Is it possible to perform immediate cardiac assist using untrained latissimus dorsi muscle in a work-rest regimen?

The authors investigated what contractile force (CF) could be obtained from unconditioned latissimus dorsi muscle immediately after mobilization and for the 2 week vascular period of recovery. Latissimus dorsi muscle mobilization was performed on seven adult (4 experimental and 3 control) sheep leaving only the pedicle and the peripheral muscle intact. Telectronics stimulators (Myostim 7220; Teletronics Pacing Systems, Inc, Englewood, CO) were implanted. Immediately after mobilization 11-35% of the initial CF was lost. A 30 min fatigue test was performed 1 hr after mobilization (20 g/kg preload, 10 V, 10 Hz, 15 BPM, 6 impulses per burst) using a 1 min work-1 min rest regimen. Two sheep lost 2-12% of initial CF; two increased CF by 14-24%. At the end of the fatigue test, CF consisted of 74-89% of immobilized CF. Electrical stimulation training of the muscle was then initiated with the following regimen in the experimental animals only: 15 BPM, single impulses, 5 V, 10 Hz. Every day the muscle was exercised using a work-rest regimen to mimic cardiac assist, starting with 20 min on day 2, and increasing by 2 min per day until a total of 50 min was reached on day 16. All animals were retested for CF using a 42 min fatigue test on days 6, 11, and 16. On day 6, there was no fatigue evident in the experimental group during the 42 min test. CF after testing was 59-81% (mean 67%) of initial data. In the control group (animals with no electrical stimulation training protocol), CF decreased by 11% (from 64 to 53%). On day 11, there was no fatigue evident in the experimental group; CF in all animals increased by 2-8%. On day 16, there was also no fatigue evident in the experimental group; CF increased by 0-9%. An additional 20 min of continuous contraction (15 BPM) fatigue testing was performed on the muscle without rest between the tests. No fatigue was evident at the end of testing. Light microscopic analysis of latissimus dorsi muscle biopsy specimens taken on the days of testing showed no evidence of necrotic damage. Our investigations suggest that it may be possible to start muscle transformation immediately after mobilization and use the untrained latissimus dorsi muscle for cardiac assist immediately after surgery for short periods.     

Preclinical antitumor efficacy of the polyamine analogue N1, N11-diethylnorspermine administered by multiple injection or continuous infusion

Certain N-alkylated analogues of the natural polyamine spermine have been found to disrupt polyamine pool homeostasis and inhibit tumor cell growth. The most effective of these analogues, N1, N11-diethylnorspermine (DENSPM), apparently depletes intracellular polyamine pools primarily by inducing the polyamine acetylating enzyme spermidine/spermine N1-acetyltransferase, which contributes to polyamine depletion via increased polyamine excretion and catabolism. In this report, the experimental therapeutic efficacy of DENSPM was further examined with the use of other human solid tumor xenografts, including A121 ovarian carcinoma, A549 lung adenocarcinoma, HT29 colon carcinoma, and SH-1 melanoma, and compared with previously obtained findings with MALME-3M and PANUT-3 human melanomas. In vitro studies indicated that the growth sensitivity of most tumor cell lines to DENSPM was similar, with characteristically flat dose-response curves and IC50s ranging between 0.1 and 1 micrometer the only exception was the HT29 colon carcinoma cell line, which had an IC50 of >100 micrometer. For in vivo studies, DENSPM was administered by i.p. injection to female nude athymic mice at 40 and/or 80 mg/kg 3 times a day (every 8 h) for 6 days or by continuous s.c. infusion with the use of Alzet pumps at 120, 240, or 360 mg/kg/day for 4 days. Treatment began after s.c. tumor xenografts had reached 100-200 mm3. The SH-1 melanoma, A549 lung adenocarcinoma, and A121 ovarian carcinoma xenografts responded well to the i.p. administration of analogue with obvious tumor regressions, long-term tumor growth suppressions, and a significant proportion (up to 40%) of apparent cures (i.e., lack of tumor regrowth). However, in similarity to in vitro findings, HT29 colon carcinoma xenografts responded poorly to DENSPM treatment. Massive induction of N1-acetyltransferase activity and extensive depletion of polyamine pools were consistent findings in most tumor types after in vivo or in vitro treatment with DENSPM. The rapidly growing human LOX melanoma xenograft, however, demonstrated poor induction of N1-acetyltransferase activity and the poorest response to DENSPM treatment. In nude athymic mice with MALME-3M melanoma xenografts, constant infusion delivery of DENSPM resulted in prolonged inhibition of tumor growth and long-term tumor regressions comparable to those produced by multiple i.p. injections. On the basis of the unique structure of DENSPM, novel target and mode of intervention, mild host toxicity, and activity against different human solid tumor xenografts, DENSPM is currently being developed as an antitumor agent in humans.     

