Plasticity of Dental Cell Types in Development, Regeneration, and Evolution.

Recent years have improved our understanding of the plasticity of cell types behind inducing, building, and maintaining different types of teeth. The latest efforts were aided by progress in single-cell transcriptomics, which helped to define not only cell states with mathematical precision but also transitions between them. This includes new aspects of dental epithelial and mesenchymal stem cell niches and beyond. These recent efforts revealed continuous and fluid trajectories connecting cell states during dental development and exposed the natural plasticity of tooth-building progenitors. Such "developmental" plasticity seems to be employed for organizing stem cell niches in adult continuously growing teeth. Furthermore, transitions between mature cell types elicited by trauma might represent a replay of embryonic continuous cell states. Alternatively, they could constitute transitions that evolved de novo, not known from the developmental paradigm. In this review, we discuss and exemplify how dental cell types exhibit plasticity during dynamic processes such as development, self-renewal, repair, and dental replacement. Hypothetically, minor plasticity of cell phenotypes and greater plasticity of transitions between cell subtypes might provide a better response to lifetime challenges, such as damage or dental loss. This plasticity might be additionally harnessed by the evolutionary process during the elaboration of dental cell subtypes in different animal lineages. In turn, the diversification of cell subtypes building teeth brings a diversity of their shape, structural properties, and functions.

Asexual queen succession mediates an accelerated colony life cycle in the termite Silvestritermes minutus.

Mixed modes of reproduction, combining sexual processes with thelytokous parthenogenesis, occur in all major clades of social insects. In several species of termites, queens maximize their genetic input into nondispersing replacement queens through parthenogenesis, while maintaining genetically diverse sterile offspring and dispersing reproductives via sexual reproduction. This so-called asexual queen succession (AQS) has multiple independent origins and its presumed advantages are diverse as well, ranging from multiplication of colony reproductive potential to extension of its lifespan beyond that of the foundress. However, how AQS shapes colony life cycles under natural conditions remains poorly known. The neotropical termite Silvestritermes minutus inhabits small but conspicuous nests, offering a unique opportunity to investigate the impact of AQS on life history. We report on its breeding system, life cycle and sex allocation using social structure census in 137 nests and genotyping of 12 colonies at 12 microsatellite loci. We show that colonies are established by an outbred pair of primary reproductives. In less than 2 years, the foundress is replaced by multiple neotenic queens, arising mostly through automixis with central fusion. Sterile castes, male and most (93%) female dispersers are produced sexually. Colony reproduction is usually restricted to a single dispersal of alates with unbiased sex ratio, taking place after 3 years. We conclude that S. minutus benefits from AQS to maximize colony growth rate and alate production within a very short life cycle rather than to extend colony lifespan. This highlights the versatile role of AQS in different cases of its polyphyletic origin.

Three-dimensional Imaging Reveals New Compartments and Structural Adaptations in Odontoblasts.

In organized tissues, the precise geometry and the overall shape are critical for the specialized functions that the cells carry out. Odontoblasts are major matrix-producing cells of the tooth and have also been suggested to participate in sensory transmission. However, refined morphologic data on these important cells are limited, which hampers the analysis and understanding of their cellular functions. We took advantage of fluorescent color-coding genetic tracing to visualize and reconstruct in 3 dimensions single odontoblasts, pulp cells, and their assemblages. Our results show distinct structural features and compartments of odontoblasts at different stages of maturation, with regard to overall cellular shape, formation of the main process, orientation, and matrix deposition. We demonstrate previously unanticipated contacts between the processes of pulp cells and odontoblasts. All reported data are related to mouse incisor tooth. We also show that odontoblasts express TRPM5 and Piezo2 ion channels. Piezo2 is expressed ubiquitously, while TRPM5 is asymmetrically distributed with distinct localization to regions proximal to and within odontoblast processes.

Recent approaches in tooth engineering research.

