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Biomedical subjects

J R Anderson

Publications and source records attributed to J R Anderson.

At least 253 records · Page 14Linked to original sources
PubMed1992

Automaticity and the ACT* theory.

An explanation of automaticity within the framework of the Adaptive Control of Thought (ACT*) production system theory (Anderson, 1983, 1987) is presented. There is no automaticity mechanism per se in ACT*. This is as we would expect it to be. It would be the exception rather than the rule that we would find in a scientific theory mechanisms that directly correspond to natural language concepts. The critical question is whether ACT* can give an account of the phenomena associated with the term automaticity. This article is structured as follows: First, I will try to identify the phenomena of automaticity to be explained, then give a brief overview of the ACT* theory, and finally explain how these phenomena of automaticity are to be understood in terms of the theory.

Attention↗
PubMed1991

Regulatory role of parasites: impact on host population shifts with resource availability.

Effects of infections by the ciliate Lambornella clarki on larval populations of its mosquito host Aedes sierrensis were examined in laboratory and field studies. When host populations developed with sufficient food, mortality from parasites was additive and reduced the number of emerging mosquitoes. For food-limited populations, mortality was compensatory or depensatory; emerging adults were as or more abundant with higher average fitness than those from uninfected control populations. When nutrients were scarce, parasitic infections relaxed larval competition and increased per capita food by reducing host abundance. Food limitation altered larval feeding behavior, reducing horizontal transmission and subsequent mortality from parasitism.

Aedes↗
PubMed1991

Nasal tip projection. Quantitative changes following rhinoplasty.

Fifty-one patients were enrolled in a study and underwent primary rhinoplasty. Serial nasal tip projection measurements were made preoperatively, intraoperatively, and 6 months postoperatively. Actual changes in measured nasal tip projection were evaluated with respect to preoperative goals and specific procedures used to accomplish these goals in the nasal tip. Several useful observations are made from these data: (1) The most important components of nasal tip projection in the postsurgical nasal tip are the medial crura, their attachment to the caudal septum, and the presence of additional cartilaginous grafts placed between the medial crura or beneath the crural feet. (2) Actual nasal tip projection will decrease postoperatively, unless measures to increase the length and strength of the medial crural segment are taken (ie, McCollough-modified Goldman tip procedure, cartilage struts, plumping grafts, etc), regardless of the preoperative goal. (3) The double-dome unit procedure is effective in narrowing the wide or bulbous lobule but alone does not permanently increase nasal tip projection. (4) Conservative tip procedures, such as a complete strip, result in decreased nasal tip projection and should therefore be used in patients in whom retrodisplacement of the nasal tip is the intended result.

Adult↗
PubMed1991

Results of surgery for duodenal ulcer: assessment by patients.

A questionnaire was administered to 224 patients who had undergone 246 operations for duodenal ulcer to see how well this correlated with Visick grading and to provide insight into the patients' feelings about the results of their surgery. The patients were divided into three groups by Visick grade: good (grade I, n = 70), satisfactory (grades II and IIIs, n = 104) and poor (grades IIIu and IV, n = 72). The distribution of questionnaire responses in each group was statistically different (P less than 0.01). Dividing the questionnaire responses into three corresponding groups, 72 per cent of patients assigned themselves to the same group as their Visick grade. Three observations were made regarding the Visick system: recurrent ulceration is over-scored and should be included only if symptomatic; grading should acknowledge a wider range of symptoms related to ulcer disease and its treatment; only three grades are necessary.

Adult↗
PubMed1991

Subtotal cholecystectomy.

Subtotal cholecystectomy has been carried out on 11 patients during a 5-year period, constituting 3.8 per cent of cholecystectomies performed during this time. The indications were severe inflammation/fibrosis in six patients, portal hypertension in three and the Mirizzi syndrome in two patients. There were no deaths and only minor in-hospital morbidity. One patient developed a common bile duct stone 21 months after the operation. None of the remaining patients has to date developed postcholecystectomy sequelae (mean follow-up period 29 (range 1-62) months). Subtotal cholecystectomy is a safe, straightforward and definitive operation in patients for whom standard cholecystectomy could be dangerous, and is a more attractive proposition than cholecystostomy.

Acute Disease↗
PubMed1991

Autologous bone marrow transplantation for patients with relapsed Hodgkin's disease.

