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Biomedical subjects

S W Smith

Publications and source records attributed to S W Smith.

At least 19 recordsLinked to original sources
PubMed2004

Real-time 3D transesophageal echocardiography.

Transesophageal echocardiography (TEE) is an essential diagnostic tool in patients with poor transthoracic echocardiographic windows or when detailed imaging of structures distant from the chest wall is necessary. A real-time 3D TEE probe has been fabricated in our laboratory in order to increase the amount of information available during a transesophageal procedure. The 1 cm diameter esophageal probe utilizes a 2-dimensional, 5 MHz array at its tip with a 6.3 mm diameter aperture, including 504 active channels. The array has a periodic vernier geometry with an element pitch of 0.18 mm, built onto a multilayer flexible (MLF) interconnect circuit. In order to accommodate 504 channels within the device, a 1 m long Gore MicroFlat cable was utilized for wiring the MLF to the corresponding system connectors. Pulse-echo tests in a water tank have yielded a -6 dB bandwidth of 25.3%. Fully connected to the system through 3 m of cable, the probe shows an average 50 omega insertion loss of-85 dB with a standard deviation of 4 dB, as determined through pitch-catch measurements for a sampling of 10 elements. Using the completed 3D TEE probe with the Volumetrics Medical Imaging 3D scanner, real-time volumetric images of in vivo canine cardiac anatomy have been acquired, displaying atrial views, mitral valve function and interventional catheter guidance.

Animals↗
PubMed2003

Electrostatic micromachine scanning mirror for optical coherence tomography.

Compact electrostatic micromirror structures for use in the scanning arm of an optical coherence tomography (OCT) system are described. These devices consist of millimeter-scale mirrors resting upon micrometer-scale polyimide hinges that are tilted by a linear micromachine actuator, the integrated force array (IFA). The IFA is a network of deformable capacitor cells that electrostatically contract with an applied voltage. The support structures, hinges, and actuators are fabricated by photolithography from polyimide-upon-silicon wafers. These devices were inserted into the scanning arm of an experimental OCT imaging system to produce in vitro and in vivo images at frame rates of 4 to 8 Hz.

Electricity↗
PubMed2003

Behavioral correction of Parkinsonian rats following the transplantation of immortalized fibroblasts genetically modified with TH and GCH genes.

Eukaryotic plasmid vectors encoding the tyrosine hydroxylase (TH) gene and GTP cyclohydrolase-1 (GCH) gene were constructed and introduced into immortalized fibroblasts obtained from SV40 large antigen (LT(AG)) transformed rat primary fibroblasts. TH and GCH positive clones were selected and identified by immunohistochemistry and RT-PCR, respectively. Hemi-parkinsonian rats created using 6-hydroxydopamine (6-OHDA) were used to assess the therapeutic effect created by the co-implantation of immortalized fibroblasts genetically modified by TH or GCH genes. Animal behavior was significantly improved two weeks following implantation and behavioral correction was maintained for over 14 weeks. Behavioral improvement was paralleled by exogenous TH gene expression, identified by TH immunohistochemistry and RT-PCR analyses. The transplanted cells survived for at least 38 weeks as demonstrated by fibronectin immunohistochemical staining. Tumor formation or host reaction was not seen, although TH expression was negative for 20 weeks after the implantation. This work demonstrates that the co-transplantation of immortalized fibroblasts genetically modified by TH and GCH genes may be developed as a valuable approach to the treatment of Parkinson's disease.

Animals↗
PubMed2003

Real-time cylindrical curvilinear 3-D ultrasound imaging.