Tooth absence and defects caused by various reasons are frequent events in humans. They are not life threatening but may bring about social consequences. Recent dentistry provides solutions in the form of prosthetics or dental implants; however, several complications and distinct limitations favour bioengineering of dental and periodontal structures. At least two types of cells (epithelial and mesenchymal) have to be recombined to produce a new functional tooth. Moreover, the tooth must be vascularized, innervated and properly anchored in the bone. To study these issues, different approaches have been established in both basic and applied research. In this review, recent strategies and techniques of tooth engineering are comprehensively summarized and discussed, particularly regarding manipulation using stem cells.

Properties of neural crest-like cells differentiated from human embryonic stem cells.

Neural crest cells (NCCs) derive early in vertebrate ontogenesis from neural tube as a population of migratory cells with exquisite differentiation potential. Abnormalities in NCC behaviour are cause of debilitating diseases including cancers and a spectrum of neurocristopathies. Thanks to their multilineage differentiation capacity NCCs offer a cell source for regenerative medicine. Both these aspects make NCC biology an important issue to study, which can currently be addressed using methodologies based on pluripotent stem cells. Here we contributed to understanding the biology of human NCCs by refining the protocol for differentiation/propagation of NCClike cells from human embryonic stem cells and by characterizing the molecular and functional phenotype of such cells. Most importantly, we improved formulation of media for NCC culture, we found that poly-L-ornithine combined with fibronectin provide good support for NCC growth, we unravelled the tendency of cultured NCCs to maintain heterogeneity of CD271 expression, and we showed that NCCs derived here possess the capacity to react to BMP4 signals by dramatically up-regulating MSX1, which is linked to odontogenesis.

Can adequate treatment influence the postembolization syndrome and cytokine release in patients undergoing iatrogenic renal artery embolization?

The complete renal artery embolization is an alternative to surgical nephrectomy in seriously ill patients. Iatrogenic embolization can be used in many different conditions. Refractory nephrotic syndrome represents a very rare indication for embolization. Complete renal artery embolization has usually been complicated by postembolization syndrome (PES) which is characterized by flank pain and fever. Possible immunologic contribution to the PES leads some authors to the administration of corticosteroids to the patients undergoing embolization. We report here a cohort of 13 patients undergoing complete embolization of total 21 kidneys due to refractory nephrotic syndrome non-responding to the various specific treatment regimes. We treated our patients undergoing renal artery embolization according to special protocol containing combination of antibiotic drugs and corticosteroids (CS) to diminish PES and evaluated its influence to the cytokine production. The incidence of PES was less frequent and milder in comparison with the historical group of patients. Significant decrease in plasma levels of tumor necrosis factor α during first post-embolization day (8.37 pre- vs. 5.74 pg/ml post-embolization, P=0.0002) could partially explain the reduction of PES symptoms. The procedure was not complicated by severe complications and represents an elegant alternative to surgical procedure. The accurate timing of the embolization remains a controversial point in this intervention.

[Pulmonary endarterectomy--the surgical treatment of chronic thromboembolic pulmonary hypertension]. / Endarterektomie plicních tepen--chirurgická lécba chronické tromboembolické plicní hypertenze.

BACKGROUND: Chronic thromboembolic pulmonary hypertension (CTEPH) in indicated cases can be successfully treated by the endarterectomy of pulmonary arteries (PEA). Symptomatically not treated CTEPH has highly unfavourable prognosis. Five years survival of patients with mean pulmonary pressure over 50 mmHg is only 10%. PEA was not available in the Czech Republic till 2004, when PEA program was initiated it the Cardiocenter of the General teaching hospital in Prague in collaboration with leading clinics in that field (Prof. Mayer, University of Mainz, BRD). METHODS AND RESULTS: Up-to-date surgical technique, which in various modifications has been used at majority of clinics, was elaborated by Jamieson and Daily at University of California in San Diego. It is based on reverse endarterectomy performed during complete circulatory arrest with brain protection by deep hypothermia. Till September 2005 twelve patients were operated with zero mortality. In one patient a suture of atrial septum defect was necessary to perform along. Average time of the circulatory arrest was 45 minutes; duration of the extracorporal circulation was 334 minutes. Average duration of the operation was 450 minutes. Duration of the mechanical ventilation was in average 45.5 hours. After one month already haemodynamic parameters (mPA, CI, PVR) significantly improved or normalized and the average length in the test of six minutes walking increased by 132 meters. CONCLUSION: PEA represents a treatment method for patients with CTEPH and surgically accessible pulmonary artery obstruction. Centralized care of those patients is a rational necessity enabling to get maximum experience with complicated diagnostics and treatment of those patients. Multidisciplinary collaboration is the essential condition for the success of the program.

