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Biomedical subjects

B Johnson

Publications and source records attributed to B Johnson.

At least 19 recordsLinked to original sources
PubMed2007

Dissociated representations of irritation and valence in human primary olfactory cortex.

Irritation and negative valence are closely associated in perception. However, these perceptual aspects can be dissociated in olfaction where irritation can accompany both pleasant and unpleasant odorants. Whereas the sensation of odor reflects transduction at olfactory receptors, irritation reflects concurrent transduction of the odorant at trigeminal receptors. Thus a stimulus can be either a pure olfactant activating the olfactory receptors only or a bimodal odorant activating both types of receptors. Using event-related functional magnetic resonance imaging and a 2 x 2 experimental design contrasting odorant valence (pleasant/unpleasant) and odorant type (pure olfactant/bimodal) we found activity in piriform cortex to be associated with valence, and not type, of odors. In contrast, activity in the olfactory tubercle was associated with type, and not valence, of odors. Importantly, this was found when perceived intensity was held equal across odorants. These findings suggest that dissociable neural substrates subserve the encoding of irritation and valence in olfaction.

Adult↗
PubMed2006

Uncoated quartz resonator as a universal biosensor.

We studied dynamic processes in drying drops of model protein-salt solutions, using an uncoated quartz resonator as a biosensor. To measure these processes we developed a method based on recording the dynamics of the Acoustic-Mechanical Impedance (AMI) of a drop as it dried on the surface of a quartz resonator oscillating at a resonant frequency of 60 kHz. The aim of this work was to highlight the role of some components of serum in self-organization processes. Human serum albumin (HSA), fibronectin (Fn), immunoglobulin G (IgG), immunoglobulin M (IgM), bovine serum albumin (BSA), sodium chloride (NaCl), Potassium Chloride (KCl), and nonionic surfactant O(CH(2)CH(2))(n)CH(2)CH(2)OH were used as components of the tested solutions. It was shown that dynamics of the AMI in drying drops were closely related to liquid composition. This approach allowed us to distinguish with good accuracy solutions in which one or more components (proteins or salts) were replaced by other components with the same mass concentration. We assumed that these differences were due to different surface properties and native functions of proteins, and different positions of salts in the Hofmeister line. Our preliminary work demonstrated that the dynamics of phase transitions in drying drops of serum could be used as an informative parameter for medical diagnostics. In this study, we highlight some positions in this cause-effect chain.

Biosensing Techniques↗
PubMed2006

A phase 2 study of high-activity 186Re-HEDP with autologous peripheral blood stem cell transplant in progressive hormone-refractory prostate cancer metastatic to bone.

PURPOSE: We investigated the potential for improvement in disease control by use of autologous peripheral blood stem cell transplant (PBSCT) to permit administration of high activities of (186)Re-hydroxyethylidene diphosphonate (HEDP) in patients with progressive hormone-refractory prostate cancer (HRPC). METHODS: Eligible patients had progressive HRPC metastatic to bone, good performance status and minimal soft tissue disease. Patients received 5,000 MBq of (186)Re-HEDP i.v., followed 14 days later by PBSCT. Response was assessed using PSA, survival, pain scores and quality of life. RESULTS: Thirty-eight patients with a median age of 67 years (range 50-77) and a median PSA of 57 ng/ml (range 4-3,628) received a median activity of 4,978 MBq (186)Re-HEDP (range 4,770-5,100 MBq). The most serious toxicity was short-lived grade 3 thrombocytopenia in 8 (21%) patients. The median survival of the group is 21 months (95%CI 18-24 months) with Kaplan-Meier estimated 1- and 2-year survival rates of 83% and 40% respectively. Thirty-one patients (81%, 95% CI 66-90%) had stable or reduced PSA levels 3 months post therapy while 11 (29%, 95% CI 15-49%) had PSA reductions of >50% lasting >4 weeks. Quality of life measures were stable or improved in 27 (66%) at 3 months. CONCLUSION: We have shown that it is feasible and safe to deliver high-activity radioisotope therapy with PBSCT to men with metastatic HRPC. Response rates and survival data are encouraging; however, further research is needed to define optimal role of this treatment approach.

Aged↗
PubMed2006

Camel tuberculosis--a case report.

An adult male dromedary bull was diagnosed with pulmonary tuberculosis (Tb). The dromedary was severely emaciated and died 2 months after the onset of the disease. It exhibited typical Tb lesions in both lungs and lung lymph nodes. A guinea pig inoculated with lung tissue from theTb camel died after 3 weeks from typical Tb. Mycobacteria were isolated from the dromedary's lung and lung lymph nodes and also from different organs of the guinea pig. The microorganism was identified as member of the antelope clade of the Mycobacterium tuberculosis complex.

