"Stark" reality: self-referral rule holds risk and opportunity.

On January 4, 2001, the Health Care Financing Administration (now the Center for Medicare and Medicaid Services or CMS) issued Phase I of the final Stark II regulations (Final Rule). The Final Rule implements the Ethics in Patient Referral Act of 1989 (Stark I), as amended by the Omnibus Budget and Reconciliation Act of 1993 (Stark II), collectively the Stark Law. It is intended to provide more flexibility to providers by interpreting the prohibitions narrowly and the exceptions broadly. Generally, the Stark Law prohibits physicians from referring Medicare or Medicaid patients to an entity for the provision of "designated health services (DHS)" if the physician (or a member of the physician's immediate family) has a direct or indirect financial relationship with the entity. The Final Rule establishes two principal exceptions to the referral prohibition that apply to both ownership/investment interests and compensation arrangements. The physician service exception permits referrals for DHS that are furnished by a member or physician in the same group practice as the referring physician, or under their supervision. The in-office ancillary services exception permits referral for provision of DHS in the same building in which the referring physician or his group routinely provides the full range of the group's or physician's medical services. The final regulations redefine the prior description of radiology and radiation therapy services subject to Stark II. The principal change is to segregate radiation therapy and supplies from radiology and other imaging services. It is uncertain whether Stark Law enforcement will be a priority under the Bush Administration. Nonetheless, because the Final Rule offers more flexibility than the proposed rule, providers and suppliers should revisit proposed and abandoned arrangements that they believed to be prohibited.

Scheduling a delay between different surgeons' cases in the same operating room on the same day using upper prediction bounds for case durations.

UNLABELLED: At some surgical suites, elective cases are only scheduled if they can be completed during regularly scheduled hours. At such a surgical suite, a surgeon may be scheduled to perform one or more cases in an operating room (OR), to be followed by another surgeon who will perform one or more cases. Scheduling a delay between the two surgeons' cases will improve the likelihood that the second surgeon's case(s) will start on time. We show that the mathematics of calculating a scheduled delay between the different surgeons' cases in the same OR on the same day is that of calculating an upper prediction bound for the duration of the second surgeon's case(s). We test an analytical expression for the upper prediction bound for the last one case of the day in an OR, and a Monte Carlo simulation method for the last two cases. We show that these 90% upper prediction bounds are at least as long as the actual durations for 90% +/- 0.2% of single cases and 92% +/- 0.6% of pairs of cases. We conclude that our methodology can be used to calculate an appropriate, and reasonably accurate, scheduled delay between two surgeons' cases in the same OR on the same day. IMPLICATIONS: We show how to use a statistical analysis of historical case duration data to calculate an appropriate and accurate scheduled delay between two surgeons' cases in the same operating room on the same day.

Elevation of alpha2(I) collagen, a suppressor of Ras transformation, is required for stable phenotypic reversion by farnesyltransferase inhibitors.

Farnesyltransferase inhibitors (FTIs) are a novel class of anticancer drugs that can reverse Ras transformation. One of the intriguing aspects of FTI biology is that continuous drug exposure is not necessary to maintain phenotypic reversion. For example, after a single exposure to FTIs, Ha-Ras-transformed fibroblasts revert to a flat and anchorage-dependent phenotype that persists for many days after processed Ras has returned to pretreatment levels. In this study, we show that persistence of the reverted state is mediated by elevated expression of the collagen isoform alpha2(I), a suppressor of Ras transformation the transcription of which is repressed by activated Ras and derepressed by FTI treatment. To our knowledge, this is the first report identifying an FTI-regulated gene which is linked to phenotypic reversion. The finding that extracellular matrix alterations can influence the kinetics of reversion supports our assertion that Rho-regulated cell adhesion parameters are a crucial determinant of the cellular response to FTIs.

Cell growth inhibition by farnesyltransferase inhibitors is mediated by gain of geranylgeranylated RhoB.

