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Biomedical subjects

J McKerrow

Publications and source records attributed to J McKerrow.

8 recordsLinked to original sources
PubMed1992

Primary pulmonary hypertension and human immunodeficiency virus infection in a non-hemophiliac man.

We describe clinical and postmortem findings in a 44-year-old man with pulmonary hypertension and infection with the human immunodeficiency virus (HIV-1). Plexogenic angiopathy and veno-occlusive lesions were present, in addition to a mild, patchy pulmonary interstitial lymphoid infiltrate. The clinical data for 14 previously reported cases of HIV-associated primary pulmonary hypertension are summarized. We speculate that these vascular changes may be due to damage from a specific immune response to HIV.

Adult↗
PubMed1990

Purification and amino-terminal sequence analysis of the complement-fixing and precipitin antigens from Coccidioides immitis.

Two proteins (21 and 48 kilodaltons) purified from endospore-spherule culture filtrates of Coccidioides immitis are identified as precipitin and complement-fixing antigens, respectively. To allow specific structural comparison to antigens identified by other investigators and as a first step to eventual serodiagnostic antigen production by recombinant DNA technology, amino-terminal amino acid sequences were determined for these antigens.

Amino Acid Sequence↗
PubMed1987

Molecular cloning of Schistosoma mansoni myosin.

A cDNA library representative of adult Schistosoma mansoni mRNA populations was screened with serum from infected rats (refractory hosts), positive plaques being rescreened with serum from infected mice and humans. Based on general reactivity, one clone was selected for further study. As judged by immunofluorescence data, size of corresponding mRNA, and nucleotide sequence analysis, the recombinant expresses approximately 625 amino acids of a schistosome muscle myosin rod. Antibodies evoked by the protein do not cross-react with human cardiac or skeletal muscle, are not invariably stimulated in naturally infected human beings, and rise in titer after chemotherapeutic cure, findings which suggest that the antigen is not a causative agent of Katayama fever, and is probably presented by degenerating worms. The schistosome sarcomeric myosin gene, the most primitive examined to date, appears to be unique inasmuch as it may not be a member of a multigene family and encodes a single mRNA transcript; nonetheless, predicted higher order structure of its translation product is consistent with expected function.

Amino Acid Sequence↗
PubMed1987

Schistosome elastases: biological importance, structure, function and stage-specific expression.

Larval schistosomes (Digenea: Trematoda) invade their definitive host by directly penetrating the skin. During the process they secrete a number of macromolecules, ostensibly to facilitate their entry. Among these we have identified and characterized a dominant proteolytic species: a serine protease capable of fragmenting keratin, types IV and VIII collagen, proteoglycan, fibronectin, laminin, and elastin. The enzyme exhibits the specificity characteristic of elastases, has a molecular mass of 30,000 Da and pI of 7.8, and is potently immunogenic in its native form. Specificity of the active site has been analysed, tetrapeptides having large hydrophobic or aromatic amino acids at size P1 serving as best substrates. The amino terminal 20 amino acids of the mature enzyme have been sequenced and the information derived has been used to construct an oligonucleotide (22-mer) complement of its corresponding mRNA. The latter has been used to establish, by Northern analysis, that expression of the enzyme is stage specific (differing in this respect from most schistosome immunogens), and under transcriptional control. Transcripts are encoded by a multigene family. Several cDNAs hybridizing to the oligonucleotide have been isolated, subcloned into bacteriophage M-13, and sequenced by the di-deoxy method. It is our expectation that this line of investigation will lead towards: (i) an anti-infection vaccine; (ii) a means for chemically preventing infection (using enzyme inhibitors), and/or (iii) a rapid diagnostic assay of prepatent infection.

Amino Acid Sequence↗
PubMed1986

Schistosoma mansoni: purification and characterization of the major acidic proteinase from adult worms.

We report purification of the major digestive proteinase from adult worms of Schistosoma mansoni. This enzyme is a thiol proteinase with a pH optimum of 5 and is activated by thiol reagents. It was purified 300-fold using a combination of gel chromatography and chromatofocusing. It readily hydrolyzed hemoglobin with an apparent Km of 0.29 microM and a specific activity of 27 micrograms degraded/min/mg enzyme at 37 C. Peptides with positively charged amino acids were preferentially cleaved. The enzyme degraded Boc-Arg-Arg-7-amino-4-methyl coumarin with a kcat/Km of 9083 M-1 sec-1. Lengthening the peptide chain to 3 amino acids or substituting glycine for the amino terminal arginine resulted in decreased activity. The enzyme was inhibited by chloromethylketone-derivatized peptides of similar sequence and by leupeptin. The purified proteinase exhibits microheterogeneity in different preparations with forms ranging in molecular weight from 30,000 to 35,000, and pI 5.7-6.0.

Animals↗
PubMed1984

Hepatic cirrhosis: magnetic resonance imaging.

The effect of periportal collagen deposition on magnetic resonance images and T1 and T2 relaxation times was studied in the rat. Hepatic cirrhosis was induced in 29 rats by chronic intraperitoneal thioacetamide injections. Another 14 rats in which liver abnormalities did not develop were used as controls. The rats were imaged using a small-bore resistive magnet. Histologic correlations and hydroxyproline measurements were performed to document the changes in periportal collagen deposition. The T1 and T2 relaxation times, determined both in vivo and in vitro with spectroscopy, were compared between the normal group and the group with moderate to severe histologic evidence of cirrhosis. The deposition of two to four times the normal amount of collagen in the liver did not affect the T1 or T2 relaxation time. Relatively pure periportal collagen fibrosis does not appear to affect the magnetic resonance image or T1 or T2 relaxation times of the rat liver.

Animals↗
PubMed1983

The epidermal barrier to Schistosoma mansoni infection.

The stratified epithelium serves as protection for underlying tissues and organs, and the structural fitness of the epidermal cells has been extensively reported. We studied the possible roles played by the epidermis as a barrier against the migration of Schistosoma mansoni larvae. Freshly shed cercariae were collected and placed on the back skin of 2-day-old rats. Electron microscopy of biopsies taken at various intervals showed the larvae and their secretory granules in keratinocytes in which the cytoplasm had become homogeneous in appearance. SDS gel electrophoresis showed the digestion of purified epidermal keratin (60K protein) by a proteinase secreted from cercariae, but this activity was inhibited by an inhibitor purified from epidermal cells. These findings suggest that epidermal cells function both structurally and chemically as a barrier against cercariae invasion.

Animals↗