Usefulness of intracoronary administration of fasudil, a selective Rho-kinase inhibitor, for PCI-related refractory myocardial ischemia

BACKGROUND

Intra-procedural myocardial ischemia as an iatrogenic complication still remains a critical issue in contemporary interventional cardiology. The aim of this study was to examine the usefulness of fasudil, a selective Rho-kinase inhibitor, for percutaneous coronary intervention (PCI)-related myocardial ischemia.

METHODS

Among 448 PCI sessions performed between October 2015 and December 2017, we retrospectively examined 36 patients (69.0 ± 9.1 [SD] yrs., M/F 26/10) who underwent intracoronary administration of fasudil during a procedure to resolve myocardial ischemia that was resistant to intracoronary nitrate administration.

RESULTS

The refractory myocardial ischemia was caused by distal embolization (69%), enhanced vasoconstriction at distal site of chronic total occlusion (11%), coronary spasm (11%), and coronary dissection (8%), most of which occurred immediately after balloon or stent dilatation. Intracoronary fasudil significantly improved corrected TIMI frame count (from 37 [30-56] to 24 [12-36]) and TIMI flow grade (from 2 [1-2.5] to 3 [2-3]) (both P < 0.001). Finally, 86% of all subjects successfully obtained TIMI flow grade 3 at the end of the procedure. Intracoronary fasudil tended to be more effective in patients with an attenuated plaque detected by intravascular ultrasound. Importantly, among the 19 elective cases, fasudil successfully prevented 17 patients from developing post-procedure myocardial infarction. Although fasudil-induced transient hypotension requiring a vasopressor was noted in 22% of the subjects, no other adverse effects were noted.

CONCLUSIONS

These results indicate that fasudil is a useful and safe therapeutic option for PCI-related myocardial ischemia refractory intracoronary nitrate.

92Transcatheter aortic valve implantation improves cerebral blood flow and cognitive function in elderly patients with aortic stenosis - Brain perfusion SPECT imaging study

Background

Cognitive impairment and depression are commonly noted in elderly frail patients with severe aortic stenosis (AS). However, their mechanisms and reversibility after treatment remain remain to be examined.

Purpose

In this study, we examined whether transcatheter aortic valve implantation (TAVI) increases cerebral blood flow (CBF) in cognitive/emotional brain areas, such as the hippocampus, in the elderly patients with severe AS.

Methods

We examined consecutive 15 right-handed patients with severe AS who were eligible for TAVI (median age 83.2 years, 12 (80%) women). We evaluated the following assessments both at baseline and 3 months after TAVI. Frailty was evaluated based on Fried scale, which consists of 5 items, including gait speed, cognitive function, weight loss, exhaustion, and inactivity. Frail and pre-frail were defined as greater than 3 and 1∼2 in the scale, respectively. Cognitive and emotional status were evaluated with Logical Memory (LM) II, Mini Mental State Examination (MMSE), and geriatric depression scale (GDS). Lower LM II (less than 4 points) and MMSE (less than 24 points) and higher GDS (more than 6 points) indicate worse memory, general cognitive function, and depressive symptoms, respectively. CBF images were recorded with 99mTc single-photon emission computed tomography and were analyzed using SPM12. Briefly, CBF images were firstly normalized to the standard Montreal Neurological Institute space. Then, a voxel-wise parametric analysis was conducted between normalized CBF images at baseline and those after TAVI (P<0.005 at each voxel). Continuous variables were presented as mean ± standard error (SE). Normality was assessed using the Shapiro-Wilk test. Continuous variables were compared with the use of paired t test. Linear mixed-model analysis was performed to evaluate changes in neuropsychological tests and CBF over time.

Results

In the present study, all patients were not robust but pre-frail (47.3%) or frail (53.7%). LM II score was significantly improved at 3 months after TAVI compared with baseline (baseline, 8.7 vs. 3 months, 13.8, P<0.01) (Figure A), whereas no significant changes in MMSE or GDS scores were noted (baseline, 24.6 vs. 3 months, 25.2 for MMSE; baseline, 4.3 vs. 3 months, 4.2 for GDS). Importantly, although no patients showed clinical symptoms or signs for transient ischemic attack or stroke after TAVI, CBF in the local regions, including the right hippocampus, was significantly increased after TAVI compared with baseline (P<0.005 at each voxel) (green arrowheads) (Figure B). Furthermore, CBF in the right hippocampus were positively correlated with LM II scores (P=0.017) (Figure C).

