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Biomedical subjects

F Wong

Publications and source records attributed to F Wong.

At least 181 records · Page 10Linked to original sources
PubMed1989

Changing character of cervical cancer in young women.

To examine the hypothesis that the pattern of cervical cancer is changing data on women presenting with the disease over 34 years were studied retrospectively. During 1953-86, 2628 women with cervical cancer were referred to a large tertiary referral hospital in Sydney; 418 were aged 35 or less. During the period of review the proportion of young women with the disease increased from under 9% in the 1950s and 1960s to about 25% in the 1970s and 1980s; a similar but less pronounced trend was apparent for the whole of New South Wales in the 1970s and 1980s. The prevalence of less common morphological types of cervical cancer increased throughout the period, particularly in the young. Pelvic lymph node metastases were identified in younger patients with stage Ib and IIa tumours more commonly in the later years of the study, suggesting that the disease was becoming more severe. Overall rates of recurrence improved over time, but an apparent increase in early recurrences was observed in young patients with Ib and IIa tumours and without nodal disease. The results suggest that the clinical and pathological behaviour of cervical cancer changed over the period of review.

Adult↗
PubMed1989

Proper function of the Drosophila trp gene product during pupal development is important for normal visual transduction in the adult.

The response of invertebrate photoreceptors consists of the summation of quantum bumps, each representing the response to a single photon. The bumps adapt depending on the intensity of the stimulus: their average size is relatively large in dim light and small in bright light. The rate of occurrence of the bumps varies proportionally with light intensity. In the Drosophila mutant trp, unlike in the wild type, the rate does not increase with increasing light intensity and the bumps do not adapt. Here we report an analysis of the trp gene and its expression in normal and mutant flies. Our results suggest that the trp protein is a novel photoreceptor membrane-associated protein, that this protein is not required for the occurrence of bumps but is necessary for adaptation, and that proper function of the trp gene product during pupal development is important for normal visual transduction in the adult.

Amino Acid Sequence↗
PubMed1989

Mutation of host cell determinants which discriminate between lytic and persistent mouse hepatitis virus infection results in a fusion-resistant phenotype.

The expression of mouse hepatitis virus (MHV) E2-specific mRNA, the E2 polypeptide and its associated cell fusing activity was monitored in various cell types inoculated with a recombinant vaccinia virus, designated vMS containing the E2 gene. The results suggest that host cell permissiveness to MHV infection correlates with cellular susceptibility to membrane fusion mediated by the MHV E2 glycoprotein. In addition, we utilized a genetic approach to the analysis of host cell functions involved in determining permissiveness to MHV. By using the chemical mutagen ethyl methanesulphonate, mouse fibroblast cell mutants were generated and selected for their resistance to cell killing by MHV. When challenged with MHV, all five mutants examined gave rise to persistent infections, in contrast to wild-type L-2 cells which were rapidly killed by the virus. The results provide genetic evidence in support of a previous correlation proposed between MHV permissiveness and two host determinants, namely susceptibility to MHV infection and to MHV-mediated cell fusion. Fusion resistance was specific to fusion mediated by the MHV E2 glycoprotein as shown in contact fusion assays between uninfected cells and cells infected either with MHV or with an E2-expressing recombinant vaccinia virus. In contrast, mutant cells were not resistant to fusion after treatment with polyethylene glycol. The observed high rate of generation of these mutants suggests that the conversion of a fully MHV-susceptible cell to a semi-resistant one is a fairly common event, possibly involving a single mutation. In this case, resistance to MHV infection and to E2-mediated membrane fusion may depend on a common host function. This result provides prospects for the precise genetic and biochemical characterization of the steps involved in host cell permissiveness to MHV infection.

Animals↗
PubMed1989

A model for persistent murine coronavirus infection involving maintenance via cytopathically infected cell centres.

The relatively cell impermeable hygromycin B was found to inhibit viral but not cellular protein synthesis when added to cultures of murine hepatitis virus (MHV)-infected or mock-infected mouse L-2 fibroblasts. Membrane permeability, as judged by influx of sodium ions, has previously been demonstrated to be an MHV E2 glycoprotein-mediated, cytopathic effect of MHV infection in L-2 cells. It is therefore likely that the selective effect of hygromycin B on viral protein synthesis is a reflection of an increased drug penetration into virus-infected cells. Using hygromycin B as a marker for MHV-induced cell membrane cytopathology, the effects of drug treatment on a persistent MHV infection in mouse LM-K fibroblasts were investigated. MHV persistence in LM-K cells, which normally involves a steady state infection of 0.1 to 1% of the cells in culture, was found to be cured by hygromycin B treatment, as measured by the elimination of infectious virus from the supernatant medium. Hygromycin B also resulted in the eradication of MHV-specific RNA from LM-K cells, arguing against the presence of a non-cytopathically or latently infected subpopulation of cells.

