Quantification of SARS-CoV-2 monoclonal IgG mass fraction by isotope dilution mass spectrometry.

The availability of serology assays to measure antibodies against the SARS coronavirus 2 (SARS-CoV-2) expanded rapidly during the Covid-19 pandemic. The interchangeable use of such assays to monitor disease progression and immune protection requires their standardization, for which suitably characterized monoclonal antibody materials can be useful. The methods, based on isotope dilution mass spectrometry, to value assign the mass fraction of such a material in solution within the context of an international interlaboratory comparison study (CCQM-P216) are described. The mass fraction in solution of a humanized IgG monoclonal antibody (mAb) against the SARS-CoV-2 Spike glycoprotein in the study sample has been value assigned through a combination of liquid chromatography, isotope dilution mass spectrometry (LC-ID-MS) methods and size exclusion chromatography with UV detection (SEC-UV). The former were developed for the quantification of amino acids and proteotypic peptides as surrogate analytes of the mAb while the latter was applied for the determination of the relative monomeric mass fraction. High-resolution mass spectrometry (hrMS) allowed the molecular weight evaluation and ruled out the presence of significant impurities. Method trueness was assessed using a subclass homologous IgG1 material value assigned by amino acid analysis. The assigned mass fraction of monomeric SARS-CoV-2 IgG in solution was 390 ± 16 mg/g. The associated expanded uncertainty originated mainly from acid hydrolysis variability and Trypsin/Lys-C digestion variability and efficiency.

Metrological challenges for measurements of key climatological observables: Oceanic salinity and pH, and atmospheric humidity. Part 1: Overview.

Water in its three ambient phases plays the central thermodynamic role in the terrestrial climate system. Clouds control Earth's radiation balance, atmospheric water vapour is the strongest "greenhouse" gas, and non-equilibrium relative humidity at the air-sea interface drives evaporation and latent heat export from the ocean. On climatic time scales, melting ice caps and regional deviations of the hydrological cycle result in changes of seawater salinity, which in turn may modify the global circulation of the oceans and their ability to store heat and to buffer anthropogenically produced carbon dioxide. In this paper, together with three companion articles, we examine the climatologically relevant quantities ocean salinity, seawater pH and atmospheric relative humidity, noting fundamental deficiencies in the definitions of those key observables, and their lack of secure foundation on the International System of Units, the SI. The metrological histories of those three quantities are reviewed, problems with their current definitions and measurement practices are analysed, and options for future improvements are discussed in conjunction with the recent seawater standard TEOS-10. It is concluded that the International Bureau of Weights and Measures, BIPM, in cooperation with the International Association for the Properties of Water and Steam, IAPWS, along with other international organisations and institutions, can make significant contributions by developing and recommending state-of-the-art solutions for these long standing metrological problems in climatology.

Accurate quantification of impurities in pure peptide material - angiotensin I: Comparison of calibration requirements and method performance characteristics of liquid chromatography coupled to hybrid tandem mass spectrometry and linear ion trap high-resolution mass spectrometry.

RATIONALE: The prohormone angiotensin I (ANG I) [amino acid sequence: DRVYIHPFHL] and other structurally related peptide hormones play an essential role in the regulation of the water and electrolyte balance in the human body as well as blood pressure. ANG I is a biomarker for hypertension and diabetes. Therefore, well-characterized pure reference materials and comparable and SI-traceable analytical characterization methods are required to establish reference measurement systems (RMS) for laboratory medicine. METHODS: Two analytical characterization methods based on liquid chromatography/mass spectrometry (LC/MS) systems with electrospray ionization have been developed and validated in-house. Both high-resolution MS (hrMS) and hybrid-tandem MS/MS were used for the identification and quantification of the major structurally related peptide impurities of ANG I. The impurities were quantified by use of external calibrations with original impurity standards. Mass fraction impurity values and corresponding expanded measurement uncertainties were calculated. RESULTS: Five structurally related degradation products were detected as major impurities in a 'pure' ANG I material. The peptides ANG (2-10) [RVYIHPFHL], ANG II [DRVYIHPF] and three ANG I isomers [DRVYLHPFHL, DRVYIHPFHI and DRVYLHPFHI] were identified and corresponding mass fraction values calculated that range from 0.66 to 4.86 mg/g. CONCLUSIONS: The mass fraction values for the major related peptide impurities in the ANG I material obtained with both LC/hrMS and LC/MS/MS systems are in excellent agreement. This study emphasizes the importance of mass spectrometric techniques for application to mass balance approaches for mass fraction value and uncertainty assignment of impurities in 'pure' substance reference materials for peptides.

