Charge Density Waves in YBa_{2}Cu_{3}O_{6.67} Probed by Resonant X-Ray Scattering under Uniaxial Compression.

We report a comprehensive Cu L_{3}-edge resonant x-ray scattering (RXS) study of two- and three-dimensional (2D and 3D) incommensurate charge correlations in single crystals of the underdoped high-temperature superconductor YBa_{2}Cu_{3}O_{6.67} under uniaxial compression up to 1% along the two inequivalent Cu─O─Cu bond directions (a and b) in the CuO_{2} planes. We confirm the strong in-plane anisotropy of the 2D charge correlations and observe their symmetric response to pressure: pressure along a enhances correlations along b, and vice versa. Our results imply that the underlying order parameter is uniaxial. In contrast, 3D long-range charge order is only observed along b in response to compression along a. Spectroscopic RXS measurements show that the 3D charge order resides exclusively in the CuO_{2} planes and may thus be generic to the cuprates. We discuss implications of these results for models of electronic nematicity and for the interplay between charge order and superconductivity.

The comparison of nasal surgery and CPAP on daytime sleepiness in patients with OSAS.

OBJECTIVE: Residual sleepiness after continuous positive airway pressure (CPAP) is a critical problem in some patients with obstructive sleep apnea syndrome (OSAS). However, nasal surgery is likely to reduce daytime sleepiness and feelings of unrefreshed sleep. The aim of this study is to clarify the effects of nasal surgery and CPAP on daytime sleepiness. METHODOLOGY: This is a retrospective and matched-case control study. The participants were consecutive 40 patients with OSAS who underwent nasal surgery (Surgery group) and 40 matched patients who were treated with CPAP (CPAP group). RESULTS: In the Surgery group, although the nasal surgery did not decrease either apnea or hypopnea, it improved oxygenation, the quality of sleep. In the CPAP Group, the CPAP treatment reduced apnea and hypopnea, and improved oxygenation, quality of sleep. The degree of relief from daytime sleepiness was different between the two groups. The improvement of Epworth Sleepiness Scale was more significant in the Surgery Group than those in the CPAP Group (Surgery from 11.0 to 5.1, CPAP from 10.0 to 6.2). DISCUSSION: These findings suggest that the results of the nasal surgery is more satisfactory for some patients with OSAS than CPAP on daytime sleepiness.

Characteristic oscillatory motion of a camphor boat sensitive to physicochemical environment.

A self-propelled camphor boat on water was investigated from the viewpoint of characteristic features of motion and mode-bifurcation depending on the diffusion length of camphor molecules. When a camphor disk was connected to the bottom of a larger plastic plate and then was placed on water, either oscillatory motion (repetition between rest and motion) or continuous motion was observed. In this paper, we report the novel features of this motion and mode-bifurcation as a function of the diffusion length of camphor molecules, e.g., multiple accelerations during oscillation, period-2 or irregular oscillatory motion, and reciprocating oscillation. These characteristic motion and mode-bifurcation are discussed in relation to the diffusion length of camphor molecules under the camphor boat and the development of camphor molecules from the camphor boat on water.

Prediction of oral appliance treatment outcome in obstructive sleep apnoea syndrome: a preliminary study.

OBJECTIVE: Predictors of treatment outcome of oral appliances (OAs) in patients with obstructive sleep apnoea syndrome (OSAS) are not known. There is a pressing need for simple, clinically useful tools to predict treatment outcome. This study aimed to identify predictors of successful OA therapy for OSAS, including evaluation of pharyngeal morphology, which can be measured during routine examination by an otorhinolaryngologist. METHODOLOGY: This was a prospective study of 26 OSAS patients treated with OAs. A favourable outcome was obtained in 14 patients (responders) but not in 12 patients (nonresponders). The baseline patient characteristics and polysomnography and rhinopharyngeal findings were analysed. RESULTS: Body mass index (BMI) was significantly lower in responders versus nonresponders (23.6 ± 2.8 vs. 27.9 ± 4.7 kg/m2; p < 0.05). Pharyngeal morphology, age, sex and nasal resistance did not differ between the groups. Multiple regression analysis showed that BMI was a significant predictor of improvement in the apnoea/hypopnoea index after OA treatment (p < 0.05). CONCLUSION: Here we demonstrated that BMI is a favourable predictor of OA treatment outcome in OSAS patients. Among the OSAS patients, responders had wider retroglossal spaces than nonresponders.

