Induction of hypoxia in experimental murine tumors by the nitric oxide synthase inhibitor, NG-nitro-L-arginine.

The nitric oxide synthase inhibitor NG-nitro-L-arginine (NOARG) was examined for its ability to alter energy metabolism in three murine tumors using 31P magnetic resonance spectroscopy. NOARG (10 mg/kg, i.v.) increased the inorganic phosphate:total phosphate ratio (Pi:total) 2-3-fold in the KHT, RIF-1, and SCCVII/Ha intradermal back tumors from 30 min to 6 h after injection, but the 31P magnetic resonance spectrum from normal tissue on the mouse back was unchanged after this treatment. NOARG (10 mg/kg, i.v.) injected 30 min before X-rays increased tumor cell survival 3-5-fold in SCCVII/Ha and 50-200-fold in RIF-1, measured using an in vivo/in vitro clonogenic assay. These effects were equivalent to those obtained from clamped tumors, indicating full radiobiological hypoxia. In KHT, only a 2-fold increase in radioresistance was observed after NOARG, which was less than the response of clamped tumors. In RIF-1 tumors, NOARG induced full radiobiological hypoxia when given from 30 min to 6 h prior to X-rays, consistent with the time course for the increase in Pi:total, measured by 31P magnetic resonance spectroscopy. Pi:total after NOARG doses of 0.1-10 mg/kg, i.v., increased in a dose-dependent manner in this tumor. Increased RIF-1 tumor radioresistance was similarly dependent on NOARG dose. The combination of the bioreductive agent RB6145 (300 mg/kg, i.p.) 15 min prior to NOARG (10 mg/kg, i.v.) produced greater than 5 decades of KHT tumor cell killing at 24 h after treatment. This combination also increased Pi:total 4.5-fold over the control value at 24 h in the KHT tumor. Histological examination of tumors at this time indicated extensive necrosis.

Protection of the eye during carotid angiography.

An eye shield was developed for use in neurological examinations in projections in which it does not interfere with the information sought. Use of this shield in A.P., oblique, 30 deg Towne's and 12 deg carotid Towne's projections reduced the corneal dose to approximately 5% of the unshielded value. For lateral projections, doses were reduced to approximately 5-15%. Use of the shield resulted in corneal doses of the order of 0.5 mrad/mAs and 1.0 mrad/mAs for standard and magnified projections respectively, with the exception of the lateral projections for which the corresponding values were approximately 0.3 mrad/mAs and 0.7 mrad/mAs. Corneal dose for a typical carotid angiogram was estimated to be reduced from 6.2 rad to 0.33 rad by the use of the shield.

Image quality of abdominal computed tomography in the elderly.

The hard copy images of 96 randomly selected patients ranging in age from 45 to 84 years who underwent routine abdominal computed tomography (CT) have been assessed. There was little variation in image quality with age although the best images were found in the younger men. The worst images were obtained in the younger women. Advanced age is not, by itself, a contra-indication for good quality abdominal CT on a modern unit.

Direct evidence for cytotoxicity associated with expression of hepatitis delta virus antigen.

It has been postulated that hepatocyte injury resulting from infection with hepatitis D virus may be caused by a direct virus cytotoxicity in contrast to immune-mediated injury associated with hepatitis B virus. We have transfected HeLa and HepG2 continuous cell lines with a recombinant plasmid containing the hepatitis D antigen gene under the inducible control of the human metallothionein promoter. The addition of zinc to the cell culture medium then led to the expression of hepatitis D antigen associated with, in the short term, a significant reduction in the rate of RNA but not DNA synthesis and, in the longer term, cell death. The necrotic cells had pyknotic nuclei and shrunken eosinophilic cytoplasm; these necrotic cells resembled the apoptotic bodies seen in hepatitis D virus-related hepatitis. The level of hepatitis D antigen in individual cells that produced these changes was similar to the level of hepatitis D antigen in hepatocytes from a chimpanzee with acute hepatitis D virus infection. We conclude that the expression of hepatitis D antigen resulted in significant cytotoxic changes in these cells, providing strong support for the view that hepatitis D antigen may be specifically cytotoxic to infected hepatocytes in vivo.

An integrated (2)H and (13)C NMR study of gluconeogenesis and TCA cycle flux in humans.

