Pushing the Limits in Real-Time Measurements of Quantum Dynamics

Time-resolved studies of quantum systems are the key to understanding quantum dynamics at its core. The real-time measurement of individual quantum numbers as they switch between certain discrete values, well known as a "random telegraph signal," is expected to yield maximal physical insight. However, the signal suffers from both systematic errors, such as a limited time resolution and noise from the measurement apparatus, as well as statistical errors due to a limited amount of data. Here we demonstrate that an evaluation scheme based on factorial cumulants can reduce the influence of such errors by orders of magnitude. The error resilience is supported by a general theory for the detection errors as well as experimental data of single-electron tunneling through a self-assembled quantum dot. Thus, factorial cumulants push the limits in the analysis of random telegraph data, which represent a wide class of experiments in physics, chemistry, engineering, and life sciences.

Digital health for optimal supportive care in oncology: benefits, limits, and future perspectives

BACKGROUND

Digital health provides solutions that capture patient-reported outcomes (PROs) and allows symptom monitoring and patient management. Digital therapeutics is the provision to patients of evidence-based therapeutic interventions through software applications aimed at prevention, monitoring, management, and treatment of symptoms and diseases or for treatment optimization. The digital health solutions collecting PROs address many unmet needs, including access to care and reassurance, increase in adherence and treatment efficacy, and decrease in hospitalizations. With current developments in oncology including increased availability of oral drugs and reduced availability of healthcare professionals, these solutions offer an innovative approach to optimize healthcare resource utilization.

DESIGN

This scoping review clarifies the role and impact of the digital health solutions in oncology supportive care, with a view of the current segmentation according to their technical features (connection to sensors, PRO collection, remote monitoring, self-management in real time…), and identifies evidence from clinical studies published about their benefits and limitations and drivers and barriers to adoption. A qualitative summary is presented.

RESULTS

Sixty-six studies were identified and included in the qualitative synthesis. Studies supported the use of 38 digital health solutions collecting ePROs and allowing remote monitoring, with benefits to patients regarding symptom reporting and management, reduction in symptom distress, decrease in unplanned hospitalizations and related costs and improved quality of life and survival. Among those 38 solutions 21 provided patient self-management with impactful symptom support, improvement of QoL, usefulness and reassurance. Principal challenges are in developing and implementing digital solutions to suit most patients, while ensuring patient compliance and adaptability for use in different healthcare systems and living environments.

CONCLUSIONS

There is growing evidence that digital health collecting ePROs provide benefits to patients related to clinical and health economic endpoints. These digital solutions can be integrated into routine supportive care in oncology practice to provide improved patient-centered care.

Optical Detection of Single-Electron Tunneling into a Semiconductor Quantum Dot

The maximum information of a dynamic quantum system is given by real-time detection of every quantum event, where the ultimate challenge is a stable, sensitive detector with high bandwidth. All physical information can then be drawn from a statistical analysis of the time traces. We demonstrate here an optical detection scheme based on the time-resolved resonance fluorescence on a single quantum dot. Single-electron resolution with high signal-to-noise ratio (4σ confidence) and high bandwidth of 10 kHz make it possible to record the individual quantum events of the transport dynamics. Full counting statistics with factorial cumulants gives access to the nonequilibrium dynamics of spin relaxation of a singly charged dot (γ_{↑↓}=3  ms^{-1}), even in an equilibrium transport measurement.

Craniomaxillofacial morphology alterations in children, adolescents and adults with neurofibromatosis 1: A cone beam computed tomography analysis of a Brazilian sample

BACKGROUND

Oral manifestations are common in neurofibromatosis 1 (NF1), and include jaws and teeth alterations. Our aim was to investigate the craniomaxillofacial morphology of Brazilian children, adolescents and adults with NF1 using cone beam computed tomography.

