[Strategy for post coronary artery bypass grafting in patients with bypass graft stenosis: comparison of percutaneous transluminal coronary angioplasty for the native coronary artery, internal mammary artery and saphenous vein graft]

OBJECTIVES

The strategy for post coronary artery bypass grafting (CABG) was investigated in patients with graft stenosis.

METHODS

The study included 123 post-CABG patients with graft stenosis. The patients were divided into three groups according to target vessels; saphenous vein graft (SVG; n = 72), internal mammary artery (IMA; n = 21) and native coronary artery (n = 30). Furthermore, SVG lesions were divided into proximal anastomosis (n = 23), body (n = 40) and distal anastomosis (n = 9). The procedural success rate and late patency rate were compared between the three groups. Furthermore, the relationships between pre percutaneous transluminal coronary angioplasty (PTCA) percentage diameter stenosis, procedural success rate and late patency rate were evaluated.

RESULTS

Procedural success rate was similar in the three groups, but late patency rate was higher in the IMA group. Procedural success rate and late patency rate were significantly lower in proximal anastomoses compared to other sites of SVG stenoses, IMA group and native coronary artery group (p < 0.05). Totally occluded native coronary artery lesions had a high procedural success rate compared with occluded IMA and SVG lesions, but the late patency rate was not higher. Procedural success rate showed no significant difference for 75-99% stenotic lesions, but the late patency rate was significantly higher in the IMA group (p < 0.05). Patients in the stenting group had a greater late patency rate compared with the balloon angioplasty group. There was no significant difference in late patency rate between the IMA group and SVG group.

CONCLUSIONS

Late patency rate of the IMA is higher than that of the native coronary artery. SVG with proximal anastomosis and severe stenosis shows a significantly lower late patency rate than the native coronary artery. Therefore, PTCA should be considered for the native coronary artery in the absence of chronic total occlusion.

Evaluation of the mechanical destructive force in the stomach of dog

Orally administered dosage forms receive a destructive force in the gastrointestinal (GI) tract due to peristalsis. In this study, the destructive force was measured with a 'destructive force-dependent release system' (DDRS). DDRS is a press-coated tablet with an extremely brittle outer layer composed of highly hydrophobic Teflon(R) powder, which is molded with a weak compression force. Teflon(R) powder forms a porous but water-impermeable layer around the core tablet. A marker drug contained in the core tablet is released only when the tablet receives a force larger than its pre-determined crushing strength. A comparison of the physiological conditions in the GI tract of dogs with those of humans, including the destructive force against tablets in the stomach, helps us to understand their difference in bioavailability of oral dosage forms. With DDRS, it is possible to evaluate the destructive force of both human and dog stomach using the same method. Therefore, the destructive force data from human and dog can be directly compared. The destructive force in the dog stomach was evaluated to be 3.2 N, which was considerably stronger than that of humans.

Functional significance of hemodynamic overload-induced expression of leukemia-inhibitory factor in the adult mammalian heart

BACKGROUND

Leukemia-inhibitory factor (LIF) is a member of the interleukin-6 family of cytokines that utilize gp130 as a common signaling component. In the present study, we examined the mechanisms that govern LIF expression and functional effects in the adult heart.

METHODS AND RESULTS

LIF mRNA and protein biosynthesis were examined in the adult feline heart after hemodynamic overloading ex vivo. Both LIF mRNA and protein expression were detected within 60 to 90 minutes after hemodynamic overloading. Studies in isolated adult cardiac myocytes showed that these cells synthesized both LIF mRNA and protein. The functional effects of LIF in the heart were demonstrated by studies that showed that LIF stimulation led to a significant increase in general protein synthesis and an increase in sarcomeric protein synthesis. Pretreatment with LIF also protected the cells against hypoxia/reoxygenation-induced cardiac myocyte apoptosis and cellular injury. Finally, LIF had no effect on isolated cardiac myocyte cell motion.

CONCLUSIONS

Hemodynamic overload is a sufficient stimulus for LIF expression in the adult mammalian heart. Given that LIF confers both hypertrophic and cytoprotective responses in adult cardiac myocytes, this study suggests that the expression of LIF within the heart may play an important role in mediating homeostatic responses within the myocardium.

