Chronological transitions of hepatocyte growth factor treatment effects in spinal cord injury tissue

Inflammatory responses are known to suppress neural regeneration in patients receiving stem cell-based regenerative therapy for spinal cord injury (SCI). Consequently, pathways involved in neurogenesis and immunomodulation, such as the hepatocyte growth factor (HGF)/MET signaling cascade, have garnered significant attention. Notably, various studies, including our own, have highlighted the enhanced recovery of locomotor functions achieved in SCI animal models by combining HGF pretreatment and human induced stem cell-derived neural stem/progenitor cell (hiPSC-NS/PC) transplantation. However, these studies implicitly hypothesized that the functionality of HGF in SCI would be time consistent and did not elucidate its dynamics. In the present article, we investigated the time-course of the effect of HGF on SCI, aiming to uncover a more precise mechanism for HGF administration, which is indispensable for developing crystallizing protocols for combination therapy. To this end, we performed a detailed investigation of the temporal variation of HGF using the RNA-seq data we obtained in our most recent study. Leveraging the time-series design of the data, which we did not fully exploit previously, we identified three components in the effects of HGF that operate at different times: early effects, continuous effects, and delayed effects. Our findings suggested a concept where the three components together contribute to the acceleration of neurogenesis and immunomodulation, which reinforce the legitimacy of empirically fine-tuned protocols for HGF administration and advocate the novel possibility that the time-inconsistent effects of HGF progressively augment the efficacy of combined therapy.

Human-induced pluripotent stem cell-derived neural stem/progenitor cell ex vivo gene therapy with synaptic organizer CPTX for spinal cord injury

The transplantation of neural stem/progenitor cells (NS/PCs) derived from human induced pluripotent stem cells (hiPSCs) has shown promise in spinal cord injury (SCI) model animals. Establishing a functional synaptic connection between the transplanted and host neurons is crucial for motor function recovery. To boost therapeutic outcomes, we developed an ex vivo gene therapy aimed at promoting synapse formation by expressing the synthetic excitatory synapse organizer CPTX in hiPSC-NS/PCs. Using an immunocompromised transgenic rat model of SCI, we evaluated the effects of transplanting CPTX-expressing hiPSC-NS/PCs using histological and functional analyses. Our findings revealed a significant increase in excitatory synapse formation at the transplantation site. Retrograde monosynaptic tracing indicated extensive integration of transplanted neurons into the surrounding neuronal tracts facilitated by CPTX. Consequently, locomotion and spinal cord conduction significantly improved. Thus, ex vivo gene therapy targeting synapse formation holds promise for future clinical applications and offers potential benefits to individuals with SCI.

Hepatocyte growth factor pretreatment boosts functional recovery after spinal cord injury through human iPSC-derived neural stem/progenitor cell transplantation

BACKGROUND

Human induced pluripotent stem cell-derived neural stem/progenitor cell (hiPSC-NS/PC)-based cell transplantation has emerged as a groundbreaking method for replacing damaged neural cells and stimulating functional recovery, but its efficacy is strongly influenced by the state of the injured spinal microenvironment. This study evaluates the impact of a dual therapeutic intervention utilizing hepatocyte growth factor (HGF) and hiPSC-NS/PC transplantation on motor function restoration following spinal cord injury (SCI).

METHODS

Severe contusive SCI was induced in immunocompromised rats, followed by continuous administration of recombinant human HGF protein into the subarachnoid space immediately after SCI for two weeks. Acute-phase histological and RNA sequencing analyses were conducted. Nine days after the injury, hiPSC-NS/PCs were transplanted into the lesion epicenter of the injured spinal cord, and the functional and histological outcomes were determined.

RESULTS

The acute-phase HGF-treated group exhibited vascularization, diverse anti-inflammatory effects, and activation of endogenous neural stem cells after SCI, which collectively contributed to tissue preservation. Following cell transplantation into a favorable environment, the transplanted NS/PCs survived well, facilitating remyelination and neuronal regeneration in host tissues. These comprehensive effects led to substantial enhancements in motor function in the dual-therapy group compared to the single-treatment groups.

CONCLUSIONS

We demonstrate that the combined therapeutic approach of HGF preconditioning and hiPSC-NS/PC transplantation enhances locomotor functional recovery post-SCI, highlighting a highly promising therapeutic strategy for acute to subacute SCI.

