Inhibition of zona pellucida gene expression by antisense oligonucleotides injected into mouse oocytes

During murine oogenesis, the zona pellucida proteins (ZP1, ZP2, and ZP3) are synthesized and secreted to form an extracellular matrix that surrounds the oocyte and mediates specific biological functions essential to mammalian fertilization and early development. To investigate the relationship among the zona proteins during zona matrix assembly, we have undertaken to inhibit de novo biosynthesis of specific zona proteins with antisense oligonucleotides complementary to the 5'-ends of ZP2 (nucleotide position 19-42) and ZP3 (nucleotide 21-44) mRNAs. When injected into the cytoplasm of growing mouse oocytes, the antisense oligonucleotides targeted specific zona mRNAs for degradation, as confirmed by a RNase protection assay. Individual zona pellucida protein synthesis was followed by immunoprecipitation with ZP2- and ZP3-specific monoclonal antibodies. New zona protein synthesis from the targeted mRNA was abolished, but nontargeted zona protein continued to be synthesized. Interestingly, abolishment of either ZP2 or ZP3 protein synthesis prevented the incorporation of the other protein into the extracellular zona matrix. These results suggest that ZP2 and ZP3 proteins are independent of each other in their biosynthesis but are dependent upon each other for their incorporation into the zona pellucida matrix. This study provides an experimental system in which destruction of a targeted mRNA generates a transient loss-of-expression phenotype during mouse oocyte growth.

A modular artificial neural net for controlling a six-legged walking system

A system that controls the leg movement of an animal or a robot walking over irregular ground has to ensure stable support for the body and at the same time propel it forward. To do so, it has to react adaptively to unpredictable features of the environment. As part of our study of the underlying mechanisms, we present here a model for the control of the leg movement of a 6-legged walking system. The model is based on biological data obtained from the stick insect. It represents a combined treatment of realistic kinematics and biologically motivated, adaptive gait generation. The model extends a previous algorithmic model by substituting simple networks of artificial neurons for the algorithms previously used to control leg state and interleg coordination. Each system controlling an individual leg consists of three subnets. A hierarchically superior net contains two sensory and two 'premotor' units; it rhythmically suppresses the output of one or the other of the two subordinate nets. These are continuously active. They might be called the 'swing module' and the 'stance module' because they are responsible for controlling the swing (return stroke) and the stance (power stroke) movements, respectively. The swing module consists of three motor units and seven sensory units. It can produce appropriate return stroke movements for a broad range of initial and final positions, can cope with mechanical disturbances of the leg movement, and is able to react to an obstacle which hinders the normal performance of the swing movement. The complete model is able to walk at different speeds over irregular surfaces. The control system rapidly reestablishes a stable gait when the movement of the legs is disturbed.

General practitioners' tacit and stated policies in the prescription of lipid lowering agents

BACKGROUND

Research into general practitioners' prescribing behaviour with regard to lipid lowering agents has relied on survey methods which presume that doctors have insight into their prescribing behaviour and can describe it accurately.

AIM

This study set out to measure the tacit policies used by general practitioners in prescribing lipid lowering agents and to compare these with their stated policies.

METHOD

Effects of 13 separate cues on decisions to prescribe were examined. The cues included cholesterol levels and a number of associated risk factors for coronary heart disease. Doctors rated 130 imaginary cases presented by a computer. Thirty five general practitioners in the Plymouth area participated in the study. Their ages ranged from 31 to 55 years and all but four were men. The raw data in each case was a rating of the likelihood that the doctor would prescribe for the patient described. These were converted into statistical weightings by use of multiple linear regression. The pattern of (standardized) weights constituted the tacit policy for each doctor. Stated policies were measured in a subsequent interview by asking doctors to rate the influence of each cue.

RESULTS

Both tacit and stated policies diverged widely between different doctors. Most doctors overestimated the number of cues that had actually influenced their decisions, and many believed that they had taken into account associated factors for coronary heart disease when they had not. On lifestyle related risks doctors were generally less likely to treat overweight people and most stated this as their policy. Most were also less likely to treat smokers but some had the opposite policy. Those less likely to treat smokers were also less likely to treat obese patients. There was also considerable variation in the extent to which the doctors took account of the attitude of the patient to receiving treatment.