MATERIAL AND METHODS

This study was conducted with 36 Brazilian individuals with NF1 with ages ranging from 4 to 75. The participants were submitted to anamnesis, extra and intraoral exam and cephalometric analysis using cone beam computed tomography. Height of the NF1 individuals was compared to the length of jaws and skull base. The results of the cephalometric measurements of the NF1 group were compared with a control group paired by age, gender and skin color.

RESULTS

Individuals with NF1 had lower maxillary length (p<0.0001), lower mandibular length (p<0.0001), lower skull base length (p<0.0001). In children and adolescents, the mandible was more posteriorly positioned (p=0.01), when compared with the control group. There was no association between jaws and skull base length with the height of the individuals with NF1.

CONCLUSIONS

Brazilian children, adolescents and adults with NF1 have short mandible, maxilla and skull base. Moreover, children and adolescents present mandibular retrusion.

Optical Blocking of Electron Tunneling into a Single Self-Assembled Quantum Dot

Time-resolved resonance fluorescence (RF) is used to analyze electron tunneling between a single self-assembled quantum dot (QD) and an electron reservoir. In equilibrium, the RF intensity reflects the average electron occupation of the QD and exhibits a gate voltage dependence that is given by the Fermi distribution in the reservoir. In the time-resolved signal, however, we find that the relaxation rate for electron tunneling is, surprisingly, independent of the occupation in the charge reservoir-in contrast to results from all-electrical transport measurements. Using a master equation approach, which includes both the electron tunneling and the optical excitation or recombination, we are able to explain the experimental data by optical blocking, which also reduces the electron tunneling rate when the QD is occupied by an exciton.

Comorbidity indices for clinical trials: adaptation of two existing indices for use with the FREEDOM trial in women with postmenopausal osteoporosis

Two comorbidity indices were adapted for use in the FREEDOM trial and significantly correlated with the number of medications and impaired health status at baseline. The indices have applications for the analysis of clinical trial data and would allow for the appropriate adjustment of comorbidities when evaluating clinical trial outcomes.

INTRODUCTION

The purpose of this study is to adapt two published comorbidity indices for use with the FREEDOM clinical trial evaluating postmenopausal women with osteoporosis.

METHODS

FREEDOM enrolled women aged 60-90 years with a bone mineral density T-score <-2.5 at the lumbar spine or total hip and ≥-4.0 at both sites. Comorbidity indices were calculated using methods described by Sangha (Arthritis Rheum 49:156-163, 2003) and Wolfe (J Rheumatol 37:305-315, 2010) following modification. The adapted Sangha index included 12 conditions with a summary score of 0-12; the adapted Wolfe index included 7 conditions with a weighted summary score of 0-8. Higher scores indicated greater comorbidity. A panel of clinicians independently reviewed subjects' medical histories using a systematic process based on Medical Dictionary for Regulatory Activities (MedDRA) preferred terms to map specified comorbid conditions. Spearman correlations between the adapted indices and baseline subject characteristics expected to be associated with comorbidities were examined.

RESULTS

Of the 7808 subjects in this study, 74 % had ≥1 comorbidities based on the adapted Sangha or Wolfe comorbidity indices. The mean (SD) adapted Sangha and Wolfe comorbidity indices were 1.4 (1.2) and 1.4 (1.3), respectively. Both indices correlated positively with age, body mass index, and the number of medications (r = 0.54 to 0.55) at baseline and inversely correlated with health-related quality of life (r = -0.22 to -0.30) (all P < 0.0001). Further, when either the adapted Sangha or Wolfe index was included as a covariate for assessing mortality over 36 months in the FREEDOM population, the hazard ratio of the comorbidity index indicated that the mortality risk increased by 27 or 28 %, respectively, for each unit increase in the adapted index (both P < 0.0001).

CONCLUSIONS

Our work suggests these comorbidity indices may be adapted for use with clinical trial data, thereby allowing for the appropriate adjustment and reporting of covariates in the evaluation of clinical trial outcomes in an osteoporotic population.

