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PubMed2001

Colocalization of CaM KII and MAP kinase on architectural elements of the mouse egg: potentiation of MAP kinase activity by CaM KII.

The conversion of the egg to a zygote requires the initiation of several signaling pathways that act in an orchestrated fashion to rapidly remodel the egg. Architectural elements within the egg can serve to localize components of these signaling pathways and colocalization of such components provides the opportunity for interaction between different signaling pathways. This study examines the localization as well as the state of activation of two different kinases, MAP kinase and calcium/calmodulin-dependent protein kinase II (CaM KII). The meiotic spindle serves as a site for enrichment of these kinases. However, activated MAP kinase and activated CaM KII exhibit a developmental stage-specific pattern of localization that represents a subset of the area occupied by the distribution of the total mass of MAP kinase and CaM KII. Suppression of CaM KII activity results in reduction in the amount of MAP kinase as well as a decreased level of activity of MAP kinase. Since CaM KII becomes active as a result of fertilization, the former kinase could serve to potentiate MAP kinase activity and the colocalization of these two kinases may facilitate such an interaction.

Animals↗
PubMed2002

Supramolecular synthesis through dihydrogen bonds: self-assembly of controlled architectures from NaBH4 x poly(2-hydroxyethyl)cyclen building blocks.

A systematic investigation of molecular structures/supramolecular organization relationships in dihydrogen-bonded complexes comprising NaBH4 and poly-2-hydroxyethyl-cyclen (poly-HEC) building blocks is reported. Like in the prototype compound 1, a (NaBH4-poly-HEC)2 dimeric arrangement has been found in the analogous structures 3 and 5, but not in compound 2, which lacks dihydrogen bonds. The exact connectivity of the dimers is determined by a complex interplay of noncovalent interactions such as OH...HB dihydrogen bonds, OH...O conventional hydrogen bonds, Na-O and Na-N coordinative bonds, and dispersion interactions. The persistent recurrence of this general supramolecular motif permits controlled assembly of extended networks with desired architectures, by the use of appropriate spacers for linking the dimers, as demonstrated by the solid-state structure of 7. Additionally, the intrinsic solid-state reactivity of these dihydrogen-bonded networks makes this approach a promising strategy for the rational construction of functional extended covalent solids.

Journal Article↗
PubMed1996

Genetic architecture of common multifactorial diseases.

The purpose of this paper is to foster a dialogue among those interested in the genetic analysis of common chronic diseases. The need for an alternative to the Cartesian-Mendelian research strategy is discussed. A biological model that considers an individual's health to be an emergent property of a complex adaptive system is presented. A review of the contribution of the gene coding for apolipoprotein E to the genetic architecture of measures of lipid metabolism documents that an individual's coronary artery health has all the features expected of a complex adaptive system. Suggestions for enhancing our ability to use genetic information to predict onset, progression and severity of disease are offered.

Apolipoproteins E↗
PubMed1984

The ultrastructural organization and architecture of basement membranes.

Basement membranes are ubiquitous complex, multicomponent structures having diverse functions. They are morphologically distinct and exhibit specific structural details including the lamina rara and lamina densa. In addition, the interstitial stroma abutting the lamina densa has a unique organization. While the composition of basement membranes is still incompletely known, several components have been identified, including collagen types IV and V, laminin and heparan sulphate proteoglycan. High resolution immunoelectron microscopic studies have allowed the development of various models of the organization and architecture of the basement membrane, suggesting specific localizations of the various collagen types and specific domains of the collagen molecules, laminin and other components. In addition, high resolution metal shadow casting techniques have allowed the development of molecular models of specific components of the basement membrane and methods of studying the domain structure and interactions of these components.

Animals↗
PubMed1980

Three-dimensional architecture of the cortical region of the Golgi apparatus in rat spermatids.

