[Surgery of substernal goiter]

OBJECTIVE

To study the surgical approaches and operative techniques for substernal goiter.

METHOD

A retrospective study of 27 cases with substernal thyroid nodules was made in our hospital.

RESULT

The operations on 27 patients with substernal nodules have been successfully carried out. Among them, 10 were goiters, 9 adenomas, 4 malignancy and 4 were thyroid cancer metastasizing to paratracheal or substernal nodes. Resection via cervical collar incision was adequate in 23 cases. Three thyroid cancers with paratracheal node metastasis were completely resected by sternotomy and only one thyroid cancer with paratracheal and substernal nodes metastasis was resected by combined thoracotomy and cervical collar incision.

CONCLUSION

Resection via cervical collar incision for all retrosternal thyroid nodules were advised. The preliminary experience with this procedure suggests that it has some advantages in the management of substernal goiter, including: 1. ease of operation compared to both sternotomy and thoracotomy; 2. relatively low morbidity; 3. safe and reliable.

Hydrolysis theory for cisplatin and its analogues based on density functional studies

Hydrolysis of cisplatin, the most widely used anticancer drug in the world, is believed to be the key activation step before the drug reaching its intracellular target DNA. To obtain an accurate hydrolysis theory for this important class of square-planar Pt(II) complexes, three typical reactions, i.e., the first and second hydrolyses of cisplatin and the hydrolysis of [Pt(dien)Cl](+) (dien = diethylenetriamine), were studied at the experimental temperature with the solvent effect using mPW1PW91/SDD from a comprehensive methodological study on the Hartree-Fock (HF) ab initio method, electron correlation methods, pure density functional theory (DFT) methods, and hybrid HF-DFT methods with several basis sets. The true five stationary states in the second-order nucleophilic substitution (S(N)2) pathway for the hydrolysis process, namely, reactant (R) --> intermediate 1 (I1) --> TS --> intermediate 2 (I2) --> product (P) were obtained and characterized theoretically for the first time. The most remarkable structural variations and the associated atomic charge variations in the hydrolysis process were found to occur in the equatorial plane of the five-coordinate trigonal-bipyramidal (TBP)-like structures of I1, TS, and I2. The reaction with the TS structure of smaller L-M-E angle and more lengthened M-L and M-E bonds was found to have a smaller Gibbs free energy change and accordingly the better hydrolysis yield. It is found that the sum of the three concentric angles in the TBP's equator is near 360 degrees in I1 and I2 and is almost 360 degrees in TS in each reaction. The associated energy profiles again demonstrated a typical S(N)2 reaction curve. The computed forward and backward reaction enthalpy (Delta H(++)) and reaction entropy (Delta S(++)) in the rate-determining step I1 --> TS --> I2 are in good agreement with the experiments. Natural bonding orbital population analysis shows that the charge-separating extent follows the same order of Delta G in studied reactions. Comparing with the computational results of gas-phase reactions, it can be concluded that the solvent effect should be considered to obtain an accurate hydrolysis picture. The most affected structural parameters after solvation are related to the equatorial plane of the TBP-like geometry. The results provide theoretical guidance on detailed understanding on the mechanism of the hydrolysis of cisplatin, which could be useful in the design of novel Pt-based anticancer agents.

Transcriptional regulation of the two sterol esterification genes in the yeast Saccharomyces cerevisiae