Microenvironmental modulation in tandem with human stem cell transplantation enhances functional recovery after chronic complete spinal cord injury

While rapid advancements in regenerative medicine strategies for spinal cord injury (SCI) have been made, most research in this field has focused on the early stages of incomplete injury. However, the majority of patients experience chronic severe injury; therefore, treatments for these situations are fundamentally important. Here, we hypothesized that environmental modulation via a clinically relevant hepatocyte growth factor (HGF)-releasing scaffold and human iPS cell-derived neural stem/progenitor cells (hNS/PCs) transplantation contributes to functional recovery after chronic complete transection SCI. Effective release of HGF from a collagen scaffold induced progressive axonal elongation and increased grafted cell viability by activating microglia/macrophages and meningeal cells, inhibiting inflammation, reducing scar formation, and enhancing vascularization. Furthermore, hNS/PCs transplantation enhanced endogenous neuronal regrowth, the extension of graft axons, and the formation of circuits around the lesion and lumbar enlargement between host and graft neurons, resulting in the restoration of locomotor and urinary function. This study presents an effective therapeutic strategy for severe chronic SCI and provides evidence for the feasibility of regenerative medicine strategies using clinically relevant materials.

Concurrent dorsal subpial schwannoma and ventral meningioma arising at the same upper cervical level: a case report

INTRODUCTION

Multiple spinal cord tumors rarely occur without genetic predisposition, and concurrent tumors with discrete pathologies developed at the same spinal level are most rare. Here, we report a case of concurrent dorsal schwannoma and ventral meningioma arising at the same upper cervical level (C1-C2).

CASE PRESENTATION

A 55-year-old woman presented with neck pain and upper and lower extremity numbness for 1 year. Magnetic resonance imaging of the cervical spine showed a partially circumferential C-shaped intradural extramedullary tumor at C1-C2. The preoperative diagnosis based on imaging was intradural extramedullary meningioma with circumferential development. Surgical resection was performed, and dorsal subpial and ventral tumors were detected. Intraoperative pathological diagnosis was schwannoma for the dorsal tumor and meningioma for the ventral tumor. Both tumors were completely resected, followed by circumferential durotomy and duroplasty (Simpson grade 1 resection). Although symptoms related to cerebrospinal fluid hypovolemia occurred immediately after surgery, they disappeared within several days. At 2 years postoperatively, no local recurrence has been identified with mild kyphotic cervical malalignment.

DISCUSSIONS

Only nine cases of concurrent multiple spinal tumors with discrete histopathological types at the same cervical level have been reported to date, however, this is the first case of meningioma combined with subpial schwannoma. Furthermore, although the ventral location of meningioma often compelled inadequate resection leaving behind a dura mater from which meningioma originated, a gross total resection including dura mater was achieved accompanied with circumferential duroplasty. Careful and sequential postoperative follow-up is ongoing for this individual.

P4731Procedure-related acute thrombosis after surgical left atrial appendage occlusion for atrial fibrillation

Background/Introduction

Left atrial appendage (LAA) occlusion is an effective strategy for thromboembolism prevention in patients with atrial fibrillation (AF), and the novel methods of occlusion is various. The acute thrombosis after percutaneous LAA occlusion devices has been recently reported, but thrombus formation after surgical LAA occlusion is still unclear.

Purpose

This study aimed to analyse the incidence and prognosis of thrombus formation on closure stump line in patients with AF who underwent surgical LAA occlusion.

Methods

This study retrospectively analised the data from patients treated with two methods of surgical LAA closure, resection or clipping, from January 2014 to November 2018.

Results

A total of 187 consecutive patients with AF underwent surgical LAA closure (31 clipping and 156 stapler resection). 170 patients (91%) underwent cardiac CT for LAA imaging on postoperative day 2. The incidence of acute procedure-related thrombus formation in full cohort was 19% (35 cases). The incidence of acute thrombus in patients with clipping and resection was 19% and 16%, respectively (Fisher's exact test, p=0.8). All of 35 patients who had thrombus on LAA closure stump line underwent cardiac CT again 3 months after the primary CT. In all patients with secondary cardiac CT, thrombus on LAA closure stump line disappeared. No symptomatic thromboembolism occurred during the follow-up from operation to secondary CT scan.

Conclusion(s)

Thrombus formation on stump after surgical LAA closure may often occur on acute phase. The optimal LAA imaging and anti-coagulation therapy after surgical LAA occlusion will prevent patients with acute thrombus from thromboembolism.

[A new technique of aortic occlusion in patient with severe aortic calcification]

A 63-year-old woman with severe aortic valve insufficiency and bilateral subclavian artery occlusion underwent ascending aorta-to-biaxillary artery bypass and aortic valve replacement, simultaneously. Because of severe aortic calcification, a hand-made aortic occluder was utilized to prevent embolic stroke. We believe that the new technique of aortic occllusion might be very useful for patients with severe aortic calcification.

