Elevated K(+) induces myristoylated alanine-rich C-kinase substrate phosphorylation and phospholipase D activation in glomerulosa cells

Elevated extracellular potassium concentrations ([K(+)](e)) are known to stimulate aldosterone secretion from adrenal glomerulosa cells in vivo and in vitro. The mechanism is thought to involve depolarization-elicited activation of voltage-dependent calcium channels and an increase in calcium influx. Until now protein kinase C (PKC) was thought not to play a role in the steroidogenic response to elevated [K(+)](e). In this report, we provide evidence in bovine adrenal glomerulosa cells to suggest that elevated [K(+)](e) increases PKC activity, as shown by an enhancement in the phosphorylation of myristoylated alanine-rich C-kinase substrate (MARCKS). Elevated [K(+)](e)-induced MARCKS phosphorylation was delayed and transient and was not the result of a local production of angiotensin II (AngII). MARCKS phosphorylation in response to elevated [K(+)](e) was not accompanied by phosphoinositide hydrolysis but was inhibited by a selective PKC inhibitor. Elevated [K(+)](e) also activated phospholipase D (PLD) in a delayed but sustained manner. We propose that the observed PLD activation mediates the elevated [K(+)](e)-induced MARCKS phosphorylation via PKC, although other factors may modulate this phosphorylation event.

[B-Flow: sonographic assessment and therapy for femoral artery pseudoaneurysm]

PURPOSE

To evaluate the diagnostic accuracy of femoral artery pseudoaneurysm by B-flow, a new ultrasound method and the outcome of compression treatment.

MATERIAL AND METHODS

700 patients with radiological interventions (300 DSA, 355 PTA, 45 thrombolysis) have been examined by vascular ultrasound for possible bleeding at the puncture site to rule out pseudoaneurysms. The new B-flow ultrasound with a multi-frequency probe was used besides color-coded Doppler (CCD) and power Doppler (PD).

RESULTS

No pseudoaneurysm was found in patients with diagnostic angiography and thrombolysis. In 25 of 355 patients a pseudoaneurysm was detected after PTA in 8 of them in the common and in 17 in the superficial femoral artery. The diameters were 1.5 to 4.5 cm, 3 cm on average. By ultrasound compression treatment of 20 minutes on the average 23 out of 25 pseudoaneurysms were occluded without any further complication. In B-flow the lesion of the vessel wall, the flow in the fistula and in the sack of the pseudoaneurysm were better demonstrated and without artifacts compared to both other methods. This makes treatment by compression much easier, first of all because remaining flow phenomena and the progression of intracavitary thrombosis can be controlled.

CONCLUSION

The newly developed B-flow detects both slow and fast flow phenomena. Visualisation of the fistula canal and the aneurysm sack is more reliable and examiner-independent than other Doppler methods such as CCD and PD. This allows better compression treatment of the fistula canal.

[Low-dose thrombolysis using rt-Pa in extensive peripheral vascular occlusion]

PURPOSE

To evaluate the efficacy of intra-arterial thrombolysis by rt-PA in acute and subacute extensive peripheral vascular occlusion.

MATERIAL AND METHODS

100 patients with acute and subacute occlusion of peripheral arteries were treated by catheter thrombolysis using 20 mg of rt-PA over a period of 20-24 hours. In all cases the occlusion extended to more than 20 cm and two stages of the extremity were involved. In 80 patients the original vessels (69/80 by thrombosis, 11/80 by embolization) and in 20 cases the femoro-popliteal bypass vessel was occluded. A catheter was inserted into the thrombus into which rt-PA and heparin were separately infused by two injectors. Heparin was given in a dose of 800-1000 U/h depending on the continuously monitored PTT levels. A control angiography was performed after 10 mg of rt-PA. After successful thrombolysis either PTA or aspiration thrombectomy was performed, if necessary, to reestablish a nearly normal vascular lumen. Open arteries of the thigh and at least one main vessel of lower leg was considered as success.

