PubMed Health⌕ Search

Biomedical subjects

R H Jacobson

Publications and source records attributed to R H Jacobson.

At least 73 records · Page 4Linked to original sources
PubMed1985

Variable persistence of the contagious equine metritis organism in the genital tract of CBA/J, CBA/N, LAF1/J, BALB/c and congenitally thymus-deficient (nude) mice.

Five inbred strains of mice, CBA/J, CBA/N, LAF1, BALB/c and congenitally thymus-deficient nude mice of BALB/c background, varied considerably in their susceptibility to the contagious equine metritis organism (CEMO). Whereas all the strains were virtually refractive to vaginal challenge, LAF1 and CBA/N mice were readily infected by intra-uterine inoculation. Based on infection rate and nature of the bacteriological response, CBA/N mice appeared the more susceptible of the 2 strains. Attempts to transmit CEMO to thymus-deficient nude mice were unsuccessful by both of these routes of challenge and by intraperitoneal inoculation, indicating that host resistance to the causal agent is independent of thymus-mediated immune phenomena. No clinical evidence of infection was observed in any of the experimentally infected mice. Although persistence of CEMO in the female reproductive tract varied widely, it could be isolated from some of the CBA/N mice for as long as 19 weeks after challenge by the intra-uterine route. The organism was cultured from the ovaries and/or oviducts of a high percentage of one group of CBA/N mice after 50 days, when it could no longer be recovered from the remainder of the genital tract. Limited attempts to achieve venereal transmission of CEMO between culture-positive female and companion male CBA/N mice were unsuccessful. The relative susceptibility of the CBA/N strain of mice to CEMO would suggest that host resistance to this infection is at least partly dependent on the presence of a fully functional B lymphocyte system. Further studies in this experimental model may elucidate some of the immunological mechanisms underlying development of resistance in the horse, more specifically as they relate to the occurrence of the carrier state in this disease.

Animals↗
PubMed1985

Experimental inoculation of cats with human coronavirus 229E and subsequent challenge with feline infectious peritonitis virus.

Minimal-disease cats exposed to live human coronavirus 229E developed homologous antibody responses that suggested little or no replication of the virus in inoculated animals. Oronasal and subcutaneous inoculation of coronavirus 229E did not elicit an antibody response by heterologous (transmissible gastroenteritis virus, canine coronavirus) neutralization or by heterologous (transmissible gastroenteritis virus) kinetics-based enzyme-linked immunosorbent assay. No clinical signs attributable to coronavirus 229E were seen in inoculated cats. Although the number of animals in each of the five experimental groups was small (n = 2), antibodies produced in response to the virus did not appear to sensitize cats to subsequent feline infectious peritonitis virus challenge, but neither did they cross-protect cats against the challenge dose.

Animals↗
PubMed1985

Loa loa: antibody responses in experimentally infected baboons and rhesus monkeys.

Antibody responses to Loa loa in experimentally infected baboons and rhesus monkeys were measured using an adult L. loa antigen in a kinetic enzyme-linked immunosorbent assay. Animals were infected with infective stage larvae or by transplantation of juvenile worms. There were no differences between host species in antibody response and there was no relationship between adult worm numbers recovered at necropsy and antibody level. Antibody levels tended to be inversely correlated to the number of circulating microfilariae and decreased concommitant with the onset of patency. Following an initial wave, suppression of the microfilaremia was observed. Although the microfilaremia recrudesced following splenectomy, no changes in the antibody levels were noted pre or postsplenectomy. An antibody response was not demonstrable in baboons infected by transplantation of juvenile worms. Although a primary suppression of the microfilaremia by the spleen still occurred.

Animals↗
PubMed1984

Transmissibility of the contagious equine metritis organism for the cat.

A group of SPF cats were moderately susceptible to the causal organism of contagious equine metritis (CEM) following intra-uterine or intrapreputial challenge with an Irish streptomycin resistant strain isolated from a clinically infected mare. Subclinical infections were established in only 50% of the cats, none of which became long-term carriers of the organism. Cytological examination of vaginal smears was of no diagnostic value in confirming infection in inapparently infected cats. Bacteriological responses after primary or secondary challenge with the CEM organism were essentially similar, with one exception, a female cat in which there was possible evidence of local immunity persisting after the primary infection. Efforts to reactivate shedding subsequent to the immediate post-challenge period were unsuccessful. Throughout the experimental period, the cats remained sero-negative to the complement-fixation test, and they failed to develop any significant increase in the levels of antibody activity as measured by the kinetics-based ELISA or KELA system. On day 89 after primary challenge, the cats were euthanized and various sites in the genitourinary tract and the internal iliac lymphatic glands subjected to bacteriological and pathological examination for evidence of CEM infection with negative results. The findings of this study, although establishing the transmissibility of the CEM organism for the cat, demonstrate the limited value of this species as an experimental model system for the disease in the horse.

