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Biomedical subjects

A Lee

Publications and source records attributed to A Lee.

At least 307 records · Page 17Linked to original sources
PubMed1998

Esophageal stents may interfere with the swallowing reflex: an illustrative case history.

Dysphagia is an important and distressing symptom which has a significant impact on the quality of life of patients with carcinoma of the esophagus. Although endoscopic palliation of dysphagia due to unresectable or recurrent esophageal carcinoma can be provided by esophageal dilatation and intubation, laser ablation, injection of alcohol or sclerosants, or brachytherapy, these techniques are often unsuitable for the palliation of high esophageal tumors. We present a patient with recurrent carcinoma of the proximal esophagus who developed an inability to swallow as a complication of intubation with an esophageal stent. The dysphagia improved dramatically after the stent was removed.

Aged↗
PubMed1998

Neural networks for recognizing patterns in cardiotocograms.

The cardiotocogram (CTG) is commonly used for routine fetal monitoring in the delivery room. A major problem is that the interpretation of the CTG trace requires experienced specialists. In order to avoid long gaps between the detection of a suspicious pattern and the intervention, the CTG has to be checked in short intervals. An automated monitoring system at the obstetric site can reduce such delays. Therefore, an alarm system immediately reporting suspicious events has been built. The focus of our study was put on the question whether AI techniques such as neural networks are suited to the task of recognizing patterns in the CTG trace. In a comparative study, their performance was evaluated against that of conventional methods. The neural networks turned out to provide significantly better results than the tested conventional methods.

Cardiotocography↗
PubMed1998

Preparation and biological activity of novel tricyclic GPIIb/IIIa antagonists.

Antagonists of the glycoprotein GPIIb/IIIa are a promising class of antithrombotic agents offering potential advantages over present antiplatelet agents (i.e., aspirin and ticlopidine). Novel tricyclic nonpeptidal GPIIb/IIIa antagonists have been prepared and evaluated in vitro as antagonists of fibrinogen binding to the purified GPIIb/IIIa receptor and as inhibitors of platelet aggregation. The work presented demonstrates the robustness of the benzodiazepinedione (BZDD) scaffold, which can be functionalized at the N1-C2 amide as well as at C7, to provide structural diversity and allow optimization of the physiochemical and pharmacological properties of the BZDD based GPIIb/IIIa antagonists. In addition, the resulting new class of tricyclic GPIIb/IIIa antagonists could be used to probe for additional binding interactions on the GPIIb/IIIa receptor and perhaps lead to BZDD based GPIIb/IIIa antagonists with increased potency. The tricyclic molecules reported herein demonstrate that a heterocyclic ring can be fused to the benzodiazepinedione scaffold with retention of anti-aggregatory potency and in the case of tetrazole 30i, increased potency relative to the bicyclic analogue 1c.

Benzodiazepines↗
PubMed1998

The tyrosine-containing cytoplasmic tail of CD1b is essential for its efficient presentation of bacterial lipid antigens.

CD1b is an antigen-presenting molecule that mediates recognition of bacterial lipid and glycolipid antigens by specific T cells. We demonstrate that the nine-amino acid cytoplasmic tail of CD1b contains all of the signals required for its normal endosomal targeting, and that the single cytoplasmic tyrosine is a critical component of the targeting motif. Mutant forms of CD1b lacking the endosomal targeting motif are expressed at high levels on the cell surface but are unable to efficiently present lipid antigens acquired either exogenously or from live intracellular organisms. These results define the functional role of the CD1b targeting motif in a physiologic setting and demonstrate its importance in delivery of this antigen-presenting molecule to appropriate intracellular compartments.

Amino Acid Sequence↗
PubMed1998

Relationship between abdominal aortic aneurysm wall compliance and clinical outcome: a preliminary analysis.