[Embolization of uterine arteries during myoma treatment from the patient's point of view]. / Embolizace delozních tepen pri lécbe myomu z pohledu pacientek.

OBJECTIVES: To acquire information about the patient's follow-up evaluation of treating fibroids by uterine artery embolization (UAE). DESIGN: A retrospective multicenter clinical trial. SETTING: Department of Obstetrics and Gynaecology, 1st Faculty of Medicine and the General Faculty Hospital, Charles University, Prague. METHODS: 45 women who underwent the UAE due to uterine fibroids from 1999 to 2003 were asked to complete a questionnaire. The questionnaire included 26 questions asking how the women had been informed and what they had expected. Further questions were focused on the course of embolization itself, early post-procedural difficulties (post-embolization syndrome) and patient's overall evaluation of treatment in a longer term. Those women who had completed the questionnaire and had been ready to co-operate were thereafter examined and included in the follow-up monitoring and, if necessary, further treatment was recommended. RESULTS: Thirty one out of 45 patients from 26 to 48 years of age, who had been addressed (68.9%) answered the questionnaire. UAE was indicated 12 times (38.7%) on account of symptoms, 10 times (32.3%) because of sterility, 5 times (16.1%) as a preventive measure within the framework of family planning and 4 times (12.9%) for an asymptomatic but growing leiomyoma. Twenty seven (87.1%) women were also offered an alternative treatment, which they refused. As far as problems are concerned, 18 (58%) women described the course of treatment as corresponding with what they had expected, 5 times it was less painful, and 8 times it was worse than expected. The long-term results were considered as positive by 87.1% of responders, only 12.9% considered the treatment as failure. 5 in 11 women planning pregnancy became pregnant, 3 of them gave birth in term and 2 miscarried in the 1st trimester. CONCLUSION: From the point of view of the patients, the evaluated method proves highly successful, it is well tolerated and it involves a low risk of complications. It is not possible, at this point, however, to give an unequivocal answer to the question whether the method should also be routinely offered to women who are planning pregnancy.

[Liver abscesses with portal and mesenteric vein thrombosis in combination with late onset of appendicitis]. / Jaterní abscesy s portální a mezenteriální flebotrombózou v kombinaci s pozdní manifestací apendicitidy.

Pyogenic liver abscesses are caused by appendicitis in less than 10%. Also the ascending septic inflammation of portal vein (pylephlebitis) could be a serious complication of intra-abdominal infection. Although pylephlebitis is not frequent today, its' mortality and morbidity rates remain high. We describe a case of young man with fever, abdominal pain, and multiple hepatic abscesses. After the symptomatic relief due to antibiotic therapy the pain returned as a result of the development of portal and mesenteric vein thrombosis. The cause of either hepatic abscesses or thrombosis was not clear at the time of dismissal. 2 months later the patient underwent acute abdominal revision with appendectomy for acute phlegmonous and gangrenous appendicitis. Since that time he has been without any clinical symptoms.

Conditioned taste aversion and Ca/calmodulin-dependent kinase II in the parabrachial nucleus of rats.

