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PubMed2006

[Application of skin soft tissue expansion to reconstruction of scalp soft tissue defect].

OBJECTIVE: To explore an improved method of reconstructing the scalp soft tissue defect with the expanded skin soft tissue and treating and preventing the related complication. METHODS: From October 2002 to June 2005, 32 patients (20 males and 12 females, aged 5-48 years) underwent reconstruction of the scalp soft tissue defects with the expanded scalp soft tissue in the two-stage operation. In the first stage, a tissue expander (cylindrical form, 50-250 ml) was implanted into the skin to achieve a skin soft tissue expansion. After a sufficient skin expansion (8 cm X 5 cm to 25 cm X 23 cm) was made by the routine water effusion for 6-16 weeks, a properly-designed skin flap was taken and transferred to reconstruct the scalp soft tissue defect in the second-stage of the operation. All the scalp defects were left after the resections of the scalp lesions, which ranged in size from 7 cm x 5 cm to 20 cm x 20 cm. RESULTS: After operation, all the 32 patients had their scalp defects repaired and reconstructed well. The expanded skin flaps of all the 32 patients survived except 1 patient who had a necrosis of the distal epidermis of the flap, which healed after the dressings of the wound. The hair grew well and the scars were hidden with a satisfactory appearance. Four patients developed complications (necrosis of the distal flap in 1 patient, hematoma in 1, expander exposure in 1, and wound rupture in 1). CONCLUSION: Reconstruction of the scalp soft tissue defect with the skin soft tissue expansion is an ideal method.

Adolescent↗
PubMed1996

Does visceral adipose tissue differ from subcutaneous adipose tissue in fatty acid content?

OBJECTIVE: To determine whether intra-abdominal adipose tissue differs from subcutaneous adipose tissue in fatty acid content. DESIGN: Cross-sectional study of patients undergoing exploratory laparotomy, with adipose tissue sampling from subcutaneous, omental, mesenteric and retroperitoneal sites. SUBJECTS: Nineteen subjects, 8 men and 11 women, with a mean age of 64 (range 39-80), mean weight 78.9 kg (range 51-157) and mean body mass index of 27.5 (range 19.2-51.4). Fourteen of the 19 were undergoing surgery for colorectal cancer. MEASUREMENTS: Fatty acid content was assessed by gas chromatography and was compared between sites and between patients using general linear modeling. Spearman correlation coefficients were used to assess the association between subcutaneous and visceral adipose tissue. RESULTS: For each of 17 fatty acids analyzed, there was a statistically significant difference in mean fatty acid values across individuals (p < 0.001). For seven of the fatty acids, there was a borderline or significant difference in mean fatty acid values across site, but there was no consistent pattern for one site differing from the others. Subcutaneous adipose tissue fatty acid content was highly correlated to visceral adipose tissue for saturated, unsaturated and trans fatty acids (p < 0.05 for 13 of 17 fatty acids). Variability across individuals was much greater than across site. The total explained variability (R2) for each fatty acid ranged between 49 and 93%, with the vast majority contributed by differences between individuals. CONCLUSION. Fatty acid content of subcutaneous abdominal adipose tissue is a good approximation of visceral adipose tissue. Because variability in fatty acid content is much larger between individuals than within a single individual across sites, subcutaneous abdominal adipose tissue fatty acid content can be used as a distinguishing characteristic among human populations.

Adipose Tissue↗
PubMed1994

Determination of tissue partition coefficients for volatile tissue-reactive chemicals: acrylonitrile and its metabolite 2-cyanoethylene oxide.

