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PubMed1995

Interdependence of pathogenicity and replicability with potato spindle tuber viroid.

After the unexpected appearance of lethal symptoms on tomato plants infected with the PSTVd strain Intermediate Di, viroids were isolated and sequenced. It was found that a new strain, named RG 1, had been generated spontaneously in our greenhouse. In a different series of plant passages two new strains, named QF A and QF B, were detected which coexisted with the wild-type strain Di. Strains QF A and QF B showed intermediate symptoms when inoculated separately. In order to confirm the working hypothesis that the more pathogenic strain outcompetes the less pathogenic strain but strains of similar pathogenicity might coexist in the host, strains of different pathogenicity were mixed for inoculation in a ratio from 1:1 to 1:100 (more pathogenic:less pathogenic). The concentrations of the individual strains were determined 6 weeks postinfection with the method of nondenaturing polyacrylamide gel electrophoresis, and the working hypothesis was confirmed. The total concentrations of viroids in infected plants were very similar, irrespective of whether severe, intermediate, or mild strains or mixtures of different strains were present. The mutations in all new strains (3 in RG 1, 2 in QF A, 3 in QF B) were located in the so-called virulence-modulating region. The mutations of strain RG 1 influenced dramatically the thermodynamic stability of the native rod-like structure, as determined experimentally by temperature-gradient gel electrophoresis. Since during replication a multihairpin structure is generated transiently which is transformed afterwards into the rod-like structure, a lower thermodynamic stability of the rod-like structure leads to a higher accumulation of the transient structure. It is assumed that the transient structure, which is active in replication as shown earlier, is essential also in pathogenesis. This model explains the experimentally determined interdependence between pathogenicity and replicability of PSTVd strains.

Base Sequence↗

PubMed2002

Polymorphism in the infectious salmon anemia virus hemagglutinin gene: importance and possible implications for evolution and ecology of infectious salmon anemia disease.

Infectious salmon anemia (ISA) is an emerging disease in farmed Atlantic salmon with important commercial consequences. The pathogenicity of the ISA virus (ISAV; an orthomyxovirus) varies, observed as differences in disease development and clinical signs. A small polymorphic region (PR) in the ISAV genomic segment encoding the hemagglutinin (HA) has been described. An analysis of 33 HA gene sequences from historical and recent ISA outbreaks was performed, added to a selection of previously published HA sequences. A differential deletion model explaining the generation of HA polymorphism is proposed. The European ISAV sequences could be grouped according to deletion patterns in PR. Cell-culture replication and cytopathic effect varied between viruses from different PR groups. A rather complex epidemiology is suggested, as (a) HA sequences representing several PR variants were detected in three samples; (b) identical mutations occurred in different genetic lineages; and (c) large genetic differences were present in closely related viruses.

Amino Acid Sequence↗

PubMed1992

Potentiation of contraction as related to changes in free and total intracellular calcium.

In voltage-clamped guinea-pig ventricular myocytes, we studied the potentiation of contraction in dependence on the concentration of intracellular calcium; ionized calcium [Ca2+]c was measured by Indo-1 microfluospectroscopy and total calcium (sigma Ca) by electronprobe microanalysis (EPMA). After a 15 min rest period, [Ca2+]c was approx. 90 nM and sigma Ca was below the detection limit (80 microM) in myoplasm (sigma Ca(myo)), junctional sarcoplasmic reticulum (sigma CaSR) and mitochondria (sigma Ca(Mito)). Post rest, repetitive clamp steps (1 Hz) potentiated extent and rate of shortening by 300%. In the literature, post-rest potentiation is attributed to the replenishment of SR with releasable calcium; by EPMA the postulated increase in sigma CaSR was measured directly. Post-rest, the peaks of systolic [Ca2+]c transients increased, however only by 40%. In addition, a moderate increase of end-diastolic [Ca2+]c was measured. In an other series of experiments, contraction was potentiated by 800% increase by means of paired voltage-clamp pulses (1 Hz, 36 degrees C, 2 mM [Ca2+]o). In the potentiated state, end-diastolic [Ca2+]c was 180 nM and sigma Ca(myo) was 0.65 mM. During systole, [Ca2+]c peaked within 20 ms to 950 nM. sigma Ca(myo) rose within 20 ms to 1.4 mM and fell within 40 ms to 1.1 and within 90 ms to 0.8 mM. In contrast, the time course of contraction was slow and peaked at a time (130 ms) when the [Ca2+]c and sigma Ca(myo) transients were finished. We suggest that Ca2+ bound to troponin C (TnC) controls only the onset but not the time course of myofilament interaction. From [Ca2+]c and sigma Ca(myo) we estimated a Ca2+ buffering capacitance of 1.5 mmol sigma Ca(myo) per pCa change, only a fraction of which can be attributed to Ca2+ binding sites on TnC. A model explaining the results requires the assumption of 0.6 mM additional slow, high affinity Ca2+ sites and 2 mM fast, low affinity Ca2+ sites. We discuss that end-diastolic Ca2+ binding to these sites contributes to the potentiation of contraction. Junctional SR. At the end of diastole sigma CaSR was 2.4 mM which is 4 times larger than sigma Ca(myo). This difference disappeared 20 ms after depolarization (sigma CaSR 1.1 mM), within another 20 ms it largely recovered (sigma CaSR 2.0 mM). These properties suggest that the junctional SR is a compartment suitable not only for Ca2+ release but also for rapid Ca2+ reuptake. Mitochondria. Paired-pulse potentiation increased end-diastolic sigma Ca(Mito) significantly (0.4 mM).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2000

