Acute kidney injury following radical cystectomy and urinary diversion: predictors and associated morbidity

ABSTRACT Introduction: Acute kidney injury (AKI) after major surgeries is associated with significant morbidity and mortality. We aim to report incidence, predictors and associated comorbidities of AKI after radical cystectomy in a large cohort of patients. Materials and Methods: We conducted a retrospective analysis of 1000 patients who underwent open radical cystectomy in a tertiary referral center. Perioperative serum creatinine measurements were used to define AKI according to the RIFLE criteria (as Risk, Injury and Failure). The predictors of AKI after surgery were determined using univariate and multivariate analyses. Results: Out of 988 evaluable patients, AKI developed in 46 (4.7%). According to RIFLE criteria; AKI-Risk, AKI-Injury and AKI-Failure occurred in 26 (2.6%), 9 (0.9%) and 11 (1.1%) patients, respectively. Multivariate analysis showed that performing nephroureterectomy with cystectomy (Odds ratio [OR]: 4.3; 95% Confidence interval [CI]: 1.3-13.6; p=0.01) and the development of high grade complications (OR: 3.8; 95% CI 1.9-7.2; p<0.0001) were independently associated with AKI. Conclusions: AKI is a significant morbidity after radical cystectomy and the term should be included during routine cystectomy morbidity assessment.

Acute kidney injury following radical cystectomy and urinary diversion: predictors and associated morbidity.

INTRODUCTION: Acute kidney injury (AKI) after major surgeries is associated with significant morbidity and mortality. We aim to report incidence, predictors and associated comorbidities of AKI after radical cystectomy in a large cohort of patients. MATERIALS AND METHODS: We conducted a retrospective analysis of 1000 patients who underwent open radical cystectomy in a tertiary referral center. Perioperative serum creatinine measurements were used to define AKI according to the RIFLE criteria (as Risk, Injury and Failure). The predictors of AKI after surgery were determined using univariate and multivariate analyses. RESULTS: Out of 988 evaluable patients, AKI developed in 46 (4.7%). According to RIFLE criteria; AKI-Risk, AKI-Injury and AKI-Failure occurred in 26 (2.6%), 9 (0.9%) and 11 (1.1%) patients, respectively. Multivariate analysis showed that performing nephroureterectomy with cystectomy (Odds ratio [OR]: 4.3; 95% Confidence interval [CI]: 1.3-13.6; p=0.01) and the development of high grade complications (OR: 3.8; 95% CI 1.9-7.2; p<0.0001) were independently associated with AKI. CONCLUSIONS: AKI is a significant morbidity after radical cystectomy and the term should be included during routine cystectomy morbidity assessment.

Pharmacovigilance of patients with multiple myeloma being treated with bortezomib and/or thalidomide.

In order to evaluate the main adverse effects of drug protocols using bortezomib and/or thalidomide for the treatment of multiple myeloma, we conducted a prospective study. Data were collected through interviews, clinical observation, and from hospital records. A total of 59 patients were included. There was a predominance of females, 36 (61%) vs 23 (39%) males, and of whites, 49 (83.1%) vs 10 (16.9%) blacks. Age ranged from 40 to 94 years, with a median of 65 years (SD=11.6). Regarding staging at diagnosis, 27 (45.7%) patients were in stage III-A, with 12 (20.3%) patients having serum creatinine ≥2 mg/dL. The main adverse effects in the bortezomib treatment group (n=40) were: neutropenia (42.5%), diarrhea (47.5%), and peripheral neuropathy in 60% of cases, with no difference between the iv (n=26) and sc (n=14) administration routes (P=0.343). In the group treated with thalidomide (n=19), 31.6% had neutropenia, 47.4% constipation, and 68.4% peripheral neuropathy. Neutropenia was associated with the use of alkylating agents (P=0.038). Of the 3 patients who received bortezomib in combination with thalidomide, only 1 presented peripheral neuropathy (33.3%). Peripheral neuropathy was the main adverse effect of the protocols that used bortezomib or thalidomide, with a higher risk of neutropenia in those using alkylating agents. Improving the identification of adverse effects is critical in multiple myeloma patient care, as the patient shows improvements during treatment, and requires a rational and safe use of medicines.

