Mapping lumbar efferent and afferent spinal circuitries via paddle array in a porcine model

BACKGROUND

Preclinical models are essential for identifying changes occurring after neurologic injury and assessing therapeutic interventions. Yucatan miniature pigs (minipigs) have brain and spinal cord dimensions like humans and are useful for laboratory-to-clinic studies. Yet, little work has been done to map spinal sensorimotor distributions and identify similarities and differences between the porcine and human spinal cords.

NEW METHODS

To characterize efferent and afferent signaling, we implanted a conventional 32-contact, four-column array into the dorsal epidural space over the lumbosacral spinal cord, spanning the L5-L6 vertebrae, in two Yucatan minipigs. Spinally evoked motor potentials were recorded bilaterally in four hindlimb muscles during stimulation delivered from different array locations. Then, cord dorsum potentials were recorded via the array by stimulating the left and right tibial nerves.

RESULTS

Utilizing epidural spinal stimulation, we achieved selective left, right, proximal, and distal activation in the hindlimb muscles. We then determined the selectivity of each muscle as a function of stimulation location which relates to the distribution of the lumbar motor pools.

COMPARISON WITH EXISTING METHODS

Mapping motoneuron distribution to hindlimb muscles and recording responses to peripheral nerve stimulation in the dorsal epidural space reveals insights into ascending and descending signal propagation in the lumbar spinal cord. Clinical-grade arrays have not been utilized in a porcine model.

CONCLUSIONS

These results indicate that efferent and afferent spinal sensorimotor networks are spatially distinct, provide information about the organization of motor pools in the lumbar enlargement, and demonstrate the feasibility of using clinical-grade devices in large animal research.

A micro-LED implant and technique for optogenetic stimulation of the rat spinal cord

To date, relatively few studies have used optogenetic stimulation to address basic science and therapeutic questions within the spinal cord. Even less have reported optogenetic stimulation in the rat spinal cord. This is likely due to a lack of accessible optogenetic implants. The development of a device that can be fabricated and operated by most laboratories, requiring no special equipment, would allow investigators to begin dissecting the functions of specific neuronal cell-types and circuitry within the spinal cord, as well as investigate therapies for spinal ailments like spinal cord injury. Here, we describe a long-term implantable μLED device designed for optogenetic stimulation of the spinal cord in awake, freely moving rats that is simple enough to be fabricated, implanted and operated by most laboratories. This device, which sits above the dorsal cord, can induce robust movements for at least 6 weeks without causing physical or thermal damage to the underlying spinal cord. In this regard, the presented μLED device could help tease apart the complexities of the spinal cord and uncover potential future therapeutics.

Optogenetic surface stimulation of the rat cervical spinal cord

Electrical intraspinal microstimulation (ISMS) at various sites along the cervical spinal cord permits forelimb muscle activation, elicits complex limb movements and may enhance functional recovery after spinal cord injury. Here, we explore optogenetic spinal stimulation (OSS) as a less invasive and cell type-specific alternative to ISMS. To map forelimb muscle activation by OSS in rats, adeno-associated viruses (AAV) carrying the blue-light sensitive ion channels channelrhodopsin-2 (ChR2) and Chronos were injected into the cervical spinal cord at different depths and volumes. Following an AAV incubation period of several weeks, OSS-induced forelimb muscle activation and movements were assessed at 16 sites along the dorsal surface of the cervical spinal cord. Three distinct movement types were observed. We find that AAV injection volume and depth can be titrated to achieve OSS-based activation of several movements. Optical stimulation of the spinal cord is thus a promising method for dissecting the function of spinal circuitry and targeting therapies following injury.

NEW & NOTEWORTHY Optogenetics in the spinal cord can be used both for therapeutic treatments and to uncover basic mechanisms of spinal cord physiology. For the first time, we describe the methodology and outcomes of optogenetic surface stimulation of the rat spinal cord. Specifically, we describe the evoked responses of forelimbs and address the effects of different adeno-associated virus injection paradigms. Additionally, we are the first to report on the limitations of light penetration through the rat spinal cord.

