STUDIES ON EXPERIMENTAL HYPERTENSION : III. THE PRODUCTION OF PERSISTENT HYPERTENSION IN MONKEYS (MACAQUE) BY RENAL ISCHEMIA

Persistent elevation of systolic and diastolic blood pressure due to renal ischemia has been produced in monkeys (macaque) by the same method previously used for this purpose in dogs.     

STUDIES ON EXPERIMENTAL HYPERTENSION : VII. THE PRODUCTION OF THE MALIGNANT PHASE OF HYPERTENSION

The production of the acute malignant phase of experimental hypertension has been accomplished in seventeen dogs. The method used to produce this type of hypertension was the same as for the benign type (4), namely, constriction of the main renal arteries, or the equivalent, constriction of the aorta above the origin of both main renal arteries, but the constriction was especially severe. The malignant phase in the animals was characterized by hypertension, terminal renal insufficiency and the development of petechiae and larger hemorrhages in many internal organs, especially the alimentary tract. These were due to dissecting hemorrhage through, or rupture of, the wall of severely hyalinized or necrotic arterioles, or rupture of capillaries. Hyalinization and necrosis of arterioles were more severe and more widespread in animals that had a period of benign hypertension before the onset of renal insufficiency. In animals with a previous long period of benign hypertension, thickening of the media also occurred in arterioles, with or without hyalinized intima. Elevation of blood pressure (mechanical factor) and renal insufficiency (humoral factor) are at least two of the necessary conditions for the development of the necrotic arterioles and hemorrhages. Necrotic arterioles and hemorrhages have not yet been observed in animals that have had very high blood pressure for years without renal insufficiency, nor in animals with azotemia, due to removal of both kidneys, but without hypertension. Hyalinized retinal arterioles have been observed in dogs with persistent hypertension and with moderate or no disturbance of renal function. That ischemia is not the cause of the necrosis of the arterioles is shown by their absence from the ischemic kidneys of the dogs and their widespread presence in other organs that were not ischemic. These experiments show that the necrotic arterioles and hemorrhages are secondary to and not the primary cause of the malignant phase of hypertension.     

STUDIES ON EXPERIMENTAL HYPERTENSION : I. THE PRODUCTION OF PERSISTENT ELEVATION OF SYSTOLIC BLOOD PRESSURE BY MEANS OF RENAL ISCHEMIA

These experiments indicate that, in dogs at least, ischemia localized to the kidneys is a sufficient condition for the production of persistently elevated systolic blood pressure. When the constriction of both main renal arteries is made only moderately severe in the beginning, the elevation of systolic blood pressure is unaccompanied by signs of materially decreased renal function. In this respect the hypertension in these animals resembles the hypertension which is associated with so called benign nephrosclerosis in man. Subsequent increase of the constriction of the main renal arteries does not materially damage renal function, probably because of adequate development of accessory circulation. More delicate methods for detecting a change may yet prove that some damage does occur. Almost complete constriction of both main renal arteries, from the beginning, results in great elevation of systolic blood pressure which is accompanied by severe disturbance of renal function and uremia. This resembles the type of hypertension which is associated with so called malignant nephrosclerosis, in the sense of Fahr (17). In several of the animals with persistent elevation of systolic blood pressure, anatomical changes were observed in the glomeruli, vessels and parenchyma of the kidneys which are most probably directly referable to the ischemia. It is hoped that these investigations will afford a means of studying the pathogenesis of hypertension that is associated with renal vascular disease.     

STUDIES ON EXPERIMENTAL HYPERTENSION : II. THE EFFECT OF RESECTION OF SPLANCHNIC NERVES ON EXPERIMENTAL RENAL HYPERTENSION