Chromospheric alfvenic waves strong enough to power the solar wind

Alfvén waves have been invoked as a possible mechanism for the heating of the Sun's outer atmosphere, or corona, to millions of degrees and for the acceleration of the solar wind to hundreds of kilometers per second. However, Alfvén waves of sufficient strength have not been unambiguously observed in the solar atmosphere. We used images of high temporal and spatial resolution obtained with the Solar Optical Telescope onboard the Japanese Hinode satellite to reveal that the chromosphere, the region sandwiched between the solar surface and the corona, is permeated by Alfvén waves with strong amplitudes on the order of 10 to 25 kilometers per second and periods of 100 to 500 seconds. Estimates of the energy flux carried by these waves and comparisons with advanced radiative magnetohydrodynamic simulations indicate that such Alfvén waves are energetic enough to accelerate the solar wind and possibly to heat the quiet corona.

Small-scale jetlike features in penumbral chromospheres

We observed fine-scale jetlike features, referred to as penumbral microjets, in chromospheres of sunspot penumbrae. The microjets were identified in image sequences of a sunspot taken through a Ca II H-line filter on the Solar Optical Telescope on board the Japanese solar physics satellite Hinode. The microjets' small width of 400 kilometers and short duration of less than 1 minute make them difficult to identify in existing observations. The microjets are possibly caused by magnetic reconnection in the complex magnetic configuration in penumbrae and have the potential to heat the corona above a sunspot.

[Semi-automatic suturing device for minimally invasive cardiac surgery]

Semi-automatic suturing device for minimally invasive cardiac surgery (MICS) was developed. Exchange of the needle is attained by an automatic grasping action and the needle shift parallel to the long axis of the device. This device (5 mm in diameter) can be inserted through a 5 mm trocar. This new device facilitates not only operative procedure such as mitral valve replacement and patch closure during MICS but conventional cardiac surgery.

Video-assisted cardioscopy for infectious endocarditis

We successfully resected vegetation of infectious endocarditis in right ventricular outflow tract using a video-assisted cardioscopy without ventriculotomy. Video-assisted cardioscopy provided clear and precise visualization of vegetation on the anterior wall of right ventricular outflow. This technique is effective to visualize remote intra-cardiac structures, and to facilitate repairs, while avoiding the need for extended cardiac incisions.

Conventional coronary artery bypass grafting in patients with total occlusion of the internal carotid artery

The number of patients with coexisting disease of the coronary and carotid arteries is increasing. Patients with total occlusion of the carotid artery may have a higher risk of stroke during cardiopulmonary bypass surgery and in the perioperative period. We report our results for coronary artery bypass grafting (CABG) in patients with total occlusion of the carotid artery. We examined 269 patients who underwent carotid artery duplex scanning (CADS) before CABG between November 1995 and January 1998. Among them, 11 patients (4.1%) had total occlusion of a carotid artery. Four patients underwent elective CABG and five underwent emergency CABG. One patient underwent anastomosis of the superficial temporal artery to the middle cerebral artery (STMC) and one patient underwent a combined CABG and carotid endoarterectomy (CEA) procedure. A transient neurological event occurred in only one patient (9.1%). The other patients recovered uneventfully. Our results suggest that CABG can be performed without stroke in patients with total unilateral occlusion of a carotid artery using our strategies.

Intraoperative echocardiographic imaging of coronary arteries and graft anastomoses during coronary artery bypass grafting without cardiopulmonary bypass

BACKGROUND

No accepted approach exists for the intraoperative evaluation of the quality of coronary arteries and the technical adequacy of graft anastomoses during coronary artery bypass grafting without cardiopulmonary bypass.

METHODS AND RESULTS

We assessed the accuracy of high-frequency epicardial echocardiography and power Doppler imaging in evaluating coronary arteries during coronary artery bypass grafting without cardiopulmonary bypass. To validate measurements of coronary arteries and graft anastomoses by high-frequency epicardial echocardiography and power Doppler imaging, we compared luminal diameters determined by these methods with diameters determined histologically in a study of off-pump coronary artery bypass grafting in 20 dogs. Technical errors were deliberately created in 10 grafts (stenosis group). The results of these animal validation studies showed that the maximum luminal diameters of coronary arteries and graft anastomoses measured by high-frequency epicardial echocardiography (HEE) and power Doppler imaging (PDI) correlated well with the histologic measurements: HEE = 1.027 x Histologic measurements + 0.005 (P <.0001); PDI = 0.886 x Histologic measurements + 0.0453 (P =.0001). Similar results were found in the evaluation of the stenosis group: PDI = 0.991 x Histologic measurements + 0.074 (P <.0001). Subsequently, we demonstrated the clinical applicability of this approach in 12 patients who underwent minimally invasive or off-pump coronary artery bypass grafting. Twenty graft anastomoses were examined intraoperatively by high-frequency epicardial echocardiography and power Doppler imaging, and luminal diameters determined by power Doppler imaging were compared with those determined by postoperative coronary angiography. The results demonstrated that graft anastomosis by power Doppler imaging correlated well with the angiographic measurements: PDI = 1.018 x Angiographic measurements - 0.106 (P <.0001).

