Ion uptake in naturally acidic water.

The first studies on ion regulation in fish exposed to low pH, which were inspired by the Acid Rain environmental crisis, seemed to indicate that ion transport at the gills was completely and irreversibly inhibited at pH 4.0-4.5 and below. However, work on characid fish native to the Rio Negro, a naturally acidic, blackwater tributary of the Amazon River, found that they possess ion transport mechanisms that are completely insensitive to pHs as low as 3.25. As more species were examined it appeared that pH-insensitive transport was a trait shared by many, if not most, species in the Order Characiformes. Subsequently, a few other species of fish have been shown to be able to transport ions at low pH, in particular zebrafish (Danio rerio), which show rapid recovery of Na+ uptake at pH 4.0 after initial inhibition. Measurements of rates of Na+ transport during exposure to pharmacological agents that inhibit various transport proteins suggested that characiform fish do not utilize the generally accepted mechanisms for Na+ transport that rely on some form of H+ extrusion. Examination of zebrafish transport at low pH suggest the rapid recovery may be due to a novel Na+/K+ exchanger, but after longer term exposure they may rely on a coupling of Na+/H+ exchangers and NH3 excretion. Further work is needed to clarify these mechanisms of transport and to find other acid-tolerant species to fully gain an appreciation of the diversity of physiological mechansisms involved.

Effect of water calcium, copper, and silver on branchial Na+ permeability in a characid and cichlid fish.

We tested the hypothesis that water Ca2+ is involved in control of branchial Na+ permeability in low pH tolerant convict cichlids and black neon tetras. We measured Na+ efflux in water with different Ca2+ concentrations during exposure to low pH, silver, and copper, at levels which are known to stimulate Na+ efflux. For convict cichlids at pH 7.5 exposure to 0 µmol L-1 Ca2+caused Na+ efflux to rise 2.5 times above controls at 100 µmol L-1 Ca2+. However, raising [Ca2+] to 500 µmol L-1 had no effect. Upon exposure to pH 3.5 (control [Ca2+]) Na+ efflux rose almost 5× and increasing the [Ca2+] 5-fold did not reduce the magnitude of stimulation. Exposure to 1 µmol L-1 silver and 25 µmol L-1 copper stimulated Na+ efflux 7×, and 2×, respectively. Raising [Ca2+] concentration during metal exposure halved the stimulation of Na+ efflux caused by silver, and eliminated the stimulation elicited by copper. For black neon tetras raising or lowering water [Ca2+] had no effect on Na+ efflux at pH 7.5. Exposure to pH 3.5 caused Na+ efflux to rise 2.5× but changing [Ca2+] had no effect. Exposure to 1 µmol L-1 silver, or 25 µmol L-1 copper caused Na+ efflux of tetras to rise 4-fold and 3-fold, respectively. Raising [Ca2+] during silver exposure reduced the stimulation of Na+ efflux by about 50%, but during copper exposure increased [Ca2+] had no effect on stimulation of Na+ efflux. These results suggest water Ca2+ plays a role in control of branchial Na+ permeability in cichlids, but perhaps not tetras. In addition, the silver and copper concentrations required to inhibit Na+ uptake and stimulate Na+ efflux were higher than the concentrations used on non-characids and non-cichlids, which indicates that our fish are much more tolerant of these metals.

Exposure to pH 3.5 water has no effect on the gills of the Amazonian tambaqui (Colossoma macropomum).

Tambaqui (Colossoma macropomum) are a model species for tropical fish physiology, but details are lacking about their ionoregulatory response to acid waters. To provide specifics, we measured unidirectional Na+ fluxes in low pH waters. Sodium influx ([Formula: see text]) was uninhibited during acute exposure to pH 4.5 and 3.5, and Na efflux ([Formula: see text]) rose only slightly at pH 3.5; net Na+ flux ([Formula: see text]) remained positive at all pH. Similarly, during 24 h transfer to pH 3.5 [Formula: see text], [Formula: see text], and [Formula: see text] were unchanged at all times. Taking a closer look at the mechanism of Na+ transport in the gills of tambaqui we found that [Formula: see text] was uninhibited by HMA, a Na+/H+-exchanger blocker, and Benzamil, a Na+-channel inhibitor, casting doubt on their role in Na+ uptake in this fish. Measurement of Na+/K+-ATPase (NKA) and H+-ATPase (VHA) activity showed that neither changed at low pH compared to measurements at pH 6.5. Western blot analysis of ATPase expression saw no changes in amount of NKA and VHA at low pH, and immunohistochemistry showed expression of both NKA and VHA on lamellae and interlamellar region of tambaqui gills and that both proteins co-localized to the same gill cells. Location of expression also did not change in low pH water. Amazingly, tambaqui seem unaffected by pH 3.5 water, making them one of the most acid-tolerant fish species examined so far. In addition, they appear to share key ionoregulatory traits with other fish of the order Characiformes, which suggest a common origin for the ionoregulatory attributes.