BACKGROUND: Aortic compliance, as measured by the pressure-strain elastic modulus (Ep) and stiffness (B), may allow a more precise estimate of abdominal aortic aneurysm rupture risk than size alone. AIM: To determine the relationships between AAA compliance, size, growth, and clinical outcome. METHODS: One-hundred and twelve patients with initially non-operated AAA (86 men, 26 women, mean age 73 years), recruited from five centres, underwent baseline compliance measurements and were then followed for a median of 7 (range 2-18) months; 85 patients underwent repeated measurements (median 3, range 2-5) 3-6-monthly over a median of 12 (range 3-18 months). RESULTS: Seven patients have ruptured and 16 have undergone repair of non-ruptured AAA. AAA that ruptured had significantly lower Ep and B (more compliant). In AAA that ruptured or required repair there was an inverse relationship between diameter and Ep and B. In those undergoing repeated measurements AAA expansion was only associated with a significant increase in Ep and B in non-operated patients. CONCLUSIONS: Baseline AAA compliance was significantly related to rupture and the future requirement for operative repair. Failure of compliance to increase with size may be a marker for rapid growth, developmental symptoms and rupture.

Aged↗
PubMed1998

Quality of parenting and vulnerability to depression: results from a family study.

BACKGROUND: We examined a group of subjects at familial risk of depression and explored the relationship between the perceptions of parents and a history of depression. We also investigated: (a) whether any difference in perceived parenting found between those with and without a past history of depression was an artefact of the depression; and (b) whether the relationship between parenting and depression was explained by neuroticism. METHOD: We took a sample of first-degree relatives selected from a family study in depression and subdivided them by their history of mental illness on the SADS-L, into those: (a) without a history of mental illness (N = 43); and (b) those who had fully recovered from an episode of RDC major depression (N = 34). We compared the perceptions of parenting, as measured by the Parental Bonding Instrument (PBI), in these two groups having adjusted for the effect of neuroticism and subsyndromal depressive symptoms. We also had informants report on parenting of their siblings, the latter being subdivided into those with and without a past history of depression. RESULTS: Relatives with a past history of depression showed lower care scores for both mother and father combined compared with the never ill relatives. The presence of a history of depression was associated with a non-significant reduction in the self-report care scores compared to the siblings report. Vulnerable personality (as measured by high neuroticism) and low perceived care were both found to exert independent effects in discriminating between the scores of relatives with and without a history of depression and there was no interaction between them. CONCLUSION: This study confirmed that low perceived parental care was associated with a past history of depression, that it was not entirely an artefact of having been depressed, and suggested that this association was partially independent of neuroticism.

Adult↗
PubMed1998

Stability of alkoxycarbonylamidine prodrugs.

PURPOSE: Alkoxycarbonylamidine prodrug modification was used to mask the positively-charged amidine moiety of an Arg-Gly-Asp peptidomimetic and enhance oral bioavailability. The aqueous stability of ethoxycarbonylamidine (ECA), ethanethiocarbonylamidine (ETCA) and phenoxycarbonylamidine (PCA) prodrugs was examined. METHODS: Degradation was followed by RP-HPLC and rate constants were determined from a degradation scheme defined by product analysis. RESULTS: ECA gave a pH of maximum stability at pH approximately 7 and was independent of pH below pH approximately 4. A novel degradation pathway of ECA, conversion to ethoxycarbonyl- aminocarbonyl, was observed below pH 7. The relative rates below pH 7 were ECA approximately ETCA < PCA, in the same order of decreasing pKa of the conjugate acid of the substituted amidino group. Base-catalyzed cleavage of ECA to yield the amidine derivative gave the relative rates ECA < ETCA < PCA, in agreement with the decreasing pKa of the leaving groups. CONCLUSIONS: The observed rate constants at all pHs were small enough that only 5-30% (depending on the substituent) undesirable degradation is predicted during transit time of the gut. The spontaneous post-absorptive conversion to the amidine drugs at neutral pH is predicted to be 6x greater for the PCA than the ECA prodrugs.

Amidines↗
PubMed1998

Hello and goodbye: a study of social engagement in autism.

We videotaped 24 children, adolescents, and young adults with autism, individually matched for chronological age and verbal mental age with 24 nonautistic persons with mental retardation, for their spontaneous and prompted greetings and farewells towards an unfamiliar adult. Compared with control subjects, those with autism were less likely to offer spontaneous verbal and nonverbal gestures of greeting and farewell, and were less likely to establish eye contact even when they were offered a greeting. There were also fewer autistic subjects who smiled, or who waved goodbye. Results corresponded with raters' subjective judgments of participants' interpersonal engagement with the stranger. One interpretation of the findings is that they reflect a relative lack of intersubjective engagement by autistic individuals.

