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PubMed1995

Infrared video imaging of subsurface vessels: a feasibility study for the endoscopic management of gastrointestinal bleeding.

The feasibility of infrared video imaging of subsurface vessels in the stomach was investigated both experimentally and in more detail using computer simulations of light propagation. Infrared video imaging was first attempted in several experimental situations. Images of a human arm illuminated with infrared light (wavelength > 700 nm) revealed subcutaneous venous structures not revealed by visible light (wavelength of 500 to 600 nm). An infrared-sensitive video endoscope was used to view both a human arm and normal stomach wall. Infrared illumination within the stomach enhanced only the larger subsurface vessels. Infrared transillumination of a rat skin flap window chamber allowed video recording of images during injection of an absorbing dye, indocyanine green, into the blood volume and showed that indocyanine green can enhance the contrast in infrared images of small vessels. Computer simulations of vessels of varying depths and sizes indicated successful detection was possible by infrared imaging. Computer simulations demonstrated that the shadow caused by an imaged subsurface vessel has two characteristics: (1) the central loss of reflectance, which indicates the size of the vessel, and (2) the full-width half-maximum of the reflectance loss, which indicates the depth of the vessel. The simulations further suggested that images of small vessels can be dramatically enhanced (68-fold) by indocyanine green, which attenuates the transmittance of scattered light from behind the vessels to the surface for observation. On the other hand, indocyanine green enhances the contrast of large vessels to a lesser degree (2.6-fold). The ultimate goal is to develop an endoscopic video imaging system capable of capturing reflected light from the stomach wall.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Myocardial wall motion evaluation using amplitude frequency spectral analysis.

Frequency spectral analysis of cardiac wall motion as calculated from the recorded video kymogram are demonstrated. Characteristic harmonics following the fundamental frequency of the cardiac rate have been demonstrated to have an alternating sequential energy distribution as measured from the free margin of the left ventricle of humans. The characteristic patterns occur in approximately 80% of the 50 patients evaluated. The correlation of these harmonics with physiologic events is not yet complete. Amplitude frequency spectral analysis offers an objective method for analysis of cardiac kymography not otherwise possible.

Adult↗

PubMed2005

Cyclical interactions between two outer doublet microtubules in split flagellar axonemes.

The beating of cilia and flagella is based on the localized sliding between adjacent outer doublet microtubules; however, the mechanism that produces oscillatory bending is unclear. To elucidate this mechanism, we examined the behavior of frayed axonemes of Chlamydomonas by using high-speed video recording. A pair of doublet microtubules frequently displayed association and dissociation cycles in the presence of ATP. In many instances, the dissociation of two microtubules was not accompanied by noticeable bending, suggesting that the dynein-microtubule interaction is not necessarily regulated by the microtubule curvature. On rare occasions, association and dissociation occurred simultaneously in the same interacting pair, resulting in a tip-directed movement of a stretch of gap between the pair. Based on these observations, we propose a model for cyclical bend propagation in the axoneme.

Adenosine Triphosphate↗

PubMed1996

[Official approach to sexual abuse].

The topic of sexual abuse must be seen from different points of view as the State presents itself at three levels: legislative executive, and judicial. The executive power is mainly represented by the Jugendamt (Youth Office) whose tasks are set out precisely in the Kinder- und Jugendhilfegesetz (KJHG) (Child Protection Act); however, the Act itself does not state clearly how the responsibilities should be fulfilled. Even so, cooperation between non-government organizations, the Family Court and other cited institutions (i.e. school, police) is necessary. In addition, the staff members of the Youth Office should be experts (i.e. adequate education, advanced training, supervision) but often lack the necessary knowledge of law, developmental psychology and paediatric psychiatry. The necessary skills such as interviewing methods, class- and age-specific language and professional recording are not always available and the plans for the child's care prescibed by the Act are often inadequate. The data-protection regulations play a counterproductive role and financial shortages are often born by the weakest members of the society. The judicial power in the Family Court area has to free itself from possible procedures of the Criminal Court and has to intervene earlier. A legal representation of the child should be made available as soon as possible. The family judges should exhaust all legal possibilities. Police and public prosecution should cooperate better with Youth Protection and Family Courts. Judges should be more willing to believe child-witnesses. All the possibilities of the Code of Criminal Procedure should be used in favour of the child. The compensation for victims of sexual abuse should be more directly aimed towards helping the victims. The legislative power could break up a narrow jurisdiction (continuation of offence, definition of violence, verification of credibility). It could apply new methods (video-recording to replace public examination, psychotherapeutic treatment instead of, or combined with penal sentence sanctions) and correct inadequate acts (competence of Family Court and Guardianship Court, counterproductive data protection). In conclusion, it must be said that many details concerning the official approach to sexual abuse could be improved. However, the main problem lies in the fact that the State does not really attempt to create a systematic solution to sexual abuse. The ad hoc reaction in Germany has led to an uncoordinated set of rules and practices without a common sense of purpose.

