Monoclonal antibodies in neuro-ophthalmology

Neuro-ophthalmologic diseases include a broad range of disorders affecting the afferent and efferent visual pathways. Recently, monoclonal antibody (mAb) therapies have emerged as a promising targeted approach in the management of several of these complex conditions. Here, we describe the mechanism-specific applications and advancements in neuro-ophthalmologic mAb therapies. The application of mAbs in neuro-ophthalmologic diseases highlights our increasing understanding of disease-specific mechanisms in autoimmune conditions such as neuromyelitis optica, thyroid eye disease, and myasthenia gravis. Due to the specificity of mAb therapies, applications in neuro-ophthalmologic diseases have yielded exceptional clinical outcomes, including both reduced rate of relapse and progression to disability, visual function preservation, and quality of life improvement. These advancements have not only expanded the range of treatable neuro-ophthalmologic diseases but also reduced adverse events and increased the response rate to treatment. Further research into neuro-ophthalmologic disease mechanisms will provide accurate and specific targeting of important disease mediators through applications of future mAbs. As our understanding of these diseases and the relevant therapeutic targets evolve, we will continue to build on our understanding of how mAbs interfere with disease pathogenesis, and how these changes improve clinical outcomes and quality of life for patients.

Predictors of postoperative performance status after surgical management of infratemporal fossa malignancies

Infratemporal fossa (ITF) tumors are difficult to access surgically due to anatomical constraints. Moreover, aggressive ITF carcinomas and sarcomas necessitate aggressive treatment strategies that, along with tumor-related symptoms, contribute to decreases in patient performance status. To assess factors that predict postoperative performance in patients undergoing surgery for ITF tumors. We reviewed medical records for all patients surgically treated for an ITF malignancy between January 1, 1999, and December 31, 2017, at our institution. We collected patient demographics, preoperative performance, tumor stage, tumor characteristics, treatment modalities, pathological data, and postoperative performance data. The 5-year survival rate was 62.2%. Higher preoperative Karnofsky Performance Status (KPS) score (n = 64; p < 0.001), short length of stay (p = 0.002), prior surgery at site (n = 61; p = 0.0164), and diagnosis of sarcoma (n = 62; p = 0.0398) were predictors of higher postoperative KPS scores. Percutaneous endoscopic gastrostomy (PEG) (n = 9; p = 0.0327), and tracheostomy tube placement (n = 20; p = 0.0436) were predictors of lower postoperative KPS scores, whereas age at presentation (p = 0.72), intracranial tumor spread (p = 0.8197), and perineural invasion (n = 40; p = 0.2195) were not. Male patients and patients with carcinomas showed the greatest decreases in KPS scores between pretreatment and posttreatment. Higher preoperative KPS score and short length of stay were the best predictors of higher postoperative KPS scores. This work provides treatment teams and patients with better information on outcomes for shared decision-making.

Lymphocytic Panhypophysitis Mimicking Glaucoma: Case Report

Lymphocytic hypophysitis (LH) is a primary inflammatory disorder of the pituitary gland and infundibulum that commonly manifests in both mass effect and endocrinologic symptoms. Although the exact pathophysiology remains unclear, it has been increasingly linked to an autoimmune process. Complications arise by two separate mechanisms. Inflammation in the sella can lead to headaches and visual field defects. Pituitary inflammation and, chronically, fibrosis interfere with the gland's hormone-secreting capacity, often resulting in various endocrinopathies such as polyuria, polydipsia, amenorrhea, and others. While final histologic classification requires pathologic evaluation, diagnosis can often be made clinically with appropriate imaging. Treatment often consists of conservative management but can also include glucocorticoids or surgical resection. We present a case of biopsy-proven LH involving the entire pituitary, dubbed lymphocytic panhypophysitis (LPH) that was misdiagnosed for years as glaucoma due to the lack of endocrinopathy as well as delay in magnetic resonance imaging. After imaging revealed the sellar mass, the patient responded symptomatically to surgical resection and glucocorticoid treatment. LPH may present without endocrinologic symptoms and therefore mimic alternate diagnoses such as glaucoma. Clinicians should be suspicious of a diagnosis of glaucoma in the setting of a temporal field defect and lack of response to traditional therapy. A personal or family history of autoimmune disease in such patients should prompt further imaging and investigation. Therefore, endocrinopathy is supportive but not present in every case of LPH.

Oxytocin signaling is necessary for synaptic maturation of adult-born neurons

Neural circuit plasticity and sensory response dynamics depend on forming new synaptic connections. Despite recent advances toward understanding the consequences of circuit plasticity, the mechanisms driving circuit plasticity are unknown. Adult-born neurons within the olfactory bulb have proven to be a powerful model for studying circuit plasticity, providing a broad and accessible avenue into neuron development, migration, and circuit integration. We and others have shown that efficient adult-born neuron circuit integration hinges on presynaptic activity in the form of diverse signaling peptides. Here, we demonstrate a novel oxytocin-dependent mechanism of adult-born neuron synaptic maturation and circuit integration. We reveal spatial and temporal enrichment of oxytocin receptor expression within adult-born neurons in the murine olfactory bulb, with oxytocin receptor expression peaking during activity-dependent integration. Using viral labeling, confocal microscopy, and cell type-specific RNA-seq, we demonstrate that oxytocin receptor signaling promotes synaptic maturation of newly integrating adult-born neurons by regulating their morphological development and expression of mature synaptic AMPARs and other structural proteins.

Distinct immune signature predicts progression of vestibular schwannoma and unveils a possible viral etiology

BACKGROUND

The management of sub-totally resected sporadic vestibular schwannoma (VS) may include observation, re-resection or irradiation. Identifying the optimal choice can be difficult due to the disease's variable progression rate. We aimed to define an immune signature and associated transcriptomic fingerprint characteristic of rapidly-progressing VS to elucidate the underpinnings of rapidly progressing VS and identify a prognostic model for determining rate of progression.

METHODS

We used multiplex immunofluorescence to characterize the immune microenvironment in 17 patients with sporadic VS treated with subtotal surgical resection alone. Transcriptomic analysis revealed differentially-expressed genes and dysregulated pathways when comparing rapidly-progressing VS to slowly or non-progressing VS.

RESULTS

Rapidly progressing VS was distinctly enriched in CD4⁺, CD8⁺, CD20⁺, and CD68⁺ immune cells. RNA data indicated the upregulation of anti-viral innate immune response and T-cell senescence. K - Top Scoring Pair analysis identified 6 pairs of immunosenescence-related genes (CD38-KDR, CD22-STAT5A, APCS-CXCR6, MADCAM1-MPL, IL6-NFATC3, and CXCL2-TLR6) that had high sensitivity (100%) and specificity (78%) for identifying rapid VS progression.

