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Biomedical subjects

J Blake

Publications and source records attributed to J Blake.

At least 127 records · Page 7Linked to original sources
PubMed1979

Adrenocorticotropin. 52 Synthesis and biological activity of adrenocorticotropic peptides with cystine bridges.

Three analogs of the amino terminal nonadecopeptide of adrenocorticotropin which incorporate cystine cystine bridges between positions (5, 10), (3, 10), or (2, 10) have been synthesized. All of the peptide analogs showed reduced biological activity; however, the peptide with the 5, 10 cystine bridge was shown to possess significantly higher lipolytic activity in rat fat cells than the peptides with a 3, 10 or 2, 10 cystine bridge.

Adrenal Glands↗
PubMed1979

Use of cyclopentyl ester protection for aspartic acid to reduce base catalyzed succinimide formation in solid-phase peptide synthesis.

A study was conducted to determine the effect of amino acid sequence and aspartyl protecting group on the rate of base catalyzed succinimide formation in the solid-phase synthesis of aspartyl peptides. The peptides H-Ala-Asp-Gly-Phe-OH and H-Ala-Asp-Leu-Phe-OH were synthesized by the solid-phase method with cyclopentyl or benzyl protection for the beta-carboxyl of aspartic acid. The results showed that the cyclopentyl ester was notably less susceptible to succinimide formation by treatment with tertiary amine than was the benzyl ester, and that the difference could have significant consequences for the synthesis of the large peptides which contain reactive sequences such as Asp-Gly.

Amino Acid Sequence↗
PubMed1979

Synthesis of biological activity of human beta-endorphin analogs with disulfide bridges.

Three analogs of human beta-endorphin containing internal cystine bridges have been synthesized and their biological activities have been determined. It was found that the analogs with disulfide bridges between positions 17 and 26 or 11 and 26 retained full opiate activity as estimated by guinea ileum assay, whereas the analog with a cystine bridge between positions 7 and 26 showed reduced opiate activity. None of the analogs retained significant immunoactivity as revealed by radioimmunoassay.

Amino Acid Sequence↗
PubMed1979

Serum triiodothyronine and other clinical and laboratory indices of alcoholic liver disease.

Admission serum triiodothyronine (T3) values in 124 patients hospitalized for alcoholic liver disease were correlated with clinical and laboratory indices of liver function and commonly used determinants of thyroid function. Patients with low admission serum T3 levels had significant alterations in serum albumin, bilirubin, prothrombin time, and alkaline phosphatase associated with clinical signs of portal hypertension and collateral circulation, with little difference in serum glutamic-oxaloacetic transaminase, serum gamma glutamyl transpeptidase, or serum ornithine carbamyl transferase. This group also had a significant decrease in free T3 index despite an increase in T3 uptake; the slight reduction in total thyroxine (T4) was associated with an increase in free T4 index and no change in serum thyrotropin (TSH). For patients with alcoholic liver disease, low admission serum T3 and free T3 index values when accompanied by normal serum T4, free T4 index, and TSH levels appear to be indicative of severe liver dysfunction and increased mortality risk.

Humans↗
PubMed1979

Effect of short-term therapy with propylthiouracil in patients with alcoholic liver disease.

The effect of propylthiouracil (PTU; 300 mg/day) on alcoholic liver disease was evaluated in 133 patients in a short-term randomized double-blind trial. Severity of the disease was assessed by a composite clinical and laboratory index (CCLI). A normalization rate (NR) representing the rate of improvement in CCLI was calculated. Patients with alcoholic hepatitis, with and without cirrhosis, showed a significantly higher NR on PTU (43.6 +/- 4.6) than on placebo (19.8 +/- 3.3; P less than 0.001). A similar effect was observed in patients with abnormal prothrombin (no biopsy): NR was 32.9 +/- 6.9 on PTU and 2.6 +/- 3.7 on placebo (P less than 0.005). The effect of PTU on each clinical and laboratory component of the CCLI was also compared in these two groups. In 38 patients with alcoholic hepatitis and in 25 with abnormal prothrombin, those on PTU showed a greater improvement in 15 of 15 items (P less than 0.001) and 14 of 15 (P less than 0.01), respectively. When patients were divided according to the severity of the disease into those in the lower and upper halves of the CCLI range (81 and 52 patients, respectively), PTU was shown to have a significant effect only in the latter: The NR was 41.4 +/- 3.8 on PTU and 22.5 +/- 4.2 on placebo (P less than 0.005). PTU was ineffective in patients with inactive cirrhosis.

Double-Blind Method↗
PubMed1979

Thyroid hormones in alcoholic liver disease. Effect of treatment with 6-n-propylthiouracil.

