Trainee experience in diagnosis and management of personality disorders.

The diagnosis and management of personality disorders continues to evolve and develop alongside psychiatry internationally, however, not always in a linear fashion. Trainees working in a variety of clinical areas have regular exposure to personality disorder presentations. Psychiatry training bodies continue to adapt their training structure and curriculum, however, there seems to be a lack of sufficient emphasis with regards this area. We are now embarking on a new diagnostic system for personality disorders; this may impact on our clinical practice and perspective of these patients. The role of psychiatrists in diagnosing and managing personality disorders can be unclear at times and may benefit from on-going reflection and standardization.

Client personal recovery and recovery orientation of an Irish suicide intervention charity.

BACKGROUND: Recovery is a key goal for individuals, and services' recovery orientation can facilitate this process. The independent mental health sector is increasingly important in Ireland, particularly in counselling and suicide prevention. We aimed to evaluate Pieta House as a recovery-oriented service through clients' self-rated recovery; and clients' and therapists' evaluation of the service. METHODS: Clients completing therapy over a 3-month period were invited to complete the Recovery Assessment Scale (RAS) and the Recovery Self Assessment-Revised (RSA-R). Therapists completed the RSA-R staff version. RESULTS: Response rate was 36.7% for clients (n=88), 98% for therapists (n=49). Personal recovery was endorsed by 73.8% of clients, with highest agreement for factors 'Willingness to Ask for Help' (84.5%), and 'Reliance on Others' (82.1%). A smaller number agreed with factors 'Personal Confidence and Hope' (61.3%) and 'No Domination by Symptoms' (66.6%). Clients' and therapists' evaluation of the service showed high levels of agreement with factors of 'Choice' (90.9% clients, 100% therapists); 'Life Goals' (84.1% clients, 98% therapists) and 'Individually Tailored Services' (80.6% clients, 79.6% therapists). Client involvement in service management had the lowest level of agreement (36.4% clients, 30.6% therapists). Clients' self-rated recovery correlated with their rating of the service (correlation value 0.993, p=0.01). CONCLUSIONS: Clients' self-rated recovery and the recovery orientation of Pieta House were rated highly, with areas for improvement in service user involvement, peer support and advocacy. The correlation of personal recovery and recovery orientation of the service may merit further study.

Modified Drop Tower Impact Tests for American Football Helmets.

A modified National Operating Committee on Standards for Athletic Equipment (NOCSAE) test method for American football helmet drop impact test standards is presented that would provide better assessment of a helmet's on-field impact performance by including a faceguard on the helmet. In this study, a merger of faceguard and helmet test standards is proposed. The need for a more robust systematic approach to football helmet testing procedures is emphasized by comparing representative results of the Head Injury Criterion (HIC), Severity Index (SI), and peak acceleration values for different helmets at different helmet locations under modified NOCSAE standard drop tower tests. Essentially, these comparative drop test results revealed that the faceguard adds a stiffening kinematic constraint to the shell that lessens total energy absorption. The current NOCSAE standard test methods can be improved to represent on-field helmet hits by attaching the faceguards to helmets and by including two new helmet impact locations (Front Top and Front Top Boss). The reported football helmet test method gives a more accurate representation of a helmet's performance and its ability to mitigate on-field impacts while promoting safer football helmets.

Feasibility study on the MammoSite in early-stage breast cancer: initial experience.

The aims of this study were to evaluate the feasibility, practicality, efficacy and safety of the delivery of accelerated partial breast irradiation using the MammoSite for the boost phase. Six patients aged 53-69 years with stage T1N0, T2N0, Grade I-II invasive ductal carcinoma received 9-10 Gy prescribed at 1 cm from the MammoSite balloon surface in two fractions of 4.5-5 Gy 6 h apart. The MammoSite was inserted 20-37 days postoperatively. External beam radiation therapy to the whole breast commenced 1-5 days after accelerated partial breast irradiation. The maximum skin dose ranged from 3 to 9 Gy. The skin-cavity distance ranged from 7 to 19 mm. Local discomfort resolved as the scar healed spontaneously within 3-5 days. No Grade III or higher acute toxicity or local infection was recorded. The ease of insertion and accuracy of dosimetry makes the MammoSite suitable for use in properly selected women with early-stage breast cancer in a trial setting.

