MR imaging of benign and malignant lesions in the buccal space

OBJECTIVES

To evaluate MRI characteristics of buccal space lesions and to discuss the sensitivity of MRI in predicting malignancy of those lesions.

METHODS

Thirty patients with malignant (n=7) or benign (n=23) lesions originating in the buccal space were reviewed retrospectively. MR images were assessed for the margins, internal architecture, signal intensity of lesions and their relation to the surrounding structures.

RESULTS

Two cases of soft tissue sarcoma were shown as ill-defined masses with infiltration into adjacent muscles and bone. On the other hand, all tumors of minor salivary gland origin, whether malignant (n=4) or benign (n=2), were well-defined and confined within the buccal fat pad without infiltration into surrounding structures. All haemangiomas (n=9) had very high T2-weighted signal intensity. Three out of them contained signal voids on all sequences thought to represent phleboliths, a finding strongly suggestive of the diagnosis. Inflammatory lesions were characterized by the presence of edema in the surrounding fat. When ill-defined margins, infiltration into muscles and bone destruction were used as the criteria for the malignancy, only two out of seven malignant tumors were correctly diagnosed (sensitivity 29%).

CONCLUSIONS

Although MR imaging was useful in demonstrating the extent of buccal space lesions, its diagnostic value in predicting malignancy was very limited. It was especially true for malignant tumors of minor salivary gland origin, which were typically seen as well-defined masses without infiltration into surrounding structures on MRI.

Zernike-type X-ray imaging microscopy at 25 keV with Fresnel zone plate optics

A Zernike-type imaging microscope using a sputtered-sliced Fresnel zone plate (SS-FZP) has been developed and tested at an X-ray energy of 25 keV. The SS-FZP was used as an objective. A copper (Cu) phase plate was placed at the back focal plane of the SS-FZP in order to produce phase contrast. The performance of the Zernike-type imaging microscope was tested with a gold (Au) mesh and a resolution test pattern at undulator beamline 47 of SPring-8. The Au mesh and the resolution test pattern could be imaged in transmission with a magnification of x10.2. Owing to the Cu phase plate, different image contrast was observed compared with the bright-field image contrast. Tantalum microstructures down to 0.5 microm line-and-space have been observed on spatial resolution test patterns.

Development of a multilayer Fresnel zone plate for high-energy synchrotron radiation X-rays by DC sputtering deposition

Hard X-ray microscopy with high spatial resolution (<or=0.1 microm) using a high-energy and high-brilliance X-ray microprobe is expected to be a promising technology for various types of analysis, imaging etc. in materials science, biology and medicine. A multilayer Fresnel zone plate (FZP) could be a promising approach to focusing optics in the high-energy X-ray region (>or=20 keV) because a large thickness (aspect ratio) can be available. Various types of multilayer FZPs have been fabricated by DC sputtering deposition. Their focusing characteristics have been evaluated at the high-brilliance undulator beamline BL47XU of SPring-8. An optical system using a Cu/Al multilayer FZP (with an outermost zone width of 0.25 microm) as the focusing optics fabricated by the optimum deposition condition with precise film (zone) thickness control has attained an almost diffraction-limited microbeam of 0.3-0.35 microm at 8.9 keV. A line-and-space resolution test pattern has been observed: fine structures up to 0.2 microm were clearly observed in the measured image. This FZP has been working since 1995, keeping good focusing characteristics. It can be said from these results that a spatial resolution better than 0.1 microm in the high-energy X-ray region is in prospect by the development of a multilayer FZP with a narrower outermost zone width in the near future.

MR detection of iliac bone marrow involvement by malignant lymphoma with various MR sequences including diffusion-weighted echo-planar imaging

OBJECTIVE

To assess the diagnostic accuracy of MR imaging for detecting bone marrow infiltration by malignant lymphoma.

PATIENTS AND DESIGN

Fifty-three patients with malignant lymphoma underwent MR imaging and bone marrow biopsy. In 80 iliac crests of the 53 patients (13 positive specimens in 9 patients and 67 negative specimens in 44 patients), biopsy results and the signal intensity characteristics were compared. MR sequences included T1-weighted SE, T2-weighted FSE with fat suppression, FSE STIR, and diffusion-weighted EPI with fat suppression at 1.5 T.

