Measuring the distribution of trace elements amongst dissolved colloidal species as a fingerprint for the contribution of tributaries to large boreal rivers.

Organic and inorganic colloids play important roles governing the speciation, transport, and bioaccessibility of trace elements in aquatic systems. These carriers are especially important in the boreal zone, where rivers that contain high concentrations of iron and organic matter are prevalent. The distribution of trace elements amongst different colloidal species (or "speciation profile") can therefore be useful as a fingerprint to detect different trace element sources and for tracking colloid transformations, with implications for bioaccessibility. Asymmetrical flow field-flow fractionation coupled to an inductively coupled plasma mass spectrometer was applied to detect the source of trace elements based on their speciation profile along a 125-km stretch of a large river in the Canadian boreal forest. Both the concentration and proportion of bound trace elements were increased by tributary inputs: bound As, Co, Fe, Mn, Pb, U, and Zn increased monotonically from upstream to downstream, increasingly resembling the speciation profile of tributaries. Principal component (PC) analysis also revealed tributary contributions of bound Cu, Ni, Th, V, and Y reflecting their higher concentrations in tributaries, and PC scores also increased monotonically from upstream-downstream. Monotonically decreasing concentrations of mainly ionic and small (i.e.

Vagal reflexes referred from the upper aerodigestive tract: an infrequently recognized cause of common cardiorespiratory responses.

OBJECTIVE: To review the physiologic basis for normal and abnormal vagal reflexes arising from the pharynx, larynx, and esophagus, as well as the relevance of vagal reflexes to the pathogenesis of such clinically common cardiorespiratory responses as bradycardia, tachycardia, dysrhythmia, coronary angiospasm, bronchospasm, laryngospasm, prolonged apnea, and singultus (hiccups). DATA SOURCES: Pertinent articles and reviews were identified through a MEDLINE search (April 1966 to October 1991). Older studies and others not identified in the MEDLINE search were found through a manual search of the bibliographies of the retrieved articles. STUDY SELECTION: Experimental studies in both humans and animals, as well as case series and single case reports, were selected for evaluation and citation. In instances where a similar phenomenon was described in multiple independent reports, only studies that provided a novel finding or interpretation were cited. More authoritative book chapters and peer-reviewed summaries were also cited in support of commonly accepted principles. DATA EXTRACTION AND SYNTHESIS: Most of the clinical data are derived from case reports and small case series and are therefore anecdotal; equal weight was given to all such studies. Reports of conflicting observations or interpretations were clearly identified and were cited without exception. CONCLUSIONS: Stimulation of the upper aerodigestive tract can lead to clinically significant cardiorespiratory responses. Although the prevalence of and risk factors for such responses have not been established, we suggest that a pharyngeal, a laryngeal, or an esophageal source for abnormal cardiorespiratory responses be sought whenever a detailed clinical evaluation fails to reveal a cause, particularly when there are concurrent symptoms or signs of upper aerodigestive tract disease, such as dysphagia or gastroesophageal reflux.

Swallowing dysfunction in the postpolio syndrome: a cinefluorographic study.

Twenty patients with a remote history of poliomyelitis and recent or progressive dysphagia were evaluated with cinefluorography. Radiographic abnormalities were present in the pharynx in varying degrees in all but one of the patients. Findings included atrophy of the prevertebral soft tissues, unilateral or bilateral weakness of the tongue or soft palate, paresis or paralysis of the pharyngeal constrictor muscle, incomplete or absent epiglottic tilt, poor laryngeal elevation, poor laryngeal closure with laryngeal penetration, aspiration (often without a cough), and luminal narrowing at the cricopharyngeal level. Other structural lesions included a Zenker diverticulum in one patient, bilateral pharyngeal pouches in five, and a unilateral pouch in one. Additional structural lesions contributing to dysphagia were found in two other patients, including a focal stricture in the cervical esophagus in one patient and two stenotic rings in the distal esophagus in another. In four patients (one of whom had the Zenker diverticulum), the inferior constrictor muscle contracted forcibly above a prominent cricopharyngeus muscle, perhaps contributing to the formation of the diverticulum. It is important to examine postpolio patients with dysphagia carefully with dynamic imaging to assess the severity of decompensation and to detect other lesions that may be treatable. The information derived can be used to guide management.

Psychogenic dysphagia and globus: reevaluation of 23 patients.

Despite warnings against attributing dysphagia to psychological causes, the diagnoses of "psychogenic dysphagia" or "globus hystericus" have been previously applied to 13% of patients referred to the Johns Hopkins Swallowing Center. This paper reports the results of reevaluation of 23 patients previously diagnosed as having symptoms of psychogenic origin. The Swallowing Center evaluation documented an explanation for symptoms in 15 (65%). No cause of dysphagia could be documented in eight patients. All five patients with the "globus sensation" had a documentable abnormality of swallowing. Overall, nine patients had esophageal pathology, while six had pharyngeal disease. Five had structural lesions constricting the lumen, while 10 had motor dysfunction of either the pharynx or esophagus. Review of the referral records of these patients indicates the quality of prior evaluation for patients previously labeled as having a swallowing disorder of psychogenic origin is variable, and that once attribution of symptoms to psychogenic causes is made, the diagnosis is rarely reconsidered. We conclude that attribution of the diagnosis of psychogenic dysphagia should be made with caution, and only after thorough evaluation. Any change or progression of symptoms should prompt a careful re-evaluation.

How I do it: examination of the patient with dysphagia.

Difficulty in swallowing is not an uncommon symptom. Approximately 10,000 persons choke to death every year in the United States, and at least 50% of patients in nursing homes have some difficulty eating or drinking. Dysphagia will become an increasing problem as the population continues to age, as more intensive resuscitative measures are applied, and as more aggressive head and neck surgery is performed. The practicing radiologist should be familiar with the examination technique and interpretation of swallowing studies.

Examination of the patient with dysphagia.

Difficulty in swallowing is not an uncommon symptom. Approximately 10,000 persons choke to death every year in the United States, and at least 50% of patients in nursing homes have some difficulty eating or drinking. Dysphagia will become an increasing problem as the population continues to age, as more intensive resuscitative measures are applied, and as more aggressive head and neck surgery is performed. The practicing radiologist should be familiar with the examination technique and interpretation of swallowing studies.

Lines of the pharynx.

This superbly illustrated article is an invaluable guide to the interpretation of double contrast pharyngograms.

Radiologic evaluation of swallowing.

Diagnostic imaging procedures are useful to analyze the complex mechanism of swallowing. They may be employed beneficially to answer specific questions of swallow coordination, and to distinguish between various forms of airway penetration. The pathophysiology of upper and lower airway involvement may be determined and visualized.

Anatomy and physiology of the pharynx.

Radiographic evaluation of the passage of a bolus from the mouth through the pharynx into the esophagus is based upon identification of specific anatomical landmarks and the integrated motion accomplished by the oral and pharyngeal muscles during swallowing. Twenty-six muscles and 6 cranial nerves must be coordinated to enable the safe performance of the complex physiological task of transporting liquids and firm food from the mouth into the esophagus. The following discussion and illustrations of pharyngeal anatomy and physiology are pertinent to an understanding of normal swallowing function.

Dynamic imaging of the pharynx.

The technique of dynamic imaging of the pharynx and some supplementary maneuvers which can be tailored to the individual patient's needs are discussed in detail. An approach to the analysis of normal and abnormal swallowing studies is presented.