Animals↗
PubMed1984

Role of recent vaccination in production of false-positive coronavirus antibody titers in cats.

Statistical support was obtained for an association between recent vaccination of cats and the presence of elevated background (i.e., anti-cell culture) reactivity in certain of their sera, as detected with a kinetics-based enzyme-linked immunosorbent assay for coronavirus antibodies, implicating routine vaccination as a potential cause of false-positive antibody test results.

Animals↗
PubMed1984

Comparison of Schistosoma mansoni migration patterns in normal and irradiated cercaria-immunized mice by means of autoradiographic analysis. Evidence that worm elimination occurs after the skin phase in immunized mice.

Migration and elimination of radiolabeled Schistosoma mansoni were compared in naive and irradiated cercaria-immunized mice by autoradiography of compressed host tissues. The results indicated that 1) most of the normal elimination of schistosomula in unimmunized mice and the additional elimination in immunized mice occur at some point(s) after arrival of schistosomula in the lungs and before their development into adult worms, 2) migration of schistosomula from skin to lungs is delayed for several days but not reduced in immunized mice, 3) migration of schistosomula from lungs to liver is delayed for several days in immunized mice, and 4) schistosomula reach the liver in reduced numbers or are killed and cleared in the liver in greater numbers in immunized mice. The lung chop procedure was shown to recover schistosomula from control and irradiated cercaria-immunized mice with equal efficiency. Autoradiography of all tissues of the body demonstrated that, in both control and immunized mice, at least 20-25% of the schistosomula detectable 2 and 3 weeks after infection were present in tissues other than the skin, lungs and liver.

Animals↗
PubMed1984

Experimental inoculation of cats with canine coronavirus and subsequent challenge with feline infectious peritonitis virus.

Oronasal inoculation of minimal-disease cats with a virulent field isolate of canine coronavirus elicited a neutralizing antibody response that increased steadily over a two-month period, indicating in vivo amplification of the inoculated dose. A heterologous neutralizing antibody response to transmissible gastroenteritis virus could be detected three weeks after titers to canine coronavirus were first observed and was found to parallel the homologous response at a level approximately one log10 dilution lower. A modest anamnestic response detectable in both assays was observed after a second exposure to canine coronavirus. Cross-reacting antibodies to transmissible gastroenteritis virus were not detected by a kinetics-based enzyme-linked immunosorbent assay (KELA), however, until after cats had received multiple daily doses of canine coronavirus (third exposure). No clinical signs attributable to canine coronavirus were seen in inoculated cats, and virus could not be isolated from fecal or rectal swabs nor identified in fecal specimens by electron microscopy. Both virus-neutralizing and KELA titers were boosted by aerosol challenge with feline infectious peritonitis virus. Antibodies produced in response to canine coronavirus did not sensitize cats to subsequent feline infectious peritonitis virus challenge, but neither did they protect cats against the challenge dose.

Animals↗
PubMed1983

Immune response to porin in cattle immunized with whole cell, outer membrane, and outer membrane protein antigens of Brucella abortus combined with trehalose dimycolate and muramyl dipeptide adjuvants.

The immune response of cattle to nonliving vaccines derived from Brucella abortus rough strain 45/20 was studied. Vaccines contained trehalose dimycolate and a derivative of muramyl dipeptide. N-acetylmuramyl-L-alpha-aminobutyryl-D-isoglutamine. A factorial experiment was designed to test the effects of type of antigen, quantity of antigen, and quantity of mineral oil on the immune response to porin. Muramyl dipeptide was kept constant at 5 mg per dose, and 1 part of trehalose dimycolate was incorporated for two parts of dry matter. Over a 10-week period, blastogenesis responses to porin were largest in cattle immunized with outer membranes; the highest antibody titers to the porin-lipopolysaccharide complex were achieved by immunization with detergent-extracted outer membrane proteins. There was no advantage in the use of 25, rather than 5, mg of any of the antigens, but antibody responses were improved by increasing the quantity of oil from 0.6 to 1.8 ml per dose. In other animals, blastogenesis and antibody responses were sustained at high levels longer than 3 months after two vaccinations with outer membrane proteins. Intradermal injection of porin evoked inflammatory reactions histologically consistent with delayed-type hypersensitivity. Cross-reactions in cases of delayed-type hypersensitivity occurred with porin derived from a smooth strain of B. abortus but were less extensive than in the blastogenesis test. The magnitude of the delayed-type hypersensitivity and blastogenesis responses induced by vaccination exceeded those observed after natural or experimental infections. No ill effects were observed after vaccination. These findings provide a basis for the use of trehalose dimycolate and muramyl dipeptide adjuvants in evaluating nonviable vaccines for bovine brucellosis.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1983