Impurity identification and determination for the peptide hormone angiotensin I by liquid chromatography-high-resolution tandem mass spectrometry and the metrological impact on value assignments by amino acid analysis.

It is common practice to quantify the mass concentration of a peptide solution through quantitative determination of selected chemically stable amino acids produced following complete hydrolysis of the parent peptide. This is because there is generally an insufficient quantity of material available to allow for the obvious alternative of a direct purity analysis characterization of the parent peptide, and the subsequent constitution of a calibration solution. However, selected accurately characterized pure peptide reference materials are required to establish reference points for the dissemination of metrologically traceable measurements and to develop reference measurement systems for laboratory medicine. In principle, purity assignment of a peptide can be performed by using the so-called mass balance approach, by employing a range of analytical techniques to obtain an estimate of the mass fraction content of all impurities present in the intact peptide, and by utilizing the difference from the theoretical limit value to assign the mass fraction content of the main peptide. Liquid chromatography-high-resolution tandem mass spectrometry (LC-hrMS/MS) is a key technique for the detection, identification, and determination of structurally related impurities present in a peptide material, and experiments characterizing the model peptide hormone angiotensin I (ANG I) are described in the present work. Degradation products that were generated from ANG I after storage at elevated temperatures were screened. The formation of peptide fragments such as ANG II or ANG III was determined by comparison of measured mass values with calculated mass values. The use of a data-dependent acquisition technique enabled the detection and structural characterization of ANG II and other peptide fragments as major impurities in the same LC-hrMS/MS analysis run. Subsequent quantification using external calibration allowed the mass fraction of the major impurities in a candidate reference material to be estimated as 10.4 mg/g. Failure to correct for these impurities would lead to a 1% error in the determination of the concentration of the peptide in solution by amino acid analysis techniques.

[Heerman's principle in microsurgery of nasal cavity and paranasal sinuses].

Forty-year experience in surgical activity of an otorhinolaryngological department of A. Krupp's hospital in Essen, Germany, is reviewed. Main lines of Heerman's conception are shown in conduction of surgical interventions on the nasal cavity and paranasal sinuses, lacrimal tracts. Various endonasal interventions are performed with employment of endoscopes and surgical microscopes except malignant tumors, oroantral fistulas, malformations. The necessity of gain of surgical skill while operating corpses is emphasized.

International comparability of chemical measurement results.

The international system of units (SI) is an internationally recognized system based on standards of long-term stability; by the use traceable measurements it provides an international infrastructure for realizing comparable measurements. The work of the Consultative Committee for Amount of Substance (CCQM) and the implementation of the Mutual Recognition Arrangement (MRA) are facilitating an international programme for metrology in chemistry to extend this infrastructure to the field of chemical measurements. The major points of this programme, which include the execution of international comparisons and the construction of a key comparison and calibration database at the BIPM, are described.

[Palisade cartilage tympanoplasty in reconstructing almost total defects of tympanic membrane: own experience]. / Technika palisadowa w odtwarzaniu prawie calkowitych ubytków blony bebenkowej--doswiadczenia wlasne.

The authors described 8 patients with almost total defects of tympanic membrane. The patients were operated on with palisade tympanoplasty technique (m. Heermann) with the use of conchal autografts for reconstruction of the tympanic membrane. The technique is very useful and gives good results.

[Influence of the anatomical structure of the uncinate process on bone patency of the maxillary sinus: a radiological and clinical evaluation]. / Wplyw typu budowy anatomicznej wyrostka haczykowatego na droznosc ujscia zatoki szczekowej--ocena radiologiczno-kliniczna.

The group of 185 patients with chronic and acute recurrent rhinosinusitis was analyzed radiologically with CT scans. The anatomical structure of the uncinate in its upper part, configuration and position of its low margin were evaluated. The results have been compared to the normal CT scans of paranasal sinuses of 50 persons without any sinus disease. The significant correlation was found between the shape and the development of pneumatization of the turbinate and the configuration of the uncinate process as well as to its type. The degree of the pneumatization and configuration or hypertrophy of the turbinate correlate also to the maxillary sinus disease.

[Microscopic endonasal sinus surgery (MESS) in nasal polyposis: long term results]. / Mikrochirurgia endonasalna zatok w leczeniu polipów nosa: wyniki odlegle.

