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.

Purification and characterization of a naturally processed hepatitis B virus peptide recognized by CD8+ cytotoxic T lymphocytes

In vitro studies in patients with hepatitis B virus (HBV) infection have suggested that hepatocytolysis induced by CD8+ cytotoxic T lymphocytes (CTLs) is the most important effector pathway in eliminating infected cells. The recognition is implicated in the endogenously processed HBV antigens in the context of HLA class I molecules presented on the liver cell membrane. However, the naturally occurring HBV peptide antigens have not yet been demonstrated. We report here that a naturally processed peptide antigen P2 was isolated from HLA class I molecules of HBV-infected liver cell membrane. The P2 peptide exhibited the activity of sensitizing target cells for lysis by CD8+ CTLs. The P2 sequence (YVNVNMGLK) purified from liver tissue was in concordance with that encoded by the viral genome for the HBV nucleocapsid antigen or HBcAg 88-96. P2 peptide could also be isolated from the EBV-transformed B cells that were transfected by HBcAg-expressing vector. The P2 epitope, sharing the HLA-A11 binding motifs, was recognized by HLA-A11-restricted CD8+ CTLs. The data provided direct evidence that, in hepatitis B patients, antigenic peptides of HBV were processed by hepatocytes, presented with the class I MHC molecules, and recognized by CD8+ CTLs.

CTP: phosphocholine cytidylyltransferase is both a nuclear and cytoplasmic protein in primary hepatocytes

CTP:phosphocholine cytidylyltransferase (CT) has recently been reported to be a predominantly intranuclear enzyme in several cell lines (Wang et al., J. Biol. Chem. 268, 5899-5904 (1993)). This contrasts with previous reports that CT was a cytosolic protein that translocated to the endoplasmic reticulum upon activation. The aim of the present study was to compare the localization of CT in CHO cells and in primary rat hepatocytes. Indirect immunofluorescence of CHO cells revealed a largely nuclear localization of the CT. On the other hand, immunogold electron microscopy and biochemical studies showed a similar density of distribution of CT between the nucleus and cytoplasm. In primary rat hepatocytes immunofluorescence studies indicated that CT was largely cytoplasmic. Studies by immunogold electron microscopy of rat hepatocytes demonstrated that the enzyme was homogeneously distributed throughout all cytoplasmic regions and the nucleoplasm. This result was confirmed by biochemical studies using digitonin and streptolysin O, which permeabilizes the plasma membrane of cells. Enucleation studies indicated that in CHO cells 76% of the CT activity was in the nuclear fraction, whereas in hepatocytes only 32% was recovered in this fraction. The data indicate that CT is found both in nuclear and cytoplasmic fractions of primary hepatocytes and is not predominantly a nuclear enzyme.

Correlations between intrinsic chemoresistance and HER-2/neu gene expression, p53 gene mutations, and cell proliferation characteristics in non-small cell lung cancer cell lines

Using a panel of 20 non-small cell lung cancer (NSCLC) cell lines established from previously untreated patients, we investigated the relationships between intrinsic chemoresistance (to four agents used commonly in the therapy of NSCLC) and HER-2/neu gene expression (which encodes glycoprotein p185neu), p53 gene mutations, and cell proliferation characteristics. Our results demonstrated that high p185neu expression was correlated with chemoresistance, low S-phase fractions, and long doubling times. By contrast, cell lines expressing relatively low levels of p185neu were relatively chemosensitive and had higher S-phase fractions and shorter doubling times. Although mutation of the p53 gene was a common event in this panel of cell lines (present in 18 of 20 lines), there was no relationship between mutations at any specific codon and chemoresistance or cell proliferation characteristics. Multivariate analysis revealed that the level of p185neu was the only independent predictor for chemoresistance to doxorubicin, etoposide, and probably cisplatin. Although intrinsic chemoresistance almost certainly is a multifactorial process, overexpression of p185neu may be an important factor in the chemoresistance of NSCLC.

Effects of a program on symmetrical posture in patients with hemiplegia: A single-subject design

OBJECTIVES

Asymmetrical posture during static stance has been identified as a common problem in persons with hemiplegia. This study examined the effect of an activity-based therapy regimen on symmetric weight bearing and midline position of center of gravity (COG) in three adult subjects with hemiplegia.

METHOD

An ABAB single-subject design was used. The intervention program, including sanding in front of a standing table and play a bean bag game, was introduced for 30 min each day during each intervention phase. Quantitative measurements of the weight distribution and the midline position of COG were taken with the Balance Master System (version 2.20).

RESULTS

Visual inspection and statistical analysis of the data revealed a significant improvement in symmetric weight distribution and midline position of COG. The study suggests that this program may be a promising alternative to a variety of postural rehabilitation programs for persons with hemiplegia.

CONCLUSION

Insecurity caused by poor stabilization and abnormal reactions to body weight bearing in an antigravity position might contribute to asymmetric postures. Results of this study suggest that an activity-oriented program can be effective in helping the persons with hemiplegia achieve symmetric stances.