Evaluation of a computer-assisted, kinetics-based enzyme-linked immunosorbent assay for detection of coronavirus antibodies in cats.

A computer-assisted, kinetics-based enzyme-linked immunosorbent assay was adapted for the detection of coronavirus antibodies in feline serum. An alkaline antigen diluent (carbonate-bicarbonate buffer, pH 9.6) used in initial experiments produced diffuse, nonspecific color reactions in both viral and control antigen cuvettes which were correlated, paradoxically, with coronavirus antibody levels in test sera. These interfering reactions were minimized by use of lower-pH antigen diluents such as water and phosphate-buffered saline. Background kinetics-based enzyme-linked immunosorbent assay reactivity directed against a noncoronaviral component of antigen tissue culture fluids could then detected in numerous sera, particularly in samples with lower titers. Much of this reactivity was shown to be associated with bovine gamma globulins in cell culture fluid. It was not serum lot or species specific, since a variety of bovine serum lots as well as individual lots of serum from other mammalian and avian species reacted. Reactivity was markedly reduced when cells for antigen preparation were grown in gamma globulin-free bovine serum. Generation of corrected slope values from the kinetics-based enzyme-linked immunosorbent assay made it possible to correct for residual background reactivity in individual test sera and thus eliminate a potentially major source of false-positive reactions. Collectively, these studies indicated that the control of nonspecific reactivity in feline coronavirus serology is absolutely essential to obtain useful estimates of specific antibody responses.

Animals↗
PubMed1983

Macrotiter assay for coronavirus-neutralizing activity in cats using a canine continuous cell line (A-72).

A heterologous neutralization assay for feline infectious peritonitis virus serology was developed using a single continuous cell line of canine origin, A-72, which is susceptible to cytopathic infection with both transmissible gastroenteritis virus of pigs and canine coronavirus. Of several coronavirus isolates tested, the 1-71 isolate of canine coronavirus demonstrated the most effective neutralization by serum and body fluids of cats with histopathologically confirmed feline infectious peritonitis.

Animals↗
PubMed1983

Effects of various anthelmintics on larval stages of Nematospiroides dubius (Nematoda).

The effects of six anthelmintics on larval stages of Nematospiroides dubius in mice were assessed. Levamisole phosphate, at a dose of 100 mg/kg administered per os 6 days postlarval inoculation (PI), effected greater than 98% reduction in worm burdens. At dose rates one log2 higher, 50% mortality of the mice occurred. Ivermectin, given per os at a dose rate of 5 mg/kg, removed all of the worms when administered either on Day 3 or 6 PI. No toxicity was observed even at the highest dose tested (25 mg/kg). Albendazole, cambendazole, pyrantel pamoate, and fenbendazole, all given per os at a dose of 100 mg/kg on day 6 PI, allowed from 52 to 75% of the worms to develop to adulthood. Ivermectin emerged as the larvicidal drug of choice owing to its high efficacy and undetectable toxic side effects.

Animals↗
PubMed1982

Computer-assisted enzyme immunoassays and simplified immunofluorescence assays: applications for the diagnostic laboratory and the veterinarian's office.

A computer-assisted enzyme-linked immunosorbent assay (ELISA) system, based on kinetics of the reaction between substrate and enzyme molecules, was developed for testing large numbers of sera in laboratory applications. Systematic and random errors associated with conventional ELISA technique were identified leading to results formulated on a statistically validated, objective, and standardized basis. In a parallel development, an inexpensive system for field and veterinary office applications contained many of the qualities of the computer-assisted ELISA. This system uses a fluorogenic indicator (rather than the enzyme-substrate interaction) in a rapid test (15 to 20 minutes' duration) which promises broad application in serodiagnosis.

