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Biomedical subjects

J S Johnson

Publications and source records attributed to J S Johnson.

At least 91 records · Page 5Linked to original sources
PubMed1978

A new approach to cephalometric analysis of the dental base relationship.

1. The Reference line, connecting the centres of area of the projected skull outline, the cranium and the face, is relatively easy to locate and forms a more stable base from which to measure changes in the face in profile including the dental base relationship, than are the sella-nasion, maxillary or mandibular planes. 2. The Reference-Profile angle is a reliable assessor of a bimaxillary prognathism or retrognathism. Its mean value is 44 degrees. Angles above this value are associated with a bimaxillary retrognathism, and angles below this value with a bimaxillary prognathism. 3. The Reference-Dental Base angle is the most consistent for assessing the anterior jaw relationship between the maxilla and mandible. Its mean value of 50 degrees indicates a Class I relationship. Angles of 53 degrees and above indicate clinical Class II cases and angles of 48 degrees and below indicate clinical Class III cases. 4. These two angles are potentially valuable diagnostic indices for use in orthodontic clinical assessment.

Adolescent↗
PubMed1978

Normal mouse serum immunosuppressive activity: action on adherent cells.

The immunosuppressive activity of normal mouse serum (NMS) was evaluated by enumeration of primary in vitro plaque-forming cell response produced by normal spleen cell suspensions in response to sheep erythrocytes. The site of action of the inhibitor(s) was shown to be at the level of adherent cells since incubation of this cell type with NMS could reproducibly inhibit responses, whereas, in appropriate experiments, incubation of nonadherent cells with NMS had no effect. Furthermore, addition to normal spleen cells of excess spleen-adherent cells, normal peritoneal adherent cells, or of 2-mercaptoethanol could abrogate the inhibitory ability of NMS. Addition of excess nonadherent cells under the same conditions had no influence on inhibition. NMS was also shown to decrease the number of cell clusters, hemolytic clusters, and the number of nucleated cells recovered upon culture termination. It is suggested that NMS, acting on the adherent cell may hinder cell-to-cell contact and interactions.

Animals↗
PubMed1977

Genetic deficiency of the fourth component of complement (C4) in Wistar rats.

A chance observation has led to the discovery of single component complement deficiency in Wistar rats. During serial total haemolytic activity (CH50) determinations on 10 male rats, 2 were consistently found to have values 20% or less than that of the others. An additional 30 males (200--220 g) and 20 females (180--200 g) were screened for CH50 and the defect was found in 10 of the males but none of the females. Mixtures of sera of high and low haemolytic activity gave intermediate values between the two populations arguing against the presence of an inhibitor of the complement system. Single component analysis revealed the defect to reside in the fourth component of complement (C4). Highly purified human C4 completely reconstituted the haemolytic activity of the complement deficient rat serum. A linear relationship between C4 and CH50 titres was observed. Data from preliminary selective breeding experiments point toward an autosomal recessive mode of inheritance. Animals with intermediate values were observed indicating a gene dosage effect with which the heterozygote may be recognized.

Animals↗
PubMed1976

Rheumatoid factor-producing cells detected by direct hemolytic plaque assay.

Lymphocytes secreting anti-IgC antibodies, rheumatoid factors (RF), can be detected in the peripheral bloods, synovial fluids, and bone marrows of patients with seropositive rheumatoid arthritis by using a direct plaque-forming cell (PFC) assay with sheep erythrocytes sensitized with reduced and alkylated rabbit IgG hemolysin. The autospecific nature of the RF produced by RF-PFC was indicated by inhibition studies in which the order of patency was human IgG greater than rabbit IgG greater than bovine IgG. In metabolic studies puromycin, cycloheximide, and venblastine suppressed RF-PFC. Cyclic AMP and cyclic GMP were without effect. A need was recognized for using full tissue culture media during the cell separation and plaquing procedures to optimize detection of the RF-PFC. RF-PFC may appear in the blood of patients intermittently despite their continuing presence in the bone marrow. They have been found in the peripheral blood, especially during acutely exacerbating polyarticular synovitis, generalized vasculities, or generally active, aggressive disease. RF-PFC were found in synovial effusions of new or recrduescent acute synovitis. RF-PFC were observed to disappear from the peripheral circulation and the bone marrow during therapy with cytotoxic drugs. The data are consistent with the hypothesis that the appearance of RF-PFC in the peripheral blood represents an anamnestic response to transiently appearing antigen. The nature of the antigen is not specified. The bone marrow may be a site of origin of RF-PFC.

