Case series - COVID-19 is unlikely to affect male fertility: Results of histopathological and reverse transcriptase polymerase chain reaction analysis

INTRODUCTION

We aimed to analyze the testicular histopathology of men who died with active COVID-19 infection.

METHODS

We performed autopsy of eight consecutive men who died of COVID-19 pneumonia. Lung and testis tissue of all men were stained for SARS-CoV-2 nucleocapsid, ACE2 receptor immunohistochemistry (IHC). H&E was performed to assess for spermatogenesis and evidence of testicle tissue damage. Reverse transcriptase polymerase chain reaction (RTPCR) analysis for SARS-CoV-2 was performed on matched lung and bilateral testicular tissue samples from all men.

RESULTS

Patient age ranged from 50-79 years. SARS-CoV-2 viral RNA was detected by RTPCR in testis tissue in one man. All eight testicle specimens that underwent IHC for ACE2 receptor showed uniformly strong immunoreactivity against all testicle cell populations. By H&E, all testis specimens showed no inflammation, vascular thrombosis, vasculitis, or morphological evidence of viral changes. One case showed diminished but not absent spermatogenesis, consistent with patient age.

CONCLUSIONS

Our results suggest that SARS-CoV-2 is unlikely to affect male fertility. Contrary to all prior histological studies, our results showed no evidence of damage to reproductive tissues that might impair fertility.

Feminising hormone therapy reduces testicular ACE-2 receptor expression: Implications for treatment or prevention of COVID-19 infection in men

It has been proposed that men hospitalised with COVID-19 be treated with oestrogen or progesterone to improve COVID-19 outcomes. Transgender women (male-to-female) are routinely treated with oestrogen or oestrogen +progesterone for feminisation which provides a model for the effect of feminising hormones on testicular tissue. Our goal was to analyse differences in ACE-2 expression in testicles of trans-women taking oestrogen or oestrogen +progesterone. Orchiectomy specimens were collected from trans-women undergoing gender-affirming surgery, who were taking oestrogen or oestrogen+progesterone preoperatively. For controls, we used benign orchiectomy specimens from cis-gender men. All specimens were stained with H&E, Trichrome (fibrosis), insulin-like 3 antibody (Leydig cell) and ACE-2 IHC. Cells per high-powered field were counted by cell type (Leydig, Sertoli and Germ). Stain intensity was rated on a 0-2 scale. On immunohistochemistry staining for Leydig cells and ACE-2 staining, the oestrogen+progesterone cohort had fewer Leydig cells compared with controls. The oestrogen+progesterone cohort also had greater degree of tissue fibrosis compared with controls and the oestrogen cohort. This work supports the hopeful possibility that a short course of progesterone (or oestrogen+progesterone) could downregulate ACE-2 to protect men from COVID-19 infection.

Comparative liquid chromatography/tandem mass spectrometry lipidomics analysis of macaque heart tissue flash-frozen or embedded in optimal cutting temperature polymer (OCT): Practical considerations

RATIONALE

Biobanks of patient tissues have emerged as essential resources in biomedical research. Optimal cutting temperature compound (OCT) blends have shown to provide stability to the embedded tissue and are compatible with spectroscopic methods, such as infrared (IR) and Raman spectroscopy. Data derived from omics-methods are only useful if tissue damage caused by storage in OCT blends is minimal and well understood. In this context, we investigated the suitability of OCT storage for heart tissue destined for liquid chromatography/tandem mass spectrometry (LC/MS/MS) lipidomic studies.

METHODS

To determine the compatibility of OCT storage with LC/MS/MS lipidomics studies. The lipid profiles of macaque heart tissue snap-frozen in liquid nitrogen or stored in an OCT blend were evaluated.

RESULTS

We have evaluated a lipid extraction protocol suitable for OCT-embedded tissue that is compatible with LC/MS/MS. We annotated and evaluated the profiles of 306 lipid species from tissues stored in OCT or liquid nitrogen. For most of the lipid species (95.4%), the profiles were independent of the storage conditions. However, 4.6% of the lipid species; mainly plasmalogens, were affected by the storage method.

CONCLUSIONS

This study shows that OCT storage is compatible with LC-MS/MS lipidomics of heart tissue, facilitating the use of biobanked tissue samples for future studies.

Deleterious Effects of SARS-CoV-2 Infection on Human Pancreatic Cells

COVID-19 pandemic has infected more than 154 million people worldwide and caused more than 3.2 million deaths. It is transmitted by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and affects the respiratory tract as well as extra-pulmonary systems, including the pancreas, that express the virus entry receptor, Angiotensin-Converting Enzyme 2 (ACE2) receptor. Importantly, the endocrine and exocrine pancreas, the latter composed of ductal and acinar cells, express high levels of ACE2, which correlates to impaired functionality characterized as acute pancreatitis observed in some cases presenting with COVID-19. Since acute pancreatitis is already one of the most frequent gastrointestinal causes of hospitalization in the U.S. and the majority of studies investigating the effects of SARS-CoV-2 on the pancreas are clinical and observational, we utilized human iPSC technology to investigate the potential deleterious effects of SARS-CoV-2 infection on iPSC-derived pancreatic cultures containing endocrine and exocrine cells. Interestingly, iPSC-derived pancreatic cultures allow SARS-CoV-2 entry and establish infection, thus perturbing their normal molecular and cellular phenotypes. The infection increased a key cytokine, CXCL12, known to be involved in inflammatory responses in the pancreas. Transcriptome analysis of infected pancreatic cultures confirmed that SARS-CoV-2 hijacks the ribosomal machinery in these cells. Notably, the SARS-CoV-2 infectivity of the pancreas was confirmed in post-mortem tissues from COVID-19 patients, which showed co-localization of SARS-CoV-2 in pancreatic endocrine and exocrine cells and increased the expression of some pancreatic ductal stress response genes. Thus, we demonstrate that SARS-CoV-2 can directly infect human iPSC-derived pancreatic cells with strong supporting evidence of presence of the virus in post-mortem pancreatic tissue of confirmed COVID-19 human cases. This novel model of iPSC-derived pancreatic cultures will open new avenues for the comprehension of the SARS-CoV-2 infection and potentially establish a platform for endocrine and exocrine pancreas-specific antiviral drug screening.

