Search PubMed⌕ Search

Biomedical subjects

C R Taylor

Publications and source records attributed to C R Taylor.

At least 127 records · Page 7Linked to original sources
PubMed1993

Treatment of benign pigmented epidermal lesions by Q-switched ruby laser.

BACKGROUND: Disorders of cutaneous pigmentation are a common problem, which can cause substantial cosmetic morbidity. Traditional treatments are often ineffective and sometimes associated with further hyperpigmentation, hypopigmentation, or scarring. Because the Q-switched ruby laser has proven useful for the treatment of tattoos and, in a small number of cases, benign disorders of the epidermal melanin, we decided to apply this modality systematically to additional benign pigmented lesions. METHODS: Thirty-four benign pigmented epidermal lesions including lentigines, café-au-lait macules, and nevi spili in nine white patients were exposed to single pulses of a Q-switched ruby laser (694 nm, 40 ns pulse duration) at 4.5 and/or 7.5 J/cm2. RESULTS: After one treatment, substantial clearing occurred at each fluence in all lentigines and café-au-lait macules. Initial improvement was achieved in a small nevus spilus after two treatments at 4.5 J/cm2 and a larger nevus spilus after one treatment at 7.5 J/cm2 with complete removal of the junctional or compound nevi portion but no improvement in the café-au-lait portion. Complete return of the background pigment was observed by 1 year. There was no scarring. Immediately after treatment, histology revealed vacuolization of keratinocytes and melanocytes, and occasional subepidermal blisters. CONCLUSIONS: These findings show that while the Q-switched ruby laser may not be entirely useful for treating nevi spili, it does provide an effective treatment for lentigines and café-au-lait macules.

Adolescent↗
PubMed1993

Mismatch between lipid mobilization and oxidation: glycerol kinetics in running African goats.

Glycerol kinetics and total fatty acid (FA) oxidation of trained African pygmy goats were measured by continuous infusion of [2-3H]glycerol and indirect calorimetry during treadmill exercise at 40, 60, and 85% maximal O2 consumption (VO2max). Our main goals were 1) to determine whether rates of FA mobilization and utilization are eventually matched as exercise intensity increases, thereby minimizing reesterification to supply more FA to working muscles, and 2) to test the hypothesis that lipolytic rate is proportional to aerobic capacity by comparing low-aerobic goats with published values from highly aerobic dogs and humans. Mean rate of glycerol release in the circulation (Ra glycerol) was 3.83 +/- 0.11 at rest, 7.69 +/- 0.88 at 40% VO2max, reached a maximum of 15.32 +/- 0.95 at 60% VO2max, and returned to 10.53 +/- 0.76 mumol.kg-1 x min-1 at 85% VO2max. Lipolytic rate did not match total FA oxidation, implying that Ra glycerol cannot be used as an index of FA utilization, even during intense exercise. A large fraction of total FA released by lipolysis was reesterified at 60 and 85% VO2max, showing that FA mobilization does not limit whole animal FA oxidation at these intensities. Comparing goat, dog, and human responses reveals that mammalian lipolytic rate is scaled with aerobic capacity. High- and low-aerobic species exercising at the same %VO2max mobilize FA in exact proportion with their metabolic rate, suggesting that the relative contribution of FA to total energy provision is independent of VO2max.

Animals↗
PubMed1993

Antigen retrieval technique utilizing citrate buffer or urea solution for immunohistochemical demonstration of androgen receptor in formalin-fixed paraffin sections.

