Improvement in International Prostate Symptom Score after prostatic urethral lifts is dependent on prostatic volume.

INTRODUCTION: Prostatic urethral lifts (PUL) provide improvement in urinary symptoms for men with benign prostatic hyperplasia (BPH). The aim of this study is to determine operative factors associated with improvement in urinary symptoms after PUL in men with bothersome BPH. MATERIALS AND METHODS: Men with BPH undergoing PUL at a single, tertiary center were identified from 2019 to 2022. Inclusion criteria included documented prostate volume as well as preoperative and postoperative cystoscopic images of the prostatic urethra. Multivariate regression modeling was performed to determine the predictive factors-including prostate volume, number of implants, and degree of unobstructed prostatic urethral channel-for improvement in International Prostate Symptom Score (IPSS) after PUL. RESULTS: Of the 47 men, the distribution of prostate volume was 1 patient with < 30 grams, 33 patients with 30-79 grams, five patients with 80-100 grams, and six patients with > 100 grams. The mean number of implants used was six implants. The mean preoperative and postoperative IPSS were 23 and 14, respectively. The mean (standard error (SE)) change and percent change in IPSS score following PUL was 14 and 60%, respectively. The mean percent improvement in prostatic urethral channel after anterior clip placements was 67%. On multivariate analysis, larger prostate volume was associated with greater change in IPPS follow surgery (p = 0.0091) while number of implants and percent of prostatic urethral opening were not associated with change in IPSS (p = 0.3094 and p = 0.2249, respectively). CONCLUSION: Men with larger prostates are associated with greater improvement in urinary symptom after PUL regardless of number of implants utilized and degree of prostatic urethral channel opening after prostatic implants.

High-density surface electromyographic assessment of pelvic floor hypertonicity in IC/BPS patients: a pilot study.

INTRODUCTION AND HYPOTHESIS: To assess the feasibility of objectively assessing pelvic floor hypertonicity (PFH) in women with interstitial cystitis/bladder pain syndrome (IC/BPS) using an intra-vaginal high-density surface electromyography (HD-sEMG) probe. METHODS: Seven female subjects (mean age 44 ± 13 years) with a prior diagnosis of IC/BPS were recruited. A full digital pelvic examination was administered to identify hypertonic muscles. Intra-vaginal HD-sEMG was acquired during rest. Root-mean-squared (RMS) amplitude during rest was calculated for each channel to define a hypertonicity index and hypertonic zone. Innervation zones (IZs) were identified from the bipolar mapping of decomposed HD-sEMG signals and summarized into an IZ distribution mapping. RESULTS: Of the seven subjects recruited, five had normal pelvic floor muscle tone and two exhibited hypertonicity upon muscle palpation. Subjects with PFH demonstrated a higher hypertonicity index (12.6 ± 3.5 vs. 4.5 ± 1.2) in sessions 1 and 2. The hypertonic zone defined by the 64-channel RMS mapping coincided with the digital pelvic examination findings. The corresponding IZs were localized for each motor unit. The hypertonicity indices between two consecutive sessions were well correlated (CC = 0.95). CONCLUSIONS: This study represents the first effort to employ intra-vaginal HD-sEMG to assess PFH in women with IC/BPS. Our results demonstrate the feasibility of HD-sEMG to provide a quantitative diagnosis of PFH and the precise localization of hypertonic muscles and IZs. The proposed HD-sEMG-based techniques provide promising tools for clinical diagnosis and treatment of PFH, such as the personalized guidance of BoNT injections.

Use of Botulinum Toxin in the Genitourinary System.

Botulinum toxin injection has been widely accepted by the urology and urogynecology medical communities as a safe and effective treatment for refractory urinary incontinence. There are two approved genitourinary indications for botulinum toxin. OnabotulinumtoxinA (onaBoNTA) 200 U for the treatment of urinary incontinence due to detrusor overactivity associated with a neurologic condition (e.g., spinal cord injury, multiple sclerosis) in adults who have an inadequate response to or are intolerant of an anticholinergic medication. In addition, onaBoNTA 100 U is used for the treatment of overactive bladder with symptoms of urinary incontinence, urgency, and frequency, in adult patients who have an inadequate response to or are intolerant of an anticholinergic medication. We will discuss the application of botulinum toxin for genitourinary indications with a focus on bladder injection and on potential use of BoNT use in the prostate and pelvic floor.