Autistic Disorder↗
PubMed1998

Early postoperative emergencies requiring an intensive care team intervention. The role of ASA physical status and after-hours surgery.

To examine the risk factors of early postoperative emergencies that required an intensive care team intervention, a matched nested case-control study (34 cases and 126 controls) was conducted. Over a 17-month period, the incidence of early postoperative emergencies occurring within 48 h of surgery was 0.21% (95% confidence intervals (CI): 0.14%-0.30%). The intensive care team treated two cardiac arrests and three respiratory arrests. The major physiological changes which led to ward staff summoning an intensive care team were hypotension (13 cases) and a decreased level of consciousness (nine cases). Significant associations with early postoperative emergencies were high ASA (> or = IV) physical status grades (odds ratio: 4.51, 95% CI: 1.24-16.40) and surgery performed outside normal working hours (odds ratio: 4.40, 95% CI: 1.41-13.69). High-risk patients may benefit from a visit by a postoperative care team during the early postoperative period but this requires further evaluation.

Adult↗
PubMed1998

Use of indapamide in hospital and community clinics and its effect on plasma potassium in Chinese patients.

OBJECTIVES: To investigate the usage pattern of indapamide and other antihypertensive drugs in patients attending a community-based government outpatient clinic (GOPC) or a hospital-based specialist clinic (SC). The plasma potassium concentrations of patients receiving indapamide and other diuretics were also examined. METHOD: Prescriptions from the SC and the GOPC were reviewed and collected during January 1998. Patients' plasma potassium concentrations and the date of initiation of each medication were retrieved from the hospital computer databases at SC. An age- and sex-matched control group of patients on non-diuretic antihypertensive drugs was identified. RESULTS: A total of 1648 and 773 prescriptions were collected from the SC during a 1-week period and GOPC during a 1-month period, respectively. Approximately half (45%) of the patients received antihypertensive treatment. Indapamide was five times more frequently prescribed in GOPC than SC (84.7 vs. 17.7%, P<0.001). Calcium channel blocking agents were the commonest antihypertensive drugs used in both clinics. The mean plasma potassium concentration of patients taking indapamide was lower than that of the control group (P = 0.037). Multiple linear regression analysis showed that consumption of indapamide (P =0.002) and duration of diuretic therapy (P = 0.023) were significantly related to changes in plasma potassium concentrations [multiple regression equation for potassium level = 4.09-0.145 (thiazide = 1)-0.377 (indapamide = 1) -0.00468 (duration of diuretic therapy in months)]. CONCLUSION: Indapamide was used extensively in the community clinic and less in the hospital-based outpatient clinic. Patients receiving indapamide had a significantly lower plasma potassium concentration as compared to other diuretics or antihypertensive groups and this was predicted by a multiple linear regression model. Monitoring plasma electrolytes before initiation of indapamide treatment and at regular intervals thereafter is essential for detecting the hypokalaemia that may occur in Chinese patients.

Aged↗
PubMed1998

The long-term effects of prostatic infarction in the rat.

OBJECTIVE: To evaluate the long-term effects of infarction, which usually induces organ atrophy, on the prostate by examining the changes occurring in rat ventral prostate after infarction. MATERIALS AND METHODS: The unilateral arteriolar branches to the ventral prostate were electrocauterized under an operative microscope in 10 adult rats. The gross and histological changes of the treated lobes of the ventral prostate were compared with those of untreated control lobes in the same rats 12 weeks later. RESULTS: The size and mean (SD) weight of the treated lobes decreased markedly, to 148 (34) mg, compared with those of the controls, at 698 (62) mg (P<0.01). The treated lobes were composed of both normal and atrophic glandular tissue. CONCLUSION: Prostatic atrophy can be induced by infarction in the rat; prostatic infarction might have potential as a new therapeutic strategy in the treatment of benign prostatic hyperplasia.

