VEGF-A related SNPs: a cardiovascular context

Cardiovascular diseases (CVDs) are the leading cause of death worldwide. Currently, cardiovascular disease risk algorithms play a role in primary prevention. However, this is complicated by a lack of powerfully predictive biomarkers that could be observed in individuals before the onset of overt symptoms. A key potential biomarker for heart disease is the vascular endothelial growth factor (VEGF-A), a molecule that plays a pivotal role in blood vessel formation. This molecule has a complex biological role in the cardiovascular system due to the processes it influences, and its production is impacted by various CVD risk factors. Research in different populations has shown single nucleotide polymorphisms (SNPs) may affect circulating VEGF-A plasma levels, with some variants associated with the development of CVDs, as well as CVD risk factors. This minireview aims to give an overview of the VEGF family, and of the SNPs reported to influence VEGF-A levels, cardiovascular disease, and other risk factors used in CVD risk assessments.

Multimodal cues improve prey localization under complex environmental conditions

Predators often eavesdrop on sexual displays of their prey. These displays can provide multimodal cues that aid predators, but the benefits in attending to them should depend on the environmental sensory conditions under which they forage. We assessed whether bats hunting for frogs use multimodal cues to locate their prey and whether their use varies with ambient conditions. We used a robotic set-up mimicking the sexual display of a male túngara frog (Physalaemus pustulosus) to test prey assessment by fringe-lipped bats (Trachops cirrhosus). These predatory bats primarily use sound of the frog's call to find their prey, but the bats also use echolocation cues returning from the frog's dynamically moving vocal sac. In the first experiment, we show that multimodal cues affect attack behaviour: bats made narrower flank attack angles on multimodal trials compared with unimodal trials during which they could only rely on the sound of the frog. In the second experiment, we explored the bat's use of prey cues in an acoustically more complex environment. Túngara frogs often form mixed-species choruses with other frogs, including the hourglass frog (Dendropsophus ebraccatus). Using a multi-speaker set-up, we tested bat approaches and attacks on the robofrog under three different levels of acoustic complexity: no calling D. ebraccatus males, two calling D. ebraccatus males and five D. ebraccatus males. We found that bats are more directional in their approach to the robofrog when more D. ebraccatus males were calling. Thus, bats seemed to benefit more from multimodal cues when confronted with increased levels of acoustic complexity in their foraging environments. Our data have important consequences for our understanding of the evolution of multimodal sexual displays as they reveal how environmental conditions can alter the natural selection pressures acting on them.

Goal setting for health behavior change: evidence from an obesity intervention for rural low-income women

INTRODUCTION

Rural, minority populations are disproportionately affected by overweight and obesity and may benefit from lifestyle modification programs that are tailored to meet their unique needs. Obesity interventions commonly use goal setting as a behavior change strategy; however, few have investigated the specific contribution of goal setting to behavior change and/or identified the mechanisms by which goal setting may have an impact on behavior change. Furthermore, studies have not examined goal setting processes among racial/ethnic minorities. Using data from an obesity intervention for predominately minority women in rural North Carolina, this study sought to examine whether intervention participation resulted in working on goals and using goal setting strategies which in turn affected health behavior outcomes. It also examined racial/ethnic group differences in working on goals and use of goal setting strategies.

METHODS

Data came from a community-based participatory research project to address obesity among low-income, predominately minority women in rural North Carolina. A quasi-experimental intervention design was used. Participants included 485 women aged 18 years and over. Intervention participants (n=208) received health information and goal setting support through group meetings and tailored newsletters. Comparison participants (n = 277) received newsletters on topics unrelated to obesity. Surveys assessed physical activity, fruit and vegetable intake, goal-related stage of change, and use of goal setting strategies. Chi squared statistics were used to assess intervention group differences in changes in goal-related stage of change and use of goal setting strategies as well as racial/ethnic group differences in stage of change and use of goal setting strategies at baseline. The causal steps approach of Baron and Kenny was used to assess mediation.

RESULTS

Intervention compared to comparison participants were more likely to move from contemplation to action/maintenance for the goals of improving diet (58% intervention, 44% comparison, p= 0.04) and physical activity (56% intervention, 31% comparison, p ≤ 0.0001). Intervention group differences were not found for moving from precontemplation to a higher category. At baseline, black compared to white participants were more likely to be working on the goals of getting a better education (p < 0.0001), owning a home (p < 0.01), starting a business (p < 0.0001), and improving job skills (p <0.05). For whites only, intervention participants were more likely than comparison participants to move from contemplation to action/maintenance for the goal of improving diet ( p< 0.05). For both blacks (p < 0.05) and whites (p < 0.0001), intervention participants were more likely than comparison participants to move from contemplation to action/maintenance for the goal of increasing physical activity. For all participants, progression in stages of change mediated the intervention effect on physical activity, but not fruit and vegetable intake. The intervention did not reveal an impact on use of goal setting strategies.

