Effects of aqua-treadmill exercise on selected blood parameters and on heart-rate variability of horses

The objectives of the present study were to investigate the effects of Aquatraining of horses (aqua-treadmill exercise; treadmill manufactured by Equitech - L.u.S. Equipment, Warendorf, Germany) on selected blood parameters [lactic acid concentration (mmol/l), haemoglobin content (g/l)] and on heart-rate variability (HRV) [heart rate (beats per min; b.p.m.), standard deviation of all NN-intervals (SDNN; ms), normalized power of the low and high frequency band (LFnorm, Hfnorm; au), % recurrence, % determinism and ratio(corr)]. Seven horses performed six exercise tests with different work loads (walking (x = 1.56 +/- 0.08 m/s) and trotting (x = 2.9 +/- 0.13 m/s): dry, water above the carpus and water above the elbow). The standardized test-protocol was: 5 min warm-up at walk while the water was pumped in, followed by the 20-min exercise period at walk or trot, followed by a 5-min walk while pumping out the water. Blood samples were taken prior to each test at rest in the stable, as well as exactly 5 min after the end of the 20-min exercise period. Electrocardiograms were recorded during rest and the 20-min exercise period. Compared to rest, neither the chosen velocities, the two water levels, nor the dry tests led to a significant increase of the lactic acid concentration in any horse. The haemoglobin content showed a significant increase as a result of exercise. Significant differences could be found between the heart rates at rest and the six exercise tests and between the mean of the levels 'walking' and the mean of the levels 'trotting'. An exercise-induced change of HRV was characterized by a decreasing SDNN, a significantly higher LFnorm (sympathetic influence) combined with a significantly lower HF(norm) power (parasympathetic activity) and a rising degree of order (significantly higher % determinism and nearly unchanged % recurrence) and stability (significantly rising ratio(corr)) of the recurrence plot. In conclusion, the used training-protocol for aqua-treadmill exercises only represents a medium-sized aerobic work load for horses, but the different levels of burden were indicated especially by changes in HRV.

Thyroxine and illness severity in very low-birth-weight infants

The objective of this study was to determine the relationship between thyroxine (T4) and illness severity in a population of preterm infants. We investigated a cohort of infants with birth weights 1,500 g or less from a single level III neonatal intensive care unit who received a minimum of one cranial sonogram to screen for intraventricular hemorrhage (IVH) and one newborn screen for T4 during a 2-year period, (n = 284). The Score for Neonatal Acute Physiology (SNAP) was used to measure illness severity. T4 and SNAP were investigated in relationship to mortality, IVH, and severe IVH. T4 correlated inversely with SNAP (R = -0.46, p < 0.01). Infants with severe IVH and mortality had lower T4 and higher SNAP scores when compared to infants without these conditions. These differences persisted after controlling for the confounding effect of gestational age. Analysis of receiver operator curves indicated that high SNAP and low T4 were equivalently associated with IVH, severe IVH, and mortality. Our data indicate that T4 is associated with illness severity in very low-birth-weight infants. Low T4 levels and high SNAP scores are both associated with the outcomes of IVH and mortality in very low-birth-weight infants.

[Isolated left ventricular papillary muscle rupture: a rare event after blunt thoracic trauma]

We report about a 20-year old man, who suffered from a car accident under the influence of ecstasy. Although he had no visible injuries at the chest, the accident caused an isolated rupture of a papillary muscle of the mitral valve. A review of the literature shows the rarity of this kind of injury. The mechanisms of traumatic papillary muscle rupture, the diagnosis, therapy and complications are discussed.

