Concerning the ultrastructural origin of large-scale swelling in articular cartilage

The swelling behaviour of the general matrix of both normal and abnormally softened articular cartilage was investigated in the context of its relationship to the underlying subchondral bone, the articular surface, and with respect to the primary structural directions represented in its strongly anisotropic collagenous architecture. Swelling behaviours were compared by subjecting tissue specimens under different modes of constraint to a high swelling bathing solution of distilled water and comparing structural changes imaged at the macroscopic, microscopic and ultrastructural levels of resolution. Near zero swelling was observed in the isolated normal general matrix with minimal structural change. By contrast the similarly isolated softened general matrix exhibited large-scale swelling in both the transverse and radial directions. This difference in dimensional stability was attributed to fundamentally different levels of fibril interconnectivity between the 2 matrices. A model of structural transformation is proposed to accommodate fibrillar rearrangements associated with the large-scale swelling in the radial and transverse directions in the softened general matrix.

Syntheses and biological activities of chiral piperidines-tachykinin NK3 antagonists

AIM

To develop nonpeptide tachykinin NK3 antagonists.

METHODS

Five tachykinin NK3 antagonists were synthesized. Receptor binding assay and oral absorption study were made.

RESULTS

The 4,4-disubstituted piperidine compounds (1b, 1c, and 1d) showed stronger activities (IC50 = 5.9, 6.2, and 11 nmol.L-1, respectively) than the monosubstituted ring compound 1e (IC50 = 17 nmol.L-1). 4-Phenyl (1b) and 4-phenylsulfonylmethyl (1c) compounds were more active than the 4-fluorobenzyl compound (1d). All antagonists were found to be orally absorbable, the T1/2 of 1b (6.4 h) was more than three-fold longer than that of 1a (1.9 h).

CONCLUSION

Compound 1b had the best binding activity (IC50 = 5.9 nmol.L-1) and the best AUC (2081 micrograms.h.L-1).

Osteoclast activation and recruitment after application of orthodontic force

In this study, whole body radioactive cobalt 60 (Co60) irradiation was used in an orthodontic tooth movement model to investigate osteoclast activation and recruitment in adult rats. Seventy-five rats were divided into three groups and were irradiated with Co60 ranging from 10 to 26 Gray. An orthodontic appliance was fitted to each rat 12 days after initiation of irradiation. Identical appliances were fitted on an additional 25 unirradiated rats. Groups of rats were sacrificed 1 week before and on the day of appliance placement as well as 1, 2, 3, 4, or 5 weeks after appliance placement. Histologic sections from decalcified maxillary processes were prepared and osteoclasts were counted. Results showed that regardless of irradiation dosage, osteoclast number did not decrease during the first 3 weeks of orthodontic treatment; animals receiving lower (ie, 10 Gray) total irradiation actually showed a transient increase in the osteoclast number. In addition, regardless of dose in the irradiated rats, the total time osteoclasts were present in the periodontal membrane after orthodontic activation was reduced from 4 to 3 weeks. These findings lead us to hypothesize that osteoclasts involved in appliance-induced remodeling are initially from precursors in the periodontal membrane. During prolonged periods of orthodontic force application, replacement osteoclasts originate from bone marrow precursors. Although an orthodontic bone resorption cycle lasts 4 weeks, the life span of individual osteoclasts is limited to 9 to 10 days. The clinical significance of this finding remains to be elucidated.

Carbohydroxamido-oxazolidines: antibacterial agents that target lipid A biosynthesis

A series of carbohydroxamido-oxazolidine inhibitors of UDP-3-O-[R-3-hydroxymyristoyl]-GlcNAc deacetylase, the enzyme responsible for the second step in lipid A biosynthesis, was identified. The most potent analog L-161,240 showed an IC50 = 30 nM in the DEACET assay and displayed an MIC of 1-3 microg/mL against wild-type E. coli.

Pretreatment nomogram for prostate-specific antigen recurrence after radical prostatectomy or external-beam radiation therapy for clinically localized prostate cancer

PURPOSE

To present nomograms providing estimates of prostate-specific antigen (PSA) failure-free survival after radical prostatectomy (RP) or external-beam radiation therapy (RT) for men diagnosed during the PSA era with clinically localized disease.

PATIENTS AND METHODS

A Cox regression multivariable analysis was used to determine the prognostic significance of the pretreatment PSA level, 1992 American Joint Committee on Cancer (AJCC) clinical stage, and biopsy Gleason score in predicting the time to posttherapy PSA failure in 1,654 men with T1c,2 prostate cancer managed with either RP or RT.

