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PubMed2006

Structural and functional features and significance of the physical linkage between ER and mitochondria.

The role of mitochondria in cell metabolism and survival is controlled by calcium signals that are commonly transmitted at the close associations between mitochondria and endoplasmic reticulum (ER). However, the physical linkage of the ER-mitochondria interface and its relevance for cell function remains elusive. We show by electron tomography that ER and mitochondria are adjoined by tethers that are approximately 10 nm at the smooth ER and approximately 25 nm at the rough ER. Limited proteolysis separates ER from mitochondria, whereas expression of a short "synthetic linker" (<5 nm) leads to tightening of the associations. Although normal connections are necessary and sufficient for proper propagation of ER-derived calcium signals to the mitochondria, tightened connections, synthetic or naturally observed under apoptosis-inducing conditions, make mitochondria prone to Ca2+ overloading and ensuing permeability transition. These results reveal an unexpected dependence of cell function and survival on the maintenance of proper spacing between the ER and mitochondria.

Amino Acid Sequence↗

PubMed1992

In vitro definition of the yeast RNA polymerase I promoter.

The structure of the ribosomal gene promoter from Saccharomyces cerevisiae has been analyzed in a whole cell in vitro extract. The promoter contains at least two essential domains, an upstream domain located at the 5' boundary near position -150 and a core promoter domain around the site of transcription initiation at +1. The upstream domain augments transcription in vitro but is not absolutely required. Maintenance of correct spacing between the two domains is critical. The in vitro analysis agrees well with prior in vivo analysis and it appears that the yeast promoter has a structure very similar to that of vertebrate ribosomal gene promoters.

Base Sequence↗

PubMed2006

Attachment systems for implant retained overdentures: a literature review.

This article presents a comparison between different attachment systems used to retain and support maxillary and mandibular overdentures in completely edentulous patients. A literature review based on a MEDLINE search limited to English-language articles published from 1988 to the present was performed, and a large number of attachments available in the dental market were reviewed with regard to several factors, including: (1) implant survival rate, (2) marginal bone loss, (3) soft tissue complications, (4) retention, (5) stress distribution, (6) space requirements, (7) maintenance complications, and (8) patient satisfaction. These factors are considered essential for the successful outcome and good long-term prognosis of the prostheses. Selection criteria previously published in the literature are discussed as well. Product names and manufacturers are mentioned only if related to attachment systems, as they are cited in the original articles.

Alveolar Bone Loss↗

PubMed2001

Effects of ionizing radiation on progressive experimental renal disease: a hemodynamic approach.

In order to evaluate the progression of renal disease, Munich-Wistar rats were submitted to 5/6 nephrectomy and given whole-body x- or gamma-irradiation with or without remnant kidney protection or were submitted only to remnant kidney irradiation. All groups received a single 6-Gy dose immediately after surgery. Whole-kidney function, glomerular hemodynamics, 24-hour proteinuria and histopathology were assessed 60 days after surgery and irradiation. The irradiated nephrectomized animals presented whole-kidney function parameters comparable to those of normal rats. In addition, they were less hypertensive and had higher hematocrit. They showed glomerular hyperfiltration and hypertension even greater than their respective nephrectomized controls. However, the interrelations among the glomerular filtration determinants were somewhat different in irradiated animals. Their 24-hour proteinuria was significantly lower and the sclerosis index and tubulointerstitial injury score were markedly smaller. Among irradiated animals, the worst sclerosis index was observed in those with a shielded remnant kidney and the best in those without protection of the remnant kidney. This led us to speculate about a possible influence of resident mesangial cells on the early events following renal mass ablation and on the maintenance of subsequent physiopathologic changes. Therefore, radiation undoubtedly provoked a beneficial change in the course of renal disease when the renal mass ablation model was employed. Many factors could have contributed to this favorable feature including lower levels of systemic arterial pressure, less increment in DeltaP, diminished proteinuria, and maintenance of tubulointerstitial space integrity. Our data also suggest that development of glomerulosclerosis seems to be determined by events occurring immediately after injury.

Animals↗

PubMed1975

Effect of coronary blood flow on glycolytic flux and intracellular pH in isolated rat hearts.

