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Biomedical subjects

J G HIRSCH

Publications and source records attributed to J G HIRSCH.

At least 19 recordsLinked to original sources
PubMed1964

ELECTRON MICROSCOPE STUDIES ON THE DEGRANULATION OF RABBIT PERITONEAL LEUKOCYTES DURING PHAGOCYTOSIS.

Electron microscopic observations have established the mechanisms underlying degranulation of neutrophils and eosinophils during phagocytosis. The content of the granules is released into the phagocytic vacuole when their membranes fuse with the membrane lining the vacuole. The discharge mechanism appears to be applicable to the various morphological types of granules seen in rabbit polymorphs. It has been proposed that the release of material to the outside of the cell or the discharge of material into intracellular vacuoles, events involving membrane fusion, be termed "exoplasmosis."

Animals↗
PubMed1964

ANTISERUM TO LEUCOCYTE LYSOSOMES. ITS CYTOTOXIC, GRANULOLYTIC, AND HEMOLYTIC ACTIVITIES.

Antisera to rabbit polymorph granules and to rabbit erythrocytes have been prepared in guinea pigs. Both antigranule and antierythrocyte sera are hemolytic and both exhibit striking cytotoxicity on leucocytes. The sequence of toxic events, as observed by phase contrast cinemicrophotography and electron microscopy, consists of explosive granule lysis, cell swelling, cytoplasmic liquifaction, and nuclear fusion. Other rabbit cells are also susceptible to these cytotoxic effects, but cells, including polymorphs, of other mammals are not. Cytotoxic action of the antisera requires, in addition to the antibody, heat-labile serum factors and divalent cations, suggesting that the action is a combined one of antibody and complement. The morphologic observations have been supported by biochemical studies demonstrating release into the medium of granule-bound hydrolases following exposure of polymorphs or of isolated granules to the antigranule or antierythrocyte sera. Granulolytic activity of the antisera can be reduced or removed by absorption with either rabbit leucocyte granules or with erythrocytes, indicating that leucocyte granules and erythrocytes have an identical or similar membrane constituent. The observations lend support to the notion that lysosomal hydrolases may exert autolytic effects in some situations.

Animals↗
PubMed1963

MOTION PICTURE STUDY OF THE TOXIC ACTION OF STREPTOLYSINS ON LEUCOCYTES.

The initial morphologic alteration in rabbit polymorphonuclear leucocytes exposed to streptolysin is rapid and extensive lysis of cytoplasmic granules. The granules appear to rupture directly into the cell sap. Within a few minutes following degranulation, the leucocyte rounds up, filamentous processes appear on the cell membrane, the cytoplasm liquefies, and finally the nuclear lobes swell and fuse. Streptolysin O causes these changes in intact leucocytes when added in concentrations only slightly higher than those required for release of hydrolases from isolated liver lysosomes, and furthermore exerts its action on granulocytes promptly. On the other hand streptolysin S acts on white cells only after a 15 to 30 minute delay, and the levels necessary to disrupt granules in leucocytes are considerably higher than those which act on lysosome suspensions. Exposure of rabbit alveolar macrophages to streptolysin O also results in lysis of granules, soon followed by alterations in the cytoplasm and membrane. The observations are in accord with the hypothesis that streptolysins penetrate the leucocyte membrane and bring about lysis of granules. Autolytic enzymes released from the granules might then be responsible for the subsequent damage seen in various other cell structures.

Animals↗
PubMed1963

ISOLATION OF GRANULES FROM EOSINOPHIL LEUCOCYTES AND STUDY OF THEIR ENZYME CONTENT.

Eosinophils were separated from other types of cells in horse blood or rat peritoneal fluid by centrifugation in concentrated albumin solutions. Eosinophils did not appear to be damaged by this separation procedure. A technique was also devised for isolation of cytoplasmic granules from eosinophils, thus allowing studies on enzyme content of the granules. Granules from both horse and rat eosinophils contained a number of hydrolytic enzymes, similar in variety and in concentration to those previously found in granules of rabbit polymorphonuclear leucocytes. Eosinophil granules differed from those of the rabbit granulocyte in their high content of peroxidase and the absence of lysozyme and phagocytin. On disruption of eosinophil granules by repeated freezing and thawing in saline, cathepsin, ribonuclease, arylsulfatase and beta glucuronidase were released into solution, but phosphatases were partially and peroxidase completely bound to the insoluble granule residue. Peroxidase could be extracted from the granule residue with weak acid. Eosinophil granules thus are lysosome-like structures.

