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Biomedical subjects

T W Clark

Publications and source records attributed to T W Clark.

At least 19 recordsLinked to original sources
PubMed2002

Decreased youth tobacco use in Massachusetts 1996 to 1999: evidence of tobacco control effectiveness.

OBJECTIVE: To evaluate tobacco control in Massachusetts through examining trends in youth tobacco use from 1996 to 1999. DESIGN: Data are from the 1996 and 1999 Massachusetts Prevalence Study survey of public school students in the state. PARTICIPANTS: Participants consisted of 6800 (1996) and 6980 (1999) students in Massachusetts public school grades 6-12 (approximate ages 11-18 years). MAIN OUTCOME MEASURES: Outcomes are changes in lifetime and current (past month) cigarette, cigar, and smokeless tobacco. RESULTS: In grades 7-12, there were significant decreases in lifetime (48.3% to 41.9%) and current (30.7% to 23.7%) cigarette use, smokeless tobacco use (lifetime 16.5% to 9.9%; current 4.55 to 2.6%), and current cigar use (12.2% to 8.6%). Decreases occurred for both male and female 7-8th graders. In grades 9-12 decreases were somewhat greater for females than males. Trends for grades 8, 10, and 12 were compared to those seen nationally and in the northeast region in the Monitoring the Future study. For the pooled grades the decreases for cigarettes were greater than those seen nationally or in the northeast region. CONCLUSIONS: Results support the effectiveness of the comprehensive Massachusetts Tobacco Control Program. The increasing tobacco rates in the first half of the 1990s have been dramatically reversed. These results suggest that programme efforts should be supported or even expanded in order to decrease further the state's rates of youth tobacco use. The findings suggest that other states may learn useful lessons from Massachusetts' successes.

Adolescent↗
PubMed2001

Transjugular liver biopsy with use of the shark jaw needle: diagnostic yield, complications, and cost-effectiveness.

PURPOSE: Obtaining transjugular liver biopsy specimens with use of single-use needle systems is expensive, whereas biopsy specimens obtained with use of reusable needle systems are frequently associated with inadequate core specimens. The authors report their experience with the reusable Cook Shark Jaw biopsy needle, including diagnostic yield, complications, and cost-effectiveness. MATERIALS AND METHODS: A retrospective audit was performed of a cohort of 134 patients who underwent 136 transjugular liver biopsies with use of a reusable 16-gauge Shark Jaw needle during a 30-month period. Specimen adequacy and complication rates were assessed and direct costs of expendable components calculated. Cost-effectiveness was expressed as cost-per-successful biopsy. RESULTS: Biopsies were technically successful in 126 of 136 (93%) patients, with diagnostic histologic core specimens obtained in 124 of 126 (98%) patients, for an overall success rate of 91%. Complications included capsular penetration in six (4.4%) patients, cardiac arrhythmia in two (1.5%) patients, and puncture site hematoma or bleeding in 10 (7.4%) patients. Three tract embolizations were performed for capsular penetration. No instances of subcapsular hematoma, hemoperitoneum, or sepsis occurred, and no deaths were attributed to the procedure. The cost of expendable components totaled $103 per biopsy, corresponding to a cost-effectiveness of $113/successful biopsy. CONCLUSION: Transjugular liver biopsy specimens obtained with use of the Shark Jaw needle have a diagnostic yield comparable to those obtained with use of single-use biopsy systems, at a substantially lower cost with no increase in serious complications.

Adult↗
PubMed2001

Predictors of long-term patency after femoropopliteal angioplasty: results from the STAR registry.

PURPOSE: To identify variables predictive of long-term patency after femoropopliteal angioplasty. MATERIALS AND METHODS: The primary patency of 219 limbs in 205 patients from a multicenter registry who underwent femoropopliteal angioplasty between January 1, 1992, and December 31, 1994, was prospectively monitored with a combination of angiography, noninvasive hemodynamic testing, and clinical outcome. Patient demographic, angiographic, and hemodynamic variables were examined alone and in combination to determine effect on long-term primary patency. Each limb was graded as Category 1-4 according to the American Heart Association (AHA) criteria for arterial lesions, and differences in outcome for each category were examined. Primary patency and intergroup analysis were determined with use of the Kaplan-Meier method and log-rank test, respectively. Cox proportional hazards models were used to calculate relative risks for predictive variables. RESULTS: Primary patency rates for all limbs (on an intent-to-treat basis) at 12, 24, and 36 months were 87% +/- 3%, 80% +/- 3%, and 69% +/- 5%, respectively. Primary patency at 48 and 60 months was 55% +/- 7%. Poor tibial runoff (single tibial vessel with 50%-99% stenosis or occlusion) was most predictive of occlusion (relative risk 8.5, P <.0001). The presence of diabetes or renal failure was associated with lower long-term patency (relative risk 5.5 and 4.0, P <.0001 and.0002, respectively). Long-term patency was higher with AHA Category 1 lesions (P =.006), and no significant difference in patency was observed between Category 2 and 3 lesions (P =.65). A multivariate Cox proportional hazards model showed only the stratified runoff score and the presence of diabetes to be significant determinants of long-term patency. CONCLUSION: Poor tibial runoff is most predictive of lower long-term patency rates. Diabetes is also independently associated with lower long-term patency rates. The criteria that distinguish Category 2 and 3 lesions do not predict differences in long-term patency, nor do they serve to identify lesions best treated with surgical bypass. This suggests that indications for femoral angioplasty can be extended to include longer and more complex Category 3 lesions.

