The care of adolescents by obstetrician-gynecologists: a first look.

STUDY OBJECTIVE: To determine whether obstetrician-gynecologists who typically care for adolescent patients, what this care entails, and the adequacy of training opportunities in adolescent health care. DESIGN: A questionnaire designed to elicit information regarding practice patterns of obstetrician-gynecologists mailed to the American College of Obstetricians and Gynecologists Collaborative Ambulatory Practice Network. PARTICIPANTS: Obstetrician-gynecologists whose patient populations included girls under the age of 18. MAIN OUTCOME MEASURES: Items in the questionnaire were generated to determine what care obstetrician-gynecologists are providing to adolescents, whether this care meets practice guidelines of major medical organizations, and whether obstetrician-gynecologists are receiving adequate training to provide this care. RESULTS: Obstetrician-gynecologists frequently care for adolescent patients, with 72.6% seeing adolescents either monthly or weekly. The most frequently cited service needs pertained to reproductive health. Obstetrician-gynecologists also provide primary care, with 55.2% currently providing immunizations to adolescent patients. Nearly all (96.5%) plan to provide HPV immunizations. Most (80% or more) considered their residency training in obstetrics-gynecology on reproductive health to be adequate, but many reported inadequate or no training on primary care. CONCLUSIONS: Obstetrician-gynecologists are an important part of the health care team caring for female adolescent patients. There is a lack of training during residency in obstetrics-gynecology in adolescent primary care issues. Increased training of obstetrician-gynecologists in all aspects of adolescent health care may increase the pool of health care providers who care for adolescents adequately. Collaborative efforts among all adolescent health care providers can improve access to quality health care for adolescents and the health of this population.

Wild-type nonneuronal cells extend survival of SOD1 mutant motor neurons in ALS mice.

The most common inherited [correct] form of amyotrophic lateral sclerosis (ALS), a neurodegenerative disease affecting adult motor neurons, is caused by dominant mutations in the ubiquitously expressed Cu-Zn superoxide dismutase (SOD1). In chimeric mice that are mixtures of normal and SOD1 mutant-expressing cells, toxicity to motor neurons is shown to require damage from mutant SOD1 acting within nonneuronal cells. Normal motor neurons in SOD1 mutant chimeras develop aspects of ALS pathology. Most important, nonneuronal cells that do not express mutant SOD1 delay degeneration and significantly extend survival of mutant-expressing motor neurons.

Summary, conclusions and recommendations: adverse temperature levels in the human body.

In the spring of 2002, The World Health Organization workshop 'Adverse Temperature Levels in the Human Body' brought together scientists with expertise in biological effects of hyperthermia to review the data and determine the evidence that could be used to evaluate potential adverse effects from human exposures to radiofrequency (RF) electromagnetic radiation in the range of 10-300 GHz. Standards for RF exposure in this frequency range are based currently on thermal effects. Information was reviewed on the ability of hyperthermia, either to the whole body or to part of the body to affect physiology, particularly the heart and circulatory system, to induce other thermoregulatory responses such as sweating, to affect the performance of simple and complex mental tasks, to induce various heat-related disorders such as heat stroke and to damage body tissue. Risks to a variety of organs were considered. In addition, thresholds for effects on developing embryos and foetuses and possible carcinogenic effects were also examined. These findings were discussed in the context of known cellular and biochemical responses of cells and tissues to hyperthermia. The experts judged the relevance of each study for informing decision-makers on the scientific basis for establishing safe exposure levels. The consensus was that standards should consider both temperature and time of exposure, whenever possible.

Kinesin-mediated axonal transport of a membrane compartment containing beta-secretase and presenilin-1 requires APP.

