Survival in foods of Staphylococcus aureus grown under optimal and stressed conditions and the effect of some food preservatives

Staphylococcus aureus was grown in a rich peptone medium which became alkaline with continued incubation. Cells were grown at 37 degrees C and in the same medium containing 1 M NaCl at 46 degrees C, a temperature at which this organism can grow only when protected by NaCl. Cells of these cultures are hereafter called 37 degrees C-cells and 46 degrees C-cells, respectively. The 37 degrees C-cells harvested when the pH was 7.1 to 7.7 had decimal reduction times (D60-value) of 1.8 to 3.1 min in 50 mM pH 7.2 Tris buffer. The D60 value of 46 degrees C-cells tested in the same way, harvested from cultures at pH 6.6 to 7.6, ranged from 5.3 to a maximum of 12.8 min. In milk, green beans, peas, or beef slurry, the D60-value of 46 degrees C-cells was about four times higher than that of 37 degrees C-cells. Length of survival after freeze-drying in skim-milk powder exposed to air was longest for the cells with the highest D-value. In freeze-dried peas and media acidified with acetic and lactic acids, 46 degrees C-cells survived longer than 37 degrees C-cells. However, the sensitivity of the two kinds of cells to potassium sorbate, sodium benzoate, and sodium propionate was essentially the same, but the 46 degrees C-cells were more resistant to butylated hydroxyanisole and sodium nitrite.     

Quantitative changes in the frequency and distribution of the C-cell population in the rat thyroid gland with age

Summary The development of calcitonin cells (C-cells) was investigated in rat thyroid glands from birth to 120 days, using an immunoperoxidase technique and a point-counting method. The proportion of C-cells to follicular cells was 4.5% on the day of birth and increased progressively to 10.4% by 120 days. The highest density of C-cells was noted in the mid-region of the lobes along a longitudinal axis. The caudal and cephalic regions of the lobes contained smaller numbers of C-cells. The C-cells tended to be more numerous in the posterior aspects of the lobes. Although the numbers of C-cells in 120-day-old animals were markedly increased as compared to animals at the time of birth, the cell distributions within the glands were similar at all ages.     

Production of monoclonal antibodies against a novel glycoprotein synthesized and secreted by dog thyroid C-cells.

A monoclonal antibody (MAb) that reacted only with thyroid C-cells was raised against cell suspensions from dog thyroid glands, to examine a glycoprotein secreted by C-cells. After chronically-induced hypercalcemia and administration of an anti-thyroid drug, reaction products for the antibody markedly decreased in C-cells, coinciding with alterations in calcitonin immunoreactivity. The antigen recognized by the MAb appears to be a secretory protein. The MAb reacted with C-cells from a wide variety of mammalian species, including rats, mice, hamsters, cattle, cats, rabbits, and monkeys. Furthermore, tumor cells of human medullary thyroid carcinoma, which is derived from C-cells, were immunoreactive to the MAb. Exceptionally, C-cells from guinea pigs and pigs were not stained with the MAb. No crossreactivity was observed in any of the dog tissues examined. Immunoblot analysis demonstrated that the MAb recognized a single prominent band at a molecular weight of approximately 79,000. The 79 KD band reacted with various digoxigenin-labeled lectins, including GNA, DSA, SNA, and MAA; it is a glycoprotein containing mannose, N-acetylglucosamine, and sialic acid. Dog thyroid C-cells were also densely stained with these lectins. The results indicate that thyroid C-cells synthesize and secrete a specific glycoprotein in addition to peptide hormones.     

Quantitative changes of the C-cell population in the rat thyroid during postnatal ontogenesis

Summary The number and distribution of C-cells in the rat thyroid gland, have been investigated during postnatal ontogenesis from birth to 120 days of age. The argyrophilic and metachromatic properties of these cells were used to identify them. In the thyroid of newborn rats the C-cells do not exhibit argyrophilia and metachromasia. These reactions appear at 10 days and can be seen at all subsequent ages. The number of C-cells shows a parallel increase with age as demonstrated by the change in the proportion of C-cellsF-cellscolloidstroma during development. A marked increase in C-cells was found at 50 days of age when the proportion of C-cells rose to 27.67% from the value of 16.78% at 30 days. At 70 days a decrease was noted (20.50%) which hardly changed until 120 days of age (22.20%). The numerical increase in C-cells occurs at the expense of the follicular epithelium and stroma.The C-cells occupy elongated islet-like region in the central part of the lobe, decreasing in number towards the periphery where no C-cells are present. The long axis of the C-cells area is parallel with the longitudinal axis of the lobe. The area of C-cells is largest at the centre of the lobe, corresponding to the territory of the peak of the Gaussian curve for the numerical distribution of C-cells.     