RESULTS AND CONCLUSIONS

To detect lymphoma infiltration, T1-weighted SE had the highest sensitivity (92%) and diffusion-weighted EPI with fat suppression and FSE STIR had the highest specificity (92.5% and 92%, respectively). A combination of T1-weighted SE and FSE STIR yielded the highest sensitivity and specificity (85% and 97%, respectively). A combination of T1-weighted SE and FSE STIR sequences seems to be the current choice of imaging protocol for detecting bone marrow infiltration by malignant lymphoma.

Hard X-ray microbeam experiments with a sputtered-sliced Fresnel zone plate and its applications

Hard X-ray microbeam experiments with sputtered-sliced Fresnel zone plates have been performed. Zone plates with an outermost zone width of 0.25 microm (#FZP1) and 0.1 microm (#FZP2) were fabricated and evaluated. In a scanning X-ray microscopy experiment, a line-and-space pattern with structure as fine as 0.1 microm was resolved using #FZP2 at an X-ray wavelength of 1 A. As an application of the microbeam technique, a two-dimensional distribution of constituent elements in forensic samples has been obtained (e.g. section view of human and elephant hairs) using fluorescent scanning microscopy.

Sonographic appearances of malignant lymphoma of the salivary glands

PURPOSE

We undertook this retrospective study to describe the sonographic findings in patients with malignant lymphoma of the major salivary glands.

METHODS

We reviewed the sonograms and medical records of 7 patients with histologically proven lymphoma of the parotid (3 patients) or submandibular glands (4 patients).

RESULTS

Primary lymphoma was found in 1 parotid gland and 2 submandibular glands. The remaining 4 cases were secondary lymphomas. One patient had been diagnosed with Sjögren's syndrome and had been followed up with sonography. In parotid glands, both parenchymal and intraparotid nodal lymphomas were found. All submandibular gland tumors were parenchymal. Intraparotid nodal involvement appeared as multiple small nodules with relatively smooth margins, whereas the parenchymal parotid and submandibular gland lymphomas were larger (25 to 45 mm in longitudinal diameter) and showed various degrees of margin irregularity. All tumors were hypoechoic relative to the normal parenchyma. The primary parotid lymphoma and intraparotid nodal lymphomas had a homogeneous echotexture; the secondary parotid lymphomas and submandibular gland lymphomas were heterogeneous. One submandibular gland lymphoma showed intratumoral echogenic stripes. Neither calcification nor cystic degeneration was observed within the lesions.

CONCLUSIONS

Lymphomas of the salivary glands present a variety of sonographic appearances, ranging from multiple small, hypoechoic nodules to an irregularly shaped heterogeneous mass without cystic areas or calcifications.

Relationship between bone marrow cellularity and apparent diffusion coefficient

This study was performed to determine if there is a relationship between apparent diffusion coefficient (ADC) and cellularity of bone marrow of the posterior ilium. Four groups of various marrow cellularity underwent diffusion-weighted echo-planar imaging: 1) adults with normal hypocellularity (21 patients); 2) adults with normal normocellularity (13 patients); 3) young children with normal hypercellularity (5 patients); and 4) adults with lymphoma-related hypercellularity (3 patients). In all adults, marrow cellularity was confirmed by uni-or bilateral bone marrow biopsies. In children, the iliac marrow was presumed hypercellular because of their ages. A total of 66 ADC values of bone marrow calculated from diffusion-weighted images with b-values of 30 and 300 seconds/mm(2) was evaluated. Hypercellular marrow (normal and lymphoma-related) showed the highest mean ADC, and hypocellular the lowest ADC. Statistically significant differences were found between three groups of normal marrow: hypocellular, normocellular, and hypercellular. There is a positive correlation between ADC and cellularity of bone marrow. J. Magn. Reson. Imaging 2001;13:757-760.

MRI of ranulas

We reviewed the MRI of 20 patients with a ranula (8 simple and 12 plunging) and ten with other cystic masses in the floor of the mouth and/or suprahyoid portion of the neck (three haemangiomas, two neuromas, one monomorphic adenoma, one lipoma, two lateral cervical cysts and one dermoid cyst). Histological diagnoses were obtained in all cases with the exception of one presumed haemangioma. Ranulas were all well-defined, homogeneous masses giving low signal on T1- and markedly high signal on T2-weighted images. While simple ranulas were all confined to the sublingual space, plunging ranulas were centered on the submandibular space and tended to spill into one or more adjacent spaces. They extended into the sublingual space anteriorly (producing a so-called tail sign) in eight of 12 cases and into the parapharyngeal space superiorly in five. Although they sometimes filled a considerable part of the parapharyngeal space, displacement of surrounding muscles or vessels was usually slight, which was thought to reflect the nature of extravasation pseudocysts. All other cystic masses in our study had one or more MRI finding different from those of ranulas and could be easily differentiated from them.

