Reproducibility of leukotriene D4 inhalation challenge in asthmatics

We have studied the reproducibility of a bronchial leukotriene (LT) provocation test in asthmatics, and the effect of prior treatment with an oral leukotriene D4/E4 antagonist (SR 2640) on LTD4-induced bronchoconstriction in nine asthmatics in a double-blind placebo-controlled randomized cross-over trial. The reproducibility of the bronchial leukotriene provocation test was high. For a specific patient, the replication variance is 0.2303, and the standard deviation is thus 0.4799, corresponding to 48%, i.e. one halving of the dose or half doubling of the dose. SR 2640 antagonised LTD4 induced bronchoconstriction causing a mean shift of 48% to the right of the dose-response curve as compared with placebo (95% confidence interval being 11-137%). This study demonstrates that bronchial LTD4 provocation test is a safe and reproducible method in asthmatics, and that the method can be used to detect LT-antagonism; furthermore that SR 2640 is a weak LTD4-antagonist in asthmatics.     

Sumatriptan increases the proliferation of peripheral blood mononuclear cells from HIV-infected individuals and healthy blood donors in vitro

HIV infection is characterized by the loss of CD4+ T cells as well as the loss of T-cell function, leading to severe immunodeficiency. The proliferative capacity of T cells measured in vitro as responses to antigens and mitogens is severely reduced during HIV infection. An increased level of the intracellular second messenger adenosine 3',5'-cyclic monophosphate (cAMP) has been shown to cause impaired proliferative capacity of peripheral blood mononuclear cells (PBMC) from HIV-infected individuals in vitro. Sumatriptan, a 5HT1d receptor agonist, inhibits the activity of adenylyl cyclases, the enzymes responsible for regulation of the intracellular levels of cAMP. In a preliminary study sumatriptan increased the proliferative responses of PBMC to a polyclonal activator in vitro in 9 of 10 HIV-seropositive individuals (p=0.007), and in 7 of 9 healthy blood donors (p=0.05). This was probably due to a decrease in the intracellular level of cyclic AMP.     

Isolation of HIV from cultures of purified CD4+ lymphocytes.

Isolation of HIV from cultures of CD4+ lymphocytes purified from peripheral blood by indirect panning was optimized and evaluated. Infectious HIV was isolated by single isolation attempts in 98% of 102 HIV-antibody-positive patients (55 had AIDS or ARC and 47 were clinically healthy). The average culture time required for positive cultures was largely independent of the CD4 count of the patients and 87% of the positive isolation cultures from both groups of patients became positive within 14 days of culture. An evaluation of the possible influence of media additives on propagation of HIV showed that: amphotericin-B had a suppressive effect on HIV replication at concentrations recommended for anti-fungal activity; recombinant and human interleukin-2 were equally suitable for both isolation cultures and for propagation of HIV, and polybrene, at a concentration of 2 micrograms/ml in the culture medium had a beneficial effect.     

Uptake of dehydroascorbic acid and ascorbic acid to isolated nerve terminals and secretory granules from ox neurohypophyses

When uptake of L-[14C]ascorbic acid ([14C]AA) to various organs in guinea-pigs was studied after intracardiac injection, the adenohypophysis, pars intermedia, and the neurohypophysis had an uptake per milligramme protein which was about half of the uptake to the adrenals. Adrenal uptake was 20 +/- 2.8 pmol mg-1 protein microCi-1 injected. The uptake to the different parts of the hypophysis was considerably higher than the uptake to pancreas, liver, kidney, spleen and other organs. When isolated nerve endings (neurosecretosomes) from ox neurohypophyses were incubated with a medium containing labelled dehydroascorbic acid ([14C]DHA), the uptake was much slower than when the medium contained labelled ascorbic acid. The uptake of [14C]DHA showed a linear dependence on concentration, and was not influenced by addition of Mg2+ and ATP. Addition of Mg2+ + ATP, omission of Ca2+ and Mg2+ or exchange of Na+ in the medium with K+ had no effect on the uptake of ascorbic acid. When isolated secretory granules from ox neurohypophyses were incubated with a medium containing [14C]DHA, uptake was considerably faster than the uptake when they were incubated in a medium containing [14C]AA. The uptake of dehydroascorbic acid was linear with the concentration in the medium and was not changed by addition of Mg2+ ATP. Addition of 10 mM NH4Cl or exchange of 120 mM K+ in the incubation medium with Na+ did not change the uptake of dehydroascorbic acid. The contents of copper, zinc, iron and cobalt were determined in isolated nerve endings (A) and membranes (B) as well as in lysate (C) from isolated neurosecretory granules. The results (in nmol mg-1 protein) were for Cu: (A): 0.25 +/- 0.01 (SEM), (B): 0.67 +/- 0.16, (C): 0.22 +/- 0.06; for Zn: (A): 0.53 +/- 0.13, (B): 6.97 +/- 0.75, (C): 1.8 +/- 0.53; and for Fe: (A): 15.6 +/- 1.9, (B): 6.92 +/- 0.32, (C): 3.15 +/- 0.43. In all preparations the cobalt content was below the detection limit (less than 5 pmol mg-1 protein).     

