specific and strong expression of p16, and USP6 red signal amplification. The pathological diagnosis of NF in rare sites should be highly vigilant.

[Clinical effect and influencing factors of pegylated interferon alfa-2a and entecavir monotherapy among children with HBeAg-positive chronic hepatitis B based on a real-world study].

Objective: To compare the efficacy, safety, and influencing factors among children with hepatitis B virus e antigen (HBeAg)-positive chronic hepatitis B (CHB) who received short-term therapy with pegylated interferon alfa-2a (Peg-IFNα-2a) or continuous therapy with entecavir (ETV). Methods: Quantitative data were compared using analysis of variance to compare the differences between groups. Enumeration data were compared by χ2 test (or Fisher's exact test). Univariate and multivariate logistic regressions were used to analyze the influencing factors. Results: Peg-IFNα-2a, ETV, and untreated group had HBsAg clearance rates of 46.2%, 5.3%, and 0 after 52 weeks of therapy, respectively. HBsAg clearance in the patients' group with Peg-IFNα-2a and ETV was all accompanied by anti-HBS positive conversion, and the difference was statistically significant (χ2=13.616, P=0.001). Peg-IFNα-2a group was followed-up for 104 weeks. Peg-IFNα-2a, ETV, and the untreated group had HBsAg clearance rates of 46.2%, 10.5%, and 0%, respectively, and the differences were statistically significant (χ2=11.056, P=0.004). Only one of the two children with HBsAg clearance in the ETV group had achieved anti-HBs antibodies, and the difference was statistically significant (χ2=13.616, P=0.001). Univariate and multivariate logistic regression analysis showed that HBsAg clearance was associated with age and antiviral therapy. During treatment, adverse events such as fever (n=4, 30.8%), rash (n=4, 30.8%), fatigue (n=1, 7.7%), leukopenia (n=7, 53.8%), arthritis (n=1, 7.7%), and alopecia (n=3, 23.1%) were observed in the Peg-IFNα-2a group, while none were observed in the ETV group. Conclusion: Peg-IFNα-2a antiviral therapy produced higher HBsAg clearance than ETV in five-year-old and younger children with HBeAg-positive CHB, while ETV had fewer adverse events and was safer than Peg-IFNα-2a.

[Progress in diagnosis and treatment of viral hepatitis in children].

Hepatitis B and C virus infections are major global public health problem and economic burden. Most children with vertical infection have asymptomatic hepatitis, but the risk of chronic viral hepatitis and further development of liver cirrhosis or hepatocellular carcinoma is higher. Over the past two to three decades, with the rapid development of detection technology and the continuous research and development of antiviral drugs, great progress has been made in the diagnosis and treatment of viral hepatitis caused by hepatitis B and C infection. However, due to the particularity of its characteristics, it is still necessary to carefully judge and evaluate the diagnosis and antiviral treatment of children. This article focuses on the difficulties in the diagnosis and treatment of viral hepatitis in children, and summarizes its progress.

[Analysis of liver pathological characteristics and exploration of noninvasive markers of liver fibrosis in children with chronic hepatitis B].