Antibody Specificity↗
PubMed1976

A comparison of age estimation using discriminant function analysis with some other age estimations of unknown skulls.

Available methods of estimating the ages of unknown skulls are notoriously inaccurate. Making use of a unique opportunity to view several hundreds of remains from two nineteenth century cemeteries, various methods of estimating age were tested. A statistical method which gives relative weighting to each age indicator before reducing the data to a single pooled age estimate was found to be the most reliable. The greater the number of criteria which were utilized for age estimation, the more highly correlated was the estimated age of remains with the actual age at death. The degree of accuracy in estimating the ages of skulls of under 20 years was relatively high, when only the stage of development of dental tissues was examined. With increasing age over 20 the accuracy decreased, particularly at ages over 45. The range of age distribution of skulls estimated from published data on suture closure tended to be more restricted than that which may acutally occur.

Adult↗
PubMed1976

Effect of vagotomy on anaphylaxis in the rat.

Vagatomy or atropinization protects rats from lethal anaphylaxis and histamine shock. These procedures do not significantly affect production of anaphylactic antibodies or release of histamine following induction of anaphylaxis. The response of the intestinal microvasculature during anaphylaxis is observed to consist of an early brief increase permeability followed by prolonged and irreversible damage. Cholinergic blockade abolishes the latter and markedly reduces deposition of colloidal carbon and immune complexes in the vessel. The possible relevance of these observations to development of chronic immunological vascular disease is discussed.

Anaphylaxis↗
PubMed1975

Complement fixation by rheumatoid factor.

The capacity for fixation and activation of hemolytic complement by polyclonal IgM rheumatoid factors (RF) isolated from sera of patients with rheumatoid arthritis and monoclonal IgM-RF isolated from the cryoprecipitates of patients with IgM-IgG mixed cryoglobulinemia was examined. RF mixed with aggregated, reduced, and alkylated human IgG (Agg-R/A-IgG) in the fluid phase failed to significantly reduce the level of total hemolytic complement, CH50, or of individual complement components, C1, C2, C3, and C5. However, sheep erythrocytes (SRC) coated with Agg-R/A-IgG or with reduced and alkylated rabbit IgG anti-SRC antibody were hemolyzed by complement in the presence of polyclonal IgM-RF. Human and guinea pig complement worked equally well. The degree of hemolysis was in direct proportion to the hemagglutination titer of the RF against the same coated cells. Monoclonal IgM-RF, normal human IgM, and purified Waldenström macroglobulins without antiglobulin activity were all inert. Hemolysis of coated SRC by RF and complement was inhibited by prior treatment of the complement source with chelating agents, hydrazine, cobra venom factor, specific antisera to C1q, CR, C5, C6, or C8, or by heating at 56 degrees C for 30 min. Purified radiolabeled C4, C3, and C8 included in the complement source were bound to hemolysed SRC in direct proportion to the degree of hemolysis. These data indicate that polyclonal IgM-RF fix and activate complement via the classic pathway. The system described for assessing complement fixation by isolated RF is readily adaptable to use with whole human serum.

Animals↗
PubMed1975

Transmission electron microscopy of tissue prepared for scanning electron microscopy by ethanol-cryofracturing.

Tissue processed for scanning electron microscopy by ethanol-cryofracturing combined with critical point drying was embedded and sectioned for transmission electron microscopy. Study of specimens cut in a plane passing through the fracture edge indicated that preservation of cellular fine structure of fractured cells was excellent. Even at the most peripheral edge of the fracture there was no evidence that movement of cytoplasmic components occurred to distort the original structural organization of fractured cells. Lack of cytoplasmic detail in ethanol-cryofractographs has been due more to the nature of the fracturing of the tissue and to the obscuring effects of the metal coating than to structural deformation at the fracture edge or to limitations in resolving power of the scanning electron microscope used.

Animals↗
PubMed1974

Some social and forensic aspects of exhumation and reinterment of industrial revolution remains.

The aetiological aspects of exhumed remains from two burial sites were examined using 1839 and 1879 as years of comparison. We tried to discover whether the sample of recovered remains was representative of those buried. The state of the remains varied according to the type of soil and coffin material in which they were buried. At the earlier date most deaths were caused by infectious lesions rather than degenerative ones and 76% of those who died were below employable age-whereas in 1879 the commonest causes of death were tuberculosis ("phthisis") and bronchitis, and 42% died before they could be employed. The registration of deaths were recorded more accurately at the later date, and it was easier to build up a picture of the age, sex, and occupation of the people who died.

Age Factors↗