Glutaraldehyde-fixed testes were impregnated with the Ur-Pb-Cu technique of Thiéry and Rambourg ('76) or postfixed in ferrocyanide-reduced osmium (Karnovsky, '71). Thin and thick (0.5 micron) sections were examined with a Philips 400 electron microscope at 80 or 100 kv. Stereopairs were prepared from pictures of the same field after tilting the specimen every 6 degrees from the -45 degree to the +45 degree position of EM goniometric stage. The cortex of the compact hemispherical Golgi apparatus of young spermatids (steps 2-8) was found to be composed of saccular and intersaccular regions similar to those described in the Golgi apparatus of Sertoli cells (Rambourg et al., '79). In the saccular region, the stacks were composed of three to nine parallel saccules perforated with pores of various dimensions. On the mature or trans-face of the stack, one or two membranous elements with a wider lumen were either closely applied to the overlying saccules or were separated from them and intermixed with the vesicular components of the medulla. On the forming or cis-face of the stack, three or four saccules were frequently interrupted by gaps in register from one saccule to another. In three dimensions, these gaps appeared as pan-shaped spaces or "wells," often containing a few vesicles. Immediately overlying the first saccule on the cis-face, a regular network of anastomotic tubules was present, corresponding to the cis-osmiophilic element observed in other cell types. In the intersaccular region, membranous tubules connected to the edges of the saccules branched, intertwined, anastomosed, and bridged adjacent stacks of saccules. Such membranous tubules bridged saccules with the cis-osmiophilic element or saccules of the same stack. Between the ER cisternae capping the surface of the Golgi apparatus and the cis-network of anastomotic tubules, there was a space called the peripheral Golgi region containing small vesicles and membranous tortuous tubules. The vesicles were frequently arranged in clusters that were capped by an ER cisterna and displayed a size gradient from the periphery to the center of the cluster. Thus, although there were similarities between the three-dimensional architectures of the Golgi apparatus in Sertoli cells and young spermatids (e.g., saccular and intersaccular regions), several structural features distinguished the spermatid's Golgi apparatus.

Animals↗
PubMed1984

Microvascular architecture of the pampiniform plexus-testicular artery system in the rat: a scanning electron microscope study of corrosion casts.

The vascular architecture of the rat pampiniform plexus was studied by scanning electron microscopy of vascular corrosion casts. The plexus consists of a thick bundle of many anastomosing veins that entirely and closely surround the convoluted segments of the testicular artery. This specially developed close contact of the pampiniform plexus with the testicular artery may allow heat exchange between the plexus and the artery to maintain the cooled condition of the testis. The epididymal arteries are also closely surrounded by the networks of the epididymal veins. It is likely that heat exchange may operate even between these epididymal vessels. The ductus deferens is provided with no vascular channels for such heat exchange. A loose or coarse capillary network is always observed between the testicular artery and the pampiniform plexus. This network is supplied by the epididymal arteries and drains into the pampiniform plexus.

Animals↗
PubMed1984

Architectural design and fiber-type distribution of the major elbow flexors and extensors of the monkey (cynomolgus).

Because the architectural and biochemical properties of skeletal muscle dictate its force, velocity, and displacement properties, the major extensors (triceps brachii) and flexors (biceps brachii, brachialis, and brachioradialis) of the elbow in a primate (cynomolgus, monkey) were studied. Functional cross-sectional areas (CSA) were calculated from muscle mass, mean fiber length (normalized to a 2.20 microns sarcomere length), and angle of fiber pinnation measurements from each muscle. Fiber-type distributions were determined and used as a gross index of the biochemical capacities of the muscle. The extensor group had a shorter mean fiber length (31 vs. 47 mm), a larger CSA (13 vs. 8 cm2), and a higher overall percentage of slow-twitch fibers (47 vs. 26%). Consequently, the elbow extensors had a relatively greater potential for force production and force maintenance than the flexors. In contrast, the flexors were designed to optimize their length-velocity potentials; i.e., they had relatively long fibers and a higher fast-twitch fiber composition than the extensors. These morphologic differences between antagonistic muscle groups should be considered when evaluating the motor control mechanisms regulating reciprocal movements about the elbow.

Animals↗
PubMed1985

Dynamic histology of the antral epithelium in the mouse stomach: I. Architecture of antral units.

