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Biomedical subjects

A B Richards

Publications and source records attributed to A B Richards.

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

Treatment of rotavirus infection in neonate and weanling pigs using natural human interferon alpha.

Colostrum-deprived neonate piglets challenged with rotavirus and 3-week-old newly weaned piglets naturally exposed to rotavirus were treated with low doses of natural human interferon alpha (nHuIFN alpha) administered into the oral cavity or included in the liquid diet. The colostrum-deprived piglets given the highest dosage of nHuIFN alpha (50 IU/kg body weight) had lower viral excretion scores at 3 (p less than 0.11) and 4 days (p less than 0.001) after virus inoculation. Average group weights and weight gains were consistently greater for all nHuIFN alpha-treated neonate groups; however, these differences were not significant. Mortality rates were lower in neonates for the three highest nHuIFN alpha treatment groups (20%, 30%, and 20%) than in the lowest treatment group and controls (60% and 45%, respectively). Three-week-old weanling piglets did not have significant differences in the total average diarrhea or rotavirus excretion scores. After 10 days, the group receiving the highest dosage of nHuIFN alpha had significantly greater average weight gain than the control group (p less than 0.05). There was a significant (p less than 0.01) dose-dependent effect between the logarithm10 of the nHuIFN alpha dosage and weight gain in weanling piglets. There were no death losses in the 3-week-old weanling piglets from natural rotavirus exposure.

Animals↗
PubMed1990

Comparison of DNA:DNA homology and enzymatic activity between Pasteurella haemolytica and related species.

A commercially available microbiological identification system and DNA:DNA hybridization were used to determine relationships between and within serovars 1-13 of Pasteurella haemolytica, and between P haemolytica and P multocida and 4 species of Actinobacillus. All serovars of P haemolytica that belonged to biovar A were related with mean DNA homology of 78%, whereas all serovars of P haemolytica that belonged to biovar T were related to each other with mean DNA homology of 90%. The DNA:DNA hybridization between strains of biovars A and T ranged from 3 to 13%, indicating little or no genetic relationship between the 2 biovars of P haemolytica. The DNA homology between all serovars of P haemolytica and other species of non-P haemolytica bacteria tested (P multocida and actinobacilli) was less than 14%, suggestive of essentially no genetic relationship of P haemolytica with the ATCC reference strains of the genus Pasteurella or the genus Actinobacillus. Enzymatic differences were observed between P haemolytica and the other non-P haemolytica bacteria tested; however, the microbiological identification system that uses enzymatic reactions could not distinguish among biovars of P haemolytica. Results of this research support other data that suggest that biovars A and T of P haemolytica should be classified as separate species, but do not support the inclusion of either biovar A or T within the genus Actinobacillus.

Acid Phosphatase↗
PubMed1990

Chronic recurrent aphthous stomatitis: oral treatment with low-dose interferon alpha.

Recombinant human interferon alfa-2a (HuIFN alpha) was administered orally once daily in a low concentration (1,200 IU/day) to nine patients with chronic recurrent aphthous stomatitis (RAS), and a placebo solution was given to 10 control chronic RAS patients in a double-blind study. All HuIFN alpha-treated patients had total remission of their aphthae within a 2-week period, while placebo control patients had no change in their condition. The 10 placebo control patients were then treated with HuIFN alpha in a manner identical to that used for the initial principal group. Within a 2-week period, all original placebo patients had complete remission of their aphthae. Eleven of the patients did not have a recurrence of RAS during a subsequent 6-month observation period. Eight patients had recurring aphthae; however, the lesions were resolved by retreating with oral HuIFN alpha for less than 1 week.

Administration, Oral↗
PubMed1990

Chronic major aphthous stomatitis: oral treatment with low-dose alpha-interferon.

Two patients with chronic major aphthous stomatitis of at least 3 years duration were treated with single daily oral doses (1,200 IU) of interferon alfa-2 alpha (HuIFN alpha). Both patients responded with complete remission of aphthae within 6 weeks. One patient had no recurrence of the disease during a 6-month observation period. The second patient had a recurrent aphtha approximately 4 weeks after the initial lesion resolved; however, the recurrent lesion was less severe than the patient had historically experienced. Retreatment of the recurrent lesion with HuIFN alpha resulted in complete remission within 1 week, and there were no further recurrences during the 6-month observational period.

Adult↗
PubMed1989

Functional and metabolic activity of bovine pulmonary lavage cells phagocytically stimulated with pathogenic isolates of Pasteurella haemolytica.