CONCLUSION

Rapid progression of residual vestibular schwannoma following subtotal surgical resection has an underlying immune etiology that may be virally originating; and despite an abundant adaptive immune response, T-cell immunosenescence may be associated with rapid progression of VS. These findings provide a rationale for clinical trials evaluating immunotherapy in patients with rapidly progressing VS.

Co-transmitting neurons in the lateral septal nucleus exhibit features of neurotransmitter switching

The lateral septal nucleus (LSN) is a highly interconnected region of the central brain whose activity regulates widespread circuitry. As such, the mechanisms that govern neuronal activity within the LSN have far-reaching implications on numerous brain-wide nuclei, circuits, and behaviors. We found that GABAergic neurons within the LSN express markers that mediate the release of acetylcholine (ACh). Moreover, we show that these vGATLSN neurons release both GABA and ACh onto local glutamatergic LSN neurons. Using both short-term and long-term neuronal labeling techniques we observed expression of the cholinergic neuron marker Choline Acetyltransferase (ChAT) in vGATLSN neurons. These findings provide evidence of cholinergic neurotransmission from vGATLSN neurons, and provide an impetus to examine dynamic co-neurotransmission changes as a potential mechanism that contributes to neuronal and circuit-wide plasticity within the LSN.

Advancements in the Quest to Map, Monitor, and Manipulate Neural Circuitry

Neural circuits and the cells that comprise them represent the functional units of the brain. Circuits relay and process sensory information, maintain homeostasis, drive behaviors, and facilitate cognitive functions such as learning and memory. Creating a functionally-precise map of the mammalian brain requires anatomically tracing neural circuits, monitoring their activity patterns, and manipulating their activity to infer function. Advancements in cell-type-specific genetic tools allow interrogation of neural circuits with increased precision. This review provides a broad overview of recombination-based and activity-driven genetic targeting approaches, contemporary viral tracing strategies, electrophysiological recording methods, newly developed calcium, and voltage indicators, and neurotransmitter/neuropeptide biosensors currently being used to investigate circuit architecture and function. Finally, it discusses methods for acute or chronic manipulation of neural activity, including genetically-targeted cellular ablation, optogenetics, chemogenetics, and over-expression of ion channels. With this ever-evolving genetic toolbox, scientists are continuing to probe neural circuits with increasing resolution, elucidating the structure and function of the incredibly complex mammalian brain.

A CRISPR toolbox for generating intersectional genetic mouse models for functional, molecular, and anatomical circuit mapping

BACKGROUND

The functional understanding of genetic interaction networks and cellular mechanisms governing health and disease requires the dissection, and multifaceted study, of discrete cell subtypes in developing and adult animal models. Recombinase-driven expression of transgenic effector alleles represents a significant and powerful approach to delineate cell populations for functional, molecular, and anatomical studies. In addition to single recombinase systems, the expression of two recombinases in distinct, but partially overlapping, populations allows for more defined target expression. Although the application of this method is becoming increasingly popular, its experimental implementation has been broadly restricted to manipulations of a limited set of common alleles that are often commercially produced at great expense, with costs and technical challenges associated with production of intersectional mouse lines hindering customized approaches to many researchers. Here, we present a simplified CRISPR toolkit for rapid, inexpensive, and facile intersectional allele production.

RESULTS

Briefly, we produced 7 intersectional mouse lines using a dual recombinase system, one mouse line with a single recombinase system, and three embryonic stem (ES) cell lines that are designed to study the way functional, molecular, and anatomical features relate to each other in building circuits that underlie physiology and behavior. As a proof-of-principle, we applied three of these lines to different neuronal populations for anatomical mapping and functional in vivo investigation of respiratory control. We also generated a mouse line with a single recombinase-responsive allele that controls the expression of the calcium sensor Twitch-2B. This mouse line was applied globally to study the effects of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) on calcium release in the ovarian follicle.

CONCLUSIONS

The lines presented here are representative examples of outcomes possible with the successful application of our genetic toolkit for the facile development of diverse, modifiable animal models. This toolkit will allow labs to create single or dual recombinase effector lines easily for any cell population or subpopulation of interest when paired with the appropriate Cre and FLP recombinase mouse lines or viral vectors. We have made our tools and derivative intersectional mouse and ES cell lines openly available for non-commercial use through publicly curated repositories for plasmid DNA, ES cells, and transgenic mouse lines.

A systematic-review of olfactory deficits in neurodevelopmental disorders: From mouse to human

Olfactory impairment is a common clinical motif across neurodevelopmental disorders, suggesting olfactory circuits are particularly vulnerable to disease processes and can provide insight into underlying disease mechanisms. The mouse olfactory bulb is an ideal model system to study mechanisms of neurodevelopmental disease due to its anatomical accessibility, behavioral relevance, ease of measuring circuit input and output, and the feature of adult neurogenesis. Despite the clinical relevance and experimental benefits, olfactory testing across animal models of neurodevelopmental disease has been inconsistent and non-standardized. Here we performed a systematic literature review of olfactory function testing in mouse models of neurodevelopmental disorders, and identified intriguing inconsistencies that include evidence for both increased and decreased acuity in odor detection in various mouse models of Autism Spectrum Disorder (ASD). Based on our identified gaps in the literature, we recommend direct comparison of different mouse models of ASD using standardized tests for odor detection and discrimination. This review provides a framework to guide future olfactory function testing in mouse models of neurodevelopmental diseases.

Imaging and Quantification of Intact Neuronal Dendrites via CLARITY Tissue Clearing

Brain activity, the electrochemical signals passed between neurons, is determined by the connectivity patterns of neuronal networks, and from the morphology of processes and substructures within these neurons. As such, much of what is known about brain function has arisen alongside developments in imaging technologies that allow further insight into how neurons are organized and connected in the brain. Improvements in tissue clearing have allowed for high-resolution imaging of thick brain slices, facilitating morphological reconstruction and analyses of neuronal substructures, such as dendritic arbors and spines. In tandem, advances in image processing software provide methods of quickly analyzing large imaging datasets. This work presents a relatively rapid method of processing, visualizing, and analyzing thick slices of labeled neural tissue at high-resolution using CLARITY tissue clearing, confocal microscopy, and image analysis. This protocol will facilitate efforts toward understanding the connectivity patterns and neuronal morphologies that characterize healthy brains, and the changes in these characteristics that arise in diseased brain states.