Figure 1

Conclusions

These results provide the first evidence that TAVI improves cerebral perfusion (especially that in the hippocampus) and cognitive functions in elderly patients with severe AS.

P3575Clinical importance of fractional flow reserve in patients with organic coronary stenosis and vasospastic angina

Background

Vasospastic angina (VSA), which is one of the important functional cardiac disorders, may also play a role in the pathogenesis of atherosclerosis. Conversely, organic coronary stenosis is also known as an independent predictor for poor clinical outcomes in VSA patients. Although VSA patients have a variable degree of organic coronary stenosis in clinical setting, the functional importance of organic stenosis in those patients remains to be elucidated.

Purpose

The aim of this study was to examine the clinical importance and prognostic impact of fractional flow reserve (FFR) in patients with VSA and organic coronary stenosis.

Methods

We enrolled 236 consecutive patients with suspected vasospastic angina who underwent acetylcholine provocation test for coronary spasm (M/F 148/88, 63.6±12.0 [SD] yrs.). Among them, 175 patients (74.1%) were diagnosed as having VSA, while the remaining non-VSA patients were regarded as controls (Group-C, n=61). We divided the VSA patients into 3 groups based on angiographical findings and FFR values; VSA with no organic stenosis (>50% luminal stenosis) (Group-N, n=110), organic stenosis and high FFR (≥0.80) (Group-H, FFR 0.87±0.05, n=36), and organic stenosis and low FFR (<0.80) (Group-L, FFR 0.71±0.07, n=29). We evaluated the incidence of major adverse cardiovascular events (MACE), including cardiovascular death (CVD), non-fatal myocardial infarction (MI), urgent percutaneous coronary intervention (PCI), and hospitalization due to unstable angina pectoris (UAP) during the median follow-up period of 656 days.

Results

The groups with organic stenosis (Groups H and L) were characterized by higher prevalence of diabetes mellitus (Group-C/N/H/L, 23.0/20.9/44.4/34.5%, P=0.03) and dyslipidemia (Group-C/N/H/L, 37.7/39.1/50.0/65.5%, P=0.03) as compared with Group-C. After provocation test, all VSA patients received calcium channel blockers (CCBs). In addition, 20 days (median) after provocation test, 26 patients (92.9%) in Group-L underwent elective PCI with coronary stents, while no patient underwent PCI in Groups N or H. The incidence of MACE during follow-up was significantly higher in Group-L (Group-C/N/H/L; 1.6/3.6/5.6/27.6%, log-rank P<0.001), whereas clinical outcomes were comparable among the remaining 3 groups (Figure). Importantly, all 8 patients with MACE in Group-L had poor outcomes (CVD/MI/urgent PCI/UAP; 2/1/3/2) despite complete revascularization and the prevention of coronary spasm with CCBs, indicating that they might be resistant to standard contemporary therapies. They were characterized by less frequent use of angiotensin convert enzyme inhibitor (0 vs. 47.6%, P=0.02) and higher prevalence of multi-vessel organic lesions (37.5 vs. 4.8%, P=0.052) compared with those without MACE.

Figure 1

Conclusions

These results provide the first evidence that evaluation of coronary functional abnormalities with FFR is useful for making therapeutic strategies in VSA patients with organic coronary stenosis.

3332Exercise training ameliorates vasodilator capacity of coronary microvessels in patients with vasospastic angina - A new therapeutic approach for the coronary functional disorder

Background

We have recently demonstrated that coronary vasospasm could develop in both epicardial coronary arteries and intramuscular coronary microvessels in patients with vasospastic angina (VSA). However, it remains to be examined whether vasodilator capacity of coronary microvessels is impaired in VSA patients and if so, whether exercise training could ameliorate vasodilator capacity of coronary microvessels on the top of calcium channel blockers. The effectiveness of exercise training is established for organic coronary artery disease but remained to be examined for VSA.

Purpose

We thus examined whether vasodilator capacity of coronary microvessels is impaired in VSA patients without organic coronary stenosis using an adenosine-stress dynamic computed tomography perfusion (CTP) that can measure absolute value of myocardial blood flow (MBF). We also examined whether exercise training ameliorates not only vasodilator capacity of coronary microvessels but also exercise capacity and frequency of angina attack.

