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Biomedical subjects

J R Gorham

Publications and source records attributed to J R Gorham.

At least 37 records · Page 2Linked to original sources
PubMed1990

Comparison of a DNA probe, complement-fixation and indirect immunofluorescence tests for diagnosing Anaplasma marginale in suspected carrier cattle.

Most estimates of the prevalence of anaplasmosis have been based on serologic data using the complement-fixation (CF) and/or card agglutination tests. Since these tests are considered to be only about 50 percent reliable for detecting carrier cattle in enzootically stable herds, the need for more sensitive diagnostic tests is widely recognized. The objective in the present study was to compare the sensitivity of the CF test with that of the indirect immunofluorescence (IIF) test and a recently developed DNA probe in determining the prevalence of Anaplasma marginale infection in cattle from an enzootic area. The study herd consisted of 52 8-month-old steers and 13 3-year-old cows of mixed beef breed. All cattle were initially tested for this comparative purpose. All but one animal (one that was a positive reactor as assessed by all three tests, and served as a positive control), were treated with long-acting oxytetracycline in an attempt to clear any carrier infections. Each animal was then retested at 1 month and 2 months post-treatment (PT), in an effort to determine if the DNA probe could be used to evaluate the effectiveness of the drug. Six of the 65 (9.2%) initial serum samples were CF positive. In contrast, 60 (92.3%) and 64 (98.5%) of the samples were positive as assessed with the IIF test and the DNA probe, respectively. The DNA hybridization reactions varied in intensity within the sample population indicating different individual levels of infection. The DNA probe hybridized with two samples taken at 1 month PT, and with two different samples taken at 2 months PT. The mean IIF titers were reduced at both the 1 month and 2 month sampling times. These results suggest that the drug did not eliminate infections in all cattle. Some may have been cleared, but, in any event, the drug did reduce the level of infections below the sensitivity of the DNA probe and interrupted continuity of stimulation of antibody. Therefore, the DNA probe and the IIF test appear to be considerably more sensitive in detecting carrier infections than the CF test, and should be considered in future epidemiologic studies.

Anaplasma↗
PubMed1990

Organ-specific modification of the dose-response relationship of scrapie infectivity.

The dose-response relationships of scrapie strain 263K-infected hamster brain and spleen homogenates were compared to determine if intracerebral end-point titrations of infectivity in these homogenates were measures of the same pathogenic phenomenon. Analysis of the dose-response curves indicated that the average increase in incubation period per 10-fold dilution (i.e., the dilution kinetics) of brain infectivity was significantly different from that of spleen infectivity. This difference contradicted the assumption that the same pathogen or pathogenic mechanisms were responsible for producing disease in each titration. Therefore, the end-point titrations and infectivity titers of the brain and spleen homogenates were measures of two different phenomena. Subsequent passage of a scrapie-infected spleen homogenate demonstrated that the dose-response relationship of scrapie infectivity in this agent-host system was dependent on the organ titrated, not the tissue source or inoculation route of previous passage.

Animals↗
PubMed1990

Regulation of biotechnology in the United States and Canada.

The regulation of biotechnology in the United States and Canada is based on principles that reflect respect for the new technology, yet also recognize that most traditional approaches to regulation, employing sound science and common sense, still apply. Four specific principles form the framework on which regulatory schemes are based: (1) the products of biotechnology will not differ fundamentally from unmodified organisms or from conventional products; (2) the product rather than the process shall be regulated; (3) regulation should be based on the end use of the product and will be conducted on a case-by-case basis; and (4) the existing laws provide adequate authority for regulating the products of biotechnology. This report summarizes the regulatory approaches taken in various organisms and products. Special emphasis is given to: (1) issuance of entry permits for genetically-engineered plants and micro-organisms; (2) licensing of genetically-engineered veterinary biological products; and (3) permits for movement and release into the environment. A three-category classification system is described for dealing with hybridomas and recombinant-derived products, based on their biological characteristics and safety concerns. Categories range from relatively simple inactivated recombinant animal vaccines to products using live vectors to carry recombinant-derived foreign genes that code for immunizing antigens and/or other immune stimulants. This paper stresses that few fields of contemporary science and technology hold forth more possibilities and greater expectations than biotechnology. It is therefore of utmost importance that animal health officials and scientists ensure that the products of biotechnology will not cause or transmit infectious disease, adversely affect the environment or adulterate food products.

