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Biomedical subjects

S J Nelson

Publications and source records attributed to S J Nelson.

At least 55 records · Page 3Linked to original sources
PubMed1998

Dynamic stereotactic radiosurgery: the Charleston program: a report on the first 150 patients.

We have been pleased with our initial experience in an evolving program. As newer surgical and radiotherapy techniques have become available, the role of radiosurgery has been and will continue to be modified. As more commercially available systems have been marketed, the availability will become more widespread. A battery of residents in neurosurgery and radiation oncology trained in these technologies will provide leadership and future directions of this therapy.

Adolescent↗
PubMed1998

A randomized controlled trial and economic evaluation of counselling in primary care.

BACKGROUND: Counselling in primary care settings remains largely unevaluated. Such evaluation has been strongly recommended. AIM: To determine the relative effectiveness and cost-effectiveness of generic counselling and usual general practitioner (GP) care for patients with minor mental health problems. METHOD: A randomized controlled trial and health economic evaluation were carried out in nine general practices. Access to generic counselling (brief counselling, generally involving up to six 50-minute sessions) was compared with usual GP care. A total of 162 patients aged 16 years and over with diverse mental health problems (excluding phobic conditions and psychoses) were randomized. The Hospital Anxiety and Depression (HAD) scale, COOP/WONCA (World Organization of Family Doctors) functional health assessment charts, and the delighted-terrible faces scale were used to assess outcome four months after randomization. RESULTS: The two groups were similar at baseline. There were significant improvements in both groups between randomization and follow-up for most outcome measures, but no significant differences between the study arms. The 95% confidence limits were narrow and excluded clinically significant effects. Under various assumptions concerning the cost of secondary care referrals and of counselling time, no clear cost advantage was associated with either intervention. CONCLUSIONS: This pragmatic trial demonstrates no difference in functional or mental health outcome at four months between subjects offered access to counselling and those given usual care by their GP. There is no clear difference in the cost-effectiveness of the two interventions. Purchasers should take account of these findings in allocating resources within primary care.

Adult↗
PubMed1998

Beyond synonymy: exploiting the UMLS semantics in mapping vocabularies.

The Unified Medical Language System (UMLS) contains semantic information about terms from various sources, each concept can be understood and located by its relationships to other concepts: this is a result of the organizing principle of semantic locality. We describe a method in which the semantic relationships between concepts are used to map concepts from different vocabularies in the UMLS. Applied to mapping concepts to MeSH, this method is able to map 50 to 65% of the non-MeSH concepts to MeSH. A manual review of the mapping shows a relevance rate of 61%. Causes of failure include a lack of consistently represented relationships in the UMLS, and some inconsistencies in the categorization of the concepts. The limits of this method are discussed, as well as possible adaptations for other uses.

Algorithms↗
PubMed1997

High spatial resolution and speed in MRSI.

The in vivo applications of magnetic resonance spectroscopic imaging (MRSI) have expanded significantly over the past 10 years and have reached the point where clinical trials are underway for a number of different diseases. One of the limiting factors in the widespread use of this technology has been the lack of widely available tools for obtaining data which are localized to sufficiently small tissue volumes to make an impact upon diagnosis and treatment planning. This is especially difficult within the timeframe of a clinical MR examination, which requires that both anatomic and metabolic data are acquired and processed. Recent advances in the hardware and software associated with clinical scanners have provided the potential for improvements in the spatial and time resolution of imaging and spectral data. The two areas which hold the most promise in terms of MRSI data are the use of phased array coils and the implementation of echo planar k-space sampling techniques. These could have immediate impact for 1H MRSI and may prove valuable for future applications of 31P MRSI.

Brain Neoplasms↗
PubMed1997

Improved water and lipid suppression for 3D PRESS CSI using RF band selective inversion with gradient dephasing (BASING).

A T1 insensitive solvent suppression technique-band selective inversion with gradient dephasing (BASING)-was developed to suppress water and lipids for 1H magnetic resonance spectroscopy (MRS). BASING, which consists of a frequency selective RF inversion pulse surrounded by spoiler gradient pulses of opposite signs, was used to dephase stopband resonances and minimally impact passband metabolites. Passband phase linearity was achieved with a dual BASING scheme. Using the Shinnar-Le Roux algorithm, a highpass filter was designed to suppress water and rephase the lactate methyl doublet independently of TE, and water/lipid bandstop filters were designed for the brain and prostate. Phantom and in vivo experimental 3D PRESS CSI data were acquired at 1.5 T to compare BASING with CHESS and STIR suppression. With BASING, the measured suppression factor was over 100 times higher than with CHESS or STIR causing baseline distortions to be removed. It was shown that BASING can be incorporated into a variety of sequences to offer improved suppression in the presence of B1 and T1 inhomogeneites.