Exon scrambling of MLL transcripts occur commonly and mimic partial genomic duplication of the gene

The aim of this study was to test the hypothesis that prolactin may up- and down-regulate prolactin receptor gene expression in the anterior pituitary gland and hypothalamus respectively. Experiments were carried out in bantams (Gallus domesticus). Comparisons were made of concentrations of PRLR mRNA in the anterior pituitary gland and basal and preoptic hypothalamus in adult males and females held on long days (low vs high plasma prolactin); in 3-week-old juvenile male and females on short days (high vs low plasma prolactin); in 8-week-old juvenile male and females on short days (both low plasma prolactin); in adult laying, incubating, and out-of-lay (high, very high, and low plasma prolactin, respectively); in adult cockerels exposed to long or short days (high vs low prolactin); and in adult hens exposed to long or short days (high vs low prolactin). There was a sex difference in anterior pituitary and basal hypothalamic PRLR mRNA, with lower values in both tissues in females than in males. Compared with laying and out-of-lay hens, anterior pituitary and basal hypothalamic PRLR mRNA concentrations in incubating hens were increased and decreased, respectively. In adult birds of either sex held on long or short days, there was no difference in pituitary PRLR mRNA, while basal hypothalamic PRLR mRNA was lower on short days. PRLR mRNA in the preoptic hypothalamus was not affected by sex, reproductive state, or photoperiod. It is concluded that there is no consistent relationship between plasma prolactin, in the physiological range, and the concentration of PRLR mRNA in the anterior pituitary gland, basal hypothalamus, and preoptic hypothalamus.     

Role of an inhibitory pyrimidine element and polypyrimidine tract binding protein in repression of a regulated alpha-tropomyosin exon

The lipogenic enzyme fatty acid synthase (FAS) is elevated in various human primary cancers and certain human cancer cell lines. FAS overexpression in human neoplasia has clinical relevance because of its association with tumor aggression and potential chemotherapeutic intervention. Here, we surveyed FAS in cell lines established from normal murine mammary epithelium (NMuMG) and from mammary tumors induced by either rodent polyoma (Py) virus or murine mammary tumor virus (MMTV). Western blotting revealed greater content of FAS in Py-transformed A1-1 and T1 than NMuMG or MMTV-transformed Mm5MT, RIIIMT and MMT060562. These data suggest that signaling events mediated by Py transformation may increase cellular amounts of FAS. Although FAS content was elevated to similar levels in A1-1 and T1, specific activities were significantly different as enzyme activity in T1 was 3-fold higher than A1-1. Likewise, FAS activity in NMuMG was about 0.5-fold higher than the MMTV-transformed lines, even though enzyme content was similar. Immunoprecipitation studies employing anti-phosphoamino acid antibodies followed by immunoblot analysis with anti-FAS antisera (and vice versa) were used to characterize the constitutive phosphorylation state of the enzyme. Phosphoserine and phosphothreonine residues were detected in the more active FAS from T1 and NMuMG, but not in the less active FAS from Mm5MT or A1-1. Discovery of phosphorylated FAS suggests that the enzyme may have more immediate control over lipogenesis than previously thought. High-dose (10-4 M) dexamethasone induced FAS content and activity in NMuMG and MMTV-transformed lines but not Py-transformed cells. Lower concentrations (10-8, 10-6 M) of dexamethasone also activated FAS but without concomitant elevation of its protein content, which was consistent with a phosphorylated form of FAS. Finally, cell lines were treated with the FAS inhibitor cerulenin: almost all breast cancer lines were growth inhibited at significantly lower amounts of drug than normal cell lineages, suggesting that FAS plays a greater role in viability of tumor cells than normal cells. Pretreatment with palmitate (a primary end-product of FAS) prior to cerulenin rescued A1-1 cells only slightly from growth inhibition, whereas pretreatment with oleate (a monounsaturated fatty acid synthesized from palmitate) synergized cerulenin's cytotoxic effects.     

