SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Graafian follicle growth and development and Doppler flow analysis of blood vessels in the wall of the follicle, was analyzed. Twelve patients with primary infertility were observed between days 12 to 15 of the cycle. Analysis of resistance index (RI) and pulsatility index (PI) of the wall vessels was performed. Statistically significant difference in RI and PI indices in preovulatory and post-ovulatory period was observed.
Hepatic ischemia-reperfusion (I/R) is characterized by circulatory and metabolic derangements, liver dysfunction, and tissue damage. However, little is known about the causative role of I/R-induced microcirculatory disturbance on the manifestation of postischemic reperfusion injury. Therefore, the intention of the study was to assess changes of hepatic microvascular perfusion (intravital fluorescence microscopy) as related to hepatic morphology (light/electron microscopy), hepatocellular integrity (serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities), and excretory function (bile flow). Sprague-Dawley rats were subjected to 20 minutes (group B, n = 9) and 60 minutes (group C, n = 9) of left hepatic lobar ischemia followed by 60 minutes of reperfusion. Sham-operated animals without ischemia served as controls (group A, n = 10). Lobar ischemia for 20 minutes followed by reperfusion resulted in a significant reduction of sinusoidal perfusion rate (93.9 +/- 1.4%; P < 0.05) and a decrease in erythrocyte flux (90.0 +/- 5.6%) when compared with controls (99.4 +/- 0.2 and 97.9 +/- 2.7%). This was accompanied by a significant increase of serum AST and ALT activities (P < 0.05) and a reduction of bile flow (P < 0.05). Prolongation of lobar ischemia (group C, 60 minutes) aggravated postischemic reperfusion injury (sinusoidal perfusion rate: 87.4 +/- 2.9%; erythrocyte flux: 62.1 +/- 8.4%) and was paralleled by severed hepatocellular damage. Electron microscopy of postischemic tissue demonstrated alteration of nonparenchymal cells (swelling of sinusoidal lining cells and widening of Disse's space) and substantial parenchymal cell damage (swelling of mitochondria, disarrangement of rough endoplasmatic reticulum, vacuolization, complete cytoplasmic degeneration). Initial postischemic increase in serum AST and ALT activities and reduction of bile flow directly correlated with the extent of microcirculatory failure (P < 0.01), ie, impairment of sinusoidal perfusion and decrease of erythrocyte flux, indicating the decisive role of microvascular perfusion failure for the manifestation of hepatic tissue damage and liver dysfunction.
Since the introduction of bileaflet heart valve prostheses their clinical use has continued to escalate. The first of this valve type was the Standard St. Jude Medical (SSJM) prosthetic heart valve in 1977. The Carbomedics prosthetic heart valve (CPHV), introduced in the late 1980s, was intended to improve on the design of the SSJM bileaflet valve. The design changes in the CPHV valve, relative to the SSJM valve, may have the potential to affect its flow fields. This study, using flow visualization laser Doppler velocity measurements and color Doppler flow mapping, was intended to evaluate how these changes affect the flow fields in the near vicinity of the CPHV valve. The study was conducted in an in vitro pulse duplicator system. In the flow visualization study, the flow fields observed with the CPHV valve were quantitatively similar to those seen with the SSJM valve. Centralized jet-like flows with flow separation/stagnation were observed in the illuminated planes. The jet-like flows from the two lateral orifices were broader than that observed from the central orifice for both the CPHV and the SSJM valves. This fact implied that the major part of the volumetric flow was through the two lateral orifices, rather than the central orifice. In the laser Doppler velocity measurements, it was found that the flow field downstream of the SSJM valve was slightly more evenly distributed than that with the CPHV valve. In addition, the extent of the flow separation regions with the CPHV valve were slightly larger than with the SSJM valve. The slight differences in velocity profiles between the SSJM and the CPHV valves were due to the differences in leaflet opening angle. However, the levels of flow turbulence with the CPHV and the SSJM valves were found to be of the same order of magnitude. The results of the flow visualization and LDA velocity and turbulence measurements obtained in the study indicate that the differences in flow fields in the immediate vicinity of the CPHV valve relative to the SSJM valve are insignificant.
Explore the source record for details and available documents.
Using the laser Doppler technique patterns of spontaneous oscillations of skin blood flux within the low frequency band (< 10 min-1; LF waves) were analysed in 12 healthy controls and 24 patients with different degrees of peripheral arterial occlusive disease (PAOD). Measurements were performed at 5 different sites at the dorsum of the foot in healthy controls and patients with severe claudication or rest pain and/or gangrene due to PAOD. Patterns were classified as "periodic", "aperiodic" or "no flux motion". The aperiodic pattern was characteristic for skin blood flux of controls. In severe claudication prevalence of periodic LF oscillations significantly increased (p < 0.05) whereas it decreased again in patients with severe ischemia. In the latter group, LF waves often were completely absent. Periodic LF waves mainly occurred between an ankle/arm pressure ratio of 0.4 to 0.8. We suggest that periodic LF waves most likely ar the result of a synchronized vasomotor activity of different arterioles within the sample volume, whereas the aperiodic pattern may resemble the net effect of simultaneous activities of different control mechanisms on skin blood flow. Based on animal experiments it is hypothesized that decreased postocclusive driving pressure and flow in patients with advanced PAOD may be the stimulus for synchronized arteriolar vasomotion.
