Theranostic Trigger-Responsive Carbon Monoxide-Generating Microbubbles.

Carbon monoxide (CO) is a gaseous signaling molecule that modulates inflammation, cell survival, and recovery after myocardial infarction. However, handling and dosing of CO as a compressed gas are difficult. Here, light-triggerable and magnetic resonance imaging (MRI)-detectable CO release from dimanganese decacarbonyl (CORM-1) are demonstrated, and the development of CORM-1-loaded polymeric microbubbles (COMB) is described as an ultrasound (US)- and MRI-imageable drug delivery platform for triggerable and targeted CO therapy. COMB are synthesized via a straightforward one-step loading protocol, present a narrow size distribution peaking at 2 µm, and show excellent performance as a CORM-1 carrier and US contrast agent. Light irradiation of COMB induces local production and release of CO, as well as enhanced longitudinal and transversal relaxation rates, enabling MRI monitoring of CO delivery. Proof-of-concept studies for COMB-enabled light-triggered CO release show saturation of hemoglobin with CO in human blood, anti-inflammatory differentiation of macrophages, reduction of hypoxia-induced reactive oxygen species (ROS) production, and inhibition of ischemia-induced apoptosis in endothelial cells and cardiomyocytes. These findings indicate that CO-generating MB are interesting theranostic tools for attenuating hypoxia-associated and ROS-mediated cell and tissue damage in cardiovascular disease.

Clinical outcomes after one anastomosis gastric bypass versus sleeve gastrectomy in super-super-obese patients.

BACKGROUND: Bariatric surgery in super-super-obese (SSO) patients remains a continuous challenge due to intraabdominal fat masses, higher liver volume and existing comorbidities. A convenient procedure in SSO patients is one anastomosis gastric bypass (OAGB). The aim of this study was to compare the outcome of SSO patients undergoing OAGB in comparison to laparoscopic sleeve gastrectomy (LSG). METHODS: We retrospectively reviewed data from SSO patients who underwent OAGB and LSG in our institution between 2008 and 2020. Primary endpoints included percentage total body weight loss and percentage BMI loss at 12, 24, and 36 months after the operation. Secondary endpoints were perioperative complications, procedure length, length of hospital stay and outcome of comorbidities. RESULTS: 243 patients were included in this study. 93 patients underwent LSG and 150 underwent OAGB. At any of the time points evaluated, weight loss in patients after OAGB was greater than in LSG patients, while procedure length was significantly shorter for OAGB than LSG (81.4 vs. 92.1 min, p-value < 0.001). Additionally, mean length of hospital stay was shorter in the OAGB group (3.4 vs. 4.5 days, p-value < 0.001). There were more severe complications (Clavien-Dindo ≥ 3a) in the LSG group (11.8% vs 2.7%, p-value = 0.005). CONCLUSION: In this retrospective analysis, OAGB was superior to LSG in terms of weight loss in SSO patients. Procedure length and hospital stay were shorter after OAGB in comparison to LSG and there were fewer severe complications. OAGB can therefore be regarded a safe and effective treatment modality for SSO patients.

Roux-en-Y Versus One Anastomosis Gastric Bypass as Redo-Operations Following Sleeve Gastrectomy: A Retrospective Study.

BACKGROUND: Aim of this study was to improve knowledge about the best conversional bariatric procedure following sleeve gastrectomy (SG). METHODS: Data of conversional Roux-en-Y gastric bypass (RYGB) and of one anastomosis gastric bypass (OAGB) after SG were collected prospectively and analyzed retrospectively. Weight loss parameters, gastroesophageal reflux disease (GERD) and comorbidities outcomes were recorded. RESULTS: Total of 123 patients (90 female, mean age 44 ± 0.9 years, mean body mass index (BMI) 42 ± 0.8 kg/m2) had either RYGB (n = 68) or OAGB (n = 55). Perioperative mortality was zero. Mean surgery time was significantly shorter for OAGB (168 ± 7.2 vs. 201 ± 6.8 min). Perioperative complication rates were not significantly (ns) different between RYGB and OAGB. Total body weight loss (TBWL) in RYGB and OAGB was 18 ± 2.2% and 18 ± 1.9% (12 months) and 18 ± 3.0% and 23 ± 2.6% (24 months; ns), respectively. Length of (individualized) biliopancreatic limb (BPL) correlated significantly with weight loss. Remission rates after 12 months of RYGB and OAGB for arterial hypertension (aHt) were 89% and 92%, for obstructive sleep apnea (OSAS) 56% and 82%, for Type 2 diabetes mellitus (T2DM) 100% and 92%, for osteoarthritis 64% and 85% and for GERD 89% versus 87% (ns), respectively. Nutritional deficiencies were comparable in RYGB (n = 11) and OAGB (n = 14) group (ns). CONCLUSION: Both RYGB and OAGB are effective conversional procedures after SG, leading to comparable TBWL, BMI-loss and high remission rates of comorbidities including GERD. Significantly shorter operation times were in favor of OAGB. BPL, which was longer in OAGB was significantly related to higher %TBWL and %BMI-loss compared to RYGB.