CONCLUSION

Doctors' policies are highly variable and particularly inconsistent in the treatment of smokers. Relevant risk factors may be ignored--even though they are understood--because the risk assessment involved is too psychologically complex a task to be performed intuitively. Decision aids and clear protocols are needed in this area.

Effects of electrical stimulation on lymphatic flow and limb volume in the rat

BACKGROUND AND PURPOSE

The mechanism by which electrical stimulation affects edema has not been elucidated. The purpose of this study was to determine whether subcontraction high-voltage stimulation (SC-HVS) (ie, electrical stimulation that did not elicit a visible contraction) applied to the right hind limbs of rats would (1) alter the rate of lymphatic uptake of injected albumin labeled with Evans blue dye (AL-EBD) and (2) affect experimentally induced edema.

SUBJECTS AND METHODS

The paws of 28 anesthetized Sprague-Dawley rats (mean weight = 263 g, SD = 48 g) were injected with AL-EBD. The experimental group (n = 13) received 1 hour of SC-HVS, and the control group (n = 15) received sham treatment consisting of the same treatment administered to the experimental group but without the SC-HVS. Blood samples and volume measurements were obtained at intervals over a 7-hour period.

RESULTS

Analysis of variance and post hoc testing indicated that higher amounts of AL-EBD were taken up by the lymph of the experimental group animals as compared with the control group animals at each time period following the treatment. The experimental group's AL-EBD reached significance immediately after treatment, whereas the control group required an additional 4 hours. There was no significant reduction in limb volume in either group.

CONCLUSION AND DISCUSSION

The SC-HVS significantly increased the uptake of AL-EBD by lymphatic vessels, but it did not cause a significant decrease in the induced edema. The results of this study indicate that SC-HVS has the potential to reduce edema by increasing lymphatic uptake of proteins.

Intersegmental and local interneurons in the metathorax of the stick insect Carausius morosus that monitor middle leg position

1. In the stick insect, proprioceptive information from the middle leg is used to define the target for the swing movement of the adjacent rear leg ("targeting behavior"). To investigate the underlying neural circuits, intracellular recordings were made in the ganglion controlling the rear leg, the metathoracic ganglion, while systematically moving the tarsus of the middle leg. 2. Several intersegmental interneurons and one local interneuron were identified as possible contributors to the targeting behavior. The intersegmental interneurons code the position of the middle leg tarsus in a highly simplified manner: test movements of the middle leg in the dorsal, lateral, and caudal directions from the standard starting position at right angles to the thorax elicit phasic-tonic responses in three different intersegmental neurons. The response in each interneuron actually reflects the movement and position at only one joint of the middle leg: for the neurons responding primarily to movement in the caudal, dorsal, and lateral test directions, the adequate stimulus is movement at the subcoxal joint, the coxa-trochanter joint, and the femur-tibia joint, respectively. 3. The metathoracic local interneuron integrates information from ipsilateral middle and rear legs in such a way as to provide an approximate measure of the distance between the two tarsi in the longitudinal direction. It is depolarized in a phasic-tonic manner both by caudal movements of the ipsilateral middle leg and by rostral movements of the ipsilateral rear leg. The adequate stimulus in each case is the change in the angle at the subcoxal joint of the leg moved. Depolarization of this neuron activates retractor motoneurons, which is consistent with a role in terminating the swing movement. 4. Altogether the results indicate first, that the targeting behavior could be controlled by very few intersegmental channels and, second, that the nervous system encodes the position of the middle leg tarsus in terms of joint angles rather than in abstract, body-centered coordinates.

Obstetrical and gynecological complications in fragile X carriers: a multicenter study

We have conducted a multicenter obstetrical and gynecological survey of women in fragile X families. Included in the study were 131 gene carriers (39 with a full mutation and 92 with a premutation) and 109 noncarriers. Analysis indicated that higher numbers of fragile X gene carriers reported having irregular menses and other gynecological complications. As a group they also experienced cessation of menses prior to age 40 years at a significantly higher rate. The data appear to indicate that the FMR1 gene may play a role in the development and proliferation of oogonia.

