The role of xenobiotic metabolizing enzymes in arylamine toxicity and carcinogenesis: functional and localization studies

Familial apolipoprotein C-II (apo C-II) deficiency is an autosomal recessive genetic disorder characterized by fasting hypertriglyceridemia and accumulation of chylomicrons in the plasma. To elucidate the genetic defect, the apo C-II gene of a neonatal Japanese patient (C-IITokyo) was analyzed. Nucleotide sequence analysis showed a G+1 to C transversion at the donor splice site of intron 2 (INT2 G+1 to C). Restriction fragment length polymorphism analyses of the patient's family members with Hph I showed that the patient was homozygous and the parents were heterozygous for the INT2 G+1 to C mutation. Although consanguinity could not be demonstrated, haplotype analysis of the C-II gene revealed the identity of the patient's alleles on the mutation, suggesting that the parents had a common Japanese ancestor. Sequence analysis of the patient's cDNA isolated from peripheral blood lymphocytes revealed that the INT2 G+1 to C mutation causes skipping of exon 2, which encodes the initiation codon, and results in deficiency of apo C-II proteins. The outstanding feature of our patient was that he showed severe hypertriglyceridemia beginning in the neonatal period, a feature not reported in a case of apo C-II deficiency (C-IIHamburg) with the same mutation as our patient. A previous report of another case of apo C-II deficiency (C-IIToronto) suggested that the apo E4 isoform is associated with higher levels of plasma triglycerides in subjects heterozygous for the apo C-II mutation. Determination of the apo E isoform of our patient revealed that apo E4 was coinherited with the INT2 G+1 to C mutation, whereas the apo E isoform has been reported to be E2/3 in C-IIHamburg. We speculate that apo E4/4 aggravated the hypertriglyceridemia in our patient with apo C-II deficiency.     

Intergroup relations: insights from a theoretically integrative approach

In social psychology, specific research traditions, which often spring up in response to external events or social problems, tend to perpetuate the theoretical assumptions and methodological approaches with which they began. As a result, theories and methods that have proven powerful in 1 topic area are often not applied in other areas, even to conceptually similar issues. The authors adopt a theoretically integrative approach to the topic of intergroup relations. Theories and empirical approaches from the domains of attitudes, impression formation, the self, personal relationships, and norms offer many new insights into problematic issues, such as repeated findings of dissociations among stereotyping, prejudice, and discrimination. This integrative approach not only promises new theoretical advances, but also suggests numerous potential practical approaches to limiting or reducing destructive patterns of intergroup relations.     

Gene therapy with HSP72 is neuroprotective in rat models of stroke and epilepsy

Brain areas damaged by stroke and seizures express high levels of the 72-kd heat shock protein (HSP72). Whether HSP72 represents merely a marker of stress or plays a role in improving neuron survival in these cases has been debated. Some induced tolerance experiments have provided correlative evidence for a neuroprotective effect, and others have documented neuroprotection in the absence of HSP72 synthesis. We report that gene transfer therapy with defective herpes simplex virus vectors overexpressing hsp72 improves neuron survival against focal cerebral ischemia and systemic kainic acid administration. HSP72 overexpression improved striatal neuron survival from 62.3 to 95.4% in rats subjected to 1 hour of middle cerebral artery occlusion, and improved survival of hippocampal dentate gyrus neurons after systemic kainic acid administration, from 21.9 to 64.4%. We conclude that HSP72 may participate in processes that enhance neuron survival during transient focal cerebral ischemia and excitotoxin-induced seizures.     

Sleep-promoting effects of melatonin: at what dose, in whom, under what conditions, and by what mechanisms?

Hydrocodone is a semisynthetic opioid with analgesic and antitussive properties qualitatively similar to other opioid agonists. Ibuprofen is a nonsteroidal antiinflammatory agent with analgesic and antipyretic activity and is an effective, primarily peripheral-acting antiinflammatory analgesic. The objective of this clinical trial was to determine the additive analgesic effect of the combination of 15 mg hydrocodone bitartrate with 400 mg ibuprofen, relative to 400 mg ibuprofen alone and placebo, in the treatment of postoperative pain. The single-dose analgesic efficacy of the combination of hydrocodone bitartrate with ibuprofen was compared with ibuprofen alone and placebo in 120 patients with moderate or severe postoperative pain after abdominal surgery. Analgesia was measured during the 6-hour period after dosing based on onset of relief, hourly and summary variables, and duration of effect. A significantly greater proportion of patients treated with the hydrocodone/ibuprofen combination reported onset of relief compared with ibuprofen or placebo; however, the distribution functions for time to onset of relief did not differ among treatments. Hydrocodone with ibuprofen and ibuprofen alone were significantly more effective than placebo for all measures of analgesia. The combination of hydrocodone with ibuprofen was significantly superior to ibuprofen for all hourly analgesic evaluations, weighted sum of pain intensity differences (SPID), total pain relief (TOTPAR), and global rating of study medication. No patients in the hydrocodone with ibuprofen group required analgesic remedication during the 6-hour study period, compared with 25% and 82% in the ibuprofen and placebo groups, respectively. The analgesic superiority of 15 mg hydrocodone bitartrate combined with 400 mg ibuprofen compared with 400 mg ibuprofen alone was demonstrated across many efficacy variables.     

