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Biomedical subjects

N Morris

Publications and source records attributed to N Morris.

At least 37 records · Page 2Linked to original sources
PubMed1997

Galanin-immunoreactive synaptic terminals on basal forebrain cholinergic neurons in the rat.

Previous studies have indicated that galanin is one of the most abundant peptides in the basal forebrain and that it has a significant modulatory influence on cholinergic transmission. The aim of the present study was to use a light electron microscopic correlation technique to determine whether galanin-immunoreactive terminals form synaptic contacts with basal forebrain cholinergic cells of the rat. Sections from fixed-perfused brains were stained at the light and electron microscopic levels for galanin and choline acetyltransferase immunoreactivity in the same section by using a dual-colour immunohistochemical method. The results showed that galanin-immunoreactive axonal terminals are unevenly distributed in the medial septal nucleus, the diagonal band, and the nucleus basalis. Galanin-positive synapses were most prominent on choline acetyltransferase-positive neurons in the lateral parts of the nucleus of the diagonal band and in the posterior half of the nucleus basalis, which is where there was the greatest overlap between the distribution of galanin-immunoreactive terminals and choline acetyltransferase-positive neurons. The origins of these galanin-positive terminals are not known, but the results confirm that the basal forebrain galaninergic system has a synaptic influence on basal forebrain cholinergic neurons in the rat.

Animals↗
PubMed1997

Loss of decorin from the surface zone of articular cartilage in a chick model of osteoarthritis.

The objective of this study was to immunolocalize decorin and to assess changes as a result of pyridoxine (PN) deficiency in chick articular cartilage from femoral condyles. After maintenance on a normal diet for the first two weeks after hatching, 15 broiler chickens were deprived of this vitamin for 6 weeks. It was previously shown that the ankle joints of PN-deficient animals are swollen with effusions. They also present an abnormal gait, enlarged bony margins, and fissuring of the articular cartilages. Milder changes (no fissures) were also shown in the knee joints. Data from a previous study were suggestive that sulfated glycosaminoglycans are lost from the knee cartilage surface into synovial fluid. The current study was focused on the small proteoglycan, decorin, which coats the surface of collagen fibrils and may regulate their morphology. To examine decorin in normal and PN-deficient articular cartilage, a monoclonal antibody to an epitope on the protein core of decorin was used for immunohistochemical staining of tissue sections and for Western Blot analysis of cartilage extracts. Reduction of staining with the antibody was demonstrated in the tangential surface zone of PN-deficient cartilage, and Western Blot analysis showed reduced intensity of decorin bands compared to normal controls. These data suggest that a lack of decorin may play a role in the enlargement of collagen bundles in the tangential zone of PN-deficient articular cartilage as observed in a previous electron microscopic study.

Animals↗
PubMed1996

Adherence to national guidelines for drug treatment of suspected acute myocardial infarction: evidence for undertreatment in women and the elderly.

BACKGROUND: Evidence-based guidelines for the treatment of patients with acute myocardial infarction (AMI) have been published and disseminated by the American College of Cardiology and the American Heart Association. Few studies have examined the rates of adherence to these guidelines in eligible populations and the influence of age and gender on highly effective AMI treatments in community hospital settings. METHODS: Medical records of 2409 individuals admitted to 37 Minnesota hospitals between October 1992 and July 1993 for AMI, suspected AMI, or rule-out AMI, and meeting electrocardiographic, laboratory, and clinical criteria suggestive of AMI were reviewed to determine the proportion of eligible patients who received thrombolytic, beta-blocker, aspirin, and lidocaine hydrochloride therapy. The effects of patient age, gender, and hospital teaching status on the use of these treatments were estimated using logistic regression models. RESULTS: Eligibility for treatment ranged from 68% (n=1627) for aspirin therapy, 38% (n=906) for lidocaine therapy, and 30% (n=734) for thrombolytic therapy to 19% (n=447) for beta-blocker therapy. Seventy-two percent of patients eligible to receive a thrombolytic agent received this therapy; 53% received beta-blockers; 81% received aspirin; and 88% received lidocaine. Among patients ineligible for lidocaine therapy (n=1503), 20% received this agent. Use of study drugs was lower among eligible elderly patients, especially those older than 74 years (thrombolytic agent: odds ratio, 0.2; 95% confidence interval, 0.1 to 0.4; aspirin: odds ratio, 0.4, 95% confidence interval, 0.3 to 0.6; beta-blocker: odds ratio, 0.4; 95% confidence interval, 0.2 to 0.8). Female gender was associated with lower levels of aspirin use among eligible patients (odds ratio, 0.7; 95% confidence interval, 0.6 to 0.9); and there was a trend toward lower levels of beta-blocker and thrombolytic use among eligible women. CONCLUSIONS: Use of lifesaving therapies for eligible patients with AMI is higher than previously reported, particularly for aspirin and thrombolytic use in nonelderly patients. Lidocaine is still used inappropriately in a substantial proportion of patients with AMI. Increased adherence to AMI treatment guidelines is required for elderly patients and women.

Adrenergic beta-Antagonists↗
PubMed1995

Coronary stenting for treatment of ostial stenoses of native coronary arteries or aortocoronary saphenous venous grafts.