Animals↗
PubMed1998

Doppler waveforms from the pulmonary arterial system in normal fetuses and those with pulmonary hypoplasia.

Color, pulsed and power Doppler were used to image the fetal pulmonary vasculature in 150 normal pregnancies and ten pregnancies in which the fetus had bilateral multicystic dysplastic kidney disease (MCDK) and associated pulmonary hypoplasia. The normal fetuses had a high resistance pattern in the main pulmonary artery vasculature. There were no significant changes in the resistance of the main pulmonary artery, right pulmonary artery and left pulmonary artery, with increasing gestational age. In the peripheral pulmonary arteries the resistance was less with an increase in diastolic flow, with advancing gestation. All fetuses with MCDK died. This group did not have significantly different Doppler waveforms in the main pulmonary arteries, but Doppler signals from the peripheral pulmonary arteries showed a high resistance pattern quite different from that of normal fetuses. Doppler measurements of the peripheral pulmonary artery may give additional information useful in diagnosing pulmonary hypoplasia.

Case-Control Studies↗
PubMed1998

The development of self-perceptions of ability and achievement goals and their relations in physical education.

This study examined the development of self-perceptions of ability and achievement goals and their relationships in physical education. Three hundred and eight students in 4th, 8th, and 11th grades completed questionnaires assessing their goal orientations, conceptions of ability, and perceived competence in physical education. Analyses assessing grade-related changes in conceptions of ability and achievement goals showed that as the students progressed from grades 4 through 11, they were more likely to: (a) interpret ability as a stable capacity that may limit or increase the effect of effort on performance and (b) become ego-oriented. Analyses assessing relationships between variables of interest across grade level revealed that achievement goals were related to different conceptions of ability, students' self-ratings were significantly positively correlated to their teachers' ratings of their competence, and no consistent relationships emerged between achievement goals and perceived competence.

Achievement↗
PubMed1998

Comparison of continuous and intermittent administration of extradural bupivacaine for analgesia after lower abdominal surgery.

We have compared intermittent bolus and continuous infusion of extradural local anaesthetic for pain relief in a randomized, double-blind study of 48 patients who underwent major abdominal gynaecological surgery. Each patient received 5 ml of 0.375% bupivacaine hourly, either as a bolus over 5 min or as a constant infusion. Patients who received the intermittent administration technique maintained a more extensive sensory block, reported marginally better analgesia and had a lower requirement for rescue medication. The intermittent bolus technique was not associated with an increase in side effects.

Adult↗
PubMed1998

Effect of graft reperfusion on haemodynamics and gas exchange during liver transplantation.

We have documented the changes in gas exchange, haemodynamic state and associated physiological variables which occurred after graft reperfusion in 20 patients undergoing uncomplicated orthotopic liver transplantation. Gas exchange was measured during constant ventilation using a metabolic monitor. After reperfusion, there were increases in VO2 (mean increase 57 (SD 25) ml min-1) (P < 0.001), VCO2 (mean increase 38 (17) ml min-1) (P < 0.001) and PaCO2 (mean increase 0.88 (0.56) kPa) (P < 0.001). These were associated with increases in cardiac output (1.2 (1.0) litre min-1 m-2) (P < 0.001) and mean pulmonary artery pressure (9 (6) mm Hg) (P < 0.001). There was a decrease in standard bicarbonate concentration (0.96 (1.6) mmol litre-1) (P < 0.02) and increase in hydrogen ion concentration (8.15 (5.9) mmol litre-1) (P < 0.001) consistent with the release of an acid load from the graft and previously ischaemic tissues. The increases in PaCO2 and hydrogen ion concentration were significantly larger in patients in whom venovenous bypass was used during the anhepatic period compared with the "piggyback" surgical technique. We found correlations between the changes in PaCO2 and VCO2 (r2 = 0.25, P < 0.02), cardiac output and VCO2 (r2 = 0.34, P < 0.01), and cardiac output and VO2 (r2 = 0.34, P < 0.01). We conclude that major alterations in gas exchange occur after reperfusion which result from alterations in metabolic rate and haemodynamic changes. These may be clinically relevant, particularly in patients at risk of cerebral oedema.

Adult↗