Methods

In the first protocol, we measured MBF using CTP in consecutive 32 VSA patients with acetylcholine-induced diffuse coronary spasm in the left anterior descending coronary arteries (LAD) and 12 non-VSA controls. In the second protocol, we conducted a randomized controlled trial (RCT; Exercise VSA trial, UMIN: ehz745.008423996), where 20 VSA patients were randomly assigned to either exercise group (Ex group: supervised exercise training session for 30-min using bicycle ergometer, once/week at the hospital and more than 3 times/week at home) or non-exercise group (Non-Ex group) (n=10 each) (Figure A). Before and 3 months after exercise training, we measured MBF with adenosine-stress dynamic CTP and peak VO2 by cardiopulmonary exercise tests, and also assessed angina attack with Seattle Angina Questionnaire (SAQ).

Results

In the first protocol, CTP showed that adenosine-stress MBF was significantly decreased in the VSA group compared with the non-VSA group (VSA, 137.2±6.6 vs. Non-VSA, 174.4±10.7 ml/100g/min, P<0.01) (Figure B), although patient characteristics were comparable between the 2 groups. In the second protocol, exercise training was performed safely in all patients, and RCT showed that MBF was significantly increased in the Ex group compared with the non-Ex group (Figures C, D), although patient characteristics were also comparable between the 2 groups. Furthermore, peak VO2 was significantly increased in the Ex group compared with the non-Ex group (Figure E), and frequency of angina was significantly decreased in the Ex group compared with the non-Ex group (Figure F). Finally, there was a significant positive correlation between the extents of the changes in peak VO2 and the SAQ score for angina frequency in the Ex group (P<0.01, R=0.67).

Figures

Conclusions

These results provide the first evidence that vasodilator capacity of coronary microvessels is impaired in VSA patients, which can be ameliorated by exercise training.

Disappearance of Angiodysplasia Following Transcatheter Aortic Valve Implantation in a Patient with Heyde's Syndrome: A Case Report and Review of the Literature

An 83-year-old woman with severe aortic stenosis was admitted to our hospital due to heart failure with refractory anemia requiring blood transfusions. She had repetitive bleeding episodes from endoscopically proven angiodysplasia in the stomach. Moreover, she repeatedly underwent endoscopic argon plasma coagulation for hemostasis. Importantly, she had a deficiency of the high-molecular-weight (HMW) multimers of von Willebrand factor (VWF), and she was diagnosed with Heyde's syndrome.After she underwent transcatheter aortic valve implantation (TAVI), aortic valve area and mean left ventricular aorta pressure gradient improved. Notably, endoscopy showed cessation of bleeding at 10 days after TAVI and the disappearance of angiodysplasia at 4 months after TAVI. Even at 2 years after TAVI, follow-up endoscopy showed remaining free of angiodysplasia in the stomach. She experienced no episodes of anemia since TAVI procedure. Additionally, analysis of HMW multimers demonstrated immediate and lasting recovery after TAVI.Recovery of HMW multimers of VWF with cessation of gastrointestinal bleeding following aortic valve replacement has been previously reported in a patient diagnosed with Heyde's syndrome. To the best our knowledge, this is the first case to demonstrate that angiodysplasia disappears after TAVI for a long term with endoscopic images in a patient with Heyde's syndrome. Here, we summarized case reports of patients with Heyde's syndrome that required aortic valve intervention. Cessation of gastrointestinal bleeding and anemia after aortic valve intervention for severe aortic stenosis may be attributed not only to recovery of HMW multimers of VWF but also to the disappearance of angiodysplasia.

Coronary Adventitial and Perivascular Adipose Tissue Inflammation in Patients With Vasospastic Angina

BACKGROUND

Recent studies suggested that perivascular components, such as perivascular adipose tissue (PVAT) and adventitial vasa vasorum (VV), play an important role as a source of various inflammatory mediators in cardiovascular disease.

OBJECTIVES

The authors tested their hypothesis that coronary artery spasm is associated with perivascular inflammation in patients with vasospastic angina (VSA) using ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT).

