The 2018 hot drought pushed conifer wood formation to the limit of its plasticity: Consequences for woody biomass production and tree ring structure

Hot droughts are expected to increase in Europe and disturb forest ecosystem functioning. Wood formation of trees has the potential to adapt to those events by compensatory mechanisms between the rates and durations of tracheid differentiation to form the typical pattern of vital wood anatomical structures. We monitored xylogenesis and measured wood anatomy of mature silver fir (Abies alba Mill.) and Scots pine (Pinus sylvestris L.) trees along an elevational gradient in the Black Forest during the hot drought year of 2018. We assessed the kinetics of tracheid differentiation and the final tracheid dimensions and quantified the relationship between rates and durations of cell differentiation over the growing season. Cell differentiation kinetics were decoupled, and temperature and water availability signals were imprinted in the tree ring structure. The sudden decline in woody biomass production provided evidence for a disruption in carbon sequestration processes due to heat and drought stress. Growth processes of Scots pine (pioneer species) were mainly affected by the spring drought, whereas silver fir (climax species) growth processes were more disturbed by the summer drought. Our study provides novel insights on the plasticity of wood formation and carbon allocation in temperate conifer tree species in response to extreme climatic events.

Central European 2018 hot drought shifts scots pine forest to its tipping point

The occurrence of hot drought, i.e. low water availability and simultaneous high air temperature, represents a severe threat to ecosystems. Here, we investigated how the 2018 hot drought in Central Europe caused a tipping point in tree and ecosystem functioning in a Scots pine (Pinus sylvestris L.) forest in southwest Germany. Measurements of stress indicators, such as needle water potential, carbon assimilation and volatile organic compound (VOC) emissions, of dominant P. sylvestris trees were deployed to evaluate tree functioning during hot drought. Ecosystem impact and recovery were assessed as ecosystem carbon exchange, normalized difference vegetation index (NDVI) from satellite data and tree mortality data. During summer 2018, needle water potentials of trees dropped to minimum values of -7.5 ± 0.2 MPa, which implied severe hydraulic impairment of P. sylvestris. Likewise, carbon assimilation and VOC emissions strongly declined after mid-July. Decreasing NDVI values from August 2018 onwards were detected, along with severe defoliation in P. sylvestris, impairing ecosystem carbon flux recovery in 2019, shifting the forest into a year-round carbon source. A total of 47% of all monitored trees (n = 368) died by September 2020. NDVI recovered to pre-2018 levels in 2019, likely caused by emerging broadleaved understorey species. The 2018 hot drought had severe negative impacts on P. sylvestris. The co-occurrence of unfavourable site-specific conditions with recurrent severe droughts resulted in accelerated mortality. Thus, the 2018 hot drought pushed the P. sylvestris stand towards its tipping point, with a subsequent vegetation shift to a broadleaf-dominated forest.

Colloid volume loading does not mitigate decreases in central blood volume during simulated haemorrhage while heat stressed

Heat stress results in profound reductions in the capacity to withstand a simulated haemorrhagic challenge; however, this capacity is normalized if the individual is volume loaded prior to the challenge. The present study tested the hypothesis that volume loading during passive heat stress attenuates the reduction in regional blood volumes during a simulated haemorrhagic challenge imposed via lower-body negative pressure (LBNP). Seven subjects underwent 30 mmHg LBNP while normothermic, during passive heat stress (increased internal temperature ∼1◦C), and while continuing to be heated after intravenous colloid volume loading (11 ml kg⁻¹). Relative changes in torso and regional blood volumes were determined by gamma camera imaging with technetium-99m labelled erythrocytes. Heat stress reduced blood volume in all regions (ranging from 7 to 16%), while subsequent volume loading returned those values to normothermic levels. While normothermic,LBNP reduced blood volume in all regions (torso: 22 ± 8%; heart: 18 ± 6%; spleen: 15 ± 8%). During LBNP while heat stressed, the reductions in blood volume in each region were markedly greater when compared to LBNP while normothermic (torso: 73 ± 2%; heart: 72 ± 3%; spleen: 72 ± 5%, all P<0.001 relative to normothermia). Volume loading during heat stress did not alter the extent of the reduction in these blood volumes to LBNP relative to heat stress alone (torso: 73 ± 1%; heart: 72 ± 2%; spleen: 74 ± 3%, all P>0.05 relative to heat stress alone). These data suggest that blood volume loading during passive heat stress (via 11 ml kg⁻¹ of a colloid solution) normalizes regional blood volumes in the torso, but does not mitigate the reduction in central blood volume during a simulated haemorrhagic challenge combined with heat stress.

Plasma pH does not influence the cerebral metabolic ratio during maximal whole body exercise

Exercise lowers the cerebral metabolic ratio of O2 to carbohydrate (glucose+1/2 lactate) and metabolic acidosis appears to promote cerebral lactate uptake. However, the influence of pH on cerebral lactate uptake and, in turn, on the cerebral metabolic ratio during exercise is not known. Sodium bicarbonate (Bicarb, 1 M; 350-500 ml) or an equal volume of normal saline (Sal) was infused intravenously at a constant rate during a '2000 m' maximal ergometer row in six male oarsmen (23±2 years; mean±S.D.). During the Sal trial, pH decreased from 7.41±0.01 at rest to 7.02±0.02 but only to 7.36±0.02 (P <0.05) during the Bicarb trial. Arterial lactate increased to 21.4±0.8 and 32.7±2.3 mM during the Sal and Bicarb trials, respectively (P <0.05). Also, the arterial-jugular venous lactate difference increased from-0.03±0.01 mM at rest to 3.2±0.9 mM (P <0.05) and 3.4±1.4 mM (P <0.05) following the Sal and Bicarb trials, respectively. Accordingly, the cerebral metabolic ratio decreased equally during the Sal and Bicarb trials: from 5.8±0.6 at rest to 1.7±0.1 and 1.8±0.2, respectively. The enlarged blood-buffering capacity after infusion of Bicarb eliminated metabolic acidosis during maximal exercise but that did not affect the cerebral lactate uptake and, therefore, the decrease in the cerebral metabolic ratio.