Structure of Saccharomyces cerevisiae alpha-agglutinin. Evidence for a yeast cell wall protein with multiple immunoglobulin-like domains with atypical disulfides

alpha-Agglutinin of Saccharomyces cerevisiae is a cell wall-associated protein that mediates cell interaction in mating. Although the mature protein includes about 610 residues, the NH2-terminal half of the protein is sufficient for binding to its ligand a-agglutinin. alpha-Agglutinin20-351, a fully active fragment of the protein, has been purified and analyzed. Circular dichroism spectroscopy, together with sequence alignments, suggest that alpha-agglutinin20-351 consists of three immunoglobulin variable-like domains: domain I, residues 20-104; domain II, residues 105-199; and domain III, residues 200-326. Peptide sequencing data established the arrangement of the disulfide bonds in alpha-agglutinin20-351. Cys97 is disulfide-bonded to Cys114, forming an interdomain bond between domains I and II. Cys202 is bonded to Cys300, in an atypical intradomain disulfide bond between the A and F strands of domain III. Cys227 and Cys256 have free sulfhydryls. Sequencing also showed that at least two of three potential N-glycosylation sites with sequence Asn-Xaa-Thr are glycosylated. At least one of three Asn-Xaa-Ser sequences is not glycosylated. No residues NH2-terminal to Ser282 were O-glycosylated, whereas Ser282, and all hydroxy amino acid residues COOH-terminal to this position were modified. Therefore O-glycosylated Ser and Thr residues cluster in the COOH-terminal region of domain III, and the O-glycosylation continues into a Ser/Thr-rich sequence that extends from domain III to the COOH-terminal of the full-length protein.

Homology modeling of an immunoglobulin-like domain in the Saccharomyces cerevisiae adhesion protein alpha-agglutinin

The Saccharomyces cerevisiae adhesion protein alpha-agglutinin is expressed by cells of alpha mating type. On the basis of sequence similarities, alpha-agglutinin has been proposed to contain variable-type immunoglobulin-like (IgV) domains. The low level of sequence similarity to IgV domains of known structure made homology modeling using standard sequence-based alignment algorithms impossible. We have therefore developed a secondary structure-based method that allowed homology modeling of alpha-aggulutinin domain III, the domain most similar to IgV domains. The model was assessed and where necessary refined to accommodate information obtained by biochemical and molecular genetic approaches, including the positions of a disulfide bond, glycosylation sites, and proteolytic sites. The model successfully predicted surface exposure of glycosylation and proteolytic sites, as well as identifying residues essential for binding activity. One side of the domain was predicted to be covered by carbohydrate residues. Surface accessibility and volume packing analyses showed that the regions of the model that have greatest sequence dissimilarity from the IgV consensus sequence are poorly structured in the biophysical sense. Nonetheless, the utility of the model suggests that these alignment and testing techniques should be of general use for building and testing of models of proteins that share limited sequence similarity with known structures.

Pharmacological and morphological effects of in vitro transluminal balloon angioplasty on normal and vasospastic canine basilar arteries

Despite growing clinical use of transluminal balloon angioplasty (TBA) to treat cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH), the precise mechanism of action of balloon dilation on the cerebral arterial wall is unknown. In this experiment the authors examined the pharmacological and morphological changes in 10 normal and 12 vasospastic canine basilar arteries following in vitro silicone microballoon TBA. For the SAH group in which the double-hemorrhage model was used, vasospasm was confirmed by angiography and the animals were killed on Day 7 after the first SAH. In vitro TBA was performed on basilar arteries from normal and SAH dogs immediately after sacrifice and removal of the brain. The procedure was performed while the arteries were maintained in oxygenated Krebs buffer. In the pharmacological studies, potassium chloride, prostaglandin F2 alpha, serotonin, and noradrenaline were used as vasoconstrictors, and bradykinin and calcium ionophore A23187 were used to produce an endothelium-dependent dilation. In both normal and vasospastic groups, the pharmacological responses of dilated segments of basilar arteries were compared to those of nondilated segments of the same arteries. Vessels from all groups were examined using scanning electron microscopy (EM) and transmission EM. Scanning EM was used to study the intact vessel wall, the smooth-muscle cell layer obtained after digestion with hydrochloric acid, and the extracellular matrix obtained after digestion with bleach. Cross-sections of the vessel wall were examined using transmission EM. The most striking finding was that immediately after in vitro TBA of both normal and vasospastic canine basilar arteries, there was a significant reduction (p < 0.05) of responses to both vasoconstrictors and vasorelaxants. As revealed by scanning EM and transmission EM, both normal and vasospastic vessels dilated with TBA showed flattening and patchy denudation of the endothelium, and straightening and occasional rupturing of the internal elastic lamina. In addition, vasospastic vessels dilated with TBA showed decreased surface rippling and mild stretching and straightening of smooth-muscle cells, and mild thinning of the tunica media. There was no gross vascular disruption or obvious change in the extracellular matrix of the vessel walls of either normal or vasospastic arteries after TBA. These results suggest that functional impairment of vasoreactivity in the vessel wall as a result of mechanical stretching of the smooth-muscle layer plays a more important role than structural alteration, at least in the immediate dilation produced in vasospastic arteries by TBA.