Adolescent↗
PubMed2001

Risk factors for liver abscess formation after hepatic chemoembolization.

PURPOSE: To assess the frequency and risk factors for liver abscess after hepatic chemoembolization. MATERIALS AND METHODS: The authors performed retrospective analysis of 397 chemoembolization procedures in 157 patients. All patients received prophylactic intravenous antibiotics before the procedure and 5 days of oral antibiotics after the procedure. The association between abscess formation and risk factors was determined with use of chi(2) analysis and the Fisher exact test and expressed as an odds ratio. RESULTS: Liver abscess occurred in seven of 157 patients (4.5%) after eight of 397 procedures (2.0%) at a mean of 19 d +/- 7 after chemoembolization. No patients had neutropenia. Organisms isolated reflected intestinal flora. Six patients required percutaneous drainage for 35 d +/- 29. The seventh patient required drainage for the remainder of life as a result of a nonhealing biliary fistula. Three of 24 patients with neuroendocrine tumors had abscesses (12.5%; odds ratio, 4.6; 95% CI, 0.96-22.1; P =.07), as did three of 14 patients with gastrointestinal sarcomas (21%; odds ratio, 9.5; 95% CI, 1.9-47.8; P =.016), and one of two with pancreatic adenocarcinoma. Six of the seven patients with abscesses underwent a Whipple procedure before chemoembolization. Only one patient with a history of a Whipple procedure did not develop an hepatic abscess. In the absence of a bilioenteric anastomosis, abscess occurred in only one of 150 patients (0.7%), or one of 383 procedures (0.3%). The odds ratio for liver abscess among patients with a bilioenteric anastomosis was 894 (95% CI, 50-16,000; P <.0001). CONCLUSION: Earlier bilioenteric anastomosis is the major determinant of liver abscess formation after hepatic chemoembolization. The prophylaxis regimen used failed to prevent abscess formation in patients with earlier bilioenteric anastomosis.

Adult↗
PubMed2001

Sarcomas metastatic to the liver: response and survival after cisplatin, doxorubicin, mitomycin-C, Ethiodol, and polyvinyl alcohol chemoembolization.

PURPOSE: To evaluate the response to and survival after chemoembolization with cisplatin, doxorubicin, mitomycin-C, Ethiodol, and polyvinyl alcohol for patients with sarcomas metastatic to the liver that are surgically unresectable. MATERIALS AND METHODS: Sixteen patients were treated. Primary tumors included 11 gastrointestinal leiomyosarcomas, two splenic angiosarcomas, one leiomyosarcoma of the broad ligament, one leiomyosarcoma of the inferior vena cava, and one malignant fibrous histiocytoma of the colon. Chemoembolization with cisplatin, doxorubicin, mitomycin-C, Ethiodol, and polyvinyl alcohol particles was performed 1-5 times at approximately monthly intervals (mean, 2.8). Pre- and posttreatment cross-sectional imaging was performed 1 month after completion of treatment and then every 3 months. Thirty-day response was graded according to World Health Organization/Eastern Cooperative Oncology Group criteria. Survival was calculated with use of Kaplan-Meier analysis. RESULTS: Two patients (13%) exhibited partial morphologic response, 11 patients (69%) were morphologically stable, and three (19%) demonstrated progression of disease 30 days after completion of treatment. Among the 13 responders, two underwent partial hepatectomy after initial treatment. Seven developed intrahepatic progression at a mean of 10 months and a median time of 8 months. The remaining four patients had no documented intrahepatic progression at the time of last imaging follow-up. Nine patients developed extrahepatic progression at a mean time of 6.3 months and a median time of 6 months, of whom four underwent additional surgical resection. Response to therapy was based on time of first intervention. Cumulative survival from time of diagnosis with use of Kaplan-Meier analysis was 81% at 1 year, 54% at 2 years, and 40% at 3 years. Median survival time was 20 months. Cumulative survival from initial chemoembolization was 67% at 1 year, 50% at 2 years, and 40% at 3 years, with a median survival time of 13 months. The thirty-day mortality rate was zero. CONCLUSION: Durable tumor response with chemoembolization is possible in this form of metastatic disease, which is highly resistant to systemic chemotherapy.