Objective: To analyze and summarize the characteristics of liver pathology and their relation to clinical markers and further explore noninvasive markers of liver fibrosis in children with chronic hepatitis B. Methods: Data of 80 hospitalized children with chronic hepatitis B who underwent liver biopsy without antiviral treatment from 2011 to 2020 were retrospectively analyzed. Inflammation and liver fibrosis characteristics were analyzed in children of different ages and genders. Variables with good correlation with liver fibrosis stage were selected to establish a non-invasive diagnostic score of liver fibrosis in children. Measurement data was used to compare the t-test or rank sum test. Mantel-Haenszel χ (2) test was used for bidirectional ordered grouping data. Spearman's rank correlation test was used for rank correlation analysis. Receiver operating characteristic curve (ROC) was used to evaluate the diagnostic value of the newly established diagnostic score in children with liver fibrosis. Results: The median age of the children was 6.4 years. HBV DNA level was high (P50 = 7.6 log(10) IU/ml), and serum alanine aminotransferase (ALT) in P50 was 171 U/L (< ULN: 5 cases, ULN-2ULN: 10 cases, > 2 ULN: 65 cases). Pathological analysis showed that the incidence of liver tissue inflammation was 97.5%, and the proportion of patients with G≥2 was 42.5%, while S≥2 was 36.3%. The incidence rate of liver fibrosis and liver cirrhosis was 81.3%, and 1.3%, respectively. The changes in liver tissue inflammation and fibrosis were gradually aggravated with the increase of age, and the proportion of high-grade inflammation and liver fibrosis in male children was higher than that in female children. Serum levels of glutamyl transpeptidase (GGT), γ-glutamyltransferase/platelet ratio (GPR) and HBeAg had a good correlation with fibrosis stage (r(s) = 0.397, 0.389, and - 0.311) in children with chronic hepatitis B. The combination of GGT, GPR and HBeAg can establish a non-invasive diagnostic score for evaluating liver fibrosis in children. When the score is less than 1.5, it can be diagnosed as S0, and 1.5 ≤ score < 3.5, it can be diagnosed as S1; 3.5 ≤ score < 5.5, the diagnosis of fibrosis is S2; score≥ 5.5, the diagnosis of fibrosis is S≥3. The sensitivity and specificity were 80%, 83%, 86%, and 53%, 55%, 67%, respectively. Conclusion: The incidence of liver tissue inflammation in children with chronic hepatitis B with elevated and fluctuating transaminase levels is high, and the pathological changes of liver tissue aggravate with the age of the children. GGT, GPR and HBeAg have a good correlation with liver fibrosis in children with chronic hepatitis B. Therefore, combining the above-mentioned markers to establish a new noninvasive diagnostic score has certain diagnostic value for liver fibrosis stage S0-S3 in children with chronic hepatitis B.

[Correlation of qAnti-HBc with antiviral efficacy in children with chronic hepatitis B and exploration of its possible immune mechanism].

Objective: To compare the baseline difference in the quantitative hepatitis B core antibody levels (qAnti-HBc) between non-response and response group in children with HBeAg-positive chronic hepatitis B (CHB) who received antiviral therapy, and further explore the proportion and functional activity of CD8 + memory T lymphocyte subsets with different qAnti-HBC levels in peripheral blood of children. Methods: The baseline anti-HBc quantification (qAnti-HBc) levels of 85 children with HBeAg-positive CHB who visited the Department of Infectious Diseases, Children's Hospital of Chongqing Medical University from June 2018 to December 2020 were detected retrospectively. The relationship between the baseline qAnti-HBc level and HBeAg serological response in 37 children who received antiviral therapy was analyzed. The proportion of CD8(+) memory T lymphocyte subsets and the secretion levels of interferon (IFN) γ, and tumor necrosis factor (TNF) α in peripheral blood of 59 children at baseline were detected by flow cytometry. The relationship between qAnti-HBc level and the proportion and functional activity of CD8(+) memory T lymphocyte subsets was analyzed. Pearson's Chi-square test was used to compare the count data. Mann-Whitney U test or Kruskal-Wallis test was used to compare measurement data between two or more groups, and Spearman's rank correlation analysis was used for the correlation between continuous variables. Results: Among 37 children who received entecavir (ETV, 21/37 cases) or pegylated interferon (Peg-IFN, 16/37 cases), 18 cases had developed HBeAg seroconversion (10/ 21 cases in the ETV group, 8/16 cases in the Peg-IFN group). The baseline qAnti-HBc level was significantly higher in the response group [4.71 (4.64~4.81) log(10)IU/ml] than the non-response group children [4.54 (4.45~4.64) log(10)IU/ml, Z = -3.316, P = 0.001]. The proportion of CD8(+) Tem, CD38(+)CD8(+) Tem, CD38(+)CD8(+) Temra cells and the levels of IFNγ and TNFα secreted by CD8(+) T lymphocytes were significantly higher in the high-qAnti-HBc group than the low-qAnti-HBc group (P < 0.05). The proportion of CD8(+) Tem, CD38(+)CD8(+) Tem and CD38(+)CD8(+) Temra cells was significantly higher in ALT > 1× upper limit of normal value (ULN) group than ALT≤1×ULN group (P < 0.05). However, there were no significant differences in the levels of IFNγ and TNFα secreted by CD8(+) T lymphocytes between the two groups (P > 0.05). Spearman's correlation analysis showed that qAnti-HBc was positively correlated with the proportion of CD8(+) Tem, CD38(+)CD8(+) Tem, CD38(+)CD8(+) Temra cells and the level of IFNγ secreted by CD8(+)T lymphocytes (P < 0.05). Additionally, ALT was only positively correlated with the proportion of CD38(+)CD8(+) TEM and CD38(+) CD8(+) Temra cells (P < 0.05). Conclusion: Raised baseline qAnti-HBc level is related to the HBeAg serological response to antiviral therapy in children with CHB. Peripheral blood effector CD8+ T lymphocytes of CHB children with higher qAnti-HBc show stronger phenotype and functional activation characteristics, which may shed some light on the underlying immune mechanism related to antiviral therapy efficacy in children with CHB.

