PubMed Health⌕ Search

Biomedical subjects

R R Warner

Publications and source records attributed to R R Warner.

At least 19 recordsLinked to original sources
PubMed2001

Historical overfishing and the recent collapse of coastal ecosystems.

Ecological extinction caused by overfishing precedes all other pervasive human disturbance to coastal ecosystems, including pollution, degradation of water quality, and anthropogenic climate change. Historical abundances of large consumer species were fantastically large in comparison with recent observations. Paleoecological, archaeological, and historical data show that time lags of decades to centuries occurred between the onset of overfishing and consequent changes in ecological communities, because unfished species of similar trophic level assumed the ecological roles of overfished species until they too were overfished or died of epidemic diseases related to overcrowding. Retrospective data not only help to clarify underlying causes and rates of ecological change, but they also demonstrate achievable goals for restoration and management of coastal ecosystems that could not even be contemplated based on the limited perspective of recent observations alone.

Animals↗
PubMed2001

Dandruff has an altered stratum corneum ultrastructure that is improved with zinc pyrithione shampoo.

Transmission electron microscopy of scalp tape strips indicates that dandruff scalp possesses abnormal stratum corneum (SC) ultrastructure that is normalized by treatment with small-particle zinc pyrithione (ZPT). Similar abnormalities occur throughout the scalp of those with dandruff, even where no flaking is present. SC abnormalities are consistent with hyperproliferation, including parakeratosis, lipid droplets within corneocytes, few desmosomes, corneocyte membrane interdigitation, and excessive disorganized intercellular lipid. Reversal of SC abnormalities would require treatment of the cause(s) of dandruff, not merely flake removal. A protocol was developed to quantify scalp structural abnormalities by scoring cells from scalp tape strips for yeast number, amount of intercellular lipid, normal intercellular lipid structures, prevalence of intracellular lipid droplets, parakeratotic corneocytes, and corneocyte interdigitation. This protocol was used to compare dandruff and normal SC to dandruff SC treated with either commercial ZPT-containing shampoo or a placebo. Treatment with commercial ZPT shampoo significantly returned SC ultrastructure to normal, suggesting control of the cause of dandruff.

Female↗
PubMed2000

Relative fitness components measured with competitive PCR.

In mating systems with sperm competition, paternity is frequently established with modern DNA techniques. These methods are often expensive and cumbersome, and can be especially difficult for highly fecund species. An additional objective of many paternity studies is to discover the relationship between sperm number and paternity. We present here a competitive polymerase chain reaction (PCR) protocol, coupled with the use of an automated sequencer, that has two functions: (i) to measure directly relative sperm output of males in sperm competition; and (ii) to estimate paternity distributions of large numbers of offspring simultaneously. Our technique was calibrated using a microsatellite locus of the bluehead wrasse, Thalassoma bifasciatum, with the result that product ratio after competitive PCR accurately reflected the initial template proportions of known mixtures of DNA. When we applied our technique to multiple larvae of separate mating events we found that paternity distributions estimated with the competitive PCR technique closely matched the estimates derived from the traditional method of pooling paternity data from individual larvae. Finally, we compared paternity of these spawns with relative sperm contribution estimates. This comparison suggests that ejaculate size alone does not predict a male's proportion of paternity within the group.

Animals↗
PubMed2000

Characterization of vernix caseosa: water content, morphology, and elemental analysis.

Recent studies have prompted interest in the use of epidermal barrier creams as protective biofilms for very low birthweight preterm infants. The key to understanding the role of epidermal barrier films is an elucidation of their interaction with water and a basic knowledge of their composition. In this study, we investigated the morphologic properties and elemental composition of the naturally occurring biofilm, vernix caseosa. This biofilm is typically lacking in preterm infants and its production coincides in utero with terminal differentiation of the epidermis and formation of the stratum corneum. Significantly, vernix (80.5+/-1.0% H2O) had a much higher water content than other barrier creams (Eucerin: 17.1+/-0.6%, Aquaphor: 0.33+/-0.03%, Ilex: 0.19+/-0.02%, petrolatum: 0.03+/-0.01%; all p<0.05). Phase contrast microscopy of vernix showed multiple cellular elements with nucleic "ghosts" embedded in a putative lipid matrix. Transmission electron microscopy revealed flattened structures approximately 1-2 microm in thickness with distinct cellular envelopes indicative of differentiated corneocytes. Compared with mature corneocytes in adult stratum corneum, vernix corneocytes appeared swollen, the density of the keratin filaments was less, and there was a relative lack of tonofilament orientation. Cryofractured specimens were examined by cryoscanning electron microscopy with subsequent elemental localization by X-ray beam analysis. The findings indicate the high water content of vernix is largely compartmentalized within fetal corneocytes. These results are consistent with the novel view of vernix as a "fluid phase" stratum corneum consisting of a hydrophobic lipid matrix with embedded fetal corneocytes possessing unique biomechanical and water-binding properties.