Safety, Feasibility, and Efficacy of Transcutaneous Tibial Nerve Stimulation in Acute Spinal Cord Injury Neurogenic Bladder: A Randomized Control Pilot Trial.

OBJECTIVES: We investigated whether transcutaneous tibial nerve stimulation (TTNS) in acute spinal cord injury was safe and feasible, and could achieve neuromodulation and improve cystometrogram parameters during acute inpatient rehabilitation. MATERIALS AND METHODS: Participants were consecutive acute traumatic spinal cord injury patients admitted for acute inpatient rehabilitation, randomized to a 2-week trial of TTNS v sham stimulation. Primary outcomes were safety and feasibility of TTNS and secondary outcomes were bladder measures based on pre- and post-TTNS cystometrogram by group and within groups, including bladder capacity, detrusor hyperreflexia, pressures, and detrusor-sphincter dyssynergia, as well as filling sensations and desire to void. The principle investigator and subjects were blinded to treatment allocation. RESULTS: A total of 19 subjects consented to the study and completed the stimulation protocol. Morbidity was similar between groups and compliance was 100% to the TTNS protocol. Based on a lack of rehabilitation interruptions and comments from staff, TTNS was feasible. Post-cystometrogram parameters were significant for lower volumes until sensation in the control group and prolonged volumes until sensation in the TTNS group. The control group had significant changes of increased detrusor-sphincter dyssynergia and decreased bladder capacity. This was not significantly changed in the TTNS group. CONCLUSIONS: TTNS is a safe and feasible modality that can be performed during inpatient rehabilitation of acute traumatic spinal cord injury. Bladder capacity and episodes of detrusor-sphincter dyssynergia significantly worsened in the control group and did not significantly change in the TTNS group, suggesting that TTNS can alter the course of neurogenic bladder via neuromodulation.

Non-surgical urologic management of neurogenic bladder after spinal cord injury.

PURPOSE: To review the available data on non-surgical management for neurogenic bladder in patients with spinal cord injury (SCI). Before the introduction of urinary catheters and antibiotics, neurogenic bladder was one of the main culprits for death in those patients with SCI. Currently, the management of neurogenic bladder is focused in improving quality of life and preserving renal function. METHODS: A literature review was performed and therapeutic management for neurogenic bladder was divided in six sections: (1) intermittent bladder catheterization; (2) indwelling catheters; (3) condom catheter drainage; (4) reflex voiding and bladder expression with Valsalva or Credé; (5) oral drug therapy of the spinal cord injured bladder; and (6) botulinum neurotoxin (BoNT). RESULTS: Intermittent catheterization is recommended as the preferable method for management of neurogenic bladder in patients with SCI based on limited high-quality data. However, this may not be feasible or available to all and other alternative options include condom catheter drainage or indwelling catheters such as urethral catheters or suprapubic tube, reflex voiding, and bladder expression with Valsalva or Credé. Non-invasive medical therapies are the key to improve incontinence, urodynamic parameters, and quality of life in this population. Botulinum neurotoxin has revolutionized the management of neurogenic bladder in the last two decades decreasing the need for reconstruction or diversion. CONCLUSION: The Joint SIU-ICUD (Société Internationale d'Urologie) (International Consultation on Urological Diseases) International Consultation reviewed the available presented data and provided specific conclusions and recommendations for each non-surgical urologic method to address neurogenic bladder after SCI.

Botulinum Toxin to Treat Neurogenic Bladder.