Partition coefficients (PCs) are chemical-specific parameters used in physiologically based pharmacokinetic models to describe chemical solubility in tissues. Tissue:air PCs for volatile chemicals can be estimated using vial equilibration techniques in which the chemical concentration in the vial headspace is measured by gas chromatography after equilibrium is reached between the chemical in tissue and air. However, equilibrium would not be expected with tissue-reactive chemicals such as acrylonitrile (ACN) or its epoxide metabolite 2-cyanoethylene oxide (CEO). Active uptake of ACN was observed in rat blood due to reaction with blood sulfhydryl groups, while CEO reacted with all tissues examined (rat blood, muscle, fat, liver, and brain). The active uptake processes were first order as evidenced by a linear decrease in the log of the vial headspace concentrations over time. Linear extrapolation of the log of the apparent PC to zero time, where the contribution of the active uptake process is zero, yielded an estimated PC of 487 for ACN in blood. Equilibrium was achieved with ACN after treatment of blood with diethyl maleate to modify blood sulfhydryl groups, with a PC of 512 +/- 29 (mean +/- SE, n = 14). These PC estimates were verified by direct measurement of ACN concentrations in both the air and the blood (stabilized by acidification). The directly measured ACN blood:air PC was 437 +/- 8 (n = 8), which compared well with the estimated values. Treatment of tissues with diethyl maleate or 2,4-dinitrofluorobenzene did not abolish the active uptake of CEO. However, pretreatment of tissues with CEO itself abolished subsequent CEO uptake. The CEO blood:air PC estimates obtained from zero time extrapolation of four CEO concentrations (1672 +/- 139) and from CEO pretreatment (1658 +/- 137, n = 8) were in good agreement. These data indicate that tissue:air PCs for volatile reactive chemicals can be estimated by extrapolation of a first-order uptake process to zero time or at equilibrium following chemical modification of reactive groups in tissues.

Acrylonitrile↗
PubMed1991

Incorporation of circulating fibronectin into various tissues during sepsis: colocalization with endogenous tissue fibronectin.

We studied the plasma clearance and tissue incorporation of intravenously infused purified human plasma fibronectin into various tissues during a period of acute lung vascular injury induced by lethal postoperative bacteremia in sheep. Lung, liver, spleen, and heart tissue were examined for both endogenous sheep tissue fibronectin as well as the experimentally infused human fibronectin using dual-label immunofluorescence. Awake sheep (n = 4) received a postoperative iv infusion of 5 x 10(9) live Pseudomonas over a 60-min infusion interval. Bacterial challenge was started 2 hr after starting the iv fibronectin infusion of purified human plasma fibronectin (100 mg iv bolus; 4 hr iv at 100 mg/hr). Human fibronectin displayed a biphasic rate of clearance from the plasma with entrance into lymph. Human fibronectin readily incorporated in all tissues studied, including the lung which was the focus of vascular injury. Analysis of tissue sections by dual-label immunofluorescence indicated that the exogenous human fibronectin colocalized with the endogenous sheep fibronectin. Thus, the plasma fibronectin concentration may influence the lung vascular barrier due to its incorporation into the tissue pool of fibronectin. Moreover, the plasma may serve as a reservoir for soluble fibronectin which can enter and colocalize with the insoluble tissue pool of fibronectin in various tissues.

Animals↗
PubMed1984

Antisera raised against eledoisin and kassinin detect immunoreactive material in rat tissue extracts: tissue distribution and chromatographic characterization.

Radioimmunoassays were developed for the tachykinins eledoisin (ELE) and kassinin (KAS) using antisera raised in rabbits. The antisera exhibited low (less than 0.1%) cross-reactivities to substance P (SP) and physalaemin (PHY), but crossreacted (with one exception, antiserum K7) to varying extents with neurokinin A (NKA) and neurokinin B (NKB). In the rat, the tissue distribution of the immunoreactive material detected by antiserum (E7) raised against ELE and by another antiserum (K1) raised against KAS both resembled that previously described for SP. Using the highly KAS-specific antiserum K7, no or only very low levels of immunoreactivity could be detected in extracts of various rat tissues. Gel permeation chromatography and ion-exchange chromatography of tissue extracts indicated that all antisera (except K7) detected the same population of immunoreactive molecules. One of the components was chromatographically indistinguishable from NKA. The tissue distribution of this component also resembled that of SP. Another immunoreactive component co-chromatographed with NKB at cation exchange chromatography. Acid tissue extracts, but not neutral tissue extracts, were found to contain immunoreactive components which appeared more basic than NKA and NKB. The total levels of immunoreactivity were higher in neutral than in acid tissue extracts. However, the ratio between the amounts of immunoreactivities in the two types of extracts varied considerably between tissues, indicating that tachykinin immunoreactive components may be present in different relative proportions in various tissues.

Animals↗
PubMed1992

High-performance liquid chromatographic analysis of amphotericin B in plasma, blood, urine and tissues for pharmacokinetic and tissue distribution studies.

