scholarly journals THE GRADIENT OF VASCULAR PERMEABILITY

1931 ◽  
Vol 53 (2) ◽  
pp. 219-242 ◽  
Author(s):  
Peyton Rous ◽  
Frederick Smith
Keyword(s):  
Vascular Permeability ◽  
Structural Differentiation ◽  
Gradient Of Permeability ◽  
Rule Out

A steeply mounting gradient of permeability is demonstrable along the meshwork of capillaries which connects the arterioles and venules of the skin of the frog. The venules incorporated in the meshwork are even more permeable than the capillary meshes giving into them. The presence of the gradient under such differing conditions as exist along frog and mammalian capillaries enables one to rule out certain factors which might be invoked to explain it; and it is not explainable in terms of those influences generally recognized as conditioning exchange between the blood and tissues. Not improbably it results from a structural differentiation along the capillary.

scholarly journals THE GRADIENT OF VASCULAR PERMEABILITY

1931 ◽  
Vol 53 (2) ◽  
pp. 195-217 ◽  
Author(s):  
Frederick Smith ◽  
Peyton Rous
Keyword(s):  
Vascular Permeability ◽  
Skeletal Muscles ◽  
Capillary Permeability ◽  
Flight Muscle ◽  
Frog Muscle ◽  
The Other ◽  
Other Hand ◽  
Chicken Muscle ◽  
Gradient Of Permeability ◽  
Collecting System

A mounting gradient of permeability exists along the capillaries of frog muscle. In chicken muscle on the other hand none has been demonstrated; but the close-knit vascularization is arranged in duplicate in such manner that the blood runs in opposite directions through the capillaries of nearly adjacent fibres. In a flight muscle of the pigeon there exists in addition to this artifice what appears to be a special collecting system of venous capillaries. In the mammalian diaphragm indications of such a system are also to be found, and a gradient of capillary permeability like that in the other skeletal muscles is probably present. These vascular conditions are briefly considered in terms of function.

scholarly journals THE GRADIENT OF VASCULAR PERMEABILITY

1931 ◽  
Vol 54 (4) ◽  
pp. 499-514 ◽  
Author(s):  
Frederick Smith ◽  
Peyton Rous
Keyword(s):  
Vascular Permeability ◽  
Human Skin ◽  
Gradient Of Permeability

The permeability of the venules of the skin of the mouse greatly exceeds that of the capillaries. A mounting gradient of permeability exists along the further portion of the latter. The significance of these facts is discussed with relation to conditions in human skin. The cutaneous venules are differentiated for several functions besides those ordinarily attributed to them, and must be considered as specialized organs.

scholarly journals THE GRADIENT OF VASCULAR PERMEABILITY

1930 ◽  
Vol 51 (5) ◽  
pp. 807-830 ◽  
Author(s):  
Peyton Rous ◽  
H. P. Gilding ◽  
Frederick Smith
Keyword(s):  
Blood Flow ◽  
Urinary Bladder ◽  
Vascular Permeability ◽  
Muscle Fibre ◽  
Skeletal Muscles ◽  
Individual Cell ◽  
Liver Lobule ◽  
Gradient Of Permeability ◽  
Functional States ◽  
The Individual

The permeability of the capillaries in the skeletal muscles of mammals increases progressively along their course and is greatest where they pass into the least venules. The gradient of permeability is so largely independent of functional states as to give grounds for the view that it is determined by inherent local differences. Through the gradient opportunity is equalized along the capillary. In the liver lobule this object is accomplished by an artifice of arrangement whereby the blood flow past the cells is increased with their distance from the source of supply. In the urinary bladder the interlacing of capillaries, their progressive widening, and a consequent gradual slowing of the blood flow act to achieve the same end. Here a gradient of permeability has not been demonstrable. Where cells of different sorts are served by a slender capillary, their differing requirements may render unnecessary any provision to equalize their opportunities; but where shortcomings in local maintenance will reduce the efficiency of an entire fabric, as the muscle fibre, and where cells of like character live competitively along the same channel, as in the liver, some arrangement must exist to ensure an even distribution of the services rendered by the blood. In situations of the kind last mentioned the immediate environment of the individual cell, the "milieu interne" of Bernard, is not only kept as constant as possible but it must be the same, by and large, for all of the cells. The task of serving voluntary muscle is not strictly limited to the capillaries. The intrafascicular arterioles and venules act so effectively to sustain the tissue about them that where they run no capillaries are supplied.

scholarly journals THE GRADIENT OF PERMEABILITY OF THE SKIN VESSELS AS INFLUENCED BY HEAT, COLD, AND LIGHT

1932 ◽  
Vol 55 (3) ◽  
pp. 431-439 ◽  
Author(s):  
Stephen Hudack ◽  
Philip D. McMaster
Keyword(s):  
Vascular Permeability ◽  
Vessel Wall ◽  
Functional Changes ◽  
Small Vessels ◽  
Vascular Walls ◽  
Gradient Of Permeability

The mounting gradient of permeability along the small vessels of the corium is essentially unaltered by active hyperemia produced by heat, cold, or light. Only when the vascular walls are so damaged that rapid leakage ensues, as shown by the development of edema, does the permeability of the capillary web as a whole approximate that of the venules. It is plain that the normal gradient of vascular permeability depends upon the integrity of the vessel wall. The method of experiment described can be utilized for a study of the functional changes which result in the lesions due to burning and freezing.

scholarly journals THE VESSELS INVOLVED IN HYDROSTATIC TRANSUDATION

1932 ◽  
Vol 55 (3) ◽  
pp. 417-430 ◽  
Author(s):  
Philip D. McMaster ◽  
Stephen Hudack
Keyword(s):  
Venous Pressure ◽  
Vital Staining ◽  
Structural Differentiation ◽  
Small Vessels ◽  
Gradient Of Permeability

The gradient of permeability which exists along the cutaneous capillaries and venules is accentuated and broadened in scope by increasing the venous pressure moderately. Under such circumstances transudation leading to edema takes place most abundantly from the venules. The permeability of the portion of the capillary web that is near the arterioles increases only when the venous pressure rises so high as to approximate that in the arteries. Under such circumstances the gradient of permeability along the small vessels disappears, the capillaries and venules everywhere leaking fluid. The character of the vital staining developing under such circumstances indicates, like the evidence of previous work, that the cause for the gradient is to be sought in a structural differentiation.