Alteration in neural control from suprapontine areas to the nerves innervating the bladder can lead to bladder dysfunction and the development of a neurogenic bladder (NGB). Patients with NGB often suffer from urinary incontinence, which can lead to adverse events such as urinary tract infections and decubiti, in addition to creating a large care burden for family members or healthcare providers and significantly impairing patient quality of life. The common failure of anticholinergic medications has spurned the development of second-line treatments, including the use of botulinum toxin. OnabotulinumtoxinA (onaBoNT-A; BOTOX, Allergan, Inc.) was approved by the U.S. Food and Drug Administration (FDA) in 2011 to treat neurogenic detrusor overactivity in patients with urinary incontinence resulting from a NGB. In this review the authors summarize pertinent results from key trials leading to FDA approval of onaBoNT-A as well as more recent long-term data.

Male chronic pelvic pain: An update.

INTRODUCTION: Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) and interstitial cystitis/bladder pain syndrome collectively referred to as urologic CPPS (UCPPS) is defined by the absence of identifiable bacterial infection as a cause for the chronic pain and urinary symptoms. METHODS: A PubMed search of all recent relevant articles using the keywords/phrases: CPPS, CPPS, and male pelvic pain, was conducted. RESULTS: CPPS has a high worldwide prevalence and its negative impact on quality of life compares with or exceeds common chronic morbidities. Triggers include certain comestibles as well as psychosocial factors that promote catastrophizing and illness focused behavior. Several validated tools are currently available to help diagnose and direct targeted therapy. Treatment should begin with the most simple and least invasive based on the presenting clinical phenotype. CONCLUSIONS: Although no gold-standard treatment exists, a multidisciplinary approach with multimodal therapy gives the UCPPS patient the best chance of symptom relief.

Risk Classification for Interstitial Cystitis/Bladder Pain Syndrome Using Machine Learning Based Predictions.

OBJECTIVE: To improve diagnosis of interstitial cystitis (IC)/bladder pain syndrome(IC) we hereby developed an improved IC risk classification using machine learning algorithms. METHODS: A national crowdsourcing resulted in 1264 urine samples consisting of 536 IC (513 female, 21 male, 2 unspecified), and 728 age-matched controls (318 female, 402 male, 8 unspecified) with corresponding patient-reported outcome (PRO) pain and symptom scores. In addition, 296 urine samples were collected at three academic centers: 78 IC (71 female, 7 male) and 218 controls (148 female, 68 male, 2 unspecified). Urinary cytokine biomarker levels were determined using Luminex assay. A machine learning predictive classification model, termed the Interstitial Cystitis Personalized Inflammation Symptom (IC-PIS) Score, that utilizes PRO and cytokine levels, was generated and compared to a challenger model. RESULTS: The top-performing model using biomarker measurements and PROs (area under the curve [AUC]=0.87) was a support vector classifier, which scored better at predicting IC than PROs alone (AUC=0.83). While biomarkers alone (AUC=0.58) did not exhibit strong predictive performance, their combination with PROs produced an improved predictive effect. CONCLUSION: IC-PIS represents a novel classification model designed to enhance the diagnostic accuracy of IC/bladder pain syndrome by integrating PROs and urine biomarkers. The innovative approach to sample collection logistics, coupled with one of the largest crowdsourced biomarker development studies utilizing ambient shipping methods across the US, underscores the robustness and scalability of our findings.

Genomic hotspots for adaptation: the population genetics of Müllerian mimicry in Heliconius erato.

Wing pattern evolution in Heliconius butterflies provides some of the most striking examples of adaptation by natural selection. The genes controlling pattern variation are classic examples of Mendelian loci of large effect, where allelic variation causes large and discrete phenotypic changes and is responsible for both convergent and highly divergent wing pattern evolution across the genus. We characterize nucleotide variation, genotype-by-phenotype associations, linkage disequilibrium (LD), and candidate gene expression patterns across two unlinked genomic intervals that control yellow and red wing pattern variation among mimetic forms of Heliconius erato. Despite very strong natural selection on color pattern, we see neither a strong reduction in genetic diversity nor evidence for extended LD across either patterning interval. This observation highlights the extent that recombination can erase the signature of selection in natural populations and is consistent with the hypothesis that either the adaptive radiation or the alleles controlling it are quite old. However, across both patterning intervals we identified SNPs clustered in several coding regions that were strongly associated with color pattern phenotype. Interestingly, coding regions with associated SNPs were widely separated, suggesting that color pattern alleles may be composed of multiple functional sites, conforming to previous descriptions of these loci as "supergenes." Examination of gene expression levels of genes flanking these regions in both H. erato and its co-mimic, H. melpomene, implicate a gene with high sequence similarity to a kinesin as playing a key role in modulating pattern and provides convincing evidence for parallel changes in gene regulation across co-mimetic lineages. The complex genetic architecture at these color pattern loci stands in marked contrast to the single casual mutations often identified in genetic studies of adaptation, but may be more indicative of the type of genetic changes responsible for much of the adaptive variation found in natural populations.