Bielavska and colleagues (Bielavska, Sacchetti, Baldi, & Tassoni, 1999) have recently shown that KN-62, an inhibitor of calcium/calmodulin-dependent kinase II (CaCMK), induces conditioned taste aversion (CTA) when introduced into the parabrachial nucleus (PBN) of rats. The aim of the present report was to assess whether activity of CaCMK in the PBN is changed during CTA. We induced CTA in one group of rats by pairing saccharin consumption with an ip injection of lithium chloride. Another group of rats received lithium alone (without being paired with saccharin consumption) to test whether lithium has an effect on CaCMK in the PBN, independent of those effects due to training. In animals receiving CTA training, CaCMK activity in extracts of PBN was reduced by approximately 30% at the postacquisition intervals of 12, 24, and 48 h, compared to control animals receiving saccharin with saline injection. By 120 h after CTA training, no effect on CaCMK was present. At those postacquisition intervals showing CaCMK activity effects due to CTA, there were no effects attributable to lithium alone. Lithium alone produced only a short-lasting reduction in CaCMK activity (at 20 min a 30% decrease, at 60 min a 23% decrease; and at 6, 12, and 24 h no decrease). The time course of lithium-induced effects differed markedly from that of CTA training. All changes were Ca2+/- -dependent; we did not observe any changes in Ca-independent activity. CTA effects on CaCMK were selective for PBN, insofar as we did not observe any CTA effects on CaCMK in the visual cortex, a brain region unrelated to taste pathways. Since CTA produces a relatively long-lasting reduction in CaCMK activity (lasting 2 days or more) specifically in the PBN, which is critical a relay for taste information, the reduction of CaCMK activity may enable the consolidation of taste memory in an aversive situation.

Dowling-Degos disease--a heat aggravated variant.

A 22-year-old woman presented with a 5-year history of a micropapular eruption localized to the flexor aspect of her limbs as well as persistent reticulate pigmentation of her neck and upper chest resembling Darier's disease. The eruption was associated with pruritus that was precipitated by heat and was worse in summer. The axillae, groins and inframammary areas had multiple papules but lacked reticulate pigmentation. Multiple biopsies showed an epidermis with club- and antler-like rete ridges but no acantholysis or dyskeratosis. This distinct clinical presentation may represent an unusual heat aggravated variant of Dowling-Degos disease that clinically shares features with Darier's disease and transient acantholytic dermatosis.

[Takayasu's disease associated with autoimmune thyroiditis and celiac disease. Clinical course and limitations of treatment]. / Association de la maladie de Takayasu avec la thyroïdite auto-immune et la maladie coeliaque. Déroulement de la maladie et limites du traitment.

Takayasu's arteritis is a non-specific form of vasculitis involving the aorta, its main branches and pulmonary arteries. It is a rare disease in our country, contrasting with the high prevalence in Southeast Asia, Africa and South America. We discuss the course of the disease in our patient who was a young women who developed Takayasu's arteritis associated with autoimmune thyroiditis and malabsorption syndrome due to celiac sprue. Long-term immunosuppressive therapy contributed to stabilizing the associated diseases, but did not stop the progression of the vascular lesions. The main adverse outcome in our patient was the development of severe renovascular hypertension. Bilateral renal artery stenosis was treated by angioplasty with stent implantation. Based on literature reports, the association of Takayasu's disease with multiple autoimmune disorders is a rare event. However, it would appear that the arteritis was the limiting disease for prognosis in our patient.

Glutamate in the parabrachial nucleus of rats during conditioned taste aversion.

Brain microdialysis combined with HPLC and spectroscopic detection was used to monitor extracellular glutamate in the parabrachial nucleus (PBN) of rats during acquisition of a conditioned taste aversion (CTA). Microdialysis fractions taken every 20 min were used to assess the effects of presentation of the conditioned stimulus alone (CS, consumption of 0.1% saccharin), the unconditioned stimulus alone (US, intraperitoneal injection of 0.15 M LiCl, 2% b.w. induced malaise after water drinking) as well as that of CS-US pairing. After 15 min of saccharin drinking, the glutamate concentration in the eluate (20 microl/20 min) reached 80% above the baseline but returned to the basal value in the next fraction. LiCl alone (applied 1 h after 15 min drinking of water) increased glutamate only following some delay, i.e. in the second and third post-lithium fraction by 90 and 67%, respectively. However, when LiCl was injected 1 h after the onset of saccharin intake, the glutamate concentration rose significantly (by 95%) already in the first post-LiCl fraction and by 120% in the second one. It appears, therefore, that the 'saccharin trace' facilitates the effect of lithium on extracellular concentration of glutamate in PBN during acquisition of CTA.