Development of a tailor-made surgical online learning platform, ensuring surgical education in times of the COVID19 pandemic.

BACKGROUND: During the worldwide COVID-19 pandemic, the quality of surgical education experiences sudden major restrictions. Students' presence in the operating theater and on wards is reduced to a bare minimum and face-to-face teaching is diminished. Aim of this study was therefore to evaluate alternative but feasible educational concepts, such as an online-only-platform for undergraduates. OBJECTIVE: A new online platform for undergraduate surgical education was implemented. A virtual curriculum for online-only education was designed. METHODS: A video-based online platform was designed. Following this, a cohort of medical students participating in a (voluntary) surgical course was randomized into a test and control group. Prior to conducting a written exam, students in the test group prepared using the video platform. Students in the control group prepared with standard surgical text books. Results of the exam were used to compare educational means. RESULTS: Students in the test group preparing through the video-based online platform reached significantly higher scores in the written exams (p = 0.0001) than students of the control group. A trend towards reduced preparation time that did not reach statistical significance was detectable in the test group (p = 0.090). Scores of "perceived workload" and "desire to become a surgeon" offered no differences between the groups. (p = 0.474 and 1.000). CONCLUSIONS: An online-only, virtual curriculum proved feasible for surgical education in undergraduates. While blended learning concepts were applied in both groups, only the test group had access to case-based videos of surgical procedures and scored significantly better in the written exams. Thus, video-based virtual education offers a realistic alternative to face-to-face teaching or conventional text books in times of restricted access to the operating theatre.

Operative Time, Age, and Serum Albumin Predict Surgical Morbidity After Laparoscopic Liver Surgery.

Background. Laparoscopic liver resection (LLR) has emerged as a considerable alternative to conventional liver surgery. However, the increasing complexity of liver resection raises the incidence of postoperative complications. The aim of this study was to identify risk factors for postoperative morbidity in a monocentric cohort of patients undergoing LLR. Methods. All consecutive patients who underwent LLR between 2015 and 2019 at our institution were analyzed for associations between complications with demographics and clinical and operative characteristics by multivariable logistic regression analyses. Results. Our cohort comprised 156 patients who underwent LLR with a mean age of 60.0 ± 14.4 years. General complications and major perioperative morbidity were observed in 19.9% and 9.6% of the patients, respectively. Multivariable analysis identified age>65 years (HR = 2.56; P = .028) and operation time>180 minutes (HR = 4.44; P = .001) as significant predictors of general complications (Clavien ≥1), while albumin<4.3 g/dl (HR = 3.66; P = .033) and also operative time (HR = 23.72; P = .003) were identified as predictors of major postoperative morbidity (Clavien ≥3). Conclusion. Surgical morbidity is based on patient- (age and preoperative albumin) and procedure-related (operative time) characteristics. Careful patient selection is key to improve postoperative outcomes after LLR.

Drug Loading in Poly(butyl cyanoacrylate)-Based Polymeric Microbubbles.

Microbubbles (MB) are routinely used ultrasound (US) contrast agents that have recently attracted increasing attention as stimuli-responsive drug delivery systems. To better understand MB-based drug delivery, we studied the role of drug hydrophobicity and molecular weight on MB loading, shelf-life stability, US properties, and drug release. Eight model drugs, varying in hydrophobicity and molecular weight, were loaded into the shell of poly(butyl cyanoacrylate) (PBCA) MB. In the case of drugs with progesterone as a common structural backbone (i.e., for corticosteroids), loading capacity and drug release correlated well with hydrophobicity and molecular weight. Conversely, when employing drugs with no structural similarity (i.e., four different fluorescent dyes), loading capacity and release did not correlate with hydrophobicity and molecular weight. All model drug-loaded MB formulations could be equally efficiently destroyed upon exposure to US. Together, these findings provide valuable insights on how the physicochemical properties of (model) drug molecules affect their loading and retention in and US-induced release from polymeric MB, thereby facilitating the development of drug-loaded MB formulations for US-triggered drug delivery.

