A "Red Flag" system adds value to medical school admissions interviews

INTRODUCTION

Non-cognitive traits should be considered when selecting candidates to study medicine. However, evaluating these traits remains difficult. We explored whether measuring undesirable non-cognitive behaviour ('Red Flags') added value to a medical school admissions system. Red Flags included rudeness, ignoring the contributions of others, disrespectful behaviour, or poor communication.

METHODS

Following an admissions interview testing non-cognitive attributes in 648 applicants to a UK medical school, we measured the association between interview score and Red Flag frequency. We tested linear and polynomial regression models to evaluate whether the association was linear or non-linear.

RESULTS

In total, 1126 Red Flags were observed. While Red Flags were concentrated among low-scorers, candidates in the highest- and second-highest deciles for interview score still received Red Flags (six and twenty-two, respectively). The polynomial regression model indicated candidates with higher scores received fewer Red Flags, but the association was not linear (F(3644) = 159.8, p = .001, adjusted R2 = 0.42).

CONCLUSIONS

The non-linear association between interview score and Red Flag frequency shows some candidates with desirable non-cognitive attributes will still display undesirable-or even exclusionary-non-cognitive attributes. Recording Red Flag behaviour reduces the likelihood such candidates will be offered a place at medical school.

Disparities in lung transplantation in children

Lung transplantation is a recognized therapy for end-stage respiratory failure in children and young people. It is only available in selected countries and is limited by access to suitable organs. Data on disparities in access and outcomes for children undergoing lung transplantation are limited. It is clear from data from studies in adults, and from studies in other solid organ transplants in children, that systemic inequities exist in this field. While data relating specifically to pediatric lung transplantation are relatively sparse, professionals should be aware of the risk that healthcare systems may result in disparities in access and outcomes following lung transplantation in children.

Equity, Diversity and Inclusion (EDI) in Organ Transplantation: An ESOT Survey About EDI Within ESOT as an Organization and its Educational Activities, and Transplantation Research and Science

The European Society of Organ Transplantation (ESOT) strives to promote equity, diversity, and inclusion (EDI) across all its activities. We surveyed the transplant community's experiences and perspectives regarding EDI within ESOT as an organization and its educational activities, and research in general. A total of 299 respondents completed the questionnaire. About half agreed that ESOT's Executive Committee, Council, and Sections/Committees are diverse and inclusive (51%) and that ESOT promotes EDI in its live and digital educational activities (54%). Forty percent of respondents agreed that scientific and clinical trials in the field of transplantation are diverse and inclusive. Despite the wide distribution of the survey, most of the respondents self-identified as White and were either physician or surgeon. However, the results contribute a unique insight into the experiences and perspectives of the transplantation community regarding EDI. Whilst ESOT is committed to the principles of EDI, perceptions and the high number of proposals show the apparent need to prioritize efforts to embed EDI across ESOT and transplantation science. These data should constitute a starting point for change and provide guidance for future efforts to promote EDI within the transplantation community.

European Society for Organ Transplantation (ESOT)-TLJ 3.0 Consensus on Histopathological Analysis of Pre-Implantation Donor Kidney Biopsy: Redefining the Role in the Process of Graft Assessment

The ESOT TLJ 3.0. consensus conference brought together leading experts in transplantation to develop evidence-based guidance on the standardization and clinical utility of pre-implantation kidney biopsy in the assessment of grafts from Expanded Criteria Donors (ECD). Seven themes were selected and underwent in-depth analysis after formulation of PICO (patient/population, intervention, comparison, outcomes) questions. After literature search, the statements for each key question were produced, rated according the GRADE approach [Quality of evidence: High (A), Moderate (B), Low (C); Strength of Recommendation: Strong (1), Weak (2)]. The statements were subsequently presented in-person at the Prague kick-off meeting, discussed and voted. After two rounds of discussion and voting, all 7 statements reached an overall agreement of 100% on the following issues: needle core/wedge/punch technique representatively [B,1], frozen/paraffin embedded section reliability [B,2], experienced/non-experienced on-call renal pathologist reproducibility/accuracy of the histological report [A,1], glomerulosclerosis/other parameters reproducibility [C,2], digital pathology/light microscopy in the measurement of histological variables [A,1], special stainings/Haematoxylin and Eosin alone comparison [A,1], glomerulosclerosis reliability versus other histological parameters to predict the graft survival, graft function, primary non-function [B,1]. This methodology has allowed to reach a full consensus among European experts on important technical topics regarding pre-implantation biopsy in the ECD graft assessment.

Organ transplants of the future: planning for innovations including xenotransplantation

The future clinical application of animal-to-human transplantation (xenotransplantation) is of importance to society as a whole. Favourable preclinical data relevant to cell, tissue and solid organ xenotransplants have been obtained from many animal models utilizing genetic engineering and protocols of pathogen-free husbandry. Findings have reached a tipping point, and xenotransplantation of solid organs is approaching clinical evaluation, the process of which now requires close deliberation. Such discussions include considering when there is sufficient evidence from preclinical animal studies to start first-in-human xenotransplantation trials. The present article is based on evidence and opinions formulated by members of the European Society for Organ Transplantation who are involved in the Transplantation Learning Journey project. The article includes a brief overview of preclinical concepts and biology of solid organ xenotransplantation, discusses the selection of candidates for first-in-human studies and considers requirements for study design and conduct. In addition, the paper emphasizes the need for a regulatory framework for xenotransplantation of solid organs and the essential requirement for input from public and patient stakeholders.

O45: DEFINING CELL-ENRICHED MICRORNAS TO SUPPORT RATIONAL BIOMARKER SELECTION IN HUMAN RENAL TRANSPLANTATION

Introduction

MicroRNAs are promising biomarkers of renal disease, however the cellular origin of their expression is usually unclear limiting their interpretation when measured in renal biopsies and urine. We hypothesised that by first defining renal cell-enriched microRNAs, we could select biomarkers based on the expected histopathological profile.