Examination of ionoregulatory characteristics of South American cichlids.

We examined ionoregulatory traits of four cichlid species from South America, oscars (Astronotus ocellatus), Tapajos cichlids (Geophagus sp.), Macmaster's dwarf cichlids (Apistogramma macmasteri), and keyhole cichlids (Cleithracara maronii), all inhabitants of ion-poor waters. Km values for Na+ transport in fish held in 100 µmol L-1 Na+ water ranged from 49 to 143 µmol L-1, and Jmax values spanned 450 to 1205 nmol g-1 h-1. After one month in 1000 µmol L-1 Na+ water, kinetic parameters for Na+ uptake in three of the four species acclimated, but only oscars displayed the "typical" pattern of higher Km and lower Jmax values. Low pH water inhibited Na+ uptake (JinNa) in all, and stimulated Na+ efflux (JoutNa) 2.5 to 3.5-fold in three of the four species. Oscars alone had had a measurable JinNa at pH 3.5 and no stimulation of JoutNa. We measured JinNa in oscars and keyhole cichlids during exposure to 100 µmol L-1 Ethoxzolemide (EZ), an inhibitor of carbonic anhydrase, and 1 mmol L-1 NH4Cl (HEA). EZ inhibited JinNa by about 50% and HEA reduced JinNa by 80-90%. These results suggest that Na+ uptake involves H+ extrusion. Acute exposure to 1 µmol L-1 CuSO4 and 60 nmol L-1 AgNO3 inhibited JinNa in both species by 30-85%. Exposure of oscars to 5-fold higher concentrations of both metals did not further inhibit JinNa, but it did stimulate JoutNa 50-150%. The response to metals of both species are similar to other species that have been examined.

Existence of homoclinic orbits and heteroclinic cycle in a class of three-dimensional piecewise linear systems with three switching manifolds.

In this article, we construct a kind of three-dimensional piecewise linear (PWL) system with three switching manifolds and obtain four theorems with regard to the existence of a homoclinic orbit and a heteroclinic cycle in this class of PWL system. The first theorem studies the existence of a heteroclinic cycle connecting two saddle-foci. The existence of a homoclinic orbit connecting one saddle-focus is investigated in the second theorem, and the third theorem examines the existence of a homoclinic orbit connecting another saddle-focus. The last one proves the coexistence of the heteroclinic cycle and two homoclinic orbits for the same parameters. Numerical simulations are given as examples and the results are consistent with the predictions of theorems.

South American characids share very similar ionoregulatory characteristics.

We examined ionoregulatory characteristics of four Characids from diverse locations in South America, emperor tetras (Nematobrycon palmeri), penguin tetras (Thayeria boehlkei), serpae tetras (Hyphessobrycon eques), and rosy tetras (Hyphessobrycon rosaceous). When held in 100 µmol L-1 Na+ water, tetras had Jmax values over 1100 nmol g-1 h-1, and Km values below 60 µmol L-1. When held in 1 mmol L-1 Na+ water kinetic parameters were unchanged. Low pH had no effect on Na+ uptake (JinNa). At pH 3.25, Na+ loss (JoutNa) was stimulated 35-85% in two of the four species. To test the linkage of JinNa to NH3 and H+ extrusion we measured JinNa during exposure to 1 mmol L-1 NH4Cl (HEA) and 100 µmol L-1 Acetazolemide (AZ). HEA stimulated JinNa of emperor tetras by 40%, but inhibited JinNa of penguin tetras by 50%; the two remaining species were unaffected. AZ (an inhibitor of carbonic anhydrase) inhibited JinNa of serpae tetras by 40%, but had no effect on the others. All tetras displayed ionoregulatory characteristics that are very similar to each other, which supports the argument that these physiological traits may be ancestral for this group and pre-date colonization of the Rio Negro. The novel finding that, Jmax and Km did not change after acclimation to 1 mM Na+ water indicates that, unlike in other species examined uptake is not plastic. The HEA and AZ results, along with pH insensitivity suggest Na+ uptake is not coupled to H+ extrusion or NH3 excretion and leaves the exact mechanism involved unclear.

