SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
On the basis of their findings and the data published in the literature the authors review the main results of investigations related to the hygienic maintenance of manned space flights. The paper presents the major problems in this field that need to be resolved in order to maintain adequate environments in space cabins.
Inferior alveolar nerve denervation causes appreciable decreases in the distribution of epithelial rests of Malassez. To explore roles of the Malassez epithelium, we attempted to evaluate possible changes in dento-alveolar tissues surrounding this epithelium by experimental denervation. We found that denervation led to dento-alveolar ankylosis with a decrease in the width of the periodontal spaces. Interestingly, with regeneration of the Malassez epithelium 10 weeks after the denervation, the periodontal space width showed a correspondingly significant increase. These findings suggest that the Malassez epithelium may be involved in the maintenance of periodontal space and that sensory innervation might be indirectly associated with it. In addition, it is of interest that denervation activated root resorption of the coronal root surface and that the consequently resorbed lacunae were repaired by cellular cementum. It is suggested that Malassez epithelium may negatively regulate root resorption and induce acellular cementum formation.
NASA is developing a Health Maintenance Facility to provide medical equipment and supplies requisite for the Space Station to be launched in the late 1990s. An essential component of this medical facility is a computerized Medical Decision Support System which will expedite medical officers' efforts to maintain the crew's health. The computerized system includes four major functions: 1. A data collection and storage system with a self-contained medical expert scheme for performing treatment protocols. The expert system has 'data driven' and 'time driven' capabilities to facilitate automatic decision-making functions. 2. An integrated medical record and medical 'reference' information management component. 3. An inventory management system for medical supplies and pharmaceuticals. 4. Video, audio, and data communications between the medical officer in the Space Station and ground-based medical personnel. This paper discusses the design of such computerized data collection, communications and expert medical systems as will be developed for use in a Space Station Health Maintenance Facility.
BACKGROUND: Multiple drug immunosuppression has allowed the near elimination of rejection, but without commensurate improvements in longterm graft survival and at the cost of quality of life. We have suggested that transplantation outcomes can be improved by modifying the timing and dosage of immunosuppression to facilitate natural mechanisms of alloengraftment and acquired tolerance. STUDY DESIGN: Two therapeutic principles were applied for kidney transplantation: pretransplant recipient conditioning with antilymphoid antibody preparations (Thymoglobulin [Sangstat] or Campath [ILEX Pharmaceuticals]), and minimal posttransplant immunosuppression with tacrolimus monotherapy including "spaced weaning" of maintenance doses when possible. The results in Thymoglobulin- (n = 101) and Campath-pretreated renal transplantation recipients (n = 90) were compared with those in 152 conventionally immunosuppressed recipients in the immediately preceding era. RESULTS: Spaced weaning was attempted in more than 90% of the kidney transplant recipients after pretreatment with both lymphoid-depleting agents, and is currently in effect in two-thirds of the survivors. Although there was a much higher rate of acute rejection in the Thymoglobulin-pretreated recipients than in either the Campath-pretreated or historic control recipients, patient and graft survival in both lymphoid depletion groups is at least equivalent to that of historic control patients. In the Thymoglobulin-conditioned patients for whom followups are now 24 to 40 months, chronic allograft nephropathy (CAN) progressed at the same rate as in historic control patients. Selected patients on weaning developed donor-specific nonreactivity. CONCLUSIONS: After lymphoid depletion, kidney transplantation can be readily accomplished under minimal immunosuppression with less dependence on late maintenance immunosuppression and a better quality of life. Campath was the more effective agent for pretreatment. Guidelines for spaced weaning need additional refinement.
Osteoarthritis of the thumb carpal metacarpal joint is effectively managed by complete excision of the trapezium or excision of the distal half of the trapezium with maintenance of the space by insertion of interposition tendinous material from palmaris longus or flexor carpi radialis. The more recent modification of partial trapezium excision has improved pinch strength and maintenance of thumb length and so has enhanced the final results. Carpal metacarpal ligament reconstruction is demonstrated because it is occasionally necessary.
