Design Study of a Novel Positron Emission Tomography System for Plant Imaging

Positron Emission Tomography is a non-disruptive and high-sensitive digital imaging technique which allows to measure in-vivo and non invasively the changes of metabolic and transport mechanisms in plants. When it comes to the early assessment of stress-induced alterations of plant functions, plant PET has the potential of a major breakthrough. The development of dedicated plant PET systems faces a series of technological and experimental difficulties, which make conventional clinical and preclinical PET systems not fully suitable to agronomy. First, the functional and metabolic mechanisms of plants depend on environmental conditions, which can be controlled during the experiment if the scanner is transported into the growing chamber. Second, plants need to be imaged vertically, thus requiring a proper Field Of View. Third, the transverse Field of View needs to adapt to the different plant shapes, according to the species and the experimental protocols. In this paper, we perform a simulation study, proposing a novel design of dedicated plant PET scanners specifically conceived to address these agronomic issues. We estimate their expected sensitivity, count rate performance and spatial resolution, and we identify these specific features, which need to be investigated when realizing a plant PET scanner. Finally, we propose a novel approach to the measurement and verification of the performance of plant PET systems, including the design of dedicated plant phantoms, in order to provide a standard evaluation procedure for this emerging digital imaging agronomic technology.

Akupunktur - quo vadis?

On the current discussion about efficacy and "point-specificity" of the needle therapy To improve the evidence base for acupuncture in pain treatment the German health insurance initiated the so called "Acupuncture randomised trials (ART)" and "German Acupuncture Trials" (GERAC) with a sample size of 300 (ART) and 1000 (GERAC) patients, providing a new dimension in acupuncture research. These studies have yielded data, which indicate that acupuncture is effective in the treatment of migraine, tension type headache, osteoarthritis of the knee and chronic low back pain. For the two latter indications acupuncture showed an even higher therapeutic response rate than conventional standard treatment. In migraine acupuncture showed an effect comparable to pharmacological treatment. The studies moreover indicate that the relevance of point-specific effects may have been overestimated concerning some indications. This article discusses the results of ART and GERAC, based on differentiating the mechanisms of action in acupuncture therapy. It is shown that the current data neither support the postulate of a "no-matter-where acupuncture" nor the irrefutability of the theorems of Chinese Medicine. Future studies will have to determine more precisely the mechanism by which the therapeutic effect of acupuncture is mediated. Furthermore, it will be necessary to find out more clearly in what diseases the location of needling represents the crucial part of the treatment and in what diseases rather different factors, like the intensity of stimulation or the doctor-patient interaction, are more relevant for the therapeutic effect. Research into acupuncture is still at the beginning. For this reason it should be avoided to draw premature and untenable conclusions from the current data.

Incorporation of Fasting Therapy in an Integrative Medicine Ward: Evaluation of Outcome, Safety, and Effects on Lifestyle Adherence in a Large Prospective Cohort Study

OBJECTIVES

The aim of this study was to implement fasting therapy in an inpatient integrative medicine ward and to evaluate safety, acceptance, and effects on health-related outcomes and lifestyle adherence.

DESIGN

This was a prospective observational study with consecutive inpatients over 3 [corrected] years. Inclusion and exclusion criteria for fasting therapy were checked by treating physicians and recommendations given. After receiving full information patients decided whether they would participate in fasting. Outcomes were assessed on admission, at discharge, and 3 and 6 months after discharge.

SETTING

The study took place in an integrative medicine department of an academic teaching hospital.

SUBJECTS

Subjects were newly admitted inpatients with chronic internal diseases and chronic pain syndromes, with lengths of hospital stay of >3 days.

INTERVENTIONS

All patients received intensive integrative treatments including Mind/Body Medicine, acupuncture, nutritional/lifestyle education, and hydrotherapy. Fasting patients participated in a 7-day juice fast (intake <350 kcal/day) with accompanying bowel cleansing, 2 prefasting relief days, and 3 days with stepwise reintroduction of food.

OUTCOME MEASURES

Outcomes were assessed based on rate of participation in fasting, severity of main complaint, quality of life (QOL, MOS 36-Item Short-Form Health Survey), safety, lifestyle adherence to recommendations given (relaxation, diet, exercise).

