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Biomedical subjects

M Dickinson

Publications and source records attributed to M Dickinson.

31 records · Page 2Linked to original sources
PubMed1997

Small heat shock proteins and vasospasm in human umbilical artery smooth muscle.

Human umbilical artery smooth muscle is uniquely refractory to cyclic nucleotide-dependent vasorelaxation. Small heat shock proteins (HSPs) have been implicated as contractile regulatory proteins. Thus, we hypothesized that alterations in the phosphorylation of small HSPs may contribute to human umbilical artery smooth muscle vasospasm. Physiologic contractile responses were determined in a muscle bath and compared with phosphorylation events determined with whole-cell phosphorylation and 2-dimensional gel electrophoresis. Precontraction of bovine carotid artery smooth muscle with serotonin followed by relaxation with forskolin was associated with increases in the phosphorylation of HSP27 and HSP20. Precontraction of umbilical artery with serotonin followed by forskolin treatment led to increases in the phosphorylation of HSP27. However, the umbilical artery smooth muscle did not relax, nor was there an increase in the phosphorylation of HSP20 with forskolin treatment. These data suggest that impaired cyclic nucleotide-dependent relaxation of umbilical artery smooth muscle is associated with a lack of phosphorylation of HSP20.

Colforsin↗
PubMed1997

Relationship of tumor angiogenesis and nuclear p53 accumulation in invasive bladder cancer.

The purpose of this investigation was to evaluate the relationship between tumor angiogenesis and nuclear p53 accumulation in invasive bladder cancer. We studied 161 patients with invasive transitional cell carcinoma of the bladder who had previously undergone radical cystectomy. Analysis was performed to determine the presence of p53 nuclear accumulation and extent of tumor-associated angiogenesis. p53 status identified a group of patients at high risk for tumor progression (p53-altered tumors), and microvessel density determinations added additional prognostic information by identifying a subset of aggressive tumors within the wild-type p53 subgroup. At 5 years, patients with tumors exhibiting no evidence of p53 alterations and low microvessel counts demonstrated 3% recurrence and 88% survival, compared to 43% recurrence and 59% overall survival for patients with intermediate vessel counts and 61% recurrence and 43% overall survival for patients with the highest vessel counts (P < 0.001 and P = 0.003, respectively). Angiogenesis also provides additional prognostic information to patients with tumors that demonstrate p53 alterations. An association between angiogenesis and p53 status did exist (P = 0. 05); however, 27% of the tumors that showed no evidence of p53 alterations exhibited high microvessel counts, and 26% of tumors with evidence of p53 alterations had low microvessel counts. Tumor-associated angiogenesis adds additional useful prognostic information to that which is obtained from p53 status in patients with invasive transitional cell carcinoma of the bladder. Although an association between p53 status and the degree of angiogenesis was identified, other factors appear to play a role in the regulation of tumor-induced neovasularization.

Biomarkers, Tumor↗
PubMed1996

Type I A-kinase is activated by platelet-derived growth factor in mesangial cells.

In the glomerular mesangial cell, platelet-derived growth factor (PDGF) activates several signal transduction pathways. We examined the effect of PDGF on cAMP production and on cAMP-dependent protein kinase (A-kinase) activation. In mesangial cells, PDGF stimulated cAMP production in a dose- and time-dependent manner. This effect of PDGF was not prevented by pre-incubation with 50 microM indomethicin. PDGF also activated type I A-kinase, the predominate A-kinase isoform in mesangial cells, measured either by a decrease in A-kinase photoaffinity labeling with 8-azido-[32P]-cAMP, or by an increase in A-kinase substrate phosphorylation. The activation of A-kinase by PDGF is not dependent on the intermediate production of prostaglandins or cGMP. These data suggest that A-kinase participates in PDGF-induced signaling events in mesangial cells.

1-Methyl-3-isobutylxanthine↗
PubMed1996

Cell death in the CNS of the Wnt-1 mutant mouse.

Using the benzothiazolium-4-quinolium dye, TO-PRO-1, to detect cell death in live embryos, we labeled a developmental series of Wnt-1 null mutant and wild type embryos to determine if cell death contributed to the absence of the midbrain and rostral metencephalon observed in Wnt-1 mutant embryos. We found that there is no detectable cell death at early somite stages in Wnt-1 mutant embryos. However, we detected a significant, but transient, population of dying cells within the anterior dorsal metencephalon in 20-29 somite stage embryos. These cells located in the anterior dorsal metencephalon also stain positive using the TUNEL technique that utilizes terminal transferase to label DNA fragments that are typical in the nuclei of apoptotic cells. Thus, programmed cell death plays a role in the loss of the metencephalon, but apparently does not contribute to the earliest aspect of the mutant phenotype, namely the loss of the midbrain.

