Comparison of novel DXA system, Shimazu SONIALVISION G4, with GE-Lunar PRODIGY.

INTRODUCTION: SONIALVISION G4 (Shimadzu, Kyoto, Japan) is a fluoroscopic imaging system capable of dual-energy X-ray absorptiometry (DXA) using the additional application. However, bone mineral density (BMD) with this system is calibrated only by a phantom, and the necessity to confirm the reliability of BMD measurement in human subjects has been pointed out. This study aimed to evaluate the clinical reliability of BMD measurement using SONIALVISION G4 by comparing it with PRODIGY (GE Healthcare, Madison, WI, USA), a reference system in developing the DXA application. MATERIALS AND METHODS: BMD measurements using these two DXA systems were performed on the same day at the lumbar spine and bilateral proximal femur of 130 subjects aged 22-86 years. The agreement and correlation between the measurements were determined. Thirty out of the 130 subjects were scanned twice to determine the precision of the SONIALVISION G4 system. RESULTS: BMD was highly correlated between the two DXA systems both at the lumbar spine and proximal femur, with correlation coefficients ranging from 0.963 (left total hip) to 0.989 (left femoral neck). Differences in BMD measured by the two systems were less than 3.0%, but a small proportional bias was observed in the Bland-Altman analysis. Coefficients of variation in BMD measurement were 1.77% in the lumbar spine and 1.41-2.76% in the proximal femur. CONCLUSIONS: Although BMD values by SONIALVISION G4 were close to those by PRODIGY, follow-up studies should be performed using the same device because of the small difference between devices.

Controlled growth of boron-doped epitaxial graphene by thermal decomposition of a B4C thin film.

We show that boron-doped epitaxial graphene can be successfully grown by thermal decomposition of a boron carbide thin film, which can also be epitaxially grown on a silicon carbide substrate. The interfaces of B4C on SiC and graphene on B4C had a fixed orientation relation, having a local stable structure with no dangling bonds. The first carbon layer on B4C acts as a buffer layer, and the overlaying carbon layers are graphene. Graphene on B4C was highly boron doped, and the hole concentration could be controlled over a wide range of 2 × 1013 to 2 × 1015 cm-2. Highly boron-doped graphene exhibited a spin-glass behavior, which suggests the presence of local antiferromagnetic ordering in the spin-frustration system. Thermal decomposition of carbides holds the promise of being a technique to obtain a new class of wafer-scale functional epitaxial graphene for various applications.

Gatekeeping in an inpatient rehabilitation facility to reduce morbidity and mortality due to cardiac disease: screening program using of BNP and ECG Auto-diagnosis.

The Kaifukuki-Rehabilitation Ward (KRW) is a type of inpatient rehabilitation facility in Japan. In the KRW of our institute, mortality and frequency of emergency referrals in 2013 were rather high, 2.6% and 4.3%, respectively. We aimed to investigate the usefulness of an original gatekeeping system to reduce mortality and morbidity from cardiac complications, and to improve the quality of medical care in the KRW. A total of 370 consecutive patients admitted to the KRW of Kobayashi Memorial Hospital between 1 May 2015 and 31 March 2016 were enrolled in this prospective observational study. All patients underwent a screening evaluation in which we defined patients as being screen positive (SC-positive) if they had at least one of 20 diagnostic ECG codes and/or BNP level over 140 pg/dL at admission. A cardiologist provided weekly interventions to those among SC-positive patients who needed cardiac disease treatment during hospitalization. In all, 129 patients were classified as SC-positive (mean age 80 years, 124 [32%] male), and weekly intervention was needed in 28 patients, including start of cardiac medication in 17 cases. Mortality and frequency of emergency transfer due to cardiac disease during hospital stay were 0.3% and 0.3%, respectively. Our gatekeeping system involving a screening evaluation at admission and weekly intervention in selected patients by a cardiologist may be useful in reducing mortality and rate of transfer due to cardiac disease and may improve quality of medical care in KRWs.

A Multidisciplinary Approach to the Management of Chronic Pain through a Self-managed Behavioral Exercise Program : A Pilot Study in Japan.

