Data regarding the typology and functional significance of the venous valves

Many authors described in detail the morphological features of human venous valves, but less their functional architecture. The present study provides additional information concerning the valvular anatomy, to enable its functional interpretation. The previously reported data and the author's results showed the regional distribution and characteristics of venous valves in different areas of the human body. Certain findings suggested a reorganization after birth of the venous valves which are frequently met in fetus. The close relation between hemodynamic mechanisms and the blood guiding structures may explain the changes (disappearance or persistence) of venous valves in some areas after birth. Significance of the rudimentary folds, resembling valves, is not yet elucidated. Based on his observations, the author attempted a new classification of the veins. The relations between density and morphological peculiarities of venous valves in different vein types showed that the constant valves were always involved in the local hemodynamics. Bardeleben's principles referring to the location and topographical arrangement of venous valves can be applied only to certain areas of the limbs, but not to other regions. In this paper there are described and functionally interpreted the venous valves of all territories of the human body.     

The structure of the intrapigmented aesthetes and the properiostracum layer in Callochiton achatinus (Mollusca: Polyplacophora)

The ultrastructure of the intrapigmented aesthetes which occur in specific areas of the different valves of Callochiton achatinus are described. The possible functions of the aesthete and the pigmented body are discussed in the light of their ultrastructure and the ecological requirements of the animal. The properiostracum in C. achatinus is unusually thick and has a structure very similar in appearance to that of collagen.     

SOME ASPECTS OF MORPHOLOGICAL VARIATION IN STEPHANODISCUS NIAGARAE (BACILLARIOPHYCEAE)1

Valves of S. niagarae var. niagarae Ehr. and S. niagarae var. magnifica Fricke from geographically dispersed sediment and plankton collections were observed by light microscopy and scanning electron microscopy (LM and SEM). Measurements made by LM can be arranged so that means and ranges of diameter, areolar density, or strial density intergrade from one population into the next. Mean diameter is negatively related to increasing areolar and strial densities. No unique features observable by SEM distinguish the two described varieties. Thus, S. niagarae var. magnifica, having large diameter valves with low areolar and strial densities, may represent one end of a trend in overall variation in S. niagarae. At the opposite extreme are the populations with small valves and high areolar densities which are often erroneously referred to as S. astraea. Type material of S. niagarae lies intermediate to these forms. Three populations considered in this study have distinct morphological characteristics. Valves from Yellowstone Lake sediments have spine placements distinctly different from valves of all other populations. Specimens from Lake Superior have nearly flat central areas. Ribs of valves from Grand Traverse Bay (Lake Michigan) are covered with granules.     

Osteopontin is associated with bioprosthetic heart valve calcification in humans

Calcification of non-osseous tissues such as heart valves or vessels is a major concern in clinical practice. The exact mechanism is still unknown. Numerous studies have shown that mineral deposits of crystalline hydroxyapatite within these tissues were associated with increased non-collagenous protein content. More recently osteopontin was found to be associated with calcification in living tissues such as vessels and native human aortic valves. The aim of this study was to determine whether or not non-collagenous proteins can also be found in non-living tissues such as glutaraldehyde-pretreatedporcine valves after implantation in humans. Thirty-eight glutaraldéhyde pretreated porcine bioprostheses were studied: 16 not implanted and 22 after 11 years of implantation in the aortic and mitral valve position in humans. In areas of calcification vizualized by Von Kossa staining and microradiography, immunostaining using polyclonal antibodies against calcium-bindingproteins showed osteopontin positive staining and no staining for osteocalcin, bone sialoprotein or osteonectin. In uncalcified areas and in non-implanted valves, staining for osteopontin or other calcium-binding proteins was negative. Western blot analysis of macroscopically calcified and uncalcified areas showed that several proteins were adsorbed in implanted valves and confirmed the presence of osteopontin in the calcified areas, while no immunolabelling was found in non-calcified areas, in uncalcified valves and in non-implanted valves. Thus the presence of osteopontin in the calcified areas of bioprosthetic heart valves implanted in human indicates that this protein is associated with bioprosthetic valvular calcification. Since these valves are made of non-living connective tissue, and no cell immunostained for osteopontin was found around the calcified area, this study suggests that a non-cellular mediated mechanism involving protein adsorption may play a role in bioprosthetic valvular calcification.     

