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Biomedical subjects

T Smith

Publications and source records attributed to T Smith.

At least 253 records · Page 14Linked to original sources
PubMed1998

Osteolysis associated with cemented total knee arthroplasty.

Osteolysis has not been mentioned as a complication or cause of failure of cemented total knee arthroplasties in long-term follow-up studies. We are aware of a single case report of osteolysis after cemented total knee arthroplasty. We report the case of an 87-year-old woman with massive osteolysis beneath a cemented tibial component.

Aged↗
PubMed1998

Clinical course of breast cancer patients with metastases confined to the lungs treated with chemotherapy. The University of Texas M.D. Anderson Cancer Center experience and review of the literature.

PURPOSE: To evaluate the clinical course of patients with a metastatic breast cancer (MBC) confined to the lungs and treated with doxorubicin/cyclophosphamide-containing chemotherapy (DC-CT). PATIENTS AND METHODS: Between 1973 and 1985, 1581 patients with MBC were treated with DC-CT at M.D. Anderson Cancer Center. Data for 88 patients (5.6%) with metastases confined to the lungs were reviewed to correlate various clinical characteristics with response to treatment and survival. RESULTS: The overall response rate was 76% with 33% achieving complete response (CR). The median overall survival time was 22 months (range 1-210). The 10-year survival rate was 9%. The overall response and CR rates were higher for the patients with metastases confined to the lungs (76% and 33%. respectively) than for the remainder of MBC patients (64% and 14%; P < 0.01). The 10-year survival rate was also higher (9% versus 3%, P < 0.01), but there were no differences in median overall survival rate. CONCLUSIONS: This retrospective analysis demonstrated that patients with metastases confined to the lungs treated with DC-CT had a high objective response rate, especially high CR rates, and a median survival comparable to that of our entire population of MBC patients. A small but clinically significant percentage of patients had prolonged survival. Therefore, not all visceral sites are indicators of poor prognosis.

Adult↗
PubMed1998

Adaptation and evaluation of the Liverpool Seizure Severity Scale and Liverpool Quality of Life battery for American epilepsy patients.

The Liverpool Seizure Severity Scale (LSSS) and the Liverpool Quality of Life (LQOL) battery were developed in Great Britain to assess the severity of seizure symptoms and the impact of epilepsy on patients' quality of life. The scales have been validated on British patients, but have not been validated for use with American patients. The objectives of this study were to adapt the scales to the American population and to evaluate their reliability and validity. After modifications recommended by focus groups with patients and epilepsy specialists, the scales were administered to a sample of 90 epilepsy patients who had experienced seizures within the previous 4 weeks. Comparisons of patients with generalized tonic-clonic seizures (n = 58) and partial seizures (n = 32) revealed significant differences on 9 of the 20 items on the LSSS as well as the total score. None of the six LQOL subscales (negative drug effects, positive drug effects, affect balance, sense of mastery, life fulfilment and impact of epilepsy) distinguished patients with different seizure types but five of the six subscales were significantly correlated with seizure severity. The internal consistency and test-retest reliability were adequate for both the LSSS and LQOL. Finally, five of the six LQOL scales were significantly correlated with independent measures of mental health, physical health and role functioning.

Adult↗
PubMed1998

Adaptation and evaluation of the Liverpool Seizure Severity Scale and Liverpool Quality of Life battery for American epilepsy patients.

The Liverpool Seizure Severity Scale (LSSS) and the Liverpool Quality of Life (LQOL) battery were developed in Great Britain to assess the severity of seizure symptoms and the impact of epilepsy on patients' quality of life. The scales have been validated on British patients, but have not been validated for use with American patients. The objectives of this study were to adapt the scales to the American population and to evaluate their reliability and validity. After modifications recommended by focus groups with patients and epilepsy specialists, the scales were administered to a sample of 90 epilepsy patients who had experienced seizures within the previous 4 weeks. Comparisons of patients with generalized tonic-clonic seizures (n = 58) and partial seizures (n = 32) revealed significant differences on 12 of the 20 items on the LSSS as well as the total score. None of the six LQOL subscales (negative drug effects, positive drug effects, affect balance, sense of mastery, life fulfillment and impact of epilepsy) distinguished patients with different seizure types but five of the six subscales were significantly correlated with seizure severity. The internal consistency and test-retest reliability were adequate for both the LSSS and LQOL. Finally, five of the six LQOL scales were significantly correlated with independent measures of mental health, physical health and role functioning.