Alzheimer's disease: insights for risk evaluation and prevention in the Chinese population and the need for a comprehensive programme in Hong Kong/China.

With the ageing of the global population, China is projected to be impacted significantly by the rising number of patients with Alzheimer's disease (AD). A cure for AD is not yet available, so society should be prepared for an increasing AD-related burden. In this review, we examine this impending problem and provide overviews on (a) the magnitude of the problem of AD in Hong Kong/China in the near future; (b) the genetic and lifestyle risk factors that contribute to AD; (c) current diagnostic approaches and the potential of newly discovered genetic biomarkers for early detection; (d) medications, non-pharmacological interventions, and possible preventive measures; and (e) the need for social and psychological care from the community. In Hong Kong, primary care and AD-related support for at-risk individuals, patients, and caregivers are inadequate. A joint effort from the medical community, government, universities, non-governmental organisations/charities, and industry should initiate the development of a long-term programme for AD. Finally, we outline recommendations for the relevant parties to consider.

[Clinical characteristics of 11 patients with chronic lymphocytic leukemia with t (14;19) (q32;q13)].

Objective: To analyze the clinicopathological characteristics of 11 cases of chronic lymphocytic leukemia (CLL) with t (14;19) (q32;q13) . Methods: The case data of 11 patients with CLL with t (14;19) (q32;q13) in the chromosome karyotype analysis results of the Blood Diseases Hospital, Chinese Academy of Medical Sciences from January 1, 2018, to July 30, 2022, were retrospectively analyzed. Results: In all 11 patients, t (14;19) (q32;q13) involved IGH::BCL3 gene rearrangement, and most of them were accompanied by +12 or complex karyotype. An immunophenotypic score of 4-5 was found in 7 patients and 3 in 4 cases. We demonstrated that CLLs with t (14;19) (q32;q13) had a mutational pattern with recurrent mutations in NOTCH1 (3/7), FBXW7 (3/7), and KMT2D (2/7). The very-high-risk, high-risk, intermediate-risk, and low-risk groups consisted of 1, 1, 6, and 3 cases, respectively. Two patients died, 8 survived, and 2 were lost in follow-up. Four patients had disease progression or relapse during treatment. The median time to the first therapy was 1 month. Conclusion: t (14;19) (q32;q13), involving IGH::BCL3 gene rearrangement, is a rare recurrent cytogenetic abnormality in CLL, which is associated with a poor prognosis.

Dopaminergic neurons protected from degeneration by GDNF gene therapy.

Glial cell line-derived neurotrophic factor (GDNF) supports growth and survival of dopaminergic (DA) neurons. A replication-defective adenoviral (Ad) vector encoding human GDNF injected near the rat substantia nigra was found to protect DA neurons from the progressive degeneration induced by the neurotoxin 6-hydroxydopamine (6-OHDA) injected into the striatum. Ad GDNF gene therapy reduced loss of DA neurons approximately threefold 6 weeks after 6-OHDA lesion, as compared with no treatment or injection of Ad lacZ or Ad mGDNF (encoding a biologically inactive deletion mutant GDNF). These results suggest that Ad vector-mediated GDNF gene therapy may slow the DA neuronal cell loss in humans with Parkinson's disease.

Paclitaxel chemotherapy after autologous stem-cell transplantation and engraftment of hematopoietic cells transduced with a retrovirus containing the multidrug resistance complementary DNA (MDR1) in metastatic breast cancer patients.