[Incarcerated Waldeyer's hernia as the cause of necrosis of the small intestine (case report)]. / Uskrinutá Waldeyerova kýla jako prícina nekrózy tenkého streva. (Kazuistika).

The authors present a case-record of a rare incarcerated Waldeyer hernia which became the cause of infarsation and necrosis of the free portion of the small intestine in the abdominal cavity, which developed as a result of compression of the upper mesenteric vein by the contents of the hernial sac. The authors draw attention to the asset of CT examination for preoperative diagnosis. US examination failed. They explain why, although a rare acute ileous abdomen is involved, the X-ray picture of levels on the native X-ray of the abdomen is lacking.

Protein kinase C in the parabrachial nucleus of rats during conditioned taste aversion induced by amphetamine.

D-Amphetamine (AM) is a potent inducer of conditioned taste aversion (CTA) the mechanism of which differs from that induced by lithium. The aim of the present communication is to see whether AM-induced CTA will produce shift in the protein kinase (PKC) activity in the parabrachial nucleus (PBN). Activity of PKC was measured in PBN of rats during AM-induced CTA. In the control experiments a single intraperitoneal (i.p.) injection of AM (3 mg/kg) alone (not paired with saccharin drinking) resulted in rise of particulate bound PKC by 77% and a tendency to decrease its activity in cytosol 60 min but not 24 and 48 h after AM administration. The results suggest translocation of the enzyme from cytosol to membrane. Cytosolic PKC increased by 17 and 50%, 24 and 48 h, respectively, after acquisition of CTA (15 min after the retrieval test), when the direct effect of AM on PKC had already disappeared. Particulate PKC did not change at either of the two time intervals. Thus the total PKC activity was increased. Since we have previously observed the same PKC shifts using LiCl or CuSO4 as CTA unconditioned stimuli, we assume that any CTA inducer will elicit the same alteration of PKC in PBN.

[Retrograde intravenous perfusion--a therapeutic method in trophic defects of the lower extremities. Experience in patients with primary thrombocythemia]. / Retrográdní intravenózní perfuze--metoda lécby trofických defektu dolních koncetin. Zkusenosti u pacientu s primární trombocytémií.

Retrograde intravenous perfusion (RIP), so-called Bier's blockade is a relatively new method of treatment of critical ischaemia of the extremities. It is based on the principle of retrograde, i.e. transvenous perfusion of the capillary circulation during which at the time of artificially discontinued circulation in the extremities a high concentration of effective substances in the target tissues is achieved. In addition to the mentioned critical ischaemia Bier's blockade can be successfully used in the treatment of so-called "diabetic foot". It is also possible to implement by this method a local medicamentously induced block of the sympathetic nerves by administration of Guanethidine. In patients with contraindications of systemic fibrinolytic treatment local thrombolysis can be made in phlebothromboses and acral vascular occlusions. In the treatment of tumours on the extremities, e.g. melanoblastome, it is possible to achieve by local administration of cytostatics comparable results, while the incidence of undesirable effects is smaller. The objective of the present work was to make the professional public familiar with this method. On the example of four patients with trophic defects of the lower extremities which developed as a result of primary thrombocythemia the application of Bier's method was demonstrated.

Protein kinase C in the rat cerebral cortex during spreading depression.

