Adaptive correction of imaging plane position in segmented k-space cine cardiac MRI

Variability among breath-holds frequently produces registration errors, a situation that may contribute to reproducibility error in anatomic indices. A navigator-echo-based method for real-time prospective correction of imaging slice level was applied to breath-hold cine cardiac imaging of 13 subjects. Repeat acquisitions with correction in the cardiac short-axis orientation showed significantly improved reproducibility in fractional area change and endocardial centroid location as compared with conventional noncorrected methods.

Streptococcus adjacens endocarditis in a patient with nephrotic syndrome

Streptococcus adjacens has never previously been reported as an etiologic organism of infective endocarditis in Taiwan. We describe a case of severe native valve endocarditis caused by S. adjacens, involving the mitral valve, the aortic valve, and the left atrium, in a 29-year-old woman with nephrotic syndrome on steroid therapy. Blood cultures yielded gram-positive cocci that grew poorly on blood agar but strongly on chocolate agar. Despite aggressive antibiotic treatment, the patients continued to have high fever and progressive congestive heart failure, which necessitated surgical intervention. Symptoms were alleviated after surgery; teicoplanin was continued for 4 weeks and the patient remained symptom-free at the 6 month follow up. To our knowledge, this is the first reported case of bacterial endocarditis involving the left atrium without preexisting myxoma.

Roles of N-glycans with alpha2,6 as well as alpha2,3 linked sialic acid in infection by polyoma virus

Specific glycosylation inhibitors were used to show that N-glycans, and not O-glycans or glycolipids, constitute the major class of receptors on 3T3 cells for polyoma virus. Sialic acid (SA)-specific lectins were used in attempts to confirm the expected SA linkage on N-linked glycans. A lectin specific for alpha2,6 linked SA, a non-receptor type, was slightly more effective in blocking infection than a lectin specific for alpha2,3 linked SA which corresponds to the known receptor specificity. Possible explanations are suggested for this unexpected result.

Predictive variable selection for the multivariate linear model

We develop a predictive Bayesian approach to variable selection in the multivariate linear model. A criterion derived from the Bayesian predictive density is proposed and a calibration is provided for it. Reference and informative priors are discussed, and an automated method that focuses on the response variable is proposed for specifying informative priors for the regression parameters. Relationships between the proposed criterion and other several well-known criteria are examined. Illustrative examples involving real data are given to demonstrate the methodology.

In vivo angioplasty prevents the development of vasospasm in canine carotid arteries. Pharmacological and morphological analyses

BACKGROUND AND PURPOSE

To study the effects of in vivo transluminal balloon angioplasty (TBA) on the structure and function of the arterial wall, a canine model of hemorrhagic cerebral vasospasm of the high cervical internal carotid artery (ICA) was used. This model was also used to determine whether TBA performed before clot placement could prevent the development of vasospasm.

METHODS

Twelve dogs underwent surgical exposure of both distal-cervical ICAs, followed by baseline angiography. One randomly selected ICA in each dog was then subjected to in vivo TBA and repeated angiography. Both distal ICAs were then surrounded with blood clots held by silicone elastomer sheaths. Seven days later angiography was repeated, and all animals were killed. The ICAs in four animals were perfusion-fixed in situ for morphological analysis by electron microscopy, and the arteries in the remaining eight animals were removed and immediately immersed in oxygenated Krebs' solution. Contractile responses of isolated arterial rings from each ICA were recorded after treatment with KCl, noradrenaline, serotonin, and prostaglandin F2 alpha, while relaxations in response to the calcium ionophore A23187 and papaverine were recorded after tonic contraction to noradrenaline had been established. The morphology and pharmacological responses of ICAs that had been exposed to blood with or without prior TBA were compared with data obtained from control arterial segments of intact, more proximal regions of the ICAs from each animal.

RESULTS

TBA resulted in immediate angiographic enlargement of the ICA lumen that was still evident 7 days later despite the placement of clotted blood around the artery. Scanning and transmission electron microscopy demonstrated flattening of the intima and internal elastic lamina in these dilated arteries, associated with patchy losses of endothelial cells. In contrast, ICAs that had been exposed to clotted blood but had not undergone prior TBA developed consistent angiographic and morphological vasospasm. In comparison with control vessels and nondilated vasospastic vessels, vessels dilated with TBA and then exposed to clotted blood showed significantly diminished responses to all compounds tested, with the exception of prostaglandin F2 alpha.

