Obesity and weight gain are associated with increased incidence of hyperinsulinemia in non-diabetic men.

We investigated the temporal relationships between obesity, weight change and hyperinsulinemia in a population-based 4-year follow-up study of 695 middle-aged, non-diabetic, and normoinsulinemic men. Thirty-eight men developed hyperinsulinemia during the follow-up (fasting serum insulin > or = 12.0 mU/l). In logistic regression analysis adjusting for other risk factors, men with body mass index of > or = 26.7 kg/m2 (highest third) had a 6.6-fold (p = 0.001) risk of developing hyperinsulinemia, compared with men with body mass index of < 24.4 kg/m2 (lowest third). Correspondingly, men with waist-to-hip ratio of > or = 0.95 (highest third) had a 3.5-fold (p = 0.028) incidence of hyperinsulinemia compared with men with waist-to-hip ratio of < 0.90 (lowest third). Weight gain in middle age and weight gain from the age of 20 years to middle age were also associated with increased risk of hyperinsulinemia. Hyperinsulinemia at baseline was not associated with weight gain during the follow-up. This prospective population-based study emphasizes the importance of avoiding obesity and weight gain during adulthood in preventing hyperinsulinemia.     

Bryophyte vegetation in a wooded meadow: relationships with phanerogam diversity and responses to fertilisation

In the Laelatu wooded meadow in Estonia, famous for its phanerogam diversity, the bryophyte community has been investigated in order to compare its flora and diversity relationships with those of the vascular plant community. Ninety-six bryophyte species were found, 13 of them are hepatics; the majority of the bryophytes are epigeic species common to meadows and forests, including many calciphilous species. Vascular plants and bryophytes display opposite responses to fertilisation. For vascular plants, fertilisation increases the coverage and diminishes the number of species, while for bryophytes it diminishes coverage and increases the number of species. The relationship between the number of species in small plots and the total number of species in the area is similar for vascular plants and bryophytes. No significant changes in the bryophyte community in Laelatu wooded meadow has been detected during the last 30 years.     

Effects of mild physical exercise on serum lipoproteins and metabolites of arachidonic acid: a controlled randomised trial in middle aged men.

To study the effects of physical exercise on biochemical risk factors for ischaemic heart disease 31 healthy middle aged men undertook regular physical exercise for two months and 29 served as controls in a randomised trial. In the men taking regular exercise serum cholesterol concentrations increased 26% more in the high density lipoprotein subfraction two (HDL2) and decreased 31% more in the subfraction three (HDL3) and 9% more in the low density lipoprotein fraction than in the control group. A tendency towards increased plasma 6-keto-prostaglandin F1 alpha concentration and decreased serum thromboxane B2 concentration was found during the period of regular exercise, but prostaglandin E2 concentrations remained unchanged. The increase in plasma 6-keto-prostaglandin F1 alpha concentration was associated with an increase in serum HDL2 cholesterol concentration in the group taking regular exercise. Our data suggest that mild regular physical exercise favourably influences cholesterol distribution in serum lipoproteins in healthy middle aged men and may have beneficial effects on circulating metabolites of arachidonic acid.     

Comparison of gel permeation chromatography, density gradient ultracentrifugation and precipitation methods for quantitation of very-low-, low- and high-density lipoprotein cholesterol

Human VLDL, LDL and HDL (very-low-, low- and high-density lipoproteins) were isolated from plasma by gel permeation chromatography with one pre-ultracentrifugation step. The column effluent was monitored at 280 nm. The cholesterol content of the fractions correlated well with fractions from sequential ultracentrifugation (VLDL, r = 0.839; LDL, r = 0.924; HDL, r = 0.766) or precipitation (LDL, r = 0.975; HDL, r = 0.972) methods. The average triglyceride, phospholipid and protein compositions of the separated lipoprotein fractions were close to those of the ultracentrifugally isolated fractions reported previously. Apolipoproteins A1 and B were determined from fractions to confirm the right distribution between different lipoproteins.     

Infection of human peripheral blood mononuclear cells with a temperature-sensitive mutant of measles virus.