Effect of volume loading on the Frank-Starling relation during reductions in central blood volume in heat-stressed humans

During reductions in central blood volume while heat stressed, a greater decrease in stroke volume (SV) for a similar decrease in ventricular filling pressure, compared to normothermia, suggests that the heart is operating on a steeper portion of a Frank-Starling curve. If so, volume loading of heat-stressed individuals would shift the operating point to a flatter portion of the heat stress Frank-Starling curve thereby attenuating the reduction in SV during subsequent decreases in central blood volume. To investigate this hypothesis, right heart catheterization was performed in eight males from whom pulmonary capillary wedge pressure (PCWP), central venous pressure and SV (via thermodilution) were obtained while central blood volume was reduced via lower-body negative pressure (LBNP) during normothermia, whole-body heating (increase in blood temperature 1 degrees C), and during whole-body heating after intravascular volume expansion. Volume expansion was accomplished by administration of a combination of a synthetic colloid (HES 130/0.4, Voluven) and saline. Before LBNP, SV was not affected by heating (122 +/- 30 ml; mean +/- s.d.) compared to normothermia (110 +/- 20 ml; P = 0.06). However, subsequent volume loading increased SV to 143 +/- 29 ml (P = 0.003). LBNP provoked a larger decrease in SV relative to the decrease in PCWP during heating (8.6 +/- 1.9 ml mmHg(1)) compared to normothermia (4.5 +/- 3.0 ml mmHg(1), P = 0.02). After volume loading while heat stressed, the reduction in the SV to PCWP ratio during LBNP was comparable to that observed during normothermia (4.8 +/- 2.3 ml mmHg(1); P = 0.78). These data support the hypothesis that a Frank-Starling mechanism contributes to compromised blood pressure control during simulated haemorrhage in heat-stressed individuals, and extend those findings by showing that volume infusion corrects this deficit by shifting the operating point to a flatter portion of the heat stress Frank-Starling curve.

Changes in presumed motor cortical activity during fatiguing muscle contraction in humans

AIM

Changes in sensory information from active muscles accompany fatiguing exercise and the force-generating capacity deteriorates. The central motor commands therefore must adjust depending on the task performed. Muscle potentials evoked by transcranial magnetic stimulation (TMS) change during the course of fatiguing muscle activity, which demonstrates activity changes in cortical or spinal networks during fatiguing exercise. Here, we investigate cortical mechanisms that are actively involved in driving the contracting muscles.

METHODS

During a sustained submaximal contraction (30% of maximal voluntary contraction) of the elbow flexor muscles we applied TMS over the motor cortex. At an intensity below motor threshold, TMS reduced the ongoing muscle activity in biceps brachii. This reduction appears as a suppression at short latency of the stimulus-triggered average of rectified electromyographic (EMG) activity. The magnitude of the suppression was evaluated relative to the mean EMG activity during the 50 ms prior to the cortical stimulus.

RESULTS

During the first 2 min of the fatiguing muscle contraction the suppression was 10 +/- 0.9% of the ongoing EMG activity. At 2 min prior to task failure the suppression had reached 16 +/- 2.1%. In control experiments without fatigue we did not find a similar increase in suppression with increasing levels of ongoing EMG activity.

CONCLUSION

Using a form of TMS which reduces cortical output to motor neurones (and disfacilitates them), this study suggests that neuromuscular fatigue increases this disfacilitatory effect. This finding is consistent with an increase in the excitability of inhibitory circuits controlling corticospinal output.

Cerebral oxygenation and metabolism during exercise following three months of endurance training in healthy overweight males

Endurance training improves muscular and cardiovascular fitness, but the effect on cerebral oxygenation and metabolism remains unknown. We hypothesized that 3 mo of endurance training would reduce cerebral carbohydrate uptake with maintained cerebral oxygenation during submaximal exercise. Healthy overweight males were included in a randomized, controlled study (training: n = 10; control: n = 7). Arterial and internal jugular venous catheterization was used to determine concentration differences for oxygen, glucose, and lactate across the brain and the oxygen-carbohydrate index [molar uptake of oxygen/(glucose + (1/2) lactate); OCI], changes in mitochondrial oxygen tension (DeltaP(Mito)O(2)) and the cerebral metabolic rate of oxygen (CMRO(2)) were calculated. For all subjects, resting OCI was higher at the 3-mo follow-up (6.3 +/- 1.3 compared with 4.7 +/- 0.9 at baseline, mean +/- SD; P < 0.05) and coincided with a lower plasma epinephrine concentration (P < 0.05). Cerebral adaptations to endurance training manifested when exercising at 70% of maximal oxygen uptake (approximately 211 W). Before training, both OCI (3.9 +/- 0.9) and DeltaP(Mito)O(2) (-22 mmHg) decreased (P < 0.05), whereas CMRO(2) increased by 79 +/- 53 micromol x 100 x g(-1) min(-1) (P < 0.05). At the 3-mo follow-up, OCI (4.9 +/- 1.0) and DeltaP(Mito)O(2) (-7 +/- 13 mmHg) did not decrease significantly from rest and when compared with values before training (P < 0.05), CMRO(2) did not increase. This study demonstrates that endurance training attenuates the cerebral metabolic response to submaximal exercise, as reflected in a lower carbohydrate uptake and maintained cerebral oxygenation.

Cerebral oxygenation decreases during exercise in humans with beta-adrenergic blockade

AIM

Beta-blockers reduce exercise capacity by attenuated increase in cardiac output, but it remains unknown whether performance also relates to attenuated cerebral oxygenation.

METHODS

Acting as their own controls, eight healthy subjects performed a continuous incremental cycle test to exhaustion with or without administration of the non-selective beta-blocker propranolol. Changes in cerebral blood flow velocity were measured with transcranial Doppler ultrasound and those in cerebral oxygenation were evaluated using near-infrared spectroscopy and the calculated cerebral mitochondrial oxygen tension derived from arterial to internal jugular venous concentration differences.