Low-level red laser therapy alters effects of ultraviolet C radiation on Escherichia coli cells

Low-level lasers are used at low power densities and doses according to clinical protocols supplied with laser devices or based on professional practice. Although use of these lasers is increasing in many countries, the molecular mechanisms involved in effects of low-level lasers, mainly on DNA, are controversial. In this study, we evaluated the effects of low-level red lasers on survival, filamentation, and morphology of Escherichia colicells that were exposed to ultraviolet C (UVC) radiation. Exponential and stationary wild-type and uvrA-deficientE. coli cells were exposed to a low-level red laser and in sequence to UVC radiation. Bacterial survival was evaluated to determine the laser protection factor (ratio between the number of viable cells after exposure to the red laser and UVC and the number of viable cells after exposure to UVC). Bacterial filaments were counted to obtain the percentage of filamentation. Area-perimeter ratios were calculated for evaluation of cellular morphology. Experiments were carried out in duplicate and the results are reported as the means of three independent assays. Pre-exposure to a red laser protected wild-type and uvrA-deficient E. coli cells against the lethal effect of UVC radiation, and increased the percentage of filamentation and the area-perimeter ratio, depending on UVC fluence and physiological conditions in the cells. Therapeutic, low-level red laser radiation can induce DNA lesions at a sub-lethal level. Consequences to cells and tissues should be considered when clinical protocols based on this laser are carried out.

Dietetic management in gastrointestinal complications from antimalignant chemotherapy

Antineoplastic chemotherapy (CT) represents the systemic treatment of malignant tumors. It can be used alone or combined with surgery and / or radiotherapy. The cytotoxic agents used in chemotherapy work on both cancerous cells and noncancerous cells of the body, generally resulting in high toxicity. The biological aggressiveness of chemotherapy particularly affects rapidly replicating cells, such as those of the digestive tract, resulting in adverse effects that impair food intake, leading to compromised nutritional status and which may lead to cachexia. The main toxic effects of chemotherapy in the gastrointestinal tract include nausea, vomiting -these are the most frequent- constipation, diarrhea, xerostomia, mucositis, dysphagia and anorexia. Given the high frequency of such effects, nutritional intervention should be an integral part of cancer treatment, to maintain and/or improve the patient's nutritional status and reduce or minimize the side effects caused by treatment. Accordingly, the goal of this study is to review dietetic conduct in the process of caring for patients undergoing cancer chemotherapy.

International consensus on (ICON) pediatric asthma

Asthma is the most common chronic lower respiratory disease in childhood throughout the world. Several guidelines and/or consensus documents are available to support medical decisions on pediatric asthma. Although there is no doubt that the use of common systematic approaches for management can considerably improve outcomes, dissemination and implementation of these are still major challenges. Consequently, the International Collaboration in Asthma, Allergy and Immunology (iCAALL), recently formed by the EAACI, AAAAI, ACAAI, and WAO, has decided to propose an International Consensus on (ICON) Pediatric Asthma. The purpose of this document is to highlight the key messages that are common to many of the existing guidelines, while critically reviewing and commenting on any differences, thus providing a concise reference. The principles of pediatric asthma management are generally accepted. Overall, the treatment goal is disease control. To achieve this, patients and their parents should be educated to optimally manage the disease, in collaboration with healthcare professionals. Identification and avoidance of triggers is also of significant importance. Assessment and monitoring should be performed regularly to re-evaluate and fine-tune treatment. Pharmacotherapy is the cornerstone of treatment. The optimal use of medication can, in most cases, help patients control symptoms and reduce the risk for future morbidity. The management of exacerbations is a major consideration, independent of chronic treatment. There is a trend toward considering phenotype-specific treatment choices; however, this goal has not yet been achieved.

