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Biomedical subjects

R R Anderson

Publications and source records attributed to R R Anderson.

At least 163 records · Page 9Linked to original sources
PubMed1987

Melanosomes are a primary target of Q-switched ruby laser irradiation in guinea pig skin.

The specific targeting of melanosomes may allow for laser therapy of pigmented cutaneous lesions. The mechanism of selective destruction of pigmented cells by various lasers, however, has not been fully clarified. Black, brown, and albino guinea pigs were exposed to optical pulses at various radiant exposure doses from a Q-switched, 40 nsec, 694 nm ruby laser. Biopsies were analyzed by light and electron microscopy (EM). Albino animals failed to develop clinical or microscopic evidence of cutaneous injury after irradiation. In both black and brown animals, the clinical threshold for gross change was 0.4 J/cm2, which produced an ash-white spot. By light microscopy, alterations appeared at 0.3 J/cm2 and included separation at the dermoepidermal junction, and the formation of vacuolated epidermal cells with a peripheral cytoplasmic condensation of pigment. By EM, enlarged melanosomes with a central lucent zone were observed within affected epidermal cells at 0.3 J/cm2. At 0.8 and 1.2 J/cm2, individual melanosomes were more intensely damaged and disruption of melanosomes deep in the hair papillae was observed. Dermal-epidermal blisters were formed precisely at the lamina lucida, leaving basal cell membranes and hemidesmosomes intact. Possible mechanisms for melanosomal injury are discussed. These observations show that the effects of the Q-switched ruby laser are melanin-specific and melanin-dependent, and may be useful in the selective destruction of pigmented as well as superficial cutaneous lesions.

Animals↗
PubMed1987

Concentration of thyroid hormones and prolactin in dairy cattle serum and milk at three stages of lactation.

Eighteen lactating Holstein cows were used with six each in early, mid, and late lactation. Blood samples were obtained on 7 successive d. Blood serum and milk were measured by radioimmunoassay for thyroxine, 3,5,3'-triiodothyronine, and 3,3',5'-triiodothyronine. Prolactin was also measured in serum by radioimmunoassay. Serum thyroxine increased as lactation progressed and milk production declined (50, 55, and 62 ng/ml). Serum concentrations of triiodothyronine and reverse triiodothyronine were unchanged throughout lactation. Prolactin in serum declined as lactation advanced linearly (14.4, 11.8, and 10.5 ng/ml). Concentrations of thyroxine and triiodothyronine in milk declined significantly between early and mid but not mid and late lactation. Reverse triiodothyronine in milk did not change over the lactation. Serum triiodothyronine contained 1200 to 1300 pg/ml, whereas that in milk was 200 to 300 pg/ml. Reverse triiodothyronine was over 300 pg/ml in serum and only 80 to 90 pg/ml in milk. Amounts of thyroxine and triiodothyronine available to offspring from milk were calculated to be minor sources (4 to 5%) of total requirements for maintenance of metabolic function.

Animals↗
PubMed1987

The effects of four levels of endophyte-infected fescue seed in the diet of pregnant pony mares.

Mean weight of 20 Quarter Horse placentas on a wet basis was 3.27 +/- 0.17 kg. These placentas contained mean dry fat-free tissue, DNA, RNA and collagen weights of 411 +/- 24 g, 11.2 +/- 0.6 g, 12.4 +/- 0.7 g and 210 +/- 15 g, respectively. In Ponies and Quarter Horses, there was a trend towards a decrease in these 4 values as gestation length increased. Analysis of placentas of Ponies fed different amounts of endophyte fungus-infected fescue seed showed that weight of dry fat-free tissue increased with increasing percentages of fescue seed in the diet. Diets containing fescue seed resulted in heavier placentas containing more dry fat-free tissue, DNA, RNA and collagen than placentas from mares fed the control diet containing no fescue seed. In mares fed 45% fescue seed, 3 of the 5 foals born suffered from abnormalities: 2 died and one was saved from suffocation in the placenta. No effects of toxic tall fescue were apparent in foals from mares fed the lower levels of fescue seed (15 or 30%).

