Prevalence of plaque, gingivitis and caries in 11-12-year-old children in South Wales

The overall eruption and dental disease status of a group of 1015 11-12-yr-old schoolchildren in South Wales is presented. The mean number of teeth erupted was 21.8 with a distribution pattern reflecting continuing eruption of teeth at this age. Almost equal numbers of contralateral and opposing tooth types were present with exceptions including maxillary canines and lateral incisors. DMFT, DMFS, and DFS scores were consistent with other recent studies. The mean plaque score was 2.44 and showed a normal distribution for the group. All children had gingivitis at one or more sites as evidenced by bleeding on probing, and again the distribution pattern was a normal one. The mean pocketing was 1.24 mm and there was little clinical evidence of chronic periodontitis. As expected, plaque and gingivitis showed a very high and significant correlation, with plaque and pocketing and gingivitis and pocketing having lower correlation coefficients which were nevertheless highly significant.

On the preparation of cryosections for immunocytochemistry

The key preparation steps in the Tokuyasu thawed frozen section technique for immunocytochemistry, namely freezing, sectioning, thawing, and drying, were studied. A spherical tissue culture cell was used as a model system. The frozen hydrated section technique indicated that glutaraldehyde-fixed, 2.1 M sucrose-infused pellets of cells were routinely vitrified by immersion in liquid nitrogen but water was crystallized when lower sucrose concentrations (0.6-1 M) were used. Quantitative mass measurements showed that the fixed cells are freely permeable to sucrose. The frozen hydrated sections were severely compressed but cell profiles regained their circular appearance upon thawing. The average section thickness of our frozen-hydrated sections was 110 nm: this was reduced to 30-50 nm upon thawing, washing, and air-drying. This change was accompanied by severe drying artifacts. By using the methyl cellulose drying technique, this collapse upon air-drying could be significantly reduced, but not completely prevented, giving an average thickness of 70 nm.

Newly synthesized G protein of vesicular stomatitis virus is not transported to the Golgi complex in mitotic cells

Newly synthesized G protein of vesicular stomatitis virus is not transported to the surface of cultured mammalian cells during mitosis (Warren et al., 1983, J. Cell Biol. 97:1623-1628). To determine where intracellular transport is inhibited, we have examined the post-translational modifications of G protein, which are indicators of specific compartments on the transport pathway. G protein in mitotic cells had only endo H-sensitive oligosaccharides containing seven or eight mannose residues, but no terminal glucose, and was not fatty acylated. These modifications were indicative of processing only by enzymes of the endoplasmic reticulum (ER). Quantitative immunocytochemistry was used as an independent method to confirm that transport of G protein out of the ER was inhibited. The density of G protein in the ER cisternae was 2.5 times greater than in infected G1 cells treated similarly. Incubation of infected mitotic cells with cycloheximide, which inhibits protein synthesis without affecting transport, did not result in a decrease in the density of G protein in the ER cisternae, demonstrating that G protein cannot be chased out of the ER. These results suggest that intracellular transport stops at or before the first vesicle-mediated step on the pathway.

Exit of newly synthesized membrane proteins from the trans cisterna of the Golgi complex to the plasma membrane

The intracellular location at which the G protein of vesicular stomatitis virus accumulated when transport was blocked at 20 degrees C has been studied by biochemical, cytochemical, and immunocytochemical methods. Our results indicated that the viral G protein was blocked in that cisterna of the Golgi stack which stained for acid phosphatase. At 20 degrees C this trans cisterna became structurally altered by the accumulation of G protein. This alteration was characterized by extensive areas of membrane buds which were covered by a cytoplasmic coat. These coated structures were of two kinds--those that labeled with anti-clathrin antibodies and those that did not. The clathrin-coated pits consistently did not label with anti-G antibodies. Upon warming infected cells to 32 degrees C, G protein appeared on the surface within minutes. Concomitantly, the trans cisterna lost its characteristic structural organization. Double-labeling experiments were performed in which G protein localization was combined with staining for horseradish peroxidase, which had been taken up from the extracellular medium by endocytosis. The results suggest that the trans cisterna was distinct from the endosome compartment and that the latter was not an obligatory station in the route taken by G protein to the cell surface.

