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Biomedical subjects

J R Saunders

Publications and source records attributed to J R Saunders.

At least 127 records · Page 7Linked to original sources
PubMed1983

Surgical management of small-bowel radiation enteritis.

We treated 17 patients with severe small-bowel radiation enteritis surgically. Fourteen patients were female. Gynecologic malignant lesions (cervical, ovarian, and endometrial) were the most frequent sites of the primary tumors for which radiation was given. Thirteen patients had bowel obstruction, and the remainder had enterovaginal fistulae. Intestinal bypass, rather than resection, was the preferred approach in the treatment of these patients, and was used in 11 cases. Successful palliation was provided in nine patients, with minimal morbidity and no operative deaths. Follow-up at eight to 60 months has shown no further sequelae of radiation injury or of blind loop syndrome. This supports the relative safety of intestinal bypass for the surgical management of small-bowel radiation enteritis.

Adult↗
PubMed1983

Value of contralateral supraomohyoid neck dissections.

This study was carried out to determine the merit of contralateral supraomohyoid neck dissection in the clinically negative neck. When performed in conjunction with a standard radical neck dissection on the ipsilateral side, a yield of 2.8 percent pathologically positive nodes (5 of 177) was obtained in the contralateral neck. Little difference was noted in the yield of midline lesions versus unilateral lesions which approached the midline (3 and 2.6 percent, respectively). Similarly, the yield with preoperative radiation was close to that of the nonradiated group (3 and 2.7 percent, respectively). Additionally, in 1.7 percent of patients (3 of 177) with both clinically and pathologically negative nodes, metastases later developed in the contralateral neck, which indicates that the dissection is not necessarily effective in preventing future disease. The contralateral supraomohyoid neck dissection in the treatment of malignancies of the oral cavity, pharynx, and larynx does not appear to be of significant therapeutic value.

Head and Neck Neoplasms↗
PubMed1983

Dose response relationship of Haemophilus pleuropneumoniae aerosols in pigs.

The virulence of Haemophilus pleuropneumoniae was quantitated for ten and 12 week old pigs following aerosol exposure. The volume and concentration of culture aerosolized, the estimated numbers of organisms inhaled by the pigs and the mortality rates at 72 hours postexposure were computed and used to calculate the LD50. There was correlation between the concentration of culture aerosolized, the amount of the estimated inhaled dose and the mortality rates. The ten week old pigs were apparently more susceptible to aerosols of H. pleuropneumoniae than the 12 week old pigs. The LD50 value or a multiple of it appears to be a reasonable basis for a standardized aerosol challenge of the immunity of pigs vaccinated with experimental or commercial H. pleuropneumoniae vaccines.

Aerosols↗
PubMed1983

Pulmonary clearance of Bacillus subtilis spores in pigs.

The pulmonary clearance rate of Bacillus subtilis was determined in ten pigs (23-39 kg) exposed simultaneously for 15 minutes to an aerosol generated by an ultrasonic nebulizer. Two pigs were killed at each interval of zero, two, four, eight and 12 hours and the concentrations of B. subtilis in lungs (all lobes), dorsal and ventral nasal turbinates, trachea, pharyngeal and bronchial lymph nodes were determined. The mean percent (+/- standard error) pulmonary clearance of B.subtilis was 54.2+/-11.7, 53.0+/-11.8, 77.4+/-5.2 and 88.1+/-3.7 at two, four, eight and 12 hours, respectively. The numbers of B. subtilis retained in the posterior (caudal and accessory) lobes at zero time were significantly greater than those in the anterior (cranial and middle) lobes (P<0.05). However, by 12 hours postinoculation the numbers of organisms retained in the two regions did not differ significantly (P>0.05). The mean percentage of B. subtilis retained by the turbinates, trachea, pharyngeal and bronchial lymph nodes varied between pigs at each time interval, but was usually less than that retained by the lungs. It was concluded that deposition of B. subtilis spores took place in all parts of the respiratory tract when pigs were exposed to aerosols and that the spores were progressively cleared by the normal lung.

Aerosols↗
PubMed1983

A model aerosol exposure system for induction of porcine Haemophilus pleuropneumonia.

One group of six pigs and another group of three pigs were separately exposed in a polyethylene enclosed chamber for ten minutes, respectively, to Haemophilus pleuropneumoniae serotype 1 and Bacillus subtilis aerosols generated by an ultrasonic nebulizer. Haemophilus pleuropneumoniae and B. subtilis were deposited throughout the lungs immediately following aerosol exposure. The number of H. pleuropneumoniae and B. subtilis deposited varied within and between lungs in each group. The mean numbers of both organisms deposited in the posterior (caudal and accessory) lobes were significantly greater than those in the anterior (cranial and middle) lobes (P less than 0.001). The four principals that received H. pleuropneumoniae aerosols and the two contact controls developed fatal fibrinous pneumonia which simulated that seen in natural infections. Since this exposure system consistently resulted in clinical disease it has good potential as a model for the study of pathogenesis of the disease and more specifically for the evaluation of vaccines.