Chemoembolization, Therapeutic↗
PubMed2001

Percutaneous radiofrequency ablation of liver tumors with the LeVeen probe: is roll-off predictive of response?

PURPOSE: The LeVeen radiofrequency (RF) probe uses roll-off of electrical impedance as the endpoint for RF cautery of hepatic tumors. The purpose of this study is to determine the relation of roll-off to local control of hepatic tumors. MATERIALS AND METHODS: Twenty hepatic tumors, including 10 hepatomas and 10 metastases, were treated. Lesions ranged from 1.4 cm to 6.0 cm in diameter; 13 (57%) were smaller than 3.0 cm. Each lesion was ablated with use of the LeVeen 15-gauge RF needle according to the manufacturer's protocol. Five patients underwent chemoembolization the day before. Patients were followed up with contrast-enhanced computed tomography or magnetic resonance imaging at 1 month and every 3 months thereafter. RESULTS: Among the 20 lesions, roll-off was achieved at all burn locations in 11 (55%), no burn locations in eight (40%), and two of three burn locations in one (5%). Roll-off was observed in all patients who had undergone chemoembolization the day before. Six local recurrences occurred, five after RF ablation without roll-off and one after RF ablation with roll-off. According to life-table analysis, the local recurrence rate at 6 months without roll-off was 43% and with roll-off was 15% (P =.024; OR = 8.3; 95% CI = 0.93-66). CONCLUSION: Roll-off is a significant predictor of local control after RF ablation. Strategies to enhance roll-off, such as concurrent embolization, may be important to optimize the therapeutic effect of this device.

Catheter Ablation↗
PubMed2000

Tobacco use among Massachusetts youth: is tobacco control working?

BACKGROUND: This paper examines whether the Massachusetts Tobacco Control Program is affecting the rates of smoking and smokeless tobacco use among Massachusetts' youth. METHODS: School survey data from the Massachusetts Prevalence Study were analyzed to estimate differences between 1993 and 1996 rates of youth cigarette and smokeless tobacco use, attitudes toward smoking, and awareness of cigarette ads and promotions of antismoking messages. RESULTS: Lifetime and Current Smoking rates declined significantly among middle school males, contrasting with stable national trends. Among girls in this age group, Lifetime and Current Smoking did not change significantly. Hispanic middle school students exhibited a significant decline in Lifetime Use. There were no significant changes in Lifetime or Current Smoking rates among high school students. Lifetime use of smokeless tobacco declined among middle school students while Current Use declined among both middle and high school students. Students reported declines in awareness of cigarette ads or promotions and increases in awareness of antismoking messages. CONCLUSIONS: These results provide evidence for cautious optimism regarding the impact of tobacco control, but indicate that these efforts should begin earlier and that additional research is needed to understand and address the problems of tobacco use by girls.

Adolescent↗
PubMed2000

Vernal pool conservation in connecticut: an assessment and recommendations.

Vernal pools, a variety of ephemeral wetlands, are threatened in many areas of the United States. As habitat fragmentation and degradation increase, some vernal pool amphibian species are declining in numbers. Uneven implementation of state regulations further hampers effective conservation. To prevent further species decline and vernal pool loss, we evaluated alternatives for improving vernal pool conservation. We used transcripts from a recent vernal pool conference, interviews with members of relevant interest groups, and a literature review to determine opportunities for and constraints on improving vernal pool conservation policy. Participants from different interest groups had very diverse views about appropriate protection strategies. We have examined these different perspectives and alternatives and offer policy recommendations on both the state and local level. These recommendations can foster awareness of vernal pools as unique habitats, increase protection of these areas, and expand citizen participation in the vernal pool regulatory process.

Journal Article↗
PubMed2000

Endovascular stenting in superior vena cava syndrome: utility of a through-and-through guidewire technique.