Animals↗
PubMed1963

MOTION PICTURE STUDIES ON DEGRANULATION OF HORSE EOSINOPHILS DURING PHAGOCYTOSIS.

Horse eosinophil function has been studied in vitro by means of phase contrast cinemicrophotography. Locomotion of horse eosinophils was inhibited by serum factors reacting with glass surfaces. Under appropriate conditions which eliminated this inhibitory effect, eosinophils moved about and ingested some particles as rapidly as did neutrophils. Eosinophils were attracted to and readily engulfed such diverse materials as yeast cell walls, foreign erythrocytes, and antigen-antibody precipitates. Specific antibody was required for phagocytosis of red cells, and greatly accelerated the uptake of yeast cell walls. Horse eosinophil granules situated adjacent to material being engulfed disrupted with discharge of granule contents into or alongside the phagocytic vacuole. Granule disruption resulted in a clear zone and deposition of amorphous, phase-dense material. A heat-labile serum factor was required for degranulation of eosinophils ingesting foreign red cells, but not for degranulation during engulfment of yeast cell walls or antigen-antibody precipitates. Horse eosinophils were incapable under these conditions of engulfing an entire human red cell. The eosinophil commonly put out a large pseudopod to surround about half the red cell, and then appeared to constrict this pseudopod distally to cut the erythrocyte in half. It is concluded that eosinophils are phagocytic cells, resembling neutrophils in many of their properties. Any specific functions of eosinophils, distinguishing them from other phagocytes, remain to be discovered.

Animals↗
PubMed1962

Cinemicrophotographic observations on granule lysis in polymorphonuclear leucocytes during phagocytosis.

Phagocytosis of yeast cell walls and of Bacillus megaterium by human, rabbit, and chicken polymorphonuclear leucocytes has been observed by phase contrast microscopy and recorded on motion picture film. In suitably thin preparations intracellular events could be visualized well. Lysis of cytoplasmic granules began early in the course of the ingestion process, rupture occurring only in granules adjacent to the microorganism being engulfed. Formation of a visible vacuole about the ingested particle frequently followed degranulation. Chicken polymorphonuclear leucocytes, with their large phase-dense granules, were particularly suitable subjects for observations on detailed morphologic aspects of granule lysis. Rupture took place rapidly (0.1 second or less); in place of the granule there appeared a clear zone, often with a small phase-dense round structure in its center. Also accompanying granule lysis was an increase in phase density of the adjacent surface of the microorganism. Over the course of the following few seconds the darkening on the organism faded, the dense small body disappeared from view, and the clear zone contracted towards the engulfed particle. The observations are discussed in relation to the hypothesis that fusion takes place between the granule membrane and the invaginated cell membrane overlying the ingested particle, with discharge of granule contents directly into the phagocytic vacuole.

Animals↗
PubMed1960

Degranulation of polymorphonuclear leucocytes following phagocytosis of microorganisms.

A marked reduction in numbers of cytoplasmic granules in rabbit and human polymorphonuclear leucocytes takes place following ingestion of various microorganisms or of a yeast cell wall preparation. The degranulation occurs within 30 minutes of phagocytosis, and is directly related to the quantity of material engulfed. White cells completely degranulated following phagocytosis of large numbers of microorganisms remain viable for at least 1 hour. The granules of polymorphonuclear leucocytes contain the antimicrobial agent, phagocytin, and various digestive enzymes. These substances thus are released into the cytoplasm or into vacuoles following ingestion of foreign material. The granule system and granule lysis mechanism may well play a central role in the primary function of these specialized cells; namely, that of destroying invading microorganisms.

Animals↗
PubMed1960

The influence of phagocytosis on the intracellular distribution of granule-associated components of polymorphonuclear leucocytes.

Control and phagocyting populations of rabbit polymorphonuclear leucocytes have been compared in terms of the content and distribution of phagocytin and selected hydrolytic enzymes. Following incubation at 37 degrees C., the cells were disrupted by homogenization and separated into an 8,200 g pellet and supernatant fluid. The high speed pellet from control leucocytes contained all the larger particulate elements of the cell including intact cytoplasmic granules. The ingestion of large numbers of heat-killed bacteria was accompanied by a fourfold reduction in the total phagocytin content of the leucocyte, whereas phagocytosis did not influence the recovery of histone-like bactericidin from nuclei. Engulfment of microorganisms led to a progressive decrease in the activity of phosphatases, beta glucuronidase, and cathepsin extractable from the 8,200 g pellet, with a concomitant increased activity of these enzymes in the supernatant fraction. No significant difference in the total enzyme content of control and phagocyting cells was noted. These findings are consistent with the lysis of granules following phagocytosis and the liberation of granule constituents into the cytoplasm of the leucocyte.