CONCLUSIONS

In this sample of low-income, rural women, the intervention's goal setting component influenced behavior change for participants who were contemplating lifestyle changes at baseline. Racial/ethnic group differences in goal setting indicate the need to gain greater understanding of individual, social, and environmental factors that may uniquely have an impact on goal setting, and the importance of tailoring obesity intervention strategies for optimal, sustainable behavior change.

Risky ripples allow bats and frogs to eavesdrop on a multisensory sexual display

Animal displays are often perceived by intended and unintended receivers in more than one sensory system. In addition, cues that are an incidental consequence of signal production can also be perceived by different receivers, even when the receivers use different sensory systems to perceive them. Here we show that the vocal responses of male túngara frogs (Physalaemus pustulosus) increase twofold when call-induced water ripples are added to the acoustic component of a rival's call. Hunting bats (Trachops cirrhosus) can echolocate this signal by-product and prefer to attack model frogs when ripples are added to the acoustic component of the call. This study illustrates how the perception of a signal by-product by intended and unintended receivers through different sensory systems generates both costs and benefits for the signaler.

Signal Perception in Frogs and Bats and the Evolution of Mating Signals

Psychophysics measures the relationship between a stimulus's physical magnitude and its perceived magnitude. Because decisions are based on perception of stimuli, this relationship is critical to understanding decision-making. We tested whether psychophysical laws explain how female túngara frogs (Physalaemus pustulosus) and frog-eating bats (Trachops cirrhosus) compare male frog calls, and how this imposes selection on call evolution. Although both frogs and bats prefer more elaborate calls, they are less selective as call elaboration increases, because preference is based on stimulus ratios. Thus, as call elaboration increases, both relative attractiveness and relative predation risk decrease because of how receivers perceive and compare stimuli. Our data show that female cognition can limit the evolution of sexual signal elaboration.

Clinical correlation of brain MRI and MRS abnormalities in patients with Wilson disease

BACKGROUND

The progression of Wilson disease (WD), a disorder of copper metabolism, can be arrested by chelation therapy. However, neurologic deficits may persist despite adequate treatment. MRI is used to assess patients with WD, but previous attempts to correlate clinical progression with the investigation findings have often been unsuccessful.

OBJECTIVE

To identify MR visible markers that could help stratify disease severity and to clarify the mechanism of persistent neurologic deficit after treatment.

METHODS

MRI and proton MR spectroscopy (1H-MRS) were performed in 17 patients with WD. MRI was assessed semiquantitatively and used to locate volumes of interest (voxels) in the striatum for 1H-MRS.

RESULTS

MRI showed abnormalities predominantly confined to those patients with neurologic features of WD. The 1H spectra demonstrated a reduction of N-acetylaspartate and N-acetylaspartylglutamate (2.05 mM; p < 0.01) in those patients with neurologic features but not in patients without clinical neurologic involvement (0.42 mM; p > 0.1) in comparison with age-matched normal control subjects. Choline was also reduced in both patient groups (0.08 mM; p < 0.01) compared with age-matched controls.

CONCLUSIONS

There may be a biochemical correlate of tissue-specific dysfunction in patients with Wilson disease who develop neurologic features. These changes appear to be present despite prior clinical improvement and may imply a need for additional treatment.

Hypnotic devices may be more than placebo

The study attempted to assess the effectiveness of two devices in facilitating the induction of hypnosis in subjects preselected as low in hypnotizability. Undergraduates were exposed to no treatment (control) or one of four combinations of devices during the induction phase of being administered the Stanford Hypnotic Susceptibility Scale, Form B of Weitzenhoffer and Hilgard (1959). Analyses revealed only one of the conditions resulted in a significant difference in subjects' realness ratings of hypnotic items and an increase in hypnotizability score. If the effect is more than a chance significance of placebo, the underlying mechanisms remain unknown.