We developed a staining protocol for demonstration of androgen receptor (AR) in formalin-fixed, paraffin-embedded tissue sections. The method is based on the antigen retrieval microwave (MW) heating technique. Results are compared with different types of enzyme digestion pre-treatments. The strongest immunostaining signal and clearest background were obtained by MW heating of dewaxed paraffin sections in 5% urea or citrate buffer solution (pH 6); pure distilled water gave less consistent results. Enzymatic digestion with pepsin (0.05% in 2 N HCl) for 30 min at room temperature, or trypsin followed by pronase, or pronase digestion alone, also produced enhanced staining of AR in some cases, but there was more nonspecific background, and specific reactivity was less intense. The antigen retrieval MW method can be used to demonstrate AR epitope in prostate tissue after fixation in formalin for as long as 7 days. AR immunolocalization was also compared in frozen and paraffin sections processed from the same specimen of prostate carcinoma tissue and was found to be qualitatively and quantitatively similar. This study also provided new information concerning the basic principles of the antigen retrieval MW method that may be helpful in further development of this technique.

Antigens, Neoplasm↗
PubMed1993

Glycogen loss in rat muscles during locomotion on different inclines.

Running downhill causes structural damage in deep slow-twitch extensor muscles of the limbs. Both mechanical and metabolic hypotheses have been proposed to explain the damage. The purpose of this study was to use measurements of glycogen loss in the muscles and metabolic rates of rats running on the level and up and down 16 degrees inclines at 26 m min-1 to try to distinguish between these hypotheses. Glycogen loss in the soleus and medial head to the triceps brachii muscles during running on the three inclines was proportional to whole-animal oxygen consumption, indicating that there were no unusual metabolic demands on these muscles during the downhill exercise. The minimum area of these muscles showing glycogen loss was smaller during downhill than during uphill running. Average forces in the muscles are similar during locomotion on different inclines at the same speed, suggesting that stresses in the active motor units were greater during downhill running. Thus, the results are more consistent with a mechanical than with a metabolic etiology for the muscle injury resulting from downhill running.

Animals↗
PubMed1993

Immunohistochemical study of intermediate filament proteins on routinely processed, celloidin-embedded human temporal bone sections by using a new technique for antigen retrieval.

Although immunohistochemical studies of intermediate filament proteins have been carried out on temporal bone sections by using modified fixation/embedding techniques to preserve antigenicity, there have been no light microscopic studies concerning immunohistochemical staining on routinely formalin-fixed celloidin-embedded human temporal bone sections. A method for immunostaining routinely processed celloidin-embedded tissues would be extremely valuable in that it would permit study of the extensive collections of formalin-celloidin temporal bone specimens that exist in major centers of otopathologic research. Recently, we have developed a new technique which can be used to retrieve the antigenicity masked by formalin fixation and decalcification. This method requires immersing slides for 30 min at room temperature in a solution of saturated sodium hydroxide in methanol before immunostaining. Using this method, 45 celloidin-embedded human temporal bone sections were stained with monoclonal antibodies to keratin, vimentin, neurofilament, glial fibrillary acidic protein and desmin as primary antibodies using a sensitive streptavidin-biotin procedure. The results obtained by using this technique are at least equivalent to those obtained with modified fixatives, cryosections or immuno-electron microscopy. This new method may provide a useful approach for studying routinely processed, celloidin-embedded human temporal bone sections and open a new field in immuno-otopathology.

Adult↗
PubMed1993

Differential S100 beta expression in choroidal and skin melanomas: quantitation by the polymerase chain reaction.

PURPOSE: S100 beta, a member of a calcium-binding protein family (S100s), is an important clinical marker for skin melanoma. In contrast, uveal melanomas appeared to express S100 beta protein less frequently and to a lesser degree. This study was performed to verify and extend this finding to the mRNA level. METHODS: A quantitative polymerase chain reaction (PCR)-based method was used. A ratio, comparing the S100 beta PCR fragment to that of beta-actin (an internal reference gene), was generated to compare S100 beta mRNA expression among samples. RESULTS: The ratios for skin melanomas (1.2 to 3.9; three tissues and two cell lines) were significantly higher than that for choroidal melanomas (0.1 to 0.63; seven of eight primary tumors and four of four cell lines). Only one choroidal melanoma biopsy had a ratio greater than 1. The PCR products from choroidal melanoma were identical in size and sequence to the S100 beta, as determined by gel electrophoresis and RNA conformational polymorphism. Because the ratios were also low in choroidal melanoma cell lines, the S100 beta phenotype appears to be genetically stable. CONCLUSION: S100 beta is differentially expressed at the RNA and protein levels by skin and choroidal melanomas, which are derived from distinct populations of melanocytes. However, choroidal melanomas expressing little or no S100 beta were significantly stained by antiserum specific for the S100 protein family. Taken together, these data suggest that choroidal melanocytes express another, perhaps even novel, S100 protein(s).

