Impact of epicardial adipose tissue accumulation on left ventricular mass and hypertrophy in non-obstructive coronary artery disease

Introduction

Increased left ventricular mass index (LVMi) and left ventricular hypertrophy (LVH) by echocardiography are common in obesity and important cardiovascular risk predictors associated with myocardial ischemia in non-obstructive coronary artery disease (CAD). Accumulation of epicardial adipose tissue (EAT) suggest a possible direct impact on LVMi and LVH.

Purpose

To explore the association between EAT volume, LVMi and LVH in patients with chest pain and non-obstructive CAD.

Methods

We included 129 patients with chest pain and non-obstructive CAD (<50% stenosis) by coronary computed tomography (CT) angiography. EAT volume was quantified using a semiautomatic analysis software on non-contrast cardiac CT images. Patients were grouped according to EAT volume, where high EAT volume was adjudicated when EAT volume was in the highest tertile (≥125 ml). Left ventricular mass was assessed by echocardiography, calculated by the Devereux formula and indexed for height in the allometric power of 2.7 (LVMi). LVH was defined as LVMi >46.7 g/m2.7 in women and >49.2 g/m2.7 in men. Coronary artery plaque burden was assessed as calcium score and segment involvement score on coronary CT angiography.

Results

High EAT volume was more common in men with higher BMI, waist circumference, serum triglycerides and higher prevalence of hypertension and obesity (all p<0.05). Age, coronary calcium score and coronary artery segment involvement score did not differ between groups. Patients with high EAT volume had higher LVMi compared to those with low EAT volume (42.5 g/m2.7 vs. 36.1 g/m2.7, p=0.003), while there was no difference in EAT volume among patients with or without LVH. In univariable logistic regression analysis, high EAT volume was associated with higher LVMi (OR 1.05 [95% CI 1.01–1.10] per g/m2.7, p=0.015). After adjusting for hypertension and obesity in a multivariable model, higher LVMi remained significantly associated with high EAT volume (Model 1, Table 1), but the association was attenuated after adjusting for sex (Model 2, Table 1).

Conclusion

High EAT volume was associated with increased LVMi in patients with non-obstructive CAD, independent of hypertension and obesity, while there was no association with LVH. This suggest that direct infiltration of adipose tissue in the myocardium may contribute to the development of increased LVMi.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Western Norwegian Regional Health Authorities Table 1

P2647Impact of hypertension on extent of non-obstructive coronary artery disease (The NORIC registry)

Background

In non-obstructive coronary artery disease (CAD), increasing extent of disease is associated with a worse prognosis. Statin therapy has been suggested to improve the prognosis. Whether hypertension, a modifiable CV risk factor, affects the extent of non-obstructive CAD in patients with stable angina is less explored.

Purpose

To assess the association between hypertension and extent of non-obstructive coronary artery disease.

Methods

We identified 1117 patients (mean age 62±10 years, 48% women) from the Norwegian Registry for Invasive Coronary angiography (NORIC). All subjects had stable angina and non-obstructive CAD defined as 1–49% stenosis in any coronary artery segment by coronary computed tomography angiography (CCTA). The extent of non-obstructive CAD was assessed as coronary artery segment involvement score (SIS) on CCTA. Extensive non-obstructive CAD was defined as SIS≥4.

Results

Hypertension was present in 44% and patients with hypertension were older with a higher prevalence of diabetes, obesity, smoking and statin therapy (all p<0.05). Coronary artery SIS and calcium score were higher in patients with hypertension compared to those without hypertension, (3.1±2.0 vs. 2.6±1.7, p<0.001 and 41 (116) vs. 32 (91) HU, p<0.05), respectively. There was no significant sex difference in the prevalence of hypertension. In univariable analysis, hypertension, age, calcium score and statin treatment were significantly associated with extensive non-obstructive CAD (Table). Hypertension remained a strong, independent predictor of extensive non-obstructive CAD after adjusting for other known covariables (Table).

Table 1. Covariables of extensive non-obstructive CAD in univariable and multivariable logistic regression analysis Univariable analysis Multivariable analysis OR 95% CI p-value OR 95% CI p-value Hypertension 1.57 1.21–2.04 0.001 1.47 1.03–2.10 0.035 Age 1.06 1.05–1.08 <0.001 1.04 1.01–1.06 0.001 Calcium score 1.02 1.01–1.02 <0.001 1.01 1.01–1.02 <0.001 Statin treatment 1.34 1.03–1.75 0.029 1.20 0.83–1.70 0.341 Smoking 1.33 1.00–1.77 0.052 1.24 0.86–1.78 0.251 Diabetes mellitus 1.34 0.86–2.12 0.191 1.10 0.57–2.09 0.781 Obesity 1.03 0.76–1.41 0.839 1.19 0.79–1.80 0.425

Conclusions

Hypertension is associated with extensive non-obstructive CAD in patients with stable angina, suggesting that early and aggressive antihypertensive treatment may impact disease progression.

The impact of logging roads on dung beetle assemblages in a tropical rainforest reserve

The demand for timber products is facilitating the degradation and opening up of large areas of intact habitats rich in biodiversity. Logging creates an extensive network of access roads within the forest, yet these are commonly ignored or excluded when assessing impacts of logging on forest biodiversity. Here we determine the impact of these roads on the overall condition of selectively logged forests in Borneo, Southeast Asia. Focusing on dung beetles along > 40 km logging roads we determine: (i) the magnitude and extent of edge effects alongside logging roads; (ii) whether vegetation characteristics can explain patterns in dung beetle communities, and; (iii) how the inclusion of road edge forest impacts dung beetle assemblages within the overall logged landscape. We found that while vegetation structure was significantly affected up to 34 m from the road edge, impacts on dung beetle communities penetrated much further and were discernible up to 170 m into the forest interior. We found larger species and particularly tunnelling species responded more than other functional groups which were also influenced by micro-habitat variation. We provide important new insights into the long-term ecological impacts of tropical logging. We also support calls for improved logging road design both during and after timber extraction to conserve more effectively biodiversity in production forests, for instance, by considering the minimum volume of timber, per unit length of logging road needed to justify road construction. In particular, we suggest that governments and certification bodies need to highlight more clearly the biodiversity and environmental impacts of logging roads.