RESULTS

Pretherapy PSA, AJCC clinical stage, and biopsy Gleason score were independent predictors (P < .0001) of time to posttherapy PSA failure in patients managed with either RP or RT. Two-year PSA failure rates derived from the Cox regression model and bootstrap estimates of the 95% confidence intervals are presented in the format of a nomogram stratified by the pretreatment PSA, AJCC clinical stage, biopsy Gleason score, and local treatment modality.

CONCLUSION

Men at high risk (> 50%) for early (< or = 2 years) PSA failure could be identified on the basis of the type of local therapy received and the clinical information obtained as part of the routine work-up for localized prostate cancer. Selection of these men for trials evaluating adjuvant systemic and improved local therapies may be justified.

Heritability estimates from human twin data by incorporating historical prior information

Bayesian methods are commonly used in some analyses of human genetic data, such as segregation and linkage analyses, but they are not typically used for analyses of human twin data. In this paper we develop a scheme for a Bayesian analysis of human twin data. We develop prior elicitation schemes to incorporate historical information. We consider three prior schemes: fully informative, semi-informative and noninformative. We use Markov chain Monte Carlo sampling algorithms to facilitate Bayesian computation and provide detailed implementation schemes. We also develop model diagnostics for assessing the goodness of fit of twin models. Using a simulation study, we show that if the purpose of the study is to estimate the intraclass correlations or heritability in twin studies, then the semi-informative prior is as informative as the fully informative prior. Finally, a real data example is used to illustrate the proposed methodologies.

The combination of preoperative prostate specific antigen and postoperative pathological findings to predict prostate specific antigen outcome in clinically localized prostate cancer

PURPOSE

The independent clinical and pathological predictors of time to postoperative prostate specific antigen (PSA) failure were used to identify prostate cancer patients at high risk for this end point.

MATERIALS AND METHODS

A Cox regression multivariate analysis was used to determine the prognostic significance of preoperative PSA, pathological stage, prostatectomy Gleason score and margin status in predicting the time to postoperative PSA failure in 862 men with palpable (T2) or PSA detected (T1c) prostate cancer. The 2-year PSA failure rates with 95% confidence intervals were calculated using the results of Cox regression analysis and a bootstrap procedure with 2,000 replications, respectively, and are presented in nomogram format stratified by preoperative PSA, pathological stage, prostatectomy Gleason score and margin status.

RESULTS

Preoperative PSA (p = 0.0001), pathological stage (p< or =0.002), margin status (p = 0.0001) and prostatectomy Gleason score (p = 0.034) were independent predictors of time to postoperative PSA failure.

CONCLUSIONS

Patients at high risk for early PSA failure could be identified postoperatively on the basis of preoperative PSA and prostatectomy pathology. Adjuvant therapy trials in these select patients may be justified.

De novo unbalanced translocation resulting in monosomy for proximal 14q and distal 4p in a fetus with intrauterine growth retardation, Wolf-Hirschhorn syndrome, hypertrophic cardiomyopathy, and partial hemihypoplasia

We present the perinatal findings of a fetus with a de novo unbalanced chromosome translocation that resulted in monosomy for proximal 14q and monosomy for distal 4p. Prenatal sonographic examination at 27 weeks of gestation showed intrauterine growth retardation, microcephaly, cardiomegaly with arrhythmia, and asymmetry of the upper limbs. Genetic amniocentesis showed an abnormal karyotype of 45,XX,der(4)t(4;14)(p16.3;q12),-14. Linkage analysis of the family confirmed the maternal origin of the deletions. Molecular refinement of the deletion breakpoints indicated that the breakpoints at 4p16.3 and 14q12 were located between loci D4S403 (present) and D4S394 (absent), and between loci D14S252 (present) and D14S64 (absent), respectively. Necropsy showed dysmorphic features compatible with Wolf-Hirschhorn syndrome, hypertrophic cardiomyopathy, partial hemihypoplasia, and a normal brain without evidence of holoprosencephaly. Our case adds to the list of clinical phenotypes associated with the proximal regions of 14q.

Analyzing outcome-based staging for clinically localized adenocarcinoma of the prostate

BACKGROUND

A clinical staging system based on the prostate-specific antigen (PSA) and the calculated prostate carcinoma volume (cVCa) construct previously has been proposed. This study was performed to assess whether this proposed clinical staging system was valid in an independent surgical and radiation data set in patients with clinically localized disease.

METHODS

Cox regression multivariable analyses were used to assess the significance of staging systems (1992 American Joint Commission on Cancer Staging [AJCC] clinical and pathologic stage, versus cVCa-PSA clinical stage) to predict time to posttherapy PSA failure in 441 and 465 patients managed by surgery and radiation, respectively. Significant staging systems identified using Cox regression were tested further using established comparative measures to define the most clinically useful system.

