Phenotyping cytochromes P450 with monoclonal antibodies

Monoclonal antibodies (MAbs) to cytochrome P-450 isozymes can be used to phenotype tissues for epitope-specific cytochrome P-450 content. MAbs that inhibit specific cytochrome P-450 dependent drug or carcinogen reactions are useful tools for quantitative measurement of the individual or classes of cytochromes P-450 that catalyze these reactions. This method has been applied successfully to animal as well as human tissues. Radioimmunoassays based on MAbs have been developed and provide a rapid and efficient means for detecting cytochromes P-450 independent of functional enzyme activity. In addition, MAbs coupled to a Sepharose support can be used to immunopurify cytochromes P-450 in a procedure that is more rapid and efficient than conventional purification schemes. MAbs add a new dimension to analyses of cytochrome P-450 multiplicity and will find numerous applications in elucidation of the relationship between cytochrome P-450 phenotype and carcinogen or drug metabolism.

Degenerate noncollinear emission from a type I collinear parametric oscillator

Noncollinear emission occurs in a free running type I parametric oscillator beyond the theoretical tuning curve for collinear oscillation. The noncollinear emission is described in terms of the emission angle and the corresponding angle of divergence. Experimentally recorded single captures of the transverse profile for the noncollinear regime are presented. A theoretical description of the degenerate tuning is described to explain the noncollinear regime.

Circulatory responses to maternal hyperoxaemia and hypoxaemia assessed non-invasively in fetal sheep at 0.3-0.5 gestation in acute experiments

OBJECTIVES

To determine fetal haemodynamic responses to hyperoxaemia and hypoxaemia in early pregnancy.

DESIGN

Repeated measurements in acute experiments.

SETTING

Experimental physiology laboratory.

METHODS

Non-invasive Doppler ultrasound of the umbilical vein, ductus venosus, umbilical and common carotid arteries of 12 fetal lambs (0.27-0.56 gestation) during maternal hyperoxaemia and hypoxaemia under ketamine anaesthesia. The effect of gestational age, hyperoxaemia, and hypoxaemia were assessed based on analysis of variance for dependent measurements and P < or = 0.05 was considered significant. Differences between groups were considered significant if the 95% confidence interval did not include zero.

RESULTS

Gestational age had a significant effect on the blood velocity in the umbilical vein and ductus venosus. There were no circulatory changes during hyperoxaemia, but a simultaneous increase of pCO2 was an important confounder. However, hypoxaemia caused significantly reduced heart rate, reduced maximum and weighted mean blood velocity, and augmented pulsation in the umbilical vein. Hypoxaemia also caused reduced velocities in the ductus venosus (peak velocity during systole and minimum during diastole, and time-averaged velocity) and augmented pulsation of the flow velocity. Additionally, the pulsatility of blood flow increased in the umbilical artery and was reduced in the common carotid artery.

CONCLUSIONS

Maternal hypoxaemia in early pregnancy causes similar fetal circulatory responses to those in late pregnancy: bradycardia, reduced venous flow velocities, augmented pulsatility in veins and a redistributional flow velocity pattern of the umbilical and common carotid arteries.

Recombinant Neisseria meningitidis transferrin binding protein A protects against experimental meningococcal infection

To better characterize the vaccine potential of Neisseria meningitidis transferrin binding proteins (Tbps), we have overexpressed TbpA and TbpB from Neisseria meningitidis isolate K454 in Escherichia coli. The ability to bind human transferrin was retained by both recombinant proteins, enabling purification by affinity chromotography. The recombinant Tbps were evaluated individually and in combination in a mouse intraperitoneal-infection model to determine their ability to protect against meningococcal infection and to induce cross-reactive and bactericidal antibodies. For the first time, TbpA was found to afford protection against meningococcal challenge when administered as the sole immunogen. In contrast to the protection conferred by TbpB, this protection extended to a serogroup C isolate and strain B16B6, a serogroup B isolate with a lower-molecular-weight TbpB than that from strain K454. However, serum from a TbpB-immunized rabbit was found to be significantly more bactericidal than that from a TbpA-immunized animal. Our evidence demonstrates that TbpA used as a vaccine antigen may provide protection against a wider range of meningococcal strains than does TbpB alone. This protection appears not to be due to complement-mediated lysis and indicates that serum bactericidal activity may not always be the most appropriate predictor of efficacy for protein-based meningococcal vaccines.

