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PubMed1991

Evolutionary analysis of the influenza A virus M gene with comparison of the M1 and M2 proteins.

Phylogenetic analysis of 42 membrane protein (M) genes of influenza A viruses from a variety of hosts and geographic locations showed that these genes have evolved into at least four major host-related lineages: (i) A/Equine/prague/56, which has the most divergent M gene; (ii) a lineage containing only H13 gull viruses; (iii) a lineage containing both human and classical swine viruses; and (iv) an avian lineage subdivided into North American avian viruses (including recent equine viruses) and Old World avian viruses (including avianlike swine strains). The M gene evolutionary tree differs from those published for other influenza virus genes (e.g., PB1, PB2, PA, and NP) but shows the most similarity to the NP gene phylogeny. Separate analyses of the M1 and M2 genes and their products revealed very different patterns of evolution. Compared with other influenza virus genes (e.g., PB2 and NP), the M1 and M2 genes are evolving relatively slowly, especially the M1 gene. The M1 and M2 gene products, which are encoded in different but partially overlapping reading frames, revealed that the M1 protein is evolving very slowly in all lineages, whereas the M2 protein shows significant evolution in human and swine lineages but virtually none in avian lineages. The evolutionary rates of the M1 proteins were much lower than those of M2 proteins and other internal proteins of influenza viruses (e.g., PB2 and NP), while M2 proteins showed less rapid evolution compared with other surface proteins (e.g., H3HA). Our results also indicate that for influenza A viruses, the evolution of one protein of a bicistronic gene can affect the evolution of the other protein.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1990

Implications of gene amplification for evolution and management of insecticide resistance.

Simulations were used to compare evolution of insecticide resistance predicted by a conventional two-allele model with predictions from three- and four-allele models that assume resistance is based on gene amplification. Results were similar between models when insecticide concentration was low or moderate. In contrast, when 10% of the population was not exposed to insecticide each generation, high insecticide concentrations slowed resistance development in the two-allele model, but caused rapid development of high levels of resistance in the three- and four-allele models. The presence of a third allele at an initial frequency as low as 10-7 doubled or tripled the rate of resistance development in some cases. Attempts to slow evolution of resistance by overwhelming it with high concentrations of insecticides are not likely to succeed if gene amplification or other mechanisms generate alleles that confer high levels of resistance.

Alleles↗
PubMed2025

Haplotype-resolved telomere-to-telomere genome assembly of Populus lasiocarpa unveils retrotransposon-driven centromere evolution.

Centromeres, essential for chromosome segregation, exhibit remarkable evolutionary dynamism in sequence composition and structural organization. Here, we report the first haplotype-resolved, telomere-to-telomere genome assembly of Populus lasiocarpa (PLAS) and precisely map all 38 functional centromeres through CENH3 ChIP-Seq. Unlike classical satellite-rich centromeres in model plants, PLAS centromeres lack abundant satellite arrays but are dominated by retrotransposons, particularly RLG and RIL elements, which form intricate nested TE arrays within the functional centromeric regions, disrupting their structural integrity and driving their evolution. Comparative analysis with P. trichocarpa reveals a conserved retrotransposon-dominated architecture, despite minimal sequence conservation. We propose a cyclic model of centromere evolution in which autonomous retrotransposons destabilize functional centromeres through epigenetic erosion, triggering neocentromere formation at pericentromeric sites enriched in transposable elements (TEs) and tandem repeats (TRs). These neocentromeres either succumb to recurrent retrotransposon invasions or stabilize through KARMA-mediated TR expansion, ultimately giving rise to satellite-rich centromeres. Our work redefines centromeres as dynamic, epigenetically plastic domains shaped by retrotransposon-TR antagonism, challenging the satellite-centric paradigm and offering novel insights into plant genome evolution.

Retroelements↗
PubMed1990

Comparative in vitro activities of 20 fluoroquinolones against Mycobacterium leprae.