CONCLUSION

High-frequency epicardial echocardiography can provide meaningful information on the target coronary artery, and power Doppler imaging can accurately measure graft anastomoses and can detect technical errors and inadequacies during coronary artery bypass grafting without cardiopulmonary bypass.

Elevated sympathetic nervous activity in mice deficient in alphaCGRP

alpha-Calcitonin gene-related peptide (alphaCGRP) is a pleiotropic neuropeptide implicated in a variety of physiological processes. To better understand the biological functions of alphaCGRP, we developed an alphaCGRP-null mouse model using a gene targeting approach. Recordings of mean arterial pressure (MAP) and heart rate (HR) showed that basal MAP and HR were significantly higher in both anesthetized and conscious, unrestrained alphaCGRP-null mice than in corresponding wild-type mice. The elevated MAP in alphaCGRP-null mice was shown to be the result of elevated peripheral vascular resistance by alpha-adrenergic blockade with prazosin and by transthoracic echocardiogram, which revealed no significant differences between alphaCGRP-null and wild-type mice in the stroke volume, fractional shortening, and ejection fraction. Moreover, evaluation of autonomic nervous activity by measuring HR after pretreatment of atropine and/or atenolol and by analyzing arterial baroreceptor reflexes showed sympathetic nervous activity to be significantly elevated in alphaCGRP-null mice; elevated levels of urinary catecholamine metabolites and decreased HR variability in mutant mice were also consistent with that finding. These findings suggest that alphaCGRP contributes to the regulation of cardiovascular function through inhibitory modulation of sympathetic nervous activity.

Predictive risk factors for delayed extubation in patients undergoing coronary artery bypass grafting

Prolonged mechanical ventilation increases hospitalization costs, airway and lung trauma, and stress. The objective of this study was to elucidate patient characteristics and operative variables that predict delayed extubation in patients undergoing coronary artery bypass grafting (CABG). The records of 167 patients who underwent CABG between 1994 and 1998 were examined retrospectively. The patients were divided into early and delayed extubation groups. Putative factors affecting the duration of intubation were included in a univariate analysis using the t-test and chi-squared test. A logistic regression model was then developed to determine the factors associated with delayed extubation. Forty-four percent of the patients needed prolonged mechanical ventilation (more than 24h). Univariate predictors of delayed extubation (P < 0.05) were emergency surgery, preoperative use of an intra-aortic balloon pump (IABP), the duration of anesthesia, surgery, cardiopulmonary bypass and aortic cross-clamping, the total volume of fentanyl. lowest rectal temperature, glucose level, perioperative transfusion, bleeding, perioperative heart failure, perioperative insertion of IABP, postoperative transfusion, cardiac index, inspired oxygen fraction (FiO2), arterial oxygen tension (PaO2), the PaO2/FiO2 ratio, and the volume of catecholamine. In the delayed extubation group, the intensive care unit stay was significantly longer (P < 0.001) and re-exploration was required more frequently (P = 0.004). Excellent prediction was provided by a model consisting of six variables: age, duration of surgery, perioperative heart failure, glucose level, postoperative transfusion, and the PaO2/FiO2 ratio. These results suggest that decreasing the cardiopulmonary bypass time, maintaining a low glucose level during cardiopulmonary bypass, and ensuring adequate perioperative hemostasis may help to avoid pulmonary dysfunction and delayed extubation. Moreover, the PaO2/FiO2 ratio may be a useful predictor of delayed extubation in patients undergoing CABG.

L-Arginine given after ischaemic preconditioning can enhance cardioprotection in isolated rat hearts

OBJECTIVE

Ischaemic or pharmacological preconditioning with L-arginine has been reported to be insufficient for optimal cardioprotection. The ability of nitric oxide (NO) to enhance ischaemic preconditioning was assessed, and the role of L-arginine-induced ischaemic preconditioning in myocardial protection was determined.

