Deep Capillary Research Articles

Two dimensional mapping of the perfusion of the retina and optic nerve head.

To present a new non-invasive method of performing a high definition topography of perfused vessels of the retina and the optic nerve head with simultaneous evaluation of blood flow. By a combination of a laser Doppler flowmeter with a scanning laser system the perfusion of the retina and the optic nerve head is visualised. The principles of measuring blood flow by laser Doppler flowmetry are based on the optical Doppler effect: laser light scattered by a moving particle is shifted in frequency by an amount delta f. Our data acquisition and evaluation system is a modified laser scanning tomograph. The technical data are retinal area of measurement 2.7 mm x 0.7 mm, 10 degrees field with 256 points x 64 lines, measurement accuracy 10 microns, wavelength 670 nm and 790 nm, light power 100 microW and 200 microW, data acquisition time 2.048 s. Every line is scanned 128 times by a line sampling rate of 4000 Hz. By performing a discrete fast Fourier transformation over 128 intensities of each retinal point the laser Doppler shift is calculated for each retinal point. With these data a two dimensional map with 256 x 64 points of the retinal perfusion is created. The brightness of the pixel is coded by the value of the Doppler shift. Offline capillary blood flow is estimated in arbitrary units according to the theory of laser Doppler flowmetry in every region of interest of the perfusion picture. We estimated the reliability and the validity of the method. Retinal blood flow was measured by scanning laser Doppler flowmetry (SLDF) while varying intraocular pressure by a suction cup of three healthy volunteers. Measurements of retinal blood flow performed in 47 eyes by the presented method (SLDF) were correlated with data gained by a commercially available laser Doppler flowmeter. Perfusion pictures of the superficial retinal layer and of deep prelaminar layers in the optic nerve head are presented. The reliability coefficients r1 of 'flow', 'volume', and 'velocity' were 0.84, 0.85, and 0.84 respectively. We found a significant linear relation between SLDF flow and the ocular perfusion pressure (r = 0.84, p < 0.001). Comparative measurements of the retinal blood flow by SLDF and a commercially available laser Doppler flowmeter showed a linear and significant relation (flow r = 0.6, p < 0.0001, volume r = 0.4, p < 0.01). Capillaries of the retinal superficial vasculature or deep ciliary sourced capillaries of the optic nerve head became visible with a high resolution by the confocal technique dependent on the focus. Offline, the blood flow variables of areas of 100 microns x 100 microns were calculated. SLDF enables the visualisation of perfused capillaries and vessels of the retina and the optic nerve head in high resolution by two dimensional mapping of perfusion variables which are encoded by the Doppler signal. This method achieves simultaneously qualitative and quantitative evaluation of capillary blood flow of distinct areas of the capillary meshwork.

Dorsal connective tissue spaces of the thumb

Summary The clinical importance of the dorsal laminary connective tissue of the thumb is often emphasized with regard to spreading infectious inflammatory processes. The dorsal aponeurosis of the thumb contains connective tissue spaces, the function of which cannot simply be attributed to expanding the normal intercellular capillary spaces. These properties give the thumb a special status, separating it from the fingers motorically and morphologically. A plastic injection technique was used to display the various configurations of capillary spaces in the radio-dorsal region of fixed and unfixed hands and thumbs in order to describe them morphologically and topographically. Superficial, deep capillary and gliding spaces are structures limiting the mobility of the back of the thumb. They are topographically and functionally bound up with movements of the thumb saddle joint and carry the load of the radio-dorsal hand. The most exact reconstruction of the bordering elements of such functional spaces appears to be of special interest with regard to the complete restoration of thumb mobility.

In Vivo Confocal Scanning Laser Microscopy of Human Skin: Melanin Provides Strong Contrast

Confocal scanning laser microscopy of live human skin was performed to investigate the correlation of in vivo cellular and morphologic features to histology, the effect of wavelength on imaging, and the role of melanin as a contrast agent. We built a video-rate confocal scanning laser microscope for in vivo imaging of human skin. Using a 100 x microscope objective, we imaged high-contrast optical "sections" of normal skin, vitiliginous skin, and a compound nevus. In vivo "confocal histology" correlated well with conventional histology. The maximum imaging depth increased with wavelength: the epidermis was imaged with visible 400-700-nm wavelengths; the superficial papillary dermis and blood cells (erythrocytes and leukocytes) in the deeper capillaries were imaged with the near infrared 800-900-nm wavelengths. For confocal reflectance imaging, melanin provided strong contrast by increased backscattering of light such that the cytoplasm in heavily pigmented cells imaged brightly. In vivo confocal microscopy potentially offers dermatologists a diagnostic tool that is instant and entirely non-invasive compared to conventional histopathology.