Identification of parasitoses in a child burial from Adak Island (Central Aleutian Islands, Alaska)

Bothriocephalid (Diphyllobothrium pacificum) and Ascarid (Ascaris lumbricoides) eggs have been identified in a sample taken in the abdominal cavity of a child skeleton found in Zeto Point (ADK-011), an archaeological site on Adak Island in the Central Aleutian Islands (Alaska).

Model selection for a medical diagnostic decision support system: a breast cancer detection case

There are a number of different quantitative models that can be used in a medical diagnostic decision support system (MDSS) including parametric methods (linear discriminant analysis or logistic regression), non-parametric models (K nearest neighbor, or kernel density) and several neural network models. The complexity of the diagnostic task is thought to be one of the prime determinants of model selection. Unfortunately, there is no theory available to guide model selection. Practitioners are left to either choose a favorite model or to test a small subset using cross validation methods. This paper illustrates the use of a self-organizing map (SOM) to guide model selection for a breast cancer MDSS. The topological ordering properties of the SOM are used to define targets for an ideal accuracy level similar to a Bayes optimal level. These targets can then be used in model selection, variable reduction, parameter determination, and to assess the adequacy of the clinical measurement system. These ideas are applied to a successful model selection for a real-world breast cancer database. Diagnostic accuracy results are reported for individual models, for ensembles of neural networks, and for stacked predictors.

Apoptosis and proliferation in nongenotoxic carcinogenesis: species differences and role of PPARalpha

Peroxisome proliferators (PPs) are nongenotoxic rodent hepatocarcinogens that cause liver enlargement and hepatocarcinogenesis associated with peroxisome proliferation, induction of hepatocyte DNA synthesis and suppression of apoptosis. Acyl CoA oxidase (ACO) is a key enzyme of peroxisomal beta-oxidation and its transcriptional activation by PPs is often used as marker for the rodent response. PPs activate the peroxisome proliferator activated receptor-alpha, PPARalpha. Recent data suggest a role for tumour necrosis factor alpha (TNFalpha). This cytokine appears to be permissive for a PPARalpha-dependent growth response to PPs. Humans and guinea pigs appear to be nonresponsive to the adverse effects of PPs noted in rodents. These species differences can be attributed to reduced quantity of full length functional PPARalpha in human liver and evidence supports the presence of a truncated form of PPARalpha, hPPARalpha8/14 in human liver. In addition, species differences could be attributed to qualitative differences in the PPARalpha-mediated response because the promoter for human ACO differs in sequence and activity from the rat equivalent. These data contribute to our understanding of how chemicals may cause tumours in rodents and how this response may differ in humans.

Amniotic gas values and acid-base status during acute maternal hyperoxemia and hypoxemia in the early fetal sheep

OBJECTIVE

This study was undertaken to determine amniotic fluid gas values and acid-base balance during maternal hyperoxemia and hypoxemia in early pregnancy.

STUDY DESIGN

Anesthetized sheep (n = 12) in early and mid pregnancy (0.3 to 0.5 gestation) were subjected to hyperoxemia followed by hypoxemia. Amniotic fluid PO (2), pH, PCO (2), bicarbonate concentration, and base excess were monitored continuously with a multiparameter Paratrend (Diametrics Medical Inc, St Paul, Minn) sensor and compared between 0.3 and 0.5 gestation.

RESULTS

During maternal normoxemia all parameters were constant. At all gestational ages maternal hyperoxemia caused no changes apart from a rapid increase in amniotic fluid PO (2) (P <.001). Maternal hypoxemia led to a reduced amniotic fluid PO (2) (P <.001), whereas the PCO (2) and the bicarbonate concentration increased (P <.001). Changes in amniotic fluid gas values and acid-base balance were more pronounced at 0.3 gestation than at 0.5 gestation. Amniotic fluid Po(2) responded earlier to maternal hyperoxemia than to hypoxemia (9. 5 vs 14.3 minutes; P <.001). During hypoxemia maternal PaCO (2) changed faster than did amniotic fluid PCO (2) (P <.001).