Pharmacovigilance of patients with multiple myeloma being treated with bortezomib and/or thalidomide

In order to evaluate the main adverse effects of drug protocols using bortezomib and/or thalidomide for the treatment of multiple myeloma, we conducted a prospective study. Data were collected through interviews, clinical observation, and from hospital records. A total of 59 patients were included. There was a predominance of females, 36 (61%) vs 23 (39%) males, and of whites, 49 (83.1%) vs 10 (16.9%) blacks. Age ranged from 40 to 94 years, with a median of 65 years (SD=11.6). Regarding staging at diagnosis, 27 (45.7%) patients were in stage III-A, with 12 (20.3%) patients having serum creatinine ≥2 mg/dL. The main adverse effects in the bortezomib treatment group (n=40) were: neutropenia (42.5%), diarrhea (47.5%), and peripheral neuropathy in 60% of cases, with no difference between the iv (n=26) and sc (n=14) administration routes (P=0.343). In the group treated with thalidomide (n=19), 31.6% had neutropenia, 47.4% constipation, and 68.4% peripheral neuropathy. Neutropenia was associated with the use of alkylating agents (P=0.038). Of the 3 patients who received bortezomib in combination with thalidomide, only 1 presented peripheral neuropathy (33.3%). Peripheral neuropathy was the main adverse effect of the protocols that used bortezomib or thalidomide, with a higher risk of neutropenia in those using alkylating agents. Improving the identification of adverse effects is critical in multiple myeloma patient care, as the patient shows improvements during treatment, and requires a rational and safe use of medicines.

Risk factors for invasive mold diseases in allogeneic hematopoietic cell transplant recipients.

BACKGROUND: The epidemiology of and risk factors for invasive mold disease (IMD) among allogeneic hematopoietic cell transplant (HCT) recipients may vary according to the region. In this study, we sought to evaluate risk factors for IMD in our patient population. METHODS: Between May 2007 and July 2009, all HCT recipients from 8 Brazilian centers were followed prospectively until 1 year post transplant. Cases of IMD were classified as early (before day +40) or late (after day +40). Patients with IMD (cases) were compared with controls (patients without IMD) using univariate and multivariate Cox regression analysis. RESULTS: Among 345 HCT recipients, 28 IMDs were diagnosed. Risk factors for early IMD were acute myeloid leukemia (hazard ratio [HR] 2.95, 95% confidence interval [95% CI] 1.13-7.68, P = 0.03) and transplant with a human leukocyte antigen-mismatched donor (HR 3.38, 95% CI 1.18-9.68, P = 0.02), and for late IMD risk factors were lymphoma (HR 8.49, 95% CI 2.35-30.68, P = 0.001), cytomegalovirus reactivation (HR 5.51, 95% CI 1.15-26.47, P = 0.03), and neutropenia (HR 3.49, 95% CI 1.01-12.13, P = 0.049). CONCLUSION: The variables identified in this study may help to define risk groups, and to tailor special preventive measures to patients at higher risk to develop IMD.

Risk factors of hospital readmission after radical cystectomy and urinary diversion: analysis of a large contemporary series.

