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Biomedical subjects

G R Johnson

Publications and source records attributed to G R Johnson.

At least 235 records · Page 13Linked to original sources
PubMed1978

Lymphosarcoma with lymphoblastic leukemia in a New Zealand white rabbit.

An 8 to 10-week-old female New Zealand white rabbit, Oryctolagus cuniculus, which exhibited clinical signs of anorexia, depression, and torticollis was found to have lymphosarcoma with lymphoblastic leukemia. The multiple visceral involvement with neoplastic lymphoid cells observed in this animal was similar to previously reprted cases of lymphosarcoma in the rabbit. An unusual finding was the occurrence of lymphoblastic leukemia since lymphosarcoma in the rabbit has previously been reported as aleukemic.

Animals↗
PubMed1978

Sources and nature of granulocyte-macrophage colony stimulating factor in fetal mice.

At the earliest stages of fetal hepatic hemopoiesis in CBA mice (11-12 days gestation), colony stimulating activity could be found only in peripheral blood, yolk-sac fluid and media conditioned by yolk-sacs (YSCM). The colony stimulating factor (GM-CSF) from YSCM was able to be concentrated by absorption to DEAE-cellulose and subsequent elution. Titration of this material produced a sigmoid dose-response curve in agar cultures of adult CBA bone marrow cells. Unlike the high proportion of granulocyte colonies stimulated by the GM-CSF from mouse lung conditioned medium, all concentrations of YSCM produced a high proportion of macrophage colonies after 7 days of incubation. Mixing experiments eliminated the possibility that a specific inhibitor preventing granulocyte differentiation was present in YSCM. Fetal liver cells were relatively unresponsive to YSCM, but their ability to respond increased with gestational age. When stimulated by YSCM, fetal liver colony forming cells from mice of all gestational ages produced more than 90% macrophage colonies after 7 days of incubation. The experimental data suggest that the proliferation and differentiation of granulocyte and macrophage precursors in the early fetal liver could be controlled by a fetal type of GM-CSF favoring macrophage production.

Animals↗
PubMed1978

Characterization of mouse fetal liver granulocyte-macrophage colony-forming cells using velocity sedimentation.

Fetal liver cells from CBA mice were separated by velocity sedimentation to determine the distribution and properties of granulocyte-macrophage colony-forming cells (GM-CFC). Twelve-day fetal liver GM-CFC separated into two peaks (s=7.7 mm/h, s=9.4 mm/h) in cultures stimulated by mouse lung conditioned medium (GM-CSF MLCM) or human urine (GM-CSFHU). Because fetal liver GM-CFC are of relatively light bouyant density, this finding indicates that fetal liver GM-CFC are much larger than corresponding cell in adult bone marrow (s=4.5 mm/h). By 18 days gestation more slowly sedimenting colony-forming cells were present (s=4.7 mm/h, s=6.0 mm/h). At all gestational ages, the most rapidly sedimenting (larger) colony-forming cells were more responsive to stimulation by GM-CSF MLCM than the smaller (slowly sedimenting) cells. Unlike the situation with adult marrow cells, velocity sedimentation achieved no segregation of GM-CFC according to the morphological type of colony produced.

Animals↗
PubMed1977

Pure and mixed erythroid colony formation in vitro stimulated by spleen conditioned medium with no detectable erythropoietin.

Cells from CBA fetal mouse liver formed pure or mixed erythroid colonies in semisolid agarculture after stimulation by medium conditioned by pokeweed mitogen-stimulated mouse spleen cells. In general shape, the erythroid colonies resembled typical 7-day single or multiple (burst) colonies. However one-third to one-half contained, in addition to erythroid cells, macrophages and neutrophils and, less commonly, megakaryocytes or eosinophils. Culture of micro manipulated single colony-forming cells showed these erythroid colonies to be clones. Colony-forming cells declined in frequency with advancing fetal age, but low numbers were detectable in adult bone marrow. Assays of spleen conditioned medium in polycythemic mice failed to detect erythropoietin; the cloning system may detect a fetal type of erythropoietin-independent, erythropoietic cell since few were detected in adult marrow.

Animals↗
PubMed1977

Surface immunoglobulin characteristics of B-lymphocyte developmental states and B-lymphocyte colony-forming cells.

B-lymphocyte colony-forming cells and various B-lymphocyte developmental states were examined for expression of surface immunoglobulin. B-lymphocyte colony-forming-cells appeared to possess a significantly greater amount of surface immunoglobulin than did newborn 'virgin' B lymphocytes. In terms of surface immunoglobulin content and physical property characteristics (established previously) B-lymphocyte colony-forming cells resembled a more mature B-lymphocyte subset. This subset, as characterized in previous studies, consists of mature virgin B cells that develop from the newborn virgin B cells via a process of nonspecific antigen-induced differentiation. An alternative possibility that B-lymphocyte colony-forming cells are memory B lymphocytes has not been eliminated by this study.