Live Pasteurella haemolytica biotype A, serotype 1 isolates (n = 3) and Escherichia coli K-12, strain W3110, were reacted with bovine pulmonary lavage cell (PLC) suspensions. The comparative effects of the different bacteria on the functional and metabolic activity of alveolar macrophages (AMO) in the PLC suspensions were assessed simultaneously by use of 51Cr release, luminol-dependent chemiluminescence (LDCL), and AMO bactericidal assays. The bovine PLC responded differently to E coli, than to the 3 P haemolytica isolates in each of the 3 experimental test systems; however, responses to each of the P haemolytica isolates were not found to be significantly different. Unopsonized live P haemolytica cells adversely affected the functional and metabolic response of PLC, whereas there was no evidence of a cytotoxic (cytocidal) influence of E coli. A difference in 51Cr release for reaction mixtures containing E coli and P haemolytica was not detected at zero time; however, at each subsequent time, reaction mixtures phagocytically stimulated with P haemolytica had significantly increased amount of 51Cr release (P less than 0.05), compared with those mixtures containing E coli. Bovine AMO in the PLC suspensions were able to effectively kill E coli in vitro, but were unable to prevent survival and subsequent growth of P haemolytica. The luminol-dependent chemiluminescence profiles for reaction mixtures phagocytically stimulated with E coli provided evidence of sustained production of oxygen radicals with antimicrobial capabilities by bovine AMO in the PLC. Production of these highly reactive antimicrobial oxidants appeared initially in cultures containing P haemolytica but, subsequently, their production declined precipitously and ceased altogether.

Animals↗
PubMed1989

Blood bactericidal assay (Pasteurella haemolytica) comparison of morbidity in marketed feeder calves.

An in vitro bactericidal assay that used bovine heparinized blood was investigated for its usefulness in detecting differences in the bactericidal immunity of calves against Pasteurella haemolytica serotype 1 (Ph1). Greater than 90% of killing occurred within 30 minutes. The substitution of fetal calf serum for autologous calf plasma caused loss of bactericidal activity of the blood. Decomplemented calf serum also was low in bactericidal activity. The blood bactericidal assay appears to be opsonin antibody-dependent and complement-dependent. The coefficient of variation (CV) that can be expected with this assay was established by use of a group of 8 calves; within-day CV maximum was 0.9, and between-day CV maximum was 2.1. The blood bactericidal assay was used to evaluate 30 calves under typical market stress from 4 farms in eastern Tennessee. All calves had decreased bactericidal activity, as they moved into a feedyard in Texas. The bactericidal activity was reduced among sick calves, based on the severity of clinical signs. Morbidity was highest during the first 14 days in the feedlot. During this period, healthy calves had a decreased bactericidal index (BI) of 4 points, and calves with clinical signs of bovine respiratory tract disease for 3 days had a decreased BI of 8 points. The average reduction in the BI of calves with clinical signs of bovine respiratory tract disease for 6 or more days was 14 points.

Animals↗
PubMed1986

Bovine pneumonic pasteurellosis: evaluation of interactions between bovine pulmonary lavage cells and Pasteurella haemolytica (biotype A, serotype 1), using a luminol-dependent chemiluminescence assay.

In vitro interactions of bovine pulmonary lavage cells (PLC) and pathogenic isolates of Pasteurella haemolytica biotype A, serotype 1, were examined, using a luminol-dependent chemiluminescence (LDCL) assay. The PLC containing high concentrations of bovine alveolar macrophages were incubated with living and heat-killed P haemolytica at bacteria to PLC ratio of approximately 1:1. Kinetics of the mean LDCL response of bovine PLC to heat-killed P haemolytica cells were characterized by a gradual increase in the amount of light emitted over 150 minutes followed by a slight decrease at 180 minutes. In contrast, the LDCL responses of reaction mixtures containing living P haemolytica were characterized by the development of a maximal response at 60 minutes followed by a continued precipitous decrease in light emission to background values by 150 minutes. Differences were not noticed in the LDCL response of PLC suspensions from the same cow to 3 P haemolytica isolates. In each instance, reaction mixtures containing heat-killed bacteria had a similar LDCL profile that was characterized by continuous production of light over 180 minutes, whereas all reaction mixtures containing living bacteria underwent a precipitous decrease in light emission, which eventually resulted in a complete cessation of chemiluminescence. The PLC suspensions from different cattle did not respond to bacterial stimuli uniformly, with respect to the amplitude or detailed nature of the LDCL profile. The time that lapsed between the addition of living P haemolytica to PLC suspensions and the complete cessation of chemiluminescence varied for different cows.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Pasteurella haemolytica leukotoxin: physicochemical characteristics and susceptibility of leukotoxin to enzymatic treatment.

Sterile, concentrated culture supernatant from Pasteurella haemolytica (biotype A, serotype 1) strain 630 was subjected to physical, chemical, and immunologic treatments to determine their influence on leukotoxin (cytotoxin) activity contained in the supernatant. Each treated sample contained approximately 8 chemiluminescence inhibitory units of leukotoxin. Treatment effects were evaluated for their ability to inactivate leukotoxin activity. Leukotoxin activity in treated samples was determined by inhibition of the luminol-dependent chemiluminescence response of bovine neutrophils. Optimal leukotoxin synthesis by P haemolytica occurred when the bacteria were at the logarithmic growth phase, whereas stationary phase cultures contained minimal amounts of leukotoxin activity in their culture supernatant. Leukotoxin activity was heat labile; activity was substantially decreased when concentrated culture supernatant samples containing leukotoxin activity were incubated at 37 C for several hours. When concentrated culture supernatant was incubated at progressively decreasing temperatures, there was a progressive increase in the length of time that the leukotoxin retained its biologic activity. Samples stored at -70 C retained activity for at least 2 months. Leukotoxin activity was nondialyzable and was able to withstand considerable extremes in hydrogen ion concentration. Leukotoxin activity could not be pelleted when subjected to forces of 100,000 X g for 1 hour. Chemical and enzymatic studies suggested that P haemolytica leukotoxin contained carbohydrate and protein moieties. Chemical treatment with 0.2% sodium lauryl sulfate, 0.5% sodium deoxycholate, 7.5 mM EDTA and 8M urea with 8 mM 2-mercaptoethanol and enzymatic treatment with lipase, ribonuclease, and deoxyribonuclease had no discernible effect on leukotoxin activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Pasteurella haemolytica bacteriophage: identification, partial characterization, and relationship of temperate bacteriophages from isolates of Pasteurella haemolytica (biotype A, serotype 1).

