Stress changes of the wrist in adolescent gymnasts

The radiographic appearances are reported of chronic stress to the wrist joints of eight adolescent males, seven gymnasts and one roller skater. These consist of bilateral, asymmetrical widening and irregularity of the distal radial growth plates with an ill-defined cystic appearance, sclerosis and flaring of the metaphyses in all eight cases. Similar but less marked changes were present in the distal ulnar growth plates in five cases. The aetiology is thought to be that of a Salter Type I stress fracture of the growth plate due to chronic repetitive shear forces applied to the hyperextended wrist joint. Rapid healing of the stress fracture will occur with cessation of the sporting activity but continued strenuous use of the wrists will result in further widening and irregularity of the growth plate. The differential diagnosis of the radiographic appearances and previous literature are discussed.

Enzymatic sulphation of mucus glycoprotein in rat sublingual salivary gland

Sulphotransferase activity catalysing the transfer of sulphate ester group from 3'-phosphoadenosine-5'-phosphosulphate to salivary mucus glycoprotein was located in detergent extracts of the Golgi-rich membrane fraction of rat sublingual salivary glands. Optimum enzyme activity was obtained with 0.5 per cent Triton X-100, 20 mM NaF and 2 mM MgCl2, at pH 6.8, using desulphated sublingual salivary mucus glycoprotein. The enzyme was equally capable of sulphation of the proteolytically degraded and desulphated glycoprotein, whereas the acceptor capacity of intact salivary mucus glycoprotein was about four times lower. The Golgi enzyme preparation also catalysed the sulphation of galactosylceramide. However, the sulphation of mucus glycoprotein was not affected by the presence of this glycolipid, suggesting that the sulphotransferase involved in mucin sulphation is different from that responsible for the synthesis of galactosylceramide sulphate. The apparent Km of the sublingual-gland mucus glycoprotein sulphotransferase for salivary mucin was 7.7 microM. The 35S-labelled glycoprotein product of the enzyme reaction gave, in CsCl density gradient, a band in which the 35S label coincided with the glycoprotein. Alkaline borohydride reductive cleavage of this glycoprotein released the label into the reduced acidic oligosaccharide fraction. Upon thin-layer chromatography, two [35S]-oligosaccharides were detected. These were identified as penta- and heptasaccharides, each bearing a labelled sulphate ester group on the terminal N-acetylglucosamine residue. Based on the results of chemical and enzymatic analyses of the intact and desulphated compounds the following structures for these oligosaccharides are suggested: SO3----GlcNAc beta----Gal beta----GlcNAc beta----Gal beta----GlcNAc beta----(NeuAc----)GalNAc-ol and SO3----GlcNAc beta----Gal beta----GlcNAc beta----(NeuAc----)GalNAc-ol.

Paradoxical effects of thought suppression

In a first experiment, subjects verbalizing the stream of consciousness for a 5-min period were asked to try not to think of a white bear, but to ring a bell in case they did. As indicated both by mentions and by bell rings, they were unable to suppress the thought as instructed. On being asked after this suppression task to think about the white bear for a 5-min period, these subjects showed significantly more tokens of thought about the bear than did subjects who were asked to think about a white bear from the outset. These observations suggest that attempted thought suppression has paradoxical effects as a self-control strategy, perhaps even producing the very obsession or preoccupation that it is directed against. A second experiment replicated these findings and showed that subjects given a specific thought to use as a distracter during suppression were less likely to exhibit later preoccupation with the thought to be suppressed.

Enzymatic sulfation of mucin in gastric mucosa: effect of sofalcone, sucralfate and aspirin