Adult↗
PubMed1998

The effects of interaction between familial and reproductive factors on breast cancer risk: a combined analysis of seven case-control studies.

In this paper, a combined analysis was performed to study the interaction between familial risk and reproductive life factors. In particular, the interaction between familial risk and breast cell mitotic activity (BCMA), as assessed by duration of ovarian activity, was investigated because of the potential importance of mitotic activity on genetically susceptible cells. The present analysis included 3152 cases and 4404 controls in seven case-control studies from four countries. The interaction effect was estimated in each study separately, then combined using two different methods: a multivariate weighted average and a Bayesian random-effects model. The main effects of reproductive life factors on the risk of breast cancer were in agreement with the previous findings. In particular, an increased duration of BCMA before the first childbirth and over life was found to increase the risk of breast cancer (P < 0.001). Slightly increasing but non-significant, familial risks were observed with increasing number of children (P = 0.17), increasing age at first childbirth (P > 0.2) and increasing duration of BCMA (P > 0.2). There was no modification in familial risk with age at menarche and no clear pattern with menopause characteristics. A weak influence of reproductive and menstrual factors on the familial risk emerged from the present study.

Adult↗
PubMed1998

Distinction of recrudescences from new infections by PCR-RFLP analysis in a comparative trial of CGP 56 697 and chloroquine in Tanzanian children.

OBJECTIVE: To test the efficacy of a new compound drug (CGP 56697) against acute, uncomplicated falciparum malaria. METHOD: Reappearing parasites were analysed by PCR-RFLP within a randomized controlled trial. 130 patients received chloroquine and 130 patients were treated with CGP 56697. Samples from 96 patients with parasitological failure were tested by PCR-RFLP for MSP2 of Plasmodium falciparum. Seven days after treatment 32 patients of the chloroquine control group with reappearing parasites were tested by PCR and one infection was unequivocally determined as a new infection. After 7 days, in the CGP 56697 group, 6 samples were tested in which one new infection was identified. Similar observations were made one and three weeks later in both groups. RESULTS: Although a high multiplicity of infections on admission was observed, there was no significant correlation between multiplicity and either recrudescence or new infection. Patients in both treatment groups with subsequent recrudescent parasites had higher initial mean parasite densities than patients who cleared. Those of the patients with recrudescent parasites who were treated with CGP 56697 had higher initial parasite densities than those treated with chloroquine. The rate of re-infection increased with time as expected in holoendemic areas and appeared to be higher in chloroquine patients. Generally, CGP 56697 showed a superior clearance rate, successfully cleared higher parasite densities and suppressed new infections over a longer period of time. CONCLUSION: The PCR analysis confirmed that reinfections beyond day 7 are significant in areas highly endemic for malaria and showed the necessity of excluding these when estimating 14 day clearance rates. Provided new infections are excluded, the 28-day clearance rate can also be used to determine the efficacy of antimalarial drugs in highly endemic areas, and adds to our knowledge of drug resistance and dynamics of infections in people living in such areas.

Acute Disease↗
PubMed1998

Dose response of various radiation detectors to synchrotron radiation.

Accurate dosimetry is particularly difficult for low- to medium-energy x-rays as various interaction processes with different dependences on material properties determine the dose distribution in tissue and radiation detectors. Monoenergetic x-rays from synchrotron radiation offer the unique opportunity to study the dose response variation with photon energy of radiation detectors without the compounding effect of the spectral distribution of x-rays from conventional sources. The variation of dose response with photon energies between 10 and 99.6 keV was studied for two TLD materials (LiF:Mg,Ti and LiF:Mg,Cu,P), MOSFET semiconductors, radiographic and radiochromic film. The dose response at synchrotron radiation energies was compared with the one for several superficial/orthovoltage radiation qualities (HVL 1.4 mm Al to 4 mm Cu) and megavoltage photons from a medical linear accelerator. A calibrated parallel plate ionization chamber was taken as the reference dosimeter. The variation of response with x-ray energy was modelled using a two-component model that allows determination of the energy for maximum response as well as its magnitude. MOSFET detectors and the radiographic film were found to overrespond to low-energy x-rays by up to a factor of 7 and 12 respectively, while the radiochromic film underestimated the dose by approximately a factor of 2 at 24 keV. The TLDs showed a slight overresponse with LiF:Mg, Cu, P demonstrating better tissue equivalence than LiF:Mg, Ti (maximum deviation from water less than 25%). The results of the present study demonstrate the usefulness of monoenergetic photons for the study of the energy response of radiation detectors. The variations in energy response observed for the MOSFET detectors and GAF chromic film emphasize the need for a correction for individual dosimeters if accurate dosimetry of low- to medium-energy x-rays is attempted.

