Biomedical subjects

M Voss

Publications and source records attributed to M Voss.

At least 37 records · Page 2Linked to original sources

PubMed2001

Mortality among women and men relative to unemployment, part time work, overtime work, and extra work: a study based on data from the Swedish twin registry.

OBJECTIVE: To examine mortality before 70 years of age among women and men relative to unemployment, part time work, overtime work, and extra work. Age, marital status, children, smoking and alcohol habits, use of sleeping pills and tranquilisers, stress, shift work, personality factors, and long lasting or serious illness were taken into account as potential confounding factors. METHODS: The study group comprised a subcohort of the Swedish twin registry, people born in 1926-58. Data were based on a postal questionnaire of 1973 and on information from the Swedish Causes of Death Registry. All subjects reporting a main occupation were selected, 9500 women and 11 132 men, and mortality from all causes during 1973-96 was analysed. The subjects were treated as a sample from the general population regardless of the twinning. RESULTS: Unemployment in 1973 among both women and men showed an association with increased mortality. The adjusted relative risk (RR) (95% confidence interval (95% CI)) was 1.98 (1.16 to 3.38), for women and 1.43 (0.91 to 2.25) for men. For the first 5 years of follow up, a threefold increase in risk was found for men (RR (95% CI) 3.29 (1.33 to 8.17)). The RR declined by time, but remained increased throughout the 24 year study period. In women overtime work of more than 5 hours a week was followed by an increased mortality rate (RR (95% CI) 1.92 (1.13 to 3.25)). A protective effect of moderate overtime work of a maximum 5 hours a week was shown for men (RR (95% CI) 0.58 (0.43 to 0.80)), whereas an increased mortality was indicated for part time work (RR (95% CI) 1.58 (0.91 to 2.77)) and extra work (work outside employment) of more than 5 hours a week (RR (95% CI) 1.29 (0.99 to 1.69)). CONCLUSION: Unemployment and some time aspects of work were associated with subsequent mortality, even when controlling for social, behavioural, work, and health related factors. The idea that losing a job may have less importance for women than for men is not supported by this study.

Cohort Studies↗

PubMed2001

Physical, psychosocial, and organisational factors relative to sickness absence: a study based on Sweden Post.

OBJECTIVE: To analyse incidence of sickness for women and men relative to potential aetiological factors at work-physical, psychosocial, and organisational. METHODS: The study group comprised 1557 female and 1913 male employees of Sweden Post. Sickness absence was measured by incidence of sickness (sick leave events and person-days at risk). Information on explanatory factors was obtained by a postal questionnaire, and incidence of sickness was based on administrative files of the company. RESULTS: Complaints about heavy lifting and monotonous movements were associated with increased risk of high incidence of sickness among both women and men. For heavy lifting, an odds ratio (OR) of 1.70 (95% confidence interval (95% CI) 1.22 to 2.39) among women, and OR 1.70 (1.20 to 2.41) among men was found. For monotonous movements the risk estimates were OR 1.42 (1.03 to 1.97) and OR 1.45 (1.08 to 1.95) for women and men, respectively. Working instead of taking sick leave when ill, was more prevalent in the group with a high incidence of sickness (OR 1.74 (1.30 to 2.33) for women, OR 1.60 (1.22 to 2.10) for men). Overtime work of more than 50 hours a year was linked with low incidence of sickness for women and men. Among women, 16% reported bullying at the workplace, which was linked with a doubled risk of high incidence of sickness (OR 1.91 (1.31 to 2.77)). For men, the strongest association was found for those reporting anxiety about reorganisation of the workplace (OR 1.93 (1.34 to 2.77)). CONCLUSIONS: Certain physical, psychosocial, and organisational factors were important determinants of incidence of sickness, independently of each other. Some of the associations were sex specific.

Adult↗

PubMed2001

Systemic and local immunosuppression in pancreatic cancer patients.

