[Considerations for quality assurance of discussions with relatives in direct association with organ donation]

BACKGROUND

Discussions with relatives are relevant and crucial aspects of the organ donation process and contribute to a consolidated and sustainable decision by the families of the deceased. Despite the great importance of family care, there is no systematic analysis of the quality of this communication, in contrast to the diagnosis of irreversible loss of brain function, organ retrieval and organ transplantation. For this reason, organ donation experts were interviewed about recurring characteristics of communication with relatives of the deceased. The aim of this qualitative study was to define criteria for the assessment of the structure and quality of the communication process with relatives for internal quality management in Germany.

METHODS

Based on a systematic literature review and with the help of the 5‑stage S²PS² (system for creating a questionnaire) procedure according to Kruse, interview guidelines were initially developed. As a second step, in guideline-based interviews 10 experienced organ donation experts were questioned about structural, procedural and ethical aspects of their discussions with relatives. Following the interviews, a software-based qualitative content analysis was carried out with a combined inductive-deductive category system. Finally, the first quality assurance measures for the interviews with relatives were developed in a multistep process, closely following the methodological principles V1.1 of the Institute for Quality Assurance and Transparency in Health Care (IQTIG). The individual research steps were accompanied by an expert group consisting of physicians, nurses, theologians and ethicists utilizing an anonymous Delphi procedure.

RESULTS

In the qualitative content analysis, 5 main categories with 30 subcategories on quality relevant aspects could be identified (including, standardization and technique of conversation, interview framework and context factors, professional expertise of the interviewers, wishes of the organ donation experts). On this basis, 6 criteria for the structural quality and 7 criteria for the process quality of the discussions with relatives were formulated and summarized in a respective quality bundle. These criteria address, among other things, interprofessional communication, structured training concepts, regular further training of all team members, use of standardized communication and counselling strategies as well as documented preliminary meetings and debriefings, including supervising elements. They emphasize interdisciplinary professionalism and process management in a protected environment as well as quality assured communication and documentation. Recommendations were made for expanding the existing documentation for the organ donation process and for documenting the preliminary meetings and debriefings.

CONCLUSION

Recurring communication and process characteristics as well as requirements for the members of the treatment team who conduct the conversation can be identified for the interviews with relatives, which show potential for improvement to various degrees. This justifies the structured derivation of a quality bundle for the structural and process quality family care related to organ donation, which should enable a low-threshold entry into an institution internal systematic quality assessment of communication with relatives in Germany. Due to the different legal, medical and social specifics in an international context, the study results cannot be directly transferred to other countries.

In vivo MRI mapping of iron oxide-labeled stem cells transplanted in the heart

In various stem cell therapy approaches poor cell survival has been recognized as an important factor limiting therapeutic efficacy. Therefore noninvasive monitoring of cell fate is warranted for developing clinically effective stem cell therapy. In this study we investigated the use of voxel-based R₂ mapping as a tool to monitor the fate of iron oxide-labeled cells in the myocardium. Mesenchymal stem cells were transduced with the luciferase gene, labeled with ferumoxide particles and injected in the myocardium of healthy rats. Cell fate was monitored over a period of 8 weeks by bioluminescence and quantitative magnetic resonance imaging. Bioluminescence signal increased during the first week followed by a steep decrease to undetectable levels during the second week. MR imaging showed a sharp increase in R₂ values shortly after injection at the injection site, followed by a very gradual decrease of R₂ over a period of 8 weeks. No difference in the appearances on R₂-weighted images was observed between living and dead cells over the entire time period studied. No significant correlation between the bioluminescence optical data and R₂ values was observed and quantitative R₂ mapping appeared not suitable for the in vivo assessment of stem cell. These results do not follow previous in vitro reports where it was proposed that living cells may be distinguished from dead cells on the basis of the R₂ relaxivities (intracellular and extracellular iron oxides). Cell proliferation, cell migration, cell death, extracellular superparamagnetic iron oxide dispersion and aggregation exhibit different relaxivities. In vivo these processes happen simultaneously, making quantification very complex, if not impossible.

