Human Skin Capillaries Research Articles

Influence of Low-Intensity Laser Radiation on the Rheological Characteristics of Human Blood

The influence of low-intensity laser radiation (LLR) on the rheological characteristics of human blood has been investigated. The results of the investigation of the blood velocity in the human skin capillaries, the erythrocyte aggregation time, and the spectral width of scattering intensity fluctuations depending on the irradiation time are presented. It has been shown that laser irradiation leads to a decrease in the degree of aggregation of erythrocytes and, accordingly, to an increase in the velocity of blood microcirculation, which can be used for laser therapy and diagnostics and treatment of cardiovascular diseases (CVD). To explain the results obtained, a method of the LLR–biotissue interaction is proposed.

Measurement of the capillary blood cell velocity with a new laser Doppler anemometer in human skin capillaries outside the cuticle of the nail

The ability of furocoumarins to participate in the PUVA (Psoralen + UV-A) therapy against skin disorders and some types of cancer, is analyzed on quantum chemical grounds. The efficiency of the process relies on its capability to populate its lowest triplet excited state, and then either form adducts with thymine which interfere DNA replication or transfer its energy, generating singlet molecular oxygen damaging the cell membrane in photoactivated tissues. By determining the spin–orbit couplings, shown to be the key property, in the intersystem crossing yielding the triplet state of the furocoumarin, the electronic couplings in the triplet–triplet energy transfer process producing the singlet oxygen, and the reaction rates and lifetimes, the efficiency in the phototherapeutic action of the furocoumarin family is predicted as: khellin < 5-methoxypsoralen (5-MOP) < 8-methoxypsoralen (8-MOP) < psoralen < 4,5′,8-trimethylpsoralen (TMP) < 3-carbethoxypsoralen (3-CPS), the latter being the most efficient photosensitizer and singlet oxygen generator.

Capillary Blood Cell Velocity in Human Skin Capillaries Located Perpendicularly to the Skin Surface: Measured by a New Laser Doppler Anemometer

At very low diffusion weighting the diffusion MRI signal is affected by intravoxel incoherent motion (IVIM) caused by dephasing of magnetization due to incoherent blood flow in capillaries or other sources of microcirculation. While IVIM measurements at low diffusion weightings have been frequently used to investigate perfusion in the body as well as in malignant tissue, the effect and origin of IVIM in normal brain tissue is not completely established. We investigated the IVIM effect on the brain diffusion MRI signal in a cohort of 137 radiologically-normal patients (62 male; mean age = 50.2 ± 17.8, range = 18 to 94). We compared the diffusion tensor parameters estimated from a mono-exponential fit at b = 0 and 1000 s/mm2 versus at b = 250 and 1000 s/mm2. The asymptotic fitting method allowed for quantitative assessment of the IVIM signal fraction f* in specific brain tissue and regions. Our results show a mean (median) percent difference in the mean diffusivity of about 4.5 (4.9)% in white matter (WM), about 7.8 (8.7)% in cortical gray matter (GM), and 4.3 (4.2)% in thalamus. Corresponding perfusion fraction f* was estimated to be 0.033 (0.032) in WM, 0.066 (0.065) in cortical GM, and 0.033 (0.030) in the thalamus. The effect of f* with respect to age was found to be significant in cortical GM (Pearson correlation ρ ​= ​0.35, p ​= ​3*10−5) and the thalamus (Pearson correlation ρ = 0.20, p = 0.022) with an average increase in f* of 5.17*10−4/year and 3.61*10−4/year, respectively. Significant correlations between f* and age were not observed for WM, and corollary analysis revealed no effect of gender on f*. Possible origins of the IVIM effect in normal brain tissue are discussed.

Synchronous Measurements of Blood Pressure and Red Blood Cell Velocity in Capillaries of Human Skin

We have devised a system for analyzing the temporal coherence of capillary pressure (CP) and capillary red blood cell velocity (CBV) variations in humans. The system is designed to measure human blood pressure in skin capillaries by direct cannulation while simultaneously measuring red blood cell velocity in the same capillary by video microscopy. The servo-nulling pressure measurement system allows the dynamic recording of capillary pressure with a flat frequency response of about 12 Hz. Computerized data acquisition is synchronized with the frame code of a U-matic video recorder, which records the capillaroscopic picture for later computerized off-line analysis of capillary red blood cell velocity. Measurements of simultaneously recorded CP and CBV in healthy volunteers show synchronized pulsation. Minimal pulsatile variations in CP values result in marked variations of CBV. In addition, minor fluctuations (3-4 cycles per minute) in CP are accompanied by marked changes in CBV. This system may help provide information about microvascular pathophysiology in skin diseases before and after treatment.

