A quantitative basis for antiretroviral therapy for HIV-1 infection

Highly active antiretroviral therapy (HAART) has dramatically decreased mortality from HIV-1 infection and is a major achievement of modern medicine. However, there is no fundamental theory of HAART. Elegant models describe the dynamics of viral replication, but a metric for the antiviral activity of drug combinations relative to a target value needed for control of replication is lacking. Treatment guidelines are based on empirical results of clinical trials in which other factors such as regimen tolerability also affect outcome. Why only certain drug combinations control viral replication remains unclear. Here we quantify the intrinsic antiviral activity of antiretroviral drug combinations. We show that most single antiretroviral drugs show previously unappreciated complex nonlinear pharmacodynamics that determine their inhibitory potential at clinical concentrations. We demonstrate that neither of the major theories for drug combinations accurately predicts the combined effects of multiple antiretrovirals. However, the combined effects can be understood with a new approach that considers the degree of independence of drug effects. This analysis allows a direct comparison of the inhibitory potential of different drug combinations under clinical concentrations, reconciles the results of clinical trials, defines a target level of inhibition associated with treatment success and provides a rational basis for treatment simplification and optimization.     

LMI1-like and KNOX1 genes coordinately regulate plant leaf development in dicotyledons

Plant Molecular Biology - This report reveals that the LMI1-like and KNOX1 genes coordinately control the leaf development and different combinations of those genes which produce diverse leaf...     

Linkage of the Dao-1 gene for D-amino-acid oxidase to the pgm-1 gene for phosphoglucomutase-1 on the mouse chromosome 5

Linkage of the Dao-1 gene controlling D-amino-acid oxidase to the Pgm-1 gene controlling phosphoglucomutase-1 on the mouse chromosome 5 was examined. Mutant ddY/DAO- mice carrying a null Dao-1c allele had a Pgm-1a allele. Mutant mice were crossed to C3H/HeN and NZB/Kl mice carrying the Dao-1+ and Pgm-1b alleles. The hybrid F1 mice were backcrossed to the ddY/DAO- and their progeny were examined for alleles for D-amino-acid oxidase and phosphoglucomutase-1. In both backcrosses, the progeny with recombinant-type combinations of the alleles were significantly less than the progeny with the parental-type combinations, indicating the linkage of the Dao-1 and Pgm-1 genes. The recombination frequency between these loci was estimated to be 19.8 +/- 4.0%.     

THE F1 HYBRIDS OF SOME SAPOGENIN-BEARING DIOSCOREA SPECIES

Fifteen species of Dioscorea and one of Rajania were cross-pollinated in 60 different combinations. Crosses among New World species were partially successful, whereas crosses between New and Old World or among Old World species usually failed entirely. Viable hybrids were obtained from 13 combinations, including all 12 possible combinations among 4 sapogenin-bearing species. Hybrids were intermediate to their parents with respect to vegetative characteristics, but exhibited wider variation or poor physiological control of critical growth phases, including length of the juvenile phase, dry season dormancy, and season of flowering. The flowers of hybrids were also intermediate to those of parents with no clear expressions of dominance. Chromosomal behavior of hybrids was essentially normal but reduction in fertility was manifested by high percentages of abnormal pollen, low crossability and poor seed germination. The significance of these findings with reference to speciation, reproductive barriers, and improvement by breeding is discussed.     

Optimal Combinations of Broadly Neutralizing Antibodies for Prevention and Treatment of HIV-1 Clade C Infection

The identification of a new generation of potent broadly neutralizing HIV-1 antibodies (bnAbs) has generated substantial interest in their potential use for the prevention and/or treatment of HIV-1 infection. While combinations of bnAbs targeting distinct epitopes on the viral envelope (Env) will likely be required to overcome the extraordinary diversity of HIV-1, a key outstanding question is which bnAbs, and how many, will be needed to achieve optimal clinical benefit. We assessed the neutralizing activity of 15 bnAbs targeting four distinct epitopes of Env, including the CD4-binding site (CD4bs), the V1/V2-glycan region, the V3-glycan region, and the gp41 membrane proximal external region (MPER), against a panel of 200 acute/early clade C HIV-1 Env pseudoviruses. A mathematical model was developed that predicted neutralization by a subset of experimentally evaluated bnAb combinations with high accuracy. Using this model, we performed a comprehensive and systematic comparison of the predicted neutralizing activity of over 1,600 possible double, triple, and quadruple bnAb combinations. The most promising bnAb combinations were identified based not only on breadth and potency of neutralization, but also other relevant measures, such as the extent of complete neutralization and instantaneous inhibitory potential (IIP). By this set of criteria, triple and quadruple combinations of bnAbs were identified that were significantly more effective than the best double combinations, and further improved the probability of having multiple bnAbs simultaneously active against a given virus, a requirement that may be critical for countering escape in vivo. These results provide a rationale for advancing bnAb combinations with the best in vitro predictors of success into clinical trials for both the prevention and treatment of HIV-1 infection.     