Animals↗
PubMed1977

Ventilation, cardiac frequency and pattern of breathing during exercise in men exposed to O-chlorobenzylidene malononitrile (CS) and ammonia gas in low concentrations.

Ventilation minute volume, tidal volume and cardiac frequency during submaximal exercise have been measured in healthy young soldier volunteers exposed to O-chlorobenzylidene malononitrile (CS) and ammonia gas in concentrations respectively of 0.16 to 4.4 mg.m(-3) and 50 to 344 mg.m(-3). The response of ventilation minute volume to the two gases is apparently similar; both gases cause a reduction of, on average 6%. With low doses this reflects a diminution in respiratory frequency whereas with higher doses it is due to a reduction in tidal volume which is accompanied by tachypnoea. The findings may result from stimulation successively of receptors in the larynx and of irritant receptors in the large airways of the lung. The pain which is a feature of exposure to CS but not to ammonia is due to stimulation of other so far unidentified receptors. Neither gas has a direct effect upon the exercise cardiac frequency.

Adolescent↗
PubMed1977

Naturally occurring neurologic disease in a fallow deer infected with meningeal worms.

Neurologic disease resulting from infection with Parelaphostrongylus tenuis was diagnosed in a fallow deer (Dama dama) from Georgia, with clinical signs and histopathologic lesions similar to those reported for other accidental hosts of P. tenuis. Early fifth stage parasites were found in the spinal meninges and immature parasites were found in the neural parenchyma, but none were recovered from the brain and cranial meninges.

Animals↗
PubMed1977

Worms: transmission from animals to man.

It is useful to know that household pets are not involved in the life cycles of some worms, for example, pinworms. Some worms require a household pet in their cycles: the dog and cat roundworms, heartworms, and the dog and cat hookworms, the larvae of which are responsible for cutaneous larva migrans. Strongyloides (threadworm) infestation is sometimes difficult to diagnose and may be traced directly to the family dog.

Animals↗
PubMed1977

Colony formation by human T lymphocytes in agar medium.

An improved method is described for growing human T-lymphocyte colonies in agar medium containing phytohaemagglutinin (PHA) and sheep red blood cells (SRBC). Cluster and colony growth was obtained when blood mononuclear cells were plated directly in the agar-medium (one-step procedure) or after incubation of cells in liquid medium with PHA (two-step procedure). In the one-step procedure approximately 1 per 100 cells plated formed a cluster containing four to fifty cells. In the two-step procedure 1 per 20 cells plated formed a cluster or a colony (more than fifty cells). The proliferating cells were shown to be sheep-erythrocyte rosette-forming cells (E-RFC). Optimal proliferation was dependent on the presence of phagocytic cells in the cell suspensions cultured. No growth occurred in cultures depleted of E-RFC. Detailed studies of the cycle, velocity sedimentation, and density of the cells plated showed that the majority of cluster- and colony-forming cells were small non-cycline lymphocytes with a sedimentation velocity of 4 mm/hr, and a density between 1-069 and 1-077 g/cm3.

Agar↗
PubMed1977

Acute lung lesions due to zirconium and aluminum compounds in hamsters.

The lung lesions produced by multiple short-term intratracheal instillations of saline solutions of sodium zirconium lactate (NaZL), zirconium-aluminum-glycine hydroxychloride complex (ZAG), and aluminum chlorhydrate (ACH) in hamsters were studied by light and electron microscopy. These solutions produced lesions beginning with exudative pneumonia followed by pneumonitis (interstitial pneumonia) and foreign body granulomas. Electron microscopic microprobe analysis demonstrated the metallic component of the instilled compounds in membrane-bound cytoplasmic inclusions of macrophages. The lesions produced by NaZL and ZAG were similar to those produced by ACH. These lesions were also similar to those in previous reports of aerosol exposure of animals to zirconium or aluminum, or to other unrelated compounds.

Aluminum↗
PubMed1977

Eosinophil colony formation in semisolid cultures of human bone marrow cells.