RESULTS

Arterial lactate and cardiac output increased to 15.3 +/- 4.2 mM and 20.8 +/- 1.5 L min(-1) respectively (mean +/- SD). Frontal lobe oxygenation remained unaffected but the calculated cerebral mitochondrial oxygen tension decreased by 29 +/- 7 mmHg (P < 0.05). Propranolol reduced resting heart rate (58 +/- 6 vs. 69 +/- 8 beats min(-1)) and at exercise exhaustion, cardiac output (16.6 +/- 3.6 L min(-1)) and arterial lactate (9.4 +/- 3.7 mM) were attenuated with a reduction in exercise capacity from 239 +/- 42 to 209 +/- 31 W (all P < 0.05). Propranolol also attenuated the increase in cerebral blood flow velocity and frontal lobe oxygenation (P < 0.05) whereas the cerebral mitochondrial oxygen tension decreased to a similar degree as during control exercise (delta 28 +/- 10 mmHg; P < 0.05).

CONCLUSION

Propranolol attenuated the increase in cardiac output of consequence for cerebral perfusion and oxygenation. We suggest that a decrease in cerebral oxygenation limits exercise capacity.

Occurrence of Atractolytocestus huronensis (Cestoda, Caryophyllaeidae) in German pond-farmed common carp Cyprinus carpio

Up to now, the caryophyllid cestode Atractolytocestus huronensis Anthony, 1958, a parasite of common carp, has attracted little attention in Germany. Based on recent publications from the Czech Republic and Hungary, it appears probable that this cestode may be increasingly common in Germany. There is a strong connection between the occurrence of A. huronensis and imports of common carp from the Czech Republic and southern Germany. Although in most cases no clinical alterations in parasitized carp have been observed, care should be taken to avoid further dissemination and to prevent possible losses in commercial pond farming.

Lack of association of lobar intracerebral hemorrhage with apolipoprotein E genotype in an unselected population

BACKGROUND

Both the upsilon2 and upsilon4 alleles of the apolipoprotein E gene (APOE) have been reported to be overrepresented in lobar intracerebral hemorrhage and to be associated with cerebral amyloid angiopathy (CAA). These studies were performed primarily on the North American population and investigated in partly selected patient cohorts.

METHODS

193 consecutive patients suffering from primary intracerebral hemorrhage (ICH) were included in our study. The localization of the ICH, i.e. cortico-subcortical, deep white matter, basal ganglia, brainstem and cerebellum, was put in relation to the APOE genotype and vascular risk factors. In 101 of these patients, the APOE genotype was also correlated to the presence and distribution of microbleeds and other microangiopathy-related damage, as shown by magnetic resonance imaging (MRI).

RESULTS

We found neither an association of a specific APOE genotype with ICH localization nor with microangiopathy-related MRI findings.

CONCLUSIONS

In our study of an unselected Central European population, the APOE genotype was not confirmed as a candidate for providing additional diagnostic and potentially prognostic information in patients with ICH.

Acute small subcortical infarctions on diffusion weighted MRI: clinical presentation and aetiology

OBJECTIVE

To determine the clinical presentation and aetiology of small subcortical infarctions as found on diffusion weighted magnetic resonance imaging (DWI). DWI is both sensitive and specific in the early detection of acute ischaemic brain lesions irrespective of pre-existing vascular damage.

METHODS

Ninety three patients were identified showing subcortical or brainstem DWI lesions <1.5 cm in diameter within a maximum of 7 days from the onset of stroke symptoms. The patients' clinical status on admission was reviewed according to the Oxfordshire Community Stroke Project (OCSP). The results of procedures searching for cerebrovascular risk factors, large artery disease, and potential sources of cardiac embolism were included to determine stroke aetiology. Magnetic resonance imaging scans were also reviewed for concomitant changes that could support the aetiologic classification.

RESULTS

Only 41 (44.1%) patients presented clinically with a lacunar syndrome according to OCSP criteria. The nine (9.7%) patients who showed two or more DWI lesions in different vascular territories were also significantly more likely to have potential sources of cardiac embolism (5/9, 55.6% v 20/84, 23.8%). Hypertension was significantly more prevalent in the group of patients who showed a microangiopathy related imaging pattern, but this pattern did not exclude the presence of large artery disease or a possible cardioembolic source of stroke.

CONCLUSION

Identification of small subcortical infarctions as the cause of stroke appears quite uncertain based on clinical characteristics only. DWI adds significant aetiologic information but does not obviate the search for other potentially causative mechanisms.

Growth of adult Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.) under free-air ozone fumigation

This study attempted to detect the impact of ozone on adult trees of Norway spruce ( Picea abies [L.] Karst.) and European beech ( Fagus sylvatica L.) in an experimental mixed stand in Southern Bavaria, Germany. The aim was to examine whether there is a decrease in growth when trees are exposed to higher than atmospheric concentrations of ozone. This exposure was put into effect using a free-air fumigation system at tree crown level. Growth analysis was carried out on a group of 47 spruce and 36 beech trees, where radial stem increment at breast height - a sensitive index for stress - was measured. The ozone monitoring system allowed values to be obtained for the accumulated ozone exposure (SUM00) of each individual tree, so that their radial increment over three years could be correlated with the corresponding ozone exposure for the same time period. Correlation and regression analysis were then carried out to test the influence of ozone on diameter increment. In both spruce and beech, the initial stem diameter was the most influential factor on radial increment in the following year. A linear model was applied, including the diameter of the preceding year and the ozone exposure of the current year as predicting factors. For spruce trees, a significant negative influence of ozone exposure was found. In contrast, no significant ozone effect on diameter increment of beech was detected. The effect of ozone stress on a large spruce tree can lead to a decrease in potential radial increment of 22 %. The results are discussed in relation to other stress factors such as drought and lack of light.

