Nanometre-scale thermometry in a living cell.

Sensitive probing of temperature variations on nanometre scales is an outstanding challenge in many areas of modern science and technology. In particular, a thermometer capable of subdegree temperature resolution over a large range of temperatures as well as integration within a living system could provide a powerful new tool in many areas of biological, physical and chemical research. Possibilities range from the temperature-induced control of gene expression and tumour metabolism to the cell-selective treatment of disease and the study of heat dissipation in integrated circuits. By combining local light-induced heat sources with sensitive nanoscale thermometry, it may also be possible to engineer biological processes at the subcellular level. Here we demonstrate a new approach to nanoscale thermometry that uses coherent manipulation of the electronic spin associated with nitrogen-vacancy colour centres in diamond. Our technique makes it possible to detect temperature variations as small as 1.8 mK (a sensitivity of 9 mK Hz(-1/2)) in an ultrapure bulk diamond sample. Using nitrogen-vacancy centres in diamond nanocrystals (nanodiamonds), we directly measure the local thermal environment on length scales as short as 200 nanometres. Finally, by introducing both nanodiamonds and gold nanoparticles into a single human embryonic fibroblast, we demonstrate temperature-gradient control and mapping at the subcellular level, enabling unique potential applications in life sciences.

Critical Thermalization of a Disordered Dipolar Spin System in Diamond.

Statistical mechanics underlies our understanding of macroscopic quantum systems. It is based on the assumption that out-of-equilibrium systems rapidly approach their equilibrium states, forgetting any information about their microscopic initial conditions. This fundamental paradigm is challenged by disordered systems, in which a slowdown or even absence of thermalization is expected. We report the observation of critical thermalization in a three dimensional ensemble of ∼10^{6} electronic spins coupled via dipolar interactions. By controlling the spin states of nitrogen vacancy color centers in diamond, we observe slow, subexponential relaxation dynamics and identify a regime of power-law decay with disorder-dependent exponents; this behavior is modified at late times owing to many-body interactions. These observations are quantitatively explained by a resonance counting theory that incorporates the effects of both disorder and interactions.

The abdominal aortic fenestration procedure in acute thoraco-abdominal aortic dissection with aortic branch artery ischemia.

OBJECTIVE: Diagnostic work-up and treatment strategies have improved the prognosis of acute thoraco-abdominal aortic dissection. Little attention to aortic branch artery ischemia or even failed restoration following prosthetic repair of thoraco-abdominal dissection still merit a problem with high morbidity and mortality. SETTING: Department of Vascular Surgery, Technische Universität München, Germany. PURPOSE: Reflecting on visceral and neurological ischemic complications in acute thoraco-abdominal aortic dissection indications and limitations of the abdominal-aortic-fenestration procedure are discussed with a review on our own clinical experience and the results reported in the literature. CONCLUSIONS: The abdominal-aortic-fenestration procedure is accomplished with minimal deterioration of the critically ill patient. In new onset or relief of aortic branch ischemia, following initial prosthetic repair of either type A or B dissection aortic fenestration is found to be an effective and secure adjunctive procedure to restore the blood flow of compromised organs. Primary abdominal aortic fenestration is recommended instead of prosthetic repair in cases of acute type B dissection. It is the treatment of choice because of branch artery ischemia becoming the focal point of deterioration.

Extended femoro-distal bypasses for limb salvage: are they worthwhile?

UNLABELLED: In this report on 93 patients with limb-threatening leg ischemia the surgical procedures applied were malleolar bypasses (14), sequential bypasses (12) and femoro-distal bypasses with adjunct AV fistulas (67). The first two methods resulted in favourable limb-salvage and patency rates. However the results of such reconstructions essentially depend on the quality of primary and secondary foot arcades. In peripheral calf and foot arterial occlusions we have applied a distal arteriovenous fistula as an adjunct measure to maintain bypass patency in the crural region. 67 patients were operated on according to this method: 30 females and 37 males with an average age of 70.3 years. 29% had rest-pain and 71% had gangrene. The majority had already been operated on at least once. 7 patients had been amputated contralaterally. RESULTS: 79% of the patients had a patent graft after one month. The incidence of limb salvage was 77%. At two years 47% of all grafts are still patent and the incidence of limb-salvage is 52%. However, this operation should be exclusively designed for limb-salvage and for cases with extremely poor run-off.

