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At least 559 records · Page 31Linked to original sources
PubMed1993

Optic nerve sheath fenestration for treatment of progressive ischemic optic neuropathy. Results in 26 patients.

Optic nerve sheath fenestration was performed in 26 eyes for treatment of the progressive type of common (nonarteritic) anterior ischemic optic neuropathy. During a mean follow-up period of 21 weeks (range, 6 to 52 weeks), results were as follows: visual acuity increased by two or more lines on the Snellen chart in 7 eyes; visual acuity decreased by two or more lines in four eyes; some regression of visual field defects occurred in six eyes, including two eyes in which acuity also improved. These results, attributed to surgical decompression, do not exceed the spontaneous recovery rates reported in the literature pertaining to nonarteritic anterior ischemic optic neuropathy and fail to substantiate the sanguine visual outcome in recently reported series of patients undergoing optic nerve sheath decompression.

Aged↗
PubMed1993

Optic nerve sheath fenestration through a lateral canthotomy incision.

Optic nerve sheath fenestration is an increasingly useful surgical technique for relief of visual loss due to a number of optic disc pathologic conditions. To date, surgeons have employed either a medial approach with disinsertion of the medial rectus muscle or a lateral approach with removal of the lateral orbital rim to gain access to the retrobulbar optic nerve. We report herein a technique for approaching the optic nerve through a lateral canthotomy incision that does not require removal of bone or disinsertion of an extraocular muscle. It has been used to provide ready surgical exposure of the optic nerve in 17 eyes of 14 patients. This technique combines the advantages of lateral exposure of the optic nerve with an ease of operation similar to that of the medial approach.

Chronic Disease↗
PubMed1977

The fenestrated collar of mammalian cardiac sarcoplasmic reticulum: a freeze-fracture study.

Freeze-fracture studies of papillary muscles from cat, rabbit and dog reveal the presence of a fenestrated collar of the sarcoplasmic reticulum (SR) in the region of the M band. This membrane specialization is structurally similar to that observed previously in skeletal muscle. This report includes mammalian cardiac muscle on the list of those muscles containing this SR membrane structure.

Animals↗
PubMed1977

Fenestrations in regenerating skeletal muscle capillaries.

A new observation of fenestrae with diaphragms in the endothelial wall of regenerating skeletal muscle capillaries is described in seven-day-old wounds of the cremaster muscle of adult male guinea pigs. The fenestrations were 44 nm in diameter and contained diaphragms with a central dense structure. These findings suggest an additional route for physiological exchange mechanisms in wound capillaries.

Animals↗
PubMed1985

Restriction to endogenous plasma proteins by a fenestrated capillary endothelium: an ultrastructural immunocytochemical study of the choriocapillary endothelium.

The choriocapillaris is a fenestrated capillary bed in the eye that restricts the egress of exogenous tracer molecules with Einstein-Stokes radii (ESR) greater than or equal to 3.2 nm. The present study examined the permeability of its endothelium to the endogenous plasma proteins albumin (ESR, 3.5 nm) and IgG (ESR, 5.5 nm) using ultrastructural immunocytochemistry. Reaction product indicative of the localization of albumin and IgG (using Fab-HRP conjugates) was high in the capillary lumen. In contrast, neither protein was localized extravascularly in Bruch's membrane, in endothelial vesicles, or in endothelial channels. The restriction was evident at the luminal side of the diaphragms spanning fenestrae, vesicles, and channels, and at the luminal front of cell junctions. In marked comparison, high levels of reaction product were localized in the extravascular space surrounding mucosal capillaries in the ileo-jejunum. Observations of tissue subjected to postembedment staining using a protein A-gold method were similar. These findings demonstrate for the first time the restriction of endogenous plasma proteins by a capillary endothelium identical in morphology to that of other vascular beds proven to be permeable.

Animals↗
PubMed2004

Membrane-transport systems in the fenestrated capillaries of the area postrema in rat and calf.

The capillaries of the area postrema (AP) lack the morphological peculiarity of the blood-brain barrier (BBB), and the AP neurons are considered located outside the BBB. Using the immunofluorescent method, we have investigated the expression of membrane transport systems that are instrumental to the BBB function, such as caveolin-1, -2, P-glycoprotein, and glut-4, in the capillary endothelium of the rat and calf AP. The expression of these molecules was verified after fibronectin immunostaining of the microvessels. Both in the rat and calf, caveolin-1, -2, and P-glycoprotein were expressed in the AP capillaries. A quantitative analysis revealed that the proportion of the capillary profiles expressing these transport systems was very close to 100% of the fibronectin immunolabelled profiles. On the contrary, none of the AP capillaries showed glut-4 immunoreactivity. The present investigation demonstrates that the endothelial layer of the AP capillaries, in spite of the paracellular passage of polar molecules through the leaky tight junctions and fenestrations, could be an active interface which is able to control the entry of a wide range of blood-borne compounds into the brain by means of specific mechanisms, including an efflux pump.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2006

T lymphocytes interact with hepatocytes through fenestrations in murine liver sinusoidal endothelial cells.

