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In vivo tissue-engineered small-caliber arterial graft prosthesis consisting of autologous tissue (biotube).

In this study, vascular-like tubular tissues called biotubes, consisting of autologous tissues, were prepared using in vivo tissue engineering. Their mechanical properties were evaluated for application as a small-caliber artificial vascular prosthesis. The biotubes were prepared by embedding six kinds of polymeric rods [poly(ethylene) (PE), poly(fluoroacetate) (PFA), poly(methyl methacrylate) (PMMA), segmented poly(urethane) (PU), poly(vinyl chloride) (PVC), and silicone (Si)] as a mold in six subcutaneous pouches in the dorsal skin of New Zealand White rabbits. For rods apart from PFA, biotubes were constructed after 1 month of implantation by encapsulation around the polymeric implants. The wall thickness of the biotubes ranged from about 50 to 200 microm depending on the implant material and were in the order PFA < PVC < PMMA < PU < PE. As for PE, PMMA, and PVC, the thickness increased after 3 months of implantation and ranged from 1.5-to 2-fold. None of the biotubes were ruptured when a hydrostatic pressure was gradually applied to their lumen up to 200 mmHg. The relationship between the intraluminal pressure and the external diameter, which was highly reproducible, showed a "J"-shaped curve similar to the native artery. The tissue mostly consisted of collagen-rich extracellular matrices and fibroblasts. Generally, the tissue was relatively firm and inelastic for Si and soft for PMMA. For PMMA, PE, and PVC the stiffness parameter (beta value; one of the indexes for compliance) of the biotubes obtained was similar to those of the human coronary, femoral, and carotid arteries, respectively. Biotubes, which possess the ability for wide adjustments in their matrices, mechanics, shape, and luminal surface design, can be applied for use as small-caliber blood vessels and are an ideal implant because they avoid immunological rejection.

Animals↗

Activated primary and memory CD8 T cells migrate to nonlymphoid tissues regardless of site of activation or tissue of origin.

Following activation within secondary lymphoid tissue, CD8 T cells must migrate to targets, such as infected self tissue, allografts, and tumors, to mediate contact-dependent effector functions. To test whether the pattern of migration of activated CD8 T cells was dependent on the site of Ag encounter, we examined the distribution of mouse Ag-specific CD8 T cells following local challenges. Our findings indicated that activated CD8 T cells migrated pervasively to all nonlymphoid organs irrespective of the site of initial Ag engagement. Using an adoptive transfer system, migration of nonlymphoid memory cells was also examined. Although some limited preference for the tissue of origin was noted, transferred CD8 memory T cells from various nonlymphoid tissues migrated promiscuously, except to the intestinal mucosa, supporting the concept that distinct memory pools may exist. However, regardless of the tissue of origin, reactivation of transferred memory cells resulted in widespread dissemination of new effector cells. These data indicated that recently activated primary or memory CD8 T cells were transiently endowed with the ability to traffic to all nonlymphoid organs, while memory cell trafficking was more restricted. These observations will help refine our understanding of effector and memory CD8 T cell migration patterns.

Adoptive Transfer↗

Immunohistochemical detection of C-100 hepatitis C virus antigen in formaldehyde-fixed paraffin-embedded liver tissue. Correlation with serum, tissue and in situ RT-PCR results.

We localized HCV C-100 protein in liver biopsies of 15 patients with chronic hepatitis C using immunohistochemistry. The results were compared to serum, tissue extract analysis of HCV RNA and in situ RT-PCR described in a previous study. HCV was detected in 80% of the sera tested, in 40% of the tissue extracts and in 80% and 60% of the tissue sections tested by immunohistochemistry and in situ RT-PCR respectively. Compared to the serum positive cases, 83% and 67% of the cases were respectively positive with immunohistochemistry and in situ RT-PCR and 41% were positive with tissue extract detection. Compared to the tissue extract positive cases, 25% and 50% of the cases were respectively positive with immunohistochemistry and in situ RT-PCR. Finally, 75% of the cases positive by immunohistochemistry were also positive by in situ RT-PCR. These results underline the complementarity of the different methods for the precise diagnosis of hepatitis C.

Formaldehyde↗

[Tissue plasminogen activator antigen (t-PA Ag) and tissue plasminogen activator inhibitor (PAI-1) in the course of hemodialysis in patients with chronic renal failure].

