Cellular adaptations in soleus muscle during recovery after hindlimb unloading

AIM

We used a model of chronic unloading followed by reloading to examine the apoptotic responses associated with soleus muscle atrophy and subsequent recovery.

METHODS

Male Wistar rats were subjected to hindlimb unloading (HU) for 2 weeks and subsequent reloading for 0, 3, 7 and 14 days. One-half of the HU-reloaded rats were administered cyclosporine A (CsA), a calcineurin (CaN) inhibitor.

RESULTS

There was fibre atrophy (73%) and a decrease in slow type I fibre/myosin heavy chain (MyHC) composition in the soleus muscle after 2 weeks of HU. Fibre size and type I MyHC composition recovered to near the age-matched control levels by recovery day 14 in non-treated, but not in CsA-treated, rats. Myonuclear number was lower and the number of apoptotic nuclei higher in 2-week HU than control rats. These values returned to control levels after 7 and 14 days of recovery, respectively, in both HU-recovery groups. After 2 weeks of HU, the levels of heat shock proteins (Hsp) 60 and 72, mitochondrial cytochrome c oxidase subunit IV (Cox IV), and peroxisome proliferator-activated receptor gamma coactivator 1 (PGC-1) proteins were lower than control. The levels of all of these proteins gradually increased to or above the control levels during cage recovery in both groups.

CONCLUSION

Our results indicate that apoptotic mechanisms are involved in the modulation of myonuclear number during chronic unloading and subsequent reloading. Furthermore, it appears that CaN is related to fibre size and phenotype adaptations, but not to apoptotic responses.

Growth hormone therapy and scoliosis in patients with Prader-Willi syndrome

Growth hormone (GH) therapy for short stature in patients with Prader-Willi syndrome (PWS) has started worldwide, and various favorable effects have been reported. However, the possibility of progression of scoliosis arises as a new problem of the GH therapy. In this study, we analyzed whether 72 patients who have been followed up in our hospital have such a problem. They included 46 males and 26 females (41 patients with the GH therapy and 31 without it) aged from one to 49 years. Consequently, 33 (45.8%) of 72 patients had scoliosis with the Cobb angle of >10 degrees. Twenty (48.8%) of forty-one patients who received a GH therapy and 13 (41.9%) of 31 patients without the therapy had scoliosis, the frequency of scoliosis between the two groups showing no statistical difference (P = 0.56). Height velocity of scoliotic and non-scoliotic patients during the first year of the therapy was 8.59 +/- 1.92 and 10.70 +/- 2.54 cm, respectively, showing a significant difference (P < 0.001). This shows that accelerated height velocity may not induce scoliosis. Comparison of starting age of a GH treatment revealed that non-scoliotic patients received the therapy earlier than scoliotic patients (P = 0.021). Among 20 scoliotic patients who received the GH therapy, the degree of scoliosis progressed during the therapy in six patients, improved in three and fluctuated in one. Many patients showed progression of scoliosis with age irrespective of the use of GH, and some patients improved their scoliosis during the GH therapy. These findings showed that a GH therapy increases height velocity of PWS patients but does not necessarily develop scoliosis, and early start of the therapy may not be an exacerbating factor of scoliosis.

Effect of bovine lactoferrin on the immune responses of captive bottlenosed dolphins (Tursiops truncatus) being transported over long distances

Bovine lactoferrin was administered orally, in feed, to six bottlenosed dolphins (Tursiops truncatus) before they were transported for approximately six hours; their stress responses were compared with those of five untreated dolphins. During the journey the dolphins had an increased plasma concentration of cortisol, and lymphopenia, eosinopenia and mild neutrophilia, indicating a stress response. The administration of lactoferrin did not affect the function of the dolphins' polymorphonuclear leucocytes, but affected their leucogram by maintaining the number of circulating eosinophils.

Relation between the TIMI frame count and the degree of microvascular injury after primary coronary angioplasty in patients with acute anterior myocardial infarction

OBJECTIVE

To investigate the relation between thrombolysis in myocardial infarction (TIMI) frame count (TFC) and coronary blood flow velocity (CBFV) parameters reflecting the degree of microvascular injury in patients with acute myocardial infarction.

RESULTS

TFC and CBFV were measured after primary coronary angioplasty in 103 consecutive patients with their first anterior wall acute myocardial infarction. TFC correlated inversely with the averaged peak velocity (r = -0.43, p < 0.0001). However, TFC did not correlate significantly with diastolic deceleration time and with the averaged systolic peak velocity (r = -0.16, p = 0.22, and r = -0.23, p = 0.16, respectively). The patients were divided into two groups according to presence (35 patients) or absence (68 patients) of systolic flow reversal. There was no significant difference in TFC between the two groups (29 (16) v 25 (13), p = 0.20).

CONCLUSIONS

These findings suggest that the TFC reflects epicardial CBFV. However, it is not accurate enough to assess the degree of microvascular injury after primary coronary angioplasty.