Indirect CD4+ TH1 response, antidonor antibodies and diffuse C4d graft deposits in long-term recipients conditioned by donor antigens priming

Priming of recipients by DST induces long-term survival of mismatched allografts in adult rats. Despite these recipients developing inducible T regulatory cells able to transfer long-term graft survival to a secondary host, a state of chronic rejection is also observed. We revisited the molecular donor MHC targets of the cellular response in acute rejection and analyzed the cellular and humoral responses in recipients with long-term graft survival following transplantation. We found three immunodominant peptides, all derived from LEW.1W RT1.D(u) molecules to be involved in acute rejection of grafts from unmodified LEW.1A recipients. Although the direct pathway of allorecognition was reduced in DST-treated recipients, the early CD4+ indirect pathway response to dominant peptides was almost unimpaired. We also detected early and sustained antidonor class I and II antibody subtypes with diffuse C4d deposits on graft vessels. Finally, long-term accepted grafts displayed leukocyte infiltration, endarteritis and fibrosis, which evolved toward vascular narrowing at day 100. Altogether, these data suggest that the chronic graft lesions developed in long-term graft recipients are the result of progressive humoral injury associated with a persisting indirect T helper response. These features may represent a useful model for understanding and manipulating chronic active antibody-mediated rejection in human.

Can baseline complete geriatric assessment (CGA) predict toxicity in elderly non-small cell lung cancer (NSCLC) patients (pts) receiving combination chemotherapy? Results from the first 100 pts in the prospective multicenter NVALT-3 study

7537

Background: Nearly 50% of NSCLC pts are aged over 70 years, but only few receive combination chemotherapy. Undertreatment results from a fear of associated toxicities. CGA may predict which patients are prone to toxicities, and thus allow patient selection for such treatment. Methods: A total of 182 NSCLC pts = 70 years with stage IIIb/IV disease were randomized to 4 cycles carboplatin/gemcitabine (group 1) or carboplatin/paclitaxel (group 2). Before treatment, CGA was performed using the following instruments: WHO Performance Scale (PS), Charlson comorbidity index (CCI), Cumulative Illness Rating Scale-Geriatrics (CIRS-G), Activities of Daily Living (ADL), Instrumental Activities of Daily Living (IADL), Timed “Up&Go” (TUG), Mini-Mental State Examination (MMSE), Geriatric Depression Score (GDS-15), Groningen Frailty Indicator (GFI). Toxicity was scored using NCI-CTC v2. Toxicity related outcomes were defined as all grade III/IV toxicities, toxicity related SAEs, = grade II neurological toxicity and the ability to finish all cycles. Results: In the first 100 pts mean age was 75 yrs (range 70–85). PS was 0 in 30%, 1 in 56% and 2 in 14%. 57% completed all 4 cycles. 11% stopped treatment prematurely due to toxicity and 12% due to PD. Overall, grade III/IV toxicity occurred in 66% of pts, toxicity related SAEs in 12%, and 35% experienced = grade 2 neurological toxicity (n=13 group 1, n=22 group 2). Median (range) baseline CGA scores were as follows: CCI 1.0 (0–7), CIRS-G 3.0 (0–14), ADL independent 72%, IADL independent 50%, TUG 12.0 sec.(5–40), MMSE 29 (19–30), GDS-15 normal (score 0–4) 71%, GFI 3.0 (0–10). Multivariate logistic regression indicated that, for experiencing toxicity related SAEs CIRS-G provided extra information, for experiencing neurological toxicities MMSE was predictive and for finishing all cycles, IADL provided extra information in addition to PS and stage. Conclusions: CGA can predict toxicity in elderly NSCLC pts receiving combination chemotherapy. Data on all 182 patients will be presented.

No significant financial relationships to disclose.

[Comprehensive range of services for general hospitals in the area of organ donation nearly doubles the number of donors in 2 years with a simultaneously economical process]

To overcome the donor shortage, any potential donor resource must be detected. By establishing a professional service for peripheral hospitals, the numbers of donors available in small hospitals could be nearly doubled: 85% of all donors in our region come from nonuniversity hospitals. By using total quality management techniques, the time requirements for organ donation after confirmation of brain-death and given consent could be reduced to 6 h.

[Transplantation and organ donation in Germany]

Since the first kidney transplantation in Germany 1963 organ transplantation progressed in quality and quantity. Despite a very successful development the national transplant program stagnates since 1990 with even regression in renal transplantation. As number of patients in need of renal replacement therapy has grown now to about 40,000 it is of great importance to improve the situation especially in regard to kidney transplantation.