This study examines the procedural success, complication, and restenosis rates in patients undergoing Palmaz-Schatz stenting of native coronary and saphenous vein graft ostial stenoses. All patients undergoing Palmaz-Schatz stent placement of ostial lesions (> or = 70% diameter stenosis within 3 mm from the arterial ostium) between November 1989 and February 1992 were included in this study. Patients were treated with aspirin dipyridamole, low molecular weight dextran, and heparin during the procedure and received systemic anticoagulation with warfarin for 1 month after the procedure. Angiographic measurements were obtained using electronic calipers. Coronary stents were placed in 41 ostial lesions of 41 patients. The target ostial stenosis was in a saphenous vein graft in 54% and a native coronary artery in 46% of lesions. The mean pre- and postprocedural minimal luminal diameters were 0.8 +/- 0.7 and 3.3 +/- 0.8 mm, respectively (p < 0.0001), corresponding to a mean diameter stenosis of 83.5 +/- 10.0% and 1.0 +/- 4.2%. Two patients had subacute stent thrombosis related to premature discontinuation of antithrombotic medications. Two patients died, 1 because of stent thrombosis and 1 because of progressive renal failure and sepsis. Angiographic follow-up was obtained at a mean of 5.8 +/- 1.8 months in 95% of patients with a successful stent procedure. The overall restenosis rate (> 50% diameter stenosis at follow-up) was 27.8%. Thus, stenting of ostial native coronary and vein graft stenoses can be performed with excellent angiographic and procedural success rates. Restenosis rates appear to be lower than expected using historical control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Functional equivalence of verbal and spatial information in serial short-term memory.

Performance on a test of serial memory for the spatial position of a sequence of dots showed similarities to typical results from the serial recall of verbal material: a marked increase in error with increasing list length, a modest rise in error as retention interval increased, and bow-shaped serial position curves. This task was susceptible to interference from both a spatial task (rote tapping) and a verbal task (mouthed articulatory suppression) and also from the presence of irrelevant speech. Effects were comparable to those found with a serial verbal task that was generally similar in demand characteristics to the spatial task. As a generalization, disruption of the serial recall of visuospatial material was more marked if the interference conditions involved a changing sequence of actions or materials, but not if a single event (tap, mouthed utterance, or sound) was repeated.

Humans↗
PubMed1995

The outcomes of elective laparoscopic and open cholecystectomies.

BACKGROUND: The demand for evidence of effectiveness for medical care has prompted the development of epidemiologic approaches to relating the outcomes of care to treatment. This study compares the outcomes of care for patients undergoing the newly introduced laparoscopic cholecystectomy with the results from conventional open cholecystectomies. METHODS: Consecutive cases of elective cholecystectomy from 35 hospitals (all of the metropolitan and selected rural hospitals in Minnesota) were enrolled in the study. Patients were interviewed on admission to establish baseline symptoms and functional status and to confirm risk factors. Their medical records were abstracted to yield information on risk factors, treatment, and hospital complications. To establish outcomes, patients were sent a questionnaire about their symptoms and functional status six months postoperatively. RESULTS: Of 3,448 patients studied, 2,490 (72 percent) had a laparoscopic procedure, including 195 cases that were converted to open cholecystectomies. Functional status data were obtained on 2,481 cases (76 percent). Laparoscopic operation was associated with more operative complications (odds ratio 3.02, p < 0.001), but with fewer general complications (odds ratio 0.32, p < 0.001). The mean time to return to work was 15 days for laparoscopic cases compared to 31 days for open procedures (p < 0.001). The only functional outcome difference between the two procedures was that patients who underwent laparoscopic cholecystectomies were more likely than those with conventional cholecystectomies to be able to perform their usual activities at follow-up evaluation (p < .001). There was evidence of a learning curve; the more laparoscopic procedures a surgeon performed, the fewer the operative (p < 0.01) and general (p < 0.0001) complications. There was no indication that the availability of laparoscopic operation was associated with more operations being performed. CONCLUSIONS: Laparoscopic operation seems to represent a significant advance in getting patients back to a normal life sooner. More attention needs to be given to which patients are most likely to benefit from cholecystectomy of either type. Epidemiologic approaches can be useful in assessing the effectiveness of care. Partnerships between providers and researchers can produce useful effectiveness data by supplementing available clinical records with more detailed outcome data.

Cholecystectomy↗
PubMed1994

Characteristics of visual interference with visuospatial working memory.

Recent discussions of visuospatial working memory have suggested that this subsystem may incorporate a visual buffer which holds visuospatial information relatively passively. Empirical investigations of visual interference with information held within a visuospatial subsystem have yielded somewhat equivocal results. Nonetheless, evidence from Logie (1986) has indicated that visuospatial processing can be disrupted by passive exposure to irrelevant visual material in a manner analogous to the disruption of serial verbal recall by exposure to irrelevant speech. This paper reports two experiments which explore whether such irrelevant visual input is disruptive to storage of imaginal information in a primarily spatial task--the Brooks spatial matrix task. Experiment 1 shows that exposure to irrelevant visual input during encoding selectively disrupts performance on a spatial, but not a verbal, version of the task. The extent of such disruption is shown to be independent of the visual complexity of the material, its similarity to the to-be-remembered information, or a change in state, with a static white square pattern yielding equivalent disruption to that produced by changing matrix patterns. The second experiment indicates that this pattern of effects is robust, and that such disruption is evident at an equivalent level when the visual material is present only during a 20-second retention interval. These results are interpreted as evidence of obligatory access of external visual material to a passive visual buffer. Implications for the nature of a visuospatial subsystem in working memory are discussed.