Effect of interleukin-18 on viral myocarditis: enhancement of interferon- gamma and natural killer cell activity

Encephalomyocarditis virus causes viral myocarditis with myocyte necrosis and inflammatory cell infiltration in mice. Because previous studies have shown that some cytokines prevent the sequelae of myocarditis, we assessed the effect of a newly identified cytokine, interleukin-18 (IL-18), in preventing the sequelae of myocarditis. Murine IL-18 (10 microg/day/mouse) was given peritoneally for 10 days in C3H mice infected with EMC virus. Mice were divided into group IL-18 (infected-treated), saline group (infected-untreated), group IL-18-2 (treatment started on day 2), group IL-18-5 (treatment started on day 5). Although the 14-day survival rate in saline group was 20%, that in the group IL-18 increased to 80% (P<0.05). Either mice in group IL-18-2 or in group IL-18-5 did not survive longer than saline group. The viral titer of the heart on day 3 was lower in group IL-18 compared to the saline group (1.00+/-0.20 log(10)tissue culture infected dose (TCID)(50)/mg wet weight v 1.42+/-0.12 log(10)TCID(50)/mg, n=3 of each). Mice in group IL-18 had less myocardial necrosis and cellular infiltration than the saline group. The myocardial expression of interferon- gamma (IFN- gamma) mRNA in group IL-18 was significantly (P<0.05) greater than the saline group on days 1 and 3 after viral inoculation. Circulating IFN- gamma was significantly elevated on days 1, 5, and 7, but significantly reduced on day 3. The natural killer cell activities in the spleen on days 1, 3, and 5 were significantly (P<0.05) greater in group IL-18 than in the saline group (41+/-9%v 10+/-6% on day 3, 4 of each). We conclude that IL-18 reduces the severity of EMC viral myocarditis by inducing cardiac expression of IFN- gamma mRNA and increasing splenic natural killer cell activity.

A unique dosage form to evaluate the mechanical destructive force in the gastrointestinal tract

The purpose of this study was to prepare tablets that could evaluate the destructive force in the gastrointestinal (GI) tract. Many factors are known to affect in vivo drug release from oral dosage forms. There is still relatively little information on the mechanical destructive force in the GI tract. Press-coated tablets with an extremely brittle outer layer were developed using a unique, highly hydrophobic Teflon powder that could be shaped with weak compression force. A marker drug contained in the tablets was released only when the tablets received a force larger than its predetermined crushing strength. We referred to this type of tablet as a 'destructive force dependent release system' (DDRS). A total of nine healthy, male subjects were orally administered the tablets under fed and/or fasting conditions. Tablets with a predetermined crushing strength of 1.50 N were crushed by all of the four subjects who took them under fed conditions and two of the five subjects under fasting conditions. Tablets with a crushing strength of 1.89 N were crushed by two of the six subjects who took them under fed conditions and none of the five subjects under fasting conditions. The range of mechanical destructive force in the human stomach was obtained.

Nitric oxide provokes tumor necrosis factor-alpha expression in adult feline myocardium through a cGMP-dependent pathway

BACKGROUND

The mechanism(s) responsible for the persistent coexpression of tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) in the failing heart is unknown.

METHODS AND RESULTS

To determine whether NO was sufficient to provoke TNF-alpha biosynthesis, we examined the effects of an NO donor, S-nitroso-N-acetyl penicillamine (SNAP), in buffer-perfused Langendorff hearts. SNAP (1 micromol/L) treatment resulted in a time- and dose-dependent increase in myocardial TNF-alpha mRNA and protein biosynthesis in adult cat hearts. The effects of SNAP were completely abrogated by a NO quenching agent, 2-(4-carboxyphenyl)-4, 4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (C-PTIO), and mimicked by sodium nitroprusside. Electrophoretic mobility shift assays demonstrated that SNAP treatment led to the rapid induction of nuclear factor kappa-beta (NF-kappaB) but not AP-1. The importance of the cGMP pathway in terms of mediating NO-induced TNF-alpha biosynthesis was shown by studies that demonstrated that 8-bromo-cGMP mimicked the effects of SNAP and that the effects of SNAP could be completely abrogated using a cGMP antagonist, 1H-(1,2, 4)oxadiazolo(4,3-a)quinoxalin-1-one (ODQ), or protein kinase G antagonist (Rp-8-Br-cGMPS). SNAP and 8-Br-cGMP were both sufficient to lead to the site-specific phosphorylation (serine 32) and degradation of IkappaBalpha in isolated cardiac myocytes. Finally, protein kinase G was sufficient to directly phosphorylate IkappaBalpha on serine 32, a critical step in the activation of NF-kappaB.

