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Biomedical subjects

S C Johnson

Publications and source records attributed to S C Johnson.

At least 127 records · Page 7Linked to original sources
PubMed1987

Fractionation of the Providencia stuartii cell envelope.

Cell envelopes (i.e. unfractionated inner and outer membranes) were obtained from Providencia stuartii by following procedures previously applied to the isolation of envelopes from Escherichia coli. The P. stuartii envelopes contained known inner membrane enzymes that included a variety of dehydrogenases and ATPase. The catalytic activity of the ATPase depended upon the concentration of magnesium ions, the substrate (ATP) level and the ratio of magnesium ions to ATP. Cell envelopes from P. stuartii were further fractionated to recover inner and outer membrane polypeptides by treatment with the detergent Sarkosyl. Proteins from the periplasmic region were recovered by a simple osmotic shock procedure also previously applied to E. coli. The purity of the various P. stuartii cell envelope fractions was assessed by a combination of techniques that included one- and two-dimensional gel electrophoresis of proteins, enzyme assays and detection of penicillin-binding proteins.

Bacterial Outer Membrane Proteins↗
PubMed1986

Creating a healthy climate for health care.

Hospitals must reinvent health care while remaining close to communities and their needs. The MHA's role in that process will be to promote the healthy climate that health care needs.

Community-Institutional Relations↗
PubMed1985

Continuous expression of I-A antigen by peritoneal macrophages from mice resistant to Mycobacterium bovis (strain BCG).

Monoclonal antibodies were used to monitor the expression of I-A antigen on the surface of macrophages obtained from mice immunized to Mycobacterium bovis (strain BCG). Unlike the transient nature of I-A expression by macrophages from Listeria-injected mice, peritoneal macrophages from mice injected 28 days previously with 10(4) BCG expressed I-A continuously. The continued expression was not due to the presence of antigen or of contaminating lymphocytes. When we compared the kinetics of I-A expression from different strains of mice, the continuous expression of I-A correlated with the genetic resistance of the mice to BCG. Macrophages from mice that were resistant to BCG expressed I-A continuously, while macrophages from BCG susceptible mice expressed I-A transiently. Injection of resistant mice with Salmonella typhimurium did not result in the induction of a population of macrophages that expressed I-A continuously. This suggests that the Bcg gene may not be the same as that responsible for resistance to Salmonella (Ity) or Leishmania (Lsh).

Animals↗
PubMed1983

Histopathological study of the attrition of challenge cercariae of Schistosoma mansoni in the skin of mice immunized by chronic infection and by use of highly X-irradiated cercariae.

To find direct evidence for the sites of death of newly transformed schistosomula of Schistosoma mansoni in the skin of challenged immunized hosts, a histopathological study of the skin of chronically infected mice and of highly X-irradiated cercaria-immunized mice was made at different post-challenge times. Attrition of infecting organisms in naive mice was used as a control. In general, three main kinds of schistosomular attrition were observed: (1) in the granulocytic exudates in the epidermis, (2) in the granulocytic aggregates in the subcutaneous tissue, and (3) in the granuloma-like foci in the subcutaneous tissue. Schistosomula killed by the epidermal granulocytic exudates and by the subcutaneous granuloma-like foci occurred in all three groups of mice, but the schistosomula killed by the subcutaneous granulocytic aggregates were found only in the highly X-irradiated cercaria-immunized animals. Schistosomula killed by the epidermal granulocytic exudates were encountered occasionally in the challenged naive mice but more frequently in both the challenged chronically infected mice and the challenged highly X-irradiated cercaria-immunized mice. The number of subcutaneous granuloma-like foci was greater in the challenged mice immunized with highly X-irradiated cercariae than in the challenged naive mice or the challenged chronically infected mice. Another differentiating character among the three groups of mice was that in the highly X-irradiated cercaria-immunized group, the subcutaneous granuloma-like foci appeared on day 3 after the challenge, but on day 5 in the naive and chronically infected groups. The results clearly indicate that skin is an important site for the attrition of the challenged cercariae in the highly X-irradiated cercaria-immunized mice, and that immunity in the chronically infected and X-irradiated cercaria-immunized mice occurs by different mechanisms.

