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Biomedical subjects

W D Richards

Publications and source records attributed to W D Richards.

At least 19 recordsLinked to original sources
PubMed1991

Hearing aid coupler output level variability and coupler correction levels for insert earphones.

HA coupler type SPLs were independently determined by two experimenters for five repeated measurements with and without replacement of two ER-3A and two EARTONE 3A insert earphones. Measurements were made using a B&K DB-0138 coupler configured as an HA-1, HA-2 earphone coupler and HA-2 earphone coupler with entrance through a rigid tube referred to as the DB-0138 coupler. The HA-1, HA-2, and DB-0138 SPLs were found to be very stable (+/- 0.2 dB) for all intra- and interexperimenter measurements for each insert earphone and coupler type from 125 to 8000 Hz. Averaged across both experimenters and all repeated measurements, the mean HA-1 and HA-2 coupler SPLs were similar for each insert earphone from 125 to 8000 Hz. The mean HA-1, HA-2, and DB-0138 coupler SPLs were similar for each insert earphone from 125 to 2000 Hz; however, from 3000 to 8000 Hz the DB-0138 coupler SPLs were higher than the HA-1 and HA-2 coupler SPLs for each insert earphone. This occurred because of the geometrical differences between the insert earphone to coupler connections and coupler types. The HA-1 minus DB-0138 and HA-2 minus DB-0138 coupler SPL differences, or coupler correction levels, could be explained by quarter-wave resonances and stepped-diameter tubing systems creating acoustic horn effects.

Auditory Threshold↗
PubMed1983

Preservation of tissue specimens during transport to mycobacteriology laboratories.

Chloramine-T and sodium borate solutions were evaluated for their effectiveness in preserving Mycobacterium bovis and controlling the growth of non-mycobacterial contaminants on tissue specimens during transport to laboratories. The number of culturable M. bovis cells in suspension was reduced by 5.1 log10 upon exposure to chloramine-T solution and by less than 1 log10 upon exposure to sodium borate solution for 7 days. Reinoculation of laboratory media (because of overgrowth by non-mycobacterial contaminants) was required for 52.6% of 190 routine bovine tissue specimens shipped refrigerated in chloramine-T solution and for 6.1% of 520 specimens shipped unrefrigerated in sodium borate solution. M. bovis was isolated from bovine tissue stored in sodium borate solution at 23 degrees C for 17 weeks and at 4 degrees C for 25 weeks. Unrefrigerated sodium borate solution has been used successfully to ship tissue specimens to our laboratory for the past 11 years.

Animals↗
PubMed1983

Isolation of Mycobacterium kansasii from lymph nodes of cattle in the United States.

The isolation of 6 strains of Mycobacterium kansasii from bovine lymph nodes is reported. Occasional isolations of this organism from cattle lymph node lesions provides further evidence of its pathogenicity in domestic animals. The isolates were similar as determined by biochemical and serologic examinations. Histopathologic changes induced by this organism relative to those by M bovis and factors regarding source of infection are discussed.

Animals↗
PubMed1981

Mycobacterium paratuberculosis in the semen and genital organs of a semen-donor bull.

Mycobacterium paratuberculosis, the cause of Johne's disease, was isolated from the feces of a donor bull in an artificial insemination stud. During isolation and observation for 21 months, the organism was recovered from all of 26 fecal samples and from 8 of 31 semen samples. At necropsy, it was isolated from the intestine and adjacent lymph nodes, lung, spleen, seminal vesicles, and prostate gland but not from the testicles. We concluded that routine fecal cultures at bull studs will reveal infected bulls before they become genitally infected and shed M paratuberculosis in semen.

Animals↗
PubMed1981

Informal advice- and information-seeking between physicians.

Presently little is known or understood regarding the informal advice- and information-seeking behavior which occurs between physicians. In this paper the authors present an assessment of the quantity, quality, and patterns of direct peer communication in a county's physician population. All physicians within a country were mailed a sociometric questionnaire comprised of two questions. The data from the questionnaire revealed that colleague interaction occurs on a regular and frequent basis and is of considerable value to the physician seeking advice and information. An analysis of the communication patterns distinguished six of the country's physicians as opinion leaders. These findings illustrate the strength of informal communication among physicians and their opinion leaders. This phenomenon may be a key element in facilitating the physician's translation of medical advances into improved patient care with the least delay possible.