RESULTS

Of 2121 patients with complete discharge questionnaires, 952 patients participated in fasting, 873 had a normocaloric vegetarian diet, and 296 patients had other diets and were excluded. Response rates were 71% and 56% at 3- and 6-month follow-up. The main disease-related complaint at discharge was significantly greater improved in fasters versus nonfasters (p < 0.01). Patient QOL increased significantly and comparably from baseline to discharge in both groups. Fasting was well tolerated and no serious fasting-related adverse effects were reported. In all, 743 (78%) of fasting patients reported improvement of their health through fasting. Descriptors of lifestyle adherence showed higher levels of related activities in the 3 and 6 months of follow-up.

CONCLUSIONS

Fasting can safely and successfully be implemented in an inpatient integrative medicine concept and is perceived as a health-promoting method by the majority of patients. Potential effects on disease-related complaints and lifestyle adherence should be further evaluated in randomized trials.

[Acupuncture in the treatment of pain--hypothesis to adaptive effects]

A basic principle in conventional pain therapy is that the treatment should be tailored to the pathological mechanism of the disease. This is based on the knowledge of the effector mechanisms of the applied treatment modalities. Although for acupuncture the mode of action still remains elusive in many parts, evidence about its mechanisms in pain treatment is growing. A better understanding of the hypalgesic effects of acupuncture might lead to a more differentiated and mechanism guided application. The aim of this article is to evaluate the scientific data about the neurobiological mechanisms of acupuncture in the treatment of pain. Data are critically evaluated regarding their relevance for clinical practice. Possible mechanisms are differentiated in local and systemic effects and the question of point specificity is discussed. Additionally a comprehensive hypothesis is set up for the long-term effects of acupuncture in the treatment of chronic pain. In this context acupuncture is considered as a mode of repetitive, nociceptive stimulation, which induces adaptive processes on different physiological levels leading to an improved ability of the nociceptive system to cope with painful stimuli.

Changes of Cerebrovascular Response to Visual Stimulation in Migraineurs After Repetitive Sessions of Somatosensory Stimulation (Acupuncture): A Pilot Study

OBJECTIVES

To evaluate the effect of repetitive somatosensory stimulation (acupuncture) on cerebrovascular response in migraineurs by functional transcranial Doppler.

METHODS

Changes of cerebral blood flow velocity in the right posterior and left middle cerebral arteries were measured by functional transcranial Doppler during visual stimulation (flickering light over 57 seconds) in 10 migraineurs before and after 10 acupuncture sessions. The same stimulation paradigm was performed in 10 control subjects. Cerebral blood flow velocity data were analyzed with a previously validated technique based on automated stimulus-related averaging. To evaluate the clinical effect of the treatment, a headache diary monitored the frequency and intensity of the migraine attacks. A positive treatment effect was defined as a reduction of at least 50% in the attack frequency or the mean headache intensity (or both).

RESULTS

Before treatment, migraineurs showed overshooting cerebral blood flow velocity changes at the beginning and at the end of the stimulation and a delayed decline to baseline compared with control subjects. After treatment, this response pattern was significantly diminished (P</=.05) in those who benefited from treatment (n = 6). Those who did not benefit from treatment (n = 4) showed a significantly (P</=.05) more marked alteration of the cerebral blood flow velocity pattern.

CONCLUSIONS

Data indicate that repetitive somatosensory stimulation (acupuncture) might positively influence the abnormal cerebrovascular response in migraineurs. In a subgroup of migraineurs, however, the dysfunction of the cerebrovascular system might deteriorate under the treatment.

Different modes of manual acupuncture stimulation differentially modulate cerebral blood flow velocity, arterial blood pressure and heart rate in human subjects

The psychophysiological effect of different modes of manual acupuncture stimulation was investigated in 12 healthy, right handed, male subjects (mean age 29). The cerebral blood flow velocity (CBFV) in both middle cerebral arteries, arterial blood pressure (BP), heart rate (HR) and the perceived intensity of the stimulation were monitored while an acupuncture needle in the right dorsal thenar muscle (point Hegu, Li 4) was repetitively rotated with either high frequency (4-8 Hz) and low amplitude (hf-la) or low frequency (1-2 Hz) and high amplitude (lf-ha). Response patterns induced by hf-la and 1f-ha [corrected] stimulation differed significantly (P < 0.05) as tested by Student's t-test: (1), 1f-ha [corrected] stimulation was perceived as more intense and induced a more marked right hemispheric CBFV increase; (2), while hf-la stimulation lead to a slight decrease of BP and HR, lf-ha stimulation induced an initial pressor response (increase of BP, decrease of HR) and a more marked long term decrease of BP. Data indicate that the mode of manual acupuncture stimulation has a differential effect on the perceived stimulation intensity, the cerebral activation and the cardiovascular reflex response.