Modelling the distribution of laser light in port-wine stains with the Monte Carlo method

Using the Monte Carlo method, the authors have calculated the distribution of absorbed light in skin during the laser treatment of port-wine stains. Their model includes the effect that the blood capillaries and epidermis have on the propagation of light through skin. It is more complete than those used by previous workers. Here, the authors change the number of scattering dimensions, the spot diameter, and the capillary separation and diameter, and the authors use the wavelengths 577 nm and 585 nm. One-dimensional scattering calculations are misleading but two-dimensional results suffice for large spot diameters. The model shows that changing the position or diameter of the capillaries has a larger effect on the distribution of absorbed light in the skin than changing the wavelength of the laser beam from 577 nm to 585 nm. Changing the wavelength does increase absorption in the deeper capillaries, but this is not significant. From their results, the authors discuss the optimal treatment of port-wine stains.

Optic nerve head blood flow in glaucoma

These days it is commonly accepted that multiple factors are involved in the etiology of glaucoma. Although many studies have demonstrated that the major risk factor for glaucoma is an increase in intraocular pressure (IOP), some studies, including epidemiologic studies, have suggested an association between glaucoma, especially primary open-angle glaucoma (POAG) and normal-tension glaucoma (NTG), and vascular factors. In this chapter, previous studies regarding the implications of optic nerve head (ONH) blood flow in glaucoma will be reviewed, and then our recent studies will be presented. Some population-based prevalence surveys demonstrated that lower perfusion pressure (blood pressure – intraocular pressure), especially diastolic perfusion pressure, was strongly associated with an increased prevalence of POAG or NTG in the US, Europe and Asia (Tielsch et al, 1995; Bonomi et al, 2000; Leske et al, 2002; Hulseman et al, 2007). These reports suggest that POAG including NTG is associated with alterations in factors related to ocular blood flow. There is also sufficient evidence that optic disc hemorrhage is an important risk factor for glaucoma progression (Daugeliene et al, 1999; Leske et al, 2003; Bengtsson et al, 2008; Prata et al, 2010). Additionally, increasing peripapillary atrophy, which might be related with hypoperfusion to the ONH, was reportedly associated with progressive glaucoma (Araie et al, 1994; Uchida et al, 1998; Daugeliene et al, 1999), and it has been reported that non-use of calcium channel blockers was significantly associated with the progression of visual field loss in NTG (Daugeliene et al, 1999). Clinically usable methods for the measurement of ONH blood flow include fluorescein fundus angiography, scanning laser Doppler flowmetry, and laser speckle flowgraphy. Fluorescein fundus angiography has multiple limitations in quantitatively evaluating ONH blood flow (Hayreh, 1997). Above all, once the dense capillary network in the surface nerve fiber layer of the ONH fills completely with fluorescein-stained blood, underlying ciliary vessels are masked so that no information can be obtained about the circulation in the deeper capillaries. Laser Doppler flowmetry is predominantly sensitive to blood flow changes in the superficial layers of the ONH and gives very little information about the prelaminar and deeper regions of the ONH (Petrig et al, 1999). Laser speckle flowgraphy (LSFG) can detect capillary blood flow in the ONH, probably around the laminar region, and is suitable for monitoring the time-course of its change (Sugiyama et al, 2010). LSFG was develped to facilitate the non-contact analysis of ocular blood flow utilizing the laser speckle phenomenon (Tamaki et al, 1995). Originally, normalized blur and square blur rate had been used as indexes of blood velocity, but later they were experimentally shown to be well correlated with blood flow rate. In the recent version of LSFG, a new parameter, mean blur rate (MBR), which is

The retinal microvasculature of spontaneously diabetic BB rats: Structure and luminal surface properties