Land-sharing versus land-sparing logging: reconciling timber extraction with biodiversity conservation

Selective logging is a major driver of rainforest degradation across the tropics. Two competing logging strategies are proposed to meet timber demands with the least impact on biodiversity: land sharing, which combines timber extraction with biodiversity protection across the concession; and land sparing, in which higher intensity logging is combined with the protection of intact primary forest reserves. We evaluate these strategies by comparing the abundances and species richness of birds, dung beetles and ants in Borneo, using a protocol that allows us to control for both timber yield and net profit across strategies. Within each taxonomic group, more species had higher abundances with land-sparing than land-sharing logging, and this translated into significantly higher species richness within land-sparing concessions. Our results are similar when focusing only on species found in primary forest and restricted in range to Sundaland, and they are independent of the scale of sampling. For each taxonomic group, land-sparing logging was the most promising strategy for maximizing the biological value of logging operations.

Selective‐logging and oil palm: multitaxon impacts, biodiversity indicators, and trade‐offs for conservation planning

Strong global demand for tropical timber and agricultural products has driven large-scale logging and subsequent conversion of tropical forests. Given that the majority of tropical landscapes have been or will likely be logged, the protection of biodiversity within tropical forests thus depends on whether species can persist in these economically exploited lands, and if species cannot persist, whether we can protect enough primary forest from logging and conversion. However, our knowledge of the impact of logging and conversion on biodiversity is limited to a few taxa, often sampled in different locations with complex land-use histories, hampering attempts to plan cost-effective conservation strategies and to draw conclusions across taxa. Spanning a land-use gradient of primary forest, once- and twice-logged forests, and oil palm plantations, we used traditional sampling and DNA metabarcoding to compile an extensive data set in Sabah, Malaysian Borneo for nine vertebrate and invertebrate taxa to quantify the biological impacts of logging and oil palm, develop cost-effective methods of protecting biodiversity, and examine whether there is congruence in response among taxa. Logged forests retained high species richness, including, on average, 70% of species found in primary forest. In contrast, conversion to oil palm dramatically reduces species richness, with significantly fewer primary-forest species than found on logged forest transects for seven taxa. Using a systematic conservation planning analysis, we show that efficient protection of primary-forest species is achieved with land portfolios that include a large proportion of logged-forest plots. Protecting logged forests is thus a cost-effective method of protecting an ecologically and taxonomically diverse range of species, particularly when conservation budgets are limited. Six indicator groups (birds, leaf-litter ants, beetles, aerial hymenopterans, flies, and true bugs) proved to be consistently good predictors of the response of the other taxa to logging and oil palm. Our results confidently establish the high conservation value of logged forests and the low value of oil palm. Cross-taxon congruence in responses to disturbance also suggests that the practice of focusing on key indicator taxa yields important information of general biodiversity in studies of logging and oil palm.

Does logging and forest conversion to oil palm agriculture alter functional diversity in a biodiversity hotspot?

Forests in Southeast Asia are rapidly being logged and converted to oil palm. These changes in land-use are known to affect species diversity but consequences for the functional diversity of species assemblages are poorly understood. Environmental filtering of species with similar traits could lead to disproportionate reductions in trait diversity in degraded habitats. Here, we focus on dung beetles, which play a key role in ecosystem processes such as nutrient recycling and seed dispersal. We use morphological and behavioural traits to calculate a variety of functional diversity measures across a gradient of disturbance from primary forest through intensively logged forest to oil palm. Logging caused significant shifts in community composition but had very little effect on functional diversity, even after a repeated timber harvest. These data provide evidence for functional redundancy of dung beetles within primary forest and emphasize the high value of logged forests as refugia for biodiversity. In contrast, conversion of forest to oil palm greatly reduced taxonomic and functional diversity, with a marked decrease in the abundance of nocturnal foragers, a higher proportion of species with small body sizes and the complete loss of telecoprid species (dung-rollers), all indicating a decrease in the functional capacity of dung beetles within plantations. These changes also highlight the vulnerability of community functioning within logged forests in the event of further environmental degradation.

Elevational distribution and conservation biogeography of phanaeine dung beetles (Coleoptera: Scarabaeinae) in Bolivia

Insect macroecology and conservation biogeography studies are disproportionately scarce, especially in the Neotropics. Dung beetles are an ideal focal taxon for biodiversity research and conservation. Using distribution and body size data on the ecologically important Phanaeini, the best-known Neotropical dung beetle tribe, we determined elevational patterns of species richness, endemism, body size, and elevational range in Bolivia, specifically testing Bergmann’s and Rapoport’s rule. Richness of all 39 species and of 15 ecoregional endemics showed a hump-shaped pattern peaking at 400 m, but overall declined strongly with elevation up to 4000 m. The relationship between endemic and total species richness appeared to be curvilinear, providing only partial support for the null hypothesis that species-rich areas are more likely to be centers of endemism by chance alone. An elevational increase in the proportion of ecoregional endemics suggests that deterministic factors also appear to influence endemism in the Andes. When controlling for the effect of area using different species-area relationships, the statistically significant richness peak became more pronounced and shifted upslope to 750 m. Larger species did not have higher elevational mid-points, and mean body size decreased significantly with elevation, contradicting Bergmann’s rule. Rapoport’s rule was supported: species with higher elevational mid-points had broader elevational ranges, and mean elevational range increased significantly with elevation. The elevational decrease of phanaeine richness is in accordance with studies that demonstrated the combined influence of temperature and water availability on species diversity, but also is consistent with niche conservatism. For invertebrates, confirmation of Rapoport’s and refutation of Bergmann’s rule appear to be scale-invariant general patterns. Analyses of biogeographic patterns across elevational gradients can provide important insights for identifying conservation priorities. Phanaeines with narrow elevational ranges on isolated low-elevation mountains in eastern Bolivia are at greatest climate-change related extinction risk from range-shift gaps and mountaintop extinctions.

