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Biomedical subjects

A D Smith

Publications and source records attributed to A D Smith.

At least 127 records · Page 7Linked to original sources
PubMed1998

Evaluation of problem solving and communication skills of persons with schizophrenia.

Although much research has shown positive outcomes of teaching problem solving and communication skills to persons with schizophrenia, the amount of research on the assessment of these two sets of skills has been modest. The current study demonstrates an effective model for their assessment and includes a previously neglected procedure to determine if subjects attended to the skill prompts. It replicates and expands prior findings on problem solving and communication skills. Results indicated that persons with schizophrenia were generally deficit in problem solving skills. Persons without schizophrenia seemed to use more behavioral information when deciding if a problem existed and they were better able to differentiate between appropriate and inappropriate solutions to problems. Persons with schizophrenia were found to be deficit in communication skills that facilitate interaction and showed a style that subordinated their wants to those of others.

Adult↗
PubMed1998

An electrostrictive drive for fine pitch control in double-crystal monochromators.

Precise control of the pitch angle of the crystals in a double-crystal monochromator is essential to preserve their accurate alignment while the instrument is scanned. Computer-controlled piezoceramic electrostrictive actuators have recently been installed to the top crystal in two monochromators at the Daresbury SRS to facilitate this. This complements the coarser control provided by the existing stepper motor to give an accurate positioning of the crystal alignment over the full rocking-curve width of the crystals. To maintain accurate alignment during a scan, a number of servo feedback options have been devised. In this paper an analysis of the performance of these drives is presented and their utility in a variety of different experimental techniques is discussed.

Journal Article↗
PubMed1998

Development of X-ray photoemission electron microscopy (X-PEEM) at the SRS.

The use of synchrotron radiation sources for X-ray spectroscopy is a well known and developed field. The majority of applications, however, have been limited to studies of materials containing only a single phase of the element of interest. Owing to limited availability of suitable instrumentation, the study of materials comprising intergrowths of different phases has presented difficulties in analysis. The majority of natural materials, including mineralogical samples, fall into this category. However, by applying the technique of photoemission electron microscopy (PEEM) to view the X-ray stimulated photoemission generated at an absorption edge, micro-area-selectable spectroscopy becomes possible. An instrument for X-ray PEEM (X-PEEM) is being developed at the Daresbury SRS and this paper shows how it can be used to obtain characteristic L-edge XANES spectra from finely intergrown iron oxide minerals.

Journal Article↗
PubMed1998

Use of YB(66) as monochromator crystals for soft-energy EXAFS.

YB(66)(400) crystals present a new advance in monochromator crystals suitable for use at energies below 2 keV. In this paper a comparison of their performance with that provided by the more usual beryl and quartz crystals, which cover the same energy range, is presented. In general, the YB(66) crystals are much superior; however, they do exhibit a pair of large 'crystal glitch'-type features in the 1380-1440 eV region. These fall in the Mg K-EXAFS region and so can present a serious problem in studies of this edge for a wide range of materials. An important class of materials so afflicted are magnesium-substituted aluminophosphate molecular sieves (zeolites), which are used in many applications, in particular as solid acid catalysts for conversion of methanol to hydrocarbon.

Journal Article↗
PubMed1998

Folate, vitamin B12, and serum total homocysteine levels in confirmed Alzheimer disease.

BACKGROUND: Recent studies suggest that vascular disease may contribute to the cause of Alzheimer disease (AD). Since elevated plasma total homocysteine (tHcy) level is a risk factor for vascular disease, it may also be relevant to AD. OBJECTIVE: To examine the association of AD with blood levels of tHcy, and its biological determinants folate and vitamin B12. DESIGN: Case-control study of 164 patients, aged 55 years or older, with a clinical diagnosis of dementia of Alzheimer type (DAT), including 76 patients with histologically confirmed AD and 108 control subjects. SETTING: Referral population to a hospital clinic between July 1988 and April 1996. MAIN OUTCOME MEASURES: Serum tHcy, folate, and vitamin B12 levels in patients and controls at entry; the odds ratio of DAT or confirmed AD with elevated tHcy or low vitamin levels; and the rate of disease progression in relation to tHcy levels at entry. RESULTS: Serum tHcy levels were significantly higher and serum folate and vitamin B12 levels were lower in patients with DAT and patients with histologically confirmed AD than in controls. The odds ratio of confirmed AD associated with a tHcy level in the top third (> or = 14 micromol/L) compared with the bottom third (< or = 11 micromol/L) of the control distribution was 4.5 (95% confidence interval, 2.2-9.2), after adjustment for age, sex, social class, cigarette smoking, and apolipoprotein E epsilon4. The corresponding odds ratio for the lower third compared with the upper third of serum folate distribution was 3.3 (95% confidence interval, 1.8-6.3) and of vitamin B12 distribution was 4.3 (95% confidence interval, 2.1-8.8). The mean tHcy levels were unaltered by duration of symptoms before enrollment and were stable for several years afterward. In a 3-year follow-up of patients with DAT, radiological evidence of disease progression was greater among those with higher tHcy levels at entry. CONCLUSIONS: Low blood levels of folate and vitamin B12, and elevated tHcy levels were associated with AD. The stability of tHcy levels over time and lack of relationship with duration of symptoms argue against these findings being a consequence of disease and warrant further studies to assess the clinical relevance of these associations for AD.