The liver has an established ability to induce tolerance. Recent evidence indicates that this unique property might be related to its distinctive architecture allowing T cells to be activated in situ independently of lymphoid tissues. Unlike lymph node-activated T cells, liver-activated T cells are short-lived, a mechanism that might contribute to the "liver tolerance effect." Although the potential role of hepatocytes as tolerogenic antigen-presenting cells has been demonstrated, the question as to whether these cells are able to interact with CD8(+) T cells in physiological settings remains controversial. Contradicting the immunological dogma stating that naïve T lymphocytes are prevented from interacting with parenchymal cells within non-lymphoid organs by an impenetrable endothelial barrier, we show here that the unique morphology of the liver sinusoidal endothelial cell (LSEC) permits interactions between lymphocytes and hepatocytes. Using electron microscopy, we demonstrate that liver resident lymphocytes as well as circulating naïve CD8(+) T cells make direct contact with hepatocytes through cytoplasmic extensions penetrating the endothelial fenestrations that perforate the LSECs. Furthermore, the expression of molecules required for primary T cell activation, MHC class I and ICAM-1, is polarized on hepatocytes to the perisinusoidal cell membrane, thus maximizing the opportunity for interactions with circulating lymphocytes. In conclusion, this study has identified, at the ultrastructural level, a unique type of interaction between naïve T lymphocytes and liver parenchymal cells in vivo. These results hold implications for the pathogenesis of viral hepatitis in which hepatocytes may represent the main antigen-presenting cell, and for the development of immune tolerance as lymphocytes pass through the liver.

Animals↗
PubMed1994

An analysis of the interaction between interstitial plasma protein, interstitial flow, and fenestral filtration and its application to synovium.

An analysis of the interstitial flow of a protein solution is presented, based on physical interactions with extracellular matrix biopolymers. Previous models were extended by incorporation of three features--(a) interstitial osmotic reflection coefficients and attendant partial molecular sieving, (b) the effect of solute exclusion on apparent intramatrix fluid viscosity, and (c) the effect of discrete capillary porosity on near-pore oncotic and hydraulic gradients. The principles were applied to a distributed, finite difference model of the synovial lining and its fenestrated capillaries. Numerical solutions were used to assess the significance of some of the factors involved and predictions were compared with experimental measurements of the transsynovial flow of albumin solutions in the steady state. The following physiologically important points emerged. (i) Steric exclusion of protein reduces the effective interstitial fluid viscosity and creates nonzero interstitial reflection coefficients, which impose a slight nonuniformity of interstitial plasma protein distribution. Together these two effects produce nonintuitive deviation of interstitial flow from Darcy's law when interstitial protein concentration is increased experimentally. (ii) Flow across fenestrae with high reflection coefficients is buffered by steep local gradients in interstitial oncotic and hydraulic pressures immediately outside the fenestrae. Buffering is underestimated by the mean interstitial Starling forces and by treatment of the capillary as if it were uniformly permeable to water. (iii) A bidirectional flow pattern can develop across the synovial lining and can contribute to fluid turnover within the joint cavity.

Animals↗
PubMed1976

Fenestrated blood capillaries in rat cranio-spinal sensory ganglia.

Several fenestrated capillaries were seen in the endoneurium of trigeminal and dorsal root ganglia from two young adult albino rats treated with tetraethylthiuram disulfide. The finding is regarded as normal, although the possibility exists that intoxication with tetraethylthiuram disulfide may have enhanced the intensity and/or rate of this cytologic specialization of some isolated endothelial cells.

Animals↗
PubMed1975

Fenestrated blood capillaries and lymphatic capillaries in rat skeletal muscle.

Capillary fenestrae occur in one of about 60 cross-sectioned blood capillaries in normal adult rat skeletal muscles. The fenestrae occur singly or in groups. Fenestrated capillaries are found close to muscle fibers as well as in the perimysial and perineurial connective tissue. Small numbers of lymphatic capillaries are also present, mostly in the perimysial connective tissue.

Animals↗
PubMed1990

Dandy-Walker syndrome: posterior fossa craniectomy and cyst fenestration after several shunt revisions.