Comparing online crowdsourcing with clinic patient enrollment: Findings from the IP4IC Study on interstitial cystitis/bladder pain syndrome.

Introduction: Interstitial cystitis/bladder pain syndrome (IC/BPS) manifests as urinary symptoms including urgency, frequency, and pain. The IP4IC Study aimed to establish a urine-based biomarker score for diagnosing IC/BPS. To accomplish this objective, we investigated the parallels and variances between patients enrolled via physician/hospital clinics and those recruited through online crowdsourcing. Methods: Through a nationwide crowdsource effort, we collected surveys from patients with history of IC/BPS. Study participants were asked to complete the validated instruments of Interstitial Cystitis Symptom Index (ICSI) and Interstitial Cystitis Problem Index (ICPI), as well as provide demographic information. We then compared the survey responses of patients recruited through crowdsourcing with those recruited from three specialized tertiary care urology clinics engaged in clinical research. Results: Survey responses of 1300 participants were collected from all 50 states of the USA via crowdsourcing and 319 from a clinical setting. ICSI and ICPI were similar for IC/BPS patients diagnosed by the physicians in clinic and self-reported by subjects via crowdsourcing stating they have a history of previous physician diagnosis of IC/BPS. Surprisingly, ICSI and ICPI were significantly lower in crowdsourced control than in-clinic control subjects. Conclusion: The IP4IC Study provides valuable insights into the similarities and differences between patients recruited through clinics and those recruited through online crowdsourcing. There were no significant differences in disease symptoms among these groups. Individuals who express an interest in digital health research and self-identify as having been previously diagnosed by physicians with IC/BPS can be regarded as reliable candidates for crowdsourcing research.

A Mesozoic fossil lagerstätte from 250.8 million years ago shows a modern-type marine ecosystem.

Finely preserved fossil assemblages (lagerstätten) provide crucial insights into evolutionary innovations in deep time. We report an exceptionally preserved Early Triassic fossil assemblage, the Guiyang Biota, from the Daye Formation near Guiyang, South China. High-precision uranium-lead dating shows that the age of the Guiyang Biota is 250.83 +0.07/-0.06 million years ago. This is only 1.08 ± 0.08 million years after the severe Permian-Triassic mass extinction, and this assemblage therefore represents the oldest known Mesozoic lagerstätte found so far. The Guiyang Biota comprises at least 12 classes and 19 orders, including diverse fish fauna and malacostracans, revealing a trophically complex marine ecosystem. Therefore, this assemblage demonstrates the rapid rise of modern-type marine ecosystems after the Permian-Triassic mass extinction.

Modulation of bladder afferent signals in normal and spinal cord-injured rats by purinergic P2X3 and P2X2/3 receptors.

