Biomechanical model of human cornea based on stromal microstructure.

The optical characteristics of the human cornea depends on the mechanical balance between the intra-ocular pressure and intrinsic tissue stiffness. A wide range of ophthalmic surgical procedures alter corneal biomechanics to induce local or global curvature changes for the correction of visual acuity. Due to the large number of surgical interventions performed every day, a deeper understanding of corneal biomechanics is needed to improve the safety of these procedures and medical devices. The aim of this study is to propose a biomechanical model of the human cornea, based on stromal microstructure. The constitutive mechanical law includes collagen fiber distribution based on X-ray scattering analysis, collagen cross-linking, and fiber uncrimping. Our results showed that the proposed model reproduced inflation and extensiometry experimental data [Elsheikh et al., Curr. Eye Res., 2007; Elsheikh et al., Exp. Eye Res., 2008] successfully. The mechanical properties obtained for different age groups demonstrated an increase in collagen cross-linking for older specimens. In future work such a model could be used to simulate non-symmetric interventions, and provide better surgical planning.

Human papillomavirus status in advanced cervical cancer: predictive and prognostic significance for curative radiation treatment.

Human papillomavirus (HPV) infection plays a major role in oncogenesis of squamous cell carcinoma of the cervix. This study was performed to investigate if HPV status and E2 gene integrity are prognostic parameters for clinical outcome and predictive for radiation response. Forty women with locally advanced cervical cancer treated with curative radiotherapy were analyzed for HPV infection and E2 gene integrity by multiplex polymerase chain reaction. Statistical analyses were performed for overall survival, disease-free survival (DFS), local progression-free survival, and treatment response (clinical complete remission). Twenty-eight (70%) of 40 carcinomas were HPV positive. The only significant factor for a better overall survival, DFS, and local progression-free survival was HPV positivity (P < 0.02, P= 0.02, and P < 0.05, log-rank, respectively). HPV-positive tumors had a significantly better clinical complete remission (67% vs 33%, P= 0.04, Fisher's exact test). An intact E2 gene region showed a trend for a better DFS (P= 0.1, log-rank). This study reveals HPV as an independent prognostic parameter for outcome and radiation response. Integration of the virus genome into host cell DNA might be a molecular target to determine the treatment response of HPV-positive cancers.

Nodular goiter and goiter nodules: Where iodine deficiency falls short of explaining the facts.

While the concept of iodine deficiency (ID) still dominates most discussions about the pathogenesis of multinodular goiter (MNG), the present review focuses on those mechanisms that may cause MNG in the absence of ID. Among the many facets of MNG that cannot simply be explained by ID, are the frequent occurrence of the disease in patients not exposed to ID, the autonomous growth of goiters - often accompanied by subclinical or even overt thyrotoxicosis -, the inverse relationship between goiter size and serum TSH, the multifocal, heterogeneous and nodular growth pattern, the heterogeneity of function with the familiar patchy iodine metabolism on scintiscans, the growth of clonal and polyclonal nodules, the prominent genetic predisposition. Even the notoriously low intrathyroidal iodine concentration - common to endemic as well as to sporadic goiter - is a secondary, rather than a primary event. Thus, the fundamental process of goitrogenesis, is independent from ID but operates through mechanisms innate to the hereditary and acquired heterogeneity among the thyrocytes themselves. In this view, goiter nodules and nodular goiters are true benign neoplasias arising by mechanisms common to all benign endocrine and nonendocrine neoplasms. However, superimposed iodine shortage greatly enhances the incidence of MNG and shifts its clinical appearance toward younger ages by adding one more growth factor - presumably enhanced TSH secretion - to an intrinsically activated growth regulating network.

Multinodular goitre: 'much more to it than simply iodine deficiency'.

For over a century, multinodular goitre (MNG) has been looked upon as the simple consequence of iodine deficiency. This view is now no longer tenable. Indeed, many characteristics of MNG do not fit with the iodine deficiency concept. For example, nodular goitre is a frequent disease even in those countries where the population is never exposed to iodine shortage. Moreover, neither multinodularity, nor the proverbial heterogeneity of growth and function or the autonomous, thyroid stimulating hormone (TSH)-independent growth of many goitres are compatible with the iodine deficiency concept, let alone subclinical or overt thyrotoxicosis which often complicates the course of a MNG. Recent investigations have led to the conclusion that MNGs are true benign neoplasias that are due to the high intrinsic growth potential of a variable, genetically predetermined fraction of all thyrocytes. Gross and heritable metabolic and functional differences between the individual thyrocytes, from which new follicles are generated during goitrogenesis, are the cause of the often spectacular functional and structural heterogeneity of MNG. Superimposed iodine deficiency changes the epidemiology, but not the basic mechanisms of goitrogenesis. These new pathogenetic concepts have a profound impact on the clinical management of MNG.

