In vivo growth of mouse leukemia L1210 cells with metabolic alterations in the subunits of ribonucleotide reductase

Mouse leukemia L1210 cells selected for resistance to drugs targeted specifically at each of the protein subunits of ribonucleotide reductase were studied for their ability to grow in vivo. The life-span of the mice injected with hydroxyurea-resistant L1210 cells, which have elevated levels of the mRNA and protein for the non-heme iron (NHI, R2) subunit of ribonucleotide reductase, was approximately twice that of the mice injected with equal numbers of the parental wild-type L1210 leukemia cells. The life-span of mice injected with the L1210 cells that had alterations in the effector-binding subunit (EB, R1) was considerably shorter than the mice injected with the parental wild-type L1210 cells. These results provide direct evidence that tumor cells with alterations in the properties of ribonucleotide reductase grow differently in vivo, with defined effects on the host mouse that cause either an increased survival time or a decreased survival time compared to the effects of wild-type L1210 leukemia cells on tumor-bearing mice.     

Stimulation of Ca(2+) influx through ATP receptors on rat brain synaptosomes: identification of functional P2X(7) receptor subtypes

1. ATP receptors of the P2X class have previously been identified on autonomic nerve endings and on a limited population of CNS neurons. 2. In the present study P2X receptors on mammalian cortical synaptosomes have been identified by a variety of functional and biochemical studies. In choline buffer ATP analogues caused concentration/time dependent Ca(2+) influx. Relative to the effects caused by ATP, benzoylbenzoyl ATP (BzATP) was about seven times more active than ATP while 2-me-S-ATP and ATPgammaS were much less active. alpha,beta-me- ATP and beta,gamma-me-ATP were virtually inactive. In sucrose buffer, relative to choline buffer, the activity of BzATP was more than doubled while activity in sodium buffer was reduced. Moreover, the P2X antagonists PPADS or Brilliant Blue G both significantly attenuated influx. These observations suggest the presence of P2X receptors on synaptosomes which subserve Ca(2+) influx. This activity profile of the ATP analogues and the response to blocking agents are characteristic of responses of P2X(7) receptors. 3. Influx was unaffected by the VSCC inhibitors omega-CTx-MVIIC and (-) 202 - 791, indicating that ATP induced Ca(2+) influx occurred primarily through P2X receptors. 4. P2X(7) receptor protein was identified by Western blotting and immunohistochemical staining. Purified preparations were devoid of significant concentrations of GFAP or the microglial marker OX-42 but contained greatly enriched amounts of syntaxin and SNAP 25. 5. The various pharmacological and biochemical studies were all consistent with the presence of functional P2X(7) receptors.     

9-nitrocamptothecin liposome aerosol: lack of subacute toxicity in dogs

9-Nitrocamptothecin (9-NC) dilauroylphosphatidylcholine (DLPC) liposome aerosol was evaluated for potential toxicity in an 8-wk, subacute toxicity study in dogs. Fourteen adult dogs were divided into 2 groups with 10 animals in the 9-NC-DLPC treatment group and 4 animals in the DLPC-only vehicle control group. 9-NC-DLPC was administered to the animals using an Aerotech II nebulizer flowing at 10 L/min. Full-face exposures for 60 min were conducted for 5 consecutive days a week for 8 wk. The estimated deposited aerosol dose was 24.7 microg/kg/day. Animals in the vehicle control group received aerosolized DLPC only. Body weight, food consumption, urinalysis, in-life observations, hematology, plasma chemistry, and necropsy and histopathology were monitored before and during the treatment period and in a subset of animals for 2 wk following the end of treatment. Animals were observed for signs of pharmacologic and/or toxicologic effects three times on days of dosing and once daily on nondosing days. 9-NC-DLPC liposomes administered as a small-particle aerosol were determined to be nontoxic to dogs when given for 5 days/wk, for a duration of 8 wk. DLPC-only liposome also had no toxic effects.     

Deregulated homeobox gene expression in cancer: cause or consequence?

Homeobox genes comprise a large and essential family of developmental regulators that are vital for all aspects of growth and differentiation. Although many studies have reported their deregulated expression in cancer, few studies have established direct functional roles for homeobox genes in carcinogenesis. Nonetheless, most cases of deregulated homeobox gene expression in cancer conform to a simple rule: those that are normally expressed in undifferentiated cells are upregulated in cancer, whereas those that are normally expressed in differentiated tissues are downregulated in cancer.     

Effect of lumbar 5 ventral root transection on pain behaviors: a novel rat model for neuropathic pain without axotomy of primary sensory neurons

A peripheral nerve injury often causes neuropathic pain but the underlying mechanisms remain obscure. Several established animal models of peripheral neuropathic pain have greatly advanced our understanding of the diverse mechanisms of neuropathic pain. A common feature of these models is primary sensory neuron injury and the commingle of intact axons with degenerating axons in the sciatic nerve. Here we investigated whether neuropathic pain could be induced without sensory neuron injury following exposure of their peripheral axons to the milieu of Wallerian degeneration. We developed a unilateral lumbar 5 ventral root transection (L5 VRT) model in adult rats, in which L5 ventral root fibers entering the sciatic nerve were sectioned in the spinal canal. This model differs from previous ones in that DRG neurons and their afferents are kept uninjured and intact afferents expose to products of degenerating efferent ventral root fibers in the sciatic nerve and the denervated muscles. We found that the L5 VRT produced rapid (24 h after transection), robust and prolonged (56 days) bilateral mechanical allodynia, to a similar extent to that in rats with L5 spinal nerve transection (L5 SNT), cold allodynia and short-term thermal hyperalgesia (14 days). Furthermore, L5 VRT led to significant inflammation as demonstrated by infiltration of ED-1-positive monocytes/macrophages in the DRG, sciatic nerve and muscle fibers. These findings demonstrated that L5 VRT produced behavioral signs of neuropathic pain with high mechanical sensitivity and thermal responsiveness, and suggested that neuropathic pain can be induced without damage to sensory neurons. We propose that neuropathic pain in this model may be mediated by primed intact sensory neurons, which run through the milieu of Wallerian degeneration and inflammation after nerve injury. The L5 VRT model manifests the complex regional pain syndrome in some human patients, and it may provide an additional dimension to dissect out the mechanisms underlying neuropathic pain.     

