Spring and latch dynamics can act as control pathways in ultrafast systems.

Ultrafast movements propelled by springs and released by latches are thought limited to energetic adjustments prior to movement, and seemingly cannot adjust once movement begins. Even so, across the tree of life, ultrafast organisms navigate dynamic environments and generate a range of movements, suggesting unrecognized capabilities for control. We develop a framework of control pathways leveraging the non-linear dynamics of spring-propelled, latch-released systems. We analytically model spring dynamics and develop reduced-parameter models of latch dynamics to quantify how they can be tuned internally or through changing external environments. Using Lagrangian mechanics, we test feedforward and feedback control implementation via spring and latch dynamics. We establish through empirically-informed modeling that ultrafast movement can be controllably varied during latch release and spring propulsion. A deeper understanding of the interconnection between multiple control pathways, and the tunability of each control pathway, in ultrafast biomechanical systems presented here has the potential to expand the capabilities of synthetic ultra-fast systems and provides a new framework to understand the behaviors of fast organisms subject to perturbations and environmental non-idealities.

Beyond power amplification: latch-mediated spring actuation is an emerging framework for the study of diverse elastic systems.

Rapid biological movements, such as the extraordinary strikes of mantis shrimp and accelerations of jumping insects, have captivated generations of scientists and engineers. These organisms store energy in elastic structures (e.g. springs) and then rapidly release it using latches, such that movement is driven by the rapid conversion of stored elastic to kinetic energy using springs, with the dynamics of this conversion mediated by latches. Initially drawn to these systems by an interest in the muscle power limits of small jumping insects, biologists established the idea of power amplification, which refers both to a measurement technique and to a conceptual framework defined by the mechanical power output of a system exceeding muscle limits. However, the field of fast elastically driven movements has expanded to encompass diverse biological and synthetic systems that do not have muscles - such as the surface tension catapults of fungal spores and launches of plant seeds. Furthermore, while latches have been recognized as an essential part of many elastic systems, their role in mediating the storage and release of elastic energy from the spring is only now being elucidated. Here, we critically examine the metrics and concepts of power amplification and encourage a framework centered on latch-mediated spring actuation (LaMSA). We emphasize approaches and metrics of LaMSA systems that will forge a pathway toward a principled, interdisciplinary field.

Osteoporosis: implications for risk reduction in the college setting.

Osteoporosis is often considered a chronic disease of older adulthood. As with many chronic diseases, lifestyle behaviors adopted during young adulthood are important risk factors for future development of osteoporosis. The college student population represents the age group in which optimal bone development is likely to occur and certain lifestyle behaviors are reinforced. Therefore, risk factors for osteoporosis, including nutritional insufficiency of calcium and vitamin D, smoking, alcohol abuse, excessive exercise, use of steroids, and high-protein diets, have special relevance for this target population. The authors examine risk factors for osteoporosis that are especially relevant to the college health setting and offer intervention strategies for college health professionals.

Using home visits for multiple purposes: the Comprehensive Child Development Program.

The Comprehensive Child Development Program (CCDP) was a two-generation program that employed case management and home visiting to assure low-income children and their parents of a range of educational, health, and social services. Designed to meet the complex needs of disadvantaged families, CCDP was predicted by its planners to generate positive short- and long-term effects across a variety of child and parent well-being indicators. This article describes the CCDP program and reviews the results of the program evaluation. The evaluation of 21 project sites and 4,410 families followed for five years found no statistically significant impact of CCDP on program families when they were compared with control families in any of the assessed domains: early childhood education, child and family health, parenting education, family economic self-sufficiency, or maternal life course. The authors conclude that the results of this evaluation do not support home visiting as an effective means of social service delivery and parenting education for low-income families.

Inducible expression of protein kinase CK2 in mammalian cells. Evidence for functional specialization of CK2 isoforms.