RESULTS

Both the 1992 AJCC pathologic stage and the cVCa-PSA clinical stage were significant predictors of time to postoperative PSA failure (P = 0.0001), whereas only the cVCa-PSA clinical stage was a significant predictor of time to postradiation PSA failure (P = 0.0001) using a Cox regression multivariable analysis. Further analyses using a pairwise comparison of the 1992 AJCC pathologic stage and cVCa-PSA clinical stage found the cVCa-PSA staging system provided a more clinically useful prediction of time to postoperative PSA failure. Specifically, the cVCa-PSA staging system was able to identify surgically managed patients with pathologic AJCC T2 disease who did poorly (3-year bNED = 22%) while also selecting patients with clinical AJCC T2b,c disease that was managed by radiation who did well (3-year bNED = 100%).

CONCLUSIONS

A clinical staging system based on parameters obtained during the routine evaluation for AJCC clinical T1,2 prostate carcinoma provided a clinically useful stratification of both postoperative and postradiation PSA failure free survival.

Hepatitis C virus variants circumventing cytotoxic T lymphocyte activity as a mechanism of chronicity

BACKGROUND & AIMS

High rate of chronicity after acute hepatitis C virus (HCV) infection cannot be explained in the presence of a multispecific cytotoxic T lymphocyte (CTL) response. The aim of this study was to investigate the effect of virus variants on CTL activity in patients in whom chronicity developed.

METHODS

CTL clones specific to a decapeptide epitope derived from hypervariable region 1 were generated from 5 HLA-A2-positive patients with acute hepatitis C by in vitro stimulation with synthetic peptides. The sequential change of this CTL epitope and its influence on the CTL recognition were examined.

RESULTS

Virus variants did not appear in 3 patients with recovery, whereas variants with altered peptide ligands capable of antagonizing CTL activity emerged rapidly in the remaining 2 patients in whom chronicity developed. Importantly, these HLA-A2-restricted, hypervariable region 1-specific CTL clones shared the use of T-cell receptor (TCR) genes AV6 and BV17.

CONCLUSIONS

These data suggest that there is only a narrow T-cell repertoire responding to a single viral peptide/HLA ligand. The emergence of HCV variants with altered peptide ligands as TCR antagonists accompanied by a limited TCR repertoire may provide a mechanism for HCV chronicity.

Hypertrophic remodeling: gender differences in the early response to left ventricular pressure overload

OBJECTIVES

To identify gender differences in left ventricular remodeling, hypertrophy, and function in response to pressure overload due to ascending aortic banding in rats.

BACKGROUND

Gender may influence the adaptation to pressure overload, as women with aortic stenosis have greater degrees of left ventricular hypertrophy and better left ventricular function than men.

METHODS

Fifty-two weanling rats underwent ascending aortic banding (16 males, 18 females), or sham surgery (9 males, 9 females). At 6 and 20 weeks, rats underwent transthoracic echo Doppler studies, and closed-chest left ventricular pressures with direct left ventricular puncture. Perfusion-fixed tissues from eight rats were examined morphometrically for myocyte cross-sectional area and percent collagen volume.

RESULTS

At 6 weeks after aortic banding, left ventricular remodeling, extent of hypertrophy, and function appeared similar in male and female rats. At 20 weeks, male but not female rats showed an early transition to heart failure, with onset of cavity dilatation (left ventricular diameter=155% vs. 121% of same-sex sham), loss of concentric remodeling (relative wall thickness=102% vs. 139% of sham), elevated wall stress (systolic stress=266% vs. 154% of sham), and diastolic dysfunction (deceleration of rapid filling=251% vs. 190% of sham). Left ventricular systolic pressures were higher in female compared with male rats (186+/-20 vs. 139+/-13 mm Hg), while diastolic pressures tended to be lower (14+/-4 vs. 17+/-4 mm Hg).

CONCLUSIONS

Gender significantly influences the evolution of the early response to pressure overload, including the transition to heart failure in rats with aortic stenosis.