In patients who are obese or exhibit signs of pulmonary disease, standard transthoracic scanning may yield poor quality cardiac images. For these conditions, two-dimensional transesophageal echocardiography (TEE) is established as an essential diagnostic tool. Current techniques in transesophageal scanning, though, are limited by incomplete visualization of cardiac structures in close proximity to the transducer. Thus, we propose a 2D curvilinear array for 3D transesophageal echocardiography in order to widen the field of view and increase visualization close to the transducer face. In this project, a 440 channel 5 MHz two-dimensional array with a 12.6 mm aperture diameter on a flexible interconnect circuit has been molded to a 4 mm radius of curvature. A 75% element yield was achieved during fabrication and an average -6dB bandwidth of 30% was observed in pulse-echo tests. Using this transducer in conjunction with modifications to the beam former delay software and scan converter display software of the our 3D scanner, we obtained cylindrical real-time curvilinear volumetric scans of tissue phantoms, including a field of view of greater than 120 degrees in the curved, azimuth direction and 65 degrees phased array sector scans in the elevation direction. These images were achieved using a stepped subaperture across the cylindrical curvilinear direction of the transducer face and phased array sector scanning in the noncurved plane. In addition, real-time volume rendered images of a tissue mimicking phantom with holes ranging from 1 cm to less than 4 mm have been obtained. 3D color flow Doppler results have also been acquired. This configuration can theoretically achieve volumes displaying 180 degrees by 120 degrees. The transducer is also capable of obtaining images through a curvilinear stepped subaperture in azimuth in conjunction with a rectilinear stepped subaperture in elevation, further increasing the field of view close to the transducer face. Future work includes development of an array for adapting these modifications to a 6 mm diameter endoscope probe.

Echocardiography, Transesophageal↗
PubMed2001

Adverse events, including death, associated with the use of 1,4-butanediol.

BACKGROUND: 1,4-Butanediol is an industrial solvent that, when ingested, is converted to gamma-hydroxybutyrate, a drug of abuse with depressant effects, primarily on the central nervous system. After reports of toxic effects of gamma-hydroxybutyrate and its resultant regulation by the federal government, 1,4-butanediol and gamma-butyrolactone, another precursor of gamma-hydroxybutyrate and an industrial solvent, began to be marketed as dietary supplements. We investigated reports of toxic effects due to the ingestion of 1,4-butanediol and reviewed the related health risks. METHODS: From June 1999 through December 1999, we identified cases of toxic effects of 1,4-butanediol involving patients who presented to our emergency departments with a clinical syndrome suggesting toxic effects of gamma-hydroxybutyrate and a history of ingesting 1,4-butanediol and patients discovered through public health officials and family members. We used gas chromatography-mass spectrometry to measure 1,4-butanediol or its metabolite, gamma-hydroxybutyrate, in urine, serum, or blood. RESULTS: We identified nine episodes of toxic effects in eight patients who had ingested 1,4-butanediol recreationally, to enhance bodybuilding, or to treat depression or insomnia. One patient presented twice with toxic effects and had withdrawal symptoms after her second presentation. Clinical findings and adverse events included vomiting, urinary and fecal incontinence, agitation, combativeness, a labile level of consciousness, respiratory depression, and death. No additional intoxicants were identified in six patients, including the two who died. The doses of 1,4-butanediol ingested ranged from 5.4 to 20 g in the patients who died and ranged from 1 to 14 g in the nonfatal cases. CONCLUSIONS: The health risks of 1,4-butanediol are similar to those of its counterparts, gamma-hydroxybutyrate and gamma-butyrolactone. These include acute toxic effects, which may be fatal, and addiction and withdrawal.

Adult↗
PubMed2001

Real-time three-dimensional intracardiac echocardiography.

Using catheter-mounted 2-D array transducers, we have obtained real-time 3-D intracardiac ultrasound (US) images. We have constructed several transducers with 64 channels inside a 12 French catheter lumen operating at 5 MHz. The transducer configuration may be side-scanning or beveled, with respect to the long axis of the catheter lumen. We have also included six electrodes to acquire simultaneous electrocardiograms. Using an open-chest sheep model, we inserted the catheter into the cardiac chambers to study the utility of in vivo intracardiac 3-D scanning. Images obtained include a cardiac four-chamber view, mitral valve, pulmonic valve, tricuspid valve, interatrial septum, interventricular septum and ventricular volumes. We have also imaged two electrophysiological interventional devices in the right atrium, performed an in vitro ablation study, and viewed the pulmonary veins in vitro.