Brain Chemistry↗
PubMed1997

Antibiotic prophylaxis for pit viper envenomation: prospective, controlled trial.

The efficacy of prophylactic antibiotics for preventing infectious complications at the site of pit viper envenomation has not been well studied. We undertook a prospective, controlled trial of antibiotic treatment versus no antibiotic treatment among 114 victims of crotalid envenomation in Ecuador's Amazon rain forest. A group of 59 patients received intravenous gentamicin and chloramphenicol, and 55 patients did not. All other aspects of care were identical. There were no statistically significant differences between antibiotic-treated and untreated patients with regard to demographics, delay in treatment, clinical and laboratory evidence of severity of envenomation, or use of antivenin. Nine abscesses occurred, six in the antibiotic-treated group and three in the untreated group. The results of this study did not show any statistically significant differences in outcome in terms of the number of abscesses that occurred between antibiotic-treated and untreated patients. Based on this lack of differences, routine use of prophylactic antibiotics for prevention of infectious complications of crotalid envenomation cannot be recommended.

Abscess↗
PubMed1997

Prevalence of modalities of headaches and bruxism among patients with craniomandibular disorder.

This study compared the presence of headache and bruxing behavior among 133 craniomandibular disorder patients (CMD) referred to the The Center For the Study Of Craniomandibular Disorders and to the presence of headache and bruxing behavior occurring in 133 controls seeking routine dental care. Both patients and controls were consecutive referrals to the clinic occurring over a three year period. The mean age of the CMD group was 38 years (range 28-42), and the mean age of the controls was 37 years (range 25-44). The information gathered included questionnaire and clinical examination. Different types of headaches, signs and symptoms of CMD, and bruxing behavior were assessed both in the CMD group and in the corresponding control group. Results of this study showed that bruxing behavior and headache pain were significantly more prevalent in the CMD group (57%, 76%) than in the corresponding control group (37%, 49%). Of the three types of headache observed, tension and combination headaches were more prevalent in the CMD group (n = 48 = 36% and n = 37 = 28%). Migraine headache was more prevalent in the CMD group (n = 16 = 12%) than in the control group (n = 3 = 2%). It was concluded that headache and bruxing behavior predominated in CMD patients. This data reinforces the need to assess headache pain and signs and symptoms of bruxing behavior in CMD patients, particularly in those suffering chronic facial pain and headache.

Adult↗
PubMed1997

Effect of ciprofloxacin on the accumulation of interleukin-6, interleukin-8, and nitrite from a human endothelial cell model of sepsis.

OBJECTIVE: To determine the effect of the quinolone antibiotic ciprofloxacin, on interleukin-6, interleukin-8, and nitrite production by human endothelial cells. DESIGN: Controlled cell culture experiments examining the immunomodulatory effects of an antibiotic. SETTING: University research laboratory attached to a large teaching hospital. SUBJECTS: A human endothelial cell line. MEASUREMENTS AND MAIN RESULTS: Cells were incubated with tumor necrosis factor-alpha and interleukin-1beta in the presence of a range of ciprofloxacin concentrations. Interleukin-6, interleukin-8, and nitrite concentrations were measured in culture supernatants after 24 hrs using enzyme immunoassay. Ciprofloxacin decreased interleukin-6 accumulation (p = .001). Interleukin-8 was decreased at lower ciprofloxacin concentrations (p = .017) but was increased at 100 microg/mL (p = .0039). Ciprofloxacin had no effect on nitrite accumulation (p = .38). CONCLUSIONS: Ciprofloxacin differentially modulates interleukin-6 and interleukin-8 expression. The response to infection is coordinated by a cascade of cytokines and other mediators. The widespread use of ciprofloxacin in patients with severe infections is likely to result in alterations in local concentrations of cytokines. Selective control of cytokine concentrations by antibacterial agents will clearly have important therapeutic implications and may be a future research consideration in antibiotic drug design.

