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Biomedical subjects

M Sanders

Publications and source records attributed to M Sanders.

At least 73 records · Page 4Linked to original sources
PubMed1996

Radiosurgical management of meningiomas.

The management of residual, recurrent, or small skull base meningiomas is controversial. Stereotactic radiosurgery has emerged as an alternative treatment. We report our experience from September 1991 to August 1994 of treatment of 20 such patients [18 females -age 19-82 years, followed for 6-36 months (mean 15.5 months)] with the Leksell Gamma Knife. Nine patients were treated either with recurrent (2 patients-2 operations each) or residual tumor. Twelve patients had skull base, 3 optic nerve, 3 parasagittal, and 1 residual torcular tumor. Mean volume/diameter was 9.172 mm3/25 mm.

Adult↗
PubMed1996

Healthcare combinations. Part III: Cultural success through organizational involvement. Interview by Terry G. Williams.

Throughout the integration process, organizations must constantly envision new opportunities, create mechanisms for communication, set goals and build accountabilities at appropriate levels within the organization. Ideally, an integration process will identify and build cultural strengths wherever they are in the organization and minimize the negative impact of change. An integration process that taps the creative, productive potential throughout the organization will not only reap more benefit from the integration process itself, but also will successfully navigate the culture through the rough waters of change.

Decision Making, Organizational↗
PubMed1995

Distribution of polycyclic aromatic hydrocarbons in oyster (Crassostrea virginica) and surface sediment from two estuaries in South Carolina.

The concentration of polycyclic aromatic hydrocarbons (PAHs) was determined in oysters and sediments collected from two high salinity estuaries from the coast of South Carolina. The two estuaries were Murrells Inlet (urban), an estuary receiving urbanized drainage and run-off, and North Inlet (non-urban), receiving drainage from heavily forested terrain and minimal anthropogenic input. A minimum of thirty (30 stations were sampled in Murrells and North Inlets, respectively. A composite oyster sample (n = 30) was analyzed for each station. For sediment, a sample from the top 3-5 cm of the sediment surface from each station was analyzed. In oyster from Murrells Inlet, total PAHs concentrations within the 75 percentile were located in the northern portion of the estuary near marinas, adjacent to residential areas of high population density, near commercial enterprises or run-off from storm drains. Total PAHs within the 25 percentile were located near the mouth of the estuary. These results showed PAHs concentration gradient in the estuary that was highest in narrow creeks, where the urban shore interfaced with tidal creeks and lowest at the mouth of the estuary. In the case for sediment, a similar gradient was observed. In comparing the mean total PAHs of the two inlets, Murrells Inlet had significantly higher (p < 0.01) total PAHs concentrations than North Inlet for oyster and sediment, respectively. In comparing PAHs concentrations among the two matrices in Murrells Inlet, these data showed that the pattern of individual PAHs in oyster and in sediment were different. Oysters tended to accumulate the lower molecular weight and the more water-soluble PAHs compared to PAHs found in sediment. As expected, differences in octanol/water partition coefficient among individual PAHs and the greater persistence of the higher molecular weight PAHs contributed to the accumulation patterns in oyster and sediment.

Animals↗
PubMed1995

Sequence and domain organization of scruin, an actin-cross-linking protein in the acrosomal process of Limulus sperm.

The acrosomal process of Limulus sperm is an 80-microns long finger of membrane supported by a crystalline bundle of actin filaments. The filaments in this bundle are crosslinked by a 102-kD protein, scruin present in a 1:1 molar ratio with actin. Recent image reconstruction of scruin decorated actin filaments at 13-A resolution shows that scruin is organized into two equally sized domains bound to separate actin subunits in the same filament. We have cloned and sequenced the gene for scruin from a Limulus testes cDNA library. The deduced amino acid sequence of scruin reflects the domain organization of scruin: it consists of a tandem pair of homologous domains joined by a linker region. The domain organization of scruin is confirmed by limited proteolysis of the purified acrosomal process. Three different proteases cleave the native protein in a 5-kD Protease-sensitive region in the middle of the molecule to generate an NH2-terminal 47-kD and a COOH-terminal 56-kD protease-resistant domains. Although the protein sequence of scruin has no homology to any known actin-binding protein, it has similarities to several proteins, including four open reading frames of unknown function in poxviruses, as well as kelch, a Drosophila protein localized to actin-rich ring canals. All proteins that show homologies to scruin are characterized by the presence of an approximately 50-amino acid residue motif that is repeated between two and seven times. Crystallographic studies reveal this motif represents a four beta-stranded fold that is characteristic of the "superbarrel" structural fold found in the sialidase family of proteins. These results suggest that the two domains of scruin seen in EM reconstructions are superbarrel folds, and they present the possibility that other members of this family may also bind actin.

Acrosome↗
PubMed1995

High resolution magnetic resonance imaging of the anterior visual pathway in patients with optic neuropathies using fast spin echo and phased array local coils.

