The Coronary Sinus Reducer; 5-year Dutch experience.

BACKGROUND: Refractory angina is a growing and major health-care problem affecting millions of patients with coronary artery disease worldwide. The Coronary Sinus Reducer (CSR) is a device that may be considered for the relief of symptoms of refractory angina. It causes increased venous pressure leading to a dilatation of arterioles and reduced arterial vascular resistance in the sub-endocardium. This study describes the 5­year Dutch experience regarding safety and efficacy of the CSR. METHODS: One hundred and thirty-two patients with refractory angina were treated with the CSR. The primary efficacy endpoint of the study was Canadian Cardiovascular Society (CCS) class improvement between baseline and 6­month follow-up. The primary safety endpoint was successful CSR implantation in the absence of any device-related events. RESULTS: Eighty-five patients (67%) showed improvement of at least 1 CCS class and 43 patients (34%) of at least 2 classes. Mean CCS class improved from 3.17 ± 0.61 to 2.12 ± 1.07 after implantation (P < 0.001). The CSR was successfully implanted in 99% of the patients and only minor complications during implantation were reported. CONCLUSION: The CSR is a simple, safe, and effective option for most patients with refractory angina. However, approximately thirty percent of the patients showed no benefit after implantation. Future studies should focus on the exact underlying mechanisms of action and reasons for non-response to better identify patients that could benefit most from this therapy.

The ethnicity-specific association of biomarkers with the angiographic severity of coronary artery disease.

BACKGROUND: Risk factor burden and clinical characteristics of patients with coronary artery disease (CAD) differ among ethnic groups. We related biomarkers to CAD severity in Caucasians, Chinese, Indians and Malays. METHODS: In the Dutch-Singaporean UNICORN coronary angiography cohort (n = 2033) we compared levels of five cardiovascular biomarkers: N-terminal pro-brain natriuretic peptide (NTproBNP), high-sensitivity C-reactive protein (hsCRP), cystatin C (CysC), myeloperoxidase (MPO) and high-sensitivity troponin I (hsTnI). We assessed ethnicity-specific associations of biomarkers with CAD severity, quantified by the SYNTAX score. RESULTS: Adjusted for baseline differences, NTproBNP levels were significantly higher in Malays than in Chinese and Caucasians (72.1 vs. 34.4 and 41.1 pmol/l, p < 0.001 and p = 0.005, respectively). MPO levels were higher in Caucasians than in Indians (32.8 vs. 27.2 ng/ml, p = 0.026), hsTnI levels were higher in Malays than in Caucasians and Indians (33.3 vs. 16.4 and 17.8 ng/l, p < 0.001 and p = 0.029) and hsTnI levels were higher in Chinese than in Caucasians (23.3 vs. 16.4, p = 0.031). We found modifying effects of ethnicity on the association of biomarkers with SYNTAX score. NTproBNP associated more strongly with the SYNTAX score in Malays than Caucasians (ß 0.132 vs. ß 0.020 per 100 pmol/l increase in NTproBNP, p = 0.032). For MPO levels the association was stronger in Malays than Caucasians (ß 1.146 vs. ß 0.016 per 10 ng/ml increase, p = 0.017). Differing biomarker cut-off levels were found for the ethnic groups. CONCLUSION: When corrected for possible confounders we observe ethnicity-specific differences in biomarker levels. Moreover, biomarkers associated differently with CAD severity, suggesting that ethnicity-specific cut-off values should be considered.

Heart failure with preserved ejection fraction in women: the Dutch Queen of Hearts program.

Heart failure (HF) poses a heavy burden on patients, their families and society. The syndrome of HF comes in two types: with reduced ejection fraction (HFrEF) and preserved ejection fraction (HFpEF). The latter is on the increase and predominantly present in women, especially the older ones. There is an urgent need for mortality-reducing drugs in HFpEF, a disease affecting around 5 % of those aged 65 years and over. HFpEF develops in patients with risk factors and comorbidities such as obesity, hypertension, diabetes, COPD, but also preeclampsia. These conditions are likely to drive microvascular disease with involvement of the coronary microvasculature, which may eventually evolve into HFpEF. Currently, the diagnosis of HFPEF relies mainly on echocardiography. There are no biomarkers that can help diagnose female microvascular disease or facilitate the diagnosis of (early stages of) HFpEF. Recently a Dutch consortium was initiated, Queen of Hearts, with support from the Netherlands Heart Foundation, with the aim to discover and validate biomarkers for diastolic dysfunction and HFpEF in women. These biomarkers come from innovative blood-derived sources such as extracellular vesicles and circulating cells. Within the Queen of Hearts consortium, we will pursue female biomarkers that have the potential for further evolution in assays with point of care capabilities. As a spin-off, the consortium will gain knowledge on gender-specific pathology of HFpEF, possibly opening up novel treatment options.