Proportion of Tubal Factor Infertility due to Chlamydia: Finite Mixture Modeling of Serum Antibody Titers

In this study, we examined whether the proportion of tubal factor infertility (TFI) that is attributable to Chlamydia trachomatis, the population excess fraction (PEF), can be estimated from serological data using finite mixture modeling. Whole-cell inclusion immunofluorescence serum antibody titers were recorded among infertile women seen at St. Michael's Hospital in Bristol, United Kingdom, during the period 1985-1995. Women were classified as TFI cases or controls based on laparoscopic examination. Finite mixture models were used to identify the number of component titer distributions and the proportion of serum samples in each, from which estimates of PEF were derived. Four titer distributions were identified. The component at the highest titer was found only in samples from women with TFI, but there was also an excess of the second-highest titer component in TFI cases. Minimum and maximum estimates of the PEF were 28.0% (95% credible interval: 6.9, 50.0) and 46.8% (95% credible interval: 23.2, 64.1). Equivalent estimates based on the standard PEF formula from case-control studies were 0% and over 65%. Finite mixture modeling can be applied to serological data to obtain estimates of the proportion of reproductive damage attributable to C. trachomatis Further studies using modern assays in contemporary, representative populations should be undertaken.

MMP9-sensitive polymers mediate environmentally-responsive bivalirudin release and thrombin inhibition

MMP9-responsive bivalirudin-HPMA copolymers were synthesized for direct, local administration in rat spinal cord contusion injury models. Polymer-conjugated bivalirudin peptides maintained activity while demonstrating enzyme-mediated release upon MMP9 exposure and prolonged release from hyaluronic acid/methylcellulose (HAMC) hydrogels compared to free bivalirudin peptide. Localized administration of bivalirudin copolymers in vivo at the site of rat spinal cord injury decreased cellular proliferation and astrogliosis, suggesting the bivalirudin copolymer and HAMC hydrogel system are a promising therapeutic intervention for reducing immediate inflammatory responses and long term scarring.

Mycoplasma genitalium is associated with symptomatic urethritis

In order to further investigate the epidemiology of Mycoplasma genitalium, 680 men attending departments of genitourinary medicine in Bristol, Bath and Truro were studied. M. genitalium was detected in 36 men (5.3%) and was present at all three clinics. Clinically, both urethritis and the presence of a urethral discharge and/or dysuria, but not penile irritation were independently associated with the detection of M. genitalium, the former being with the strongest association (odds ratio [OR] 10.76, 95% confidence interval [CI] [3.10–37.29], P < 0.0001; OR 3.01, 95% CI [1.28–7.05], P = 0.011 and OR 1.28, 95% CI [0.61–2.69], P = 0.51, respectively). In men with urethritis, those with a discharge and/or dysuria were more likely to have M. genitalium detected (OR 2.61, 95% CI [1.09–6.25], P = 0.032). We found no association with younger age or a recent change of sexual partner. In conclusion, M. genitalium is associated with symptomatic urethritis.

An oral fluid test for syphilis

We have developed a time-resolved fluorescence immunoassay to detect antibodies to Treponema pallidum recombinant antigens in oral fluid specimens. Using an 'Oracol' swab, oral fluid was collected from 34 subjects with a serological diagnosis of syphilis and 97 seronegative controls. Using a cut-off of three standard deviations over control mean, the sensitivity and specificity of the assay in all subjects with positive syphilis serology was 76.5% and 97.9%, respectively. In those with early syphilis, the sensitivity and specificity of the assay was 100% and 97.9%. In a non-outbreak situation, screening clinic attendees for syphilis using oral fluid specimens is potentially useful when collection of blood is not practicable. In addition, it may have much to offer in outreach projects and epidemiological investigations.

Should we still be testing for asymptomatic non-specific urethritis in departments of genitourinary medicine?

It has recently been advocated that non-invasive testing with first-catch urine specimens using nucleic acid amplification techniques, to detect Chlamydia trachomatis and Neisseria gonorrhoeae, should replace routine microscopy on asymptomatic men. Although it is assumed that this strategy will be cost effective, the available evidence suggests that this will result in fewer sexually transmitted infections being averted than continuing the current practice of screening for urethritis and testing for both microorganisms in asymptomatic men. This review article summarizes the available evidence and argues that research is urgently needed in order to properly evaluate the cost-effectiveness of detecting urethritis in asymptomatic men.

Presentation of clinically suspected persistent chlamydial infection: a case series

In vivo antimicrobial resistance has yet to be documented in Chlamydia trachomatis; however, there have been anecdotal reports of persistent infection. The purpose of this case series was to describe a group of patients who have persistent chlamydia infection despite adequate treatment and where re-infection was considered unlikely. Patients were selected using a clinical questionnaire. For inclusion patients had to have tested positive for C. trachomatis, at least twice, using a nucleic acid amplification test despite having been fully compliant with at least two rounds of recommended therapy and be deemed to be at low risk of re-infection. Patients were grouped into categories based on sexual behaviour. Twenty-eight patients are included in this case series; 46% declared no sexual contact since initial diagnosis (category 1), a further 36% declaring contact that was considered low risk of re-infection (categories 2-4); 61% showed signs and symptoms at initial presentation increasing to 75% at re-attendance. Thirty-nine percent of patients received azithromycin only while 48% received doxycycline also. This case series identifies patients with persistent chlamydia despite receiving treatment. There is a need for a case definition of clinical treatment failure, development of susceptibility testing methods and guidance on appropriate treatment for patients with persistent infection.