CONCLUSIONS

Acute maternal hypoxemia during early pregnancy was quickly reflected in amniotic fluid gas values and acid-base balance, whereas hyperoxygenation induced the quickest changes in amniotic fluid PO (2). The metabolic effects of maternal hyperoxemia and hypoxemia were also more pronounced during early pregnancy than at mid pregnancy.

Chronic constipation management for institutionalized older adults

Bran's effectiveness in reducing the need for bowel medication for intermediate care patients was examined at a VA medical center in New York. Twelve older men with chronic constipation and bowel medication use were matched and randomized to receive either bran treatment or usual care (controls). After baseline assessment, six patients were given gradually increasing daily doses of a bran mixture. Results over a 4-month period showed that these patients completely discontinued oral laxative use and had an 80% reduction in total bowel medication use without adversely affecting bowel frequency. The six men who received usual care (controls) experienced no changes.

Improving diagnostic accuracy using a hierarchical neural network to model decision subtasks

A number of quantitative models including linear discriminant analysis, logistic regression, k nearest neighbor, kernel density, recursive partitioning, and neural networks are being used in medical diagnostic support systems to assist human decision-makers in disease diagnosis. This research investigates the decision accuracy of neural network models for the differential diagnosis of six erythematous-squamous diseases. Conditions where a hierarchical neural network model can increase diagnostic accuracy by partitioning the decision domain into subtasks that are easier to learn are specifically addressed. Self-organizing maps (SOM) are used to portray the 34 feature variables in a two dimensional plot that maintains topological ordering. The SOM identifies five inconsistent cases that are likely sources of error for the quantitative decision models; the lower bound for the diagnostic decision error based on five errors is 0.0140. The traditional application of the quantitative models cited above results in diagnostic error levels substantially greater than this target level. A two-stage hierarchical neural network is designed by combining a multilayer perceptron first stage and a mixture-of-experts second stage. The second stage mixture-of-experts neural network learns a subtask of the diagnostic decision, the discrimination between seborrheic dermatitis and pityriasis rosea. The diagnostic accuracy of the two stage neural network approaches the target performance established from the SOM with an error rate of 0.0159.

Outcome in children under 5 years of age with constipation: a prospective follow-up study

Constipation in the pre-school child is common and causes considerable distress to children and their parents. There is a lack of information regarding prognosis in this group of patients although some are clearly at risk of developing long-term difficulties with defaecation. We have previously reported characteristics of children under 5 years of age referred to hospital over a one-year period with idiopathic constipation. We now report outcome data after 18 months of follow-up in 41 of the original cohort of 42 children. We have also summarised what we regard as good practice in managing constipation in this age group. Eighteen months after initial outpatient assessment, the symptoms of constipation were reported to have resolved in 36 (88%), although seven of these were still needing regular laxative treatment. It was our subjective impression that the five children who apparently did not improve came from families that had a greater degree of psychosocial problems and where compliance with treatment was suspect. This study shows that with simple treatment measures and ongoing support, an optimistic prognosis can be given to families from the outset. The minority of pre-school children who do not improve may benefit from a more intensive psychological approach to management.

Suppression of apoptosis and induction of DNA synthesis in vitro by the phthalate plasticizers monoethylhexylphthalate (MEHP) and diisononylphthalate (DINP): a comparison of rat and human hepatocytes in vitro

Diethylhexylphthalate (DEHP) and diisononylphthalate (DINP) are plasticizers with many important commercial, industrial and medical applications. However, both DEHP and DINP are rodent peroxisome proliferators (PPs), a class of compounds that cause rodent liver tumours associated with peroxisome proliferation, induction of hepatic DNA synthesis and the suppression of apoptosis. Despite these effects in the rodent, humans appear to be nonresponsive to the adverse effects of PPs. Previously, we have shown that the fibrate hypolipidaemic peroxisome proliferator, nafenopin, induced DNA synthesis and suppressed apoptosis in rat but not in human hepatocytes. In this work, we have examined species differences in the response of rat and human hepatocytes to DEHP and DINP in vitro. In rat hepatocytes in vitro, both DINP and MEHP (a principle metabolite of DEHP and the proximal peroxisome proliferator) caused a concentration-dependent induction of DNA synthesis and suppression of both spontaneous and transforming growth factor beta1 (TGFbeta1)-induced apoptosis. Similarly, both MEHP and DINP caused a concentration-dependent induction of peroxisomal beta-oxidation although the response to DINP was less robust. In contrast to the pleiotropic response noted in rat hepatocytes, neither DINP nor MEHP caused an induction of beta-oxidation, stimulation of DNA synthesis and suppression of apoptosis in human hepatocytes cultured from three separate donors. These data provide evidence for species differences in the hepatic response to the phthalates DEHP and DINP, confirming that human hepatocytes appear to be refractory to the hepatocarcinogenic effects of PPs first noted in rodents.

