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Biomedical subjects

J Kelly

Publications and source records attributed to J Kelly.

At least 127 records · Page 7Linked to original sources
PubMed2000

Biochemical basis for the extreme sensitivity of turkeys to aflatoxin B(1).

Poultry are the most susceptible food animal species to the toxic effects of the mycotoxin aflatoxin B(1) (AFB(1)). Feed contaminated with even small amounts of AFB(1) results in significant adverse health effects in poultry. The purpose of this study was to explain the biochemical mechanism(s) for this extreme sensitivity. We measured microsomal activation of AFB(1) to the AFB(1)-8,9-epoxide (AFBO), the putative toxic intermediate, as well as cytosolic glutathione S-transferase (GST)-mediated detoxification of AFBO, in addition to other hepatic phase I and phase II enzyme activities, in 3-week-old male Oorlop strain turkeys. Liver microsomes prepared from these turkeys activated AFB(1) in vitro with an apparent K(m) of 109 microM and a V(max) of 1.25 nmol/mg/min. Preliminary evidence for the involvement of cytochromes P450 (CYP) 1A2 and, to a lesser extent, 3A4 for AFB(1) activation was assessed by the use of specific mammalian CYP inhibitors. The possible presence of avian orthologues of these CYPs was supported by activity toward ethoxyresorufin and nifedipine, as well as by Western immunoblotting using antibodies to human CYPs. Cytosol prepared from turkey livers exhibited GST-mediated conjugation of 1-chloro-2,4-dinitrobenzene (CDNB) and 3,4-dichloronitrobenzene (DCNB), but at a much lower rate than that observed in other species. Western immunoblotting indicated the presence of alpha and sigma class GSTs and another AFB(1)-detoxifying enzyme, AFB(1)-aldehyde reductase (AFAR). Turkey liver cytosol also had quinone oxidoreductase (QOR) activity. Importantly, cytosol exhibited no measurable GST-mediated detoxification of microsomally activated AFB(1), indicating that turkeys are deficient in the most crucial AFB(1)-detoxification pathway. In total, our data indicate that the extreme sensitivity of turkeys to AFB(1) may be attributed to a combination of efficient AFB(1) activation and deficient detoxification by phase II enzymes, such as GSTs.

Aflatoxin B1↗
PubMed2000

Post-translational modification of p53 protein in response to ionizing radiation analyzed by mass spectrometry.

The p53 tumor suppressor protein promotes cell cycle arrest or apoptosis in response to DNA damage and other forms of stress. p53 protein functions as a transcription factor by binding to specific DNA sequences and regulating the transcription of target genes. This activity of p53 is reported to be regulated by phosphorylation and acetylation occuring at various sites on the molecule. Here, we have used a direct and non-radioactive approach involving mass spectrometric analysis of p53 protein to identify sites that are covalently modified in vivo, either constitutively or in response to ionizing radiation. Following partial purification by immuno-affinity chromatography and enzymatic in-gel digestion, the resulting p53 peptides were analyzed by MALDI-TOF and nanoelectrospray mass spectrometry. Mass spectrometry analyses identified four sites at the N terminus that were phosphorylated in response to irradiation, a single constitutive phosphorylation site at serine 315 and several acetylation sites.

Amino Acid Sequence↗
PubMed2000

Phosphorylation of caldesmon by p21-activated kinase. Implications for the Ca(2+) sensitivity of smooth muscle contraction.

We have previously shown that p21-activated kinase, PAK, induces Ca(2+)-independent contraction of Triton-skinned smooth muscle with concomitant increase in phosphorylation of caldesmon and desmin but not myosin-regulatory light chain (Van Eyk, J. E., Arrell, D. K., Foster, D. B., Strauss, J. D., Heinonen, T. Y., Furmaniak-Kazmierczak, E., Cote, G. P., and Mak, A. S. (1998) J. Biol. Chem. 273, 23433-23439). In this study, we provide biochemical evidence implicating a role for PAK in Ca(2+)-independent contraction of smooth muscle via phosphorylation of caldesmon. Mass spectroscopy data show that stoichiometric phosphorylation occurs at Ser(657) and Ser(687) abutting the calmodulin-binding sites A and B of chicken gizzard caldesmon, respectively. Phosphorylation of Ser(657) and Ser(687) has an important functional impact on caldesmon. PAK-phosphorylation reduces binding of caldesmon to calmodulin by about 10-fold whereas binding of calmodulin to caldesmon partially inhibits PAK phosphorylation. Phosphorylated caldesmon displays a modest reduction in affinity for actin-tropomyosin but is significantly less effective in inhibiting actin-activated S1 ATPase activity in the presence of tropomyosin. We conclude that PAK-phosphorylation of caldesmon at the calmodulin-binding sites modulates caldesmon inhibition of actin-myosin ATPase activity and may, in concert with the actions of Rho-kinase, contribute to the regulation of Ca(2+) sensitivity of smooth muscle contraction.