A sensitive and reproducible high-performance liquid chromatographic method was developed to assay ampherotericin B in plasma, blood, urine and various tissue samples. Amphotericin B was isolated from each sample matrix by solid-phase extraction (Bond-Elut). The eluate from Bond-Elut containing amphotericin B was injected onto a reversed-phase C18 column (Waters, mu Bondpak, 10 microns, 300 mm x 3.9 mm I.D.) with a mobile phase of 45% acetonitrile in 2.5 mM Na2EDTA at 1 ml/min. Detection of amphotericin B was by ultraviolet absorption at 382 nm. Blood and tissues were homogenized and extracted with methanol prior to Bond-Elut extraction. The extraction efficiencies of amphotericin B from plasma, blood and tissues were approximately 90, 70 and 75%, respectively. The sensitivity of the assay was less than or equal to 5 ng/ml for plasma, less than or equal to 25 ng/ml for blood, 2.5 ng/ml for urine and 50 ng/g for tissues. The linearity of the assay method was up to 2.5 micrograms/ml for plasma, 5 micrograms/ml for blood, 500 ng/ml for urine and 500 micrograms/g for tissues. The assay was reproducible with an intra-day coefficient of variation (C.V., n = 3) of less than 5% in general for plasma, blood and tissues. The inter-day C.V. of the assay was less than 5% for plasma (n = 5), less than 10% for blood (n = 4) and less than 5% for tissues (n = 3). The overall variability in the urine assay was generally less than 10%. This method has demonstrated significant improvement in the sensitivity and reproducibility in assaying amphotericin B in plasma and especially in blood, urine and tissues. We have employed this assay to compare the pharmacokinetic and tissue distribution profiles of amphotericin B in rats and dogs following administration of Fungizone and ABCD (amphotericin B-cholesteryl sulfate colloidal dispersion), a lipid-based dosage form. In addition, the assay method for plasma and urine samples can also be applied to pharmacokinetics studies of amphotericin B in man.

Amphotericin B↗
PubMed1987

Biochemical investigation of tissue growth: towards definition of "standard" tissue samples.

This paper presents an animal model [the kangaroo], a quantitative anatomical dissection procedure, and a mathematical model [two-phase linear regression] which illustrate that body tissues grow at varying rates relative to each other. An argument is developed that biochemists interested in tissue chemical activity need to be able to sample tissue of known [predicted] growth rate. It is assumed that the ability to select, say muscle tissue samples, from any one animal at a stage of its growth where the individual selected pieces of tissue have known [predicted] low, average and high growth rates would allow comparisons to be made between the sampled tissues that may elucidate the underlying biochemical mechanisms involved in the growth process. It is asserted that to establish standards for tissue samples used in biochemical growth studies, the growth rate of the sampled tissue should be one of the criteria incorporated into the definition of what is "standard" for a tissue sample.

Animals↗
PubMed2000

Tissue engineering in cardiovascular surgery: new approach to develop completely human autologous tissue.

OBJECTIVE: In cardiovascular tissue engineering, three-dimensional scaffolds serve as physical supports and templates for cell attachment and tissue development. Currently used scaffolds are still far from ideal, they are potentially immunogenic and they show toxic degradation and inflammatory reactions. The aim of this study is to develop a new method for a three-dimensional completely autologous human tissue without using any scaffold materials. METHODS: Human aortic tissue is harvested from the ascending aorta in the operation room and worked up to pure human myofibroblasts cultures. These human aortic myofibroblasts cultures (1.5x10(6) cells, passage 3) were seeded into 15-cm culture dishes. Cells were cultured with Dulbecco' s modified Eagle's medium supplemented with 1 mM L-ascorbic acid 2-phosphate for 4 weeks to form myofibroblast sheets. The harvested cell sheets were folded to form four-layer sheets. The folded sheets were then framed up and cultured for another 4 weeks. Tissue development was evaluated by biochemical assay and light and electron microscopy. RESULTS: After 4 weeks of culture in ascorbic acid supplemented medium, myofibroblasts formed thin cell sheets in culture dishes. The cell sheets presented in a multi-layered pattern surrounded by extracellular matrices. Cultured for additional 4 weeks on the frames, the folded sheets further developed into more solid and flexible tissues. Light microscopy documented a structure resembling to a native tissue with confluent extracellular matrix. Under transmission electron microscope, viable cells and confluent bundles of striated mature collagen fibers were observed. Hydroxyproline assays showed significant increase of collagen content after culturing on the frames and were 80.5% of that of natural human pericardium. CONCLUSIONS: Improved cell culture technique may render human aortic myofibroblasts to a native tissue-like structure. A three-dimensional completely autologous human tissue may be further developed on the base of this structure with no show toxic degradation or inflammatory reactions.

