Optical assessment of recovery of tissue blood supply after removal of externally applied pressure

The authors use photoelectric plethysmography to determine the external occlusion pressure for blood vessels in human tissue in vivo. Three wavelengths are employed; 950 nm (infra-red), 640 nm (red) and 583 nm (yellow). Each probe is applied in turn to one finger of each subject. Pressure is applied, using a neonatal blood pressure cuff, to the finger via the probe. This pressure is increased linearly to 20 kPa (150 mmHg) over 15 s and then decreased linearly to zero over 15 s. The pressure at which perfusion returns is obtained for four repeat measurements at each wavelength. The mean (±standard deviation) occlusion pressures for all 13 subjects investigated are 7.1(±1.9) kPa for infra-red, 6.3(±1.7) kPa for red and 5.8(±1.8) kPa for yellow. The pressure is 0.79(±0.83) kPa lower for red compared with infra-red (P<0.01), 0.54(±0.60) kPa lower for yellow compared with red (P<0.002) and 1.3(±1.0) kPa lower for yellow compared with infra-red (P<0.005). The reduced penetration of shorter optical wavelengths can be used to detect the lower occlusion pressures of the smaller blood vessels nearer the skin surface.     

Interstitial fluid pressure in canine gastric mucosa.

Guyton's capsules were implanted in the submucosa of the gastric corpus of dogs. The pressure of the fluid inside the capsule (ICP) was measured between 12 and 42 days later after mounting the piece of the corpus in a Plexiglas chamber. The capsule was always filled with saline. In two out of three experiments, the ICP did not change significantly when the saline was replaced by isotonic glucose or blood plasma. Changes of pressure exerted on the surface of the stomach were accurately monitored by the ICP recordings. Changes of circulation produced by compression of the artery or the vein connected to the piece of mucosa, or by intra-arterial injections of epinephrine, norepinephrine, isoproterenol, or hypertonic mannitol, modified the ICP as predicted by Starling's law of capillary filtration. Spontaneous activity of the gastric muscles or the activity, which followed intra-arterial injections of acetylcholine, prostigmine, or histamine, changed the ICP significantly. Intra-arterial atropine usually decreased the ICP by 3--5 mmHg. The mean value of the ICP in 49 animals was 0.53 +/- 0.34 mmHg (SEM); it was negative in 43% of the experiments.     

Degradation of cartilage in contact with soft tissue

Observations have been made on histological changes in femoral-head articular cartilage transplanted into soft tissue in rats under a variety of conditions. Articular cartilage was implanted either whole or minced. Implants were made into deflated subcutaneous air pouches with or without an inflammatory irritant and into normal subcutaneous tissue. Cartilage-matrix loss occurred in four patterns: marginal zone encroachment, loss of metachromatic staining without loss of tissue mass, surface invasion and lacunar enlargement and coalescence. The presence of an inflammatory reaction had no discernible effect on loss of cartilage matrix. Changes at the marginal zone preceded changes at the centre. Loss of metachromatic staining without loss of tissue mass occurred in areas of chondrocyte death. Surface invasion was not affected by the viability of the underlying chondrocytes. Surface invasion occurred earliest in cartilage transplanted into subcutaneous tissue, and latest in cartilage implanted into air pouches inflamed with carrageenan. The onset of surface invasion appeared to be dependent on soft-tissue adhesion to the cartilage surface. Mincing of cartilage was associated with an increase in surface invasion in the deeper cartilage zone with large lacunae but not in the superficial zone with small lacunae. Occasional cut surfaces showed outgrowth of new cartilage matrix. These observations on artefactual modes of cartilage degradation may assist in analysing the critical steps in cartilage degradation in arthritic joints.     