Polymorphisms in glutathione S-transferase M1 and T1 (GSTM1 and GSTT1) in the indigenous and the nonresident population of the Kemerovo region

GSTM1 and GSTT1 gene polymorphisms were studied in Shorians, Teleuts, and Caucasians of the Kemerovo region. It has been shown that distribution of homozygous deletions in the examined groups is significantly heterogeneous. The frequency of deletion genotypes and combinations of deletion in these genes was lower in Shorians and, Teleuts than in Caucasians.     

Insulin-like growth factor-1 receptor and ErbB kinase inhibitor combinations block proliferation and induce apoptosis through cyclin D1 reduction and Bax activation

The insulin-like growth factor-1 receptor (IGF-1R) and ErbB family of receptors are receptor tyrosine kinases that play important roles in cancer. Lack of response and resistance to therapies targeting ErbB receptors occur and are often associated with activation of the IGF-1R pathway. Combinations of agents that inhibit IGF-1R and ErbB receptors have been shown to synergistically block cancer cell proliferation and xenograft tumor growth. To determine the mechanism by which targeting both IGF-1R and ErbB receptors causes synergistic effects on cell growth and survival, we investigated the effects of combinations of selective IGF-1R and ErbB kinase inhibitors on proliferative and apoptotic signaling. We identified A431 squamous cell carcinoma cells as most sensitive to combinations of ErbB and IGF-1R inhibitors. The inhibitor combinations resulted in not only blockade of A431 cell proliferation, but also induced apoptosis, which was not seen with either agent alone. Upon examining phosphorylation states and expression levels of proteins in the IGF-1R and ErbB signaling pathways, we found a correlation between the ability of combinations to inhibit proliferation and to decrease levels of phosphorylated Akt and cyclin D1. In addition, the massive cell death induced by combined IGF-1R/ErbB inhibition was associated with Mcl-1 reduction and Bax activation. Thus, targeting both IGF-1R and ErbB receptors simultaneously results in cell cycle arrest and apoptosis through combined effects on Akt, cyclin D1, and Bax activation.     

Inheritance of the serotonin level in 1st-generation mice from crosses with different inbred strains

The level of serotonin content in brain stem and stomach was studied in the first generation of different combinations of inbred mice strains. The serotonin level was shown in these tissues to be inherited differently. Heterosis was observed in the gastro-intestinal tract. Serotonin brain level depends on strain combinations in crosses.     

Recognition of dileucine-based sorting signals from HIV-1 Nef and LIMP-II by the AP-1 gamma-sigma1 and AP-3 delta-sigma3 hemicomplexes

The sorting of transmembrane proteins to endosomes and lysosomes is mediated by signals present in the cytosolic tails of the proteins. A subset of these signals conform to the [DE]XXXL[LI] consensus motif and mediate sorting via interactions with heterotetrameric adaptor protein (AP) complexes. However, the identity of the AP subunits that recognize these signals remains controversial. We have used a yeast three-hybrid assay to demonstrate that [DE]XXXL[LI]-type signals from the human immunodeficiency virus negative factor protein and the lysosomal integral membrane protein II interact with combinations of the gamma and sigma1 subunits of AP-1 and the delta and sigma3 subunits of AP-3, but not the analogous combinations of AP-2 and AP-4 subunits. The sequence requirements for these interactions are similar to those for binding to the whole AP complexes in vitro and for function of the signals in vivo. These observations reveal a novel mode of recognition of sorting signals involving the gamma/delta and sigma subunits of AP-1 and AP-3.     

甜菊不同杂交组合结实率及其F1代萌发和生长及对NaCl耐性的比较

以甜菊(Stevia rebaudiana Bertoni)的耐盐性较强品种‘中山3号’和‘守田2号’及R-A高含量品种‘中山4号’和‘守田3号’为亲本配置7个杂交组合并获得杂交种子,对种子结实率和发芽率及F1代幼苗的存活率进行统计分析,在此基础上采用砂培和水培方法比较了亲本及F1代扦插苗对NaCl胁迫的耐性.结果表明:品种间杂交组合的结实率均显著高于同系列品种间杂交及自交组合,其中‘守田2号’ב中山3号’杂交组合的结实率最高,为74.9％;7个杂交组合F1代的种子发芽率为63.8％ ～ 89.0％,差异明显;‘守田2号’ב中山4号’杂交组合F1代幼苗存活率相对较低(79.80％),其他杂交组合F1代幼苗存活率均在93％以上.砂培条件下,用100 mmol·L-1NaCl胁迫7d,各杂交组合F1代扦插苗的存活率差异不显著;随NaCl胁迫时间的延长各杂交组合F1代扦插苗的存活率均明显下降;胁迫28 d,‘守田2号’ב守田 3号’杂交组合以及‘中山3号’自交组合F1代扦插苗的存活率显著高于其他杂交组合.水培条件下,用100、150、200和250 mmol·L-1 NaCl胁迫14 d,‘守田2号’ב中山3号’、‘中山3号’ב守田2号’和‘中山3号’ב守田3号’3个杂交组合F1代扦插苗的存活率均显著高于其耐盐亲本及其他杂交组合.研究结果说明:通过杂交提高甜菊耐盐能力是可行的,而亲本的耐盐能力及亲本配置对杂交后代目标性状有较大影响;‘中山3号’ב守田2号’、‘守田2号’ב中山3号’和‘中山3号’ב守田3号’是耐盐性较强的甜菊优良杂交组合.     

