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Biomedical subjects

D Armstrong

Publications and source records attributed to D Armstrong.

At least 559 records · Page 31Linked to original sources
PubMed1982

Examination of Pseudomonas aeruginosa-gentamicin discrepancies encountered in an Autobac I-disk diffusion comparison.

Seven Pseudomonas aeruginosa strains found to be susceptible to gentamicin by the Autobac I system and resistant by the Bauer-Kirby disk diffusion method were tested for the presence of mixed populations of cells. Double zones of inhibition randomly appeared on gentamicin disk diffusion plates, and susceptible and resistant subpopulations were isolated from these plates. Growth kinetic studies of separated strains and mixed subpopulations indicated that the susceptible organisms grew rapidly and were read as susceptible at 5 h with the Autobac I system. Resistant organisms entered a sustained lag phase and did not achieve sufficient turbidity to be read as resistant with the Autobac I system before 6 h. Thus, a false reading of susceptible could be obtained with the Autobac I system, depending on the ratio of susceptible organisms to resistant organisms selected for testing. A mixed susceptible and resistant population could be recognized by extending the incubation time of the Autobac I cuvette or by using other susceptibility methods to test isolates with light-scattering indexes of less than 1.0.

Drug Resistance, Microbial↗
PubMed1982

Minimal nephrotoxicity with cephalosporin-aminoglycoside combinations in patients with neoplastic disease.

Patients with cancer and suspected sepsis were treated in a prospective, randomized trial with one of four cephalosporin-aminoglycoside combinations: cephalothin and tobramycin; cephalothin and gentamicin; cefamandole and tobramycin; or cefamandole and gentamicin. Carbenicillin was added if the absolute granulocyte count was less than 1,000/mm3. Of 199 patients receiving 20 to more doses of an aminoglycoside and having serial determination of serum creatinines, nephrotoxicity developed in seven (3.5%) given any of the four combinations. There were no significant differences between patients receiving either cephalosporin or either aminoglycoside. Nephrotoxicity developed less frequently among children (2 or 125; 1.6%) than adults (5 of 74; 6.8%).

Adolescent↗
PubMed1982

Species identification of coagulase-negative staphylococcal isolates from blood cultures.

Coagulase-negative staphylococci generally are not fully identified, are called Staphylococcus epidermidis, and are considered contaminants when isolated from blood cultures. In a cancer hospital during 6 months, 46 patients had multiple blood cultures (mean, 3.1) which yielded coagulase-negative staphylococci. Species identification of these showed that 10 of the 46 (22%) were not S. epidermidis. Similarly, 96 coagulase-negative staphylococci isolated from only one of multiple blood cultures from patients and thought to be skin contaminants were identified. Of 96 of the staphylococci, 14 (16%) of the latter group were not S. epidermidis. Species found included S. haemolyticus, S. hominis, S. warneri, S. simulans, and S. xylosus. Eight isolates of these species were methicillin resistant, and all eight were mannitol fermenters. The results suggest that these species invasively infect cancer patients with the same frequency at which the species colonize. No one species was identified as being more pathogenic than the others. Routine species identification of coagulase-negative staphylococci from blood cultures of cancer patients contributed little to management except to occasionally distinguish multiple-episode culture contamination by different species from sustained bacteremia with the same species.

Adult↗
PubMed1982

Comparison of direct and standard microtiter broth dilution susceptibility testing of blood culture isolates.

Turbid broth (0.5 ml) from blood culture bottles was inoculated into 0.5 ml of brain heart infusion broth, incubated for 3 to 6 h, diluted 1:500 in distilled water, and then inoculated directly into microtiter broth dilution susceptibility trays to test for minimal inhibitory concentrations. The results were compared to the standard tests performed 24 h later on colonies from subculture plates. The minimal inhibitory concentrations measured by these two methods were compared in 1,875 organism-antibiotic tests. The two minimal inhibitory concentrations were identical in 86.0% and within one twofold dilution in 98.0% of the tests. An organism was judged to be susceptible by one method and resistant by the other in 13 tests (0.7%). These 13 discrepancies were distributed among several organism-antibiotic combinations; no more than two were seen for any one combination. Highly accurate susceptibility testing can be achieved by using direct inoculation of turbid blood culture broths.

Anti-Bacterial Agents↗
PubMed1982

Bone infection caused by debaryomyces hansenii in a normal host: a case report.

Debaryomyces hansenii was isolated from a cystic lesion in the distal tibia of a healthy 23-year-old woman. Ascospores were demonstrated when the organism was incubated at 25 but not at 30 degrees C. Electron microscopy was necessary to demonstrate the warty surface of the ascospore wall. Growth was inhibited in vitro by low concentrations of amphotericin B, 5-fluorocytosine, miconazole, and ketoconazole. Four previous cases of infection caused by Debaryomyces spp. and one caused by the related fungus Torulopsis candida were reviewed.

Adult↗
PubMed1982

Canine hereditary ceroid lipofuscinosis.

