Search PubMed⌕ Search

Biomedical subjects

J C Williams

Publications and source records attributed to J C Williams.

At least 271 records · Page 15Linked to original sources
PubMed1987

Efficacy of levamisole and netobimin against Haemonchus contortus in lambs in Louisiana.

Efficacy of levamisole was evaluated in a suspected levamisole-resistant population of Haemonchus contortus in the Louisiana State University sheep flock. The efficacy of netobimin also was evaluated against this population of Haemonchus. In trial 1, 5 lambs naturally infected with H contortus were given 8 mg of levamisole/kg of body weight as a drench, and 5 lambs were not treated (controls). Nematode recovery after slaughter indicated 0% efficacy against H contortus. In trial 2, 30 nematode-free lambs were each given 8,300 F1 generation infective larvae of H contortus, which were derived from parent H contortus that survived 2 levamisole treatments in lambs being maintained in a nematode-free environment. Ten lambs were treated with 8 mg of levamisole/kg as a drench, 10 were treated with 20 mg of netobimin/kg as a drench, and 10 were not treated (control). Nematode recovery after slaughter revealed 62.3% and 99.8% efficacy for levamisole and netobimin, respectively, against H contortus.

Animals↗
PubMed1986

Q fever pneumonia associated with exposure to wild rabbits.

4 patients with atypical pneumonia and a history of exposure to wild rabbits were found to have antibodies to Coxiella burnetii but not to the other organisms also commonly associated with atypical pneumonia. 10 (45%) of 22 snowshoe hares caught in the area where 1 of the patients snared his rabbits had antibodies to Coxiella burnetii. Q fever ought to be included in the differential diagnosis of pneumonia acquired following exposure to wild rabbits.

Animal Population Groups↗
PubMed1986

Primary structure of the reaction center from Rhodopseudomonas sphaeroides.

The reaction center is a pigment-protein complex that mediates the initial photochemical steps of photosynthesis. The amino-terminal sequences of the L, M, and H subunits and the nucleotide and derived amino acid sequences of the L and M structural genes from Rhodopseudomonas sphaeroides have previously been determined. We report here the sequence of the H subunit, completing the primary structure determination of the reaction center from R. sphaeroides. The nucleotide sequence of the gene encoding the H subunit was determined by the dideoxy method after subcloning fragments into single-stranded M13 phage vectors. This information was used to derive the amino acid sequence of the corresponding polypeptide. The termini of the primary structure of the H subunit were established by means of the amino and carboxy terminal sequences of the polypeptide. The data showed that the H subunit is composed of 260 residues, corresponding to a molecular weight of 28,003. A molecular weight of 100,858 for the reaction center was calculated from the primary structures of the subunits and the cofactors. Examination of the genes encoding the reaction center shows that the codon usage is strongly biased towards codons ending in G and C. Hydropathy analysis of the H subunit sequence reveals one stretch of hydrophobic residues near the amino terminus; the L and M subunits contain five such stretches. From a comparison of the sequences of homologous proteins found in bacterial reaction centers and photosystem II of plants, an evolutionary tree was constructed. The analysis of evolutionary relationships showed that the L and M subunits of reaction centers and the D1 and D2 proteins of photosystem II are descended from a common ancestor, and that the rate of change in these proteins was much higher in the first billion years after the divergence of the reaction center and photosystem II than in the subsequent billion years represented by the divergence of the species containing these proteins.

Amino Acid Sequence↗
PubMed1986

Pharmacology of aerosol leukotriene C4- and D4-induced alteration of pulmonary mechanics in anesthetized cynomolgus monkeys.

Aerosol administration of solutions of 900 micrograms/ml of leukotriene C4 (LT) or D4 to cynomolgus monkeys produced dose-dependent, equipotent increases in pulmonary resistance (Rp) and decreases in dynamic lung compliance (Cdyn). Time to peak response was, in part, related to dose and ranged from 4 to 20 min. Both LTC4 and LTD4 were less potent than histamine. Aerosol pretreatment with the cyclooxygenase inhibitor indomethacin had no significant effect on either LTC4 or LTD4 dose-response curves; however, at the highest doses of these agonists a notable, nonsignificant inhibition of effects on both Rp and Cdyn was seen. Intravenous dl-propranolol had no effect on responses to LTD4. Aerosol pretreatment with FPL 55712 significantly (P less than 0.05) inhibited airway responses to both LTC4 and D4. In contrast, an intravenous infusion of FPL 55712 failed to block the bronchospastic activity of LTD4. In conclusion, cynomolgus monkeys are responsive to aerosol administration of LTC4 and LTD4, and the pharmacology of their responses appears to resemble that of man.

