Tetrahydrobiopterin increases myocardial blood flow in healthy volunteers: a double-blind, placebo-controlled study

OBJECTIVES

Tetrahydrobiopterin (BH4) is a regulatory cofactor for the activity of nitric oxide synthases. Vasodilating properties of BH4 have been reported in vitro and in vivo. The influence of BH4 on myocardial blood flow (MBF), however, is largely unknown. We therefore performed a double-blind, placebo-controlled study to investigate the effect of intravenous BH4 on MBF in healthy volunteers.

METHODS AND RESULTS

Resting MBF was assessed in 15 subjects receiving either intravenous BH4 (10 mg/kg) or placebo using positron emission tomography (PET) and [13N]ammonia. From a mean baseline MBF of 0.91 +/- 0.09 ml/min/g, MBF increased to 1.18 +/- 0.10 ml/min/g after BH4 (n = 10; p = 0.0042). In contrast, in the group receiving placebo mean MBF remained unchanged (non-significant decrease from 0.97 +/- 0.19 to 0.84 +/- 0.11 ml/min/g; n = 5; p = 0.36). Systemic haemodynamics and ECGs remained unaffected in both groups. BH4 was very well tolerated.

CONCLUSION

Systemically administered BH4 is safe and effectively increases resting MBF in healthy volunteers.

Tetrahydrobiopterin increases myocardial blood flow in healthy volunteers: a double-blind, placebo-controlled study

OBJECTIVES

Tetrahydrobiopterin (BH4) is a regulatory cofactor for the activity of nitric oxide synthases. Vasodilating properties of BH4 have been reported in vitro and in vivo. The influence of BH4 on myocardial blood flow (MBF), however, is largely unknown. We therefore performed a double-blind, placebo-controlled study to investigate the effect of intravenous BH4 on MBF in healthy volunteers.

METHODS AND RESULTS

Resting MBF was assessed in 15 subjects receiving either intravenous BH4 (10 mg/kg) or placebo using positron emission tomography (PET) and [13N]ammonia. From a mean baseline MBF of 0.91 +/- 0.09 ml/min/g, MBF increased to 1.18 +/- 0.10 ml/min/g after BH4 (n = 10; p = 0.0042). In contrast, in the group receiving placebo mean MBF remained unchanged (non-significant decrease from 0.97 +/- 0.19 to 0.84 +/- 0.11 ml/min/g; n = 5; p = 0.36). Systemic haemodynamics and ECGs remained unaffected in both groups. BH4 was very well tolerated.

CONCLUSION

Systemically administered BH4 is safe and effectively increases resting MBF in healthy volunteers.

Influence of D- and L-glucose on erythrocytes and blood viscosity

BACKGROUND

Elevated blood glucose levels are associated with substantial morbidity and mortality. The pathomechanism behind it is not well understood. The aim of the present study was to investigate the effect of glucose on blood rheology.

MATERIALS AND METHODS

Blood from healthy volunteers was incubated with various concentrations of D- and L-glucose for 1 h at 37 degrees C. Whole blood viscosity at haematocrit 45% was measured at high and low shear rate (94.5 and 0.1 s(-1)). Erythrocyte shape and volume were assessed. Haemoglobin solutions were incubated with D-glucose for up to 96 h and the viscosity was measured.

RESULTS

D-glucose dissolved in H2O and diluted with isotonic NaCl, added to whole blood (additional D-glucose concentrations 0-80 mM), led to a red cell swelling and an increase in blood viscosity at low shear rate (0.1 s(-1)). This process was reversible upon removal of D-glucose. L-glucose, which is not transported into the red cell by the D-glucose-specific transport protein GLUT-1, had no effect. When D-glucose was dissolved and diluted in autologous plasma, haematocrit and viscosity remained unaffected, but L-glucose decreased both values. Incubation of a haemoglobin solution with D-glucose at 37 degrees C led to a time-dependent increase in glycosylated haemoglobin (HbA1C) up to 8%, but left the viscosity unchanged.

CONCLUSION

Blood glucose tested in a wide range of concentrations did not affect blood viscosity and morphological or biophysical properties of erythrocytes.

Geographic pattern of genetic variation in Pinus resinosa: area of greatest diversity is not the origin of postglacial populations

Genetic diversity is low in natural populations of red pine, Pinus resinosa, a species that has a vast range across north-eastern North America. In this study, we examined 10 chloroplast microsatellite or simple sequence repeats (cpSSR) loci in 136 individuals from 10 widespread populations. Substantial variation for the cpSSR loci was observed in the study populations. The contrast with red pine's lack of variation for other types of loci is likely to be due to the higher mutation rates typical of SSR loci. The amount of variation is lower than that generally found for cpSSR loci in other pine species. In addition, the variation exhibits a striking geographical pattern. Most of the genetic diversity is among populations, with little within populations, indicating substantial isolation of and genetic drift within many populations in the southern half of the species distribution. The greatest diversity now occurs in the north-eastern part of New England, which is especially intriguing because this entire area was glaciated. Thus the centre of diversity cannot be the origin of postglacial populations, rather it is likely caused by admixture, most probably because of influences from two separate refugia. Furthermore, the pattern indicates that the spread of red pine since the last glaciation is rather more complex than usually described, and it likely includes more than one refugia, complex migration routes, and postglacial-retreat isolation and genetic drift among shrinking populations in regions of the present southern range.

[Reactivation of herpes virus infections by vaccination: evidence or coincidence?]

