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PubMed2004

Mechanical adaptations of cleavers (Galium aparine).

BACKGROUND AND AIMS: Cleavers (Galium aparine) is a fast-growing herbaceous annual with a semi-self-supporting, scrambling-ascending growth habit. Mature plants often use upright species for support. It is common in hedgerows and on waste ground. This study aims to characterize the mechanical behaviour of the stem and roots of cleavers and relate this to the arrangement of structural tissue, the net microfibrillar orientations in the cell walls, and plant growth habit. METHODS: The morphology and mechanics of mature cleavers was investigated using plants grown in pots and ones collected from the grounds at the University of Lincoln, Lincoln, UK. Tensile tests were carried out on the stem and the basal section of the first-order lateral roots. The net orientation of cellulose microfibrils in the cell walls was investigated using polarized light microscopy. KEY RESULTS: Results show that the basal regions of the stem and first-order lateral roots were highly extensible. Breaking strains of 24 +/- 7% were recorded for the stem base and 28 +/- 6% for the roots. Anatomical observations showed that the lower stem (base + 100 mm) was circular in cross-section with a solid central core of vascular tissue, whereas further up the stem the transverse section showed a typical four-angled shape with a ring-like arrangement of vascular tissue and sclerenchyma bundles in the corners. The net orientation of wall microfibrils in the secondary xylem diverges from the longitudinal by between 8 and 9 degrees . CONCLUSIONS: The basal region of the stem of cleavers is highly extensible, but the mechanism by which the stem is able to withstand such high breaking strains is unclear; reorientation of the cellulose fibrils in the stem along the axis of loading is not thought to be responsible.

Adaptation, Physiological↗
PubMed1996

Cell-Wall Polysaccharides of Developing Flax Plants.

Flax (Linum usitatissimum L.) fibers originate from procambial cells of the protophloem and develop in cortical bundles that encircle the vascular cylinder. We determined the polysaccharide composition of the cell walls from various organs of the developing flax plant, from fiber-rich strips peeled from the stem, and from the xylem. Ammonium oxalate-soluble polysaccharides from all tissues contained 5-linked arabinans with low degrees of branching, rhamnogalacturonans, and polygalacturonic acid. The fiber-rich peels contained, in addition, substantial amounts of a buffer-soluble, 4-linked galactan branched at the 0-2 and 0-3 positions with nonreducing terminal-galactosyl units. The cross-linking glycans from all tissues were (fucogalacto)xyloglucan, typical of type-I cell walls, xylans containing (1->)-[beta]-D-xylosyl units branched exclusively at the xylosyl O-2 with t-(4-O-methyl)-glucosyluronic acid units, and (galacto)glucomannans. Tissues containing predominantly primary cell wall contained a larger proportion of xyloglucan. The xylem cells were composed of about 60% 4-xylans, 32% cellulose, and small amounts of pectin and the other cross-linking polysaccharides. The noncellulosic polysaccharides of flax exhibit an uncommonly low degree of branching compared to similar polysaccharides from other flowering plants. Although the relative abundance of the various noncellulosic polysaccharides varies widely among the different cell types, the linkage structure and degree of branching of several of the noncellulosic polysaccharides are invariant.

Journal Article↗
PubMed1980

[The hemodynamics of the uveal and retinal circulation and its clinical diagnosis (author's transl)].

Diagnosis and therapy of retinal and uveal circulatory disorders should be based mainly on two pathophysiologic principles: (1) an autoregulation is effective in the retinal circulation only but absent in the choroidal circulation and (2) circulatory disorders may be caused not only be a reduced but also by an increased blood flow. The clinical evaluation of an individual retinal circulatory disorder depends on the interpretation of the dynamics of visual disturbances, detection of vascular type or fiber bundle defects in the visual field, repeated estimation of blood flow velocity by direct ophthalmoscopy or fluorescence angiography, and detection of specific fundus signs such as focal ischemia (cotton wool spots) or development of a collateral circulation and true neovascularization. For the indirect assessment of disturbances of the choroidal circulation certain subjective symptoms, alterations of the pigment epithelium, and edema and focal defects of the choriocapillaries are of importance. The stereobiomicroscopy of the fundus with a slitlamp and fluorescence angiographic studies of the sectorial distribution of the choroidal filling are valuable diagnostic aids.

Choroid↗
PubMed2005

Ectopic development of skeletal muscle induced by subcutaneous transplant of rat satellite cells.