Expression of transforming growth factor beta1, beta2, and beta3 in multinodular goiters and differentiated thyroid carcinomas: a comparative study.

The various isoforms of transforming growth factor-beta (TGFbeta) are growth-inhibiting cytokines for cells of epithelial origin. In malignant thyroid tumors, several studies documented a high expression of TGFbeta in the majority of thyroid follicular cells suggesting a possible role as an inhibitor of cell proliferation. In contrast to this uniform pattern of TGFbeta expression in thyroid cancer, scarce and controversial data have been reported on the expression of TGFbeta in benign multinodular goiter. In the present study, we therefore analyzed the expression of TGFbeta1, TGFbeta2, and TGFbeta3 in normal thyroid tissue, multinodular goiters and papillary thyroid carcinomas by immunohistochemistry. In normal thyroid tissue, expression of the 3 TGFbeta isoforms was barely detectable. However, in the carcinomas, almost all epithelial cells displayed immunoreactivity for the three TGFbeta isoforms. In the nodules from multinodular goiters, all 3 isoforms were found to be expressed although the immunolocalization of the 3 proteins was highly variable. TGFbeta-immunostaining was found in scattered clusters of variable size and, its expression pattern was heterogenous among individual cells within single follicles. TGFbeta-positivity was present in spite of immunostaining for proliferating cell nuclear antigen (PCNA), a marker for actively proliferating cells. In conclusion, this study shows that thyroid carcinomas and benign tumors express the TGFbeta1, TGFbeta2, and TGFbeta3 isoforms. In contrast to the abundant and homogeneous expression in differentiated thyroid carcinomas, TGFbeta expression displays a highly variable interfollicular and intrafollicular pattern in multinodular goiters, suggesting an important role of TGFbeta isoforms in tumorigenesis of thyroid cells.

[A quality culture for health promotion!]. / Eine Qualitätskultur für die Gesundheitsförderung!

Quality and quality management are omnipresent as notions in the daily life of projects but there exists neither a clear conception nor a homogeneous quality understanding. This expresses the fact that a critical and self-reflecting project culture is not rooted strongly enough. A good project and quality management is indispensable to optimize the goal attainment. Up to now, however, concrete implementations as far as quality improvement in the daily lift of projects is concerned, were lacking. This article shows the necessity of health promotion being confronted with quality and what can be gained by that. It presents a project of the Institute of Social and Preventive Medicine of the University of Zurich in which quality promotion is specifically put into practice. In co-operation with project leaders, instruments for a quality management are being developed and tested which support and steer the constant process of quality promotion.

Acquired and naturally occurring resistance of thyroid follicular cells to the growth inhibitory action of transforming growth factor-beta 1 (TGF-beta 1).

While the multifunctional proteins of the transforming growth factor-beta (TGF-beta) family have a potent antiproliferative effect on thyroid follicular cell growth, increased expression of TGF-beta in proliferating thyroid cells and in thyroid tumours has recently been described, suggesting a secondary counter-regulatory role of these proteins. We have studied further this apparent paradox in vitro using FRTL-5 cells, 5 continuous cell strains from feline multinodular goitres (MNG) and 29 primary cultures prepared from human MNG. While dose dependent inhibition of FRTL-5 cell growth was confirmed, a variable fraction of these cells was naturally resistant towards TGF-beta 1, thus explaining the large interassay variability of growth inhibition (36 to 98% within 2 days, n = 19). After 40 days of continuous exposure, FRTL-5 cells became fully refractory towards TGF-beta 1 inhibition, due to the selective growth of naturally resistant subclones, as demonstrated for example by microscopic observation of three-dimensionally growing collagen-embedded cell clusters. The refractoriness could still be demonstrated even after several cell passages. In addition, 2 out of 5 feline thyroid cell strains obtained from feline MNG and 18 out of 29 primary cultures from human MNG showed a high degree of refractoriness towards TGF-beta. We conclude that constitutively TGF-beta resistant cells may occur in thyroid glands and that persistent TGF-beta refractoriness may secondarily be acquired. Resistant cells may escape regular growth control mechanisms and hence may contribute to the notorious heterogeneity of thyroid growth and to nodular transformation.

Mechanisms of nonneoplastic endocrine hyperplasia--a changing concept: a review focused on the thyroid gland.