Ascertainment and severity of Marfan syndrome in a Scottish population

This study in north east Scotland has shown that Marfan syndrome has a minimal birth incidence of 1:9802 live births, a minimal prevalence of 1:14217, and that 8/30 (26.7%) of cases in our series are new mutations. The calculated mutation rate is 15 +/- 6.7 x 10(-6) and there is evidence of reduced reproductive fitness.

Biology and structure of the zona pellucida: a target for immunocontraception

Although reversible interference of sperm-egg interactions with pharmacological agents has not yet been achieved, animal models have provided increasing evidence that immunological reagents directed against mammalian gametes can effectively inhibit fertilization. One potential target of immunocontraception is the zona pellucida, an extracellular matrix that surrounds the growing oocyte and ovulated egg. Recent advances in our knowledge of the biosynthesis and molecular biology of the zona pellucida have provided much information useful in the rational design of immunocontraceptive vaccines. There remain, however, major obstacles to using immunological reagents to prevent fertilization, including potential toxic side effects, the lack of adequate delivery systems and the possibility of incomplete reversibility. This review summarizes current understanding of the production of the zona pellucida during folliculogenesis, the structure of the conserved proteins and genes in the zona pellucida, and the progress made in the development of immunocontraceptive strategies that focus on this oocyte-specific structure.

Control of human arm movements in two dimensions: paths and joint control in avoiding simple linear obstacles

In order to examine path planning and the control of redundant degrees of freedom in the human arm, the movements of the shoulder, elbow and wrist were recorded as subjects moved a pointer to a target and avoided a simple obstacle. With respect to joint control, the results show that the extra degree of freedom provided by the wrist is incorporated into target movements in a systematic manner for both large and small obstacles; it is not used only when there is no geometrical alternative. For the wrist, two strategies are apparent, depending upon the length of the obstacle. Wrist extension predominates for shorter obstacles, while flexion or extension and flexion predominate for longer obstacles. These wrist movements shorten the effective length of the distal segments (lower arm plus hand and pointer) and thus reduce the excursion required at the proximal joints. In part, they correspond to assuming the most comfortable arm configuration at each point in the new path necessitated by the obstacle and can be described by static cost functions. However, wrist extension is also used to move the hand and pointer away from the obstacle as shoulder and elbow movements carry the wrist itself towards the obstacle. Wrist flexion is also used to move the pointer tip rapidly past the obstacle. These components, which cannot be explained by static cost functions alone, confirm for the human arm the hypothesized use of redundant degrees of freedom in obstacle avoidance. With respect to path planning, the results show that the minimum distance between pointer and obstacle remains fairly constant over a large range of obstacle lengths; this relative invariance is interpreted to support the hypothesis that workspace coordinates are important for movement planning. However, minimum distance and several other path parameters do depend significantly on the orientation and location of the movement in the workspace. This inhomogeneity implies that movement planning does not occur exclusively in workspace coordinates; it suggests an influence of joint space criteria. In frontal movements, for example, the systematic decline in the minimum distance with increasing obstacle length is interpreted as a compromise reducing the amount of extra joint movement and the discomfort of arm configurations.

Preimplantation diagnosis or chorionic villus biopsy? Women's attitudes and preferences

The objective of this work was to assess women's attitudes and preferences to two methods of prenatal diagnosis for genetic disease: embryo and chorionic villus biopsy (CVS). The design involved a structured postal questionnaire sent to women in the Grampian region with different reproductive experiences. The population sample included 46 women who had had genetic counselling because of a family history of a single gene disorder, 18 women who had had CVS for a single gene disorder, 158 women who had had CVS for other reasons, 200 women who had recently delivered a normal baby and 50 women who had experience of in-vitro fertilization (IVF). The main outcome measures were attitudes to family limitation, prenatal diagnosis, termination for fetal abnormality, embryo biopsy and CVS. Of the women surveyed, 38% preferred embryo diagnosis, whereas 42% favoured CVS and termination. Women with previous experience of CVS preferred this option whereas those with experience of IVF as infertility treatment were more likely to favour embryo diagnosis, as were women who had had genetic counselling for a single gene disorder. It was concluded that a substantial number of women find embryo diagnosis more acceptable than CVS when the pregnancy is at high risk. This is especially true amongst those with experience of IVF or who are at risk themselves. A demand for embryo diagnosis has been demonstrated.

