Biomedical subjects

J L Fox

Publications and source records attributed to J L Fox.

At least 235 records · Page 13Linked to original sources

PubMed1985

Chemical synthesis of a gene encoding the human complement fragment C5a and its expression in Escherichia coli.

A gene coding for the C5a fragment of the fifth component of human complement has been chemically synthesized, cloned, and expressed in Escherichia coli. The 253-base-pair gene fragment was built through a two-step enzymic assembly of 16 oligonucleotides, the average length of each being 32 residues. The oligonucleotides were synthesized by using the phosphoramidite method. The gene was cloned in a pBR322-derivative plasmid downstream from the lac up-promoter mutant, UV5-D. The expression of C5a was detected and measured by immunoassay and a radioligand binding assay. C5a from E. coli was comparable to C5a purified from human serum in inhibiting binding of human 125I-labeled C5a to its putative receptor on polymorphonuclear leukocytes. Studies of smooth muscle contraction in isolated guinea pig ileum showed that the recombinant C5a was biologically active and produced cross-tachyphylaxis with human serum-derived C5a. The results demonstrate the feasibility of expressing C5a anaphylatoxin in bacteria and provide a system for mutagenesis of the C5a protein.

Animals↗

PubMed1985

Evidence for unpredicted transmembrane domains in acetylcholine receptor subunits.

Two monoclonal antibodies (mAbs 236 and 237) against a synthetic peptide composed of the same amino acid residues as the sequence 152-167 of the alpha subunit of the acetylcholine receptor were obtained, and their crossreaction with the synthetic peptide, alpha subunit, and solubilized receptor was demonstrated. Crossreaction with the synthetic peptide alpha 159-169 was less by a factor of 10(4), suggesting that the mAbs bind primarily to the sequence alpha 152-159. Cholinergic ligands did not inhibit mAb binding. No crossreaction was observed with the receptor in native membranes, but the mAbs could bind to receptor reconstituted into liposomes in which 50% of the receptors have their cytoplasmic surface oriented outside. When native membranes were permeabilized with saponin, mAbs directed against cytoplasmic determinants of the receptor could bind to them, but mAbs 236 and 237 could not. However, after treatments that removed peripheral proteins from the cytoplasmic surface, binding of both mAbs was observed. Further evidence for the cytoplasmic localization of this sequence was provided by observation of partial competition for binding between mAbs 236 and 237 and mAbs previously demonstrated to bind to the cytoplasmic surface of the receptor. To account for these findings, a model for the organization of the polypeptide chains in receptor subunits is proposed that has a total of seven transmembrane domains in each subunit, two of which are amphipathic and one of which is not alpha-helical.

Amino Acid Sequence↗

PubMed1985

Reduced epidermal Langerhans cell densities in patients with pulmonary malignancies do not correlate with anergy or nutritional status.

Epidermal Langerhans cell (ELC) densities are markedly reduced in a number of clinical situations including anergic sarcoidosis patients. To help determine whether this reduction is related to the anergic or nutritional status of the patient, we examined the non-sun-exposed epidermis of 23 hospitalized patients with various malignancies (MP), 10 hospitalized control (HC) patients without malignancy, and 24 biopsies from historical control (HIC) patients. There was no significant difference in the density of HLA-DR+ ELC among HC, HIC, or patients with nonpulmonary malignancy (primary or metastatic). Six patients with pulmonary malignancy had significantly fewer HLA-DR+ and OKT6+ epidermal cells. The reason ELC densities are reduced specifically in pulmonary malignancies remains under study.

Adult↗

PubMed1985

Human T-cell lymphotropic virus type III: immunologic characterization and primary structure analysis of the major internal protein, p24.

The major internal structural protein of human T-cell lymphotropic virus type III (HTLV-III), a virus etiologically implicated in acquired immunodeficiency syndrome (AIDS), was purified to homogeneity. This 24,000-molecular-weight protein (p24) was shown to lack immunologic cross-reacting antigenic determinants shared by other known retroviruses, including HTLV-I and HTLV-II, with the exception of equine infectious anemia virus (EIAV). A broadly reactive competition immunoassay was developed in which antiserum to EIAV was used to precipitate 125I-labeled HTLV-III p24. Although the major structural proteins of HTLV-III and EIAV competed in this assay, other type B, C, and D retroviral proteins lacked detectable reactivity. Thus, HTLV-III is more related to EIAV than to any other retroviruses. That the HTLV-III isolate is very distinct from HTLV-I and HTLV-II was further confirmed by the amino acid compositions of the major internal antigens of all three isolates. Moreover, comparison of the amino-terminal amino acid sequence of HTLV-III p24 with analogous sequences for HTLV-I and HTLV-II p24 showed that these proteins do not share significant sequence homology. In an attempt to evaluate immune response in individuals exposed to HTLV-III, sera from AIDS and lymphadenopathy syndrome patients as well as from clinically normal blood donor controls were tested for antibodies to HTLV-III p24. The results showed that sera from 93% of lymphadenopathy syndrome patients and 73% of AIDS patients exhibited high-titered antibodies to HTLV-III p24. In contrast, none of the normal control sera showed detectable reactivity to HTLV-III p24.

Acquired Immunodeficiency Syndrome↗

PubMed1985

The empty sella: air-enhanced CT.

Two patients who had histories of allergy to iodine compounds underwent air-enhanced CT of the sellar cisterns. In both patients, the basal cisterns and empty sella were well demonstrated. The technique, results of which compared favorably with those of metrizamide cisternography, is described.

Empty Sella Syndrome↗

PubMed1985

Microsurgical removal of suprasellar meningiomas.

The authors report 17 cases of large suprasellar meningiomas operated on during the 2-year period from February 1982 through March 1984. The tumors ranged from 4 to 9 cm in diameter. These patients presented with severe visual loss (4 were blind) and optic atrophy or papilledema. These tumors were noteworthy in their encroachment against and around the carotid arteries and optic nerves laterally, as well as against the hypothalamus with extension into the interpeduncular cistern and frontal fossa. Advanced microsurgical technique assisted in total removal of all tumor tissue with preservation of vital structures. There were three deaths: two from pulmonary embolism and one from gastrointestinal hemorrhage. The surgical technique for the total removal of these very large tumors is described.

Adult↗

PubMed1985

Microsurgery for giant craniopharyngiomas in children.

The authors report 20 cases of giant craniopharyngioma in children operated on during the 6-year period from 1978 through 1984. The tumor size (maximal diameter) ranged from 5 to 11 cm. These patients presented with increased intracranial pressure, severe visual loss, and neurological and endocrinological deficits. Tumor growth had occurred in several directions, causing displacement of the circle of Willis, the optic apparatus, and the hypothalamus, as well as encroachment into the interpeduncular and prepontine cisterns and into the frontal, temporal, and posterior fossae. The surgical technique for total removal of these giant tumors in the last 10 cases is described. Emphasis is placed on the use of microsurgical technique during the first operation, close endocrinological follow-up, and early reevaluation by computed tomographic scanning.

Adolescent↗

PubMed1984