Lipid peroxidation contributes to hydrogen peroxide induced cytotoxicity in renal epithelial cells

We have examined the role of lipid peroxidation in the cytotoxicity of H2O2 in OK cells containing markedly differing amounts of cell membrane polyunsaturated fatty acids (PUFA). In OK cells grown in a serum free medium, PUFA were undetectable. The membranes of these cells contained predominantly oleic, stearic and palmitic acids. When cultured in medium containing 10% calf serum, OK cells contained measurable amounts of PUFA [linoleic (5 +/- 1%) and arachidonic acids (8 +/- 1%)]. When the serum containing medium was supplemented with 60 mM linoleic acid, the membrane content of both linoleic (21 +/- 1%) as well as arachidonic acid (15 +/- 1%) as substantially increased. The severity of injury induced by H2O2 in OK cells was substantially altered by the PUFA content of the cell membrane. Exposure of OK cells to 1.25 mM H2O2 for one hour resulted in more cell death (determined by a trypan blue assay) in cells grown in serum supplemented with linoleic acid with "normal" PUFA content (90 +/- 2%) than in cells with "reduced" levels of PUFA grown in unsupplemented calf serum (81 +/- 3%). Cells gown in defined, serum free medium with undetectable levels of PUFA suffered the least H2O2-induced lethal cell injury (47 +/- 8%). Comparable differences in the cytotoxicity of H2O2 among cells with differing PUFA content were found using a clonogenic assay of cell viability. Malondialdehyde (MDA) accumulation induced by 1.25 mM H2O2 was greater in cells with "normal" PUFA content (702 +/- 103 pM/microgram cell DNA/hr) than in cells with "reduced" PUFA (328 +/- 112 pM/100 microgram DNA/hr) and was undetectable in cells grown in defined, serum free medium. In summary, the content of PUFA of cells in culture is profoundly influenced by culture conditions. Our data provide novel and direct evidence that peroxidation of cell membranes contributes directly to the severity of cell injury and death induced by H2O2.

Modulation of annexin II tetramer by tyrosine phosphorylation

Annexin II tetramer (AIIt) is a Ca(2+)-dependent phospholipid-binding phosphoprotein. In cells either expressing transforming protein tyrosine kinases or treated with growth factors such as PDGF, AIIt has been shown to contain increased levels of phosphotyrosine. Therefore, we have examined the effects of the in vitro phosphorylation of AIIt by pp60c-src on several activities of the protein. AIIt was phosphorylated by pp60c-src to 0.91 +/- 0.07 mol of phosphate/mol of AIIt (mean +/- SD). The protein tyrosine phosphorylation of AIIt completely inhibited the ability of the protein to bind to and bundle F-actin. In contrast, the phosphoprotein and native protein bound to purified adrenal medulla chromaffin granules with similar affinity; however, the chromaffin granule bridging activity of the phosphoprotein was abolished. The inhibition of the chromaffin granule bridging activity of the phosphoprotein could be partially reversed by the addition of millimolar Ca2+. Furthermore, the phosphorylation of AIIt by pp60c-src inhibited the in vitro ability of this annexin to form a complex consisting of plasma membrane, chromaffin granules, and AIIt. In addition to binding to biological membranes, some annexin proteins have been shown to possess carbohydrate-binding activity. Although native AIIt bound to a heparin affinity column, tyrosine phosphorylation of AIIt blocked the ability of the protein to bind to the heparin affinity column. These results suggest that the tyrosine phosphorylation of AIIt is a negative modulator of AIIt and that the dephosphorylation of AIIt might be necessary for activation of the protein.