Polymorphisms in glutathione S-transferase M1 and T1 (GSTM1 and GSTT1) genes in the indigenous and the nonresident population of the Kemerovo region

GSTM1 and GSTT1 gene polymorphisms were studied in Shorians, Teleuts, and Caucasians of the Kemerovo region. It has been shown that distribution of homozygous deletions in the examined groups is significantly heterogeneous. The frequency of deletion genotypes and combinations of deletion in these genes was lower in Shorians and, Teleuts than in Caucasians.     

Pyrosequence-based typing of alleles of the HLA-DQB1 gene

DNA typing of alleles of the highly polymorphic HLA-DQBI gene was performed by Pyrosequencing using purified DNA from the 11th International Histocompatibility Workshop human cell lines and samples from the Children's Hospital of Pittsburgh registry of diabetics and their first-degree relatives. Pyrosequencing was optimized for genotyping exon 2 of the HLA-DQB1 gene, but the procedure should be applicable to other HLA loci. The 47 HLA-DQB1 alleles were readily identifiable, as were the 1,128 potential allelic heterozygous combinations. The method required PCR conditions that specifically amplified DQB1 but not the pseudogene, DQB2. The new method of pyrosequence-based typing can be performed in 96- or 384-well format. The 61 polymorphic residues of DQB1 exon 2 were identified within four pyrosequencing reactions, obtained by a 70-nucleotide read length in each reaction, in about an hour's time. Allelic combinations of HLA-DQB1 most frequentlyfound in the population of diabetics and their immediate family members were analyzed and successfully compared to typing of the DQB1 alleles by sequence-specific oligonucleotide probe protocols. Pyrosequence-based typing is compatible with genotyping of allelic combinations expected from heterozygous individuals, resulting in nucleotide resolution of the highly polymorphic HLA system. Using pyrosequencing, more than 750 sample wells can be processed in a working day, resulting in the identification of more than 50,000 bases.     

Polymorphism of the theta1 and mu1 glutathione s-transferase genes (GSTT1, GSTM1) in patients with atopic bronchial asthma from the West Siberian region

Polymorphism for the GSTT1 and GSTM1 null alleles was analyzed in 69 patients with atopic bronchial asthma (BA) and in 57 healthy individuals from Tomsk. The two samples did not differ in frequencies of genotypes 0/0 and + of either gene or in frequencies of genotype combinations. No association was observed for GST and BA severity. Thus, the GST null alleles proved to be unimportant for BA.     

SEXUAL REPRODUCTION AND INTERCROSSING IN VOLVULINA STEINW1

Gametes of Volvulina steinii bear near-apical mating papillae. Zygospore germination yields a single biflagellate cell that develops into a colony xuhose asexual progeny are all of the same mating type. Backcrossing of clones of progeny indicated a 1 :1 ratio of mating types among the progeny. Of 20 clones from a number of localities, none was homothallic and 3 showed no matins: reaction. Mating reactions of clones crossed in all possible combinations indicated the presence of 2 sexually isolated groups of clones producing smooth-walled zygospores and 1 group that produced spiny-walled zygospores. In the latter group weak and nonreciprocal mating reactions occurred in some clone combinations. Failure of germination of spiny-walled zygospores from certain crosses suggests further subdivision into genetically isolated groups.     

