Personal names and the attentional blink: a visual "cocktail party" effect

Four experiments were carried out to investigate an early- versus late-selection explanation for the attentional blink (AB). In both Experiments 1 and 2, 3 groups of participants were required to identify a noun (Experiment 1) or a name (Experiment 2) target (experimental conditions) and then to identify the presence or absence of a 2nd target (probe), which was their own name, another name, or a specified noun from among a noun distractor stream (Experiment 1) or a name distractor stream (Experiment 2). The conclusions drawn are that individuals do not experience an AB for their own names but do for either other names or nouns. In Experiments 3 and 4, either the participant's own name or another name was presented, as the target and as the item that immediately followed the target, respectively. An AB effect was revealed in both experimental conditions. The results of these experiments are interpreted as support for a late-selection interference account of the AB.

Cutaneous xenobiotic metabolism: glycine conjugation in human and rat keratinocytes

Glycine conjugation is an important route of metabolism and detoxication of carboxylic acids in the liver. In this paper the in vitro cutaneous metabolism of [carboxyl-14C]benzoic acid to its glycine conjugate hippuric acid in rat and human skin is reported. Cutaneous glycine conjugation was studied in F344 rat and human epidermal keratinocytes using two systems: (1) freshly isolated keratinocytes in suspension and (2) primary keratinocyte cultures. For comparative purposes, studies were also carried out in freshly isolated and cultured F344 rat hepatocytes. After incubation of 5 x 10(6) cells with 1 microM benzoic acid at 37 degrees C for 8 hr, no glycine conjugation was observed in rat and human keratinocyte suspensions, with greater than 98% of the radioactivity recovered as the parent compound. In contrast, cultured keratinocytes exhibited glycine conjugation, with 10.9 +/- 1.0% (mean SEM, n = 3) and 2.1 +/- 0.6% (mean SEM, n = 3) conversion to hippuric acid at 8 hr in rat and human cells, respectively. Tissue-specific differences in metabolism were observed, with conjugation in hepatocytes significantly greater (P < 0.05) than in keratinocytes at all times up to 8 hr. After incubation of benzoic acid with cultured hepatocytes for 8 hr, more than 98% of the of the radioactivity was recovered as the glycine conjugate. These studies indicate that rat and human skin possesses low, but demonstrable, glycine-conjugating activity, and that keratinocytes in primary culture may provide a better system than freshly isolated cell suspensions for studying such activity.

Cinnamyl anthranilate causes coinduction of hepatic microsomal and peroxisomal enzymes in mouse but not rat

Cinnamyl anthranilate is a synthetic food flavoring and fragrance agent, formerly used at low levels. Although it is not genotoxic, very high doses have been shown to cause liver tumors in mice but not rats. In this report we characterize hepatic changes brought about by cinnamyl anthranilate in rats and mice. Groups of male CD1 mice and Fischer 344 rats received 0, 100, or 1000 mg/kg cinnamyl anthranilate by intraperitoneal injection daily for 3 days. After euthanization on the 4th day, plasma lipids and relative liver weight, tissue DNA, the peroxisome marker CN(-)-insensitive palmitoyl-CoA oxidation, cytochrome P450, microsomal lauric acid hydroxylation, aminopyrine N-demethylase and ethoxyresorufin O-deethylase, bilirubin UDP-glucuronosyltransferase, microsomal and cytosolic epoxide hydrolase, and the peroxisome/mitochondria ratio in liver sections were monitored. In mice a pattern of change pointing to peroxisomal proliferation was seen at both doses of cinnamyl anthranilate, but in rats fewer and smaller changes were seen with little or no evidence of peroxisomal proliferation at the doses used. Groups of male CD1 mice were given 0-200 mg/kg cinnamyl anthranilate daily for 3 days. At doses of 20 mg/kg and above, there were dose-dependent increases in relative liver weight, total cytochrome P450, and CN(-)-insensitive palmitoyl-CoA oxidation. The hepatic effects of cinnamyl anthranilate are apparently due to the intact ester, since neither its expected metabolites alone nor an equimolar mixture of the hydrolysis products, cinnamyl alcohol and anthranilic acid, had any significant effect on the weight or marker enzyme content of mouse liver. The data are discussed in relation to the species specificity of the hepatocarcinogenicity of cinnamyl anthranilate and to metabolic studies in rats and mice. It is suggested that in mice, peroxisomal proliferation occurs only at doses high enough to prevent complete metabolic hydrolysis.

Cryopreservation of rat and mouse hepatocytes. I. Comparative viability studies

We have compared the viability of cultures of cryopreserved (CP) rat and mouse hepatocytes with fresh cells with respect to their attachment efficiency, uptake of neutral red (NR), 2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carbo xyanilide xyanilide inner salt (XTT) metabolism, and ability to synthesize new proteins. Total recovery of rat hepatocytes after cryopreservation was 42.1 +/- 18.0%, with high viability (82.3 +/- 7.8%, as determined by trypan blue exclusion). These cells had significantly lower attachment efficiencies than fresh cells over 72 hr in culture. Viability of CP rat hepatocyte cultures was lower than fresh cell cultures, but was constant throughout 72 hr (approximately 68%). Total recovery of CP mouse hepatocytes (postthaw viability = 85.4 +/- 6.8%) was 53.6 +/- 14.7%. CP and fresh mouse hepatocyte cultures had similar attachment efficiencies and viabilities. NR uptake by CP rat hepatocyte cultures was significantly higher than in fresh cells at 48 and 72 hr after plating (400% and 810% of fresh cells, respectively). In contrast, CP mouse hepatocytes, which did not detach significantly in culture, took up NR to the same extent as fresh cells. The rate of NR uptake into rat and mouse hepatocytes, cultured for 24 hr, was unaltered by cryo-preservation. XTT metabolism by hepatocytes from either species was not affected by cryopreservation. Protein synthesis over 72 hr, as measured by incorporation of [3H]leucine, was lower in CP cultures than in fresh cells (CP rat hepatocyte protein synthetic activity was 32.3 +/- 6.8% of fresh, and CP mouse hepatocyte protein synthetic activity was 49.0 +/- 10.1% of fresh). Protein synthesis did not alter over 72 hr culture.

Desflurane and isoflurane increase lumbar cerebrospinal fluid pressure in normocapnic patients undergoing transsphenoidal hypophysectomy

BACKGROUND

Rapid emergence from anesthesia makes desflurane an attractive choice as an anesthetic for patients having neurosurgery. However, the data on the effect of desflurane on intracranial pressure in humans are still limited and inconclusive. The authors hypothesized that isoflurane and desflurane increase intracranial pressure compared with propofol.

METHODS

Anesthesia was induced with intravenous fentanyl and propofol in 30 patients having transsphenoidal hypophysectomy with no evidence of mass effect, and it was maintained with 70% nitrous oxide in oxygen and a continuous 100 micrograms.kg-2.min-1 infusion of propofol. Patients were assigned to three groups randomized to receive only continued propofol infusion (n = 10), desflurane (n = 10), or isoflurane (n = 10) for 20 min. During the 20-min study period, each patient in the desflurane and isoflurane groups received, in random order, two concentrations (0.5 minimum alveolar concentration [MAC] and 1.0 MAC end-tidal) of desflurane or isoflurane for 10 min each. Lumbar cerebrospinal fluid (CSF) pressure, blood pressure, heart rate, and anesthetic concentrations were monitored continuously.

