Prosecutors and end-of-life decision making

OBJECTIVE

To examine personal beliefs and professional behavior of state criminal prosecutors toward end-of-life decisions.

DESIGN

Mail survey.

SETTING

District attorney offices nationwide.

PARTICIPANTS

All prosecuting attorneys who are members of the National District Attorneys Association. A total of 2844 surveys were mailed with 2 follow-up mailings at 6-week intervals; 761 surveys were returned for a response rate of 26.8%. The majority of respondents were white men, Protestant, and served in rural areas.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

On the basis of 4 case scenarios, (1) professional behavior as determined by respondents' willingness to prosecute and what criminal charges they would seek; and (2) personal beliefs as determined by whether prosecutors believed the physicians' actions were morally wrong and whether they would want the same action taken if they were in the patient's condition.

RESULTS

Most respondents would not seek prosecution in 3 of the 4 cases. In the fourth case, involving physician-assisted suicide, only about one third of the respondents said that they definitely would prosecute. Those who would prosecute would most often seek a charge of criminal homicide. A majority of respondents believed that the physicians' actions were morally correct in each of the 4 cases and would want the same action taken if they were in the patient's position. There was a strong correlation between personal beliefs and professional behaviors.

CONCLUSIONS

A large majority of responding prosecutors were unwilling to prosecute physicians in cases that clearly fall within currently accepted legal and professional boundaries. In the case of physician-assisted suicide, results reflected a surprisingly large professional unwillingness to prosecute and an even greater personal acceptance of physician-assisted suicide.

Regions of endonuclease EcoRII involved in DNA target recognition identified by membrane-bound peptide repertoires

Target sequence-specific DNA binding regions of the restriction endonuclease EcoRII were identified by screening a membrane-bound EcoRII-derived peptide scan with an EcoRII recognition site (CCWGG) oligonucleotide duplex. Dodecapeptides overlapping by nine amino acids and representing the complete protein were prepared by spot synthesis. Two separate DNA binding regions, amino acids 88-102 and amino acids 256-273, which share the consensus motif KXRXXK, emerged. Screening 570 single substitution analogues obtained by exchanging every residue of both binding sites for all other amino acids demonstrated that replacing basic residues in the consensus motifs significantly reduced DNA binding. EcoRII mutant enzymes generated by substituting alanine or glutamic acid for the consensus lysine residues in DNA binding site I expressed attenuated DNA binding, whereas corresponding substitutions in DNA binding site II caused impaired cleavage, but enzyme secondary structure was unaffected. Furthermore, Glu96, which is part of a potential catalytic motif and also locates to DNA binding site I, was demonstrated to be critical for DNA cleavage and binding. Homology studies of DNA binding site II revealed strong local homology to SsoII (recognition sequence, CCNGG) and patterns of sequence conservation, suggesting the existence of functionally related DNA binding sites in diverse restriction endonucleases with recognition sequences containing terminal C:G or G:C pairs.

Induction of hypoxia inducible factor 1 by oxygen glucose deprivation is attenuated by hypoxic preconditioning in rat cultured neurons

Hypoxia-inducible factor 1 (HIF-1) is a posttranscriptionally regulated transcription factor, controlling several hypoxia-inducible genes. Here we show a rapid and transient increase of HIF-1 DNA binding activity in a dose dependent manner in primary cortical neurons of rats exposed to oxygen glucose deprivation (OGD) for 30, 60, 90, or 120 min. A reduced induction of binding activity was observed when neurons were preconditioned by a non-lethal OGD interval (60 min) 48 h prior to the 90 min OGD. Thus, hypoxic preconditioning reduces activation of HIF-1 binding activity. The molecular mechanism of HIF-1 activation, its target genes, and its role in tolerance induction and/or ischemia induced damage remain to be elucidated.

