[INVESTIGATION OF THE IMPACT OF ALLERGIC DISEASE ON CHILDREN'S SARS-CoV-2 VACCINATION DECISIONS].

Background, Objectives: The factors associated with parents' decisions to vaccinate their children with SARS-CoV-2 vaccine and the impact of the coexistence of allergic diseases in their children are unclear. METHODS: A cross-sectional survey was conducted among parents of patients aged 15 years or younger who visited our pediatric allergy outpatient clinic and three partner pediatric clinics between April and May 2021. Survey items included presence or absence of other allergic diseases, and SARS-CoV-2 vaccination preferences and reasons. RESULTS: 646 responses were received, with 568 valid responses (88%). Thirty-eight respondents (6.7%) did not want their children to receive SARS-CoV-2 vaccine. Factors that led parents to reject the SARS-CoV-2 vaccine for their children were the coexistence of food allergies and a low evaluation of the expectations of the safety and preventive effect of the SARS-CoV-2 vaccine. The top reasons for not wanting to vaccinate were related to concerns about side effects to the vaccine. CONCLUSION: In order for parents to make correct decisions regarding SARS-CoV-2 vaccination of their children, it is necessary to create an environment in which up-to-date and correct information is available to avoid excessive anxiety. More care is needed, especially if the child has food allergies.

The Incidence of Para-Anastomotic Aneurysm After Open Repair Surgery for Abdominal Aortic Aneurysm Through Routine Annual Computed Tomography Imaging.

OBJECTIVE: Open repair surgery (ORS) for an abdominal aortic aneurysm (AAA) remains an important treatment option, but the incidence of para-anastomotic aneurysms is unclear. The purpose of this study was to estimate the incidence of para-anastomotic aneurysms and reveal secondary complications through routine annual computed tomography (CT) imaging. METHODS: One hundred and forty-seven patients who underwent ORS for AAA between January 2006 and December 2015 and received routine CT imaging surveillance were enrolled. RESULTS: The follow up period was 7.1 ± 2.7 years. The total follow up time of all patients was 1 041.1 years, and 958 CT images were collected (0.92 CT scans/year/patient). A proximal para-anastomotic aneurysm was detected in five patients (3.4%). Four of the five patients had aneurysmal dilation at the initial ORS (proximal diameter >25 mm), which enlarged during follow up; thus, a de novo proximal para-anastomotic aneurysm was observed in one patient (0.7%). The time between surgery and the diagnosis of all proximal para-anastomotic aneurysms was 5.7 ± 1.4 years, and the de novo proximal para-anastomotic aneurysm was detected at 11.8 years. The incidence of all para-anastomotic aneurysms at five and 10 years was 2.2% and 3.6%, and the incidence of the de novo para-anastomotic aneurysm was 0% at five and 10 years. Nine synchronous thoracic aortic aneurysms (TAAs) and seven metachronous TAAs were detected, and 16 patients (10.9%) had a TAA. Neoplasms were detected in 18 of 147 patients (12.2%), and the most dominant neoplasm was lung cancer. CONCLUSION: The incidence of para-anastomotic aneurysms was low; thus, abdominal and pelvic CT imaging every five years may be sufficient and consistent with the current AAA guidelines. In contrast, TAAs were diagnosed in a high percentage of patients, and based on these observations, routine CT imaging should be expanded to include the chest.

[Aortic Root Pseudoaneurysm due to Avulsion of Aortic Valve Commissure Following to Infective Endocarditis;Report of a case].

A 40-year-old man presented to our hospital with fever and slight palpitation. The echocardiogram revealed bicuspid aortic valve, massive aortic regurgitation, and aneurysm of Valsalva sinus. Operative findings showed an aortic root pseudoaneurysm originating just below the avulsion of the right to left commissure. The orifice was closed with a part of a woven vascular graft, and the aortic valve was replaced with a mechanical valve. There was no sign of marked inflammation, although pathophysiologic findings indicated infective endocarditis. His postoperative course was uneventful.

Gene Expression Profiling of IL-17A-Treated Synovial Fibroblasts from the Human Temporomandibular Joint.

