A multicenter randomized phase II study of full-dose gemcitabine and concurrent radiotherapy comparing gemcitabine alone for the unresectable locally advanced pancreatic adenocarcinoma

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Background: Some of locally advanced pancreatic cancers (LAPC) are considered to include a potential micro metastasis. We think that full-dose of gemcitabine (GEM) improve the outcome of LAPC. We report the efficacy of full-dose GEM and concurrent radiotherapy, comparing GEM alone for unresectable LAPC. Methods: Patients with histologically or cytologically proven pancreatic adenocarcinoma were eligible for this study. We decide that LAPA which involved a major artery with CT imaging was unresectable. Patients were randomized into a concurrent chemoradiotherapy (CRT) group and a chemotherapy alone (CTX) group. GEM was given intravenously at a dose of 1,000 mg/msq over 30 min on days 1, 8 and 15 of each 28-day cycle and repeated until disease progression in both groups. Patients randomized into CRT group received a limited field irradiation with a total dose of 50 Gy in 25 sessions during first two cycles. The two groups were compared for mean survival, progression free survival and safety. Results: From September 2002 to April 2005, 80 patients were randomized at two institutions into the two arms of the trial (40 patients to CRT group and 40 patients to CTX group). The CRT group had better results than the CTX group as measured by mean survival time (391 vs 372 days, P< 0.02) and progression free survival (237 vs 128 days, P< 0.01). There were no differences in the safety between both groups. Conclusions: The concurrent chemoradiotherapy with full-dose GEM is effective and feasible in patients of LAPC compared with full-dose GEM alone.

No significant financial relationships to disclose.

Trilateral optical powermeter comparison between NIST, NMIJ/AIST, and METAS

We describe the results of a comparison of reference standards between three National Metrology Institutes: the National Institute of Standards and Technology (NIST, USA), the National Metrology Institute of Japan/National Institute of Advanced Industrial Science and Technology (NMIJ/AIST, Japan), and the Federal Office of Metrology (METAS, Switzerland). Open-beam- (free field) and optical-fiber-based measurements at wavelengths of 1302 and 1546 nm are reported. Three laboratories' reference standards are compared by means of two temperature-controlled, optical trap detectors. Measurement results show the largest differences of less than 4.2 parts in 10(3), which is within the expanded (k=2) uncertainty for the laboratories' reference standards.

Inactivation of Cryptosporidium parvum by ultrasonic irradiation

The inactivation of Cryptosporidium parvum was investigated by the use of three different sonicators utilizing the squeeze-film effect, which may occur when ultrasound is irradiated into an extremely thin space and generate intensified pressure in the sample suspension. To expand from the small-scale horn-type sonicator to large-scale cylindrical or cleaning bath sonicators, the inactivation effectwas improved. In the case of the cylindrical sonicator (26.6 kHz, 30 W), 97% of the initial concentration of 2260 oocysts mL(-1) was inactivated at33 mL min(-1) (residence time of approximately 5.2 min). Hundreds of cubic meters of water can be treated per day at several kW using this sonicator. In addition, the simultaneous use of sonication and chlorination showed a beneficial effect on inactivation for C. parvum based on the evaluation of infectivity testing and morphological observation.

[Aortic valve replacement presence of anti-Jr(a) antibody]

A 65-year-old female with a heart murmur developed progressive symptom of chest oppression. She was diagnosed severe aortic valve stenosis with echocardiogram. Antibody screening revealed anti-Jr(a) antibody. Preoperatively, erythropoietin was administered. Over 14 days, a total 1,000 ml of her blood was drawn and stored for autologous transfusion. The aortic valve was replaced with ATS mechanical valve [18 mm advanced performance (AP)]. Following surgery, her stored blood was administered to him. But her HCT was 17% on the 1st postoperative day. Frozen thawed red cells were transferred 7th postoperative day.