The in vitro activities of 20 fluoroquinolones against Mycobacterium leprae were evaluated by using the BACTEC 460 system. M. leprae was incubated in BACTEC 12B medium at 33 degrees C under reduced oxygen for 2 to 3 weeks in the presence of fluoroquinolones at 0.31 to 5 micrograms/ml. Activity was determined by a reduction in 14CO2 evolution compared with that of drug-free controls. Of the commercially available agents, ofloxacin was most active, while enoxacin and norfloxacin were inactive. However, a number of newer fluoroquinolones (AT-4140, OPC-17100, OPC-17066, PD-117596, PD-124816, PD-127391, and WIN-57273), all containing a cyclopropyl group at R-1 and, with the exception of WIN-57273, either a halogen or methyl group at R-8, were more active than ofloxacin in vitro. Further in vivo evaluations of these agents should help determine their potential for use against leprosy.

4-Quinolones↗
PubMed1988

Significance of extra 18q- chromosome in Japanese t(14;18)-positive lymphoma.

Karyotype evolution of t(14;18)-positive lymphoma was studied in 13 Japanese patients. The extra 18q- chromosome, found in six of ten patients with complex karyotypes, was the most common change subsequent to a t(14;18)(q32;q21) chromosome translocation. The additional change was interpreted as being a duplication of an 18q- derived from a t(14;18). The six patients had transformed histology of follicular small cleaved cell lymphoma or diffuse large cell lymphoma, and five of them had extranodal expansion associated with a poor prognosis. These findings indicate that the extra 18q-, together with other chromosome abnormalities, is closely associated with the advanced grade disease of t(14;18)-positive lymphoma, and the extra chromosome is evolutionally comparable with the second Philadelphia (Ph1) chromosome often found in the blastic phase of chronic myelocytic leukemia carrying a t(9;22)(q34;q11). In addition, since the extra 18q- is rarely found in American patients with t(14;18)-positive lymphoma, there appears to be a difference in the karyotype evolution between Japanese and American patients.

Chromosome Aberrations↗
PubMed1985

Comparative study of DHBV DNA levels and endogenous DNA polymerase activity in naturally infected ducklings in France.

Duck hepatitis B virus (DHBV) was found in the serum of 1-6% of Pekin ducklings originated from French commercial flocks. The viremia was followed in the serum of 5 ducklings over a span of 3 mth by monitoring the levels of DHBV DNA and the endogenous DNA polymerase (DNAp) activity. The DHBV DNA levels in serum were quantified either by the DNA dot hybridization technique including counting of retained radioactivity, or by successive dilutions of each serum sample followed by DNA hybridization. The counting of the retained radioactivity was plotted on a curve and its evolution compared with that of viral DNAp activity. DHBV DNA levels in serum, estimated by both methods paralleled those of the DNAp activity, which peaked at the 4th or 5th week posthatch to decrease and fluctuate thereafter. Occasional discordance between DHBV DNA levels and the endogenous DNAp activity was observed, which could be correlated with the degree of repair of the single stranded gap of serum DHBV DNA. Parallel follow up studies comparing quantitative estimations of serum viral DNA and of DNAp activity, as presented here, may provide some clues for the understanding of the mechanisms involved in the establishment of the HEPA DNA virus carrier state. Such comparative studies may also be crucial for optimal monitoring of antiviral drugs in both human clinical trials and animal experimental studies.

Animals↗
PubMed1978

Purification and partial characterization of the B subunit of Serratia marcescens tryptophan synthetase.

A trpE mutant of Serratia marcescens (E-7) was isolated, and the multimeric enzyme tryptophan synthetase (EC 4.2.1.20) was purified to homogeneity from derepressed cells. The A and B subunits were resolved, and the B subunit was partially characterized and compared with the Escherichia coli B subunit as part of a comparative evolution study of the trpB cistron of the trp operon in the Enterobacteriaceae. The S. marcescens B subunit is a dimer (beta(2)), and its molecular weight was estimated to be 89,000. The separate subunits (beta monomers) had molecular weights of approximately 43,000. The B subunit required pyridoxal phosphate for catalytic activity and had an apparent K(m) of 9 x 10(-6) M. The N terminus of the B subunit was unavailable for reaction with terminal amine reagents (blocked), whereas carboxypeptidase digestion released a C-terminal isoleucine. Using S. marcescens B antiserum in agar immunodiffusion gave an almost complete reaction of identity between the B subunits of S. marcescens and E. coli. The antiserum was used in microcomplement fixation, allowing for a comparison of the overall antigenic surface structure of the two B subunits. The index of dissimilarity for the heterologous E. coli enzyme compared with the homologous S. marcescens enzyme was 2.4, indicating extensive similarity of the two proteins at their surfaces. Comparative antiserum neutralization of B-subunit enzyme activity showed the E. coli enzyme to cross-react 85% as well as the S. marcescens enzyme. With regard to the biochemical and immunochemical parameters used in this study, the S. marcescens and E. coli B subunits were either identical or very similar. These findings support the idea that the trpB cistron of the trp operon is a relatively conserved gene in the Enterobacteriaceae.