Synovial fibroblasts contribute to the inflammatory temporomandibular joint under pathogenic stimuli. Synovial fibroblasts and T cells participate in the perpetuation of joint inflammation in a mutual activation feedback, via secretion of cytokines and chemokines that stimulate each other. IL-17 is an inflammatory cytokine produced primarily by Th17 cells which plays critical role in the pathogenesis of numerous autoimmune and inflammatory diseases. Here, we investigated the roles of IL-17A in temporomandibular joint disorders (TMD) using genome-wide analysis of synovial fibroblasts isolated from patients with TMD. IL-17 receptors were expressed in synovial fibroblasts as assessed using real-time PCR. Microarray analysis indicated that IL-17A treatment of synovial fibroblasts upregulated the expression of IL-6 and chemokines. Real-time PCR analysis showed that the gene expression of IL-6, CXCL1, IL-8, and CCL20 was significantly higher in IL-17A-treated synovial fibroblasts compared to nontreated controls. IL-6 protein production was increased by IL-17A in a time- and a dose-dependent manner. Additionally, IL-17A simulated IL-6 protein production in synovial fibroblasts samples isolated from three patients. Furthermore, signal inhibitor experiments indicated that IL-17-mediated induction of IL-6 was transduced via activation of NFκB and phosphatidylinositol 3-kinase/Akt. These results suggest that IL-17A is associated with the inflammatory progression of TMD.

[Leg amputation for severe lower limb ischemia caused by type A acute aortic dissection; report of a case].

A 41-year-old man underwent total arch replacement and aorto-bifemoral bypass owing to type A acute aortic dissection complicated by ischemia of both lower extremities. Just after the operation, he developed myonephropathic metabolic syndrome due to severe ischemia of the right leg, and hemodiafiltration was performed. However, the serum potassium was elevated to an uncontrollable level. Ligation of the right femoral artery and the right branch of the bypass graft was performed one hour after the transfer to intensive care unit (ICU), and the serum potassium dropped to a normal level. He underwent amputation of the right lower limb above the knee on the 13th postoperative day, and was discharged after long-term rehabilitation.

Surgical treatment for an asymptomatic and unruptured sinus of Valsalva aneurysm: report of a case.

A 70-year-old male underwent a transthoracic echocardiography as a screening test for hypertension and an unruptured aneurysm was detected in the right sinus of Valsalva. The right sinus of Valsalva aneurysm obstructed the right ventricle outflow tract but he did not have any symptoms. The sinus of Valsalva aneurysm was treated successfully by a patch closure with a bovine pericardial patch.

[Susceptibilities of bacteria isolated from patients with lower respiratory infectious diseases to antibiotics (2006)].

From October 2006 to September 2007, we collected the specimen from 356 patients with lower respiratory tract infections in 14 institutions in Japan, and investigated the susceptibilities of isolated bacteria to various antibacterial agents and patients' characteristics. Of 414 strains that were isolated from specimen (mainly from sputum) and assumed to be bacteria causing in infection, 407 strains were examined. The isolated bacteria were: Staphylococcus aureus 64, Streptococcus pneumoniae 96, Haemophilus influenzae 87, Pseudomonas aeruginosa (non-mucoid) 52, P. aeruginosa (mucoid) 11, Klebsiella pneumoniae 20, and Moraxella catarrhalis 44. Of 64 S. aureus strains, those with 2 microg/ml or less of MIC of oxacillin (methicillin-susceptible S. aureus: MSSA) and those with 4 microg/ml or more of MIC of oxacillin (methicillin-resistant S. aureus: MRSA) were 27 (42.2%) and 37 (57.8%) strains, respectively. Against MSSA, imipenem had the most potent antibacterial activity and inhibited the growth of all strains at 0.063 microg/ml or less. Against MRSA, vancomycin and linezolid showed the most potent activity and inhibited the growth of all the strains at 1 microg/ml. Carbapenems showed the most potent activities against S. pneumoniae and in particular, panipenem inhibited the growth of all the strains at 0.063 microg/ml or less. Imipenem and faropenem also had a preferable activity and inhibited the growth of all the strains at 0.125 and 0.5 microg/ml, respectively. In contrast, there were high-resistant strains (MIC: over 128 microg/ml) for erythromycin (45.8%) and clindamycin (20.8%). Against H. influenzae, levofloxacin showed the most potent activity and its MIC90 was 0.063 microg/ml or less. Meropenem showed the most potent activity against P. aeruginosa (mucoid) and its MIC90 was 0.5 microg/ml. Against P. aeruginosa (non-mucoid), tobramycin had the most potent activity and its MIC90 was 2 microg/ml. Against K. pneumoniae, cefozopran was the most potent activity and inhibited the growth of all the strains at 0.063 microg/ml or less. Also, all the antibacterial agents except ampicillin generally showed a potent activity against M. catarrhalis and the MIC90 of them were 2 microg/ml or less. The approximately half the number (50.6%) of the patients with respiratory infection were aged 70 years or older. Bacterial pneumonia and chronic bronchitis accounted for 49.2% and 28.1% of all the respiratory infections, respectively. The bacteria frequently isolated from the patients with bacterial pneumonia were S. pneumoniae (29.2%), S. aureus (20.8%), and H. influenzae (12.9%). H. influenzae (25.0%) and P. aeruginosa (21.7%) also were frequently isolated from the patients with chronic bronchitis. Before the antibacterial agent administration, the bacteria frequently isolated from the patients were S. pneumoniae (27.5%) and H. influenzae (22.5%). The bacteria frequently isolated from the patients treated with macrolides was P. aeruginosa, and its isolation frequently was 39.4%.