Animals↗
PubMed1990

Diagnosis of viral and bacterial diseases.

The potential contributions of techniques, such as restriction enzyme analysis, nucleic acid detection, the polymerase chain reaction and competitive inhibitive tests, are only beginning to be defined. The extraordinary promise of these procedures has yet to be fully realized. However, before these techniques are accepted and widely used, they should be shown to have sensitivity and specificity comparable to those of current tests. Finally, they should be safe, easy to conduct and automated to facilitate the study of large numbers of specimens.

Animals↗
PubMed1989

Canine parainfluenza virus-induced encephalitis in ferrets.

Young seronegative ferrets were intracerebrally inoculated with a neurotropic strain of canine parainfluenza (CPI) virus and serially killed at intervals after infection for subsequent viral immuno-peroxidase, light microscopical and scanning electron microscopical evaluation. The CPI virus infection resulted in a self-limiting non-suppurative ependymitis and choroiditis with associated ependymal cell degeneration. These changes were accompanied by paraventricular and perivascular cellular infiltrates of lymphocytes and monocytes, predominantly in the fourth ventricle and the cervical spinal cord and less frequently in the lateral ventricles and Sylvian duct. The inflammatory lesions were first detected on post-inoculation day (PID) 8 and had largely resolved after PID 22. Two animals showed multifocal axonal degeneration in the mesencephalon and vestibular nucleus, respectively. Immuno-histocytochemistry showed that virus replication was restricted to ependymal and subependymal cells and was most prominent on PID 4. No prominent residual lesions were present in convalescent animals. Virus-neutralizing CPI antibodies developed by PID 9 and increased slowly thereafter.

Animals↗
PubMed1988

Preliminary evaluation of praziquantel against metacercariae of Nanophyetus salmincola in chinook salmon (Oncorhynchus tshawytscha).

Praziquantel at dosages of 10, 20 or 100 mg/kg of body weight was evaluated against metacercariae of Nanophyetus salmincola in chinook salmon (Oncorhynchus tshawytscha). Ten salmon were used in each of four treated groups and 10 salmon were nontreated controls. Three wk after treatment, viability of metacercariae was determined by histologic evaluation, and by feeding the salmon to coyotes and subsequently determining the numbers of trematode eggs/g of feces and numbers of N. salmincola recovered at necropsy. Results of the experiment indicated that praziquantel at the dosages and routes of administration used was not effective against metacercariae in chinook salmon.

Animals↗
PubMed1988

Chronic disease in goats orally infected with two isolates of the caprine arthritis-encephalitis lentivirus.

Newborn Saanen goats were orally infected with two distinct biologically cloned isolates of the caprine arthritis-encephalitis lentivirus (CAEV), designated CAEV(63) (Crawford TB, Adams DS, Cheevers WP, Cork LC: Science 207:997, 1980) and CAEV (Co) (Cork LC, Hadlow WJ, Crawford TB, Gorham JR, Piper RC: J Infect Dis 129:134, 1974; Narayan O, Clements JE, Strandberg JD, Cork LC, Griffin DE: J Gen Virol 50:69, 1980). All infected goats seroconverted for antibodies to CAEV, and there were no serologic reversions. Histologic lesions consisted of chronic inflammation of variable incidence and severity in joints and mammary gland. Clinical arthritis, estimated by enlargement of carpi, correlated with severe inflammation of radiocarpal synovium. Statistical evaluations of clinical and histologic parameters indicated that chronic joint disease was significantly more frequent and more severe in the group of goats infected with CAEV(63) than in the group infected with CAEV (Co). Thus, the severity of chronic arthritis is determined in part by the relative pathogenicity of individual CAEV isolates. Analysis of the temporal development of carpal arthritis during the first 3 years of infection indicated that (a) the extent of eventual chronic disease in individual joints was apparent relatively early after infection, (b) joints with severe chronic lesions were clinically enlarged at irregular intervals and (c) the pattern of recurrent arthritis was unique for each joint. Thus, chronic arthritis develops with a progressive course which may be promoted by recrudescent inflammation. Infectious virus was recovered 3 years after infection from selected tissues of 12 of 17 CAEV(63)-infected goats and 11 of 18 CAEV(Co)-infected goats. Virus recovery was independent of the virus isolate used for experimental infection and did not correlate with the severity of lesions.