Dogs with an inherited form of ceroid lipofuscinosis are ataxic, blind and demented. During the disease process, they undergo severe cerebrocerebellar atrophy with storage of autofluorescent, lipid peroxide-positive reacting substances whose ultrastructure resembles 'fingerprint' patterns of membranous lamellae. The retina and RPE also undergo pathologic changes. Most important is the inverse relationship between loss of RPE melanin and increased deposition of ceroid. These pathological events in brain and eye lead to altered EEG, ERG and VEP activity. This inbred strain of English setters fulfills essentially all the criteria as a model for the human disease and will prove useful in the future for therapeutic trials.

Animals↗
PubMed1982

Adverse reactions to myelography with metrizamide in infants, children and adolescents. II. Local injury caused by lumbar puncture and injection of contrast medium.

A series of 605 myelographies with metrizamide was reviewed to assess the risk of local injury caused by the puncture and injection of metrizamide. A lesion below the normal level of the medullary conus was found in 139 patients, and in 10 of these the needle went into or through the lesion. One patient developed paraplegia due to the puncture and injection, no other patient had any symptoms. It is concluded that in spite of the risk, lumbar puncture should be the routine procedure for myelography with metrizamide in children.

Adolescent↗
PubMed1982

Opportunistic infection in previously healthy women. Initial manifestations of a community-acquired cellular immunodeficiency.

Opportunistic infections and unusual tumors have been reported in an unprecedented outbreak of community-acquired cellular immune deficiency among homosexual and drug-abusing men. We report five women with the same syndrome. The women were residents of metropolitan New York City closely associated with drug abuse either by personal use (our patients) or close sexual contact with an abuser (one patient). One patient was bisexual. All five patients developed Pneumocystis carinii pneumonia as well as combinations of other opportunistic infections including oral candida, disseminated mycobacteria, and ulcerative herpes simplex infections. All patients had marked depression of cellular immune function. Three patients died. The appearance of this syndrome in women has important implications with regard to the epidemiology and etiology of this emerging syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1982

The antifungal activity of carrier peptides, L-arginyl-X-L-phenylalanine, containing amino acid antagonists or atypical non-biogenic D-amino acids in the central position.

Eleven analogues of L-arginyl-D-allo-threonyl-L-phenylalanine, a naturally occurring peptide with antifungal activity, were synthesized. Two tripeptides of the form L-arginyl-X-L-phenylalanine (X = p-F-DL-phenylalanine or m-F-DL-tyrosine) inhibited Aspergillus fumigatus and Aspergillus flavus. In comparison with the free antagonists, the tripeptide-bound antagonists were more active against Candida-albicans-isolates which means that the amino acid sequence may serve as carrier function: it enhances delivery or uptake of the antimetabolite.

Antifungal Agents↗
PubMed1981

Systemic infection with Trichosporon cutaneum in a patient with acute leukemia: report of a case.

A case of disseminated infection with Trichosporon cutaneum, a fungus that causes white piedra, is described. The patient, a 58-year-old barber with acute leukemia, had fever, myalgias and skin lesions. He was receiving cytotoxic drug therapy and prednisone, was severely neutropenic and was being treated with broad spectrum antibiotics. Blood cultures and a biopsy of the skin lesion grew T. cutaneum. He died despite amphotericin B therapy. At autopsy, widespread infection with T. cutaneum was present. T. cutaneum is another fungus capable of causing widespread systemic disease in the immunocompromised host.

Amphotericin B↗
PubMed1981

Fungemia in the immunocompromised host. Changing patterns, antigenemia, high mortality.

Fungemias were reviewed in 110 immunocompromised patients hospitalized between November 1, 1974, and December 31, 1977, a Memorial Sloan-Kettering Cancer Center (MSKCC). The incidence of Candida tropicalis fungemia increased each year. Seventy-six percent of the patients with C. tropicalis fungemia and 32.5 percent of those with C. albicans fungemia had either leukemia or lymphoma. Seventy-seven percent of the C. parapsilosis fungemias were related to total parenteral nutrition. Thirty-seven percent of the patients with C. albicans fungemia were receiving oral prophylactic nystatin therapy. The source of fungemia was often difficult to determine: in 60 percent of the patients, only blood cultures were positive for C. tropicalis or Torulopsis glabrata; no cultures were positive for the fungus from any other site before the episode occurred. Serologic tests, including a highly sensitive passive hemagglutination test, showed fourfold increases in titer only inconsistently. A passive hemagglutination-inhibition test for circulating antigen was positive in 50.9 percent of 57 patients with fungemia who were tested and may be a valid indication for treatment. Fungemia usually represented a severe and often fatal disease. The over-all mortality of the 110 patients with fungemia was 79 percent whereas only 23 percent of the patients with C. parapsilosis fungemia died. Among the patients who received more than 200 mg of amphotericin B, 71 percent died despite treatment.

Antigens, Fungal↗
PubMed1981

Invasive aspergillosis. Progress in early diagnosis and treatment.