Therapeutic intraspinal microstimulation improves forelimb function after cervical contusion injury

OBJECTIVE

Intraspinal microstimulation (ISMS) is a promising method for activating the spinal cord distal to an injury. The objectives of this study were to examine the ability of chronically implanted stimulating wires within the cervical spinal cord to (1) directly produce forelimb movements, and (2) assess whether ISMS stimulation could improve subsequent volitional control of paretic extremities following injury.

APPROACH

We developed a technique for implanting intraspinal stimulating electrodes within the cervical spinal cord segments C6-T1 of Long-Evans rats. Beginning 4 weeks after a severe cervical contusion injury at C4-C5, animals in the treatment condition received therapeutic ISMS 7 hours/day, 5 days/week for the following 12 weeks.

MAIN RESULTS

Over 12 weeks of therapeutic ISMS, stimulus-evoked forelimb movements were relatively stable. We also explored whether therapeutic ISMS promoted recovery of forelimb reaching movements. Animals receiving daily therapeutic ISMS performed significantly better than unstimulated animals during behavioural tests conducted without stimulation. Quantitative video analysis of forelimb movements showed that stimulated animals performed better in the movements reinforced by stimulation, including extending the elbow to advance the forelimb and opening the digits. While threshold current to elicit forelimb movement gradually increased over time, no differences were observed between chronically stimulated and unstimulated electrodes suggesting that no additional tissue damage was produced by the electrical stimulation.

SIGNIFICANCE

The results indicate that therapeutic intraspinal stimulation delivered via chronic microwire implants within the cervical spinal cord confers benefits extending beyond the period of stimulation, suggesting future strategies for neural devices to promote sustained recovery after injury.

Reactive nonproliferative gliosis predominates in a chronic mouse model of glaucoma

In many CNS diseases, proliferation becomes dysregulated; cells divide and participate in pathological processes. Gliosis is a fundamental CNS response to trauma or disease in which cell hypertrophy and proliferation play prominent roles. The DBA/2J mouse is a glaucoma model in which mice experience gliosis concomitant with raised intraocular pressure that leads to a slow and progressive retinal ganglion cell axonopathy. We sought to determine if glaucomatous changes in DBA/2 retina would alter the regulation of cell proliferation, specifically in relation to retinal glia. Astrocyte and Müller glia populations within DBA/2 retina upregulated glial fibrillary acidic protein mRNA and protein compared with C57Bl/6; microglial cell number increased twofold from 4 to 10 months. Various bromodeoxyuridine (BrdU) injection paradigms were used to label dividing cells in DBA/2 and C57Bl/6 retina at 4 and 10 months of age. Very modest cell division in the retina, primarily in ganglion cell and inner nuclear layers, was observed at all ages. Immunohistochemistry indicated cell turnover primarily of NG2+ pericytes and Iba1+ microglia; astrocytes and Müller glia did not proliferate. There were no significant differences in BrdU+ cell numbers in 4 and 10-month-old retina, though 4-month retina had generally fewer BrdU+ cells than 10-month. C57Bl/6 retinas had fewer BrdU+ cells than DBA/2 retinas at all ages. These data show that, in contrast to gliosis in other CNS trauma and neurodegenerative diseases, glaucomatous changes in retina do not include substantive cell proliferation. Retinal changes in a chronic model of glaucoma engender a reactive, not proliferative, gliosis response.

Treatment of Chlamydia trachomatis in North Thames region 2003

Following on from the survey of techniques used for testing chlamydia, a multi-centre re-audit of the treatment of C. trachomatis in genitourinary clinic attendees in the North Thames region from February to March 2003 was performed. This showed an improvement since our previous audit with a significant increase in the number of centres following national guidelines in antibiotic prescribing and offering test of cure in clinically indicated cases.

Diagnosis of Chlamydia trachomatis in North Thames region 2003

A multi-centre re-audit of tests used for chlamydia diagnosis in GU medicine clinic attendees from February 2003 to March 2003 in the North Thames region showed improvements since our previous audit in 1999, with a significant increase in the proportion of clinics using nucleic acid amplification tests and non-invasive testing.

The chlamydia screening studies: rationale and design

BACKGROUND

Screening has been recommended to reduce the prevalence and morbidity associated with genital chlamydia infection in the United Kingdom.