Treatment of gastric hemorrhage by pulverized omeprazole and antacid – concomitant administration via a nasogastric tube

Gastroesophageal reflux (GER) is a common episode in pediatric patients with severe motor and intellectual disabilities (SMID) and occasionally leads to a severe clinical state accompanied with nausea, hematemesis, melena, wheezing, pneumonia, anemia and/or failure to thrive. We report here a case of a 14-year-old male with Lennox syndrome who had been treated with a histamine H2 blocker intravenously or via a nasogastric tube for repeated gastric hemorrhage due to severe GER. Since his gastric hemorrhage became resistant to the H2 blocker, we decided to replace it with a proton pump inhibitor (PPI). Although lansoprazole can be decapsulated for administration via a nasogastric tube, it tends to block fine tubes. The acid-sensitive drug omeprazole, another oral PPI, is commercially available as enteric-coated tablets. Therefore, we pulverized the tablets and administered omeprazole, mixed with a small amount of antacid, via a nasogastric tube. The patient's gastric hemorrhage was dramatically improved. Thus, administration of pulverized omeprazole concomitantly with antacid via a fine nasogastric tube may provide a novel approach for the treatment of chronic GER in pediatric patients with SMID.

[Surgical treatment for left ventricular false aneurysm caused by infective endocarditis; report of a case]

A 24-year-old man who had left ventricular (LV) false aneurysm, which is caused by mitral valve infective endocarditis, underwent aneurysmectomy, direct closure of aneurysmal mouth and concomitant mitral valve replacement. Post-operative course was uneventful. It has been reported that the etiology of this false aneurysm was due to the vegetations' friction, which could have caused an initial endocardial ulceration that progressively expanded into the myocardium. The false aneurysmal wall should be completely removed in order to eliminate the possibility of recurrence of the infective endocarditis. We believe that the surgical treatment should be carried out as soon as possible after completion of diagnosis because the aneurysmal wall is usually quite thin and could rupture easily.

Simultaneous stimulation of EP2 and EP4 is essential to the effect of prostaglandin E2 in chondrocyte differentiation

OBJECTIVE

Prostaglandin E(2)(PGE(2)) has been reported to stimulate chondrocyte differentiation. However, the precise actions and signal transduction pathways of PGE(2)in cartilage are largely unknown. Our purpose is to identify which of the four PGE(2)receptor subtype(s), EP1-4, mediates the action of PGE(2)on chondrocyte differentiation.

DESIGN

We used primary chondrocytes derived from the resting zone of rat rib cartilage. The effects on chondrocyte differentiation were assessed by measuring the Alcian blue-stainable proteoglycan content and the expression levels of type II collagen mRNA by Northern blot analysis. The expression of the four PGE(2)receptor subtypes in rat primary chondrocytes was examined by reverse transcription-polymerase chain reaction.

RESULTS

PGE(2)stimulated the accumulation of proteoglycan and up-regulated the expression of type II collagen mRNA in primary chondrocytes. Dibutyryl cAMP, a cell-permeable analog of cAMP, an important intracellular mediator of PGE(2)signaling, also enhanced the expression of type II collagen mRNA and proteoglycan accumulation in chondrocytes. No EP agonist alone induced the expression of type II collagen mRNA. However, simultaneous administration of EP2 and EP4 agonists at high concentrations cooperatively induced the expression of type II collagen mRNA, mimicking the PGE(2)effect. The simultaneous stimulation of EP2 and EP4 also cooperatively enhanced proteoglycan accumulation and intracellular cAMP production. Moreover, an EP4 antagonist partially blocked the stimulatory actions of PGE(2)on the expression of type II collagen mRNA.

CONCLUSION

These results suggest that simultaneous stimulation of EP2 and EP4 is necessary and sufficient to elicit the effect of PGE(2)on rat primary chondrocyte differentiation.

