Nutrition in cancer: an overview.

OBJECTIVES: To provide a review of weight loss, cachexia (both primary and secondary), and weight gain in cancer patients. DATA SOURCES: Research reports, review articles, textbooks, and personal communications. CONCLUSIONS: Alterations in nutritional status have the potential to affect mortality, morbidity, and quality of life outcomes. The detection and treatment of malnutrition is important to success of therapy. IMPLICATIONS FOR NURSING PRACTICE: Nursing interventions to help maintain optimal nutritional status in patients with cancer include careful assessment, identification of patients at risk, and management of problems before the initiation of therapy.

Nutrition as a component of alternative therapy.

OBJECTIVES: To discuss common "alternative" nutritional strategies that may be used by patients as a primary or adjunctive means of cancer treatment. DATA SOURCES: Government reports, textbook chapters, published articles, and research reports. CONCLUSIONS: The use of diet and nutrition to prevent and treat disease is one of six fields of alternative medicine. A number of dietary regimens have been purported to be effective in the treatment of cancer. Most have been inadequately tested with regard to safety and efficacy. IMPLICATIONS FOR NURSING PRACTICE: Oncology nurses need to be knowledgeable of the use of alternative methods so that they may provide accurate information to patients considering these approaches.

Metastases that interfere with circulation.

OBJECTIVES: To review the nursing implications of select circulatory problems caused by metastatic cancer. DATA SOURCES: Journal articles, research studies, and book chapters relating to circulatory problems associated with metastatic disease. CONCLUSIONS: During the metastatic process, tumor cells can interfere with circulation. As a result, circulatory impairments can range from life threatening to manifestations that may alter a person's quality of life. IMPLICATIONS FOR NURSING PRACTICE: Oncology nurses have a responsibility to seek current knowledge about therapeutic and supportive care for persons experiencing circulatory alterations. Collaboration with colleagues can facilitate patient care in these clinical situations. Patient education can be supportive and may enhance optimal outcomes.

5-HT3-receptor antagonists: a review of pharmacology and clinical efficacy.

PURPOSE/OBJECTIVES: To review the role of serotonin in chemotherapy-induced emesis and the mechanism by which 5-hydroxytryptamine3 (5-HT3)-receptor antagonists block the action of serotonin; to review the pharmacology and clinical efficacy of the 5-HT3-receptor antagonists in controlling nausea and vomiting induced by highly emetogenic chemotherapy regimens, including a comparison of agents in this class. DATA SOURCES: Journal articles and proceedings of clinical oncology conferences. DATA SYNTHESIS: Prior to the availability of 5-HT3-receptor antagonists, metoclopramide was the therapy of choice for prevention of cisplatin-associated emesis. Several randomized, double-blind, comparative trials have established that a 5-HT3-receptor antagonist used alone is more effective than metoclopramide and equal to or better than the combination of metoclopramide and dexamethasone. CONCLUSION: 5-HT3-receptor antagonists contribute significantly to the current armamentarium of antiemetic agents. Clinical trials consistently have demonstrated a benefit with these agents that exceeds the previously established antiemetic standards. IMPLICATIONS FOR NURSING PRACTICE: 5-HT3-receptor antagonists have had a profound impact on the clinical management of acute chemotherapy-induced nausea and vomiting. Based on their unique mechanism of action and low toxicity profile, the 5-HT3-receptor antagonists offer a relatively new approach to controlling nausea and vomiting associated with highly emetogenic chemotherapy.

A review of peripherally inserted central venous catheters in oncology patients.

The use of semipermanent vascular access devices has become standard in the management of specific clinical populations. Recently, the use of peripherally inserted catheters has gained popularity owing to the relative ease of insertion and lower complication rates.

The role of fibrinolytic agents in the management of thrombotic complications associated with vascular access devices.

VADs have made a significant contribution to improving quality of life for patients requiring long-term therapies. Clearly, this means of vascular access has offered relief from repeated venipuncture for IV access or blood sampling. Reports of the incidence of associated noninfectious complications vary between 14% and 25%. These rates are significant and warrant the development of strategies to manage such events. Fibrinolytic therapy offers a viable option for patients who have developed complications of a thrombotic nature. Although direct IV push administration may be relatively well accepted, many questions remain regarding the delivery of continuous infusions. Questions about dosing regimens, timing and number of administrations, and the ideal route of delivery all provide fertile opportunities for collaborative research.

