Dentists' opinions of their dental education; results of a survey of dentists who studied in Amsterdam between the years 1982-1990

Four hundred and fifty dental graduates from the Free University (VU), the University of Amsterdam (UvA) or the Academic Center for Dentistry Amsterdam (ACTA) between 1982 and 1990 were asked by questionnaire to give their opinion about the undergraduate dental training they received. Most respondents felt that their undergraduate education prepared them reasonably well for general practice. Yet imperfections in the education were noticed. These imperfections show resemblance to conclusions from similar surveys in other countries.     

Requirement for tumor necrosis factor receptor 2 expression on vascular cells to induce experimental cerebral malaria

Using tumor necrosis factor receptor type 2 (TNFR2)-deficient mice and generating bone marrow chimeras which express TNFR2 on either hematopoietic or nonhematopoietic cells, we demonstrated the requirement for TNFR2 expression on tissue cells to induce lethal cerebral malaria. Thus, TNFR2 on the brain vasculature mediates tumor necrosis factor-induced neurovascular lesions in experimental cerebral malaria.     

Human TLR-7-, -8-, and -9-mediated induction of IFN-alpha/beta and -lambda Is IRAK-4 dependent and redundant for protective immunity to viruses

Five TLRs are thought to play an important role in antiviral immunity, sensing viral products and inducing IFN-alpha/beta and -lambda. Surprisingly, patients with a defect of IRAK-4, a critical kinase downstream from TLRs, are resistant to common viruses. We show here that IFN-alpha/beta and -lambda induction via TLR-7, TLR-8, and TLR-9 was abolished in IRAK-4-deficient blood cells. In contrast, IFN-alpha/beta and -lambda were induced normally by TLR-3 and TLR-4 agonists. Moreover, IFN-beta and -lambda were normally induced by TLR-3 agonists and viruses in IRAK-4-deficient fibroblasts. We further show that IFN-alpha/beta and -lambda production in response to 9 of 11 viruses tested was normal or weakly affected in IRAK-4-deficient blood cells. Thus, IRAK-4-deficient patients may control viral infections by TLR-3- and TLR-4-dependent and/or TLR-independent production of IFNs. The TLR-7-, TLR-8-, and TLR-9-dependent induction of IFN-alpha/beta and -lambda is strictly IRAK-4 dependent and paradoxically redundant for protective immunity to most viruses in humans.     

Studies on intracellular transport of secretory proteins in the rat exocrine pancreas

Summary The possible role of microtubules and microfilaments in the secretory process of the rat exocrine pancreas was analysed in vitro using isolated pancreatic lobules. Colchicine and vinblastine as microtubule inhibitors, hexylene glycol as a microtubule stabilizer, and cytochalasin B as a disruptive agent for microfilaments were used in increasing concentrations to test their effects on protein synthesis, intracellular transport, zymogen discharge, and cellular respiration.Colchicine only at 10^–2 M concentrations inhibits protein synthesis, while vinblastine inhibits at 10^–6 and 10^–5 M by 20% and at 10^–4 M by 55%. A similar inhibition is observed with 1.5% concentrations of hexylene glycol while cytochalasine B at 1,5 and 10 g/ml is without effect on protein synthesis. Colchicine and vinblastine have their major effects on intracellular transport both in secretion studies and cell fractionation experiments. Colchicine in concentrations between 10^–3 to 10^–5 M inhibits discharge of newly synthesized proteins by 50%, while vinblastine shows a dose-response relationship of 40% inhibition at 10^–6 M to 90% at 10^–4 M. Discharge of amylase is uniformly reduced by 30% by both colchicine and vinblastine in the whole dose range. The pronounced effect of colchicine and vinblastine is evident in cell fractionation studies: both drugs inhibit the disappearance of protein radioactivity from microsomes and its appearance in zymogen granules; similarly the peak radioactivity in smooth microsomes (Golgi) appears delayed. No differential effect on the secretory process was observed with 1.5% concentrations of hexylene glycol or cytochalasin B at 1.5 and 10 g/ml concentrations. A fines tructural analysis of microtubules and microfilaments in the exocrine pancreatic cell reveals their distribution in all parts of the cytoplasm and in relation to all cell organelles. Both systems (microtubules, microfilaments) seem to be connected, at least in certain areas of the cytoplasm and at the plasma membrane.The reduction of transport efficiency by microtubule inhibitors results in a deposition of secretory material in the cisternal space of the rough endoplasmatic reticulum, which leads to the formation of paracrystals. Colchicine at 10^–3 M concentrations leads to an enlargement of condensing vacuoles in the Golgi complex.A short communication on the same subject was presented at a Symposion on Stimulus-Secretion-Coupling in the Gastro-intestinal Tract, Titisee (May 27–29, 1975).Supported by Deutsche Forschungsgemeinschaft (Ke 113/8).     