Total mercury and methylmercury levels in some New Zealand commercial marine fish species.

Two groups of samples spanning 16 years are reported for methylmercury and total mercury. All the samples had been taken from commercial catches and represent 33 different commercially important New Zealand marine fish species. Results show the New Zealand fish species sampled have mean contents of total mercury that range between 0.02 and 2.48 mg kg(-1) and mean contents of methylmercury that range from less than 0.04 to 1.97 mg kg(-1).

Monitoring working memory load during computer-based tasks with EEG pattern recognition methods.

We assessed working memory load during computer use with neural network pattern recognition applied to EEG spectral features. Eight participants performed high-, moderate-, and low-load working memory tasks. Frontal theta EEG activity increased and alpha activity decreased with increasing load. These changes probably reflect task difficulty-related increases in mental effort and the proportion of cortical resources allocated to task performance. In network analyses, test data segments from high and low load levels were discriminated with better than 95% accuracy. More than 80% of test data segments associated with a moderate load could be discriminated from high- or low-load data segments. Statistically significant classification was also achieved when applying networks trained with data from one day to data from another day, when applying networks trained with data from one task to data from another task, and when applying networks trained with data from a group of participants to data from new participants. These results support the feasibility of using EEG-based methods for monitoring cognitive load during human-computer interaction.

Evaluation of the genotoxicity potential and chronic inhalation toxicity of 1,1-dichloro-1-fluoroethane (HCFC-141b).

A battery of in vitro and in vivo tests were conducted on HCFC-141b as a vapour. Bacterial gene mutation assays with Escherichia coli and Salmonella typhimurium were negative in all tester strains. In vitro chromosomal aberration assays were positive on CHO cells but negative on human lymphocytes. Moreover, HCFC-141b was negative in vivo in a mouse micronucleus inhalation assay. On the basis of these data and previously reported genotoxicity testing, HCFC-141b is considered non-genotoxic. Groups of 80 male and 80 female Sprague-Dawley rats were exposed, by inhalation (6 hr/day, 5 days/wk) to vapours of HCFC-141b for 104 wk at target concentrations of 0 (control), 1500, 5000 and 20,000 ppm (increased from 15,000 ppm after 17 wk of exposure). No exposure-related effects of toxicological significance were noted with respect to survival, clinical signs, ophthalmoscopy, haematology, clinical chemistry, urinalysis or organ weight analysis. Reduced food intake and body weight gain were noted in both sexes of the 15,000 ppm group during the first 16 wk; thereafter, body weight gains in all groups were similar although the intergroup differences in body weight remained evident. Reduced food intake persisted in both sexes through wk 52 and in females during the second year of exposure. Treatment-related effects on macroscopic pathology were confined to increased incidences of testicular masses and altered appearance. Microscopic pathology examinations confirmed the testes as the target organ with findings of increased incidences of benign interstitial cell tumours and hyperplasia at 5000 and 20,000 ppm. The no-observable-adverse-effect level (NOAEL) was 1500 ppm. The testicular changes at high exposure levels were considered to be due to a change of the senile hormonal imbalance in geriatric rats and of little significance for the assessment of human health effects.

General pharmacology of gemcitabine hydrochloride in animals.

Gemcitabine (2',2'-difluorodeoxycytidine monohydrochloride, LY188011 hydrochloride, CAS 122111-03-9) is a nucleoside analog with a broad spectrum of antitumor activity in murine models and is currently undergoing clinical evaluation. The profile of the pharmacological effects of this agent was assessed in studies evaluating the cardiovascular and respiratory systems, renal function, the gastrointestinal system, the central nervous system, and the autonomic nervous system. In vivo doses ranged from 0.15 to 300 mg/kg given by the intravenous route, while in vitro concentrations up to 1 x 10-3 mol/l were used. Gemcitabine was inactive in the autonomic nervous system, gastrointestinal function, and central nervous system studies. Only minimal changes were seen in the cardiovascular and respiratory study, with a slight decrease in pulmonary arterial pressure at the mid dose and a stroke volume increase at the high dose. In the renal function studies, a slight decrease in the urine pH at the high dose and decreased serum creatinine at the mid dose levels were observed. In summary, gemcitabine had minimal effect in these pharmacodynamic studies. These results indicate that gemcitabine has a low potential to produce adverse pharmacologic effects.