METHODS

This study prospectively examined 27 consecutive VSA patients with acetylcholine-induced diffuse spasm in the left anterior descending artery (LAD) and 13 subjects with suspected angina but without organic coronary lesions or coronary spasm. Using CT coronary angiography and electrocardiogram-gated ¹⁸F-FDG PET/CT, coronary PVAT volume and coronary perivascular FDG uptake in the LAD were examined. In addition, adventitial VV formation in the LAD was examined with optical coherence tomography, and Rho-kinase activity was measured in circulating leukocytes.

RESULTS

Patient characteristics were comparable between the 2 groups. CT coronary angiography and ECG-gated ¹⁸F-FDG PET/CT showed that coronary PVAT volume and coronary perivascular FDG uptake significantly increased in the VSA group compared with the non-VSA group. Furthermore, optical coherence tomography showed that adventitial VV formation significantly increased in the VSA group compared with the non-VSA group, as did Rho-kinase activity. Importantly, during the follow-up period with medical treatment, both coronary perivascular FDG uptake and Rho-kinase activity significantly decreased in the VSA group.

CONCLUSIONS

These results provide the first evidence that coronary spasm is associated with inflammation of coronary adventitia and PVAT, where ¹⁸F-FDG PET/CT could be useful for disease activity assessment. (Morphological and Functional Change of Coronary Perivascular Adipose Tissue in Vasospastic Angina [ADIPO-VSA Trial]; UMIN000016675).

A case of pneumatosis intestinalis during neoadjuvant chemotherapy with cisplatin and 5-fluorouracil for esophageal cancer†

Pneumatosis intestinalis (PI) is a relatively rare disease. A 70-year-old man with stage II squamous cell carcinoma of the middle thoracic esophagus was administered cisplatin plus 5-fluorouracil (CF) therapy as neoadjuvant chemotherapy. On Day 14 of the first course of CF therapy, he complained of acute abdominal pain. Computed tomography (CT) revealed PI of the entire colon and a small air bubble in the mesentery. A colonoscopy revealed that there was no finding suggestive of ischemia. Because there was no sign of peritoneal irritation, conservative treatment was selected. On Day 7 after PI diagnosis, CT indicated the disappearance of PI. The patient underwent a radical esophagectomy. Intraoperative laparoscopic findings showed the serosa of the colon to be intact. The patient was discharged without any complications. It is important to take into account that CF therapy may cause PI and that PI can be treated conservatively.

Current Practices in Choosing Estimands and Sensitivity Analyses in Clinical Trials: Results of the ICH E9 Survey

BACKGROUND

An addendum to the International Conference on Harmonisation E9 (ICH E9) guidance document (Statistical Principles for Clinical Trials) is currently under development. The aim of the addendum is to promote harmonized standards on the choice of estimand (a well-defined measure of the treatment effect that is being estimated) in clinical trials and to describe a consensual framework for planning, conducting, and interpreting sensitivity analyses of clinical trial data.

METHODS

In order to help understand current practices relating to the choice of estimands and sensitivity analyses for clinical trials, the ICH E9 working group developing the addendum conducted a survey with a primary focus on clinical trials involving drugs, vaccines, and biologics. The survey was distributed electronically between May 19, 2015, and June 11, 2015, to various stakeholder groups within ICH, including industry, regulatory, and academic communities. A total of 1305 respondents participated.

RESULTS

Of the 1305 respondents 547 (42%), 344 (26%) and 283 (22%) were from Europe, USA and Japan respectively. Over half of the respondents work in pharmaceutical companies, and approximately a quarter of respondents noted oncology as the primary therapeutic area they work in. Over half of the respondents (595, 55%) noted the treatment effect being estimated was 'in the entire target population of patients regardless of whether they will take treatment as instructed'. The most common methods for handling missing data in primary analyses were mixed-models repeated measures (555, 56% respondents) and last observation carried forward (549, 55% respondents). The majority of respondents (816, 83%) noted they conducted sensitivity analyses to estimate treatment effects in different ways compared to the primary analysis by using alternative assumptions (627, 78%) and/or using alternative statistical methods (616, 76%).

CONCLUSIONS

The survey results have provided useful information to the ICH E9 working group on current practices on the choice of primary estimands for measuring treatment effects in confirmatory clinical trials, and approaches used to select sensitivity analyses.

