The Adipose Organ Is a Unitary Structure in Mice and Humans

Obesity is the fifth leading cause of death worldwide. In mice and humans with obesity, the adipose organ undergoes remarkable morpho-functional alterations. The comprehension of the adipose organ function and organization is of paramount importance to understand its pathology and formulate future therapeutic strategies. In the present study, we performed anatomical dissections, magnetic resonance imaging, computed axial tomography and histological and immunohistochemical assessments of humans and mouse adipose tissues. We demonstrate that most of the two types of adipose tissues (white, WAT and brown, BAT) form a large unitary structure fulfilling all the requirements necessary to be considered as a true organ in both species. A detailed analysis of the gross anatomy of mouse adipose organs in different pathophysiological conditions (normal, cold, pregnancy, obesity) shows that the organ consists of a unitary structure composed of different tissues: WAT, BAT, and glands (pregnancy). Data from autoptic dissection of 8 cadavers, 2 females and 6 males (Age: 37.5 ± 9.7, BMI: 23 ± 2.7 kg/m²) and from detailed digital dissection of 4 digitalized cadavers, 2 females and 2 males (Age: 39 ± 14.2 years, BMI: 22.8 ± 4.3 kg/m²) confirmed the mixed (WAT and BAT) composition and the unitary structure of the adipose organ also in humans. Considering the remarkable endocrine roles of WAT and BAT, the definition of the endocrine adipose organ would be even more appropriate in mice and humans.

Antineoplastic Effect of a Combined Mitotane Treatment/Ionizing Radiation in Adrenocortical Carcinoma: A Preclinical Study

Mitotane (MTT) is an adrenolytic drug used in adjuvant and advanced treatments of adrenocortical carcinoma (ACC). Ionizing radiation (IR) is also used in adrenal cancer treatment, even though its biological action remains unknown. To provide a reliable in vivo preclinical model of ACC, we used mouse xenografts bearing human ACC to test the effects of MTT and IR alone and in combination. We evaluated tumor growth inhibition by the RECIST criteria and analyzed the cell cycle by flow cytometry (FCM). In the xenograft ACC model treated with MTT/IR in combination, we observed a marked inhibition of tumor growth, with strong tumor regression (p < 0.0001) compared to MTT and IR given alone (p < 0.05). The MTT results confirm its antisteroidogenic activity (p < 0.05) in the xenograft ACC model, revealing its ability to render cancer cells more prone to radiotherapy treatment. In addition, to explain the biological effect of these treatments on the Mismatch Repair System (MMR), we interfered with the MSH2 gene expression in untreated and MTT/IR-treated H295R and SW13 cell lines. Moreover, we observed that upon treatment with MTT/IR to induce DNA damage, MSH2 gene inhibition in both the H295R and SW13 cell lines did not allow DNA damage repair, thus inducing cell death. In conclusion, MTT seems to have a radiosensitizing property and, when given in combination with IR, is able to promote neoplastic growth inhibition, leading to a significant reduction in tumor size due to cell death.

Chemo-immunotherapy induces tumor regression in a mouse model of spontaneous mammary carcinogenesis

Tumor-specific immune tolerance represents an obstacle for the development of effective anti-tumor immune responses through cancer vaccines. We here evaluated the efficacy of chemo-immunotherapy in breaking tumor-specific immune tolerance in an almost incurable mouse model of spontaneous carcinogenesis.

Transgenic HER-2/neu mice bearing large mammary tumors received the adoptive transfer of splenocytes and serum isolated from immune donors, with or without pre-conditioning with cyclophosphamide. Treatment efficacy was assessed by monitoring tumor growth by manual inspection and by magnetic resonance imaging. The same chemo-immunotherapy protocol was tested on tumor-free HER-2/neu mice, to evaluate the effects on tumor emergence.

Our data show that chemo-immunotherapy hampered carcinogenesis and caused the regression of large mammary tumor lesions in tumor-bearing HER-2/neu mice. The complete eradication of a significant number of tumor lesions occurred only in mice receiving cyclophosphamide shortly before immunotherapy, and was associated with increased serum anti HER-2/p185 antibodies and tumor leukocyte infiltration. The same protocol significantly delayed the appearance of mammary tumors when administered to tumor-free HER-2/neu mice, indicating that this chemo-immunotherapy approach acted through the elicitation of an effective anti-tumor immune response. Overall, our data support the immune-modulatory role of chemotherapy in overcoming cancer immune tolerance when administered at lymphodepleting non-myeloablative doses shortly before transfer of antigen-specific immune cells and immunoglobulins. These findings open new perspectives on combining immune-modulatory chemotherapy and immunotherapy to overcome immune tolerance in cancer patients.

Ultramicronized palmitoylethanolamide rescues learning and memory impairments in a triple transgenic mouse model of Alzheimer's disease by exerting anti-inflammatory and neuroprotective effects

In an aging society, Alzheimer's disease (AD) exerts an increasingly serious health and economic burden. Current treatments provide inadequate symptomatic relief as several distinct pathological processes are thought to underlie the decline of cognitive and neural function seen in AD. This suggests that the efficacy of treatment requires a multitargeted approach. In this context, palmitoylethanolamide (PEA) provides a novel potential adjunct therapy that can be incorporated into a multitargeted treatment strategy. We used young (6-month-old) and adult (12-month-old) 3×Tg-AD mice that received ultramicronized PEA (um-PEA) for 3 months via a subcutaneous delivery system. Mice were tested with a range of cognitive and noncognitive tasks, scanned with magnetic resonance imaging/magnetic resonance spectroscopy (MRI/MRS), and neurochemical release was assessed by microdialysis. Potential neuropathological mechanisms were assessed postmortem by western blot, reverse transcription-polymerase chain reaction (RT-PCR), and immunofluorescence. Our data demonstrate that um-PEA improves learning and memory, and ameliorates both the depressive and anhedonia-like phenotype of 3×Tg-AD mice. Moreover, it reduces Aβ formation, the phosphorylation of tau proteins, and promotes neuronal survival in the CA1 subregion of the hippocampus. Finally, um-PEA normalizes astrocytic function, rebalances glutamatergic transmission, and restrains neuroinflammation. The efficacy of um-PEA is particularly potent in younger mice, suggesting its potential as an early treatment. These data demonstrate that um-PEA is a novel and effective promising treatment for AD with the potential to be integrated into a multitargeted treatment strategy in combination with other drugs. Um-PEA is already registered for human use. This, in combination with our data, suggests the potential to rapidly proceed to clinical use.