Cooperative binding properties of restriction endonuclease EcoRII with DNA recognition sites

EcoRII is a member of the expanding group of type IIe restriction endonucleases that share the distinguishing feature of requiring cooperativity between two recognition sites in their substrate DNA. To determine the stoichiometry of the active DNA-enzyme complex and the mode of cooperative interaction, we have investigated the dependence of EcoRII cleavage on the concentration of EcoRII dimers. Maximal restriction was observed at dimer/site ratios of 0.25 and 0. 5. The molecular weight of the DNA-enzyme complex eluted from a gel filtration column also corresponds to a dimeric enzyme structure bound to two substrate sites. We conclude that one EcoRII dimer is sufficient to interact cooperatively with two DNA recognition sites. A Lac repressor "barrier" bound between two normally reactive EcoRII sites did not inhibit restriction endonuclease activity, indicating that cooperativity between EcoRII sites is achieved by bending or looping of the intervening DNA stretch. Comparative cleavage of linear substrates with differently spaced interacting sites revealed an inverse correlation between cleavage rate and site distance. At the optimal distance of one helical turn, EcoRII cleavage is independent of the orientation of the recognition sequence in the DNA double strand.

An experimental selection system to identify bacterial cells exhibiting a new DNA host specificity

Restriction-modification enzymes interact with DNA sequences in a highly specific manner. Mutations within the DNA binding region of the enzymes could be expected to produce enzyme variants with changed DNA sequence specificities. We developed an efficient in vivo selection system that enabled us to detect one cell coding for a restriction-modification system with a new DNA sequence specificity in a background of more than 10(6) cells with the original DNA sequence specificity.

Mutual activation of two restriction endonucleases: interaction of EcoP1 and EcoP15

Type III restriction endonucleases recognize nonsymmetric nucleotide sequences. A necessary condition for DNA cleavage is the presence of two unmethylated recognition sites which are inversely ('head-to-head') oriented in the DNA double strand. A DNA substrate possessing one EcoP1 and one EcoP15 site in the head-to-head configuration could not be cleaved by the individual enzymes, however, it was specifically digested in the simultaneous presence of both enzymes. In agreement with the tracking-collision model for the DNA interaction of type III enzymes cleavage could be abolished by Lac repressor bound between the two sites. We conclude that two different type III enzymes can functionally cooperate in the cleavage of DNA.

Induction of tolerance in rat cortical neurons: hypoxic preconditioning

Sublethal ischemia leads to increased tolerance against subsequent prolonged cerebral ischemia in vivo. In the present study we modeled preconditioning mechanisms in a neuronal-enriched culture. Damage was significantly reduced (up to 72%) with 1.5 h of oxygen-glucose deprivation 48-72 h before 3 h oxygen-glucose deprivation. Tolerance was also elicited by Na+-K+-ATPase inhibition. No damage was observed when astroglial or endothelial cells were exposed to hypoxia for 3 and 6 h, respectively. We conclude that hypoxic preconditioning is a robust neuronal phenomenon in vitro with a similar temporal pattern and selective cellular vulnerability as the ischemic tolerance phenomenon shown in vivo.

Legal and ethical myths about informed consent

Informed consent is a foundational concept of medical ethics. Since its enunciation almost 4 decades ago, it has engendered, and continues to engender, a great deal of debate and opposition from practicing physicians. We believe that much of the negative reaction to informed consent stems from some fundamental misunderstandings about what informed consent requires. This article discusses and refutes several myths about informed consent that have acquired some currency among physicians.

The significance of distance and orientation of restriction endonuclease recognition sites in viral DNA genomes

Studies on phage T3 and T7 have shown that these viruses avoid restriction not only by the phage-coded Ocr (and S-adenosylmethionine hydrolase) protein functions or by the complete loss of specific recognition sites for certain restriction endonucleases from their genomes, but also that there are two additional modes: resistance towards EcoP15 (which recognizes a non-symmetrical sequence) is achieved by an identical orientation of all the recognition sites in the virus genome (strand bias) and in the case of EcoRII by the extreme reduction in number and thereby greater distance between recognition sites in the genome. These observations led to the discovery that certain restriction endonucleases require the simultaneous cooperation with two DNA sites for their function, as well as to the ongoing elucidation of the molecular modes of action of these enzymes. Type II and type III enzymes display fundamentally different mechanisms of protein-DNA interaction. For EcoRII we favor a model of simultaneous binding of two DNA sites to a dimeric enzyme molecule (neighbouring sites of the same, looping, DNA molecule or sites located on different DNA molecules), while the action of EcoP15 seems to conform with a tracking-collision model of two enzyme molecules bound to inversely oriented recognition sites. In addition to podoviruses T3 and T7, strand bias of recognition sequences for different type III DNA modification-restriction enzymes is also observed in the inoviruses M13, IKE and PF3.

