Effect of Health Care Financing Administration regulation on radiology fellowship training

RATIONALE AND OBJECTIVES

The purpose of this study was to assess the effect of Health Care Financing Administration (HCFA) regulations on radiology fellowship training.

MATERIALS AND METHODS

Surveys were sent to 157 fellowship program directors in body imaging and vascular/ interventional radiology. Questions addressed program accreditation status, faculty supervision of fellows, and any change in faculty supervision of fellows in response to HCFA's revised plan for Medicare Part B reimbursement.

RESULTS

Eighty of 157 (51%) surveys were returned. Thirty (37%) respondents indicated supervision of fellows had changed after institution of the new HCFA rules in July 1996. Vascular/interventional program directors (n = 25, 49%) were more likely to have changed their practice than body imaging program directors (n = 5, 17%). Nearly all respondents (29 of 30, 97%) indicating a change stated supervision had increased. Twenty-seven (33%) respondents also indicated faculty supervision was beyond that necessary for patient care and house staff education; most of these respondents (21 of 27, 78%) stated the new HCFA regulations were responsible. Many program directors also expressed concern the HCFA regulations might prevent fellows from obtaining sufficient experience to effectively learn independent clinical decision-making.

CONCLUSION

HCFA regulations intended to address attending physician billing practices at teaching institutions may have had the unintended effect of substantively altering the training of radiology fellows.

Systolic dysfunction of the ventricle in congestive heart failure: pathophysiology, diagnosis, and therapy

Investigations into the pathophysiology and treatment of the failing left ventricle have yielded impressive results over the past three decades. Patients with systolic dysfunction have abnormalities of the molecular machinery and signaling of contraction which may be in-born or acquired, and result in the characteristic mechanical abnormalities associated with this condition. Correlation of these ultrastructural contractile abnormalities with the mechanical dysfunction observed clinically is complicated by alterations of preload and afterload which accompany systolic failure. The systemic consequences of contractile failure result in a cascade of neuroendocrine and cytokine activation which perpetuates a cycle of further myocardial dysfunction and systemic humoral response. Based on this neuroendocrine paradigm, pharmacologic intervention trials have yielded promising gains in survival and symptom status in patients with systolic dysfunction, particularly with the ACE inhibitors and the beta-adrenergic blockers. For patients with acute systolic failure the inotropic agents continue to be useful in short term support but chronic administration with these agents should be avoided because of enhanced mortality observed in virtually all placebo controlled trials. Finally, long-term mortality rates remain high in patients with systolic dysfunction despite current therapy, thus offering an opportunity for the novel approaches currently under investigation to substantially impact on patient outcomes. (c)1999 by CHF, Inc.

Reconstruction for lower limb occlusive disease in the elderly

OBJECTIVES

To determine the acceptability of performing distal limb bypass for occlusive vascular disease in the over 75's.

METHOD

Patients undergoing surgery between January 1988 and December 1996 were included. Data were obtained from a card system, operating ledgers, admission diaries and hospital notes.

RESULTS

A total of 166 patients were identified. There were 69 women and 97 men, 79 were aged 75-79 years, 81 were 80-89 years and six older than 90 years. A total of 171 procedures were performed: infrainguinal bypass in 131 (77%), aorto-femoral bifurcation grafts in 10 (6%) and extra-anatomic bypass in 30 (17%). This represents 28.1% of all reconstructions for occlusive disease during this time. Nine patients (5.4%) died within 30 days and one (0.6%) required a major amputation. During the follow-up period (median 12 months), 14 major and 10 minor amputations were required. Ten patients underwent a second successful reconstructive procedure.

CONCLUSION

Reconstruction in this group of older patients can be carried out with acceptable 30-day mortality and limb salvage rates.