Method

Small RNA-sequencing of cortical, proximal tubular (LTL), macrophage (F480), endothelial (CD31) and fibroblast (PDGFRb) populations from the reversible unilateral ureteric obstruction (rUUO) murine model was performed. Hierarchical clustering was used to identify clusters. Findings were translated into an ischaemia reperfusion injury (IRI) model and then into urine samples from renal transplant recipients (n=16) with delayed graft function (DGF) vs. those with primary function.

Result

Kidney injury resulted in significant macrophage infiltration and tubular injury which improved upon reversal. We characterised novel microRNA clusters enriched for each cell type. With injury there was a significant increase in macrophage (p<0.0001), fibroblast (p<0.01) and decrease in proximal tubule (p<0.0001) enriched microRNAs vs. non-enriched microRNAs. We validated macrophage enriched miR-18a, miR-16 and tubular enriched miR-194 in the IRI model, demonstrating that microRNA expression reflected the histological profile. In humans, urinary miR-16 (FC 16.9; p<0.05) and miR-18a (FC 10: p=0.06) were upregulated at day 2 in patients with DGF; outperforming the traditional injury marker KIM1.

Conclusion

This is the first study to characterise cell-enriched microRNAs during renal injury and repair. By defining the source of microRNA expression we were able to rationally select miR-16 and miR-18a as promising urinary biomarkers of renal injury.

Take-home message

We have found that microRNAs have differences in expression between cell types and renal injury states which is important when considering microRNA expression in samples composed of varying cellular composition. By defining the cellular origins of microRNA expression we were able to rationally select microRNA biomarkers of human renal injury.

Differentiation of a Contractile, Ureter-Like Tissue, from Embryonic Stem Cell-Derived Ureteric Bud and Ex Fetu Mesenchyme

BACKGROUND

There is intense interest in replacing kidneys from stem cells. It is now possible to produce, from embryonic or induced pluripotent stem cells, kidney organoids that represent immature kidneys and display some physiologic functions. However, current techniques have not yet resulted in renal tissue with a ureter, which would be needed for engineered kidneys to be clinically useful.

METHODS

We used a published sequence of growth factors and drugs to induce mouse embryonic stem cells to differentiate into ureteric bud tissue. We characterized isolated engineered ureteric buds differentiated from embryonic stem cells in three-dimensional culture and grafted them into ex fetu mouse kidney rudiments.

RESULTS

Engineered ureteric buds branched in three-dimensional culture and expressed Hoxb7, a transcription factor that is part of a developmental regulatory system and a ureteric bud marker. When grafted into the cortex of ex fetu kidney rudiments, engineered ureteric buds branched and induced nephron formation; when grafted into peri-Wolffian mesenchyme, still attached to a kidney rudiment or in isolation, they did not branch but instead differentiated into multilayer ureter-like epithelia displaying robust expression of the urothelial marker uroplakin. This engineered ureteric bud tissue also organized the mesenchyme into smooth muscle that spontaneously contracted, with a period a little slower than that of natural ureteric peristalsis.

CONCLUSIONS

Mouse embryonic stem cells can be differentiated into ureteric bud cells. Grafting those UB-like structures into peri-Wolffian mesenchyme of cultured kidney rudiments can induce production of urothelium and organize the mesenchyme to produce rhythmically contracting smooth muscle layers. This development may represent a significant step toward the goal of renal regeneration.

The impact of age on patient tolerance of mycophenolate following kidney transplantation

BACKGROUND

In Scotland, standard maintenance immunosuppression following kidney transplantation consists of mycophenolate (MPA), tacrolimus and prednisolone irrespective of recipient age. We analyzed the tolerability of this immunosuppression regimen and the association with transplant outcomes.

METHODS

A national, multicentre retrospective analysis of patients transplanted in 2015 and 2016, comparing graft function, acute rejection, significant infection rates and immunosuppression dosing between patients aged 18 and 59 years (Group 1) and ≥60 years (Group 2).

RESULTS

Of the 490 patients, 26% were aged ≥60 years. Acute rejection (AR) rates at 1 year were 15% and 11% in Groups 1 and 2, respectively. Full-dose MPA was poorly tolerated with 53% in Group 1 and 77% in Group 2 requiring dose reduction or cessation. Female gender and age ≥60 years were independent predictors for MPA dose changes. One year following MPA dose reduction, AR risk was low (5%) in Group 2, however, those remaining on full dose MPA had a 79% increased rate of serious infections.

CONCLUSION

The majority of renal transplant recipients aged ≥60 fail to tolerate full-dose MPA. In this group, MPA dose reduction is associated with low rejection rates, but full-dose MPA is associated with high infection rates. We suggest that a tailored approach to immunosuppression in elderly recipients incorporating lower doses of MPA may be appropriate.

How to set up a clinical trial

Clinical trials are considered the gold-standard method for the evaluation of healthcare interventions. However, randomised control trials are complex to perform and many researchers, especially those in the early stages of their career, can find it challenging to know where to start set up, contribute to or lead a trial. This guide provides an introduction to trials and also practical advice to help potential investigators complete their clinical trial to time and to budget by signposting the pathway through the complex regulatory landscape. The authors draw on their own recent experiences of running clinical trials and provide tips and tricks for troubleshooting common problems encountered including trial design and documentation.

