Avirulence of rough mutants of Shigella flexneri: requirement of O antigen for correct unipolar localization of IcsA in the bacterial outer membrane.

Mutations in the lipopolysaccharide (LPS) of Shigella spp. result in attenuation of the bacteria in both in vitro and in vivo models of virulence, although the precise block in pathogenesis is not known. We isolated defined mutations in two genes, galU and rfe, which directly affect synthesis of the LPS of S. flexneri 2a, in order to determine more precisely the step in virulence at which LPS mutants are blocked. The galU and rfe mutants invaded HeLa cells but failed to generate the membrane protrusions (fireworks) characteristic of intracellular motility displayed by wild-type shigellae. Furthermore, the galU mutant was unable to form plaques on a confluent monolayer of eucaryotic cells and the rfe mutant generated only tiny plaques. These observations indicated that the mutants were blocked in their ability to spread from cell to cell. Western immunoblot analysis of expression of IcsA, the protein essential for intracellular motility and intercellular spread, demonstrated that both mutants synthesized IcsA, although they secreted less of the protein to the extracellular medium than did the wild-type parent. More strikingly, the LPS mutants showed aberrant surface localization of IcsA. Unlike the unipolar localization of IcsA seen in the wild-type parent, the galU mutant expressed the protein in a circumferential fashion. The rfe mutant had an intermediate phenotype in that it displayed some localization of IcsA at one pole while also showing diffuse localization around the bacterium. Given the known structures of the LPS of wild-type S. flexneri 2a, the rfe mutant, and the galU mutant, we hypothesize that the core and O-antigen components of LPS are critical elements in the correct unipolar localization of IcsA. These observations indicate a more precise role for LPS in Shigella pathogenesis.     

Gender differences and diabetic status in the relationship of blood apolipoprotein C-III, free fatty acids and triglycerides in subjects at risk for glucose intolerance

Insulin resistance and hyperinsulinemia can induce overproduction of triglyceride (TG) rich VLDL in the liver by increasing the availability of free fatty acids (FFA). Conversely, apolipoprotein C-III (apoC-III) is an inhibitor of the catabolism of TG-rich lipoproteins. To explore the relationship among FFA, apo C-III and TG in hyperinsulinemic subjects, we studied 103 individuals (63 women and 40 men) with a body mass index (BMI) 25 Kg/m2: 59 subjects with normal glucose tolerance (NGT), and 44 with newly diagnosed type 2 diabetes. After adjustment for age, BMI, fasting insulin and TG, FFA were significantly higher in women than in men and in subjects with diabetes compared with NGT. Subjects with diabetes had higher apo C-III levels compared to NGT, adjusted for age, sex and BMI, and that was largely accounted for by differences in insulin and TG levels. In addition, regression analysis in subjects with diabetes showed that TG were strongly associated with apo C-III in both men and women (r = 0.90 and 0.79, respectively; p < 0.001), while the association tended to be smaller between TG and FFA (r = 0.48, p < 0.05 in men and r = 0.45, p = 0.06 in women). Conversely, in individuals with NGT fasting TG was strongly associated with apo C-III in men (r = 0.83, p < 0.01) but not with FFA, while in women TG was associated with FFA (r = 0.39, p < 0.05) but not with apo C-III. In summary, elevated apo C-III was a predominant factor associated with elevated TG levels in NGT men and all subjects with type 2 diabetes, while FFA were more closely related with TG levels in NGT women.     

Heat Shock Protein 70 of the Agent of Human Granulocytic Ehrlichiosis Binds to Borrelia burgdorferi Antibodies

We describe a patient with human granulocytic ehrlichiosis (HGE), a diagnosis confirmed by PCR and immunoblot analysis. Unexpectedly, immunoglobulin G (IgG) directed towards an 80-kDa ehrlichial antigen (without detectable IgM) was present in the patient’s serum in the first week of illness. Lyme disease immunoblots were reactive for IgG (but not IgM), a result indicative of prior exposure to the Lyme disease spirochete. Amino-terminal sequencing revealed that the 80-kDa ehrlichial antigen was an HSP-70 homolog similar to Borrelia burgdorferi HSP-70. We conclude that antibodies against B. burgdorferi HSP-70 may cross-react with the ehrlichial heat shock protein and that this possibility must be considered when serologic test results for HGE and Lyme disease are interpreted.     

Cloning and expression of the major 47-kilodalton surface immunogen of Treponema pallidum in Escherichia coli.

Monoclonal antibodies directed against the 47-kilodalton (kDa) major outer membrane surface immunogen of virulent Treponema pallidum subsp. pallidum were used to select Escherichia coli recombinant clones expressing the 47-kDa immunogen. The phenotype of the clones was dependent on the presence of recombinant plasmid in the host cell. Southern hybridization revealed that the cloned T. pallidum subsp. pallidum DNA sequence was an accurate representation of the T. pallidum subsp. pallidum genomic DNA arrangement. Purified immunoglobulin G from rabbits experimentally infected with T. pallidum subsp. pallidum and human secondary syphilitic sera specifically reacted with the clones, while normal human serum or immunoglobulin G from normal rabbit serum did not. Results of Southern hybridization indicated that a homologous 47-kDa immunogen gene was absent in at least four species of nonpathogenic treponemes tested, as well as from total rabbit genomic DNA. Rabbit anti-T. phagedenis biotype Reiter (treponemal nonpathogen) antiserum and a monoclonal antibody directed against a common treponemal determinant were unreactive with the clones. Western blotting and radioimmunoprecipitation experiments with specific monoclonal antibodies revealed that the recombinant (E. coli) and native (T. pallidum subsp. pallidum) forms of the antigen had identical electrophoretic mobilities. The availability of recombinant 47-kDa immunogen provides a new opportunity for biochemical analysis of the protein, structure-function studies, examination of its role in microbial pathogenesis, and assessment of its diagnostic and vaccinogenic potentials.     

