[Antitumor effects of redox-responsive nanoparticles containing platinum（Ⅳ）in ovarian cancer]

Objectives: To explore the antitumor effects of redox-responsive nanoparticles containing platinum(Ⅳ)-NP@Pt(Ⅳ) in ovarian cancer. Methods: Redox-responsive polymer carriers were synthesized. Polymer carriers and platinum(Ⅳ)-Pt(Ⅳ) can self-assemble into NP@Pt(Ⅳ). Inductively coupled plasma mass spectrometry was performed to detect the platinum release from NP@Pt(Ⅳ) in reducing environment and the platinum content in ovarian cancer cells ES2 treated with cisplatin, Pt(Ⅳ) and NP@Pt(Ⅳ). The proliferation ability of the ovarian cancer cells were detected by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cellular apoptosis was assessed by flow cytometry. Collection of primary ovarian cancer tissues from patients with primary high-grade serous ovarian cancer who were surgically treated at the Cancer Hospital of the Chinese Academy of Medical Sciences from October to December 2022. The high-grade serous ovarian cancer patient-derived xenograft (PDX) mice were intravenously injected with Cy7.5 labeled NP@Pt(Ⅳ) followed by in vivo imaging system. Mice were treated with PBS, cisplatin and NP@Pt(Ⅳ). Tumor volume and weight were measured in each group. Necrosis, apoptosis and cell proliferation of tumor tissues were detected by hematoxylin-eosin (HE) staining, TUNEL fluorescence staining and Ki-67 immunohistochemistry staining. Body weight and HE staining of heart, liver, spleen, lung and kidney of mice in each group were measured. Results: The platinum release of NP@Pt(Ⅳ) after 48 hours in reducing environment was 76.29%, which was significantly higher than that of 26.82% in non-reducing environment (P<0.001). The platinum content in ES2 cells after 4 hours and 7 hours of treatment with NP@Pt(Ⅳ) (308.59, 553.15 ng/million cells) were significantly higher than those of Pt(Ⅳ) (100.21, 180.31 ng/million cells) and cisplatin (43.36, 50.36 ng/million cells, P＜0.05). The half inhibitory concentrations of NP@Pt(Ⅳ) in ovarian cancer cells ES2, A2780, A2780DDP were 1.39, 1.42 and 4.62 μmol/L, respectively, which were lower than those of Pt(IV) (2.89, 7.27, and 16.74 μmol/L) and cisplatin (5.21, 11.85, and 71.98 μmol/L). The apoptosis rate of ES2 cells treated with NP@Pt(Ⅳ) was (33.91±3.80)%, which was significantly higher than that of Pt(Ⅳ) [(16.28±2.41)%] and cisplatin [(15.01±1.17)%, P＜0.05]. In high-grade serous ovarian cancer PDX model, targeted accumulation of Cy7.5 labeled NP@Pt(Ⅳ) at tumor tissue could be observed. After the treatment, the tumor volume of mice in NP@Pt(IV) group was (130±98) mm3, which was significantly lower than those in control group [(1 349±161) mm3, P<0.001] and cisplatin group [(715±293) mm3, P=0.026]. The tumor weight of mice in NP@Pt(IV) group was (0.17±0.09)g, which was significantly lower than those in control group [(1.55±0.11)g, P<0.001] and cisplatin group [(0.82±0.38)g, P=0.029]. The areas of tumor necrosis and apoptosis in mice treated with NP@Pt(Ⅳ) were higher than those in mice treated with cisplatin. Immunohistochemical staining revealed that there were low expressions of Ki-67 at tumor tissues of mice treated with NP@Pt(Ⅳ) compared with cisplatin. The change in body weight of mice in NP@Pt(Ⅳ) group was not significantly different from that of the control group [(18.56±2.04)g vs.(20.87±0.79)g, P=0.063]. Moreover, the major organs of the heart, liver, spleen, lung, and kidney were also normal by HE staining. Conclusion: Redox-responsive NP@Pt(Ⅳ), produced in this study can enhance the accumulation of cisplatin in ovarian cancer cells and improve the efficacy of ovarian cancer chemotherapy.

