Muscle transformation of the sartorius muscle in a canine model: clinical impact for electrodynamic graciloplasty as a "neosphincter"

PURPOSE: Transformation of fast-twitching skeletal muscles to slow-twitching, slowly fatigable muscles has become of clinical interest in the recent past. Transposition and transformation of the gracilis muscle to use it as a substitute for a resected or defected anal sphincter (graciloplasty) have been reported as achieving promising results in the treatment of fecal incontinence caused by sphincter defects or following abdominoperineal anorectal excision for cancer. METHOD: This experimental study used a canine model and the sartorius muscle to evaluate the functional efficiency of two different configurations of the muscle loop to compare the presently applied transformation program (8 weeks) with a shorter (5 weeks) protocol. In six beagle dogs, both sartorius muscles were wrapped around two stomas, either in an alpha fashion or in the so-called split-sling technique. Muscle transformation was achieved by controlled neuromuscular stimulation either during eight (Program A) or five weeks (Program B). After completion of the transformation period, the function of the muscle slings was evaluated by manometry, and histomorphologic evaluation of the sartorius muscles was performed. RESULTS: It was shown that muscle transformation led to a slowly fatigable muscle that made it possible to perform continuos (tetanic) contraction, regardless of the configuration or the duration of the transformation. Median pressures created by these muscles also did not differ significantly. In accordance with these functional findings, the histologic evaluation showed the typical, significant increase of Type I fibers in both muscle slings and following both transformation protocols. Although the decrease of fast-twitching Type II fibers was more pronounced following the conventional (8 weeks) program, this finding did not influence the functional results. CONCLUSIONS: Results of our experiment indicate the possibility for using a shorter transformation protocol for transformation of the gracilis muscle during graciloplasty in the clinical setting. Furthermore, the efficacy and safety of the modified (split-sling) wrap technique was demonstrated.     

Rapid intraoperative construction of autologous small caliber blood vessels

Autologous pericardium, briefly tanned in glutaraldehyde, is an excellent biomaterial when used in various cardiac procedures, including repair and replacement of heart valves. A generalized lack of calcification and an absence of inflammatory response in these combined experiences has led the authors to consider the use of treated autologous pericardium for the construction of substitute small caliber blood vessels. Rapid, intraoperative construction of a vascular graft from autologous pericardium, briefly treated in 0.62% glutaraldehyde, is accomplished through the use of two concentric, mating helical stents that support a rectangular pattern of tissue into a cylindrical, nonkinking, compliant conduit. A disposable automated assembly tool provides for precise assembly of the tissue and stents. The tools and methods for construction of vascular grafts from nonvascular tissue are known as the Rapidgraft (Ramus Medical Technologies, Santa Barbara, CA). The technique can be used with any suitable tissue. Accelerated fatigue test studies have confirmed that stent supported pericardial grafts are capable of withstanding physiologic pressures and flows beyond 7 equivalent years. Six autologous pericardial grafts measuring 5 mm in diameter by 5.5 cm in length showed 100% patency beyond 5 months in a growing calf carotid artery model. Pathological examination of explanted grafts confirm the presence of a continuous endothelial lined surface, infiltration of the tissue by fibrous connective tissue such that the individual layers of the pericardial vessel wall could not be identified, and there was no inflammatory response. Based on the encouraging results in animal studies, a small multicenter clinical trial has been initiated to evaluate the performance of the Rapidgraft as a replacement conduit for the radial artery in cases in which the radial artery has been harvested as a coronary artery bypass conduit. Results from the radial artery trial will be used as an indication to evaluate the Rapidgraft as a coronary artery substitute. We conclude that the material properties, including the biological origin of a vessel wall, may be significant determinants of graft patency, and that the Rapidgraft may be an answer to the need for small caliber arterial graft with the potential for long-term patency and durability.     

