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Biomedical subjects

W B Johnson

Publications and source records attributed to W B Johnson.

At least 37 records · Page 2Linked to original sources
PubMed1995

Respiratory syncytial virus--associated lower respiratory diseases in hospitalised pre-school children in Ibadan.

An analysis of the features of lower respiratory diseases (LRD) associated with Respiratory Syncytial Virus (RSV) in 21 children aged 1-23 months, indicated that the clinical features did not differ appreciably from those described for LRD due to other infective agents. It was however, remarkable that none of the children was grossly malnourished, neither was there any death. The final respiratory diagnoses were bronchiolitis alone (6 cases), bronchopneumonia (6 cases), empyema/pleural effusion (3 cases, including one with bronchopneumonia), lobar pneumonia (3 cases, including one with associated bronchopneumonia). Streptococcus pneumonia and Klebsiella pneumoniae respectively, were isolated from blood culture in the two cases with lobar pneumonia alone. One child had laryngotracheobronchitis (croup) alone and another, croup associated with bronchiolitis and bronchopneumonia. Radiologically, the single most common lesion was patchy consolidation (8 cases) followed by hyper-inflation (6 cases); in one case, there was no observable lesion on the chest radiograph. All the 6 children who had bronchiolitis alone were aged 12 months and below, and were well nourished; conversely, 8 of the 12 children with pneumonia alone or in addition to other lesions and both children with pleural effusion, were older than 12 months and underweight. Other viral agents were identified in 8 (38%) of the cases. Complications included heart failure in 4 cases and a combination of anaemia and heart failure in one child with empyema. In a child with symptom complex and radiological features suggestive of acute obstructive lower respiratory infection with immunofluorescence evidence of RSV infection, age and nutritional status are important factors in determining the need for antibiotic therapy pending the outcome of bacterial cultures.

Age Distribution↗
PubMed1995

Narcissistic personality as a mediating variable in manifestations of post-traumatic stress disorder.

This case report serves to highlight the manner in which premorbid narcissistic personality adjustment may exacerbate the clinical expression of post-traumatic stress disorder (PTSD). Narcissistic personality may enhance vulnerability to distress at lower levels of trauma. In addition, narcissistic needs for esteem may produce atypical presentations of PTSD. The case history of a patient with both narcissistic personality disorder and PTSD is presented as a means of illustrating this phenomenon.

Humans↗
PubMed1994

Synaptotrophic effects of human amyloid beta protein precursors in the cortex of transgenic mice.

The amyloid precursor protein (APP) is involved in Alzheimer's disease (AD) because its degradation products accumulate abnormally in AD brains and APP mutations are associated with early onset AD. However, its role in health and disease appears to be complex, with different APP derivatives showing either neurotoxic or neurotrophic effects in vitro. To elucidate the effects APP has on the brain in vivo, cDNAs encoding different forms of human APP (hAPP) were placed downstream of the neuron-specific enolase (NSE) promoter. In multiple lines of NSE-hAPP transgenic mice neuronal overexpression of hAPP was accompanied by an increase in the number of synaptophysin immunoreactive (SYN-IR) presynaptic terminals and in the expression of the growth-associated marker GAP-43. In lines expressing moderate levels of hAPP751 or hAPP695, this effect was more prominent in homozygous than in heterozygous transgenic mice. In contrast, a line with several-fold higher levels of hAPP695 expression showed less increase in SYN-IR presynaptic terminals per amount of hAPP expressed than the lower expressor lines and a decrease in synaptotrophic effects in homozygous compared with heterozygous offspring. Transgenic mice (2-24 months of age) showed no evidence for amyloid deposits or neurodegeneration. These findings suggest that APP may be important for the formation/maintenance of synapses in vivo and that its synaptotrophic effects may be critically dependent on the expression levels of different APP isoforms. Alterations in APP expression, processing or function could contribute to the synaptic pathology seen in AD.

Amyloid beta-Protein Precursor↗
PubMed1994

Acute lower respiratory infections in hospitalised urban pre-school Nigerian children: a clinical overview.

