Glycosaminoglycans of the rat renomedullary interstitium: ultrastructural and biochemical observations.

The rat renal papillary interstitum which contains abundant proteoglycans is a unique area important in renal function. These proteoglycans were studied ultrastructurally by ruthenium red fixation and staining and phosphate-buffered fixation before and after enzyme digestion. A tissue culture of rat renomedullary interstitial cells, the predominant cell of the renal papillary interstitum, was studied for its ability to synthesize proteoglycans and the proteoglycans were then analyzed. Tissue slices of whole rat renal inner medulla were also evaluated for their synthetic ability. In combination, these studies indicate that the dominant glycosaminoglycan is hyaluronic acid. The tissue culture of rat renal medullary interstitial cells synthesized glycosaminoglycans and on analysis, hyaluronic acid was found to be the chief glycosaminoglycan secreted by the renomedullary interstitial cells. Combined with the removal of the proteoglycans from tissue by leech hyaluronidase and testicular hyaluronidase, this suggests that the dominant glycosaminoglycan is hyaluronic acid. Hyaluronic acid is also synthesized by the intact papilla confirming the findings with the tissue culture. However, in addition, sulfated glycosaminoglycans were also synthesized by the intact papilla, presumably the product of the noninterstitial components of the papilla.

B2 bradykinin receptor-like binding in rat renomedullary interstitial cells.

A particulate fraction from cultured rat renomedullary interstitial cells (RRIC) was prepared for bradykinin (BK) binding studies. Incubation of three radiolabeled BK analogs, [125I-Tyr1]kallidin, [125I-Tyr5]-BK, and [125I-Tyr8]-BK, with the particulate fraction resulted in degradation of these peptides. Assay conditions which prevented hydrolysis of these radiolabeled kinins were determined. Under these conditions, direct binding studies were performed with [125I-Tyr1]kallidin (TlK) as the radioligand. BK binding affinity, apparent Kassoc. = 1.3 X 10(9) M-1, and specificity, determined with 51 BK analogs, were consistent with those expected of a B2 BK receptor.

Juxtaglomerular cells grown as monolayer cell culture contain renin, angiotensin I-converting enzyme, and angiotensin I and II/III.

A monolayer cell culture of juxtaglomerular cells (JGC) was derived from the renal cortex of neonatal rats. The JGC had the characteristics of those within the kidney, including peripheral dense bodies and myofibrils indicating a smooth muscle origin; rough ER containing fluffy material consistent with protein synthesis; a prominent Golgi apparatus for packaging granules, and granules having the characteristics of secretory granules and lysosomes. Transplants of the cultured cells into syngeneic recipients survived for 2 weeks or longer and retained the features of JGC. The JGC granules fluoresced when treated with a rabbit antibody against pure rat renin, followed by fluorescein isothyocyanate conjugated F(ab')2 fragment of goat antirabbit IgG (Fc fragment) heavy chain specific. The latter indicated the presence of renin. The JGC were lysed in the presence of DFP, captopril, leupeptin, and EDTA, and were extracted in the presence of pepstatin. The lysate contained renin activity that was inhibited by a specific renin antibody. Nonspecific proteases were excluded by the antibody and its pH optimum. Angiotensin I-converting enzyme was detected in the lysate prepared without the use of EDTA and captopril. Angiotensins I and II/III were derived from the extract by additional extractions, TLC, and RIA, using highly specific antibodies. The angiotensins were confirmed by chromatography monitored by authentic angiotensins. We concluded that the cultured JGC contained renin, angiotensin I-converting enzyme, and angiotensin I and II/III.

Cultured juxtaglomerular cells cause hypertension by secreting angiotensin.

Cultured JGC contain renin, angiotensin I, angiotensin I-converting enzyme, angiotensin II, and, by implication, the entire RAS. JGC, as transplants, appear to secrete angiotensin II/III directly into the bloodstream to cause hypertension when the renal mass is reduced. There are two main phases of the hypertensive state, an angiotensin-dependent developmental phase and a non-angiotensin-dependent maintenance phase. This model may be useful in attempts to evaluate pro-hypertensive actions of angiotensin other than those due to direct systemic vasoconstriction. Certain of these actions appear to be intrarenal and include the stimulation of sodium reabsorption, a decrease in renopapillary blood flow, the stimulation of prostaglandin synthesis, and a constraint on the antihypertensive function of the RIC.

