Biomedical subjects

T Lehmann

Publications and source records attributed to T Lehmann.

At least 19 recordsLinked to original sources

PubMed2004

Revisiting the role of introgression vs shared ancestral polymorphisms as key processes shaping genetic diversity in the recently separated sibling species of the Anopheles gambiae complex.

The role of interspecific hybridisation in the evolution of pest species is poorly understood. In mosquito disease vectors this is of particular importance due to the evolution of insecticide resistance and the proposed release of transgenic strains that are refractory to the malaria parasite. In this study, we apply population genetic methods in a novel manner to determine whether mitochondrial DNA sequences have introgressed between the closely related African malaria vectors Anopheles gambiae and A. arabiensis. Our results suggest that speciation was geologically recent and ancestral haplotypes at the ND5 locus are retained in both species. In addition, comparing haplotype frequencies in allopatric and sympatric populations, suggest locale specific unidirectional introgression of mitochondria from A. arabiensis into A. gambiae.

Africa↗

PubMed2003

Characterization of Toxoplasma gondii isolates from free range chickens from Paraná, Brazil.

The prevalence of Toxoplasma gondii in free range chickens is a good indicator of the prevalence of T. gondii oocysts in the environment because chickens feed from the ground. In the present study, prevalence of T. gondii in 40 free range chickens (Gallus domesticus) from a rural area surrounding Paraná, Brazil was assessed. Blood, heart, and brain from each chicken were examined for T. gondii infection. Antibodies to T. gondii, assayed with the modified agglutination test (MAT> or =1:5) were found in 16 chickens. Hearts and brains of seropositive (MAT> or =1:5) chickens were bioassayed in mice. Additionally, hearts and brains of seronegative (MAT<1:5) chickens were bioassayed in two T. gondii-free cats (12 chickens per cat). T. gondii was isolated from 13 of 16 (81%) seropositive chickens. Of the two cats fed tissues pooled form seronegative chickens, one shed T. gondii oocysts. Nine of the 13 T. gondii isolates killed 100% of infected mice. The T. gondii isolate from the cat was also virulent for mice. Genotyping of 13 chicken isolates of T. gondii using the SAG2 locus indicated that seven isolates were type I and six were type III; three of these type III isolates killed all infected mice suggesting that all strains virulent for mice are not type I. The isolate from the feces of the cat fed chicken tissues was type I.

Agglutination Tests↗

PubMed2003

Semipermeable species boundaries between Anopheles gambiae and Anopheles arabiensis: evidence from multilocus DNA sequence variation.

Attempts to reconstruct the phylogenetic history of the Anopheles gambiae cryptic species complex have yielded strongly conflicting results. In particular, An. gambiae, the primary African malaria vector, is variously placed as a sister taxon to either Anopheles arabiensis or Anopheles merus. The recent divergence times for members of this complex complicate phylogenetic analysis, making it difficult to unambiguously implicate interspecific gene flow, versus retained ancestral polymorphism, as the source of conflict. Using sequences at four unlinked loci, which were determined from multiple specimens within each of five species in the complex, we found contrasting patterns of sequence divergence between the X chromosome and the autosomes. The isolation model of speciation assumes a lack of gene flow between species since their separation. This model could not be rejected for An. gambiae and An. arabiensis, although the data fit the model poorly. On the other hand, evidence from gene trees supports genetic introgression of chromosome 2 inversions between An. gambiae and An. arabiensis, and also points to more broad scale genetic exchange of autosomal sequences between this species pair. That such exchange has been relatively recent is suggested not only by the lack of fixed differences at three autosomal loci but also by the sharing of full haplotypes at two of the three loci, which is in contrast to several fixed differences and considerably deeper divergence on the X. The proposed acquisition by An. gambiae of sequences from the more arid-adapted An. arabiensis may have contributed to the spread and ecological dominance of this malaria vector.

Animals↗

PubMed2003

Isolation and molecular characterization of Toxoplasma gondii from chickens and ducks from Egypt.