Survival of Listeria monocytogenes in sea water and effect of exposure on thermal resistance

Survival, recoverability and sublethal injury of two strains of Listeria monocytogenes, Scott A and an environmental strain KM, on exposure to sea water at 12.8 or 20.8 degrees C was determined using in situ diffusion chambers. Plate counts were used to assess recoverability and injury while 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) reduction was used to determine respiratory activity. T90 values (times for 10-fold decreases in numbers of recoverable cells) on non-selective medium (trypticase soya agar with 0.6% yeast extract) at 12.8 and 20.8 degrees C were 61.7 and 69.2 h for L. monocytogenes Scott A, and 103.0 and 67.0 h for L. monocytogenes KM, respectively. On selective medium (Oxford agar), T90 values at 12.8 and 20.8 degrees C were 60.6 and 56.9 h for L. monocytogenes Scott A, and 83.0 and 65.9 h for L. monocytogenes KM, respectively. With Scott A, the percentage of sublethally injured cells at 12.8 and 20.8 degrees C was 1.7 and 17.7%, respectively, while for KM the values were 19.0 and 1.6%, respectively. The fraction of cells reducing CTC but which were not recoverable on plating progressively increased on exposure to sea water. Listeria monocytogenes KM challenged at 58 degrees C showed an apparent increase in heat resistance after exposure to sea water at 20.8 degrees C for 7 d (D58 = 2.64 min) compared with before exposure (D58 = 1.24). This increase in thermal resistance was not apparent at temperatures greater than 63 degrees C, and analysis of the best-fit regression lines fitted to the thermal data obtained from the two cell populations indicated that their thermal resistance was not significantly different (P > 0.05) over the temperature range tested (58-62 degrees C).

Loss of CFTR chloride channels alters salt absorption by cystic fibrosis airway epithelia in vitro

Cystic fibrosis (CF) is caused by the loss of functional CFTR Cl- channels. However, it is not understood how this defect disrupts salt and liquid movement in the airway or whether it alters the NaCl concentration in the thin liquid film covering the airway surface. Using a new approach, we found that CF airway surface liquid had a higher NaCl concentration than normal. Both CF and non-CF epithelia absorbed salt and liquid; however, expression of CFTR Cl- channels was required for maximal absorption. Thus, loss of CFTR elevates the salt concentration in CF airway surface liquid and in sweat by related mechanisms; the elevated NaCl concentration is due to a block in transcellular Cl- movement. The high NaCl may predispose CF airways to bacterial infections by inhibiting endogenous antibacterial defenses.

Pex20p of the yeast Yarrowia lipolytica is required for the oligomerization of thiolase in the cytosol and for its targeting to the peroxisome

Pex mutants are defective in peroxisome assembly. In the pex20-1 mutant strain of the yeast Yarrowia lipolytica, the peroxisomal matrix protein thiolase is mislocalized exclusively to the cytosol, whereas the import of other peroxisomal proteins is unaffected. The PEX20 gene was isolated by functional complementation of the pex20-1 strain and encodes a protein, Pex20p, of 424 amino acids (47,274 D). Despite its role in the peroxisomal import of thiolase, which is targeted by an amino-terminal peroxisomal targeting signal-2 (PTS2), Pex20p does not exhibit homology to Pex7p, which acts as the PTS2 receptor. Pex20p is mostly cytosolic, whereas 4-8% is associated with high-speed (200,000 g) pelletable peroxisomes. In the wild-type strain, all newly synthesized thiolase is associated with Pex20p in a heterotetrameric complex composed of two polypeptide chains of each protein. This association is independent of PTS2. Pex20p is required for both the oligomerization of thiolase in the cytosol and its targeting to the peroxisome. Our data suggest that monomeric Pex20p binds newly synthesized monomeric thiolase in the cytosol and promotes the formation of a heterotetrameric complex of these two proteins, which could further bind to the peroxisomal membrane. Translocation of the thiolase homodimer into the peroxisomal matrix would release Pex20p monomers back to the cytosol, thereby permitting a new cycle of binding-oligomerization-targeting-release for Pex20p and thiolase.