The acylation of sn-glycerol 3-phosphate and the metabolism of phosphatidate in microsomal preparations from the developing cotyledons of safflower (Carthamus tinctorius L.) seed

Microsomal preparations from the developing cotyledons of safflower (Carthamus tinctorius) catalysed the acylation of sn-glycerol 3-phosphate in the presence of acyl-CoA. The resulting phosphatidate was further utilized in the synthesis of diacyl- and tri-acylglycerol by the reactions of the so-called 'Kennedy pathway' [Kennedy (1961) Fed. Proc. Fed. Am. Soc. Exp. Biol. 20, 934-940]. Diacylglycerol equilibrated with the phosphatidylcholine pool when glycerol backbone, with the associated acyl groups, flowed from phosphatidate to triacylglycerol. The formation of diacylglycerol from phosphatidate through the action of a phosphatidate phosphohydrolase (phosphatidase) was substantially inhibited by EDTA and, under these conditions, phosphatidate accumulated in the microsomal membranes. The inhibition of the phosphatidase by EDTA was alleviated by Mg2+. The presence of Mg2+ in all incubation mixtures stimulated quite considerably the synthesis of triacylglycerol in vitro. Microsomal preparations incubated with acyl-CoA, sn-glycerol 3-phosphate and EDTA synthesized sufficient phosphatidate for the reliable analysis of its intramolecular fatty acid distribution. In the presence of mixed acyl-CoA substrates the sn-glycerol 3-phosphate was acylated exclusively in position 1 with the saturated fatty acids, palmitate and stearate. The polyunsaturated fatty acid linoleate was, however, utilized largely in the acylation of position 2 of sn-glycerol 3-phosphate. The affinity of the enzymes involved in the acylation of positions 1 and 2 of sn-glycerol 3-phosphate for specific species of acyl-CoA therefore governs the non-random distribution of the different acyl groups in the seed triacylglycerols. The acylation of sn-glycerol 3-phosphate in position 1 with saturated acyl components also accounts for the presence of these groups in position 1 of sn-phosphatidylcholine through the equilibration of diacylglycerol with the phosphatidylcholine pool, which occurs when phosphatidate is utilized in the synthesis of triacylglycerol. These results add further credence to our previous proposals for the regulation of the acyl quality of the triacylglycerols that accumulate in developing oil seeds [Stymne & Stobart (1984) Biochem. J. 220, 481-488; Stobart & Stymne (1985) Planta 163, 119-125].

Restriction of docking protein to the rough endoplasmic reticulum: immunocytochemical localization in rat liver

Docking protein (or SRP receptor) is an integral membrane protein essential for translocation of nascent polypeptides across the membrane of the endoplasmic reticulum (ER). Anti-docking protein antibodies were used to localize this protein in situ in thin frozen sections using protein A-gold detection methods. The majority of gold particles was restricted to ribosome-studded membranes, whereas particles were rarely seen in areas rich in smooth ER. Quantitative evaluation of labeling suggests that there is one molecule of docking protein for roughly 10 to 20 bound ribosomes. On the basis of these results we conclude that docking protein is the first functionally-characterized integral marker protein specific for the rough membranes of ER.

