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Biomedical subjects

S J Martin

Publications and source records attributed to S J Martin.

At least 19 recordsLinked to original sources
PubMed1992

Characterization of neutralizing antibodies to bovine enterovirus elicited by synthetic peptides.

Six synthetic peptides corresponding to regions of bovine enterovirus (BEV), strain VG-5-27, elicited antibodies in mice which reacted with the virus in various assays. These antibodies have been characterised on the basis of their ability to (1) neutralize the virus, (2) bind to the intact virus particle in an immunoprecipitation test, (3) react with the denatured viral proteins, and (4) give immunofluorescent staining of virus infected cells. We have also determined the proportion of antipeptide antibody which binds to the virus in each case. All of the sera immunoprecipitated the virus and neutralized its activity to varying extents. Two of the sera specific for VP 1 sequences failed to react with denatured VP 1 whereas all the other antisera reacted with their respective parental proteins. All of the sera reacted with VG-5-27 infected cells in an immunofluorescence test. The proportion of antibodies to each peptide recognizing intact virus was variable and did not appear to correlate with neutralizing activity. In addition, the ability of each of the sera to react with and neutralize three other strains of the virus was analysed. With one of these strains significant cross-neutralization was observed.

Amino Acid Sequence↗
PubMed1992

Suicide and lunar cycles: a critical review over 28 years.

20 studies which have examined the relations between completed suicide or attempted suicide and suicide threats with the synodic lunar cycle are reviewed. Most studies indicated no relation between lunar phase and the measures of suicide. The positive findings conflicted, have not been replicated, or were confounded with variables such as season, weekday, weather, or holidays. It is concluded that there is insufficient evidence for assuming a relationship between the synodic lunar cycle and completed or attempted suicide.

Canada↗
PubMed1991

Lymphocyte transformation abnormalities in bovine immunodeficiency-like virus infected calves.

Bovine immunodeficiency-like virus (BIV) is a lentiviral pathogen of cattle which is genetically and antigenically related to the human immunodeficiency virus (HIV-1). To determine the impact of BIV infection on the bovine immune system we studied the lymphocyte transformation responses of male Holstein calves inoculated with BIV strain R-29 to three mitogens: pokeweed mitogen (PWM), concanavalin A (Con A), and phytohemagglutinin (PHA) at two and six months post-infection. By six months post-inoculation the response to all three mitogens was diminished compared to control animals and remained depressed 10 months post-inoculation. These results demonstrate that a functional impairment of lymphocytes can be observed early in the course of BIV infection, and prior to the onset of overt clinical disease.

Animals↗
PubMed1991

Ultraviolet B irradiation of human leukaemia HL-60 cells in vitro induces apoptosis.

UV radiation is known to be a potent agent for the induction of programmed cell death (apoptosis) in human skin. However, the mechanistic aspects of UV-induced apoptosis remain ill-defined. In this study the effects of varying periods of UV-irradiation on the human leukaemia HL-60 cell line and on five other human cell lines were investigated. HL-60 cells were found to rapidly undergo apoptosis en masse after short periods of UV-irradiation, whereas prolonged exposure of these cells to this form of radiation induced a more rapid form of cell death which was suggestive of necrosis, the pathological mode of cell death. Similar effects were observed on the U937 (myelomonocytic), Molt-4 (T-lymphoblastoid), and Molt-3 (T-lymphoblastoid) cell lines, whereas the K562 (pre-erythroid) and Daudi (B-lymphoblastoid) cell lines proved to be relatively resistant to the death-inducing properties of UV-irradiation by comparison. UV-induced apoptosis in cell lines was characterized by morphological changes as well as DNA fragmentation into unit multiples of approximately 200 bp, which was indicative of endogenous endonuclease activation. This DNA fragmentation pattern was not detected in cells immediately after UV-irradiation, and was therefore not the result of direct UV-induced DNA damage. UV-induced apoptosis of the HL-60 cell line was found to require extracellular calcium and to be inhibited in a dose-dependent way by zinc added to the culture medium.