Identifying hypnotic sequelae: the problem of attribution

A case of apparent hypnotic sequelae occurring in a non-clinical research context (involving a college student) is reported. Following his participation in a group session in which a standard hypnotic susceptibility scale was administered, 19 year-old Michael reported a number of reactions common to the hypnotic sequelae literature including dizziness, a mild headache, trembling, and slight nausea. An interview with Michael revealed several alternative sources of his reaction, highlighting the ever-present problem of attribution.

Molecular characterisation of the Xenopus laevis chaperonin gene Cctg

By library screening and PCR we have obtained cDNA clones which encode the gamma subunit of the CCT chaperonin complex from Xenopus laevis. The gene (XlCctg), which encodes the CCT gamma subunit contains an open reading frame which codes for 547 amino acid residues (60 kDa) and the predicted amino acid sequence shares a high degree of sequence identity with other CCT gamma homologues. The XlCctg mRNA measures 2.1 kb and is expressed ubiquitously in all of the X. laevis tissues examined. The mRNA levels of XlCctg are significantly higher in the ovary compared with other tissues.

In search of predictors of hypnotic sequelae

The present one-group correlational study was an attempt to examine questionnaire data that included medical and psychosocial histories and an inventory of fears, social problems, and previous stressful situations in an effort to determine if any predictors of negative sequelae to hypnosis would emerge. After completing questionnaires, undergraduates (n = 432) were administered a group hypnotic susceptibility scale, then were given sequelae questionnaires to complete within two hours, and another two days later. Significant correlations were obtained between occurrence of aftereffects and susceptibility score, number of somatic complaints, and number of previous stressful situations. Results are discussed in the context of the overall ability of these data to predict hypnotic sequelae.

Is differential item difficulty specific to hypnosis?

Previous hypnosis studies obtaining retrospective depth reports (e.g., Perry & Laurence, 1980) or retrospective realness reports (e.g., Page & Handley, 1992) have found a "parallel nonoverlapping" pattern between mean depth or realness and susceptibility scale items for high- through low-susceptible subjects. To determine if such a pattern, as well as differential item difficulty in general, is specific to hypnosis, 98 undergraduates were administered the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A) of Shor and Orne (1962) as a "test of visual and motor imagination," omitting the eye-closure induction (item #2). A pattern similar to other studies that employed hypnosis was produced. While supporting attribution theory (Bowers, 1973), results also indicate that differences in item difficulty are not specific to hypnosis, but instead are related more broadly to imagination.

Acetyl-CoA carboxylase exerts strong flux control over lipid synthesis in plants

The importance of acetyl-CoA carboxylase in regulation of lipid synthesis for barley and maize leaves has been quantitatively assessed using, as specific inhibitors, the herbicides fluazifop and sethoxydim. Apparent flux control coefficients of about 0.58 and 0.52 were determined for acetyl-CoA carboxylase in barley and maize leaves, respectively. These results show that acetyl-CoA carboxylase is the major flux controlling enzyme for light-stimulated lipid synthesis in these tissues.

Phase I trial of recombinant human granulocyte-macrophage colony-stimulating factor derived from yeast in patients with breast cancer receiving cyclophosphamide, doxorubicin, and fluorouracil

PURPOSE

To establish the optimum biologic dose and maximal-tolerated dose (MTD) of once-daily, subcutaneous recombinant human granulocyte-macrophage colony-stimulating factor derived from yeast (RhuGM-CSF) in patients with breast cancer.

PATIENTS AND METHODS

Seventeen patients with either newly diagnosed breast cancer with more than four involved axillary nodes (five patients) or metastatic breast cancer (12 patients) were treated with cyclophosphamide 1 g/m2, doxorubicin 50 mg/m2, and fluorouracil 500 mg/m2 (CAF) intravenously (IV) once every 3 weeks. RhuGM-CSF was administered subcutaneously once daily for 14 days after the second and third CAF cycles, at one of three dose levels.

RESULTS

The 125-micrograms/m2/d RhuGM-CSF dose level shortened the duration of neutropenia in only one of three patients. The 250-micrograms/m2/d level was effective in shortening the duration of the neutropenic nadir (< .5 x 10(9)/dL) by 2 or more days in five of six patients. The 500-micrograms/m2/d level caused severe toxicity (chest pain, two patients; deep vein thrombosis, one patient) in three of eight patients.

CONCLUSION

RhuGM-CSF administered once daily at the 250-micrograms/m2/d level is well tolerated and effective in shortening the duration of the neutrophil nadir by 2 or more days after CAF therapy.