Density of newly synthesized plasma membrane proteins in intracellular membranes II. Biochemical studies

Using two independent methods, incorporation of radioactive amino-acid and quantitative immunoblotting, we have determined that the rate of synthesis of each of the Semliki Forest virus (SFV) proteins in infected baby hamster kidney (BHK) cells is 1.2 X 10(5) copies/cell/min. Given the absolute surface areas of the endoplasmic reticulum and Golgi complex presented in the companion paper (Griffiths, G., G. Warren, P. Quinn , O. Mathieu - Costello , and A. Hoppeler , 1984, J. Cell Biol. 98:2133-2141), and the approximate time spent in these organelles during their passage to the plasma membrane (Green J., G. Griffiths, D. Louvard , P. Quinn , and G. Warren 1981, J. Mol. Biol. 152:663-698), the mean density of each viral protein in these organelles can be calculated to be 90 and 750 molecules/micron 2 membrane, respectively. In contrast, we have determined that the density of total endogenous integral membrane proteins in these organelles is approximately 30,000 molecules/micron 2 so that the spike proteins constitute only 0.28 and 2.3% of total membrane protein in the endoplasmic reticulum and Golgi, respectively. Quantitative immunoblotting was used to give direct estimates of the concentrations of one of the viral membrane protein precursors (E1) in subcellular fractions; these agreed closely with the calculated values. The data are discussed with respect to the sorting of transported proteins from those endogenous to the intracellular membranes.

Density of newly synthesized plasma membrane proteins in intracellular membranes. I. Stereological studies

As the spike proteins of Semliki Forest virus (SFV) pass from their site of synthesis in the endoplasmic reticulum (ER) to the cell surface, they must be concentrated and freed from endogenous proteins. To determine the magnitude of this sorting process we have measured the density of spike proteins in membranes of the intracellular transport pathway. In this first paper, using stereological procedures, we have estimated the surface areas of the ER, Golgi complex, and plasma membrane of infected and mock-infected baby hamster kidney cells. First, we estimated the mean cell volume in absolute units. This was done using a novel in situ method which is described in detail. Infection by SFV was found to have no effect on any of the parameters measured. In the accompanying paper ( Quinn , P., G. Griffiths, and G. Warren, 1984, J. Cell Biol., 2142-2147) these stereological estimates were combined with biochemical estimates of the amount of spike proteins in ER, Golgi complex, and plasma membrane to determine the density in the membranes of these compartments.

Reproducibility of an index for recording the alignment of individual teeth

In order that relationships between dental irregularities and the caries and periodontal status of individual teeth can be examined, the STRAIT index (standardized technique for recording the alignment of individual teeth) was developed. Tooth position scores representing vertical relationship, rotation, mesio-distal inclination, displacement and radial relationship are recorded using three- or five-category scales. Contact point scores representing bucco-lingual and mesio-distal relationships are measured directly. These characteristics are recorded for each tooth in the dentition, together with overjet and overbite measures for maxillary incisors and canines. Repeat measurement of 50 sets of models was undertaken by two examiners in order to assess intra-and interreproducibility of the index. A formula for adjusted agreement was employed for analysis of the categorized variables, and reproducibility was typically 80 per cent or better. Analysis of the reproducibility of the continuous variables was based on calculation of root mean square values of the difference between data sets and t-tests. In the main, intra- and interreproducibility was within 0.5 mm. These levels of accuracy meet the requirements of the index and it has since been used in an investigation of 1000 subjects.

Newly synthesized G protein of vesicular stomatitis virus is not transported to the cell surface during mitosis

Indirect immunofluorescence, immunoelectron microscopy, and digestion by protease were used to study intracellular transport of the G protein of vesicular stomatitis virus in mitotic and interphase cells. Quantitation showed that the appearance of G protein on the surface of mitotic cells was inhibited at least 10-fold when compared with that on interphase cells, even though similar amounts of viral protein were being synthesized. This dramatic inhibition, taken together with the simultaneous inhibition of endocytosis (Berlin, R. D., and J. M. Oliver, 1980, J. Cell Biol. 85: 660-671), points to a general cessation of membrane traffic in the mitotic cell.