Varicella zoster and herpes simplex viruses cause latent infections by persisting in human cells. Reactivation has been associated with increasing age, immunosuppression, cancer, stress, fever, exposure to ultraviolet light, and tissue damage. Based on three cases reported to the Swiss Drug Monitoring Centre SANZ, we postulated previously that vaccinations may trigger reactivation of herpes virus infections due to vaccine-induced immunomodulation. In the meantime, 10 new cases of reactivated herpes virus infections soon after vaccinations have been reported. They involved 5 women and 5 men with an age range between 16 and 60. In only one case had a trauma preceded, otherwise healthy subjects with no known relevant comorbidity were vaccinated. The clustering of reports after publication points to a previous underreporting of similar cases. This may be explained by the fact that both vaccinations and reactivations of herpes virus infections are frequent, and a causal link is not suspected. However, these new cases do not prove causality, and extensive epidemiological or experimental studies are needed to elucidate the possible link between vaccination and reactivation of herpes virus infections.

Increased expression of mature cathepsin B in aging rat liver

Senescence has been proposed as an important safeguard against neoplasia. One of the hallmarks of cellular senescence in vitro as well as human aging in vivo is a reduced intracellular protein catabolism. The pathways affected and the mechanisms responsible for the decrease in overall protein turnover in aging cells are not well understood. Our aim was to determine whether or not expression of one of the major hepatic lysosomal cysteine peptidases, cathepsin B, changes during aging of Sprague-Dawley rats. Cathepsin B activity was assessed in whole rat liver homogenates, and was found to be increased fourfold (P< or =0.001) in aged livers compared with younger counterparts. This was paralleled by an at least a twofold increase in mature cathepsin B protein. Nonetheless, Northern blot analysis of total liver RNA revealed no change in steady-state levels of cathepsin B mRNAs. These findings seem to contradict the present dogma according to which aging tissues have a reduced intracellular capacity to catabolise proteins. We propose that our earlier observation of the accumulation of T-kininogen, a potent but reversible cysteine peptidase inhibitor, in aging rat liver may provide a plausible explanation for this discrepancy.

Modulation of the ERK pathway of signal transduction by cysteine proteinase inhibitors

Cell proliferation requires the coordinate synthesis and degradation of many proteins. In addition to the well-characterized involvement of the proteasome in the degradation of several cell cycle-regulated proteins, it has been established that cysteine proteinases are also involved in the control of cell proliferation, but their role is currently not understood. By using both synthetic cysteine proteinase inhibitors and overexpression of T-kininogen (T-KG), a physiologically relevant cysteine proteinase inhibitor, we show that inhibition of cysteine proteinases results in a severe inhibition of the ERK pathway of signal transduction. Mechanistically, this effect appears to be the result of stabilization of the ERK phosphatase MKP-1, which leads to an enhanced dephosphorylation (and hence inactivation) of ERK molecules. These results are specific to cysteine proteinase inhibitors and are not observed when either serine proteinases or the proteasome are inhibited. We hypothesize that inhibition of cysteine proteinases in vivo leads to a dysregulation of the ERK pathway, which results in an inability of the cell to transmit to the nucleus the signals generated by the presence of growth factors, thus resulting in loss of cell proliferation.

Enhanced transcription of the s-adenosylhomocysteine hydrolase gene precedes Epstein-Barr virus lytic gene activation in ganglioside-stimulated lymphoma cells

Stimulation of Epstein-Barr virus (EBV) genome-positive Burkitt lymphoma cells with the ganglioside IV3NeuAc-nLcOse4Cer leads to the induction of cell differentiation processes and activates the EBV lytic viral cycle. In cells of the Burkitt lymphoma line Raji differential expression of host cell genes was analysed in the early phase (150 min) post stimulation with the ganglioside to display the cell activities that precede the activation of the EBV lytic cycle using the differential display reverse transcription-polymerase chain reaction technique. Multiple fragment cDNAs derived from control cells and ganglioside-stimulated cells were amplified using random primers and displayed via polyacrylamide gel electrophoresis. The expression pattern of 8,400 bands was analysed. Eleven differentially expressed fragment cDNAs were reamplified and identified by nucleotide sequencing. Six of these could be identified as coding for proteins that may take part in virus reactivation and differentiation. The most striking finding was the induction of s-adenosylhomocysteine hydrolase (AHCY) expression. The cellular enzyme AHCY plays an important role in transmethylation reactions controlling the replication of several viruses. Thus. an involvement in EBV replication can be suggested.

Environmental and genetic risk factors and gene-environment interactions in the pathogenesis of chronic obstructive lung disease

Current understanding of the pathogenesis of chronic obstructive pulmonary disease (COPD), a source of substantial morbidity and mortality in the United States, suggests that chronic inflammation leads to the airways obstruction and parenchymal destruction that characterize this condition. Environmental factors, especially tobacco smoke exposure, are known to accelerate longitudinal decline of lung function, and there is substantial evidence that upregulation of inflammatory pathways plays a vital role in this process. Genetic regulation of both inflammatory responses and anti-inflammatory protective mechanisms likely underlies the heritability of COPD observed in family studies. In alpha-1 protease inhibitor deficiency, the only genetic disorder known to cause COPD, lack of inhibition of elastase activity, results in the parenchymal destruction of emphysema. Other genetic polymorphisms have been hypothesized to alter the risk of COPD but have not been established as causes of this condition. It is likely that multiple genetic factors interacting with each other and with a number of environmental agents will be found to result in the development of COPD.

