S. el-Gammal

A wound healing model with sonographic monitoring

The methods used hitherto for quantification of skin repair processes only allow an examiner a two‐dimensional assessment of superficial wound healing. With the recent advent of high frequency B‐scan ultrasonography in dermatology it has become possible to follow the course of healing and evaluate the healing processes in deeper layers of the skin. In this investigation 80 patients received cryosurgery for treatment of basal cell carcinomas on the face or neck region. As the size of cryosurgical defects can be precisely controlled they are potentially useful as standardized wound healing models. The course of wound healing after cryosurgery using a digital ultrasound scanner (DUB 20, Taberna pro medicum, Lüneburg, Germany) was monitored. The usable depth of penetration of the echo signal is ≈200μm, the axial resolution ∼80 μm. The cryolesion and the repair processes were examined ultrasonographically and clinically over a period of at least 3 weeks or until the wound had completely healed. The depth of invasion and lateral extent of the basal cell carcinoma as well as the size of the induced cryolesion can be determined by ultrasound. The exudative phase after cryosurgery, with developing oedema and necrosis, can be quantified on the basis of the reduced reflectivity in the corium. The repair processes taking place in the region of necrosis can be visualized in the ultrasound scan. The ultrasonically monitored wound healing model which we have demonstrated is particularly suitable for investigating the efficacy of drugs which promote healing.

Evaluation of the Efficacy of H1 Blockers by Noninvasive Measurement Techniques

BACKGROUND Evaluation techniques for determining the strength of action and the onset of activity of H1 receptor blockers have not yet been sufficiently standardized. OBJECTIVE The clinical efficacy of the H1 receptor blocker loratadine was to be measured upon a wheal response subsequent to an intracutaneous injection of 0.1 ml histamine (0.1%). METHODS In a pilot study, 10 patients were treated with the H1 receptor blocker loratadine for a period of 7 days. Various noninvasive measurement techniques, i.e. 20-MHz sonography, laser-Doppler flowmetry, chromatometry using the Lab* system and computer-assisted planimetry, were applied to provide a quantitative evaluation of the wheal and the marginal erythema. Using these quantification methods, the development of the urticarial reaction 20 min after injection and its decline were evaluated. RESULTS The urticarial reaction was reduced substantially under treatment with 10 mg loratadine over a period of 7 days. The methods we used could accurately quantify different aspects of the urticarial reaction noninvasively. CONCLUSIONS All of the chosen measurement techniques are widely recognized. For objective assessment of the urticarial reaction with high-frequency ultrasound, we recommend the measurement of the distance between skin entrance echo and fascia since the demarcation of the wheal is often impossible by ultrasound. In order to improve comparison of results of various workgroups in the future, we therefore suggest the use of the selected combination of noninvasive procedures as a standard for evaluating the efficacy of H1 receptor blockers.

The paracrystalline structure of an insect rhabdomere (Calliphora erythrocephala)

SummaryBy use of a modified fixation technique, the receptor cells of the compound eye of the blowfly Calliphora erythrocephala were found to contain a regular, paracrystalline array of alternating rows of hexagonally shaped microvilli. The receptor cells R1 to R6 have a cell-specific number of microvilli per row in a cross section. Every microvillus has a filament cluster connecting the axial skeleton with the microvillar membrane. This cluster is preferentially right-left oriented relative to the longitudinal axis of the microvillar array. Three adjacent microvilli are interconnected by an electron-dense substance. A mirroring technique indicated that this intermicrovillar structure consists of three subunits, although these subunits could not be conclusively demonstrated by classical densitometry or image subtraction techniques. The electron-dense substance can be seen in all cross sections of the proximal and distal parts of the microvilli. They are cylindrical structures separating the microvilli along their entire length. It is suggested that these cylindrical aggregates contain an enzymatic complex separating the rhodopsin-containing microvillar membrane into six compartments.

A quantitative freeze-etching study on the effects of cytochalasin B, colchicine and concanavalin A on the formation of intercellular contacts in vitro☆

The effects of concanavalin A (conA), cytochalasin B (CB), and colchicine acting on cell membrane-associated structures, such as surface receptors or submembranal cytoskeletal components, were studied in trypsin-isolated plexus cells reaggregated in vitro. Following reaggregation, these cells form intercellular contacts, i.e. a zonula occludens (ZO) and integrated nexus (gap junctions, GJ). In the control cultures the GJ occupied 4.7%, the tight junctions (TJ) occupied 14 microns/microns2 of the surface of the zonula occludens (ZO). All the drugs/lectins studied inhibit contact formation in a characteristic manner. ConA inhibits the formation of GJ (1% of the ZO) and causes 5 times more defective TJ strands than the controls. CB inhibits the assembly of the TJ (75% of the controls) and the GJ (1% of the ZO) when it is administered during the period of contract formation. Colchicine inhibits the formation of GJ (1% of the ZO) and produces 2.5 times more open-end strands of TJ than the controls. All effects are reversible with the exception that integrated GJ are not re-formed after colchicine administration. It is suggested that an intact interaction between surface receptors, intramembranous particles and associated cytoskeletal structures is necessary for remodelling cellular contacts.