Reduced-impact logging and biodiversity conservation: a case study from Borneo

A key driver of rain forest degradation is rampant commercial logging. Reduced-impact logging (RIL) techniques dramatically reduce residual damage to vegetation and soils, and they enhance the long-term economic viability of timber operations when compared to conventionally managed logging enterprises. Consequently, the application of RIL is increasing across the tropics, yet our knowledge of the potential for RIL also to reduce the negative impacts of logging on biodiversity is minimal. We compare the impacts of RIL on birds, leaf-litter ants, and dung beetles during a second logging rotation in Sabah, Borneo, with the impacts of conventional logging (CL) as well as with primary (unlogged) forest. Our study took place 1-8 years after the cessation of logging. The species richness and composition of RIL vs. CL forests were very similar for each taxonomic group. Both RIL and CL differed significantly from unlogged forests in terms of bird and ant species composition (although both retained a large number of the species found in unlogged forests), whereas the composition of dung beetle communities did not differ significantly among forest types. Our results show little difference in biodiversity between RIL and CL over the short-term. However, biodiversity benefits from RIL may accrue over longer time periods after the cessation of logging. We highlight a severe lack of studies investigating this possibility. Moreover, if RIL increases the economic value of selectively logged forests (e.g., via REDD+, a United Nations program: Reducing Emissions from Deforestation and Forest Degradation in Developing Countries), it could help prevent them from being converted to agricultural plantations, which results in a tremendous loss of biodiversity.

Degraded lands worth protecting: the biological importance of Southeast Asia's repeatedly logged forests

Southeast Asia is a hotspot of imperiled biodiversity, owing to extensive logging and forest conversion to oil palm agriculture. The degraded forests that remain after multiple rounds of intensive logging are often assumed to be of little conservation value; consequently, there has been no concerted effort to prevent them from being converted to oil palm. However, no study has quantified the biodiversity of repeatedly logged forests. We compare the species richness and composition of birds and dung beetles within unlogged (primary), once-logged and twice-logged forests in Sabah, Borneo. Logging had little effect on the overall richness of birds. Dung beetle richness declined following once-logging but did not decline further after twice-logging. The species composition of bird and dung beetle communities was altered, particularly after the second logging rotation, but globally imperiled bird species (IUCN Red List) did not decline further after twice-logging. Remarkably, over 75 per cent of bird and dung beetle species found in unlogged forest persisted within twice-logged forest. Although twice-logged forests have less biological value than primary and once-logged forests, they clearly provide important habitat for numerous bird and dung beetle species. Preventing these degraded forests from being converted to oil palm should be a priority of policy-makers and conservationists.

From coprophagy to predation: a dung beetle that kills millipedes

The dung beetle subfamily Scarabaeinae is a cosmopolitan group of insects that feed primarily on dung. We describe the first case of an obligate predatory dung beetle and contrast its behaviour and morphology with those of its coprophagous sympatric congeners. Deltochilum valgum Burmeister killed and consumed millipedes in lowland rainforest in Peru. Ancestral ball-rolling behaviour shared by other canthonine species is abandoned, and the head, hind tibiae and pygidium of D. valgum are modified for novel functions during millipede predation. Millipedes were killed by disarticulation, often through decapitation, using the clypeus as a lever. Beetles killed millipedes much larger than themselves. In pitfall traps, D. valgum was attracted exclusively to millipedes, and preferred injured over uninjured millipedes. Morphological similarities placing D. valgum in the same subgenus with non-predatory dung-feeding species suggest a major and potentially rapid behavioural shift from coprophagy to predation. Ecological transitions enabling the exploitation of dramatically atypical niches, which may be more likely to occur when competition is intense, may help explain the evolution of novel ecological guilds and the diversification of exceptionally species-rich groups such as insects.

Understanding trait-dependent community disassembly: dung beetles, density functions, and forest fragmentation

Anthropogenic disturbances such as fragmentation are rapidly altering biodiversity, yet a lack of attention to species traits and abundance patterns has made the results of most studies difficult to generalize. We determined traits of extinction-prone species and present a novel strategy for classifying species according to their population-level response to a gradient of disturbance intensity. We examined the effects of forest fragmentation on dung beetle communities in an archipelago of 33 islands recently created by flooding in Venezuela. Species richness, density, and biomass all declined sharply with decreasing island area and increasing island isolation. Species richness was highly nested, indicating that local extinctions occurred nonrandomly. The most sensitive dung beetle species appeared to require at least 85 ha of forest, more than many large vertebrates. Extinction-prone species were either large-bodied, forest specialists, or uncommon. These explanatory variables were unrelated, suggesting at least 3 underlying causes of extirpation. Large species showed high wing loading (body mass/wing area) and a distinct flight strategy that may increase their area requirements. Although forest specificity made most species sensitive to fragmentation, a few persistent habitat generalists dispersed across the matrix. Density functions classified species into 4 response groups on the basis of their change in density with decreasing species richness. Sensitive and persistent species both declined with increasing fragmentation intensity, but persistent species occurred on more islands, which may be due to their higher baseline densities. Compensatory species increased in abundance following the initial loss of sensitive species, but rapidly declined with increasing fragmentation. Supertramp species (widespread habitat generalists) may be poor competitors but strong dispersers; their abundance peaked following the decline of the other 3 groups. Nevertheless, even the least sensitive species were extirpated or rare on the smallest and most isolated islands.

Safety and tolerability of grass pollen tablets in sublingual immunotherapy--a phase-1 study

BACKGROUND

A single-centre, randomized, double-blind, placebo-controlled study.

AIMS

To compare the safety and tolerability of four different sublingual immunotherapy (SLIT) regimes in grass pollen allergic rhinitis.

METHODS

Thirty subjects sensitized to grass pollen were enrolled and allocated to four groups. Sublingual immunotherapy was administered in tablets daily for 10 days. Groups 1 and 2 received incremental sublingual doses of 100, 200, 300, 400 and 500 IR, Group 1 daily and Group 2 increments every second day. Repeated constant dose regimens of 300 IR and 500 IR were administered in Groups 3 and 4 respectively. Safety assessments included adverse events (AE), vital signs, electrocardiogram (ECG) and clinical laboratory tests.

RESULTS

Sublingual immunotherapy 300 IR (Group 3) administered in a constant dose and incremental doses up to 500 IR (Groups 1 and 2) were generally well tolerated. The majority of AEs were mild to moderate, the most common being oral pruritus, throat irritation and swollen tongue. Severe local AEs (swelling of throat) were observed only for Group 4. No serious systemic AEs were reported. There were no relevant changes in clinical laboratory, vital signs and ECG data.