The MDR1 multidrug resistance gene confers resistance to natural-product anticancer drugs including paclitaxel. We conducted a clinical gene therapy study to determine whether retroviral-mediated transfer of MDR1 in human hematopoietic cells would result in stable engraftment, and possibly expansion, of cells containing this gene after treatment with myelosuppressive doses of paclitaxel. Patients with metastatic breast cancer who achieved a complete or partial remission after standard chemotherapy were eligible for the study. Hematopoietic stem cells (HSCs) were collected by both peripheral blood apheresis and bone marrow harvest after mobilization with a single dose of cyclophosphamide (4 g/m2) and daily filgrastim therapy (10 microg/kg/day). After enrichment for CD34+ cells, one-third of each collection was incubated ex vivo for 72 h with a replication-incompetent retrovirus containing the MDR1 gene (G1MD) in the presence of stem-cell factor, interleukin 3, and interleukin 6. The remaining CD34+ cells were stored without further manipulation. All of the CD34+ cells were reinfused for hematopoietic rescue after conditioning chemotherapy with ifosfamide, carboplatin, and etoposide regimen. After hematopoietic recovery, patients received six cycles of paclitaxel (175 mg/m2 every 3 weeks). Bone marrow and serial peripheral blood samples were obtained and tested for the presence of the MDR1 transgene using a PCR assay. Six patients were enrolled in the study and four patients received infusion of genetically altered cells. The ex vivo transduction efficiency, estimated by the PCR assay, ranged from 0.1 to 0.5%. Three of the four patients demonstrated engraftment of cells containing the MDR1 transgene. The estimated percentage of granulocytes containing the MDR1 transgene ranged from a maximum of 9% of circulating nucleated cells down to the limit of detection of 0.01%. One patient remained positive for the MDR1 transgene throughout all six cycles of paclitaxel therapy, whereas the other 2 patients showed a decrease in the number of cells containing the transgene to undetectable levels. Despite the low level of engraftment of MDR1-marked cells, a correlation was observed between the relative number of granulocytes containing the MDR1 transgene and the granulocyte nadir after paclitaxel therapy. No adverse reactions to the genetic manipulation procedures were detected. Therefore, engraftment of human HSCs transduced with the MDR1 gene can be achieved. However, the overall transduction efficiency and stable engraftment of gene-modified HSCs must be improved before MDR1 gene therapy and in vivo selection with anticancer drugs can be reliably used to protect cancer patients from drug-related myelosuppression.

Effect of herpes simplex virus thymidine kinase expression levels on ganciclovir-mediated cytotoxicity and the "bystander effect".

Transfer of the herpes simplex virus type-1 thymidine kinase (HSV-tk) gene into tumor cells followed by ganciclovir (GCV) administration, will provide selective tumor cell killing. We studied the effect of herpes simplex virus thymidine kinase (HSV-tk) expression level on the HSV-tk/GCV-mediated "bystander effect." Clones of HSV-tk-transduced rat glioma cells (9L) were isolated that stably expressed with different levels of HSV-tk. All clones studied had similar sensitivity to ganciclovir with IC50 values ranging from 0.45 to 1.3 microM. Within certain enzyme level thresholds, in vitro evaluation of the bystander effect has shown that clones with higher level of HSV-tk expression exhibited a better bystander effect. Interestingly, the bystander effect was observed between different cell types. Both the transduction efficiency and bystander effect are essential factors for the success of the antitumor effect by the HSV-tk/prodrug GCV suicide gene system.

A novel tumor-specific replication-restricted adenoviral vector for gene therapy of hepatocellular carcinoma.

Transducing and distributing a vector throughout a tumor mass are presently insufficient for effective cancer gene therapy. To overcome these difficulties an adenoviral vector was designed that would replicate specifically in tumor cells. This tumor-specific replication-restricted adenoviral (TSRRA) vector was constructed by requiring that the essential E1A gene be expressed from a tumor-specific promoter, namely, the alpha-fetoprotein (AFP) gene promoter. This promoter was chosen since the AFP gene is highly expressed in 70-80% of patients with hepatocellular carcinoma (HCC) but not in normal adults. HCC is one of the major worldwide causes of cancer death. A vector was constructed (AvE1a04i) and demonstrated to replicate in human AFP-producing HCC cell lines. However, little replication was observed in seven other, non-AFP-producing human cell lines, as well as primary cultures of normal human lung epithelial and endothelial cells. In addition, AvE1a04i was shown to prevent tumor growth of an ex vivo-transduced AFP-expressing HCC cell line but not a non-AFP-expressing cell line. Finally, in situ administration of AvE1a04i into preestablished tumors resulted in a greater than 50% long-term survival rate. This novel TSRRA vector for HCC demonstrated both specificity and efficacy in vitro and in vivo.

Nucleotide sequence and transcription of a human tRNA gene cluster with four genes.