Activity and distribution of protein kinase C (PKC) in the rat cerebral cortex was correlated with the development of spreading depression. When the 'waves' of the slow potential shift, induced by topical application of concentrated KCl solutions, were allowed to spread over the cerebral cortex for 10 min, both cytosolic and particulate fractions of the enzyme were increased to 169% and 143%, respectively, of the control values obtained from the contralateral, relatively intact hemicortex. When the enzyme activities were correlated with development of a single slow potential shift, it appeared that in the cortical area fully depolarized (under the maximum of negativity), the respective values were 175% and 157%. One min after recovery of the single wave of spreading depression both cytosolic and particulate fractions continued to rise up to 218% and 239%, respectively. During 5 min of recovery both the cytosolic and particulate fractions fell to 71% and 57%, respectively, of control levels. Even at 10 min the cytosolic enzyme was still decreased to 80%. At 20 min no difference between control and experimental values was found (soluble, 111%; particulate, 96%). The results are discussed in the context of data obtained in a few studies dealing with depolarization-induced changes of PKC in vitro.

Conditioned taste aversion and protein kinase C in the parabrachial nucleus of rats.

The enzymatic activity of protein kinase C (PKC) was measured in the cytosol and particulate fraction of parabrachial nucleus, the presumed site of conditioned taste aversion (CTA) engrams. At various time intervals after acquisition of the task (pairing saccharin consumption with subsequent LiCl poisoning) the nucleus was dissected from the frozen coronal sections. An increase (+40%) in the cytosol PKC activity was found 48 h after that pairing in comparison with controls (saline injection instead of LiCl). Particulate enzyme activity virtual did not change (-5%). Thus the total PKC activity increased significantly (21%). Qualitatively similar but less markedly expressed PKC shifts (+18% in cytosol) ere found 24 h following CTA. Twelve hours and 5 days after CTA acquisition the activity and distribution of PKC was similar to that seen in normal rats. The control experiments revealed that 6 h after LiCl injection alone (without previous saccharin consumption) translocation of PKC from the cytosol to the membrane fraction (found previously 1 h after LiCl injection alone) still persisted but did not differ from that found 6 h after its pairing with saccharin drinking (CTA). It is concluded that acquisition of conditioned taste aversion may be followed by synthesis of PKC rather than by its translocation or downregulation.

GTP, a nonsubstrate of ATP citrate lyase, is a phosphodonor for the enzyme histidine autophosphorylation.

ATP citrate lyase (EC 4.3.1.8.) was shown to be a major phosphorylation protein of a fraction derived from Zajdela rat hepatoma by chromatography on heparin-Ultrogel, after the incubation with [gamma-32P]ATP or [gamma-32P]GTP. Histidine was the only amino acid in the purified enzyme phosphorylated by [gamma-32P]ATP or [gamma-32P]GTP in the autocatalytic reaction which occurred apparently through an intramolecular mechanism regardless of a donor of phosphate. GTP inhibits the ATP-dependent autophosphorylation competitively despite its failure to replace ATP in the formation of acetyl-CoA catalyzed by this enzyme.

[Catheterization therapy of thromboembolic arterial occlusions of the lower extremities]. / Katetrizacní lécba trombembolických uzáveru tepen dolních koncetin.

Thromboembolic occlusions of peripheral arteries may threaten the vitality of extremities and sometimes patients life. Till recently the main therapeutic method was Fogarty surgical thromboembolectomy. A less invasive procedure is systemic (intravenous) and local (intraarterial) thrombolysis. All these method have, however, certain disadvantages. A new approach to the treatment for acute and subacute occlusions of peripheral arteries represents catheter thromboembolectomy, which involves the following: a) Aspiration of thromboembolic material--percutaneous thrombembolextraction (PTEE), b) Local infiltration thrombolysis where the catheter penetrates through the occlusion while simultaneously administering a fibrinolytic agent, c) PTA of residual stenosis in case of thrombotic occlusion. A combination of these methods of treatment for thromboembolic occlusions of peripheral arteries is very effective and enables to use a small amount of thrombolytic agent. The thrombosis and the underlying atherosclerotic stenosis are resolved during the same session.