The development of the diencephalic choroid plexus in the chick

SummaryThe surface morphology of the diencephalic choroid plexus (Pl. ch. v. III) was investigated by light microscopy and scanning electron microscopy in chicks from the 7th embryonic day (ED) to the 8th week after hatching. Pl. ch. v. III develops on the anterior ventricular roof from a sagittally oriented fold and a few posteriorly located transverse folds. On the 7th ED no significant differences in the cell surface morphology between Pl. ch. v. III and the surrounding ependyma are observed: both are covered with cilia. During the next four days, long cell prolongations (one per cell) covered with microvilli develop first on the surface of the posterior ventricular roof and then on the posterior part of Pl. ch. v. III. These structures are transitory. On the 11th ED, round cell prolongations (one per cell) appear progressively on the entire plexus, also replacing the long ones. Now the plexus surface is distinct from the surface of the surrounding ependyma. During the last week before hatching and also after hatching, the round cell prolongations become less prominent. Simultaneously, the number of cilia per unit surface area diminishes.With consideration of earlier reports, this study suggests that the following factors are involved in the increase of the surface area of Pl. ch. v. III: (I) The pseudostratified epithelium changes into columnar epithelium. (2) Ependymal elements of the posterior roof of the 3rd ventricle contribute to the anlage of Pl. ch. v. III. In later stages, however, Pl. ch. v. III grows only by mitoses.

Regional surface changes during the development of the telencephalic choroid plexus in the chick

SummaryThe surface morphology of the developing chick telencephalic choroid plexus (TCP) was examined by scanning electron and light microscopy. A blunt evagination develops rostro-cranially to the foramen of Monro on the medial telencephalic septum. The pseudostratified TCP epithelium differs in its surface morphology from that of the surrounding ependyma. Subsequently the TCP becomes elongated and branches. On the 9th embryonic day (ED) the pseudostratified epithelium progressively becomes high columnar epithelium in a distal to proximal direction along the branches of the TCP. The apical poles of the high columnar epithelial cells protrude into the ventricular lumen. Later, additional branches sprout at the base of the TCP, which then resembles a tree with a bush growing at its roots. Before the time of hatching, the high columnar epithelium changes to low columnar epithelium again in a distal to proximal direction. The surface of the TCP becomes flatter, in the process of which the number of cilia per unit surface area is reduced. On the developing TCP the epiplexus cells vary in shape, depending upon their functional state.It is proposed that not only the morphological but also the functional differentiation of the TCP proceeds in a distal to proximal direction along the branches of the choroid plexus. The surface differentiation of the TCP has a more regular character than that of the diencephalic CP (DCP), described previously, which seems to be influenced in its development by other anatomical structures.

High-Frequency Ultrasound: A Noninvasive Method for Use in Dermatology

In internal medicine and surgery diagnostic imaging methods have found wide application. This is, among other reasons, due to the fact that organ systems have to be treated which are not directly accessible to the physician. Of the imaging methods in use today, ultrasound has gained particularly wide acceptance, since it is harmless to the patient and can be repeated as many times as necessary.

150 Mhz Adaptive Ultrasound Imaging of the Eye and Skin

The growing interest in high resolution noninvasive imaging gave rise to the development of high frequency ultrasound imaging systems1,2,3,4. A major design problem concerning these broadband systems is caused by the strong dispersive attenuation of the tissue, which results in inhomogeneous images with poor signal to noise ratio (SNR). To address the noise problem, strongly focused transducers with high energy density in a narrow focal region are utilized, which also provide more isotropic images due to improved lateral resolution. To account for the short depth of the focal area a suitable imaging conception, the B/Z-scan concept5 is used. To avoid the inhomo-geneity of the images, different transmitter signals for each depth are applied, which are pseudoinversely prefiltered according to the transfer function of the covering tissue. To gain signal energy required for inverse filtering, a pulse compression technique with nonlinearly frequency modulated chirp signals is utilized6,7.

Three-Dimensional Shaded Surface Reconstructions of Cardiac and Paracardiac Structures

The medical ultrasound imaging systems in use today make two-dimensional sections of different organs available. By rotating, translating and tilting the B-scan applicator, a sequence of ultrasound images is available which is eventually processed and synthetically reassembled by the brain of an experienced examiner to give him a spacial understanding of structure interaction. Presently, this intraindividual imagination cannot be objectified and therefore cannot be documented.