The prevalence of Toxoplasma gondii in free range chickens is a good indicator of the prevalence of T. gondii oocysts in the environment because chickens feed from the ground. In the present study, prevalence of T. gondii in 121 free range chickens (Gallus domesticus) and 19 ducks (Anas sp.) from a rural area surrounding Giza, Egypt was assessed. Blood, heart, and brain from each animal were examined for T. gondii infection. Antibodies to T. gondii, assayed with the modified agglutination test (MAT), were found in 49 (40.4%) chickens in titers of 1:5 in 11, 1:10 in four, 1:20 in four, 1:40 in eight, 1:80 in 10, and 1:160 or more in 12 chickens. Antibodies were found in three ducks each with a titer of 1:80. Hearts and brains of seropositive (MAT > or = 1:5) chickens and ducks were bioassayed in mice. Additionally, hearts and brains of seronegative (MAT<1:5) animals were bioassayed in T. gondii-free cats. T. gondii was isolated from 19 of 49 seropositive chickens (one with a titer of 1:5, two with a titer of 1:20, one with a titer of 1:40, five with a titer of 1:80, three with a titer of 1:160, and seven with a titer of > or = 1:360). One cat fed tissues pooled from 15 seronegative chickens shed T. gondii oocysts, while two cats fed tissues of 34 seronegative chickens did not shed oocysts. T. gondii was isolated from one of the seropositive ducks by bioassay in mice. The two cats fed tissues from 16 seronegative ducks did not shed oocysts. Genotyping of 20 chicken isolates of T. gondii using the SAG 2 locus indicated that 17 isolates were type III and three were type II. The duck isolate of T. gondii was type III. The mice inoculated with tissue stages of all 21 isolates of T. gondii from chickens and ducks remained asymptomatic, indicating that phenotypically they were not type I because type I strains are lethal for mice. Infections with mixed genotypes were not found.

Agglutination Tests↗

PubMed2003

Interest of pronostic score for optimal clinical management of obese patients.

OBJECTIVE: The aim of this retrospective study was to identify key factors favoring weight regain. METHODS: Therefore, prognostic factors for weight loss and regain have been retrieved and identified among 186 obese patients (40 +/- 2 y and 34 +/- 0.3 kg/m(2)) through the use of a simple questionnaire which considered psychological issues such as depression, anxiety and the patient's individual capacity to follow a diet. All patients have been prescribed a low-calorie diet (1200 kcal/day) being either balanced, food-combining or low-CHO. Follow-up averaged 6.4 +/- 0.3 months of which weight loss accounted for 4.4 +/- 0.1 months. RESULTS: Weight loss was similar in all 3 groups and averaged 6.0 +/- 0.2 kg. The final weight loss and weight regain results have been identical for the 3 groups. A high/bad prognostic score rating is associated with weight regain (P<0.02). Weight regain is significantly influenced by the initial weight loss speed (P<0.0001). CONCLUSIONS: The proposed prognostic score is likely to be helpful for clinicians better to profile the therapeutic approach to individualized obesity management and follow-up. Diet composition does not influence either weight loss or weight regain.

Adaptation, Psychological↗

PubMed2003

Toxoplasma gondii isolates from free-ranging chickens from the United States.

Prevalence of Toxoplasma gondii infection in chickens is a good indicator of the strains prevalent in their environment because they feed from ground. The prevalence of T. gondii was determined in 118 free-range chickens from 14 counties in Ohio and in 11 chickens from a pig farm in Massachusetts. Toxoplasma gondii antibodies (> or = 1: 5) were found using the modified agglutination test (MAT) in 20 of 118 chickens from Ohio. Viable T. gondii was recovered from 11 of 20 seropositive chickens by bioassay of their hearts and brains into mice. The parasite was not isolated from tissues of 63 seronegative (< or = 1:5) chickens by bioassay in cats. Hearts, brains, and muscles from legs and breast of the 11 chickens from the pig farm in Massachusetts were fed each to a T. gondii-negative cat. Eight cats fed chicken tissues shed oocysts; the 3 cats that did not shed oocysts were fed tissues of chickens with MAT titers of 1:5 or less. Tachyzoites of 19 isolates of T. gondii from Ohio and Massachusetts were considered avirulent for mice. Of 19 isolates genotyped, 5 isolates were type II and 14 were type III; mixed types and type I isolates were not found.