METHODS

Isolated rat hearts were prepared and divided into six groups: control hearts (control, n=6) were perfused without global ischaemia at 37 degrees C for 160 min; global ischaemia hearts (GI, n=6) were subjected to ischaemia for 20 min and reperfusion for 120 min; ischaemic preconditioned hearts (IP, n=6) received 2 min of zero-flow global ischaemia followed by 5 min reperfusion, before 20 min of global ischaemia; L-arginine hearts (ARG, n=6) received 1 mmol/l L-arginine for 5 min, before 20 min of global ischaemia; ischaemic preconditioning plus nitro-L-arginine methyl ester hearts (IP+L-NAME, n=6) received 2 min of ischaemic preconditioning and 5 min reperfusion with 3 mmol/l L-NAME in Krebs-Henseleit buffer, before 20 min of global ischaemia; and ischaemic preconditioning plus L-arginine hearts (IP+ARG, n=6) received 2 min of ischaemic preconditioning and 5 min reperfusion with 1 mmol/l L-arginine in Krebs-Henseleit buffer. Haemodynamic parameters and coronary flow were recorded continuously. Nitrites and nitrates (NOx) were measured 5 and 60 min after reperfusion, and infarct size was also determined.

RESULTS

In the IP+ARG group, significant amelioration and preservation of left ventricular peak developed pressure and coronary flow was observed compared with the GI, IP, ARG and IP+L-NAME groups. Infarct size in the IP+ARG group was reduced significantly compared with that in the GI, IP, ARG and IP+L-NAME groups. Significant preservation of NOx was observed during reperfusion in the IP+ARG group compared with the GI group.

CONCLUSIONS

Inhibition of NO synthase with L-NAME had little impact on ischaemic preconditioning, suggesting that endogenous NO is not a major mediator of ischaemic preconditioning. Nevertheless, enhancement of the effects of ischaemic preconditioning can be achieved with L-arginine, a precursor of NO, improving post-ischaemic functional recovery and infarct size in the isolated rat heart.

Right heart bypass for left circumflex coronary artery bypass grafting

Displacement of the heart to expose the left circumflex artery (LCX) causes hemodynamic disturbance during off-pump coronary artery bypass grafting (CABG). We applied right heart bypass (RHB) using a heparin-coated centrifugal pump without an oxygenator in an attempt to stabilize the hemodynamics. Five mongrel dogs (15.5-20 kg) were used. Hemodynamic parameters were continuously monitored at a fixed rate of 80 beats/min. The LCX was exposed with the use of an Octopus Tissue Stabilizer. After baseline data were obtained, each dog was placed in the Trendelenburg position. Finally, RHB was established with different pump flows. LCX exposure caused a significant decrease in aortic flow (to 33.1% +/- 13.1% of the baseline value) and arterial mean pressure (to 68.3% +/- 8.5%) (P < 0.001). Trendelenburg positioning caused these values to recover to 57.1% +/- 6.7% and 72.5% +/- 7.7%, respectively. RHB with 50% flow significantly improved the hemodynamic values, although 100% flow significantly increased LAP by 134.8% +/- 19.7% (P < 0.01). Tilting of the canine heart to expose the LCX caused significant deterioration of the hemodynamic values. Trendelenburg positioning was moderately effective, and RHB very effective, in improving the hemodynamics. In a limited number of cases, an appropriate flow of RHB may provide safe hemodynamic assistance during off-pump CABG of the LCX.

[A case of Down syndrome with ventricular septal defect and hemodynamical Eisenmenger syndrome]

A 10 month-old infant with Down syndrome having ventricular septal defect and pulmonary hypertension performed cardiac catheterization, which resulted in a slight increase in the pulmonary vascular resistance from 10.8 to 11.3 unit.m2. Lung biopsy findings showed at most an early grade 2 Heath-Edwards classification, and an index of pulmonary vascular disease of 1.1, both of which indicated operability for total correction. He underwent surgical correction and the pulmonary arterial pressure significantly decrease. Although he suffered chylothorax in 5th postoperative day, he did not developed pulmonary hypertension crisis.

Transxiphoid approach for intracardiac repair using video-assisted cardioscopy

Video-assisted cardioscopy (VAC) is a novel tool for providing clear visualization of small intracardiac structures and achieving complete repair in minimally invasive surgery. Between July 1999 and July 2000, 12 patients with atrial septal defect and ventricular septal defect underwent surgical repair using a combined procedure with the transxiphoid approach and VAC in our institution. The mean skin incision was 5.4 cm, and the postoperative courses of all the patients were uneventful without any complications. The mean hospital stay was 8.3 days and 1 patient (8.3%) needed blood products. Our experience showed the technical feasibility and acceptable surgical results of transxiphoid approach using a VAC.