OBJECTIVES: To determine the incidence, risk factors and causes of hospital readmission in a large series of patients who underwent radical cystectomy (RC) and urinary diversion. PATIENTS AND METHODS: We retrospectively analysed the data of 1000 patients who underwent RC and urinary diversion between January 2004 and September 2009 in our tertiary referral centre. Patients stayed in hospital for 21 and 11 days for orthotopic and ileal conduit diversions, respectively. The primary outcome was the development of a complication requiring hospital readmission at ≤3 months (early) and >3 months (late). Causes of hospital readmissions were categorised according to frequency of readmissions. Predictors were determined using univariate and multivariate logistic regression models. RESULTS: In all, 895 patients were analysed excluding 105 patients because of perioperative mortality and loss to follow-up. Early and late readmissions occurred in 8.6% and 11% patients, respectively. The commonest causes of first readmission were upper urinary tract obstruction (UUO, 13%) and pyelonephritis (12.4%) followed by intestinal obstruction (11.9%) and metabolic acidosis (11.3%). The development of postoperative high-grade complications (odds ratio [OR] 1.955; 95% confidence interval [CI] 1.254-3.046; P = 0.003) and orthotopic bladder substitution (OR 1.585; 95% CI 1.095-2.295; P = 0.015) were independent predictors for overall hospital readmission after RC. Postoperative high-grade complications (OR 2.488; 95% CI 1.391-4.450; P = 0.002), orthotopic bladder substitution (OR 2.492; 95% CI 1.423-4.364; P = 0.001) and prolonged hospital stay (OR 1.964; 95% CI:1.166-3.308; P = 0.011) were independent predictors for early readmission while hypertension (OR 1.670; 95% CI 1.007-2.769; P = 0.047) was an independent predictor for late readmission. CONCLUSION: Hospital readmissions are a significant problem after RC. In the present study, UUO, pyelonephritis, metabolic acidosis and intestinal obstruction were the main causes of readmission. Orthotopic bladder substitution and development of postoperative high-grade complications were significant predictors for overall readmission.

Improvement in the outcome of invasive fusariosis in the last decade.

Invasive fusariosis (IF) has been associated with a poor prognosis. Although recent series have reported improved outcomes, the definition of optimal treatments remains controversial. The objective of this study was to evaluate changes in the outcome of IF. We retrospectively analysed 233 cases of IF from 11 countries, comparing demographics, clinical findings, treatment and outcome in two periods: 1985-2000 (period 1) and 2001-2011 (period 2). Most patients (92%) had haematological disease. Primary treatment with deoxycholate amphotericin B was more frequent in period 1 (63% vs. 30%, p <0.001), whereas voriconazole (32% vs. 2%, p <0.001) and combination therapies (18% vs. 1%, p <0.001) were more frequent in period 2. The 90-day probabilities of survival in periods 1 and 2 were 22% and 43%, respectively (p <0.001). In period 2, the 90-day probabilities of survival were 60% with voriconazole, 53% with a lipid formulation of amphotericin B, and 28% with deoxycholate amphotericin B (p 0.04). Variables associated with poor prognosis (death 90 days after the diagnosis of fusariosis) by multivariable analysis were: receipt of corticosteroids (hazard ratio (HR) 2.11, 95% CI 1.18-3.76, p 0.01), neutropenia at end of treatment (HR 2.70, 95% CI 1.57-4.65, p <0.001), and receipt of deoxycholate amphotericin B (HR 1.83, 95% CI 1.06-3.16, p 0.03). Treatment practices have changed over the last decade, with an increased use of voriconazole and combination therapies. There has been a 21% increase in survival rate in the last decade.

Extended step-advancement flap for avulsed amputated fingertip--a new technique to preserve finger length: case series.