The relationship between alcoholic liver disease and circulating thyroid hormones was investigated in 124 hospitalized patients treated with placebo or propylthiouracil (PTU) for a maximum of 46 days in a double-blind study. Serum triiodothyronine (T3) levels on admission were significantly (P less than 10(-6) and inversely correlated with the severity of alcoholic liver disease. After hospitalization, changes in T3-levels in patients with low admission T3 significantly correlated (P less than 0.001) with the degree of spontaneous improvement of liver function (placebo group). Treatment with 300 mg of PTU daily (Orrego et al. Gastroenterology 76:105--115, 1979) markedly increased the rate of improvement in severely ill patients with low T3 on admission. In this group, serum T3-levels were also increased after PTU, but this increase did not correlate with the change in the patient's condition. It is suggested that the known inhibitory effect of PTU on peripheral deiodination of T4 to T3 is marked by a more marked improvement in liver function in this group. PTU treatment in this group reduced the free T4-index and increased TSH levels markedly (16%; P less than 0.02) toward levels found in hypothyroidism. PTU did not improve the condition of mildly ill patients with normal admission T3-levels, nor did it alter free T4-index or serum TSH levels in these patients. Serum T3-levels provide a sensitive indicator of the severity of alcoholic liver disease and of its response to conventional treatment. Serum T3-levels also distinguish between a group of patients, in whom low-dose PTU administration results in a beneficial effect, and another group, in whom no therapeutic effect of PTU is observed.

Humans↗
PubMed1978

Human somatotropin. 55. Synthesis and growth-promoting activity of peptide analogs of the carboxyl terminal plasmin fragment.

Three analogs of the carboxyl terminal plasmin fragment of human somatotropin, [Nle 170, Ala165, 182, 189]-human somatotropin-(145-191), [Nle170, Ala165, 182, 189]-human somatotropin-(140-191), and [Lys135,136, 138, Glu137, 139, Nle170, Ala165, 182, 189]-human somatotropin-(135-191) have been synthesized by the solid-phase method. The synthetic peptides were assayed for growth-promoting activity and their potency was found to be comparable to that of [S-carbamideomethylcysteine165,182, 189]-human somatotropin-(141-191) which was derived from the native hormone.

Amino Acid Sequence↗
PubMed1977

Treatment of herpetic keratitis.

Idoxuridine which was first used in 1960 (Kaufman et al., 1962), has been for many years the only antiviral agent available in the treatment of herpetic keratitis. It is however no more successful than is mechanical removal of diseased epithelium (Patterson & Jones, 1967), and furthermore it may give rise to serious toxic side effects. The search for an alternative medication is therefore a pressing one. Trifluorothymidine (F3T) has, in recent years, been shown to be more effective than IDU and to be free from significant toxicity. Both of these drugs are pyrimidine nucleosides. Adenine Arabinoside or Arabinoside-A (Ara-A) is, by contrast, a purine nucleoside. It is thought to exert its antiviral effect by blocking DNA polymerase and ribonucleotide reductase.

Drug Evaluation↗
PubMed1977

Human somatotropin: restoration of full biological activity by noncovalent interaction of a natural and a synthetic fragment of the hormone.

The recombinant hormone obtained by noncovalent interaction of the natural NH2-terminal fragment (consisting of 134 amino acid residues) with a synthetic COOH-terminal fragment of 52 amino acids of the reduced-carbamidomethylated human somatotropin molecule is found to exhibit full biological activity of the native hormone as evidenced by the tibia test. Radioimmunoassay data indicate that the semisynthetic recombinant hormone possesses essentially full immunoreactivity as compared to the native one. In addition, circular dichroism and fluorescence emission spectra of the semisynthetic recombinant are identical to that of the undisociated, plasmin modified, reduced-carbamidomethylated hormone.

Biological Assay↗
PubMed1976

Adrenocorticotropin. 49.1 Synthesis and biological activity of [2-delta-aminovaleric acid, 5-arginine-a1adrenocorticotropin-(2-19).

An adrenocorticotropin analogue, [2-delta-aminovaleric acid, 5-arginine]adrenocorticotropin-(2-19), has been synthesized by the solid-phase method and its biological activity has been determined. It was found that substitution of arginine for glutamic acid at position 5 of [2-delta-aminovaleric acid]adrenocorticotropin-(2-19) increased the steroidogenic potency in idolated rat adrenal cells and the lipolytic potency in isolated rat fat cells but decreased the lipolytic potency in isolated rabbit fat cells. The synthetic analogue had only 2% of the melanotropic potency of the parent molecule.

Adipose Tissue↗
PubMed1976

Adrenocorticotropin. 48. Synthesis and biological activity of (15, 16-D-lysine, 17, 18-D-arginine)-adrenocorticotropin-(1-19) and an all-D-retropeptide related to the amino terminal octadecapeptide of adrenocorticotropin.

The peptide [15, 16-D-lysine, 17, 18-D-arginine]-adrenocorticotropin-(1-19) and an all-D-retropeptide related to the amino terminal octadecapeptide of adrenocorticotropin have been synthesized by the solid-phase method. The nonadecapeptide was shown to possess 10-15% of the steroidogenic activity and 3% of the lipolytic activity of adrenocorticotropin-(1-19). The all-D-retropeptide showed no activity and exhibited no inhibitory activity in steroidogenesis and lipolysis.

Adrenocorticotropic Hormone↗