Excision of the thoracic portion of the splanchnic nerves and the lower four dorsal sympathetic ganglia on both sides failed to prevent the development of persistent hypertension which, in dogs, follows the production of renal ischemia by partial clamping of the renal arteries (1). In dogs with this type of experimental renal hypertension existent for varying lengths of time (up to about 4 years), excision of the splanchnic nerves and the lower four dorsal sympathetic ganglia failed to effect any degree of permanent lowering of the blood pressure. For the dog, at least, these results tend to minimize the importance of the splanchnic vasomotor mechanism in the pathogenesis of renal hypertension. This is in agreement with the conclusions of Prinzmetal and Wilson (6) and of Pickering (7) about the part played by the vasomotor system in human hypertension. It is also in agreement with the work of Page (8), and of Collins (9), who showed that in dogs excision of the extrinsic renal nerves alone does not prevent experimental hypertension due to renal ischemia. Although the results of this investigation fail to give experimental support for the operation that is being practised on human beings with hypertension, yet they do not necessarily controvert the reports of beneficial effects in some cases of human hypertension. Further study of the effects on man is necessary before the results of this operation can be adequately evaluated.     

STUDIES ON EXPERIMENTAL HYPERTENSION : XX. THE BIOASSAY OF RENIN

A simple, rapid method for the bioassay of renin has been presented. Reliable and consistent results are obtained by this method whereby an arbitrary dog unit of renin has been established. The response of normal unanesthetized dogs to renin is independent of the body weight of dogs weighing between 10 and 25 kilos. An estimate of potency of renin per kilo of body weight of the test animals is therefore not only unnecessary but misleading. A dog unit of renin has been defined as that amount which raises the blood pressure at least 30 and not more than 35 mm. Hg within 3 minutes in at least three unanesthetized dogs. The potency is expressed as dog units of renin per cubic centimeter. The determination of the amount of renal substance represented by a cubic centimeter of extract and the number of dog units per cubic centimeter give an estimate of the yield of renin which can be expressed as dog units of renin per gram of original renal tissue. By determination of the number of dog units per cubic centimeter and the amount of nitrogen in milligrams per cubic centimeter in any renal extract the purity of the renin can be determined and expressed as dog units of renin per milligram N. The establishment of a standard method for the bioassay of renin is considered highly desirable and the method outlined in this paper is suggested for this purpose.     

STUDIES ON EXPERIMENTAL HYPERTENSION : XXI. THE PURIFICATION OF RENIN

1. Extraction of finely ground fresh hog kidney with distilled water adjusted to pH 7.8 with sodium hydroxide, followed by successive treatment, as described, with trichloroacetic acid and acetone, gives renin in good yield of a purity suitable for physiological studies and a good starting material for further purification. It contains 15 dog units per mg. N. 2. Further successive purification of this material with ethyl alcohol and ammonium sulfate gives a preparation containing 130 dog units per mg. N. The purest preparation hitherto reported (15) contained 16.0 to 20.8 units per mg. N. Preliminary Tiselius electrophoresis studies suggest homogeneity, but further studies to establish purity are in progress. 3. The properties of the most purified renin indicate that it is a protein. Its chemical and physiological properties correspond to those of the material in crude renal extract which induces an elevation of blood pressure when it is injected intravenously.     

STUDIES ON THE RENAL ARTERIAL BLOOD PRESSURE AND THE METABOLISM OF KIDNEY TISSUE IN EXPERIMENTAL HYPERTENSION

1. In the hypertension which accompanies constriction of the renal arteries, there is no constant relationship between the height of the general systemic arterial pressure and the pressure in the renal artery distal to the point of constriction. The hypertension may persist even though the renal arterial pressure returns to or almost to the control level. 2. Studies on the renal blood flow and oxygen consumption following subtotal nephrectomy were abandoned because of inability to produce hypertension in dogs by this method. It is suggested that the mechanism of the hypertension following renal arterial constriction (dogs) and that following subtotal nephrectomy (rats) may not be the same in the two instances. 3. Studies on isolated renal cortical tissue of dogs and of rabbits following renal arterial constriction and subtotal nephrectomy showed that there is not necessarily a diminution in the capacity of the tissues of hypertensive animals to use oxygen.     

STUDIES ON EXPERIMENTAL HYPERTENSION : X. THE OXYGEN CONSUMPTION OF THE ISCHEMIC KIDNEY

The consumption of oxygen by slices of renal tissue of the rabbit was studied by means of the Warburg manometric method. The ischemic kidney of the rabbit shows a definite diminution of oxygen consumption, compared with the normal kidney.     

