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S T Smith

Publications and source records attributed to S T Smith.

At least 19 recordsLinked to original sources
PubMed1995

Skeletal repair by in situ formation of the mineral phase of bone.

A process has been developed for the in situ formation of the mineral phase of bone. Inorganic calcium and phosphate sources are combined to form a paste that is surgically implanted by injection. Under physiological conditions, the material hardens in minutes concurrent with the formation of dahllite. After 12 hours, dahllite formation was nearly complete, and an ultimate compressive strength of 55 megapascals was achieved. The composition and crystal morphology of the dahllite formed are similar to those of bone. Animal studies provide evidence that the material is remodeled in vivo. A novel approach to skeletal repair is being tested in human trials for various applications; in one of the trials the new biomaterial is being percutaneously placed into acute fractures. After hardening, it serves as internal fixation to maintain proper alignment while healing occurs.

Animals↗
PubMed1995

The human ocular torsion position response during yaw angular acceleration.

Recent results by Wearne [(1993) Ph.D. thesis] using the scleral search-coil method of measuring eye position indicate that changes in ocular torsion position (OTP) occur during yaw angular acceleration about an earth vertical axis. The present set of experiments, using an image processing method of eye movement measurement free from the possible confound of search coil slippage, demonstrates the generality and repeatability of this phenomenon and examines its possible causes. The change in torsion position is not a linear vestibulo-ocular reflex (LVOR) response to interaural linear acceleration stimulation of the otoliths, but rather the effect is dependent on the characteristics of the angular acceleration stimulus, commencing at the onset and decaying at the offset of the angular acceleration. In the experiments reported here, the magnitude of the angular acceleration stimulus was varied and the torsion position response showed corresponding variations. We consider that the change in torsion position observed during angular acceleration is most likely to be due to activity of the semicircular canals.

Acceleration↗
PubMed1995

Gender risk for anaphylactoid reaction to radiographic contrast media.

BACKGROUND: Female predominance has been reported previously in series of anaphylaxis cases; however, no definite precedent has been established for greater risk of anaphylactoid reaction caused by contrast media infusion on the basis of gender. OBJECTIVE: This study was designed to determine whether greater risk for anaphylactoid reaction caused by intravenous contrast media infusion exists in association with female gender. METHODS: Rates of anaphylactoid and severe anaphylactoid reaction, according to gender, were determined in a sample of 5264 consecutive patients receiving conventional radiocontrast media during performance of computed tomography. RESULTS: Of 80 adverse reactions caused by contrast media infusion, 73 (1.39%) were classified as anaphylactoid in nature. Among 5191 patients who received intravenous contrast media without experiencing an anaphylactoid reaction, there were 2642 male patients (51%) and 2549 female patients (49%); reactors included 22 male patients and 51 female patients (odds ratio = 2.40, 95% confidence interval = 1.42-4.10, p < 0.0005). Female patients also comprised 21 of 22 cases of severe anaphylactoid reaction (odds ratio = 21.77, 95% confidence interval = 3.13-435.12, p < 0.0005). CONCLUSION: Greater risk for anaphylactoid and severe anaphylactoid reaction exists in association with female gender. Further studies are needed to identify mechanisms that can explain this risk. The importance of these findings for cost-effective use of lower osmolality contrast media need to be determined.

Anaphylaxis↗
PubMed1995

Inserting the Ftz homeodomain into engrailed creates a dominant transcriptional repressor that specifically turns off Ftz target genes in vivo.

The Engrailed homeodomain protein is an 'active' or dominant transcriptional repressor in cultured cells. In contrast, the Fushi Tarazu homeodomain protein is an activator, both in cultured cells and in Drosophila embryos, where it activates several known target genes, including its own gene. This auto-activation has been shown to depend on targeting to a fushi tarazu enhancer by the Fushi Tarazu homeodomain. We combined Fushi Tarazu targeting and Engrailed active repression in a chimeric regulator, EFE. When EFE is ubiquitously expressed, it overrides endogenous Fushi Tarazu and causes a fushi tarazu mutant phenotype. Normal Fushi Tarazu target genes are affected as they are in fushi tarazu mutants. One such target gene is repressed by EFE even where Fushi Tarazu is not expressed, suggesting that the repression is active. This is confirmed by showing that the in vivo activity of EFE depends on a domain that is required for active repression in culture. A derivative that lacks this domain, while it cannot repress the endogenous fushi tarazu gene, can still reduce the activity of the fushi tarazu autoregulatory enhancer, suggesting that it competes with endogenous Fushi Tarazu for binding sites in vivo. However, this passive repression is much less effective than active repression.