[Prosthetic valve endocarditis after aortic valve replacement with freestyle stentless xenograft]

A 52-year-old man underwent aortic valve replacement with freestyle stentless xenograft, using subcoronary technique for active infective endocarditis in June, 2001. Eighteen month later he had late prosthetic valve endocarditis associated with aortic annular abscess due to Staphylococcus epidermidis infection. The abscess was debrided and gelatin-resorcin-formalin glue (GRF glue) was injected into the abscess cavity. Abscess cavity was closed with continuous running suture of 3-0 polypropylene stitches. Finally the aortic valve was replaced with ATS mechanical valve (20 mmAP). After administration of vancomycin and gentamicin for 4 weeks, he discharged on 57th postoperative day in good condition. We strongly suggest that GRF glue is essential to close the aortic annular abscess of combined with aortic regurgitation due to active infective endocarditis.

[Thymic carcinoma (mixed small cell undifferentiated squamous cell carcinoma); report of a case]

A 52-year-old man was admitted to our hospital on October, 1997 with complains of left anterior chest pain. A chest X-ray and computed tomography on admission showed evidence of a mass in the left anterior mediastinum. The patient was treated with combination chemotherapy [cisplatin (CDDP), etoposide (VP-16)] and radiation therapy (2 gray x 25 days), preoperatively. Median sternotomy revealed a tumor invading into the left anterior chest wall, the pericardium, and partial pleura. The tumor was extirpated with combined resection of invaded organs. Microscopically and immunohistochemically, the tumor was diagnosed mixed small cell and undifferentiated squamous cell carcinoma documented by Snover et al. The patient was discharge on March 1998, but 2 years later after operation, he was dead by recurrent. We reported a rare case of thymic carcinoma.

Postural response of low-frequency component of heart rate variability is an increased risk for mortality in patients with coronary artery disease

STUDY OBJECTIVES

We examined whether autonomic functions assessed by heart rate variability (HRV) during standardized head-up tilt testing (HUTT) predict risk for death in stable patients with coronary artery disease (CAD).

DESIGN AND SETTING

Retrospective cohort study in medium-sized university general hospital.

MEASUREMENTS AND RESULTS

In a cohort of 250 patients with CAD who were undergoing elective coronary angiography, we analyzed HRV during standardized HUTT under paced breathing with discontinuation of treatment with all medications. During a subsequent mean follow-up period of 99 months, there were 13 cardiac deaths and 12 noncardiac deaths. Cox regression analysis adjusted for cardiovascular risks revealed that increased postural change (supine to upright) in the power of low-frequency component (LF) power predicted an increased risk for cardiac death (relative risk [per 1-ln ms(2) increment], 4.36; 95% confidence interval, 1.64 to 11.6), while neither the high-frequency component nor its response to HUTT predicted any form of death. When the patients were trichotomized by the level of postural LF change (large drop, < or = - 0.6 ln[ms(2)]; small drop and rise, > 0 ln[ms(2)]), the three groups did not differ in terms of clinical features or CAD severity at baseline or coronary interventions during the follow-up period; however, the 8-year cardiac mortality rates were 0%, 6%, and 12%, respectively (p = 0.008 [log rank test]). Additionally, the difference was enhanced when analyzed excluding 64 patients who had been treated with a beta-blocker during the follow-up period (0%, 7%, and 15%, respectively; p = 0.006 [log rank test]).

CONCLUSIONS

The postural response of HRV predicts the risk for death in patients with CAD. Postural LF increase (LF rise), in particular, is an independent risk factor for cardiac death.