Recent results have shown that the ability of farnesyltransferase inhibitors (FTIs) to inhibit malignant cell transformation and Ras prenylation can be separated. We proposed previously that farnesylated Rho proteins are important targets for alternation by FTIs, based on studies of RhoB (the FTI-Rho hypothesis). Cells treated with FTIs exhibit a loss of farnesylated RhoB but a gain of geranylgeranylated RhoB (RhoB-GG), which is associated with loss of growth-promoting activity. In this study, we tested whether the gain of RhoB-GG elicited by FTI treatment was sufficient to mediate FTI-induced cell growth inhibition. In support of this hypothesis, when expressed in Ras-transformed cells RhoB-GG induced phenotypic reversion, cell growth inhibition, and activation of the cell cycle kinase inhibitor p21WAF1. RhoB-GG did not affect the phenotype or growth of normal cells. These effects were similar to FTI treatment insofar as they were all induced in transformed cells but not in normal cells. RhoB-GG did not promote anoikis of Ras-transformed cells, implying that this response to FTIs involves loss-of-function effects. Our findings corroborate the FTI-Rho hypothesis and demonstrate that gain-of-function effects on Rho are part of the drug mechanism. Gain of RhoB-GG may explain how FTIs inhibit the growth of human tumor cells that lack Ras mutations.

Functional interaction between RhoB and the transcription factor DB1.

RhoB has been implicated in cell growth control, actin regulation, adhesion-dependent viability, and gene expression, but its effector functions are poorly defined. Prenylation is important for the physiological functions of Rho proteins, so to identify RhoB effector functions we identified proteins whose interaction was sensitive to prenylation. Here we report the investigation of one such protein, an ubiquitously expressed transcription factor termed DB1 that was originally cloned as a Tax-activated regulator of the IL3 promoter. The RhoB-binding domain in DB1 was located in a functionally undefined region upstream and separable from its zinc finger DNA binding domain. DB1 interacted strongly with prenylated RhoB but weakly with RhoA and not at all with H-Ras. Functional interaction was supported by the identification of prenylated species of RhoB in the nuclear membrane and in an intranuclear laminar region, where they were available for DB1 association in principle, and by the ability of RhoB to inhibit transcriptional activation by DB1, whereas RhoA or Ras had little or no effect, respectively. The results of this study suggest a novel mechanism by which certain Rho proteins may regulate transcription, through sequestration of a transcription factor.

Non-Ras targets of farnesyltransferase inhibitors: focus on Rho.

Farnesyltransferase inhibitors (FTIs) are a novel class of cancer therapeutics whose development was based on the discovery that the function of oncogenic Ras depends upon its posttranslational farnesylation. Significantly, experiments in animal models have shown that FTIs have promise as nontoxic cancer therapeutics. However, cell biological studies have suggested that FTIs may act at a level beyond that of suppressing Ras function, so the exact mechanism of action has emerged as a question of major interest. Here, we review evidence that proteins other than Ras are important targets for inhibition, summarize findings suggesting a role for farnesylated Rho proteins prompted by studies on RhoB, and suggest a new model for how FTIs exert their biological effects. The 'FTI-Rho hypothesis' proposes that FTIs act in part by altering Rho-dependent cell adhesion signals which are linked to pathways controlling cell cycle and cell survival and which are subverted or defective in neoplastic cells. This model offers a novel framework for addressing the questions about FTI biology, including the basis for lack of toxicity to normal cells, cytotoxic versus cytostatic effects on tumor cells, and the persistence and drug resistance of malignant cells in FTI-treated animals.

Physician unionization.

Typically, doctors have seemed unsuited for and uncomfortable with the idea of unions but with the current changes in practices and referral patterns, doctors are looking--at least warily--at unions. Two sets of laws apply to possible unionization of physicians; one, federal antitrust laws, the other, both federal and state labor laws as they apply to changes in the medical profession. Antitrust laws are designed to protect competition by prohibiting price fixing. Another typical antitrust issue that applies to healthcare is that of a group boycott or refusal to deal, where competitors try to coerce a third party to set prices where competitors want them set. Congress' earliest legislation to aide the labor movement involved exceptions to the antitrust laws. Some provisions of the laws are limited to workers who are employees, defined as someone who is employed by any person. Doctors are searching for solutions that provide the collective power of the labor laws without offending the antitrust laws. The question is whether doctors can form unions under these two conflicting forces. The first main issue is whether the doctor is or is not an employee. Although radiologic technologists, typically employees of hospitals or provider groups, have been unionized for years, doctors are usually not employees, at least not if they have their own practices. Although not employees, physicians may affiliate with a larger union to use that broader bargaining power, a purpose that is permissible under current law. Membership in a union does have its responsibilities and disadvantages. Some have suggested that the definition of employee be broadened to cover physician duties under managed care payer agreements, for example. Meanwhile, the Federal Trade Commission and the Justice Department are watching that non-employee physicians not use the union label to mask price fixing, boycotts or refusals to deal.