Endothelial cell permeability and luminal surface anionic sites were studied in the retinal microvasculature of spontaneously diabetic rats. Horseradish peroxidase (HRP) was used as a tracer of pinocytotic transport, and cationized ferritin (CF) was used as a marker of luminal surface anionic sites. Diabetic and control rats were injected with HRP, and their retinas were fixed. Retinal tissue sections were then incubated in CF, reacted to visualize HRP, and prepared for quantitative electron microscopic analysis. In both control and diabetic rats treated with serotonin and histamine antagonists to prevent HRP-induced vascular changes, the endothelium formed a barrier to the tracer. Pinocytotic uptake was relatively low in most vessels. Reaction product was restricted to pinocytotic vesicles, tubular cisternae, and multivesicular bodies. HRP uptake appeared high in some of the deep capillaries of the diabetic retinas as compared with that of the controls, but the difference was not statistically significant. HRP-induced transendothelial permeability was observed in both control and diabetic rats when serotonin and histamine antagonist pretreatment was omitted. CF studies showed anionic sites in four luminal surface microdomains in control and diabetic endothelial cells. CF-binding, anionic sites were present on the plasma membrane, on all coated vesicles, on some uncoated vesicles, and on most diaphragms of uncoated vesicles. Plasma membrane binding was sparse and patchy in some diabetic vessels, especially in the deep vessels of rats that were not treated with the serotonin and histamine antagonists. However, statistical analysis showed similar numbers of plasma membrane binding sites in diabetic and control rats pretreated with serotonin and histamine antagonists. Our data suggest that the retinal microvasculature in diabetic rats remains normal in terms of permeability and luminal membrane anionic charge. (Preliminary report was presented at the Society for Neuroscience; M. E. C. Fitzgerald and R. B. Caldwell, 1987, Soc. Neurosci. Abstr., 13, 773.)

Mechanisms of mucosal injury in the stomach and duodenum: time-sequence analysis of morphologic, functional, biochemical and histochemical studies.

This review is based on results from our laboratory and those published by others, and is focused on the early stages of pathogenesis that can be studied mostly in animals. Gastric mucosal injury is analysed on the examples of ethanol- and aspirin-induced lesions. Ethanol (50-100%) rapidly penetrates the mucosa, causes directly and/or indirectly (e.g., release of vasoactive products) endothelial damage in superficial and deep capillaries and venules. The vascular damage results in increased vascular permeability and decrease in blood flow leading to complete circulatory standstill in superficial capillaries 1-2 min after intragastric administration of concentrated ethanol. The direct chemical damage to surface mucosal epithelium is then followed by hypoxia and deep hemorrhagic necrosis in 1-5 min (erosion or ulcer). Unionized aspirin initiates a similar and complex yet slower progressing and less extensive erosion than alcohol. Duodenal erosion and ulcer produced by cysteamine, mepirizole or MPTP are preceded by excess acid in the proximal duodenum. This could be due to increased gastric acid output (1-4 hr), decreased bicarbonate secretion or duodenal dysmotility (0.5-8 hr) preventing the proper mix of acid and base in duodenal bulb. Necrosis and desquamation of absorptive cells in duodenal villi are evident 2-4 hr, followed by villus amputation (4-8 hr), erosion and ulcer (8-24 hr). The pathogenesis of gastroduodenal mucosal injury can thus be reconstructed from results obtained with animal models and from human studies. The results should serve as a basis to design protective drugs that are active on the basis of pathogenetic events.