Viral glycoproteins at different stages of intracellular transport can be distinguished using monoclonal antibodies

Monoclonal antibodies were raised against Semliki Forest virus (SFV) and all were found to recognize the E2 spike glycoprotein. The hybridomas were screened by immunofluorescence microscopy of infected cells to look for antibodies recognizing E2 at different stages of intracellular transport and two (9AB4 and 9AD6) were chosen for further study. Immunocytochemical studies at the light and electron microscopic levels were used to show that 9AB4 recognized E2 at all stages of its transport from the rough endoplasmic reticulum (ER), where it was synthesized, to the cell surface via the smooth ER and Golgi complex. In contrast, 9AD6 only recognized E2 once it had left the ER and entered the stacks of flattened Golgi cisternae. Binding of 9AD6 to E2 did not appear to be the result of the changes in oligosaccharide structure that occur in the Golgi complex and the precise modification detected by 9AD6 remains to be elucidated. A later modification, the cleavage of precursor E2 (p62) to give mature E2, was used to show that 9AD6 bound the latter more tightly than the former, whereas 9AB4 bound both with equal affinity. These results show that monoclonal antibodies might be useful when searching for new modifications to proteins undergoing intracellular transport.

Dissection of the Golgi complex. II. Density separation of specific Golgi functions in virally infected cells treated with monensin

In the accompanying paper (Griffiths, G., P. Quinn, and G. Warren, 1983, J. Cell Biol., 96:835-850), we suggested that the Golgi stack could be divided into functionally distinct cis, medial, and trans compartments, each comprising one or two adjacent cisternae. These compartments were identified using Baby hamster kidney (BHK) cells infected with Semliki Forest virus (SFV) and treated with monensin. This drug blocked intracellular transport but not synthesis of the viral membrane proteins that were shown to accumulate in the medial cisternae. In consequence, these cisternae bound nucleocapsids. Here we show that this binding markedly increased the density of the medial cisternae and allowed us to separate them from cis and trans Golgi cisternae. A number of criteria were used to show that the intracellular capsid-binding membranes (ICBMs) observed in vivo were the same as those membranes sedimenting to a higher density in sucrose gradients in vitro, and this separation of cisternae was then used to investigate the distribution, within the Golgi stack, of some specific Golgi functions. After labeling for 2.5 min with [3H]palmitate, most of the fatty acid attached to viral membrane proteins was found in the ICBM fraction. Because the viral membrane proteins appear to move from cis to trans, this suggests that fatty acylation occurs in the cis or medial Golgi cisternae. In contrast, the distribution of alpha 1-2-mannosidase, an enzyme involved in trimming high-mannose oligosaccharides, and of galactosyl transferase, which is involved in the construction of complex oligosaccharides, was not affected by monensin treatment. Together with data in the accompanying paper, this would restrict these two Golgi functions to the trans cisternae. Our data strongly support the view that Golgi functions have specific and discrete locations within the Golgi stack.

Dissection of the Golgi complex. I. Monensin inhibits the transport of viral membrane proteins from medial to trans Golgi cisternae in baby hamster kidney cells infected with Semliki Forest virus

Baby hamster kidney (BHK) cells were infected with Semliki Forest virus (SFV) and, 2 h later, were treated for 4 h with 10 microM monensin. Each of the four to six flattened cisternae in the Golgi stack became swollen and separated from the others. Intracellular transport of the viral membrane proteins was almost completely inhibited, but their synthesis continued and they accumulated in the swollen Golgi cisternae before the monensin block. In consequence, these cisternae bound large numbers of viral nucleocapsids and were easily distinguished from other swollen cisternae such as those after the block. These intracellular capsid-binding membranes (ICBMs) were not stained by cytochemical markers for endoplasmic reticulum (ER) (glucose-6-phosphatase) or trans Golgi cisternae (thiamine pyrophosphatase, acid phosphatase) but were labeled by Ricinus communis agglutinin I (RCA) in thin, frozen sections. Since this lectin labels only Golgi cisternae in the middle and on the trans side of the stack (Griffiths, G., R. Brands, B. Burke, D. Louvard, and G. Warren, 1982, J. Cell Biol., 95:781-792), we conclude that ICBMs are derived from Golgi cisternae in the middle of the stack, which we term medial cisternae. The overall movement of viral membrane proteins appears to be from cis to trans Golgi cisternae (see reference above), so monensin would block movement from medial to the trans cisternae. It also blocked the trimming of the high-mannose oligosaccharides bound to the viral membrane proteins and their conversion to complex oligosaccharides. These functions presumably reside in trans Golgi cisternae. This is supported by data in the accompanying paper, in which we also show that fatty acids are covalently attached to the viral membrane proteins in the cis or medial cisternae. We suggest that the Golgi stack can be divided into three functionally distinct compartments, each comprising one or two cisternae. The viral membrane proteins, after leaving the ER, would all pass in sequence from the cis to the medial to the trans compartment.