Nitrergic relaxations and phenylephrine contractions are not compromised in isolated urethra in a rat model of diabetes

In vivo experiments in a diabetic rat model revealed compromised nitrergic urethral relaxations and increased sensitivity to adrenergic agonists. This study evaluated contractile and relaxation properties of urethral smooth muscle after streptozotocin (STZ)-induced diabetes, in vitro, with the aim of determining whether in vivo deficiencies are related to smooth muscle dysfunction. Urethral tissue was collected from adult female Sprague-Dawley rats naive, STZ-treated, vehicle-treated and sucrose-fed at 9-12 week post treatment. Strips from proximal, mid, and distal urethra were placed in tissue baths and stimulated using electric field stimulation (EFS) and pharmacological agents. nNOS staining was evaluated using immunohistochemistry. Phenylephrine (PE, 10μM) contracted all urethral strips with the highest amplitude in mid urethra, in all treatment groups. Likewise, EFS-induced relaxation amplitudes were larger and were observed more frequently in mid urethra. Relaxations were inhibited by the NOS inhibitor, L-NAME (1-100μM). Sodium nitroprusside (0.01-1μM), an NO donor, reversed PE-induced contractions. No statistical differences were observed between treatment groups with respect to any parameters. Qualitative immunohistochemistry showed no differences in the urethral nNOS innervation patterns across the treatment groups. In summary, nitrergic relaxations and adrenergic-induced contractions in the isolated diabetic rat urethra display similar properties to controls, suggesting no dysfunction on the nitrergic or alpha1 adrenergic receptor function in the smooth muscle. This further implies that compromised urethral relaxation and increased adrenergic agonist sensitivity observed in vivo in this model may be due to the disruption of neural signaling between the urethra and the spinal cord, or within the CNS.

High risk of cytomegalovirus infection following solid organ transplantation despite prophylactic therapy

Cytomegalovirus infection (CMV) in solid organ transplant recipients is a major clinical problem. The aim of this study was to evaluate the incidence of CMV infection and its association with mortality during the first year after transplantation in a large solid organ transplant cohort at the Royal Infirmary of Edinburgh between January 2006 and April 2009. Data including the use of CMV prophylaxis, nature of CMV disease, treatment and deceased date (when appropriate) was collected retrospectively using hospital databases and patient notes for all transplanted patients with detectable CMV viraemia. The outcomes between recipients of kidney and liver transplants in the four CMV donor/recipient serostatus categories (D+R+, D-R-, D+R-, D-R+) were compared. A total of 428 individuals were included. Despite the administration of valganciclovir prophylaxis, CMV disease (syndrome or end-organ involvement) was diagnosed within the year of transplantation in the D+R--group in 31.3% of liver and 19.2% of kidney recipients. All D+R- transplant recipients that received CMV-prophylaxis presented with late-onset CMV disease. Furthermore, the rate of CMV disease in the D+R+-group was markedly higher in renal graft recipients compared to liver recipients (22% vs. 5%). The highest mortality was observed among the D+R+ liver and kidney graft recipients with CMV infection. The high incidence of late-onset CMV disease in D+R- transplant recipients receiving CMV prophylaxis demonstrates that CMV disease remains an important problem after organ transplantation. Furthermore, the surprisingly high mortality in the D+R+-transplant patients with CMV viraemia highlights the need for proactive monitoring of this group.

Inflammatory lymphangiogenesis in a rat transplant model of interstitial fibrosis and tubular atrophy

We have previously reported de novo lymphangiogenesis in human renal allograft nephrectomy specimens that exhibited interstitial fibrosis and tubular atrophy (IFTA). This study examined whether a similar pathology developed in an experimental model of renal transplantation in the rat. Renal transplants were carried out in rats comprising both isografts (Lewis kidneys → Lewis rats) and allografts (Fisher kidneys → Lewis rats). Animals were immunosuppressed in the immediate postoperative period and sacrificed at 12 months. Experimental readouts included lymphatic vessel number and location, inflammatory cell infiltration, interstitial fibrosis, renal function, blood pressure and proteinuria. Rat allografts demonstrated the characteristic features of IFTA with increased macrophage and T cell infiltration and scattered B cells aggregates. Rat allografts exhibited impaired renal function and proteinuria. Although there was no difference in the number of perivascular lymphatic vessels, there was a striking 18-fold increase in the number of interstitial lymphatic vessels in renal allografts. Furthermore, the lymphatic vessel number correlated with the extent of interstitial fibrosis. This rat allograft model of IFTA demonstrates a marked increase in the number of interstitial lymphatic vessels and mirrors previous work in failing human renal allografts.

Identification of neural circuits involved in female genital responses in the rat: a dual virus and anterograde tracing study

The spinal and peripheral innervation of the clitoris and vagina are fairly well understood. However, little is known regarding supraspinal control of these pelvic structures. The multisynaptic tracer pseudorabies virus (PRV) was used to map the brain neurons that innervate the clitoris and vagina. To delineate forebrain input on PRV-labeled cells, the anterograde tracer biotinylated dextran amine was injected in the medial preoptic area (MPO), ventromedial nucleus of the hypothalamus (VMN), or the midbrain periaqueductal gray (PAG) 10 days before viral injections. These brain regions have been intimately linked to various aspects of female reproductive behavior. After viral injections (4 days) in the vagina and clitoris, PRV-labeled cells were observed in the paraventricular nucleus (PVN), Barrington's nucleus, the A5 region, and the nucleus paragigantocellularis (nPGi). At 5 days postviral administration, additional PRV-labeled cells were observed within the preoptic region, VMN, PAG, and lateral hypothalamus. Anterograde labeling from the MPO terminated among PRV-positive cells primarily within the dorsal PVN of the hypothalamus, ventrolateral VMN (VMNvl), caudal PAG, and nPGi. Anterograde labeling from the VMN terminated among PRV-positive cells in the MPO and lateral/ventrolateral PAG. Anterograde labeling from the PAG terminated among PRV-positive cells in the PVN, ventral hypothalamus, and nPGi. Transynaptically labeled cells in the lateral hypothalamus, Barrington's nucleus, and ventromedial medulla received innervation from all three sources. These studies, together, identify several central nervous system (CNS) sites participating in the neural control of female sexual responses. They also provide the first data demonstrating a link between the MPO, VMNvl, and PAG and CNS regions innervating the clitoris and vagina, providing support that these areas play a major role in female genital responses.