Pancreatic cancer is characterized by an extremely poor prognosis. For the development of more effective immunotherapies, the systemic and local immunological escape mechanisms need to be further elaborated. These mechanisms may include the secretion of immunosuppressive cytokines, the local hindrance of tumor-infiltrating lymphocytes (TILs), or the loss of the signal transducing CD3 zeta-chain of TILs. In this study, we have analyzed these parameters in 116 patients suffering from pancreatic ductal adenocarcinoma. Mean concentrations of interleukin (IL)-10 and transforming growth factor-beta1/2 were considerably higher than in control sera (P < 0.0001). Disseminated tumor cells were found in 16 of 39 cases. In 28 of 33 surgical specimens, TILs did not reach tumor cells in significant numbers, being "trapped" in the peritumoral tissues. We suggest this as a simple but highly effective tumor escape mechanism. In cases of a TIL/tumor cell contact, CD3 zeta was mostly lost. Overall, 27 of 33 surgical specimens, 9 of 19 peritumoral lymph nodes, and 13 of 25 peritoneal lavage specimens showed significant loss of CD3 zeta (P < 0.02). Elevated concentrations of IL-10/TGF-beta1/2 were, in all but one of three cases, correlated with a CD3 zeta loss in corresponding specimens. Patients with disseminated tumor cells also showed a CD3 zeta loss in all but two corresponding tumor specimens. These results present strong evidence for an active systemic immunosuppression in pancreatic cancer, as shown by elevated IL-10 and TGF-beta1/2 serum levels as well as the presence of disseminated tumor cells. Killing of tumor cells by potentially cytotoxic TILs is obviously suppressed by the prevention of a direct TIL/tumor cell contact and the inactivation of TILs, as shown by a severe loss of CD3 zeta. In addition to active immunization strategies, successful immunotherapies have to focus on restoring in vivo T-cell function to improve the almost always fatal prognosis of pancreatic cancer.

Adult↗

PubMed2001

Response of domestic geese to lentogenic and velogenic strains of Newcastle disease virus.

A total of 54 domestic white meat-type geese were included in vaccination/challenge trials to evaluate susceptibility to disease and humoral immune responses using the haemagglutination inhibition (HI) and virus neutralization (VN) tests against Newcastle disease (ND). Two groups of twenty geese, five weeks of age, were conjunctivally vaccinated with either 100 x 10(6) or 2.5 x 10(6) EID50 (egg infectious dose 50 per cent) per bird of live La Sota virus, respectively, and 14 geese remained unvaccinated. At 15 weeks of age all vaccinated geese and seven unvaccinated geese were subcutaneously injected with 0.5 ml of inactivated oil emulsion ND vaccine, whereas seven geese remained as negative controls. At an age of 20 weeks, all 54 geese were challenged with 10(8.0) EID50 per bird of the viscerotropic velogenic NDV strain Herts 33/56. Live virus application as well as the oil emulsion vaccine did not induce discernible clinical signs and have no detrimental effect on body weight gains. At days 1, 3, 5, 8, 13, 16, 20, 23 and 27 after the application of lentogenic vaccine pharyngeal and cloacal swabs were taken, after challenge samples were taken at days 2, 5 and 8. Lentogenic as well as velogenic virus were never reisolated. Low and shortlived antibody responses post vaccination were equally well measured in HI and VN tests. Only two out of seven unvaccinated but challenged geese developed signs of ND whereas all vaccinated/challenged geese remained normal but developed high to moderate levels of HI and VN antibodies. Since domestic geese do not readily excrete NDV's in detectable amounts and since they do not contain detectable amounts of the challenge virus fourteen days post challenge in their tissues the assumption is promoted that geese do not play a major role in the epidemiology of Newcastle disease.

Animals↗

PubMed2001

Changes in sickness absenteeism following the introduction of a qualifying day for sickness benefit--findings from Sweden Post.