Mini-review: Trophic interactions between cancer cells and primary afferent neurons

Cancer neurobiology is an emerging discipline that inevitably unfurls new perspectives in oncology. The role that nerves play in cancer progression resonates with the long-reported dependency of tumors on neuro-molecular mechanisms that remain insufficiently elucidated. Whereas interactions between neurotrophic growth factors and receptors have been heavily studied in the nervous system, their expression in cancers and their impact on tumor cell growth and metastasis through their corresponding signaling pathways has been undervalued. Accumulating evidence suggests that trophic factors released by nerves strongly influence tumor development and that this neural contribution appears to not only play a stimulatory role but also function as an essential part of the tumor's microenvironment. This bidirectional communication between proliferating cells and tumor-infiltrating nerves drives axonogenesis and tumor growth and migration. Acquiring a better understanding of the trophic interactions between primary afferent neurons and invading tumors will guide clinically actionable strategies to prevent tumor-associated axonogenesis, disrupting the chemical crosstalk between neurons and tumors and ultimately decreasing tumor growth and spread.

Head and neck cancer exosomes drive microRNA-mediated reprogramming of local neurons

Solid tumors are complex collections of cells surrounded by benign tissues that influence and are influenced by the tumor. These surrounding cells include vasculature, immune cells, neurons, and other cell types, and are collectively known as the tumor microenvironment. Tumors manipulate their microenvironment for the benefit of the tumor. Autonomic neurons innervate and drive malignant growth in a variety of solid tumors. However, the mechanisms underlying neuron-tumor relationships are not well understood. Recently, Amit et al. described that trophic relationships between oral cavity squamous cell carcinomas (OCSCCs) and nearby autonomic neurons arise through direct signaling between tumors and local neurons. An inducible tumor model in which 4NQO was introduced into the drinking water of Trp53 knockout mice was used to model OCSCC-microenvironment interactions. Using this model, this group discovered that loss of p53 expression in OCSCC tumors resulted in increased nerve density within these tumors. This neuritogenesis was controlled by tumor-derived microRNA-laden extracellular vesicles (EVs). Specifically, EV-delivered miR-34a inhibited neuritogenesis, whereas EV-delivered miR-21 and miR-324 increased neuritogenesis. The neurons innervating p53-deficient OCSCC tumors were predominantly adrenergic and arose through the transdifferentiation of trigeminal sensory nerve fibers to adrenergic nerve fibers. This transdifferentiation corresponded with increased expression of neuron-reprogramming transcription factors, including POU5F1, KLF4, and ASCL1, which were overexpressed in the p53-deficient samples, and are proposed targets of miR-34a-mediated regulation. Human OCSCC samples enriched in adrenergic neuron markers are associated strongly with poor outcomes, thus demonstrating the relevance of these findings to cancer patients.

Interrupting Neuron-Tumor Interactions to Overcome Treatment Resistance

Neurons in the tumor microenvironment release neurotransmitters, neuroligins, chemokines, soluble growth factors, and membrane-bound growth factors that solid tumors leverage to drive their own survival and spread. Tumors express nerve-specific growth factors and microRNAs that support local neurons and guide neuronal growth into tumors. The development of feed-forward relationships between tumors and neurons allows tumors to use the perineural space as a sanctuary from therapy. Tumor denervation slows tumor growth in animal models, demonstrating the innervation dependence of growing tumors. Further in vitro and in vivo experiments have identified many of the secreted signaling molecules (e.g., acetylcholine, nerve growth factor) that are passed between neurons and cancer cells, as well as the major signaling pathways (e.g., MAPK/EGFR) involved in these trophic interactions. The molecules involved in these signaling pathways serve as potential biomarkers of disease. Additionally, new treatment strategies focus on using small molecules, receptor agonists, nerve-specific toxins, and surgical interventions to target tumors, neurons, and immune cells of the tumor microenvironment, thereby severing the interactions between tumors and surrounding neurons. This article discusses the mechanisms underlying the trophic relationships formed between neurons and tumors and explores the emerging therapies stemming from this work.

Surgical management of carcinomas of the infratemporal fossa and skull base: patterns of failure and predictors of long-term outcomes

OBJECTIVE

Infratemporal fossa (ITF) tumors are unique in histological characteristics and difficult to treat. Predictors of patient outcomes in this context are not known. The objective of this study was to identify independent predictors of outcome and to characterize patterns of failure in patients with ITF carcinoma.

METHODS

All patients who had been surgically treated for anterolateral skull base malignancy between 1999 and 2017 at the authors' institution were retrospectively reviewed. Patient demographics, preoperative performance status, tumor stage, tumor characteristics, treatment modalities, and pathological data were collected. Primary outcomes were disease-specific survival (DSS) and local progression-free survival (LPFS) rates. Overall survival (OS) and patterns of progression were secondary outcomes.

RESULTS

Forty ITF malignancies with skull base involvement were classified as carcinoma. Negative margins were achieved in 23 patients (58%). Median DSS and LPFS were 32 and 12 months, respectively. Five-year DSS and OS rates were 55% and 36%, respectively. The 5-year LPFS rate was 69%. The 5-year overall PFS rate was 53%. Disease recurrence was noted in 28% of patients. Age, preoperative performance status, and margin status were statistically significant prognostic factors for DSS. Lower preoperative performance status and positive surgical margins increased the probability of local recurrence.

CONCLUSIONS

The ability to achieve negative margins was significantly associated with improved tumor control rates and DSS. Cranial base surgical approaches must be considered in multimodal treatment regimens for anterolateral skull base carcinomas.

Oxytocin and Sensory Network Plasticity

An essential characteristic of nervous systems is their capacity to reshape functional connectivity in response to physiological and environmental cues. Endogenous signals, including neuropeptides, governs nervous system plasticity. Particularly, oxytocin has been recognized for its role in mediating activity-dependent circuit changes. These oxytocin-dependent changes occur at the synaptic level and consequently shape the cellular composition of circuits. Here we discuss recent advances that illustrate how oxytocin functions to reshape neural circuitry in response to environmental changes. Excitingly, recent findings pave the way for promising therapeutic applications of oxytocin to treat neurodevelopmental and neuropsychiatric diseases.

Improving long term patient outcomes from deep brain stimulation for treatment-refractory obsessive-compulsive disorder

Introduction: Deep brain stimulation (DBS) has emerged as an effective treatment for patients with severe treatment-refractory obsessive-compulsive disorder (OCD). Over the past two decades, several clinical trials with multiple years of follow-up have shown that DBS offers long-term symptom relief for individuals with severe OCD, though a portion of patients do not achieve an adequate response.Areas covered: This review sought to summarize the literature on the efficacy and long-term effectiveness of DBS for OCD, and to identify strategies that have the potential to improve treatment outcomes.Expert opinion: Although this literature is just emerging, a small number of DBS enhancement strategies have shown promising initial results. More posterior targets along the striatal axis and at the bed nucleus of the stria terminalis appear to offer greater symptom relief than more anterior targets. Research is also beginning to demonstrate the feasibility of maximizing treatment outcomes with target selection based on neural activation patterns during symptom provocation and clinical presentation. Finally, integrating DBS with post-surgery exposure and response prevention therapy appears to be another promising approach. Definitive conclusions about these strategies are limited by a low number of studies with small sample sizes that will require multi-site replication.

