Nanosecond laser therapy reverses pathologic and molecular changes in age-related macular degeneration without retinal damage.

Age-related macular degeneration (AMD) is a leading cause of vision loss, characterized by drusen deposits and thickened Bruch's membrane (BM). This study details the capacity of nanosecond laser treatment to reduce drusen and thin BM while maintaining retinal structure. Fifty patients with AMD had a single nanosecond laser treatment session and after 2 yr, change in drusen area was compared with an untreated cohort of patients. The retinal effect of the laser was determined in human and mouse eyes using immunohistochemistry and compared with untreated eyes. In a mouse with thickened BM (ApoEnull), the effect of laser treatment was quantified using electron microscopy and quantitative PCR. In patients with AMD, nanosecond laser treatment reduced drusen load at 2 yr. Retinal structure was not compromised in human and mouse retina after laser treatment, with only a discrete retinal pigment epithelium (RPE) injury, and limited mononuclear cell response observed. BM was thinned in the ApoEnull mouse 3 mo after treatment (ApoEnull treated 683 ± 38 nm, ApoEnull untreated 890 ± 60 nm, C57Bl6J 606 ± 43 nm), with the expression of matrix metalloproteinase-2 and -3 increased (>260%). Nanosecond laser resolved drusen independent of retinal damage and improved BM structure, suggesting this treatment has the potential to reduce AMD progression.

Intragenic recombination in an E beta gene for a murine Ia antigen.

The recombinant strain D2.GD was originally typed as I-Ad by serological methods. Indeed, the A alpha and A beta chains of the I-A antigens appear to exhibit normal behavior by the criteria of serology and two dimensional gel analysis. However, the E beta chain encoded by the I-A subregion of this strain, one of the two components of the plasma membrane located I-E antigens produced in D2.GD X A.TFR5)F1 animals, has been demonstrated to be the product of an intragenic recombinational event between E beta genes from the d and b haplotypes. Sequence analysis suggests that the amino-terminal portion of the Eg2 beta chain is derived from the d haplotype and, therefore, that the coding strand for this gene is oriented centromeric leads to telomeric (5' to 3' direction). Finally, these data combined with the data of Rose and Cullen (17) allow the ordering of the genes within the I-A subregion as (H-2K), A alpha, A beta, E beta ... (H-2D).

Rosetting of activated human T lymphocytes with autologous erythrocytes. Definition of the receptor and ligand molecules as CD2 and lymphocyte function-associated antigen 3 (LFA-3).

CD2, also known as LFA-2, T11, and the E rosette receptor, is a T lymphocyte surface protein functionally important in adhesion to target cells and T cell triggering. LFA-3 is a widely distributed cell surface protein that functions in adhesion on target cells. We find that LFA-3 is expressed on human E, and that CD2 is a receptor for LFA-3 that mediates T cell adhesion to human E. Pretreatment of T lymphocytes with CD2 mAb or of E with LFA-3 mAb inhibits rosetting. Purified CD2 molecules bind to human E and inhibit rosetting. 125I-CD2 binding to E is inhibited by LFA-3 mAb; reciprocally, binding of LFA-3 mAb to human E is inhibited by pretreatment with purified CD2. Higher concentrations of CD2 aggregate human E; aggregation is inhibited by mAb to LFA-3.

A quantitative in vivo mouse model used to assay inhibitors of tumor-induced angiogenesis.

An in vivo model of tumor-induced angiogenesis was used to monitor two known inhibitors of angiogenesis, protamine sulfate and the steroid tetrahydro S. Tumor cells entrapped in alginate beads were injected s.c. into mice. Blood vessel induction was measured by two quantitative methods: measurement of hemoglobin at the alginate pellet site, and pooling of radiolabeled RBC to the alginate pellet site. The two methods gave parallel results. Tetrahydro S with or without heparin inhibited blood vessel growth by 50%, and protamine sulfate inhibited blood vessel growth by 85%. These results were supported by gross morphology and histological analysis of the alginate pellet site.

Analysis of prostate and seminal vesicle motion: implications for treatment planning.