METHODS

We describe the rationale and study design of the Chlamydia Screening Studies (ClaSS), a collaborative project designed to evaluate screening outside genitourinary medicine clinics. A non-selective, active screening approach in 16-39 year olds randomly sampled from 27 general practice lists in the Bristol and Birmingham areas formed the basis of interlinked studies: a case-control study was used to investigate factors to improve the targeting of screening; participants with chlamydia were invited to enroll in a randomised controlled trial to evaluate partner notification conducted in primary care; and laboratory based studies were used to assess the best specimens and tests. We also explored psychosocial effects of screening and partner notification and modelled the cost effectiveness of the programme.

CONCLUSION

Results from four pilot practices show that mailing of specimens for chlamydia testing is feasible but that it is difficult to achieve high response rates with postal screening. The high prevalence of asymptomatic infection in men suggests that efforts to screen men for chlamydia should be strengthened.

A novel polymerase chain reaction assay to detect Mycoplasma genitalium

AIMS

To design and validate a polymerase chain reaction (PCR) assay targeting the 16S rRNA gene of Mycoplasma genitalium.

METHODS

Primers were designed that were complementary to the 16S rRNA gene sequence of M genitalium. After optimisation of the reaction conditions, the PCR was tested against nine M genitalium strains, a dilution series of M genitalium DNA, and a panel of common microorganisms. The PCR was also challenged in parallel with a published assay against 54 urine specimens from men with urethritis.

RESULTS

The expected 341 bp product was produced on amplification of material from all M genitalium strains and from none of the other microorganisms tested. The lower limit of detection was 50 genome copies. The new assay detected M genitalium DNA in nine of 54 men with urethritis, in comparison with eight positive specimens detected with the alternative PCR.

CONCLUSIONS

This novel PCR targeting the M genitalium 16S rRNA gene has been optimised and now provides a sensitive and specific alternative or addition to the available MgPa gene targeting assays.

Do all men attending departments of genitourinary medicine need to be screened for non-gonococcal urethritis?

We investigated the influence of symptoms and signs on the detection of Chlamydia trachomatis, Mycoplasma genitalium and Ureaplasma urealyticum organisms (ureaplasmas) in men with non-gonococcal urethritis (NGU). Two hundred and forty-two men attending the Jefferiss Wing at St Mary's Hospital for a sexual health assessment were evaluated, of whom 169 had NGU. Urethral inflammation was diagnosed if there were either > or =5 polymorphonuclear leucocytes (PMNLs) per high-power field (HPF) in five or more microscope fields of a Gram-stained urethral smear, or > or =10 PMNLs per HPF in five or more fields of a Gram-stained thread from 15-20 mL of a first-passed urine (FPU) specimen. C. trachomatis was diagnosed by direct immunofluoresence, M. genitalium by a polymerase chain reaction assay and ureaplasmas by culture. On multivariate analysis, to control for potential confounding by age, ethnicity, sexual lifestyle and co-infection, an urethral discharge remained significantly associated with the detection of C. trachomatis and M. genitalium in men with acute urethritis [OR 12.3, 95% CI (2.39-63.5) and OR 35.2, 95% CI (3.9-319.6), respectively], but dysuria or penile irritation did not. The detection of ureaplasmas was not associated with any clinical feature. In addition, on multivariate analysis men with NGU who were either symptomatic or had an observable discharge were more likely to have C. trachomatis or M. genitalium detected [(OR 6.92, 95% CI 1.41-33.9) and (OR 5.18, 95% CI 0.99-27.1), respectively], but not ureaplasmas (OR 1.19, 95% CI 0.33-4.35). The findings suggest that in men with acute NGU, symptoms or signs, and in particular a urethral discharge, are associated with the detection of C. trachomatis and M. genitalium, but not ureaplasmas. Currently, there is no precise answer to the question of whether all men attending a GUM clinic need to be screened for NGU, but if clinically asymptomatic NGU is found not to be associated with a sexually transmitted pathogen, the UK clinical guidelines requiring the preparation of a urethral smear from such men would need to be revised.

Management of Chlamydia trachomatis genital tract infection in Genitourinary Medicine clinics in the United Kingdom's North Thames Region 1999

Assessment of clinical management of Chlamydia trachomatis genital tract infection was made, with particular regard to the UK National Guideline. Questionnaires for self-completion, mailed to lead clinicians in 31 Genitourinary Medicine (GUM) clinics in the North Thames Region between May and June 1999, focused on policies and practice. Audit of actual management of up to 10 most recent cases (5 male and 5 female) attending each clinic within the past 2 years was also undertaken. Twenty-two units (71% response) completed the survey questionnaire and 23 units (74% response) audited a total of 229 cases (males=108, females=118, sex not stated=3). Findings indicate that GUM clinics are managing these infections largely as recommended in the national guideline. Nucleic acid amplification techniques will supersede established diagnostic tests for GUM clinics in North Thames, increasing costs for the service, but also sensitivity of detection.