Effects of ethanol on the ultrastructure of the hamster thyroid C-cell

The morphology of the thyroid C-cells in golden hamsters after short- and long-term treatment with ethanol was studied. Immunohistochemistry was applied to examine the distribution of the C-cells in the thyroid gland. In the short-term experimental animals, the Golgi complexes and the granular endoplasmic reticulum were well developed and the number of the secretory granules was decreased as compared with those of the control animals. These findings suggest that the cellular activity of the thyroid C-cell is stimulated after short-term treatment with ethanol. The morphology of the thyroid C-cells of the long-term experimental animals was similar to that of the controls. It is conceivable that long-term treatment with ethanol does not affect the function of the C-cell.     

Effects of dosed sympathectomy on the development of adaptation-compensation reaction of C-cells of the thyroid gland and chromaffin cells of the adrenal glands in young rats

Using radioimmunological, morphometrical, electron microscopic and luminescent methods, comparative analysis of thyroid C-cells and adrenal chromaffin cells has been carried out at guanethidine sympathectomy in young rats. Significant decrease of functional activity of C-cells with concomitant hyperplasia of C-cells population under blockade of sympathetic influences has been revealed. Compared to C-cells, adrenal chromaffinocytes of sympathectomized rats possess higher degree of structural-functional mobilization and are characterized by intensive secretion of catecholamines directed at restoration of tissue neurotransmitter deficit.     

Reactivity of monoclonal islet cell antibodies on normal hyperplastic and neoplastic thyroid C-cells

Summary Thyroid C-cell reactivity to 15 monoclonal antibodies raised against a series of pancreatic islet cells (H[human]ISL, B[bovine]ISL and R[rat]ISL) was evaluated using an indirect immunoperoxidase technique on frozen thyroid sections. Of the monoclonal anti-islet cell antibodies, five reacted specifically with bovine C-cells or human hyperplastic and neoplastic C-cells but not with follicular cells. Two monoclonal antibodies of the bovine series showed strong immunoreactivity with C-cells and only a weakly positive immunostaining of follicular cells. Five monoclonal antibodies reacted with both thyroid C-cells and follicular cells, whereas 3 monoclonal anti-islet cell antibodies did not stain any cell type of the thyroid. In human medullary carcinomas, calcitonin- and somatostatin-producing neoplastic cells were immunoreactive with the same monoclonal antibodies as were normal human C-cells. The protein bands identified by the monoclonal antibodies in human medullary carcinomas had the same molecular weight as those from pancreatic islet extracts. Our study demonstrates the presence of similar differentiation antigens on thyroid C-cells and pancreatic islet cells; this further illustrates common modes of differentiation and specialisation of these embryologically different members of the dispersed neuroendocrine system. The crossreactivity of seven of the monoclonal antibodies investigated with follicular epithelium of the thyroid suggests the existence of common antigenic determinants in different endocrine organs and may partly explain the multiple organ autoimmune response found in patients with polyendocrine diseases.     

S-100 protein and neuron-specific enolase in parathyroid glands and C-cells of the thyroid

Normal parathyroid glands and parafollicular cells (C-cells) of man, rat and rabbit, and also human parathyroid adenomas and medullary carcinomas were investigated for the presence of S-100 protein and neuron-specific enolase (NSE). For determination of the proteins immunoperoxidase methods were applied, i.e., the PAP method and the avidin-biotin system. The antisera, of polyclonal origin, were specifically directed against cow S-100 protein and rat or bovine NSE. The respective antisera are known to crossreact with S-100 protein from man, rat, and rabbit, as well as with NSE from man and rat. Surprisingly, the test for S-100 protein was found to be strongly positive in the parathyroid glands of rat and rabbit and was focally positive in normal and adenomatous human parathyroid glands, but completely negative in C-cells and medullary carcinoma cells. NSE was present in C-cells of rat and man, and in medullary carcinoma cells, but was absent in normal and adenomatous parathyroid cells. The results support data that indicate that both parathyroid cells and C-cells are derived from elements of the neural crest, but undergo different maturation processes during embryological development.     