Phosphorylation of contractile proteins in heart and skeletal muscle

Contractile performance of cardiac and skeletal muscles may be regulated by cyclic AMP or Ca2+, two second messengers that stimulate the phosphorylation of specific myofibrillar proteins. Cyclic AMP-dependent protein kinase catalyzed the rapid phosphorylation of a single site in the inhibitory subunit of cardiac troponin in vitro and in perfused hearts. Skeletal muscle troponin was not phosphorylated by this enzyme in vivo. Although there was a correlation between cardiac troponin phosphorylation and the positive inotropic response to catecholamines, a biochemical mechanism that could account for a functional relationship between the two processes has not been discovered. Phosphorylation of skeletal muscle myosin was catalyzed by myosin light chain kinase in the presence of Ca2+ and the ubiguitous, multifunctional Ca2+-dependent regulator protein (CDR). The activation of kinase activity appeared to proceed via a trimolecular reaction process in which Ca2+ bound to CDR and the Ca2+.CDR complex then interacted with the enzyme. In rat extensor digitorum longus muscle, a 1 sec tetanic contraction resulted in phosphorylation of myosin light chain with the maximal phosphate incorporated 20 sec after the contraction. The light chain phosphate content declined slowly and correlated to post-tetanic potentiation of isometric twitch tension. Phosphorylation of skeletal muscle myosin may be important in modulating contraction.     

Sex difference in distribution and iron responsiveness of the two ferritins of rat cardiac and skeletal muscle

The presence of two electrophoretically and structurally distinguishable forms of ferritin ("fast" and "slow") in cardiac and skeletal muscle (diaphragm) of the rat was confirmed. Although the total amount of cardiac ferritin showed no difference in concentration in male and female rats, the distribution between the fast and slow species was markedly different in the two sexes, the fast form predominating in the cardiac muscle and diaphragm of the female. In agreement with this, the rates of synthesis and of degradation of the fast species were greater in the female, while the opposite obtained for the male. Iron administration stimulated synthesis of each ferritin species in the cardiac muscle and diaphragm of both sexes. Induction of cardiac connective tissue hypertrophy with isoproterenol inverted the ratio of slow to fast ferritin in female rats, while iron administration along with isoproterenol restored this to normal. It is concluded that the metabolism of ferritin in cardiac and skeletal muscle is sensitive both to sexual status and to iron administration.     

Signal transduction via phosphorylated adhesion molecule, LFA-1 beta (CD18), is increased by culture of natural killer cells with IL-2 in the generation of lymphokine-activated killer cells

Anti-human platelet myosin antibodies and two anti-peptide antibodies, anti-peptide IIA and anti-peptide IIB, which recognize macrophage-type (MIIA) and brain-type (MIIB) isoforms of nonmuscle myosin heavy chain, respectively, were used to study expression of nonmuscle myosin isoforms in various tissues of mice during development. Tissue-specific changes in the relative isoform concentrations were observed by performing immunoblots of crude myosin extracts from nonmuscle and muscle tissues. In fetal and neonatal mouse tissues, the anti-peptide IIB antibodies stained a single band, called MIIB2, while the anti-peptide IIA and anti-platelet myosin antibodies stained a band that migrated faster than MIIB2. In brain, a slower moving band, MIIB1, started to appear at 2 weeks after birth, and in the adult cerebellum it was at least as abundant as MIIB2. In thymus, MIIB2 decreased selectively shortly after birth, while in liver both MIIB2 and MIIA rapidly disappeared, but the isoform(s) detected by anti-platelet myosin antibodies (MIIApla) remained constant. The MIIB2 and MIIA as well as MIIApla found in striated muscles from fetal and neonatal mice decreased to levels that were below the limit of detection by 3 weeks of age. In cryosections of skeletal and cardiac muscles, MIIB2 was localized within the muscle cells, while MIIA and MIIApla were primarily in the blood vessels and capillaries.     

