Biomedical subjects
Publications and source records attributed to M A Gordon.
Using [3H]quinuclidinyl benzilate as a specific cholinergic muscarinic ligand, it has been demonstrated that lymphocytes have muscarinic binding sites. There are approximately 200 sites per cell and the dissociation constant for quinuclidinyl benzilate is approximately 1 X 10(-9) M. Quinuclidinyl benzilate receptor binding is blocked by atropine and oxotremorine.
Pityrosporum pachydermatis was repeatedly isolated from portions of alopecic tissue from the throax and ears of a black bear cub (Ursus americanus). Yeastlike cells morphologically identical with those of P. pachydermatis were observed in stained tissue sections. This is the first reported association of this yeast with a member of the family Ursidae.
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Calcium activation of acetylcholine hydrolysis by bovine brain acetylcholinesterase (Acetylcholine hydrolase, EC 3.1.1.7) forms has been analyzed in terms of changes in kinetic constants and thermodynamic activation parameters. De-acetylation was determined to be the major rate-influencing step in acetylcholine hydrolysis by both 60 000- and 240 000-dalton forms of the brain enzyme and 10 mM Ca2+ increased the rate constant for this step (k+3) by approximately 30% for both forms. For the smaller acetylcholinesterase form the effects of Ca2+ on de-acetylation was equivalent to its effect on the overall rate constant (k) and occurred without an effect on pK. In the case of the 240 000-dalton species, the overall rate constant was increased by Ca2+ by 33% at pH 8.0 and 81% at pH 7.25 and involved a pK shift of -0.2 pH units. For both enzyme forms the rate constants for acetylation (k+2) were increased by Ca2+. Thermodynamic analysis suggested that Ca2+ activation of the acetylation step was entropically driven. Differences between the two enzymes forms in terms of Ca2+ appear to result from association of low molecular weight species.
Diffuse fluorescence in an indirect fluorescent-antibody test for antibody to Aspergillus fumigatus was eliminated by using germlings, rather than hyphae, as antigen. The modified method yielded diagnostic titers larger than or equal to 1:32 in 24 of 25 known cases, was highly specific, and showed good correlation with clinical status and results of immunodiffusion. This technique, which uses the germling antigen, inactivation of test serum at 59 +/- 1 degrees C, and anti-immunoglobulin G conjugate, is a sensitive, specific, and reliable quantitative indicator of aspergillosis and is useful in following the course of the disease.
Alterations in the morphologic and physiologic characters of 11 isolates of Pityrosporum orbiculare were noted upon prolonged maintenance in pure culture. Successive subculturing of each isolate resulted in its progressive conversion from globose (P. orbiculare) through ovoid to cylindrical (P. ovale) form. Globose forms utilized neither olive oil nor Tween 20 as a sole carbon source, nor KNO3 as a sole source of nitrogen, while ovoid and cylindrical forms utilized both of these carbon sources, and one of four strains of the cylindrical form assimilated KNO3. These results suggest that P. orbiculare and P. ovale are stages in the complex developmental cycle of a single species (Malassezia furfur), but the three names should be preserved until the life cycle is more fully understood.
In a recent 2-year period Dermatophilus congolensis infection, ranging from mild to very severe, was found in 15 white-tailed deer (Odocoileus virginianus) taken in southeastern New York State (12) adjacent New Jersey (2) and central Vermont (1). The host range for Dermatophilus congolensis is given.
Dermatophilus congolensis was established as the cause of dermatitis in 8 raccoons, as determined from examination of carcasses and untreated hides. Encrusted lesions were restricted to or more pronounced in the areas around the eyes, along the snout, and on the skin in the tarsal and carpal regions. The causative agent was demonstrated through direct examination of stained paraffin sections, isolation in pure culture, or examination of stained smears from lesions induced experimentally in rabbits with material from the affected raccoons.