The architecture of the pure mucous units of the pyloric antrum was investigated in 3- to 4-month-old CD1 mice. Units were serially cut in cross section and stained by a method combining the periodic acid-Schiff sequence, a modified Grimelius's silver nitrate procedure, and Regaud's hematoxylin. A total of 195 units were then reconstructed. Of these, six were cast in polyester resin and 189 were two-dimensionally reproduced on graph paper. The reconstructions showed antral units to be divided among three main classes. The first class, which contained 32% of the units, consisted of fingerlike tubules referred to as "singlets." Three types of singlets were observed. The first or type A, which represented 76% of the singlets, was divisible into three successive portions: a pit (foveola) opening onto the mucosal surface and lined by mucous cells referred to as pit cells, an isthmus continuous with the pit and containing immature proliferative mucous cells, and a gland forming the blind end of the tubule and lined by mucous cells referred to as gland cells. Type B (14% of singlets) was similar to type A except that its gland was forked. Type C (10% of singlets) differed by the absence of a gland. The units of the second class, which contained 53% of the total number, were joined together along part of their length and were named "multiplets." Most of them (90%) were organized into clusters of two, and 10% into clusters of three. In the joined portion, the epithelial cells of the adjacent units were in contact through junctional complexes and, therefore, were not separated by basement membranes. Otherwise the units showed the same component parts as in singlets. Also, as in singlets, the majority of the units were type A and a few were type B or C. The units of the third class, or "intermediates," consisted of tubules which exhibited a branching process. This process was of variable length but could include gland, isthmus, and sometimes pit. Thus, the process duplicated a varying proportion of the unit. In conclusion, the pure mucous units of the antrum exhibit various patterns which have been designated singlet, multiplet, or intermediate. It is proposed that these three patterns are related and represent temporal differences in the duplication and production of new units. Based on this assumption, a model has been elaborated to depict the likely sequence in the proliferation of pure mucous units. It is proposed that this proliferation takes place in the antrum of young adult mice.

Animals↗
PubMed1986

Architecture of the masticatory apparatus in eastern raccoons (Procyon lotor lotor).

The structure and function of the masticatory apparatus of raccoons resemble those found in carnivores. In this study, the architecture of the skull, dentition, and masticatory apparatus is described, and a model is proposed that suggests a mechanism used by raccoons to reduce different foods. The model suggests that jaw movements are similar to those of cats, the posterior regions of the superficial and deep parts of the temporalis and the anterior region of the medial pterygoid generate horizontal jaw movements, and the anterior portions of the superficial and deep temporalis as well as portions of the masseteric complex generate vertical closing movement. The distributions of slow, fast fatigable, and fast fatigue-resistant fibers for the temporalis and masseteric complex are related to the possible actions of these muscles during mastication, as are the regional cross-sectional areas of the masticatory muscles.

Animals↗
PubMed1988

Ontogeny of architectural complexity in embryonic quail visceral arch muscles.

Understanding the mechanisms of muscle pattern formation requires that the complete sequence of ontogenetic events be defined, particularly in the emergence of architectural complexity and in the spatial relations between muscles and skeletal elements. This analysis of visceral arch myogenesis in quail (Coturnix coturnix japonica) embryos identifies the location of premuscle condensations and subsequent segregation of individual muscles, documents the initial orientation of myofibers and changes in alignment associated with maturation, and describes the spatial and temporal relations between muscle development and the formation of connective tissues. Premuscle condensations form within the visceral arches on embryonic days 2-4, before skeletal elements make their appearance. Discrete muscles may form from the subdivision of a muscle mass after fiber orientations have been established (e.g., jaw adductor and hyobranchial muscles) or by the segregation of a mesenchymal cluster from the condensation prior to the appearance of oriented fibers (e.g., protractor, muscle of the columella). The rate and pattern of subsequent muscle maturation are closely associated with the development of the hard tissues. Myogenesis in 4-9-day embryos centers around the quadrate cartilage, the retroarticular process of the mandibular (Meckel's) cartilage, and the epibranchial cartilage. Muscles form attachments on these elements and remain without additional attachments until the appropriate elements (e.g., otic capsule, pterygoid bone) develop. No single description of myogenic events applies to all visceral arch muscles, nor is there an arch-specific pattern of ontogeny. Rather, each muscle has distinctive characteristics based on its spatial relations within the developing head.