Effectiveness of slow-release lanreotide, a long-acting somatostatin analogue, in the treatment of acromegaly

We evaluated the effectiveness of slow-release lanreotide, a long-acting somatostatin analogue, in the treatment of acromegaly. Eleven patients with acromegaly were recruited, six of whom had received long-term treatment with octreotide. Lanreotide 30 mg was administered by intramuscular injection every other week for 24 weeks. The frequency of injection was adjusted as clinically needed after 2 weeks. Clinical effects were evaluated, and symptoms were recorded and scored. Finger circumferences and hand volumes were measured. Serum growth hormone (GH) and insulin-like growth factor-1 (IGF-1) concentrations were determined, and an oral glucose test was done at baseline and after treatment. Symptom scores, circumferences of the fingers, hand volumes, and serum GH and IGF-1 concentrations significantly decreased during treatment. Serum GH concentrations returned to normal in five (46%) of the 11 patients, while serum IGF-1 concentrations returned to normal in three (27%). Glucose intolerance was not significantly improved at the end of treatment. Although the mean serum GH concentration was significantly decreased after treatment, it was still not suppressed by glucose. In conclusion, slow-release lanreotide, given either twice or three times a month, is effective in controlling acromegalic symptoms as well as GH and IGF-1 hypersecretion. The treatment is well tolerated and convenient for patients.

Changes in reproductive hormones and sex hormone-binding globulin in a group of postmenopausal women measured over 10 years

OBJECTIVE

As part of a study on hormones and bone density in older women, we measured a number of steroid and polypeptide hormones at 4- to 6-month intervals in 32 women over a 10-year period.

DESIGN

All women were postmenopausal during this time and all measurements from 12 months after the menopause to the end were used in the analysis. To determine whether there was a significant trend in steroid or polypeptide hormones over the years, the data were analyzed by random coefficient linear regression against number of months since menopause.

RESULTS

There was no significant trend in the concentrations of estrone, estrone sulfate, dehydroepiandrosterone, and follicle stimulating hormone. There was a significant decline in the concentrations of estradiol, dihydrotestosterone, dehydroepiandrosterone sulfate, and luteinizing hormone. There was a rise in the levels of androstenedione and testosterone.

CONCLUSIONS

The changes in the concentration of sex hormone-binding globulin could be fitted to a quadratic equation with an initial rise in the concentration followed by a decline. Thus, the trend in hormone concentrations shows no set pattern with aging in the postmenopausal years.

The significance of locating and filling the canal isthmus in multiple root canal systems. A scanning electron microscopy study of the mesiobuccal root of maxillary first permanent molars

The mesiobuccal (MB) roots of 50 randomly selected maxillary first permanent molars were examined to evaluate the different configurations of canal isthmus and their incidences. Sections of the roots at 3.4, and 5 mm from the apex were prepared, acid etched, washed and dried. The apical side of each section was sputter coated with gold, examined by a Hitachi S-2500 scanning electron microscope and photographed. 36% of the mesiobuccal roots had one canal, whereas 64% had two canals. In the roots with two canals 31.25% contained either a complete isthmus, or accessory canals between the two main canals 31.25% showed partial isthmus formation. The significance of the different configurations is discussed. Our present findings indicate that the mesiobuccal roots of maxillary first permanent molars exhibit complex anatomy. Prudent judgement is essential in the canal isthmus preparation so that operators must provide meticulous skill and care to the patients.

Assessment of outcome prediction models for localized prostate cancer in patients managed with external beam radiation therapy

A comparison of the ability of all published proposed clinical staging systems to predict time to prostate-specific antigen (PSA) failure after external beam radiation therapy for clinically localized prostate cancer was performed using an independent radiation database. Cox regression multivariable analyses were used to assess the significance of the proposed staging systems to predict time to post-radiation PSA failure in 465 radiation managed patients. Significant staging systems identified using Cox regression were further tested using established comparative estimates to define the most predictive system. Both the Risk Score staging system and the staging system based on the calculated volume of prostate cancer (cV(Ca)) and PSA optimized the prediction of time to post-treatment PSA failure. The cV(Ca)-PSA system, however, provided a more clinically useful stratification of outcome. Many clinical staging systems for prostate cancer have been proposed. A single clinical staging system for patients with localized prostate cancer based on parameters obtained during the routine workup provided a statistically and clinically significant stratification of outcome after external beam radiation therapy.

Assessment of outcome prediction models for patients with localized prostate carcinoma managed with radical prostatectomy or external beam radiation therapy

BACKGROUND

A clinical staging system for localized prostate carcinoma that provides reliable information on which management decisions regarding an individual patient can be based is lacking. This study compared the abilities of all published proposed clinical staging systems to predict time to prostate specific antigen (PSA) failure after radical prostatectomy or external beam radiation therapy for clinically localized prostate carcinoma.

METHODS

A total of 1441 clinically localized prostate carcinoma patients who were managed with radical prostatectomy at the University of Pennsylvania in Philadelphia (n = 688) or the Brigham and Women's Hospital in Boston (n = 288) or with external beam radiation therapy at the Joint Center for Radiation Therapy in Boston (n = 465) were entered into this study. Patients who received adjuvant or neoadjuvant hormonal or radiation therapy were excluded. Akaike's Information Criterion (AIC) and Schwartz Bayesian Criterion (SBC) estimates, which are comparative measures, were calculated for each clinical staging system. Pairwise comparisons of the AIC and SBC estimates for the most predictive clinical staging systems were performed using a formal bootstrap technique with 2000 replications.