Inhaled Argon Impedes Hepatic Regeneration after Ischemia/Reperfusion Injury in Rats.

Organoprotective effects of noble gases are subject of current research. One important field of interest is the effect of noble gases on hepatic regenerative capacity. For the noble gas argon, promising studies demonstrated remarkable experimental effects in neuronal and renal cells. The aim of this study was to investigate the effects of argon on the regenerative capacity of the liver after ischemia/reperfusion injury (IRI). Male, Sprague-Dawley rats underwent hepatic IRI by clamping of the hepatic artery. Expression of hepatoproliferative genes (HGF, IL-1ß, IL-6, TNF), cell cycle markers (BrdU, TUNEL, Ki-67), and liver enzymes (ALT, AST, Bilirubin, LDH) were assessed 3, 36, and 96 h after IRI. Expression of IL-1ß and IL-6 was significantly higher after argon inhalation after 36 h (IL-1ß 5.0 vs. 8.7 fold, p = 0.001; IL-6 9.6 vs. 19.1 fold, p = 0.05). Ki-67 was higher in the control group compared to the argon group after 36 h (214.0 vs. 38.7 positive cells/1000 hepatocytes, p = 0.045). Serum levels of AST and ALT did not differ significantly between groups. Our data indicate that argon inhalation has detrimental effects on liver regeneration after IRI as measured by elevated levels of the proinflammatory cytokines IL-1ß and IL-6 after 36 h. In line with these results, Ki-67 is decreased in the argon group, indicating a negative effect on liver regeneration in argon inhalation.

Dystrophin is expressed in smooth muscle and afferent nerve fibers in the rat urinary bladder.

INTRODUCTION: With increasing life expectancy, comorbidities become overt in Duchenne muscular dystrophy (DMD). Although micturition problems are common, bladder function is poorly understood in DMD. We studied dystrophin expression and multiple isoform involvement in the bladder during maturation to gain insights into their roles in micturition. METHODS: Dystrophin distribution was evaluated in rat bladders by immunohistochemical colocalization with smooth muscle, interstitial, urothelial, and neuronal markers. Protein levels of Dp140, Dp71, and smooth muscle were quantitated by Western blotting of neonatal to adult rat bladders. RESULTS: Dystrophin colocalized with smooth muscle cells and afferent nerve fibers. Dp71 was expressed two- to threefold higher compared with Dp140, independently of age. Age-related muscle mass changes did not influence isoform expression levels. DISCUSSION: Dystrophin is expressed in smooth muscle cells and afferent nerve fibers in the urinary bladder, which underscores that micturition problems in DMD may have not solely a myogenic but also a neurogenic origin. Muscle Nerve 60: 202-210, 2019.

Accelerated cognitive decline in a rodent model for temporal lobe epilepsy.

OBJECTIVE: Cognitive impairment is frequently observed in patients with temporal lobe epilepsy. It is hypothesized that cumulative seizure exposure causes accelerated cognitive decline in patients with epilepsy. We investigated the influence of seizure frequency on cognitive decline in a rodent model for temporal lobe epilepsy. METHODS: Neurobehavioral assessment was performed before and after surgery, after the induction of self-sustaining limbic status epilepticus (SSLSE), and in the chronic phase in which rats experienced recurrent seizures. Furthermore, we assessed potential confounders of memory performance. RESULTS: Rats showed a deficit in spatial working memory after the induction of the SSLSE, which endured in the chronic phase. A progressive decline in recognition memory developed in SSLSE rats. Confounding factors were absent. Seizure frequency and also the severity of the status epilepticus were not correlated with the severity of cognitive deficits. SIGNIFICANCE: The effect of the seizure frequency on cognitive comorbidity in epilepsy has long been debated, possibly because of confounders such as antiepileptic medication and the heterogeneity of epileptic etiologies. In an animal model of temporal lobe epilepsy, we showed that a decrease in spatial working memory does not relate to the seizure frequency. This suggests for other mechanisms are responsible for memory decline and potentially a common pathophysiology of cognitive deterioration and the occurrence and development of epileptic seizures. Identifying this common denominator will allow development of more targeted interventions treating cognitive decline in patients with epilepsy. The treatment of interictal symptoms will increase the quality of life of many patients with epilepsy.