Analysis of Variance↗
PubMed2002

Determination of local tissue concentrations of bupivacaine released from biodegradable microspheres and the effect of vasoactive compounds on bupivacaine tissue clearance studied by microdialysis sampling.

PURPOSE: Incorporation of bupivacaine, a short acting local analgesic, into injectable microspheres provides a long acting formulation. Co-incorporation of dexamethasone into the microspheres results in extended activity. The purpose of this study is to compare tissue concentrations of bupivacaine resulting from the two types of microspheres and to determine if the observed sustained tissue concentration of bupivacaine is due to changes in its tissue clearance. METHODS: Microdialysis probes were implanted into rat muscle. Following microsphere injection, bupivacaine tissue concentration was monitored (HPLC-UV), and the tissues histologically examined. The effect of vasoactive compounds on the tissue concentration of bupivacaine, not formulated in microspheres, was monitored. RESULT: Hind muscle histology showed significant granulomatous reactions around the probe and both types of microspheres. A higher, prolonged bupivacaine concentration was observed from microspheres. A higher, prolonged bupivacaine concentration was observed from microspheres with co-incorporated dexamethasone relative to those without dexamethasone. Addition of vasoconstrictors to the perfusate containing bupivacaine resulted in decreased bupivacaine delivery compared to bupivacaine alone, whereas the addition of a vasodilator increased bupivacaine delivery. CONCLUSIONS: The longer lasting effect of microspheres with co-incorporated dexamethasone results from higher, prolonged tissue concentrations of bupivacaine. Dexamethasone, a vasoconstrictor, decreases the clearance rate of bupivacaine from the tissue resulting in a higher, prolonged tissue concentration of bupivacaine.

Animals↗
PubMed2004

Design characteristics for the tissue engineering of cartilaginous tissues.

Tissues like the temporomandibular joint (TMJ) disc and the knee meniscus are often mistakenly viewed as a tantamount to hyaline cartilage, largely due to the absence of a comprehensive understanding of the distinguishing properties of cartilaginous tissues. Because of this confusion, fibrocartilaginous tissue engineering attempts may not be based on suitable experimental designs. Fibrocartilaginous tissues are markedly different than hyaline cartilage; however, the dearth of knowledge related to their cellular and biochemical composition, as well as their biomechanical characteristics, is stunning. Hyaline articular cartilage is exclusively composed of chondrocytes that produce primarily type II collagen, whereas the TMJ disc and the knee meniscus have a mixed cell population of fibroblasts and cells similar to chondrocytes, which predominantly secrete type I collagen. Additionally, fibrocartilaginous tissues have a low glycosaminoglycan content, a low compressive modulus, and a high tensile modulus when compared to hyaline cartilage. Therefore, it is crucial for fibrocartilaginous tissue engineering attempts to be tissue-specific, utilizing the knowledge of the distinct and unique properties of these tissues. At the same time, advances and insights related to the science and engineering aspect of hyaline cartilage regeneration must be carefully considered for the in vitro engineering of fibrocartilaginous tissues.

Animals↗
PubMedDate not supplied

A research-based tumor tissue bank of gynecologic oncology: characteristics of nucleic acids extracted from normal and tumor tissues from different sites.