OBJECTIVE: To describe an ancillary technique when a conventional femoral approach to superior vena cava (SVC) stent placement is not feasible because of buckling of balloon catheters or stent-deployment systems during device advancement. PATIENTS AND METHODS: Three patients in whom device advancement across the SVC lesion from a femoral or axillary approach was unsuccessful were managed by accessing the right jugular vein; SVC lesions were crossed from an antegrade direction, and the jugular guidewire was secured at the femoral access site to create a through-and-through guidewire. RESULTS: Countertraction on the through-and-through guidewire during stent placement and dilation permitted unhindered advancement of stent delivery systems and catheters across the SVC. Technical and clinical success was achieved in each patient with relief of SVC syndrome within 24-72 hours. Survival ranged from 26 to 137 days. CONCLUSION: A through-and-through guidewire technique is useful when stenting a highly stenotic or thrombosed SVC in patients with superior vena cava syndrome.

Adenocarcinoma↗
PubMed1998

Cine phase-contrast MR to assess portal blood flow in a 10-year-old girl with abdominal aortic coarctation: a case report.

We report the case of a 10-year-old girl with repaired abdominal aortic coarctation in whom chronic mesenteric ischemia was clinically suspected. Cine phase-contrast magnetic resonance (MR) was used to determine the difference between fasting and postprandial portal blood flow. Fasting flow rates in the portal vein were normal. After a meal, blood flow in the portal vein increased 226% over the fasting state, showing normal augmentation. To the best of our knowledge, this is the first application of this technique to a pediatric setting.

Aorta, Abdominal↗
PubMed1997

Stratification of prostate-specific antigen level and results of transrectal ultrasonography and digital rectal examination as predictors of positive prostate biopsy.

OBJECTIVE: To determine which of several variables--age, serum level of prostate-specific antigen (PSA), findings of transrectal ultrasonography (TRUS) and findings of digital rectal examination (DRE)--are the best predictors of positive prostate biopsy results. SETTING: An urban, university-affiliated tertiary care hospital. PATIENTS: a cohort of 1330 consecutive men referred to the diagnostic imaging department for TRUS and TRUS-guided prostate biopsy. Each patient was referred after examination by a urologist because of clinical suspicion of prostate cancer. METHODS: All of the men had undergone prior determination of serum level of PSA. Repeat DRE was performed at the time of imaging. The variables age, PSA level, TRUS findings and DRE findings were tested aline and in combination as predictors of positive biopsy results by means of logistic regression analysis. A summary of percentage risk for positive biopsy results was constructed for each combination of statistically significant variables, stratified for age. RESULTS: Cancer was detected in 541 men (40.7%). A strong correlation was observed between serum PSA level and the likelihood of positive biopsy result (p < 0.001). Of 402 men with normal age-specific PSA, 109 (27.1%) had positive biopsy results. Of 403 men with PSA of 10 ng/mL or more, 233 (57.8%) had cancer. The level of serum PSA was also related to the number of prostate sextants harbouring cancer (p < 0.001). TRUS findings at the time of biopsy were a strong predictor of cancer of the PSA level was abnormal (p < 0.001). DRE results alone did not correlate with positive biopsy results, regardless of age, PSA level of TRUS findings. CONCLUSIONS: Men in whom there is a clinical concern for prostate cancer should undergo prostate biopsy if there is any elevation of age-specific PSA, particularly if the findings of TRUS are also abnormal. Because DRE alone was not predictive of biopsy outcome, algorithms for prostate cancer detection that rely on abnormal DRE results to identify men who should undergo biopsy will miss a significant number of cancers.

Aged↗
PubMed1996

Improving the detection of radiographically occult ankle fractures: positive predictive value of an ankle joint effusion.

OBJECTIVE: To assess the value of an ankle effusion on plain radiographs as a predictor of radiographically occult fracture after acute ankle trauma. PATIENTS: Consecutive patients with acute ankle trauma and radiographic evidence of an ankle joint effusion. Patients were excluded if ankle trauma was sustained more than 48 h previously or if a fracture was visible on initial photographs. METHODS: All subjects (n = 26) underwent computed tomography (CT) of the ankle in sagittal and coronal planes. Ankle effusion size was measured from initial lateral ankle radiographs. RESULTS: Twelve patients (46%) had radiographically occult fractures identified with CT. Fracture sites included: posterior or lateral malleoli (n = 4), calcaneus (n = 1), or talus (n = 7). Ankle effusion size was 11.2 mm in the group without fracture and 17.1 mm in the group with fracture (P < 0.0001). The positive predictive value of an effusion 15 mm or greater was 83%. CT detected significant soft-tissue injuries in four (15%) patients including peroneal retinaculum tear (n = 1), anterior talofibular ligament avulsion (n = 1), and tears of the peroneus longus (n = 1) and tibialis posterior (n = 1) tendons. CONCLUSIONS: The presence of a large ankle effusion of radiographs after acute ankle trauma suggests an underlying fracture. An ankle effusion of > or = 15 mm is a reasonable threshold to prompt additional imaging. Computed tomography provides good visualization of subtle bone injuries and may detect clinically imported soft-tissue injuries.