Incremental doses of dobutamine induce a biphasic response in dysfunctional left ventricular regions subtending coronary stenoses

BACKGROUND

Dobutamine stress echocardiography has been proposed as a diagnostic tool to identify viable myocardium. How regional wall thickening responds to dobutamine in the ischemic or short-term hibernating myocardium has not been adequately defined. We hypothesized that regional wall thickening would improve initially and subsequently deteriorate with incremental doses of dobutamine in viable myocardial regions supplied by a stenotic coronary artery. This study was undertaken to determine whether this biphasic pattern of regional function characterizes the response of ischemic or hibernating myocardium to dobutamine and to explore the factors and mechanisms that determine this response.

METHODS AND RESULTS

Twenty-six pigs in four groups were studied: a control group (n = 5) to assess the response of myocardium perfused by nonstenotic coronary artery to incremental doses of dobutamine, and three experimental groups with a left anterior descending coronary artery stenosis producing acute myocardial ischemia (n = 7), short-term myocardial hibernation for 90 minutes (n = 7), and short-term hibernation for 24 hours (n = 7) to determine the functional and metabolic response to dobutamine under these conditions. Regional coronary flow was reduced to 40% to 60% of baseline, with significant reductions of regional wall thickening as measured by two-dimensional echocardiography and sonomicrometers. An incremental dobutamine infusion from 2.5 to 25 micrograms.kg-1.min-1 increased wall thickening and coronary flow without lactate production in the control group. In the other three groups, during the incremental dobutamine infusion, regional wall thickening improved initially, from 11.4 +/- 7.5% to 19.8 +/- 11.4%, P < .01, at dobutamine doses of 2.5 to 10 (4.5 +/- 2.2) micrograms.min-1.kg-1 but deteriorated subsequently to 5.0 +/- 5.8% at the maximal dose of dobutamine of 12.6 +/- 4.1 micrograms.min-1.kg-1. The initial improvement of regional wall thickening was associated with a small increase in regional coronary flow (from 0.53 +/- 0.18 to 0.68 +/- 0.25 mL.min-1.g-1 myocardium, P < .05) and with regional lactate production. High doses of dobutamine did not further increase regional coronary flow but markedly increased lactate production and induced regional myocardial acidosis (pH 7.26 +/- 0.07). The biphasic pattern of response to dobutamine was observed in each of the three experimental groups. Both peak improvement and peak deterioration occurred earlier and at lower dobutamine dose levels in the group with acute ischemia compared with the group with short-term hibernation for 24 hours (P < .05).

CONCLUSIONS

A biphasic response of wall thickening to incremental dobutamine with initial improvement and subsequent deterioration is characteristic of ischemic or short-term hibernating myocardium. The initial low-dose dobutamine infusion improved wall thickening in the ischemic or hibernating myocardial region to a modest level. This initial modest improvement was transient and at the expense of metabolic deterioration of myocardial ischemia, so that at higher doses during prolonged dobutamine infusion, wall thickening deteriorated, lactate accumulated, and myocardial acidosis developed.

Laparoscopic-assisted abdominal aortic aneurysm repair

Since the advent of laparoscopy, the sweeping changes seen in general surgery have not been paralleled in vascular surgery. There have been case reports of laparoscopic-assisted aortobifemoral bypass for occlusive disease. Because aneurysmal disease comprises the majority of aortic surgery, we pursued animal and cadaveric feasibility studies for laparoscopic-assisted abdominal aortic aneurysm (AAA) repair. We present a case report of the first clinical case performed under Institutional Review Board protocol using this technique. The patient was a 62-year-old male with a 6-cm infrarenal AAA. After obtaining a pneumoperitoneum, a modified fish retractor was used to exclude the bowel. Ten 11-mm ports provided access to laparoscopically dissect the neck of the aneurysm and the iliac vessels. Then, a 10-cm minilaparotomy was performed and standard vascular clamps were inserted via the port incisions. Standard aneurysmorraphy was performed with a polytetrafluoroethylene (PTFE) tube graft. Laparoscopy conferred three major benefits: better visualization of the aneurysm neck, less bowel manipulation, and avoidance of hypothermia. This case report illustrates the feasibility of laparoscopic-assisted aneurysm repair. Controlled human studies will define the role of laparoscopy in AAA surgery.

Intracardiac ultrasonographic assessment of atrial septal defect area: in vitro validation and technical considerations

Assessment of atrial septal defect (ASD) size and shape is important for planning and guiding its transcatheter occlusion and can potentially be achieved by intracardiac ultrasonography (ICUS). ICUS accuracy, however, must first be established against stable standards and technical imaging requirements defined. We therefore used 10, 20, and 30 MHz ICUS catheters to examine 17 ASDs that were 0.16 to 6.7 cm2 in area and were surgically created in excised ovine hearts with 10, 20, and 30 MHz ICUS catheters. ASD shape and area by ICUS were compared with direct video images of the actual ASD. In all instances minimal area by ICUS pullback agreed well with actual values (y = 1.04x + 0.2, SEE = 0.23 cm2, r = 0.99) and corresponded well with defect shapes. The maximum angle between ultrasonography beam and septal plane allowing for complete ASD visualization was 20 degrees. The angle depended on transducer frequency and septal thickness. This new technique has potential value for the accurate assessment of ASD shape and size and may be especially useful in the setting of transcatheter occlusion.