RESULTS

Lumbar CSF pressure increased significantly in all patients receiving desflurane or isoflurane. Lumbar CSF pressure increased by 5 +/- 3 mmHg at 1-MAC concentrations of desflurane and by 4 +/- 2 mmHg at 1-MAC concentrations of isoflurane. Cerebral perfusion pressure decreased by 12 +/- 10 mmHg at 1-MAC concentrations of desflurane and by 15 +/- 10 mmHg at 1-MAC concentrations of isoflurane. Heart rate increased by 7 +/- 9 bpm with 0.5 MAC desflurane and by 8 +/- 7 bpm with 1.0 MAC desflurane, and by 5 +/- 11 bpm with 1.0 MAC isoflurane. Systolic blood pressure decreased in all but the patients receiving 1.0 MAC desflurane. To maintain blood pressure within predetermined limits, phenylephrine was administered to six of ten patients in the isoflurane group (range, 25 to 600 micrograms), two of ten patients in the desflurane group (range, 200 to 500 micrograms), and in no patients in the propofol group. Lumbar CSF pressure, heart rate, and systolic blood pressure did not change in the propofol group.

CONCLUSION

Desflurane and isoflurane, at 0.5 and 1.0 MAC, increase lumbar CSF pressure.

Cryopreservation of rat and mouse hepatocytes. II. Assessment of metabolic capacity using testosterone metabolism

Cryopreservation of hepatocytes is widely used, but to validate the use of cryopreserved (CP) hepatocytes in metabolic studies, CP cells must compare favorably with fresh cell activities. We have assessed the metabolic capacity of fresh and CP rat and mouse hepatocytes in primary culture. Total cytochrome P450 (P450) contents and metabolism of testosterone were measured up to 72 hr in culture. At 0 hr, total P approximately 450 in CP rat hepatocytes was 102.5 +/- 32.8 pmol/10(6) cells, compared with fresh rat hepatocytes that had 148.2 +/- 75.7 pmol/10(6) cells. The P450 contents of mouse hepatocytes were also unaltered by cryopreservation (176.7 +/- 56.0 pmol/ 10(6) fresh cells; 196.4 +/- 59.9 pmol/10(6) CP cells). There were no significant differences in the total P450 contents of fresh and CP rat and mouse cell cultures with time over 72 hr in culture. The overall metabolism of testosterone was lower in CP suspensions than in freshly isolated hepatocytes. When CP hepatocyte suspensions were permeabilized (with digitonin) and incubated with NADPH and ATP, testosterone metabolism was significantly increased. Testosterone hydroxylase activities (16 alpha-, 6 beta-, 2 alpha-, and 7 alpha-hydroxylase) were equivalent in fresh and CP rat hepatocytes over 72 hr in culture. There was a marked and sustained loss of 6 beta-hydroxylase activity in CP mouse hepatocyte cultures, compared with fresh hepatocytes throughout 72 hr in culture (436.9 +/- 118.0 pmol/min/10(6) cells and 37.3 +/- 41.0 pmol/min/10(6) cells at 72 hr in fresh and CP mouse hepatocytes, respectively). The total metabolism of testosterone was, however, unaffected because 16 alpha-hydroxylase activity increased in CP mouse hepatocytes (475.4 +/- 80.8 pmol/min/10(6) CP cells, compared with 148.7 +/- 39.4 pmol/min/10(6) fresh cells).

Pathways of metabolism of [1'-14C]-trans-anethole in the rat and mouse

This study describes the metabolic fate of trans-4'-methoxyprop-[1-14C]enylbenzene, the natural flavor compound trans-anethole, in rats and mice given single doses of 250 mg/kg body weight. In both rats and mice, an essentially quantitative (> 95% of dose) recovery of 14C was obtained with the majority in the 0-24 hr urine. Separation and identification of 18 urinary anethole metabolites were achieved by radio-HPLC, chemical derivatization, and GC/ MS. Anethole undergoes three primary oxidation pathways-O-demethylation, omega-side chain oxidation, and side chain epoxidation-followed by a variety of secondary pathways of oxidation and hydration, the products of which are extensively conjugated with sulfate, glucuronic acid, glycine, and glutathione. A novel major metabolite has been characterized in the rat, apparently originating from conjugation of the epoxide with glutathione, namely S-[1-(4'-methoxyphenyl)-2-hydroxypropane]-N-acetylcysteine. These metabolites are discussed in terms of the pathways responsible for and the toxicological consequences of their formation.

Hyperthyroidism during pregnancy: nursing care issues

Untreated hyperthyroidism during pregnancy is associated with a high incidence of maternal and fetal complications. The perinatal nurse needs knowledge of the pathophysiology of this condition to implement a care plan. Antithyroid medications are used to restore the patient's normal thyroid function. Ongoing evaluation of clinical and laboratory data assists the nurse in recognizing the development and implementation of interventions for complications, such as thyroid crisis and heart failure, in the pregnant patient.

Immunochemical detection of covalently modified protein adducts in livers of rats treated with methyleugenol

Methyleugenol is an allylbenzene food flavoring which has been shown to form DNA and protein adducts, and to cause hepatotoxicity and carcinogenicity in rodents. In order to investigate the nature of the protein adducts, specific antisera were raised by immunizing rabbits with conjugates prepared by coupling 1'-acetoxymethyleugenol, or its acidic congener 3,4-dimethoxycinnamic acid, to rabbit serum albumin (RSA). These polyclonal antisera were shown by enzyme linked immunosorbent assay (ELISA) to contain antibodies which recognized the 3,4-dimethoxyphenyl ring portion of methyleugenol. Analysis of livers from rats given methyleugenol i.p. for 5 days, at doses between 10 and 300 mg/kg/day, revealed dose-dependent formation of novel protein adducts which were recognized by the antisera. The adducts were detected by ELISA and by immunoblotting and were concentrated in the microsomal fraction, and were shown in inhibition studies to be derived from methyleugenol. A 44 kDa adduct was the only protein adduct detected in livers of rats given low loses of methyleugenol (10 or 30 mg/kg/day) and was the major adduct detected in rats given high doses of the compound (100 and 300 mg/kg/day). This adduct was solubilized when microsomal fractions were extracted using 0.1 M sodium carbonate, implying that it is a peripheral membrane protein. A pattern of protein adducts which mirrored the in vivo situation was generated when rat hepatocytes were incubated with 1'-hydroxymethyleugenol in vitro, but could not be reproduced in experiments undertaken using liver microsomes or postmitochondrial supernatants. These findings imply that generation of protein adducts in livers of rats given methyleugenol in vivo proceeds via the 1'-hydroxy metabolite and requires crucial cofactors, and/or structural features, which are present in intact hepatocytes but not in broken cell preparations and which remain to be defined.

Telephone follow-up after discharge from the hospital: does it make a difference?