The use of hypnosis in cocaine addiction

An unusual case is presented in which hypnosis was successfully used to overcome a $500 (five grams) per day cocaine addiction. The subject was a female in her twenties. Six months into her addiction, she acquired a commercial weight-control tape that she used successfully to stop smoking cigarettes (mentally substituting the word "smoking"), as well as to bring her down from her cocaine high and allow her to fall asleep. After approximately 8 months of addiction, she decided to use the tape in an attempt to overcome the addiction itself. Over the next 4 months, she listened to the tape three times a day, mentally substituting the word "coke." At the end of this period, her addiction was broken, and she has been drug free for the past 9 years. Her withdrawal and recovery were extraordinary because hypnosis was the only intervention, and no support network of any kind was available.

The effect of preventive measures in reducing aftereffects to hypnosis

In the present study we assessed the efficacy of several procedures in minimizing the occurrence of aftereffects of a hypnotic induction. We gave experimental subjects (n = 347) a brief lecture dispelling some myths about hypnosis, told them no psychological treatment would be undertaken, and then administered the Harvard Group Scale of Hypnotic Susceptibility, Form A (HGSHS:A) in which all references to aftereffects had been removed. We gave the standard version of the HGSHS:A to control subjects (n = 340). Although the treatment condition did not reduce the overall incidence of effects, long-term effects were significantly reduced. Medical and psychosocial histories were obtained from subjects prior to the induction, but they proved to be of limited value in predicting sequelae. Contrary to the results of Coe & Ryken (1979), hypnosis produced more frequent sequelae than a nonhypnotic classroom experience (watching a film followed by an introductory psychology lecture) for subjects in an ad hoc control group.

Cloning and sequencing of a full length cDNA encoding ovine lipoprotein lipase

A cDNA clone encoding lipoprotein lipase has been isolated from an ovine adipocyte library. Sequencing of this clone has revealed a single open reading frame encoding a 450 amino acid protein. Comparison with known LPL sequences from other species shows a high degree of conservation in the sequence of the protein and in the 5' untranslated region of the DNA sequence.

The effect of prior knowledge of hypnotic items on hypnotic performance and depth

First we exposed experimental subjects to either the hypnotic items they were about to experience or to those items embedded in a longer list of hypnotic items. We then asked them to give item-difficulty ratings prior to administration of a standard group susceptibility scale. Controls received no prior exposure to any hypnotic items. We obtained four dependent measures: hypnotic susceptibility score, an in-hypnosis depth report, Field (1965) Depth Inventory score, and retrospective depth reports. The three groups did not differ significantly on any of the dependent measures. Although this result differs from that of Shor, Pistole, Easton, and Kihlstrom (1984), who found that prior knowledge of items depressed susceptibility scores, this may be due to procedural differences between the two studies. Subjects' self-predictions of item difficulty were poor to modest, and accuracy of predictions was not related to any of the four dependent measures.

Effects of "deepening" techniques on hypnotic depth and responding

The present study attempted to assess the effectiveness of commonly used deepening techniques and of surreptitiously provided stimulation on hypnotizability scores, in-hypnosis depth reports, retrospective realness ratings, and the Field Inventory of Hypnotic Depth (Field, 1965). High, medium, and low hypnotizables were assigned in equal numbers to 1 of 3 groups, each containing 54 Ss. Controls were compared to Ss receiving 2 deepening techniques or 2 suggestions for positive and negative hallucinations that were surreptitiously enhanced. Of the 4 dependent measures employed, the only significant difference between groups related to a change in depth reports for the manipulation items themselves, leading to the conclusion that the effect of the techniques was at best minimal and transient. Some methodological and conceptual issues are also discussed.

Clark Hull and his role in the study of hypnosis

Clark L. Hull made many contributions to the field of hypnosis. The contributions discussed in this paper include his attempts to dispel misconceptions about hypnosis, comparisons of capacities in the hypnotic state with those in the awake state, a sampling of early findings that are still valid today, and examples of his contributions to methodology. Additionally, the roots of many modern-day models and concepts are to be found in his early works.

The assessment of viability in isolated rat hepatocytes

Isolated rat hepatocytes are used in many metabolic studies, but the viability of these cell preparations is often not adequately established. The present study shows that ATP content is a more reliable index of metabolic viability than trypan blue exclusion. At some of the low trypan blue exclusion levels quoted in the literature, a high percentage of cell preparations is likely to be nonviable by the criterion of ATP content. We suggest that ATP content measured on initial cell preparations and at the end of all incubation procedures is essential for establishing cell viability for metabolic studies on isolated hepatocytes.

