Hydrocephalus in Maroteaux-Lamy syndrome.
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Child↗
Biomedical subjects
G P Schwartz
Publications and source records attributed to G P Schwartz.
Survey of 520 eyes with uveal metastases.
OBJECTIVE: The purpose of this investigation is to report the clinical features of patients with uveal metastases seen at a major ocular oncology center. DESIGN/PARTICIPANTS: A retrospective chart review was performed on all patients with uveal metastases evaluated at an ocular oncology outpatient facility over a 20-year period. MAIN OUTCOME MEASURE: To assess the systemic and ophthalmic features of uveal metastases. RESULTS: A total of 950 uveal metastases were diagnosed in 520 eyes of 420 consecutive patients. Of the 950 metastatic foci, the uveal involvement included iris in 90 (9%), ciliary body in 22 (2%), and choroid in 838 (88%). The total number of uveal metastases per eye was 1 (71%) in 370 eyes, 2 (12%) in 63 eyes, and 3 or more (17%) in 87 eyes. The mean number of uveal metastases per eye was two (median, one). Iris metastases presented most often as a yellow-to-white solitary nodule in the inferior quadrant. Ciliary body metastases typically presented as a solitary, sessile, or dome-shaped yellow mass in the inferior quadrant, but were difficult to visualize directly. The choroidal metastases typically were yellow in color, plateau shaped, and associated with subretinal fluid. In the 479 eyes with choroidal metastases, the epicenter of the main tumor was found in the macular area in 59 eyes (12%), between the macula and equator in 383 eyes (80%), and anterior to the equator in 37 eyes (8%). The mean size of the main (largest) choroidal tumor in each eye was 9 mm in base and 3 mm in thickness. At the time of ocular diagnosis, 278 patients (66%) reported a history of a primary cancer and 142 patients (34%) had no history of a cancer. Subsequent evaluation of these 142 patients after the ocular diagnosis of uveal metastasis showed a primary tumor in the lung in 50 patients (35%), breast in 10 (7%), others in 9 (6%), and no primary site was found in 73 patients (51%). Nearly half of the patients with no known primary site eventually died of diffuse metastatic disease. In the entire group of 420 patients, the uveal metastasis came from a primary cancer of the breast in 196 (47%), lung in 90 (21%), gastrointestinal tract in 18 (4%), kidney in 9 (2%), skin in 9 (2%), prostate in 9 (2%), and other cancers in 16 (4%). In 73 cases (17%), the primary site was never established despite systemic evaluation by medical oncologists. CONCLUSIONS: Iris, ciliary body, and choroidal metastases have typical clinical features that should suggest the diagnosis. The choroid is the most common site for uveal metastases, and the tumors occur most often in the posterior pole of the eye with an average of two tumors per eye. Approximately one third of patients have no history of primary cancer at the time of ocular diagnosis. Breast and lung cancers represent more than two thirds of the primary tumor sites.
Aged↗
5-Hydroxytryptophan: an absorption and fluorescence probe which is a conservative replacement for [A14 tyrosine] in insulin.
Use of insulin's intrinsic tyrosine absorption and fluorescence to monitor its interaction with the insulin receptor is limited because the spectral properties of the receptor tryptophan residues mask the spectral properties of the hormone tyrosine residues. We describe the synthesis of an insulin analog where A14 tyrosine is replaced by a tryptophan analog, 5-hydroxytryptophan. This insulin is spectrally enhanced since 5-hydroxytryptophan has an absorption band above 300 nm which is at lower energies than the absorption of tryptophan. Steady-state and time-resolved fluorescence parameters indicate that 5-hydroxytryptophan reports the same information about the environment of the A14 side chain as does the corresponding tryptophan-containing insulin. The synthetic hormone is a full agonist compared to porcine insulin, but has slightly reduced specific activity. Consequently, this spectrally enhanced insulin analog will be useful for hormone-receptor interaction studies since it can be observed by both absorption and fluorescence even in the presence of the tryptophan-containing receptor.
5-Hydroxytryptophan↗
Cross-linking of a B25 azidophenylalanine insulin derivative to the carboxyl-terminal region of the alpha-subunit of the insulin receptor. Identification of a new insulin-binding domain in the insulin receptor.
