The endocannabinoid system controls key epileptogenic circuits in the hippocampus

Balanced control of neuronal activity is central in maintaining function and viability of neuronal circuits. The endocannabinoid system tightly controls neuronal excitability. Here, we show that endocannabinoids directly target hippocampal glutamatergic neurons to provide protection against acute epileptiform seizures in mice. Functional CB1 cannabinoid receptors are present on glutamatergic terminals of the hippocampal formation, colocalizing with vesicular glutamate transporter 1 (VGluT1). Conditional deletion of the CB1 gene either in cortical glutamatergic neurons or in forebrain GABAergic neurons, as well as virally induced deletion of the CB1 gene in the hippocampus, demonstrate that the presence of CB1 receptors in glutamatergic hippocampal neurons is both necessary and sufficient to provide substantial endogenous protection against kainic acid (KA)-induced seizures. The direct endocannabinoid-mediated control of hippocampal glutamatergic neurotransmission may constitute a promising therapeutic target for the treatment of disorders associated with excessive excitatory neuronal activity.

Anxiety and hippocampus volume in the rat

In depressed patients as well as healthy controls, a positive relationship between hippocampal volume and trait anxiety has been reported. This study sought to explore the possible inter-relation between hippocampal volume and trait anxiety further. Magnetic resonance imaging at 7 T was used to measure hippocampal volumes in a rat model of extremes in trait anxiety (experiment 1) and in a Wistar population with normal anxiety-related behavior (experiment 2). In addition to anxiety-related behavior, potentially confounding factors (depression-like, exploratory, and locomotor behavior) were assessed. Experiment 1 globally supported the hypothesis of a positive relationship between hippocampus volume and trait anxiety but did not allow for ruling out possible confounds arising from cosegregation of other behavioral traits. Experiment 2 yielded strong evidence for a negative relationship which was specific for trait anxiety. Thus, the relationship between hippocampal volume and anxiety may be more complex than expected. Interestingly, anxiety-related behavior in experiment 2 had a stronger influence on hippocampal volume than depression-like behavior. In the light of hippocampal volume loss in anxiety disorder and frequent comorbidity of anxiety and depression, this finding suggests that further research into the relationship between anxiety and hippocampal volume may be critical for understanding hippocampal contributions to normal and pathological behavior.

Determination of tumour prognosis based on angiogenesis-related vascular patterns measured by fractal and syntactic structure analysis

AIMS

Intratumoural micro-vessel density (IMD) has recently been shown to be a valuable prognostic tool in many tumours. Yet, IMD does not take into account the spatial arrangement of the vessels, therefore only partly reflecting the angiogenic situation. In order to describe contextual vascular relationships more accurately, we have used fractal and syntactic structure analysis (SSA) based on computerised image processing to quantify micro-vascular hot spots.

MATERIALS AND METHODS

The parametric performance in prediction of patients' outcome was evaluated by univariate analysis and compared with manually obtained IMDs, whereas an automated K-nearest-neighbour (KNN) classifier searched most discriminative parametric combinations. The method is based on analysis of vascular 'hot-spots' of paraffin-embedded tissue sections of invasive cervical carcinoma, colorectal carcinoma and malignant mesothelioma.

RESULTS

For all three cancers, prediction of prognosis based on SSA yielded in general much higher recognition scores compared with IMD or fractal dimension. Survival of cervical carcinoma was mostly correlated with clinical data, with the vascular permeation being the only parameter with independent value. Prognosis of colorectal carcinoma is best described by SSA, completed with IMD, indicating an inverse correlation of survival time with a more irregular pattern and a slight increase in vessel number. For mesothelioma, we found a strong correlation with SSA and patients' outcome, with two SSA-parameters having independent prognostic value.

CONCLUSIONS

The more accurate angiogenic description obtained with SSA may be useful for further exploitation as a prognosticator in a general diagnostic pathology service.

Learned association of allocentric and egocentric information in the hippocampus

Single-cell recording was conducted in the hippocampus of rats that performed a spontaneous alternation task in a modified T-maze. In the central arm of the maze, 4 out of 45 cells (8%) were found that fired selectively depending on which turn the animals would take. This result is in disagreement with a previous study in which two-thirds of cells (22 out of 33) showed a clear bias for direction of turns. The interpretation was that the cells coded information of episodic memory. Our results do not support this hypothesis. Interestingly, over the course of training, an increasing number of cells were found that fired in correlation with the rats' movements. It is proposed that these cells associate egocentric motor information with allocentric spatial information rather than encode episodic memory.

Reward modulates neuronal activity in the hippocampus of the rat

In the hippocampus of freely moving rats, neurons have been recorded that fire predominantly when the animal travels through a particular area while exploring the environment (so-called 'place cells'). This study investigates if the neuronal firing characteristics of such cells are modulated by attention, expectation of reward or memory load. A total of 16 electrodes were implanted in the CA1 region of the hippocampus of 3-month-old Long-Evans rats. Using a tetrode recording system, single neurons were recorded while a rat explored an 8-arm maze and retrieved pellets at the end of each arm. It was found that 31 out of 67 neurons showed place cell characteristics, while the other cells either fired in more than one place or fired along whole arms of the maze. Interestingly, 11 of the 31 neurons showed enhanced firing activity when the animal entered a baited arm but did not fire when the arm was visited again after the bait had been retrieved. In a second experiment, only four out of eight arms were baited. Firing rates of 46 neurons were analysed, and all cells (spatial or non-spatial) fired more in baited arms than in non-baited ones (P<0.001). In a reversal task in which the previously unbaited four arms were subsequently baited, neuronal activity was increased in the newly baited arms (42 cells analysed, P<0.001). Since no alterations to the maze or cues have been made, we interpret the increased firing probability of neurons in baited arms compared to unbaited arms as a correlate for 'attention' or 'expectation'.