Using strain to uncover the interplay between two- and three-dimensional charge density waves in high-temperature superconducting YBa2Cu3Oy.

Uniaxial pressure provides an efficient approach to control charge density waves in YBa2Cu3Oy. It can enhance the correlation volume of ubiquitous short-range two-dimensional charge-density-wave correlations, and induces a long-range three-dimensional charge density wave, otherwise only accessible at large magnetic fields. Here, we use x-ray diffraction to study the strain dependence of these charge density waves and uncover direct evidence for a form of competition between them. We show that this interplay is qualitatively described by including strain effects in a nonlinear sigma model of competing superconducting and charge-density-wave orders. Our analysis suggests that strain stabilizes the 3D charge density wave in the regions between disorder-pinned domains of 2D charge density waves, and that the two orders compete at the boundaries of these domains. No signatures of discommensurations nor of pair density waves are observed. From a broader perspective, our results underscore the potential of strain tuning as a powerful tool for probing competing orders in quantum materials.

Morphological features of elderly patients with obstructive sleep apnoea syndrome: a prospective controlled, comparative cohort study.

OBJECTIVES: To investigate the pharyngeal morphologic features and its pathogenic role on obstructive sleep apnoea syndrome in the elderly population. DESIGN: Prospective controlled, comparative cohort study. SETTING: Territory referral centre. PARTICIPANTS: We enroled 320 consecutive patients with complaints of snoring who visited Nagoya University Hospital from January 2004 to December 2007. We also collected 26 control subjects aged over 60 years from community-dwelling people. MAIN OUTCOME MEASURES: We underwent a morphological evaluation, measurement of nasal resistance, assessment of daytime sleepiness and nocturnal polysomnography. RESULTS AND CONCLUSIONS: Two hundred and ninety-two patients were analysed. The constitution ratio of men, the body mass index and Epworth sleepiness scale were decreased with ageing. Tonsil size was reduced progressively with ageing. Retroglossal space was wider, and soft palate was lower in ≥ 60 year group than in < 40 year group. Retroglossal space was wide in elderly patients with sleep apnoea compared with control subjects. Tonsil size was not correlated to apnoea/hypopnoea index in ≥ 60 year group unlike the other generations. Modified Mallampati Score and tongue size were significantly but mildly correlated only in ≥ 60 year group. Width of fauces was correlated in all the groups. Multiple regression analysis showed that body mass index, age, gender, tonsil size and width of fauces were independent factors for apnoea/hypopnoea index. CONCLUSIONS: Morphologically, the tonsil could play a minor role but the width of fauces could play relatively a major role. Additionally, wide retroglossal space, low positional soft palate and large tongue size may be characteristics for elderly patients of obstructive sleep apnoea syndrome.

Relationship between the unilateral TMJ osteoarthritis/osteoarthrosis, mandibular asymmetry and the EMG activity of the masticatory muscles: a retrospective study.

The purpose of this retrospective study was to investigate the relationship between the unilateral temporomandibular joint (TMJ) osteoarthritis/osteoarthrosis (OA), mandibular asymmetry and electromyographic (EMG) activity of the masticatory muscles. Twenty-two Japanese women (aged 23.2 +/- 5.4 years) and 10 Japanese men (aged 22.4 +/- 2.8 years) exhibiting unilateral TMJ OA were included in this study. Two angular and seven linear measurements were obtained for the analysis of the skeletal hard tissues. The cephalometric measurement values (CV) were normalized using the CV ratio for the evaluation of the degree of mandibular asymmetry. The EMG was recorded during maximal voluntary clenching efforts for 10 s in the intercuspal position. The average values of integral EMG (iEMG) of three trials were normalized using the iEMG ratio for the evaluation of the functional balance of the masticatory muscles. The mandibular midline was shifted to the TMJ OA side with a median value of 9.85 mm. The CV ratio of the ramus height of the TMJ OA side was significantly smaller than that of the non-OA side. For the masseter muscle, the iEMG ratio of the TMJ OA side was significantly larger than that of the non-OA side (P < 0.05). These results suggest that unilateral TMJ OA is related to the dentofacial morphology, thus resulting in a mandibular midline shift to the affected side and it is associated with a masticatory muscle imbalance.

Localisation of basic fibroblast growth factor in cholesteatoma matrix: an immunochemical study.