Aim of the study was to verify the relationship between syndrome X and generalized microangiopathy. Three groups of patients were selected: Group A, 11 patients with typical syndrome X; Group B, 8 patients with atypical chest pain; Group C, 12 control normal subjects. Microvascular circulation was investigated with a laser Doppler Periflux PF3 at rest (15 min); during ischemia (3 min); during post-ischemic hyperemia on the plantar side of the big toe (where arterovenous anastomoses are particularly abundant) and on the dorsum of the foot (where these anastomoses are very scanty). During each recording we calculated: the mean flux value (FV); the mean concentration of moving blood cells (CMBC); the FV/CMBC ratio (which is related to the flow velocity); the mean percent increase of the three parameters during hyperemia. Patients with syndrome X as compared to the other subjects showed: 1) a significantly higher FV/CMBC ratio at rest and during hyperemia both on the plantar side of the big toe (respectively p = 0.01 and 0.015) and on the dorsum of the foot (respectively p = 0.011 and 0.006). These findings suggest a higher flow velocity in microvascular circulation; significantly lower percent increase of FV and CMBC during hyperemia in the plantar side of the big toe (respectively p = 0.04 and 0.014) but not on the dorsum. The increase of flow velocity at rest and low vasodilatatory reserve after ischemia in an area which is rich of arterovenous anastomoses in patients with syndrome X might be explained by the presence of a basal arterovenous hyperstomia.
PURPOSE: To study retinal blood flow (RBF) during pregnancy in subjects with and without diabetes and to relate the changes to progression in diabetic retinopathy. METHODS: RBF in a major temporal retinal vein was measured, where possible, during all three trimesters (T1 to T3) and the postpartum period (PP) using laser Doppler velocimetry (measuring velocity [V]) and monochromatic fundus photographs (measuring diameter [D]). RESULTS: In the subjects without diabetes (n = 19), no significant change in RBF was demonstrated. V was significantly greater in T3 than in PP (P = 0.01). D was significantly smaller in T1 to T3 than in PP (P < or = 0.01). RBF in the subjects with diabetes was significantly higher in T2 and T3 than in PP (P < 0.05). V increased from T1 to T2 (P = 0.04) and decreased from T2 to PP (P = 0.001) and from T3 to PP (P = 0.002). The only significant change in D was a smaller value in T1 than in PP (P = 0.003). However, it was only those subjects whose DR progressed (n = 11) who had a significant increase in RBF during pregnancy (P = 0.0001). CONCLUSIONS: These data suggest that the hyperdynamic circulation present in pregnancy led to compensatory retinal vessel constriction (autoregulation) in the group without diabetes; this was largely absent in the patients with diabetes, with resultant increase in retinal blood flow associated with worsening retinopathy. This finding lends further support to the hypothesis that increased retinal blood flow is a pathogenic mechanism for diabetic retinopathy.
Aim of the study was to compare different techniques of monitoring for vascular accesses in our chronic hemodialysis patients. Twenty seven patients (14 men, 13 women) were investigated. The accesses studied consisted of 19 arteriovenous fistulas and 8 vascular protheses. Twenty-four were trouble free, venous pressure was high in two, one was difficult to puncture. Three measurements of recirculation percentage were made for each patient, as well as a color Doppler flow imaging, and a digital angiography of the access. Recirculation measurements were normal for all patients including those with functional abnormalities. A stenosis was found 9 times with the Doppler and 10 times by angiography, there being disagreement between the two techniques in one case. The location of the stenosis was the same in the 9 concordant cases. There was a very strong correlation between the degree of stenosis found using the two techniques (p < 0.0001). In conclusion, measurement of recirculation appears to us to be of no interest for verifying a vascular access. On the other hand, the color Doppler seems to be an excellent choice for detecting an abnormality. An arteriographic confirmation seems necessary before correction.
