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At least 721 records · Page 40Linked to original sources
PubMed2002

A conserved Drosophila transportin-serine/arginine-rich (SR) protein permits nuclear import of Drosophila SR protein splicing factors and their antagonist repressor splicing factor 1.

Members of the highly conserved serine/arginine-rich (SR) protein family are nuclear factors involved in splicing of metazoan mRNA precursors. In mammals, two nuclear import receptors, transportin (TRN)-SR1 and TRN-SR2, are responsible for targeting SR proteins to the nucleus. Distinctive features in the nuclear localization signal between Drosophila and mammalian SR proteins prompted us to examine the mechanism by which Drosophila SR proteins and their antagonist repressor splicing factor 1 (RSF1) are imported into nucleus. Herein, we report the identification and characterization of a Drosophila importin beta-family protein (dTRN-SR), homologous to TRN-SR2, that specifically interacts with both SR proteins and RSF1. dTRN-SR has a broad localization in the cytoplasm and the nucleus, whereas an N-terminal deletion mutant colocalizes with SR proteins in nuclear speckles. Far Western experiments established that the RS domain of SR proteins and the GRS domain of RSF1 are required for the direct interaction with dTRN-SR, an interaction that can be modulated by phosphorylation. Using the yeast model system in which nuclear import of Drosophila SR proteins and RSF1 is impaired, we demonstrate that complementation with dTRN-SR is sufficient to target these proteins to the nucleus. Together, the results imply that the mechanism by which SR proteins are imported to the nucleus is conserved between Drosophila and humans.

Active Transport, Cell Nucleus↗
PubMed2005

Chemotherapy permits resection of metastatic colorectal cancer: experience from Intergroup N9741.

BACKGROUND: Fluorouracil (5-FU), oxaliplatin and irinotecan combinations improve time to tumor progression (TTP), objective response and overall survival (OS) in patients with metastatic colorectal cancer (MCRC). Here we identify and describe patients treated on Intergroup study N9741 who initially had inoperable MCRC, but who obtained sufficient chemotherapeutic benefit to allow removal of their metastatic disease. PATIENTS AND METHODS: Patient research records in study arms (A) irinotecan/5-FU/leucovorin (LV) (IFL, n = 264), (F) oxaliplatin/5-FU/LV (FOLFOX4, n = 267) and (G) oxaliplatin/irinotecan (IROX, n = 265) were reviewed. TTP and median OS were calculated. RESULTS: Twenty-four (3.3%) of 795 randomized patients underwent curative metastatic disease resection [hepatectomy, 16; radiofrequency-ablation (RFA), six; lung resection, two]. Twenty-two out of 24 (92%) resected patients received an oxaliplatin-based regimen (FOLFOX4, 11; IROX, 11). Seven patients (29.2%) remain disease-free; relapses occurred mainly in the resected organ. Median OS in resected patients is 42.4 months, and median TTP is 18.4 months. All six patients treated with RFA have recurred. Four out of five (80%) patients who received chemotherapy following resection are disease-free. CONCLUSIONS: Resection of metastatic disease after chemotherapy is possible in a small but important subset of patients with MCRC, particularly after receiving an oxaliplatin-based chemotherapy regimen, with encouraging OS and TTP observed in these highly selected patients.

Adult↗
PubMed2007

A novel method of supplying nutrients permits predictable shoot growth and root : shoot ratios of pre-transplant bedding plants.

