scholarly journals A Comparative Study of Gill Ventilation in Marine Teleosts

1960 ◽  
Vol 37 (1) ◽  
pp. 28-45 ◽  
Author(s):  
G. M. HUGHES
Keyword(s):  
Time Course ◽  
Clupea Harengus ◽  
Pressure Curve ◽  
Suction Pump ◽  
Lower Jaw ◽  
Sea Bottom ◽  
Gill Ventilation ◽  
Pressure Changes ◽  
Conger Conger

1. Movements of the lower jaw and operculum have been recorded simultaneously with the associated pressure changes in the buccal and opercular cavities during breathing of the following species: Trachurus trachurus (L.), Clupea harengus L., Gadus merlangus L., Onos mustela (L.), Crenilabrus melops (L.), Cottus bubalis Euphrasén, Blennius ocellaris L., Trigla gurnardus L., Callionymus lyra L., Pleuronectes platessa L., Microstoinus kitt (Walbaum), Conger conger (L.), Syngnathus acus L. 2. In all species ventilation of the gills is achieved by the action of a buccal pressure pump and of opercular suction pumps. 3. The time course of the pressure changes indicates differences in the relative importance of the two pumps which are related to the habitat of the fish. The suction pump becomes of greatest importance in fishes which spend most of their lives on the sea bottom. 4. In several species the differential pressure curve does not include the brief period of reversal in pressure gradient found in most fishes so far investigated. Notable among these species are the two flatfishes investigated and in which there is some evidence for an active opercular valve. 5. In general, the results confirm the validity of Baglioni's classification of the respiratory mechanisms of teleost fishes.

scholarly journals The Mechanism of Gill Ventilation in Three Freshwater Teleosts

1958 ◽  
Vol 35 (4) ◽  
pp. 807-823 ◽  
Author(s):  
G. M. HUGHES
Keyword(s):  
Negative Pressure ◽  
Time Course ◽  
Phase 1 ◽  
Quantitative Relationship ◽  
Differential Pressure ◽  
Positive Pressure ◽  
Pressure Curve ◽  
Suction Pump ◽  
Opening And Closing ◽  
Pressure Changes

1. A study has been made of the respiratory movements of three species of freshwater fish. The time course of pressure changes in the buccal and opercular cavities was recorded and movements of the mouth and operculum plotted from ciné films taken simultaneously. 2. Opening and closing of the mouth precede respectively abduction and adduction of the operculum by about one-fifth of a cycle. 3. The most prominent part of the buccal pressure curve is a positive pressure associated with mouth closing. The size of a negative pressure as the mouth opens is small in the trout but may be relatively large in the tench. 4. Abduction of the operculum produces a marked negative pressure in the opercular cavity of all three species and there is a slight positive pressure during its adduction. 5. The respiratory system is divided into a buccal and two opercular cavities and the concept of gill resistances separating them is introduced. 6. The respiratory cycle is made up of four phases which succeed one another. These are: phase (1) opercular suction pump predominant; phase (2) transition with a reduction in differential pressure between the buccal and opercular cavities; phase (3) buccal pressure pump predominant; and phase (4) transition with reversal of differential pressure. 7. With the exception of phase (4), which occupies only about one-tenth of a cycle, the pressure in the buccal cavity exceeds that in the opercular cavity throughout the cycle. It is therefore concluded that water will flow across the gills for almost the entire cycle but may reverse for this brief period. The quantitative relationship between the pressures and the volume of water flowing across the gills during different parts of the cycle will depend upon the properties of the gill resistances.

The Mechanism of Gill Ventilation in the Dogfish and Skate

1960 ◽  
Vol 37 (1) ◽  
pp. 11-27 ◽  
Author(s):  
G. M. HUGHES
Keyword(s):  
Time Course ◽  
Gill Slit ◽  
Suction Pump ◽  
Pressure Pump ◽  
The Individual ◽  
Triakis Semifasciata ◽  
Leopard Sharks ◽  
Pressure Changes ◽  
Respiratory Movements ◽  
Branchial Region