Type III restriction endonucleases translocate DNA in a reaction driven by recognition site-specific ATP hydrolysis

Type III restriction/modification systems recognize short non-palindromic sequences, only one strand of which can be methylated. Replication of type III-modified DNA produces completely unmethylated recognition sites which, according to classical mechanisms of restriction, should be signals for restriction. We have shown previously that suicidal restriction by the type III enzyme EcoP15I is prevented if all the unmodified sites are in the same orientation: restriction by EcoP15I requires a pair of unmethylated, inversely oriented recognition sites. We have now addressed the molecular mechanism of site orientation-specific DNA restriction. EcoP15I is demonstrated to possess an intrinsic ATPase activity, the potential driving force of DNA translocation. The ATPase activity is uniquely recognition site-specific, but EcoP15I-modified sites also support the reaction. EcoP15I DNA restriction patterns are shown to be predetermined by the enzyme-to-site ratio, in that site-saturating enzyme levels elicit cleavage exclusively between the closest pair of head-to-head oriented sites. DNA restriction is blocked by Lac repressor bound in the intervening sequence between the two EcoP15I sites. These results rule out DNA looping and strongly suggest that cleavage is triggered by the close proximity of two convergently tracking EcoP15I-DNA complexes.

Restriction endonucleases functionally interacting with two DNA sites

Simultaneous interaction with two recognition sites was found to be a precondition for DNA cleavage by certain type-II and type-III restriction endonucleases. Nevertheless, the molecular mechanisms of the protein-DNA interaction are different between members of both classes of enzymes.

Hyperexpressed EcoRII renatured from inclusion bodies and native enzyme both exhibit essential cooperativity with two DNA sites

EcoRII was the first restriction endonuclease (ENase) reported needing the cooperative interaction with at least two DNA sites for activity. We constructed an EcoRII-overproducing strain of Escherichia coli by placing the coding sequence under control of the T7 gene 10 regulatory elements. The yield of EcoRII expression could be increased to about 10% of total soluble cellular protein. Inclusion bodies are formed that mainly consist of insoluble EcoRII molecules. After solubilization by 6 M guanidine hydrochloride refolding of the enzyme was achieved by dilution into appropriate buffer. The endonuclease was purified to homogeneity from both the soluble protein fraction and the protein renatured from inclusion bodies. Their identity was proven by circular dichroism and analysis of enzyme activity with respect to the special substrate requirements of EcoRII. It is shown that EcoRII cleavage of oligodeoxyribonucleotide duplexes (oligo duplexes) with only one recognition site follows a sigmoidal concentration dependence, i.e., they cannot be cleaved below a distinct low DNA concentration where simultaneous interaction with two substrate molecules is no longer possible. We demonstrate that the restriction of oligo duplexes containing two recognition sites does not show this concentration dependence, confirming an intramolecular site cooperativity.

Barriers to forgoing nutrition and hydration in nursing homes

In the two decades since the Karen Quinlan case first brought the issues that now go under the heading of the "right to die" to the attention of the courts and the public, a well-accepted legal consensus has developed about the law governing the forgoing of life-sustaining medical treatment. Law and clinical medical practice do not always run in tandem, however, and what law prescribes does not always occur in practice. One aspect of the legal consensus-that artificial nutrition and hydration is a medical treatment and thus may be withheld or withdrawn according to the same procedures and standards as other life-sustaining medical treatments-is probably less well accepted than the remainder. For reasons that I will explain, this is understandable. But what is puzzling is that this element of the consensus seems to be even less well accepted in nursing homes than in acute-care hospitals.