BACKGROUND AND AIMS: Growth of bedding plants, in small peat plugs, relies on nutrients in the irrigation solution. The object of the study was to find a way of modifying the nutrient supply so that good-quality seedlings can be grown rapidly and yet have the high root : shoot ratios essential for efficient transplanting. METHODS: A new procedure was devised in which the concentrations of nutrients in the irrigation solution were modified during growth according to changing plant demand, instead of maintaining the same concentrations throughout growth. The new procedure depends on published algorithms for the dependence of growth rate and optimal plant nutrient concentrations on shoot dry weight W(s) (g m(-2)), and on measuring evapotranspiration rates and shoot dry weights at weekly intervals. Pansy, Viola tricola 'Universal plus yellow' and petunia, Petunia hybrida 'Multiflora light salmon vein' were grown in four independent experiments with the expected optimum nutrient concentration and fractions of the optimum. Root and shoot weights were measured during growth. KEY RESULTS: For each level of nutrient supply W(s) increased with time (t) in days, according to the equation DeltaW(s)/Deltat=K(2)W(s)/(100+W(s)) in which the growth rate coefficient (K(2)) remained approximately constant throughout growth. The value of K(2) for the optimum treatment was defined by incoming radiation and temperature. The value of K(2) for each sub-optimum treatment relative to that for the optimum treatment was logarithmically related to the sub-optimal nutrient supply. Provided the aerial environment was optimal, R(sb)/R(o) approximately W(o)/W(sb) where R is the root : shoot ratio, W is the shoot dry weight, and sb and o indicate sub-optimum and optimum nutrient supplies, respectively. Sub-optimal nutrient concentrations also depressed shoot growth without appreciably affecting root growth when the aerial environment was non-limiting. CONCLUSION: The new procedure can predict the effects of nutrient supply, incoming radiation and temperature on the time course of shoot growth and the root : shoot ratio for a range of growing conditions.

Environment↗
PubMed2006

Cyclin-dependent kinase 5 permits efficient cytoskeletal remodeling--a hypothesis on neuronal migration.

Migration of neurons to their proper position underlies mammalian brain development. To remain on the proper path, a migrating neuron needs to detect various external signals and respond by efficiently remodeling its cytoskeleton. Cyclin-dependent kinase 5 (Cdk5), a member of the cyclin-dependent kinase family, regulates neuronal migration by phosphorylating a number of intracellular substrates. Deficiencies in Cdk5 preferentially cause impairments in radial glia-guided migration, a process that involves complex remodeling of the cytoskeleton, particularly the microtubules. Furthermore, the defined substrates of Cdk5 that are important for migration generally link Cdk5 to the cytoskeleton. Interestingly, none of these phosphorylation events seem to directly control the activity of the substrates. Taken together, these findings support a model in which Cdk5 does not directly control the detection of any specific external signals but instead regulates efficient remodeling of the cytoskeleton through phosphorylation of multiple substrates.

Aging↗
PubMed1994

Ketamine-xylazine anaesthesia permits a KATP channel antagonist to attenuate preconditioning in rabbit myocardium.

OBJECTIVE: ATP sensitive potassium (KATP) channels have been implicated in the mechanism of ischaemic preconditioning, though apparently not in the pentobarbitone anaesthetised rabbit model. The aim of this study was to test whether potassium channel activation and blockade would alter protection in ketamine-xylazine anaesthetised rabbits. METHODS: In situ rabbit hearts (n = 50) received 30 min regional ischaemia and 3 h reperfusion. Some hearts were preconditioned by 5 min regional ischaemia and 10 min reperfusion prior to the long ischaemia. Infarct size was determined by tetrazolium staining. RESULTS: In rabbits anaesthetised with ketamine-xylazine, brief preconditioning ischaemia continued to produce much smaller infarcts than in non-preconditioned animals [19(SEM 2)% v 47(3)%, p < or = 0.05]. blocking KATP channels by pretreating with glibenclamide resulted in 35(3)% infarction in non-preconditioned hearts and aborted protection in preconditioned hearts [35(4)% infarction]. Substituting the potassium channel activator pinacidil for the short ischaemia caused comparable reductions in infarct size [28(4)%, p < or = 0.05 v non-preconditioned hearts]. This protection, however, could be blocked by concomitant administration of the adenosine receptor blocker 8-(p-sulphophenyl)theophylline (SPT) [44(3)% infarction]. CONCLUSIONS: When ketamine-xylazine anaesthesia was employed, the protective effects of ischaemic preconditioning in the rabbit heart could be blocked by glibenclamide, and pinacidil could mimic the protection of ischaemic preconditioning. Because the protection afforded by pinacidil could be blocked by SPT, however, there is still some question whether the KATP channel is the end effector of preconditioning.