A rapid method for the direct identification of paramyxovirus in canine CSF by ultracentrifugation and negative staining as a rule out for distemper

1990 ◽  
Vol 48 (3) ◽  
pp. 594-595
Author(s):  
W.L. Steffens ◽  
M.B. Ard ◽  
C.E. Greene ◽  
A. Jaggy
Keyword(s):  
Subacute Sclerosing Panencephalitis ◽  
Clinical Signs ◽  
Viral Disease ◽  
Etiologic Agent ◽  
Mucosal Inflammation ◽  
Worldwide Distribution ◽  
Negative Stain ◽  
Viral Particles ◽  
Systemic Manifestations ◽  
Rule Out

Canine distemper is a multisystemic contagious viral disease having a worldwide distribution, a high mortality rate, and significant central neurologic system (CNS) complications. In its systemic manifestations, it is often presumptively diagnosed on the basis of clinical signs and history. Few definitive antemortem diagnostic tests exist, and most are limited to the detection of viral antigen by immunofluorescence techniques on tissues or cytologic specimens or high immunoglobulin levels in CSF (cerebrospinal fluid). Diagnosis of CNS distemper is often unreliable due to the relatively low cell count in CSF (<50 cells/μl) and the binding of blocking immunoglobulins in CSF to cell surfaces. A more reliable and definitive test might be possible utilizing direct morphologic detection of the etiologic agent. Distemper is the canine equivalent of human measles, in that both involve a closely related member of the Paramyxoviridae, both produce mucosal inflammation, and may produce CNS complications. In humans, diagnosis of measles-induced subacute sclerosing panencephalitis is through negative stain identification of whole or incomplete viral particles in patient CSF.

Impairment Questions and Answers

1999 ◽  
Vol 4 (4) ◽  
pp. 4-4
Keyword(s):  
Symptom Validity ◽  
Validity Testing ◽  
Symptom Validity Testing ◽  
Negative Results ◽  
Tunnel Vision ◽  
Questions And Answers ◽  
Blurry Vision ◽  
Fatigue Evaluation ◽  
Choice Testing ◽  
Rule Out

Abstract Symptom validity testing, also known as forced-choice testing, is a way to assess the validity of sensory and memory deficits, including tactile anesthesias, paresthesias, blindness, color blindness, tunnel vision, blurry vision, and deafness—the common feature of which is a claimed inability to perceive or remember a sensory signal. Symptom validity testing comprises two elements: A specific ability is assessed by presenting a large number of items in a multiple-choice format, and then the examinee's performance is compared with the statistical likelihood of success based on chance alone. Scoring below a norm can be explained in many different ways (eg, fatigue, evaluation anxiety, limited intelligence, and so on), but scoring below the probabilities of chance alone most likely indicates deliberate deception. The positive predictive value of the symptom validity technique likely is quite high because there is no alternative explanation to deliberate distortion when performance is below the probability of chance. The sensitivity of this technique is not likely to be good because, as with a thermometer, positive findings indicate that a problem is present, but negative results do not rule out a problem. Although a compelling conclusion is that the examinee who scores below probabilities is deliberately motivated to perform poorly, malingering must be concluded from the total clinical context.

Case Exercise: Toxic Exposure-Related Illness: Causation, Diagnosis, and Permanent Impairment

2007 ◽  
Vol 12 (2) ◽  
pp. 4-8
Author(s):  
Frederick Fung
Keyword(s):  
Concentration Level ◽  
Treatment Plan ◽  
Toxic Exposure ◽  
Dose Response Relationship ◽  
Specialty Board ◽  
History Of ◽  
Subjective Complaints ◽  
Based Medicine ◽  
Illness Causation ◽  
Rule Out

Abstract A diagnosis of toxic-related injury/illness requires a consideration of the illness related to the toxic exposure, including diagnosis, causation, and permanent impairment; these are best performed by a physician who is certified by a specialty board certified by the American Board of Preventive Medicine. The patient must have a history of symptoms consistent with the exposure and disease at issue. In order to diagnose the presence of a specific disease, the examiner must find subjective complaints that are consistent with the objective findings, and both the subjective complaints and objective findings must be consistent with the disease that is postulated. Exposure to a specific potentially causative agent at a defined concentration level must be documented and must be sufficient to induce a particular pathology in order to establish a diagnosis. Differential diagnoses must be entertained in order to rule out other potential causes, including psychological etiology. Furthermore, the identified exposure at the defined concentration level must be capable of causing the diagnosis being postulated before the examiner can conclude that there has been a cause-and-effect relationship between the exposure and the disease (dose-response relationship). The evaluator's opinion should make biological and epidemiological sense. The treatment plan and prognosis should be consistent with evidence-based medicine, and the rating of impairment must be based on objective findings in involved systems.

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