High resolution MRI of the anterior visual pathways was evaluated using frequency selective fat suppressed fast spin echo (FSE) sequences in conjunction with phased array local coils in patients with optic neuropathies. Fifteen normal controls and 57 patients were examined. Coronal T2 weighted fat suppressed FSE images were obtained in 11 minutes with an in plane resolution of 0.39 x 0.39 mm. The optic nerve and its sheath containing CSF were clearly differentiated. Central retinal vessels were often visible. In demyelinating optic neuritis and in anterior ischaemic optic neuropathy high signal within the nerve was readily delineated. Meningiomas and gliomas involving the optic nerve were precisely visualised both in the orbit and intracranially. Extrinsic compression of the optic nerves was readily visualised in carotid artery ectasia and dysthyroid eye disease. Enlarged subarachnoid spaces around the optic nerves were demonstrated in benign intracranial hypertension. High resolution MRI of the anterior visual pathway represents an advance in the diagnosis and management of patients presenting with optic neuropathy.

Adult↗
PubMed1995

Safety of unilateral and bilateral percutaneous cervical cordotomy in 80 terminally ill cancer patients.

PURPOSE AND METHODS: The safety of percutaneous cervical cordotomy (PCC) and bilateral percutaneous cervical cordotomy (BPCC) was studied in 62 and 18 patients, respectively, with intractable malignant pain. Cordotomy was indicated for pain that did not respond to any other therapy. RESULTS: After PCC, 54 patients showed satisfactory, six partial, and two no pain relief. Concerning major permanent complications, urinary retention, hemiparesis, and mirror-image pain occurred in four (6.5%), five (8.1%), and four (6.5%) patients, respectively. After BPCC, nine patients showed satisfactory, six partial, and three no pain relief. The major permanent complications were the same as after PCC, and occurred in two (11.1%), two (11.1%), and one (5.6%) patient, respectively. Sleep-induced apnea was not observed in any patient. CONCLUSION: In the treatment of intractable malignant pain, localized unilaterally, if other symptomatic management fails, PCC is a recommendable procedure, particularly when pain due to movement dominates. However, due to the high incidence of complications combined with the high failure rate, BPCC is not recommended.

Adult↗
PubMed1995

beta-Scruin, a homologue of the actin crosslinking protein scruin, is localized to the acrosomal vesicle of Limulus sperm.

Scruin (alpha-scruin) is an actin bundling protein found in the acrosomal process of Limulus polyhemus sperm. We have cloned and sequenced a second scruin isoform from Limulus, beta-scruin, that is 67% identical to alpha-scruin. Northern and Southern analyses confirm that beta-scruin and alpha-scruin are encoded by distinct genes. The sequence of beta-scruin, like alpha-scruin, is organized into N- and C-terminal superbarrel domains that are characterized by a six-fold repeat of a 50 residue motif. Western analysis using rabbit polyclonal antisera specific for alpha- and beta-scruin indicate that beta-scruin, like alpha-scruin, is found in Limulus sperm but not blood or muscle. Both immunofluorescence microscopy and immunogold-EM localize beta-scruin within the acrosomal vesicle at the anterior of sperm but not in the acrosomal process. The function of beta-scruin in this membrane-bounded compartment that is devoid of actin is unknown. However, the location of beta-scruin together with the fact that it contains two putative beta-superbarrel structural folds, which are known to be catalytic domains in a number of proteins, suggests it may have a possible enzymatic role.

Acrosome↗
PubMed1994

Molecular and cellular concepts in atherosclerosis.

Atherosclerosis is a complex disease of uncertain cause. Its pathobiology is believed to represent an abnormal expression of the processes of vascular healing. Etiologic models derive from a 'response to injury' paradigm and can be divided into three separate disease stages: endothelial dysfunction, smooth muscle proliferation and architectural disruption. The initiating event of endothelial dysfunction is unknown, but is believed to be related to low-density lipoproteins and/or their oxidized derivatives. Endothelial injury is signalled to the smooth muscle cells of the media by three routes: direct cell-cell interaction, secretion of soluble growth factors and monocyte-derived cytokines. Monocytes are recruited by the endothelium and invade the subintimal space by a complex interaction of a variety of adhesion proteins and receptors on both cell types. Smooth muscle cell proliferation is initiated by a change in phenotype expression from 'contractile' to 'synthetic' resulting from the binding of fibronectin to specific integrin receptors. Three functionally distinct activities may represent separate subtypes of the 'synthetic phenotype': migration from the media to the intima, increased proliferation and inappropriate extracellular matrix synthesis. The loss of normal regulatory control and anchorage independence of proliferation suggest a relationship to oncogenic transformation. Both migration and proliferation result from the binding of platelet-derived growth factor-like factors to smooth muscle cell receptors, which initiates a cascade of intracellular molecular events leading either to cytoskeletal locomotory restructuring or cell cycle activation. Both pathways also appear to be coregulated by integrin receptors and both depend upon phosphorylation of cell membrane, cytosolic and nuclear regulatory proteins. Clinical expression of atherosclerosis may follow sudden loss of architectural integrity of the intimal plaque by three different mechanisms: plaque fissuring, intraluminal plaque rupture or intramural hemorrhage related to abnormal vessel wall stress and/or biochemistry.