[Dynamic cardiomyoplasty: evaluation of an alternative procedure in the treatment of terminal heart failure]

Dynamic cardiomyoplasty (DCMP) was developed as an alternative treatment for patients with end-stage heart failure. The first clinical application of this technique was in 1985 by Carpentier und Chachques. Since then, DCMP has been performed in more than 1000 patients world-wide. During the initial experience with DCMP, survival for NYHA class IV patients was clearly shown to be much worse than that for class III patients. By careful patient selection, operative mortality has decrease from 31% in the past to less than 5% today. The vast majority of patients have demonstrated significant improvement in NYHA class and overall quality of life with only minor effects on systolic cardiac function. Clinical work, as well as recent animal work supports the hypothesis that by a combination of long-term elastic constraint and active dynamic assist, DCMP decreases myocardial wall stress. This process results in a "reverse remodeling" of the insufficient heart with an improvement of the "contractility reserve". To prove the effectiveness of DCMP versus medical therapy alone, the C-SMART study started in 1994, as the first and only randomized trial. Unfortunately the study was stopped in 1998 due to slow patient recruitment after enrolling 103 patients. The study showed that, from a symptoms standpoint, patients with DCMP were improved over those who were medically treated. However, there was no significant difference for survival between the two groups after 12 months. The lack of a clear survival advantage and the relatively poor and inconsistent hemodynamic benefit of DCMP have hindered its acceptance to date as a treatment alternative for patients with end-stage heart failure. The ultimate role of DCMP in the treatment of heart failure will depend on the outcome of future developments to improve the contractility and the long-term durability.

Dynamic cardiomyoplasty in a growing organism

BACKGROUND

Until now cardiomyoplasty has been a treatment option for adults only. However, there may be a demand for cardiomyoplasty in children. The purpose of this study was to investigate the possibility of applying the method of cardiomyoplasty before growth is completed.

METHODS

The latissimus dorsi muscle (LD) was wrapped around the heart of 20 Göttinger Minipigs (9.1 +/- 1.2 kg body weight). The LD was fixed to the pericardium in group 1 (n = 11) and to the epimyocardium in group 2 (n = 9) and stimulated with burst impulses. After 5.6 +/- 1.8 months hemodynamic and histologic follow-up-examinations were carried out in 13 surviving animals (weight 32.4 +/- 5.3 kg).

RESULTS

In group 1 (n = 6) only the left ventricle was covered by the LD. In 4 animals the LD contracted strongly; in 2, the outer border of the muscle was atrophied. In group 2 (n = 7) both ventricles were covered by the LD in all animals and showed strong contractions. In 2 animals the outer border of the muscle was atrophied. In both groups the contracting parts of the LD showed an intact muscle structure, but compared with the contralateral LD, there was a higher percentage of interstitial fat and connective tissue. Hemodynamic measurements and the well-being of the animals suggest that restriction of cardiac chamber diameter did not occur. The electrical stimulation of the LD caused a minimal increase of left ventricular pressure and aortic peak flow in group 2.

CONCLUSIONS

Cardiomyoplasty can be applied in a growing organism. There is growth of the LD with the heart. The muscle structure remains intact. To prevent dislocation of the LD, it seems to be important to fix the LD directly onto the epimyocardium.

Scanning electron microscopical investigations of broncho-alveolar casts after intratracheal asbestos fibre instillation

The evaluation of the toxicity of mineral fibres has been tried to achieve in experimental animal models. However, the appearance of fibres in the pleural space could not be explained satisfactorily. Histomorphological examinations showed that intratracheal instillation of asbestos fibres leads to parabronchial and intraalveolar granulomatous tissue reactions and bronchial epithelial regenerations. For further elucidation of the pathogenesis of lung cancer and of mesothelioma the localisation and transport of inhaled fibres is of high interest. Thus, a three dimensional visualization of the structure of rat lungs before and after intratracheal instillation of UICC crocidolite fibres was performed by plastic casts to follow the way of asbestos fibres in the lung tissues and the pleura. The casts allowed to demonstrate airway structures with imprints of epithelial cells and blood vessels of normal and treated animals by scanning electron microscopy. Instilled asbestos fibres transformed bronchial structures and resulted in cystic deformations of the pleural surface. The penetration of single fibres through bronchial trunks and the visceral pleura could be shown for the first time in a three-dimensional topography of the affected tissue. Now, there is support for similar results of histomorphological examinations indicating the possibility that asbestos fibres could penetrate the pleura and migrate into the pleural space. The question if the migration of fibres is a mechanical movement or an active transport is still under discussion.

