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Biomedical subjects

R B Smith

Publications and source records attributed to R B Smith.

At least 37 records · Page 2Linked to original sources
PubMed1999

Cervical lymph node metastases and squamous cell carcinoma of the lip.

BACKGROUND: Squamous cell carcinoma of the lip generally has a favorable outcome. The chance of long-term survival is significantly reduced if lymph node metastases develop. Any features that could identify patients having increased risks of occult lymph node metastases would allow more aggressive treatment and, possibly, a better outcome. METHODS: A chart review of lip cancer from this institution identified 1001 patients with squamous cell carcinoma of the lip. This database was used to identify the characteristics that are associated with occult lymph node metastases. RESULTS: Delayed cervical lymph node metastases developed in 40 patients. No significant differences were noted in the frequency of delayed lymph node metastases according to gender, lip subsite, or age less than 40 years. Significant differences were noted in association with the tumor size, tumor differentiation, and local recurrence. CONCLUSIONS: Elective cervical lymphadenectomy is justifiable for higher grade tumors and for locally recurrent tumors. An increase in delayed metastases was observed in patients with tumors greater than 3 cm, but the proportion is not great enough to justify elective neck dissections.

Adult↗
PubMed1999

Cortical evoked potentials in the ruptured anterior cruciate ligament.

The sensory role of the intact and ruptured anterior cruciate ligament was studied by the use of cortical evoked potentials during arthroscopy. This showed a response from the intact ligament in four patients that was reproducible. This response was consistent with those obtained from stimulation of the ipsilateral posterior tibial nerve. No response was elicited from either the femoral or tibial stump of ruptured ligaments using the same technique in six patients who had ruptured their anterior cruciate ligament (two femoral and four mid-substance ruptures). We believe that this demonstrates that there is no functional nervous tissue within the anterior cruciate ligament after rupture.

Anterior Cruciate Ligament↗
PubMed1999

Recurrent cutaneous melanoma of the head and neck.

INTRODUCTION: Recurrent cutaneous melanoma is generally regarded as having an extremely poor prognosis, particularly when regional lymph nodes are involved. A few reports have documented long-term survival among those patients treated for regionally recurrent melanoma. METHODS: This article reviews patients at our institution undergoing complete neck dissection for recurrent head and neck melanoma. RESULTS: Twenty-six patients with locoregionally recurrent cutaneous melanoma of the head and neck underwent complete neck dissection with or without parotidectomy. Seventeen of these procedures were for clinically evident cervical lymphadenopathy, whereas 9 of the neck dissections were done electively. Fourteen of the 17 patients with clinical adenopathy were confirmed to have cervical lymph node metastases. Two of the 9 patients who underwent elective neck dissections had pathologic lymph nodes. At 5 years, 38% of the patients with isolated neck recurrences not also having concurrent primary site recurrence were alive without disease. CONCLUSIONS: These results provide further evidence suggesting a benefit in the form of long-term survival or cure for patients receiving aggressive surgical treatment for resectable recurrent head and neck melanoma involving cervical lymphatics in the absence of distant metastases.

Disease-Free Survival↗
PubMed1999

Efficacy of nephron-sparing surgery for renal cell carcinoma: analysis based on the new 1997 tumor-node-metastasis staging system.

PURPOSE: To analyze the experience with nephron-sparing surgery as a treatment modality for renal cell carcinoma (RCC). PATIENTS AND METHODS: Between 1980 and 1997, 146 patients underwent partial nephrectomy at the University of California-Los Angeles Medical Center. A matched group of 125 patients who underwent radical nephrectomy at the same institution between 1986 and 1997 were selected for comparison. Patients were monitored for an average period of 57 months. Patients were staged according to both the 1997 and 1987 tumor-node-metastasis (TNM) staging criteria. Survival data were calculated in terms of both staging criteria. RESULTS: When comparing cancer-specific survival rates for patients with T1 lesions under both the 1987 and 1997 TNM staging criteria, no statistically significant difference in survival was noted (P =.53), although most of the tumors in our series measured < or = 4 cm. Patients with T2 lesions (1997 TNM) demonstrated a significant decrease in survival (66%) when compared with patients with T1 lesions (100%; P <.001). No statistically significant difference in survival for patients with T1 RCC treated with either radical or partial nephrectomy was noted (P =.219). Survival rates of partial and radical nephrectomies for patients with unilateral T1 RCC and a normal contralateral kidney also were not significantly different (P =.53). In contrast, for patients with lesions greater than T1, survival rates were significantly higher with radical versus partial nephrectomy (P =.001). CONCLUSION: Partial nephrectomy has become an effective method of treating T1 RCC lesions as categorized by both the 1987 and the revised 1997 TNM staging criteria. Selected patients with localized unilateral RCC lesions less than 7 cm (ideally, < 4 cm) and a normal contralateral kidney will benefit from partial nephrectomy.