Mechanisms for the hepatic uptake and biliary excretion of tributylmethylammonium: studies with rat liver plasma membrane vesicles

Hepatic organic cation transport in vitro, using tetraethylammonium (TEA) as a substrate, consists of at least two steps: sinusoidal uptake is stimulated by an inside-negative membrane potential and canalicular membrane transport is mediated by organic cation:H+ exchange (Moseley et al., 1992b). In vivo, however, TEA is poorly excreted into bile. In contrast, larger, more hydrophobic organic cations, such as tributylmethylammonium (TBuMA), undergo significant hepatobiliary excretion. To better characterize hepatic organic cation transport, TBuMA transport was examined in rat canalicular liver plasma membrane (cLPM) and basolateral liver plasma membrane (bILPM) vesicles. In cLPM vesicles, under voltage-clamped conditions, an outwardly directed H+ gradient stimulated [3H]TBuMA uptake consistent with electroneutral TBuMA:H+ exchange; H(+)-dependent [3H]TBuMA uptake was not the result of a H+ diffusion potential. In the absence of a H+ gradient, intravesicular TBuMA trans-stimulated [3H]TBuMA uptake. Substrates for renal and hepatic organic cation:H+ exchange cis-inhibited H(+)-dependent [3H]TBuMA uptake. No ATP-dependent [3H]TBuMA uptake was detected in cLPM vesicles, and the P-glycoprotein substrate, daunomycin, did not cis-inhibit H(+)-dependent [3H]TBuMA uptake. Carrier-mediated [3H]TBuMA uptake exhibited saturability (Km of 0.5 mM and Vmax of 0.5 nmol/mg prot/5 s). In bILPM vesicles, in contrast, a valinomycin-induced intravesicular-negative K+ diffusion potential stimulated [3H]TBuMA uptake. These findings suggest that hepatic transport of TBuMA is similar to TEA but fundamentally different from that of P-glycoprotein substrates, indicating the involvement of at least two separate processes for the hepatobiliary excretion of organic cationic drugs.

Further advances of chronic renal replacement therapy in eastern Germany, 1994 versus 1989

Unlike the other former Soviet-block countries, Eastern Germany/the "GDR", had the opportunity to the re-unification with a highly developed western country, the Federal Republic of (West) Germany in 1990. In order to record the following rapid improvements in renal replacement therapy, we performed our own survey in Eastern Germany--excluding Eastern Berlin--by questionnaire, comparing the years 1989/December, and 1994/December. 112 of the 113 dialysis facilities for adult regular dialysis patients replied to our questionnaire (99%). From 1989 to 1994, the number of dialysis centers increased from 53 to 113 (-->213%), reaching 7.9 centres p.m.p. Of these facilities, 29% were hospital centers, 48% were private dialysis units, and 23% were run by nonprofit dialysis organizations. The number of dialysis stations increased from 602 to 1,719 (-->286%), i.e. 120 stations p.m.p. The number of patients in regular dialysis treatment rose from 2,127 to 5,335 (-->251%), that means a prevalence of 373 patients p.m.p. In 1989, 67 new patients (p.m.p.) had been accepted for maintenance treatment (incidence), in contrast to 130 new patients p.m.p. in 1994 (-->194%), now under the conditions of unlimited accessibility to dialysis treatment. Questions referring to this point--the incidence of new patients--were only asked in Thüringen (2.5 mio. inhabitants). Alternative treatment modalities became feasible under the new conditions in Eastern Germany. In contrast to 99% hemodialysis patients in December 1989, at the end of 1994 92.8% of the patients were treated by hemodialysis, 2.0% by hemofiltration, and 5.2% by peritoneal dialysis, predominantly CAPD.(ABSTRACT TRUNCATED AT 250 WORDS)

Prolongation of allogeneic heart graft survival in rats by administration of a peptide (a.a. 75-84) from the alpha 1 helix of the first domain of HLA-B7 01