AIMS: In 1993, a qualifying day without sickness benefit was introduced to the Swedish sickness benefit system. The aim of the present study is to investigate sickness absenteeism before and after the introduction of the qualifying day, in the light of conditions inside and outside working life. METHODS: The study was based on 1,952 female and 2,229 male employees of Sweden Post. Sickness absence was measured by sickness incidence one year before and one year after the introduction of the qualifying day (sick-leave events/person days at risk). Information about explanatory factors was collected by a postal questionnaire in 1994. RESULTS: A decrease in sickness incidence was observed after the introduction of the qualifying day as well as an increase in the mean duration of sick-leave events. The proportion of long-term sick-leave events (15-365 days) increased; among men this increase was also found in absolute terms. There were no suggestions of economy being an important determinant for reduced sickness incidence. Women with long-term or serious disease did not show a reduction of sickness incidence to the same extent as those without disease, and for men a coherent result was observed. Men with heavy lifting at work more often showed an increase in incidence compared to men without heavy lifting, and the same tendency was found for women. CONCLUSION: The reduction in sickness incidence following the introduction of the qualifying day was fairly independent of different work-related and non-work-related factors. The impact of the qualifying day differed depending on health status and the physical workload.

Adult↗

PubMed2000

Reactions of central neurons to peripheral thermal stimuli in the snail Helix pomatia L.

In Helix pomatia L. recordings have been made of 91 single neurons from the cerebral ganglia during peripheral thermal stimulation of the lip region. Temperatures ranged between 12 and 32 degrees C. Different reactions to thermal stimulation could be observed: hyperpolarisation (n=43), depolarisation (n=9), increasing frequency of action potentials (n=10), decreasing frequency of action potentials (n=3). A number of cells did not show any changes in neuronal activity (n=26). The assumption that distinct cell clusters are responsible for the processing of thermal stimuli had to be rejected since cells responding to peripheral thermal stimulation were found in all parts of the ganglia.

Journal Article↗

PubMed2000

Stimulation of phosphatidylinositol-4-phosphate 5-kinase by Rho-kinase.

The serine/threonine kinase Rho-kinase was recently identified as a downstream effector of the small GTPase Rho, mediating effects of Rho on the actin cytoskeleton. Also phosphatidylinositol 4,5-bisphosphate (PI(4,5)P(2)) has been implicated in the regulation of actin polymerization. As the synthesis of PI(4,5)P(2) has been suggested to be affected by Rho proteins, we investigated whether Rho-kinase is involved in the control of PI(4,5)P(2) levels. Overexpression of RhoA in HEK-293 cells increased phosphatidylinositol 4-phosphate (PI4P) 5-kinase activity and concomitantly enhanced cellular PI(4,5)P(2) levels, whereas overexpression of the Rho-inactivating C3 transferase decreased both PI4P 5-kinase activity and PI(4,5)P(2) levels. These effects of RhoA could be mimicked by overexpression of wild-type Rho-kinase and of the constitutively active catalytic domain of Rho-kinase, Rho-kinase-CAT. In contrast, a kinase-deficient mutant of Rho-kinase had no effect on PI4P 5-kinase activity. Importantly, the increase in PI4P 5-kinase activity and PI(4,5)P(2) levels by wild-type Rho-kinase, but not by Rho-kinase-CAT, was completely prevented by coexpression of C3 transferase, indicating that the effect of Rho-kinase was under the control of endogenous Rho. In cell lysates, addition of recombinant RhoA and Rho-kinase-CAT stimulated PI4P 5-kinase activity. Finally, the increase in PI(4,5)P(2) levels induced by both Rho-kinase-CAT and RhoA was reversed by the Rho-kinase inhibitor HA-1077. Our data suggest that Rho-kinase is involved in the Rho-controlled synthesis of PI(4,5)P(2) by PI4P 5-kinase.

Cell Line↗

PubMed2000

Biological effects of natural and recombinant mistletoe lectin and an aqueous mistletoe extract on human monocytes and lymphocytes in vitro.

