Characterization of a possible tRNA synthetase gene from Onchocerca volvulus.
Explore the source record for details and available documents.
Amino Acid Sequence↗
Biomedical subjects
M A Kron
Publications and source records attributed to M A Kron.
Human infestation with Cochliomyia hominivorax, the New World screwworm.
Explore the source record for details and available documents.
Child↗
Identification of related DNA sequences in Borrelia burgdorferi and two strains of Leptospira interrogans by using polymerase chain reaction.
The suitability of a polymerase chain reaction assay for Borrelia burgdorferi in epidemiological studies of infected tick populations was evaluated by using 28 strains of Leptospira interrogans and lysates of fixed adult Ixodes tick tissues. Two false positives representing leptospires were differentiated from B. burgdorferi by using an oligonucleotide probe.
Animals↗
Abdominal sparganosis in Ecuador: a case report.
Sparganosis, infection with plerocercoids of the pseudophyllidean tapeworm Spirometra, rarely has been described in Ecuador. We report the details of a human case of sparganosis identified serendipitously in the course of an abdominal hernia repair. The parasite was found moving freely upon the external oblique fascia adjacent to the site of a direct abdominal hernia. The organism was recovered intact, photographed while alive and preserved for subsequent detailed morphological studies. The presumed route of entry into this patient was percutaneous, after application of a poultice of snake flesh to the site of a painful abdominal hernia. The literature on sparganosis in South America is reviewed. This is the second case of human sparganosis reported from Ecuador.
Abdominal Muscles↗
Surface area calculation for Onchocerca volvulus microfilariae.
The pathogenesis of tissue damage in filarial infections involves the generation of inflammatory mediators by interaction of parasite surfaces with the host immune response. In the presence of a heavy parasite burden, the tremendous potential for development of adverse local or systemic inflammatory responses may be appreciated by knowledge of the cumulative surface area represented by circulating microfilariae. The approximate surface area of a single microfilariae of Onchocerca volvulus was calculated using mathematical formulae for standard geometrical shapes and values derived from serial measurements of electron micrographs. Numerical values for the surface area represented by large numbers of microfilariae are given and compared to surface areas of the host which can harbor many millions of microfilariae.
Animals↗
Onchocerca volvulus recombinant antigen: physical characterization and clinical correlates with serum reactivity.
An Onchocerca volvulus cDNA clone expressing epitopes found in adult and larval parasites, designated lambda RAL-2, was derived from a 1,000-base message present in adult O. volvulus, which encodes a protein with an apparent molecular weight of 17,000. This protein does not appear to be extensively posttranslationally modified. Serum samples from 52 individuals exposed to O. volvulus were examined for antibodies recognizing the lambda RAL-2 recombinant antigen; 77% produced such antibodies. In addition, individuals producing antibodies recognizing the recombinant antigen were significantly less likely to develop some aspects of ocular pathology associated with O. volvulus infection than were individuals who did not do so. These results suggest that recombinant antigens such as that produced by lambda RAL-2 may be useful in attempts to understand the mechanism of O. volvulus-induced ocular pathology.
Adult↗
Cell adherence to microfilariae of Onchocerca volvulus: a comparative study.
The conditions were examined for in vitro antibody-mediated adherence of granulocytes to microfilariae of Onchocera volvulus and Dirofilaria immitis. Reactivity in human sera from patients in endemic foci in Sudan was specific for O. volvulus and no reactions were observed with heterologous Onchocerca species or with Mansonella perstans. Microfilariae from skin, nodules or adult female worms were satisfactory targets for cell adherence, and the cells involved were almost exclusively eosinophils. The reaction was inhibited by indomethacin but not by nordihydroguaiaretic acid, an inhibitor of leukotriene production. Agents that slowed or stopped microfilarial motility (e.g. nifedipine, lidocaine, chloroquine) inhibited the reaction, probably by reducing target/cell contact. Ivermectin did not enhance the reaction, and in the absence of cells exerted only slight effects on the movement of microfilariae at higher concentrations (greater than 10 micrograms/ml). Antibody activity was labile, and did not persist well through freeze-thaw cycles. Some differences between homologous and heterologous mixtures (microfilariae/cells/serum) were seen but they could not be resolved satisfactorily. There were no apparent geographical differences between microfilariae from different foci in Sudan. In the D. immitis system neutrophils were the dominant cell type adhering to microfilariae, and the activity was stable to storage and freeze-thaw. No enhancement was detectable with diethylcarbamazine. Antibody activity was absorbable with microfilarial antigens and was reduced by agents that inhibited microfilarial motility. In dogs, adherence-mediating antibody was seen only in amicrofilaraemic animals with occult infection, and in only a minority of these sera. In humans the relationship to clinical findings was less clear, but patients with punctate keratitis were the most likely to have positive serum and were the most reactive in the assay. This system may therefore offer some insights into disease mechanisms in vivo, and its molecular mechanisms deserve further characterization.
Animals↗
Severe onchocercal dermatitis in the Ethiopian border region of Sudan.
