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R J Robbins

Publications and source records attributed to R J Robbins.

80 records · Page 5Linked to original sources
PubMed1978

Poison-based taste aversion learning in deer mice (Peromyscus maniculatus bairdi).

A series of experiments tested the ability of mice of the native genus Peromyscus to form learned taste aversions. It was found that (a) the mice acquired a strong aversion after a single flavor/toxicosis pairing, (b) naive mice drinking a LiCl solution apparently began to experience toxic effects within 90 sec after the beginning of consumption, (c) the mice acquired a total aversion after a single flavor/delayed illness pairing when high doses of toxin were employed, and (d) the aversion produced by a single flavor/delayed-illness pairing was specific to the flavor paired with illness and was dependent on the contingency between the flavor and illness. Although these responses are qualitatively similar to those reported for domestic rats, the mice formed considerably weaker aversions than those previously reported for laboratory rats tested with the same weight-specific doses of LiCl.

Animals↗
PubMed1978

Nonexponential fluorescence decay of aqueous tryptophan and two related peptides by picosecond spectroscopy.

Time-resolved fluorescence spectroscopy of tryptophan and two related dipeptides, tryptophylalanine and alanyltryptophan, has been carried out on the subnanosecond time scale by using picosecond exciting pulses at a wavelength of 264 nm. Detection was with an ultrafast streak camera coupled to an optical multichannel analyzer. The zwitterions of these molecules show a definite nonexponential fluorescence decay which can be analyzed in terms of two exponentials. The two decay rates increase strongly with increasing temperature, as does the weight of the faster component. In tryptophan at pH 11, where the amino group is deprotonated, there remains only a single temperature-dependent exponential. The results are interpreted in terms of two kinds of trapped conformers in the excited state that interconvert no quicker than the time scale of the fluorescence. A model is suggested in which the nonradiative processes in one conformer approximate those in the bare indole moiety. The nonradiative decay rate of the other conformer is substantially faster. It is believed that the process responsible for this fast decay is intramolecular electron transfer from the indole to the amino acid side chain. The predilection for this electron transfer depends on steric relationships as well as on the electron-attracting power of the carbonyl group. This picture is consistent with earlier fluorescence quantum yield results. In fact, a self-consistent picture emerges from the temporal and yield data that quantitatively explains most important facets of tryptophan photochemistry in aqueous solution.

Journal Article↗
PubMedDate not supplied

Blonde, a new mutation in Peromyscus maniculatus affecting fur, skin, and eye pigmentation.

An autosomal recessive mutation affecting hair and eye pigmentation was discovered in the F2 progeny of wild-type deer mice, (Peromyscus maniculatus), trapped near East Lansing, Michigan. When homozygous, the mutation (designated as blonde, bl), reduces both black and yellow pigmentation deposited in the fur, reduces or eliminates pigmentation in the non-follicular melanocytes of the outer ear, peri-orbital skin and tail, slightly reduces the amount of pigmentation in the choroidal melanocytes, and completely eliminates pigmentation of the retinal epithelium.

Animals↗
PubMedDate not supplied

Giant-cell granulomatous hypophysitis.

OBJECTIVE: To describe the clinical features of giant-cell granulomatous hypophysitis and to report on the results of corticosteroid treatment. METHODS: A case of giant-cell granulomatous hypophysitis is presented, and the pertinent literature is reviewed. RESULTS: A 41-year-old woman with anterior pituitary dysfunction had a pituitary mass that was 18 by 16 by 13 mm by magnetic resonance imaging. The pituitary stalk was thickened and enhanced after intravenous administration of gadolinium. A biopsy specimen that was obtained at transsphenoidal pituitary exploration revealed that the patient had giant-cell granulomatous hypophysitis, a rare inflammatory pituitary disorder. High-dose corticosteroid therapy failed to reverse her anterior pituitary dysfunction. CONCLUSION: The coincidence of a contrast-enhancing pituitary mass with a thickened pituitary stalk and the awareness of the rare occurrence of endocrine inactive tumors in women of childbearing age should suggest an inflammatory pituitary condition. Such lesions should also be suspected in otherwise healthy young women with hypopituitarism and no evidence of hormone hypersecretion. On the basis of the literature and our experience, corticosteroid treatment does not seem to improve anterior pituitary function.

Journal Article↗
PubMedDate not supplied

Radioiodine treatment of thyroid cancer with the aid of recombinant human thyrotropin.