RESULTS

Both the staging system based on the risk score and the staging system based on the calculated volume of prostate carcinoma and PSA (cVCa-PSA) optimized the prediction of time to posttreatment PSA failure. The cVCa-PSA system, however, provided a more clinically useful stratification of outcome.

CONCLUSIONS

Improved clinical staging for patients with localized prostate carcinoma may be possible with parameters obtained during routine evaluation. Validation by other investigators is underway.

HIV seroprevalence among male prison inmates in the Wisconsin Correctional System

OBJECTIVE

To estimate HIV seroprevalence and the acceptance of voluntary HIV testing among male inmates entering the Wisconsin Correctional System during July 1, 1994-June 30, 1995, and compare these estimates with similar data obtained in 1987-1988.

METHODS

A blinded HIV seroprevalence survey concurrent with a review of voluntary HIV antibody testing records.

RESULTS

HIV test results were obtained for 3,681 (89%) male prison entrants during the study period; 26 (0.7%) were HIV-1 seropositive. Based on this estimate and the total number of male prison entrants (4,134), an estimated 29 HIV-1 seropositive male inmates entered the Wisconsin Correctional System during the study period. Eighty-four percent of all inmates were tested voluntarily. Among inmates testing HIV-1 seropositive, 69% were tested voluntarily.

CONCLUSIONS

These data suggest that HIV-1 seroprevalence among male prison inmates in Wisconsin is low, and is unchanged from the late 1980s; however, a large increase in the prison population has resulted in a substantial increase in the absolute number of HIV-1 seropositive inmates entering the correctional system. Although overall acceptance of voluntary HIV testing is high, nearly one third of HIV-1 seropositive inmates declined voluntary HIV testing.

Immunoperoxidase staining in the differential diagnosis of parathyroid from thyroid origin in fine needle aspirates of suspected parathyroid lesions

OBJECTIVE

To determine whether immunoperoxidase staining could be used for differential diagnosis of parathyroid from thyroid origin in fine needle aspirates of suspected parathyroid lesions.

STUDY DESIGN

Immunoperoxidase staining of parathyroid hormone and thyroglobulin was performed on aspirated smears from 10 patients with parathyroid lesions (6 of 10 patients also associated with thyroid lesions) and 10 patients with thyroid lesions. All of them had surgical tissue proof of the diagnosis.

RESULTS

Aspirated smears of six patients with parathyroid lesions had strong to moderate staining for parathyroid hormone and negative staining for thyroglobulin. Another four patients with parathyroid lesions had equivocal staining for parathyroid hormone and negative staining for thyroglobulin. All aspirated smears from the 16 thyroid lesions had negative staining for parathyroid hormone and positive staining for thyroglobulin.

CONCLUSION

Immunoperoxidase staining of parathyroid hormone and thyroglobulin, done for each suspected parathyroid lesion, was helpful in the differential diagnosis of parathyroid vs. thyroid origin.

Prenatal diagnosis of de novo isochromosome 13q associated with microcephaly, alobar holoprosencephaly and cebocephaly in a fetus

We report on the prenatal diagnosis, genetic studies, and pathology of a case with de novo isochromosome 13q. A 31-year-old primigravida was referred for genetic counselling at 26 weeks' gestation due to the sonographic findings of intrauterine growth retardation and microcephaly. Level II ultrasonograms further demonstrated alobar holoprosencephaly, hypotelorism, polydactyly, a ventricular septal defect, and a single nostril. A diagnosis of cebocephaly was made. Genetic amniocentesis and cord blood sampling revealed translocation trisomy 13 with a de novo t(13q13q) rearrangement. Chromosomal analysis using G- and C-banding techniques and fluorescence in situ hybridization (FISH) showed an apparent monocentric isochromosome. Molecular analyses using polymorphic molecular markers showed that the rearrangement was consistent with an isochromosome of maternal chromosome 13q[46,XX,i(13)(q10)]. Necropsy confirmed cebocephaly and the prenatally detected anomalies.