Anti-Infective Agents↗
PubMed1997

Serial proton magnetic resonance spectroscopy imaging of glioblastoma multiforme after brachytherapy.

The utility of three-dimensional (3-D) proton magnetic resonance spectroscopy (1H-MRS) imaging for detecting metabolic changes after brain tumor therapy was assessed in a serial study of 58 total examinations of 12 patients with glioblastoma multiforme (GBM) who received brachytherapy. Individual proton spectra from the 3-D array of spectra encompassing the lesion showed dramatic differences in spectral patterns indicative of radiation necrosis, recurrent or residual tumor, or normal brain. The 1H-MRS imaging data demonstrated significant differences between suspected residual or recurrent tumor and contrast-enhancing radiation-induced necrosis. Regions of abnormally high choline (Cho) levels, consistent with viable tumor, were detected beyond the regions of contrast enhancement for all 12 gliomas. Changes in the serial 1H-MRS imaging data were observed, reflecting an altered metabolism following treatment. These changes included the significant reduction in Cho levels after therapy, indicating the transformation of tumor to necrotic tissue. For patients who demonstrated subsequent clinical progression, an increase in Cho levels was observed in regions that previously appeared either normal or necrotic. Several patients showed regional variations in response to brachytherapy as evaluated by 1H-MRS imaging. This study demonstrates the potential of noninvasive 3-D 1H-MRS imaging to discriminate between the formation of contrast-enhancing radiation necrosis and residual or recurrent tumor following brachytherapy. This modality may also allow better definition of tumor extent prior to brachytherapy by detecting the presence of abnormnal metabolite levels in nonenhancing regions of solid tumor.

Aspartic Acid↗
PubMed1996

Intracranial tumors in children: small single-voxel proton MR spectroscopy using short- and long-echo sequences.

We report preliminary experience using single-voxel, proton MR spectroscopy (MRS) employing small voxels of interest, in combination with short and long echo-time protocols, for the assessment of primary intracranial tumors in children. We examined 23 children with primary intracranial tumors detected by MRI, and 32 controls with similar ages, using MRS on a 1.5 T system. Localized single-voxel (3.7 +/- 1.3 cc) proton spectra were obtained with short-echo (2,000/18), stimulated-echo (STEAM) and long-echo (2,000/270) spin-echo (PRESS) protocols. All spectra were evaluated qualitatively; 10 tumor and 19 control spectra were processed for peak area quantification. Small voxels of interest were able to account for tissue heterogeneity. Combined acquisition of short- and long-echo spectra increased the number of detectable metabolites. The solid portion of all tumors exhibited reduced N-acetyl-aspartate (NAA), strong contribution from cholines (Cho) and inositols or glycine, minimal presence of total creatine (tCr), enhanced broad mobile lipid resonances and accumulated lactate. Calculated selected metabolite ratios of Cho/tCr and Cho/NAA were substantially increased from control values. The cystic portions of the masses showed only lipid and lactate peaks.

Adolescent↗
PubMed1996

Detection of locally recurrent prostate cancer after cryosurgery: evaluation by transrectal ultrasound, magnetic resonance imaging, and three-dimensional proton magnetic resonance spectroscopy.

OBJECTIVES: To assess and compare the clinical usefulness of transrectal ultrasound (TRUS), magnetic resonance imaging (MRI), and three-dimensional proton magnetic resonance spectroscopic imaging (3-D MRSI) in detecting local recurrence of carcinoma of the prostate (CaP) in patients with detectable prostate-specific antigen (PSA) levels after cryosurgery. METHODS: In a prospective study, 25 patients who had undergone cryosurgery as primary treatment for CaP underwent endorectal MRI and 3-D MRSI, followed by TRUS-guided prostate biopsy. At the time of study, 20 patients had detectable PSA; the remaining 5 patients served as controls. All patients had random sextant and guided prostate biopsy for correlation with imaging and MR spectroscopic findings. RESULTS: In patients with detectable PSA, MRSI identified, location-for-location, all foci of CaP and benign prostatic tissue that were detected by prostate biopsy. MRSI identified more sites with CaP than did prostate biopsy, indicating a larger volume of cancer. In 2 patients with detectable PSA and negative prostate biopsy, MRSI identified 11 voxels with viable prostatic tissue. In patients with undetectable PSA, both MRSI and prostate biopsy showed necrosis. Ultrasound and MRI were very poor tools for identifying recurrent cancer and differentiating between viable and necrotic prostate tissue. CONCLUSIONS: 3-D MRSI is superior to TRUS and MRI in differentiating among CaP, BPH, and necrosis when local recurrence after cryosurgery is suspected. By providing chemical mapping of the prostate in contiguous voxels, the addition of spectroscopy to endorectal MRI increases the sensitivity for detection of local recurrence.