Establishment and characterization of an arsenic-sensitive monoblastic leukaemia cell line (SigM5)

Few human monoblastic cell lines have been characterized to date. We have established the SigM5 cell line from a patient with acute monoblastic leukaemia (FAB M5a). Original leukaemic cells had a karyotype of 47,XY,+8, whereas the cell line showed a stemline clone of 81,XX,Y,Y,1,4,6,7,+8,+8,9,10,10,11,13,16,19[cp], with a minor sideline also present. Cytochemical staining was strongly positive with alpha-naphthylbutyrate acetate esterase, particulate positive with Sudan black and weakly positive for myeloperoxidase. Cells were positive for CD13, CD15, CD18, CD23, CD33, CD38, CD45, CD68 and myeloperoxidase. CD14 expression was 3-15%. SigM5 constitutively secreted interleukin (IL)-2, IL-8, IL-10, tumour necrosis factor (TNF)-alpha, ferritin, lysozyme, N-elastase and neopterin upon stimulation with interferon (IFN)-gamma. Cells expressed the proinflammatory mediator macrophage migration inhibitory factor (MIF). All NADPH oxidase subunits were constitutively present, but nitroblue tetrazolium reduction was only detectable upon activation with IFN-gamma. SigM5 monoblasts were sensitive to arsenic trioxide (As2O3) previously not described to induce apoptosis in monoblastic cells. Differing considerably in morphology, immunophenotype and sensitivity to arsenics from the widely used cell lines U937, HL-60 and THP-1, SigM5 is a new monoblastic cell line useful for studying leukaemogenesis, monocyte differentiation and tumour cell susceptibility to arsenic compounds.

Hypocaloric parenteral nutrition support in elderly obese patients

Hypocaloric nutritional support has been successfully used to achieve positive nitrogen balance in obese patients. However, advanced age is associated with changes in substrate metabolism. To evaluate the efficacy of this practice in elderly patients, we retrospectively reviewed 30 obese patients requiring parenteral nutrition support. Total caloric requirements (TCR) were calculated on the basis of the Harris-Benedict equation. Patients were given a minimum of 1.5 g/kg/day protein, 75 per cent of TCR when current body weight was >120 and < or =150 per cent of ideal body weight (IBW), and 60 per cent of TCR if current body weight was >150 per cent of IBW. The patients were divided into two groups: Group I (N = 18) patients were age <60 and Group II (N = 12) patients were > or =60 years of age. Only one of the Group I patients (143.2 +/- 25.7% IBW, received 18.2 +/- 3.7 kcal/kg/day and 1.6 +/- 0.4 g/kg/day protein), but five of the Group II patients (141.3 +/- 14.4% IBW, received 18.3 +/- 2.6 kcal/kg/day and 1.7 +/- 0.3 g/kg/day protein), had negative nitrogen balance (P = 0.025). Apparently, elderly obese patients have limited capacity to mobilize their fat stores as energy sources and may continue to undergo protein catabolism with hypocaloric high-protein nutrition support. Therefore, this form of nutritional support should be used with caution in elderly obese patients.

Influence of parathyroid hormone, calcitonin, 1,25(OH)2 cholecalciferol, calcium, and the calcium ionophore A23187 on erythrocyte morphology and blood viscosity

Parathyroid hormone and calcitonin, both endocrine modulators of calcium homeostasis, may influence blood rheology. Parathyroid hormone is known to reduce erythrocyte survival, leading to anemia. Calcitonin has been found to have some vascular effects. We have analyzed the Influence of parathyroid hormone (10(-7) to 10(-10) mol/L), calcitonin (10(-6) to 10(-12) mol/L), 1,25(OH)2 cholecalciferol (10(-7) to 10(-10) mol/L), additional calcium in plasma (+1 and 2 mmol/L), and the calcium lonophore A23187 (50 micromol/L) on erythrocyte morphology and blood viscosity at high shear rate (94 s(-1)) and low shear rate (0.1 s(-1)) in vitro. The loading of erythrocytes with calcium by the ionophore A23187 produced a marked echinocytic shape transformation, an increased blood viscosity at high shear rate caused by decreased deformability of these cells, and a decreased viscosity at low shear rate caused by decreased aggregation of echinocytes. In contrast, increasing plasma calcium concentrations, parathyroid hormone, calcitonin, and 1,25(OH)2 vitamin D3 had no effect on erythrocyte morphology and blood viscosity. We conclude that an increase in intraerythrocytic calcium leads to severe echinocytosis and altered blood viscosity. The endocrine modulators of calcium homeostasis--namely, parathyroid hormone, calcitonin, and 1,25(OH)2 vitamin D3--apparently do not influence intraerythrocytic calcium to a significant degree and have, therefore, no influence on cell morphology and blood viscosity.

An Experience of Peer Mentoring with Student Nurses: Enhancement of Personal and Professional Growth

This article discusses the importance of peer mentoring in nursing education. The current literature is reviewed and areas for further research are identified. Most specifically, the article explores the results of a recent research study conducted at Southern Cross University in Australia. The research investigated the relationship between personal and professional growth and peer mentoring with a group of women nurses. Seven nurses participated in this qualitative research project. Six of the participants were student nurses enrolled in an undergraduate nursing degree and the seventh participant was the degree program coordinator. The research was conducted over a 12-week period and was located in critical paradigm. The research methods used were reflective journaling and interviewing. The results indicated that the process of peer mentoring in nursing education demonstrated a strong relationship to personal and professional growth for all of the participants. Characteristics of the peer mentoring process such as shared learning, shared caring, reciprocity, commitment to each other's personal and professional growth, and friendship, are discussed.