On the ultrastructure of softened cartilage: a possible model for structural transformation

The fibrillar architecture in the general matrix of softened cartilage has been compared with that of the normal matrix using both Nomarski light microscopy and transmission electron microscopy with combined stereoscopic reconstruction. A pseudorandom network developed from an overall radial arrangement of collagen fibrils is the most fundamental ultrastructural characteristic of the normal general matrix. This, in turn, provides an efficient entrapment system for the swelling proteoglycans. Conversely, the most distinctive feature of the softened matrix is the presence of parallel and relatively unentwined fibrils, strongly aligned in the radial direction. The presence of an optically resolvable fibrous texture in the softened cartilage matrix indicates the presence of discrete bundles of closely packed and aligned fibrils at the ultrastructural level of organisation. The general absence of such texture in the normal cartilage general matrix is consistent with the much greater degree of interconnectedness and related short-range obliquity in the fibrillar architecture, hence the importance of the term pseudorandom network. A mechanism of structural transformation is proposed based on the important property of lateral interconnectivity in the fibrils which involves both entwinement and nonentwinement based interactions. The previously reported difference in intrinsic mechanical strength between the normal and softened matrices is consistent with the transformation model proposed in this study.

A low rate of reinfection following effective therapy against Helicobacter pylori in a developing nation (China)

BACKGROUND & AIMS

In developed countries, reinfection after successful eradication of Helicobacter pylori appears unusual. High prevalences of H. pylori in developing countries may result in high reinfection rates. The aim of this study was to determine the rate of reinfection and ulcer recurrence in Chinese patients cured of H. pylori and duodenal ulcer disease.

METHODS

One hundred eighty-four patients with duodenal ulcer disease shown by endoscopic examination (1 month) and 14C-urea breath test (3 months) after termination of treatment to have cleared their H. pylori were investigated. Patients were followed up by endoscopy (12 and 24 months) and breath test (6, 9, 12, 18, and 24 months). H. pylori status at endoscopic examination was determined by rapid urease, histology, and culture. In reinfected patients, random amplification of polymorphic DNA fingerprinting was used to compare isolates before and after therapy.

RESULTS

Four patients were reinfected with H. pylori over 24 months (3 within 6 months and 1 at 24 months; average annual recurrence rate, 1.08%). Fingerprinting of isolates from 3 patients showed 1 patient (6 months) to have identical strains and the remainder to have nonidentical strains before and after treatment. Ulcer relapse occurred in 6 patients (4 H. pylori positive).

CONCLUSIONS

Reinfection with H. pylori is rare in developing countries where treatment is effective.

Laparoscopically assisted abdominal aortic aneurysm repair: first 20 cases

PURPOSE

Laparoscopic surgery decreases postoperative pain, shortens hospital stay, and returns patients to full functional status more quickly than open surgery for a variety of surgical procedures. This study was undertaken to evaluate laparoscopic techniques for application to abdominal aortic aneurysm (AAA) repair.

METHODS

Twenty patients who had AAAs that required a tube graft underwent laparoscopically assisted AAA repair. The procedure consisted of transperitoneal laparoscopic dissection of the aneurysm neck and iliac vessels. A standard endoaneurysmorrhaphy was then performed through a minilaparotomy using the port sites for the aortic and iliac clamps. Data included operative times, duration of nasogastric suction, intensive care unit days, and postoperative hospital days. Pulmonary artery catheters and transesophageal echocardiography were used in seven patients. For these patients data included heart rate, pulmonary artery systolic and diastolic pressures, mean arterial pressure, central venous pressure, pulmonary capillary wedge pressure, cardiac index, and end diastolic area. Data were obtained before induction, during and after insufflation, during aortic cross-clamp, and at the end of the procedure.

RESULTS

Laparoscopically assisted AAA repair was completed in 18 of 20 patients. Laparoscopic and total operative times were 1.44 +/- 0.44 and 4.1 +/- 0.92 hours, respectively. Duration of nasogastric suction was 1.3 +/- 0.7 days. Intensive care unit stay was 2.2 +/- 0.9 days. The mean length of hospital stay was 5.8 days excluding three patients who underwent other procedures. There were two minor complications, one major complication (colectomy after colon ischemia), and no deaths. For the eight patients who had intraoperative transesophageal echocardiographic monitoring, no changes were noted in heart rate, pulmonary artery systolic pressure, pulmonary capillary wedge pressure, and cardiac index. Pulmonary artery diastolic pressure and central venous pressure were greatest during insufflation without changes in end-diastolic area. Volume status, as reflected by end-diastolic area and pulmonary capillary wedge pressure, did not change.

CONCLUSIONS

Laparoscopically assisted AAA repair is technically challenging but feasible. Potential advantages may be early removal of nasogastric suction, shorter intensive care unit and hospital stays, and prompt return to full functional status. The hemodynamic data obtained from the pulmonary artery catheter and transesophageal echocardiogram during pneumoperitoneum suggest that transesophageal echocardiography may be sufficient for evaluation of volume status along with the added benefit of detection of regional wall motion abnormalities and aortic insufficiency. Further refinement in technique and instrumentation will make total laparoscopic AAA repair a reality.