Biophysical Phenomena↗
PubMed1998

Influence of background correction in the estimation of myocardial uptake of 99mTc labelled perfusion imaging agents.

The effects of different corrections for background activity in the estimation of low organ uptake of radiopharmaceuticals have been examined using myocardial perfusion imaging agents. Estimates of myocardial uptake of 99mTc-labelled MIBI and tetrofosmin were made both at rest and after exercise. Patients were given one or other of the agents (12 MIBI; 17 tetrofosmin) and the measurements at rest and after exercise were made within a week of each other using a planar gamma camera method incorporating an attenuation-corrected, geometric mean technique. Myocardial uptakes were estimated using two different background corrections and also with no background subtraction. Mean values were in the range 1.3 to 3.0% and showed that, for both agents, uptakes estimated with and without background correction could differ by a factor of two. Although the study was not designed to compare myocardial uptakes of the two agents, a background correction which accounted separately for activity in tissue over- and under-lying the heart resulted in similar mean values for tetrofosmin (1.7% both at rest and after exercise) and for MIBI (1.8% rest; 1.9% exercise). For both agents, no significant difference was observed between myocardial uptakes at rest and after exercise measured at about two hours post-injection.

Adult↗
PubMed1998

Energy balance and thermogenesis in rats consuming nonstarch polysaccharides of various fermentabilities.

BACKGROUND: The equivalents of dietary protein, fat, and available carbohydrate as fuels for maintenance (kJ apparent metabolizable energy/kJ maintenance requirement) are known from classical experiments and are similar across species; that for nonstarch polysaccharide (NSP) is undetermined. OBJECTIVES: Our objectives were to determine the energy equivalent of NSP and the thermic responses to NSP. DESIGN: In a randomized block design, 120 rats were treated in groups of 10 for 28 d with a basal diet (control) supplemented with starch and 10 different NSP treatments in amounts between 38 and 92 g/kg basal diet. Cellulose and starch were references. Thermic responses, deduced from body-composition changes and modeling of energy disposition, and energy and substrate excretion were determined. RESULTS: NSP had fermentabilities between 0.01 and 0.93 g/g intake. Fermentability, partial digestible energy, and net metabolizable energy values of NSP were closely related. Generally, 51% of apparent metabolizable energy from NSP (fermentable gross energy) met maintenance requirements. Diet (energy)-induced thermogenesis (DIT) was evident from whole diets. Fermentable NSP supplied net metabolizable energy and caused DIT. After DIT and fermentation were accounted for, NSP-induced thermogenesis was generally -2+/-4% (x+/-SEM) of gross NSP energy, except for an outlying pectic preparation, which was 33% (P< 0.1). CONCLUSIONS: The energy equivalent of NSP was 196 (100/51) kJ/kJ, compared with 128, 105, and 100 for protein, fat, and glucose, respectively, from the classical experiments. With the exception of pectic NSP, NSP does not induce thermogenesis in excess of that associated with DIT and fermentation.

Animals↗
PubMed1998

Members of the olfactory receptor gene family are contained in large blocks of DNA duplicated polymorphically near the ends of human chromosomes.