Actins↗
PubMed2000

O(6)-(4-bromothenyl)guanine improves the therapeutic index of temozolomide against A375M melanoma xenografts.

Tumour resistance to methylating agents is linked to expression of the DNA repair protein O(6)-alkylguanine-DNA alkyltransferase (ATase). There is considerable interest in improving the efficacy of O(6)-alkylating chemotherapy by prior depletion of ATase. We have tested the ability of a modified guanine base, O(6)-(4-bromothenyl)guanine (4BTG), to inactivate ATase and to enhance the anti-tumour effect of temozolomide in an animal model system. A375M human melanoma xenografts were established in the flanks of nude mice. ATase depletion after a single dose of 4BTG or O(6)-BG (20 mg/kg i.p.) was determined over a 24 hr period. Subsequently, we tested the effect of 4BTG (20 mg/kg i.p. daily) and/or temozolomide (80-175 mg/kg i.p. daily) over a 5-day schedule on tumour growth. 4BTG was an effective inactivator of ATase in tumour, producing complete depletion within 2 hr of dosing. Furthermore, it enhanced the tumour growth delay achieved with temozolomide, increasing the tumour quintupling time by 8.7 days (95% confidence interval 6.1-11.3 days, p < 0.0001). Whilst the delay in tumour growth was indistinguishable from that observed with O(6)-benzylguanine (O(6)-BG) and temozolomide, the 4BTG combination resulted in considerably less toxicity (0/9 vs. 2/9 deaths; 6.84% weight loss vs. 9.48%, p = 0.019). 4BTG is a potent inactivator of ATase and enhances the therapeutic ratio of temozolomide in this model system to a greater extent than O(6)-BG.

Adenosine Triphosphatases↗
PubMed2000

The production and biological assessment of cervine interferon gamma.

Cervine interferon gamma (IFN-gamma) was cloned and expressed using an Escherichia coli expression system pET-32. The expressed protein contained a 6 histidine purification tag and an 11 kDa thioredoxin fusion partner 5' to the IFN-gamma molecule. The ability of IFN-gamma to inhibit the killing of Madin-Darby bovine kidney cells by Semliki forest virus was used as a measure of the bioactivity of the recombinant cervine IFN-gamma (rIFN-gamma). It was shown that the presence of the thioredoxin fusion partner 5' to the IFN-gamma molecule did not affect its biological activity. As in the mouse model, it was shown that cervine rIFN-gamma was able to down-regulate the transcription of interleukin 10 mRNA while up-regulating the transcription of interleukin 12 mRNA in lipopolysaccharide-sensitized, peripheral blood mononuclear cells. A prototype ELISA was tested for its ability to detect both recombinant and native IFN-gamma. The ELISA was able to detect rIFN-gamma at concentrations greater than 100 pg/ml. It was also used to detect native IFN-gamma produced by peripheral blood lymphocytes from Mycobacterium bovis infected or vaccinated deer after in vitro restimulation with antigen. The rIFN-gamma and the cervine IFN-gamma specific ELISA provide valuable tools with which to study important zoonotic infections in farmed and wild deer.

Animals↗
PubMed2000

Four-hourly scheduling of temozolomide improves tumour growth delay but not therapeutic index in A375M melanoma xenografts.

