Argenine decarboxylase from Escherichia coli. I. Purification and specificity for substrates and coenzyme.
Explore the source record for details and available documents.
Arginine↗
Biomedical subjects
S L Blethen
Publications and source records attributed to S L Blethen.
Characteristics of arthropod arginine kinases.
Explore the source record for details and available documents.
Amino Acids↗
Purification of arginine kinase from lobster and a study of some factors affecting its reactivation.
Explore the source record for details and available documents.
Adenine Nucleotides↗
Possible abnormalities of steroid secretion in children with Smith-Lemli-Opitz syndrome and their parents.
In early infancy, two unrelated children with Smith-Lemli-Opitz syndrome were found to have elevated levels of androgen sulfates. When the steroid conjugates in the serum of normal infants were hydrolyzed and chromatographed on Sephadex LH-20, 4 androgen containing peaks (I, II, III, IV) were found. In the serum from these two infants with Smith-Lemli-Opitz syndrome, Peaks I and III were increased, but Peaks II and IV were absent. The parents of the two children, and of three additional unrelated children with Smith-Lemli-Opitz syndrome, had exaggerated 17-hydroxyprogesterone responses to an intravenous bolus of ACTH. These findings suggest that a defect in steroid metabolism may be linked to the Smith-Lemli-Opitz syndrome.
17-alpha-Hydroxyprogesterone↗
Sex hormone-binding globulin and thyroxine-binding globulin levels in premature thelarche.
Premature thelarche is defined as the isolated development of breast tissue in girls less than 8 years of age. Although breast development is an estrogen-dependent process, these girls do not have elevated serum estrogen levels, and the hormonal basis for their condition is unclear. We studied the levels of two estrogen-dependent transport proteins, sex hormone-binding globulin (SHBG) and thyroxine-binding globulin (TBG), in order to determine if there was evidence for a more subtle estrogen effect in girls with premature thelarche. SHBG levels in girls with premature thelarche were not significantly different from those of prepubertal girls of the same ages and were significantly lower than those in girls undergoing pubertal development at the appropriate age (P less than 0.05) and in normal women (P less than 0.001). There was no statistically significant difference in TBG levels between the girls with premature thelarche and prepubertal controls. There was also no significant difference in TBG levels between prepubertal girls and girls in early puberty. In contrast, women had TBG levels that were significantly lower than those in all girls studied. We conclude that the estrogen exposure (whether endogenous or exogenous) of girls with premature thelarche is less than that of girls in early true puberty and similar to that of other prepubertal girls. Further, changes in serum TBG are not as sensitive an indicator of estrogen effect as is breast development or changes in SHBG. This study also suggests that large amounts of exogenous estrogens are not an element in the development of premature thelarche.
Adolescent↗
The relationship between biochemical adrenarche and decreasing alpha-2-macroglobulin levels in children.
Alpha-2-macroglobulin (alpha 2-MG) is one of the major serum protease inhibitors in adults and appears to be even more important in children. Previous studies have suggested that alpha 2-MG levels are dependent upon age and sex. In order to evaluate the influence of biochemical adrenarche on alpha 2-MG, we compared alpha 2-MG concentrations in normal children and children with premature adrenarche (PA) with levels of dehydroepiandrosterone sulfate (D-S), the marker for biochemical adrenarche. We found that alpha 2-MG was inversely correlated with age and with log10 [D-S] in the normal children. In the children with PA, the alpha 2-MG levels were significantly lower than predicted based on age alone and were similar to the predicted values based on log10 [D-S] levels. We suggest that adrenarche is the process that causes the age-related changes in alpha 2-MG.
Aging↗
Thyroid function in children with perinatally acquired antibodies to human immunodeficiency virus.
We measured T4, T3, TSH, and TBG in 53 children (both asymptomatic and symptomatic) with human immunodeficiency virus (HIV) antibodies, and 17 controls. Although most had normal T3 and T4 levels, two children with acquired immuno-deficiency syndrome (AIDS), who were very ill when studied, had low T3 values. TBG and TSH levels were higher in children with AIDS than in other HIV-infected children or controls (P < 0.005). Increased TSH levels were found in 5 children with AIDS who were recovering from severe illnesses. TSH levels returned to normal without treatment. In summary: 1) the pattern of thyroid abnormalities in children with AIDS was different from that seen in healthy controls, critically ill children, other HIV-infected children, and HIV-infected adults; 2) if an increased TSH is found, measurement should be repeated before instituting thyroxine therapy; 3) an increased TBG is not seen in HIV-infected children until clinically evident AIDS is present.
Acquired Immunodeficiency Syndrome↗
Growth hormone treatment in growth retarded children with end stage renal failure: effect on free/dissociable IGF-I levels.