Validation of nuclear texture, density, morphometry and tissue syntactic structure analysis as prognosticators of cervical carcinoma

OBJECTIVE

To evaluate the performance of karyometry and histometry in the prediction of survival, recurrence and response of early-stage invasive cervical carcinoma.

STUDY DESIGN

Nuclear morphometry, chromatin texture and tissue architecture (characterized by syntactic structure analysis) were measured using a semiautomated image analysis system on 46 cases of Feulgen-stained tissue sections. The performance of the features was compared to that of clinical features, reported to be the best prognosticators until now, such as age, lympho-vascular permeation, histologic type, stage and grade. A K nearest neighbor classifier was used for classification.

RESULTS

In the prediction of three-year survival, recurrence and response, syntactic structure analysis proved to be the best performer. Classification rates were, respectively, 100%, 94.4% and 94.5%. In all classifications, karyometric and histometric features outperformed clinical features. In general, the best performing features described differences in second-order population statistics (standard deviations).

CONCLUSION

The results show that a quantitative analysis based on nuclear morphology, chromatin texture and histology can be considered an excellent aid in the prognosis of invasive cervical carcinoma. The measurements are not hampered by the need to undertake complete resections and are suited to daily practice when implemented in a semiautomated image analysis system.

Data representation and reduction for chromatin texture in nuclei from premalignant prostatic, esophageal, and colonic lesions

BACKGROUND

To identify nuclei and lesions with great specificity, a large set of karyometric features is arranged in the form of a linear profile, called a nuclear signature. The karyometric feature values are normalized as z-values. Their ordering along the profile axis is arbitrary but consistent. The profile of the nuclear signature is distinctive; it can be characterized by a new set of variables called contour features. A number of data reduction methods are introduced and their performance is compared with that of the karyometric features in the classification of prostatic, colonic, and esophageal lesions.

METHODS

Contour characteristics were reduced to descriptive statistics of the set of z-values in the nuclear signature and to sequence information. The contour features derived were (1) relative frequencies of occurrence of z-values and of their differences and (2) co-occurrence statistics, run lengths of z-values, and statistics of higher-order dependencies. Performance was evaluated by comparing classification scores of diagnostic groups.

RESULTS

Rates for correct classification by karyometric features alone and contour features alone indicate equivalent performance. Classification by a combined set of features led to an increase in correct classification.

CONCLUSIONS

Image analysis and subsequent data reduction of nuclear signatures of contour features is a novel method, providing quantitative information that may lead to an effective identification of nuclei and lesions.

Wavelets as chromatin texture descriptors for the automated identification of neoplastic nuclei

Chromatin distribution reflects the organization of the DNA of a nucleus and contains important cellular diagnostic and prognostic information. Feulgen staining of breast tissue enables the chromatin distribution of the nucleus to be visualized in the form of texture. Describing texture in an objective and quantitative way by means of a set of texture parameters, combined with the study of the relationship of such parameters to the pathobiological cell properties, is useful both for reduction of the subjectivity inherently coupled to visual observation and for more accurate prognosis or diagnosis. We have presented an automated classification scheme for the diagnosis and grading of invasive breast cancer. The input to this scheme was a digitized microscopical image, from which nuclei were segmented. Chromatin texture was described using a set of textural parameters that include first- and second-order statistics of the image grey levels. The more recently developed wavelet energy parameters were also included in our study. Classification was performed by a Knn-classifier, which is a versatile multivariate statistical classification technique. We investigated the role of the tissue preparation technique and found that parameters derived from cytospins were better texture descriptors than those from sections. A 100% correct classification was achieved in a patient diagnosis experiment and 82% in a nuclear grading experiment.

Value of morphometry, texture analysis, densitometry, and histometry in the differential diagnosis and prognosis of malignant mesothelioma

Malignant mesothelioma is a tumour with increasing incidence due to widespread use of its causative agent, asbestos, in the past decades. The poor survival necessitates a correct differentiation from other lesions at the same site, such as hyperplastic mesothelium and carcinomas metastatic to pleura or peritoneum. Since genetic and immunohistochemical markers are not absolutely differentiating, the diagnosis is based on the histology complemented with (immuno)histochemistry. However, as the tumour presents itself in numerous heterogeneous histological forms, visual evaluation is extremely difficult. In order to evaluate the prognostic and diagnostic performance of syntactic structure analysis (SSA), chromatin texture analysis, densitometry, and morphometry, an automated KNN-classification system has been used to compare Feulgen-stained tissue sections of hyperplastic mesothelium, malignant mesothelioma, and pulmonary adenocarcinoma. In addition, we also studied most discriminative aspects in the differentiation, typing, and prediction of survival. The results indicate that for the diagnosis of malignant mesothelioma, chromatin texture parameters outperform SSA, densitometry, and morphometry (recognition score=96.8 per cent). Most discriminative parameters highlight spatial patterns of the chromatin distribution that are hard to appraise visually and directly show the benefits of a quantitative approach. Typing of the tumour is best described by SSA parameters, relating to the spatial arrangement of the cells in the tissue (recognition score=94.9 per cent). In survival time classifications, chromatin texture yields the highest recognition score (82.9 per cent), although accurate estimations are unreliable due to a large degree of misclassification.