New terpenoid components from the volatile oils of the soft corals Clavularia viridis and Sarcophyton acutangulum

A new tetracyclic terpenoid hydrocarbon, cyclosinularane (1), and (+)-alloaromadendrene (2), the enantiomer of terrestrial (-)-alloaromadendrene, have been isolated from the volatile oil of the soft corals Clavularia viridis and Sarcophyton acutangulum, respectively. Their structures have been determined on the basis of NMR spectral analysis and their chiroptical properties.

Primary malignant lymphoma of the maxillary sinus: CT and MRI

We reviewed the CT and MRI of seven patients with primary malignant lymphoma of the maxillary sinus to find if there are characteristic imaging findings suggestive of the disease. The images were analysed for appearance, size, signal, internal characteristics, extent of tumour, bone change and lymph node enlargement. In two patients, the tumour first presented with mucosal thickening. In the remaining five, the tumours were an expansile mass 4-6 cm in diameter at the time of detection. Although it was difficult to distinguish tumour from mucosa or obstructed fluid on CT, T2-weighted MRI enabled us to separate tumour from normal mucosa or fluid. In two patients, the tumours were heterogeneous. Calcification and haemorrhage were observed in one patient. Periantral soft-tissue infiltration was always present, even when tumour appeared as slight mucosal thickening. Posterior extension was seen in all patients. Permeative and lytic bone destruction accompanied most cases of periantral soft-tissue infiltration; mixed destruction and sclerosis was also observed. Mucosal thickening with periantral soft-tissue infiltration may suggest malignant lymphoma of the maxillary sinus in its early form. Various types of bone change may accompany the periantral soft-tissue infiltration.

Recurrent pleomorphic adenoma of the head and neck

We reviewed the clinical and imaging files of 15 patients with pathologically confirmed recurrent pleomorphic adenomas of the head and neck. The primary tumours were in the lacrimal gland (1 case), cheek (2), palate (5), parotid gland (4), and submandibular gland (3). Recurrence was generally late, with an average of 14.9 years between initial surgery and recurrence. Multiple recurrent tumours, measuring 5-50 mm were found in eight patients. In all palatal cases recurrence was large and solitary. Most recurrent pleomorphic adenomas were well delineated with smooth margins, like most primary tumours. Irregularity of the margins was seen in four patients. In four of the five tumours of the palate and in the orbital lesion, the recurrent tumours caused bone destruction, thus mimicking malignant lesions. Irregular-margined recurrences seem to be rather small and found among multiple recurrent nodules.

Identification of HLA-A24 epitope peptides of carcinoembryonic antigen which induce tumor-reactive cytotoxic T lymphocyte

Carcinoembryonic antigen (CEA), which is expressed in several cancer types, is a potential target for specific immunotherapy. HLA-A24 is the most frequent allele among Japanese and is also frequently present in Asians and Caucasians. We tested CEA-encoded HLA-A24 binding peptides for their capacity to elicit anti-tumor cytotoxic T lymphocytes (CTL) in vitro. For this purpose, we used CD8+ T lymphocytes from peripheral blood mononuclear cells (PBMC) of a healthy donor and autologous peptide-pulsed dendritic cells as antigen-presenting cells. This approach enabled us to identify 2 peptides, QYSWFVNGTF and TYACFVSNL, which were capable of eliciting CTL lines that lysed tumor cells expressing HLA-A24 and CEA. The cytotoxicity to tumor cells by the CTL lines was antigen-specific since it was inhibited by peptide-pulsed cold target cells as well as by anti-class I major histocompatibility complex (MHC) and anti-CD3 monoclonal antibodies (MAbs). The antigen specificity of the 2 CTL lines was examined using several tumor cell lines of various origins and for their peptide-dose responses. The identification of these novel CEA epitopes for CTL offers the opportunity to design and develop epitope-based immunotherapeutic approaches for treating HLA-A24+ patients with tumors that express CEA.