Animals↗
PubMed1989

Serum C-reactive protein levels in patients with cervical neoplasia.

Serum C-reactive protein (CRP) levels were determined by enzyme immunoassay in 56 patients with invasive carcinoma of the cervix, 34 patients with cervical dysplasia and 24 women with no evidence of cervical pathology. The logarithmic CRP values were significantly higher in patients with invasive carcinoma when compared with the controls (p less than 0.05). Measurement of serum CRP in cancer patients grouped according to their clinical stages failed to reveal any relationship with the extent of the disease.

C-Reactive Protein↗
PubMed1987

Role of superoxide in radiation-killing of Escherichia coli and in thymine release from thymidine.

The role of superoxide and hydroxyl radicals in gamma-radiation-killing of Escherichia coli K12 was studied in aerated suspensions supplemented with formate, phosphate, superoxide dismutase, catalase and saturated with nitrous oxide. Nitrous oxide, which converts e-aq to .OH, caused decreased radiosensitivity. On the other hand, formate, which results in conversion of .OH to .O2-, resulted in an increased radiosensitivity. The results implicated .O2- as a major cause of radiation-mediated cell-killing. The addition of the enzymes, superoxide dismutase or catalase to the E. coli suspensions prior to and during irradiation had no effect on cell survival, indicating that the biologically significant site of generation and action of .O2- is an intracellular one. Further studies were undertaken to examine the role of superoxide in DNA damage. The release of thymine from the DNA base, thymidine was studied as a result of gamma-irradiation and of chemically generated superoxide (using KO2 in dimethyl sulfoxide). Thymine was identified by HPLC and mass spectrometry. C-13 NMR analysis of the reaction mixture of thymidine with KO2 in dimethyl sulfoxide provided evidence for attack of .O2 at the ribosyl Cl' atom.

Catalase↗
PubMed1987

Overlapping transcription units in the transient receptor potential locus of Drosophila melanogaster.

We report the identification in Drosophila melanogaster of two mRNA transcripts that are derived from the transient receptor potential locus by transcription in opposite directions. The two transcripts overlap; one transcript has, as part of its 5'-untranslated sequence, the reverse complement of 442 bp of the 3' terminus of the transcript derived from the opposite DNA strand. Conceptual translation of the corresponding cDNA sequences predicted for one of the transcripts a polypeptide whose C terminus shares sequence and structural similarity with the cell-wall-binding domain of protein A from Staphylococcus aureus; for the transcript derived from the opposite DNA strand, a polypeptide of 264 amino acids was predicted, which showed no significant sequence homology with any known protein. The two transcripts have different tissue specificities: one is expressed predominantly in the eye and the other is in the body. These findings may have implications in the relationship between the organization of overlapping genes on opposite DNA strands and regulation of gene expression by antisense RNA.

Amino Acid Sequence↗
PubMed1987

Immunocytochemical localization of photopigments in cephalopod retinae.

The photopigments, rhodopsin and retinochrome, have been localized in cephalopod retinae using light and electron microscopic immunocytochemical methods. Polyclonal antibodies prepared against squid opsin demonstrated the presence of this protein in the photoreceptor rhabdomes, Golgi zone, Golgi-associated vesicles, plasma membrane, large cytoplasmic vesicles, and axonal membranes of octopus retinae. Monoclonal anti-opsin immunostained the rhabdomes and multivesicular bodies in the photoreceptor inner segments of squid. We believe the multivesicular bodies are involved in rhabdome turnover. Polyclonal anti-retinochrome localized this photopigment to the myeloid bodies of the photoreceptor inner segments, the rhabdomes, and to the extracellular space between opposing rhabdomeres in octopus retina. The results suggest some interesting functional relationships between rhodopsin and retinochrome with regard to chromophore exchange between illuminated forms of these photopigments and chromophore addition to newly synthesized opsin.

Animals↗
PubMed1987

Translational regulation in mouse hepatitis virus infection is not mediated by altered intracellular ion concentrations.

