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PubMed1985

Space nursing. A professional challenge.

The challenge is to have man living and working in a permanently based space station. Nursing is on the threshold of expanding the health care role to man's adaptation in outer space. Elements of man's physiologic and psychologic responses are involved in determining the most productive use of man and machines in the space environment. Curricular considerations for a career in space nursing are being explored. The projection of possibilities for practice of space nursing can produce effective contributions toward health care maintenance of the space station personnel. The challenge for nursing is to become a collaborating team participant in the exploration of living and working in space.

Adaptation, Physiological↗

PubMed1983

Radiation protection during space flight.

The problem of ensuring space flight safety arises from conditions inherent to space flights and outer space and from the existing weight limitations of spacecraft. In estimating radiation hazard during space flights, three natural sources are considered: the Earth's radiation belt, solar radiation, and galactic radiation. This survey first describes the major sources of radiation hazard in outer space with emphasis on those source parameters directly related to shielding manned spacecraft. Then, the current status of the safety criteria used in the shielding calculations is discussed. The rest of the survey is devoted to the rationale for spacecraft radiation shielding calculations. The recently completed long-term space flights indicate the reliability of the radiation safety measures used for the near-Earth space exploration. While planning long-term interplanetary flights, it is necessary to solve a number of complicated technological problems related to the radiation protection of the crew.

Cosmic Radiation↗

PubMedDate not supplied

Effect of right-to-left shunting on alveolar dead space.

Right-to-left shunting decreases the efficiency of carbon dioxide excretion and increases the alveolar dead space (physiological dead space minus anatomical dead space). The theoretical effects of shunting on alveolar dead space were studied, using a human blood nomogram, for different values of inspired oxygen fraction (FIO2), respiratory quotient (R), and arterial-venous oxygen content difference. An equation developed to define the relationship between alveolar dead space and shunt could be closely fitted to the nomogram data. With high levels of shunt, FIO2 and R, alveolar dead space can substantially increase above normal levels. The conditions needed for this increase are unusual but lie within the range observed in critically ill patients. A rise in dead space of this magnitude can be clinically important in the absence of effective compensatory mechanisms.

Carbon Dioxide↗

PubMed1995

Distance from the skin to the cervical epidural space.

BACKGROUND: Cervical epidural blockade provides effective regional analgesia in clinical anesthesia and pain clinics. However, the risk for performing cervical epidural block is higher than lumber epidural anesthesia. We studied the distance from the skin to the cervical epidural space to determine whether there is any relationship between patient age, height, body weight, body mass index (BMI) and the distance from the skin to the epidural space. METHODS: The study included 34 patients who underwent cervical epidural analgesic for orthopedic or plastic surgery. Cervical epidural catheterization was performed at C7-T1 intervertebral space by a midline approach with a 18-G Touhy needle. The depth of the epidural space from the skin was measured by a standard ruler. RESULTS: The distance from the skin to the cervical epidural space at C7-T1 interspace was 4.81 +/- 0.81 cm (mean +/- SD). Linear regression analysis revealed significant correlation between body weight (r2 = 0.53, p < 0.0001), BMI (r2 = 0.58, p < 0.0001) and the depth of the cervical epidural space. CONCLUSIONS: These results indicated that body weight and BMI could be a guideline for identification of epidural space during cervical epidural anesthesia.

Adolescent↗

PubMed1993

Subarachnoid spaces in infants and young children.

In computed tomography of young children, the frontal subarachnoid spaces were sometimes noted to be prominent in scans which were otherwise normal. These apparently enlarged spaces raise the suspicion of possible subdural hygromas. The objective of this study is to show the trend and variability of the intracranial subarachnoid spaces, especially the frontal subarachnoid spaces with age in children. Computed tomographic scans of 39 children up to five years of age with normal head scans were assessed for sizes of the subarachnoid spaces which were subjectively graded from I to V. Grade I is not visible while grade V is borderline enlargement. The sizes of the subarachnoid spaces were found to be more variable in those below the age of two years, with a tendency to be larger compared to older children. Based on these observations, prominent subarachnoid spaces in those below the age of two years should be considered a normal variant. A diagnosis of subdural hygroma must, therefore, be made with caution.