Key Players in Choline Metabolic Reprograming in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC), defined as lack of estrogen and progesterone receptors in the absence of protein overexpression/gene amplification of human epidermal growth factor receptor 2, is still a clinical challenge despite progress in breast cancer care. ¹H magnetic resonance spectroscopy allows identification and non-invasive monitoring of TNBC metabolic aberrations and elucidation of some key mechanisms underlying tumor progression. Thus, it has the potential to improve in vivo diagnosis and follow-up and also to identify new targets for treatment. Several studies have shown an altered phosphatidylcholine (PtdCho) metabolism in TNBCs, both in patients and in experimental models. Upregulation of choline kinase-alpha, an enzyme of the Kennedy pathway that phosphorylates free choline (Cho) to phosphocholine (PCho), is a major contributor to the increased PCho content detected in TNBCs. Phospholipase-mediated PtdCho headgroup hydrolysis also contributes to the build-up of a PCho pool in TNBC cells. The oncogene-driven PtdCho cycle appears to be fine tuned in TNBC cells in at least three ways: by modulating the choline import, by regulating the activity or expression of specific metabolic enzymes, and by contributing to the rewiring of the entire metabolic network. Thus, only by thoroughly dissecting these mechanisms, it will be possible to effectively translate this basic knowledge into further development and implementation of Cho-based imaging techniques and novel classes of therapeutics.

Targeting CXCR4 by a selective peptide antagonist modulates tumor microenvironment and microglia reactivity in a human glioblastoma model

BACKGROUND

The CXCL12/CXCR4 pathway regulates tumor cell proliferation, metastasis, angiogenesis and the tumor-microenvironment cross-talk in several solid tumors, including glioblastoma (GBM), the most common and fatal brain cancer. In the present study, we evaluated the effects of peptide R, a new specific CXCR4 antagonist that we recently developed by a ligand-based approach, in an in vitro and in vivo model of GBM. The well-characterized CXCR4 antagonist Plerixafor was also included in the study.

METHODS

The effects of peptide R on CXCR4 expression, cell survival and migration were assessed on the human glioblastoma cell line U87MG exposed to CXCL12, by immunofluorescence and western blotting, MTT assay, flow cytometry and transwell chamber migration assay. Peptide R was then tested in vivo, by using U87MG intracranial xenografts in CD1 nude mice. Peptide R was administered for 23 days since cell implantation and tumor volume was assessed by magnetic resonance imaging (MRI) at 4.7 T. Glioma associated microglia/macrophage (GAMs) polarization (anti-tumor M1 versus pro-tumor M2 phenotypes) and expressions of vascular endothelial growth factor (VEGF) and CD31 were assessed by immunohistochemistry and immunofluorescence.

RESULTS

We found that peptide R impairs the metabolic activity and cell proliferation of human U87MG cells and stably reduces CXCR4 expression and cell migration in response to CXCL12 in vitro. In the orthotopic U87MG model, peptide R reduced tumor cellularity, promoted M1 features of GAMs and astrogliosis, and hindered intra-tumor vasculature.

CONCLUSIONS

Our findings suggest that targeting CXCR4 by peptide R might represent a novel therapeutic approach against GBM, and contribute to the rationale to further explore in more complex pre-clinical settings the therapeutic potential of peptide R, alone or in combination with standard therapies of GBM.

Diesel exhaust particle exposure in vitro impacts T lymphocyte phenotype and function

Background

Diesel exhaust particles (DEP) are major constituents of ambient air pollution and their adverse health effect is an area of intensive investigations. With respect to the immune system, DEP have attracted significant research attention as a factor that could influence allergic diseases interfering with cytokine production and chemokine expression. With this exception, scant data are available on the impact of DEP on lymphocyte homeostasis. Here, the effects of nanoparticles from Euro 4 (E4) and Euro 5 (E5) light duty diesel engines on the phenotype and function of T lymphocytes from healthy donors were evaluated.

Methods

T lymphocytes were isolated from peripheral blood obtained from healthy volunteers and subsequently stimulated with different concentration (from 0.15 to 60 μg/ml) and at different time points (from 24 h to 9 days) of either E4 or E5 particles. Immunological parameters, including apoptosis, autophagy, proliferation levels, mitochondrial function, expression of activation markers and cytokine production were evaluated by cellular and molecular analyses.

Results

DEP exposure caused a pronounced autophagic-lysosomal blockade, thus interfering with a key mechanism involved in the maintaining of T cell homeostasis. Moreover, DEP decreased mitochondrial membrane potential but, unexpectedly, this effect did not result in changes of the apoptosis and/or necrosis levels, as well as of intracellular content of adenosine triphosphate (ATP). Finally, a down-regulation of the expression of the alpha chain of the interleukin (IL)-2 receptor (i.e., the CD25 molecule) as well as an abnormal Th1 cytokine expression profile (i.e., a decrease of IL-2 and interferon (IFN)-γ production) were observed after DEP exposure. No differences between the two compounds were detected in all studied parameters.

Conclusions

Overall, our data identify functional and phenotypic T lymphocyte parameters as relevant targets for DEP cytotoxicity, whose impairment could be detrimental, at least in the long run, for human health, favouring the development or the progression of diseases such as autoimmunity and cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-014-0074-0) contains supplementary material, which is available to authorized users.

Targeting estrogen receptor-α reduces adrenocortical cancer (ACC) cell growth in vitro and in vivo: potential therapeutic role of selective estrogen receptor modulators (SERMs) for ACC treatment

CONTEXT

Adrenocortical carcinoma (ACC) is a rare tumor with a very poor prognosis and no effective treatment. ACC is characterized by an increased production of IGF-II and by estrogen receptor (ER)-α up-regulation.

OBJECTIVE

The objective of this study was to define the role played by ERα in 17β-estradiol (E2)- and IGF-II-dependent ACC growth and evaluate whether selective estrogen receptor modulators are effective in controlling ACC growth in vivo.

EXPERIMENTAL DESIGN

The human adrenocortical cell line H295R was used as an in vitro model and to generate xenograft tumors in athymic nude mice.

RESULTS

In H295R cells IGF-II controlled expression of steroidogenic factor-1 that, in turn, increased aromatase transcription and, consequently, estrogen production, inducing cell proliferation. ERα silencing significantly blocked E2- and IGF-II-dependent cell proliferation. This effect was dependent on the regulation of cyclin D1 expression by ERα, activated in response to both E2 and IGF-II. In fact, IGF-II induced ERα activation by phosphorylating serine 118 and 167. Furthermore, we demonstrated that ERα mediated E2-induced nongenomic signaling that stimulated IGF-I receptor (IGF1R), ERK1/2, and AKT phosphorylation, resulting in a ligand-independent activation of the IGF1R-induced pathway. In addition, E2 potentiated this pathway by up-regulating IGF1R expression as a consequence of increased cAMP-responsive element binding protein activation and binding to IGF1R promoter. The estrogen antagonist, hydroxytamoxifen, the active metabolite of tamoxifen, reduced IGF1R protein levels and both E2- and IGF-II-induced cell proliferation. Moreover, H295R xenograft growth was strongly reduced by tamoxifen.