Calcium↗
PubMed1991

Dose-dependent induction of apoptosis in human tumour cell lines by widely diverging stimuli.

Cell death may occur by either of two mechanisms: apoptosis or necrosis. Necrosis, the first type of cell death to be recognized, is an uncontrolled degenerative phenomenon invariably caused by noxious stimuli and is the result of irreversible failure of membrane function. Apoptosis, on the other hand, is a death process which involves a series of well-organized events which require active cell participation, and is primarily caused by physiological stimuli. In the present study we show that cell death induced by a range of varied agents may take the form of either apoptosis or necrosis. Apoptotic cell death was found to occur at low levels of these agents, while at higher levels necrosis occurred. Hence, cells which are not killed directly, but merely injured by these agents, have the capacity to activate an internally programmed suicide death mechanism, whereas cells receiving greater injuries apparently do not. In addition, the presence of extracellular calcium was found to be necessary for the induction of apoptosis with all agents tested.

Calcium↗
PubMed1991

Programmed cell death (apoptosis) in lymphoid and myeloid cell lines during zinc deficiency.

Three human cell lines of lymphoid (Molt-3 and Raji) or myeloid (HL-60) origin were maintained in vitro under zinc-sufficient or zinc-deficient conditions. Under these conditions, cell proliferation, viability and mode of death (apoptotic or necrotic) were assessed. All three cell types decreased their proliferative capacity and viability under conditions of zinc deficiency. Cell death in the HL-60 and Raji cultures occurred primarily via apoptosis, while most cells in zinc-deficient Molt-3 cultures died via necrosis. Apoptosis in zinc-deficient cultures of HL-60 and Raji cells was characterized by a slow decline in culture viability as cells with condensed and fragmented nuclear DNA appeared. These morphological changes were accompanied by an increase in cell buoyant density, which allowed separation of viable apoptotic cells from their non-apoptotic counterparts by means of percoll stepdensity gradients. Necrosis in zinc-deficient Molt-3 cultures was characterized by rapid loss of cell culture viability as these cells underwent direct lysis. Intact necrotic cells were easily identified by the flocculated state of their chromatin as well as the decreased basophilia of their cytoplasm. Analysis of DNA from apoptotic HL-60 and Raji cells revealed that internucleosomal DNA degradation, indicative of endogenous endonuclease activation, had occurred, whereas the nuclear DNA of necrotic Molt-3 cells remained relatively unfragmented. The different modes of cell death evoked may reflect the relative sensitivities of cells of these lineages to zinc levels in vivo.

Cell Division↗
PubMed1991

Identification of Vibrio vulnificus O serovars with antilipopolysaccharide monoclonal antibody.

A serotyping scheme for Vibrio vulnificus predicated on the detection of lipopolysaccharide (LPS) antigens is proposed. The serovar O typing scheme used to type V. vulnificus employs polyclonal antisera raised in rabbits immunized with heat-killed whole-cell vaccines. Polyclonal typing sera produced in this manner cross-react with heterologous strains. Affinity purification of polyclonal antisera with LPS affinity columns resolved some of these cross-reactions; however, affinity-purified polyclonal antisera still showed cross-reactions that were nonreciprocal. On the basis of the serological patterns that were obtained with affinity-purified polyclonal antisera, V. vulnificus strains were selected as vaccine strains for production of monoclonal antibody. Spleen cells harvested from BALB/c mice immunized with formalin-killed V. vulnificus cells were fused with SP2/O-Ag 14 myeloma cells. Hybridomas were screened by using LPS and whole-cell enzyme-linked immunosorbent assay to identify clones secreting LPS-specific antibodies. Monoclonal antibodies identified five LPS serological varieties of V. vulnificus and a single serovar each for Vibrio damsela and Vibrio hollisae. No cross-reactions between V. vulnificus and V. hollisae or V. damsela were observed.

Agglutination Tests↗
PubMed1991

Clinical evaluation of the use of decalcified freeze-dried bone allograft with guided tissue regeneration in the treatment of molar furcation invasions.

