Advancements in the gold standard: Measuring steroid sex hormones by mass spectrometry.

Sex hormones, such as testosterone and estrogens, play an essential role in regulating physiological and reproductive development throughout the lifetime of the individual. Although variation in levels of these hormones are observed throughout the distinct stages in life, significant deviations from reference ranges can result in detrimental effects to the individual. Alterations, by either an increase or decrease, in hormone levels are associated with physiological changes, decreased reproductive capabilities, and increased risk for diseases. Hormone therapies (HTs) and assisted reproductive technologies (ARTs) are commonly used to address these factors. In addition to these treatments, gender-affirming therapies, an iteration of HTs, are also a prominent treatment for transgender individuals. Considering that the effectiveness of these treatments relies on achieving therapeutic hormone levels, monitoring of hormones has served as a way of assessing therapeutic efficay. The need for reliable methods to achieve this task has led to great advancements in methods for evaluating hormone concentrations in biological matrices. Although immunoassays are the more widely used method, mass spectrometry (MS)-based methods have proven to be more sensitive, specific, and reliable. Advances in MS technology and its applications for therapeutic hormone monitoring have been significant, hence integration of these methods in the clinical setting is desired. Here, we provide a general overview of HT and ART, and the immunoassay and MS-based methods currently utilized for monitoring sex hormones. Additionally, we highlight recent advances in MS-based methods and discuss future applications and considerations for MS-based hormone assays.

Recent Developments of Useful MALDI Matrices for the Mass Spectrometric Characterization of Lipids.

Matrix-assisted laser desorption/ionization (MALDI) is one of the most successful "soft" ionization methods in the field of mass spectrometry and enables the analysis of a broad range of molecules, including lipids. Although the details of the ionization process are still unknown, the importance of the matrix is commonly accepted. Both, the development of and the search for useful matrices was, and still is, an empirical process, since properties like vacuum stability, high absorption at the laser wavelength, etc. have to be fulfilled by a compound to become a useful matrix. This review provides a survey of successfully used MALDI matrices for the lipid analyses of complex biological samples. The advantages and drawbacks of the established organic matrix molecules (cinnamic or benzoic acid derivatives), liquid crystalline matrices, and mixtures of common matrices will be discussed. Furthermore, we will deal with nanocrystalline matrices, which are most suitable to analyze small molecules, such as free fatty acids. It will be shown that the analysis of mixtures and the quantitative analysis of small molecules can be easily performed if the matrix is carefully selected. Finally, some basic principles of how useful matrix compounds can be "designed" de novo will be introduced.

Assessing the potential of sputtered gold nanolayers in mass spectrometry imaging for metabolomics applications.

Mass spectrometry imaging (MSI) is a molecular imaging technique that maps the distribution of molecules in biological tissues with high spatial resolution. The most widely used MSI modality is matrix-assisted laser desorption/ionization (MALDI), mainly due to the large variety of analyte classes amenable for MALDI analysis. However, the organic matrices used in classical MALDI may impact the quality of the molecular images due to limited lateral resolution and strong background noise in the low mass range, hindering its use in metabolomics. Here we present a matrix-free laser desorption/ionization (LDI) technique based on the deposition of gold nanolayers on tissue sections by means of sputter-coating. This gold coating method is quick, fully automated, reproducible, and allows growing highly controlled gold nanolayers, necessary for high quality and high resolution MS image acquisition. The performance of the developed method has been tested through the acquisition of MS images of brain tissues. The obtained spectra showed a high number of MS peaks in the low mass region (m/z below 1000 Da) with few background peaks, demonstrating the ability of the sputtered gold nanolayers of promoting the desorption/ionization of a wide range of metabolites. These results, together with the reliable MS spectrum calibration using gold peaks, make the developed method a valuable alternative for MSI applications.

MALDI-TOF MS in the Microbiology Laboratory: Current Trends.

Within less than a decade matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has become a gold standard for microbial identification in clinical microbiology laboratories. Besides identification of microorganisms the typing of single strains as well as the antibiotic and antimycotic resistance testing has come into focus in order to speed up the microbiological diagnostic. However, the full potential of MALDI-TOF MS has not been tapped yet and future technological advancements will certainly expedite this method towards novel applications and enhancement of current practice. So, the following chapter shall be rather a brainstorming and forecast of how MALDI-TOF MS will develop to influence clinical diagnostics and microbial research in the future. It shall open up the stage for further discussions and does not claim for overall validity.

[New microbiological techniques]. / Neue mikrobiologische Techniken.