Animals↗
PubMed1983

Vaccination against bovine schistosomiasis japonica with highly X-irradiated schistosomula.

Cercariae of the Chinese mainland strain of Schistosoma japonicum were used. Eighteen cattle, divided into six groups of three each, were immunized with schistosomula transformed from cercariae exposed to three different doses of X-irradiation (24, 36, and 48 kR). The immunization was given either once, twice, or thrice, and the number of immunizing schistosomula was 10,000 or more in each immunization. The immunized cattle were challenged with 500 normal cercariae. Five native cattle were similarly infected with normal cercariae as controls. All cattle were killed 32-33 days after challenge or infection, and the worms were obtained by perfusion. The mean worm reduction in the 18 experimental animals varied from 42.1 to 96.0%. The mean percent worm reduction of the six experimental groups varied from 54.8 to 87.1. The reduction was greater with increasing numbers of immunizations, and was higher in the groups immunized with schistosomula exposed to 36 kR than in those exposed to 24 or 48 kR. Statistical analyses showed that all immunized groups yielded significantly fewer worms than controls. However, the three doses of X-irradiation (24, 36, and 48 kR) had no significant effect for a fixed number of immunizations (1, 2, or 3). The means for both two and three immunizations were significantly different from the mean for one immunization, although they were not significantly different from each other.

Animals↗
PubMed1982

Schistosoma mansoni: is acquired immunity induced by highly x-irradiated cercariae dependent on the size of the challenging dose?

A high degree of immunity, as shown by a 91% reduction of the number of worms recovered was found in five groups of mice that were immunized five times with highly X-irradiated cercariae and then challenged with 10, 20, 50, 100, or 500 normal Schistosoma mansoni cercariae. The results indicated that there were no significant differences in worm reduction in immunized mice challenged with different numbers of cercariae; consequently the immunity induced by this immunization method did not appear to be challenge-dose-dependent. However, the results also showed that when immunized mice were challenged with 500, 100, 50, 20, and 10 cercariae, 0, 13, 26, 56, and 68%, respectively, of the experimental animals were free of worms. Thus, the percentage of worm-negative cases increased as the number of challenge cercariae decreased. When viewed in this manner, the acquired immunity may be considered challenge-dose-dependent as well. If this method of vaccination is used for schistosomiasis control, we may anticipate that in both hypo- and hyperendemic areas, the intensity of infection and the severity of the disease will be reduced owing to a reduction in worms burdens, and in hypoendemic areas, there will be a number of worm-free cases.

Animals↗
PubMed1980

Bullous amyloidosis. Case report with ultrastructural studies.

A 51-year-old man with primary systemic amyloidosis initially manifested periorbital purpura; later, skin fragility and hemorrhagic bullae developed. The bullae healed with formation of milia. The bullae were shown by electron microscopy to result from breaks in the fragile dermal amyloid deposits well below the basal lamina.

Amyloidosis↗
PubMed1979

Actinic reticuloid. A clinical, pathologic, and action spectrum study.

A 54-year-old man suffered from a chronic dermatitis that was more severe on light-exposed areas. Skin biopsy specimens revealed histopathologic findings consistent with those seen in mycosis fungoides. Ultrastructural studies demonstrated the existence of lymphoid cells with hyperconvoluted nuclei, typical of the mycosis fungoides cell or Sézary cell, within the epidermis, dermis, and peripheral blood. Light testing with a monochromator showed abnormal photosensitivity to both short- and long-wave ultraviolet light as well as to the violet, blue, and green wavelengths of visible light. The features of this patient's disease indicate actinic reticuloid.

Biopsy↗
PubMed1977

Landry-Guillain-Barré-Strohl syndrome. A study of 302 cases.

Three hundred and two cases of Landry-Guillain-Barré-Strohl syndrome (LGBSS) are studied and relevant literature is reviewed. The existing diagnostic criteria appear not in keeping with the histopathological and immunological findings of this condition, hence some modifications have been suggested. The role of steroids in the treatment of this disorder is critically examined, and no benefit is found to be gained from their use.

Adolescent↗