A method for in situ staining and scoring of eosinophil colonies and clusters in the whole culture dish has been developed for agar cultures of human marrow cells. Cultures stimulated by human placental conditioned medium were found to develop the same proportion of eosinophil, neutrophil, and monocyte colonies as cultures stimulated by conventional peripheral white cell underlayers. Eosinophil colonies and clusters always contained pure populations of eosinophils, and no mixed colonies of eosinophils with other cells were observed. Eosinophil colony formation was delayed in onset relative to neutrophil or monocyte colony formation, but by day 14 eosinophil colonies comprised 20% of all colonies. Eosinophil colonies were absent in cultures of marrow cells from patients with acute myeloid leukemia in relapse, but eosinophil colonies and clusters were found with higher than normal frequency in cultures from acute leukemic patients in remission. A high frequency of eosinophil colonies and clusters was also observed in cultures from three patients with idiopathic thrombocytopenic purpura. The new staining procedure should permit a wide range of studies on eosinophil precursor populations in the marrows of patients with various diseases.

Bone Marrow Cells↗
PubMed1977

Electron microscopy of rapid identification of animal viruses in hematoxylin-eosin sections.

Routine hematoxylin-eosin stained, paraffin sections were processed for electron microscopy, using a rapid method for localization of animal viruses. Formalin fixation was effective in preserving DNA as well as RNA viruses, however cellular fine structural details and organelles were not well preserved. The procedure is useful for morphological recognition of viral groups and as a rapid diagnostic aid for identifying viral disease.

Animals↗
PubMed1977

Radiation-induced enlargement of granulocytic and macrophage progenitor cells in mouse bone marrow.

The peak sedimentation velocity of C57BL mouse bone marrow progenitors of granulocytes and macrophages (GM-colony-forming cells, GM-CFC's) increased from 4.3 mm/h to 7-8 mm/h by 2 days after 250 rad whole body irradiation and slowly returned to normal over the next 3 weeks. Ppreliminary irradiation and/or endotoxin injection did not prevent this radiation-induced change. Some change in sedimentation velocity was seen with as little as 100 rad irradiation. Neither buoyant density nor cell cycle changes could account for the sedimentation velocity data which therefore indicate a major volume increase in the GM-CFC's. This size enlargement affected all subpopulations of GM-CFC's which consequently maintained their size relationship with one another.

Animals↗
PubMed1977

Heterogeneity in human neutrophil, macrophage and eosinophil progenitor cells demonstrated by velocity sedimentation separation.

Progenitor cells of neutrophils, monocyte-macrophages, and eosinophils in human marrow were enumerated in agar cultures stimulated by placental conditioned medium or white cell underlayers. Fractionation of marrow populations by velocity sedimentation showed that the profiles of neutrophil and macrophage colony-forming cells shifted from a peak of 8-9 mm/hr in 7-day cultures to a peak of 6-7 mm/hr in 14-day cultures. This shift was due to degeneration of some early colonies formed by rapidly sedimenting cells and the delayed formation of colonies by slowly sedimenting cells. Eosinophil colony formation was delayed until the second week of incubation. Further evidence of heterogeneity was the observation that rapidly sedimenting colony forming cells were more responsive to stimulation than more slowly sedimenting cells. In the macrophage and eosinophil populations, cluster-forming cells were partially segregatable form colony-forming cells. The observed heterogeneity was similar to the described previously in the mouse and suggests that separate subpopulations of progenitor cells may exist within each hemopoietic family that could possibly give rise to functionally different progeny.

Cell Separation↗
PubMed1976

The heroin epidemic in San Francisco: estimates of incidence and prevalence.

Much attention has recently been focused on the question of the extent of heroin use in America. In a worthwhile effort to call public attention to the problem, many estimates of its size have evidenced a tendency toward exaggeration and aggrandizement. This paper presents methods of estimation of the extent of heroin addiction which, when carefully employed, should effectively correct such distorted estimates. Two general types of estimation are employed, incidence and prevalence. Incidence estimates are concerned with new cases of heroin addiction that occur in a specific population within a given amount of time. These estimates are based upon self-report data from addicts regarding date of first addiction. When corrected for the "lag phase" (that period of time between onset of first addiction and eventual visit to a treatment program), these data permit accurate retrospective charting of incidence trends. Prevalence estimates focus on all known cases of heroin addiction in a specific population within a given amount of time. Three separate types of prevalence estimates from three separate sources are outlined in this article: estimates based on overdose death data, estimates based on crime statistics, and estimates of "unknown" addicts. In outlining these methods, this article describes the fluctuations in heroin addiction in one major American city, San Francisco, California. After analyzing data gathered from a sample of 2,367 addicts contacted over a 3-year period, this study suggests that the incidence of heroin addiction seems to have declined after 1970. Possible factors underlying this apparent decline in heroin addiction are then discussed, including the post-1970 maturation of the "population at risk," the effectiveness of antidrug media messages, the changing drug fashions in the heroin subculture, and the gradual deterioration of the quality and potency of street heroin.

Attitude↗