In 10 patients with chronic renal insufficiency we are tissue plasminogen activator antigen (t-PA Ag), tissue plasminogen activator inhibitor (PAI-1) and euglobulin lysis time (ELT) designed. This parameters are just before hemodialysis, in 60 minutes and 240 minutes after beginning of dialysis studied. In 60 minutes after the beginning of hemodialysis significant increased tissue plasminogen activator inhibitor antigen, decreased tissue plasminogen activator inhibitor activity and prolonged euglobulin lysis time. The observed increase in plasma t-PA antigen levels during hemodialysis is due to effects of extracorporal circulation on the fibrinolytic system. T-PA release and consequent consumption of tissue plasminogen activator inhibitor due to enhanced fibrinolytic activity during hemodialysis.

Adult↗

A tissue engineered cell-occlusive device for hard tissue regeneration--a preliminary report.

Tissue engineering is an emerging discipline that applies engineering principles to create devices for the study, restoration, modification, and assembly of functional tissues and organs from native or synthetic sources. In the field of guided bone regeneration (GBR), cellular matter engineering has been applied, more or less successfully, to the development of biodegradable and bioresorbable devices with chemical, physical, or mechanical properties, structure, or form that permit active tissue integration with desirable cell types and tissue components. The employment of synthetic and naturally occurring polymers as well as sophisticated manufacturing technologies allow the tissue engineering of matrix configurations so that the biophysical limitations of mass transfer can be satisfied. The configuration of such a hybrid matrix can also be manipulated to vary the surface area available for cell attachment, as well as to optimize the exposure of the attached cells to nutrients. A biodegradable and bioresorbable device made of synthetic and natural polymers was engineered specifically for GBR procedures. The degradation and resorption kinetics as well as the mechanical properties give the device the potential to function as a carrier for bone growth factors. This innovative device was applied as a GBR membrane in a clinical investigation in seven patients.

Absorbable Implants↗

[Tissue-specific depression of DNA synthesis by calcium salt-free liver and lung extracts that are able to increase the stability of cell linkage in the tissue].

The macromolecular fraction of Ca-free salt extracts (Ca-FSE) removed from lungs and liver of adult rats, mice and fishes inhibits DNA synthesis in the embryonic tissue. The effect of Ca-FSE is tissue-specific rather than species-specific. Ca-FSE was earlier reported to increase with the same specificity the tissue stability to mechanical disruption. A concept is proposed that the tissue-specific adhesive factor may play the role of G1-chalone in epithelial tissue.

Animals↗

Effect of nitric oxide donors on isoprenaline-induced lipolysis in rat epididymal adipose tissue: studies in isolated adipose tissues and immobilized perfused adipocytes.

The present investigation was directed to study the effect of in vitro or ex vivo NO donors, sodium nitroprusside and molsidomine, using isolated sliced adipose tissue or in the form of immobilized and perfused adipocytes on the basal and isoprenaline-stimulated lipolysis. The results demonstrated that 1) in vitro application of sodium nitroprusside to perfused adipocytes or molsidomine to sliced adipose tissues affects isoprenaline-induced lipolysis in two ways, an increase in lipolysis at low isoprenaline concentrations (which means the sensitization of adipose tissues to adrenergic effect by NO) and decreased adrenergic agonist-stimulated lipolysis at higher concentration of isoprenaline (a decrease in the maximum lipolytic effect of isoprenaline), 2) low concentrations of molsidomine alone induced lipolysis from adipose tissue which attained more than 60% of that by isoprenaline (pD2 value for molsidomine = 11.2, while pD2 for isoprenaline = 8.17) while sodium nitroprusside did not affect the basal lipolysis significantly, 3) in vivo administration of molsidomine for 2 days reduced the maximum lipolytic effect of isoprenaline and (only non-significantly) increased the sensitivity to low doses of isoprenaline. In conclusion the present data demonstrate that NO plays an important role in adrenergic lipolysis in adipose tissues and further investigations are needed to unravel the exact role of NO in lipolysis.

Adipose Tissue↗

von Willebrand factor antigen, tissue-type plasminogen activator antigen, and risk of death in human immunodeficiency virus 1-related clinical disease: independent prognostic relevance of tissue-type plasminogen activator.

