4, 5. Two substances having the property of causing convulsions, one having the power of contracting the pupils. The composition of both is unknown.
6. A substance which produces heat by diminishing heat production—possibly a coloring matter. That coloring matters are absorbed by charcoal and that urine thus decolorized is rendered less toxic are no proof that the coloring matters themselves are responsible for this toxic action. There is no doubt that numerous alkaloidal bodies possessing a high molecular weight are precipitated by means of carbon or charcoal, and to these bodies may be attributed a portion of that toxic action previously considered as due to coloring matters.
7. Potassium salts, which are really convulsing agencies, are the most toxic perhaps of any of the poisons contained in the urine. Chloride of potassium, for instance, is toxic at 18 Gm. for every kilo of animal.
Salivation and myosis, as well as diarrhea, are often noticed in so-called uremia. In that form known as hepatic uremia, when the liver no longer forms urea, the kidneys scarcely act. In other words, if urea is no longer present in the body, the kidneys are deprived of their principal stimulation to physiological activity. Consequently urea, for so long a time the bugbear of physicians, is shown to be most dangerous when absent. When urea is deficient, blood serum or water in which the other toxic substances are dissolved should be withdrawn. This is best done by venesection, whose value in so-called uremia experience amply corroborates. When kidney activity ceases, intoxication is likely to be produced by potassium salts. Ptomains, amido bases, etc., are proved to be present in normal urine and are known to produce toxic effect. These ptomains increase enormously in pathological urines, and to this increase, rather than to that of potassium and coloring matters (which remain fairly constant), may be attributed the higher toxicity of pathological urine. In certain cases, however, as in that of jaundice, the toxicity of the urine is partly due to decomposition of tissue cells, whereby potassium salts and organic decomposition products are liberated and excreted in the urine. The toxicity of the urine also increases with the increase of indican, which is indirectly a product of intestinal fermentation.
The osmotic pressure of the blood has much to do with the general subject of auto-intoxication, since it surrounds and permeates all the organs of the body, which are necessarily in equilibrium with it. Their individual cells functionate, then, in accordance with it, and variations in such pressure must affect their activities. It is a special function of the kidneys to eliminate enough of the accumulated metabolic products in the blood to keep this osmotic pressure at its normal. Should investigation or symptoms of disease show a wide divergence from this standard, the inference is plain, i. e., that there is renal insufficiency from impairment.
This test may be made with a small amount of blood by cryoscopy (determination of freezing point). So, too, a determination of electrical conductivity may, in a similar way and for a similar purpose, be made of clinical value. Unfortunately, these investigations are not exactly simple in character, and are not available outside of well-equipped hospitals.
Correct performance of hepatic function is also necessary that surgical cases may progress without disturbance. Bile escapes direct absorption by the blood, but not all contact with it, since in the intestine it is in contact with mesenteric capillaries, but must pass again through the liver, which takes it up again and pours it once more into the intestine.
Bile in the blood is always dangerous, although its toxicity is much smaller than has been supposed. Of all the bile thrown out into the duodenum, we are only able to account for about one-half. Its coloring matter and biliary salts are metamorphosed. Yet in certain morbid conditions bile, as such, may be reabsorbed in the liver along the margin of the hepatic cells. In these cases, if the kidneys remain permeable, auto-intoxication is simply threatened; if they have ceased to be permeable, actual auto-intoxication is the result.
Putrefaction of intestinal contents affords another source of auto-intoxication. This comes both from imperfect metamorphosis of food and from bacterial infection. Here the conditions are most favorable. Nitrogenous substances become peptonized, and peptones form the best culture media for microbes. Water is present in sufficient quantities, and a constant temperature of 37° C. is maintained. The digestive tube is always open, and invaded at frequent intervals. By such mechanism are formed those products whose effects are revealed in the so-called putrid fever of Gaspard. Brieger has shown that alkaloids are developed during the act of peptonization. Fecal matter contains also excretin, whose toxicity has been amply proved, and several other alkaloidal substances, soluble in various media, varying in toxicity. The potassium and ammonium salts contribute largely to the toxicity of feces; bile also, but in lesser degree. It has been shown that the aqueous extract of putrid matter is very toxic, while that of fecal matter is otherwise.
The most serious features of the conditions grouped under the heading of Bright’s disease are their so-called uremic features. These happen at the period when retention of toxic products is peculiarly harmful. As long as the urine is ample in amount and density—i. e., containing enough toxic materials in solution—there is no danger of intoxication. But when it no longer eliminates in twenty-four hours what it should, then we see the chronic and paroxysmal nervous accidents, the edemas, fluctuations of temperature, etc. Oliguria with urine of increasing density and general edema of the tissues may be noticed, although the other secretions continue natural and the tongue moist. As long as the normal amount of solids is eliminated, this form of “uremia” may be due to mere accumulation of water and may not be serious. Ordinarily, uremic patients are those whose urine has lost its toxicity. Usually on the day in which so-called uremic accidents happen the urine quite ceases to be toxic and is scarcely more so than distilled water. Urea alone is not to be held guilty for this condition. In order to kill a man with urea it would require the quantity which he makes in sixteen days. Nevertheless, it may become harmful after undergoing transformation into ammonium carbonate or other substances.