Aerosols↗
PubMed1986

Immunosuppression of lymphocyte blastogenesis in cattle infected with Ostertagia ostertagi and/or Trichostrongylus axei.

Twenty 4-month-old calves were infected with O ostertagi and/or T axei and the responses to phytolectins were evaluated. Whole blood cultures were incubated with phytohemagglutinin (PHA), concanavalin A (Con A) and pokeweed mitogen (PWM). The blastogenic response was determined by tritiated thymidine uptake with results presented as counts per minute (cpm), stimulation indices (SI) and a mononuclear cell responsive index determined by dividing the phytomitogen induced cpm by the absolute mononuclear cell number per ul. The control group results were adjusted to 100 percent and changes in the percentage difference by the parasitized calves was determined. There was a decline in lymphocyte responsiveness to PHA beginning at the time of infection. Significant depression of responses to PHA was observed in all parasitized calves 8 weeks after infection although clinical signs of parasitism did not occur. Lymphocyte responses to PW, were not different in infected calves from the control, although the O ostertagi group had significantly higher PWM mean upon than the calves infected with T. axei. A slight depression in response to Con A was also observed at 8 weeks after infection followed by a significant increase after 10 weeks. The immunosuppression appeared to be a feature of gastrointestinal parasitism and related to infections with O. ostertagi and/or T. axei.

Age Factors↗
PubMed1986

Genetic heterogeneity among isolates of Coxiella burnetii.

Chromosomal and plasmid DNA have been extracted from six isolates of Coxiella burnetii, the aetiological agent of Q fever. Restriction fragment length polymorphisms detected after HaeIII digestions of chromosomal DNA revealed four different patterns that distinguished the American from the European isolates, and the Nine Mile phase I prototype strain from a spontaneously derived, isogenic phase II nonrevertant variant. At least one of the HaeIII fragments visible in the pattern from Nine Mile phase I and not in that from Nine Mile phase II could not be detected by DNA-DNA hybridization, and thus may have been deleted during the phase transition. Comparison of Nine Mile phase II, which does not survive animal passage, with Grita M44 phase II, which does, indicated that the HaeIII fragment was present in the Grita strain. These results suggest that this HaeIII fragment may be concerned with functions necessary to survive the cellular immune response in vivo. Isolates from two human endocarditis cases showed the greatest divergence from all the other isolates, having at least five fragments of unique mobility in the HaeIII digestion pattern of their chromosomal DNA. Also, a plasmid obtained from these two isolates was 2 to 3 kb larger than the plasmid present in the other five isolates, and its restriction pattern could be distinguished from that of the other plasmids by several endonucleases. Detection of chromosomal and plasmid restriction fragment length polymorphisms among strains of phase I or phase II C. burnetii from various geographical locations and environmental sources will facilitate Q fever diagnosis and strain identification.

Autoradiography↗
PubMed1986

Overlapping deletion in two spontaneous phase variants of Coxiella burnetii.

Chromosomal DNA from the Nine Mile phase I strain of Coxiella burnetii (CB9MIC7) was cloned into the cosmid vector pHC79. The resulting gene library was probed with a radiolabelled HaeIII fragment present in the parental strain but absent from a spontaneously derived Nine Mile phase II strain (CB9MIIC4). The insert, which includes the missing HaeIII fragment, was 38.5 kb in length. When DNA from this cosmid clone was hybridized to genomic DNA of the parental CB9MIC7 and its derivative CB9MIIC4, a number of fragments were missing or altered in the latter strain. Restriction mapping localized the fragments to a contiguous portion of the chromosomal DNA fragment. The data were consistent with an 18 kb deletion in the chromosome of CB9MIIC4. Another intrastrain spontaneous derivative, CB9MI514, also lacked the sentinel HaeIII fragment and carried a deletion of approximately 29 kb within the same cloned insert. Both deletions appeared to share a common terminus, within the limits of resolution. In all other strains investigated, both phase I and phase II, the DNA represented by the insert seemed intact. The strains examined were representative of various stages of phase variation. The relationship between the observed deletions and the mechanism of phase transition in Nine Mile strains is discussed.

Chromosome Deletion↗
PubMed1986

Characterization of a phase I Coxiella burnetii chloroform-methanol residue vaccine that induces active immunity against Q fever in C57BL/10 ScN mice.