Migration behavior of human smooth muscle cells cultivated from restenotic and primary lesions.

Subintimal smooth muscle cell (SMC) migration is considered an essential determinant of arteriosclerosis and neointimal formation. In this study, a cell culture model was established to characterize migration activity of SMCs originating from restenotic and primary lesions. Plaques from symptomatic stenoses of 32 patients (19 men, 13 women; 4 carotid, 17 peripheral, 11 coronary lesions) were removed by percutaneous atherectomy or direct operative approach. Ten patients suffered from recurrent stenosis. Cell cultures were established by explantation of tissue samples. By indirect immunofluorescence microscopy, SMCs were shown to be the predominant cell type of all advanced lesions irrespective of their origin. The spontaneous cellular motility of SMCs was analyzed in vitro by means of a computer-assisted observation system. Cells of all groups exhibited random motility. SMC migratory velocity was found to be significantly (P < 0.001) greater in cells from restenotic lesions than in those from primary plaques. In conclusion, migration behavior of human SMCs originating from arteriosclerotic lesions may be quantified in vitro as a functional determinant characterizing restenotic versus primary lesions.

Urgent carotid endarterectomy for stroke in evolution.

BACKGROUND: Carotid endarterectomy (CEA) is well established as the elective treatment for moderate or severe carotid stenoses with a history of neurologic symptoms. In contrast, the merits of carotid revascularisation performed in emergency in patients with acute stroke or fluctuating neurological deficit remain controversial. PATIENTS AND METHODS: A total of 445 CEAs were performed on 424 patients for 212 (48%) asymptomatic and 233 (52%) symptomatic carotid stenoses within a 5 years period between January, 1995, and December, 1999. Of the latter, CEA was performed in emergency on 16 patients (3.8%) within 4 to 24 hours after the onset of symptoms. Patients selected for urgent surgery fulfilled the following criteria: acute onset of fluctuating hemispheric neurological symptoms, significant carotid pathology, absence of cerebral hemorrhage, uncompromised vigilance and stable cardiopulmonary conditions. Selected patients presented with a crescendo-TIA (n = 7) or fluctuating neurological deficits (n = 9) corresponding to a contralateral carotid stenosis. RESULTS: Following CEA, the neurological deficits improved instantaneously to complete recovery in 9 patients. The symptoms of 4 patients improved to non-disabling deficits, remained unchanged in one and worsened in 2 patients from hemihypaesthesia to hemiparesis. 14/16 patients were discharged within 8 days after admission. The neurologic status after discharge did not deteriorate in any of the patients during follow up of 19.3 +/- 13 months, but improved in 4 of the patients. CONCLUSION: Our retrospective study suggests that rescue CEA may be beneficial for selected patients with stroke in evolution and fluctuating neurological deficits. Careful adherence to selection criteria, intraoperative shunting, intensive care post surgery surveillance and an experienced team are recommended.

[High-degree bilateral carotid stenoses]. / Hochgradige bilaterale Karotis-Stenosen.

The indication for carotid endarterectomy in patients with unilateral stenotic lesions as well as the operative risk in patients with bilateral disease is still controversial among experts. We performed a retrospective analysis in our patients with bilateral carotid endarterectomy. 578 patients underwent carotid endarterectomy at our institution from 1986-1992: 54 patients (9.3%) had bilateral carotid disease. 30% of these patients were asymptomatic and 16% had symptoms from both sides. Surgical results concerning the optimal restoration of blood supply (75%) and the occurrence of recurrent stenosis (8%) were comparable for patients with unilateral and bilateral carotid endarterectomy. On the contrary, in patients with bilateral carotid disease, both the operative morbidity (2.8%) and mortality (1.8%) were increased as compared to the total study population (1.9% and 0.45% resp.). Carotid endarterectomy is very effective in preventing stroke especially in patients with multiple vessel disease as compared to the natural history of these lesions.

