N alpha- and N epsilon-D-galacturonoyl-L-lysine amides: properties and possible occurrence in plant cell walls

Three representatives of a novel class of amide (isopeptide) glycoconjugates have been synthesised: N alpha-D-galacturonoyl-L-lysine and N epsilon-D-galacturonoyl-L-lysine and N epsilon-D-polygalacturonoyl-L-lysine. Galacturonoyl-lysine amide bonds were labile in 2 M trifluoroacetic acid at 120 degrees and in alkali, but relatively stable in cold acid. The amide bonds were resistant to digestion by Driselase, Pronase and trypsin. The polysaccharide backbone of N epsilon-D-polygalacturonoyl-L-lysine was hydrolysed by Driselase to yield two major ninhydrin-positive compounds which were shown by 1H and 13C NMR spectroscopy to be tri- and tetra-alpha-(1-->4)-D-galacturonoyl-L-lysines. To investigate the possible natural occurrence of N-galacturonoyl isopeptide bonds, we fed cell-suspension cultures of spinach and tomato with D-[6-14C]glucuronic acid, which radio-labels pectic polysaccharides. The radioactive cell walls were digested with, sequentially, Driselase, mild acid, and proteinases. On electrophoresis at pH 2.0, several of the radioactive digestion-products were cathodic. Some of the cathodic products yielded [14C]galacturonic acid upon complete acid hydrolysis. The existence of these products is compatible with the presence of novel N-galacturonoyl isopeptide bonds, which could serve as cross-links in plant cell walls.     

Intense muscle uptake of gallium-67 in a patient with sarcoidosis

Sarcoidosis has been associated with muscle involvement. In general, this involvement remains asymptomatic. The following case report demonstrates a patient with a 4-mo history of sarcoidosis who reported severe fatigue and slight muscular complaints at a regular checkup. Gallium scintigraphy indicated unexpected and unusually extensive muscular localizations of the disease. The latter findings were confirmed by examination of biopsy specimens. The importance of gallium scintigraphy lies in the possibility of wholebody screening for inflammation localizations, particularly when physical, laboratory, lung function and radiographic examinations fail to provide convincing evidence of active sarcoidosis. Furthermore, it can be helpful in the follow-up of the effect of supportive treatment.     

P2 receptor-mediated signal transduction in Ehrlich ascites tumor cells

The mechanisms, by which the P2 receptor agonists adenosine 5'-triphosphate (ATP) and uridine 5'-triphosphate (UTP) evoke an increase in the free cytosolic calcium concentration ([Ca2+]i) and in intracellular pH (pHi), have been investigated in Ehrlich ascites tumor cells. The increase in [Ca2+]i evoked by ATP or UTP is abolished after depletion of intracellular Ca2+ stores with thapsigargin in Ca2+-free medium, and is inhibited by U73122, an inhibitor of phospholipase C (PLC), indicating that the increase in [Ca2+]i is primarily due to release from intracellular, Ins(1,4,5)P3-sensitive Ca2+ stores. ATP also activates a capacitative Ca2+-entry pathway. ATP as well as UTP evokes a biphasic change in pHi, consisting of an initial acidification followed by alkalinization. Suramin and 4,4'-diisothiocyano-2,2'-stilbene-disulfonic acid (DIDS) inhibit the biphasic change in pHi, apparently by acting as antagonists at P2 receptors. The alkalinization evoked by the P2 receptor agonists is found to be due to activation of a 5'-(N-ethyl-N-isopropyl)amiloride (EIPA)-sensitive Na+/H+ exchanger. ATP and UTP elicit rapid cell shrinkage, presumably due to activation of Ca2+ sensitive K+ and Cl- efflux pathways. Preventing cell shrinkage, either by incubating the cells at high extracellular K+ concentration, or by adding the K+-channel blocker, charybdotoxin, does not affect the increase in [Ca2+]i, but abolishes the activation of the Na+/H+ exchanger, indicating that activation of the Na+/H+ exchanger is secondary to the Ca2+-induced cell shrinkage.     

Immunology of papillomavirus infection

Studies of the immunology of papillomavirus infection have come of age. Synthetic virus-like particles have been validated as vaccines for several animal papillomaviruses, and have been used to map the sero-epidemiology of human papillomavirus infection and to define papillomavirus neutralizing antibodies. Induction of cell-mediated immunity to papillomavirus early proteins is poised to become a therapeutic approach to papillomavirus infection. Studies on the immune response to papillomavirus proteins in keratinocytes are shedding light on the immunological consequences of antigen presentation by epithelial cells.     

Acute ischaemic lesions in death due to ischaemic heart disease. An autopsy study of 333 cases of out-of-hospital death

The frequency of acute coronary artery thrombus and myocardial infarction in subjects dying suddenly or unexpectedly from ischaemic heart disease (IHD) is still unclear, with previous autopsy studies reporting an incidence between 4% and 100%. In this study of 333 randomly selected out-of-hospital deaths, detailed autopsy showed IHD as the sole cause of death in 206 (62%). One hundred and seventeen acute coronary thrombi were present in 96 cases whilst four had an established acute infarct without an identifiable coronary thrombus. Thus 100 (48.5%) IHD deaths had evidence of an acute ischaemic lesion. Acute lesions were equally prevalent among males and females, but the incidence declined with increasing age and they were less frequent among those with a prior clinical history of heart disease. One hundred and forty-seven IHD deaths were witnessed. The proportion of cases with an acute ischaemic lesion increased with the duration of pre-morbid symptoms. Of those with an acute lesion, only 17% died without symptoms compared to 63% of those without an acute lesion. All cases with symptoms lasting more than 3.5 h had an acute lesion. Overall, almost half out-of-hospital IHD deaths in this study were related to an acute ischaemic lesion. Differences in the detail of the pathological examination and examination of differing sub-groups of the out-of-hospital death population probably account for the differing results of previous studies.     

Climate change and the incidence of food poisoning in England and Wales

A study was undertaken to determine the susceptibility or resistance of 9 outbred experimental or commercial poultry lines to Salmonella enteritidis PT4. Young chicks were inoculated either intramuscularly or orally just after hatching. After intramuscular challenge the lines could be divided into susceptible lines (LD 50% < or = 10(2) Salmonella per animal), intermediate lines (LD 50% about 10(4) Salmonella) and resistant lines (LD 50% > 10(5) Salmonella). The results obtained after oral challenge confirmed these 3 groups for both mortality rates and the probability of the presence of salmonellae in the spleen and liver. There was no difference between lines concerning caecal carriage.     

Private practitioners in the slums of Karachi: what quality of care do they offer?

Private health services have expanded in many developing countries over the last 10 yr. Qualified private practitioners provide basic health care for poorer groups in urban areas, although health care planners frequently criticize them for providing poor quality of care, charging high fees and failing to provide preventive health advice. In Karachi, a large city with more than 400 slums, private practitioners are important providers of care to the poor. This study assessed the nature and quality of care provided by 201 practitioners selected from four districts of the city. Vignettes of specific medical problems were used to assess their knowledge and their practice was measured by observing 658 doctor-patient contacts. The results show that knowledge was closer to accepted medical management than was their actual prescribing practice. On the other hand, their manners and interpersonal behaviour were good. Thus poor prescribing practice, which might equally stem from market influences as lack of knowledge, is the cause of low standards of care. In these circumstances, didactic in-service training to improve prescribing practice is unlikely to be successful.