The Ramonalinids: a new family of mound‐building bivalves of the Early Middle Triassic

Abstract: Ramonalina n. gen. is a large thick‐shelled bivalve abundant in mounds preserved in the Gevanim Formation (late Anisian, Middle Triassic) of southern Israel. This bivalve was an edgewise‐recliner with a flattened anteroventral (functionally basal) surface and partially fused valves. It is the basis of a new family, the Ramonalinidae, which is descended from the myalinids through adaptation to edgewise positioning. Ligamental attachment was inadequate to hold valves together on large adults, resulting in valve displacement followed by shell secretion in the apical area that fused valves together and caused irregular growth on abapical areas. The ramonalinids formed large, nearly monospecific mounds on firm mud substrates in shallow marine waters. These are the largest Middle Triassic bivalve mounds known.     

Two new species of the genus <Emphasis Type="Italic">Leptochiton</Emphasis> (Mollusca,Polyplacophora) from north-western Pacific

Two new species of the genus Leptochiton, L. сommandorensis sp. nov. and L. incubatus sp. nov. from north-western Pacific are described. Leptochiton сommandorensis differs from the congeners in having radial rows of granules in the lateral areas of intermediate valves, unicuspid dental cap on major lateral teeth of the radula, and dorsal scales with two ribs. Leptochiton incubatus differs from the congeners in having one aesthete pore in each granule, a shallow depression between the central and lateral areas of intermediate valves and between the antemucronal and postmucronal areas of the tail valve, and unicuspid head of major lateral teeth of radula. This species is brooding.     

Venous valves in the large branches of superior vena cava

In 97 human cadavers the valves of the following blood vessels were investigated with regard to their cusps and their sizes and positions: the internal jugular veins, the subclavian veins, the brachiocephalic veins, and the superior vena cava. The cusps of each of the valves, which consist of two or three parts, are neither always of equal size nor obligatorily sufficient. Unipartite valves may be sufficient as well as insufficient. Internal jugular veins: The inferior bulb of the internal jugular vein is provided with valves which in 6% of the cases consist of three parts, in 66% of two parts, and in 15% of only one cusp. The concave margins of most of them go down as far as the venous angle. The convex edges attached to the wall of the vein extend to a higher level on the right side than on the left. In 13% there do not exist any valves. Varieties are described separately in this paper. Subclavian veins: Valves are found along the length of the vessel. Only few of them reach the venous angle. In rare cases there exist two valves: one at the beginning, the other at the end of the subclavian vein. In 4% of the cases the valves consist of three, in 75% of two cusps. In 12% they are unipartite. In 9% there are no valves to be found. The right side is more often without valves than the left. Brachiocephalic veins: Only a minority of these vessels is provided with valves. Most of these consist of one cusp, are insufficient, and are situated in the left innominate vein.(ABSTRACT TRUNCATED AT 250 WORDS)     

Results of a comparative in vitro study of Duromedics and Björk-Shiley monostrut mitral heart valve prostheses

Two different mechanical heart valves with annulus diameters 21–29 mm, (five Björk-Shiley monostrut tilting disc valves and five Duromedics bileaflet valves) have been tested in pulsatile flow in the mitral position of a mock circulation. Reflux, pressure, and orifice area have been measured while cardiac output was varied between 2 and 6 1 min⁻¹. Insufficiency, mean orifice area, discharge coefficient, and performance and efficiency indices have been calculated. Mean values of insufficiency for the Björk-Shiley monostrut valves varied between 4.8 and 17.2% while the corresponding values for the Duromedics valves were in the range 6.1–17.3%. Mean values for orifice areas of the Björk-Shiley monostrut valves increased with the larger valve sizes from 101.1 to 210.2 mm²; for the Duromedics valves the area range was 134.5–262.9 mm². Because of the larger orifice areas the values of discharge coefficient and performance index for the Duromedic valves were higher than those for the Björk-Shiley monostrut valves. As the insufficiency of the two mechanical valves was similar, and the orifice area of the bileaflet valves was greater than that of the tilting disc valves, Duromedics valves gave higher values for the efficiency index, which varied between 0.31 and 0.39; for Björk-Shiley monostrut valves the index varied between 0.24 and 0.28 under the same test conditions. This hydrodynamic in vitro comparison of mechanical heart valves showed that the Duromedics bileaflet valves were superior to the Björk-Shiley tilting disc valves.     

Aurikirkbya wordensis (hamilton): ein vermutlich filtrierender palaeocopider ostracode

The valves ofAurikirkbya wordensis (Hamilton, 1942) from the Upper Permian, Word Formation of W Texas (USA), show a crenulated contact groove in the larger valve and smooth contact list in the smaller one. The right valve is usually the larger but occasionally inversion of valves take place. The contact elements of the free margin of valves are discussed in terms of functional morphology. In addition, the muscle-scar areas and the carapace outline have also been regarded. Based on the new discoveries, it is suggested thatA. wordensis was a nectobenthonic filter-feeder. The evidence from the valve interiors is not consistent with a platycopine position for the kirkbyacean taxa.