Since the Space Station Health Maintenance Facility can house only a relatively limited quantity of supplies and equipment, the decisions about what should be included must be based on documented research. In this study, Space Station medical care priorities were determined by a medical impact analysis of two analog populations, U.S. Army and U.S. Navy personnel. Diseases and injuries in the International Classification of Disease, 9th Revision, Clinical Modification (ICD-9-CM) were ranked, using a Medical Impact Score (MIS) combining modified incidence rate and a function of disease outcome. The validity of the analysis method was tested by measuring rank order correlation between the two analog populations. Despite virtually identical age and sex distributions, Army and Navy incidence rates differed significantly for half of the ICD-9-CM categories, p less than 0.05. Disability rates differed for 76%, p less than 0.05. Nevertheless, Army and Navy MIS rank orders for categories and sections were not significantly different, p less than 0.001. In critical ways, the Space Station will be a safer environment than Earth. Cardiac events, musculoskeletal injuries, affective psychoses, and renal calculi were among the highest scoring categories.
A large number of potential regulatory mechanisms have been described which may be involved in the control of cell function in the periodontium. In this review, soluble effector molecules which may regulate normal cell turnover and which may control the maintenance of the periodontal space are considered. There is evidence for the involvement of growth factors including EGF, PDGF, FGFs, IGF I & II and TGF-beta in these processes. The role of bone morphogenetic proteins (BMPs) in periodontal turnover is of considerable interest as they appear to be able to regulate all stages of this process from specifying cell commitment to regulating differentiated cell function. Empirical evidence suggests the importance of mechanical stimulation in controlling the maintenance of the periodontal ligament space. The wide range of effects of mechanical stimulation are briefly reviewed and the central role of prostaglandins is considered. Recent evidence suggests the involvement of nitric oxide (NO) in the regulation of mineralised tissue function, and the potential role of NO in maintenance of the ligament space is considered. Further studies are required which address the interactions between all of these mechanisms in order to determine the key factors which may control periodontal cell function. For the future an understanding of these interactions has the potential to lead to important clinical developments in periodontal and orthodontic therapy.
The twelve months since IAF 2000 have been perhaps the most exciting, challenging and rewarding months for Canada since the beginning of our participation in the International Space Station program in 1984. The highlight was the successful launch, on-orbit check out, and the first operational use of Canadarm2, the Space Station Remote Manipulator System, between April and July 2001. The anomalies encountered and the solutions found to achieve this success are described in the paper. The paper describes, also, the substantial progress that has been made, during the twelve months since IAF 2000, by Canada as it continues to complete work on all flight-elements of its contribution to the International Space Station and as we transition into real-time Space Station operations support and Canadian utilization. Canada's contribution to the International Space Station is the Mobile Servicing System (MSS), the external robotic system that is key to the successful assembly of the Space Station, the maintenance of its external systems, astronaut EVA support, and the servicing of external science payloads. The MSS ground segment that supports MSS operations, training, sustaining engineering, and logistics activities is reaching maturity. The MSS Engineering Support Center and the MSS Sustaining Engineering Facility are providing real-time support for on-orbit operations, and a Canadian Payloads Telescience Operations Center is now in place. Mission Controllers, astronauts and cosmonauts from all Space Station Partners continue to receive training at the Canadian Space Agency. The Remote Multi Purpose Room, one element of the MSS Operations Complex, will be ready to assume backroom support in 2002. Canada has completed work on identifying its Space Station utilization activities for the period 2000 through 2004. Also during the past twelve months the CSA drafted and is proceeding with the approval of a Canadian Space Station Commercialization Policy. Canadian astronauts have now participated in three ISS assembly missions--Julie Payette on STS-96, Marc Garneau on STS-97, and Chris Hadfield on STS-100 in April 2001 during which he performed Canada's first EVA and the successful installation of the Space Station Remote Manipulator System.
Space offers the occupational health nurse a unique occupational environment and many challenges. Zero gravity and severe limitations on working space will require many changes in methods of operation. The health maintenance facility within the space station will not be equipped to deal with all conceivable emergencies, but personnel will be able to diagnose and treat injuries and illnesses which are most likely to occur and are easily treated. Occupational health nurses are uniquely qualified to meet NASA's health maintenance facility objectives.
