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.

An unusual case of enterococcal tricuspid valve endocarditis

A 52-year-old male smoker presented with a 10-week history of weight loss and malaise, together with a 1-week history of left-sided pleuritic chest pain, haemoptysis and mild dyspnoea. He had used intravenous drugs for a short time 30 years previously although he denied any intravenous drug use since. There was no other past medical history of note.

On examination, he was thin and appeared chronically unwell. He was apyrexial. There was a left pleural rub. There were no murmurs or stigmata of endocarditis. There were no other findings of note.

Full blood screen was normal apart from a white cell count of 11.2x109/litre (normal range 4.0–11.0x109/litre). Erythrocyte sedimentation rate was 52 mm/hr and C-reactive protein was 16 mg/litre (normal range <7.0 mg/litre). Urinalysis and urine culture were normal. The chest X-ray showed a circumscribed left lower zone lesion (Figure 1). Figure 2 shows the computed tomography appearance of the lesion.

At this stage, pulmonary malignancy was suspected (either a primary or secondary). The following day, two sets of blood cultures were taken in view of a low grade pyrexia. Enterococcus faecalis grew from all four bottles and the patient was started on intravenous amoxycillin.

Five days after admission a new soft pansystolic murmur at the left sternal edge was noted. Intravenous gentamicin was added. Transthoracic echocardiogram was normal but was repeated after an interval of 10 days in view of continuing low grade pyrexia and at this stage showed a vegetation adherent to the tricuspid valve (Figure 3).

The patient was treated with intravenous amoxycillin and gentamicin for a total of 6 weeks. He did not develop any further complications and has remained well at follow up.

An unusual cause of bruising in an 80-year-old woman

PRESENTATION

a previously fit 80-year-old woman presented with a 2-week history of spontaneous and extensive bruising affecting all four limbs. The severity was such that she required a transfusion of 8 units of blood.

RESULTS OF INVESTIGATIONS

a markedly prolonged activated partial thromboplastin time which was only partially corrected with normal plasma; tests for lupus anticoagulant were negative. Factor VIII levels were reduced and the Bethesda assay indicated an acquired inhibitor to factor VIII. She was treated with a combination of intravenous immunoglobulin and immunosuppression.

OUTCOME

the response to treatment was excellent, with a marked reduction in anti-factor VIII antibody levels and resolution of the bruising over the next few weeks.

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.

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.

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.

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.

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.

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.

Diabetes care: a comparison of management systems

During 1997, the Alaska Area Diabetes Program audited a sample of 837 charts from among the 1373 individuals receiving regular diabetes care at facilities serving predominantly American Indians/Alaska Natives. Charts were evaluated for the delivery of American Diabetes Association Standards of Care. Results of the audit showed a great deal of variability among facilities. Facilities which scored highly in the audit were more likely to use an organized multidisciplinary team approach that included coordinated clinic appointments with multiple providers on the same day, maintenance of a diabetes registry, proactive preclinic preparation, flow-sheet use, intensive individual nutritional counseling, a case manager or field clinic coordinator system with standing orders, and strong self-management support.

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.

An outpatient psychiatry program for offenders with mental disorders found not guilty by reason of insanity

OBJECTIVE

Rehospitalization and criminal recidivism were examined among a group of offenders with mental disorders adjudicated as not guilty by reason of insanity and mandated to receive treatment in a forensic psychiatric outpatient program as a condition of release.

METHODS

A retrospective chart review was conducted for 43 offenders with mental disorders who were acquitted as being not guilty by reason of insanity for the index offense and were active in the outpatient treatment program in 1996. Data were abstracted on sociodemographic, psychiatric, and criminal characteristics predating the index offense; rehospitalizations and new crimes and rearrests after the offense; and clinical and psychosocial functional outcomes after enrollment in the outpatient program.