CONCLUSION

These findings establish a critical role for ERα in E2- and IGF-II-dependent ACC proliferation and provide a rationale for targeting ERα to control the proliferation of ACC.

T2-Weighted MRI Signal Alterations in the Early-Clinical Phase of Transmissible Spongiform Encephalopathy in a Scrapie Rodent Model

Background and Purpose

Transmissible spongiform encephalopathy (TSE) diseases are fatal, progressive neurodegenerative disorders affecting both humans and animals. Clinical signs typically appear after years and even decades of silent disease progression. This study was aimed at investigating whether altered brain MRI patterns may precede clinical signs in a TSE rodent model.

Methods

In vivo T2-weighted (T2W) MRI examinations (4.7 T) were performed on Golden Syrian hamsters (GSH) intracerebrally, orally, or intraperitoneally (i.p.) infected with the 263K scrapie strain. Histopathological analyses were performed on i.p. infected GSH at the end of one-day or longitudinal MRI sessions.

Results

T2W-MRI hyperintensity was detected in the thalamic nuclei of GSH with clinical signs, irrespective of the infection route. Hyperintensity in the thalamus was also observed in pre-clinical animals, between 106 and 121 days post-infection (dpi), while normal T2W intensity was detected in four animals examined between 72 and 96 dpi. Pathological prion protein deposition (but no astrogliosis and only occasionally, weak spongiosis) was detected between 106 and 121 dpi.

Conclusions

The altered T2W-MRI pattern detected in the thalamus of asymptomatic i.p. infected GSH provides a useful basis for evaluating the effectiveness of possible therapeutic approaches at early stages of TSE disease.

Generation and characterization of a human single-chain fragment variable (scFv) antibody against cytosine deaminase from yeast

BACKGROUND

The ability of cytosine deaminase (CD) to convert the antifungal agent 5-fluorocytosine (5-FC) into one of the most potent and largely used anticancer compound such as 5-fluorouracil (5-FU) raised considerable interest in this enzyme to model gene or antibody - directed enzyme-prodrug therapy (GDEPT/ADEPT) aiming to improve the therapeutic ratio (benefit versus toxic side-effects) of cancer chemotherapy. The selection and characterization of a human monoclonal antibody in single chain fragment (scFv) format represents a powerful reagent to allow in in vitro and in vivo detection of CD expression in GDEPT/ADEPT studies.

RESULTS

An enzymatic active recombinant CD from yeast (yCD) was expressed in E. coli system and used as antigen for biopanning approach of the large semi-synthetic ETH-2 antibody phage library. Several scFvs were isolated and specificity towards yCD was confirmed by Western blot and ELISA. Further, biochemical and functional investigations demonstrated that the binding of specific scFv with yCD did not interfere with the activity of the enzyme in converting 5-FC into 5-FU.

CONCLUSION

The construction of libraries of recombinant antibody fragments that are displayed on the surface of filamentous phage, and the selection of phage antibodies against target antigens, have become an important biotechnological tool in generating new monoclonal antibodies for research and clinical applications. The scFvH5 generated by this method is the first human antibody which is able to detect yCD in routinary laboratory techniques without interfering with its enzymatic function.

Type-3 metabotropic glutamate receptors negatively modulate bone morphogenetic protein receptor signaling and support the tumourigenic potential of glioma-initiating cells

Targeted-therapies enhancing differentiation of glioma-initiating cells (GICs) are potential innovative approaches to the treatment of malignant gliomas. These cells support tumour growth and recurrence and are resistant to radiotherapy and chemotherapy. We have found that GICs express mGlu3 metabotropic glutamate receptors. Activation of these receptors sustained the undifferentiated state of GICs in culture by negatively modulating the action of bone morphogenetic proteins, which physiologically signal through the phosphorylation of the transcription factors, Smads. The cross-talk between mGlu3 receptors and BMP receptors was mediated by the activation of the mitogen-activated protein kinase pathway. Remarkably, pharmacological blockade of mGlu3 receptors stimulated the differentiation of cultured GICs into astrocytes, an effect that appeared to be long lasting, independent of the growth conditions, and irreversible. In in vivo experiments, a 3-month treatment with the brain-permeant mGlu receptor antagonist, LY341495 limited the growth of infiltrating brain tumours originating from GICs implanted into the brain parenchyma of nude mice. While clusters of tumour cells were consistently found in the brain of control mice, they were virtually absent in a large proportion of mice treated with LY341495. These findings pave the way to a new non-cytotoxic treatment of malignant gliomas based on the use of mGlu3 receptor antagonists.

Gemcitabine treatment of experimental C6 glioma: the effects on cell cycle and apoptotic rate

Gemcitabine (dFdCyd) is a deoxycytidine analogue showing a broad spectrum of cytotoxic activity; additionally, at non-cytotoxic concentrations, it is a potent radiosensitiser. Its in vitro and in vivo effects were studied on C6 rat glioma. In vitro, dFdCyd induced an increase in S-phase cells at the end of treatment, with a reduction in G1 and G2 cell cycle-phase cells and relevant effects on the apoptotic rate. The in vivo effects of dFdCyd were studied on rats bearing intracranial C6 glioma. The drug was administered at a dose of 120 mg/Kg every 3 days x 4 doses. A significant effect on tumour growth was detected by longitudinal MRI analyses. Furthermore, the drug induced an inhibitory effect on tumour growth, 72 h after a 300 mg/Kg single dose. Analyses performed on tumour specimens showed relevant G1-phase accumulation and about 45% apoptotic cells. The present results justify further studies to determine the potential efficacy of dFdCyd in the treatment of malignant gliomas.

Pharmacological blockade of group II metabotropic glutamate receptors reduces the growth of glioma cells in vivo

U87MG human glioma cells in cultures expressed metabotropic glutamate (mGlu) receptors mGlu2 and mGlu3. Addition of the mGlu2/3 receptor antagonist LY341495 to the cultures reduced cell growth, expression of cyclin D1/2, and activation of the MAP kinase and phosphatidylinositol-3-kinase pathways. This is in line with the evidence that activation of mGlu2/3 receptors sustains glioma cell proliferation. U87MG cells were either implanted under the skin (1x10(6) cells/0.5 ml) or infused into the caudate nucleus (0.5x10(6) cells/5 microl) of nude mice. Animals were treated for 28 days with mGlu receptor antagonists by means of subcutaneous osmotic minipumps. Treatments with LY341495 or (2S)-alpha-ethylglutamate (both infused at a rate of 1 mg/kg per day) reduced the size of tumors growing under the skin. Infusion of LY341495 (10 mg/kg per day) also reduced the growth of brain tumors, as assessed by magnetic resonance imaging analysis carried out every seven days. The effect of drug treatment was particularly evident during the exponential phase of tumor growth, that is, between the third and the fourth week following cell implantation. Immunohistochemical analysis showed that U87MG cells retained the expression of mGlu2/3 receptors when implanted into the brain of nude mice. These data suggest that mGlu2/3 receptor antagonists are of potential use in the experimental treatment of malignant gliomas.