Adolescent↗

PubMedDate not supplied

A comparison of two computer-automated semen analysis instruments for the evaluation of sperm motion characteristics in the stallion.

Two commercially available computer-automate semen analysis instruments (CellSoft Automated Semen Analyzer and HTM-2000 Motion Analyzer) were compared for their ability to report similar results based on the analysis of pre-recorded video tapes of extended, motile stallion semen. The determinations of the percentage of motile cells by these instruments were more similar than the comparisons between subjective estimates and either instrument. However, mean values obtained from the same sample may still differ by as much as 30 percentage units between instruments. Instruments varied with regard to the determinations of mean sperm curvilinear velocity and sperm concentration, but mean sperm linearity determinations were similar between the instruments. We concluded that the determinations of sperm motion characteristics by subjective estimation, CellSoft Automated Semen Analyzer, and HTM-2000 Motility Analyzer are often dissimilar, making direct comparisons of results difficult.

Animals↗

PubMed2004

Complex flagellar motions and swimming patterns of the flagellates Paraphysomonas vestita and Pteridomonas danica.

Most flagellates with hispid flagella, that is, flagella with rigid filamentous hairs (mastigonemes), swim in the direction of the flagellar wave propagation with an anterior position of the flagellum. Previous analysis was based on planar wave propagation showing that the mastigonemes pull fluid along the flagellar axis. In the present study, we investigate the flagellar motions and swimming patterns for two flagellates with hispid flagella: Paraphysomonas vestita and Pteridomonas danica. Studies were carried out using normal and high-speed video recording, and particles were added to visualize flow around cells generating feeding currents. When swimming or generating flow, P. vestita was able to pull fluid normal to, and not just along, the flagellum, implying the use of the mastigonemes in an as yet un-described way. When the flagellum made contact with food particles, it changed the flagellar waveform so that the particle was fanned towards the ingestion area, suggesting mechano-sensitivity of the mastigonemes. Pteridomonas danica was capable of more complex swimming than previously described for flagellated protists. This was associated with control of the flagellar beat as well as an ability to bend the plane of the flagellar waveform.

Animals↗

PubMed2001

Tissue-specific neuro-glia interactions determine neurite differentiation in ganglion cells.

Guided formation and extension of axons versus dendrites is considered crucial for structuring the nervous system. In the chick visual system, retinal ganglion cells (RGCs) extend their axons into the tectum opticum, but not into glial somata containing retina layers. We addressed the question whether the different glia of retina and tectum opticum differentially affect axon growth. Glial cells were purified from retina and tectum opticum by complement-mediated cytolysis of non-glial cells. RGCs were purified by enzymatic delayering from flat mounted retina. RGCs were seeded onto retinal versus tectal glia monolayers. Subsequent neuritic differentiation was analysed by immunofluorescence microscopy and scanning electron microscopy. Qualitative and quantitative evaluation revealed that retinal glia somata inhibited axons. Time-lapse video recording indicated that axonal inhibition was based on the collapse of lamellipodia- and filopodia-rich growth cones of axons. In contrast to retinal glia, tectal glia supported axonal extension. Notably, retinal glia were not inhibitory for neurons in general, because in control experiments axon extension of dorsal root ganglia was not hampered. Therefore, the axon inhibition by retinal glia was neuron type-specific. In summary, the data demonstrate that homotopic (retinal) glia somata inhibit axonal outgrowth of RGCs, whereas heterotopic (tectal) glia of the synaptic target area support RGC axon extension. The data underscore the pivotal role of glia in structuring the developing nervous system.