Strategies for CABG patients with carotid artery disease and perioperative neurological complications

Postoperative neurological complications not only increase morbidity and mortality, but also prolong hospital stay and elevate hospital costs. From 1995, carotid artery duplex scanning (CADS) has been performed in our hospital as screening for cerebrovascular disease in patients undergoing nonemergency coronary artery bypass grafting (CABG). This study was designed to evaluate the usefulness of our strategy for preventing stroke during CABG. Between 1995 and 1997, 179 patients underwent isolated CABG. Of the nonemergency CABG patients, 146 underwent preoperative CADS. Three patients underwent a combined carotid endoarterectomy (CEA)/CABG procedure. One hundred and thirteen patients were men (77.3%), and the median age was 64, with a range of 39-82 years. The mean graft number was 2.7 +/- 0.9. Previous neurological events had occurred in 12 patients. Forty-five patients (30.8%) had abnormal CADS findings. Two (1.4%) of these patients had carotid stenosis > or = 90% in area, and five had total occlusion of the carotid artery. When the risk factors were evaluated, age and previous cerebrovascular disease (CVD) were found to be significantly higher in the group with abnormal CADS findings (P = 0.0012 and P = 0.0312). On multivariate analysis, the predictor of abnormal CADS findings were age and previous CVD (P < 0.01 and P < 0.05). Six patients (3.3%) developed postoperative stroke due to emboli (five cases) or perioperative hypoperfusion (one case). Three patients who underwent the combined CEA/CABG procedure did not suffer from any neurological complications. Preoperative screening by CADS is helpful for evaluating the presence of carotid artery disease in patients undergoing CABG. Further investigations to clarify the carotid hemodynamics are important, and synthetic assessment will be required to determine the most appropriate operative strategy.

Predictive risk factors for pulmonary oxygen transfer in patients undergoing coronary artery bypass grafting

The ratio of arterial oxygen tension to inspired oxygen fraction (PaO2/FiO2) is a useful indicator for weaning patients from mechanical ventilation and a reliable predictor of pulmonary dysfunction after cardiac surgery. The aim of this study was to elucidate the patient characteristics and variables that affect the PaO2/FiO2 ratio. Between 1994-1998, 167 patients who underwent coronary artery bypass grafting (CABG) were examined retrospectively. Spearman's correlation coefficients were calculated between the PaO2/FiO2 ratio and intubation period, and length of ICU stay. Patients were then divided into two groups with a PaO2/FiO2 ratio < 350 and PaO2/FiO2 ratio > or = 350. Univariate analysis of the putative risk factors was performed. A logistic regression model was developed to evaluate factors that would influence the PaO2/FiO2 ratio. A significant correlation was observed between the PaO2/FiO2 ratio and intubation period, and length of ICU stay. Univariate predictors of a PaO2/FiO2 ratio < 350 were low body weight, low preoperative PaO2 long operation time, high FiO2, low postoperative PaO2 history of smoking, hypertension and opening of pleura (p < 0.05). Excellent prediction was found with a model consisting of preoperative PaO2 and hypertension.

CONCLUSION

The results of this study suggest that patients with a low preoperative PaO2 or hypertension may need more careful peri- and postoperative management since these factors are closely associated with the PaO2/FiO2 ratio.

Allogenicity of cryopreserved human fibroblasts: cryopreservation does not downregulate the allogenicity of fibroblasts making up the matrices of allografts

BACKGROUND

Although cryopreserved tissue allografts are being widely used, long-term degeneration of implanted cryopreserved allografts has become a problem. Although immunologic rejection has been suggested to play a part in this degeneration, cryopreserved allografts are considered to be less immunogenic than fresh allografts.

OBJECTIVE

We investigated the effect of cryopreservation on the allogenicity of the fibroblasts that make up the matrices of allografts.

METHODS

Fibroblast cell strains obtained from surgically resected lung specimens were used. Allogenicity-related antigens expressed on the cell surface (human leukocyte antigen 1, human leukocyte antigen 2, and intercellular adhesion molecule 1), stimulation indices during 1-way mixed lymphocyte-fibroblast cell culture, and proliferation indices of freshly passaged fibroblasts and cryopreserved fibroblasts stored for 1, 4, and 24 weeks were examined. Flow cytometric analysis with monoclonal antibodies was used to test for cell surface antigens, and a colorimetric methyl-thiazol-diphenyl-tetrazolium assay was used to assess stimulation indices and fibroblast proliferation indices. The effect of exogenous interferon-gamma on the degree of expression of human leukocyte antigen 1, human leukocyte antigen 2, and intercellular adhesion molecule 1 was examined simultaneously.