Single-Cell RNA-Seq of Mouse Olfactory Bulb Reveals Cellular Heterogeneity and Activity-Dependent Molecular Census of Adult-Born Neurons

Cellular heterogeneity within the mammalian brain poses a challenge toward understanding its complex functions. Within the olfactory bulb, odor information is processed by subtypes of inhibitory interneurons whose heterogeneity and functionality are influenced by ongoing adult neurogenesis. To investigate this cellular heterogeneity and better understand adult-born neuron development, we utilized single-cell RNA sequencing and computational modeling to reveal diverse and transcriptionally distinct neuronal and nonneuronal cell types. We also analyzed molecular changes during adult-born interneuron maturation and uncovered developmental programs within their gene expression profiles. Finally, we identified that distinct neuronal subtypes are differentially affected by sensory experience. Together, these data provide a transcriptome-based foundation for investigating subtype-specific neuronal function in the olfactory bulb (OB), charting the molecular profiles that arise during the maturation and integration of adult-born neurons and how they dynamically change in an activity-dependent manner.

Using single-cell sequencing, Tepe et al. describe cellular heterogeneity in the mouse olfactory bulb, uncover markers for each cell type, and reveal differentially regulated genes in adult-born neurons. These findings provide a framework for studying cell-type-specific functions and circuit integration in the mammalian brain.

Surgical Resection of an Optic Nerve Sheath Meningioma: Relevance of Endoscopic Endonasal Approaches to the Optic Canal

Optic nerve sheath meningiomas (ONSMs) account for less than 2% of meningiomas and 1.7% of orbital tumors. Although rare, the management of these tumors is important as unilateral blindness often results in untreated cases. Radiotherapy has emerged as the preferred treatment. However, therapies for ONSMs are controversial due to the variable natural history of the disease and limitations of surgical and radiotherapy options. A 60-year-old woman presented with monocular left diminished color perception and blurred vision. Magnetic resonance imaging demonstrated a homogenously enhancing 5-mm left optic nerve mass with evidence of nerve compression. Conservative management was advised. However, 1 month after diagnosis her visual acuity deteriorated further. Because of the small focal location of the tumor within the optic canal, surgery was considered. Given the tumor's location inferomedial to the optic nerve, an endoscopic endonasal approach to the optic canal was performed. This patient recovered fully with resolution of visual symptoms immediately following surgery. Postoperative imaging 24 hours after surgery demonstrated gross total resection of the tumor; 1 year postoperatively the patient has a normal ophthalmologic examination. This report highlights the value of endoscopic endonasal approaches in the management of select optic canal pathology, otherwise inaccessible via transcranial approaches.

Evolution of a genetic incompatibility in the genus Xiphophorus

Genetic incompatibilities are commonly observed between hybridizing species. Although this type of isolating mechanism has received considerable attention, we have few examples describing how genetic incompatibilities evolve. We investigated the evolution of two loci involved in a classic example of a Bateson-Dobzhansky-Muller (BDM) incompatibility in Xiphophorus, a genus of freshwater fishes from northern Central America. Hybrids develop a lethal melanoma due to the interaction of two loci, an oncogene and its repressor. We cloned and sequenced the putative repressor locus in 25 Xiphophorus species and an outgroup species, and determined the status of the oncogene in those species from the literature. Using phylogenetic analyses, we find evidence that a repeat region in the proximal promoter of the repressor is coevolving with the oncogene. The data support a hypothesis that departs from the standard BDM model: it appears the alleles that cause the incompatibilities have coevolved simultaneously within lineages, rather than in allopatric or temporal isolation.

Recommended evaluation of adrenal incidentalomas is costly, has high false-positive rates and confers a risk of fatal cancer that is similar to the risk of the adrenal lesion becoming malignant; time for a rethink?

OBJECTIVE

To assess the performance of current clinical recommendations for the evaluation of an adrenal incidentaloma. DESIGN AND METHODS LITERATURE REVIEW: Electronic databases (Pubmed, Ovid and citation searches from key articles) from 1980 to 2008 were searched. Eligible studies were those deemed most applicable to the clinical scenario of a patient referred to an endocrinologist for assessment of an incidentally detected adrenal mass. Surgical series, histopathological series and oncological series were reviewed and most were excluded.

RESULTS

The prevalence of functional and malignant lesions presenting as adrenal incidentaloma was similar to that quoted in most reviews, other than a lower incidence of adrenal carcinoma (1.9 vs 4.7%) and metastases (0.7 vs 2.3%). The development of functionality or malignancy during follow-up was rare (<1% becoming functional and 0.2% becoming malignant). During follow-up, false-positive rates of the recommended investigations are typically 50 times greater than true positive rates. The average recommended computed tomography (CT) scan follow-up exposes each patient to 23 mSv of ionising radiation, equating to a 1 in 430 to 2170 chance of causing fatal cancer. This is similar to the chance of developing adrenal malignancy during 3-year follow-up of adrenal incidentaloma.

CONCLUSION

Current recommendations for evaluation of adrenal incidentaloma are likely to result in significant costs, both financial and emotional, due to high false-positive rates. The dose of radiation involved in currently recommended CT scan follow-up confers a risk of fatal cancer that is similar to the risk of the adrenal becoming malignant. This argues for a review of current guidelines.

A genome-wide screen in 1119 relative pairs with autoimmune thyroid disease

CONTEXT

Autoimmune thyroid diseases (AITD), comprising Graves' disease and autoimmune hypothyroidism, are characterized by loss of immunological self-tolerance to thyroid antigens. These are complex diseases arising from a combination of genetic and environmental factors. An understanding of the genetic susceptibility factors for AITD could help to target treatments more effectively and identify people at risk for these conditions.

OBJECTIVE

The objective of this study was to identify regions of genetic linkage to AITD that could potentially harbor genetic susceptibility factors for these conditions.

DESIGN

The study design was a genome-wide screen performed on affected relative pairs with AITD.

SETTING

Patients were recruited through hospital endocrinology clinics.

PARTICIPANTS

Some 1119 Caucasian relative pairs affected with AITD (Graves' disease or autoimmune hypothyroidism) were recruited into the study.

INTERVENTION

Blood samples were obtained from each participant for DNA analysis, and clinical questionnaires were completed.

MAIN OUTCOME MEASURE

The study aimed to identify regions of genetic linkage to AITD.

RESULTS

Three regions of suggestive linkage were obtained on chromosomes 18p11 (maximum LOD score, 2.5), 2q36 (maximum LOD score, 2.2), and 11p15 (maximum LOD score, 2.0). No linkage to human leukocyte antigen was found.