PURPOSE: High-dose therapy and autologous bone marrow transplantation (ABMT) are being increasingly utilized for the management of patients with relapsed Hodgkin's disease. Because patients with relapsed Hodgkin's disease often initially respond to salvage chemotherapy regimens, ABMT is frequently delayed until late in the course of the disease. The optimal timing for ABMT has not been identified. The purpose of this study was to determine the value of ABMT earlier in the course of Hodgkin's disease. PATIENTS AND METHODS: We treated 70 patients between October 1984 and October 1988 with high-dose cyclophosphamide, carmustine, and etoposide, followed by infusion of previously cryopreserved autologous bone marrow, and analyzed the results to determine the impact of timing of ABMT on treatment outcome. One (17 patients), two (24 patients), or three or more (29 patients) chemotherapy regimens had failed in patients before ABMT. RESULTS: The results for all 70 patients included a complete remission rate of 59%, an early death rate of 11%, a 4-year survival of 47%, and 27% of all treated patients alive and in complete remission at 4 years. The median follow-up for patients remaining in complete remission is 56 months (range 26 to 73 months). The frequency of achieving a complete remission was higher in patients in whom fewer regimens had failed before ABMT (i.e., 82% versus 58% versus 45%, p = 0.02), as was the 4-year disease-free survival (i.e., 44% versus 33% versus 21%, p = 0.04). CONCLUSION: ABMT is a more effective therapy when used early for patients with relapsed Hodgkin's disease.

Adolescent↗
PubMed1991

Parasitism of newly-hatched Aedes sierrensis (Diptera: Culicidae) larvae by Lambornella clarki (Ciliophora: Tetrahymenidae) following habitat flooding.

Host-parasite interactions between Lambornella clarki (Ciliophora: Tetrahymenidae) and its natural host, Aedes sierrensis (Diptera: Culicidae), were studied in newly flooded treeholes in northern California between 1986 and 1989. First instar host larvae hatched within 1 to 4 hr of flooding, while free-living trophonts of L. clarki appeared between 7 and 24 hr. As early as 24 hr after flooding, ciliates initiated the first parasite cycle by forming cuticular cysts on first instar larvae; by 64 hr, cysts were observed on larvae collected from all positive holes during all years. While larvae with as many as 12 cysts were observed, most supported only 1 cyst, and successful infections were established by the entry of a single ciliate into the host's hemocoel. Among treehole populations, the proportion of larvae with L. clarki cysts ranged from 2 to 100% at 48 hr indicating that enzootics and epizootics develop rapidly in newly flooded treeholes. Average attack rates from all holes by year ranged between 17.0 and 44.4%. Ciliates began entering hosts 48 to 72 hr after flooding, but some larvae escaped parasitization by molting to the second instar before ciliates penetrated the cuticle. In some treeholes, opportunistic microorganisms entered larvae with the invading ciliates and killed both the host and parasite.

Aedes↗
PubMed1991

The will and the ways: development and validation of an individual-differences measure of hope.

Defining hope as a cognitive set that is composed of a reciprocally derived sense of successful (a) agency (goal-directed determination) and (b) pathways (planning of ways to meet goals), an individual-differences measure is developed. Studies demonstrate acceptable internal consistency and test-retest reliability, and the factor structure identifies the agency and pathways components of the Hope Scale. Convergent and discriminant validity are documented, along with evidence suggesting that Hope Scale scores augmented the prediction of goal-related activities and coping strategies beyond other self-report measures. Construct validational support is provided in regard to predicted goal-setting behaviors; moreover, the hypothesized goal appraisal processes that accompany the various levels of hope are corroborated.

Adaptation, Psychological↗
PubMed1991

Examination of cardiorespiratory changes during upper gastrointestinal endoscopy. Comparison of monitoring of arterial oxygen saturation, arterial pressure and the electrocardiogram.

Critical events including hypoxaemia, arrhythmias and myocardial ischaemia may occur more frequently during endoscopic procedures than during anaesthesia. A study was undertaken to assess the cardiovascular changes and to evaluate suitable monitoring techniques to detect critical events during sedation and endoscopy. Twenty patients scheduled to undergo a prolonged endoscopic procedure which required deep sedation were studied. Continuous recordings of electrocardiogram, heart rate and arterial oxygen saturation were made and arterial pressure was recorded at one-minute intervals. The study commenced immediately before administration of sedatives, continued for the duration of the examination and for one hour following the examination. Oxygen saturation decreased in all patients during the examination to a mean of 82.9% (SD 11.9), and remained below baseline for the duration of the examination and into the recovery period. Statistically significant increases and reductions of systolic arterial pressure and rate-pressure product were found during the procedures compared with baseline values recorded before administration of sedatives. Sixteen of the 20 patients developed tachycardia during the examination. Ten patients developed ectopic foci which were supraventricular, ventricular or both in origin. Electrocardiogram changes resolved during the recovery period. Myocardial ischaemia was assessed by S-T segment depression and a significant correlation was found between S-T segment depression and hypoxaemia, although the magnitude of the S-T depression was small and may not have been detected clinically. No correlation was found between S-T segment depression and arterial pressure, heart rate or rate-pressure product.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Conservative surgery in multiple cusp involvement in tricuspid valve endocarditis.