Detection and Quantification of Myocardial Fibrosis Using Stain-Free Infrared Spectroscopic Imaging

CONTEXT.—

Myocardial fibrosis underpins a number of cardiovascular conditions and is difficult to identify with standard histologic techniques. Challenges include imaging, defining an objective threshold for classifying fibrosis as mild or severe, as well as understanding the molecular basis for these changes.

OBJECTIVE.—

To develop a novel, rapid, label-free approach to accurately measure and quantify the extent of fibrosis in cardiac tissue using infrared spectroscopic imaging.

DESIGN.—

We performed infrared spectroscopic imaging and combined that with advanced machine learning-based algorithms to assess fibrosis in 15 samples from patients belonging to the following 3 classes: (1) nonpathologic (control) donor hearts; (2) patients receiving transplant; and (3) tissue from patients undergoing implantation of ventricular assist device.

RESULTS.—

Our results show excellent sensitivity and accuracy for detecting myocardial fibrosis as demonstrated by high area under the curve of 0.998 in the receiver-operating characteristic curve measured from infrared imaging. Fibrosis of various morphologic subtypes are then demonstrated with virtually generated picrosirius red images, which show good visual and quantitative agreement (correlation coefficient = 0.92, ρ = 7.76 × 10-15) with stained images of the same sections. Underlying molecular composition of the different subtypes were investigated with infrared spectra showing reproducible differences presumably arising from differences in collagen subtypes and/or crosslinking.

CONCLUSIONS.—

Infrared imaging can be a powerful tool in studying myocardial fibrosis and gleaning insights into the underlying chemical changes that accompany it. Emerging methods suggest that the proposed approach is compatible with conventional optical microscopy and its consistency makes it translatable to the clinical setting for real-time diagnoses as well as for objective and quantitative research.

Seroprevalence of antibodies to SARS-CoV-2 in healthcare workers: a cross-sectional study

OBJECTIVE

We sought to determine the extent of SARS-CoV-2 seroprevalence and the factors associated with seroprevalence across a diverse cohort of healthcare workers.

DESIGN

Observational cohort study of healthcare workers, including SARS-CoV-2 serology testing and participant questionnaires.

SETTINGS

A multisite healthcare delivery system located in Los Angeles County.

PARTICIPANTS

A diverse and unselected population of adults (n=6062) employed in a multisite healthcare delivery system located in Los Angeles County, including individuals with direct patient contact and others with non-patient-oriented work functions.

MAIN OUTCOMES

Using Bayesian and multivariate analyses, we estimated seroprevalence and factors associated with seropositivity and antibody levels, including pre-existing demographic and clinical characteristics; potential COVID-19 illness-related exposures; and symptoms consistent with COVID-19 infection.

RESULTS

We observed a seroprevalence rate of 4.1%, with anosmia as the most prominently associated self-reported symptom (OR 11.04, p<0.001) in addition to fever (OR 2.02, p=0.002) and myalgias (OR 1.65, p=0.035). After adjusting for potential confounders, seroprevalence was also associated with Hispanic ethnicity (OR 1.98, p=0.001) and African-American race (OR 2.02, p=0.027) as well as contact with a COVID-19-diagnosed individual in the household (OR 5.73, p<0.001) or clinical work setting (OR 1.76, p=0.002). Importantly, African-American race and Hispanic ethnicity were associated with antibody positivity even after adjusting for personal COVID-19 diagnosis status, suggesting the contribution of unmeasured structural or societal factors.

CONCLUSION AND RELEVANCE

The demographic factors associated with SARS-CoV-2 seroprevalence among our healthcare workers underscore the importance of exposure sources beyond the workplace. The size and diversity of our study population, combined with robust survey and modelling techniques, provide a vibrant picture of the demographic factors, exposures and symptoms that can identify individuals with susceptibility as well as potential to mount an immune response to COVID-19.

Effect of Pneumatic Tubing System Transport on Platelet Apheresis Units

Platelet apheresis units are transfused into patients to mitigate or prevent bleeding. In a hospital, platelet apheresis units are transported from the transfusion service to the healthcare teams via two methods: a pneumatic tubing system (PTS) or ambulatory transport. Whether PTS transport affects the activity and utility of platelet apheresis units is unclear. We quantified the gravitational forces and transport time associated with PTS and ambulatory transport within our hospital. Washed platelets and supernatants were prepared from platelet apheresis units prior to transport as well as following ambulatory or PTS transport. For each group, we compared resting and agonist-induced platelet activity and platelet aggregate formation on collagen or von Willebrand factor (VWF) under shear, platelet VWF-receptor expression and VWF multimer levels. Subjection of platelet apheresis units to rapid acceleration/deceleration forces during PTS transport did not pre-activate platelets or their ability to activate in response to platelet agonists as compared to ambulatory transport. Platelets within platelet apheresis units transported via PTS retained their ability to adhere to surfaces of VWF and collagen under shear, although platelet aggregation on collagen and VWF was diminished as compared to ambulatory transport. VWF multimer levels and platelet GPIb receptor expression was unaffected by PTS transport as compared to ambulatory transport. Subjection of platelet apheresis units to PTS transport did not significantly affect the baseline or agonist-induced levels of platelet activation as compared to ambulatory transport. Our case study suggests that PTS transport may not significantly affect the hemostatic potential of platelets within platelet apheresis units.

Exploring the relationship between β-adrenergic receptor kinase-1 and physical symptoms in heart failure

BACKGROUND

The relationship between physical heart failure (HF) symptoms and pathophysiological mechanisms is unclear.

