Effect of temperature on the ethylene-synthesizing systems in apple, tomato and Penicillium digitatum

Arrhenius plots of ethylene-synthesizing systems of apple andtomato showed discontinuities while the plot for Penicilliumdigitatum was linear. Triton X-100 markedly lowered the activationenergies of the apple and tomato systems without altering thatof the fungal system. The data presented suggest that the lipidmicro-environment of the ethylene-synthesizing enzyme systemsin higher plants and P. digitatum are different, and that cellmembrane-cell wall complex may be the site of ethylene-synthesizingenzymic systems in higher plants. ¹ On leave from the M. S. University of Baroda, India. ² On leave from the Agricultural Research Organization, TheVolcani Center, Israel. (Received February 7, 1977; )     

Effects of chest wall vibration on breathlessness during hypercapnic ventilatory response

Vibratory stimulation applied to the chest wallduring inspiration reduces the intensity of breathlessness, whereas thesame stimulation during expiration has no effect or may increasebreathlessness. The purpose of the present study was to determinewhether vibration reduced the intensity of breathlessness duringprogressive hypercapnia with and without the addition of an externalresistive load. A second objective was to see whether the mouthocclusion pressure at 0.2 s(P_0.2) was reduced by thevibratory stimulation. Hypercapnic ventilatory response was conductedin 10 healthy male volunteers with simultaneous measurement of visualanalog scale, P_0.2, and minuteventilation. Hypercapnic ventilatory response was performed andrandomly combined with or without vibratory stimulation (100 Hz) aswell as with or without inspiratory load. With inspiratory load,in-phase vibration did not cause any significant changes in the slopesof P_0.2 and minute ventilation toCO₂, whereas the slope of visualanalog scale to CO₂ significantlydecreased from 0.47 ± 0.15 to 0.34 ± 0.11 (SE) cm/Torr(P < 0.05). We conclude thatin-phase vibration could decrease the slope of breathlessness elicitedby inspiratory load combined with hypercapnia without changing motoroutput.

     

On the reconceptualization of Alzheimer’s disease

In the hope of future treatments to prevent or slow down the disease, there is a strong movement towards an ever‐earlier detection of Alzheimer’s disease (AD). In conjunction with scientific developments, this has prompted a reconceptualization of AD, as a slowly progressive pathological process with a long asymptomatic phase. New concepts such as ‘preclinical’ and ‘prodromal’ AD have been introduced, raising a number of conceptual and ethical questions. We evaluate whether these new concepts are theoretically defensible, in light of theories of health and disease, and whether they should be understood as disease or as an at‐risk state. We introduce a pragmatic view on disease concepts and argue that an evaluation of the reconceptualization of AD should also take its aims and effects into account, and assess their ethical acceptability. The reconceptualization of AD is useful to coordinate research into preventive strategies, and may potentially benefit future patients. However, in the short term, early detection and labelling of ‘preclinical AD’ can potentially harm people. Since there is no treatment available and the predictive value is unclear, it may only create a group of ‘patients‐in‐waiting’ who may suffer from anxiety, uncertainty and stigmatization, but will never actually develop dementia. We conclude that only if the promise of preventive medication materializes, will the reconceptualization of AD turn out unequivocally to be for the better. Otherwise, the reconceptualization may do more harm than good.     

Regulation of ethylene production by phosphate in Penicillium digitatum

Inorganic phosphate regulated ethylene production in shake culturesof Penicillium digitatum. Decreasing the phosphate level ofthe medium from 100 to 0.01 mM markedly increased, about 100-fold,the rate of ethylene production, in 96 hr, which was confinedentirely to the fungal mycelium. Exogenous addition of between0.01 to 100 mM phosphate, to high ethylene producing, low-phosphatecultures strongly inhibited their ethylene production and increasedthe ATP content of the mycelium. Phosphate also inhibited ethyleneproduction in apple slices. Addition of calcium ions to theincubation medium stimulated the production of ethylene in appleslices, subhook epicotyl segments of pea and shake culturesof P. digitatum. We suggest that this stimulatory effect wascaused by the reduction of inhibitory levels of phosphate, whichcomplexed with calcium. Thus, phosphate in conjunction withcalcium may play an important role in regulating ethylene productionnot only in P. digitatum but also in higher plants. ¹ On leave from the Agricultural Research Organization, TheVolcani Center, Israel. ² On leave from the M.S. University of Baroda, India. (Received September 7, 1977; )     

Treatment of osteoporosis with a modified zeolite shows beneficial effects in an osteoporotic rat model and a human clinical trial

The severity of osteoporosis in humans manifests in its high incidence and by its complications that diminish quality of life. A societal consequence of osteoporosis is the substantial burden that it inflicts upon patients and their families. Several bone-modifying drugs have been prescribed to patients with osteoporosis. However, evidence for their anti-fracture efficacy remains inconclusive. To the contrary, long-term use of anti-osteoporotic drugs such as bisphosphonates and Denosumab, an RANKL inhibitor, have resulted in adverse events. We now present an alternative and adjuvant approach for treatment of osteoporosis. The data derive from in vivo studies in an ovariectomized rat model and from a randomized double blind, placebo-controlled human clinical study. Both studies involved treatment with Panaceo Micro Activation (PMA)-zeolite-clinoptilolite, a defined cation exchange clinoptilolite, which clearly improved all bone histomorphometric parameters examined from ovariectomized animals, indicative for increased bone formation. Moreover, intervention with PMA-zeolite-clinoptilolite for one year proved safe in humans. Furthermore, patients treated with PMA-zeolite-clinoptilolite showed an increase in bone mineral density, an elevated level of markers indicative of bone formation, a significant reduction in pain, and significantly improved quality of life compared with patients in the control (placebo) group. These encouraging positive effects of PMA-zeolite-clinoptilolite on bone integrity and on osteoporosis warrant further evaluation of treatment with PMA-zeolite-clinoptilolite as a new alternative adjuvant therapy for osteoporosis.