Biomedical subjects

D Lang

Publications and source records attributed to D Lang.

At least 109 records · Page 6Linked to original sources

PubMed1996

Production and function of lipid second messengers in proliferating and differentiated neuroblastoma cells.

Multiple cellular responses are regulated through the generation of lipid second messengers upon activation of phospholipases. One such response concerns the activity of a class of kinase constituting the protein kinase C family. The production of specific molecular species of lipid second messengers may be therefore of prime importance in the activation of a member of the PKC isoforms. Prompted by this possibility we investigated the production of 1,2 diacyl-sn-glycerol (DAG) and phosphatidic acid (PtdOH) in LA-N-1 neuroblastoma cells under various physiological states. 12-0-Tetradecanoylphorbol 13-acetate (TPA) stimulation activated a phospholipase D (PLD) specific for phosphatidylcholine (PtdCho) in proliferating cells and a phospholipase C (PLC) specific for phosphatidylethanolamine (PtdEtn) in retinoic acid (RA) differentiated cells. These separate activations produced different molecular species of DAG or PtdOH. PtdOH was able to stimulate the Ca2+ dependent protein kinase C (PKC) by a mechanism which differed from the action of DAG. PtdOH did not induce the translocation of the PKC to the membrane. Moreover PtdOH, in contrast to DAG, prevented PKC degradation by inhibiting the enzymatic hydrolysis by m-calpain. These observations suggest that the stimulation of cells by agonists elicited the production of specific molecular species of lipid second messengers depending on the physiological status of the cells, and probably on the nature of the stimulus. It seems therefore likely that the generation of specific lipid second messengers may activate specific PKC isoforms resulting in a specific cellular response.

Animals↗

PubMed1996

Bupivacaine for postoperative analgesia following endoscopic sinus surgery.

This prospective study was conducted to examine pain after endoscopic sinus surgery (ESS). The hypothesis was that a long-acting anesthetic agent would result in patients experiencing less pain in the 24-hour postoperative period and therefore needing fewer oral analgesics. We randomized 100 patients undergoing ESS to receive either lidocaine (1% or 2%) with epinephrine or bupivacaine (0.25% or 0.5%) with epinephrine as an anesthetic and for a sphenopalatine block. Postoperative pain was assessed with a standard numeric pain assessment scale at baseline and at 2, 6, and 24 hours after surgery. The use of analgesics during this period was also documented. We compared the results between patients receiving bupivacaine and those receiving lidocaine, as well as between patients who required nasal packing and those who did not. We discovered that in general, pain after ESS was less severe than expected. We further found that the type of anesthetic used did not significantly affect postoperative pain; pain score changes and use of analgesics were similar between the two anesthesia groups. Postoperative pain was also similar between the "packing" and "no packing" groups. Although patients receiving packing had consistently lower increases in pain (and in fact many patients in this group had decreases in pain from baseline), none of the differences between group means was statistically significant.

Adult↗

PubMed1996

Characterization of major depression symptoms in multiple sclerosis patients.

Retrospective review of affective disturbances in 238 patients with multiple sclerosis (MS) seen over a 6-month period revealed: 1) 51 patients (22%) received pharmacologic treatment for depressive symptoms during or within 4 years of the study period, and 17 (7%) received treatment for rapid mood swings; 2) among the 51 depressed patients, response rate to medication was extremely high; 3) relapse of depressive symptomatology after discontinuation of medication was also high (17/29); 4) first episodes of major depression frequently occurred during periods of MS progression or exacerbation, but first episodes also occurred during periods of relative clinical stability; 5) suicidal ideation was common (12 patients), but only 1 patient had a history of attempted suicide; and 6) side effects were tolerable in most patients.

Adult↗

PubMed1996

Predictive value of IgG subclass levels for infectious complications in renal transplant recipients.