Targeting autophagy in Alzheimer's disease: Animal models and mechanisms

Alzheimer's disease (AD) is an age-related progressive neurodegenerative disorder that leads to cognitive impairment and memory loss. Emerging evidence suggests that autophagy plays an important role in the pathogenesis of AD through the regulation of amyloid-beta (Aβ) and tau metabolism, and that autophagy dysfunction exacerbates amyloidosis and tau pathology. Therefore, targeting autophagy may be an effective approach for the treatment of AD. Animal models are considered useful tools for investigating the pathogenic mechanisms and therapeutic strategies of diseases. This review aims to summarize the pathological alterations in autophagy in representative AD animal models and to present recent studies on newly discovered autophagy-stimulating interventions in animal AD models. Finally, the opportunities, difficulties, and future directions of autophagy targeting in AD therapy are discussed.

Production of MSTN knockout porcine cells using adenine base-editing-mediated exon skipping

Gene-knockout pigs have important applications in agriculture and medicine. Compared with CRISPR/Cas9 and cytosine base editing (CBE) technologies, adenine base editing (ABE) shows better safety and accuracy in gene modification. However, because of the characteristics of gene sequences, the ABE system cannot be widely used in gene knockout. Alternative splicing of mRNA is an important biological mechanism in eukaryotes for the formation of proteins with different functional activities. The splicing apparatus recognizes conserved sequences of the 5' end splice donor and 3' end splice acceptor motifs of introns in pre-mRNA that can trigger exon skipping, leading to the production of new functional proteins, or causing gene inactivation through frameshift mutations. This study aimed to construct a MSTN knockout pig by inducing exon skipping with the aid of the ABE system to expand the application of the ABE system for the preparation of knockout pigs. In this study, first, we constructed ABEmaxAW and ABE8eV106W plasmid vectors and found that their editing efficiencies at the targets were at least sixfold and even 260-fold higher than that of ABEmaxAW by contrasting the editing efficiencies at the gene targets of endogenous CD163, IGF2, and MSTN in pigs. Subsequently, we used the ABE8eV106W system to realize adenine base (the base of the antisense strand is thymine) editing of the conserved splice donor sequence (5'-GT) of intron 2 of the porcine MSTN gene. A porcine single-cell clone carrying a homozygous mutation (5'-GC) in the conserved sequence (5'-GT) of the intron 2 splice donor of the MSTN gene was successfully generated after drug selection. Unfortunately, the MSTN gene was not expressed and, therefore, could not be characterized at this level. No detectable genomic off-target edits were identified by Sanger sequencing. In this study, we verified that the ABE8eV106W vector had higher editing efficiency and could expand the editing scope of ABE. Additionally, we successfully achieved the precise modification of the alternative splice acceptor of intron 2 of the porcine MSTN gene, which may provide a new strategy for gene knockout in pigs.

CRISPR/Cas9-mediated MSTN disruption accelerates the growth of Chinese Bama pigs

CRISPR/Cas9-mediated genome editing technology is a simple and highly efficient and specific genome modification approach with wide applications in the animal industry. CRISPR/Cas9-mediated genome editing combined with somatic cell nuclear transfer rapidly constructs gene-edited somatic cell-cloned pigs for the genetic improvement of traits or simulation of human diseases. Chinese Bama pigs are an excellent indigenous minipig breed from Bama County of China. Research on genome editing of Chinese Bama pigs is of great significance in protecting its genetic resource, improving genetic traits and in creating disease models. This study aimed to address the disadvantages of slow growth and low percentage of lean meat in Chinese Bama pigs and to knock out the myostatin gene (MSTN) by genome editing to promote growth and increase lean meat production. We first used CRISPR/Cas9-mediated genome editing to conduct biallelic knockout of the MSTN, followed by somatic cell nuclear transfer to successfully generate MSTN biallelic knockout Chinese Bama pigs, which was confirmed to have significantly faster growth rate and showed myofibre hyperplasia when they reached sexual maturity. This study lays the foundation for the rapid improvement of production traits of Chinese Bama pigs and the generation of gene-edited disease models in this breed.