Titin elasticity in the context of the sarcomere: force and extensibility measurements on single myofibrils.

Skeletal-muscle titin contains in its I-band section two main elastic elements, stretches of Ig-like domains and the PEVK segment. Both elements contribute to the extensibility and passive force development of relaxed skeletal muscle fibers during stretch. To explore the nature of elasticity of the segments, their force-extension relation was determined with immunofluorescence and immunoelectron microscopy, combined with isolated myofibril mechanics. The results were then fitted with recent models of biopolymer elasticity. Whereas an entropic-spring mechanism may account for the elasticity of the Ig-domain segments, PEVK-titin elasticity appears to have both entropic and enthalpic origins. The modeling explains why the two elements extend sequentially upon stretch: elongation of the Ig-domain regions (with folded modules) is followed by unraveling of the PEVK domain. I-band titin in cardiac muscle is expressed in two main isoforms, N2-A and N2-B. The N2-A isoform is similar to that found in skeletal muscle, whereas the N2-B titin is distinguished by cardiac-specific Ig-motifs and nonmodular sequences within the central I-band section. By examining the extensibility of N2-B titin, it was found that this isoform extends by recruiting three distinct elastic elements: poly-Ig regions and the PEVK domain at low to modest stretch, and in addition, a unique 572-residue sequence insertion at higher physiological stretch. Extension of all three elements allows cardiac titin to stretch fully reversibly at physiological sarcomere lengths, without the need to unfold individual Ig domains.

Animals↗

PubMed1992

Factors affecting the rate of T-DNA transfer from Agrobacterium tumefaciens to Nicotiana glauca plant cells.

Different factors involved in the early steps of the T-DNA transfer process were studied by using a beta-glucuronidase gene (gusA) as a reporter in Nicotiana glauca leaf disc transformation experiments. The levels of transient expression of the gusA gene in leaf discs infected with several strains or vir mutants correlated well with their virulence phenotype, except for virC mutants. The rate of T-DNA transfer was shown to be stimulated in the case of non-oncogenic strains by the co-transfer of small amounts of oncogenic genes. It was found that the location of the T-DNA in the Agrobacterium genome affected the T-DNA transfer rate especially in virC mutants. The virC mutants transferred the gusA-containing T-DNA located on a binary vector more efficiently than the oncogenic T-DNA of the Ti plasmid. Although wild-type strains induced high levels of gusA expression early after infection, the gusA expression appeared to be lost late after infection in the infected leaf discs. In contrast, in leaf discs infected by virC mutants the level of gusA expression increased steadily in time. A model explaining these results is presented.

Agrobacterium tumefaciens↗

PubMed1982

The kinetics of DNAse inhibition by specific antibodies.

The inhibition of beef pancreatic deoxyribonuclease I activity with specific antibodies is studied using the hypochromic shift of DNA at 260 nm. The kinetics of this reaction reveals two reaction phases. The first phase, which ends within seconds, is reversible and follows second order kinetics. It leads quickly to the formation of big complexes. The second phase, which reaches completion within minutes before precipitation is detectable, is essentially irreversible and follows zero order kinetics. A model explaining these results is suggested.

Animals↗

PubMed1987

Gene organization of haplotypes expressing two different C4A allotypes.

The gene organization of C4 haplotypes expressing two different C4A allotypes with a C4B null allele (C4A3A2BQ0 and C4A3A6BQO) was studied using Southern blot analysis with cDNA probes and restriction enzymes which give C4A and C4B locus-specific restriction fragments. These haplotypes were shown to have both a C4A and a C4B locus present, suggesting that the C4B locus expresses a C4A protein. The finding of a 21-OH A and a 21-OH B gene on the C4A3A6BQO haplotype further suggests that this haplotype has the common gene organization C4A, 21-OH A, C4B, 21-OH B. A model explaining C4 null alleles on haplotypes found to have two C4 loci is presented.