Plasma extracellular vesicle protein content for diagnosis and prognosis of global cardiovascular disease.

Cardiovascular disease is a major public health problem worldwide. Its growing burden is particularly ominous in Asia, due to increasing rates of major risk factors such as diabetes, obesity and smoking. There is an urgent need for early identification and treatment of individuals at risk of adverse cardiovascular events. Plasma extracellular vesicle proteins are novel biomarkers that have been shown to be useful in the diagnosis, risk stratification and prognostication of patients with cardiovascular disease. Ongoing parallel biobank initiatives in European (the Netherlands) and Asian (Singapore) populations offer a unique opportunity to validate these biomarkers in diverse ethnic groups.

Carotid atherosclerotic plaques stabilize after stroke: insights into the natural process of atherosclerotic plaque stabilization.

OBJECTIVE: Rupture of unstable atherosclerotic plaques is the pathological substrate for acute ischemic events. Underlying cellular and molecular characteristics of plaque rupture have been studied extensively. However, the natural course of symptomatic plaque remodeling after ischemic events is relatively unexplored. METHODS AND RESULTS: Atherosclerotic carotid plaques were obtained from 804 symptomatic (stroke=204 and TIA=426) and asymptomatic (n=174) patients undergoing carotid endarterectomy. The presence of macrophages, smooth muscle cells (SMC), collagen, calcification, and lipid-core size were assessed histologically. At protein level, inflammatory mediators (interleukin [IL]-2, IL-4, IL-5, IL-8, IL-10, IL-12p70, interferon-gamma [INF-gamma], tumor necrosis factor-alpha [TNF-alpha], matrix degrading proteinases (MMPs), and an apoptosis marker (caspase-3) were determined. We associated plaque characteristics with time elapsed between the latest event and surgery. Early after stroke and TIA, plaques revealed an unstable phenotype. After stroke, the content of macrophages decreased significantly with time (P=0.02), whereas SMC content tended to increase. At protein level, IL-6, IL-8 expression levels and caspase activity strongly decreased after stroke or TIA. CONCLUSIONS: Symptomatic carotid lesions remodel into more stable plaques over time after stroke. Changes in IL-6 and IL-8 and caspase preceded the decrease of macrophages. These temporal phenotypic plaque alterations should be taken into account for biomarker and therapeutic target validation studies using human atherosclerotic plaques.

Predictive risk factors for restenosis after remote superficial femoral artery endarterectomy.

OBJECTIVES: Restenosis following remote superficial femoral artery endarterectomy (RSFAE) remains a challenging problem. The determinants predicting failure are lacking. This study investigated patient characteristics with predictive value for restenosis during the first year after RSFAE. DESIGN: A prospective cohort study. MATERIALS AND METHODS: A total of 90 patients post-RSFAE were studied for the occurrence of restenosis (peak systolic velocity ratio >or= 2.5) in the first 12 months postoperatively. At baseline, clinical parameters were recorded. Vessel size was measured on the basis of plaque perimeter in the culprit lesion and lumen diameter on perioperative digital subtraction angiography. RESULTS: In 57 patients (63%), a restenotic lesion was diagnosed within 12 months following surgery. Patients with longer time interval between start of ischaemic walking complaints and RSFAE revealed a significantly higher incidence of restenosis (hazard ratio (HR) = 1.3 (1.05-1.52) per 4 years). Small plaque perimeter and small superficial femoral artery (SFA) diameter on angiography were significantly associated with restenosis (HR = 0.54 (0.34-0.88) per 10 mm and HR = 0.46 (0.27-0.78) per 1.5 mm, respectively). In multivariate analysis, age, duration of ischaemic walking complaints and lumen diameter were independently associated with increased risk of restenosis after RSFAE. CONCLUSIONS: This study provides evidence that age, vessel size and duration of ischaemic walking complaints before RSFAE are predictive values for restenosis after RSFAE.