Design and biological activities of L-163,191 (MK-0677): a potent, orally active growth hormone secretagogue

A potent, orally active growth hormone (GH) secretagogue L-163,191 belonging to a recently synthesized structural class has been characterized. L-163,191 releases GH from rat pituitary cells in culture with EC50 = 1.3 +/- 0.09 nM and is mechanistically indistinguishable from the GH-releasing peptide GHRP-6 and the prototypical nonpeptide GH secretagogue L-692,429 but clearly distinguishable from the natural GH secretagogue, GH-releasing hormone. L-163,191 elevates GH in dogs after oral doses as low as 0.125 mg/kg and was shown to be specific in its release of GH without significant effect on plasma levels of aldosterone, luteinizing hormone, thyroxine, and prolactin after oral administration of 1 mg/kg. Only modest increases in cortisol were observed. Based on these properties, L-163,191 has been selected for clinical studies.

Gastric atrophy and regional variation in upper gastrointestinal disease

OBJECTIVE

To compare the upper gastrointestinal disease profiles of Helicobacter pylori-infected patients drawn from two distinct regions of China, one with a low incidence of gastric cancer (Guangzhou) and the other with a high incidence of gastric cancer (Lanzhou). The age-standardized prevalence of H. pylori within the populations of these two cities was similar (approximately 56%). In these patient groups, the prevalence of different gastrointestinal disease states and the occurrence and severity of gastritis, gastric atrophy, and intestinal metaplasia were compared.

METHODS

This study was based on consecutive patients: 265 from Guangzhou and 275 from Lanzhou. The grading of gastritis and the detection of H. pylori was determined by histology using the "Sydney System".

RESULTS

The ratio of cases of duodenal to gastric ulceration for the two cities was: Guangzhou 14:1 and Lanzhou 3:1. Gastric cancer was more prevalent in the patients from Lanzhou (9.8%) than from Guangzhou (3%). In nonulcer dyspepsia patients from Guangzhou, gastritis was predominantly antral, whereas, in Lanzhou, gastritis was predominantly uniform. The amount and severity of atrophy was significantly greater in Lanzhou compared with Guangzhou.

CONCLUSIONS

The prevalence of atrophy, rather than age of acquisition and prevalence of H. pylori infection, appears to be a marker of the major upper gastrointestinal disease profiles of a region. Development of atrophy, although apparently related to H. pylori infection, may be a multifactorial condition. Differences in diet, as seen between Guangzhou and Lanzhou, may be important in this regard. Understanding the factors leading to the development of atrophy may enhance our understanding of processes leading to gastric malignancy.

The effect of cobalt-60 irradiation on bone marrow cellularity and alveolar osteoclasts

The purpose of this study was to investigate the mechanisms of bone resorption in the rat dentoalveolar complex occurring as a result of orthodontic appliance therapy. Utilizing whole body radioactive cobalt 60 (Co60) irradiation in combination with orthodontic tooth movement, the activation, recruitment, and life span of osteoclasts was studied. Thirty-four adult Fischer 344 rats were irradiated with 10 and 20 Gray of Co60. Twelve days after irradiation, each rat was fitted with an orthodontic appliance; the rats were sacrificed 7, 14, or 21 days after appliance placement. To serve as controls, another group of 12 rats was subjected to orthodontic treatment only. Histologic sections were prepared from decalcified maxillary alveolar process, and osteoclasts were counted. In the control group, osteoclasts were presence in the periodontal membrane for four weeks after appliance placement, and the largest number of osteoclasts was observed in the second week. The smaller total irradiation dose (10 Gray, administered in 5 daily fractions) induced a transient reduction in the bone marrow cell count of more than 90%, followed by a complete rebound. The peak osteoclst number also was increased 110%. In contrast, the higher total dose (20 Gray, administered in 10 daily fractions) resulted in a reduction of 60% in bone marrow cellularity and a decrease in the peak osteoclast number by 40%. Fluctuations in bone marrow cellularity generally corresponded to similar variations in the osteoclast number, but there was an apparent lack of correspondence between bone marrow cell and white blood cell values. The total period of osteoclastic presence in the periodontal membrane following orthodontic activation, normally four weeks in duration, was reduced by one week in the irradiated animals. These findings lead us to speculate that the mechanisms of osteoclast activation and recruitment following orthodontic appliance therapy may involve three consecutive waves of osteoclast maturation. The total duration of osteoclastic bone resorption lasts 4 weeks, but the osteoclast lie span is calculated to be 9 to 10 days (9 days x 3 waves = 27 days). If the results of this study are proved to be reproducible, a scientific basis may have been provided to support the common practice in orthodontics wherein the duration between orthodontic appointments is 4-5 weeks.