Adult↗
PubMed1993

Specialty differences in the 'July Phenomenon' for Twin Cities teaching hospitals.

This study evaluated changes over the academic year in the cost and the outcome of inpatient care to investigate the effect of housestaff experience in teaching hospitals. Patients with 25 preselected discharge diagnoses, admitted between January 1, 1983 and December 31, 1987 to acute-care, nonfederal, non-pediatric hospitals in the Minneapolis/St. Paul metropolitan area (total number available for analysis 240,467) were examined. Level of housestaff experience was measured as the number of days (1 to 365) into the academic year when the patient was admitted. Linear and logistic regression analyses were used to evaluate the different effects of experience on patient care in teaching hospitals compared with nonteaching hospitals. For the subset of patients with internal medicine diagnoses, the expected "July Phenomenon" was observed, with significant relative declines in diagnostic and pharmaceutical charges in teaching hospitals over the academic year. In contrast, surgery patients showed an increase in length of stay and various charges over the academic year in teaching hospitals. There were no meaningful effects of housestaff experience on mortality, operative complications, or nursing home discharge. These results indicate that housestaff training is significantly related to the use of hospital resources for inpatients, but that the degree and direction of the effects differ by specialty. These findings may reflect important differences among training programs in the process of physician education and its effects on patient care.

Bed Occupancy↗
PubMed1992

Irrelevant speech and serial recall: implications for theories of attention and working memory.

Irrelevant speech markedly impairs serial recall of visually presented lists, even though the person is asked to ignore the speech. In this, the first major review of the phenomenon, we conclude that (i) the effect occurs in memory rather than at encoding; (ii) within memory, the disruption occurs as a result of a confluence of information at the phonological rather than at the articulatory stage of coding; (iii) speech does not have privileged access to memory, since its disruptive effects may be attenuated by habituation; and (iv) disruption occurs as a result of the changing state of the auditory channel, not as had previously been thought the phonological similarity of visual and auditory streams, and is particularly sensitive to pitch changes in both speech and non-speech stimuli. These conclusions are discussed in the light of two complementary theoretical constructs: a cascading filter system responsible for the access of speech to memory and a system of coding within memory sensitive to changing state of the stream responsible for disruption of serial order. Recommendations are made also for empirical work to refine these constructs.

Attention↗
PubMed1991

Updating one's knowledge about the current status of vehicles in a freight system simulation.

The use of simulations of real-world settings can provide data relevant to ergonomics problems in a wide range of similar settings. This paper reports on a simulation of a freight service operation. It examines the effect of manipulating the type and format of information representation on the ability to update knowledge about the status of three vehicles. In addition, the effects of display type and the detection of violations of pre-learned rules on the ability to update are examined. The display format proved not to be a critical factor but the requirement to detect rule violations of a specific vehicle resulted in better memory-updating performance for that vehicle. The results are discussed in terms of a human memory mechanism, which is analogous to a computer operating system, involved in updating memory and detecting violations. Finally, the value of using this tool to examine complex cognitive processes relevant to the workplace is discussed.

Journal Article↗
PubMed1991

High speed rotational coronary atherectomy for patients with diffuse coronary artery disease.

High speed rotational coronary atherectomy was undertaken using the Rotablator in 42 patients who were suboptimal candidates for balloon angioplasty. Most patients (71%) had diffuse coronary artery disease, defined as a stenosis greater than 1 cm in length. Previous restenosis after balloon angioplasty was present in 21% and 10% had an ostial lesion. Adjunctive balloon angioplasty was not used to reduce residual stenosis after atherectomy. The procedure was successful in 76% of patients. Procedural success was achieved in 92% of patients with a lesion less than or equal to 1 cm in length, but in only 70% of patients with a lesion greater than 1 cm in length (p less than 0.01). One patient sustained abrupt closure of the target vessel, resulting in emergency bypass surgery and death. Small non-Q wave myocardial infarction occurred in eight patients (19%) and was associated with a longer lesion. The mean peak creatine kinase value in patients with non-Q wave myocardial infarction was 683 U/liter. Transient regional wall motion abnormalities were noted on the postatherectomy left ventricular angiogram in four of the eight patients with non-Q wave myocardial infarction. Follow-up angiography (at a mean interval of 6.2 +/- 2.6 months) was performed in 91% of patients and revealed restenosis (greater than 50% narrowing) in 59% The resistance rate was 22% for short lesions (less than or equal to 1 cm) and 75% for long lesions (greater than 1 cm) (p less than 0.05). In this study, the results of high speed rotational coronary atherectomy were strongly influenced by lesion length.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