A natural kinase-deficient variant of fibroblast growth factor receptor 1

A fibroblast growth factor receptor 1 variant missing 37 amino acids from the carboxy-terminal tyrosine kinase catalytic domain was discovered in human lung fibroblasts and several other human cell lines. The receptor variant binds specifically to acidic fibroblast growth factor but has no tyrosine kinase activity. It was found that cellular transfectants expressing the fibroblast growth factor receptor 1 variant are mitogenically inactive and ligand binding to the receptor causes neither receptor autophosphorylation nor phospholipase C-gamma transphosphorylation. The fibroblast growth factor receptor 1 variant therefore represents an inactive receptor for acidic fibroblast growth factor. Since both kinase and kinase-deficient receptor forms are expressed in cells, it is conceivable that the kinase-deficient receptor plays an important role in regulating cellular responses elicited by acidic fibroblast growth factor stimulation.     

Managing the uncertainties of low-level radioactive waste disposal

A special program developed by the authors, called Pombe, identifies protein coding regions in the Schizosaccharomyces pombe genome. Linear discriminant analysis was applied to predict 5'-terminal, internal, 3'-terminal exons (coding-exon) and introns. The accuracy of the prediction was tested by cross verifications. The sensitivity, specificity and correlation coefficient for the internal exon prediction were 98.5%, 99.9% and 98.3% respectively at the nucleotide level. Open reading frames were studied and used to predict intron-less genes: 99.0% of such genes were identified with correct stopping sites. The gene structure was determined by dynamic programming and the prediction achieved 97.0% correlation coefficient at the nucleotide level. The program is available at http:(/)/clio.cshl.org/genefinder.     

Assessment of the biodegradation potential of psychrotrophic microorganisms

These experiments were designed to establish an animal model of acute carbon monoxide (CO) poisoning in awake habituated rats. On the day before exposure, under a brief anesthesia, a Levine preparation (unilateral common carotid artery occlusion) was performed on group 1 (n = 8) and 2 (n = 28), but not on group 3 rats (n = 8). Group 1 rats were exposed to air as control. Groups 2 and 3 rats were exposed to 0.27% CO in air for 60 min [carboxyhemoglobin (HbCO) = 70%] followed by a 2-day recovery in air. The Levine preparation per se did not induce any detectable physiologic effects on group 1 rats. Identical cardiovascular and metabolic responses to CO occurred in groups 2 and 3. After the CO exposure, all group 3 rats lived for 2 days with normal neurologic index (NI). In group 2 (n = 25 post-CO), 84% of the rats showed increased NI and edema of the ipsilateral cerebral hemisphere, and 76% of the rats died 8.7 +/- 1.7 h after the CO exposure. NI correlated with the brain edema (rs = 0.748, P < 0.001) and inversely correlated with the survival time after the CO exposure (rs = -0.777, P < 0.001). We therefore may conclude that exposure of the Levine-prepared rats to 0.27% CO in air for 60 min will provide a valuable model for testing of different treatments for CO poisoning.     

Prevalence of Cyclospora species and other enteric pathogens among children less than 5 years of age in Nepal

Stools from 124 Nepalese children aged 6 to 60 months with diarrhea were examined for organisms of the coccidian genus Cyclospora and for other enteric pathogens. Enterotoxigenic Escherichia coli, Giardia Lamblia, Campylobacter species, Cyclospora species, and Cryptosporidium species were the most common pathogens identified. Cyclospora species were detected in none of 74 children < 18 months of age compared with 6 (12%) of 50 children > or = 18 months of age (P = 0.004).