Prenatal diagnosis and characterization of an unbalanced whole arm translocation resulting in monosomy for 18p

Monosomy for the short arm of chromosome 18 is one of the most frequent autosomal deletions observed. While most cases result from terminal deletion of 18p, 16% of cases reported were as a result of an unbalanced whole arm translocation resulting in monosomy 18p. The origin and structure of these derivative chromosomes were reported in only a few cases. We report the prenatal diagnosis and characterization of a new case of monosomy 18p as a result of an unbalanced whole arm translocation. Amniocentesis was performed at 15 weeks of gestation on a 34-year-old woman initially referred for advanced maternal age. Holoprosencephaly was identified by ultrasound at the time of amniocentesis. Karyotype analysis showed an unbalanced whole arm translocation between the long arm of one chromosome 18 and the long arm of one chromosome 22, 45,XX,der(18;22)(q10;q10), in all metaphases. In effect, the fetus had monosomy for 18p. Parental karyotypes were normal, suggesting a de novo origin for the der(18;22). Fluorescence in situ hybridization (FISH) analysis was performed with alpha-satellite probes D18Z1 and D14Z1/D22Z1 to identify the origin of the centromere on the der(18;22). Signal was observed with both probes, indicating that the centromere was composed of alpha-satellite DNA from both constituent chromosomes. Genotyping of the fetus and her parents with chromosome 18p STS marker D18S391 showed only the paternal 187 bp allele was present in the fetus, indicating that it was the maternal chromosome 18 involved in the der(18;22). This case and previous reports show that de novo unbalanced whole arm translocations are more likely to retain alpha-satellite sequences from the two chromosomes involved.     

New classification for mental disorders with management guidelines for use in primary care: ICD-10 PHC chapter five.

A primary care version of the International classification of diseases (10th revision) chapter five for mental and behavioural disorders (ICD-10 PHC chapter five) has been developed. This provisional version focuses on 24 conditions which are frequently seen in primary care and which can be managed effectively by general practitioners. The classification is accompanied by a flipcard for each of the conditions. The cards have diagnostic guidelines on one side and management guidelines on the other. The latter provide information which should be given to the patient, advice on the content of counselling, the available treatment methods, and indications for specialist referral. This classification system is also supported by diagnostic decision making aids, medication cards, and patient leaflets to facilitate the recognition and management of patients with mental disorders in primary care settings. The draft version of ICD-10 PHC chapter five will be finalized after field trials which will test the applicability and usefulness of the system in different primary care settings in various countries.     

Autologous mixed lymphocyte reaction in man. XIV. Deficiency of the autologous mixed lymphocyte reaction in acquired immune deficiency syndrome (AIDS) and AIDS related complex (ARC). In vitro effect of purified interleukin-1 and interleukin-2.

Peripheral blood mononuclear cells from male homosexuals with acquired immune deficiency syndrome (AIDS) and with AIDS related complex (ARC) were examined for the autologous mixed lymphocyte reaction (AMLR) between responder T and irradiated autologous non-T cells and in vitro influence of purified human interleukin-1 (IL-1) and -2 (IL-2) on the AMLR. The AMLR was significantly (P less than 0.001) deficient in both ARC and AIDS; the deficiency of the AMLR was of the similar magnitude in two groups when compared to asymptomatic homosexuals and healthy heterosexuals. In vitro addition of IL-2 enhanced the AMLR to the baseline levels of control subjects in most patients in ARC group (P less than 0.01) and in four of 15 patients in AIDS group (P less than 0.01). Addition of IL-1 to IL-2 containing cultures resulted in no further increase in the AMLR response over those with IL-2 alone. This study demonstrates deficiency of the AMLR in patients with ARC and AIDS that is corrected by purified IL-2 in the majority of cases with ARC but only a subset of patients with AIDS. The significance of these findings is discussed.     

软骨组织工程中力学因素的影响及应用

力学因素是软骨组织工程中的重要影响因素之一。近年来的研究表明，力学作用可以刺激细胞因子及激素的分泌，改变三维支架上培养的软骨细胞的新陈代谢，从而促进软骨组织的生长与重建。目前已经有诸多关于体外构建软骨组织的报道，但对于其中的力学因素的影响（包括力学因素对软骨细胞增殖的促进及力学刺激的传导机制等）还没有完全认识。就以上几方面做一综述，并简单介绍生物反应器在软骨组织工程中的应用。     

Severe lower limb malformation associated with other deformities and death in infancy in two brothers.

Two brothers with severe and rare lower limb malformations but normal upper limbs are described. Both brothers had glans hypospadias and they died in early infancy. In the first brother the limb malformation was a severe deformity of the right foot which was split and of rockerbottom shape with oligosyndactyly. In the second brother the right limb below the knee was more severely deformed while only the toes were involved in the left limb. Details of the clinical and pathological findings are described. The most likely mode of inheritance of this rare syndrome is autosomal recessive or X-linked recessive with variable expressivity.     

The relationship between depression and aerobic capacity in hemodialysis patients

Depression and a reduction in the performance of pleasant activities have been reported in patients with end-stage renal disease receiving hemodialysis therapy. The purpose of this study was to examine the relationship between depression and the patients' capacity to engage in physical activity. The patients' VO2max, or maximal oxygen consumption, was found to be positively associated with three standardized self-report measures of depression in a sample of 15 patients receiving hemodialysis. The clinical and theoretical implications of this finding are considered.