Nosocomial candidaemias due to species other than Candida albicans in cancer patients. Aetiology, risk factors, and outcome of 45 episodes within 10 years in a single cancer institution

Forty-five cases of fungaemia due non-albicans Candida spp. (NAC) in a single National Cancer Institution within 10 years were analysed for aetiology, risk factors and outcome. There had been 12 cases of fungaemia that were due to C. krusei, 14 due to C. parapsilosis, 7 due to C. (T.) glabrata, 6 to C. tropicalis, 2 to C. guillermondii, 2 to C. lusitaniae, 1 to C. stellatoidea, and 1 to C. rugosa. Comparison of 45 NAC fungaemia with 75 episodes of C. albicans fungaemia revealed differences only in two risk factors: previous empiric therapy with amphotericin B (16.0 vs 2.2%, P<0.01) appeared more frequently in cases of C. albicans fungaemia, and prior prophylaxis with fluconazole (8.9 vs 0%, P<0.02) was conversely more frequently observed with NAC. The incidence of other risk factors, such as underlying disease, chemotherapy, antibiotic prophylaxis or therapy, treatment with corticosteroids, catheter insertion, mucositis, cytotoxic chemotherapy, and neutropenia, was similar in both groups. There was no difference either in attributable or in overall mortality between NAC and C. albicans fungaemia in our cancer patients.

Documented fungal infections after prophylaxis or therapy with wide spectrum antibiotics: relationship between certain fungal pathogens and particular antimicrobials?

Antibiotics are known to be one of the major risk factors for fungal infection. We investigated whether there was a relationship between particular documented fungal infections and therapeutically or prophylactically administered antimicrobials in 105 patients with fungemia or histologically proven invasive aspergillosis or fusariosis. Out of 105 patients, 82.9% received antimicrobials affecting anaerobic microbial gut flora such as: imipenem, vancomycin, ceftazidime, metronidazole, clindamycin or ampicillin-sulbactam. In addition, 44.5% of patients had received prophylaxis with ofloxacin. 31.5% of Candida albicans fungemias occurred despite empiric therapy with amphotericin B and 21.1% during prophylaxis with azoles. The incidence of C. albicans infections (fungemias) was significantly higher (58.9% vs 33.7%, p<0.04) in patients receiving antibiotics not affecting anaerobic gut flora such as ofloxacin, an aminoglycoside or azithromycin. On the other hand, patients treated with third generation cephalosporins, carbapenems, glycopeptides, and broad spectrum penicillins were more likely to develop proven invasive Aspergillus spp. infection (27.9% vs 5.3%, p<0.001) in comparison to those treated with antimicrobials which preserve anaerobic gut flora.

Aetiology and outcome in 53 cases of native valve staphylococcal endocarditis

Within the last 30 years the profile of infective endocarditis has altered considerably with regard to microbiological causation, clinical features, and natural history. A contributory factor has undoubtedly been the development of potent antibiotics and their sometimes indiscriminate use. The increase in intravenous drug abuse in urban centres, the use of immunosuppressive agents, and the use of prosthetic heart valves have also all contributed. Although cardiac surgery in the uninfected heart provides a perfect environment for infective endocarditis, the improved design of prosthetic valves and the enhanced long-term survival and decreased immediate operative risk, means that surgery is viewed as the best option in many cases. In a series of 53 cases of staphylococcal endocarditis from a national endocarditis survey, those risk factors which influenced outcome were analysed. Thirty out of 53 patients had predisposing heart disease. Mortality was 39.6%. Statistical analysis revealed that attributable mortality was significantly associated with skin infection, systemic embolisation, and inappropriate therapy. Interestingly, surgical treatment was associated with better outcome.