Traumatic myositis ossificans. Posttraumatic non-neoplastic heterotopic ossification

Myositis ossificans traumatica (MOT) is a nonneoplastic, heterotopic ossification of soft tissues i.e. skeletal muscle, tendons, aponeuroses and fascia. It is often encountered in young male athletes participating in contact sports as a result of a single or repeated contusion. MOT tends to be solitary, localized and well circumscribed with a self-limited growth potential that may culminate in regression. The pathogenesis of MOT is still enigmatic. Recent animal experiments have led to a theory that mesenchymal connective tissue cells, undergo metaplasia induced by trauma and probably osteogenic proteins, to fibroblasts and osteoblasts. These cells deposit and structure osteoid centripetally in the lesion. As the lesion matures, cancellous bone develops into mature, lamellar bone in the periphery of the lesion. In its earlier stages MOT is easily cytologically and radiologically confused with osteogenic sarcoma. The management of MOT is largely conservative and the principles are of considerable value to physicians and physiotherapists engaged in the treatment of sports injuries. This article reviews the various forms of myositis ossificans as well as the pathology, diagnosis and treatment options.     

The subunit structure of myosin from skeletal muscle of the early chick embryo

The subunit composition and immunological properties of two types of myosins, the 3S and 6S myosin components, from skeletal muscle of early chick embryos were studied by SDS-acrylamide gel electrophoresis and immunodiffusion techniques. It was shown that the 6S myosin in the early embryonic stage was composed of two heavy chains and three kinds of light chains, as is well-known in the complete myosin molecule, having the same molecular weights and the same antigenicities as corresponding subunits of the myosin from adult chicken skeletal muscle. The heavy chain of 6S myosin was also reactive with the antibody against the heavy chain of cardiac myosin. The embryonic 3S myosin was shown to be composed of a heavy chain which was roughly the same in molecular weight but not the same in antigenicity as those of adult or embryonic 6S myosin. No light chains were detected either electrophoretically or immunologically in the 3S myosin component.     

Enteroscopy for unexplained iron-deficiency anemia: identifying the patient with sprue

The behaviour of bovine pericardium was studied using a fatigue assay. Twenty-three samples were assayed, maintaining the preset initial stress and measuring the time it took for the onset of load loss due to permanent deformation. The results indicated a mathematical relationship defined by the expression: log y = 1.3 - 0.211 log t, where y is the fatigue stress (MPa) and t the duration of the assay. The correlation coefficient was 0.948 (P < 0.001). The safety coefficient of the material diminished significantly as the period of time during which it was subjected to fatigue increased. The theoretical durability of the tissue was much greater than the real durability of the prostheses, which is determined by unsolved problems such as calcification and those derived from suture-related cutting.     

Familial hypertrophic cardiomyopathy: from mutations to functional defects

Hypertrophic cardiomyopathy is characterized by left and/or right ventricular hypertrophy, which is usually asymmetric and involves the interventricular septum. Typical morphological changes include myocyte hypertrophy and disarray surrounding the areas of increased loose connective tissue. Arrhythmias and premature sudden deaths are common. Hypertrophic cardiomyopathy is familial in the majority of cases and is transmitted as an autosomal-dominant trait. The results of molecular genetics studies have shown that familial hypertrophic cardiomyopathy is a disease of the sarcomere involving mutations in 7 different genes encoding proteins of the myofibrillar apparatus: ss-myosin heavy chain, ventricular myosin essential light chain, ventricular myosin regulatory light chain, cardiac troponin T, cardiac troponin I, alpha-tropomyosin, and cardiac myosin binding protein C. In addition to this locus heterogeneity, there is a wide allelic heterogeneity, since numerous mutations have been found in all these genes. The recent development of animal models and of in vitro analyses have allowed a better understanding of the pathophysiological mechanisms associated with familial hypertrophic cardiomyopathy. One can thus tentatively draw the following cascade of events: The mutation leads to a poison polypeptide that would be incorporated into the sarcomere. This would alter the sarcomeric function that would result (1) in an altered cardiac function and then (2) in the alteration of the sarcomeric and myocyte structure. Some mutations induce functional impairment and support the pathogenesis hypothesis of a "hypocontractile" state followed by compensatory hypertrophy. Other mutations induce cardiac hyperfunction and determine a "hypercontractile" state that would directly induce cardiac hypertrophy. The development of other animal models and of other mechanistic studies linking the genetic mutation to functional defects are now key issues in understanding how alterations in the basic contractile unit of the cardiomyocyte alter the phenotype and the function of the heart.     