Animals↗
PubMed1995

External fixation and limited internal fixation for complex fractures of the tibial plateau.

Twenty-one complex fractures of the tibial plateau in twenty patients were treated with closed reduction, interfragmental screw fixation of the articular fragments, and application of a unilateral half-pin external fixator. The average duration of external fixation was twelve weeks (range, three to twenty weeks). The fixator was left in situ until the fracture had united in all but two patients. All of the fractures healed. The complications with this technique were attributable primarily to the proximal half-pins of the external fixator. Seven patients needed antibiotics for an infection at a pin site, and two had septic arthritis that necessitated arthrotomy and débridement. The average duration of follow-up was thirty-eight months. The range of motion of nineteen of the twenty-one knees was at least a 115-degree arc. Laxity was evident in seven knees, but no patient complained of instability of the knee. Radiographs showed malalignment of more than 6 degrees in three knees compared with the normal, contralateral knee and evidence of post-traumatic osteoarthrosis in five knees. The Iowa knee score, determined for nineteen patients, averaged 87 points (range, 55 to 100 points). The SF-36 general health survey demonstrated that most patients had function close to that of age-matched controls. We concluded that external fixation with limited internal fixation is a satisfactory technique for the treatment of selected complex fractures of the tibial plateau.

Adult↗
PubMed1993

Elevated risk of anaphylactoid reaction from radiographic contrast media is associated with both beta-blocker exposure and cardiovascular disorders.

BACKGROUND: A case-control study, with both retrospective and concurrent subject selection, was performed (1) to determine whether greater risk for anaphylactoid reaction from contrast media associated with beta-blocker exposure reflects presence, or is independent of underlying cardiovascular disorder; and (2) to characterize further the risk of anaphylactoid reaction from contrast media in patients with cardiovascular disorders and patients with asthma. METHODS: Adverse reactions from intravenous contrast media were recorded in accordance with quality assurance guidelines. Anaphylactoid reactions were classified as mild to moderate (urticaria/angioedema), severe (stridor, bronchospasm, or hypotension), or major and life-threatening (hypotension with or without the need for subsequent hospitalization). Medical records from reactors were compared with those from matched (gender, age, date, and type of contrast study) controls who received conventional contrast media without adverse reaction. RESULTS: Of 34,371 intravenous contrast media procedures performed, 122 anaphylactoid reactions were recorded. The risk of anaphylactoid reaction was significantly associated with asthma (odds ratio [OR], 8.74; 95% confidence interval [CI], 2.36 to 32.35; P = .0012). The risk of bronchospasm was associated with beta-blocker exposure (OR, 3.73; 95% CI, 1.18 to 11.75; P = .025) and with asthma (OR, 16.39; 95% CI, 4.30 to 62.46; P = .0001). The risk of major and life-threatening reaction was associated with the presence of cardiovascular disorder (OR, 7.71; 95% CI, 1.04 to 57.23; P = .046). Among patients with severe reactions, the risk of hospitalization was elevated by the presence of cardiovascular disorder (P = .001), exposure to beta-blockers (OR, 7.67; 95% CI, 1.79 to 32.85; P = .029), or asthma (OR, 20.7; 95% CI, 1.21 to 355.55; P = .065). Although beta-blocker exposure and the presence of cardiovascular disorder were highly associated (chi 2 = 49, P < .001), a greater risk of bronchospasm with severe reaction was observed in nonasthmatic patients with cardiovascular disorders receiving beta-blockers (OR, 15.75; P = .023). Among reactors with asthma, receiving beta-blockers, or with a cardiovascular disorder, 60.8% (31/51) experienced severe anaphylactoid reactions, compared with 35.2% (25/71) of patients without these risk factors (OR, 3.62; P = .005). CONCLUSIONS: beta-Blocker exposure and cardiovascular disorder are both statistically significant risk factors for severe anaphylactoid reaction from contrast media. Thus, patients receiving beta-adrenergic blockers and patients with asthma, on the basis of greater risk for bronchospasm, and patients with cardiovascular disorders, on the basis of elevated risk of major and life-threatening reaction, are appropriate target populations for risk reduction measures before receiving intravenous infusion of contrast media.

Adrenergic beta-Antagonists↗
PubMed1992

Evaluation of pretreatment transvaginal ultrasonography in the management of patients with endometrial carcinoma.