Antenatal cystic fibrosis carrier screening--whether, when and how?

Population screening for carriers of cystic fibrosis (CF) is now possible. Such screening may have both advantages and disadvantages and hence must be evaluated before it becomes routine practice. As the potential benefits of screening are wide and the drawbacks may include psychological effects, a combination of approaches is needed to assess screening thoroughly instead of only counting numbers of terminations or carrier tests. We describe the issues concerned and our methodology for a rigorous evaluation of population antenatal carrier screening for cystic fibrosis.

Reduction of animal use with improved procedure for acute tolerance assessment

A retrospective evaluation of previously conducted acute tolerance tests in rats and mice, following oral and intravenous routes of administration, and a review of the literature indicated that a minimum of three animals per group was adequate to characterize acute tolerance. Limited exploratory testing, using six compounds for which classical LD50 tests had been performed previously, indicated that fewer numbers of rats gave comparable results. A method is proposed by which the acute tolerance of a compound may be adequately characterized in both sexes using approximately 30 animals instead of the 70 to 100 used in the classical LD50 test. The objective of the testing procedure is identification of the maximum nonlethal dose or the minimum lethal dose, rather than determination of the LD50.

Control of Three- and Four-Joint Arm Movement: Strategies for a Manipulator With Redundant Degrees of Freedom

Control of arm movements when the number of joints exceeds the degrees of freedom necessary for the task requires a strategy for selecting specific arm configurations out of an infinite number of possibilities. This report reviews strategies used by human subjects to control the shoulder, elbow, and wrist (three degrees of freedom) while moving a pointer to positions in a horizontal plane (two degrees of freedom). Analysis of final arm configurations assumed when the pointer was at the target showed the following: (a) Final arm configurations were virtually independent of the configuration at the start of the pointing movement, (b) subjects avoided configurations subjectively felt to be uncomfortable (e.g., those with extreme flexion or extension of the wrist), and (c) the results could be simulated by assigning hypothetical cost functions to each joint and selecting the arm configuration that minimized the sum of the costs. The fitted cost functions qualitatively agreed with psychophysically determined comfort; they appeared to depend on joint angle and on muscular effort. Simple neural networks can learn implicit representations of these cost functions and use them to specify final arm configurations. The minimum cost principle can be extended to movements that use the fingers as a fourth movable segment. For this condition, however, experiments showed that final configurations of the arm depended upon initial configurations. Analysis of movement trajectories for arms with three degrees of freedom led to a control model in which the minimum cost principle is augmented by a mechanism that distributes required joint movements economically among the three joints and a mechanism that implements a degree of mass-spring control.

Affect and age: cross-sectional comparisons of Structure and prevalence

The self-reports of 207 young-adult (ages 18-30), 231 middle-aged (ages 31-59), and 828 older-adult (age 60 and over) Ss were used to study the structure of affect. Affects were represented by terms included in various circumplex arrays of emotions as presented by previous investigators. A set of 46 affects was subjected to exploratory analysis, and a final set of 38 affects was subjected to confirmatory factor analysis. The goodness of fit of each group's factor loadings to the hypothesized factors of positive affect, depression, anxiety-guilt, contentment, hostility, and shyness was not up to the desired .90 level, and some significant differences in factor structure were observed for each age-group comparison. There were few age differences in levels of positive affect. Depression was most frequent among younger Ss and least frequent among older Ss. Younger Ss were most often anxious and shy. Older Ss were most often content and least often hostile.

ZAP-1 DNA binding activity is first detected at the onset of zona pellucida gene expression in embryonic mouse oocytes

ZAP-1 (zona pellucida gene activating protein-1) is a putative transcription factor controlling the oocyte-specific expression of mouse and human zona pellucida genes. The DNA binding activity of ZAP-1 first appears in oocytes from 19-day-old mouse embryos and reaches a maximum level at 10 days after birth. This developmental profile closely parallels that of mouse zona pellucida gene transcription, which is detected in oocytes at 19 days of fetal life using a sensitive RT-PCR method and is maximal in 10-day-old animals. DNA binding activity similar to that of ZAP-1 is present in ovarian extracts from rat, human, and opossum, suggesting that the ZAP-1 protein may be conserved among mammals.

