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Biomedical subjects

P J Horner

Publications and source records attributed to P J Horner.

At least 19 recordsLinked to original sources
PubMed1998

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.

Animals↗
PubMed1997

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.

Adult↗
PubMed1996

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.

Animals↗
PubMed1996

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.

Aminoisobutyric Acids↗
PubMed1996

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.

Aminoisobutyric Acids↗
PubMed1996

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.

Blotting, Western↗
PubMed1995

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.

Animals↗
PubMed1994

Limited value of two widely used enzyme immunoassays for detection of Chlamydia trachomatis in women.

Enzyme immunoassays (EIAs) are widely used to diagnose chlamydial infections in patients attending genitourinary medicine clinics. They are relatively easy to perform and are suitable for testing large numbers of samples. The objective of this study was to determine what proportion of women with chlamydial infection, defined as the presence of Chlamydia trachomatis in a cervical smear or deposit and/or in the urinary tract, detected by means of a sensitive direct fluorescent antibody test could also be identified by using two commercially available EIAs to test cervical samples. On hundred fifty-one women attending the genitourinary medicine clinic at St. Mary's Hospital, London, were enrolled. The use of the Chlamydiazyme (Abbott Diagnostics, UK) and MicroTrak (Syva, UK) EIAs resulted in the identification of only 56% and 63%, respectively, of women with chlamydial infection detected by direct fluorescent antibody staining. Thus, the EIAs available for detection of chlamydiae in cervical samples are inadequate for identifying all infected women. Improvement might be achieved by testing multiple samples or by resorting to tests of greater sensitivity.

Chlamydia Infections↗
PubMed1994

Chlamydia trachomatis in women: the more you look, the more you find.

OBJECTIVE: To determine the extent to which testing of multiple sites and samples is required to define whether a woman is Chlamydia trachomatis-positive. DESIGN: One-hundred and fifty women attending the Genitourinary Medicine clinic at St Mary's Hospital were enrolled; they had not received antichlamydial antibiotics in the previous three months, were not in a high-risk group for HIV infection, or pregnant, or using an intrauterine contraceptive device. Thirty-two women were re-examined three months after recruitment. METHODS: An urethral specimen was Gram stained (smear) and cultured for gonococci. Another urethral specimen was taken to detect C trachomatis elementary bodies (EBs) by the MicroTrak direct fluorescent antibody (DFA) test (Syva). An endocervical swab specimen was Gram stained (smear) and cultured for gonococci. One of two other endocervical swabs was used for the DFA test and was then placed in medium which was centrifuged in a MicroCentaur at 13,000 rpm for 10 min; the deposit was examined by using the DFA test. The first 15-20 ml of voided urine (first pass urine; FPU) was also centrifuged and the deposit tested similarly. RESULTS: Of 182 cervical smears and/or deposits tested for C trachomatis, 38 were positive; more cervical deposits (37) than smears (26) were positive and, of these, one-fifth of the deposits and one-third of the smears contained fewer than 10 elementary bodies. Of 162 paired urethral smears and FPU deposits available, one or other specimen of 36 pairs was chlamydia-positive, that is 31 smears and 32 deposits; of these, two-fifths of the smears and half of the deposits contained fewer than 10 EBs. Of 150 sets of cervical and urinary tract samples tested, 31 were chlamydia-positive at both sites, six in the cervix alone and four in the urinary tract alone. Of 139 women for whom there were valid first visit sample results, 36 (26%) were chlamydia-positive in the cervix, 34 (25%) in the urinary tract and 41 (29%) had at least one sample from either site positive. Overall, DFA tests of deposits from centrifuged cervical specimens achieved the highest sensitivity (88%) and those of cervical smears the lowest (70%). CONCLUSIONS: Deposits from centrifuged cervical specimens were C trachomatis-positive more often than were cervical smears. Testing deposits from centrifuged urines was as successful as testing urethral smears. One-fifth (cervical deposits) to one-half (urine deposits) of specimens contained fewer than 10 EBs. The urinary tract was chlamydia-positive almost as frequently as the cervix but both sites needed to be tested to define whether a woman was chlamydia-positive.

Cervix Uteri↗
PubMed1993

Association of Mycoplasma genitalium with acute non-gonococcal urethritis.

Chlamydia trachomatis is known to be a cause of acute non-gonococcal urethritis (NGU), though the aetiology of this disorder is not fully understood. Mycoplasma genitalium has been isolated from a few men with NGU, but culture has remained difficult and reliable detection became possible only with a specific polymerase chain reaction (PCR). We have used the PCR to examine the role of M genitalium in NGU. M genitalium was detected in urethral samples from 24 (23%) of 103 men with symptoms, signs, or both, of acute NGU, but from only 3 (6%) of 53 men without NGU (p < 0.006). This association was independent of the presence of C trachomatis and could not be explained by differences in age, ethnic, origin, lifetime number of sexual partners or a change in sexual partner during the previous 3 months. The clinical response of the mycoplasma-positive men to doxycycline treatment was at least as satisfactory as that of the chlamydia-positive men. These findings suggest that the association of M genitalium with NGU is likely to be causal, a notion consistent with the known virulence characteristics of this microorganism and its ability to cause urethritis in male sub-human primates.

Acute Disease↗