The importance of alcohol dehydrogenase in regulation of ethanol metabolism in rat liver cells

We used titration with the inhibitors tetramethylene sulphoxide and isobutyramide to assess quantitatively the importance of alcohol dehydrogenase in regulation of ethanol oxidation in rat hepatocytes. In hepatocytes isolated from starved rats the apparent Flux Control Coefficient (calculated assuming a single-substrate irreversible reaction with non-competitive inhibition) of alcohol dehydrogenase is 0.3-0.5. Adjustment of this coefficient to allow for alcohol dehydrogenase being a two-substrate reversible enzyme increases the value by 1.3-1.4-fold. The final value of the Flux Control Coefficient of 0.5-0.7 indicates that alcohol dehydrogenase is a major rate-determining enzyme, but that other factors also have a regulatory role. In hepatocytes from fed rats the Flux Control Coefficient for alcohol dehydrogenase decreases with increasing acetaldehyde concentration. This suggests that, as acetaldehyde concentrations rise, control of the pathway shifts from alcohol dehydrogenase to other enzymes, particularly aldehyde dehydrogenase. There is not a single rate-determining step for the ethanol metabolism pathway and control is shared among several steps.

A comparison of the effects of standardized Chiasson and eye-closure inductions on susceptibility scores

Numerous induction techniques have been described in the literature, many of which are standardized, facilitating their use in research. Recent studies have compared inductions for their effects on susceptibility scores (e.g., Spanos, Lush, Smith, & de Groh, 1986; Woolson, 1986), finding little or no differences. In the present study we tested a Chiasson (1973) induction technique (recently standardized) for its relative efficacy at inducing hypnosis as measured by the Stanford Hypnotic Susceptibility Scale, Form A (SHSS:A) of Weitzenhoffer and Hilgard (1959). Subjects were 80 volunteer undergraduates at a midwestern university. We administered the SHSS:A using its standard eye-closure induction to half of the subjects; half were given the SHSS:A using the Chiasson induction. Following dehypnosis, all subjects gave a subjective rating of their depth. The results indicated that the two standard inductions have a comparable effectiveness as measured by susceptibility scores and subjective depth ratings.

Psychogenic and physiological sequelae to hypnosis: two case reports

Two cases of hypnotic sequelae occurring in a research context (with a non-clinical college population) are reported. Case 1 was a male who experienced retroactive amnesia following hypnosis: He was unable to recall familiar telephone numbers later that day. This was not a continuation of an earlier confusion or drowsiness (as is often found) since he indicated he was wide awake following hypnosis. Two parallels exist with previous reports: unpleasant childhood experiences with chemical anesthesia and a conflict involving a wish to experience hypnosis but a reluctance to relinquish control. Case 2 was a female who, while in hypnosis, experienced an apparent epileptic seizure that had characteristics of both petit mal and grand mal seizures. Although having a history of epilepsy, she had not had a seizure in 7 years. We suspect that the seizure was psychogenic and may have been triggered by wording used in the hypnotic scale or other similarities. Possible mechanisms are discussed and preventative recommendations are made.

An attempt to induce lower moral reasoning under hypnotic and task-motivated age regression

In this study, we attempted to partially replicate and extend the findings of the Page (1985) study of hypnotic age regression and moral reasoning. The Kohlberg (1976) Moral Judgment Interview (MJI) was used to assess the initial stage of moral reasoning in 32 adults who were preselected on the basis of their hypnotic susceptibility. Subjects were hypnotized and age regressed to two of four possible ages (16, 13, 10, and 7), or were given task-motivation instructions before being age regressed. All were then administered the MJI, which involves the resolution of certain dilemmas. Both groups were able to lower their moral reasoning scores when given age regression instructions, but no significant differences were found between groups. Thus the results of this study are inconsistent with those of Page (1985), but are consistent with those of O'Brien et al. (1977). Reasons for the failure to reaffirm the earlier results of Page (1985) are discussed.

Hypnotic age regression and moral reasoning

Moral reasoning was assessed with two dilemmas from the Kohlberg Moral Judgment Interview (1976) in 7 adults who were hypnotically age regressed to four ages: 15, 12, 9, and 6 years. Seven adults in a control group under task-motivation instructions were age regressed to the same ages and administered the dilemmas. Age-regressed moral maturity scores for both groups were compared to pretest scores, to data for actual 15-, 12-, 9-, and 6-year-olds from other studies, and to each other. Both groups were able to lower their moral reasoning scores when given age-regression instructions; however, hypnosis subjects not only scored lower than task-motivation subjects but also more closely resembled the levels of reasoning used by children at these ages. The results provide some support for a distinction between age regression through hypnosis and age regression through task-motivation instructions.

