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Biomedical subjects

W H Anderson

Publications and source records attributed to W H Anderson.

At least 55 records · Page 3Linked to original sources
PubMed1989

Cigarette smoking and federal black lung benefits in bituminous coal miners.

The records of 1000 consecutive coal miners applying for benefits under the Federal Coal Mine Health and Safety Act were examined to determine the contribution of age, dust accumulation, and cigarette smoking to the profile of the miner who satisfies the current pulmonary criteria for disability. Using the presence of pneumoconiosis on chest radiograph as the indication of significant coal dust accumulation, the miners were separated into Group A--those without pneumoconiosis (n = 316) and Group B--those with pneumoconiosis (n = 684). The federal spirometric criteria for disability identified 55/316 miners in Group A (14.5%) and 99/684 miners in Group B (17.4%) potentially eligible for an award (P = .27). The mean ages of miners in both groups did not differ significantly, nor was there difference in the mean ages of groups that did or did not meet the federal criteria. In both groups, those miners potentially eligible for a financial award smoked more cigarettes than did their counterparts (Group A, 31.0 v 18.5 pack-years, P less than .001; Group B, 31.3 v 23.6 pack-years, P less than .001). There was no difference in the smoking histories of the miners from either group who met the federal criteria. Our data indicate that, in the case of bituminous coal miners, the present federal legislation intended to identify and remunerate those who suffer lung impairment from chronic occupational exposure to coal dust is biased in favor of those who sustain additional damage to their ventilatory capacity by smoking cigarettes.

Coal↗
PubMed1988

Asymmetry of lysophosphatidylcholine/cholesterol vesicles is sensitive to cholesterol modulation.

Sonication of lysophosphatidylcholine (lysoPC; 20 mumol/mL) and cholesterol (chol) in aqueous medium produces lamellar structures over a wide range of concentrations. From 25 to 47 mol % cholesterol, electron microscopy (EM) after negative staining showed extended stacklike lamellae about 40 A thick. From 50 to 60 mol % chol, freeze-fracture EM showed homogeneous populations of small unilamellar vesicles averaging 260-310 A in diameter. Phosphorus-31 nuclear magnetic resonance was used to characterize the stacklike lamellae and to measure the distribution of the lysophospholipid between the outer and inner leaflet of the vesicles as a function of sterol concentration. We found that in lysoPC/chol dispersions containing less than equimolar amounts of cholesterol (25-47 mol %), the entire phosphorus signal (40.5 ppm) was shifted downfield by 10.5 ppm upon addition of Pr3+ (2.4 mM), consistent with the stacklike lamellar structures in which all lysoPC head groups are accessible to the ions. By contrast, addition of Pr3+ to lysoPC/chol vesicles containing equimolar or higher amounts of cholesterol (up to 60 mol %) gave rise to two phosphorus peaks. The more intense downfield signal (51.0 ppm) responsive to paramagnetic ions was assigned to lysoPC located in the outer vesicle leaflet. The upfield signal (40.5 ppm), which was not affected by the ions, was assigned to inside lysoPC. For lysoPC/chol (1:1) vesicles, an outside to inside lysophospholipid ratio (Ro/i) of 6.5 was determined. Essentially the same Ro/i value (6.7) was obtained on lysoPC/chol (1:1) vesicles which after dialysis contained only entrapped Pr3+.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholesterol↗
PubMed1988

Purine receptors and guinea-pig trachea: evidence for a direct action of ATP.

1. Adenosine (3-300 microM) and ATP (1-300 microM) each induced concentration-dependent relaxation of guinea-pig isolated tracheal preparations that had been precontracted with methacholine. 2. Ectonucleotidase enzymes on the trachea dephosphorylated ATP to form adenosine which was then further metabolised to inosine and hypoxanthine. 3. Dipyridamole (2 microM) inhibited the metabolism of adenosine but did not inhibit the dephosphorylation of ATP. Nevertheless dipyridamole potentiated the effects of both adenosine and ATP in relaxing tracheal smooth muscle. 4. Although adenosine 5'-[beta,gamma-imido] triphosphate (AMP-PNP), an analogue of ATP, was resistant to catabolism by ectonucleotidases, it was more potent at inducing relaxation than either ATP or adenosine, and was also potentiated by dipyridamole (2 microM). 5. Relaxations induced by ATP and by AMP-PNP were more rapid than those induced by adenosine. 6. We therefore conclude that the intact ATP molecule can itself induce relaxation of the guinea-pig trachea, without first having to be metabolised to adenosine, and furthermore that dipyridamole does not act simply by inhibiting the degradation (or uptake) of adenosine.