Time-division multiplexing of polarization-insensitive fiber-optic Michelson interferometric sensors

A system of time-division multiplexing of polarization-insensitive fiber-optic Michelson interferometric sensors that uses Faraday rotator mirror elements is demonstrated. This system is constructed with conventional low-birefringence single-mode fiber and is able to solve the polarization-fading problem by a combination of Faraday rotator mirrors with unbalanced Michelson interferometers. The system is lead-fiber insensitive and has potentials for practical field applications.

Pulsatile pressure affects the disappearance of echocardiographic contrast agents

The purpose of this study was to determine in an in vitro model the effect of pulsatile pressure on the decay of echocardiographic contrast agents. Use of contrast agents for quantitative assessment of perfusion requires understanding of the factors controlling their rates of disappearance. Prior studies have shown that constant pressure affects the rate of disappearance of these agents. It is not known whether pulsatile pressure influences the rate of decay of contrast agents. In an in vitro chamber, three contrast agents (Albunex, hand-agitated saline solution, and hand-agitated Angiovist) were exposed to pulses of pressure at three rates (30, 60, and 120 pulsations/min), keeping pressure characteristics (peak, nadir, and mean) within a narrow range. Five injections were performed for each agent at each rate. Two-dimensional echocardiographic images of the effects of contrast material were recorded from injection until total disappearance. Videointensity was measured and time-intensity curves were generated. These curves of intensity decay were fitted to an exponential decay function (I = Ae-lambda t) and the velocity of decay (lambda) was used for comparisons. For all agents, intensity of contrast decreased over time. Saline solution and Angiovist, but not Albunex, showed pulsatile decreases in intensity of contrast with each peak pressure and partial recovery of contrast intensity with each nadir pressure. (ABSTRACT TRUNCATED AT 250 WORDS)

Comparative cutaneous testing with purified protein derivative and the antigen complex A60 in vaccinated subjects and tuberculosis patients

Some 840 bacille Calmette-Guérin (BCG)-vaccinated healthy controls and tuberculosis patients from two Chinese hospitals were submitted to comparative skin tests with purified protein derivative of tuberculin (PPD; as reference) and with the antigen complex A60 from Mycobacterium bovis BCG. In a first trial, including 581 persons (185 healthy juveniles, 180 healthy adults and 216 tuberculosis patients), a limited dose of A60 (1 microgram) was used. Performance of the A60 test was similar to that of 5 I.U. PPD for controls (cut-off values = 5 mm induration diameter), but lower than that seen for tuberculosis patients (10 mm cut-off values). A second survey was conducted on 259 persons (109 recently revaccinated healthy persons, considered as tuberculin-negative in the first trial, and 150 tuberculosis patients), using a higher dose of A60 (2 micrograms) and the same dose of PPD (5 I.U.). Similar results were obtained with the two tests in all cases, thus supporting the possibility of PPD replacement by A60 in cutaneous testing. The pattern of induration diameter distribution in healthy subjects who took part in the first testing round (64% positively rate) was displaced to the inactivity side (with a peak at 5 to 9-mm diameter), in comparison with the second round (90% positivity rate and peak at 10-14 mm). This indicates a progressive fading of cellular immunity reactions after BCG vaccination. In tuberculosis patients, no correlation was found among the following three parameters: positivity at cutaneous testing (with PPD or A60), titer of anti-A60 mycobacterial immunoglobulins in blood (IgG titer higher than cut-off line) and presence of mycobacteria in sputum.

Sex differences in perioperative and long-term cardiac event-free survival in vascular surgery patients. An analysis of clinical and scintigraphic variables

BACKGROUND

Little information is available regarding the occurrence of perioperative and late cardiac events in women with vascular disease. The current study was performed to examine whether sex-specific differences exist in these outcomes in a large population of vascular surgery patients and to determine the value of clinical and dipyridamole thallium variables in predicting myocardial infarction and cardiac death.

METHODS AND RESULTS

Preoperative dipyridamole thallium imaging was performed in 567 vascular surgery patients, including 380 men and 187 women. The incidence of nonfatal myocardial infarction and cardiac death was noted during the perioperative period and during a follow-up period of 50 +/- 5 months. Fixed and reversible thallium perfusion abnormalities were more common in men than in women (P < .001 and P = .004, respectively). Perioperative cardiac event rates were similar in men and women, 8.4% and 7.5%, respectively (P = .07). A transient thallium defect was associated with an increased risk of cardiac events by 3.9-fold in men (CI, 1.5 to 10.2) and 5.5-fold in women (CI, 1.4 to 22). Various clinical factors also were predictive of events but demonstrated substantial sex differences. For example, dipyridamole-induced ST-segment depression was strongly associated with perioperative events in men but not in women. There were 22 nonfatal myocardial infarctions and 29 cardiac deaths in men during the follow-up period, with comparable event rates noted for women. Cardiac event-free survival rates also were similar for men and women (P = .40). Multivariate analysis demonstrated that a history of heart failure was an important prognostic variable for both sexes, as was a fixed thallium defect. Significant sex differences in the predictive value of other clinical factors for late cardiac events was apparent.

