Biomedical subjects
Publications and source records attributed to R Higgins.
Primary aortic tumors are rare, difficult to diagnose, and often fatal. This case and a review of the literature identified aortic tumors as a potential source of emboli leading to acute mesenteric insufficiency. The case showed the efficacy of magnetic resonance imaging in diagnosing and determining the extent and location of an aortic tumor.
A study was conducted to evaluate the possibility of using biochemical differences among strains of a given serotype of Actinobacillus pleuropneumoniae as epidemiological markers, to rapidly identify the source of infection in herds affected with swine pleuropneumonia. Out of 38 different biochemical and physiological tests performed on a total of 67 strains belonging to serotypes 1 and 5 of A. pleuropneumoniae, three fermentation tests, glycerol, lactose and raffinose, allowed the classification of serotype 1 strains into 6 phenotypic groups and serotype 5 strains into 4 of these groups. Groups II and III were exclusively composed of serotype 1 strains, whereas the majority of strains in groups I and IV belonged to serotypes 1 and 5 respectively, the latter comprising almost all the serotype 5 studied.
Sixty-two isolates of Campylobacter cryaerophila were recovered from aborted porcine and bovine fetuses, from porcine, bovine, and equine feces, and from different tissues of a dead piglet. Phenotypic characterization was carried out on all isolates, and the results were compared with those obtained with the reference strains of C. cryaerophila, C. jejuni, C. coli, C. laridis, and C. hyointestinalis. The ability of C. cryaerophila strains to grow under aerobic conditions at 16 degrees C was found to be most useful in differentiating them from strains of other Campylobacter species. Studies were undertaken to develop a serotyping system for C. cryaerophila on the basis of the Lior serotyping system for C. jejuni and C. coli by use of a tube agglutination test with formalinized whole-cell (FWC) and boiled whole-cell (BWC) antigens. Antisera against 18 strains of C. cryaerophila were produced in rabbits. Thirty-five percent of C. cryaerophila strains were typed with the FWC suspension as an antigen, and 61% were typed with the BWC suspension as an antigen. None of the C. cryaerophila strains tested autoagglutinated in saline. BWC antigens of C. jejuni, C. coli, and C. laridis cross-reacted with C. cryaerophila, whereas FWC antigens did not cross-react. Neither FWC nor BWC antigens of C. hyointestinalis reacted with C. cryaerophila antisera.
Six new capsular types of Streptococcus suis (types 23 to 28) are described. All reference strains were isolated from diseased pigs and were morphologically and biochemically similar to previously described capsular types 1 to 22. Clear and specific reactions were obtained for each of the new capsular types with three different typing techniques; no cross-reactions were detected among them or with other S. suis capsular types. Their capsular material presented similar ultrastructural characteristics, as shown by electron microscopy, and fimbriae similar to those described for other capsular types of S. suis were observed. When untypeable field isolates were tested with antisera raised against the six new capsular types, capsular type 23 appeared to be the most prevalent, representing more than 50% of all these isolates. Most isolates were recovered from cases of pneumonia, septicemia, and meningitis. Presumptive biochemical identification described for S. suis capsular types 1 to 22 may also be used for capsular types 23 to 28.
The incidence and biochemical patterns of Streptococcus suis capsular types 9-22 are presented. Of 148 untypeable (with types 1-8 antisera) isolates of S. suis recovered from diseased pigs, 10% were not capsulated. Of the remaining 134 isolates, only 53% belonged to capsular types 9-22; capsular types 22 and 9 were the most prevalent, representing 19% and 13%, respectively. Capsular type 15 (de Moor's group T Streptococcus) is reported here for the first time in North America since it was described in 1963 in Europe. Of 188 untypeable isolates recovered from clinically healthy pigs, 25% were noncapsulated. Of the remaining 141 isolates, 90% belonged to the new capsular types, and 87% were identified as 1 of 4 types: 17, 18, 19, and 21. Capsular types 12 and 20 were not detected among the Canadian isolates. Almost half of strains were arginine dihydrolase-negative, and 45% fermented mannitol, which is seldom a positive test with capsular types 1-8. Although some strains were negative with salicin or trehalose, none were negative for both sugars. Only 54% of isolates tested with 1 rapid multitest system were correctly identified as S. suis. A tentative biochemical profile that might be used with a microplate identification system is also presented. Biochemical identification using the conventional system instead of the rapid multitest system is preferable.