A stable temperature-sensitive mutant of measles virus (MV ts38) was used to study the mechanism of virus-mediated immune suppression of peripheral blood mononuclear cells in vitro. Both unstimulated and phytohemagglutinin-stimulated cultures released infectious virus at 32 degrees C, whereas no virus was released at 37 degrees C, although both viral RNA and viral proteins were synthesized. However, the response of the lymphoid cells to phytohemagglutinin, concanavalin A, and herpes simplex virus antigen was decreased in the presence of MV ts38 at 37 degrees C. The viability of infected cells was not diminished, therefore excluding cell death as a reason for immunosuppression. Interleukin 2 did not play a role in the inhibitory effect of MV ts38. Antibodies to alpha interferon partially reversed the inhibitory effect of the virus infection on lymphocyte mitogenesis, thus implying that alpha interferon plays a role in the immunosuppression. Depletion experiments indicated that adherent cells play a greater role in the measles virus-induced immunosuppression than nonadherent cells. However, monocyte maturation to macrophages had no effect on the degree of immunosuppression.     

Effect of sensory neuropeptides on canine bronchial and pulmonary vessels in vitro

Sensory neuropeptides may be important in the noncholinergic component of parasympathetic vasodilation in the tracheobronchial circulation. We studied the effects of substance P (SP), neurokinin A (NKA), neurokinin B (NKB) and calcitonin gene-related peptide (CGRP) on the isolated canine bronchial artery and used pulmonary artery and vein of similar size for comparison. CGRP (10pM-300nM) was a potent relaxant of the bronchial and pulmonary arteries, and the pulmonary vein with equal potency in all vessels. SP in low concentrations (10pM-100nM) caused vasodilation of the precontracted bronchial artery and in high concentration (10-100 microM) contracted the vessel from resting tone. SP also relaxed the pulmonary artery and vein. NKA and NKB caused relaxation in all three vessels. All of the vascular effects of the sensory neuropeptides were concentration-dependent. The order of potency of the neuropeptides in the bronchial and pulmonary artery was SP greater than NKA greater than CGRP greater than NKB. In the pulmonary vein NKB caused a much larger relaxation than SP and NKA but it was less potent than either NKA or CGRP. Capsaicin (1 microM) caused a large contraction of the bronchial artery, similar in magnitude to the contraction caused by high dose of SP. Neuropeptide Y was also studied and found to cause no consistent constriction of any of the vessels studied. In conclusion, CGRP is a universal dilator of the bronchial and pulmonary blood vessels. SP and NKA exert their main effect on arterial vasomotor tone, whereas NKB is the only tachykinin producing marked dilation of the pulmonary vein.     

Activation of pro-urokinase and plasminogen on human sarcoma cells: a proteolytic system with surface-bound reactants

Human HT-1080 fibrosarcoma cells produce urokinase-type plasminogen activator (u-PA) and type 1 plasminogen activator inhibitor (PAI-1). We found that after incubation of monolayer cultures with purified native human plasminogen in serum-containing medium, bound plasmin activity could be eluted from the cells with tranexamic acid, an analogue of lysine. The bound plasmin was the result of plasminogen activation on the cell surface; plasmin activity was not taken up onto cells after deliberate addition of plasmin to the serum-containing medium. The cell surface plasmin formation was inhibited by an anticatalytic monoclonal antibody to u-PA, indicating that this enzyme was responsible for the activation. Preincubation of the cells with diisopropyl fluorophosphate-inhibited u-PA led to a decrease in surface-bound plasmin, indicating that a large part, if not all, of the cell surface plasminogen activation was catalyzed by surface-bound u-PA. In the absence of plasminogen, most of the cell surface u-PA was present in its single-chain proenzyme form, while addition of plasminogen led to formation of cell-bound two-chain u-PA. The latter reaction was catalyzed by cell-bound plasmin. Cell-bound u-PA was accessible to inhibition by endogenous PAI-1 and by added PAI-2, while the cell-bound plasmin was inaccessible to serum inhibitors, but accessible to added aprotinin and an anticatalytic monoclonal antibody. A model for cell surface plasminogen activation is proposed in which plasminogen binding to cells from serum medium is followed by plasminogen activation by trace amounts of bound active u-PA, to form bound plasmin, which in turn serves to produce more active u-PA from bound pro-u-PA. This exponential process is subject to regulation by endogenous PAI-1 and limited to the pericellular space.     