Students and physicians differ in perception of quality of life in patients with tumors of the upper gastrointestinal tract.

Health-related quality of life (HRQoL) has recently gained importance as treatment options for tumors of the upper GI tract lead to improved long-term survival. HRQoL is often estimated by physicians even though their reliability and the impact of outside factors such as contact time and level of medical education is unclear. Therefore, in this study we investigated the correlation between physicians', students', and patients' assessment of HRQoL. 54 patients presenting with tumors of the upper GI tract were included and asked to fill out the standardized HRQoL questionnaires EORTC QLQ-C30 and QLQ-OG25. Attending physicians and medical students filled out the same questionnaires through estimation of patients' HRQoL. Correlation was assessed through Pearson's and Kendall's τb coefficients. Physicians' and patients' assessments correlated for one out of six of the functional and a third of the symptom scores. Students' and patients' assessments correlated for one third of the functional and two thirds of the symptom scores. Students tended to underestimate patients' symptom burden while physicians tended to overestimate it. Physicians failed to correctly assess several pathognomonic symptoms in this study. Students showed higher correlation with patients' symptoms than physicians. Even so, this adds to mounting evidence that shows the benefit of using patient-reported outcomes as a gold standard regarding HRQoL.

Insulin Resistance Is the Main Characteristic of Metabolically Unhealthy Obesity (MUO) Associated with NASH in Patients Undergoing Bariatric Surgery.

(1) Background: Metabolically healthy obesity (MHO) is a concept that applies to obese patients without any elements of metabolic syndrome (metS). In turn, metabolically unhealthy obesity (MUO) defines the presence of elements of metS in obese patients. The components of MUO can be divided into subgroups regarding the elements of inflammation, lipid and glucose metabolism and cardiovascular disease. MUO patients appear to be at greater risk of developing non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) compared to MHO patients. The aim of this study was to evaluate the influence of different MUO components on NAFLD and NASH in patients with morbid obesity undergoing bariatric surgery. (2) Methods: 141 patients undergoing bariatric surgery from September 2015 and October 2021 at RWTH Aachen university hospital (Germany) were included. Patients were evaluated pre-operatively for characteristics of metS and MUO (HbA1c, HOMA, CRP, BMI, fasting glucose, LDL, TG, HDL and the presence of arterial hypertension). Intraoperatively, a liver biopsy was taken from the left liver lobe and evaluated for the presence of NAFLD or NASH. In ordinal regression analyses, different factors were evaluated for their influence on NAFLD and NASH. (3) Results: Mean BMI of the patients was 52.3 kg/m2 (36-74.8, SD 8.4). Together, the parameters HbA1c, HOMA, CRP, BMI, fasting glucose, LDL, TG, HDL and the presence of arterial hypertension accounted for a significant amount of variance in the outcome, with a likelihood ratio of χ2 (9) = 41.547, p < 0.001, for predicting the presence of NASH. Only HOMA was an independent predictor of NASH (B = 0.102, SE = 0.0373, p = 0.007). Evaluation of steatosis showed a similar trend (likelihood ratio χ2 (9) = 40.272, p < 0.001). Independent predictors of steatosis were HbA1c (B = 0.833, SE = 0.343, p = 0.015) and HOMA (B = 0.136, SE = 0.039, p < 0.001). (4) Conclusions: The above-mentioned model, including components of MUO, was significant for diagnosing NASH in patients with morbid obesity undergoing bariatric surgery. Out of the different subitems, HOMA independently predicted the presence of NASH and steatosis, while HbA1c independently predicted steatosis and fibrosis. Taken together, the parameter of glucose metabolism appears to be more accurate for the prediction of NASH than the parameters of lipid metabolism, inflammation or the presence of cardiovascular disease.

Laparoscopic hepatectomy reduces postoperative complications and hospital stay in overweight and obese patients.