In 5 newborn infants with severe valvular aortic stenosis, left ventricular angiocardiography revealed conspicuous pathologic-morphologic findings consisting of a fine network of contrast medium opacification in the region of the posterior wall. Subsequently performed histologic examination of tissue removed from the involved regions showed, in addition to endocardial fibroelastosis, two structures which were assumed to be the morphologic substrates for the unusual distribution of contrast medium. On the one hand, antler-like spaces with a well-demarcated lining of fibroelastic tissue, similar to the thickened endocardium, were found in the inner half of the left ventricular wall connected to the lumen of the left ventricle through bottle-necked communications. On the other hand, oval or oblong lumina, substantially larger in caliber than capillaries but showing only a single endothelial layer could be demonstrated. With the sectioning technique employed, anastomoses of the latter spaces with the left ventricle or the previously mentioned system of spaces could not be established. The cause of the development or maintenance of these sinusoidal spaces may be attributable to the elevated diastolic left ventricular pressure, while the elevated systolic pressure may have been a decisive etiologic factor for the endocardial fibroelastosis. Whether the intratrabecular spaces represent persistent embryonic myocardial sinusoids cannot be differentiated unequivocally. In support of the stated contentions, however, are other results indicating that the extent of structural changes in the ventricular wall increases proportionately with the duration of existence of the obstructive lesion in the embryonic period.
The problem is considered of using the PROGRESS transport spacecraft, which will deliver the payload on the ISS, as a free flying platform for realization of space experiments. For maintenance of the ISS 5-6 PROGRESS flights per year are planned. Usually after delivery of the payload the PROGRESS undocks from the ISS and burns down in the Earth atmosphere. However, the operating conditions of its onboard systems allow to prolong operation and to make free flight near to the station and repeatedly to be docked to it. It is offered to use this possibility for performing experiments on Material Science.
Heterocysts are terminally differentiated cells of some filamentous cyanobacteria that fix nitrogen for the entire filament under oxic growth conditions. Anabaena variabilis ATCC 29413 is unusual in that it has two Mo-dependent nitrogenases; one, called Nif1, functions in heterocysts, while the second, Nif2, functions under anoxic conditions in vegetative cells. Both nitrogenases depended on expression of the global regulatory protein NtcA. It has long been thought that a product of nitrogen fixation in heterocysts plays a role in maintenance of the spaced pattern of heterocyst differentiation. This model assumes that each cell in a filament senses its own environment in terms of nitrogen sufficiency and responds accordingly in terms of differentiation. Expression of the Nif2 nitrogenase under anoxic conditions in vegetative cells was sufficient to support long-term growth of a nif1 mutant; however, that expression did not prevent differentiation of heterocysts and expression of the nif1 nitrogenase in either the nif1 mutant or the wild-type strain. This suggested that the nitrogen sufficiency of individual cells in the filament did not affect the signal that induces heterocyst differentiation. Perhaps there is a global mechanism by which the filament senses nitrogen sufficiency or insufficiency based on the external availability of fixed nitrogen. The filament would then respond by producing heterocyst differentiation signals that affect the entire filament. This does not preclude cell-to-cell signaling in the maintenance of heterocyst pattern but suggests that overall control of the process is not controlled by nitrogen insufficiency of individual cells.