Saccharomyces cerevisiae transcribes two genes, ARE1 and ARE2, that contribute disproportionately to the esterification of sterols. Are2p is the major enzyme isoform in a wild-type cell growing aerobically. This likely results from a combination of differential transcription initiation and transcript stability. By using ARE1 and ARE2 promoter fusions to lacZ reporters, we demonstrated that transcriptional initiation from the ARE1 promoter is significantly reduced compared to that from the ARE2 promoter. Furthermore, the half-life of the ARE2 mRNA is approximately 12 times as long as that of the ARE1 transcript. We present evidence that the primary role of the minor sterol esterification isoform encoded by ARE1 is to esterify sterol intermediates, whereas the role of the ARE2 enzyme is to esterify ergosterol, the end product of the pathway. Accordingly, the ARE1 promoter is upregulated in strains that accumulate ergosterol precursors. Furthermore, ARE1 and ARE2 are oppositely regulated by heme. Under heme-deficient growth conditions, ARE1 was upregulated fivefold while ARE2 was down-regulated. ARE2 requires the HAP1 transcription factor for optimal expression, and both ARE genes are derepressed in a rox1 (repressor of oxygen) mutant genetic background. We further report that the ARE genes are not subject to end product inhibition; neither ARE1 nor ARE2 transcription is altered in an are mutant background, nor does overexpression of either ARE gene alter the response of the ARE-lacZ reporter constructs. Our observations are consistent with an important physiological role for Are1p during anaerobic growth when heme is limiting and sterol precursors may accumulate. Conversely, Are2p is optimally required during aerobiosis when ergosterol is plentiful.

Flow-injection electrogenerated chemiluminescence determination of isoniazid using luminol

Based on a new electrogenerated chemiluminescence (ECL) analytical idea, this paper explains a sensitive and selective flow-injection ECL method using luminol for the determination of isoniazid, based on the sensitizing effect of isoniazid for the weak ECL emission of electrochemically oxidized luminol. Under the optimum experimental conditions, the relative ECL intensity was linear with isoniazid concentration in the range of 4.0 x 10(-8) mol/L to 8.0 x 10(-6) mol/L and with a detecting limit of 2.8 x 10(-8) mol/L.

[Rapid detection of enterohemorrhagic Escherichia coli in food with multiplex PCR assay]

Rapid detection of enterohemorrhagic Escherichia coli (EHEC) in food was achieved by using multiplex PCR assay. The assay was designed to amplify the 1109, 302 and 228 bp regions of corresponding virulence genes eaeA, hlyAB, slt1 and/or slt2, by using specific primers for each one reaction. In 60 EHEC and other strains, the above three virulence gene sequences were co-amplified from DNA isolated from 12 EHEC O157:H7 strains, 1 O26:H11 strain and 1 O111:H8 strain; eaeA sequence was amplified from DNA isolated from 2 EAEC strains; slt1/2 sequence was amplified from DNA isolated from 1 VTEC strain. No specific amplification product was produced from other 43 non-EHEC strains. For the detection of EHEC in food, results could be obtained within 8 hrs, and the sensitivity of assay was less than or equal to 1.6 cfu/g(ml) of food. The method was applied to 126 food samples, and EHEC was detected in 3 samples.

Knockout mice heterozygous for Sod2 show alterations in cardiac mitochondrial function and apoptosis

Heart mitochondria from heterozygous (Sod2(-/+)) knockout mice have a 50% reduction in manganese superoxide dismutase (MnSOD) activity. The decrease in MnSOD activity was associated with increased mitochondrial oxidative damage as demonstrated by a decrease in the activities of iron sulfhydryl proteins sensitive to oxygen stress (aconitase and reduced nicotinamide adenine dinucleotide-oxidoreductase). Mitochondrial function was altered in the Sod2(-/+) mice, as shown by decreased respiration by complex I and an increase in the sensitivity of the permeability transition to induction by calcium and t-butylhydroperoxide. The increased induction of the permeability transition in heart mitochondria from Sod2(-/+.)mice was associated with increased release of cytochrome c and an increase in DNA fragmentation. Cardiomyocytes isolated from neonatal Sod2(-/+) and Sod2(-/-) mice were more sensitive to cell death than cardiomyocytes from Sod2(+/+) mice after t-butylhydroperoxide treatment, and this increased sensitivity was prevented by inhibiting the permeability transition with cyclosporin A. These experiments demonstrate that MnSOD may play an important role in the induction of the mitochondrial pathway of apoptosis in the heart, and this appears to occur primarily through the permeability transition.