Pharmacological concentrations of arginine influence human whole blood viscosity independent of nitric oxide synthase activity in vitro

l-Arginine, the natural precursor of NO, is infused in patients to restore endothelial function. Concentrations up to 7.5 mM l-arginine have been measured after parenteral administration. We investigated whether such high concentrations of amino acids influence blood viscosity in vitro. Incubation of whole blood from healthy volunteers with l-arginine, d-arginine, which has no effect on stereospecific NO synthases (NOS), the NOS substrate L-AME, the NOS inhibitor L-NNA, the amino acids l-lysine and l-glutamic acid, and finally NaCl dose-dependently decreased (up to 30% at 10(-2) M) low shear viscosity, which is primarily determined by erythrocyte aggregation. In contrast, the lipophilic NOS inhibitor L-NAME had no effect on low shear viscosity. All molecules failed to influence high shear viscosity, which is primarily determined by red cell deformability, and the erythrocyte shape remained unaltered. We conclude that high concentrations amino acids may decrease blood viscosity at low shear rate independent of NOS activity. This effect may contribute to the improved blood flow after intravascular administration of l-arginine.

Impaired signal transduction in mitogen activated rat splenic lymphocytes during aging

Mitogen activated protein kinases (MAPK) are activated by a wide variety of signals leading to cell proliferation and differentiation in different cell types. With aging, there is a marked decrease in proliferation of T-lymphocytes in response to a variety of mitogens. Several age-related changes in the activation of MAPK pathways in T-lymphocytes activated via the T-cell receptor (TCR) have been described in different species. This way, some TCR proximal defects in tyrosine kinase activity have been delineated. In this study, we have used rat splenic lymphocytes to measure the effect of aging on the activation of two MAP kinase families: ERK and JNK. In order to bypass the receptor-proximal age-dependent defects previously described, we used phorbol ester (PMA) and Ca2+ ionophore (A23187) as co-mitogens. Our results demonstrate that splenic lymphocytes from old rats have a disturbance in the activation of the ERK and JNK MAPK signal transduction pathways, that are located downstream of the receptor-proximal events. At least part of the age-related defect leading to decreased ERK activity appears to be located upstream of ERK itself, since activation of MEK is also impaired. On the other hand, the observed defects in MAPK activation do result in decreased activation of downstream events, such as c-Jun phosphorylation. Thus, we conclude that aging of splenic lymphocytes results in a functional decline in signal transduction, and at least some of these defects are located downstream of the receptor-proximal events previously described by others. The impaired activity of these two MAP kinase pathways is likely to play a role in the diminished lymphoproliferation observed in old individuals.

The nitric oxide synthase cofactor tetrahydrobiopterin reduces allograft ischemia-reperfusion injury after lung transplantation

OBJECTIVE

Exogenous nitric oxide reduces ischemia-reperfusion injury after solid organ transplantation. Tetrahydrobiopterin, an essential cofactor for nitric oxide synthases, may restore impaired endothelium-dependent nitric oxide synthesis. We evaluated whether tetrahydrobiopterin administration to the recipient attenuates lung reperfusion injury after transplantation in swine.

METHODS

Unilateral left lung transplantation was performed in 15 weight-matched pigs (24-31 kg). Donor lungs were flushed with 1.5 L cold (1 degrees C) low-potassium-dextran solution and preserved for 20 hours. Group I animals served as controls. Group II and III animals were treated with a bolus of tetrahydrobiopterin (20 mg/kg). In addition, in group III a continuous infusion of tetrahydrobiopterin (10 mg/kg per hour over 5 hours) was given. One hour after reperfusion, the recipient right lung was occluded. Cyclic guanosine monophosphate levels were measured in the pulmonary venous and central venous blood. Extravascular lung water index, hemodynamic variables, lipid peroxidation, and neutrophil migration to the allograft were assessed.

RESULTS

In group III a significant reduction of extravascular lung water was noted in comparison with the controls (P =.0047). Lipid peroxidation in lung allograft tissue was significantly reduced in group II (P =.0021) and group III ( P =. 0077) in comparison with group I. Pulmonary venous levels of cyclic guanosine monophosphate increased up to 23 +/- 1 pmol/mL at 5 hours in group II and up to 40 +/- 1 pmol/mL in group III (group I, 4.1 +/- 0.5 pmol/mL [I vs III]; P <.001), whereas central venous levels of cyclic guanosine monophosphate were unchanged in all groups.

CONCLUSION

Tetrahydrobiopterin administration during lung allograft reperfusion may reduce posttransplantation lung edema and oxygen-derived free radical injury in the graft. This effect is mediated by local enhancement of the nitric oxide/cyclic guanosine monophosphate pathway.

A membrane-located glycosphingolipid of monocyte/granulocyte lineage cells induces growth arrest and triggers the lytic viral cycle in Epstein-Barr virus genome-positive Burkitt lymphoma lines

Gangliosides are known to influence cell growth and differentiation. The neolacto series ganglioside IV3NeuAc-nLc4 (2-->3-sialosylparagloboside) is present in members of the monocyte/granulocyte lineage, but is not found in cells that belong to the lymphocyte lineage. In this study we demonstrated that IV3NeuAc-nLc4 inhibits the proliferation of Epstein-Barr virus (EBV) genome-positive Burkitt lymphoma cells of the lines Raji and P3HR-1K. IV3NeuAc-nLc4-induced growth inhibition is associated with an increase in G0/G1 phase cells and a reduced expression of CD21 and HLA-DR antigens on Raji cells. These data suggest that IV3NeuAc-nLc4 may affect differentiation of lymphoma cells. Additionally, the increased expression of viral mRNA species which are characteristic for the lytic viral cycle in the non-producer line Raji and the enhanced release of virions from the producer line P3HR-1K demonstrate that IV3NeuAc-nLc4 activates the replication of EBV. Growth inhibition and termination of the viral latency suggest that IV3NeuAc-nLc4 present in monocyte/granulocyte lineage cells may be an effector of the natural defense against EBV persistency and transformation.