An important part of clinical endocrinology deals with diseases caused by benign and malignant nodules growing within originally homogeneous endocrine glands. In the search for the pathogenesis of these nodules, two concepts have been advanced: either the hyperplastic tissue is considered to result from chronic intense stimulation by a trophic hormone, eventually causing the growth of polyclonal nodules (a concept known as NNEH) or else, the nodules are thought to represent true clonal tumors. It has been realized rather recently that NNEH accounts only for a small minority of rare endocrine diseases, with the exception of highly prevalent iodine deficiency goiters and, in a broader sense, for Graves' disease. Indeed, secondary hyperplasia of endocrine glands resulting from long-lasting chronic hormonal overstimulation cannot explain a large number of essential features of the diseased glands. As best documented for the thyroid gland, outstanding among the characteristics of hyperplastic glands that do not fit into the simple concept of NNEH are the inevitable nodular transformation, the frequent autonomy and irreversibility of nodular growth, the loss of function in many cells and nodules, and the tremendous regional heterogeneity of growth and function including loss of coordination between these two main features of any living cell. Hyperplasia resulting from long-lasting stimulation by a trophic hormone is not a fully reversible process, as is often thought, but definitely increases the total cell mass and leaves behind, after cessation of the stimulus, a population of newly generated cells. This process is common to NNEH and true neoplastic growth. A review of common and disparate traits between endocrine hyperplasia and neoplasia must be based on the following generally accepted facts (excluding in-depth consideration of malignancy). 1. Many endocrine tumors are clonal while others are polyclonal. For example, pituitary and sporadic parathyroid adenomas are nearly always clonal while in the thyroid, multiple clonal nodules of different origin may coexist with polyclonal nodules. 2. Clonal growth does not necessarily indicate that the autonomous expansion of a tumor is driven by presently known genetic gain-of-function or loss-of-inhibition mutations or by cytogenetic aberrations. 3. Genetic mutations and chromosomal aberration in endocrine tumors are not necessarily primary events in the tumorigenesis but may as well be a late secondary phenomenon in growing tissue. 4. Clonal nodules may overgrow from primarily polyclonal ones. The best evidence to date comes from the rare clonal parathyroid adenomas with allelic loss of chromosome 11 evolving in tertiary hyperparathyroidism.(ABSTRACT TRUNCATED AT 400 WORDS)

[Goiter: from epiphenomenon of iodine deficiency to benign tumor. A 30-year long guided story]. / Der Kropf: vom Epiphänomen des Jodmangels zum benignen Tumor. Eine 30 Jahre lang begleitete Geschichte.

Thirty years ago, iodine deficiency was highly prevalent in Switzerland and, consequently, few people doubted that shortage of this element fully accounted for the very high incidence of nodular goiters. Most research efforts were aimed at unraveling the mechanisms that allowed the thyroid to maintain adequate hormone production - at the expense of goiter formation - despite insufficient iodine supply. In 1982 iodine deficiency was eradicated in this country, a remarkable achievement of preventive medicine. Although the incidence of goiter dramatically decreased thereafter, this thyroid disease has remained and still is a common problem. Only now has it become clear that factors other than or in addition to iodine shortage must be operative in goitrogenesis and that classical features, such as the tremendous functional and morphological heterogeneity of goitrous tissue, and, in particular, the growth of nodules, must result from causes and mechanisms that are common to the pathological growth of other tissues too. Subsequently, the thyroid has become a rewarding source of information about cellular and - more recently - molecular events that accompany and might possibly cause pathological growth. Today, thyroid nodules are considered to be true monoclonal and polyclonal tumors. Hence, we no longer wonder why eradication of iodine shortage cannot totally prevent or reverse goiter growth. - While modern molecular biology unravels - at an amazing pace - the mechanisms that cause heterogeneity between individuals of a single species, goitrogenesis offers a unique opportunity to go one step beyond, which is the inborn and acquired heterogeneity between the individual cells of the same tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidermal growth factor stimulates cell proliferation and inhibits iodide uptake of FRTL-5 cells in vitro.