Infection of mouse L-2 fibroblasts with mouse hepatitis virus (MHV) results in strong inhibition of host cell protein synthesis. Since it has been suggested in other virus systems that translational control is modulated by changes in the intracellular ionic environment, we investigated the possible occurrence of similar changes during MHV infection. Membrane permeability to extracellular sodium ions was measured by culturing MHV-infected cells in the presence of 22Na+. Sodium influx into MHV-infected cells rose dramatically from 4 to 6 h post-infection. This influx correlated chronologically with the expression of MHV-mediated cell fusion. Cell fusion was blocked by the addition of a monoclonal antibody against the MHV E2 glycoprotein. This addition also resulted in a reduction in the normal influx of 22Na+, suggesting that E2 expression was responsible, directly or indirectly, for the increased permeability to sodium ions in infected cells. Cultures of MHV-infected cells were labelled with [35S]methionine in the presence of medium supplemented with sodium chloride at final concentrations ranging from 150 mM to 350 mM. Incorporation of radiolabel into proteins decreased with increasing NaCl concentration; however, the ratio of viral to cellular protein synthesis remained relatively constant. Similarly, alteration of intracellular Na+ and K+ levels by treatment of infected cells with ouabain had little effect on the pattern of viral/cellular protein synthesis. Using monoclonal anti-E2 antibody to inhibit Na+ influx, we demonstrated normal inhibition of host cell protein synthesis. We therefore conclude that MHV-induced shut-off of host translation is not mediated by changes in intracellular Na+ concentrations.

Animals↗
PubMed1987

The evaluation of a pregnancy test (Tandem ICON) in the management of ectopic pregnancy.

A comparison was made between the Tandem ICON and Gravindex tests in the management of suspected ectopic pregnancy in 38 patients. The Tandem ICON test was significantly more accurate than the Gravindex in predicting an ectopic pregnancy. After the exclusion of cases with intrauterine pregnancy, there was no error when the Tandem ICON test was used, but 8 false negative cases were found with the Gravindex.

Antibodies, Monoclonal↗
PubMed1987

Age-related changes in humoral and cell-mediated immunity in Down syndrome children living at home.

Abnormalities of humoral and cell-mediated immunity have been described in Down syndrome but reported findings have been inconsistent. Confounding factors have included age, institutional versus home life, hepatitis B antigenemia, and zinc deficiency. To clarify this problem, we studied 64 children with Down syndrome (DS) compared with an age-matched control group. All children had always lived at home. All the DS children were negative for hepatitis B surface antigen. Serum zinc concentration in the DS group was on average 12 micrograms/dl lower than age-matched control children. They also had significantly lower levels of immunoglobulin M, total lymphocyte count, T and B lymphocytes, and T helper and suppressor cells. In vitro lymphocyte response to phytohemagglutinin and concanavalin A was significantly reduced at all ages in the DS group. Lymphocyte response to pokeweed mitogen increased with age in control children but decreased in the DS children. By 18 yr, the mean response for DS was 60000 cpm lower than controls. The DS group had significantly higher concentrations of immunoglobulins A and G than controls and the difference increased with age. Complement fractions C3 and C4 were also higher in the DS group at all ages. The number of HNK-1 positive cells was higher in the DS group than controls at all ages. When hepatitis and institutionalization are excluded as confounding factors, DS children still differ in both humoral and cell-mediated immunity from an age-matched control group.

Adolescent↗
PubMed1987

A DNA deletion associated with multiple impaired transcripts in the visual mutant TRP.

The transient receptor potential (trp) mutant in Drosophila is known to manifest retinal degeneration and involves defects in the intermediate steps of visual transduction. The chromosome walking technique has been conducted at the cytogenetic location of trp. Overlapping phage clones that cover a DNA stretch of 73 kb were obtained. Southern blotting studies detected a 2.3 kb DNA deletion within this region in the mutant. The deleted DNA fragment contains exons of three transcripts with lengths of 3.5, 1.5 and 0.8 kb. The transcription of the 3.5 and 1.5 kb RNAs is completely abolished in the mutant, whereas that of 0.8 kb RNA appears to be modified. The impairment in production of three RNAs, due to the DNA deletion, offers a possible molecular basis of the multiple defects displayed by the trp- phenotype.

Animals↗
PubMed1986

Symptoms associated with myocardial infarction: are they of diagnostic value?

Symptoms experienced by 227 consecutive patients before their admission to the coronary care unit were identified by questionnaire and those associated with myocardial infarction (98) compared with those occurring with ischaemia (53) and chest pain or discomfort of unknown cause (29). The diagnosis of myocardial infarction by the nature of the resultant pain or discomfort was unreliable in contrast to the associated symptoms sweating, nausea, belching and vomiting. The predictive value of the latter was 91%. Nausea was associated with inferior site of infarction and development of Q waves on the electrocardiogram. Morphine administration was not followed by an increased incidence of vomiting. Back pain or discomfort during infarction was experienced twice as often by women.

Adult↗
PubMed1986

Pregnancy outcome following radiotherapy for naso-pharyngeal carcinoma.

Nasopharyngeal carcinoma complicating pregnancy is uncommon, and its treatment with irradiation is problematical, as the irradiation risks in pregnancy have not been well defined. In this paper, we described a pregnant patient with nasopharyngeal carcinoma who received irradiation treatment during the pregnancy. The management and the risk of irradiation are discussed.

Adult↗