Apoptosis induction by caspase-8 is amplified through the mitochondrial release of cytochrome c

Apoptosis often involves the release of cytochrome c from mitochondria, leading to caspase activation. However, in apoptosis mediated by CD95 (Fas/APO-1), caspase-8 (FLICE/MACH/Mch5) is immediately activated and, in principle, could process other caspases directly. To investigate whether caspase-8 could also act through mitochondria, we added active caspase-8 to a Xenopus cell-free system requiring these organelles. Caspase-8 rapidly promoted the apoptotic program, culminating in fragmentation of chromatin and the nuclear membrane. In extracts devoid of mitochondria, caspase-8 produced DNA degradation, but left nuclear membranes intact. Thus, mitochondria were required for complete engagement of the apoptotic machinery. In the absence of mitochondria, high concentrations of caspase-8 were required to activate downstream caspases. However, when mitochondria were present, the effects of low concentrations of caspase-8 were vastly amplified through cytochrome c-dependent caspase activation. Caspase-8 promoted cytochrome c release indirectly, by cleaving at least one cytosolic substrate. Bcl-2 blocked apoptosis only at the lowest caspase-8 concentrations, potentially explaining why CD95-induced apoptosis can often evade inhibition by Bcl-2.

Divergent effects of angiotensin-converting enzyme inhibition and angiotensin II-receptor antagonism on myocardial cellular proliferation and collagen deposition after myocardial infarction in rats

There is mechanistic rationale to suggest differential effects of angiotensin-converting enzyme (ACE) inhibition and angiotensin II type 1 (AT1)-receptor antagonism on ventricular remodeling after myocardial infarction (MI). We compared the effects of ACE inhibition, AT1-receptor antagonism, and their combination on post-MI ventricular remodeling in rats. We induced MI in 62 rats, which then received one of four treatments: (a) placebo; (b) the ACE inhibitor, enalapril; (c) the AT1-receptor antagonist, losartan; and (d) enalapril and losartan in combination. Two weeks after MI, we examined: (a) heart weight (HW)/body weight (BW) ratio; (b) nonmyocyte cellular proliferation in the noninfarct zone by using proliferating cell nuclear antigen staining; and (c) collagen content within the noninfarct zone. Placebo-treated, infarcted rats developed significant increases in HW/BW ratio (p < 0.001), left ventricular (LV) volume (p < 0.01), nonmyocyte cellular proliferation (p < 0.04), and collagen content (p < 0.01) compared with noninfarcted controls. Enalapril, losartan, and combination therapy limited the increase in HW/BW ratio (all p values <0.01 vs. placebo). Enalapril inhibited nonmyocyte proliferation (p < 0.01 vs. placebo), whereas losartan had a smaller effect (p = NS vs. placebo; p < 0.03 vs. enalapril); combined treatment also reduced nonmyocyte cellular proliferation but did not reach statistical significance (p = 0.08 vs. placebo). Enalapril and combination treatment significantly diminished collagen content (both p values <0.01 vs. placebo), whereas losartan did not. Thus, ACE inhibition and AT1-receptor antagonism equally limited myocardial hypertrophy after MI in rats, but ACE inhibition more effectively prevented nonmyocyte cellular proliferation and collagen deposition in the noninfarcted myocardium. Combination therapy was no more effective than was ACE inhibition alone. These data suggest that the myocyte hypertrophic response after MI is strongly influenced by activation of the AT1 receptor, whereas nonmyocyte cellular proliferation and collagen deposition result, in part, from mechanisms separate from AT1-receptor activation.

Ventricular remodeling in a mouse model of myocardial infarction

We investigated the suitability of studying ventricular remodeling in a mouse model of myocardial infarction (MI). We performed left coronary ligation (n = 22) or a sham procedure (n = 21) on normal C57BL/6J mice. Six weeks later, animals underwent echocardiography and hemodynamic evaluation. Left ventricular (LV) volume at a common distending pressure was calculated from passive pressure-volume curves. The MI group exhibited lower systolic blood pressure (P < 0.05), higher LV end-diastolic pressure (P < 0.05), and lower peak first derivative of LV pressure (dP/dt, P < 0.05) than the sham group. Mice with moderate (< 40%, n = 11) and large (> or = 40%, n = 11) MIs displayed increased LV mass-to-body weight ratio (P < 0.02 and P < 0.01, respectively, vs. sham group), whereas only the large-MI group exhibited increased right ventricular mass-to-body weight ratio (P < 0.01). LV volumes were increased in the moderate-MI group (P = 0.059 vs. sham group) and to a much greater extent in the large-MI group (P < 0.0001 vs. sham group). The moderate- and large-MI groups also exhibited increases in LV end-diastolic diameter (P < 0.03 and P < 0.0001, respectively, vs. sham group) and LV end-systolic diameter (P < 0.01 and P < 0.0001, respectively, vs. sham group) with decreased fractional shortening (P < 0.01 for both). These data demonstrate ventricular remodeling in a mouse model of MI and confirm the feasibility of quantifying indexes of remodeling in vivo and postmortem. This model will be of particular usefulness when applied to transgenic strains.

