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Biomedical subjects

G M Jones

Publications and source records attributed to G M Jones.

At least 73 records · Page 4Linked to original sources
PubMed1990

Carrier detection in xeroderma pigmentosum.

We were able to detect clinically normal carriers of xeroderma pigmentosum (XP) genes with coded samples of either peripheral blood lymphocytes or skin fibroblasts, using a cytogenetic assay shown previously to detect individuals with cancer-prone genetic disorders. Metaphase cells of phytohemagglutinin-stimulated T-lymphocytes from eight individuals who are obligate heterozygotes for XP were compared with those from nine normal controls at 1.3, 2.3, and 3.3 h after x-irradiation (58 R) during the G2 phase of the cell cycle. Lymphocytes from the XP heterozygotes had twofold higher frequencies of chromatid breaks or chromatid gaps than normal (P less than 10(-5)) when fixed at 2.3 or 3.3 h after irradiation. Lymphocytes from six XP homozygotes had frequencies of breaks and gaps threefold higher than normal. Skin fibroblasts from an additional obligate XP heterozygote, when fixed approximately 2 h after x-irradiation (68 R), had a twofold higher frequency of chromatid breaks and a fourfold higher frequency of gaps than fibroblasts from a normal control. This frequency of aberrations in cells from the XP heterozygote was approximately half that observed in the XP homozygote. The elevated frequencies of chromatid breaks and gaps after G2 phase x-irradiation may provide the basis of a test for identifying carriers of the XP gene(s) within known XP families.

Adolescent↗
PubMed1990

Performance studies of an enzyme-linked immunosorbent assay for detecting Staphylococcus aureus antibody in bovine milk.

An enzyme-linked immunosorbent assay (ELISA) for detecting Staphylococcus aureus antibody in bovine milk samples was examined for repeatability. A set of 51 bovine milk samples from 4 universities with confirmed culture results was assembled, and a panel of 30 milk samples was randomly selected. When the selected panel was tested at the collection laboratory, there was 97% agreement between the ELISA and the culture test. The panel was tested with the ELISA by the 4 university laboratories. Results were scored by both visual and optical density reader methods. When compared to reference ELISA results, the university laboratory ELISA results showed an agreement of 99.8% for negative samples, 98% for positive samples, and 99% for all samples. Additional studies on 19 milk samples that cultured positive for bacteria other than S. aureus showed 100% specificity. Overall comparison of ELISA and culture results showed high agreement between the 2 techniques. Disagreement appeared to result from explainable differences in antibody and bacterial levels and not from errors in either of the 2 techniques.

Animals↗
PubMed1989

G2 chromosomal radiosensitivity in families with ataxia-telangiectasia.

Ataxia-telangiectasia (A-T) is an autosomal recessive disease involving chromosomal instability, susceptibility to cancer and X-ray hypersensitivity. The latter two features are expressed to a limited extent in the heterozygous carriers of A-T mutations. Although fibroblast lines from A-T heterozygotes clearly show increased susceptibility to the lethal effect of X-irradiation, the difference in post-irradiation survival between cell lines and normal controls is not always large enough to allow the use of X-ray sensitivity as a laboratory assay for carrier detection in A-T. Recently, we have shown in a blind study, that the extent of chromatid damage induced in the G2 phase of the cell cycle by moderate doses of X-rays is markedly higher in A-T heterozygous cells than in normal controls. We have now applied this test to 6 additional obligatory heterozygotes and 24 individuals with different risks of being A-T carriers, from three Israeli A-T families. All 6 cell lines from the obligatory heterozygotes showed the typical hypersensitivity to the clastogenic action of X-rays in G2; of the 24 cell lines with unknown A-T genotype, 16 showed the same hypersensitivity, and 8 responded in a normal way. The proportion of cell lines showing the "A-T-heterozygous phenotype" was in accord with the expected value, based on Mendelian chance calculations. Since these observations were made, a daughter of two hypersensitive parents in one of these families has been diagnosed as having A-T. This confirmed the presumed A-T heterozygosity of the parents, as indicated by the laboratory assay.