Development of an optical time-resolved measurement system under high-pressure and low-temperature with a piston-cylinder pressure cell

To perform the femtosecond pump-probe spectroscopy under high pressure and low temperature, we constructed a measurement system with a piston cylinder type pressure cell installing an optical fiber bundle. The applied pressure was achieved to 6 kbar and the cell was cooled down to 15 K. Several demonstrations revealed that broadening and change of polarization of pulse (duration of ∼120 fs) owing to the dispersions in the fiber bundle are much small indicating that those have little influence on the measurement of carrier relaxation dynamics. In the measurements of κ-(BEDT-TTF)2Cu(NCS)2 under 1.3 kbar at 43 K, we have successfully detected the polarization anisotropy of the carrier relaxation dynamics and estimated the decay time in the same way as the normal measurement.

Mucinous carcinoma of the breast: a comparative study on cytohistological findings associated with neuroendocrine differentiation

OBJECTIVE

Mucinous carcinoma (MCA) may show neuroendocrine differentiation (ND), but the cytological features characteristic of ND remains elusive. We compared fine needle aspiration (FNA) findings of MCA between cases with high and low degrees of ND.

METHODS

Histological sections of 37 MCA cases were immunohistochemically evaluated for expression of chromogranin A and synaptophysin, and were graded as 0 to 3+ degrees of ND. They were divided into low ND (grade 0 and 1+) and high ND (grade 2+ and 3+) groups. Pre-operative FNA samples of each group were assessed for cytological features.

RESULTS

The mean age of the high ND group (n = 18) was higher than the low ND group (n = 19, P = 0.01). In FNA samples of the high ND group, 17 cases showed moderate to severe degrees of discohesiveness, but low ND cases mainly showed no or only mild discohesiveness (P < 0.001). Nine of the low ND cases displayed overlapped, cohesive cell clusters, whereas, in the high ND cases, the cells were arranged in a loose, flat and monolayered pattern (P = 0.045). Fourteen of the high ND cases had round nuclei, but oval nuclei were predominant in the low ND cases (P = 0.027). The nuclei were eccentrically located in 12 of the high ND cases but were centrally located in 14 of the low ND cases (P = 0.01).

CONCLUSIONS

Mucinous carcinoma with high ND may be diagnosed by the presence of discohesiveness, a flat, monolayered pattern, and round or eccentrically located nuclei. Features of ND in carcinomas in other organs, such as intracytoplasmic granules and coarse chromatin, may not be reliable cytological features of ND in MCA.

Deladenus nitobei n. sp. (Tylenchomorpha: Allantonematidae) isolated from Sirex nitobei (Hymenoptera: Siricidae) from Aomori, Japan, a new member of the siricidicola superspecies

Deladenus nitobein. sp., a parasite of a woodwasp species,Sirex nitobei, is described based on its typological characters and molecular profiles of part of the small subunit D2-D3 expansion segments of the large subunit and internal transcribed spacer region of the ribosomal RNA gene, as well as part of the mitochondrial cytochrome oxidase subunit I (mtCOI) gene. Adult host woodwasps emerging from dead Japanese red pine logs,Pinus densiflora, collected at Aomori, Japan, were dissected and examined for nematode association. The new species was isolated from the body cavity and reproductive system ofS. nitobeias large parasitic females and small parasitic juveniles. The nematodes were cultured successfully on 1.0% malt extract agar medium, inoculated withSirex-associated fungus,Amylostereumareolatum. The mycophagous adult nematodes were characterised by the relative position of the excretory pore, located at 25 (19-28) and 25 (18-30)μm anterior to the hemizonid in the male and female, respectively, and a broad female tail with a rounded distal end. Typologically, the new species forms a cryptic species complex withD. siricidicolaandD. canii. In addition, the new species andD. siricidicolashare the same host wasp, tree and fungal species in Japan. However, the cryptic species can be separated from each other based on the described morphological and molecular sequence differences in the mtCOI gene.

A novel leucine zipper motif-based hybrid peptide delivers a functional peptide cargo inside cells

We delivered a hybrid of an autophagy-inducing peptide and a cell-penetrating peptide via heterodimeric leucine zippers into the cell. By this method, the peptide successfully induced autophagy without significant cell death.