The authors describe the main characteristics of the Doppler method in the early diagnosis of chronic fetal distress, and report their personal results in the study of 51 high risk pregnancies. In their study the fetal doppler ultrasound findings were correlated with birth weight related to gestational age, and neonatal morbidity. The parameters established from the doppler ultrasound assessment were the placenta resistance (calculated from the formula of Pourcelot: R = S-D/S applied to the umbilical artery) and the cerebro-placental index, Rp/Rc, Rc being the index of cerebral arterial resistance. The diagnosis performance of the method appeared very good: the Rp index was found to be highly specific for hypotrophy (85,7%) and for neonatal morbidity (90%), the RCP index adding its own good sensitivity (85% for hypotrophy and 83,3% for neonatal morbidity). The authors conclude upon the interest to study simultaneously the fetal umbilical and cerebral arterial circulations. The pathological significance of the two indexes appears different so that they are to be complementary in the evaluation of fetal distress.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
We examined psoriatic lesions on the upper legs in 20 patients, using a two-dimensional Laser-Doppler-Scanner (Laser Doppler Perfusion Imager LDI, Lisca Development, Linköping/Sweden). The plaques were evaluated weekly during therapy with dithranol. Five plaques were reconstructed three-dimensionally before and after therapy (reconstruction program ANAT 3D, SIS, Münster, Germany). The psoriatic plaque was represented in the Laser Doppler Perfusion image as a sharply demarcated, hyperperfused area. The perfusion of the plaques dropped during therapy with dithranol to just slightly increased values, compared with normal skin (2.04 arbitrary units AU, healthy skin 1.1 AU). Using three-dimensional reconstruction, we investigated the volume of dermal vessels and the density of papillae. When compared, the volume of papillary vessels was twice as large in psoriatic as in healthy skin. The number of the papillae per square millimetre, detected by three-dimensional reconstruction, was not reduced significantly during therapy. We think that the increased perfusion of the psoriatic plaque is due to the combination of morphological (dilatation of vessels), dynamic (increased blood flow) and optical effects (reduced scattering and increased sampling depth of the laser-beam in acanthotic tissue).
Nonsteroidal anti-inflammatory drugs (NSAIDs) predispose to acute and chronic renal failure, possibly due to intrarenal hemodynamic effects. In anesthetized volume-expanded rats, total renal blood flow (RBF) was measured by an ultrasonic flowmeter placed around the left renal artery, superficial cortical blood flow (sCBF) by a flunt laser-Doppler probe placed over the kidney surface, mid-cortical (mCBF) and outer medullary blood flow (oMBF) by a needle laser-Doppler probe inserted into the renal parenchyma. Indomethacin (5 mg/kg i.v.) caused no significant change in RBF (n = 9) or mCBF (n = 6) and slightly increased sCBF (to 106 +/- 2% of baseline; n = 8, p < 0.05). By contrast, oMBF dropped significantly (to 55 +/- 4% of baseline; n = 8, p < 0.0001) within 30 min of indomethacin administration. Similarly, acetylsalicylate (50 mg/kg i.v.) slightly increased sCBF (to 110 +/- 3% of baseline; n = 5, p < 0.05) but caused a significant drop in oMBF (to 54 +/- 2% of baseline; n = 5, p < 0.0001). These results suggest that NSAIDs cause a profound and selective reduction in oMBF which may predispose to acute or chronic intrarenal damage by aggravating medullary hypoxia.
Although transcutaneous Po2 (tcPo2) and Pco2 (tcPco2) measurement was originally developed for the non-invasive Pao2 and Paco2 monitoring, its utilization in dermatology is discussed in this article. Our experimental and clinical studies have revealed that tcPo2 is easily influenced and reduced by various skin changes, such as hyperkeratosis, acanthosis, cellular infiltrate and fibrosis as well as the circulatory disturbance in the skin, and that tcPco2 is kept stable except in ischemic or bullous lesions. Although tcPo2 could be a marker reflecting the severity of some lesions, simultaneous measurement of tcPco2 and cutaneous blood flow would offer more precise information about the circulation and respiration in the skin.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Bioengineering techniques for examination of the skin, measuring principles and sources of error relative to technique, study design, measuring conditions and variability related to test subjects and preconditioning are reviewed. Principles of validation and standard operating procedures (SOP) are discussed, including guidelines for measurement of transepidermal water loss (TEWL) and laser Doppler cutaneous blood flow. Today typical errors are not related to a measuring device but to the way it is used.
Many authors hypothesize that mitral valve prolapse (MVP) can be, in most cases, only a clinical sign of a primitive and systemic disorder of the connective tissue, like in Marfan Syndrome (MS). In our previous works we supported the presence of morphological and functional alterations of the microcirculation in patients affected by MS. In order to characterize a possible common denominator between these pathologies we have studied the cutaneous microcirculation in a group of patients affected by MVP, divided into 2 groups: anatomic MVP (MVP) and MVP syndrome (MVPS). The morphologic parameters have been investigated by nailfold capillaroscopy while digital laser-Doppler was used to study skin flowmetry. The results have been compared with a control group. Capillaroscopic remarkers showed an architecturally disorganized microvasculature with aspects related to a reduced compactness of the microvasculature unit with a significatively higher score compared with controls (7.3 +/- 2.9 vs 3.6 +/- 1 p less than 0.0005). Laser-Doppler flowmetry showed a significatively reduced rest flow; ischemic test showed: spike time 48.9 +/- 36.9 vs 15.3 +/- 7.7 s (p less than 0.0005), hyperemic acme 6.6 +/- 2.7 vs 12.5 +/- 8.4 UP (p less than 0.002); % increase 32.1 +/- 20.2 vs 51.5 +/- 15.4 (p less than 0.002). Thermic test showed a significatively higher thermic acme 8.7 +/- 4.2 vs 12.6 +/- 9.11 UP (p less than 0.05). These results appeared to be correlated with stage pathology as it was observed a severe microvasculature disorders in MVPS. Therefore we suppose that a phenotypic continuum may exist between MS and MVP.