Amino Acids↗
PubMed1988

Photodegradation paths of cefotaxime.

The degradation kinetics of cefotaxime sodium salt in aqueous solution, under UV light at 254 nm, was investigated by HPLC and antibiotic activity. This degradation is the result of two competitive processes, an isomerization and a photolysis. This study is mostly about the isomerization step. The measured quantum yields for the cefotaxime to its anti-isomer and anti-isomer to cefotaxime isomerizations are, respectively, 0.10 and 0.12. A photostationary state characterized by an anti:syn ratio of 1.2 is obtained after 30 min of irradiation. The competitive photolysis, which actually consists of at least two processes (one on the delta 3-cephem ring and the second on the methoxyimino group), leads to an intense yellowing of the solution corresponding to the destruction of the molecule. The comparative evolution of the absorption spectra, under irradiation at 254 nm, of cefotaxime, thiazoximic acid, and 7-aminocephalosporanic acid shows that it is the delta 3-cephem ring photolysis which gives the yellow color. The major conclusion of this work is to call attention to the photoisomerization step which leads efficiently to the inactive anti-isomer, without giving any visible notice of degradation. Such a process is to be expected in all antibiotics containing an alkoxyimino linkage on the C-7 substitution.

Biological Assay↗
PubMed2025

The telomere-to-telomere genome of Sanicula chinensis unveils genetic underpinnings of low furanocoumarin diversity and content in one basal lineage of Apiaceae.

Furanocoumarins are specialized defense compounds in Apiaceae, but the evolutionary path of their biosynthesis is not well understood. We generated a telomere-to-telomere (T2T) genome for Sanicula chinensis, an early-diverging species within the Saniculoideae subfamily, to explore its evolution. Comparative genomics revealed that S. chinensis and Apioideae species each underwent unique whole-genome duplication (WGD). Unlike most species in the Apioideae subfamily, S. chinensis produces a limited diversity and content of furanocoumarins but shows high esculetin levels. This metabolic profile likely stems from three genetic factors: elevated expression of p-Coumaroyl ester 3'-hydroxylase (C3'H) and hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyl transferase (HCT), which shift the metabolic pathway toward simple coumarins; the absence of a key biosynthetic gene cluster, including prenyltransferase (PT) and p-coumaroyl-CoA 2'-hydroxylase (C2'H), found in Apioideae; and incomplete or inactive PT enzymes in S. chinensis. Our results not only shed light on the evolutionary history of furanocoumarin biosynthesis in Apiaceae, but also provide avenues for tailoring furanocoumarin content for agricultural or medical applications in plants.

Furocoumarins↗
PubMed1991

Myeloperoxidase and elastase as markers of leukocyte activation during cardiopulmonary bypass in humans.