[Investigations on the effect of acupuncture on affective and sensory components of pain in patients with different stages of chronic pain]

OBJECTIVES

The aim of the study was to investigate the effects of acupuncture on the affective and sensory experience of pain in chronic pain patients. Furthermore, the study tried to estimate the therapeutical benefit of acupuncture in relation to the stage of chronic pain according to the Mainz pain staging system for chronic pain (MPSS).

METHODS

Patients with chronic pain syndromes who received acupuncture treatment answered a standardized pain questionnaire before and after treatment. The questionnaire included the visual-analogue-scale for the intensity of pain, the pain perception scale for the assessment of affective and sensory components of pain perception, and addressed the patients to the three stages of chronic pain (MPSS).

RESULTS

From April 1997 to October 1999, patients (n = 165) suffering from chronic headache and facial pain syndromes (23%), spine associated pain syndromes (48%) or other pain conditions (29%) were subsequently included. Treatment with acupuncture showed a more pronounced reduction of the affective assessment than of the sensory assessment of pain. These effects were particularly pronounced in patients assigned to stage 3 of chronic pain (MPSS).

CONCLUSIONS

Acupuncture in patients with high-stage chronic pain syndromes preferentially influences the affective dimension of pain perception. For the estimation of the overall clinical outcome of acupuncture treatment, a differentiation between affective and sensory components of pain is recommended.

Altered cerebrovascular response pattern in interictal migraine during visual stimulation

A dysbalance of the cerebrovascular response during functional activation of the brain has been postulated as a factor in the pathophysiology of migraine. To determine the dynamic pattern of the cerebrovascular response in migraineurs compared with a control group, changes of the cerebral perfusion during cerebral activation were studied with high temporal resolution by functional transcranial Doppler sonography (fTCD). The cerebral blood flow velocity (CBFV) in the right posterior cerebral artery (PCA) and the left middle cerebral artery (MCA) was measured simultaneously during visual stimulation in 19 interictal migraineurs and in 19 age- and sex-matched control subjects. Data were analysed with a previously validated technique based on automated stimulus-related averaging of the CBFV. The MCA migraineurs exhibited a steady increase of CBFV during the stimulation, while normal subjects showed a habituation of the CBFV response. The lack of habituation in migraineurs was significantly (P < or = 0.05) more pronounced across patients with a high attack frequency (> or = 4 per month) compared with migraineurs with a low attack frequency (< 4 per month). In the PCA, compared with normal subjects, migraineurs showed significantly (P < or = 0.05) stronger CBFV changes at the beginning and after the end of stimulation, with a slower decline to baseline. Data are in accordance with electrophysiological findings in migraineurs. It is assumed that a lack of habituation of the cerebrovascular response in migraineurs might contribute to a disturbance of the metabolic homeostasis of the brain that might induce migraine attacks.

Cortical tuning: a function of anticipated stimulus intensity

We investigated the activation of the brain during anticipation of tactile stimuli by continuous cerebral blood flow velocity (CBFV) monitoring with bilateral transcranial Doppler sonography. A forced choice paradigm was performed where a first group of subjects (n=16) was expecting suprathreshold and a second group (n=19) was anticipating threshold tactile stimuli to the index finger after a cueing tone. During the anticipation of suprathreshold stimuli the CBFV always exhibited a significantly stronger increase in the right hemisphere than in the left, even when stimuli were anticipated at the right index finger. Conversely when stimuli at perception threshold were expected, the respective contralateral hemisphere showed a significantly stronger perfusion increase. These data show that preparatory activation of the brain during stimulus anticipation is dependant on the expected stimulus intensity.

