Enzyme studies on Epstein-Barr virus-transformed lymphoid cell lines from Wolman's disease. Lipases, cholesterol esterase and 4-methylumbelliferyl acyl ester hydrolases

(1) In lymphoid cell lines established by Epstein-Barr virus transformation of B-lymphocytes from normal subjects there exist two lipases hydrolysing triolein (the first one with acid optimum pH and the other one with alkaline optimum pH) and one cholesterol esterase (with acidic optimum pH). The acid triolein lipase (optimum pH 3.75-4.0) and the acid cholesterol esterase are activated by taurocholate (optimal concentration between 1 and 2.5 g/l) whereas alkaline triolein-lipase is inhibited by crude taurocholate. (2) Acid lipase deficiency is demonstrated in lymphoid cell lines from a Wolman's patient, using natural substrates, triolein and cholesteryl oleate (residual activity 5 and 8%, respectively). Thus, this similar deficiency demonstrates that, in lymphoid cell lines, triolein and cholesteryl esters are hydrolysed (under the conditions used here) by a single enzyme, i.e., lysosomal acid lipase muted in Wolman's disease. (3) pH profiles of synthetic substrate hydrolysis show marked differences between methylumbelliferyl oleate and methylumbelliferyl palmitate, and are greatly dependent on the assay conditions used. In the presence of optimal concentrations of taurocholate (1-2.5 g/l), nonspecific carboxylesterases are inhibited and acid lipase is activated: in this case, methylumbelliferyl oleate can be used to demonstrate the acid lipase deficiency in Wolman's lines (15-20% of residual activity). Methylumbelliferyl palmitate hydrolysis is less dependent on assay conditions and thus can be more accurately used for the diagnosis of Wolman's disease, with lower residual activity (10-15%) than using methylumbelliferyl oleate. Thus, Epstein-Barr virus-transformed lymphoid cell lines represent an accurate model system in culture for experimental studies of Wolman's disease.     

The polymerization of actin: II. how nonfilamentous actin becomes nonrandomly distributed in sperm: evidence for the association of this actin with membranes

At an early stage in spermiogenesis the acrosomal vacuole and other organelles including ribosomes are located at the basal end of the cell. From here actin must be transported to its future location at the anterior end of the cell. At no stage, in the accumulation of actin in the periacrosomal region is the actin sequested in a membrane-bounded compartment such as a vacuole or vesicle. Since filaments are not present in the periacrsomoal region during the accumulation of the actin even though the fixation of these cells is sufficiently good to distinguish actin filaments in thin section, the actin must accumulate in the nonfilamentous state.     

Body temperatures during rest and exercise in residents and sojourners in hot climate

Rectal (T_re), mean skin temperature ( _sk) and sweating rate ( ) were measured in 4 residents of temperate climate under acute moderate heat exposure (designated EE in such an experimental situation), after 3 weeks in India (designated as EI) and in 8 Indian residents (designated as II) both at rest and during submaximal exercises at 2 different intensities. At rest, T_re is higher in EI (37.6°C) than in EE (36.8°C, P<0.01) and reaches 37.8°C in II. At the end of exercise, the increment in T_re seems to depend on work load only and to be independent of thermal environment; S follows a similar pattern in the 3 groups of subjects: _sk is altered neither by exercise nor acclimatization. Under chronic heat exposure compared to acute conditions: (1) identical is achieved with higher T_re and similar _sk so that the linear relationships vs T_re is shifted to the right. (2) the T_re — _sk difference is greater at rest and during exercise: hence, skin blood flow, calculated from heat balance equation diminishes. In hot climate, a rise in T_re seems to be an adaptive response which allows the body to reduce skin blood flow.     

Interactive effects of dietary (n-3) polyunsaturated fatty acids and chronic ethanol intoxication on synaptic membrane lipid composition and fluidity in rats.