Animals↗
PubMed1986

Architectural and histochemical diversity within the quadriceps femoris of the brown lemur (Lemur fulvus).

Physiologically related features of muscle morphology are considered with regard to functional adaptation for locomotor and postural behavior in the brown lemur (Lemur fulvus). Reduced physiological cross-sectional area, estimated maximum excursion of the tendon of insertion, length of tendon per muscle fasciculus, and areal fiber type composition were examined in the quadriceps femoris in order to assess the extent of a "division of labor" among four apparent synergists. Each of these four muscles in this prosimian primate displays a distinguishing constellation of morphological features that implies functional specialization during posture and normal locomotion (walk/run, galloping, leaping). Vastus medialis is best suited for rapid whole muscle recruitment and may be reserved for relatively vigorous activities such as galloping and leaping (e.g., small cross-sectional area per mass, long excursion, predominance of fast-low oxidative fibers, relatively little tendon per fasciculus). In theory, rectus femoris could be employed isometrically in order to store elastic strain energy during all phasic activities (e.g., large cross-sectional area per mass, short excursion, predominance of fast-high oxidative fibers, large amount of tendon per fasciculus). Vastus intermedius exhibits an overall morphology indicative of a typical postural muscle (e.g., substantial cross-sectional area, short excursion, predominance of slow-high oxidative fibers, large amount of tendon per fasciculus). The construction of vastus lateralis reflects an adaptation for high force, relatively high velocity, and resistance to fatigue (e.g., large cross-sectional area, long excursion, most heterogeneous distribution of fiber types, large amount of tendon per fasciculus); this muscle is probably the primary contributor to a wide range of locomotor behaviors in lemurs. Marked dramatic architectural disparity among the four bellies, coupled with relative overall fiber type heterogeneity, suggests the potential for exceptional flexibility in muscle recruitment within this mass. One interpretation of this relatively complex neuromuscular organization in the brown lemur is that it represents an adaptation for the exploitation of a three-dimensional arboreal environment by rapid quadrupedalism and leaping among irregular and spatially disordered substrates.

Animals↗
PubMed2004

Grid-type metal ion architectures: functional metallosupramolecular arrays.

Recent advances in supramolecular coordination chemistry allow access to transition-metal complexes of grid-type architecture comprising two-dimensional arrays of metal ions connecting a set of organic ligands in a perpendicular arrangement to generate a multiple wiring network. General design principles for these structures involve the thermodynamically driven synthesis of complex discrete objects from numerous molecular components in a single overall operation. Such supramolecular metal ion arrays combine the properties of their constituent metal ions and ligands, showing unique optical, electrochemical, and magnetic behavior. These features present potential relevance for nanotechnology, particularly in the area of supramolecular devices for information storage and processing. Thus, a dense organization of addressable units is represented by an extended "grid-of-grids" arrangement, formed by interaction of grid-type arrays with solid surfaces.

Journal Article↗
PubMed1982

Isolation of human erythrocyte inside-out vesicles alters their molecular architecture.

Inside-out (I.O.) vesicles isolated from human erythrocyte ghosts induced to endocytose have been used for biochemical studies to determine localization of molecules within the membrane. It was the purpose of this study to examine such vesicles by freeze-etch electron microscopy to determine the architecture of the peripheral proteins on the protoplasmic surface. Examination of the I.O. vesicles while still in the interior of the ghosts showed that a globular material was randomly distributed on the outer surface (protoplasmic surface of the original plasma membrane) of the I.O. vesicles. The random distribution of the globular material becomes altered, however, if the I.O. vesicles are isolated from the ghosts by shearing and centrifugation. Freeze-etching of these isolated I.O. vesicles revealed that the globular material was now clustered on the protoplasmic surface (PS), as were the intramembranous particles (IMPs) in the extracellular face. Thus, the lateral mobility of the IMPs is dependent upon the distribution of molecules at the protoplasmic surface of the membrane. Moreover, this change in distribution of the globular material at the surface is not due to a partial loss of major membrane proteins, because SDS-polyacrylamide gel electrophoresis revealed that equal amounts of the major proteins were present in nonisolated vesicles as compared to isolated vesicles. Although isolated I.O. vesicles have been used extensively to demonstrate that glycoproteins span the membrane, these results suggest that one should cautiously interpret data obtained from such isolated vesicles in view of the fact that there is an alteration of the distribution and perhaps configuration of molecules at the PS following isolation of I.O. vesicles.

