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Biomedical subjects

P Cameron

Publications and source records attributed to P Cameron.

At least 19 recordsLinked to original sources
PubMed1992

Production, purification and characterization of canine prostromelysin.

One of the best studied animal models of osteoarthritis is a dog model in which the anterior cruciate ligament of the hind limb stifle joint is transected (Pond-Nuki model). To determine whether stromelysin might play a role in this model, it was necessary to purify the enzyme for production of suitable probes. In the present study, dog synovial fibroblasts were stimulated to express a metalloproteinase that was demonstrated to be canine prostromelysin by Northern blot, protein purification and amino-terminal sequence analyses. Unlike rabbit synoviocytes, passaged dog synoviocytes did not express stromelysin mRNA in response to recombinant human IL-1, but expressed stromelysin mRNA only upon treatment with dog monocyte-conditioned medium (dMCM). The aminophenylmercuric acetate (APMA)-activatable metalloproteinase present in the culture supernatants of stimulated dog synoviocytes was purified using a combination of ion-exchange and dye matrix affinity chromatography. The purified canine metalloproteinase co-migrated on reducing SDS-PAGE with recombinant human prostromelysin-1 as a doublet with apparent molecular masses of 54 and 56 kDa. Similar to APMA-activated human prostromelysin-1, the APMA-activated canine metalloproteinase was inhibited by 1,10-phenanthroline or recombinant human tissue inhibitor of metalloproteinase (TIMP). The amino-terminal sequences of the canine pro- and APMA-activated enzymes were compared with those of human, rabbit and rat stromelysin. The striking homologies among the sequences demonstrated that the purified canine metalloproteinase was indeed canine prostromelysin. A rabbit anti-canine prostromelysin polyclonal antiserum was generated and used to localize the enzyme within cultured dog synoviocytes and articular cartilage stimulated with dMCM. The reagents developed in this study should be useful for examining the expression and distribution of prostromelysin in canine models of osteoarthritis.

Amino Acid Sequence↗
PubMed1991

AIDS--intervention works; "education" is questionable.

A decrease in or leveling off of new cases of transfusion-related AIDS coupled with continued increases in homosexual and IV drug cases suggests that intervention by barring contaminated blood has worked and "education" has worked less well, if at all. Current evidence suggests that the blood-bar resulted in the change in new AIDS cases among children within 3 years and among adults within 3 1/2 years.

Acquired Immunodeficiency Syndrome↗
PubMed1991

The distribution of synapsin I and synaptophysin in hippocampal neurons developing in culture.

As a first step toward elucidating mechanisms involved in the sorting of synaptic vesicle proteins in neurons, we have used immunofluorescence microscopy to determine the distribution of two synaptic vesicle proteins, synapsin I and synaptophysin, in hippocampal neurons developing in culture. In mature cultures, synapsin I and synaptophysin immunoreactivity was concentrated in puncta that were restricted to sites where axons contacted neuronal cell bodies or dendrites. Electron-microscopic immunocytochemistry demonstrated that these puncta corresponded to vesicle-filled axonal varicosities that were exclusively presynaptic. At early stages of development, before cell-cell contact, both synapsin I and synaptophysin were preferentially localized in axons, where they were particularly concentrated in the distal axon and growth cone. In axons that did not contact other cells, immunostaining for these two proteins had a granular appearance, which persisted for at least 7 d, but focal accumulations of vesicles comparable to those seen at sites of synaptic contact were not observed. When neurons contacted one another, numerous puncta of synapsin I and synaptophysin formed within the first week in culture. Double-label immunofluorescence demonstrated that the two vesicle antigens were closely codistributed throughout these stages of development. These observations demonstrate that synaptic vesicle proteins assume a polarized distribution within nerve cells beginning early in development, as soon as the axon can be identified. In contrast, differences in microtubule polarity orientation that distinguish mature axons and dendrites, and that have been proposed to account for the selective sorting of some materials in nerve cells, first appear at a subsequent stage of development. The selective distribution of synaptic vesicle proteins to the axon occurs in isolated cells, independent of interactions with other cells. In contrast, the formation of large clusters of vesicles typical of presynaptic specializations requires contact with an appropriate postsynaptic target. Thus, in cultured hippocampal neurons, the localization of synaptic vesicles in presynaptic specializations is the result of sorting mechanisms intrinsic to individual neurons as well as to mechanisms mediated by cell-cell contact.

Animals↗
PubMed1989

Identification of a monocyte specific pre-interleukin 1 beta convertase activity.

Interleukin 1 (IL-1) is a lymphokine secreted by monocytes in response to a variety of inflammatory stimuli. IL-1 beta, the predominant form of IL-1 produced by human monocytes, is synthesized as an inactive precursor of 31 kDa and is cleaved at Asp116-Ala117 to yield a 17.5-kDa extracellular form. The exact cellular site of cleavage and mechanism of secretion is at present unknown. We have prepared cell-free postnuclear extracts from freshly isolated human monocytes as well as THP.1 cells, a human monocyte-like cell line, and various blood lymphocytes and fibroblast cell lines. Using pre-IL-1 beta synthesized by in vitro transcription and translation, we have shown that only extracts derived from human monocytes and THP.1 cells were capable of cleaving precursor IL-1 beta to authentic mature IL-1 beta. Subcellular fractionation of the extracts suggested that the processing activity is found in the cytosol of monocytes or monocyte-like cell lines. The cleavage product of this protease is identical to authentic IL-1 beta as shown by mobility on SDS/PAGE and amino acid sequence analysis of the [3H]leucine-labeled product. The cleavage product is also capable of binding to the IL-1 receptor found on fibroblast membranes. Finally, mutation of Asp116----Ala116 rendered the IL-1 beta precursor resistant to cleavage by the processing activity. We conclude that a protease activity found only in monocytes will specifically process IL-1 beta to an active form.