A sulfotransferase activity which catalyzes the transfer of a sulfate group from 3'-phosphoadenosine-5'-phosphosulfate to gastric mucus glycoprotein has been demonstrated in the rat gastric mucosa. Subcellular fractionation studies revealed that the enzyme activity was present in a Golgi-rich membrane fraction. Optimum enzymatic activity for sulfation of mucus glycoprotein was obtained with 0.5% Triton X-100 and 30 mM NaF at a pH of 6.8. The apparent Km of the enzyme for gastric mucus glycoprotein was 10.5 microM, and the sulfate ester was found incorporated into the carbohydrate chains of mucin. The sulfo-transferase activity of the Golgi enzyme was stimulated by sofalcone, while reduction in the rate of sulfation occurred in the presence of sucralfate and aspirin. The rate of enhancement of mucin sulfation by sofalcone was proportional to the drug concentration up to 5 X 10(-7) M, at which concentration a 17% increase in the glycoprotein sulfation was attained. The rate of inhibition of mucin sulfation was proportional to concentrations of aspirin up to 3 X 10(-4) M and of sucralfate up to 1 X 10(-4) M, at which concentrations about 50% reduction in sulfotransferase activity was obtained. The apparent KI values calculated from the double-reciprocal plots were 15.1 microM for aspirin and 19.6 microM for sucralfate. The results suggest that although both sucralfate and sofalcone are potent gastric mucosal strengthening agents, only sofalcone is capable of enhancement of the sulfotransferase enzyme involved in gastric mucin sulfation.

Intestinal release of mucin in response to HCl and taurocholate: effect of indomethacin

1. Alkaline secretion and mucin output were analyzed along the gastrointestinal tract of a dog in response to luminal application of HCl and taurocholate with and without pretreatment with indomethacin. 2. Mucins derived from the different areas displayed similar contents of protein and carbohydrate but differed with respect to associated and covalently bound lipids. 3. Application of HCl or taurocholate in all the regions caused an increase in the output of mucins and HCO3-. However, mucins elaborated in response to HCl exhibited higher total lipid content and were richer in phospholipids. 4. Pretreatment with indomethacin prior to HCl application led to a reduction in HCO3- and caused a decrease in mucin phospholipid content, but had no effect on HCO3- secretion and the lipid content of mucins elaborated in response to taurocholate. 5. The results indicate that mucins elaborated along the gastrointestinal tract differ with respect to lipids, and that their output in response to HCl is mediated by prostaglandins.

Paradoxical effects of thought suppression

In a first experiment, subjects verbalizing the stream of consciousness for a 5-min period were asked to try not to think of a white bear, but to ring a bell in case they did. As indicated both by mentions and by bell rings, they were unable to suppress the thought as instructed. On being asked after this suppression task to think about the white bear for a 5-min period, these subjects showed significantly more tokens of thought about the bear than did subjects who were asked to think about a white bear from the outset. These observations suggest that attempted thought suppression has paradoxical effects as a self-control strategy, perhaps even producing the very obsession or preoccupation that it is directed against. A second experiment replicated these findings and showed that subjects given a specific thought to use as a distracter during suppression were less likely to exhibit later preoccupation with the thought to be suppressed.

Mucus glycoprotein secretion by duodenal mucosa in response to luminal arachidonic acid

The effect of luminal application of arachidonic acid on the alkaline secretion, prostaglandin generation, and mucus glycoprotein output and composition was studied in proximal and distal duodenum of conscious dogs. Surgically prepared duodenal loops were instilled in vivo for up to 2 h with saline (control) followed by various concentrations (12.5-100 micrograms/ml) of arachidonic acid. The experiments were conducted with and without intravenous pretreatment with indomethacin. The recovered instillates were assayed for the content of prostaglandin and HCO3-, and used for the isolation of mucus glycoprotein. Exposure of duodenal mucosa to arachidonic acid led to concentration-dependent increase in the output of HCO3- and prostaglandin generation. In both cases this response was greater in the proximal duodenum. Pretreatment with indomethacin caused reduction in the basal HCO3- and prostaglandin output, and prevented the increments evoked by arachidonic acid. The proximal and distal duodenum displayed similar basal output and composition of mucus glycoprotein. Comparable increases in these glycoproteins were also obtained with arachidonic acid, the effect of which was abolished by indomethacin. Compared to basal conditions, mucus glycoproteins elaborated in response to arachidonic acid exhibited higher contents of associated lipids and covalently bound fatty acids, and contained less protein. The associated lipids of mucus glycoproteins elaborated in the presence of arachidonic acid showed enrichment in phospholipids and decrease in neutral lipids. The carbohydrate components in these glycoproteins also exhibited higher proportions of sialic acid and sulfate. The changes brought about by arachidonic acid were prevented by indomethacin pretreatment, and in both cases the glycoprotein composition returned to that obtained under basal conditions. The enrichment of mucus glycoprotein in lipids, sialic acid and sulfate in response to endogenous prostaglandin may be of significance to the function of this glycoprotein in the hostile environment of the duodenum.