Renal allograft recipients are at risk to acquire infectious disease complications primarily after an intensified immunosuppressive therapy. In this study, serum levels of IgG, IgA, IgM and IgG subclasses were compared between transplant patients after different anti-rejection regimen and evaluated as possible predictive markers for infectious implications. Thirty-six renal transplant recipients in the early posttransplantation period were allocated into three subgroups: group 1 consisted of 15 subjects with good primary graft function standing under a basal triple drug immunosuppression; patients of group 2 (n = 9) had a very early acute rejection episode which was treated by high steroid doses and patients of group 3 (n = 12) required antithymocyte globulin (ATG) therapy for acute rejection. Immune parameters were studied 5 weeks after transplantation, when basal triple drug immunosuppression was continued in all patients. Twenty-three age-matched patients under chronic hemodialysis were recruited as a control group. Total IgG serum levels were reduced in transplant patients compared to dialysis subjects, whereas IgA and IgM levels were not altered. IgG subclass analysis revealed, that IgG1 levels were similar in stable transplant compared to chronic hemodialysis patients, but were significantly reduced in rejection patients after steroid pulses or ATG therapy. IgG3 levels were significantly reduced in all transplant recipients compared to dialysis patients without differences between the transplant subgroups. IgG2 and IgG4 subclass levels were similar in all studied subjects. IgG subclass abnormalities were paralleled by a reduction of lymphocyte subsets in rejection patients of groups 2 and 3, which may be the basis for an altered Ig class switching. Seven out of 36 studied transplant patients had severe infections in the early posttransplantation period with four cases of viral infections. Patients with infections had significantly lower IgG1 levels and CD4 positive lymphocyte numbers but similar total IgG levels compared to patients without infections. So IgG1 levels may be of value to predict the occurrence of infectious complications in renal allograft recipients in the early posttransplantation period.

Antilymphocyte Serum↗

PubMed1996

In vitro metabolism of atrazine, terbuthylazine, ametryne, and terbutryne in rats, pigs, and humans.

The in vitro metabolism of four s-triazine herbicides (atrazine, terbuthylazine, ametryne, and terbutryne) was studied using liver microsomes from rats, pigs, and humans. New HPLC methods with UV detection were developed for the analyses of the incubations. Principal phase I reactions were N-monodealkylation, hydroxylation of the isopropyl or tert-butyl moiety, and sulfoxidation of the substrates in all species. Bidealkylation, 2-hydroxylation, or cleavage of the tert-butyl moiety could not be found in this system. The sulfoxidation of the 2-methylthio-s-triazines exceeded catalysis of the other metabolic reactions by 3-4-fold in all species. In general, all species produced the same types of metabolites, but with species-specific differences in the ratios of the metabolites. Species-specific stereoselective formation of a new chiral isopropyl-hydroxylated metabolite from atrazine was investigated using chiral HPLC techniques. The stereoselective production of this metabolite was different in the different species, with S/R ratios of 76:24 in rats, 49:51 in pigs, and 28:72 in humans.

Animals↗

PubMed1996

Stable expression and coexpression of human cytochrome P450 oxidoreductase and cytochrome P450 1A2 in V79 Chinese hamster cells: sensitivity to quinones and biotransformation of 7-alkoxyresorufins and triazines.

V79 Chinese hamster cell lines were genetically engineered for the stable expression of human NADPH-cytochrome P450 oxidoreductase (CYPOR) alone or for the combined expression of CYPOR and human cytochrome P450 1A2 (CYP1A2). As determined by immunoblotting, the expression level of CYP1A2 in the latter cell line was found to be the same as in a previously constructed V79 cell line expressing CYP1A2 only. The heterologous expression of CYPOR in V79 cells resulted in increased sensitivity to quinone-type cytotoxins, e.g. duroquinone and menadione, that exert their toxicity primarily through the production of reactive oxygen species during redox cycling. The metabolic properties of the cell line expressing both CYPOR and CYP1A2 were characterized regarding dealkylation and deethylation of 7-alkoxyresorufins and sulfoxidation of the triazine derivatives ametryne and terbutryne, in comparison with the cell line expressing only CYP1A2. Increased CYPOR activity impaired the CYP1A2-dependent fluorometric resorufin assay, presumably by conversion of the 7-alkoxyresorufins and resorufin to their one-electron-reduced semiquinoneimine forms. The CYP1A2-dependent metabolism of the triazine derivatives ametryne and terbutryne was moderately enhanced by increased CYPOR activity. Interestingly, with CYPOR overexpression sulfoxidation was increased 2-3-fold, compared with N-deethylation, with a 1.3-1.9-fold increase. Thus, the level of CYPOR not only had an influence on CYP1A2 activity rates but also affected the relative proportions of metabolites in CYP1A2-specific metabolite profiles.