CONCLUSION

Adverse events were mostly local (sublingual), were not severe and resolved rapidly. Using a 5-day induction regimen high-dose treatment up to 500 IR could be administered without important side-effects, in contrast to initiating with a constant dose of 500 IR. The data indicate that a short dose increase phase may reduce the incidence of AEs when high-dose SLIT is administered.

Skin irritation and exposure to diisocyanates in orthopedic nurses working with soft casts

BACKGROUND

Diisocyanates are widely used in industry, for example at hospitals as a constituent of Scotch Cast soft casts (3M, Glostrup, Denmark). They are a cause of occupational asthma and have been described as causing cutaneous problems both as irritants and as sensitizers.

OBJECTIVE

The sensitizing potential of diisocyanates has previously only sporadically been described, predominantly in case reports. Therefore, we conducted this study to investigate eventual work-related skin sensitization to diisocyanates in a regularly exposed population.

METHODS

The nursing staff of an orthopaedic outpatient clinic, consisting of 10 persons, were interviewed and subjected to patch testing using 5 types of diisocyanates and the TRUE Test (ECDRG Standard Series) to elucidate possible other type IV allergies with similar symptoms. Patch test results were evaluated according to the guidelines of the International Contact Dermatitis Group.

RESULTS

We found no relationship between exposure time and severity of symptoms. Symptoms were mild, consisting of redness, itching, or both, lasting about 30 minutes. There was no suggestion that they result in any chronic skin problems. One nurse presented a doubtful reaction towards diaminophenylmethane (MDA) and isophorene diisocyanate (IPDI). Nine persons had no reactions to the 5 diisocyanates used in the patch test. Positive reactions were seen to nickel (4/10), thiomersal (2/10), and perfume mix (1/10).

CONCLUSION

Our observations suggest that diisocyanates are primarily irritants rather than sensitizers in the professional setting studied. The skin symptoms of irritation were all mild and temporary.

Cytoskeletal involvement during hypo-osmotic swelling and volume regulation in cultured chick cardiac myocytes

The membrane skeleton in spherical cardiac myocytes subjected to hypo-osmotic challenge was examined by laser scanning confocal microscopy. A distinct cortical layer intimately localized under the plasmalemma was revealed for spectrin and actin (including filamentous actin and alpha-sarcomeric actin). Desmin filaments were abundant and in close contact with the plasmalemma. During swelling and subsequent regulatory volume decrease (RVD) the structural integrity of these cytoskeletal elements remained intact, and the close association between actin and plasmalemma persisted as confirmed by double immunolabeling. Subplasmalemmal beta-tubulin labeling was sparse. Hypo-osmotic conditions disrupted the microtubules and depolymerized tubulin. Neither pretreatment with taxol nor with colchicine, resulted in any effect on cell volume regulation. The present results show that actin, desmin, and spectrin contribute to a subplasmalemmal cytoskeletal network in spherical cardiac myocytes, and that this membrane skeleton remains structurally intact during swelling and RVD. It is suggested that the integrity of this membrane skeleton is important for stabilization of the plasmalemma and the membrane-integrated proteins during hypo-osmotic challenge, and that it may participate in the regulation of the cell volume.

Membrane skeleton in cultured chick cardiac myocytes revealed by high resolution immunocytochemistry

Distribution of cytoskeletal proteins with emphasis on the membrane-cytoskeleton interface was examined in cultured cardiac myocytes. Using specific antibodies recognizing alpha-sarcomeric actin, desmin, beta-tubulin, spectrin/alpha-fodrin and ankyrin, respectively, the cellular localization of these cytoskeletal proteins was detected by laser scanning confocal microscopy. In addition, the fine filamentous structure of these proteins was identified by combining silver-enhanced immunogold labelling with electron microscopy. The latter technique employed the sequence of quick-freezing, deep-etching and rotary shadowing of the specimens. Conventional transmission electron microscopy of the spherical cardiac myocytes revealed a filamentous submembranous layer, approximately 100 nm thick. Specific immunolabelling of alpha-sarcomeric actin and spectrin/alpha-fodrin as well as ankyrin was seen beneath the plasmalemma. A three-dimensional meshwork of spectrin/alpha-fodrin was shown. Numerous desmin filaments that exhibited a tortuous course throughout the cells were also observed running in parallel with the surface in the submembranous area, whereas beta-tubulin was infrequently detected in these areas. In conclusion, the present study shows that spherical cardiac myocytes contain a distinct and complex three-dimensional membrane skeleton. Major constituents of this distinct submembranous layer were spectrin/alpha-fodrin fibres as well as actin and desmin filaments.

Translocation of 60S ribosomal subunit in spreading cardiac myocytes

Cardiac myocytes in culture undergo considerable structural reorganization. The remodeling of the myofibrils and the nonmyofibrillar cytoskeleton that occurs in the spreading cardiac myocytes resembles the cellular features observed in the hypertrophying heart. In this study we examined the distribution of the large 60S ribosomal subunit in freshly isolated cardiac myocytes and during the course of attachment and spreading in culture. Initially, anti-60S immunolabeling was scattered widely throughout the sarcoplasm of the dissociated cardiac myocytes. After attachment to the substrate, the 60S ribosomal subunit attained wide sarcoplasmic localization before a sarcomere-related staining pattern appeared in the spreading cell. Double labeling experiments with alpha-actinin confirmed co-localization of the 60S ribosomal subunit with nascent and mature myofibrils. These findings demonstrate that translocation of the 60S ribosomal subunit coincides with the cytoskeletal reorganization taking place in these cells. Moreover, the close association between the myofibrils indicates a particular role for the ribosomes in maintenance and growth of the contractile apparatus. (J Histochem Cytochem 46:963-969, 1998)

Regional activation of the immediate-early response gene c-fos in infarcted rat hearts