Farnesyltransferase inhibitors alter the prenylation and growth-stimulating function of RhoB.

Protein farnesyltransferase inhibitors (FTIs) inhibit Ras transformation and Ras-dependent tumor cell growth, but the biological mechanisms underlying these activities is unclear. In previous work, we presented support for the hypothesis that the anti-transforming effects of FTIs depend upon alterations in the function of RhoB, a member of the Rho family of proteins that regulate cytoskeletal actin, cell adhesion, and cell growth. A significant question that needed to be addressed was whether FTIs could directly alter the prenylation as well as the function of RhoB in cells. This issue is complex because farnesylated and geranylgeranylated forms of RhoB (RhoB-F and RhoB-GG) both exist in cells. Here, we show that RhoB farnesylation in vitro can be catalyzed by protein farnesyltransferase and that the peptidomimetic FTI L-739,749 inhibits the farnesylation of RhoB both in vitro and in intact cells. In drug-treated cells, the level of RhoB-GG increased in parallel with the decrease in RhoB-F. In addition to altering RhoB prenylation, L-739,749 suppressed RhoB-dependent cell growth. Taken together, the results suggest that the inhibitory effects of FTIs on RhoB function can be mediated by a relative loss of RhoB-F, a gain of RhoB-GG, or both. Our findings strengthen the causal link between RhoB inhibition and the anti-transforming effects of FTIs and indicate that differently prenylated forms of RhoB may have unique functions.

Prenylation of RhoB is required for its cell transforming function but not its ability to activate serum response element-dependent transcription.

Rho regulates cytoskeletal actin structure and integrin-mediated cell adhesion. Rho also has a role in cell growth regulation and is required for cell transformation by oncogenic Ras. Recently, it has been demonstrated that Rho can activate transcription from the c-fos serum response element (SRE). This raised the possibility that functions required for Rho-mediated cell transformation might overlap with those involved in transcriptional regulation. Here we show that RhoB can activate the SRE and can synergize in cell transformation with constitutively activated Raf-CAAX. Significantly, unprenylated forms of RhoB that are biologically inert and unable to transform cells can still activate SRE-dependent transcription. This finding suggests that transcriptional activation by Rho may be separable from its cell transforming functions.

Farnesyl transferase inhibitors induce apoptosis of Ras-transformed cells denied substratum attachment.

Farnesyl transferase inhibitors (FTIs) are a novel class of antitumor drugs that block the oncogenic activity of Ras. Because FTIs lack significant cell toxicity in vitro and in vivo, a significant question is how they cause tumor regression. We now report that FTIs are in fact potent activators of apoptosis in Ras-transformed cells if attachment to substratum is prevented. When cultured at high density or on polyHEMA, a nonadherent substrate, Ras-transformed cells exhibited massive DNA degradation and cell death within 24 h of treatment with the FTI L-739,749. Death was p53-independent and was inhibited by the apoptosis suppressor BCL-XL. Furthermore, apoptosis was significantly attenuated by ectopic expression of a farnesyl-independent form of RhoB, a Rho protein previously implicated as a critical target for inhibition by FTIs. The findings suggest a link between FTIs and Rho-dependent adhesion signaling. Furthermore, our work indicates that FTIs revert cells to a state in which cell-substratum attachment is necessary for viability and suggests that apoptosis forms the basis for drug-induced tumor regression.

Resistance of a variant ras-transformed cell line to phenotypic reversion by farnesyl transferase inhibitors.