Elements↗
PubMed2000

Hypothalamic arginine vasotocin mRNA abundance variation across sexes and with sex change in a coral reef fish.

Gonadal hormones are important mediators of sexual and aggressive behavior in vertebrates. Recent evidence suggests that the peptide hormones arginine vasotocin (AVT) and its mammalian homologue arginine vasopressin (AVP) often critically mediate these gonadal hormone effects on behavior and have direct influences on behavioral variation. Behavioral differences between sexes, across reproductive states, and even among closely related species are correlated with differences in central AVT/AVP systems in many species. We report differences in hypothalamic AVT mRNA levels between distinct alternate male phenotypes and with female-to-male sex change in the bluehead wrasse (Thalassoma bifasciatum), a teleost fish. The aggressively dominant and strongly courting male phenotype has greater numbers of AVT mRNA producing cells in the magnocellular preoptic area of the hypothalamus than females. Levels of AVT mRNA within these cells in dominant males are also approximately three times female levels whereas the non-aggressive male phenotype has AVT mRNA levels approximately twice female levels. Behavioral sex change is very rapid in this species and is not dependent on the presence of gonads. Conversely, rapid increases in sexual and aggressive behavior during sex change are closely paralleled by approximate fourfold increases in hypothalamic AVT-mRNA levels. The behavioral plasticity shown by bluehead wrasses in response to social environment might be mediated in part by a neuropeptide, AVT, with changes in the gonads and gonadal hormones as the result rather than the cause of behavioral dominance.

Animals↗
PubMed1999

Water disrupts stratum corneum lipid lamellae: damage is similar to surfactants.

Using electron microscopy, we investigated the effect of (i) a dilute surfactant and of water alone on the ultrastructure of stratum corneum lipids in pig skin exposed in vitro at 46 degrees C, and (ii) of water alone on human skin exposed in vivo at ambient temperature. For pig skin, the surfactant sodium dodecyl sulfate disrupts stratum corneum intercellular lamellar bilayers, leading to bilayer delamination and "roll-up" in a water milieu after 1 h, extensive bilayer disruption after 6 h, and nearly complete dissociation of corneocytes after 24 h. Corneodesmosomes show progressive degradation with exposure time. Water alone also disrupts the stratum corneum, but with a slower onset. Alterations in intercellular lamellar bilayers, but not intercellular lamellar bilayer roll-up, are detected after 2 h. Intercellular lamellar bilayer roll-up occurs after 6 h. Extensive dissociation of corneocytes occurs after 24 h of water exposure. Unlike sodium dodecyl sulfate, water exposure results in the formation of amorphous intercellular lipid. Corneodesmosome degradation parallels intercellular lamellar bilayer disruption; calcium appears to offer some protection. Similar disruption of intercellular lamellar bilayers occurs in human skin in vivo at ambient temperature. Our studies show that water can directly disrupt the barrier lipids and are consistent with surfactant-induced intercellular lamellar bilayer disruption being due at least in part to the deleterious action of water. Intercellular lamellar bilayer disruption by water would be expected to enhance permeability and susceptibility to irritants; accordingly, increased attention should be given to the potential dangers of prolonged water contact. For common in vitro procedures, such as skin permeation studies or isolation of stratum corneum sheets, exposure to water should also be minimized.

Animals↗
PubMed1999

Bismuth-mediated disruption of the glycocalyx-cell wall of Helicobacter pylori: ultrastructural evidence for a mechanism of action for bismuth salts.