Ataxia Telangiectasia↗
PubMed1989

Cortisol level predicts myocardial infarction in patients with ischaemic chest pain.

Serum cortisol levels were studied in twenty patients with confirmed myocardial infarction and in twenty patients with severe chest pain admitted to the coronary care unit with suspected myocardial infarction but in whom a diagnosis of angina was subsequently made. Cortisol levels were significantly elevated in patients within five hours of the onset of symptoms in myocardial infarction (857 +/- 74 nmol/l; mean +/- SE) but remained within the normal range for those with angina (340 +/- 55 nmol/l). It is concluded that hypercortisolaemia accompanies myocardial infarction, but not angina, and that the psychological stresses of ischaemic chest pain and admission to the coronary care unit produce little, if any, elevation in serum cortisol levels unless there is significant myocardial necrosis. This observation may be of value to those conducting intervention studies in myocardial infarction since the early elevation of the cortisol levels to above the normal range in patients with ischaemic chest pain is both sensitive (70%) and specific (85%) for myocardial infarction.

Adult↗
PubMed1989

Central odontogenic fibroma. A report of two controversial cases illustrating diagnostic dilemmas.

Two unusual cases of central odontogenic fibroma are described and used to illustrate differential diagnostic problems in this controversial group of lesions. The first case had a cystic lesion noted on routine radiography in the left ramus of the mandible. This particular case was unusual histologically as it showed in addition to typical areas of odontogenic fibroma a small inflamed cyst lined by epithelium containing many hyaline bodies. The second case presented with anaesthesia of the right lower lip and an enlarged chin prominence. The lesion was diagnosed as an odontogenic fibroma but with a somewhat unusual histological appearance in that there were abundant areas of osseous metaplasia throughout the lesion.

Adult↗
PubMed1989

Carotico-cavernous fistula presenting as a late complication of facial trauma.

A case of carotico-cavernous fistula following facial trauma is reported. Clinical details of the case are described together with a review of the literature. Aetiology and treatment of the condition are discussed. Carotico-cavernous fistula is a rare complication of facial trauma. The case reported is important because the complication presented as a late event some 9 weeks after the initial trauma.

Adult↗
PubMed1989

Factors affecting and significance of G2 chromatin radiosensitivity in predisposition to cancer.

The frequencies of chromatid breaks and gaps in metaphase cells fixed 2 h after G2 phase X-irradiation (1 Gy) were in almost all cases at least two- to three-fold higher in skin fibroblasts from individuals with genetic conditions predisposing to cancer than in comparable cells from clinically normal controls. Previously, we reported this response in all cancer-prone genetic disorders tested including ataxia telangiectasia, Bloom's syndrome, Fanconi's anemia, xeroderma pigmentosum (XP), familial polyposis, Gardner's syndrome, hereditary malignant melanoma, dysplastic nevus syndrome and cancer family members. One exception was XP-A. In this report we add information on skin fibroblasts from retinoblastoma, Wilms' tumor and XP-C patients, 13 clinically normal controls and six cell lines from fetal or infant cells. Factors affecting the response are identified and include pH, temperature, cell density, culture medium or serum, microbial contamination and visible light exposure (effective wavelength 405 nm). Because of experimental variability, known normal controls should be used in each group of assays. With adequate control of the above factors this response could provide the basis of a test for detecting individuals carrying genes that predispose to a high risk of cancer.

Cell Line↗
PubMed1989

Deficient G2 phase repair of radiation-induced chromatin damage in the SENCAR mouse.

