Fragility of pulmonary capillaries.

Although the pulmonary capillaries were discovered in 1661, the ultrastructure of the wall was not elucidated until 60 years ago. Electron micrographs then showed that only 0.2 µm of tissue separated the capillary endothelium from the alveolar space over much of the area. In retrospect this vanishingly small protective layer should have alerted physiologists to the potential fragility of the capillaries, but this was not appreciated until almost 40 years later. This predicament is unique to pulmonary capillaries. No other capillaries in the body are shielded from the outside environment by such a minute amount of tissue. Reasons why the fragility of the capillaries was not recognized earlier include an inappropriate comparison with the properties of systemic capillaries, the mistaken view that the pulmonary capillary pressure is always low, and a misleading use of the Laplace equation. Evidence for the fragility comes from physiological, pathological, and laboratory observations. As expected from evolutionary considerations, the fragility only becomes evident in the normal lung under exceptional conditions. These include elite human athletes at maximal exercise and animals that have developed the capacity for extreme aerobic activity. However, lung and heart diseases frequently cause capillary disruption. Remodeling of pulmonary capillaries occurs in humans in whom the capillary pressure rises over a long period. Neonatal capillaries are extremely fragile, presumably because they have never been exposed to increased transmural pressures. The capillaries conform to the general biological rule that tissue adapts its structure to carry out its required function.

Alopecia difusa en una niña de dos años de edad / Did the Duchess of Urbino have Frontal Fibrosing Alopecia?

No disponible

No disponible

Vocal nodules and edema may be due to vibration-induced rises in capillary pressure.

HYPOTHESIS: Vocal fold vibration may physically raise intravascular pressure to levels high enough to damage capillaries and result in leakage of erythrocytes. This type of injury is commonly seen in benign vocal fold lesions and is not well explained. STUDY DESIGN: Theoretical, retrospective. METHODS: The relationship of intravascular pressure to vibration frequency and amplitude is derived and confirmed with a physical blood vessel model, then applied to published human measurements to estimate human intravascular pressures. RESULTS: Vocal fold intravascular pressure is predicted to have a quadratic dependence on both frequency and amplitude. During speaking, the pressure may rise to over 20 cmH2O, and may reach levels far higher for screaming and singing. Such pressure magnitudes are known to trigger inflammatory cascades and can lead to fluid leakage. They also have the potential for pharmacologic control with beta-agonists. CONCLUSIONS: Intravascular pressure likely rises significantly during vocal fold vibration and may lead to the type of injury seen in benign vocal fold lesions. The results support voice therapy aimed at reducing vibratory amplitude. More vibratory amplitude measurements need to be performed in a wider range of subjects before the full range of human vocal fold vascular pressures can be estimated.

Complex decongestive physiotherapy decreases capillary fragility in lipedema.

Lipedema is a disproportional obesity featuring frequent hematoma formation due to even minor traumatic injuries. On the basis of clinical observations, complete decongestive physiotherapy diminishes the incidence of hematomas due to minor injuries beyond leg volume reduction. Hematoma development may be caused by altered capillary resistance (CR) or altered capillary fragility (CF). We measured capillary fragility (CF) before and after complex decongestive physiotherapy (CDP) to examine, whether CDP could reduce CF. 38 women with lipedema were included in the study. Twenty-one (21) patients were treated with CDP and 17 using exclusively moisturizers as the control group. CDP comprised once daily manual lymph drainage, intermittent pneumatic compression and multilayered short-stretch bandaging performed throughout a 5-day-course. CF was evaluated with the vacuum suction method (VSM) using Parrot's angiosterrometer in both groups. Decongestive therapy resulted in a significant reduction of the number of petechiae while no change was detected within the control group. Complete decongestive physiotherapy significantly reduced CF in patients with lipedema and this reduction may lead to reduced hematoma formation.

Microvascular and capillary perfusion following glycocalyx degradation.

