Gerhard W. Kalmus

Brain growth during ethanol-induced hypoplasia

The inhibition of fetal brain growth resulting from in utero ethanol exposure may impair central nervous system (CNS) development and thereby result in mental retardation. Studies of ethanol-induced brain hypoplasia using chick embryos have shown that the early development of the chick is significantly growth inhibited by a single dose of ethanol (1.0 g/kg) given at the start of incubation (day 0). However, this level of ethanol exposure has been reported to have no effect on chick weight measured at hatching, suggesting that the weights of ethanol-treated chicks were regained during their development. The present experiments were undertaken to determine the biochemical changes associated with the varying growth rates believed to occur in the alcohol-treated embryos. The results indicated that between days 5 and 8 of development, the rates of DNA and protein synthesis (measured as radioactive thymidine and leucine incorporation, respectively) were inhibited by ethanol. The growth inhibition was highly correlated with blood alcohol content and there were associated increases in brain prostaglandin E (PGE) levels relative to vehicle-treated embryos. Further, there was a significant, inverse correlation between brain cyclic AMP content and individual brain weight. By day 10, the ethanol-treated embryos remained smaller than controls but their rates of DNA and protein synthesis were comparable to those of control animals. The normal rates of synthesis observed on day 10 appeared to correlate with clearance of the ethanol dose and with restoration of normal brain levels of PGE relative to 10-day vehicle-dosed embryos.

Alcohol dehydrogenase activity in the developing chick embryo

Before day 9 of incubation, chick embryos contain no measurable alcohol dehydrogenase (ADH) activity. Following day 9 of incubation, chick embryo liver ADH activity increases as a linear function of liver mass. A single dose of ethanol given at the start of incubation is cleared only slowly prior to day 9 of incubation but is completely cleared by day 13. Chick embryo liver ADH has two detectable isozymes throughout development. The percentage contribution of each isozyme to total ADH activity does not change significantly during development. The Km apparent of chick liver ADH is significantly increased shortly after hatching relative to the Km apparent of embryonic ADH. Ethanol exposure during incubation has no effect on the development of ADH activity or isozyme distribution.

Mechanism study of porcine skin ablation by nanosecond laser pulses at 1064, 532, 266, and 213 nm

The ablation mechanism of fresh porcine skin has been studied using nanosecond laser pulses at the wavelengths of 1064, 532, 266, and 213 nm. We have identified the Na spectral line at 589 nm in the secondary radiation from the ablated skin sample as the signature of tissue ablation and measured the ablation probability near ablation threshold. Ablation depth per pulse has been measured by histological examination of ablated skin samples. Review of the ablation probability data through probit analysis indicated that the same mechanism is likely to be operative for tissue ablation at all four wavelengths. Various soft tissue ablation models are discussed, and it is concluded that the ablation of the skin by nanosecond laser pulses from 1064 to 213 nm is a result of electronic impact ionization which leads to the formation of a plasma.

In Vivo Study of Intradermal Focusing for Tattoo Removal

Delivery of intradermally focused nanosecond laser pulses with small energy as an alternate technique applicable to clinical procedures in dermatological and plastic surgery is an area of relatively new interest with multiple potential applications. We assessed this approach on common tattoo pigments in dermis in an in vivo study using a wavelength of 1064 nm. Paired micropigs were tattooed with standard blue, black, green and red pigments. The tattoos were allowed to mature and then treated by 12 ns pulses in a focused beam of 11.4° cone angle. Visual observation and histological analysis of biopsies were performed to evaluate results. Significant reduction in pulse energy and collateral damage was achieved with pulse energy ranging between 38 to 63 mJ. Blue and black tattoos were found to respond well from a clinical standpoint. The depth dependence of tissue response and pigment redistributions at 1 hour, 1 week and 1 month after laser treatment was quantitatively analysed through biopsies and a strong relationship was demonstrated between tattoo response and laser-induced dermal vacuolation. The optical absorption coefficients of the four tattoo pigments were measured to be approximately the same and the laser-induced plasma is suggested to be responsible for the pigment redistribution. As we hypothesised, intradermal focusing of nanosecond pulses significantly reduced required pulse energy for tattoo ablation to about 60 mJ or less. These results stimulate a number of additional questions relevant not only to clinical applications but also to the understanding of the fundamental process of laser–pigment interaction in the dermis as it relates to tattoo removal.