The effect of phase I Coxiella burnetii chloroform-methanol residue vaccine (CMRV) on the response of murine splenic lymphocytes to mitogenic and antigenic stimuli was evaluated in C57BL/10 ScN endotoxinnonresponder mice with an in vitro lymphocyte proliferation assay. Intraperitoneal injection of phase I CMRV resulted in antibody production against phases I and II antigens. Lymphocytes were responsive in vitro to concanavalin A, phytohemagglutinin, pokeweed mitogen, and specific recall antigens. Antibodies against phases I and II antigens were not detected after intraperitoneal injection of chloroform-methanol extract (CME). Lymphocytes also were only slightly hyporesponsive to mitogens. Reconstitution of the CMRV with the CME of phase I whole cells restored the immunopathological reactions that were associated with the phase I whole cell vaccine (WCV). The CMRV was more mitogenic than the WCV for lymphocytes from mice injected with saline. Lymphocytes from phase I WCV-injected mice were negatively modulated with nontoxic concentrations of homologous WCV or CMRV. Lymphocytes from phase I CMRV-injected mice were only slightly hyporesponsive to mitogens and were significantly stimulated by antigens of either WCV or CMRV as recall antigens. Vaccination of mice with 100 micrograms of CMRV, CME, or WCV provided 80, 0, or 50% protection, respectively, against a lethal intraperitoneal challenge with viable phase I C. burnetii. The epitopes which induce immunological hyporesponsiveness, negative modulation, and the death of lymphocytes were fractionated into the CMRV and CME. The CMRV provides at least one of the determinants which induce immunosuppression, whereas CME contains specific or nonspecific components or both. Collectively, these results show that the CMRV may be a potential candidate to replace the WCV currently used for human vaccination.

Animals↗
PubMed1986

Humoral immune response to Rocky Mountain spotted fever in experimentally infected guinea pigs: immunoprecipitation of lactoperoxidase 125I-labeled proteins and detection of soluble antigens of Rickettsia rickettsii.

Rickettsia rickettsii, the etiologic agent of Rocky Mountain spotted fever, purified from infected L-929 cells by density gradient banding were extrinsically radioiodinated with lactoperoxidase. Immunodominant 125I-labeled antigens were identified by radioimmunoprecipitation of detergent-solubilized antigens with protein A-Sepharose and anti-R. rickettsii sera collected 0, 3, 7, 11, 32, and 163 days after infection of guinea pigs. The average fever greater than or equal to 40 degrees C was detected by days 3 and 4 after infection with 6 X 10(7) and 6 X 10(6) PFU, respectively. By microagglutination and complement fixation assays, anti-R. rickettsii antibodies were detected as early as day 3 after infection, with titers increasing markedly between days 7 and 163. Convalescent sera, collected on day 163, from infected guinea pigs were used to identify seven 125I-labeled antigens with apparent molecular sizes of 186,000 (I), 145,000 (II), 49,000 (III), 32,000 (IV), 27,500 (V), 17,500 (VI), and 16,500 (VII) daltons. Differences in antibody reactivity and specificity against the seven antigens were demonstrated with serially obtained sera. Sera from a guinea pig infected with 6 X 10(7) PFU exhibited antibody-antigen interactions with all seven 125I-labeled antigens by day 7, whereas the same antibody activity required 32 days for an animal infected with 6 X 10(6) PFU. Prominent antibody activities toward proteins II and IV were demonstrated both early and late after infection. The fluids obtained from infected L-929 cells contained three soluble antigens which were detected with the 11-, 32-, and 163-day sera by an immunodiffusion assay. The soluble and 125I-labeled antigens of R. rickettsii identified in this study may be important candidates for vaccines against Rocky Mountain spotted fever.

Animals↗
PubMed1986

Identification of phase-specific antigenic fractions of Coxiella burnetti by enzyme-linked immunosorbent assay.