CONCLUSIONS

These results indicate that in vivo TBA results in a degree of functional impairment of vascular smooth muscle that persists for at least 7 days. This result is consistent with previous observations of the acute effects of TBA in isolated arteries. Furthermore, these results support the hypothesis that normal smooth muscle function is required for the development of vasospasm. Finally, these results indicate that TBA performed before the onset of vasospasm prevents its development.

Real-time ultrasonography of the pancreas in normal Chinese children in Taiwan

The real-time ultrasound images of the pancreas in 142 children without clinical or laboratory evidence of pancreatic disease prospectively were analyzed to determine normal pancreatic size in Chinese children in Taiwan. Sonographic examinations of the pancreas were performed by sagittal scanning at the epigastrium; the long axis and short axis of the oval cross-sections of both the pancreatic head and body were measured. The relationships between pancreatic dimensions and body height, body weight, surface area and age were evaluated with linear regression analysis. Correlations with body height and age were better than those obtained with body surface area and body weight. Since all the physical parameters had better correlations with the long, rather than the short, axis of the pancreas, this indicated that the growth of the pancreas in children is primarily in the craniocaudal direction rather than the anteroposterior direction.

Comparison of respiratory suppression methods and navigator locations for MR coronary angiography

OBJECTIVE

Currently, breath-holding during MR coronary angiography is used to minimize respiratory motion. This technique requires patient cooperation and is associated with slice registration errors. The goal of this study was to evaluate alternative non-breath-hold techniques for MR coronary angiography during free breathing.

SUBJECTS AND METHODS

Subjects underwent MR coronary angiography using an ECG-gated, fat-suppressed, segmented K-space, gradient-echo sequence. Images were obtained during free breathing using both real-time navigator gating and respiratory bellows gating. These were compared with images obtained during conventional breath-holding. The optimal navigator location (diaphragmatic or cardiac) was also studied. Image quality, registration error, and scan time were measured for all scans.

RESULTS

Navigator gating for MR coronary angiography during free breathing resulted in image quality equivalent to that obtained during breath-holding and was superior to that obtained with respiratory bellows gating (p < .04). Also, navigator gating reduced registration errors by 75% compared with breath-holding (p < .01) and did not increase scan time. No significant differences in the parameters measured were observed among the different navigator locations.

CONCLUSION

Real-time navigator gating for MR coronary angiography during free breathing achieved image quality and scan time equivalent to breath-holding. Navigator gating also significantly reduced registration error. Compared with breath-holding and respiratory bellows gating, navigator gating during free breathing is a more optimal approach for suppression of respiratory motion during MR coronary angiography.

Echocardiographic assessment of mitral stenosis and its associated valvular lesions in 205 patients and lack of association with mitral valve prolapse

To date, the relation between mitral stenosis (MS) and other associated cardiac valvular lesions has been reported by angiography and surgical pathologic study in patients with more advanced disease but has not been studied systematically by two-dimensional echocardiography and Doppler color flow mapping in a large referral population with a broader spectrum of severity. In addition, prior reports have suggested that up to 40% of patients with MS have mitral valve prolapse (MVP); however, because of recent developments in two-dimensional echocardiographic imaging and the definition of MVP, this association must now be reconsidered. The purpose of this study was to explore the association of other valvular lesions with MS and their relation to its severity and in particular to test whether MS is in fact associated with MVP with the frequency reported previously. We reviewed the studies of 205 consecutive patients (aged 61 +/- 14 years; range 26 to 87 years) with MS who were studied from 1992 to 1994 by two-dimensional echocardiography and Doppler color flow mapping to assess valvular stenosis, regurgitation, and MVP in patients with a range of severity of MS (28% mild, 34% moderate, and 38% severe MS based on mitral valve area). MS was associated with at least mild mitral regurgitation in 78% of patients (160/205), and pure MS was correspondingly uncommon (22%). There was an inverse relationship between the severity of MS and the degree of mitral regurgitation (p < 0.001). MS was frequently associated (54% of patients) with significant lesions of other valves, including aortic stenosis (17%), at least moderate aortic regurgitation (8%) and tricuspid regurgitation (38%), and tricuspid stenosis (4%). Tricuspid stenosis was associated with more severe MS (p < 0.01), and tricuspid regurgitation was more common in patients with mixed MS and regurgitation than in those with pure stenosis (60% versus 26% for at least moderate tricuspid regurgitation; p < 0.001). Mitral valve prolapse was present in only one patient (0.5%). Superior systolic bulging of the midportion of the anterior mitral leaflet toward the left atrium (but not superior to the annular hinge points) was seen in 22 patients (11%). Patients with such superior bulging had significantly lower mitral valve scores but a similar degree of mitral regurgitation compared with those without bulging. The majority of patients with MS (78%) have associated mitral regurgitation and significant lesions of the other cardiac valves (54%). The frequency of true MVP associated with chronic MS is much lower than reported previously. This may provide insight into the underlying pathophysiologic process, tending to shorten the chordae tendineae and leaflets to produce stenosis rather than elongate them to produce prolapse.