Identification of HLA-A24 epitope peptides of carcinoembryonic antigen which induce tumor-reactive cytotoxic T lymphocyte

Carcinoembryonic antigen (CEA), which is expressed in several cancer types, is a potential target for specific immunotherapy. HLA-A24 is the most frequent allele among Japanese and is also frequently present in Asians and Caucasians. We tested CEA-encoded HLA-A24 binding peptides for their capacity to elicit anti-tumor cytotoxic T lymphocytes (CTL) in vitro. For this purpose, we used CD8+ T lymphocytes from peripheral blood mononuclear cells (PBMC) of a healthy donor and autologous peptide-pulsed dendritic cells as antigen-presenting cells. This approach enabled us to identify 2 peptides, QYSWFVNGTF and TYACFVSNL, which were capable of eliciting CTL lines that lysed tumor cells expressing HLA-A24 and CEA. The cytotoxicity to tumor cells by the CTL lines was antigen-specific since it was inhibited by peptide-pulsed cold target cells as well as by anti-class I major histocompatibility complex (MHC) and anti-CD3 monoclonal antibodies (MAbs). The antigen specificity of the 2 CTL lines was examined using several tumor cell lines of various origins and for their peptide-dose responses. The identification of these novel CEA epitopes for CTL offers the opportunity to design and develop epitope-based immunotherapeutic approaches for treating HLA-A24+ patients with tumors that express CEA.

Increase in memory (CD4+CD29+ and CD4+CD45RO+) T and naive (CD4+CD45RA+) T-cell subpopulations in smokers

To examine the effects of smoking on lymphocyte subpopulations, we measured the following cell subpopulations: CD4+ T-cell subpopulations (i.e., CD4+CD29+, CD4+ CD45RO+, and CD4+CD45RA+ cells); CD8+ T-cell subpopulations (i.e., CD8+CD11a+ and CD8+CD11b+ cells); and natural killer cell subpopulations (i.e., CD16+CD57-, CD16+CD57+, and CD16-CD57+ cells). We measured these subpopulations, together with total CD4+ T, total CD8+ T, total CD3+ T, B (CD19+), and total lymphocytes, in 10 male heavy smokers, 38 male light-to-moderate smokers, and 33 male nonsmokers. The mean ages were 30 y, 31 y, and 32 y, respectively, and ages did not vary significantly among the smokers. CD4+CD29+ and CD4+CD45RO+ (memory T) cells in heavy smokers were significantly more numerous than those in light-to-moderate smokers and nonsmokers. Also, these memory T-cell subpopulations were significantly more numerous in light-to-moderate smokers than in nonsmokers. The number of CD4+CD45RA+ (naive T) cells was significantly larger in heavy smokers than nonsmokers; numbers of CD4+CD45RO+ T and CD4+CD29+ T cells (memory T cells) were significantly correlated with daily cigarette consumption. Numbers of CD3+ T, CD4+ T, CD19+ B, and total lymphocytes in heavy smokers were significantly larger than in nonsmokers. There were significantly more CD3+ T, CD4+ T, and total lymphocytes in light-to-moderate smokers than in nonsmokers. The numbers of CD4+ T lymphocytes in heavy smokers were significantly larger than in light-to-moderate smokers. Perhaps CD4+ T cell subpopulations, especially memory T cells, are most susceptible to the effects of smoking on lymphocyte subpopulations.

Synthesis and antiallergic activity of dimethyl-2-(phenylcarbamoyl)ethylsulfonium p-toluenesulfonate derivatives

The derivatives of dimethyl-2-(phenylcarbamoyl)ethylsulfonium p-toluenesulfonates were synthesized and evaluated for antiallergic activity. The 2,3-dihydroxyethoxy group was introduced to the phenyl ring from the standpoint of lipophilicity and electronic effects of substituent. The IgE-induced rat passive cutaneous anaphylaxis (PCA) was inhibited by oral administration of several substituted 2-[(4-propoxyphenyl)carbamoyl]ethyldimethylsulfonium p-toluenesulfonate derivatives. Among them (+/-)-2-[N-[4-(3-ethoxy-2-hydroxypropoxy)phenyl]carbamoyl]ethyldimeth ylsulfonium p-toluenesulfonate (1a, IPD-1151T) was found to possess considerable activity in the PCA test, and it was launched as Suplatast tosilate in Japan.