Differential effects of simultaneous or sequential administration of paroxetine and WAY-100,635 on ejaculatory behavior

Clinical treatment of depression or anxiety with selective serotonin reuptake inhibitors (SSRIs) often results in delayed ejaculation or anorgasmia. Co-treatment with subtype-selective serotonin receptor antagonists may alter the timing of onset of action and potentiate or reduce sexual side effects. Sexual behavior in male Sprague-Dawley rats was examined after acute administration of the SSRI, paroxetine and the serotonin1A antagonist, WAY-100,635. Acute administration of paroxetine alone did not alter male ejaculatory behavior. However, administration of paroxetine plus WAY-100,635 resulted in a significant delay in mounting behavior and increased the time to ejaculation. Simultaneous administration of paroxetine and WAY-100,635 produced a greater delay in initiation of mounting behavior and ejaculation compared to sequential administration of paroxetine followed by WAY-100,635. The differential effect on sexual behavior or addition of specific serotonin receptor antagonists may be relevant for clinical treatment therapies of premature ejaculation.

Identification of neural pathways involved in genital reflexes in the female: a combined anterograde and retrograde tracing study

The medial preoptic area (MPOA) is important for reproductive behavior in females. However, the descending pathways mediating these responses to the spinal motor output are unknown. The MPOA does not directly innervate the spinal cord. Therefore, pathways mediating MPOA-induced changes in sexual behavior must relay in the brain. The nucleus paragigantocellularis (nPGi) projects heavily to spinal circuits involved in female sexual reflexes and is involved in the tonic inhibition of genital reflexes. However, the periaqueductal gray (PAG) is also important for female sexual behavior. The present study examined the hypothesis that the MPOA output relays through PAG and the nPGi before descending to the spinal cord. We used anterograde and retrograde tracing techniques to examine the descending pathways and relay sites from the MPOA to the spinal cord and the nPGi in the female rat. Injection of biotinylated dextran amine into the MPOA produced dense labeling in specific regions of the PAG and Barrington's nucleus; anterogradely labeled fibers terminated close to neurons retrogradely labeled from the spinal cord in the PAG, Barrington's nucleus, nPGi, lateral hypothalamus and paraventricular nucleus (PVN). Anterogradely labeled fibers and varicosities were also found close to neurons retrogradely labeled from the nPGi in the PAG, lateral hypothalamus and PVN. These results suggest that the major MPOA output relays in the PAG and nPGi before descending to innervate spinal circuits regulating female genital reflexes and that the MPOA plays a multifaceted role in female reproductive behavior through its modulation of PAG output systems.

The Role of Vascular Endothelial Growth Factor in the Kidney in Health and Disease

Vascular endothelial growth factor (VEGF) is a potent endothelial cell mitogen, angiogenic factor and enhancer of vascular permeability. Expressed in the epithelial cells of the developing glomerulus and tubular epithelium, VEGF plays an important role in the development and maintenance of the early vasculature of the kidney. Here, we review the available literature regarding the expression and function of VEGF both in the developing and healthy adult kidney. Furthermore, we highlight how VEGF expression is altered in the diseased kidney and how this modulated expression may impact on and reflect underlying functional changes occurring during the disease process. As discussed, many controversial issues remain, particularly concerning the role of VEGF in the diseased kidney. That VEGF has been proposed as a potential future therapeutic target for the management of some renal diseases requires first that the precise role of VEGF in the normal kidney and various renal pathologies be further and more clearly defined.

Serotonergic projections to the rostroventrolateral medulla from midbrain and raphe nuclei

Double-label fluoresence immunohistochemistry was performed to define serotonergic projections from the raphe and midbrain to the sympathoexcitatory region of the rostroventrolateral medulla (RVLM). Immunolabelling of cholera toxin B subunit retrogradely transported from the pressor region of the RVLM was combined with serotonin (5-HT) immunohistochemistry. Major sources of serotonergic input to the RVLM were shown to include the raphe obscurus, raphe pallidus and raphe magnus with a minor contribution from the ventrolateral, lateral and ventral regions of the periaqueductal gray matter, and the dorsal raphe nucleus. Serotonergic modulation of sympathoexcitatory neurons may establish patterns of sympathetic nerve activity evident in many aspects of cardiovascular regulation.

Selectively bred male rat lines differ in naïve and experienced sexual behavior

Ejaculatory behavior is facilitated by activating 5-hydroxytryptamine(1A) (5-HT(1A)) receptors. The present study examined male sexual behavior in rat lines that were selectively bred for their different hypothermic responses to 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). Sexual behavior was examined in naïve and experienced HDS (high 8-OH-DPAT sensitive), LDS (low 8-OH-DPAT sensitive), and RDS (randomly bred) rats lines. In addition, the effects of 8-OH-DPAT (0.05 mg/kg) and N-(2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl)-N-(2-pyridinyl)-cyclohexane-carboxamide (WAY 100,635; 1 mg/kg) were examined. Naïve HDS animals had diminished ejaculatory behavior (as indicated by a decreased number of intromissions, mounts and ejaculations, increased ejaculation and intromission latency, and longer inter-copulatory interval), compared to the LDS and RDS groups. In addition, the post-ejaculatory interval (PEI) was longer in the HDS group. With experience, the HDS group improved its ejaculatory behavior. Experienced HDS animals had a lower number of intromissions and a longer PEI compared to the LDS group. 8-OH-DPAT facilitated ejaculatory behavior in both HDS and LDS groups. This effect was more pronounced in the LDS group. WAY 100,635 did not alter sexual behavior in either group. In summary, alteration in forebrain 5-HT(1A) receptors in HDS animals may be involved in the ability of naïve rats to achieve ejaculation. 5-HT(1A) receptors are involved in the regulation of resumption of sexual behavior after ejaculation.