[The effects of Trans Pacific Partnership (TPP) for Japanese medical system].

The effects of Trans Pacific Partnership (TPP) for Japanese medical system were analyzed concretely. TPP has a great influence on the Japanese medical system, although, it was supposed that most of them would be capable to resolve except kaihoken: health insurance for all.

The effects of hydroxyethyl starch 130/0.4 on perioperative renal function in patients undergoing cardiac surgery: A randomised controlled trial.

Background: Acute kidney injury (AKI) after cardiac surgery increases the risk of morbidity and mortality. Hydroxyethyl starch (HES) is often used during surgery due to its plasma-volume expanding effect, but the impact of HES 130/0.4 on renal function in patients undergoing cardiac surgery remains unclear. The aim of our study is to investigate the impact of HES 130/0.4 on postoperative renal function in patients undergoing cardiac surgery using cardiopulmonary bypass. Methods: Our study was a randomised, single-center, single-blind study conducted on 60 adult patients who underwent cardiac surgery using cardiopulmonary bypass: 30 patients were intraoperatively administered with HES 130/0.4; the other 30 with Ringer's bicarbonate. The primary endpoints were occurrence of AKI within 30 days of surgery and the disease stages. Results: The mean dose of 6% HES 130/0.4 was 28 ml/kg. AKI occurred within 30 days of the operation in 8 cases (28.6%) in the HES group and 6 cases (21.4%) in the crystalloid group (no significance: p = 0.5371). Disease stages were as follows: "no AKI", "stage 1", "stage 2″ and "stage 3″, accounting for 20 cases (71.5%), 6 cases (21,4%), 2 cases (7.1%), and 0 cases, respectively, in the HES group, and 22 cases (78.6%), 6 cases (21.4%), 0 cases, and 0 cases, respectively, in the crystalloid group (no significance: p = 0.3508). Conclusion: There was no significant difference in the occurrences or stages of AKI during the 30 days following cardiac surgery with cardiopulmonary bypass between patients administered with HES 130/0.4 or Ringer's bicarbonate.

Pediatric Pure Red Cell Aplasia Caused by Tacrolimus After Living-Donor Liver Transplant.

Pure red cell aplasia is a relatively rare disease characterized by selective suppression of erythroid precursors in the bone marrow. This disease can also develop secondary to several other diseases and as a side effect of certain drugs. Tacrolimus, a potent immunosuppressant, is widely used in organ transplant. Several cases of pure red cell aplasia due to tacrolimus administration in organ transplant recipients have been reported.Here, we report a case of reversible pure red cell aplasia that developed during tacrolimus therapy following living-donor liver transplant. The patient, a 1-year-old girl diagnosed with progressive familial intrahepatic cholestasis type II, underwent living-donor liver transplant when she was 10 months old. She was started on 3 immunosuppressants posttransplant: tacrolimus (0.1 mg/kg/day twice daily), mycophenolate mofetil, and prednisolone (0.2 mg/kg/day). One year after transplant, she developed severe progressive anemia. Her hemoglobin concentration was extremely low (5.4 g/dL). A bone marrow biopsy revealed severe hypoplasia of the erythroblasts with no abnormality of other myelocytes. These findings were suggestive of pure red cell aplasia; we suspected that tacrolimus had caused this based on similar previous cases of tacrolimus-associated pure red cell aplasia. Accordingly, tacrolimus was switched to cyclosporine after this diagnosis. One week after this switch, the patient's red blood cell counts, reticulocytes, and hemoglobin concentration increased. Although tacrolimus is considered to have no significant potential for myelosuppression, cases of tacrolimus-related pure red cell aplasia have occurred. In patients who develop pure red cell aplasia during tacrolimus treatment following living-donor liver transplant, clinicians should consider switching from tacrolimus to another immunosuppressant.