In accordance with the available data most authors conclude that epidermal growth factor (EGF) has very little or no effect on FRTL-5 cells. This has been viewed as a serious handicap of this cell line. In the present study we cultivated three strains of FRTL-5 cells from different sources and assessed their response to EGF with regard to proliferation, function and differentiation. Cell proliferation was assessed by counting in a Coulter cell counter after culturing cells at suboptimal conditions in well plates. Cell function was studied by measuring iodide uptake. Cell differentiation was examined immunocytochemically by staining monolayer cultures for thyroglobulin (Tg) and EGF receptor (EGFr) as well as morphologically by microscopical evaluation of monolayer cultures. All three FRTL-5 cell lines investigated express EGFr. In two wild type FRTL-5 cell lines EGF stimulates growth, an effect that is enhanced by the presence of TSH, and partially inhibits iodide uptake. A third mutated strain of FRTL-5 cells does not respond to EGF. Tg expression can be demonstrated immunocytochemically in EGF-treated cells as well as in controls. Morphologically, in monolayer culture EGF-treated cells cannot be distinguished from controls. Contrary to previous reports, these studies demonstrate EGF effects on FRTL-5 cells that are consistent with EGF effects established in other thyroid follicular cells.

Expression of functional stimulatory guanine nucleotide binding protein in nonfunctioning thyroid adenomas is not correlated to adenylate cyclase activity and growth of these tumors.

In thyroid cells, the alpha-subunit of the stimulatory guanine nucleotide binding protein (Gs alpha) acts as signal transducer between the TSH receptor and the adenylate cyclase (AC), and it regulates both growth and function. In order to analyze Gs alpha expression by both Western blot analysis and in situ, we generated an antibody raised against a recombinant human Gs alpha protein. With this antibody, a strong cytoplasmic Gs alpha-immunostaining was detectable in cultured human thyroid cells and in TSH-stimulated rat thyroids, in contrast to normal human thyroids and to T4-treated rat thyroids, which showed only weak immunoreactivity. We obtained the following results by immunohistochemistry and Western blot analysis of 32 actively growing human thyroid adenomas: 1) strong Gs alpha expression in 11 adenomas, including 4 hyperfunctioning nodules, 1 of these with a point mutation in codon 201 of the Gs alpha gene; 2) no expression or only weak Gs alpha expression in 13 adenomas; and 3) a pattern of Gs alpha-positive and Gs alpha-negative cells in the remaining 8 adenomas. In addition, we analyzed ADP-ribosylation of Gs alpha and AC activity in 9 nonfunctioning adenomas and found a significant correlation between Gs alpha immunoreactivity and ADP-ribosylation and no correlation of both with basal and TSH-stimulated AC activity. In both types of adenomas, i.e. those with high as well as low Gs alpha, an indistinguishably high fraction of proliferating cells was detectable. We conclude that expression of functional Gs alpha protein in nonfunctioning thyroid adenomas is neither correlated to the basal or TSH-stimulated AC activity nor to the proliferation rate of these tumors.

Polyclonal and monoclonal thyroid nodules coexist within human multinodular goiters.

Although somatic mutations have been identified in a subset of thyroid nodules, the pathogenesis of nodules in multinodular goiters remains unclear. Clonal analysis indicates whether a nodule arises from the polyclonal proliferation of a group of cells or forms a clone from a genetically altered cell. Individual thyroid nodules have been shown to be of polyclonal or monoclonal origin. In this study we examined the clonality of several different nodules in patients with multinodular goiters. Clonality was established using the X-chromosomal probe M27 beta, which detects a multiallelic polymorphism at the locus DXS255 in 90% of females. Twenty-five nodules from 9 multinodular goiters were analyzed; 9 nodules were polyclonal, and 16 were monoclonal. Three goiters contained only polyclonal nodules, whereas 3 contained only monoclonal nodules. Polyclonal and monoclonal nodules coexisted in 3 goiters. In 2 goiters, the monoclonal nodules were shown to derive from different progenitor cells. We conclude that polyclonal and monoclonal nodules may coexist in multinodular goiters and that monoclonal nodules can originate from different cells. The coexistence of polyclonal and monoclonal nodules suggests that different pathogenic mechanisms occur simultaneously or that monoclonal nodules emerge secondarily from a polyclonal population due to a growth advantage from a genetically altered cell.

The degree of inhibition of thyroid follicular cell proliferation by iodide is a highly individual characteristic of each cell and differs profoundly in vitro and in vivo.