Animals↗
PubMed2001

Droperidol vs. prochlorperazine for benign headaches in the emergency department.

OBJECTIVE: To compare the efficacy of droperidol with that of prochlorperazine for the treatment of benign headaches in emergency department (ED) patients. METHODS: Prospective, randomized clinical trial in an urban ED. Patients were given either droperidol, 5 mg intramuscular (IM) or 2.5 mg intravenous (IV), or prochlorperazine, 10 mg IM or 10 mg IV. Measurements included side effects and the patient's pain perception as measured on a 100-mm visual analog scale (VAS) at baseline, 30, and 60 minutes after the medication was given. Data were analyzed using chi-square, two-tailed t-tests, and two-way analysis of variance (ANOVA) when appropriate. RESULTS: During an eight-month period, 168 patients were enrolled. Eighty-two (48.8%) of the patients received droperidol; 86 (51.2%) received prochlorperazine. In the droperidol group, 49 (59.6%) received IM administration and 33 (40.4%) IV. In the prochlorperazine group, 57 (66.3%) received IM administration and 29 (33.7%) IV. Sixty minutes after the medication, the mean decrease in the VAS scores was 81.4% for droperidol and 66.9% for prochlorperazine (p = 0.001). At 30 minutes, 60.9% of the patients receiving droperidol and 44.2% of the patients receiving prochlorperazine had obtained at least a 50% reduction in their VAS scores (p = 0.09). At 60 minutes, 90.2% of the patients receiving droperidol and 68.6% of the patients receiving prochlorperazine had at least a 50% reduction in their VAS scores (p = 0.017). No difference between IM dosing and IV dosing was detected. Side effects, including dystonia, akathisia, and decreased level of consciousness, were seen in 15.2% of the patients receiving droperidol and 9.61% of the patients receiving prochlorperazine. No significant or persisting morbidity was detected. CONCLUSIONS: Droperidol was more effective than prochlorperazine in relieving pain associated with benign headaches.

Adult↗
PubMed2000

Phase II trial evaluating triplet chemotherapy using gemcitabine, paclitaxel, and carboplatin in the treatment of patients with advanced non-small cell lung cancer.

The purpose of this study was to evaluate the combination of gemcitabine, paclitaxel, and carboplatin in patients with advanced non-small cell lung cancer. Previously untreated patients with stage IIIB or IV non-small cell lung cancer were enrolled into this trial. Sixty-nine patients from the phase II portion and eight patients from the phase I portion were treated with gemcitabine 1,000 mg/m2 intravenously on days I and 8, paclitaxel 200 mg/m2 as a 1-hour infusion on day 1, and carboplatin at an area under the curve of 5.0 intravenously on day 1. Treatment courses were repeated every 21 days. The phase II component of the study was completed at 13 community-based practices in the Minnie Pearl Cancer Research Network. Thirty-four of 71 fully evaluable patients had an objective response (48%, two complete and 32 partial responses). Twenty-five patients (35%) were stable and 12 (17%) progressed. The median response duration was 6 months (range, 3 to 14 months) and the median survival was 9.9 months, with 1- and 2-year survival rates of 47% and 21%, respectively. The combination of gemcitabine, paclitaxel, and carboplatin has been shown to be safe and effective; thus, this three-drug regimen will be compared with a standard two-drug regimen, paclitaxel/carboplatin, in a phase III study.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

Phase I/II trial of paclitaxel by 1-hour infusion, carboplatin, and gemcitabine in the treatment of patients with advanced nonsmall cell lung carcinoma.