To identify a site within the insulin receptor ectodomain which forms a binding pocket for B25 Phe and is responsible for initiating conformational changes required for high affinity binding of insulin we have used a novel photoreactive insulin, despentapeptide-(B26-B30) [B25 p-azidophenylalanine-alpha-carboxamide] insulin (APC insulin). This derivative has a highly photoreactive azido group incorporated into the aromatic ring of the B25 phenylalanine amide. APC insulin bound to human insulin receptors overexpressed on a transfected Chinese hamster ovary cell line (P3-A) with an apparent potency of 9-fold relative to that of native insulin and stimulated lipogenesis in rat adipocytes with an average potency equal to porcine insulin. Addition of biotin to the B1 Phe amino group to form despentapeptide-(B26-B30) [B1 (6-biotinylamidocaproyl)phenylalanine B25 p-azidophenylalanine-alpha-carboxamide] insulin derivative (Bio-APC insulin) did not adversely affect receptor-binding affinity and provided a convenient ligand for purification of cross-linked complexes. The efficiency of receptor cross-linking with these reagents was high (70%). To identify the site(s) of cross-linking, the insulin receptor in P3-A cells was first metabolically labeled with various individual 3H-labeled amino acids and then photoaffinity labeled with 125I-Bio-APC insulin, isolated, and digested with Lys-C endoproteinase. The resulting cross-linked peptide fragments were separated by streptavidin-affinity chromatography and sequenced. The smallest identified fragment comprised residues 704-718 of the COOH terminus of the alpha-subunit of the insulin receptor. This B25 Phe cross-linked region of the alpha-subunit lies just upstream of the Exon 11-encoded 12-amino acid COOH-terminal region. Aromatic residues in this predicted alpha-helical region may form a binding pocket for B25 Phe to initiate conformational changes required for stabilizing the high affinity binding state.
Affinity Labels↗
Determination of the tryptophan:tyrosine ratio in proteins.
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Amino Acid Sequence↗
Steric requirements at position B12 for high biological activity in insulin.
The alpha-helix formed by the amino acid residues 9-19 of the B-chain of insulin is involved in the stabilization of its three-dimensional structure. We have shown that modification at positions B9, B10, B12, and B16 results in analogues possessing biological activities ranging from ca. 0.2% to ca. 500% relative to that of natural insulin. The lowest potency was displayed by [B12 Asn]insulin, in which the hydrophobic B12 Val residue was replaced by the hydrophilic Asn residue. We now report the synthesis of four insulin analogues in which hydrophobicity is retained, and only the spatial arrangement of atoms in the B12 region is altered. Substitution of B12 Val with alpha-aminoisobutyric acid (Aib), D-Ala, and Phe led to analogues possessing biological activities, in lipogenesis assays, of 8.5%, 2%, and 0.2%, respectively, relative to that of natural insulin. Inversion of the B11-B12 sequence, -Leu-Val-, led to an analogue displaying 3.3% activity. A synthetic B-chain in which the B11 Leu-B12 Val sequence was replaced by B11 Ala-B12 Ile was incapable of combining with the natural A-chain. We conclude that the Val residue in the B12 position in insulin fulfills special side-chain packing requirements involved in the stability of the structure of insulin. Even slight steric alteration at position B12 results in a distortion of the overall conformation of the B-chain which affects its ability to combine with the natural A-chain. This distortion is retained in the corresponding analogue, which is reflected in diminished biological potency.
Amino Acid Sequence↗
Correlation of tryptophan fluorescence intensity decay parameters with 1H NMR-determined rotamer conformations: [tryptophan2]oxytocin.
