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Biomedical subjects

A D Alexander

Publications and source records attributed to A D Alexander.

At least 19 recordsLinked to original sources
PubMed1996

Biological degradation and composition of inedible sweetpotato biomass.

Many challenges are presented by biological degradation in a bioregenerative Controlled Ecological Life Support System (CELSS) as envisioned by the U.S. National Aeronautics and Space Administration (NASA). In the studies conducted with biodegradative microorganism indigenous to sweetpotato fields, it was determined that a particle size of 75 microns and incubation temperature of 30 degrees C were optimal for degradation. The composition of the inedible biomass and characterization of plant nutrient solution indicated the presence of potential energy sources to drive microbial transformations of plant waste. Selected indigenous soil isolates with ligno-cellulolytic or sulfate-reducing ability were utilized in biological studies and demonstrated diversity in ability to reduce sulfate in solution and to utilize alternative carbon sources: a lignin analog--4-hydroxy, 3-methoxy cinnamic acid, cellulose, arabinose, glucose, sucrose, mannitol, galactose, ascorbic acid.

Biodegradation, Environmental↗
PubMed1992

Serious professional misconduct arising out of dental anaesthesia and sedation.

This paper reviews three recent decisions of the Judicial Committee of the Privy Council on appeal from decisions of the Professional Conduct Committee of the General Dental Council, in which questions of general anaesthesia, sedation and resuscitation were raised. The recommendations of the Poswillo Report on general anaesthesia, sedation and resuscitation in dentistry of March 1990 are considered with respect to these three cases, and an assessment made as to whether or not the incidents which gave rise to them would have occurred had the recommendations been implemented. The implications of the Poswillo Report for the maintenance of professional standards of conduct by the General Dental Council in relation to the use of general anaesthesia, sedation and resuscitation are discussed.

Anesthesia, Dental↗
PubMed1986

Penicillins, cephalosporins, and tetracyclines in treatment of hamsters with fatal leptospirosis.

A predictable 6- to 7-day course of a fatal Leptospira interrogans serovar bataviae infection in experimentally infected mature 110- to 150-g hamsters was used to evaluate the therapeutic efficacy of conventionally used and newer antibiotics. Active drugs were ampicillin, bacampicillin, cyclacillin, piperacillin, mezlocillin, doxycycline, chlortetracycline, cefotaxime, and moxalactam. Cephalexin, cefadroxil, cefamandole, and cefoperazone showed little or no activity in preliminary studies. In delayed treatment studies, all nine active drugs prevented death of hamsters even when treatment was delayed until 1 to 2.5 days before expected time of death. Leptospires in kidneys of surviving animals could be demonstrated in one or more hamsters treated with doxycycline, chlortetracycline, cyclacillin, and piperacillin, but in none of the animals treated with ampicillin, bacampicillin, mezlocillin, cefotaxime, and moxalactam. The potential usefulness of newer penicillins and cephalosporins, as well as ampicillin, chlortetracycline, and doxycycline, for treatment of severe leptospirosis is reported.

Animals↗
PubMed1986

Gellan gum as a substitute for agar in leptospiral media.

An albumin polysorbate semisolid medium (Ellinghausen McCullough Johnson Harris medium) gelled with gellan gum (Gelrite; Kelco Div., Merck & Co., Inc.) compared favorably with conventional agar media for the cultivation of both pathogenic and saprophytic leptospires. The gellan gum medium supported the growth of all 18 leptospiral strains studied which included an array of serovars with various fastidious growth characteristics. Gellan gum medium was also used advantageously as a long-term maintenance medium; 9- to 12-month-old cultures still contained viable organisms. The colonial growth in gellan gum plating medium of six representative strains was consistent with previously described colonial growth on agar plating media. In addition, gellan gum medium appeared to be an excellent medium for the recovery of leptospires from the blood, liver, and kidneys of hamsters experimentally infected with a virulent Leptospira interrogans serovar bataviae strain. As few as 1 to 10 organisms in the infective tissue could be recovered in semisolid Ellinghausen McCullough Johnson Harris-gellan gum medium. The antigenicity did not appear to be affected by growth in gellan gum medium. The hamster-virulent strain of L. interrogans serovar bataviae isolated from a moribund hamster maintained its virulence after 10 sequential passages in gellan gum medium. Gellan gum medium can be a valuable adjunct to currently used cultural procedures.