Materno-fetal barrier of the guinea-pig chorioallantoic placenta

Endothelial cell permeability and luminal surface anionic sites were studied in the retinal microvasculature of spontaneously diabetic rats. Horseradish peroxidase (HRP) was used as a tracer of pinocytotic transport, and cationized ferritin (CF) was used as a marker of luminal surface anionic sites. Diabetic and control rats were injected with HRP, and their retinas were fixed. Retinal tissue sections were then incubated in CF, reacted to visualize HRP, and prepared for quantitative electron microscopic analysis. In both control and diabetic rats treated with serotonin and histamine antagonists to prevent HRP-induced vascular changes, the endothelium formed a barrier to the tracer. Pinocytotic uptake was relatively low in most vessels. Reaction product was restricted to pinocytotic vesicles, tubular cisternae, and multivesicular bodies. HRP uptake appeared high in some of the deep capillaries of the diabetic retinas as compared with that of the controls, but the difference was not statistically significant. HRP-induced transendothelial permeability was observed in both control and diabetic rats when serotonin and histamine antagonist pretreatment was omitted. CF studies showed anionic sites in four luminal surface microdomains in control and diabetic endothelial cells. CF-binding, anionic sites were present on the plasma membrane, on all coated vesicles, on some uncoated vesicles, and on most diaphragms of uncoated vesicles. Plasma membrane binding was sparse and patchy in some diabetic vessels, especially in the deep vessels of rats that were not treated with the serotonin and histamine antagonists. However, statistical analysis showed similar numbers of plasma membrane binding sites in diabetic and control rats pretreated with serotonin and histamine antagonists. Our data suggest that the retinal microvasculature in diabetic rats remains normal in terms of permeability and luminal membrane anionic charge. (Preliminary report was presented at the Society for Neuroscience; M. E. C. Fitzgerald and R. B. Caldwell, 1987, Soc. Neurosci. Abstr., 13, 773.)

Flare of antigen-induced arthritis in mice after intravenous challenge. Kinetics of antigen in the circulation and localization of antigen in the arthritic and noninflamed joint.

Intravenous injection of methylated bovine serum albumin (mBSA) in mice with unilateral, chronic, mBSA-induced arthritis has been shown to cause a flare of smouldering arthritis without affecting the contralateral, noninflamed knee joint. We studied the kinetics of 125I-labeled mBSA in the blood, and the accumulation of antigen in both arthritic and noninflamed joints. The bulk of the antigen was eliminated from the blood within 10-30 minutes, and accumulation of antigen in the joints occurred mainly within this period. The amounts of antigen found in the arthritic joints were of the same order of magnitude as the amounts found in noninflamed joints. Autoradiography of whole joint sections revealed that, in arthritic joints, antigen was located primarily at the deep capillaries and large vessels, and in the noninflamed joints, antigen was located at the small superficial capillaries. Antigen was handled by granulocytes in the arthritic joint and by synovial lining cells in the noninflamed joint. Our data indicate that tiny amounts of antigen reach the synovial stroma in both normal and arthritic joints but cause inflammation only in the arthritic joints, because of local hyperreactivity.

Durikainema macropi gen. et sp. nov. (Muspiceoidea: Robertdollfusidae). A remarkable nematode from Macropodidae (Marsupialia).

Durikainema macropi gen. et sp. nov. (Muspiceoidea: Robertdollfusidae) is described from the mesenteric and hepatic portal veins of Macropus giganteus Shaw 1790, M. agilis (Gould 1842) and M. rufogriseus (Desmarest 1817) (Marsupialia: Macropodidae) from Queensland, Australia. It is also known from histological sections of hepatic portal veins of M. robustus Gould 1841, M. fuliginosus (Desmarest 1817) and Lagorchestes conspicillatus Gould 1842. The new genus resembles the Enoplina in cephalic and caudal characters and the Dorylaimina in other characters. Durikainema resembles Robertdollfusa Chabaud and Campana 1950 in its small form, absence of mouth oesophagus and anus, atrophied digestive tube, reduction of female genital apparatus to a uterine pouch, viviparity and cephalic cuticular inflation in larvae. It differs from this genus in its complex and well developed cephalic structures and its well developed body musculature in both sexes. Durikainema is tentatively placed in the Robertdollfusidae, Muspiceoidea. Larvae develop beyond firststage in the uterus of the female. They have been found in the non-peripheral blood of male and female M. giganteus, the lactating mammary gland of female M. agilis but not the non-lactating glands of the same female and in the deep capillaries of thigh skin of male M. agilis. Transmission of the parasite may be direct by a percutaneous or milk route, or indirect by a haemophagous arthropod.

