Identification of Fungal Limonene-3-Hydroxylase for Biotechnological Menthol Production.

More than 30,000 tons of menthol are produced every year as a flavor and fragrance compound or as a medical component. So far, only extraction from plant material and chemical synthesis are possible. An alternative approach for menthol production could be a biotechnological-chemical process with ideally only two conversion steps, starting from (+)-limonene, which is a side product of the citrus processing industry. The first step requires a limonene-3-hydroxylase (L3H) activity that specifically catalyzes hydroxylation of limonene at carbon atom 3. Several protein engineering strategies have already attempted to create limonene-3-hydroxylases from bacterial cytochrome P450 monooxygenases (CYPs, or P450s), which can be efficiently expressed in bacterial hosts. However, their regiospecificity is rather low compared to that of the highly selective L3H enzymes from the biosynthetic pathway for menthol in Mentha species. The only naturally occurring limonene-3-hydroxylase activity identified in microorganisms so far was reported for a strain of the black yeast-like fungus Hormonema sp. in South Africa. We have discovered additional fungi that can catalyze the intended reaction and identified potential CYP-encoding genes within the genome sequence of one of the strains. Using heterologous gene expression and biotransformation experiments in yeasts, we were able to identify limonene-3-hydroxylases from Aureobasidium pullulans and Hormonema carpetanum Further characterization of the A. pullulans enzyme demonstrated its high stereospecificity and regioselectivity, its potential for limonene-based menthol production, and its additional ability to convert α- and ß-pinene to verbenol and pinocarveol, respectively.IMPORTANCE (-)-Menthol is an important flavor and fragrance compound and furthermore has medicinal uses. To realize a two-step synthesis starting from renewable (+)-limonene, a regioselective limonene-3-hydroxylase enzyme is necessary. We identified enzymes from two different fungi which catalyze this hydroxylation reaction and represent an important module for the development of a biotechnological process for (-)-menthol production from renewable (+)-limonene.

Late decisions about treatment limitation in patients with cancer: empirical analysis of end-of-life practices in a haematology and oncology unit at a German university hospital.

BACKGROUND: Decisions to limit treatment (DLTs) are important to protect patients from overtreatment but constitute one of the most ethically challenging situations in oncology practice. In the Ethics Policy for Advance Care Planning and Limiting Treatment study (EPAL), we examined how often DLT preceded a patient's death and how early they were determined before (T1) and after (T2) the implementation of an intrainstitutional ethics policy on DLT. METHODS: This prospective quantitative study recruited 1.134 patients with haematological/oncological neoplasia in a period of 2×6 months at the University Hospital of Munich, Germany. Information on admissions, discharges, diagnosis, age, DLT, date and place of death, and time span between the initial determination of a DLT and the death of a patient was recorded using a standardised form. RESULTS: Overall, for 21% (n=236) of the 1.134 patients, a DLT was made. After implementation of the policy, the proportion decreased (26% T1/16% T2). However, the decisions were more comprehensive, including more often the combination of 'Do not resuscitate' and 'no intense care unit' (44% T1/64% T2). The median time between the determination of a DLT and the patient's death was similarly short with 6 days at a regular ward (each T1/T2) and 10.5/9 (T1/T2) days at a palliative care unit. For patients with solid tumours, the DLTs were made earlier at both regular and palliative care units than for the deceased with haematological neoplasia. CONCLUSION: Our results show that an ethics policy on DLT could sensitise for treatment limitations in terms of frequency and extension but had no significant impact on timing of DLT. Since patients with haematological malignancies tend to undergo intensive therapy more often during their last days than patients with solid tumours, special attention needs to be paid to this group. To support timely discussions, we recommend the concept of advance care planning.

High prevalence of moral distress reported by oncologists and oncology nurses in end-of-life decision making.

OBJECTIVE: Decisions to limit life-prolonging treatment (DLT) are often accompanied by psychological and ethical difficulties. The aim of the study is to investigate prevalence and intensity of moral distress (MD) as well as potential causes experienced by oncology physicians and nurses in DLT situations. METHODS: This prospective study at a German university hospital included n = 100 advanced cancer inpatients with DLT. We surveyed their respective physicians and nurses to assess MD in DLT using an adapted distress thermometer and an open-ended question to specify reasons of MD. We also collected data on the decision-making process from the perspective of the clinicians. RESULTS: Physicians report MD in 67% (n = 51) and nurses in 74% (n = 67) of the cases. The MD level in nurses (mean 2.3; SD 2.3) is significantly higher (P = .005) than in physicians (mean 1.5; SD 1.4). Uncertainties concerning ethical aspects in DLT in a patient case are associated with MD in both physicians (P = .024) and nurses (P = .004). Involvement of nurses in DLT is the strongest predictor (P = .000) for MD as indicated by physicians. Nurses experience MD especially, if the patient has a low quality of life (P = .001). CONCLUSIONS: Moral distress is experienced by both oncologists and nurses in DLT. Nurses report higher MD intensity compared with physicians although the ultimate responsibility for DLT lies with the physicians. Support for the challenging decisions may be provided through the implementation of an ethical guideline and enhanced interprofessional communication.

Development and Evaluation of an Ethical Guideline for Decisions to Limit Life-Prolonging Treatment in Advanced Cancer: Protocol for a Monocentric Mixed-Method Interventional Study.

BACKGROUND: Many patients with advanced cancer receive chemotherapy close to death and are referred too late to palliative or hospice care, and therefore die under therapy or in intensive care units. Oncologists still have difficulties in involving patients appropriately in decisions about limiting tumor-specific or life-prolonging treatment. OBJECTIVE: The aim of this Ethics Policy for Advanced Care Planning and Limiting Treatment Study is to develop an ethical guideline for end-of-life decisions and to evaluate the impact of this guideline on clinical practice regarding the following target goals: reduction of decisional conflicts, improvement of documentation transparency and traceability, reduction of distress of the caregiver team, and better knowledge and consideration of patients' preferences. METHODS: This is a protocol for a pre-post interventional study that analyzes the clinical practice on treatment limitation before and after the guideline implementation. An embedded researcher design with a mixed-method approach encompassing both qualitative and quantitative methods is used. The study consists of three stages: (1) the preinterventional phase, (2) the intervention (development and implementation of the guideline), and 3) the postinterventional phase (evaluation of the guideline's impact on clinical practice). We evaluate the process of decision-making related to limiting treatment from different perspectives of oncologists, nurses, and patients; comparing them to each other will allow us to develop the guideline based on the interests of all parties. RESULTS: The first preintervention data of the project have already been published, which detailed a qualitative study with oncologists and oncology nurses (n=29), where different approaches to initiation of end-of-life discussions were ethically weighted. A framework for oncologists was elaborated, and the study favored an anticipatory approach of preparing patients for forgoing therapy throughout the course of disease. Another preimplementational study of current decision-making practice (n=567 patients documented) demonstrated that decisions to limit treatment preceded the death of many cancer patients (62/76, 82% of deceased patients). However, such decisions were usually made in the last week of life, which was relatively late. CONCLUSIONS: The intervention will be evaluated with respect to the following endpoints: better knowledge and consideration of patients' treatment wishes; reduction of decisional conflicts; improvement of documentation transparency and traceability; and reduction of the psychological and moral distress of a caregiver team. REGISTERED REPORT IDENTIFIER: RR1-10.2196/9698.