Salt dependency of chromaffin granule aggregation by annexin II tetramer

Annexin II tetramer (AIIt) is a Ca2+ and phospholipid binding protein that has been shown to reconstitute secretion in permeabilized adrenal medulla cells. In the present study, we have characterized the interactions of AIIt with biological membranes using isolated adrenal medulla secretory granules as a model system. Without added salt, maximal binding of AIIt to chromaffin granules occurred in the absence of AIIt-dependent chromaffin granule aggregation, whereas increasing the osmolality of the reaction mixture with sucrose did not activate AIIt-dependent chromaffin granule aggregation. As the KCl or potassium glutamate concentration of the reaction mixture was increased to between 30 and 50 mM salt, AIIt-dependent chromaffin granule aggregation increased to a maximum, while AIIt binding to chromaffin granules decreased. As the salt concentration was increased from 50 to 150 mM, both AIIt-dependent chromaffin granule aggregation and the binding of AIIt to chromaffin granules were decreased. Furthermore, at optimal salt concentration, KCl and potassium glutamate activated AIIt-dependent aggregation of chromaffin granules to maximum values of about 210% and 195% of control, respectively, whereas potassium phosphate supported AIIt-dependent aggregation of chromaffin granules to only 120% of control. The concentration of AIIt for half-maximal binding to chromaffin granules without added salt or at 50 mM KCl was 0.163 +/- 0.007 (mean +/- SD, n = 3) or 0.173 +/- 0.034 microM AIIt (mean +/- SD, n = 3), respectively, and binding of AIIt to chromaffin granules was not measurable at 150 mM KCl. In contrast, at 50 mM KCl, half-maximal AIIt-dependent chromaffin granule aggregation required 0.171 +/- 0.001 microM AIIt (mean +/- SD, n = 3) and was not measurable without added salt or in the presence of 150 mM KCl. Without added salt, at 50 mM KCl, or at 150 mM KCl, the Ca2+ concentrations for half-maximal aggregation of chromaffin granules and the maximal extent of chromaffin granule aggregation (Amax) were pCa2+ = 3.79 +/- 0.062 (mean +/- SD, n = 3) and Amax = 127% of control, pCa2+ = 6.07 +/- 0.021 (mean +/- SD, n = 3) and Amax = 185% of control, or pCa2+ 4.41 +/- 0.07 (mean +/- SD, n = 3) and Amax = 156% of control, respectively. The stimulation of chromaffin granule aggregation activity and the chromaffin granule binding activity of AIIt was reversible by removal of Ca2+. These results suggest that both ionic strength and salt composition modulate both AIIt-dependent chromaffin granule aggregation and binding to the membranes of these secretory granules.

Chromaffin granules release calcium on contact with annexin VI: implications for exocytosis

Chromaffin granules represent a substantial and exchangeable intracellular calcium pool which is thought to be regulated by a sodium/calcium exchange protein and also by a putative inositol trisphosphate-activated calcium channel. A family of calcium-binding proteins, called the annexins, has been shown to bind to chromaffin granules. We have therefore investigated the possible involvement of these proteins in the regulation of chromaffin granule sequestered calcium. Annexin VI (A-VI) produced a concentration-dependent release of 45Ca2+ from chromaffin granules; half-maximal release occurred at 1 microM A-VI, with near-maximum release being at 20 microM A-VI. The A-VI-induced release of 45Ca2+ was rapid, being essentially complete by our first time point of 7 s, and corresponded to 40% of the total sequestered 45Ca2+. A-VI-induced release occurred at extravesicular Ca2+ concentrations ranging from a pCa2+ of 4.12 to 6.86 and also appeared specific to this protein since neither annexin I nor annexin II (tetramer) could evoke any 45Ca2+ release. Given the predominant localization of A-VI to the apical plasmalemma, these results suggest that this protein could participate in the secretory event by mediating the localized release of Ca2+ at sites of contact between the chromaffin granule and plasma membrane.