Expression of TNFalpha and TGFbeta1 in Guillain-Barré syndrome: correlation of a low TNFalpha-/TGFbeta1-mRNA ratio with good recovery and signs for immunoregulation within the cerebrospinal fluid compartment

In the pathogenesis of Guillain-Barré syndrome (GBS) a dysregulation of cytokines is supposed. The protein concentration and mRNA expression of TNFalpha and TGFbeta1 were investigated in cerebrospinal fluid (CSF) and blood in 10 patients with GBS. TNFalpha-mRNA was increased at the beginning of the disease and demonstrated a decline during the time course (P = 0.001). The level of TNFalpha protein was elevated in only a few patients. TGFbeta1-mRNA (P = 0.001) and the active TGFbeta1 protein (P < 0.05) increased during the course of GBS, and the level of total TGFbeta1 protein was temporarily elevated (P = 0.005). A low ratio of TNFalpha-/TGFbeta-mRNA expression correlated to a good clinical course (P < 0.05). The results indicate an association of TNFalpha with disease activity. TGFbeta1 seems to terminate and limit the inflammatory reactions and to promote the healing course of GBS. In addition the investigations show that in GBS immunoregulatory mechanisms also take place in the CSF compartment itself and that CSF cells are involved in the production of pro-inflammatory as well as immunosuppressive cytokines.

Piccolo, a presynaptic zinc finger protein structurally related to bassoon

Piccolo is a novel component of the presynaptic cytoskeletal matrix (PCM) assembled at the active zone of neurotransmitter release. Analysis of its primary structure reveals that Piccolo is a multidomain zinc finger protein structurally related to Bassoon, another PCM protein. Both proteins were found to be shared components of glutamatergic and GABAergic CNS synapses but not of the cholinergic neuromuscular junction. The Piccolo zinc fingers were found to interact with the dual prenylated rab3A and VAMP2/Synaptobrevin II receptor PRA1. We show that PRA1 is a synaptic vesicle-associated protein that is colocalized with Piccolo in nerve terminals of hippocampal primary neurons. These data suggest that Piccolo plays a role in the trafficking of synaptic vesicles (SVs) at the active zone.

Minimally invasive saphenous vein harvesting: is there an improvement of the results with the endoscopic approach?

OBJECTIVES

In the postoperative course after conventional open removal of the greater saphenous vein, wound healing disturbances are common and often painful. Therefore the primary goal of this investigation was to prove the safety and practicability of this new less invasive technique for saphenous vein harvesting and the effect on complications and morbidity.

METHODS

The study comprised 103 coronary artery bypass grafting (CABG) patients with an endoscopic approach to harvest the saphenous vein (MIVH). We used the VasoView II system developed by Origin, and compared the intraoperative procedure time and the clinical results with 105 equivalent patients in which a conventional open technique was used.

RESULTS

In 101 patients endoscopic vein harvesting was successful; a conversion into open technique was necessary in two patients. On average 2.6 vein segments could be harvested in the endogroup versus 2.9 segments in the opengroup. The mean procedure time was 13.2 min per segment in the endogroup compared to 12.2 min per segment in the opengroup. Relevant hematoma were found in 29 patients (27.6%) of the opengroup, whereas only nine patients (8.7%) of the endogroup revealed severe hematoma. Infection was apparent in nine patients (8.5%) after conventional vein harvesting. Two infections were found after endoscopic intervention.

CONCLUSIONS

Endoscopic saphenous vein harvesting as part of a less invasive concept in cardiac surgery is a safe and after the learning curve, fast alternative to harvest the saphenous graft. The cosmetic result is excellent and the complication rate seems to be lower. It must be noted however, that the cost effectiveness of the method has to be proved and that further histological and functional studies are needed in order to check the intimal structure of the vein.