OBJECTIVE: To investigate the expression of basic fibroblast growth factor in the matrix of human acquired cholesteatoma compared to the deep meatal skin. This topic does not appear to have been fully investigated before. METHODS: An immunochemical study was conducted. Cholesteatoma tissues from adult patients were collected during surgery (n = 19). Control specimens were taken from the deep meatal skin (n = 8) and compared. RESULTS: A highly significant difference in basic fibroblast growth factor expression was identified between cholesteatoma and skin (mean ± standard error = 58.53 ± 3.6 per cent in cholesteatoma vs 40.6 ± 3.5 per cent in skin; p = 0.005). Both basal and parabasal keratinocytes were stained positive with basic fibroblast growth factor. Additionally, there was specific staining in the basal columnar middle-ear epithelium and mast cell membrane. CONCLUSION: Basic fibroblast growth factor plays an active role in proliferative activity of cholesteatoma through its overexpression in basal and parabasal layers of cholesteatoma matrix. Moreover, its expression in the mast cell membrane supports its role in bone resorption activity.

Anemia-inducing substance from plasma of patients with advanced malignant neoplasms.

Patients with advanced malignant neoplasms develop anemia and immunosuppression. During an attempt to identify the causes, we have found that plasma from such patients makes RBCs more fragile in hypotonic buffer, according to results obtained with a coil planet centrifuge. Plasma from these patients suppresses mitogen-stimulated lymphocyte proliferation. In this study, we identified the substance with these effects as a protein. During two-dimensional gel electrophoresis, two isomers with M(r) 50,000 and slightly different isoelectric points near 6.0 were found. Cell fractionation showed that these proteins were in both the cytosol and the nuclear fraction of cells in neoplasms. Another protein with the same antigenicity and a M(r) 100,000 found in the nuclear fraction of cells in neoplasms.

Applicability of micro-channel plate followed by phosphor screen to charged particles.

This paper experimentally investigates the applicability of a micro-channel plate (MCP) followed by a phosphor screen to charged particles along with a calibration method for estimating the acceptable limit of input particle flux and appropriate operation parameters of a particular MCP. For the first time, plasmas consisting of only lithium ions are injected into the MCP. Despite large ion numbers (Ni) on the order of ≃10(7), no deterioration in the effective gain (αG) of the MCP owing to an excess amount of the extracted charge occurs in a certain range of the amplifier voltage (ΔUM) applied to the MCP. The measured αG nearly agrees with the expected value. However, once ΔUM exceeds a limit value, αG eventually begins to saturate. This is also verified in experiments using pure electron plasmas. An appropriate range of ΔUM is presented to avoid saturation and, finally, derive Ni directly from the secondary electron current outputted from the MCP only after the indispensable calibration.

Evidence that graft coronary arteriosclerosis begins in the early phase after transplantation and progresses without chronic immunoreaction. Histopathological analysis using a retransplantation model.

The histopathological features of chronic rejection and its initiation were assessed using rat heterotopic heart transplantation and retransplantation models. Fully allogeneic or minor, non-MHC antigen-mismatch heart grafts transplanted into recipient rats treated with a short course of FK506 showed long-term survival but developed graft atherosclerosis after 40 days posttransplantation. Retransplantation of allografts back into the original donor strain did not prevent graft atherosclerosis if the grafts had resided in the primary recipient for up to 5 days; residence in the primary allogeneic recipient for less than 4 days did not result in graft atherosclerosis in the secondary recipient. Short-course administration of FK506 did not affect the production of these changes. Graft coronary arteriosclerosis begins between 3 and 5 days posttransplantation and progresses without continuous allogeneic immunological drive. The present findings will provide a new means by which to approach the analysis of development of chronic allograft rejection.

Analysis of rejection mechanism in the rat to mouse cardiac xenotransplantation. Role and characteristics of anti-endothelial cell antibodies.

Recent reports have demonstrated that humoral factors, especially antibodies elicited by xenoantigens, play an important role in the rejection of concordant cardiac xenografts. These induced antibodies, however, have not been well characterized. Therefore, we investigated the rejection mechanism, especially the role of humoral immunological responses in the concordant rat to mouse cardiac xenograft model. Lewis rat hearts transplanted into C3H/HeN mice were rejected in 5-6 days. The essential role of humoral factors in the rejection was demonstrated by histological analysis of the rejected hearts showing interstitial hemorrhage, scant cellular infiltration, and the dense deposition of mouse IgG, IgM, and C3 on the graft endothelial cells. In addition, mice that received hyperimmune serum (serum at the 10th day after transplantation) rejected rat hearts hyperacutely. Flow cytometrical analysis using cultured donor rat coronary endothelial cells demonstrated the xenoreactive antibodies of all subclasses, but especially strong reactivity of IgM and IgG2a in the serum at rejection. These xenoreactive antibodies were produced against not only MHC, but also non-MHC antigens on graft endothelial cells. In vivo depletion of L3T4+ T cells led to the suppression of xenoreactive antibody production and the prolongation of graft survival, indicating that antibody production in this model needs L3T4+ T cell help.