Antagonism between Cry1Ac1 and Cyt1A1 toxins of bacillus thuringiensis

Most strains of the insecticidal bacterium Bacillus thuringiensis have a combination of different protoxins in their parasporal crystals. Some of the combinations clearly interact synergistically, like the toxins present in B. thuringiensis subsp. israelensis. In this paper we describe a novel joint activity of toxins from different strains of B. thuringiensis. In vitro bioassays in which we used pure, trypsin-activated Cry1Ac1 proteins from B. thuringiensis subsp. kurstaki, Cyt1A1 from B. thuringiensis subsp. israelensis, and Trichoplusia ni BTI-Tn5B1-4 cells revealed contrasting susceptibility characteristics. The 50% lethal concentrations (LC50s) were estimated to be 4,967 of Cry1Ac1 per ml of medium and 11.69 ng of Cyt1A1 per ml of medium. When mixtures of these toxins in different proportions were assayed, eight different LC50s were obtained. All of these LC50s were significantly higher than the expected LC50s of the mixtures. In addition, a series of bioassays were performed with late first-instar larvae of the cabbage looper and pure Cry1Ac1 and Cyt1A1 crystals, as well as two different combinations of the two toxins. The estimated mean LC50 of Cry1Ac1 was 2.46 ng/cm2 of diet, while Cyt1A1 crystals exhibited no toxicity, even at very high concentrations. The estimated mean LC50s of Cry1Ac1 crystals were 15.69 and 19.05 ng per cm2 of diet when these crystals were mixed with 100 and 1,000 ng of Cyt1A1 crystals per cm2 of diet, respectively. These results indicate that there is clear antagonism between the two toxins both in vitro and in vivo. Other joint-action analyses corroborated these results. Although this is the second report of antagonism between B. thuringiensis toxins, our evidence is the first evidence of antagonism between toxins from different subspecies of B. thuringiensis (B. thuringiensis subsp. kurstaki and B. thuringiensis subsp. israelensis) detected both in vivo and in vitro. Some possible explanations for this relationship are discussed.     

emb-1 encodes the APC16 subunit of the Caenorhabditis elegans anaphase-promoting complex

In the nematode Caenorhabditis elegans, temperature-sensitive mutants of emb-1 arrest as one-cell embryos in metaphase of meiosis I in a manner that is indistinguishable from embryos that have been depleted of known subunits of the anaphase-promoting complex or cyclosome (APC/C). Here we show that the emb-1 phenotype is enhanced in double mutant combinations with known APC/C subunits and suppressed in double mutant combinations with known APC/C suppressors. In addition to its meiotic function, emb-1 is required for mitotic proliferation of the germline. These studies reveal that emb-1 encodes K10D2.4, a homolog of the small, recently discovered APC/C subunit, APC16.     

Canine Mhc DRB1 genotyping by PCR–RFLP analysis

A polymerase chain reaction (PCR) genotyping procedure has been developed for the canine major histocompatibility complex DRB1 gene ( Cafa-DRB1 ), which allows us to distinguish all the DRB1 alleles described to date and reveals the existence of new ones. The polymorphic second exon of the Cafa-DRB1 gene was amplified and the product analysed for restriction fragment length polymorphism (RFLP) with the enzymes Rsa I, Mbo I, Taq I and Asp HI. Nine RFLP combinations could be associated with previously known alleles. Two new RFLP combinations corresponded to new alleles and were confirmed by DNA sequencing ( Cafa-DRB1 *10 and Cafa-DRB1 *11). Close associations between RFLPs in the DRB1 second exon and the presence of specific amino acid residues included in the side-chain pockets of the antigen-binding site of the DR molecule are also described.     

Polymorphism of glutathione S-transferase genes M1 and T1 in patients with motor neuron disease from the city of Moscow

Comparison of the frequency distributions of alleles, genotypes, and genotype combinations of genes GSTM1 and GSTT1 did not show statistically significant differences between patients with motor neuron disease (MND) and a random sample from the Moscow population. Apparently, these genes are not involved in MND pathogenesis in these patients.     

13/17罗伯逊易位猪POU1F1基因多态性

采用外周血淋巴细胞培养制备染色体标本, 对13/17罗伯逊易位猪的3种杂交组合的394头后代进行核型分析, 出现3种核型猪：13/17易位纯合子猪[2n=36, XY或XX, rob(13;17)]、13/17易位杂合子猪[2n=37, XY或XX, rob(13;17)]和正常核型猪[2n=38, XY或XX]。应用PCR-RFLP技术在POU1F1基因的1 746 bp扩增片段中检测到1个RsaⅠ限制性内切酶的多态位点。应用PCR-SSCP技术检测POU1F1基因第4外显子, 在3种杂交后代群中均未检测到突变。遗传多态性分析结果表明：RsaⅠ酶切多态位点的突变在3种杂交后代群中A等位基因和AA基因型频率占优势, 在3种核型群体中也是A等位基因和AA基因型频率占优势, 其中AB基因型频率在易位杂合型群体中较高。各杂交后代群均未达到Hardy-Weinberg平衡, 不同核型群亦处于非平衡状态。13/17易位杂合子猪×13/17易位杂合子猪和13/17易位杂合子猪×约克两杂交后代群的PIC表现为中度多态, 而13/17易位杂合子猪×皮杜杂交后代群表现为低度多态; 易位杂合型群体表现为中度多态, 正常核型和易位纯合型群体表现低度多态性。