Productivity of Daphnia longispina in a highly humic boreal lake

The development of the Daphnia longispina (O. F. Müller)population in a highly humic boreal lake was followed throughoutone growing season, and the amount of secondary production wasestimated in relation to primary production and available foodresources. The growth rate method was applied in the secondaryproduction measurements. Daphnia longispina did not appear inthe water column until 16 May, after which the animals werepresent throughout the growing season. The population showedthree density peaks; the first appeared in early June, and thesecond and third in mid-July and at the beginning of September,respectively. Somatic production followed a seasonal pattern,with highest production rates in midsummer. The maximum valueof 127 mg C m^–2day^–1 was recorded at the beginningof July. The total annual net production of D. longispina was7.9 g C m^–2. During most of the growing season, the primaryproductivity in the lake was well below 100 mg C m^–2 day^–1and the total annual productivity of photosynthetic algae was5.0 g C m^–2. We conclude that in this lake the zooplanktonpopulation did not rely on phytoplankton primary productionas a sole carbon source, but that most of the carbon must haveoriginated from bacterial production either directly or througha microbial loop.     

3H]-adenine metabolism and radiation damage during in vitro development of the kidney.

We followed the early post-induction changes in nucleic acid synthesis of the metanephric kidney anlage in vitro. Enhanced incorporation of [3H]-thymidine and [3H]-adenine was detected, but several factors were shown to influence the interpretation of such in vitro experiments. The incorporation is dependent not only on the stage of development of the target organ but also on its transfer to organ culture, as early rudiments require an "adaptive" pre-cultivation to stabilize their metabolism; at more advanced stages growth and DNA synthesis proceed without delay. Another potential artifact is radiation damage which is caused by the incorporated radioisotope and can be detected in prolonged cultures. A [3H]-adenine pulse of more than 1 microCi/ml for 2 hr leads to definite growth retardation, and a 10-microCi/ml pulse causes extensive cell death and atrophy on a 4- to 6-day subculture. The radiation damage is dose-dependent and of variable severity in the different cell lineages within the organ. Since the radioisotope doses were in the range of those commonly used for monitoring cell proliferation and metabolism, we stress the risk of obtaining artifactual results, especially in prolonged cultures after pulse-labeling.     

Planktonic food chains of a highly humic lake

The development and metabolism of epilimnetic plankton from a highly humic lake was followed in late summer, when the predominant zooplankton species, Daphnia longispina, was very abundant (ca. 200 ind. l^?1). The experiment was made in two tanks: one with an unaltered plankton assemblage and one with larger zooplankton removed. The scarce phytoplankton community was also simple, consisting mainly of one Cryptomonas and two Mallomonas species. The abundance and species composition of smaller plankton was heavily influenced by grazing of Daphnia. In particular, the biomass, of heterotrophic flagellates increased after the removal of Daphnia. The biomass and production of bacterioplankton were not affected, and remained several times higher than that of phytoplankton. Bacterial production and grazing on bacteria were balanced, and when Daphnia was removed its grazing activity was compensated by flagellates. The removal of Daphnia did not affect the respiration or community net production of plankton. Among organisms smaller than zooplankton, bacteria seemed to be responsible for most of the respiration. The community net production was consistently negative even at the water surface, indicating an allochthonous carbon source. The results suggest that phytoplankton primary production was insufficient for the secondary production in the epilimnetic water of the study lake. The food requirements of bacteria and zooplankton, as well as of flagellates, each exceeded that supplied by phytoplankton primary production. The simple food chains in this experiment made it possible to reveal the functioning of the community so completely that dissolved organic matter is certainly comparable to or exceeds the importance of phytoplankton primary production as an energy and carbon source for food webs in this humic lake.