Warfarin anticoagulation and survival: a cohort analysis from the Studies of Left Ventricular Dysfunction

OBJECTIVES

We sought to evaluate the relation between warfarin anticoagulation and survival and morbidity from cardiac disease in patients with left ventricular (LV) dysfunction.

BACKGROUND

Warfarin anticoagulation plays a major role in the management of patients who have had a large myocardial infarction and in those with atrial fibrillation. However, its use in patients with LV systolic dysfunction has been controversial.

METHODS

We reviewed data on warfarin use in 6,797 patients enrolled in the Studies of Left Ventricular Dysfunction (SOLVD) trial and analyzed the relation between warfarin use and all-cause mortality, as well as the combined end point of death or hospital admission for heart failure. We used Cox regression to adjust for differences in baseline characteristics and to test for the interaction between warfarin use and selected patient variables in relation to outcome.

RESULTS

On multivariate analysis, use of warfarin was associated with a significant reduction in all-cause mortality (adjusted hazard ratio [HR] 0.76, 95% confidence interval [CI] 0.65 to 0.89, p = 0.0006) and in the risk of death or hospital admission for heart failure (HR 0.82, 95% CI 0.72 to 0.93, p = 0.0002). Risk reduction was observed when each trial or randomization arm was analyzed separately, as well as in both genders. It was not significantly influenced by the presence of atrial fibrillation, age, ejection fraction, New York Heart Association functional class or etiology.

CONCLUSIONS

In patients with LV systolic dysfunction, warfarin use is associated with improved survival and reduced morbidity. This association is primarily due to a reduction in cardiac events and does not appear to be limited to any particular subgroup.

Endoscopic injection of glutaraldehyde cross-linked collagen for efferent limb incompetence in the Indiana reservoir

PURPOSE

We determined the clinical applicability, safety and efficacy of endoscopically injected glutaraldehyde cross-linked collagen for the treatment of efferent limb incompetence in the incontinent Indiana urinary reservoir.

MATERIALS AND METHODS

Six patients were diagnosed with incompetence of the efferent limb of the Indiana reservoir by video urodynamics. Glutaraldehyde cross-linked collagen was injected through the efferent limb at the level of the ileocecal valve. Outcome was assessed by evaluation of dryness and pouchograms.

RESULTS

With a mean followup time of 26 months (range 6 to 36) after the last injection 5 of the 6 patients were cured. The remaining patient, although improved, had a small capacity and subsequently underwent ileal patch augmentation. No patient failed to improve. The mean volume of collagen was 16 ml. (range, 5 to 26). Reservoir volume increased from 150 to 400 ml.

CONCLUSIONS

The use of glutaraldehyde cross-linked collagen in the treatment of the incontinent Indiana reservoir is safe and effective.

Transcoronary ethanol ablation of the atrioventricular node in a young patient with tricuspid atresia

Catheter ablation of AV conduction with radiofrequency energy can be challenging in the presence of structural abnormalities of the AV junction, either congenitally or after reconstructive surgery. We used transcoronary ethanol to ablate the AV node in a patient with classic tricuspid atresia and refractory intraatrial reentry tachycardia. This approach provides an alternative means of creating complete heart block with catheter-based techniques, when radiofrequency catheter ablation is technically impossible or ineffective.

Subfascial endoscopic perforator vein surgery (SEPS): current practice among British surgeons

Subfascial endoscopic perforator vein surgery (SEPS) has recently caused considerable interest among British surgeons. There are no data indicating which, if any, patients benefit from SEPS. A series of 47 British surgeons, identified as having taken up SEPS, were sent a questionnaire asking about their current practice; 26 were returned completed (55% response rate). Of those surgeons replying, 22 (85%) had performed their first SEPS procedure within the previous 21 months, 18 (69%) within the previous 9 months. Most surgeons had performed five procedures (range 1-52). The most common indication for SEPS was venous ulceration with proven incompetent perforators (eight surgeons), but there was a wide diversity of other indications used to select patients for SEPS. Only nine surgeons had changed their indications for surgery with the advent of SEPS, yet their predicted number of SEPS procedures was far greater than the number of open procedures they currently performed. Out of 26 surgeons, 25 intend to continue performing SEPS. Prospective studies are needed to identify which patients might benefit from this new procedure.