PURPOSE: To establish whether temozolomide is more effective against A375M human melanoma xenografts if given every 4 h rather than every 24 h, in order to exploit depletion of the DNA repair protein O6-alkylguanine-DNA alkyltransferase (ATase) by prior doses of the drug. METHODS: ATase depletion in A375M human melanoma xenografts was determined over 24 h after a single dose of temozolomide. The effect of different drug schedules (all of total dose 500 mg/kg) in delaying the growth of the xenografts was tested, and ATase depletion and DNA methylation damage assessed in tumour and normal tissue. RESULTS: Maximal depletion of ATase in tumour, to 2.52 +/- 0.23% of pretreatment levels, occurred 4-8 h after a single 100 mg/kg i.p. dose of temozolomide, with 23.0% recovery of protein levels at 24 h. Scheduling of temozolomide every 4 h increased tumour growth delay (33.6 +/- 1.39 days with temozolomide 100 mg/kg 4-hourly x versus 23.2 +/- 1.43 days with temozolomide 100 mg/kg once daily x 5; P < 0.0001) at the expense of increased toxicity (17.4 +/- 1.55% animal weight loss versus 10.6 +/- 1.27%. respectively). Temozolomide every 4 h did not increase ATase depletion compared with the 5-day schedule, but resulted in greater DNA 06-guanine methylation (29.0% more in tumour, 20.8% in liver and 56.0% in brain, comparing areas under the methylation-time curve). CONCLUSIONS: The 4-hourly schedule of temozolomide delayed tumour growth significantly more than the once-daily and 12-hourly schedules, probably as a result of greater DNA damage inflicted, but also increased toxicity. It remains to be seen if this regimen confers a net benefit over the standard schedule.

Animals↗
PubMed2000

What risk factors tell us about the causes of schizophrenia and related psychoses.

Genetic, epidemiologic, and molecular studies concur that liability to schizophrenia is transmitted through the inheritance of a number of genes of relatively small effect, some of which are shared with other psychoses. Each of these susceptibility genes causes minor deviations that are relatively innocent in themselves, for example, increased lateral ventricular volume, schizotypal personality, or subtle cognitive difficulties. However, when an individual is unlucky enough to inherit several of these traits, their cumulative effect, often compounded by environmental hazards, propels that person over a threshold for the expression of frank psychosis. Early environmental risk factors for schizophrenia include urban and winter birth, fetal malnutrition and hypoxia, and possibly prenatal viral infections; these early hazards have only a modest risk-increasing effect, and operate in the context of genetic risk. Preschizophrenic children are more likely to have minor psychomotor and cognitive problems; low IQ has a linear relationship with risk for schizophrenia. However, schizophrenia is not simply a neurodevelopmental disorder, because risk factors have been identified that have their effects proximal to the onset of psychosis: drug abuse, immigrant status, and social adversity and isolation. Both genetic and environmental risk factors appear to operate across diagnostic categories and therefore support a dimensional model of psychosis.

Brain↗
PubMed2000

Spontaneous conception after a successful attempt at in vitro fertilization/intracytoplasmic sperm injection.

OBJECTIVE: To determine the incidence of spontaneous pregnancy in women who were not actively undergoing therapy after a successful attempt at IVF/intracytoplasmic sperm injection and to characterize its pattern of occurrence. DESIGN: Retrospective postal questionnaire. SETTING: An assisted reproduction unit at a university-based teaching hospital. PATIENT(S): Five hundred thirteen replies were received from 530 questionnaires mailed. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Spontaneous pregnancy. Women who did and did not conceive spontaneously after successful IVF treatment were compared in terms of their age, duration of infertility, previous reproductive history, and indication for treatment at the time of assisted reproduction. RESULT(S): The rate of spontaneous conception among the survey respondents was 20.7%. Younger women (</=34 years of age) had a higher rate of spontaneous conception, as did those with a shorter duration of infertility. Women with unexplained infertility and endometriosis also were more likely to conceive. Few of those who had undergone intracytoplasmic sperm injection conceived, whereas 21.6% of those whose partners had had sperm quality sufficient for IVF later conceived spontaneously. CONCLUSION(S): The chances of spontaneous conception after successful ART therapy are significant in some groups of patients. This has implications for the practice of assisted reproduction and the obstetric care of patients who conceive with treatment. Contraceptive advice may need to be provided to couples who undergo IVF/intracytoplasmic sperm injection.

Adult↗
PubMed2000

Familial idiopathic adulthood ductopenia: a report of five cases in three generations.