Regional infarction of the left ventricle is followed by hypertrophy of the viable myocardium. This compensatory growth of cardiac myocytes requires induction of gene transcription and synthesis of proteins. In this study, we examined the expression of the immediate-early response gene c-fos following ligation of the left coronary artery in rat hearts. RNase protection assay demonstrated a rapid increase in the c-fos mRNA level in the ventricular myocardium. After two days of infarction, the c-fos expression was attenuated and was comparable to that observed in sham-operated control hearts. In situ tissue distribution of Fos protein-like immunoreactivity revealed the appearance of positively stained cells adjacent to the lateral border of the ischaemic myocardium, in the left ventricular subendocardial areas, in the papillary muscles of the left ventricle, in the proximity of great transmural vessels, and focally in the normo-perfused subepicardial myocardium. Double staining using antibodies recognizing the Fos protein and alpha-actinin, confirmed that the accumulation of nuclear Fos protein-like immunoreactivity was mainly seen in the cardiac myocytes. However, double staining of the Fos protein and Hoechst DNA labelling showed that detectable immunoreactivity occurred only in a limited proportion of the total nuclei present in these myocardial regions. Moreover, the regions showing c-fos activation correspond to the areas in which the appearance of subsequent growth responses are most pronounced following myocardial infarction. The present results therefore indicate that an early and regional c-fos activation is taking place in viable cardiac myocytes following left coronary artery ligation, and that c-fos is a possible regulating factor of sequential events leading to altered pattern of gene expression and protein synthesis in the hypertrophying heart.

Effect of collagenase on surface expression of immunoreactive fibronectin and laminin in freshly isolated cardiac myocytes

The extracellular glycoproteins fibronectin (FN) and laminin (LMN) are ubiquitously expressed in myocardial tissue. These glycoproteins are important for cellular attachment and differentiation of the cardiac myocytes. Utilizing specific antibodies for the detection of FN and LMN, respectively, the distribution of these extracellular proteins was examined in enzymatically isolated adult cardiac myocytes. Immunofluorescence staining of rod-shaped cardiac myocytes revealed only remnants of immunoreactive FN on the cellular surface and in the transverse tubular membrane system. LMN expression, however, was preserved in a raster-like pattern in the cardiac myocytes. In order to study the distribution of these glycoproteins at high resolution, scanning electron microscopy using the backscattered electron mode was combined with immunogold staining and silver-enhancement. In addition, to confirm the immunofluorescence microscopic observations it was shown that FN labelling was restricted to ill-defined extracellular material and that LMN was absent from the intercalated discs of the cardiac myocytes. The hypercontracted cells were characterized by numerous surface protrusions devoid of immunoreactive LMN. Thus, these results indicate that FN and LMN are differently affected by collagenase treatment, and that these changes of glycoprotein expression may influence the normal function of the cardiac myocytes as well as the membrane stability during the development of irreversible cellular lesions.

F-actin modulates swelling-activated chloride current in cultured chick cardiac myocytes

The integrity of F-actin and its association with the activation of a Cl- current (I(Cl)) in cultured chick cardiac myocytes subjected to hyposmotic challenge were monitored by whole cell patch clamp and fluorescence confocal microscopy. Disruption of F-actin by 25 microM cytochalasin B augmented hyposmotic cell swelling by 51% (from a relative volume of 1.54 +/- 0.10 in control to 2.33 +/- 0.21), whereas stabilization of F-actin by 20 microM phalloidin attenuated swelling by 15% (relative volume of 1.31 +/- 0.05). Trace fluorochrome-labeled (fluorescein isothiocyanate or tetramethylrhodamine isothiocyanate) phalloidin revealed an intact F-actin conformation in control cells under hyposmotic conditions despite the considerable changes in cell volume. Sarcoplasmic F-actin was very disorganized and occurred only randomly beneath the sarcolemma in cells treated with cytochalasin B, whereas no changes in F-actin distribution occurred under either isosmotic or hyposmotic conditions in cells treated with phalloidin. Swelling-activated I(Cl) (68.0 +/- 6.0 pA/pF at +60 mV) was suppressed by both cytochalasin B (22.7 +/- 5.1 pA/pF) and phalloidin (22.5 +/- 3.5 pA/pF). On the basis of these results, we suggest that swelling of cardiac myocytes initiates dynamic changes in the cytoarchitecture of F-actin, which may be involved in the volume transduction processes associated with activation of I(Cl).

Human pheochromocytoma: different patterns of catecholamines and chromogranins in the intact tumour, urine and serum in clinically unsuspected cases

Clinically unsuspected pheochromocytoma is usually discovered either at autopsy or during surgical intervention for unrelated conditions, despite often enormous neoplastic masses producing and storing catecholamine (CA). In order to assess whether these tumours share some common features we have compiled data for six patients admitted to hospital without previous diagnosis of their pheochromocytoma. The clinical variables and the morphological and immunohistochemical characteristics of the tumours revealed that these cases represented quite different expressions of adrenomedullary neoplasms. They differed not only with respect to nuclear ploidity and overall cytoplasmic morphology but also in catecholamine storage and expression of immunoreactive chromogranin A sequences in the intact tissue. In two of the patients hypertension had been overlooked as a diagnostic indicator of their CA-producing tumours. There was no clear relationship between the mean arterial pressure, the tumour content of CA and the serum levels of CA. Processed chromogranin A dominated in the serum of the two hypertensive cases. The 24-h urine values of CA and its main metabolite (vanillin mandelic acid) were, together with the serum values of chromogranin A and B, proportional to tumour mass and provided the most reliable diagnostic indicators for the non-hypertensive as well as the hypertensive cases.

Pre- and post-embedding immunoelectron microscopy of Ki-M1P immunoreactive germinal center macrophages using ultra-small gold probes with silver enhancement

The Ki-M1P protein is primarily detected in cells deriving from the monocyte/macrophage cell lineage. The aim of this study was to investigate the occurrence of Ki-M1P immunoreactivity in germinal center macrophages by immunohistochemical and immunocytochemical staining techniques. Ultra-small (0.8 nm) gold probes combined with silver enhancement were used as a detection system for pre- and post-embedding immunostaining both at the light and electron microscopic level. Ki-M1P-positive macrophages were observed at a constant frequency in the germinal centers of the follicles throughout the tonsillar lymphatic tissue. The specific immunostaining was localized in the cytoplasm of these cells. Electron microscopic examination demonstrated the presence of abundant lysosomes in the cytoplasm, and some of the germinal center macrophages contained phagocytosed cells (tingible bodies) showing signs of various degrees of digestion. Ki-M1P immunoreactivity, as revealed by depositions of silver-enhanced ultra-small gold probes, was confined to the periphery of the lysosomes and tingible bodies. The results obtained demonstrate that the use of silver-enhanced ultra-small gold probes is a highly sensitive and specific detection system for pre- and post-embedding immunostaining of the Ki-M1P protein, and provides, in general, a flexible system for combined light and electron microscopic examination of tissue antigens. Furthermore, in the cytoplasm of the germinal center macrophages a spatial association between the Ki-M1P protein and lysosomes and tingible bodies was observed. These findings may indicate that the Ki-M1P protein is connected with phagocytosis and/or processes related to intracellular digestion in these cells.