[Results of vascular surgery treatment of vertebrobasilar insufficiency]. / Ergebnisse gefässchirurgischer Therapie bei vertebrobasilärer Insuffizienz.

A retrospective analysis of the data of 64 patients with vertebral-basilar insufficiency is presented who were operated between 1980 to 1919 in our institution. Surgery for vertebral-basilar insufficiency comprises only 5.2% of all 1422 supra-aortic reconstructions performed during this period. The leading symptom was vertigo which was present in 41%. Disturbances of vision occurred in 9.8%. 29 bypass procedures and 35 arterial transpositions were performed. A mean follow up of 5.1 years revealed a patency rate of 83.3% in bypass procedures, 92.8% in subclavian transpositions and 100% in vertebral artery transpositions. These good haemodynamic results correlated with marked improvement of the clinical symptoms in 80% of the patients.

[Orthotopic arteriovenous fistula in dialysis patients: a special application of fluid dynamic processes]. / Die orthotopen arteriovenösen Fisteln beim Dialysepatienten: eine Sonderstellung fluiddynamischer Problematik.

Our experiments describe the flow patterns in translucent models of AV fistulas. The elasticity of the models is similar to human vessels walls. Dying of particular flow threads with methylene blue visualizes the flow and its disturbances in 4 classical models. The flow dynamics were investigated with parallel inflow. The volume flow was constant at 200 and 400 ml/min, with a volume flow ratio of 80:20. The flow pattern in side to side fistulas and in end to side fistulas with a narrow angle show regions of separation. This may lead to microthrombus formation and early failure. High shear stress causes endothelial lesions and thus induces stenosing intimal reactions. A favourable flow pattern was seen in end to side fistulas with a broad angle, as well as in end to end fistulas.

[Ablation of venous valves with Nd-Yag laser--an alternative to conventional valvulotomy?]. / Venenklappenablatio mit Nd-Yag Laser--eine Alternative zur konventionellen Valvulotomie?

The careful removal of venous valves during in situ venous bypass procedures is a problem that has not been completely solved. In this experimental study, valve ablation with the Nd-Yag laser was compared with conventional valvulotomy. The investigation was performed in vitro using human vein segments with a length of 20 cm. Conventional valvulotomy was performed 16 times, 20 valves were removed with a 400 mu-fibre and 26 with the hot tip. The results were evaluated by endoscopy, light and electron microscopy. There were no vein perforations with the valvulotome and the hot tip. Endothelial damage was documented in 85% with the valvulotome and was reduced significantly to 58% with the 400 mu-fibre. With the hot tip endothelial lesions were seen in only 30%. Valve remnants were always present with the valvulotome and in no more than 15% with the hot tip. Electron microscopy supported these results in general. There was no endothelial damage in 69%.

Severe bilateral carotid stenosis.

An analysis of the relevant data from the Veterans Affairs Cooperative Study Group in asymptomatic patients, showed that 26 of the 32 ipsilateral strokes occurred during the first two years of clinical follow-up. Furthermore, as observed in the medical group, half the neurologic outcome events were strokes and were not preceded by transient ischemic attacks. In the North American Symptomatic Carotid Endarterectomy Trial over a 2-year period, 45 percent of those with occlusion had a stroke compared to 15 percent in the surgical group. These data dispel the traditionally held view that patients with severe contralateral disease should not be subjected to surgery. However, the referral of patients to centers capable of low rates of surgical complications is essential in a plan that includes carotid endarterectomy with optimal medical management.

[Surgical aortic fenestration in acute thoracoabdominal aortic dissection with abdominal malperfusion and end organ ischemia]. / Die Aortenfensterungsoperation bei akuter thoracoabdominaler Aortendissektion mit abdominaler Malperfusion und Endorganischämie.