Functional morphology of serially linked skeletal muscle fibers

In the skeletal muscle fiber organization of many vertebrate muscles, serial arrangements or linkages of muscle fibers along the muscle or fascicle are commonly found. These serially linked muscle fibers employ distinct junctional morphologies from muscle to muscle. Notable are the end-to-end linkages of muscle fibers through tendinous intersections (TIs), where many fibers end onto a continuous connective tissue plate with folded terminations similar to myotendinous junctions. Besides this end-to-end linkage, overlapping linkages or arrangements occur among nonspanning fibers terminating intrafascicularly. These nonspanning fibers bear tapering terminations with direct cell-cell (myomuscular) junctions or without any specialized junctions. Despite their overlapping linkages or tapering profiles, nonspanning fibers maintain a uniform sarcomere length along the linked fibers, suggesting that the overlapping-linked nonspanning fibers are equivalent to the end-to-end linked fibers in their mechanical capacity. However, the junctional compliance could differ in their extracellular elastic components and their organization at junctional sites, e.g., direct mechanical (myomuscular) junctions vs. indirect linkages through connective tissue. Increasing evidence suggests that the elastic components, including muscle fibers as well as connective tissues, are more critical than previously thought for the mode and/or the efficiency of tension transmission among serially arranged fibers and thus for the mechanical properties of the muscle.     

Nucleotide-dependent conformational change near the fulcrum region in Dictyostelium myosin II

In skeletal muscle myosin, the reactive thiols (SH1 and SH2) are close to a proposed fulcrum region that is thought to undergo a large conformational change. The reactive thiol region is thought to transmit the conformational changes induced by the actin-myosin-ATP interactions to the lever arm, which amplifies the power stroke. In skeletal muscle myosin, SH1 and SH2 can be chemically cross-linked in the presence of nucleotide, trapping the nucleotide in its pocket. Although the flexibility of the reactive thiol region has been well studied in skeletal muscle myosin, crystal structures of truncated nonmuscle myosin II from Dictyostelium in the presence of various ATP analogs do not show changes at the reactive thiol region that would be consistent with the SH1-SH2 cross-linking observed for muscle myosin. To examine the dynamics of the reactive thiol region in Dictyostelium myosin II, we have examined a modified myosin II that has cysteines at the muscle myosin SH1 and SH2 positions. This myosin is specifically cross-linked at SH1-SH2 by a chemical cross-linker in the presence of ADP, but not in its absence. Furthermore, the cross-linked species traps the nucleotide, as in the case of muscle myosin. Thus, the Dictyostelium myosin II shares the same dynamic behavior in the fulcrum region of the molecule as the skeletal muscle myosin. This result emphasizes the importance of nucleotide-dependent changes in this part of the molecule.     

Primary structure of the kinase domain region of rabbit skeletal and cardiac muscle titin

A 2.3 kb region of rabbit cardiac and skeletal muscle titin has been cloned. The cDNA sequences of the two tissues are identical and show 91% identity on the nucleotide level with the corresponding region of human cardiac muscle titin. On the amino acid level the identity is 96% and similarity is 98%. Alignment of predicted amino acid sequences of several homologous kinase domains reveals that the rabbit titin kinase has all the necessary elements of an active catalytic domain and carries a potential regulatory region on its C-terminal end. The distance of the 2.3 kb contig from the 3' end of the message was determined to be 5.7 kb in both tissues using oligonucleotide directed RNase H cleavage of titin mRNAs. This is essentially identical with the length of the fully sequenced human cardiac titin C-terminal end. It therefore appears unlikely that there are major tissue specific differences in this 8 kb cDNA region which encodes the C-terminus of rabbit skeletal and cardiac titin.     