Optical properties of heavily doped GaAs nanowires and electroluminescent nanowire structures

We present GaAs electroluminescent nanowire structures fabricated by metal organic vapor phase epitaxy. Electroluminescent structures were realized in both axial pn-junctions in single GaAs nanowires and free-standing nanowire arrays with a pn-junction formed between nanowires and substrate, respectively. The electroluminescence emission peak from single nanowire pn-junctions at 10 K was registered at an energy of around 1.32 eV and shifted to 1.4 eV with an increasing current. The line is attributed to the recombination in the compensated region present in the nanowire due to the memory effect of the vapor-liquid-solid growth mechanism. Arrayed nanowire electroluminescent structures with a pn-junction formed between nanowires and substrate demonstrated at 5 K a strong electroluminescence peak at 1.488 eV and two shoulder peaks at 1.455 and 1.519 eV. The main emission line was attributed to the recombination in the p-doped GaAs. The other two lines correspond to the tunneling-assisted photon emission and band-edge recombination in the abrupt junction, respectively. Electroluminescence spectra are compared with the micro-photoluminescence spectra taken along the single p-, n- and single nanowire pn-junctions to find the origin of the electroluminescence peaks, the distribution of doping species and the sharpness of the junctions.

XeF(2) gas-assisted focused-electron-beam-induced etching of GaAs with 30 nm resolution

We demonstrate the gas-assisted focused-electron-beam (FEB)-induced etching of GaAs with a resolution of 30 nm at room temperature. We use a scanning electron microscope (SEM) in a dual beam focused ion beam together with xenon difluoride (XeF(2)) that can be injected by a needle directly onto the sample surface. We show that the FEB-induced etching with XeF(2) as a precursor gas results in isotropic and smooth etching of GaAs, while the etch rate depends strongly on the beam current and the electron energy. The natural oxide of GaAs at the sample surface inhibits the etching process; hence, oxide removal in combination with chemical surface passivation is necessary as a strategy to enable this high-resolution etching alternative for GaAs.

Diclofenac plus B vitamins versus diclofenac monotherapy in lumbago: the DOLOR study

OBJECTIVES

To assess the influence of vitamins B1, B6 and B12 on the analgesia success achieved by diclofenac in subjects with acute lumbago.

RESEARCH DESIGN AND METHODS

A randomised, double blind controlled clinical study in parallel groups, in which subjects received twice-daily oral administration of either the combination therapy, Group DB (50 mg diclofenac plus 50 mg thiamine, 50 mg pyridoxine and 1 mg cyanocobalamin) or diclofenac monotherapy, Group D (50mg diclofenac). The study period lasted a maximum of 7 days. If sufficient pain reduction was achieved (defined as Visual Analogue Scale <20 mm and patient's satisfaction), subjects could withdraw from the treatment after 3 or 5 days. All subjects gave written informed consent to participate in the study.

MAIN OUTCOME MEASURES

The primary confirmatory study objective was to determine the number of patients with sufficient pain reduction after 3 days of treatment.

RESULTS

Three hundred and seventy-two subjects were allocated at random to either treatment group: Group DB - 187 subjects and Group D - 185 subjects. After 3 days of treatment, a statistically significant higher proportion of subjects in Group DB (n = 87; 46.5%) than in Group D (n = 55; 29%) terminated the study due to treatment success (chi(2): 12.06; p = 0.0005). Furthermore, the combination therapy yielded superior results in pain reduction, improvement of mobility and functionality. Drug safety monitoring profile throughout the trial was within the expected safety profile of diclofenac.

CONCLUSIONS

The combination of diclofenac with B vitamins was superior to diclofenac monotherapy in lumbago relief after 3 days of treatment. As a study drawback, daily VAS measurements were only recorded until subject withdrawal from treatment, whether after 3, 5, or 7 days. There were no differences in safety profile between the two study groups.

Validation of tissue microarray technology in malignant peripheral nerve sheath tumours

BACKGROUND

It has been suggested that the donor tissue cores used in tissue microarrays (TMAs) may not be representative of the whole tissue section.