OBJECTIVE: To evaluate the role of bladder sensory purinergic P2X3 and P2X2/3 receptors on modulating the activity of lumbosacral neurones and urinary bladder contractions in vivo in normal or spinal cord-injured (SCI) rats with neurogenic bladder overactivity. MATERIALS AND METHODS: SCI was induced in female rats by complete transection at T8-T9 and experiments were performed 4 weeks later, when bladder overactivity developed. Non-transected rats were used as controls (normal rats). Neural activity was recorded in the dorsal horn of the spinal cord and field potentials were acquired in response to intravesical pressure steps via a suprapubic catheter. Field potentials were recorded under control conditions, after stimulation of bladder mucosal purinergic receptors with intravesical ATP (1 mm), and after intravenous injection of the P2X3/P2X2/3 antagonist AF-353 (10 mg/kg and 20 mg/kg). Cystometry was performed in urethane-anaesthetised rats intravesically infused with saline. AF-353 (10 mg/kg) was systemically applied after baseline recordings; the rats also received a second dose of AF-353 (20 mg/kg). Changes in the frequency of voiding (VC) and non-voiding (NVC) contractions were evaluated. RESULTS: SCI rats had significantly higher frequencies for field potentials and NVC than NL rats. Intravesical ATP increased field potential frequency in control but not SCI rats, while systemic AF-353 significantly reduced this parameter in both groups. AF-353 also reduced the inter-contractile interval in control but not in SCI rats; however, the frequency of NVC in SCI rats was significantly reduced. CONCLUSION: The P2X3/P2X2/3 receptors on bladder afferent nerves positively regulate sensory activity and NVCs in overactive bladders.

A Cost, Time, and Demographic Analysis of Participant Recruitment and Urine Sample Collection Through Social Media Optimization.

INTRODUCTION: Clinical research can be expensive and time consuming due to high associated costs and/or duration of the study. We hypothesized that urine sample collection using online recruitment and engagement of research participants via social medial has the potential to reach a large population in a small timeframe, at a reasonable cost. METHODS: We performed a retrospective cost analysis of a cohort study comparing cost per sample and time per sample for both online and clinically recruited participants for urine sample collection. During this time, cost data were collected based on study associated costs from invoices and budget spreadsheets. The data were subsequently analyzed using descriptive statistics. RESULTS: Each sample collection kit contained 3 urine cups, 1 for the disease sample and 2 for control samples. Out of the 3,576 (1,192 disease + 2,384 control) total sample cups mailed, 1,254 (695 control) samples were returned. Comparatively, the 2 clinical sites collected 305 samples. Although the initial startup cost of online recruitment was higher, cost per sample for online recruited was found to be $81.45 compared to $398.14 for clinic sample. CONCLUSIONS: We conducted a nationwide, contactless, urine sample collection through online recruitment in the midst of the COVID-19 pandemic. Results were compared with the samples collected in the clinical setting. Online recruitment can be utilized to collect urine samples rapidly, efficiently, and at a cost per sample that was 20% of an in-person clinic, and without risk of COVID-19 exposure.

Effects of 100 and 300 units of onabotulinum toxin A on lower urinary tract symptoms of benign prostatic hyperplasia: a phase II randomized clinical trial.

PURPOSE: We conducted a 2-stage, multicenter, double-blind, randomized phase II clinical trial of 100 and 300 unit doses of onabotulinum toxin A to treat the lower urinary tract symptoms of benign prostatic hyperplasia. MATERIALS AND METHODS: Men 50 years old or older with clinically diagnosed benign prostatic hyperplasia, American Urological Association symptom index 8 or greater, maximum urinary flow rate less than 15 ml per second, voided volume 125 ml or greater, and post-void residual 350 ml or less were randomized to prostatic transrectal injection of 100 or 300 units of onabotulinum toxin A. The primary outcome was at least 30% improvement from baseline to 3 months in American Urological Association symptom index and/or maximum urinary flow rate and safety. The men were followed for 12 months. RESULTS: A total of 134 men were randomized and treated (68 with 100 units, 66 with 300 units), with 131 assessed at 3 months and 108 assessed at 12 months. Each dose met the 3-month primary outcome criteria. In the 100 unit arm the mean baseline American Urological Association symptom index of 18.8 decreased by 7.1 and 6.9 at 3 and 12 months, respectively. In the 300 unit arm the baseline of 19.5 decreased by 8.9 and 7.1, respectively. In the 100 unit arm the mean baseline maximum urinary flow rate of 10.0 ml per second increased by 2.5 and 2.2, respectively, and in the 300 unit arm the baseline of 9.6 increased by 2.6 and 2.3, respectively. CONCLUSIONS: The intraprostatic injection of 100 or 300 units of onabotulinum toxin A passed predetermined criteria for treatment efficacy and safety, and a randomized trial with either dose is warranted. The 100 unit dose may be preferable due to similar efficacy with reduced costs and adverse effects.