Mosquito cathepsin B-like protease involved in embryonic degradation of vitellin is produced as a latent extraovarian precursor

Here we report identification of a novel member of the thiol protease superfamily in the yellow fever mosquito, Aedes aegypti. It is synthesized and secreted as a latent proenzyme in a sex-, stage-, and tissue-specific manner by the fat body, an insect metabolic tissue, of female mosquitoes during vitellogenesis in response to blood feeding. The secreted, hemolymph form of the enzyme is a large molecule, likely a hexamer, consisting of 44-kDa subunits. The deduced amino acid sequence of this 44-kDa precursor shares high similarity with cathepsin B but not with other mammalian cathepsins. We have named this mosquito enzyme vitellogenic cathepsin B (VCB). VCB decreases to 42 kDa after internalization by oocytes. In mature yolk bodies, VCB is located in the matrix surrounding the crystalline yolk protein, vitellin. At the onset of embryogenesis, VCB is further processed to 33 kDa. The embryo extract containing the 33-kDa VCB is active toward benzoyloxycarbonyl-Arg-Arg-para-nitroanilide, a cathepsin B-specific substrate, and degrades vitellogenin, the vitellin precursor. Both of these enzymatic activities are prevented by trans-epoxysuccinyl-L-leucylamido-(4-guanidino)butane (E-64), a thiol protease inhibitor. Furthermore, addition of the anti-VCB antibody to the embryonic extract prevented cleavage of vitellogenin, strongly indicating that the activated VCB is involved in embryonic degradation of vitellin.

Primary pleomorphic adenoma of the external auditory canal diagnosed by fine needle aspiration cytology. A case report

BACKGROUND

Pleomorphic adenoma (PA) arising in the external auditory canal (EAC) is a very rare neoplasm, thought to be derived from ceruminous glands.

CASE

A 43-year-old male presented with a slowly growing mass in the right EAC. Clinical and radiologic examinations showed a well-circumscribed tumor limited to the EAC, without a connection to the parotid gland. Fine needle aspiration cytology (FNAC) revealed the typical cytologic findings of PA. The diagnosis was confirmed by histologic examination.

CONCLUSION

This case illustrates that together with clinical and radiologic findings, primary PA of the EAC can confidently be diagnosed by FNAC.

Discovery of self: exploring, interconnecting and integrating self (concept) and nursing

Self concept of individual nurses is still largely unexplored in nursing. While the role of self-knowledge and self-actualisation are recognised as integral to nursing practice, little has been done to examine their relationships to self concept and nursing practice. The aim of this research study was to explore the role and significance that self concept plays in women nurses' experience of their beginning practice. The exploration examined factors which contribute to and impact on self concept within a nursing practice environment. Self concept relates to how an individual experiences oneself and is integrally linked to one's interactions and relationships with others. This two phase research was situated in critical and feminist theory using reflective journalling (phase one) and story telling/narrative (phase two) as the research methods. This paper discusses the three major themes which arose in phase one of the research. Those were: exploring experiences; interconnecting personal and professional worlds; and, integrating self 'into' nursing. The paper also explores inter-subjectivity in terms of the contribution this concept makes to our understanding of research findings.

Morphometric analysis of pancreatic carcinoma by computer-assisted image analysis

This report describes the results of applying the interactive image analysis system for the measurement of some cytological parameters corresponding to features of adenocarcinoma of the pancreas. The present experiments were carried out by means of the digital cell image analysis of haematoxilyn and eosin stained archival standard glass slides of cancer bearing and healthy patients. Four different parameters describing the morphology of nuclei and nucleoli were selected to quantitate the differences between control and malignant tissues: area, perimeter, elongation, and extension. The parameters that showed the greatest differences between cancerous and normal pancreas were: area and elongation in the case of nuclei as well as area and perimeter for nucleoli. However, the results of this study suggest that none of the four analysed parameters can be selected alone to discriminate neoplastic from normal cells, but could be used all together in diagnosis of pancreatic cancer.

Urodynamic verification of noninvasive back-pressure recordings from the urinary bladder

Obstructive voiding is best evaluated with urodynamics, especially simultaneous measurement of bladder-pressure and urine flow rates. As an alternative to catheterization for urodynamics, noninvasive back-pressure methods using an external condom system have been introduced. This device uses one side tube in the condom for pressure recording and an outlet tube that is clamped for short periods of time during voiding. However, there have been problems with accurate back-pressure recording, including leaking, clamping techniques, hydrostatic pressures associated with pressure recording below the level of the symphysis pubis, and assessment of back pressures in relation to bladder and detrusor pressures. To address these issues, we have modified the condom for passing a catheter into the urethra for simultaneous direct bladder and back-pressure recording. The clamping device on the outlet tube also has been modified to produce back flushing of urine in addition to clamping. Hydrostatic issues have been addressed by making pressure recordings at the level of the symphysis pubis. Seven patients with obstructive symptoms were evaluated using these new devices. Back pressures were not statistically different than detrusor pressures recorded with a urethral catheter. Thus, the modifications have improved back-pressure recording techniques. The use of noninvasive back-pressure recording may be an important adjunct in the evaluation of obstructive uropathy.