Immunomodulatory effects of IFNbeta-1b on the mRNA-expression of TGFbeta-1 and TNFalpha in vitro

The mechanisms by which IFNbeta-1b acts in the treatment of multiple sclerosis (MS) patients are not completely known. We investigated the influence of IFNbeta-1b on the mRNA-expression of the immunosuppressive cytokine TGFbeta-1 and the proinflammatory mediator TNFalpha in an in vitro model by the method of non-radioactive in situ hybridization. Peripheral blood lymphocytes (PBL) were isolated from eight patients with relapsing remitting form of MS during remission and from six healthy controls. They were stimulated with IFNbeta-1b in different concentrations for 24 h. In both groups a statistically significant dose-dependent increase of TGFbeta-1-mRNA and decrease of TNFalpha-mRNA was demonstrable in the cultured stimulated blood lymphocytes compared to unstimulated cells. Stimulations with lipopolysaccharide (LPS) led to an increase of both cytokine-mRNAs in the lymphocytes. These data suggest specific and dose-dependent effects of IFNbeta-1b and hint at immunomodulatory properties of this drug to regulate the cytokine dysbalance in MS. This might be one mechanism by which IFNbeta-1b mediates its beneficial effects on the course of the disease.

Hepatocyte growth factor/scatter factor and its receptor c-Met are overexpressed and associated with an increased microvessel density in malignant pleural mesothelioma

Hepatocyte growth factor/scatter factor (HGF/SF) stimulates cell proliferation, motility and invasiveness via its receptor c-Met during embryogenesis and repair processes. It induces angiogenesis, promoting endothelial cell migration and capillary-tube formation in vivo. Co-expression of HGF/SF and c-Met receptor results in enhanced tumour growth, invasiveness and a mesenchymal-epithelial transition in some experimental tumours. Since mesothelioma cells have been reported to express c-Met receptor and to migrate in response to HGF/SF, we investigated human malignant pleural mesotheliomas for the demonstration of possible co-expression of the growth factor and its receptor. The microvessel density of the tumours was also analysed in order to assess the influence of HGF/SF expression on tumour angiogenesis. Thirty-nine paraffin-embedded specimens of malignant pleural mesotheliomas were immunostained by anti-HGF/SF and anti-c-Met antibodies and semiquantitatively evaluated. c-Met mRNA expression was visualised in ten tumour samples by a fluorescent in situ hybridisation method. Microvessel density was calculated by counting microvessels with a high-power field (200x) on von-Willebrand-factor-stained slides. We found an increased production of HGF/SF in 33/39 tumours and a corresponding overexpression of c-Met receptor in 29/39 specimens. The FISH method detected increased transcription of c-Met mRNA in malignant cells and in neighbouring vascular endothelial cells. HGF/SF-positive mesotheliomas had significantly higher microvessel densities compared to their HGF/SF-negative counterparts. The observed co-expression of HGF/SF and c-Met in malignant pleural mesotheliomas suggests a possible self-stimulation (autocrine loop) of tumour cells. On the basis of the significantly higher microvessel density values of malignant mesotheliomas overexpressing HGF/SF, we postulate, that HGF/SF may be an additional relevant factor in tumour angiogenesis in malignant pleural mesotheliomas.

Supernatants from quartz dust treated human macrophages stimulate cell proliferation of different human lung cells as well as collagen-synthesis of human diploid lung fibroblasts in vitro

Silicosis is a chronic lung disease, which is caused by inhalation of silica-containing dusts, leading to pulmonary fibrosis. Alveolar macrophages play a key-role in defence against these particles entering the lung. As a result of phagocytosis, the macrophages release mediators, which are involved in various processes of inflammation and immunological defence mechanisms. We established an in-vitro test system composed of human macrophages, human pneumocyte type II cells (line A-549), human diploid lung fibroblasts (line Wi38) and human tracheobronchial epithelial cells (line BEAS-2B). With this model, we were able to study the influence of various cytokines, produced by the macrophages, on cell proliferation and collagen synthesis (only fibroblasts) of the cells in our test-system. In this report, we will summarize data obtained from our in-vitro test system on two cytokines, which are thought to be important in pathogenesis of lung fibrosis: insulin-like growth factor-1 (IGF-1) and transforming growth factor-beta (TGF-beta).

