Degree Of Host Response Research Articles

Modulation of growth performance in disease: reactive nitrogen compounds and their impact on cell proteins

During life, all animals encounter situations that challenge their capability for optimal growth. In reacting to immune challenges in the form of disease, homeostatic mechanisms attempt to overcome disharmony of the body’s internal environment, or simply put, stress. The overall impact of stress revolves around a dynamic relationship between the level of challenge imparted on physiological systems and the degree of host response that is mounted in the process of detecting and reacting to the stress. In growing animals, the majority of milder stress encounters are manifest in terms of energetic inefficiencies and periods of reduced anabolism. In contrast, severe stress is often characterized by frank catabolism and tissue wasting. In some instances a level of stress (that might be termed a “stress breakpoint”) is reached at which time the host response itself contributes to the cascade of negative effectors that further cause illness. These “breakpoint” responses are characterized by more intense acute responses to stress or a much more protracted duration of the response than would be expected given the nature of the stress. Key to understanding how growth in the young animal responds to infectious stresses is the recognition that (a) when immune responses that normally maintain health go awry, the reporters and effectors of the immune system (cytokines and the nitric oxide cascade) can contribute to stress disease processes and (b) reactive nitrogen compounds derived from the nitric oxide, as well as super oxide anion can modify intracellular proteins and block otherwise normal biochemical processes that regulate cell function. A key example of this is the loss of regulation of IGF-I by GH. As animals react more severely to disease stress, IGF-I concentrations in plasma decline progressively. Recent data derived from (LPS) challenges performed on young calves suggest that the prolonged decline in IGF-I is associated with the development of hepatic cytotoxicity localized to regions of protein nitration as identified by immunohistochemistry. Identifying biochemical criteria for disease processes provides needed guidance for the further development of intervention strategies to limit the impact of disease on growth.

Onchocerciasis: clinical presentation and host parasite interactions in patients of southern Sudan.

Onchocerciasis, an infection by the filarial nematode Onchoverca volvulus, is widely distributed in tropical Africa and of great dermatologic interest. This study analyses the dermatologic presentation and tries to determine the correlations between clinical disease and host parasite interactions in onchocerciasis patients of the Southern Sudan. We performed clinical and histopathologic investigations in patients with onchocerciasis in the Wau District, Bahr el Ghazal Province, Southern Sudan. As well as a detailed clinical skin examination, skin biopsies were taken, processed, and investigated for type and degree of host tissue response. Parasitologic, clinical, and histopathologic findings were evaluated. Onchocerciasis appears with a variety of severe skin lesions. Central is a pruritic rash. Long-standing cases develop extensive pigmentary changes and impressive signs of skin tissue exhaustion. Cellular host tissue responses to degenerating skin microfilariae seem to play a key role in the development of skin pathology. The degree of host response appears to be inversely proportional to the host's microfilarial load. Onchocerciasis represents a health problem of great dermatologic importance in Southern Sudan. The study results demonstrate clinical variations in onchocerciasis and provide support for the existence of a disease spectrum.

Squamous carcinoma in scars: clinicopathological correlations.

Twelve cases of squamous cell carcinoma arising in scars of the skin are analyzed. Correlation of tumor aggressiveness, tumor differentiation, intensity of small lymphocyte infiltration, and nature of adjacent collagen tissue to tumor stroma was investigated. All tumors were predominantly well differentiated. Nine patients had no metastasis or recurrence after surgical treatment of the primary tumor. Three patients developed widespread metastases and died less than 2 years after operation. The tumors of these latter patients contained areas of pleomorphic and spindle cells and had minimal infiltrates of small lymphocytes. In contrast, the 9 patients who remained free of tumor had moderate infiltrates of small lymphocytes, and in just 1 of 9 was an area of pleomorphic tumor cells found. Prognosis in scar carcinoma, therefore, may be related to tumor differentiation and the degree of host response with small lymphocytes to the tumor, rather than to the universally poor prognosis recorded in the past.