Proteolytic processing of amyloid precursor protein (APP) generates amyloid-beta peptide and has been implicated in the pathogenesis of Alzheimer's disease. However, the normal function of APP, whether this function is related to the proteolytic processing of APP, and where this processing takes place in neurons in vivo remain unknown. We have previously shown that the axonal transport of APP in neurons is mediated by the direct binding of APP to the kinesin light chain subunit of kinesin-I, a microtubule motor protein. Here we identify an axonal membrane compartment that contains APP, beta-secretase and presenilin-1. The fast anterograde axonal transport of this compartment is mediated by APP and kinesin-I. Proteolytic processing of APP can occur in the compartment in vitro and in vivo in axons. This proteolysis generates amyloid-beta and a carboxy-terminal fragment of APP, and liberates kinesin-I from the membrane. These results suggest that APP functions as a kinesin-I membrane receptor, mediating the axonal transport of beta-secretase and presenilin-1, and that processing of APP to amyloid-beta by secretases can occur in an axonal membrane compartment transported by kinesin-I.

Disruption of axonal transport and neuronal viability by amyloid precursor protein mutations in Drosophila.

We tested the hypothesis that amyloid precursor protein (APP) and its relatives function as vesicular receptor proteins for kinesin-I. Deletion of the Drosophila APP-like gene (Appl) or overexpression of human APP695 or APPL constructs caused axonal transport phenotypes similar to kinesin and dynein mutants. Genetic reduction of kinesin-I expression enhanced while genetic reduction of dynein expression suppressed these phenotypes. Deletion of the C terminus of APP695 or APPL, including the kinesin binding region, disrupted axonal transport of APP695 and APPL and abolished the organelle accumulation phenotype. Neuronal apoptosis was induced only by overexpression of constructs containing both the C-terminal and Abeta regions of APP695. We discuss the possibility that axonal transport disruption may play a role in the neurodegenerative pathology of Alzheimer's disease.

Molecular motors: from one motor many tails to one motor many tales.

Kinesin and dynein molecular motor proteins generate the movement of a wide variety of materials in cells. Such movements are crucial for many different cellular and developmental functions, including organelle movement, localization of developmental determinants, mitosis, meiosis and possibly long-range signaling in neurons. Kinesins that control the dynamics of microtubules have also been discovered. Recent work has begun to identify processes in which defective molecular motor function can cause human disease.

Linkers, packages and pathways: new concepts in axonal transport.

The molecular mechanisms that generate efficient and directed transport of proteins and organelles in axons remain poorly understood. In the past year, many studies have identified specific transmembrane or scaffold proteins that might link motor proteins to their cargoes. These studies have also identified previously unsuspected pathways and raised the intriguing possibility that pre-packaged groups of functionally related proteins are transported together in the axon. Evidence suggests that fast molecular motor proteins have a role in slow axonal transport, and the axonal transport machinery has been implicated in the genesis of neurodegenerative diseases.

Polarized fluorescence microscopy of individual and many kinesin motors bound to axonemal microtubules.

Kinesin is a molecular motor that interacts with microtubules and uses the energy of ATP hydrolysis to produce force and movement in cells. To investigate the conformational changes associated with this mechanochemical energy conversion, we developed a fluorescence polarization microscope that allows us to obtain information on the orientation of single as well as many fluorophores. We attached either monofunctional or bifunctional fluorescent probes to the kinesin motor domain. Both types of labeled kinesins show anisotropic fluorescence signals when bound to axonemal microtubules, but the bifunctional probe is less mobile resulting in higher anisotropy. From the polarization experiments with the bifunctional probe, we determined the orientation of kinesin bound to microtubules in the presence of AMP-PNP and found close agreement with previous models derived from cryo-electron microscopy. We also compared the polarization anisotropy of monomeric and dimeric kinesin constructs bound to microtubules in the presence of AMP-PNP. Our results support models of mechanochemistry that require a state in which both motor domains of a kinesin dimer bind simultaneously with similar orientation with respect to the microtubule.

Functional analysis of mouse kinesin motor Kif3C.