Aged↗
PubMed1998

Levels and proteolytic processing of chromogranin A and B and secretogranin II in cerebrospinal fluid in neurological diseases.

Human cerebrospinal fluid (CSF) contains chromogranin A and B and secretogranin II which represent peptides secreted from neuronal large dense core vesicles. Within these vesicles these precursor peptides are at least partly processed to smaller peptides. We analysed the CSF levels of chromogranins/secretogranin by radioimmunoassay using specific antisera. The degree of their processing was characterized by molecular sieve column chromatography followed by radioimmunoassay. As previously shown secretogranin II is fully processed to smaller peptides including the peptide secretoneurin, whereas processing of chromogranin A was more limited. For chromogranin B we found in this study a high degree of processing comparable to that of secretogranin II. An analysis of CSF from patients with multiple sclerosis, essential tremor, Alzheimer and Parkinson disease, did not reveal any differences in proteolytic processing of chromogranins/secretogranin when compared to control CSF. We conclude that in the four diseases investigated there is no change in the proteolytic processing of the chromogranins/secretogranin within the large dense core vesicles. The absolute levels of chromogranins/secretogranin varied in CSF collected in different hospitals, however their relative ratios were remarkable constant. We suggest to use this ratio as a parameter to standardise CSF levels of other peptides, e.g. neuropeptides. In Parkinson patients the chromogranin A/secretogranin II ratio was significantly increased whereas in Alzheimer patients and those with essential tremor and multiple sclerosis no change of the ratios was observed. Apparently there are only limited changes in the biosynthesis, processing, secretion and CSF clearance of these peptides in pathological conditions.

Adult↗
PubMed1998

A prospective endoscopic study of scalloped folds and grooves in the mucosa of the duodenum as signs of villous atrophy.

BACKGROUND: Scalloping of the valvulae conniventes visible at endoscopy may predict the presence of villous atrophy. This prospective study was designed to discover how commonly duodenal mucosal scallops and grooves occurred and to delineate their relationship to villous atrophy. METHODS: All patients undergoing upper gastrointestinal endoscopy by a single observer over 5 years were included. After inspection of the duodenal mucosa, biopsy samples were taken from those in whom the mucosa was abnormal (n = 26) and from those in whom it was not, but where biopsy was indicated (n = 100). RESULTS: None of the 100 endoscopically normal controls had subtotal villous atrophy: 94 had normal histology, 2 had non-atrophic change, and 4 had partial villous atrophy; 14 of the 26 individuals (54%) with abnormal duodena had subtotal villous atrophy, 7 having both scallops and grooves. Four had scallops alone, and three had grooves only. All patients with both scallops and grooves had subtotal villous atrophy (100%), the positive predictive value of which was 36% for scallops alone and 38% for grooves alone. CONCLUSIONS: Scallops and grooves together indicate that subtotal villous atrophy is very likely histologically, even when that diagnosis has not been suspected. A normal duodenum excludes it.

Adult↗
PubMed1998

Endopyelotomy after failed pyeloplasty: the long-term results.

PURPOSE: Endopyelotomy has been proposed as a technique to treat ureteropelvic junction obstruction after failed open pyeloplasty. However, to our knowledge no long-term results of this treatment have been reported. We report the long-term followup of a cohort of patients in whom pyeloplasty failed and who subsequently were treated with endopyelotomy. MATERIALS AND METHODS: From January 1985 to February 1996, 72 patients in whom open surgical pyeloplasty failed were treated with percutaneous endopyelotomy. Mean patient age was 35 years (range 5 to 82). The interval between pyeloplasty and subsequent failure ranged from 2 months to 30 years (mean 57 months). The major presenting symptoms were pain in 82% of cases, fever and urinary tract infections in 37.5%, stone formation in 25% and gross hematuria in 21%. RESULTS: Antegrade endopyelotomy using a hooked knife was performed in all patients with no unusual difficulty and minimal complications. A total of 63 patients (87.5%) had long lasting clinical and radiographic treatment success after a mean followup of 88.5 months. Of the 9 endopyelotomy failures (12.5%) 7 (77.8%) were detected immediately after stent removal at 6 weeks, 1 (11.1%) at 6 months and 1 (11.1%) at 10 months postoperatively (mean failure interval 3.3 months). The failures were corrected with repeat endopyelotomy in 1 patient, pyeloplasty in 3, ileal interposition in 1 and nephrectomy in 4. CONCLUSIONS: Endopyelotomy is the treatment of choice for recurrent ureteropelvic junction obstruction after failed pyeloplasty, with a high and sustained long-term success rate and no reported new failures after 1-year followup. Furthermore, endopyelotomy is technically easier with less morbidity than repeat open pyeloplasty.