One hundred and three hospitalised urban pre-school Nigerian children aged 2 weeks to 4 years with various acute lower respiratory tract infection (ALRI), were studied prospectively over a 9- month period (August 1985 - April 1986). Overlapping seasonal peaks, corresponding to the rainy/early harmattan months of August through November were most noticeable for the two major viral ALRI syndromes namely, bronchiolitis and croup. The overall M:F ratio was 1.1:1, but a corresponding ratio of 1.6:1 was recorded in the infants. The commonest ALRI symptoms were cough, breathlessness and fever while chest wall retraction, nasal flaring, tachypnoea and auscultatory crepitations were the most frequently recognised physical findings. Grunting respiration was recognised in 26 patients, majority of whom had pleural effusion and/or severe bronchopneumonia. Bronchopneumonia was the single commonest ALRI diagnosis, recorded alone or in combination with another lower respiratory syndrome, in 64 (61.2%) of the 103 cases. The croup:bronchiolitis: pneumonia ratio was 1:2.3:8.3. Nasopharyngitis was recorded in 42 (40.7%) of cases, and was frequently associated with the presumably viral ALRI syndromes of croup and bronchiolitis. Pleural effusion, frequently purulent, was the commonest respiratory complication, while heart failure and anaemia were the most frequently recognised associated conditions, found predominantly in patients with pneumonia and bronchiolitis. There was an overall ALRI case-fatality of 7.8%, representing 8 deaths, in 3 of whom measles was a co-morbid condition. All the 8 deaths had a final diagnosis of pneumonia with or without other ALRI syndromes/associated complications. While subjects with complicating pleural effusion recorded the longest mean duration of hospitalisation, those with bronchiolitis had the shortest duration of hospitalisation and no death. The epidemiologic, as well as the diagnostic and therapeutic implications of our observations are discussed.

Acute Disease↗
PubMed1994

Psychiatric stigma in the military.

There is potential for the stigma of mental health care to directly affect an active duty member's career. The authors are aware of cases in which fear of adverse career consequences has led service members to avoid needed mental health care. In order to investigate the legitimacy of this fear, the authors surveyed 252 USN and USMC commanding and executive officers concerning their attitudes about service members who had received mental health and other services; 138 responded. Overall the responses were neutral and there were relatively few negative evaluations of service members who had received services. Military health care providers should take an active role in diminishing the stigma of mental illness, and in allaying fears of adverse career consequences for seeking care.

Adult↗
PubMed1992

Modification of Brassica seed oil by antisense expression of a stearoyl-acyl carrier protein desaturase gene.

Molecular gene transfer techniques have been used to engineer the fatty acid composition of Brassica rapa and Brassica napus (canola) oil. Stearoyl-acyl carrier protein (stearoyl-ACP) desaturase (EC 1.14.99.6) catalyzes the first desaturation step in seed oil biosynthesis, converting stearoyl-ACP to oleoyl-ACP. Seed-specific antisense gene constructs of B. rapa stearoyl-ACP desaturase were used to reduce the protein concentration and enzyme activity of stearoyl-ACP desaturase in developing rapeseed embryos during storage lipid biosynthesis. The resulting transgenic plants showed dramatically increased stearate levels in the seeds. A continuous distribution of stearate levels from 2% to 40% was observed in seeds of a transgenic B. napus plant, illustrating the potential to engineer specialized seed oil compositions.

Base Sequence↗
PubMed1992

Host factors and acute lower respiratory infections in pre-school children.

The relationship between certain host-related variables and the short-term outcome of hospitalization for severe acute lower respiratory infections was studied prospectively in a cohort of 103 pre-school Nigerian children. The respective mean ages of those with bronchiolitis and croup were 3.2 months and 18.9 months while the corresponding M:F ratios were 2.5:1 and 1:1. It was highly significant that all the eight children that died were malnourished (P less than 0.01). Furthermore, malnourished subjects with pleural effusion, in whom bacteraemia was common, stayed longest in hospital while subjects with bronchiolitis and croup, in whom malnutrition was distinctly uncommon, had the shortest duration of admission. Multiple microbial identifications and bacteraemia were common in malnourished subjects with ALRI. Mortality was significantly higher in older children (P less than 0.05), but sex, immunization/breast-feeding status and co-existing measles or pertussis, were individually neither related to the admission outcome nor the duration. It is concluded that malnutrition is a strong predictor of ALRI-related death in the pre-school child. The significance of bacteraemia and multiple microbial identifications in malnourished children, and the ARI-control implications of the study are discussed.