Animal Diseases↗
PubMed1982

Immunodeficiency models in characterization of immune responses to parasites--an overview.

The use of selected immunosuppressant agents and genetically immunodeficient animals in studies designed to characterize the immune response to parasitic infections is reviewed. Immunosuppression induced by commonly used chemicals (corticosteroids and alkylating agents) and ionizing radiation is examined briefly. A greater emphasis is placed on congenitally immunodeficient animals and on immunosuppression induced by purified antisera directed against a variety of cellular specificities. The use of such immunodeficient animals has aided our understanding of the complex interrelationship between host and parasite. However, chemical immunosuppressants and the levels of irradiation used in adoptive cell transfer studies are usually indiscriminant in their toxic effects on a variety of tissues other than those targeted. These affected tissues may be crucial in establishment of the delicate physiological balance required for maintenance of equilibrium between host and parasite. Thus the effects of cytotoxic drugs or irradiation on parasite burdens may reflect alteration of not only immunity, but other essential factors leading to misinterpretation of results. Use of congenitally immunodeficient animals, which are readily repaired by introduction of specific cellular components, may be more useful in dissecting host responses to parasites. In addition, depletion of specific components of the immune system through use of anti-isotype antiserum, for example, is another useful probe. These approaches do not suffer from the generalized cytotoxic effects of chemicals and irradiation, and remove a potentially important and misleading variable from experimental designs. They also allow one to discriminate between non-specific inflammatory and specific immunological factors. The potential pitfalls of broadly used induced immunodeficiency states in studies on parasitisms may now be overcome at least partially by use of highly purified and specific cytotoxic reagents coupled with an ever-increasing array of genetically immunodeficient animal models.

Adrenal Cortex Hormones↗
PubMed1982

Immunity to Nematospiroides dubius: parasite stages responsible for and subject to resistance in high responder (LAF1/J) mice.

In the LAF1/J mouse strain, a single prior exposure to infective larvae of N. dubius given per os resulted in greater than 90% reduction of an homologous larval challenge; in contrast, a single larval sensitizing infection had no effect on adult worms introduced directly into the duodenum via laparotomy. The LAF1/J mice given a single sensitizing infection of adult worms via laparotomy did not exhibit resistance to homologous challenge of either infective larvae or adult worms. Because all sensitizing infections were removed chemotherapeutically before administration of challenge inocula, potential effects of "overcrowding" on establishment or development of challenge infections were precluded. Worm-specific antibody determinations indicated that adult worms introduced into the gut lumen did not prime the host for a secondary response to a challenge by larval or adult worms. However, a challenge with larvae of mice previously sensitized with an homologous larval infection, did stimulate an anamnestic antibody response. Collectively, the data indicated that in a highly responsive mouse strain (LAF1/J), larval stages were requisite in stimulation of host resistance to reinfection and a larval challenge was fully susceptible to the effects of that response. Mature adult worms apparently did not stimulate nor were they susceptible to the host's immune response.

Animals↗
PubMed1981

Quantitative fluorescent immunoassay for measurement of antibody to Dirofilaria immitis in dogs.

An automated fluorescent immunoassay technique (FIAX; International Diagnostic Technology, Santa Clara, Calif.) has been developed for the quantitation of circulating antibodies in dogs infected with Dirofilaria immitis. Two groups of sera, group I consisting of 77 samples and group II consisting of 126 samples, were obtained from experimentally infected microfilaremic dogs, known negative controls, and clinically diagnosed cases of occult dirofilariasis. Antibody against a partially purified trichloroacetic acid-soluble extract of a soluble somatic extract of D. immitis was measured by FIAX and by an enzyme-linked immunosorbent assay (ELISA). A standard curve was drawn from four samples with known FIAX titers and fluorescent signal unit values. The standard curve was used to determine titers of unknown samples. The correlation coefficients determined in the analysis of log10 ELISA and log10 FIAX values were r = 0.9057 and r = 0.8976 in groups I and II, respectively. Eighty-three percent of the titer values calculated by FIAX in group I were within one dilution, and 95% were within two dilutions, of those titers obtained by ELISA. In group II, 79 and 96% of the values obtained by FIAX were within one and two dilutions, respectively, of those obtained by ELISA. FIAX proved to be a reproducible and convenient assay for the measurement of serum antibody in dogs experimentally infected with Dirofilaria.

Animals↗