RESULTS

Recanalization of the original vessels was successfully by thrombolysis, PTA or aspiration thrombectomy in 68/80 [85%] cases. Thrombolysis and PTA reestablished a normal lumen of the bypass vessel in 11/20 [65%] and in 6 more cases a recanalization with minor stenosis. In 13/15 patients with critical ischemia, thrombolysis probably helped to avoid amputation by reopening smaller collateral arteries. Bleeding at the puncture site, as a complication of thrombolysis, was the reason for stopping therapy in three cases. There was no retroperitoneal or cerebral bleeding. After successful thrombolysis, reocclusion occurred in 15 patients within one year, only in five cases amputation was necessary.

CONCLUSION

Extensive occlusion of peripheral arteries or of a femoro-cural bypass can be successfully treated by low dose rt-PA thrombolysis with a low complication rate. Even partial reopening may prevent amputation.

[3D vascular imaging with power mode in planning and controlling percutaneously implanted abdominal aortic stent grafts]

PURPOSE

Evaluation of the reliability of vascular ultrasound with power mode and 3D-power mode for preinterventional planning before endovascular treatment of abdominal aortic aneurysms and postoperative follow-up after endografting.

MATERIAL AND METHOD

A new real-time 3D technique with power mode flow imaging was used in a prospective study of 75 patients with infrarenal aortic aneurysms, in 25 cases before and in 50 cases after stentgraft implantation. The results of vascular ultrasound with color-coded duplex sonography (CCDS), power mode and 3D power mode were compared with CTA and DSA in all cases.

RESULTS

Only the length and diameter of the aneurysm could be reliably measured by sonography. Additional 3D reconstructions could show flow parameters in the aneurysm more clearly, but imaging of the proximal and distal anchoring zone was only achieved insufficiently. After stentgraft implantation, possible complications like thrombus formation in the graft (4/50) and endoleaks (15/50) were clearly seen by power sonography. 9 anchoring leaks and 6 side-branch endoleaks were found. 3D power mode made localizing and imaging of aneurysm reperfusion easier. Detection of the origin of side-branch endoleaks was achieved only by DSA. Stent frame fractures (4/50) were difficult to see by ultrasound.

CONCLUSIONS

Vascular ultrasound with power mode and 3D power mode makes the imaging of complications after endoaortic stentgraft implantation like endoluminal thrombus formation or endoleaks and the documentation of aneurysm reperfusion easier compared to CCDS. 3D reconstructions show the dimensions of the aneurysm but are not able to substitute CTA and DSA with measuring catheter for preinterventional planning.

[Diagnosis of pre-occlusive stenosis of the internal carotid artery by power mode ultrasound]

PURPOSE

To evaluate the accuracy of power mode (PM) vascular ultrasound in preocclusive (> 90%) stenosis of the extracranial internal carotid artery (ICA) compared to other diagnostic methods and to operative findings.

MATERIAL AND METHODS

50 patients with preocclusive stenosis have been examined in a prospective study by power mode and color flow duplex ultrasound, by triplane aortic arch and four plane selective DSA. In 11 cases a MR angiography (time-of-flight) was available. Diagnostic findings were compared to operative results.

RESULTS

There was an agreement in findings in 50/50 patients (100%) for selective DSA, in 47/50 (94%) for power mode ultrasound, in 38/50 (76%) for aortic arch DSA, in 31/50 (62%) for color flow duplex ultrasound, and in 5/11 for MR angiography. In contrast to all other methods, ultrasound showed best the true extent of non-calcified atheromatous plaques. In extended vascular calcifications or kinking, however, only parts of the lumen of the vessel could be demonstrated.

CONCLUSION

Power mode ultrasound shows preocclusive stenosis of the ICA in a faster and more simple way than color flow duplex ultrasound and has diagnostic results near to those of selective DSA. It improves preoperative diagnostic screening.