Adult spinal cord stem cells generate neurons after transplantation in the adult dentate gyrus

The adult rat spinal cord contains cells that can proliferate and differentiate into astrocytes and oligodendroglia in situ. Using clonal and subclonal analyses we demonstrate that, in contrast to progenitors isolated from the adult mouse spinal cord with a combination of growth factors, progenitors isolated from the adult rat spinal cord using basic fibroblast growth factor alone display stem cell properties as defined by their multipotentiality and self-renewal. Clonal cultures derived from single founder cells generate neurons, astrocytes, and oligodendrocytes, confirming the multipotent nature of the parent cell. Subcloning analysis showed that after serial passaging, recloning, and expansion, these cells retained multipotentiality, indicating that they are self-renewing. Transplantation of an in vitro-expanded clonal population of cells into the adult rat spinal cord resulted in their differentiation into glial cells only. However, after heterotopic transplantation into the hippocampus, transplanted cells that integrated in the granular cell layer differentiated into cells characteristic of this region, whereas engraftment into other hippocampal regions resulted in the differentiation of cells with astroglial and oligodendroglial phenotypes. The data indicate that clonally expanded, multipotent adult progenitor cells from a non-neurogenic region are not lineage-restricted to their developmental origin but can generate region-specific neurons in vivo when exposed to the appropriate environmental cues.

Regenerating the damaged central nervous system

It is self-evident that the adult mammalian brain and spinal cord do not regenerate after injury, but recent discoveries have forced a reconsideration of this accepted principle. Advances in our understanding of how the brain develops have provided a rough blueprint for how we may bring about regeneration in the damaged brain. Studies in developmental neurobiology, intracellular signalling and neuroimmunology are bringing the regeneration field closer to success. Notwithstanding these advances, clear and indisputable evidence for adult functional regeneration remains to be shown.

Use of 5-bromo-4-chloro-3-indolyl-alpha-D-N-acetylneuraminic acid in a novel spot test To identify sialidase activity in vaginal swabs from women with bacterial vaginosis

The validity of measuring vaginal sialidase activity to identify bacterial vaginosis (BV) was determined by using 5-bromo-4-chloro-3-indolyl-alpha-D-N-acetylneuraminic acid in a near-patient test. The sensitivity and specificity of the test for prediction of BV were 95.6 and 96.3%, respectively. Positive and negative predictive values were 95.6 and 96.3%, respectively. This test may be an alternative to Gram staining.

Proliferation and differentiation of progenitor cells throughout the intact adult rat spinal cord

The existence of multipotent progenitor populations in the adult forebrain has been widely studied. To extend this knowledge to the adult spinal cord we have examined the proliferation, distribution, and phenotypic fate of dividing cells in the adult rat spinal cord. Bromodeoxyuridine (BrdU) was used to label dividing cells in 13- to 14-week-old, intact Fischer rats. Single daily injections of BrdU were administered over a 12 d period. Animals were killed either 1 d or 4 weeks after the last injection of BrdU. We observed frequent cell division throughout the adult rodent spinal cord, particularly in white matter tracts (5-7% of all nuclei). The majority of BrdU-labeled cells colocalized with markers of immature glial cells. At 4 weeks, 10% of dividing cells expressed mature astrocyte and oligodendroglial markers. These data predict that 0.75% of all astrocytes and 0.82% of all oligodendrocytes are derived from a dividing population over a 4 week period. To determine the migratory nature of dividing cells, a single BrdU injection was given to animals that were killed 1 hr after the injection. In these tissues, the distribution and incidence of BrdU labeling matched those of the 4 week post injection (pi) groups, suggesting that proliferating cells divide in situ rather than migrate from the ependymal zone. These data suggest a higher level of cellular plasticity for the intact spinal cord than has previously been observed and that glial progenitors exist in the outer circumference of the spinal cord that can give rise to both astrocytes and oligodendrocytes.

