Immunohistochemical demonstration of hyaluronan and its possible involvement in axolotl neural crest cell migration.

Hyaluronan (HA), an extracellular matrix component, is involved mainly in the control of cell proliferation, neural crest and tumor cell migration, and wound repair. We investigated the effect of hyaluronan on neural crest (NC) cell migration and its ultrastructural localization in dark (wild-type) and white mutant embryos of the Mexican axolotl (Ambystoma mexicanum, Amphibia). The axolotl system is an accepted model for studying mechanisms of NC cell migration. Using a biotinylated hyaluronan binding protein (HABP), major extracellular matrix (ECM) spaces, including those of NC cell migration, reacted equally positive on cryosections through dark and white embryos. Since neural crest-derived pigment cells migrate only in subepidermal spaces of dark embryos, HA does not seem to influence crest cell migration in vivo. However, when tested on different alternating substrates in vitro, migrating NC cells in dark and white embryos prefer HA to fibronectin. In vivo, such an HA migration stimulating effect might exist as well, but be counteracted to differing degrees in dark and white embryos. The ultrastructural localization of HA was studied by means of transmission electron microscopic immunohistochemistry using HABP and different protocols of standard chemical fixation, cryofixation, embedding, and immunolabeling. The binding reaction of HA to HABP was strong and showed an equal distribution throughout ECM spaces after both standard chemical fixation/freeze substitution and cryofixation. A preference for the somite or subepidermal side was not observed. Following standard fixation/freeze substitution HABP-labeled "honeycomb"-like networks reminiscent of fixation artifacts were more prominent than labeled fibrillar or irregular net-like structures. The latter predominated in adequately frozen specimens following high-pressure freezing/freeze substitution. For this reason fibrillar or irregular net-like structures very likely represent hyaluronan in the complex subepidermal matrix of the axolotl embryo in its native arrangement.

Effects of elevated intraocular pressure on haemoglobin oxygenation in the rabbit optic nerve head: a microendoscopical study.

Intraocular pressure dependent reactions of optic nerve head vasculature and intracapillary haemoglobin oxygenation (HbO(2); oxygen saturation) were studied in the center and at the rim of the rabbit optic nerve head (ONH) as well as in the choroid, by a new combination of microendoscopy and simultaneous haemoglobin spectrophotometry. In 13 anesthetized albino rabbits the vasculature and the intracapillary Hb-oxygenation were studied by a microendoscope which was introduced into the eye bulb. Photometric measurements were performed via a beam splitter with the Erlangen micro-lightguide spectrophotometer (EMPHO) from the center of the endoscopic picture. The haemoglobin oxygenation was calculated by real time analysis of the spectral curves. Intraocular pressure was elevated stepwise from 20-80 mmHg. At the rim of the optic nerve head the vascular diameters as well as the intracapillary HbO(2)-values were stable till an intraocular pressure of 60 mmHg and decrease after IOP elevation to 70 and 80 mmHg. In contrast, in the center of the optic nerve head and in the choroid these parameters decline already from 40-50 mmHg on. At an IOP of 60 mmHg (P<0.01) and 70 mmHg (P<0.05) HbO(2)is significantly lower in the ONH center than at the rim. In the center and the choroid HbO(2)is well maintained between 20 and 40 mmHg. After pressure release at the end of the experiment HbO(2)increased to 94.3+/-4.6% (rim) and 98.8+/-1.5% (center) of the initial value at 20 mmHg (difference not significant).By the high spatial resolution of this new optical method we were able to demonstrate that the center of the optic nerve head is more sensitive to changes in intraocular pressure than the optic nerve head rim. Thus, tissue damage after critical haemodynamic and oxygenation parameters seems more probable in the relatively poor perfused center of the ONH than in the overperfused rim.

Effects of heat shock on the functional morphology of cell organelles observed by video-enhanced microscopy.