Animals↗
PubMed2006

Service users and other stakeholders' evaluation of a liaison mental health service in an accident and emergency department and a general hospital setting.

Liaison mental health care has been an emerging specialism of mental health nursing in the UK since the early 1990s. Studies have so far looked only briefly at service user evaluation. A qualitative study involving 47 interviews with service user and professional stakeholders was undertaken to determine what is important to stakeholders in a liaison mental health-care service. The largest group of stakeholders interviewed were service users. Analysis of the data was undertaken using the service user interviews to guide the development of themes. The majority of the issues identified were raised by both service users and professionals. The three key themes were, the practicalities of the service including waiting time, the staffing profile and receiving the service, which included issues such as the opportunity to talk and outcomes. The findings provide new information regarding what service users and other stakeholders expect from a liaison mental health service and important areas to consider when offering a satisfactory service.

Attitude of Health Personnel↗
PubMed2006

Voriconazole prophylaxis in lung transplant recipients.

Lung transplant recipients have one of the highest rates of invasive aspergillosis (IA) in solid organ transplantation. We used a single center, nonrandomized, retrospective, sequential study design to evaluate fungal infection rates in lung transplant recipients who were managed with either universal prophylaxis with voriconazole (n = 65) or targeted prophylaxis (n = 30) with itraconazole +/- inhaled amphotericin in patients at high risk (pre- or posttransplant Aspergillus colonization [except Aspergillus niger]). The rate of IA at 1 year was better in lung transplant recipients receiving voriconazole prophylaxis as compared to the cohort managed with targeted prophylaxis (1.5% vs. 23%; p = 0.001). Twenty-nine percent of cases in the targeted prophylaxis group were in patients colonized with A. niger who did not receive itraconazole. A three-fold or higher increase in liver enzymes was noted in 37-60% of patients receiving voriconazole prophylaxis as compared to 15-41% of patients in the targeted prophylaxis cohort. Fourteen percent in the voriconazole group as compared to 8% in the targeted prophylaxis group had to discontinue antifungal medications due to side effects. Voriconazole prophylaxis can be used in preventing IA in lung transplant recipients. Regular monitoring of liver enzymes and serum concentrations of calcineurin inhibitors are required to avoid hepatotoxicity and nephrotoxicity.

Antifungal Agents↗
PubMed2006

Predation as a cause of neurologic signs and acute mortality in a pheasant flock.

A flock of approximately 15,000 ring-necked pheasants (Phasianus colchicus) was evaluated for a sudden increase in mortality and acute neurological signs after having been previously diagnosed 3 wk earlier with a chronic respiratory disease of undetermined etiology. Approximately 25 live birds were displaying neurological signs including circling, ataxia, and obtunded behavior and 50 birds were dead. Three birds with neurological signs were submitted for evaluation. Extensive subcutaneous hemorrhage over the head and penetrating puncture wounds through the skull and into the brain were found. Trauma from a wild predatory mammal, most likely the long-tailed weasel (Mustela frenata) that had invaded the pheasant house and expressed surplus killing behavior was determined to be the cause of the acute neurological signs and mortality. The relationship of the chronic respiratory disease to the predation episode was not determined but it is possible that pheasants with severe respiratory disease may have had increased susceptibility to predation.

Animals↗
PubMed2005

C4d deposition in lung allografts is associated with circulating anti-HLA alloantibody.

UNLABELLED: The complement activation demonstrated by vascular C4d deposition is used to diagnose antibody-mediated rejection (AMR) in renal allografts, but remains controversial in lung transplantation (LTX). METHODS: C4d deposition was assessed by immunohistochemistry in 192 lung transplant biopsies from 32 patients. ELISA analysis was performed on 415 serum samples in those 32 temporally and rejection-grade matched LTX patients; 16 patients developed HLA-Ab, while the other 16 patients remained negative. The specificity of C4d staining was further compared in 18 additional LTX patients without HLA-Ab or acute cellular rejection (ACR), but in the presence of CMV-pneumonitis or reperfusion injury. RESULTS: Specific subendothelial C4d deposition was seen in 5 of 16 (31%) patients with HLA-Ab and was absent in 16 patients without HLA-Ab (p<0.05). All patients with specific C4d deposition exhibited donor-specific HLA-Ab. There were 13 patients with bronchiolitis obliterans syndrome in the group of 16 HLA-Ab positive patients, versus 2/16 in ELISA-negative patients (p<0.005). One of 7 patients with CMV pneumonitis and 2 of 11 patients with reperfusion injury also showed C4d positivity (not statistically significant). CONCLUSIONS: In this study, specific subendothelial C4d deposition was a marker for the involvement of HLA-Ab in lung allograft rejection. The patchy nature, low sensitivity, and specificity of C4d staining might limit clinical use in protocol biopsies. However, in patients with decreasing pulmonary function, refractory ACR and/or HLA-Ab, specific C4d deposition may serve as a marker of coexistent AMR.