Volume interpolation of CT images from tree trunks

Computerized tomography as a non-destructive scanning method to analyze wood structures has become an important technique in tree research. The possibility to reconstruct three-dimensional volumes based on a number of slices of two-dimensional data from CT scans is strongly dependent on the number of measured slices. Radial basis function methods can be successfully used to interpolate CT images with the aim of obtaining a satisfactory reconstruction of tree trunks. In contrast to standard interpolation techniques, our method takes into account that wood structures differ more in the radial than in the longitudinal direction. Therefore we obtain better interpolation results for wood structures.

Relapsing acute transverse myelitis: a specific entity

Acute transverse myelitis (ATM) not related to systemic disease may present in a relapsing manner. Data in the literature about this condition are scarce. We describe three patients suffering from relapsing myelitis in whom no association with systemic disease, i.e. infectious or connective tissue disease was found. Magnetic resonance imaging (MRI) findings were also distinctly different from multiple sclerosis and consistent with a necrotizing type of inflammation. Despite various treatment strategies, all patients became severely disabled. Relapsing ATM not related to systemic disease appears to be a specific entity which accounts for severe disability and currently lacks effective treatment.

Midbrain Ischemia Presenting as Vertical Gaze Palsy: Value of Diffusion-Weighted Magnetic Resonance Imaging

BACKGROUND

Conventional magnetic resonance imaging may fail to identify very small but clinically relevant acute subcortical brain infarcts. Diffusion-weighted magnetic resonance imaging (DWI) is very sensitive and specific for acute cerebral ischemia and should contribute to the early detection of such lesions.

METHODS

We analyzed 6 patients who presented with acute vertical gaze palsy and in whom DWI was performed within 1-6 days from symptom onset.

RESULTS

DWI accurately identified ischemia in an area supplied by the posterior thalamosubthalamic paramedian artery in all patients. T(2)-weighted and FLAIR imaging failed to identify the clinically relevant lesion in 2 and 3 patients, respectively.

CONCLUSION

DWI improves the clinicoanatomical correlation in patients presenting with supranuclear oculomotor disturbances.

TACE mRNA expression in peripheral mononudear cells precedes new lesions on MRI in multiple sclerosis

Tumor necrosis factor-alpha (TNF-alpha) is involved in the pathogenesis of multiple sclerosis (MS). It has to be released from its cell membrane-bound precursor by proteolytic cleavage. This is mainly performed by a member of the ADAM (a disintegrin and metalloproteinase) family of enzymes, TNF-alpha-converting enzyme (TACE, ADAM 17). In a longitudinal study on 11 relapsing-remitting MS patients, we qualitatively determined mRNA expression of TNF-alpha and TACE in peripheral blood mononuclear cells (PBMCs) without ex vivo stimulation. mRNA expression was related to disease activity as assessed by monthly gadolinium (Gd)-enhanced brain magnetic resonance imaging (MRI). Patients found positive for TACE mRNA in PBMCs showed a significantly higher mean number of new Gd-enhancing lesions per scan one month following PBMC sampling.

Quantitative magnetization transfer imaging of pre-lesional white-matter changes in multiple sclerosis

OBJECTIVE

Previous magnetization transfer (MT) studies in multiple sclerosis (MS) suggest a reduction of the MT ratio (MTR) precedes new lesion development. To gain further insight into pre-lesional tissue abnormalities, we investigated the time course of additional quantitative MT parameters.

METHODS

Serial magnetic resonance imaging (MRI), including a gadolinium-enhanced T1 scan and MT imaging by means of a FastPACE sequence, was performed on 12 patients (4 males, 8 females) with relapsing-remitting MS. Quantitative MT values including the magnetization exchange rate (kfor) and the native relaxation time (T1free were analysed in the six months prior to the appearance of 44 enhancing lesions and in 88 control regions of persistently normal-appearing white matter (NAWM).

RESULTS

Appearance of new active lesions was preceded by a significant decrease of the MTR (F7,166=91.5; p<0.0001) and of kfor (F7,166=105.2; p<0.0001), and by an increase of T1free (F7,166=57.3; p<0.0001). The drop of kfor was the most pronounced pre-lesional change and together with the MTR was statistically significant already four months before the appearance of new lesion. The observed increase of T1free was relatively small. MT variables of reactivated lesions were always different from NAWM but showed no characteristic time course.

CONCLUSIONS

Multiparametric MT measurements suggest both a reduction of macromolecular material and a focal increase of free water to occur several months before the appearance of an active lesion. Reduction of the magnetization exchange rate, which may result from primary damage to myelin, appears to be the leading event

[Incidental findings in cardiology. Diagnosing today what can cause illness tomorrow]

Among the anatomical and functional findings in cardiology, congenitally corrected transposition of the major vessels (ventricular inversion), bicuspid aortic valve and prolapse of the mitral valve with simultaneous mitral insufficiency have at least a potential for causing future problems. In such cases, regular cardiological checks or a further diagnostic work-up is to be recommended. The assessment of cardiac sounds can usually be correctly interpreted on the basis of the history, physical examination and auscultation. Among the electrocardiological findings, complete left bundle-branch block and prolongation of the QT segment, mandate clarification of a structural heart condition. Furthermore, in the event of ventricular extrasystoles, right-ventricular cardiomyopathy needs to be excluded. Such isolated conduction disorders as left-anterior fascicular block or right bundle-branch block are of no prognostic significance.

Magnetic resonance diffusion tensor imaging for characterizing diffuse and focal white matter abnormalities in multiple sclerosis

High-resolution diffusion tensor imaging (DTI) was performed in 14 patients with clinically definite multiple sclerosis (MS) and the trace of the diffusion tensor (<D>) and the fractional anisotropy (FA) were determined in normal appearing white matter (NAWM) and in different types of focal MS lesions. A small but significant increase of the <D> in NAWM compared to control white matter ((840 +/- 85) x 10(-6) mm(2)/sec vs. (812 +/- 59) x 10(-6) mm(2)/sec; P < 0.01) was found. In addition, there was a significant decrease in the FA of normal-appearing regions containing well-defined white matter tracts, such as the genu of the internal capsule. In non-acute lesions, the <D> of T(1)-hypointense areas was significantly higher than that of T(1)-isointense lesions ((1198 +/- 248) x 10(-6) mm(2)/sec vs. (1006 +/- 142) x 10(-6) mm(2)/sec; P < 0. 001), and there was a corresponding inverse relation of FA. Diffusion characteristics of active lesions with different enhancement patterns were also significantly different. DTI with a phase navigated interleaved echo planar imaging technique may be used to detect abnormalities of isotropic and anisotropic diffusion in the NAWM and selected fiber tracts of patients with MS throughout the entire brain, and it demonstrates substantial differences between various types of focal lesions.