Serial interleukin 6 measurements in the early diagnosis of neonatal sepsis

The objective of the present study was to evaluate serial interleukin 6 (IL6) levels in the early diagnosis of neonatal sepsis. Subjects included 255 neonates from the Neonatal Unit of Johannesburg Hospital evaluated for suspected sepsis between February and May 1998. All infants had IL6, full blood count (FBC), C reactive protein (CRP) and blood cultures done at presentation. CRP and IL6 were repeated after 24 h. Infants were categorized into groups according to the likelihood of infection on the basis of clinical presentation, CRP, FBC and culture results, i.e., group 1 (no infection) to group 4 (definite infection). IL6 was compared between the groups by the U-test of Mann-Whitney; stepwise logistic regression was done to establish the best predictors of infection, sensitivity, specificity, positive and negative predictive values were determined. The initial IL6 level was significantly raised in those infants with possible infection [880.67 pg/ml (2966.04), p value 0.0104], probable infection [422.62pg/ml (4077.7), p value 0.0021] and definite infection [11164.39pg/ml (24139.77), p value 0.0000] as compared to those infants without infection [58.65 (182.4)]. The best predictors of infection were the combination of the initial IL6 value and CRP value after 24 h (goodness of fit 97.7 per cent). An initial IL6 value below 20 pg/ml gave a negative predictive value of 90.18 per cent. It is concluded that an IL6 value done at the time of presentation of signs and symptoms suggestive of infection is useful in the early diagnosis of neonatal sepsis. In particular, an initial IL6 value below 20 pg/ml may allow antibiotics to be withheld in a number of infants evaluated for sepsis. There is no benefit in serial determination of IL6 in the diagnosis of neonatal sepsis.     

Zinc Gluconate Lozenges for Treating the Common Cold in Children: A Randomized Controlled Trial

Context.— The common cold is one of the most frequently occurring illnesses and is responsible for substantial morbidity and economic loss. Biochemical evidence suggests that zinc may be an effective treatment, and zinc gluconate glycine (ZGG) lozenges have been shown to reduce the duration of cold symptoms in adults. Objective.— To determine the efficacy of ZGG treatment of colds in children and adolescents. Design.— A randomized, double-masked, placebo-controlled study. Setting.— Two suburban school districts in Cleveland, Ohio. Patients.— A total of 249 students in grades 1 through 12 were enrolled within the first 24 hours of experiencing at least 2 of 9 symptoms of the common cold. Intervention.— Zinc lozenges, 10 mg, orally dissolved, 5 times a day (in grades 1-6) or 6 times a day (in grades 7-12). Main Outcome Measures.— Time to resolution of cold symptoms based on subjective daily symptom scores for cough, headache, hoarseness, muscle ache, nasal congestion, nasal drainage, scratchy throat, sore throat, and sneezing. Results.— Time to resolution of all cold symptoms did not differ significantly between students receiving zinc (n=124) and those receiving placebo (n=125) (median, 9 days; 95% confidence interval [CI], 8-9 days; median, 9 days, 95% CI, 7-10 days, respectively; P=.71). There were no significant differences in the time to resolution of any of the 9 symptoms studied. Compared with controls, more students in the zinc group reported adverse effects (88.6% vs 79.8%; P=.06); bad taste (60.2% vs 37.9%; P=.001); nausea (29.3% vs 16.1%; P=.01); mouth, tongue, or throat discomfort (36.6% vs 24.2%; P=.03); and diarrhea (10.6% vs 4.0%; P=.05). Conclusions.— In this community-based, randomized controlled trial, ZGG lozenges were not effective in treating cold symptoms in children and adolescents. Further studies with virologic testing are needed to clarify what role, if any, zinc may play in treating cold symptoms.      

T-cell lymphomas mask slower developing B-lymphoid and myeloid tumours in transgenic mice with broad haemopoietic expression of MYC

Deregulation of MYC expression occurs in many haematological malignancies. Previous studies modelling MYC-induced lymphomagenesis in the mouse used transgenic vectors that directed MYC overexpression in a lineage-specific manner. Here, we describe a transgenic mouse strain in which constitutive MYC expression is driven broadly in haemopoiesis by a vector containing regulatory elements of the Vav gene. Healthy young VavP-MYC17 mice had multiple haemopoietic abnormalities, most notably increased size and numbers of B-lymphoid cells, monocytes and megakaryocytes. The mice rapidly developed tumours and, surprisingly, these were exclusively T-cell lymphomas, mostly of mature CD4(+) CD8(-) T cells, a tumour type that is seldom seen in mouse models. To examine tumour development in the absence of the susceptible T cells, we bred VavP-MYC17 mice lacking the Rag1 recombinase. They survived longer and succumbed to tumours of several different haemopoietic cell types: pre-T cells, pro-B cells, macrophages and unusual progenitor cells. Thus, although T-lineage cells have the shortest latent period to transformation, the VavP-MYC17 transgene drives malignant transformation of multiple cell types and VavP-MYC17 mice provide a new model for tumours of multiple haemopoietic lineages.