BACKGROUND: The combination of paclitaxel and carboplatin is widely used in the treatment of patients with advanced nonsmall cell lung carcinoma. In this Phase I/II study the authors evaluated the feasibility, toxicity, and efficacy of adding a third active antineoplastic agent, gemcitabine, to the paclitaxel/carboplatin combination for the treatment of patients with advanced nonsmall cell lung carcinoma. METHODS: Patients with advanced (AJCC Stage IIIB or IV) nonsmall cell lung carcinoma previously untreated with chemotherapy were eligible for this trial. The maximum tolerated doses, determined in the Phase I trial and subsequently used in the Phase II trial, were: paclitaxel, 200 mg/m2, as a 1-hour infusion on Day 1; carboplatin, at area under the curve dose of 5.0 intravenously (i.v.), on Day 1; and gemcitabine, 1000 mg/m2 i.v., on Days 1 and 8. Treatment courses were repeated every 21 days. The Phase II study was conducted in 13 community-based practices in the Minnie Pearl Cancer Research Network; 77 patients were treated between December 1996 and September 1997. RESULTS: Thirty-four of 77 patients (44%) in the Phase II trial had major responses (partial responses, 32 patients and complete responses, 2 patients). An additional 25 patients (33%) had stable disease or minor response; only 23% of patients progressed or were removed from study at or prior to first reevaluation. The median survival was 9.4 months, with a 45% actuarial 1-year survival rate. Myelosuppression was the most common toxicity, with Grade 3/4 NCI Common Toxicity Criteria leukopenia and thrombocytopenia in 49% and 45% of patients, respectively. However, only 11 patients (14%) required hospitalization for neutropenia/ fever, and none had bleeding complications. Grade 3/4 nonhematologic toxicities included fatigue (41%), arthralgias/myalgias (26%), peripheral neuropathy (8%), nausea/emesis (6%), and hypersensitivity reactions (4%). There was one treatment-related death due to sepsis. CONCLUSIONS: This three-drug regimen is active and has acceptable toxicity in patients with advanced nonsmall cell lung carcinoma. Myelosuppression, particularly thrombocytopenia, is increased in comparison to the paclitaxel/carboplatin regimen. Fatigue also may be increased, but other nonhematologic toxicities are not altered substantially by adding gemcitabine. Although the response rate and median survival are improved modestly compared with our previous experience with paclitaxel/carboplatin, definitive conclusions regarding the efficacy of this regimen await the completion of randomized trials.

Adult↗
PubMed1999

Living with cerebral palsy and tube feeding: A population-based follow-up study.

OBJECTIVES: To assess the impact of surgically placed feeding tubes on children with severe cerebral palsy (CP) and their families and to determine the survival of these children after initiation of tube feeding (TF). METHODS: Virtually all children from Nova Scotia who had gastrostomy or jejunostomy procedures between the years 1980 and 1998 and who had been diagnosed with CP were identified. Caretakers of those children who had TF initiated in the last 8 years were evaluated by using a semi-structured interview. Names of children who had not had recent follow-up visits were submitted to the provincial Vital Statistics office to determine whether they had died. Data from patients who were tube-fed between 1980 and 1989 were then used in combination with data from the more recent cases to create a survival curve. RESULTS: A total of 61 children were identified; 16 had died. Forty of 45 eligible families were interviewed; 90% were pleased with the effect of TF on their child and family life. Negative reports were associated with increased stress related to feeding. Survival rates after gastrostomy and/or jejunostomy were 83% after 2 years and 75% after 7 years. CONCLUSIONS: In children with severe CF, initiation of TF improved the quality of life for both the child and family in 90% despite frequent minor complications.

Activities of Daily Living↗
PubMed1999

Orthodontic correction of a class III malocclusion in an adolescent patient with a bonded RPE and protraction face mask.

