Thyroid antibodies as a risk factor for Down syndrome and other trisomies.

To test whether the presence of thyroid antibodies in a parent is a risk factor for meiotic nondisjunction, we measured the levels of thyroid antibodies in serum samples drawn during early pregnancy from 101 gravidas who delivered a child with a trisomy, from 11 gravidas who had had a trisomic child in a previous pregnancy, and from 44 of their husbands. For each case mother, three controls were randomly selected from the same population and matched for age, race, sex of the child, and hospital of birth. Cases and controls came from two longitudinal populations, the Child Health and Development Studies (CHDS) and the national Collaborative Perinatal Project (CPP), together comprising more than 70,000 live births. All cases with both a definite diagnosis of trisomy-Down syndrome (DS) or other-and available serum were included. Overall, there was no association between the presence of thyroid antibodies in a mother and a trisomy in her offspring (odds ratio [OR] = .98, confidence interval [CI] = .54-1.85). The lack of association was seen in all three subgroups (DS only, other trisomies, and DS in a previous pregnancy), in all ethnic groups, and in the age groups of white mothers either less than 30 years of age (OR = .80, CI = .40-1.6) or greater than or equal to 30 years of age (OR = 1.26, CI = .82-1.9). In the CHDS population, case fathers, as compared with control fathers, did not have a higher prevalence of thyroid antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)     

Interaction of chlorinated phenols with thyroxine binding sites of human transthyretin, albumin and thyroid binding globulin

Previous results (Brouwer and van den Berg, Toxicol. Appl. Pharmacol., 85 (1986) 301) indicated preferential binding of a hydroxylated metabolite of tetrachlorobiphenyl to transthyretin (TTR) a carrier of thyroxine (T4). In the present study it was investigated whether the T4 binding site of TTR could be occupied specifically by hydroxylated chlorinated aromatic compounds using chlorinated phenol congeners as model compounds in a competition assay with [125I]T4. Chlorinated aromatics such as 2,3-dichlorobenzene and 3,4,3',4'-tetrachlorobiphenyl, and phenols such as 4-hydroxybiphenyl and phenol were inefficient competitors. All chlorinated phenols tested were competitors for the T4 binding site of TTR. The ranking in competition was pentachlorophenol (PCP) greater than trichlorophenols greater than dichlorophenols greater than monochlorophenols. Structures with chlorine in both ortho positions to the hydroxyl group were more efficient competitors. The relative affinity of binding of pentachlorophenol (PCP) to TTR was about twice that of T4. Scatchard analysis showed that PCP mainly decreased the affinity constant K11 while the binding capacity R1 was not altered, indicating a competitive type of inhibition. PCP was also able to compete with T4 sites on albumin with a relative affinity of 0.25. T4 binding to thyroid binding globulin (TBG) was much less affected by interference of PCP (relative affinity 0.001). The results indicate a specific interaction of chlorophenols with the T4 binding site of TTR.     

Continuous flow microcalorimetric measurement of heat production in white adipose tissue from obese (ob/ob) mice and their lean littermates

Heat production, free fatty acid and glycerol release from white adipose tissue fat pads from obese (ob/ob) mice and their lean littermates are determined. Heat production was significantly lower in obese mice compared to lean mice when expressed on wet weight basis but not when expressed on DNA basis. Noradrenaline significantly increased the heat production in fat pads from both groups of animals. However, the increase in heat production due to noradrenaline addition in fat pads from lean mice was significantly higher than in fat pads from obese mice. The release of free fatty acids and glycerol before incubation with noradrenaline was similar from fat pads from both groups of animals. Addition of noradrenaline to the fat pads increased the release of free fatty acids and glycerol in both groups of animals, but the increase was significantly larger from fat pads from lean mice. In the absence of noradrenaline the free fatty acid/glycerol ratio (mol/mol) in the effluent was 7.9:1 and 4.8:1 for lean mice and obese mice, respectively. In the presence of noradrenaline the ratio decreased to 3:1 for both groups of animals.     

Oxygen uptake of carp,Cyprinus carpio,swimming in normoxic and hypoxic water

Synopsis Oxygen uptake (V_{o 2}) was measured in carp of approximately 40 cm length swimming at controlled variable oxygen tensions (P_{o 2}). At P_{o 2}> 120 mm Hg V_{o 2} increased with an increase in swimming speed from 5.6 to 11.3 cm · sec^–1. Extrapolation of V_{o 2} to zero activity at P_{o 2} = 140 mm Hg revealed a standard O₂ uptake of 36.7 ml O₂ · kg^–1 · h^–1 at 20° C. At the lowest swimming speed (5.6 cm · s^–1) the oxygen uptake increased when the water P_{o 2} was reduced. A near doubling in V_{o 2} was seen at P_{o 2} = 70 mm Hg compared to 140 mm Hg. At higher swimming speeds in hypoxic water V_{o 2} decreased relative to the values at low swimming speeds. As a result the slope of the lines expressing log V_{o 2} as a function of swimming speed decreased from positive to negative values with decreasing P_{o 2} of the water. pH of blood from the caudal vein drawn before and at termination of swimming at P_{o 2} = 70 mm Hg and 100 mm Hg did not show any decrease in relation to rest values at P_{o 2} = 140 mm Hg. Blood lactate concentration did not increase during swimming at these tensions.     

Effect of leupeptin on the intracellular degradation of asialofetuin in isolated rat hepatocytes

The effect of the protease inhibitor leupeptin on the intracellular distribution of [14C]-sucrose-asialofetuin in isolated rat hepatocytes was investigated. Leupeptin had no effect on the uptake but reduced the degradation of asialofetuin. Fractionation of hepatocytes by isopycnic centrifugation in sucrose gradients indicated that prolonged treatment with leupeptin inhibited the uptake of asialofetuin into the lysosomes. Therefore, leupeptin inhibits degradation of asialofetuin both by inhibiting intralysosomal proteolysis and transport of endocytosed asialofetuin to the lysosomes.     

Spring migration of some anadromous freshwater fish species in the northern Bothnian Sea

Quantitative estimations of spring migrating fish have been made in the mouth part of the small coastal river Ängerån which flows into the northern Bothnian Sea (63°35N, 19°50E). In 1981 nearly 3 000 fish were counted ascending to the spawning grounds in the lower reaches of the Ängerån. These species, such as pike, perch, roach and ide, adapted to the oligohaline environment in the Bothnian Sea for most of the year, migrate to spawn in the coastal stream. The reason for these migrations can be interpreted to indicate that the Ängerån offers more favourable water temperature conditions at spawning time compared with the Bothnian Sea, which is ice-covered up to the beginning of May. The most important result of the investigation in the Ängerån is that these fish species, in the same way as the salmonids, return to theirhome-stream every year as adults.Andreasson & Petersson (1982) listed 69 species of fish in the oligohaline Gulf of Bothnia (Table 1) where salinity varies from 2 near the mouth of the River Torneäly to 6 in the vicinity of the Åland Islands (Fig. 1). The fish fauna comprises freshwater and marine species, fish migrating between brackish and freshwater rivers and streams, and recently introduced non-endogenous species.Andreasson & Petersson (1982) designated only five species as anadromous migrators, whereas our studies show that 11 species migrate from the sea to spawn in the Ängerån, a small river discharging into the northern Bothnian Sea (Fig. 2). Earlier reports on these migrations have been given by Berglund (1978) and Johnson (1978, 1982) and for another small stream in the area by Berg (1982).The present paper describes the annual spring migrations of pike, perch, roach and ide between the northern Bothnian Sea and the Ängerån, for the year 1981.