Two systems of telephone follow-up of discharged patients were compared in this 3-month study. All medical and surgical patients on five nursing units of one acute care institution were included, yielding a sample of over 1,400 patients. One group of patients was called 2 to 3 days after discharge; another group received a brochure describing a nurse-run telephone service they could call. A third group of patients received no intervention. More than 90% of patients who were called had questions about self-care and recovery at home. Only nine patients initiated calls to the nurse telephone service. The three groups did not differ in patient satisfaction with health education or readmission rates within 30 days of discharge. This study suggests that patients have continued health education needs after discharge but are unlikely to actively seek needed information from a hospital-based telephone service.

Crystallization and preliminary X-ray analysis of brazzein, a new sweet protein

Brazzein is a sweet protein isolated from a wild African plant Pentadiplandra brazzeana. Brazzein is the smallest (molecular mass = 6473 Da) and the most water-soluble protein sweetener discovered so far and is highly thermostable. Crystals were grown by vapor diffusion using sodium sulfate as a precipitant. They belong to the tetragonal space group I4(1)22 with unit-cell parameters a = b = 61.4, c = 59.6 A and with one molecule in the asymmetric unit. The crystals diffract to 1.8 A resolution using synchrotron radiation.

Lack of influence of modulators of epoxide metabolism on the genotoxicity of trans-anethole in freshly isolated rat hepatocytes assessed with the unscheduled DNA synthesis assay

The aniseed food flavour trans-anethole was implicated as a weak hepatocarcinogen only in female Sprague Dawley-CD rats administered high doses (1% in the diet for 121 wk). However, this substance is apparently non-genotoxic in a range of test systems. Anethole is metabolized in the rat along three primary pathways, one of which is epoxidation across the double bond of the side-chain. The epoxides of a number of the alkenylbenzene family of food flavours, of which anethole is a member, are putative genotoxins, being bacterial mutagens but not mammalian carcinogens. The authors have previously shown that the cytotoxicity of anethole is enhanced when the cellular epoxide defence mechanisms of conjugation with reduced glutathione and hydration by cytosolic epoxide hydrolase are severely compromised. They now report, however, that modulation of epoxide metabolism in cultured cells by the same mechanisms fails to induce unscheduled DNA synthesis (UDS) by anethole nor was there a UDS response in hepatocytes of female rats dosed with anethole in vivo. The epoxide of anethole was synthesized for the first time in this investigation and tested directly. As expected, it was markedly cytotoxic but not genotoxic. Anethole epoxide has chemical characteristics that differ from those of other structurally similar epoxides being labile to hydrolysis in aqueous media at physiological pH and temperature. This gives greater relevance to tests of its genotoxicity after formation within the hepatocyte rather than by adding the epoxide extracellularly to the culture medium. The direct and indirect demonstration of the lack of induction of UDS by anethole epoxide provides further support for the hypothesis that marginal hepatocarcinogenicity observed in female rats given 1% anethole in the diet for 121 wk was not initiated by a genotoxic event.

Factors affecting the metabolism of cinnamyl anthranilate in the rat and mouse

The biological actions of cinnamyl anthranilate are dependent on both dose size and animal species. The present study aimed to examine metabolism as a possible source of explanation for these differences. [3-14C]Cinnamyl anthranilate was synthesized, injected ip into male Fischer 344 (F344) rats and CD-1 mice and urine and faeces collected for 3 days. The pattern of elimination of 14C was the same in both species, with the bulk of the administered material recovered in urine over the first 24 hr. Urinary metabolic profiles were compared by radioHPLC, which showed that the major radioactive excretion product in the rat was hippuric acid accompanied by smaller amounts of benzoic acid. In contrast, mouse urine contained relatively less hippuric acid, more benzoic acid and small amounts (approx. 3% of dose) of unchanged cinnamyl anthranilate. The effect of dose size on urinary metabolites produced by mice was examined using both 3-14C-labelled and unlabelled cinnamyl anthranilate, detected by fluorescence HPLC. Over a dose range of 5 to 250 mg/kg body weight administered ip it was found that at 5 mg/kg body weight no intact ester was excreted in urine whereas at 20 mg/kg body weight or above, the proportion present as the intact ester remained constant. Dietary administration to male and female B6C3F1 mice for 21 days over a dose range of 0 to 30,000 ppm revealed the same qualitative picture with no intact cinnamyl anthranilate detected in urine at or below 1000 ppm (equivalent to 100 mg/kg body weight). A study in human volunteers using a single oral dose of 250 mg failed to reveal any intact cinnamyl anthranilate in 0-24-hr urine. These data support the hypothesis that the peroxisome proliferating action of cinnamyl anthranilate, which is mediated by the intact ester, is manifest only at high doses in species in which its metabolism by hydrolysis is saturated, as a consequence of which the intact ester 'overflows' into urine.

Novel alterations in CDK1/cyclin B1 kinase complex formation occur during the acquisition of a polyploid DNA content

The pathways that regulate the S-phase events associated with the control of DNA replication are poorly understood. The bone marrow megakaryocytes are unique in that they leave the diploid (2C) state to differentiate, synthesizing 4 to 64 times the normal DNA content within a single nucleus, a process known as endomitosis. Human erythroleukemia (HEL) cells model this process, becoming polyploid during phorbol diester-induced megakaryocyte differentiation. The mitotic arrest occurring in these polyploid cells involves novel alterations in the cdk1/cyclin B1 complex: a marked reduction in cdk1 protein levels, and an elevated and sustained expression of cyclin B1. Endomitotic cells thus lack cdk1/cyclin B1-associated H1-histone kinase activity. Constitutive over-expression of cdk1 in endomitotic cells failed to re-initiate normal mitotic events even though cdk1 was present in a 10-fold excess. This was due to an inability of cyclin-B1 to physically associate with cdk1. Nonetheless, endomitotic cyclin B1 possesses immunoprecipitable H1-histone kinase activity, and specifically translocates to the nucleus. We conclude that mitosis is abrogated during endomitosis due to the absence of cdk1 and the failure to form M-phase promoting factor, resulting in a disassociation of mitosis from the completion of S-phase. Further studies on cyclin and its interacting proteins should be informative in understanding endomitosis and cell cycle control.

Importance of stereospecific bioanalytical monitoring in drug development

The role of the bioanalyst in the support of drug discovery and development is described with particular emphasis upon stereospecific assays for the individual optical isomers of chiral drugs. The significance of the stereochemical aspects of pharmacokinetics and drug metabolism in both preclinical and clinical development is summarized and illustrated with reference to the pharmacogenetic polymorphisms of drug oxidation existing in the human population. The significance of stereochemical considerations in drug metabolism and pharmacokinetics has recently become an issue for both the pharmaceutical industry and the regulatory authorities, driven to a great extent by recent developments in methodology for both the analytical and preparative resolution of racemic drug mixtures. Ths has led to the so-called 'racemate-versus-enantiomer' debate in recent years. The development of regulatory attitudes in the major jurisdictions of the world to the development of new drugs containing one or more chiral centres is outlined.

Needs and program strengths: perceptions of hospice volunteers

A state-wide survey was conducted of highly effective hospice volunteers who were questioned about their motivations for becoming a volunteer, training experience and needs, and reasons for continuing in the volunteer role. Needs identified included having a volunteer support group, on-going training opportunities, and opportunities for getting to know other volunteers better. Excellent training, belief in the hospice mission, the relationship with staff, feeling valued, and personal fulfillment were strengths and motivations to continue as a hospice volunteer. Findings from the study will be helpful to hospice staff who recruit, train, and support volunteers.