Diffusion-weighted MR imaging of the spinal cord

Diffusion-weighted MR imaging may increase the sensitivity and specificity of MR imaging for certain pathologic conditions of the spinal cord but is rarely performed because of several technical issues. We therefore tested a novel phase-navigated spin-echo diffusion-weighted interleaved echo-planar imaging sequence in seven healthy volunteers and six patients with intramedullary lesions. We performed diffusion-weighted MR imaging of the spinal cord with high spatial resolution. Different patterns of diffusion abnormalities observed in patient studies support the possible diagnostic impact of diffusion-weighted MR imaging for diseases of the spinal cord.

Expression of matrix metalloproteinase-2 and -9 and their inhibitors in peripheral blood cells of patients with chronic hepatitis C

BACKGROUND

To clarify whether circulating matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) can be used as serum markers of fibroproliferation in chronic liver diseases, we studied the expression of MMP-2 and MMP-9 in relation to TIMP-1 and TIMP-2 in peripheral blood mononuclear leukocytes (MNLs) and polymorphonuclear leukocytes (PMLs), and compared this expression to circulating concentrations and hepatic histology in patients with chronic active hepatitis C (CAH).

METHODS

Quantitative reverse transcription-PCR/ELISA assays were performed for MMP and TIMP RNA, and corresponding circulating protein concentrations were studied by ELISA in 20 healthy controls, 40 patients with CAH, and 20 patients with hepatitis C-induced cirrhosis (Ci).

RESULTS

MMP-2 mRNA was found almost exclusively in the liver, MMP-9 mRNA in leukocytes. TIMP RNA-equivalents were decreased in MNLs of CAH patients, but neither MMP-9 nor TIMP RNA expression showed any correlation to the extent of inflammation and fibrosis. MMP-2 and TIMP-1 protein concentrations were increased in Ci patients and showed a wide overlap in CAH patients and healthy controls. MMP-9 values were lower in CAH and Ci patients than in healthy controls. TIMP-2 values showed a wide overlap in all three groups. The MMP-2/TIMP-1 and MMP-9/TIMP-1 ratios were lower in Ci patients than in healthy controls; the MMP-2/TIMP-2 and MMP-9/TIMP-2 ratios were not different. Circulating TIMP-1 and the MMP-2/TIMP-1 ratio correlated to the inflammatory activity in liver biopsies, but only the circulating MMP-2/TIMP-1 ratio also correlated with the degree of fibrosis.

CONCLUSIONS

Peripheral blood cell expression of MMP-2, MMP-9, and TIMP revealed no correlation with the circulating concentrations of these proteins. Only the circulating MMP-2/TIMP-1 ratio correlated to the histological degree of fibrosis in hepatitis C and should be further evaluated as a progression marker in patients with chronic liver disease.

[Indications of cerebral micro-hemorrhage in MRI. Comparative histological findings and possible clinical significance]

Increased use of gradient echo T2*-weighted gradient echo sequences in magnetic resonance imaging (MRI) of patients suffering from primary ICH called attention to foci of signal loss which were suggested to represent remnants of cerebral microbleeds. In a post mortem correlative MR and histopathological study we provide support for this notion. We found areas of signal loss on gradient echo T2*-weighted sequences in 7 out of 11 brains of patients who had died of intracerebral hematoma. Histopathologically, these areas represented hemosiderin deposits indicating previous extravasation of blood. To provide data about the prevalence of these MRI findings in a healthy elderly population a subgroup of participants of the Austrian Stroke Prevention Study was analyzed. We detected foci of signal loss on gradient echo T2*-weighted sequences in 18 out of 280 volunteers (6.4%). MR-based evidence of previous microbleeds may indicate a potentially higher risk of suffering from intracerebral bleeding which could have therapeutic implications for the treatment of acute stroke and for secondary prevention. This hypothesis will have to be tested in future prospective trials.

Expression of matrix metalloproteinase-9 and its inhibitors in mononuclear blood cells of patients with multiple sclerosis

Inflammatory mononuclear cells invading the nervous system in demyelinating diseases are supposed to be a major source of matrix metalloproteinases which are involved in damaging the blood-brain barrier and facilitating cellular migration through the extracellular matrix. Several studies revealed a crucial role of 92 kDa gelatinase (matrix metalloproteinase-9, MMP-9) in these processes. In this study, we determined MMP-9, TIMP-1 and TIMP-2 (tissue inhibitor of metalloproteinase) mRNA in peripheral blood mononuclear cells of multiple sclerosis (MS) patients by competitive reverse transcription PCR and plasma protein levels by ELISA. In active MS patients, both with relapsing-remitting and chronic progressive disease MMP-9 mRNA and plasma protein levels were significantly increased compared to healthy controls. No significant changes in mRNA expression were found for TIMP-1 and TIMP-2. However, unbound TIMP-2 in plasma was significantly higher in MS patients compared to healthy controls. MMP-9 and TIMP-1 expression was significantly correlated in MS with a significantly higher MMP-9/TIMP-1 ratio in active MS than in healthy controls. These results are in support of an important pathogenic role of MMP-9 activity in MS.