EXPERIMENTAL STUDIES ON DIABETES : SERIES I. PRODUCTION AND CONTROL OF DIABETES IN THE DOG. 3. EFFECTS OF PROTEIN DIETS.

No specific differences were observed between the glycosuric effects of different kinds of protein. Other incidental observations were noted in connection with the records of individual animals. General conclusions are deferred to the close of the series.     

EXPERIMENTAL STUDIES ON DIABETES : SERIES I. PRODUCTION AND CONTROL OF DIABETES IN THE DOG. 1. GROSS ANATOMIC RELATIONS OF THE PANCREAS AND DIABETES.

1. The injurious effects of excessive carbohydrate diet are demon strable in partially depancreatized dogs, in the same manner as in human patients. With severe diabetes there is rapid progress of emaciation and weakness and early death. 2. With milder diabetes, there is frequently a transitional state following operation, when the fate depends on the diet. If the tolerance is spared for a time, recovery sometimes occurs to such extent that diabetes cannot be produced by any kind or quantity of feeding, but only by removal of a small additional fragment of pancreatic tissue. The proper degree of carbohydrate overfeeding is important in this early period for producing the most useful type of diabetic animals; namely, those having good digestion and general health combined with a permanent lowering of assimilative power, like the condition of human patients. 3. In the early stage, glucose is more powerful than starch in producing diabetes, and animals which are progressing toward complete recovery on starch diet can be sent into hopeless diabetes by admix ture of glucose. The difference seems to be merely of the rate of absorption, and indicates that a rapid flood of carbohydrate is more injurious to the pancreatic function than a slow absorption. When ever permanent diabetes is present, so that complete recovery is impossible, starch brings on glycosuria more slowly than sugar, but just as surely. The difference in time in different cases amounts to days, weeks, or months. The clinical lesson from such experiments is that even if a patient becomes free from glycosuria on withdrawal of sugar only, nevertheless other foods should also be limited. 4. No significant differences were observed between the assimilation of different starches, or any extreme lowering of the carbohydrate tolerance by proteins, such as alleged by certain writers in connection with the "oatmeal cure." 5. Repair of traumatic inflammation and hypertrophy of the pancreas remnant have been mentioned incidentally as the basis of the early tendency to recovery, and also hydropic degeneration of Lang erhans islands as an accompaniment of the lowering of tolerance by excessive diet. These are believed to have their parallels in human cases, and are to be described more fully hereafter.     

STUDIES ON EXPERIMENTAL HYPERTENSION : XIV. THE EFFECT OF INTERMITTENT RENAL ARTERIAL OCCLUSION ON THE BLOOD PRESSURE OF THE DOG

By means of a silver chain attached to a silver ring around the main renal artery, intermittent renal arterial occlusion, up to 30 minutes daily, was practiced for as long as 5 months in unilaterally nephrectomized dogs. This did not result in the development of persistently elevated blood pressure. Persistent moderate constriction of the renal artery of such animals by a silver clamp, after intermittent temporary occlusion had failed to affect the blood pressure, produced the usual rise of blood pressure, without accompanying significant impairment of renal excretory function. When the renal artery accidentally became persistently constricted to a great degree, or actually occluded, or if occlusion was deliberately produced by continuous pulling of the chain, hypertension and renal insufficiency (the malignant phase) quickly developed. The results do not lend support to the view that brief daily periods of renal ischemia from intrarenal vasospasm, or from any other cause, can produce persistent hypertension of renal origin.     

STUDIES ON EXPERIMENTAL PNEUMONIA : I. PRODUCTION OF PNEUMOCOCCUS LOBAR PNEUMONIA IN MONKEYS.