Social isolation increases aggressive behaviour and alters the effects of diazepam in the rat social interaction test

Doppler echography is now the most accurate noninvasive method for studying valvular prostheses, but the values considered to prove a normal function are still controversial. We studied by echo Doppler 95 valvular mechanical (M) and biological (B) prostheses, in mitral (Mi) and aortic (Ao) position in patients without clinical signs of prosthetic dysfunction. The data obtained for Ao prostheses (maximal transprosthetic gradient (MxG): M-20.47 mmHg, B-7.95 mmHg; mean transprosthetic gradient (MG): M-7.98 mmHg, B-3.9 mmHg) are in agreement or even better than literature data. For Mi prostheses the prosthetic area (PA) and pressure half time (PHT) values are in normal limits but the MG (M-5.087 mmHg, B-5.9 mmHg) is slightly superior to the data reported in the literature. Proving the value of echo Doppler for the study of valvular prostheses our results suggest to adopt larger limits of normality for mitral prostheses. They also sustain the necessity of a first Doppler examination before the patient is discharged from the hospital after valvular replacement.     

L-Carnitine: therapeutic applications of a conditionally-essential amino acid

A trimethylated amino acid roughly similar in structure to choline, carnitine is a cofactor required for transformation of free long-chain fatty acids into acylcarnitines, and for their subsequent transport into the mitochondrial matrix, where they undergo beta-oxidation for cellular energy production. Mitochondrial fatty acid oxidation is the primary fuel source in heart and skeletal muscle, pointing to the relative importance of this nutrient for proper function in these tissues. Although L-carnitine deficiency is an infrequent problem in a healthy, well-nourished population consuming adequate protein, many individuals within the population appear to be somewhere along a continuum, characterized by mild deficiency at one extreme, and tissue pathology at the other. Conditions which seem to benefit from exogenous supplementation of L-carnitine include anorexia, chronic fatigue, coronary vascular disease, diphtheria, hypoglycemia, male infertility, muscular myopathies, and Rett syndrome. In addition, preterm infants, dialysis patients, and HIV+ individuals seem to be prone to a deficiency of L-carnitine, and benefit from supplementation. Although available data on L-carnitine as an ergogenic aid is not compelling, under some experimental conditions pretreatment has favored aerobic processes and resulted in improved endurance performance.     

Inhibitory effect of Escherichia coli endotoxin on skeletal muscle contractility

OBJECTIVE: Endotoxemia in rabbits is associated with decreases in oxygen transport, tissue hypoxia, metabolic acidosis, and impaired oxygen extraction. In this study, we tested the hypothesis that endotoxin also inhibits skeletal muscle contractility directly. DESIGN: Randomized animal study. SETTING: Accredited animal research facility. SUBJECTS: New Zealand white rabbits of either sex, weighing 2.55 +/- 0.20 kg. INTERVENTIONS: We compared two groups of rabbits (n = 10 each) undergoing continuous electrical stimulation of the left hindlimb (maximal isometric twitch contraction at 0.25 Hz). One group (septic) was given an intravenous infusion of Escherichia coli endotoxin. The control group was subjected to decreases in cardiac output by inflating a balloon placed in the right ventricle. MEASUREMENTS AND MAIN RESULTS: Endotoxin or balloon inflation resulted in comparable decreases in cardiac output (49% and 53%, respectively). Hindlimb oxygen transport decreased to similar values for both groups (4.9 +/- 0.3 and 4.2 +/- 0.5 mL/min/kg, respectively). Systemic oxygen extraction ratio was greater in the control group (0.72 +/- 0.03) than in the septic group (0.55 +/- 0.04; p < .05). There were no differences in hindlimb oxygen extraction ratio. Decreases in hindlimb forces were greater in the septic group (42 +/- 4%) than in the control group (18 +/- 3%, p < .01). Force frequency curves obtained at the beginning and the end of the experiment showed greater fatigue in the septic group. CONCLUSIONS: The intravenous infusion of Escherichia coli endotoxin produces a direct inhibitory effect on skeletal muscle contractility in rabbits. This phenomenon is independent of decreases in oxygen transport and blood pH. Our data support the notion of a direct cellular effect of endotoxin, or of an associated cytokine, on skeletal muscle contractility. The mechanism responsible for this phenomenon is unknown.     