Earthquake Shaking and Damage to Buildings

Ground shaking close to the causative fault of an earthquake is more intense than it was previously believed to be. This raises the possibility that large numbers of buildings and other structures are not sufficiently resistant for the intense levels of shaking that can occur close to the fault. Many structures were built before earthquake codes were adopted; others were built according to codes formulated when less was known about the intensity of near-fault shaking. Although many building types are more resistant than conventional design analyses imply, the margin of safety is difficult to quantify. Many modern structures, such as freeways, have not been subjected to and tested by near-fault shaking in major earthquakes (magnitude 7 or greater). Damage patterns in recent moderate-sized earthquakes occurring in or adjacent to urbanized areas (17), however, indicate that many structures, including some modern ones designed to meet earthquake code requirements, cannot withstand the severe shaking that can occur close to a fault. It is necessary to review the ground motion assumed and the methods utilized in the design of important existing structures and, if necessary, to strengthen or modify the use of structures that are found to be weak. New structures situated close to active faults should be designed on the basis of ground motion estimates greater than those used in the past. The ultimate balance between risk of earthquake losses and cost for both remedial strengthening and improved earthquake-resistant construction must be decided by the public. Scientists and engineers must inform the public about earthquake shaking and its effect on structures. The exposure to damage from seismic shaking is steadily increasing because of continuing urbanization and the increasing complexity of lifeline systems, such as power, water, transportation, and communication systems. In the near future we should expect additional painful examples of the damage potential of moderate-sized earthquakes in urban areas. Over a longer time span, however, we can significantly reduce the risk to life and property from seismic shaking through better land utilization, improved building codes and construction practices, and at least the gradual replacement of poor buildings by more resistant buildings. Progress toward reducing risk from seismic shaking through better building design is slowed by deficiencies in our knowledge about the nature of damaging ground motion and the failure mechanisms in structures. For example, lacking observational data, seismologists must rely on simplified theoretical and numerical models of the earthquake process to estimate near-fault ground motion, especially for earthquakes as large as magnitude 7 and 8. Because such models have not been adequately tested against data, their reliability is unknown. Engineers lack detailed information about failure processes in structures during an earthquake. Although many structures have been instrumented to measure their response to an earthquake, few records have been obtained from buildings that actually sustained significant structural damage and few structures are properly instrumented to measure all the modes of deformation that are likely to contribute to failure. Moreover, the fact that many structures have withstood ground motion more intense than that assumed in their design indicates that conventional methods of design do not take into account important contributions to earthquake resistance by nonstructural elements and by the ability of structural elements to deform inelastically without necessarily causing failure of the structure. It is fortunate when such reserve resistance exists, but better understanding of the sources of reserve strength is needed to determine how large a margin of safety they confer and how they might be affected by changes in construction practices and materials with time. In the next few years we look forward to significant advances in knowledge and to more effective application of what is already known, largely because of substantial funding of research related to seismic engineering by the National Science Foundation (18). The increasing number of strong-motion seismographs operating in seismically active regions (19) will likely provide for the first time a number of records of damaging levels of ground motion. Significant effort is being directed toward obtaining near-fault records, although many probable sites of future large earthquakes remain inadequately instrumented, especially outside the conterminous United States. New and more complete information on building response and damage mechanisms will be obtained by improved instrumentation of structures and through laboratory investigations of failure in structures and structural elements. Further developments in computer technology and in computer modeling techniques will permit more realistic simulations of the seismic response of soils and structures that take into account their inelastic behavior and their strain-dependent properties. Earthquake design codes will continually be revised to better utilize existing knowledge concerning the nature of strong ground motion and the dynamic behavior of buildings during earthquakes and to incorporate new knowledge and also experiences gained from future earthquakes. We believe that application of new knowledge, improvements in earthquake-resistant design and construction, and remedial strengthening or replacement of weak existing structures can significantly reduce our current level of exposure to earthquake hazards.

Point Mugu, California, Earthquake of 21 February 1973 and Its Aftershocks

Seismological investigations show that the Point Mugu earthquake involved north-south crustal shortening deep within the complex fault zone that marks the southern front of the Transverse Ranges province. This earthquake sequence results from the same stress system responsible for the deformation in this province in the Pliocene through Holocene and draws attention to the significant earthquake hazard that the southern frontal fault system poses to the Los Angeles metropolitan area.