Animals↗

PubMed1996

Infection by Candida albicans inhibits apoptosis of human monocytes and monocytic U937 cells.

Infectious microorganisms can differently induce or inhibit apoptosis of immunocompetent effector and host cells. In this study we examined the influence of an infection by Candida albicans (C. albicans) on programmed cell death of monocytic U937 cells and human monocytes. Basal and tumor necrosis factor alpha (TNF-alpha)-induced DNA fragmentation of U937 cells was significantly inhibited by an infection with C. albicans. Enhanced apoptosis of U937 cells, induced by TNF-alpha, caused a diminished candidacidal activity of the effector cells, whereas inhibition of apoptosis by granulocyte-macrophage colony-stimulating factor (GM-CSF) was paralleled by an intensified host defense. Pretreatment of U937 cells or monocytes with the cyclooxygenase blocker indomethacin completely abolished the reduction of DNA fragmentation induced by the yeast. Studying the underlying mechanisms we found that C. albicans induced formation of prostaglandin E2 (PGE2) by U937. Exogenous administration of PGE2 down-regulated apoptosis of U937 or human monocytes to a similar extent as did fungal infection. Activation of protein kinase A by the cAMP analogue 8-bromo-cAMP inhibited U937 apoptosis, as did PGE2. On the other hand, rp-cAMP, a blocker of the cAMP-dependent signal transduction, restored and elevated DNA fragmentation levels down-regulated by C. albicans. U937 cells expressed the bcl-2 protein but the infection with fungi or PGE2 treatment did not increase proto-oncogene expression. Monocytic effector cells may therefore strengthen the defense against C. albicans by an autocrine feedback regulation via a PGE2-dependent, cAMP-transduced inhibition of apoptosis.

Apoptosis↗

PubMed1995

Phosphatidic acid activation of protein kinase C in LA-N-1 neuroblastoma cells.

Phosphatidic acid (PA), a hydrolytic product of phospholipase D activity, stimulated cytosolic protein kinase C (PKC) activity when LA-N-1 neuroblastoma cells in culture were treated with PA, without translocating the enzyme to the membrane. Treatment of cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) translocated and activated PKC in a dogmatic manner. Partially purified PKC activity derived from LA-N-1 neuroblastoma cells was stimulated by PA alone or in the presence of phosphatidylserine or TPA, without affecting [3H]phorbol dibutyrate binding, indicating that the site of action of PA was different from the phorbol ester or diacylglycerol binding site. These results suggest an unorthodox pattern of PKC stimulation mediated by PA which appears to be yet another mode of PA signal transduction.

Binding, Competitive↗

PubMed1995

Highly sensitive and specific high-performance liquid chromatographic analysis of 7-hydroxywarfarin, a marker for human cytochrome P-4502C9 activity.

The formation of 7-hydroxywarfarin in incubations of (S)-warfarin with human liver microsomes reflects their cytochrome P-4502C9 activity. This paper describes a rapid high-performance liquid chromatographic method for the determination of 7-hydroxywarfarin with high sensitivity, selectivity, and a simple sample clean-up procedure. Separation was achieved with a C18 reversed-phase column and quantification by fluorometric detection. The method employs an internal standard resulting in good accuracy and precision. The limit of detection is 150 fmol for 7-hydroxywarfarin.

Anticoagulants↗

PubMed1995

Phospholipids inhibit proteolysis of protein kinase C alpha by mM calcium-requiring calpain.

