Diabetes mellitus: a primary metabolic disturbance. Metabolomics underlying vascular responses to stress and ischemia?

Diabetes mellitus (DM) is a primary metabolic disorder and the impact of this entity on maladaptive tissue and organ responses may be mediated through alter metabolomic profile and signatures at steady state or at stress. To this point of view Beckman et al. (Clin. Sci. (Lond.) (2020) 134, 2369–2379), in a hypothesis-generated study, investigated how metabolomic profile is affected following branchial artery ischemia. Interestingly, they found that there is a dynamic and altered change of metabolites associated with energy substrate and with glycolysis/glyconeogenesis in patients with DM. This evidence may shed light on the impaired muscle tolerance in subjects with DM and on impaired vasoreactivity. However, these data lack the ability to be conclusive and further steps should be explored to understand how metabolomic profile is implicated in the response of muscle tissue to ischemia and to the clinical profile of subjects with DM.

Cross section of gill filaments in histological preparations helps better identification of the location of myxosporean plasmodia in gill tissues

Location and tissue preference of filamental-type myxosporean plasmodia in histological slides of the gills can be properly identified only in cross sections of the gill filaments. The authors selected three myxosporeans (Myxobolus rutili, M. dispar and Henneguya psorospermica, parasites of the roach, the common carp and the pike, respectively) for studying the problem. The plasmodia of these species studied in longitudinal sections were earlier regarded as developing inside the filamental arteries. Cross sections of the filaments showed that all the three species developed plasmodia in the dense connective tissue constituting the adventitia of gill arteries and covering the cartilaginous gill rays. Myxobolus rutili started its development close to the afferent branchial artery but attached to the cartilaginous gill ray. More developed plasmodia of this species surrounded the rays. Plasmodia of M. dispar were formed on the inner side of the afferent branchial artery, while those of H. psorospermica were located at the external side of the efferent branchial artery.

Study on respiratory organ of Schistura rupicola McClelland from Lamphengwa Khola, Gajurmukhi VDC, Ilam, Nepal

Gill structure of Schistura rupicola McClelland collected from Lamphengwa Khola, Gajurmukhi Village Developmemt Committee, Ilam, Nepal was studied by double staining in haematoxylin and eosin, and taking photomicrographs by digital camera and light microscope. Gill-rakers are present on both sides of gill-head. The gill bar is "V" shaped. The efferent branchial artery is larger than afferent branchial artery. The inter-branchial septum is 20.16% of holo-branch. The first gill-arch filaments of the mid region of the posterior hemi-branches are longer. In other gill-arches, the lengths of the posterior hemi-branches are greater than their counterparts on the anterior hemi-branch.

Acetylcholine produces contraction mediated by cyclooxigenase pathway in arterial vessels in the marine fish (Isacia conceptionis)

Preliminary studies showed that dorsal artery contraction mediated by acetylcholine (ACh) is blocked with indomethacin in intertidal fish (G. laevifrons). Our objective was to characterize the cholinergic pathway in several artery vessels of the I. conceptionis. Afferent and efferent branchial, dorsal and mesenteric arteries were dissected of 6 juvenile specimens, isometric tension studies were done using doses response curves (DRC) for Ach (10–13 to 10–3 M), and cholinergic pathways were obtained by blocking with atropine or indomethacin. CRC to ACh showed a pattern of high sensitivity only in efferente branchial artery and low sensibility in all vessels. Furthermore, these contractions were blocked in the presence of atropine and indomethacin in all vessels. Our results corroborate previous results observed in intertidal species that contraction induced by acetylcholine is mediated by receptors that activate a cyclooxygenase contraction pathway.

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The trichomycterid catfishes known as candirus are renowned for their blood feeding, but information on their habits under natural conditions is very fragmentary and generally restricted to hosts or habitats. We recorded an undescribed species of the vandelliine genus Paracanthopoma riding the giant jau catfish, Zungaro zungaro (Pimelodidae), in the upper Amazon. The candirus were found on the host's caudal and pectoral fins, as well as the base of the dorsal fin, with their snouts buried up to the eyes in the tough skin of the catfish host. All of them had small amounts of partly digested blood in the distal part of the gut. Along the host's dorsal fin base we found a few additional tiny holes, most of them healed. We suggest that Paracanthopoma feeds on the gill chamber of its hosts, and that the individuals we found were taking a ride partly buried into the host's skin. Our assumption seems supported by the widespread behaviour of vandelliine candirus taking blood from the gill region of their hosts, and by a report of Paracanthopoma parva found on the gills of another species of giant catfish, Brachyplatystoma vaillanti. Additionally, the Paracanthopoma sp. individuals we examined were not gorged with blood as usual for several vandelliines. Species within the genus Paracanthopoma have the longest and most robust snout, and the longest and strongest dentary teeth among blood-feeding candirus, which fit their drilling needs. Taking a ride on a giant host would be advantageous for Paracanthopoma candirus for several reasons: 1) dispersal; 2) no need to search for hosts to feed; and 3) protection from predators. The alternative explanation that Paracanthopoma takes blood from the tiny holes it drills in the skin seems unlikely, due to the recent finding that species of the genus Vandellia are unable to take blood from their hosts actively and cut open a major branchial artery to gorge themselves with blood due to the host's arterial pressure instead. The body parts of the host the Paracanthopoma sp. individuals were attached on have no large vessels that would supply them with plenty of blood. Thus, drilling a hole on a giant host skin seems to serve mostly to anchor the Paracanthopoma candirus to their long-distance cruising catfish host. If our assumption holds true, then species of this genus exemplify an instance of phoresis (hitch-hiking) among the blood-feeding candirus.