PURPOSE: To quantify prostate and seminal vesicle positional changes (target motion) between treatment planning and delivery, and to identify the factors contributing to target motion. METHODS AND MATERIALS: Thirty patients with adenocarcinoma of the prostate were prospectively evaluated by analyzing two sequential planning computerized tomography (CT) scans (S1, obtained prior to treatment, and S2, obtained during the fourth week of treatment) for each patient. All anatomical volumes of interest (soft tissue and bony) were reconstructed from transverse CT images and projected onto anterior and lateral beam's-eye view projections. Positional changes between S1 and S2 were eliminated by applying a rigid body translation and rotation. Target motion was then measured by recording the positional change between S1 and S2 at the edges (right, left, superior, inferior). Potential correlation of target motion with bladder volume, rectal volume, and rectal diameter changes were evaluated by linear regression analysis. RESULTS: Neither the prostate nor seminal vesicles remained fixed with respect to bony anatomy between S1 and S2. The distribution of positional changes were generally small (< 0.5 cm), but maximum displacements of 1.5-2.2 cm did occur, particularly in the lateral view. In this study, bladder volume changes between the scans were small and did not correlate with target motion (P = 0.67). Both rectal volume and rectal diameter changes correlated with target motion for both the prostate (p = 0.004 and 0.005, respectively) and seminal vesicles (p < 0.001 and < 0.001, respectively). However, neither the initial rectal volume nor the initial rectal diameter could be used to predict subsequent target motion when evaluated either singly or as part of a multiple regression model. CONCLUSIONS: Target motion occurs during the course of treatment planning and delivery and should be considered when designing conformal radiation fields. Although the target position at the time of planning CT may differ substantially from the mean treatment position, target motion cannot be predicted by evaluating simply measured parameters from a single scan, or double scan sequence.

Conformal prostate brachytherapy: initial experience of a phase I/II dose-escalating trial.

PURPOSE: To improve treatment results on prostatic adenocarcinoma, conformal radiation therapy (CRT) has been used. Two major drawbacks of external CRT are: (a) internal organ motion/daily set-up variations, and (b) exclusion of several patients for CRT based on poor geometrical relationships as identified by three dimensional (3D) treatment planning. To overcome the above problems, we began the first prospective Phase I/II dose-escalating clinical trial of conformal brachytherapy (CB) and concurrent external beam irradiation. METHODS AND MATERIALS: Fifty-nine patients with T2b-T3c prostatic adenocarcinoma received 176 transperineal ultrasound-guided conformal high-dose rate (HDR) boost implants. All patients received concomitant external beam pelvic irradiation. Dose escalation of the three HDR-CB fractions proceeded as follows: 5.5 Gy (30 patients), 6 Gy (20 patients), and 6.5 Gy (9 patients). The CB dose was prescribed to the prostate contour as outlined using an online biplanar transrectal ultrasound probe. The urethra, anterior rectal wall, and prostate boundaries were identified individually and outlined at 5 mm intervals from the base to the apex of the gland. The CB using real-time ultrasound guidance with interactive online isodose distributions was performed on an outpatient basis. As needles were placed into the prostate, corrections for prostate displacement were recorded and the isodose distributions were recalculated to represent the new relationship between the needles, prostate, and normal structures. No computerized tomography (CT) planning or implant preplanning was required. RESULTS: No patient was rejected based on poor geometrical relation of pelvic structures. In every implant performed, prostate displacement was noted. Craniocaudal motion of the gland ranged from 0.5-2.0 cm (mean = 1.0 cm), whereas lateral displacement was 0.1-0.4 cm. With the interactive online planning system, organ motion was immediately detected, accounted for, and corrected prior to each HDR treatment. The rectal dose has ranged from 45 to 87%, and the urethral dose from 97 to 112% of the prostate dose. It is significant to note that operator dependence has been completely removed because the interactive online planning system uniformly guides the physicians. CONCLUSIONS: With ultrasound guidance and the interactive online dosimetry system, organ motion (as compared to external beam) is insignificant because it can be corrected during the procedure without increasing target volume margins. Common pitfalls of brachytherapy, including operator dependence and difficulty with reproducibility, have been eliminated with the intraoperative online planning system.

Evaluation of a clinical scintillation camera with pulse tail extrapolation electronics.