Central inhibitory effect of intravesically applied botulinum toxin A in chronic spinal cord injury.

AIMS: We evaluated a putative central inhibitory effect of intravesical botulinum toxin A (BoNT-A) on the activity of lumbosacral spinal neurons in a chronic spinal cord injury (SCI) model of bladder overactivity. METHODS: Female Sprague-Dawley rats underwent T8 spinal cord transection. Four weeks later, once overactive neuropathic detrusor pathways had developed, the animals underwent intravesical instillation with either saline (1 ml) or BoNT-A (Botox®, 20 U/1 ml) for 1 hr. Two days later, the rats then completed a cystometric evaluation prior to spinal cord harvest. Sections from the L4-S1 spinal cord segments were examined for the total number of c-fos immunoreactive cells. RESULTS: Comparison of the saline and BoNT-A treated groups showed a significant decrease in L6 (i.e., 67%, P < 0.001) and S1 (i.e., 47%, P < 0.01) c-fos expression (43%) in BoNT-A treated rats compared to saline controls. Cystometrogram studies revealed that the frequency of non-voiding bladder contractions was reduced by 73% (P < 0.05) in BoNT-A compared to saline treated rats. No change in the frequency of voiding bladder contractions or amplitude of bladder contraction was observed between the saline and BoNT-A treated groups. CONCLUSION: In a SCI model of bladder overactivity, intravesical BoNT-A significantly inhibits the response of bladder afferent activated lumbosacral neurons without significantly impairing efferent bladder function.

Exceptional fossil assemblages confirm the existence of complex Early Triassic ecosystems during the early Spathian.

The mass extinction characterizing the Permian/Triassic boundary (PTB; ~ 252 Ma) corresponds to a major faunal shift between the Palaeozoic and the Modern evolutionary fauna. The temporal, spatial, environmental, and ecological dynamics of the associated biotic recovery remain highly debated, partly due to the scarce, or poorly-known, Early Triassic fossil record. Recently, an exceptionally complex ecosystem dated from immediately after the Smithian/Spathian boundary (~ 3 myr after the PTB) was reported: the Paris Biota (Idaho, USA). However, the spatiotemporal representativeness of this unique assemblage remained questionable as it was hitherto only reported from a single site. Here we describe three new exceptionally diverse assemblages of the same age as the Paris Biota, and a fourth younger one. They are located in Idaho and Nevada, and are taxonomic subsets of the Paris Biota. We show that the latter covered a region-wide area and persisted at least partially throughout the Spathian. The presence of a well-established marine fauna such as the Paris Biota, as soon as the early Spathian, indicates that the post-PTB biotic recovery and the installation of complex ecosystems probably took place earlier than often assumed, at least at a regional scale.

Removal of urothelium affects bladder contractility and release of ATP but not release of NO in rat urinary bladder.

BACKGROUND: The objective of our work was to investigate both the contractile function and the release of ATP and NO from strips of bladder tissue after removal of the urothelium. METHODS: The method of removal was a gentle swabbing motion rather than a sharp surgical cutting to separate the urothelium from the smooth muscle. The contractile response and ATP and NO release were measured in intact as well as on swabbed preparations. The removal of the urothelial layer was affirmed microscopically. RESULTS: After the swabbing, the smaller contractions were evoked by electrical as well as by chemical stimulation (50 microM carbachol or 50 microM alpha, beta meATP). Electrical stimulation, carbachol and substance P (5 microM) evoked lower release of ATP in the swabbed strips than in intact strips. Although release of NO evoked by electrical stimulation or substance P was not changed, release of NO evoked by carbachol was significantly less in the swabbed preparations. CONCLUSION: Since swabbing removes only the urothelium, the presence of the suburothelial layer may explain the difference between our findings and those of others who found an increase in contractility. Evoked release of ATP is reduced in swabbed strips, indicating that ATP derives solely from the urothelium. On the other hand, electrical stimulation and substance P evoke identical degrees of NO release in both intact and swabbed preparations, suggesting that NO can be released from the suburothelium. Conversely, carbachol-induced release of NO is lower in swabbed strips, implying that the cholinergic receptors (muscarinic or nicotinic) are located in the upper layer of the urothelium.