Titanium(IV) targets phosphoesters on nucleotides: implications for the mechanism of action of the anticancer drug titanocene dichloride

Abstract Reactions between the anticancer drug titanocene dichloride (Cp2TiCl2) and various nucleotides and their constituents in aqueous solution or N,N-dimethylformamide (DMF) have been investigated by 1H and 31P NMR spectroscopy and in the solid state by IR spectroscopy. In aqueous solution over the pH* (pH meter reading in D2O) range 2.3-6.5, CMP forms one new species with Ti(IV) bound only to the phosphate group. In acidic media at pH*<4.6, three species containing titanocene bound to the phosphate group of dGMP, AMP, dTMP and UMP are formed rapidly. The bases also appear to influence titanocene binding. Only one of these Ti(IV)-bound species can be detected in the pH* range of 4.6-6.5 in each case. The order of reactivity towards Cp2TiCl2(aq) at pH* ca. 3 is GMP>TMP approximately AMP > CMP. At pH* > 7.0, hydrolysis of Cp2TiCl2 predominated and little reaction with the nucleotides was observed. Binding of deoxyribose 5'-phosphate and 4-nitrophenyl phosphate to Cp2TiCl2(aq) via their phosphate groups was detected by 31P NMR spectroscopy, but no reaction between Cp2TiCl2(aq) and deoxyguanosine, 9-ethylguanine or deoxy-D-ribose was observed in aqueous solution. The nucleoside phosphodiesters 3',5'-cyclic GMP and 2',3'-cyclic CMP did not react with Cp2TiCl2(aq) in aqueous solution; however, in the less polar solvent DMF, 3',5'-cyclic GMP coordination to [Cp2Ti]2+ via its phosphodiester group was readily observed. Binding of titanocene to the phosphodiester group of the dinucleotide GpC was also observed in DMF by 31P NMR. The nucleoside triphosphates ATP and GTP reacted more extensively with Cp2TiCl2(aq) than their monophosphates; complexes with bound phosphate groups were formed in acidic media and to a lesser extent at neutral pH. Cleavage of phosphate bonds in ATP (and GTP) by Cp2TiCl2(aq) to form inorganic phosphate, AMP (or GMP) and ADP (or GDP) was observed in aqueous solutions. In addition, titanocene binding to ATP was not inhibited by Mg(II), but the ternary complex titanocene-ATP-Mg appeared to form. These reactions contrast markedly with those of the drug cisplatin, which binds predominantly to the base nitrogen atoms of nucleotides and only weakly to the phosphate groups. The high affinity of Ti(IV) for phosphate groups may be important for its biological activity.

Biological features of mesenchymal stem cells from human bone marrow

OBJECTIVE

To study the biological characteristics of mesenchymal stem cells (MSCs) from human bone marrow.

METHODS

A culture of mesenchymal stem cells was initiated from bone marrow low-density mononuclear cells separated by Percoll Centrifugation and maintained in low-glucose Dulbecco's modified Eagle's medium (DMEM) with 10% selected fetal calf serum. Cell growth pattern and its responses to cytokines were evaluated by trypan blue exclusion and MTT test, respectively. Cell cycle and surface antigenic features were analyzed by flow cytometry technique. Cytochemistry characteristics of MSCs were determined.

RESULTS

Easy-handling methods to isolate and culture expand MSCs were developed in this study. MSCs were unique in their phenotypes. They were positive for CD29, CD44, CD166, and negative for CD34, CD45, HLA-DR and Ulex europaeus. Cytochemistry evaluation showed that MSCs were homogeneously positive for acid alpha-naphthl acetate esterase (ANAE), glycogen (periodic acid Schiff reaction, PAS), and negative for acid phosphatase (ACP) and the Sudan black reaction (SB). Around 5% of them were positive for alkaline phosphatase (ALP). The cells had a population doubling time of 30 hours and cell cycle analysis showed that approximately 10% of them were in S phase. MSCs grew at significantly different rates when incubated in the presence of various recombinant human cytokines, of which interferon gamma, tumor necrosis factor alpha, stem cell factor and insulin-like growth factor promoted the proliferation of MSCs dramatically, while others tested had no effects on cell growth.