Microbiological diagnostic procedures have changed rapidly in recent years. This is especially true in the field of molecular diagnostics. Classical culture-based techniques are still the gold standard in many areas; however, they are already complemented by automated and also molecular techniques to guarantee faster and better quality results. The most commonly used techniques include real-time polymerase chain reaction (RT-PCR) based systems and nucleic acid hybridization. These procedures are used most powerfully from direct patient samples or in assays to detect the presence of nonculturable or fastidious organisms. Further techniques such as DNA sequencing are not yet used routinely for urological samples and can be considered experimental. However, in conjunction with dropping prices and further technical developments, these techniques promise to be used much more in the near future. Regarding bacterial identification from culture, mass spectrometry (MALDI-TOF MS) has become the technique of choice in recent years especially in Europe. It has tremendously shortened the time to result. This is now going to be extended to antibiotic susceptibility testing. This is of paramount importance in view of ever rising antimicrobial resistance rates. Techniques described in this review offer a faster and better microbiological diagnosis. Such continuous improvements are critical especially in times of cost pressure and rising antimicrobial resistance rates. It is in our interest to provide the best possible care for patients and in this regard a good and effective communication between the laboratory and the clinician is of vital importance.

[Application of mass spectrometry in mycology]. / Aplicación de la espectrometría de masas en micología.

MALDI-TOF (matrix-assisted laser desorption ionization time-of-flight) mass spectrometry (MS) is becoming an essential tool in most microbiology laboratories. At present, by using a characteristic fungal profile obtained from whole cells or through simple extraction protocols, MALDI-TOF MS allows the identification of pathogenic fungi with a high performance potential. This methodology decreases the laboratory turnaround time, optimizing the detection of mycoses. This article describes the state-of-the-art of the use of MALDI-TOF MS for the detection of human clinical fungal pathogens in the laboratory and discusses the future applications of this technology, which will further improve routine mycological diagnosis.

Perspectiva histórica de la espectrometría de masas en microbiología / Historical perspective of mass spectrometry in microbiology

La espectrometría de masas (EM) es una técnica de análisis que permite caracterizar muestras midiendo las masas (estrictamente las razones masa-carga) de las moléculas componentes. Cuenta con más de un siglo de historia y evolución tecnológica y a lo largo de los años ha ampliado su alcance desde los isótopos a moléculas pequeñas, moléculas orgánicas más complejas y, en las últimas décadas, macromoléculas (ácidos nucleicos y proteínas). La EM MALDI-TOF (matrix-assisted laser desorption ionization time-of-flight) es una variante que permite el análisis de mezclas complejas de proteínas y que se ha aplicado recientemente a la identificación de microorganismos en cultivo, convirtiéndose en una herramienta rápida y eficaz para el diagnóstico microbiológico que ha conseguido entrar en poco tiempo en la rutina de muchos servicios de microbiología clínica. El gran impacto que ha tenido está impulsando el desarrollo de nuevas aplicaciones en el campo de la microbiología clínica

Mass spectrometry (MS) is an analytical technique that allows samples to be characterized by measuring the masses (strictly speaking their mass-to-charge ratio) of the component molecules. This technique has been used for more than one hundred years and technological development throughout this time has broadened its scope from isotopes to small molecules, more complex organic molecules, and in the last few decades, macromolecules (nucleic acids and proteins). MALDI-TOF (matrix-assisted laser desorption ionization time-of-flight) MS is a variant that allows analysis of complex mixtures of proteins and has recently been applied to the identification of cultured microorganisms, making it a rapid and effective tool for microbiological diagnosis. In a short time, MALDI-TOF MS has become a routinely used technique in many clinical microbiology services and its strong impact is prompting the development of new applications in the field of clinical microbiology

Perspectivas de futuro de la espectrometría de masas en microbiología / Future applications of mass spectrometry in microbiology

La espectrometría de masas (EM) MALDI-TOF (matrix-assisted laser desorption ionization time-of-flight) se ha introducido con fuerza en muchos laboratorios de microbiología clínica para la identificación rápida y precisa de bacterias y hongos. De hecho, podemos considerar la implementación de esta metodología como una revolución en dichos laboratorios. Además de la identificación microbiana, la EM MALDI-TOF se está utilizando para la detección de algunos mecanismos de resistencia a los antibióticos y para la tipificación molecular de bacterias. Sin embargo, existe una serie de aplicaciones actuales y futuras que aumentan la versatilidad de esta metodología. Entre estas cabe destacar la aplicación directa a partir de muestras clínicas; la detección de toxinas o de antígenos microbianos específicos, y las aplicaciones en el campo de la virología y de la parasitología

MALDI-TOF (matrix-assisted laser desorption ionization time-of-flight) mass spectrometry (MS) has been vigorously introduced in many clinical microbiology laboratories for the rapid and accurate identification of bacteria and fungi. In fact, the implementation of this methodology can be considered a revolution in these laboratories. In addition to microbial identification, MALDI-TOF MS is being used for the detection of some mechanisms of antibiotic resistance and for the molecular typing of bacteria. A number of current and future applications that increase the versatility of this methodology may also be mentioned. Among these are its direct application on clinical samples, the detection of toxins or specific microbial antigens, and its application in the fields of virology and parasitology

High resolution laser mass spectrometry bioimaging.