Mistletoe lectin is thought to constitute the active principle in extract preparations from mistletoe, which are widely used as immunomodulators in adjuvant tumor therapy. However, no study exists which compares the immunological potency of different well-defined mistletoe lectin preparations on human immune cells. Therefore, in the present study the biological effects of an aqueous mistletoe extract, standardized for mistletoe lectin I (eML), the isolated natural mistletoe lectin (nML), and the recombinant form of this lectin (rML) on human peripheral blood monocytes and lymphocytes were compared with respect to cell viability and cytokine induction. After 48-hr incubation of peripheral blood mononuclear cells (PBMC) with rML, nML, and eML, a continuous concentration-dependent decrease in cell viability was found with an IC50 of about 3 ng/ml for rML and nML and 10 ng/ml for eML, respectively. This effect also was seen when isolated lymphocytes and monocytes were separately incubated with the lectin preparations. After incubation of PBMC and isolated monocytes of 5/10 blood donors with eML, an increase in cell viability was found at lectin concentrations between 10 and 1,000 pg/ml. This effect was not seen with the pure lectin preparations nML and rML. After 48-hr incubation of PBMC with rML, nML, and eML, induction of IL-1-beta, TNF-alpha, IL-2, IL-6, and IL-10 but not IFN-gamma was measured. For IL-1-beta it could be shown that cytokine induction took place at a broad lectin concentration range (0.1-100 ng/ml). Cytokine levels varied greatly in the PBMC cultures of the different blood donors. When monocytes were separately incubated with eML, nML, and rML for 48 hr, high levels of IL-1-beta were found. In contrast, in cultures of separated lymphocytes from the same donors only a minimal production of IL-1-beta and no production of IFN-gamma was found after incubation with rML, nML, and eML. It is concluded that there are quantitative differences in the immunomodulatory effects of the mistletoe lectin preparations on human monocytes and lymphocytes. Therefore, measurement of cell viability and cytokine induction may be a diagnostic laboratory tool to determine the immunological potency of various mistletoe preparations and may help to clarify the clinical benefit of therapies with these substances.

Adult↗

PubMed2000

Delay of the execution of rapid finger movement by magnetic stimulation of the ipsilateral hand-associated motor cortex.

We investigated the influence of focal transcranial magnetic stimulation (TMS) of the hand-associated motor cortex on the execution of ipsilateral finger-lifting movements in six humans. In a simple reaction time paradigm, suprathreshold TMS (1.6- to 2.1-fold of the response threshold determined at rest) was performed at intervals of 40, 70, 80, 90, and 100 ms after the auditory "go" signal. Movement onset was measured with an accelerometer. TMS delayed the execution of ipsilateral finger movement when the cortex stimulus preceded the onset of the intended movement by about 25-65 ms. Taking the corticomuscular conduction times to the activated muscles into account, TMS suppressed the output from the motor cortex in a period 6-45 ms after the contralateral motor cortex was stimulated. Such timing would be compatible with an interhemispheric inhibition similar to the previously described ipsilateral inhibition of ongoing tonic motor activity. The delay of the movement was 40 ms. The function of the neuronal structures mediating interhemispheric inhibition might be to suppress the coactivation of the other hand during unilateral finger movements within bimanual motor tasks.

Adult↗

PubMed2000

The VP2 variable region of African and German isolates of infectious bursal disease virus: comparison with very virulent, "classical" virulent, and attenuated tissue culture-adapted strains.

11 African and two German IBDV strains isolated in the mid '80s from field outbreaks in vaccinated and unvaccinated chicken flocks displayed features of very virulent (vv) IBDV strains. The sequence data of the VP2 variable region and phylogenetic analysis confirm that these strains can be grouped within vv IBDV strains which appeared at the same time on the three continents Africa, Asia, and Europe. Strain Cu-1wt, responsible for severe IBD outbreaks in Germany 13 years earlier, showed some relatedness to these strains, but also significant differences at the genomic level, even though this strain has also features of the vv IBDV strains.