Interstitial fluid pressure in the isolated perfused rabbit lung

WIIG, H., OPDAHL, H., NICOLAYSEN, A. & NICOLAYSEN, G. 1985. Interstitial fluid pressure in the isolated perfused rabbit lung. Acta Physiol Scand 125 , 601–607. Received 10 March 1985, accepted 9 May 1985. ISSN 0001–6772. Department of Physiology, University of Bergen and Institute of Physiology, University of Oslo, Norway. Interstitial fluid pressure was measured in nine isolated perfused rabbit lungs with the servonull micropipette method. Bevelled glass micropipettes, with tip diameter 2–6 μm (o.d.) were inserted 2–6 mm into the left lung. At alveolar pressures of 3 to 5 cm H₂O we found mean interstitial fluid pressures of 1.0 (SD 1.0) and 1.6 (SD 1.0) cm H₂O relative to pleural pressure in the upper (n = 19) and lower (n = 21) lobes respectively. The vertical distance between the measuring sites in the upper and lower lobes was about 3 cm. Net filtration caused by elevated left atrial pressure caused practically no change in interstitial fluid pressure. Increased alveolar pressure either increased or decreased interstitial fluid pressure. The measured pressures probably represent interstitial fluid pressure in alveolar junctions or in the interstitium around small pulmonary arteries or veins. We conclude that interstitial fluid pressure in these sites is between alveolar and pleural pressure, and that it is only moderately affected by changes in alveolar pressure. The interstitial compliance appears to be high and there seem to be little or no vertical gradients in interstitial fluid pressure within the lung.     

Transmission of externally applied negative pressure to the underlying tissue. A study on the upper arm of man

The transmission to the underlying tissue of externally applied negative pressure (2-50 mmHg) was studied in 15 male volunteers on a segment of the upper arm 8 cm in length enclosed in a clear plastic cylinder sealed hermetically against the skin. Pressure recordings were obtained from the anterior and posterior tissue compartments from sites along the entire tissue segment exposed to negative pressure at depths from the skin surface ranging from 5 to 62 mm. Reduction of pressure in the cylinder caused rapid decline, and cessation of external negative pressure rapid recovery, of tissue pressure. In the steady-state phase of negative tissue pressure, the applied external pressure change was in the great majority of experiments transmitted fully or almost fully to the tissue, regardless of from which position along the tissue segment and from which tissue depth pressure was recorded and regardless of the magnitude of the applied negative pressure. The described findings suggest that a defined reduction of atmospheric pressure leads to a similar alteration of vascular transmural pressure and that the technique of external negative pressure can be used for not only qualitative but also quantitative studies of local circulatory reactions evoked by such transmural pressure changes.     

Model of interstitial pressure as a result of cyclical changes in the capillary wall fluid transport.

Reported interstitial pressures range from -8 to +6 mm Hg in different tissues and from <-20 mm Hg in burned tissue or more than +30 mm Hg in tumors. We have tried to link interstitial pressure to the here proposed cyclical changes in the fluid transport across the capillary wall.In the presented model interstitial pressure is considered as an average of pressures in numerous pericapillary spaces. A single pericapillary pressure is a dynamic difference between the net outward (hydraulic pressure+interstitial colloid osmotic pressure) and inward (plasma colloid oncotic pressure) forces. Hence, dominating net outward forces would result in a positive pericapillary interstitial pressure, while stronger inward forces would produce negative pressures in the pericapillary space. All interruptions of blood flow leave some blood in capillaries with a normal oncotic pressure and no hydrostatic pressure that might act as a strong absorber of interstitial fluid until the blood flow is reestablished.Model assumptions for the systemic circulation capillaries include (a) precapillary sphincters can almost entirely stop the capillary flow, (b) only a minority of sphincters are normally open in the tissue, and (c) hydrostatic pressures in unperfused capillaries are similar to the pressures at their venous ends.The key proposal is that capillaries with closed precapillary sphincters along their entire length have low hydrostatic pressure of 10 to 15 mm Hg. This pressure cannot force filtration, so these capillaries reabsorb interstitial fluid from the pericapillary space along their entire length. In the open capillaries, hydrostatic pressure filtrates fluid to the pericapillary space along most of their length. Fluid enters, moves some 20 or 30 micrometers away and back to be reabsorbed at the same point. Closed periods are periods of intense fluid reabsorption, while the short open periods refill the space with fresh fluid. It can be calculated that subcutaneous tissue interstitial pressure values might develop if the closed periods are 1.14 to 2.66 times longer than the open periods. Positive interstitial pressures observed in some organs might develop if open periods are longer than the closed periods.High interstitial colloid pressure in lungs makes both perfused and unperfused capillaries absorptive, resulting in more negative values of lung interstitial pressure. The same model is used to explain interstitial pressure values in tumors, burned tissue and intestinal villi.     