PURPOSE: The conventional step-advancement flap does not restore fingertip length after avulsion amputation with projecting bone owing to the limited size of the distal triangular flap. To overcome this problem, the extended step advancement flap using the stepladder principle, described in this article, provides an extended distal triangular flap that can be wrapped around the projecting tip of the distal phalanx while avoiding longitudinal volar scarring. The purposes of this study were to present a modification of the original step-advancement technique and to report on results in 6 patients. METHODS: Between 2007 and 2009, 6 men (mean age, 29 y; range, 18-45 y) presented with a large projecting tip of exposed bone of the distal phalanx after avulsion injury. All 6 had reconstruction using the described technique. After surgery, the finger was immobilized with a splint, followed by rehabilitation. During the follow-up of 9 to 12 months, we clinically assessed flap-site skin quality, scar contractures, and finger mobility. We measured the finger's range of motion with a goniometer. Sensibility was evaluated using the static 2-point discrimination test. RESULTS: The postoperative course was uneventful. All flaps survived completely, except one that had mild marginal necrosis. We observed near-total active range of motion in all patients. The average static 2-point discrimination was 4 mm with a range of 3 to 5 mm. All patients resumed normal daily activities after 8 weeks. CONCLUSIONS: The extended step-advancement flap is ideal for closure of challenging fingertip amputation wounds because it maintains length and minimizes scars while providing a well-padded, sensate tip. It is a viable alternative to replantation of the fingertip. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Therapeutic hypothermia after cardiac arrest: a survey of practice in intensive care units in the United Kingdom.

A telephone survey was carried out on the use of hypothermia as part of the management of unconscious patients following cardiac arrest admitted to United Kingdom (UK) intensive care units (ICUs). All 256 UK ICUs listed in the Critical Care Services Manual 2004 were contacted to determine how many units have implemented therapeutic hypothermia for unconscious patients admitted following cardiac arrest, how it is implemented, and the reasons for non-implementation. Two hundred and forty-six (98.4%) ICUs agreed to participate. Sixty-seven (28.4%) ICUs have cooled patients after cardiac arrest, although the majority of these have treated fewer than 10 patients. The commonest reasons given for not using therapeutic hypothermia in this situation are logistical or resource issues, or the perceived lack of evidence or consensus within individual ICU teams.

Effects of blockade of NMDA receptors and NO synthase on the expression of associative and non-associative sensitization to effects of cocaine.

After repeated administration of psychostimulant drugs, a sensitization rather than a tolerance to the behavioral effects can be observed. In our own previous studies, it was shown that both blockade of NMDA glutamate receptors and inhibition of NO synthase selectively inhibited the expression of associative but not non-associative sensitization to D-amphetamine. The present experiments were performed in order to study whether a similar selective inhibition of expression of associative sensitization to cocaine can be observed after blockade of NMDA receptors by MK-801 or inhibition of NO synthase by L-NAME. MK-801 as well as L-NAME inhibited the locomotor activity in acutely cocaine-treated rats. Both drugs did not prevent the sensitization either in the associative or the non-associative group. The results suggest that the acute locomotor effects of cocaine were inhibited by both drugs whereas both the non-associative and the associative sensitization to locomotor effects were not inhibited by blockade of NMDA receptors or inhibition of NO synthase. Accordingly, the expression of neither type of sensitization to cocaine was inhibited by any of these drugs.

Bone morphogenetic protein-7 expression and activity in the human adult normal kidney is predominantly localized to the distal nephron.

Bone morphogenetic protein-7 (BMP)-7 plays an important role during fetal kidney development. In the adult, BMP-7 is most strongly expressed in the kidney compared to other organs, but the exact expression pattern as well as the function of BMP-7 is unclear. The major aim of the present study was to define which parts of the human kidney do physiologically express BMP-7 and which cells appear to be targets of BMP activity by showing phosphorylated BMP-receptor-associated Smads 1, 5, or 8 and inhibitor of differentiation factor 1 (ID1) expression. BMP-7 expression was localized by immunohistology to the epithelia of the distal tubule as well as the collecting ducts (CDs). Phospho-Smads 1/5/8 and ID1 expression largely colocalized with BMP-7 and was also localized in the epithelia of the distal tubule and the CDs. This was confirmed by polymerase chain reaction-based mRNA expression analysis. In vitro, proximal tubular cells (PTCs) expressed BMP receptors and BMP-receptor-associated Smads and were reactive to BMP-7. Our data indicate that BMP-7 expression in the adult human kidney appears to be more restricted than in the fetal situation and predominantly found in the distal nephron. Also, evidence of in vivo BMP signalling (i.e. phospho-Smads and ID1 expression) was found there. These findings suggest that BMP-7 plays a physiological role mostly in this part of the kidney. Still, as reported previously, PTCs are responsive to BMP-7, but presumably not in an autocrine or paracrine mode in normal adult kidneys.