Computer-assisted differential diagnosis of malignant mesothelioma based on syntactic structure analysis

BACKGROUND

Malignant mesothelioma, a mesoderm-derived tumor, is related to asbestos exposure and remains a diagnostic challenge because none of the genetic or immunohistochemical markers have yet been proven to be specific. To assist in the identification of mesothelioma and to differentiate it from other common lesions at the same location, we have tested the performance of syntactic structure analysis (SSA) in an automated classification procedure.

MATERIALS AND METHODS

Light-microscopic images of tissue sections of malignant mesothelioma, hyperplastic mesothelium, and adenocarcinoma were analyzed using parameters selected from the Voronoi diagram, Gabriel's graph, and the minimum spanning tree which were classified with a K-nearest-neighbor algorithm.

RESULTS

Results showed that mesotheliomas were diagnosed correctly in 74% of the cases; 76% of the adenocarcinomas were correctly graded, and 88% of the mesotheliomas were correctly typed. The performance of the parameters was dependent on the obtained classification (i.e., tumor-tumor versus tumor-benign).

CONCLUSIONS

Our results suggest that SSA is valuable in the differential classification of mesothelioma and that it supplements a visually appraised diagnosis. The recognition scores may be increased by a combination of SSA with, for example, cellular or nuclear parameters, measured at higher magnifications to form a solid base for fully automated expert systems.

Modulation of mitochondrial contact sites formation in immature rat heart

Creatine phosphokinase-mediated transport of energy from the site of production to the site of consumption is a key process for meeting the energy-demands of reactions in cytosol. The mitochondrial creatine phosphokinase (mCPK) plays an important role in this process, with the enzyme activity localized particularly in the mitochondrial contact sites (MiCS). Earlier studies in adult animals have shown that the formation of MiCS varies in response to the energy demand and the physiological state of the heart, and it is stimulated by an increase in [Ca2+]i. However, there is little known about MiCS formation in juvenile hearts, characterized by metabolism different from adult hearts. In the present study we investigated the modulation of MiCS formation via Ca2+ in hearts of 14-day-old rats. The moderate response of MiCS to various stimuli (elevated extracellular Ca2+, diltiazem, cardiac arrest by Cd2+) may refer to a still increased intracellular Ca2+ concentration, the incomplete development of mitochondrial energy production as well as to persistingly high energy demand of the developing heart.

Applications of laser microprobe mass spectrometry in biology and medicine

Laser microprobe mass spectrometry (LMMS) provides spot analysis with a lateral resolution of 1-5 microns. Focused laser ionisation, combined with mass spectrometry, yields information on elements, molecular identification of inorganic substances, and structural characterisation of organic molecules of typically less than 2-3 kDa. Quantification in complex heterogeneous systems, such as biological materials, is not possible at the present state of the art. The strength of the method lies in the qualitative information on the molecular composition of the analyte, not just element detection, with a lateral resolution at the light microscopy level. The applications of this technique in the field of biomedicine and biology are illustrated by examples that demonstrate the use of this qualitative information in practical test cases.

Automated breast tumor diagnosis and grading based on wavelet chromatin texture description

In this paper, wavelets were employed for multi-scale image analysis to extract parameters for the description of chromatin texture in the cytological diagnosis and grading of invasive breast cancer. Their value was estimated by comparing the performance of co-occurrence, densitometric, and morphometric parameters in an automated K-nearest neighbor (Knn) classification scheme based on light microscopic images of isolated nuclei of paraffin-embedded tissue. This design allowed a multifaceted cytological retrospective study of which the practical value can be judged easily. Results show that wavelets perform excellently with classification scores comparable with densitometric and co-occurrence features. Moreover, because wavelets showed a high additive value with the other textural groups, this panel allowed a very profound description with higher recognition scores than previously reported (76% for individual nuclei, 100% for cases). Morphometric parameters performed less well and only slightly increased correct classification. The major drawback, besides image segmentation errors demanding operator supervision, emanated to be the few false-negative cases, which restrict the immediate practical use. However, an enlargement of the parameter set may avoid this misclassification, resulting in an applicable expert system of practical use.

Cytoarchitectural and metabolic adaptations in muscles with mitochondrial and cytosolic creatine kinase deficiencies

We have blocked creatine kinase (CK) mediated phosphocreatine (PCr) <==> ATP transphosphorylation in mitochondria and cytosol of skeletal muscle by knocking out the genes for the mitochondrial (ScCKmit) and the cytosolic (M-CK) CK isoforms in mice. Animals which carry single or double mutations, if kept and tested under standard laboratory conditions, have surprisingly mild changes in muscle physiology. Strenuous ex vivo conditions were necessary to reveal that MM-CK absence in single and double mutants leads to a partial loss of tetanic force output. Single ScCKmit deficiency has no noticeable effects but in combination the mutations cause slowing of the relaxation rate. Importantly, our studies revealed that there is metabolic and cytoarchitectural adaptation to CK defects in energy metabolism. The effects involve mutation type-dependent alterations in the levels of AMP, IMP, glycogen and phosphomonoesters, changes in activity of metabolic enzymes like AMP-deaminase, alterations in mitochondrial volume and contractile protein (MHC isoform) profiles, and a hyperproliferation of the terminal cysternae of the SR (in tubular aggregates). This suggests that there is a compensatory resiliency of loss-of-function and redirection of flux distributions in the metabolic network for cellular energy in our mutants.

Apoptosis and related proteins in different stages of human atherosclerotic plaques

BACKGROUND

The transition of a fatty streak into an atherosclerotic plaque is characterized by the appearance of focal and diffuse regions of cell death. We have investigated the distribution of apoptotic cell death and apoptosis-related proteins in early and advanced atherosclerotic lesions.