This article describes a gynecology and pathology-oriented tumor tissue bank that is approaching the research requirements of modern molecular oncology and compared characteristics of nucleic acids extracted from preserved tissues. Through August 2000, 8869 specimens, including fresh neoplastic tissues and normal counterparts, body fluids (ascites, tumor content, and blood), and cervical scrapings, were procured from 1853 patients. DNA and RNA were extracted from a random sampling of normal (n = 50) and tumor (n = 53) tissues from the uterine cervix (n = 47), endometrium (n = 24), and ovary (n = 32). As expected, tumor tissues conferred a higher yield of DNA (1.56 +/- 1.24 versus 0.94 +/- 0.72 microg/mg tissue, P = 0.001) and RNA (5.04 +/- 6.21 versus 2.12 +/- 1.76 microg/ml, P < 0.001) than normal tissues. However, the RNA message abundance, as measured by RNA yield/DNA yield, was not different between tumor and normal tissues. With a similar content of DNA in the endometrium, uterine cervix, and ovary, RNA yield was higher in the endometrium than the others (P = 0.013). In tumors from these three sites, similar yields of DNA and RNA were noted. Overall the yield of DNA remained unchanged from specimens preserved for as long as 7 years, although at this length of storage, RNA yield became lower and variable. This study provides the basic characteristics of nucleic acids derived from normal and tumor tissues and ensures future research utility of these frozen specimens.

Body Fluids↗
PubMed2002

Thyroglobulin in orbital tissues from patients with thyroid-associated ophthalmopathy: predominant localization in fibroadipose tissue.

UNLABELLED: One of the hypotheses that explains the pathogenesis of thyroid-associated ophthalmopathy (TAO) is that thyroglobulin (Tg) is transported through a retrograde lymphatic route to orbital tissues (OT), where it elicits autoimmune damage. In a previous study we demonstrated the presence of intact Tg of thyroid origin in OT from three patients with TAO. The present study was undertaken to investigate this issue further, by increasing the number of patients, by analyzing the distribution of Tg in OT, and by investigating possible relations between the presence of Tg in OT and the clinical features of patients. OT was obtained from seven patients with TAO who underwent decompressive orbitotomy via a transpalpebral approach. Patients were designated P10 to P16. Inflamed palpebral skin, retrobulbar fibroadipose tissue and extraocular muscle surgical samples were collected separately. Tissue extracts were prepared by homogenization and analyzed for the presence of Tg using two different techniques. We first performed immunoprecipitation experiments, in which a rabbit polyclonal anti-Tg antibody was used to capture Tg on protein A and a mouse monoclonal anti-Tg antibody was used to re-veal captured Tg by Western blotting. Intact 330-kd Tg was detected in retrobulbar fibroadipose tissue extracts from three patients (P10, P11, and P16), whereas no Tg was detected in retrobulbar fibroadipose tissue extracts from the remaining four patients. Tg was not detected in the extraocular muscle extracts from all patients studied. In addition, intact 330-kd Tg was found in the inflamed palpebral skin extract from one patient (P10). No Tg was detected in OT extracts from two patients without thyroid or eye disease and in abdominal adipose tissue extracts from two obese patients without thyroid or eye disease. We then searched for Tg by enzyme-linked immunosorbent assay (ELISA), using the same antibodies used for immunoprecipitation. Tg was detected in retrobulbar fibroadipose tissue extracts from four patients (P10, P11, P12, and P16) and in the inflamed palpebral skin extract from patient P10, in amounts ranging from approximately 125 to approximately 400 pg/microg of tissue protein. Again, Tg was not detected in extraocular muscle extracts. A positive gradient between Tg in OT and Tg in the serum was observed in patient P12. Using an ELISA approach, we found that Tg in OT from three TAO patients (P10, P11, and P12) contained thyroxine (T4) residues (mean T(4) CONTENT: 2.42 molecules per molecule of Tg), indicating that Tg had originated in the thyroid. Combining the results obtained in our previous and present study, we found a possible relation between the presence of Tg in OT and the previous treatment with radioiodine. Thus, of the seven patients (3 in the previous and 4 in the present study) in whose OT Tg was found, six had been treated with radioiodine, whereas of the three patients with no Tg in their OT none had been treated with radioiodine. In conclusion, Tg was found in OT extracts from patients with TAO by immunoprecipitation in three of seven cases and by ELISA in four of seven cases. Tg was found in retrobulbar fibroadipose tissue, but not in extraocular muscles. There was a relation between the presence of Tg in OT and the previous treatment with radioiodine. Our results support the hypothesis that Tg may play a role as a coantigen in the pathogenesis of TAO. Further studies are needed to investigate this possibility.

Adipose Tissue↗
PubMed2003

Precursor tissue analogs as a tissue-engineering strategy.