We conducted this study to determine the short-term treatment outcomes of multidisciplinary approaches to chronic pain management for outpatients in Japan. We evaluated pain reduction and improvement in quality of life (QOL) after treatment. We analyzed 32 patients who had experienced intractable chronic pain for > 3 months. The patients received multidisciplinary therapeutic self-managed exercise instructions and then underwent evaluations 1 and 3 months after the treatment. We used the Pain Disability Short Form-36 (SF-36), Pain Catastrophizing Scale (PCS), and Pain Disability Assessment Scale (PDAS) to evaluate QOL. Although the pain levels were the same before and after the physical exercise program, the patients showed significant improvements in physical function on the SF-36 (48.5 vs. 54.5, 3 months vs. 1 month; p=0.0124), the magnification subscale on the PCS (6.8 vs. 5.9, 1 month vs. before; p=0.0164) and the PDAS (29.2 vs. 23.4, 3 months vs. before; p=0.0055). Chronic pain should be treated with a biopsychosocial approach, but time constraints and costs have limited the implementation of multidisciplinary and behavioral approaches to chronic pain management. Our findings demonstrate that clinical improvements are possible for patients with chronic pain, using multidisciplinary team resources widely available in Japanese clinical practice.

Phase IIb, Randomized, Double-Blind, Placebo-Controlled Study of Naldemedine for the Treatment of Opioid-Induced Constipation in Patients With Cancer.

Purpose This randomized, double-blind, multicenter study aimed to determine the dose of naldemedine, a peripherally-acting µ-opioid receptor antagonist, for future trials by comparing the efficacy and safety of three doses of naldemedine versus placebo in patients with cancer and opioid-induced constipation. Methods Patients ≥ 18 years old with cancer, an Eastern Cooperative Oncology Group performance status ≤ 2, who had been receiving a stable regimen of opioid analgesics for ≥ 2 weeks, had at least one constipation symptom despite laxative use, and no more than five spontaneous bowel movements (SBMs) during the past 14 days, were randomly assigned (1:1:1:1) to oral, once-daily naldemedine 0.1, 0.2, or 0.4 mg, or placebo, for 14 days. The primary end point was change in SBM frequency per week from baseline during the treatment period. Secondary end points included SBM responder rates, change from baseline in the frequency of SBM without straining, and complete SBM. Safety was also assessed. Results Of 227 patients who were randomly assigned, 225 were assessed for efficacy (naldemedine 0.1 mg, n = 55; 0.2 mg, n = 58; 0.4 mg, n = 56; placebo, n = 56) and 226 for safety. Change in SBM frequency (primary end point) was higher with all naldemedine doses versus placebo ( P < .05 for all comparisons), as were SBM responder rates and change in complete SBM frequency. Change in SBM frequency without straining was significantly improved with naldemedine 0.2 and 0.4 (but not 0.1) mg versus placebo (at least P < .05). Treatment-emergent adverse events were more common with naldemedine (0.1 mg: 66.1%; 0.2 mg: 67.2%; 0.4 mg: 78.6%) than placebo (51.8%); the most common treatment-emergent adverse event was diarrhea. Conclusion Fourteen-day treatment with naldemedine significantly improved opioid-induced constipation in patients with cancer and was generally well tolerated. Naldemedine 0.2 mg was selected for phase III studies.

Discovery of 3-Chloro-N-{(S)-[3-(1-ethyl-1H-pyrazol-4-yl)phenyl][(2S)-piperidine-2-yl]methyl}-4-(trifluoromethyl)pyridine-2-carboxamide as a Potent Glycine Transporter 1 Inhibitor.

A novel glycine transporter 1 (GlyT1) inhibitor was designed by the superposition of different chemotypes to enhance its inhibitory activity. Starting from 2-chloro-N-{(S)-phenyl[(2S)-piperidin-2-yl]methyl}-3-(trifluoromethyl)benzamide (2, SSR504734), the introduction of heteroaromatic rings enabled an increase in the GlyT1 inhibitory activity. Subsequent optimization led to the identification of 3-chloro-N-{(S)-[3-(1-ethyl-1H-pyrazol-4-yl)phenyl][(2S)-piperidine-2-yl]methyl}-4-(trifluoromethyl)pyridine-2-carboxamide (7w), which showed a powerful GlyT1 inhibitory activity (IC50=1.8 nM), good plasma exposure and a plasma to brain penetration in rats that was sufficient to evaluate the compound's pharmacological properties. Compound 7w showed significant effects in several rodent models for schizophrenia without causing any undesirable central nervous system side effects.

Design and synthesis of 1H-pyrazolo[3,4-c]pyridine derivatives as a novel structural class of potent GPR119 agonists.