Africa↗

PubMed2000

Intraoperative amiodarone as prophylaxis against atrial fibrillation after coronary operations.

BACKGROUND: New onset of atrial fibrillation is a frequent complication after coronary artery bypass grafting and is a major cause of postoperative morbidity. Preoperative oral treatment with amiodarone hydrochloride has been shown to be efficacious as prophylaxis. The present study investigated whether intraoperative use of intravenous amiodarone has a preventive effect on the incidence of atrial fibrillation after coronary revascularization. METHODS: In a prospective study, 150 consecutive patients (mean age, 63 +/- 8 years; 132 men and 18 women) undergoing coronary artery bypass grafting were randomly assigned to one of three groups. Two groups received different doses of intravenous amiodarone (group I, 300-mg bolus and 20 mg x kg(-1) x day(-1) for 3 days; group II, 150-mg bolus and 10 mg x kg(-1) x day(-1) for 3 days) after aortic cross-clamping and one group, placebo (group III). Continuous electrocardiographic online monitoring was performed for 10 days. Arrhythmias were analyzed with respect to type, frequency, duration, and clinical relevance. RESULTS: New onset of atrial fibrillation occurred in 24% of patients in group I, 28% in group II, and 34% in group III (p = not significant). Atrial fibrillation with a rapid ventricular response (>120 beats per minute) was significantly more frequent in the control group (group I, 14%; group II, 24%; group III, 32%; p < 0.05, group I versus group III) and appeared significantly earlier (group I, day 4.3 +/- 2.5; group II, day 4.8 +/- 2.9; group III, day 2.6 +/- 1.3; p < 0.05, group III versus groups I and II). Temporary atrial pacing because of bradycardia (<60 beats per minute) was necessary significantly more often in group I (group I, 48%; group II, 40%; group III, 28%; p < 0.05, group I versus group III). Early mortality rate (group I, 4%; group II, 2%; group III, 4%), rate of perioperative complications (group I, 14%; group II, 20%; group III, 14%), and duration of hospital stay (group I, 14.0 days; group II, 14.4 days; group III, 14.7 days) were not different between groups. CONCLUSIONS: Intraoperative prophylactic use of amiodarone does not prevent new onset of atrial fibrillation in patients undergoing coronary artery bypass grafting and had no effect on outcome. Therefore, intraoperative prophylactic treatment with amiodarone at the tested doses does not appear to be justified.

Amiodarone↗

PubMed2000

Suramin inhibits proliferation of human arterial smooth muscle cells in vitro: potential drug for prevention of restenosis by local drug delivery.

PURPOSE: Suramin is known to inhibit proliferation of various tumor cells. This study was performed to investigate the effect of suramin on proliferating human arterial smooth muscle cells (HASMC) and thus to examine its suitability for the prevention of restenosis. METHOD: Proliferation of HASMC was stimulated with human whole blood serum (HWBS), as well as with platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF). Proliferation was assessed by measuring DNA synthesis and cell viability was assessed by measuring mitochondrial activity. RESULTS: Suramin exerted a strong attenuating effect on the proliferation stimulators HWBS, PDGF, and bFGF. A suramin concentration of 0.5 mmol/L, which is approximately twice the dosage used for systemic application, was sufficient for complete neutralization of proliferation stimulation by 10% HWBS added to the cell culture medium. CONCLUSION: The authors' data demonstrate a strong proliferation inhibiting effect of suramin on HASMC in vitro. Because it is known to interact not only with one but with a multitude of relevant growth factors, these results make suramin a most interesting substance for local application for prevention of hyperplastic neointima formation.

Arteries↗

PubMed2000

[Knowledge of professional rules of ethics among professional nurses].