CONCLUSIONS

MSCs are a homogenous population of cells that have unique growth, phenotypical and cytochemical characteristics. Furthermore, the diverse responses of MSCs to different cytokines provide a clue for the selection of optimal expansion and maintenance of MSCs.

Triglyceride content in skeletal muscle: variability and the source

Intramyocellular triglycerides (imcTG) of skeletal muscle are an important energy source for muscle work in mammals. However, the metabolism and regulation of this small intracellular neutral lipid pool are largely unknown. This is in part due to the difficulties involved with its sampling and measurement introduced by contaminants of extramyocellular triglycerides (emcTG). The contents of imcTG reported to date for both human and rodent muscle are of unusually high variability not only across species, but also within same individuals and even same muscle groups. Recent studies suggested that the inherent muscle histologic heterogeneity does not appear to be a major source for the high variability as previously believed. Rather, the new experimental data showed that the procedures commonly used to process muscle specimens before lipid extraction appear inadequate to ensure a complete removal of emcTG contaminants. The extramyocellular lipid contaminants cause an overestimation of imcTG content and markedly increase its variability. Careful and meticulous microdissection has been found necessary in order to avoid contamination by emcTG, thereby obtaining pure muscle fibers for extraction of imcTG.

Chromatographic separation of proteins on metal immobilized iminodiacetic acid-bound molded monolithic rods of macroporous poly(glycidyl methacrylate-co-ethylene dimethacrylate)

Continuous rod of macroporous poly(glycidyl methacrylate-co-ethylene dimethacrylate) was prepared by a free radical polymerization within the confines of a stainless-steel column. The epoxide groups of the rod were modified by a reaction with iminodiacetic acid (IDA) that affords the active site to form metal IDA chelates used for immobilized metal affinity chromatography (IMAC). The efficiency of coupling of IDA to the epoxide-contained matrix was studied as a function of reaction time and temperature. High-performance separation of proteins, based on immobilized different metals on the column, were described. The influence of pH on the adsorption capacity of bovine serum albumin on the Cu2+-IDA continuous rod column was investigated in the range from 5.0 to 9.0. Purification of lysozyme from egg white and human serum albumin (HSA) on the commercially available HSA solution were performed on the naked IDA and Cu2+-IDA continuous rod columns, respectively; and the purity of the obtained fractions was detected by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry.

Identification of potential substrate-binding sites in yeast and human acyl-CoA sterol acyltransferases by mutagenesis of conserved sequences

In mammals, the esterification of sterols by ACAT plays a critical role in eukaryotic lipid homeostasis. Using the predominant isoform of the yeast ACAT-related enzyme family, Are2p, as a model, we targeted phylogenetically conserved sequences for mutagenesis in order to identify functionally important motifs. Deletion, truncation, and missense mutations implicate a regulatory role for the amino-terminal domain of Are2p and identified two carboxyl-terminal motifs as required for catalytic activity. A serine-to-leucine mutation in the (H/Y)SF motif (residues 338-340), unique to sterol esterification enzymes, nullified the activity and stability of yeast Are2p. Similarly, a tyrosine-to-alanine change in the FYxDWWN motif of Are2p (residues 523-529) produced an enzyme with decreased activity and apparent affinity for oleoyl-CoA. Mutagenesis of the tryptophan residues in this motif completely abolished activity. In human ACAT1, mutagenesis of the corresponding motifs (residues 268-270, and 403-409, respectively) also nullified enzymatic activity. On the basis of their critical roles in enzymatic activity and their sequence conservation, we propose that these motifs mediate sterol and acyl-CoA binding by this class of enzymes.