Sub-neurotoxic neonatal anoxia induces subtle behavioural changes and specific abnormalities in brain group-I metabotropic glutamate receptors in rats

Anoxia in the first week of life can induce neuronal death in vulnerable brain regions usually associated with an impairment of cognitive function that can be detected later in life. We set-up a model of subneurotoxic anoxia based on repeated exposures to 100% nitrogen during the first 7 days of post-natal life. This mild post-natal exposure to anoxia specifically modified the behaviour of the male adult rats, which showed an attention deficit and an increase in anxiety, without any impairment in spatial learning and any detectable brain damage (magnetic resonance imaging and histological analysis). Post-anoxic rats showed a reduction in the expression of group-I metabotropic glutamate receptors (i.e. mGlu1 and mGlu5 receptors) in the hippocampus and cerebral cortex, whereas expression of the mGlu 2/3 receptors, the NR1 subunit of NMDA receptors, and the GluR1 subunit of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptors was unchanged. mGlu1 and mGlu5 receptor signalling was also impaired in postanoxic rats, as revealed by a reduced efficacy of the agonist (1S,3R)-1-Aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD) to stimulate polyphosphoinositide hydrolysis in hippocampal slices. We conclude that rats subjected to subneurotoxic doses of anoxia during the early post-natal life develop behavioural symptoms that are frequently encountered in the inattentive subtype of the attention deficit hyperactivity disorder, and that group-I mGlu receptors may be involved in the pathophysiology of these symptoms.

Inhibition of left ventricular remodelling preserves chamber systolic function in pressure-overloaded mice

Controversy exists whether the development of left-ventricular hypertrophy (LVH) is a mechanism able to prevent cardiac dysfunction under conditions of pressure overload. In the present study we re-assessed the long-term effects of attenuating LVH by using L- and D-propranolol, which are equally able to inhibit the development of LVH induced by aortic banding. The aortic arch was banded proximal to the left common carotid artery in 71 CD-1 mice that were then assigned randomly to receive L-propranolol, D-propranolol (both 80 mg/kg per day) or vehicle. Concurrently, sham-operated mice were given L-propranolol, D-propranolol or vehicle. LV dimension and performance were evaluated under isoflurane anaesthesia by cine-magnetic resonance imaging, echocardiography and cardiac catheterization up to 8 weeks after surgery. After 2 weeks of pressure overload, the vehicle-treated banded mice had enhanced LV weight, normal chamber size and increased relative wall thickness (concentric hypertrophy), whereas L-propranolol- or D-propranolol-banded mice showed a markedly blunted hypertrophic response, i.e. normal chamber size and normal relative wall thickness, as well as preserved systolic LV chamber function. After 4 weeks, the vehicle-treated banded mice showed LV enlargement with a reduced relative wall thickness (eccentric remodelling) and a clear-cut deterioration in LV systolic function. In contrast, L-propranolol- or D-propranolol-treated banded mice showed normal chamber size with a normal relative wall thickness and preserved systolic function. A distinct histological feature was that in banded mice, L-or D-propranolol attenuated the development of cardiomyocyte hypertrophy but not the attendant myocardial fibrosis. At the 8-week stage, LV dysfunction was present in propranolol-treated banded mice although it was much less severe than in vehicle-treated banded mice. It is concluded that (i) deterioration of LV systolic performance is delayed if LV hypertrophy is inhibited, (ii) banding-induced deterioration of LV systolic function is associated with LV eccentric remodelling and (iii) the antihypertrophic effect of propranolol is due to a selective action on cardiomyocytes rather than on collagen accumulation

Proton MRI of (13)C distribution by J and chemical shift editing

The sensitivity of (13)C NMR imaging can be considerably favored by detecting the (1)H nuclei bound to (13)C nuclei via scalar J-interaction (X-filter). However, the J-editing approaches have difficulty in discriminating between compounds with similar J-constant as, for example, different glucose metabolites. In such cases, it is almost impossible to get J-edited images of a single-compound distribution, since the various molecules are distinguishable only via their chemical shift. In a recent application of J-editing to high-resolution spectroscopy, it has been shown that a more efficient chemical selectivity could be obtained by utilizing the larger chemical shift range of (13)C. This has been made by introducing frequency-selective (13)C pulses that allow a great capability of indirect chemical separation. Here a double-resonance imaging approach is proposed, based on both J-editing and (13)C chemical shift editing, which achieves a powerful chemical selectivity and is able to produce full maps of specific chemical compounds. Results are presented on a multicompartments sample containing solutions of glucose and lactic and glutamic acid in water.

In vivo detection of 13C-enriched glucose metabolites in mouse brain by T-SEDOR imaging

Protons J-coupled to 13C were selectively detected in the mouse head by in vivo 1H NMR imaging based on Twin Spin Echo DOuble Resonance (T-SEDOR) excitation. This pulse sequence combines a good chemical specificity with high sensitivity, requires no solvent pre-saturation and is well adapted to the imaging modality. 1H T-SEDOR maps of the mouse head allowed detection of areas of preferential accumulation of 13C-enriched compounds, upon repeated injections of uniformly 13C-labelled glucose, which induced hyperglycemia. The results demonstrated the feasibility, both in time scale and metabolite concentration, of applying T-SEDOR MRI for in vivo mapping brain areas characterized by enhanced rates of glucose uptake and/or accumulation of its metabolites.

Double-resonance J-edited (1)H-NMR detection of 6-(13)C-D-2-deoxyglucose uptake in glioma cells

The C6 methylene protons were selectively detected in (1)H-NMR spectra of intact glioma cells incubated with 6-(13)C-D-2-deoxyglucose (6-(13)C-2dG), a (13)C-enriched glucose analog that is suitable for monitoring glucose utilization in brain tumors. Spectral editing via (1)H-(13)C scalar coupling was performed with twin spin-echo double resonance (T-SEDOR), a pulse sequence which combines chemical specificity and high sensitivity, requires no solvent pre-saturation, and can easily be adapted to imaging protocols. This work demonstrates the suitability of the pulse sequence for monitoring 6-(13)C-2dG uptake in living cells in vitro, in spite of line-broadening and the occurrence of other strong signals in the spectral region of interest (3.5-4.4 ppm).