The performance of a new scintillation camera, designed for high event rate capability, was evaluated. The system consisted of a 400 mm field-of-view Nal(T1) camera with 61 photomultiplier tubes and modified General Electric Starport electronics. A significant feature of the system was circuitry for performing pulse tail extrapolation and separation of individual pulses involved in pulse pile-up events. System deadtime, flood field uniformity, energy resolution, linearity, spatial resolution, and bar phantom image quality were evaluated for count rates up to 200 kcps in a 20% photopeak window. Our results indicate that this camera design does not compromise image quality at normal clinical count rates and at higher event rates can provide better image quality and increased sensitivity over many Anger cameras currently employed in nuclear medicine.

Cardiac output responses during exercise in volume-expanded heart transplant recipients.

The mechanisms responsible for immediate adjustments in cardiac output at onset of exercise, in the absence of neural drive, are not well defined in heart transplant (HT) recipients. Seven male HT recipients (mean +/- SD 57 +/- 6 years) and 7 age-matched sedentary normal control subjects (mean age 57 +/- 5 years) performed constant load cycle exercise at 40% of peak power output (Watts). Cardiac output and plasma norepinephrine were determined at rest and every 30 seconds during the first 5 minutes of exercise and at minutes 6, 8, and 10. All subjects were admitted to the General Clinical Research Center for determination of plasma volume. After 3 days of equilibration to a controlled and standardized diet, plasma volume was measured using a modified Evans Blue Dye (T-1824) dilution technique. Heart rate at rest was higher in the HT group (105 +/- 12 vs 74 +/- 6 beats/min), but during submaximum exercise, heart rates in the control group increased more rapidly (p < or = 0.05) and to a greater magnitude (54 +/- 7% vs 17 +/- 4% above rest). Stroke volume at rest was lower in HT recipients (45 +/- 4 vs 68 +/- 9 ml) but was significantly augmented immediately after onset of exercise (30 seconds) and the relative increase was greater than controls at peak exercise (61% vs 38% greater than baseline). Cardiac output at rest was within the normal range in both groups (4.58 +/- 0.27 vs 4.94 +/- 0.40 L/min). Relative increases in cardiac output were similar (p > or = 0.05) for the HT (106 +/- 12%) and control groups (97 +/- 10%). Plasma norepinephrine did not become significantly greater than resting values until approximately 4 minutes after onset of exercise in both groups. Blood volume, normalized for body weight, was 12% greater in the HT group. Thus, HT recipients with expanded blood volume (12%) augment stroke volume immediately after the onset of exercise. Plasma norepinephrine levels contribute negligibly to the rapid adjustment in cardiac output. Rather, we speculate that abrupt on-transit increases in stroke volume are due to augmented venous return, secondary to expanded blood volume.

Chronic hypoxia induces adaptive metabolic changes in neonatal myocardium.

The effect of chronic hypoxia on neonatal myocardial metabolism remains undefined. With a new neonatal piglet model, we determined changes in myocardial metabolism during global ischemia after chronic hypoxia. Five-day-old piglets (N = 30) were randomly assigned to two groups and exposed to an atmosphere of 8% oxygen or to room air for 28 days before they were killed. Left ventricular myocardium was then analyzed at control and at 15-minute intervals during 60 minutes of global normothermic ischemia to determine high-energy phosphate levels, glycogen stores, and lactate accumulation. Time to peak ischemic myocardial contracture was measured with intramyocardial needle-tipped Millar catheters as a marker of the onset of irreversible ischemic injury. Results showed an initially greater level of myocardial adenosine triphosphate in the hypoxic group (27 +/- 1.2 vs 19 +/- 1.8 micromol/gm dry wt, p = 0.001) and a delay in adenosine triphosphate depletion during 60 minutes of global ischemia compared with the control group. Initial energy charge ratios (1/2 adenosine diphosphate + adenosine triphosphate/adenosine monophosphate + adenosine diphosphate + adenosine triphosphate) were also greater in the hypoxic group (0.96 +/- 0.01 vs 0.81 +/- 0.04, p = 0.01) and remained so throughout global ischemia. Initial glycogen stores were greater in the hypoxic group (273 +/- 13.3 vs 215 +/- 14.7 micromol/gm dry weight, p = 0.02) when compared with the control group. Lactate levels in the hypoxic group were initially higher (19.1 +/- 6.4 vs 8.9 +/- 3.1 micromol/gm dry weight, p = 0.001) compared with control levels and remained elevated throughout 60 minutes of ischemia. Time to peak ischemic contracture was prolonged in the hypoxic group (69.5 +/- 1.8 vs 48.9 +/- 1.4 minutes, p = 0.001) compared with the controls group. These data show that chronic hypoxia results in significant myocardial metabolic adaptive changes, which in turn result in an improved tolerance to severe normothermic ischemia. These beneficial effects are associated with elevated baseline glycogen storage levels and an accelerated rate of anaerobic glycolysis during ischemia.