Alleles↗

PubMed1990

A reanalysis of the impact of non celebrity suicides. A research note.

Previous work on suicide and the media has neglected theoretical issues. Some work has implied that only celebrity suicides can be expected to trigger additional suicides in the real world. The present study focuses on non celebrity suicides. Correcting coding errors in a previous work, it finds that the suicides of non celebrities are associated with increases in the national suicide rate. An index of publicized celebrity suicide stories was, however, more closely associated to increases in suicide than the publicized non celebrity stories. The model explains 90 percent of the variance in monthly suicide rates.

Cross-Sectional Studies↗

PubMed1993

Effectiveness of family notification efforts and compliance with measles post-exposure prophylaxis.

Exposures to measles in medical settings have contributed to the recent resurgence of the disease in the United States. Following a measles exposure in two pediatric medical facilities serving an inner-city population, we investigated the effectiveness of a disease notification strategy and compliance of the exposed population with recommendations for post-exposure prophylaxis, two requirements of a successful intervention program. Of 106 families with children eligible for a prophylactic vaccination by standard guidelines, 64% were notified of exposure by telephone. Compliance was assessed by a brief telephone questionnaire based upon the Health Belief Model, and verified by medical records. Forty-six families were interviewed regarding their decisions to comply with the recommendations. Most (75%) families were compliant. Compliant parents perceived measles to be severe and their children to be in excellent health. In a multiple logistic regression analysis, only the perceived severity of measles significantly contributed to the model. We conclude that: infection control outreach may need to extend beyond telephone notification for an inner-city population, and that once notified, most people will comply with recommendations. The Health Belief Model explains compliance with infection control measures and may be useful in guiding public health interventions.

Communication↗

PubMed1977

Dislodgeable residues of ethion in Florida citrus and relationships to weather variables.

Five different treatments of ethion on Valencia orange trees were compared for decay rates and for ethion monoxon and ethion dioxon production under different environmental conditions. The oxon metabolite levels observed were low and always below the residue level of ethion itself. There were no significant differences in the decay rates of ethion between treatments. A model of ethion decay utilizing environmental variables as a time base is presented. This model explains 94% of the variation observed in ethion decay during very wet and very dry periods in Florida. The application of these results and general experimental approach to worker safety reentry standards is discussed.

Chromatography, Gas↗

PubMed1984

Nucleosome "phasing" and cruciform structures in circular supercoiled pBR322 DNA.

Cruciform structures have been detected in pBR322 supercoiled DNA, both in its naked state and when complexed with histone octamer, using S1 endonuclease cleavage and EcoRI restriction. An inspection of the DNA sequence shows that the S1-hypersensitive sites are very near to AT-rich regions of pBR322 genome. A nucleosome "phasing" in these regions, as found on AT-rich regions of SV40 DNA (15), has been shown by restriction enzymes analysis. On the basis of these results it can be proposed that cruciform structures protrude on the nucleosome surface. This model explains the reason why these structures, which need high superhelical density, can exist in supercoiled DNA partially relaxed by nucleosome formation.

Base Sequence↗

PubMed2003

Angiotensin-converting enzyme genotype, albuminuria and plasma fibrinogen in type 2 diabetes mellitus.

AIMS: Increased fibrinogen level is considered an important atherosclerosis risk factor. Patients with type 2 diabetes frequently have increased fibrinogen levels. The aim of the present study was to examine the effect of angiotensin-converting enzyme (ACE) gene polymorphism and the effects of the diabetic environment on plasma fibrinogen in type 2 diabetes. PATIENTS AND METHODS: The study group included 125 patients with type 2 diabetes (40 men, 85 women). The average age of patients was 62 +/- 10 years. Fibrinogen concentration was determined with the thrombin coagulation test. ACE insertion/deletion (I/D) polymorphism was detected using polymerase chain reaction (PCR) assay. RESULTS: II homozygotes (n = 17) had the highest mean fibrinogen levels, ID heterozygotes (n = 75) had medium levels and DD homozygotes (n = 33) had the lowest (p = 0.054, ANOVA). II homozygotes also had significantly higher mean fibrinogen level than ID/DD carriers (4.3 +/- 1.7 vs. 3.5 +/- 1.3 g/l; p = 0.015). The indices of renal functions, i.e. albuminuria (r = 0.37; p < 0.0001) and serum creatinine (r = 0.22; p = 0.015), significantly correlated with fibrinogen levels. The correlation between albuminuria and fibrinogen was significant in the subgroups with genotypes II (r = 0.76; p = 0.001) and ID (r = 0.37, p = 0.002), whereas in the subgroup of DD homozygotes this relationship did not reach statistical significance. In the multivariate regression analysis with age, sex, BMI, creatinine, albuminuria and ACE genotype as independent variables, albuminuria was the only significant predictor of fibrinogen level (p < 0.0001). After interaction between the ACE genotype and albuminuria was included into multivariate analysis, the interaction became the only independent predictor of plasma fibrinogen level (p < 0.0001) in the model, and the model explained 25% of the plasma fibrinogen variance. CONCLUSION: ACE gene polymorphism is associated with plasma fibrinogen level in type 2 diabetes. This association is mediated by an interaction between ACE genotype and albuminuria. Diabetes patients with genotypes II or ID have increased plasma fibrinogen in the presence of albuminuria.