Animals↗
PubMed2006

Heart-type fatty acid-binding protein permits early risk stratification of pulmonary embolism.

AIMS: We investigated the value of a novel early biomarker, heart-type fatty acid-binding protein (H-FABP), in risk stratification of patients with acute pulmonary embolism (PE). METHODS AND RESULTS: We prospectively included 107 consecutive patients with confirmed PE. The endpoints were (i) PE-related death or major complications and (ii) overall 30-day mortality. Overall, 29 patients (27%) had abnormal (>6 ng/mL) H-FABP levels at presentation. Of those, 12 (41%) had a complicated course, whereas all patients with normal baseline H-FABP had a favourable 30-day outcome (OR, 71.45; P<0.0001). At multivariable analysis, H-FABP (P<0.0001), but not cardiac troponin T (P=0.13) or N-terminal pro-brain natriuretic peptide (P=0.36), predicted an adverse outcome. Evaluation of a strategy combining biomarker testing with echocardiography revealed that patients with a negative H-FABP test had an excellent prognosis regardless of echocardiographic findings. In contrast, patients with a positive H-FABP test had a complication rate of 23.1% even in the presence of a normal echocardiogram, and this rose to 57.1% if echocardiography also demonstrated right ventricular dysfunction (OR vs. a negative H-FABP test, 5.6 and 81.4, respectively). CONCLUSION: H-FABP is a promising early indicator of right ventricular injury and dysfunction in acute PE. It may help optimize risk stratification algorithms and treatment strategies.

Biomarkers↗
PubMed1984

The genetic analysis of a chromosome-specific meiotic mutant that permits a premature separation of sister chromatids in Drosophila melanogaster.

mei- G87 is a recessive meiotic mutant that increases second chromosome nondisjunction in both males and females. A significant proportion of the diplo -2 exceptions are equational . In females, diplo -2 reductional exceptions are usually noncrossovers , but, in equational exceptions, crossover frequency and distribution are the same as that found in the haplo-2 controls. The frequencies of nondisjunction are relatively low: 0.6% in females and 1.3% in males. Nondisjunction frequency is affected by environmental conditions (possibly humidity). The defect in mei- G87 , as in other "second division" mutants, appears to be a failure to maintain sister-chromatid cohesion. mei- G87 increases nondisjunction of only the second chromosome. This may indicate either a weak mutant with only the second chromosome being sensitive enough to misbehave or it may indicate that chromosome-specific regions responsible for sister-chromatid cohesion exist.

Animals↗
PubMed1998

Tip loci: six Chlamydomonas nuclear suppressors that permit the translocation of proteins with mutant thylakoid signal sequences.

Mutations within the signal sequence of cytochrome f (cytf) in Chlamydomonas inhibit thylakoid membrane protein translocation and render cells nonphotosynthetic. Twenty-seven suppressors of the mutant signal sequences were selected for their ability to restore photoautotrophic growth and these describe six nuclear loci named tip1 through 6 for thylakoid insertion protein. The tip mutations restore the translocation of cytf and are not allele specific, as they suppress a number of different cytf signal sequence mutations. Tip5 and 2 may act early in cytf translocation, while Tip1, 3, 4, and 6 are engaged later. The tip mutations have no phenotype in the absence of a signal sequence mutation and there is genetic interaction between tip4, and tip5 suggesting an interaction of their encoded proteins. As there is overlap in the energetic, biochemical and genetic requirements for the translocation of nuclear and chloroplast-encoded thylakoid proteins, the tip mutations likely identify components of a general thylakoid protein translocation apparatus.