Particulate dermal matrix as an injectable soft tissue replacement material

Products currently used as injectable soft tissue replacement materials in the dermatologic, plastic and reconstructive, and urological fields exhibit several shortfalls including reactivity, migration, rapid degradation, and necessity of a donor site. This study examines the feasibility of providing a particulate acellular human dermal matrix for injection as a soft tissue replacement material that addresses many of these issues. Animal feasibility studies tested differences in implant performance related to processing techniques, matrix concentration, and volume of the collagen matrix to be injected. Results demonstrated that processing techniques that involve shearing and tearing of the dermal collagen matrix resulted in frayed and damaged collagen bundles and led to rapid resorption or loss of the implant, when injected subcutaneously in a rat model. Processing the collagen matrix in liquid nitrogen resulted in less damage to the collagen matrix and exhibited longer persistence, when compared to the damaged collagen matrix. This particulate matrix also exhibits rapid repopulation by host cells that should enhance revascularization and remodeling. The particulate nature of this processed dermal matrix allows for easy delivery of concentrations up to 330 mg/mL, which exceeds that of other currently used products. This increased concentration should allow for decreased need of "overcorrection" and repeated injections.     

Mutagen sensitivity as an indicator of soft tissue sarcoma risk.

The etiology of soft tissue sarcoma is poorly understood. Exposure to environmental chemicals may play a role, but the data are not clear. We compared a group of soft tissue sarcoma patients with healthy controls to determine whether the mutagen sensitivity assay, a simple chromosome aberration assay using the radiomimetic bleomycin, might be useful to identify patients at risk for soft tissue sarcoma. Patients with a diagnosis of soft tissue sarcoma at Memorial Sloan-Kettering's outpatient clinic signed informed consent and donated 30 ml of blood. Controls were selected from the general population of Connecticut by random digit dialing. Unrepaired DNA damage was assessed for 100 metaphase spreads for each individual, with the number of breaks in chromatids being counted as breaks per cell (b/c). The 20 cases with soft tissue sarcoma had 1.03 mean b/c and the controls had 0.88 b/c (P = 0.16). Patients with soft tissue sarcoma were 5.7 times more likely to be mutagen sensitive than controls (P = 0.01), as determined after dividing subjects into sensitive or not sensitive groups based on the median b/c among controls. As mutagen sensitivity has been shown to be associated with a number of cancers and appears to reflect genetic susceptibility, this assay may be an appropriate biomarker for radiation sensitivity or it may be a marker of susceptibility to soft tissue sarcoma. Larger studies should be undertaken to assess these possibilities.     

Interstitial fluid pressure correlates with intravoxel incoherent motion imaging metrics in a mouse mammary carcinoma model

The effective delivery of a therapeutic drug to the core of a tumor is often impeded by physiological barriers, such as the interstitial fluid pressure (IFP). There are a number of therapies that can decrease IFP and induce tumor vascular normalization. However, a lack of a noninvasive means to measure IFP hinders the utilization of such a window of opportunity for the maximization of the treatment response. Thus, the purpose of this study was to investigate the feasibility of using intravoxel incoherent motion (IVIM) diffusion parameters as noninvasive imaging biomarkers for IFP. Mice bearing the 4T1 mammary carcinoma model were studied using diffusion‐weighted imaging (DWI), immediately followed by wick‐in‐needle IFP measurement. Voxelwise analysis was conducted with a conventional monoexponential diffusion model, as well as a biexponential model taking IVIM into account. There was no significant correlation of IFP with either the median apparent diffusion coefficient from the monoexponential model (r = 0.11, p = 0.78) or the median tissue diffusivity from the biexponential model (r = 0.30, p = 0.44). However, IFP was correlated with the median pseudo‐diffusivity (D_p) of apparent vascular voxels (r = 0.76, p = 0.02) and with the median product of the perfusion fraction and pseudo‐diffusivity (f_pD_p) of apparent vascular voxels (r = 0.77, p = 0.02). Although the effect of IVIM in tumors has been reported previously, to our knowledge, this study represents the first direct comparison of IVIM metrics with IFP, with the results supporting the feasibility of the use of IVIM DWI metrics as noninvasive biomarkers for tumor IFP. Copyright © 2011 John Wiley & Sons, Ltd.     

