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L Hellman

Publications and source records attributed to L Hellman.

225 records · Page 13Linked to original sources

Analysis of closely related genes by the use of synthetic oligonucleotide probes labeled to a high specific activity.

A method for labeling synthetic oligonucleotide probes to high specific activity is described. The method utilizes two partly complementary oligonucleotides that are labeled by a fill-in reaction using the Klenow fragment of DNA polymerase I and four alpha 32P-nucleoside triphosphates. Such probes can, in combination with Southern blot analysis, be used for routine analysis of individual genes in multigene families.

Amino Acid Sequence↗

Cloning and structural analysis of IgM (mu chain) and the heavy chain V region repertoire in the marsupial Monodelphis domestica.

To address the question of the Ig isotype repertoire of non placental mammals, we have examined the Ig expression in the marsupial Monodelphis domestica (grey short tailed opossum). Screening of an opossum spleen cDNA library has previously led to the isolation of full length clones for opossum IgG (gamma chain), IgE (epsilon chain) and IgA (alpha chain). We now present the isolation of several cDNA clones encoding the entire constant regions of the opossum IgM (mu chain). A comparative analysis of the amino acid sequences for IgM from various animal species showed that opossum IgM, within the various animals studied, is the most divergent member of its Ig class. However, it still conforms to the general structure of IgM in other vertebrates. Four Ig classes have now been identified in opossum and only one isotype is apparently present within each Ig class, IgM, IgG, IgA and IgE. Opossum has previously been shown to have a limited VH region diversity, with only two V gene families. Both of these belong to the group III of mammalian VH sequences. This limitation in variability is to some extent compensated for by a large variation in D, P and N regions, both in size and in sequence. However, evidence for the expression of only two functional J segments has so far been detected, which indicates a rather limited diversity also of the J segments in the opossum.

Amino Acid Sequence↗

LHRH responsiveness in anorexia nervosa: intactness despite prepubertal circadian LH pattern.

Consistent with previous findings, six women with primary anorexia nervosa who underwent 24-hour endocrine studies were all observed to have immature (prepubertal or pubertal) patterns of circadian luteinizing hormone (LH) secretion. This abnormality was present despite negligible weight deficit (but active symptomatology) in three of the women. Regardless of the extent of immaturity of circadian pattern, each woman showed a completely normal release of LH in response to the single intravenous administration of luteinizing hormone releasing hormone (LHRH). These findings provide further evidence for the intactness of pituitary function and for the possibility of a functional hypothalamic disturbance in anorexia nervosa. The discrepant finding in certain other studies of inadequate LH response to LHRH in women with anorexia nervosa is reviewed, and the potential influences of differing variables in these studies and the possibility of a heterogeneous illness are emphasized.

Adolescent↗

Elevated daytime urinary excretion of testosterone glucuronide in men with the type A behavior pattern.

Urinary excretion of testosterone glucuronide was compared in 13 men with typical Type A behavior pattern (as determined by structured interviews) and 10 age-matched men with typical Type B behavior pattern. Twenty-four hour urine collections were divided into three periods: 9AM - 6PM , 6PM to bedtime, and bedtime to 9AM . Type A men showed a significantly higher excretion than Type B men in the daytime ( 9AM - 6PM ); the geometric mean value was 24 micrograms in Type A and 15 micrograms in Type B (P less than 0.05). There were no significant differences between Type A and Type B men for the other two time periods. Indicating an elevated daytime testosterone secretion in Type A men, this finding is consistent with a recent report that exposure to laboratory tests of reaction time causes an increase in plasma testosterone levels in Type A but not Type B men. Since a role for testosterone in the genesis of coronary heart disease (CHD) is suggested by the much higher incidence of CHD in men and the acceleration of murine atherogenesis by testosterone, the findings of this and the previous report may represent a mechanism for the elevated incidence of CHD in Type A men.

Adult↗