Intestinal, renal, spinal or peripheral arterial ischemia or failure of branch artery recanalization following initial prosthetic repair of thoracoabdominal aortic dissection is still a problem, with high morbidity and mortality. Five consecutive patients with acute thoracoabdominal aortic dissection (two type A dissections, three type B dissections) suffering from concomitant intestinal, renal, spinal and acute peripheral arterial ischemia are reported. Considering the anatomical and pathophysiological basis of thoracoabdominal aortic dissection and concomitant organ ischemia, the aortic fenestration procedure as a primary or secondary operative approach succeeded in restoring blood flow in all cases without complications. Assessment of the long-term results after 3 years revealed that all patients are doing well without any residual complaints. We conclude that in the case of persistent or secondary onset of aortic branch artery ischemia following initial prosthetic repair of either type A or type B dissection, aortic fenestration can be recommended immediately as a staged operative approach. Primary abdominal aortic fenestration is justified in acute type B dissection when end-organ ischemia becomes the focus of clinical deterioration.

Scalable architecture for a room temperature solid-state quantum information processor.

The realization of a scalable quantum information processor has emerged over the past decade as one of the central challenges at the interface of fundamental science and engineering. Here we propose and analyse an architecture for a scalable, solid-state quantum information processor capable of operating at room temperature. Our approach is based on recent experimental advances involving nitrogen-vacancy colour centres in diamond. In particular, we demonstrate that the multiple challenges associated with operation at ambient temperature, individual addressing at the nanoscale, strong qubit coupling, robustness against disorder and low decoherence rates can be simultaneously achieved under realistic, experimentally relevant conditions. The architecture uses a novel approach to quantum information transfer and includes a hierarchy of control at successive length scales. Moreover, it alleviates the stringent constraints currently limiting the realization of scalable quantum processors and will provide fundamental insights into the physics of non-equilibrium many-body quantum systems.

Room-temperature quantum bit memory exceeding one second.

Stable quantum bits, capable both of storing quantum information for macroscopic time scales and of integration inside small portable devices, are an essential building block for an array of potential applications. We demonstrate high-fidelity control of a solid-state qubit, which preserves its polarization for several minutes and features coherence lifetimes exceeding 1 second at room temperature. The qubit consists of a single (13)C nuclear spin in the vicinity of a nitrogen-vacancy color center within an isotopically purified diamond crystal. The long qubit memory time was achieved via a technique involving dissipative decoupling of the single nuclear spin from its local environment. The versatility, robustness, and potential scalability of this system may allow for new applications in quantum information science.

[Vascular injuries during skiing]. / Gefässverletzungen beim Skisport

Traumatic lesions of blood vessels occur only rarely in skiing, they are, however, mostly very dramatic events which may lead to the loss of an extremity. Relatively simple measures of diagnosis and therapy may save the skier's threatened life and extremity. Some of these are: Realization that a vascular trauma has occurred, tight pressure bandage, bringing the patient into shock-position, immediate transport by helicopter to a medical center with surgeons trained in vascular surgery.

[Diagnosis and first dressings of vascular injuries in emergency calls (author's transl)]. / Diagnostik und Erstversorgung von Gefäss - verletzungen im Notarzteinsatz

With vascular injuries, both the first measures at the site of the accident and also rapid transport (helicopter) to a central specialized hospital with possibilities for vascular surgical care are of decisive importance for the maintenance of life and limb of the patient. From our experience in 169 patients with vascular injuries which were treated between 1967 and 1975, observation of the diagnostic and therapeutic measures described is of the greatest importance for the prognosis of vascular trauma.

[The fatal ski accident]. / Der tödliche Skiunfall

This investigation analyzes 18 fatal skiing accidents which happened from 1959 to 1975. Deadly accidents caused by avalanches were not taken into consideration. The results of the authors were compared with reports of altogether sixty similar injuries due to skiing accidents. 46% of the fatal accidents were caused by crashing against hindrances. Half of the accidents happened during high-speed-skiing or downhill-competition. More than two-thirds of the wounded skiers died of head injuries. Therefore it is highly recommended to wear a suitable headprotection while skiing downhill.