The influence of bacterial vaginosis on in-vitro fertilization and embryo implantation during assisted reproduction treatment

There is growing evidence that the pathogenic effects of bacterial vaginosis may not be confined to the lower genital tract. Possible associations with infertility and effects on fertilization and implantation were studied in patients undergoing in-vitro fertilization (IVF) treatment. High vaginal swabs taken at the time of oocyte collection were assessed by Gram staining. The prevalence of bacterial vaginosis and of intermediate and normal flora in 301 patients was 25.6, 14.0 and 60.4% respectively. Bacterial vaginosis was more prevalent in patients with tubal (31.5%, n = 149) compared with non-tubal (19.7%, n = 152) infertility (odds ratio (OR) 1.87, CI 1.11-3.18, P = 0.02). Bacterial vaginosis did not have an adverse effect on fertilization rate. Further, no significant difference in implantation rates was seen when comparing bacterial vaginosis (15. 8%, OR 1.03, CI 0.66-1.61) and intermediate flora (13.1%, OR 0.82, CI 0.45-1.52) with normal flora (15.5%). Though confidence intervals around the observations were relatively wide, the findings suggest that routine screening for bacterial vaginosis in the hope of improving the success of IVF treatment is not justified. The prevention of complications in pregnancy associated with bacterial vaginosis might be a more relevant indication for screening at the time of IVF treatment, in particular patients with tubal disease, if treatment were shown to be effective for that particular purpose. However, antibiotic treatment before IVF has been shown to be positively disadvantageous for IVF by encouraging other organisms.

Mucinase and sialidase activity of the vaginal microflora: implications for the pathogenesis of preterm labour

Evidence linking bacterial vaginosis (BV) to chorioamnionitis and spontaneous preterm birth is mounting. Successful treatment of BV could reduce the rate of late miscarriage and preterm birth. Mucinase and sialidase activity have been implicated in the pathogenesis of BV. This study extends the work of previous studies to investigate sialidase, other known mucin degrading enzymes and overall mucin degrading activity in samples of vaginal fluid from women with and without BV. Samples from 31 women were diagnosed for BV, and tested for enzyme activity using established assays. Activity was recorded in all samples. Significant increases in activity were detected in BV samples for sialidase using a mucin (BSM P<0.005) and serum type glycoprotein (AGP P<0.005) substrates, beta-galactosidase (P<0.001), and beta-N-acetylhexosaminidase (P<0.01). No significant increases in BV patients were detected in O-glycanase, proteinase, arylesterase, sulphatase or whole mucinase activities. These results support the hypothesis that certain BV-associated enzymes may detrimentally affect the mucosal barrier, permitting bacteria access to the uterus.

Neurotrophin-3 and brain-derived neurotrophic factor induce oligodendrocyte proliferation and myelination of regenerating axons in the contused adult rat spinal cord

Functional loss after spinal cord injury (SCI) is caused, in part, by demyelination of axons surviving the trauma. Neurotrophins have been shown to induce oligodendrogliagenesis in vitro, but stimulation of oligodendrocyte proliferation and myelination by these factors in vivo has not been examined. We sought to determine whether neurotrophins can induce the formation of new oligodendrocytes and myelination of regenerating axons after SCI in adult rats. In this study, fibroblasts producing neurotrophin-3 (NT-3), brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor, nerve growth factor, basic fibroblast growth factor, or beta-galactosidase (control grafts) were transplanted subacutely into the contused adult rat spinal cord. At 10 weeks after injury, all transplants contained axons. NT-3 and BDNF grafts, however, contained significantly more axons than control or other growth factor-producing grafts. In addition, significantly more myelin basic protein-positive profiles were detected in NT-3 and BDNF transplants, suggesting enhanced myelination of ingrowing axons within these neurotrophin-producing grafts. To determine whether augmented myelinogenesis was associated with increased proliferation of oligodendrocyte lineage cells, bromodeoxyuridine (BrdU) was used to label dividing cells. NT-3 and BDNF grafts contained significantly more BrdU-positive oligodendrocytes than controls. The association of these new oligodendrocytes with ingrowing myelinated axons suggests that NT-3- and BDNF-induced myelinogenesis resulted, at least in part, from expansion of oligodendrocyte lineage cells, most likely the endogenous oligodendrocyte progenitors. These findings may have significant implications for chronic demyelinating diseases or CNS injuries.

