Regulatable gene expression systems for gene therapy applications: progress and future challenges

Gene therapy aims to revert diseased phenotypes by the use of both viral and nonviral gene delivery systems. Substantial progress has been made in making gene transfer vehicles more efficient, less toxic, and nonimmunogenic and in allowing long-term transgene expression. One of the key issues in successfully implementing gene therapies in the clinical setting is to be able to regulate gene expression very tightly and consistently as and when it is needed. The regulation ought to be achievable using a compound that should be nontoxic, be able to penetrate into the desired target tissue or organ, and have a half-life of a few hours (as opposed to minutes or days) so that when withdrawn or added (depending on the regulatable system used) gene expression can be turned "on" or "off" quickly and effectively. Also, the genetic switches employed should ideally be nonimmunogenic in the host. The ability to switch transgenes on and off would be of paramount importance not only when the therapy is no longer needed, but also in the case of the development of adverse side effects to the therapy. Many regulatable systems are currently under development and some, i.e., the tetracycline-dependent transcriptional switch, have been used successfully for in vivo preclinical applications. Despite this, there are no examples of switches that have been employed in a human clinical trial. In this review, we aim to highlight the main regulatable systems currently under development, the gene transfer systems employed for their expression, and also the preclinical models in which they have been used successfully. We also discuss the substantial challenges that still remain before these regulatable switches can be employed in the clinical setting.

X11alpha modulates secretory and endocytic trafficking and metabolism of amyloid precursor protein: mutational analysis of the YENPTY sequence

The neuronal adaptor X11alpha interacts with the conserved -GYENPTY- sequence in the C-terminus of amyloid precursor protein (APP) or its Swedish mutation (APPswe) to inhibit Abeta40 and Abeta42 secretion. We hypothesized that the -YENP- motif essential for APP endocytosis is also essential for X11alpha-mediated effects on APP trafficking and metabolism, and that X11alpha modulates APP metabolism in both secretory and endocytic pathways. X11alpha failed to interact with the endocytic-defective APPswe mutants Y738A, N740A, or P741A, and thus did not modulate their trafficking or metabolism. However, endocytic-competent APPswe Y743A had unique trafficking and metabolism including a prolonged half-life and increased secretion of catabolites compared with APPswe. In contrast to endocytic-defective mutants, X11alpha interacted with APPswe Y743A as well as with APPswe. Thus, similar to APPswe, coexpression of X11alpha with APPswe Y743A retarded its maturation, prolonged its half-life, and inhibited APPs, Abeta40, and Abeta42 secretion. Collectively, these data suggest that by direct interaction with the APPswe -YENP- motif in the cytoplasmic tail, X11alpha modulated its trafficking and processing in both secretory and endocytic compartments, and may reduce secretion of Abeta generated in either pathway.

Minnesota Multiphasic Personality Inventory as a predictor of operative results in thoracic outlet syndrome

Twenty-one women and four men who had been operated upon for thoracic outlet syndrome were evaluated for symptom relief, and the results were blindly correlated with their scores on a Minnesota Multiphasic Personality Inventory (MMPI). Of the 14 patients who had abnormal results on the MMPI, five rated themselves improved, seven unchanged, and two worse as a result of surgery. Of the 11 patients who had a normal MMPI, ten rated themselves improved and one unchanged (P less than .05). Patients were then divided into two groups--those who were improved and those who were not improved by surgery--and mean MMPI scale scores were obtained for each group. There were significant differences for MMPI scales 1 and 3 (P less than .05).

Normative data on the Missouri Children's Picture Series and the Missouri Children's Behavior Checklist with Southern black children

Normative data are presented for Southern black children on two objective personality inventories for children: the Missouri Children's Picture Series (MCPS), a child picture-sorting task, and the Missouri Children's Behavior Checklist (MBCL), a parent rating scale. The MCPS was administered to 615 black children attending public schools in a low socioeconomic area of the southeast United States. Parents returned the MBCL on 437 of the children. Means and standard deviations on eight MCPS personality scales and six MCBL behavior rating scales are presented for black males and females at ages 5 through 16, and effects of age, sex, and various scale intercorrelations are discussed. Results suggest systematic age and sex differences on the various scales for black children that are quite atypical when compared with the MCPS in other samples. Various empirical questions regarding the validity of these instruments when used with Southern black children are raised.

The selection of paraprofessional telephone counselors using the California Psychological Inventory

Comparing groups of 36 veteran telephone counselors with 36 matched age and sex control subjects on the CPI revealed substantial differences on a number of scales. Subsequent development of weighted formulae via regression analysis led to very accurate predictions as to which individuals were telephone counselors or controls. Various cutoff scores and their uses are discussed.