Magnetic anisotropy and interaction between f-electronic systems in dinuclear inverted-sandwich-type lanthanide-phthalocyanine complexes

The first detection and characterization of magnetic interaction between two 4f electronic systems in the dinuclear "inverted-sandwich-type" phthalocyanine complex with terbium ions and that of dysprosium ions are presented. Temperature dependent magnetic measurements for the diterbium complex, (μ-phthalocyaninato)bis[di(2,2,6,6-tetramethylheptane-3,5-dionato)terbium], show that the value of magnetic susceptibility times temperature, χT, sharply decreases as temperature is lowered, indicating the presence of an antiferromagnetic-type interaction between the Tb 3+ ions in the dinuclear complex. Similar temperature dependence was observed for the corresponding dinuclear dysprosium complex. These results are completely opposite to those observed for Pc triple-decker dinuclear terbium or dysprosium complexes, which are known to function as single molecule magnets. The NMR signals for the protons on the Pc ligand of the diterbium complex show up-field paramagnetic shifts due to the partially-filled 4f shells of the metal ions. This again makes sharp contrast to the triple-deckers, for which large down-field paramagnetic shifts are observed. These intriguing results seen in the NMR and magnetic susceptibility measurements are explained assuming the ligand field potential of the inverted-sandwich complexes gives strong easy-plain-type magnetic anisotropy, where Jz value of the lowest sublevel has a small value, while sandwich-type Pc3Ln2 ( Ln = Tb or Dy ) complexes have a strong easy-axis-type magnetic anisotropy.

Non-sarcomatous spindle cell morphology in conventional lung adenocarcinoma: a clinicopathological study

Non-sarcomatous spindle cell foci (N-SSCF) without aggressive invasiveness, also called morule-like lesions, occur occasionally in conventional lung adenocarcinoma, but their characteristics remain poorly understood. We identified N-SSCF in 7 (4.0 %) of 173 lung adenocarcinomas and examined their clinicopathological features. The patients were six men and one woman with a mean age of 57.0 years (range, 43-76 years). All tumors were papillary-predominant adenocarcinomas, ranging in size from 1 to 4.5 cm (mean, 2.7 cm). N-SSCF occupied 10-30 % of the tumors, and in all cases, there were focal or multifocal transitions between the two morphotypes. Most N-SSCF were plug-like nodules filling the spaces of cancerous alveoli/tubules or patchy insular nests. N-SSCF frequently contained mucin + lumina and were positive for cytokeratin 7, thyroid transcription factor 1, and Napsin A, but negative for cytokeratin 5/6 and vimentin, similar to the adenocarcinoma cells of the same tumor. Five cases (71 %) were at stage I or II, suggesting that N-SSCF can occur in an early phase of lung cancer. In an age-, sex-, and stage-matched control study, N-SSCF were not associated with prognosis (P = 0.471). We consider tumors with N-SSCF a distinct structural variant of adenocarcinoma without prognostic significance. They should be distinguished from true sarcomatous spindle cells and micropapillary components, which are associated with aggressive behavior.

Gapless quantum spin liquid in an organic spin-1/2 triangular-lattice κ-H3(Cat-EDT-TTF)2

We report the results of SQUID and torque magnetometry of an organic spin-1/2 triangular-lattice κ-H(3)(Cat-EDT-TTF)(2). Despite antiferromagnetic exchange coupling at 80-100 K, we observed no sign of antiferromagnetic order down to 50 mK owing to spin frustration on the triangular lattice. In addition, we found nearly temperature-independent susceptibility below 3 K associated with Pauli paramagnetism. These observations suggest the development of gapless quantum spin liquid as the ground state. On the basis of a comparative discussion, we point out that the gapless quantum spin liquid states in organic systems share a possible mechanism, namely the formation of a band with a Fermi surface possibly attributed to spinons.

Kosterlitz-Thouless-type transition in a charge ordered state of the layered organic conductor α-(BEDT-TTF)2I3

The current-voltage characteristics in the charge order state of the two-dimensional organic conductor α-(BEDT-TTF)(2)I(3) exhibit power law behavior at low temperatures. The power law is understood in terms of the electric-field-dependent potential between electrons and holes, which are thermally excited from the charge order state. The power law exponent steeply changes from 1 to 3 in the range from 30 to 45 K with decreasing temperature, thereby suggesting the occurrence of a Kosterlitz-Thouless-type transition; many (few) unbound electron-hole pairs are thermally excited above (below) the transition. The effects of the finite size and interlayer coupling on the power law behavior are discussed.