Association of antibodies to Chlamydia trachomatis heat-shock protein 60 kD with chronic nongonococcal urethritis

Ninety male patients with acute nongonococcal urethritis (NGU) who presented for follow-up 10-92 days after initiation of treatment were evaluated. A polymerase chain reaction assay and direct fluorescence antibody test were used to detect Chlamydia trachomatis at presentation and during follow-up. Chlamydial heat-shock protein 60 kD (hsp60) serology with an enzyme-linked immunosorbent assay and C. trachomatis serology with a microimmunofluoresence test were undertaken. In 62 (69%) of the men, evidence of chronic urethritis was noted during follow-up. C. trachomatis was detected in only two patients during follow-up. Chlamydial hsp60 antibody was associated with the development of chronic urethritis between 10 and 92 days after treatment began (P < .04), that is, at 10-29 days (P < .02) and at 30-92 days (P < .008). These results are consistent with the theory that immune response to hsp60 is important in the development of this chronic disease. The results also suggest that chronic NGU is not a consequence of continued production of hsp60 by C. trachomatis.

A quantitative spatial analysis of the blood-spinal cord barrier. II. Permeability after intraspinal fetal transplantation

In previous experiments we utilized quantitative autoradiography to temporally describe vascular permeability of a radiolabeled vascular tracer following spinal contusion injury in the rat. In the present report we compare these findings with permeability assessments following fetal grafting in the contused rat spinal cord. At 10 days postinjury, Embryonic Day 14 spinal tissue was grafted into the lesioned spinal cord of Sprague-Dawley rats. At 7, 14, and 28 days postgrafting the alpha-aminoisobutyric acid (AIB) technique was used to assess blood-to-tissue transfer rates in graft and host tissue over several segments of the injured spinal cord. Regional changes in permeability were assessed using four distinct image analysis techniques. Using these methods, we have previously shown that contusion injury alone results in a chronic relapse in vascular permeability. The present data indicate that fetal transplants at 7 days postgrafting have AIB transfer rates that are significantly above uninjured control levels and are similar in magnitude to neighboring host spinal tissue. In addition, permeability in 14- and 28-day intraspinal grafts decreased relative to that of the 7-day transplant group, but remained significantly elevated at and rostral to the injury epicenter. Alternately, graft and host tissue in regions caudal to the injury epicenter (e.g., T10--L2) acquired a functional barrier to AIB as early as 14 days posttransplantation. These experiments suggest that graft development occurs in a different manner or at a different rate in segments of the injured spinal cord rostral and caudal to the injury site. Additionally, it appears that vascular permeability of the injured spinal cord can be influenced by the process of intraspinal transplantation.

A quantitative spatial analysis of the blood-spinal cord barrier. I. Permeability changes after experimental spinal contusion injury

Blood-spinal cord barrier (BSB) permeability was measured using quantitative autoradiography following contusion injury to the rat spinal cord. Permeability was assessed by calculating blood-to-tissue transfer constants (Ki values) for the vascular tracer [14C]-alpha-aminoisobutyric acid (AIB) in injured (3, 7, 14, and 28 days postinjury), laminectomy control, and uninjured control animals. Permeability was quantitated using four separate imaging techniques in gray and white matter throughout the rostro-caudal extents of the forming lesion. Away from the epicenter, gray matter permeability was further differentiated within discrete spinal lamina using computerized templates. Regardless of the type of analysis used, increased AIB permeability (Ki values) was noted at all survival times in all tissue regions with respect to both uninjured and laminectomy control groups. The data indicate a large increase in individual Ki values throughout the dorsoventral axis of the spinal cord at 3 days postinjury (approximately 6-9 ml/kg/min). By 7 days, Ki values were quantitatively smaller (approximately 4-5 ml/kg/min) in all regions compared with 3-day tissues. Despite further attenuation of AIB uptake in the gray matter at 14 and 28 days postinjury, circumferential white matter tracts showed a secondary increase in permeability compared to 7-day tissue. Permeability in the white matter at 14-28 days postinjury (approximately 5-6 ml/kg/min) was comparable to that at 3 days postinjury (6-7 ml/kg/min). Measurements of the axial distribution of AIB permeability indicate increased BSB permeability over several segments rostral and caudal to the lesion epicenter (approximately 3 cm in both directions). Secondary elevations of AIB transfer in the spinal white matter between 14 and 28 days were colocalized with zones of immunohistochemically defined microglial clusters. The known plasticity of this cell type in response to changes in the extracellular microenvironment suggests that the spinal white matter at later survival times (14-28 days postinjury) is an area of dynamic vascular and/or axonal reconstruction. The implications of increased permeability to both tissue injury and neural regeneration are discussed.

Antigen capture ELISA for the heat shock protein (hsp60) of Chlamydia trachomatis

AIMS

To develop an indirect ELISA using the heat shock protein (hsp60) of Chlamydia trachomatis as antigen.