Animals↗

PubMed1988

Growth cone configuration and advance: a time-lapse study using video-enhanced differential interference contrast microscopy.

We have analyzed the dynamics of growth cone configuration using video-enhanced contrast differential interference contrast microscopy. Regenerating neurites from NGF-treated PC12 cells and sympathetic neurons were observed in real time during their elongation and reviewed by time-lapse video recordings. This technique provided a high-resolution view of motile growth cone elements including filopodia, microspikes, lamellipodia and ruffles. On the basis of our observations, a multistage model for growth cone advance is proposed. Elongation commences with lamellipodial spreading. If the newly extended lamellipodium does not retract or lift off the substrate in the form of a ruffle, a second phase--consolidation--occurs, in which the lamellipodium thickens as it fills with cytoplasm and organelles. The consolidated area then undergoes further transformation into an area of neuritic shaft as new lamellipodia form at the leading and peripheral zones of the distal process. We never observed filopodia or microspikes contracting to propel the growth cone forward. We also noted that elongating tips generally had large varicosities within 20 micron of their leading edges. These may play a role in neurite outgrowth and in the formation of smaller, synaptic vesicle-containing varicosities. The dynamic behavior of the growth cone was under the control of NGF. Withdrawal of NGF resulted in the disappearance of motile structures and cessation of growth, while readdition of NGF triggered the rapid reappearance of these structures and the resumption of growth. The high-resolution video microscopy of living growth cones provides necessary baseline information, as well as a bioassay paradigm, for future studies on the molecular mechanisms of nerve growth.

Adrenal Gland Neoplasms↗

PubMed2003

A comparison of the anti-inflammatory activities of conjugated estrogens and 17-beta estradiol.

OBJECTIVE AND DESIGN: Unregulated chronic inflammatory process partly due to an estrogen deficiency may render postmenopausal women vulnerable to degenerative conditions such as arthritis, osteoporosis, atherosclerosis, and Alzheimer's disease. Current confusion regarding therapeutic efficacy of estrogen replacement therapy may be due to different estrogen formulations used, short term therapy, as well as advanced stage of the disease. MATERIALS AND METHODS: We compared anti-inflammatory activities of two major estrogen preparations, conjugated equine estrogen (CEE) and 17-beta estradiol, using an animal model (rat mesentery) of in vivo inflammatory reaction to intravenously infused amyloid-beta, examined by video recording and subsequently analyzed by transmission electron microscopy. Cellular markers of inflammation were monitored: leukocyte migration, platelet activation, mast cell activation/degranulation, and endothelial disruption. RESULTS: Low doses of CEE (0.3 mg/kg for 3 weeks) demonstrated significant anti-inflammatory activity, whereas even at high doses (2.0 mg) 17-beta estradiol had only minimal activity. CONCLUSION: CEE, a mixture of several compounds, may have some component(s) with significant anti-inflammatory activity. The anti-inflammatory activity of CEE may have a role in prevention of several degenerative diseases associated with menopause.

Amyloid beta-Peptides↗

PubMed1998

EMG-force relation in dynamically contracting cat plantaris muscle.

The purpose of this study was to revisit the electromyographical (EMG)-force relationship of dynamically contracting muscles using direct measurements of EMG and force in cat hindlimb muscles during locomotion. EMG signals were recorded from the plantaris muscle using bipolar indwelling wire electrodes, and the corresponding forces were measured using a tendon force transducer. Force-time histories of cat plantaris muscle were predicted by estimating selected force parameters from EMG and timing parameters, and then constructing two smoothly fitting quintic spline functions from the estimated force parameters. The force predictions did not contain information on force-length or force-velocity properties of the cat plantaris and did not use instantaneous contractile conditions as input. It was found that two smoothly fitting quintic spline functions provided the required properties to approximate plantaris force-time histories accurately, and approximations of the force-time histories using EMG and timing parameters as input for the quintic splines were good. The root mean square errors (RMS) of the predicted compared to the actual plantaris forces were smaller than corresponding results reported in the literature, even though the prediction model did not require the force-length-velocity properties or the instantaneous contractile conditions of the target muscles as input. From the results obtained in this study, it appears that force-time histories of the cat plantaris muscle during locomotion can be predicted adequately from information obtained using EMG and video records, without information on either the force-length and force-velocity properties, or the instantaneous contractile conditions of the muscle.

