Optical properties of porcine skin dermis between 900 nm and 1500 nm

The weak absorption of shortwave infrared light by skin tissues between 700 and 1500 nm offers an important window for diagnosis by optical means. The strong scattering of shortwave infrared light by the skin, however, presents a challenge to the modelling of light propagation through the skin and the understanding of skin optics. We have measured the collimated and diffuse transmittance and diffuse reflectance of porcine skin dermis samples within 30 h post-mortem. Monte Carlo simulations have been performed to inversely determine the absorption coefficient, scattering coefficient and anisotropy factor of the dermis samples in the spectral range from 900 to 1500 nm. We further analyse the sensitivity of the values of the parameters to the experimental errors and inverse calculation procedures. The state of the cellular integrity of the skin samples following optical measurements was verified using transmission electron microscopy. These results were correlated to study post-mortem effects on the in vitro optical properties of porcine dermis. We concluded that for samples stored within crushed ice for up to 30 h post-mortem the wavelength dependence of optical properties of the dermis remains unchanged while the values of the parameters vary moderately due to modification of the water content of the tissue.     

Sweet's syndrome and subacute thyroiditis

A 63 year old woman developed biopsy documented lesions of acute febrile neutrophilic dermatosis (Sweet's syndrome) one week after the onset of subacute thyroiditis. This is only the second reported case of such an association. The role of cytokines in the development of both subacute thyroiditis and Sweet's syndrome may be the link between these two conditions.     

Ethanol drinking following 6-OHDA lesions of nucleus accumbens and tuberculum olfactorium of the rat

Previous studies have shown that lesions of the dopaminergic system in the brain produced by an intracerebroventricular injection of the neurotoxin, 6-hydroxydopamine (6-OHDA), evoke significant changes in ethanol drinking. In the present experiments, dopaminergic systems of Sprague-Dawley rats were lesioned by 6-OHDA infused into either the tuberculum olfactorium or nucleus accumbens, two of the structures implicated in drug-related reinforcement. Prior to the lesion and immediately thereafter, tests for ethanol preference were undertaken in which water was offered in a self-selection situation together with ethanol which was increased in concentration from 3-30% over a 10-day interval. Following the circumscribed ablation of dopaminergic neurons within either the N. accumbens or tuberculum olfactorium, preference for ethanol increased significantly with absolute intakes exceeding 4.0 g/kg at the 7% concentration during the first postlesion drinking test. During the second postlesion preference test, the mean consumption of ethanol exceeded 6.0 g/kg at the 11% concentration and 4.0 to 5.0 g/kg at the 20 and 30 percent concentrations offered to the rats. When adjacent areas just dorsal or lateral to these structures were lesioned by 6-OHDA, no significant change in consumption of ethanol occurred. Thus, it is envisaged that one of the functional roles for the dopaminergic neurons of the N. accumbens and tuberculum olfactorium is to regulate the craving for a drug with addictive liability such as ethanol. As a result of an impairment of normal function of dopamine receptors or a perturbation in the release of this catecholaminergic neurotransmitter, ethanol becomes reinforcing upon repeated exposure. Thus, an addictive-like state consequently ensues. Finally, it is envisaged that the control mechanism underlying the function of the dopaminergic neurons in the medial-basal forebrain is functionally disinhibited in individuals that consume ethanol to the point of abuse.     

Spurennachweis. Leichenerscheinungen. Technik

Ohne Zusammenfassung     

Effect of intraperitoneal versus intravenous glucose administration on laser Doppler flow in murine FSaII tumors and normal skin

The effects of i.p. versus i.v. glucose administration on laser Doppler flow (LDF) were studied in peripheral tissue areas of murine FSaII tumors implanted s.c. in the hind foot dorsum and in normal skin of conscious C3Hf/Sed mice. LDF was monitored prior to and continuously for 90 min following the administration of glucose, galactose, or mannitol at doses of 5 or 10 mg/g. Results showed that i.p. administration of hyperosmolar solutions was followed by a substantial, dose-dependent flow reduction which was indistinguishable for the various agents at equal osmotic load, and similar in tumor tissue and normal skin. Reductions in LDF are, therefore, primarily caused by hypovolemic hemoconcentration following i.p. administration of hyperosmolar sugar solutions. In contrast, i.v. administration of these solutions at 5 mg/g caused an initial flow increase (most probably due to a transient hypervolemic hemodilution), with a return to baseline readings within 5-10 min. At 10 mg/g i.v., a biphasic change in LDF occurred with an initial, temporary increase and a significant decline thereafter with no recovery within the observation period. This drop in LDF most probably is due to a decrease in cardiac output and an increase in viscous resistance to flow. Since comparable changes were observed with all agents and in both tissues investigated, it is concluded that the alterations in flow pattern following injection of hyperosmolar solutions are neither glucose nor tissue specific. Glucose- or tumor-specific effects, if present at all, must be of secondary importance in the animal model chosen.