Hepatic glucose synthesis from glycogen, glycerol, and the tricarboxylic acid (TCA) cycle was measured in five overnight-fasted subjects by (1)H, (2)H, and (13)C NMR analysis of blood glucose, urinary acetaminophen glucuronide, and urinary phenylacetylglutamine after administration of [1,6-(13)C(2)]glucose, (2)H(2)O, and [U-(13)C(3)]propionate. This combination of tracers allows three separate elements of hepatic glucose production (GP) to be probed simultaneously in a single study: 1) endogenous GP, 2) the contribution of glycogen, phosphoenolpyruvate (PEP), and glycerol to GP, and 3) flux through PEP carboxykinase, pyruvate recycling, and the TCA cycle. Isotope-dilution measurements of [1,6-(13)C(2)] glucose by (1)H and (13)C NMR indicated that GP in 16-h-fasted humans was 10.7 +/- 0.9 micromol.kg(-1).min(-1). (2)H NMR spectra of monoacetone glucose (derived from plasma glucose) provided the relative (2)H enrichment at glucose H-2, H-5, and H-6S, which, in turn, reflects the contribution of glycogen, PEP, and glycerol to total GP (5.5 +/- 0.7, 4.8 +/- 1.0, and 0.4 +/- 0.3 micromol.kg(-1).min(-1), respectively). Interestingly, (13)C NMR isotopomer analysis of phenylacetylglutamine and acetaminophen glucuronide reported different values for PEP carboxykinase flux (68.8 +/- 9.8 vs. 37.5 +/- 7.9 micromol.kg(-1).min(-1)), PEP recycling flux (59.1 +/- 9.8 vs. 27.8 +/- 6.8 micromol.kg(-1).min(-1)), and TCA cycle flux (10.9 +/- 1.4 vs. 5.4 +/- 1.4 micromol.kg(-1).min(-1)). These differences may reflect zonation of propionate metabolism in the liver.

Microbore liquid chromatography coupled to a flow fast atom bombardment probe for the on-line detection of the Tyr-Pro cleavage of a nonapeptide by recombinant HIV-1 protease.

The nonapeptide Val-Ser-Gln-Asn-Tyr-Pro-Ile-Val-Gln has been reported as a model substrate for an aspartyl protease produced by the human immunodeficiency virus (HIV-1). Cleavage of this peptide at the Tyr-Pro linkage to produce tetra- and pentapeptide fragments is the basis of high-performance liquid chromatographic assays to detect HIV-1 protease activity. Confirmation of the cleavage site has been proved by using microbore liquid chromatography coupled to a dynamic fast atom bombardment interface. Comparison with fortified control incubates indicates that an approximate stoichiometric amount of the tetrapeptide was formed from the nonapeptide, confirming that the cleavage of the substrate by HIV-1 protease is both specific and quantitative.

Nursing care of oncology patients receiving chemotherapy.

As part of a research effort directed at identifying specific nursing activities related to the subsequent health status of the patient, this study explored relationships between selected nursing activities and patient outcomes for the oncology patient who was receiving chemotherapy. The study was correlational in design and descriptive in nature. Included in the study were 57 subjects from oncology and/or medical units in public and private nonprofit general hospitals. Human subjects' clearance was obtained for the study in each participating hospital. Data were collected primarily by means of patient and nurse responses to self-administered questionnaires. In the initial phase of data analysis, zero-order correlations were obtained for each pair of nursing activity and patient outcome variables. In addition, to identify relative contributions of different nursing activities to the health status of patients, regression analyses were performed in selected situations. The content and the quality of the explanation of the treatment and care regime were observed to be correlated positively with the patient's self-esteem. The quality of the explanation was observed to be positively related to the patient's knowledge base. Involving the patient in his care plan and giving him control over the activities of the day were positively correlated with importance of having things explained to him.

Randomized trial of a depression management program in high utilizers of medical care.

BACKGROUND: High utilizers of nonpsychiatric health care services have disproportionally high rates of undiagnosed or undertreated depression. OBJECTIVE: To determine the impact of offering a systematic primary care-based depression treatment program to depressed "high utilizers" not in active treatment. DESIGN: Randomized clinical trial. SETTING: One hundred sixty-three primary care practices in 3 health maintenance organizations located in different geographic regions of the United States. PATIENTS: A group of 1465 health maintenance organization members were identified as depressed high utilizers using a 2-stage telephone screening process. Eligibility criteria were met by 410 patients and 407 agreed to enroll: 218 in the depression management program (DMP) practices and 189 in the usual care (UC) group. INTERVENTION: The DMP included patient education materials, physician education programs, telephone-based treatment coordination, and antidepressant pharmacotherapy initiated and managed by patients' primary care physicians. MAIN OUTCOME MEASURES: Depression severity was measured using the Hamilton Depression Rating Scale (Ham-D) and functional status using the Medical Outcomes Study 20-item short form (SF-20) subscales. Outpatient visit and hospitalization rates were measured using the health plan's encounter data. RESULTS: Based on an intent-to-treat analysis, at least 3 antidepressant prescriptions were filled in the first 6 months by 151 (69.3%) of 218 of DMP patients vs 35 (18.5%) of 189 in UC (P < .001). Improvements in Ham-D scores were significantly greater in the intervention group at 6 weeks (P = .04), 3 months (P = .02), 6 months (P < .001), and 12 months (P < .001). At 12 months, DMP intervention patients were more improved than UC patients on the mental health, social functioning, and general health perceptions scales of the SF-20 (P < .05 for all). CONCLUSION: In depressed high utilizers not already in active treatment, a systematic primary care-based treatment program can substantially increase adequate antidepressant treatment, decrease depression severity, and improve general health status compared with usual care.