Effects of blockade of glutamate NMDA receptors or of NO synthase on the development or the expression of associative or non-associative sensitization to locomotor activation by morphine.

The sensitization to the pharmacological actions of morphine is probably a critical factor in the addictive properties of this drug. A discrimination between associative and non-associative type of sensitization might be relevant for possible differences in drug effects on sensitization phenomena. Furthermore, blockade of NMDA receptors might lead to an inhibition of NO-synthesis, and, accordingly, both of these effects might influence sensitization phenomena in a similar way. Male Wistar rats were sensitized to morphine by administrations of 3 mg/kg of morphine i.p. on day 1, 3, 5, and 7 and saline on days 2, 4, and 6. In part of the animals, the administration of morphine was performed in association with conditional stimuli, CS (test cage plus an auditory and an olfactory stimulus), in the other part not (pseudoconditioned, PCS). On day 17, the sensitization was more pronounced in the CS than the PCS group. The effects of dizocilpine (MK-801; 0.1 mg/kg i.p.), a blocker of NMDA glutamate receptors, or of L-NAME (N(G)-nitro-L-arginine methylester; 10 mg/kg i.p.), a non-specific inhibitor of NO synthase and the effect of N(omega)-propyl-L-arginine (20 mg/kg i.p.), a specific inhibitor of neuronal NO synthase, on expression or development of sensitization to morphine was studied. Neither MK-801 nor L-NAME influenced the development of associative and non-associative behavioural sensitization to morphine. The expression of sensitization to morphine was not influenced by MK-801. L-NAME inhibited the expression of associative, but not of non-associative sensitization. Surprisingly, inhibition of neuronal NO synthase, did not influence the expression of associative sensitization. We suggest that NMDA receptors were not involved in development or expression of both types of sensitization. Furthermore, the manifestation of the associative, but not the non-associative sensitization to morphine appeared to be dependent on a type of NO synthase, which is not the neuronal NO synthase, but probably the inducible NOS.

Effects of dizocilpine [(+)-MK-801] on the expression of associative and non-associative sensitization to D-amphetamine.

Blockade of glutamate receptors of the NMDA type inhibits the sensitization to psychostimulant drugs, such as amphetamine, that occurs after repeated administration. Both associative (conditioning) and non-associative (pseudo-conditioning) mechanisms may contribute to sensitization phenomena. The aim of the present study was, thus, to determine which type of sensitization is influenced by blockade of NMDA-type receptors by examining the expression (manifestation) of sensitization. Locomotor activity was assessed and, in some experiments, extracellular dopamine in the nucleus accumbens was also assessed using in vivo microdialysis in non-anaesthetized, almost freely moving rats. Male albino Wistar rats of 225-250 g were given 1 mg/kg i.p. d-amphetamine every 2nd day for 7 days and with saline on the other days. Half the rats were exposed to d-amphetamine in the presence of conditioning stimuli (test cage, auditory and olfactory stimulus) and to saline in the home cage in absence of these stimuli, the other half were treated with saline and exposed to the conditioning stimuli and were placed into their home cages (without conditioning stimuli) after treatment with d-amphetamine. Ten days after the end of this treatment, both groups were exposed to the conditioning stimuli and half of each group were pretreated with dizocilpine [(+)-MK-801, 0.1 mg/kg i.p.], a blocker of NMDA receptors, 30 min before administration of 1 mg/kg d-amphetamine. (+)-MK-801 reduced the locomotor activity in rats sensitized associatively, but not in those sensitized non-associatively. It had no significant effect on spontaneous locomotor activity or that induced by acute administration of 1 mg/kg d-amphetamine. Similarly, (+)-MK-801 inhibited the increase in extracellular dopamine in the nucleus accumbens induced by the test dose of d-amphetamine in rats sensitized associatively but not non-associatively. The results suggest that the expression of both types of sensitization to d-amphetamine are dependent on glutamatergic NMDA mechanisms, although in different ways. Inhibition of sensitization, in particular of the associative type, might be of therapeutic value in drug dependence.