T-kininogen is a biomarker of senescence in rats

We have previously reported on the identification of T-kininogen (T-KG) as a gene whose expression is increased during senescence in male Sprague-Dawley (S-D) rats. Serum T-KG levels increase 2.5-4 months before the time of death for any given animal, irrespective of the actual age of the animal at the time of this event. Furthermore, dietary restriction (DR) delays, but does not prevent, the increase in serum T-KG levels. In the present study, we have assessed whether or not the age-related increase in T-KG is a common feature of senescence in other strains of rat. We have analyzed hepatic T-KG mRNA levels in male Fischer 344 rats (F344), as well as in male and female (Fischer 344 x Brown Norway)F1 rats (F1). In both of these strains, we observed a dramatic increase in hepatic T-KG mRNA levels when male rats approach senescence. The mRNA levels behave similarly in F1 and S-D rats, in that the increase occurs late in life, and it is either repressed or delayed by DR. In contrast, the increase in T-KG mRNA levels in F344 rats occurs earlier in life, and is not significantly affected by DR. Young female F1 rats fed ad libitum (AL) show a statistically significant (P = 0.0009) 2.6-fold higher level of T-KG mRNA, as compared to their male counterparts. Thus, while we still observe an age-related increase in this parameter in both AL and DR female F1 rats, the difference is statistically significant (P = 0.0001) only in DR animals. We conclude that the increase in T-KG gene expression is a common feature of senescence and that, at least in males of these commonly used rat strains, T-KG can be used as a reliable biomarker of aging. Since the increase in T-KG gene expression does not appear to correlate with inflammatory processes, and since different strains of animals succumb to different pathologies, these results further suggest that the increase in T-KG expression might be related to the process of aging per se, rather than to any given age-related pathology.

Interferon- and streptolysin O-induced activation of protein kinases and inhibition of cytochrome P450-dependent monooxygenases in rats

Immunostimulants known to initiate cytokine production were found to decrease the activity of hepatic microsomal drug oxidative enzymes but to activate protein kinase C (PKC). The present study investigated the effects of immunostimulating doses of rat interferon-gamma (IFN, 670,000 units i.p.) and streptolysin O (SLO, 100 HU/kg i.v. for 5 days) on hepatic soluble, membrane-bound and nuclear PKC, 7-ethylresorufin-O-deethylase (EROD) and 7-pentylresorufin-O-deethylase (PROD) in male Wistar rats. The SLO- and IFN-mediated decrease of EROD and PROD activity was associated with a characteristic activation of the hepatic and spleenic PKC. In SLO- and IFN-treated animals activities of the cytosolic, membrane-bound and nuclear PKC were significantly higher than in respective controls. Our results suggest that a decrease in hepatic cytochrome P450 content as well as the decrease in the EROD and PROD activities are inversely related to the function of PKC.

Changes in hepatic DNA binding proteins as a function of age in rats

The process of aging is accompanied by many changes in gene expression, occurring in virtually all organs of the affected individual. Here we report on the relative changes in DNA binding activity of a panel of 15 different transcription factors in the liver of adult (15-month-old) and old (25-month-old) Sprague-Dawley rats. When expressed as a function of nuclear protein concentration, a great majority of the transcription factors analyzed do not show significant differences in DNA binding activities as a function of age, except activator protein 1 (AP-1) and nuclear factor-kappa B, both of which show increased activities in the older animals, and hepatocyte nuclear factor-3, which undergoes a switch from predominantly alpha and beta subspecies in the adults, to predominantly gamma subspecies in the old animals. Further examination of some of the members of the AP-1 complex using Western blot analysis indicates that the increase in binding activity of this particular complex might be due to an increase in the relative mass of Jun B, presumably resulting in a switch from predominantly c-Fos/Jun D in the young to c-Fos/Jun B complexes in the old animals. Nuclear extracts prepared from the liver of old animals yield less proteins per mass of DNA than similar extracts prepared from younger animals. Accordingly, if the data are analyzed as a function of genomic DNA, our results indicate that aging results in a consistent, but generally not statistically significant decrease in most transcription factor DNA binding activities, with AP-1, nuclear factor-kappa B, and transcription factor II D being the exception to this decline.

Exploring women's experiences: the critical relationship between nursing education, peer mentoring and female friendship

A research study was conducted in 1995 with seven women nurses from Southern Cross University, Australia. The aim of this research was to investigate the possible relationship between female friendship, mentoring and nursing education. The researchers comprised six second-year nursing degree students and the programme co-ordinator for the Bachelor of Nursing programme. This research was framed in an emancipatory paradigm of critical social science and feminist theory. Reflective journalising and interviewing were used as the research methods. The results indicated that there is an inextricable link between female friendship and peer mentoring. These two 'features' created a productive climate for shared learning, shared caring, reciprocity and commitment to one another's personal and professional growth.

The revolving door of hospital readmissions

The elderly comprise a growing percentage of the population. Home care providers find it increasingly important to monitor rates of hospital readmissions and prevent unnecessary readmissions from occurring. This effort requires a conscious, well-thought-out effort on the part of today's providers.