CONCLUSIONS

These studies show that NO provokes TNF-alpha biosynthesis through a cGMP-dependent pathway, which suggests that the coincident expression of TNF-alpha and NO may foster self-sustaining positive autocrine/paracrine feedback inflammatory circuits within the failing heart.

Interleukin-18 in patients with congestive heart failure: induction of atrial natriuretic peptide gene expression

Activated inflammatory responses appear to play a role in the development of congestive heart failure (CHF). We investigated interleukin-18 (IL-18), which is a cytokine synthesized by activated macrophage, changes in patients with CHF. We evaluated 11 Japanese patients with angina pectoris (n=4) or CHF (n=7). Blood was sampled immediately after admission and at 1, 2, 3, 6, and 9 hours after admission and then every 12 hours until 5 days after admission. Plasma IL-18 concentrations were measured by an enzyme-linked immunosorbent assay. Expression of atrial natriuretic peptide (ANP) mRNA and protein synthesis was examined in cardiac myocyte by stimulation of IL-18. Plasma IL-18 concentration was significantly higher in patients with CHF than in 15 healthy volunteers (51+/-21 pg/mL, and 28+11 pg/mL, respectively, P<0.05). Increased expression of ANP mRNA was demonstrated in IL-18 treated myocytes. Protein synthesis in myocytes was increased by IL-18 in a dose-dependent manner. Increased secretion of IL-18 is induced in patients with CHF and correlates with the severity of myocardial damage and dysfunction.

Therapy with the nonpeptide endothelin receptor antagonist 97-139 in a murine model of congestive heart failure: reduction of cardiac mass and myofiber hypertrophy

Endothelin-1 (ET-1) is a potent vasoconstrictor. This peptide exerts numerous effects on the heart, including regulation of cardiomyocyte growth during hypertrophy. The effects of the structurally novel, nonpeptide, ET-1-selective, competitive antagonist (ETA) 97-139 were investigated in mice with congestive heart failure (CHF) and myocardial hypertrophy. Morphological and microscopical analyses were conducted on day 56 after viral inoculation following 28 day treatment with 99-139. Eight week-old DBA2 mice were intraperitoneally inoculated with encephalomyocarditis virus at a dose of 500 pfu/mouse. The 30 mice were divided into two groups--an ETA treated group and an untreated group. Heart weight (HW) in the infected group was significantly (p < 0.05) increased compared to that in the uninfected group. HW and the HW/body weight (BW) ratio were significantly (p < 0.05) reduced in the ETA treated group compared with the untreated group (HW; 127.7 +/- 6.2 mg vs 144.3 +/- 4.2 mg, HW/BW; 4.9 +/- 0.9 x 10(-3) vs 5.4 +/- 0.5 x 10(-3)). Myofiber diameter in the ETA treated group was significantly reduced compared with the untreated group (12.1 +/- 1.5 microm vs 14.3 +/- 1.9 microm). These results suggest the ET-1 receptor antagonist 97-139 has an effect on the reduction of cardiac mass and myofiber hypertrophy, and that 97-139 may be a useful agent for CHF due to viral myocarditis.

Cytokines in heart failure: pathogenetic mechanisms and potential treatment

Recent studies have shown that patients with heart failure overexpress a class of biologically active molecules, generically referred to as pro-inflammatory cytokines. This article will review recent clinical and experimental material that suggests that pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), and interleukin-6 (IL-6) may play a role in the pathogenesis of congestive heart failure. In addition, we will review recent studies that suggest that antagonizing cytokines may represent a novel target for heart failure therapy.