Agglutination Tests↗

PubMed2003

Isolation and genotyping of Toxoplasma gondii from free-ranging chickens from Argentina.

The prevalence of Toxoplasma gondii in free-ranging chickens can be considered a good indicator of the prevalence of T. gondii oocysts in the environment because chickens feed from the ground. In the present study, prevalence of T. gondii in 29 free-range chickens (Gallus domesticus) from Argentina was investigated. Blood, heart, and brain from each chicken were examined for T. gondii infection. Antibodies to T. gondii, assayed with the modified agglutination test (MAT), were found in 19 of 29 (65.5%) chickens. Hearts and brains of seropositive (MAT > or = 1:5) chickens were bioassayed in mice. Toxoplasma gondii was isolated from 9 of 19 seropositive chickens. Genotyping of chicken isolates of T. gondii using the SAG2 locus indicated that 1 was type I, 1 was type II, and 7 were type III. This is the first report of isolation of T. gondii from chickens from Argentina.

Agglutination Tests↗

PubMed2003

Toxoplasma gondii isolates of free-ranging chickens from Rio de Janeiro, Brazil: mouse mortality, genotype, and oocyst shedding by cats.

Most isolates of Toxoplasma gondii can be grouped into 3 genetic lineages. In the present study, 67 isolates of T. gondii were obtained by bioassay in mice inoculated with brains and hearts of 96 asymptomatic chickens from an area highly endemic to human infection in Rio de Janeiro, Brazil. Of the 48 isolates genotyped using the SAG2 locus, 34 (70%) were of type I and 13 (27%) were of type III. No isolate of type II was recovered. Isolates from 1 chicken contained a type I and type III mixed infection, indicating natural multiparasite infection in the same animal. Cats fed mice infected with 11 type I strains shed 19-535 million oocysts in their feces, indicating that type I isolates can circulate in the environment.

Animals↗

PubMed2002

Biological and genetic characterisation of Toxoplasma gondii isolates from chickens (Gallus domesticus) from São Paulo, Brazil: unexpected findings.

In spite of a wide host range and a world wide distribution, Toxoplasma gondii has a low genetic diversity. Most isolates of T. gondii can be grouped into two to three lineages. Type I strains are considered highly virulent in outbred laboratory mice, and have been isolated predominantly from clinical cases of human toxoplasmosis whereas types II and III strains are considered avirulent for mice. In the present study, 17 of 25 of the T. gondii isolates obtained from asymptomatic chickens from rural areas surrounding São Paulo, Brazil were type I. Antibodies to T. gondii were measured in 82 chicken sera by the modified agglutination test using whole formalin-preserved tachyzoites and mercaptoethanol and titres of 1:10 or more were found in 32 chickens. Twenty-two isolates of T. gondii were obtained by bioassay in mice inoculated with brains and hearts of 29 seropositive (> or =1:40) chickens and three isolates were obtained from the faeces of cats fed tissues from 52 chickens with no or low levels (<1:40) of antibodies. In total, 25 isolates of T. gondii were obtained by bioassay of 82 chicken tissues into mice and cats. All type I isolates killed all infected mice within 4 weeks whereas type III isolates were less virulent to mice. There were no type II strains. Tissue cysts were found in mice infected with all 25 isolates and all nine type I isolates produced oocysts. Infected chickens were from localities that were 18-200 km apart, indicating no common source for T. gondii isolates. This is the first report of isolation of predominantly type I strains of T. gondii from a food animal. Epidemiological implications of these findings are discussed.

Agglutination Tests↗

PubMed2002

Factors influencing energy intake and body weight loss after gastric bypass.