Étude immuno-cytologique des neurones hypothalamiquesàLH-RH chez le foetus humain

The immunocytological study of LH-RH producing neurons was carried out on 3 newborns and 14 fetuses (from 10 to 36 weeks of age). Perikarya and fibers which were immunoreactive to anti-LH-RH IS were revealed by IF or IE in all the hypothalamus beginning with the 13th week. Important variations in neurons staining may translate “physiological” differences in their LH-RH charge but can be also the result of the diverse technical conditions. In three 16-week-old female fetuses, the large number of neurons (more than 150 per hypothalamus) permitted a good topographical and morphological study of them. They are scattered in vast areas of the anterior hypothalamus (lamina terminalis (LT) and septum), mediobasal and premammillary hypothalamus. The fibers which are particularly immunoreactive in semi-thin sections form a large hypothalamo-infundibular contingent in the posterior lip of the ME where they give rise to collaterals that terminate in contact with the capillaries of the mantelplexus, this taking place both before and after the apparition of the intra-eminential loops at the 16th week. Numerous in the LT, they terminate around the deep capillaries of the vascular organ or in contact with the ependymal epithelium. Some extra hypophyseal fibers go towards the epithalamus and the mesencephalon. To conclude, very early, in the human fetus the peptidergic LH-RH system resembles that described in adult primates; its role in the maturation and control of the gonadotropic cells is evoked.

Fluorescein angiography of degenerative lesions of the peripheral fundus and rhegmatogenous retinal detachment.

Since the number of cases for each of the conditions in our study was small, only preliminary conclusions can be made; in order to establish the fluorescein pattern of each of these peripheral retinal lesions, additional studies will be required. The following summarizes our preliminary observations. 1. Areas of retinal white-with-pressure or without and peripheral retinal cystoid degeneration did not reveal remarkable fluorescein angiographic findings. One exception was in an area of pigment epithelial disturbance characterized by atrophy and proliferation, which showed a "window and masking" effect of choroidal fluorescence. 2. Fluorescein angiography of areas of the fundus with lattice retinal degeneration showed little or no findings in early or mild cases. In severe or advanced cases, the affected retina revealed poor or absent perfusion caused by vascular occlusion. The retinal and choroidal circulation was devoid of fluorescein leakage. Advanced lesions displayed choroidal hypofluorescence in areas of pigment proliferation and hyperfluorescence in areas of pigment atrophy. 3. In advanced cases, occlusive vascular changes over areas of acquired retinoschisis were observed. There was intraretinal leakage of the dye from deep capillaries and pooling of the dye in cystic cavities near the margin of the retinoschisis. 4. There was no perfusion of the choroid and retina in the area of the hole and in the retina surrounding it. This finding suggests choroidal and retinal ischemia in the pathogenesis of a retinal hole. 5. Fluorescein angiography of retinal tears revealed fluorescein leakage along the edge of the tear and absent perfusion of the retinal flap. The retinal and choroidal circulation-around the tear was otherwise unremarkable. The choroidal fluorescein underlying the retinal flap was not visible, perhaps because it was masked by the retinal flap. 6. Our fluorescein angiographic findings in cases of rhegmatogenous retinal detachment confirmed those of others [7, 8, 10]. Transit of fluorescein through the retinal circulation was sluggish. The retinal capillaries were dilated. 7. In cases of rhegmatogenous retinal detachment which had become reattached surgically, areas treated with diathermy or cryoapplications showed absent or diminished choroidal and retinal perfusion. Leakage of the fluorescein from capillaries in the optic disc and retina in the posterior pole was sometimes persistent several months postoperatively.

The Treatment of Branch Central Retinal Vein Occlusion

SummaryThe treatments of branch retinal vein occlusion are reviewed and discussed.In the early stages, the loss of visual acuity is the result of the retinal arterial spasm induced by the thrombotic process. In the later stages the loss of vision is the result of the retinal osdema, the impaired blood supply, the increase in cell population and the leakage from deep capillaries.

Retinal capillary lesions in malignant hypertension.

IN RECENT years attention has been focused on the study of the retinal capillaries in systemic vascular disease, since there is little question that the dynamic physiology of the retina is dependent on the integrity of the capillary circulation. In diabetes, for example, capillary microaneurysms have been described by all workers in this subject as the most characteristic retinal capillary lesion in this disease. In explanation of retinal hemorrhages and so-called exudates, such local vascular disturbances as capillary and precapillary stasis and dilatation were suggested by Elwyn 1 some years before retinal capillary lesions were observed histologically. Anatomically, Michaelson and Campbell 2 in 1940 pointed out that the deep retinal capillary plexus is a more closely knit meshwork than the superficial and that venous stasis occurs mostly in these deeper capillaries, where exudates and hemorrhages are more numerous. For some years it has been recognized that in the study of