Frameshift mutants of beta amyloid precursor protein and ubiquitin-B in Alzheimer's and Down patients.

The cerebral cortex of Alzheimer's and Down syndrome patients is characterized by the presence of protein deposits in neurofibrillary tangles, neuritic plaques, and neuropil threads. These structures were shown to contain forms of beta amyloid precursor protein and ubiquitin-B that are aberrant (+1 proteins) in the carboxyl terminus. The +1 proteins were not found in young control patients, whereas the presence of ubiquitin-B+1 in elderly control patients may indicate early stages of neurodegeneration. The two species of +1 proteins displayed cellular colocalization, suggesting a common origin, operating at the transcriptional level or by posttranscriptional editing of RNA. This type of transcript mutation is likely an important factor in the widely occurring nonfamilial early- and late-onset forms of Alzheimer's disease.

[Differences between men and women in the composition of atherosclerotic plaque, as an explanation for the lower success rate of carotid endarterectomy in women]. / Verschillen in samenstelling van de atherosclerotische plaque tussen mannen en vrouwen als verklaring voor het geringere succes van carotisendarteriëctomie bij vrouwen.

OBJECTIVE: To determine whether men and women differ in the histological characteristics of plaque material removed at carotid endarterectomy. DESIGN: Observational and descriptive. METHODS: Carotid endarterectomy plaque specimens obtained from 45 degrees consecutive patients (135 women, 315 men) were assessed for the presence of macrophages, smooth muscle cells, collagen, calcifications, and luminal thrombus by means ofimmunohistochemical staining. The plaques were categorised in 3 phenotypes according to the overall presentation of histological characteristics and the lipid level. Protein was isolated from the plaques to determine the interleukin-6 (IL-6) and IL-8 concentrations and the activity of matrix metalloproteinase-8 (MMP-8) and MMP-9. RESULTS: Atheromatous plaques (> 40% fat) were less frequently observed in women than in men (22 versus 40%; p < 0.001). In addition, more women than men had a low macrophage staining (18 versus 11%; p = 0.05) and strong smooth muscle cell staining (38 versus 24%; p = 0.001). Compared with men, women had a lower plaque concentration of IL-8 and lower MMP-8 activity. The observed differences were most pronounced in the asymptomatic group. An atheromatous plaque occurred in 9% of asymptomatic women compared to 39% ofasymptomatic men (p = 0.02). Moreover, a large proportion of plaques obtained from asymptomatic women showed high smooth muscle cell content (53 versus 30%; p = 0.03) and high collagen content (55 versus 24%; p = 0.003). All relations between gender and plaque characteristics, except for MMP-8, remained the same in a multivariate analysis that was adjusted for clinical presentation and other cardiovascular risk factors. CONCLUSION: Women with a carotid stenosis had more stable plaques than men, independent of clinical presentation and cardiovascular risk profile. Asymptomatic women demonstrated the highest prevalence of stable plaques. These findings may explain why women benefit less from carotid endarterectomy than men.

Identification of genes potentially involved in disease transformation of CML.

In patients with chronic myeloid leukemia (CML) who do not reach a (near) complete cytogenetic response, the disease progresses over several years from an indolent, chronic phase into a rapidly fatal blast crisis. Events that are responsible for this transformation process are largely unknown. To identify changes in gene expression that occurred during the course of the disease, we performed cDNA subtraction on sequentially stored peripheral blood mononuclear cell pellets, collected throughout the course of disease of a single CML patient. In total, 32 differentially expressed sequences were identified, of which 27 corresponded to known genes. On quantitative PCR, eight of these genes, YWHAZ, GAS2, IL8, IL6, PBEF1, CCL4, SAT and MMRN, showed comparable differential expression in additional CML patient samples. This set of genes can be considered as a starting point for further research on causes of disease transformation in CML and may lead to new targets in the treatment of resistant CML.

Toll-like receptor 2 stimulation induces intimal hyperplasia and atherosclerotic lesion development.