Agar↗
PubMed1984

Leptospirosis in laboratory mice.

The obituary for William A. Altemeier, Jr. (4 May, p. 525), was incorrect. Dr. Altemeier was chairman of the Department of Surgery at the University of Cincinnati.

Animals↗
PubMed1975

Pathogenic leptospiras isolated from Malaysian surface waters.

Pathogenic leptospiras (1,424) isolated from natural waters and wet soils in Malaysia comprised 29 different serovars (synonym serotypes). All except two of the serovars had been found previously in Malaysia. The exceptional serovars were werrasingha, an Autumnalis serogroup member originally isolated in Ceylon, and a new serovar designated evansi. Serovar evansi had serological affinities with serovar ranarum which was isolated from the kidney of a frog in Iowa. The large variety of serovars found in jungle areas was consistent with similar previous findings of diverse serovar infections in troops who had operated in Malaysian jungles.

Agglutination Tests↗
PubMed1972

Zoonotic infections in military scout and tracker dogs in Vietnam.

Significant levels of antibodies indicative of a variety of zoonotic infections were demonstrated in sera collected from 64 U.S. military scout and tracker dogs after service in the Republic of Vietnam (RVN). Scrub typhus antibodies were found in 45% of the specimens, melioidosis in 19%, group B arbovirus in 49%, and leptospirosis in 62%. Only 38% of the seropositive reactions for leptospirosis could be related to overseas infections. Tests were conducted on paired sera obtained from 32 of the dogs before service in RVN. Significant increases in titer were demonstrated with scrub typhus, melioidosis, leptospirosis, plague, group B arbovirus, and Rickettsia canada antigens. After 2 to 6 months of service in RVN, 8 of 19 dogs developed antibody titers to at least one of four zoonotic diseases. Only 3 of 45 dogs with 7 or more months of service failed to develop antibodies to one or more of the agents. The serological findings pose questions on the potential epidemiological importance and veterinary significance of scrub typhus, group B arbovirus, leptospirosis, and melioidosis infections in dogs.

Animals↗
PubMed1972

Research needs in leptospirosis.

Leptospirosis is a widespread infection of man and animals, and locally it assumes considerable importance as a public health and economic problem. It is an important occupational infection among persons working with animals or in environments that may be contaminated by infected animals. In recent years, considerable attention has been devoted to this infection but efforts to control and eliminate it, especially from natural foci, are hindered by gaps in our knowledge. This memorandum is a review of recent progress and current problems in leptospirosis research, with special reference to taxonomy, epidemiological methods, and control measures. Certain aspects of the basic biology of leptospires that are relevant to these topics are also discussed.

Agglutination↗
PubMed1971

In vitro susceptibility of strains of Pseudomonas pseudomallei to rifampin.

Reported high activity of rifampin for Pseudomonas pseudomallei could not be verified by extensive in vitro tests conducted with 31 recently isolated strains. Minimal inhibitory concentrations of rifampin were 25 mug/ml for three strains and greater than 25 mug/ml for 28 strains. Rifampin had relatively poor in vitro activity when compared with tetracycline drugs and chloramphenicol antibiotics now commonly used for treating melioidosis.

Chloramphenicol↗
PubMed1971

Cross-neutralization of leptospiral hemolysins from different serotypes.

Cross-neutralization studies on leptospiral hemolysins from strains of two antigenically different serotypes, pomona and canicola, were conducted in sheep. A third strain of serotype hardjo that does not produce hemolysin and is antigenically distinct was included for control purposes. Concentrated hemolysins, prepared from supernatant fluids of canicola or pomona cultures, produced hemolytic anemia in sheep after intravenous injection. Sheep previously infected with hemolysin-producing strains were refractory to effects of homologous or heterologous hemolysins. On the other hand, infection with hardjo did not confer immunity to the action of hemolysins. Hemolysin-neutralizing antibodies were demonstrable in sheep previously infected with pomona or canicola only after challenge with homologous or heterologous hemolysins. Cross-neutralization between two hemolysins were demonstrable in vitro. Hemolysin-neutralizing antibody titers did not correlate with agglutinin titers. Concentrated supernatant fluid of the hardjo culture provoked toxic reactions predominantly in sheep previously infected with pomona or canicola. The causes of these untoward reactions were not determined.

Albuminuria↗
PubMed1970

Serological diagnosis of human melioidosis with indirect hemagglutination and complement fixation tests.