S-100 protein and neuron-specific enolase in parathyroid glands and C-cells of the thyroid

Summary Normal parathyroid glands and parafollicular cells (C-cells) of man, rat and rabbit, and also human parathyroid adenomas and medullary carcinomas were investigated for the presence of S-100 protein and neuron-specific enolase (NSE). For determination of the proteins immuno-peroxidase methods were applied, i.e., the PAP method and the avidin-biotin system. The antisera, of polyclonal origin, were specifically directed against cow S-100 protein and rat or bovine NSE. The respective antisera are known to crossreact with S-100 protein from man, rat, and rabbit, as well as with NSE from man and rat. Surprisingly, the test for S-100 protein was found to be strongly positive in the parathyroid glands of rat and rabbit and was focally positive in normal and adenomatous human parathyroid glands, but completely negative in C-cells and medullary carcinoma cells. NSE was present in C-cells of rat and man, and in medullary carcinoma cells, but was absent in normal and adenomatous parathyroid cells. The results support data that indicate that both parathyroid cells and C-cells are derived from elements of the neural crest, but undergo different maturation processes during embryological development.     

Laminin-induced process outgrowth from isolated fetal rat C-cells.

A method for isolation of C-cells from rat fetuses was developed, and the morphological plasticity of the cells in primary culture systems was tested. Thyroid-parathyroid-ultimobranchial body (UB) complexes from 16-day rat fetuses were treated with 0.1% collagenase and 1000 PU/ml Dispase at 37 degrees C for 1 h. After dissociation by pipetting, UBs were obtained as remaining cell aggregates with diameters of 150-200 microns. The isolated UBs were cultured on untreated, fibronectin-coated, or laminin-coated substratum in Dulbecco's modified Eagle's medium/Ham's nutrient mixture F-12 (1:1) supplemented with 5% fetal calf serum. In some experiments, the medium was changed to serum-free medium after 24 h of incubation, until the UBs had formed cell sheets. At Day 4 in vitro, the cultures were subjected to immunostaining using anti-calcitonin antiserum. On untreated or fibronectin-coated substratum, most of the C-cells exhibited polygonal or ovoid shapes, and 5-8% of them were found to project processes. On laminin-coated substratum, the ratio of process-bearing C-cells to total C-cells was 23% in serum-supplemented medium and 51% in serum-free medium. The longest processes reached 150 microns in length. The processes were intensely reactive with anti-alpha-tubulin antibody and were completely disintegrated by colcemid, suggesting that the microtubule cytoskeleton participated in the maintenance of the processes. Thus it was demonstrated that fetal rat C-cells are still responsive to environmental signals, such as laminin, and extend neuritic processes.     

Effect of weightlessness and artificial gravitation on thyroid gland morphology]

The investigation of the thyroid gland was carried out in Wistar rats, SPF colony 4.5--13 h and 25 days after a 18.5 days flight on board the space biosatellite "Cosmos-936". In animals subjected to weightlessness, moderate symptoms of the thyroid hypofunction were observed, statistically significant decrease in number and volume of the nuclei in calcitonin-secreting cells (C-cells) was especially pronounced during 4.5--9 h after landing. Similar but less pronounced changes were observed in C-cells of the rats subjected to artificial conditions of space flight, besides weightlessness. The similarity of the changes in the animals of both groups made it possible to connect the increasing amount of C-cells and the morphological symptoms of their functional inhibition with the effect of weightlessness and hypokinesia. During the space flight, the animals were kept under the conditions of artificial gravitation on board the biosatellite and therefore morphological peculiarities specific for the earth conditions were preserved in C-cells and the thyroid gland. Thus, it was concluded that artificial gravitation prevented the development of the thyroid changes which appeared under the influence of weightlessness.     

Desmosomes of follicular cells and C-cells in the thyroid gland of rats]

Well developed desmosomes can be seen between the C-cells and follicular cells in the rat thyroid gland. They are structurally similar to the desmosomes at the boundaries of homotypic cells. This observation speaks in favour of the development of C-cells from the initial cells of thyroid embryonic analage.     