The capacity of naturally breeding western fence lizards (Sceloporus occidentalis biseriatus) to discriminate and respond to conspecific and control chemical cues was examined. Lizards were presented with markings and exudates of male and female donors, as well as cologne (a pungency control) and water, in a successive discrimination procedure. Behavioral actions quantified after exposure to the different chemical cue types included lingual extrusions (tongue flicks and substrate licks), rapid nasal inhalations, and the performance of push-up visual displays. Initial latencies to lingual investigation of the different extracts and markings also were recorded as a measure of the extent to which nasal olfaction would switch on the tongue-Jacobson's organ (vomeronasal olfactory) system. Although no sex differences in total levels of response were noted, males and females exhibited significant lingual discriminations equally to exudates collected from male or female conspecifics. Push-up visual displays also were noted in response to conspecific markings. Cologne-marked surfaced, however, elicited nonsignificant levels of lingual investigation and push-up displaying. Latencies to initial tongue flicks, but not substrate licks, were significantly shorter when any material other than water was present. Therefore, as suggested by Cowles and Phelan ('58), nasal olfaction may indeed be more of a "quantitative," distance sensing system that responds to the presence of any pungent substance by initiating further investigation via the tongue-Jacobson's organ system. The latter appears to be more "qualitative," or discriminating, as indexed by relatively greater levels of lingual investigation of conspecific markings than cologne. No differences were noted in rapid nasal inhalation activity. The results suggest that pheromone markings, along the ground or other surfaces, may be important to spacing and territorial maintenance in nature. This could occur through direct pheromone effects on signal recipients, or indirectly, through the stimulation of increased push-up activity, which could make lizards more visible to one another.
Treatment of patients suffering from severe head injury is so far restricted to general procedures, whereas specific pharmacological agents of neuroprotection including hypothermia have not been found to improve the outcome in clinical trials. Albeit effective, symptomatic measures of the preclinical rescue of patients (i.e. stabilization or reestablishment of the circulatory and respiratory system) or of the early clinical care (e.g. prompt diagnosis and treatment of an intracranial space occupying mass, maintenance of a competent circulatory and respiratory system, and others) by and large constitute the current treatment based on considerable organizational and logistical efforts. These and other components of the head injury treatment are certainly worthwhile of a systematic analysis as to their efficacy or remaining deficiencies, respectively. Deficits could be associated with delays of providing preclinical rescue procedures (e.g. until intubation of the patient or administration of fluid). Delays could also be associated in the hospital with the diagnostic establishment of intracranial lesions requiring prompt neurosurgical intervention. By support of the Federal Ministry of Education and Research and under the auspices of the Forschungsverbund Neurotraumatology, University of Munich, a prospective system analysis was carried out on major aspects of the pre- and early clinical management at a population based level in patients with traumatic brain injury. Documentation of pertinent data was made from August 1998 to July 1999 covering a catchment area of Southern Bavaria (5.6 mio inhabitants). Altogether 528 cases identified to suffer from severe head injury (GCS < or = 8 or deteriorating to that level within 48 hrs) were enrolled following admission to the hospital and establishment of the diagnosis. Further, patients dying on the scene or during transport to the hospital were also documented, particularly as to the frequency of severe head injury as underlying cause of mortality. The analysis included also cases with additional peripheral trauma (polytrauma). The efficacy of the logistics and organization of the management was studied by documentation of prognosis-relevant time intervals, as for example until arrival of the rescue squad at the scene of an accident, until intubation and administration of fluid, or upon hospital admission until establishment of the CT-diagnosis and commencement of surgery or transfer to the intensive care unit, respectively. The severity of cases studied in the present analysis is evident from a mortality of far above 40% of cases admitted to the hospital, which was increased by about 20% when including prehospital mortality. The outcome data notwithstanding, the emerging results demonstrate a high efficacy of the pre- and early clinical management, as indicated by a prompt arrival of the rescue squad at the scene, a competent prehospital and early clinical management and care, indicative of a low rate of avoidable complications. It is tentatively concluded on the basis of these findings that the patient prognosis is increasingly determined by the manifestations of primary brain damage vs. the development of secondary complications.
Four hundred and ninety-nine cases of osteo-articular tuberculosis have been analysed with special emphasis on the "unusual" presentation. Sclerotic bone reaction in association with active tuberculous osteitis is not at all uncommon and may occur in any affected bone. Maintenance of disc spaces with tuberculous spondylitis is not uncommon. Periosteal reactions, often very gross, occur commonly both in multicystic tuberculosis as well as in isolated lesions. Multiple bone involvement occurred in 8.2% of this series. Tomography delineates the total extent of involvement especially in central involvement of vertebral bodies. Healed tuberculosis may give rise to block vertebrae indistinguishable from the congenital type except for the absence of waisting at the level of fusion.