Phosphocholine and phosphoethanolamine during chick embryo myogenesis: a (31)P-NMR study

Elevated contents of phosphoethanolamine (Etn-P) and/or phosphocholine (Cho-P), a common feature of most tumours with respect to normal counterparts, may also occur in non-cancerous proliferating tissues. The significance of these alterations in relation to cell proliferation, differentiation and maturation is scarcely understood. In this work, the Cho-P and Etn-P pools were measured by (31)P-NMR in extracts of chick embryo pectoral muscle at different days of development. The average concentration of these metabolites exhibited the highest values (respectively, 1.5 and 3.0 micromol/mg DNA) on days 9-11 and decreased at later stages of myogenesis. While, however, Cho-P maintained substantial levels (above 1.0 micromol/mg DNA) also during myotube formation (days 11-18) and stepwise decreased (to about 0.5 micromol/mg DNA) upon fibres' maturation, Etn-P gradually decreased between day 11 and hatching time (down to about 0.2 micromol/mg DNA). These results demonstrate that significant changes may occur in the steady-state pools of these metabolites during normal in vivo cellular development and differentiation, and are consistent with: (a) high rates of phospholipid biosynthesis reported in the literature for proliferating myoblasts; (b) sustained phosphatidylcholine synthesis maintained also during myoblast fusion; and (c) decreased requirement of phospholipid synthesis in the last phase of in ovo myofibre maturation.

Respiratory mucus transportability is impaired in foundry workers: a longitudinal study

Mucus transportability impairment can prolong the permanence of occupational inhalable noxae within ciliated airways. A reliable, non-invasive indicator of mucus transportability is the Normalized Frog Palate Transport Rate (NFPTR). The aim of this 3-year prospective study was to compare NFPTR between a group of 166 foundry workers (E) and a group of 133 power plant workers (NE). In the first and third years of the study, workers underwent: clinical examination, spirometry, NFPTR, chest radiography. In both plants, environmental concentrations of respiratory irritants were well below the limits set by the American Conference of Governmental Industrial Hygienists. Both groups were homogeneous for age and smoking habits. Mean NFPTR was significantly lower in E than in NE in the first and third years of the study, and in smokers in comparison with non-smokers, at the end of the follow-up. NFPTR impairment was significantly associated with occupational exposure in the first and third years of the study. In the third year, a decline in NFPTR was associated with exposure, smoking habits, FVC and FEV1/FVC.100. At the end of the study, the means of FVC, FEV1 and PEF were significantly lower in E. No cases of pneumoconiosis were observed. In this study, low doses of foundry respiratory irritants were associated with impairment of mucus transportability; the consequent slowing of mucociliary clearance increased internal doses of foundry airborne noxae.

Potential role of in vitro 1H magnetic resonance spectroscopy in the definition of malignancy grading of human neuroepithelial brain tumours

The increasing sensitivity of neuro-imaging in the diagnosis of brain expanding lesions is not directly related to biopathological specificity and new technological approaches are under study. In particular Magnetic Resonance Spectroscopy (MRS) allows evaluation of some biochemical pathways whose metabolic alterations may be correlated with the nature and malignancy grading of primary brain tumours. In the present study the author performed an in vitro high field 1H MRS (9.4 and 14.1 T) analysis of specimens obtained from stereotactic biopsy or microsurgical removal of primary brain tumours. Different samples derived from heterogeneous areas and/or infiltrated perilesional regions were examined. This study was principally focused on malignancy grading of gliomas and its correlation with the ratio (R) between the resonance band arising from choline containing compounds (between 3.14 and 3.35 ppm) and the total creatine signal (3.0 ppm). Analyses allowed significant discrimination between astrocytomas (R = 2.4 +/- 0.6) and glioblastoma (GBM) (R = 4.4 +/- 1.3) [p < 0.002]; however the results did not allow discrimination between differentiated and anaplastic astrocytomas. The GBM showed the largest spread of values corresponding to their higher level of tissue heterogeneity and de-differentiation. Studies on non astrocytic brain tumours indicated that even higher R values were exhibited by oligodendrogliomas, even in well differentiated forms (p < 0.02 with respect to GBM). Moreover, preliminary observations indicated that signals arising from other metabolites may also contribute to a differential diagnosis of different oncotypes. Among these glycine appears particularly relevant, since higher levels were measured for this amino acid in GBM with respect to both astrocytomas and oligodendrogliomas.

Differentiation of glioblastoma multiforme from astrocytomas by in vitro 1H MRS analysis of human brain tumors

In vitro high resolution 1H NMR spectroscopy allows non-invasive metabolic evaluation of specimens derived from surgically biopsied or resected brain tumors, with the aim of identifying potential markers of different malignancy grading, and improving diagnostic and therapeutic strategies. In the present study we evaluated 36 patients affected by different brain gliomas (7 well differentiated astrocytomas, 7 anaplastic astrocytomas, 16 glioblastomas, 6 oligodendrogliomas). These analyses allowed discrimination between well differentiated and anaplastic astrocytomas (AII + AA) and glioblastoma multiforme (GM) samples on the basis of the ratio between the integrated choline-containing resonance (b"Cho") and the creatine peaks (creatine (Cr) + Phosphocreatine (PCr)). While no definite difference was found between AII and AA, significantly higher values were observed for this ratio in GM. Other signals, derived from different metabolites, such as Glycine (Gly) and N-acetyl-aspartate (NAA), may also assume relevance in differential tumor diagnosis. In this study an increased [Gly]/[Cr + PCr] ratio was observed in GM with respect to AII and AA. The NAA levels observed in our tumor specimens may be explained on the basis of tumor cell infiltration into brain adjacent tissue. Interesting, but inconclusive, are the data concerning oligodendrogliomas, which, also in well differentiated forms, exhibit increased levels of b"Cho"/(Cr + PCr) ratio. The present study confirms the role of MRS in the biochemical characterization of neoplastic brain tissue and its potential contribution to a better selection of multidisciplinary treatment strategies.