Effect of covalently bound fatty acids and associated lipids on the viscosity of gastric mucus glycoprotein in cystic fibrosis

The contribution of associated and covalently bound lipids to the viscosity of gastric mucus glycoprotein in healthy and cystic fibrosis (CF) individuals was investigated. While both preparations exhibited similar contents of protein and carbohydrate, the CF glycoprotein contained 1.3 times more associated lipids and 6 times more covalently bound fatty acids. The viscosity of CF mucus glycoprotein was about 1.8 times higher than that of normal glycoprotein. Extraction of associated lipids lead to 3-fold drop in the viscosity of CF glycoprotein and 5-fold drop in the case of normal glycoprotein. Removal of covalently bound fatty acids caused further 1.6-fold reduction in the viscosity of normal mucus glycoprotein and 6-fold in CF glycoprotein. The viscosity of the delipidated and deacylated CF mucus glycoprotein was only about 10% higher than that of the similarly treated normal glycoprotein. The results suggest that the elevated level of covalently bound and associated lipids is responsible for the increased viscosity of CF mucin.

Enzymic acylation of mucus glycoprotein with palmitic acid in rat submandibular salivary gland

The enzymic activity which catalyses transfer of palmitic acid from palmitoyl coenzyme A to mucus glycoprotein was found in Triton X-100 extracts of the microsomal fraction of rat submandibular and sublingual salivary glands. The acyltransferase activity of this fraction was 1.3-1.4 times greater in submandibular gland than in sublingual gland. Further subcellular fractionation of submandibular gland showed that the enzyme activity was associated with a Golgi-rich membrane fraction. Optimum enzyme activity for fatty acylation of mucus glycoprotein was at pH 7.4 using 0.5 per cent Triton X-100, 2 mM dithiothreitol 25 mM NaF and 10 mM MgCl2; higher concentrations were inhibitory. The apparent Km of the submandibular microsomal enzyme for mucus glycoprotein was 5.9 X 10(-7) M, and for palmitoyl-CoA, 3.3 X 10(-5) M. The 14C-labelled glycoprotein product of the reaction co-migrated on CsCl equilibrium, density-gradient centrifugation with submandibular mucus glycoprotein, and contained ester-bound palmitic acid. The fatty acyltransferase showed no activity with proteolytically-degraded glycoprotein; the acceptor capacity of reduced and S-carboxymethylated glycoprotein was only about 10 per cent lower than that of the intact mucus glycoprotein. This suggests that the acylation of salivary mucus glycoprotein with fatty acids occurs at its non-glycosylated, proteolysis-susceptible regions, and that the majority of these fatty acids are linked to the glycoprotein through hydroxyl esters.

Mucus glycoprotein fatty acyltransferase in patients with cystic fibrosis: effect on the glycoprotein viscosity

The presence of an acyltransferase activity which catalyzes the transfer of palmitic acid from palmitoyl coenzyme A to mucus glycoprotein has been demonstrated in the microsomal fraction of human rectal mucosa. The activity of this enzyme in the mucosa of patients with cystic fibrosis (CF) was found to be 3.5 times higher than that from normal individuals. The CF mucus glycoprotein in comparison to that of normal contained 1.3 times more associated lipids and 6 times more covalently bound fatty acids. The viscosity of the intact CF glycoprotein was 1.8 times higher than that of normal glycoprotein. Extraction of associated lipids led to 3-fold drop in the viscosity of CF glycoprotein and 5-fold drop in the case of normal glycoprotein. Further loss in the viscosity occurred following removal of the covalently bound fatty acids. The viscosity of such modified CF mucus glycoprotein was only about 10% higher than that of similarly treated normal glycoprotein.

Neodymium and Strontium Isotope Evidence for Crustal Contamination of Continental Volcanics

Combined neodymium and strontium isotope studies on Tertiary volcanics from northwest Scotland indicate that their parental mantle isotopic compositions have been substantially modified in many instances by contamination with the Precambrian continental crust through which they were erupted. The occurrence of samarium-neodymium and rubidium-strontium "pseudoisochrons" of different ages in these contaminated continental volcanics indicates that they are artifacts of the contamination processes and have no temporal significance with respect to mantle fractionation events.