Effects of angiotensin II and adrenocorticotropic hormone on myristoylated alanine-rich C-kinase substrate phosphorylation in glomerulosa cells

Angiotensin II (AngII) is thought to stimulate aldosterone secretion from bovine adrenal glomerulosa cells in part via activation of protein kinase C (PKC), while adrenocorticotropic hormone (ACTH) functions through increases in intracellular cAMP levels and calcium influx. Rather than using invasive homogenization techniques as in previous studies, we chose to monitor PKC activity in intact glomerulosa cells in situ by measuring the phosphorylation of the endogenous PKC substrate, myristoylated alanine-rich C-kinase substrate (MARCKS). AngII enhanced MARCKS phosphorylation in a rapid, sustained manner; whereas ACTH induced a rapid and sustained inhibition of MARCKS phosphorylation. Studies using pharmacological agents to mimic various signals indicated that the AngII-induced MARCKS phosphorylation was due to PKC activation, and the ACTH-elicited decrease was mediated by increases in calcium influx rather than cAMP production. We propose that changes in the phosphorylation state of MARCKS, an actin-binding protein, may contribute to cytoskeletal rearrangements involved in steroidogenesis.

Sustained phospholipase D activation is associated with keratinocyte differentiation

Our previous results and data in the literature have suggested a potential role for phospholipase D (PLD) in the regulation of epidermal keratinocyte growth and differentiation. Therefore, we investigated the effect of agents reported to modulate keratinocyte growth and differentiation on PLD activation. The purported protein kinase C (PKC) 'inhibitor', staurosporine (Stsp), has been reported to activate PKC in keratinocytes, eliciting many of the same effects as active tumor promoters such as 12-O-tetradecanoylphorbol-13-acetate (TPA). Stsp also induces a programmed pattern of differentiation similar to that seen in keratinocytes in vivo; TPA, on the other hand, appears to preferentially elicit markers consistent with late (granular) differentiation. In contrast, bradykinin is reported to stimulate keratinocyte proliferation. We found that these three agents had different effects on PLD activation in primary mouse epidermal keratinocytes. TPA increased PLD activity acutely and in a sustained fashion. In contrast, Stsp did not acutely activate PLD and inhibited acute TPA-induced activation of PLD. However, treatment of keratinocytes with Stsp for longer time periods (3-5 h) induced sustained PLD activation and this long-term effect was additive with that of TPA. Bradykinin activated PLD acutely but transiently. Both TPA and Stsp increased transglutaminase activity, a marker of late differentiation, whereas bradykinin had little or no effect on either cell proliferation or transglutaminase activity. These results suggest that a sustained activation of PLD is associated with the induction of keratinocyte differentiation. We hypothesize that PLD activity mediates late keratinocyte differentiation through generation of diacylglycerol and activation of specific PKC isoforms. Furthermore, we propose that the profound and immediate TPA-induced stimulation of PLD activity 'drives' the keratinocytes to late differentiation steps. However, the less efficacious (and more gradual) sustained activation of PLD by Stsp may allow a patterned differentiation more like that observed in skin.

A potential role for ceramide in the regulation of mouse epidermal keratinocyte proliferation and differentiation

We have previously determined that sustained phospholipase D (PLD) activation is associated with differentiation induction in primary mouse epidermal keratinocytes. We therefore investigated the effect of two bacterial PLD on keratinocyte proliferation and differentiation. We found that Streptomyces sp. PLD was much less potent at inhibiting proliferation than S. chromofuscus PLD, with a half-maximal inhibitory concentration of 0.05 versus less than 0.001 IU per ml for S. chromofuscus PLD. Similarly, S. chromofuscus PLD stimulated transglutaminase activity more effectively and potently than S. sp. PLD. When we examined the formation of products by the two PLD, we found that the S. sp. PLD showed higher activity at all concentrations. Whereas the PLD from S. sp. is relatively inactive on sphingomyelin, S. chromofuscus PLD is known to hydrolyze both glycerophospholipids and sphingomyelin. Based on recent data indicating a role for ceramide in regulating cell growth and differentiation, we hypothesized that the ability of S. chromofuscus PLD to hydrolyze sphingomyelin might underlie its greater potency. Therefore, we examined the effect of exogenous sphingomyelinase and synthetic ceramides on DNA synthesis. We found that sphingomyelinase exhibited a potent concentration-dependent effect on [3H]thymidine incorporation, much like S. chromofuscus PLD. Synthetic cell-permeable ceramides (C6- and C2-ceramide) also concentration dependently inhibited DNA synthesis, with a half-maximal inhibitory concentration of approximately 12 microM. Finally, we obtained evidence suggesting that ceramide is generated in response to a physiologically relevant agent, because tumor necrosis factor-alpha, a known effector of sphingomyelin turnover in other systems and a cytokine that is produced and released by keratinocytes, increased ceramide levels in primary epidermal keratinocytes.