Malignant lymphoma of the gingiva: MR evaluation

PURPOSE

Our purpose was to document the MR imaging findings of malignant lymphoma of the gingiva.

METHODS

Five patients with histologically proved malignant lymphoma of the gingiva were studied by MR imaging. The MR images were analyzed for tumor size, extent, and signal characteristics, bone involvement, and associated cervical lymph node enlargement.

RESULTS

Clinical examination tended to underestimate the size of lymphomatous lesions. The signal intensity of the lesions was isointense to hyperintense relative to muscle on noncontrast T1-weighted images and showed variable contrast enhancement patterns. On T2-weighted images, signal intensity was isointense to hypointense relative to the oral mucosa. In one case, the mass extended to the submandibular space; in the remaining cases, the masses were limited to the gingiva and the adjacent bone. MR imaging revealed that gingival lymphomatous masses were broad-based along the mandible or maxilla and eroded through the cortex into the marrow space, but the cortex was still recognizable. No nodal involvement was noted in any of the patients with malignant lymphoma.

CONCLUSION

The signal characteristics of gingival lymphoma overlap those of other tumors. The cortex separating marrow involvement from the broad-based gingival mass generally appears to be permeated with small erosions but is still recognizable.

Rupture of the left main-stem bronchus by the tracheal portion of a double-lumen endobronchial tube

We report a rupture of the left main-stem bronchus following the insertion of a left-sided double-lumen endobronchial tube in a 76-yr-old woman with a short trachea. A fiberoptic bronchoscope was not used during the initial insertion of the tube and the depth of insertion resulted in approximately 5 cm in excess of the optimal level for this patient. The rupture had been caused by the tracheal portion of the double-lumen tube. This damage may have been avoided if a fiberoptic bronchoscope was used routinely as an introducer and for positioning of the endobronchial tube under direct vision.

[Anesthetic management of a patient with tuberous sclerosis]

Tuberous sclerosis is characterized by facial angiofibromatosis, epilepsy, and mental retardation. There have been only a few reports of anesthetic management of patients with tuberous sclerosis. We managed a 22-year-old patient with tuberous sclerosis using nitrous oxide (67%) in oxygen supplemented with fentanyl and midazolam. There were no untoward events related to anesthesia and surgery. Problems in managing patients with tuberous sclerosis are also discussed.

The relation between an esophageal cancer and associated cancers in adjacent organs

BACKGROUND

The relation between esophageal cancers and head and neck tumors was studied in order to improve the treatment results in patients with multiple cancers.

METHODS

We reviewed the records of 3,375 patients with an indexed squamous cell carcinoma of the head and neck treated at our institution between 1960 and 1994; and 81 patients were found to have an associated esophageal carcinoma. Similarly, the records of 434 patients with an indexed esophageal cancer were reviewed; and 54 patients had cancers in other organs or in the residual esophagus. A total of 135 esophageal cancers with 154 synchronous or metachronous cancers were entered into the analysis.

RESULTS

The risk of developing esophageal cancer was ten times higher in male patients with head and neck cancer than in female patients. Synchronous or metachronous esophageal cancer associated with head and neck cancer was most frequently seen with pharyngeal cancer (28/360 = 7.8%), followed by in the oral cavity (47/2148 = 2.2%).

CONCLUSIONS

Better knowledge of the relation between an esophageal cancer and a head and neck cancer may lead to the early detection of subsequent small, potentially curable neoplasms sited in either the esophagus or the head and neck region.

External and interstitial radiotherapy in the treatment of oropharyngeal squamous cell carcinoma

The records of 165 patients with squamous cell carcinoma of the oropharynx treated at our hospital with external and/or interstitial radiotherapy between 1971 and 1990 were reviewed to evaluate the treatment results, focusing on primary control and complications. All cancers were restaged according to the UICC 1987 TNM staging system. Of these 165 patients, 11% were in Stage I, 55% in Stage II, 24% in Stage III and 8.5% in Stage IV. Local control and complications were analysed in 140 patients. The remaining 25 patients died of intercurrent or metastatic disease during the first 2 years following treatment and were excluded from the analysis. 70 patients were treated by interstitial implant using permanent implant seeds (Rn-222 in eight patients, Au-198 in 62 patients) with or without external radiation. 56 other patients received external irradiation alone and another 14 patients received pre-operative external irradiation plus surgery. 2-year recurrence-free rates were 73% (100% for T1, 76% for T2, 36% for T3 tumours) in the patients who received interstitial implant with or without external radiation and 36% (67% for T1, 48% for T2, 13% for T3 tumours) in the patients treated by external irradiation alone. The incidence of soft-tissue or bone complications requiring long-term treatment was 14%. Based on these findings, it is believed that an interstitial implant using Au-198 grains combined with external beam irradiation is a useful treatment modality for small lesions of the oropharynx.