Bladder function in female rats: effects of aging and pregnancy

In vivo anesthetized cystometrograms and in vitro bladder tissue strip responses were examined in three groups of female rats: young virgins (3 month), older virgins (8 month), and retired breeders (8-9 month). Significant age-related in vivo changes were observed including greater resting pressures, but smaller voided volumes, void durations and void-to-void intervals in older versus young virgin rats. There were significant age-related changes in the in vitro responses. Greater peak and steady state contractions to high K+-modified Krebs (80 mM) depolarization were observed in young animals compared to older animals. Plus, young virgins exhibited greater sensitivity but smaller maximal, normalized contractions to acetylcholine (ACh) than older virgins. Diminished responses to adenosine-5'-triphosphate (ATP) were detected in young versus older virgin rats. Pregnancy-related changes were compared between retired breeders and their age-matched controls, older virgin rats. In vivo voided volumes were greater in the retired breeders than in the older virgins. Smaller in vitro steady state contractions to high K+-modified Krebs depolarization and smaller normalized contractions to maximal concentrations of ACh were observed in the retired breeders than in the older virgins. Retired breeders exhibited diminished relaxation responses to norepinephrine compared to older virgins. ATP produced greater dose-dependent responses and greater maximal contractions in the retired breeders compared to the older virgins. In conclusion, age-related changes were present even prior to the onset of senescence, and multiple pregnancies altered bladder function.

Oxytocinergic innervation of autonomic nuclei controlling penile erection in the rat

In the rat, spinal autonomic neurons controlling penile erection receive descending pathways that modulate their activity. The paraventricular nucleus of the hypothalamus contributes oxytocinergic fibers to the dorsal horn and preganglionic sympathetic and parasympathetic cell columns. We used retrograde tracing techniques with pseudorabies virus combined with immunohistochemistry against oxytocin and radioligand binding detection of oxytocinergic receptors to evidence the oxytocinergic innervation of thoracolumbar and lumbosacral spinal neurons controlling penile erection. Spinal neurons labelled with pseudo-rabies virus transsynaptically transported from the corpus cavernosum were present in the intermediolateral cell column and the dorsal gray commissure of the thoracolumbar and lumbosacral spinal cord. Confocal laser scanning microscopic observation of the same preparations revealed close appositions between oxytocinergic varicosities and pseudorabies virus-infected neurons, suggesting strongly the presence of synaptic contacts. Electron microscopy confirmed this hypothesis. Oxytocin binding sites were present in the superficial layers of the dorsal horn, the dorsal gray commissure and the intermediolateral cell column in both the thoracolumbar and lumbosacral segments. In rats, stimulation of the paraventricular nucleus induces penile erection, but the link between the nucleus and penile innervation remains unknown. Our findings support the hypothesis that oxytocin, released by descending paraventriculo-spinal pathways, activates proerectile spinal neurons.

5-Hydroxytryptamine2C receptors on spinal neurons controlling penile erection in the rat

The localization of 5-hydroxytryptamine2C receptors in the lumbosacral spinal cord of the rat was investigated using selective antibodies raised against the carboxyl-terminal part of the rat receptor. The distribution of immunoperoxidase labelling at the light microscope level revealed numerous labelled neurons in the gray matter, with a higher intensity in the sacral parasympathetic nucleus, the dorsal gray commissure and particularly the motoneurons of the ventral horn. Confocal microscope analysis showed that immunostaining was mainly intracellular (motoneurons), but could also be associated with the membrane of cell bodies and dendrites. Actually, electron microscope immunogold experiments demonstrated an exclusive staining of the cis-Golgi apparatus. Following pseudo-rabies virus transsynaptic retrograde labelling from the corpus cavernosum, labelled neurons were found in the sacral parasympathetic nucleus and the dorsal gray commissure of the L6-S1 segments. All virus-labelled neurons exhibited 5-hydroxytryptamine2C receptor immunoreactivity. These results indicate that all parasympathetic preganglionic neurons and their related interneurons which contribute to the innervation of cavernosal tissue bear 5-hydroxytryptamine2C receptors. In the sacral parasympathetic nucleus, most neurons which were retrogradely-labelled from the pelvic ganglion with Fast Blue also showed 5-hydroxytryptamine2C receptor immunoreactivity. In the ventral horn, motoneurons retrogradely labelled from the ischiocavernosus muscle and the bulbospongiosus muscle, both of which are involved in erection and ejaculation, were also 5-hydroxytryptamine2C receptor-immunopositive. The supraspinal serotoninergic control of erection at the lumbosacral level therefore appears to be strongly associated with the activation of 5-hydroxytryptamine2C receptors, consistent with the proerectile properties of 5-hydroxytryptamine2C agonists.

Identification of CNS neurons innervating the rat prostate: a transneuronal tracing study using pseudorabies virus

The spinal and brain neurons that innervate the rat prostate were identified using the transneuronal tracing technique. Three groups of rats were prepared: (1) nerve intact, (2) bilateral pelvic nerve cut and right hypogastric nerve cut and (3) bilateral hypogastric nerve cut and right pelvic nerve cut. Pseudorabies virus (PRV) was injected into the ventral prostate on the left side. After 2-4 days, the rats were perfused transcardially under deep anesthesia and the spinal cord and brain removed. PRV-labelled cells were identified using immunohistochemistry. After 3 days survival, sympathetic and parasympathetic preganglionic neurons were labelled with PRV. In addition, spinal interneurons were found in the dorsal gray commissure (DGC) of T13-S1. Rats with only one hypogastric nerve intact resulted in spinal labelling of sympathetic preganglionic neurons in the DGC and ipsilateral intermediolateral cell column (IML). In addition, many spinal interneurons were found from L1 to L6 in the medial gray. Rats with only one pelvic nerve intact displayed PRV-labelled cells in the parasympathetic preganglionic nucleus ipsilateral to the injection site. Spinal interneurons were present in the region of the IML and in the medial cord. In the brain, areas predominately labelled with PRV included the nucleus gigantocellularis and paragigantocellularis, raphe magnus, raphe pallidus, A5, Barrington's nucleus, central gray, ventral tegmental area, the paraventricular nucleus of the hypothalamus, lateral hypothalamus and medial preoptic area. These data demonstrate the sympathetic and parasympathetic spinal circuits and demonstrate the overlap of supraspinal innervation of the spinal interneurons.