Experimental study of optical properties of porcine skin dermis from 900 to 1500 nm

The weak absorption of near-IR light by skin tissue has offered an important optical window for diagnostic possibilities with optical means including optical biopsy. The strong scattering of the near-IR light by skin tissue, however, presents a great challenge to the modeling of light propagation through and the optical measurement of the tissue. We have measured transmittance and reflectance of fresh porcine skin and performed Monte Carlo simulations to inversely determine the absorption coefficient, scattering coefficient and asymmetric coefficient of tissue samples in the spectral range from 900 to 1500nm. The state of cellular integrity following optical measurements was verified using transmission electron microscopy. These results were correlated with the possible effects on the measurements of the tissue optical properties.

Ablation of skin tissue by nanosecond laser pulses at 1064, 532, 266, and 213 nm

The ablation of porcine skin tissue has been investigated using nanosecond (ns) laser pulses at the wavelengths of 1064, 532 and 266 nm. The ablation probability has been measured near the threshold through detection of the secondary radiation from the tissue sample surface at different wavelengths. Experimental results have indicated that the ablation of the skin tissue in the wide range of ablating wavelength is caused by optical breakdown induced by the strong electromagnetic field of the nanosecond pulses. Furthermore, we conclude that the initial seed electrons acquire ionization energy from the incident optical field mainly through a momentum-relaxing drift mechanism.

The effects of indomethacin on fibroblast chemotaxis

1. Boyden chambers were used to investigate the effects of indomethacin on fibroblast chemotaxis to a conditioned medium. 2. It was determined that indomethacin did not inhibit, but enhanced fibroblast chemotaxis at a concentration of 10(-4) (91%)-10(-6) M (79%). 3. No significant difference was found between controls and cells treated with 10(-8)-10(-10) M indomethacin.

Tattoo removal in micropigs with low-energy pulses from a Q-switched Nd:YAG laser at 1064 nm

Treatment of pigmented lesions in skin with visible or near- infrared nanosecond (ns) laser pulses often causes significant collateral tissue damage because the current approach uses pulses with energy of 300 mJ or larger. Additionally, this requires large Q-switched laser systems. To overcome these disadvantages, we have investigated a different approach in delivering ns laser pulses for cutaneous lesion treatment. Tattoo removal in an animal model with a focused laser beam from a Q-switched Nd:YAG laser has been investigated in two Yucatan micropigs tattooed with blue, black, green and red pigments. The tattoos were treated with a focused beam of 12-ns pulses at 1064 nm, with different depth under the skin surface, while the micropig was translated to achieve an effect of single pulse per ablation site in the skin. With the pulse energy reduced to a range from 38 to 63 mJ, we found that nearly complete clearance was achieved for blue and black tattoos while clearance of red and green tattoos was incomplete. Analysis of the skin appearance suggested that the pulse energy can be decreased to below 20 mJ which may lead to further reduction of the collateral tissue damage and improve the clearance of red and green tattoos.

Surface ablation of porcine skin tissue using nanosecond laser pulses at 1064 nm

A selective photothermolysis model has been widely used to explain skin tissue ablation by nanosecond laser pulses. Nevertheless, fundamental questions regarding the mechanism underlying the ablation process remain to be answered. We have investigated the surface ablation of fresh porcine skin tissue with 8 ns pulses at 1064 nm and its dependence on spot size. Histology analysis of the ablated tissue samples has been conducted. From these preliminary results we have plotted the ablation depth per pulse as a function of laser fluence at different spot sizes.

The Influence of Oxidizing Agents on Macromolecular Synthesis for Chitinous Material

Summary The 5th instar larvae of the common flour beetle, Tribolium confusum, was utilized as an invertebrate model to test the larvicidal potential of oxidizing agents used as flour preservatives. Larvae were exposed to 10 ppm of either diflubenzuron or benzoyl peroxide. Results showed decreases in both total protein and glucose concentrations. Histological examination also indicated smaller deposition of chitinous material in the endocuticle. Both treatments had similar effects. Thus, these data indicate that oxidizing agents mixed in flour may be used for the control of development of flour beetle larvae.