CONCLUSIONS

The absence of significant evidence of linkage at any one locus in such a large dataset argues that genetic susceptibility to AITD reflects a number of loci, each with a modest effect. Linkage analysis may be limited in defining such loci, and large-scale association studies may prove to be more useful in identifying genetic susceptibility factors for AITD.

The DNA sequence and analysis of human chromosome 13

Chromosome 13 is the largest acrocentric human chromosome. It carries genes involved in cancer including the breast cancer type 2 (BRCA2) and retinoblastoma (RB1) genes, is frequently rearranged in B-cell chronic lymphocytic leukaemia, and contains the DAOA locus associated with bipolar disorder and schizophrenia. We describe completion and analysis of 95.5 megabases (Mb) of sequence from chromosome 13, which contains 633 genes and 296 pseudogenes. We estimate that more than 95.4% of the protein-coding genes of this chromosome have been identified, on the basis of comparison with other vertebrate genome sequences. Additionally, 105 putative non-coding RNA genes were found. Chromosome 13 has one of the lowest gene densities (6.5 genes per Mb) among human chromosomes, and contains a central region of 38 Mb where the gene density drops to only 3.1 genes per Mb.

Predicting surgically remedial primary aldosteronism: role of adrenal scanning, posture testing, and adrenal vein sampling

Distinguishing surgically remedial forms from other causes of primary aldosteronism (PA) may be difficult, and it is made more challenging by the earlier detection of milder disease. The technical demands of bilateral adrenal vein sampling (AVS)-increasingly advocated for localizing a unilateral autonomous lesion (UAL)- and lack of agreed criteria for establishing unilateral autonomy, add further to the diagnostic challenge. This retrospective review of 49 hypokalemic patients with unequivocal PA (41 with surgically proven and remedial UAL, eight patients with bilateral adrenal hyperplasia) analyzes the value of computerized tomography adrenal scanning (n = 32), 4 h erect posture testing (n = 42), and AVS (n = 27) in predicting and lateralizing a surgically remedial lesion. A fall in plasma aldosterone during 4 h erect posture (positive test) occurred in 63% of patients with UAL and in none with bilateral adrenal hyperplasia. A positive posture test or computerized tomography adrenal scan (single focal macroadenoma) both had high positive predictive value (100% and 89% respectively), but low sensitivity for diagnosis of UAL. AVS, undertaken during low dose ACTH stimulation, localized the UAL in all cases (positive predictive value 100%) where the aldosterone/cortisol ratio of blood drawn from the uninvolved gland was less than that of peripheral blood (contralateral ratio <1). Biochemical severity, reflected by overnight supine plasma aldosterone, was strongly correlated with the degree of contralateral gland suppression (n = 16, r = 0.79, P < 0.001). Importantly, the AVS findings show that when bilateral access is not possible, UAL can be successfully lateralized when only one adrenal vein (the contralateral) is accessed, or the ipsilateral vein is sampled in subjects whose posture test was positive. In this series of patients with overt (hypokalemic) PA, preoperative testing successfully identified a surgically remedial lesion in 39 of 41 cases. Confirmation of the recommended diagnostic approach must now await larger prospective studies.

Histocompatibility leucocyte antigens and closely linked immunomodulatory genes in autoimmune thyroid disease

OBJECTIVES

Associations between autoimmune thyroid disease and antigens of the major histocompatibility complex (MHC) have long been recognized. Graves' disease (GD) is associated with the histocompatibility leucocyte antigen (HLA) haplotype A*01-B*0801-DRB1*0301-DQA1*0501-DQB1*0201 (or B8/DR3) whereas autoimmune hypothyroidism (AIH) has been weakly associated with HLA DRB1*03, *04 and *11/*12 alleles (or DR3, DR4 and DR5). However, the presence of important immunoregulatory genes within the HLA Class II and III regions raises the possibility that these genes harbour the primary susceptibility locus. This study examines genetic variation across the MHC in UK Caucasoid subjects with autoimmune thyroid disease.

PATIENTS AND METHODS

DNA extracted from venous blood samples from 215 patients with autoimmune thyroid disease (GD 135, AIH 77) and 267 control subjects was analysed. Genotyping was performed using polymerase chain reaction and sequence specific primers for HLA Class I and II alleles and polymorphisms within the TAP1, TAP2, tumour necrosis factor (TNF), lymphotoxin alpha (LTalpha), heat shock protein (HSP)70-1, HSP70-2 and HSP70-Hom genes.

RESULTS

For GD, the strongest association was with DRB1*03 [56% patients positive vs. 24% controls, P = 2 x 10(-10), odds ratio (OR) 4.0]. Positive associations were also seen for DRB1*03 linked alleles, B*0801, DRB3*01/02, DQA1*05, DQB1*02 and DPB1*0101 (OR 2.3-3.4). Specific TNF and LTalpha alleles were strongly associated with GD (Pc = 3 x 10(-5) and 0.001) and weak associations were seen for HSP70-1 + 190C and HSP70-2 + 1267G polymorphisms (Pc = 0.05 and 0.01). These associations were not significant when DRB1*03 status was considered. Patients with AIH showed only a weak association with DQB1*03 (P = 0.02).

CONCLUSIONS

These results show that, of the polymorphisms tested within the MHC, GD is most strongly associated with DRB1*03, and associations with other immunoregulatory genes previously described in Caucasian subjects most likely reflect linkage disequilibrium. AIH differs from GD, being less influenced by the MHC region.

The physical maps for sequencing human chromosomes 1, 6, 9, 10, 13, 20 and X

We constructed maps for eight chromosomes (1, 6, 9, 10, 13, 20, X and (previously) 22), representing one-third of the genome, by building landmark maps, isolating bacterial clones and assembling contigs. By this approach, we could establish the long-range organization of the maps early in the project, and all contig extension, gap closure and problem-solving was simplified by containment within local regions. The maps currently represent more than 94% of the euchromatic (gene-containing) regions of these chromosomes in 176 contigs, and contain 96% of the chromosome-specific markers in the human gene map. By measuring the remaining gaps, we can assess chromosome length and coverage in sequenced clones.