Protein kinase CK2 (formerly casein kinase II) exhibits elevated expression in a variety of cancers, induces lymphocyte transformation in transgenic mice, and collaborates with Ha-Ras in fibroblast transformation. To systematically examine the cellular functions of CK2, human osteosarcoma U2-OS cells constitutively expressing a tetracycline-regulated transactivator were stably transfected with a bidirectional plasmid encoding either catalytic isoform of CK2 (i.e. CK2alpha or CK2alpha') together with the regulatory CK2beta subunit in order to increase the cellular levels of either CK2 isoform. To interfere with either CK2 isoform, cells were also transfected with kinase-inactive CK2alpha or CK2alpha' (i. e. GK2alpha (K68M) or CK2alpha'(K69M)) together with CK2beta. In these cells, removal of tetracycline from the growth medium stimulated coordinate expression of catalytic and regulatory CK2 subunits. Increased expression of active forms of CK2alpha or CK2alpha' resulted in modest decreases in cell proliferation, suggesting that optimal levels of CK2 are required for optimal proliferation. By comparison, the effects of induced expression of kinase-inactive CK2alpha differed significantly from the effects of induced expression of kinase-inactive CK2alpha'. Of particular interest is the dramatic attenuation of proliferation that is observed following induction of CK2alpha'(K69M), but not following induction of CK2alpha(K68M). These results provide evidence for functional specialization of CK2 isoforms in mammalian cells. Moreover, cell lines exhibiting regulatable expression of CK2 will facilitate efforts to systematically elucidate its cellular functions.

An efficient protocol for linker scanning mutagenesis: analysis of the translational regulation of an Escherichia coli RNA polymerase subunit gene.

A protocol has been developed that is capable of saturating regions hundreds of basepairs in length with linker scanning mutations. The efficacy of this method stems from the design of the linker scanning mutagenesis (LSM) cassette which is composed of a selectable marker flanked by two oligonucleotides, each of which contains a recognition site for a different restriction endonuclease. The cleavage site for one endonuclease is within its recognition site, while the second endonuclease cleaves in the target DNA beyond the end of the cassette. Digestion with these endonucleases and subsequent ligation results in the replacement of 12 bp of the original target sequence with 12 bp of the linker scanning oligonucleotide. We have used this protocol to mutagenize a span of approximately 400 bp surrounding the start site of the gene for the beta subunit (rpoB) of Escherichia coli RNA polymerase. The translation of the beta mRNA has been shown previously to be regulated by the intracellular concentration of either beta or beta'. Analysis of the linker scanning mutations indicates that sequences extending a considerable distance both upstream and downstream of the start site are required for normal translation. Also a site that appears to be involved in translational repression by excess beta' has been identified.

A set of compatible tac promoter expression vectors.

A series of expression vectors have been developed which all contain an identical expression cassette comprised of the lacIq gene, the tac promoter, a multiple cloning site (MCS) and a downstream transcriptional terminator. This cassette has been inserted into four distinct plasmid backbones, each of which is from a separate incompatibility group and carries a different drug resistance gene. Therefore, different combinations of these expression plasmids can be stably maintained together.

Synthesis of the beta and beta' subunits of Escherichia coli RNA polymerase is autogenously regulated in vivo by both transcriptional and translational mechanisms.

Numerous experiments have indicated that the synthesis of RNA polymerase (beta beta' alpha 2 sigma 70) in Escherichia coli is autogenously regulated. In the present study, we have examined expression of the rpoB and rpoC genes which encode the beta and beta' subunits of RNA polymerase. These genes are the distal cistrons of the rplKAJLrpoBC ribosomal protein-RNA polymerase transcription unit. Both transcriptional (operon) and translational (gene) fusions of either rpoB or rpoC to the lacZ reporter were used to monitor their in vivo expression by inserting single copies of these fusions into the bacterial chromosome on integration-proficient lambda vectors. In order to examine the expression of the rpoBC genes in response to varied intracellular concentrations of the RNA polymerase subunits, a series of expression plasmids carrying the rpoB, rpoC, rpoA (alpha) and rpoD (sigma 70) genes in different combinations were then introduced into these cells. Elevated concentrations of either beta or beta' were found to repress the expression of both rpoB and rpoC at the translational level. However, the simultaneous increase in the concentration of all the subunits that comprise holoenzyme repressed the transcription of rpoBC. To determine the site of this repression, additional operon fusions were utilized which placed lacZ downstream of each of the transcriptional regulatory sites of this gene cluster, including two promoters, rplKp and rplJp, and a transcriptional attenuator in the rplL-rpoB intercistronic region. Expression from these fusions showed that transcriptional repression is achieved primarily by reducing initiation at both upstream promoters, coupled with a small increase in termination at the attenuator.

