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Biomedical subjects

B Peterson

Publications and source records attributed to B Peterson.

At least 19 recordsLinked to original sources
PubMed1995

Behavioral laterality in individuals with Gilles de la Tourette's syndrome and basal ganglia alterations: a preliminary report.

This study aims to investigate whether abnormalities in structural basal ganglia asymmetries in Tourette's syndrome (GTS) have functional significance. Eleven adult GTS patients and 11 normal controls who had participated in the previous MRI study where GTS patients lacked the normal left-greater-than-right (L > R) lenticular asymmetry were re-recruited. They were administered a battery of lateralizing neuropsychological tasks believed to require intact basal ganglia function. GTS subjects lacked normal functional asymmetries on these measures, as predicted. The neuropsychological measures also accounted for a significant portion of the variance in the severity of tic symptoms. These findings suggest that GTS subjects who lack normal basal ganglia structural asymmetries also lack normal functional asymmetries on related neuropsychological measures.

Adult↗
PubMed1995

Structure and internal consistency of a shoulder model.

A three-dimensional biomechanical model of the shoulder is developed for force predictions in 46 shoulder structures. The model is directed towards the analysis of static working situations where the load is low or moderate. Arbitrary static arm postures in the natural shoulder range may be considered, as well as different kinds of external loads including different force and moment directions. The model can predict internal forces for the shoulder muscles, for the glenohumeral, the acromioclavicular and the sternoclavicular joint as well as for the coracohumeral ligament. A solution to the statistically indeterminate force system is obtained by minimising an objective function. The default function chosen for this is the sum of the squared muscle stresses, but other objective functions may be used as well. The structure of the model is described and its ingredients discussed. The internal consistency of the model, its structural stability and the compatibility of the elements that go into it, is investigated.

Acromioclavicular Joint↗
PubMed1995

Functional significance of individual variations in callosal area.

We considered the hypothesis that the richness of callosal interhemispheric connections has a role in determining the degree of behavioural laterality and time-sharing ability in dual-task performance. Behavioural laterality as measured by dichotic word listening, line bisection and turning bias tests correlated inversely with the midsagittal cross-sectional area of the corpus callosum, as seen on MRI. The amount of dual task interference was strongly inversely correlated with the callosal area in both within-hemisphere and between-hemispheres conditions. These relationships between normal variations in callosal area, and outcomes on tests both of laterally and time-sharing capacity in normal adults suggest that the corpus callosum assumes a cross-excitatory role when subjects perform these tasks.

Adult↗
PubMed1995

Placement of umbilical venous catheters with use of bedside real-time ultrasonography.

Real-time ultrasonography was used to assess the position of umbilical venous catheters tips in 79 newborn infants (birth weight range, 400 to 4200 gm). The position of the umbilical venous catheters determined by ultrasonography was compared with the projection of the catheter tip on the closest vertebral body shown on a standard chest radiograph. Of the catheters initially placed with radiographic guidance, 56% were repositioned because of unsatisfactory location. Ultrasonography is more precise than radiography because it allows direct visualization of the catheter tips in relation to internal vascular structures. When ultrasonography is unavailable, placement at the ninth thoracic vertebral body ensures safe positioning.

Catheterization↗
PubMed1995

Voluntary redistribution of muscle activity in human shoulder muscles.

Four shoulder muscles (the supraspinatus, the infraspinatus, the anterior and middle portion of the deltoid, and the descending part of the trapezius) were examined with electromyography in abducted arm positions. By using feedback techniques, we found that the subjects could reduce the EMG activity voluntarily by 22-47% in the trapezius muscle while keeping different static postures. This was not true for any other muscle investigated. When the trapezius activity was reduced there was a tendency towards an increase of EMG activity in some other shoulder muscles, particularly the infraspinatus. The findings may be related to relaxation from an initial overstabilization of the shoulder, or redistribution of load among synergists. It is suggested that the possibility of reducing trapezius activity may be of ergonomic significance. It is also noted that EMG trapezius activity may not serve as a universal descriptor of total muscular load in the shoulder.