Electrophoresis, Polyacrylamide Gel↗
PubMed1987

Three-dimensional architecture of sarcoplasmic reticulum and T-system in human skeletal muscle.

A modified Golgi method combined with stereoscopy has been used to demonstrate the three-dimensional architecture of the sarcoplasmic reticulum (SR) and the T-system in human skeletal muscle. SR formed a continuous repeating network with a different structure dependent upon the sarcomere position. Intermyofibrillar SR contained three regions: 1) fenestrated collars overlying the M-band region, 2) terminal cisternae overlying the A-I region, and 3) a three-dimensional anastomosed tubular network overlying the Z-band region. Longitudinal and/or transverse SR tubules connected these regions. Subsarcolemmal SR was also composed of three regions: 1) transversely oriented polygonal meshes overlying the M-band, 2) single-layered tubules overlying the Z-band region, and 3) a loose network between the two. In the subsarcolemmal sarcoplasm, where mitochondria were aggregated, SR anastomosed loosely and showed nonfenestrated cisternae beneath the plasma membrane. The T-system was composed of transversely oriented networks overlying the A-I region with occasional longitudinal tubules connecting these networks.

Adolescent↗
PubMed1988

Architecture and structure of canine veins with special reference to confluences.

The occurrence of cell-infiltrated intimal lesions at the confluence of many small tributaries with canine jugular and femoral veins suggested that these areas (confluences) might 1) differ structurally from the rest of the receiving vein and 2) serve as initiation sites for thrombi. To explore these possibilities, the number of tributaries was determined by careful blunt dissection, and the architecture of confluences was studied by light and scanning and transmission electron microscopy. In addition to confluences formed by a named tributary (omobrachial), canine jugular veins averaged 11 confluences formed with small (0.2 to 2.5 mm diameter) unnamed tributaries that had not been previously described. Femoral veins averaged eight confluences of which four were formed with small unnamed tributaries. Double-leafed valves were found at 90% of jugular and 76% of femoral vein confluences. Previously such valves were described only at the confluence of superficial with deep leg veins. Corrosion casts of iliac, saphenous, azygous, costocervical, and maxillary veins as well as cranial and caudal vena cava demonstrated a similar pattern of tributaries and valves. The three structures (receiving vein, tributary, valves) that formed the confluence differed, necessitating considerable modification as they approached the area of fusion. Jugular and femoral vein walls contained 5 to 10 layers of smooth muscle, abundant collagen, and a small amount of elastin. Tributary walls contained 0 to 2 discontinuous smooth muscle cell layers, limited collagen, and no elastin. As receiving veins approached a confluence, the thickness decreased by 15 to 77% except at valve attachment sites, which were thickened. A cluster of smooth muscle cells formed the junction of valve leaflets with vein. Endothelium was continuous over the luminal surface of all three structures. Calculations showed that these small-valved tributaries make only a small contribution to venous return. On the other hand, there is considerable information to support the concept that local attenuation of the vein wall would lead to localized vessel dilation, resulting in rupture of the endothelium and basement membrane.

Animals↗
PubMed1995

Fibrous architecture of the dorsal aponeurosis of the thumb.