The efficacy, tolerability, and safety of 1200 mg/d of oxaprozin and 1500 mg/d of nabumetone in the treatment of patients with osteoarthritis of the knee

This 6-week, multicenter, double-masked, placebo-controlled study compared the efficacy, tolerability, and safety of the recommended starting dose of oxaprozin (1200 mg/d) and a 1500-mg/d dose of nabumetone in the treatment of patients with moderate-to-severe osteoarthritis (OA) of the knee. A total of 347 patients with a mean age of 61.1 years were randomized to receive oxaprozin (116 patients), nabumetone (115 patients), or placebo (116 patients). Adults of either sex who were older than 18 years of age were eligible for entry into the study, if they had had OA of the knee for at least 6 months. Efficacy variables included knee pain on weight bearing, knee pain on motion, patients' and physicians' global assessments of OA, pain intensity as measured on a visual analog scale, and time to walk 50 feet as quickly as possible. Efficacy variables were assessed at baseline and at weeks 1, 2, 4, and 6. Between-group differences in efficacy variables were evident by week 1. Mean improvements were significantly greater with oxaprozin than with placebo for all efficacy variables at all time periods, except knee pain on motion at weeks 2 and 4 and time to walk 50 feet at weeks 1, 2, and 4. Mean improvements were significantly greater with nabumetone than with placebo for all efficacy variables at all time periods, except the following: knee pain on weight bearing at weeks 2, 4 and 6; knee pain on motion at weeks 2 and 4; patients' global assessment at week 4; and pain intensity as measured on a visual analog scale at weeks 2 and 4. There were, however, no significant differences between oxaprozin and nabumetone in any of these efficacy variables. Adverse events were reported by 83 (71.6%) patients who took oxaprozin, by 80 (69.6%) patients who took nabumetone, and by 57 (49.1%) patients who took placebo. Adverse events were reported for significantly more patients taking oxaprozin or nabumetone than placebo. However, adverse events tended to be mild or moderate and rarely resulted in patients withdrawing from the study. Combined with the results of an earlier study, the results of this study showed that a 1500-mg/d dose of nabumetone, which is higher than the recommended starting dose of 1000 mg/d, is required for efficacy equivalent to that of the recommended starting dose of oxaprozin, 1200 mg/d, in relieving the symptoms of OA. Thus nabumetone may require dosage titration from the recommended starting dose. Oxaprozin and nabumetone were found to have similar tolerability profiles, as shown by adverse-event monitoring and withdrawal rates, as well as clinically similar safety profiles, as demonstrated by physical examinations, hematologic and biochemical laboratory testing, hemoccult testing, and adverse-event monitoring and symptom assessment.

Pharmacokinetics of the 5-hydroxytryptamine1A agonist 8-hydroxy-2-(N,N-di-n-propylamino)tetralin (8-OHDPAT) in the rat after intravenous and oral administration

1. Plasma levels of 3H and unchanged drug were measured in the non-anaesthetized male rat after intravenous (i.v.) or oral administration of (+/-)-(R,S)-[propyl-3H]-8-OHD-PAT, at three dose levels per route of administration. The excretion of conjugated metabolites in bile was also studied following i.v. administration. 2. For unchanged 8-OHDPAT following i.v. administration, terminal t1/2 was 1.56 +/- 0.01 h (mean +/- SD, n > or = 4), kelim 0.45 +/- 0.01 h-1, volume of distribution 0.14 +/- 0.02 litres and clearance 1.10 +/- 0.17 mlmin-1. After oral administration, terminal t1/2, kelim, apparent volume of distribution and clearance were essentially the same when bioavailability was taken into account. Neither dose size nor route of administration had any significant effect on either terminal t1/2 or kelim. Comparison of AUCs following i.v. and oral administration yielded a mean for absolute oral bioavailability of 2.60 +/- 0.24%. 3. Comparison of AUCB for total plasma 3H showed that the extent of absorption was 80.1%, indicating that the low oral bioavailability of 8-OHDPAT is due to first-pass metabolism, rather than poor absorption from the GI tract. 4. Following i.v. administration, irrespective of dose, some 10% of the 3H dose was excreted in the bile in 6 h, 8.5% as 8-OHDPAT-glucuronide and 1.5% as the glucuronide of the N-despropylated metabolite, 8-OHDPAT. The majority of the biliary excretion occurred within 3 h of dosing.

Interleukin-1 alpha upregulates tumor necrosis factor receptors expressed by a human bone marrow stromal cell strain: implications for cytokine redundancy and synergy

To explore the biochemical and physiologic basis of the overlapping effects of interleukin-1 alpha (IL-1 alpha) and tumor necrosis factor alpha (TNF-alpha) on myeloid cytokine production, we have studied the dynamics of granulocyte colony-stimulating factor (G-CSF) and granulocyte-monocyte colony-stimulating factor (GM-CSF) production as well as IL-1 receptor and TNF receptor expression in a clonally derived bone marrow stromal cell strain (CDCL). IL-1 alpha and TNF alpha act in a synergistic manner to stimulate G-CSF and GM-CSF production by CDCL, resulting in an increase in CSF secretion that is 250-fold greater than that observed with either cytokine alone. This synergism in protein secretion is paralleled by synergistic increases the steady-state level of GM- and G-CSF mRNA, with supra-additive levels achieved by 24 hours. Coincident with this synergistic induction of myeloid CSFs, treatment of CDCL cells with IL-1 alpha induces a 300% increase in the expression of TNF receptors. IL-1 alpha induction of TNF receptors reaches a peak after 6 hours and gradually returns to baseline level by 24 hours. IL-1 alpha does not affect TNF receptor ligand binding affinity. A kinetic study comparing IL-1/TNF synergistic induction of growth factor secretion with IL-1 alpha induction of TNF receptors shows that these events occur in parallel. In contrast with the induction of TNF receptors by IL-1 alpha, treatment with TNF alpha has no effect on either the number of IL-1 receptors expressed by CDCL cells or IL-1 receptor ligand binding affinity. Brief treatment of IL-1 alpha/TNF alpha-stimulated CDCL cells with cycloheximide before receptor induction reduces the synergistic increase in growth factor mRNA by 40% to 60% compared with cells not treated with CHX. Taken together, these results raise the possibility that IL-1 alpha cross-induction of TNF receptors may contribute to the biochemical mechanisms underlying the synergistic stimulation of G-CSF and GM-CSF production by IL-1 alpha and TNF alpha.

Intestinal site-dependent susceptibility to chronic indomethacin in the rat: a morphological and biochemical study

BACKGROUND

The cyclo-oxygenase inhibitor indomethacin induces a pattern of gastrointestinal injury in the rat that is site-dependent. This study compared the extent of injury to different regions of the rat intestine (small intestine, caecum and colon) with the corresponding changes in arachidonic acid metabolism in these areas, following long-term, low-dose indomethachin.