Detection of type 2-like T-helper cells in hepatitis C virus infection: implications for hepatitis C virus chronicity

One striking clinical feature of hepatitis C virus (HCV) infection is that more than 50% of patients with acute hepatitis C will develop chronic infection. To investigate its possible mechanisms, we examined the activation of type 2-like T-helper (Th2-like) cells relating to the development of chronicity. Peripheral blood CD4+ T-cell proliferation and cytokine secretion in response to a panel of recombinant HCV antigens including core (C22), envelope 1 (E1), E2, nonstructural (NS) protein 4 (C100), fusion protein of NS3 and NS4 (C200), and NS5 were assayed in 17 patients with acute hepatitis C. All six patients with self-limited disease had a significant CD4+ T-cell proliferation to C22, E1, C100, C200, and NS5, running parallel with the antigen-stimulated secretion of interleukin (IL)-2 and interferon gamma (IFN-gamma), but not with interleukin (IL)-4 and IL-10, indicating predominant Th1 responses. Among the remaining 11 patients who developed chronicity, 6, 2, and 9 cases showed a specific CD4+ T-cell response to C22, C100, and C200, respectively, and the responses were significantly lower than those of cases with recovery in terms of stimulation index (SI) (P < .05) and of antigen-stimulated IL-2 and IFN-gamma production. Importantly, IL-4 and IL-10 (Th2 responses) were detectable, and C22-specific Th2-like T-cell clones could be generated from patients with chronicity. The data suggested that activation of Th2 responses in acute hepatitis C patients may play a role in the development of chronicity.

Cross-talk analysis of time-division multiplexing of polarization-insensitive fiber-optic Michelson interferometric sensors with a 3 x 3 directional coupler

A time division multiplexing of polarization-insensitive fiber-optic Michelson interferometric sensors (TDM-PIMI's) with a 3 x 3 directional coupler is presented. The elimination of polarization-induced fading and the output intensities of the TDM-PIMI system are described and demonstrated. The output intensity of each sensor of the system can be demodulated by a passive homodyne method to increase the sensor bandwidth significantly. The sensor cross talk of the system having an optical gate with a finite extinction ratio is analyzed. The use of a laser source with an adequate coherence length to reduce the sensor cross talk is suggested. The delay-fiber cross talk of the system by Rayleigh backscattering is analyzed and demonstrated. We further suggest some methods that could possibly reduce the effect of the Rayleigh backscattered light. Finally a sophisticated design of a TDM-PIMI system with a 3 x 3 directional coupler is described.

Prospective adaptive navigator correction for breath-hold MR coronary angiography

Current MR coronary angiography (MRCA) methods use breath-holding to minimize respiratory motion. A major limitation to this technique is misregistration between imaging slices due to breath-hold variability. Prospective adaptive correction of image location using real-time navigator measurement of diaphragm position is a potential method for improving slice registration in breath-hold MRCA. Ten subjects underwent MRCA using an ECG-gated, fat-suppressed, segmented k-space, gradient-echo sequence. Transverse and coronal images were acquired using standard breath-holding with and without prospective navigator correction. Breath-hold MRCA with prospective navigator correction resulted in a 47% reduction in craniocaudal slice registration error compared to standard breath-holding (0.9 +/- 0.2 mm versus 1.7 +/- 0.4 mm, P = 0.04). Prospective adaptive navigator correction of image location significantly improves slice registration for breath-hold MRCA and is a promising motion correction technique for cardiac MR.

Laparoscopically assisted abdominal aortic aneurysm repair. A report of 10 cases

BACKGROUND

Laparoscopic surgery decreases postoperative pain and length of hospital stay. Whether laparoscopically assisted abdominal aortic aneurysm (AAA) repair can be safely and reliably performed is unknown. This prospective study was designed to establish the feasibility of laparoscopically assisted AAA repair and its effects on intraoperative and postoperative variables.