Novel synthesis and antifungal activity of pyrrole and pyrrolo[2,3-d]pyrimidine derivatives containing sulfonamido moieties.

Several sulfonamides containing pyrroles (2a-c, 6a-d, 8a-d), pyrrolo[2,3-d] pyrimidines (3a-c), acetanilides (11a-c) and tetrahydrobenzothiophenes (13a-c) were synthesized starting from N4-chloroacetylsulfanilamides (1a-d). The structures of synthesized compounds were elucidated by elemental analyses and spectral data. Compounds 2b, 3b, 6b, 8b and 8d exhibited a remarkable antifungal activity compared with the standard fungicide mycostatine.

Characterization of enzymes participating in carbonyl reduction of 4-methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK) in human placenta.

4-Methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK) has been identified as one of the strongest nitrosamine carcinogens in tobacco products in all species tested. Carbonyl reduction to 4-methylnitrosamino-1-(3-pyridyl)-1-butanol (NNAL) followed by glucuronosylation is considered to be the main detoxification pathway in humans. In previous investigations, we have identified a microsomal NNK carbonyl reductase as being identical to 11beta-hydroxysteroid dehydrogenase 1, a member of the short-chain dehydrogenase/reductase (SDR) superfamily. Recently, we provided evidence that carbonyl reduction of NNK does also take place in cytosol from mouse and human liver and lung. In human liver cytosol, carbonyl reductase, a SDR enzyme, and AKR1C1, AKR1C2 and AKR1C4 from the aldo-keto reductase (AKR) superfamily were demonstrated to be responsible for NNK reduction. Since NNK and/or its metabolites can diffuse through the placenta and reach fetal tissues, we now investigated NNK carbonyl reduction in the cytosolic fraction of human placenta in addition to that in microsomes. Concluding from the sensitivity to menadione, ethacrynic acid, rutin and quercitrin as specific inhibitors, mainly carbonyl reductase (EC 1.1.1.184) seems to perform this reaction in human placenta cytosol. The presence of carbonyl reductase was confirmed by RT-PCR. This is the first report to provide evidence that NNAL formation in placenta is mediated by carbonyl reductase.

Expression and NNK reducing activities of carbonyl reductase and 11beta-hydroxysteroid dehydrogenase type 1 in human lung.

The tobacco specific nitrosamine 4-methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK), which is found in high amounts in tobacco products, is believed to play an important role in lung cancer induction in smokers. NNK requires metabolic activation by cytochrome P450 mediated alpha-hydroxylation to exhibit its carcinogenic properties. On the other hand, NNK is inactivated by carbonyl reduction to its alcohol-equivalent 4-methylnitrosamino-1-(3-pyridyl)-1-butanol (NNAL) followed by glucuronidation and final excretion into urine or bile. Carbonyl reduction and alpha-hydroxylation are the predominant pathways in man, and it has been postulated that the extent of these competing pathways determines the individual susceptibility to lung cancer. Moreover, only a minor part of all habitual smokers develop lung cancer, suggesting the existence of susceptibility genes. Microsomal 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD 1) (EC 1.1.1.146) and cytosolic carbonyl reductase (CR) (EC 1.1.1.184) have been shown to be mainly responsible for NNAL formation in liver and lung. In the present study, we performed comparative investigations of human lung tissue samples from several patients with respect to the expression and activity of 11beta-HSD 1 and carbonyl reductase. We observed varying levels in 11beta-HSD 1 and carbonyl reductase expression in these patients, as revealed by RT-PCR and ELISA. Also, the tissue samples showed a different activity and inhibitor profile for both enzymes. According to our results, variations in the expression and activity of NNK carbonyl reducing enzymes may constitute a major determinant in the overall NNK detoxification capacity and thus may be linked to the great differences observed in the individual susceptibility of tobacco-smoke related lung cancer.