The Consortium Ethics Program: an approach to establishing a permanent regional ethics network

This paper describes the first three-year experience of the Consortium Ethics Program (CEP-1) of the University of Pittsburgh Center for Medical Ethics, and also outlines plans for the second three-year phase (CEP-2) of this experiment in continuing ethics education. In existence since 1990, the CEP has the primary goal of creating a cost-effective, permanent ethics resource network, by utilizing the educational resources of a university bioethics center and the practical expertise of a regional hospital council. The CEP's conception and specific components stem from recognition of the need to make each hospital a major focus of educational efforts, and to provide academic support for the in-house activities of the representatives from each institution.

The legal consensus about foregoing life-sustaining treatment: its status and its prospects

The legal consensus that has evolved through adjudication and legislation since the Karen Quinlan case in 1976 is founded on the premise that there is a bright line between passive euthanasia and active euthanasia. Indeed, the term passive euthanasia is often eschewed in favor of less emotionally-laden terminology such as "forgoing life-sustaining treatment" or "terminating life support" so as to further sever any possible connection with active euthanasia. Legal approval has been bestowed upon passive euthanasia under certain circumstances while active euthanasia is routinely condemned. This consensus was put to a test in 1990 when the United States Supreme Court ruled on the Cruzan case. However, the Court's narrow decision did not upset the consensus, and in the most significant appellate decisions handed down by state courts since Cruzan, there has been a reaffirmation--and possibly even an extension--of the consensus. Two other threats to the legal consensus about forgoing life-sustaining treatment have begun to manifest themselves: the increasing pressure for mercy killing and "futility" cases. Both of these challenge the fundamental premises on which the consensus is grounded.

Type III restriction enzymes need two inversely oriented recognition sites for DNA cleavage

Type III restriction/modification enzyme recognize short, non-palindromic sequences that can be methylated on only one strand, with the paradoxical consequence that during replication of what is in effect hemimethylated DNA totally unmodified sites arise. Why the unmodified sites are not subject to suicidal restriction was not clear. Here we show that restriction requires two unmodified recognition sites that can be separated by different distances but which must be in inverse orientation. All of the unmodified sites in newly replicated DNA are of course in the same orientation, which explains why they are not restricted. This result may be of relevance to other manifestations of anisotropy in double-stranded DNA, such as genetic imprinting.

Activation of restriction endonuclease EcoRII does not depend on the cleavage of stimulator DNA

The restriction endonuclease EcoRII is unable to cleave DNA molecules when recognition sites are very far apart. The enzyme, however can be activated in the presence of DNA molecules with a high frequency of EcoRII sites or by oligonucleotides containing recognition sites: Addition of the activator molecules stimulates cleavage of the refractory substrate. We now show that endonucleolysis of the stimulator molecules is not a necessary prerequisite of enzyme activation. A total EcoRII digest of pBR322 DNA or oligonucleotide duplexes with simulated EcoRII ends (containing the 5' phosphate group), as well as oligonucleotide duplexes containing modified bases within the EcoRII site, making them resistant to cleavage, are all capable of enzyme activation. For activation EcoRII requires the interaction with at least two recognition sites. The two sites may be on the same DNA molecule, on different oligonucleotide duplexes, or on one DNA molecule and one oligonucleotide duplex. The efficiency of functional intramolecular cooperation decreases with increasing distance between the sites. Intermolecular site interaction is inversely related to the size of the stimulator oligonucleotide duplex. The data are in agreement with a model whereby EcoRII simultaneously interacts with two recognition sites in the active complex, but cleavage of the site serving as an allosteric activator is not necessary.

Legal myths about terminating life support

There are a number of myths about what the law permits concerning the termination of life support, some of which spring from a fundamental misconception of what law is. A serious misunderstanding of the law can lead to tragic results for physicians, health care institutions, patients, and families. These misunderstandings are (1) anything that is not specifically permitted by law is prohibited; (2) termination of life support is murder or suicide; (3) a patient must be terminally ill for life support to be stopped; (4) it is permissible to terminate extraordinary treatments, but not ordinary ones; (5) it is permissible to withhold treatment, but once started, it must be continued; (6) stopping tube feeding is legally different from stopping other treatments; (7) termination of life support requires going to court; and (8) living wills are not legal.

M.EcoP15 methylates the second adenine in its recognition sequence

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