BACKGROUND: Toll like receptors (Tlr) are essential in activation of the innate immune system. We recently described that peptidoglycan, an exogenous Tlr2 specific ligand, is present in human atherosclerotic plaques and associated with histological markers for plaque vulnerability. Also, endogenous Tlr2 ligands can be expressed in atherosclerotic tissues. Here, we determined whether Tlr2 stimulation promotes pro-inflammatory cytokine/chemokine production in vitro and augments neointima formation and development of atherosclerotic plaques in vivo. METHODS AND RESULTS: We detected Tlr2 using Western blot and RT-PCR in human coronary arteries and primary adventitial fibroblasts. RNAse protection assay demonstrated significant induction of IL-1, IL-6, IL-8 and MCP-1 mRNA after Tlr2 stimulation in human adventitial fibroblasts in vitro. ELISA demonstrated induction of IL-6, IL-8 and MCP-1. In vivo application of Pam(3)Cys-SK(4), a synthetic Tlr2 ligand, on femoral arteries of C57BL/6 wild type (WT) mice using a peri-adventitial cuff, significantly enhanced neointima formation compared to control arteries. This increased inflammatory response was not observed in Tlr2 knockout (Tlr2-/-) mice. In ApoE knockout mice (ApoE-/-), application of the same Tlr2 ligand led to a significant increase in atherosclerotic plaque development. CONCLUSION: Local arterial Tlr2 stimulation induced neointima and atherosclerotic plaque formation in mouse femoral arteries. Tlr2 stimulation may be an important mediator in arterial occlusive disease.

Cloning and expression of two mRNAs encoding structurally different crustacean hyperglycemic hormone precursors in the lobster Homarus americanus.

The crustacean hyperglycemic hormone (CHH) of the X-organ sinus gland complex is a multifunctional neurohormone primarily involved in the regulation of blood sugar levels. HPLC analysis of lobster sinus glands revealed two CHH-immunoreactive groups, each consisting of two isoforms with identical amino acid sequences and molecular weights. In order to obtain more information concerning the number and sequences of preproCHHs, and to study their expression, we isolated two full-length cDNAs encoding two different CHH preprohormones. Both preprohormone structures consist of a signal peptide, a CHH-precursor-related peptide and a highly-conserved CHH peptide. Expression studies revealed that the X-organ is not the only source of CHH mRNA because the ventral nerve system also expresses this mRNA. Based on these findings and earlier studies on the effect of eyestalk ablation, implantation of thoracic/abdominal ganglia as well as the multifunctionality of CHH, we postulate that CHH, present in the ventral nerve system is a good candidate for a supplementary role in the control of reproduction and molting.

Cloning and sequence analysis of a hypothalamic cDNA encoding a D1c dopamine receptor in tilapia.

Physiological and pharmacological studies have indicated that during acid stress a D1-like dopamine receptor becomes functional on intermediate pituitary melanocyte-stimulating hormone cells of tilapia (Oreochromis mossambicus). As a first step towards physiological expression studies we isolated a D1-like dopamine receptor from a tilapia hypothalamus cDNA library. Construction of a phylogenetic tree of most of the D1-like receptors known in human, rat, Xenopus, goldfish and Drosophila revealed that the here presented clone is most likely the tilapia equivalent of the Xenopus D1c dopamine receptor.

Distribution of Chlamydia pneumoniae in the human arterial system and its relation to the local amount of atherosclerosis within the individual.

BACKGROUND: Chlamydia pneumoniae has been suggested to play a role in the origin of atherosclerosis. We studied the prevalence of C pneumoniae at multiple locations in the arterial system within the same individual. Studying the association between atherosclerosis and C pneumoniae within the individual excludes confounding by interindividual variability. METHODS AND RESULTS: Postmortem, the presence in the intima/plaque and media of C pneumoniae membrane protein was determined by use of a C pneumoniae-specific monoclonal antibody. In 24 individuals, 33 arterial locations were studied (n=738 segments). Area stenosis was determined in adjacent cross sections. In all individuals, immunostaining of C pneumoniae was observed in >/=1 artery. The highest prevalences were observed in the abdominal aorta (67%), internal and common iliac arteries (41%), and coronary arteries (33%). The lowest prevalences were observed in the radial (0%) and cerebral (2%) arteries. Within the individual, area stenosis was larger in cross sections with immunoreactivity compared with cross sections without immunoreactivity (31.0+/-11.9% versus 14.3+/-6.1%, respectively; P:<0.001). In the individual, immunoreactivity was observed in 15+/-10% of the arteries (range, 3% to 45%). Between individuals, the percentage of arteries with immunoreactivity to C pneumoniae was associated with the average area stenosis throughout the arterial system (r(2)=0.56, P:<0.001). CONCLUSIONS: C pneumoniae was mostly observed at locations that are related to clinically relevant features. Within the individual, the distribution of C pneumoniae is associated with the distribution of atherosclerosis. The role of the microorganism in atherosclerotic disease remains to be elucidated.

