On the fate of oxygenated organic molecules in atmospheric aerosol particles.

Highly oxygenated organic molecules (HOMs) are formed from the oxidation of biogenic and anthropogenic gases and affect Earth's climate and air quality by their key role in particle formation and growth. While the formation of these molecules in the gas phase has been extensively studied, the complexity of organic aerosol (OA) and lack of suitable measurement techniques have hindered the investigation of their fate post-condensation, although further reactions have been proposed. We report here novel real-time measurements of these species in the particle phase, achieved using our recently developed extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF). Our results reveal that condensed-phase reactions rapidly alter OA composition and the contribution of HOMs to the particle mass. In consequence, the atmospheric fate of HOMs cannot be described solely in terms of volatility, but particle-phase reactions must be considered to describe HOM effects on the overall particle life cycle and global carbon budget.

Mediastinal foregut duplication cyst of enteric type containing a persistent thymus, imitating a pericardial cyst.

UNLABELLED: Mediastinal foregut duplication cysts are rare congenital masses caused by developmental disorders of the anterior part of the embryonic primitive gut. In adults they can be discovered as an incidental finding on chest radiograph. They can mimic other intrathoracic pathologies as it was initially the case in our patient. A 51-year-old woman was incidentally found to have homogenous mass at the right cardiophrenic angle on the chest radiograph. Based on that finding and echocardiography a pericardial cyst was suspected. Computed tomography demonstrated a simple anterior mediastinal cyst. Because of the growth with a mild progression of the compression of the right atrium, the cyst was resected. Histology and immunohistochemistry revealed the mass to be a mediastinal foregut duplicatory cyst of enteric type containing persistent thymus. To our knowledge, this is the first report in which a mediastinal foregut cyst contained both enteric mucosa and ectopic persistent thymus (Fig. 9, Ref. 13). KEYWORDS: foregut cyst, mediastinal cyst, thymus, enteric cyst, pericardial cyst.

The thymus: picture review of human thymus prenatal development.

The thymus is derived from pharyngeal region; a region from which, in case of aquatic vertebrates, the gills develop. According to the classical hypothesis, the epithelial thymus stroma of human embryos is derived from the endodermal cells of the left and right ventral parts of the third pharyngeal pouches. But a close contact of the third pharyngeal pouch with its corresponding third pharyngeal clefts ectoderm plays an important role. Also an epithelial-mesenchymal interaction between the third pharyngeal pouch endoderm and surrounding neural crest derived-cells ectomesenchyme is necessary for the proliferation and differentiation of thymic epithelial cells. In our work we photographically presented the development of thymus from the 6th up to the 25th week of development. The first primordia of the thymus and parathyroid glands within the endoderm of third pharyngeal pouches can be seen in 8 to 9 mm stages. We found also an epithelial proliferation in the second pharyngeal pouches, but this "thymus secundus" stopped their differentiation. The thymus primordia at the 7th and 8th week of development contain almost exclusively epithelial cells. These cells are arranged at the periphery as a row of prismatic cells. The mesenchyme accumulates around the epithelial thymic primordium, and during 9th to 12th weeks of development, septa from mesenchyme fold between the epithelial cells and create the "openings" in the capsular surround. According to our observations, in the 13th week of development the differentiation of cortex and medulla becomes obvious and is completed from the 17th up to 18th week of development onward. The first developing Hassall's corpuscle was detected in the 13th week of development. The striking increase in the number of the Hassall's bodies was observed between the 16th and the 18th week of development, as well as between the 22nd and the 25th week of development (Fig. 14, Ref. 35).

Merkel cells--review on developmental, functional and clinical aspects.

The objective of this review is to introduce Merkel cells, to provide a basic overview on the theoretical background of function, development and clinical importance of Merkel cells. Merkel cells (MCs) are post-mitotic neuroendocrine cutaneous cells primarily localized in the epidermal basal layer of vertebrates and concentrated in touch-sensitive areas in glabrous, hairy skin and in some mucosa. There is a great site variation in the density of MCs. In routine light microscopy human MCs can hardly be identified. Cytokeratine 20 is a reliable marker with highest degree of specifity. MCs can be also distinguished by electron microscopy. The origin of human MCs has been controversial. Some investigators believe that it is a neural crest derivate, whereas others have proposed that it is a differentiation product of the fetal epidermal keratinocytes. Most studies focus on neuroendocrine functions and their possible malignant transformation into Merkel cell carcinomas (MCC). MCC is an uncommon and often aggressive malignancy and found mainly in elderly patients. It occurs most frequently in the head and neck region. MCC may be difficult to diagnose, it appears as a firm, painless lump. Diagnosis is based on typical histology representation on haematoxylin-eosin stained slides together with the results of immunohistochemistry. Histologically, MCC has been classified into three distinct subtypes: trabecular, intermediate and small cell type. Radical surgery is the recomended procedure for the treatment of primary MCC. Oncological treatment is generally reserved for stage III. (distant metastases) cases of MCC (Tab. 1, Fig. 13, Ref. 58). Full Text in free PDF www.bmj.sk.