A refined vector system for the in vitro construction of single-copy transcriptional or translational fusions to lacZ.

New single-copy vectors based on lambda phage have been developed for creating either transcriptional (operon) or translational (gene) fusions to the lacZ gene. The improvements of these vectors over the previous lambda TL61 vector include: (i) incorporation of a tetracycline-resistance-encoding gene (TcR) to permit direct selection of lysogens, (ii) low-background beta-galactosidase activity, (iii) the ability to accept DNA inserts up to 8 kb in size, and (iv) an expanded multiple cloning site (MCS). The new transcriptional fusion vector retains the RNase III processing site downstream from the MCS which ensures independent translation of lacZ. The set of three translational fusion vectors allow for convenient subcloning in any of the three translational reading frames.

The effect of a single affective HIV/AIDS educational program on college students' knowledge and attitudes.

The number of AIDS cases, since its identification by the Centers for Disease Control (CDC) in 1981, has continued to escalate at a very alarming rate. A population at increased risk of acquiring AIDS is college students, because of their behavior, especially personal and sexual exploration (D'Augelli & Kennedy, 1989; American College Health Association, 1988; Hirschorn, 1987).

Two-generation programs: design, cost, and short-term effectiveness.

Two-generation programs are relatively new attempts to deal with the nation's social ills. In two-generation programs, services such as early childhood educational programs are offered to children to help them get the best possible start in life, while, at the same time, parents are offered training to help enhance their parenting skills, and education, literacy, or job training to help them become economically self-sufficient. These multistrategy programs are relatively new additions to the broad array of programs designed to serve children and families, but many have already been the subjects of fairly sophisticated evaluations. This article describes two-generation programs and how they differ from earlier single-focus approaches to serve children and families. In-depth descriptions of six premier two-generation programs are used to illustrate the variability in content and costs of these programs. The short-term results of these six programs are reviewed and indicate mixed and modest results in promoting the development of children and improving the parenting skills and economic self-sufficiency of parents. The results suggest several lessons, and the article concludes with recommendations for program improvement and future research.

Does occupational stereotyping still exist?

We surveyed 113 college students regarding their views of certain occupational stereotypes. Our results indicated that in this population gender was related to the subjects' views of occupations as either male, female, or neutral, and that the father's primary occupation significantly affected the subjects' views of only one occupation--clinical sociologist. The mother's occupational seemed to have no effect.

The Ohio AIDS Prevention Survey: a study of psychometric properties.

The reliability of a measuring instrument is a major criterion for assessing its quality and adequacy. This article describes reliability pilot testing done with the Ohio AIDS Prevention Survey (Fellner & Thomas, 1989-90) in a sample of sexually active women of childbearing age. Previous alpha reliabilities of the knowledge scale of the survey have ranged from .71-.81, while the reliabilities of the attitudes and beliefs scale have ranged from .33-.45. In this sample, reliability measures for the knowledge and attitudes and beliefs scales were .65 and .45, respectively. The results of this study indicate that the Ohio AIDS Prevention Survey is clearly in its developmental stages and that further development of the survey is necessary prior to continued use in public health settings.

Improved vector system for constructing transcriptional fusions that ensures independent translation of lacZ.

An improved vector system has been developed for the in vitro construction of transcriptional fusions to lacZ. The principal feature is an RNaseIII cleavage site inserted between the polylinker cloning site and the promoterless lacZ gene. When these vectors are used to construct transcriptional fusions, the subsequent cleavage of the hybrid mRNA at the RNaseIII site generates an unchanging 5' end for the lacZ mRNA. In contrast to earlier vectors, this feature helps to ensure independent translation of the lacZ mRNA and, thus, the level of beta-galactosidase produced should accurately reflect the frequency of transcription of the upstream DNA sequences. Additional modifications of the vectors include removal of a weak transcriptional terminator between the cloning site and lacZ, insertion of a terminator downstream of lac, and alteration of restriction endonuclease cleavage sites to facilitate the in vitro construction of fusions. Both multicopy plasmid (pTL61T) and single-copy lambda (lambda TL61) vectors have been assembled. These vectors should be generally useful in scanning for transcriptional regulatory signals.