Systemic parameters and microvascular and capillary hemodynamics were studied in the hamster window chamber model before and after hyaluronan degradation by intravenous injection of Streptomyces hyaluronidase (100 units, 40-50 U/ml plasma). Glycocalyx permeation was estimated using fluorescent markers of different molecular size (40, 70, and 2,000 kDa), and electrical charge. Systemic parameters (blood pressure, heart rate, blood gases) and microhemodynamics (vascular tone, velocity, and blood flow) remained statistically unchanged after injection of hyaluronidase, compared with inactivated hyaluronidase. Conversely, capillary hemodynamics were drastically affected. Functional capillary density, the capillaries perfused with red blood cells (RBCs), decreased by 35%, capillary Hct of the remaining functional capillaries increased from 16 to 27%, and penetration of 70-kDa fluorescent marker increased. Furthermore, plasma-only perfused capillaries statistically increased 30 min after hyaluronidase. The decrease in functional capillary density accounted for an increased RBC flux in the remainder of the capillaries, since the same number of RBCs had to traverse a reduced number of capillaries. Flux balances showed a reduction from baseline of 11% for the RBC flux and 20% for the plasma flux after treatment. These discrepancies are within the margin of error of the techniques used and could be explained by accounting for RBC over-velocity compared with plasma. These findings suggest that the decrease in the glycocalyx leads to capillary perfusion impairments.

Interventions for leg edema and varicosities in pregnancy. What evidence?

Leg oedema from venous insufficiency is not dangerous but it can cause women symptoms such as pain, feelings of heaviness, night cramps and paraesthesiae. Leg oedema can be a sign of pre-eclampsia when associated with raised blood pressure or proteinuria. The objective of this review was to assess the effects of treatment to relieve the symptoms associated with varicosity in pregnancy and to reduce leg oedema. We searched the Cochrane Pregnancy and Childbirth Group trials register in October 2004 for randomised trials of any form of treatment for varicosity and or leg oedema in pregnancy. Trial quality was assessed and data were extracted. Four trials of three different treatments were included. In one trial, women given rutoside capsules in the last 3 months of pregnancy noted an improvement in symptoms compared with placebo (relative risk 0.54 95% CI 0.32, 0.89). They had a decrease in ankle circumference at 36 weeks' gestation after 8 weeks of treatment, while women given placebo had a small increase. In one trial, women with ankle oedema had a small non-significant reduction in lower leg volume when treated with external pneumatic intermittent compression for 30 min. In another trial compression stockings prophylactically reduced the emergence of leg symptoms but not venous varicosities (relative risk 0.74 95% CI 0.59, 0.93). Lymphatic reflexology was studied in too few women to draw conclusions. In conclusions, rutosides appear to relieve symptoms of venous insufficiency in late pregnancy. However, it is not known if the drug is safe in pregnancy. External pneumatic compression appears to reduce ankle swelling and compression stockings reduce leg symptoms but not varicose veins.

Dotlike hemosiderin spots are associated with past hemorrhagic strokes in patients with lacunar infarcts.

BACKGROUND AND PURPOSE: Dotlike hemosiderin spots ongradient-echo T2(*)-weighted magnetic resonance imaging of the brain have been histologically diagnosed as old microbleeds associated with small vessel disease (SVD). The authors hypothesize that the presence of many dotHSs may be correlated with the fragility of small vessels and the recurrence of SVD, including lacunar infarction and deep intracerebral hemorrhage (ICH). METHODS: To investigate how dotHSs are related to past history of SVD, the number of subcortical or deep dotHSs was investigated in 146 patients with lacunar infarctions (95 men, 51 women, age 38 to 90 [66.6+/-9.4] years). They were divided into 2 subgroups according to history of deep ICHs or lacunar infarctions. The odds ratio (OR) for past history was estimated from logistic regression analyses with the number of subcortical or deep dotHSs as well as other factors. RESULTS: Of 146 patients with lacunar infarctions, 11 had past symptomatic ICHs and 19 had past symptomatic lacunar infarctions. An elevated rate of history of ICH was found for lacunar infarction patients with many deep dotHSs (>or=3; OR, 9.1; 95% confidence interval, 1.6-51, P=.015). However, history of lacunar infarction was not significantly associated with the number of subcortical or deep dotHSs. CONCLUSIONS: Our findings suggest that many deep dotHSs on T2(*)-weighted magnetic resonance imaging may be correlated with deep ICH-lacunar infarction type of SVD recurrence but not lacunar infarction-lacunar infarction type.

The effect of time and of vasoactive drugs on capillary leakage induced during myocardial contrast echocardiography.