A comparative study of the Abrams-Griffiths nomogram and the linear passive urethral resistance relation to determine bladder outlet obstruction

PURPOSE

The Abrams-Griffiths and linear passive urethral relationship (PURR) nomograms are commonly used to diagnose bladder outlet obstruction. To the best of our knowledge there are no clinical studies comparing these 2 evaluations to determine if they similarly predict the findings of bladder outlet obstruction.

MATERIALS AND METHODS

From October 1994 through December 1996 multichannel urodynamic studies were performed in 72 men with lower urinary tract symptoms. The data from each urodynamic study were plotted on the Abrams-Griffiths and PURR nomograms.

RESULTS

Using the Abrams-Griffiths nomogram 23 patients (46%) were unobstructed, 15 (21%) were equivocal for obstruction and 24 patients (33%) were obstructed. When the linear PURR nomogram was applied to the pressure-flow data in each group all unobstructed cases were categorized into grade 0 or 1 (no obstruction), equivocal into grade 2 (mild obstruction) and obstructed into grades 3 through 6 (moderate to severe obstruction).

CONCLUSIONS

The Abrams-Griffiths and linear PURR nomograms are helpful and comparable clinical tools to assess lower urinary tract symptoms in men. The linear PURR nomogram not only detects the presence of bladder outlet obstruction but grades its severity, which may be helpful to monitor treatment.

Effects of prenatal morphine and cocaine exposure on spinal sexual reflexes in male and female rats

Previous studies demonstrated that in utero exposure to morphine or cocaine differentially alters adult sexual behaviors, which are dependent on circulating gonadal hormones in male and female rats. In the present study, the effects of in utero morphine and cocaine exposure on the urethrogenital reflex were examined. The urethrogenital reflex is thought to be a hormone-independent spinal sexual reflex in both males and females. This reflex is tonically inhibited by supraspinal neurons but can be consistently evoked by urethral stimulation in the spinally transected animals. Prenatal morphine or cocaine exposure did not remove the supraspinal inhibition of the urethrogenital reflex in spinally intact male or female rats. In spinally transected animals, the urethrogenital reflex was qualitatively similar in all groups. However, morphine-exposed males required a stronger stimulus to elicit the urethrogenital reflex but once elicited, the frequency of the urethrogenital reflex was significantly higher compared to either controls or cocaine-exposed males. In contrast, in female rats, neither prenatal morphine nor cocaine exposure had any effect on the urethrogenital reflex. Thus, the urethrogenital reflex appears to be differentially affected by prenatal exposure to morphine in males and females.

Identification of central nervous system neurons that innervate the bladder body, bladder base, or external urethral sphincter of female rats: a transneuronal tracing study using pseudorabies virus

Transneuronal tracing techniques were used to identify the putative spinal and brainstem neurons involved in continence and voiding in the female rat. Pseudorabies virus, Bartha's K strain, was injected into either the external urethral sphincter, the bladder base, or the bladder body. After 3-5 days, the rats were perfused with fixative, and virus-labelled cells were identified by using immunohistochemistry. External urethral sphincter (EUS) injections resulted in labelling of pudendal motoneurons in the dorsolateral nucleus of L6. Putative spinal interneurons were found in the medial cord from T13 to S1 and in the lateral gray of T13-L2 and L5-S1. After both bladder base and bladder body injections, the majority of pseudorabies virus-labelled cells were found in the lateral gray and medial cord of L6-S1. A number of those found in the intermediolateral cell column resembled the parasympathetic preganglionic neurons; the remaining neurons in the lateral and medial gray were presumed to be interneurons. Very few pseudorabies virus-labelled cells were found rostral to T10. In the brainstem, transneuronally labelled cells were found in the parapyramidal medullary reticular formation, Barrington's nucleus, raphe magnus, raphe pallidus, subcoeruleus pars alpha, locus coeruleus, the A5 noradrenergic cell group, and ventromedial periaqueductal gray after all injection sites. Pseudorabies virus-labelled cells were also seen in the forebrain following the longest survival times; areas consistently labelled included the lateral hypothalamus, the parvocellular region of the paraventricular nucleus, and the medial preoptic area. These studies indicate that there is a substantial overlap of central nervous system neurons that innervate the EUS and the bladder in the female.

CNS cell groups involved in the control of the ischiocavernosus and bulbospongiosus muscles: a transneuronal tracing study using pseudorabies virus

Transneuronal tracing techniques were used to identify spinal and brainstem neurons involved in the control of perineal muscles in the male rat. Two penile muscles, the bulbospongiosus and ischiocavernosus muscles, were injected with Bartha's strain of pseudorabies virus. After survival periods of 2, 4, and 5 days, the rats were killed and viral labeled neurons identified by immunohistochemistry. After a 2 day survival period, only pudendal motoneurons were labeled. More spinal and brainstem neurons were labeled at longer survival times. Putative spinal interneurons were found from T13 to S1. Large numbers of neurons were found in the lateral horn of the T13-L2 and L6-S1 segments which contain sympathetic and parasympathetic preganglionic neurons, respectively. However, retrograde labeling experiments verified that very few of the viral neurons were preganglionic neurons. Other labeled neurons were found in the intermediate cord, especially around the central canal. Relatively few labeled neurons were seen in the dorsal or ventral horn. In the brainstem, consistent labeling was seen in the ventrolateral medulla, raphe pallidus, and magnus, the A5 and locus ceruleus noradrenergic cell groups. Barrington's nucleus in the pontine tegmentum, the periaqueductal gray, and the paraventricular nucleus of the hypothalamus. The transneuronal labeling was consistent with what is currently known of the central nervous system (CNS) control of the perineal muscles.