The SENCAR mouse, selectively bred for sensitivity to skin tumor induction by two-stage chemical carcinogenesis, is also genetically hypersensitive to skin carcinogenesis by high doses of UV. Skin fibroblasts from the SENCAR mouse exposed during G2 phase to radiation associated with intracellular hydroxyl radical formation, i.e. X-rays or near UV/visible light, showed a higher frequency of chromatid breaks at 2 h post-irradiation than skin fibroblasts from six other inbred strains of mice including C3H/HeN. However the level was similar to that reported previously for the BALB/cAn mouse known to be resistant to chemical carcinogenesis of skin. When exposed for 2 h to visible light (8 W/m2), chromatid breaks persisted in fibroblasts from the SENCAR mouse during the 4 h post-irradiation period, but showed an abrupt decline in C3H/HeN fibroblasts within 1 h after irradiation. Skin fibroblasts from the tumor-sensitive SENCAR mouse differed from those of the resistant BALB/cAn in response to beta-cytosine arabinoside (ara-C) an inhibitor of the repair polymerase. Ara-C added to cultures of SENCAR and BALB/cAn cells after G2 X-irradiation (68R) increased chromatid gaps 18-fold and breaks 2-fold in BALB/cAn cells but had no effect on SENCAR cells even though incorporated into DNA to the same extent. The present results suggest that the SENCAR mouse is deficient in at least two aspects of DNA repair: (i) ligation or a prior step in the repair process leading to ligation and (ii) repair endonucleolytic incision at DNA lesions induced by irradiation.

Animals↗
PubMed1989

An analysis of human oocytes and follicles from stimulated cycles: oocyte morphology and associated follicular fluid characteristics.

The aim of this study was to determine whether certain characteristics of the follicular biochemistry, previously shown by us to be associated with oocyte developmental capacity, also reflected differences in oocyte appearance, and to determine the range of oocyte characteristics induced by ovarian stimulation. A representative sample of 33 human oocytes and associated follicular fluids was obtained after a follicular growth period considered suitable for IVF. Individual follicular fluid protein and proteoglycan levels, and follicular volume were compared with the morphological characteristics of each oocyte. Oocytes which retained the germinal vesicle nuclear status after exposure to human chorionic gonadotrophin tended to occur in small follicles (less than or equal to 2 ml) and to be highly vacuolated and with characteristic predicted a low potential for cleavage. Among those oocytes which had progressed to MII nuclear maturity [in the medium (2.5-6.5 ml) and large (greater than or equal to 7 ml) volume follicles] the degree of oocyte vacuolation was negatively correlated with alpha 1-antitrypsin level, while the degree of organelle clumping was correlated with proteoglycan and immunoglobulin levels. Only five of the oocytes (15%) in this sample had follicular characteristics consistent with a normal potential for pregnancy. These MII oocytes occurred within the medium volume range, had low vacuolation levels, and a low degree of organelle clumping. In contrast, those oocytes with a low potential for cleavage based on their follicular biochemistry, showed high cytoplasmic vacuolation levels.

Cell Nucleus↗
PubMed1989

Effectiveness of intramammary antibiotic therapy based on somatic cell count.

The Virginia Tech dairy herd was used in a 10-mo study to determine the effect of intramammary antibiotic therapy of quarters with elevated SCC on milk production, subsequent DHIA SCC, and infection status. Cows were assigned randomly to experimental or control groups. Animals in both the control and experimental groups with SCC scores greater than or equal to 5 for the first time during that lactation were quarter sampled, milk was cultured to detect presence of mastitis pathogens, and SCC was determined. All experimental cows with quarter SCC greater than or equal to 5 were treated with an intramammary cephapirin product only in those elevated quarters (DHIA SCC greater than or equal to 5), regardless of clinical symptoms. Control cows received antibiotic therapy when symptoms were clinical, regardless of SCC. Treatment group had no significant effect on milk production, SCC, or infection status of the cow. Treatment of cows in the experimental group cured 70% of infected quarters, whereas only 50% of infections in the control group were eliminated.

Animals↗
PubMed1988

Comparisons of on-farm screening tests for detection of antibiotic residues.