The mechanism of discordant xenograft rejection.

The mechanism of discordant xenograft rejection using the guinea pig-to-rat heart graft model was studied. In this model, we found that (A) Rejection occurred rapidly, in 17.5 +/- 8.3 min (mean +/- SD) (n = 8). (B) The graft survived longer when the recipient rat was pretreated with cobra venom facter (CVF). (C) Complement hemolytic titers in serum showed significant reduction of C3 in rejection without consumption of C4 and C2, suggesting complement activation through the alternative pathway. (D) No natural antibodies were detected in this combination. Complement-dependent cytotoxicity (CDC) titer, and hemagglutination (HA) titer were lower than x1. (E) Histological examination of the rejected heart xenograft revealed a large area of myocytolysis without interstitial cellular infiltration. (F) In vitro experiments showed that rat complement attacked guinea pig erythrocytes (Egp) via the alternative pathway. These findings indicate that rejection in this discordant xenograft model of guinea pig-to-rat was caused by primary activation of complement via the alternative pathway.

Donor-specific tolerance by perioperative intrathymic injection of bone marrow cells in the rat cardiac allograft model: use of FK506 can shorten the necessary duration of pretransplant intrathymic conditioning.

BACKGROUND: Many strategies of tolerance induction by intrathymic (IT) injection of donor alloantigens have been reported to date; however, the timing of IT injection is usually 1-3 weeks before transplantation. METHODS: To apply IT injection to cadaveric organ transplantation, 1 x 10(8) fully allogeneic bone marrow cells (BMC) of Buffalo (BUF; RT1b) rats were intrathymically injected into Wistar Furth (WF; RT1u) rats at the time of BUF cardiac allografting with short-course therapy of antilymphocyte serum (ALS) and FK506 in our experimental model. RESULTS: Allogeneic IT injection of BUF BMC with ALS and FK506 indefinitely prolonged graft survival (mean survival time > 210 days) in all WF rats. On day 130 after grafting, tolerant WF rats accepted donor BUF skin grafts (> 120 days) but not third-party Lewis skin grafts. In control groups, syngeneic IT injection of WF BMC or intravenous injection of donor BUF BMC in combination with ALS/FK506 therapy failed to induce tolerance. In vivo testing was performed during induction (1 month) or during maintenance (6 months of tolerance. In the mixed lymphocyte reaction (MLR), spleen T cells of tolerant rats at 1 month after grafting displayed hyporesponsiveness after stimulation with donor cells. The addition of interleukin (IL)-2 to MLR culture did not restore T-cell responsiveness. Tolerant rats had a significantly decreased frequency of T cytotoxic cell precursors (fTcp) of 1:4,926, and frequency of IL-2-producing T helper cell precursors (fThp) of 1:23,925, compared with naive rats (1: 2,158 and 1:4,266, respectively). By 6 months after grafting, however, the anti-donor MLR proliferative responses of tolerant rats had been restored to the levels of naive splenic T cells. These tolerant rats displayed restoration of the (fTcp) of 1:2,842 and of the (fThp) of 1:5,630, which were comparable frequencies of naive rats. Suppressor T cells did not contribute in this model. In cardiac grafts of tolerant rats induced by IT injection, expression of both Th1 (interferon-gamma and IL-2) and Th2 (IL-4 and IL-10) cytokines was detected in the early phase; thereafter, expression was completely inhibited, except for interferon-gamma in the chronic phase. CONCLUSIONS: Perfect donor-specific tolerance was obtained by IT injection of donor BMC at the time of transplantation, while alloimmune responses were maintained at levels similar to those of naive rats.

Myocardial energy metabolism in asphyxiated canine hearts preserved for 24 hours.