METHODS

Rats (eight per group) received either indomethacin (3 mg.kg/day) or control diet for either 6 or 12 weeks. At termination animals were bled, examined both macroscopically and microscopically for ulcers, and assayed for blood thromboxane B2, intestinal tissue prostaglandin E2 content and production of leukotriene B4. In a further eight animals luminal indomethacin concentrations from the small intestine, caecum and colon were measured following 6 weeks of chronic drug ingestion.

RESULTS

At 6 weeks, macroscopic ulcers were observed in 2/8 (small intestine), 3/8 (caecum) and 1/8 (colon) animals. The corresponding ratios at 12 weeks were 5/8, 8/8 and 0/8. In control animals, a site-dependent gradient of the prostaglandin E2 concentration was found. In indomethacin-dosed animals the intestinal prostaglandin E2 content was reduced significantly in the caecum at 6 weeks, and in all tissues at 12 weeks. An increased leukotriene B4 production was observed in the caecum only, at 12 weeks (P < 0.01), and the blood thromboxane B2 was reduced at both time points (P < 0.05).

CONCLUSION

There is a site-dependent gradient of the prostaglandin E2 concentration in the rat intestine. The rat caecum is particularly sensitive to long-term low-dose indomethacin, both in terms of chronic intestinal inflammation and changes in prostanoid metabolism. This site-dependent degree of injury may be associated with a local cyclo-oxygenase inhibition.

Comparison of the efficacy and safety of oxaprozin and nabumetone in the treatment of patients with osteoarthritis of the knee

This multicenter, 6-week, double-blind, placebo-controlled, parallel-group study compared the efficacy and safety of oxaprozin 1200 mg once daily with that of nabumetone 1000 mg once daily in patients with moderate-to-severe osteoarthritis (OA) of the knee. To be eligible, patients had to experience a flare of OA within 2 weeks of discontinuing their usual OA medication (nonsteroidal anti-inflammatory drug or analgesic). Eligible patients were assessed at baseline and then randomized to receive oxaprozin (n = 109), nabumetone (n = 110), or placebo (n = 109). Efficacy assessments were performed at weeks 1, 2, 4, and 6. Primary efficacy variables included knee pain on weight bearing, knee pain on motion, and patient's and physician's global assessments of OA. Secondary efficacy variables included pain intensity, time to walk 50 feet, and duration of morning stiffness. Safety was evaluated by use of routine laboratory analyses; physical examination at screening, baseline, and week 6 (or study termination); assessment of symptoms at baseline and at each visit; and testing stools for occult blood at screening and between week 4 and the final visit. Adverse events were monitored throughout the study. Between-group differences in efficacy variables were evident by week 1. The mean change in improvement from baseline with oxaprozin compared with placebo was statistically significant in favor of oxaprozin at weeks 1, 2, 4, and 6 for all primary efficacy variables. The mean change in improvement from baseline with nabumetone compared with placebo, however, was statistically significant only at week 1 for knee pain on motion, patient's global assessment, and physician's global assessment. The mean change in improvement from baseline was statistically significant (P < or = 0.035) in favor of oxaprozin versus nabumetone at weeks 2 and 6 for all four primary efficacy variables and also at week 4 for knee pain on motion. The incidence of adverse clinical events between treatment groups was not statistically significant. However, nine oxaprozin-treated patients had asymptomatic liver enzyme elevations reported as adverse events. Four of these patients had reversible elevations of aspartate aminotransferase and alanine aminotransferase greater than three times the upper limit of normal range (P < 0.05); two of these patients were taking other medications known to induce liver enzyme abnormalities. The study showed that oxaprozin 1200 mg once daily was statistically significantly more efficacious than nabumetone 1000 mg once daily for the treatment of patients with moderate-to-severe OA of the knee. Both drugs were clinically well tolerated.

Decontamination procedures after in vitro topical exposure of human and rat skin to 4,4'-methylenebis[2-chloroaniline] and 4,4'-methylenedianiline

4,4'-Methylenebis[2-chloroaniline] (MbOCA) and 4,4'-methylenedianiline (MDA) are widely used industrial chemicals classified as suspect human carcinogens. There is considerable occupational skin exposure to these compounds, and consequently, it is important to establish an efficient washing procedure after skin contamination. Four washing solutions were studied (100% ethanol, 100% water, 1 and 10% (v/v) aqueous soap) using fresh human and male F344 rat skin in flow-through diffusion cells. All solutions were equally effective at removing MbOCA and MDA from the surface of human skin, with 21-47% of the applied dose removed at 72 hr. In contrast, with rat skin 100% water and 1% soap solution were significantly less (p < 0.05) effective than 10% soap solution and 100% ethanol at removing MbOCA and MDA. Washing the skin surface at 3 or 30 min significantly reduced (p < 0.05) the absorption of MbOCA and MDA into and through human and rat skin at 72 hr by two- to threefold, compared with control unwashed skin. Washing the skin after this critical time point did not significantly reduce the absorption. These studies suggest that MbOCA and MDA are rapidly absorbed from the skin surface into the skin. Therefore, in order to reduce systemic exposure, the skin must be washed within the first 30 min after contamination has occurred. For human skin, the choice of washing solution employed was not as critical as the time of washing. This is in contrast to the rat, where the higher concentration soap and ethanol solutions were more effective for skin decontamination.

(-)-R-fenoprofen: formation of fenoprofenyl-coenzyme A by rat liver microsomes

The thioesterification of fenoprofen (FPF) by rat liver microsomes has been studied using an HPLC method enabling direct quantification of the FPF-CoA produced. Over the concentration range studied (5-400 microM), studies showed the participation of a single CoA ligase in the formation of FPF-CoA, in contrast with the involvement of several isozymes with different affinities, that has been found with ibuprofen (IPF). The Km for the reaction was dependent upon the presence of non-ionic detergent, a concentration of 0.05% Triton X-100 reducing the Km from 397 to 20 microM although the detergent had no effect on Vmax. The microsomal long-chain fatty acid CoA ligase was markedly enantioselective towards (-)-R-FPF and the formation of (-)-R-FP-CoA was inhibited by both the (+)-S enantiomer and palmitic acid.

Assessing the impact of stressors on performance: observations on levels of analyses

Applied researchers often are required to rely on limited laboratory studies to estimate the effects of various stressors on actual job performance. It can be difficult to select measures which lend themselves to implementation in laboratory settings while also providing sufficient capability to predict complex 'real-world' performance. Studies which employ simulations of operationally-relevant tasks and those which include the administration of basic cognitive tests are favored by many applications-oriented researchers. This is despite the fact that such a testing approach may limit sensitivity due to the requirements for extensive practice on these tasks in order to obtain stable results. Studies which use physiological assessments appear to be less readily accepted by applied researchers because of the difficulties in drawing a direct link between physiological indexes and operational performance. However, there are arguments to be made for the inclusion of physiological evaluations with the more traditional, performance-based measures. Data from three studies are cited here to support the value of using a multifaceted approach to the study of operationally-relevant stressors. Although these studies were not conducted to systematically investigate the relative merits of performance, cognitive, and physiological assessments, they do serve to highlight the fact that inclusion of all three types of tests tend to maximize the validity, interpretability, and sensitivity of applied research.