OBJECTIVE: The objective of this study was to evaluate the usefulness of pretreatment assessment with ultrasonography in patients with endometrial carcinoma. STUDY DESIGN: Fifty patients with endometrial carcinoma diagnosed by endometrial biopsy or curettage were studied before hysterectomy, bilateral salpingo-oophorectomy, and selected lymph node sampling. Ultrasonographic criteria for determination of tumor grade, depth of myometrial invasion, uterine volume, and tumor volume were established. Tumor grade was compared with preoperative and postoperative pathologic diagnoses, depth of invasion was compared with postoperative pathologic evaluation, and uterine volume and tumor volume were compared with postoperative evaluation of tumor grade and depth of invasion. Data were analyzed by chi 2 testing, and, where appropriate, sensitivity, specificity, and accuracy of the ultrasonographic measurements were determined. RESULTS: The following statistically significant correlations (p less than or equal to 0.05) were found. Ultrasonography predicted tumor grade as accurately as preoperative pathologic evaluation did. Depth of invasion less than or equal to 50% or greater than 50% significantly correlated. Uterine volume less than or equal to 200 ml predicted less than or equal to 50% depth of invasion 28 of 32 times. Uterine volume greater than 500 ml was noted in six cases; five of these had grade 2 or 3 tumor and four had depth of invasion greater than 50%. Tumor volume less than or equal to 20 ml predicted a grade 1 tumor in 25 of 39 cases and depth of invasion less than or equal to 50% in 34 of 39 cases. Tumor volume greater than 20 ml correlated with a grade 2 or 3 tumor in 11 of 11 cases and a depth of invasion greater than 50% in seven of 11 cases. In 25 grade 1 tumors diagnosed postoperatively by pathologic study, none was associated with a tumor volume greater than 20 ml. CONCLUSION: Pretreatment ultrasonographic measurements should be of value in the management of patients with endometrial carcinoma.

Adult↗
PubMed1992

The treatment of pelvic soft tissue radiation necrosis with hyperbaric oxygen.

OBJECTIVE: The purpose of this study was to examine the therapeutic effects of hyperbaric oxygen on radiation-induced soft tissue necrosis in patients who previously received treatment for a gynecologic malignancy. STUDY DESIGN: Fourteen patients whose necrotic wounds failed to heal after 3 months of conservative therapy were enrolled in a prospective observational study. Outcome of hyperbaric oxygen treatment was measured by resolution of necrosis. RESULTS: Fourteen patients underwent 15 courses of hyperbaric oxygen treatments. All those with radiation necrosis of the vagina alone or in association with rectovaginal fistula had complete resolution of necrosis with hyperbaric oxygen. Only one treatment failure occurred. CONCLUSION: Hyperbaric oxygen is a safe, effective, and well-tolerated treatment for radiation-induced soft tissue necrosis.

Adult↗
PubMed1991

Increased risk for anaphylactoid reaction from contrast media in patients on beta-adrenergic blockers or with asthma.

OBJECTIVE: To determine whether greater risk for anaphylactoid reaction from intravenous urographic contrast media exists in patients receiving beta-adrenergic blockers or in asthmatic patients. DESIGN: Case-control study. SETTING: Tertiary care, referral-based medical center. PATIENTS: Of 28,978 intravenous urographic contrast media procedures done from July 1987 to June 1988, 49 patients experienced moderate to severe anaphylactoid reaction. Medical records from these 49 reactors were compared with those from a control group matched for gender, age, and date and type of contrast study who received intravenous urographic contrast media without adverse reaction. MAIN RESULTS: Patients exposed to beta-adrenergic blockers or with asthma comprised 39% (19 of 49) of reactors, compared to 16% (13 of 83) of matched controls (odds ratio, 3.43; 95% CI, 1.45 to 8.15; P = 0.005). Exposure to beta-blockers was 27% among reactors and 12% in matched controls (odds ratio, 2.67; CI, 1.01 to 7.05; P = 0.036). Asthma was found in 12% of reactors and 4% of controls; after correction for beta-blocker use, asthma was also associated with increased risk for anaphylactoid reaction (odds ratio, 4.54; CI, 1.03 to 20.05; P = 0.046). Compared with nonasthmatic patients not taking beta-blockers, asthmatic patients were at greater risk for anaphylactoid reaction with bronchospasm (P = 0.02). Five of 13 reactors receiving beta-blockers became hypotensive, and three needed hospitalization. Compared with nonasthmatic patients not taking beta-blockers, patients exposed to beta-blocking drugs were almost nine times (odds ratio, 8.7; CI, 0.81 to 93.5; P = 0.075) more likely to be hospitalized after an anaphylactoid reaction. CONCLUSION: Increased risk for moderate to severe anaphylactoid reaction from intravenous urographic contrast media exists in patients receiving beta-adrenergic blockers or with asthma. These patients are appropriate target populations for efforts to reduce risk before intravenous urographic contrast media are administered.