[Mucociliary clearance and respiratory function in foundry workers]

The aim of the study was to establish whether changes occur in respiratory function, particularly mucociliary clearance, among second fusion smeltery workers. The research covered 93 male smelters employed in steel forming and casting and 116 male workers of an electric power station, considered as non-exposed. Physiological, pathological and occupational histories of all subjects under study were available. An ECCS respiratory symptoms questionnaire was administered to all subjects ad the two groups also underwent a general medical examination, a spirometry and a chest X-ray. During the medical examination sputum was collected from the subjects to measure mucus transport rate on frog palate, expressed as Normalised Frog Palate Transport Rate (NFPTR). For the environmental research, dust, fumes and gas samplings were taken either at a fixed station or by means of personal dosimeters. Environmental research revealed very low concentrations of respiratory irritants (total dust: 0.2-6.8 mg/m3; respirable dust: 0.1-4.9 mg/m3; total silica: < 2-15.5%; respirable silica: < 0.004-0.3 mg/m3; iron: 0.008-0.085 mg/m3; chromium and manganese: < 0.001 mg/m3; fumes and gases: well below the TLV. The two groups were homogeneous with regard to age and smoking habits. Exposed workers showed rales, dyspnoea and spontaneous phlegm more frequently than non-exposed workers. NFPTR alterations were checked in 49 out of 81 exposed and in 18 out of 81 non-exposed subjects (chi squared = 22.9; p < 0.001). Stratification of the results according to smoking habits further confirmed the strong association between occupational exposure and NFPTR alterations. Smelters showed significantly lower mean NFPTR values compared to non-exposed subjects; also, the mean value of NFPTR in the exposed was below 0.70, which is considered the lowest individual limit in normal subjects. The only variable which explains a large part of the variability of NFPTR is past work in a smeltery rather than in an electric power station. The spirometries showed that only the mean PEF values were significantly lower among the exposed. Stratified analysis of the results according to smoking habits in the two groups revealed a close association between smeltery work and reduction of PEF to under 80% of the ECCS 1983 theoretical values, independently of smoking habits. We also compared the mean PEF values, both as measured values and as percent values of the ECCS 1983 theoretical values, stratified for occupational exposure and smoking; the results again showed that differences between these mean values were mainly due to current or past work in the foundry.(ABSTRACT TRUNCATED AT 400 WORDS)

Detection of neutral active phosphatidylcholine-specific phospholipase C in Friend leukemia cells before and after erythroid differentiation

With respect to normal tissues, 31P NMR spectra of tumors usually exhibit elevated phosphomonoester (PME) and phosphodiester (PDE) signals, arising from phospholipid metabolites such as phosphocholine (PCho) and glycerophosphocholine (GroPCho) (and/or ethanolamine analogues). PME and PDE resonances may undergo significant alterations during tumor growth, at early stages of tumor response to treatment or following cell differentiation and maturation. The enzymatic mechanisms which regulate these alterations are scarcely understood. Recent studies on agonist-induced phosphatidylcholine (PC) hydrolysis by PC-specific phospholipase C (PC-plc) in cells stimulated by hormones or growth factors suggest the hypothesis that repeated transient activations of this enzyme may also contribute to the elevation of PCho levels in tumor NMR spectra. This paper reports the first direct evidence on neutral active PC-plc activity in a tumour cell system, Friend leukemia cells, either in the undifferentiated (FLC) or differentiated state (dFLC). Cell homogenates were incubated in the presence of mixed diheptanoylphosphatidylcholine/sphingomyelin unilamellar vesicles (SLUV), which were previously shown to represent a good substrate for bacterial plc. 31P NMR analyses allowed the simultaneous detection and quantification of phosphorylated metabolites produced in tumor cell homogenates by PC-plc activity, as well by enzymes active in the PC deacylation pathway. With respect to FLC, dFLC homogenates exhibited higher PC-plc activity and lower accumulation of a deacylation product, GroPCho, in agreement with the elevation in the [PCho]/[GroPCho] ratio, already reported in 31P NMR spectra of intact differentiated cells. The direct detection of PC-plc in this cell system opens novel biochemical interpretations on a series of oncological observations, such as a) transient increases in the levels of PCho and PC-derived diacylglycerols reported in immature or in transformed cells in response to agonist-receptor interactions and b) accumulation of mobile lipids in tumor cell membranes and tissues.

In vivo 31P MRS of experimental tumours

More than 50% of cancers fail to respond to any individual treatment and tumour follow-up after treatment plays a major role in routine therapy planning and pharmacological research. Today, MRS is the only technological approach providing non-invasive access to tumour biochemistry. Ten years ago, expectations were raised concerning 31P MRS as an exciting and promising technical approach to the study of tumours. However the expectations have not always come to fruition. How close are we now to seeing routine 31P NMR in clinical oncology? This review of the 127 published papers shows spectroscopy results in more than 150 experimental animal tumour models. These tumour/host/treatment systems provide us with a useful basis to evaluate the current state of the art, summarize the basic knowledge presently available, determine the key points underlying the present disappointment of some clinical oncologists and stimulate new basic research. The information collected concerns the discussion of the reliability of experimental models in oncology, the technical improvement of magnetic resonance technology and the monitoring of bioenergetic status, pH regulation and phospholipid metabolism in treated and untreated tumours. Recent advances (two-thirds of the papers have been published in the last 5 years) seem to provide more optimistic perspectives than those generally accepted a few years ago, in the depressing period following early pioneering work.

Spin-lattice relaxation in murine tumors after in vivo treatment with interferon alpha/beta or tumor necrosis factor alpha

1H NMR spin-lattice relaxation times (T1) were measured in vitro and in vivo in Friend leukemia cell tumors during subcutaneous tumor growth in syngeneic mice and after in vivo administration of either purified murine interferon alpha/beta (IFN) or recombinant tumor necrosis factor alpha (TNF). Untreated tumors exhibited monoexponential T1 relaxation independently of tumor age at least until Day 16 after implantation. Histological examinations showed that under these conditions tumors were highly homogeneous and substantially free of necrotic areas. Peritumoral administrations of either IFN or TNF did not significantly alter the tumor relaxation properties at early stages of inhibition of tumor growth. The longitudinal relaxation decay became instead clearly biexponential at later stages (more than 7 days of IFN treatment or 2 days after TNF administration). While the T1 relaxation behavior could be unequivocally correlated with the presence of necrotic areas in these tumors, it could not be considered as an early marker of the altered growth capability, induced by administration of either IFN or TNF.

Alterations of lipid composition in Friend leukemia cell tumors in mice treated with tumor necrosis factor-alpha

Lipid analyses were carried out on transplantable murine Friend leukemia cell tumors, 6 h after intratumoral administration of tumor necrosis factor-alpha (TNF). The levels of the major phospholipid classes were uniformly decreased to about 70% of control values; free fatty acids were increased to about 170%; diacylglycerol was decreased to about 50% and triacylglycerol, the main lipid component, was not significantly altered. These results analysed in the light of concomitant alterations in the levels of phospholipid precursors and catabolites (determined in previous 31P NMR studies) and histological modifications demonstrated that at early stages of TNF-induced inhibition of tumor growth (a) phospholipid catabolism was significantly enhanced; (b) morphological changes were apparently correlated with alterations in the levels of phosphatidylcholine and its catabolic products.