The alpha isoform of protein kinase C (PKC alpha) is rapidly hydrolyzed by mM Ca(2+)-requiring calpain (calcium-activated neutral proteinase) under cell-free conditions (Shea et al, 1994, FEBS Lett. 350:223). In the present study, we demonstrate that this hydrolysis is inhibited by phosphatidyl serine, diacylglycerol, phosphatidyl choline, phosphatidyl inositol, and phosphatidic acid. With the exception of phosphatidic acid, these phospholipids did not directly inhibit calpain activity as evidenced by degradation of [14C]azocasein, suggesting that the nature of inhibition of calpain-mediated PKC alpha degradation is due to an effect of phospholipids on PKC alpha conformation. These findings suggest that m calpain-mediated PKC alpha hydrolysis may be specifically minimized at the plasma membrane, and leave open the possibility that such a mechanism exists in situ. In addition, the unique inhibition of calpain activity by phosphatidic acid suggests the existence of a specific mechanism by which this phospholipid regulates PKC alpha activity.

Calpain↗

PubMed1995

Prostacyclin aerosol in an infant with pulmonary hypertension.

Prostacyclin aerosol (100 ng/kg.min) caused selective pulmonary vasodilation without causing systemic hypotension in an infant with idiopathic pulmonary hypertension. Cardiac index increased suggesting improved right ventricular function. CONCLUSION Aerosolized prostacyclin causes selective pulmonary vasodilation and may thereby improve systemic haemodynamics in infants with primary pulmonary hypertension. Because of the lack of known toxicity and the uncomplicated mode of administration it may be a useful alternative to inhaled nitric oxide.

Aerosols↗

PubMed1995

Late effects of anthracycline therapy in childhood in relation to the function of the heart at rest and under physical stress.

To evaluate the long-term effects of anthracyclines on the myocardium of the young child we examined 34 patients who had been treated with anthracyclines in childhood. In addition to anthracycline, the patients were treated with other potentially cardiotoxic substances within the framework of different protocols. The mean cumulative anthracycline dose was 128.6 mg/m2, the average age at onset of chemotherapy 4.2 years, and the time interval after discontinuation of treatment 9.0 years. The cardiological examination consisted of a physical examination, electrocardiography and echocardiography, including Doppler and bio-impedance cardiography. The patients were studied at rest and after physical exercise with a cycle ergometer test in a supine position. The results of the physical examination, the electrocardiogram at rest and the 24 h Holter monitoring were normal. The left ventricular enddiastolic diameter, shortening fraction, velocity of fibre shortening (VCF), the diastolic flow profile at the mitral valve level and the cardiac stroke volume at rest were also normal. However, the shortening fraction (SF) was below the margin of 2 standard deviations in two patients and the VCF in three patients. There was a significant reduction in septal thickness, (-1.4 SD, P < 0.0004), in the width of left ventricular posterior wall (-1.5 SD, P > 0.0002) and in the left ventricular myocardial mass (-0.76 SD, P = 0.0042). Physical working capacity was normal. Immediately after physical stress the expected rise of SF and VCF did not occur and the SF fell below the values at rest. In comparison to a healthy control group the SF and the VCF were markedly decreased (P > 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1995

Molecular species analysis of 1,2-diglycerides on phorbol ester stimulation of LA-N-1 neuroblastoma cells during proliferation and differentiation.

1,2-Diacyl-sn-glycerol (DAG) is a product of cell activation that has emerged as an important intracellular messenger whose primary function appears to be the activation of protein kinase C. They originate by the activation of phospholipases, which hydrolyze different phospholipids depending on the external stimulus and the nature of the cells, leading to the production of different molecular species. In the present study the quantitative changes in the total mass and the molecular species of DAG formed on phorbol ester (12-O-tetradecanoyl-phorbol 13-acetate) stimulation were investigated in proliferating and retinoic acid (RA)-differentiated human LA-N-1 cells. The TPA treatment of both cell types elicited an increase in the total amount of DAG. The increase was biphasic; i.e., an initial peak at 2-5 min was followed by a sustained increase that persisted for > 30 min. The analysis of the molecular species of DAG and phospholipids showed that in proliferating LA-N-1 cells, the DAG increase corresponds to the production of mainly saturated/monounsaturated (16:0-18:1, 18:0-18:1) and saturated/saturated (16:0-16:0, 16:0-18:0) species, suggesting that they originate essentially from the hydrolysis of phosphatidylcholine. In contrast, RA-differentiated cells responded to TPA treatment by increasing the level of saturated/polyunsaturated (16:1-22:6, 18:0-22:6, 16:0-20:4, 18:0-20:4) and monounsaturated/monounsaturated (18:1-18:1) species, suggesting mainly a phosphatidylethanolamine origin. These findings indicate that the treatment of LA-N-1 cells with TPA generates different molecular species of DAG depending on their physiological state. These observations suggest in turn that different phospholipases are activated by TPA in proliferating and RA-differentiated cells.