METHODS

With IRB approval, 10 patients with infrarenal AAA requiring a tube graft underwent laparoscopically assisted AAA repair. The procedure consisted of laparoscopic dissection of the aneurysm neck and iliac vessels. Then, through an 8-11-cm minilaparotomy, a standard endoaneurysmorrhaphy was performed. Data included laparoscopic and total operative times, blood loss, fluid requirements, duration of nasogastric suction (NGT), and lengths of intensive care unit (ICU) and postoperative hospital stays.

RESULTS

Laparoscopically assisted AAA was completed in nine of 10 patients. The first patient was converted to a standard incision because the aneurysm neck could not be adequately dissected. Laparoscopic and total operative times were 1.8 +/- 0.4 and 4.5 +/- 0.7 h, respectively. Mean blood loss was 1 +/- 0.6 l. Intraoperative fluid requirement was 6.6 +/- 1.3 l. The duration of NGT suction was 1.8 +/- 1.0 days. The ICU stay was 2.1 +/- 0.8 days and hospital stay was 6.7 +/- 2.5 days. There were two minor complications and no deaths.

CONCLUSIONS

Laparoscopically assisted AAA repair is technically feasible with acceptable blood loss, operative time, morbidity, and mortality. Potential advantages may be early removal of the NGT and shorter ICU and hospital stays. Prospective randomized trials are needed to determine if laparoscopically assisted AAA repair is advantageous.

Antibacterial agents that inhibit lipid A biosynthesis

Lipid A constitutes the outer monolayer of the outer membrane of Gram-negative bacteria and is essential for bacterial growth. Synthetic antibacterials were identified that inhibit the second enzyme (a unique deacetylase) of lipid A biosynthesis. The inhibitors are chiral hydroxamic acids bearing certain hydrophobic aromatic moieties. They may bind to a metal in the active site of the deacetylase. The most potent analog (with an inhibition constant of about 50 nM) displayed a minimal inhibitory concentration of about 1 microgram per milliliter against Escherichia coli, caused three logs of bacterial killing in 4 hours, and cured mice infected with a lethal intraperitoneal dose of E. coli.

Laparoscopic aortic replacement in the porcine model: a feasibility study in preparation for laparoscopically assisted abdominal aortic aneurysm repair in humans

BACKGROUND

Current laparoscopic vascular techniques have centered around aortofemoral bypass for the treatment of patients with aortic occlusive disease. However, the majority of aortic surgeries are performed for the treatment of aortic aneurysmal disease. With this mind, we undertook this study to assess the feasibility of laparoscopic aortic replacement in the porcine model in preparation for laparoscopically assisted abdominal aortic aneurysm (AAA) repair in humans.

STUDY DESIGN

Twenty-three female pigs weighing between 35 and 40 kg underwent laparoscopic aortic dissection by either a transabdominal or retroperitoneal approach. The infrarenal aorta was laparoscopically dissected, isolated, and cross clamped. Then a custom designed cuffed polytetrafluoroethylene graft was inserted. After reestablishing and confirming distal flow, the animals were sacrificed.

RESULTS

Fifteen functioning aortic grafts were placed in 21 animals who had the transabdominal approach. One functioning graft was placed in the retroperitoneal group. Complications included bladder, ureteral, inferior vena cava, renal vein, and aortic injuries. By the end of the study, the operative time was reduced from six to less than two hours; blood loss was reduced from 1,000 to 150 mL; and cross-clamping time was reduced from 60 to 15 minutes.

CONCLUSIONS

In the porcine model, laparoscopic abdominal aortic replacement is associated with a significant learning curve. However, this method of repair is technically feasible and warrants further investigation in the treatment of AAA in humans.

A genetic defect in phosphatidylcholine biosynthesis triggers apoptosis in Chinese hamster ovary cells

We have investigated the cell death of a Chinese hamster ovary mutant (MT-58) with a thermo-sensitive CTP:phosphocholine cytidylyltransferase, the rate-limiting enzyme of the CDP-choline pathway for phosphatidylcholine biosynthesis (Esko, J. D., Wermuth, M. M., and Raetz, C. R. H. (1981) J. Biol. Chem. 256, 7388-7393). After MT-58 cells were shifted to the restrictive temperature of 40 degrees C, the cytidylyltransferase was inactivated immediately leading to a decrease in phosphatidylcholine biosynthesis and cell death. DNA content and number of cells in the S phase decreased significantly in the dying MT-58 cells according to flow cytometrical analyses. The fragmentation of genomic DNA was detected by DNA ladders in agarose gel and release of the prelabeled genomic DNA into cytosolic fractions 14 h after the temperature shift. The dying cells underwent a dramatic reduction of cellular volume while maintaining the membrane containment of cellular contents. These events indicated that the inactivation of cytidylyltransferase triggered apoptosis in Chinese hamster ovary cells. This is the first report that apoptosis was induced in cultured cells, not by an added agent, but by a mutation in phospholipid biosynthesis.