Tissue-type plasminogen activator, von Willebrand factor, and plasminogen-activator inhibitor type 1 plasma levels were measured at first consultation in 85 consecutive patients infected with human immunodeficiency virus. Patients were assigned to three groups according to clinical status: mild disease group, intermediate group, and acquired immunodeficiency syndrome group. Significant differences were found in von Willebrand factor, tissue-type plasminogen activator, and plasminogen-activator inhibitor type 1 plasma levels among the three groups: severe clinical status was associated with higher von Willebrand factor, tissue-type plasminogen activator, and plasminogen-activator inhibitor type 1 plasma levels. Significant correlations were found among these three parameters, such known biologic prognostic indicators of human immunodeficiency virus infection as IgA, anti-p24 antibodies, p24 antigenemia, CD4+ lymphocytes, beta 2-microglobulin, and the clinical status. The prognostic relevance of plasma von Willebrand factor and tissue-type plasminogen activator levels at the time of entry into the study was then investigated in a cohort of 65 of the 85 patients who had follow-up during a median period of 22 months. The median survival time for all patients was 39 months after the first consultation. A plasma von Willebrand factor level greater than 200% of the control value had a positive predictive value of 86% for determining nonsurvivors; the median survival time for such patients was 9 months after the first consultation. A positive predictive value of 100% in recognizing nonsurvivors was found for tissue-type plasminogen factor plasma levels greater than 20 ng/ml; the median survival time for these patients was 2 months after the first consultation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

[Experimental study of tissue-engineered heart tissue using type I collagen as scaffold].

OBJECTIVE: To construct tissue-engineered heart tissue (EHT) using liquid collagen as scaffold. METHODS: Neonatal rat cardiac myocytes were isolated, cultured, and mixed with liquid collagen type I and matrix factors and then cast in circular molds to construct circular cardiac myocytes/collagen strand. After a 7-day culture in circular molds, the strands were removed, and subjected to 10% static stretch for another 7 days. Microscopy and transmission electron microscopy, routine HE staining and immunohistochemical staining were used to analyze the engineered heart tissue. RESULTS: Beating areas could be seen on the surface of the EHTs at the second day after stretching; more beating areas could be seen thereafter. These areas beat stronger and stronger, and finally came to synchronzation. Histological and immunohistochemical analyses showed that the cardiac myocytes in the EHTs distributed evenly in the whole strand and the majority of the cells, with elongated nuclei, stretched along the stretching direction. The morphology of EHTs resembled that of the native adult cardiac tissue. Transmission electron microscopy revealed that the cardiac myocytes in EHTs contained arranged myofibrils oriented parallel to the longitudinal cell axis. Clearly defined sarcomeres and Z lines were observed. CONCLUSION: Liquid type I collagen is a good scaffold for generation of EHTs similar to the native heart tissue.

Animals↗

Tissue-specific expression of the mouse alpha 2(I) collagen promoter. Studies in transgenic mice and in tissue culture cells.

We sought to determine the cis-acting elements responsible for the pattern of tissue specific expression of the mouse alpha 2(I) collagen gene. Using an RNase protection assay we first verified that expression of the alpha 2(I) collagen gene is mainly confined to tendons, bone, and skin in mice. Both transgenic mice and DNA transfection of tissue culture cells were used as experimental approaches. Transgenic mice lines were generated harboring chloramphenicol acetyltransferase (CAT) chimeric genes that contained either (a) 2000 base pairs (bp) of 5'-flanking sequences of the mouse alpha 2(I) collagen gene plus additional sequences between +418 and +1524 of the first intron of this gene or (b) the same promoter sequences without intron sequences or (c) the 350-bp proximal promoter sequences. Transgenic mice containing both types of 2000-bp promoters showed a pattern of CAT expression that was tissue specific. The presence of sequences of the first intron in the transgene did not increase the level of promoter activity. Transgenic mice harboring the 350-bp alpha 2(I) collagen promoter also showed a pattern that was tissue-specific except that high level expression also occurred in the brain. This suggests that negative regulation is an important component of tissue-specific expression. In order to analyze the first 350 bases in detail, we performed transient expression experiments, using promoter fragments attached to the luciferase reporter gene. Fibroblasts, which show a high level expression of the endogenous alpha 2(I) collagen gene, and B cells, in which the gene is silent, were transfected with a series of deletions and substitution mutations within the proximal 350-bp promoter. These experiments were unable to define unique cell-specific cis-acting elements. However, when the sequence between -315 and -284 was tandemly repeated upstream of a minimal alpha 2(I) collagen promoter (-41 to +54), the activity of this construction was considerably higher in fibroblasts than in B cells when compared with the minimal promoter itself. In gel retardation assays, the levels of complexes that bind to this sequence were higher in fibroblast nuclear extracts than in myeloma nuclear extracts. Our results are consistent with the hypothesis that the -315 to -284 DNA sequence participates in the cell-specific control of the alpha 2(I) collagen gene in fibroblasts.