METHODS

The hsp60 gene was amplified by PCR, expressed in the vector pDEV-107 and transformed into Escherichia coli. The recombinant protein, expressed as a beta-galactosidase fusion product, was captured onto a solid phase using a monoclonal antibody directed against beta-galactosidase. Following incubation with goat anti-human antibody conjugated to peroxidase and colour development on addition of peroxidase substrate, antibody recognition of antigen was quantified by optical density at 492 nm.

RESULTS

A sensitive and relatively specific ELISA to detect hsp60 has been produced, which can be exploited to determine the antibody response to C trachomatis hsp60.

CONCLUSIONS

This assay will permit the future investigation of the immunopathogenesis of persistent inflammation following C trachomatis infection.

Quantitative analysis of vascularization and cytochrome oxidase following fetal transplantation in the contused rat spinal cord

In the normal adult central nervous system, a coupling between energy consumption and vascular density is well established. Likewise, the survival of fetal neural tissue grafts is highly dependent on the establishment of functional vascular integration with the host. However, to what degree graft vascularization and tissue metabolism influence the normal host response to traumatic injury has not been extensively studied. In the present report, embryonic day 14 fetal spinal cord suspension grafts were made into the lesion epicenter of subchronic (10 days) contusion-injured rats. Three months later, intraspinal transplants were analyzed using correlative cytochrome oxidase histochemistry and vascular morphometric analysis. The same approaches were applied to the host spinal cord and injured, non-transplanted animals in order to determine the ability of a graft to alter the level of post-injury vascularization and/or metabolism. In general, graft vascular density was increased over that measured in normal or injured gray matter. Vascular density in gray matter near the host/graft interface was markedly increased when compared to either gray matter of the same spinal level in injured non-grafted animals or normal control spinal gray matter. Vascular changes were not noted in gray matter 3 mm distal to the lesion epicenter (rostral or caudal) in all groups analyzed. Cytochrome oxidase was up-regulated at this time in the graft and gray matter at the host/graft interfaces when compared to either gray matter of the same spinal level in injured, non-grafted animals or that of uninjured controls. These data indicate that an intraspinal transplant placed into the contused adult rat spinal cord reaches a metabolic capacity that is likely to be associated with high levels of oxidative metabolism in the well-vascularized graft neuropil. In addition, transplantation chronically alters vascularization and metabolic patterns of adjacent spinal gray matter following contusion injury.

Fetal transplantation following spinal contusion injury results in chronic alterations in CNS glucose metabolism

Glucose utilization of the injured rat spinal cord was determined using the autoradiographic technique of Sokoloff et al. (33). Animals were analyzed chronically (2 and 3 months) after spinal contusion injury alone or when a spinal lesion was followed by subchronic (10-day) intraparenchymal fetal spinal transplantation. At 2 and 3 months postinjury, spinal glucose utilization was reduced in dorsal gray and white matter above and below the lesion site. In addition, sensory regions of the forebrain and brain stem (e.g., nucleus gracilis and ventral posterior medial nucleus of the thalamus) had a lower basal metabolic rate than control animals. Decreased metabolic rates in supraspinal regions were reversed by the presence of a spinal graft at 3 but not at 2 months postinjury. Furthermore, gray matter in animals receiving an intraspinal transplant had elevated glucose utilization rates for several spinal segments rostral and caudal to the lesion epicenter. Graft glucose utilization was higher at 2 months (80-90 mumol/100 g/min) than at 3 months (60-70 mumol/100 g/min) posttransplantation. These data are the first quantitative metabolic imaging of spinal and brain metabolism following spinal contusion injury and fetal transplantation. The study suggests that intraspinal transplants can become functionally integrated with adjacent host gray matter and can chronically alter specific postinjury metabolic patterns.

The role of Chlamydia trachomatis in urethritis and urethral symptoms in women

One hundred and fifty women who attended a genitourinary medicine clinic and who required a speculum examination were investigated to determine the association between Chlamydia trachomatis and urethral symptoms and signs. Those who had taken antibiotics with anti-chlamydial activity within 3 months or those who were menstruating, pregnant or using an intrauterine contraceptive device were excluded. C. trachomatis infection of the urethra, or infection of the urethra and cervix together, combined with each separately, were strongly associated with > = 5 polymorphonuclear (PMN) leucocytes per high-power field (x 1000) in a Gram-stained urethral smear (P < 0.00005 and P < 0.0005, respectively). This appeared not to arise from leucocyte contamination from the lower genital tract. However, C. trachomatis infection of the urethra was not associated with symptoms of dysuria or frequency. In conclusion, it seems likely that C. trachomatis infection of the urethra in women probably causes urethritis which is usually asymptomatic. Women who have objective evidence of urethritis might best be managed by appropriate antibiotic therapy and counselling, and advice that partners should attend for review.