OBJECTIVE

To quantify the relationship between plasma β-adrenergic receptor kinase-1 (βARK1) and physical symptoms among adults with HF.

METHODS

We performed a secondary analysis of data collected from two studies of adults with HF. Plasma βARK1 was quantified using an enzyme-linked immunosorbent assay. Physical symptoms were measured with the HF Somatic Perception Scale (HFSPS). Generalized linear modeling was used to quantify the relationship between βARK1 and HFSPS scores.

RESULTS

The average age (n = 94) was 54.5 ± 13.1 years, 76.6% were male, and a majority (83.0%) had Class III or IV HF. βARK1 was significantly associated with HFSPS scores (β = 0.22 ± 0.10, p = 0.038), adjusting for other predictors of physical symptoms (model R² = 0.250, F(7, 70) = 3.34, p = 0.004).

CONCLUSIONS

Higher βARK1 is associated with worse physical HF symptoms, pinpointing a potential pathophysiologic underpinning.

Audit of GP Referrals for Tonsillectomy to the ENT Clinic Using Present HIQA Guidelines

Recurrent sore throat for possible tonsillectomy is the commonest clinical entity referred to the ENT outpatient department. The numbers involved represent a large clinical burden on the service. Not all of these patients require surgical intervention. Patients who fit the criteria for tonsillectomy are faced with two stage obstacles; the long waiting time until assessed by the Otolaryngologist at OPD and the time spent on long operative waiting lists. The aim of this study was to analyze the percentage of referred patients with sore throats requiring tonsillectomy versus those not needing surgery, using the present HIQA guidelines for this operation.

Endocardial Endothelial Dysfunction Progressively Disrupts Initially Anti then Pro-Thrombotic Pathways in Heart Failure Mice

Objective

An experimental model of endocardial thrombosis has not been developed and endocardial endothelial dysfunction in heart failure (HF) is understudied. We sought to determine whether disruption of the endothelial anti-coagulant activated protein C (APC) pathway in CREB_A133 HF mice promotes endocardial thrombosis in the acute decompensated phase of the disease, and whether alterations in von Willebrand factor (vWF) secretion from HF endocardium reduces thrombus formation as HF stabilizes.

Approach and results

Echocardiography was used to follow HF development and to detect endocardial thrombi in CREB_A133 mice. Endocardial thrombi incidence was confirmed with immunohistochemistry and histology. In early and acute decompensated phases of HF, CREB_A133 mice had the highest incidence of endocardial thrombi and these mice also had a shorter tail-bleeding index consistent with a pro-thrombotic milieu. Both APC generation, and expression of receptors that promote APC function (thrombomodulin, endothelial protein C receptor, protein S), were suppressed in the endocardium of acute decompensated HF mice. However, in stable compensated HF mice, an attenuation occurred for vWF protein content and secretion from endocardial endothelial cells, vWF-dependent platelet agglutination (by ristocetin), and thrombin generation on the endocardial surface.

Conclusions

CREB_A133 mice develop HF and endocardial endothelial dysfunction. Attenuation of the anti-coagulant APC pathway promotes endocardial thrombosis in early and acute decompensated phases of HF. However, in stable compensated HF mice, disruptions in endothelial vWF expression and extrusion may actually reduce the incidence of endocardial thrombosis.

The biology of neurotrophins: cardiovascular function

This chapter addresses the role of neurotrophins in the development of the heart, blood vessels, and neural circuits that control cardiovascular function, as well as the role of neurotrophins in the mature cardiovascular system. The cardiovascular system includes the heart and vasculature whose functions are tightly controlled by the nervous system. Neurons, cardiomyocytes, endothelial cells, vascular smooth muscle cells, and pericytes are all targets for neurotrophin action during development. Neurotrophin expression continues throughout life, and several common pathologies that impact cardiovascular function involve changes in the expression or activity of neurotrophins. These include atherosclerosis, hypertension, diabetes, acute myocardial infarction, and heart failure. In many of these conditions, altered expression of neurotrophins and/or neurotrophin receptors has direct effects on vascular endothelial and smooth muscle cells in addition to effects on nerves that modulate vascular resistance and cardiac function. This chapter summarizes the effects of neurotrophins in cardiovascular physiology and pathophysiology.

Sialoendoscopy in the management of salivary gland disorders--4 years experience

Sialoendoscopy is a minimally invasive technique used in the diagnosis and management of salivary gland disorders with promising success rates. Our objective is to describe our experience in sialoendoscopy, outlining our technique, success rates and complications, and to compare our data to those reported in the literature. A retrospective review and data analysis of all sialoendoscopic procedures performed by our service between 2006 and 2010 was performed. 41 patients were identified. 4 (9.7%) patients had normal findings, 2 (4.8%) had anatomical variants, 4 (9.7%) had benign strictures, 11 (26.8%) had mucinous debris and 20 (48%) had obstructing stones. Stone removal was successful in 19 (95%) of the 20 cases and symptomatic relief was achieved in 34 (83%) cases. In our experience a single interventional modality was used, despite that our success rates are similar to those reported in the literature where multiple therapeutic modalities were used.