Carotid atherosclerotic plaque characteristics are associated with microembolization during carotid endarterectomy and procedural outcome.

BACKGROUND AND PURPOSE: During carotid endarterectomy (CEA), microemboli may occur, resulting in perioperative adverse cerebral events. The objective of the present study was to investigate the relation between atherosclerotic plaque characteristics and the occurrence of microemboli or adverse events during CEA. METHODS: Patients (n=200, 205 procedures) eligible for CEA were monitored by perioperative transcranial Doppler. The following phases were discriminated during CEA: dissection, shunting, release of the clamp, and wound closure. Each carotid plaque was stained for collagen, macrophages, smooth muscle cells, hematoxylin, and elastin. Semiquantitative analyses were performed on all stainings. Plaques were categorized into 3 groups based on overall appearance (fibrous, fibroatheromatous, or atheromatous). RESULTS: Fibrous plaques were associated with the occurrence of more microemboli during clamp release and wound closure compared with atheromatous plaques (P=0.04 and P=0.02, respectively). Transient ischemic attacks and minor stroke occurred in 5 of 205 (2.4%) and 6 of 205 (2.9%) patients, respectively. Adverse cerebral outcome was significantly related to the number of microembolic events during dissection (P=0.003) but not during shunting, clamp release, or wound closure. More cerebrovascular adverse events occurred in patients with atheromatous plaques (7/69) compared with patients with fibrous or fibroatheromatous plaques (4/138) (P=0.04). CONCLUSIONS: Intraoperatively, a higher number of microemboli were associated with the presence of a fibrous but not an atheromatous plaque. However, atheromatous plaques were more prevalent in patients with subsequent immediate adverse events. In addition, specifically the number of microemboli detected during the dissection phase were related to immediate adverse events.

Plaque burden, arterial remodeling and plaque vulnerability: determined by systemic factors?

OBJECTIVES: This study was designed to determine whether arterial remodeling and plaque vulnerability are influenced by systemic factors. BACKGROUND: Atherosclerotic luminal narrowing is caused by gradual plaque growth and arterial remodeling. In the acute phase, luminal narrowing may be accelerated by acute thrombus formation, usually precipitated by rupture of a vulnerable plaque. METHODS: Femoral arteries were obtained from elderly individuals at autopsy. Pairs of atherosclerotic femoral arteries from 42 individuals were examined. The arteries were divided in 1-cm intervals. Plaque size, the mode of arterial remodeling and histopathologic characteristics of plaque vulnerability (lipid-rich core and plaque inflammation) were compared between right and left femoral arteries obtained from the same individual. A role for systemic factors was assumed if a phenomenon was equally present in both arteries. RESULTS: There was concordance in average plaque size (r(2) = 0.5, p < 0.001), expansive remodeling (kappa = 0.42, p = 0.007) and occurrence of plaques containing a large lipid-rich core (kappa = 0.60, p = 0.001), but no concordance in plaque inflammation (kappa = 0.067, p = 0.61) between right and left arteries. CONCLUSIONS: These results suggest that not only the amount of atherosclerosis, but also arterial remodeling and lipid deposition in plaques, are influenced by systemic factors. The nonhomogeneous distribution of inflammation in atherosclerotic arteries supports the hypothesis that plaque inflammation is locally affected.

Modulation of collagen turnover in cardiovascular disease.

Collagen fibers are the most abundant components of the extracellular matrix in arteries and myocardium. Disturbances in the collagen turnover (synthesis and degradation) have been linked to inflammatory diseases including cardiovascular pathological syndromes. In the myocardium, changes in collagen turnover may result in ventricle dilatation and subsequent contractile dysfunction. In arteries, collagen synthesis and degradation are associated with the progression of atherosclerotic disease and intimal hyperplasia following injury. Collagen synthesis is tightly regulated at several levels: synthesis of procollagens, suitable folding of polypeptides, secretion and cross-linking of mature fibers. On the other hand, degradation of newly synthesised procollagen and mature collagen fibers depends on the action of Matrix-Metalloproteinases (MMPs). The major role of collagen turnover in cardiovascular disorders has stimulated the search for pharmacological agents that interfere with collagen turnover at different levels. These drugs can theoretically act through modulation of the synthesis of procollagens or by interference with their post-translational modifications. Another group of pharmacological agents inhibit collagen breakdown (MMP inhibitors). Beneficial effects of compounds that target collagen metabolism have been reported. Unfortunately, many of these compounds also give rise to serious adverse effects due to interference with vital biological processes in which collagen plays an important role. In this paper, we will review cardiovascular diseases in which altered local collagen turnover is a key feature. Subsequently, the effect of compounds that have been developed and tested to modulate collagen synthesis, cross-linking or breakdown will be discussed.