1. The respiratory movements of the dogfish, Scyliorhinus (Scyllium) canicula (L.), and the ‘skate’, Raia clavata L. (thornback ray), have been studied by the use of cinematographic and mechanotransducer recording methods. Simultaneous determinations of the time-course of pressure changes in the oro-branchial and parabranchial cavities were also made by means of Hansen condenser manometers. 2. In both species movements of the mouth precede those of the spiracular valve and of the branchial region. Adduction and abduction of the branchial region spreads serially from the first to last gill slit in the dogfish, but movements of the individual gill arches are more nearly synchronous in the skate. Opening of the flap valves formed by extensions of the inter-branchial septa are synchronous in both species. 3. Water entering one side of the mouth leaves by the three posterior gill slits of the same side. Water entering the spiracle leaves through the anterior slits of the same side. This separation of flow is less marked in the skate. 4. The pressure curves recorded in all parts of the system have both positive and negative phases with respect to the external medium. The positive phase, associated with closing of the mouth and spiracle, is larger in the oro-branchial than in the parabranchial cavities and vice versa. The time-course of the pressure changes indicates that the flow across the gills is maintained by the action of a pressure pump in front and a suction pump behind. 5. The suction pump plays a more important role than the pressure pump in the skate and its contribution to the flow across the gills is by no means negligible in the dogfish. 6. The differential pressure curves suggest that the flow across the gills is continuous except in the dogfish for a brief period when the gradient is reversed. The absence of this reversal in the skate suggests that the external gill slit openings are controlled by an active mechanism. This is probably an adaptation to bottom-living habit. 7. All these observations relate to animals which are stationary with respect to the water. During swimming at a reasonable speed leopard sharks (Triakis semifasciata) have been observed to make few or no respiratory movements, although they immediately ventilate actively on coming to rest at the bottom of the aquarium.

QUANTITATIVE DETERMINATION OF ENDOGENOUS PGI2 RELEASE IN ANAESTHETIZED BEAGLE DOGS

1987 ◽  
Author(s):  
F Hermán ◽  
P Hadházy ◽  
K Magyar
Keyword(s):  
Time Course ◽  
Pressure Curve ◽  
Beagle Dogs ◽  
Filtration Pressure ◽  
Thromboxane Receptor ◽  
Arterial Blood ◽  
Constant Rate ◽  
Endogenous Release ◽  
Thromboxane Receptor Antagonist ◽  
Pressure Changes

A 30μm diameter pore size screen was inserted into an arteriovenous bypass system in anaesthetized, heparin-treated beagle dogs. The arterial blood was directed through the screen by a roller pump at a constant rate. As a result, the pressure proximal to the filter continuously increased (F.Hermdn et al.Thromb. Res.44 /1986/,575). The concentration of proximally infused PGI2 that stabilized the filtration pressure curve (pressure stabilizing concentration= PSC) was determined. If it was low enough (between 0.4 and 1.5 nmol/1) we administered the PGI2-releaser bradykinin (1/ug/kg), angiotensin II (0.5/ug/kg) or ADP (20/ug/kg) in bolus dose intravenously. Together with the cnanges in blood pressure, we observed a transient decrease in filtration pressure. From the pressure changes, based on the previously determined PGI2 concentration-res-ponse relationship, we estimated the amounts of released PGI2 as well as the time course of this release. Indomethacin (2 mg/kg i.v.) significantly decreased the PSC for exogenous PGI2 thereby increasing the sensitivity of the method; the release of PGI2 was abolished. The sensitivity of the method could also be increased by infusing BM.13.177 - an endoperoxide, thromboxane receptor antagonist - proximal to the filter (final concentration: 1-10/ug/ml). This substance did not affect the release of PGI2.We conclude that by using this technique the endogenous release of prostacyclin can be continuously determined provided that PGI2 level exceeds 50 pg/ml.

scholarly journals Identification and classification of cis-regulatory elements in the amphipod crustacean Parhyale hawaiensis

2021 ◽  
Author(s):  
Dennis A Sun ◽  
Nipam H Patel
Keyword(s):  
Gene Expression ◽  
Genome Annotation ◽  
Time Course ◽  
Regulatory Elements ◽  
Rna Seq ◽  
Genome Wide ◽  
Long Read ◽  
Amphipod Crustacean ◽  
Accessible Chromatin

AbstractEmerging research organisms enable the study of biology that cannot be addressed using classical “model” organisms. The development of novel data resources can accelerate research in such animals. Here, we present new functional genomic resources for the amphipod crustacean Parhyale hawaiensis, facilitating the exploration of gene regulatory evolution using this emerging research organism. We use Omni-ATAC-Seq, an improved form of the Assay for Transposase-Accessible Chromatin coupled with next-generation sequencing (ATAC-Seq), to identify accessible chromatin genome-wide across a broad time course of Parhyale embryonic development. This time course encompasses many major morphological events, including segmentation, body regionalization, gut morphogenesis, and limb development. In addition, we use short- and long-read RNA-Seq to generate an improved Parhyale genome annotation, enabling deeper classification of identified regulatory elements. We leverage a variety of bioinformatic tools to discover differential accessibility, predict nucleosome positioning, infer transcription factor binding, cluster peaks based on accessibility dynamics, classify biological functions, and correlate gene expression with accessibility. Using a Minos transposase reporter system, we demonstrate the potential to identify novel regulatory elements using this approach, including distal regulatory elements. This work provides a platform for the identification of novel developmental regulatory elements in Parhyale, and offers a framework for performing such experiments in other emerging research organisms.Primary Findings-Omni-ATAC-Seq identifies cis-regulatory elements genome-wide during crustacean embryogenesis-Combined short- and long-read RNA-Seq improves the Parhyale genome annotation-ImpulseDE2 analysis identifies dynamically regulated candidate regulatory elements-NucleoATAC and HINT-ATAC enable inference of nucleosome occupancy and transcription factor binding-Fuzzy clustering reveals peaks with distinct accessibility and chromatin dynamics-Integration of accessibility and gene expression reveals possible enhancers and repressors-Omni-ATAC can identify known and novel regulatory elements