The pharmacokinetics and neuromuscular effects of rocuronium bromide in patients with liver disease

To determine the effect of liver disease on the pharmacokinetics of rocuronium, the authors administered 0.6 mg/kg (twice the ED95) to 10 patients with liver disease and compared these results to values in 10 healthy surgical patients. Anesthesia was induced with thiopental and maintained with isoflurane (0.9%-1.1% end-tidal concentration) and nitrous oxide (60%). Venous blood samples were obtained for 6 h after rocuronium injection and plasma concentrations were measured using gas chromatography. Pharmacokinetic differences between groups were determined using a population-based pharmacokinetic analysis (NONMEM). Hepatic impairment did not alter the plasma clearance of rocuronium (217 +/- 21.8 mL/min, mean +/- SE, for both groups), but did increase the volume of the central compartment (5.96 +/- 1.01 L for controls, 7.87 +/- 1.33 L for patients with liver disease) and volume of distribution at steady state (16.4 L for controls, 23.4 L for patients with liver disease). In turn, elimination half-life was longer in patients with liver disease (111 min) compared to controls (75.4 min). The authors conclude that liver disease alters the pharmacokinetics of rocuronium by increasing its volume of distribution. The longer elimination half-life might result in a longer duration of action of rocuronium in patients with liver disease, particularly after prolonged administration.

Stereochemical determinants of the nature and consequences of drug metabolism

Enantiomeric discrimination in drug disposition depends on the mechanism of the process under consideration. Absorption, distribution and excretion are generally passive processes which do not differentiate between enantiomers, but enzymic metabolism and protein binding, to plasma or tissue proteins, can show a high degree of stereoselectivity. In terms of metabolism, chiral discrimination occurs at both substrate and product levels, giving rise to five distinct stereochemical courses for drug metabolism, namely (i) prochiral-->chiral, (ii) chiral-->chiral, (iii) chiral-->diastereoisomer, (iv) chiral-->non-chiral and (v) chiral inversion. As a result, the metabolic and pharmacokinetic profiles of enantiomers after administration of racemic drugs can be very variable, so that the exposure to the two enantiomers may be very different. There now an enormous number of examples of each of these possibilities. The net result of the interaction of the stereoselectivities of these various processes can obscure the fact that one (or more) shows a marked stereoselectivity. This is particularly the case for metabolism: while the ratios of the total plasma clearance of the enantiomers of a wide range of drugs never exceed 2, individual metabolic pathways often show much greater stereoselectivity. This is particularly evident for those high-affinity, low-capacity enzyme systems which exhibit genetic polymorphism, namely the human cytochromes P450 2C18 and 2D6. This review provides an introduction to the stereoselectivity of drug metabolism.

An introduction to drug disposition: the basic principles of absorption, distribution, metabolism, and excretion

A knowledge of the fate of a drug, its disposition (absorption, distribution, metabolism, and excretion, known by the acronym ADME) and pharmacokinetics (the mathematical description of the rates of these processes and of concentration-time relationships), plays a central role throughout pharmaceutical research and development. These studies aid in the discovery and selection of new chemical entities, support safety assessment, and are critical in defining conditions for safe and effective use in patients. ADME studies provide the only basis for critical judgments from situations where the behavior of the drug is understood to those where it is unknown: this is most important in bridging from animal studies to the human situation. This presentation is intended to provide an introductory overview of the life cycle of a drug in the animal body and indicates the significance of such information for a full understanding of mechanisms of action and toxicity.

Stereochemical aspects of the hydration of trans-anethole epoxide in the rat

Racemic trans-anethole epoxide [1-(4'-methoxyphenyl)-propane-1,2-oxide] was incubated with water, buffers, and rat liver microsomes and cytosol and the stereochemistry of the diols produced was determined by HPLC as their dicamphanyl esters. The diol metabolites were isolated by HPLC from the urine of rats administered [1'-14C] trans-anethole and their stereochemistry determined after derivatization to their camphanyl esters. The stereochemical course of the metabolism of trans-anethole by rat liver microsomes and cytosol is discussed.

Metabolism of [propyl-3H]-8-hydroxy-2-(N,N-di-n-propylamino)tetralin in rat

1. Male Sprague-Dawley rats given (RS)-[3H]-8-OHDPAT by intraperitoneal (i.p.) or intravenous (i.v.) injection, or orally (p.o.) by gavage, excreted the majority of the dose in the urine (> 80% in 3 days and > 70% in the first 24 h). A smaller proportion of the dose was excreted in the faeces (> 10% in 3 days), mostly in the first 24 h. Total recovery was > 90% (mean: i.p. = 94.9; i.v. = 99 and p.o. = 92.9%). 2. Urinary metabolites were separated by reversed-phase hplc before and after treatment with beta-glucuronidase or sulphatase and quantitated by liquid scintillation spectrometry. Metabolites were identified by hydrolysis by specific enzymes, comparison of hplc retention time with those of authentic standards and by LC-MS. 3. Two major metabolites were identified and quantitated in the 24-h urine, namely 8-OHDPAT-glucuronide, accounting for some 45% of dose, and its N-despropylated metabolite, 8-hydroxy-2-(N-n-propylamino)tetralin, excreted as its glucuronide, which accounted for 15% of dose. Small amounts (< 1%) of two monohydroxylated metabolites were also identified, one eluting slightly earlier than and the other co-eluting with the mono-despropylated metabolite. When analysed by LC-MS-MS, the first of these exhibited a fragmentation pattern consistent with ring hydroxylation and the other appeared to be a side chain oxidized metabolite, which may constitute an intermediate in N-despropylation. However, these metabolites were present at too low a level to allow the exact position of hydroxylation to be determined. 4. These studies suggest that the low oral activity exhibited by 8-OHDPAT is most likely the result of rapid and extensive glucuronidation rather than poor absorption from the gastrointestinal tract.

Percutaneous absorption of benzyl acetate through rat skin in vitro. 3. A comparison with human skin

The comparative absorption of the fragrance and industrial compound, benzyl acetate, has been studied in rat and human skin, using shaved, full-thickness dorsal skin of male Fischer 344 rats and full-thickness human skin obtained from patients undergoing surgical resection. Penetration of the compound through rat and human skin was evaluated in vitro in flow-through diffusion cells following topical application of neat [methylene-14C] benzyl acetate (33.1 mg/cm2) to the epidermal surface and occlusion with a teflon cap, 2.9 cm above the skin surface. The absorption of benzyl acetate across rat skin was rapid and extensive, reaching 34.3 +/- 3.9% of the applied dose (11.3 +/- 1.3 mg/cm2) (mean +/- SD, n = 12) at 24 hr and 55.8 +/- 5.0% of the applied dose (18.5 +/- 1.7 mg/cm2) at 72 hr. The penetration of benzyl acetate was significantly (P < 0.05) less rapid and extensive through human skin, reaching 5.5 +/- 0.1% of the applied dose (1.8 +/- 0.0 mg/cm2) (mean +/- SD, n = 12) at 24 hr and 17.8 +/- 3.3% of the applied dose (5.9 +/- 1.1 mg/cm2) at 72 hr. The rate of penetration of benzyl acetate was greater through rat skin than through human tissue at all time points studied up to 72 hr. The maximum rate of skin penetration was 0.6 +/- 0.1 mg/cm2/hr and 0.1 +/- 0.0 mg/cm2/hr through rat and human skin, respectively. These data indicate that systemic exposure to benzyl acetate may occur after skin contact in humans. They also support the evidence from the literature that human skin is generally less permeable to xenobiotics than rat skin.