Improved donor myocardial recovery with a new lazaroid lipid antiperoxidant in the isolated canine heart.

U74006F is a new 21-amino steroid (lazaroid) that prevents lipid peroxidation without glucocorticoid or mineralocorticoid side effects. Reperfusion injury has been reduced by the addition of various free radical scavengers and antiperoxidants to the reperfusate. To assess the effect of U74006F on reperfusion of donor hearts subjected to prolonged hypothermic ischemia, 21 isolated canine hearts were divided into three groups: control (group 1), drug (2 mg/kg) injected into the oxygenated blood perfusate immediately before 4 hours of preservation (group 2), and drug (2 mg/kg) injected 1 hour before heart isolation and again 15 minutes before reperfusion (group 3). After control left ventricular function studies (with an intraventricular balloon) and biopsy for high-energy phosphates and dry/wet ratios, the hearts were arrested with cold cardioplegia and cooled for 4 hours then reperfused for 3 hours. Left ventricular work was calculated by systolic and diastolic pressure curves, which showed a better return of function in group 3 hearts (1625, 2150, and 3493 mm Hg/ml in groups 1, 2, and 3, respectively, at 180 minutes of reperfusion; p = 0.02). This was likely the result of improved diastolic compliance in group 3. Dry/wet ratios showed increased tissue edema in all hearts at the end of reperfusion. Although high-energy phosphate concentrations were not different between groups, adenosine was best preserved in group 3 (p = 0.03), suggesting reduced washout of this precursor. In conclusion, administration of U74006F before preservation and reperfusion may be useful for donor heart protection.

Mechanical cardiac actuation achieves hemodynamics similar to cardiopulmonary bypass.

The disadvantages of blood/interface interactions and difficult installation are common to current circulatory support devices. Direct mechanical ventricular actuation (DMVA) is a method of biventricular cardiac massage that avoids contact of blood with various surfaces. The purpose of this study was to compare hemodynamic responses and organ perfusion between DMVA and cardiopulmonary bypass (CPB). Twenty adult mixed-breed dogs randomized for DMVA or CPB were anesthetized with alpha-chloralose. During 4 hours of ventricular fibrillation, animals received either DMVA or CPB with aortic arch perfusion (90 to 120 ml/kg/min), bicaval venous return, and full left ventricle venting. Hemodynamics and organ perfusion were assessed by multivariant analysis of variance with repeated measures. Blood flow was similar to normal sinus rhythm (control) with either method; however, average CPB flows (control, 110%) were increased significantly over DMVA flows (control, 75%) (p = 0.016). The resulting mean arterial pressures were significantly greater during DMVA (control, 66%) compared to CPB (control, 49%) (p = 0.0011). Radiolabeled microspheres were the measure of organ perfusion during sinus rhythm and at 2 and 4 hours of circulatory support. Myocardial blood flow was equal to control in all regions during DMVA; CPB resulted in increased flows to the left ventricular epicardium, septum, and right ventricle. DMVA generated significantly greater flows to the renal cortex. All other organs demonstrated similar perfusion with either method. However, CPB displayed declining cerebral flows at 4 hours compared to DMVA (42% vs 55% control, respectively). Overall, DMVA provided hemodynamic stability equal to that of CPB. Rapid application and avoidance of blood/surface contact make DMVA a favorable method of temporary circulatory support.

Use of the "chimney patch" technique for Norwood stage I procedures.