The role of E-cadherin in the differentiation of gallbladder cancer cells

Cell adhesion molecules are essential for development and maintenance of epithelial architecture. To clarify the role of these molecules in the morphology of gallbladder cancers, four human gallbladder cancer cell lines (GB-d1, KMG-C, GBK-1, and G-415) were examined in vitro. They showed noticeably different morphologies in our standard gel cultures (SC). GB-dl and KMG-C formed cystic and spheroid structures, respectively, which seemed to represent well-differentiated and moderately differentiated cancers, respectively. GBK-1 and G-415 showed branching and "pseudoglandular" structures, respectively, both of which seemed to indicate original dedifferentiated cancers. In floating gel culture (FC), only GB-d1 showed a highly increased tendency toward cyst formation. Expression of E-cadherin and alpha-catenin in the gallbladder cancer cell lines was investigated by Western-blotting analysis. Expression was detected in GB-d1 and KMG-C, but not in GBK-1 and G-415 cells. Furthermore, E-cadherin expression in GB-dl was 1.82 times greater in FC than in SC, while E-cadherin expression levels of KMG-C did not change. Neither GB-d1 nor KMG-C showed any difference in a-catenin expression between SC and FC. Immunostaining of GB-d1 revealed that these proteins were localized to the cell membrane. In contrast, heterogeneous localization of these proteins was detected in the spheroid structures of KMG-C, in both SC and FC. Electronmicroscopic examination revealed that reestablishment of the junctional complex occurred only in GB-d1 cells cultured in FC. The formation of cystic structures in GB-d1 was completely inhibited by an antibody against human E-cadherin. Both expression of E-cadherin and its membranous localization are required for well-differentiated-type morphogenesis in gallbladder cancer cells.

Predicting cerebral blood flow response to orthostatic stress from resting dynamics: effects of healthy aging

The transfer function relating arterial pressure (AP) to cerebral blood flow velocity (CBFV) during resting conditions has been used to predict the CBFV response to hypotension. We hypothesized that this approach could predict the CBFV response to posture change in elderly individuals if impaired autoregulation allowed changes in AP to be passively transferred to CBFV. AP (Finapres) and CBFV (middle cerebral artery transcranial Doppler) were measured in 10 healthy young (age 24 +/- 1 yr) and 10 healthy elderly (age 72 +/- 3 yr) subjects during 5 min of quiet sitting and 1 min of active standing while breathing was paced at 0.25 Hz. Transfer functions between AP and CBFV changes during sitting were estimated from each full waveform in both low-frequency (LF; 0.05-0.2 Hz) and heartbeat-frequency (HBF; 0.7-1.4 Hz) ranges. The impulse-response function was used to compute changes in CBFV during posture change. The LF transfer function did not predict orthostatic changes in CBFV in either group, suggesting normal cerebral autoregulation. In the HBF range, the prediction was high in elderly (R = 0.65 +/- 0.23) but not young subjects (R = 0.19 +/- 0.35; P < 0.003, young vs. elderly). Thus rapidly acting regulatory mechanisms that reduce the transmission of beat-to-beat changes in AP to CBFV may be engaged during posture change in young but not elderly subjects.

Prevention and detection of spinal cord injury during thoracic and thoracoabdominal aortic repairs

BACKGROUND

Spinal cord injury is a most dreaded and unpredictable complication. In this study, based on our experimental results in dogs and early clinical results, we reviewed the incidence of paraplegia and the detection of spinal cord injury.

METHODS

Eighty-two patients who underwent elective surgical repair of the descending thoracic and thoracoabdominal aorta over 17 years were subjects for this study. Sixty-two patients were male and 20 were female. Their mean age was 61.6 years (range, 17 to 81 years). Monitoring somatosensory evoked potentials (SEP) and measurement of mean distal aortic pressure and cerebrospinal fluid pressure were performed perioperatively.

RESULTS

Sixty patients had no ischemic change in SEP. In 17 patients with significant ischemic changes of SEP, SEP recovered by increasing spinal cord perfusion pressure to more than 40 mm Hg. Two patients with complete loss of SEP experienced paraplegia. One patient had delayed paraplegia.

CONCLUSIONS

These results strongly suggest that SEP, mean distal aortic pressure, cerebrospinal fluid pressure should be monitored during aortic cross-clamping. Maintaining spinal cord perfusion pressure at more than 40 mm Hg by increasing mean distal aortic pressure or withdrawal of cerebrospinal fluid is valuable for preventing paraplegia.