Aerosols↗
PubMed1982

Pulmonary clearance of Haemophilus pleuropneumoniae and Serratia marcescens in mice.

Bacterial counts (per lung) were made from Swiss White and/or C3H mice, inoculated intranasally with either Haemophilus pleuropneumoniae or Serratia marcescens and killed at specific times. The percentages of bacterial survival and clearance at each time were determined. Serratia marcescens was cleared progressively, but not completely, from the lungs of C3H and Swiss White mice. The overall pulmonary clearance of S marcescens by Swiss White mice was significantly greater than that of C3H mice (P less than 0.01). The pulmonary clearance pattern of H pleuropneumoniae in C3H mice differed according to the dose inoculated. With a larger H pleuropneumoniae median lethal dose (0.1 LD50), the organism multiplied consistently up to 25 times by 12 hours after the inoculations were done, when clinical signs and lesions appeared in a few of the mice. The clearance rates at 24 and 48 hours after inoculations were 60.65% and 10.3%, respectively. Mice given 0.04 LD50 H pleuropneumoniae showed a 10-fold increase of H pleuropneumoniae in the first 4 hours, with clearances reaching 33%, 66%, and 99% at 8, 12, and 24 hours, respectively.

Animals↗
PubMed1982

Studies on immunity to Haemophilus pleuropneumoniae infections in mice.

A murine model of experimentally induced Haemophilus pleuropneumoniae respiratory tract infections was developed and used to evaluate the efficacy of bacterins. Various doses of 3 H pleuropneumoniae strains (serotype 1 and 5) were administered intranasally (IN) to groups of anesthetized Swiss White mice. The accumulated mortality per group at 5 days after they were inoculated was used to calculate the median lethal dose (LD50), which ranged between 1.4 x 10(6) and 5.4 x 10(7) bacteria. There was correlation between dose administered, incubation period of the disease, and mortality. The induction of H pleuropneumoniae disease in the mouse was reproducible and resembled that of naturally occurring porcine Haemophilus pleuropneumonia. The murine model of exposure was used to evaluate the efficacy of H pleuropneumoniae serotype 5 (strain B78-3760) bacterins administered subcutaneously (SC) and IN. Vaccination by SC route induced slightly higher titers of specific seroagglutinins, compared with the response induced by the IN route, and the former was more effective in protecting mice against IN challenge with H pleuropneumoniae. However, vaccination was not efficacious in mice given a challenge dose greater than 1.2 LD50. The percentage survival rates in the SC and IN vaccinated mice were significantly greater than in the control groups at P less than 0.01 and P less than 0.05, respectively.

Animals↗
PubMed1981

Intraspecific and intergeneric mobilization of non-conjugative resistance plasmids by a 24.5 megadalton conjugative plasmid of Neisseria gonorrhoeae.

pLE2451, a 24.5 megadalton conjugative plasmid from Neisseria gonorrhoeae, was capable of efficiently mobilizing gonococcal beta-lactamase plasmids between gonococci and from gonococci to Haemophilus influenzae and restriction-deficient Escherichia coli. Donor strains of N. gonorrhoeae carrying pLE2451 were also found to be capable of mobilizing a variety of non-conjugative plasmids originally derived from enteric bacteria or Haemophilus species when such plasmids were resident in E. coli. Nevertheless, pLE2451 was not detected physically in E. coli or H. influenzae transconjugants. This suggests that the plasmid is unstable in these hosts but survives transiently to provide transfer functions for mobilization. The proficiency of pLE2451 in promoting intraspecific and intergeneric mobilization was not paralleled by pUB701, pRI234 and pFR16017, a series of conjugative plasmids derived originally from Haemophilus species. These plasmids were incapable of mobilizing even Haemophilus beta-lactamase plasmids, such as RSF0885, between Haemophilus species.

Conjugation, Genetic↗
PubMed1981

Transformation of Escherichia coli with plasmid deoxyribonucleic acid: calcium-induced binding of deoxyribonucleic acid to whole cells and to isolated membrane fractions.