OBJECTIVE: The gastric bypass-induced quantitative and qualitative modifications of energy intake (En In, kcal/day) and their impact on body weight (bw) loss were evaluated. The factors influencing energy intake and body weight loss were also investigated. DESIGN: Longitudinal study. SETTING: University Hospital of Geneva. SUBJECTS: Fifty obese women undergoing a Roux-en-Y gastric bypass. RESULTS: The reduction of EnIn was significantly related to bw loss expressed either in kg or as percentage correction of excess bw (P<0.01 for both), whereas the post-operative modifications of diet composition did not play a role. Age and initial bw significantly influenced bw loss (P<0.0001 and P<0.001, respectively), as shown by multiple regression analysis. Patients were divided into four sub-groups according to their age (under or over 35 y) and initial bw (under or over 120 kg). ANOVA showed that under 35-y-old subjects reduced their EnIn significantly more than their older counterparts having similar bw (P<0.02 and P<0.05); consequently, bw loss, expressed in kg, was significantly (P<0.0001 and P<0.0005) larger in younger patients. Subjects with an initial bw over 120 kg lost significantly (P<0.001 and P<0.02) more weight as compared to patients with a smaller degree of obesity (under 120 kg) and similar age. CONCLUSIONS: Gastric bypass-induced body weight loss is mainly due to the reduction of EnIn, whereas the qualitative modifications of the diet do not play a role. Younger subjects have a greater capacity to reduce EnIn and, therefore, lose more weight. Pre-operative high degree of obesity leads to a larger weight reduction, probably because of a greater energy deficit.

Adult↗

PubMed2002

Mesenteric inflammatory veno-occlusive disease: a rare cause of intestinal ischemia. The first description of recurrent disease.

BACKGROUND: Mesenteric inflammatory veno-occlusive disease (MIVOD) is a rare cause of intestinal ischemia of unknown etiology. Histologically, MIVOD is characterized by extended thrombophlebitis and fibrous organized thrombosis of multiple veins. The arteries are by definition not involved. Management includes surgery in all cases described. Recurrence has not been described until now. METHODS: We describe the case of a 64-year-old woman operated with the suspicion of intestinal ischemia. Clinical and histopathological characteristics are reported. RESULTS: The patient underwent a right hemicolectomy and segmental resection of the terminal ileum 15 months later for a recurrence. The histological examination of the resected specimen confirmed the diagnosis of MIVOD and a recurrence thereof. CONCLUSION: MIVOD is a rare cause of colonic ischemia. Recurrence of the disease, which is described here for the first time, is unusual after surgical resection.

Colitis, Ischemic↗

PubMed2002

Acarbose improves indirectly both insulin resistance and secretion in obese type 2 diabetic patients.

BACKGROUND: Acarbose is an oral antidiabetic mainly acting on postprandial blood glucose, inhibiting alphaglucosidase. Through this mechanism, it could improve the peripheral insulin sensitivity and/or increase the insulin secretion. The aim of the present study is to assess the therapeutic efficacy of Acarbose in obese type 2 diabetic patients on both insulin resistance and insulin secretion. METHODS: 17 obese non insulin-dependent diabetic patients, well controlled with diet alone were randomized into 2 groups: acarbose (2 x 50 mg) or placebo during 16 weeks. A glucagon test allowed to evaluate insulin secretion before and after treatment as well as a triple test (glucose-insulin-somatostatin) with indirect calorimetry allowed to evaluate insulin sensitivity. RESULTS: A significant improvement in post-prandial plasma glucose was detected only in the Acarbose group (8.0 +/- 0.5 mmol/l before vs 6.5 0.5 mmol/l after, p<0.05). Basal C-peptide secretion was similar between groups and remained unchanged after treatment. However, stimulated insulin secretion was significantly increased by 30%, p<0.05, in the Acarbose group while no change was detected in the placebo group. Interestingly, the group receiving Acarbose disclosed a 15% reduction in insulin resistance (15.0 +/- 1.8 mmol/l before vs 12.8 +/- 1.4 mmol/l after). CONCLUSIONS: Our results show that a treatment with Acarbose is efficient even in diabetic patients presenting a good glucose control without any other associated treatment. By decreasing post-prandial blood glucose, acarbose improves both insulin sensitivity and secretion.

