Anti-inflammatory role of sympathetic nerves in chronic intestinal inflammation.

BACKGROUND: Substance P (SP) is a pro-inflammatory neuropeptide in colitis, whereas sympathetic neurotransmitters are anti-inflammatory at high concentrations. AIM AND METHODS: In all layers of the colon, nerve fibre densities of SP(+) and sympathetic nerve fibres were investigated (22 Crohn's disease, six diverticulitis, and 22 controls). In addition, the nerve fibre repellent factor semaphorin 3C (SEMA3C) was studied. The functional role of the sympathetic nervous system was tested in dextran sodium sulfate (DSS) and Il10(-/-) colitis. RESULTS: In all layers, Crohn's disease patients demonstrated a loss of sympathetic nerve fibres. Sprouting of SP(+) nerve fibres was particularly observed in the mucosa and muscular layer in Crohn's disease. SEMA3C was detected in epithelial cells, and there was a marked increase of SEMA3C-positive crypts in the mucosa of Crohn's disease patients compared to controls. In Crohn's disease, the number of SEMA3C-positive crypts was negatively related to the density of mucosal sympathetic nerve fibres. Sympathectomy reduced acute DSS colitis but increased chronic DSS colitis. Sympathectomy also increased chronic colitis in Il10(-/-) mice. CONCLUSIONS: This study demonstrated a loss of sympathetic and an increase of SP(+) nerve fibres in Crohn's disease. SEMA3C, a sympathetic nerve repellent factor, is highly expressed in the epithelium of Crohn's disease patients. In chronic experimental colitis, the sympathetic nervous system confers an anti-inflammatory influence. Thus, the loss of sympathetic nerve fibres in the chronic phase of the disease is most probably a pro-inflammatory signal, which might be related to repulsion of these fibres by SEMA3C and other repellents.

Artificial light sources for simulating natural daylight and skylight.

A review of the literature reveals the need for reliable and stable artificial light sources that can be used as simulators of daylight and skylight. In quest of such simulators a first requirement is quantitative information on the average spectral distributions of natural sources such as daylight and skylight. Recent investigations of the spectral energy characteristics of natural daylight and skylight made it possible to determine such average conditions. With these conditions established, a search was undertaken for an artificial light source that would simulate these average natural distributions with a minimum of filtering. Certain fluorescent lamps and combinations of them were considered first, but, although it was possible to achieve fairly good visual matches of daylight and skylight, the spectral characteristics and the variability of such combinations are drawbacks to their use in critical scientific work. For this purpose, therefore, xenon arc lamps were found to be superior.

A Photomechanical Device for Triggering Digital Output on a GE Spectrophotometer.

Most applications of modern spectrophotometry demand that spectrophotometric measurements be recorded on media suitable for direct use by data processing equipment. This paper describes a photomechanical method for actuating the readout command for an old model GE recording spectrophotometer. This instrument has nonlinear wavelength representation in the near ultraviolet and near infrared. The method involves an opaque disk having a direct one-to-one rotation relation with the wavelength drive. The disk contains three sets of small holes on the circumference of concentric circles which represent the near ultraviolet, visible, and near infrared regions of the spectrum. The accurate angular separation of these holes, along with a photodiode and lamp which are aligned for each set of holes, makes available a selection of these three ranges and automatically actuates the readout command in the control chassis at 10-nm intervals for all wavelength ranges. The data are then punched into cards by an IBM 526 summary punch. The option of taking data at 5-nm intervals is provided by a suitable second disk.

Optical sphere paint and a working standard of reflectance.

Specially prepared barium sulfate powders and coatings of these powders with polyvinyl alcohol have been used as working standards of reflectance and for coating integrating spheres. These materials are satisfactory for use in the wavelength range 0.20-2.00 micro. Since the refractive index of barium sulfate is rather low, it is necessary to use fairly thick layers in order to obtain good results. The absolute value of luminous reflectance of the barium sulfate powder, described in this paper, is 0.995 +/- 0.001, and that of the paint, when properly applied, is 0.992 +/- 0.001. The spectral reflectance of this material is higher than that of magnesium oxide, particularly in the uv region of the spectrum. By using barium sulfate as reference standard and as a coating on the integrating spheres of spectrophotometers, it is now possible to measure spectral reflectance reliably in the uv region to 200 nm. Because the reflectance of barium sulfate paint is significantly greater than that of magnes um oxide in the shortwave region, there is a corresponding gain in instrument sensitivity when barium sulfate is used as a sphere coating and as a comparison material.

Determination of polarization in optical instruments and its metrological implications.

One of the working programs of the CIE Technical Committee on Photometric and Radiometric Characteristics of Materials (CIE, TC-2.3) deals with polarization problems. The subcommittee working on this program is concerned with those topics of polarization that deal with the photometric and radiometric characteristics, particularly with instrumental polarization, which causes unpredictable variation in light transmitted, reflected, absorbed, or emitted-quantities all dependent on the sample type and measurement configurations. We present in this paper in summary form the results of some of the work that was reported at the Committee Meeting in London, England, in July 1973.

Spectral emission of corona discharges.

Corona-discharge devices are commonly used in a variety of research and development applications. They are known to produce a considerable amount of electromagnetic radiation, mainly in the uv region of the spectrum. The mechanism involved is presumed to be the ionization and radiative recombination of the gases surrounding the high-voltage terminal of the device. A series of high-resolution emission spectra of corona discharge has been measured in atmospheres of nitrogen, helium, and air. (The nitrogen and helium are Air Products 99.995% purity, total hydrocarbons less than 0.5 ppm.) These data are presented here and are compared with published spectroscopic reference data. All the emission lines reported in the spectroscopic reference literature were detected, as well as other lines, which may conceivably be due to impurities.

Derivative absorption and emission spectrophotometry.

Derivative spectrophotometry has been shown to have many important applications: for example, studying composition and reaction processes; providing gas signatures; detecting trace chemicals. This technique can become a powerful means for analyzing isomers used in polymer production. In this report, practical examples are given which typify applications of the derivative spectra. Conventional absorption and emission spectra often present overlapping bands not easily resolved by conventional means; band resolution usually is facilitated by first-and second-derivative spectra obtained from spectrophotometric measurements. Numerical methods based on both off-line and on-line computer processing are presented for generating first-and second-derivative spectra, and these techniques are discussed fully. With these methods, the contribution of background noise is emphasized. Ways to reduce this noise are given.

Absolute Luminescence Spectra via Digital-Technique and Time-Resolved Spectroscopy.

Most instruments intended for luminescence spectroscopy fall in the category of uncorrected spectrofluorimeters. In many routine analyses, uncorrected spectra are useful, especially if they do not have to be compared with others from different laboratories. However, for theoretical work, results must be on an absolute basis. This paper describes a method and the related equipment that have been developed and used to obtain, on an absolute basis, many of the parameters that are important in photochemical research. The system can provide absolute emission spectra, absolute excitation spectra, and quantum efficiencies for luminescence, fluorescence, delayed fluorescence, and phosphorescence. Also, it can measure the half-life of phosphorescence and of delayed fluorescence. Provision is made for the independent and continuous control of the time between excitation and detection pulses, thus allowing the measurement of the half-life at any wavelength of emission. With these provisions it is possible to resolve overlapping fluorescence, delayed fluorescence, and phosphorescence spectra.