During recent years numerous publications on ethical issues appeared in German nursing literature. Nursing theorists repeatedly refer to the Code of Ethics of the International Council of Nursing (ICN). The implementation of codes of ethics is discussed as an indispensable stage within the development of independent nursing ethics. However, it is not clear whether nurses in Germany know about the ICN Code of Ethics or other codes of ethics. The authors' objective is to learn more about how much is known about codes of ethics by practical nurses in four selected hospitals. In addition, it is of interest to know, which advantages nurses might associate with codes of ethics and secondly from which sources nurses prefer to receive ethical education. The study shows that only 25% of the participants know about codes of ethics. It also reveals that further education offered by hospitals or the basic nursing education are seen as the most important source of information related to ethics. The major advantage of codes of ethics seen by the participants is to provide guidance in the decision-making process of ethical dilemma situations in nursing. Secondly the Code of Ethics is regarded as a useful framework to define obligations and rights of nurses in the relationship with patients and relatives. The results of the study indicate that the ICN Code of Ethics is practically unknown among nurses and should be discussed more extensively by practical nurses and nursing theorists.

Attitude of Health Personnel↗

PubMed2000

Value of endoscopic ultrasound guided fine needle aspiration biopsy in the diagnosis of solid pancreatic masses.

AIM: To assess the feasibility and diagnostic accuracy of endoscopic ultrasound guided fine needle biopsy (EUS-FNAB) in patients with solid pancreatic masses. METHODS: Ninety nine consecutive patients with pancreatic masses were studied. Histological findings obtained by EUS-FNAB were compared with the final diagnosis assessed by surgery, biopsy of other tumour site or at postmortem examination, or by using a combination of clinical course, imaging features, and tumour markers. RESULTS: EUS-FNAB was feasible in 90 patients (adenocarcinomas, n = 59; neuroendocrine tumours, n = 15; various neoplasms, n = 6; pancreatitis, n = 10), and analysable material was obtained in 73. Tumour size (>/= or < 25 mm in diameter) did not influence the ability to obtain informative biopsy samples. Diagnostic accuracy was 74.4% (adenocarcinomas, 81.4%; neuroendocrine tumours, 46.7%; other lesions, 75%; p<0.02). Overall, the diagnostic yield in all 99 patients was 68%. Successful biopsies were performed in six patients with portal hypertension. Minor complications (moderate bleeding or pain) occurred in 5% of cases. CONCLUSIONS: EUS-FNAB is a useful and safe method for the investigation of pancreatic masses, with a high feasibility rate even when lesions are small. Overall diagnostic accuracy of EUS-FNAB seems to depend on the tumour type.

Adenocarcinoma↗

PubMed2000

Neurophysiological and behavioral responses to olfactory stimuli in the snail Helix pomatia L.

Some aspects of olfactory sensitivity in the pulmonate Helix pomatia L. were studied by means of neurophysiological and behavioral methods. Single fiber recordings were carried out in the olfactory nerve of the posterior tentacles. Olfactory stimulations with different odors were performed by means of a continuous air stream. The order of neuronal sensitivity to different odors was as follows: ethanol > or = ethyl acetate > pentanol > hexanol > octanol > or = diethyl malonate > vanillin. Furthermore, the results revealed a relative specificity for some substances. A comparison between neurophysiological and behavioral data shows that those substances, which cause the highest increases in impulse frequency, also evoke a behavioral avoidance reaction.

Animals↗

PubMed1999

Phospholipase D stimulation by receptor tyrosine kinases mediated by protein kinase C and a Ras/Ral signaling cascade.

