"Normal-pressure" hydrocephalus. Relationship of clinical and radiographic findings to improvement following shunt surgery

Analysis of 25 patients who fulfilled clinical and radiographic criteria for the diagnosis of "normal pressure" hydrocephalus (NPH) demonstrated (1) a significant relationship between presence of motor signs with good outcome and absence of motor signs with poor outcome following ventricular shunting, (2) symptoms and signs of parkinsonism in 40% of patients in whom the diagnosis of NPH was made, and (3) no reliable relationship between radiographic measurements or cisternogram appearance and outcome following shunting. The clinical picture is the most important factor in selection of NPH patients for surgery.

Mechanisms of bronchial hyperreactivity in normal subjects after upper respiratory tract infection

Inhalation of histamine diphosphate aerosol (1.6 per cent, 10 breaths) produced a 218 +/- 54.6 per cent (mean +/- SE) increase in airway resistance in 16 normal subjects with colds compared with a 30.5 +/- 5.5 per cent increase in 11 healthy control subjects (P less than 0.01). There was no significant difference in mean baseline airway resistance between the two groups. Inhalation of saline produced no significant change in airway resistance in either group. Isoproterenol hydrochloride (0.5 per cent, 1 breath) or atropine sulfate aerosol (0.2 per cent, 20 breaths) each reversed and prevented the increase in airway resistance by histamine, indicating that the bronchoconstriction was caused by smooth muscle contraction and that post-ganglionic, cholinergic pathways were involved in the mechanism. In 6 subjects with colds, citric acid aerosol (10 per cent, 5 breaths) caused bronchoconstriction that lasted up to 30 sec after inhalation, a significantly greater effect than that observed in control subjects or in the same subjects after recovery (P less than 0.05). Prior inhalation of atropine aerosol (0.2 per cent, 20 breaths) prevented the bronchoconstriction after citric acid aerosol in all 6 subjects. The threshold concentration of citric acid that produced cough in 7 subjects with colds was significantly lower than that in control subjects or in the 7 subjects after recovery (P less than 0.05), suggesting that the exaggerated cholinergic response was due to a decreased threshold for stimulation of the rapidly adapting sensory receptors in the airways. We have provided evidence that respiratory viral infections that produce airway epithelial damage temporarily cause these subjects to develop more bronchoconstriction after inhaling smaller doses of histamine than do healthy subjects. The fact that atropine prevents this response and that the threshold to cough is temporarily decreased is compatible with our hypothesis that airway epithelial damage by infection exposes and, thus, "sensitizes" the rapidly adapting airway receptors to inhaled irritants, causing increased bronchoconstriction via a vagal reflex. Damage to the airway epithelium may occur as a result of mechanical factors, inhaled chemicals, and pollutants, such as ozone, infections, or perhaps as a result of the action of materials released endogenously (e.g., from mast cells, white blood cells, or platelets). "Sensitization" of rapidly adapting sensory receptors in the airways may be an important factor in asthma and in other diseases of airways.

Toxoplasma gondii: parasitology and transmission

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Reflex apnea, bradycardia, and hypotension produced by serotonin and phenyldiguanide acting on the nodose ganglia of the cat

Five to 20 µg of phenyldiguanide or serotonin (5-HT) injected into the common carotid arteries of cats (anesthetized with chloralose and urethan) elicited an immediate apnea, usually accompanied by bradycardia and hypotension. The response persisted after ligation of the external carotid and lingual arteries. Since the internal carotid is occluded in the cat, the receptors must be in the distribution of the occipital or ascending pharyngeal arteries. Denervation of the carotid sinus and carotid body, removal of the superior cervical ganglion, section of the vagosympathetic trunk below the nodose ganglion, and extracranial section of cranial nerves IX, XI, and XII did not diminish the response. Section or procaine block of the extracranial supranodose vagus or removal of the nodose ganglion usually abolished the apnea and bradycardia; hypotension still occurred in many cats. Examination of the nodose ganglion by fluorescence microscopy revealed nests of intensely fluorescent cells similar to type 1 carotid body cells. Although previous investigators have reported that veratrnm alkaloids or acetylstrophanthidin causes vomiting or bradycardia by an action on the nodose ganglion, this is the first demonstration that a naturally occurring substance (5-HT) stimulates receptors in the nodose ganglion, causing reflex apnea and hypotension in addition to bradycardia.

Toxoplasmosis: Epidemiology and Medical Importance

Developmental stages of T. gondii are described. The recent studies on fecal transmission of T. gondii are reviewed with the suggestion explored that T. gondii is a coccidian parasite which produces an intestinal cyst previously named Isopora bigemina, the intestinal reproductive stages of which are specific for the felines. Human illness associated with this parasite is reviewed and its importance described.

Stimulation of the carotid chemoreceptors of the dog by dopamine

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Factors affecting distribution of iodide in brain and cerebrospinal fluid

The effects of acetazolamide, sodium perchlorate, ouabain, and of iodide loading on the processes controlling I131 and inulin-C14 distribution in the brain and CSF were studied in nephrectomized rats. It was observed that the first three drugs increased the concentration of both iodide and inulin in the brain and CSF after intracisternal administration of the tracers. It was concluded that acetazolamide reduced the rate of formation and flow of CSF, that perchlorate primarily decreased active iodide transport, and that ouabain slightly reduced CSF formation and flow. Iodide loading increased the CSF/plasma iodide ratio, expressed as percent (CSF iodide space), from 1.97 to 42.17, and the comparable values for brain were 2.02 and 11.76, respectively. The results suggest that the primary factors in the control of iodide distribution in the CNS are the following: 1) an active iodide transport system between CSF and blood, 2) limited permeability to iodide of the structures between blood and CSF and between blood and brain, and 3) relatively free diffusion of iodide between brain and CSF.