Administration, Oral↗
PubMed1988

Comparison of an enzyme-linked immunosorbent assay and a complement-fixation test for the detection of IgG to bovine herpesvirus type 4 (bovine cytomegalovirus).

An indirect ELISA for the detection of bovine immunoglobulin to bovine herpesvirus type 4 (BHV-4) was developed. Three methods of antigen preparation were compared. They included (1) BHV-4-infected Madin Darby bovine kidney (MDBK) cells treated with glycine and then frozen and thawed, (2) BHV-4-infected MDBK cells treated with glycine and then sonicated, and (3) BHV-4-infected MDBK cells treated with a detergent. The antigen preparation that gave the highest reactivity was the first method. We obtained serum samples from 178 cattle in the field and assayed the serum by ELISA and the complement-fixation (CF) test. Eighty-six percent (153) of the serum samples were positive by ELISA, and 70% (124) were positive by the CF test. The ELISA had a higher degree of sensitivity than did the CF test. Also, the ELISA was specific, and the prevalence of BHV-4-infection was more common in beef and dairy herds than previously recognized.

Animals↗
PubMed1988

Evaluation of praziquantel against induced Nanophyetus salmincola infections in coyotes and dogs.

Efficacy of praziquantel against Nanophyetus salmincola, the trematode vector of salmon poisoning disease, was determined in coyotes (n = 29) and dogs (n = 25). The 10- to 14-week-old animals were fed fish or fish kidneys that contained metacercariae of N salmincola. To prevent salmon poisoning disease, all animals were treated with tetracycline on days 8 and 9 after they were fed fish. Ten days after ingestion of infected fish, 19 coyotes and 12 dogs were treated once with praziquantel, administered SC or IM, at dosages between 6.68 and 38.73 mg/kg of body weight. Within 8 days after treatment, the numbers of trematode eggs in feces and trematodes recovered from the small intestine were reduced by greater than 99% when compared with untreated controls. Signs of drug toxicosis were not observed. On the basis of these results, praziquantel at doses approved for use in dogs against cestodes was highly effective against N salmincola in coyotes and dogs.

Animals↗
PubMed1987

Effects of induced thrombocytopenia on viral invasion of the central nervous system in canine distemper virus infection.

Groups of canine distemper virus (CDV) susceptible ferrets were treated daily with 2.0 ml of normal goat serum (NGS) or goat anti-ferret platelet serum from 2 days before to 11 days after infection. Each group was subdivided into 2 and one subgroup of each was subsequently injected intraperitoneally with virulent R252-CDV. Ferrets were killed on days 2, 4, 6, 9 and 11 after infection and tissues from the central nervous system (CNS) were examined for histopathological lesions typical for CDV and also of CDV antigen by indirect immuno-fluorescence methods. In NGS-treated animals, a time course-dependent spread of CDV from CNS endothelium during days 2 to 4 after infection through choroid plexus epithelium was observed. In contrast, CDV-infected ferrets treated with anti-platelet antibody exhibited a delay in infection of CNS endothelium until 9 days after infection. The results of this study confirm vascular endothelium as the primary route of invasion of CNS tissues by CDV and implicate the circulating platelet in the initiation of this event.

Animals↗
PubMed1987

The development and analysis of species specific and cross reactive monoclonal antibodies to leukocyte differentiation antigens and antigens of the major histocompatibility complex for use in the study of the immune system in cattle and other species.