Myocardial energy metabolism in asphyxiated cadaver hearts preserved in UW solution (UWS; group 1, n = 6) or modified Collins' solution (MCS; group 2, n = 6) was compared with that in cardioplegic arrested hearts immersed in ice-cold MCS with (group 3, n = 6) or without myoprotective drugs (group 4, n = 5). All hearts were stored for 24 hr. The hearts in groups 1 and 2 were pretreated with prostacyclin, verapamil, and propranolol; asphyxiated for 10 min, reversed by coronary perfusion with warm blood cardioplegia (WBCP); perfused with ice-cold crystalloid cardioplegia for 2 hr; excised and immersed in cold storage solution for 22 hr; and perfused again with WBCP before reperfusion. ATP contents were measured in biopsy specimens by HPLC. Myocardial ATP level decreased significantly from 23.7 +/- 1.7 to 15.9 +/- 2.5 mumol/g dry wt. (P less than 0.0001) by asphyxia, but recovered to within normal limits by WBCP in group 1. The ATP level again decreased to 15.8 +/- 2.4 mumol/g dry wt. during 24-hr storage, but finally rose to 22.4 +/- 3.5 mumol/g dry wt. by terminal WBCP. The ATP metabolism in group 2 was similar to that in group 1. The ATP content in group 4 was significantly lower than that in other groups (P less than 0.01) after 24-hr preservation. The study shows that damage to cadaver hearts can be reversed and the hearts maintained satisfactorily viable for 24 hr.

Prolonging discordant xenograft survival with anticomplement reagents K76COOH and FUT175.

The guinea pig heart, when transplanted into the rat heterotopically, is rejected within 30 min via activation of the alternative complement pathway. Natural antibody does not contribute to rejection. This xenotransplantation model was used to assess the effect of anti-complement reagents on discordant xenograft survival. In vivo administration of K76COOH (K76) to rats induced only slight suppression of factors B and D and a marked decrease of C3, leading to the depression of ACH50 (reflecting the potency of the alternative pathway). On the other hand, FUT175 (FUT) reduced C3 activity by about 80% and inhibited factor B activity nearly 100% < 1 hr after the administration, but inhibited factor D activity only marginally. FUT abrogated ACH50 for > 6 hr. Of note, the xenograft beating time was prolonged approximately 3 times by FUT but not by K76, suggesting that direct inhibition of plasma serine protease factor B results in the complete suppression of ACH50 and graft survival. The administration of both K76 and FUT resulted in the longest graft survival, but the effects of these reagents were abolished by additional antigraft antibody. Anticomplement reagents that block factor B and C3 are therefore effective for prolongation of discordant xenograft survival when the graft rejection is associated with the complement alternative pathway.

Effects of transfected complement regulatory proteins, MCP, DAF, and MCP/DAE hybrid, on complement-mediated swine endothelial cell lysis.

We established several swine endothelial cell (SEC) lines, expressing human MCP (CD46), DAF (CD55), and MCP/DAF hybrid by transfection of cDNA, and assessed the function of these transfectant molecules on complement-mediated cell lysis as an in vitro hyperacute rejection model of swine to human discordant xenograft. Discordant organ xenografts are hyperacutely rejected by complement activation. Amelioration of complement-mediated lysis by these transfectant molecules was tested in each SEC line by lactate dehydrogenase assay. Naive swine endothelial cells were markedly damaged by human complement mainly via the classical pathway, activating only minimally the alternative pathway of human complement. Both MCP and DAF protected SEC from human complement attack in parallel with the expression density, with DAF being more effective than MCP. The MCP/DAF hybrid was more effective than MCP alone, and as effective as DAF in this system. The results suggest that the transfection of DAF or the MCP/DAF hybrid cDNA into organs to be transplanted could protect against hyperacute rejection.

The rejection mechanism of rat pancreaticoduodenal allografts with a class I MHC disparity.