Study of tea polyphenol as a reversal agent for carcinoma cell lines' multidrug resistance (study of TP as a MDR reversal agent)

The aim of this study was to examine MDR1 expression product P-glycoprotein (Pgp) and study the effect and mechanism of tea polyphenol (TP) in reversion of multidrug resistance (MDR) in carcinoma cell lines. Immunocytochemical method was used for qualitative detection of Pgp. A comparative study of cytotoxicity and multidrug resistance reversion effect was made by MTT assay for tea polyphenol and quinidine in MCF-7 and MCF-7/Adr cell lines. The multidrug resistance reversion effect and mechanism were studied by measuring the uptake of 99mTc-tetrofosmin in the carcinoma cell lines. (1) The Pgp overexpression in MCF-7/Adr cells was found to be strong positive, while the Pgp expression of MCF-7 was negative. (2) Although both tea polyphenol and quinidine could not remarkably change the toxicity of adriamycin to MCF-7, they could improve the sensitivity of MCF-7/Adr to adriamycin. The reversion index of tea polyphenol and quinidine was 3 and 10 respectively. (3) The cellular uptake of 99mTc-tetrofosmin was remarkably lower in MCF-7/Adr than in MCF-7. The uptake of 99mTc-tetrofosmin in MCF-7/Adr exhibited a 4, 13, 16 fold increase in the presence of 200, 400 and 500 microg/ml of tea polyphenol respectively. The uptake of 99mTc-tetrofosmin in MCF-7/Adr exhibited only a 4-fold increase in the presence of 200 microM of quinidine. Immunocytochemistry can detect P-glycoprotein expression level qualitatively. Tea polyphenol is not only an anti-tumor agent, but also a multidrug resistant modulator similar to quinidine. The multidrug resistance reversion mechanism of tea polyphenol seems to be its inhibition of the activity of P-glycoprotein. Tea polyphenol has the advantage of very low toxicity in tumor treatment.

Targeted delivery of a peripheral benzodiazepine receptor ligand-gemcitabine conjugate to brain tumors in a xenograft model

PURPOSE

Peripheral benzodiazepine receptors (PBRs) are overexpressed in brain tumors compared to normal brain, and could serve as a target to selectively increase anticancer drug delivery through a PBR ligand-drug conjugate system. We have previously synthesized PBR ligand-gemcitabine conjugates based on the model PBR ligand, PK11195. The goal of the current study was to examine this new drug delivery strategy in an intracerebral xenograft model by measurement of steady-state drug distribution following administration of gemcitabine (GEM) and PK11195-GEM.

METHODS

In vitro PBR receptor binding and cytotoxicity assays were used to screen three different PK11195-GEM conjugates (GG01, GG02, GG03) in human SF126 glioma cells. Based on these findings and the favorable chemical stability of GG01, here referred as PK11195-GEM, pharmacokinetic investigations of PK11195-GEM and GEM were conducted in male rats. These studies consisted of single-dose and steady-state dosing regimen studies, the latter to assess drug distribution in normal brain and brain tumors. PK11195-GEM and GEM were measured in blood and tissue samples by HPLC.

RESULTS

All PBR-GEM conjugates demonstrated appreciable receptor binding affinity and cytotoxicity with mean IC50 values ranging from 248 to 376 nM and 5.6 to 29.1 nM, respectively. The cytotoxicity of GEM was comparable with a mean IC50 value of 5.9 nM. Following administration of single 8 mg/kg doses of PK11195-GEM to rats (n=4), PK11195-GEM had a mean total clearance of 126.3 +/- 29.6 ml/min per kg, and a volume of distribution at steady-state of 1,261.9 +/- 31.05 ml/kg that resulted in a very short elimination half-life of 16.1 +/- 5.8 min. In comparison GEM had a similar volume of distribution (993.8 +/- 131.6 ml/kg), reduced clearance (3.4 +/- 0.8 ml/ min per kg), and longer half-life (235.6 +/- 26.7 min). In nude rats bearing intracerebral tumors, mean steady-state tumor/plasma, tumor/right brain, and tumor/left brain PK 11195-GEM concentration ratios were 1.75 +/- 0.46, 5.49 +/- 5.2, and 9.96 +/- 3.2, respectively. The analogous values following GEM administrations were 0.81 0.5, 3.67 1.57, and 5.21 +/- 1.95, respectively. These values indicate a minimum twofold increase in tumor target selectivity for the conjugate delivery system compared to GEM treatment.