The endonasal microscopic sinus surgery (EMSS) in polyposis nasi is a grateful and in most cases successful procedure with a relative low risk of complications. In 1988 and 1989 we operated on 302 patients with polyposis nasi following the "Heermann Concept of EMSS". In each case the total ethmoidectomy with maxillary, sphenoid and frontal sinus surgery was performed. After an average of 5.2 years we started a follow-up in 185 patients including a questionnaire and clinical examination with endoscopic control and olfactometry. We found recurrent polyposis in 17.3% and a reoperation was necessary only in 6.5%. The complaints in polyposis as nasal obstruction, frontal cephalgia and hyposmia could be improved in more than 80%. About 26.5% of our patients suffered from bronchial asthma. Every second of them (51%) saw an improvement of asthma complaints after the operation. It is remarkable, that the clinical and endoscopic findings do not correlate in all cases with the subjective judgement of the patients. We saw patients with manifest recurrent polyposis, who did not deplore any complaints and vice versa. At last 85.4% said, that they would undergo the operation again.

[The Heermann modification of intranasal microsurgery in lacrimal duct stenoses]. / Die Heermann-Modifikation der intranasalen Mikrochirurgie bei Tränenwegstenosen.

The authors demonstrated Heermann's modification of intranasal microsurgery on the tearways. Since 1912 all intranasal lacrimal sac operations at the Krupp Hospital (up to 98 cases yearly) have been performed according to Randolph and West (1909). During the last 36 years our patients have been operated on in a semisitting-(Fowlers)-position with the help of the binocular microscope and with hypotensive anaesthesia. This technique of lacrimal sac surgery is demonstrated "step-by-step" with the removal of the medial wall of the lacrimal sac in abscesses or dacryoliths. In rare cases of a presaccal stenosis, a circular resection of the stenosis after J. Heermann (1989/1991) was done to leave the common duct open by the retraction of the scar. That is the reason why the insertion of plastic prostheses is rarely necessary (only in patients with congenital aplasia or extensive stenosis of the horizontal lacrimal duct). Funnel-shaped prostheses of glass were developed in 1925 by J. Heermann sen., of steel 1930 by H. Heermann and made by plastic material 1966 by J. Heermann. During a ten-year period (1976-1986) we evaluated 659 cases of intranasal microsurgery on the tearways. The use of plastic prosthesis was necessary in 17 cases. Including reoperations (first operation after Toti) satisfactory results were obtained in 94% of all cases.

[Intranasal microsurgery in treatment of cerebrospinal rhinorrhea]. / Mikrochirurgia wewnatrznosowa w leczeniu plynotoku nosowego.

The authors describe two female patients with CSF-leakage. The first patient showed spontaneous CSF rhinorrhea from a leak in the posterior wall of the sphenoid sinus and the second one showed a traumatic fistula in "lamina cribrosa" area. The treatment of choice is closure of the CSF leakage by nasal surgeon (intranasal and with help of binocular microscope under hypotensive anaesthesia) using either intranasal-transseptal or intranasal-transethmoidal approach). This preserves olfaction and avoids the risk of a neurosurgical or paranasal methods. The diagnosis of CSF rhinorrhea can be established by beta-2 transferrin test, isotope scanning or fluorescence endoscopy. The high-resolutions CT is the best method for localization of the bone defect. The intranasal interposition of fascial or conchal grafts with use of fibrigen glue in cases of small defect (< 1-2 cm) is always successful.

[Pathogenesis of rhinosinusitis and endonasal microsurgery]. / Patogeneza schorzen zapalnych zatok przynosowych i mozliwosci leczenia wewnatrznosowa technika mikrochirurgiczna. Czesc I.

The functional microsurgery of the nose has been carried out with help of microscope since 1958 by H. Heermann. The authors described the importance of mucociliary system and lateral nasal wall for pathogenesis and diagnosis of recurring and chronic rhinosinusitis. By the means of nasal endoscopy and polytomography the infection foci can be exactly localised. The list of indications corresponds to our actual concept.

[Endonasal microsurgery by Heermann++. Part II]. / Mikrochirurgia wewnatrznosowa metoda Heermanna. Czesc II.

Endonasal sinus surgery in the case of inflammatory disease is of increasing importance. The maxillary, ethmoid, sphenoid and frontal sinus operations as well as the septumplasty are performed microsurgically. There are only few indications, when the intranasal procedure cannot be applied. We prefer all intranasal operations with the patient placed in semi-Fowler's position with hypotensive anaesthesia. Out of a total of 310 cases in which endonasal microsurgery was performed, 251 were submitted to a retrospective study 12-36 months after the operation. In our study there was an operative success rate of 92.8%. No complications such as: CSF leakage, persisting postoperative visual or ocular disturbance or vascular complications were observed. Compared with transfacial or external sinus surgery, the advantage of the transantral microsurgical technique are better functional results, fewer complications an a reduced duration of hospitalization.