Acute Disease↗
PubMed1988

Increased vascular resistance due to a reduction in red cell deformability in the isolated hind limb of swine.

This study investigated whether red cells with reduced deformability impeded flow through the microcirculation. Red cells were made less deformable in their normal biconcave disc shape by incubation with 2% formaldehyde (fRBCs). The blood supply to the right hind limb was isolated in 26 swine and the femoral artery was instrumented with two fine catheters, a flow probe, and an inflatable occluder. Flow was measured over a range of different perfusion pressures during adenosine-induced vasodilation under control conditions (C) and during an infusion of fRBCs at 1 ml/kg per minute (not to exceed 20 ml) into the femoral artery. At the same perfusion pressure (P), flow was significantly reduced 5 min after the fRBC infusion: Flow at P = 20 mm Hg, C = 41 ml/min vs fRBC = 10 ml/min; at P = 40, C = 160 ml/min vs fRBC = 79 ml/min; and at P = 60, C = 278 ml/min vs fRBC = 147 ml/min, with P less than 0.02 for all comparisons. Flow was still significantly reduced 15 min after the fRBCs, but by 30 min, it had returned to the control value. Chromium-51-labeling of red cells revealed that about one-third of fRBCs was trapped in the microcirculation compared to less than 3% of normal cells. This reduction in flow with fRBC infusion was not altered by alpha blockade, indicating that adrenergically mediated spasm was not responsible for the reduced flow. Aspirin 35 mg/kg iv completely prevented the reduction in flow despite an absence of change in the percentage of fRBCs trapped. Thus, red cells with reduced deformability infused into the circulation caused a significant, but transient, reduction in flow. The reduction in flow was not primarily related to entrapment of the abnormal RBCs, but may be mediated through platelet aggregation or release of potent vasoconstrictor substances from platelets or endothelial cells.

Adenosine↗
PubMed1988

Clinical technique for the removal of root canal obstructions.

A technique was described that allows root canal obstructions to be exposed, secured, and removed. This technique suggests limited and careful use of a cyanoacrylate adhesive to bond a sized, hollow tube to the exposed tip of an obstruction. This method has been used clinically and has been found efficient and effective. It allows root canal obstructions to be removed without further breakage, while avoiding unnecessary mutilation of tooth structure.

Cyanoacrylates↗
PubMed1988

No reflow and extent of infarction during maximal vasodilation in the porcine heart.

To explore the relation between myocardial and vascular injury in the generation of the no-reflow phenomenon, the pressure-flow relation during maximal vasodilation after coronary artery reperfusion was studied in the open-chest porcine model. During both endogenous and maximal vasodilation with intracoronary adenosine, pressure-flow (P/Q) plots were constructed before and after 20-minute (n = 9) or 40-minute (n = 17) circumflex artery occlusions. Decreases in circumflex vascular bed conductance were represented by downward shifts in P/Q plot regression lines. No significant change occurred in P/Q line slope or pressure at zero flow 30 minutes after release of the 20-minute occlusion, and no infarction was found. After release of the 40-minute occlusion, a small but insignificant decrease in P/Q line slope occurred during endogenous vasodilation. However, during maximal vasodilation, a significant (p less than 0.01) decrease in P/Q line slope was present during reperfusion compared with preocclusion corresponding to a decrease in vasodilatory reserve (P/Q line slope = 1.52 +/- 0.14 ml/min/mm Hg preocclusion vs. 1.03 +/- 0.13 at 15 minutes reperfusion). Pretreatment with aspirin did not prevent this decrease in vascular conductance during maximal vasodilation. Total circumflex, as well as subendocardial, midmyocardial, and subepicardial blood flows, was measured with radioactive microspheres. There was a good correlation between the extent of infarction measured by triphenyltetrazolium chloride staining and the decrease in vascular conductance during maximal vasodilation for all three myocardial layers as well as for the total circumflex vascular bed. Hence, the degree of no-reflow correlates closely with the extent of infarction during maximal vasodilation (but not during endogenous vasodilation) and is not altered by aspirin therapy.