We have identified three new members of the olfactory receptor (OR) gene family within a large segment of DNA that is duplicated with high similarity near many human telomeres. This segment is present at 3q, 15q, and 19p in each of 45 unrelated humans sampled from various populations. Additional copies are present polymorphically at 11 other subtelomeric locations. The frequency with which the block is present at some locations varies among populations. While humans carry seven to 11 copies of the OR-containing block, it is located in chimpanzee and gorilla predominantly at a single site, which is not orthologous to any of the locations in the human genome. The observation that sequences flanking the OR-containing segment are duplicated on larger and different sets of chromosomes than the OR block itself demonstrates that the segment is part of a much larger, complex patchwork of subtelomeric duplications. The population analyses and structural results suggest the types of processes that have shaped these regions during evolution. From its sequence, one of the OR genes in this duplicated block appears to be potentially functional. Our findings raise the possibility that functional diversity in the OR family is generated in part through duplications and inter-chromosomal rearrangements of the DNA near human telomeres.

Amino Acid Sequence↗
PubMed1998

The effect of distance from home on attendance at a small rural health centre in Papua New Guinea.

BACKGROUND: The willingness of patients in the rural tropics to seek medical care at primary health care facilities is influenced by the distance they have to travel, but few studies have tried to estimate these distance effects. METHODS: Distance decay effects in attendance rates were estimated from a database of 4348 attendances at a rural health centre in Papua New Guinea, linked to demographic and house position data for the catchment population. Small-scale spatial patterns and differences between diagnoses, age groups and gender are described. RESULTS: Attendance decreased markedly with distance both overall (50% decrease at 3.5 km) and for patients with malaria or acute respiratory infections. This decrease was non-linear (on log scale) with distance. Although constant over time, there were big differences in this distance effect among age and gender groups: Female patients showed less distance decay in adolescents and adults, but higher in the infant group. Spatial patterns accounted for 32% of the variation in age- and gender-specific attendance rates. Of the spatial effects more than 50% were due to distance effects. CONCLUSIONS: Distance effects were similar in magnitude to those reported elsewhere, suggesting that distance effects may be generalizable to many parts of the rural tropics. The non-linearity of distance decay implies that a bell-shaped demand function should be used in health planning.

Adolescent↗
PubMed1998

Recovery of evoked potential amplitude after cerebral arterial air embolism in the rabbit: a comparison of the effect of cardiopulmonary bypass with normal circulation.

BACKGROUND: Cerebral arterial air embolism (CAAE) may cause neurologic injury during cardiac surgery. It is not known whether cardiopulmonary bypass (CPB) increases or decreases brain injury from CAAE compared with the normal circulation. METHODS: A model of CAAE was produced by injection of 50 microl/kg air into the internal carotid artery of methohexital-anesthetized New Zealand white rabbits. Somatosensory-evoked potential (SSEP) amplitude was measured serially as a marker of neurologic recovery. In experiment A, saline rather than air was injected to control for surgical manipulation and time in CPB (n = 4) and nonheparinized non-CPB (n = 4) animals. In experiment B, 50 microl/kg air was injected in CPB (n = 11) and nonheparinized non-CPB (n = 11) animals. In experiment C, non-CPB animals (n = 6) were given heparin according to the same protocol as for CPB. RESULTS: In experiment A, SSEP latencies and amplitudes did not differ between CPB and non-CPB conditions. In experiment B, there was no SSEP recovery 5 min after CAAE in either CPB or non-CPB animals. Thereafter, SSEP recovery was less in CPB animals than in non-CPB animals at 30 min (9 +/- 12% vs. 29 +/- 20%; P = 0.009) and 60 min (18 +/- 15% vs. 39 +/- 22%; P = 0.030) after CAAE. Ninety-minute SSEP recovery did not differ between CPB and non-CPB groups (at 24 +/- 19% vs. 39 +/- 24%, respectively; P = 0.146). In experiment C (heparinized non-CPB), SSEP recovery 5, 30, 60, and 90 min after CAAE was 67 +/- 48%, 72 +/- 47%, 80 +/- 35%, and 77 +/- 35%, respectively. CONCLUSIONS: Somatosensory-evoked potential recovery after CAAE is no better (and is probably worse) during CPB than during normal circulation. The adverse effect of CPB occurs despite heparinization, which, under non-CPB conditions, appears to be protective. Therapies in addition to heparin are needed during CPB to reduce neurologic injury from CAAE.

Animals↗