Animals↗

[Reconstruction of soft tissue defects in oral and maxillofacial regions after tumors surgery using cervical pedicle tissue flaps].

OBJECTIVE: To report 4 methods of reconstructing soft tissue defects in oral and maxillofacial regions after tumors resection using cervical pedicle tissue flaps. METHODS: One hundred seventy-two soft tissue defects were repaired with cervical myocutaneous flaps after resection of oral and facial cancer (165 cases of squamous cell carcinoma and 7 cases of salivary carcinoma). The clinical stage of the tumors was stage I in 21 cases, stage II in 116 cases and stage III in 35 cases. Primary sites of the lesions were the tongue (59 cases), buccal mucosa (55 cases), lower gingiva (26 cases), floor of the mouth (25 cases), parotid gland (4 cases) and oropharynx (3 cases). Infrahyoid myocutaneous flaps were used in 60 cases, platysma flaps in 45 cases, sternocleidomastoid flaps in 59 cases and submental island flaps in 8 cases. The sizes of skin paddle ranged from 2.5 cm x 5.0 cm to 5.0 cm x 8.0 cm. RESULTS: Among 153 survival flaps, there were 55 infrahyoid myocutaneous flaps, 40 platysma flaps, 52 sternocleidomastoid flaps and 6 submental island flaps. There were 11 cases of total flap necrosis and 8 cases of partial flap necrosis. The success rates were 91.67% (55/60) for infrahyoid myocutaneous flap, 88.89% (40/45) for platysma flap, 88.14% (52/59) for sternocleidomastoid flap and 75% (6/8) for submental island flap. After a follow-up of 3 11 years (5.7 years on average) among 101 cases local recurrence in 18 cases, cervical recurrence in 4 cases, distance metastasis in 2 cases. The survival rate at 3 years were 83.17% (84/101). CONCLUSION: Cervical pedicle tissue flaps have clinical value in reconstruction of small and medium-sized soft tissue defects after resection of oral and maxillofacial tumors.

Adult↗

Consent for organ and tissue retention in British law in the light of the Human Tissue Act 2004.

The experience from the scandals in hospitals at Liverpool and Bristol in the UK where retention of tissue and organs was undertaken without the consent of the parents and relatives raised serious concerns regarding the efficacy of the existing Human Tissue Act 1961, in England and the operation of the law by medical practitioners. In the aftermath of these damaging scandals a combination of public distrust and government overreaction has led to the enactment of new legislation, the Human Tissue Act 2004, which is aiming to prevent any further instances of the retention of organs and tissue from dead children or adults without their next of kin's consent or knowledge. However, scientists have expressed concerns that such changes might seriously endanger several medical research programmes, and also tissue and organ donation for transplantation. The aim of this article is to highlight important issues raised by existing practice in the post-mortem examinations in the UK and the lessons learnt from this and to discuss the benefits and the potential problems arising from the new Act.

Autopsy↗

Characterization of rat 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase cDNAs and differential tissue-specific expression of the corresponding mRNAs in steroidogenic and peripheral tissues.

The conversion of 3 beta-hydroxy-5-ene steroids by the enzyme complex 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD) is an essential step in the biosynthesis of all classes of hormonal steroids. We report the characterization of two types of cDNA clones encoding rat 3 beta-HSD isolated from a rat ovary lambda gt11 cDNA library with a human 3 beta-HSD cDNA probe. Both type I and type II cDNAs encode proteins of 372 amino acids having 94% homology. Transient expression of the type I and the type II 3 beta-HSD cDNAs in HeLa human cervical carcinoma cells reveals that both proteins possess 3 beta-hydroxysteroid dehydrogenase as well as delta 5-delta 4 isomerase activities for both delta 5-pregnene and delta 5-androstene precursors, although the type I 3 beta-HSD protein is more active than the type II. RNA blot analysis using type I 3 beta-HSD cDNA identifies major mRNA transcripts of 1.7 kilobase in rat ovary, testis, and adrenal poly(A)+ RNA. RNase protection assay using type I- and type II-specific cRNA probes revealed the existence of the two corresponding mRNAs in male and female rat adrenals and gonads as well as in female adipose tissue while only type I mRNA is present in male and female kidney. Moreover, in situ hybridization performed using type-specific labeled 24-mer oligonucleotides confirms that type I is the major mRNA species in the ovary and further indicates that both mRNA species have a similar cellular distribution in the ovarian tissue with the highest level of expression found in corpora lutea. Immunoblot analysis using polyclonal antibodies raised against purified human placental 3 beta-HSD identified a single 42-kDa band in rat ovary, testis, and adrenal, which agrees with the calculated molecular masses of 41,911 and 42,150 daltons for the type I and II proteins, respectively. Determination of 3 beta-HSD enzymatic activity using [14C]pregnenolone and [14C]dehydroepiandrosterone as substrates shows that 3 beta-HSD activity is present not only in the gonads and adrenals of animals of both sexes, but also in many peripheral tissues including adipose tissue, mammary gland, kidney, liver, prostate, seminal vesicle, uterus, skin, brain, heart, thymus, pancreas, lung, and spleen. The present data indicate the existence of two mRNAs encoding rat 3 beta-HSD and their differential tissular distribution in both steroidogenic and peripheral tissues.(ABSTRACT TRUNCATED AT 400 WORDS)