Induction of manganese superoxide dismutase gene expression in bronchoepithelial cells after rockwool exposure

Superoxide dismutases play an important protective role in the lung defense against the pro-oxidative effect of fibrous dusts (e.g. crocidolite fibers). Particularly crocidolite, but also other asbestos fibers, are known to induce cellular antioxidant defense. Although rockwool, a man-made fiber made from rock, is used widely for insulation purposes, its effects on the superoxide dismutases in bronchoepithelial cells have not been investigated. Thus, the purpose of this study was to determine whether human bronchoepithelial cells (BEAS 2B) respond to rockwool fibers (115-4 experimental rockwool fiber) by induction of MnSOD mRNA and an increase of MnSOD activity levels. The results were compared with BEAS 2B cells exposed to silica (alpha-quartz: DQ12; SiO2) and UICC (Union Internationale Contre le Cancer) crocidolite (concentrations of all dusts: 0, 2, 5, 10, 25, 50 micrograms/cm2 = 0, 2.4, 6, 12, 30, 60 micrograms/ml; 24-h exposure) as control fibers. Scanning electron microscopy confirmed close dust cell contact under all experimental settings. Very low MnSOD mRNA baseline levels rose significantly (p < 0.001) in BEAS 2B cells exposed to all three dusts at 2 micrograms/cm2. However, at > 25 micrograms/cm2 MnSOD mRNA levels in silica- and crocidolite- but not in rockwool-exposed cells decreased. Slight (no significance) increases of MnSOD activity were observed which decreased at higher dust (> 5 micrograms/cm2) concentrations. These results suggest that: (1) like crocidolite and silica, rockwool accelerates MnSOD gene expression in bronchoepithelial cells; (2) an increase of MnSOD mRNA levels is not accompanied by MnSOD activity elevation; (3) in contrast to rockwool, high concentrations (> or = 25 micrograms/cm2) of crocidolite and silica reduced MnSOD activity and MnSOD mRNA levels. Because oxidants (H2O2) and crocidolite fibers were shown to reduce SOD activity, lack of active MnSOD protein may be caused by inactivation on a post-translational level. Furthermore, the decline of MnSOD mRNA and MnSOD activity levels coincides with increasing cytotoxicity. In conclusion, rockwool was demonstrated to induce MnSOD gene expression, perhaps because of its pro-oxidative effect in bronchoepithelial cells. In contrast to crocidolite and silica, rockwool fibers are not cytotoxic in this experimental setting.

Expression of type IV collagenase correlates with the expression of vascular endothelial growth factor in primary non-small cell lung cancer

Tumor growth and metastasis are angiogenesis-dependent processes initiated and regulated by a number of cytokines. Vascular endothelial growth factor (VEGF) is a potent angiogenic protein with a selective mitogenic effect on vascular endothelial cells, known to be involved in physiological (embryogenesis) and pathophysiological (rheumatoid arthritis, tumor) angiogenesis. An increased expression of matrix metalloproteinase type IV collagenase has been reported in invading endothelial cells in vitro and in malignant cells, degrading structures of the basement membranes in various human malignancies. In the present study we investigated the expression of the genes for type IV collagenase and vascular endothelial growth factor (VEGF) in 40 cases of primary non-small-cell lung cancer (NSCLC). Specimens were immunostained by an antibody directed against VEGF and mRNA transcripts of VEGF and type IV collagenase were localized by non-radioactive in situ hybridization. VEGF mRNA was detected in 33 neoplasms, while in 23 cases transcripts of the type IV collagenase gene were visualized by digoxigenin-labeled cDNA probes. Transcripts of both mRNAs were detected in malignant cells. Furthermore, anti-VEGF immunostaining was present in newly formed microvessels close to the atypical cells, and mRNA of type IV collagenase was present in stromal cells adjacent to the tumor. A statistically significant correlation was found between the expression of type IV collagenase and VEGF (P = 0.0061). These data suggest a double role for type IV collagenase in the metastatic process of NSCLC: (1) facilitating the invasion of tumor cells by the proteolytic cleavage of the basement membrane and (2) similarly supporting the endothelial cell invasion essential for tumor angiogenesis. Furthermore, our findings sustain the hypothesis that metastatic spread and angiogenesis are associated with a clonal expansion of highly angiogenic and invasive tumor cell clones.