Adolescent↗
PubMed1998

Endopyelotomy for horseshoe and ectopic kidneys.

PURPOSE: We report our experience with endopyelotomy for horseshoe and ectopic kidneys in the largest series to date to our knowledge, and discuss the technical modifications adopted to perform successfully percutaneous antegrade endopyelotomy. MATERIALS AND METHODS: From September 1987 to April 1996, 4 patients with horseshoe and 5 with ectopic kidney underwent percutaneous antegrade endopyelotomy for symptomatic ureteropelvic junction obstruction. The percutaneous puncture was made more posteromedial and the ureteropelvic junction was incised lateral. A retrograde percutaneous access tract was created under laparoscopic guidance in pelvic kidneys. RESULTS: The operative procedure was performed uneventfully in all patients with no major bleeding, pleural effusion or visceral perforation. The stents were removed at 6 weeks, and an excretory urogram was performed at 2 weeks, 6 months and yearly thereafter. In 2 patients (22%) with severe hydronephrosis, poor renal function and a long ureteral stricture surgical treatment failed immediately. The remaining 7 patients (78%) had long lasting clinical and radiographic success with a mean followup of 62 months. CONCLUSIONS: Percutaneous antegrade endopyelotomy, with a few technical modifications, is a safe and effective treatment for ureteropelvic junction obstruction associated with horseshoe and ectopic kidneys.

Adult↗
PubMed1998

Transurethral microwave thermotherapy for management of benign prostatic hyperplasia: a single-institution experience.

OBJECTIVES: This is the first and largest single institution retrospective study in the United States to examine the effects of transurethral microwave thermotherapy (TUMT) for the treatment of benign prostatic hyperplasia (BPH). METHODS: From September 1996 to June 1997, 78 men with moderate to severe symptomatic BPH were treated with the Prostatron at our institution. Patient age ranged from 52 to 85 years. Prostate volume ranged from 23 to 110 cc, and mean total energy applied during the treatment was 156.17 kJ. Patients were re-evaluated at 3 months and were asked to answer a questionnaire regarding their opinion about the treatment. RESULTS: At 3 months there was a significant decrease in mean symptom score from 19.6 to 11.2 (P <0.0001). Mean peak flow rate increased from 8.5 to 12.8 mLs (P <0.0001). Mean postvoid residual urine decreased from 56.8 to 22.0 mL (P <0.0001). We did not observe any severe complications. Unlike prior studies, we removed the Foley catheter, and patients performed clean intermittent catheterization (CIC) when necessary. There was no significant differences in subjective and objective parameters between these patients and those who did not need CIC. Patient opinion about the treatment was not affected by CIC. About two thirds (67.2%) of the patients in the study group were satisfied with the results of treatment, and 60.3% would undergo the same procedure again. CONCLUSIONS: TUMT of the prostate is an effective, safe, and acceptable form of treatment for patients with BPH. Longer follow-up is needed to examine the durability of TUMT treatment.

Aged↗
PubMed1998

Lymphoceles after laparoscopic pelvic node dissection.

OBJECTIVE: Lymphocele formation has been infrequently reported as a complication of laparoscopic pelvic lymph node dissection (LPLND). We determined the incidence of clinical and subclinical lymphocele formation in patients undergoing transperitoneal LPLND. METHODS: Charts and radiological records of 111 patients undergoing transperitoneal LPLND at this institution between January 1991 and December 1995 were reviewed to determine the incidence of lymphocele formation. RESULTS: Of 111 patients undergoing LPLND, 12.6% had positive lymph nodes and received hormonal therapy. Radical retropubic (12) or perineal (28) prostatectomy was performed either simultaneously or within 2 weeks in 41% of the node-negative patients. Radiation therapy was the treatment modality in the remaining node negative patients (N = 57). Twenty-three patients undergoing radiation therapy had preplanning pelvic computed tomography (CT) scans 2 to 16 weeks (mean 8.2 weeks) after LPLND. These were reviewed by a single radiologist to determine the presence of subclinical lymphoceles. Seven patients (30.4%) had lymphoceles of varying sizes (3 large and 4 small). Although most were identified on CT scans 4 weeks after the procedure, two were identified on scans 12 and 16 weeks after the procedure (mean 6.5 weeks). None of these patients developed symptoms referable to or had treatment for the lymphocele during a 2 to 37 month follow-up (mean 20 months). Only two patients (3.5%) undergoing LPLND as an isolated procedure had clinical evidence of lymphocele formation, both of which were subsequently confirmed with CT scans (1 large, 1 small). One was treated with CT-guided drainage and sclerosis and the other resolved spontaneously. CONCLUSION: The clinical incidence of lymphocele formation following LPLND remains relatively low. Only a portion of these patients requires intervention. Subclinical lymphoceles, as detected on follow-up CT scans, occur with a much greater frequency. These seldom become symptomatic requiring treatment. Rather, they appear to resolve spontaneously. Nevertheless, clinical suspicion should remain high in order to detect and properly treat symptomatic lymphoceles when they occur.