A case of bladder pheochromocytoma

The clinical picture of bladder pheochromocytoma is usually typical; however, the diagnosis is occasionally delayed because of the rarity of this neoplasm. We report a case of unsuspected bladder pheochromocytoma in which the patient had a hypertensive episode during transurethral resection. A 67-year-old male presented with the chief complaint of painless macrohematuria. Cystoscopy revealed a submucosal tumor on the right lateral wall of the bladder. The tumor was operated on transurethrally, followed by partial cystectomy. The pathological diagnosis was pheochromocytoma, primarily occurring in the bladder. Treatment of this lesion requires a high degree of clinical suspicion based on the patient's symptom complex in order to enable adequate preparation prior to surgical manipulation.

Impact of coronary artery remodeling on clinical presentation of coronary artery disease: an intravascular ultrasound study

OBJECTIVES

We examined the association between the features of the culprit lesion in coronary artery disease (CAD) and clinical presentation as shown by intravascular ultrasound (IVUS).

BACKGROUND

The association between coronary remodeling pattern and clinical presentation of CAD is unclear.

METHODS

We analyzed 125 selected patients who underwent preintervention IVUS. Acute myocardial infarction (AMI) and unstable angina pectoris (UAP) were categorized as an acute coronary syndrome (ACS), and stable angina pectoris (SAP) and old myocardial infarction (OMI) as stable CAD. Coronary remodeling patterns and plaque morphology of the culprit lesion obtained by IVUS were analyzed in terms of their association with clinical presentation or angiographic morphology.

RESULTS

Angiographically complex lesions were associated with ACS and OMI. In patients with a complex lesion, positive remodeling was observed more frequently than in those with a simple lesion. In AMI and UAP, positive remodeling was observed more frequently than in SAP and OMI (82% vs. 78% vs. 33% vs. 40%, respectively, p < 0.0001). The remodeling ratio was greater in AMI and UAP than in SAP and OMI (1.26 +/- 0.15 vs. 1.11 +/- 0.10 vs. 0.94 +/- 0.11 vs. 0.96 +/- 0.13, respectively, p < 0.0001). Furthermore, within ACS, the remodeling ratio was greater in AMI than in UAP (1.26 +/- 0.15 vs. 1.11 +/- 0.10, respectively, p < 0.05), whereas the frequency of positive remodeling was not different.

CONCLUSIONS

Positive remodeling was more frequently observed in ACS than in stable CAD. Moreover, the degree of positive remodeling was greater in AMI than in UAP. These results may reflect the impact of remodeling types and its degree in the culprit lesion of CAD on clinical presentation.

T cell-mediated tumor rejection displays diverse dependence upon perforin and IFN-gamma mechanisms that cannot be predicted from in vitro T cell characteristics

Experimental pulmonary metastases have been successfully treated by adoptive transfer of tumor-sensitized T cells from perforin knockout (KO) or Fas/APO-1 ligand(KO) mice, suggesting a prominent role for secretion of cytokines such as IFN-gamma. In the present study we confirmed that rejection of established methylcholanthrene-205 (MCA-205) pulmonary metastases displayed a requirement for T cell IFN-gamma expression. However, this requirement could be obviated by transferring larger numbers of tumor-sensitized IFN-gamma (KO) T cells or by immunosensitizing sublethal irradiation (500 rad) of the host before adoptive therapy. Extrapulmonary tumors (MCA-205 s.c. and intracranial) that required adjunct sublethal irradiation for treatment efficacy also displayed no requirement for host or T cell expression of IFN-gamma. Nonetheless, rejection of MCA-205 s.c. tumors and i.p. EL-4 tumors, but not MCA-205 pulmonary or intracranial tumors, displayed a significant requirement for T cell perforin expression (i.e., CTL participation). The capacity of T cells to lyse tumor targets and secrete IFN-gamma in vitro before adoptive transfer was nonpredictive of the roles of these activities in subsequent tumor rejection. Adoptive therapy studies employing KO mice are therefore indispensable for revealing a diversity of tumor rejection mechanisms that may lack in vitro correlation due to delays in their induction. Seemingly contradictory KO data from different studies are reconciled by the capacity of anti-tumor T cells to rely on alternative mechanisms when treated in larger numbers, the variable participation of CTL at different anatomic locations of tumor, and the apparent capacity of sublethal irradiation to provide a therapeutic alternative to host or T cell IFN-gamma production.