Adipose Tissue↗

[Obesity and adipose tissue. 2. Hormonal regulation of adipose tissue metabolism].

The effects of hormones on human adipose tissue are reviewed with respect to the pathogenesis, prevention and therapy of obesity. Insulin. The insulin-resistance in the obese is associated with a decrease of the number of insulin receptor sites, which is likely to be secondary to increased insulin levels. Catecholamines. Human adipose tissue contains alpha- and beta-adrenergic receptors. Alterations in the relation of alpha- and beta-adrenergic responsiveness may be important in the pathogenesis of regional forms of obesity. Gastrointestinal hormones. As opposed to adipose tissue of other species lipolytic effects of gastrointestinal hormones were as yet not clearly demonstrated in human fat cells. Prostaglandins were implicated in the pathogenesis of metabolic obesity. However, the effects of these C-20 fatty acids on human adipose tissue remain to be elucidated. Parathyroid hormone has been shown to possess lipolytic activity in vitro. This property may be important under physiological conditions too. Triglyceride storage diseases and lipomatoses are discussed as models for studying impaired hormonal responsiveness in human adipose tissue.

Adipose Tissue↗

Tissue inhibitor of metalloproteinases-2 (TIMP-2) mRNA expression in tumor cell lines and human tumor tissues.

Human tissue inhibitor of metalloproteinase-2 (TIMP-2) was cloned and sequenced from an A2058 human melanoma cell cDNA library. When the sequence was compared with that of human TIMP-1 at both the nucleotide and deduced amino acid levels, the homology appeared closer at the protein level than at the nucleotide level, suggesting that these inhibitors diverged early in the evolution of this gene family. Comparison of the deduced amino acid sequence for TIMP-2 with that of human TIMP-1 shows that there are two regions in which the similarity is below the overall average of 66%. It is postulated that these regions are responsible for the unique ability of TIMP-2 to bind to the latent form of the 72-kDa type IV collagenase. Polyclonal anti-TIMP-2 antisera recognized TIMP-2 but not TIMP-1 on immunoblotting. Northern blot analysis of RNA from A2058 human melanoma, HT-144 human melanoma, HT-1080 human fibrosarcoma, and WI-38 fetal lung fibroblast cell lines demonstrated two distinct transcripts of 1.0 and 3.5 kilobases (kb) for timp-2 mRNA. Both transcripts are down-regulated in response to transforming growth factor-beta but are unchanged in response to phorbol ester treatment. This is in contrast to the up-regulation of timp-1 transcripts by these agents and indicates that timp-2 and timp-1 are independently regulated in cell culture. Northern blot analyses of matched normal and tumor tissue samples from five cases of human colorectal carcinoma were performed. Normal and tumor tissues contain both the 1.0- and 3.5-kb transcripts. However, in the tissue samples the ratio of the 3.5-kb transcript to the 1.0-kb transcript was markedly elevated. No evidence of down-regulation of timp-2 transcript levels was noted in the tumor tissues. This is in contrast to the elevated timp-1 transcript levels seen in these tumor samples. Thus, timp-2 mRNA transcript levels are differentially regulated from timp-1 levels in vivo as well as in cell culture.

Amino Acid Sequence↗

Muscle tissue in obesity with different distribution of adipose tissue. Effects of physical training.

