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Biomedical subjects

D C Smith

Publications and source records attributed to D C Smith.

At least 253 records · Page 14Linked to original sources
PubMed1987

Reinnervation of the dentate gyrus and recovery of alternation behavior following entorhinal cortex lesions.

Adult male rats were implanted with chronically indwelling recording electrodes in the dentate hilus of one hemisphere and bipolar stimulating electrodes in the contralateral entorhinal cortex (EC). Daily measurements were then made of the amplitude of responses, evoked through the crossed temporodentate (CTD) pathway, while the rats were unanesthetized and unrestrained. The implanted rats were also trained to alternate turns in a T-maze, with the use of a rewarded-alternation procedure. After reaching criterion performance in the alternation task, each rat was given a lesion of the EC ipsilateral to the recording electrode (n = 14) or a sham lesion (n = 5). Mean amplitudes of the evoked responses increased over Postlesion Days 4-11, probably due to reactive synaptogenesis in the CTD system, reaching a level that was significantly elevated above prelesion levels by Postlesion Day 6. Rats given EC lesions exhibited a transient impairment in alternation performance, with the mean alternation score significantly below prelesion levels on Postlesion Days 2-6. Although 2 EC-lesioned rats did not show a behavioral deficit, the electrophysiological increases and behavioral recovery were correlated in the remaining 12 cases (Pearson r = .73). These results are consistent with the interpretation that sprouting by the CTD system contributes to recovery of T-maze alternation performance following unilateral EC lesions.

Animals↗
PubMed1987

Stability of oestrogen receptor status in sequential biopsies from patients with breast cancer.

Sequential biopsies of breast cancer tissue were obtained from a total of 210 women in order to assess any change in oestrogen receptor (ER) status arising spontaneously or as a result of intervening therapy. A combined assay measuring both cytosol and nuclear oestrogen receptors was used for all samples. One hundred and fifty-five patients had biopsies of their primary tumour and of a later loco-regional recurrence; 26 had biopsies of their primary tumour and a recurrence or new primary in the opposite breast; and 29 had sequential biopsies of recurrent disease only. Overall only 61.2% of the primary tumours retained their original status with respect to both cytosol and nuclear oestrogen receptors on recurrence. These results were influenced by intervening therapy, however, and if only untreated patients are considered, over 70% of their recurrences contain the same combination of cytosol and nuclear receptors as found in the primary tumours. For tumours 'recurring' in the opposite breast, the pattern was similar with 69.2% retaining the same status as the first primary. The agent found most likely to alter I:R status was tamoxifen and in the samples taken from patients undergoing treatment with this drug, no tumour was found to contain measurable receptor.

Biopsy↗
PubMed1987

Operative balloon angioplasty in the treatment of internal carotid artery fibromuscular dysplasia.

Seven patients with symptomatic fibromuscular dysplasia have had eight internal carotid arteries treated by operative balloon dilatation. This technique is described in detail and provides three distinct advantages over conventional graduated intraluminal dilatation--atraumatic passage of the catheter through the affected vessel with fluoroscopic guidance; precise dilatation of the involved segment of the internal carotid artery; and the application of a radial force against the arterial wall rather than a longitudinal shear force, thereby making intimal damage less likely. There were no treatment complications in this group of patients. This technique of balloon angioplasty is compared with the results of treatment in eight patients with fibromuscular dysplasia of the internal carotid artery, who had percutaneous transfemoral angioplasty. Long-term follow-up revealed the resolution of symptoms in all patients.

Aged↗
PubMed1987

Angiographic preoperative bowel segment localization using methylene blue, isosulfan blue, and fluorescein.

A canine model was used to determine the feasibility of preoperative, angiographic staining of bowel segments. Because methylene blue (MB) is contraindicated in patients with glucose-6-phosphate dehydrogenase deficiency or unstable hemoglobins, two alternate dyes, isosulfan blue (lymphazurin) and fluorescein were also studied. These three dyes were injected into 27 different mesenteric arterial branches in seven dogs following transfemoral catheterization. The duration of staining was evaluated over periods ranging from hours to 14 days, and pathologic sections were obtained to detect possible toxic effects. MB staining adequate for surgical resection persisted consistently up to 6 hours. Isosulfan blue and fluorescein produced adequate staining for only 30 to 60 minutes. Toxic mucosal changes were noted in four of 12 segments harvested within hours of the injection of MB and in none of the five MB injected segments harvested at four of 14 days. These changes varied greatly from focal regions of superficial necrosis to more generalized regions of transmucosal necrosis. All of the segments injected with isosulfan blue or fluorescein were free of histologic damage. It is concluded that the duration of staining produced by MB is sufficiently long to allow injection at angiography rather than at surgery. This allows decreased catheter time, and more importantly, precludes the possibility of interval catheter displacement. However, its clinical use should be viewed with some caution until its safety is established by further investigation. Isosulfan blue and fluorescein appear as alternate injectables, particularly for patients in whom MB is contraindicated. Because of their relatively short staining durations, injections with these agents should be made during surgery after angiographic catheter placement, although this method risks interval catheter dislodgement.

Angiography↗
PubMed1987

The influence of premedication on the occurrence of dysrhythmias during oral surgery.