Plasmid deoxyribonucleic acid (DNA) was tightly bound to cells of Escherichia coli at 0 degrees C in the presence of divalent cations. During incubation at 42 degrees C, 0.1 to 1% of this DNA became resistant to deoxyribonuclease. Deoxyribonuclease-resistant DNA binding and the ability to produce transformants became saturated when transformation mixtures contained 1 to 2 micrograms of plasmid NTP16 DNA and about 5 X 10(8) viable cells. Under optimum conditions, between 1 and 2 molecule equivalents of 3H-labeled NTP16 DNA per viable cell became deoxyribonuclease resistant. Despite this, only 0.1 to 1% of viable cells became transformed by saturating amounts of the plasmid. The results suggest that transport of DNA across the inner membrane is a limiting step in transformation. After transformation the bulk of labeled plasmid DNA remained associated with outer membranes. However, in vitro assays indicated that plasmid DNA would bind equally well to preparations of inner or outer membranes provided divalent cations were present to preparations of inner or outer membranes provided divalent cations were present. Divalent cations promoted differing levels of binding to isolated inner and outer membranes in the order Ca2+ much greater than Ba2+ greater than Sr2+ greater than Mg2+. This parallels their relative efficiencies in promoting transformation. Binding of plasmid DNA was greatly reduced when outer membranes were treated with trypsin; this suggests that protein components may be required for the binding or transport of DNA (or both) during transformation.

Biological Transport↗
PubMed1981

An abattoir survey of the incidence of pneumonia in Saskatchewan swine and an investigation of the microbiology of affected lungs.

The lungs of 15 409 pigs, mostly from Saskatchewan, slaughtered at an abattoir were examined over a one year period. The incidence of lesions was 36.7% for "enzootic" pneumonia and 2.1% for pleurisy unassociated with pneumonia. Seasonal variations were recorded and compared with the results of similar surveys carried out in Australia, Belgium and England. Mycoplasmological examination of lungs from 347 animals was consistently negative for Mycoplasma hyopneumoniae. Pasteurella multocida was the commonest bacterial isolate, a result which agrees with those of other workers.

Animals↗
PubMed1981

Pneumonia in Saskatchewan swine: abattoir incidence of intrathoracic lesions in pigs from a herd infected with Haemophilus pleuropneumoniae and from other herds.

A 1978-79 survey of the incidence of thoracic cavity lesions at slaughter had shown that the overall incidence of pleurisy in Saskatchewan swine was low (2%). Therefore, in the summer of 1979 a comparison was made between the incidence of pleurisy in a herd of pigs chronically affected with Haemophilus pleuropneumoniae pneumonia and in animals from other herds slaughtered at the same time. The incidence of pleurisy in control pigs (3.6%) was slightly higher than in the large scale survey but in the pigs from the Haemophilus infected herd it was almost four times as great (13.3%). In the same herd the survivors of a batch of pigs which had been decimated by more severe disease showed an incidence of 32% pleurisy. The economic implications of these findings are detailed and discussed.

Animals↗
PubMed1980

Haemophilus somnus infections I. A ten year (1969-1978) retrospective study of losses in cattle herds in Western Canada.

A total of 838 outbreaks of fatal Haemophilus somnus infections in herds of cattle were diagnosed at provincial veterinary laboratories in Manitoba, Saskatchewan, Alberta and British Columbia during the period 1969-1978. The index cases from these outbreaks included 759 cases of thromboembolic meningoencephalitis, 78 cases of fibrinous pneumonia with pleuritis and one case of H. somnus abortion. The epizootics were subdivided on the basis of province, class and age of cattle and seasonal occurrence. Most outbreaks occurred in a feedlot-type of operation, approximately four weeks after arrival of the cattle. There was often a history of respiratory disease prior to an outbreak and in some cases thromboembolic meningoencephalitis had occurred in the herd the preceding year. The average morbidity-mortality ratio was 2.7/1. The average economic loss per herd was $3 190 based on an average of 15 sick animals and five deaths per affected herd.

Animals↗
PubMed1980

Haemophilus somnus infections. II. A Canadian field trial of a commercial bacterin: clinical and serological results.

To evaluate the efficacy of a Haemophilus somnus bacterin a total of 1114 beef calves or yearling bulls were used in the province of Saskatchewan. The six herds were included in a vaccination trial in which the vaccine was administered subcutaneously in one or two doses. The prevalence of H. somnus in nasal swabs of these animals at the time of the initial vaccination was 0.35% Postvaccination information on morbidity and mortality for a four month period was requested from the five ranches where there were nonvaccinated control calves. Postvaccination outbreaks of infectious thromboembolic meningoencephalitis occurred in two of these herds and, although the numbers were limited, there was a trend to reduced morbidity and mortality in the vaccinated animals compared to controls. Seroconversion rates, as determined by the complement fixation test, in the six herds were 28.3% for control calves, 57% for animals vaccinated once and 80.3% for animals vaccinated twice. On the basis of these results the bacterin was considered to be sufficiently efficacious to warrant its further evaluation under field conditions.

Animals↗