Corticosteroids induce expression of transforming-growth-factor-beta1 mRNA in peripheral blood mononuclear cells of patients with multiple sclerosis

The mechanisms by which corticosteroids act in the treatment of an acute relapse in multiple sclerosis (MS) are not completely known. We investigated the mRNA and protein expression of transforming-growth-factor-beta1 (TGFbeta1), a cytokine with anti-inflammatory and immunosuppressive potentials, in peripheral blood mononuclear cells (PBMC) and serum of 10 patients with an acute relapse of MS before, during and after the treatment with 500 mg prednisolone daily over 5 days. The expression of TGFbeta1-mRNA increased at day 3-5 and declined at day 8-10. Serum levels of TGFbeta1 demonstrated a comparable course. The present data suggest that corticosteroids induce the expression of TGFbeta1 in vivo. This is might be an other mechanism by which corticosteroids mediate immunosuppression.

Expression of c-Met receptor and hepatocyte growth factor/scatter factor in synovial sarcoma and epithelioid sarcoma

Overexpression of c-Met receptor/hepatocyte growth factor (scatter factor) system (c-Met/HGF/SF) as a physiologically paracrine cellular signaling system is thought to be involved in the progression of malignant tumours. In 26 synovial sarcomas and epithelioid sarcomas, c-Met and HGF/SF expression was analysed immunohistochemically. There were 10 biphasic synovial sarcomas, 7 of which showed moderate to strong c-Met expression in epithelial areas compared with the fibrous component, with corresponding expression of HGF/SF. Six of 9 monophasic fibrous synovial sarcomas showed only very faint c-Met and corresponding HGF/SF expression. In 7 epithelioid sarcomas strong expression of c-Met and HGF/SF was observed within epithelioid tumour cells. Non-radioactive in situ hybridization demonstrated the synthesis of c-Met receptor in tumor cells by detecting c-met-mRNA. This analysis shows that in synovial sarcomas and epithelioid sarcomas, tumour entities with epithelial and mesenchymal structures, c-Met and HGF/SF overexpression can be detected, indicating a role of this signaling system in these subtypes of sarcoma, and especially in the more epithelioid tumour phenotype. An autocrine interaction between overexpressed c-Met receptor and HGF/SF may be hypothesized.

Survival benefit of hyperthermia in a prospective randomized trial of brachytherapy boost +/- hyperthermia for glioblastoma multiforme

PURPOSE

To determine if adjuvant interstitial hyperthermia (HT) significantly improves survival of patients with glioblastoma undergoing brachytherapy boost after conventional radiotherapy.

METHODS AND MATERIALS

Adults with newly-diagnosed, focal, supratentorial glioblastoma < or = 5 cm in diameter were registered postoperatively on a Phase II/III randomized trial and treated with partial brain radiotherapy to 59.4 Gy with oral hydroxyurea. Those patients whose tumor was still implantable after teletherapy were randomized to brachytherapy boost (60 Gy at 0.40-0.60 Gy/h) +/- HT for 30 min immediately before and after brachytherapy. Time to progression (TTP) and survival from date of diagnosis were estimated using the Kaplan-Meier method.