Members of the kinesin II family are thought to play essential roles in many types of intracellular transport. One distinguishing feature of kinesin II is that it generally contains two different motor subunits from the Kif3 family. Three Kif3 family members (Kif3A, Kif3B, and Kif3C) have been identified and characterized in mice. Intracellular localization and biochemical studies previously suggested that Kif3C is an anterograde motor involved in anterograde axonal transport. To understand the in vivo function of the Kif3C gene, we used homologous recombination in embryonic stem cells to construct two different knockout mouse strains for the Kif3C gene. Both homozygous Kif3C mutants are viable, reproduce normally, and apparently develop normally. These results suggest that Kif3C is dispensable for normal neural development and behavior in the mouse.

Kinesin molecular motors: transport pathways, receptors, and human disease.

Kinesin molecular motor proteins are responsible for many of the major microtubule-dependent transport pathways in neuronal and non-neuronal cells. Elucidating the transport pathways mediated by kinesins, the identity of the cargoes moved, and the nature of the proteins that link kinesin motors to cargoes are areas of intense investigation. Kinesin-II recently was found to be required for transport in motile and nonmotile cilia and flagella where it is essential for proper left-right determination in mammalian development, sensory function in ciliated neurons, and opsin transport and viability in photoreceptors. Thus, these pathways and proteins may be prominent contributors to several human diseases including ciliary dyskinesias, situs inversus, and retinitis pigmentosa. Kinesin-I is needed to move many different types of cargoes in neuronal axons. Two candidates for receptor proteins that attach kinesin-I to vesicular cargoes were recently found. One candidate, sunday driver, is proposed to both link kinesin-I to an unknown vesicular cargo and to bind and organize the mitogen-activated protein kinase components of a c-Jun N-terminal kinase signaling module. A second candidate, amyloid precursor protein, is proposed to link kinesin-I to a different, also unknown, class of axonal vesicles. The finding of a possible functional interaction between kinesin-I and amyloid precursor protein may implicate kinesin-I based transport in the development of Alzheimer's disease.

ADP-induced rocking of the kinesin motor domain revealed by single-molecule fluorescence polarization microscopy.

Kinesin is an ATP-driven molecular motor protein that moves processively along microtubules. Despite considerable research, the detailed mechanism of kinesin motion remains elusive. We applied an enhanced suite of single- and multiple-molecule fluorescence polarization microscopy assays to report the orientation and mobility of kinesin molecules bound to microtubules as a function of nucleotide state. In the presence of analogs of ATP, ADP-Pi or in the absence of nucleotide, the kinesin head maintains a rigid orientation. In the presence of ADP, the motor domain of kinesin, still bound to the microtubule, adopts a previously undescribed, highly mobile state. This state may be general to the chemomechanical cycle of motor proteins; in the case of kinesin, the transition from a highly mobile to a rigid state after ADP release may contribute to the generation of the 8 nm step.

Functional analysis of mouse C-terminal kinesin motor KifC2.

Proteins of the kinesin superfamily define a class of microtubule-dependent motors that play crucial roles in cell division and intracellular transport. In the mouse, several kinesin motors have been characterized and are suggested to play roles in axonal and/or dendritic transport. One such kinesin is KifC2. Sequence and secondary structure analysis revealed that KifC2 is a member of the C-terminal motor family. Northern and Western blot analyses indicated that KifC2 is specifically expressed in both the central and peripheral nervous systems. The cellular locations of the KifC2 proteins were found to be mainly in neural cell bodies and dendrites but also in axons. To understand the in vivo function of the KifC2 gene, we used homologous recombination in embryonic stem cells to construct knockout mouse strains for the KifC2 gene. Homozygous KifC2 mutants were viable and reproduced normally, and their development was apparently normal. These results suggest that KifC2 is dispensable for normal neural development and behavior in the mouse.

Molecular cloning and functional analysis of mouse C-terminal kinesin motor KifC3.