Adult↗
PubMed1995

Recombinant alpha-2b-interferon in therapy of previously untreated hairy cell leukemia: long-term follow-up results of study by Cancer and Leukemia Group B.

In 1985, Cancer and Leukemia Group B initiated a multi-institutional study to define the role of interferon alpha in therapy of previously untreated active hairy cell leukemia (HCL). This is a long-term follow-up report of the study. Fifty-five evaluable patients were treated with recombinant interferon-2b 2 million units/m2 subcutaneously three times a week for 1 year. Treatment was well tolerated; toxicity mainly consisted of flu-like syndrome and pancytopenia, both of a transient nature. Seventy-three percent of patients had objective beneficial responses with 8.3 months median time to achieve at least a partial response (PR). After 1 year of therapy, the patients have been observed for a median of 5 years. There was a continual trend towards relapse throughout this period but 28% have remained in remission beyond 6 years. Forty-six patients (83%) are alive at 6 years. Among the 40 patients who achieved at least a PR, there were 28 with splenomegaly at the beginning of study: the spleen size was reduced in all with interferon alpha therapy and none required splenectomy. This study confirms the results of other investigators, and demonstrates that recombinant alpha interferon-2b is an effective agent for treatment of hairy cell leukemia.

Adult↗
PubMed1994

Immunoglobulins and IgG subclasses in children following severe head injury.

OBJECTIVE: To study immunoglobulin production after severe blunt head trauma in children. DESIGN: Serum for IgG, IgM, IgA, IgE, and IgG subclasses were drawn from 10 children admitted with severe head injury (ISS 31.2, GCS 5.4) on day 1, 7, 14 and 21 after injury. RESULTS: 5 of the 10 patients developed infection between 7 and 14 days and 2 died of complications of pneumonia. On day 1, IgM levels averaged 95.6% of the mean of the age-specific normal controls. By day 7, IgM levels averaged 383% (p < 0.01). While all patients were within the age-specific normal range (+/- 2 SD) on day 1, 7 of 10 patients were above the normal range by day 7. There was no difference in IgM levels between infected and non-infected patients. Five patients were below the age-specific normal range for IgG on day 1, with 3 still low on day 7. By day 21, IgG levels averaged 141% of the mean of the age-specific normal controls. IgG subclasses followed a pattern similar to total IgG levels. Marked increases in IgE were seen in 3 patients. CONCLUSIONS: IgM levels increased dramatically in all patients within seven days of the injury. While 50% of these children had a deficit of IgG in the first week, total IgG and IgA levels increased after injury, but not as rapidly as IgM levels. Unlike pediatric burn patients, there is no persistent hypogammaglobulinemia following severe blunt trauma in children.

Adolescent↗
PubMed1994

Carboplatin in previously treated multiple myeloma. A Cancer and Leukemia Group B phase II trial.

Carboplatin 400 mg/m2 per month was evaluated as a single agent in 15 patients with multiple myeloma who had had one prior chemotherapy regimen. All but three were judged to have had some degree of refractoriness to prior therapy. Hematologic toxicity was frequent and sometimes severe. There were no responses. Further evaluation of standard-dose single-agent carboplatin in refractory myeloma does not appear warranted.

Aged↗
PubMed1994

A rapid preadmission method for predicting inpatient course of disease for patients with HIV-related Pneumocystis carinii pneumonia.