The physiology of the Tambaqui (Colossoma macropomum) at pH 8.0.

The Tambaqui is a model neotropical teleost which is of great economic and cultural importance in artisanal fisheries and commercial aquaculture. It thrives in ion-poor, often acidic Amazonian waters and exhibits excellent regulation of physiology down to water pH 4.0. Curiously, however, it is reported to perform poorly in aquaculture at pH 8.0, an only slightly alkaline pH which would be benign for most freshwater fish. In initial experiments with Tambaqui of intermediate size (30-50 g), we found that ammonia excretion rate was unchanged at pH 4, 5, 6, and 7, but elevated after 20-24 h at pH 8, exactly opposite the pattern seen in most teleosts. Subsequent experiments with large Tambaqui (150-300 g) demonstrated that only ammonia, and not urea excretion was increased at pH 8.0, and that the elevation was proportional to a general increase in MO2. There was an accompanying elevation in net acidic equivalent excretion and/or basic equivalent uptake which occurred mainly at the gills. Net Na+ balance was little affected while Cl- balance became negative, implicating a disturbance of Cl- versus base exchange rather than Na+ versus acid exchange. Arterial blood pH increased by 0.2 units at pH 8.0, reflecting combined metabolic and respiratory alkaloses. Most parameters recovered to control levels by 18-24 h after return to pH 6.0. With respect to large Tambaqui, we conclude that a physiology adapted to acidic pH performs inappropriately at moderately alkaline pH. In small Tambaqui (4-15 g), the responses were very different, with an initial inhibition of ammonia excretion rate at pH 8.0 followed by a subsequent restoration of control levels. Elevated ammonia excretion rate occurred only after return to pH 6.0. Furthermore, MO2, plasma cortisol, and branchial vH+ATPase activities all declined during pH 8.0 exposure in small Tambaqui, in contrast to the responses in larger fish. Overall, small Tambaqui appear to cope better at pH 8.0, a difference that may correlate with their natural history in the wild.

Generation of multi-scroll attractors without equilibria via piecewise linear systems.

In this paper, we present a new class of dynamical system without equilibria which possesses a multiscroll attractor. It is a piecewise-linear system which is simple, stable, displays chaotic behavior and serves as a model for analogous non-linear systems. We test for chaos using the 0-1 Test for Chaos from Gottwald and Melbourne [SIAM J. Appl. Dyn. Syst. 8(1), 129-145 (2009)].

Ionoregulatory Characteristics of Non-Rio Negro Characiforms and Cichlids.

We examined ionoregulatory characteristics of two species of characiform fish and two species of cichlids that are not native to the Rio Negro, an extremely ion-poor, acidic tributary of the Amazon River, in order to gain insight into the origin of the specializations possessed by Rio Negro fish. The two characiform species examined, Congo tetras (Phenacogrammus interruptus) and black neon tetras (Hyphessobrycon herbertaxelrodi), had high-affinity/high-capacity transporters that produce high rates of uptake in dilute water. Na+ uptake for both was pH insensitive (down to pH 3.5). Exposure to 100 µmol L-1 phenamil had no effect on Na+ uptake in either species, while exposure to 1 mmol L-1 NH4Cl- (high external ammonia [HEA]) slightly stimulated Na+ uptake in Congo tetras. Exposure to "Na+-free" water significantly inhibited Na+ uptake (by 65%-85%) but had no effect on net ammonia flux. The two cichlid species examined, convict cichlids (Amatitlania siquia) and red point cichlids (Archocentrus sp.), had high-affinity but low-capacity transporters that yield low rates of uptake in dilute media. Sodium transport was pH sensitive and completely inhibited at pH 3.5. Phenamil exposure inhibited Na+ uptake by 60% in convict cichlids but had no effect on red point cichlids, and exposure to HEA reduced Na+ uptake in both species by 70%-85%. Exposure to "Na+-free" water reduced Na+ uptake by 80%-85%, and in convict cichlids it also reduced net ammonia flux by about 50%. The ionoregulatory characteristics described for both groups are strikingly similar to those for Rio Negro species, and we suggest that they may be ancestral physiological traits for these two groups. Further, if this is the case, it seems likely that these traits existed before the Rio Negro and may explain the great success of these species-rich groups in colonizing the river despite its challenging chemistry.