A bacteriophage lambda clone containing a 20-kb human DNA segment was isolated and found to harbor a cluster of four tRNA genes. An 8.2-kb HindIII subfragment encompassing the genes was cloned into pBR322 for restriction mapping and DNA sequence analysis. The genes were found to be arranged as two tandem pairs, separated by 3 kb. A proline tRNAAGG gene is separated from a leucine tRNAAAG gene by a 724-bp intergenic region in the first pair, and a second proline tRNAAGG gene is 316 bp from a threonine tRNAUGU gene in the second pair, with the leucine tRNA gene being of opposite polarity to the other three genes. A putative Alu-like element was found to occur within a 2.0-kb DNA fragment, at least 0.7 kb from the tRNA gene cluster. The coding sequences of the two proline tRNAAGG genes are identical. The coding regions of all four tRNA genes contain consensus internal split promoter sequences and do not have intervening sequences nor the CCA trinucleotide found in mature tRNAs. The 3'-flanking regions of these four tRNA genes have normal RNA polymerase III termination sites of at least four consecutive T nucleotides. No apparent homologies occur between the 5'-flanking regions of these genes. All four tRNA genes are accurately transcribed in an in vitro HeLa cell-free system, and the RNase T1 fingerprints of the mature-sized tRNA transcripts were found to be consistent with the DNA sequences of the genes.

A human DNA segment encompassing leucine and methionine tRNA pseudogenes localized on chromosome 6.

A human genomic clone, designated LHtlm8, that strongly hybridized to a mammalian leucine tRNA(IAG) probe, was found to encompass a pair of tRNA pseudogenes that are transcribed in a homologous cell extract. A leucine tRNA(AAG) pseudogene (TRLP1) is 2.1-kb upstream and of opposite polarity to a methionine elongator tRNA(CAU) pseudogene (TRMEP1). TRLP1 has three nucleotide variations (97% identity) from its cognate leucine tRNA(IAG), while TRMEP1 has a 78% identity with its cognate tRNA. Similar to a number of other eukaryotic tRNA pseudogenes, presumptive precursor tRNA transcripts are generated from the two pseudogenes in vitro, but possibly due to their aberrant and unstable secondary and tertiary structures, no detectable mature tRNA products are observed. The two tRNA pseudogenes are encompassed within a 9.6-kb EcoRI fragment that has been assigned to the chromosomal locus, 6pter-q13, by Southern blot hybridization of human-rodent somatic cell hybrid DNAs with probes derived from the cloned tRNA pseudogenes and flanking sequences. A 4.4-kb EcoRI fragment also harbored in clone LHtlm8 was mapped to human chromosome 11, suggesting that the two EcoRI fragments were inadvertantly ligated together during construction of the genomic library.

Dual cytotoxic mechanisms of submicromolar taxol on human leukemia HL-60 cells.

Taxol-induced mitotic block and apoptosis were investigated using taxol-sensitive human leukemia HL-60 cells at submicromolar concentrations of the drug. Cells exposed to either 20 nM taxol for 1 hr or 10 nM taxol for 12 hr were able to resume normal growth, whereas cells exposed to 60 nM taxol for 1 hr or 10 nM taxol for 24 hr failed to proliferate after drug removal. Progressive changes in the percentage of mitotic block and apoptosis induced by these four treatment protocols were monitored continuously for 3-5 days after drug removal. Cells treated with 20 nM taxol for 1 hr showed a mitotic block without a subsequent increase in apoptosis, whereas cells treated with 10 nM taxol for 12 hr showed an increase in apoptotic ratio within several hours without an increase in mitotic block. These results indicate that apoptosis does not necessarily result from mitotic block and that these two phenomena can occur independently of each other. Drug sensitivity at progressive stages of the cell cycle was also investigated. The results showed that, in addition to the cells in G2/M phase, the cells in S phase were also sensitive to the drug, especially to a prolonged treatment. These results suggest that, in HL-60 cells, the apoptotic programs can be initiated in either the G2/M or S phase and represent two different cytotoxic mechanisms of taxol.

Structural Organization of the Spliced Immediate-Early Gene Complex that Encodes the Major Acidic Nuclear (IE1) and Transactivator (IE2) Proteins of African Green Monkey Cytomegalovirus.