Cultivation of human dermal microvascular endothelial cells in vitro: Immunocytochemical and ultrastructural characterization and effect of treatment with three synthetic retinoids

A new reliable and reproducible technique to culture endothelial cells from the small vessels and capillaries of human skin is introduced, and proliferation and differentiation of the growing cells are characterized. The endothelial origin of the culture cells was confirmed by light- and electron microscopy and by labelling with Ulex europaeus Agglutinin I and an antibody against Factor VIII-related antigen. Further immunocytochemical characterization showed that 92-100% of the cells were positive for beta 2-microglobulin and the entire cell population expressed vimentin, whereas cytokeratins, desmin, HLA-DR antigen, Leu 6 and S 100 protein, could not be detected. As vascular endothelium is a common site of inflammation and retinoids have been shown to be of good clinical efficacy in some chronic inflammatory skin diseases, we investigated the influence of etretinate, etretin and isotretinoin on proliferation and antigen expression of our culture cells. All retinoids applied inhibited proliferation of endothelial cells in a dose- and time-dependent manner whereas they induced neither HLA-DR nor intercellular adhesion molecule-1 (ICAM-1). Furthermore, none of the retinoids applied influenced the gamma-interferon-induced expression of these surface antigens on endothelial cells. Our results suggest that the action of retinoids in skin inflammation is not mediated by modulation of HLA-DR or ICAM-1. The cell culture technique described here is an interesting and reliable model for studying the influence of drugs on endothelial cell growth and differentiation in vitro.

Ultrastructural localization of alpha- l-fucose, factor VIII related antigen and vimentin in endothelial cells of human skin blood vessels using the low temperature embedding technique with Lowicryl K4M

The present study was performed to investigate the ultrastructural localization of the binding sites of the lectin Ulex europaeus agglutinin, Type I (UEA) and the antibody against factor VIII related antigen (F VIII RAG), both widely used as vascular markers in human skin capillaries at light microscopy level. In addition the ultrastructural localization of vimentin, the major protein of the endothelial intermediate filaments, was demonstrated in human vascular endothelial cells (EC) in situ. The low temperature postembedding technique with Lowicryl K4M with subsequent application of gold labelled antibodies provided both well preserved antigenicity and morphology. The antigenic site of UEA, alpha- l-fucose containing glycohydrate residues, was primarily found in or near the luminal plasma membrane of EC. Gold particles representing the sites of F VIII RAG were located in the Weibel-Palade bodies (WPB) of EC. The ultrastructural staining pattern of the anti-vimentin antibody showed an exclusive labelling of the intermediate filaments of EC.

Relative hematocrit in human skin capillaries and its relation to capillary blood flow velocity

Blood flow velocity (CBV) and relative hematocrit (Hct) in human nailfold capillaries were measured by noninvasive video-densitometric cross-correlation technique. Through a microscope a video recording was made of the flow of blood cells in the skin capillaries. Two small videophotometric windows were positioned along a monitored capillary. The velocity in the capillary was measured by continuously computing the delay-time to maximum cross-correlation between identical optical signals generated at the two windows by blood cells and plasma gaps. The relative hematocrit was deduced from continuous records of the video-densitometric output of one window. Relative calibration was accomplished by assigning zero hematocrit to the output of the window in the absence of red cells, and 100% to the maximum output recorded during a period of 5 min. More or less periodic fluctuations of CBV and relative Hct were found in most capillaries studied. The frequency of the fluctuations was in the order of 5 to 10 cycles per minute. The changes of flow were almost invariably accompanied by changes in hematocrit. In most instances changes in CBV preceded changes in Hct by one to several seconds. The normal vasomotion appears to cause a continuous change in the proportion between red cells and plasma until the diameter of the arteriole is so narrow that erythrocytes are mechanically prevented from passing into the capillary. Prior to complete closure of the arteriole there is sometimes a flow of plasma such that the capillary is empty of blood cells when flow stops. Adjacent capillaries seem to have the same major vasomotion pattern but individual variations are often seen.

Langerhans cells in normal human skin capillaries

Cells with Langerhans granules are reported for the first time in normal human skin capillaries.