METHODS AND RESULTS

Human atherosclerotic plaques were studied by whole-mount carotid endarterectomy specimens (n=18). This approach allowed comparison of adaptive intimal thickenings, fatty streaks, and advanced atherosclerotic plaques of the same patient. The fatty streaks differed from adaptive intimal thickenings by the presence of BAX (P<0.01), a proapoptotic protein of the BCL-2 family. Both regions were composed mainly of smooth muscle cells (SMCs), and macrophage infiltration was low and not different. Apoptosis, as detected by DNA in situ end labeling (terminal deoxynucleotidyl transferase end labeling [TUNEL] and in situ nick translation) was not present in these regions. Apoptosis of SMCs and macrophages, however, was present in advanced atherosclerotic plaques that were present mainly in the carotid sinus. A dense infiltration of macrophages (5.8+/-3% surface area) was present in these advanced atherosclerotic plaques. Cytoplasmic remnants of apoptotic SMCs, enclosed by a cage of thickened basal lamina, were TUNEL negative and remained present in the plaques as matrix vesicles.

CONCLUSIONS

We conclude that SMCs within human fatty streaks express BAX, which increases the susceptibility of these cells to undergo apoptosis. The localization of these susceptible SMCs in the deep layer of the fatty streaks could be important in our understanding of the transition of fatty streaks into atherosclerotic plaques, which are characterized by regions of cell death. Matrix vesicles are BAX-immunoreactive cytoplasmic remnants of fragmented SMCs that can calcify and may be considered the graves of SMCs that have died in the plaques.

A closed culture system for the ex vivo transduction and expansion of human T lymphocytes

A phase I clinical trial is currently being performed at our institution, with the aim of evaluating the feasibility and toxicity related to the administration of herpes simplex thymidine kinase gene-expressing human primary T lymphocytes following allogeneic hematopoietic stem cell transplantation. The need for safe and standardized preparation conditions for gene-modified cells is crucial. We describe the closed culture system used in the current trial for ex vivo retroviral-mediated gene transfer and transduced cell selection. Cell handling is performed in closed systems using a sterile connection device that avoids opening the culture system. Cell numbers during the production process increased from 93 +/- 16 on day 0 to 440 +/- 92 x 10(6) on day 12 (7.2 +/- 1.4-fold increase) (n = 11). Transduction efficiency before and after G418 resistance-based selection was 13.5 +/- 3.8% and 90.0 +/- 1.4%, respectively. Safety and efficacy testing included a search for replication-competent retrovirus, endotoxins, Mycoplasma, and bacterial contamination (n = 0/9), PCR-DNA, % CD3+ cells (91 +/- 2%), and viability after thawing (82 +/- 3%). Effective working time from day 0 to day 12 is approximately 20 h. The closed system we developed allows for safe and reproducible ex vivo preparation of gene-modified primary T lymphocytes for clinical use.

Atomic force microscopy: influence of air drying and fixation on the morphology and viscoelasticity of cultured cells

The influence of fixation, air-drying and liquid-imaging on the morphology as well as on the viscoelasticity of malignant mesothelioma cells was studied by atomic force microscopy. In this study, dehydrated cells were more easily scanned and offered faster data recording than hydrated cells. However, the influence of fixation strength was more noticeable. Strong fixation induced flattening of the cytoplasm and loss of nuclear structure, resulting in a clearly visible cytoskeleton which could be easily seen as fibres orientated in the direction of the cell growth. By contrast, the morphology of hydrated cells was influenced to a lesser degree on fixation and showed an overall 'rounding' of the surface with vague, ill-defined structures. Nuclear areas of these samples were difficult to image. Viscoelasticity measurements also exhibited large differences. Dehydrated cells were much harder and showed a uniform indentation profile over the whole cell that was independent of fixation. Indentation on hydrated cells was large and depended on the height of the measuring spot, the submembranous structure and, to a lesser extent, on fixation. To calculate an overall 'cellular' viscoelasticity, different methods were tested on these samples. Indentations of multiple, randomly chosen points, covering the whole cell, were measured and averaged to yield a mean indentation score. We avoided the thin and shadowed areas since it was shown that these regions were less suited for measuring. Using this design, large viscoelasticity differences were found, on which the influence of the external parameters could be shown. In another set-up, layered imaging was tried. However, long data acquisition times caused cellular activation and rearrangement, making this scanning mode unsatisfactory.

Retrovirus-mediated transfer of the herpes simplex type I thymidine kinase gene in alloreactive T lymphocytes

We have demonstrated in previous studies that retrovirus-mediated transfer of the herpes simplex thymidine kinase (HS-tk) and neomycin phosphotransferase (neo) genes in CD3/IL-2 stimulated primary T lymphocytes followed by G418 selection resulted in T cells retaining both interleukin-2 (IL-2) and alloresponsiveness and specifically inhibited by ganciclovir (GCV). A clinical trial examining the therapeutic potential of such gene-modified donor T cells after allogeneic bone marrow transplantation is presently underway. In the present study, we have investigated the feasibility and consequences of replacing polyclonal stimulation of T cells by an allogeneic stimulation prior to retrovirus-mediated gene transfer. Exposure of allostimulated primary donor T lymphocytes to retrovirus-containing supernatant resulted in T cells resistant to G418 while maintaining a strong, GCV-sensitive, allogeneic response when subsequently restimulated with the initial allogeneic cells. Control nontransduced cells identically stimulated exhibited a weaker, GCV-insensitive, allogeneic proliferative response. The transduced T cells were also capable of GCV-sensitive alloreactivity when exposed to third-party cells with, however, a lower proliferative response than that seen with the allogeneic cells used for stimulation at the time of transduction. Importantly, this difference in the proliferative responses was not observed with control nontransduced cells identically stimulated. A similar response pattern was observed with respect to pre-cytotoxic T lymphocyte (CTL) frequencies. Overall, retrovirus-mediated gene transfer after an allogeneic stimulation can lead to efficient transduction and the pattern of alloreactivity of the HS-tk-expressing cells is consistent with the preferential transduction of alloantigen-specific dividing T cells. Such an approach could be used to generate cells both strongly alloreactive and GCV-sensitive for in vivo therapeutic use.