Regional cerebral blood flow increases during preparation for and processing of sensory stimuli

Preparing for and processing of sensory stimuli are energy-requiring processes. We attempted to assess the relative contributions of these processes to increases in regional cerebral perfusion. Nineteen healthy right-handed subjects were examined while they were engaged in detecting tactile stimuli to the index finger 5 s after a cueing tone. Cerebral blood flow velocity (CBFV) modulations in the middle cerebral arteries (MCAs) were continuously measured by bilateral simultaneous transcranial Doppler ultrasonography. Tactile stimuli well above threshold per se did not produce a significant, relative CBFV increase in the contralateral MCA. However, when subjects were expecting a threshold tactile stimulus, there was a significant regional increase in CBFV in the hemisphere contralateral to the attended index finger for approximately 15 s, starting within the first seconds after the cueing. This increase was present even before the tactile stimulus was applied and also in sessions when the stimulus was omitted. We conclude that preparation of the cortex causes a stronger regional cerebral blood flow increase than the processing of the tactile stimulus itself.

Reappraisal of indications and limitations of oxime therapy in organophosphate poisoning

1 In vitro studies with human erythrocyte acetylcholinesterase (AChE) and the mouse diaphragm model were performed to unravel the various microscopic reaction parameters that contribute to the dynamic equilibrium of AChE inhibition, ageing and reactivation. These data may help to define more precisely the indications and limitations of oxime therapy in organophosphate (OP) poisoning. 2 Diethylphosphoryl-AChE resulting from intoxications with parathion, chlorpyrifos, chlorfenvinphos, diazinon and other OPs is characterized by slow spontaneous reactivation and low propensity for ageing. This kind of phosphorylated enzyme is particularly susceptible to reactivation by oximes. 3 None of the oximes tested (pralidoxime, obidoxime, HI 6 and HLö 7) can be regarded as a universally suitable reactivator. Obidoxime turned out to be the most potent and most efficacious oxime in reactivating AChE inhibited by various classes of OP insecticides and tabun. Obidoxime, however, was inferior to HI 6 against soman, sarin, cyclosarin and VX. Pralidoxime was generally less potent. 4 The kinetic data of reactivation established for diethylphosphoryl-AChE of human red cells indicate that the usually recommended dosage to attain a plasma concentration of 4 micrograms/ml does not permit exploitation of the full therapeutic potential of the oximes, in particular of pralidoxime. However, in suicidal mega-dose poisoning, oximes, even at optimal plasma concentrations, may be unable to cope with the fast re-inhibition of reactivated AChE in the first days following intoxication. 5 It is suggested that oximes be administered by continuous infusion following an initial bolus dose as long as reactivation can be expected and until permanent clinical improvement is achieved.

Reactivation by various oximes of human erythrocyte acetylcholinesterase inhibited by different organophosphorus compounds

The new bispyridinium oximes HI 6 and HLö 7 are promising antidotes against poisoning by highly toxic organophosphorus compounds, i.e. nerve agents. Until now, their ability to reactivate pesticide inhibited human acetylcholinesterase (AChE) has not been elucidated. For this purpose human erythrocyte AChE (EC 3.1.1.7) was inhibited (30 min) by chlorfenvinphos, dichlorvos, dicrotophos, heptenophos, mevinphos, monocrotophos, paraoxon, phosphamidon, trichlorfon, malaoxon, omethoate, oxydemeton-methyl or methamidophos by 85-98% of control. After removal of excess inhibitor, obidoxime, pralidoxime (2-PAM), HI 6 or HLö 7 (10, 30 or 100 mumol/l) were added and the AChE activity was measured spectrophotometrically at various times thereafter (5-60 min). The oximes significantly, but not completely, reactivated organophosphate inhibited AChE. The velocity and extent of reactivation were dependent on the oxime and its concentration. In all cases obidoxime was superior to the three other oximes, followed by HLö 7, 2-PAM and HI 6. In most cases obidoxime and HLö 7 were most effective at 10 or 30 mumol/l while 2-PAM and HI 6 needed 100 mumol/l. These data suggest that 2-PAM HI 6 and HLö 7 are less patent than obidoxime in reactivating human AChE inhibited by organophosphate pesticides.