1. Lobar pneumonia has been consistently produced in normal monkeys by the intratracheal injection of minute amounts of pneumococcus culture. 2. The disease produced has been shown to be clinically identical with lobar pneumonia in man. 3. Lobar pneumonia has been produced in the monkey in one instance by experimental contact infection. 4. Normal monkeys inoculated in the nose and throat with large amounts of pneumococcus culture have failed to develop lobar pneumonia though carrying the organism in their mouths for at least a month. They have likewise failed to show any evidence of upper respiratory tract infection. 5. Monkeys inoculated subcutaneously or intravenously with pneumococcus culture have in no instance developed pneumonia, but have either died of pneumococcus septicemia or recovered without localization of the infection in the lungs.     

STUDIES ON PERSISTENT INFECTIONS OF TISSUE CULTURES : IV. EVIDENCE FOR THE PRODUCTION OF AN INTERFERON IN MCN CELLS BY MYXOVIRUSES

In previous reports of this series, it was shown that persistent infection of MCN cultures with certain myxoviruses rendered the cells insusceptible to superinfection by several cytopathogenic viruses. It was thought that production of an interferon might be the cause of this resistance and efforts to confirm this suggestion have been presented. Addition of ultraviolet-inactivated myxoviruses (mumps, Newcastle disease, influenza A, and Sendai) to MCN cultures for periods of 2 to 3 hours, followed by washing and refeeding of the cells, led to the subsequent release into the media of a substance which induced in fresh MCN cells a transitory resistance to infection by vesicular stomatitis virus, and prevented incomplete reproductive cycles of influenza A and Sendai viruses. Media containing this substance were free of detectable hemagglutinating activity and viral complement-fixing antigens. The substance was not neutralized by specific antiviral sera; it was not sedimentable by high speed centrifugation; it was not adsorbed onto red cells; but it was inactivated by trypsin. Thus, its properties matched those of the interferon described by Isaacs and his associates. A comparison of the extent of resistance induced in MCN cells by decreasing doses of ultraviolet-inactivated myxoviruses (interference test) and the protection afforded by the media removed from the cultures prior to challenge and transferred to fresh MCN tubes (interferon test) revealed that wherever interference became detectable in the cells, the media of the corresponding cultures contained some interferon. Interferon was obtained by inactivated myxoviruses also from primary cell cultures by the same techniques, but not from HeLa cells. Interferons derived from one type of culture may protect others equally well or show a certain degree of host specificity in that resistance in homologous cells may be somewhat more pronounced than in heterologous cultures. No resistance could be induced in HeLa cells by the interferon preparations employed. Interferon was detected also in MCN cultures, persistently infected with mumps virus. Its concentration was apparently too small in carrier cultures maintained as routine to be measurable. However, when the cells were grown in heavy sheets in roller bottles, and especially when the volume of medium was reduced for several days prior to harvest, interferon became readily detectable. These results strengthen the suggestion that interferon may play a decisive role in the establishment and maintenance of persistent infections in the system under study. Its nature, source, mode of action, and exact role in persistent infection remains to be elucidated.     

悦宁定治疗肾性高血压的研究

目的：探讨悦宁定（马来酸依那普利，MSD）治疗肾性高血压的作用。方法：测定46名肾性高血压患者口服悦宁定前后的血压、心肾功能、蛋白尿并予以评价。结果：口服悦宁定后，高血压的症状逐渐缓解或消失，血压由24．7±1．8／14．6±1．3kPa降到17．9±1．5／11．2±1．4kPa，血尿素氮（BUN）、血肌酐（Scr）、24h尿蛋白排泄量、分别由17．8±5．6mmol／L、428．3±158．5μmol／L、3．79±0．51g／L，降到11．5±4．9mmol／L、335．7±131．8μmol／L、1．18±0．32g／L（P＜0．01），心功能改善，E／A由＜1好转到＞1。GOT、GPT、ALP、LDH、血糖、胆固醇、三酸甘油脂无变化。结论：悦宁定是安全、高效，对肾脏和代谢无明显副作用的降压药物。     

STUDIES UPON EXPERIMENTAL PNEUMONIA IN RABBITS : VII. THE PRODUCTION OF LOBAR PNEUMONIA.