[Decrease of cAMP and increase of amino acids contents in mouse brain after dihydroetorphine tolerance]

AIM

To study the mechanism of dihydroetorphine (DHE) tolerance.

METHODS

DHE tolerance was produced by repeated s.c. injections in progressively increased doses to mice for 8 d. The concentrations of amino acids and cAMP were detected by RP-HPLC/fluorescence assay and radioimmunoassay, respectively.

RESULTS

The basal contents of glutamic acid (Glu), aspartic acid (Asp), and GABA in whole brain (cerebellum removed) were increased respectively from 14.1 +/- 2.1, 3.0 +/- 0.4, and 1.8 +/- 0.8 mumol/g tissue in control mice to 17.2 +/- 2.2, 4.1 +/- 0.6, and 3.2 +/- 1.0 mumol/g tissue in tolerant mice, and the rates of increase were 22.0% (P < 0.05), 36.7% (P < 0.01), and 77.8% (P < 0.05 vs control), respectively. There was no significant difference in the basal contents of Gln (5.1 +/- 1.0 vs 4.5 +/- 1.7 mumol/g tissue of control). The basal contents of cAMP in hypothalamus and striatum were decreased respectively from 271 +/- 38 and 189 +/- 31 nmol/g tissue in control mice to 96 +/- 15 and 65 +/- 21 nmol/g tissue in tolerant mice (P < 0.01), and the rates of decrease were 64.6% and 65.6%, respectively. There was no significant difference of cAMP in cerebral cortex (72 +/- 20 vs 55 +/- 15 nmol/g tissue of control).

CONCLUSION

The increases of Glu, Asp, and GABA in brain and the decrease of cAMP in hypothalamus and striatum were involved in DHE tolerance.

Demonstration of the distal end of the oesophagus by transabdominal ultrasound

This study aimed to demonstrate the distal end of the oesophagus using a transabdominal ultrasound technique (TUS) and to measure the normal oesophageal wall thickness in adults. 65 patients without oesophageal disease and 38 normal volunteers were examined by TUS. A left subcostal approach was used to demonstrate the oesophagus. The wall thickness and length were measured in both the supine and 45 degrees right side up oblique (RUO) positions. The abdominal oesophagus was visualized in 80% of patients in the supine position and 92% in the RUO position. Satisfactory demonstration was obtained in 67% of patients in the supine and 85% in the RUO position. The oesophageal wall thickness averaged 2.8 mm (range 2.0-4.0 mm, SD 0.7 mm). The visualized length in these subjects averaged 2.3 cm in the supine position and 3.0 cm in the RUO position, which included approximately 1.5 cm of the lowest portion of the thoracic oesophagus in addition to the abdominal oesophagus. TUS can demonstrate the abdominal oesophagus in the majority of patients and has the potential to provide information on disorders of structure and motility.

Impact of respiratory maneuvers on cardiac volume within left-breast radiation portals

BACKGROUND

Late cardiac morbidity and mortality have been reported among left-breast cancer survivors treated with radiation therapy. Radiation-induced cardiotoxicity is affected by the volume of myocardium included in the radiation portals. We hypothesize that simple respiratory maneuvers may alter the position of the heart relative to the portals without altering the radiation dose delivered to the breast.

METHODS AND RESULTS

Fourteen healthy female adult volunteers underwent cardiac MRI to determine the cardiac volume included in the typical left-breast radiation field during respiratory maneuvers. Cardiac volume within the radiation portals was assessed from a transverse stack of 14 1-cm-thick contiguous slices covering the entire heart, obtained during breath holding at end-tidal volume (baseline), deep inspiration, and forced expiration. Thirteen subjects (92%) had inclusion of a portion of the heart within the radiation portals at end-tidal volume (median, 20.9 cm3; range, 1.3 to 88.4 cm3). In these subjects, inspiration decreased the cardiac volume included within the radiation portals (median change: -10.7 cm3 [-40.2%], P<.001 versus end-tidal volume), whereas expiration increased the cardiac volume included (median change: 4.0 cm3 [21.5%]; P<.001 versus end-tidal volume).

CONCLUSIONS

Inclusion of a portion of the heart in the left-breast radiation field is common. The use of simple inspiratory maneuvers significantly decreases cardiac volume within the radiation portals. Such an approach during delivery of radiation therapy may allow for preservation of radiation dosage to the breast while reducing cardiac involvement and subsequent mortality.

