Treatment of E2E2 homozygous familial dysbetalipoproteinemic subjects with gemfibrozil does not enhance the binding of their d < 1.019 lipoprotein fraction to the low-density lipoprotein receptor

DNA content analysis of formalin fixed paraffin embedded (FFPE) tissue permits determination of the influence of DNA content on the prognosis in cohorts of patients for whom the clinical outcome is known. Of key importance in such an analysis is the accuracy of DNA content determination. Variations in the quality of DNA histograms from FFPE tissues of different types prompted a comparative evaluation of the preparative methodology of FFPE soft tissue sarcomas for DNA flow cytometry. Following deparaffination and rehydration of fixed tissue, and prior to fluorochrome staining, tissue blocks of 15 DNA aneuploid soft tissue sarcomas were subjected to repeated experimental (time x concentration) enzyme exposures. The goal of these studies was to define the optimal tissue specific retrieval technique with the coefficient of variation, maintenance of DNA aneuploidy, and DNA index as endpoints. After optimizing the technique, the DNA content of 50 soft tissue neoplasms derived from FFPE specimens was compared to the corresponding fresh surgical tissue. The observed 14 percent error rate in the determination of DNA ploidy status suggest limited utility for FFPE tissue in prospective therapeutic trials of soft tissue sarcoma.     

Stress activated cytokines and the heart

The ability of myocardium to successfully compensate for, and adapt to, stress ultimately determines whether the heart will decompensate and fail, or whether it will instead maintain preserved function. Despite the importance of the myocardial response to environmental stress, very little is known with respect to the biochemical mechanisms that are responsible for mediating and integrating the stress response in the heart. In the present review we will summarize recent experimental material which suggests that cytokines that are expressed within the myocardium in response to a environment injury, namely tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1) and interleukin-6 (IL-6), may play an important role in initiating and integrating homeostatic responses within the heart. However, these 'stress-activated' cytokines all have the potential to produce cardiac decompensation when expressed at sufficiently high concentrations. Accordingly, the theme that will emerge from this discussion is that the short-term expression of stress-activated cytokines within the heart may provide the heart with an adaptive response to stress, whereas long-term expression of these molecules may be frankly maladaptive by producing cardiac decompensation.     

Transneuronal pathways to the vestibulocerebellum

The alpha-herpes virus (pseudorabies, PRV) was used to observe central nervous system (CNS) pathways associated with the vestibulocerebellar system. Retrograde transneuronal migration of alpha-herpes virions from specific lobules of the gerbil and rat vestibulo-cerebellar cortex was detected immunohistochemically. Using a time series analysis, progression of infection along polyneuronal cerebellar afferent pathways was examined. Pressure injections of > 20 nanoliters of a 10(8) plaque forming units (pfu) per ml solution of virus were sufficient to initiate an infectious locus which resulted in labeled neurons in the inferior olivary subnuclei, vestibular nuclei, and their afferent cell groups in a progressive temporal fashion and in growing complexity with increasing incubation time. We show that climbing fibers and some other cerebellar afferent fibers transported the virus retrogradely from the cerebellum within 24 hours. One to three days after cerebellar infection discrete cell groups were labeled and appropriate laterality within crossed projections was preserved. Subsequent nuclei labeled with PRV after infection of the flocculus/paraflocculus, or nodulus/uvula, included the following: vestibular (e.g., z) and inferior olivary nuclei (e.g., dorsal cap), accessory oculomotor (e.g., Darkschewitsch n.) and accessory optic related nuclei, (e.g., the nucleus of the optic tract, and the medial terminal nucleus); noradrenergic, raphe, and reticular cell groups (e.g., locus coeruleus, dorsal raphe, raphe pontis, and the lateral reticular tract); other vestibulocerebellum sites, the periaqueductal gray, substantia nigra, hippocampus, thalamus and hypothalamus, amygdala, septal nuclei, and the frontal, cingulate, entorhinal, perirhinal, and insular cortices. However, there were differences in the resulting labeling between infection in either region. Double-labeling experiments revealed that vestibular efferent neurons are located adjacent to, but are not included among, flocculus-projecting supragenual neurons. PRV transport from the vestibular labyrinth and cervical muscles also resulted in CNS infections. Virus propagation in situ provides specific connectivity information based on the functional transport across synapses. The findings support and extend anatomical data regarding vestibulo-olivo-cerebellar pathways.     