Design and synthesis of a novel class of 1H-pyrazolo[3,4-c]pyridine GPR119 receptor agonists are described. Lead compound 4 was identified through the ligand-based drug design approach. Modification of the left-hand aryl group (R(1)) and right-hand piperidine N-capping group (R(2)) led to the identification of compound 24 as a single-digit nanomolar GPR119 agonist.

Angiosarcoma arising in the non-operated, sclerosing breast after primary irradiation, surviving 6 years post-resection: A case report and review of the Japanese literature.

INTRODUCTION: Angiosarcoma consists only 0.04% of all breast malignancies and has a poor prognosis. This is the first reported case of an angiosarcoma arising in the non-operated breast after primary irradiation for occult breast cancer. The patient underwent mastectomy, surviving disease free for 6 years. PRESENTATION OF CASE: A 73-year-old woman with a past history of irradiation of the non-operated left breast complained of skin thickening and crust formation on the left nipple 8 years post-irradiation. Considering the clinical history and radiological studies, recurrent cancer was suspected and biopsy was performed. However, no proof of malignancy was obtained. As clinical symptoms continued to advance, informed consent was obtained and mastectomy was performed. Histological examination of the surgical specimen revealed angiosarcoma. DISCUSSION: In this case, angiosarcoma occurred after radiation on a non-operated breast. Preoperative diagnosis was not achieved even with two cytology specimen and one biopsy. Each showed only fibrosis and inflammatory changes. The background breast tissue inflammation should have been caused by radiation. Marked fibrosis and the rather small number of sarcoma cells in the breast tumor in this case may be why bioptic diagnosis was difficult. Kaplan-Meier analysis of 60 Japanese breast angiosarcoma patients showed significantly better prognosis in patients with a tumor 2cm or smaller. CONCLUSION: Angiosarcoma may occur in the non-operated breast, post irradiation. The potential difficulties of diagnosing angiosarcoma against background fibrosis should be kept in mind. Initial radical surgery currently represents the only effective treatment for improving survival in these patients.

[Switching from oral oxycodone to oxycodone injection - an investigation into the dosage amount ratio].

In switching from oraloxycodone to oxycodone injection, clinical guidelines recommend a conversion dose ratio of 0.75. However, in clinical sites, a higher dosage may be needed due to characteristics of cancer pain. In the present study, we investigated changing the dosage amount of oxycodone before and after switching from oraloxycodone administration to oxycodone injection in patients (n=14) who reported suffering from cancer pain. As a result, we found the ratio of the amount used after switching to be 0.91 ± 0.25 (mean ± SD) on the first day, increasing to 1.46 ± 0.48 on the fifth day. Our findings suggest that the dosage amount was the correct one for each patient's condition and also that adequate injection dosage to manage cancer pain was greater than that of calculated by the conversion ratio.

Physicochemical origin of high correlation between thermal stability of a protein and its packing efficiency: a theoretical study for staphylococcal nuclease mutants.

There is an empirical rule that the thermal stability of a protein is related to the packing efficiency or core volume of the folded state and the protein tends to exhibit higher stability as the backbone and side chains are more closely packed. Previously, the wild type and its nine mutants of staphylococcal nuclease were compared by examining their folded structures. The results obtained were as follows: The stability was not correlated with the number of intramolecular hydrogen bonds, intramolecular electrostatic interaction energy, or degree of burial of the hydrophobic surface; though the empirical rule mentioned above held, it was not the proximate cause of higher stability; and the number of van der Waals contacts N vdW, or equivalently, the intramolecular van der Waals interaction energy was an important factor governing the stability. Here we revisit the wild type and its nine mutants of staphylococcal nuclease using our statistical-mechanical theory for hydration of a protein. A molecular model is employed for water. We show that the pivotal factor is the magnitude of the water-entropy gain upon folding. The gain originates from an increase in the total volume available to the translational displacement of water molecules coexisting with the protein in the system. The magnitude is highly correlated with the denaturation temperature T m. Moreover, the apparent correlation between N vdW and T m as well as the empirical rule is interpretable (i.e., their physicochemical meanings can be clarified) on the basis of the water-entropy effect.

Left frontal lobe hypoperfusion and depressive symptoms in Alzheimer's disease patients taking cholinesterase inhibitors.