OBJECTIVE: To update endocrinologists on the use of recombinant human thyrotropin (thyroid-stimulating hormone or TSH) (rhTSH) in thyroid diseases, with an emphasis on thyroid cancer. METHODS: We reviewed the available literature on potential uses of rhTSH, including published studies and case reports. RESULTS: Clinical trials have shown that rhTSH injections stimulate radioiodine uptake into normal and malignant thyroid tissue almost as well as that found in the hypothyroid state. The benefit to the athyreotic patient is the avoidance of the disability of hypothyroidism. When rhTSH is used in the doses currently recommended for scanning, few negative side effects occur. The more rapid clearance of iodine in the euthyroid state, however, may necessitate the use of more radioiodine to achieve the same amount of irradiation to metastatic lesions. We have used rhTSH for both dosimetric studies and therapy. This approach is essential in patients who cannot make sufficient endogenous TSH (because of hypothalamic-pituitary disease or medications that suppress TSH). Other patients with widespread metastatic lesions who have serious complications when allowed to become hypothyroid also benefit from rhTSH. Finally, we have found that rhTSH may provide new insights into the biologic features of thyroid cancer when used in combination with positron emission tomographic scanning. Use in the treatment of nonmalignant thyroid conditions such as toxic multinodular goiter is also feasible. CONCLUSION: Overall, rhTSH provides a new and clinically important advance for patients with thyroid disease, especially thyroid cancer.

Journal Article↗
PubMedDate not supplied

Compassionate use of recombinant human thyrotropin to facilitate radioiodine therapy: case report and review of literature.

OBJECTIVE: To describe the use of recombinant human thyrotropin (thyroid-stimulating hormone) (rhTSH) to assist in radioiodine therapy in a patient with thyroid carcinoma who was unable to produce sufficient endogenous thyrotropin when hypothyroid and to review the related literature. METHODS: The study patient underwent formal dosimetric analysis and received radioiodine in conjunction with rhTSH. Follow-up scanning studies were performed. RESULTS: We found good localization of radioiodine on the posttherapy scans after administration of (131)I while the patient continued to receive thyroxine replacement after two intramuscularly administered injections of rhTSH. Some of his metastatic lesions disappeared and his serum thyroglobulin level decreased after the first rhTSH-assisted dose of (131)I was administered. His blood radioiodine clearance rate was unexpectedly more rapid in the hypothyroid state than when he was euthyroid (taking thyroxine) after administration of rhTSH. His whole-body clearance rate was more delayed when he was hypothyroid. Swelling of some of the metastatic thyroid cancer lesions developed when the patient was hypothyroid and after rhTSH was administered, the latter being much more rapid in onset. CONCLUSION: Therapeutic doses of radioiodine can be delivered with the assistance of rhTSH administration while patients continue to take suppressive doses of thyroxine. Metastatic thyroid carcinoma lesions can swell rapidly after administration of rhTSH. The commercially available form of rhTSH is approved only for diagnostic use. Its safety and efficacy in assisting radioiodine therapy have not been fully determined.

Adenocarcinoma, Follicular↗
PubMedDate not supplied

Coat color genetics of Peromyscus: IV. Variable white, a new dominant mutation in the deer mouse.

The variable white mutation arose spontaneously in 1983 within a laboratory stock of wild-type deer mice (Peromyscus maniculatus). The original mutant animal was born to a wild-type pair that had previously produced several entirely wild-type litters. Other variable white animals were bred from the initial individual. Variable white deer mice exhibit extensive areas of white on the head, sides, and tail. Usually a portion of pigmented pelage occurs dorsally and on the shoulders, but the extent of white varies from nearly all white to patches of white on the muzzle, tip of tail, and sides. The pattern is irregular, but not entirely asymmetrical. Eyes are pigmented, but histologically reveal a decrease in thickness and pigmentation of the choroid layer. Many variable white animals do not respond to auditory stimuli, an effect that is particularly evident in animals in which the head is entirely white. Ataxic behavior is also prevalent. Pigment distribution, together with auditory and retinal deficiencies, suggests a neural crest cell migration defect. Breeding data are consistent with an autosomal semidominant, lethal mode of inheritance. The trait differs from two somewhat similar variants in Peromyscus: from dominant spot (S) in extent and pattern of pigmentation and from whiteside (ws), an autosomal recessive trait, in the mode of inheritance and viability. Evidence for possible homology with the Va (varitint-waddler) locus in house mouse (Mus) is presented. The symbol Vw is tentatively assigned for the variable white locus in Peromyscus.

Animals↗