Pharmacological inhibitors of the housekeeping enzyme farnesyl transferase (FT) inhibit the growth of ras-transformed cells in vitro and in vivo without antiproliferative effects on normal cells. In one direction to analyze the basis for this selectivity and to study modes of drug resistance that arise in animals, we characterized a variant ras-transformed cell line, 749r-1, which was resistant to phenotypic reversion with FT inhibitors. The transformed phenotype, growth potential, and actin cytoskeleton of 749r-1 cells were unaffected by treatment with the FT inhibitor 1-739,749 at concentrations up to 30-fold higher than those sufficient to revert ras-transformed cells. Resistance correlated with a reduced ability of L-739,749 to inhibit the farnesylation of Ras and lamin B and with a reduction in the susceptibility of endogenous FT to drug inhibition. These effects were not due to mutation of the FT subunits, changes in intracellular drug accumulation, or amplification of the multiple drug resistance gene (MDR). However, a similar reduction in the ability of L-739,749 to inhibit Ras farnesylation was also seen in ras-transformed cells rendered resistant by ectopic expression of farnesyl-independent RhoB, suggesting some mechanistic overlap. We concluded that 749r-1 cells sustained a stable alteration that conferred drug resistance by a novel mechanism.

Trimethaphan versus sodium nitroprusside for the control of proximal hypertension during thoracic aortic cross-clamping: the effects on spinal cord ischemia.

Sodium nitroprusside (SNP) has been used to control the proximal hypertension associated with thoracic aortic cross-clamping (TACC) during thoracic aortic surgery. It worsens neurologic outcome, presumably by further decreasing distal arterial pressure and increasing cerebrospinal fluid (CSF) pressure, thereby worsening the spinal cord perfusion pressure (SCPP). Trimethaphan does not increase CSF pressure. Therefore, the present study investigates the effect of trimethaphan versus SNP to control proximal hypertension during TACC on neurologic outcome. Two groups, each with eight mongrel dogs, were studied. All animals underwent descending TACC for 45 min. The mean proximal aortic blood pressure was maintained at 95-100 mm Hg by the use of SNP or trimethaphan. Distal aortic pressure was allowed to vary. The dogs were neurologically evaluated 24 and 48 h later by a blinded observer. During cross-clamping, there was no difference in mean proximal aortic pressure between groups. After 10 min of cross-clamping, distal aortic pressure was higher (P < 0.01), CSF pressure was lower (P < 0.01), and SCPP was higher (P < 0.005) in the trimethaphan group as compared with the SNP group (group effect). Neurologic outcome as assessed by Tarlov's score was better at 24 and 48 h in the trimethaphan group (P < 0.05). Histopathologic injury trended with worsened neurologic outcome. We conclude that 1) trimethaphan produced higher SCPP than SNP, and 2) neurologic outcome was better in the trimethaphan group.

Evidence that farnesyltransferase inhibitors suppress Ras transformation by interfering with Rho activity.

Small-molecule inhibitors of the housekeeping enzyme farnesyltransferase (FT) suppress the malignant growth of Ras-transformed cells. Previous work suggested that the activity of these compounds reflected effects on actin stress fiber regulation rather than Ras inhibition. Rho proteins regulate stress fiber formation, and one member of this family, RhoB, is farnesylated in vivo. Therefore, we tested the hypothesis that interference with RhoB was the principal basis by which the peptidomimetic FT inhibitor L-739,749 suppressed Ras transformation. The half-life of RhoB was found to be approximately 2 h, supporting the possibility that it could be functionally depleted within the 18-h period required by L-739,749 to induce reversion. Cell treatment with L-739,749 disrupted the vesicular localization of RhoB but did not effect the localization of the closely related RhoA protein. Ras-transformed Rat1 cells ectopically expressing N-myristylated forms of RhoB (Myr-rhoB), whose vesicular localization was unaffected by L-739,749, were resistant to drug treatment. The protective effect of Myr-rhoB required the integrity of the RhoB effector domain and was not due to a gain-of-function effect of myristylation on cell growth. In contrast, Rat1 cells transformed by a myristylated Ras construct remained susceptible to growth inhibition by L-739,749. We concluded that Rho is necessary for Ras transformation and that FT inhibitors suppress the transformed phenotype at least in part by direct or indirect interference with Rho, possibly with RhoB itself.