PTEN/MMAC1/TEP1 suppresses the tumorigenicity and induces G1 cell cycle arrest in human glioblastoma cells

PTEN/MMAC1/TEP1 is a tumor suppressor that possesses intrinsic phosphatase activity. Deletions or mutations of its encoding gene are associated with a variety of human cancers. However, very little is known about the molecular mechanisms by which this important tumor suppressor regulates cell growth. Here, we show that PTEN expression potently suppressed the growth and tumorigenicity of human glioblastoma U87MG cells. The growth suppression activity of PTEN was mediated by its ability to block cell cycle progression in the G1 phase. Such an arrest correlated with a significant increase of the cell cycle kinase inhibitor p27(KIP1) and a concomitant decrease in the activities of the G1 cyclin-dependent kinases. PTEN expression also led to the inhibition of Akt/protein kinase B, a serine-threonine kinase activated by the phosphatidylinositol 3-kinase (PI 3-kinase) signaling pathway. In addition, the effect of PTEN on p27(KIP1) and the cell cycle can be mimicked by treatment of U87MG cells with LY294002, a selective inhibitor of PI 3-kinase. Taken together, our studies suggest that the PTEN tumor suppressor modulates G1 cell cycle progression through negatively regulating the PI 3-kinase/Akt signaling pathway, and one critical target of this signaling process is the cyclin-dependent kinase inhibitor p27(KIP1).     

Structure and activity of the hairpin ribozyme in its natural junction conformation: effect of metal ions

The natural form of the hairpin ribozyme consists of a four-way RNA junction of which the single-stranded loop-carrying helices are adjacent arms. The junction can be regarded as providing a framework for constructing the active ribozyme, and the rate of cleavage can be modulated by changing the conformation of the junction. We find that the junction-based form of the hairpin ribozyme is active in magnesium, calcium, or strontium ions, but not in manganese, cadmium, or sodium ions. Using fluorescence resonance energy transfer experiments, we have investigated the global structure of the ribozyme. The basic folding of the construct is based on pairwise helical stacking, so that the two loop-carrying arms are located on opposite stacked helical pairs. In the presence of magnesium, calcium, or strontium ions, the junction of the ribozyme undergoes a rotation into a distorted antiparallel geometry, creating close physical contact between the two loops. Manganese ions induce the same global folding, but no catalytic activity; this change in global conformation is therefore necessary but not sufficient for catalytic activity. Fitting the dependence of the conformation on ionic concentration to a two-state model suggests that cooperative binding of two ions is required to bring about the folding. However, further ion binding is required for cleavage activity. Cobalt hexammine ions also bring about global folding, while spermidine generates a more symmetrical form of the antiparallel structure. Cadmium ions generate a different folded form, interpreted in terms of close loop-loop association while the junction is unfolded. Sodium ions were unable to induce any folding of the ribozyme, which remained slightly parallel. These results are consistent with a folding process induced by the binding of two group IIA metal ions, distributed between the junction and the loop interface.     

Neuropathological findings in eight children with cerebro-oculo-facio-skeletal (COFS) syndrome

Cerebro-oculo-facial-skeletal (COFS) syndrome is a rare autosomal recessive disorder with microcephaly, severe mental retardation, and death in childhood. The pathogenesis is unknown. Neuropathological features of 8 children with COFS syndrome are presented. Seven of the children, ranging in age from 36 weeks gestation to 5 years 8 months, are of North American aboriginal background from Manitoba, Canada. The eight child is a 3-year-old Caucasian male. In all children there was severe microencephaly and mild ventriculomegaly. Cerebral myelination appeared to be delayed in one infantile case. Swollen ubiquitinated granular cells appeared in the white matter shortly after birth. Older children displayed cortical neuron loss, patchy or diffuse absence of myelin and gliosis in the white matter, and pericapillary and parenchymal mineralization in the globus pallidus and to a lesser extent the putamen and cerebral cortex. The cerebellum of older children exhibited severe degenerative changes involving the internal granular layer and Purkinje cell layer. The neuropathological changes, previously not well documented, suggest that COFS syndrome is associated with a degenerative process that begins in utero and affects many brain cell types. Similarities to Cockayne syndrome are discussed.     