The present study analyzes the ectopic development of the rat skeletal muscle originated from transplanted satellite cells. Satellite cells (10(6) cells) obtained from hindlimb muscles of newborn female 2BAW Wistar rats were injected subcutaneously into the dorsal area of adult male rats. After 3, 7, and 14 days, the transplanted tissues (N = 4-5) were processed for histochemical analysis of peripheral nerves, inactive X-chromosome and acetylcholinesterase. Nicotinic acetylcholine receptors (nAChRs) were also labeled with tetramethylrhodamine-labeled alpha-bungarotoxin. The development of ectopic muscles was successful in 86% of the implantation sites. By day 3, the transplanted cells were organized as multinucleated fibers containing multiple clusters of nAChRs (N = 2-4), resembling those from non-innervated cultured skeletal muscle fibers. After 7 days, the transplanted cells appeared as a highly vascularized tissue formed by bundles of fibers containing peripheral nuclei. The presence of X chromatin body indicated that subcutaneously developed fibers originated from female donor satellite cells. Differently from the extensor digitorum longus muscle of adult male rat (87.9 +/- 1.0 microm; N = 213), the diameter of ectopic fibers (59.1 microm; N = 213) did not obey a Gaussian distribution and had a higher coefficient of variation. After 7 and 14 days, the organization of the nAChR clusters was similar to that of clusters from adult innervated extensor digitorum longus muscle. These findings indicate the histocompatibility of rats from 2BAW colony and that satellite cells transplanted into the subcutaneous space of adult animals are able to develop and fuse to form differentiated skeletal muscle fibers.

Acetylcholinesterase↗
PubMed2001

Kaposi's sarcoma occurring during short-term dialysis: report of two cases.

Kaposi's sarcoma (KS) appears to develop in association with kidney transplantation, but unlikely with dialysis. We report two cases of classic KS that occurred in patients receiving short-term (less than 3 yr) dialysis. They have been suffering from chronic renal failure due to tuberculosis and diabetes mellitus, respectively. Several to multiple, reddened-violaceous patches, plaques and nodules were found on the hand and the lower extremities. Laboratory studies showed no evidence suggesting immunosuppressed state and there was no history of taking immunosuppressive agents. The biopsies of the two cases revealed proliferation of spindle-shaped cells focally arranged in bundles and multiple dilated vascular spaces outlined by an attenuated endothelium with intravascular and extravasated erythrocytes. The specimens expressed positivity with CD34 antigen. Human herpesvirus 8 (Kaposi's sarcoma-associated herpesvirus) was detected in one case by polymerase chain reaction method.

Aged↗
PubMed2000

Development of the gametophytes, flower, and floral vasculature in Dichorisandra thyrsiflora (Commelinaceae).

The flowers of Dichorisandra thyrsiflora (Commelinaceae) are monosymmetric and composed of three sepals, three petals, six stamens, and three connate carpels. The anthers are poricidal and possess a wall of five cell layers (tapetum included). This type of anther wall, not previously observed in the Commelinaceae, is developmentally derived from the monocotyledonous type via an additional periclinal division and the persistence of the middle layers through anther dehiscence. Secondary endothecial thickenings develop in the cells of the two middle layers only. The tapetum is periplasmodial and contains raphides. Microsporogenesis is successive and yields both decussate and isobilateral tetrads. Pollen is shed as single binucleate grains. The gynoecium is differentiated into a globose ovary, hollow elongate style, and trilobed papillate stigma. Each locule contains six to eight hemianatropous to slightly campylotropous crassinucellar ovules with axile (submarginal) placentation. The ovules are bitegmic with a slightly zig-zag micropyle. Megagametophyte development is of the Polygonum type. The mature megagametophyte consists of an egg apparatus and fusion nucleus; the antipodals having degenerated. The floral vasculature is organized into an outer and inner system of bundles in the pedicel. The outer system becomes ventral carpellary bundles. All other floral vascular traces originate from the inner system.

Journal Article↗
PubMed2001

Contributions to the debate on water transport.

