Cospeciation between bacterial endosymbionts (Buchnera) and a recent radiation of aphids (Uroleucon) and pitfalls of testing for phylogenetic congruence.

Previous studies of phylogenetic congruence between aphids and their symbiotic bacteria (Buchnera) supported long-term vertical transmission of symbionts. However, those studies were based on distantly related aphids and would not have revealed horizontal transfer of symbionts among closely related hosts. Aphid species of the genus Uroleucon are closely related phylogenetically and overlap in geographic ranges, habitats, and parasitoids.

Precise binding of single-stranded DNA termini by human RAD52 protein.

The human RAD52 protein, which exhibits a heptameric ring structure, has been shown to bind resected double strand breaks (DSBs), consistent with an early role in meiotic recombination and DSB repair. In this work, we show that RAD52 binds single-stranded and tailed duplex DNA molecules via precise interactions with the terminal base. When probed with hydroxyl radicals, ssDNA-RAD52 complexes exhibit a four-nucleotide repeat hypersensitivity pattern.

Cospeciation of psyllids and their primary prokaryotic endosymbionts.

Psyllids are plant sap-feeding insects that harbor prokaryotic endosymbionts in specialized cells within the body cavity. Four-kilobase DNA fragments containing 16S and 23S ribosomal DNA (rDNA) were amplified from the primary (P) endosymbiont of 32 species of psyllids representing three psyllid families and eight subfamilies. In addition, 0.

Marked increase of venlafaxine enantiomer concentrations as a consequence of metabolic interactions: a case report.

On three occasions, unusually high trough plasma concentrations of venlafaxine were measured in a patient phenotyped and genotyped as being an extensive CYP2D6 metabolizer and receiving 450 mg/day of venlafaxine and multiple comedications. Values of 1.54 and of 0.

Bacterial endosymbionts in animals.

Molecular phylogenetic studies reveal that many endosymbioses between bacteria and invertebrate hosts result from ancient infections followed by strict vertical transmission within host lineages. Endosymbionts display a distinctive constellation of genetic properties including AT-biased base composition, accelerated sequence evolution, and, at least sometimes, small genome size; these features suggest increased genetic drift. Molecular genetic characterization also has revealed adaptive, host-beneficial traits such as amplification of genes underlying nutrient provision.

Sulfonylurea receptor ligands modulate stretch-induced ANF secretion in rat atrial myocyte culture.

Stretch-induced atrial natriuretic factor (ANF) secretion was studied in cultures of neonate atrial appendage myocytes. Stretch, applied for 40 min by hypotonic swelling, increased the mean area of 44 individually imaged myocytes by 4.8-8.

Analysis of telomerase catalytic subunit mutants in vivo and in vitro in Schizosaccharomycespombe.

The chromosome end-replicating enzyme telomerase is composed of a template-containing RNA subunit, a reverse transcriptase (TERT), and additional proteins. The importance of conserved amino acid residues in Trt1p, the TERT of Schizosaccharomyces pombe, was tested. Mutation to alanine of the proposed catalytic aspartates in reverse transcriptase motifs A and C and of conserved amino acids in motifs 1 and B' resulted in defective growth, progressive loss of telomeric DNA, and loss of detectable telomerase enzymatic activity in vitro.

Thromboembolic complications associated with reproductive endocrinologic procedures.

Thromboembolism as a complication of hormonal ovarian stimulation in the context of artificial reproductive techniques is rare and seems to occur when OHS is present. Although accompanied by high serum estrogen concentrations, hCG seems to play a central role in the development of OHS, which has been observed in women with 17,18-desmolase deficiency who have low estrogen levels after induction of ovulation with hGC. Although there is some evidence that hormonal ovarian stimulation with HMG, leading to elevated estrogen levels, and ovulation induction with hCG in preparation for in vitro fertilization are associated with a state of hypercoagulability, the exact role of estrogens, hCG and the physicochemical changes (fluid shift into third spaces) involved in OHS remain to be elucidated.

Steady state plasma levels of the enantiomers of trimipramine and of its metabolites in CYP2D6-, CYP2C19- and CYP3A4/5-phenotyped patients.

Steady state plasma concentrations of the (L)- and (D)-enantiomers of trimipramine (TRI), desmethyltrimipramine (DTRI), 2-hydroxytrimipramine (TRIOH) and 2-hydroxydesmethyl-trimipramine (DTRIOH) were measured in 27 patients receiving between 300 and 400 mg/day racemic TRI. The patients were phenotyped with dextromethorphan and mephenytoin, and the 8-hour urinary ratios of dextromethorphan/dextrorphan, dextromethorphan/3-methoxymorphinan, and (S)-mephenytoin/(R)mephenytoin were used as markers of cytochrome P-450IID6 (CYP2D6), CYP3A4/5 and CYP2C19 activities, respectively. One patient was a CYP2D6 and one was a CYP2C19 poor metabolizer.