Antigenic fractions of Coxiella burnetii phase variants were identified with an enzyme-linked immunosorbent assay (ELISA). Immune sera from guinea pigs immunized with Formalin-inactivated phase I or phase II whole cells were used to measure the antigenic activity of whole cells and various soluble and particulate preparations. Phase-specific antigens of C. burnetii whole cells and fractions were compared by dose-response curves at different (antigen and antibody) dilutions. Water-soluble extracts prepared by meta-periodate, ether, and phenol extraction of phase I whole cells yielded antigenic fractions which reacted with anti-phase I antibodies. The extraction of phase I whole cells with dimethyl sulfoxide, trichloracetic acid, and Formalin yielded antigenic fractions which detected antibodies in both anti-phase I and -phase II sera. Interestingly, the trichloracetic acid extract of phase I whole cells also contained a component which bound nonimmune immunoglobulin. The sera of animals immunized with whole cells of the phase II Australian QD strain reacted with lipopolysaccharides of the phase I and phase II Nine Mile strains. Therefore, variations in lipopolysaccharide structure among phase variants of C. burnetii were detected as cross-reactions with immune sera from an interspecific strain. Comparisons of immunofluorescence, microagglutination, and the complement fixation assays with the ELISA indicated greater sensitivity and specificity of the ELISA for the measurement of phase-specific antigens and antibodies.

Animals↗
PubMed1986

Humoral immune response to Q fever: enzyme-linked immunosorbent assay antibody response to Coxiella burnetii in experimentally infected guinea pigs.

The response of guinea pigs experimentally infected with Coxiella burnetii organisms, the etiologic agents of Q fever, was obtained by the measurement of fever, circulating infectious C. burnetii cells, and anti-C. burnetii antibodies. The detection of antibodies by the enzyme-linked immunosorbent assay (ELISA) and traditional methods against phase I whole cells, phase II whole cells, and phase I lipopolysaccharide (LPS-I) (a virulence marker for phase I cells) antigens in the serum samples of infected animals revealed marked differences between intrastrain phase variants. Animals infected with the phase I Nine Mile strain produced a concomitant increase in temperature, circulating infectious C. burnetii cells, and antibodies against phase II cells, phase I cells, and LPS-I. At 15 weeks, a challenge of phase I-infected animals with viable phase I cells resulted in anamnestic antibody responses to phase I cells and LPS-I but not to phase II cells. Infection of animals with the phase II Nine Mile strain produced antibodies against only phase II cells. The challenge of phase II-infected animals at 15 weeks with viable phase II cells resulted in anamnestic antibody responses to phase I and phase II cells but not to LPS-I. Suppression of anti-phase II responses by the phase I challenge was apparent with only the ELISA, because the immunofluorescence, microagglutination, and complement fixation assays were insensitive to these changes. The sensitivity and specificity of the ELISA with whole-cell and the LPS-I antigens in the detection of phase-specific antibody revealed that avirulent phase II cells induced an immune response to phase I antigenic epitopes. Although the avirulent phase II cells were rapidly cleared by the host immune responses, they were sufficiently infective to induce antibody responses to both phase variants. Thus, in the occurrence of Q fever, any conventional serological technique that uses only phase II antigens may not provide a true incidence of naturally acquired infection with both phase I and II C. burnetii organisms.

Agglutination Tests↗
PubMed1986

Transport of solute in proximal tubules is modified by changes in medium osmolality.

To examine the hypothesis that fluid absorption is driven by transepithelial osmotic differences, we measured such differences in proximal tubules perfused under oil and attempted to increase the rate of fluid absorption (Jv) and hence the absorbate-perfusate osmotic differences by lowering the osmolality of the perfusate. We were able to consistently increase Jv in this manner only in proximal straight tubules perfused with a simple perfusate that contained no bicarbonate or amino acids. With the simple perfusate, a small but significant increase in the absorbate-perfusate osmolality difference was seen with increased Jv, which is expected if the volume absorption is driven by a transepithelial osmotic difference. In addition, lowering the perfusate osmolality from 290 to 160 mosmol/kg H2O increased the rate of solute absorption from 79 +/- 7 to 91 +/- 8 posmol . min-1 . mm-1; this increase was partly accounted for by an increase in the rate of absorption of glucose from 6.6 +/- 0.9 to 9.5 +/- 1.1 pmol . min-1 . mm-1. In contrast, with the complete perfusate in proximal straight tubules there was little or no increment in Jv, no change in transepithelial osmolality differences, and a decrease in the rate of solute transport with hypoosmolality from 136 +/- 21 to 87 +/- 22 posmol . min-1 . mm-1. In proximal convoluted tubules, similar results were obtained, but a time-dependent decline of Jv complicated the interpretation of the results in the convoluted tubules. It is hypothesized that the observed changes in solute transport with hypotonic perfusate may be the result of changes in membrane permeability that are subsequent to cell swelling.

Animals↗