Rab3 dissociation and clathrin-mediated endocytosis, two key steps in the exo-endocytotic pathway of large dense-cored vesicles in primary cultures of superior cervical ganglia

In this study we have used primary cultures of porcine superior cervical ganglia as a model system to study exo-endocytosis in sympathetic neurons. Pure neuronal cultures with a defined noradrenergic phenotype can be obtained when antimitotics are included in the culture medium, and the high yield from prenatal piglets allows a biochemical approach in addition to morphological studies. Release of large dense-cored vesicles (LDCVs) was visualized by exposing stimulated neurons to anti-dopamine-beta-hydroxylase (D beta H) prior to fixation. Double immunofluorescent staining revealed that synaptotagmin was colocalized with anti-D beta H labeled exocytotic spots, but not the small GTP-binding protein rab3. Density gradient centrifugation of a postmitochondrial supernatant of cultured cells confirmed the dissociation of rab3 from a population of mature LDCVs. As expected, rab3 did not reassociate with the lighter D beta H-positive membrane fraction in the gradient representing internalized LDCV membranes. The fluid phase marker horseradish peroxidase colocalized with retrieved LDCV membranes. Indirect immunofluorescence demonstrated the colocalization of clathrin with D beta H-positive exocytotic spots on the plasma membrane. At the ultrastructural level, depolarization of neurons resulted in the abrupt loss of LDCVs and concomitant appearance of clathrin-coated vesicles and coated omega profiles. The size distribution of coated structures overlapped strongly with that of LDCVs. Taken together, these data clearly suggest that two key regulatory events in the process of exo-endocytosis, i.e. rab3 dissociation and clathrin-mediated internalization, are not only reminiscent of small synaptic vesicles, but also are a feature of the LDCV pathway at the presynaptic plasma membrane of sympathetic neurons.

Diagnostic classification through the study of linguistic dimensions

28 patients (17 with lung cancer and 11 with tuberculosis) were analyzed for patterns in their speech which were then compared with those found in healthy control subjects, using a computerized method called RELATEX/RELATAN. The results suggest that speech of patients with tuberculosis expresses evaluations and attitudes more often than that of lung cancer patients and healthy controls. It appears that the computer-oriented method RELATEX/RELATAN can be useful in psycholinguistic research. Suggestions for further research are given.

Luminal foam cell accumulation is associated with smooth muscle cell death in the intimal thickening of human saphenous vein grafts

BACKGROUND

Occlusion of saphenous vein grafts is a major problem after coronary artery bypass graft surgery. Diffuse intimal thickening develops in all implanted aortocoronary saphenous vein grafts within 6 months to 1 year. In some regions of the thickened intima, foam cells accumulate along the luminal margin. This particular morphology resembles the morphology of unstable atherosclerotic plaques as they occur in coronary arteries. In the present study, we focused on the possible topographic relation between luminal foam cell accumulation and cell death of smooth muscle cells (SMCs) within the adjacent thickened intima.

METHODS AND RESULTS

Segments of occluded and suboccluded implanted human aortocoronary saphenous vein grafts were obtained during reintervention coronary artery bypass graft surgery in 30 patients. In the regions of the vein grafts with luminal foam cell accumulation, the percentage of SMC alpha-actin immunoreactive area of the superficial intimal thickening was 6 +/- 1.4%, which was different from the 17.6 +/- 2.3% of the deep intimal thickening. A strong negative correlation between the number of foam cell nuclei and the percentage of SMC alpha-actin immunoreactive area in the adjacent superficial intimal thickening was present (r = -.77, P < .001). Within the superficial intimal thickening, cytoplasmic and DNA fragmentation could be detected, which points to apoptotic cell death. A fraction of the cytoplasmic fragments fitted the ultrastructural characteristics of matrix vesicles and showed pronounced calcium and phosphorus accumulation as demonstrated with the use of x-ray microanalysis.

CONCLUSIONS

The close spatial relation among foam cell accumulation, pronounced intimal SMC loss, and cell death suggests the presence of a foam cell-derived factor that can induce cell death in the SMC population of the intimal thickening. The depletion of the intimal SMC population could promote plaque rupture and thrombotic complications in the grafts.

Biotin- or digoxigenin-conjugated nucleotides bind to matrix vesicles in atherosclerotic plaques

The present study analyzes the staining pattern of DNA in situ end-labeling techniques of human and rabbit atherosclerotic plaques. Both the terminal deoxynucleotidyl transferase end-labeling and the in situ nick translation technique detected, besides apoptotic nuclei, numerous round vesicles with diameters from 0.5 to 5 microns within the atherosclerotic plaques. These vesicles did not contain DNA but contained calcium. A pretreatment with EDTA or citric acid abolished the labeling of the vesicles but did not influence the detection of apoptotic nuclei. Ultrastructurally, the vesicles were of variable diameter and density, and their aspect was compatible with matrix vesicles, which are well known in epiphyses during bone formation. The larger vesicles contained cell organelles, and the small vesicles were very dense. X-ray microanalysis demonstrated high calcium and phosphorus levels within the most dense vesicles. Different stages of the process were present in the plaques. In this way we could demonstrate that cytoplasmic fragmentation of smooth muscle cells and subsequent formation of matrix vesicles are a frequent finding in atherosclerotic plaques. The association of apoptotic cell death and formation of matrix vesicles could be an interesting pathway in explaining calcification of atherosclerotic plaques. Both the terminal deoxynucleotidyl transferase end-labeling and the in situ nick translation technique detected simultaneously apoptotic nuclei and matrix vesicles if calcium is not removed from the sections.