     

In-vitro fluid dynamic characteristics of the abiomed trileaflet heart valve prosthesis

The need for better and longer lasting trileaflet valves has led to the design and development of the Abiomed polymeric trileaflet valve prosthesis. In-vitro fluid dynamic studies on sizes 25 and 21 mm valves in the aortic position indicate an overall improvement in performance compared to the Carpentier-Edwards and Ionescu-Shiley tissue valves in current clinical use. The pressure drop studies yielded effective orifice areas of 1.99 and 1.54 cm2, and performance indices of 0.41 and 0.45 for the Nos. 25 and 21 valves, respectively. Leaflet photography studies indicated that the two valve sizes had maximum opening areas of 225 and 145 mm2, respectively, at a normal resting cardiac output. Steady and pulsatile flow velocity measurements with a laser-Doppler anemometer (LDA) system indicate that the flow field downstream of the Abiomed valve is jetlike and turbulent. Maximum mean square axial velocity fluctuations of 55 and 83 cm/s, and turbulent shear stresses of 220 and 450 N/m2 were measured in the immediate vicinity of the nos. 25 and 21 valves, respectively. The Abiomed valves studied had been originally configured for use in valved conduits, and it is therefore our opinion that further improvements can be made to the valve and stent design, which would enhance its fluid dynamic performance.     

A CAUTIONARY TALE: RAZOR SHELLS, ACORN BARNACLES AND PALAEOECOLOGY

Abstract:  The extant, introduced razor shell Ensis americanus (Binney) is a burrowing inhabitant of sandy, shallow-water substrates off the North Sea and Wadden Sea coasts of The Netherlands and adjacent areas. Three articulated shells with broken valves, collected from the strandline at Zandvoort, Noord-Holland, in April 2006 have dense skeletozoan infestations of the barnacle Balanus crenatus Brugière on the outer and inner surfaces of all valves. Such infestations must have occurred after death of the bivalve, decomposition of the soft tissues (but not the ligament) and disinterment of the shells. Larvae of B. crenatus settle in the spring, suggesting that these infestations are perhaps less than a year old, and testifying to the post-mortem persistence of the ligament and the density of skeletozoan infestation after a geologically brief duration. Such specimens would be a palaeoecological conundrum if fossilized; however, the ligament is likely to rot before final burial and the valves break further. Fossil specimens would probably be interpreted as valves that became encrusted on their inner and outer surfaces (balanuliths) during a long post-disarticulation residence on the sea floor.     

Comparison of Cocconeis pseudonotata sp. nov. with two closely related species,C. notata and C. diruptoides,from Posidonia oceanica leaves

Three Cocconeis Ehrenberg species, epiphytic on the leaves of Posidonia oceanica (L.) Delile, were studied by light and electron microscopy. A new species, C. pseudonotata, is described which is closely related to C. notata Petit and C. diruptoides Hustedt. Gross morphology and the presence of a sigmoid raphe and sternum are the characters shared by the three species, whereas the central areas of sternum and raphe-sternum valves, and the stria and areola densities are the main distinctive characters for the species when observed by light microscopy. Scanning and transmission electron microscopic observations revealed that the fine structure of areolae must be also considered in order to identify the species. Comparison among the three species has been carried out by observations on material from our samples, as well as on the type material of C. diruptoides and cleaned samples from the Hustedt collection. The study also provides new information on the geographical distribution of these species.     

Ventilatory movements of the abdomen and branchial apparatus in dragonfly larvae (Odonata: Anisoptera)

Use of cine-photography in the analysis of ventilatory movements has necessitated a reappraisal of the ventilatory patterns previously described in dragonfly larvae. Movements of the abdominal exoskeleton, monitored by cine-photography, phototransistor and strain gauge, are discussed in relation to known muscular activity. Internal movements of the branchial apparatus, which consists of two chambers and three valves, are also illustrated in the intact animal. The mechanism of "gulping" ventilation ( V _a) in dragonfly larvae is discussed.     

On Indiacypris luxata (Brady), a freshwater ostracod (Crustacea: Entomostraca) from Sri Lanka

Indiacypris luxata (Brady), a freshwater ostracod from Sri Lanka is described and both the valves and the limbs and soft parts are figured.     