CONCLUSIONS

The present study demonstrates that (1) thallium perfusion defects are more common in men; (2) transient thallium defects are associated with perioperative myocardial infarction and cardiac death in both sexes; (3) long-term survival rates after vascular surgery are similar between men and women; (4) a fixed perfusion defect is predictive of late cardiac events in women, with a trend noted in men; and (5) sex-specific differences were noted with regard to the prognostic value of various clinical risk factors. Therefore, dipyridamole thallium plays a significant role in the assessment of perioperative and long-term prognosis for both male and female vascular surgery patients. On the basis of these observations, modifications in risk stratification based on sex may be appropriate for men and women with vascular disease.

Helicobacter pylori associated with a high prevalence of duodenal ulcer disease and a low prevalence of gastric cancer in a developing nation

This study examines the relationship between Helicobacter pylori infection and peptic ulcer disease and gastric cancer--in particular, the presence or absence of bacteria, the grading of gastritis, and the degree of inflammation in the antral and oxyntic mucosae. The grading of gastritis and the detection of H pylori were determined by histology using the Sydney system. Of the 1006 patients examined, 34.5% had duodenal ulcer disease, 3.5% gastric ulcer disease, and 2% with coexistent ulceration. Most patients (50.2%) were classified as having non-ulcer dyspepsia. Altogether 2.4% of patients had gastric cancer and two further patients had carcinoma in the gastric stump. Of the ulcer disease patients, 87.2% had histological evidence of H pylori infection. After patients who had taken antibiotics or bismuth compounds in the preceding four weeks were excluded, 98.9% of the duodenal ulcer disease, 100% of the gastric ulcer disease, and 100% of the coexistent ulcer disease patients had evidence of H pylori infection. In patients with gastric cancer who had not taken antimicrobial agents in the four weeks before endoscopy, 83.3% had evidence of H pylori infection. Thus, there was a high rate of duodenal ulcer disease and a low rate of gastric ulcer disease in southern China, an area of low gastric cancer mortality. There was a specific topographical relationship between H pylori, the histological response, and gastroduodenal disease. Our data suggest that the status of a nation as either 'developed' or 'developing' can not be used to predict the upper gastrointestinal disease profile of its population.

Serological analysis of pulmonary and extrapulmonary tuberculosis with enzyme-linked immunosorbent assays for anti-A60 immunoglobulins

IgA, IgG, and IgM antibodies to mycobacterial antigen A60 were measured by ELISA in blood, pleural fluid, and cerebrospinal fluid from 560 patients with pulmonary and/or extrapulmonary tuberculosis who were being treated at hospitals in northern China and from 734 uninfected controls. Among 529 healthy persons (most of whom had been vaccinated with bacille Calmette-Guérin [BCG] and 287 of whom were tuberculin-positive), the rate of false-positive results was negligible; this observation ruled out interference of remote BCG vaccination with A60 assays at the chosen cutoff level. Rates of positivity for IgM and IgG, respectively, were 80% and 36% among patients with active primary pulmonary tuberculosis, 31% and 88.5% among patients with active postprimary pulmonary tuberculosis, 0 and 41% among patients with inactive pulmonary tuberculosis, and 30%-61% and 69%-86% among patients with extrapulmonary tuberculosis. Paired samples of blood and pleural fluid from patients with pleurisy contained IgA antibody to A60 at equal titers; in contrast, most patients with tuberculous meningitis (100% of whom had a positive ELISA result) had higher levels of IgG antibody to A60 in cerebrospinal fluid than in blood--proof of intrathecal synthesis.

A unique mitochondria-associated membrane fraction from rat liver has a high capacity for lipid synthesis and contains pre-Golgi secretory proteins including nascent lipoproteins

An endoplasmic reticulum-like membrane fraction, termed the "mitochondria-associated membrane" (MAM), that co-isolates with mitochondria from rat liver has been characterized. One potential function of the MAM is as a membrane bridge between the endoplasmic reticulum and mitochondria that may be involved in transfer of phospholipids between these two organelles (Vance, J. E. (1990) J. Biol. Chem. 265, 7248-7256). A polyclonal antibody directed against a peptide corresponding to the C terminus of phosphatidylethanolamine N-methyltransferase-2, a specific marker protein of the MAM (Cui, Z., Vance, J. E., Chen, M. H., Voelker, D. R., and Vance, D. E. (1993) J. Biol. Chem. 268, 16655-16663), was used in immunofluorescence and immunogold electron microscopy localization studies in rat hepatocytes. Immunoreactive protein was clustered in regions of the cell that did not correspond to the bulk of endoplasmic reticulum. A second potential role for the MAM, as a component of the secretory pathway that supplies lipids for assembly into very low density lipoproteins, has been examined. The MAM contains enzymes of similar, or higher, specific activities to those enzymes in the endoplasmic reticulum for the synthesis of phospholipids, triacylglycerols, cholesterol, and cholesteryl esters. Specific activities of diacylglycerol acyltransferase, acyl-coenzyme A:cholesterol acyltransferase, and phosphatidylserine synthase (base exchange enzyme) are enriched 2.2-3.4-fold in the MAM compared with endoplasmic reticulum. In addition, the microsomal triacylglycerol transfer protein, which is required for the assembly/secretion of apolipoprotein B-containing lipoproteins, was present in the MAM. Nascent apolipoprotein B-containing lipoproteins were isolated from the lumen of the MAM. These lipoproteins had the same average density and composition as nascent apolipoprotein B-containing lipoproteins isolated from heavy and light endoplasmic reticulum fractions, from the Golgi, and lipoproteins newly secreted by cultured rat hepatocytes. The MAM is a pre-Golgi compartment of the secretory route, as shown by pulse-chase studies with apolipoprotein B and albumin, as well as the sensitivity of luminal apolipoprotein B to endoglycosidase H.