BACKGROUND/AIMS: Idiopathic adulthood ductopenia is a cholestatic liver disease of unknown etiology. Although most cases are sporadic, familial cases do occur. METHODS: We describe a series of adult-onset bile duct depletion involving five members of an extended family spanning three generations. The proband, a 49-year-old man, presented in 1989 with asymptomatic elevation of liver enzyme tests. Investigations for chronic liver disease, including endoscopic retrograde cholangiopancreatography, were negative. Findings on liver biopsy progressed from normal in 1989 to striking loss of interlobular bile ducts in 1992. Ursodeoxycholic acid has resulted in improvement of liver enzyme tests. The proband's brother required a liver transplant at age 35 for cryptogenic cirrhosis. The proband's sister, age 42, has had intermittent jaundice and elevation of liver enzyme tests since 1971. Her liver biopsy findings progressed from normal in 1975, to striking bile duct damage by 1997. The proband's 21-year-old son has elevated liver enzyme tests and a liver biopsy consistent with idiopathic adulthood ductopenia. The proband's father had a liver biopsy at age 70 for investigation of a liver mass. It revealed extensive fibrosis and striking bile duct destruction. RESULTS/CONCLUSIONS: This is the largest series of familial idiopathic adulthood ductopenia reported, and the first with multiple generations described. Genetics appears to play a role in some cases of adulthood ductopenia. Ursodeoxycholic acid may be beneficial in the treatment of this condition.

Adult↗
PubMed2000

Comparison of the efficacy and cost effectiveness of pre-emptive therapy as directed by CMV antigenemia and prophylaxis with ganciclovir in lung transplant recipients.

BACKGROUND: CMV disease remains a major complication of lung transplantation and attempts to prevent it have met with marginal success. In a previous study we documented that universal prophylaxis did not prevent CMV disease but merely delayed it, and was very costly. METHODS: We compared the efficacy and cost of pre-emptive therapy with ganciclovir, guided by CMV antigenemia, to that of historic controls that received universal prophylaxis with ganciclovir. CMV antigenemia assay was done routinely and pre-emptive therapy was initiated if greater than 25 CMV positive cells per 100,000 polymorphonuclear cells were found. RESULTS: Nineteen patients were enrolled; 6 of of whom received 12 courses of pre-emptive therapy. The incidence of CMV disease was 26% compared to 38% for the historical controls (p = 0.51). None of the patients that received pre-emptive therapy developed CMV disease following that therapy. Antigenemia failed to predict disease in 5 patients that developed it, and thus it is unknown if pre-emptive therapy could have prevented it. There was no mortality in either the study patients or historic controls directly related to CMV. The net savings with pre-emptive therapy was $2569 per patient. CONCLUSIONS: We conclude that pre-emptive therapy with ganciclovir is as safe and effective as universal prophylaxis in preventing CMV disease in lung transplant recipients, and is less expensive. The appropriate surveillance technique and timing remain to be determine to optimize the efficacy of pre-emptive therapy.

Adult↗
PubMed2000

Immunotherapy against antibiotic-resistant bacteria: the Russian experience with an antistaphylococcal hyperimmune plasmaand immunoglobulin.

The Russian experience with the preparation and clinical application of an antitoxic antistaphylococcal hyperimmune plasma and immunoglobulin is described. The immunotherapies were developed in the late 1960s and put into widespread use in the Soviet Union for the prophylaxis and treatment of sepsis, pneumonia, and other conditions caused by an epidemic of antibiotic-resistant Staphylococcus aureus.

Animals↗
PubMed2000

High risk genes predisposing to prostate cancer development-do they exist?

There is evidence for genetic predisposition to prostate cancer. However, prostate cancer genes have been more difficult to find than genes for some of the other common cancers, such as breast and colon cancer. The reasons for this are discussed in this article and it is now becoming clear that prostate cancer is probably due to multiple genes, many of which are moderate or low penetrance. The advances in the Human Genome Project and technology, especially that of robotics, will help to overcome these problems. Prostate Cancer and Prostatic Diseases (2000) 3, 241-247

Journal Article↗
PubMed2000

Differential expression of lymphoid and myeloid markers on differentiating hematopoietic stem cells in normal and tumor-bearing adult human liver.