The Effects of External Salinity on the Drinking Rates of the Larvae of Herring, Plaice and Cod

1988 ◽  
Vol 138 (1) ◽  
pp. 1-15 ◽  
Author(s):  
P. TYTLER ◽  
J. H. BLAXTER
Keyword(s):  
Time Course ◽  
Gadus Morhua ◽  
Sea Water ◽  
Fluorescein Isothiocyanate ◽  
Yolk Sac ◽  
Clupea Harengus ◽  
Larval Stages ◽  
First Feeding ◽  
Fluorescein Isothiocyanate Dextran ◽  
External Salinity

Drinking responses to salinity change in the larvae of herring (Clupea harengus L.), plaice (Pleuronectes platessa L.) and cod (Gadus morhua L.) were measured from the time course of uptake of dextran labelled with tritium, following immersion in solutions of 32‰ and 16‰ sea water. The yolk sac and first feeding larval stages of all three species drink in both salinities. Furthermore, post-yolk sac stages appear to adjust their drinking rates to compensate for different salinities in a manner similar to that of the adults. Drinking rates in 32‰ sea water are approximately double those in 16‰. Mass-related drinking rates of larvae are higher than those in adults, but the differences do not match the differences in surface area to mass ratios, suggesting that larval skin is less permeable to water than is adult gill epithelium. Water absorption is indicated by the evidence of concentration of dextran in the gut. The estimates of drinking rates from tritiated dextran uptake are supported by epifluorescence microscopical measurements of the uptake of fluorescein isothiocyanate dextran.

scholarly journals Pharmacokinetics and pharmacodynamics of natalizumab in pediatric patients with RRMS

2019 ◽  
Vol 6 (5) ◽  
pp. e591 ◽  
Author(s):  
Angelo Ghezzi ◽  
Giancarlo Comi ◽  
Luigi Maria Grimaldi ◽  
Lucia Moiola ◽  
Carlo Pozzilli ◽  
...  
Keyword(s):  
Safety Profile ◽  
Time Course ◽  
Pediatric Patients ◽  
Short Term ◽  
Elimination Phase ◽  
Relapsing Remitting ◽  
Distribution Phase

ObjectiveThis phase I study investigated pharmacokinetic (PK) and pharmacodynamic (PD) profiles of natalizumab in pediatric patients with relapsing-remitting MS (RRMS).MethodsPediatric patients with RRMS who were prescribed natalizumab 300 mg IV every 4 weeks were enrolled. Blood samples were collected on days 1, 2, 8, 15, and 22 and at weeks 4, 8, 12, and 16 to estimate PK parameters; PD properties were evaluated by measuring α4-integrin saturation and lymphocyte counts over time. Natalizumab's safety profile was also evaluated.ResultsPK parameters were similar to those reported in adult patients; natalizumab concentrations peaked approximately 1 day after infusion in most of the participants (Cmax 142.9 μg/mL, AUClast 47389.4 hr*μg/mL), followed by a biphasic decline with a rapid distribution phase and a slow elimination phase, with a terminal half-life of 215.1 hours. In terms of PD, both time course and magnitude of α4-integrin saturation and increase in lymphocyte counts were similar to those observed in adults. During the 16-week study follow-up, 3 adverse events attributed to natalizumab were observed; no unexpected safety events occurred.ConclusionsPK profile, α4-integrin saturation, lymphocyte counts, and safety observed in these pediatric patients are comparable to those reported in adults.Classification of evidenceThis study provides Class I evidence that natalizumab PK/PD parameters and safety profile are similar in adults and pediatric patients in the short term. Longer studies, also including a larger number of younger subjects (aged 10–12 years), are required to further inform about long-term PK and PD parameters in pediatric patients with MS.