Acute Disease↗
PubMed2005

Infrared spectroscopy analysis of the structure of multilayer Langmuir-Blodgett films: effect of deposition velocity and pH.

Multiple Langmuir-Blodgett (LB) films of arachidic acid were deposited on germanium (Ge) substrates from subphase solutions of 10(-4) M CdCl2 at different pH values and at different deposition speeds. Attenuated total reflectance infrared (ATR-IR) spectroscopy was used to obtain information on the molecular order and structure of these multilayer LB films. At pHs higher than the pKa of the fatty acid/cation system, transfers took place only during the downstroke, indicating X-type deposition. At pH = pKa and large deposition speeds, deposition partially failed during the downstroke, resulting in Z-type depositions. Analysis of the infrared spectra indicates that multiple LB films deposited only during the upstroke (Z-type) or during downstrokes (X-type) have a centrosymmetric structure typical of films deposited during the upstroke and downstroke, except for a slight decrease in molecular order and tilt angle as the pH increases (X-type). The centrosymmetric structure indicates that rearrangement of layers takes place between cycles. Experimental evidence of such rearrangement occurring in a fatty acid/divalent cation salt subphase is shown here, and rearrangement alternatives are discussed.

Journal Article↗
PubMed2005

The surgical correction of protuberant ears.

While prominent ears are considered a sign of good fortune in the Far East, Western society looks upon prominent ears in a far less positive manner. Children with prominent ears are often the subjects of verbal and at times physical abuse by their peers, resulting in adverse psychological effects. Advances in otoplasty have made it possible not only to pin back the ears, but also to reshape them, reduce their size, or make them more symmetrical. For a dermatologic surgeon, an otoplasty may be an unfamiliar surgical procedure, however, the surgery itself does not significantly differ from ear wedges or cartilage removal procedures for skin cancer, procedures with which the dermatologic surgeon is quite familiar.

Ear, External↗
PubMed2004

First results from the Cryogenic Dark Matter Search in the Soudan Underground Laboratory.

We report the first results from a search for weakly interacting massive particles (WIMPs) in the Cryogenic Dark Matter Search experiment at the Soudan Underground Laboratory. Four Ge and two Si detectors were operated for 52.6 live days, providing 19.4 kg d of Ge net exposure after cuts for recoil energies between 10 and 100 keV. A blind analysis was performed using only calibration data to define the energy threshold and selection criteria for nuclear-recoil candidates. Using the standard dark-matter halo and nuclear-physics WIMP model, these data set the world's lowest exclusion limits on the coherent WIMP-nucleon scalar cross section for all WIMP masses above 15 GeV/c2, ruling out a significant range of neutralino supersymmetric models. The minimum of this limit curve at the 90% C.L. is 4 x 10(-43) cm2 at a WIMP mass of 60 GeV/c2.

Journal Article↗
PubMed2004

[Fall risk factors and fall injuries in hospitalized elderly patients].

Fall Risk Factors have been analysed (RAI-MDS-System) in a population of patients, who were hospitalised between 1995 and 2000 in a geriatric department of a community hospital. In multivariate analysis, viseral-problems, incontinence and depression were fall-protective factors, whereas problems with transfer, the use of assistive walking-aids, female gender and age were fall risk-factors. No independent contribution to the fall-risk was delivered by memory-impairment, problems in decision-making, low body-mass-index, the use of more than three medications and the use of restraints. Fall injuries were analysed in a patient population (n = 218), that was hospitalized in the year 2001 in the geriatric department of a community hospital after a fall. The analysis showed an enormous heterogenicity of the injury-patterns: 58.7% of the fall-patients suffered from a fracture, 10.6% of them had more than one fracture, 34% suffered from other injuries. 77 surgical interventions were performed. The mean length of stay of the fall-patients was 4.5 days higher than the mean of all geriatric patients.

Accidental Falls↗
PubMed2004

The value of abdominal examination in the diagnosis of abdominal aortic aneurysm.