Combined Modality Therapy↗
PubMed1998

Crossing vessels. Endourologic implications.

The controversy regarding the functional significance of vessels crossing at the ureteropelvic junction is not a new one, though this debate has been resurrected in recent years because of application of endourologic techniques to manage ureteropelvic junction (UPJ) obstruction. The principle limitation of endoscopic treatment of UPJ obstruction is the inferior success rate compared to open dismembered pyeloplasty. The influence crossing vessels may have in affecting both the success rates and complications of endoscopic treatment of UPJ obstruction has yet to be resolved. Crossing vessels may be important for two reasons: (1) they are a potential source of hemorrhage following endoscopic incision, and (2) they may play an etiologic role in UPJ obstruction and therefore may be a reason for failure of endoscopic techniques. This article reviews some of the historical aspects of crossing vessels and explores recent studies that are starting to shed some light on this controversial topic.

Humans↗
PubMed1998

The cell division cycle and the pathophysiology of Alzheimer's disease.

Evidence is growing of a role of apoptosis in neurodegenerative disorders including Alzheimer's disease. Recent research indicates that cell cycle disturbances may promote apoptosis in neurodegenerative diseases. In this commentary we will discuss the control of the cell cycle in mammalian cells in general and in the central nervous system in particular. We then summarize the evidence for cell cycle perturbations in Alzheimer's disease and discuss the possible significance these may have for the development of pathological changes in this disease. Our working hypothesis is that, contrary to previous belief, neurons in the adult human brain are capable of re-entering the cell division cycle. The progression of the cell cycle is normally arrested at an early stage and neurons are able to re-differentiate. However, in Alzheimer's disease the cell cycle is allowed to progress into the G2 phase. At this stage re-differentiation is not possible and the neurons will suffer one of two fates: either they will die via an apoptotic pathway or they may produce Alzheimer-type pathology.

Adult↗
PubMed1998

Age differences in context integration in memory.

This research examined the role of contextual integration in memories of younger and older adults. In 2 experiments, recall of a target picture to a context picture cue was better when sentences were generated that integrated the picture pair and when the picture pairs were already related to each other. Age differences were smallest when sentences were generated for semantically related pairs. Older adults generated the same type sentences as younger adults, although they generated fewer integrations for unrelated pairs. In a 3rd experiment, younger adults could not differentiate between younger- and older-generated sentences from Experiment 1, and the sentences did not differentially affect recall performance. The results are discussed in terms of age differences in self-initiated processing when using context.

Adult↗
PubMed1998

Can a hydrophilic guidewire be resterilized?

The Glidewire (Microvasive, Natick, MA) or Terumo wire (Terumo, Japan) is constructed with a hydrophilic polymer surface that enables easier passage through narrowed lumens in the urinary tract. This study examined the effects of gas sterilization on Glidewire surface structure, slipperiness, and ability to support bacterial growth. Light microscopy at 100x and 400x and scanning electron microscopy at 100 to 1300x were used to compare the surface tips of five new 0.038-inch Glidewires with those resterilized one or three times. The tips were immersed in water prior to standard gas sterilization for operating room equipment. Subjective evaluation of slipperiness involved asking 10 blinded urologists to assess the nature of new and resterilized wires by feel. Support of bacterial growth was assessed by comparing cultures performed on new wires (control) with those of wires incubated with Bacillus stearothermophilus. Microscopy, reviewed by a pathologist, revealed no perceivable surface differences after one and three gas sterilizations. Eight of the urologists noted similar or improved slipperiness of resterilized wires compared with new wires. Bacterial cultures of intentionally infected wire segments showed no growth after standard gas sterilization in all cases. In this study, gas sterilization did not adversely affect the lubricious nature or the surface coating of the hydrophilic coating of Glidewires. Also, gas resterilization was bactericidal to new and used wires that had been infected with a heat-tolerant organism.

Bacteria↗