Improvement in mood and fatigue after dehydroepiandrosterone replacement in Addison's disease in a randomized, double blind trial

Dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEAS) are adrenal precursors of steroid biosynthesis and centrally acting neurosteroids. Glucocorticoid and mineralocorticoid deficiencies in Addison's disease require life-long hormone replacement, but the associated failure of DHEA synthesis is not corrected. We conducted a randomized, double blind study in which 39 patients with Addison's disease received either 50 mg oral DHEA daily for 12 weeks, followed by a 4-week washout period, then 12 weeks of placebo, or vice versa. After DHEA treatment, levels of DHEAS and Delta(4)-androstenedione rose from subnormal to within the adult physiological range. Total testosterone increased from subnormal to low normal with a fall in serum sex hormone-binding globulin in females, but with no change in either parameter in males. In both sexes, psychological assessment showed significant enhancement of self-esteem with a tendency for improved overall well-being. Mood and fatigue also improved significantly, with benefit being evident in the evenings. No effects on cognitive or sexual function, body composition, lipids, or bone mineral density were observed. Our results indicate that DHEA replacement corrects this steroid deficiency effectively and improves some aspects of psychological function. Beneficial effects in males, independent of circulating testosterone levels, suggest that it may act directly on the central nervous system rather than by augmenting peripheral androgen biosynthesis. These positive effects, in the absence of significant adverse events, suggest a role for DHEA replacement therapy in the treatment of Addison's disease.

Cytokine gene polymorphisms in autoimmune thyroid disease

Susceptibility to the autoimmune thyroid diseases, Graves' disease (GD) and autoimmune hypothyroidism (AIH), depends on a complex interaction between environmental and genetic factors. The human leukocyte antigen and cytotoxic T lymphocyte-associated-4 regions appear to influence susceptibility to disease, but the effect is not major, and the other genes remain unknown. Cytokines are crucial in the regulation of immune and inflammatory responses and therefore are potential candidate genes for autoimmune thyroid disease. In a case-control study, using a unified method of genotyping, we have examined 15 polymorphisms in 9 cytokine genes in 215 patients with autoimmune thyroid disease (GD, 138; AIH, 77) and 101 normal controls. Polymorphisms in the genes for interleukin-1alpha (IL-1alpha), IL-1beta, IL-1 receptor antagonist, IL-1 receptor 1, IL-4, IL-4 receptor, IL-6, IL-10, and transforming growth factor-beta were investigated. Genotyping was performed using the PCR and sequence-specific primers. Analysis showed a reduced frequency of the variant t allele in the IL-4 promoter polymorphism (position 590) in patients with GD and in the entire patient group (GD and AIH) compared with the control group [corrected P (Pc) = 0.00004 and Pc < 0.00001 for GD and all patients, respectively]. This was reflected in a reduction in the heterozygote genotype in the patient groups compared to the controls [c/t heterozygotes GD, 12%; Pc = 0.06, odds ratio, 0.4 (95% confidence interval, 0.2-0.7); all patients, 11%; Pc = 0.008; odds ratio, 0.4 (95% confidence interval, 0.2-0.7); control subjects, 23%]. There were no significant differences between the study groups for the other polymorphisms examined, and subgroup analysis revealed no association with clinical parameters of disease. These results suggest that an IL-4 variant or a closely linked gene has a modest protective effect against the development of autoimmune thyroid disease, particularly GD. This variation in the IL-4 gene may provide further clues to the pathogenesis of autoimmune thyroid disease and other organ-specific autoimmune diseases. Furthermore, these results suggest that subtle variation in immunoregulatory genes may be associated with autoimmune disease states.

High-resolution landmark framework for the sequence-ready mapping of Xq23-q26.1

We have established a landmark framework map over 20-25 Mb of the long arm of the human X chromosome using yeast artificial chromosome (YAC) clones. The map has approximately one landmark per 45 kb of DNA and stretches from DXS7531 in proximal Xq23 to DXS895 in proximal Xq26, connecting to published framework maps on its proximal and distal sides. There are three gaps in the framework map resulting from the failure to obtain clone coverage from the YAC resources available. Estimates of the maximum sizes of these gaps have been obtained. The four YAC contigs have been positioned and oriented using somatic-cell hybrids and fluorescence in situ hybridization, and the largest is estimated to cover approximately 15 Mb of DNA. The framework map is being used to assemble a sequence-ready map in large-insert bacterial clones, as part of an international effort to complete the sequence of the X chromosome. PAC and BAC contigs currently cover 18 Mb of the region, and from these, 12 Mb of finished sequence is available.

The effects of pathophysiological increments in brain natriuretic peptide in left ventricular systolic dysfunction

Plasma levels of brain natriuretic peptide (BNP) are raised in patients with left ventricular impairment and may play a role in the adaptation to left ventricular impairment. Manipulation of BNP levels may have therapeutic potential. The effects of BNP have not been well studied in patients with left ventricular impairment. We studied the effects of low-dose BNP infusion, reproducing the increment in plasma BNP seen with progression from mild to severe heart failure in patients with impaired left ventricular systolic function. BNP was infused in a placebo-controlled, single-blind, crossover design at a rate of 3.3 pmol x kg(-1) x min(-1) over 4 hours to 8 patients with a history of congestive heart failure and persistent impairment of left ventricular systolic function (left ventricular ejection fraction <35%). Endocrine, renal, and hemodynamic effects were measured. Compared with time-matched placebo-control, BNP infusion decreased mean systemic arterial pressure (peak decrease, 17.1 mm Hg; P=.04), mean pulmonary artery pressure (peak decrease, 6.1 mm Hg; P=.007), mean pulmonary capillary wedge pressure (peak decrease, 5.5 mm Hg; P=.04), and systemic vascular resistance (peak decrease, 1400 dyne s(-1) cm(-5); P=.015), but cardiac output and heart rate were unchanged. Urinary volume and urinary excretion of sodium and potassium were not altered. BNP infusion increased plasma cGMP (2.3-fold change, P=.002). Plasma atrial natriuretic peptide levels were increased for the first hour of BNP infusion (peak increase, 11.5 pmol/L; P=.005). Plasma aldosterone levels were unchanged during but increased over time-matched control levels after the end of the BNP infusion (peak increase, 90 pmol/L; P=.02). Plasma renin activity and cortisol and catecholamine levels were unchanged. Low-dose infusion of BNP causes favorable hemodynamic changes and relative neurohormonal suppression but has attenuated renal effects in patients with impaired left ventricular systolic function.

Immunoreactive amino-terminal pro-brain natriuretic peptide (NT-PROBNP): a new marker of cardiac impairment

OBJECTIVE

Human brain natriuretic peptide-32 (BNP) (i.e. proBNP(77-108)), the mature form of BNP and secreted predominantly by the cardiac ventricle, is formed from a high molecular weight precursor, proBNP(1-108). We have recently identified the aminoterminal form proBNP(1-76) (NT-proBNP) in human plasma but its source, metabolism and production in circulatory disorders are unknown. We have investigated the relationship between immunoreactive (IR) NT-proBNP and BNP-32 in normal and hypertensive subjects and in patients with cardiac impairment, as well as the regional plasma concentrations in patients undergoing routine cardiac catheterization.