Decreased adrenoceptor stimulation in heart failure rats reduces NGF expression by cardiac parasympathetic neurons

Postganglionic cardiac parasympathetic and sympathetic nerves are physically proximate in atrial cardiac tissue allowing reciprocal inhibition of neurotransmitter release, depending on demands from central cardiovascular centers or reflex pathways. Parasympathetic cardiac ganglion (CG) neurons synthesize and release the sympathetic neurotrophin nerve growth factor (NGF), which may serve to maintain these close connections. In this study we investigated whether NGF synthesis by CG neurons is altered in heart failure, and whether norepinephrine from sympathetic neurons promotes NGF synthesis. NGF and proNGF immunoreactivity in CG neurons in heart failure rats following chronic coronary artery ligation was investigated. NGF immunoreactivity was decreased significantly in heart failure rats compared to sham-operated animals, whereas proNGF expression was unchanged. Changes in neurochemistry of CG neurons included attenuated expression of the cholinergic marker vesicular acetylcholine transporter, and increased expression of the neuropeptide vasoactive intestinal polypeptide. To further investigate norepinephrine's role in promoting NGF synthesis, we cultured CG neurons treated with adrenergic receptor (AR) agonists. An 82% increase in NGF mRNA levels was detected after 1h of isoproterenol (β-AR agonist) treatment, which increased an additional 22% at 24h. Antagonist treatment blocked isoproterenol-induced increases in NGF transcripts. In contrast, the α-AR agonist phenylephrine did not alter NGF mRNA expression. These results are consistent with β-AR mediated maintenance of NGF synthesis in CG neurons. In heart failure, a decrease in NGF synthesis by CG neurons may potentially contribute to reduced connections with adjacent sympathetic nerves.

Sympathetic cardiac hyperinnervation and atrial autonomic imbalance in diet-induced obesity promote cardiac arrhythmias

Obesity increases the risk of arrhythmias and sudden cardiac death, but the mechanisms are unknown. This study tested the hypothesis that obesity-induced cardiac sympathetic outgrowth and hyperinnervation promotes the development of arrhythmic events. Male Sprague-Dawley rats (250-275 g), fed a high-fat diet (33% kcal/fat), diverged into obesity-resistant (OR) and obesity-prone (OP) groups and were compared with rats fed normal chow (13% kcal/fat; CON). In vitro experiments showed that both OR and OP rats exhibited hyperinnervation of the heart and high sympathetic outgrowth compared with CON rats, even though OR rats are not obese. Despite the hyperinnervation and outgrowth, we showed that, in vivo, OR rats were less susceptible to arrhythmic events after an intravenous epinephrine challenge compared with OP rats. On examining total and stimulus-evoked neurotransmitter levels in an ex vivo system, we demonstrate that atrial acetylcholine content and release were attenuated in OP compared with OR and CON groups. OP rats also expressed elevated atrial norepinephrine content, while norepinephrine release was suppressed. These findings suggest that the consumption of a high-fat diet, even in the absence of overt obesity, stimulates sympathetic outgrowth and hyperinnervation of the heart. However, normalized cardiac parasympathetic nervous system control may protect the heart from arrhythmic events.

Autonomic cardiac innervation: development and adult plasticity

Autonomic cardiac neurons have a common origin in the neural crest but undergo distinct developmental differentiation as they mature toward their adult phenotype. Progenitor cells respond to repulsive cues during migration, followed by differentiation cues from paracrine sources that promote neurochemistry and differentiation. When autonomic axons start to innervate cardiac tissue, neurotrophic factors from vascular tissue are essential for maintenance of neurons before they reach their targets, upon which target-derived trophic factors take over final maturation, synaptic strength and postnatal survival. Although target-derived neurotrophins have a central role to play in development, alternative sources of neurotrophins may also modulate innervation. Both developing and adult sympathetic neurons express proNGF, and adult parasympathetic cardiac ganglion neurons also synthesize and release NGF. The physiological function of these “non-classical” cardiac sources of neurotrophins remains to be determined, especially in relation to autocrine/paracrine sustenance during development.

 

Cardiac autonomic nerves are closely spatially associated in cardiac plexuses, ganglia and pacemaker regions and so are sensitive to release of neurotransmitter, neuropeptides and trophic factors from adjacent nerves. As such, in many cardiac pathologies, it is an imbalance within the two arms of the autonomic system that is critical for disease progression. Although this crosstalk between sympathetic and parasympathetic nerves has been well established for adult nerves, it is unclear whether a degree of paracrine regulation occurs across the autonomic limbs during development. Aberrant nerve remodeling is a common occurrence in many adult cardiovascular pathologies, and the mechanisms regulating outgrowth or denervation are disparate. However, autonomic neurons display considerable plasticity in this regard with neurotrophins and inflammatory cytokines having a central regulatory function, including in possible neurotransmitter changes. Certainly, neurotrophins and cytokines regulate transcriptional factors in adult autonomic neurons that have vital differentiation roles in development. Particularly for parasympathetic cardiac ganglion neurons, additional examinations of developmental regulatory mechanisms will potentially aid in understanding attenuated parasympathetic function in a number of conditions, including heart failure.

Altered atrial neurotransmitter release in transgenic p75(-/-) and gp130 KO mice

Heart rate is controlled by stimulatory sympathetic and inhibitory parasympathetic nerves innervating the sino-atrial node and cardiac conduction system. Sympathetic release of norepinephrine (NE) and parasympathetic release of acetylcholine (ACh) are controlled by the central nervous system, and by pre-synaptic inhibition of transmitter release within the atria. An increase in cardiac sympathetic transmission relative to parasympathetic transmission is pathological as it can lead to disturbances in heart rhythm, catecholaminergic toxicity and development of arrhythmias or fibrillation. Mice lacking the p75 neurotrophin receptor (p75(-/-)) have elevated atrial NE but a low heart rate suggesting autonomic dysregulation. Similarly, mice whose sympathetic neurons lack the gp130 cytokine receptor (gp130 KO) have a normal heart rate but enhanced bradycardia after vagal nerve stimulation. What is unclear is whether cardiac autonomic disturbances in these animals reflect systemic alterations in nerve activity or whether localized defects in neurotransmitter stores or release are involved. To examine local stimulus-evoked release of neurotransmitters, we have developed a novel method for simultaneous quantification of both NE and ACh after ex vivo atrial field stimulation. Using HPLC with electrochemical detection for NE, and HPLC with mass spectrometry for ACh, we found that following field stimulation NE release was impaired in p75(-/-) atria while ACh content and release was elevated in gp130 KO atria. Thus, alterations in localized transmitter release from atrial explants are consistent with in vivo deficits in heart rate control, suggesting peripheral alterations in autonomic transmission in these mice.