Animals↗
PubMed1996

Laparoscopic complications in markedly obese urologic patients (a multi-institutional review)

OBJECTIVES: Significant obesity is considered to be a relative contraindication to laparoscopic surgery. This study reviews the complications encountered in massively obese patients undergoing urologic laparoscopic surgery. METHODS: Body mass index (BMI) was used as an objective index to indicate massive obesity. Eleven institutions compiled retrospective data on 125 patients having a BMI greater than 30. Procedures performed included 76 pelvic lymph node dissections, 14 nephrectomies, 7 bladder neck suspensions, and 28 miscellaneous procedures. RESULTS: For the group as a whole, the mean BMI was 35.1 (range 30.1 to 57.2). Mean operative time was 202 minutes (range 60 to 480). Conversion to open surgery occurred in 15 of the 125 patients (12%). Complication rates (minor and major) were 22% (27 occurrences in 125 patients) intraoperatively and 26% (33 occurrences in 125 patients) postoperatively. The major complications included 2 trocar injuries to abdominal wall vessels, 1 bladder injury, 3 peripheral nerve injuries, 1 dysrhythmia, 1 deep vein thrombosis, 1 wound seroma, 1 nephrocutaneous fistula, 1 incisional hernia, and 1 death. CONCLUSIONS: In this review, complication rates for urologic laparoscopic surgery on massively obese patients were higher than in the general population undergoing laparoscopic surgery (0.3% to 21%).

Adolescent↗
PubMed1996

A one year prospective study of the effect of life events and medication in the aetiology of schizophrenic relapse.

BACKGROUND: We set out to determine whether and to what degree life events independent of illness increase the risk of relapse in schizophrenia following withdrawal from medication in the previous 6 months, either by triggering a relapse in the following 4 weeks or by acting cumulatively over time. METHOD: Seventy-one patients fulfilling DSM-III-R criteria for schizophrenia with chronic illness were followed for 48 weeks and assessed on the LEDS scale. Half were treated with regular neuroleptic medication and half had been recently withdrawn from medication. A subgroup was randomised double-blind to treatment or placebo. RESULTS: A proportional hazards regression model showed that life events made a significant cumulative contribution over time (P < 0.05) to the risks of relapse and that ceasing medication made an independent contribution. The risk of relapse increased in proportion to the number of life events but no interaction between medication status and events could be detected, i.e. life events were not more closely associated with relapse on medication than off medication. For those of the sample exposed to the mean rate of life events during the study period, it was estimated that 23% of the relapse risk could be attributed to life events, and for those with twice the mean rate of events, 41%. In contrast, patients who continued on regular medication had 80% less risk of relapse than those who had been withdrawn from medication either by choice or under double-blind controlled conditions. CONCLUSIONS: A contribution of life events to the risk of relapse in schizophrenia was confirmed by this study but the hypothesis that life events trigger relapse was not supported, nor was the hypothesis that life events are more relevant to relapse in patients on maintenance medication than in patients off medication.

Adult↗
PubMed1996

The efficacy of SNOMED, Read Codes, and UMLS in coding ambulatory family practice clinical records.

This study was initially developed as a traditional quantitative study to determine the level of match of identified clinical terms in three (3) clinical vocabularies. To address concerns raised by a review of the literature and our own experience, a supplemental study to collect qualitative data was added. Dictated progress notes from a stratified sample of patient visits over a period of four (4) years were used to obtain a representative sample of terms. A total of 144 progress notes were selected taking into consideration the usual demographics plus additional variables. From the 144 clinical notes, 864 terms were extracted and evaluated by level of match. The within-term effect was highly significant (F = 58.69, p < or = .001), indicating significant differences in the mean level of match for the three coding systems. Qualitative findings suggest that this and other published studies may not answer questions about the "efficacy of available clinical vocabularies in coding ambulatory family practice clinical records", and additional studies are needed which must be carefully structured and utilize a standardized procedure.

Family Practice↗
PubMed1994

Training for the use of the laryngeal mask in emergency and resuscitation situations.

It has been suggested that the laryngeal mask has a role to play in the management of the airway during resuscitation both from cardiac arrest and possibly major trauma. Should it be introduced for this purpose, there will be a need to provide training for a very large number of paramedical staff. Currently training in advanced airway management techniques involves live patient practice in theatres; clearly this system is already reaching a limit as paramedics in training often have some difficulty in reaching the prescribed number of procedures. This paper describes experience with a possible alternative utilising only classroom teaching.