Squamous cell carcinoma of the oral cavity: MR findings and value of T1-versus T2-weighted fast spin-echo images

OBJECTIVE

The purposes of this study were to describe the characteristics of squamous cell carcinomas of the oral cavity on unenhanced and contrast-enhanced T1-weighted spin-echo (SE) MR images and unenhanced T2-weighted fast spin-echo (FSE) MR images and to determine which sequences best delineate the margins and extent of the tumors.

MATERIALS AND METHODS

Forty-four patients with proved squamous cell carcinoma of the oral cavity (tongue, 24; floor of mouth, seven; buccal mucosa, four; maxillary gingiva, two; and mandibular gingiva, seven) underwent unenhanced axial T2-weighted FSE MR imaging and unenhanced and enhanced axial and coronal T1-weighted SE MR imaging. The appearance, signal characteristics, and extent of the tumors were assessed, and the delineation of tumor margins with each sequence or combination of sequences was evaluated by use of a grading system ranging from 1 (poor) to 3 (excellent). Three patients were excluded because of artifacts on the MR images caused by dental restorations.

RESULTS

Tumors in all 41 patients were depicted on unenhanced T1-weighted SE images, but in four patients, tumors were not visible on T2-weighted FSE images. Except for tumors that invaded the maxillary gingiva, the tumors generally had homogeneous, low signal intensity on unenhanced T1-weighted images and nonhomogeneous, high signal intensity on T2-weighted FSE images. All tumors showed enhancement, 76% with a nonhomogeneous appearance. The delineation of tumor margins was excellent (grade 3) in 31 cases and fair (grade 2) in 10 cases. The highest rating was given for unenhanced T1-weighted images in 10 cases, for contrast-enhanced T1-weighted images in 10 cases, for the combination of both unenhanced and contrast-enhanced T1-weighted images in 18 cases, for the combination of unenhanced T1-weighted and T2-weighted FSE images in five cases, and for T2-weighted FSE images in one case. In three cases, the highest rating was given for both combinations of pulse sequences.

CONCLUSION

An unenhanced T1-weighted sequence should be used as the basic pulse sequence for MR imaging of tumors of the oral cavity. When tumor margins are not clearly delineated with this sequence, T2-weighted FSE and contrast-enhanced T1-weighted sequences should be added. Although both of these sequences provide supplementary information, the contrast-enhanced T1-weighted sequence is more useful in delineating the margins and extent of tumors than is the T2-weighted FSE sequence.

Effects of midazolam and flumazenil on carotid sinus baroreflex control of circulation in rabbits

We have studied the effects of midazolam and flumazenil on the carotid sinus baroreflex, by examining mean arterial pressure (MAP) and heart rate (HR) responses to partial or complete bilateral carotid occlusion (BCO) in 12 conscious rabbits after aortic denervation. In eight rabbits, the responses to complete BCO were evaluated before and after cumulative doses of midazolam 0.5 and 1.0 mg kg-1, and after flumazenil 0.3 mg kg-1 following administration of midazolam. Midazolam and flumazenil had no effect on MAP or HR before complete BCO and neither affected the MAP response to complete BCO. Midazolam 0.5 and 1.0 mg kg-1 decreased the HR response to 60% and 58% of control, respectively. Flumazenil restored the midazolam-induced depression of the HR response to the control level. In the other four rabbits, we examined the MAP and HR responses to partial BCO (carotid artery pressure reduced by 5, 10 and 20 mm Hg) before and after midazolam 0.5 mg kg-1 and after flumazenil 0.3 mg kg-1 following administration of midazolam. The response to partial occlusion showed the same tendency as the response to complete BCO. These results indicate that midazolam attenuated the HR response of the carotid sinus baroreflex, flumazenil restored this midazolam-induced depression and neither drug affected the MAP response.