Animals↗
PubMed1987

[Selective photothermolysis: contribution to the treatment of flat angiomas (port wine stains) by laser].

Since 1962, lasers have been used in dermatology and have become the first choice in the treatment of superficial, vascular ectasia. Lasers are unique sources of light; they are coherent, monochromatic, collimated and intense. By careful selection of wavelength, pulse duration, and intensity, it is often possible to selectively confine a laser effect to a specific histologic structure in tissue, depending upon the tissue properties. The ideal treatment of Port Wine Stains (PWS) should irreversibly damage the ectatic vessels but minimize heating of the epidermis and superficial dermis. A theory, called selective photothermolysis, predicts the optimal combination of laser parameters of achieving this ideal treatment of PWS to be a wavelength of 577 nm, a pulse duration of 0.35-10 msec, and an energy per surface area of about 7-8 J/cm2. Laser wavelength: The wavelength of 577 nm is preferred because it: maximizes the selective absorption by hemoglobin, minimizes absorption by epidermal melanin, provides sufficient depth of penetration in the blood to coagulate 0.1 mm vessels allows penetration of light into dermis up to 1 mm. Laser pulse duration: A pulse-width in the range of 0.35-10 msec allows the temperature elevation to be uniform inside the vessel and to be confined to the vessel area. Shorter pulses superheat the red blood cells causing explosive boiling and hemorrhage. Longer pulses allow heat to diffuse away from vessels, requiring greater energies per pulse to achieve vessel damage. An increased energy per pulse increases the risk of excessive damage to surrounding tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Tunable dye laser (577 nm) treatment of port wine stains.

Despite steady improvement in the laser treatment of port wine stains (PWS), hypertrophic scarring remains a serious side-effect in approximately 10% of patients. The tunable dye laser (577 nm) has been shown to cause selective vascular destruction in normal and PWS skin. We have treated ten patients using a tunable dye laser (577 nm, 300 mu sec) resulting in clearing of the PWS without any evidence of hypertrophic scarring. Treatment requires no anesthesia or wound care, and there were no postoperative infections.

Adolescent↗
PubMed1986

Control of mammary gland fibroblast growth by insulin, growth hormone and prolactin.

Fibroblasts isolated from guinea pig mammary glands were cultured in 96 well culture plates in the presence of various concentrations of insulin, growth hormone and prolactin. Insulin (30 micrograms/ml increased uptake of tritiated thymidine by 30%. Higher concentrations of insulin did not result in any further increase in thymidine uptake. Growth hormone alone did not alter thymidine uptake in concentrations of 0 to 250 ng/ml. 300 ng/ml gave thymidine uptake of 136% of controls. In the presence of 20 g/ml insulin, growth hormone (250 ng/ml) increased thymidine uptake to approximately double that of controls. Prolactin alone (300 ng/ml decreased thymidine uptake by 19%. Insulin increased thymidine uptake, but the negative effect of prolactin was still evident above 150 ng/ml.

Animals↗
PubMed1986

Selective ablation of atheromas using a flashlamp-excited dye laser at 465 nm.

Ablation of human atheromas with laser pulses that had only a small effect on normal artery tissue was shown in vitro in air and under saline using 1-mu sec pulses at 465 nm from a flashlamp-excited dye laser. At this wavelength, there is preferential absorption in atheromas due to carotenoids. The threshold fluence for ablation was 6.8 +/- 2.0 J/cm2 for atheromas and 15.9 +/- 2.2 J/cm2 for normal aorta tissue. At a fluence of 18 J/cm2 per pulse, the ablated mass per unit of energy ranged from 161 to 370 micrograms/J for atheromas and from 50 to 74 micrograms/J for normal aorta tissue. Ablation products consisted of cholesterol crystals, shredded collagen fibers, and small bits of calcific material. Most debris was less than 100 micron in diameter, but a few pieces were as large as 300 micron. High-speed photography of ablation in air suggested explosive ejection of debris, caused by vapor formation, at speeds on the scale of 300 m/sec. Histological analysis showed minimal thermal damage to residual tissue. These data indicate that selective laser ablation of atheromas is possible in vitro.