Safety and efficacy of a soluble P75 tumor necrosis factor receptor (Enbrel, etanercept) in patients with advanced heart failure

BACKGROUND

Although previous studies suggested that TNF may contribute to heart failure progression, it is unclear whether antagonizing TNF is beneficial in heart failure patients.

METHODS AND RESULTS

Eighteen NYHA class III heart failure patients were randomized into a double-blind dose-escalation study to examine the safety and potential efficacy of etanercept, a specific TNF antagonist (Enbrel). Patients received placebo (6 patients) or an escalating dose (1, 4, or 10 mg/m2) of etanercept (12 patients) given as a single intravenous infusion. Safety parameters and patient functional status were assessed at baseline and at days 1, 2, 7, and 14. There were no significant side effects or clinically significant changes in laboratory indices. There was, however, a decrease in TNF bioactivity and a significant overall increase in quality-of-life scores, 6-minute walk distance, and ejection fraction in the cohort that received 4 or 10 mg/m2 of etanercept; there was no significant change in these parameters in the placebo group.

CONCLUSIONS

A single intravenous infusion of etanercept was safe and well tolerated in patients with NYHA class III heart failure. These studies provide provisional evidence that suggests that etanercept is sufficient to lower levels of biologically active TNF and may lead to improvement in the functional status of patients with heart failure.

[Validation of dissolution testing: evaluation of vibration levels of dissolution apparatuses]

The collaborative study participated by seven laboratories was carried out to develop a dissolution standard for evaluating vibration levels of dissolution apparatuses using enteric-coated granules of cefalexin (EG). Dissolution apparatuses could be divided into two groups according to their vibration levels and the dissolution test results of EG by the rotating basket method at 50 rpm. The critical value of acceleration was about 0.05 m/s2. The upper limit of normal dissolution rates of EG was calculated from the results of the rotating basket method at 50 rpm obtained from low vibration apparatuses. All high vibration apparatuses used in this study were distinguished by the limit from low vibration apparatuses, although most of them were not distinguished by current USP calibrators. These results suggest that EG would be useful as a calibrator for detection of apparatuses on high vibration levels.

Merkel cells are responsible for the initiation of taste organ morphogenesis in the frog

Taste organs in the frog have a distinctive cell type located exclusively in the basal portion. In the same fashion as type III cells in mammalian taste buds, these basal cells show immunoreactivity for serotonin antibody. Further, these cells are morphologically similar to epidermal Merkel cells. To determine the significance of these serotonergic basal cells, we examined the early development of taste organs during metamorphosis of the frog by focusing on the origin and possible roles of serotonergic basal cells. For convenience of description, five stages of development (metamorphic stage to climax stages A-D) are defined. In the metamorphic stage, a few noninnervated Merkel cells appear at the upper layer of the lingual epithelium. No neuronal elements are seen in the epithelium at this stage. At climax stages A-B, immature fungiform papillae become discernible in the dorsal surface of the tongue, where the Merkel cells are located. Merkel cells then move downward and extend their cytoplasmic processes toward the basal lamina. These cells are identified by their intense immunoreactivity for serotonin. During the later stages, many nerve fibers in the subepithelial connective tissue approach the epithelium containing Merkel cells. At climax stages C-D, Merkel cells extend cytoplasmic processes along the basal lamina toward the center of the newly forming fungiform papillae. The morphology of these Merkel cells exactly coincides with that of serotonergic basal cells in adult taste organs. Profuse exocytotic release of dense-cored granules of Merkel cells toward the nerve fibers through the basal lamina is frequently seen in these stages. The present study indicates that serotonergic basal cells are derived from intraepithelial Merkel cells, which act as target sites for growing nerves and may be responsible for the initiation of taste organ morphogenesis.