An angiogenesis inhibitor TNP-470 (AGM-1470) suppresses vascular smooth muscle cell proliferation in experimental rat aortotomy models

AIM

Vascular intimal hyperplasia is an important clinical concern in vascular diseases, such as anastomotic stricture as a possible complication of cardiovascular surgery. We recently suggested that a rat aortotomy model could be substituted for a vascular anastomotic stricture around a suture line. TNP-470 is known as an angiogenesis inhibitor and has demonstrated abilities to inhibit DNA synthesis of smooth muscle cells (SMCs) and SMCs proliferation. The aim of this study was to investigate the effect of TNP-470 on SMC proliferation using rat aortotomy models.

METHODS

Longitudinal aortotomy was performed in the abdominal aorta of rats. Rats received a subcutaneous injection of materials (TNP-470, 20 mg/kg) or vehicle 3 times a week (n=10 in each group). The aorta was harvested 2 weeks after aortotomy. Serial sections from tissues were stained with hematoxylin and eosin, and the ratio of intimal to medial cross-sectional areas (I/M ratio) was determined. Values are expressed as the mean +/- the standard deviation. Results. Thickening of the intimal layer 2 weeks following aortotomy was observed in the control group however, intimal thickening was inhibited in the TNP-treated group. The I/M ratio was significantly (p = 0.0376) lower in the TNP-treated group than in the control group (8.3 +/- 4.8 vs 15.6 +/- 9.6%). Conclusion. TNP-470 significantly suppressed intimal thickening in experimental rat aortotomy models. TNP-470 might inhibit the development of anastomotic stricture after cardiovascular surgery.

Induction of insulin production in rat pancreatic acinar carcinoma cells by conophylline

We set up a screening system to detect low-molecular-weight compounds that induce insulin expression in pancreatic acinar carcinoma AR42J cells. They can differentiate into insulin-producing cells with neuron-like morphological change when treated with activin A. We employed this morphological change for the screening of beta-cell inducers among various signal transduction inhibitors. As a result, a vinca alkaloid, conophylline, induced neurite formation at 0.1 approximately 0.3 microg/ml in 72 h, like activin A. Conophylline-treated cells were found to express insulin as measured at both mRNA and protein levels. By RT-PCR analysis, conophylline-treated cells were shown to express neurogenin3 strongly. They also expressed Beta2/NeuroD and Nkx2.2, but not Pax4 and PP. Although activin A induces nuclear translocation of Smad2, conophylline did not. But the latter induced p38 activation, like activin A, as detected by phosphorylation. Pretreatment with a p38-specific inhibitor, SB203580, lowered the conophylline-induced insulin production. Therefore, p38 activation would be involved in the differentiation of AR42J cells into insulin-producing cells. Studies on structure-activity relationship with conophyllidine, conofoline, conophyllinine, and related monomer alkaloids showed that the dimeric aspidosperma structure with the dihydrofuran unit in its center was essential for the differentiation-inducing activity.

The proportion of cells with functional X disomy is associated with the severity of mental retardation in mosaic ring X Turner syndrome females

Turner syndrome females (45,X) do not have mental retardation (MR), whereas some mosaic ring X Turner syndrome females, with 45,X/46,X,r(X), have severe MR. The MR is believed to be caused by a failure of X chromosome inactivation (XCI) of the small ring X chromosome, which leads to functional X disomy (FXD), To explore this hypothesis, we examined the proportion of FXD cells in the peripheral blood of four ring X Turner syndrome females with various levels of MR, using two newly developed XCI assays based on DNA methylation of X-linked genes. As a result, the two patients with extremely severe MR showed complete FXD patterns, whereas the remaining two patients with relatively milder MR showed partial FXD patterns. These results indicate that the proportion of FXD cells may be associated with the severity of MR in mosaic ring X Turner syndrome females, although this association should be confirmed by examining brain cells during development. One of the cases with severe MR and a complete FXD pattern neither lacked the XIST gene nor had uniparental X isodisomy, and we discuss the mechanism of the failure of XCI in this case.

Clenbuterol induces expression of multiple myosin heavy chain isoforms in rat soleus fibres

Clenbuterol, a beta2-agonist, administration results in hypertrophy of fast fibres and an increase in the fast myosin heavy chain (MHC) composition of both fast and slow muscles. The present study was designed to determine the phenotypic response at the single fibre level. Clenbuterol was added to the drinking water (30 mg L(-1)) of adult male Wistar rats for 4 weeks. Single fibres from the soleus muscle of control (10 rats; 555 fibres) and clenbuterol-treated (10 rats; 577 fibres) were dissected and their MHC isoform composition was determined using sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis. Body, heart, and soleus weights were 9, 24, and 27% higher in clenbuterol-treated than control rats. The mean cross-sectional areas of fast and slow/fast hybrid fibres were approximately 64 and approximately 74% larger in the clenbuterol-treated than control rats, whereas the size of the slow fibres were similar in the two groups. Fibres from control soleus showed three MHC patterns: pure type I (84%), pure type IIa (4%), and type I + IIa (12%) MHC. Some fibres from clenbuterol-treated soleus showed a de novo expression of type IIx MHC resulting in the following fibre type proportions: pure type I (62%), pure type IIa (2%), type I + IIa (26%), type I + IIa + IIx (6%), and type IIa + IIx (1%). In those fibres containing multiple MHCs, there was a shift towards the faster MHC isoforms after clenbuterol treatment. These data indicate that clenbuterol results in muscle fibre hypertrophy, stimulates a de novo expression of type IIx MHC and increases the percentage of fibres containing multiple MHC isoforms in the rat soleus muscle. These phenotypic changes at the single fibre level are consistent with a clenbuterol-related shift in the functional properties of the soleus towards those observed in a faster muscle.