RESULTS

The proliferation indices of fibroblasts were well maintained by cryopreservation. Expression of human leukocyte antigen 1, human leukocyte antigen 2, and intercellular adhesion molecule 1 by fibroblasts was significantly upregulated by interferon-gamma, and cryopreservation did not downregulate this expression.

CONCLUSION

Our study suggests that although the fibroblast cell component may be beneficial in restoring allograft function properties initially, it may render the implanted allograft more immunogenic, ultimately resulting in greater rejection and inflammatory responses by the host and, in turn, degeneration of the graft.

Right heart mini-pump bypass for coronary artery bypass grafting: experimental study

BACKGROUND

Visualization of the left circumflex arteries during off-pump coronary artery bypass grafting (CABG) causes hemodynamic disturbance. We investigated whether right heart mini-pump bypass (RHB), using a centrifugal pump, improved the safety of this procedure by studying the influences of different heart displacement positions, the Trendelenburg maneuver and RHB on hemodynamics.

METHOD

Hemodynamic parameters in eight mongrel dogs (15.5-20 kg) were continuously monitored at a fixed heart rate of 80 beats/min through a conventional median sternotomy. The posterior descending artery (PDA) and left circumflex artery (LCX) were exposed using an Octopus tissue stabilizer. After evaluating the influence of the Trendelenburg maneuver on hemodynamics, a heparin-coated centrifugal pump without an oxygenator was introduced and the impact of different pump flow volumes was investigated during RHB.

RESULTS

LCX exposure caused significant decreases in aortic flow (to 35. 1+/-12.8%) and arterial mean pressure (to 66.1+/-9.3%) compared with baseline (P<0.001). In contrast to PDA exposure, values remained significantly decreased during the Trendelenburg maneuver. On the contrary, RHB significantly improved the hemodynamic impairments caused by both heart displacement procedures, especially LCX exposure, although 100% pump flow significantly increased left atrial pressure to 131.3+/-19.5% (P<0.01).

CONCLUSION

Exposure of the LCX caused severe hemodynamic deterioration, which was not fully reversed by the Trendelenburg maneuver. In contrast, RHB significantly improved hemodynamics, and therefore this technique can be beneficial for CABG of LCX in the limited cases.

[Recent donation and clinical results of homograft tissue]

Between August 1995 and July 1999, we have experienced 14 donors for allografts (mean age: 39.8 +/- 15.8, M/F = 10/4, mean warm ischemic time: 359 minutes). Donated tissues were included 12 aortic valves and 12 pulmonary valves, respectively. Since February 1994, clinical diagnoses of 14 patients included 7 congenital heart disease, 5 infective heart disease, 1 artificial graft infection, and 1 thrombosed valve. There was no graft-transmitted disease. In congenital heart disease, 3 patients (HLHS: 1, Truncus: 1, TOF + PA: 1) died (early mortality, 42%) and 1 with TGA had residual conduit stenosis. However, in infective heart disease, all patients survived without recurrent infection and did not need reoperation (early mortality, 0%). Our clinical results of homograft implantation for infective heart disease were excellent, but more careful consideration will be needed for congenital heart disease in neonates and/or patients with poor preoperative condition.

Coronary artery bypass grafting in a patient with human immunodeficiency virus: role of perioperative active anti-retroviral therapy

In a patient with severe ischemic heart disease and advanced human immunodeficiency virus (HIV) infection, vigorous perioperative treatment with anti-retroviral agents was given and coronary artery bypass surgery using cardiopulmonary bypass was successfully performed. This strategy could become the standard for patients with cardiovascular disease and advanced HIV infection. The following aspects of this case require further investigation: (1) lack of a reactive increase in the neutrophil count, (2) transient extreme reduction of lymphocytes, and (3) a relative decrease in the CD8+ cell ratio.