Germination and extrusion as combined processes for reducing phytates and increasing phenolics content and antioxidant capacity of Oryza sativa L. whole grain flours.

Whole rice (WR) products with low phytic acid (PA) content and enhanced bio-functional components were obtained by the combination of germination and extrusion processes. Germination conditions (24 h - 35 °C), with a previous soaking process (24 h - 20 °C), were chosen according to the remnant PA content and germination rate. Specific mechanical energy consumption, expansion, sensorial and mechanical hardness, specific volume, solubility, water absorption, free phenolic content (FPC) and antioxidant capacity were evaluated. Results indicated that 175 °C and 14 g 100 g(-1) of moisture were the most appropriate conditions to obtain expanded products and precooked flours based on germinated WR. Selected extruded product presented less PA content (821.6 9 ± 10.3 versus 695.2 0 ± 1.6 mg 100 g(-1)) and higher Fe bio-accessibility, FPC (45.2 9 ± 1.61 versus 66.3 5 ± 3.35 mg GAE g(-1)) and antioxidant capacity compared with WR (34.9 5 ± 0.8 versus 54.6 3 ± 1.6 µmol trolox g(-1)). Combining germination-extrusion processes could be a strategy to obtain expanded products or precooked flours based on WR with enhanced health benefits.

Effect of extrusion conditions on physicochemical and sensorial properties of corn-broad beans (Vicia faba) spaghetti type pasta.

Corn-broad bean spaghetti type pasta was made with a corn/broad bean flour blend in a 70:30 ratio, through an extrusion-cooking process (Brabender 10 DN single-screw extruder with a 3:1 compression ratio). The effect of temperature (T=80, 90 and 100°C) and moisture (M=28%, 31% and 34%) on the extrusion responses (specific consumption of mechanical energy and pressure) and the quality of this pasta-like product (expansion, cooking-related losses, water absorption, firmness and stickiness) was assessed. The structural changes of starch were studied by means of DSC and XRD. The extrusion-cooking process, at M=28% and T=100°C, is appropriate to obtain corn-broad bean spaghetti-type pasta with high protein and dietary fibre content and adequate quality. The cooking characteristics and resistance to overcooking depended on the degree of gelatinisation and formation of amylose-lipid complexes. The critical gelatinisation point was 46.55%; beyond that point, the quality of the product declines.

Gallbladder selection for histopathological analysis based on a simple method: a prospective comparative study.

INTRODUCTION: After a cholecystectomy, the current and traditional practice is to send each resected gallbladder to the pathologist for analysis. Some reports have suggested the possibility of selecting only those gallbladders that need to be analysed. The purpose of this study was to show a simple method for selecting which gallbladders should be sent to the pathologist. METHODS: A prospective comparative study was carried out. Two 'tests' were performed in 150 patients to detect or rule out gallbladder cancer. The first test included the patient's variables and a macroscopic gallbladder analysis performed by the surgeon (MGAS). The second test was the analysis performed by the pathologist. The results were compared. RESULTS: Of the 150 patients, 132 were women and 18 men; 130 were under 60 years old. One patient had inflammatory bowel disease, seven had changes on ultrasonography and in four cases intra-operative disturbances were observed. During the MGAS, disturbances were found in 30 patients. Eighty-one cases (54%) had at least one or more risk factors for gallbladder cancer.

The physiology of hyper-salinity tolerance in teleost fish: a review.