Brain Neoplasms↗

PubMed1996

Frequency and time domain studies of the micro-EEG from the brain extracellular space.

In these studies, recordings from the brain extracellular space of cats are considered. Macro and microelectrodes are utilized. Special studies using visual, auditory stimuli and certain drugs are done. Coherence, power phase and partial coherence spectra of wave field potentials and unit potentials are investigated. The electrographic profile of the micro electroencephalogram (EEG) and micro evoked response (ER) of the extracellular space is different than the macropotentials of the macro (EEG) and the macro (ER). The electrographic patterns of the micro (EEG) and the micro (ER) will vary with the microelectrode size, location and the variable microanatomy. There are many single neuron field potentials differentiated in space and time. In these unit fields there are varying electronic interactions varying in space and time. There are patterned inputs varying in space and time. There are fluctuating microfields distributed in overlapping layers, columns, slabs and patches and periaxonal extracellular spaces of the cerebral and cerebellar white matter. In these anatomical situations there are variable, degrees of local and general selective patterns of synchronization with variable direction, and selective spread. The extracellular space micro (EEG) shows complex and dynamic shifts of the micro (EEG) to the macro (EEG) frequencies and tuned macrofields.

Animals↗

PubMed1997

Psychosocial value of space simulation for extended spaceflight.

There have been over 60 studies of Earth-bound activities that can be viewed as simulations of manned spaceflight. These analogs have involved Antarctic and Arctic expeditions, submarines and submersible simulators, land-based simulators, and hypodynamia environments. None of these analogs has accounted for all the variables related to extended spaceflight (e.g., microgravity, long-duration, heterogeneous crews), and some of the stimulation conditions have been found to be more representative of space conditions than others. A number of psychosocial factors have emerged from the simulation literature that correspond to important issues that have been reported from space. Psychological factors include sleep disorders, alterations in time sense, transcendent experiences, demographic issues, career motivation, homesickness, and increased perceptual sensitivities. Psychiatric factors include anxiety, depression, psychosis, psychosomatic symptoms, emotional reactions related to mission stage, asthenia, and postflight personality, and marital problems. Finally, interpersonal factors include tension resulting from crew heterogeneity, decreased cohesion over time, need for privacy, and issues involving leadership roles and lines of authority. Since future space missions will usually involve heterogeneous crews working on complicated objectives over long periods of time, these features require further study. Socio-cultural factors affecting confined crews (e.g., language and dialect, cultural differences, gender biases) should be explored in order to minimize tension and sustain performance. Career motivation also needs to be examined for the purpose of improving crew cohesion and preventing subgrouping, scapegoating, and territorial behavior. Periods of monotony and reduced activity should be addressed in order to maintain morale, provide meaningful use of leisure time, and prevent negative consequences of low stimulation, such as asthenia and crew member withdrawal. Leadership roles and lines of authority need to be studied further to understand the factors leading to status leveling, leadership competition, and role confusion. Finally, the relationship between crews and ground personnel should be characterized in order to minimize the displacement of anger and tension to the outside, to counter the effects of inter-group miscommunications, and to develop support strategies that can help to counter in-group/out-group conflicts. Ground-based space simulations still have a role to play in terms of understanding the impact of these factors and ways of dealing with them. In particular, issues involving language, cultural differences, gender biases, career motivation, monotonous conditions, use of free time, leadership, lines of authority, and the relationship between crews and outside monitoring personnel need to be further characterized and examined under controlled conditions. Until such time as these factors can be studied directly in space, simulations provide an opportunity to learn more about these psychosocial issues and to plan ways of minimizing their negative consequences during actual space missions.

Career Choice↗

PubMed1988

Surgical anatomy of the anterior epitympanic space.

