The microtubule plus-end-tracking protein TACC3 promotes persistent axon outgrowth and mediates responses to axon guidance signals during development

Background

Formation of precise neuronal connections requires proper axon guidance. Microtubules (MTs) of the growth cone provide a critical driving force during navigation of the growing ends of axons. Pioneer MTs and their plus-end tracking proteins (+TIPs) are thought to play integrative roles during this navigation. TACC3 is a + TIP that we have previously implicated in regulating MT dynamics within axons. However, the role of TACC3 in axon guidance has not been previously explored.

Results

Here, we show that TACC3 is required to promote persistent axon outgrowth and prevent spontaneous axon retractions in embryonic Xenopus laevis neurons. We also show that overexpressing TACC3 can counteract the depolymerizing effect of low doses of nocodazole, and that TACC3 interacts with MT polymerase XMAP215 to promote axon outgrowth. Moreover, we demonstrate that manipulation of TACC3 levels interferes with the growth cone response to the axon guidance cue Slit2 ex vivo, and that ablation of TACC3 causes pathfinding defects in axons of developing spinal neurons in vivo.

Conclusion

Together, our results suggest that by mediating MT dynamics, the + TIP TACC3 is involved in axon outgrowth and pathfinding decisions of neurons during embryonic development.

Is Mycoplasma hominis a vaginal pathogen?

OBJECTIVE

To evaluate the role of Mycoplasma hominis as a vaginal pathogen.

DESIGN

Prospective study comprising detailed history, clinical examination, sexually transmitted infection (STI) and bacterial vaginosis screen, vaginal swabs for mycoplasmas and other organisms, follow up of bacterial vaginosis patients, and analysis of results using SPSS package.

SETTING

Genitourinary medicine clinic, Royal Liverpool University Hospital.

PARTICIPANTS

1200 consecutive unselected new patients who had not received an antimicrobial in the preceding 3 weeks, and seen by the principal author, between June 1987 and May 1995.

MAIN OUTCOME MEASURES

Relation of M. hominis isolation rate and colony count to: (a) vaginal symptoms and with the number of polymorphonuclear leucocytes (PMN) per high power field in the Gram stained vaginal smear in patients with a single condition--that is, candidiasis, bacterial vaginosis, genital warts, chlamydial infection, or trichomoniasis, as well as in patients with no genital infection; (b) epidemiological characteristics of bacterial vaginosis.

RESULTS

1568 diagnoses were made (the numbers with single condition are in parenthesis). These included 291 (154) cases of candidiasis, 208 (123) cases of bacterial vaginosis, 240 (93) with genital warts, 140 (42) chlamydial infections, 54 (29) cases of trichomoniasis, and 249 women with no condition requiring treatment. M. hominis was found in the vagina in 341 women, but its isolation rates and colony counts among those with symptoms were not significantly different from those without symptoms in the single condition categories. There was no association between M. hominis and the number of PMN in Gram stained vaginal smears whether M. hominis was present alone or in combination with another single condition. M. hominis had no impact on epidemiological characteristics of bacterial vaginosis.

CONCLUSION

This study shows no evidence that M. hominis is a vaginal pathogen in adults.

Ureaplasma urealyticum and chronic lung disease

Neonatal lower respiratory tract colonisation with mycoplasma organisms was examined for an association with chronic lung disease. Ureaplasma urealyticum colonised 9/70 (13%) infants less than 1500 g. Seven (78%) colonised and 33 (54%) non-colonised infants developed chronic lung disease. Logistic regression analyses revealed early gestation, but not mycoplasma colonisation, was independently associated with chronic lung disease.

Ophthalmia neonatorum in Bangkok: the significance of Chlamydia trachomatis

In a prospective 2-month case-controlled study, 17 cases of neonatal conjunctivitis were diagnosed. A statistically significant association between neonatal conjunctivitis and the presence of Chlamydia trachomatis (five cases) and Staphylococcus aureus (five cases) was shown. No cases of gonococcal conjunctivitis were found, perhaps because of the routine use of silver nitrate (1%) drops. C. trachomatis conjunctivitis could not be diagnosed on clinical grounds, nor was examination of Giemsa-stained conjunctival scrapes sufficiently sensitive to detect all cases. In order to prevent the long-term morbidity of C. trachomatis infection in both mother and child, specific aetiological diagnosis using immunodiagnostic or cultural procedures is required.

Mycoplasma hominis as a respiratory pathogen in X-linked hypogammaglobulinaemia

We report a case of lower respiratory tract infection with Mycoplasma hominis in a patient with X-linked hypogammaglobulinaemia.

In vitro activity of florphenicol

Florphenicol was active at a lower concentration than chloramphenicol against over half of 234 recent clinical bacterial isolates. The majority (98%) of the isolates were inhibited by florphenicol at a concentration of 8 mg/l or less. Florphenicol was particularly effective against chloramphenicol resistant strains of Haemophilus influenzae. Klebsiella aerogenes and Bacteroides spp. Florphenicol was bacteristatic for salmonellae and Escherichia coli but bactericidal for Haemophilus influenzae. Florphenicol was slightly more active than chloramphenicol against Chlamydia trachomatis, Mycoplasma hominis and Mycoplasma pneumoniae but less active against Ureaplasma urealyticum.