In vivo effects of dexmedetomidine on laser-Doppler flow and pial arteriolar diameter

BACKGROUND

The alpha2-adrenergic agonist dexmedetomidine alters global cerebral blood flow (CBF). However, few studies have investigated the action of dexmedetomidine on the cerebral microcirculation. This investigation examined the effects of dexmedetomidine on (1) regional CBF in the rat cerebral cortex using laser-Doppler flowmetry and (2) on pial arteriolar diameter.

METHODS

Halothane-anesthetized rats were fitted with instruments to measure CBF as determined by laser-Doppler flow (CBFldf) or to measure pial arteriolar diameter by preparing a cranial hollow deepened until a translucent plate of skull remained, thereby maintaining the integrity of the cranial vault. In both groups, 20 microg/kg dexmedetomidine was infused intravenously. Thirty minutes later, the mean arterial pressure was restored to control values with an infusion of phenylephrine (0.5 to 5 microg/kg/min).

RESULTS

Administration of dexmedetomidine was associated with decreases in end-tidal and arterial carbon dioxide. The CBFldf and pial arteriolar diameter were measured during normocapnia (controlled carbon dioxide) and during dexmedetomidine-induced hypocapnia. Intravenous administration of dexmedetomidine significantly decreased systemic arterial pressure concurrent with a decrease in CBFldf (22% in normocapnic animals, 36% in hypocapnic animals). Restoration of mean arterial pressure increased CBFldf in normocapnic but not in hypocapnic animals. Similarly, dexmedetomidine significantly reduced pial vessel diameter in both normocapnic (9%) and hypocapnic animals (17%). However, vessel diameters remained decreased in the normocapnic and hypocapnic animals after the mean arterial pressure was restored.

CONCLUSIONS

These results suggest a modulation of cerebral vascular autoregulation by dexmedetomidine which may be mediated, in part, by alterations in carbon dioxide. Dexmedetomidine may have a direct action on the cerebral vessels to reduce the CBF during normo- or hypocapnia. The differences between CBFldf and pial arteriole responses to restoration of mean arterial pressure may reflect the difference in measurement techniques because laser-Doppler measurements reflect the net effect of several arterial segments on microvascular perfusion, whereas diameter measurements specifically examined individual pial arterioles, suggesting that dexmedetomidine vasoconstriction in the cerebral vasculature may be differentially and regionally mediated.

Antiplatelet agents and survival: a cohort analysis from the Studies of Left Ventricular Dysfunction (SOLVD) trial

OBJECTIVES

This study sought to evaluate the relation between antiplatelet agent (APA) use and survival and morbidity from cardiac disease in patients with left ventricular (LV) systolic dysfunction.

BACKGROUND

APAs play an important role in the prevention and treatment of coronary disease. Their effects in patients with LV systolic dysfunction are unknown.

METHODS

We reviewed data on APA use in 6,797 patients enrolled in the Studies of Left Ventricular Dysfunction (SOLVD) trial and analyzed the relation between their use and all-cause mortality as well as the combined end point of death or hospital admission for heart failure (HF). We used Cox regression to adjust for differences in baseline characteristics and to test for the interaction between APA use and selected patient variables in relation to outcome.

RESULTS

APA use (46.3% of patients) was associated with significantly reduced mortality from all causes (adjusted hazard ratio [HR] 0.82, 95% confidence interval [CI] 0.73 to 0.92, p = 0.0005) and reduced risk of death or hospital admission for HF (adjusted HR 0.81, 95% CI 0.74 to 0.89, p < 0.0001) but was not influenced by trial assignment, gender, LV ejection fraction, New York Heart Association class or etiology. A strong interaction was observed among APA use, randomization group and all-cause mortality. The association between APA use and survival was not observed in the enalapril group, nor was an enalapril benefit on survival detectable in patients receiving APAs at baseline. However, randomization to enalapril therapy significantly reduced the combined end point of death or hospital admission for HF in APA users.