Ventriculoperitoneal or cyst-peritoneal shunts are the usual treatment for children with Dandy-Walker syndrome. A combined ventricular and cyst shunt is often necessary and, in some cases, multiple revisions have to be done. Two patients with this syndrome were treated with posterior fossa exploration and cyst fenestration after several shunt revisions. The procedure was well tolerated with good results in both cases. The patients' data and preliminary results are presented here.

Brain Diseases↗
PubMedDate not supplied

Fenestration in the management of polycystic liver disease.

Thirteen patients with symptomatic polycystic liver disease who were selected for fenestration were reviewed. The main preoperative complaints that related to polycystic liver disease were severe abdominal pain, respiratory distress, clinical ascites, or leg edema. All symptoms disappeared after operation, and the number and size of the cysts were smaller. Five patients developed transient but massive ascites during the postoperative period, and long-term follow-up demonstrated a moderate recurrence of hepatomegaly in two patients. These postoperative complications and failures appeared to be at least partly related to a more extensive evolution of the disease in the patients in whom it developed.

Adult↗
PubMed1983

Fenestration and duplicate origin of the left vertebral artery in angiography. Report of three cases.

Three cases are shown; 2 of angiographically proven distal fenestration of the left vertebral artery and one of duplicate origin. Both anomalies are classified as of inhibitory type. Their incidence in the literature is reviewed. Underlined is the fact that variations of this nature frequently occur in combination with other inhibitory malformations particularly in the vascular and skeletal systems.

Adult↗
PubMed1985

On the occurrence of the fenestrated vessels in Wallerian degeneration of the peripheral nerve.

Ultrastructural studies were made on the distal segments of the mouse phrenic nerve after crush injury. In the control, endoneurium contained only unfenestrated capillaries. In the experiment, from day 2 to day 6, endoneurial capillaries occasionally showed fenestrations with the attenuation of its cytoplasm. At this stage, axonal degeneration and myelin breakdown became evident showing early stage of Wallerian degeneration. In addition, detachment of the neighboring endothelial cells concomitant with the invasion of macrophage was also observed. These findings were previously unobserved changes of the endoneurial endothelium in Wallerian degeneration. The significance of the early occurrence of fenestrae was discussed briefly.

Animals↗
PubMed1979

Fenestrated blood vessels in human skeletal muscle.

In a fine structural study of 32 skeletal muscle biopsies, rare examples of fenestrated blood vessels (FV) were found in three cases. In view of similar observations reported in a case of Duchenne muscular dystrophy, it is suggested that FV albeit rare may occur in skeletal muscle at least under pathologic conditions. These aberrant FV may be derived from adjacent dermis and/or epineurium which are known to contain occasional FV. Alternatively, the occurrence of fenestrae may reflect a nonspecific alteration in pre-existing continuous endothelium. The significance, if any, of their presence in skeletal muscle is unknown.

Adult↗
PubMed1977

Dosimetric studies in the radiological examination of the hips in young infants with a special fenestration method of gonad protection.

A special lead shield of 1,5 mm Pb, with a fenestration was used for gonad protection during X-Ray of the hips for detection of dysplasia. The window allows the delineation of all parts of the skeleton required to make a correct diagnosis and check the standardized position of the pelvis, while all other parts, especially the gonads are safely shielded. The scattered radiation for the testes was further reduced by a trough-shaped lead shield behind the scrotum. The effectiveness of this gonad protection was measured by direct dosimetric studies on the infant with LiF and CaF2: Dy dosimeters at different adjustments of the X-ray generator and with medium and ultra high speed screen-film combinations.

Female↗
PubMed1991

Anomalies of the P1 segment of the posterior cerebral artery: early bifurcation or duplication, fenestration, common trunk with the superior cerebellar artery.

In a series of anatomical dissections on 100 fixed human brains, 3% of anomalies of the precommunicating segment of the posterior cerebral artery (P1) were found, among which a case of duplication of the P1 segment. This finding is very unusual and it is much rarer than the many other anatomical patterns reported in the circle of Willis. It is to be considered a very early bifurcation, as reported at the middle cerebral artery level. Another two unusual anatomical patterns were found. One was a large fenestration of the P1 segment, which is rather frequent in the vertebrobasilar system. The other was a bilateral common trunk between the posterior cerebral artery and the superior cerebellar artery, which represents a rare anatomical variation. The existence of such "anomalies" can be explained by the embryological development of the region. Their pathogenic and neurosurgical implications are discussed in the light of the literature.

Arteries↗