Effects of diarylsulfonylurea antitumor agents on the function of mitochondria isolated from rat liver and GC3/c1 cells.

Diarylsulfonylureas, such as N-(4-chlorophenyl)aminocarbonyl-2,3-dihydro-1-indene-5-sulfonamide (LY186641, Sulofenur) and N-(4-chlorophenyl)aminocarbonyl-4-methylbenzene sulfonamide (LY181984), have been shown to be effective antitumor agents in a variety of in vivo and in vitro animal models. Their mechanism of action is unknown but does not appear to be the result of nonselective destruction of actively dividing cell populations. Mitochondria have been shown to accumulate Sulofenur and therefore may be targets of drug action. The purpose of these investigations was to examine the effects of a variety of diarylsulfonylureas in mitochondria and attempt to determine the relevance of these changes to antitumor activity. Many of the diarylsulfonylureas which were effective antitumor agents in animal models were also uncouplers of mitochondrial oxidative phosphorylation. They increased state 4 respiration and dissipated the mitochondrial membrane potential in a concentration-related fashion. The mechanism of uncoupling appeared to be related to a dissociable hydrogen ion as these molecules had pKa values that ranged from 6.0 to 6.2 and were highly lipophilic. Thus, the uncoupling action appears to be the result of hydrogen ion translocation. The mechanism of antitumor activity does not appear to be the result of uncoupling as no correlation was evident between inhibition of cell growth and uncoupling action of a variety of active and inactive diarylsulfonylureas. In vitro, Sulofenur is cytotoxic at high concentrations and inhibits cell growth at lower concentrations in the absence of any overt cell kill. The inhibition of cell growth also did not appear to be related to the uncoupling action of these drugs. In contrast, uncoupling may have played a partial role in the early, high exposure cell kill that can occur with these compounds.

Effects of methapyrilene measured in mitochondria isolated from naive and methapyrilene-treated rat and mouse hepatocytes.

Methapyrilene (MP) is a rat-specific liver carcinogen that alters mitochondrial number and morphology both in vivo and in vitro. This biological phenomenon may be due to the effects of MP on mitochondrial function. To test this hypothesis, studies were conducted to examine the effects of MP on DNA and protein synthesis and respiration in isolated mitochondria. DNA and protein synthesis activities were measured using [3H]thymidine and [3H]leucine incorporation. Mouse liver mitochondria were also examined for comparison since no tumor formation or alterations in mitochondrial morphology have been associated with MP treatment in mice. A significant decrease in basal DNA and protein synthesis levels was observed in mitochondria isolated from rats and mice following in vivo MP treatment. This effect could not be reproduced when mitochondria were exposed to 0 or 100 microM MP following isolation, despite the presence of an S9 activation system. Electron microscopic examinations were performed on isolated rat mitochondria and revealed morphologic differences between mitochondria from naive and MP-treated rats. Although significant differences in State 3 and State 4 respiratory rates were noted, the respiratory control ratio, ADP/O ratio, and uncoupler-stimulated respiratory rates were unaffected. Results demonstrate that: (1) MP irreversibly depresses DNA and protein synthesis in a majority of mitochondria, despite only localized morphologic changes; (2) these changes are not reflected by a decrease in respiratory function; and (3) depression of DNA and protein synthesis does not correlate with carcinogenic susceptibility.

Cephaloridine-induced renal pathological and biochemical changes in female rabbits and isolated proximal tubules in suspension.