A study was conducted to determine the effectiveness of on-farm tests for detection of antibiotic residues in milk and urine. Composite milk samples (n = 122) were taken from 58 cows receiving antibiotic treatment with a single antibiotic by any route of administration. Samples were obtained 72 h posttreatment, and sampling continued every 24 h until all residue tests showed a negative result for antibiotics. Antibiotic residues were detected by the Bacillus stearothermophilus disc assay, the Delvotest P, and the Penzyme test. Urine of cull cows was collected and tested for residues with the Live Animal Swab Test for antibiotic residues present in slaughter carcasses. No significant difference was found between the Bacillus stearothermobilus disc assay and either on-farm test. Chi-square analysis indicated that with both the Delvotest and the Penzyme test, 17% of samples gave positive results when the disc assay showed negative readings. An inordinately high percentage (69%) of urine samples from cull cows exhibited antibiotic contamination, although all animals had completed the specified withholding periods. Fifteen of these positive results were obtained from primiparous cows that had never been treated with any antibiotic.

Animals↗
PubMed1988

Cowside antibiotic residue testing.

Detectable concentrations of antibiotic residues in milk supplies are illegal. They interfere with manufacturing of some dairy products, may cause hypersensitivity or resistance to drug therapy in humans, and are perceived by consumers as undesirable. Antibiotics are used for intramammary, intramuscular, oral, or reproductive therapy to counter acute or subacute diseases. Residues can result for many reasons, including poor records of treatment, failure to observe recommended label withdrawal time, prolonged drug clearance, treated animal identification problems, products not used according to label directions, lack of advice on withdrawal period, and others. Several effective and useful on-farm residue screening tests are available and should be used to monitor cows treated with an antibiotic for any reason. Herds that use drugs without label directions or that do not follow label directions should find these tests valuable. Producers must understand how to interpret the results of these tests. Also, dairy farmers must recognize if the selected test method is capable of detecting those antibiotics in use and what are to be monitored.

Animals↗
PubMed1988

Persistence of residues in milk following antibiotic treatment of dairy cattle.

A study was conducted to determine the persistence of antibiotic residues in milk beyond the recommended withdrawal period. Composite milk samples (n = 122) were collected from 58 lactating dairy cows in the university herd receiving antibiotic treatments for any reason but only when administered as a single drug. Samples were obtained 72 h posttreatment and sampling continued every 24 h until result for antibiotic residue was negative by the Bacillus stearothermophilus disc assay. The antibiotic (n = 7) administered accounted for significant variation in drug persistence; however, route of administration, case number (for cows treated for more than one episode), number of days treated, animal's body weight, lactation number, and daily milk production did not affect drug persistence. Chi-square analysis indicated that 21% of milk samples were positive for residues beyond the recommended withholding period. Milk samples from cows treated with cephapirin and penicillin were the only samples that exceeded recommended withdrawal times. Often doses administered exceeded label directions.

Animals↗
PubMed1987

Hypersensitivity to G2 chromatid radiation damage in familial dysplastic naevus syndrome.

Skin fibroblasts from 25 members of nine kindreds with familial dysplastic naevus syndrome (DNS), 12 apparently normal spouses, and 11 additional unrelated normal individuals were tested for G2 cell-cycle phase sensitivity to ionising radiation. The cells from individuals with DNS or hereditary cutaneous malignant melanoma with DNS (HCMM/DNS) had significantly more chromatid breaks and gaps when entering metaphase 0.5-1.5 h after G2 phase X-irradiation (1 Gy) than those from unaffected controls. In two cases, the test results positively identified individuals before the clinical diagnosis of DNS. A clinically normal obligate carrier of the HCMM/DNS gene showed the enhanced G2 radiosensitivity. Moreover, in a test on 1 proband, the sensitivity was apparent in peripheral blood lymphoblasts. Enhanced G2 chromatid radiosensitivity may be a marker of genetic susceptibility to HCMM/DNS.

Adult↗