Blood pressure fluctuations in human nailfold capillaries

Dynamic blood pressure was measured in 33 human finger nailfold capillaries after direct cannulation with glass micropipettes by means of a resistance servo-nulling pressure measuring method. ECG, finger pulsations, and respiratory thorax excursions were monitored simultaneously. All recordings exhibited pulsatile oscillations related to the cardiac rhythm. These oscillations resembled the wave forms of arterial pulsations with steep upstroke and dicrotic notch when the pressure amplitudes were above 10 mmHg. There was no apparent dependence on respiration. In 12 instances, pressure fluctuations with frequencies ranging from 0.2 down to 0.07 Hz were observed in both the arteriolar and venular limb. Blood pressure in human skin capillaries is pulsatile and subject to remarkable fluctuations in the arteriolar as well as in the venular limb, systolic pressure values ranging from 14 to 71 mmHg and from 11 to 52 mmHg, respectively.

A microscope-television system for studying flow velocity in human skin capillaries.

A noninvasive technique for studying blood flow dynamics in human skin capillaries is described. A light microscope combined with a closed-circuit TV system was used to monitor and record capillary blood flow velocity on video tape. Arterial pulsations were recorded plethysmographically and converted into video signals by modulating the position of a square, white area in the televised scene. Twelve healthy subjects were studied. The mean (+/- SD) resting capillary blood flow velocity was 0.65 +/- 0.3 mm/s at an average skin temperature of 30.4 +/- 2.3 degrees C. Spontaneous fluctuations at a frequency of 6-10 cycles/min were observed in most subjects. A well-pronounced flow pulsatile component could be demonstrated in all capillaries studied. The technique can be used in clinical practice for studying the physiology and pathophysiology of cutaneous microcirculation in man. It can be expected that the method may become an important diagnostic tool in diseases that involve disturbances of the microcirculation, such as diabetes, hypertension, and atherosclerosis.

Intermittent blood flow in the capillaries of human skin: Bordley, James, III, Grow, Max H., and Sherman, William B.: Bull. Johns Hopkins Hosp. 62: 1, 1938

Intermittent blood flow in the capillaries of human skin: Bordley, James, III, Grow, Max H., and Sherman, William B.: Bull. Johns Hopkins Hosp. 62: 1, 1938

Studies of the Roentgen Erythema of the Human Skin

SINCE the publication of the first paper in this series, we have extended our observations to studying the behavior of the skin capillaries after exposure to filtered roentgen rays of short wave length and also to ultra-violet radiation. Considerable time was taken in developing a photographic method which permits the recording of the capillary appearance on a plate. Although we succeeded in producing good negatives, this procedure in its present form takes so much time in the preparation of a single record that we had to return to the drawing of the microscopic picture, as described in the previous article. We are striving, however, to perfect this photographic method because it is the ideal way to employ in this research. In the meantime Niekau (1) and Crawford and Rosenberger (2) have designed an apparatus for the cinematographic reproduction of the skin capillaries, a method which shows the continuously occurring changes in the pulsating blood vessels. The writer had the privilege of demonstrating before the Radiological Society of North America, in Milwaukee, the motion picture film “Human Skin Capillaries and Their Changes during Circulation of the Blood,” made by Professor Niekau, and wishes to take this opportunity of expressing his appreciation to the author for his courtesy. Crawford and Rosenberger studied the capillaries under normal conditions (3) and in cases of auricular fibrillation (4), and analyzed the observations made on the motion picture film. We employed again the skin microscope (Mueller) and followed the technic described in detail in a recent paper (5). Only patients (numbering 87) who were to be submitted to therapeutic exposure were used in our investigations except in such investigations as dealt with ultra-violet rays. In this case, we felt quite at liberty to choose normal adults. It may be stated that all observations reported are based on the study of the effect of a full erythema dose given in a single exposure or in quarters on four successive days. Care was taken to select patients who were not suffering from diseases of the heart or blood vessels, nephritis, toxic goiter, diabetes, or neuroses. It is well known that in these conditions the capillaries are much more susceptible to stimuli. 1. Exposure to filtered roentgen rays. The radiation used is defined as follows: 200 K.V., 25 ma., 50 cm. F.S.D., 0.5 or 1.0 Cu. plus 1.0 Al., lambda effective 0.16 and 0.14, respectively. The erythema dose for a field of 20 × 20 cm. equals 14 and 22 minutes, or 1,500 and 1,700 R-units (measured on the patient), respectively. The parts of the body examined were arms, chest, abdomen, upper thigh, back, and neck. No important difference except slight variation in the degree of the reaction owing to the different sensibility of certain parts of the skin could be noted.