Effects of beta-FNA on sympathoadrenal, cardiovascular, and analgesic responses to DAMPGO at rest and during stress

To elucidate further the role of mu-opioid receptors in mediating analgesia and cardiovascular function at rest and during stress, rats were pretreated ICV with either saline (5 microliters) or beta-funaltrexamine (beta-FNA, 5 nmol/5 microliters), a noncompetitive opioid receptor antagonist that inactivates irreversibly mu receptors, 2 days prior to [D-Ala2, N MePhe4, Gly5-ol]enkephalin (DAMPGO, 1 nmol, ICV) administration. Pretreatment with beta-FNA blocked DAMPGO-induced analgesia as measured by the tail-flick test. DAMPGO also produced an increase in blood pressure (BP), sympathoadrenal outflow, and a bradycardia. Pretreatment with beta-FNA converted the DAMPGO-induced bradycardia to a tachycardia, significantly reduced the DAMPGO-induced increase in epinephrine by 60%, and the norepinephrine response by 45%, and attenuated mildly the increase in BP due to DAMPGO. In saline-treated rats, restraint stress evoked an increase in HR, BP, and plasma catecholamines. Pretreatment with beta-FNA partially attenuated the increase in HR in response to stress. In the presence of DAMPGO, restraint stress resulted in a further bradycardia, which was significantly blocked by pretreatment with beta-FNA. Stress also produced increases in BP and plasma catecholamines, which were not prevented by pretreating rats with beta-FNA. These results indicate that beta-FNA may not have inactivated all the receptors accessible to DAMPGO which control BP, or alternatively, beta-FNA may selectively inactivate a subtype of mu receptors. In addition, brain mu opioid receptors appear to be significantly involved in mediating supraspinal analgesia and regulating parasympathetic outflow to the heart and sympathoadrenal release of catecholamines.

Central nervous system neurons identified after injection of pseudorabies virus into the rat clitoris

Transneuronal tracing techniques were used to identify putative spinal and brain neurons involved in the efferent control of the clitoris. Pseudorabies virus was injected into the rat clitoris and virus-labeled neurons were identified immunohistochemically. Neurons were found primarily in L5-S1 segments of the spinal cord. In addition, virus-labeled cells were found in T12-L4 and S2-S4. In the brain, virus-labeled cells were found in the nucleus paragigantocellularis, raphe pallidus, raphe magnus, Barrington's nucleus, ventrolateral central gray, hypothalamus and medial pre-optic region. These data identify a multisynaptic circuit of neurons which may be involved in clitoral control.

Parasympathetic preganglionic neurons in the spinal cord involved in uterine innervation are cholinergic and nitric oxide-containing

BACKGROUND

The purpose of this study was to elucidate parasympathetic preganglionic neurons in the spinal cord that project axons in pathways to the uterus and to reveal their neurotransmitter phenotype.

METHODS

"Uterine-related" neurons were identified by using a combination of retrograde axonal tracers: (1) Fluorogold injected into the ganglia of termination of preganglionic fibers, and (2) a transganglionic axonal tracer (pseudorabies virus) injected into the uterus. Immunohistochemistry was used to reveal virus-labeled neurons and their neurotransmitter marker.

RESULTS

Double-labeled (Fluorogold+pseudorabies virus) "uterine" preganglionic neurons were identified in the sacral parasympathetic nucleus of the rat lumbosacral spinal cord. Subpopulations of neurons in the sacral parasympathetic nucleus were shown to be immunoreactive for choline acetyltransferase or nitric oxide synthase. Double-staining immunohistochemistry (for pseudorabies virus+neurotransmitter enzyme) revealed that some of the uterine-related preganglionic neurons were cholinergic and some nitric oxide synthase-containing.

CONCLUSIONS

These results demonstrate a subpopulation of preganglionic parasympathetic neurons in the sacral parasympathetic nucleus that are involved in uterine innervation. In addition, both acetylcholine and nitric oxide could be used to modify activity in the postganglionic neurons, which directly innervate the uterus.

Lack of effect of carbon monoxide inhibitor on relaxation induced by electrical field stimulation in corpus cavernosum

Carbon monoxide has been proposed as a possible neurotransmitter because of its ability to bind to the iron atom of the heme of guanylyl cyclase, which is similar to that of nitric oxide. To determine whether carbon monoxide exerts an effect on the penis, strips of rabbit corpus cavernosum were mounted in an organ bath for isometric tension studies and the effect of zinc deuteroporphyrin, an inhibitor of heme oxygenase which metabolizes hemoprotein and releases carbon monoxide, on relaxation induced by electrical field stimulation (neurally mediated) was determined. Also observed was relaxation induced by electrical field stimulation after incubation with atropine and guanethidine to isolate nonadrenergic noncholinergic neurotransmission. Zinc deuteroporphyrin (10(-6) M, 10(-5) M, 10(-4) M and 3 x 10(-4) M) did not affect relaxation induced by electrical field stimulation in the absence or presence of guanethidine and atropine. Therefore, it appears that carbon monoxide does not contribute to neurally mediated relaxation of the rabbit corpus cavernosum.

Serotonergic neurotoxic lesions facilitate male sexual reflexes

The effects of the neurotoxin 5,7 dihydroxytryptamine (5,7 DHT) on the urethrogenital reflex was examined in anesthetized male rats. Both ICV and intrathecal administration of 5,7 DHT produced a marked depletion (92%) of spinal 5-hydroxytryptamine (5-HT) and 5-hydroxyindole acetic acid (5-HT IAA) levels. ICV but not intrathecal administration of 5,7 DHT also caused a moderate reduction in 5-HT and 5-HT IAA levels in the medulla and hypothalamus (40-48%). No reduction in adrenergic levels were observed. In spinally intact, vehicle-treated rats the urethrogenital reflex could not be evoked. However, the urethrogenital reflex could be evoked in rats pretreated with either ICV or intrathecal 5,7 DHT prior to section of the spinal cord. These data support the hypothesis that 5-HT mediates the descending inhibition of male sexual reflexes.