The Norwood stage I procedure is often used for the initial treatment of infants with hypoplastic left heart syndrome. This procedure creates a systemic arterial to pulmonary artery shunt to establish pulmonary blood flow. We describe a method to facilitate placement of this shunt by attaching a polytetrafluoroethylene shunt to a pulmonary artery homograft patch before performing the median sternotomy. This technique facilitates the performance of the proximal shunt anastomosis and expedites the procedure.

Staged repair of acute type I aortic dissection and coarctation in pregnancy.

A 29-year-old gravid female presented at 22 weeks gestation with an acute Type I aortic dissection and coarctation of the aorta. She underwent emergent repair of her aortic dissection using cardiopulmonary bypass and hypothermia. At 25 weeks gestation, she underwent repair of her coarctation of the aorta. The patient had a cesarean delivery of a viable, normal male infant at 39 weeks gestation.

Argon beam coagulation compared with cryoablation of ventricular subendocardium.

The Argon Beam Coagulator uses radiofrequency energy to excite argon gas that may be used for ventricular ablation. The effects of power level and number of applications of the Argon Beam Coagulator were compared wtih cryothermia. Ten mongrel dogs underwent cardiac extirpation. The endocardial surfaces of 5 hearts were used for the creation of lesions using the Argon Beam Coagulator at five power levels with either one or two applications. Five hearts were used for endocardial and epicardial lesions using cryothermia (15-mm-diameter probe at -70 degrees C) for 1, 2, 3, or 4 minutes. The Argon Beam Coagulator lesions showed an increase in depth with increasing power levels (2.25 +/- 1.05 mm at 50 W to 6.64 +/- 0.75 mm at 150 W) and number of applications (maximum depth of 6.64 +/- 0.75 mm with one application, 11.2 +/- 1.1 mm with two applications). Cryothermia lesions were similar in depth regardless of duration or site of application (range, 6.1 to 10.2 mm). Both techniques resulted in homogeneous and well-demarcated lesions. These data show that the Argon Beam Coagulator results in discrete endocardial lesions, which may be created quickly and reproducibly. This may be a useful alternative for the operative ablation of endocardial scar in the treatment of ventricular tachycardia.

Surgical treatment of automatic atrial tachycardias.

From 1979 to 1989, 18 patients were seen in the Electrophysiology Service, Duke University Medical Center, with automatic atrial tachycardia. There were 8 male and 10 female patients with a mean age of 28.1 +/- 2.9 years. Electrophysiological mapping localized automatic foci to right atrial sites (14 patients) and left atrial sites (4 patients). Depending on origin of the focus, patients were further diagnosed as having either chronic ectopic atrial tachycardia or inappropriate sinus tachycardia. Of the 15 patients with chronic ectopic atrial tachycardia, 6 responded to medical treatment; in 9, the tachycardia was not adequately controlled. Six of them were referred for surgical intervention. All 3 patients with inappropriate sinus tachycardia underwent operative therapy. In the surgical group of patients with chronic ectopic atrial tachycardia, all 6 had a tachycardia-induced cardiomyopathy with ejection fractions ranging from 14% to 27% (mean ejection fraction, 21% +/- 2.7%). Surgical techniques used (alone or in combination) included an isolation procedure in 1 patient, cryoablation in 4 patients, and excision of atrial appendages or portions of atrial free walls in 7. Normal sinus rhythm developed in all surgical patients except 1 patient who had intractable congestive heart failure preoperatively and died of this condition and stroke. The overall success rates for medical and surgical therapy were 33.3% and 88.9%, respectively (p less than 0.01). Long-term follow-up was possible for 7 (87.5%) of 8 patients 3 to 7 years after operation. All patients with chronic ectopic atrial tachycardia were cured, but only 1 of 3 patients with inappropriate sinus tachycardia was in sinus rhythm.(ABSTRACT TRUNCATED AT 250 WORDS)

Homograft replacement of mitral valve in children.