AIM

To validate the use of TMA technology in the study of malignant peripheral nerve sheath tumours (MPNSTs).

METHODS

A TMA was constructed containing five independent core biopsy samples of 14 formalin-fixed, paraffin-embedded MPNSTs. The immunohistochemical (IHC) results of the five cores from the same tissue block on TMA were compared with readings from whole sections using two antibodies: anti-Ki-67 and anti-S-100. Digital image analysis was performed to calculate the percentage of positive stain areas. The agreement between IHC results obtained with TMA cores and whole sections was assessed using the kappa statistic.

RESULTS

There was good to very good agreement between IHC results for whole and TMA sections from MPNSTs. In relation to S-100, very good agreement (92% agreement; kappa = 0.77) was observed using a minimum of four TMA cores. Staining results for Ki-67 from at least four readable TMA cores were the same as those for the whole section in 86% of cases, with good agreement, using weighted kappa statistics (kappa = 0.63).

CONCLUSIONS

This study indicates that the TMA technique can be used in the IHC study of MPNSTs, even with the use of heterogeneous markers such as S-100 protein.

Serum IgE levels in neurofibromatosis 1

A descriptive case study was performed on 75 patients with NF1 (neurofibromatosis type 1) from the CNNF (Brazil) database. Serum IgE levels were determined using the IgE radioimmunosorbent test, with the reference values of 75-502 IU mL(-1). The patients were divided into groups, with 25 patients presenting plexiform neurofibromas, 25 presenting neurofibromas and 25 presenting no neurofibromas. The purposes of this study were to determine the serum IgE levels of patients with NF1 presenting plexiform neurofibromas, neurofibromas and no neurofibromas, as well as to determine possible correlations between serum IgE levels and the size of the plexiform neurofibromas and neurofibromas presented by these patients. Elevated serum IgE levels were observed in all the patient groups. We did not observe a correlation between IgE levels and age in these patients; however, we did observe correlations between IgE levels and neurofibroma and plexiform neurofibroma size. We suggest further studies to confirm these results and to investigate in greater depth the possible role of IgE in the development and growth of neurofibromas and plexiform neurofibromas in NF1.

Angiogenesis in normal and neoplastic ovaries

Ovarian physiology is intricately connected to hormonally regulated angiogenic response. Recent advances in the post genomic revolution have significantly impacted our understanding of ovarian function. In an angiogenesis perspective, the ovary offers a unique opportunity to unravel the molecular orchestration of blood vessel development and regression under normal conditions. A majority of ovarian cancers develop from the single layer of epithelium surrounding the ovaries. Angiogenesis is critical for the development of ovarian cancer and its peritoneal dissemination. The present review summarizes recent findings on the angiogenic response in neoplastic ovaries and discusses the prospects of using anti-angiogenic approaches to treat ovarian cancer.

[Treatment with enoxaparin adapted to the fertility programs in women with recurrent abortion and thrombophilia]

Acquired and inherited thrombophilia are associated with recurrent pregnancy loss (RPL). Antithrombotic therapy could restore hemostatic balance and improve early placentation and gestational outcome. We evaluated the efficacy of enoxaparin adapted to the fertility program for prevention of pregnancy loss in 35 women (W) with early RPL and thrombophilia. Previous to the diagnosis of thrombophilia, they had had a total of 105 gestations of which 89 (85%) ended in early pregnancy loss. After diagnosis of thrombophilia, 35 subsequent pregnancies were treated with enoxaparin. In 5 cases assisted reproductive techniques were necessary to achieve pregnancy due to couple infertility. In 17 W who had had at least one preclinical pregnancy loss, enoxaparin (20 mg/d/s.c.) was started previous to conception and adapted to the fertility program. All the women continued with the gestational regime. Eighteen W with only clinical pregnancy loss started enoxaparin (20 mg twice per day s.c.) after biochemical pregnancy diagnosis. During gestations heparin dose was adjusted with anti Xa test, maintaining a range between 0.3 at 0.6 u/ml. With antithrombotic therapy, 30/35 (85%) of the pregnancies ended in live birth versus 16/105 (15%) of the pregnancies without treatment (p < 0.001). These results suggest that enoxaparin adapted to the fertility program can be effective in the prevention of preclinical and clinical abortion in women with thrombophilia.