To assess leukocyte activation during cardiopulmonary bypass, we measured white blood cell and neutrophil counts and lysosomal enzyme release, especially myeloperoxidase and elastase, throughout the operation and for 5 days postoperatively. A newly developed double antibody radioimmunoassay of myeloperoxidase and an enzyme-linked immunosorbent assay for detection of the polymorphonuclear elastase-alpha 1-proteinase inhibitor complex were used to determine their plasma levels in 15 patients undergoing elective aorta-coronary bypass grafting. Preoperatively white blood cell counts and plasmatic levels of myeloperoxidase and elastase-alpha 1-proteinase inhibitor were normal. Because no correlation has yet been established between levels of myeloperoxidase and elastase-alpha 1-proteinase inhibitor, the aim of this prospective study was to evaluate the use of these enzyme levels as markers for leukocyte activation in vivo. We addressed the clinical situation of cardiopulmonary bypass because it offered the possibility of monitoring the comparative evolution of blood levels of these enzymes in parallel to white blood cell counts through well-defined steps corresponding to known events. We document the advantages of myeloperoxidase blood levels over elastase measurement as reflecting more rapidly the in vivo activation of leukocytes. The time course kinetics of these three measurements were not parallel. White blood cell counts remained stable at the beginning of bypass, whereas myeloperoxidase levels increased sharply and continuously as soon as bypass was instituted until the end of bypass. Elastase levels also increased, but later than myeloperoxidase, beginning when the patients was rewarmed. High elastase plasma levels persisted later than myeloperoxidase after bypass, in parallel with white blood cell counts. It thus clearly appears that changes in myeloperoxidase levels more rapidly reflect the activation state of leukocytes induced by cardiopulmonary bypass and surgery, whereas peak levels of elastase were delayed and parallel to white blood cell counts. From this model, in which the evolution of leukocyte numbers could be followed in relation with known steps of stimulation, it appears that myeloperoxidase is a sensitive marker for monitoring in vivo activation of white blood cells.

Adult↗
PubMedDate not supplied

Prognostic value of preoperative tests in the surgical treatment of ascites with the implant of Le Veen shunts in cirrhotics.

In the period of January 1978 to October 1988, 32 Le Veen shunts (LVS) were implanted in 20 patients, out of which 16 were alcoholic cirrhotics and 4 postnecrotic cirrhotics. In the present study, we correlated preoperative laboratory data of these patients with their postoperative evolution, comparing the clinical results of patients who survived more than 30 days (13 patients = 65%) with the results of those who died within the same period (7 patients = 35%). For that matter, 14 laboratory tests were performed in order to measure the serum levels of hematocrit, hemoglobin, urea, creatinine, sodium, potassium, bilirubin, albumin, AST, ALT, alkaline phosphatase, fibrinogen, gamma GT and prothrombin activity. After statistical analysis, we observed that 6 of the 14 tests performed could be considered of prognostic value in the following decreasing order of importance: fibrinogen, alkaline phosphatase, prothrombin activity, urea, gamma GT and bilirubin. We observed that all the 7 patients who died prematurely presented 3 or more of these levels altered, when compared with standard values. Based on these data, we concluded that serum levels of fibrinogen, alkaline phosphatase, urea, gamma GT, bilirubin and activity of prothrombin proved to be important factors in determining the prognosis of immediate survival in cirrhotic patients who underwent LVS implantation. We also concluded that when 3 or more of these factors are altered, the implant of LVS is contraindicated, whatever clinical criteria for indication and contraindication were taken into account.

Adult↗
PubMed1989

[New occult choroidal vessels in age-related macular degeneration].

We studied the clinical characteristics and the natural course of occult choroidal new vessels (CNV) in 78 eyes with age-related macular degeneration (AMD). Cases were included in 2 groups characterized respectively by ill-defined subretinal ooze (group 1) and serous detachment of the retinal pigment epithelium (RPE) with adjacent areas of mottled pigmentation (group 2). Both these forms of occult CNV showed to have a slower evolution compared to the classic CNV occurring in AMD, but they also led to disciform scar and severe visual loss. Occult CNV of group 2, contrary to those of group 1, were often multifocal and extrafoveal. They had a greater tendency to hemorrhages and a faster and less gradual progression to fibrovascular scarring and visual loss. Fluorescein angiography showed choroidal filling delay in the macular region of 47% of eyes of group 1. A perfusion defect of the macular choroid could be the basis of the low perfusion pressure and the consequent low activity of CNV with the angiographic pattern of ill-defined ooze.

Aged↗
PubMed1986

[Malignant non-Hodgkin's lymphoma associated with a serum monoclonal immunoglobulin].