Metabolism and excretion of [14C]furfural in the rat and mouse

The fate of furfural (2-furancarboxaldehyde) was investigated in male and female Fischer 344 (F344) rats given single oral doses of 1, 10 and 60 mg/kg and male and female CD1 mice given 1, 20 and 200 mg/kg [carbonyl-14C]furfural. There was a very high recovery (more than 90% of dose) of radioactivity in all dose groups in 72 hr. The major route of elimination was by the urine, with much smaller amounts present in the faeces and exhaled as 14CO2. The residue in the carcass after 72 hr was less than 1% of the administered dose. Furoylglycine and furanacryloylglycine were identified as the major urinary metabolites by high-performance thin-layer chromatography, radio-HPLC, gas chromatography-mass spectrometry and 1H-nuclear magnetic resonance spectroscopy, by comparison with synthetic reference compounds. There were only subtle differences in the metabolic profile as a function of dose size, sex and species. An additional minor polar metabolite was excreted by male rats and mice, and the parent acids of the glycine conjugates were excreted at the higher doses. The results are discussed in terms of the participation of xenobiotics in the chain elongation reactions of fatty acid biosynthesis.

Metabolism of trans-cinnamic acid in the rat and the mouse and its variation with dose

The metabolism of [3-14C/phenyl-2H5] cinnamic acid was investigated in rats and mice at a dose level of 2.5 mmol/kg body weight. Recoveries of the 14C dose were between 92 and 98% with most (82-90%) present in the 0-24 hr urine samples. Urinary metabolites were identified by their chromatographic properties and mass spectra. In both species the major metabolite was hippuric acid, which is also an endogenous urinary component. Several minor metabolites, 3-hydroxy-3-phenylpropionic acid, benzoic acid and benzoyl glucuronide, were found in both species. Two, acetophenone and cinnamoylglycine, the glycine conjugate of cinnamic acid, could be positively identified only in mouse urine. The effect of dose size on the urinary excretion of 14C-cinnamic acid metabolites was studied over the dose range 0.0005 to 2.5 mmol/kg. In the rat the pattern of metabolite excretion was very similar over the whole dose range with slight increases in the proportion of the dose excreted as minor metabolites as dose size increased. In the mouse the excretion of cinnamoylglycine was more important at the lowest dose level and decreased in relative importance as dose size increased. Changes in the other metabolites were similar to those seen in the rat.

Studies on trans-cinnamaldehyde. 1. The influence of dose size and sex on its disposition in the rat and mouse

The metabolism of trans-[3-14C]cinnamaldehyde was investigated in male and female Fischer 344 rats and CD1 mice at doses of 2 and 250 mg/kg body weight given by ip injection and in males at 250 mg/kg by oral gavage. Some 94% of the administered dose was recovered in the excreta in 72 hr in both species with most (75-81%) present in the 0-24-hr urine. Less than 2% of the administered dose was found in the carcasses at 72 hr after dosing. Urinary metabolites were identified by their chromatographic characteristics. In both species the major urinary metabolite was hippuric acid accompanied by 3-hydroxy-3-phenylpropionic acid, benzoic acid and benzoyl glucuronide. The glycine conjugate of cinnamic acid was formed to a considerable extent only in the mouse. The oxidative metabolism of cinnamaldehyde essentially follows that of cinnamic acid, by beta-oxidation analogous to that of fatty acids. Apart from the metabolites common to cinnamic acid and cinnamaldehyde, 7% of 0-24-hr urinary 14C was accounted for by two new metabolites in the rat and three in the mouse, which have been shown in other work to arise from a second pathway of cinnamaldehyde metabolism involving conjugation with glutathione. The excretion pattern and metabolic profile of cinnamaldehyde in rats and mice are not systematically affected by sex, dose size and route of administration. The data are discussed in terms of their relevance to the safety evaluation of trans-cinnamaldehyde, particularly the validity or otherwise of extrapolation of toxicity data from high to low dose.

Spatial Organization and Time Dependence of Jupiter's Tropospheric Temperatures, 1980-1993

The spatial organization and time dependence of Jupiter's temperatures near 250-millibar pressure were measured through a jovian year by imaging thermal emission at 18 micrometers. The temperature field is influenced by seasonal radiative forcing, and its banded organization is closely correlated with the visible cloud field. Evidence was found for a quasi-periodic oscillation of temperatures in the Equatorial Zone, a correlation between tropospheric and stratospheric waves in the North Equatorial Belt, and slowly moving thermal features in the North and South Equatorial Belts. There appears to be no common relation between temporal changes of temperature and changes in the visual albedo of the various axisymmetric bands.

Metabolic fate of [3H]-l-menthol in the rat

[3-3H]-l-Menthol was administered by oral gavage to intact and bile duct-cannulated male Fischer 344 rats at a dose level of 500 mg/kg. Excreta were collected for up to 48 hr and metabolites in urine and bile analyzed by TLC, solid phase extraction, GLC, and GC/MS. In intact rats, some 71% of the dose was recovered in 48 hr with approximately equal amounts in urine and feces. Seventy-four percent of the dose was recovered from bile duct-cannulated rats, with 67% in the bile and 7% in the urine. The major biliary metabolite was menthol glucuronide, which undergoes enterohepatic circulation. The urinary metabolites resulted from hydroxylation at the C-7 methyl group at C-8 and C-9 in the isopropyl moiety, resulting in a series of mono- and dihydroxy-menthols and carboxylic acids, some of which are excreted in part as glucuronic acid conjugates. In addition, menthol glucuronide is found in the urine. The results have enabled the construction of a metabolic map for menthol in the rat that provides the basis for structure-metabolism relationships describing the fate of numerous menthol congeners of flavor importance.

IL-1 alpha and TNF alpha act synergistically to stimulate production of myeloid colony-stimulating factors by cultured human bone marrow stromal cells and cloned stromal cell strains

Human bone marrow stromal cells respond to stimulation by the monokines IL-1 and TNF by producing colony-stimulating factors such as GM-CSF and G-CSF. In this study we show that IL-1 alpha and TNF alpha act synergistically to stimulate GM-CSF and G-CSF production by cultured marrow stromal cells. We further show that IL-1 alpha and TNF alpha synergistically stimulate production of GM-CSF and G-CSF by a clonal stroma-derived cell strain. Although IL-1 and TNF share many of the same biological activities, we show that IL-1 alpha and TNF alpha have an unequal ability to induce myeloid-CSF production by both cultures, with IL-1 alpha being the more potent inducer. We found that induction by IL-1 alpha and TNF alpha was independent of cell proliferation. The effect of IL-1 alpha and TNF alpha on production of the two myeloid-CSFs by the clonal cells was significantly greater than the unfractionated passaged stromal cultures, having the greater effect on G-CSF production. The clonally derived stromal cells constitutively produced colony-stimulating activity, in particular GM-CSF, at levels easily detected by ELISA. These findings show that, in addition to the overlapping and additive activities of IL-1 alpha and TNF alpha, they can interact synergistically. Our findings further suggest that a small subpopulation of stroma cells may be the major producer of G-CSF in the marrow microenvironment during immune response.