Animals↗
PubMed1994

Portable recording in the assessment of obstructive sleep apnea. ASDA standards of practice.

The objective assessment of patients with a presumptive diagnosis of obstructive sleep apnea (OSA) has primarily used attended polysomnographic study. Recent technologic advances and issues of availability, convenience and cost have led to a rapid increase in the use of portable recording devices. However, limited scientific information has been published regarding the evaluation of the efficacy, accuracy, validity, utility, cost effectiveness and limitations of this portable equipment. Attaining a clear assessment of the role of portable devices is complicated by the multiplicity of recording systems and the variability of clinical settings in which they have been analyzed. This paper reviews the current knowledge base regarding portable recording in the assessment of OSA, including technical considerations, validation studies, potential advantages and disadvantages, issues of safety, current clinical usage and areas most in need of further study.

Ambulatory Care↗
PubMed1993

Vasopressin receptor-mediated endocytosis in cells transfected with V1-type vasopressin receptors.

We examined the process of receptor-mediated endocytosis in A-9 lung fibroblast and chinese hamster ovary (CHO) cells transfected with the recently cloned vasopressin V1a receptor (51). We used a fluorescent labeled vasopressin analog (rhodamine-mercaptopropionic acid lysine vasopressin) and radiolabeled vasopressin to examine this process in the two transfected cell lines. Both A-9 and CHO cells internalize vasopressin in a manner consistent with receptor-mediated endocytosis. A-9 cells internalize vasopressin more rapidly than CHO cells. The process is inhibited by vasopressin and by specific vasopressin V1 receptor antagonists but not by specific V2 receptor antagonists. Hypertonic sucrose inhibits endocytosis in both cell types suggesting a role of clathrin coated pits in the endocytosis of receptor in these cells. These cells are excellent models in which to examine the effect of receptor mutations on vasopressin receptor-mediated endocytosis.

Animals↗
PubMed1993

Beam profile analysis using GafChromic films.

GafChromic film dosimetry techniques were used to evaluate the beam profiles for each collimator of the Leksell Gamma Knife at the University of Kentucky Medical Center. At the conclusion of acceptance testing, representatives from Leksell exposed conventional films for beam profile processing and analysis in Sweden. At the same time, an inhouse technique using GafChromic films was utilized in the analysis of the beam profiles. GafChromic films were irradiated to 100 Gray to provide data in each of the three planes for each collimator size. The films were analyzed using a scanning helium-neon laser densitometer with a small aperture of 5-10 microns. The digitized density profiles were curve-fitted using a PC plotting algorithm. The curve-fitted density profiles were converted to relative dose using a standard calibration curve determined with a conventional cobalt-60 teletherapy beam. The results are in excellent agreement with the conventional film analysis reported by Leksell. The GafChromic method has proven to be an accurate and rapid method of analysis and could be easily incorporated into a quality assurance program.

Calibration↗
PubMed1993

A tissue equivalent phantom for stereotactic radiosurgery localization and dose verification.

A tissue equivalent head phantom was utilized in the stereotactic localization and dose verification of radiosurgery procedures with the Leksell Gamma Knife Unit at the University of Kentucky Medical Center. A radiation dose-dependent color-doped gel target was positioned within the head phantom and stereotactically localized using either angiography, CT, or MR techniques. Utilizing standard Gamma Knife treatment procedures, the head phantom was irradiated, which resulted in a color change of the gel tumor at the position of the treatment isocenter and thereby confirmed the localization procedure. Additionally, a radiation dosimeter (thermoluminescent dosimetry--TLD) was positioned within the head phantom and localized using an angiography frame and a standard radiation therapy simulator. The phantom skull measurements and the dosimeter coordinates were entered into the Leksell Gamma Knife dose planning computer (KULA) and an irradiation time for 40 Gy using the 18-mm collimator was determined. The TLD dose evaluations were relatively determined using a cobalt-60 calibration curve. The experimental dose verification results agreed well (+/- 4%) with computer dose estimates.

Algorithms↗
PubMed1993

American Orthopaedic Foot and Ankle Society women's shoe survey.

Shoes have been implicated as being responsible for the majority of foot deformities and problems that physicians encounter in women. A total of 356 women were studied in this investigation to evaluate trends in women's shoe wear and their effect on the development of foot deformities and pain. The majority of women in this study wore shoes that were too small for their feet, had foot pain and deformity, and had increased shoe size since the age of 20. Few women had their feet measured in over 5 years. The women without foot pain or deformities also wore shoes that were smaller than their feet but to a lesser degree.

Adult↗