Comparative effects of sulfones and rifampin on growth of Mycobacterium lepraemurium in macrophage diffusion chamber cultures.

A cell-impermeable diffusion chamber technique has been developed that lends itself to growth studies of Mycobacterium lepraemurium. This technique, in which the organism grows within macrophage cultures inside the chambers that are maintained on monolayer cultures of macrophages, provides a method for a strict in vitro evaluation of antileprosy drugs without the influence of a multiplicity of host factors. This system was used to compare the effect of three sulfone derivatives and rifampin on the growth of M. lepraemurium within these diffusion chamber cultures. Two sulfones, 4,4'-diaminodiphenyl sulfone and 4,4'-diacetamidodiphenyl sulfone, as well as rifampin, suppressed the growth of M. lepraemurium, but monoacetyl sulfone 4-amino-4'acetamidodiphenyl sulfone had no effect. The results indicate that the diffusion chamber technique can be used to evaluate the inhibitory effect of antileprosy drugs on the growth of M. lepraemurium. Also, the method provides for the first time a relatively rapid in vitro method for directly comparing the effects of drugs or their analogs when outside the metabolic influence of an animal host. This technique may be a useful tool for chemotherapy studies with other antileprosy compounds.

Reversal of hypertension by transplants and lipid extracts of cultured renomedullary interstitial cells.

Transplants and lipid extracts of the same monolayer tissue culture of renomedullary interstitial cells from murine renal medulla exerted a similar antihypertensive action in rats having hypertension of the sodium-volume-dependent-type. The antihypertensive action resembled that caused by lipid extracts of rabbit renal medulla and extracts of lapine renomedullary interstitial cells grown in tissue culture. The recession of the arterial pressure of the hypertensive animals usually occurred slowly and steadily to a maximum within 6 to 12 hours. On occasions, a substantial acute depressor effect preceded the slow and steady decline of the pressure. As the pressure was lowered, there was either minimal or no change in the pulse rate. The lowering of the hypertensive pressure before there was vascularization of the transplant appears to support the view that the transplanted cells secreted and/or liberated an antihypertensive substance(s) that seeped out and was absorbed by nearby capillaries and/or lymphatics and circulated and acted in the manner of a hormone. The extracted and purified lipid from the same cells as used for transplantation is proposed as a candidate for such hormonal action. Evidence is presented that minimizes the possibility of the classic renomedullary prostaglandins as this antihypertensive lipid. The findings add support to the concept that the kidney exerts a hormonal antihypertensive action that opposes the well known hormonal prohypertensive renal actions.

Functional-morphological correlates of renomedullary interstitial cells.

1. Indomethacin treatment of renomedullary interstitial cells (RIC) causes a marked increase in number and size of their lipid droplets. The anti-hypertensive function is retained. 2. After multiple passages in tissue culture, RIC lose their ability to produce an anti-hypertensive effect in hypertensive animals. Along with this functional loss, lipid droplets and a prominent cisternal system become attenuated or disappear. 3. We conclude that preservation of the lipid granule-cisternal organelle relationship is important in preservation of the anti-hypertensive endocrine function of RIC.

Anti-hypertensive lipid tissue from culture of renomedullary interstitial cells of the rat.

1. Allogenic transplants of cultured renomedullary interstitial cells exert a powerful anti-hypertensive action. The blood pressure of hypertensive animals usually drops slowly over 8-12 h whereas the pulse is unchanged or reduced. 2. Lipids derived from the cultured cells exert a similar anti-hypertensive action. 3. The anti-hypertensive action of transplanted cultured cells almost certainly results from the secretion of a substance(s) that acts in the manner of a hormone. The tissue culture lipid is a prime candidate hormone. 4. The relationship of the kidney to the hypertensive state is considered to entail pro- and anti-hypertensive actions. The pro-hypertensive actions include (a) activation of the renal pressor system (mainly renin-angiotensin), (b) failure to prevent sodium and fluid overloading because of either an injured or absent kidney or the excessive action of mineralocorticoids (mainly aldosterone). The antihypertensive actions of the kidney include (a) the relief of sodium and fluid overloading through diuresis-natriuresis and (b) the action of the reno-medullary interstitial cell hormone (the antihypertensive renomedullary hormone).