Cephaloridine (Cld) is a nephrotoxic cephalosporin antibiotic. The intracellular biochemical changes that occur leading to Cld-induced nephrotoxicity may involve lipid peroxidation and/or mitochondrial injury. The purpose of this report was to examine and correlate the biochemical changes induced by Cld in vivo and in vitro with the observed pathological changes in an attempt to understand better the mechanisms of beta-lactam-induced nephrotoxicity. Cld treatment (500 mg/kg sc) caused elevations in blood urea nitrogen and decreases in the accumulation of p-aminohippurate (PAH) and tetraethylammonium (TEA) by renal cortical slices. Histopathological alterations, characterized by individual cell necrosis of tubular epithelial cells, were first seen 6 hr after treatment in the pars recta of the outer stripe of the medulla. Ultrastructural alterations involved the straight (S2 and S3) segments of the proximal tubules. Mitochondrial morphology was, for the most part, unaffected by Cld exposure. Cld did not cause any significant changes in tissue malondialdehyde (MDA) content in vivo at any of the time points examined, but it did cause a depletion of GSH to approximately 40% of control by 1 hr after dosing that recovered toward control by 6 hr. Significant changes were observed in renal ATP content beginning at 6 hr after treatment; however, this change mirrored the onset of histological evidence of necrosis. In isolated tubules in vitro, the onset of glutathione (GSH) depletion and MDA formation clearly preceded lactate dehydrogenase (LDH) leakage, whereas ATP depletion was a mirror image of cell death. These data demonstrate that isolated proximal tubules in vitro are a reasonable model for Cld nephrotoxicity in vivo. Cld-induced mitochondrial alterations leading to ATP depletion and cell injury were not observed in this study.

Cephaloridine-induced biochemical changes and cytotoxicity in suspensions of rabbit isolated proximal tubules.

Cephalosporin antibiotics, such as cephaloridine (Cld), are known to be nephrotoxic in vivo and in vitro. In vivo, Cld causes proximal tubule necrosis in rabbits which is preceded by glutathione (GSH) depletion and, under certain conditions, inhibition of mitochondrial function. In vitro, Cld causes GSH depletion, lipid peroxidation, and inhibition of rat kidney slice organic ion uptake. The present investigations were designed to evaluate the temporal relationships of the biochemical "lesions" caused by Cld to the onset of lethal cell injury in suspensions of isolated rabbit proximal tubules. Cld was cytotoxic to suspensions of rabbit proximal tubules (EC50 = 1.10 +/- 0.33 mM) in the absence of amino acids (to support GSH synthesis). In this model, Cld also caused GSH and ATP depletion, lipid peroxidation (malondialdehyde formation), and inhibition of tubule respiration. Probenecid prevented Cld accumulation, tubule injury, ATP depletion, and lipid peroxidation and markedly attenuated the GSH depletion. Addition of glycine, cystine, and glutamate to the incubation buffer to support GSH synthesis decreased the tubule accumulation of Cld (due solely to the presence of glutamate) and blocked Cld-induced tubule lethality, lipid peroxidation, ATP depletion, and GSH depletion. Glycine or glutamate alone had no effect on Cld-induced cytotoxicity, whereas cystine was cytoprotective. Buthionine sulfoximine partially reversed the amino acid protection against Cld-induced tubule injury. Thus amino acid-induced protection of tubules from Cld cytotoxicity was due to the combination of a high intracellular GSH content and cytoprotection by cystine. The antioxidant N-N'-diphenyl-p-phenylenediamine (DPPD) blocked tubule injury, ATP depletion, and lipid peroxidation but had no effect on Cld-induced GSH depletion when tubules were incubated for 3 hr. However, when incubations were allowed to run for up to 8 hr, DPPD had no effect on Cld cytotoxicity, despite continued inhibition of lipid peroxidation. These data demonstrate that Cld-induced tubule injury in short-term (3 hr) incubations in vitro occurs by a mechanism probably involving lipid peroxidation and occurs only in the absence of amino acids to support GSH synthesis. Inhibition of tubule respiration and ATP depletion could not clearly be causally linked to the onset of cell death in this model. The mechanism of the peroxidation-independent Cld toxicity in tubules incubated for 8 hr or longer is not known at this time.