Expression of fibronectin, laminin and ribosomes in normal and nocodazole-treated neonatal heart cells in culture: a study by laser scanning confocal microscopy and immunocytochemistry

Polyclonal and monoclonal antibodies were used to examine the effects of the synthetic microtubule disruptive drug nocodazole on the subcellular expression of fibronectin, laminin, and ribosomes in primary cultures of neonatal cardiac ventricular cells. Non-invasive serial optical sectioning was carried out by immunolaser scanning confocal microscopy. In addition, fibronectin and laminin were immunolabelled with peroxidase or gold conjugates for electron-microscopic examination. Immunolabelling for the large 60S ribosome subunit in fibroblast-like non-myocytes showed that punctate ribosome structures with a multi-subunit composition were present in perinuclear region. Double immunostaining with antibodies directed against ribosomes and cellular fibronectin indicated that the punctate structures were cisternae of the rough endoplasmic reticulum. No clear effects of nocodazole treatment were detected on the distribution of cytoskeleton-bound ribosomes. Following immunolabelling for both glycoproteins and double immunolabelling for cellular fibronectin and the 60S ribosome subunit, fibronectin and laminin were found in the perinuclear cisternae of the rough endoplasmic reticulum and in pleomorphic secretory vesicles. The cisternal stacks of the Golgi complex appeared either unstained or were only weakly labelled. When these cells were exposed to nocodazole, fibronectin and laminin accumulated in peripheral parts of the cytoplasm, including cellular processes. These peripheral accumulation of immunostaining for fibronectin and laminin did not reflect Golgi staining, as shown by double labelling experiments versus wheat-germ-agglutinin staining, and, by exposing cultures to a high dose of brefeldin A.

Fibronectin penetration into heart myocytes subjected to experimental ischemia by coronary artery ligation

Using confocal microscopy and immunocytochemistry we have studied early changes in distribution of fibronectin (FN) in myocardial cells of rats subjected to experimental acute myocardial ischemia (AMI) by coronary ligation for several periods of 0.5 h to 6 days. In sham-operated and nonoperated rats, FN was present in the interstitium around the myocytes, and in their transverse tubules (TT). Already after 0.5 h of ischemia there was a well-defined increase of immunoreactive FN in focal areas of the interstitium of the hypoperfused portion, and distinct penetration into adjacent myocytes. The early penetration of FN into myocytes appears to follow a path through the TT, with a codistribution with actin in the I bands. This process precedes a total and diffuse infiltration of FN into the cytoplasm of disintegrating myocytes at later stages of coronary occlusion.

[The contractile heart. Cellular and subcellular aspects]

The excitation-contraction coupling can be defined as the mechanisms involved when the action potential initiates a contraction response of the cardiac muscle cell. The action potential is conducted from cell to cell, resulting in a synchronized contraction of the myocardium. Both the propagation of the action potential and the myofibrillar contraction are dependent on changes in free Ca++ concentrations. Recently, the mediators and the molecular and structural components involved in the subcellular transforming of the action potential into a contraction have been characterized. The opening of voltage-dependent L-type Ca(++)-channels in the cell membrane stimulates a release of Ca++ from the sarcoplasmic reticulum. This Ca(++)-mediated Ca(++)-release appears to be a graded mechanism and is associated with the presence of structural couplings (Ca++ synapses) in the cardiac muscle cell.

Regulation of c-fos expression by IGF-I in bovine chromaffin cells: desensitization following cholinergic activation

Effects of insulin-like growth factor I on the expression of the immediate-early gene c-fos in adrenomedullary tissue were assessed in bovine chromaffin cells in primary culture. The expression of c-fos mRNA and FOS protein were studied by Northern blot and immunofluorescence microscopy. IGF-I induced c-fos mRNA expression in a dose-dependent manner, reaching a maximum at 10-100 nM after 30 min incubation. Expression of FOS protein exhibited a transient time course peaking after 60-90 min. Repeated exposures to IGF-I attenuated c-fos transcriptional activity with a temporal coincidence of 90% repression and maximal FOS protein levels. Exposure to the cholinergic agonist carbachol or the protein tyrosine phosphatase inhibitor orthovandate also induced c-fos transcription. Both agents caused repression in c-fos gene activation induced by either IGF-I, carbachol or orthovanadate. This suggested autoinhibition of c-fos transcription by FOS protein synthesized during the initial stimulation period. These data are consistent with IGF-I stimulating c-fos gene activation in the adrenal medulla and show that c-fos expression can be negatively regulated by temporal neural and hormonal stimulation.

Immunoreactive atrial natriuretic peptide and dopamine beta-hydroxylase in myocytes and chromaffin cells of the heart of the African lungfish, Protopterus aethiopicus

The heart of the African lungfish, Protopterus aethiopicus, was examined for immunoreactive atrial natriuretic peptide (ANP) and dopamine beta-hydroxylase (D beta H) as markers for hormone secreting myocytes and chromaffin cells, respectively. Specific antibodies raised against rat alpha-ANP and rat D beta H were used for immunofluorescence microscopy and immunogold electron microscopy. D beta H-immunoreactive cells were restricted to subendocardial areas of the atrium whereas ANP immunoreactivity occurred throughout both the atrial and the ventricular myocardium, showing particularly strong staining intensity in the atrial myocytes. The granular ANP immunostaining in the atrial myocytes was frequently accumulated in the sarcoplasm. In the ventricular myocytes ANP immunoreactivity occurred as scattered granular staining throughout the sarcoplasm. ANP and D beta H immunofluorescence staining coincided with the presence of immunoreactive specific granules and secretory vesicles in the cardiac myocytes and chromaffin cells, respectively, as revealed by electron microscopy. The number of ANP-containing specific granules was generally high in the atrial myocytes, and they were frequently observed in clusters in subsarcolemmal areas. Granular frequency was considerably lower and the mean granular diameter was smaller (0.142 +/- 0.045 micron versus 0.213 +/- 0.049 micron) in the ventricular than in the atrial myocytes. The present results indicate that ANP and D beta H are phylogenetically highly conserved proteins from the dipnoi to the rat. The large amounts of ANP and of specific granules are consistent with an endocrine myocardium in the Protopterus heart. The presence of D beta H and secretory vesicles in the subendocardial chromaffin cells of the atrium suggests a local production of catecholamines from dopamine in the heart of this dipnoan.