Acarbose↗

PubMed2001

Toward a novel metal-based chemotherapy against tropical diseases. 6. Synthesis and characterization of new copper(II) and gold(I) clotrimazole and ketoconazole complexes and evaluation of their activity against Trypanosoma cruzi.

The complexes [Cu(CTZ)(4)]Cl(2).2H(2)O (1), [Cu(CTZ)Cl(2)](2) (2), [Cu(KTZ)(3)Cl(2)] (3), and [Cu(KTZ)Cl(2)](2).2H(2)O (4) were prepared by reaction of CuCl(2) with CTZ and KTZ (where CTZ = 1-[[(2-chlorophenyl)diphenyl]methyl]-1H-imidazole and KTZ = cis-1-acetyl-4-[4-[[2-(2,4-dichlorophenyl)-2-(1H-imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]methoxy]phenyl]piperazine), respectively, in acetonitrile at different ligand to metal molar ratios. Gold complexes [Au(PPh(3))(CTZ)]PF(6) (5) and [Au(PPh(3))(KTZ)]PF(6).H(2)O (6) were synthesized by reaction of AuClPPh(3), with KPF(6) and CTZ or KTZ in acetonitrile. All the new compounds were characterized by NMR spectroscopy and microanalytical methods, and for the paramagnetic species EPR spectroscopy and DC magnetic susceptibility measurements were also employed. The solid-state structure of 1 has been determined by X-ray crystallography. 1 crystallizes in the triclinic space group P(-)1, with a = 12.773(2) A, b = 15.326(4) A, c = 11.641(2) A, V = 1957.4(7) A(3), Z = 1, and D(calcd) = 1.284 g/cm(3). The structure refinement converged at R1 = 0.0731 and wR2 = 0.1962. Complex 1 displayed a square-planar structure typical for tetrakis(imidazole)copper(II) complexes. The new compounds were tested for in vitro activity against cultures of epimastigotes of Trypanosoma cruzi, the causative agent of Chagas disease. At concentrations equivalent to 10(-6) M of total CTZ or KTZ (in DMSO) all the complexes exhibited significantly higher growth inhibitory activity than their respective parental compounds.

Algorithms↗

PubMed2001

[Chlamydia pneumoniae: an cause of reactive arthritis?].

Chlamydia pneumoniae is a common cause of acute infections within the upper respiratory tract. It is less well known that chlamydia pneumoniae, just like chlamydia trachomatis, may also trigger reactive arthritis. We describe three patients with arthritis possibly triggered by chlamydia pneumoniae. The patients showed the typical symptoms of reactive arthritis like asymmetric oligo- or polyarthritis, dactylitis, enthesiopathies and tendovaginitis. The course of the disease was quite different. The first patient developed persistent polyarthritis which required longterm treatment with a rheumatic disease modifying drug; the second patient improved after several weeks and the third patient experienced a full remission within a few days.

Acute Disease↗

PubMed2001

Dopaminergic 7-aminotetrahydroindolizines: ex-chiral pool synthesis and preferential D3 receptor binding.

Starting from both isomers of enantiopure asparagine, heterocyclic bioisosteres of the preferential dopamine D3 receptor agonist (R)-7-OH-DPAT were investigated when SAR studies led to the 3-formyl substituted aminoindolizine (S)-1e (FAUC 54) displaying a K(i) value of 6.0 nM for the high affinity D3 binding site. In contrast, D3 affinity of the enantiomer (R)-1e was 300 fold lower.

Animals↗

PubMed2001

Expression of MRP1 and related transporters in human lung cells in culture.