The effects of fructose on adenosine triphosphate depletion following mitochondrial dysfunction and lethal cell injury in isolated rat hepatocytes.

Mitochondrial injury in aerobic mammalian cells is associated with a rapid depletion of adenosine triphosphate (ATP) which occurs prior to the onset of lethal cell injury. In this report, the relationships between ATP depletion and lethal cell injury were examined in rat hepatocytes using oligomycin as a model mitochondrial toxicant and fructose as an alternative carbohydrate source for glycolysis. Oligomycin was more potent in causing lethal cell injury in hepatocytes isolated from fasted animals than cells from fed animals. The onset of cell injury (leakage of lactate dehydrogenase) in cells from fed animals correlated with the depletion of stored glycogen and ATP. The degree and time course profile of oligomycin-induced ATP depletion could be duplicated with 50 mM fructose alone in hepatocytes from fasted animals; however, fructose did not cause lethal cell injury. Oligomycin caused marked accumulation of adenosine monophosphate (AMP) and inorganic phosphate (Pi) and a conservation of adenine nucleotides. In contrast, fructose (50 mM) caused a decrease in Pi, no persistent change in AMP, and a depletion of the adenine nucleotide pool. Fructose, at concentrations greater than 1.0 mM, protected hepatocytes from oligomycin-induced toxicity. Blockade of mitochondrial ATP synthesis with oligomycin resulted in massive ATP depletion. In the presence of oligomycin, 5.0 mM fructose maintained cellular ATP content similar to that of control cells, whereas 50 mM fructose did not, demonstrating the biphasic effect of increasing fructose concentrations on cellular ATP content. Fructose-induced protection of hepatocytes from oligomycin toxicity was due to glycolytic fructose metabolism as hepatocytes incubated with iodoacetate (30 microM), fructose, and oligomycin had reduced viability and ATP content. In conclusion, interruption of mitochondrial ATP synthesis leads to marked ATP depletion and lethal cell injury. Cell injury is clearly not due to ATP depletion alone since increased glycolytic ATP production from either glycogen or fructose can maintain cell integrity in the absence of mitochondrial ATP synthesis and at low cellular ATP levels.

In vivo development and in vitro characterization of a subclone of murine P388 leukemia resistant to bis(diphenylphosphine)ethane.

Bis(diphenylphosphine)ethane (DPPE) and its gold coordination complexes have demonstrated antitumor activity in transplantable tumor models. This report describes the development of a P388 cell line (P388/DPPEc) that is resistant to DPPE and its analogues and the in vitro characterization of the cross-resistance of this subline to various antitumor and cytotoxic agents. The P388/DPPE tumor cell line was developed by serial transplantation in DPPE-treated mice. Resistance to DPPE was phenotypically stable. The P388/DPPE subline was cross-resistant to DPPE analogues and metal coordination complexes of DPPE. In addition, P388/DPPE cells were resistant to several mitochondrial uncouplers, including rhodamine-123, tetraphenylphosphonium, and carbonylcyanide-p-trifluro-methoxyphenyl hydrazone. P388/DPPE cells were less capable of sequestering and retaining 123Rh than were sensitive (P388/S) cells. Exposure to Au(DPPE)2+, a gold complex of DPPE with increased antitumor activity, resulted in a depletion of cellular ATP; the depletion was more rapid in the sensitive than the resistant cells. The rate of mitochondrial respiration, as measured by 14CO2 evolution from [6-14C]glucose, was greater in P388/S than in P388/DPPE. As with that evidenced for 123Rh, the cellular uptake of radiolabeled DPPE was decreased in P388/DPPEc cells. The results suggest that the basis for the resistance of this cell line may be an alteration in mitochondrial membrane potential. These data and the striking cross-resistance of P388/DPPE to mitochondrial uncouplers support the hypothesis that mitochondria may be one target involved in the cytotoxic or antitumor activities of these compounds. Mitochondria may also be causally related to the cytotoxic or antitumor activities, in that DPPE may be concentrated in cells via the presence of the inner mitochondrial membrane potential. Thus, P388/DPPE cells can serve as a tool to screen for and evaluate drugs that rely on affecting mitochondrial function, either mechanistically or causally, for their antitumor efficacy.