Effect of retinoic acid on wound healing of laser burns to porcine retinal pigment epithelium

OBJECTIVE

To determine the effect of retinoic acid on wound healing of laser burns to explants of porcine retinal pigment epithelium (RPE).

DESIGN

With the help of a mirrored attachment to a Coherent argon laser, laser burns (spot size 100 mu, power 500 mW, duration 0.2 seconds) were performed in 12 explants. The explants were then cultured in the presence (six explants) or absence (six explants) of 1 microM retinoic acid. Two explants in either group were recovered 4, 8 and 12 days after treatment for histologic study and scanning electron microscopy.

OUTCOME MEASURE

Mean burn area remaining after culture.

RESULTS

The area of wound remaining unhealed in the presence of retinoic acid was significantly larger than the area of wound remaining unhealed in the absence of retinoic acid at each time point.

CONCLUSIONS

Retinoic acid inhibited wound healing of laser burns to porcine RPE. This effect may illustrate a role for retinoic acid in the pharmacotherapy of proliferative disorders.

Cytotoxic effects of gemcitabine-containing regimens against human non-small cell lung cancer cell lines which express different levels of p185neu

A novel pyrimidine analogue, gemcitabine, has been found to inhibit DNA replication and repair. We speculated that gemcitabine in combination with DNA-damaging agents might be more active against high- than low-p185neu expressing non-small cell lung cancer (NSCLC) cells because the high-p185neu expressors were proposed to posses a more effective DNA repair ability. We therefore compared the combination effects of gemcitabine plus cisplatin, gemcitabine plus etoposide, and cisplatin plus etoposide in a panel of 12 NSCLC cell lines. We also investigated the correlations between the level of p185neu and the cytotoxicities of each single agent and the three combinations. We found that as single agents the cytotoxicities of cisplatin and etoposide but not gemcitabine were significantly correlated with the level of p185neu. In contrast to the tight cross-resistance between cisplatin and etoposide, gemcitabine demonstrated little cross-resistance to either etoposide or cisplatin. Both gemcitabine-containing combinations demonstrated equivalent or more active cytotoxicities compared to cisplatin plus etoposide, with gemcitabine plus cisplatin showing a greater synergistic activity which was effect (dose) dependent. The effect of cisplatin plus etoposide was not p185neu related, whereas gemcitabine-containing regimens, especially gemcitabine plus cisplatin, had a greater cytotoxicity against the high- than the low-p185neu expressors. Our findings indicate that gemcitabine in combination with cisplatin is active against NSCLC cells in vitro. The gemcitabine-cisplatin interaction is more active than the etoposide-cisplatin interaction in cells with high-p185neu expression.

Intracardiac echocardiography: in vitro and in vivo validation for right ventricular volume and function

To determine the feasibility and accuracy of intracardiac ultrasonography (ICUS) for the measurement of right ventricular (RV) volumes and function, a 10 MHz ICUS catheter was used in an in vitro and in vivo model. In the in vitro study, 16 sheep hearts were imaged. Sequential cross-sectional images from RV apex to base were recorded during a calibrated pullback. Volumes were calculated by applying Simpson's algorithm. ICUS-obtained volumes correlated well with actual volumes (standard error of estimate [SEE] = 2.3 ml, r = 0.98). For the in vivo study, a beating-heart canine model was used (31 hemodynamic stages in six dogs). Actual volumes were measured by an intracavitary balloon connected to an external column. Sequential cross-sectional images were recorded during the ICUS catheter pullback from apex to base of the RV, and volumes calculated by Simpson's algorithm. Good correlations were observed between ICUS and actual values for diastolic (SEE = 4.1 ml, r = 0.97), systolic (SEE = 3.4 ml, r = 0.96), and ejection fraction (SEE = 3.1%, r = 0.87) values. This new technique can accurately quantitate RV volumes, can function both in vitro and in vivo, and has the potential for increasing applications to questions of clinical and research interest.