Induction of tetrahydrobiopterin synthesis in human umbilical vein smooth muscle cells by inflammatory stimuli

Tetrahydrobiopterin (BH4) is an obligatory cofactor and regulator of nitric oxide synthases (NOS). We evaluated the biosynthesis of BH4 in human umbilical vein smooth muscle cells (HUVSMC). Trace amounts of BH4 were found intra- and extracellularly in untreated cells. When HUVSMC were activated by individual inflammatory stimuli (IL-1beta, TNFalpha, IFNgamma or LPS), both intra- and extracellular levels of BH4 increased significantly, with TNFalpha being the most potent single stimulus. Combined inflammatory cytokines synergized in the induction of an up to 600-fold increase of BH4 synthesis. Addition of LPS to the cytokine mixture led to a further increase of BH4 synthesis. Neopterin, a product of the first intermediate in BH4 biosynthesis, was also raised, but to a much lesser extent. The increase of BH4 synthesis was paralleled by an enhanced expression of isoform-1 (the only isoform coding for the active enzyme) of GTP cyclohydrolase I in cytokine treated cells. Our results show for the first time that BH4 biosynthesis is strongly induced by combinations of inflammatory stimuli in HUVSMC. The importance of BH4-dependent NO synthesis in HUVSMC needs, however, additional detailed studies.

N,N-dimethyldioncophyllinium A iodide: synthesis, stereoanalysis, and antimalarial activity of the first N-quaternary naphthylisoquinolinium salt

The first synthesis of an N-quaternary salt of a naphthylisoquinoline alkaloid, N,N-dimethyldioncophyllinium A iodide, is described. For this potential natural product, a degradative procedure for the unambiguous stereoanalysis of the stereogenic centers has been elaborated. It shows enhanced anti-plasmodial activity in vitro towards Plasmodium falciparum erythrocytic forms, as compared to its less methylated precursors.

Inhalation of the nitric oxide synthase cofactor tetrahydrobiopterin in healthy volunteers

Pulmonary endothelial dysfunction is the hallmark of acute lung injury. Impaired pulmonary endothelial nitric oxide (NO) production in this event has been described. Tetrahydrobiopterin (BH4) is an essential cofactor for NO synthase and modulator of its activity. At high local concentrations, BH4 provokes local vasodilation in vivo in healthy individuals. At lower concentrations, BH4 selectively and locally restores disturbed NO-dependent vasodilation in patients with endothelial dysfunction. In this preliminary study, we therefore investigated the feasibility of BH4 inhalation in five healthy human volunteers. Inhalation of buffered, aqueous BH4-dihydrochloride solution was well tolerated; despite the buffer, BH4 stability was completely preserved. Resorption of inhaled BH4 was demonstrated by significantly increased BH4 levels in plasma and urine. Inhaled BH4 did not alter pulmonary function and had no effect on systemic hemodynamic values. Our data demonstrate that inhalation is a novel method for local BH4 administration, offering a basic therapeutic tool for investigation of restoration of impaired NO-dependent vasodilation due to pulmonary endothelial dysfunction.

Nitrite generation in interleukin-4-treated human macrophage cultures does not involve the nitric oxide synthase pathway

The search continues for high-output nitric oxide biosynthesis in human macrophages analogous to murine phagocytes. Recently, generation of nitrite in culture supernatants of human macrophages exposed to interferon-gamma and interleukin-4 (IFN-gamma/IL-4) was reported. The present study reproduces these findings and shows that L-arginine is not consumed and L-citrulline is not produced during this process. Furthermore, the biosynthesis of the obligatory cofactor tetrahydrobiopterin is not coinduced. These biochemical data provide support against a nitric oxide synthase contribution to nitrite accumulation. Nitrite was generated from nitrate salts even in cell-free media. Nitric oxide synthase activity but not nitrate reduction depended on molecular oxygen. Nitrite accumulation in experiments with IFN-gamma/IL-4 in human monocytes appears to be an in vitro artifact produced by nitrate-reducing activities contained in cytokine preparations.

Untroubled musical judgement of a performing organist during early epileptic seizure of the right temporal lobe

The case of a professional musician with a right temporal lobe epilepsy is presented. Whilst playing an organ concert (John Stanley's Voluntary VIII, Op. 5), he suffered a complex partial seizure. The recorded concert performance (with the seizure) was analysed and compared with other available exercise records and with the composition. The musical analysis of the seizure-induced variations reveals that at the beginning of the seizure, the left hand started to become unprecise in time and deviated from the score, whereas the right hand remained faultless at this time. With increasing duration of the seizure discharge, the dissociation of both hands from the score increased but the right hand compensated for the errors of the left hand in a musically meaningful way, i.e. with the aim to compensate for the seizure-induced errors of the left hand. The case illustrates untroubled musical judgement during epileptic activity in the right temporal lobe at the beginning of the seizure. Whereas the temporal formation of the performance was markedly impaired, the ability of improvisation-in the sense of a 'perfect musical solution' to errors of the left hand-remained intact.

Effects of activating and deactivating cytokines on the functionally linked tetrahydrobiopterin. No pathways in vascular smooth muscle cells

The functional relationship of nitric oxide (NO) production and synthesis of tetrahydrobiopterin (BH4), the requisite cofactor for NO synthase, was investigated in rat aortic smooth muscles cells (SMC). Inflammatory cytokines induced BH4 and NO synthesis in different ratios, IL-1 beta induced mainly NO synthesis with concomitant but limiting amounts of BH4 for maximal NO production. TNF alpha did not induce NO synthesis but induced BH4 synthesis. IFN gamma was ineffective on both the induction of NO and BH4 synthesis. TGF beta downregulated NO production but did not affect BH4 biosynthesis. IL-4 and IL-10 had no effect on both BH4 and NO synthesis. Activating cytokines strongly synergized in induction of NO production, whereas endogenous BH4 production became insufficient for maximal NO synthesis. Exogenous cofactor in the form of sepiapterin or authentic BH4, but not the natural isomer 7-BH4, enhanced NO production twofold. Inhibition of BH4 synthesis with dicumarol abolished NO production that could be restored in the presence of BH4.