RESULTS

From 1990 to 1995, 112 eligible patients were entered in the trial. Patient ages ranged from 21-78 years (median, 54 years) and KPS ranged from 70-100 (median, 90). Most commonly due to tumor progression or patient refusal, 33 patients were never randomized. Of the patients, 39 were randomized to brachytherapy ("no heat") and 40 to brachytherapy + HT ("heat"). By intent to treat, TTP and survival were significantly longer for "heat" than "no heat" (p = 0.04 and p = 0.04). For the 33 "no heat" patients and 35 "heat" patients who underwent brachytherapy boost, TTP and survival were significantly longer for "heat" than "no heat" (p = 0.045 and p = 0.02, respectively; median survival 85 weeks vs. 76 weeks; 2-year survival 31% vs. 15%). A multivariate analysis for these 68 patients adjusting for age and KPS showed that improved survival was significantly associated with randomization to "heat" (p = 0.008; hazard ratio 0.51). There were no Grade 5 toxicities, 2 Grade 4 toxicities (1 on each arm), and 7 Grade 3 toxicities (1 on "no heat" and 6 on the "heat" arm).

CONCLUSION

Adjuvant interstitial brain HT, given before and after brachytherapy boost, after conventional radiotherapy significantly improves survival of patients with focal glioblastoma, with acceptable toxicity.

Expression and localization of vascular endothelial growth factor and its receptor flt in pulmonary sarcoidosis

Vascular endothelial growth factor (VEGF) is a multifunctional cytokine, which has recently been reported to enhance the activation and migration of monocytes through the flt receptor in vitro, which are key events in granuloma formation of granulomatous disorders and in sarcoidosis. Since activated macrophages and monocytes are known to be involved in sarcoid granuloma formation in sarcoidosis, we investigated the expression of VEGF and its receptor flt in 33 paraffin-embedded lung tissue biopsies of patients with pulmonary sarcoidosis. VEGF-mRNA was localized by nonradioactive in situ hybridization, VEGF and flt expression were visualized immunohistochemically. We found an increased transcription and protein production of VEGF and an overexpression of flt in activated alveolar macrophages, in epitheloid cells, and in multinuclear giant cells of pulmonary sarcoid granulomas.

A method to improve the latency estimation of the frequency-following potential (FFP)

If the latency of a noisy frequency-following potential (FFP) is estimated by determining the shift of the (periodical) cross-correlation function (CCF) between the stimulus and the FFP, the result may be unambiguous only within +/-1 or +/-2 periods of the CCF, because the absolute maximum and adjacent local maxima may not be significantly different. Here we present a method to amplify this difference by applying amplitude modulated stimuli. Using this method we first illustrate the effect of the method by a simulation and then demonstrate its usefulness by measuring real FFPs and estimating their latencies.

Simultaneous restitution of matrix and cells in gastric ulcer: use of a combined in-situ hybridization and immunohistochemistry technique applicable to paraffin-embedded tissue

The restoration of gastric tissue after ulceration involves cellular and matrix components. Our aim was to investigate the kinetics of collagen expression and cellular proliferation in an animal model of gastric ulcer. To demonstrate the expression of type I and IV collagen mRNAs by proliferating cells, a method combining in-situ hybridization and immunohistochemistry was devised. In order to avoid the disadvantages of radioisotopes, digoxigenin-labeled RNA-riboprobes were utilized and combined with single-step immunohistochemistry. This method proved sensitive enough to detect type I and IV procollagen mRNA transcripts in the submucosal area beneath the ulcer crater or adjacent to the ulcer rim. In addition, a subset of cells transcribing either procollagen type I or IV RNA was concomitantly positive for proliferating cell nuclear antigen by immunohistochemistry. Focal proliferation of cells simultaneously expressing extracellular matrix components may therefore occur in the gastric submucosa after ulceration, starting as soon as 3 days after the insult and continuing for several weeks. The devised method of combined in-situ hybridization and immunohistochemistry can be used with standard paraffin-embedded tissues, yields results within 2 days, and avoids radioisotopes.