Comparative diagnostic values of grey-scale USS versus CT scan in the primary management of gynaecological pelvic mass with emphasis on ovarian cancer detection and staging.

Thirty-one consecutive patients with clinical pelvic masses suspected to be gynaecological in origin were initially investigated by transabdominal grey-scale ultrasound (TAUS) and then by computed tomography (CT) prior to surgery and or chemotherapy. Retrospective comparative review of the reports of the two imaging methods was carried out on each patient and then correlated with surgical findings and histopathology report. The diagnostic potentials of the two imaging methods with respect to ovarian cancer detection and staging were particularly emphasised. The results were analysed and compared with published results of similar studies in the literature. Compared with TAUS we found CT scan more sensitive in making an overall presumptive diagnosis of pelvic mass (15/31, 48% vs. 9/31, 29%). The sensitivity of CT scan for all ovarian cancer detection was greater than that of TAUS (5/6, 83% vs. 4/6, 67%) but TAUS was more specific. The false negative and false positive values for cancer detection were comparable. Both methods were equally efficacious in detecting and staging advanced ovarian cancer cases (4/4, 100%). Visualisation of the ovaries occurred more readily with TAUS, which in addition offered a more precise assessment of ovarian tumour size. There were no significant differences in the two methods regarding tumour localisation (organ of origin), characterisation and the details of descriptive report when no presumptive diagnosis is offered. Overall CT did not offer significant additional features and did not result in changes in management plan in any of the patients reviewed. The marginal benefit of CT scan over TAUS will not warrant its routine usage in the diagnosis of gynaecological pelvic mass. Our findings largely reflected the conclusions of published reports in the literature.

Purification and characterization of oxidoreductases-catalyzing carbonyl reduction of the tobacco-specific nitrosamine 4-methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK) in human liver cytosol.

1. Four enzymes were purified to homogeneity from human liver cytosol and were demonstrated to be responsible for carbonyl reduction of the tobacco-specific nitrosamine 4-methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK). 2. Carbonyl reductase (EC 1.1.1.184), a member of the short-chain dehydrogenase/reductase (SDR) superfamily, was compared with three isoenzymes of the aldo-keto reductase (AKR) superfamily in terms of enzyme kinetics, co-substrate dependence and inhibition pattern. 3. AKR1C1, 1C2 and 1C4, previously designated as dihydrodiol dehydrogenases (DD1, DD2 and DD4), showed lower K(m) (0.2, 0.3 and 0.8 mM respectively) than did carbonyl reductase (7 mM), whereas carbonyl reductase exhibited the highest enzyme efficiency (Vmax/K(m)) for NNK. Multiplication of enzyme efficiencies with the relative quantities of individual enzymes in cytosol resulted in a rough estimate of their contributions to total alcohol metabolite formation. These were approximately 60% for carbonyl reductase, 20% each for AKR1C1 and 1C2, and 1% for AKR1C4. 4. Except for AKR1C4, the enzymes had a strong preference for NADPH over NADH, and the highest activities were measured with an NADPH-regenerating system. Carbonyl reductase activity was extensively inhibited by menadione, rutin and quercitrin, whereas medroxyprogesterone acetate, phenolphthalein and flufenamic acid were potent inhibitors of AKR1C1, 1C2 and 1C4. 5. In conclusion, cytosolic members of the SDR and AKR superfamilies contribute to reductive NNK detoxification in human liver, the enzymes responsible being carbonyl reductase and aldoketo reductases of the AKRIC subfamily.