BACKGROUND: Premature ventricular contractions (PVC), capillary leakage, and petechial hemorrhage can occur during myocardial contrast echocardiography (MCE). The effects occur as a result of the interaction of contrast agent microbubbles and the ultrasound, but the detailed etiology of the effects is not yet clear. This study tested the hypothesis that the capillary leakage results from a physiological response to injury, which might be protracted and modulated by vasoactive drugs. METHODS: Hairless rats were anesthetized and transthoracically scanned with a diagnostic ultrasound system (GE Vingmed System V) at 1.7 MHz with 1:4 triggered frames at end systole. The scan head and rats were mounted in a 37 degrees C water bath to assure free-field conditions and placement of the heart at a similar focal distance as humans. A tail vein was cannulated for injections of Optison contrast agent, vasoactive medications, and Evans Blue dye (EB). EB was injected as a marker of capillary leakage before or after scanning. RESULTS: PVCs, petechia, and capillary leakage occurred during ultrasound exposure of microbubbles in myocardium, with no effects detected in shams. The influence of the vasoactive medications propranolol and isoproterenol on the effects did not support the hypothesis. Capillary leakage occurred during and postexposure, but diminished for EB injection 20 minutes after scanning with or without isoproterenol pretreatment. CONCLUSION: MCE induced PVCs, petechia, and capillary leakage, all of which ended immediately or within 20 minutes after the examination. Contrary to the hypothesis of a physiological mechanism, the capillary leakage appears to be primarily a mechanical effect rather than a physiological response.

Abnormalities in the cerebral arterial system in osteogenesis imperfecta.

A 9-year-old girl with osteogenesis imperfecta (OI) type 4 was admitted to the hospital because of choreatic movement. Cerebral angiography demonstrated bilateral symmetrical stenosis of the proximal cavernous segment of internal carotid artery, prethrombotic occlusion of the M1 segment of left middle cerebral artery, and moyamoya-like collateral vascular structure arising from the right lenticulostriate arteries. After a literature review, these findings were interpreted as vasculopathic changes secondary to vascular fragility caused by the collagen abnormality in OI.

Rapid thawing increases the fragility of the cryopreserved arterial wall.

OBJECTIVE: To extend present knowledge of the biomechanical and structural changes which occur in the cryopreserved, rapidly thawed arterial wall. MATERIALS AND METHODS: Minipig iliac arterial segments were cryopreserved at -196 degrees C in either minimum essential medium or Wisconsin solution. Fresh segments served as the control group. After 1 month, the specimens were rapidly thawed (37 degrees C) and processed for biomechanical, ultrastructural, morphological and immunohistochemical (MMP-1, MMP-2, MMP-3 and MMP-9) analysis. Visualisation of apoptotic cells was performed by TUNEL method. For the mechanical distension analysis, an in vitro circuit was designed. RESULTS: The cryopreserved segments showed a 42% incidence of spontaneous fracture and the appearance of microfractures which affected the endoluminal third of the vessel. An accumulation of liquid in the subelastica was observed. An increased expression of wall-degradative enzymes (mainly MMP-2) was also observed following cryopreservation. No significant differences were detected in the proportional elasticity module or tensile strength of the specimen groups. No differences in mechanical distension were observed between groups after the vessel segments were subjected to the pulsatile circuit flow for 72 h. Cell damage was most intense in the specimens cryopreserved in Wisconsin solution. CONCLUSIONS: Cryopreservation in both the solutions employed, followed by rapid thawing, induce changes in the permeability which increase the fragility of the cryopreserved arterial wall. Both increased expression of wall-degradative enzymes and accumulation of liquid may contribute to graft failure after implantation.

Pathogenesis of classical swine fever: renal haemorrhages and erythrodiapedesis.

Thirty pigs were inoculated with a virulent isolate (Quillota strain) of classical swine fever (hog cholera) virus to establish the chronological occurrence of lesions in the kidney and to determine the mechanism responsible for renal haemorrhages. The study included the use of histopathological, ultrastructural, immunohistochemical (detection of viral antigen gp55, MAC387, lambda chains, CD3 and C1q) and morphometrical techniques (vascular area). Renal interstitial oedema and haemorrhages were detected from 7 days post-inoculation (dpi), associated with a slight interstitial mononuclear infiltrate and evidence of viral infection in macrophages and fibroblasts, and in a small proportion of lymphocytes. Viral infection was not detected in capillary endothelial cells. An intense mononuclear infiltrate, with B cells, T cells and small numbers of macrophages, was detected from 10 dpi. In the final phase of the experiment (14 dpi), slight proliferation and degranulation of mast cells were observed. Increased expression of the C1q component of complement was also detected. A significant increase in vascular area was observed from 7 dpi. These results suggest that haemorrhages observed in the kidneys of pigs inoculated with the Quillota strain resulted from erythrodiapedesis and increased vascular permeability, probably aggravated by mast cell degranulation in the final stage of the experiment. The results suggested that mast cell degranulation was linked to activation of the complement system.

Openings in frog microvascular endothelium induced by high intravascular pressures.