Natural tissues are composed of functionally diverse cell types that are organized in spatially complex arrangements. Organogenesis of complex tissues requires a coordinated sequential transformation process, with individual stages involving time-dependent expression of cell-cell, cell-matrix, and cell-signal interactions in three dimensions. The common theme of temporal-spatial patterning of these cellular interactions is also observed in other physiological processes, such as growth and development, wound healing, and tumor migration. The "precursor tissue analog" (PTA) applies the temporal-spatial patterning theme to tissue engineering. The goal of PTA in tissue engineering is not to fabricate the final transplantable tissue but rather to guide the dynamic organization, maturation, and remodeling leading to the formation of normal and functional tissues. We describe the critical design principles of PTA. First, structural, mechanical, and physiological requirements of the PTA as a temporary scaffold must be met by a fabrication method with flexibility. The fabrication potential incorporating biological materials such as living cells and plasmid DNA has been addressed. Second, the PTA concept is considered suitable for future tissue engineering in light of the use of undifferentiated stem cells, and may possess a capability to guide stem cells toward diverse differentiation characteristics in situ. To this end, the behavior of the engineered cell and tissue must be monitored in detail. The development of a practical phenotype monitoring system such as a DNA microarray may be integral to the fabrication strategies of PTA. Third, the microtopographical and microenvironmental control on the liquid-solid interaction may lead to a critical design for PTA to provide soluble factors, nutrients, and gases to the cells embedded within the scaffold. We suggest that the level set numerical simulation method may be utilized to engineer the consistent circulation of bioactive liquid throughout the PTA microenvironment.

Animals↗
PubMed1977

The effects of tissue processing on markers for T and B cells from solid tissues.

Suspensions of lymphoid cells from tissues have been used for the determination of the quantitative relationship between the T and B cell populations. The distribution of the lymphocytes within a given tissue, however, cannot be demonstrated once such a suspension has been prepared. Various methods of characterizing lymphocytes within tissues were evaluated. The method of tissue preparation can alter the capability of detecting the lymphocyte markers. Fluorescein-labeled anti-immunoglobulin sera reacted equally well with lymphocytes in tissue regardless of the method of tissue preparation. Complement-coated sheep erythrocytes were less effective in detecting lymphocyte markers in tissue sections than in cell suspensions. Quantitative assays of lymphocytes could be done in suspensions only. Unaltered sheep erythrocytes did not bind to T lymphocytes in tissue. T lymphocytes could be identified in tissue sections, however, by the use of anti-human T cell serum.

Animals↗
PubMed1983

The in vivo tissue disposition and in vitro target-tissue metabolism of the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone in Syrian golden hamsters.

The tobacco-specific N-nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), labeled with 14C in the carbonyl group, was given i.v. or s.c. to Syrian golden hamsters. Whole-body autoradiography indicated that NNK is distributed evenly in the intra- and extracellular tissue water and reaches all tissues. An accumulation of radioactivity was observed in the stomach contents, probably due to the basicity of NNK and its metabolites, which are trapped in the acid gastric juice. The basicity of these compounds is also responsible for their binding to the eye melanin. A high level of tissue-bound metabolites occurred in the mucosa of the ethmoturbinates, in the lungs and in the trachea, which are the targets for the carcinogenicity of NNK in the hamster. In the lungs and the trachea, the radioactivity was confined to the epithelium of the air-conducting ways (the bronchial, bronchiolar and tracheal epithelium). Microautoradiography of the nasal olfactory mucosa showed the highest labeling over Bowman's glands in the lamina propria mucosae. The liver was the only non-target tissue which retained detectable tissue-bound metabolites in vivo. Levels of in vitro degradation of NNK to tissue bound and unbound metabolites were the highest in the nasal mucosa. This tissue as well as the other target tissues - the lung and the trachea - produced considerable amounts of metabolites which are probably derived from alpha-carbon hydroxylations of NNK. In the liver, on the other hand, the main metabolite was a reduction product of NNK. Our results demonstrate that tumorigenesis is correlated with NNK metabolism and binding in the target tissues and support the hypothesis that alpha-carbon hydroxylation is the mechanism of activation of NNK.