Destruction of lacis cells of the juxtaglomerular apparatus in the hypercholesterolemic rabbit

During a study of experimentally induced atheromatosis in hypercholesterolemic rabbits we found a heavy infiltration of the lacis cell field (G field) by lipids in the kidney. A systematic study was done in 12 rabbits receiving a dietary cholesterol supplement of 0.3% for 26 weeks and in 8 animals receiving a supplement of 2% for 8 weeks. Standard histology, immunohistochemistry for a-smooth muscle cell actin and with the macrophage specific antibody RAM 11, and transmission electron microscopy were performed. In the low cholesterol, long duration group, 90% of the G fields were involved. The lipid accumulation was mainly extracellular. The lacis cells contained moderate numbers of medium sized lipid vacuoles and showed signs of cytoplasmic damage leading to disintegration. The mesangial cells contained few dipid droplets and the matrix was normal. The arterioles were not involved. The lesion suggests an impairment of the clearance of lipids, leading to interstitial accumulation and cellular damage.

New calibration method for the determination of the absolute density of CH radicals through laser-induced fluorescence

Laser-induced fluorescence (LIF) was applied at the B-X transition of the CH radical to measure the absolute densities of CH radicals in an electron-cyclotron resonance methane plasma. The absolute experimental uncertainty is only approximately 30% as a result of a new calibration procedure. The experimental setup was calibrated through the comparison of the LIF signal of N(2)(+) with that of CH. The absolute N(2)(+) density was derived from the spatially resolved N(2)(+) LIF signal and the line-averaged electron density as measured with microwave interferometry.

Bronchoscopic insufflation of room air for the treatment of lobar atelectasis in mechanically ventilated patients

Segmental and lobar pulmonary atelectasis is a common occurrence in mechanically ventilated patients. Standard therapy for atelectasis relies on positive pressure ventilation, positive and expiratory pressure (PEEP), tracheobronchial toilet and regular chest physiotherapy. Various adjuncts to physiotherapy such as bronchoscopic clearance of secretions have not proved to be of additional benefit. Bronchoscopic clearance of secretions followed by insufflation of room air at 30 cm H2O into the atelectatic segment was employed on ten occasions in mechanically ventilated patients. Rapid re-expansion of the collapsed segment or lobe occurred in seven out of the ten treatments.

The effect of ischemia and reperfusion on mitochondrial contact sites in isolated rat hearts

Contact sites may be described as energy channels between the mitochondria and the cytosol, created by fusion of the inner and the outer mitochondrial membranes, and their number depends highly on the energy state of the cell. The aim of the present study was to examine the early changes of ischemia and reperfusion on the number of mitochondrial contact sites. Therefore isolated rat hearts were subjected to short periods of ischemia followed by reperfusion. The left ventricular pressure (LVP), the contractility (dP/dtmax) and the heart rate were measured. The number of contact sites was morphometrically evaluated. As the flow was stopped, LVP, dP/dtmax and HR declined rapidly and became undetectable after 2 min of ischemia. The number of contact sites fell to a minimum after 10 min of ischemia after an initial increase (1 min of ischemia). A 15 min ischemic period resulted in a high number of contact sites which decreased again after 20 min of ischemia. Reperfusion after 2 min of ischemia caused an immediate functional recovery and a high presence of contact sites. After 15 min of reperfusion, all values returned to control values. Reperfusion after 10 min of ischemia resulted in a slow recovery of the number of contact sites and after 15 min of ischemia the number of contact sites remained low upon reperfusion. We may conclude that mitochondria lose the ability to form contact sites after more than 15 min of ischemia and this might be a first indication of irreversible injury.

Lidocaine does not prevent the calcium paradox in rat hearts: a laser microprobe mass analysis (LAMMA) study

The calcium paradox stands for the cell damage that occurs when isolated hearts are perfused with a Ca(2+)-free solution followed by perfusion with a Ca(2+)-containing solution. Although it is generally accepted that a massive Ca2+ influx during the Ca(2+)-repletion phase is responsible for the cell damage, there is no consensus about what makes the heart susceptible to the calcium paradox during the Ca(2+)-depletion phase. It has been suggested that the extent of the calcium paradox is primarily determined by accumulation of Na+ during Ca2+ depletion and a subsequent accumulation of Ca2+ via reverse Na(+)-Ca2+ exchange during Ca2+ repletion. According to another theory, weakening of intercalated disc junctions during Ca2+ depletion and contracture-mediated disruption of the cell membrane during Ca2+ repletion are responsible for the calcium paradox. In the present study we further investigated the possible role of Na+ in the development of the calcium paradox. During Ca2+ depletion, lidocaine was used to inhibit Na+ entry through the Na+ channels. Isolated rat hearts were perfused with Krebs Henseleit buffer (KH) containing 1.4 mM Ca2+ for 15 min, followed by 10 min of Ca(2+)-free perfusion and 10 min of reperfusion with Ca2+. In the treated group 0.1 mM lidocaine was present throughout the experiment. At the end of each experiment, Ca2+ cytochemistry was performed and the intracellular Ca2+ content was analyzed by laser microprobe mass analysis (LAMMA). The results show that during Ca2+ depletion, the intracellular Ca2+ content did not change significantly. Ca2+ repletion, however, gave rise to a full calcium paradox irrespective of the presence of lidocaine: massive cell damage and Ca2+ accumulation in the mitochondria. The results provide further evidence that intracellular Na+ accumulation during Ca2+ depletion is not involved in the occurrence of the calcium paradox.