Algorithms↗

PubMed1996

Compromised microcirculation in acute murine Trypanosoma cruzi infection.

Microvascular compromise has been 1 of many factors implicated in the etiology of the cardiomyopathy associated with Chagas' disease. To further assess the effect of Trypanosoma cruzi infection on the microcirculation, we examined the cremaster microvascular model in CD-1 male mice infected with the Brazil strain at 20-25 days postinfection. There was a significant decrease in red cell velocity (Vrbc) in first and third-order arterioles and venules, which was reversed by verapamil treatment. Video recordings revealed a marked inflammatory response that was confirmed by transmission electron microscopy. A marked inflammatory response was not seen in verapamil-treated infected mice. Segmental vasospasm and dilatation was evident in the microvascular bed of infected mice. This was not seen in control or verapamil-treated mice. This model provides a readily accessible method to observe directly the effects of T. cruzi infection on the microcirculatory flow in vivo. In addition, it confirms and extends our previous observations regarding T. cruzi-associated microvascular spasm and underscores a role for verapamil, a calcium-channel blocker, in the amelioration of the Chagas' disease.

Acute Disease↗

PubMed1985

Assessment of effects of antiepileptic drugs.

Pharmacological studies form an important adjunct to epilepsy monitoring and conversely long-term EEG and video recording are of value for assessing antiepileptic drug (AED) effects. Clinical estimates of the incidence of brief frequent seizures as absences is often difficult but greater reliability can be achieved by long-term monitoring of the seizures themselves or of the associated EEG discharges. There are, however, very marked spontaneous short-term fluctuations in discharge rates and the amounts of ictal epileptiform activity in short conventional EEGs rarely provide any useful index of AED action. Acute investigations are of value for assessing new AEDs or experimental methods of administration and for pharmacokinetic studies. For this purpose either spontaneous EEG discharges or photosensitivity may provide quantitative measures of antiepileptic effect. Long-term AED monitoring by means of an indwelling catheter indicates the time course of blood drug levels to be more complex and variable than might be expected from simple pharmacokinetic models. Short-term fluctuations in AED concentrations have little effect on epileptiform EEG activity or seizure control but are often responsible for intermittent side-effects. Conversely diagnostic EEG and monitoring studies may be required to classify seizures as an aid to determining appropriate medication and may explain apparent resistance to therapy, due to pseudo-seizures, reflex or self-induced epilepsy. Finally a case is presented for combined pharmacological EEG and video-monitoring in the preliminary assessment of new AEDs in order to improve the design of subsequent clinical trials.

Anticonvulsants↗

PubMed2001

Technique for using video microscopy and indicator dilution for repeated measurements of cardiac output in small animals.