Persistence of constrictive pattern despite improvement in symptoms after the waffle procedure: A case report of constrictive pericarditis.

Constrictive pericarditis (CP) is an uncommon disease characterized by clinical signs of right-sided heart failure subsequent to loss of pericardial compliance. Although pericardiectomy is the accepted treatment for improving cardiac hemodynamics in CP, some patients fail to improve after pericardiectomy. We herein report a case of CP that showed some physical and hemodynamic features with a constrictive pattern that persisted despite the improvement in heart failure symptoms after pericardiectomy. A 61-year-old man was diagnosed with CP 7 months after the onset of symptoms of shortness of breath and edema in the legs. The waffle procedure was performed using an ultrasonic scalpel. Post-operative cardiac catheterization demonstrated a dip-and-plateau pattern in both right ventricular (RV) and left ventricular (LV) pressures, but the RV and LV end-diastolic pressures improved. Moreover, Doppler echocardiography showed an improvement in the change in mitral and tricuspid early velocities with respiration. Decrease in intraoperative right atrial pressure and respiratory variability in LV and RV inflow on echocardiography are important predictors of improvement in post-operative heart failure symptoms. Learning objective: Decrease in intraoperative right atrial pressure and respiratory variability in left ventricular and right ventricular inflow on post-operative echocardiography are important predictors of improvement in heart failure symptoms even if some hemodynamic features characterizing constrictive pericarditis (dip and plateau pattern, Friedreich's sign) persist.>.

Penetration of a swallowed fish bone into pulmonary vein: diagnosis and management.

We present a case of a 71-year-old woman who accidently swallowed a large fish bone that penetrated into the pulmonary vein. She visited the hospital the next day with a complaint of mild chest discomfort with slight pain and fever of 37.4 °C. Contrast-enhanced chest computed tomography (CT) scan revealed a large fish bone with a length of 35 mm impacted in the middle esophagus. The bone had penetrated into the pulmonary vein, causing mediastinitis. Blood tests revealed elevation in the white blood cell count and C-reactive protein level. Because intractable bleeding from pulmonary vein after endoscopic removal can be lethal, endoscopic removal of the fish bone in an operating room under general anesthesia with cardiovascular surgical standby for possible emergency surgery was selected. After endoscopic removal, mediastinal hematoma was absent with a follow-up chest CT scan, and the mediastinitis was treated with intravenous antibiotics. The patient shortly became afebrile with normalized blood test findings. After confirming the normal findings on the follow-up chest CT scan and endoscopic inspection in the next week, she was discharged from the hospital 10 days after hospitalization without any complications. When the swallowed bone penetrates into the major pericardial vessels, unprepared endoscopic removal may result in fatal sequelae such as intractable mediastinal hemorrhage. Urgent consultation with cardiovascular or thoracic surgeons for a possible emergent surgery is needed before endoscopic removal is attempted.

Hyperglycemic hyperosmolar state in an adolescent with type 1 diabetes mellitus.

Hyperglycemic hyperosmolar state (HHS) and diabetic ketoacidosis (DKA) are the most severe acute complications of diabetes mellitus (DM). HHS is characterized by severe hyperglycemia and hyperosmolality without significant ketosis and acidosis. A 14-year-old Japanese boy presented at the emergency room with lethargy, polyuria and polydipsia. He belonged to a baseball club team and habitually drank sugar-rich beverages daily. Three weeks earlier, he suffered from lassitude and developed polyuria and polydipsia 1 week later. He had been drinking more sugar-rich isotonic sports drinks (approximately 1000-1500 mL/day) than usual (approximately 500 mL/day). He presented with HHS (hyperglycemia (1010 mg/dL, HbA1c 12.3%) and mild hyperosmolality (313 mOsm/kg)) without acidosis (pH 7.360), severe ketosis (589 µmol/L) and ketonuria. He presented HHS in type 1 diabetes mellitus (T1DM) with elevated glutamate decarboxylase antibody and islet antigen 2 antibody. Consuming beverages with high sugar concentrations caused hyperglycemia and further exacerbates thirst, resulting in further beverage consumption. Although he recovered from HHS following intensive transfusion and insulin treatment, he was significantly sensitive to insulin therapy. Even the appropriate amount of insulin may result in dramatically decreasing blood sugar levels in patients with T1DM. We should therefore suspect T1DM in patients with HHS but not those with obesity. Moreover, age, clinical history and body type are helpful for identifying T1DM and HHS. Specifically, drinking an excess of beverages rich in sugars represents a risk of HHS in juvenile/adolescent T1DM patients. Learning points: Hyperglycemic hyperosmolar state (HHS) is characterized by severe hyperglycemia and hyperosmolality without significant ketosis and acidosis. The discrimination between HHS of type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) in initial presentation is difficult. Pediatrician should suspect T1DM in patients with HHS but not obesity. Age, clinical history and body type are helpful for identifying T1DM and HHS. Children with T1DM are very sensitive to insulin treatment, and even appropriate amount of insulin may result in dramatically decreasing blood sugar levels.