The mechanism of bismuth's bactericidal activity against Helicobacter pylori was investigated using transmission electron microscopy (TEM) and analytical electron microscopy (AEM); time-kill kinetic methods evaluated the effect of excess divalent cations. TEM analysis of untreated H. pylori revealed a normal morphology. In contrast, H. pylori exposed to bismuth salts had swollen, distorted cells with membrane-cell wall blebbing and a cytoplasm containing electron-dense, sometimes crystalline aggregates. By AEM, swollen cells contained bismuth at the cell periphery, whereas bacillary forms contained cytoplasmic bismuth localizations. Time-kill studies showed that the bactericidal activity of bismuth could be prevented by pretreatment with divalent cations. The effects of bismuth salts on the glycocalyces-cell walls of H. pylori with reversal of bactericidal activity by divalent cations are identical to those produced by other polycationic agents on various gram-negative bacilli. We conclude that disruption of the glycocalyces-cell walls of H. pylori is one mechanism of action for bismuth salts.

Anti-Bacterial Agents↗
PubMed1996

Behavioural sex change in the absence of gonads in a coral reef fish.

It is an axiom of vertebrate behavioural endocrinology that full expression of a male behavioural phenotype depends on testicular influences during development, in adulthood, or both. Sex change in fishes challenges this necessity: behavioural changes are often rapid and greatly precede gonadal changes. However, steroid hormones can have fast actions on the nervous system, so gonadal influences on behavioural sex change cannot be excluded based solely on the speed of these changes. We report that surgical gonad removal does not prevent or discernibly alter female-to-male behavioural sex change in a protogynous coral reef fish. Male behaviour assumption is instead purely dependent on attaining social dominance. This is the first example of a vertebrate fully expressing a male behavioural phenotype without current or previous exposure to a functioning testis or testicular products.

Animals↗
PubMed1996

An 18-year follow-up of primary hepatic carcinoid with carcinoid syndrome.

Primary hepatic carcinoid is extremely rare. Although one of the 18 previously reported cases was accompanied by clinical features of carcinoid syndrome, no patient manifested these features as the presenting complaint, as was true in our case. During the 18 years this patient has been followed, she has been treated with most of the major therapeutic methods, including systemic chemotherapy, hepatic artery chemoembolus injection, extended right hepatic lobectomy, and, eventually, more systemic chemotherapy and octreotide. She continues to be nearly asymptomatic and is still working. We present the results of extensive chemical and hormonal assays, briefly summarize the primary hepatic carcinoids reported previously, and review therapy of this disease.

Adult↗
PubMed1995

Sexual conflict: males with highest mating success convey the lowest fertilization benefits to females.

In natural populations of a coral reef fish (the bluehead wrasse, Thalassoma bifasciatum), males with the highest daily mating success produce the fewest sperm per mating, and this is reflected in significantly lower fertilization rates. The average amount released by males in pair-mating was 3.3 x 10(6) spermatozoa, resulting in a fertilization rate of 96%. Sperm released per spawn declined with increasing mating success, so that females mating with the most successful males had less than 93% of their eggs fertilized. It is unlikely that high mating-success males are physiologically incapable of increasing sperm production, because younger males with different mating strategies have absolutely larger testes and higher daily sperm output. Feeding experiments suggest that high-success males are diverting energy from gamete production to other fitness-enhancing activities such as mate guarding. Females incur the cost of low sperm release by having fewer of their eggs fertilized. There are no obvious compensatory benefits to females from mating with high-success males.

Animals↗
PubMed1995

Corneocytes undergo systematic changes in element concentrations across the human inner stratum corneum.

Using analytical electron microscopy of freeze-dried cryosections, physiologic elements were visualized within individual cells across the human inner stratum corneum. Human corneocytes undergo systematic changes in element composition as they advance through this region. Phosphorus is largely excluded from the stratum corneum, undergoing a precipitous drop in concentration at the granular/stratum corneum interface. The cellular potassium concentration has a profile similar to that of phosphorus but with a slower decline, thus migrating further into the stratum corneum. In contrast, the cellular chloride concentration increases in the innermost corneocyte layer, increases further in the subsequent layer or two (as potassium declines), and then decreases to values comparable to those in the innermost corneocyte. The cellular sodium concentration (per unit volume of tissue) is relatively unaltered in transit across the inner stratum corneum. The initial potassium and chloride movements are oppositely directed and have the appearance of creating an electrical charge imbalance. The position-dependent alterations in corneocyte elemental composition may reflect sequential stages of chemical maturation occurring intracellularly during stratum corneum transit, an example of which is the breakdown of filaggrin that occurs over this same region of the inner stratum corneum.

Chlorine↗
PubMed1994

Octreotide treatment of carcinoid hypertensive crisis.