Actins↗
PubMed1992

Estimating transit time for capillary blood in selected muscles of exercising animals.

The mean minimal capillary transit time was estimated in muscles of various animals using a combination of physiological and morphometric methods. Radioactive microspheres were injected intravascularly in various animals running on a treadmill at maximum oxygen consumption rate (VO2,max) to label blood flow to individual muscles. The muscles were then removed and preserved by standard methods for electron microscopy. The volume density of mitochondria was measured to assess muscle oxidative capacity. Capillary densities in muscle cross-sections, capillary diameters and tortuosities were incorporated into an estimate of capillary volume per unit muscle mass. Mean capillary transit time (tc) in the exercising muscles was estimated by dividing mass-specific capillary volume by mass-specific blood flow. Estimates of tc ranged from values near 1 s in horse heart and thigh muscles to 0.2 s in duck gastrocnemius. The relationship between muscle blood flow and tc was hyperbolic. The experimental data indicate a limiting value of 0.2 s for transit times at very high blood flows. There was no correlation between tc and body-mass-specific VO2,max.

Animals↗
PubMed1992

Variations in function and design: testing symmorphosis in the respiratory system.

We explore the question of whether and to what extent the large variation in energy requirements observed among mammals is related to variations in the design of the respiratory system, from the lung to the mitochondria in muscle cells. Resting metabolic rate is determined by body size (allometric variation). Maximal rates of O2 consumption (VO2 max) also vary in a regular manner with body size, but adaptive variation allows some species to achieve much higher values than others of the same body size. We, therefore, consider adaptive variation as modulation of structures and functions above those determined by allometric variation. A model is presented that separates functional and design parameters at four steps of the respiratory cascade: the pulmonary gas exchanger, heart and blood, microvasculature, and mitochondria. The variations observed in these parameters are analyzed with respect to those in energy demand and are discussed in relation to the hypothesis of symmorphosis. We conclude that the design of the internal steps of the respiratory system (mitochondria, capillaries, blood, and heart) is matched to functional demand, whereas the lung maintains a variable excess of morphometric diffusing capacity which may be related to the facts that the lung has limited malleability and that it forms the interface with the environment.

Animals↗
PubMed1992

Monocytoid B-cell lymphomas: an assessment of diagnostic criteria and a perspective on histogenesis.

To determine which morphologic criteria are most useful in distinguishing reactive from malignant monocytoid B cells (MBCs), we compared 16 monoclonal cases (11 nodal, five extranodal) of monocytoid B-cell lymphoma (MBCL) with 12 cases of various reactive diseases in which MBCs were polyclonal. The results of our study showed that in MBCL the MBC component was the predominant architectural finding and that there was confluence of MBCs in all but one case. In contrast, the MBC component did not predominate in the reactive group (P less than .000001) and focal confluence was seen in only one case. A cytologic comparison showed that in MBCL areas there were more large transformed (prominent nucleolated) MBCs (P = .003), a higher mitotic rate (P = .03), and more nuclear irregularities (P = .007) than were present in the reactive group. In addition, evolution to an aggressive histologic type was found in four cases of MBCL. Our results also revealed concomitant multiple, monoclonal, morphologically distinct populations in other compartments (follicular center cells in seven, mantle cells in five, small lymphocytes in five, and plasma cells in 11). These unique findings can be reconciled by postulating (1) that the simultaneous presence of these diverse cytologic types represents morphologic expressions of a B cell whose population is in different phases of its cell cycle and/or its evolution or (2) that the histogenesis of MBCL is possibly from a nodal pluripotent B-stem cell that can differentiate directly into these various cytologic types.