Arteriosclerosis↗
PubMed1986

Effect of dye laser pulse duration on selective cutaneous vascular injury.

The pulsed dye laser at 577 nm, a wavelength well absorbed by oxyhemoglobin, causes highly selective thermal injury to cutaneous blood vessels. Confinement of thermal damage to microvessels is, in theory, related to the laser exposure time (pulsewidth) on selective vascular injury. This study investigates the effect of 577 nm dye laser pulsewidth on selective vascular injury. Nine Caucasian, normal volunteers received 577 nm dye laser exposures at pulsewidths of 1.5-350 microseconds to their skin. Clinical purpura threshold exposure doses were determined in each volunteer, and biopsies of threshold and suprathreshold doses were examined in each volunteer. The laser exposure dose required to produce purpura increased as pulsewidth increased in all 9 subjects (p less than 0.001). This finding corresponds to laser pulsewidths equal to or exceeding the thermal relaxation times for dermal blood vessels. Histologically, vessel damage was selectively, but qualitatively, different for short vs long pulsewidths. Pulsewidths shorter than 20 microseconds caused vessel wall fragmentation and hemorrhage, whereas longer pulsewidths caused no significant hemorrhage. The purpura noted clinically appears to be due to a coagulum of intralumenal denatured erythrocytes. At 24 h, there was marked vessel wall necrosis at all pulsewidths. The short pulsewidths may cause erythrocyte vaporization, rapid thermal expansion, and mechanical vessel rupture with hemorrhage. Long pulsewidths appear to cause thermal denaturation with less mechanical vessel damage. The selective, nonhemorrhagic, vascular necrosis caused by the long-pulsewidth dye laser may lead to a more desirable clinical outcome in the therapy of blood vessel disease processes.

Capillary Permeability↗
PubMed1986

Changes in macroingredients of guinea pig milk through lactation.

Milk samples were collected daily from English short-hair albino guinea pigs for 21 d. Analyses included protein, fat, lactose, ash, calories, and specific gravity. All components except lactose increased in concentration gradually from the beginning to end of lactation. Protein percentage began at 6% on d 1 and was 14% on d 21. The pattern of increase was either quadratic or exponential but not rectilinear. Patterns were similar for fat, ash, and calories. Fat on d 1 was 5.6% and 9.0% on d 20. Ash was .97% on d 1 and 1.4% on d 19. Calories per gram milk were 939 on d 1, increasing gradually to 1874 on d 21. Lactose dropped from 5.5% on d 1 to 5.0% on d 2. It remained at 5% until d 6, when it began a gradual decline to .5% on d 20. Thickening of milk and increasing concentrations of protein, fat, ash, and calories, as well as a marked drop in milk volume, resulted from the precipitous decline in lactose concentration of .27%/d from d 6 to 21. Because lactose is the primary controller of osmotic equilibrium and, therefore, the primary regulator of the water content of milk, its decrease in concentration explains the decline in milk volume and the concomitant increases in fat, protein, and solids from d 6 to the end of lactation.

Animals↗
PubMed1986

Histologic responses of port-wine stains treated by argon, carbon dioxide, and tunable dye lasers. A preliminary report.