BACKGROUND: The extensor apparatus of the thumb displays obvious structural variations in its proximo-distal expanse. Its associated tissue comes in close relation to the dorsal aponeurosis that have varying topographical relationships to the extensor apparatus of the thumb. This region is especially important as the location of pathological and repair processes. METHODS: In this anatomical study using a modified embedding technique a histological description of the fibrous architecture of the dorsal aponeurosis and the peritendinous connective tissue body of the thumb is presented. RESULTS: The dorsal connective tissue of the thumb forms different layers of collagen lamellae as a peritendinous system around the tendons of the long and short extensor tendons of the thumb. This peritendinous laminar system as the main part of the dorsal aponeurosis is connected with both the capsular and the retinacular ligaments of the thumb. CONCLUSIONS: It will be shown that the structural variations of the dorsal aponeurosis and peritendinous connective tissue are an expression of different topographical zones of stress along the lines of a balanced musculofibrous stabilization of the interphalangeal joint of the thumb. The expansions in the peritendinous intercellular space act as defined gliding spaces or clefts of the extensor apparatus.

Aged↗
PubMed2001

Microvascular architecture of the rat choroid: corrosion cast study.

This study presents the details of the microvasculature of the rat choroid visualized by scanning electron microscopy of vascular corrosion casts. Wistar Kyoto rats were anesthetized with intraperitoneal sodium pentobarbital. The vascular system was perfused with heparinized saline, and Mercox resin was injected into the cannulated carotid arteries. After polymerization of the resin, the vascular casts were macerated with potassium hydroxide, washed with water, and freeze dried. The casts were examined with a Hitachi S-2360N scanning electron microscope (SEM). Corrosion casts of the entire choroidal vasculature revealed that the two long posterior ciliary arteries supplied the entire uveal vasculature. In the posterior choroid, these arteries formed five to seven branches on each side supplying the adjacent choriocapillaris. No interarterial or arteriovenous anastomoses were seen. The choriocapillaris appeared as a nonhomogeneous and nonlobular monolayer capillary network, consisting of dense honeycomb and irregular patterns. There are two distinct venous systems in the rat choroid. The venous blood from the central region, peripapillary choroid, and sometimes the optic nerve head drain into the posterior ciliary vein. The venous blood from the iris, ciliary body, anterior choroid, and half of the posterior choroid drain into the vortex veins. Corrosion casts and the SEM have shown details of the choroidal vascular architecture. These three-dimensional observations indicate that the rat choroidal vasculature has different features from those of humans and other primates. Despite these interspecies differences, the establishment of a thorough baseline concept of choroidal vasculature should permit additional studies of the choroidal pathology and enable the proper interpretation of results from rat experimental models for extrapolation to humans.

Animals↗
PubMed2003

Effect of lacunocanalicular architecture on hydraulic conductance in bone tissue: implications for bone health and evolution.

Bone tissue health depends largely on efficient fluid and solute transport between the blood supply and cells that are the living component of the tissue. We hypothesized that the lacunocanalicular hydraulic network, which is defined by the pericellular fluid space that is common to all bone tissue, is optimized to transport fluid and solutes between the blood supply and bone cells. An analytical study was carried out to evaluate the effect of osteonal architecture, including the osteon diameter, number of annular lamellar regions, and number and length of canalicular channels, on fluid transport between the blood supply and bone cells. On the basis of this analysis, we conclude that osteon size is limited to the distance over which fluid and solutes can be transported efficiently between the blood supply and cells. This analytic model suggests that hydraulic conductivity is highest in lamellar regions closest to the Haversian canal (HC) and decreases with increasing distance from the blood supply, reaching a plateau after the fifth lamella (169 micro m radius). Furthermore, an increase in the diameter of the HC, or a decrease in the length of canaliculi, reduces the hydraulic conductivity within the lacunocanalicular network. Applying the principle of minimal expenditure of energy to this analysis, the path distance comprising five or six lamellar regions represents an effective limit for fluid and solute transport between the blood supply and cells; beyond this threshold, hydraulic resistance in the network increases and additional energy expenditure is necessary for further transportation. This suggests that transport is optimized to meet metabolic demands concomitant with a minimal expenditure of energy. This fundamental new insight into bone structure and physiology may provide a new basis of understanding for tissue engineering, bone physiology in health and disease, and evolutionary biology.

Animals↗