Efficacy and safety of moricizine in the maintenance of sinus rhythm in patients with recurrent atrial fibrillation

Maintenance of sinus rhythm is the primary goal of antiarrhythmic drug therapy for recurrent atrial fibrillation (AF). However, concern about proarrhythmic and negative inotropic effects has led to increasing reluctance to administer antiarrhythmic agents for this non-life-threatening arrhythmia. Moricizine is well tolerated in a wide variety of patients, and therefore, may be a safe and effective agent for treating AF. We retrospectively assessed the efficacy and safety of moricizine (mean dose 609 +/- 9 mg/day) in 85 consecutive patients with recurrent AF (2.6 +/- 0.5 years duration, 1.6 +/- 1 failed antiarrhythmic drugs). Structural heart disease was present in 69 (81%), but no recent myocardial infarct (< or =90 days) was present; mean left atrial size was 46 +/- 1 mm, and mean left ventricular ejection fraction was 0.51 +/- 0.01. Moricizine was discontinued because of unsuccessful direct-current cardioversion (n = 5) or clinically unacceptable side effects (n = 6); 6 patients developed transient side effects not requiring discontinuation. Of the 74 patients continuing therapy, 68% remained in sinus rhythm after 6 months, and 59% after 12 months. During a follow-up (21 +/- 2 months), there were neither deaths nor adverse effects requiring discontinuation of therapy. Thus, moricizine was effective, safe, and well tolerated in our patient cohort with AF.

Ligand design package (Ludi--MSI) applied to known inhibitors of the HIV-1 protease. Test of performance

Performance of the Ludi (Insight II--MSI, ver. 98.0) program for computer-aided Ligand Design was tested using four crystallographic complexes of inhibitors with the HIV-1 protease. Possibility of reconstruction of the side chains and the peptide bond of the inhibitors, as well as attempt to construct de novo the central parts of these inhibitors, starting from the native structure of the enzyme, was studied. Results points that Ludi, although helpful, is merely initial tool for computer aided drug design. Moreover, some improvement of the program code is needed.

End-of-life care in the pediatric intensive care unit after the forgoing of life-sustaining treatment

OBJECTIVE

To describe the attitudes and practice of clinicians in providing sedation and analgesia to dying patients as life-sustaining treatment is withdrawn.

STUDY DESIGN

Prospective case series of 53 consecutive patients who died after the withdrawal of life-sustaining treatment in the pediatric intensive care unit at three teaching hospitals in Boston. Data on the reasons why medications were given were obtained from a self-administered anonymous questionnaire completed by the critical care physician and nurse for each case. Data on what medications were given were obtained from a review of the medical record.

RESULTS

Sedatives and/or analgesics were administered to 47 (89%) patients who died after the withdrawal of life-sustaining treatment. Patients who were comatose were less likely to receive these medications. Physicians and nurses cited treatment of pain, anxiety, and air hunger as the most common reasons, and hastening death as the least common reason, for administration of these medications. Hastening death was viewed as an "acceptable, unintended side effect" of terminal care by 91% of physician-nurse matched pairs. The mean dose of sedatives and analgesics administered nearly doubled as life-support was withdrawn, and the degree of escalation in dose did not correlate with clinician's views on hastening death.

CONCLUSION

Clinicians frequently escalate the dose of sedatives or analgesics to dying patients as life-sustaining treatment is withdrawn, citing patient-centered reasons as their principle justification. Hastening death is seen as an unintended consequence of appropriate care. A large majority of physicians and nurses agreed with patient management and were satisfied with the care provided. Care of the dying patient after the forgoing of life-sustaining treatment remains underanalyzed and needs more rigorous examination by the critical care community.