Although the blue-green argon laser light has been used successfully to treat port-wine stains (PWSs) for many years, it produces substantial epidermal damage. We have previously shown in normal human skin that pulsed yellow tunable dye lasers (577-nm wavelength) can cause highly selective damage to cutaneous microvessels with minimal injury to the overlying epidermis. Pulsed tunable dye lasers also produce selective vascular injury in the abnormal vessels of PWSs, with clinically apparent lightening of the lesions. Both epidermal injury and fibrosis are less severe with this laser treatment than with argon and carbon dioxide laser treatments. Clinical and histologic responses of PWSs treated by argon, CO2, and pulsed yellow dye lasers were compared and followed up for one month in three patients. Although larger and longer-term clinical trials are necessary to fully evaluate this new treatment modality, it appears that pulsed yellow laser radiation offers a more selective, less traumatic, and probably superior form of treatment for PWSs.

Adult↗
PubMed1986

Internally referenced ImmunoConcentration assays.

We have developed a method for incorporating an internal reference zone in addition to the test zone in a single immunoConcentration device. We have illustrated the method by constructing an internally referenced assay for human choriogonadotropin (HCG) in serum. The internally referenced assay, which can be performed in about 5 min, provides a measured overall precision (CV) of approximately 15% at a concentration, in serum, of approximately 50 int. units/L. The test zone consists of an anti-HCG antibody adsorbed onto latex microspheres and entrapped within a porous support. The reference zone contains antibody against alkaline phosphatase (EC 3.1.3.1), which has also been adsorbed onto latex microspheres and trapped within the support. The use of an internal reference moderates the effects of variations in assay conditions on the interpretation of assay results.

Alkaline Phosphatase↗
PubMed1985

Relationship between milk production and mammary gland indices of guinea pigs.

Regression analysis related simulated production to simulated wet weight of mammary gland, weight of dry fat-free tissue, deoxyribonucleic acid content, and ribonucleic acid content for the first 21 days of lactation of the guinea pig. Coefficients of determination were .52 for wet weight, .03 for dry fat-free tissue, .84 for deoxyribonucleic acid, and .20 for ribonucleic acid. Coefficients of determination were larger when ascending and descending phases of lactation were considered separately. Milk production per unit mammary wet weight, dry fat-free tissue, deoxyribonucleic acid, and ribonucleic acid were related to day of lactation by an equation of the form Y = aXbecX, where Y was milk production per unit mammary gland growth, X was day of lactation, e was the base of natural logarithms, and a, b, and c were constants. Efficiency of milk production, defined as milk production per unit mammary size, increased with increasing milk yield.

Animals↗
PubMed1985

Interspecies variation in mammary gland growth rate: relationship to gestation length.

Growth of the mammary gland is measured by several indices including total wet weight, dry fat-free tissue, and deoxyribonucleic acid. The latter is a superior measure of true growth because it represents changes of cell numbers. Sufficient data have been generated to determine the relationship among species of mammals between gestation length and differences in rates of mammary growth. Exponential growth equations were estimated for eight mammalian species with gestation lengths from 16.5 d for the hamster to 280 d for the cow. The form of the most appropriate equation was Y = AeBx, where Y is mammary deoxyribonucleic acid or dry fat-free tissue, x is day of gestation, e is the base of natural logs, and A and B are constants. The A term was related to body weight (W) and the B-term to gestation length (G). Resulting equations were deoxyribonucleic acid (mg) = .0547W.803 e1.98 G-.98x and dry fat-free tissue (mg) = 2.35W.779 e.719 G-.77x. First-order rate constants of mammary growth ranged in a reverse order from a high of .141 d-1 in hamsters to a low of .008 d-1 in cows; in other words, mammary deoxyribonucleic acid in hamsters doubled in 4.9 d but in the bovine it took 87 d to double.

Animals↗
PubMed1984

Effect of estradiol and relaxin on collagen and non-collagen protein synthesis by mammary fibroblasts.

In order to determine the effect of relaxin and estradiol on collagen and noncollagen synthesis by mammary gland fibroblasts, fibroblasts isolated from guinea pig mammary glands were grown on plastic or Cytodex-3 collagen coated microcarriers. On plastic, estradiol (600 pg/ml) increased the incorporation of tritiated glycine into collagen. Non-collagenous protein synthesis was increased at all concentrations of estradiol, but it was greatest with 200 pg/ml estradiol. On Cytodex-3, 400 pg/ml estradiol increased the synthesis of collagen and non-collagenous protein. Relaxin (1 microgram/ml) did not affect collagen synthesis but decreased the synthesis of non-collagenous protein.