Effects of azimilide dihydrochloride on circus movement atrial flutter in the canine sterile pericarditis model

INTRODUCTION: The effects of a Class III agent, azimilide dihydrochloride, on atrial flutter circuits were studies in a functional model of single loop reentrant atrial flutter using dogs, 3 to 5 days after production of sterile pericarditis. METHODS AND RESULTS: A computerized mapping system was used to construct activation maps from 138 to 222 epicardial sites in the right atrium. Doses of 3, 10, and 30 mg/kg i.v. azimilide dihydrochloride were analyzed in 8 dogs in which sustained atrial flutter lasting more than 30 minutes was induced by burst pacing. Atrial flutter was always due to single loop circus movement reentry in the lower right atrium. At 3 mg/kg, azimilide dihydrochloride terminated atrial flutter in 2 dogs; however, atrial flutter was reinduced. At 10 mg/kg, atrial flutter was terminated in all 8 dogs but was reinduced in 4 dogs with slower rate. At 30 mg/kg, atrial flutter was terminated in the remaining 4 dogs and could not be reinduced. Atrial flutter cycle length always increased prior to termination. Isochronal activation maps showed that the increase in cycle length was due to additional conduction delays in the slow zone of the reentrant circuit. The site of termination was always located within the slow conduction zone situated in the lower right atrium between the line of functional conduction block and the AV ring. Effective refractory periods (ERPs) were measured at selected sites in the slow zone and normal zone at twice diastolic threshold for the 10 mg/kg dose. Azimilide preferentially prolonged ERP in the slow zone (42.4 +/- 20.1 msec, mean +/- SD) compared with the normal zone (23.3 +/- 15.4 msec, P < 0.0001). The increase in cycle length corresponded with the increase in ERP in the slow zone. CONCLUSIONS: In a functional model of circus movement atrial flutter, azimilide dihydrochloride terminates and prevents reinduction of atrial flutter by a preferential increase in refractoriness leading to further conduction delay and conduction block in the slow zone of the functional reentrant circuit.     

Biochemistry of 1,3-butadiene metabolism and its relevance to 1,3-butadiene-induced carcinogenicity

Recently, the roles of specific P450 isoforms, myeloperoxidase (MPO), GSH-S-transferase and epoxide hydrolase in the metabolism of 1,3-butadiene, and its major oxidative metabolite, butadiene monoxide (BM), were investigated. The results provided evidence for P450s 2A6 and 2E1 being major catalysts of 1,3-butadiene oxidation in human liver microsomes. cDNA-expressed human P450s 2E1, 2A6, and 2C9 catalyzed BM oxidation to meso- and (+/-)-diepoxybutane (DEB), but the rates of BM oxidation in mouse, rat, or human liver microsomes were much lower than the rates of 1,3-butadiene oxidation in these tissues. Human MPO catalyzed 1,3-butadiene oxidation to BM, but MPO incubations with BM did not yield DEB. Rates of BM formation in mouse and human liver microsomes were similar and were nearly 3.4-fold higher than that obtained with rat liver microsomes. However, rat liver epoxide hydrolase activity was nearly 2-fold higher than that of mouse liver microsomes. Rat and mouse liver GSH-S-transferases exhibited similar BM conjugation kinetics, but rats excreted more BM-mercapturic acids compared to mice given low equimolar doses of BM. BM reacted with guanosine and adenosine to yield N7-, N2-, and N1-guanosinyl and N6-adenosinyl adducts, respectively. These results may contribute to a better understanding of the biochemical basis of 1,3-butadiene-induced carcinogenicity.     

Common errors in panoramic radiography of edentulous patients

PURPOSE: Instructions for patient positioning during panoramic radiography usually describe positioning dentate patients, and errors in patient positioning are commonly identified by distortion of the dentition. The purposes of this study were to identify common errors in panoramic radiography of edentulous patients, describe the image distortions that can be expected with positioning errors in edentulous patients, and review quality assurance methods that improve the diagnostic value of panoramic films. MATERIALS AND METHODS: Panoramic films were randomly selected from the inactive files of 75 edentulous patients seen at the dental school for complete denture construction. The radiographs were numbered and reviewed by a board-certified oral and maxillofacial radiologist trained to identify errors in panoramic radiography. RESULTS: Of the 75 panoramic radiographs examined, only 6 films (8.0%) were free of errors, and 67 films (89.3%) had one or more errors in patient positioning and 33 films (44.0%) had one or more technical errors. The most common positioning errors were positioning the chin too high (32 films, 41.3%) and positioning the patient too far forward (26 films, 34.7%). CONCLUSIONS: Without modification, manufacturer's instructions for positioning dentate patients during panoramic radiography may result in positioning errors on the panoramic radiographs of edentulous patients. Proper training and appropriate attention to detail while exposing and developing panoramic films are required to ensure maximum diagnostic benefits for edentulous patients.     