1. The production of lobar pneumonia in rabbits is dependent upon the introduction of organisms into the alveoli themselves. 2. In order to accomplish this the catheter through which they are injected must be inserted as deeply into a bronchus as possible and the culture fluid injected with considerable force. 3. Large numbers of organisms injected into the trachea just beyond the larynx set up no great changes in the lungs, even though the injection be forcible. This fact suggests the presence of a protective mechanism in the upper air passages, which, under normal conditions, prevents the penetration of organisms into the lungs. 4. If animals be subjected to cold, alcohol, and the inhalation of irritating gases, the so called secondary factors in the etiology of lobar pneumonia in man, then the injection of pneumococci into the trachea causes inflammatory changes of the upper respiratory tract and occasionally pneumonia. 5. The vagi prevent foreign material in the pharynx and upper respiratory tract from reaching the lungs. Section of one vagus may be followed by pneumonia, while section of both invariably leads to this result. 6. It is possible that the secondary factors mentioned above owe their action to their influence upon the vagus control of the upper respiratory tract.     

PRODUCTION OF ANTIRENIN TO HOMOLOGOUS RENIN AND ITS EFFECT ON EXPERIMENTAL RENAL HYPERTENSION

1. Procedures are described for the extraction and partial purification of dog renin, on a large scale, as well as for the acetylation of rat, rabbit, and dog renin. 2. Untreated homologous renin was not antigenic in rat, rabbit, or dog, but the acetylation of homologous renin made it antigenic. 3. Immunization of rats, rabbits, and dogs, with acetylated rat, rabbit, and dog renin, respectively, resulted in each case in the development of anti-renin to the homologous, untreated, as well as to the acetylated renin. 4. The progressive development of antirenin as a result of repeated, subcutaneous injections of acetylated dog renin, in a dog with experimental renal hypertension for more than 6 years, was accompanied by a correspondingly progressive fall of the mean arterial blood pressure to the prehypertensive level. This points up the important part played by the renin-angiotensin mechanism in the maintenance of the hypertension, even in the chronic phase of experimental renal hypertension.     

ANTIBODY PRODUCTION IN VITRO : I. SINGLE CELL STUDIES OF THE SECONDARY RESPONSE TO SHEEP ERYTHROCYTES

The effect of high specific activity thymidme-³H on proliferation and antibody production, using the hemolytic plaque-forming technique, by spleen cell suspensions in vitro from rabbits killed after a boost of SRC's has been studied. High specific activity thymidine-³H inhibited the proliferative ay well as the antibody response to antigen, and it was conduded that this was the result of the incorporation of radioactive ³H into the nuclei of dividing cells which were synthesizing antibody in these cultures. The stimulation of the rate of DNA synthesis by specific antigen could be correlated with the ability of antigen to maintain antibody production, as measured by the specific hemolytic plaque-forming technique, above levels found in control cultures, incubated without antigen. Radioautographic studies of PFC's in vitro showed that the majority of the cells arose from the DNA-synthesizing population of cells in these cultures, confirming the conclusions from the results of the inhibitory effects of high specific-activity thymidine-³H on PFC's. It was found that these PFC's, labeling with thymidine-¹⁴C, formed only a small proportion of all the cells labeled in this way in these cultures. The postulation was made that antigen, in vitro, provided a stimulation for cell proliferation in the responsive population of rabbit spleen cells, but that only a small proportion of this population could be induced by antigen to synthesize antibody.     

STUDIES IN EXPERIMENTAL SYPHILIS : I. THE INFLUENCE OF THE SIZE OF INOCULUM ON THE COURSE OF EXPERIMENTAL SYPHILIS IN THE RABBIT.

1. The size of the dose of the infecting material exerts an appreciable effect upon the duration of the incubation period in experimental syphilis of the rabbit. Other things being equal, the larger the dose the shorter is the incubation period. 2. The size of the inoculum was not found to exercise any marked effect upon the course of the disease as a whole. 3. In individual rabbits inoculated with minimal amounts of virus the disease may run a malignant course.     

EXPERIMENTAL STUDIES ON DIABETES : SERIES I. PRODUCTION AND CONTROL OF DIABETES IN THE DOG. 5. VARIOUS FAILURES OF DIETETIC TREATMENT,AND THEIR CAUSES.