Adenosine↗
PubMed1988

Meperidine and normeperidine distribution in the rhesus monkey.

Previous work has shown that both meperidine and normeperidine are transferred across the placenta to the fetus. Little is known in primates, however, about the tissue deposition of these compounds. Four pregnant, dated rhesus monkeys within one week of term were anesthetized for cesarean delivery. An equal mixture of meperidine and normeperidine was administered as an intravenous bolus 10 minutes before delivery (1.25 mg/kg). The infants were then sacrificed at 20 minutes after birth and the concentration of the compounds in various organ systems were analyzed by gas-liquid chromatography and mass spectroscopy (GLC-MS). The infant serum 20 minutes after delivery revealed a meperidine concentration of 2.23 micrograms/ml and a normeperidine level of 0.67 micrograms/ml (3:1). In contrast, the tissues analyzed showed a much higher concentration of the metabolite in the liver (1:7), gallbladder (1:3), and brain (1:2). Other tissues, such as muscle and kidney, demonstrated equal levels of the two compounds. The authors conclude that normeperidine is quickly transferred to fetal tissues and to a greater degree than the parent compound in certain organs. The increased distribution, particularly in the brain, could account for the toxic actions in the cerebrum of the derivatives of meperidine.

Animals↗
PubMed1987

A digital radiology imaging system: description and clinical evaluation.

We have successfully interfaced an advanced microcomputer system to a 47-cm image intensifier for direct digital radiology. Our development effort has included the design and construction of hardware and the implementation of software. The system matrix (spatial resolution) is 1024 X 1024 and contrast resolution is 8 bits deep. A receiver-operator-characteristic analysis comparing conventional and digital laser chest radiographs for the detection of lung nodules demonstrated no statistical difference. Dosimetry measurements identified decreased patient dose. The intensifier-based digital imaging system is being increasingly used for a variety of examinations including IV pyelograms, all kinds of barium studies, and skeletal, trauma, and chest studies. Hard-copy laser-printed digital images with "bones black" are preferred by the radiology staff and have been well accepted by referring clinicians.

Evaluation Studies as Topic↗
PubMed1987

Platelet activating factor stimulates secretion of mucin by explants of rodent airways in organ culture.

Platelet activating factor (PAF; 1-o-alkyl-2-0-acetyl-sn-glycero-3-phosphocholine-3-phosphocholine) a potential mediator of anaphylaxis, stimulates secretion of mucin by explants of trachea from four separate rodent species (guinea pig, rat, rabbit, ferret) in organ culture. Enhanced secretion is not a result of cell damage or release of histamine by cells within the explants (e.g., platelets). It is inhibited by equimolar concentrations of the potent PAF-receptor antagonist, Ro 19-3704. PAF provokes production of immunoreactive peptidyl leukotrienes (ir-LTC4, LTD4, LTE4) within the explants. The stimulatory effect of PAF on mucin secretion is blocked by equimolar concentrations of nordihydroguiaretic acid (NDGA) a "mixed" inhibitor of both cyclo- and lipoxygenase pathways of arachidonic acid metabolism. Leukotrienes are localized within tracheobronchial epithelium by immunohistochemical staining, and physical removal of epithelium from explants inhibits production of leukotrienes in vitro under nonstimulated conditions and after exposure to PAF. In addition, the stimulatory effect of PAF on mucin secretion is not altered by FPL-55712, a receptor antagonist of LTD4. These results are consistent with the hypothesis that PAF stimulates secretion of mucin by activating biosynthesis of lipoxygenase products (e.g., peptidyl leukotrienes) within epithelial cells of the respiratory mucosa.

Animals↗
PubMed1987

Digital image-management networks: problems in implementation.

The apparent advantages of a DIMS are often cited by those involved in medical information-management research. The promise of a high-speed electronic image-management system that could increase a department's patient throughput and improve patient care is most attractive. Every major manufacturer of medical imaging equipment has a group working to develop such systems. Many problems remain to be solved before such systems can be acquired, installed, and made operational. This paper has summarized the significant technical problems yet to be solved.

Archives↗
PubMed1987

Variability in the evaluation of the Federal black lung benefits claimant.