Communication↗
PubMed1981

Effects of physiol and chemical factors on the viability of Mycobacterium paratuberculosis.

Alternative methods of storing bovine fecal specimens for delayed culture of Mycobacterium paratuberculosis was studied. Significant (P less than 0.05) losses of viability were sustained by storage at 23 degrees C for 10 days and by treatment with 0.03 Zephiran for 4 and 10 days. Losses were moderate after storage at -70 degrees C for 15 weeks but significant (P greater than 0.05) after storage at 23 degrees C for 4 days. The alternative methods were compared with the standard method of processing specimens upon receipt and after 2 days in transit. Fecal specimens from 18 cattle were cultured.

Animals↗
PubMed1979

Bovine tuberculosis in the United States and Puerto Rico: a laboratory summary.

Mycobacteria were isolated from 14.3% of the tissues submitted to the National Veterinary Services Laboratories over a 5-year period (July 1, 1972, to June 30, 1977). The isolates were identified by drug susceptibility, and biochemical and serologic tests. Mycobacterium bovis isolated from tissues of cattle originating in 32 states and Puerto Rico accounted for 78% of the acid-fast isolations. Of the Mycobacterium bovis isolates, 4% were from tissues in which no microscopic tuberculous granulomas were observed on examination of tissue sections. Of the 119 Mycobacterium avium isolates, 18 were serotype 1, 44 were serotype 2, and 45 isolates represented 12 other serotypes.

Animals↗
PubMed1977

Mycobacteria isolated from exotic animals.

Mycobacteria were isolated from 263 of 474 specimens submitted from captive exotic (nondomesticated) animals over a 5-year period. Mycobacterium avium was isolated from 128 animals originating in 13 states and the District of Columbia; serotype 1 accounted for 65 of the isolations. Mycobacterium bovi was isolated from 74 animals in 7 zoos, 7 game parks, and 4 primate colonies in 1, states: Mycobacterium tuberculosis was isolated from 29 animals originating 9 stats; and Mycobacterium fortuitum, Mycobacterium chelonei, Mycobacterium scrofulaceum, and Mycobacterium spp. The widespread occurrence of tuberculosis in exotic animals maintained in captivity emphasizes the public health importance of these infections.

Animal Population Groups↗
PubMed1977

Effect of freezing on the viability of Mycobacterium paratuberculosis in bovine feces.

Three bovine fecal specimens were cultured for Mycobacterium paratuberculosis before freezing and after frozen storage at -70 degrees C for 3 and 15 weeks. The losses in viability from 0 to 3 weeks of storage were significant (P = 0.01) for all three samples. The losses in viability between 3 and 15 weeks of storage were not significant (P greater than 0.05) for two specimens in which the M. paratuberculosis occurred naturally, but the loss was significant (P = 0.01) in a simulated specimen (M. paratuberculosis culture added to feces from a healthy cow).

Animals↗
PubMed1975

Physical-chemical properties of precipitated and fractionated allergens from Mycobacterium bovis.

Seven allergens were prepared from cultures of Mycobacterium bovis. The culture filtrates were divided in half and each aliquot precipitated with either ammonium sulfate or trichloroacetic acid to prepare purified protein derivatives (PPD). These samples of PPD-bovis were analyzed for nitrogen, carbohydrate, RNA and DNA. Physical tests, such as: cellulose acetate electrophoresis, disc gel electrophoresis, ultracentrifugation, isoelectricfocusing and gel filtration were also performed. Precipitation with ammonium sulfate provided PPD's with less impurities than those precipitated with trichloroacetic acid although there was little difference in the allergenic activity of the products precipitated by either method. Several lots of PPD-bovis were fractionated by means of ultrafiltration and the fractions analyzed by many of the above chemical and physical tests as well as tests for amino acid composition and allergenic activity. The greatest amount of protein was found in the fractions with an apparent molecular weight in excess of 300,000. The carbohydrate was usually distributed in proportion to the amount of protein in each fraction while the nucleic acids were predominately found in the higher molecular weight fractions. The amino acid analysis and allergenic activity of the various molecular weight fractions provided data that would support the theory that the various fractions are polymers of a small molecular weight sub-unit. The number of amino acid residues were calculated and the minimum molecular weight of the tubercular protein estimated to be 8700. The estimated molecular weights of the fractions and the amino acid data concur with those previously reported for proteins from other mycobacteria.