Temperature programming and gradient elution in reversed-phase chromatography with packed capillary columns

The two major anisocratic elution modes were compared in reversed-phase chromatography with 180 microns I.D. fused-silica capillary columns packed with 6 microns Zorbax SB ODS-silica. By evaluating the retention factors of alkylbenzenes at acetonitrile concentrations varying from 60 to 80% (v/v) in the aqueous eluent and in the temperature range of 30-80 degrees C, it was found that a 5 degrees C change in column temperature and a 1% change in acetonitrile concentration have almost the same effect on retention. This is illustrated by the almost identical chromatograms of an alkylbenzene sample obtained by temperature programming and by gradient elution under the same conditions otherwise and by simulation of the trajectories of the eluent peaks moving down the column. The results suggest that in reversed-phase HPLC with packed capillary columns temperature programming offers an alternative to gradient elution in a relatively narrow range of the required elution strength. Thermodynamic data from isocratic chromatographic measurements were used to predict the retention times of alkylbenzenes in reversed-phase chromatography with temperature programming at different heating rates and column inlet pressures. Temperature programming was used to separate beta-lactoglobulins A and B by reversed-phase chromatography. It was also employed concomitantly with gradient elution to enhance the separation of a mixture of four standard proteins. The results indicate that temperature programming could serve as an adjunct to gradient elution by means of fine retention tuning to bring about or increase the resolution of closely related macromolecules.

Antecedent hypertension confers increased risk for adverse outcomes after initial myocardial infarction

Several studies have examined the association of blood pressure (BP) after myocardial infarction (MI) with a risk for adverse outcome; however, few studies have investigated prognosis after MI as a function of BP before MI. Our goal was to examine the relation of antecedent hypertension to risk of adverse outcomes after initial MI. From 1967 to 1990, 404 subjects followed at the Framingham Heart Study developed an initial MI. These subjects were classified on the basis of preinfarction BP into normotensive (BP<140/90 mm Hg and not receiving antihypertensive treatment; n=118), stage I-untreated hypertension (BP 140 to 159/90 to 99 mm Hg; n=89), and stage II to IV or treated hypertension (BP > or =160/100 mm Hg or treated hypertension; n=197). Cox models were used to adjust for age, sex, smoking, glucose intolerance, total cholesterol, and prior cardiovascular disease. Antecedent hypertension was related to risk of adverse outcome after MI. Compared with normotensive individuals, stage II to IV hypertensives were at increased risk for reinfarction (hazard ratio [HR], 2.20; 95% confidence interval [CI], 1.20 to 4.04). A similar but nonsignificant association was seen in stage I hypertensives (HR, 1.91; 95% CI, 0.97 to 3.77). Stage II to IV hypertensives were at increased risk for all-cause mortality compared with normotensive persons (HR, 1.45; 95% CI, 1.07 to 1.98). Thus, even after MI, a history of antecedent hypertension remains predictive of adverse outcome. These findings are consistent with beneficial effects of BP control in primary and secondary prevention settings. Effective BP control may both reduce the risk for an initial MI and improve outcome in the event that an MI occurs.

Utility of transesophageal echocardiography and pulmonary artery catheterization during laparoscopic assisted abdominal aortic aneurysm repair

BACKGROUND

Advanced laparoscopic procedures are more commonly performed in elderly patients with cardiac disease. There has been limited data on the use of pulmonary artery catheters (PAC) and transesophageal echocardiography (TEE) to monitor hemodynamic changes.

METHODS

We prospectively studied eight patients undergoing laparoscopic assisted abdominal aortic aneurysm repair. All patients had a PAC and all but one had an intraoperative TEE. Data included heart rate (HR), temperature (temp), pulmonary artery systolic (PAS) and diastolic (PAD) pressures, mean arterial pressure (MAP), central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP), cardiac index (CI), mixed venous oxygen saturation (MVO2), and oxygen extraction ratio (O2Ex) and was obtained prior to induction, during insufflation, after desufflation, during aortic cross-clamp, and at the end of the procedure. End diastolic area (EDA), a reflection of volume status, was measured on TEE. ANOVA was used for data analysis.

RESULTS

No changes were noted in HR, temp, PAS, PCWP, CI, MVO2, and O2Ex. PAD and CVP were greater during insufflation compared with baseline and aortic cross-clamp without associated changes in EDA. MAP was higher at baseline compared with all other times during the procedure.

CONCLUSIONS

Insufflation increased PAD and CVP. However, volume status as suggested by EDA and PCWP did not change. These data question the reliability of hemodynamic measurements obtained from the PAC during pneumoperitoneum and suggest that TEE may be sufficient for evaluation of volume status along with the added benefit of timely detection of ventricular wall motion abnormalities.

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.