A critical review of the medical data accumulated on 100 consecutive miners referred for evaluation for disability under the Federal Coal Mine Health and Safety Act documented the generation of an excess of unreliable data at an unacceptable cost, even though the evaluations had been performed by physicians who regularly perform this service. Physician training appears to have an impact on the accuracy and reproducibility of historical inquiry regarding items that would identify other causes of activity-limiting dyspnea. Physicians with pulmonary training are statistically more likely to include the cigarette smoking history, as well as history for the presence or absence of exertional chest pain and paroxysmal nocturnal dyspnea. Spirometric pulmonary functions that are supervised and interpreted by physicians with pulmonary training are less likely to show wide variation between the forced expiratory volume in 1 sec, and the direct maximum voluntary ventilation. Regardless of the source, the direct MVV measurement does not contribute additional useful information about a claimant's pulmonary impairment. Arterial blood gas analysis does not add to the discriminatory value of spirometry and should be dropped from the routine claimant's evaluation. Electrocardiography identifies cardiovascular disease in a sufficient number of applicants to make this test worthwhile. The presence or absence of pneumonconiosis on chest radiograph does not vary significantly when interpreted by the examining physician regardless of pulmonary training.(ABSTRACT TRUNCATED AT 250 WORDS)

Coal Mining↗
PubMed1986

Phase behavior of synthetic N-acylethanolamine phospholipids.

Both saturated and unsaturated N-acylethanolamine phospholipids form lamellar structures when dispersed in buffer. The addition of excess Ca2+ (Ca2+/N-acylphosphatidylethanolamine greater than 0.5) results in precipitation. Freeze-fracture replicas indicate that the addition of Ca2+ to the unsaturated lipid results in a non-bilayer structure while the Ca2+-complex of the saturated lipid is lamellar. Since unsaturated phosphatidylethanolamine (PE) is a non-bilayer lipid, its N-acylation with a saturated fatty acid converts a non-bilayer lipid into an acidic bilayer lipid capable of interacting with Ca2+ to return to a non-bilayer structure. Ca2+ may thereby exert an influence on membrane phenomena by regulating phase behavior within certain membrane domains. Differential scanning calorimetry (DSC) indicates that N-acylation of unsaturated PE with a saturated fatty acid also results in changes in thermotropic phase behavior. Therefore, N-acylation may affect fluidity within certain membrane domains.

Calcium↗
PubMed1986

Estimating digital information throughput rates for radiology networks. A model.

The design and implementation of a digital radiology image management system requires the definition, evaluation, and comparison of appropriate measures of system performance. The mean throughput rate is an important measure of the actual performance of a finished system. The mean throughput rate identifies the transmission of digital information either in bits/second or tasks/second. It is dependent on software, database management, equipment interface designs, number of users and display stations, and communications media. The mean throughput rate can document resource allocation bottlenecks within a given system. A model for estimating the mean throughput rate and its application in helping us design our radiology digital image networks is described.

Electronic Data Processing↗
PubMed1985

Brainstem and vermis atrophy in catatonia.

The computerized tomographic scans of five catatonic patients and five matched controls were blindly assessed. The catatonic patients showed preponderant atrophy of the brainstem and cerebellar vermis. Catatonia may be associated with lesions in these areas.

Aged↗
PubMed1984

The site of action of Ptychodiscus brevis toxin within the parasympathetic axonal sodium channel h gate in airway smooth muscle.

The red tide toxin produced by Ptychodiscus brevis ( PBTX ) may cause cough, sneezing, and asthma. Previous in vitro studies with isolated canine tracheal smooth muscle demonstrated that PBTX stimulates sodium channels of parasympathetic nerve endings and thus causes a contractile response. The present study investigated the mechanism of the PBTX effect on canine tracheal smooth muscle. Repeated exposure of the muscle strip to PBTX (final concentration 46 micrograms/ml) followed by washout of the toxin resulted in reestablishment of baseline tension but a failure of contraction on further addition of PBTX . However, veratridine and scorpion toxin (SCT), which are voltage-sensitive sodium channel activators, still induced contraction. Furthermore, the contraction caused by veratridine was enhanced by a high dose of PBTX , whereas contraction caused by SCT was not. Responses to veratridine and SCT as well as PBTX (previously reported) were blocked by tetrodotoxin (a sodium channel blocker), while acetylcholine responsiveness remained intact. These results indicate that PBTX receptors in parasympathetic nerves influence Na+ flux at the h gate, that these receptors differ from the veratridine and SCT receptors, and that the conformational change in the receptors induced by PBTX affects the tissue response to veratridine.

Animals↗