Effect of 1,25-dihydroxyvitamin D3 on induction of scavenger receptor and differentiation of 12-O-tetradecanoylphorbol-13-acetate-treated THP-1 human monocyte like cells

We investigated the effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on the expression of scavenger receptors in human monocytic cell line (THP-1 cells) treated for 24 h with 12-O-tetradecanoylphorbol-13-acetate (TPA) which induces their differentiation into macrophages. The capacity to degrade 125I-labeled acetyl low density lipoprotein (LDL) was developed in accordance with macrophage differentiation. The treatment with 10 nM 1,25(OH)2D3 for 72 h inhibited the degradation of acetyl LDL by THP-1 macrophages in a dose-dependent manner, suggesting that 1,25(OH)2D3 inhibits scavenging function in macrophages. In order to clarify the mechanism of its inhibitory effect on degradation of acetyl LDL, we performed the ligand binding assay using 125I-labeled acetyl LDL. Scatchard analysis revealed that 1,25(OH)2D3 decreased the number of scavenger receptors without changing the affinity for acetyl LDL. We next examined the effect of 1,25(OH)2D3 on the expression of scavenger receptor mRNA. The mRNA of type I scavenger receptor was first detected in THP-1 cells 4 days after the treatment with TPA, the mRNA level increased up to 6 days, and then decreased. The treatment with 1,25(OH)2D3 for 72 h dramatically decreased the mRNA levels after the acquisition of macrophage phenotypes as evidenced by nonspecific esterase staining. However, 1,25(OH)2D3 did not affect the activity of nonspecific esterase nor the induction of interleukin-1 beta mRNA by lipopolysaccharide in THP-1 macrophages. These findings suggest that 1,25(OH)2D3 exclusively decreases the expression of scavenger receptors in TPA-induced THP-1 macrophages without affecting the basic cellular functions as macrophages.

[A case of dextrocardia concomitant with tetralogy of Fallot, patent ductus arteriosus and bronchiectasia]

We report a case of dextrocardia concomitant with tetralogy of Fallot (TOF), patent ductus arteriosus (PDA), bronchiectasia, and pulmonary tuberculosis. A 24-years-old man without surgical operation for TOF, whose diagnosis had been made at infancy, was admitted to the Osaka City University Hospital because of massive hemoptysis. The diagnosis of pulmonary tuberculosis was made. He received anti-tuberculotic drugs and bronchial arterial embolization improved his symptoms. A case of mirror-image dextrocardia concomitant with TOF, PDA, and bronchiectasia, as seen in our case, has a low incidence rate, and, moreover, such a case concomitant with pulmonary tuberculosis is rarer still.

Optimum conditions in the attenuated total reflection technique

In this paper the optimum condition for using the attenuated total reflection (ATR) technique is studied. In optimum conditions, the energy of an incident plane wave can be totally absorbed. The optimum condition can be realized by fabricating a localized thickness variation in the gap between a prism and a sample substrate with a point contact pressure. In the ATR technique, for example, the complex refractive index and the foil thickness of a thin metal foil, and the gap thickness are unknown parameters. To determine these unknown parameters, we prepared three prism coupling systems with different refractive indices. By this technique, we measured the complex refractive indices and the foil thicknesses of thin gold foils sputtered onto glass substrates, and the refractive index and the film thickness of a silica film sputtered onto a metal substrate.

Thickness measurement of ultrathin films on metal substrates using ATR

By modifying the surface plasma mode on a bare metal surface with an ultrathin film deposited on the metal, we measured the film thickness by attenuated total reflection (ATR). Various factors causing measurement errors are estimated with numerical examples. As a result, for example, it is shown that for some thicknesses, the errors due to the real part of the complex refractive index of a metal substrate become extremely small. Thicknesses of SiO(2) films sputtered onto Au foil and A1(2)O(3) films produced on Al foil by oxidation are measured.

Random-bend loss in single-mode and parabolic-index multimode optical fiber cables

Excess losses of single-mode and multimode cabled optical fibers due to random bends of the Gaussian correlation function are discussed theoretically. By comparing theoretical results of various correlation functions to measured excess losses of the cabled fibers, it is verified that the correlation function of random bends of single-mode and multimode cabled fibers is estimated to be Gaussian. Using the estimated Gaussian correlation function, random-bend loss formulas of the single-mode and the graded-index multimode fiber cables are given. To use a cabled single-mode fiber over a wider wavelength region intended for a wavelength-division-multiplexing system, the relative refractive-index difference between core and cladding should be made larger to reduce the random-bend loss substantially. Cabling losses of graded-index multimode fibers depend strongly on the relative refractive-index difference and the diameter of the core.

Reduction of resonancelike peak in direct modulation due to carrier diffusion in injection laser

It is shown theoretically that the relaxation oscillation in the direct modulation of the injection laser is reduced by transverse carrier diffusion when the stripe width is comparable to the carrier diffusion length. Modified rate equations are derived by considering the distribution of the light intensity, the carrier density, and the diffusion of the carrier. By small-signal analysis of the rate equations it is found that the height of the resonancelike peak in the modulation characteristics is a minimum when the transverse width in which both the light and the carriers are confined is around the diffusion length.