T cell-mediated and non-specific inflammatory mechanisms contribute to the skin pathology of HPV 16 E6E7 transgenic mice

One of three lines of mice transgenic for the E6 and E7 genes of human papillomavirus type 16 (HPV16) expressed from an alphaA-crystallin promoter also expresses the transgene ectopically in the skin. This line, designated alphaACE6E7#19, develops skin disease from 3 months of age, characterised by epidermal hyperplasia and eventual skin loss. Administration of complete Freund's adjuvant (CFA) to alphaACE6E7#19 mice, but not to non-transgenic littermate controls, induced local epidermal hyperplasia which was histologically similar to the spontaneously arising skin pathology. Local application of 2,4-dinitrochlorobenzene (DNCB) to DNCB-sensitised alphaACE6E7#19 mice, but not DNCB-sensitised controls, also induced hyperplasia. Treatment with cyclosporin A (CsA) or systemic depletion of CD4+ cells significantly reduced the incidence of skin disease. These data suggest that local inflammation, and cytokines produced by T helper cells, contribute to the induction of hyperplastic skin disease in alphaACE6E7#19 mice. Spontaneous skin disease with similar histological appearance, frequency, age of onset and severity in alphaACE6E7#19 mice was observed in scid-/- alphaACE6E7#19 mice, despite immune paresis. Antigen-specific immune responses and T-cell cytokines are therefore not necessary for the induction of skin disease. We propose that epidermal hyperplasia associated with HPV16 E6 and E7 expression in skin is accelerated by local secretion of pro-inflammatory cytokines, whose production can be enhanced by activated CD4+ T cells.

First paleoparasitological analysis of a midden in the Aleutian Islands (Alaska): results and limits

Excavations on Buldir Island, Aleutian Islands, Alaska, have revealed the remains of several features dated between the 13th and 17th centuries A.D. Soil from an open-air workshop, represented by 2 excavated pits, and a structure built of whale bones were sampled for evidence of parasites and microfloristic remains. Two groups of helminth eggs (Diphyllobothrium and Ankylostomidae) were identified in samples from the open-air pits; microfloristical remains were found in all samples. This is the first paleoparasitological analysis conducted on an Aleutian midden.

Biliary imaging by spiral CT cholangiography--a retrospective analysis

CT cholangiography employs spiral CT scanning after the administration of biliary contrast medium to generate three-dimensional images of the biliary tract. A retrospective review of 61 patients who had undergone CT cholangiography was performed to determine the technical efficacy and the clinical utility of the technique. The results of CT cholangiography were analysed retrospectively to determine technical success rate of the imaging procedure and to correlate imaging diagnosis with results of other diagnostic procedures and with clinical follow-up. 60 of the 61 examinations produced technically satisfactory images. 21 of these examinations showed bile duct abnormalities. (12 stones, 6 duct dilatation to papillary level, 2 post-operative strictures and 1 case of sclerosing cholangitis). The remaining 39 cases showed no bile duct abnormality. In 59 of the 60 cases, subsequent investigations and follow-up supported the CT cholangiographic diagnosis. CT cholangiography is a robust technique for imaging of the biliary tract and is a valuable addition to the battery of non-invasive biliary investigations.

Native valve staphylococcal endocarditis: etiology, risk factors and outcome in 53 cases

Fifty-three cases of staphylococcal endocarditis from a national endocarditis survey were analyzed for risk factors and outcome. Thirty of 53 patients had predisposing heart disease (39.6% rheumatic fever) but only 3 were on dialysis, only 2 had central venous catheter, only 2 intravenous drug abuse but 7 had prior cardiosurgery. Mortality was 39.6%. In analyzing risk factors for death, attributable mortality was significantly associated with skin infections (P < 0.05), embolization (P < 0.02), inappropriate therapy (P < 0.005) either because of too short therapy (P < 0.003) or wrong antibiotic combination (P < 0.01). Surgical therapy was associated with better outcome (4.8% deaths vs. 31.2% survivors, P < 0.04).