Gregory E. Brill

Investigation of statistical properties of lymph-flow dynamics using speckle microscopy

At different pathological stages, the changes both of blood and lymph microcirculation parameters are observed. These parameters are of great importance in diagnostics. The type of these changes may indicate both the kind and the degree of disease. Investigation of the behavior of dynamic characteristics of these flows at different stages is of special interest. In this paper the peculiarities both of blood and lymph motion have been considered. The further development of speckle-interferometrical method has been carried out for the investigation of the dynamic characteristics of blood and lymph flows in microvessels. Analysis of two dynamic parameters which had been introduced in previous papers concerning this problem, is made in this paper. The influence of lymphotropic agent both on lymph flow and its dynamic characteristics is also discussed.

Comparison of lymph and blood flow in microvessels: coherent optical measurements

In the present study the characteristics of blood and lymph microcirculation are investigated. The microcirculation was studied on small intestine mesentery in norm and during NG-nitro-L-arginine (L- NNA) application. The direct measurement of lymph flow velocity (parameter V) in individual microvessels was based on the technique of light intravital videomicroscopy. The first spectral moments of Doppler signal characterizing the mean velocities of lymph and blood flow in microvessels (parameters M1L and M1B) were measured by speckle- interferometrical method. Simultaneously, diameters of blood and lymph microvessels as well as parameters of phasic contractions and valve function of lymphatics were registered. The mean diamters of investigated lymphatics and venules were 170±20 μm and 8±0.5 μm, correspondingly. In 24% of lymph microvessels phasic contractions were observed. The mean flow velocity in blood microvessels was 10 times more than the one in lymphatics. L-NNA application led to variable effects on diameter of lymphatics, increased the number of microvessels with phasic contractions and modified parameters of these contractions. The mean velocity of lymph flow (V) was increased. The mean value of M1L was not changed; the M1L maximum in 75% of the lymphatics was increased. In 88% of venules M1B was decreased on 25±7%.

Development imaging and experimental model for studying pathogenesis and treatment efficacy of postmastectomy lymphedema

The experimental model was created during an abdominal dissection of the rat mesentery and ligation of the collecting vein of mesentery. It was found that mesentery edema was developed for 20-30 min. Simultaneously monitoring of main the parameters of blood and lymph flow revealed significant increasing of interstitial water amount (up to 3 times), reduction of blood microcirculation, increasing of blood vessels permeability, decreasing of lymph microvessels diameter, phasics contractions, and lymph flow velocity.

The diagnosis of lymph microcirculation in experimental studies on rat mesentery in vivo

The many biological and medical problems associated with microlymphatic functioning and its disturbances at different diseases, include primary and secondary lymphedema, inflammation, lymphatic malformations, and so on. It is important both to establish an adequate animal model for study lymph microcirculation in vivo and to match it with corresponding diagnostic techniques. The rat mesentery has been successfully used in experiments focusing on the microcirculation, including small lymphatics. Among optical methods the transmittance microscopy is most widely employed to study microcirculation. We have undertaken following investigations: development and evaluation of capability of transmission microscopy for in vivo studies of microcirculation; obtaining of single cell images; estimation of lymph microcirculation parameters, including the relation of forward to backward flow in intact lymphatics; regulation of microlymphatic function by nitric oxide and study of microlymphatic disturbances at the experimental lymphedema. Although interesting data has been obtained, the transmission microscopy has the relatively low absorption sensitivity and prevents obtaining good absorption contrast. To obtain more comprehensive physiological data, the further development and improvement imaging of rat mesentery is discussed with focus on new combined optical imaging systems which integrate recent advances in video-transmission and photothermal (PT) microscopy, PT fluid velocimetry, and laser spectroscopy.

Laser speckle flow velocity sensor for functional biomicroscopy

Laser speckle based direction sensitive flow velocity sensor has been developed for use with transmission microscope for in vivo bioflow monitoring. The instrument allows for measurements of blood and lymph flow parameters in micro vessels simultaneously with biomicroscopic measurements. The performance of the instrument was tested using the model of lymph micro vessel and was illustrated by the results of in vivo experiments on micro vessels of rat mesentery.

