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Biomedical subjects

G W Kalmus

Publications and source records attributed to G W Kalmus.

At least 19 recordsLinked to original sources
PubMed2002

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 degrees 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.

Animals↗
PubMed2001

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.

Animals↗
PubMed1997

Absorption spectra of corneas in the far ultraviolet region.

PURPOSE: To study the corneal absorption in the far ultraviolet (UV) region between 260 and 190 nm. METHODS: Thirty-four corneal samples of thickness near 20 microns were obtained from 18 porcine corneas and six human corneas with a microtome-cryostat. The authors conducted absorbance measurements of the sectioned corneal samples supported by two UV optical windows from 350 to 190 nm using a dual-beam spectrophotometer. Three whole porcine corneas were used to study the effect of freezing on the absorbance from 350 to near 290 nm. RESULTS: The absorption spectra of porcine and human corneas from 350 to 190 nm were measured and three segments in the spectrum between 260 and 190 nm have been identified. The linear absorption coefficients were determined to be 2300 +/- 330 (cm-1) at 210 nm and 2410 +/- 370 (cm-1) at 193 nm for the porcine corneas and 2320 +/- 470 (cm-1) at 210 nm and 2340 +/- 150 (cm-1) at 193 nm for the human corneas. CONCLUSIONS: A "window of ablation" in the far UV region between 220 and 190 nm has been identified in which short laser pulses of similar durations and different wavelengths may be interchangeable to ablate the corneal surface with similar characteristics.

Animals↗
PubMed1996

Alcohol intake in high alcohol drinking (HAD) rats is suppressed by FG5865, a novel 5-HT1A agonist/5-HT2 antagonist.

Both the 5-HT2 antagonist, FG5606 (amperozide), and the mixed 5-HT1 agonist/5-HT2 antagonist, FG5893, attenuate significantly the volitional intake of alcohol in the cyanamide treated rat. The purpose of the present study was to investigate the effect on alcohol drinking in the selectively bred, high alcohol drinking (HAD) rat of a new and novel 5-HT1A agonist/5-HT2 antagonist, FG5865 (2-[4-[4,4-bis(4-fluorophenyl)butyl]-1-piperazinyl]-3-pyridinecarboxy lic acid methyl ester), which shares pharmacological properties with FG5893. Initially, a standard three bottle preference test for water vs. 3% to 30% alcohol solutions was given over 11 days to determine the maximally preferred concentration for each animal. Then water and this solution, which ranged between 9% and 20% with an overall mean absolute intake of 6.3 +/- 0.5 g/kg per day, was offered over three consecutive 4-day test sequences: (1) predrug control; (2) SC injections b.i.d. of either 1.0 mg/kg or 2.5 mg/kg FG5865 or saline control vehicle; and (3) postdrug. Whereas saline failed to alter alcohol consumption of the HAD rats, FG5865 caused a significant dose dependent reduction by as much as 75% in the intakes of alcohol during its administration in terms of both g/kg (p < 0.01) and proportion of alcohol to total fluid intake (p < 0.01). During the administration of 2.5 mg/kg FG5865, alcohol drinking declined from 6.5 +/- 0.3 g/kg to as low as 2.3 +/- 0.2 g/kg per day. Neither the body weight of the HAD animals nor their intake of food was affected by either dose of FG5865. These results uphold the concept that the 5-HT1A and 5-HT2 receptor subtypes in the brain play a part in the aberrant drinking of alcohol of the HAD rat. Because FG5865 influences the activity of serotonergic neurons in the mesolimbic system of the rat, it is envisaged that the drug suppresses alcohol drinking by way of its action on these neurons.

Alcohol Drinking↗
PubMed1995

Cirrhosis with ascites: increased atrial natriuretic peptide messenger RNA expression in rat ventricle.

BACKGROUND/AIMS: Atrial natriuretic peptides (ANPs) are increased in the circulation of cirrhotics with ascites; however, it is unknown whether this increase is caused by increased synthesis or a decrease in the metabolic processing of these peptides. ANP gene expression in the liver, atria, ventricles, and gastrointestinal tract of cirrhotic vs. control rats was studied as was their metabolism. METHODS: Sprague-Dawley rats developed cirrhosis with ascites approximately 20 weeks after weekly intragastric instillation of carbon tetrachloride. Their circulating, ascitic, and urinary levels of ANPs were measured by radioimmunoassays. ANP gene expression was measured by a ribonuclease protection assay. RESULTS: ANP gene expression was increased 2.8- to 4.1-fold in the ventricles of cirrhotic rats compared with age-matched healthy rats. ANP gene expression was present but not increased in the liver, atria, and gastrointestinal tract of cirrhotic rats. No increase of metabolic processing of these peptides was found in the circulation. Cardiac ultrasonography and catheterization revealed no ventricular dilation or increased ventricular pressure. CONCLUSIONS: Elevation of circulating ANPs with cirrhosis was associated with increased ventricular steady-state ANP messenger RNA concentrations. The increased ANP gene expression in cirrhosis seems to involve a novel mechanism not related to stretch because neither increased ventricular pressure nor dilation was present.