Tricuspid and mitral valve endocarditis caused by Staphylococcus epidermidis in a 57 year old previously healthy man with no history of drug abuse presented as bi-ventricular failure and multiple episodes of pulmonary emboli. He was treated for four weeks with intravenous antibiotics and had serial echocardiographic assessment of the vegetation on the tricuspid valve. This was followed by mitral valve replacement, local excision of vegetation from all the three cusps of the tricuspid valve, and autologous pericardial reconstruction of these cusps with functional assessment by perioperative transoesophageal echocardiography. Postoperative cardiac function was excellent and serial echocardiographic assessment confirmed satisfactory tricuspid valve function. This is believed to be the first recorded case in which autologous pericardial repair was used to reconstruct all the three cusps in a tricuspid valve after excision of vegetations.

Endocarditis, Bacterial↗
PubMed1991

CHLVPP chemotherapy with involved-field irradiation for Hodgkin's disease: favorable results with acceptable toxicity.

Patients with Hodgkin's disease who were previously untreated with chemotherapy received the chlorambucil, vinblastine, procarbazine, and prednisone (CHLVPP) regimen plus limited involved-field radiation therapy for treatment of Hodgkin's disease through the Nebraska Lymphoma Study Group. One hundred patients, 87 with newly diagnosed Hodgkin's disease and 13 who relapsed after receiving previous radiation therapy, were treated with this regimen between 1982 and 1989. Complete remissions (CRs) were obtained in 88 of 100 patients (88%), and there have been a total of eight relapses. The overall 3-year failure-free survival was 76%, with good-prognosis patients (ie, Karnofsky performance status greater than or equal to 80) having a 3-year failure-free survival of 87%. Toxicity with this regimen was minimal, with neutropenic fevers reported in 13% of the patient population, moderate alopecia in 5%, and mild to moderate nausea and vomiting in 11% of the patients. As primary induction therapy for Hodgkin's disease, CHLVPP is an effective regimen with a high patient acceptance profile.

Adolescent↗
PubMed1991

The surgical treatment of ingrowing toenails.

Two prospective studies of ingrowing toenail management were conducted. In the first, 163 patients (204 ingrowing nail edges) who had not had previous surgery were randomised and treated by total nail avulsion, nail edge excision, or nail edge excision with phenolisation of the germinal matrix; recurrence rates one year postoperatively were 73%, 73% and 9% respectively. In the second study, 63 ingrowing nail edges which had recurred after previous operations underwent nail edge excision and phenolisation. There was a 5% recurrence rate and 5% incidence of dystrophy of the nail one year after operation.

Adolescent↗
PubMed1991

Nalbuphine after major gynecologic surgery. Comparison of patient-controlled analgesia and intramuscular injections.

A randomized investigation compared the efficacy and safety of nalbuphine administered by two methods, a patient-controlled infuser system and intramuscular (IM) injections, after major gynecologic surgery. Forty-seven patients were randomly assigned to receive nalbuphine by either method. The 22 patients using the infuser were given a 2.0-mg, incremental dose with a 10-minute lock-out interval between doses. A similar group receiving 10-15 mg IM every three hours served as the control. Misprogramming, overdosage, depressed respiration and drug dependence were not encountered. Self-administration provided equally satisfactory sedation and more immediate pain relief without painful injections. Although patients with the infuser had the ability to self-administer more medication, they did not use higher doses of nalbuphine than did the IM group. The additional cost of the infuser system was offset by the satisfaction expressed by the patients and by the improved nursing efficiency. Nalbuphine administered with a patient-controlled infuser provided an effective balance between analgesia and sedation and offered advantages over IM injections.

Adult↗
PubMed1991

Interpretation of survival data in clinical trials.

The results of therapeutic interventions can often be best described through the distribution of times to some event. The most obvious example of this is actual survival (time to death) and the methods used in the analysis of "time to event" data are broadly referred to as "survival analysis." However, survival analysis really refers to the evaluation of time to any definable event. The goals of survival analysis are to estimate the "time to event" distribution for a defined group of patients and to compare the experience of different groups of patients. In the case of a chronic disease like cancer, the analysis is complicated because the event of interest may not yet have taken place or the patient may have been lost to follow-up. Here we review the standard techniques used in the analysis of survival data and discuss important related issues.

Clinical Trials as Topic↗
PubMed1991

[Reactions to mirror in three species of lemurs (Lemur fulvus, L. macaco, L. catta)].

Reactions when confronted with their own reflection in a mirror were observed in three captive groups of lemurs: L. fulvus, L. macaco and L. catta. The ability of a mirror to induce social facilitation of drinking was also studied in one individual of each species. As previously observed in monkeys, the three groups of lemurs showed much more attention to the mirror than to a non-reflective surface, especially nasal contacts. Only L. fulvus showed habituation to the mirror with successive presentations. No social behaviours were directed towards the reflection, in contrast to descriptions of mirror-image reactions in monkeys, and the mirror did not produce an effect of social facilitation. The results suggest that the mirror elicits a diminished social reaction in lemurs compared to monkeys, perhaps due to the absence of relevant olfactory stimuli.

Animals↗