A case of myelodysplastic syndrome with t(10;18)(q26;q21).

An 82-year-old male was admitted. Pancytopenia, a slightly low white blood cell count (3400/µL), and low levels of red blood cells (2.65 × 106/µL), hemoglobin (10.4 g/dL), and platelets (118,000/µL) were observed. Bone marrow aspiration was performed, revealing hypocellular bone marrow and normal blast levels (0.6%) with no dysplasia. G-banding chromosome analysis revealed the karyotype 45,X,-Y[3]/45, idem, t(10;18)(q26;q21)[13]/46,XY[4]. The patient was diagnosed with myelodysplastic syndrome, unclassified (MDS-U). This is the first case report demonstrating a patient with the chromosomal translocation, t(14;18)(q32;q21), which is extremely rare. This chromosomal aberration was critical for the diagnosis of MDS in this patient.

[Susceptibilities of bacteria isolated from patients with lower respiratory infectious diseases to antibiotics (2005)].

From October 2005 to September 2006, we collected the specimen from 366 patients with lower respiratory tract infections in 12 institutions in Japan, and investigated the susceptibilities of isolated bacteria to various antibacterial agents and patients' characteristics. Of 411 strains that were isolated from specimen (mainly from sputum) and assumed to be bacteria causing in infection, 406 strains were examined. The isolated bacteria were: Staphylococcus aureus 70, Streptococcus pneumoniae 85, Haemophilus influenzae 78, Pseudomonas aeruginosa (non-mucoid) 46, P. aeruginosa (mucoid) 14, Klebsiella pneumoniae 21, and Moraxella subgenus Branhamella catarrhalis 40. Of 70 S. aureus strains, those with 2 microg/ml or less of MIC of oxacillin (methicillin-susceptible S. aureus: MSSA) and those with 4 microg/ml or more of MIC of oxacillin (methicillin-resistant S. aureus: MRSA) were 38 (54.3%) and 32 (45.7%) strains, respectively. Against MSSA, imipenem had the most potent antibacterial activity and inhibited the growth of 37 strains (97.4%) at 0.063 microg/ml or less. Against MRSA, arbekacin and vancomycin showed the most potent activity and inhibited the growth of all the strains at 1 microg/ml. Carbapenems showed the most potent activities against S. pneumoniae and in particular, panipenem inhibited the growth of all the strains at 0.063 microg/ml or less. Faropenem also had a preferable activity and inhibited the growth of all the strains at 0.25 microg/ml. In contrast, there were high-resistant strains (MIC: over 128 microg/ml) for erythromycin (38.1%) and clindamycin (22.6%). Against H. influenzae, levofloxacin showed the most potent activity and its MIC90 was 0.063 microg/ml or less. Meropenem showed the most potent activity against P. aeruginosa (mucoid) and its MIC90 was 0.5 microg/ml. Against P. aeruginosa (non-mucoid), arbekacin had the most potent activity and its MIC90 was 8 microg/ml. Against K. pneumoniae, cefozopran was the most potent activity and inhibited the growth of all the strains at 0.063 microg/ml or less. Also, all the antibacterial agents except ampicillin generally showed a potent activity against M. (B.) catarrhalis and the MIC90 of them were 2 microg/ml or less. The approximately half the number (53.6%) of the patients with respiratory infection were aged 70 years or older. Bacterial pneumonia and chronic bronchitis accounted for 44.3% and 29.8% of all the respiratory infection, respectively. The bacteria frequently isolated from the patients with bacterial pneumonia were S. aureus (15.4%), S. pneumoniae (23.4%), and H. influenzae (21.3%). S. aureus (25.4%) and S. pneumoniae (18.0%) also were frequently isolated from the patients with chronic bronchitis. Before the drug administration, the bacteria frequently isolated from the patients were S. pneumoniae (22.0%) and H. influenzae (21.4%). The bacteria frequently isolated from the patients treated with macrolides were S. pneumoniae and P. aeruginosa, and their isolation frequencies were each 35.3%.