Signal transduction mechanism for glucagon-induced leptin gene expression in goldfish liver

Leptin is a peripheral satiety hormone that also plays important roles in energy homeostasis in vertebrates ranging from fish to mammals. In teleost fish, however, the regulatory mechanism for leptin gene expression still remains unclear. In this study, we found that glucagon, a key hormone in glucose homeostasis, was effective at elevating the leptin-AI and leptin-AII transcript levels in goldfish liver via both in vivo intraperitoneal injection and in vitro cells incubation approaches. The responses of leptin-AI and leptin-AII mRNA to glucagon treatment were highly comparable. In contrast, blockade of local glucagon action could reduce the basal and induced leptin-AI and leptin-AII mRNA expression. The stimulation of leptin levels by glucagon was caused by the activation of adenylate cyclase (AC)/cyclic-AMP (cAMP)/ protein kinase A (PKA), and probably cAMP response element-binding protein (CREB) cascades. Our study described the effect and signal transduction mechanism of glucagon on leptin gene expression in goldfish liver, and may also provide new insight into leptin as a mediator in the regulatory network of energy metabolism in the fish model.

Goldfish Leptin-AI and Leptin-AII: Function and Central Mechanism in Feeding Control

In mammals, leptin is a peripheral satiety factor that inhibits feeding by regulating a variety of appetite-related hormones in the brain. However, most of the previous studies examining leptin in fish feeding were performed with mammalian leptins, which share very low sequence homologies with fish leptins. To elucidate the function and mechanism of endogenous fish leptins in feeding regulation, recombinant goldfish leptin-AI and leptin-AII were expressed in methylotrophic yeast and purified by immobilized metal ion affinity chromatography (IMAC). By intraperitoneal (IP) injection, both leptin-AI and leptin-AII were shown to inhibit the feeding behavior and to reduce the food consumption of goldfish in 2 h. In addition, co-treatment of leptin-AI or leptin-AII could block the feeding behavior and reduce the food consumption induced by neuropeptide Y (NPY) injection. High levels of leptin receptor (lepR) mRNA were detected in the hypothalamus, telencephalon, optic tectum and cerebellum of the goldfish brain. The appetite inhibitory effects of leptins were mediated by downregulating the mRNA levels of orexigenic NPY, agouti-related peptide (AgRP) and orexin and upregulating the mRNA levels of anorexigenic cocaine-amphetamine-regulated transcript (CART), cholecystokinin (CCK), melanin-concentrating hormone (MCH) and proopiomelanocortin (POMC) in different areas of the goldfish brain. Our study, as a whole, provides new insights into the functions and mechanisms of leptins in appetite control in a fish model.

Cloning and sequencing of the rDNA gene family of the water buffalo (Bubalus bubalis)

The rDNA genes coding for ribosomal RNA in animals are complicated repeat sequences with high GC content. We amplified water buffalo rDNA gene sequences with the long and accurate (LA) PCR method, using LA Taq DNA polymerase and GC buffer, based on bioinformatic analysis of related organisms. The rDNA genes were found to consist of 9016 nucleotides, including three rRNA genes and two internal transcribed spacers (ITS), which we named 18S rRNA, ITS1, 5.8S rRNA, ITS2 and 28S rRNA. We tested and optimized conditions for cloning these complicated rDNA sequences, including specific rules of primer design, improvements in the reaction system, and selection of the DNA polymerase.

Salinity stress resistance offered by endophytic fungal interaction between Penicillium minioluteum LHL09 and glycine max. L

Endophytic fungi are little known for their role in gibberellins (GAs) synthesis and abiotic stress resistance in crop plants. We isolated 10 endophytes from the roots of field-grown soybean and screened their culture filtrates (CF) on the GAs biosynthesis mutant rice line - Waito-C. CF bioassay showed that endophyte GMH-1B significantly promoted the growth of Waito-C compared with controls. GMH-1B was identified as Penicillium minioluteum LHL09 on the basis of ITS regions rDNA sequence homology and phylogenetic analyses. GC/MS-SIM analysis of CF of P. minioluteum revealed the presence of bioactive GA(4) and GA(7). In endophyte-soybean plant interaction, P. minioluteum association significantly promoted growth characteristics (shoot length, shoot fresh and dry biomasses, chlorophyll content, and leaf area) and nitrogen assimilation, with and without sodium chloride (NaCl)-induced salinity (70 and 140 mM) stress, as compared with control. Field-emission scanning electron microcopy showed active colonization of endophyte with host plants before and after stress treatments. In response to salinity stress, low endogenous abscisic acid and high salicylic acid accumulation in endophyte-associated plants elucidated the stress mitigation by P. minioluteum. The endophytic fungal symbiosis of P. minioluteum also increased the daidzein and genistein contents in the soybean as compared with control plants, under salt stress. Thus, P. minioluteum ameliorated the adverse effects of abiotic salinity stress and rescued soybean plant growth by influencing biosynthesis of the plant's hormones and flavonoids.