Adult↗
PubMed1999

Accidental veterinary antibiotic injection into a farm worker.

A 29-year-old white male farm worker accidentally injected tilmicosin, a bovine antibiotic, into his finger. He developed temporary pulmonary, gastrointestinal, and neuromuscular symptomatology and a more persistent subjective asthenia.

Accidents, Occupational↗
PubMed1998

Mechanical stability of the AO internal spinal fixation system compared with that of the Hartshill rectangle and sublaminar wiring in the management of unstable burst fractures of the thoracic and lumbar spine.

STUDY DESIGN: A radiographic comparison of the mechanical efficacy of the Hartshill rectangle and that of the AO internal spinal skeletal fixation systems in the management of unstable burst fractures of the thoracic and lumbar spine. OBJECTIVES: To study the restoration and maintenance of normal spinal anatomy after open reduction and internal fixation of unstable burst fractures of the thoracic and lumbar spine. SUMMARY OF BACKGROUND DATA: There are laboratory studies documenting the biomechanical advantages of the AO internal spinal skeletal fixation systems. There have been no previous comparisons of the internal spinal skeletal fixation system with the Hartshill rectangle and sublaminar wiring in matched patient groups. METHODS: Radiographs obtained before surgery, immediately after surgery, and at 2 years after surgery were used to assess the restoration and maintenance of normal spinal anatomy in 14 patients who had undergone stabilization with the Hartshill System and in 12 patients who had undergone internal fixation using the AO internal spinal skeletal fixation system. RESULTS: The initial restoration of normal spinal anatomy was good using both systems. However, on examination 2 years after surgery, it was found that the AO system provided significantly superior maintenance of both middle (P < 0.01) and anterior column anatomy (P < 0.001). CONCLUSION: The AO internal spinal skeletal fixation systems is associated with significantly superior maintenance of spinal anatomy 2 years after surgery.

Bone Screws↗
PubMed1998

Three-dimensional laser imaging system for measuring wound geometry.

BACKGROUND AND OBJECTIVE: A low cost laser imager was designed and fabricated for measurement of wound geometry. METHODS: The accuracy of the imager was validated using reference depressions of known dimensions. Perimeter, area, and volume were compared to planimetric and packing techniques on simulated wound models. RESULTS: Wound tracing and alginate measurement methods required approximately 20 times longer for the reference standards, and 11 times longer for the simulated wounds than with the laser scanning method (LSM). LSM consistently overestimated the reference perimeter by 0.73+/-0.20 cm and the area by 0.98+/-0.62 cm2. Volume estimates were not statistically different. The tracing method underestimated the perimeter by 0.34+/-0.27 cm and the area by 1.07+/-1.09 cm2. Volume measurements by the alginate method were not statistically different. The perimeters of the simulated wounds averaged 1.29+/-0.27 cm greater using the LSM than obtained by the tracing method, and areas greater by 2.02+/-1.30 cm2. Volume scans averaged 1.04+/-0.61 cm3 greater than by the alginate method.

Analysis of Variance↗
PubMed1998

Concomitant aortic and renal artery reconstruction in patients on an intensive antihypertensive medical regimen: long-term outcome.