The influence of dietary polyunsaturated fatty acids on fatty acid composition, cholesterol and phospholipid content as well as 'fluidity' (assessed by fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) probes) of brain synaptic plasma membranes (SPM) and their interactions with chronic ethanol effects were studied in rats fed for two generations with diets either devoid of (n-3) fatty acids (sunflower oil diet), rich in alpha-linolenic acid (soya oil diet) or in long chain (n-3) fatty acids (sunflower + cod liver oil diet). Results were compared with rats fed standard lab chow. Sunflower oil led to an increase in the (n-6)/(n-3) ratio in the membranes with an increase of the 'fluidity' at membrane apolar level; sunflower + cod liver oil decreased the (n-6)/(n-3) ratio without affecting membrane 'fluidity' while no difference was seen between the SPM of rats fed soya oil and standard diet. After 3 weeks alcohol intoxication in rat fed the standard diet: oleic alpha-linoleic acids and cholesterol levels were increased, arachidonic acid and the double bond index/saturated fatty acids were decreased and there was a decrease of 'fluidity' in the lipid core of the SPM. Soya oil almost totally abolished these usually observed changes in the SPM fatty acids composition but increased oleic acid and cholesterol without any change in fluidity. Sunflower oil led to the same general alterations of fatty acid as seen with standard diet but to a greater extent, with decrease of the 'fluidity" at the apolar level and in the region probed by TMA-DPH. When sunflower oil was supplemented with cod liver oil, oleic and alpha-linoleic acids were increased while the 'fluidity' of the apolar core of SPM was decreased. So, the small changes in fatty acid pattern seem able to modulate neural properties i.e. the responses to a neurotoxic like ethanol. A structurally specific role of PUFA is demonstrated by the pernicious effects of the alpha-linolenic acid deficient diet which are not totally prevented by the supply of long chain (n-3) PUFA.     

Consecutive and Simultaneous Competition ELISA of Monoclonal Antibodies: Characterization of Epitope Relationships or Immunoglobulin Idiotypes

Three populations of Arabidopsis thaliana (L.) Heynh. were inoculated with three isolates of Plasmodiophora brassicae Woron. Inoculation of young Arabidopsis plants caused clubbing of roots and, in the late flowering population CrGC 9–4, infection of shoots. In this population, the number of inoculated plants reaching the flowering stage was reduced, and the majority of plants died prematurely. Symptoms of shoot infections were compressed rosettes with thickened and stunted leaves containing resting spores of P. brassicae. The results showed clearly that A. thaliana is susceptible to P. brassicae.     

Changes in the blood flow of the primary carotid and its branches during modifications of the O2 and CO2 composition of alveolar gas]

We measured common carotid blood flow using a range gated Doppler velocimeter, and internal and external blood velocities using a continuous Doppler in 20 lowlanders at sea level, under normal barometric pressure, in 10 subjects in an altitude chamber under a barometric pressure of 462 Torr (61.6 KPa) and then in 5 of them over a 3-weeks period at 3850 m of elevation (475 Torr = 63.3 KPa). The same measurements were also performed in 20 permanent residents at 3850 m. Common carotid blood flow was 15% higher in all subjects exposed to high altitude, due to a lowering in downstream resistances since systemic blood pressure did not change at high altitude. The increase in common carotid blood flow was the result of an immediate increase in internal carotid blood velocities observed in the altitude chamber as well as after the arrival at high altitude, but a few days later those velocities in the internal carotid artery declined to values similar to those observed at sea level. In the same time velocities in external carotid artery rose at high altitude, remained steadily elevated and the result is a permanent increase in common carotid blood flow at altitude. In all subjects we performed the same measurements, during an acute inhalation of gas mixtures to try to quantify the mechanisms controlling the changes in common carotid blood flow while changing gas inhalation. In the limits of the variations in PO2 (60 to 400 Torr) and in PCO2 (30 to 50 Torr) the stimulation by CO2 is twice more efficient than the O2 stimulation on vasomotion.