Decreased lymphatic vessel counts in patients with systemic sclerosis: Association with fingertip ulcers

Objective

Systemic sclerosis (SSc) is a connective tissue disease that is characterized by microvascular disease and tissue fibrosis. Progressive loss and irregular architecture of the small blood vessels are well characterized, but the potential involvement of the lymphatic vessel system has not been analyzed directly in SSc. This study was undertaken to assess whether the lymphatic vascular system is affected in SSc, and whether changes to the lymphatic vessels are associated with dystrophic changes and tissue damage in patients with SSc.

Methods

Lymphatic endothelial cells in skin biopsy samples from patients with SSc and age‐ and sex‐matched healthy volunteers were identified by staining for podoplanin and prox‐1, both of which are specifically expressed in lymphatic endothelial cells but not in blood vascular endothelial cells. CD31 was used as a pan–endothelial cell marker. Statistical analyses were performed using Kruskal‐Wallis, Mann‐Whitney U, and Spearman's rank correlation tests.

Results

The numbers of podoplanin‐ and prox‐1–positive lymphatic vessels were significantly reduced in patients with SSc as compared with healthy individuals. The number of podoplanin‐positive lymphatic precollector vessels was significantly lower in SSc patients with fingertip ulcers than in SSc patients without ulcers. Moreover, the number of lymphatic vessels correlated inversely with the number of fingertip ulcers at the time of biopsy and with the number of fingertip ulcers per year. The inverse correlation between lymphatic precollector vessel counts and fingertip ulcers remained significant after statistical adjustment for the blood vessel count, age, and modified Rodnan skin thickness score.

Conclusion

These results demonstrate a severe reduction in the number of lymphatic capillaries and lymphatic precollector vessels in patients with SSc. Patients with decreased lymphatic vessel counts may be at particularly high risk of developing fingertip ulcers.

     

Selective desensitization of the 5-HT4 receptor-mediated response in pig atrium but not in stomach

Background and purpose:

The time dependency of the effect of 5-HT₄ receptor agonists depends on many specific regulatory mechanisms, which vary between tissues. This has important implications with regard to the effects of endogenous 5-HT, as well as to the clinical use of 5-HT₄ receptor agonists, and might contribute to tissue selectivity of agonists.

Experimental approach:

The progression and desensitization of 5-HT₄ receptor-mediated responses were evaluated in an organ bath set-up using two, clinically relevant, porcine in vitro models: gastric cholinergic neurotransmission and atrial contractility.

Key results:

Exposure of gastric tissue to 5-HT or to the selective 5-HT₄ receptor agonists prucalopride and M0003 results in a sustained non-transient effect during exposure; after washout, the response to a subsequent challenge with 5-HT shows no clear desensitization. Incubation of left atrial tissue with 5-HT resulted in a transient response, leading after washout to a marked desensitization of the subsequent response to 5-HT. The selective 5-HT₄ receptor agonists prucalopride and M0003 induce only very weak atrial responses whereas they are very effective in desensitizing the atrial response to 5-HT. The observations also suggest that the properties of prucalopride and M0003 to bind to and/or activate the 5-HT₄ receptor differ from those of 5-HT. This difference might have contributed to the observed desensitization.

Conclusions and implications:

The high potency of prucalopride and M0003 in desensitizing the response to 5-HT together with their low efficacy in the atrium emphasizes the cardiac safety of this class of 5-HT₄ receptor agonists.     

Kisspeptin-54 at high doses acutely induces testicular degeneration in adult male rats via central mechanisms

Background and purpose:

The kisspeptins are critical regulators of reproduction and a therapeutic target for reproductive disease. Intracerebroventricular (i.c.v.) or peripheral injection of kisspeptin potently stimulates the hypothalamic-pituitary gonadal (HPG) axis via gonadotrophin-releasing hormone (GnRH). However, little is known regarding the effects of kisspeptin administration on testicular function. We investigated the mechanism(s) of kisspeptin-induced testicular degeneration in the rat.