RESULTS

For the 43 patients, the mean length of stay in the program was 68 months, with a range of 4.9 months to 18.4 years. Almost two-thirds of the patients were diagnosed as having schizophrenia, schizoaffective disorder, or a nonaffective psychotic disorder; 58 percent had a comorbid substance use disorder, and 63 percent had an axis II diagnosis. Since program enrollment, 20 patients (47 percent) were rehospitalized at least once, and eight (19 percent) were rearrested or had committed a new crime. At the end of 1996, only nine (24 percent) were in full remission, and 26 (68 percent) showed at least one indicator of difficulty reintegrating into the community.

CONCLUSIONS

Even after treatment in a specialized forensic program, this sample of offenders with serious mental disorders remained impaired symptomatically and functionally. Although avoidance of rehospitalization is considered a successful outcome, rehospitalization is preferable to rearrest for this forensic population.

Targeting improves the efficacy of a DNA vaccine against Corynebacterium pseudotuberculosis in sheep

A large-scale DNA vaccination trial was performed with sheep to investigate whether an antigen targeted by CTLA-4 enhanced and accelerated the humoral immune response. Vaccination with genetically detoxified phospholipase D (DeltaPLD) has been shown to be effective, at least partially, against Corynebacterium pseudotuberculosis, the causal agent of caseous lymphadenitis in sheep. CTLA-4 binds to B7 on antigen-presenting cells and thus was used to direct the fusion antigens to sites of immune induction. Here we demonstrated that targeting DeltaPLD as a CTLA-4 fusion protein significantly enhanced the speed, magnitude, and longevity of the antibody response compared to that obtained with DNA encoding DeltaPLD. While all groups of sheep vaccinated with DNA encoding DeltaPLD were afforded better protection against an experimental challenge with C. pseudotuberculosis than those immunized with an irrelevant plasmid or those left unimmunized, the best protection was provided by the targeted DNA vaccine. We propose that targeting antigens to antigen-presenting cells offers a generic strategy for enhancing the efficacy of DNA vaccines.

Gas chromatographic determination of volatile congeners in spirit drinks: interlaboratory study

An interlaboratory study of a gas chromatographic (GC) method for the determination of volatile congeners in spirit drinks was conducted; 31 laboratories from 8 countries took part in the study. The method uses GC with flame ionization detection and incorporates several quality control measures which permit the choice of chromatographic system and conditions to be selected by the user. Spirit drink samples were prepared and sent to participants as 10 blind duplicate or split-level test materials for the determination of 1,1-diethoxyethane (acetal), 2-methylbutan-1-ol (active amyl alcohol), 3-methylbutan-1-ol (isoamyl alcohol), methanol (methyl alcohol), ethyl ethanoate (ethyl acetate), butan-1-ol (n-butanol), butan-2-ol (sec-butanol), 2-methylpropan-1-ol (isobutyl alcohol), propan-1-ol (n-propanol), and ethanal (acetaldehyde). The precision of the method for 9 of the 10 analytes was well within the range predicted by the Horwitz equation. The precision of the most volatile analyte, ethanal, was just above statistically predicted levels. This method is recommended for official regulatory purposes.

Distinct physiologic and neuronal responses to decreased leptin and mild hyperleptinemia

Leptin acts on specific populations of hypothalamic neurons to regulate feeding behavior, energy expenditure, and neuroendocrine function. It is not known, however, whether the same neural circuits mediate leptin action across its full biologic dose-response curve, which extends over a broad range, from low levels seen during starvation to high levels characteristic of obesity. Here, we show that the characteristic fall in leptin with fasting causes a rise in neuropeptide Y (NPY) messenger RNA (mRNA), as well as a fall in POMC and cocaine and amphetamine-regulated transcript (CART) mRNAs. Sc infusion of leptin sufficient to maintain plasma levels within the physiologic range during the fast prevents changes in the expression of these peptides, as well as changes in neuroendocrine function, demonstrating that multiple neural circuits are highly sensitive to small changes in leptin within its low physiologic range. In contrast, a modest elevation of plasma leptin above the normal fed range by constant sc infusion, which produced marked reduction in food intake and body weight, decreased NPY mRNA in the arcuate hypothalamic nucleus but did not affect the levels of mRNAs encoding the anorexigenic peptides alpha-MSH, CART or CRH. These results suggest that the dose response characteristics of leptin on hypothalamic target neurons at the level of mRNA expression are variable, with some neurons (e.g. NPY) responding across a broad dose range and others (e.g. POMC and CART) showing a limited response within the low range. These results further suggest that the central targets of leptin that mediate the transition from starvation to the fed state may be distinct from those that mediate the response to overfeeding and obesity.