Hypermodified alkali-stable dinucleotide sequences in each of the high-molecular-weight (26S and 18S) ribosomal RNA species of wheat.

Two hypermodified, alkali-stable dinucleotide sequences, each containing a base modification in addition to sugar methylation, are known to be present in wheat embryo 26S + 18S rRNA (Gray, M.W. (1974) Biochemistry 13, 5453-5463). Quantitative analysis of unfractionated 26S + 18S rRNA had suggested that each of these sequences (Cm-psi p and psi m-Ap, where Cm=O2'-methylcytidine and psi m-O2'-methylpseudouridine) was present in either the 18S or the 26S rRNA species, but not the both, at a frequency of not more than once per chain. In the study reported here, the individual 32P-labeled 18S and 26S rRNA species were isolated from viable wheat embryos germinated in the presence of [32P]orthophosphate. From analyses of phosphodiesterase and alkaline hydrolysates of the separated [32P]RNAs, we conclude that psi m-Ap is confined to wheat cytosol 18S rRNA, whereas Cm-psi p is localized in wheat cytosol 26S rRNA. The presence of psi m in the 18S rRNA of wheat stands in contrast with the situation in animal cells, where this hypermodified nucleoside is located in the 28S rRNA (Khan, M.S.N. & Maden, B.E.H. (1976) J. Mol. Biol. 101, 235-254).

Isolation and characterization of 32P-labeled mitochondrial and cytosol ribosomal RNA from germinating wheat embryos.

With the aim of preparing highly labeled material, the incorporation of [32P]-orthophosphate into mitochondral and cytosol ribosomal RNA was examined in germinating wheat embryos. Nucleic acids were extracted from mitochondria and from post-mitochondrial supernatant (cytosol) prepared from homogenates of viable embryos (8g) imbibed for 24h in a medium containing [32P]orthophosphate (100mCi). High-molecular-weight ribosomal RNA was selectively precipitated in the presence of 3M NaCl and was further resolved on sucrose density gradients and polyacrylamide gels. Both the mitochondrial and cytosol NaCl-insoluble RNA fractions were found to contain two major radioactive components, corresponding to the large (26S) and small (18S)rRNA species. On non-denaturing gels, these species had apparent molecular weights of 1.3 and 0.67 million daltons (cytosol) and 1.3 and 0.75 million daltons (mitochondrial). The individual, purified [32P]rRNA components (isolated from sucrose gradients) had specific activities of 2--3-10(6) cpm/A260 unit, and were suitable for analysis of nucleotide composition and sequence. By hydrolyzing the individual [32P]rRNA specimens with purified snake venom phosphodiesterase and resolving the products by two-dimensional paper chromatography, it was possible to determine the specific activities (cpm/micronmol) of the four major 5'-nucleotide constituents. The results indicated that there had been no differential 32P-labeling of the nuclear and mitochondrial pools of ribonucleoside 5'-triphosphates (rNTP) during the 24 h imbibition period; however, as previously observed in this system (Lau, R.Y., Kennedy, T.D. and Lane, B.G. (1974) Can. J. Biochem. 52, 1110--1123), there had been unequal 32P-labeling of the individual rNTPs in both the mitochondria and nucleus. The relative specific activities of the 5'-nucleotide constituents of the mitochondrial and cytosol rRNA species were essentially the same, and in the order pA congruent to pU greater than pG greater than pC. By making suitable corrections for these differences in specific activity, the nucleotide composition of each of the [32P]rRNA specimens could be calculated...

Wheat embryo mitochondrial 18S ribosomal RNA: evidence for its prokaryotic nature.

We present a catalog of sequences of oligonucleotides produced by T1 ribonuclease digestion of 32P-labeled small-ribosomal-subunit RNA ("18S rRNA) isolated from purified wheat embryo mitochondria. This catalog is compared to catalogs published for prokaryotic and chloroplast 16S rRNAs and to preliminary results for wheat cytosol 18S rRNA. These comparisons indicate that: (1) wheat mitochondrial 18S rRNA is clearly prokaryotic in nature, showing significantly more sequence homology with 16S rRNAs than can be expected to arise by chance (p less than 0.000001); (2) shared oligonucleotide sequences include an especially high proportion of those identified as conserved in the evolution of prokaryotic rRNAs; and (3) wheat embryo mitochondrial and cytosol 18S rRNAs retain no more, and perhaps less, than the minimum sequence homology detectable by this sensitive method. These results argue in favor of an endosymbiotic origin for mitochondria.