Nonylphenol ethoxylates, but not nonylphenol, are substrates of the human multidrug resistance P-glycoprotein

The frequency of drug-resistant human immunodeficiency virus type 1 (HIV-1) variants in virus populations not previously exposed to drug was determined in vitro by using HIV-1RF and the protease inhibitor SC-55389A. Two variants with single mutations responsible for drug resistance (V82A and N88S) were quantifiably isolated after only one round of replication, yielding a crude frequency estimate of at least 1 SC-55389A-resistant variant per 3.5 x 10(5) wild-type infectious units.     

Sensitivity of condition indices to changing density in a white-tailed deer population

The ways in which comprehensive condition profiles, incorporating morphometric, histologic, physiologic, and diet quality indices, responded to changes in density of a white-tailed deer (Odocoileus virginianus) population were examined. Changes in these condition indices were monitored in a northeastern Oklahoma deer herd as density declined from peaks of 80 and 72 deer/km2 in 1989 and 1990 (high-density) to lows of 39 and 41 deer/km2 in 1991 and 1992 (reduced-density), respectively. Compared to a reference population (6 deer/km2), deer sampled during high-density exhibited classic signs of nutritional stress such as low body and visceral organ masses (except elevated adrenal gland mass), low fecal nitrogen levels, reduced concentrations of serum albumin, elevated serum creatinine concentrations, and a high prevalence of parasitic infections. Although density declined by one half over the 4-yr study, gross indices of condition (in particular body mass and size) remained largely unchanged. However, selected organ masses, serum albumin and non-protein nitrogen constituents, and fecal nitrogen indices reflected improvements in nutritional status with reductions in density. Many commonly used indices of deer condition (fat reserves, hematocrit, total serum protein, and blood urea nitrogen) were not responsive to fluctuations in density.     

Regulation of porcine granulosa cell steroidogenic acute regulatory protein (StAR) by insulin-like growth factor I: synergism with follicle-stimulating hormone or protein kinase A agonist

The transfer of cholesterol from the outer to the inner mitochondrial membrane, where side-chain cleavage occurs to form pregnenolone, is a crucial event in the regulation of steroidogenesis and recently has been demonstrated to be mediated by steroidogenic acute regulatory protein (StAR). We generated a partial porcine StAR complementary DNA (280 bp) by RT-PCR and used the corresponding antisense riboprobe to quantify the control of StAR gene expression by FSH and insulin-like growth factor I (IGF-I) in hormonally responsive swine granulosa cells, which typically manifest synergistic steroidogenic stimulation by these two dominant intrafollicular regulators. RNase protection assays were implemented to investigate the time course of the actions of FSH (100 ng/ml), IGF-I (100 ng/ml), and FSH plus IGF-I on StAR messenger RNA accumulation in serum-free cultures granulosa cells. Treatment with FSH (1.6-fold) or IGF-I (2.7-fold) alone had a small but consistent stimulatory effect on StAR message accumulation (corrected for 18S ribosomal RNA in each lane) at 48 h, whereas only IGF-I stimulated StAR protein expression (at least 6-fold as assessed by Western blot). Notably, the combined effect of FSH plus IGF-I was strongly synergistic and already significant by 24 h and maximal at 48 h (P < 0.001). Protein kinase A agonist, 8-bromoadenosine 3',5'-cAMP (8-bromo-cAMP) (1 mM) alone elicited a 3.5-fold increase in StAR message and more than 3.7-fold increase in StAR protein expression by 48 h. The combination of IGF-I and FSH or 8-bromo-cAMP evoked a 26- to 40-fold (P < 0.001) synergistic rise in StAR message accumulation. StAR protein also showed a similar synergistic pattern of expression driven by IGF-I and FSH or 8-bromo-cAMP, namely a greater than 56- to 60-fold increase. In summary, two distinct first messenger regulatory molecules, FSH and IGF-I, interact synergistically to induce amplification of StAR messenger RNA and protein expression in serum-free monolayer cultures of immature (swine) granulosa cells.