[Cystic degeneration of the adventitia of the popliteal artery: ultrasound angiography-aided puncture]

A filiform stenosis of the popliteal artery was examined by sonography and the reason for the cystic lesion in the arterial wall was found to be an uncommon type of cystic degeneration of the adventitia. The narrow lumen could be demonstrated by sonography and the lesion was punctured under ultrasound control. A viscous secretion was removed and the patient's claudication was cured without recourse to surgery.

[Incidence of primary malignant lesions in clinically benign teratoma: on the problem of adequate surgical procedure]

The Problem of an Adequate Surgical Approach: Frequency of malignant teratomas is, according to the literature, 2%-10%. Examining 194 own cases (1983-1993) it was 1.5%. We found one squamous cell carcinoma (0.5%). Additionally we found 2 immature teratomas (1%). We point out the different biological behaviour of malignant mature teratomas and immature teratomas. We agree with the majority of authors that the method of choice is the intact removal of all teratomas without iatrogen rupture or contamination of the abdominal cavity by contents of the teratoma. This adequate surgical procedure can and should be performed by laparotomy or laparoscopy with endobag. The often practised method of cutting open the cyst during laparoscopy, sucking off the contents or cutting the teratoma into pieces, has been proven to lead to implantation and worsening the prognosis in case of a malignant teratoma. Even the rinsing of the abdominal cavity, usually carried out with this method, could not compensate always for the disadvantage of this "dirty" endoscopical method compared with usual oncological standards. This is pointed out by case reports in the literature and the first analysis of a German survey with early-follow-up of 192 laparoscopically managed ovarian malignancies [11a]. The principle of intact removal of every teratoma should again be kept in mind.

Unusual presentation of Takayasu arteritis with cardiac involvement and imitation of juvenile arteriosclerosis. A case report

A twenty-five-year-old Caucasian man with Takayasu arteritis, who was formerly diagnosed as suffering from premature arteriosclerosis, is described. Necropsy disclosed involvement of the entire aorta and its major branches, the pulmonary arteries, the coronary arteries, the intramyocardial arteries, and the heart valves, a combination hitherto not described. Literature concerning heart involvement in Takayasu arteritis is reviewed, and the differential diagnosis is discussed.

Effect of garlic on platelet aggregation in patients with increased risk of juvenile ischaemic attack

A platelet-inhibiting effect is described for garlic. In this double-blind, placebo-controlled study on 60 voluntary subjects with cerebrovascular risk factors and constantly increased platelet aggregation it was demonstrated that the daily ingestion of 800 mg of powdered garlic (in the form of coated tablets) over 4 weeks led to a significant inhibition of the pathologically increased ratio of circulating platelet aggregates and of spontaneous platelet aggregation. The ratio of circulating platelet aggregates decreased by 10.3%, from 1.17 +/- 0.08 to 1.05 +/- 0.11 (P < 0.01), and spontaneous platelet aggregation by 56.3%, from 40.7 +/- 23.3 to 17.8 +/- 23.2 degrees (P < 0.01) during the garlic phase. There were no significant changes in the placebo group. The parallel group comparison (garlic versus placebo) revealed a significantly different ratio of circulating platelet aggregates after 4 weeks of treatment (P < 0.05). After the 4-week wash-out phase the values increased again to 1.19 +/- 0.32 and 34.9 +/- 28.7 degrees, reaching the initial values (run-in phase prior to the ingestion of garlic). Since garlic is well tolerated it would be worth testing it in a controlled clinical trial for usefulness in preventing disease manifestations associated with platelet aggregation.