The structure of the anterior epitympanic space was examined in 16 temporal bones. The space showed three different structural types. In all three types the posterior boundary of the space was marked by a bony plate jutting downward and covered by a mucous membrane. No anterior boundary was found in type A (19%), the space being continuous to a widened eustachian tube orifice. In type B (31%), the space was anteriorly bounded by a mucosal fold that continued to the tensor tympani fold. In type C (50%), the space assumed the shape of a bulge extending into the bony structure and sealed at the bottom by the tensor fold. The ear surgeon is advised to be familiar with the structure of the anterior epitympanic space before intervening to remove cholesteatoma or create an anterior ventilation route.

Adult↗

PubMed2005

The history of anatomy and surgery of the preperitoneal space.

Preperitoneal (properitoneal) space is the space between the peritoneum and transversalis fascia. Bogros (1786-1825) described a triangular space in the iliac region between the iliac fascia, transversalis fascia, and parietal peritoneum. In the modern concept, this space lies between the peritoneum and posterior lamina of the transversalis fascia. In 1858, Retzius described the homonymous space, situated anterior and lateral to the urinary bladder (prevesical space). In 1975, Fowler reported that the preperitoneal fascia of the groin is distinct from the transversalis fascia. Preperitoneal herniorrhaphy may be subdivided into 2 approaches: transperitoneal and inguinal. We present herein the evolution of approaches to the preperitoneal space from use of the transperitoneal (or posterior) to use of the anterior preperitoneal and posterior preperitoneal approaches. As anatomic knowledge has increased, the evolution of laparoscopic surgery has paralleled that of open procedures.

Fascia↗

PubMed2000

Reduced aliasing artifacts using variable-density k-space sampling trajectories.

A variable-density k-space sampling method is proposed to reduce aliasing artifacts in MR images. Because most of the energy of an image is concentrated around the k-space center, aliasing artifacts will contain mostly low-frequency components if the k-space is uniformly undersampled. On the other hand, because the outer k-space region contains little energy, undersampling that region will not contribute severe aliasing artifacts. Therefore, a variable-density trajectory may sufficiently sample the central k-space region to reduce low-frequency aliasing artifacts and may undersample the outer k-space region to reduce scan time and to increase resolution. In this paper, the variable-density sampling method was implemented for both spiral imaging and two-dimensional Fourier transform (2DFT) imaging. Simulations, phantom images and in vivo cardiac images show that this method can significantly reduce the total energy of aliasing artifacts. In general, this method can be applied to all types of k-space sampling trajectories.

Algorithms↗

PubMed2000

Computer-based methods for measuring joint space and estimating erosion volume in the finger and wrist joints of patients with rheumatoid arthritis.

OBJECTIVE: This study was conducted 1) to determine the feasibility of using computer programs to measure radiographic joint space width and estimate erosion volume in the hands of patients with rheumatoid arthritis (RA), and 2) to compare the new computer-based methods with established scoring methods. METHODS: To measure the joint space width in the finger and wrist joints of RA patients, hand and wrist radiographic films were scanned using a tabletop scanner and analyzed with programs written using the "macro" capabilities of NIH Image software. Estimation of erosion volume was determined by utilizing gray-scale intensity to calibrate bone density units per mm3, which made possible comparisons between the erosions and noneroded, anatomically similar sites. RESULTS: In 3 sets of duplicate measurements of joint space width on 79, 48, and 48 finger and wrist joints, the mean absolute deviation from the mean of the 2 measurements was 0.036 mm (SD 0.034), 0.032 mm (SD 0.049), and 0.021 mm (SD 0.016), respectively. Joint space measurements and scoring of joint space narrowing both demonstrated a difference between active treatment and placebo in an old trial set on gold therapy (P = 0.03 and P = 0.01, respectively). Two repeated measurements of bone density units in the bones of 3 different hands differed from the mean of the measurement by 2.29-4.04%. In 2 experiments, estimates of erosion volume showed a greater difference between gold therapy and placebo than did erosion scores in the trial set (P = 0.049 and P = 0.016 versus P = 0.27). CONCLUSION: Computer-based methods for measuring finger and wrist joint spaces and estimating erosion volume in patients with RA agree with the results of radiographic scoring of erosions and joint space narrowing.