The rate of coronary blood flow was varied in isolated working rat heart preparations to determine its influence on the rate of glocose utilization, tissue high-energy phosphates, and intracellular pH. A 60% reduction in coronary blood flow resulted in a 30% reduction in oxygen consumption, an accelerated rate of glusoe utilization, lower tissue levels of high-energy phosphate, and higher tissue levels of lactate and H+. Ventricular performance deteriorated as reflected by a decrease in heart rate and peak systolic pressure. Further reductions in coronary blood flow resulted in inhibition of glycolysis, a greater decrease in tissue levels of high-energy phosphates, and higher tissue levels of both lactate and H+. These changes in glycolytic flux, tissue metabolites, and ventricular performance were proportional to the degree of restriction in coronary blood flow. The importance of coronary blood flow and washout of the interstitial space in the maintenance of accelerated glycolytic flux in oxygen-deficient hearts is emphasized. It is concluded that acceleration of ATP production from glycolysis can occur only in the marginally ischemic tissue in the peripheral area of tissue supplied by an occluded artery. The central area of tissue which receives a low rate of coronary blood flow will have a reduced rate of ATP production due to both a lack of oxygen and an inhibition of glycolysis.

Adenosine Triphosphate↗

PubMed1992

The orthodontic/restorative interface. Restorative procedures to aid orthodontic treatment.

Restorative procedures which complement orthodontic treatment and which may be carried out by the orthodontist are summarized. The importance of planning, with the restorative requirements in mind and the maintenance of prepared space (individual tooth or abutment positions) in all three planes of space during the period of retention, is described. The importance of liaison regarding the timing of the placement of the definitive restoration, if it is to be carried out by another dental surgeon, is stressed.

Dental Restoration, Permanent↗

PubMed2003

Management of severe partial hypodontia: case report.

Hypodontia is characterized by partial or total congenital missing of one or more teeth, on one or both dentitions. Heredity is the main etiological factor and the principal clinical features are reduction on number, size and form of teeth, and late eruption. Removable partial prosthesis, fixed prosthesis, overdentures and adhesive prosthesis are alternative treatments; and the indication is type dependent. The aim of this study was to describe the clinical case of an eleven-year-old child with eight missing permanent teeth of idiopathic etiology. The patient had facial and skeletal symmetry, normal development and was not related to any syndrome. Clinical characteristics: permanent teeth with good periodontal conditions (16, 12, 11, 21, 22, 26, 36, 31, 42, 46), primary teeth (53, 63, 64, 73, 83); overbite and microdontia on teeth 12 and 22. The treatment plan was done initially by documenting of the case for teeth analysis (study casting models, periapicals and panoramic x-rays, and photographs), and followed by the exodontics of teeth 73 and 83. A removable appliance in autocured acrylic resin, using teeth in acrylic for maintenance of functional space and occlusion was planned and carried out. An anterior track for vertical dimension gain was used because of his accentuated overbite. The patient will be monitored until the end of the craniofacial growth, when it will be again evaluated and forwarded for the final oral rehabilitation. Hypodontia diagnosis and management should be performed as early as possible not to interfere with the craniofacial development of the child.

Age Factors↗

PubMed1975

[The ideal computer for ECG analysis (author's transl)].

An on-line minicomputer with a suitable structure turns out to be the ideal system for ECG interpretation. The motivations for this conclusion come both from the nature of the ECG analysis process and from the solution that the present state of the process and from the solution that the present state of the computer technology suggests for the controversy on large-scale computers versus minicomputers in the medical environment. In this paper both these aspects of the problem are briefly discussed and an ideal structure is proposed for a system based on a minicomputer. The main goals of this system are flexibility, adequate man-machine interfacing, low cost, high reliability and minimal maintenance, minimum installation space and site preparation.

Analog-Digital Conversion↗

PubMedDate not supplied

Method for the placement of palatal implants.