Experimental approach:

Kisspeptin-54 (50 nmol·day⁻¹) was continuously administered subcutaneously (6 h to 3 days) to male Wistar rats and reproductive hormones and testicular histology analysed. We also investigated the effects of a single subcutaneous injection of 0.5, 5 or 50 nmol kisspeptin-54. In order to determine whether the testicular degeneration observed is peripherally or centrally mediated, we investigated effects of i.c.v. injections of 5 nmol kisspeptin-54 and pre-administered a GnRH-receptor antagonist (cetrorelix) to rats peripherally treated with kisspeptin-54.

Key results:

Continuous subcutaneous administration of kisspeptin-54 caused testicular degeneration after only 12 h, when gonadotrophins were still markedly raised, suggesting that the degeneration is independent of the desensitization of the HPG axis to kisspeptin-54. Furthermore, a single subcutaneous injection of kisspeptin-54 caused dose-dependent testicular degeneration. Continuous kisspeptin-54 administration is thus not required to cause testicular degeneration. Pretreatment with cetrorelix blocked kisspeptin-induced testicular degeneration, and a single i.c.v. injection of kisspeptin-54 caused testicular degeneration, suggesting it is GnRH-mediated.

Conclusions and implications:

Kisspeptin-induced testicular degeneration appears to be centrally mediated, and result from acute hyper-stimulation of the HPG axis. Doses must be carefully considered if kisspeptin is to be used therapeutically.     

Family circumstance, sedentary behaviour and physical activity in adolescents living in England: Project STIL

Background  

Identification of non-modifiable correlates of physical activity and sedentary behaviour in youth contributes to the development of effective targeted intervention strategies. The purpose of this research was to examine the relationships between family circumstances (e.g. socio-economic status, single vs. dual parent household, presence/absence of siblings) and leisure-time physical activity and sedentary behaviours in adolescents.     

Investigation of the distribution and function of ��-adrenoceptors in the sheep isolated internal anal sphincter

BACKGROUND AND PURPOSE

We have investigated the distribution of α-adrenoceptors in sheep internal anal sphincter (IAS), as a model for the human tissue, and evaluated various imidazoline derivatives for potential treatment of faecal incontinence.

EXPERIMENTAL APPROACH

Saturation and competition binding with ³H-prazosin and ³H-RX821002 were used to confirm the presence and density of α-adrenoceptors in sheep IAS, and the affinity of imidazoline compounds at these receptors. A combination of in vitro receptor autoradiography and immunohistochemistry was used to investigate the regional distribution of binding sites. Contractile activity of imidazoline-based compounds on sheep IAS was assessed by isometric tension recording.

KEY RESULTS

Saturation binding confirmed the presence of both α₁- and α₂-adrenoceptors, and subsequent characterization with sub-type-selective agents, identified them as α_1A- and α_2D-adrenoceptor sub-types. Autoradiographic studies with ³H-prazosin showed a positive association of α₁-adrenoceptors with immunohistochemically identified smooth muscle fibres. Anti-α₁-adrenoceptor immunohistochemistry revealed similar distributions of the receptor in sheep and human IAS. The imidazoline compounds caused concentration-dependent contractions of the anal sphincter, but the maximum responses were less than those elicited by l-erythro-methoxamine, a standard non-imidazoline α₁-adrenoceptor agonist. Prazosin (selective α₁-adrenoceptor antagonist) significantly reduced the magnitude of contraction to l-erythro-methoxamine at the highest concentration used. Both prazosin and RX811059 (a selective α₂-adrenoceptor antagonist) reduced the potency (pEC₅₀) of clonidine.

CONCLUSIONS AND IMPLICATIONS

This study shows that both α₁- and α₂-adrenoceptors are expressed in the sheep IAS, and contribute (perhaps synergistically) to contractions elicited by various imidazoline derivatives. These agents may prove useful in the treatment of faecal incontinence.     