A beneficial effect in blood pressure control is presumed for patients on an intensive preoperative antihypertensive regimen who undergo empiric renal revascularization. Nonetheless, a noticeable decline in surgical cure rates for hypertension has been recently observed in patients with generalized atherosclerosis. The outcome of patients on multiple preoperative antihypertensive agents who underwent combined aortic and renal artery reconstruction was reviewed. The study population comprised 43 patients who underwent concomitant renal artery and aortic reconstruction for atherosclerotic disease between 1983 and 1995 and who were taking two or more antihypertensive medications and had a serum creatinine of less than or equal to 1.7 mg/dL. Operative management included an aortic reconstruction with either unilateral (n = 22) or bilateral (n = 19) aortorenal bypass or renal endarterectomy (n = 2). Operative mortality was 4.7% (2 of 43). The estimated 5-yr probability of survival was 83% (95% C.I. 0.70, 0.99). Late follow-up data on blood pressure control were available for review in 32 patients at a median follow-up of 37 months. Hypertension was cured in 1 (3%) and improved in an additional 15 (47%) patients. The numbers of antihypertensive medications taken preoperatively (mean = 2.7) declined at late follow-up (mean = 1.6). Notably, the largest reduction was observed with beta blockers (p = 0.006), central sympatholytics (p = 0.041), and angiotensin converting enzyme (ACE) inhibitors (p = 0.052). The number of preoperative antihypertensive medications was not significantly related to survival or to blood pressure improvement. However, uncontrolled preoperative hypertension despite antihypertensive therapy was associated with a favorable blood pressure response to operation (p < 0.001). Patients on an intensive antihypertensive regimen can safely undergo concomitant renal artery and aortic reconstruction for the empiric management of hypertension. Poorly controlled preoperative hypertension in the presence of multiple antihypertensive agents is a favorable marker for improved postoperative blood pressure control.

Aged↗
PubMed1998

Osteomyelitis of the scaphoid with sequestration of the primary ossification centre.

An 8-year-old boy presented with Staphylococcus aureus osteomyelitis affecting the left (non-dominant) scaphoid. Surgical drainage resulted in the expulsion of the primary ossification centre as a sequestrum. Seven years later the wrist function was minimally impaired and X-rays showed complete ossification of the cartilage remnant with a relatively normal scaphoid.

Carpal Bones↗
PubMed1998

Bilateral anterior shoulder dislocations in bench pressing: an unusual cause.

A case of bilateral anterior glenohumeral dislocation in a young weight trainer is presented. The patient, an insurance clerk, had been using a free weight bar in the bench press position and had become tired when the weight on the bar forced his arms into hyperextension in the mid-abducted position. The humeral shaft gradually pivoted on the bench and the humeral heads were slowly dislocated anteriorly by the weight of the bar. Simple closed reduction under sedation was performed and there were no complications. After six weeks in bilateral broad arm slings, with pendulum exercises from two weeks, the patient began to mobilise his arms and he achieved a full range of movements. This unusual mechanism of injury has not previously been reported and we recommend that bench pressing should be performed with a weight that can be "locked" to prevent crushing of the user. Furthermore, the bench should be narrow enough to allow the shoulders to overhang, allowing greater extension in the abducted position without the arm pivoting on the edge of the bench.

Adult↗
PubMed1998

Comparison of two endodontic handpieces during the preparation of root canals in extracted human teeth.

This in vitro study compared and assessed two endodontic handpieces during the preparation of root canals in extracted human teeth. Eighty extracted human teeth, with single root canals, were divided into eight matched groups. They were prepared using Shaper files activated by the MM1500 Sonic Air handpiece (Micro-Mega, Besançon, France) or Excalibur files activated by the W & H Excalibur 969 handpiece (W & H, Bürmoos, Austria). The files were 21 mm or 25 mm in length. When preparing the canals, the files were used either in line with or perpendicular to any canal curvature. Preparation of the canals was carried out using the techniques described in the manufacturers' literature. A variety of parameters were used to compare the handpieces, including canal preparation time, deformation or fracture of instruments, loss of canal length, weight loss from the prepared teeth and the overall postpreparation canal shape. A microradiographic technique was used to produce a tracing record of the pre- and postpreparation canal shape. Both handpieces provided an efficient and easy method of preparing and shaping the root canal with little operator fatigue. The MM1500 Sonic air handpiece took significantly more time (P < 0.001) to prepare the canals than the Excalibur. Few aberrations in the shapes of prepared canals were created by either handpiece. No endodontic file fractured but a few of them were permanently deformed. The effects of two variables--file length and the plane of use of the file--on performance of the handpieces, were also assessed.