1. We have investigated the effects of microvascular pressures, high enough to rupture the vessel wall, upon the ultrastructure and permeability of mesenteric capillaries in pithed frogs. 2. The vessels were perfused via micropipettes with Ringer solutions containing bovine serum albumin (1 mg ml-1) and a few human red cells. After a perfused section of vessel had been closed downstream, pressure (applied via the micropipette) was raised in a series of steps of 10 mmHg, each lasting approximately 10 s, until the vessel ruptured. Fluid filtration through the vessel wall prior to rupture was estimated from the movements of the red cells. 3. Seven vessels were fixed in glutaraldehyde immediately after rupture and prepared for electron microscopy. The electron micrographs revealed openings in the vessel walls and thirty-six of these gaps were completely defined in runs of serial sections made on four of the vessels. Twenty-nine of these gaps passed through the endothelial cells (transcellular) and seven were intercellular. 4. The pressure at which a vessel ruptured, Pb, was measured in twenty-nine vessels and had a mean +/- S.E.M. value of 79.6 +/- 5.0 cmH2O. In ten of these vessels, which had a mean +/- S.E.M. Pb of 84.2 +/- 6.5 cmH2O, microvascular pressure was lowered immediately after the initial rupture and the vessel perfused at a pressure of 20 cmH2O. Pb was then remeasured and found to be 69.9 +/- 8.4 cmH2O, which was not significantly different from its initial value. 5. Hydraulic permeability (Lp) was measured in six vessels over the range of 15-30 cmH2O before and 10 min after the vessel wall ruptured at high pressure. Mean values were 5.5 x 10(-7) and 4.0 x 10(-7) cms-1 cmH2O-1 and were not significantly different. 6. At pressures equal to and 10 mmHg below Pb, small short-lived increases in filtration rate were observed. It is suggested that these may correspond to the increased permeability to fluid and macromolecules observed at high microvascular pressures in intact capillary beds.

Itching púrpura / Itching purpura

Se describe un caso de itching purpura o angiodermatitis pruriginosa diseminada. El trastorno consiste en una erupción petequial intensamente pruriginosa que se manifiesta inicialmente en las piernas, para luego diseminarse a tronco y miembros en el transcurso de algunas semanas, asociándose a descamación fina, pápulas y liquenificación. La etiología de la enfermedad es desconocida y se considera como una variedad diferente dentro del grupo de las dermatosispurpúricas pigmentarias. Su curso está sujeto a marcadas fluctuaciones, con períodos de mejoría y exacerbación . Puede esperarse una completa resolución del cuadro después de tres a seis meses, aunque en algunos casos puede llegar a durar hasta dos años

Flow-limited tracer oxygen distribution in the isolated perfused rat liver: effects of temperature and hematocrit.

We used the multiple-indicator dilution technique to examine the kinetics of tracer oxygen distribution and uptake in the rat liver perfused in a nonrecirculating fashion with blood. 51Cr-labeled 18O2-saturated erythrocytes, labeled albumin, sucrose and water (the tracers for oxygen and vascular, interstitial and cellular references) were injected simultaneously into the portal vein. Timed anaerobic samples were collected from the hepatic vein and analyzed by mass spectrometry for relative 18O2 enrichment and radioactivity. In a set of experiments performed at 32 degrees C, oxygen uptake was substantially diminished; tracer oxygen profiles approached those expected for a completely recovered, flow-limited substance. At 37 degrees C, much larger tracer oxygen sequestration occurred. Experiments were carried out at each temperature at higher and lower hematocrit, and oxygen consumption at each temperature was found to be independent of hematocrit. The tissue space of distribution for tracer oxygen relative to the total sinusoidal vascular content was influenced by the hematocrit: it was smaller at higher hematocrit and larger at lower hematocrit, as expected. The derived partition coefficient of oxygen for liver cells relative to plasma (expressed in terms of the liver and plasma water spaces) was, on average, 2.62 ml/ml; it was independent of the hematocrit. Analysis of the indicator dilution experiments indicates that the tracer oxygen is distributed into tissue in a flow-limited rather than a barrier-limited fashion, and that with this, an ongoing concomitant intracellular sequestration of tracer can be seen.

Exodontia e fragilidade capilar / Extraction of teeth e capillary fragility

O autor apresenta dois casos de extração de dentes em pacientes com problemas de vasos sanguíneos (fragilidade capilar). As fotos mostram equimoses faciais em ambos os pacientes. A prova de Rumper - Leede foi positiva em ambos os casos. Os sintomas desapareceram quando os pacientes foram submetidos a tratamento por drogas - vitaminas C, K e P. Em seguida os pacientes não mais exibiram sinais da doença sistêmica