The effect of calcium on mitochondrial contact sites: a study on isolated rat hearts

Mitochondrial contact sites are dynamic structures created by fusion of the inner and outer mitochondrial membranes. Stimulation of the metabolism results in an increase of the number of contact sites. Functionally, it is shown that mitochondrial creatine kinase (Mi-CK) is active in contact sites and therefore, Mi-CK cytochemistry was performed (using a tetrazolium salt) to improve the visibility of the contact sites. As calcium is involved as an intracellular messenger of hormonal stimulation, the effect of increasing extracellular calcium concentrations on the number of contact sites was investigated. Therefore, isolated rat hearts were perfused with Krebs-Henseleit buffers differing in their calcium content. During the perfusions the heart function was evaluated and at the end of each experiment, the hearts were processed for Mi CK cytochemistry and the number of contact sites was expressed as the ratio of surface densities contact sites to mitochondrial membranes (Ss). At 2.2 mM calcium perfusion, the physiological parameters and the Ss reached a maximum. This was in contrast to the 0.6 and the 3.6 mM of calcium perfusions whereby both the physiological values and the Ss were decreased. Treatment with noradrenaline in vivo, as was done in previous studies or perfusion with 2.2 mM of calcium ends up with similar values for Ss. From these results, it could be suggested that there might be a link between calcium, heart function and the formation of Mi CK active contact sites.

Co-storage in large 'dense-core' vesicles of dopamine and cholecystokinin in rat striatum

The subcellular localization of cholecystokinin in the striatum--an area where a high density of cholecystokinin containing terminals has been demonstrated--was studied using biochemical techniques. Cholecystokinin containing vesicles were partially purified using iso-osmotic Ficoll gradients. As judged from their size and their buoyant density in isopycnic gradients, cholecystokinin containing vesicles represent large 'dense-core' vesicles. Negative staining and subsequent immunolabelling for synaptophysin at the electron microscopical level, showed labelled vesicles of 50-70 nm. binding of dihydrotetrabenazine was detected in the cholecystokinin containing fractions. The results suggest that dopamine is co-stored with cholecystokinin in large dense vesicles in rat striatum.

Ultrastructural localisation of carnitine acetyltransferase activity in mitochondria of rat myocardium

The acetyl CoA/CoA ratio is an important regulating factor of beta-oxidation in mitochondria and hence of energy production in the myocardium. Carnitine acetyltransferase provides one of the control mechanisms for this ratio during changing energy demand in the heart muscle, possibly by buffering the CoA and carnitine concentration for sustained beta-oxidation. In search for a possible correlation between the activity of this enzyme and ultrastructural changes in heart mitochondria, carnitine acetyltransferase was cytochemically localised in rat myocardium, brought into different metabolic states. In this work we confirm previous observations, namely the formation of contact sites between inner and outer mitochondrial membranes upon catecholaminergic stimulation of the myocardium. It is further shown that this contact site formation might be a prerequisite for carnitine acetyltransferase to demonstrate enzymatic activity and hence control of beta-oxidation in myocardial mitochondria.

Study of intracellular deposition of the anti-leprosy drug clofazimine in mouse spleen using laser microprobe mass analysis

Laser microprobe mass analysis (LAMMA) was used to study the composition of the brick-red crystalline material which had accumulated in the spleen of mice that had received the anti-leprosy drug Clofazimine in their diet for several months. The crystalline deposits light-microscopically resembled pure Clofazimine crystals. The presence of the drug in the crystals was indicated by LAMMA by the appearance of the chloride mass peaks in the negative mass spectra. More specific information was obtained from the positive mass spectra. A mass signal for the protonated molecule was present.

Increased extracellular calcium concentrations in the isolated rat heart: effects on mitochondrial contact site formation

In our previous study, mitochondrial creatine kinase (Mi-CK) activity is localised cytochemically in heart tissue. The activity was found to be exclusively localised in mitochondrial contact sites and the surface density of Mi-CK was increased upon myocardial stimulation (Biermans et al., 1989). As calcium is involved as an intracellular messenger of stimulation, we compared hearts noradrenaline-stimulated in vivo with isolated hearts perfused with buffers containing different calcium concentrations on the surface density Mi-CK.

X-ray micro-analysis of aluminium in pumpkinseed gills

Energy dispersive X-ray micro-analysis was applied to study the (sub-) cellular distribution of aluminium at the gill level of "acid-resistant pumpkinseeds (Lepomis gibbosus) exposed to acidified water (pH = 4.2) and an elevated level of aluminium (1.4 mg Al/l, exposure period = 21 days). Electron dense deposits, located in invaginations as well as inside the gill tissue, were shown to contain elevated levels of aluminium and phosphorus. The micro-analytical findings suggest that the pumpkinseed possesses a defence mechanism, in which the intracellular accumulation of aluminium is limited to restricted sites and to storage in macrophages.