Determination of platinum in tumour tissues after cisplatin therapy by electrothermal atomic absorption spectrometry

The paper is devoted to the study on enzymatic and regulatory properties of skeletal muscle myosin of hibernating ground squirrels (Citellus undulatus) for the purpose of elucidating the contribution of myosin and myosin filaments to the change of physiological state of the animal at the different stages of hibernation (hibernation, arousing, winter activity). It has been revealed that actin-activated ATPase activity of myosins of hibernating and arousing ground squirrels is less by 60 and 20%, correspondingly, than that of the myosin of active animals. In the absence of troponin-tropomyosin complex the Ca(2+)-sensitivity of actomyosins of the hibernating and arousing ground squirrels is less by 60 and 55%, correspondingly, than that of the actomyosin of active animals. The results obtained by us point to the essential decrease of functional properties of the main contractile protein, myosin upon hibernation, which evidently contributes to the inhibition of moving capacity of skeletal muscles at this period.     

Smooth and skeletal muscle myosin both exhibit low duty cycles at zero load in vitro

Smooth muscle's stress equals that of skeletal muscle with less myosin. Thus, under isometric conditions, smooth muscle myosin may spend a greater fraction of its cycle time attached to actin in a high force state (i.e. higher duty cycle). If so, then smooth muscle myosin may also have a higher duty cycle under unloaded conditions. To test this, we used an in vitro motility assay in which fluorescently labeled actin filaments move freely over a sparsely coated (5-100 micrograms/ml) myosin surface. Actin filament velocity (V) was a function of the number of cross-bridges capable of interacting with an actin filament (N) and the duty cycle (f), V = (a x Vmax) x (1-(1-f)N) (Uyeda et al., 1990; Harada et al., 1990). N was estimated from the myosin density on the motility surface and the actin filament length. Data for V versus N were fit to the above equation to predict f. The duty cycle of smooth muscle myosin (4.0 +/- 0.7%) was not significantly different from that of skeletal muscle myosin (3.8 +/- 0.5%) in agreement with values estimated by Uyeda et al. (1990) for skeletal muscle myosin under unloaded conditions. The duty cycles of smooth and skeletal muscle myosin may still differ under isometric conditions.     

Persisting in vitro actin motility at nanomolar adenosine triphosphate levels: comparison of skeletal and cardiac myosins

We have previously demonstrated in vitro actin movement at nanomolar adenosine triphosphate (ATP) levels using heavy meromyosin from skeletal muscle. In the present work we tested whether the motility at nonomolar ATP-concentrations could be supported by cardiac myosin as well. Actomyosin (skeletal actin and bovine ventricular myosin) was pretreated in the in vitro motility assay with 1 mM ATP; subsequently, the ATP level was reduced by multiple rigor-solution washes. By the final rigor-solution wash, the ATP concentration, monitored by the luciferin-luciferase assay, dropped to the order of 100 nM. Even at this low ATP level actin-filament movement remained in evidence. This was in marked contrast to the situation where ATP concentration was gradually increased from zero; in the latter, filament movement began only as ATP levels exceeded 1-2 microM. The difference indicates that potential energy is stored during the initial ATP treatment, and utilized later as the free ATP falls below micromolar levels. Although the velocity of cardiac myosin-supported movement was only one fourth of that of skeletal myosin, both myosins supported actin movement down to similar ATP concentrations. The similarity in response of the two myosins to ATP implies a similar degree of potential energy storage. Given the significantly different specific ATPase activities, however, it appears that the mechanism of potential energy storage and release involves factors different from those involved in the release of chemical energy by the myosin ATPase.     