Inflammatory pseudotumours of the liver--role of dynamic MRI scan and surgical exploration

Inflammatory pseudotumours of the liver are extremely rare benign lesions. They were first described by Pack and Baker in 1953. They usually present with raised inflammatory markers and nonspecific abdominal symptoms. Most of these lesions are picked up incidentally on ultrasound scans. Diagnosis of these lesions poses a dilemma and a challenge due to their radiological similarities to other liver lesions such as hepatocellular carcinoma HCC. In this article we describe our experience in its diagnosis and management.

Cardiac ischemia-reperfusion regulates sympathetic neuropeptide expression through gp130-dependent and independent mechanisms

Cardiac function is regulated by a balance of sympathetic and parasympathetic transmission. Neuropeptide Y (NPY) and galanin (GAL) released from cardiac sympathetic neurons inhibits parasympathetic transmission in the heart. Sympathetic peptides may contribute to autonomic imbalance, which is characterized by increased sympathetic and decreased parasympathetic transmission and contributes to life threatening cardiovascular pathologies. Several gp130 cytokines are increased in the heart after myocardial infarction (MI), and these cytokines stimulate neuropeptide expression in sympathetic neurons. We used mice whose sympathetic neurons lack the gp130 receptor (gp130(DBH-Cre/lox) mice) to ask if cytokine activation of gp130 regulated neuropeptide expression in cardiac sympathetic nerves after MI. Myocardial infarction decreased NPY mRNA through a gp130 independent mechanism and increased VIP and PACAP mRNA via gp130, while GAL mRNA was unchanged. Immunohistochemistry revealed a gp130-dependent increase in PACAP38 in cells of the stellate ganglion after MI, and PACAP was detected in pre-ganglionic fibers of all genotypes and surgical groups. VIP was identified in a few sympathetic nerve fibers in all genotypes and surgical groups. GAL and PACAP38 were not detected in sham hearts, but peptide immunoreactivity was high in the infarct three days after MI. Surprisingly, peptides were abundant in cells that co-labeled with macrophage markers F4/80 and MAC2, but were not detected in sympathetic axons. PACAP protects cardiac myocytes from apoptosis, and GAL stimulates axon regeneration in addition to inhibiting parasympathetic transmission. Thus, these peptides may play an important role in cardiac and neuronal remodeling after ischemia-reperfusion.

Macrophage depletion suppresses sympathetic hyperinnervation following myocardial infarction

Myocardial infarction induces sympathetic axon sprouting adjacent to the necrotic region, and this has been implicated in the etiology of arrhythmias resulting in sudden cardiac death. Previous studies show that nerve growth factor (NGF) is essential for enhanced post-infarct sympathetic sprouting, but the cell types necessary to supply this neurotrophic protein are unknown. The objective of the present study was to determine whether macrophages, which are known to synthesize NGF, are necessary for post-infarct cardiac sympathetic sprouting. Ovariectomized female rats received left coronary artery ligation or sham operation, followed by intravenous injection of liposomes containing saline vehicle or clodronate, which kills macrophages. Sham-operated myocardium contained some sympathetic axons, few myofibroblasts and T cells and no CD-68-positive macrophages. In rats receiving saline liposomes through 7 days post-ligation, the posterolateral infarct border contained numerous myofibroblasts, macrophages and T cells, and sympathetic innervation was increased twofold. Treatment with clodronate liposomes reduced macrophage numbers by 69%, while myofibroblast area was reduced by 23% and T cell number was unaffected. Clodronate liposome treatment reduced sympathetic axon density to levels comparable to the uninfarcted heart. NGF protein content measured in western blots was reduced to 33% of that present in infarcts where rats received saline-containing liposomes. Tissue morphometry confirmed that NGF immunostaining was dramatically reduced, and this was attributable primarily to reduced macrophage content. These results show that macrophage destruction markedly reduces post-infarction levels of NGF and that the presence of elevated numbers of macrophages is obligatory for development of sympathetic hyperinnervation following myocardial infarction.

Modulation of rat parasympathetic cardiac ganglion phenotype and NGF synthesis by adrenergic nerves

Cardiac function is regulated by interactions among intrinsic and extrinsic autonomic neurons, and the mechanisms responsible for organizing these circuits are poorly understood. Parasympathetic neurons elsewhere synthesize the neurotrophin NGF, which may promote postganglionic axonal associations where parasympathetic axons inhibit sympathetic transmitter release. Previous studies have shown that parasympathetic NGF content and neurochemical phenotype are regulated by sympathetic innervation. In this study we assessed contributions of sympathetic input on cardiac ganglion neuronal phenotype and NGF expression. Because cardiac ganglia are reported to contain putative noradrenergic neurons, we eliminated sympathetic input both surgically (extrinsic) and chemically (extrinsic plus intrinsic). In controls, most cardiac ganglion neurons expressed vesicular acetylcholine transporter, frequently colocalized with vesicular monoamine transporter, but lacked catecholamine histofluorescence. Most cardiac ganglion neurons expressed NGF transcripts, and 40% contained mature and 47% proNGF immunoreactivity. Guanethidine treatment for 7 days decreased numbers of neurons expressing vesicular acetylcholine transporter, NGF transcripts and NGF immunoreactivity, but did not affect proNGF or vesicular monoamine transporter immunoreactivity. Stellate ganglionectomy had comparable effects on neurochemical phenotype and mature NGF immunoreactivity, but proNGF expression was additionally reduced. These findings show that individual cardiac ganglion neurons display markers of both cholinergic and noradrenergic transmission. Sympathetic noradrenergic innervation maintains levels of cholinergic but not noradrenergic marker protein. Sympathetic innervation also promotes cardiac ganglion neuronal NGF synthesis. Because chemical blockade of all noradrenergic transmission is no more effective than extrinsic sympathectomy, local intrinsic noradrenergic transmission is not a factor in regulating ganglion neuron phenotype.