Animals↗
PubMed1999

Temporal and multiple quantitative trait loci analyses of resistance to bacterial wilt in tomato permit the resolution of linked loci.

Ralstonia solanacearum is a soil-borne bacterium that causes the serious disease known as bacterial wilt in many plant species. In tomato, several QTL controlling resistance have been found, but in different studies, markers spanning a large region of chromosome 6 showed strong association with the resistance. By using two different approaches to analyze the data from a field test F3 population, we show that at least two separate loci approximately 30 cM apart on this chromosome are most likely involved in the resistance. First, a temporal analysis of the progression of symptoms reveals a distal locus early in the development of the disease. As the disease progresses, the maximum LOD peak observed shifts toward the proximal end of the chromosome, obscuring the distal locus. Second, although classical interval mapping could only detect the presence of one locus, a statistical "two-QTL model" test, specifically adapted for the resolution of linked QTL, strongly supported the hypothesis for the presence of two loci. These results are discussed in the context of current molecular knowledge about disease resistance genes on chromosome 6 and observations made by tomato breeders during the production of bacterial wilt-resistant varieties.

Bacterial Infections↗
PubMed1993

A single polymorphic STR system in the human phenylalanine hydroxylase gene permits rapid prenatal diagnosis and carrier screening for phenylketonuria.

Phenylketonuria (PKU) is an autosomal recessive genetic disorder caused by phenylalanine hydroxylase (PAH) deficiency. Individuals afflicted with PKU develop irreversible mental retardation that can be largely prevented by the administration of a low-phenylalanine diet. A number of restriction fragment-length polymorphisms (RFLPs) have been identified in the PAH gene. Combinations of RFLPs constitute unique haplotypes that can be used to identify mutant PAH chromosomes for prenatal diagnostic purpose in PKU families. Unfortunately, the utility of haplotype analysis is limited in populations with a single predominant haplotype. We have identified a novel short tandem repeat (STR) within the PAH gene that has an average level of heterozygosity of about 75% in Orientals and about 80% in European Caucasian populations. This single marker is as informative as haplotype analysis in Europeans and nearly twice as informative as haplotype analysis in Orientals. Although there is statistically significant disequilibrium between STR alleles and RFLP-based haplotypes, there is a relatively low degree of disequilibrium between STR alleles and certain RFLP sites. Nevertheless, the combined use of the STR and RFLP haplotype systems increases the informativity of linkage-based tests for prenatal diagnosis and carrier screening in PKU families.

Alleles↗
PubMed2006

An intravital microscopy method permitting continuous long-term observations of ovulation in vivo in the rabbit.

BACKGROUND: A method for intravital microscopy of the rabbit ovary was developed to enable observations of real-time changes during ovulation in vivo. The aim was to correlate these events to biochemical events at specific stages of ovulation. METHODS: Virgin, female rabbits were primed with equine chorionic gonadotrophin (CG) (30-100 IU) then HCG (100 IU) 2 days later to induce ovulation. During anaesthesia, the right ovary was surgically exteriorized and submerged in an organ chamber with a microscopy lens positioned close to the ovary. Continuous video recordings were performed. RESULTS: Initial equine CG priming experiments revealed the highest ovulation rate, without premature luteinization, after 30 IU equine CG. This priming protocol subsequently demonstrated follicular ruptures 11.5-14 h after HCG. Numbers of ovulations from the exteriorized and contralateral non-exteriorized ovary were similar. The sequence of typical features of ovulation was: shutdown of microcirculation in the follicular apex, formation of petechiae in the follicular wall and a cone-shaped structure over the future rupture site, marked bleeding in connection with follicular rupture and a fairly steady extrusion velocity of granulosa cells and the oocyte. CONCLUSION: This method captured a sequence of structural changes during ovulation. It could be combined with blood and follicular fluid sampling for biochemical analysis and could be used in studies on biochemical reactions in relation to specific changes in the follicular structure during ovulation.

Animals↗