An indirect hemagglutination (IHA) test and a complement fixation (CF) test were evaluated from test results on sera from 212 human melioidosis patients of which 119 were culturally proved cases. Significant antibody titers (IHA titers of 1:40 or greater and CF titers of 1:4 or greater) were demonstrated with either test in all except five patients. IHA and CF titers ranged as high as 1:20,480 and 1:1,024, respectively. Antibodies were usually demonstrated by both tests 1 week after onset of disease. Transient seronegative reactions during the course of disease were seen in sera of approximately 19% of the patients with either IHA and CF but rarely with both tests. High titers in either test were obtained by the third week of disease and reached maximum levels in 4 to 5 months. Titers usually were detectable for 9 or more months. Antibodies were detected by IHA and CF tests in 80 to 100% of the sera obtained at various time intervals from 9 months to 2 or more years after disease onset. Antibody persistence occurred in patients who had a short disease course, as well as in patients with prolonged, complicated infections. The IHA test had excellent specificity when evaluated with normal human sera and diverse antimicrobial sera from hyperimmunized rabbits and human patients. The CF antigen appeared to contain common antigens with some but not all types of Pseudomonas aeruginosa. The specificity of the CF antigen could be enhanced without appreciable effect on its sensitivity by use of a titer of 1:8 in lieu of 1:4 as a criterion for a significant reaction. Either test could be used advantageously for the laboratory diagnosis of melioidosis.

Animals↗
PubMed1970

Nucleic acid similarities among Pseudomonas pseudomallei, Pseudomonas multivorans, and Actinobacillus mallei.

Annealing experiments on membrane filters were carried out with deoxyribonucleic acids (DNA) from selected strains of the nomen-species of Pseudomonas, Actinobacillus, Chromobacterium, and Micrococcus, with the use of DNA of Pseudomonas pseudomallei and Actinobacillus mallei as reference materials. Under the usual conditions employed in these experiments, the results were not quantitatively reproducible. Incorporation of dimethylsulfoxide (DMSO) into the incubation medium greatly increased differences in comparative binding. DNA binding in agar matrices was examined in the presence and absence of DMSO at various incubation temperatures. It was found that the greatest specificity, stability, and total binding for DNA containing high amounts of guanine and cytosine occurred in the presence of DMSO. Under the most stringent annealing conditions permitted in agar, DNA species from P. pseudomallei and A. mallei in the presence of DMSO demonstrated interspecific relative bindings of 76 to 86% when compared to the homologous reactions. The thermal elution midpoints (E(m)) of these duplexed interspecific DNA species were quite close to the homologous E(m) values. The relative bindings of P. multivorans DNA types to either reference DNA ranged between 6 to 27%, and the E(m) values were 4 to 7 C less than those for the homologous reactions.

Actinobacillus↗
PubMed1970

Melioidosis in imported non-human primates.

In 1969, five cases of melioidosis in three separate outbreaks were diagnosed in nonhuman primates in the United States. In the first outbreak, two stump-tailed macaque monkeys (Macaca arctoides) developed signs of the disease approximately 6 months after purchase. A third animal, a chimpanzee (Pan troglodytes), probably acquired its infection from one of these monkeys. Two other unrelated cases involving a pig-tailed monkey (Macaca nemestrina) and a rhesus monkey (Macaca mulatta) were diagnosed. These monkeys had been imported 3 years and 6 months, respectively, prior to the recognized onset of their disease. These cases represent the first known occurrences of spontaneous melioidosis in nonhuman primates in the United States.

Animals↗
PubMed1969

Deoxyribonucleic acid base composition and homology studies of Leptospira.

Four distinct genetic groups of leptospiras were demonstrated among selected pathogenic and "biflexa" serological types. Pathogenic leptospiras could be divided into two groups on the basis of per cent guanine + cytosine (GC) in their deoxyribonucleic acid (DNA). One group had 36 +/- 1%, the other 39 +/- 1%. The biflexa strains had DNA of 39 +/- 1% GC, but were further separated into two groups on the basis of DNA-annealing tests. Strains within groups had a high degree of specific duplex formation (75% binding or more with reference to the homologous DNA). There was little or no genetic relatedness between strains of the four groups (less than 10% DNA homology). The thermal elution midpoint of heterologous DNA duplexes was always lower than the homologous reaction. The serological relationships among strains were not meaningful in terms of relatedness determined by specific duplex formation.

Adenine↗