[Mitral valve myxoma that was resected with valve plasty].

Cardiac myxomas arising from the mitral valve are extremely rare. We describe the case of an asymptomatic 47-year-old male patient with a myxoma measuring 11 mm in diameter originating from the anterior leaflet of the mitral valve as observed by transthoracic echocardiography. The tumor was excised, and a defect in the anterior leaflet of the mitral valve was patched with autologous pericardium. Mitral valve regurgitation was observed and partial annuloplasty was performed. Following this, mitral valve regurgitation was observed to be diminished.

CT-Guided Intranodal Lymphangiography for Postoperative Chylous Ascites.

The utility and minimal invasiveness of ultrasound-guided intranodal lymphangiography have already been reported by several researchers. Although ultrasound-guided intranodal lymphangiography is known to be not technically difficult in general, a patient's edematous groin due to hypoalbuminemia resulting from chylous ascites made it too challenging to detect and prick the lymph nodes precisely. This report describes a 71-year-old female with refractory chylous ascites due to an operation for an extrahepatic bile duct cancer, who was successfully treated by computed tomography (CT)-guided intranodal lymphangiography. After switching from ultrasound- to CT-guided lymphangiography, the procedure was successfully performed, and the refractory chylous ascites was treated.

Aortic valve replacement in an elderly patient with factor XI deficiency.

Factor XI (FXI) deficiency is rare and associated with bleeding after surgical procedures. We report a case of an 80-year-old woman with severe aortic valve stenosis. FXI deficiency was diagnosed due to prolonged activated partial thromboplastin time. Aortic valve replacement was performed using a porcine bioprosthetic valve. Intra-operation bleeding was controlled by the transfusion of a fresh frozen plasma. The postoperative course was uneventful.

A patient with obstructive jaundice due to bleeding in the common bile duct after ultrasound-guided liver biopsy.

A-63-year-old man was referred to our hospital for interferon therapy to treat chronic hepatitis C. The patient complained of right upper abdominal pain 1 hour after the ultrasound-guided liver biopsy. Bleeding in the gallbladder and the common bile duct were found on emergency CT. Obstructive jaundice due to the common bile duct hematoma was diagnosed, and endoscopic retrograde cholangiopancreatography(ERCP) was performed, and a filling defect thought to be a hematoma was seen in the bile duct on cholangiography. The hematoma in the bile duct was extracted after endoscopic sphincteroyomy.

Heparin accelerates pulmonary artery development in neonate rabbits.

Pulmonary vascular resistance drops sharply within a few minutes after birth for the survival of neonates. A majority of this resistance is caused by "pulmonary vascular bed" or vessel lacking smooth muscle cells. Heparin is known to promote proliferation and development of endothelial cells and to subsequently decrease their overall vascular resistance, but its detailed features remained unknown. Therefore, in this study we treated neonatal rabbits with heparin, protamine (antagonist of heparin), or saline, and evaluated histopathological features of vascular endothelial cells using two different types of computer assisted image analysis, i.e., CAS200 and NIH image. These two systems detected the percentage of vascular endothelial area per fields (VA) and CD31-positive area per total area of tissue following subtraction of background stain. CD31 was used as an endothelial cell marker. Heparin treated rabbits were associated with significant decrement of pulmonary/systemic artery pressure (Pp/Ps) (21.0 +/- 6.0%) compared to protamine (29.9 +/- 6.1%) or saline (29.4 +/- 3.0%) treated animals. The values of VA obtained by the two image analyses (CAS200 and NIH image) were significantly increased in heparin treated animals (38.4 +/- 3.2% determined by CAS200 and 24.0 +/- 1.3% by NIH image) compared to protamine (30.2 +/- 3.9% and 19.2 +/- 1.8%) or saline (33.2 +/- 1.5% and 20.8 +/- 3.8%) treated animals on 14th day of treatment. The present study indicates that heparin accelerates pulmonary vascular bed development probably by increasing the number and volume of endothelial cells, which subsequently contributes to the decrease in pulmonary vascular resistance.