Nonenzymic Histochemistry of Bovine Abomasal Tissue Infected with Ostertagia ostertagi

Abomasa from calves infected with 0. ostertagi and 0. radiatum, 0. radiatum only, and an uninfected calf were studied histochemically at 2, 5, 7, 14, and 22 days after infection (DAI). Collagen, accompanied by fibroblasts, was deposited in the tissue about the dilated gastric glands beginning at 7 DAI. Structural fibers staining with reticulum stains were abundant about the necks of the infected gastric glands. Compared to uninfected tissue and tissue adjacent to the dilated gastric glands, fewer chief cell granules stained for tryptophan, SS bonds, and SH groups immediately about the dilated gastric glands from 2 through 22 DAI. The cytoplasm of chief cells, agranular leukocytes, and fibroblasts stained intensely for RNA in uninfected and adjacent tissue, whereas degenerating chief cells immediately about the dilated gastric glands stained less intensely beginning at 7 DAI. Hemoand lipofuchsin methods stained a PAS-positive iron-negative pigment in macrophages and degenerating cells in infected abomasa. Frandsen (1965) studied the nonenzymic histochemistry of oesophagostomiasis at 8 and 10 days and ostertagiasis at 8 days postinoculation. He observed no significant changes in the histochemistry of abomasal tissue infected with 0. ostertagi probably because of an absence of intimacy between the larvae of 0. ostertagi and abomasal tissue. Because intimacy of the parasite with host tissues might influence the time and degree of host response, it became pertinent to extend the period of infection and reinvestigate the nonenzymic histochemistry of bovine ostertagiasis emphasizing ground substance, structural proteins, and fibers. The histochemical data were interpreted relative to the observed pathology which was similar to that described by Ritchie etal. (1966). MATERIALS AND METHODS Abomasa from 5 calves, infected with 350, 350, 150, 75, and 150 thousand larvae of 0. ostertagi, were removed at 2, 5, 7, 14, and 22 days after inoculation (DAI), respectively. All calves were 7 months old, except the third calf which was 9 months old. At necropsy, tissues were excised from proximal and distal parts of the abomasum and fixed in (1) neutral buffered formalin, (2) formol-calcium, (3) Bouin's, (4) Carnoy's, and (5) Zenker's fixatives. Hereafter, the histochemical method will be followed by a number designating the kind of fixation used. Additional tissues were quenched at -70 C in isopentane, cooled with dry ice, and stored in screw-cap vials on dry ice. Received for publication 17 May 1973. *Animal Parasitology Institute, ARS, Beltsville, Maryland 20705. Because these calves were also infected with Oesophagostomum radiatum for other studies, control tissues consisted of abomasal tissue from a calf infected with 20,000 0. radiatum larvae only and from an uninfected calf. Where appropriate, calf tissue positive controls were processed and studied concurrently. To verify the appropriate larval stage in tissue, whole mounts of 0. ostertagi were cleared in dimethylsulfoxide (DMSO) and compared with stages described and illustrated by Douvres (1956).

The development of acquired resistance and age resistance to Nematodirus battus in the laboratory rabbit.

Four groups of 8 rabbits were infected with a range of doses of N. bath's larvae. The percentage recoveries of worms from groups receiving 100 and 1000 larvae were significantly greater than those from groups receiving 10000 and 50000 larvae. It is suggested that the worm population density is dependent on the degree of host response stimulated by the initial larval dose.Experience of a chemically abbreviated patent infection of N. batlus gave significant protection to a group of 8 rabbits against establishment of worms from subsequent challenge compared with inexperienced controls.Rabbits aged 5 months and 11 weeks were as susceptible to the establishment of worms as rabbits aged 7½ weeks; but age resistance vas manifested by the greater proportion of worms which developed to the fifth stage in the worm populations of the youngest group than in the other 2 groups.