Internalization of recombinant tissue-type plasminogen activator by isolated rat hepatocytes is via coated pits.

The uptake and internalization of tissue-type plasminogen activator (t-PA) by freshly isolated rat hepatocytes was investigated. Electron microscopic examination of the uptake of t-PA-colloidal gold conjugates (t-PA-gold) by isolated rat hepatocytes showed that t-PA-gold was internalized via coated pits. This was inhibited with excess t-PA. Uptake of 125I-t-PA by isolated rat hepatocytes was a rapid, saturable, and specific process. The initial rate of specific uptake was 0.1 fmol/10(6) cells per min. The specific uptake plateaued at 1.4 fmol/10(6) cells by 30 min and declined to 0.8 fmol/10(6) cells at 2 h. Depletion of cellular ATP by 85-90% did not affect the initial rate of specific uptake. However, specific uptake by ATP-depleted hepatocytes at 30 min was reduced by 37%. By 2 h specific uptake by ATP-depleted hepatocytes was only 5% lower than by untreated hepatocytes, suggesting that processing of t-PA and/or its receptor is ATP-dependent. Uptake of 125I-t-PA was temperature dependent. Specific uptake was reduced by approximately 20% at 22 degrees C and by 70% at temperatures below 16 degrees C. Finally, inhibition of coated pit formation by K(+)-depletion with nigericin decreased the uptake of 125I-t-PA. This inhibition was shown to be K(+)-specific since treatment with nigericin in the presence of K+ did not inhibit coated pit formation or 125I-t-PA uptake. A threshold K(+)-depletion level for inhibition of coated pit formation was also demonstrated since treatment under conditions that reduced cellular K+ by only 54% had no effect on coated pit formation or 125I-t-PA uptake. These data support our hypothesis that internalization of t-PA by isolated rat hepatocytes is via coated pits and suggest that uptake of t-PA is a receptor-mediated process.

Mechanism of inhibition of rat liver mitochondrial respiration by oxmetidine, an H2-receptor antagonist.

Suspensions of rat liver hepatocytes exposed to oxmetidine rapidly lose viability, an event preceded by a marked and rapid inhibition of cell respiration and depletion of ATP. In isolated rat liver mitochondria (RLM), oxmetidine inhibits pyruvate/malate- but not succinate-supported, ADP-stimulated oxygen consumption (state 3). The purpose of this investigation was to determine the exact molecular site of oxmetidine-induced inhibition of RLM electron transport. Oxmetidine did not significantly inhibit succinate-supported, ADP-stimulated state 3 oxygen consumption in isolated RLM at concentrations up to 0.5 mM. In contrast, oxmetidine significantly inhibited beta-hydroxybutyrate- or isocitrate-supported mitochondrial state 3 oxygen consumption at concentrations above 10 microM and 25 microM, respectively. In RLM electron transport particles (ETP), oxmetidine inhibited NADH-oxidase and NADH-CoQ reductase activity (IC50 of 3.4 microM and 2.6 microM, respectively). However, oxmetidine did not significantly affect NADH-Fe3(CN)6 reductase activity (at concentrations up to 200 microM). SK&F 92058, a thiourea analog of oxmetidine approximately 24-fold less toxic to hepatocytes, produced a similar pattern of inhibition of respiration, although far less potent (IC50 of 0.8 mM and 0.6 mM for NADH-oxidase and NADH-CoQ reductase, respectively). SK&F 92058 did not significantly inhibit NADH-Fe3(CN)6 reductase activity at concentrations up to 3.0 mM. Studies with [14C]oxmetidine failed to show any specific, saturable binding to rat liver ETP.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo and in vitro cardiotoxicity of a gold-containing antineoplastic drug candidate in the rabbit.