Evaluation of a red cell agglutination test for detection of Australia antigen (HG Ag).

An investigational red cell agglutination (RCA) test was evaluated for sensitivity in detecting and titering hepatitis B antigen (HB Ag) in comparison with two counterelectrophoresis (CEP) systems and a solid-phase radioimmunoassay (RIA). The RCA procedure was found to be significantly more sensitive than the CEP methods and compares favorably in sensitivity with the solid-phase RIA, detecting even lower concentrations of the HB Ag. Since the RCA test can be completed in 2 to 3 h and requires relatively inexpensive equipment, it offers a highly sensitive and rapid procedure suitable for use in blood banks to screen donors or detect low levels of antigen in serum of patients.

Growth of Mycobacterium lepraemurium in Cell-Impermeable Diffusion Chambers.

Successful growth of Mycobacterium lepraemurium has been achieved by use of a specialized diffusion chamber technique. The cell-impermeable porous chambers were maintained in animals for periods up to 50 days with and without macrophages and LM cells. A generation time of 6 to 8 days was found for the acid-fast bacilli in chambers containing macrophages when maintained in the mouse. Also, cell-free chambers maintained in the mouse gave a generation time of 11 days for M. lepraemurium. There was no doubt that chambers maintained in a susceptible host provided greater yields of bacilli than chambers maintained in a nonsusceptible host such as the guinea pig. In fact, better yields were obtained when the chambers were maintained in monolayer petri plate cultures of mouse peritoneal macrophages than when held in the guinea pig. The most pertinent observation was that living cells are not essential for growth of M. lepraemurium, and the results suggest that multiplication can occur in a cell-free environment within a susceptible host. These studies give evidence that the use of porous chambers has promising possibilities for further investigations on the cultivation of other fastidious mycobacteria.

Stabilities of dried suspensions of influenza virus sealed in a vacuum or under different gases.

Suspensions of purified influenza virus, dried to a 1.4% content of residual moisture by sublimation of ice in vacuo, were sealed in a vacuum or under different gases of high purity. The stabilities of the several preparations were determined by an accelerated storage test. Based on the times predicted for the dried preparations stored at different temperatures to lose 1 log of infectivity titer, the order of stabilities in relation to sealing in vacuum or under different gases was as follows: helium > hydrogen > vacuum > argon > nitrogen > oxygen > carbon dioxide.

Antiviral activity of carbobenzosy di- and tripeptides on measles virus.

A series of simple carbobenzoxy peptides showed high and consistent antiviral chemotherapeutic activity in cell culture. In general, greatest activity was found against the measles-distemper or herpesvirus groups, or both, but various representatives of the series had quantitatively and qualitatively different antiviral activities. Several of the compounds, showing the highest antimeasles activity, were investigated extensively. In human cell culture plaque assays, these compounds were active against measles virus at levels of from 15 to 500 mug/ml. At single doses of about 250 to 500 mg/kg, orally in three animal species, significant serum levels of drugs were detected in virus cell culture assays. The mode of action appeared to be therapeutic, as an effect was seen in cell systems infected for at least 24 hr before treatment.

Stability of suspensions of influenza virus dried to different contents of residual moisture by sublimation in vacuo.

After freezing, suspensions of influenza virus were dried by sublimation of water in vacuo to contents of residual moisture of 3.2, 2.1, 1.7, 1, or 0.4%. The stability of the several suspensions was determined by an accelerated storage test. Based on the times predicted for the dried preparations stored at different temperatures to lose 1 log of infectivity titer, the order of stability in relation to residual moistures was as follows: 1.7% > 2.1% > 1% > 3.2% > 0.4%.