The incidence of cardiac dysrhythmia during inpatient dental anaesthesia with enflurane was studied following either hyoscine or droperidol as a supplement to papaveretum premedication. None of the subgroup given droperidol exhibited dysrhythmias, compared to 4.4% of those patients given hyoscine. This difference was not significant at the 5% level (0.2 greater than p greater than 0.1).

Adolescent↗
PubMed1987

Pulmonary arteriography: comparison of cough stimulation effects of diatrizoate and ioxaglate.

Twenty-five patients were observed in a prospective crossover study to determine whether the new low-osmolality contrast agents would be less prone than conventional agents to produce coughing during pulmonary arteriography. Selective left and right pulmonary arteriography (two views of each side) was performed with alternating administrations of diatrizoate sodium meglumine and ioxaglate sodium meglumine. Twenty-one patients had all four injections while four patients received injections on only one side. Sixteen of 25 patients coughed on at least one injection of diatrizoate, with three of these experiencing explosive coughing. One of 25 patients coughed with ioxaglate, and that was only minimally. This difference is statistically significant (P less than .001, on the basis of McNemar chi 2 test for paired data). When no coughing occurred, the quality of the diatrizoate and ioxaglate radiographs was indistinguishable. We conclude that ioxaglate is useful in pulmonary arteriography because of its lack of cough stimulation.

Adult↗
PubMed1987

Development and implementation of a quality assurance program for mammography.

As a pilot study for a national campaign to promote the use of screening mammography, the Virginia Division of the American Cancer Society conducted a breast cancer awareness project with mammography screening. An important part of the program was the development of a quality assurance program for mammography. Guidelines were established for equipment, image recorders, processing, dose, and patient positioning. A survey of information about the mammographic equipment was conducted, and the mammograms from each facility were reviewed. A total of 63 mammographic units in 56 facilities statewide were included in the month-long program during which approximately 9,000 women were screened.

Breast Neoplasms↗
PubMed1987

Traumatic rupture of the thoracic aorta. A review of 49 cases.

We examined retrospectively the chest radiograph of forty nine patients with angiographically proven aortic ruptures. The plain film findings found most consistently were a wide mediastinum (69.5%), partial obliteration of the descending aorta (67.3%), left apical cap (65.3%), downward displacement of the left main bronchus (65.3%), tracheal deviation to the right (63.2%), obscuration of the aortic arch (55.1%), right paratracheal stripe thickening (53%) and nasogastric tube deviation to the right (50%). We also examined 113 sequential aortograms performed after thoracic trauma over 3 years, to determine the positive rate in our series; 14 studies were positive for a rate of 12.4%. No single case of proved ruptured aorta with a normal chest radiograph was detected.

Aorta, Thoracic↗
PubMed1986

Psychological impact of adjuvant chemotherapy in the first two years after mastectomy.

Psychological symptoms were assessed over two years in a randomised trial of three forms of treatment given to women after mastectomy for stage II breast cancer. The treatments were: three weeks' radiotherapy; one year's adjuvant chemotherapy with cyclophosphamide, methotrexate, and 5-fluorouracil; and radiotherapy followed by chemotherapy. Analysis of the results on an intention to treat basis showed no substantial differences in depression or anxiety among groups at one, three, or six months after the operation. At 13 months, however, patients who had been allocated chemotherapy had significantly more symptoms, especially depression, than control patients treated with radiotherapy alone. Conditioned reflex nausea and vomiting increased considerably during the second six months of chemotherapy and persisted for up to a year afterwards. The psychological morbidity of adjuvant chemotherapy could be substantially reduced if courses of treatment were restricted to about six months.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1986

Adjuvant radiotherapy and chemotherapy in breast cancer.

Three hundred and twenty-two women with involvement of axillary lymph nodes following surgery for operable breast cancer were randomized to receive either postoperative radiotherapy, chemotherapy (CMF) or radiotherapy followed by chemotherapy. There was an increase in disease free interval in pre- and postmenopausal patients receiving radiotherapy and chemotherapy regardless of the number of nodes involved. However, there was a trend towards an improvement in disease related survival only in those patients with more than three nodes involved.

Aged↗
PubMed1986

Crystal growth on the outer enamel surface--an alternative to acid etching.

Over the past 2 years an increasing concern has developed about the possible iatrogenic effects of phosphoric acid-etch bonding techniques on the enamel surface. There is an evident need to develop a mechanical or chemical retention system that would not alter (or would minimally alter) the outer enamel surface. An alternative to the conventional phosphoric acid etch technique has been developed. A preliminary clinical trial showed promising performance under normal clinical conditions. These results were achieved with a minimal loss of surface enamel as evidenced by scanning electron microscopy. Debonding and cleanup were greatly facilitated. Creating a micromechanical retentive surface by the formation of a crystalline interface is a potential alternative to phosphoric acid etching.

Acid Etching, Dental↗
PubMed1986

Biodegradation of the orthodontic bracket system.

Corrosion of the orthodontic appliance may occur in vivo with time. Electrochemical breakdown of corrosion-resistant high nickel and titanium wire can also occur. The use of recycled brackets could possibly accelerate the corrosion process. New and recycled brackets were evaluated in vitro in an artificial saliva system. The results indicated that different brands of new brackets have differences in corrosion behavior. In addition, recycling by the three commercial processes tested increased the liability of brackets to undergo corrosion. Superior behavior was noted for two types of bracket bases. Bracket corrosion may be assessed by a simple in vitro test.

Biodegradation, Environmental↗