PURPOSE: Palatal implants have been used in the last 2 decades to eliminate headgear wear and to establish stationary anchorage. The aim of this investigation was to establish a method and easy protocol for palatal implant placement. MATERIALS AND METHODS: The study comprised 8 male and 15 female patients each having a 4.5 x 8-mm stepped screw titanium implant placed in the palatal region for orthodontic purposes. A surgical template containing metal drill housing was prepared. Angulation of the drill housing was controlled according to the radiologic tracing of the maxilla transferred to a plaster cast section in the paramedian plane. Implants were placed using a noninvasive technique (incision, flap, and suture elimination) and left transmucosally to facilitate the surgical procedure and reduce operations. The paramedian region was selected so as to avoid connective tissues of the palatine suture and because it was considered to be a suitable host site for implant placement. RESULTS: After 3 months of healing, all implants were osseointegrated and no implant was lost throughout the orthodontic treatment. DISCUSSION: Palatal implants can be used effectively for anchorage maintenance and space-gaining procedures. CONCLUSION: Usage of a 3-dimensional surgical template eliminated faulty implant placement, reduced chair time, and minimized trauma to the tissues while enhancing osseointegration.

Adult↗

PubMed2002

[Comparison of continuous spinal and combined spinal-epidural anesthesia in patients for uterectomy].

OBJECTIVE: To compare the anaesthetic effect and hemodynamic changes between the continuous spinal anaesthesia(CSA) and combined spinal-epidural anaesthesia (CSEA) in patients for uterectomy. METHODS: Sixty patients undergoing uterectomy were randomly divided into two groups: CSA group and CSEA group. Spinal anesthesia was performed at L2-3 interspace. An initial subarachnoid bolus of 0.5% hyperbaric bupivacaine 2 ml was injected in the CSA group; if analgesia did not reach T8, supplemental bupivacaine was injected by titrate incremental doses. In the CSEA group, epidural anesthesia was performed at T12-L1 with a catheter inserted into the epidural space for anesthesia maintenance, and then 0.5% hyperbaric bupivacaine 3 ml was injected to the subarachnoid at L2-3. The levels and times of sensory and motor block and hemodynamic changes were measured and analysed. RESULTS: The anesthetic dosage of the CSA group was smaller than that of the CSEA group (group P < 0.05). The times of sensory block to T8 or the maximal level and motor block were more rapid in the CSEA group than those of the CSA group (P < 0.05). Mean arterial pressure (MAP), which decreased significantly, was related with the baseline in the two groups; the time was 15 min and 25 min in the CSEA group and CSA group respectively (P < 0.05). There was no difference in the maximum decline of MAP in the two groups (P < 0.01). CONCLUSION: CSA is a safe technique of spinal anesthesia with small anesthetic dosages, more reliable and hemodynamically stable in patients for uterectomy.

Adult↗

PubMed1997

Guided bone regeneration: integration of a resorbable membrane and a bone graft material.

Guided bone regeneration relies primarily on four principles--exclusion of unwanted tissues and cells, space creation and maintenance, protection of the underlying blood clot, and wound stabilization. For successful bone regeneration to occur, large bony defects require an underlying grafting material and a cell-occlusive membrane. The learning objective of this article is to review the history and principles of guided bone regeneration and describe the characteristics of a slowly resorbing bilayer collagen membrane, well suited for bone regeneration procedures. An osteoconductive bone grafting material and its ability to support the overlying collagen membrane and serve as a matrix for the ingrowth of vascular and bone-forming cells are discussed.

Absorbable Implants↗

PubMed2003

Clinical results of a single central interbody fusion cage and transpedicle screws fixation for recurrent herniated lumbar disc and low-grade spondylolisthesis.

BACKGROUND: The posterior lumbar interbody fusion (PLIF) procedure allows restoration of the weight-bearing capacity to a more physiological ventral position and maintenance of disc space height. However, the procedure can be technically difficult and may cause complications. It has always been performed bilaterally with paired cages; a single central cage has not been commonly used. METHODS: Twenty-eight patients who met the interbody fusion criteria from March 1999 through November 2001 were included in the study. Surgery was performed from the posterior with a single central cage supplemented with transpedicle screws. The follow-up period ranged from 8 to 39 months with a mean of 14.4 months. Clinical outcomes were assessed. Dynamic radiography for fusion mass was interpreted by an independent radiologist. RESULTS: Overall, 92.86% of the patients were satisfied with their conditions after surgery. Radiography study showed the rate of bony fusion being 82.14%. Fibrous union was noted in five patients. No migration of the cage was observed. One patient experienced laceration of the dura without clinical sequelae. One patient had transient paresthesia and recovered within 2 weeks. One patient had transient bladder atony and recovered within 3 days. Overall, the complications were negligible and none of the patients sustained a motor deficit and permanent complication. CONCLUSIONS: The PLIF procedure using a single, central cage combined with bilateral pedicle screws fixation obtained satisfactory outcome within a short-term or long-term follow-up period. Since the implant-related complications have seldom been observed, it may be used as an alternative option for recurrent lumbar disc herniation or low grade spondylolisthesis with apparent degenerative disc disease.