Identification of early developing axon projections from spinal interneurons in the chick embryo with a neuron specific beta-tubulin antibody: evidence for a new 'pioneer' pathway in the spinal cord

The early development of interneurons in the chick embryo spinal cord was studied using a monoclonal antibody against a neuron-specific beta-tubulin isoform. Early developing interneurons were divided into two cell groups on the basis of their location and the pattern of growth of their axons. One group is composed of cells that establish a primitive longitudinal pathway (PL-cells), whereas the other group contains cells constituting a circumferential pathway (C-cells). The onset of axonal development in both cell groups occurs at stage (st.) 15 (embryonic day, (E), 2) in the branchial segments, which is prior to axonogenesis of motoneurons. PL-cells develop in the region between the floor plate and the motoneuron nucleus. Their axons are the first neuronal processes ('pioneer axons') to arrive in the ventrolateral marginal zone and they project both rostrally and caudally to establish a primitive longitudinal association pathway at the ventrolateral surface of the neural tube. This pathway is formed before axons of C-cells arrive in the ventrolateral region. The first C-cells are initially located in the most dorsal portion of the neural tube, whereas later appearing C-cells are also located in both intermediate and ventral regions of the neural tube. The axons of C-cells project ventrally, without fasciculating, along the lateral border of the neural tube. Some of their axons enter the ipsilateral ventrolateral longitudinal pathway at st. 17. We often observed apparent contacts and interactions between preexisting axons of PL-cells and newly arriving axons of C-cells. The axons of commissural C-cells first enter the floor plate at st. 17 and cross the midline at st. 18. Axons of C cells begin to join the contralateral ventrolateral longitudinal pathway at st. 18+ to st. 19. In the floor plate region, contacts between growth cones and axons were often observed. However, axons in the floor plate at these stages were not fasciculated. These observations establish the timing and pattern of growth of axons from two specific populations of early developing interneurons in the chick spinal cord. Additionally, we have identified an early and apparently previously undescribed 'pioneer' pathway that constitutes the first longitudinal pathway in the chick spinal cord.     

An ultrastructural study of the cysts in chicken ultimobranchial glands,with special reference to C-cells

Summary The ultimobranchial glands of the chicken were examined by electron microscopy and immunocytochemistry using a calcitonin antiserum. Electron microscopy confirmed the presence of C-cells, containing numerous secretory granules storing calcitonin, in the luminal lining of cyst-like structures found in these glands. These cells were furnished with prominent microvillar projections at their luminal surface, and the cytoplasm of the apical region was filled with fibril material. Furthermore, the cells contained prominent junctional complexes and desmosomes at their apico-lateral surfaces. In these C-cells, secretory granules were concentrated near the lumen and some were attached to the apical cell membrane. The luminal content of the cysts had a colloid-like and flocculent appearance, and was frequently seen attached to the cytoplasmic projections or apical cell membrane of the C-cells. Since the cysts progressively increase in volume and number with age, it is suggested that they may partly play a role in the storage of excess or unneeded hormonal products.     

Postnatal variations in the number and size of C-cells in the rat thyroid gland

The heterogeneous distribution of thyroid C-cells has until now hindered an objective evaluation of changes caused by age or experimental stimuli. To overcome this, a rigorous methodology has been designed to detect variations in shape, size, and number of C-cells throughout development. Using this methodology, we have demonstrated that C-cells do not significantly alter their shape with age. However, their volume increases gradually from 472 m³ in newborn rats to 1653 m³ in 120-day-old animals. Over the same time period, the mean number of C-cells within the thyroid gland increased 9-fold (from 1.6x10⁴ to 1.5x10⁵), and the number of C-cells per unit area decreased (from 6.15x10⁴/mm³ to 2.6x10⁴/mm³). We conclude that there are marked variations in size, total number, and number of C-cells per unit area in the rat thyroid gland after birth.     

Thyrotropin-releasing hormone receptor expression in thyroid follicular cells: a new paracrine role of C-cells?

Thyrotropin-releasing hormone (TRH) synthesized in the hypothalamus has the capability of inducing the release of thyroid-stimulating hormone (TSH) from the anterior pituitary, which in turn stimulates the production of thyroid hormones in the thyroid gland. Immunoreactivity for TRH and TRH-like peptides has been found in some tissues outside the nervous system, including thyroid. It has been demonstrated that thyroid C-cells express authentic TRH, affecting thyroid hormone secretion by follicular cells. Therefore, C-cells could have a paracrine role in thyroid homeostasis. If this hypothesis is true, follicular cells should express TRH receptors (TRH-Rs) for the paracrine modulation carried out by C-cells. In order to elucidate whether or not C-cell TRH production could act over follicular cells modulating thyroid function, we studied TRH-Rs expression in PC C13 follicular cells from rat thyroid, by means of immunofluorescence technique and RT-PCR analysis. We also investigated the possibility that C-cells present TRH-Rs for the autocrine control of its own TRH production. Our results showed consistent expression for both receptors, TRH-R1 and TRH-R2, in 6-23 C-cells, and only for TRH-R2 in PC C13 follicular cells. Our data provide new evidence for a novel intrathyroidal regulatory pathway of thyroid hormone secretion via paracrine/autocrine TRH signaling.     