Expression of alpha-amylases, carbohydrate metabolism, and autophagy in cultured rice cells is coordinately regulated by sugar nutrient

A rice suspension cell culture system has been established to study how sugar depletion regulates alpha-amylase expression, carbohydrate metabolism, and other physiological and cellular changes. It is shown here that a group of 44 kDa alpha-amylases are constitutively expressed whether or not the cells are starved of sucrose. However, expression of a new group of alpha-amylases of 46 kDa is dramatically induced when cells are starved of sucrose. Cellular sugar and starch were rapidly consumed and metabolic activity was decreased in the starved cells. Extensive autophagy also occurred in the starved cells, which caused an increase in vacuolar volume and degradation of cytoplasmic constituents including amyloplasts. Immunocytochemical studies revealed that alpha-amylases are localized in starch granules within amyloplasts, in cell walls, and in some of the vacuoles. The presence of putative signal sequences in the N-termini of nine rice alpha-amylases suggests hitherto unidentified pathways for import of alpha-amylases into amyloplasts. The studies show that differential alpha-amylase expression, carbohydrate metabolism, metabolic activity, and vacuolar autophagy are coordinately regulated by the sugar level in the medium. As the starved suspension cells exhibit some sugar-regulated characteristics of alpha-amylase expression in germinating rice embryos as well as physiological changes similar to those in senescing cells, this system represents an ideal tool for studying cellular, biochemical, and molecular biological aspects of alpha-amylase gene regulation, carbohydrate metabolism, senescence, and protein targeting in plants.

Intracardiac ultrasound measurement of volumes and ejection fraction in normal, infarcted, and aneurysmal left ventricles using a 10-MHz ultrasound catheter

BACKGROUND

Our objective was to examine the accuracy of intracardiac ultrasound (ICUS) measurement of left ventricular (LV) volumes and ejection fraction (EF) using a 10-MHz ultrasound catheter. ICUS can image the LV in cross sections at all levels along the long axis with a transducer mounted on the tip of a catheter. Sequential serial LV cross-sectional images can be obtained during cardiac catheterization and used to calculate LV volumes by Simpson's rule. This technique may be an alternative to contrast LV angiography.

METHODS AND RESULTS

A beating-heart in vivo model was created to measure LV volume directly and continuously with an intracavity high-compliance latex balloon connected to a calibrated extracardiac reservoir in eight dogs in 35 experimental stages. A 10F ICUS catheter with a 10-MHz single-element transducer was introduced retrogradely via the aortic valve to the apex. Series of sequential LV cross-sectional images were recorded from the apex to the base during a calibrated pullback of the catheter. At each 5-mm interval, the LV cross section was traced at end diastole and end systole. LV volume was calculated by Simpson's rule by integrating all segmental areas multiplied by segmental height. The effect on accuracy of selecting 5-, 10-, or 15-mm heights or a single section at the midventricular level for measurement was assessed. The influence of distorted ventricular shape on the accuracy of ICUS measurements of LV volume was evaluated. This method was applied in 19 experimental stages in 10 intact dogs and pigs catheterized via the femoral artery. In the in vivo canine model, LV end-diastolic volume, end-systolic volume, and EF determined by ICUS using 5-, 10-, or 15-mm segments were not different from the actual measurements. But correlation and agreement between ICUS end-diastolic volume and direct measurements for 5- and 10-mm segments were significantly better than for 15-mm segments or a single section. Similar excellent correlations and agreement were observed for actual and ICUS-derived end-systolic volumes using 5-, 10-, or 15-mm segments. The ICUS-derived EF correlated very well with actual EF with a small measurement error of 3.91 +/- 2.59% for 5-mm or 4.13 +/- 2.79% for 10-mm segments but a significantly greater measurement error for 15-mm segments (5.35 +/- 3.76%) or single sections (14.8 +/- 12.2%). The presence of LV infarction or aneurysm did not significantly influence the accuracy of ICUS calculations for segmental heights < or = 10 mm. Application in intact animals demonstrated a good correlation between stroke volume measured by ICUS and by thermodilution or flowmeter. ICUS-derived LV volumes correlated well with biplane angiographic volumes, with a tendency toward underestimation. There was no significant difference between ICUS-determined LV EF and EF determined by angiography.