Stimulation of phospholipase D (PLD) in HEK-293 cells expressing the M(3) muscarinic receptor by phorbol ester-activated protein kinase C (PKC) apparently involves Ral GTPases. We report here that PKC, but not muscarinic receptor-induced PLD stimulation in these cells, is strongly and specifically reduced by expression of dominant-negative RalA, G26A RalA, as well as dominant-negative Ras, S17N Ras. In contrast, overexpression of the Ras-activated Ral-specific guanine nucleotide exchange factor, Ral-GDS, specifically enhanced PKC-induced PLD stimulation. Moreover, recombinant Ral-GDS potentiated Ral-dependent PKC-induced PLD stimulation in membranes. Epidermal growth factor, platelet-derived growth factor, and insulin, ligands for receptor tyrosine kinases (RTKs) endogenously expressed in HEK-293 cells, apparently use the PKC- and Ras/Ral-dependent pathway for PLD stimulation. First, PLD stimulation by the RTK agonists was prevented by PKC inhibition and PKC down-regulation. Second, expression of dominant-negative RalA and Ras mutants strongly reduced RTK-induced PLD stimulation. Third, overexpression of Ral-GDS largely potentiated PLD stimulation by the RTK agonists. Finally, using the Ral binding domain of the Ral effector RLIP as an activation-specific probe for Ral proteins, it is demonstrated that endogenous RalA is activated by phorbol ester and RTK agonists. Taken together, strong evidence is provided that RTK-induced PLD stimulation in HEK-293 cells is mediated by PKC and a Ras/Ral signaling cascade.

Bacterial Proteins↗

PubMed1999

Immunological escape mechanisms in pancreatic carcinoma.

Malignancies have developed several strategies to evade immune surveillance. We have investigated pancreatic cancer cell lines and pancreatic cancer surgical specimens to evaluate possibilities of tumor escape in the Fas system, and local immune suppression. Despite Fas expression the majority of cell lines was resistant to Fas-mediated apoptosis. The Fas-associated phosphatase-1 is a strong candidate to confer Fas resistance in pancreatic cancer cells. In addition, all investigated pancreatic cancer cell lines and cancer specimens expressed Fas ligand. Fas ligand was functional in cancer cell lines as shown by coculture assays of pancreatic cancer cell lines with Jurkat cells as targets. Additional local immune suppression was demonstrated by loss of T-cell receptor/CD3-zeta chain of pancreatic cancer infiltrating T-lymphocytes. We conclude that these tumor escape mechanisms may contribute to the poor prognosis of pancreatic cancer but also represent targets for new treatment modalities.

Adenocarcinoma↗

PubMed1999

A role for rho-kinase in rho-controlled phospholipase D stimulation by the m3 muscarinic acetylcholine receptor.

Stimulation of phospholipase D (PLD) by membrane receptors is now recognized as a major signal transduction pathway involved in diverse cellular functions. Rho proteins control receptor signaling to PLD, and these GTPases have been shown to directly stimulate purified recombinant PLD1 enzymes in vitro. Here we report that stimulation of PLD activity, measured in the presence of phosphatidylinositol 4,5-bisphosphate, by RhoA in membranes of HEK-293 cells expressing the m3 muscarinic acetylcholine receptor (mAChR) is phosphorylation-dependent. Therefore, the possible involvement of the RhoA-stimulated serine/threonine kinase, Rho-kinase, was investigated. Overexpression of Rho-kinase and constitutively active Rho-kinase (Rho-kinase-CAT) but not of kinase-deficient Rho-kinase-CAT markedly increased m3 mAChR-mediated but not protein kinase C-mediated PLD stimulation, similar to overexpression of RhoA. Expression of the Rho-inactivating C3 transferase abrogated the stimulatory effect of wild-type Rho-kinase, but not of Rho-kinase-CAT. Recombinant Rho-kinase-CAT mimicked the phosphorylation-dependent PLD stimulation by RhoA in HEK-293 cell membranes. Finally, the Rho-kinase inhibitor HA-1077 largely inhibited RhoA-induced PLD stimulation in membranes as well as PLD stimulation by the m3 mAChR but not by protein kinase C in intact HEK-293 cells. We conclude that Rho-kinase is involved in Rho-dependent PLD stimulation by the G protein-coupled m3 mAChR in HEK-293 cells. Thus, our findings identify Rho-kinase as a novel player in the receptor-controlled PLD signaling pathway.

Cell Membrane↗