Allospecific T lymphocytes mediate graft rejection through specific, direct or indirect, recognition of processed determinants of foreign MHC class I molecules. Small synthetic peptides derived from highly conserved sequences of the alpha 1 helix of the first domain of certain MHC class I molecules have been shown to inhibit CTL responses in vitro and to prolong graft survival in rats when combined with subtherapeutic doses of cyclosporine. Here, we report that the survival of LEW.1W heart allografts was significantly prolonged when transplanted into congenic LEW.1A recipients treated only with a peptide corresponding to residues 75-84 of the human HLA-B7-01 molecule (B7.75-84) before transplantation. The experimental value for mean survival time (+/- SD) in untreated recipients was 13 +/- 6 days and in peptide-treated recipients was 42 +/- 27 days (P < 0.002). A total of 64% of treated recipients had a functioning graft at 30 days, while grafts were rejected in all rats belonging to the control group within this time. Within graft-infiltrating leukocytes (GIL) in B7.75-84-treated animals, the proportion of T cells was significantly lower and that of CD5-/TCR alpha beta-/CD16-/CD8+ and MHC class II+ cells concomitantly increased, as compared with nontreated animals. GIL from B7.75-84-treated animals also exhibited a dramatic decrease (approximately 70%) of allospecific and spontaneous (NK) cytotoxic activity, whereas their proliferation and IL-2 production were similar in both experimental groups. The IFN-gamma, IL-2, and IL-10 mRNA levels from GIL from peptide-treated recipients were similar to levels of controls, reflecting a state of activation of GIL. Perforin and granzyme A mRNA, the level of which may be modulated parallel to impaired cytotoxic functions, were at similar levels in both experimental groups. These data demonstrate that B7.75-84 significantly prolongs graft survival in LEW.1A rats when given as a single agent and suggests that a specifically decreased cytotoxic response (allospecific and spontaneous) plays a major role.

Decreased anti-donor major histocompatibility complex class I and increased class II alloantibody response in allograft tolerance in adult rats

Permanent tolerance to allografts can be induced in adult rats by donor-specific transfusions (DST) prior to transplantation. We have previously reported, in a model of heart allograft, the presence of a heavy leukocyte infiltrate, in the allograft which displayed a strong allospecific cytotoxicity when tested in vitro against donor cells, and a strong accumulation of mRNA for granzyme A and perforin in vivo. In contrast, there was a major decrease in the accumulation of mRNA for interleukin-2 and interferon-gamma. These results suggested that the DST-induced tolerance was associated with a decrease in type-1 T helper (Th1) cell function. The major role of preformed antibodies in xeno and allorejection is clearly established. Nevertheless, the consequences of alloantibody production in acute rejection and tolerance induction remains to be elucidated. We here analyze the alloantibody response in rejecting and DST-treated recipients. We show that, after transplantation, tolerant recipients, in contrast to rejecting ones, mount a low IgM alloresponse that switches to low IgG production. Detailed analysis of IgG alloantibodies in DST-treated recipients revealed that their production decrease was not equally distributed. Whereas rejecting animals mounted a strong anti-class I and II IgG alloantibody response, DST-treated recipients produced anti-class II and low titers of anti-class I IgG alloantibodies. Furthermore, among IgG subclasses, tolerant recipients predominantly produced IgG2a, a profile which, in the rat, is compatible with a Th2-controlled response. Finally, the passive transfer of immune serum from rejecting animals to DST-treated recipients could abrogate the tolerance. We suggest that the absence of anti-class I alloantibodies combined with preserved and/or increased anti-class II production plays a major role in graft tolerance in this model. These results reinforced the role of alloantibodies in rejection and in induction of tolerance.

Modulators of the protein kinase C system influence biliary excretion of cationic drugs

To investigate whether hepatobiliary transport of organic cations is under regulatory control, we studied transport of tri-n-butylmethylammonium in the isolated perfused rat liver and in isolated rat hepatocytes. Transport was investigated in the presence of modulators of the protein kinase C and the cyclic AMP second-messenger system. In the isolated perfused rat liver, it was observed that compounds modulating protein kinase C activity clearly affected the biliary excretion process of the cation tri-n-butylmethylammonium. Phorbol 12-myristate 13-acetate, a compound that directly stimulates protein kinase C, elevated the biliary excretion rate of tri-n-butylmethylammonium in a concentration-dependent manner, reaching a twofold increase at 60 nmol/L of the phorbol ester. The inactive derivative 4 alpha-phorbol 12, 13-didecanoate (60 nmol/L) did not show any effect. Vasopressin (48 nmol/L), a receptor-mediated activator of protein kinase C, stimulated the excretion rate of the cation by about 50%. Staurosporin (1 mumol/L), an inhibitor of protein kinase C, clearly decreased the biliary excretion rate of the cation and also blocked its stimulation by phorbol 12-myristate 13-acetate. Neither phorbol 12-myristate 13-acetate nor vasopressin (at concentrations ranging from 10(-9) to 10(-6) mol/L) affected the initial uptake velocity of tri-n-butylmethylammonium in isolated hepatocytes and isolated perfused livers, whereas staurosporin (1 mumol/L) showed only a modest inhibition of the uptake of the cation. It is inferred that the effect of protein kinase C modulators on hepatobiliary transport of organic cations occurs at the level of carrier-mediated transport in the canalicular membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Obstetrics and childbirth at the Aitape Health Centre, Papua New Guinea