Clinical observations of metabolic changes occurring in renal transplant recipients receiving ketoconazole

Metabolism of cyclosporine is reduced by ketoconazole binding to the monooxygenase responsible for cyclosporine degradation. This isozyme of cytochrome P450, along with other similar monooxygenases, is involved in the regulation of the synthesis and degradation of important metabolic pathways of cholesterol. Monooxygenases throughout these pathways are inhibited by ketoconazole binding causing a decreased metabolism of calcitriol, bile acids, and steroid hormones, and can thereby potentiate altered lipid metabolism, bone metabolism, and weight status of transplant recipients. A group of renal transplant recipients taking ketoconazole (n=25) was compared with a matched cohort not receiving ketoconazole for metabolic changes during the first six months posttransplantation. Lower LDL cholesterol levels were seen in the ketoconazole group (109 +/- 8 mg/dl) than the no ketoconazole group (140 +/- 8 mg/dl) at one month but this difference was not sustained at six months. More bone loss occurred in the ketoconazole group as demonstrated by significant changes in bone density as well as a greater urinary appearance of bone collagen crosslink, deoxy-pyridinoline (29 +/- 4 nmol dpd/mmol creatinine and 18 +/- 4 at six months for the ketoconazole group versus the no ketoconazole group, respectively, P<0.05). Weight gain changes were different between the ketoconazole group and no ketoconazole group (6.4 +/- 1.4 kg versus 5.0 +/- 1.3 kg) at six months and an increased rate of weight gain over time in the ketoconazole group (0.02 kg/day at one month versus 0.05 kg/day at six months, P<0.007). Effectiveness of ketoconazole inhibition of cyclosporine is valuable, but inhibition of other metabolic pathways should be evaluated as well.     

Assessment of the mathematical issues involved in measuring the fractional synthesis rate of protein using the flooding dose technique

1. The fractional synthesis rate of protein is commonly measured by either the constant infusion method or the flooding dose method. The two methods often give different results. 2. An underlying assumption of the traditional flooding dose formula is that the protein synthesis rate is not stimulated by the flooding dose. A new formula for calculation of the fractional synthesis rate is derived with the alternative assumption that the protein synthesis rate is stimulated by an amount proportional to the change in the intracellular concentration of the infused amino acid. The alternative formula is: Fractional synthesis rate = [formula: see text] where EB and EF are the enrichments of bound and free amino acid, respectively (atom per cent excess), and C = 1-(EF/EI), where EI is the enrichment of the infusate. This approach defines the lowest possible value for the fractional synthesis rate. The traditional equation gives a maximal value for the fractional synthesis rate. 3. When data from the literature are considered, the fractional synthesis rate of muscle protein as calculated by the constant infusion technique falls between the values of fractional synthesis rate calculated by the two flooding dose formulae when leucine is the tracer, suggesting that a flooding dose of leucine exerts a stimulatory effect on the rate of protein synthesis, but that the increase is not as great as the increase in the intracellular concentration of leucine.(ABSTRACT TRUNCATED AT 250 WORDS)     

(+)-4-[2-[4-(8-Chloro-3,10-dibromo-6,11-dihydro-5H-benzo[5, 6]cyclohepta[1,2-b]- pyridin-11(R)-yl)-1-piperidinyl]-2-oxo-ethyl]-1-piperidinecarboxamid e (SCH-66336): a very potent farnesyl protein transferase inhibitor as a novel antitumor agent

We have previously shown that appropriate modification of the benzocycloheptapyridine tricyclic ring system can provide potent farnesyl protein transferase (FPT) inhibitors with good cellular activity. Our laboratories have also established that incorporation of either pyridinylacetyl N-oxide or 4-N-carboxamidopiperidinylacetyl moieties results in pharmacokinetically stable inhibitors that are orally efficacious in nude mice. We now demonstrate that further elaboration of the tricyclic ring system by introducing a bromine atom at the 7- or the 10-position of the 3-bromo-8-chlorotricyclic ring system provides compounds that have superior potency and selectivity in FPT inhibition. These compounds have good serum levels and half-lives when given orally to rodents and primates. In vitro and in vivo evaluation of a panel of these inhibitors has led to identification of 15 (SCH 66336) as a highly potent (IC50 = 1.9 nM) antitumor agent that is currently undergoing human clinical trials.