BACKGROUND: Laparoscopic liver surgery is currently considered the standard of care for various liver malignancies. However, studies focusing on perioperative outcome after laparoscopic hepatectomy (LH) in overweight patients are still sparse and its benefit compared to open hepatectomy (OH) is a matter of debate. AIM: To analyze postoperative outcomes in overweight [body mass index (BMI) over 25 kg/m²] and obese (BMI over 30 kg/m²) patients undergoing LH and compare postoperative outcome with patients undergoing OH. METHODS: Perioperative data of 68 overweight (BMI over 25 kg/m²) including a subcohort of obese (BMI over 30 kg/m²) patients (n = 27) who underwent LH at our institution between 2015 and 2019 were retrospectively analyzed regarding surgical outcome and compared to an equal number of patients undergoing OH. RESULTS: The mean BMI was 29.8 ± 4.9 kg/m2 in the LH group and 29.7 ± 3.6 kg/m2 in the OH group with major resections performed in 20.6% (LH) and 26.5% (OH) of cases, respectively. Operative time (194 ± 88 min vs 275 ± 131 min; P < 0.001) as well as intensive care (0.8 ± 0.7 d vs 1.1 ± 0.8 d; P = 0.031) and hospital stay (7.3 ± 3.6 d vs 15.7 ± 13.5 d; P < 0.001) were significant shorter in the LH group. Also, overall complications (20.6% vs 45.6%; P = 0.005) and major complications (1.5% vs 14.7%, P = 0.002) were observed less frequently after LH. An additional investigation analyzing the subgroup of obese patients who underwent LH (n = 27) and OH (n = 29) showed a shorter operative time (194 ± 81 min vs 260 ± 137 min; P = 0.009) and a reduced length of hospitalization (7.7 ± 4.3 d vs 17.2 ± 17 d; P < 0.001) but no difference in postoperative complications or overall cost. CONCLUSION: LH is safe and cost-effective in overweight and obese patients. Furthermore, LH is significantly associated with fewer postoperative complications and reduced hospital stay compared to OH in these patients.

Combined Liver and Inferior Vena Cava Resection for Malignancies Is Safe and Feasible in a Group of High-Risk Patients.

BACKGROUND AND METHODS: Tumors infiltrating the inferior caval vein (ICV) have been considered irresectable in the past due to high perioperative risks. Consequently, the only treatment option for these patients was best supportive care, which resulted in reduced survival. Advancements in surgical techniques have since evolved, such that combined resections of the ICV and the hepatic malignancy are being performed. The aim of this study was the evaluation of the long-term outcomes (e.g., survival) and short-term risks of this procedure. In this single-center, retrospective cohort study (n = 24), we evaluated surgical and oncological outcome for patients undergoing hepatic surgery for oncological indications in combination with resections of the ICV. In addition, we investigated which factors are associated with survival. RESULTS: First, we showed that perioperative mortality is as low as 4.1%. Second, we showed that perioperative co-morbidities are acceptable for this type of advanced hepatobiliary surgery. Third, the reconstruction of the ICV by means of a patch was superior in terms of survival compared to other types of reconstructions. This finding was independent of the type or the aggressiveness of tumor or the resections status. DISCUSSION: In our cohort, many patients had undergone (multiple) preceding visceral surgical interventions or underwent multi-visceral surgery. Despite the medical complexity, survival was encouraging in this cohort, offering novel treatment modalities with a low risk of severe morbidities.

Baseline Presence of NAFLD Predicts Weight Loss after Gastric Bypass Surgery for Morbid Obesity.

BACKGROUND: Bariatric surgery is a widely used treatment for morbid obesity. Prediction of postoperative weight loss currently relies on prediction models, which mostly overestimate patients' weight loss. Data about the influence of Non-alcoholic fatty liver disease (NAFLD) on early postoperative weight loss are scarce. METHODS: This prospective, single-center cohort study included 143 patients receiving laparoscopic gastric bypass surgery (One Anastomosis-Mini Gastric Bypass (OAGB-MGB) or Roux-en-Y Gastric Bypass (RYGB)). Liver biopsies were acquired at surgery. NAFLD activity score (NAS) assigned patients to "No NAFLD", "NAFL" or "NASH". Follow up data were collected at 3, 6 and 12 months. RESULTS: In total, 49.7% of patients had NASH, while 41.3% had NAFL. Compared with the No NAFLD group, NAFL and NASH showed higher body-mass-index (BMI) at follow-up (6 months: 31.0 kg/m2 vs. 36.8 kg/m2 and 36.1 kg/m2, 12 months: 27.0 kg/m2 vs. 34.4 and 32.8 kg/m2) and lower percentage of total body weight loss (%TBWL): (6 months: 27.1% vs. 23.3% and 24.4%; 12 months: 38.5% vs. 30.1 and 32.6%). Linear regression of NAS points significantly predicts percentage of excessive weight loss (%EWL) after 6 months (Cologne-weight-loss-prediction-score). CONCLUSIONS: Histopathological presence of NAFLD might lead to inferior postoperative weight reduction after gastric bypass surgery. The mechanisms underlying this observation should be further studied.