In-vivo lymph dynamic monitoring using speckle-correlation technique and light microscopy

In this work we described the new modification of experimental setup designed on the basis of transmission microscopy and high-resolution speckle-correlation technique. This combined technique provides the simultaneous speckle and video registration of lymph dynamics that allows one to calibrate the speckle-correlation velocity sensor and to determine an absolute flow velocity and its direction. As a result many parameters of lymph dynamic were measured quickly, conveniently and simultaneously and a new data about the lymph flow velocity and other functions of microcirculation were received. The results of the experimental study of lymph microcirculation in small intestine mesentery of rat in vivo are presented.

Speckle diagnostics and biomicroscopy of lymph flow in microvessels

In the present study speckle-interferometry and TV intravital biomicroscopy techniques has been proposed for the analysis of microcirculatory parameters. The power spectra of fluctuation of intensity, scattered by these vessels, have a complicated shape. The mean value of first spectral movement M1 (which is assumed to be directly proportional to average velocity) in lymphatics with spontaneous contractions differ from vessels without phasic activity. We register two types of histogram of M1 in contracting and non-contracting vessels. The phasic contractions may be caused by the modification of lymph flow in microvessels and/or by the changes of the speckle signal values. An application of lymphotropic drugs (staphylococcal toxin, N-nitro-L-arginine and dimethyl sufoxide) on the lymph microvessels has been investigated. The study of lymph flow by two methods (intravital TV biomicroscopy and speckle-interferometry) allows to determine the ways of the action of vasoactive drugs on lymph flow.

Monitoring of lymph flow in microvessels by biomicroscopy and speckle-interferometry

In the paper lymph flow in microvessels by two methods in norm and under influence of vasoactive drugs: N-nitro-L- Arginine (L-NNA, 10-4M and dimethyl sufoxide (DMSO, 30%) was studied. We measured absolute linear flow velocity by microscopic method and parameter proportional to velocity (M1) using the speckle-interferometry. Also other parameters of lymph and blood microcirculation were measured. The lymph flow differs from blood flow. The average flow velocity for the lymphatics is more than for the blood microvessels. The negative correlation between blood flow velocity and diameter of vessel absents in lymphatics. The phase contractions contribute to the lymph flow. The M1 in contracting lymphatics are of the same values in different vessels. But the non-contracting microvessels has very varying indexes of M1. Probably the wall movements during phasic contractions led to the change of speckle signals. The action of vasoactive drugs (L-NNA and DMSO) stimulates the lymph flow and phasic activity in microvessels of rat mesentery. The effects of L-NNA and DMSO on diameters are different. The constriction of microvessels prevailed at the DMSO application. The dilatation dominated at the L-NNA action.

Analysis of lymph flow in microvessels by biomicroscopic and coherent optical methods

The lymph flow velocity in microvessels of rat mesentery was investigated by using biomicroscopic manual frame-by-frame technique with image processing system and speckle- interferometrical method. Lymph flow was observed in the majority of lymphatics. Lymph flow was registered in microvessels with phasic contractions and functioning valves. The lymphocytes motion in flow was measured. It was established that mean lymph flow velocity increased in vessels with phasic contractions and moderate concentration of lymphocytes in flow. The application of speckle- interferometry allowed us to estimate lymph flow on the whole with all stops, the increases and decreases of flow velocity. The parameters both of changes of a mean velocity and of spatial-temporal velocity distribution in lymph flow were calculated. Temporal changes of the parameter V showed a shuttle-type character of lymph flow velocity.

Imaging of lymph flow in single microvessels in vivo

In this study parameters of lymph microcirculation are investigated. The microcirculation was studied on small intestine mesentery in norm and during Dimethyl sulfoxide (DMSO) application. The direct measurement of lymph flow velocity (parameter V) in individual microvessels was based on the technique of light intravital videomicroscopy. The first spectral moments of Doppler signal, characterizing the mean velocities of lymph flow in microvessels (parameter M1), were measured by speckle-interferometrical method. Simultaneously, diameters of lymph microvessels as well as parameters of phasic contractions and valve function of lymphatics were registered. The value of V was very changeable; the mean V was equal to 270+/- 24micrometers /s. The M1 was the varying characteristic of the lymph flow too. The temporal dynamic of M1 was reflected alternating- translation motion of lymph flow. DMSO application during 15 min caused the constriction in a majority of lymphatics and the phasic contractions. DMSO induced lymphostatis in 20% of cases. But the other microvessels responded to the rise of lymph flow velocity. These changes led to the stimulation of drainage function of lymph microcirculation function.