1. Practically every detail of clinical diabetes can be reproduced in partially depancreatized animals. The resemblance is made still more exact by the susceptibility of such dogs to acidosis and coma, as will be shown in later papers, and also by the similarity of the anatomic changes in the islands of Langerhans. These animals are therefore useful test objects for a therapeutic investigation. 2. These animals at first show considerable tendency to regain assimilation, comparable to that in the early stages of most human cases of diabetes; and in some instances they recover so as to be able to endure any degree or duration of carbohydrate feeding and can be made diabetic only by removal of additional pancreatic tissue. Similar recovery in some human cases, especially after acute pancreatitis, is a probability. This recuperative tendency can be negatived by overfeeding, even without glycosuria. With duration of the diabetes the power of recuperation diminishes and practically disappears in dogs as in human patients. 3. In the absence of progressive pancreatitis or other extraneous causes, these dogs show no inherent downward tendency in their assimilation. This conclusion rests upon observations as long as 6 years from the first pancreas operation and 3 years of known diabetes. This absence of inherent progressiveness is what should naturally be expected in animals with simple resection of part of an organ, and serves further to fit them for accurate feeding experiments. 4. Every detail of the downward progress of human patients on various diets is reproduced in such animals. They lose assimilation and die most rapidly on diets rich in carbohydrate, and less rapidly on excess of other foods. The differences between sugar and starch, and between starch and protein, seem to be only those of degree and time rather than anything absolute. The important point is that, granting the absence of spontaneous downward tendencies as stated, all the different kinds and degrees of downward progress in the records of animals in this and the preceding paper are purely the results of overstrain of the internal pancreatic function by excess of food. 5. Varying degrees of success and failure in the dietetic control of diabetes are also illustrated. The benefit of the classical treatment by exclusion of preformed carbohydrate and limitation of protein is confirmed, in the prolongation of life and well-being to some extent in nearly all cases and perhaps indefinitely in some of the mildest cases. In the great majority of cases such a therapeutic result is not permanent, and downward progress is finally observed if the observations are continued long enough. In most of these cases life, strength, and assimilation can be preserved for a much longer time by a degree of undernutrition suited to the severity of the diabetes, and accomplished by limitation of fat in the diet. The permanence of such control is supported by the unimpaired or rising assimilation in experiments of 1 to 1¾ years duration, but still longer observations would be desirable. Diabetes of great severity is controllable only by correspondingly radical undernutrition. In still more severe cases glycosuria can be abolished only by a degree of undernutrition which entails final death from inanition. In the most severe cases glycosuria cannot be stopped, evidently because the assimilative power is too low to dispose of even the minimum supply of food materials; namely, that derived from the body stores in fasting. 6. A claim of saving every patient, no matter how near death, would be a preposterous one for any remedy in any disease, and the animal experiments do not support such a claim for diabetes. Also it is unreasonable to expect the actual cure of an organic deficiency by diet, and the diet treatment in animals just as in patients generally represents the sparing rather than the restoration of the weakened function. The basis of the belief in the inherently progressive tendency of severe cases of clinical diabetes is shaken by the exact reproduction of such case histories by diet in animals which are free from spontaneous downward tendencies; but there is still lack of a sufficient number of patients treated on the principle of relief of the total metabolic burden to demonstrate the absence of such inherent progressiveness in human diabetes. As described elsewhere, the principle mentioned has given encouraging results in proportion as it has received actual application in practice. The clinical problem requires the same prolonged careful control of all discoverable symptoms as in animals, and cases too severe for such control, or complicated with infections, violations of diet, etc., are on the same plane as animals in which a similar condition has been produced. Some proportion of cases, especially in young persons, will be found suitable for accurate determination of the question of whether all or most cases of severe diabetes are inevitably progressive and hopeless, and the writer looks forward to publishing such a series. Irrespective of the outcome, the raising of this question is justified by its importance. On the theoretical side, it involves both the general prognosis and the nature of the process underlying diabetes. On the practical side, it is already established that diet is at least the chief cause of downward progress, and it is important to eliminate this cause by avoiding the dietary injuries illustrated in the animal experiments.