Among the 394 non-Hodgkin's lymphomas (NHL) observed at our hospital over a thirteen year period, we have found 17 associated monoclonal gammopathies (4.3%). Fourteen gammopathies could be correlated to the lymphoid tumor due to a study of immunological membrane markers and to the comparative evolution of the disease and the monoclonal gammopathy. Two different groups could be distinguished: Six patients out of the fourteen studied (43%) had a gammopathy similar to the surface immunoglobulins of the tumour lymphoid cells. Seven of the seventeen showed, after treatment, a parallel evolution between the tumor and the gammopathy. This originates directly from the tumoral secretion and deserves to be classified among the B lymphoid excretory tumors. Six were IgM and one was IgG. Eight of the fourteen patients studied (57%) did not show any immunological relation between the lymphoma and the monoclonal gammopathy. The evolutions (10 of the 17 patients) of the tumor and of the gammopathy were independent. Among the eleven gammopathies (1 double gammopathy), 5 were IgG, 4 were IgA and 2 were IgM. The incidence of these gammopathies related to the total group tf lymphomas is 2.5%. Given the age of these patients, the association seems fortuitous.

Adult↗
PubMed1986

[Real-time ultrasonography in neurosurgery. Puncture of an intracranial hypoechogenic cavity].

The authors have been using real time echography in neurosurgical procedures since 1981: either for detection of a small sub-cortical tumor during a surgical operation, either for biopsy-guidance, or for puncturing a cavity (abscess, cyst or hematoma). The imaging is performed with a CGR SONEL 100 apparatus and two different frequency transducer elements: 3.5 MHz and 5 MHz. 56 patients underwent this technique; 22 times the lesion was hypoechoic: abscess give homogeneous, round hypoechoic image, often surrounded by a fine hyperechoic line; intracerebral hematoma produces an hypoechoic image after a 10 to 15 days evolution: compared to an abscess it then has a more hyperechoic irregular wave-like limit; tumoral-cyst echogenicity is very low; it can even be anechoic. If a stereotaxic structure exists, indication of real time echography must be limited to such stereotaxy contraindications: threatening intracranial hypertension, suppurated lesion, fragile patient. The technique has its limit: that is the small volume of the target-lesion (inferior to 10 mm); advantages must be emphasized: light procedure, satisfying confidence when considering the probe progression, sometimes better information than that of a CT-Scan examination especially for tumoral and cystic lesions.

Brain Abscess↗
PubMedDate not supplied

[Usefulness of CT in the evaluation of hematoma of the iliopsoas muscle in hemophiliacs].

Four iliopsoas hematomas in hemophiliacs are reported, evaluating the diagnostic role of CT. The specificity of the method is stressed in showing the morphological and densitometric patterns, which allow to localize the hematoma, to state the originating structures, and to follow its evolution. Comparing the obtained results to those found in literature, the authors suggest the use of CT in any hemophiliac in which a retroperitoneal hematoma is suspected.

Adolescent↗
PubMedDate not supplied

[Thermal test of reactive hyperemia: a propos of an objective study of pyridinol carbamate].

The thermal test of reactive hyperhemia (TTHR) gives a global and reliable appreciation of the cutaneous microcirculation, the importance of which is well known. In this study, sixty-one subjects were treated for from one month to one year with pyridinol-carbamate. The TTHR was modified in seventy-nine per cent of the cases, showing a considerable and lasting improvement. The clinical symptoms followed a comparable evolution.

Adult↗
PubMed1977

[Hyperglycinemia without ketosis. Biochemical and enzymatic study].

We report a biochemical and enzymatic study of two neonatal cases of non ketotic hyperglycinemia. We report the comparative evolution of glycine level in plasma and CSF during a restrictive diet excluding glycine and serine. The high levels of glycine found in CSF and brain are likely to reflect the brain damage. After autopsy, the glycine synthase activity determination shows a significative partial deficiency in the liver and a total deficiency in the brain. Glycine synthase affinity for glycine is similar for controls and patients and this lead use to think that the deficiency is due to a diminished biosynthesis of the enzyme molecule.

Amino Acid Metabolism, Inborn Errors↗