BACKGROUND: There is considerable variability in the reported value of clinical examination in the diagnosis of abdominal aortic aneurysms (AAA). This study aims to assess accuracy of abdominal examination by a doctor, a nurse and the patient in the diagnosis of AAA and whether this accuracy is related to the size of the aneurysm and/or the BMI of the patient. METHODS: 164 patients, 138 men and 26 women, median age 71 years, consented to participate in this prospective, single blind, controlled study. Thirty-nine patients attending for carotid duplex were used as controls. Abdominal examination was performed by a doctor and a nurse. Patients then performed self-examination. RESULTS: Examination by a doctor, a nurse and the patient were similar in accuracy in diagnosing/excluding AAA which was directly related to AAA size and patient BMI. The Negative Predicted Value of abdominal examination exceeds 0.9 with AAA diameters > or =4 cm and the Positive Predictive Value exceeds 0.8 with AAA diameters > or =5 cm. CONCLUSIONS: Abdominal examination by a doctor, a nurse and the patient is of value in the exclusion and diagnosis of significant AAA. It should be promoted and may represent a useful adjunct to population screening with ultrasound.

Aged↗
PubMed2004

Speed choice by drivers: the issue of driving too slowly.

Quite correctly, the majority of road safety speeding initiatives focus on drivers travelling at excessive speeds. This study, however, focused on the potential problem of driving too slowly. Six thousand, four hundred and eighty vehicles from around the Perth metropolitan area in Western Australia had their speeds recorded; observations were also made of these vehicles to identify characteristics of the driver and vehicle. In addition, a community survey with 240 members of the public was conducted to examine their attitudes towards slow drivers. As expected, results showed that older drivers drove more slowly than the other age brackets, women drove more slowly than men, and that heavily laden vehicles drove more slowly than other types of vehicles. Additionally, the slowest days were weekdays and the quickest were Saturdays. Community attitudes, generally mirrored the observational findings, and indicated that the public believed that slow driving was sometimes a safety problem causing some accidents. These data are discussed, and some possible countermeasures are briefly introduced to address the problem.

Accidents, Traffic↗
PubMed2002

The use of multidisciplinary assessment and scientific measurement in advanced juvenile idiopathic arthritis can categorise gait deviations to guide treatment.

BACKGROUND: It is difficult to identify the range of gait deviations associated with juvenile idiopathic arthritis (JIA) using simple clinical observations. AIMS: To use objective gait analysis to accurately describe biomechanical gait abnormalities in JIA and to search for common patterns, which may subsequently serve as a basis for therapeutic intervention. METHODS: Children with persistent polyarticular arthritis and symmetrical joint involvement were referred to the Gait Analysis Laboratory and independently assessed by a multidisciplinary team. Gait analysis was performed using an in-house Visual Vector System and the Novel PEDAR in-shoe plantar pressure measurement system. Clinical groupings were based on the extent of joint restriction: minimal (group A), and moderate-severe (with supinatory foot deformity (group B), or with pronatory foot deformity (group C)). Gait analysis enabled classification of each subject into one of four gait patterns: either near normal (pattern I) or one of three adaptive patterns defined by the predominant abnormality--lower limb pain (pattern II), lower limb deformity (pattern III), or a combination of pain and deformity of the lower limb (pattern IV). RESULTS: Of the 15 subjects assessed as part of this study, seven were placed into clinical group A, six into group B, and two into group C. All the subjects with gait patterns I and II were found in clinical group A. Both subjects from clinical group C exhibited gait pattern III. All subjects from clinical group B and the remainder from group A exhibited a mixture of gait patterns III and IV. CONCLUSION: Despite the initial clinical observations it was not always possible to predict the resultant gait pattern. Scientific gait analysis allowed a clear distinction to be made between primary and secondary gait deviations, and accurate targeting of physiotherapy and orthotic interventions to suit each individual. Prospective quantitative analysis in a larger sample is under way to support the clinical effectiveness of these findings.

Adaptation, Physiological↗
PubMed2002

Lung and heart-lung transplantation at the University of Pittsburgh: 1982-2002.

The University of Pittsburgh lung transplantation program began in 1982 and through 2002 we have performed 576 lung and 101 heart-lung transplants. One-, 3- and 5-year survival rates over the past decade have been 77%, 62% and 55%, respectively, comparing favorably to ISHLT registry outcomes of 73%, 57% and 46%. We continue to utilize a very thorough evaluation process but have been flexible and aggressive with potential recipients with regard to age, coronary artery disease and disease state (eg., scleroderma). Despite worldwide progress in the field of lung transplantation, many difficulties remain. The limited number of lungs deemed acceptable for transplantation continues to hinder application to a greater number of patients. Our efforts in this regard have focused on cooperation with our OPO in education and detailed donor management protocols. Chronic rejection also remains a major difficulty frequently leading to death. Recent work utilizing aerosol cyclosporine in patients with established chronic rejection suggests that this therapy may prolong life. We are also hopeful that recently initiated therapies utilizing T-cell induction strategies may contribute to further improvement in outcomes.

Brain Death↗