Critical role of Rho in cell transformation by oncogenic Ras.

We demonstrate that Rho, a regulator of cytoskeletal actin, is necessary for Ras transformation. A dominant inhibitory Rho gene (RhoBN19) specifically suppressed Rat1 cell focus formation induced by oncogenic Ras but not by Raf. An activated Rho gene (RhoBV14) lacked focus formation activity but augmented the focus formation activity of both oncogenes. NIH3T3 cell lines expressing RhoBV14 grew to higher saturation density and displayed reduced serum and anchorage requirements for growth. We concluded that Rho played a role in cell growth regulation and was required for transformation by oncogenic Ras but not Raf. A model for Ras signal transduction proposing separate Rho-dependent and Raf-dependent pathways is discussed.

An audit of adverse events in children sedated with chloral hydrate or propofol during imaging studies.

We examined records of sedations provided by the paediatric anaesthesiology staff for 455 children (ages 1 mo-17 yr) undergoing MRI or CT scans at our institution over a twelve-month period with regard to the monitoring of adverse events: excessive sedation, agitation, vomiting, hypoxaemia, and major airway compromise. One hundred-and-thirty-one patients (29%) received chloral hydrate; 324 patients (71%) received propofol. All patients were monitored with continuous noninvasive pulse oximetry and received supplemental oxygen via nasal cannulae. Of the patients who received chloral hydrate, 64 (49%) were over one year of age; of the patients who received propofol, 318 (98%) were one year of age or older. In the chloral hydrate group, 23 patients (19%) were deemed excessively sedated and four patients (3%) were agitated; no patients in the propofol group experienced any of the adverse outcomes reviewed. Furthermore, no patients in either group had significant airway compromise and none was admitted to the hospital as a result of the sedation.

Propofol reduces the incidence of vomiting after tonsillectomy in children.

We compared the effect of a propofol-based anaesthetic to an isoflurane-based anaesthetic on the incidence of postoperative vomiting in children following tonsillectomy. Thirty-nine children were enrolled in the study and randomized to receive one of the proposed anaesthetics. All patients underwent a mask induction with halothane, nitrous oxide, and oxygen. Intravenous access was established and all children received fentanyl (2-4 micrograms.kg-1) i.v., mivacurium (0.3 mg.kg-1) i.v. and acetaminophen (10-15 mg.kg-1) p.r. Following tracheal intubation, patients received either isoflurane (0.8-1.6%) or propofol (120-180 micrograms.kg-1 min-1) i.v. with nitrous oxide 70%/oxygen 30% for maintenance of anaesthesia. Vital signs were maintained within 20% of baseline. All patients were extubated in the operating room. PACU nursing staff recorded episodes of vomiting for 4-6 h prior to discharge. A telephone interview the following day was also used for data recovery. Age, sex, and duration of the procedure were not significantly different between the two study groups. Of 19 patients who received propofol, four vomited (21%); in contrast, of the 20 patients who received isoflurane, 11 vomited (55%). This difference is significant (P = 0.048 two-tailed Fisher's Exact Test). These data suggest that using propofol for anaesthesia can diminish the incidence of vomiting following tonsillectomy.

Delayed awakening from general anaesthesia in a patient with Hunter syndrome.

Hunter syndrome is one of a heterogeneous group of recessively inherited mucopolysaccharide storage diseases (MPS) with similar biochemical defects manifested by impairments in mucopolysaccharide catabolism with variable but progressive clinical courses. Abnormal accumulation and deposition of mucopolysaccharides in the tissue of several organs to numerous anatomical, musculoskeletal and neurological abnormalities which are known to complicate anaesthetic and airway management. Hunter syndrome has a wide variance of clinical phenotypes ranging from mild to severe. We present a patient having physical and neurological features consistent with a severe clinical presentation of Hunter syndrome (MPS, Type II). Following a seemingly uneventful intraoperative anaesthetic course including isoflurane, nitrous oxide and fentanyl (0.93 microgram.kg-1), resumption of spontaneous ventilation and return to consciousness were delayed until intravenous naloxone (200 micrograms) was administered 110 min after the opioid administration. The cause of delayed recovery from anaesthesia in this patient is unknown.