The gene hetN encodes a putative oxidoreductase that is known to suppress heterocyst differentiation when present on a multicopy plasmid in Anabaena sp. PCC 7120. To mimic the hetN null phenotype and to examine where HetN acts in the regulatory cascade that controls heterocyst differentiation, we replaced the native chromosomal hetN promoter with the copper-inducible petE promoter. In the presence of copper, heterocyst formation was suppressed in undifferentiated filaments. When hetN expression was turned off by transferring cells to media lacking copper, the filaments initially displayed the wild-type pattern of single heterocysts but, 48 h after the induction of heterocyst formation, a pattern of multiple contiguous heterocysts predominated. Suppression of heterocyst formation by HetN appears to occur both upstream and downstream of the positive regulator HetR: overexpression of hetN in undifferentiated filaments prevents the wild-type pattern of hetR expression as well as the multiheterocyst phenotype normally observed when hetR is expressed from an inducible promoter. Green fluorescent protein fusions show that the expression of hetN in wild-type filaments normally occurs primarily in heterocysts. We propose that HetN is normally involved in the maintenance of heterocyst spacing after the initial heterocyst pattern has been established, but ectopic expression of hetN can also block the initial establishment of the pattern.
Cryopreservation of spermatozoa, oocytes and embryos, as well as somatic cells or cell lines for cloning from cells, are all options for the long-term storage of unique genotypes and endangered species. Spermatozoal cryopreservation and storage currently require liquid nitrogen or ultralow refrigeration-based methods for long- or short-term storage, which requires routine maintenance and extensive space requirements. The preservation of stem cells also has strict requirements for long-term storage to maintain genetic integrity. Dessicated (lyopreserved) sperm and stem cells will provide an unprecedented type of long-term storage without the need for expensive and burdensome cryogenic conditions. Experiments were conducted to determine an effective intracellular concentration of the lyoprotectant trehalose. High-pressure liquid chromatography studies revealed that trehalose can be incorporated into mature sperm cells as well as spermatogonial stem cells from rhesus monkeys. In addition, using fourier transform infrared spectroscopy, we determined that thermotropic phase transitions for fresh ejaculates from rhesus monkey and stallion sperm occurred at 10-15, 33-37 and 55-59 degrees C. Preliminary studies in our laboratory have indicated that spermatogonial stem cells can be dried to <3 g g(-1) water and maintain viability following rehydration. Studies in our laboratory have provided preliminary results suggesting that the desiccated storage of sperm and spermatogonial stem cells may be a viable alternative to conventional cryopreservation.
The study attempted to distinguish avoidant vs. secure infants at 1 year from 4-month infant behavior only, during a face-to-face play interaction with the mother. Thirty-five 4-month-old infants were coded second by second for infant gaze, head orientation, facial expression and self-touch/mouthing behavior. Mother behavior was not coded. At 1 year, 27 of these infants were classified as secure (B), and 8 as avoidant (A) attachment in the Ainsworth Strange Situation. Compared with the B infant, the future A infant spent less time paying 'focused' visual attention (a look of a minimum 2 seconds duration) to the mother's face. Only if the A infant engaged in self-touch/mouthing behavior did its focused visual attention match that of the B. Markovian t to t+1 transition matrices then showed that both for future A and for future B infants, focused visual attention on the mother constrained the movements of the head to within 60 degrees from center vis-à-vis, defining head/gaze co-ordination within an attentional-interpersonal space. However, infant maintenance of head/gaze co-ordination was associated with self-touch/mouthing behavior for the A infant but not the B. Positive affect was associated with a disruption of head/gaze co-ordination for the A but not the B. Whereas the B had more variable facial behavior, potentially providing more facial signaling for the mother, the A had more variable tactile/mouthing behavior, changing patterns of self-soothing more often. Thus, infants classified as A vs. B at 12 months showed different behavioral patterns in face-to-face play with their mothers as early as 4 months.