Total immediate-early (IE) RNA synthesized after infection with African green monkey cytomegalovirus (SCMV) in the presence of cycloheximide contained a major 2.3-kb mRNA species that acted as template for in vitro synthesis of a single 94-kD nuclear protein. The same IE RNA hybridized predominantly to a 1.8-kb subregion of the 220-kb genome which mapped 1.5 kb to the left of the in vitro transcription start site and TATATAA motif previously associated with the powerful MIE (IE94) enhancer region. However, DNA sequence and S1-mapping analysis of a 5-kb region downstream from the promoter revealed the existence of a far upstream noncoding first exon and four additional spliced exons capable of encoding two alternative protein products with shared N-terminal domains. This region is similar in structure to that of the MIE gene complex of human cytomegalovirus (HCMV), including being highly CpG suppressed. Exons 2, 3, and 4 encode an acidic protein equivalent to the 68-kD IE1 protein (UL123) of HCMV and exons 2, 3, and 5 encode a protein equivalent to the 80-kD IE2 (UL122) DNA-binding protein of HCMV. Transcripts from across the IE2 region were detected within the cycloheximide RNA, but they were present at 10- to 20-fold lower abundance than IE1 transcripts. The proposed 547-codon IE1 (IE94) acidic phosphoprotein of SCMV displays minimal residual homology with the IE1 protein of HCMV, but both associate with metaphase chromosomes and have large C-terminal glutamic-acid-rich domains. In contrast, the proposed 583-codon IE2 protein of SCMV displays extensive amino acid similarity to the HCMV IE2 transcriptional regulatory protein especially within C-terminal domains that are known to play a major role in promoter targeting for both transactivation and negative autoregulation functions. Copyright 1995 S. Karger AG, Basel

Prostaglandin E1 and dibutyryl cyclic AMP enhance platelet resistance to deformation.

The effect of prostaglandin E1 (PGE1) on platelets is mediated through the PGE1 receptor and the consequent maintenance of the platelet's discoid shape. The effects of PGE1 and dibutyryl cAMP (dbcAMP) on the deformability of human platelets were studied. Deformability tests based upon the micropipette aspiration on the platelets were performed by using pipettes with radii (Rp) of 0.26-0.36 microns. The time course of the extension length (Dp, in microns) of the platelets in response to aspiration with a negative pressure (delta P) of 5 cm H2 O (delta P x Rp = 0.15 dynes/cm) was analyzed. PGE1 treatment (0.1 microM) resulted in a decrease of platelet deformability as compared with results obtained for apparently non-activated, control platelets. The deformation index, i.e., Dp/Rp (PGE1-treated)/Dp/Rp (control), was significantly reduced to 0.90 +/- 0.04. DbcAMP treatment also significantly decreased the deformability of platelets and this decrease was dbcAMP dose dependent. In contrast, colchicine- or cytochalasin D-treated platelets increased deformability. PGE1-treated platelets had a higher [cAMP]i than controls. Platelets treated with PGE1 or dbcAMP showed a reduced [Ca2+]i increment induced by thrombin as compared to non-treated controls. These results indicate that PGE1 and dbcAMP treatment of platelets is accompanied by an enhancement of platelet resistance to deformation. The increased [cAMP]i and low [Ca2+]i after PGE1 treatment may limit the rearrangement of cytoskeleton and thus enhance platelet resistance to deformation.

Sequential steps in Tat trans-activation of HIV-1 mediated through cellular DNA, RNA, and protein binding factors.

The regulation of HIV expression is controlled by the activity of the Long Terminal Repeat (LTR). Trans-activation by the virally encoded Tat protein is one of the main mechanisms of LTR activation. Tat binds to its target, TAR RNA, and cellular proteins that bind the LTR, Tat, or TAR RNA are important components of the trans-activation process. We will review the factors that have been characterized for a possible involvement in this mechanism. Whereas LTR binding proteins consist of Sp1 and TBP, a large number of factors that bind TAR RNA have been isolated. We have previously cloned two of them by RNA probe recognition: TRBP and La. We have shown that the in vitro and in vivo binding of TRBP to TAR RNA correlates with a constant expression of the protein during HIV-1 infection. Several proteins that interact with Tat have mainly positive, but some negative, effects on trans-activation. Genetic studies have defined that human chromosome 12 encodes a protein that will allow trans-activation in rodent cells. The binding and the functional data about these proteins suggest sequential steps for the Tat trans-activation mechanism. Each of these intracellular molecular events could be the target for molecular intervention against the virus.