The presence and phenotype of lineage-committed hematopoietic progenitors in the normal adult human liver (AHL) were investigated and compared with the profiles of differentiating hematopoietic precursor populations detected in liver bearing metastases of colonic origin. Levels of hematopoietic stem cells (HSCs) (CD34(+)CD45(+)) detected in hepatic mononuclear cell (HMNC) populations were increased 6-fold when compared with matched peripheral blood samples. In normal liver, less than 5% of HSCs expressed the myeloid-associated antigen, CD33, whereas considerable proportions expressed lymphoid-associated markers (T cell, 33.39%; B cell, 17.39%; and natural killer [NK] cell, 37.17%). Significant increases were observed in the relative proportions of hepatic HSCs coexpressing CD33 (20.53%; P =.001), and the T-cell marker (CD7, 58. 13%; P =.02) in tumor-bearing liver compared with normal liver. HSCs with B-cell progenitor phenotype (CD19(+)) were significantly decreased in tumor-bearing liver (0.06%; P =.02). Despite these differences, the activation status of hematopoiesis, as measured by the coexpression of the differentiation and activation markers, CD38 and CD45RA, did not differ significantly between normal and tumor-bearing liver. These results indicate that the normal AHL harbors lineage-committed hematopoietic progenitors, and the vast majority of these progenitors express lymphoid-associated antigens with changes occurring in both the myeloid and lymphoid compartments of the hepatic hematopoietic pathway on tumor challenge. While tumor-bearing livers are enriched for intrahepatic myeloid precursors and T-cell progenitor cells, further studies are required to establish the origin and in situ development potential of hepatic HSCs in the adult human and their role in tumor immunity.

Adolescent↗
PubMed2000

Nutritional status and its relationship to quality of life in a sample of chronic hemodialysis patients.

OBJECTIVE: To assess the relationship between nutritional status and quality of life in a sample of chronic hemodialysis patients. DESIGN: Cross-sectional study. SETTING: Haemodialysis Units of St Vincent's and St George Hospitals, Sydney, Australia. PATIENTS: Sixty-four patients participated in the nutritional assessment, of which 53 completed the quality of life questionnaire. INTERVENTION: Nutritional status was assessed using subjective global assessment in addition to a number of anthropometric and biochemical parameters. Quality of life was assessed by means of a patient questionnaire and assessment of physical functioning. MAIN OUTCOME MEASURES: Nutrition status, 6 quality of life subscales related to general well-being, health and functioning, social and economic, psychological/spiritual well-being, and family life, employment status, income, participation in recreational/sports activities, the number of hospital admissions, days of hospitalization, and lengths of hospital stay. RESULTS: Sixty-four percent of patients were well nourished, 23% were moderately malnourished, and 13% were severely malnourished. Malnutrition was associated with poorer subjective quality after controlling for the affects of sociodemographic and medical variables. Severe malnutrition was also independently associated with poorer physical function, and resulted in significantly more hospital admissions, more days of hospitalization, and longer average lengths of hospital stay. CONCLUSION: Malnutrition is common in chronic hemodialysis patients and is associated with poorer quality of life when the degree of malnutrition becomes severe. Prospective studies are required to determine whether improving the nutritional status of these patients will result in meaningful improvements in quality of life and other medical outcomes.

Adult↗
PubMed2000

Serum haptoglobin: an objective indicator of experimentally-induced Salmonella infection in calves.

Experimental models of Salmonella -induced gastroenteritis have previously relied on crude subjective clinical markers of infection to assess disease severity. The aim of this study was to investigate the possibility that changes in serum levels of the acute phase protein, haptoglobin, may be used as an objective, quantitative measurement of infection. Eight 3- to 4-week-old animals were challenged with a mixture of three Salmonella serotypes containing 6 x 10(10)bacteria and compared with five animals given a placebo preparation. Animals were monitored and characteristic clinical symptoms of infection; diarrhoeal scores, morbidity scores and rectal temperature, were recorded. Serum samples, from both animal groups, taken prior to challenge and again on days 1, 3, and 5 post-challenge, were analysed for haptoglobin levels using a direct serum binding assay. Prior to challenge, all 13 animals had normal levels of haptoglobin in their serum. By day 3 post-challenge six of eight animals challenged with Salmonella had abnormal serum haptoglobin levels (median level = 212 microg ml(-1)), while haptoglobin levels remained normal in placebo-challenged animals (median level = 0 microg ml(-1)). The change in haptoglobin levels during the 5-day observation period was statistically significant in the Salmonella -challenged animals (P = 0.0003, H = 16.477). Serum haptoglobin levels showed a statistical correlation with clinical measures of disease severity; diarrhoeal scores (P = 0.0015, H =8. 988), morbidity scores (P = 0.0004, H = 15.711) and rectal temperature (P = 0.0001, Z = 4.304). Thus, serum haptoglobin levels closely reflect the clinical symptoms of infection and are therefore a useful marker of infection severity in salmonellosis in calves.

Animals↗