Cell Differentiation↗

PubMed1995

Chemopreventive activity of Oltipraz against N-nitrosobis(2-oxopropyl)amine (BOP)-induced ductal pancreatic carcinoma development and effects on survival of Syrian golden hamsters.

The synthetic dithiolethione Oltipraz has marked cancer chemopreventive and phase II enzyme inducing activity in various animal carcinogenesis models, but has not been examined in any animal models of ductal pancreatic cancer relevant to the human disease. The chemopreventive potential of Oltipraz on pancreatic tumor incidence and multiplicity was examined in the N-nitrosobis(2-oxopropyl)-amine (BOP)-induced ductal pancreatic adenocarcinoma model in Syrian hamsters. Animals were maintained on control semipurified diets or semipurified diets containing 300 and 600 mg/kg Oltipraz beginning 2 weeks prior to BOP initiation and throughout the 26 week study. Oltipraz at 300 mg/kg had no effect on the incidence or multiplicity of preneoplastic, neoplastic or metastatic lesions, while at 600 mg/kg dietary Oltipraz the incidence of pancreatic adenocarcinomas was reduced significantly (P < or = 0.05) compared to BOP-treated controls. Dietary Oltipraz at both doses had a significant influence on reducing mortality and morbidity in tumor-bearing animals with metastatic disease. At 26 weeks, total hepatic glutathione-S transferase (GST) activity and GST mu activity were elevated significantly in Oltipraz-treated animals, while total pancreatic GST activity was reduced, albeit not significantly. Serum lipase activity, a marker for pancreatic damage, exhibited a progressive decline in BOP-treated animals administered Oltipraz compared to BOP-treated controls at 12 weeks of the study; by week 26, lipase activity was comparable in all groups and reduced compared to activity at week 12. Positive nuclear immunostaining for the p53 tumor suppressor protein, a hallmark of human pancreatic cancer and a transient response to DNA damage, was observed in only a small percentage of BOP-induced pancreatic lesions and was not influenced Oltipraz administration. Further chemoprevention and pharmacologic studies of Oltipraz in relevant animal models of ductal pancreatic cancer could provide a foundation for future studies in human populations at potential risk for pancreatic cancer.

Animals↗

PubMed1995

Functional interaction between the human cytomegalovirus 86-kilodalton IE2 protein and the cellular transcription factor CREB.

The 86-kDa IE2 protein (IE86) of human cytomegalovirus (HCMV) has been described as a promiscuous transactivator of viral, as well as cellular, gene expression. Investigation of the mechanism used by IE86 to activate gene expression from the early UL112/113 promoter of HCMV revealed the existence of three binding sites for IE86 located between nucleotides -290 and -120 relative to the transcriptional start site (H. Arlt, D. Lang, S. Gebert, and T. Stamminger, J. Virol. 68:4117-4125, 1994). As shown previously, deletion of these target sites resulted in a reduction of IE86-mediated transactivation by approximately 70%. The remaining promoter, however, could still be stimulated about 40-fold, indicating the presence of an additional responsive element within these sequences. Here, we provide evidence that a binding site for the cellular transcription factor CREB can also act as a target for IE86 transactivation. By DNase I protection analysis, a binding sequence for CREB could be detected between nucleotides -78 and -56 within the respective promoter region. After in vitro mutagenesis of this CREB-binding site within the context of the entire UL112/113 promoter, a marked reduction in transactivation levels was evident. Moreover, when individual CREB-binding sites were positioned upstream of a minimal, TATA box-containing UL112/113 promoter, they were able to confer strong IE86 responsiveness, whereas a mutated sequence did not exert any effect. In far Western blot and pull-down experiments, a direct interaction of IE86 with the cellular transcription factor CREB could be observed. The in vivo relevance of this in vitro interaction was confirmed by using various GAL4 fusion proteins in the presence or absence of IE86 which revealed a strong activation only in the presence of both a GAL4-CREB fusion and IE86. This shows that at least one specific member of the ATF/CREB family of transcription factors is involved in mediating transactivation by the HCMV IE86 protein.

