Studies with positive results are greatly more represented in literature than studies with negative results, producing so-called publication bias. This review aims to discuss occurring problems around negative results and to emphasize the importance of reporting negative results. Underreporting of negative results introduces bias into meta-analysis, which consequently misinforms researchers, doctors and policymakers. More resources are potentially wasted on already disputed research that remains unpublished and therefore unavailable to the scientific community. Ethical obligations need to be considered when reporting results of studies on human subjects as people have exposed themselves to risk with the assurance that the study is performed to benefit others. Some studies disprove the common conception that journal editors preferably publish positive findings, which are considered as more citable. Therefore, all stakeholders, but especially researchers, need to be conscious of disseminating negative and positive findings alike.

Informed consent is a process in which a human subject who is to participate in research needs to give his or her consent after being properly informed of the expected benefits as well as the potential harm of the research that will be performed. The function and purpose of the research ethics committee is to ensure that the research that will take place is in accordance with the relevant ethical standards. This means that the committee must assess the appropriateness of the design of the study reviewed. Research in the field of laboratory medicine has specific features, i.e. the use of samples that remain after routine analysis, data collection from databases containing patient information, data mining, collection of laboratory management data, method/instrument comparisons and validation, etc. As most of such research is either retrospective or not directly associated with patients, the question arises as to whether all types of research require informed consent and ethics committee approval. This article aims to clarify what is specific about obtaining informed consent and ethical approval in laboratory medicine, to provide general guidance on informed consent and ethical approval requirements based on the type of study, and what information should be included in applications for ethical approval and informed consent. This could also provide some guidance for future contributors to the Biochemia Medica.

The nephrotoxic mycotoxin ochratoxin A (OTA), a common contaminant of cereals, has been implicated in the etiology of endemic nephropathy. It was also frequently found in low concentrations in blood of healthy populations in countries where endemic nephropathy is not known. However, data on regional and seasonal differences in the frequency and concentration of OTA in human blood are scarce. In June, September and December 1997, and March 1998, about 50 human blood samples were collected randomly from blood donors for blood banks in the Coatian cities of Osijek, Rijeka, Split, VaraZdin and Zagreb. OTA was measured in the total of 983 samples using an HPLC technique with fluorescent detection. The daily intake of OTA was estimated from the mean concentration found in different cities and at different times of year. Samples containing OTA above the detection limit (0.2 ng/ml of plasma) were found in populations from all Croatian cities at all collecting periods. The highest frequency (59%) of samples containing OTA above the detection limit and the highest mean concentration (0.39 ng/ml) were found in June. Both the frequency and the mean concentration were lowest in all samples in December (36% and 0.19 ng OTA/ml, respectively). Osijek was the city with the highest frequency of OTA-positive samples (81%) and the highest mean OTA concentration (0.56 ng/ml). The total mean concentration of OTA in blood of healthy population in Croatia is lower (0.30 ng/ ml) than the mean concentration in European countries as a whole (0.90 ng/ml). The estimated daily intake, calculated from the mean concentration in all blood samples, is 0.40 ng OTA/kg body weight, which is much lower than that proposed by World Health Organization as the tolerable daily intake (16.0 ng/kg body weight). Healthy populations of Croatia are exposed to low, but seasonally and regionally variable amounts of OTA.

IntroductionOur aim was to investigate if: (a) authors of Biochemia Medica meet authorship criteria given by International Committee of Medical Journal Editors (ICMJE), (b) authorship violations are more frequent in submissions containing some type of scientific misconduct.Materials and methodsSelf-reported authorship contributions regarding the three ICMJE criteria were analysed for all submissions to Biochemia Medica (February 2013-April 2015) which were forwarded to peer-review. To test the differences in frequencies we used Chi-squared test. P < 0.05 was considered statistically significant.Results186 manuscripts were authored by 804 authors. All ICMJE criteria were met by 487/804 (61%) authors. The first and the last author met all the criteria more frequently than those authors in between (P < 0.001). The degree to which ICMJE criteria was met for the first author did not differ between manuscripts authored by only one author and those authored by >1 author (P = 0.859). In 9% of the manuscripts ICMJE criteria were not met by a single author. Authors of the 171/186 manuscripts declared that all persons qualify for authorship but only 49% of them satisfied all ICMJE criteria. Authors have failed to acknowledge contributors in 88/186 (47%) manuscripts; instead these contributors have been listed as authors without fulfilling ICMJE criteria. Authorship violation was not more common in 42 manuscripts with some type of scientific misconduct (P = 0.135).ConclusionLarge proportion of authors of the manuscripts submitted to Biochemia Medica do not fulfil ICMJE criteria. Violation of authorship criteria is not more common for manuscripts with some type of scientific misconduct.

Instructions for authors (IFA) need to be informative and regularly updated. We hypothesized that journals with a higher impact factor (IF) have more comprehensive IFA. The aim of the study was to examine whether IFA of journals indexed in the Journal Citation Reports 2013, "Medical Laboratory Technology" category, are written in accordance with the latest recommendations and whether the quality of instructions correlates with the journals' IF. 6 out of 31 journals indexed in "Medical Laboratory Technology" category were excluded (unsuitable or unavailable instructions). The remaining 25 journals were scored based on a set of 41 yes/no questions (score 1/0) and divided into four groups (editorial policy, research ethics, research integrity, manuscript preparation) by three authors independently (max score = 41). We tested the correlation between IF and total score and the difference between scores in separate question groups. The median total score was 26 (21-30) [portion of positive answers 0.63 (0.51-0.73)]. There was no statistically significant correlation between a journal's IF and the total score (rho = 0.291, P = 0.159). IFA included recommendations concerning research ethics and manuscript preparation more extensively than recommendations concerning editorial policy and research integrity (Ht = 15.91, P = 0.003). Some policies were poorly described (portion of positive answers), for example: procedure for author's appeal (0.04), editorial submissions (0.08), appointed body for research integrity issues (0.08). The IF of the "Medical Laboratory Technology" journals does not reflect a journals' compliance to uniform standards. There is a need for improving editorial policies and the policies on research integrity.