Mechanisms of edema formation in myxedema--increased protein extravasation and relatively slow lymphatic drainage.

We assessed extravascular accumulation of albumin and fluid in primary myxedema by measuring metabolic turnover and transcapillary escape of 131I-labeled human albumin in seven patients. In the hypothyroid state, we found a low plasma volume (P less than 0.05), a reduced rate of albumin synthesis and catabolism (P less than 0.01), an increased transcapillary escape rate of albumin (P less than 0.01), a remarkable increase in the extravascular mass of albumin (1500 micronmol; P less than 0.01) and a longer mean transit time through the extravascular spaces in primary myxedema than in other states of generalized edema (P less than 0.05). All variables returned to normal during l-thyroxine treatment. The extravascular accumulation of albumin, and presumably of all other plasma proteins, is important in the generalized edema typically found in myxedema. Inadequate lymphatic drainage may also explain the formation of exudates in the serous cavities that are well known in myxedema.     

24-h evaporative and sensible heat losses in relation to ambient humidity at 24 degrees C in clothed human subjects

The effect of ambient humidity on the energy expenditure of clothed subjects was investigated. Fifty-six healthy men and women, weighing about 65 kg, spent 24 h in a large human calorimeter at 24 degrees C and performed either of two fixed activity programmes. The ambient humidity varied between experiments from 3 to 11 g m-3. The sensible heat output did not vary significantly with humidity but the evaporative heat loss decreased by about 1.5 W for each g m-3 increase in humidity.     

Mosaicism of the CAG repeat sequence in the Huntington disease gene in a pair of monozygotic twins

We report on a pair of monozygotic twins belonging to a family segregating Huntington disease (HD). In routine DNA analysis of blood cells, they displayed three alleles of the CAG repeat sequence in the HD gene. Two different cell lines, carrying the normal allele together with either an expanded allele with 47 CAGs or an intermediate allele with 37 CAGs, were detected in blood and buccal epithelium from both twins. To our knowledge, this is the first case described of HD gene CAG repeat length mosaicism in blood cells. Haplotype analysis established that the 37 CAG allele most likely arose by contraction of the maternal 47 CAG allele. The contraction must have taken place postzygotically, possibly at a very early stage of development, and probably before separation of the twins. One of the twins has presented symptoms of HD for 4 years; his skin fibroblasts and hair roots carried only the cell line with the 47 CAG repeat allele. The other twin, who is without symptoms at present, displayed mosaicism in skin fibroblasts and hair roots. If the proportion of the two cell lines in the brain of each twin resembles that of their hair roots (another tissue originating from the ectoderm), the mosaicism in the unaffected twin would mean that only a part of his brain cells carried the expanded allele, which could explain why he, in contrast to his brother, has no symptoms at this time.     

Effect of age on behavioral and enzymatic changes during thiamin deficiency

Open field behavior and whole brain enzymatic activities were determined during thiamin deficiency in two strains of young, as well as in aged mice. In young CD-1 mice, thiamin deficiency reduced total distance traveled and vertical movements after 7 days and the decline was more than 50% by day 9. The behavioral deficit was highly correlated to decreases in 2-oxoglutarate dehydrogenase activity (KGDH). The open field behavior of Balb/c mice was about 40% less than in CD-1 mice and responded in a qualitatively different manner to thiamin deficiency. The activity of the Balb/c mice increased and then decreased with thiamin deficiency. The activity of 3 month old mice peaked on day 6 (126% of initial score), whereas 10 and 30 month mice showed a much greater increase (about 175% of initial scores), but on day 7. Although the activity of the thiamin dependent enzyme transketolase (TK) was affected similarly at all ages, the activity of KGDH in the aged brain was more sensitive to thiamin deficiency than in the young; KGDH activity declined 41%, 57% or 74% at 3, 10, or 30 months, respectively. Thus, the current mouse model is an attractive one to study the interaction of thiamin deficiency with aging.