While the fluorescence decay kinetics of tyrosine model compounds [Laws, W. R., Ross, J. B. A., Wyssbrod, H. R., Beechem, J. M., Brand, L., & Sutherland, J. C. (1986) Biochemistry 25, 599-607] and the tyrosine residue in oxytocin [Ross, J. B. A., Laws, W. R., Buku, A., Sutherland, J. C., & Wyssbrod, H. R. (1986) Biochemistry 25, 607-612] can be explained in terms of heterogeneity derived from the three ground-state chi 1 rotamers, a similar correlation has yet to be directly observed for a tryptophan residue. In addition, the asymmetric indole ring might also lead to heterogeneity from chi 2 rotations. In this paper, the time-resolved and steady-state fluorescence properties of [tryptophan2]oxytocin at pH 3 are presented and compared with 1H NMR results. According to the unrestricted analyses of individual fluorescence decay curves taken as a function of emission wavelength and a global analysis of these decay curves for common emission wavelength-independent decay constants, only three exponential terms are required. In addition, the preexponential weighting factors (amplitudes) have the same relative relationship (weights) as the 1H NMR-determined chi 1 rotamer populations of the indole side chain. 15N was used in heteronuclear coupling experiments to confirm the rotamer assignments. Inclusion of a linked function restricting the decay amplitudes to the chi 1 rotamer populations in the individual decay curve analyses and in the global analysis confirms this correlation. According to qualitative nuclear Overhauser data, there are two chi 2 populations. Depending upon the degree of correlation between chi 2 and chi 1, there may be from three to six side-chain conformations for the tryptophan residue. The combined fluorescence and NMR results are consistent with a rotamer model in which either (i) the chi 2 rotations are fast compared to the fluorescence intensity decay of the tryptophan residue, (ii) environmental factors affecting fluorescence intensity decay properties are dominated by chi 1 interactions, or (iii) the chi 2 and chi 1 rotations are highly correlated.
Amino Acid Sequence↗
Neurophysin-neurohypophyseal hormone interactions: studies using a dansylated vasotocin analogue.
We have synthesized a neurohypophyseal hormone analogue containing an extrinsic fluorescence probe by linking a dansyl (DNS) group to the epsilon-amino group of the lysine at residue 8 of vasotocin. The fluorescence properties of this analogue have been characterized by steady-state and time-resolved spectroscopic methods and compared with those of epsilon-DNS-lysine and the dansylated carboxyl terminal tripeptide Pro-Lys(DNS)-GlyNH2. The binding of this hormone analogue to purified isoforms of bovine neurophysins, the natural carrier proteins of the neurohypophyseal hormones, results in changes in several fluorescence parameters of the dansyl probe. These changes include an increase in intensity and average lifetime, a shift of the emission band to higher energies, and an increase in the emission anisotropy. Anisotropy changes have been used to determine dissociation constants for binding to these neurophysin isoforms. Based on the changes in the fluorescence properties of the dansyl probe, the dansyl group itself interacts with the protein. The degree of the dansyl-neurophysin interaction, however, appears to be different for the full sequence isoform of neurophysin I and the Val89 isoform of neurophysin II.
Amino Acid Sequence↗
Superactive insulins.
The substitution of aspartic acid for the naturally-occurring histidine residue in position B10 in human insulin results in an insulin analogue which displays an in vitro potency 4- to 5-fold greater than the parent compound. This substitution has been introduced into six insulin analogues which, before modification, display potencies ranging from less than 0.01-fold to 3-fold relative to natural insulin. In each case, the resulting aspartic acid-substituted analogue is substantially more potent than the parent compound. Thus, it is now possible to prepare "tailor-made" insulins with enhanced potency.
Aspartic Acid↗
A highly potent insulin: des-(B26-B30)-[AspB10,TyrB25-NH2]insulin(human).
An insulin analogue that embodies two distinct structural modifications, each of which independently increases insulin activity, has been synthesized and evaluated for biological activity. The analogue, des-(B26-B30)-[AspB10,TyrB25-NH2]insulin is the most potent insulin analogue yet described; it displays an 11- to 13-fold higher activity than natural insulin. The findings are discussed with regard to the receptor-binding domains of insulin.
Adipose Tissue↗
Determinants of growth-promoting activity reside in the A-domain of insulin-like growth factor I.
A two-chain, disulfide linked, insulin-like compound embodying the A-domain of insulin-like growth factor I (IGF-I) and the B-chain of insulin has been synthesized and characterized with respect to insulin-like biological activity and growth-promoting potency. The compound displays a potency of ca. 41% relative to insulin in assays for insulin-like activity (e.g., lipogenesis) but significantly higher activity than insulin, ca. 730% relative to insulin, in growth factor assays (e.g., thymidine incorporation). The compound is, however, a less potent growth factor than IGF-I itself, ca. 26.5% relative to IGF-I, and is not recognized by IGF carrier proteins. We conclude that structural features contained in the A-domain of IGF-I are primarily responsible for the growth-promoting ability displayed by IGF-I, while features in the B-domain are responsible for recognition by IGF carrier proteins.
Amino Acid Sequence↗
Hybrid molecules containing the A-domain of insulin-like growth factor-I and the B-chain of insulin have increased mitogenic activity relative to insulin.