Expectations about effectiveness of telephone crisis intervention

50 male and 50 female college students who had heard of but never actually used a crisis center were asked about their expectations for the quality of help received and its impact on their lives. Expectations were generally very positive and were compared to experiences of actual callers to a crisis center.

Two- and three-point classification of MMPI profiles in which scales 2, 7, and 8 are the highest elevations

Two-point and three-point methods of classifying MMPI profiles were compared using 174 students who sought psychological treatment at a college student mental health clinic and who generated MMPI profiles with scales 2, 7, and 8 as their highest evaluations, (or obtained two of those three scales as their two highest elevations). Behavioral correlates were determined by comparing each profile type to the remainder of the population by means of the chi2 statistic for males and females. Each two-point code type was compared to the comparable subgroup of its parent three-point code type. Important differences in interpretation were present between two- and three-point classification methods, particularly when sex of subject was considered, suggesting that method of classification and sex of subject are important variables in the accurate interpretation of college student MMPI profiles.

Behavioral correlates of infrequent two-point MMPI code types at a university mental health center

Presented interpretive correlates for 95 college students who were seeking mental health services and who generated the following infrequently occurring MMPI code types: Spike 2, 2-0/0-2, 2-4/4-2, 2-6/6-2, 3-4/4-3, 3-9/9-3, 4-7/7-4, 6-7/7-6, 7-9/9-7, and Spike O. Descriptors were derived from intake interview and mental status information collected without knowledge of the MMPI profile. Those items that discriminated between each profile type and the remainder of the student mental health population (Chi Square, alpha = .05, .01) are presented as tentative interpretive descriptors that may be helpful in generating hypotheses for use with college student psychiatric outpatients.

Cross validation of the 2-8/8-2 MMPI code type for young adult psychiatric outpatients

Young adults attending a college student mental health center and obtaining 2 and 8 as their highest scale elevations (and not scale 7 as the third elevation) on the MMPI were compared to other patients at the center on 175 descriptors obtained from intake interviews. Those items which discriminated (chi2, p less than .05) 2-8/8-2 patients from others in the sample are presented in relationship to the descriptors obtained for this code type by other investigators. The statements generated by the Marks and Seeman interpretive system for adults were then reanalyzed by the Chi Square method to demonstrate the differential effect of statistical method upon code type interpretation. Although previously established correlates of 2-8/8-2 profiles were partially validated, a number of different descriptors emerge for males and females in this population. Questions are raised and discussed concerning methodologies for generating interpretive statements for various clinical populations.

Variables affecting subjects' ethical ratings of proposed experiments

The present study examined students' ratings of ethics in psychological research. Four levels of research presentation were employed: traditional deception, sensitization, consumer-review, and informed consent. The results reaffirmed findings that students responded with significantly less concern about traditional deception in experimentation than did psychologists. Some differences were noted as a function of how the research was presented; sensitized students and consumer-review students responded in a somewhat more ethically stringent manner than did students in the other groups.

Behavioral correlates for within-normal-limit MMPI profiles with and without elevated K in students at a university mental health center

Young adults who were attending a college student mental health center and who obtained MMPI profiles with clinical scales within normal limits with and without elevated K were compared to all other patients at the center on 175 descriptors obtained from intake interviews. Those items that discriminated (x2, p less than .05) students who obtained these profile types from others are reported as tentative MMPI interpretive correlates for patients in similar settings. Correlates ranged from those indicative of situational difficulties to serious psychopathology, and clear sex differences were present. It is concluded that within-normal-limit profiles do not indicate psychological normality when they occur in such a setting and that useful interpretive information can be identified for these, as well as clinically elevated profile types.

An empirical investigation of the modeling of depression

To investigate the effects of viewing various films on affect, 200 volunteer subjects were assigned to 10 groups following a modified Solomon four-group design. Five groups received pretesting and five groups received no pretesting before being exposed to one of five treatments and follow-up testing 2 or 3 wk. later with the State Form of the Multiple Affect Adjective Check List and the Depression Check List. The treatments required viewing films of an actor who conveyed depression, positive affect, and neutral affect, and a no-film control. Subjects viewing a film were administered 13 semantic differential adjective pairs to obtain the observers' perception of the character in the film and the California Psychological Inventory. Depression increased following the depressed and neutral film conditions, and decreased from posttest to follow-up test, while the positive and no-film control conditions produced no change from pretest to posttest levels of depression. Similar results were found for the measure of anxiety but not for hostility. Subjects tended to be affected in the same way by the treatments regardless of their pretreatment levels of depression, anxiety, or hostility. Relationships between the changes in depression from pre-to posttest and personality variables were not confirmed.