Biomechanical foot orthotics: a retrospective study.

Foot orthotics are becoming recognized as an important consideration in the correction of lower extremity alignment and mechanical dysfunctions. There are many different foot orthotics on the market today claiming to relieve pain and enhance foot function. Unfortunately, minimal research has been conducted investigating the effectiveness of foot orthotics in adult patient populations. The purpose of this study was to determine the degree of pain relief experienced by patients, the ability of patients to return to their previous levels of activity associated with the duration of use of the orthotics, and patient compliance. This study also discusses the specific deformity for which the orthotic was prescribed and the degree of posting necessary to compensate for the deformity. Fifty-three subjects, 20 males and 33 females, responded to a questionnaire survey. The type of foot deformity and the orthotic prescription are also presented for each subject. The responses to the questions were correlated with an individual patient chart review. In addition, chi-square analysis was used to determine the level of significance between the specific deformity and the age and weight of the patients. The level of significance was determined between the patient's ability to adjust to the orthotics and their continued use of the orthotics. Finally, the significance of the orthotic treatment was compared to four other treatment interventions. Ninety-six percent of the patients reported relief from pain with the use of the prescribed foot orthotic. Ninety-four percent of the patients were still wearing the orthotic, and 52% reported that they would not leave home without them in their shoes at the time the survey was conducted. Seventy percent of the patients reported that they were able to return to their previous level of activity with the use of the foot orthotics.J Orthop Sports Phys Ther 1988;10(6):205-212.

Arthroscopy of the elbow.

For arthroscopy of the elbow to be safe and effective, the arthroscopist must develop a systematic and reproducible arthroscopic examination technique. We believe that the technique and the identification of anatomic structures described in this article provide a safe and reliable means of performing this procedure. Attention to detail, especially when establishing the portals, is essential in performing a safe examination and in avoiding damage to the neurovascular structures. We prefer the 4-mm, 30-degree-angled arthroscope. It provides the wide field of view necessary for both diagnostic and operative elbow arthroscopy. The large percentage of excellent and good results in patients who have had correction of mechanical disorders of the elbow has been encouraging. Removal of loose bodies and resection of impinging olecranon osteophytes produced the best functional results. Chondroplasties of the radial head and capitellum produced less satisfactory results than did the correction of mechanical disorders. In conclusion, arthroscopy of the elbow is an effective diagnostic procedure and is effective in treating certain intraarticular problems with minimal morbidity and rapid return to function. However, attention to detail is essential to prevent compromise of the surrounding neurovascular structures or damage to the delicate articular cartilage.

Close relationship of the major excreted protein of transformed murine fibroblasts to thiol-dependent cathepsins.

Complementary DNA clones corresponding to 638 nucleotides of the messenger RNA encoding the major portion of murine major excreted protein have been isolated and sequenced. The amino acid sequence of a part of the murine major excreted protein deduced from the DNA sequence reveals substantial and significant homology with the cysteine proteases actinidin, rat cathepsin H, and papain. Since the amount of murine major excreted protein secreted by cultured cells is often enhanced by transformation, it is implicated in oncogenic phenomena and may play a role in the metastatic process by virtue of its proteolytic activity.

Report of the 1984 ASHA membership survey.

The results of the most recent American School Health Association (ASHA) membership survey, conducted by ASHA to retain its continuing education units provider status granted in 1981 by the American Nurses' Association are reported. Results of the 1984 survey are compared to two previous surveys, conducted in 1980 and 1982. Topics examined include membership demographics, attendance at national meetings, continuing education needs and preferences, maintaining professional competence, professional issues of importance to readers, and options for improving the usefulness of the Journal of School Health. Several membership trends are discussed and implications for future planning are noted.