Three forms of brain acetylcholinesterase were purified from bovine caudate-nucleus tissue and determined by calibrated gel filtration to have mol.wts. of approx. 120 000 (C), 230 000 (B) and 330 000 (A). [3H]Di-isopropyl phosphorofluoridate (isopropyl moiety labelled) was purified from commercial preparations and its concentration estimated by an enzyme-titration procedure. Brain acetylcholinesterase preparations and enzyme from eel electric tissue were allowed to react with [3H]di-isopropyl phosphorofluridate in phosphate buffer until enzyme activity was inhibited by 98%. Excess of [3H]di-isopropyl phosphorofluoridate that had not reacted was separated from the labelled enzyme protein by gel filtration, or by vacuum filtration or by extensive dialysis. The specificity of active-site labelling was confirmed by use of the enzyme reactivator, pyridine 2-aldoxime. The forms of brain acetylcholinesterase were calculted to contain approximately two (C) four (B) and six (A) active sites per molecule respectively. Acetylcholinesterase (mol.wt. 250 000) from electric-eel tissue was estimated to contain two active sites per molecule. Gradient-gel electrophoresis was used to confirm the estimation of molecular weights of brain acetylcholinesterase forms made by gel filtration. Under the conditions of electrophoresis acetylcholinesterase form A was stable, but form B was converted into a species of approx. 120 000 mol. wt. Similarly, form C of the brain enzyme was converted into a 60 000-mol.wt. form during electrophoresis. These results are in general accord with the suggestion that the multiple forms of brain acetylcholinesterase may be related to the aggregation of a single low-molecular-weight species.
In a patient with only meningitis, a septate hypha was seen in a Langhans giant cell, and the rarely pathogenic Aspergillus oryzae was cultured from the cerebrospinal fluid. Serologic results confirmed the diagnosis. The patient responded to therapy with amphotericin B and flucytosine.
Aureobasidium pullulans was repeatedly isolated from a cutaneous infection of a porcupine (Erethizon dorsatum). Tissue sections revealed fungal filaments similar to those of A. pullulans. This is the first reported association of A. pullulans with a natural infection of either wild or domesticated animals.
Infection by both Dermatophilus congolensis and Alternaria alternata was found in a 5 1/2-year-old, female white-tailed deer (Odocoileus virginianus). Encrusted lesions characteristic of dermatophilosis were observed on the hocks, flanks, and back. Giemsa-staining of smears of material from beneath the crusts revealed branching filaments, transversely and longitudinally divided into packets of coccoid cells typical of D congolensis. Hyphae morphologically consistent with those of A alternata were found in methenamine-silver- and hematoxylin-and-eosin-stained sections of tissue from the ears, flanks, and back. Nutrient agar cultures inoculated with tissue from an ear and hindlimb of the deer yielded, respectively, A alternata and D congolensis.
Two case reports add to the rare recorded instances of infection of man and other animals by Phoma or Phoma-like molds. Phoma cava was consistently cultured from aural dermatitis of a white-tailed deer (Odocoileus virginianus), and tissue sections of the ear revealed fragments of apparent pycnidial walls, as well as many septate hyphae. In the second instance, numerous Phoma-like pycnidia occurred in and upon the hairs of a young child, in a lesion initiated by Trichophyton infection.
The new Aspergillus differential medium distinguishes effectively between members of the Aspergillus flavus group and other Aspergillus species of interest in medical mycology.
Twin white-tailed deer (Odocoileus virginianus) fawns captured in Morris County, New Jersey, displayed papular, darkly pigmented scabs principally on the skin overlying the nasal bones, dentary, commissure of the lips and ears. Histopathological and bacterial examinations revealed Dermatophilus congolensis. The epidermitis caused by this bacterium apparently had developed within the first 12 to 14 days after birth and had begun to regress by one month of age. The location of the lesions suggested transmission during nursing from an infected doe. This is believed to be the first confirmed report of this zoonotic disease in white-tailed deer, with isolation of the etiologic agent, outside the State of New York. Epizootiological considerations are discussed.
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