Cytochrome P-450 activities in human and rat brain microsomes.

The role of cytochrome P450 in the metabolism of dextromethorphan, amitriptyline, midazolam, S-mephenytoin, citalopram, fluoxetine and sertraline was investigated in rat and human brain microsomes. Depending on the parameters, the limit of quantification using gas chromatography-mass spectrometry methods was between 1.6 and 20 pmol per incubation, which generally contained 1500 microg protein.

Sequence evolution in bacterial endosymbionts having extreme base compositions.

A major limitation on ability to reconstruct bacterial evolution is the lack of dated ancestors that might be used to evaluate and calibrate molecular clocks. Vertically transmitted symbionts that have cospeciated with animal hosts offer a firm basis for calibrating sequence evolution in bacteria, since fossils of the hosts can be used to date divergence events. Sequences for a functionally diverse set of genes have been obtained for bacterial endosymbionts (Buchnera) from two pairs of aphid host species, each pair diverging 50-70 MYA.

Heteroduplex formation by human Rad51 protein: effects of DNA end-structure, hRP-A and hRad52.

Purified human Rad51 protein (hRad51) catalyses ATP-dependent homologous pairing and strand transfer reactions, characteristic of a central role in homologous recombination and double-strand break repair. Using single-stranded circular and partially homologous linear duplex DNA, we found that the length of heteroduplex DNA formed by hRad51 was limited to approximately 1.3 kb, significantly less than that observed with Escherichia coli RecA and Saccharomyces cerevisiae Rad51 protein.

Founder mutations and the high prevalence of myotonia congenita in northern Finland.

Objective And Background: To find an explanation at the molecular level for the high prevalence of myotonia congenita in northern Finland and the exceptional pattern of inheritance of the disease in many families, and to study genotype-phenotype correlation in the patients.

Methods: Forty-six patients with myotonia congenita and 16 unaffected relatives from 24 families were studied. All 23 exons and their flanking regions of the gene for the chloride channel protein (ClC-1) were sequenced from at least one patient from all families.

Venous Doppler in the sonographic surveillance of fetuses with supraventricular tachycardia.

Objective: In animals and adult humans sustained supraventricular tachycardia leads to myocardial remodelling and dysfunction, persisting even after drug-induced cardioversion to sinus rhythm. This study was undertaken, to evaluate cardiac function in the human fetus by noninvasive determination of the degree of AV valve incompetence and venous blood flow, in order to enhance understanding of the pathophysiology of fetal supraventricular tachycardia. Furthermore, we wanted to determine the usefulness of these methods in the surveillance of these fetuses before and after drug-induced cardioversion.

Transport mechanisms for the antidepressant citalopram in brain microvessel endothelium.

Blood-brain barrier transport of the selective serotonin reuptake inhibitor and antidepressant, citalopram, was studied using monolayers of bovine brain microvessel endothelial cells (BMECs). This study provides for the first time, evidence of a transport mechanism for a selective serotonin reuptake inhibitor (SSRI). Carrier-mediated transport, efflux mechanisms, as well as inhibition of metabolizing enzymes of citalopram were investigated.

Oral and intravenous methadone use: some clinical and pharmacokinetic aspects.

A sample of 15 patients participating in an injectable methadone trial and of 15 patients in an oral methadone maintenance treatment, who admitted injecting part or all of their methadone take-home doses, were compared to 20 patients in maintenance treatment who use methadone exclusively by mouth. The present study confirms the poorer general health, the higher levels of emotional, psychological or psychiatric problems, the higher use of illicit drugs, and the higher number of problems related to employment and support associated with the use of the intravenous mode of administration of methadone. As expected, due to the shunt of metabolism in the gut wall and of the liver first-pass effect, higher concentration to dose ratios of (R)-methadone, which is the active enantiomer, were measured in the intravenous group (23% increase).

Pharmacokinetic consequences of a citalopram treatment discontinuation.

In this pilot study, the pharmacokinetics of citalopram (CIT) were examined in five hospitalized depressed patients after an abrupt discontinuation of a treatment with 40 mg/d of this selective serotonin reuptake inhibitor (SSRI). During the 8-day study period, clinical ratings were regularly carried out. Between days 5 and 8, the patients were treated with clomipramine (75 mg/d).

Effects of carbamazepine coadministration on plasma concentrations of the enantiomers of mianserin and of its metabolites.

Concentrations of the enantiomers of unconjugated and of total (unconjugated plus conjugated) mianserin, desmethylmianserin and 8-hydroxymianserin were measured in 12 patients before and after the introduction of carbamazepine. The dose of mianserin was 60 mg/d, carbamazepine was coadministered at 400 mg/d for 4 weeks, and blood samples were taken at weekly intervals after the introduction of carbamazepine. Each week, carbamazepine significantly decreased plasma concentrations of unconjugated and total (S)-mianserin (the more potent enantiomer) and of unconjugated and total (R)-mianserin.