Influence of MRI Examinations on Animal Welfare and Study Results.

OBJECTIVES: Magnetic resonance imaging (MRI) is considered to be well tolerated by laboratory animals. However, no systematic study has been performed yet, proving this assumption. Therefore, the aim of this study was to investigate the possible effects of longitudinal native and contrast-enhanced (CE) 1-T and 7-T MRI examinations on mouse welfare as well as 4T1 breast cancers progression and therapy response. MATERIAL AND METHODS: Forty-seven healthy and 72 breast cancer-bearing mice (4T1) were investigated. One-Tesla (ICON) and 7-T (Biospec) MRI measurements were performed thrice per week under isoflurane anesthesia in healthy BALB/c mice for 4 weeks and 3 times within 2 weeks in tumor-bearing animals. Animal welfare was examined by an observational score sheet, rotarod performance, heart rate measurements, and assessment of fecal corticosterone metabolites. Furthermore, we investigated whether CE-MRI influences the study outcome. Therefore, hemograms and organ weights were obtained, and 4T1 tumor growth, perfusion, immune cell infiltration, as well as response to the multikinase inhibitor regorafenib were investigated. Statistical comparisons between groups were performed using analysis of variance and Tukey or Bonferroni post hoc tests. RESULTS: Mice showed no alterations in the observational score sheet rating, rotarod performance, heart rate, and fecal corticosterone metabolites (P > 0.05) after repeated MRI at both field strengths. However, spleen weights were reduced in all healthy mouse groups that received isoflurane anesthesia (P < 0.001) including the groups investigated by 1-T and 7-T MRI (P = 0.02). Neither tumor progression nor response to the regorafenib treatment was affected by isoflurane anesthesia or CE-MRI monitoring. Furthermore, immunohistological tumor analysis did not indicate an effect of isoflurane and MRI on macrophage infiltration of tumors, perfusion of tumor vessels, and apoptotic cell rate (P > 0.05). CONCLUSIONS: Repeated MRI did not influence the welfare of mice and did not affect tumor growth and therapy response of 4T1 tumors. However, systemic immunological effects of isoflurane anesthesia need to be considered to prevent potential bias.

The Role of the Periaqueductal Gray Matter in Lower Urinary Tract Function.

The periaqueductal gray matter (PAG), as one of the mostly preserved evolutionary components of the brain, is an axial structure modulating various important functions of the organism, including autonomic, behavioral, pain, and micturition control. It has a critical role in urinary bladder physiology, with respect to storage and voiding of urine. The PAG has a columnar composition and has extensive connections with its cranially and caudally located components of the central nervous system (CNS). The PAG serves as the control tower of the detrusor and sphincter contractions. It serves as a bridge between the evolutionary higher decision-making brain centers and the lower centers responsible for reflexive micturition. Glutamatergic cells are the main operational neurons in the vlPAG, responsible for the reception and relay of the signals emerging from the bladder, to related brain centers. Functional imaging studies made it possible to clarify the activity of the PAG in voiding and filling phases of micturition, and its connections with various brain centers in living humans. The PAG may be affected in a wide spectrum of disorders, including multiple sclerosis (MS), migraine, stroke, Wernicke's encephalopathy, and idiopathic normal pressure hydrocephalus, all of which may have voiding dysfunction or incontinence, in certain stages of the disease. This emphasizes the importance of this structure for the basic understanding of voiding and storage disorders and makes it a potential candidate for diagnostic and therapeutic interventions.

Neuronal Activation in the Periaqueductal Gray Matter Upon Electrical Stimulation of the Bladder.