Allied Health Personnel↗
PubMed1994

THE EFFECTS OF WING ROTATION ON UNSTEADY AERODYNAMIC PERFORMANCE AT LOW REYNOLDS NUMBERS

The downstroke-to-upstroke transition of many insects is characterized by rapid wing rotation. The aerodynamic consequences of these rapid changes in angle of attack have been investigated using a mechanical model dynamically scaled to the Reynolds number appropriate for the flight of small insects such as Drosophila. Several kinematic parameters of the wing flip were examined, including the speed and axis of rotation, as well as the duration and angle of attack during the wing stroke preceding rotation. Alteration of these kinematic parameters altered force generation during the subsequent stroke in a variety of ways. 1. When the rotational axis was close to the trailing edge, the model wing could capture vorticity generated during rotation and greatly increase aerodynamic performance. This vortex capture was most clearly manifested by the generation of lift at an angle of attack of 0&deg;. Lift at a 0&deg; angle of attack was also generated following rotation about the leading edge, but only if the downstroke angle was large enough to generate a von Karman street. The lift may be due to an alteration in the effective angle of attack caused by the inter-vortex stream in the downstroke wake. 2. The maximum lift attained (over all angles of attack) was substantially elevated if the wing translated backwards through a wake generated by the previous stroke. Transient lift coefficient values of nearly 4 were obtained when the wing translated back through a von Karman street generated at a 76.5&deg; angle of attack. This effect might also be explained by the influence of the inter-vortex stream, which contributes a small component to fluid velocity in the direction of translation. 3. The growth of lift with angle of attack was significantly elevated following a 7.5 chord stroke with a 76.5&deg; angle of attack, although it was relatively constant under all other kinematic conditions. 4. The results also indicate the discrepancies between transient and time-averaged measures of performance that arise when unsteady mechanisms are responsible for force generation. Although the influence of wing rotation was strong during the first few chords of translation, averaging the performance over as little as 6.5 chords of motion greatly attenuated the effects of rotation. 5. Together, these modeling results suggest that the unsteady mechanisms generated by simple wing flips could provide an important source for the production of aerodynamic forces in insect flight. Furthermore, the extreme sensitivity to small variations in almost all kinematic parameters could provide a foundation for understanding the aerodynamic mechanisms underlying active flight control.

Journal Article↗
PubMed1994

MODULATION OF NEGATIVE WORK OUTPUT FROM A STEERING MUSCLE OF THE BLOWFLY CALLIPHORA VICINA

Of the 17 muscles responsible for flight control in flies, only the first basalar muscle (b1) is known to fire an action potential each and every wing beat at a precise phase of the wing-beat period. The phase of action potentials in the b1 is shifted during turns, implicating the b1 in the control of aerodynamic yaw torque. We used the work loop technique to quantify the effects of phase modulation on the mechanical output of the b1 of the blowfly Calliphora vicina. During cyclic length oscillations at 10 and 50 Hz, the magnitude of positive work output by the b1 was similar to that measured previously from other insect muscles. However, when tested at wing-beat frequency (150 Hz), the net work performed in each cycle was negative. The twitch kinetics of the b1 suggest that negative work output reflects intrinsic specializations of the b1 muscle. Our results suggest that, in addition to a possible role as a passive elastic element, the phase-sensitivity of its mechanical properties may endow the b1 with the capacity to modulate wing-beat kinematics during turning maneuvers.

Journal Article↗
PubMed1988

The diagnostic dilemma of myxedema and madness, axis I and axis II: a longitudinal case report.

A patient with presumed chronic paranoid schizophrenia had chronic thyroiditis and Grade I hypothyroidism. Psychosis cleared following treatment with thyroid replacement. The probable presence of two axis II disorders may have contributed to the missed medical diagnosis and the patient's eventual suicide. The personality disorders were a major problem in the patient's medical and psychiatric care. The differential diagnosis among hypothyroidism and primary axis I psychotic and depressive psychopathology has always been problematic. When axis II pathology is also present, the diagnostic dilemma is increased.

Adult↗
PubMed1986

False positive indirect fluorescent antibody (IFA) tests for antibody to herpes simplex virus 1. Comparison of four commercially available methods.

Four commercially available herpes simplex virus 1 (HSV-1) indirect fluorescent antibody (IFA) kits were compared with the use of sera selected because they were negative for HSV antibody by complement fixation (CF less than 1:8) and by ELISA (less than 1:100). However, 14 of 24 (58.3%) of these HSV-1 antibody-negative sera were positive at greater than or equal to 1:10 with the use of the HSV-1 IFA kit from Electronucleonics, 15 of 24 (62.5%) were positive with the Clinical Sciences HSV-1 IFA kit, 4 of 24 (16.7%) were positive with Zeus Scientific, and 4 of 18 (22.2%) were positive with the Gull Laboratories product. HSV-1 induces Fc receptors that commonly cause false positive IFA tests for HSV antibody. Therefore, further studies were undertaken to determine whether Fc receptors accounted for these false positive results. Staphylococcal protein A (SPA) is known to bind to the Fc portion of human IgG and therefore could be used to distinguish between the binding of an antibody by its Fab or its Fc portion. Thus, when fluorescein isothiocyanate conjugated (FITC) SPA was used as conjugate instead of FITC antibody to human IgG, true HSV-1 antibody-containing sera remained positive, but the false positives identified in the commercial IFA kits did not. The authors conclude that HSV-1-induced Fc receptors are responsible for most of the problem of these false positives and that HSV-1 serology probably should not be done by this type of IFA method until this problem is corrected.

Antibodies, Viral↗