Sympathetic hyperinnervation and inflammatory cell NGF synthesis following myocardial infarction in rats

Sympathetic hyperinnervation occurs in human ventricular tissue after myocardial infarction and may contribute to arrhythmias. Aberrant sympathetic sprouting is associated with elevated nerve growth factor (NGF) in many contexts, including ventricular hyperinnervation. However, it is unclear whether cardiomyocytes or other cell types are responsible for increased NGF synthesis. In this study, left coronary arteries were ligated and ventricular tissue examined in rats 1-28 days post-infarction. Infarct and peri-infarct tissue was essentially devoid of sensory and parasympathetic nerves at all time points. However, areas of increased sympathetic nerve density were observed in the peri-infarct zone between post-ligation days 4-14. Hyperinnervation occurred in regions containing accumulations of macrophages and myofibroblasts. To assess whether these inflammatory cells synthesize NGF, sections were processed for NGF in situ hybridization and immunohistochemistry. Both macrophage1 antigen-positive macrophages and alpha-smooth muscle actin-immunoreactive myofibroblasts expressed NGF in areas where they were closely proximate to sympathetic nerves. To investigate whether NGF produced by peri-infarct cells induces sympathetic outgrowth, we co-cultured adult sympathetic ganglia with peri-infarct explants. Neurite outgrowth from sympathetic ganglia was significantly greater at post-ligation days 7-14 as compared to control tissue. Addition of an NGF function-blocking antibody prevented the increased neurite outgrowth induced by peri-infarct tissue. These findings provide evidence that inflammatory cell NGF synthesis plays a causal role in sympathetic hyperinnervation following myocardial infarction.

Microneurography of human median nerve

PURPOSE

To examine the possibility of performing high-resolution MRI (microneurography) on peripheral nerves.

MATERIALS AND METHODS

A specific radio frequency (RF) coil was developed to probe the human median nerve at a magnetic field strength of 9.4 T and tested on three excised samples by acquiring microneurograms.

RESULTS

The microneurograms revealed neuronal tissue constituents at subfascicular level. The contrast features on proton-density and T1- and T2-weighted images were described and compared. The microscopic water movement was quantified using diffusion weighting parallel and orthogonal to the neuronal fiber orientation. The characteristics of anisotropic diffusion in the median nerve were comparable to those reported from other biological tissues (white matter and kidney).

CONCLUSION

The results overall suggest that microneurography might provide new noninvasive insights into microscopic gross anatomy of the peripheral nerve, injury evaluation, and efficacy of repair, although the feasibility at current clinically relevant field strengths is yet to be determined.

Estrogen alters trkA and p75 neurotrophin receptor expression within sympathetic neurons

Survival and growth of sympathetic neurons is regulated by nerve growth factor acting through trkA and p75NTR receptors. Sympathetic neurons are also affected by gonadal steroid hormones, particularly estrogen. To determine if estrogen may influence sympathetic neurons via altered neurotrophin receptor expression, we investigated effects of acute or chronic estrogen administration on levels of trkA and p75NTR proteins, numbers of immunoreactive neurons, and numbers of neurons expressing trkA, p75NTR, and estrogen receptor-alpha transcripts. Superior cervical ganglia from ovariectomized or estradiol-treated rats were processed for in situ hybridization or immunohistochemistry, and percentages of stained neurons quantitated or processed for Western blot analysis. In ovariectomized rats, approximately 50% of sympathetic neurons expressed trkA mRNA and protein. Acute estrogen administration did not affect trkA transcript expression, but reduced trkA protein significantly. Chronic treatment did not alter neuronal trkA expression. Approximately 70% of sympathetic neurons in ovariectomized rats expressed p75NTR transcripts and about 50% showed p75NTR immunoreactivity. Acute estrogen did not affect p75NTR expression. However, chronic estrogen reduced p75NTR mRNA and protein expression significantly. Fifty to sixty percent of sympathetic neurons in ovariectomized rats displayed estrogen receptor-alpha mRNA. After acute estrogen administration, estrogen receptor-alpha transcript expression increased by 35%, although this was not maintained chronically. These findings indicate that estrogen can influence sympathetic neuronal neurotrophin receptor expression as well as estrogen receptor-alpha. Reduced trkA expression after acute estrogen may transiently predispose neurons to degenerative events, while diminished p75NTR expression by chronic estrogen administration may exert long-term effects on survival or axonal outgrowth in sympathetic neurons.

Oestrogen regulates sympathetic neurite outgrowth by modulating brain derived neurotrophic factor synthesis and release by the rodent uterus

Sympathetic innervation of the adult rodent uterus undergoes cyclic remodelling. Terminal sympathetic axons degenerate when oestrogen levels rise and regenerate when oestrogen levels decline. This study examined the role of neurotrophins in oestrogen-mediated uterine sympathetic nerve remodelling. Oestrogen injection of ovariectomized female rats did not affect uterine NT-3 levels 24 h postinjection, and increased endometrial NGF protein, indicating that reduced NGF or NT-3 is not responsible for the oestrogen-induced denervation. Oestrogen also raised BDNF protein and mRNA in myometrium and endometrium. To assess whether increased BDNF affects uterine receptivity to sympathetic outgrowth, sympathetic ganglion explants were co-cultured with myometrium. Myometrium from ovariectomized rats induced neuritogenesis in oestrogen-free conditions, and this was abolished when BDNF was added to the medium. Neuritogenesis induced by ovariectomized myometrium was suppressed by oestrogen, and restored by a BDNF function-blocking antibody. To determine if target BDNF synthesis is required for oestrogen to suppress sympathetic neurite outgrowth, uteri from wild-type mice and mice homozygous or heterozygous for recombinant mutations of the BDNF gene were cultured with rat sympathetic ganglia. Neuritogenesis induced by wild-type uteri was diminished by oestrogen. Neurite formation in the presence of homozygous BDNF mutant uteri was not affected by oestrogen, but was lower than that of wild-type mice. Uteri from mice heterozygous for the BDNF mutation, who have reduced BDNF synthesis, showed normal neuritogenic properties, but were not affected by oestrogen. These findings suggest that oestrogen alters neuritogenic properties of the rodent uterus by regulating BDNF synthesis, which inhibits sympathetic neurite outgrowth.