A case report of a 14-year-old Hispanic male with a Class-III skeletal profile and dental malocclusion with a long mandibular body and ramus and retrusive maxilla. The patient was initially referred for a surgical evaluation for a LeFort I maxillary advancement, but he wanted to avoid surgery. The Class-III malocclusion was corrected with a bonded rapid palatal expander and a maxillary protraction mask followed by nonextraction orthodontic treatment. A Class-I molar and canine relationship was achieved, and the facial profile improved. This case report demonstrates the orthodontic correction of a Class-III malocclusion in an adolescent patient with a bonded rapid palatal expander and protraction face mask. This case was presented to American Board of Orthodontics as partial fulfillment of the requirements for the certification process conducted by the Board.

Adolescent↗
PubMed1999

Evaluation of the consolidation period during osteodistraction using computed tomography.

The use of distraction osteogenesis offers an alternative approach to the correction of craniofacial deformities. However, little is known with respect to the appropriate length of the consolidation period for the newly formed bone. The objective of this study was to evaluate, by quantitative computed tomography, the regenerate bone produced during osteodistraction of the dog mandible at three different consolidation times. Twelve skeletally mature male beagle dogs were equally separated into three experimental groups. Each dog underwent 10 mm of bilateral distraction osteogenesis to lengthen the mandible. After the distraction period, the bone was allowed to consolidate for 4, 6, or 8 weeks, at which time the animals were sacrificed and the mandibles harvested for computed tomographic imaging. The results demonstrate a significantly lower mean bone density of the regenerate in the 4 week group when compared with either the 6 or 8 week groups (P < .01). There was no significant difference, however, in mean bone density between the 6 and 8 week groups.

Animals↗
PubMed1999

Immunization practices and beliefs of physicians in suburban Cook County, Illinois.

This study was conducted to ascertain the vaccination beliefs and practices of physicians who provide care for low income children. Sixty-two (56.9%) of a sample of 109 physicians in suburban Cook County, Illinois responded to a mail survey. A majority of physicians reported a willingness to immunize during well child care, follow-up, and chronic illness visits; yet, a substantial lack of willingness to immunize given certain acute mild illnesses was reported. Twenty-six percent of providers did not routinely identify children who were behind in immunizations and only 16% had completed a chart audit in the past three years. Seventy-four percent were willing to provide all shots needed at a single visit. Misconceptions regarding true contraindications was found among the group. Missed well child visits were identified as the greatest barrier to complete immunization. Improvements in vaccination rates are expected if physicians utilize all types of medical encounters to monitor the immunization status of patients and provide vaccines using only true medical contraindications.

Adult↗
PubMed1999

A preschool immunization project to enhance immunization levels, the public-private relationship, and continuity of care.

This study was conducted to determine whether implementing a program aimed at providing a variety of incentives to physicians who provide immunizations to preschool-aged children would help to improve immunization rates and reduce fragmented care for patients. Twenty physicians from 14 private practices that provide care to preschool-aged children from low income families in suburban Cook County, Illinois participated in the project. A randomly selected subset of patient case records from the physicians' offices were audited after the implementation of the project to determine the immunization status of children in the practices and the nature of services provided. These 310 records of children under three years of age who were treated between 1991-1994 (the intervention sample) were compared to 310 charts from a 1988-1990 cohort of records (baseline sample). The groups did not differ on race or gender; however, significantly more families in the 1988 through 1990 cohort of children under 3 years of age were insured privately when compared to the 1991 through 1994 cohort. Seventy percent (218) of the records in the intervention sample were up to date for age on immunizations compared to 45% (141) of the baseline records, reflecting a statistically significant difference (p < .00001). The intervention sample showed significantly more well child visits where immunizations were given and follow up visits where immunizations were given when compared to the baseline sample. Physicians completed surveys before and after implementation of the project. They were questioned about their knowledge and practices regarding immunizations as well as their opinion of specific project components. All of the physicians viewed the project as an effective means to improve immunization services to low income children. The project demonstrates a potential means of enhancing immunization levels and continuity of care among preschool-aged children. It also highlights the workable nature of the partnership between public and private sectors.

Child Health Services↗