Thymic Hassall's bodies of children with congenital heart defects.

The development of the thymus and heart are closely related while in both, the neural crest cells play an important role. In our preliminary study, the thymic microscopic structures of the infant's thymuses with the congenital heart defects were observed. The study was conducted on 36 specimens of newborn thymuses removed due to surgery for cardiovascular malformations. Standard formalin-fixed paraffin-embedded tissue technique was used. Five-microm-thick sections were stained with hematoxylin and eosin and the microscopic examination was focused on the structure of Hassall's bodies. The Hassall's bodies showed considerable variations in size as well as in quantity. In most cases, the Hassall's bodies were large with the heterogeneous amorphous material enclosed in cystic dilatations. This type of Hassall's bodies is typical for adult thymuses. The most conspicuous changes (huge Hassall's bodies with the cystic dilatation filled up with cell detritus) were observed in patients with ventricular septal defect, atrioventricular septal defect and tetralogy of Fallot. Small-sized Hassall's bodies corresponding with infant age, were observed in cases with pulmonary valve atresia, atrial septal defect and in some cases of transposition of great arteries. We assume that the changes of microenvironment of the thymic medulla are associated with disrupted migration of the neural crest cells which are essential in the normogenesis of both heart and thymus (Tab. 1, Fig. 12, Ref. 33).

Endocrine organs and laser scanning confocal microscopy (LSCM) imaging: vascular bed in human spleen.

OBJECTIVE: This work was aimed to utilize the precise method of laser confocal microscopy (LSCM) to depict the image of spatial relationships of the vessel network in the tissue structures of the human spleen. METHODS: With the use of serial paraffin or vibratome sections of more than 20 µm thickness infiltrated with eosin fluorescence dye the images of arterial and venous walls of different calibres, capillaries, and venous sinuses were morphologically revealed. RESULTS: Venous sinuses were frequently found to create mutually communicating branches and their lining projected into the lumen protruding cells with distinct spherically or ovally shaped nuclei, positioned on the brightly fluorescent and fragmented lamina basalis. The presence of lymphocytes was distinct in periarteriolar lymphoid sheath (PALS) and lymphatic follicles. Lining cells of the red pulp veins sporadically contained marked eosinophilic granules. CONCLUSION: The method of LSCM allowed: 1. to reveal two-dimensional and sharp image of the human spleen structures, 2. to investigate the vertical course of venous structures in the tissue, 3. to obtain serial optic sections in z axis to their maximum spatial projections. These data will also serve for the creation of three-dimensional images of vessel network in the human spleen in the future studies.

Anthropometry, nutrition status and thymic size of Gypsy newborns from southwestern Slovakia.

Gypsy population represents a specific minority in Slovakia that differs from the majority population by its origin and genetic markers, as well as by generally lower social and economic status and lower hygienic standards of living. The aim of the present work is the analysis of anthropometric dimensions and indexes, as well as of thymus size, in the group of Gypsy and non-Gypsy newborns from the Southern Slovakia. Our group of 212 physiological newborns consisted of 33 Gypsy and 179 non-Gypsy newborns. All newborns were underwent anthropometric examination and their thymus size was assessed by ultrasonography and calculated as so-called Thymic Index". Gypsy newborns show statistically significant lower anthropometric dimensions (birth weight and birth body length, head and chest circumference) when compared to non-Gypsy newborns, however, they do not differ in the values of nutritional status indicators (arm circumference, Quételet index and Rohrer index). They do not differ even in the thymus size that can be regarded as a "barometer" of the nutrition and of some negative stimuli. In spite of generally deficient nutrition and lower health status of the Gypsy minority in Slovakia, we did not find any significant differences in the indicators of nutritional status or in thymus size (Tab. 2, Ref. 34).

[Formation of the papillary surface of the hands and feet in prenatal development in man]. / Formovanie papilárneho terénu rúk a nôh v prenatálnom vývine cloveka.

The development of the papillary terrain on the fingers and toes, palms and soles was studied in 36 fetuses of gestational age ranging from 9 to 26 weeks. Histologic methods on serial sections and studies of the dermal surface of the skin after removal of the epidermis (according to Okrajima) were the main approaches used. The morphogenesis of papillary crests is described at different developmental stages and factors involved in their origin are discussed.

Human lymphoblastoid cells in long-term cultures: electron microscopic study.

Fine structure of lymphoblastoid cell lines (LCL) derived from leukocytes of three patients with acute myelosis and one patient with undifferentiated acute leukemia were studied repeatedly by electron microscope. The majority of cells in all lines was of the same primitive lymphoblastic type as refered to in literature regardless to their origin. Morphology of the cells did not change with time of cultivation for several months, by freezing and thawing and by new recultivation after prolonged cryopreservation. No morphologic signs of contamination by viruses were found. No evident morphologic signs of differentiation to mature granulocytes or "mature" lymphocytes or plasmatic cells were observed.