Androgen receptor gene and male genital anomaly

Male sexual differentiation, testicular descent, and spermatogenesis require androgens. Their action is mediated through the androgen receptor (AR), which binds to the androgen responsive element on DNA and regulates gene transcription. No mutations in any of the AR gene exons 1-8 are detected in males with isolated cryptorchidism, hypospadias, micropenis, or idiopathic male infertility. In addition, the CAG repeat length in exon 1 of the AR gene does not expand in males with isolated cryptorchidism, hypospadias, micropenis, or idiopathic male infertility. These facts indicate that an alteration of the AR gene is rare in these males. However, further studies will permit a better clarification on the relevance of the AR gene abnormalities to the development of isolated cryptorchidism, hypospadias, micropenis, or impaired spermatogenesis.

Three-dimensional organization of mammalian skeletal muscle membrane systems

The three-dimensional arrangement of mitochondria and sarcoplasmic reticulum membrane systems of vertebrate extrafusal and intrafusal muscle fiber types was studied by scanning electron microscopy (SEM) in the specimens prepared by the A-ODO method. SEM observations on specimens treated by HCl-digestion method revealed distinct differences in motor endplates in the different muscle fiber types.

The tubulovesicular system of gastric parietal cells is connected to the intracellular canaliculus, rough endoplasmic reticulum and Golgi complex. A study by high resolution scanning electron microscopy

The three-dimensional configuration of the tubulovesicular system of resting rat gastric parietal cells was determined by ultra-hihg-resolution scanning electron microscopy (SEM). Rat gastric mucosae were fixed in 1.0% glutaraldehyde and 0.5% formaldehyde in cacodylate buffer, (334 milliosmoles/kgH2O (mOsm)). To render cytoplasmic membranes visible by SEM, fixed mucosae were frozen and fractured, and the cytoplasm of fractured parietal cells was macerated by the aldehyde-osmium-DMSO-osmium procedure. With much of the cell matrix and filaments removed, SEM revealed numerous 30-60 nm tubukes, which formed a meshwork and also small cisternae about 100 nm. Some cisternae had a small, central 10 nm fenestration. The cytoplasmic surface of the tubules was smooth surfaced but some cisternal areas had attached polyribosomes. Isolated vesicles or tubules were not found in adequately macerated parietal cells. The tubulocisternal network was also connected to the Golgi apparatus. In favorable sites connections of the tubular membranes to the canaliculi were clearly visible. Continuity between these two membrane compartments suggests the probability of rapid membrane transposition when cells are stimulated to secrete acid.

Wear of resin-modified glass ionomers: an in vitro study

The purpose of this study was to evaluate the wear resistance and clinical applicability of resin-modified glass ionomer cements as restorative or fissure-sealing materials. The in vitro wear of resin-modified glass ionomers was compared to conventional glass ionomers, a resin-based sealant, and a composite resin. A three-body wear test (enamel block--polymethylmethacrylate powder--experimental dental material) was performed by 20,000 cycles with a load of 4 kgf/cm2. The depth of wear of the experimental materials was measured and calculated using a computerized laser surface scanner. The glass ionomers generally showed more wear than the resin-based sealant and the composite resin, but there was no difference in wear between resin-modified and conventional glass ionomers. Type III ionomers (used for sealant) showed lower wear resistance than type II ionomers (used for restoration).

Aortic valve replacement for aortic stenosis with a small mechanical prosthetic valve

BACKGROUND

Although aortic valve replacement (AVR) is the only effective treatment for patients with aortic stenosis (AS), it is recognized that the use of small prosthetic valves due to a small aortic root often affects postoperative course after AVR. The aim of this study was to determine whether the use of small prosthetic valves was a risk factor of AVR for AS.

METHODS

We compared various perioperative factors and operative outcomes between patients with a small mechanical prosthetic valve (small group) and patients with a large mechanical prosthetic valve (large group).

RESULTS

Early mortality was 0% in each group and the 5-year mortality was 25% in the small group and 10% in the large group. There were no significant differences in perioperative factors between the two groups. The small group patients were significantly older and smaller compared to the large group patients. The valve size was significantly correlated with age and BSA.

CONCLUSIONS

The use of small mechanical prostheses was not a risk factor of AVR for AS when it was proportionate to the BSA even for elderly patients. AVR using a small mechanical prosthetic valve may be performed with good results in the short- and long-term.