Reliable and cost-effective system for surgical stent graft insertion

For intraoperative stented graft implantation, we use a half-inch translucent soft polyvinyl tube as a sheath and an obturator from a two-stage venous cannula as a pushing rod. Ten centimeters of any kind of graft can be used for the stent graft itself. The stent we used was a self-expandable Gianturco double Z stent and was sutured inside the graft.

Cross-presentation of tumor antigens to effector T cells is sufficient to mediate effective immunotherapy of established intracranial tumors

The systemic adoptive transfer of tumor-sensitized T cells, activated ex vivo, can eliminate established intracranial tumors. Regression of MHC class II negative MCA 205 fibrosarcomas occurs optimally following adoptive transfer of both CD4 and CD8 tumor-sensitized T cells, indicating an important function for tumor-infiltrating APC. Here, we demonstrate that during an effector response, indirect presentation of tumor Ags to transferred T cells is sufficient to mediate intracranial tumor regression. BALB/c --> CB6F1 (H-2bxd) bone marrow chimeras were challenged with the MCA 205 fibrosarcoma (H-2b). The tumor grew progressively in the H-2b-tolerant chimeras and stimulated an immune response in tumor-draining lymph nodes. Tumor-sensitized lymph node T cells were activated ex vivo with anti-CD3 and IL-2, then adoptively transferred to sublethally irradiated BALB/c or C57BL/6 recipients bearing established intracranial MCA 205 tumors. The transferred T cells eradicated MCA 205 tumors in BALB/c recipients and demonstrated tumor specificity, but had no therapeutic efficacy in the C57BL/6 recipients. These data establish that tumor-associated host cell constituents provide sufficient Ag presentation to drive effector T cell function in the complete absence of direct tumor recognition. This effector mechanism has an evident capacity to remain operative in circumstances of immune escape, where the tumor does not express the relevant MHC molecules, and may have importance even at times when direct CTL recognition also remains operative.

Meloxicam inhibits the growth of non-small cell lung cancer

Cyclooxygenase (COX)-2 has been reported to play an important role in carcinogenesis. Meloxicam (preferential COX-2 inhibitor) inhibits the growth of COX-2 positive and COX-1 negative colorectal cancer cells. We evaluated the effects of meloxicam on the growth of lung cancer cells. By reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis, COX-2 but not COX-1 was expressed in human non-small cell lung cancer (NSCLC) cell lines (A549 and PC14). In human small cell lung cancer (SCLC) cell line (H841), both COX-1 and COX-2 were not detected. MTT assay and prostaglandin (PG) E2 enzyme immunoassay showed that meloxicam inhibited the growth and PGE2 production of both A549 and PC14, but not H841 cells. These findings suggest that COX-2 may play an important role in the pathogenesis and progression of NSCLC, and that meloxicam may be a useful therapeutic agents in the treatment of NSCLC.

Early characteristic findings in bowleg deformities: evaluation using magnetic resonance imaging

We used magnetic resonance imaging (MRI) to evaluate bowleg deformities in infancy. Twenty-five tibiae of 13 infants were examined and divided into two groups based on MRI findings: group A had high intensity area in the medial epiphyseal cartilage on T2-weighted images. Group B had depression of medial physis and abnormal signal in the perichondrial region in addition to the epiphyseal lesion. At the final follow-up, all cases in group A demonstrated normal lower leg alignments, whereas five cases in group B showed characteristic roentogenographic findings of Blount's disease. The improvement rate of metaphyseal-diaphyseal angle was correlated with this classification. These findings suggested that abnormal findings in physis and perichondrial region might be preliminary findings in early stage of Blount's disease. The high intensity areas in the medial epiphyseal cartilage were commonly found among the cases with bowing deformities, which suggested that there might be a common pathomechanism between physiologic bowing and infantile Blount's disease.