Differential expression of matrix metalloproteinases in bacterial meningitis

Matrix metalloproteinases (MMPs) are implicated in the pathogenesis of various inflammatory diseases of the central nervous system. Evidence is accumulating that gelatinase B (MMP-9) might be involved in the pathogenesis of meningitis, but the spectrum of different MMPs involved in the inflammatory reaction of this disease has not been determined. We investigated the temporal and spatial mRNA expression pattern of gelatinase B in experimental meningococcal meningitis in rats. In contrast to controls, increased mRNA levels with peak values 6 h after injection with menigococci were found in brain specimens of the animals. Elevated MMP-9 mRNA expression was accompanied by enhanced proteolytic activity, as demonstrated by gelatin zymography, and positive immunoreactivity. The mRNA expression pattern of six other MMPs was investigated. Collagenase-3 and stromelysin-1 mRNAs were also found to be upregulated. In contrast, mRNA levels for gelatinase A, matrilysin, stromelysin-2 and stromelysin-3 remained unchanged. As evidenced by significantly increased intracranial pressure and by leakage of intravenously injected Evans blue through the blood vessel walls into the brain parenchyma, the animals injected with meningococci revealed signs of blood-brain barrier disruption. Augmented proteolytic activity of MMP-9 could also be demonstrated in CSF samples obtained from patients with bacterial meningitis, underlining the clinical relevance of our experimental findings. Our data indicate that gelatinase B, collagenase-3 and stromelysin-1 are selectively upregulated in bacterial meningitis and thus may contribute to the pathogenesis of this infectious disease of the central nervous system.

Matrix metalloproteinases in inflammatory demyelination: targets for treatment

Matrix metalloproteinases (MMPs) degrade all protein components of the extracellular matrix. Functionally, they contribute to several different physiologic conditions, such as angiogenesis or bone remodeling, as well as pathologic conditions in humans, such as rheumatoid arthritis and tumor growth. MMPs seem to be important in the pathogenesis of inflammatory demyelinating diseases of the central and peripheral nervous system, especially in MS and in Guillain-Barré syndrome (GBS). Key mechanisms in the genesis of inflammatory demyelination, such as leukocyte recruitment, blood-brain barrier or blood-nerve barrier breakdown, myelin destruction, and release of disease-promoting cytokines, are considered to be MMP-dependent processes. In experimental autoimmune encephalomyelitis, an animal model of MS, and experimental autoimmune neuritis, an animal model of GBS, different synthetic inhibitors targeting MMP activity are able to suppress and even reverse ongoing disease. This evidence points to MMPs as new targets for treatment in inflammatory demyelination.

[Matrix metalloproteinases. Potential targets for new treatments in inflammatory demyelinating diseases of the nervous system]

Inflammatory demyelinating diseases of the nervous system, such as multiple sclerosis or the Guillain-Barré syndrome represent severely disabling disorders, often seen by the neurologist, with still only limited means for therapeutical intervention. The underlying pathomechanisms remain in large part elusive, however mounting evidence suggests that enzymes of the family of matrix metalloproteinases are of relevance in the pathogenesis of these disorders. Experimental in vivo data as well as results from other medical fields emphasize that the selective inhibition of these proteases could be a promising therapeutical approach. The following review summarizes the role of matrix metalloproteinases in inflammatory demyelinating diseases of the central as well as peripheral nervous system and discusses the therapeutical application of synthetic inhibitors in these disorders.

[Perioperative cost analysis of cemented versus uncemented total hip endoprostheses for clinical and economic management. Postoperative follow-up study over one year]

QUESTIONS

Are there and what are the differences between in-patient and out-patient costs for cemented or noncemented hip prosthesis? How to make it possible to keep in-patient costs within the limit of the a special global amount ("Fallpauschale")?

METHODS

In this study we compared in-patient and out-patient costs of 30 patients with cemented and 30 patients with noncemented hip prosthesis during the first year after surgery. We developed a perioperative management in order to keep the costs in the limits of the "Fallpauschale".

RESULTS

The average in-patient cost for the cemented prosthesis group was DM 19.644,89 and for the non-cemented group DM 20.485,33. In both groups these costs went beyond the "Fallpauschale" (DM 18.643,80). Comparing the two groups we found significant differences in costs for the endoprosthesis and for laboratory costs. We discovered a suitable perioperative management to keep costs below the "Fallpauschale".

CONCLUSION

Using an appropriate perioperative management it is possible to keep costs in the given limits.

[Results of testing defibrillator function of implanted cardioverter/defibrillators]

Postoperative tests of implantable cardioverter defibrillators (ICDs) are routinely performed to ensure appropriate defibrillation by the device. However, efficacy and complications of this procedure are unknown. To scrutinize the currently accepted indications to test the defibrillation function of the ICD we retrospectively analyzed 844 ICD-tests in 439 ICD-systems and 409 patients. 755 ICD-tests (89.4%) were routinely performed (57% before discharge and 43% during follow-up); 58 tests (6.9%) were performed after a change of the antiarrhythmic drug regimen, 24 tests (2.9%) after a revision of a part of the ICD-system, and seven tests (0.8%) because of a suspected dysfunction of the ICD. During routine-tests six ICD-systems (0.8%) failed to defibrillate the patient. However, in all but one test abnormalities of the ICD-system had been observed before the test. After addition of antiarrhythmic drugs, three of 58 ICD-systems (5.2%) failed to defibrillate the patient during the test (amiodarone: n = 2, flecainide: n = 1). Four of seven ICD-systems (57%) tested due to a suspected dysfunction failed to defibrillate the patient. After revisions of parts of the ICD-systems, ICD-tests never revealed a failure of defibrillation. During 16 ICD-tests (1.9%) complications occurred. The most frequent complications was inappropriate shocks (n = 10; 1.2%), the most severe one (transient) neurologic symptoms (n = 4; 0.48%). Our experience demonstrates that postoperative tests of the defibrillation function of ICDs rarely reveal ICD-dysfunction. As testing is unpleasant for the patient and not free of complications, tests might be restricted to those patients in whom an ICD-dysfunction is suspected (based on clinical presentation, results of chest-x-ray, testing of sensing signal and stimulation threshold) or class I or class III antiarrhythmic drugs have been added to the antiarrhythmic drug regimen.