Does strong linkage disequilibrium guarantee redundant association results?

A substantial amount of effort has been expended recently towards the identification and evaluation of tag single nucleotide polymorphisms; markers that, due to linkage disequilibrium (LD) patterns in the genome, are able to act as "proxies" for other polymorphic sites. As such, these tag markers are assumed to capture, on their own, a large proportion of the genetic variation contributed by a much greater number of polymorphic sites. One important consequence of this is the potential ability to reduce the cost of genotyping in an association study without a corresponding loss of power. This application carries an implicit assumption that strong LD between markers implies high correlation between the accompanying association test results, so that once a tag marker is evaluated for association, its outcome will be representative of all the other markers for which it serves as proxy. We examined this assumption directly. We find that in the null hypothesis situation, where there is no association between the markers and the phenotype, the relationship between LD and the correlation between association test outcomes is clear, though it is not always ideal. In the alternative case, when genetic association does exist in the region, the relationship becomes much more complex. Here, reasonably high LD between markers does not necessarily imply that the association test result of one marker is a direct substitute for that of the other. In these cases, eliminating one of these markers from the set to be genotyped in an association study will lead to a reduction in overall power.

The molecular basis for relative physiological functionality of the ADP/ATP carrier isoforms in Saccharomyces cerevisiae.

AAC2 is one of three paralogs encoding mitochondrial ADP/ATP carriers in the yeast Saccharomyces cerevisiae, and because it is required for respiratory growth it has been the most extensively studied. To comparatively examine the relative functionality of Aac1, Aac2, and Aac3 in vivo, the gene encoding each isoform was expressed from the native AAC2 locus in aac1Delta aac3Delta yeast. Compared to Aac2, Aac1 exhibited reduced capacity to support growth of yeast lacking mitochondrial DNA or of yeast lacking the ATP/Mg-P(i) carrier, both conditions requiring ATP import into the mitochondrial matrix through the ADP/ATP carrier. Sixteen AAC1/AAC2 chimeric genes were constructed and analyzed to determine the key differences between residues or sections of Aac1 and Aac2. On the basis of the growth rate differences of yeast expressing different chimeras, the C1 and M2 loops of the ADP/ATP carriers contain divergent residues that are responsible for the difference(s) between Aac1 and Aac2. One chimeric gene construct supported growth on nonfermentable carbon sources but failed to support growth of yeast lacking mitochondrial DNA. We identified nine independent intragenic mutations in this chimeric gene that suppressed the growth phenotype of yeast lacking mitochondrial DNA, identifying regions of the carrier important for nucleotide exchange activities.

Increased basement membrane thickness, pericyte ghosts, and loss of retinal thickness and cells in dopamine beta hydroxylase knockout mice.

Diabetes can cause damage to sympathetic nerves, and we have previously shown that experimental sympathectomy can produce capillary abnormalities in the retina similar to those seen in early diabetes. We postulate that the diabetes-induced loss of the sympathetic system, and at least in part the sympathetic neurotransmitter norepinephrine (NE), contributes to the development of retinal vascular and neural abnormalities in diabetes. Thus, we predict that non-diabetic animals that lack NE will develop microvascular and neural changes that are similar to those that are characteristic of diabetic retinopathy. To test this, retinas from non-diabetic dopamine beta hydroxylase (Dbh, Dbh(-/-)) knockout mice and their littermate controls were assessed for diabetic-like capillary and neural changes at 5 months of age. Genetic deletion of Dbh resulted in a significant decrease in retinal thickness and number of cells in the retinal ganglion cell layer (central retinal region). In addition, the number of pericyte ghosts and the basement membrane of retinal capillaries were significantly increased in the Dbh(-/-) mice. These results provide evidence that loss of sympathetic neurotransmission may contribute to the microvascular and neural changes of diabetic retinopathy. Restoration of sympathetic neurotransmission may be a new target for therapeutic intervention to inhibit the early phases of diabetic retinopathy.