Two synthetic insulin-like compounds consisting of the B-chain of insulin linked via disulfide bonds to A chains corresponding to the A-domain or the A- and D-domains of insulin-like growth factor I (IGF-I) have been evaluated for mitogenic activity and for binding to IGF receptors and IGF carrier proteins. Both compounds are 3- to 5-fold more potent mitogens than insulin, and have a comparably increased affinity for the type I IGF receptor that mediates these mitogenic effects in chick embryo fibroblasts. Neither compound interacts with IGF carrier proteins. These results indicate that the A-domain of IGF-I is importantly involved in its growth-promoting properties.
Animals↗
A superactive insulin: [B10-aspartic acid]insulin(human).
The genetic basis for a case of familial hyperproinsulinemia has been elucidated recently. It involves a single point mutation in the proinsulin gene resulting in the substitution of aspartic acid for histidine-10 of the B chain of insulin. We have synthesized a human insulin analogue, [AspB10]insulin, corresponding to the mutant proinsulin and evaluated its biological activity. [AspB10]Insulin displayed a binding affinity to insulin receptors in rat liver plasma membranes that was 534 +/- 146% relative to the natural hormone. In lipogenesis assays, the synthetic analogue exhibited a potency that was 435 +/- 144% relative to insulin, which is statistically not different from its binding affinity. Reversed-phase HPLC indicated that the synthetic analogue is more apolar than natural insulin. We suggest that the observed properties reflect changes in the conformation of the analogue relative to natural insulin, which result in a stronger interaction with the insulin receptor. Thus, a single substitution of an amino acid residue of human insulin has resulted in a superactive hormone.
Animals↗
An insulin analogue possessing higher in vitro biological activity than receptor binding affinity. [21-Proline-B]insulin.
To study the effect of an increase in the potential for beta-turn formation of the B20-B23 segment of the B-chain moiety on the biological behavior of insulin, the [21-proline-B]insulin [( Pro21-B]insulin) was synthesized. The in vitro biological activity and the receptor binding affinity of this analogue were compared with that of insulin. In stimulating labeled glucose incorporation into lipids in rat fat cells, the analogue displayed 33.2% potency relative to insulin; receptor binding affinity for the analogue was 15.9% in rat liver membranes and 17.8% in isolated fat cells. [Pro21-B]insulin is thus the first example of a modified insulin for which the biological activity exceeds the receptor binding potency. The secondary structure of this analogue was investigated by circular dichroism studies. Although no significant differences in the conformation of monomeric insulin and analogue could be discerned, their difference in behavior with respect to dimerization and biological properties indicates that these forms are not equivalent. We suggest that the intrinsic activity of receptor-bound [Pro21-B]insulin is greater than that of insulin, although the receptor displays greater affinity for insulin than for the analogue. We consider a model for the interaction between insulin and its receptor that accommodates our findings.
Adipose Tissue↗
[12-asparagine-B] human insulin. An analogue with modification in the hydrophobic core of insulin.
The human [12-Asparagine-B] insulin [Asn12-B] insulin) which differs from the parent molecule in that the valine residue at position B12 is substituted by an asparagine residue, has been synthesized by the procedures developed in this laboratory. In stimulating glucose oxidation and lipogenesis the analogue exhibited potencies of 0.19% and 0.14%, respectively, as compared to insulin. In insulin receptor binding [Asn12-B] insulin was found to possess a potency of ca. 0.29% compared to the natural hormone. At high concentrations this analogue is shown to have the same maximal activity in the in vitro assays as the natural hormone. This indicates that despite the low affinity for of the analogue for the insulin receptor, the analogue-receptor complex is fully capable of initiating the series of chemical events that leads to the biological response. It is concluded that the B12 valine contributes greatly in the maintenance of a structure possessing the proper receptor-binding characteristics, but does not have any role in modulating the activity of the hormone-receptor complex. The potency of this analogue by radioimmunoassay is at least 100-fold higher than the in vitro biological assays, indicating that the immunological determinants of insulin can be essentially unrelated to the biological activity of the molecule.
Amino Acid Sequence↗
The synthesis of peptides by homogeneous solution procedures.
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Amino Acid Sequence↗
A synthetic human insulin analogue midified at position B-22. [Lys-22-B] human insulin.
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Amino Acid Sequence↗
Synthesis of a biologically active truncated insulin. Des(pentapeptide B23-30) human (porcine) insulin.
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Amino Acid Sequence↗