In living astrocytes and MDCK cells we observed morphological phenomena during and after heat shock (HS) utilizing our new perfusable microchamber system, which monitors pH, pO(2), pCO(2), and temperature. By means of electronic light microscopy and confocal laser scanning microscopy, mitochondria were demonstrated to swell and to reduce their motility. The specific fluorescent probe MitoTracker Green revealed that the mitochondrial morphology changed from a rodlike into an annular shape with a central vacuole-findings which were corroborated by transmission electron microscopy. After HS (shift from 37 degrees C to 45 degrees C for 15 min) the mitochondrial membrane potential (DeltaPsi(m)) was depressed in most but not all mitochondria as monitored with the fluorescent probe JC-1. The dual emission images of JC-1 illustrated a heterogeneous red staining of distinct areas of single mitochondria. The shape changes as well as the drop of the membrane potential of the mitochondria indicated severe cellular stress and a direct intervention on the mitochondrial permeability transition.

A new perfusion cell chamber system for determination of heat shock effects by means of video-enhanced microscopy.

A user friendly microscope perfusion chamber which allows real-time observation of individual cells at high magnification has been designed. An integrated multisensor was used to monitor the cell culture conditions. To prove the potential of the system heat shock experiments were performed. By means of video-enhanced contrast microscopy (VECM) the mitochondria morphology of cultured astrocytes was demonstrated to change from a rod-like to an annular shape after heat shock. For further analyses mitochondria were stained on the microscope stage.

Clinical test of a blood pressure measurement device with a wrist cuff.

OBJECTIVE: To test a semi-automatic oscillometric blood pressure measurement device with a wrist cuff. METHODS: Two different test methods, partly based on European and American standards for clinical investigation of non-invasive sphygmomanometers, were worked out and compared. Mostly German guidelines were considered. The reference measurement was always performed using the standard auscultatory method on the upper arm. Altogether, 404 comparative measurements were performed in 108 patients. RESULTS: The mean differences (oscillometric wrist values minus auscultatory reference values) were -2.5+/-8.5 mmHg (mean +/- SD) for systolic blood pressure and -3.3+/-6.7 mmHg for diastolic blood pressure in method 1, and -3.6+/-6.9 mmHg for systolic blood pressure and -3.7+/-4.8 mmHg for diastolic blood pressure in method 2. The calculated correlation coefficients were betewen 0.77 and 0.89. A grading analysis was performed using the cumulative percentages of readings which showed a difference between test and reference measurements larger than 5, 10 and 15 mmHg. CONCLUSION:

Oscillometric blood pressure measurement: description of the method used.

There is no general valid and thus no recognized standard method of evaluation for oscillometric blood pressure measurement. This applies in particular to the determination of blood pressure parameters-systolic, diastolic and mean blood pressure-using a cuff pressure oscillogram. For this reason- and given that today's users are faced with an overwhelming choice of oscillometric blood pressure measuring devices-performance and function are very topical issues. The status and importance of oscillometric blood pressure measurement are inferred from an analysis of trends in the development of non-invasive blood pressure measurement. Oscillometric measurement is described from the point of view of signal analysis, and methods for identifying blood pressure parameters are presented. A check list has been compiled in the form of a questionnaire to help the user assess the performance and function of oscillometric blood pressure measuring devices. Instructions for use are given to avoid handling errors.

[Preliminary clinical comparative study of a new blood pressure instrument with wrist cuff]. / Erste klinische Vergleichsuntersuchung eines neuen Blutdruckmessgerätes mit Handgelenkmanschette.

The present article reports on the first test results of a new oscillometric blood pressure device with a wrist cuff in clinical application. The test was performed in two different methodical studies. Both studies included 154 patients, from which 542 comparative measurements were acquired. The evaluated mean differences of systolic and diastolic blood pressures are -for study 1-1.2 mmHg (standard deviation +/- 7.9 mmHg) and 0.9 mmHg (+/- 6.2 mmHg), for study 2 1.6 mmHg (+/- 7.4 mmHg) and 3.5 mmHg (+/- 6.7 mmHg) and show a good agreement with the method of Riva-Rocci/Korotkoff. The results are discussed in detail and conclusions for applicable fields of use for the device and for additional clinical studies are drawn.