Interleukin-1 beta induces tumor necrosis and early morphologic and metabolic changes in transplantable mouse tumors. Similarities with the anti-tumor effects of tumor necrosis factor alpha or beta

Peri-tumoral injection of recombinant human interleukin-1 beta in mice transplanted s.c. with Friend erythroleukemia cells (FLC) resulted in marked inhibition of tumor growth and increased survival. However, in vitro treatment of FLC (745 or 3Cl-8) with IL-1 beta barely inhibited cell multiplication. IL-1 beta, injected into established solid tumors, induced marked morphologic changes. Vascular congestion and focal extravasation of erythrocytes were observed as early as 6 hr after injection with IL-1 beta of FLC and L1210 tumors and HeJ16 fibrosarcomas. Focal areas of disaggregation of tumor cells and tumor necrosis were observed 6 and 24 hr after IL-1 injection. These morphologic changes were similar to those observed in FLC tumors or HeJ16 fibrosarcomas treated with TNF-alpha or beta. These cytokines determined morphological changes in tumor blood vessels of FLC tumors within 1 hr of injection. Freshly dissected FLC tumors and their tissue extracts were studied by Nuclear Magnetic Resonance (NMR) spectroscopy, shortly after peri-tumoral injection of IL-1 beta or TNF-beta. After 6 hr, both cytokines induced a 3-fold reduction in the levels of two catabolites, glycerophosphorylcholine and glycerophosphorylethanolamine, an accumulation of sn-glycerol 3-phosphate and a more than 10-fold increase in the choline/phosphorylcholine ratio. These results are similar to those reported for TNF-alpha, and can be interpreted on the basis of an activation of glycerophosphorylcholine phosphodiesterase (EC 3.1.4.2) and partial inhibition of choline kinase (EC 2.7.1.32). IL-1 beta and TNF-beta (like TNF-alpha) also induced alkaline shifts (0.10-0.25 units) in the average intratumoral pH value. We suggest that alterations of tumor blood vessels may be the primary events in solid tumors treated with IL-1 beta or TNF. Such alterations lead to early changes in tumor metabolism and subsequent tumor cell degeneration.

Tumor necrosis factor alpha induces early morphologic and metabolic alterations in Friend leukemia cell tumors and fibrosarcomas in mice

Morphologic and metabolic studies have been carried out on Friend leukemia cell (FLC) tumors (grown in DBA/2 mice) or fibrosarcomas (grown in C3H/HeN or C3H/HeJ mice) shortly after peritumoral injection of recombinant mouse tumor necrosis factor (TNF) alpha. Marked vascular congestion and focal extravasation of erythrocytes were observed as soon as 1 hr after injection of either FLC tumors or fibrosarcomas with TNF. Focal areas of disaggregation of tumor cells were observed 1 hr after injection of TNF. Intraluminal thrombi (composed of degranulated platelets and fibrin) were detected 3 and 6 hr after TNF treatment, and were associated with areas of depletion of endothelial cell cytoplasm. To correlate these morphologic changes in the tumor with alterations in tumor metabolism, NMR spectroscopy and biochemical studies were undertaken on freshly dissected FLC tumors and fibrosarcomas shortly after injection of TNF. The earliest metabolic alterations observed after 1 hr in TNF-treated FLC tumors of fibrosarcomas were: (i) increase in the average intratumoral pH; (ii) decrease in the levels of ATP. These phenomena were not associated with a reduced glycolytic capacity of TNF-treated tumors as, at these early times after injection, the levels of lactic acid were virtually the same for TNF-treated or control treated tumors. Alterations in the levels of some products of phospholipid degradation (GroPCho, GroPEtn, GroP and Cho) also occurred in these tumors as early as 3 hr after TNF treatment. These metabolic changes were not observed in ascitic FLC tumors after TNF treatment. We suggest that TNF induces alterations in tumor blood vessels which subsequently lead to changes in tumor metabolism and tumor degeneration.

Nuclear magnetic resonance analysis of tumor necrosis factor-induced alterations of phospholipid metabolites and pH in Friend leukemia cell tumors and fibrosarcomas in mice

The alterations induced on the pool sizes of five phospholipid metabolites, glycerol 3-phosphorycholine, glycerol 3-phosphorylethanolamine, phosphorylcholine, sn-glycerol 3-phosphate, and choline were studied by nuclear magnetic resonance (NMR) spectroscopy in murine tumors injected with recombinant murine tumor necrosis factor (TNF). Solid tumors were obtained by s.c. injection of either Friend leukemia cells (clones 3C1-8 and 745) in DBA/2 mice or murine fibrosarcoma cells (HeN4) in C3H/HeN mice. After tumor nodules had developed, TNF or bovine serum albumin was injected intratumorally. Treatment of both tumors with TNF resulted in a marked inhibition of tumor growth. 31P-NMR analyses of Friend leukemia cell tumors (and tissue extracts), 6 h after injection of TNF, showed: (a) a 1.5- to 3.5-fold decrease in the pool sizes of glycerol 3-phosphorylcholine and glycerol 3-phosphorylethanolamine; (b) a 7- to 8-fold increase of sn-glycerol 3-phosphate; (c) a 2- to 3.5-fold decrease of phosphorylcholine; (d) an alkaline shift (0.2 units) in intratumoral pH. Similar metabolic alterations occurred in TNF-treated HeN4 fibrosarcoma. 1H-NMR analyses of Friend leukemia cell tumor extracts also indicated, 6 h after tumor injection with TNF: (a) elevated choline levels (9X); (b) a 19-fold increase in the ratio [choline]/[phosporylcholine]; (c) elevated (1.4X) levels of lactic acid; and (d) a 1.6-fold decrease in the [taurine]/[glycine] ratio. The results are interpreted in the light of possible alterations in the activity of enzymes controlling the de novo biosynthesis and catabolism of phospholipids. We concluded that NMR spectroscopy can be a useful means to monitor the level of some phospholipid precursors and/or derivatives as early markers of therapeutic efficacy in intact neoplastic tissues.

Anti-tumor effects of interferon in mice injected with interferon-sensitive and interferon-resistant Friend leukemia cells. V. Comparisons with the action of tumor necrosis factor

A number of similarities and dissimilarities in the anti-tumor effects of TNF and interferon alpha/beta have been observed in DBA/2 mice injected with Friend erythroleukemia cells (FLC). Mouse TNF exerted marked anti-tumor effects in mice injected either s.c. or i.p. with FLC lines 3C18 or 3 gamma R8 resistant in vitro to the cytotoxic effects of TNF. Likewise, mouse interferon alpha/beta had anti-tumor activity in mice injected with these FLC, resistant to the action of interferon alpha/beta or gamma in vitro. The results of histopathologic examination and 31P nuclear magnetic resonance analyses of 3C18 FLC s.c. tumors injected with TNF resembled the results previously obtained for 3C18 FLC tumors injected with interferon alpha/beta, although the effects of TNF occurred more rapidly. Injection of mice with antibody to mouse interferon alpha/beta or gamma did not abrogate the anti-tumor effects of TNF in mice injected i.p. with FLC. Our results suggest that in this experimental system the anti-tumor effects of TNF, like interferon alpha/beta, do not result from a direct effect on the tumor cells themselves but are host-mediated.