[Construction of vector of multiple loci gene targeting in leghorn chicken based on BAC with Cre/lox P system]

Based on the sequence of BAC (Bacterial Artificial Chromosome) along with the Cre/lox P system, the gene-targeting vectors to multiple loci of the repetitive internal transcribed spacers between rDNA genes in Leghorn chicken were constructed. The key material of multiple loci gene targeting in vivo would be obtained. First, the plasmid of pYLSV-TDN with TK, HRDS2, and Neo genes was constructed. The TK-HRDS2-Neo DNA fragment obtained from the plasmid of pYLSV-TDN was digested by Not I/HindIII and inserted into the upstream of the lox P site of BAC plasmid for obtaining the selective vector of BAC-TDN. The expression vector of pYLVS-GID with EGFP, hIFN genes, and HRDS1 was then obtained. The plasmid of BAC-TDN-VS-GID was obtained by cotransformation of the selective vector of BAC-TDN and the expression vector of pYLVS-GID to E. coli NS3529 through the action of Cre/lox P system. The gene-targeting vector of BAC-TDN-GID to multiple loci of the ITS region in Leghorn chicken was obtained by cleaving the sequence of pYLVS with the homing endonuclease of I -Sce I and ligating with the linker of LS. The insertion and the insert direction of DNA fragments were identified by restriction digestion or PCR and sequencing in each clone. The significance of the technique ofgene-targeting vector to multiple loci are shown as follows. First, the targeting loci were increased to 100 - 300. Second, the problems of unstable expression of inserted genes were partially solved. Third, the need for safety against toxicity integration was resolved. Fourth, the forbidden zone of gene integrating on the repetitive DNA sequences was broken through.

Possible role of DNA polymerase beta in protecting human bronchial epithelial cells against cytotoxicity of hydroquinone

OBJECTIVE

To explore the toxicological mechanism of hydroquinone in human bronchial epithelial cells and to investigate whether DNA polymerase beta is involved in protecting cells from damage caused by hydroquinone.

METHODS

DNA polymerase beta knock-down cell line was established via RNA interference as an experimental group. Normal human bronchial epithelial cells and cells transfected with the empty vector of pEGFP-C1 were used as controls. Cells were treated with different concentrations of hydroquinone (ranged from 10 micromol/L to 120 micromol/L) for 4 hours. MTT assay and Comet assay [single-cell gel electrophoresis (SCGE)] were performed respectively to detect the toxicity of hydroquinone.

RESULTS

MTT assay showed that DNA polymerase beta knock-down cells treated with different concentrations of hydroquinone had a lower absorbance value at 490 nm than the control cells in a dose-dependant manner. Comet assay revealed that different concentrations of hydroquinone caused more severe DNA damage in DNA polymerase beta knock-down cell line than in control cells and there was no significant difference in the two control groups.

CONCLUSIONS

Hydroquinone has significant toxicity to human bronchial epithelial cells and causes DNA damage. DNA polymerase beta knock-down cell line appears more sensitive to hydroquinone than the control cells. The results suggest that DNA polymerase beta is involved in protecting cells from damage caused by hydroquinone.

Interaction of mouse Pem protein and cell division cycle 37 homolog

Mouse Pem, a homeobox gene, encodes a protein consisting of 210 amino acid residues. To study the function of mouse Pem protein, we used the yeast two-hybrid system to screen the library of 7-day mouse embryo with full-length mouse Pem cDNA. Fifty-two colonies were obtained after 1.57 x 10(8) colonies were screened by nutrition limitation and beta-galactosidase assay. Seven individual insert fragments were obtained from the library, and three of them were identified, one of which was confirmed to be the cell division cycle 37 (Cdc37) homolog gene by sequencing. The interaction between mouse Pem and Cdc37 homolog was then confirmed by glutathione S-transferase pull-down assay, and the possible interaction model was suggested.