Onchocerca volvulus infection of the residents of two villages in the Upper Atbara River region of Sudan (63.4% prevalence) was found to be medically and socially significant with a remarkable degree of pruritus and dermal pathology present. The severest skin changes, which were often confined to certain areas of the body, were most common in the teenage group (13-19 years). Quantitation of the clinical changes showed that the most severe alterations were present in patients with the lower levels of microfilariae in the skin (0.1-6 mf mg-1) rather than in those with higher levels. Nodules containing adult O. volvulus were found in many individuals, and often in clusters in older patients. Major losses of vision due to O. volvulus were not found, although microfilariae were frequently seen in the cornea and anterior chamber. The commonest corneal change was punctate keratitis, and this was most frequently seen in the teenage group. Trachomatous changes of eyelids and corneas were also seen. The prevalence values of O. volvulus infection in the two villages were significantly increased when, in addition to microfilarial presence in skin biopsies, onchocercal signs such as punctate keratitis, nodule presence and microfilariae in the anterior chamber were taken into consideration. This illustrates the need to consider factors other than skin snip parasitology in obtaining a diagnosis. This study also emphasizes the degree of severity that onchodermatitis can reach and that low levels of dermal microfilariae can be accompanied by very extensive skin changes without any loss of vision. The necessity of considering the severity of skin changes when defining tolerable levels of onchocerciasis in a community is discussed.
Adolescent↗
Molecular epidemiology of OHIO-1 beta-lactamase.
A total of 31 plasmids, all bearing a gene that encodes a novel, plasmid-mediated Richmond-Sykes class III beta-lactamase designated OHIO-1 and a gene that encodes aminoglycoside 2"-adenyltransferase, have been collected from hospitals in Ohio. By using restriction endonuclease digestion and Southern hybridization, we were able to demonstrate that all these plasmids have a common genetic origin.
Bacteria↗
Novel plasmid-mediated beta-lactamase in members of the family Enterobacteriaceae from Ohio.
Epidemiologic studies of plasmid-mediated resistance at the Cleveland Veterans Administration Medical Center revealed that related plasmids had disseminated among members of the family Enterobacteriaceae. We studied the beta-lactamases encoded by these plasmids in Escherichia coli C600 transformants or transconjugants. Substrate and inhibition profiles of the enzymes determined by two of these plasmids suggested an activity resembling TEM-1; however, isoelectric focusing revealed a pI of 7.0. These two plasmids were originally found in a Serratia marcescens (pDS076) and an Enterobacter cloacae (pDS075) strain isolated from the same sink in the medical intensive care unit and later, in an Enterobacter cloacae (pDS142 identical to pDS076) isolate colonizing a patient in the same unit. The plasmids also carried the aminoglycoside resistance determinant, 2"-aminoglycoside nucleotidyl transferase. A 2-kilobase AvaI restriction endonuclease digestion fragment of pSD075 known to carry the beta-lactamase determinant was used as a molecular probe. This probe did not recognize sequences of any plasmid-mediated beta-lactamase tested including the recently described determinants ROB-1, TLE-1, and OXA-4-7. A TEM-1 probe derived from the 0.7-kilobase PstI-EcoRI fragment of pBR322 failed to recognize the new beta-lactamase gene. Four additional Enterobacter cloacae and two Enterobacter aerogenes strains isolated in Columbus, Ohio, have been shown to produce a pI 7.0 beta-lactamase and to carry plasmids recognized by the 2-kilobase probe. These data suggest dissemination of a novel plasmid-mediated beta-lactamase among members of the family Enterobacteriaceae in Ohio and demonstrate the development and utility of a molecular probe for the new determinant. We suggest that the novel beta-lactamase be named OHIO-1.
DNA, Bacterial↗
Clonorchiasis and praziquantel.
Explore the source record for details and available documents.
Clonorchiasis↗
Pentamidine: a review.
Pentamidine, recently released for clinical use, is effective in therapy for the hemolymphatic stage of Gambian trypanosomiasis, antimony-resistant leishmaniasis, and Pneumocystis carinii pneumonia. The mechanism of action is unclear and may differ for different organisms. Trypanosomes actively transport pentamidine intracellularly, and the drug may then interfere with DNA biosynthetics. However, pentamidine appears to kill nonreplicating P. carinii. The mechanism of killing is unexplained. The pharmacokinetics of pentamidine has been incompletely studied in humans. The estimated volume of distribution is 3 liters/kg. Levels in plasma of pentamidine range from 0.3-1.4 microgram/ml after standard 4 mg/kg dosing, with no appreciable increase in drug levels on successive dosing and no correlation between levels and creatinine clearance or adverse reactions. The drug appears to be concentrated in the kidney and excreted in the urine, with levels detectable six to eight weeks after cessation of therapy. Immediate adverse reactions have included hypotension, nausea, and vomiting. Local pain or abscess formation at an injection site, mild azotemia, leukopenia, abnormal findings from liver function tests, and hypoglycemia may also occur.
Amidines↗