Pneumocystis carinii pneumonia (PCP) has been the most common reason for hospitalization and the most common cause of death for persons with HIV infection. Hospital mortality rates for PCP range from 10 to 60%. Studies that evaluate differences in hospital mortality rates must control for differences in patient severity of illness. We developed a simple staging system for categorizing severity of illness in patients with PCP. We analyzed the relation between clinical factors and in-hospital mortality for 576 hospitalized patients with HIV-related PCP treated at 56 hospitals for the years 1987 to 1990. Four stages of PCP could be identified based on three routinely measured clinical variables: alveolar-arterial oxygen difference, total lymphocyte count, and body mass index. The mortality rate increased by stage: 1% for Stage 1, 8% for Stage 2, 23% for Stage 3, and 48% for Stage 4. The four-stage severity system compared well with previous models developed for AIDS and for PCP, and is easier to use in clinical practice. Our staging system identifies patients with a high and low risk of in-hospital death upon admission. Physicians may benefit from consideration of PCP stage in deciding on management strategies. In addition, researchers involved in clinical trials of new agents for PCP might consider stratification by PCP stage in order to define homogenous groups.

AIDS-Related Opportunistic Infections↗
PubMed1993

Phenotypic markers and BCL-1 gene rearrangements in B-cell chronic lymphocytic leukemia: a Cancer and Leukemia Group B study.

The markers, CD11b, CD11c, CD14, CD21, CD23, CD25, CD38, and FMC7 were correlated with morphologic and other laboratory and clinical characteristics of 127 patients with untreated CD5+ chronic lymphocytic leukemia (CLL). Only CD38 and CD21 were significantly associated with atypical CLL morphology. The integrin associated markers CD11b and CD11c were associated with lower leukocyte count (white blood cell count [WBC]) and lower Rai stage. By contrast, the activation antigen CD23 was associated with a higher WBC, higher Rai stage, younger age group, and the presence of lymphadenopathy. Therefore, we conclude that CD23 positivity may reflect a more aggressive form of CLL, and CD11b and CD11c positivity a less aggressive form. The BCL-1 gene rearrangement was present in 5 of 84 (6%) CLL cases examined and was associated with atypical morphology and surface expression of CD11b. Patients with a BCL-1 gene rearrangement may represent a CLL subset or possibly a different B-cell disease.

Adult↗
PubMed1993

Hodgkin disease in patients 60 years of age or older. Histologic and clinical features of advanced-stage disease. The Cancer and Leukemia Group B.

BACKGROUND: This article reviews the salient pathologic and clinical features of 171 patients with Stage III-IV disease who were 60 years of age or older who were treated on four Hodgkin disease (HD) protocols from 1969 to 1988. METHODS: Pretherapy sections were reviewed centrally for correlation of the histologic classification with anatomic sites of involvement and survival. RESULTS: The diagnosis of HD was confirmed in 114 (66.7%) patients. Non-Hodgkin lymphomas (NHL) and a miscellaneous non-HD group accounted for 52 (30.4%) and 5 (2.9%) of the cases. The overall median survival times of patients with Stage III-IV HD and NHL who were 60 years of age or older in the four protocols were not significantly different (1.5 versus 1.3 years, respectively; P = 0.28). There also was no significant correlation between the survival of these patients with HD and either the Rye classification, 19 specific histologic parameters, or the British National Lymphoma Investigation grading system for HDNS. In the last protocol, the 5-year survival rate of patients with HD who were 60 years of age or older was lower than that of patients 40-59 years of age or that of those younger than 40 years of age (31% versus 63% versus 79%, respectively, P < 0.0001). Patients with HD entered into the two most recent protocols showed lower incidences of involvement of cervical and iliac-inguinal-femoral lymph nodes and skin-subcutaneous tissues than the patients with NHL who were misdiagnosed as HD. Moreover, patients with Stage III-IV HD in the most recent protocol who were 60 years of age or older had lower rates of involvement of the cervical and mediastinal-hilar lymph nodes and a higher rate of involvement of the gastrointestinal tract than younger patients. CONCLUSIONS: Patients with Stage III-IV HD and NHL who are 60 years of age or older differ with respect to the rates of involvement of specific anatomic sites but not in survival when treated with HD protocols. In contrast, patients of different age groups with Stage III-IV HD disease differ with regard to the rates of involvement of anatomic sites and survival.

Age Factors↗
PubMed1993

Sample size requirements and length of study for testing interaction in a 2 x k factorial design when time-to-failure is the outcome [corrected].

