Reciprocity Versus Rhythmicity in Spontaneous Alternations of Nasal Airflow

Active anterior rhinomanometry was used to observe nasal airflow in five men and four women (ages 18–30). Measurements were obtained for each nasal passage every 5 min throughout an uninterrupted 8-hr session. Facial skin temperature from the left and right side of the face was recorded simultaneously from thermocouples. Observations were made during the months of May and June; subjects were allowed to maintain their routine diurnally active schedules prior to observation. Airflow in the two passages showed a significant negative correlation (i.e. Was reciprocal) in 44% of subjects (N= 9). Autocorrelation and spectral analysis of the airflow data found evidence of periodicity in 39% of individual nostrils and 56% of subjects. Mean estimated period was 4.5 ± 1.0 hr (range 3.5–6.0 hr). Only 22% of subjects showed statistical evidence of periodicity in both nostrils (i.e. a “nasal cycle”). Left- and right-side facial skin temperatures changed in parallel rather than reciprocally, but showed evidence of periodicity in 50% of hemifacial time series (56% of subjects), with an estimated period of 3.8 ± 1.0 hr (range 2.3–5.0).     

Unique organization of the frontonasal ectodermal zone in birds and mammals

The faces of birds and mammals exhibit remarkable morphologic diversity, but how variation arises is not well-understood. We have previously demonstrated that a region of facial ectoderm, which we named the frontonasal ectodermal zone (FEZ), regulates proximo-distal extension and dorso-ventral polarity of the upper jaw in birds. In this work, we examined the equivalent ectoderm in murine embryos and determined that the FEZ is conserved in mice. However, our results revealed that fundamental differences in the organization and constituents of the FEZ in mice and chicks may underlie the distinct growth characteristics that distinguish mammalian and avian embryos during the earliest stages of development. Finally, current models suggest that neural crest cells regulate size and shape of the upper jaw, and that signaling by Bone morphogenetic proteins (Bmps) within avian neural crest helps direct this process. Here we show that Bmp expression patterns in neural crest cells are regulated in part by signals from the FEZ. The results of our work reconcile how a conserved signaling center that patterns growth of developing face may generate morphologic diversity among different animals. Subtle changes in the organization of gene expression patterns in the FEZ could underlie morphologic variation observed among and within species, and at extremes, variation could produce disease phenotypes.     

Distribution of trace elements within bones in nasal cavity and labyrinth in humans

Measurements of trace element concentrations within bones in nasal cavity and labyrinth have shown large variations, both with a single bone and between different bones of a same individual. Factors that influence trace element levels include: metabolic activity, environmental effects, sex, and age. Detection of characteristic X-rays has been shown to be a convenient method for the measurement of concentration profiles, micropixe for micrometer variations, and X-ray centration profiles, micropixe for micrometer variations, and X-ray fluorescence for millimeter variations.     

Adherence ofMycobacterium leprae to the nasal mucosa is influenced by surface integrity and viability

The intranasal route is one of the main routes of Mycobacterium leprae infection and there is paucity of information regarding the mode of spread of the pattern. The adherence of M.leprae to the nasal mucosa, its trapping within the sinuses of the head, and its fate after entry into the host was studied using mouse model. A comparison of the adherence profile of M. leprae and Mycobacterium tuberculosis showed that while larger numbers of M. tuberculosis were demonstrated within lungs, greater numbers of M.leprae were present within the sinuses of the head. Adherence of M.leprae to the nasal mucosa was dependent on surface integrity since opsonization and heat killing resulted in decreased numbers of M.leprae in the nasal sinuses and a greater amount entering the lungs. The adherence appeared to the independent of the viability of the bacilli, as similar numbers of formalin-fixed, rifampicin-treated and viable M.leprae entered the lungs in the initial stages. However the numbers of rifampicin-treated M. leprae in the nasal sinuses were 12-fold lower than the numbers of viable M.leprae. These results indicated that both viability and surface integrity were important in the entry of M.leprae and it’s consequent dissemination.     

Spontaneous and induced blocking and unblocking of phloem transport

Abstract Steady-state labelling with ¹¹CO₂ was used to observe the blocking of phloem transport, induced by chilling short regions of stems or petioles of velvetleaf (Abutilon theophrasti Medic.) or cotton (Gossipium hirsutum L.). The abruptness of these blockages was evidenced by sharp decreases in ¹¹C activity below, and increases above a 2 to 3 cm region cooled from 28°C to 18 or 13°C for periods as short as 2 min. Abrupt unblocking of transport in velvetleaf occurred a few minutes after rewarming, as evidenced by a sharp rise and and overshoot in ¹¹C activity. Recovery of transport in cotton was more prolonged and was marked by occasional spontaneous blocking and unblocking of transport at various points along the petiole or stem, not necessarily in the cooled region. Similar spontaneous events were often observed in undisturbed cotton plants, but only rarely in velvetleaf.     

Field determination of denitrification in water-logged forest soils

Abstract Denitrification rates were measured as N₂O production in two water-logged forest soils at monthly intervals. The effect of acetylene inhibition and the addition of nitrate, glucose, acetate and celloboise in field incubations was examined.
N₂O release from the two soils was very low, 26 mg N₂m⁻²y⁻¹ in ash and 178 mg N₂ in alder. In acetylene inhibited incubations N₂O production was higher, 296 and 486 mg N₂m⁻² y⁻¹ in ash and alder respectively. After addition of nitrate and C-sources to a 10 mM concentration, denitrification rates increased to 5–15 times higher values.
The denitrification rates below 4°C were low and most N₂O was produced in late spring and summer.
The highest rate of denitrification during a 50 h incubation experiment occurred between 3 and 23 h.