Arthritis, Rheumatoid↗

PubMed1987

Paravascular cells in endosteal spaces of alveolar bone contribute to periodontal ligament cell populations.

Endosteal spaces of alveolar bone communicate with the periodontal ligament and may contribute to its cell populations. We examined cell proliferation and migration in endosteal spaces and in the periodontal ligament contiguous with these spaces. Radioautographs of mouse mandibular molar were prepared from animals pulse-injected with 3H-Tdr and sacrificed in groups of 22 mice each at 1 h, 1, 3, and 7 d after labeling. Cell counts, labeling indices, grain counts, and progenitor cell ratios were determined. The data indicate that endosteal spaces are enriched with 3H-Tdr-labeled progenitor cells whose progeny rapidly migrate out of the compartment. The periodontal ligament contiguous with the endosteal spaces exhibited 5 times as many labeled cells as other sites in this tissue. Thickened areas of cementum were coincident with the openings of endosteal spaces in over 64% of observations. The data are consistent with the hypothesis that cells migrate from endosteal spaces into the periodontal ligament and there express the phenotype for osteoblasts or cementoblasts.

Alveolar Process↗

PubMed2003

Age and sex differences in hip joint space among asymptomatic subjects without structural change: implications for epidemiologic studies.

OBJECTIVE: The prevalence of hip osteoarthritis (OA) increases significantly with age. Although it is not clear whether joint space loss at the hip is a feature of normal aging or a reflection of the OA process, epidemiologic criteria for OA are based on narrowing alone. The aim of this study was to determine whether changes in joint space width occur with age, and whether there are sex differences, in asymptomatic subjects without hip OA. METHODS: We identified a total of 1,806 subjects who had undergone intravenous urography between 1994 and 1996 and sent a questionnaire to the 1,527 of these subjects who were alive in 1998; 1,031 replies (68%) were received. All radiographs were read by an observer blinded to age, sex, and pain status. Individual radiographic features of OA (narrowing, osteophyte, sclerosis, and cysts) were graded, and an overall qualitative grade was allocated, according to a standard atlas. Minimum joint space width (JSW) was measured by metered caliper to within 0.1 mm. A total of 276 women (mean age 63 years) and 257 men (mean age 64 years) were identified who had never had hip pain (defined as having ever had pain on most days for at least 1 month) and who had no evidence of either joint space narrowing or osteophyte (grade 0, no structural changes). The minimum JSW in either hip was tabulated according to age. RESULTS: JSW measurement was reproducible (95% confidence limits of agreement) to within +/-0.5 mm. At all ages, men had larger JSW than women (3.85 mm in women, 4.19 mm in men, mean difference 0.34 mm; 95% confidence interval [95% CI] 0.24, 0.44). A significant decline in JSW with age was seen in women, with a mean difference between ages 45-54 and 75-84 years of 0.36 mm (95% CI 0.15, 0.58; P = 0.001). No significant change in JSW with age was seen in men (mean difference 0.16 mm; 95% CI -0.11, 0.43). Analysis of an additional 64 women and 61 men who were without hip pain and had overall qualitative grade 1-2 changes gave similar results. Implementing these results to alter the threshold for definition of hip OA in women from < or =2.5 mm to < or =2.2 mm reduced the prevalence of hip OA from 10.6% to 5.6%. CONCLUSION: These sex differences in joint space have significant implications in terms of the major emphasis on joint space narrowing in definitions of hip OA. Women also have a significant progressive decline in joint space with age that is not seen in men. This suggests that in women, loss of cartilage may be an age-related phenomenon that is independent of other aspects of structural change. Consideration should be given to the development of sex-specific definitions of hip "OA."

Age Factors↗

PubMed2003

What arteries are detectable in the precarinal space on contrast-enhanced CT?