Hyper-saline habitats (waters with salinity >35 ppt) are among the harshest aquatic environments. Relatively few species of teleost fish can tolerate salinities much above 50 ppt, because of the challenges to osmoregulation, but those that do, usually estuarine, euryhaline species, show a strong ability to osmoregulate in salinities well over 100 ppt. Typically, plasma Na(+) and Cl(-) concentrations rise slowly or not at all up to about 65 ppt. At higher salinities ion levels do rise, but the increase is small relative to the magnitude of increase in concentrations of the surrounding water. A number of adjustments are responsible for such strong osmoregulation. Reduced branchial water permeability is indicated by the observation that with the exposure to hyper-salinities drinking rates rise more slowly than the branchial osmotic gradient. Lower water permeability limits osmotic water loss and greatly reduces the salt load incurred in replacing it. Still, increased gut Na(+)/K(+)-ATPase (NAK) activity is necessary to absorb the larger gut salt load and increased HCO(3) (-) secretion is required to precipitate Ca(2+) and some Mg(2+) in the imbibed water to facilitate water absorption. All Na(+) and Cl(-) taken up must be excreted and increased branchial salt excreting capacity is indicated by elevated mitochondrion-rich cell density and size, gill NAK activity and expression of chloride channels. Excretion of Na(+) and Cl(-) occurs against a larger gradient than in seawater and calculation of the equilibrium potential for Na(+) across the gill epithelium indicates that the trans-epithelial potential required for excretion of Na(+) climbs with salinity up to about 65 ppt before leveling off due to the increasing plasma Na(+) levels. During acute transition to SW or mildly hyper-saline waters, some species have shown the ability to upregulate branchial NAK activity rapidly and this may play an important role in limiting disturbances at higher salinities. It does not appear that the opercular epithelium, which in SW acts in a way that is functionally similar to the gills, continues to do so in hyper-saline waters. Little is know about the hormones involved in acclimation to hyper-salinity, but the few studies available suggest a role for cortisol, but not growth hormone and insulin-like growth factor. Despite the increased transport capacity evident in both the gill and gut in hyper-saline waters there is no clear trend toward increased metabolic rate. These studies provide a general outline of the mechanisms of osmoregulation in these species, but significant questions still remain.

Impact of ontogenetic changes in branchial morphology on gill function in Arapaima gigas.

Soon after hatching, the osteoglossid fish Arapaima gigas undergoes a rapid transition from a water breather to an obligate air breather. This is followed by a gradual disappearance of gill lamellae, which leaves smooth filaments with a reduced branchial diffusion capacity due to loss of surface area, and a fourfold increase in diffusion distance. This study evaluated the effects these changes have on gill function by examining two size classes of fish that differ in gill morphology. In comparison to smaller fish (approximately 67.5 g), which still have lamellae, larger fish (approximately 724.2 g) without lamellae took up a slightly greater percentage of O2 across the gills (30.1% vs. 23.9%), which indicates that the morphological changes do not place limitations on O2 uptake in larger fish. Both size groups excreted similar percentages of CO2 across the gills (85%-90%). However, larger fish had higher blood PCO2 (26.51.9 vs. 16.51.5 mmHg) and HCO3(-) (40.2 +/- 2.9 vs. 33.6 +/- 4.5 mmol L(-1)) concentrations and lower blood pH (7.58 +/- 0.01 vs. 7.70 +/- 0.04) than did smaller fish, despite having lower mass-specific metabolisms, suggesting a possible diffusion limitation for CO2 excretion in larger fish. With regard to ion regulation, rates of diffusive Na+ loss were about 3.5 times higher in larger fish than they were in smaller fish, despite the lowered branchial diffusion capacity, and rates of Na+ uptake were higher by about the same amount despite 40% lower activity of branchial Na+/K+-ATPase. Kinetic analysis of Na uptake revealed an extremely low-affinity (K(m) = 587.9 +/- 169.5 micromol L(-1)), low-capacity (J(max) = 265.7 +/- 56.8 nmol g(-1) h(-1)) transport system. These data may reflect a general reduction in the role of the gills in ion balance. Renal Na+/K+-ATPase activity was 5-10 times higher than Na+/K+-ATPase activity in the gills, and urine: plasma ratios for Na+ and Cl(-) were very low (0.001-0.005) relative to that of other fish, which suggested an increased role for dietary salt intake and renal salt retention and which was representative of a more "terrestrial" mode of ion regulation. Such de-emphasis of branchial ion regulation confers greatly reduced sensitivity of diffusive ion loss to low water pH. Ammonia excretion also appeared to be impacted by gill changes. Rates of ammonia excretion in larger fish were one third less than that in smaller fish, despite larger fish having blood ammonia concentrations that were twice as high.