Thermodynamic linkage between the binding of protons and inhibitors to HIV-1 protease

The aspartyl dyad of free HIV-1 protease has apparent pK(a)s of approximately 3 and approximately 6, but recent NMR studies indicate that the aspartyl dyad is fixed in the doubly protonated form over a wide pH range when cyclic urea inhibitors are bound, and in the monoprotonated form when the inhibitor KNI-272 is bound. We present computations and measurements related to these changes in protonation and to the thermodynamic linkage between protonation and inhibition. The Poisson-Boltzmann model of electrostatics is used to compute the apparent pK(a)s of the aspartyl dyad in the free enzyme and in complexes with four different inhibitors. The calculations are done with two parameter sets. One assigns epsilon = 4 to the solute interior and uses a detailed model of ionization; the other uses epsilon = 20 for the solute interior and a simplified representation of ionization. For the free enzyme, both parameter sets agree well with previously measured apparent pK(a)s of approximately 3 and approximately 6. However, the calculations with an internal dielectric constant of 4 reproduce the large pKa shifts upon binding of inhibitors, but the calculations with an internal dielectric constant of 20 do not. This observation has implications for the accurate calculation of pK(a)s in complex protein environments. Because binding of a cyclic urea inhibitor shifts the pK(a)s of the aspartyl dyad, changing the pH is expected to change its apparent binding affinity. However, we find experimentally that the affinity is independent of pH from 5.5 to 7.0. Possible explanations for this discrepancy are discussed.

Expression of 15-lipoxygenase by human colorectal carcinoma Caco-2 cells during apoptosis and cell differentiation

We studied arachidonic acid metabolism and the expression of cyclooxygenase (Cox) and 15-lipoxygenase (15-LO) in the human colorectal carcinoma cell line, Caco-2, which undergo apoptosis and cell differentiation in the presence of sodium butyrate (NaBT). Caco-2 cells expressed very low levels of Cox-1 but highly expressed Cox-2. NaBT treatment shifted the arachidonic acid metabolites by cell lysates from prostaglandins to 15-hydroxyeicosatetraenoic acid, indicating the presence of a 15-LO. Linoleic acid, an excellent substrate for 15-LO, was metabolized poorly by the Caco-2 cells, but NaBT treatment shifted metabolism to 15-LO metabolite, 13(S)-hydroxyoctadecadienoic acid. Caco-2 cells expressed a 15-LO but only after treatment with NaBT, as determined by Northern blotting. Immunoblotting with anti-human 15-LO antibody detected a 72-kDa band in NaBT-treated Caco-2 cells. Expression of 15-LO mRNA was dependent on the duration of NaBT treatment, with the highest expression observed between 10 and 24 h. Results from expression and metabolism studies with arachidonic and linoleic acid cells indicated Cox-2 was responsible for the lipid metabolism in control cells, whereas 15-LO was the major enzyme responsible after NaBT induction of apoptosis and cell differentiation. The 15-LO in Caco-2 cells was characterized as human reticulocyte 15-LO by reverse transcription-polymerase chain reaction and restriction enzyme analysis. The expression of 15-LO and 15-hydroxyeicosatetraenoic acid or 13(S)-hydroxyoctadecadienoic acid formation correlates with cell differentiation or apoptosis in Caco-2 cells induced by NaBT. The addition of nordihydroguaiaretic acid, a lipoxygenase inhibitor, significantly increased NaBT-induced apoptosis, whereas the addition of indomethacin did not alter NaBT-induced apoptosis in the Caco-2 cells. However, indomethacin treatment decreased the expression of Cox-2 in NaBT-treated cells and significantly increased the expression of 15-LO during NaBT treatment. These studies suggest a role for 15-LO, in addition to Cox-2, in modulating NaBT-induced apoptosis and cell differentiation in human colorectal carcinoma cells.