Reflexes, that involve the spinobulbospinal pathway control both storage and voiding of urine. The periaqueductal gray matter (PAG), a pontine structure is part of the micturition pathway. Alteration in this pathway could lead to micturition disorders and urinary incontinence, such as the overactive bladder symptom complex (OABS). Although different therapeutic options exist for the management of OABS, these are either not effective in all patients. Part of the pathology of OABS is faulty sensory signaling about the filling status of the urinary bladder, which results in aberrant efferent signaling leading to overt detrusor contractions and the sensation of urgency and frequent voiding. In order to identify novel targets for therapy (i.e., structures in the central nervous system) and explore novel treatment modalities such as neuromodulation, we aimed at investigating which areas in the central nervous system are functionally activated upon sensory afferent stimulation of the bladder. Hence, we designed a robust protocol with multiple readout parameters including immunohistological and behavioral parameters during electrical stimulation of the rat urinary bladder. Bladder stimulation induced by electrical stimulation, below the voiding threshold, influences neural activity in: (1) the caudal ventrolateral PAG, close to the aqueduct; (2) the pontine micturition center and locus coeruleus; and (3) the superficial layers of the dorsal horn, sacral parasympathetic nucleus and central canal region of the spinal cord. In stimulated animals, a higher voiding frequency was observed but was not accompanied by increase in anxiety level and locomotor deficits. Taken together, this work establishes a critical role for the vlPAG in the processing of sensory information from the urinary bladder and urges future studies to investigate the potential of neuromodulatory approaches for urological diseases.

Electrophysiological responses of the ventrolateral periaqueductal gray matter neurons towards peripheral bladder stimulation.

INTRODUCTION: Many of the currently available therapies for urinary incontinence target the peripheral autonomic system, despite many etiologies residing in the central nervous system. Following previous experiments that determined the ventrolateral column of the periaqueductal gray matter (vlPAG), to be the main afferent station of bladder sensory signals, we aimed for electrophysiological characterization of vlPAG neurons using single unit recording. METHODS: 15 rats were anesthetized and underwent implantation with electrodes at the dome and the neck of the bladder, to electrically stimulate the detrusor. After craniotomy, a glass micropipette was inserted in vlPAG to record neuronal action potentials. The detrusor was stimulated by a series of 20 Hz pulses, for a total duration of 50 s at an intensity of 2 mA, for each vlPAG neuron selected. Single unit recordings were performed on a total of 26 neurons. Confirmation of electrode position was made by iontophoretic ejection of Pontamine sky blue. RESULTS: The firing rate of vlPAG neurons decreased significantly during the stimulation period. Peristimulus time histogram (PSTH) analysis showed 24 out of 26 neurons to be unresponsive to stimulation. All recorded vlPAG neurons showed irregular firing patterns. CONCLUSIONS: The change in firing rate may point to an overall inhibitory influence of bladder stimulation on vlPAG neurons. These data suggest an inhibitory relay station at the vlPAG, before sensory bladder signals would affect pontine micturition center. The lack of the inhibitory effect on PSTH may be due to a longer interval between neuronal response and the stimulation.

Fornix deep brain stimulation induced long-term spatial memory independent of hippocampal neurogenesis.

Deep brain stimulation (DBS) is an established symptomatic treatment modality for movement disorders and constitutes an emerging therapeutic approach for the treatment of memory impairment. In line with this, fornix DBS has shown to ameliorate cognitive decline associated with dementia. Nonetheless, mechanisms mediating clinical effects in demented patients or patients with other neurological disorders are largely unknown. There is evidence that DBS is able to modulate neurophysiological activity in targeted brain regions. We therefore hypothesized that DBS might be able to influence cognitive function via activity-dependent regulation of hippocampal neurogenesis. Using stimulation parameters, which were validated to restore memory loss in a previous behavioral study, we here assessed long-term effects of fornix DBS. To do so, we injected the thymidine analog, 5-bromo-2'-deoxyuridine (BrdU), after DBS and perfused the animals 6.5 weeks later. A week prior to perfusion, memory performance was assessed in the water maze. We found that acute stimulation of the fornix improved spatial memory performance in the water maze when the probe trial was performed 1 h after the last training session. However, no evidence for stimulation-induced neurogenesis was found in fornix DBS rats when compared to sham. Our results suggest that fornix DBS improves memory functions independent of hippocampal neurogenesis, possibly through other mechanisms such as synaptic plasticity and acute neurotransmitter release.