We examined the potential of developing a set of species specific and cross reactive monoclonal antibodies (MoAbs) for use in the study of the phylogenetic and functional relation of class I and class II antigens of the major histocompatibility complex (MHC) and leukocyte differentiation antigens in cattle and other species. Comparing immunization strategies demonstrated the number of hybrids producing cross reactive antibodies can be increased by hyperimmunization of mice with lymphoid cells from multiple species. Comparing various methods of assay (antibody-complement mediated cytotoxicity [CT], enzyme linked immunosorbent assay [ELISA] and flow microfluorimetry [FMF]), revealed FMF is the most useful technique for the primary assay of hybridomas producing MoAbs of potential interest. By using dual parameter and dual fluorescence analysis, we could determine whether a given MoAb reacted with mononuclear cells (lymphocytes and monocytes) and/or granulocytes, and also whether any two MoAbs of different isotype and specificity recognized antigens present on identical or separate populations of leukocytes. Comparing the patterns of MoAb reactivity with leukocytes obtained from cows, goats, sheep, pigs, horses and humans, as well as comparing the patterns of reactivity with a panel of lymphoid cell lines derived from cattle (with enzootic bovine leukemia) and humans (with various forms of leukemia), revealed sets of MoAbs reactive with unique antigenic determinants present on BoLA class I (15 MoAbs) and class II (9 MoAbs) antigens, and also MoAbs reactive with determinants present on leukocyte differentiation antigens (36 MoAbs). Dual fluorescence analysis demonstrated the antigens detected by some MoAbs are predominantly expressed on one lineage of leukocytes while others are expressed on two or more lineages of leukocytes. Dual and single fluorescence analysis also demonstrated the PNA receptor(s) is: expressed on T cells, granulocytes and class II antigen monocytes and absent or expressed in low amount on sIgM+ B cells and a newly defined Non T/Non B population of cells. The strategies described for identifying and analyzing the specificity of MoAbs demonstrate the feasibility of developing a set of cross reactive MoAbs for identifying homologous molecules in multiple species and delineating their functional and phylogenetic relation.

Animals↗
PubMed1987

Salmon poisoning disease in juvenile coyotes: clinical evaluation and infectivity of metacercariae and rickettsiae.

Clinical salmon poisoning disease (SPD), and survival of Neorickettsia helminthoeca and metacercariae of Nanophyetus salmincola in fish were evaluated experimentally in 12-wk-old coyotes (Canis latrans) to determine the potential of SPD for biological control of coyotes. Coyotes readily ate fish that contained metacercariae and rickettsiae. They developed diarrhea, anorexia and lethargy within 7 days after feeding. Infected coyotes lost 58% of their body weight when compared to uninfected controls. They died or became moribund and were euthanatized within 17 days after feeding. Rickettsiae were present in the macrophages of lymph nodes of all affected coyotes. Clinical disease occurred in coyotes fed fresh fish, but not in coyotes fed fish stored at 4 C for greater than or equal to 30 days or at -20 C for 14 days. Metacercariae in fish were viable after 60 days at 4 C. These trematodes developed in coyotes, but clinical SPD did not occur. This indicated survival of metacercariae, but not rickettsiae. Metacercariae were not viable after 14 days at -20 C.

Animals↗
PubMed1987

Comparisons of feline panleukopenia virus, canine parvovirus, raccoon parvovirus, and mink enteritis virus and their pathogenicity for mink and ferrets.

Parvoviruses from mink (mink enteritis virus [MEV]), cats (feline panleukopenia virus [FPV]), raccoons (raccoon parvovirus [RPV]), and dogs (canine parvovirus [CPV]) were compared. Restriction enzyme analysis of the viral replicative-form DNA revealed no consistent differences between FPV and RPV isolates, but CPV and MEV isolates could be distinguished readily from other virus types. Feline panleukopenia virus, RPV, and MEV, but not CPV, replicated to high titers in mink. However, on the first passage, disease and microscopic lesions were observed only in mink inoculated with MEV. Feline panleukopenia virus and RPV isolates replicated in ferrets, but disease or microscopic lesions were not observed. Feline panleukopenia virus and RPV isolates could be passaged repeatedly in mink and ferrets. Virulence of FPV and RPV isolates was low compared with that of MEV, and only a single mink inoculated with FPV or with RPV developed clinical disease on the sixth passage of virus.