Depressive symptoms are common in patients with Alzheimer's disease (AD) and increase the caregiver burden. Many studies have reported dorsolateral prefrontal hypometabolism or hypoperfusion in AD patients with depressive symptoms, most of whom did not take acetylcholinesterase inhibitors (AChEI). It is not clear, however, whether a similar condition is present in patients taking AChEI medication. Fifty-seven consecutive AD patients taking AChEI were recruited at a memory clinic. Objective depressive symptoms were evaluated using the depression domain of the Neuropsychiatric Inventory (NPI-dep). All patients underwent brain single photon emission computed tomography (SPECT) with (99m)Tc-ethylcysteinate dimer, and the SPECT images were analyzed using the Statistical Parametric Mapping 8 program. No significant differences between groups with positive and negative NPI-dep scores were found with respect to age, sex, years of education, and cognitive function. Compared with patients with negative NPI-dep scores, patients with NPI-dep scores ≥1 showed significant hypoperfusion in the left middle frontal region. Our results indicate that the dorsolateral prefrontal area is significantly involved in the pathogenesis of depressive symptoms in AD patients being treated with AChEI. The area on the left side especially may be closely related to the depressive symptoms evaluated using the NPI.

Multidisciplinary management of small cell carcinoma of the breast: a case report.

We report a case of primary small cell carcinoma (SCC) of the breast in a 59-year-old female. To the best of our knowledge, there are only 44 cases of this disease reported in the English literature. The patient also had regional nodal metastases, but no distant metastases. She underwent neoadjuvant chemotherapy according to a regimen of pulmonary SCC, and combination of cisplatin and etoposide (CDDP+VP16). The tumor partially responded to neoadjuvant chemotherapy. The treatment was followed by modified radical mastectomy and adjuvant chemotherapy, i.e., EC therapy (epirubicin and cyclophosphamide). She was also administered in total 50 Gy of radiation treatment to the chest wall. At this writing, the patient has evidenced no recurrence 36 months after her diagnosis.

Subanalgesic ketamine enhances morphine-induced antinociceptive activity without cortical dysfunction in rats.

PURPOSE: Ketamine, a noncompetitive N-methyl-D-aspartate receptor antagonist, has been used for the treatment of cancer pain as an analgesic adjuvant to opioids. However, ketamine is known to produce psychotomimetic side effects including cognitive impairments under a high-dose situation, presumably as the result of cortical dysfunction. Here, we investigated whether low-dose ketamine was useful as an analgesic adjuvant to morphine for pain control, focusing on frontocortical function. METHODS: To assess the analgesic effects of ketamine with or without morphine, we performed behavioral and histochemical experiments, using the hot plate test and c-Fos expression analysis in rats. The effect on cortical function was also determined by prepulse inhibition (PPI) of the acoustic startle and evoked potentials in the hippocampal CA1-medial prefrontal cortex (mPFC) synapses as measures of synaptic efficacy. RESULTS: Coadministration of ketamine as a subanalgesic dose significantly enhanced intraperitoneal morphine-induced antinociceptive response, which was measured as the increased reaction latency in the hot plate test. In addition, the noxious thermal stimulus-induced c-Fos expression in the ventrolateral periaqueductal gray matter was significantly suppressed by concomitant ketamine and morphine. In contrast, the subanalgesic dose of ketamine did not impair PPI and synaptic efficacy in the mPFC. CONCLUSION: The present results indicate that the morphine-induced analgesic effect is enhanced by a concomitant subanalgesic dose of ketamine without affecting cortical function. Our findings possibly support the clinical notion that low-dose ketamine as an analgesic adjuvant has therapeutic potential to reduce opioid dosage, thereby improving the quality of life in cancer pain patients.

An awareness survey of surgeons involved in breast cancer treatment regarding their patients returning to work.

Surgeons focus on the period of absence from work during the initial treatment of breast cancer. The aim of this study was to determine surgeons' perceptions and awareness regarding the necessary period of absence from work during breast cancer treatment. We created a questionnaire for all surgeons involved in breast cancer treatment who are affiliated with the Department of Surgery at the Nagoya University Graduate School of Medicine and its associated facilities. The necessary leave of absence period for each treatment was considered, and the decision regarding whether patients should return to work was examined. The surgeons were instructed to assume that a 'heavy load worker' was a nurse or caregiver and that a 'light load worker' was a medical office worker. This study included 184 surgeons (response rate: 96.8%). More than half of the surgeons considered that light load workers could return to work within 2 weeks; 89.8% after conservative resection, 71.6% after total mastectomy, 50.3% after axillary dissection. In contrast, more than half of the surgeons considered that heavy load worker should wait returning to work more than 3 weeks; 49.4% after conservative resection, 73.3% after total mastectomy, 85.7% after axillary dissection. For patients treated with chemotherapy, three-quarters of the surgeons indicated that it would be difficult to work while receiving anthracycline regimens. The results suggest that surgeons can predict the approximate period of absence from work for patients who receive an initial treatment of breast cancer.