Although the precarinal space is critical in the interpretation of computed tomography (CT) of the thorax, vascular structures within the space have not been well documented. The aim of this study was to investigate vascular structures in the precarinal space that are detectable with contrast-enhanced CT scans. Contrast-enhanced CT chest scans from 90 patients aged 17-78 years (41 male, 49 female) were analyzed retrospectively. Twenty-two cadavers aged 54-93 years (13 male, 9 female) were used for gross anatomic study. We found that 9 of 90 cases of the contrast-enhanced CT scans had vessel-like structures detectable in the precarinal space, located primarily anterior to the right main bronchus. Single or double arteries were identified in the precarinal space of 19 cadavers. Thirteen of the 23 arteries observed were the right bronchial artery and 10 were the left bronchial artery. In two cadavers, a single right bronchial artery (2.5 and 4.0 mm in diameter), which could have been detected with contrast-enhanced CT, originated from the aortic arch and the root of the left subclavian artery and coursed in the precarinal space. Based on the variation in the location and size of the bronchial arteries observed in this study, we suggest that vascular structures are detectable in the precarinal space with contrast-enhanced CT, particularly anterior to the right main bronchus.

Adolescent↗

PubMed2006

Direct versus mediated through-space magnetic interactions: A first principles, bottom-up reinvestigation of the magnetism of the pyridyl-verdazyl:hydroquinone molecular co-crystal.

The mechanism of the magnetic interaction in the pyridyl-verdazyl radical:hydroquinone (pyvd:hq) molecular co-crystal is important as it has been suggested to originate by a unique "mediated through-space" magnetic interaction. This interaction was proposed to magnetically connect two nonadjacent pyridyl-verdazyl radicals within a pi stack, where adjacent radicals pile up in a head-over-tail orientation. The connection is made through a third radical sitting between the previous two mediated radicals. Given the relevance of this proposal, we decided to reinvestigate the magnetic properties of this co-crystal by using our recently proposed first-principles "bottom-up" procedure. Based on B3LYP/6-31+G(d) and CASSCF(6,6)/6-31+G(d) calculations (the results of which are identical to those provided by CASSCF(10,10)/6-31+G(d) calculations), we have computed the microscopic J(AB) values for all direct through-space magnetic interactions between nearby pyridyl-verdazyl radicals. The magnetic interactions give rise to two dominant values of similar strength: -56 and -54 cm(-1) at the B3LYP level, which are calculated as -38 and -31 cm(-1) at the CASSCF(6,6) and CAS(10,10) levels (all other interactions being smaller than |1| cm(-1)). The dominant interactions correspond to the direct through-space interaction between two adjacent radicals of a pi stack. The crystal also exhibits a radical-mediated through-space interaction of -0.31 cm(-1) between two nonadjacent radicals of a pi stack. The direct through-space magnetic interactions are two orders of magnitude larger than the mediated through-space interaction. Thus, first-principles calculations do not support a mediated through-space mechanism to explain the magnetism of the pyvd:hq co-crystal. The magnetic topology generated by the two dominant antiferromagnetic interactions in the pyvd:hq co-crystal consists of one-dimensional (1D) alternating chains (interacting very weakly along the b and c axes). By using this topology, the computed macroscopic magnetic susceptibility curve reproduces the experimental one properly. This first-principles bottom-up description of the magnetism in the pyvd:hq co-crystal differs in some fundamental aspects from that previously proposed in the literature.

Journal Article↗

PubMed1989

Role of commissural projections in the representation of bilateral auditory space in the barn owl's inferior colliculus.

The central nucleus of the barn owl's inferior colliculus (ICc) contains a representation of both the ipsilateral and contralateral auditory hemifields. The representation of ipsilateral space is found in the "core" of the ICc, a subdivision defined by the terminal field of nucleus laminaris, the avian analogue of the medial superior olivary nucleus. The representation of contralateral space is found in the lateral portion of the "shell" of the ICc. The shell surrounds the core and is defined by the terminal field of the nucleus angularis, one of the cochlear nuclei. The representation of ipsilateral space in the core of the ICc may be accounted for by the crossed projection from the nucleus laminaris because most of the nucleus laminaris is devoted to a representation of contralateral space. We present evidence to suggest that the representation of contralateral space is due to a commissural projection from the core of one side to the lateral shell of the opposite side. Injection of horseradish peroxidase (HRP) into the lateral portion of the ICc shell produced retrogradely labeled somata in the core of the opposite side. Injection of tritiated proline into the core produced anterograde label confined to the lateral shell, thus confirming the observations made with HRP. Thus, for example, the left ICc core, which contains predominantly a representation of the left hemifield, innervates the right lateral shell, endowing it with a representation of the left, or contralateral hemifield. The representation of contralateral space in the lateral shell is ultimately conveyed to the external nucleus of the inferior colliculus where it contributes the horizontal axis to a two-dimensional map of space.