Aged↗
PubMed1996

Geometric analysis of occlusal plane orientation using simulated ear-rod facebow transfer.

PURPOSE: Ear-rod facebow techniques may position casts high or low between the upper and lower members on the articulator when using orbitale or nasion as anterior reference positions. This study assessed the effect of changing the anterior reference position on simulated mountings utilizing simulated ear-rod facebow. MATERIALS AND METHODS: Tracings from latoral cephalographs made on seven subjects were superimposed with an outline model of a semiadjustable articulator. Three simulated mountings were performed for each subject in which the plane of occlusion was positioned (1) high, (2) midway, and (3) approaching the lower member (low). Maxillary and mandibular occlusal planes representing intercuspal position were determined from the cephalographs and positioned on the articulator model in a simulated centric relation position for each mounting. Condylar guidance was determined from a simulated protrusive position. RESULTS: Analysis of the three mounting positions demonstrated no change in intercuspal position within subjects; however, angles formed between upper member and condylar guidance were 14.9% smaller for the mid-distance mounting, 42.9% smaller for the high mounting, and 13.4% higher for the low mounting positions when compared with a standard Frankfort horizontal plane reference. CONCLUSIONS: The cephalographs showed extreme variability in the position of the ear piece to bony structures of the skull, but this deviation appeared to be compensated by a change in the horizontal condylar guidance relative to mounting. Results also suggest that casts may be mounted in a convenient mid-position for routine articulation.

Cephalometry↗
PubMed1996

Three-dimensional H-1 MR spectroscopic imaging of the in situ human prostate with high (0.24-0.7-cm3) spatial resolution.

PURPOSE: To evaluate if three-dimensional hydrogen-1 magnetic resonance spectroscopic imaging (3D MRSI) when combined with a clinical MR imaging examination could discriminate prostatic adenocarcinoma from normal prostatic zonal anatomy and benign prostatic hyperplasia (BPH) on the basis of observable metabolite levels. MATERIALS AND METHODS: Combined phased-array, endorectal MR imaging and 3D MRSI was performed in nine young healthy volunteers, five patients with BPH, and 85 patients with prostate cancer and BPH. Volume MR imaging and 3D MRSI data were analytically corrected for the reception profile of the endorectal and pelvic phased-array coils, aligned with the MR imaging data, and compared with postoperative pathologic histology findings. RESULTS: Statistically significant variations in metabolite levels with prostatic zonal anatomy, age, and pathologic condition were detected with a 3D MRSI examination added to a clinical MR imaging examination. Significantly higher choline levels and significantly lower citrate levels were observed in regions of cancer compared with BPH and normal peripheral zone tissues. The ratio (choline + creatine/citrate) in regions of cancer (2.1 +/- 1.3 [standard deviation]) had no overlap with normal peripheral zone values and minimal overlap with BPH values (0.61 +/- 0.21). An estimate of the spatial extent of prostate cancer was determined by generating metabolite images in which this metabolite ratio significantly exceeded normal peripheral zone values in multiple contiguous sections. CONCLUSION: These results suggest that a 3D MRSI examination added to a clinical MR imaging examination may help define the presence and spatial extent of prostate cancer.

Adenocarcinoma↗
PubMed1996

Prostate cancer: metabolic response to cryosurgery as detected with 3D H-1 MR spectroscopic imaging.