Allergens↗
PubMed1975

Isolation and identification of mycobacteria from porcine tissues: a three-year summary.

Mycobacteria were isolated from 1,591 (78%) of 2,036 porcine tissues submitted to Veterinary Services Laboratories over a 3-year period (July 1, 1971, to June 30, 1974). The isolates were identified by biochemical and serologic tests. Of the 1,547 Mycobacterium avium isolates, 452 were serotype 1, 728 were serotype 2, 60 were serotyped 4, 110 were serotype 8, and 51 were serotyped 10; 36 isolates represented 11 other serotypes; 65 isolates shared antigens with more than one serotype; and 45 isolates, untypabley serologic methods, were identified by pathogenicity in chickens as M avium. Mycobacterium bovis was isolated from 15 tissues; Mycobacterium fortuitum, from 3; and Mycobacterium paratuberculosis, Mycobacterium scrofulaceum, and Mycobacterium xenopi were each isolated from single specimens.

Animals↗
PubMed1974

Comparison of six methods for isolating mycobacteria from swine lymph nodes.

Six laboratory methods were compared for isolating acid-fast bacteria. Tuberculous lymph nodes from each of 48 swine as identified by federal meat inspectors were processed by each of the methods. Treated tissue suspensions were inoculated onto each of eight media which were observed at 7-day intervals for 9 weeks. There were no statistically significant differences between the number of Mycobacterium avium complex bacteria isolated by each of the six methods. Rapid tissue preparation methods involving treatment with 2% sodium hydroxide or treatment with 0.2% zephiran required only one-third to one-fourth the processing time as a standard method. There were small differences in the amount of contamination among the six methods, but no detectable differences in the time of first appearance of M. avium complex colonies.

Alkanes↗
PubMed1972

Inhibition of fungal growth in the cultural isolation of mycobacteria.

Antifungal antibiotics were compared to determine their usefulness in primary mycobacterial cultures. Amphotericin B was found to be more effective in preventing fungal growth from bovine fecal specimens than were cycloheximide, nystatin, and tetracycline. Amphotericin B did not affect the growth rate of the following Mycobacterium species: M. avium, M. bovis, M. intracellulare, M. paratuberculosis, M. phlei, or M. tuberculosis, but it inhibited the growth of M. fortuitum. There was no observable effect on numbers of colonies of M. paratuberculosis on primary isolation from fecal specimens. It is recommended that, for the primary isolation of pathogenic mycobacteria from specimens likely to contain fungi, the inoculum should be pretreated with benzalkonium chloride, followed by mixing with amphotericin B or inoculation onto media containing amphotericin B.

Amphotericin B↗
PubMed1972

Mycobacterial agglutination-inhibition test.

The mycobacterial agglutination-inhibition test (MAIT) is described as a modification of the mycobacterial agglutination of Schaefer (MATS). It is an organized assemblage of absorption and agglutination tests which is especially useful in the identification of Mycobacterium avium isolates normally excluded from serological identification because of unstable cell suspension characteristics. The identity of 100 unstable M. avium and 3 unstable Mycobacterium intracellulare isolates was determined by the MAIT method and by animal pathogenicity tests. The comparability of the MAIT and MATS methods was demonstrated by testing 10 stable M. avium and 10 stable M. intracellulare isolates by both methods and obtaining the same serological identification for each culture. The reproducibility of the MAIT was confirmed when the same result was obtained in three consecutive tests on each of the 123 cultures used in this evaluation.

Absorption↗