Using the radionuclide salivagram to detect pulmonary aspiration and esophageal dysmotility

That the radionuclide "milk" scan is insensitive for aspiration has been demonstrated. Here the authors review their experience with the radionuclide salivagram in its ability to detect aspiration in children. Tc-99m sulfur colloid, 0.5 to 1.0 mCi in less than 1 mL, is instilled into the mouth and sequential supine posterior images of the thorax are obtained for an hour with delayed images until the oropharynx is cleared of radiotracer. Fourteen studies have been performed in 13 patients aged 1 month to 6.5 years. There are scintigraphic findings consistent with aspiration in 4 of 14 studies (28%); dysmotility (prolonged retention of activity in the esophagus) in 7 of 14 studies (50%); and normal studies in 3 of 13 patients (22%). Eight of 13 patients had milk scans; all were negative for aspiration. One patient studied twice had aspiration on the first examination, and dysmotility on the second study. It is concluded that the salivagram can detect aspiration of oral secretions, is superior to the milk scan in detecting aspiration, and can demonstrate esophageal dysmotility.

The effects of television viewing on preoperative anxiety

Previous studies have looked at the relationship between preoperative anxiety and postoperative course. However, few studies have looked at methods to decrease preoperative anxiety. To investigate preoperative anxiety and possible anxiety reduction strategies, the investigators devised a clinical study to examine the effects of television viewing on preoperative anxiety. The study compared patients who were not able to watch television in the preoperative setting with those who were. The investigators hypothesized that television viewing in the preoperative setting would decrease preoperative anxiety. A purposive sampling method was chosen so that the study population could be selected using certain criteria. The sample consisted of adult patients 18 to 77 years old who were admitted to the preoperative area at least 2 hours before surgery. A total of 76 subjects participated in the study. However, due to incomplete data on seven of the questionnaires, 7 of the subjects were rejected. Of the remaining 69 subjects, 39 had no television access and the remaining 30 did. Statistical comparisons of the two groups suggest that there was a significant difference in the anxiety levels of the two groups. As hoped, the hypothesis was proven correct: Those subjects who watched television in the preoperative area had significantly lower levels of anxiety than those who did not.

Purification and characterization of annexin proteins from bovine lung

Calcium-dependent association with a detergent-extracted particulate fraction was used as the first step in the purification of a group of phospholipid binding proteins. Elution of the detergent-insoluble fraction with excess ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) resulted in the release of several soluble proteins, termed calcium-activated proteins or CAPs. In the present paper, we describe the simultaneous purification of these CAPs and characterize their interaction with phospholipid, actin, and calmodulin. Partial sequence analysis has identified the majority of the CAPs as members of the annexin family of calcium and phospholipid binding proteins. Two additional CAPs may be novel proteins, one of which appears to be an annexin protein. All CAPs demonstrated Ca2(+)-dependent binding to phosphatidylserine vesicles but did not bind to phosphatidylcholine vesicles. The majority of CAPs exhibited Ca2(+)-dependent binding to F-actin; however, only CAP-III affected the rate of conversion of G-actin to F-actin. The interaction of CAP-III and lipocortin-85 with F-actin resulted in a Ca2(+)-dependent increase in both light scattering and sedimentation of F-actin under comparatively low centrifugal force. In contrast, only lipocortin-85 caused the formation of F-actin bundles. Although all of the CAPs bound to a calmodulin affinity column in a Ca2(+)-dependent manner, attempts to demonstrate binding of CAPs to native calmodulin were unsuccessful. These studies therefore document the similar behavior of the CAPs toward phospholipid and calmodulin but clearly show that F-actin binding or bundling is not a general property of these proteins. The reported purification procedure should allow further comparative studies of these proteins.

Using nurses for preventive activities with computer assisted follow up: a randomised controlled trial

OBJECTIVE

To assess whether an organised programme of prevention including the use of a health promotion nurse noticeably improved recording and follow up of cardiovascular risk factors and cervical smears in a general practice that had access to computerised cell and recall.

DESIGN

Randomised controlled trial.

SETTING

General practice in inner London.

PATIENTS

All 3206 men and women aged 30-64 registered with the practice.

INTERVENTION

The intervention group had their risk factors ascertained and followed up by the health promotion nurse and the general practitioner, whereas those in the control group were managed by the general practitioner alone.