BACKGROUND: The authors developed an indicator dilution technique for small animals to repeatedly determine cardiac output and blood volume without cardiac instrumentation or blood sampling. METHODS: Observations were made in the hamster (N = 32, 70 mg/kg pentobarbital) cremaster using in vivo fluorescence videomicroscopy. Fluorescein isothiocyanate-conjugated bovine serum albumin (10 mg/ml) was injected as a bolus dose (right jugular) while video recording the light intensity in a 20-microm arteriole (intensified charge-coupled device [CCD] camera at fixed gain). The intensity signal was analyzed over time (background subtracted) and calibrated to the dye concentration. The ex vivo calibration was performed using a constant optical path length (20 microm) and a range of dye and hematocrit concentrations. In vivo tube hematocrit was determined using standard methods with fluorescently labeled erythrocytes. Thus, quenching of the fluorescence signal by hemoglobin was corrected for the calibration, and the plasma space in the arteriole was determined. The steady state dye concentration measured by the light intensity at 2 min was not different from the dye concentration found by direct spectrophotometric analysis of the plasma. RESULTS: Cardiac index was calculated as milliliters of blood per minute per kilogram body weight. The calculated cardiac index was 359 +/- 18 ml.min(-1).kg(-1), which is not different from the reported values for hamsters. Cardiac output was increased twofold when enough intravenous nitroprusside or nitroglycerine was injected to decrease mean arterial pressure from 90 to 70 mmHg. Cardiac output was elevated during dobutamine infusion (16 microg.kg(-1).min(-1)) and decreased during esmolol infusion (50, 75.kg(-1).min(-1)). Blood volume determined from the steady state dye concentrations was 6.2 +/- 0.5 ml/100 g body weight, within the normal range for hamsters. CONCLUSIONS: Fluorescent dye dilution and video microscopy can be used to repeatedly determine cardiac output or blood volume in small animals.

Animals↗

PubMed2001

Roles for 147 embryonic lethal genes on C.elegans chromosome I identified by RNA interference and video microscopy.

Early embryonic development involves complex events such as the regulation of cell division and the establishment of embryonic polarity. To identify genes involved in these events, we collected four-dimensional time-lapse video recordings of the first three cell divisions and analysed terminal phenotypes after RNA interference of 147 embryonic lethal genes previously identified in a systematic screen of Caenorhabditis elegans chromosome I. Over half gave defects in early processes such as meiosis, the assembly or position of the first mitotic spindle, cytokinesis, and proper nuclear positioning. For some phenotypic classes, the majority of genes are involved in a shared biochemical process. In addition, we identified loss-of-function phenotypes for genes of unknown function, but for which homologues exist in other organisms, shedding light on the function of these uncharacterized genes. When applied to the whole genome, this approach should identify the vast majority of genes required for early cell processes, paving the way for a greatly improved understanding of these processes and their regulation at the molecular level.

Animals↗

PubMed1995

Video microscopy of cerebrocortical capillary flow: response to hypotension and intracranial hypertension.

Although autoregulation of cerebral blood flow is well established, the response of cerebral capillary circulation to reduced cerebral perfusion pressure (CPP) is unclear. The objective of this study was to determine whether red cell flow velocity in individual capillaries of the cerebral cortex is maintained during acute decreases in CPP. Microcirculation of the superficial parietal cerebral cortex of adult barbiturate-anesthetized artificially ventilated rats was visualized using a new design of closed-perfused cranial window and epifluorescent-intensified video microscopy. Fluorescein-isothiocyanate-labeled red blood cells (FRBC) injected intravenously were used as markers of capillary flow. CPP, defined as mean arterial pressure minus intracranial pressure, was reduced by controlled hemorrhage or by stepwise elevation of local intracranial pressure. The movement of FRBC in the parenchymal capillary network was video recorded at each pressure level, and FRBC velocity in each capillary was measured off-line with use of the dual-window digital cross-correlation technique. FRBC flux in the capillaries was measured by automated cell counting. FRBC velocity at normal perfusion pressure was 1.47 +/- 0.58 (SD) mm/s and changed little in the perfusion pressure range of 70-120 mmHg. The autoregulatory index in this pressure range was 0.0049 mm.s-1.mmHg-1. Opening of previously unperfused capillaries was not observed. FRBC flux correlated with FRBC velocity, but the latter was maintained in a narrower range than FRBC flux, suggesting a decrease in capillary diameter or hematocrit with decreasing perfusion pressure. The results suggest that flow autoregulation is associated with the maintenance of capillary flow velocity and that capillary recruitment does not contribute to flow autoregulation in the rat cerebral cortex.

Animals↗

PubMed1994

Endothelin-1 is involved in hepatic sinusoidal vasoconstriction after ischemia and reperfusion.