Noninvasive sacral chordoma presenting as a benign soft tissue mass

In this case report, we describe a sacral chordoma, which had an atypical presentation as a mobile, encapsulated, benign soft tissue mass. The patient was asymptomatic, except for the slight enlargement of this lesion. Biopsy of this mass showed a lobulated tumor with bland neoplastic cells in a rich myxoid matrix with the classical immunohistochemical profile of chordoma. Opposite to this classical histological picture of chordoma, the imaging studies (computed tomography and magnetic resonance imaging) could not find any sacral involvement or lytic destruction. Surgical excision of this chordoma confirmed all preoperative findings and diagnoses, showing an encapsulated mass in the sacral soft tissue that has not invaded into the sacrum. This chordoma originated from the sacrococcygeal joint and grew parallel to the sacrum and below the skin. At the same time, histological sections and immunostains reconfirmed diagnosis of chordoma.     

Changes in the human electrocardiogram on breathing oxygen under pressure and their relationship to a compensating pressure applied externally to the body (vector analysis)

Summary Two series of observations were made in which the atmospheric pressure was reduced to a value corresponding to an altitude of 20,000 m. In the first, a study was made of the effects of a counter pressure applied externally to the body; in the second series the pressures were applied to separate areas of the body. When the excess pressure in the lung reached 136 mm Hg, and when an equal counter pressure was applied externally, the electrical axis and cardiac vectors deviated to the right. Variations of the external pressure up to 50 mm Hg applied while the intrapulmonary pressure is held constant, do not by themselves cause any significant changes in the ECG. When the pressure applied to the abdomen and thighs is insufficient, the cardiac vectors diminish, and circulatory disturbances occur. Vector analysis of the ECG shows that during respiration under increased pressure, the first changes occur in the right heart.(Presented by Active Member AMN SSSR, V. V. Parin) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 50, No. 12, pp. 7–11, December, 1960     

Grading of soft tissue sarcomas: necrosis as a determinant of survival

All cases of sarcomas of soft tissue occurring in males age 20-79 in Western Washington from 1981 to 1984 were studied with respect to the influence of multiple clinical, gross, and histologic parameters in predicting survival. Among histologic parameters studied, a strong and statistically significant association of necrosis of more than 15% of the tumor with death was observed. This effect was seen even when controlling for the influence of histology, site, stage of disease, and other factors. It is concluded that necrosis can serve as a prognostically relevant criterion for separating aggressive (nongrade 1) soft tissue sarcomas into intermediate grade (grade 2) and high grade (grade 3) tumors.     

A method for a quantitative determination of changes in tissue volume as a result of perfusion fixation

A method for quantifying changes in volume of tissue as a result of perfusion fixation is described. This is achieved by setting standards into the tissue in vivo and in situ by applying dyes to the intact tissue at known distances. Immediately after perfusion the distances of the dyes are macroscopically measured and the comparison between the corresponding distances before and after perfusion enables a quantification of the alteration of the tissue. The total error of this method is approximately 0.5-0.8% (linear).     

Salmonella Michigan soft tissue infection in an immunocompromised child

A rare case of soft tissue infection due to Salmonella Michigan in an immunocompromised child is reported. The same organism was isolated from a tortoise kept in the home. Immunocompromised patients are especially susceptible to reptile-associated salmonellosis and should be advised appropriately.     

Intranuclear filaments in a soft tissue sarcoma

Intranuclear filaments aggregating into rodlike structures were found in cells of an undifferentiated soft tissue sarcoma in a child. Similar structures have been uncommonly described in human neoplasms, and uncertainties exist concerning the nature of the inclusion bearing cells in previous reports. The filaments were found to be resistant to mild trypsin digestion. Review of the pertinent literature indicates that these structures may represent the structural manifestation of a highly specialized functional state, rather than a degenerative phenomenon or an artifact. A certain selectivity of occurrence has also been noted. It is therefore plausible to speculate that intranuclear filaments may eventually constitute a morphologic criterion of interest for new tumor classifications.