The useful criticisms of my theory of water transport by Comstock (American Journal of Botany 86: 1077-1081) and by Stiller and Sperry (American Journal of Botany 86: 1082-1086) are acknowledged and reviewed. I make the following responses. (1) Tensile stresses to contain tissue pressure are kept within modest limits by the organization of vascular tissues into cylindrical bundles with small ratios of radius/boundary thickness. (2) The balance of pressures within tissues of a nontranspiring leaf is best understood by treating it as a single compartment containing several pressure-generating engines whose resultant is the pressure throughout the compartment. An error in the published notional balances for a transpiring leaf is corrected. (3) The argument against a valve in the transpiring leaf, which allows water out but not in, is not convincing. (4) The "robust and extremely consistent" cohesion theory gains this status by neglecting large bodies of experimental fact, once well known to plant physiologists. (5) The demonstration that living cells are not involved in the refilling of embolisms in birch stems is welcomed as an important advance. However, the major questions remain unresolved. (6) Proof is still needed that embolisms in vessels are not refilled by the collapse of gas bubbles under small positive pressures during conductance measurement. (7) The survival of unbroken water threads in vessels under centrifugal stress has still not been demonstrated. (8) Both questions 6 and 7 can be easily answered by direct observation of gas/liquid volumes in frozen stems in the cryo-scanning electron microscope.

Journal Article↗
PubMed1992

[Primary open angle glaucoma and low tension glaucoma--pathogenesis and mechanism of optic nerve damage].

The etiology, pathogenesis and mechanism of optic nerve damage in primary open angle glaucoma (POAG) and low tension glaucoma (LTG) were investigated by experimental glaucoma in monkey and by follow-up studies of many patients over 15 years, by pathohistological and immunohistochemical analysis. 1) LTG was proved to be a real glaucoma, showing pressure-dependent optic nerve damage. The pathological entity was a primary weakness of the lamina cribrosa (LC), and therefore even normal pressure could deform the LC. Due to backward distortion of LC the channels were disarranged and twisted, inducing mechanical optic nerve damage. There was no active vascular damage or vascular constriction at the site of the optic nerve damage. The filling defects of the advanced glaucomatous optic disc were not the cause of optic nerve damage, but the result of regressive vascular change after axon bundle loss. Splinter hemorrhage of the optic disc might be the result of the same process. 2) The weakness of LC might be induced by the abnormal metabolism of the extracellular matrix of the LC. 3) To arrest the progressive optic nerve damage in LTG, the intraocular pressure (IOP) should be maintained under 12, or ideally, 10 mmHg. 4) The optic nerve damage in POAG was not only pressure-dependent, but also dependent on the weakness of the LC, as in the case of LTG. In the early stage the IOP should be under 19 mmHg, in the advanced stage under 14 mmHg in order to arrest progression for over 15 years. 5) In advanced experimental glaucoma of monkeys, the LC showed reduction of elastin, fragmentation of collagen, and change of proteoglycans. 6) As in the LC, the trabecular meshwork also showed abnormal metabolism and abnormal deposits on the extracellular matrix in POAG, and LTG as well. 7) POAG and LTG might belong to the same family in which common abnormal metabolism of LC and trabecular meshwork induce various clinical features.

Adolescent↗
PubMed1990

Clinical and ultrastructural studies of Romberg's hemifacial atrophy.

Romberg's disease is an uncommon and poorly understood condition manifested by progressive hemifacial atrophy of skin, soft tissue, and bone. In order to better define the natural history and anatomic variation of this disorder, we evaluated 41 patients by history, physical examination, and facial radiographs. Light microscopic studies were performed on tissue from 19 patients, and ultrastructural analysis was performed on specimens from 6 patients. The average age at inception of the disease was 8.8 years. Atrophy, within one or more trigeminal nerve dermatomes, progressed at a variable rate (mean period of active tissue dissolution = 8.9 +/- 6 years). In 26 patients with skeletal involvement, the mean age of onset was 5.4 years, versus 15.4 years for 15 patients without skeletal involvement, a statistically significant difference (p less than 0.01). However, there was no correlation between the severity of soft-tissue deformity and the age of onset. Electron microscopy demonstrated lymphocytic infiltrates in neurovascular bundles and abnormalities of vascular endothelium and basement membranes. We hypothesize that the pathogenesis of Romberg's disease involves chronic cell-mediated vascular injury and incomplete endothelial regeneration along branches of the trigeminal nerve (lymphocytic neurovasculitis).

Adult↗
PubMed1995

NADPH-diaphorase-containing cerebrovascular nerve fibres and their possible origin in the pig.