BACKGROUND: Recent reports have demonstrated successful early outcomes using mitral valve homografts in adults. We report our early results after homograft mitral valve replacement in 4 children with previous atrioventricular septal defects, previous placement of a prosthetic valve, and rheumatic valvular disease. METHODS: Between May 1996 and June 1997, 4 children (ages 5, 11, 13, and 15 years) underwent mitral valve replacement with cryopreserved mitral valve homografts at our institution. Preoperative echocardiography confirmed moderately severe to severe mitral regurgitation, stenosis, or both in all 4 patients. RESULTS: Successful homograft valve replacement was achieved in all 4 patients. Based on symptoms, physical examinations, and echocardiographic follow-up, all four homograft mitral valves are functioning well with normal hemodynamics. None of these patients are receiving warfarin. Follow-up has been limited to 10 months. CONCLUSIONS: In children requiring mitral valve replacement, the use of mitral valve homografts offers advantages over prosthetic valves, such as the avoidance of complications associated with thrombosis and anticoagulation. Homograft mitral valve replacement is technically feasible in children with congenital and rheumatic heart disease and previous prosthetic valves.

First successful bridge to cardiac transplantation using direct mechanical ventricular actuation.

Currently available ventricular assist devices are technically difficult to implant, require continuous anticoagulation, and are associated with hemorrhagic and thromboembolic complications. Direct mechanical ventricular actuation is a biventricular assist device that can be applied in 3 to 5 minutes through a left anterior thoracotomy and has no direct blood contact or need for anticoagulation. The present study was designed to determine the effects of direct mechanical ventricular actuation in total biventricular circulatory support. Cardiogenic shock refractory to standard therapy developed in 2 patients awaiting cardiac transplantation. Direct mechanical ventricular actuation was applied and provided immediate hemodynamic stabilization in both. All inotropic agents and intraaortic balloon support were then discontinued. Fifty-six hours of circulatory support bridged the first patient to successful cardiac transplantation without complication. The patient is alive and well more than 1 year later without incident of infection or rejection. The second patient suffered cardiac arrest and required closed chest cardiopulmonary resuscitation before device application. After 45 hours of support, it was determined that irreversible neurologic injury had occurred and direct mechanical ventricular actuation was discontinued. Neither patient's native heart exhibited any histologic evidence of device-related trauma. Direct mechanical ventricular actuation has undergone limited clinical investigation since its original description 25 years ago, but in these initial trials, the device has proved effective. The concept of mechanically actuating the ventricles appears to be a valuable, yet under-utilized method of total circulatory support.

Radiation exposure from conventional and digital subtraction angiography of cerebral vessels.

Patients with atherosclerotic cerebrovascular disease were studied to determine the radiation exposure associated with conventional and digital subtraction angiography of the cerebral vessels. The median exposure-area product was 3198 R cm2 (range, 616-5665 R cm2) in the conventional angiography group and 1831 R cm2 (range, 366-4198 R cm2) in the IV digital subtraction angiography (DSA) group. This difference in exposure resulted from increased use of fluoroscopy in the conventional screen-film angiography group. The actual difference in exposure between the radiographic and digital imaging portions of the examinations was much smaller. The contributions of fluoroscopy to the radiation exposure in conventional angiography and IV-DSA in this study were 37% (range, 8.8-76%) and 6% (range, 1.5-25%), respectively.

Interface of epilepsy and sleep disorders.

Obstructive sleep apnoea was first brought to prominence by Henri Gastaut, a French epileptologist. Since that time the interface between epilepsy and sleep disorders has received less attention than might be justified, recognizing that sleep deprivation is a poignant provocateur for seizures. Sleep deprivation is often used as a diagnostic procedure during electroencephalography (EEG) when waking EEG has failed to demonstrate abnormality. Patients referred to an outpatient neurological clinic for evaluation of possible seizures in whom sleep disorder was suspected, either due to snoring during the EEG or based on history, were evaluated with all-night diagnostic polysomnography (PSG) and appropriate intervention administered as indicated. Patient and seizure demography, sleep disorder and response to therapy were reviewed and the interface explored. Fifty patients aged between 10 and 83 years underwent PSG. Approximately half were diagnosed with epilepsy and almost three-quarters had sleep disorders sufficiently intrusive to require therapy (either continuous positive air pressure (CPAP) or medication). With co-existence of epilepsy and sleep disorders, proper management of sleep disorders provided significant benefit for seizure control. Snoring during EEG recordings could alert to the possibility of a sleep disorder even with epilepsy diagnosed. Where both epilepsy and sleep disorder coexist appropriate management of the sleep disorder improves control of the epilepsy.