Analysis of Variance↗
PubMed1992

The cytoprotective properties of prostaglandin E2 against the toxic effects of actinomycin C on embryonic neural retina cells.

Prostaglandins (PGs) have been shown to cytoprotect various tissue types against the toxic effects of many chemicals. The mechanism of this protection is poorly understood, but the involvement of cAMP is often implied. Only one previous study examined nervous tissue and PG protection. The present study was designed to determine if PGE2 affords cytoprotection to a more specific nervous tissue (embryonic neural retina) from the toxicity of actinomycin C (AMC) using a trypan blue exclusion assay. The lowest concentration of PGE2 (2 x 10(-5)M) had no effect, but as the concentration increased (3 x 10(-5)M and 5 x 10(-5)M), PGE2 did afford protection against AMC in a dose dependent fashion. Theophylline treated cells were not protected, suggesting that cAMP may not be the primary mechanism of protection.

Animals↗
PubMed1992

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.

Arachidonic Acid↗
PubMed1989

Effects of ethanol and acetaldehyde on cultured pre-implantation mouse embryos.

Pre-implantation 2-cell stage mouse embryos, obtained from superovulated CF-1 mice, were exposed to ethanol and acetaldehyde through the culture medium for 60 min followed by a 105-h incubation period. Control and ethanol exposed embryos survived equally well in ethanol concentrations as high as 800 mg/100 ml medium and acetaldehyde levels up to 10 mg/100 ml medium.

Acetaldehyde↗
PubMed1984

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.

Alcohol Oxidoreductases↗
PubMed1982

The influence of cyclic nucleotides on macromolecular synthesis in cultured neural retina cells.

1. The effect of cyclic nucleotides on aggregates of dispersed embryonic neural retina cells was examined in order to study their influence upon macromolecular synthesis, i.e. protein and DNA. 2. Cyclic AMP, dibutyryl cAMP, cyclic GMP and dibutyryl cGMP were used at various concentrations (5 x 10(-4) -5 mM). 3. The incorporation of labeled precursors into DNA and protein were used to monitor the effect of cyclic nucleotides on cultured aggregates. 4. All nucleotides exhibited a stimulatory effect at 5 x 10(-4) and 5 x 10(-3) mM on macromolecular synthesis, with resulting growth and proliferation of chick neural retina cells. 5. High concentrations (5 x 10(-1) and 5 mM) of cyclic nucleotides exhibited an inhibitory effect upon macromolecular synthesis and a marked cytotoxic effect.

Animals↗
PubMed1978

Studies on dispersed unincubated chick blastoderm cells. I. Early phases of aggregation.

Early phases of aggregation of dispersed unincubated chick blastoderm cells were investigated. Dispersed cells, when maintained in appropriate cultures, began adhering to one another almost immediately and eventually formed spherical aggregates without any recognizable structures except for occasional blood islands, after 24 hr of incubation. The number and size of aggregates derived from dispersed cells depended largely upon the speed of rotation and initial cell density. Treatment with colchicine (4 microgram/ml) had no apparent effect on adhesion of cells, although it yielded smaller aggregates than controls, especially after 14 hr of incubation. Direct observation on mitotic activity, estimations of cell number and nucleic acid content, and pulse labeling experiments with 3H thymidine clearly showed that aggregates were derived entirely from adhesion of free cells and/or fusion of smaller aggregates during the first 12 to 13 hr of incubation. In addition, all cell types present in the unincubated blastoderm contributed to the formation of aggregates, not one particular cell type.

Animals↗
PubMed1978

Studies on dispersed unincubated chick blastoderm cells. II. Formation of contacts and cell sorting in aggregates of unincubated chick blastoderm and heart cells.

The configuration of blastoderm-heart cell aggregates after cell sorting depended largely on the proportion of each cell type initially present in the culture. In heterotypic aggregates, blastoderm cells were always found to partially or completely surround heart cells with both cell types retaining their characteristic morphology. Specialized junctions (e.g. desmosomes) developed only between cells of the same type. These observations suggest that blastoderm cells are unable to recognize and form stable contacts with heart cells.

Animals↗