2-5A antisense telomerase RNA therapy for intracranial malignant gliomas

Malignant gliomas are the most common intracranial tumors and are considered incurable. Therefore, exploration of novel therapeutic modalities is essential. Telomerase is a ribonucleoprotein enzyme that is detected in the vast majority of malignant gliomas but not in normal brain tissues. We, therefore, hypothesized that telomerase inhibition could be a very promising approach for the targeted therapy of malignant gliomas. Thus, 2-5A (5'-phosphorylated 2'-5'-linked oligoadenylate)-linked antisense against human telomerase RNA component (2-5A-anti-hTER) was investigated for its antitumor effect on an intracranial malignant glioma model. 2-5A is a mediator of one pathway of IFN actions by activating RNase L, resulting in RNA degradation. By linking 2-5A to antisense, RNase L degrades the targeted RNA specifically and effectively. Prior to the experiments using intracranial tumor models in nude mice, we modified the in vitro and in vivo treatment modality of 2-5A-anti-hTER using a cationic liposome to enhance the effect of 2-5A-anti-hTER. Here we demonstrate that 2-5A-anti-hTER complexed with a cationic liposome reduced the viability of five malignant glioma cell lines to 20-43% within 4 days but did not influence the viability of cultured astrocytes lacking telomerase. Furthermore, treatment of intracranial malignant gliomas in nude mice with 2-5A-anti-hTER was therapeutically effective compared with the control (P < 0.01). These findings clearly suggest the therapeutic potentiality of 2-5A-anti-hTER as a novel approach for the treatment of intracranial malignant gliomas.

Dynamic regulation of middle cerebral artery blood flow velocity in aging and hypertension

BACKGROUND AND PURPOSE

Although aging and hypertension may predispose hypertensive elderly subjects to cerebral hypoperfusion during orthostatic stress, their effects on the acute cerebral autoregulatory response to hypotension are not known.

METHODS

Continuous middle cerebral artery blood flow velocity (BFV) (transcranial Doppler ultrasound) and mean arterial pressure (MAP, Finapres) were measured in response to (1) acute hypotension during standing, (2) steady-state sitting and standing, and (3) hypercarbia during CO(2) rebreathing in 10 healthy young subjects (age 24+/-1 years), 10 healthy elderly subjects (age 72+/-3 years), and 10 previously treated hypertensive elderly (age 72+/-2 years) subjects. CO(2) reactivity was computed as the slope of cerebrovascular conductance (CVC=BFV/MAP) versus end-expiratory CO(2). Coherence, transfer magnitudes, and phases between low-frequency MAP and BFV signals were computed from their autospectra during 5 minutes of sitting and standing.

RESULTS

MAP fell to a similar extent in all groups by an average of 21 to 26 mm Hg (22% to 26%) within 30 seconds of standing. Mean BFV also fell in all subjects but significantly less in the older subjects (-4.7+/-0. 7 cm/s in hypertensives and -5.3+/-1.2 cm/s in normotensives, P=NS) compared with younger subjects (-10.1+/-1.1 cm/s, P<0.05). CO(2) reactivity was greater in the young subjects (0.19+/-0.01) compared with normotensive (0.14+/-0.01, P<0.05) and hypertensive elderly subjects (0.11+/-0.02, P<0.05) (P=NS between elderly groups). Fewer hypertensive subjects had coherence between MAP and BFV signals; for subjects with coherence, there were no significant group differences in phase or transfer magnitudes in either sitting or standing positions.

CONCLUSIONS

Despite reduced CO(2) reactivity, elderly normotensive and previously treated hypertensive subjects retain cerebral autoregulatory capacity in response to acute orthostatic hypotension.