Two new species of the diatom genusChaetoceros (Bacillariophyta)

Two new planktonic diatom species of the genusChaetoceros are described herein:Ch. octagonus andCh. rectus, from material of Baja California coasts and the Gulf of California, respectively;Ch. rectus was also found in a sample from Australian waters.Ch. octagonus is a robust species, with a characteristic pyramidal valve shape, heavily silicified valves and setae, and one central rimoportula on every valve in the chain; it is compared with related species, which show a similar morphology, especially by electron microscopy. It belongs into subg.Chaetoceros, sect.Borealia. Ch. rectus is placed in subg.Hyalochaete, and provisionally within sect.Anastomosantia. Its major characters are: chains, cells, and setae are delicate and fragile, cells are joined in the chain by a bridge which connects sibling intercalary setae, valves and setae are weakly silicified, and one rimoportula is present on terminal valves only. Comparison is made with another species of the same section.Ch. rectus shows a different manner of chain-forming within the genus than previously described in the literature.     

On the monomyarian, Acostaea rivoli and evolution in the family Etheriidae (Bivalvia: Unionacea)

Acostaea rivoli (Desh.) is an etheriid bivalve which occurs, cemented to the substrate, in the basin of the River Magdalena in Colombia. The animal, apart from the shell, is here first described and compared with the two closely related species, the similarly monomyarian Pseudomulleria dalyi (Smith) from Mysore, India and the dimyarian Etheria elliptica Lam. widely distributed in tropical Africa. Attaching at an unusually late stage and by either valve, all three pass from initial bilaterial symmetry to a state of extreme bilateral and– apart from Etheria –also antero-posterior asymmetry. In Acostaea (and Pseudomulleria ) this involves exclusively posterior and, because settlement is anterior end downward in a depression, topographically upward growth with a change of around 90 in the disposition of the valves as these flatten out over the substrate. This necessitates formation of a new hinge between the anterior spur which is composed of the earlier growth of both valves, and the horizontal extent of the upper valve. With loss of the anterior adductor, the monomyarian condition is achieved in a unique manner. Evidence indicates that the family Etheriidae arose from edentulous Unionidae with the adoption of a pleurothetic cemented habit, this permitting exploitation of a hard substrate often, although not invariably, in rushing water.     

Trace elemental distribution in ostracod valves. From solution ICPMS and laser ablation ICPMS to microprobe mapping: a tribute to Rick Forester

A historical perspective on our understanding of the formation of ostracod valves and what they consist of is presented here, together with the history of investigations on the chemistry of ostracod valves. It is now clear that ostracod valves are made of 3 distinct layers consisting of calcite crystallites/rhombs that are held together by a significant network of organic fibrils which may also contribute to the trace elemental composition of ostracod valves when analysed by solution chemistry. The outer epicuticle of ostracod valves, when well preserved such as in modern material, contributes to an enrichment in magnesium, and this ought to be taken into account when interpreting the Mg/Ca of ostracod valves for use with water temperature reconstructions. Recommendations about the analytical techniques used for chemical analysis of ostracod valves are presented.     

Description of the male of Sclerocypris tuberculata (Methuen, 1910) (Crustacea,Ostracoda, Megalocypridinae)

The male of Sclerocypris tuberculata (Methuen), thus far unknown, is here described. Relying on the morphology of the copulatory appendages and of the prehensile palps, it appears that this taxon belongs to a separate species group, together with S. zelaznyi and perhaps also S. sarsi. There are some interesting sexual dimorphic characters in the valve morphology: males have shorter valves with a dorsal margin which runs nearly parallel to the ventral one (more elongated valves with sloping dorsal margin in females) and there is lobe-like projection of the valve margin on the ventro-caudal corner of the LV in females which is lacking in the male. Furthermore, the female genital region has a very aberrant morphology, and all specimens from the present collection possess the tuberculated and noded valves.     

Hydrochemistry from Sr and Mg contents of ostracodes in Pleistocene lacustrine deposits,Baza Basin (SE Spain)

A reconstruction of the early Pleistocene paleohydrochemistry based on the Mg, Sr and Ca content of the Cyprideis valves is presented for shallow lacustrine sequences of the Baza basin. A large number of environmental changes in this marginal area has been recorded by the recurrent alternation of two fossil assemblages which differ in their salinity requirements. Measurements of the Sr/Ca and Mg/Ca ratios of individual calcite shells of Cyprideis show that the water in the higher saline stages (with thalassic organisms indicating marine-like conditions) was of non-marine origin. The Sr/Ca values of Cyprideis valves from sands deposited during a saline water phase show lower values than those from an overlying carbonate sequence which was formed under lower salinity conditions. These unexpected values are assumed to be the result of major changes in the chemical composition of the water in shallow, littoral ponded areas of a hydrologically complex lake. In the sequences that originated in these areas, Sr/Ca values may be used only as salinity indicators within each portion of the sequence formed in a single, continuous evolution. In more open areas, the wide fluctuations of Sr/Ca and Mg/Ca recorded in ostracodes from individual layers of rippled ostracode-shell sands probably reflect the mixing of valves from changing short-term environmental conditions.