Proteins of the kinesin superfamily define a class of microtubule-dependent motors that play crucial roles in cell division and intracellular transport. To study the molecular mechanism of intracellular transport involving microtubule-dependent motors, a cDNA encoding a new kinesin-like protein called KifC3 was cloned from a mouse brain cDNA library. Sequence and secondary structure analysis revealed that KifC3 is a member of the C-terminal motor family. In contrast to other mouse C-terminal motors, KifC3 is apparently ubiquitous and may have a general role in intracellular transport. To understand the in vivo function of the KifC3 gene, we used homologous recombination in embryonic stem cells to construct knockout mouse strains for the KifC3 gene. Homozygous mutants of the KifC3 gene are viable, reproduce normally, and apparently develop normally. These results suggest that KifC3 is dispensable for normal development and reproduction in the mouse.

Kinesin-dependent axonal transport is mediated by the sunday driver (SYD) protein.

A broadly conserved membrane-associated protein required for the functional interaction of kinesin-I with axonal cargo was identified. Mutations in sunday driver (syd) and the axonal transport motor kinesin-I cause similar phenotypes in Drosophila, including aberrant accumulations of axonal cargoes. GFP-tagged mammalian SYD localizes to tubulovesicular structures that costain for kinesin-I and a marker of the secretory pathway. Coimmunoprecipitation analysis indicates that mouse SYD forms a complex with kinesin-I in vivo. Yeast two-hybrid analysis and in vitro interaction studies reveal that SYD directly binds kinesin-I via the tetratricopeptide repeat (TPR) domain of kinesin light chain (KLC) with K(d) congruent with 200 nM. We propose that SYD mediates the axonal transport of at least one class of vesicles by interacting directly with KLC.

Cystic fibrosis patients with and without central nervous system complications following lung transplantation.

Central nervous system (CNS) complications occur more frequently in cystic fibrosis (CF) patients than other lung transplant recipients. The purpose of this study was to compare CF patients with and without CNS complications following lung transplantation, to identify risk factors for CNS events. Records of 21 patients with CF who underwent lung transplant between 1991-1996 were reviewed. Data were collected on multiple variables, including: age at transplant; gender; cytomegalovirus (CMV) status; cholesterol and triglyceride levels; sinusitis; percent ideal body weight (IBW); body mass index (BMI); augmented immunosuppression, acute lung rejection episodes (ALR); cyclosporine doses; electrolytes; magnesium, blood urea nitrogen (BUN), and creatinine levels; and 6-month survival. CNS complications identified were seizures, severe headaches (HA), strokes, or confusional episodes. Eleven of 21 patients (52%) with CF had CNS events: eight had seizures, five HA, three strokes, and one confusional episode. There was no difference in age at transplant, pretransplant percent IBW or BMI, cholesterol and triglyceride levels, or number of ALR. CMV mismatch and clinical sinusitis had no effect. Cyclosporine doses did not differ between groups at 30 days, or 3 or 6 months posttransplant. Both BUN and creatinine concentrations showed a rise over time that did not differ between groups. Potassium levels were within normal limits for both groups. While sodium levels did not differ between groups pretransplant, or at 30 days or 6 months posttransplant, a decrease in sodium values was seen at the time of CNS events. There was no difference in 6-month survival. We could not identify any pre- or posttransplant risk factors that predicted CNS events. It is likely that cyclosporine toxicity is the major cause of CNS complications. Despite the high rate of CNS events, the overall prognosis was good, and 6-month survival was not affected.

Genetic evidence for selective transport of opsin and arrestin by kinesin-II in mammalian photoreceptors.

To test whether kinesin-II is important for transport in the mammalian photoreceptor cilium, and to identify its potential cargoes, we used Cre-loxP mutagenesis to remove the kinesin-II subunit, KIF3A, specifically from photoreceptors. Complete loss of KIF3A caused large accumulations of opsin, arrestin, and membranes within the photoreceptor inner segment, while the localization of alpha-transducin was unaffected. Other membrane, organelle, and transport markers, as well as opsin processing appeared normal. Loss of KIF3A ultimately caused apoptotic photoreceptor cell death similar to a known opsin transport mutant. The data suggest that kinesin-II is required to transport opsin and arrestin from the inner to the outer segment and that blocks in this transport pathway lead to photoreceptor cell death as found in retinitis pigmentosa.