Spontaneous healing of traumatic tympanic membrane perforations in man: A century of experience

1992 ◽  
Vol 106 (12) ◽  
pp. 1037-1050 ◽  
Author(s):  
Søren Kristensen
Keyword(s):  
Tympanic Membrane ◽  
Healing Rate ◽  
Reference Value ◽  
Spontaneous Healing ◽  
Clinical Value ◽  
Post Injury ◽  
Tympanic Membrane Perforations ◽  
Pressure Changes ◽  
Perforated Tympanic Membrane

AbstractWidespread controversy exists concerning the treatment of traumatic tympanic membrane perforations. To elucidate the issue, a reference value for the rate of spontaneous tympanic membrane closure in man, to which the healing rates following different techniques of early surgical repair should be compared, was established on the basis of a review of more than 500 texts covering a century's literature on the traumatically perforated tympanic membrane. The spontaneous healing rate appeared to be close to 80 (78.7 per cent) in 760 evaluable cases of traumatic tympanic membrane perforations of all sorts diagnosed within 14 days post injury. A relative, causal-related variation of spontaneous healing could be demonstrated, and a pathogenetic classification of direct traumatic tympanic membrane perforations into ruptures induced by air-pressure changes, heat or corrosives, solids, and water pressures, is of proved clinical value and may have medico-legal validity. There is an obvious need for clinically controlled studies on the spontaneous healing of all kinds of traumatic perforations of the tympanic membrane in humans, and important elements in the design of future studies are advocated.

scholarly journals XIII. Researches on the structure, organization, and classification of the fossil reptilia. -Part IX., Section 3. On diademodon

1894 ◽  
Vol 185 ◽  
pp. 1029-1041 ◽  
Keyword(s):  
South African ◽  
Cape Town ◽  
Shoulder Girdle ◽  
Middle Region ◽  
The South ◽  
The West ◽  
Limb Bones ◽  
Lower Jaw

The South African fossils with broad, flat, tuberculate tooth-crowns of mammalian type all from the eastern part of Cape Colony. Some of the most interesting are known from fragments, which indicate nothing but the middle region of the sail. They are apparently extremely rare. Two species, with teeth well preserved, found ten years ago by Dr. Kannemeyer, at Wonderboom, and presented to South African Museum, Cape Town, where they were brought under my notice by Peringuey. Others were found in a fragmentary condition by Mr. Alfred of Aliwal North, to the west of that town, in a bed which appeared to me be reconstructed. There is no doubt that the fossils are from the upper part of te Karroo formation, probably of Permian age, and below the Stormberg beds, in Saurischian fossils are found allied to those of the Trias of Europe. If the teeth had occurred isolated, without the means of demonstrating their rsemblance to Theriodonts, by comparison of what remains of the skull, it would have legitimate to have referred them to Mammals. There is no evidence of affinity Accept resemblances to Theriodonts, which show that the skull had pre-frontal and frontal bones, and therefore may be inferred to have had the lower jaw composite. The teeth are such as might be expected, perhaps, in a Monotreme Mammal, their interest is therefore the greater that there is no ground for suspecting them be mammalian, other than a general resemblance of the crown to the crowns of true teeth of Ornithorhynchus. That teeth of this type should occur in a group animals in which the shoulder-girdle and pelvis have monotreme characters, and in hich the principal limb bones are intermediate in character between Monotremes Marsupials, is evidence of a closer approximation between Mammals and Pep tiles has been manifest. And so far as I am aware the only Theriodont characters remaining to distinguish these animals from Mammals are the composite lower which is covered externally by the dentary bone along its whole length, and the resence of the pre-frontal, post-frontal, and transverse bones in the skull.

scholarly journals V. Researches on the structure, organisation, and classification of the fossil reptilia. Part IX. Section 1. On the therosuchia

1894 ◽  
Vol 55 (331-335) ◽  
pp. 224-226
Keyword(s):  
Lower Jaw

This paper discusses the classification of reputed Permian and Triassic Reptilia which have been referred to the Anomodontia as Theriodonts. Lycosaurus , as the genus placed first on the Sir R. Owen’s list, is accepted as the type of the Theriodontia. The species Lycosaurus curvimola is regarded as the type of the genus, being the only species in which its characters are fully shown. Galesaurus planiceps , which was the type of the Cynodontia, is probably distinct from Nythosaurus larvatus ,and from Sir R. Owen’s second type of Galesaurus planiceps of 1887, which is referred to as Thrinaxodon liorhinus . Ælurosaurus felinus agrees with Galesaurus in having a transverse development of bones of the palate, regarded as palatine and transverse, which abut toward the inner side of the lower jaw.

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