Beta-blockers inhibit the modification of low-density lipoproteins by sodium hypochlorite in vitro

The effect of beta-blockers (alprenolol, oxprenolol, atenolol, acebutolol) and the non-steroidal anti-inflammatory drug, diclofenac, on modification of low-density lipoproteins (LDL) by sodium hypochlorite (NaOCl) was investigated in vitro. Beta-blockers and diclofenac inhibit the formation of thiobarbituric acid reactive substances in LDL modified by NaOCl. Beta-blockers, but not diclofenac, inhibit the hypochlorite-induced aggregation of LDL which was determined by photon correlation spectroscopy. The intracellular accumulation of cholesterol esters in J774 macrophages is inhibited by addition of beta-blockers, but not diclofenac, to LDL prior to the addition of NaOCl. The modification inhibiting effect of beta-blockers is inversely correlated to the binding capabilities of these substances to LDL which were assessed by laser electrophoresis. Inhibition of LDL modification in vivo by beta-blockers may reduce the risk of atherosclerosis and, therefore, compensate for the cholesterol-raising effect of these drugs in human plasma.

Cardiac output is not affected during intraoperative testing of the automatic implantable cardioverter defibrillator

INTRODUCTION

Perioperative mortality of patients undergoing implantation of automatic implantable cardioverter defibrillators (ICDs) has been reduced dramatically following the availability of transvenous-subcutaneous defibrillation leads. However, patients with severely reduced left ventricular function show a substantial rate of nonsudden cardiac mortality within the first year. Whether repeated intraoperative inductions of ventricular tachycardia/fibrillation (VT/VF) during implantation lead to hemodynamic deterioration and thus might contribute to development of end-stage heart failure in these patients is unknown. The purpose of the present study was to determine cardiac output and hemodynamic performance during transvenous-subcutaneous ICD implantation in patients with severe left ventricular dysfunction.

METHODS AND RESULTS

In 11 patients with a left ventricular ejection fraction (EF) < or = 0.35, cardiac output was measured automatically with a combined continuous cardiac output/mixed venous oxygen saturation pulmonary artery catheter system. ICD implantation was performed during standardized general anesthesia. In the 11 patients (EF = 27 +/- 2% [mean +/- SEM]) a total of 95 episodes of VT/VF followed by defibrillation were induced (episodes per patient = 9 +/- 1; range 6 to 11). Cardiac index was 2.2 +/- 0.2 L.min-1.m-2 after induction of anesthesia (before start of surgery), and 1.9 +/- 0.1 L.min-1.m-2 immediately before first induction of VT/VF. After the last episode of VT/VF, cardiac index was 2.1 +/- 0.2 L.min-1.m-2. Cardiac index measured 1, 2, and 3 minutes after induction of VT/VF was not significantly different when compared to the preinduction value during any episode of VT/VF induction. Similarly, stroke volume index was 39 +/- 5 mL.m-2 immediately before first induction of VT/VF and 36 +/- 3 mL.m-2 after the last episode of VT/VF (NS). At the end of surgery, hemodynamic parameters did not exhibit any significant difference when compared to the data obtained before start of ICD implantation and testing.

CONCLUSION

Extensive defibrillation tests during transvenous-subcutaneous ICD implantation in patients with severe left ventricular dysfunction are not associated with acute deterioration of cardiac performance.

Erroneous discharge of an implantable cardioverter defibrillator caused by an electric razor

We report an unusual case of the erroneous discharge of a third-generation multiprogrammable implantable cardioverter defibrillator in a 64-year-old patient with a history of recurrent ventricular tachycardias caused by electromagnetic interference while shaving with an electric razor. Electromagnetic interference was related to a defect in the electrode's insulation and could not be provoked in an intact electrode.

Method to estimate the rate and extent of intestinal absorption in conscious rats using an absorption probe and portal blood sampling

PURPOSE

A variety of methods exist which determine the rate and extent of intestinal absorption. The method described here employs an internal absorption reference probe and portal blood sampling in unanesthetized rat.

METHODS

Theophylline and tritiated water were selected as absorption reference probes since they are quantitatively absorbed in conscious rat. The fraction of an intestinal dose which reaches portal blood was determined from the resulting portal-systemic blood concentration gradients of the drug relative to the absorption probe. The absorption probes provide a means to calculate the drug mass reaching portal blood without the need of measuring the portal blood flow rate. The technique was evaluated with verapamil and a well-absorbed 5-lipoxygenase inhibitor, A-79035.

RESULTS

The fraction of an intrajejunal dose of A-79035 reaching the portal vein (FG) was 0.86 using theophylline as the absorption probe. Verapamil, which is susceptible to extensive hepatic first-pass elimination, was completely absorbed (FG = 0.98) within 1 hour, but was only 21.4% bioavailable. Absorption rate constants, estimated from initial appearance rates in portal blood, were used to monitor factors that affect drug absorption. For example, with a dose solution containing 30% PEG-400, the absorption rate constants of theophylline and A-79035 were significantly reduced. Anesthesia reduced the absorption rate constant for theophylline in rats by 40% compared to conscious animals.

CONCLUSIONS

The technique detailed here allows reliable, direct measurement of intestinal absorption which may assist in characterizing oral dosing for novel therapeutic agents.

Internal defibrillation with smaller capacitors: a prospective randomized cross-over comparison of defibrillation efficacy obtained with 90-microF and 125-microF capacitors in humans

INTRODUCTION

The size of current implantable cardioverter defibrillators (ICD) is still large in comparison to pacemakers and thus not convenient for pectoral implantation. One way to reduce ICD size is to defibrillate with smaller capacitors. A trade-off exists, however, since smaller capacitors may generate a lower maximum energy output.

METHODS AND RESULTS

In a prospective randomized cross-over study, the step-down defibrillation threshold (DFT) of an experimental 90-microF biphasic waveform was compared to a standard 125-microF biphasic waveform. The 90-microF capacitor delivered the same energy faster and with a higher peak voltage but provided only a maximum energy output of 20 instead of 34 J. DFTs were determined intraoperatively in 30 patients randomized to receive either an endocardial (n = 15) or an endocardial-subcutaneous array (n = 15) defibrillation lead system. Independent of the lead system used, energy requirements did not differ at DFT for the experimental and the standard waveforms (10.3 +/- 4.1 and 9.5 +/- 4.9 J, respectively), but peak voltages were higher for the experimental waveform than for the standard waveform (411 +/- 80 and 325 +/- 81 V, respectively). For the experimental waveform the DFT w as 10 J or less using an endocardial lead-alone system in 10 (67%) of 15 patients and in 12 (80%) of 15 patients using an endocardial-subcutaneous array lead system.