Rigid fixation of mandibular condyle fractures

This article reviews the anatomy and surgical approaches for treating fractures of the mandibular condyle with plate and screw fixation. Advantages and disadvantages of the preauricular, submandibular, intraoral, retromandibular, and rhytidectomy approaches are presented.

Affect and age: cross-sectional comparisons of Structure and prevalence

The self-reports of 207 young-adult (ages 18-30), 231 middle-aged (ages 31-59), and 828 older-adult (age 60 and over) Ss were used to study the structure of affect. Affects were represented by terms included in various circumplex arrays of emotions as presented by previous investigators. A set of 46 affects was subjected to exploratory analysis, and a final set of 38 affects was subjected to confirmatory factor analysis. The goodness of fit of each group's factor loadings to the hypothesized factors of positive affect, depression, anxiety-guilt, contentment, hostility, and shyness was not up to the desired .90 level, and some significant differences in factor structure were observed for each age-group comparison. There were few age differences in levels of positive affect. Depression was most frequent among younger Ss and least frequent among older Ss. Younger Ss were most often anxious and shy. Older Ss were most often content and least often hostile.

Conservation of mammalian secondary sperm receptor genes enables the promoter of the human gene to function in mouse oocytes

The human zona pellucida is an extracellular sheath composed of three major proteins (ZP1, ZP2, and ZP3) which surround the ovulated egg and mediate the initial interactions with sperm. Although fertilization is relatively species-specific and human sperm will not bind to mouse zona, there is a high degree of conservation between the coding regions of human ZP3 and mouse Zp-3 (the primary sperm receptor) genes. We now report the characterization of the human ZP2 gene and demonstrate that the sequences of its coding regions are 70% identical with those of the mouse Zp-2 (the secondary sperm receptor) gene. In addition, the first 300 bp of the 5' flanking regions of human ZP2 and mouse Zp-2 are highly conserved. This region of 5' flanking DNA contains a previously described 12-bp DNA sequence (element IV) that forms an oocyte-specific DNA-protein complex important for mouse Zp-2 and Zp-3 promoter activity. Human element IV forms a DNA-protein complex in gel mobility shift assays when incubated with human or mouse ovarian extracts. The formation of this complex is inhibited with molar excess of either human or mouse element IV sequences and is not present in extracts of testes, uterus, spleen, lung, or kidney. The human promoter region (0.3 kbp), coupled to a luciferase reporter gene and microinjected into the nuclei of 50-microns-diameter mouse oocytes, results in reporter gene activity at a level comparable to that of the homologous mouse promoter. Clustered point mutations in element IV in either the mouse or the human sequence dramatically decrease reporter gene activity. These results indicate that the similarity between mouse Zp-2 and human ZP2 genes enables the human promoter to utilize the heterologous transcription machinery in mouse oocytes. The observed transcription may involve the recognition of promoter sequences in element IV by conserved transcription factor(s).

A new approach to prenatal cystic fibrosis carrier screening

Images

Comprehensive discharge planning: a hospital-home healthcare partnership

Shorter hospital stays place new demands on the discharge planning process. A research study that evaluated discharge planning outcomes reveals a critical need for comprehensive discharge planning involving both hospital and home healthcare agencies.

The factorial generality of brief positive and negative affect measures

Confirmatory factor analysis was used to test the structure of 5-item affect rating scales designed to measure positive affect and negative affect. A proposed circumplex affect structure was the source of scales constructed to represent a cluster of positive terms, including pleasantness and activation; the negative terms represented anxiety, depression, and hostility. The hypothesized simple-structured positive and negative trait affect factors, with a moderate correlation between them, were found in all cases. Equivalent structure was confirmed for younger adults, middle-aged, and older adults of good health and above-average education. Although the hypothesized simple-structured positive and negative factors emerged for all other groups, three other tests of factor equivalence failed to be confirmed: trait and state factors in the older adult group were not identical. Factors derived from healthy and frail elders were structurally different. Variability among frail elders and variability over 30 days within the same person, when factored, also showed nonequivalence. Although the scales are extremely useful in assessing affect, comparisons across some subject groups should be made with caution.