Construction of an effective m1 GS ribozyme targeting HCMV UL97 mRNA segment in vitro

A sequence-specific M1GS ribozyme (M1-T3) was constructed by covalently linking an oligonucleotide (guide sequence,GS) to the 3' terminus of M1 RNA ,the catalytic subunit of RNase P from Escherichia coli. The engineered ribozyme is targeted to the mRNA sequence encoding a protein kinase (UL97) of HCMV and could effectively cleave the mRNA segment in vitro. Further studies about the significance of some structural elements in the M1 GS (e.g. the 3' CCA tail sequence and a bridge sequence between the 3' terminus of M1 RNA and the 5' terminus of the GS) were carried out. The results showed that the bridge sequence of 88 nucleotides in a mutated M1 GS (i.e. M1-T3*) dramatically increased the cleavage activity to the substrate in vitro. Moreover, the 3'CCA tail sequence was confirmed to be a necessary element for the cleavage activity of M1 GS ribozyme. These data we got in the study will help in understanding the interaction between the M1 GS RNA and its substrate,and will markedly facilitate the research of a general gene targeting agent for anti-HCMV applications.

In vitro construction of effective M1GS ribozymes targeting HCMV UL54 RNA segments

Seven sequence-specific ribozymes (M1GS RNAs) derived in vitro from the catalytic RNA subunit of Escherichia coli RNase P and targeting the mRNAs transcribed by the UL54 gene encoding the DNA polymerase of human cytomegalovirus were screened from 11 ribozymes that were designed based on four rules: (1) the NCCA-3' terminal must be unpaired with the substrate; (2) the guide sequence (GS) must be at least 12 nt in length; (3) the eighth nucleotide must be U, counting from the site -1; and (4) around the cleavage site, the sites -1/+1/+2 must be U/G/C or C/G/C. Further investigation of the factors affecting the cleavage effect and the optimal ratio for M1GS/substrate was carried out. It was determined that the optimal ratio for M1GS/substrate was 2:1 and too much M1GS led to substrate degrading. As indicated above, several M1GS that cleaved HCMV UL54 RNA segments in vitro were successfully designed and constructed. Our studies support the use of ribozyme M1GS as antisense molecules to silence HCMV mRNA in vitro, and using the selection procedure as a general approach for the engineering of RNase P ribozymes.

In Vitro Construction of Effective M1GS Ribozymes Targeting HCMV UL54 RNA Segments

Seven sequence-specific ribozymes (M1GS RNAs) derived in vitro from the catalytic RNA subunit of Escherichia coli RNase P and targeting the mRNAs transcribed by the UL54 gene encoding the DNA polymerase of human cytomegalovirus were screened from 11 ribozymes that were designed based on four rules: (1) the NCCA-3′terminal must be unpaired with the substrate; (2) the guide sequence (GS) must be at least 12 nt in length; (3) the eighth nucleotide must be U, counting from the site –1; and (4) around the cleavage site, the sites –1/+1/+2 must be U/G/C or C/G/C. Further investigation of the factors affecting the cleavage effect and the optimal ratio for M1GS/substrate was carried out. It was determined that the optimal ratio for M1GS/substrate was 2:1 and too much M1GS led to substrate degrading. As indicated above, several M1GS that cleaved HCMV UL54 RNA segments in vitro were successfully designed and constructed. Our studies support the use of ribozyme M1GS as antisense molecules to silence HCMV mRNA in vitro, and using the selection procedure as a general approach for the engineering of RNase P ribozymes.

Cloning of Human Myelin Protein Zero-like Genes by Bioinformatics Strategy

To clone novel myelin protein related genes, two human ESTs, which shared significant similarity with the human myelin protein zero gene, were found by the comparison of homologue between the cDNA coding region sequences of MPZ gene and the EST database of NCBI. An 801 bp EST contig was assembled, which was 100% identical with a 128 kb genomic sequence, mapped to 1q24. A 435 bp open reading frame (ORF) within the 801 bp contig was shown by computer analysis. Two primers designed according to the sequence of the contig, were coupled with the primers(lambdagt10-5 and gt10-5) on the sequences flanking cloning site of the cDNA library vector to amplify the cDNA library sequences by nested PCR. New primers, designed based on novel cDNA sequences, were used for the PCR amplification with lambdagt10-5 and gt10-5 in the same way as above. Finally, the human myelin protein zero like gene isoform I and II (MPZL1a, MPZL1b GenBank AF095727, AF092424) were cloned. Comparison of gene and protein structures between MPZL1 and MPZ revealed that MPZL1 is the second member of MPZ family. Mutation analysis of MPZL1 gene was performed in 24 Charcot-Marie-Tooth disease (CMT) families and 26 nonsyndrome deafness families, but no mutation was found.