Acoustic Stimulation↗

PubMedDate not supplied

High b-value q-space analyzed diffusion-weighted MRS and MRI in neuronal tissues - a technical review.

This review deals with high b-value q-space diffusion-weighted MRI (DW-MRI) of neuronal tissues. It is well documented that at sufficiently high b-values (and high q-values) neuronal water signal decay in diffusion experiments is not mono-exponential. This implies the existence of more than one apparent diffusing component or evidence for restriction. The assignment of the different apparent diffusing components to real physical entities is not straightforward. However, the apparent slow diffusing component that was found to be restricted to a compartment of a few microns, if originating mainly from a specific pool and if assigned correctly, may potentially be used to obtain more specific MR images with regard to specific pathologies of the CNS. This review examines the utility of analyzing high b-value diffusion MRS and MRI data using the q-space approach introduced by Callaghan and by Cory and Garroway. This approach provides displacement probability maps that emphasize, at long diffusion times, the characteristics of the apparent slow diffusing component. Examples from excised spinal cord, where the experimental conditions for which the q-space analysis of MR diffusion data was developed can be met or approached will be presented. Then examples from human MS patients, where q-space requirement for the short gradient pulse is clearly violated, are presented. In the excised spinal cord studies, this approach was used to study spinal cord maturation and trauma, and was found to be more sensitive than other conventional methods in following spinal cord degeneration in an experimental model of vascular dementia (VaD). High b-value q-space DWI was also recently used to study healthy and MS diseased human brains. This approach was found to be very sensitive to the disease load in MS, compared with other conventional MRI methods, especially in the normal appearing white matter (NAWM) of MS brains. Finally, the potential diagnostic capacity embedded in high b-value q-space analyzed diffusion MR images is discussed. The potentials and caveats of this approach are outlined and experimental data are presented that show the effect of violating the short gradient pulse (SGP) approximation on the extracted parameters from the q-space analysis.

Algorithms↗

PubMed2000

Geometric and Topological Analysis of Three-Dimensional Porous Media: Pore Space Partitioning Based on Morphological Skeletonization.

This article presents a versatile, rigorous, and efficient methodology for extracting various geometric and topological parameters of 3D discrete porous media. The new approach takes advantage of the morphological skeleton of the pore structure-a lower dimensional representation of the pore space akin to the topological "deformation retract". The skeleton is derived by a fully parallel thinning algorithm that fulfils two essential requirements: it generates a medial axis and preserves the connectivity of the pore space. Topological analysis is accomplished by classifying all skeleton points as node or link (branch) points according to the concept of lambda-adjacency in 3D discrete space. In this manner, node coordination number and link length distributions are directly obtained from the skeleton. Pore necks (throats) are identified through a search for minima in the hydraulic radius of individual pore space channels outlined by skeleton links. In addition to the determination of the size distribution of the constrictions (pore necks) that control nonwetting phase invasion, improved estimates of the distributions of effective hydraulic and electric conductivity of individual pore space channels are obtained. Furthermore, erection of planes at the location of pore necks results in partitioning of the pore space into its constituent pores. This enables the characterization of the pore space in terms of a pore volume distribution. The new methodology is illustrated by application to a regular cubic pore network and irregularly shaped 2D and 3D pore networks generated by stochastic simulation. In the latter case, important new results are obtained concerning the sensitivity of geometric and topological properties of the microstructure to the parameters of stochastic simulation, namely, the porosity and correlation function. It is found that model porous media reconstructed from the same porosity and correlation function can exhibit marked differences in geometry and connectivity, which correlate with differences in specific surface area. Copyright 2000 Academic Press.

Journal Article↗