Viral membrane proteins acquire galactose in trans Golgi cisternae during intracellular transport

Frozen, thin sections of baby hamster kidney (BHK) cells were incubated with either concanavalin A (Con A) or Ricinus communis agglutinin I (RCA) to localize specific oligosaccharide moieties in endoplasmic reticulum (ER) and Golgi membranes. These lectins were then visualized using an anti-lectin antibody followed by protein A conjugated to colloidal gold. All Golgi cisternae and all ER membranes were uniformly labeled by Con A. In contrast, RCA gave a uniform labeling of only half to three-quarters of those cisternae on the trans side of the Golgi stack; one or two cis Golgi cisternae and all ER membranes were essentially unlabeled. This pattern of lectin labeling was not affected by infection of the cells with Semliki Forest virus (SFV). Infected cells transport only viral spike glycoproteins from their site of synthesis in the ER to the cell surface via the stacks of Golgi cisternae where many of the simple oligosaccharids on the spike proteins are converted to complex ones (Green, J., G. Griffiths, D. Louvard, P. Quinn, and G. Warren. 1981. J. Mol. Biol. 152:663-698). It is these complex oligosaccharides that were shown, by immunoblotting experiments, to be specifically recognized by RCA. Loss of spike proteins from Golgi cisternae after cycloheximide treatment (Green et al.) was accompanied by a 50% decrease in the level of RCA binding. Hence, about half of the RCA bound to Golgi membranes in thin sections was bound to spike proteins bearing complex oligosaccharides and these were restricted to the trans part of the Golgi stack. Our results strongly suggest that complex oligosaccharides are constructed in trans Golgi cisternae and that the overall movement of spike proteins is from the cis to the trans side of the Golgi stack.

A monoclonal antibody against a 135-K Golgi membrane protein

A monoclonal antibody ( 53FC3 ) has been produced against a Golgi membrane protein with a mol. wt. of 135 000 which was originally identified using a polyclonal antiserum. Treatment of isolated, intact Golgi vesicles with protease caused a decrease in mol. wt. of 5000-10 000, whereas in the presence of Triton X-100, the protein was completely degraded. This shows that the protein spans the bilayer and that most of its mass is on the luminal side of Golgi membranes. Using two immunoelectron microscopic techniques, the protein was found in one or two cisternae on one side of the Golgi stack which, in normal rat kidney cells, had 4-6 cisternae. As an illustration of the use to which this monoclonal antibody can be put we present a light microscopic study of the disassembly and reassembly of the Golgi complex during mitosis.

Demonstration of myoglobin in formalin-fixed renal sections by immunoperoxidase technic

The use of an immunohistochemical technic offers a very sensitive method to detect myoglobin in formalin-fixed, paraffin-embedded tissues. Thus, the technic is suitable for retrospective studies. Myoglobin can be demonstrated at the brush border and apical cytoplasm of the tubular epithelium of proximal tubules. Granular substances and casts in the lumens also react positively with antimyoglobin. Our findings confirm the results of a previous animal study, showing that myoglobin is filtered through glomeruli and reabsorbed by the proximal tubules.