Identification of a locus for disseminated superficial actinic porokeratosis at chromosome 12q23.2-24.1

Disseminated superficial actinic porokeratosis is an autosomal dominant cutaneous disorder characterized by many uniformly small, minimal, annular, anhidrotic, and keratotic lesions. The genetic basis for this disease is unknown. Using a genomewide search in a large Chinese family, we identified a locus at chromosome 12q23.2-24. 1 responsible for disseminated superficial actinic porokeratosis. The fine mapping study indicates that the disseminated superficial actinic porokeratosis gene is located within a 9.6 cM region between markers D12S1727 and D12S1605, with a maximum two-point LOD score of 20.53 (theta = 0.00) at D12S78. This is the first locus identified for a genetic disease where the major phenotype is porokeratosis. The study provides a map location for isolation of a gene causing disseminated superficial actinic porokeratosis.

Both necrosis and apoptosis contribute to HIV-1-induced killing of CD4 cells

BACKGROUND

Data currently available on HIV-1-induced cytopathology is unclear regarding the mechanism of cell killing.

OBJECTIVE

To clarify the extent to which apoptosis or necrosis is involved in HIV-1-induced cell death in view of conflicting existing data.

METHODS

T lymphoblastoid cells or peripheral blood mononuclear cells were infected by various strains of HIV-1 and the numbers of apoptotic or necrotic cells were quantified at various times after infection using video-image analysis techniques; the results were compared with the amount of fragmented DNA using a quantitative method. Measurement of mitochondrial transmembrane potential (deltapsi(m)) and intracellular calcium concentrations [Ca2+]i was performed with fluorescent probes and fluorescence concentration analysis (FCA).

RESULTS

Although lymphoblastoid and monocytoid cells acutely infected by HIV-1 had increased levels of fragmented DNA, a marker of apoptotic cell death, few (<12%) had condensed chromatin and fragmented nuclei, the morphological features of apoptosis. The predominant alterations in acutely infected cells were distended endoplasmic reticulum and abnormal mitochondria; these ultrastructural changes are consistent with necrosis, although some infected cells simultaneously displayed features of both necrosis and apoptosis. Viability of cells persistently infected by HIV-1 was only minimally reduced from that of uninfected cells. This reduction was accounted for by an increased propensity of the persistently infected cells to die by apoptosis. Alterations in [Ca2+]i and deltapsi(m) occurred in both acutely and persistently infected cells.

CONCLUSION

Both necrosis and apoptosis contribute to HIV-1-induced killing of CD4 cells.

Reovirus variants selected during persistent infections of L cells contain mutations in the viral S1 and S4 genes and are altered in viral disassembly

Reoviruses isolated from persistently infected cultures (PI viruses) can grow in the presence of ammonium chloride, a weak base that blocks acid-dependent proteolysis of viral outer-capsid proteins during viral entry into cells. We used reassortant viruses isolated from crosses of wild-type (wt) reovirus strain, type 1 Lang, and three independent PI viruses, L/C, PI 2A1, and PI 3-1, to identify viral genes that segregate with the capacity of PI viruses to grow in cells treated with ammonium chloride. Growth of reassortant viruses in ammonium chloride-treated cells segregated with the S1 gene of L/C and the S4 gene of PI 2A1 and PI 3-1. The S1 gene encodes viral attachment protein sigma1, and the S4 gene encodes outer-capsid protein sigma3. To identify mutations in sigma3 selected during persistent reovirus infection, we determined the S4 gene nucleotide sequences of L/C, PI 2A1, PI 3-1, and four additional PI viruses. The deduced amino acid sequences of sigma3 protein of six of these PI viruses contained a tyrosine-to-histidine substitution at residue 354. To determine whether mutations selected during persistent infection alter cleavage of the viral outer capsid, the fate of viral structural proteins was assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after treatment of virions of wt and PI viruses with chymotrypsin in vitro. Proteolysis of PI virus outer-capsid proteins sigma3 and mu1C occurred with faster kinetics than proteolysis of wt virus outer-capsid proteins. These results demonstrate that mutations in either the S1 or S4 gene alter acid-dependent disassembly of the reovirus outer capsid and suggest that increased efficiency of proteolysis of viral outer-capsid proteins is important for maintenance of persistent reovirus infections of cultured cells.