The purpose of this study is to evaluate the potential of decalcified freeze-dried bone allograft (DFDBA) combined with a barrier material in the treatment of human molar furcation defects (experimental) as compared to the barrier technique alone (control). Fifteen pairs of Class II or III furcation invasion defects comprised the study group. Measurements with calibrated periodontal probes were made to determine soft tissue recession, probing depth, and attachment levels. Defects from each pair were randomly selected to be treated with an expanded polytetrafluoroethylene membrane (e-PTFE) and DFDBA or the membrane alone. Additional measurements were made during surgery to determine crestal resorption, and vertical and horizontal open probing attachment. The membrane was removed 4 to 6 weeks post-insertion. Six months post-treatment, each site was surgically reentered and measurements repeated. Following either treatment, recession was minimal with statistically significant improvement in probing depth reduction and clinical attachment level gain favoring the combined technique. Hard tissue changes were comparable for alveolar crestal resorption, however, there was a distinct difference, statistically, for both horizontal and vertical bone repair favoring the use of the demineralized bone graft in combination with the e-PTFE membrane.

Bone Transplantation↗
PubMed1990

Induction of apoptosis (programmed cell death) in human leukemic HL-60 cells by inhibition of RNA or protein synthesis.

Apoptosis is regarded as a suicidal cell response since the dying cell appears to be an active participant. Previous studies have shown that apoptosis of various murine cell types, induced by a variety of stimuli, required RNA and/or protein synthesis. However, when human promyelocytic leukemia HL-60 cells were induced to undergo apoptosis by treatment with the calcium ionophore A23187 or microtubule-disrupting agents, in the presence of inhibitors of macromolecular synthesis, apoptosis of these cells was neither abrogated nor delayed. Furthermore, the presence of either cycloheximide, an inhibitor of protein synthesis, or actinomycin D, an RNA synthesis inhibitor, alone was found to induce large scale apoptosis of these cells. Apoptosis in these cells was characterized by cell and chromatin condensation followed by nuclear and DNA fragmentation. In common with many other studies, this DNA fragmentation was found to have an approximately 200-bp multiple pattern, which is consistent with the activation of an endogenous endonuclease which cleaves at internucleosomal sites. Calcium-dependent endonuclease activity of this type was also detected in the isolated nuclei of untreated HL-60 cells. The morphologic and biochemical changes characteristic of apoptosis were found to precede cell death, as measured by trypan blue uptake and were completely distinct from death caused by toxic stimuli such as azide, ethanol, or heat treatment. Similar experiments with six other human cell lines confirmed that this phenomenon was not peculiar to the HL-60 cell line. These results suggest that certain dividing cell populations do not require RNA or protein synthesis to undergo apoptosis and further, that continuous transcription and translation of some regulatory protein(s) may be required to maintain control over the apoptotic "machinery" of such cells.

Calcimycin↗
PubMed1990

Chemically synthesized peptides elicit neutralizing antibody to bovine enterovirus.

Synthetic peptides representing 14 regions of the bovine enterovirus structural proteins were used to raise antibodies in mice. The peptides were predicted using amino acid sequence alignments with the position of antigenic sites on other picornaviruses. Five of the anti-peptide antibodies reacted with the virus in an immunoprecipitation test. Furthermore, each of these anti-peptide antibodies neutralized virus infectivity; those directed against peptides of VP2 and VP3 neutralized to a greater extent than those directed against peptides of VP1. The positions of these epitopes in the viral structural proteins are discussed in relation to corresponding positions in other picornaviruses.

Amino Acid Sequence↗
PubMed1990

Disruption of microtubules induces an endogenous suicide pathway in human leukaemia HL-60 cells.