Behavioral correlates for spike-4, spike-9, and 4-9/9-4 MMPI profiles in students at a university mental health center

Numerous investigators have noted that spike-4, spike-9, and 4-9/9-4 profiles occur with an unusually high frequency in college students. Five hundred and fifty files of college students who requested outpatient psychiatric services were reviewed, and the data from 47 files were extracted in which the student patient had a clinically elevated spike-4, spike-9, or 4-9/9-4 profile. Numerous significant psychopathological behavioral correlates were found for each profile type, which supports the contention that these profile types are reflective of significant psychopathology and are not examples of benign deviations of a particular sample from the original normative group.

Intellectual and personality changes associated with carotid endarterectomy

Eleven patients with at least 40-50% carotid artery stenosis were given intelligence and personality tests just prior to and 6 weeks after carotid endarterectomy, a surgical procedure designed to remove arteriosclerotic blockage. When compared with 8 control patients, endarterectomy patients showed increases in Perceptual-Organization IQ, decreases in time to complete a perceptual motor task, and significant reductions in suspicion, confusion, disorientation, and other personality symptoms generally associated with senility.

MMPI behavioral correlates of spike-5 and two-point code types with scale 5 as one elevation

Data from 550 student outpatient psychiatric files were extracted and summarized on record sheets. Base rates for the entire population were determined. MMPI profiles were grouped according to their highest two-point elevations or by single elevation when only one scale was elevated above T-score 70. All profiles with only a scale-5 elevation or for which scale 5 was one of the two highest clinical elevations were removed from the profile population, and the corresponding correlates for these groups of profiles were compared to those for the remainder of the population. Spike-5 profiles indicate basically normal adjustment, while 2-5/5-2, 4-5/5-4, 7-5/5-7, and 8-5/5-8 profiles all indicate varying degrees of psychopathology.

The improvement of cognition and personality after carotid endarterectomy

Seventeen patients with at least 50% carotid artery stenosis were given intelligence and personality tests just prior to and 6 weeks after carotid endarterectomy. When compared with nine control patients, the endarterectomy patients showed increases in verbal-comprehension I.Q., perceptual-organization I.Q., decreases in time to complete perceptual motor tasks, decrease in asphasic signs, and significant reductions in anxiety, suspicion, confusion, disorientation, and other personality symptoms generally associated with senility. Statistical evaluation showed these results to be valid.

MMPI profile predictors for successful and expired open heart surgery patients

A total of 31 patients (17 females, 14 males) who were scheduled for open heart surgery were administered an MMPI within 1 week prior to surgery. Of the 31 patients, 20 (13 females, 7 males) survived and 11 (4 females and 7 males) did not survive the operation. MMPI scale T-score comparisons were made within sex between survivors and nonsurvivors. Surviving and expired males did not differ on any MMPI scales, while expired females had much higher average scale 1 and 3 elevations than did their surviving counterparts (p less than .05). Subsequent comparisons of expired and surviving female patients with 1-3 profiles revealed that females with 1-3 profiles who expired had a higher average L scale T-score and a lower average scale 6 T-score (p less than .05). Cutting scores established to divide 1-3 female profiles into success and expired groups yielded two results: (1) an L scale T-score of 50 or above identified 100% of the expired females while it generated 40% false positives and no false negatives; and (2) a scale 6 T-score of 57 and below identified 100% of the expired females while it generated no false negatives and no false positives. These results are consistent with previous research and may be used to predict mortality for prospective female open heart surgery patients with implications for psychotherapeutic assistance prior to surgery to increase prospects for success.

Developmental analysis of schedule-induced polydipsia

In a developmental analysis of schedule-induced polydipsia (SIP), 8 female, albino rats were exposed to either a FI-60-sec. or a VI-60-sec. reinforcement schedule with 4 Ss in each group. Results indicated that the adventitious reinforcement explanation for SIP is not tenable, since licks did not occur with equal probability in all periods of the interpellet interval during SIP development; lick bursts coming in contact with pellet deliveries were a result rather than a cause of SIP; and SIP developed more slowly on the VI than on the FI schedule.

Schedule-induced alcohol and water intakes in rats on a FFI-60-sec. schedule

4 food-deprived, female albino rats were exposed to baseline and free-reinforcement schedule conditions in which either water or alcohol solution were concurrently available or the alcohol solution was available alone. The results replicate previous findings but are not explicable by current motivational or reinforcement theoretical notions. Practical and theoretical considerations with regard to these data are discussed.