CONCLUSIONS

Intracardiac echocardiography accurately measures LV volumes and global systolic function in both regularly shaped and distorted left ventricles. This technique directly and continuously visualizes circumferential LV endocardium and wall thickness without contrast agents or geometric assumptions for calculation of LV volume. Thus, it should be particularly useful in patients at high risk for contrast-related complications or distorted LV shapes in which geometric assumptions may not be valid.

[Manifestation of abdominal segment of esophagus by body surface ultrasonography and determination of normal values]

Scanning over the oblique section of xiphoid-left costal margin by body surface ultrasonography was adopted in the present study. The esophageal hiatus showed triangle-like strong echo which was called by the author "Hom Dill Casoue". Its dorsal aspect could be confirmed as the abdominal segment of the esophagus. In a general survey of 268 cases of high risk crowd in high incidence area, 82% (217 cases) were manifested clearly. The mean wall thickness was 2.58 +/- 0.54mm, and the mean length 23.7 +/- 5.6mm. Among the 9 cases suspicious of increased thickness, 5 were confirmed to have esophageal lesions. Among them there were 2 cases of esophageal carcinoma, and 2 cases of inflammatory ulcer with edema, and one case of hiatal hernia. The accuracy rate of diagnosis for those with clear manifestation by ultrasonography reached as high as 98% (218/222 cases). This method provides a new measure for the general survey of esophageal diseases in the abdominal segment.

[The clinical significance of detection of anti-BCG-A60 antibody by ELISA in diagnosis of tuberculosis]

In order to find out the clinical significance of detection of BCG-A60 antibody by ELISA in diagnosis of tuberculosis, 734 cases of non-tuberculosis patients and 560 cases of tuberculosis has been examined. The result of A60-ELISA test for IgG as diagnosilic criteria of tuberculosis, sensitivity is 84.5%, specificity is 89.3%, It shows satisfactory effect, so it can be used as an helpful method in clinical diagnosis of tuberculosis. IgG, IgA and IgM are measured at same time, and find that a combined use of the IgG and IgM ELISA studies considerably increases the significance of the test.

Transcutaneous ultrasound of the cervical esophagus in patients with esophageal carcinoma

Transcutaneous ultrasound of the cervical esophagus was performed in 46 patients with esophageal carcinoma and in 35 controls. The former had 24 upper segmental lesions and 22 lower segmental lesions. The level of the sternoclavicular joint was used to divide the esophagus into the upper segmental (USE) and lower segmental esophagus (LSE). The anterior esophageal wall thickness and luminal dimensions were measured before and immediately after phonation. The mean wall thickness in the controls was 1.8 mm before phonation and 2.1 mm after phonation, with a significant difference (t test, P < 0.05). The mean wall thickness in the USE carcinoma group was 4.3 mm and 4.4 mm before and after phonation respectively. There was a significant difference between the controls and USE carcinoma groups (t test, P < 0.05). The cross sectional area, which was calculated as the product of anterio-posterior and lateral diameters, averaged 28 mm2 before phonation in the controls and increased to 44 mm2 after phonation (t test, P < 0.05). The mean cross sectional area in the USE carcinoma group was significantly smaller before phonation than that in the controls (t test, P < 0.05) and showed little change after phonation. No significant difference was found between LSE carcinoma and control groups. Transcutaneous ultrasound appears to be a promising non-invasive method of investigation for cervical esophageal carcinoma.

In vivo measurements of frequency-dependent attenuation in tumors of the liver

Ultrasonic frequency-dependent attenuation (FDA) coefficients of the liver obtained from selected regions of interest within the liver were determined in 106 individuals, 40 cases presumed normal based on medical histories and 66 with malignant tumors (hepatocellular carcinoma [HCC] or metastatic liver tumor) or benign tumors (hepatic hemangioma, hepatic adenoma, or focal nodular hyperplasia of the liver). All liver tumors were confirmed histopathologically by ultrasonically guided fine-needle biopsy and/or operation. Mean attenuation of normal liver was 0.53 +/- 0.03 dB/cm/MHz, 0.29 +/- 0.05 dB/cm/MHz in hepatic hemangioma, 0.43 +/- 0.05 dB/cm/MHz in HCC, and 0.41 +/- 0.12 dB/cm/MHz in metastatic liver tumor. Hepatic adenoma and focal nodular hyperplasia of the liver produced higher values, averaging 0.66 +/- 0.09 dB/cm/MHz. This difference between malignant and benign tumors was statistically significant. There was some correlation between the FDA for the hepatic tumor and the histopathology that merits further investigation.

Thoracic epidural anesthesia for major abdominal surgery: a retrospective study

In 1986-1988, the authors had experiences with thoracic epidural anesthesia for a variety of major abdominal operations in 303 patients. It is proved to be reliable and effective. The puncture levels were between T8 to T12. 2% lidocaine, in plain form or with 1:200,000 epinephrine, was used as anesthetic agent. Perioperative complications were carefully managed with satisfactory results. Post-operative conditions were evaluated and seemed to be superior to those of general anesthesia in many aspects. No patient had neurologic deficit as a result of the epidural anesthesia. We concluded that thoracic epidural anesthesia is an excellent alternative technique in major abdominal surgeries.