Incidence of Ureaplasma urealyticum in endourethral swabs compared with first voided urine from men

The incidence of Ureaplasma urealyticum in endourethral swabs was compared with that in first voided urine specimens from 171 male patients. The organism was isolated from the urethras of 72 (42%) and from the urine of 66 (39%). The interval since last voiding urine did not significantly influence the incidence of infection or ureaplasma counts in either type of specimen. Urethritis was strongly associated with ureaplasma counts of greater than or equal to 5 x 10(5) colour changing units (ccu)/ml in the urethra and greater than or equal to 5 x 10(3) ccu/ml in urine.

Ciprofloxacin treatment of chlamydial infections of urogenital tracts of women

Ciprofloxacin was evaluated in chlamydial infections of the urogenital tracts of women treated with a dosage regimen of 500 mg orally twice a day for seven days. Of the 40 women evaluated, 30 were infected with Chlamydia trachomatis only, two were infected with Neisseria gonorrhoeae only, and a further eight had combined gonococcal and chlamydial infections. Ten were found to be harbouring Chlamydia trachomatis in the urethra as well as the cervix. Neisseria gonorrhoeae was eradicated from all patients with or without concomitant chlamydial infection. The overall chlamydial reisolation rates were 14% (5/35) four weeks after treatment and 23% (6/26) 11 weeks after treatment. The organism was not reisolated from the urethra of any of the patients after treatment. Ciprofloxacin was effective against Mycoplasma hominis, but almost completely ineffective against Ureaplasma urealyticum.

Morbidity after termination of pregnancy in first trimester

The outcome of termination of pregnancy was observed in relation to the preoperative clinical and microbiological findings in 167 women attending a day care abortion unit in Liverpool. Before termination, Chlamydia trachomatis was isolated from the cervix of 19 (11%) of the patients and high counts (greater than 10(4) colour changing units (ccu) per ml of specimen) of mycoplasmas were found in 30 (18%). Coexistent infections with chlamydiae and high counts of mycoplasmas occurred in only seven (4%) women. Trichomonas vaginalis, yeasts, or pathogenic bacteria were found in vaginal swabs from 30 (18%) women. After undergoing termination, seven (4%) women developed pelvic inflammatory disease (PID), five (71%) of whom had yielded C trachomatis before undergoing termination. A further 13 (8%) patients developed minor morbidity of the upper genital tract; high count mycoplasmal infection had been found in seven (54%) and chlamydial infection in three (23%) of these women before termination. In contrast, C trachomatis had been isolated from only 11 (8%) and high counts of mycoplasmas from 23 (16%) of the 147 women who had uneventful recoveries after undergoing termination. No correlation was apparent between the presence of vaginal pathogens before termination and the development of untoward sequelae postoperatively. Neither the history nor clinical examination before termination would have indicated that chlamydial or mycoplasmal infections were present, or that postoperative complications were likely to occur. Abnormal cervical cytology, however, was found in 86 (52%) of women overall, including 15 (79%) of the 19 women with chlamydial infection.

Persistent urethritis due to Ureaplasma urealyticum in conjugal or stable partnerships

A study of four conjugal partnerships is described in which the male partners presented with persistent or recurrent non-gonococcal, non-chlamydial, but ureaplasma positive urethritis. Resolution of symptoms and signs in the male partners was achieved only after treatment to eliminate Ureaplasma urealyticum from both partners.

Evaluation of ciprofloxacin 500 mg twice daily for one week in treating uncomplicated gonococcal chlamydial, and non-specific urethritis in men

Ciprofloxacin, a quinolone antibacterial, was evaluated in the treatment of gonococcal, chlamydial, gonococcal and chlamydial, and non-gonococcal non-chlamydial urethritis. The dosage regimen used was 500 mg orally twice a day for seven days. Of the 56 patients evaluated 22 had gonococcal infection only, 13 were infected with Chlamydia trachomatis only, seven had combined infection, and 14 were harbouring neither of these organisms. Neisseria gonorrhoeae was cleared in all the 29 patients with or without chlamydial infection. Of those who denied having sexual intercourse during the follow-up period, post gonococcal urethritis (PGU) developed in 12 (63%) out of 19, C trachomatis was isolated again from 11 (78%) out of 14, and urethritis recurred in five (55%) out of nine patients with non-gonococcal non-chlamydial infection. There was also evidence that the dosage regimen used was only partially effective against Ureaplasma urealyticum.

Differentiation of ectromelia virus haemagglutinin from haemagglutinins of other poxviruses

The use of mouse erythrocytes in haemagglutinin titrations allows ectromelia virus haemagglutinin (EHA) to be differentiated from the haemagglutinins produced by other members of the variola/vaccinia subgroup of poxviruses.