Inhibition of angiotensin-converting enzyme stimulates fracture healing and periosteal callus formation – role of a local renin-angiotensin system

Background and purpose:

The renin-angiotensin system (RAS) regulates blood pressure and electrolyte homeostasis. In addition, ‘local’ tissue-specific RAS have been identified, regulating regeneration, cell growth, apoptosis, inflammation and angiogenesis. Although components of the RAS are expressed in osteoblasts and osteoclasts, a local RAS in bone has not yet been described and there is no information on whether the RAS is involved in fracture healing. Therefore, we studied the expression and function of the key RAS component, angiotensin-converting enzyme (ACE), during fracture healing.

Experimental approach:

In a murine femur fracture model, animals were treated with the ACE inhibitor perindopril or vehicle only. Fracture healing was analysed after 2, 5 and 10 weeks using X-ray, micro-CT, histomorphometry, immunohistochemistry, Western blotting and biomechanical testing.

Key results:

ACE was expressed in osteoblasts and hypertrophic chondrocytes in the periosteal callus during fracture healing, accompanied by expression of the angiotensin type-1 and type-2 receptors. Perindopril treatment reduced blood pressure and bone mineral density in unfractured femora. However, it improved periosteal callus formation, bone bridging of the fracture gap and torsional stiffness. ACE inhibition did not affect cell proliferation, but reduced apoptotic cell death. After 10 week treatment, a smaller callus diameter and bone volume after perindopril treatment indicated an advanced stage of bone remodelling.

Conclusions:

Our study provides evidence for a local RAS in bone that influenced the process of fracture healing. We show for the first time that inhibition of ACE is capable of accelerating bone healing and remodelling.     

Letter to the editor: Diagnosis of erythropoietic protoporphyria with severe liver injury-a case report

Erythropoietic protoporphyria(EPP)is an extremely rare disease which is often unrecognized as diagnosis.In the recent article Lui et al describe a patient with a new diagnosis of EPP with severe liver injury.Approximately 5%-20%of patients with EPP develop liver manifestations.The most severe complication of EPP is an hepatic crisis,which is a medical emergency requiring urgent treatment.Intensive treatment should consist of(exchange)transfusions and preferably in a center that performs liver transplantations.     

Genetic and functional association of FAM5C with myocardial infarction

Background

We previously identified a 40 Mb region of linkage on chromosome 1q in our early onset coronary artery disease (CAD) genome-wide linkage scan (GENECARD) with modest evidence for linkage (n = 420, LOD 0.95). When the data are stratified by acute coronary syndrome (ACS), this modest maximum in the overall group became a well-defined LOD peak (maximum LOD of 2.17, D1S1589/D1S518). This peak overlaps a recently identified inflammatory biomarker (MCP-1) linkage region from the Framingham Heart Study (maximum LOD of 4.27, D1S1589) and a region of linkage to metabolic syndrome from the IRAS study (maximum LOD of 2.59, D1S1589/D1S518). The overlap of genetic screens in independent data sets provides evidence for the existence of a gene or genes for CAD in this region.

Methods

A peak-wide association screen (457 SNPs) was conducted of a region 1 LOD score down from the peak marker (168–198 Mb) in a linkage peak for acute coronary syndrome (ACS) on chromosome 1, within a family-based early onset coronary artery disease (CAD) sample (GENECARD).

Results

Polymorphisms were identified within the 'family with sequence similarity 5, member C' gene (FAM5C) that show genetic linkage to and are associated with myocardial infarction (MI) in GENECARD. The association was confirmed in an independent CAD case-control sample (CATHGEN) and strong association with MI was identified with single nucleotide polymorphisms (SNPs) in the 3' end of FAM5C. FAM5C genotypes were also correlated with expression of the gene in human aorta. Expression levels of FAM5C decreased with increasing passage of proliferating aortic smooth muscle cells (SMC) suggesting a role for this molecule in smooth muscle cell proliferation and senescence.

Conclusion

These data implicate FAM5C alleles in the risk of myocardial infarction and suggest further functional studies of FAM5C are required to identify the gene's contribution to atherosclerosis.