Sympathetic neurons synthesize and secrete pro-nerve growth factor protein

Postmitotic sympathetic neuronal survival is dependent upon nerve growth factor (NGF) provided by peripheral targets, and this dependency serves as a central tenet of the neurotrophic hypothesis. In some other systems, NGF has been shown to play an autocrine role, although the pervasiveness and significance of this phenomenon within the nervous system remain unclear. We show here that rat sympathetic neurons synthesize and secrete NGF. NGF mRNA is expressed in nearly half of superior cervical ganglion sympathetic neurons at embryonic day 17, rising to over 90% in the early postnatal period, and declining in the adult. Neuronal immunoreactivity is reduced when retrograde transport is interrupted by axotomy, but persists in a subpopulation of neurons despite diminished mRNA expression, suggesting that intrinsic protein synthesis occurs. Cultured neonatal neurons express NGF mRNA, which is maintained even when they are undergoing apoptosis. To determine which NGF isoforms are secreted, we performed metabolic labeling and immunoprecipitation of NGF-immunoreactive proteins synthesized by cultured NGF-dependent and -independent neurons. Conditioned medium contained high molecular weight NGF precursor proteins, which varied depending upon the state of NGF dependence. Mature NGF was undetectable by these methods. High molecular weight NGF isoforms were also detected in ganglion homogenates, and persisted at diminished levels following axotomy. We conclude that sympathetic neurons express NGF mRNA, and synthesize and secrete pro-NGF protein. These findings suggest that a potential NGF-sympathetic neuron autocrine loop may exist in this prototypic target-dependent system, but that the secreted forms of this neurotrophin apparently do not support neuronal survival.

Modulation of parasympathetic neuron phenotype and function by sympathetic innervation

Selective sympathetic nerve dysfunction occurs during aging and in certain disease states. Here, we review findings concerning the effects of chronic sympathetic denervation on parasympathetic innervation to orbital target tissues in the adult rat. Long-term sympathetic denervation was induced by excising the ipsilateral superior cervical ganglion for 5-6 weeks prior to analyses. Following sympathectomy, pterygopalatine ganglion parasympathetic neurons show reduced nitric oxide synthase protein in their somata and projections to vascular targets. Laser Doppler measurements of ocular blood flow indicate that sympathectomy is also accompanied by reduced nitrergic vasodilatation. In the superior tarsal muscle of the eyelid, parasympathetic varicosities, normally, are distant to smooth muscle cells but make axo-axonal contacts with sympathetic nerves, consistent with physiological evidence showing only prejunctional inhibitory effects on sympathetically mediated smooth muscle contraction. Following sympathectomy, parasympathetic varicosities proliferate and closely appose smooth muscle cells, and this is accompanied by establishment of parasympathetic-smooth muscle excitatory neurotransmission. Many pterygopalatine parasympathetic neurons normally contain nerve growth factor (NGF) protein and express NGF mRNA. However, following chronic sympathectomy or elimination of sympathetic impulse activity, NGF mRNA and protein are markedly reduced, indicating that sympathetic neurotransmission enhances NGF expression in parasympathetic neurons. Together, these findings portray a striking dependency of parasympathetic neurons on sympathetic nerves to maintain normal phenotype and function. Sympathetic influences on parasympathetic neurons may be mediated, in part, through axo-axonal synapses. NGF synthesis and release by parasympathetic neurons may represent a molecular basis underlying the formation of these synapses, and up-regulation of NGF synthesis by sympathetic nerve activity may act to reinforce these associations.

The sweating apparatus in growth hormone deficiency, following treatment with r-hGH and in acromegaly

Adult growth hormone deficient patients are known to exhibit reduced sweating and their ability to thermoregulate is diminished. Treatment of these patients with recombinant human growth hormone (r-hGH) is claimed to reverse these abnormalities. We have investigated this claim, as well as the mechanism underlying these altered sweating responses in GH-deficient patients as part of a placebo-controlled study on the effects of 6-12 months r-hGH therapy. Skin biopsies were obtained from these subjects and changes in morphology and innervation parameters for the eccrine sweat glands were examined. These included histochemistry for acetylcholinesterase (AChE) and immunohistochemistry for the neuropeptide vasoactive intestinal polypeptide (VIP) and for PGP9.5, a general neuronal marker. Sweat gland acinar size and periacinar innervation were measured by computerised image analysis. The patients underwent pilocarpine iontophoresis sweat rate tests and their serum insulin-like growth factor 1 (IGF-1) levels were assessed. Since active acromegaly involves excess GH secretion and hyperhidrosis, skin biopsies and sweat tests were also carried out on a group of these patients, as well as on control subjects. We have demonstrated a sweating defect in adult GH-deficiency which is accompanied by a reduction in AChE and VIP levels in the nerve supply to sweat glands. Following r-hGH therapy, an increase in AChE and VIP staining is seen in the sudomotor nerves accompanied by restoration of sweat rates and serum IGF-1 levels. Hence, normalization of sweat gland function includes recovery of sudomotor synapse constituents. A trophic effect of GH on sweat gland epithelium and/or on the associated nerves is proposed, supported by the observation that in acromegaly the size of sweat gland acini and the density of innervation to the sweat glands was greater than in controls.