Effects of garlic coated tablets in peripheral arterial occlusive disease

For the first time, a weak clinical efficacy of a 12-week therapy with garlic powder (daily dose, 800 mg) is demonstrated in patients with peripheral arterial occlusive disease stage II. The increase in walking distance in the verum group by 46 m (from 161.0 +/- 65.1 to 207.1 +/- 85.0 m) was significantly higher (P < 0.05) than in the placebo group (by 31 m, from 172.0 +/- 60.9 to 203.1 +/- 72.8). Both groups received physical therapy twice a week. The diastolic blood pressure, spontaneous thrombocyte aggregation, plasma viscosity, and cholesterol concentration also decreased significantly. Body weight was maintained. It is quite interesting that the garlic-specific increase in walking distance did not appear to occur until the 5th week of treatment, connected with a simultaneous decrease in spontaneous thrombocyte aggregation. Therefore, garlic may be an appropriate agent especially for the long-term treatment of an incipient intermittent claudication.

Influence of garlic powder on cutaneous microcirculation. A randomized placebo-controlled double-blind cross-over study in apparently healthy subjects

In a randomized placebo-controlled double-blind cross-over study it could be shown that 5 h after the administration of garlic powder (Kwai, Sapec; total dose of 900 mg garlic powder) a significant increase in capillary skin perfusion by 55% occurs in the healthy volunteers. Placebo did not cause any changes. The difference between the two study phases is also significant. The increased erythrocyte velocity results from vasodilation of precapillary arterioles which increases diameter of erythrocyte column by an average of 8.6%. Simultaneously inflow of interstitial fluidity accompanied by a significant decrease in haematocrit and plasma viscosity occurs (rheoregulation).

Protease Do is essential for survival of Escherichia coli at high temperatures: its identity with the htrA gene product

The DNA encoding protease Do was isolated from an E. coli genomic DNA library in lambda gt11, and cloned into a Bluescript plasmid. The cells transformed with the recombinant plasmid were able to overproduce protease Do and grew normally. A mutant lacking the protease activity was also isolated by interrupting the chromosomal DNA with the kan gene. The mutant showed a prolonged lag period and reduced ability to degrade cell proteins as compared to its wild type. Moreover, they were unable to survive at high temperatures, similarly to the htrA mutants. These results suggest that protease Do may play an important role in the intracellular protein breakdown and is essential for survival at high temperatures. Identity of protease Do with the htrA gene product is discussed.

Induction of protease La under stress and its effect on intracellular proteolysis in Escherichia coli

Induction of protease La was found to increase to higher extent in E. coli that had been treated with canavanine for longer period. However, hydrolysis of canavanine-containing proteins occurred rapidly but at nearly an identical rate regardless of the period of canavanine-treatment. Exposure of E. coli to heat also raised the level of protease La but showed little effect on overall rate of proteolysis. These results suggest that induction of protease La under stress occurs as a part of heat shock response but not necessarily for elimination of denatured or abnormal proteins.

Effect of garlic on thrombocyte aggregation, microcirculation, and other risk factors

Significant positive effects could be achieved in a placebo-controlled double-blind study through the administration of 800 mg of garlic powder over a period of four weeks. Spontaneous thrombocyte aggregation disappeared, the microcirculation of the skin increased by 47.6% (from 0.63 +/- 0.13 to 0.93 +/- 0.22 mm/s), plasma viscosity decreased by 3.2% (from 1.25 +/- 0.34 to 1.21 +/- 0.43 mPas), diastolic blood pressure by 9.5% (from 74 +/- 9 to 67 +/- 5 mmHg), and blood glucose concentration by 11.6% (from 89.4 +/- 8.8 to 79.0 +/- 11.9 mg/dl). The vascular protection of garlic as atherosclerosis prevention by influencing the mentioned risk parameters for cardiovascular diseases must be pointed out. Especially interesting is the thrombocyte aggregation inhibiting effect. Thus, the application of garlic may be useful in case of acetylsalicyclic acid intolerance.