Adult↗
PubMed1996

Using tomography to diagnose occult ankle fractures.

STUDY OBJECTIVES: To determine the incidence of occult ankle fractures and to determine whether an ankle effusion identified radiographically correlated with the presence of an occult fracture. METHODS: Attending physicians in the emergency department of a university hospital prospectively identified patients with acute ankle injuries that produced ecchymosis or edema over two or more major ligaments of the ankle. Plain radiographs of these patients demonstrated ankle effusions without fractures. A consecutive sample of patients with acute ankle injuries was selected. Thirty-six of 1,151 patients were eligible to enter the study; 2 of these patients subsequently were excluded from the data analysis. All eligible patients underwent plain ankle tomography at 3-mm intervals in the coronal and sagittal planes. The types and frequencies of occult ankle fractures identified on plain film tomography were noted. The distention of the ankle joint capsule of enrolled patients was measured to determine if the degree of effusion correlated with the presence of an occult fracture. RESULTS: The minimum incidence of occult fractures in the general population with ankle injuries was 1%. Twelve of 34 patients (35%) with acute, severe injuries had occult fractures. Depending on the size, an effusion was correlated with the presence of an occult fracture in 35% to 85% of the study population. CONCLUSION: Plain film tomography should be used when evaluating ankle injuries if both edema or ecchymosis over two or more stabilizing ligaments and radiographic evidence of an effusion are present simultaneously.

Acute Disease↗
PubMed1995

Detection of radiographically occult ankle fractures following acute trauma: positive predictive value of an ankle effusion.

OBJECTIVE: The purpose of our study was to determine if the presence of an ankle effusion on plain radiographs after acute ankle trauma is predictive of occult ankle fracture when no fracture is visible on the standard radiographic series. SUBJECTS AND METHODS: The ankle radiographs of 1153 patients with acute ankle trauma were examined for fracture and for the presence and extent of anterior and posterior capsular distension. Patients with ankle effusions but no detectable fracture subsequently underwent sagittal and coronal complex-motion tomography. RESULTS: Eleven of 33 patients with ankle effusions and otherwise normal plain radiographs had occult fractures identified with tomography. The fracture sites were as follows: osteochondral fracture of talar dome (n = 4), neck of talus (n = 1), medial malleolus (n = 1), anterior tibial rim (n = 1), posterior tibial rim (n = 1), tibial plafond (n = 1), lateral malleolus (n = 1), and anterior process of calcaneus (n = 1). The radiographic size of an ankle effusion was predictive of occult fracture. An ankle effusion measuring 13 mm or more in anterior plus posterior capsular distension had an 82% sensitivity and 91% specificity for underlying fracture in our series. The positive predictive value of an ankle effusion 13 mm or greater was 82%. CONCLUSION: The presence of an ankle effusion on plain radiographs following acute ankle trauma is suggestive of an underlying fracture. An ankle effusion of 13 mm or greater in total capsular distension has a positive predictive value of 82% for occult fracture and is a reasonable threshold to prompt additional imaging.

Adolescent↗
PubMed1992

Prevention of stress gastritis with tissue preservation solution.

Stress gastritis frequently occurs in association with shock or sepsis. Gastric mucosal ischemia appears to be a key feature in these critically ill patients. The University of Wisconsin cold preservation solution (UWS) is an isoosmolar, nonglucose-based perfusate that minimizes hypothermia-induced cell swelling and prevents intracellular acidosis and oxygen-free radical injury, while providing high energy substrates for donor organs. In a prospective, single-blind study, 18 similar Sprague-Dawley rats were randomly divided to receive only 5 per cent dextrose and water (D5W) (Group 1) or a 50 per cent solution of D5W+UWS (Group 2) for 72 hours. At the end of 72 hours the animals were stressed by the cold-restraint model. The mean number of ulcers for Group 2 was nearly half that of Group 1. Also, Group 2 had a significantly lower mean total ulcer length (P less than 0.005) and ulcer index (P less than 0.05). Most of Group 2 had mild gastritis changes (grade 0 to 1), while more than half of Group 1 had severe gastritis (grade 3). Gastric mucosal pH was similar for both groups. Topically applied UWS appears to reduce the severity and incidence of stress gastritis in this experimental model. Because mucosal pH values were similar, it is thought that UWS may alter the effects of gastric mucosal ischemia at a cellular level.

Adenosine↗