Animals↗
PubMed1987

Efficacy of Corynebacterium pseudotuberculosis bacterin for the immunologic protection of sheep against development of caseous lymphadenitis.

The efficacy of a Corynebacterium pseudotuberculosis bacterin to protect sheep immunologically against development of caseous lymphadenitis was evaluated in controlled challenge-exposure experiments. Sixty-three mixed-breed, white-faced lambs were used. The lambs were 10 to 12 weeks old and were randomly assigned to 3 groups (21 lambs/group). Group 1 was vaccinated once, using 2 ml of a C pseudotuberculosis bacterin (given subcutaneously) in the right axillary region at the beginning of the study. Group 2 was vaccinated twice; the 1st vaccination was given at the same time that lambs in group 1 were vaccinated and the 2nd vaccination was given 4 weeks later. Group 3 (nonvaccinated controls) was given physiologic saline solution (2 ml, subcutaneously). Each lamb was challenge exposed (ie, given 2 ml of live Corynebacterium pseudotuberculosis inoculum [6 X 10(6) colony-forming units/ml], subcutaneously at 4 different sites) during the 20th week of the study. All lambs were killed and necropsied during week 33. The mean number of abscesses per lamb was 7 for group 1, 4 for group 2, and 32 for group 3. Significant differences in the size of the abscesses were not found between the groups. Results of the study indicated that the vaccine provided immunologic protection of lambs against challenge exposure to Corynebacterium pseudotuberculosis.

Animals↗
PubMed1987

Canine distemper virus: in vivo virulence of in vitro-passaged persistent virus strains.

Groups of ferrets were inoculated intraperitoneally with cell lysates or equivalent doses of whole cells from 9 different cell lines persistently infected with canine distemper virus. Viral persistence in these cell lines was characterized by noncytolytic infection and restricted release of cell-free infectious virus. In vivo replication competency of the various viruses in ferrets ranged from nil to virulent and did not correlate with in vitro titers of inocula. Ferret virulence (cell lysates only) for one cell line (CCL64-RCDV) was associated with morphologic absence of virion assembly, failure to interfere with lytic virus replication after superinfection, and in vitro infectivity restricted to canine macrophage-like tumor cells. Virion protein production in the CCL64-RCDV virulent inoculum and in the CCL64-Ly avirulent inoculum was evaluated by use of the immunoblot technique. All major virion proteins were produced by infected cells. Virulence was not associated with obvious changes in electrophoretic mobility of virion proteins when profiles of ferret-virulent CCL64-RCDV were compared with those of avirulent CCL64-Ly.

Animals↗
PubMed1986

Ineffectiveness of clorsulon against Nanophyetus salmincola in coyotes.

Efficacy of clorsulon against the trematode Nanophyetus salmincola was evaluated in coyotes. Ten 16-week-old coyote pups were fed fish that contained metacercariae of N. salmincola. Twenty-one days later, 5 of the coyotes were given a suspension of clorsulon (approx 16 mg/kg of body weight, orally). Within 30 days after treatment, the numbers of fluke eggs in fecal specimens from the 5 treated coyotes had not decreased, and numbers of fluke eggs and flukes recovered from treated coyotes at necropsy did not differ from numbers of fluke eggs and flukes recovered from 5 untreated coyotes. Therefore, clorsulon at a dosage of 16 mg/kg was not effective against N. salmincola.

Animals↗
PubMed1986

Vaccines and principles of immunization.

This article discusses the production of the various classes of vaccines and compares the advantages and disadvantages of each. Adjuvants, combination vaccines, heterologous viral vaccines, and vaccination failure are discussed briefly. Reported adverse reactions to vaccination are described at length. Essential vaccination for several exotic species is given.

Animals↗