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Twenty-nine field isolates of porcine Pasteurella multocida were characterized for their capsular and somatic types and were evaluated for their susceptibility to 10 antimicrobial agents. Plasmid DNA-screening experiments were conducted to determine whether a relationship existed between the presence of plasmids and antibiotic resistance. Field isolates of P multocida were susceptible to most of the antimicrobials tested, but all isolates were resistant to clindamycin. Eleven isolates of serogroup D were resistant to 1 or 2 antimicrobial agents. Resistance to sulfonamides and streptomycin was observed in 7 isolates. These isolates contained R plasmids conferring resistance to streptomycin and sulfonamides. The R plasmids belonged to 2 groups, one of 5.6 kilobase and the other of 5.9 kilobase. Restriction endonuclease mapping and DNA hybridization revealed that these R plasmids were related to RSF1010 from Salmonella panama, which also confers resistance to streptomycin and sulfonamides.
A biotin/avidin double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) for the detection of antigens of Leptospira interrogans serovars in experimentally inoculated bovine urine samples was evaluated. Immunoglobulin G (IgG) from rabbits immunized with L. interrogans serovar hardjo type hardjobovis sonicated, whole cell, and formalinized-heated antigen preparations were purified by a protein A-superose column coupled to fast protein liquid chromatography, and evaluated for species specificity in the ELISA. The ELISA using each specific IgG detected as few as 10(4) leptospires of the homologous serovar hardjo diluted in phosphate-buffered saline solution with Tween 20 (PBSS-Tween 20). On immunoblot analysis of proteinase-K-digested whole cell leptospiral preparations, each IgG revealed the presence of bands specific to serovar hardjo, suggesting the presence of serovar-specific epitopes on the lipopolysaccharide molecules. The minimum number of cells of heterologous serovars pomona, grippotyphosa, bratislava, icterohaemorrhagiae and copenhageni detected by each ELISA was greater, ranging from 10(6) to 10(7). The common antigenic determinants observed on immunoblot analysis were different for each specific IgG, except for a major cross-reacting, possibly flagellar, protein doublet at approximately 36-36.5 kDa. Leptospires were equally well detected by the ELISA in both bovine urine and PBSS-Tween 20.
The present study was undertaken to evaluate the ability of 33 Streptococcus suis capsular type 2 isolates to adhere to frozen sections of porcine lung. Twenty isolates originated from diseased pigs and 13 from the nasal cavities of clinically healthy pigs. All isolates from diseased animals adhered to lung sections; isolates from pneumonia adhered, in general, in greater numbers than isolates from meningitis. Only four isolates from clinically healthy animals showed a weak adherence to lung sections. Hydrophobic surface properties were also evaluated. All isolates tested appeared to possess a hydrophilic cell surface. The thickness of the capsular material correlated well with the degree of adherence. However, when the adherence capacity of a noncapsulated mutant was compared with that of the parent strain, it was found that the mutant strain had at least the same adherence capacity as the capsulated parent strain. The data suggest that S. suis capsular type 2 isolates involved in pathological conditions can adhere to porcine lung tissue. The adherence activity does not seem to involve hydrophobic interactions. The amount of capsular material seems to influence the adherence activity, but is probably not the only mechanism involved.
Seroprevalence of Actinobacillus (Haemophilus) pleuropneumoniae serotype-1 infection was evaluated in pigs on 7 farms in Quebec. Commercial cross-bred herds A to G, ranging from 110 to 235 sows and infected with A pleuropneumoniae serotype-1 were selected. Five pigs/litter were selected at random and were identified (group 1). Blood samples were obtained from group-1 pigs at 2 to 4, 14, 28, 42, and 56 days of age. Blood also was obtained from group-1 pigs remaining in the postweaning unit at 70 days of age, and from 20 to 40 sows 1 to 3 times. To determine prevalence of seropositive pigs in all age groups for the entire study period in herds C to G, blood samples were obtained from 20 pigs/age group (group 2) selected at random at 28, 42, and 56 days of age at each visit. Group-1 pigs were included when they reached 28, 42, and 56 days of age. Pigs were serologically monitored in herds A and B for 3 months and in herds C to G for 5 to 6 months. Serologic status of pigs at 2 to 4 days of age was not statistically associated with status at 42 days (P = 0.6293) and at 56 days (P = 0.3098) of age for the same pigs. Therefore, seronegative pigs 2 to 4 days old did not seroconvert earlier than did those with detectable maternal antibodies at 2 to 4 days old. Only about 50% of the 70-day-old pigs were seropositive at 56 days. Seemingly, pigs seroconverted late in the postweaning period.(ABSTRACT TRUNCATED AT 250 WORDS)
Transgenic tobacco plants and progeny carrying coding sequences for neomycin phosphotransferase II (NPTII) and beta-glucuronidase (GUS) were recovered following microprojectile bombardment of tobacco leaves. Transgenic plants were regenerated from bombarded leaf pieces of tobacco cvs. 'Xanthi' and 'Ky 17' which were cultured in the presence of 100 or 200 micrograms/ml kanamycin for six to eight weeks. Among 160 putative transgenic plants from at least 16 independent transformation events 76% expressed NPTII, and 50% expressed GUS. Southern analysis of plants expressing either one or both of the enzymes indicated DNA in high molecular weight DNA in 8 of 9 independent transformants analyzed. Two independent transformants and their progeny were analyzed in detail. Analysis of progeny for quantitative enzyme levels of NPTII and GUS, and Southern analysis of parents and progeny clearly demonstrated that the genes were transmitted to progeny. One transformant demonstrated Mendelian ratios for seed germination on kanamycin-containing medium while the other transformant had non-Mendelian ratios. DNA analysis of progeny indicate complex integration of the plasmid DNA, and suggest that rearrangements of this DNA has occurred. These results are consistent with other methods of direct DNA uptake into cells, and verify that the microprojectile bombardment method is capable of DNA delivery into intact plant cells which can give rise to transgenic plants and progeny.