Bis[1,2-bis(diphenylphosphino)ethane] gold(I) chloride (Au(DPPE)+2), a cytotoxic antineoplastic drug candidate, was cardiotoxic in rabbits. Intravenous administration of Au(DPPE)+2 (15 mg/kg) as a single dose produced multiple, 2- to 5-mm subendocardial and myocardial lesions, macroscopically appearing as pale tan foci. Histologically, these lesions consisted of widely scattered zones of myocardial cell necrosis and mineralization. The myocardium also contained multifocal areas of contraction band necrosis in which aggregated clumps of disorganized myofilaments were contiguous with areas of sarcoplasm which were relatively devoid of myofilaments. In a series of in vitro studies, electron microscopic examination of isolated rabbit myocytes treated with 30 microM Au(DPPE)+2 for 15 min showed evidence of mitochondrial swelling and electron translucent mitochondrial matrices. After 60 min of incubation, myocytes had mitochondria that were condensed and disrupted but the cristae had retained their tubular profiles. Isolated rabbit myocytes exposed to 30 microM Au(DPPE)+2 had significant increases in the leakage of lactate dehydrogenase, an index of cell death. Cellular ATP content in myocytes exposed to 30 microM Au(DPPE)+2 was significantly reduced by 30 min. State 4 respiration in isolated rabbit mitochondria was significantly increased by Au(DPPE)+2 (30 microM) while state 3 respiration was unaffected. Au(DPPE)+2 also caused a rapid dissipation of the mitochondrial inner membrane electrochemical potential in a concentration-dependent manner and was accompanied by a ruthenium red-sensitive calcium efflux. These data suggest that disruption of mitochondrial function, leading to uncoupling of oxidative phosphorylation, decreased ATP synthesis, and altered mitochondrial calcium homeostasis, may be a contributing factor leading to cardiac myofibril necrosis produced by Au(DPPE)+2.

The mechanism of acute cytotoxicity of triethylphosphine gold(I) complexes. III. Chlorotriethylphosphine gold(I)-induced alterations in isolated rat liver mitochondrial function.

Chlorotriethylphosphine gold(I) (TEPAu) is an organo-gold compound that has therapeutic activity in animal models of rheumatoid arthritis. Initial studies have suggested that TEPAu is a potent cytotoxic compound in vitro against a variety of cultured cell types and isolated hepatocytes. Mitochondrial dysfunction induced by this compound has been suggested as a primary biochemical alteration which may result in lethal cell injury in isolated hepatocytes. The purpose of this study was, therefore, to determine the mechanism of TEPAu-induced dysfunction of isolated rat liver mitochondria. TEPAu induced a rapid, concentration-related collapse of the mitochondrial inner membrane potential (EC50 = 24.7 +/- 2.5 microM) which was potentiated in Ca2+ loaded mitochondria (EC50 = 11.3 +/- 3.8 microM). TEPAu-induced collapse of the membrane potential was partially inhibited in the presence of ruthenium red or EGTA. TEPAu caused the rapid release of mitochondrially sequestered Ca2+ which was not inhibited by ruthenium red and, thus, was not via a reversal of the Ca2+ uniporter. TEPAu caused mitochondrial swelling, increased permeability of the inner membrane, and the oxidation/hydrolysis of endogenous mitochondrial pyridine nucleotides. Addition of exogenous ATP slightly reversed the effects of TEPAu on pyridine nucleotides. TEPAu-induced mitochondrial alterations were reversed or inhibited by exposure to the sulfhydryl reducing agent, dithiothreitol. Also, the TEPAu-induced collapse of the mitochondrial membrane potential was partially inhibited by dibucaine, a non-specific inhibitor of phospholipases. These data suggest that TEPAu-induced mitochondrial dysfunction is sulfhydryl dependent. TEPAu-induced mitochondrial dysfunction results in dissipation of the potential difference across the inner mitochondrial membrane which inhibits mitochondrial oxidative phosphorylation. The mechanism by which TEPAu induces the collapse of the membrane potential may be mediated by a sulfhydryl-dependent increase in permeability of the inner membrane to protons.