Hydrogen-driven asymmetric reduction of hydroxyacetone to (R)-1,2-propanediol by Ralstonia eutropha transformant expressing alcohol dehydrogenase from Kluyveromyces lactis.

BACKGROUND: Conversion of industrial processes to more nature-friendly modes is a crucial subject for achieving sustainable development. Utilization of hydrogen-oxidation reactions by hydrogenase as a driving force of bioprocess reaction can be an environmentally ideal method because the reaction creates no pollutants. We expressed NAD-dependent alcohol dehydrogenase from Kluyveromyces lactis in a hydrogen-oxidizing bacterium: Ralstonia eutropha. This is the first report of hydrogen-driven in vivo coupling reaction of the alcohol dehydrogenase and indigenous soluble NAD-reducing hydrogenase. Asymmetric reduction of hydroxyacetone to (R)-1,2-propanediol, which is a commercial building block for antibacterial agents, was performed using the transformant as the microbial cell catalyst. RESULTS: The two enzymes coupled in vitro in vials without a marked decrease of reactivity during the 20 hr reaction because of the hydrogenase reaction, which generates no by-product that affects enzymes. Alcohol dehydrogenase was expressed functionally in R. eutropha in an activity level equivalent to that of indigenous NAD-reducing hydrogenase under the hydrogenase promoter. The hydrogen-driven in vivo coupling reaction proceeded only by the transformant cell without exogenous addition of a cofactor. The decrease of reaction velocity at higher concentration of hydroxyacetone was markedly reduced by application of an in vivo coupling system. Production of (R)-1,2-propanediol (99.8% e.e.) reached 67.7 g/l in 76 hr with almost a constant rate using a jar fermenter. The reaction velocity under 10% PH2 was almost equivalent to that under 100% hydrogen, indicating the availability of crude hydrogen gas from various sources. The in vivo coupling system enabled cell-recycling as catalysts. CONCLUSIONS: Asymmetric reduction of hydroxyacetone by a coupling reaction of the two enzymes continued in both in vitro and in vivo systems in the presence of hydrogen. The in vivo reaction system using R. eutropha transformant expressing heterologous alcohol dehydrogenase showed advantages for practical usage relative to the in vitro coupling system. The results suggest a hopeful perspective of the hydrogen-driven bioprocess as an environmentally outstanding method to achieve industrial green innovation. Hydrogen-oxidizing bacteria can be useful hosts for the development of hydrogen-driven microbial cell factories.

Postoperative function following radical surgery in gastric and colorectal cancer patients over 80 years of age--an objection to "ageism".

PURPOSE: With rapid growth in the elderly population, the number of elderly cancer patients who should be offered life-prolonging radical surgery has been increasing. The aim of this report is to demonstrate the outcome of elective radical surgery for gastric or colorectal cancer patients 80 years of age or older, including the natural course of recovery of functional independence, in order to avoid the negative attitude held toward surgery that is due only to patients' high chronological age. METHODS: Physical condition, ADL, and QOL of 108 patients 80 years of age or older with gastric or colorectal cancer were evaluated preoperatively and at the 1st, 3rd, and 6th postoperative months. RESULTS: There were no operative deaths, and the morbidity rate was 27.9%. Only 6% of the patients showed a decrease in ADL at the 6th postoperative month. This decrease typically occurred following discharge from the hospital. Patient QOL showed recovery to an extent equal to or better than average preoperative scores. CONCLUSIONS: Of the patients who underwent elective surgery for gastric or colorectal cancer, only a few showed a protracted decline in ADL, and most exhibited better QOL after surgery. Surgical treatment should therefore be considered, whenever needed, for elderly patients 80 years of age or older with gastric or colorectal cancer.

Chronic heavy metal exposure and gallbladder cancer risk in India, a comparative study with Japan.