Terminally differentiated HL-60 cells undergoing programmed cell death (apoptosis) in culture were found to have a disrupted microtubular network. Treatment of undifferentiated HL-60 cells with microtubule-disrupting agents alone was found to induce apoptosis en masse in these cells. In contrast, disruption of microfilaments did not induce apoptosis; instead these cells underwent necrosis, the pathological mode of cell death. Apoptosis in response to microtubule disruption in HL-60 cells was characterized by cell shape changes, nuclear condensation followed by fragmentation and the separation of the cell into numerous intact fragments, termed apoptotic bodies. Apoptosis of these cells was further confirmed by DNA analysis, which demonstrated the activation of an endogenous endonuclease which cleaved the DNA of these cells into oligonucleosomal fragments. Microtubule disrupting agents were found to exert these effects over a wide range of doses. Apoptosis was also inducible in HL-60 cells, in a dose-dependent manner, by the calcium ionophore A23187. Since microtubules are known to be highly sensitive to intracellular calcium fluctuations, this suggests that calcium influx could act at the microtubule level in effecting apoptosis.

Actin Cytoskeleton↗
PubMed1990

HL-60 cells induced to differentiate towards neutrophils subsequently die via apoptosis.

The human promyelocytic HL-60 cell line can be induced to differentiate to neutrophil-like cells in response to a variety of chemical stimuli. We have found that retinoic acid-treatment of HL-60 cells over a period of 6-8 days resulted in a progressive increase in the proportion of cells with mature neutrophil morphologies and was closely followed by an increase in the proportion of cells exhibiting the morphological characteristics of apoptosis, the non-pathological mode of cell death. Using Percoll step-density gradients we have demonstrated a marked increase in the buoyant density of these cells and have used this density difference to obtain enriched fractions of cells for more detailed study. Degradation of the nuclear DNA of these cells into integer multiples of about 200 base pairs, indicative of endogenous endonuclease activation a major characteristic of programmed cell death, was also demonstrated. From these observations we conclude that the mode of cell death in cultures of terminally differentiated HL-60 cells is that of apoptosis. These results parallel those of a recent report which has shown apoptosis to be the mode of cell death of ageing peripheral blood neutrophils. Because of this, we believe that our observations further validate the use of the HL-60 cell line as a model system for the study of human granulopoiesis in vitro and further, that this model system may be useful for gaining insight into the underlying mechanisms involved in apoptosis.

Cell Differentiation↗
PubMed1989

Nucleotide sequence of the matrix, fusion and putative SH protein genes of mumps virus and their deduced amino acid sequences.

cDNA clones representing the M, F and a putative SH gene of the SBL strain of mumps virus have been prepared and their nucleotide sequence determined. The M gene of mumps virus appears to contain 1253 nucleotides and codes for a protein of 375 amino acid residues (Mr 41,589). The protein is hydrophobic and the deduced amino acid sequence shows homologies with those of other paramyxoviruses. The F gene of the SBL strain was compared to that of the RW strain [Waxham et al. (1987) Virology 159, 381-388]. The F gene is 1727 nucleotides long and codes for a protein of 538 amino acids (Mr 58,789). There are substantial variations between the F gene sequences of various mumps virus strains. The F gene is followed by a small (315 nt) transcription unit which contains an open reading frame of 57 amino acids encoding a very hydrophobic protein (Mr 6712). This may be similar to the SH gene of SV5, although there appears to be no sequence homology between the SV5 SH protein and the putative SH protein of mumps virus. A physical and transcription map of mumps virus indicates the gene order to be 3'-N-P-M-F-SH-HN, similar to that of other paramyxoviruses and SV5 in particular.

Amino Acid Sequence↗
PubMed1989

Examination of eight cases of multiple sclerosis and 56 neurological and non-neurological controls for genomic sequences of measles virus, canine distemper virus, simian virus 5 and rubella virus.

In situ hybridization studies have been carried out on brain samples from eight cases of multiple sclerosis (MS) and 56 non-neurological and neurological controls, using single-stranded 35S-labelled RNA probes prepared against genomic RNA sequences of measles virus, canine distemper virus, rubella virus and simian virus 5. Foci of hybridization were found using probes against the measles virus nucleocapsid protein (N), phosphoprotein and fusion protein gene sequences in two of the MS cases, and also in one control, a case of disseminated cytomegalovirus infection with spinal cord necrosis. This result was confirmed using biotinylated probes prepared against the measles virus N genomic sequence. No hybridization was found in any of the MS or control cases using any of the other viral genome-specific probes.

Astrocytoma↗