Androgen receptor polymorphisms: association with prostate cancer risk, relapse and overall survival

Several reports have suggested that one or both of the trinucleotide repeat polymorphisms in the human androgen receptor (hAR) gene, (CAG)n coding for polyglutamine and (GGC)n coding for polyglycine, may be associated with prostate cancer risk; but no study has investigated their association with disease progression. We present here a study of both hAR trinucleotide repeat polymorphisms not only as they relate to the initial diagnosis but also as they are associated with disease progression after therapy. Lymphocyte DNA samples from 178 British Caucasian prostate cancer patients and 195 control individuals were genotyped by PCR for the (CAG)n and (GGC)n polymorphisms in hAR. Univariate Cox proportional hazard analysis indicated that stage, grade and GGC repeat length were individually significant factors associated with disease-free survival (DFS) and overall survival (OS). The relative risk (RR) of relapse for men with more than 16 GGC repeats was 1.74 (95% CI 1. 08-2.79) and of dying from any cause, 1.98 (1.13-3.45). Adjusting for stage and grade, GGC effects remained but were not significant (RR(DFS)= 1.60, p = 0.052; RR(OS)= 1.65, p = 0.088). The greatest effects were in stage T1-T2 (RR(DFS)= 3.56, 95% CI 1.13-11.21) and grade 1 (RR(DFS)= 6.47, 95% CI 0.57-72.8) tumours. No differences between patient and control allele distributions were found by odds-ratio analysis, nor were trends with stage or grade evident in the proportion of short CAG alleles. Non-significant trends with stage and grade were found in the proportion of short GGC alleles. The (GGC)n polymorphism in this population is a significant predictor of disease outcome. Since the (GGC)(n) effect is strongest in early-stage tumours, this marker may help forecast aggressive behaviour and could be used to identify those patients meriting more radical treatment.

Confirmation of genetic linkage between human systemic lupus erythematosus and chromosome 1q41

OBJECTIVE

Genetic susceptibility to systemic lupus erythematosus (SLE) is undoubtedly complex and, presumably, involves multiple loci. Linkage of SLE to D1S229 at chromosome 1q41 has been previously reported in a cohort of 52 affected sibpairs. The present study sought to confirm this reported linkage in an independent cohort of 127 extended multiplex SLE pedigrees containing 107 affected sibpairs.

METHODS

Genotype data were collected for D1S229 and 18 flanking microsatellite markers spanning chromosome 1q32-1q42. Analyses of genotype data included a model-based logarithm of odds (LOD) score approach, affected sibpair analyses, and transmission disequilibrium tests.

RESULTS

A maximum LOD score of 1.46 was found with D1S229 in a subgroup of 78 European American pedigrees, with additional support from multiple markers clustered around D1S229. Increased allele sharing in affected siblings was most significant at D1S2616, particularly in European Americans (P = 0.0005), followed by D1S229 (P = 0.002), D1S490 (P = 0.028), and D1S1605 (P = 0.037). Although linkage in a subgroup of 40 African American pedigrees was not suggested by the analyses of any marker tested in the chromosomal region surrounding D1S229, a maximum LOD score of 3.03 was found with D1S3462, mapped 15 centimorgans distal to D1S229.

CONCLUSION

Our linkage analysis results in European Americans at D1S229 are remarkably similar to those previously reported. That at least 1 genetic effect near this locus is important for susceptibility to lupus should now be generally accepted, and efforts to identify the gene are thereby justified.