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Biomedical subjects

M A Hess

Publications and source records attributed to M A Hess.

32 records · Page 2Linked to original sources
PubMed1997

Taste: the neglected nutritional factor.

Scientists now think that every taste bud has some degree of sensitivity to all the primary taste sensations. The brain detects the type of taste by the ratio of stimulation of different taste buds. Many different substances have flavor-enhancing capacity, including ingredients that represent the primary tastes. Medications, chronic disorders, and radiation therapy can alter taste perception, resulting in loss of appetite. Individualizing nutrition advice, with consideration of taste, health needs, and personal preferences, is a "signature dish" of quality dietetics practice.

Aged↗
PubMed1996

Sequence and structure determinants of Drosophila Hsp70 mRNA translation: 5'UTR secondary structure specifically inhibits heat shock protein mRNA translation.

Preferential translation of Drosophila heat shock protein 70 (Hsp70) mRNA requires only the 5'-untranslated region (5'-UTR). The sequence of this region suggests that it has relatively little secondary structure, which may facilitate efficient protein synthesis initiation. To determine whether minimal 5'-UTR secondary structure is required for preferential translation during heat shock, the effect of introducing stem-loops into the Hsp70 mRNA 5'-UTR was measured. Stem-loops of -11 kcal/mol abolished translation during heat shock, but did not reduce translation in non-heat shocked cells. A -22 kcal/mol stem-loop was required to comparably inhibit translation during growth at normal temperatures. To investigate whether specific sequence elements are also required for efficient preferential translation, deletion and mutation analyses were conducted in a truncated Hsp70 5'-UTR containing only the cap-proximal and AUG-proximal segments. Linker-scanner mutations in the cap-proximal segment (+1 to +37) did not impair translation. Re-ordering the segments reduced mRNA translational efficiency by 50%. Deleting the AUG-proximal segment severely inhibited translation. A 5-extension of the full-length leader specifically impaired heat shock translation. These results indicate that heat shock reduces the capacity to unwind 5-UTR secondary structure, allowing only mRNAs with minimal 5'-UTR secondary structure to be efficiently translated. A function for specific sequences is also suggested.

Animals↗
PubMed1994

RNA/protein interactions in the 5'-untranslated leader of HSP70 mRNA in Drosophila lysates. Lack of evidence for specific protein binding.

We have investigated the hypothesis that preferential translation of the heat stress mRNAs requires the binding of a trans-acting protein factor. 32P-Labeled RNA probes covering the 5'-untranslated region (5'-UTR) of HSP70 mRNA were synthesized, and gel retardation and UV cross-linking assays performed to identify trans-acting sequence-specific RNA-binding factors. The results indicate that no HSP70 5'-UTR RNA-specific binding proteins exist. Reducing the "stringency" in the gel retardation binding analyses revealed several non-sequence-specific RNA-binding complexes. The proteins bind RNA more strongly than DNA, show minor preferences for specific sequences, but none binds more strongly to the HSP70 5'-UTR than to other non-heat stress RNAs. Ultraviolet cross-linking analysis identifies two principal HSP70 5'-UTR binding proteins, of approximately 50 and 70 kDa. The p50 binding activity is increased severalfold for all mRNAs in heat-stressed lysates, and its binding produces the primary gel-retarded complex. Further detailed analyses were performed to probe for any possible heat-influenced changes. RNA/protein interactions are not affected by capping. Neither the kinetics nor the salt sensitivity of protein binding is affected by heat. Binding analyses using partial or complete HSP70 5'-UTR give qualitatively similar conclusions. Binding analyses were also carried out with several "normal" 5'-UTRs to investigate whether a heat-induced repressor might be activated by heating. No normal mRNA-specific heat-induced binding changes are detected. We conclude that heat-induced alterations in RNA-binding proteins do not mediate preferential translation of heat stress mRNAs or repression of normal mRNAs.

Animals↗
PubMed1985

Fibrous bodies in growth hormone-secreting adenomas contain cytokeratin filaments.

Fibrous bodies in growth hormone-secreting adenomas were studied by immunocytochemistry using an anti-cytokeratin antiserum. Fibrous bodies are a feature of acidophil and chromophobe adenomas and are usually associated with acromegaly. Ultrastructural examination revealed round juxtanuclear filamentous aggregates, composed of 8-nm filaments and other organelles. This study demonstrated that the intermediate filaments of fibrous bodies belong to the cytokeratin class. The etiology and significance of these filamentous aggregates remain obscure.

Adenoma↗
PubMed1984

Cytoplasmic filaments of Crooke's hyaline change belong to the cytokeratin class. An immunocytochemical and ultrastructural study.

Crooke's hyaline change was studied by immunocytochemistry using an anti-adrenocorticotropic hormone (ACTH) antiserum and five different antisera against cytokeratins. Crooke's hyaline appears in basophil cells of the adenohypophysis in patients with hypercortisolism, presumably as a part of the negative feedback on corticotropin secretion. Previous studies have identified the hyaline material as a simple protein, apparently unrelated to ACTH, and electron microscopy has revealed a loss of secretory granules and an accumulation of 6-9-nm filaments in the cytoplasm of affected cells. In this study, the secretory granules in adenohypophysial cells exhibiting Crooke's hyaline change were labeled by anti-ACTH antibodies, while the hyaline material was positive for cytokeratin with each of the five antisera used. The results suggest that high levels of glucocorticoids may stimulate elaboration of cytokeratins in basophils while they suppress the production and release of ACTH.

Adenoma, Basophil↗