Mass spectrometry imaging (MSI) was introduced more than five decades ago with secondary ion mass spectrometry (SIMS) and a decade later with laser desorption/ionization (LDI) mass spectrometry (MS). Large biomolecule imaging by matrix-assisted laser desorption/ionization (MALDI) was developed in the 1990s and ambient laser MS a decade ago. Although SIMS has been capable of imaging with a moderate mass range at sub-micrometer lateral resolution from its inception, laser MS requires additional effort to achieve a lateral resolution of 10µm or below which is required to image at the size scale of single mammalian cells. This review covers untargeted large biomolecule MSI using lasers for desorption/ionization or laser desorption and post-ionization. These methods include laser microprobe (LDI) MSI, MALDI MSI, laser ambient and atmospheric pressure MSI, and near-field laser ablation MS. Novel approaches to improving lateral resolution are discussed, including oversampling, beam shaping, transmission geometry, reflective and through-hole objectives, microscope mode, and near-field optics.

[Application of Imaging Mass Spectrometry for Drug Discovery].

Imaging mass spectrometry (IMS) can reveal the distribution of biomolecules on tissue sections. In this process, the biomolecules are directly ionized within tissue sections using matrix-assisted laser desorption/ionization, and then their distribution is visualized by pseudo-color based on the relative signal intensity. The biomolecules, such as fatty acids, phospholipids, glycolipids, peptides, proteins, and neurotransmitters, have been analyzed at a spatial resolution of 5 µm. A special instrument for IMS analysis was developed by Shimadzu. The IMS analysis does not require the labeling of biomolecules and is capable of analyzing all the ionized biomolecules. Interest in this method has expanded to many research fields, including biology, agriculture, medicine, and pharmacology. The technique is especially relevant to the drug discovery process. As practiced currently, drug discovery is expensive and time consuming, requiring the preparation of probes for each drug and its metabolites, followed by systematic probe tracking in animal models. The IMS technique is expected to overcome these drawbacks by revealing the distribution of drugs and their metabolites using only a single analysis. In this symposium, I introduced the methodology and applications of IMS and discussed the feasibility of its application to drug discovery in the near future.

Small molecule MALDI MS imaging: Current technologies and future challenges.

Imaging of specific small molecules is particularly challenging using conventional optical microscopy techniques. This has led to the development of alternative imaging modalities, including mass spectrometry (MS)-based methods. This review aims to provide an overview of the technologies, methods and future directions of laser-based mass spectrometry imaging (MSI) of small molecules. In particular it will focus on matrix-assisted laser desorption/ionization (MALDI) as the ion source, although other laser mass spectrometry methods will also be discussed to provide context, both historical and current. Small molecule MALDI MSI has been performed on a wide variety of instrument platforms: these are reviewed, as are the laser systems that are commonly used in this technique. Instrumentation and methodology cross over in the areas of achieving optimal spatial resolution, a key parameter in obtaining meaningful data. Also discussed is sample preparation, which is pivotal in maintaining sample integrity, providing a true reflection of the distribution of analytes, spatial resolution and sensitivity. Like all developing analytical techniques there are challenges to be overcome. Two of these are dealing with sample complexity and obtaining quantitative information from an imaging experiment. Both of these topics are addressed. Finally, novel experiments including non-MALDI laser ionization techniques are highlighted and a future perspective on the role of MALDI MSI in the small molecule arena is provided.

[Imaging Mass Spectrometry in Histopathologic Analysis].

Matrix-assisted laser desorption/ionization (MALDI)-imaging mass spectrometry (IMS) enables visualization of the distribution of a range of biomolecules by integrating biochemical information from mass spectrometry with positional information from microscopy. IMS identifies a target molecule. In addition, IMS enables global analysis of biomolecules containing unknown molecules by detecting the ratio of the molecular weight to electric charge without any target, which makes it possible to identify novel molecules. IMS generates data on the distribution of lipids and small molecules in tissues, which is difficult to visualize with either conventional counter-staining or immunohistochemistry. In this review, we firstly introduce the principle of imaging mass spectrometry and recent advances in the sample preparation method. Secondly, we present findings regarding biological samples, especially pathological ones. Finally, we discuss the limitations and problems of the IMS technique and clinical application, such as in drug development.

Recent methodological advances in MALDI mass spectrometry.

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is widely used for characterization of large, thermally labile biomolecules. Advantages of this analytical technique are high sensitivity, robustness, high-throughput capacity, and applicability to a wide range of compound classes. For some years, MALDI-MS has also been increasingly used for mass spectrometric imaging as well as in other areas of clinical research. Recently, several new concepts have been presented that have the potential to further advance the performance characteristics of MALDI. Among these innovations are novel matrices with low proton affinities for particularly efficient protonation of analyte molecules, use of wavelength-tunable lasers to achieve optimum excitation conditions, and use of liquid matrices for improved quantification. Instrumental modifications have also made possible MALDI-MS imaging with cellular resolution as well as an efficient generation of multiply charged MALDI ions by use of heated vacuum interfaces. This article reviews these recent innovations and gives the author's personal outlook of possible future developments.