The present study has demonstrated for the first time that PVG.R1 (RT1.AaBcDcCc) pancreatic grafts are rejected by so-called "low"-responder PVG (RT1.AcBcDcCc) recipients with an isolated class I MHC disparity (mean survival time; MST: 21.4 +/- 1.8 days, n = 5), whereas PVG.R1 heart grafts are able to survive indefinitely (MST: > 100 days, n = 5). Splenic CD4+ T cells but not CD8+ T cells from the PVG recipients of PVG.R1 pancreatic grafts show a remarkable proliferative response against donor class I RT1.Aa alloantigens, while only a minimal proliferation is observed in the PVG recipients of PVG.R1 heart grafts or naive PVG rats. Naive PVG rats display an extremely low frequency of IL-2-producing helper T cell precursors (fThp) of 1/40,609 +/- 15,441 against class I RT1.Aa alloantigen. The PVG recipients of PVG.R1 heart grafts have a slightly greater fThp of 1/17,326 +/- 6822. On the other hand, the PVG recipients that rejected PVG.R1 pancreatic grafts show a significantly increased fThp of 1/5030 +/- 3396 compared with those of PVG.R1 heart grafts (P < 0.05) or naive PVG rats (P < 0.01). The frequency of cytotoxic T cell precursors (fTcp) increases slightly in the PVG recipients of PVG.R1 pancreatic grafts (1/1848 +/- 330) compared with those of PVG.R1 heart grafts (1/2215 +/- 2131) or naive PVG rats (1/2476 +/- 585). The size of cytotoxic T cell clones alone does not adequately account for a proliferation sufficient to complete the rejection of pancreatic grafts. The PVG recipients of PVG.R1 pancreatic grafts, but not heart grafts, demonstrate a strong cytotoxic alloantibody response to donor class I RT1.Aa alloantigens. In the study of alloantibodies, IgM is detected mainly in the early phase and IgG in the late phase during the course of pancreatic rejection. It is determined that in blocking studies by FACS analysis these antibodies target class I MHC antigens. These results suggest that cytotoxic T cells do not appear to be responsible for the rejection of PVG.R1 pancreatic grafts in PVG recipients. Rather, the rejection is mediated by CD4+ T cells and complement-fixing antibodies directed at class I MHC antigens.

Hyperactivity of 99mTc-HMPAO within 6 hours in patients with acute ischemic stroke.

UNLABELLED: Intraarterial thrombolytic therapy has been used recently for treatment of acute ischemic stroke within 6 h after onset. Although hypoactivity of 99mTc-hexamethylpropyleneamine oxime (HMPAO) in stroke has been well documented, hyperactivity of HMPAO has not been evaluated in sufficient detail. The purpose of this study was to evaluate the incidence and clinical importance of hyperactivity of HMPAO in management of patients with acute ischemic stroke. METHODS: We retrospectively investigated HMPAO SPECT in 90 patients with acute ischemic stroke within 6 h after onset. The lesion-to-contralateral radioactivity ratios (L/Cs) were calculated on the SPECT images before treatment and were compared with the imaging results of CT or MRI (or both). RESULTS: Hyperactivity of HMPAO, accompanied by surrounding hypoactivity, was observed in 6 of 90 patients (7%) within 6 h after onset. The L/Cs ranged from 1.17 to 2.95. Two patients showed hyperactivity in the cortex and the other 4 patients showed hyperactivity in the basal ganglia. Angiography confirmed spontaneous recanalization of occluded vessels in accordance with the area of hyperactivity. In both patients with cortical hyperactivity, cerebral infarctions were revealed on follow-up CT; in 1 patient, hemorrhagic transformation developed after intraarterial thrombolytic therapy. In 3 of the 4 patients with hyperactivity in the basal ganglia, follow-up CT showed no infarction in the surrounding hypoperfused cortex (selective intraarterial thrombolytic therapy was performed on 2 patients), although various degrees of infarction were observed in the basal ganglia. Obvious infarctions developed in the basal ganglia and the cortex of the other patient. CONCLUSION: Hyperactivity of HMPAO could be seen in the basal ganglia and the cortex within 6 h after onset, reflecting spontaneous recanalization. The areas of hyperactivity may develop infarctions, whereas the accompanying areas of hypoactivity could be rescued by selective intraarterial thrombolytic therapy.

Measurement of severity of aortic stenosis experimentally produced in dogs without inserting a catheter into the left ventricle.

When flow passes through an orifice, pressure loss does not occur in the laminar core of the jet distal to the stenosis, but occurs in the region more distal to the stenosis, where the laminar core disappears and turbulence develops. Therefore, if total pressure is measured in the laminar core of the jet some distance downstream of a stenotic aortic valve, it should be equal to total pressure on the left ventricular side of the aortic valve. An experimental study was performed in 5 dogs to test this hypothesis. The results revealed that left ventricular pressure during the ejection period can be determined by measuring the pressure in the laminar core. A preliminary evaluation of the clinical applicability of our method was performed during catheterization in a patient with severe aortic valve stenosis. In this case, the pressure obtained in the jet downstream of the aortic valve was slightly lower than that obtained in the left ventricle.