Pharmacological concentrations of iodide (> 1 x 10(-6) mol/l) are known to inhibit thyroid follicular cell growth in vitro. However, the inhibitory effect varies widely, depending on experimental conditions, and usually does not exceed 50%. We demonstrate that iodide (10(-4) mol/l) inhibits the growth of FRTL-5 cells in different passages by 11-67%. When five subclones of FRTL-5 cells were compared to the wild type, iodide-induced growth inhibition varied between 25% and 46%. The individual degree of inhibition of each clone was reproducible in two subsequent passages, suggesting that it is a stable constitutive trait. When FRTL-5 cells were grown first in three-dimensional clusters and then transplanted onto nude mice with high endogenous thyrotropin secretion, iodide at a serum concentration of less than 5.7 x 10(-7) mol/l nearly completely blocked cell replication in the transplants but not in the mice's own thyroid. Five cell lines, prepared from autonomously growing hyperthyroid feline multinodular goiters, were nearly completely resistant to the growth-inhibitory effect of iodide. These observations suggest that the sensitivity towards the growth-inhibiting effect of iodide is a highly variable, stable trait of each thyrocyte, even in cloned cell populations. Some FRTL-5 cells and, even more so, cells prepared from autonomously growing nodular feline goiters are resistant constitutively to the growth-inhibiting effect of iodide.(ABSTRACT TRUNCATED AT 250 WORDS)

Low intrathyroidal iodine concentration in non-endemic human goitres: a consequence rather than a cause of autonomous goitre growth.

Iodine may have an inhibitory and, in some circumstances, a stimulatory effect on thyroid follicular cell growth. Exogenous iodine deficiency causes the growth of endemic goitres and it has been claimed that low intrathyroidal iodine stores stimulate growth. On the other hand, the role of iodine, if any, in regulating the growth of human nodular goitres exposed to an ample supply of iodine has not been studied systematically. Very few data on intrathyroidal iodine concentration in this type of goitre are available. In the present work we have investigated total iodine content in 24 samples from 11 clinically and histomorphologically well-defined fast and autonomously growing human nodular goitres from a non-endemic area. Iodine was fractionated into thyroglobulin-iodine and non-thyroglobulin-iodine. The regional distribution of intrathyroidal iodo-compounds was also assessed in three goitres. Total iodine concentration, as well as its sub-fractions, i.e. thyroglobulin-iodine and non-thyroglobulin-iodine, were significantly lower than in normal thyroids. Furthermore, there was large inter- and intraindividual heterogeneity of all iodo-compounds as well as of thyroglobulin. Total iodine concentration varied by a factor of almost 40 between different goitre samples and by a factor of 20 between samples taken from the same goitre. Total non-thyroglobulin-iodine, the only fraction comprising possible cell growth-regulating iodo-compounds, varied by a factor of > 60 between different goitres and by a factor of > 6 between different samples of the same goitre. The low iodine concentration in all our goitre samples did not differ from values reported in the literature for endemic iodine-deficient goitres. Since all goitres studied here were actively growing while exposed to an ample supply of iodine, iodine shortage cannot be a primary and causal factor for the growth of this type of sporadic goitre. Rather, the low concentration and the large inter- and intraindividual heterogeneity of all iodo-compounds appear to be secondary incidental events well explained by the recently developed concept of autonomous thyroid growth.

The effect of prednisolone and a protein-deficient diet on plasma albumin and fibrinogen in a turpentine-induced acute-phase reaction in rats.

The acute-phase reaction (APR) that follows inflammation is characterized by profound metabolic changes such as hypoalbuminemia, which is frequently aggravated by malnutrition; and hyperfibrinogenemia. Because some of these changes are mediated by cytokines, corticosteroids that are known to suppress cytokine production might be expected to alleviate the course of the APR. In the present study, for 3 weeks rats were fed (1) a standard diet (25%) protein), (2) a protein-deficient diet (5% protein), or (3) a standard diet supplemented by treatment with intraperitoneal prednisolone (7.5 mg twice daily starting 3 days before and throughout the experiment). Changes in plasma albumin, fibrinogen, and total protein levels were measured 0, 1, 3, and 8 days after turpentine was injected subcutaneously. Albumin and fibrinogen were immunohistochemically stained in the liver 0, 3, and 8 days after injection. Plasma albumin decreased by roughly 50% in all three groups, and reached a nadir on day 3. Fibrinogen peaked by day 1 in all animals and fell gradually thereafter. The total protein concentration, which was higher with prednisolone, remained unchanged in all three groups. The level of immunostainable liver albumin was initially reduced in malnourished rats. If further diminished in the majority of hepatocytes after administration of turpentine in all groups. Although few hepatocytes stained positive for fibrinogen before the onset of inflammation, uniform increase in immunostaining occurred by day 3 in all rats regardless of treatment. Neither prednisolone nor malnutrition substantially altered the decrease in plasma albumin and the simultaneous increase in fibrinogen in a turpentine-induced APR.(ABSTRACT TRUNCATED AT 250 WORDS)