DESIGN AND PATIENTS

Plasma hormone measurements were made in 26 normal subjects, 20 subjects with untreated mild hypertension and 111 treated patients with a history of coronary heart disease and documented cardiac impairment (left ventricular election fraction (LVEF) < 45% (mean 29%); 25 NYHA Class I, 65 Class II and 21 Class III). Regional blood sampling from the femoral artery, femoral vein, renal vein and coronary sinus was undertaken in 14 patients presenting for left and right cardiac catheterization studies in the course of standard investigation for a range of cardiac disorders.

MEASUREMENTS

Plasma samples were assayed for IR NT-proBNP and IR BNP-32 (and atrial natriuretic peptide (ANP) in the regional blood samples). In the patients with cardiac impairment, LVEF was determined by gated radionuclide ventriculography, exercise capacity was measured using a modified Naughton multistage protocol and creatinine clearance was calculated from plasma creatinine, age and weight. In the regional study, extraction ratios across the kidney and lower limb (and step-ups across the heart) were calculated from plasma peptide concentrations.

RESULTS

In normal subjects mean IR NT-proBNP levels (10.8 +/- 1.3 pmol/L) were similar to levels of IR BNP-32 (9.7 +/- 0.5 pmol/L). In hypertensive patients the levels of IR NT-proBNP and IR BNP-32 tended to be higher than but were not significantly different from normal subjects. Both IR NT-proBNP and IR BNP-32 were raised in NYHA Classes I, II and III compared with normals (P < 0.001 for all) with higher levels of both BNP forms seen with increasing cardiac impairment. The levels of IR NT-proBNP were greater than IR BNP-32 in all NYHA Classes (P < 0.001) for all). Overall, the levels of IR NT-proBNP (129 +/- 12 pmol/L) were 4-fold higher than concomitant BNP-32 levels (29 +/- 2 pmol/L). Multivariate analysis showed that LVEF, exercise test time and creatinine clearance were independent predictors of IR NT-proBNP. In all study groups, the levels of IR NT-proBNP and IR BNP-32 levels were highly correlated. Regional plasma sampling showed similar step-ups in IR NT-proBNP and IR BNP-32 levels across the heart, together with similar extraction of both BNP forms across the kidney and lower limb. For both BNP forms, these changes across tissues were significantly less than for ANP.

CONCLUSIONS

Plasma levels of immunoreactive amino terminal-proBNP are raised in cardiac impairment, including NYHA Class I, and rise with increasing cardiac decompensation. Metabolism and tissue uptake of immunoreactive amino terminal-proBNP and immunoreactive BNP-32 appear similar. In cardiac impairment the proportional and absolute increment above normal levels of the aminoterminal BNP peptide exceeds that for BNP-32 and suggest that amino terminal-proBNP may be a more discerning marker of early cardiac dysfunction than BNP-32.

The role of the circulation in processing pro-brain natriuretic peptide (proBNP) to amino-terminal BNP and BNP-32

Human proBNP (purified from cardiac tissue) was incubated at 37 degrees C in whole blood, serum and plasma and the products analyzed by size exclusion high pressure liquid chromatography and radioimmunoassay (RIA). In addition to RIAs for BNP-32 and NT-proBNP(1-13), a newly developed RIA for proBNP(62-76) was also used to identify the peptides. Incubation with serum resulted in the formation of a 9 kDa and a 3 kDa peptide, consistent with the N-terminal and the C-terminal peptides of the propeptide. Minimal processing of proBNP was seen in blood or plasma, suggesting that the circulation does not play a major role in the activation of proBNP. Analysis of degradation products of human proBNP using site directed specific antisera indicates that removal of N-terminal amino acids from proBNP occurs in serum. These findings support the view that the "high molecular weight BNP-32" previously identified in human plasma comprises amino-terminal deleted forms, and is unlikely to be intact proBNP(1-108).

Differing biological effects of equimolar atrial and brain natriuretic peptide infusions in normal man

Atrial natriuretic peptide (ANP) and Brain natriuretic peptide (BNP) are cardiac hormones with similar actions and potency in humans yet with distinctly different effects on plasma cyclic guanosine monophosphate (cGMP). Because most biological actions of natriuretic peptides are thought to be mediated by the guanylate cyclase (G-C) receptors via cGMP, we have compared the biological and G-C-stimulating effects of equimolar infusions of ANP and BNP (2 pmol/kg.min), or vehicle control, on renal, hormonal and hemodynamic function in 8 normal subjects. In addition, the modulating effects of ANP and BNP on the biological actions of infused angiotension II (AngII) were studied. During ANP infusions, plasma ANP concentration increased from 8.8 +/- 0.7 pmol/L to 34 +/- 3 pmol/L at 120 min. Similar increments in plasma BNP occurred during BNP infusions (7.3 +/- 0.6 pmol/L preinfusion, 37 +/- 1 pmol/L at 120 min). Increase in plasma cGMP during ANP infusions was 4-fold that observed during BNP infusions yet natriuresis, contraction in plasma volume, and inhibition of plasma aldosterone were comparable. By contrast, ANP (but not BNP) significantly inhibited the plasma aldosterone response to AngII (P < 0.001). The pressor response to AngII was unaltered by ANP or BNP. Thus, at plasma ANP/BNP levels observed in mild heart failure, ANP is more potent than BNP in inhibiting the aldosterone response to AngII. Comparable natriuresis and inhibition of basal aldosterone is seen, despite much less stimulation of plasma cGMP by BNP, suggesting a different mechanism of hormone action-possibly via non-G-C receptor pathways.

Regional anesthesia in foot and ankle surgery

A method of regional anesthesia use in forefoot and midfoot surgery is described. Careful identification of the peripheral sensory nerves allows for effective anesthesia using bupivacaine and lidocaine in addition to sedation for comfort. A review of 355 patients showed that 98% received an effective surgical block of the sensory nerves. Complications were found to be minimal and patient satisfaction was high. This method provides a safe and effective anesthesia alternative for foot and ankle surgery.