Base Sequence↗

PubMed1995

Endothelial inhibition of myofilament calcium response in intact cardiac myocytes.

Recent studies suggest that factors released by endothelial cells can modify contraction of isolated cardiac preparations. We compared the effects of 1) coronary effluent collected from Langendorff-perfused rat hearts and 2) cultured vascular endothelial cell superfusate on isolated fura 2-loaded rat ventricular cardiac myocytes. Coronary and cultured cell effluent produced similar effects. Isotonic contraction amplitude was reduced by 31.6 +/- 2.6 and 70.2 +/- 9.1%, respectively; myocyte diastolic length increased by 0.8 +/- 0.2 and 1.5 +/- 0.4 microns, and time to 50% relaxation fell by 6.2 +/- 1.8 and 10.1 +/- 2.0% (all P < 0.05; n = 29 and 15 myocytes, respectively). A small fall in the amplitude of the intracellular Ca2+ transient was observed (8.5 +/- 1.5 and 10.9 +/- 3.5%, respectively; both P < 0.01), insufficient to account for the reduction in twitch amplitude. In intact myocytes tetanized in the presence of thapsigargin, the steady-state myofilament response to Ca2+ was reduced by coronary and cultured cell effluent. These results suggest that both coronary endothelial cells in situ and cultured endothelial cells tonically release a factor(s) that reduces myofilament Ca2+ response.

Actin Cytoskeleton↗

PubMed1995

Prolonged akinetic mutism due to multiple sclerosis.

A 25-year-old woman with multiple sclerosis and an affective disorder probably secondary to MS presented with multiple neurological signs and symptoms suggestive of active MS, most prominently akinetic mutism. Spinal fluid analysis and MRI supported a diagnosis of active MS. SPECT and EEG were nonspecifically abnormal. After 6 weeks of severe akinetic mutism refractory to one ECT treatment and trials of steroids and stimulants, the patient recovered spontaneously over a 2-month period. An acute brainstem lesion seen on MRI may explain this patient's akinetic mutism.

Adult↗

PubMed1994

Minor groove contacts are essential for an interaction of the human cytomegalovirus IE2 protein with its DNA target.

The 86 kDa immediate early-2 protein (IE2, IE86) of human cytomegalovirus (HCMV) is a multifunctional polypeptide that can regulate gene expression both positively and negatively. In particular, it represses its own mRNA synthesis by binding directly to a sequence element, termed cis repression signal (CRS), that is located between the TATA box and the transcriptional start site of the major IE enhancer/promoter of HCMV. Here, we provide evidence that IE86, unlike most sequence-specific DNA-binding proteins, interacts primarily within the minor groove of the DNA helix. This was shown by hydroxyl radical and methylation interference assays. In addition, binding studies with inosine-substituted oligonucleotides which have an altered major groove morphology without changing the surface of the minor groove, confirmed the results obtained in interference analyses. This establishes IE86 as a member of a small group of DNA binding proteins that interact with A - T rich sequences within the minor groove and which also includes the TATA-box binding protein TBP. Remarkably, IE86 and TBP are able to bind simultaneously in an immediate vicinity at the major IE enhancer/promoter of HCMV. As minor groove binding proteins are known to bend DNA heavily this could contribute to the observed negative regulation of transcription by IE86.

Antigens, Viral↗