Animals↗
PubMed1985

Incomplete coronary vasodilation during myocardial ischemia in swine.

To determine if endogenous (ENDG) vasodilation was maximum during myocardial ischemia, left anterior descending (LAD) mean pressure (P) was reduced for 20 min in 13 swine. At LAD P of 45 mmHg (LAD P45) flow fell during ENDG = 25 but rose to 44 ml/min during adenosine (AD) infusion (P less than 0.01). Flow increased to subendocardium (ENDG 0.65 vs. AD 1.04 ml X min-1 X g-1) and to subepicardium (ENDG 0.99 vs. AD 1.83 ml X min-1 X g-1; P less than 0.05). No significant change occurred in myocardial O2 consumption (MVO2; ENDG 2.91 vs. AD 3.18 ml X min-1 X g-1), lactate extraction (ENDG = -5 vs. AD-1%), and wall thickening (WTh; ENDG + 16 vs. AD + 17%). At LAD P35, flow during ENDG was 12 but rose to 19 ml/min during AD (P less than 0.01). Flow increased to subendocardium (ENDG 0.24 vs. AD 0.46 ml X min-1 X g-1; P less than 0.02) and subepicardium (ENDG 0.51 vs. AD 0.87 ml X min-1 X g-1; P less than 0.01). No significant change occurred in MVo2 (ENDG 1.38 vs. AD 1.59 ml/min), lactate extraction (ENDG -38 vs. AD -22%), WTh (ENDG -1 vs. AD + 1%). Thus endogenous vasodilation reserve was not used fully during ischemia. AD increased flow but did not improve abnormalities in myocardial function or metabolism.

Adenosine↗
PubMed1983

Phenazopyridine-induced hemolytic anemia.

An elderly man was seen with hemolytic anemia due to the urinary tract analgesic, phenazopyridine hydrochloride. The mechanisms underlying this toxic reaction are presented. Cautious use of this drug in elderly patients and in those with renal insufficiency is emphasized.

Aged↗
PubMed1983

Study of radon daughter concentrations in Polk and Hillsborough counties.

The present study finds the average excess dose equivalent resulting from external gamma radiation on reclaimed land to be 17 mrem/yr (whole body); the highest excess is 166 mrem/yr, well below the NCRP limit that might be compared (500 mrem/yr). In contrast, the annual average excess exposure from radon-daughter inhalation on reclaimed land has been found to be 540 mrem/yr to the whole lung, more than twice that resulting from natural background in the study area and more than 5 times the national average dose equivalent reported in NCRP 45 (100 mrem/yr). Moreover, a significant number of individuals presently receive lung doses exceeding limits inferred from NCRP recommendations. These results indicate the need for corrective action to reduce radiation exposure of members of the general population whose exposure exceeds dose limiting recommendations and possibly to reduce radiation exposures well below these limits, thereby lowering risks even further.

Florida↗
PubMed1980

Transport and fate of gaseous pollutants associated with the National Energy Program.

The experimental evidence related to the long-range transport and transformations of sulfates has been critically reviewed. It has been concluded that sulfate emissions from various sources can be superimposed on each other during long-range transport to create episodes far from the contributing sources. Sulfates are important contributors to degrading visibility through the United States including relatively pristine areas in the western United States. Acid sulfate components, along with nitric acid, may increase the problem of acidity in precipitation on soils, vegetation, and lakes in certain areas of the eastern United States. Improvements in monitoring of these pollutants are required to follow changes in air quality caused by long-range transport.

Air Pollutants↗