In the severe crisis of carcinoid syndrome the flush is usually accompanied by hypotension and occasionally shock. Injection of octreotide, the long-acting analog of somatostatin, usually prevents or aborts this vasomotor reaction. A small minority of carcinoid syndrome patients manifest hypertension during their crises and little has been reported in the literature on their management. We present the first case reports of the response of patients with hypertensive carcinoid crisis to treatment with octreotide. The world literature contains reports of 20 prior cases of hypertensive carcinoid crises occurring in association with the stress of surgery and anesthesia. Review of these cases reveals no common feature, other than hypertension, that might clearly distinguish them from the typical hypotensive carcinoid syndrome patient. It is hypothesized that the mechanism of action of octreotide correcting the blood pressure changes in all carcinoid crises is via its known inhibition of vasomotor product release from the tumor and blocking receptors for these substances. We suggest that hypertensive as well as hypotensive carcinoid crises respond to octreotide and that this agent should be considered for prophylactic and emergency use in all carcinoid syndrome patients prior to and during anesthesia and surgery.

Female↗
PubMed1993

Analytical electron microscopy of chlorhexidine-induced tooth stain in humans: direct evidence for metal-induced stain.

Using analytical electron microscopy, we directly tested the hypothesis that transition metals and sulfur are the cause of chlorhexidine-induced tooth stain. Plaque scraped from the teeth of water-treated individuals or chlorhexidine-treated "non-stainers" was non- or lightly-stained and contained low concentrations of sulfur and transition metals. Tooth scrapings from heavily-staining chlorhexidine-treated individuals consisted of distinct unstained and stained regions. The stained regions were organic but were in close proximity to mineralized areas. Enhanced levels of sulfur and transition metals, particularly iron, were found in stained regions, whereas unstained regions contained low sulfur and metal levels similar to the water-treated or non-staining individuals. Excluding decreased mineralization, the major elemental change in heavily-stained plaque was an increase in sulfur, and to a lesser extent, iron and other transition metals. Sulphur and iron levels were directly correlated. Following chlorhexidine treatment with iron supplementation, staining was enhanced, the Fe/S ratio increased, and sulfur and iron remained correlated. These data support the hypothesis that transition metals and sulfur are the cause of chlorhexidine-induced tooth stain. The data are consistent with chlorhexidine treatment altering the incorporation into plaque of a natural sulfur-containing organic component of saliva or bacteria. This natural component appears to readily interact with transition metals, particularly iron, producing stained material.

Chlorhexidine↗
PubMed1988

Electron probe analysis of human skin: determination of the water concentration profile.

The water concentration profile across rapidly frozen human epidermis has been measured using electron probe analysis and analytical electron microscopy. Determinations were made within the cytoplasm of individual cells. From the basal layer, the water content remained relatively constant or decreased slightly across the viable tissue and decreased approximately linearly across the stratum corneum. A considerable discontinuity in water content occurred between these two regions over the stratum corneum-stratum granulosum junction and the last granular cell layer. The dominance of the water profile by a discontinuity suggests water loss is governed by a partitioning process, presumably a partitioning into the lipid domain. A water discontinuity offers important functional advantages in the conservation of substances within the body and in protection from intruding molecules.

Body Water↗
PubMed1988

Electron probe analysis of human skin: element concentration profiles.

Concentration profiles for the major biological inorganic elements Na, P, S, Cl, and K were measured across human skin using electron probe analysis and analytical electron microscopy. Determinations were made within the cytoplasm of individual cells. Uniform element concentrations were present throughout the viable tissue, whereas element profiles in the stratum corneum were considerably diverse. Phosphorus was practically absent from the stratum corneum. Sulfur (per unit volume) continuously increased from the inner to the outer cell layers of the stratum corneum largely as a result of cytoplasmic water loss as cells migrate to the surface. Potassium was essentially excluded from the inner stratum corneum. Very large gradients for K, Na, and Cl occurred from the middle of the stratum corneum to its outer surface; these gradients are likely the result of the inward diffusion of salts from sweat and could play a variety of physiological roles. The paucity of K and P within the inner stratum corneum suggests these important intracellular solutes (and perhaps others, including water) are recycled within the viable tissue, thus providing a virtual nutrient supply immediately underneath the stratum corneum. Alterations in this recirculation could have a regulatory function in the physiology of this tissue.

Chlorine↗