The presence of capsular material on cells of nine reference strains of Streptococcus suis representing serotypes 1 to 8 and 1/2 was determined by transmission electron microscopy after polycationic ferritin labeling, immunostabilization, or fixation with a combination of glutaraldehyde and lysine. All the cells of the reference strains examined were covered with a layer of capsular material whose thickness varied between 20 to 30 nm and 350 to 375 nm when examined by immunostabilization. Capsular material from cells exposed to homologous antiserum was usually thicker than that from polycationic ferritin-labeled cells or cells fixed with glutaraldehyde-lysine. Negative staining revealed detectable surface structures on S. suis strains. All strains carried peritichous, thin, and flexible fimbriae with a diameter of approximately 2 nm and a length of up to 250 nm. This study indicated that morphological differences of surface structure exist among S. suis reference strains.
A total of 49 strains (23 reference strains and 26 field isolates) of Streptococcus suis were tested for their ability to agglutinate erythrocytes from different animal species. Ten different hemagglutination patterns were established. Thirty-three strains (67%) did not agglutinate any of the erythrocytes tested; sixteen strains (33%) agglutinated erythrocytes from one or more animal species. Different strains belonging to the same capsular type presented different hemagglutination patterns. No correlation was found between the tissue origin and/or the virulence (evaluated in 4-week-old mice) of different field isolates and their hemagglutination activity. Hydrophobic surface properties were also evaluated. All S. suis strains studied appeared to possess a hydrophilic cell surface. Morphologically similar fimbriae were observed on hemagglutinating as well as on nonhemagglutinating strains of S. suis. This study provides evidence that certain strains of S. suis possess hemagglutinating properties which do not appear to involve hydrophobic interactions. The possible role of fimbriae in hemagglutination remains unclear.
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The minimal inhibitory concentrations of carbadox, dimetridazole, lincomycin, ronidazole, and tiamulin against isolates of Treponema hyodysenteriae and Treponema innocens were determined by an agar-dilution method. The results obtained indicated that tiamulin was the most effective antimicrobial in vitro against T. hyodysenteriae, followed by carbadox. Dimetridazole, lincomycin, and ronidazole had poor efficacy in vitro against the T. hyodysenteriae isolates. Isolates of T. innocens were more sensitive to the various antimicrobials. Carbadox and tiamulin were the most effective in vitro, followed by ronidazole, dimetridazole, and lincomycin.
252Cf neutron brachytherapy was tested in a feasibility trial for efficacy for cervix cancer therapy vs. high stage radioresistant and subsequently for all stages of disease. Actuarial survival curves were analyzed for 218 patients treated between 1976 and 1983 and followed five to 14 years to the present time. A variety of doses, schedules and methods for brachytherapy was tested during this period, and a dose-response relationship for tumor eradication studied. All treatments were combined with whole-pelvis photon radiotherapy to approximately 45 to 60 Gy. This combination was found effective, particularly if an early implant schedule was used for the Cf implant, followed by whole-pelvis photon radiotherapy. For bulky/barrel shaped low-stage disease in medically fit patients, 252Cf implants were combined with surgery, i.e., extrafascial hysterectomy and was readily usable for treatment without complications and with high cure rates (92% five-year survival). All survivals and outcomes to 13 years match the best results of conventional photon radiotherapy. For all stages better results were observed for bulky, barrel, and advanced-stage tumors, especially for local tumor control, if optimal schedules, doses and implant numbers were used. Knowledge about neutron dose, dose per implant, number of implants and combination with photon beam therapy evolved during the trials. 252Cf represents a new quick acting effective radioisotope for human cancer therapy especially for treatment of radioresistant, bulky and high stage cancers.