Caspase 1↗
PubMed1989

Effect of homosexuality upon public health and social order.

Are homosexuals "not dangers to society" and is homosexuality "compatible with full health"? To answer these questions 4,340 adult respondents drawn via area probability sampling from 5 metropolitan areas of the USA self-administered an extensive sexuality/public order questionnaire of over 500 items. Bisexuals and homosexuals (about 4% of the sample) as compared to heterosexuals: (1) more frequently exposed themselves to biological hazards (e.g., sadomasochism, fisting, bestiality, ingestion of feces); (2) exposed themselves sexually to more different bodies (e.g., more frequently admitted to participating in orgies, reported considerably larger numbers of sexual partners); (3) more frequently reported participating in socially disruptive sex (e.g., deliberate infection of others, cheating in marriage, making obscene phone calls); and (4) more frequently reported engaging in socially disruptive activities (e.g., criminality, shoplifting, tax cheating). From the standpoints of individual health, public health and social order, participating in homosexual activity could be viewed as dangerous to society and incompatible with full health.

Adult↗
PubMed1989

Enhanced recency effects with changing-state and primary-linguistic stimuli.

A number of explanations for the modality effect in immediate serial recall have been proposed. The auditory advantage for recall of recency items has been explained in terms of (1) the contributions of precategorical acoustic storage (PAS), (2) an advantage of changing-state over static stimuli, and (3) an advantage of primary-linguistic coding. Four experiments were conducted to evaluate these hypotheses. In the first, subjects viewed seven consecutive rectangles of different colors on a computer monitor. A small recency effect was obtained when the task was to recall the colors of the rectangles in order, with the size of the effect being independent of whether the rectangles remained stationary on the screen or moved in one of four directions. However, when the task was to recall the direction of movement of the rectangles, a larger recency effect was found. This pattern of results was interpreted as suggesting that recency effects are enhanced by changing-state stimulus information, but only when the changing-state information serves to identify the stimulus. Experiments 2 and 3 provided converging evidence by demonstrating an analogous recency advantage for changing-state visual stimuli that were somewhat different from those of Experiment 1. Experiment 4 demonstrated recency effects with synthesized speech stimuli that were substantially greater than were those found with the changing-state visual stimuli of the first three experiments. Implications of the results for the PAS, changing-state, and primary-linguistic hypotheses, as well as temporal-distinctiveness theories of recency, are discussed.

Color Perception↗
PubMed1986

Antibodies of predetermined specificity to the major charged species of human interleukin 1.

The development of highly specific antisera to human interleukin 1 (IL-1) has been an elusive goal hampered mainly by the availability of only limited amounts of pure immunogen. To surmount this difficulty, three peptides of the major charged species of IL-1 (pI 6.8) were synthesized and covalently coupled to keyhole limpet hemocyanin (KLH). All three peptide-KLH conjugates raised rabbit heterologous antisera that bound intact pure IL-1 in a dose-dependent and domain-specific manner. Immunoblot analysis of crude concentrated culture supernatants with these antisera showed each of them to be highly specific for mature 18-kDa IL-1. Immunoblot analysis of monocyte lysates revealed a single 33-kDa band consistent with the size of the IL-1 precursor molecule deduced from cloned cDNA. These reagents should prove to be valuable tools in the localization and measurement of IL-1 in cells and fluids and may permit the separate study of individual IL-1 species as well as discrete domains of intact IL-1 molecules.

Animals↗
PubMed1986

Psychiatric training and the trainee: is there a fit?

This data would suggest that psychiatric training programs may not be organized according to the interest or needs of many trainees. The emphasis on fulltime research in neurobiological psychiatry is centre stage in most programs, and yet according to our survey, few residents view this as a desirable career path. Our data from 8 years of trainees at the University of Toronto indicates that a new model of training streams would best suit the needs of the trainee, the profession and the community. This report is a continuation of a study into the recruitment process. An earlier report was published in the Canadian Journal of Psychiatry Vol. 29, December 1984. Our present data is on two groups of trainees as well as from faculty.

Canada↗
PubMed1985

Amino acid sequence analysis of human interleukin 1 (IL-1). Evidence for biochemically distinct forms of IL-1.

The pI-6.8 species of normal human interleukin 1 (IL-1) has been isolated by ion-exchange and reverse-phase high-performance liquid chromatography. The isolated material had a molecular weight of 18,000, and had a specific bioactivity of 1.7 X 10(7) half-maximal U/mg in the murine thymocyte proliferation assay, values similar to those obtained for murine P388D1-derived IL-1 (12), and human IL-1 isolated by a previously published purification protocol (15). Amino-terminal sequence analysis revealed a single N-terminal, and resulted in the identification of 30 of the first 35 amino acid residues. Sequence of three CNBr cleavage fragments of purified IL-1 resulted in the identification of an additional 38 residues. All of the sequences agree exactly with those deduced from complementary DNA (cDNA) by Auron, et al. (18), demonstrating that this cloned cDNA, though considerably different from the cDNA reported for murine IL-1 (12), nevertheless codes for the pI-6.8 species of human IL-1. The evidence also shows that the precursor protein for human IL-1 is largely processed at the N-terminal end. Little or no processing occurs at the carboxy-terminal end. Sequence homology with interferon-inducing factor (26) suggests that the pI-6.8 species of human IL-1 is a member of a gene family. Although equally potent in the murine thymocyte proliferation assay, murine IL-1 and the pI-6.8 species of human IL-1 are structurally distinct. Further study will answer the interesting question as to the relationship of the other charged species of human IL-1 to these distinct IL-1 classes.

Amino Acid Sequence↗