Ninety-one patients with documented invasive infections due to an Aspergillus species were identified at Memorial Sloan-Kettering Cancer Center from July 1, 1971, through December 31, 1976. Of the 29 patients in whom the diagnosis was made during life, 10 had successful treatment and survived the Aspergillus infection by two to 17 months. An immunodiffusion test was useful in the early diagnosis of invasive aspergillosis, and in 11 patients in whom the diagnosis was supported by seroconversion and who underwent treatment, the survival rate was 64 percent. Cultures of respiratory secretions were not reliable because they often reflected only colonization. In one year, only 9 percent of he patients with Aspergillus species isolated from the sputum had an invasive infection. The lung was the commonest site of involvement, 91 percent of the patients having pulmonary lesions. The most frequently affected extrapulmonary organ was the brain (18.3 percent). Eight patients had nonpulmonary aspergillosis as the only manifestation of this infection. Most of the 91 patients had hematologic neoplasms as the underlying disease, and neutropenia and antibacterial therapy preceded the diagnosis of aspergillosis in the majority of cases.

Adolescent↗
PubMed1981

"Onion bulb" formation associated with a solitary neoplasm of the eighth nerve sheath.

Audiometric patterns associated with retrocochlear disorders include abnormal adaptation, delay of auditory evoked potential latencies, and characteristic abnormalities of speech intelligibility functions. The anatomic substrate of these psychoacoustic and electrophysiologic abnormalities is unknown. This paper describes the incidental observation of "onion bulbs" in a solitary neoplasm involving the eighth nerve sheath and in the cochlear nerve lateral to the neoplasm. Such hypertrophic neuropathy in the eighth nerve has not been described previously. This occurrence raises the question of sequential demyelination and remyelination in a neoplasm-bearing nerve as a possible histopathologic correlate to retrocochlear dysfunction.

Cranial Nerve Neoplasms↗
PubMed1981

Enhancement of formation of the esophageal carcinogen benzylmethylnitrosamine from its precursors by Candida albicans.

Previous studies in Linxian, an area of China with a high incidence of esophageal carcinoma, showed that fungal infections are common in the esophageal epithelium of patients with either premalignant changes or early esophageal carcinoma. Fungi of the genus Candida were the most frequent invaders. In these areas nitrate and nitrite are often present in high concentrations in drinking water and staple grains. The present studies have established the ability of Candida albicans to augment the nitrosative formation of the esophagus-specific carcinogen, benzylmethylnitrosamine (NBMA; N-nitroso-N-methylbenzylamine). Stationary C. albicans cultures, with pH held at 6.8, were incubated with the precursors of NBMA, benzylmethylamine (BMA; N-methylbenzylamine) and NaNO(2). There was a significant increase in the amount of NBMA formed in these cultures, compared to precursors-only controls. The amount of NBMA synthesized depended on fungal cell number. Exponentially growing cultures were also able to cause NBMA formation. The identity of the NBMA was confirmed by high-performance liquid chromatographic coelution with authentic NBMA in three solvent systems and by mass spectroscopy. Boiled cells and conditioned medium in which cells had been incubated were not effective in enhancing nitrosation. Cultured Candida released acidic metabolites that reduced the pH of the medium when only a low concentration of buffer was present. Spontaneous nitrosation of BMA was enhanced under these acidic conditions. Thus, C. albicans infecting the esophageal epithelium could cause local formation of NBMA by both cell-mediated catalysis and extracellular decrease in pH.

Benzylamines↗
PubMed1981

Delayed toxicity and delayed neurotoxicity of phosphonothioate and phosphonothioate esters.

The delayed neurotoxicity to hens and delayed toxicity to rats of the isomeric trimethyl phosphonothioates, trimethyl phosphate, and a series of the methyl and ethyl esters of methyl-, ethyl-, and phenylphosphonate and phosphonothioates were examined. All the O,O-dialkyl phosphonothioates, phosphorothioates, and their corresponding oxons were relatively nontoxic to rats, with oral LD50 values greater than the 150-450 mg/kg tested. The O,S-dialkyl phosphorothioate esters were highly acutely toxic. The rat acute LD50 values for O,S-dimethyl methylphosphonothioate and O,S-diethyl ethylphosphonothioate were 3 and 8 mg/kg. O,S-Diethyl ethylphosphonothioate and O,O, S-trimethyl phosphorothioate were the only compounds tested that showed delayed toxicity to rats. The delayed LD50 values for these two compounds were 7 and 15-20 mg/kg, respectively, with rats dying 3-22 d after treatment The delayed toxic effects were associated with continual loss of weight, reaching 18-46% at the time of death. Of this series of compounds, only O,O-diethyl phenylphosphonothioate and its oxon showed delayed neurotoxicity to hens 45 d after treatment. The minimum effective dose for these two compounds was 25 mg/kg.d administered ip for 10 d. These findings suggest that delayed neurotoxicity in hens is not due to the same mechanism as delayed toxicity in rats.

Animals↗