Pasteurella haemolytica (biotype A, serotype 1) isolates (n = 15) from the upper respiratory tract of clinically normal cattle, as well as from lung lesions from cases of fatal bovine pasteurellosis, were examined for the presence of bacteriophage after irradiation with UV light. Treatment of all P haemolytica isolates with UV irradiation resulted in lysis of bacteria due to the induction of vegetative development of bacteriophages. The extent of growth inhibition and bacterial lysis in irradiated cultures was UV dose-dependent. Bacterial cultures exposed to UV light for 20 s reached peak culture density between 60 and 70 minutes after irradiation; thereafter, culture density declined rapidly, so that by 120 minutes, it was approximately 60% of the original value. When examined ultrastructurally, lytic cultures from each isolate revealed bacteriophages with an overall length of approximately 200 nm and that appeared to have a head with icosahedral symmetry and a contractile tail. Cell-free filtrate from each noninduced bacterial isolate was inoculated onto the other bacterial isolates in a cross-culture sensitivity assay for the presence of phages lytic for the host bacterial isolates. Zones of lysis (plaques) did not develop when bacterial lawns grown from the different isolates were inoculated with filtrates from the heterologous isolates.

Animals↗
PubMed1983

Concentration of clobetasone butyrate in aqueous humour.

The concentrations of clobetasone butyrate and betamethasone were measured in aqueous humour of patients undergoing cataract extraction 12.5 to 18.5 hours after application into the lower conjunctival sac of an ointment containing 0.1% of the steroid. Samples were assayed from 10 patients receiving clobetasone butyrate and 13 patients receiving betamethasone phosphate. There were measurable concentrations in only 2 samples in the former group, and both were 0.1 ng/ml. In the betamethasone group measurable concentrations were found in 11 samples, and the concentrations ranged from 0.5 to 20.3 ng/ml, with the highest concentrations between 12.5 and 13.5 hours after application. The concentration of betamethasone in the aqueous humour decreased by about 90% in the 6 hours from 12.5 to 18.5 hours after application. It is speculative as to whether it is these differences in pharmacokinetic behaviour, or other differences in biological or physicochemical properties, which are responsible for the minimal effect on intraocular pressure induced by clobetasone butyrate compared with betamethasone.

Aged↗
PubMed1981

Case studies of juvenile leukosis.

Clinical signs, hematologic values and gross pathologic changes in two calves with juvenile leukosis were similar to those described in other reports. Although there was considerable variation of hematologic values between the two calves, both were within the range previously determined for leukosis animals. Hematologic variations were observed in sequential samples obtained from one animal in this study during the course of the disease. These data would indicate that the extreme variations observed between animals in juvenile leukosis hemograms may be the result of aberrations caused by differences in relative sampling times. It is suggested that if hematologic parameters are to be meaningfully used as an aid in the diagnosis of juvenile bovine leukosis, multiple hematologic samplings should be taken and correlated with the disease state of the animal and time before death.

Animals↗
PubMed1980

Pseudotumor of the orbit and retroperitoneal fibrosis. A form of multifocal fibrosclerosis.

A patient with advanced renal failure and bilateral exophthalmos was found to have urinary obstruction caused by retroperitoneal fibrosis, as well as bilateral orbital pseudotumors. Pseudotumor of the orbit, especially when bilateral, has been associated with a wide variety of systemic conditions. Although the association of pseudotumor and retroperitoneal fibrosis is uncommon, any patient with bilateral orbital pseudotumor and renal insufficiency should be examined for the possible presence of a treatable urinary obstruction.

Aged↗
PubMed1979

The intraocular penetration of cefuroxime after parenteral administration.

Cefuroxime (Zinacef) is a new second generation cephalosporin which is resistant to beta-lactamases produced by both Gram-negative and Gram-positive organisms, with an antibacterial spectrum that includes practically all likely ocular pathogens except pseudomonas. It is shown to penetrate into the eye after intravenous (1.5g) or intramuscular (1 g) injection and achieve therapeutic concentrations, with absence of side effects. Cefuroxime is therefore a useful antibiotic for ophthalimic infections and should have a role in combination with gentamicin in intraocular infections, particularly those of unknown aetiology.

Adult↗