Adrenergic beta-Antagonists↗
PubMed1991

Transthoracic and transesophageal echocardiography in the diagnosis and surgical management of right atrial myxoma.

An asymptomatic patient was discovered to have a large right atrial myxoma by transthoracic echocardiography. Preoperative considerations included the possibility of satellite lesions, left atrial origin, and a question of tricuspid valve involvement. Subsequent operative transesophageal echocardiography demonstrated single-stalk attachment in the right atrial septal wall and no satellite lesions. Doppler and color flow examination immediately following tumor removal aided in the decision not to perform tricuspid annuloplasty as there was no significant tricuspid regurgitation. The combined use of transthoracic and transesophageal echocardiography with Doppler and color flow imaging aids in the preoperative and intraoperative diagnosis and surgical management of right atrial tumors.

Echocardiography↗
PubMed1988

Serial evaluation of left ventricular function in congestive heart failure by measurement of peak aortic blood acceleration.

Peak acceleration of blood in the ascending aorta, an index of global systolic left ventricular (LV) function, can be measured noninvasively using a continuous wave Doppler velocimeter applied suprasternally. The feasibility of this approach as a tool for detecting improvement of LV function was studied in 16 patients with congestive heart failure (CHF). Measurements were made daily for 6 consecutive days. The daily variability of peak acceleration examined in 11 normal subjects was +/- 2 m/s/s. In 11 of 16 patients with CHF, peak acceleration increased more than 2 m/s/s by day 6 compared with day 1 (group 1). In 5 of 16 patients, peak acceleration remained unchanged (group 2). In group 1, peak acceleration was 11 +/- 1 m/s/s on day 1 and increased to 16 +/- 1 m/s/s on day 6 (p less than 0.001). In this group, CHF resolved by day 6 in 9 of 11 patients. In group 2, peak acceleration was 9 +/- 1 m/s/s on day 1 and remained unchanged through day 6. In these 5 patients, the signs and symptoms of CHF persisted through day 6. The results suggest that peak acceleration measured noninvasively with continuous wave Doppler can detect improvement of LV function in patients with CHF. The approach provides a simple and reliable bedside means for serial evaluation of LV systolic function.

Adult↗
PubMed1988

Collagen/hydroxylapatite implant for augmenting deficient alveolar ridges: twelve-month clinical data.

In a multicenter study, 77 edentulous patients had mandibular augmentation with implants of purified fibrillar collagen combined with dense hydroxylapatite (Alveoform Biograft); 22 of these patients also had maxillary augmentation. Most patients had Class III or IV mandibular atrophy, and had outpatient surgery with the subperiosteal tunneling technique. Temporary splints were worn for 24 hours post-surgery. Mean ridge height was 15.3 mm before surgery and 19.5 mm after 12 months, an augmentation of 4.2 mm. Predictable compaction occurred largely in the first few months after denture loading. Most patients, surgeons, and prosthodontists assessed the results of the procedure as good to excellent at 1 year following implantation. Adverse experiences, largely dehiscence and paresthesia, tended to resolve over time. Sera from ten patients demonstrated antibodies to bovine collagen that were not clinically significant. Alveolar augmentation with collagen/hydroxylapatite achieved clinically significant results that compared favorably with those achieved with other types of ceramic implants.

Adult↗
PubMed1988

Enhanced survival of gamma-irradiated Escherichia coli following pretreatment with dithiothreitol.