Endothelin-1 (ET-1), a vasoactive peptide, causes a significant rise in portal vein pressure, which is most likely a result of severe vasoconstriction in the liver. In this study, the effect of ET-1 on sinusoidal vasoconstriction in the liver after ischemia and reperfusion was directly investigated using intravital microscopy. In anesthetized female Sprague Dawley rats (200-250 g) ischemia of the median and left liver lobes was induced for 90 min by temporary ligation of the left pedicle. After declamping and a 90-min reperfusion period, the livers were exposed for intravital microscopy. Using a Nikon MM-11 fluorescence microscope (545 nm, 330x), a CCD camera (Cohu FK 6990), and a SVHS video recording unit, the hepatic microcirculation was directly investigated. Besides sham groups, two ischemia groups were studied, receiving ET-1 antiserum (anti-ET-1; 0.5 ml; Peptide Inst., Osaka, Japan) or NaCl 0.9% (0.5 ml) 5 min prior to reperfusion of the liver (n = 6/group). Following a transient drop in the mean arterial blood pressure in the anti-ET-1-treated groups, comparable systemic hemodynamic conditions among the four groups were noted during intravital microscopic assessment at the end of the 90-min reperfusion period. Reduction in the sinusoidal diameters during postischemic reperfusion (7.7 +/- 0.5 microm) was prevented by anti-ET-1 treatment (9.6 +/- 0.25 microm; P < 0.01; mean + SEM) back to control values (9.6 +/- 0.32 microm), while most of other microcirculatory parameters did not show significant differences. The results supported further the role of ET-1 in dysregulation of the sinusoidal vascular tone in the liver, e.g., after ischemia and reperfusion.

Animals↗

PubMed2005

Mode and determination of the initial contraction stage in the mouse embryo heart.

The developing mammalian heart initiates spontaneous contractions shortly after the myocardium differentiates from the splanchnic mesoderm. The precise timing and mode of the onset of heartbeat, however, have not been statistically described in mice. We analyzed the patterns of contractive activity in video-recorded heart regions ranging from the pre-somite stage to day 10.5 (E10.5). The first sign was detected at the 3-somite stage (E8.25), when a few cardiac myocytes constituted small contracting groups on both sides of the heart tube. Fluctuations of the basal [Ca2+]i level were detected in dormant 3-somite-stage hearts, indicating the initiation of electrical activity before visible contractions. After weak and irregular contractions at the 3-somite stage, the contractions were almost coordinated as early as the 4-somite stage. Unidirectional blood flow through the atrioventricular canal was established around the 20-somite stage at E9.25, correlated with the development of the endocardial cushion. We propose that not only the endocardial cushion but also coordinated contractions are essential for unidirectional flow, because induced bradycardia due to short exposure at room temperature caused regurgitation at E10.5 when otherwise highly organized flow was observed. These findings complement and extend earlier observations on functional heart development, providing a reference for fundamental research on mammalian cardiogenesis.

Animals↗

PubMed1999

An intrinsic timer that controls cell-cycle withdrawal in cultured cardiac myocytes.

Developing cardiac myocytes divide a limited number of times before they stop and terminally differentiate, but the mechanism that stops their division is unknown. To help study the stopping mechanism, we defined conditions under which embryonic rat cardiac myocytes cultured in serum-free medium proliferate and exit the cell cycle on a schedule that closely resembles that seen in vivo. The culture medium contains FGF-1 and FGF-2, which stimulate cell proliferation, and thyroid hormone, which seems to be necessary for stable cell-cycle exit. Time-lapse video recording shows that the cells within a clone tend to divide a similar number of times before they stop, whereas cells in different clones divide a variable number of times before they stop. Cells cultured at 33 degrees C divide more slowly but stop dividing at around the same time as cells cultured at 37 degrees C, having undergone fewer divisions. Together, these findings suggest that an intrinsic timer helps control when cardiac myocytes withdraw from the cell cycle and that the timer does not operate by simply counting cell divisions. We provide evidence that the cyclin-dependent kinase inhibitors p18 and p27 may be part of the timer and that thyroid hormone may help developing cardiac myocytes stably withdraw from the cell cycle.

Animals↗