CONCLUSIONS

A shorter duration waveform delivered by smaller capacitors does not increase defibrillation energy requirements and might reduce device size. However, the smaller capacitance reduces the maximum energy output. If a 10-J safety margin between DFT and maximum energy output of the ICD is required, only a subgroup of patients will benefit from 90-microF ICDs with DFTs feasible using current defibrillation lead systems.

The signal-averaged ECG: time-domain analysis

During the past decade, the high-resolution electrocardiogram as a non-invasive technique for the detection of ventricular late potentials has developed from an experimental method into a routinely applied non-invasive method for risk stratification of patients after myocardial infarction. Meanwhile, several approaches have been developed for the detection of ventricular late potentials including time-domain analysis, frequency-domain analysis and spectrotemporal mapping. Clinical applications are no longer limited to patients after myocardial infarction, but cover a wider spectrum of different cardiac diseases. This review focuses on some methodological aspects as well as on the results and current clinical applications of the analysis of the signal-averaged ECG in the time domain.

[Reproducibility of the signal-averaged, high-pass filtered electrocardiogram]

In order to test the reproducibility of the signal-averaged electrocardiogram (SAECG) using Simson's method (high-pass filter cutoff frequency 25 Hz, orthogonal leads, recording of 133 s per lead), 121 patients were examined. In all patients, two signal-averaged ECGs were performed on the first day of the study immediately after each other, using identical electrode position. In a subgroup of 47 patients, the same procedure was repeated 3 days later. There was no difference between the mean values of conventionally calculated averaging parameters (heart rate, QRS-duration, root-mean-square voltage in the terminal 40 ms of the highly amplified and filtered QRS-complex [V40], the low amplitude signal duration under 40 microV in the terminal portion of the QRS-complex [LAS], total root-mean-square voltage of the QRS-complex), both with regard to immediate and short-term reproducibility. Thus, conventionally calculated averaging parameters are well reproducible.

Identification of abscess formation in native-valve infective endocarditis using transesophageal echocardiography: implications for surgical treatment

The object of the study was to follow patients with endocarditis-associated abscesses in order to evaluate the clinical outcome with and without surgical intervention. Transesophageal echocardiography successfully displayed the location and extent of abscess cavities in 14 patients (group A) with aortic valve endocarditis. The infective process was limited to the perivalvular tissue in two, extended into the ascending aorta in six, and included the interventricular septum, the right ventricular outflow tract, interatrial septum, and/or mitral valve annulus in six patients. The complication rate was significantly higher in group A than in group B, which consisted of 27 patients with proven signs of endocarditis but without endocarditis-associated abscesses. The complication rates were embolic events 64.3% in group A vs 29.6% in group B, need for surgery in 64.3% vs 18.5%, and death in 50.0% vs 3.7%, respectively. The duration of fever--as a marker of an active infective process--before diagnosis and the onset of adequate treatment was significantly higher in group A than in group B (46.7 +/- 8.4 days vs 7.7 +/- 2.6 days). Organisms were isolated in 71.4% in group A and in all patients of group B. Streptococcal infections were noted in A in 54.5% vs 44.4% in B., staphylococcal in 27.3% vs 40.7%. Initial surgical repair in 9 of 14 patients in A (64.3%) included nine aortic valve and one mitral valve prosthesis implantations, two aortic valve-annulus reconstructive procedures, one dacron patch closure, and three partial resections of the aorta ascendens with end-to-end anastomosis.(ABSTRACT TRUNCATED AT 250 WORDS)

[Behavior of ventricular late potentials following catheter ablation of ventricular tachycardia]

In 10 patients non-invasively recorded signal-averaged electrocardiograms were obtained before and after direct-current ablation of ventricular tachycardia (right ventricular origin n = 5; left ventricular origin n = 5). The algorithms proposed by Simson and Karbenn et al. were used (modified Frank leads, high-pass filter cut-off frequency 25 Hz). No differences were observed between the mean values of the duration of the QRS-complex, the mean voltage during the last 40 ms of the QRS-complex, the duration of the late potentials and the number of patients having late potentials before and after ablation, respectively. The success of ablation could not be predicted by the signal-averaged ECG. There was no difference between the averaging parameters of those patients without recurrences of ventricular tachycardia during the follow-up period and those with (n = 3). Thus, the signal-averaged ECG did not prove helpful in predicting a successful outcome of direct-current catheter ablation of ventricular tachycardia.

Findings with cis-Z-clopenthixol in the treatment of acute mania and schizophrenia

The authors report the results of an open clinical trial with Cis(Z)-Clopenthixol (Cisordinol), the isolated Cis-isomer of the Clopenthixol racemate (Sordinol). The drug was applied to 18 patients with severe forms of manic or schizophrenic disease, diagnosed according to ICD 9. The compound was applied intravenously or orally, daily doses ranging from 10-160 mg. For the duration of the study (6 weeks) the patients were repeatedly rated with the CGI, BPRS or IMPS (abbreviated version), and several hematological and enzyme patterns, cardiac, renal function and electrolytes were monitored, as was the FFA. Due to the relatively small number of patients in relatively heterogeneous diagnostic composition, a number of items rated failed to reach statistical significance. The CGI showed a good therapeutic effect with a minimal incidence or severity of side effects. BPRS and IMPS documented an impressive decline in formal thought-disorders, agitation, logorrhea and tenseness. The sedative effects of the drug were slight and of short duration, anti-Parkinson medication was necessary in more than 50% of the patients studied. The results of the study show a good efficacy of the drug in manic and schizophrenic disorders, Cisordinol being well tolerated intravenously. The range of doses administered is approximately 50% of the dose-range of the parent-drug (Sordinol).