Survival of three strains of Escherichia coli K12 was studied with respect to radiation protection by dithiothreitol (DTT). The three strains compared were AB2462 recA, AB2470 rec21 and their DNA repair-competent prototype, AB1157. The strains were incubated in 10 mmol dm-3 DTT for 60 min and allowed an expression period for SOS functions to appear which may have been induced by DTT. Following the expression period the DTT-incubated cells and incubated control cells were irradiated. When AB1157 cells were pretreated with chloramphenicol (200 micrograms cm-3) for a period of 30 min prior to addition of the induction media no increase in survival was seen. When catalase (0.1 mg cm-3) was added to the AB1157 cells prior to the induction media a decrease in the degree of induction was noted with an enhancement ratio (ER) of 0.893 (ER-1 = 1.12). Furthermore, DTT-treated AB2462 and AB2470 demonstrated no increase in survival when compared to control cells. In radiation experiments on either strain of E. coli with or without DTT present during irradiation, the following were observed: (1) survival of AB1157 was enhanced with a dose modification factor (DMF) of 1.7 with DTT present and 1.3 with pretreatment; (2) the rec mutants showed no change in survival at any dose with a DMF of approximately 1.0. Results indicate that, using our protocol, inducible repair is of more importance than free radical scavenging by DTT. Furthermore, DTT-treated AB2462 demonstrated no increase in survival when compared to control cells. In radiation experiments on either strain of E. coli with and without DTT present during irradiation, the following were observed: (1) survival of AB1157 was enhanced with a DMF of 1.7 with DTT present during irradiation and 1.3 with only pretreatment; (2) the recA and recB mutants showed no change in cell survival at any dose with a DMF of approximately 1.0. Results indicate that, using our pretreatment protocol, inducible repair is of more importance in protection than free radical scavenging by DTT.

Catalase↗
PubMed1988

Absence of pyrimidine salvage and prevention of thymineless radiosensitization in Escherichia coli thyA cells fed dihydrothymine or thymine glycol.

Little information is available concerning the metabolic fate of radiation-induced thymine base damage products once they have been excised from DNA. The present study was an attempt to determine whether or not thymine-requiring mutants of Escherichia coli could grow on dihydrothymine (DHT) and thymine glycol (TG) by "salvaging" the altered thymines. A second test of thymine product utilization was prevention of thymineless radiosensitization. Results showed that very low growth of Thy- cells on DHT or TG could be explained by the presence of less than or equal to 1% contaminating thymine in the mixtures. Radiation dose-modification factors (DMFs) for thyA cells fed DHT or TG for 3 h were 1.38 +/- 0.28 and 1.26 +/- 0.24, respectively, whereas the DMF for 3 h thymine-starved cells was 1.63 +/- 0.05. The small (approximately 25%) amelioration of thymineless radiosensitization observed in DHT- or TG-fed cells could probably be explained by contaminating thymine in the medium. Although DHT is a normal metabolite in some cells, neither DHT nor TG could be used efficiently by thymine-requiring cells in the protocol presented.

Dose-Response Relationship, Radiation↗
PubMed1987

Rate and extent of recovery of left ventricular function in patients following acute myocardial infarction.

To determine the rate and extent of recovery of left ventricular (LV) performance following acute myocardial infarction (MI), peak aortic blood acceleration was measured serially in 26 patients and in 11 normal volunteers with a continuous wave Doppler placed suprasternally. In patients, Doppler measurements were made 20 +/- 2 hours after the acute onset of chest discomfort and were repeated daily for 6 consecutive days. Infarction patients were divided into two groups. Group I consisted of 15 patients who did not have a previous MI and whose present course was not complicated by congestive heart failure (CHF). Group II consisted of 11 patients who had either a previous MI or developed CHF during the present admission. Peak acceleration in the normal volunteers showed minimal daily variations over a period of 6 days. Peak acceleration in the entire group of 26 MI patients increased from 13 +/- 3 m/sec/sec on the day of admission (day 1) to 18 +/- 6 m/sec/sec on day 6 (p less than 0.001). In group I, peak acceleration increased from 13 +/- 4 to 20 +/- 6 m/sec/sec between day 1 and day 6 (p less than 0.001). In group II, however, peak acceleration was 12 +/- 2 m/sec/sec on day 1 and increased to only 15 +/- 4 m/sec/sec on day 6 (NS). These results indicate that LV performance, based upon peak acceleration of blood in the ascending aorta, improves markedly within 6 days in patients suffering their first MI uncomplicated by CHF.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Evaluation of collagen/hydroxylapatite for augmenting deficient alveolar ridges: a preliminary report.

A multicenter study was undertaken to evaluate a new alveolar ridge augmentation material composed of purified fibrillar collagen and particulate hydroxylapatite (PFC/HA). In a study of 77 patients and 99 reconstructed ridges, this material provided superior handling properties over HA alone as evidenced by its ease of surgical placement and manipulation, and the rarity of particle migration or displacement. Moreover, the rapid development of ridge firmness and stability allowed for the loading of dentures within three to six weeks. Prosthodontist evaluations and surveys of patient satisfaction showed great satisfaction with denture fit, comfort, esthetics, speech, and ability to masticate.

Adult↗