Animals↗
PubMedDate not supplied

A review of normal tissue hydrogen NMR relaxation times and relaxation mechanisms from 1-100 MHz: dependence on tissue type, NMR frequency, temperature, species, excision, and age.

The longitudinal (T1) and transverse (T2) hydrogen (1H) nuclear magnetic resonance (NMR) relaxation times of normal human and animal tissue in the frequency range 1-100 MHz are compiled and reviewed as a function of tissue type, NMR frequency, temperature, species, in vivo versus in vitro status, time after excision, and age. The dominant observed factors affecting T1 are tissue type and NMR frequency (V). All tissue frequency dispersions can be fitted to the simple expression T1 = AVB in the range 1-100 MHz, with A and B tissue-dependent constants. This equation provides as good or better fit to the data as previous more complex formulas. T2 is found to be multicomponent, essentially independent of NMR frequency, and dependent mainly on tissue type. Mean and raw values of T1 and T2 for each tissue are tabulated and/or plotted versus frequency and the fitting parameters A, B and the standard deviations determined to establish the normal range of relaxation times applicable to NMR imaging. The mechanisms for tissue NMR relaxation are reviewed with reference to the fast exchange two state (FETS) model of water in biological systems, and an overview of the dynamic state of water and macromolecular hydrogen compatible with the frequency, temperature, and multicomponent data is postulated. This suggests that 1H tissue T1 is determined predominantly by intermolecular (possibly rotational) interactions between macromolecules and a single bound hydration layer, and the T2 is governed mainly by exchange diffusion of water between the bound layer and a free water phase. Deficiencies in measurement techniques are identified as major sources of data irreproducibility.

Adipose Tissue↗
PubMed1983

Studies of the nuclear 5 alpha-reductase of human prostatic tissue: comparison of enzyme activities in hyperplastic, malignant, and normal tissues.

The nuclear conversion of testosterone (T) to dihydrotestosterone (DHT) was compared in hyperplastic (n = 40), malignant (n = 20), and normal (n = 3) prostatic tissues. Standard assay conditions were 2 microM testosterone, 2.0 mM EDTA, 1.0 mM NADPH, and the nuclear fraction equivalent to 200 mg of prostatic tissue, in 0.1 M N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid buffer (pH 7.4). The Km values were 0.6, 0.5, and 0.3 microM, respectively, for the enzymes in hyperplastic, malignant, and normal tissues. The Vmax values were 42 +/- 17, 4.2 +/- 1.8, and 3.9 +/- 0.9 pmol/mg protein per 30 min of incubation, respectively, for the hyperplastic, malignant, and normal tissues. When DHT formation was measured at T concentrations equivalent to reported endogenous levels, it was found that enzyme activity in the hyperplastic tissue was still greater than that in the other two tissues. The enzyme in the malignant prostate was less efficient than the enzyme in normal tissue in converting T to DHT. These results would suggest that differences in the conversion of T to DHT may explain, at least in part, the higher DHT levels seen in hyperplastic tissue than in either the normal or the malignant prostate and the higher T levels seen in the malignant prostate than in the other two tissues.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2002

Analysis of the molecular quality of human tissues: an experience from the Cooperative Human Tissue Network.

The scientific usefulness of the data obtained from tissue analysis is related to specimen quality, which may be affected by conditions that may contribute to the degradation of the specimen before processing and analysis. We determined the usability of nucleic acids extracted from banked human tissues for further molecular analyses. We assayed 151 tissue specimens, storedfor various times at 4 divisions of the Cooperative Human Tissue Network, National Cancer Institute, Bethesda, MD, for DNA and RNA degradation. Simple electrophoresis, polymerase chain reaction (PCR), reverse-transcriptase (RT)-PCR, and Northern blot analysis were compared to determine the optimal quality control procedure. In addition, a time course degradation procedure was performed on human lung tissue. Gel electrophoresis was as informative as PCR, RT-PCR, and Northern blot analysis in determining the molecular usefulness of the human tissues. Overall, 80% of the stored human tissues had good-quality DNA, and 60% had good-quality RNA. Electrophoresis procedures for DNA and RNA offer a quick and valuable measure of the molecular quality of stored human tissues. The DNA and RNA degradation of one tissue type (lung) was stable for both nucleic acids for up to 5 hours after excision.

Blotting, Northern↗