Routinely collected obstetric data at the Aitape Health Centre, Papua New Guinea over the years 1986, 1988 and 1989 were analyzed and compared with figures from western New Guinea of about thirty years ago and with those of rural African hospitals. Data from 924 deliveries were analyzed. 30% were born before arrival (BBA). The number of abnormal deliveries was high. This was in part due to the high frequency of twin births (4.5%). Among the BBAs puerperal sepsis and stillbirth were significantly higher than among those who delivered in the health centre. The stillbirth frequency was 3.4%. The sex ratio male:female at birth was 120.9. The large number of retained placentae with manual removal (5.2%) was related to high parity; 33.5% of the women delivering at the health centre were para-4 or more. 20% of male and 24% of female newborns had low birthweight (less than 2500g).

arcD, the first gene of the arc operon for anaerobic arginine catabolism in Pseudomonas aeruginosa, encodes an arginine-ornithine exchanger

In the absence of oxygen and nitrate, Pseudomonas aeruginosa metabolizes arginine via the arginine deiminase pathway, which allows slow growth on rich media. The conversion of arginine to ornithine, CO2, and NH3 is coupled to the production of ATP from ADP. The enzymes of the arginine deiminase pathway are organized in the arcDABC operon. The arcD gene encodes a hydrophobic polytopic membrane protein. Translocation of arginine and ornithine in membrane vesicles derived from an Escherichia coli strain harboring a recombinant plasmid carrying the arcD gene was studied. Arginine and ornithine uptake was coupled to the proton motive force with a bias toward the transmembrane electrical potential. Accumulated ornithine was readily exchangeable for external arginine or lysine. The exchange was several orders of magnitude faster than proton motive force-driven transport. The ArcD protein was reconstituted in proteoliposomes after detergent solubilization of membrane vesicles. These proteoliposomes mediate a stoichiometric exchange between arginine and ornithine. It is concluded that the ArcD protein is a transport system that catalyzes an electroneutral exchange between arginine and ornithine to allow high-efficiency energy conversion in the arginine deiminase pathway.

Mathematical modelling of lipid production by oleaginous yeasts in continuous cultures

A mathematical model was constructed to describe the influence of the carbon to nitrogen ratio (C/N-ratio) of the growth medium on lipid production by oleaginous yeasts. To test this model and to determine some relevant model parameters, the oleaginous yeast Apiotrichum curvatum ATCC 20509 was grown in continuous cultures at various C/N-ratios and dilution rates. It appeared that when nitrogen is limiting for the formation of biomass, the remaining glucose can be converted to storage carbohydrate and storage lipid. No clear dependence of carbohydrate yield on the C/N-ratio could be demonstrated, but lipid yield increased gradually with increasing C/N-ratios. The maximal dilution rate for lipid producing yeast cells appeared to be optimal at relatively low C/N-ratios. It can be concluded that the experimental results fitted well with the mathematical model. By using this model, lipid yield and lipid production rate can be calculated at any C/N-ratio of the growth medium and optimum operation conditions can be predicted for the production of microbial lipids.

Isolation and structural characterization of the equine erythrocyte receptor for enterotoxigenic Escherichia coli K99 fimbrial adhesin

The erythrocyte receptor for Escherichia coli K99 fimbrial adhesin was isolated from equine erythrocytes and characterized as Neu5Gc-alpha(2----3)-Galp-beta(1----4)-GLcp-beta(1----1)-Ceramide. This glycolipid acted as the receptor for K99 by four different experimental approaches: inhibition of equine erythrocyte hemagglutination by preincubation of K99-positive bacteria or purified K99 fimbriae with the isolated glycolipid; inhibition of attachment of K99-positive bacteria to porcine intestinal epithelial cells in the presence of the isolated glycolipid; induction of binding of K99-positive bacteria or purified K99 fimbriae to normally unreactive guinea pig erythrocytes by coating these cells with the isolated glycolipid; and isolation of the receptor by affinity chromatography with K99 coupled to CNBr-activated Sepharose 4B, indicating a strong interaction between K99 and the isolated glycolipid.