Adult↗
PubMed1992

Computed tomography in the evaluation of the portal venous system.

Computed tomography has widespread clinical application in the evaluation of the portal venous system, even though quantitative methods are impractical due to the inability to measure portal flow discrete from hepatic arterial flow, morbidity associated with the use of large volumes of iodinated contrast, and technical limitations. This represents a major disadvantage compared to Doppler ultrasound and magnetic resonance angiography. Qualitative applications include evaluation of portal vein patency, diagnosis of portal vein thrombosis, underlying inflammatory or neoplastic conditions, and evaluation of surgically created portosystemic shunts and collateral flow. Diagnostic criteria for portal venous thrombosis include nonopacification of the central portion of the portal vein, peripheral enhancement of the vein, and irregular periportal hepatic parenchymal enhancement. However, misdiagnosis is common, occurring in 16% of cases analyzed in one limited series, and periportal vein enhancement is now recognized as a nonspecific finding associated with underlying endothelial injury. Cavernous transformation of the portal vein and neoplastic invasion of the portal system are more reliably recognized. Computed tomography arterial portography demonstrates collateral pathways and arteriovenous shunts. Computed tomography has a sensitivity of 85% in detection of esophageal varices compared to endoscopy, but has the advantage of demonstrating splenorenal, gastrorenal, peripancreatic, pericholecystic, retroperitoneal and omental collateral vessels, and spontaneous large portosystemic shunts, with greater sensitivity than angiography. Computed tomography combined with Doppler ultrasound angiography remains popular, despite a lack of large-scale prospective efficacy studies demonstrating diagnostic superiority over other imaging techniques, largely because of its accessibility, and its detailed axial anatomic images providing an overview of multiple organ systems, and patency of major vessels.

Collateral Circulation↗
PubMed1992

Magnetic resonance imaging in the evaluation of the portal venous system.

Magnetic resonance (MR) imaging is used in assessing the portal venous system through qualitative and quantitative methods. Magnetic resonance angiography can be performed using time-of-flight or phase-contrast techniques. Time-of-flight techniques (which use gradient echo images to display bright blood or spin echo images to display black blood) are relatively standardized and commercially available. These techniques are used to display liver morphology, portal vein patency, portal venous collaterals, and surgically created portosystemic shunts. Magnetic resonance is equivalent to angiography in the detection of varices, according to a preliminary study. Time-of-flight flow imaging using gradient echo techniques (in which a thrombus appears as absence of bright signal in the portal vein) and spin-echo techniques (where thrombus appears as a bright signal) can become combined to increase specificity for diagnosis of portal vein thrombosis. Phase-contrast techniques provide flow information based on phase shifts induced by flow through magnetic gradients. Phase-contrast angiography is less widely available than time-of-flight angiography. However, phase-contrast methods allow imaging of very slow flow that is not possible using time-of-flight methods. Quantitation of flow is possible, both with time-of-flight techniques using bolus tracking and with phase-contrast techniques using quantitative measurement of phase shifts. Calculations of flow velocity correlate well with Doppler ultrasound estimations, MR flow quantitation does not, at present, rival ultrasound in terms of cost or availability. However, MR is not limited by obesity or overlying bowel gas which can prevent adequate ultrasound evaluation.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1992

O2 delivery at VO2max and oxidative capacity in muscles of standardbred horses.