31P-nuclear magnetic resonance analysis of interferon-induced alterations of phospholipid metabolites in interferon-sensitive and interferon-resistant Friend leukemia cell tumors in mice

Adult DBA/2 mice were given injections s.c. with either interferon-sensitive (745) or -resistant (3Cl-8) Friend erythroleukemia cells (FLC). After tumor nodules had developed, mouse interferon-alpha/beta was injected daily into the tumor. 31P-Nuclear magnetic resonance (NMR) spectroscopy examinations were undertaken on freshly dissected tumors at different days of treatment with either interferon or control preparations. Analysis of 745 FLC tumors in untreated mice at different days of tumor growth (day 8 to 13 after tumor implantation) showed marked increases in the levels of phosphorylcholine (PCho), glycerophosphorylethanolamine (GroPEtn) and glycerophosphorylcholine (GroPCho). In contrast high levels of PCho, GroPEtn and GroPCho were already detectable in the 3Cl-8 FLC tumors on day 8, and no significant changes were observed during subsequent tumor growth. The intracellular pH value remained practically constant in both FLC tumors. Daily intratumoral administration of either partially purified (10(7) IU/mg of protein) or highly purified (10(9) IU/mg of protein) mouse interferon-alpha/beta to both cell tumors resulted in decreases in the levels of PCho, GroPEtn and GroPCho and in increases in the intracellular pH with respect to tumors treated with control preparations or left untreated. Two days of daily treatment of mice with interferon sufficed to induce these metabolic changes which preceded the appearance of necrosis in the tumors. Treatment of FLC tumors with X-rays on day 12 of tumor growth did not result in any comparable metabolic changes 2 days after irradiation. Changes in the levels of phospholipid metabolites were not observed when 745 or 3Cl-8 cells were cultivated in the presence of interferon. As interferon induced these changes in both interferon-sensitive and -resistant tumors we conclude that interferon treatment results in host-mediated effects on the biosynthesis and/or catabolism of tumor cell phospholipids.

A 19F nuclear magnetic resonance study of uptake and metabolism of 5-fluorocytosine in susceptible and resistant strains of Candida albicans

The metabolism of the antifungal drug 5-fluorocytosine (5-FC) was studied in intact viable cells of Candida albicans by 19F nuclear magnetic resonance (NMR). The uptake of the drug and its conversion to the deaminated product 5-fluorouracil (5-FU) were easily observed by NMR analysis of both the cells and the supernatants of the incubation mixture. In the 5-FC-resistant mutant D14 of C. albicans, which lacked cytosine deaminase activity, the resonance peak of 5-FU was not observed. In intact cells of all 5-FC-susceptible strains the metabolism of 5-FU progressed to the formation of other fluorinated derivatives which were visualized as a single, broad resonance band at a lower field with respect to 5-FC and 5-FU. This band was resolved into three distinct peaks in the acid extract of treated cells, one of these peaks being attributable to 5-fluoro-dUMP (5-FdUMP). In strain 72R of C. albicans, which is 5-FC resistant because of a low level of UMP-pyrophosphorylase activity, the broad, low-field resonance band was detected later and with much less intensity than in the 5-FC-sensitive strains. This suggests that, besides 5-FdUMP, this band is also contributed to by 5-FUMP and possibly other phosphorylated derivatives. 19F NMR analysis also revealed that a significant amount of 5-FU is secreted into the external medium, the rate of secretion being higher in 5-FC-resistant strain 72R than in 5-FC-sensitive strain 72S. Although not all resonances were definitely identified, this study shows that 19F NMR spectroscopy may be an important tool for noninvasive analysis of the metabolism of fluorinated drugs in yeasts.

Modulations of glycerophosphorylcholine and phosphorylcholine in Friend erythroleukemia cells upon in vitro-induced erythroid differentiation: a 31P NMR study

A 31P NMR study has been carried out on Friend erythroleukemia cells (FLC) induced to undergo erythroid differentiation in vitro. Significant levels of glycerophosphorylcholine (GroPCho) and phosphorylcholine (P-Cho) were identified both in the untreated cells and in their PCA extracts. In FLC treated 4 days in vitro with either dimethylsulfoxide (DMSO) or hexamethylenebisacetamide (HMBA), the intracellular concentration of P-Cho was markedly increased, whereas that of GroPCho appeared to be significantly reduced. HMBA was more effective than DMSO in producing this effect. The concomitant modulations of GroPCho and P-Cho in differentiated FLC suggest the hypothesis that erythroid differentiation involves modifications of the regulatory mechanisms controlling biosynthesis and catabolism of phospholipids.

31P nuclear magnetic resonance study of growth and dimorphic transition in Candida albicans

A 31P NMR study of the fungal pathogen Candida albicans was carried out. Yeast-form cells at different phases of growth, as well as germ tubes and hyphae were examined. In all cases, the NMR spectra showed well separated resonance peaks arising from phosphorus-containing metabolites, the most prominent being attributable to inorganic phosphate (Pi) polyphosphates, sugar phosphates and mononucleotides, NAD, ADP and ATP. Relevant signals were also detected in the phosphodiester region. The intensity of most signals, as measured relative to that of Pi, was clearly modulated both at the different phases of growth and during yeast-to-mycelium conversion, suggesting significant changes in the intracellular concentration of the corresponding metabolites. In particular, the intensity of the polyphosphate signal was high in exponentially growing, yeast-form cells, then progressively declined in the stationary phase, was very low in germ tubes and, finally, undetectable in hyphae. NMR spectral analysis of the Pi region showed that from early-stationary phase, Pi was present in two different cellular compartments, probably corresponding to the cytoplasm and the vacuole. From the chemical shift of Pi, the pH values of these two compartments could be evaluated. The cytoplasmic pH was generally slightly lower than neutrality (6.7-6.8), whereas the vacuolar pH was always markedly more acidic.

Temperature dependence of intracellular pH in higher plant cells : A (31)P nuclear magnetic resonance study on maize root tips

The recent introduction of (31)P nuclear magnetic resonance spectroscopy offers a new approach to the problem of obtaining a simultaneous and direct evaluation of both the cytoplasmic and vacuolar pH in higher plant cells (J. K. M. Roberts, P.M. Ray, N. Waderlardetzky and O. Sardetzky, 1980, Nature 283, 870-872; 1981, Planta 152, 74-78). Using this method we have been able to detect a selective pH decrease of about 0.5 units at the level of the cytoplasmic compartment of maize root tips when the temperature was increased from 4 to 28°C. This effect was completely reversible with temperature. No pH variation could be detected at the level of the vacuolar compartment.