Erythema chronicum migrans: an electron-microscopic study

Spirochaetal organisms are found in skin specimens obtained by biopsy from a erythema chronicum migrans lesion. The histological picture shows a logical localization of a lymphohistiocytic cell infiltrate: deep dermal in the central papule and superficial in the erythematous border. The electron-microscopic characteristics of the micro-organisms in these specimens (regular waving appearance with coils every 0.8-1.2 microns, oblique striation of periplasmatic fibrils, cross-section of 0.3 micron, membranes) correspond to the spiral-like structure of Borreliae isolated from blood. The Borreliae seem to move freely through the matrix of the dermis and are not phagocytized. This brings on the typical clinical picture of the centrifugally spreading erythematous band.

Laser microprobe mass analysis (LAMMA) of aluminum and lead in fine roots and their ectomycorrhizal mantles of Norway spruce (Picea abies (L.) Karst.)

Fine roots and ectomycorrhizal root tips were sampled in a Norway spruce (Picea abies (L.) Karst.) stand in the eastern part of the Belgian Ardennes. The cellular and partly subcellular localizations of aluminum and lead were identified by the micro-analytical laser microprobe mass analysis (LAMMA) technique. In fine roots with secondary structure, localization of aluminum was limited to the peripheral cell layers. Lead was found in the outer layers, and also in the primary phloem. Aluminum penetrated the mycorrhizal mantle, but lead was seldom detected in ectomycorrhizae.

Dehiscence of the facial canal: developmental aspects

In a series of human fetuses, the course of the facial canal in the temporal bone was investigated by the use of light and scanning electron microscopy. The normal development of the facial canal was correlated to clinical aspects of facial nerve dehiscences. Our observations demonstrate a more complex way of facial canal development not limited to the 'simple' ossification of the otic capsule. Endochondral ossification of the otic capsule does not virtually change the shape of the primitive facial sulcus. The fibrous layers surrounding the facial nerve seem to be responsible for the final architecture of the facial canal and not the otic capsule ossification by itself. The time sequence of their histological development is equally important and permitted us to distinguish three phases in facial canal development. The role of disturbances in epigenetic control for the initiation of dehiscences is discussed.

Contact site between inner and outer mitochondrial membrane: a dynamic microcompartment for creatine kinase activity

Creatine kinase is involved in the integration of high-energy metabolism in various tissues. In this study the tissue-specific distribution of the mitochondrial isoform was investigated, both by electrophoresis of rat tissue extracts, and by ultrastructural localisation of creatine kinase activity. Furthermore, the influence of uncoupling of oxidative phosphorylation on mitochondrial creatine kinase activity associated with intermembrane contacts was investigated by enzyme cytochemistry and morphometric analysis. The results of the cytochemical survey indicate that contact sites are a prerequisite for creatine kinase to demonstrate enzymatic activity. Moreover, the extent of creatine kinase active membrane contacts depends on the metabolic state of the mitochondrion, as shown for heart mitochondria in vivo and in vitro, before and after treatment with dinitrophenol.

Early bone formation in the human fetal otic capsule. A methodological approach

The present study was concentrated on the use of energy-dispersive X-ray analysis and backscattered electron imaging as practical tools for advanced autopsy of human fetuses when diagnostic evaluation of ear pathology is required. These methods were used to revisit the primary calcification front of the fetal otic capsule between 18 and 36 weeks' gestational age. Energy-dispersive X-ray analysis indicates an equal Ca/P ratio in all the three layers of the otic capsule. These results are discussed in view of calcium homeostasis and inner ear function.

Early ossification within the human fetal otic capsule: morphological and microanalytical findings

Besides the use of conventional techniques such as light and polarization microscopy, the present paper proposes the combined use of transmission electron microscopy, secondary and backscattered electron imaging, energy dispersive X-ray analysis and computed tomography for the diagnostic evaluation of ear pathology in the human fetus. These methods were used to revisit the primary calcification front of the fetal otic capsule between 16 and 23 weeks gestational age. Ultramicroscopic evaluation demonstrates similar fetal bone formation to that found in other bones of the human fetus. The formation of the endosteal and periosteal layers is a typical example of early intra-membranous ossification. The enchondral layer is made up of fibrillar bone, laid down around the calcified cartilage remnants. Microchemical analysis indicates a significantly higher Ca/P ratio in the endochondral layer with respect to the endosteum and periosteum. The consequences of a lower Ca/P ratio in the endosteal layer are discussed in view of calcium homeostasis and inner ear function.

Ultrastructural localisation of creatine kinase activity in the contact sites between inner and outer mitochondrial membranes of rat myocardium

The mitochondrial isoenzyme of creatine kinase, together with the ADP/ATP translocase, most probably belongs to a functional multi-enzyme complex located on the inner mitochondrial membrane. The outer membrane is a necessary constituent of this microcompartment. On the other hand, electron microscopic visualisation demonstrated the formation of contact sites between inner and outer mitochondrial membranes as a reaction to variations of the energy metabolism. In search for a possible correlation between these biochemical and morphological phenomena, rat myocardia were brought into the required energy state by stimulation through catecholaminergic mechanisms or adjusted perfusion with amytal. Subsequently, creatine kinase was cytochemically localised. Creatine kinase activity is demonstrated in membrane contacts between inner and outer mitochondrial membranes. The extent of contact sites and creatine kinase activity depends on the metabolic state as shown by morphometric analysis of the surface density of cytochemical reaction product. This surface density diminishes drastically after inhibiting the metabolic activity with amytal. It is concluded that these contact sites are dynamic micro-environments in which the active site of creatine kinase, oxidative phosphorylation and ADP/ATP transport interact during basal and stimulated metabolism.