Aged↗

PubMed2006

Translation control of UCP2 synthesis by the upstream open reading frame.

Uncoupling protein 2 (UCP2) belongs to a family of transporters of the mitochondrial inner membrane. In vivo low expression of UCP2 contrasts with a high UCP2 mRNA level, and induction of UCP2 expression occurs without change in mRNA level, demonstrating a translational control. The UCP2 mRNA is characterized by a long 5' untranslated region (5'UTR), in which an upstream open reading frame (uORF) codes for a 36-amino-acid sequence. The 5'UTR and uORF have an inhibitory role in the translation of UCP2. The present study demonstrates that the 3' region of the uORF is a major determinant for this inhibitory role. In this 3' region, a single-base substitution that kept the codon sense unchanged significantly modified UCP2 translation, whereas some important amino acid changes had no effect. We discuss our results within the framework of the existing models explaining initiation of translation downstream of a uORF.

5' Untranslated Regions↗

PubMed1997

[Potassium ion secretion and generation of the endocochlear potential in the stria vascularis].

Central to inner ear research are questions regarding the homeostasis of the high endolymphatic potassium concentration (approximately 150 mmol/l) and the high endocochlear potential (approximately +80 mV). Disturbances of the endocochlear potential can lead to the immediate loss of hearing which may be irreversible. The molecular mechanism leading to the generation of the endocochlear potential has not yet been discovered in spite of its clinical relevance. It is long known, however, that the stria vascularis is responsible for both the generation of the endocochlear potential as well as the secretion of potassium into endolymph. Recent investigations have clarified the mechanisms leading to the secretion of potassium and have led to the formulation of a now widely accepted model. This model explaining potassium secretion as well as the generation of the endocochlear potential is discussed in the present article.

Animals↗

PubMed2003

Identification of QTL for growth- and grain yield-related traits in rice across nine locations of Asia.

Rice double-haploid (DH) lines of an indica and japonica cross were grown at nine different locations across four countries in Asia. Genotype-by-environment (G x E) interaction analysis for 11 growth- and grain yield-related traits in nine locations was estimated by AMMI analysis. Maximum G x E interaction was exhibited for fertility percentage number of spikelets and grain yield. Plant height was least affected by environment, and the AMMI model explained a total of 76.2% of the interaction effect. Mean environment was computed by averaging the nine environments and subsequently analyzed with other environments to map quantitative trait loci (QTL). QTL controlling the 11 traits were detected by interval analysis using mapmaker/qtl. A threshold LOD of >/=3.20 was used to identify significant QTL. A total of 126 QTL were identified for the 11 traits across nine locations. Thirty-four QTL common in more than one environment were identified on ten chromosomes. A maximum of 44 QTL were detected for panicle length, and the maximum number of common QTL were detected for days to heading detected. A single locus for plant height (RZ730-RG810) had QTL common in all ten environments, confirming AMMI results that QTL for plant height were affected the least by environment, indicating the stability of the trait. Two QTL were detected for grain yield and 19 for thousand-grain weight in all DH lines. The number of QTL per trait per location ranged from zero to four. Clustering of the QTL for different traits at the same marker intervals was observed for plant height, panicle number, panicle length and spikelet number suggesting that pleiotropism and or tight linkage of different traits could be the possible reason for the congruence of several QTL. The many QTL detected by the same marker interval across environments indicate that QTL for most traits are stable and not essentially affected by environmental factors.

Asia↗

PubMed1999

A comparison of psychiatric casemix in the UK and Italy.