Multidrug resistance type 1 P-glycoproteins (P-gp) and multidrug resistance associated proteins (MRP) were studied in differentiated primary human lung cells in culture, in comparison with permanent human lung cell lines and primary alveolar type II cells from rat lung. AII cells exhibited low basal levels of mdr1b mRNA, that increased over time and after oxygen radical production induced by paraquat. mRNAs coding for antioxidative enzymes catalase (CAT), maganese superoxide dismutase (Mn-SOD) and copper/zinc superoxide dismutase (Cu/Zn-SOD) were not changed. H358, A549, H322 cells expressed low levels of MDR1 mRNA, but the mdr1 substrate rhodamine 123 (Rh 123) was transported out of H358 and H322 cells in a non-invasive, single cell fluorescence assay. The dye efflux could be inhibited by the chemosensitizer, verapamil. Normal human bronchial epithelial cells (NHBEC) expressed immuno-reactive MDR1 P-gp and the MPR protein that was active in the fluorescence assay using the MRP substrate carboxy-dichlorofluorescein (CDF) and MK-571 as an inhibitor. We did observe inter-individual variation of MRP in both the mRNA and the immunoreactive protein in NHBEC culture. Over time (12 weeks) the protein was relatively stable in NHBEC and epithelial cells from peripheral lung (PLC), but the mRNA level was drastically increased when explant cultures were continued (18 weeks).

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2001

Catalysis of dehydrogenation of 4-trans-(N,N-dimethylamino)cinnamaldehyde by aldehyde dehydrogenase.

4-trans-(N,N-dimethylamino)cinnamaldehyde (DACA) is a chromophoric and fluorogenic substrate of aldehyde dehydrogenase. Fluorescence of DACA is enhanced by binding to aldehyde dehydrogenase in the absence of catalysis both in the presence and absence of the coenzyme analogue 5'AMP. DACA binds to aldehyde dehydrogenase with a dissociation constant of 1-3 microM and stoichiometry of 2 mol mol(-1) enzyme. Incorporation of DACA during catalysis was also investigated and found to be 2 mol DACA mol(-1) enzyme. Effect of pH on the stoichiometry of DACA incorporation during catalysis has shown that DACA incorporation remained constant at 2 mol DACA mol(-1) enzyme, despite a 74-fold velocity enhancement between pH 5.0 and 9.0. Increase of pH increased decomposition of enzyme-acyl intermediate without affecting the rate-limiting step of the reaction. At pH 7.0 the pH stimulated velocity enhancement was 10-fold over that at pH 5.0; further velocity enhancement (11.5-fold that of pH 7.0) was achieved by 150 microM Mg(2+) ions. The velocity at pH 7.0 with Mg(2+) exceeded that of pH 9.0, and that at maximal pH stimulation at pH 9.5. It was observed that level of intermediate decreased to about 1 mol mol(-1) enzyme, indicating that Mg(2+) ions increased the rate of decomposition of the enzyme-acyl intermediate and shifted the rate-limiting step of the reaction to another step in the reaction sequence.

Aldehyde Dehydrogenase↗

PubMed2001

Speciation and population structure in the morphospecies Lutzomyia longipalpis (Lutz & Neiva) as derived from the mitochondrial ND4 gene.

Recent studies have suggested that the phlebotomine sand fly Lutzomyia longipalpis (Diptera: Psychodidae), the principal vector of visceral leishmaniasis in the Neotropics, may consist of several allopatric sibling species. Phylogenetic and population genetic analyses of nucleotide variation in a 618-bp fragment of the mitochondrial ND4 gene were carried out on specimens of Lu. longipalpis from several locations in Central and South America. The analyses were concordant with previous findings, indicating that certain allopatric populations of Lu. longipalpis have become sufficiently differentiated as to represent sibling species. Phylogenetic analyses revealed deep genetic divisions between four clades represented by specimens from northern South America, Brazil, Central America, and an isolated Colombian population. Strong differentiation also was observed between certain populations within the first two clades. Partitioning of genetic diversity within and between Central American populations did not show the presence of more than one species in the region. However, distance, even within the 70-km range of the Honduran collection sites, was found to have a remarkably strong effect on gene flow. The highly subdivided population structure may be due to the patchiness of their distribution. F(ST) values comparing a Guatemalan population with several Honduran populations revealed a level of differentiation associated with a negligible rate of gene flow.

Alleles↗