CONCLUSIONS

In patients with LV systolic dysfunction, use of APAs is associated with improved survival and reduced morbidity. This association is retained after adjustment for baseline characteristics. APA use is associated with retained but reduced benefit from enalapril.

Reaper-induced apoptosis in a vertebrate system

The reaper protein of Drosophila melanogaster has been shown to be a central regulator of apoptosis in that organism. However, it has not been shown to function in any vertebrate nor have the cellular components required for its action been defined. In this report we show that reaper can induce rapid apoptosis in vitro using an apoptotic reconstitution system derived from Xenopus eggs. Moreover, we show that a subcellular fraction enriched in mitochondria is required for this process and that reaper, acting in conjunction with cytosolic factors, can trigger mitochondrial cytochrome c release. Bcl-2 antagonizes these effects, but high levels of reaper can overcome the Bcl-2 block. These results demonstrate that reaper can function in a vertebrate context, suggesting that reaper-responsive factors are conserved elements of the apoptotic program.

Augmentation cystoplasty

The past 15 years have been witness to an explosion in the number of reconstructive procedures using bowel in the urinary tract. As with many concepts in medicine, one must rely on clinical experience while laboratory models and other advancements develop. This article attempts to address bladder reconstruction by enterocystoplasty, as well as the indications for augmentation, types of procedures available, and the early and late complications.

Conservative surgery for ureteral tumor associated with horseshoe kidney

PURPOSE

We demonstrate the successful conservative management of a ureteral tumor in a horseshoe kidney.

MATERIALS AND METHODS

A patient with low grade transitional cell carcinoma of the left lower ureter had asymptomatic horseshoe kidney. Biopsy specimen revealed low grade tumor in the lower urinary tract that was associated with a congenital abnormality. The patient underwent total ureterectomy with bladder cuff excision and ileal ureteral interposition.

RESULTS

With this technique renal function was preserved without resection through the isthmus of the kidney. The patient has no evidence of recurrent disease after 20-month followup by cytology, computerized tomography, excretory urogram and cystoscopy.

CONCLUSIONS

Organ preserving surgery is an alternative to total nephroureterectomy in lower ureteral tumors in select patients.

Ileal ureter

Ureteral replacement with ileal bowel segments has become common in the armamentarium of the reconstructive urologist. The use of ileal bowel substitution, whether total or segmental, has provided yet another surgical alternative for renal preservation. The indications, surgical technique, and results with the ileal ureter are reviewed.

In vivo forces during remodeling of a two-segment anterior cruciate ligament graft in a goat model

An existing goat model was used to measure in vivo graft forces during walking, to determine if the forces set at surgery change over time under the same external load and if the forces in the graft during in vivo function can be dictated by the forces set at surgery. The anterior cruciate ligament was reconstructed in 12 goats with use of a composite graft consisting of a bone-patellar tendon-bone autograft and a synthetic augmentation segment. The forces in the graft segments were established intraoperatively by a force-setting technique. In five animals, the tendon segment was set to carry 90% of the total graft force, and in the seven other animals, the augmentation segment was set to carry 90% of the total force. The total graft force was the same in all animals. Graft forces due to anterior tibial loads of 67 N were measured before and after fixation and 6 weeks after surgery with the use of buckle transducers mounted extra-articularly over the anterior tibia. They were also measured during straight, level walking at 6 weeks. The forces changed significantly from just after surgery to 6 weeks later, such that the initially set load-sharing was eliminated by 6 weeks. At 6 weeks, a relatively smooth gait had been achieved, and the maximum total graft force in each animal during walking averaged 35 N and was of similar magnitude to forces generated by the anterior tibial loads of 67 N with the animal anesthetized. After fixation, forces in the tendon graft segments were significantly different between the group with high set forces and that with low set forces. At 6 weeks, when functional joint loads were approaching normal levels, the graft segment forces for the two groups were not significantly different. Load-sharing between tendon and augmentation segment and load in the tendon segment at 6 weeks could not be dictated at surgery.