Ribosome distribution in normal and infarcted rat hearts

Distribution of ribosomes throughout the myocardium of normal and infarcted rat hearts was studied by immunofluorescence and laser confocal scanning microscopy. In addition, sections were labelled with peroxidase or immunogold particles for electron microscopic examination. Ligation of the proximal free left coronary artery produced severe myocardial ischaemia, and after 6 days of ligation most of the left ventricular wall was necrotic and partially replaced by granulation tissue. Immunofluorescence microscopy revealed the presence of ribosomes throughout the non-necrotic myocardium. Some cardiac muscle cells located in subendocardial areas and in the border areas surrounding the infarct were particularly intensely stained. Cells constituting the granulation tissue frequently exhibited strong ribosomal immunostaining. Within longitudinally sectioned cardiac muscle cells, ribosomes were organized in strands oriented along the long axis of the cell as well as in a cross-striated pattern. By double labelling of muscle cells with antibodies against ribosomes and Z-line-associated proteins (desmin or alpha-actinin), it was shown that the cross-striated bands of anti-ribosomal staining coincided with the I-bands along the myofibrils. Immunoelectron microscopy confirmed a wide distribution of ribosomes throughout the intermyofibrillar and subsarcolemmal sarcoplasm, and some labelling was also observed within the I-band. The present results indicate that ribosomes are distributed in a characteristic pattern throughout the sarcoplasm of cardiac muscle cells in association with the myofibrils. Furthermore, it is suggested that within viable cardiac muscle cells located adjacent to the infarct, protein synthesis is increased; this might be an important factor in regional development of compensatory hypertrophy of the surviving cardiac muscle cells.

Regional appearance of atrial natriuretic peptide in the ventricles of infarcted rat hearts

The appearance of atrial natriuretic peptide (ANP) in the ventricular myocardium was investigated in rat hearts subjected to severe left ventricular infarction. The left coronary artery was ligated for 1, 2, 3, 4 and 6 days and for 3 weeks, and the tissue was prepared for microscopic examination of immunoreactive ANP and for electron microscopy. In the normal and sham-operated hearts, and in hearts subjected to 1 day of coronary ligation, ANP immunoreactivity was restricted to a few ventricular myocytes of the conduction system. Following 2-3 days of coronary ligation, ANP immunoreactivity was detected in the viable myocardium of the lateral border of the infarct and in a few layers of viable cardiac myocytes located in the subendocardial areas of the ischemic left free ventricular wall. Further, during the following days and after 3 weeks of coronary ligation, a gradient of specific labeling was commonly seen across the lateral border area of the infarct. Thus, the strongest immunoreactivities were present in the cardiac myocytes located adjacent to the non-contracting myocardium. Electron microscopic examination of the immunoreactive cardiac myocytes confirmed the presence of electron-dense specific granules within these cells. The present findings suggest that the increased regional production of ANP within the ventricular myocardium is induced by increased mechanical stretch of the cardiac myocytes, and that this might contribute to the increased release of ANP in myocardial infarction.

Inhibition and down-regulation of protein kinase C in cultured atrial myocytes: effects on distribution of specific granules and secretion of atrial natriuretic peptide

Primary cultures of neonatal rat atrial myocytes were subjected to down-regulation of protein kinase C (PKC) and to inhibition of PKC activity. The effects on secretion of atrial natriuretic peptide (ANP), and the intracellular distribution of ANP-containing specific granules and their association to microtubules, were investigated. Treating the cultures with inhibitors of PKC, staurosporine or H7, a translocation of ANP-containing specific granules from the perinuclear sarcoplasm to the periphery of the myocytes was observed, and furthermore, secretion of ANP was significantly decreased. The microtubule network were not structurally affected by the PKC inhibitors. Down-regulation of PKC by 12-O-tetradecanoylphorbol 13-acetate (TPA) for 12 h was not followed by any alteration of localization of specific granules, and the amount of secreted ANP was still considerable. Treating the down-regulated cultures with staurosporine, secretion of ANP was still significantly reduced. The present results suggest that the decreased ANP secretion and the translocation of ANP-containing specific granules in the atrial myocytes following treatment with staurosporine or H7, is mediated through mechanisms not, or only partly, requiring PKC.

Microtubule-associated distribution of specific granules and secretion of atrial natriuretic factor in primary cultures of rat cardiomyocytes

A close spatial relationship between specific granules containing atrial natriuretic factor (ANF) and microtubules was demonstrated in primary cultures of neonatal rat cardiac myocytes. For the detection of specific granules and microtubules, the myocytes were double immunolabeled with antibodies against alpha-ANF and beta-tubulin and examined by conventional fluorescence or laser scanning confocal microscopy. In addition, the ultrastructural distribution of specific granules was demonstrated by electron microscopy. In the atrial myocytes, ANF was stored in numerous specific granules that were mainly localized in the perinuclear sarcoplasm. In the ventricular myocytes, however, a minority of the cells (10%) exhibited limited ANF immunoreactivity after 4 days in culture. Microtubules were present throughout the sarcoplasm of the myocytes. They were most densely packed in the perinuclear regions. Depolymerization of the microtubules with nocodazole was followed by dispersal of ANF immunostaining both in the atrial myocytes and in the ventricular myocytes exhibiting ANF immunoreactivity. When the microtubules were allowed to recover, the perinuclear distribution of specific granules, as seen in non-treated myocytes, reappeared. Measurements of secreted immunoreactive ANF by radioimmunoassay revealed that the secretion of ANF from atrial myocytes into the medium was significantly reduced following nocodazole treatment, whereas a similar decrease in secretion from ventricular myocytes was not observed. These findings indicate that ANF-containing specific granules are closely associated with microtubules within the myocytes. It is suggested that secretion of ANF from the atrial myocytes, in contrast to the ventricular myocytes, is microtubule-dependent.