Adult↗

PubMed1995

[The "Green Brigades" task-force. Description and practical information].

The General Rhône Council has set up a new task force, the "Green Brigades", which reflects awareness that the environment can serve as a means towards social and professional reinsertion. The field of activity is maintenance of open spaces on sites that are cleaned up on behalf of local authorities: removal of bulky matter, renovation of banks and riverbeds, clearing or making of footpaths, etc.

City Planning↗

PubMed1998

[Dysphagia caused by ossification of the anterior longitudinal ligament associated with diffuse idiopathic skeletal hyperostosis: report of 2 cases].

Two cases of ossification of the anterior longitudinal ligament (OALL) associated with diffuse idiopathic skeletal hyperostosis (DISH) presenting as dysphagia are reported. DISH has long been regarded as a radiological entity manifesting flowing ossification adjacent to the anterior and lateral borders of at least four contiguous vertebral bodies, maintenance of disc spaces, and a dearth of bony ankylosis and erosion of the apophyseal and sacroiliac joints. In the majority of cases, this entity shows an innocuous clinical course, but the dysphagia shown in our cases has also been documented in previous literature. Case 1 was a 63-year-old male developing progressive dysphagia and rhinolalia. Cervical X-rays and CT showed flowing OALL in the entire cervical spine. MRI demonstrated displacement of the trachea and esophagus by this mass. There was OALL in the thoracic and lumbar spine. Case 2 was a 62-year-old male who had undergone removal of ossification of the posterior longitudinal ligament (OPLL) from C2 to C5. He developed dysphagia and myelopathy. Cervical X-rays and CT demonstrated projection of OALL as well as posterior osteophytes at C5/6. MRI suggested that OALL had caused dysphagia, and osteophytes deteriorated myelopathy. Removal of OALL was carried out in these two cases. In case 2, removal of the osteophytes and herniated disc was carried out at the same time. Postoperative course was unremarkable with improvement of symptoms. Treatment of dysphagia due to OALL is considered to be conservative. However, surgical decompression should be considered in cases of marked projection of OALL obstructing the esophagus as shown in our cases.

Deglutition Disorders↗

PubMed1998

Intervertebral spacer as an adjunct to anterior lumbar fusion. Part II. Six-month implantation in baboons.

Failure of interbody fusions in the lumbar spine are common due to reliance on the graft for structural support during healing by creeping substitution. Support of the interspace with an implant should result in improved fusion success. The objective of this study was to evaluate the stability of the implant in vivo and its potential as an adjunct to promote interbody arthrodesis. Prototype 3, a porous coated intervertebral spacer with extension lugs made of Ti-6A1-4V, was implanted vertically between adjacent lumbar vertebrae anteriorly in four baboons undergoing anterior interbody fusion. The animals were allowed freedom of activity for 6 months before being killed. A transperitoneal approach was made exposing the L4-L5 or L5-L6 interspace. At time of killing, clinical evaluation of the implant-vertebral body construct showed stability to manual stresses applied in extension, flexion, and rotation. Serial radiographs taken during the 6 months of implantation showed no change in position or displacement of the implants. Axial and torsional cyclic loads were applied to each spine at 1 cycle/s for 20,000 cycles. Statistical analysis of the motion profiles for intact and implanted spines demonstrated no significant difference in axial or rotational displacements at the arthrodesis level or adjacent unoperated levels, L1 and L4. The in vivo 6-month study in baboons confirmed implant stability and maintenance of disc space height. Variable osseous healing was noted. Release of plasma spray beading may have resulted from improper application on the implant or micromotion within the construct. A better method to mechanically interlock the plungers is being studied. Clinical trials based on this work appear justified.