Genotoxicity of the alkenylbenzenes alpha- and beta-asarone, myristicin and elimicin as determined by the UDS assay in cultured rat hepatocytes

While the alkenylbenzenes alpha- and beta-asarone are hepatocarcinogenic in rodents, myristicin and elimicin, two other alkenylbenzenes, are not. The present study investigated the mechanism of genotoxicity of the asarones to elucidate the role of cytochrome P-450 and obtain further information about the relationships between the structure, metabolism and genotoxicity of the alkenylbenzenes. The data on the ability of these compounds to induce unscheduled DNA synthesis (UDS) in hepatocytes derived from male Fischer 344 rats are presented in this paper. Cytotoxicity was assessed by lactate dehydrogenase leakage. Elimicin and alpha- and beta-asarone are genotoxic in the UDS assay but myristicin is not. The genotoxicity of the asarones is inhibited by the cytochrome P-450 inhibitor cimetidine but the sulfotransferase inhibitor pentachlorophenol (PCP) is without effect. The major metabolite of the asarones in hepatocytes was identified by liquid chromatography-mass spectrometry as 2,4,5-trimethoxycinnamic acid but this was not genotoxic when tested separately. Simple allylbenzenes such as safrole, estragole and methyleugenol are activated by sequential 1-hydroxylation and sulfation, and this is the likely mechanism of the genotoxicity of elimicin. The propenyl analogues isosafrole, anethole and methylisoeugenol, which cannot undergo 1-hydroxylation, are not genotoxic. The positive results obtained with the asarones suggest the occurrence of a novel activation 'option' for alkenylbenzenes which features a 2-methoxy group in the aromatic ring.

Effective hospice volunteers: demographic and personality characteristics

The purpose of the study was to examine demographic and personality characteristics of highly effective hospice volunteers. Volunteer coordinators of all Texas Hospice Organization member hospices were asked to select their most committed and effective volunteers to participate in the study. Volunteers had above-average incomes, were predominately white, female, active in other voluntary activities, and motivated by their own experiences with death of a loved one. The largest proportion of female volunteers (27.3 percent) were extroverted, sensing, feeling, judging personality types (ESFJ), whereas, for male volunteers, the largest proportion (20.8 percent) were introverted, sensing, thinking, judging personality types (ISTJ). This information will be beneficial in recruitment, training, and retention of hospice volunteers.

Cloning of an intracellular receptor for protein kinase C: a homolog of the beta subunit of G proteins

Protein kinase C (PKC) translocates from the soluble to the cell particulate fraction on activation. Intracellular receptors that bind activated PKC in the particulate fraction have been implicated by a number of studies. Previous work identified 30- to 36-kDa proteins in the particulate fraction of heart and brain that bound activated PKC in a specific and saturable manner. These proteins were termed receptors for activated C-kinase, or RACKs. In the following study, we describe the cloning of a cDNA encoding a 36-kDa protein (RACK1) that fulfills the criteria for RACKs. (i) RACK1 bound PKC in the presence of PKC activators, but not in their absence. (ii) PKC binding to the recombinant RACK1 was not inhibited by a pseudosubstrate peptide or by a substrate peptide derived from the pseudosubstrate sequence, indicating that the binding did not reflect simply PKC association with its substrate. (iii) Binding of PKC to RACK1 was saturable and specific; two other protein kinases did not bind to RACK1. (iv) RACK1 contains two short sequences homologous to a PKC binding sequence previously identified in annexin I and in the brain PKC inhibitor KCIP. Peptides derived from these sequences inhibited PKC binding to RACK1. Finally, RACK1 is a homolog of the beta subunit of G proteins, which were recently implicated in membrane anchorage of the beta-adrenergic receptor kinase [Pitcher, J., Inglese, L., Higgins, J. B., Arriza, J. A., Casey, P. J., Kim, C., Benovic, J. L., Kwatra, M. M., Caron, M. G. & Lefkowitz, R. J. (1992) Science 257, 1264-1267]. Our in vitro data suggest a role for RACK1 in PKC-mediated signaling.

Computerized screening for appropriate dosing of renally eliminated medications

A method of rapid screening for appropriateness of certain drug doses is described. The program extracts patient information from a hospital mainframe computer system, performs an estimation of creatinine clearance (CrCl), and prints a report of patients, drugs, doses, and CrCl for patients within a specified CrCl range.

Structure-genotoxicity relationships of allylbenzenes and propenylbenzenes: a quantum chemical study

Quantum mechanical calculations at the semiempirical level (AM1 method) were conducted for estragole (1), methyleugenol (2), safrole (3), alpha-asarone (4), beta-asarone (5), elemicin (6), allylbenzene (7), eugenol (8), trans-anethole (9), isosafrole (10), and myristicin (11), and the results compared with the known genotoxicity of 1-6 and the absence of genotoxicity of 7-11 (unscheduled DNA synthesis assay). The various compounds showed no significant differences in the relative stability of the radical species formed as intermediates in C-sp3 hydroxylation (delta HR(radical)) and in the corresponding enthalpy of activation (delta H++). In contrast, the carbonium ions of the genotoxic congeners 1-6 were shown to be comparatively more stable than those of the inactive compounds 7-11, with the exception of eugenol (8). The inactivity of this compound could be due to a very rapid stabilization of the carbonium ion by deprotonation to form a quinone methide, as suggested by quantum chemical calculations. The relative stability of the carbonium ion thus appears to be one of the key factors in the genotoxicity of allylbenzenes and propenylbenzenes.

Lack of stereoselectivity of the peroxisome proliferation induced by 2-phenylpropionic acid: evidence against a role for lipid disturbance in peroxisome proliferation

The significance of disturbances of lipid metabolism caused by xenobiotic acyl-CoAs as possible causes of peroxisomal proliferation has been studied with the enantiomers of 2-phenylpropionic acid (2-PPA), the (R)-enantiomer of which is converted to the acyl-CoA in rats while its (S)-antipode is not. rac-2-PPA (250 mg/kg/day ip x 3) was shown to be an hepatic peroxisomal proliferator in male Sprague-Dawley rats on the basis of increases in microsomal cytochrome P-450 content and lauric acid hydroxylation and hepatic CN(-)-insensitive palmitoyl-CoA oxidation, a peroxisomal marker activity, while electron microscopy revealed a rise in the peroxisome/mitochondria ratio in hepatocytes. Further studies established the dose-response relationships for these biochemical changes. The (R)- and (S)-enantiomers were administered at a dose of 50 mg/kg/day ip x 3 and both were peroxisome proliferators of very similar potency. The effects of 100 mg/kg/day ip x 3 of the racemate, a dose giving ca. 75% of maximal response, were essentially additive of those of 50 mg/kg/day ip x 3 of its two component isomers. The stereoselectivity of acyl-CoA formation from the enantiomers of 2-PPA was confirmed by their differential inhibition of microsomal palmitoyl-CoA synthesis. Taken together, these data indicate that it is very unlikely that the acyl-CoA of 2-PPA plays any role in the peroxisomal proliferation which this compound causes in the rat.