Expression of Mash1 in basal cells of rat circumvallate taste buds is dependent upon gustatory innervation

Mash1, a mammalian homologue of the Drosophila achaete-scute proneural gene complex, plays an essential role in differentiation of subsets of peripheral neurons. In this study, using RT-PCR and in situ RT-PCR, we investigated if Mash1 gene expression occurs in rat taste buds. Further, we examined dynamics of Mash1 expression in the process of degeneration and regeneration in denervated rat taste buds. In rat tongue epithelium, Mash1 gene expression is confined to circumvallate, foliate, and fungiform papilla epithelia that include taste buds. In taste buds, Mash1-expressing cells are round cells in the basal compartment. In contrast, the mature taste bud cells do not express the Mash1 gene. Denervation and regeneration experiments show that the expression of Mash1 requires gustatory innervation. We conclude that Mash1 is expressed in cells of the taste bud lineage, and that the expression of Mash1 in rat taste buds is dependent upon gustatory innervation.

Cardiac remodeling as a consequence and cause of progressive heart failure

Natural history studies in heart failure have shown that increases in left ventricular (LV) volume and LV mass are directly related to future deterioration in LV performance and a less favorable clinical course. Despite the recognized importance of remodeling in heart failure, very little is known about the basic mechanisms that lead to cardiac remodeling. In this review, we will summarize recent clinical and experimental studies that highlight the importance of the remodeling process during the progression of heart failure. The intent of this review is to provide an integrated view of the mechanisms that contribute to LV remodeling at the cellular level, the myocardial level, and the level of the chamber.

Identification of Merkel cells by an antibody to villin

Merkel cells represent a population of epithelial cells in the skin and oral mucosa. Although Merkel cells are reliably distinguishable from other epithelial cells at the ultrastructural level, these cells are usually not discernible by standard light microscopy and need special techniques for their identification. Villin is an actin-crosslinking protein that is associated with the actin filament cores of brush border microvilli. In this study we show that an antibody against villin is an excellent marker of Merkel cells and their microvilli even at the light microscopic level. The surrounding keratinocytes and subepithelial connective tissue cells do not show any significant affinity for the antibody against villin. Confocal laser micrographs reconstructed from serial images 0.5 microm thick of Merkel cells that were immunostained with villin clearly reveal the three-dimensional morphology of Merkel cells and their microvilli. The presence of villin in Merkel cell microvilli lends support to the idea that these cells might have a mechanoreceptor function.

The role of cytokines in the failing human heart

Despite repeated attempts to develop a unifying hypothesis that explains the clinical syndrome of heart failure, no single conceptual paradigm has withstood the test of time. In this regard, recent studies have shown that a class of biologically active molecules, generically referred to as cytokines, are overexposed in heart failure. This article will review recent clinical and experimental material that suggest proinflammatory (stress activated) cytokines such as tumor necrosis factor-alpha (TFN-alpha), interleukin-1 (IL-1), and interleukin-6 (IL-6) may play a role in the pathogenesis of congestive heart failure. The scope of this article includes an overview of the biology of cytokines in the heart, as well as review of the clinical studies that have documented elevated levels of cytokines and cytokine receptors in patients with heart failure.

Pathophysiologically relevant concentrations of tumor necrosis factor-alpha promote progressive left ventricular dysfunction and remodeling in rats

BACKGROUND

Although patients with heart failure express elevated circulating levels of tumor necrosis factor-alpha (TNF-alpha) in their peripheral circulation, the structural and functional effects of circulating levels of pathophysiologically relevant concentrations of TNF-alpha on the heart are not known.

METHODS AND RESULTS

Osmotic infusion pumps containing either diluent or TNF-alpha were implanted into the peritoneal cavity of rats. The rate of TNF-alpha infusion was titrated to obtain systemic levels of biologically active TNF-alpha comparable to those reported in patients with heart failure (approximately 80 to 100 U/mL), and the animals were examined serially for 15 days. Two-dimensional echocardiography was used to assess changes in left ventricular (LV) structure (remodeling) and LV function. Video edge detection was used to assess isolated cell mechanics, and standard histological techniques were used to assess changes in the volume composition of LV cardiac myocytes and the extracellular matrix. The reversibility of cytokine-induced effects was determined either by removal of the osmotic infusion pumps on day 15 or by treatment of the animals with a soluble TNF-alpha antagonist (TNFR:Fc). The results of this study show that a continuous infusion of TNF-alpha led to a time-dependent depression in LV function, cardiac myocyte shortening, and LV dilation that were at least partially reversible by removal of the osmotic infusion pumps or treatment of the animals with TNFR:Fc.