Mechanism of action of the copper(I) complex of 2,9-dimethyl-1,10-phenanthroline on Mycoplasma gallisepticum

Evidence was found that the inhibitory action of Cu(DMP)2NO3, the copper(I) complex of 2,9-dimethyl-1,10-phenanthroline (DMP), on Mycoplasma gallisepticum is a consequence of the ultimate toxicity of copper, and not that of the ligand, DMP. From uptake studies with radiolabeled 67Cu and [14C]DMP, we concluded that significantly more copper than DMP is bound to the mycoplasmal cell. It appeared that dissociation of Cu(DMP)2+ occurred shortly after interaction with the cell membrane. Copper was transported across the cytoplasmic membrane. A strong dependence of copper uptake on the incubation medium was observed in the absence of DMP. The main function of the ligand DMP appeared to be as a vehicle for the transport of copper from nontoxic copper-medium complexes to membrane-buried cellular ligands.

Mode of action of the copper(I) complex of 2,9-dimethyl-1,10-phenanthroline on Mycoplasma gallisepticum

Various physiological important activities of Mycoplasma gallisepticum were inhibited by the copper(I) complex of 2,9-dimethyl-1,10-phenanthroline [Cu(DMP)2NO3]. The energy-yielding metabolism was inhibited because the conversion of pyruvate into lactate was found to be blocked by Cu(DMP)2NO3, indicating a selective inhibition of lactate dehydrogenase. Also, the production rate of acetate and the rate of oxygen uptake by whole cells of M. gallisepticum appeared to be strongly decreased. Experiments with crude cell extracts showed an inhibition of reduced nicotinamide adenine dinucleotide (NADH) oxidase by Cu(DMP)2NO3 and an even stronger inhibition of NADH oxidase and lactate dehydrogenase by CuSO4. No preferential inhibition of adenosine 5'-triphosphatase and pyruvate kinase was found. Investigations on the influence of Cu(DMP)2NO3 on deoxyribonucleic acid, ribonucleic acid, and protein synthesis with growing cells of M. gallisepticum showed a selective inhibition of the incorporation of [14C]thymidine into deoxyribonucleic acid. Cu(DMP)2NO3 induced a decrease in the total amount of accessible sulfhydryl groups of whole cells of M. gallisepticum, indicating that the observed diverse toxicity of Cu(DMP)2NO3 may be associated with the interaction of copper ions with protein sulfhydryl groups.

Mode of action of copper complexes of some 2,2'-bipyridyl analogs on Paracoccus denitrificans

Copper complexes of 2,2'-bipyridyl and related compounds and CuSO4 inhibited the growth of paracoccus denitrificans. The copper(I) complex of 2,9-dimethyl-1,10-phenanthroline [Cu(DMP)2NO3] showed the highest activity, whereas the copper(II) complex of 1,10-phenanthroline and CuSO4 inhibited the growth to a lesser extent. The uncomplexed ligands (1,10-phenanthroline and 2,9-dimethyl-1,10-phenanthroline) showed little activity, but in the presence of noninhibitory amounts of CuSO4 this activity increased markedly. Copper ions therefore proved to be essential for the growth-inhibitor effect. The extent of inhibition appeared to be strongly dependent on the initial cell density and on the growth medium. No selective inhibition of deoxyribonucleic acid, ribonucleic acid, or protein synthesis was observed with Cu(DMP)2NO3. Respiratory electron transport of P. denitrificans appeared to be strongly inhibited by Cu(DMP)2NO3 and to a somewhat lesser extent by CuSO4. Both aerobic and anaerobic respirations were inhibited to the same extent, and from the cytochrome redox kinetics it is concluded that the site of this inhibition in the respiratory electron transport chain must be located before cytochrome b. Cu(DMP)2NO3 did not significantly influence the H+/O ratio with whole cells of P. denitrificans, suggesting that the efficiency of oxidative phosphorylation is not affected by CU(DMP)2NO3. Growing cultures of P. denitrificans showed a decrease in intracellular potassium ion content in the presence of increasing amounts of Cu(DMP)2NO3. It is concluded that interference with the cytoplasmic membrane, resulting in inhibition of respiratory electron transport, probably constitutes the main mode of action of copper complexes of 2,2'-bipyridyl analogs on P. denitrificans.