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Biomedical subjects

R H Rigdon

Publications and source records attributed to R H Rigdon.

At least 19 recordsLinked to original sources
PubMed1982

Experimental leprosy with Mycobacterium lepraemurium in hairless mice (Mus musculus).

Forty-three homozygous albino hairless mice (Mus musculus) were inoculated intradermally on the head, back, sides and base of the tail with suspensions of lepromatous tissue containing numerous Mycobacterium lepraemurium (Hawaiian strain). Visible nodules were noted in all mice. These lepromatous nodules enlarged slowly and often merged with each other, covering up to two thirds of the dorsum. Several mice became blind during the course of the infection. All of the mice died or were killed 68 to 287 days following inoculation. Post-mortem examinations on representative mice showed, in addition to observed cutaneous lesions, generalized systemic murine leprosy. Smears and histological sections from nodules, skin, lymph nodes, spleen, liver, kidney, heart and lung were positive for acid-fast bacilli. The cysts in the skin (which are degenerated hair follicles filled with keratin-like material and which are one of the characteristics of hairless mice) contained scattered acid-fast bacilli, but no acid-fast globi. Ten mice with hair (M. musculus) which were used as controls did not reveal noticeable cutaneous nodules; however, all developed generalized visceral leprosy similar to that of the hairless M. musculus. Thus, hairless mice (with thymus) can be looked upon as a model for studying experimental cutaneous leprosy.

Animals↗
PubMed1982

Murine xenotropic type C viruses. IV. Replication and pathogenesis of ducks.

The xenotropic (X-tropic) mouse type C virus (MuLV) and its pseudotype of murine sarcoma virus (MSV) were inoculated into several fertilized developing Pekin duck eggs. The development of the duck embryos was substantially reduced in those receiving the X-tropic viruses compared to eggs inoculated only with tissue culture medium. Infections virus was isolated from some of the adult animals; in others, evidence for integrated virus sequences in the tissues was noted. No specific pathology was found in the ducks that received X-trophic MuLV alone, but one duck developed multiple fibrosarcomas when inoculated at birth with the X-tropic virus pseudotype of MSV. Two ducks receiving X-tropic MuLv had signs of haematopoietic disorders. In addition, more virus-inoculated animals had evidence of hepatitis and encephalitis than control ducks. Antibody production to X-tropic MuLv was present in several ducks inoculated with virus either in embryo or at birth. Absence of antiviral antibodies was noted in those animals whose tissue contained replicating virus. These studies confirm the observations with X-tropic virus in tissue culture. They demonstrate in vivo that avian species are susceptible to infection by the mouse X-tropic virus and that their fibroblasts can be transformed by the X-tropic MuLV pseudotype of MSV.

Animals↗
PubMed1981

Problems in a statistical study of disease based on death certificates.

Data obtained from death certificates are used to establish the frequency of diseases for vital statistics. In Morgan County, Georgia, 5,787 death certificates registered between 1927 and 1979 were examined for this study. Data referable to age, sex, race, and the cause of death were recorded, with primary emphasis on cancer. The cause of death in these certificates was based primarily on clinical diagnoses. Some certificates cited neoplasms in which the site of origin was not given, and in others the type of neoplasm was difficult to correctly code. In some, a tumor was recorded but was not coded. The format of these certificates was changed by the state several times during this period, apparently to improve their credibility. Review of these registered death certificates, used for vital statistics in both Georgia and Washington, indicates that the data would contribute no scientific information on the frequency of cancer.

Adolescent↗
PubMed1975

Reaction associated with a silicone rubber gel: an experimental study.

A blend of Silastic 382 (Room Temperature Vulcanizing, RTV) Medical Grade silicone oil and a catalyst was prepared in vitro, in both the catalyzed and noncatalyzed state, and injected subcutaneously in mice, rats, and rabbits. When properly blended, this catalyzed material, referred to as "silicone gel," formed a soft rubbery mass that remained at the site of injection. Properly catalyzed silicone rubber gel produces no macroscopic inflammatory reaction, attracts few polymorphonuclear leucocytes, and after 5-6 days a thin fibrous capsule begins to form aroung the gel. No degeneration of the silicone gel was observed during the 62 days of this experiment. Additional rats with this silicone gel have been under observation for 8 months and clinically have shown no changes in the local mass of silicone. If the catalyst is partly oxidized when added to the silicone fluid, the degree of gelling is much less. A local mass usually forms at the site of injection with some of the fluid diffusing into the tissue, forming minute cysts. The inflammatory reaciton is characterized by polymorphonuclear leucocytes, associated with many macrophages and giant cells phagocytizing oil droplets and particles of the diatomaceous earth. The pathogenesis of the inflammatory reaction is discussed, referring to the ionic change and the emigration of polymorphonuclear leucocytes to particles of plastics embedded in tissue.

Animals↗
PubMed1975

Starch and chemotaxis. A histological study in the mouse.

Primary interest in inflammation centers around the mechanism by which polymorphonuclear leucocytes emigrate from the circulating blood to an area of injury, a process apparently first designated as "chemotaxis" in 1888. Recent experimental studies have emphasized the role of ions in the pathogenesis of thrombi in the circulatory system following the implantation of plastics. The negatively charged leucocytes are attracted by positively charged plastics. Starch granules have a positive charge and, when implanted subcutaneously in the mouse, attract the negatively charged leucocytes. Sixty minutes after the subcutaneous implantation of starch granules in the subcutaneous tissue of mice polymorphonuclear leucocytes had begun to emigrate to the area. The number of leucocytes rapidly increased for 24 to 72 hours and then progressively decreased. By the 5th experimental day the number of leucocytes had decreased markedly and continued to decrease in their emigration to the granules of starch. The positive ionic charge associated with the granules of starch is neutralized by the adsorption of the negatively charged plasma protein ions. It is suggested that chemotaxis is an electrochemical phenomenon.

Animals↗
PubMed1975

Hairlessness in Mus musculus. A pathologic study.

The homozygous albino hairless mice at birth have hair bulbs and follicles the same as normal mice. Hairs develop and grow the same as in normal mice. However, about the sixth to eighth day hairs in the skin around the nose begin to disappear. This depletion of hairs continues over the head, neck, back, and abdomen of all mice in the same pattern. Essentially every hair over the entire body is absent macroscopically by the 30th to 40th day except for the vibrissae. A progressive atrophy of the hair bulbs and follicles is the basis for the absence of hairs after the first pelage. Only a rare follicle with a hair is present histologically in the adult mice. There are a few cysts in the dermis resulting from dilated residual hair follicles.

Albinism↗
PubMed1972

Bacteriological and pathological study of animals given Freund adjuvant.

Freund complete adjuvant, with allegedly "killed and dried" Mycobacterium butyricum added (intramuscularly in rabbits and intraperitoneally in mice), produced a local granulomatous lesion and frequently a similar lesion in the viscera. Acid-fast bacilli were present in these lesions, and in some animals M. butyricum was obtained in culture. When this culture was inoculated in mice, a similar lesion developed. Pathological lesions with similar acid-fast organisms also were observed by us in rabbits given Freund complete adjuvant by two other investigators.

Animals↗