Animals↗
PubMed1984

Effect of preirradiation tissue target temperature upon selective vascular damage induced by 577-nm tunable dye laser pulses.

The effect of hamster cheek pouch temperature upon the microvascular injury induced by pulsed laser dye radiation was studied. An appropriate wavelength (577 nm) and pulse width (300 nsec) were delivered by a flashlamp-pumped dye laser to induce selective vascular damage, as previously described. With increasing pulse energies, transient slowing of blood flow, stasis with brown discoloration of blood, and hemorrhage were observed. Cooling the cheek pouch to 8 degrees before irradiation increased the laser exposure threshold for induction of such injury. Measurement of the exposure thresholds for hemorrhage at different temperatures suggests that microvessels are heated to between 90 and 100 degrees, before hemorrhage occurs. These data are consistent with microvaporization as a major event in the sequence leading to hemorrhage, but do not exclude other possible mechanisms.

Animals↗
PubMed1984

Effect of estradiol and relaxin on growth of fibroblastic cells isolated from guinea pig mammary glands.

Fibroblasts were isolated from the mammary glands of guinea pigs and grown in 96-well culture plates. They were treated with a factorial arrangement of porcine relaxin (0.0, 0.5, 1.0 or 1.5 micrograms/ml) and estradiol-17 beta (0, 200, 400 or 600 pg/ml). Tritiated thymidine or uridine was added to a final activity of 25 nCi per well and the cells incubated at 37 degrees C for 48 h. Cells were then harvested onto filter paper and counted for tritium. Controls (0.0 micrograms/ml relaxin and 0 pg/ml estradiol) incorporated 3.7 nCi of tritiated thymidine and 4.8 nCi tritiated uridine. Both relaxin and estradiol altered the incorporation of thymidine and uridine. There was also an interaction between the two hormones. Thymidine incorporation with no estradiol and 1.5 micrograms/ml relaxin was 129% of controls. The optimum incorporation of thymidine occurred with 0.5 micrograms/ml relaxin and 400 pg/ml estradiol. This combination of hormones gave a response of 145% of controls. Uridine incorporation followed a different pattern. Relaxin alone at a concentration of 1.5 micrograms/ml gave a near-optimum response of 141% of control. The optimum combination of relaxin and estradiol for uridine incorporation was 1.5 micrograms/ml relaxin and 400 pg/ml estradiol, which gave a response of 156% of controls. These data indicated that relaxin and estradiol alter DNA and RNA synthesis in mammary fibroblasts and thus may be important in controlling the growth of the mammary gland stroma.

Animals↗
PubMed1984

Prolonged skin photosensitization induced by methoxsalen and subphototoxic UVA irradiation.

Topical 8-methoxypsoralen (8-MOP) was used to briefly provide free psoralen sufficient for marked cutaneous photosensitization, but only a small dose of UVA was delivered initially, in an effort to produce many monoadducts but few crosslinks. After ample time for clearance of the remaining free psoralen a second UVA exposure was delivered. The second exposure should not have generated any additional monoadducts in the absence of free psoralen, but the remaining monoadducts could be converted to crosslinks. The observation of a prolonged persistent UVA-photosensitive state caused by prior, very small doses of UVA given while free 8-MOP was present strongly suggests that psoralen-DNA crosslinks per se initiate much of the phototoxic effect of 8-MOP on skin, and that monoadducts induce much less acute inflammatory response. Because erythema was studied as the end point, the data say nothing about relative contributions of monoadducts vs crosslinks in causing mutagenesis, hyperpigmentation, therapeutic or other cutaneous responses. Other explanations for the induced persistent photosensitive state are also possible, but less tenable or entirely hypothetical.

DNA↗