Anergy and apoptosis in CD8+ T cells from HIV-infected persons

CD8+T cells from HIV-infected persons increase early in infection, display increased levels of activation Ags, and abnormal MHC-restricted, HIV-specific and nonspecific cytotoxicity abilities. Paradoxically, these cells are also unresponsive to T cell signaling in vitro and have decreased in vitro cloning potential. HIV-specific CTL precursors also are lost late in infection. A quantitative Southern blotting technique showed that CD8+ T cells from asymptomatic, HIV-infected persons have increased DNA fragmentation after overnight incubation. DNA fragmentation was reduced by an endonuclease inhibitor but not by cycloheximide, suggesting that a pre-apoptotic state exists in vivo. Partial inhibition of DNA fragmentation also could be induced by IL-2 addition. No consistent difference in fragmentation was observed among CD8+ subpopulations from HIV-infected individuals, although only CD8+ T cells that did not express activation Ags (DR-, CD28+, CD57- phenotype) showed reduced fragmentation when incubated in IL-2. A dramatic increase in CD8+, CD28- cells was observed in asymptomatic HIV-infected people. A subset of CD8+, CD28- cells in both controls and HIV-infected people do not proliferate to T cell signals, and these cells from controls demonstrate increased DNA fragmentation in vitro after 3 days of incubation, regardless of stimulation conditions. This suggests that the cells are end-stage cells. Taken together, the data suggest an increase in anergic or apoptotic CD8+ T cells in HIV-infected persons. Eventual depletion of HIV-specific CD8+ T cells may occur through a process of proliferation, anergy induction, and apoptosis.

Anergy and apoptosis in CD8+ T cells from HIV-infected persons

CD8+T cells from HIV-infected persons increase early in infection, display increased levels of activation Ags, and abnormal MHC-restricted, HIV-specific and nonspecific cytotoxicity abilities. Paradoxically, these cells are also unresponsive to T cell signaling in vitro and have decreased in vitro cloning potential. HIV-specific CTL precursors also are lost late in infection. A quantitative Southern blotting technique showed that CD8+ T cells from asymptomatic, HIV-infected persons have increased DNA fragmentation after overnight incubation. DNA fragmentation was reduced by an endonuclease inhibitor but not by cycloheximide, suggesting that a pre-apoptotic state exists in vivo. Partial inhibition of DNA fragmentation also could be induced by IL-2 addition. No consistent difference in fragmentation was observed among CD8+ subpopulations from HIV-infected individuals, although only CD8+ T cells that did not express activation Ags (DR-, CD28+, CD57- phenotype) showed reduced fragmentation when incubated in IL-2. A dramatic increase in CD8+, CD28- cells was observed in asymptomatic HIV-infected people. A subset of CD8+, CD28- cells in both controls and HIV-infected people do not proliferate to T cell signals, and these cells from controls demonstrate increased DNA fragmentation in vitro after 3 days of incubation, regardless of stimulation conditions. This suggests that the cells are end-stage cells. Taken together, the data suggest an increase in anergic or apoptotic CD8+ T cells in HIV-infected persons. Eventual depletion of HIV-specific CD8+ T cells may occur through a process of proliferation, anergy induction, and apoptosis.

Simultaneous determinations by theophylline and its major metabolites in urine by reversed-phase ion-pair high-performance liquid chromatography

A new, highly slective high-performance liquid-chromatographic (HPLC) assay for theophylline and its major metabolites in urine is described. The method utilizes an ion-pair extraction followed by separation and quantitation by reversed-phase ion-pair gradient-elution HPLC. Comparison with several other methods showed that interferences were present in too many blank urine samples to allow for the accurate quantitation of the metabolites of theophylline by direct injection--isocratic HPLC assays. Sample processing involving ion-pair complexing and extraction together with gradient-elution systems is recommended for accurate pharmacokinetic studies.