Hyperventilation syndrome: clinical, ventilatory, and personality characteristics as observed in neurological practice.

The symptoms of the hyperventilation syndrome (HVS) are sometimes diffuse, and HVS may resemble other clinical conditions. A diagnosis of HVS was made in 25 patients referred for neurological assessment because of atypical, shortlasting, episodic complaints. The referral diagnoses varied within a wide range. A need for more indepth knowledge about this group of patients thus arose. During a provocation test with forced respiration, all patients reported symptoms similar to those during attacks. Eight patients described numbness or paraesthesias with unilateral predominance. End-tidal pCO2 levels were monitored prior to and during a forced hyperventilation test. Compared with controls, the patients had significantly decreased end-tidal pCO2 even during symptom free periods. After hyperventilation, hypocapnia followed a protracted course in the patient group. Sensory symptoms may be asymmetric and mimic focal cerebral disease. Strained respiration may be denied during spontaneous attacks. Personality characteristics were evaluated with the Minnesota Multiphasic Personality Inventory (MMPI). A mean group profile very similar to profiles reported on "pseudoepileptic" patients was found. The profile indicates a neurotic pattern where patients tend to respond to psychological stress with somatic symptoms

Climate change causing phase transitions of walleye pollock (Theragra chalcogramma) recruitment dynamics

In 1976 the North Pacific climate shifted, resulting in an average increase of the water temperature. In the Gulf of Alaska the climate shift was followed (i.e. early 1980s) by a gradual but dramatic increase in the abundance of groundfish species that typically prey on pre-recruitment stages of walleye pollock. In the present study we used a previously parameterized model to investigate the effect of these climate and biological changes on the recruitment dynamics of walleye pollock in the Gulf of Alaska. Simulations covered the 1970–2000 time frame and emphasized the medium-to-long temporal scale (i.e. about 5–10 years) of environmental variability. Results showed that during periods characterized by high sea surface temperature and high predation on juvenile pollock stages, recruitment variability and magnitude were below average, and recruitment control was delayed to stages older than the 0-group. Opposite dynamics (i.e. high abundance and variability, and early recruitment control) occurred during periods characterized by low temperature and predation. These results are in general agreement with empirical observations, and allowed us to formulate causal explanations for their occurrence. We interpreted the delay of recruitment control and the reduction of variability as an effect of increased constraint on the abundance of post age-0 stages, in turn imposed by high density dependence and predation mortality. On the other hand, low density-dependence and predation favoured post age-0 survival, and allowed for an unconstrained link between larval and recruitment abundance. Our findings demonstrate that the dominant mechanisms of pollock survival change over contrasting climate regimes. Such changes may in turn cause a phase transition of recruitment dynamics with profound implications for the management of the entire stock