NADPH-diaphorase histochemical technique was applied to demonstrate the catalytic activity of nitric oxide synthase (NOS) in the nerve fibers supplying some porcine cerebral blood vessels, as well as in ganglia thought to be their possible sites of origin. Five sexually mature Large With Polish race sows were used. The following blood vessels and their branches were studied: the basal cerebral artery, medial cerebral artery, arteries of the circle of Wills as well as arteries located in the arachnoidea. The activity of NADPH-d was visualised in whole-mount preparations from the above listed blood vessels. The presence of NADPH-d was additionally studied in the ganglia of trigeminal nerves, the sensory ganglia of vagus nerves, the pterygopalatine and cranial cervical ganglia. NADPH-d activity was found in nerve fibres supplying all the studied arteries. Larger blood vessels, the basal cerebral artery, medial cerebral artery and arteries of the circle of Wills possessed very dense NADPH-d-positive nerve plexuses while arachnoidal arteries were poorly innervated by only single nerves. The vascular nerve fibers formed bundles varying in thickness, from very thick bundles often interchanging nerve fibers to quite thin fascicles. Thick bundles were absent from the walls of medium sized vessels and small meningeal arteries where only smaller fascicles or single fibres occurred. NADPH-d-positive neurons and nerve fibres were found in all the ganglia investigated. However, pronounced differences in the number of the positive nerve structures were observed between the ganglia. In the pterygopalatine, trigeminal and sensory ganglia of the vagal nerve the vast majority of neurons were NADPH-d-positive. Numerous NADPH-d-positive nerve fibers occurred within the pterygopalatine and trigeminal ganglion while sensory ganglia of the vagal nerve comprised smaller number of fibres. Small numbers of the neurons and moderate numbers of the nerve fibres occurred in the cranial cervical ganglion. The intensity of NADPH-d reaction in the endothelium was constant independent of the size of the vessels studied.

Animals↗
PubMed1994

Reconstruction of rabbit anterior cruciate ligament using the autogenous patellar tendon.

We excised the anterior cruciate ligament and reconstructed it with the patellar tendon autograft in 43 rabbits. The animals were sacrificed from 2 to 48 weeks after reconstruction. Gross and histological examinations of 43 knees were performed to investigate the characteristics of the maturation process of the grafts. The reconstructed ligaments were found to be lusterless white and covered with synovial tissue throughout the study. At 24 weeks, the grafts were remodeled with wider collagen bundles and with less vascularity after degenerative processes. There was graft relaxation, a response to the initial tension, postoperatively over the entire 24 weeks. This suggests that postoperative management should be carefully performed during graft maturation.

Animals↗
PubMedDate not supplied

A filter device for the prevention of both heparin- and protamine-induced complications associated with extracorporeal therapy.

When extracorporeal blood circulation (ECBC) is used, systemic heparinization is necessary to prevent clotting of the blood in the extracorporeal circuit. However, the high circulating heparin concentration needed often leads to bleeding complications. To avoid these, protamine, a heparin antagonist, is administered at the conclusion of the ECBC procedure to reverse the anticoagulant activity of heparin. Intravenous administration of protamine can cause hypotension and shock. To date, there has been no real alternative to control the bleeding risks associated with systemic use of heparin and the adverse effects resulting from heparin reversal with protamine. A novel approach that might control both the heparin- and the protamine-induced complications is suggested. It consists of placing a blood-compatible filter device containing immobilized protamine (a protamine filter) at the distal end of the ECBC apparatus. The filter removes heparin after heparin serves its anticoagulant purpose in the extracorporeal circuit and before blood is returned to the patient. The filter also allows for an external protamine treatment. Since protamine toxicity results from the direct contact of protamine with cells of the liver, lungs, and other organ tissues, the use of an external protamine treatment would minimize it. Protamine was covalently immobilized onto a cellulosic hollow fiber bundle obtained from a clinically used hemodialyzer. The bundle was accessed to the vascular system of a dog by femoral artery and vein cannulation. In in-vivo experiments the protamine-bound fiber bundle not only removed heparin from the extracorporeal circuit, but also caused no clinically significant hemodynamic change in the animal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adsorption↗
PubMed1977

Tubulo-vascular relationships in the developing kidney.