Nerve growth factor expression in parasympathetic neurons: regulation by sympathetic innervation

Interactions between sympathetic and parasympathetic nerves are important in regulating visceral target function. Sympathetic nerves are closely apposed to, and form functional synapses with, parasympathetic axons in many effector organs. The molecular mechanisms responsible for these structural and functional interactions are unknown. We explored the possibility that Nerve Growth Factor (NGF) synthesis by parasympathetic neurons provides a mechanism by which sympathetic-parasympathetic interactions are established. Parasympathetic pterygopalatine ganglia NGF-gene expression was examined by in situ hybridization and protein content assessed by immunohistochemistry. Under control conditions, NGF mRNA was present in approximately 60% and NGF protein was in 40% of pterygopalatine parasympathetic neurons. Peripheral parasympathetic axons identified by vesicular acetylcholine transporter-immunoreactivity also displayed NGF immunoreactivity. To determine if sympathetic innervation regulates parasympathetic NGF expression, the ipsilateral superior cervical ganglion was excised. Thirty days postsympathectomy, the numbers of NGF mRNA-positive neurons were decreased to 38% and NGF immunoreactive neurons to 15%. This reduction was due to a loss of sympathetic nerve impulse activity, as similar reductions were achieved when superior cervical ganglia were deprived of preganglionic afferent input for 40 days. These findings provide evidence that normally NGF is synthesized by parasympathetic neurons and transported anterogradely to fibre terminals, where it may be available to sympathetic axons. Parasympathetic NGF expression, in turn, is augmented by impulse activity within (and presumably transmitter release from) sympathetic axons. It is suggested that parasympathetic NGF synthesis and its modulation by sympathetic innervation provides a molecular basis for establishment and maintenance of autonomic axo-axonal synaptic interactions.

Coordinate expression of NGF and alpha-smooth muscle actin mRNA and protein in cutaneous wound tissue of developing and adult rats

Nerve growth factor (NGF) is synthesized in cutaneous wound tissue, and its higher levels in the neonate may contribute to more efficient wound healing. We used in situ hybridization and immunohistochemistry to define NGF mRNA and protein expression in intact skin and following excision wounding in neonatal and adult rats. To determine whether NGF is associated with wound contractile fibroblasts (myofibroblasts), we also examined expression of alpha-smooth muscle actin (alpha-SMA) mRNA and protein, established markers for these cells. In intact skin, NGF mRNA and protein were present in vascular and arrector pili smooth muscle, hair follicle sheath cells, keratinocytes, and hypodermal fibroblasts. Neonatal adipocytes and Schwann cells also expressed NGF mRNA and protein, while adult adipocytes and Schwann cells displayed only NGF-ir. Following wounding, NGF mRNA expression was exuberant in these cell types, and increased similarly at both ages and appeared de novo in skeletal muscle cells. Additionally, both NGF mRNA and protein were present in macrophages and myofibroblasts, and expression in myofibroblasts was significantly greater in neonates. Wound myofibroblasts also expressed alpha-SMA. Surprisingly, after wounding alpha-SMA mRNA and protein were present in essentially all cells in which NGF mRNA was detected. We conclude that NGF expression is enhanced in many cell types after wounding, but greater NGF synthesis in neonates appears to be due to a more robust myofibroblast response. In addition, cell types which demonstrated NGF mRNA also expressed alpha-SMA, and staining for both markers increased following wounding, suggesting synthesis of both proteins is regulated in a coordinated fashion.

Gonadotropin-releasing hormone immunoreactivity in the nasal epithelia of adults with Kallmann's syndrome and isolated hypogonadotropic hypogonadism and in the early midtrimester human fetus

GnRH-secreting neurons are known to originate in the epithelium of the medial olfactory placode, whence they migrate along the axons of the terminal nerve via the forebrain and into the hypothalamus. Synaptic contact between the developing olfactory bulbs and fascicles of the vomeronasal, terminal, and olfactory nerves does not occur in Kallmann's syndrome. Consequently, there is migration arrest of GnRH cells and partial or complete failure of formation of the olfactory bulbs, resulting in severe olfactory deficit and hypogonadotropic hypogonadism. In the present study, using an immunofluorescent, double immunostaining technique and confocal laser scanning microscopy, we observed GnRH-immunoreactive neurons in the hypothalamus of a 14-week-old human fetus. However, migration of GnRH neurons was not complete, and indeed, such cells were seen to be migrating along terminal nerve fascicles beneath the cribriform plate in a 16-week-old fetus. The same immunofluorescent technique demonstrated the presence of GnRH cells in biopsies of nasal mucosa obtained from three adults with Kallmann's syndrome, one normosmic subject with hypogonadotropic hypogonadism, and a eugonadal male cadaver. These findings are consistent with two different interpretations: the nasal GnRH neurons may be vestigial, representing cells that failed to migrate during embryogenesis; alternatively, they may have been generated de novo later in life, a possibility consistent with the recognized plasticity of human postnatal olfactory neuroepithelium. They also reveal that subjects with the normosmic (i.e. non-Kallmann's) form of GnRH deficiency are able to synthesize immunologically recognizable GnRH, implying that failure of GnRH synthesis is not responsible for this type of hypogonadotropic hypogonadism.

Serum and tissue sodium/potassium changes in estrogen treated female albino rats

Five control and ten estrogen treated albino rats were studied for changes in sodium and potassium in serum, heart, muscle, uterus and brain. The serum levels of sodium depleted significantly in the estrogen treated rats. Of the tissues studied, only uterus and brain had significantly sodium retention effect. The potassium levels on the other hand decreased significantly, both in serum and tissues following treatment with estrogen.

Continuous illumination and oogenesis in albino rabbits

Photo periodism is probably a phenomenon of natural selection. The critical period of ovulation can be adjusted to the environmental condition such as exposure to continuous illumination (LL) at constant temperature. Many investigators have also observed that blindness in girls causes early menarche while opposite results are obtained in rats. The present study was based upon the changes in circadian rhythm of ovaries of albino rabbits, by exposing the animals to continuous illumination through an electric bulb of 100 watt kept at one metre distance, at 37 degrees C, vaginal smear showed constant estrus. It was observed that degenerative changes started appearing in the histology of ovaries from first week of experiment. Degenerative changes were gradual and led to complete metaplasia or atrophy of ovary.