Dental Instruments↗
PubMed1997

Comparison of two endodontic handpieces during the preparation of simulated root canals.

The objective of this in vitro study was to compare and assess two endodontic handpieces during the preparation of simulated root canals. One hundred and sixty simulated root canals in clear resin blocks, of two angles and positions of curvature, were prepared using either Shaper files activated by the MM1500 Sonic Air handpiece (Micro-Mega, Besançon, France) or Excalibur files activated by the W & H Excalibur 969 handpiece (W & H, Bürmoos, Austria). Files of 21-mm or 25-mm length were used. When preparing the canals, the files were used either in line with or perpendicular to the canal curvature. Preparation of the canals was carried out using a technique described in the manufacturers' literature. A variety of parameters were used to compare the handpieces, including an assessment of the canal preparation time, the deformation or fracture of instruments, loss of canal length, weight loss from the resin blocks and the overall postpreparation canal shape. Both handpieces provided an efficient and easy method of preparing and shaping the root canal with little operator fatigue. The MM1500 Sonic Air handpiece took significantly more time (P < 0.001) to prepare the canals and was associated with both more loss of working length (P < 0.05) and more loss of weight (P < 0.001). Both handpieces created a high percentage of aberrations in the shapes of prepared canals. The MM1500 Sonic Air handpiece created significantly more aberrations than the Excalibur handpiece (P < 0.05 for zip and elbow, P < 0.05 for danger zone and coronal narrow). The effects of the variables, canal curvature, file length and the plane of use of the file, on the performance of the handpieces, were also assessed.

Acrylic Resins↗
PubMed1997

The impact of social support on gay male couples.

The impact of social support on the relationships of gay male couples is examined. Social support for couples is defined as the availability of people outside the couple perceived as willing to offer resources in a manner that provides assistance and validates the couple's relationship. The sample consisted of 156 cohabiting gay male couples. It was found that social support for the couple is positively correlated with relationship quality. There are promising but not definitive indications that social support for the couple better predicts relationship quality than does social support for the individual. The categories of social support providers having a unique impact on relationship quality were family members and friends.

Family↗
PubMed1997

Alprazolam in young and elderly men: sensitivity and tolerance to psychomotor, sedative and memory effects.

This study was designed to determine whether age influences sensitivity to alprazolam and/or rate of acute tolerance development to the effects of alprazolam. Three treatments were each separated by 4 weeks. Twenty-five young (ages 22-35) and 13 elderly (ages 65-75) men received 2 mg of alprazolam/2 min i.v. Blood samples were obtained over 48 hr, and sedative, psychomotor and memory effects were assessed serially for 12 hr. Clearance was lower (P = .05) and elimination t[1/2] was longer (P = .005) in the elderly, but area under the concentration curve to 12 hr and maximum concentration did not differ by age group. Maximum impairment was greater in the elderly for all assessments. Mean EC50 values differed between the elderly (25.3 and 25.0 ng/ml) and the young (39.8 and 36.5 ng/ml) on card sorting and digit symbol substitution, respectively (P < .001). Bolus treatment data were used to individualize doses for the crossover of placebo and alprazolam; infusions were designed to maintain a plateau alprazolam concentration between 1 and 9 hr. Alprazolam concentrations through 12 hr did not differ between the young and elderly. Median t[1/2] for offset of effect for digit symbol substitution was 2.8 hr in the young and 4.9 hr in the elderly (P = .05). Therefore, aging decreases alprazolam clearance and increases sensitivity to effects of alprazolam through a mechanism other than pharmacokinetics; aging also decreases the rate of offset of effect of alprazolam. In addition, the data provide insight into the intensity of initial effect as a determinant of rate of tolerance development.

Adult↗