Atrial natriuretic factor in cats subjected to acute myocardial ischaemia

Eighteen anaesthetized open chest cats were subjected to 10, 30, or 50 min occlusion of the left anterior descending coronary artery (LAD). Heart rate, left ventricular end-diastolic (LVEDP) and systolic pressure (LVSP), and dp/dt were continuously recorded during the experiments. Prior to LAD-occlusion, and just before termination of the experiments, blood samples were collected from the left femoral artery for measurements of atrial natriuretic factor (ANF), catecholamines, electrolytes, urea, and creatinine. Simultaneously, biopsies were collected from the right auricular wall. The tissue was embedded in Lowicryl K4M, and ultrathin sections were incubated with anti-ANF antibodies and secondary antibodies conjugated to gold particles. The density of ANF-containing atrial-specific granules labelled with gold particles was morphometrically calculated. LVEDP increased significantly in all three time groups, and when pooling the pre- and postocclusion values, there was an increase from 5.1 +/- 0.4 to 10.3 +/- 1.2 mmHg (p < 0.05). The noradrenaline level increased from 0.93 +/- 0.18 to 2.34 +/- 0.75 nmol l-1 (p < 0.05) after LAD-occlusion. Similarly, the mean plasma level of ANF in the 18 cats increased from 57.6 +/- 11.9 to 98.9 +/- 22.6 pmol l-1 (p < 0.05). Atrial granular density appeared to decline after 10 min of occlusion (from 0.141 +/- 0.017 to 0.127 +/- 0.022 granules-1 microns 2 sarcoplasm), and after 30 min there was a significant decrease (0.080 +/- 0.012 granules/microns 2, p < 0.05). However, after 50 min occlusion the granular density was almost restored (0.133 +/- 0.017 granules/microns 2). Plasma ANF showed a positive linear correlation to LVEDP and to the noradrenaline level.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial natriuretic factor in the heart of the human embryo

The presence of atrial natriuretic factor (ANF) has been demonstrated in striated myocytes of the human embryonic heart as well as in the adult heart, by immunohistochemical and immunocytochemical methods. The postconceptional age of the embryos ranged from 8 to 9 weeks. At this early stage of development, shortly after the appearance of atrial granules in humans, ANF was localized both in the auricles and remaining parts of both atria. Immunostaining was intensified in the subendocardial areas. No immunoreactivity was observed in the developing ventricles. Immunogold electron microscopy of atrial myocytes showed that the ANF-containing atrial granules were distributed throughout the sarcoplasm, although they tended to accumulate in the paranuclear areas. Neither the Golgi apparatus nor the rough endoplasmic reticulum exhibited ANF immunoreactivity, indicating that immunoreactive ANF of the human embryonic atria is stored in the mature granules. These results indicate an endocrine function of the human embryonic atria.

Immunocytochemical localization of atrial natriuretic peptide in the venae cavae and the pulmonary veins of the rat

In the present investigation 'atrial natriuretic peptide' (ANP) was localized in striated myocytes of the venae cavae and the pulmonary veins in the rat by the use of immunohistochemical and immunocytochemical staining techniques. ANP was stored in granules which appeared to be morphologically similar to the 'atrial specific granules' (ASG) of the atria. In general, the amount of ASG in the great thoracic veins was less than observed in the atria, and the specific granules appeared to be more evenly distributed throughout the sarcoplasm. However, the presence of ANP-containing specific granules in the venae cavae and the pulmonary veins may suggest participation of these veins in the production and secretion of the hormone.

Striated myocytes and atrial specific granules in the pulmonary veins of chronically infarcted rat hearts

The ultrastructure of the striated myocytes in the pulmonary myocardium of the Wistar rat, was studied following left ventricular infarction (LVI) for 4 days and 4 weeks, respectively. Ischemia was provided by ligating of the left coronary artery which successively produces left ventricular dysfunction and congestion of the left atrium and pulmonary veins. In general, the striated myocytes of the extrapulmonary veins of the control groups displayed ultrastructural characteristics similar to those of the left atrium. However, in the former, transverse tubules commonly occurred making interior couplings with the SR at the I-band levels. Also, between striated myocytes of the intrapulmonary veins of the controls nexus-like junctions of about 2 micron length were observed. Further, in the same groups atrial specific granules (ASG), including A-granules and B-granules, were present in about 20%-30% of the striated myocytes of the extrapulmonary veins as shown in single sections. The ASG tended to decrease by number in areas approaching the lung hilus and were not observed in the intrapulmonary veins of the controls. After 4 days of ventricular ischemia granules also appeared in the intrapulmonary veins. They were mostly seen in single and randomly spread in the cytoplasm of a limited number of cells, i.e., in between 0% and 5% of the myocytes as seen in single sections. Four days of LVI produced only minor cellular injuries to the extrapulmonary and intrapulmonary venous wall, while more severe lesions appeared in both areas following 4 weeks of LVI. Such lesions were preferably localized to the adluminal surface and consisted mainly of Z-band and sarcomere anomalies, vacuolization of the cytoplasm and mitochondrial swelling.

The ultrastructure of the myocyte in different regions of experimental infarcts in the cat heart

The ultrastructure of myocytes was studied in the left ventricular myocardium of the cat heart after 3 h of LAD ligation. The ischemic, borderline, and normally perfused myocardium was defined by in vivo injection of fluorescein and by regional myocardial blood flow measurements with 15.5 microns radio-labeled microspheres. A semiquantitation of the number of irreversible injured cells in per cent of total counted in the three different zones showed that 53%-63% were irreversibly injured in the ischemic zone, 7%-26% in the borderline area, while none were irreversibly injured in the normally perfused myocardium. The interior excitation-contraction couplings in the normally perfused myocardium comprise interior dyads, triads, reversed triads, and encircling couplings. While the couplings in general were structurally resistant to ischemia, injured interior couplings were apparent in severely damaged cells of the hypoperfused tissue. Such injuries comprise a widening of the junctional gap and a disintegration of the junctional processes.