BACKGROUND: High incidence of gallbladder cancer (GBC) is reported from North India, with elevated concentrations of heavy metals in water and soil. This Indo-Japan collaborative study compared presence of heavy metals in gallbladder tissues. METHODS: Heavy metal concentrations were estimated in Indian GBC and cholecystitis tissues and compared with Japanese GBC and cholecystitis tissues. Spectrophotometry was done for 13 Indian gallbladder tissues (8 GBC, 5 cholecystitis) and 9 Japanese (5 GBC, 4 cholecystitis). Transmission electron microscopy (TEM) thin foil element analysis was done in 10 Indian samples (6 GBC, 4 cholecystitis). RESULTS: Chromium, lead, arsenic and zinc were significantly high in Indian GBC compared with Japanese GBC. Chromium, lead and arsenic were significantly high in the Indian cholecystitis tissues compared to the Japanese. TEM of Indian tissues demonstrated electron dense deposits in GBC. CONCLUSION: Heavy metals- chromium, lead, arsenic and zinc are potential carcinogens in Indian GBC from endemic areas. This preliminary study links presence of heavy metals in gallbladder cancer tissues in endemic areas.

Free-energy function for discriminating the native fold of a protein from misfolded decoys.

In this study, free-energy function (FEF) for discriminating the native fold of a protein from misfolded decoys was investigated. It is a physics-based function using an all-atom model, which comprises the hydration entropy (HE) and the total dehydration penalty (TDP). The HE is calculated using a hybrid of a statistical-mechanical theory applied to a molecular model for water and the morphometric approach. The energetic component is suitably taken into account in a simple manner as the TDP. On the basis of the results from a careful test of the FEF, which have been performed for 118 proteins in representative decoy sets, we show that its performance is distinctly superior to that of any other function. The FEF varies largely from model to model for the candidate models for the native structure (NS) obtained from nuclear magnetic resonance experiments, but we can find models or a model for which the FEF becomes lower than for any of the decoy structures. A decoy set is not suited to the test of a free-energy or potential function in cases where a protein isolated from a protein complex is considered and the structure in the complex is used as the model NS of the isolated protein without any change or where portions of the terminus sides of a protein are removed and the percentage of the secondary structures lost due to the removal is significantly high. As these findings are made possible, we can assume that our FEF precisely captures the features of the true NS.

[A case of spindle cell carcinoma of the breast, in which irinotecan was effective against respiratory failure due to pulmonary metastases].

We present our experience with chemotherapy using irinotecan for lung metastases of spindle cell carcinoma of the breast. The patient is a 50-year-old female, who consulted our hospital due to a large breast tumor about 7 cm in diameter. Although computed tomography revealed invasion to the chest wall, no distant metastases were confirmed. Chemotherapy (FEC100 followed by paclitaxel) was not effective for down-staging. To improve her quality of life, standard radical mastectomy with combined partial resection of the chest wall was performed. The tumor was histologically diagnosed as spindle cell carcinoma. After the operation, multiple lung metastases appeared, and she had severe dyspnea. Thereafter irinotecan was administered. One week after the administration, metastatic lesions were reduced so that her dyspnea was remarkably relieved. The patient continued to receive irinotecan weekly until she died on the 49th day of treatment with irinotecan.

Effects of heme on the thermal stability of mesophilic and thermophilic cytochromes c: comparison between experimental and theoretical results.

We have recently proposed a measure of the thermal stability of a protein: the water-entropy gain at 25 °C upon folding normalized by the number of residues, which is calculated using a hybrid of the angle-dependent integral equation theory combined with the multipolar water model and the morphometric approach. A protein with a larger value of the measure is thermally more stable. Here we extend the study to analyses on the effects of heme on the thermal stability of four cytochromes c (PA c(551), PH c(552), HT c(552), and AA c(555)) whose denaturation temperatures are considerably different from one another despite that they share significantly high sequence homology and similar three-dimensional folds. The major conclusions are as follows. For all the four cytochromes c, the thermal stability is largely enhanced by the heme binding in terms of the water entropy. For the holo states, the measure is the largest for AA c(555). However, AA c(555) has the lowest packing efficiency of heme and the apo polypeptide with hololike structure, which is unfavorable for the water entropy. The highest stability of AA c(555) is ascribed primarily to the highest efficiency of side-chain packing of the apo polypeptide itself. We argue for all the four cytochromes c that due to covalent heme linkages, the number of accessible conformations of the denatured state is decreased by the steric hindrance of heme, and the conformational-entropy loss upon folding becomes smaller, leading to an enhancement of the thermal stability. As for the apo state modeled as the native structure whose heme is removed, AA c(555) has a much larger value of the measure than the other three. Overall, the theoretical results are quite consistent with the experimental observations (e.g., at 25 °C the α-helix content of the apo state of AA c(555) is almost equal to that of the holo state while almost all helices are collapsed in the apo states of PA c(551), PH c(552), and HT c(552)).