PURPOSE: To determine, in patients with prostate cancer treated with cryosurgery, whether levels of choline and citrate measured at magnetic resonance (MR) spectroscopy can help discriminate regions of residual tumor from other prostatic tissues and necrosis. MATERIALS AND METHODS: Combined MR imaging and three-dimensional proton spectroscopic imaging were performed in 25 patients (mean age, 69 years) with prostate cancer who underwent cryosurgery. Volume imaging and spectroscopic data were analytically corrected for the reception profile of the endorectal and pelvic phased-array coils. Spectral data were aligned with the MR imaging data and compared with serum prostate-specific antigen levels and biopsy results. RESULTS: Histologically confirmed necrotic tissue (432 voxels) did not demonstrate any observable choline or citrate. The (choline + creatine)/ citrate values in regions of histologically confirmed benign prostatic hyperplasia (0.61 +/- 0.21 [standard deviation], 52 voxels) and cancer (2.4 +/- 1.0, 65 voxels) after cryosurgery were not statistically significantly different from those before therapy but were statistically significantly different from the ratio in necrotic tissue and from each other. The (choline + creatine)/citrate images threshold and overlaid in color on T2-weighted images yielded an estimate of the spatial extent of prostate cancer and benign prostatic hyperplasia. CONCLUSION: Volume MR imaging with MR spectroscopic imaging provided a noninvasive assessment of the presence and location of residual cancer after unsuccessful therapy and helped identify successful cryosurgery in patients who still had an elevated prostate-specific antigen level.

Aged↗
PubMed1996

MEME-II supports the cooperative management of terminology.

Health care enterprises need enterprise-wide terminologies to compare, reuse and repurpose health care descriptions. But once they are created, these terminologies need to be maintained and enhanced to sustain their utility and that of the descriptions encoded with them. MEME II (Metathesaurus Enhancement and Maintenance Environment, Version II) supports the required activities and enables enterprises to leverage their investment in terminology and descriptions by permitting remote-extra-enterprise-enhancements to terminology to be incorporated locally, and local-intra-enterprise-enhancements to be shared remotely. MEME II represents all changes to terminologies as data, or "actions," that can be interpreted by an "action engine." These actions, or messages, represent semantic "units of work" that can be interpreted by other copies of MEME II. The exchange of update messages increases the likelihood that the comparability of terminology-based health care descriptions can be sustained.

Information Systems↗
PubMed1996

Toward reusable software components at the point of care.

An architecture built from five software components -a Router, Parser, Matcher, Mapper, and Server -fulfills key requirements common to several point-of-care information and knowledge processing tasks. The requirements include problem-list creation, exploiting the contents of the Electronic Medical Record for the patient at hand, knowledge access, and support for semantic visualization and software agents. The components use the National Library of Medicine Unified Medical Language System to create and exploit lexical closure-a state in which terms, text and reference models are represented explicitly and consistently. Preliminary versions of the components are in use in an oncology knowledge server.

Computer Systems↗
PubMed1996

A poor precedent.

The single greatest impediment to the successful leveraging of computer-based patient records (CPRs) is the difficulty of creating and maintaining comparable patient descriptions. Specifically, it will be hard to justify the investment required to deploy CPRs widely if the patient descriptions they store are not comparable across successive releases of controlled health-care vocabularies. Thus, it is necessary to solve the controlled health-care vocabulary update problem for CPRs before the comparability of patient descriptions can be sustained. What may seem to be a narrow technical problem of interest only to maintainers of health-care enterprise systems is, instead, a central problem of medical informatics. Cimino's "Formal descriptions and adaptive mechanisms for changes in controlled medical vocabularies" describes a classification of the changes appearing in the 1994 Edition of the International Classification of Diseases (ICD-9-CM). His paper describes the conversion of differences detected between the 1993 and 1994 releases of ICD-9-CM and a conversion of the elements of the classification into the required formal changes to the Medical Entities Dictionary (MED), part of the CPR in use at Columbia Presbyterian Medical Center. Because the process of detecting differences begins with an empirical analysis of the ASCII representations of the 1993 and 1994 releases of ICD-9-CM, it is impossible for a computer program to infer the intent of the changes that caused the differences; instead, a content expert must infer the intent and then update the MED accordingly. A typical task is to infer whether a change in naming also reflects a change in the meaning named. While Cimino's methods and their execution are exemplary in every respect, they nevertheless constitute a kind of "reverse engineering"-an ad hoc attempt to infer intent from details. Reverse engineering of changes to controlled medical vocabularies is a poor precedent. Such methods should be viewed as necessary short-term expedients only, and all parties concerned should work toward an incremental plan by which the intent of changes to controlled health-care vocabularies can be made both explicit and machine processible. Only then can the comparability of patient descriptions be sustained.

Disease↗