CONCLUSIONS

These studies suggest that pathophysiologically relevant concentrations of TNF-alpha are sufficient to mimic certain aspects of the phenotype observed in experimental and clinical models of heart failure.

Cytomegalovirus infection in the submandibular and parotid salivary glands of an African grass mouse (Arvicanthus dembeensis)

The submandibular and parotid glands of one of five specimens of African grass mice (Arvicanthus dembeensis) were found to be infected with cytomegaloviruses, producing a profound cytomegaly in certain cells at the juncture of secretory endpieces and intercalated ducts. These cytomegalic cells tended to have multiple nuclei, many of which contained a characteristic reticular inclusion. The viruses appeared to arise in association with the intranuclear inclusions, then passed through the nuclear envelope to the cytoplasm where they budded into Golgi saccules or into small vacuoles, presumably of Golgi origin. Fusion of small virus-carrying vacuoles led to the formation of large vacuoles containing a plethora of viruses. Viruses were liberated into gland lumina via fusion of the vacuoles with the luminal plasmalemma. Fusion of vacuoles with dehiscent ones resulted in a form of chain exocytosis. The development of cytomegaloviruses in salivary glands may differ in details in a species-specific manner.

Overexpression of bcl-2 protein inhibits terminal differentiation of oral keratinocytes in vitro

The bcl-2 proto-oncogene is a known inhibitor of apoptosis; in normal human stratified squamous epithelium, its expression is restricted to the basal cell layer. To investigate the functional role of bcl-2 protein in the process of differentiation of oral keratinocytes, bcl-2 expression vector was transfected into SCC-25 cells, which normally undergo squamous cell differentiation in vitro while expressing specific differentiation markers, e.g., keratin 10/11 and involucrin. In bcl-2 transfected SCC-25 cells, the expression of these differentiation markers was markedly suppressed. The bcl-2 proto-oncogene may play a critical role in opposing the commitment to terminal differentiation and apoptosis of oral keratinocytes.

Ultrastructure of the salivary glands in the midtongue of the common vampire bat, Desmodus rotundus

BACKGROUND

All examined mammals have at least two sets of lingual salivary glands: von Ebner's glands and Weber's glands. A third set, the glands of Blandin and Nuhn, is present in the tongues of some but not all mammals. Vampire bats, Desmodus rotundus, are unusual in that they possess another set of lingual glands, these being in the midtongue region.

METHODS

The anterior half of the tongue was extirpated from several adult vampire bats, dissected, and tissue blocks derived from the midregions of the body of the tongue prepared for transmission electron microscopy by conventional means.

RESULTS

The midlingual glands are in the form of long, tubular secretory endpieces that are succeeded by ducts of simple morphology. In general, the secretory portions consist of two cell types, which may be intermingled in the same tubule or may form tubules that consist wholly of one cell type or the other. Seromucous cells usually have one or several rough endoplasmic reticulum cisternae that are hugely distended by a homogeneously dense material. Their granules have a bizonal substructure: one or several dense bands are embedded in a lighter matrix. Mucous cells are rather typical in structure, but their secretory product is different from run-of-the-mill mucous droplets. These droplets vary in density from cell to cell. In some cells, these droplets have a relatively light matrix; in other cells, the droplet is unusually dense, consisting mainly of a dark, structureless matrix with marginal lenticular lacunae of low density in which some short, irregular filaments are scattered. A rare finding is the presence of ciliated cells intermingled with secretory endpiece cells. The cilia are of conventional morphology. Secretory tubules are succeeded by ducts that resemble intercalated ducts; the epithelium of these ducts gradually increases in height to form a kind of excretory duct, without the intervention of striated ducts. As the ducts approach the lingual surface, the epithelium changes to stratified squamous.