This paper provides equations for calculating the sample size necessary to test an interaction effect in an 2 x k factorial design when time-to-failure is the outcome of interest. The results are a direct extension of those used by George and Desu and Makuch and Simon who provide sample size requirements for comparing two and k treatment groups, respectively. Duration of a clinical trial concerned with an interaction is calculated using the results of Rubinstein, Gail, and Santner. The results in the present paper can also be used to investigate the impact that an unforeseen interaction has on the power to detect a treatment main effect. This impact can be substantial, even for moderate interactions.

Aspirin↗
PubMed1993

A multiple drug intoxication involving cyclobenzaprine and ibuprofen.

A 19-year-old black man presented to the emergency room with superficial cuts on the anterior wrists, lethargy, tachycardia, and metabolic acidosis. Multiple containers of medication were found at the scene. Dysrhythmias developed and the patient died 7 h after admission. No anatomic cause of death was identifiable at autopsy. Toxicologic analysis identified the following drugs in the blood (mg/L): cyclobenzaprine (0.3), phenylpropanolamine (2.5), chlorpheniramine (0.2), lidocaine (6.6), phenytoin (19), and ibuprofen (130). Lidocaine and phenytoin had been administered therapeutically. The major symptoms displayed by the patient were tachycardia and metabolic acidosis, symptoms consistent with cyclobenzaprine and ibuprofen intoxication, respectively. Therefore, the medical examiner ruled that the cause of death was multiple drug intoxication and that the manner of death was suicide.

Adult↗
PubMed1993

Reduced basal ganglia volumes in Tourette's syndrome using three-dimensional reconstruction techniques from magnetic resonance images.

Using a 1.5-tesla GE Signa MR scanner, we imaged the brains of 14 right-handed Tourette's syndrome (TS) patients (11 men, three women), aged 18 to 49 years, who had minimal lifetime neuroleptic exposure. We also studied an equal number of normal controls individually matched for age, sex, and handedness and group-matched for socioeconomic status. We circumscribed basal ganglia on sequential axial images from spin-echo proton density-weighted acquisitions (TR 1,700, TE 20; slice thickness, 3 mm with 1.5-mm skip) and submitted the images for three-dimensional processing at a computer graphics workstation. Our hypothesis of lenticular nucleus volume reduction in TS was confirmed for the left- but not the right-sided nucleus. Post hoc analyses revealed smaller mean volumes of the caudate, lenticular, and globus pallidus nuclei compared with controls on both the right and left. Further analyses of basal ganglia asymmetry indices suggest that TS basal ganglia do not have the volumetric asymmetry (left greater than right) seen in normal controls. These findings confirm and extend prior phenomenologic, neuropathologic, and neuroradiologic studies that implicate the basal ganglia in the pathogenesis of TS.

Adult↗
PubMed1992

Towards a model for force predictions in the human shoulder.

In this paper the concept of a three-dimensional biomechanical model of the human shoulder is introduced. This model is used to analyze static load sharing between the muscles, the bones and the ligaments. The model consists of all shoulder structures, which means that different positions and different load situations may be analyzed using the same model. Solutions can be found for the complete range of shoulder motion. However, this article focuses only on elevation in the scapular plane and on forces in structures attached to the humerus. The intention is to expand the model in future studies to also involve the forces acting on the other shoulder bones: the scapula and the clavicle. The musculoskeletal forces in the shoulder complex are predicted utilizing the optimization technique with the sum of squared muscle stresses as an objective function. Numerical results predict that among the muscles crossing the glenohumeral joint parts of the deltoideus, the infraspinatus, the supraspinatus, the subscapularis, the pectoralis major, the coracobrachialis and the biceps are the muscles most activated during this sort of abduction. Muscle-force levels reached values of 150 N when the hand load was 1 kg. The results from the model seem to be qualitatively accurate, but it is concluded that in the future development of the model the direction of the contact force in the glenohumeral joint must be constrained.

Arm↗