Dietary supplementation with carotenoids: effects on alpha-tocopherol levels and susceptibility of tissues to oxidative stress

The ability of dietary supplementation with carotenoids to protect chick tissues against oxidative stress in vitro was examined. Male Leghorn chicks were fed on diets supplemented (100 mg supplement/kg diet) with either beta-carotene, zeaxanthin (beta,beta-carotene-3,3'-diol), canthaxanthin (beta,beta-carotene-4,4'-dione) or alpha-tocopherol, or on a control diet, from 1 d old until 37 d of age. Tissues (liver, heart, skeletal muscle and plasma) were removed and assayed for total carotenoids and alpha-tocopherol content and portions subjected to oxidative stress by incubation of homogenates with cumene hydroperoxide and FeSo4. Animals receiving zeaxanthin and canthaxanthin had significantly greater carotenoid concentrations in liver, heart, muscle and plasma compared with untreated controls (P < 0.05); animals fed on diets supplemented with beta-carotene, or alpha-tocopherol did not have significantly different tissue carotenoid contents compared with untreated controls. alpha-Tocopherol supplementation elevated alpha-tocopherol levels in all tissues examined (P < 0.05). Supplementation with carotenoids did not affect tissue alpha-tocopherol levels, but beta-carotene lowered plasma alpha-tocopherol levels by 50% (P < 0.05). Incubation of plasma or tissue homogenates with oxidant stressors induced lipid peroxidation (production of thiobarbituric-acid reactive substances) in all tissues. Animals given alpha-tocopherol, beta-carotene or zeaxanthin had a reduced susceptibility to oxidant stress in liver compared with unsupplemented controls (P < 0.05), and alpha-tocopherol-supplemented animals had reduced susceptibility in skeletal muscle compared with tocopherol-supplemented animals had reduced susceptibility in skeletal muscle compared with unsupplemented controls (P < 0.05). Canthaxanthin supplementation did not influence the susceptibility to oxidant stress in any tissue examined. These results suggest that zeaxanthin, a carotenoid present in animal and human diets, may have significant activity as an antioxidant against oxidative stress in tissues.     

Characterization of a monoclonal antibody recognizing mast cells

Immunohistochemical screening for monoclonal antibodies prepared by immunization of mice with a rat osteoblastic cell population led to identification of one antibody that reacted against a small population of cells present in the soft connective tissue compartment of 21 days fetal rat calvaria. The morphology of the cells and the immunohistochemical staining characteristics (a distinct intracellular granular pattern) suggested that the antibody might be reacting specifically against mast cells. We used combined histochemistry and immunohistochemistry to further characterize this antibody, designated RCJ102. Cryosections containing calvaria bone, soft connective tissues and skin were prepared from the top of the head of 21 days fetal rats, and from adult rats cryosections of lung, muscle, adipose tissue and small intestine were prepared. Some sections were labelled by indirect immunofluorescence with RCJ102; corresponding sections were labelled histochemically with toluidine blue. There was a direct correspondence between mast cells identified histochemically and cells labelling with RCJ102 in all tissues except intestine, in which the mast cell detectable by histochemistry were not labelled by RCJ102. These results suggest that the RCJ102 antibody will be a valuable new reagent for further elucidation of the heterogeneity described between connective tissue and intestinal mucosal mast cells.