CONCLUSIONS

Saliva produced by the midlingual glands may be an aid in the reciprocal grooming behavior of vampire bats. Based on their morphology, the excurrent ducts may not modify the initial saliva elaborated by these glands and might act simply as pipelines by which the saliva reaches the mouth.

Keratinocytes become terminally differentiated in a process involving programmed cell death

Oral keratinocytes originate from basal cells, differentiate during migration to the surface, and finally are shed. Apoptosis occurs at the end of differentiation, but the precise relationship between terminal differentiation and apoptosis is not clear. In the present study, Bcl-xL was expressed in the basal cell and spinous cell layers, and Bax was expressed in the spinous cell and granular cell layers. In cultured keratinocytes, Bcl-xL was expressed under conditions of 0.1 mM calcium (low Ca2+) but disappeared under conditions of 1.0 mM calcium (high Ca2+); the latter induces keratinocyte differentiation. Bax was not expressed in keratinocytes with low Ca2+ but was expressed in cells with high Ca2+. Finally keratinocytes with high Ca2+ underwent apoptosis, which was detected by the TUNEL method and by 180-bp DNA fragmentation. These results suggest that the process of terminal differentiation in gingival epithelium is a pathway to apoptosis.

Expression of a mutant (Arg92Gln) human cardiac troponin T, known to cause hypertrophic cardiomyopathy, impairs adult cardiac myocyte contractility

The mechanism(s) by which mutations in sarcomeric proteins cause hypertrophic cardiomyopathy (HCM) remains unknown. A leading hypothesis proposes that mutant sarcomeric proteins impair cardiac myocyte contractility, providing an impetus for compensatory hypertrophy. To test this hypothesis, we determined the impact of expression of a mutant (Arg92Gln) human cardiac troponin T (cTnT), known to cause HCM in humans, on adult cardiac myocyte contractility. A full-length human cTnT cDNA was cloned, and the Arg92Gln mutation was induced. Recombinant adenoviruses Ad5/CMV/cTnT-N and Ad5/CMV/cTnT-Arg92Gln were generated through homologous recombination. Adult feline cardiac myocytes were infected with recombinant adenoviruses or a control viral vector (Ad5 delta E1) at a multiplicity of infection of 100. Expression levels of the full-length normal and mutant cTnT proteins were equal on Western blots. Expression of the exogenous cTnT proteins in cardiac myocytes was also shown by immunocytochemistry and immunofluorescence, and their incorporation into myofibrils was confirmed by Western blotting on myofibrillar extracts. Electron microscopy showed intact sarcomere structure in rod-shaped cardiac myocytes in all groups. Cell fractional shortening and the peak velocity of shortening were not significantly different among the groups 24 hours after transduction. However, 48 hours after transduction, both fractional shortening and the peak velocity of shortening were significantly reduced (24% [P < .001] and 26% [P < .001], respectively) in cardiac myocytes in the Ad5/CMV/cTnT-Arg92Gln compared with the Ad5/CMV/cTnT-N groups. The magnitude of the reductions was greater at 72 hours after transduction (45% and 39%, respectively; P < .001). Our results indicated that expression of the mutant (Arg92Gln) cTnT, known to cause HCM in humans, impaired intact adult cardiac myocyte contractility. Our data also show that both normal and mutant cTnT were incorporated into myofibrils. These results provide a potential mechanism by which mutations in sarcomeric proteins cause HCM.

Isolation, partial purification, and ultrastructure of taste bud cells from rabbit foliate papillae

A method is described for obtaining large numbers of isolated taste bud cells from lingual epithelium of rabbit foliate papillae. The isolation method is based on isopyenic sedimentation in a Percoll gradient. The purification of taste bud cells was evaluated by electron microscopy and by immunohistochemistry using CK 20 antibody. The cytology of the isolated taste bud cells remained very similar to in situ cells. The type III cells, which are regarded as gustatory cells, retained their characteristic dense-cored granules in the cytoplasm. This method will permit study of various parameters of taste bud cell biology.