17 research outputs found
The Phrenic Component of Acute Schizophrenia – A Name and Its Physiological Reality
Decreased heart rate variability (HRV) was shown for unmedicated patients with schizophrenia and their first-degree relatives, implying genetic associations. This is known to be an important risk factor for increased cardiac mortality in other diseases. The interaction of cardio-respiratory function and respiratory physiology has never been investigated in the disease although it might be closely related to the pattern of autonomic dysfunction. We hypothesized that increased breathing rates and reduced cardio-respiratory coupling in patients with acute schizophrenia would be associated with low vagal function. We assessed variability of breathing rates and depth, HRV and cardio-respiratory coupling in patients, their first-degree relatives and controls at rest. Control subjects were investigated a second time by means of a stress task to identify stress-related changes of cardio-respiratory function. A total of 73 subjects were investigated, consisting of 23 unmedicated patients, 20 healthy, first-degree relatives and 30 control subjects matched for age, gender, smoking and physical fitness. The LifeShirt®, a multi-function ambulatory device, was used for data recording (30 minutes). Patients breathe significantly faster (p<.001) and shallower (p<.001) than controls most pronouncedly during exhalation. Patients' breathing is characterized by a significantly increased amount of middle- (p<.001), high- (p<.001), and very high frequency fluctuations (p<.001). These measures correlated positively with positive symptoms as assessed by the PANSS scale (e.g., middle frequency: r = 521; p<.01). Cardio-respiratory coupling was reduced in patients only, while HRV was decreased in patients and healthy relatives in comparison to controls. Respiratory alterations might reflect arousal in acutely ill patients, which is supported by comparable physiological changes in healthy subjects during stress. Future research needs to further investigate these findings with respect to their physiological consequences for patients. These results are invaluable for researchers studying changes of biological signals prone to the influence of breathing rate and rhythm (e.g., functional imaging)
Namib Desert edaphic bacterial, fungal and archaeal communities assemble through deterministic processes but are influenced by different abiotic parameters
The central Namib Desert is hyperarid, where
limited plant growth ensures that biogeochemical processes
are largely driven by microbial populations. Recent
research has shown that niche partitioning is critically
involved in the assembly of Namib Desert edaphic communities.
However, these studies have mainly focussed on
the Domain Bacteria. Using microbial community fingerprinting,
we compared the assembly of the bacterial, fungal
and archaeal populations of microbial communities across
nine soil niches from four Namib Desert soil habitats (riverbed,
dune, gravel plain and salt pan). Permutational multivariate
analysis of variance indicated that the nine soil
niches presented significantly different physicochemistries
(R
2
= 0.8306, P ≤ 0.0001) and that bacterial, fungal and
archaeal populations were soil niche specific (R
2
≥ 0.64,
P ≤ 0.001). However, the abiotic drivers of community
structure were Domain-specific (P < 0.05), with P, clay and
sand fraction, and NH4
influencing bacterial, fungal and archaeal communities, respectively. Soil physicochemistry
and soil niche explained over 50% of the variation in
community structure, and communities displayed strong
non-random patterns of co-occurrence. Taken together,
these results demonstrate that in central Namib Desert soil
microbial communities, assembly is principally driven by
deterministic processes.The South African National Research Foundation (Grant Number N00113-95565) and the University of Pretoria (UP).http://link.springer.com/journal/7922018-01-31hb2017Genetic