Interactions of atrial and brain natriuretic peptides at pathophysiological levels in normal men

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are both circulating plasma hormones that are secreted by the heart and have similar physiological effects. We have shown previously that abrupt increases in plasma BNP in normal humans impair the clearance of ANP from plasma and result in additive physiological effects. Because large increases in plasma ANP are reported to have no effect on plasma BNP levels in patients with heart failure, we have studied ANP-BNP interactions in eight normal male subjects receiving background infusions of BNP (2 pmol.kg-1.min-1 for 5 h). Each subject also received a coinfusion of ANP ("active" day, 2 pmol.kg-1.min-1 for 2 h) or vehicle ("placebo" day) using a balanced random order, single-blind design. Metabolic clearance rate of ANP (mean 4.1 +/- 0.6 l/min) and disappearance rate from the plasma (t1/2 3.4 +/- 0.3 min) were similar to values measured previously in the absence of exogenous BNP. In contrast, steady-state plasma BNP levels were reversibly increased (mean BNP increment 10 pmol/l) during the administration of ANP (P = 0.038). Associated with these changes were significant (additive) physiological effects. Thus the addition of ANP increased plasma and urine guanosine 3',5'-cyclic monophosphate (P < 0.001 for both) and lowered systolic blood pressure (P = 0.049). When ANP was coinfused, significant differences were also observed in urine volume (P = 0.001) and sodium excretion (P = 0.043) between the infusion period (when urine volume and sodium excretion were enhanced) and postinfusion period (when values decreased). Taken together, our findings of similar interactions between ANP-BNP and BNP-ANP infusions occurring at pathophysiological concentrations of these two peptides, suggest that the interactions result from dissociation of prebound hormone, presumably from biological or clearance receptors.

The amino-terminal portion of pro-brain natriuretic peptide (Pro-BNP) circulates in human plasma

Using an antiserum raised in rabbits to a synthetic human brain natriuretic peptide (BNP) N-terminal fragment [ProBNP(1-13)], a single large molecular weight (MW) N-terminal form of ProBNP has been identified in human plasma. Sep-pak extracts of plasma, drawn from patients with congestive heart failure and subjected to size exclusion and reverse phase high pressure liquid chromatography (HPLC) coupled to radioimmunoassay (RIA) revealed a single large immunoreactive (ir-) peak which was not detected in assays of BNP-32 [ProBNP(77-108)]. This material has a MW of 8600--similar to that expected for the complete N-terminal portion of ProBNP(1-76). Previously reported high MW BNP forms, cross reacting with BNP-32 antisera, were not detected using the N-terminal antisera, indicating that this material is unlikely to be intact ProBNP(1-108). In patients with congestive heart failure plasma ir-levels of N-terminal ProBNP were greatly raised compared to normal subjects and were up to ninefold higher than ir-BNP-32 values.

Carboxyfluorescein (CFSE) labelling of hepatocytes for short-term localization following intraportal transplantation

Renewed interest in the transplantation of isolated hepatocytes into the liver as a potential therapy for liver disease has stimulated the development of methods for the identification of donor cells within the recipient organ. We describe a method for cellular tagging and in vivo identification of intraportally transplanted hepatocytes using an intracellular fluorescent dye, 5(6)-carboxyfluorescein diacetate, succinimidyl-ester (CFSE). Rat and porcine hepatocytes were isolated and labelled with CFSE. The optimal conditions for labelling consisted of a buffered saline suspension of hepatocytes (5 x 10(6) cells/mL) in 20.0 microM CFSE incubated for 15 min at 37 degrees C. In vitro, labelled hepatocytes were cultured either on fibronectin-coated chamber slides or in culture flasks. Cultures were evaluated in situ by fluorescence photomicrography or by fluorescence-activated cell sorting (FACS) after cell detachment. Cell viability was assessed serially and cultured, labelled hepatocytes retained the dye for up to 3 wk (last day of study). CFSE did not effect hepatocyte viability and there was no evidence of intercellular diffusion of the dye. In vivo, syngeneic Lewis rats underwent selective portal vein infusion of freshly isolated, labelled hepatocytes (2.0 x 10(7) cells/2.0 mL saline/animal) into the posterior liver lobes. All recipients were sacrificed 48 h and 96 h later and their livers examined. Transplanted hepatocytes were identified by fluorescence microscopy in tissue sections and by FACS following collagenase digestion of the liver tissue. CFSE persisted in a population of viable, engrafted hepatocytes. FACS analysis demonstrated that 9 +/- 3% of the hepatocytes in the posterior liver lobes were labelled 48 and 96 h after transplantation. At 96 h following transplantation, multiple engrafted hepatocytes could be observed by fluorescence microscopy around the central veins. CFSE labelling allows for both in vitro identification and in vivo localization of donor hepatocytes. Furthermore, it appears to be more stable and specific for labelling hepatocytes than other tested dyes (especially DiI).

Bioactivity and metabolism of C-type natriuretic peptide in normal man

C-Type natriuretic peptide (CNP) is a recently identified member of the natriuretic peptide family with potent vasodepressor activity in experimental animals. Specific CNP receptors and gene transcripts have been identified in human vascular tissues, but the bioactivity and metabolism of CNP in humans are unknown. Accordingly, we have studied the renal, hormonal, and hemodynamic responses in nine normal men (seated, nonfasting) receiving a morning infusion (2 h) of synthetic human CNP-22 (5 pmol/kg.min) or placebo in single blind, random order. To determine the vasodepressor action, the effect of a second identical (afternoon) infusion on the pressor and hormone responses to angiotensin-II (2, 4, and 8 ng/kg.min each for 30 min) was also studied. In the morning infusion, plasma CNP increased from undetectable baseline levels to plateau levels (mean, 60 +/- 6 pmol/L) at 30-120 min. The mean MCR was 4.8 +/- 0.7 L/min, and the t 1/2 (plasma) was 2.6 min. Compared with the effects of placebo, there were significant increases in plasma cGMP (P = 0.001) and plasma atrial natriuretic peptide (ANP; P = 0.02) and a significant decrease in plasma aldosterone (P = 0.007). No significant hemodynamic action or natriuresis was observed. During coinfusion of angiotensin-II, the expected pressor and aldosterone responses were not significantly altered by CNP. In contrast to atrial and brain natriuretic peptide, short term infusion of CNP in humans, achieving supraphysiological levels in plasma, are not vasodepressor or natriuretic. Increases in plasma ANP and plasma cGMP and inhibition of aldosterone may be due in part to competitive displacement by CNP of ANP in common degradative pathways.

Histoplasma capsulatum. Isolation from an Australian cave environment and from a patient

The fungus Histoplasma capsulatum, although commonly found in bat-frequented caves in many countries, has not previously been isolated from that environment in Australia. This report describes the isolation of H. capsulatum from several sources, including cave soil, the organs of mice exposed to the cave environment, and the sputum of a patient clinically diagnosed as having acute pulmonary histoplasmosis after exposure to the cave environment.

Male and female leaders: comparison of performance and behavior patterns

This study examined similarities and differences in behavior patterns and skills of male and female leaders ( n = 32) under four standardized conditions (males supervising males or females, females supervising males or females). Analysis of variance yielded no significant differences between the performance of male and female leaders on both their human-relations and administrative-technical skills. Bales' Interaction Process Analysis showed that female leaders exhibited more release of tension, agreed more often, gave more opinions, and asked for more suggestions than did male leaders. Differences in the measured behaviors of male as well as female subordinates in groups supervised by male and female leaders were found. The behaviors and skills of the leaders were not related to the sex of subordinates.