Effects of interferon-gamma and streptolysin O on hepatic procainamide N-acetyltransferase and various microsomal cytochrome P450-dependent monooxygenases in rats

Immunostimulants known to initiate cytokine production were found to inhibit processes of microsomal drug oxidation but to activate arylamine N-acetylation. The present study investigated the effects of immunstimulating doses of rat interferon-gamma (IFN gamma, 670,000 units ip) and streptolysin O (SLO, 100 HU/kg iv for 5 days) on hepatic cytosolic N-acetyltransferase (NAT) and microsomal cytochrome P450 (CYP)-dependent monooxygenases in male Wistar rats. Both IFN gamma and SLO activated NAT to 120% (P < 0.05) and 135% (P < 0.05), respectively. As expected, monooxygenases were depressed by IFN gamma (P < 0.05) and SLO, the ethylresorufin O-deethylase being the most susceptible enzyme. The results suggested that not only the toxin of gram-positive streptococcal bacteria SLO, but also the cytokine IFN gamma can stimulate NAT activity in rat hepatic cytosol. While the enhancing SLO effect on NAT could not be neutralized by the inhibitor of transcription actinomycin D, NAT stimulation by IFN gamma was abolished by actinomycin D and by the inhibitor of translation, cycloheximide. Obviously, SLO activated NAT independent of protein synthesis and different from IFN gamma-mediated pathways. Posttranslational processes might be involved in NAT stimulation in the rats.

Crystal structure of soybean lipoxygenase L-1 at 1.4 A resolution

Lipoxygenases, which are widely distributed among plant and animal species, are Fe-containing dioxygenases that act on lipids containing (Z,Z)-pentadiene moieties in the synthesis of compounds with a variety of functions. Utilizing an improved strategy of data collection, low temperature, and synchrotron radiation of short wavelength, the structure of ferrous soybean lipoxygenase L-1, a single chain protein of 839 amino acid residues, has been determined by X-ray crystallography to a resolution of 1.4 A. The R-factor for the refined model is 19.7%. General features of the protein structure were found to be consistent with the results of prior crystallographic studies at lower (2.6 A) resolution. In contrast to the prior studies, the binding of a water molecule to the active site Fe was established. The octahedral coordination sphere of the Fe also includes the side chains of His499, His504, His690, and Asn694 as well as the terminal carboxylate of Ile839, which binds as a monodentate ligand. Asn694 is involved in a number of labile polar interactions with other protein groups, including an amide-aromatic hydrogen bond, and appears to be a weak ligand. Several possible access routes for dioxygen and fatty acids to the internal active site and substrate binding cavity are described. The protein structure restricts access to the Fe site such that the formation of an organo-Fe intermediate seems improbable. Structural restrictions pertinent to other proposed reaction intermediates, such as planar pentadienyl and nonplanar allyl radicals, are also discussed.

Influence of H2-receptor- and proton pump inhibitors on some functions of the oxydative and conjugative drug metabolism

There are numerous investigations describing the influence of histamine H2-receptor antagonists and proton pump inhibitors on cytochrome P450-mediated hepatic oxydative and conjugative drug metabolizing enzymes. The aim of this study was to investigate the influence of the H2-receptor blockers cimetidine, ranitidine, famotidine, nizatidine and of the proton pump inhibitors omeprazole and lansoprazole on the acetylation capacity and on different microsomal monooxygenases of the rat liver. The experiments were performed in two randomized studies with male Wistar rats after a 7-day pretreatment of the animals with antisecretory, equipotent doses of the investigational products. The activities of the arylamine N-acetyltransferase (NAT) and the microsomal enzymes were determined in vitro. Cimetidine and ranitidine decreased the activity of NAT significantly, no effect on this enzyme was observed after nizatidine. Small doses of famotidine tended to lower, high doses of famotidine tended to enhance the NAT activity. The proton pump inhibitor omeprazole significantly increased the NAT activity, lansoprazole evoked a small increase of the enzyme activity. Ethyl-resorufin O-deethylase (EROD) and penthlresorufin O-depentylase (PROD) were sensitive to cimetidine, ranitidine and famotidine. Only omeprazole and lansoprazole treatment inhibited the detromethorphan O-demethylase (DXDM) activity.

Effects of streptolysin O, polyriboinosinic-polyribocytidylic acid and combinations with cyclophosphamide on the hepatic arylamine N-acetyltransferase and cytochrome P450-dependent monooxygenases in rats

There is evidence that immunostimulation depresses the function of various cytochrome P450 (CYP)-dependent monooxygenases but activates the arylamine N-acetyltransferase (NAT). Therefore, the effects of the synthetic immunostimulator polyriboinosinic-polyribocytidylic acid (plC, 8 mg/kg i.p.), of sublytic doses of the streptococcal toxin streptolysin O (SLO, 50 HU/kg i.v. for 5 d) and of the immunosuppressor cyclophosphamide (CP, 100 mg/kg i.p.) on NAT and some monooxygenases were studied in rat liver. It was also evaluated whether CP might antagonize the effects of plC and SLO on drug metabolism. SLO, plC and CP reduced CYP content and the activities of some monooxygenases. NAT was significantly inhibited by CP (given 5 d before sacrifice) but not by plC, SLO or CP when given 2 d before sacrifice. CP lacked any effect on NAT if it was administered prior to SLO. However, it deteriorated synergistically the inhibition of the monooxygenases caused by SLO and plC.