Cathepsins↗
PubMed1960

The isolation and properties of the specific cytoplasmic granules of rabbit polymorphonuclear leucocytes.

A method has been described for isolation of the specific cytoplasmic granules of rabbit polymorphonuclear leucocytes. Homogeneous suspensions of leucocytes were disrupted by lysis in 0.34 M sucrose. This procedure liberated the cytoplasmic contents of the cell and dissolved a considerable proportion of the nuclei. Following disruption, the sucrose lysate was separated into three fractions by differential centrifugation, i.e. 400 g or nuclear pellet, 8,200 g or granule pellet and the postgranule supernate. Microscopic examination revealed that the 8,200 g pellet was composed of intact granules as well as occasional mitochondria. The other two fractions were morphologically heterogeneous. Studies with isolated granules demonstrated their lysis by a variety of weak acids and surface-active agents. When buffered solutions were employed between the ranges of pH 2.0 and 9.0, granule lysis began at pH 5.5 and was complete at pH 4.0. Chemical analysis disclosed that the granule pellet contained protein and phospholipid with only traces of nucleic acids. Approximately 70 to 80 per cent of the total cellular antimicrobial agent phagocytin was present in the granule fraction. This material was liberated from the granules by acid (pH 5.0 or lower). Studies on selected enzymes showed that acid phosphatase, alkaline phosphatase, nucleotidase, ribonuclease, deoxyribonuclease, and beta glucuronidase were predominantly localized in the granule fraction. Approximately 50 per cent of total cellular lysozyme and cathepsin were also present in the 8,200 g pellet. Disruption of the granules was associated with the release of the majority of granule protein and enzymes in a non-sedimentable form. The properties and composition of rabbit polymorphonuclear leucocyte granules seem to be analogous to those of liver lysosomes.

Acid Phosphatase↗
PubMed1960

Comparative bactericidal activities of blood serum and plasma serum.

Rabbit and human plasma can be prepared without resort to anticoagulants by employing low temperatures and non-wetting surfaces. Serum formed after clotting of rabbit plasma devoid of cells and platelets manifests essentially no bactericidal activity on Bacillus subtilis, Bacillus megaterium, and a strain of Staphylococcus aureus. In contrast, rabbit blood serum exhibits this activity to a high degree. Rabbit plasma rich in platelets gives rise to a serum with capacity to kill these Gram-positive microbes equal to that of serum prepared from whole blood. This heat-stable antibacterial agent is efficiently formed or released when platelets are present during the coagulation of plasma, but not on incubation of platelets in heparinized or citrated plasma or in saline. Leucocytes and red cells appear to play no significant role in its production. Rabbit blood serum and plasma serum have similar heat-labile lethal effects on enteric bacilli. Human serum, whether from blood or plasma, manifests much less bactericidal activity on Bacillus subtilis than does rabbit blood serum. These findings serve to emphasize the fact that substances formed or released during coagulation of whole blood may impart to the serum activities not present in circulating plasma.

Animals↗
PubMed1960

Studies of phagocytosis of group A streptococci by polymorphonuclear leucocytes in vitro.

Studies have been made on phagocytosis and killing of Group A streptococci during mixing with suspensions of leucocytes in vitro. Under appropriate test conditions an anti-phagocytic effect can be demonstrated for the streptococcal hyaluronic acid capsule as well as for its M protein. The results obtained suggest an explanation for the suitability of human, but not rabbit, blood for opsonophagocytic tests designed to measure type-specific streptococcal antibodies. Human sera contain a factor which counteracts the anti-phagocytic effects of streptococcal hyaluronic acid capsules, and hence human blood serves well for detection of antibodies which combine with the only other phagocytosis-resisting component of this microorganism, namely M protein. In contrast, rabbit sera contain none of this factor, and addition of antibody to M protein to phagocytic test systems employing rabbit serum does not necessarily render the streptococci susceptible to engulfment by white cells, since the hyaluronic acid capsule may continue to interfere with phagocytosis. The nature of the human serum factor which opsonizes encapsulated streptococci is unknown. It does not appear to be an antibody or an enzyme capable of depolymerizing hyaluronic acid.

Antibodies↗