Obese men and women with the same body fat mass, as well as obese women in another study, were divided into groups with male or female type of body fat distribution, but again with similar body fat mass. The participants were examined with measurements of body composition, including muscle fiber distribution, as well as circulatory and metabolic variables before and after physical training under controlled conditions. Obese men had higher lean body mass, blood pressure, blood glucose and plasma insulin, C-peptide, cholesterol and triglyceride concentrations than age- and body fat-matched obese women. Obese women with male type of adipose tissue distribution showed the same differences (except cholesterol) in comparisons with women with female type of adipose tissue distribution. The women with male type obesity were also more insulin resistant in glucose clamp measurements, and had male type of muscle fiber distribution. Physical training in the group of obese men resulted in a decrease of body fat, a further increase of lean body mass, an increase of fast twitch, aerobic type, muscle fibres as well as lower plasma insulin, cholesterol and triglyceride concentrations and lower blood pressure. Obese women with male type distribution of adipose tissue responded to physical training essentially like men. The insulin sensitivity was improved to the same level as in obese women with female type of adipose tissue distribution. In contrast, the latter women showed an increase of body fat and no metabolic improvements after training. These results show that obese women with male type of body fat distribution also have male characteristics of muscle mass, morphology and function. It is suggested that the obesity complications associated with this condition are improved by physical training because of an adaptation to a negative energy balance, in combination with an improvement of insulin sensitivity of the muscle mass. In contrast, the failure of obese women with female type of adipose tissue distribution to adapt to a negative energy balance during physical training is probably explaining their failure to decrease body fat and to improve metabolism during physical training.

Adipose Tissue↗

Effect of the combined lipase deficiency mutation (cld/cld) on ultrastructure of tissues in mice. Diaphragm, heart, brown adipose tissue, lung, and liver.

Lipoprotein lipase and hepatic lipase activities are very low in tissues of mice born with genetic combined lipase deficiency (cld/cld). Consequently, if allowed to suckle, the mice develop severe hyperlipemia and die within 3 days. The ultrastructure of capillaries and parenchymal cells in tissues that normally contain lipoprotein lipase and hepatic lipase was studied in tissues from cld/cld and unaffected mice 6 to 24 hours of age. Capillaries in tissues from suckled cld/cld mice were packed with numerous abnormally shaped chylomicrons. There was close contact between surfaces of chylomicrons and the luminal plasma membrane of endothelium. Chylomicrons were sometimes found between endothelial cells and in the subendothelial space in heart, lung, and liver, and in the lumen of lung alveoli. In contrast, capillaries of suckled unaffected mice contained very few chylomicrons, and the subendothelial spaces and lung alveoli were free of chylomicrons. Myocytes of diaphragm and heart from suckled cld/cld mice did not contain lipid droplets, whereas brown adipocytes contained a few small droplets. Parenchymal cells in diaphragm, heart, brown adipose tissue, and lung from suckled unaffected mice contained numerous large lipid droplets. Hepatocytes of suckled cld/cld mice contained small irregularly shaped lipoprotein particles (100 A) in endoplasmic reticulum and Golgi, numerous large lysosomes containing small lipoprotein particles, lipid spheres and lamellar structures, and no intracellular lipid droplets, whereas hepatocytes of suckled unaffected mice contained larger lipoprotein particles (400 A), large lipid droplets, and very few lysosomes. Triacylglycerol of chylomicrons from cld/cld mice was readily hydrolyzed by bovine lipoprotein lipase in vitro, and this effect was not augmented by heat-inactivated serum, indicating that the chylomicrons contained adequate amounts of apoprotein C-II. Thus, the large amount of chylomicrons in capillaries and small amount of lipid droplets in cells of suckled cld/cld mice reflect the very low level of lipoprotein lipase activity in these animals. The findings in hepatocytes indicate that lipoprotein metabolism in liver is markedly disturbed in cld/cld mice.

Adipose Tissue, Brown↗

X-ray microanalysis of biological tissues--an examination of comparative specimen preparation techniques using prostatic tissue as a model.

A number of reproductive tissues have been investigated by X-ray microanalysis for a large number of elements. These elements occur both free and with many different forms of binding to tissue proteins and cellular constituents. The prostate tissue studied here represents a glandular tissue with both parenchymal and stromal components having different cell types. While no general rule can be applied to the preparative technique for all tissues, it would seem that of all the methods examined here freeze substitution or the use of dehydration fluids combined with subsequent embedding offer the most promising compromise between cryoultramicrotomy and aqueous fixation.

Animals↗