Arterial remodeling in atherosclerosis, restenosis and after alteration of blood flow: potential mechanisms and clinical implications.

Arterial remodeling is currently being recognized as an important determinant in vascular pathology in which narrowing of the lumen is the predominant feature. Not only expansive remodeling (enlargement), but also constrictive remodeling (shrinkage) is observed in de novo atherosclerosis, in restenosis and in transplant vasculopathy. Expansive remodeling prevents and constrictive remodeling enhances luminal narrowing by plaque formation or intimal hyperplasia. The mechanisms of the opposite remodeling modes is unknown. Insight into the processes that determine the direction of local arterial remodeling may help to develop new strategies to prevent arterial occlusive disease. In the present paper the current status of research in the field of arterial remodeling in cardiovascular disease is reviewed. Mechanisms of arterial remodeling, potential interventions to influence the mode of remodeling as well as the methodological limitations of remodeling studies are discussed.

Attenuation of the polypeptide 7B2, prohormone convertase PC2, and vasopressin in the hypothalamus of some Prader-Willi patients: indications for a processing defect.

7B2 is a neuroendocrine chaperone interacting with the prohormone convertase PC2 in the regulated secretory pathway. Its gene is located near the Prader-Willi syndrome (PWS) region on chromosome 15. In a previous study we were able to show 7B2 immunoreactivity in the supraoptic nucleus (SON) or the paraventricular nucleus (PVN) in only three of five PWS patients. Here we report that in contrast with five other PWS patients, the neurons in the hypothalamic SON and PVN of the two 7B2-immunonegative PWS patients also failed to show any reaction using two antibodies directed against processed vasopressin (VP). On the other hand, even these two cases reacted normally with five antibodies that recognize different parts of the VP precursor. This finding pointed to a processing defect. Indeed, the same patients had no PC2 immunoreactivity in the SON or PVN, whereas PC1 immunoreactivity was only slightly diminished. In conclusion, in the VP neurons of two PWS patients, greatly reduced amounts of 7B2 and PC2 are present, resulting in diminished VP precursor processing.

The vasopressin precursor is not processed in the hypothalamus of Wolfram syndrome patients with diabetes insipidus: evidence for the involvement of PC2 and 7B2.

Wolfram syndrome (WS) is characterized by optic atrophy, insulin-dependent diabetes mellitus, vasopressin (VP)-sensitive diabetes insipidus, and neurosensory hearing loss. Here we report a disturbance in VP precursor processing in the supraoptic and paraventricular nuclei of WS patients. In these patients with diabetes insipidus we could hardly detect any cellular immunoreactivity for processed VP in the supraoptic and paraventricular nuclei. On the other hand, in the paraventricular nucleus a considerable number of cells immunoreactive for the VP precursor were present. In addition, the proprotein convertase PC2 and the molecular chaperone 7B2 were absent. As expression of PC2 and 7B2 was detected in the nearby nucleus basalis of Meynert of one WS patient and in the anterior lobe of the other WS patient, the absence of the two proteins in the paraventricular nucleus was not due to mutations in their genes. These results indicate that in WS patients with diabetes insipidus, not only does VP neuron loss occur in the supraoptic nucleus, but there is also a defect in VP precursor processing.

Molecular cloning of crustacean putative molt-inhibiting hormone (MIH) precursor.

A cDNA encoding the complete precursor of the putative molt-inhibiting hormone (MIH) of the shore crab, Carcinus maenas, was isolated and sequenced. The precursor consists of a putative 35 amino acid signal peptide and the 78 amino acid mature MIH. The deduced MIH amino acid sequence is in complete agreement with the sequence previously determined by Edman degradation. In situ hybridization revealed MIH-expression in a subpopulation of large neurosecretory perikarya of the medulla terminalis X-organ in the eyestalk.