END POINT

Recording and follow up of blood pressure and cervical smears after three years. Recording of smoking, family history of ischaemic heart disease, and serum cholesterol concentrations were also examined.

MEASUREMENTS AND MAIN RESULTS

When the trial was stopped after two years the measurements of blood pressure in the preceding five years were 93% (1511/1620) v 73% (1160/1586) (95% confidence interval for difference 17.5 to 22.7%) for intervention and control groups respectively. For patients with hypertension the figures were 97% (104/107) v 69% (80/116) (18.2 to 38.2%). For women the proportion who had had a cervical smear in the preceding three years were 76% (606/799) v 49% (392/806) (22.5 to 31.9%). Recording of smoking, family history of ischaemic heart disease, and serum cholesterol concentrations was also higher in the intervention group compared with the control group.

CONCLUSION

An organised programme, which includes a nurse with specific responsibility for adult prevention, is likely to make an important contribution to recording of risk factors and follow up of those patients with known risks.

Health care needs of Indochinese refugee teenagers

Although 50% of Indochinese refugees are under 18 years of age, previous studies have emphasized the prevalence of parasites, anemia, tuberculosis, and hepatitis, with few addressing age-related health care needs. In this study the specific health care needs of 80 Indochinese refugee teenagers, evaluated during a 4-year period, were determined. The Centers for Disease Control's suggested screening measures were used, and it was found that 52% had positive purified protein derivative skin tests, 38% lacked immunizations, 35% had stool specimens positive for parasites (prevalence and number of parasites greatest among Cambodians), 14% had blood tests positive for hepatitis B surface antigen, and 10% were anemic. Additional evaluations showed that 19% had hemoglobinopathies, 14% were in or below the fifth percentile for height and weight, 12% had goiters, 12% had skin disorders, 8% had positive hepatitis B surface antigen, 5% had visual defects, 5% had hearing loss, 5% had psychosomatic illness, and 4% had idiopathic scoliosis. Although suggested Centers for Disease Control screening measures may be adequate for younger Indochinese children, these data suggest that additional studies are necessary for teenagers. For the sexually active adolescent, identification of and counseling for hepatitis antigenemia and hemoglobinopathies are crucial. In addition, early identification of emotional and physical problems during screening may enhance assimilation into a new society and facilitate completion of the psychosocial tasks of adolescence.

Nifedipine inhibits hypoxic pulmonary vasoconstriction during rest and exercise in patients with cystic fibrosis and cor pulmonale

Nifedipine has recently been reported to reduce pulmonary artery pressure and pulmonary vascular resistance during rest and exercise in adult patients with hypoxic pulmonary hypertension from chronic obstructive pulmonary disease. To determine whether nifedipine reduces pulmonary vascular resistance in patients with cor pulmonale from cystic fibrosis (CF), we studied 2 patients with severe CF lung disease during rest and exercise while breathing room air or receiving low-flow oxygen therapy. Nifedipine markedly lowered pulmonary vascular resistance and improved cardiac index and pulmonary pressure-flow relationships during all treatment conditions. Nifedipine did not substantially change arterial PO2, except for a slight decrease during exercise while receiving low-flow oxygen. Nifedipine, however, markedly increased oxygen delivery during rest and exercise. Both patients noted improved exercise tolerance with chronic nifedipine therapy. Nifedipine may be a useful adjuvant to supplemental oxygen in the treatment of patients with CF and cor pulmonale.

Purification and characterization of acidic fibroblast growth factor from bovine brain

Acidic brain fibroblast growth factor has been purified a minimum of 35,000-fold to apparent homogeneity by a combination of differential salt precipitation, ion exchange chromatography, gel filtration, isoelectric focusing, and hydrophobic chromatography on a C4 reversed-phase HPLC column. Two microheterogeneous forms of the molecule are obtained with apparent molecular masses of 16,600 and 16,800 daltons. The mitogen is highly active with half-maximal stimulation of BALB/c 3T3 fibroblasts at about 40 pg/ml in an assay using incorporation of [methyl-3H]thymidine into DNA.