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Biomedical subjects

A Jackson

Publications and source records attributed to A Jackson.

At least 397 records · Page 22Linked to original sources
PubMedDate not supplied

Effects of lipofuscin on in situ hybridization in human neuronal tissue.

In situ hybridization is a highly sensitive technique for detecting nucleic acid sequences within tissues, and is frequently employed in neurovirology. However, this technique requires many appropriate controls in order to recognize and avoid potential artifactual hybridization. We have encountered abundant reaction to lipofuscin in neurons in human peripheral and central nervous systems, using various DNA probes, which could be misinterpreted as positive signals. This pseudohybridization reaction was resistant to treatment with RNase or DNase and was also present in tissue sections treated with hybridization mixture or nuclear autoradiographic emulsion in the absence of any radioactive probes. Characteristics used to distinguish between authentic in situ hybridization and the reaction to neuronal lipofuscin include cellular localization, color, margins and granular appearance, sensitivity to treatment with nucleases and the effect of exposure time on signal intensity. These guidelines should be used to avoid potential misinterpretation of in situ hybridization results with human tissue.

Adult↗
PubMedDate not supplied

Premature vascular calcification in a case of POEMS syndrome.

A patient with classical POEMS syndrome associated with a myeloproliferative disorder is presented, in whom extensive arterial calcification was seen at an early age in the absence of other predisposing factors. Radiographs also demonstrated several small discrete sclerotic foci elsewhere in the skeleton and areas of new bone formation around the spine which were described in previous cases. Histological studies in this patient demonstrated an osteosclerotic solitary plasmacytoma of bone and Castleman's disease of lymph nodes, both of which have previously been causally associated with POEMS syndrome. In addition, dermal infiltration by mast cells was demonstrated.

Adult↗
PubMedDate not supplied

The costal hook: an indicator of occult flail segment in chest trauma.

The presence of a hook-like configuration at the site of rib fracture reflects significant rotational displacement. Such displacement can occur only as the result of a further fracture at another site within the same rib and is therefore indicative of a flail segment injury even if a second fracture site is not clearly identified. This appearance is illustrated and termed the 'costal hook' sign.

Accidental Falls↗
PubMedDate not supplied

Endoscopic therapy for benign bile duct strictures.

Endoscopic therapy was attempted in 25 patients with benign strictures of the bile duct. In 23 patients, treatment involved endoscopic balloon dilation of the stricture zone or balloon dilation plus endoprosthesis placement. In 22 of 25 patients (88%), there was benefit from the endoscopic treatment. In 20 of 23 patients, there was significant radiographic improvement (p less than 0.001) in the diameter of their stricture following endoscopic therapy. All patients with elevated liver enzymes demonstrated rapid improvement following treatment. There was no significant morbidity or mortality associated with endoscopic treatment of benign biliary tract strictures. Follow-up study (mean, 4 +/- 0.3 years) discloses no recurrence of symptoms or elevated enzymes indicative of recurrent strictures. The treatment of benign bile duct strictures by a combination therapy of balloon dilation and stent placement provides a safe and effective treatment modality and an alternative to operative intervention.

Adolescent↗
PubMedDate not supplied

Exotic mice as models for aging research: polemic and prospectus.

Most gerontological research using rodent models employs inbred strains, or F1 hybrids derived from them, rather than populations of genetically heterogeneous individuals. This study presents the argument that reliance on genetically homogeneous rodents, though sanctioned by tradition, may not be ideal for many sorts of investigations, and that use of heterogeneous mice and rats would allow researchers to reach robust conclusions that were less likely to reflect strain-specific idiosyncrasies. Segregating stocks, bred by backcross, F2 cross, or four-way cross procedures, would be an improvement over inbred and F1 stocks, providing inexpensive, arbitrarily large, and reproducible populations of genetically diverse test subjects. These stocks would not, however, recapture allelic variations that are likely to have been lost when wild-trapped mice and rats are selected inadvertently over dozens of generations for breeding success in laboratory conditions. Development of specific pathogen free stocks from wild-trapped progenitors particularly from populations selected for relevant evolutionary history and physiological characteristics, may be of great value for analysis of aging and late-life pathophysiology.

Aging↗
PubMedDate not supplied

Population and biochemical genetics of the human mitochondrial malic enzyme.

The phenotypic variation of the mitochondrial malic enzyme (MEM) was examined in 121 brains and 46 heart tissue samples from the population of north-east England. There was no difference in gene frequency distribution between sexes and the two tissues. However, a significant variation has been observed in males compared with a Scottish study. The three common phenotypes of brain were partially purified on a DEAE Sephadex column. The kinetics, heat stability and dicumarol inhibition studies show no biochemical advantage for any of the phenotypes in human brain. The extensive polymorphism of MEM suggests a possible, yet unknown, selective factor for the spread of this polymorphism. With the existing evidence of regional and racial differences, the role of random genetic drift cannot be ruled out.

Brain↗
PubMedDate not supplied

Behavioral task-induced bronchodilation in asthma during active and passive tasks: a possible cholinergic link to psychologically induced airway changes.

This study investigated pulmonary and autonomic reactions to active and passive behavioral laboratory tasks among asthmatic subjects. It also examined the relationship between airway irritability, as measured by the methacholine challenge test (MCT), and autonomic activity and reactivity to these tasks. Fifty-one asthmatic and 37 nonasthmatic subjects were exposed to psychological laboratory tasks involving either active (mental arithmetic and reaction time) or passive (films depicting shop accidents and thoracic surgery) response. The MCT was given to asthmatics in a separate session. Active tasks reduced respiratory impedance, as measured by forced oscillation pneumography. They also increased heart rate and appeared to block vagal activity, as measured by respiratory sinus arrhythmia (RSA). Airway irritability as assessed by the MCT was positively related to amplitude of RSA and to skin conductance levels. Our data suggest that active and passive behavioral tasks may produce different pulmonary effects among both asthmatic and nonasthmatic individuals. Engaging in tasks requiring active responses may produce temporary improvements in pulmonary function. No autonomic differences were obtained between asthmatics and nonasthmatics in physiological response to stress, but greater cholinergic receptor sensitivity was suggested among high responders to methacholine.

Adolescent↗
PubMedDate not supplied

Probability of radiation-induced complications for normal tissues with parallel architecture subject to non-uniform irradiation.

A biologically based model is developed to predict radiation-induced normal tissue complication probability (NTCP) in inhomogeneously irradiated organs such as the lung or the kidney. The organ is assumed to be composed of independent functional subunits (FSUs) organized with a parallel architecture and it is assumed that the complication is produced only if a sufficiently large number of FSUs (the "functional reserve") are destroyed. A general expression for NTCP is derived, as well as simple expressions for the mean and standard deviation of the radiation damage to the FSUs. It is demonstrated that these results for inhomogeneous irradiation reproduce those of the serial and tumor control models when the functional reserve consists of one or all of the FSUs, respectively. When the number of FSUs is large, the dose response for organs with identical characteristics is very steep. Since clinical dose-response curves may arise from populations with varying functional reserves and radiosensitivities, we derive expressions for the NTCP for inhomogeneously irradiated organs that incorporate such variations.

Dose-Response Relationship, Radiation↗