The postnatal development of the tubulo-vascular relationships in the kidney was studied in 60 rats. The kidney is relatively immature at birth and only the juxtamedullary glomeruli are present. As their loops of Henle develop they grow down into the medulla around the previously developed collecting ducts, forming tubulovascular 'units' around whose periphery the shorter loops of the more peripheral glomeruli grow down. The bundles of vasa recta develop in loose interstitial tissue which lies between the tubulo-vascular units so that the peripheral vessels of the bundles, which are ascending vasa recta, lie in close relationship with the descending short loops of Henle. Thus, the vascular bundles do not form the central axis around which the medullary components develop but rather take up the available space left after the tubulo-vascular units have developed. Development is virtually complete by the fourth week of postnatal life.

Animals↗
PubMed1993

Evidence for a distinct gap-junctional phenotype in ventricular conduction tissues of the developing and mature avian heart.

The gap-junctional proteins connexin43 and connexin42 have been shown to be expressed in the developing and mature avian heart, but their respective spatiotemporal distributions are unknown. In the present study, we have immunolocalized connexin42 in the conduction tissues of the adult avian heart (nonbranching bundle, bundle branches, and Purkinje fibers) and vascular endothelial cells. Connexin43 immunolabeling was confined to vascular smooth muscle. A novel microwave-based method was used to label connexin42 and connexin43 in the same tissue section. Neither connexin42 nor connexin43 was immunolocalized in working myocardium, atrioventricular node, and atrioventricular ring tissue of the bird heart. Although connexin42 first appeared in periarterial conduction myocytes and vascular endothelium at 9-10 embryonic days, the central conduction tissues, including the nonbranching bundle and proximal branches, remained immunonegative for connexin42 up until hatching (approximately 20 embryonic days). During the early postnatal period (1-14 days), connexin42 immunolabeling progressively spread up the bundle branches toward the nonbranching bundle. Connexin42 appeared uniformly distributed along the left bundle branch by 14 postnatal days. The distribution and spread of connexin42 immunoreactivity suggest that the emergence of specialized junctional contacts along ventricular fascicles occurs relatively late in heart development and coincides with the emergence of the chick from incubation within the egg.

Age Factors↗
PubMed1993

Vascularized megaflaps.

In the early 1980s Japanese surgeons introduced very long free flaps based on two vascular pedicles from the thoracodorsal and groin territories. Such flaps, vascularized through two pedicles, may be called megaflaps. One or both bundles may be anastomosed as necessary to vascularize the flap. Anatomical studies and clinical experience point to new donor sites for such megaflaps.

Adult↗
PubMed1990

Microvascular anatomy of the radioscapholunate ligament of the wrist.

The microvascular circulation and basic structural features of the radioscapholunate ligament of the wrist were studied in six fresh cadaver specimens by injection and clearing techniques. A rich vascular supply was found to originate from vessels that perforate the palmar capsule and enter the synovium that surrounds the ligament. By way of branches from the synovium, the radioscapholunate ligament and most of the scapholunate interosseous ligament receive an abundant blood supply. No contributions are derived from the bony attachments. Observation under light microscopy revealed a delicate, well-vascularized ligament consisting of regular collagen bundles. No elastic fibers were observed. This study indicates that the radioscapholunate ligament has a vascular supply that may be sufficient for healing by known methods.

Humans↗
PubMed2003

Control of Ascorbate Peroxidase 2 expression by hydrogen peroxide and leaf water status during excess light stress reveals a functional organisation of Arabidopsis leaves.

In Arabidopsis leaves, high light stress induces rapid expression of a gene encoding a cytosolic ascorbate peroxidase (APX2), whose expression is restricted to bundle sheath cells of the vascular tissue. Imaging of chlorophyll fluorescence and the production of reactive oxygen species (ROS) indicated that APX2 expression followed a localised increase in hydrogen peroxide (H2O2) resulting from photosynthetic electron transport in the bundle sheath cells. Furthermore, leaf transpiration rate also increased prior to APX2 expression, suggesting that water status may also be involved in the signalling pathway. Abscisic acid stimulated APX2 expression. Exposure of ABA-insensitive mutants (abi1-1, abi2-1) to excess light resulted in reduced levels of APX2 expression and confirmed a role for ABA in the signalling pathway. ABA appears to augment the role of H2O2 in initiating APX2 expression. This regulation of APX2 may reflect a functional organisation of the leaf to resolve two conflicting physiological requirements of protecting the sites of primary photosynthesis from ROS and, at the same time, stimulating ROS accumulation to signal responses to changes in the light environment.

Abscisic Acid↗