Aluminum↗

PubMed1995

Endoscopic technique for free flap harvesting.

We have described the current state of development of endoscopic techniques used for harvest of the latissimus dorsi and rectus abdominis muscles, two of the most versatile reconstructive tissue sources available to plastic surgeons. We also have described our clinical experience with harvest of jejunal segments. The potential for the use of these tissues without the conventional pattern of scarring is very exciting. The broader implications for harvesting other donor tissues such as the gracilis, internal oblique, and serratus anterior muscles, and the thoracodorsal and temporalis fascias are on the near horizon. More sophisticated instrumentation is necessary, however, to facilitate the endoscopic approach in the subcutaneous space. This will necessarily include the development of better mechanisms for the creation and maintenance of the optical space. Fortunately, advances in this important technology are occurring month by month as experience and interest heighten, and instrumentation is improved. With increased experience and instrumentation development, it is possible that minimally invasive tissue harvest will become the future standard.

Endoscopy↗

PubMed2002

Protein synthesis is required for the enhancement of long-term potentiation and long-term memory by spaced training.

Spaced training is generally more effective than massed training for learning and memory, but the molecular mechanisms underlying this trial spacing effect remain poorly characterized. One potential molecular basis for the trial spacing effect is the differential modulation, by distinct temporal patterns of neuronal activity, of protein synthesis-dependent processes that contribute to the expression of specific forms of synaptic plasticity in the mammalian brain. Long-term potentiation (LTP) is a type of synaptic modification that may be important for certain forms of memory storage in the mammalian brain. To explore the role of protein synthesis in the trial spacing effect, we assessed the protein synthesis dependence of hippocampal LTP induced by 100-Hz tetraburst stimulation delivered to mouse hippocampal slices in either a temporally massed (20-s interburst interval) or spaced (5-min interburst interval) fashion. To extend our studies to the behavioral level, we trained mice in fear conditioning using either a massed or spaced training protocol and examined the sensitivity of long-term memory to protein synthesis inhibition. Larger LTP was induced by spaced stimulation in hippocampal slices. This improvement of synaptic potentiation following temporally spaced synaptic stimulation in slices was attenuated by bath application of an inhibitor of protein synthesis. Further, the maintenance of LTP induced by spaced synaptic stimulation was more sensitive to disruption by anisomycin than the maintenance of LTP elicited following massed stimulation. Temporally spaced behavioral training improved long-term memory for contextual but not for cued fear conditioning, and this enhancement of memory for contextual fear was also protein synthesis dependent. Our data reveal that altering the temporal spacing of synaptic stimulation and behavioral training improved hippocampal LTP and enhanced contextual long-term memory. From a broad perspective, these results suggest that the recruitment of protein synthesis-dependent processes important for long-term memory and for long-lasting forms of LTP can be modulated by the temporal profiles of behavioral training and synaptic stimulation.

Animals↗

PubMed1998

Ultrastructural analysis of human epidermal CD44 reveals preferential distribution on plasma membrane domains facing the hyaluronan-rich matrix pouches.

We used immunogold staining and stereology to examine the ultrastructural localization and to estimate the relative content of CD44 in different strata and cell types of normal human epidermis. We found that CD44 existed almost exclusively on the plasma membranes; only rare labeling occurred on vesicular structures within the cytoplasm. Quantitation of the immunogold particles indicated that the labeling density of melanocytes corresponded to that of basal keratinocytes, and Langerhans cells displayed a labeling density of approximately 10% that of the surrounding spinous cells. Among keratinocyte strata, the highest labeling density occurred on spinous cells, suggesting upregulation of CD44 after detachment from the basement membrane. The plasma membrane distribution of CD44 was compartmentalized, with little signal on cell-cell and cell-substratum contact sites such as desmosomes, the plasma membrane domain facing the basement membrane, and the close apposition of terminally differentiating granular cells. In contrast, CD44 was abundant on plasma membrane domains facing an open intercellular space, rich in hyaluronan. This distribution is in line with a role of CD44 as a hyaluronan receptor, important in the maintenance of the intercellular space for nutritional and cell motility functions in stratified epithelia.

Biotinylation↗