[Zenker's esophageal diverticulum as differential diagnosis of paratracheal cystic lesion]. / Divertículo esofágico de Zenker como diagnóstico diferencial de lesión quística paratraqueal.

We report the case of a 52 years old patient with clinic of food regurgitation and some dysphagia without other added symptoms who was sent to our ENT consulting rooms. It was performed a cervicothoracic CT which informed as a paratracheal cystic lesion with differential diagnosis between esophageal or tracheal diverticulum. The possibility of that last one was discarted by a normal bronchoscopy.

[Sphenoidal sinus polyp-cyst as casual finding in a patient with severe and sudden retrocochlear hearing loss]. / Pólipo-quiste del seno esfenoidal como hallazgo casual en paciente con hipoacusia brusca severa retrococlear.

We present the case of a 56 years old female controlled in our ENT Department because of right sudden hearing loss, tinnitus and vertigo. The endoscopic exam was normal. Audiogram showed a severe neurosensorial hypoacusia and PEATC confirmed the so called hypoacusia suggesting a retrocochlear origin of it. As imaging tests an otic-craneal CT and IRM were asked for, which informed of the presence of a cystic lesion versus polyp in sphenoidal sinus of 15 x 10 mm without other alterations or significant pathology.

[Facial and oropharyngeal angioedema in patient with alimentary fish allergy. Diagnosis and treatment]. / Angioedema facial y orofaríngeo en paciente con alergia alimentaria a pescado. Diagnóstico y tratamiento.

Vegetal or animal food can produce hipersensibility reactions IgE mediated of diverse intensity. We report the case of a 54 years old woman without previous allergic antecedents who after eating frozen fish had to go to Emergencies due to angioedema especially in face and oropharynx. The ENT exploration by fibroscopia descarted laryngeal edema but the patient showed initially respiratory symptoms so she was treated with SC adrenalina and then steroids during her admission. The diagnosis of alimentary alergia would be confirmed after by Allergology with cutaneous test prick type.

[Cholesterol cyst-granuloma on petrous apex. Report of a case and differential diagnosis]. / Quiste-granuloma de colesterol de la punta del peñasco. Presentación de un caso y diagnóstico diferencial.

Cholesterol granulomas and cysts located on the petrous apex can course of a silent way during years. We describe one case assisted in our consulting rooms which was discovered after performing CT and MRI (with and without paramagnetic contrast) in a patient with vertigo associated to conscience loss without other symptoms. In the discussion is exposed which must be the differential diagnosis of this pathology.

[Cervical osteophytosis as cause of dysphagia. Forestier-Rotes Querol's disease]. / Osteofitosis cervical como causa de disfagia. Enfermedad de Forestier-Rotes Querol.

The so called Forestier-Rotes Querol's disease or diffuse idiopathic skeletal hyperostosis can affect the neck caused by osteophytos and ossification-calcification of the vertebral ligaments. The location in that region can produce dysphagia or hoarseness, among other symptoms, so that the patient can assist or be sent to ENT valoration. We are reporting a case of this pathology which was diagnosed in our hospital. Finally a bibliographic review is performed.

[Kartagener sindrome (primary ciliary dyskinesia). Report of a case and literature review]. / Síndrome de Kartagener (disquinesia ciliar primaria). Caso clínico y revisión de la literatura.

Kartagener syndrome (a clinical variant of primary ciliary dyskinesia) is a recessive autossomical disease characterized by the triad of chronic sinusitis, bronchiectasis and situs inversus with dextrocardia. We report one case described in a 8 years old boy who besides presented a seromucous otitis and bronchitis of repetition. Finally we performed a short bibliographic review at respect of this uncommon pathology.