BACKGROUND: The objective of this study was to compare casemix groups in Italy and the UK. Three hypotheses were tested. First, that length of stay would be shorter in Italy. Second, that diagnosis would not be an effective predictor of length of stay. Third, that diagnosis-based groups would be better predictors of length of stay in Italy due to shorter in-patient episodes. METHODS: In-patient episodes in Pavia (Italy) and Camberwell (UK) for patients with psychosis were allocated to four Healthcare Resource Groups. Average lengths of stay, and coefficients of variation in the two areas were compared. A regression model was constructed to determine the impact of diagnosis groups, gender, age and area on length of stay. RESULTS: Length of stay was significantly shorter in Pavia than in Camberwell for three of the four groups. The coefficient of variation was generally above 1, indicating a lack of within-group similarity. With outliers trimmed, the figures were below 1, except for one group in Camberwell. Pavia revealed greater group homogeneity than Camberwell, with one exception. The regression model explained 9% of variation when the two areas were both included, and around 5% when compared separately. Age had a non-linear impact on length of stay in Camberwell. CONCLUSIONS: We have again shown that diagnosis does not adequately predict length of stay. However, in Italy, where admissions are for shorter periods, diagnosis groups are more homogeneous. This may be because the initial part of a hospital stay is due to clinical factors, whereas prolonged stay is influenced by supply-side issues.

Adult↗

PubMed2000

Sociocultural contexts of anthropophobia: a sample of Chinese youth.

BACKGROUND: Anthropophobia, a subtype of social phobia, is prevalent in Chinese and Japanese societies. This study investigated sociocultural influences on the course of this culturally specific mental disorder. METHOD: One hundred and fifty subjects, including 50 anthropophobic, 50 neurasthenic, and 50 community subjects, were interviewed in Beijing, China for the assessment of their early life experiences (child-parent relationships and sexual experiences), collectivism disposition, sexual attitudes, and communication behaviors. Logistic and linear regression analyses were performed to examine significant predictors of the occurrence and the symptom level of anthropophobia. RESULTS: Regression models explained 69% of variance in the diagnosis and 57% of variance in the symptom level of anthropophobia among anthropophobic and community subjects. They also explained 48% and 47% of variance respectively in the diagnosis and the level of symptoms among anthropophobic and neurasthenic subjects. Anthropophobic subjects had more problematic relationships with parents than did community and neurasthenic subjects. They also exhibited significantly stronger characteristics of collectivism than did community subjects. Sexual contact with a non-family member prior to age 19 and a feeling of discomfort when interacting with the opposite sex were significantly associated with the diagnosis and symptom level of anthropophobia. CONCLUSIONS: It was concluded that anthropophobic subjects' early sexual experiences and need for parental approval shaped their conformity to social norms and negative sexual attitudes, which were reinforced by the collective-orientated cultural environment, and contributed to the development of anthropophobia.

Adult↗

PubMed2003

Bone turnover markers during lactation, postpartum amenorrhea and resumption of menses.

Changes in bone turnover, and consequent bone loss and recovery during lactation and the postweaning period, are likely modulated by varying estrogen levels inherent in these time periods. To address this question we measured serum biochemical markers of bone formation (bone-specific alkaline phosphatase, amino-terminal propeptide of type I procollagen, osteocalcin), of bone resorption (type I collagen carboxy-terminal telopeptide), and serum female sex hormones (estradiol, luteinizing hormone and follicle-stimulating hormone) in 32 healthy mothers prospectively after delivery, 3 months postpartum, after postpartum amenorrhea and 1 year after resumption of menses. During postpartum amenorrhea (mean 5.7, SD 2.9 months) bone mineral density decreased significantly, some 2% at the lumbar spine and some 3% at the femoral neck, but subsequently recovered completely at the former site and partially at the latter. Bone turnover marker levels were elevated at parturition and still at the end of postpartum amenorrhea. Subsequent to parturition the bone resorption marker level showed a decreasing trend while the formation marker levels continued increasing, and eventually coincided with the resorption level within the very first months postpartum. Both lactation and hormonal status modulated bone turnover marker levels. Maternal age was positively associated with increased bone turnover. Interestingly, higher parity and longer history of previous lactation were associated with lower bone turnover marker levels postpartum as compared with previously nulliparous women of the same age. The regression models explained typically some 20-30% of the variability in the bone turnover marker levels. The dynamic pattern in bone turnover is dissimilar to that occurring at menopause and it indicates that the bone loss most likely occurs in the beginning of postpartum period. It also seems that estrogen has a specific influence on bone turnover only during the first months of lactation.

Adult↗