The purpose of this study was to describe the relationships between 16 physiological, biochemical, and morphological variables presumed to relate to the oxidative capacity in quadriceps muscles or muscle parts in Standardbred horses. The variables included O2 delivery (blood flow) and mean capillary transit time (MTT) during treadmill locomotion at whole animal maximal O2 consumption (VO2max, 134 +/- 2 ml.min-1 x kg-1), capillary density and capillary-to-fiber ratio, myoglobin concentration, oxidative enzyme activities, glycolytic enzyme activities, fiber type populations, and fiber size. These components of muscle metabolic capacity were found to be interrelated to varying degrees using correlation matrix analysis, with lactate dehydrogenase activity showing the most significant correlations (n = 14) with other variables. Most of the "oxidative" variables occurred in the highest quantities in the deepest muscle of the group (vastus intermedius) and in the deepest parts of the other quadriceps muscles where the highest proportions of type I fibers were localized. The highest blood flow measured with microspheres in the muscle group during exercise was in vastus intermedius muscle (145 ml.min-1 x 100 g-1), and the lowest was in the superficial part of rectus femoris muscle (32 ml.min-1 x 100 g-1). Average muscle blood flow during exercise at whole animal VO2max was 116 ml.min-1 x 100 g-1. Because skeletal muscle comprised 43% of total body mass (453 +/- 34 kg), total muscle blood flow was estimated at 226 l/min, which was approximately 78% of total cardiac output (288 l/min).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

A technique for retrieving antigens in formalin-fixed, routinely acid-decalcified, celloidin-embedded human temporal bone sections for immunohistochemistry.

The application of immunohistochemistry to routinely decalcified, celloidin-embedded human temporal bone sections has been hampered because of antigen loss during processing of the specimens. To our knowledge, there has been no published report to date describing immunohistochemical staining of such tissues suitable for examination by light microscopy. Here we report a novel antigen retrieval technique which can be successfully used to stain a variety of antigens in routinely formalin-fixed, trichloroacetic acid-decalcified, celloidin-embedded human temporal bone sections. The new procedure reported here for decalcified human temporal bone tissues simply requires immersing slides for 30 min at room temperature in an antigen retrieval solution. A total of 60 decalcified, celloidin-embedded human temporal bone tissues were tested with monoclonal antibodies (MAb) to 15 different antigens. Of these, 12 MAb showed definite positive staining, while three were negative. This technique may prove very useful in studying the expression of various antigens by immunohistochemistry in formalin-fixed, acid-decalcified, celloidin-embedded tissues.

Antibodies, Monoclonal↗
PubMed1992

Quality assurance and standardization in immunohistochemistry. A proposal for the annual meeting of the Biological Stain Commission, June, 1991.

Quality assurance, quality control, proficiency testing, reagent documentation and validation are standard parts of everyday practice in clinical laboratories throughout the United States. Immunohistochemical stains employ reagents and principles in common with immunoenzyme methods utilized in the clinical laboratory. However, immunohistochemistry has not routinely been subjected to similar standardization and quality assurance procedures that manufacturers and pathologists alike have applied to essentially the same techniques in the clinical laboratory environment. The current proposal was invited by the Biological Stain Commission with the charge of incorporating the findings of previous workshops on quality control in immunohistochemistry into a practical design for implementation. The status of quality assurance, quality control and standardization in immunohistochemistry is reviewed and a phased strategy for implementation is proposed.

Immunohistochemistry↗
PubMed1991

The concept of symmorphosis: a testable hypothesis of structure-function relationship.

The hypothesis that, in biological organisms, structural design is matched to functional demand is difficult to test because it is largely based on anecdotal evidence suggesting economic design. The hypothesis of symmorphosis postulates a quantitative match of design and function parameters within a defined functional system; because of its stringency it is refutable and can, therefore, be subjected to empirical test, for example, by assessing whether the structures that support the pathway for oxygen from the lung to the consumer in muscle cells are quantitatively adjusted to the limit of functional performance of the respiratory system. The study of allometric and adaptive variation leads to the conclusion that the hypothesis of symmorphosis is acceptable for all internal compartments of the respiratory system (blood, heart, muscle capillaries, and mitochondria), whereas it must be refuted for the lung that forms the interface to the environment.

Adaptation, Physiological↗