Stimulation of the hypothalamus initiates the urethrogenital reflex in male rats

The urethrogenital (UG) reflex is a spinal sexual reflex which is tonically inhibited in the intact male rat by neurons in the nucleus paragigantocellularis (nPGi). The medial preoptic area of the hypothalamus (MPOA) is involved in the activation of male sexual behavior. The present study examines the effect of hypothalamic stimulation on the UG reflex in the intact male rat. Areas of the hypothalamus were stimulated bilaterally with either electrical stimulation or D,L-homocysteic acid (DLH) and the presence of the UG reflex examined. Stimulation of discrete aras of the hypothalamus evoked the UG reflex. The UG reflex could be initiated in the absence of genital stimulation. Microinjections of DLH into the MPOA also initiate the UG reflex. These data suggest that stimulation of neurons in the MPOA overcome the inhibition by the nPGi and facilitate spinal genital reflexes leading to ejaculation.

Distribution and co-localization of 5-hydroxytryptamine, thyrotropin-releasing hormone and substance P in the cat medulla

This study demonstrates the co-existence of three neurochemicals in ventral medullary neurons of the cat utilizing fluorescence immunohistochemistry. Neurons containing 5-hydroxytryptamine, thyrotropin-releasing hormone and substance P were identified within the rostrocaudal extent of the medulla, specifically within the raphe pallidus and raphe magnus and in the reticular formation of the ventrolateral medulla in the nucleus paragigantocellularis lateralis. Within the raphe pallidus the majority of 5-hydroxytryptamine-containing neurons were co-localized with thyrotropin-releasing hormone and substance P. However, in the raphe magnus the majority of stained neurons contained 5-hydroxytryptamine and thyrotropin-releasing hormone but were devoid of substance P. In the ventrolateral medulla two major populations of neurons were identified rostral to the inferior olivary nuclei, one containing 5-hydroxytryptamine and thyrotropin-releasing hormone, while a more lateral group contained substance P alone. More caudally, at the level of the inferior olives, the majority of 5-hydroxytryptamine-containing cells also displayed immunoreactivity for thyrotropin-releasing hormone and substance P. A consistent finding in both the ventromedial and ventrolateral regions of the medulla was a population of 5-hydroxytryptamine-containing cells which did not stain for either thyrotropin-releasing hormone or substance P. The functional role of co-localized neurochemicals remains unknown but co-existence of neurotransmitter substances in medullary neurons may allow for specific and multiple actions in the spinal cord.

Central nervous system innervation of the penis as revealed by the transneuronal transport of pseudorabies virus

Transneuronal tracing techniques were used in order to identify putative spinal interneurons and brainstem sites involved in the control of penile function. Pseudorabies virus was injected into the corpus cavernosus tissue of the penis in rats. After a four day survival period, rats were perfused with fixative and virus-labelled neurons were identified by immunohistochemistry. Postganglionic neurons were retrogradely labelled in the major pelvic ganglia. In the spinal cord, sympathetic and parasympathetic preganglionic neurons were labelled transneuronally. Presumptive interneurons were also labelled in the lower thoracic and lumbosacral spinal cord in locations consistent with what is currently known about such interneurons. In the brainstem, transneuronally labelled neurons were found in the medulla, pons and hypothalamus. Regions consistently labelled included the nucleus paragigantocellularis, parapyramidal reticular formation of the medulla, raphe pallidus, raphe magnus, A5 noradrenergic cell group, Barrington's nucleus and the paraventricular nucleus of the hypothalamus. This study confirmed previous studies from our lab and others concerning the preganglionic and postganglionic neurons innervating the penis. The number, morphology and location of these neurons were consistent with labelling seen following injection of conventional tracers into the penis. The brainstem nuclei labelled in this study were also consistent with what is currently known about the brainstem control of penile function. The labelling appeared to be highly specific, in that descending systems involved in other functions were not labelled. These results provide further evidence that the pseudorabies virus transneuronal tracing technique is a valuable method for identifying neural circuits mediating specific functions.

Lesions of the nucleus paragigantocellularis alter ex copula penile reflexes

The effects of electrolytic lesions of the rostral nucleus paragigantocellularis (nPGi) were examined on ex copula sexual reflexes in male rats. Bilateral lesions of the nPGi significantly reduced (by 50%) the onset of the first ex copula reflex, which usually was a glans erection. In addition, the number of dorsiflexions (flips) was significantly increased. In the anesthetized spinally intact rat the urethrogenital reflex cannot be evoked. However, after chronic bilateral lesions of the rostral nPGi, half of the rats tested displayed the urethrogenital reflex prior to section of the spinal cord. These data support a role for the rostral nPGi in the descending inhibition of male sexual reflexes.

A role for 5-hydroxytryptamine in descending inhibition of spinal sexual reflexes

Neurons in the region of the rostral nucleus paragigantocellularis (nPGi) mediate the inhibition of spinal sexual reflexes. Anatomical and pharmacological evidence is presented supporting a role for 5-hydroxytryptamine (5-HT) in this inhibition. Neurons in the rostral nPGi project to the ventral horn in the vicinity of the pudendal motoneurons. A significant number (78% ipsilateral) of these neurons contain 5-HT. Anterograde tracing with Phaseolus leucoagglutinin (PHA-L) confirmed the nPGi projection to pudendal motoneuron and interneuronal areas of the lumbar cord. 5-HT immunoreactive fibers and presumptive terminals surround the pudendal motoneurons. Urethral stimulation, in the anesthetized male rat, elicited penile erections, ejaculation and rhythmic contractions of the perineal muscles, we have used the term coitus reflex to describe this response. Intrathecal injection of 5-HT (4-50 micrograms) abolished the coitus reflex. Methysergide (1-10 mg/kg i.v.) prevented the 5-HT induced blockade of the coitus reflex. These data support the hypothesis that 5-HT is involved in the descending inhibition of spinal sexual reflexes.