Compensatory-adaptive modifications of the C-cell apparatus of the thyroid in normal rats of various ages and in partial sympathectomy

Population of the thyroid C-cells, normal and at sympathectomy has been analyzed in 75 white male rats at the age of 1, 3 and 6 months by means of electron microscopical, morphometrical and radioimmunological methods. Partial sympathectomy has been performed using subcutaneous injection of guanethidine (15 mg/kg of body mass) during 14 days after birth. During the period from 1 up to 6 months of life in intact rats a decrease in C-cells functional activity is observed. Under conditions of sympathectomy in 30-day-old animals decreasing extrusion processes of the secretory material are observed. During successive periods of life (3 and 6 months) mechanisms of paracrinic evacuation of hormonal products enhance considerably, nuclear volume of the cells and number of C-cells in the field of vision increase. Their hyperplastic alterations in the sympathectomized thyroid gland are more pronounced in 3-month-old animals.     

Protoplast Formation of the Coccolithophorid <Emphasis Type="Italic">Pleurochrysis haptonemofera</Emphasis> in Hypoosmotic K<Superscript>+</Superscript> Solution: Shedding of the Coccosphere and Regrowth of the Protoplast in Normal Medium

Both coccolith-bearing cells (C-cells) and naked cells (N-cells) of the coccolithophorid Pleurochrysis haptonemofera can grow in salinities of more than 7‰ (about 20% of a “normal” sea water salinity [35‰]), with the highest growth rates in salinities of more than 14‰. Microscopic observations of cells suspended in 100 mM NaCl (7‰) showed that, while N-cells were swelling uniformly all over the cell surface, C-cells were bulging the plasma membrane from the hole of the coccosphere at the apical (flagellar) pole of the cell. Effects of several cations and anions on the morphological change of C-cells under hypoosmotic pressure were investigated. When 100 mM K⁺ was used, protoplasts were released from the coccosphere completely in almost all the cells. This phenomenon was shown with K⁺ most effectively. The protoplasts could grow in the fresh medium and form the first coccolith within 9 h.     

Crystals in sugar beet (<Emphasis Type="Italic">Beta vulgaris</Emphasis> L.) leaves

Crystal-containing cells (C-cells) are widely spread in plant tissues; however, the origin of the crystals and their functions remain a subject of discussion. In sugar beet leaves, the membrane vesicles seen in an electron microscope appear in the cytoplasm and penetrate the vacuole by pinocytosis with the participation of tonoplast. In a light microscope, the vesicles fluoresce like crystals in C-cells. These crystal vesicles also fill the C-cells. The content of crystal vesicles is electron-transparent at all stages of leaf development. It is suggested that both individual crystal vesicles in the cytoplasm and in vacuoles and their agglomerations in C cells, vascular bundles, and epidermal cells are lytic compartments. Later, true crystals seem to be formed.     

Influence of development on the number of calcitonin-containing cells in the mouse thyroid.

Calcitonin-containing cells in serial, 6-micrometer sections of the thyroid glands of Swiss Webster mice, at 1 day, 2 weeks, 4 weeks and 8 weeks of age, were demonstrated by an immunoperoxidase method, using antiserum to human calcitonin. C-cell nuclei were counted in every sixth section of both left and right lobes. The average number of C-cells counted in the thyroid glands of 8-week-old animals was 18-fold, 5.5-fold and 2.5-fold greater than the number observed in 1-day, 2-week and 4-week-old animals, respectively. C-cell concentration was found to be greatest in 4-week-old mice. Mitoses of C-cells were observed in animals which were 1 day, 2 weeks and four weeks old. No mitotic figures were seen in 8-week-old animals. A few C-cells were seen in close association with neurons. The volume of the thyroid glands of 8-week-old animals was about 14-, 4- and 3-fold greater than the volume in the 1-day-old, 2-week-old and 4-week-old mice, respectively. These changes in the C-cell population during development provide a model for the study of C-cell proliferation and storage of calcitonin.