Growth retardation in children with endstage renal disease (ESRD) is associated with normal to slightly low concentrations of insulin-like growth factor (IGF)-I and increased concentrations of IGF-binding proteins (IGFBPs) in serum. Consequently, IGF-I bioactivity is reduced in serum from uremic patients presumably due to a decrease in the concentration of free IGF-I. Improvement of linear growth with growth hormone (GH) treatment of uremic children is thought to be due to increased IGF-I/IGFBP ratio, thus resulting in increased free IGF-I levels during treatment. The purpose of the present study was to determine whether free/dissociable IGF-I levels are in fact low in uremic children and whether increased growth velocity during GH treatment is associated with an increase in the free IGF-I concentration. Serum total and free/dissociable IGF-I concentrations were measured in 5 children with ESRD before and during treatment with GH, and in control children matched for age, pubertal status, and body mass index. Height velocity increased from 3.7 +/- 1.0 cm/yr to 6.5 +/- 1.2 cm/yr with an increment in height SDS at the end of the first year of GH treatment. Free/dissociable IGF-I concentrations tended to be lower in uremic children compared to control children (3.0 +/- 0.3 vs 7.3 +/- 2.1 micrograms/l, respectively). During GH treatment, free/dissociable IGF-I levels increased significantly to 8.5 +/- 1.0 micrograms/l at 3 months and 6.9 +/- 1.4 micrograms/l at 6-24 months, p < 0.05 compared to pretreatment. Total IGF-I levels were 243 +/- 18 micrograms/l in children with ESRD before treatment and these values also increased during GH treatment (740 +/- 114 micrograms/l at 3 months and 442 +/- 44 micrograms/l at 6-24 months, p < 0.05, compared to pretreatment). Total IGF-I concentration in the control group was 439 +/- 114 micrograms/l. These results support the hypothesis that growth retardation in children with chronic renal failure is associated with a reduction in the concentration of free, biologically available IGF-I, and that increased growth velocity during GH treatment of these children is associated with restoration of free IGF-I concentrations.
Body Height↗
Growth hormone isoforms in a girl with gigantism.
Several previous investigations have suggested that there may be different growth hormone isoforms in patients with acromegaly. We used three different site-specific monoclonal antibodies (MAbs) to investigate growth hormone (GH) isoforms in serum from an 8 year-old girl with a GH and prolactin secreting adenoma. The pattern of GH-immunoreactivity was dependent on the circumstances of collection. Serum obtained after oral glucose had very little cross reactivity with MAb 352 although concentrations of up to 15 micrograms/l were found with two other MAbs, 033 and 665. MAb 352 does not recognize the 20,000 dalton isoform of GH (20K) while both MAb 033 and 665 do. The same pattern of GH immunoreactivity (low MAb 352, equal and higher MAb 033 and 665) was seen in other baseline samples. In contrast, samples obtained after TRH/GnRH showed immunoreactivity patterns expected for a mixture of 22,000 dalton isoform of GH (22K) with only a small amount of 20K. GH samples obtained during sleep showed both patterns with episodic peaks with equal immunoreactivity superimposed on the basal pattern (decreased activity with MAb 352). Affinity chromatography of basal samples showed that a portion of the GH immunoreactivity was neither 22K nor 20K, although in stimulated samples, over 70% of GH was 22K or 20K GH. In conclusion, the nature of GH isoforms present in serum varies with GH concentration. These differences may contribute to the known difficulty in correlating disease activity and random GH measurements in patients with GH secreting adenomas.
Child↗
The effect of growth hormone treatment on stature in Aarskog syndrome.
We describe 19 males with Aarskog syndrome who were treated with growth hormone (GH) and enrolled in the National Cooperative Growth Study (NCGS). There was a significant increase in both growth rate (3.9 +/- 1.9 cm/yr vs 8.9 +/- 1.7 cm/yr, p < 0.001) and height SD score (change in HtSDS = 1.0 +/- 0.8). The increase in HtSDS was dependent on treatment duration, frequency of injections, weight-for-height SDS, and HtSDS at enrollment. The results of our study suggest a positive effect of GH treatment on growth and adult height in Aarskog syndrome patients.
Adolescent↗
A sensitive method for detection of circulating forms of human growth hormone by immunoautoradiography.
Several different forms of hGH have been isolated from the pituitary, but little is known about modifications of synthesized forms that may exist in the circulation. We used a combination of serum immunoextraction with gel electrophoresis and electrophoretic blotting to detect circulating hGH isohormones. Three different components were identified, with the predominant form being 22,000 MW isomer. The method is sensitive to nanogram quantities of hGH and is applicable to the screening of human serum for the presence of variants of hGH.
Autoradiography↗
Testing cord blood human chorionic gonadotropin as a surrogate marker for early identification of human immunodeficiency virus-1 infection in children.
We measured human chorionic gonadotropin (hCG) in cord sera of 22 infants born to women infected with the human immunodeficiency virus-1 (HIV-1). hCG was also determined in cord sera from 173 infants born at a suburban hospital to HIV-1-seronegative women. The findings indicate that 16 (9%) of 173 HIV-1-seronegative samples had hCG levels greater than 90 IU/L (values were distributed as a Poisson curve). In contrast, 8 (36%) of the 22 infants born to HIV-1-infected women had hCG levels in excess of 90 IU/L, and 7 (88%) of these were shown to be HIV-infected. The remaining 14 infants born to HIV-1-infected women had low hCG levels, and 3 (21%) of the 14 had HIV infection. Mean follow-up time for HIV-uninfected infants was 17.5 months (range 9 months to 3 years). A statistically significant association between maternal-fetal HIV-1 transmission and hCG levels > or = 90 IU/L in cord sera was observed (p = 0.02). The difference between CD4 counts among mothers who transmitted HIV and those who did not was also statistically significant (p = 0.025). On the basis of this study's findings, we propose that cord blood hCG may serve as a surrogate marker for HIV-1 infection. Testing hCG levels in cord sera is an inexpensive and readily available screening test for early identification of infants at increased risk for getting HIV-1 from their mothers.
Biomarkers↗