Soybean aeroallergen around the port of New Orleans: A potential cause of asthma

There have been reported epidemics of severe asthma in Barcelona, Spain, linked to a 10 kDa low molecular mass (LMM) allergen from soybean hulls that became airborne during unloading of ships. As a preliminary probe of the potential for dispersion of this allergen in USA cities, four automated air samplers were placed around a grain elevator in New Orleans and operated continuously from May to October 1990. The allergen was extracted from the filters and immunochemically assayed for soybean aeroallergen. On 31 separate days, the airborne allergen concentration in at least one of the samples was over 10000 U/m³ similar to those observed in Barcelona on some epidemic days. Areas North and East of the elevator were most affected. Serologie studies showed that of 50 asthmatics from New Orleans who were participants in an unrelated clinical study 4 or 8% demonstrated elevated titers of IgE antibody to LMM soybean allergen. Only 1 of 475 control sera (half of which were also asthmatic) obtained elsewhere in the US was positive for LMM soybean IgE antibody. Based on the findings in this study, there is a great possibility that on some days there is enough soybean allergen in the air and a sufficient frequency of soybean aeroallergen RAST positive asthmatics in New Orleans to warrant further investigation of the contribution of soybean aeroallergen to asthma around the port of New Orleans.Supported by NIAID # A121255. Mayo Clinic and Foundation and Minnesota Lung Association.     

Estimate of mean tissue O2 consumption at onset of exercise in males

A mathematical model has been developed that permitted the calculation of the flow-weighted mean tissue O2 consumption (VO2T) at the onset of a step increase in work rate. From breath-by-breath measurements of alveolar O2 consumption (VO2A) and cardiac output (Q) by impedance cardiography and assumptions about the site of depletion of O2 stores, the rate of change in O2 stores (VO2s) was determined. The sum of VO2A + VO2s = VO2T. Six very fit males performed six repetitions of each of two step increases in work rate. STlo was a transition from rest to 100-W cycling; SThi was a transition from 100- to 200-W cycling. For each work rate transition, the responses of VO2A and Q were averaged over the six repetitions of each subject and the model was solved to yield VO2T. The responses of VO2A, VO2T, and Q after the increase in work rate were fit with a monoexponential function. This function included a time constant and time delay, the sum of which gave the mean response time (MRT). In the STlo test, the MRT of VO2A (24.9 +/- 1.1 s, mean +/- SE) was longer than that of VO2T (15.3 +/- 1.3 s) and of Q (16.5 +/- 6.5 s) (P less than 0.05). The MRT of VO2T and Q did not differ significantly. Also for SThi, the MRT of VO2A (34.4 +/- 3.3 s) was significantly longer than that of VO2T (30.0 +/- 3.4 s) (P less than 0.05). The MRT of VO2T and Q (30.3 +/- 5.5 s) were not significantly different at this work rate either.(ABSTRACT TRUNCATED AT 250 WORDS)     

The growth response of cells in medium made hyperosmolal with electrolytes or mannitol.

A comparison of the growth rates of established human lymphoid and tumor cell lines was performed in nutrient medium made hyperosmolal with mannitol, NaCl, or mixtures of NaCl and KCl at a constant Na/K ratio. It was found that considerably higher osmolalities were attained with mannitol than electrolytes before a reduction in the growth rate of the culture was observed. This suggests that mannitol and electrolytes affected the growth rate through different mechanisms. Mannitol uptake was studied with two of the cell lines and both cell lines were found to be permeable to mannitol. This eventually would have eliminated the osmolality gradient between the interior of the cell and the medium, and could explain why higher osmolalities were obtained with mannitol before the growth rate was effected. In addition, initial experiments showed that these cell lines may also be able to metabolize mannitol.     

The effect of oral l-carnitine on lipoprotein composition in the Watanabe Heritable Hyperlipidemic Rabbit (Oryctolagus cuniculus)

1. We have recently reported the ability of orally administered l-carnitine to lower plasma triglyceride in the Watanabe Heritable Hyperlipidemic Rabbit (WHHL), an animal model of familial hyperlipoproteinemia. 2. In the present studies we examined the effect of l-carnitine administration upon individual lipoprotein subfractions in this animal model. 3. Carnitine feeding resulted in a reduction in very low density lipoproteins (VLDL) and high density lipoprotein (HDL). 4. Compositional analysis revealed a reduction in core triglyceride content with a concomitant increase in protein and phospholipid in VLDL and low density lipoproteins (LDL). 5. Conversely, electrophoretic mobility and apolipoprotein composition were unchanged with l-carnitine. 6. These results further demonstrate the ability of l-carnitine to modulate lipoprotein lipid composition in this animal model of familial hyperlipoproteinemia.     

Importance of oscillations in alveolar gas concentrations in the analysis of rebreathing data

Cyclic rebreathing of a soluble inert gas can be used to estimate lung tissue volume (Vt) and pulmonary blood flow (Qc). A recently proposed method for analyzing such cyclic data (Respir. Physiol. 48: 255-279, 1982) mathematically assumes that ventilation is a continuous process. However, neglecting the cyclic nature of ventilation may prevent the accurate estimation of Vt and Qc. We evaluated this possibility by simulating the uptake of soluble inert gases during rebreathing using a cyclic model of gas exchange. Under cyclic uptake conditions alveolar gases follow an oscillating time course, because gas concentrations tend to increase during inspiration and to decrease during expiration. We found that neglecting these alveolar gas oscillations leads to the underestimation of soluble gas uptake by blood, particularly during the early rebreathing breaths. When continuous ventilation is assumed Vt and Qc are overestimated unless rapid rebreathing rates, large tidal volumes, and gases of moderately low solubility are used. Under these conditions the amplitude of the cyclic oscillations is minimized, the alveolar time course more closely resembles that expected from continuous ventilation, and the resulting errors are minimized. Alternatively, when the effect of oscillating alveolar gas concentrations on mass transfer are considered, these estimation errors can be eliminated without restricting rebreathing rate or gas solubility. We conclude that failure to consider the effect of cyclic rebreathing on the time course of alveolar gas concentrations may result in significant errors when evaluating rebreathing data for Vt and Qc.