Die sogenannte Impfwut

Zusammenfassung Die im Verlaufe antirabischer Vaccinationen gelegentlich auftretenden paralytischen Komplikationen sind nicht virusbedingt, sondern die Folge einer Antigen-Antikörperreaktion nach Sensibilisierung mit dem organspezifischen Hirnantigen, das in den nicht ätherisierten Tollwutvaccinen enthalten ist. Diesbezüglich von einer Impfwut zu sprechen, erscheint nicht gerechtfertigt. Vielmehr sollte dieser Terminus für die postvaccinalen Komplikationen reserviert bleiben, bei denen der Ausbruch der Erkrankung in direktem Kausalzusammenhang zu dem in einer Vaccine enthaltenen lebenden Virus fixe steht.     

Noninvasive measurement of cell volume changes by negative staining

To maintain the intracellular concentration of ions and small molecules on osmotic challenges, nature has developed highly sophisticated transport systems for regulating water and ion content. An ideal measurement technique for volume changes of cells during osmotic challenges has to fulfil two requirements: it has to be osmotically inert, and it should allow online monitoring of cell volume changes. Here, a simple fluorescence microscopy-based approach is presented. Using fluorescein as a negative stain, it is possible to monitor cell volume changes without affecting the functionality of cell membranes and cell osmolarity. Measurement of Madine-Darby canine kidney (MDCK) cells after hypo- and hyperosmotic challenges reveals the main advantages of this approach: besides providing precise and reproducible quantitative data on reversible cell volume changes, the viability of the cells can be assessed directly by the appearance of stain in the cytoplasm. This becomes evident especially after hypo-osmotic challenge of glutaraldehyde-treated cells, which become leaky after fixation, followed by a massive volume change. This new approach represents a very sensitive measurement technique for cell volume changes resulting from water or ion flux, and thus seems to be an ideal tool for studying cell volume regulatory processes.     

The homogeneous photopolymerization of methyl methacrylate by colloidal cadmium sulfide

A completely new method of initiating the homogeneous radical polymerization of methyl methacrylate in bulk or in solution via the photogeneration of an electron hole pair in colloidal cadmium sulfide is presented. A polymerization mechanism involving an excited cadmium sulfide particle in both the initiation and termination steps is proposed. In the initiation a methyl methacrylate molecule is oxidized by a positive hole photogenerated in a CdS particle, which results in a novel chain-end structure of the poly(methyl methacrylate) (PMMA). Degradative chain transfer to reduced excited cadmium sulfide particles is responsible for chain termination. Thus, for the first time, a detailed polymerization mechanism in which all states of the polymerization, i.e., initiation, propagation, chain transfer and termination, is presented for the polymerization of vinyl monomers initiated by semiconductors. Thermogravimetry (TG) showed that the newly synthesized PMMA has greatly enhanced thermal stability when compared to normal radically prepared PMMA. In fact, the thermal stability approaches that of anionically prepared PMMA but is experimentally much easier to prepare. This technique enables the homogeneous embedding of CdS particles in a polymer matrix.     

Biochemical investigation with regard to infection and immunity of Eimeria acervulina in the fowl

Summary Biochemical investigation of the fluid surrounding the sporocysts in the oocysts (oocyst fluid) showed the presence of the common amino acids, -isoaminobutyric acid, glycerol, an unidentified carbohydrate and proteins.Incubation experiments with D-glucose-¹⁴C (U) revealed the presence of enzymes able to convert glucose into lactic acid and other acids. Inside the sporocysts the common amino acids, glycerol and the unidentified carbohydrate were also present, but -isoaminobutyric acid did not occur. The carbohydrate binding protein carboglutelin, carbohydrate phosphate and small amounts of glucose and fructose were mainly found inside the sporocysts.Incubation experiments of oocyst fluid mixed with sporocysts with D-glucose-C¹⁴ (U) demonstrated an interchange between the fluid and the sporocysts. In the oocyst fluid lactic acid was formed, but inside the sporocysts the conversion appeared to stop mainly with formation of carbohydrate phosphate.Incubation experiments of intestinal pieces both from immunized and not-immunized birds with oocyst fluid, sporocysts and labelled glucose showed that a stronger reaction took place in immunized birds than in not-immunized ones.Similar experiments were performed with not-immunized birds at different days after a primary infection. The reaction of the intestinal wall, which seemed quite normal again since day 19 after infection, was comparable with that observed in immunized birds.Finally the hypothesis is given, that in the first part of the intestine of immunized birds compounds are present originating from the first infection. These compounds might enhance the reaction between the oocyst fluid and the present feed to such an extent that the pH decreases and much epithelial cells are pushed off possibly together with the sporocysts. Then leakage of serum proteins might occur.     

Interventions to Increase Multivitamin Use Among Women in the Interconception Period: An IMPLICIT Network Study

Maternal and Child Health Journal - Each year, 3% of infants in the Unites States (US) are born with congenital anomalies, including 3000 with neural tube defects. Multivitamins (MVIs) including...