CONCLUSION

Targeting intracellular PBRs is a new drug delivery strategy based on the use of low molecular weight drug conjugates that can be administered systemically. It was demonstrated under steady-state conditions that PK11195-GEM possessed a twofold enhancement in brain tumor selectivity compared to GEM alone. This type of target selectivity would allow higher tumor concentrations to be achieved in conjunction with lower drug concentrations in normal or non-target tissues.

The anti-ageing action of dietary restriction

Over 60 years ago, McCay's laboratory showed that dietary or calorie-restriction dramatically increased the lifespan of rats. Since then, numerous laboratories with a variety of strains of rats and mice have confirmed this initial observation and have shown that reducing calorie intake (without malnutrition) significantly increases both the mean and maximum survival of rodents. Currently, dietary restriction is the only experimental manipulation that has been shown to retard ageing of mammals. Although mechanism whereby dietary restriction retards ageing is currently unknown, much of the emerging data suggest that the calorie-restricted rodents live longer and age more slowly because they are more resistant to stress and have an enhanced ability to protect cells against damaging agents.

[Eight cases of rhabdomyosarcoma in head and neck]

OBJECTIVE

To improve the clinical diagnosis and treatment level of rhabdomyosarcoma in head and neck.

METHOD

It was based on the documents that 8 cases of rhabdomyosarcoma in head and neck had been diagnosed by pathological diagnosis.

RESULT

The 8 cases were treated by operation. Among 8 patients, 5 took radiotherapy after operation. 1 took chemotherapy after operation. We kept in touch with 7 patients, the survival rate of 5 years was 57.1% (4/7).

CONCLUSION

We must pay attention to the painful or painless phyma in the otolaryngology and head and neck. It has the possibility of being rhabdomyosarcoma. We diagnose the rhabdomyosarcoma through biopsy and immuohistochemistry and with the references from the examination of CT, MR. In order to improve the survival rate of patients of rhabdomyosarcoma, we should use the comprehensive treatment, including operation, radiotherapy, and chemotherapy.

Radiologically guided percutaneous fine-needle aspiration biopsy of pelvic and retroperitoneal masses: a retrospective study of 68 cases

Fine-needle aspiration (FNA) of the pelvis and retroperitoneum (excluding the pancreas, kidney, and adrenal masses) has not achieved its full potential as a diagnostic modality. We reviewed 68 percutaneous, radiologically guided FNAs from these locations to assess the clinical utility and complication rate of this procedure. Satisfactory material was obtained in 66 cases (97.1%), of which 37 were deemed positive (55%), 3 suspicious (4%), 4 atypical (6%), and 22 negative (32%) for malignancy; two cases (3%) were unsatisfactory. Compared to biopsy (36 patients) and clinical information, the sensitivity and specificity of FNA for malignancy were 90.2% and 100%, respectively, yielding a positive predictive value of 100% and a negative predictive value of 86.6%. The four false-negative cases (5.9%) were due to sampling error. One patient had a minor complication (hematoma) from the procedure. We conclude that FNA is the procedure of choice for detecting most malignancies in these two locations.

Discrete-ordinates solution of short-pulsed laser transport in two-dimensional turbid media

The discrete-ordinates method is formulated to solve transient radiative transfer with the incorporation of a transient term in the transfer equation in two-dimensional rectangular enclosures containing absorbing, emitting, and anisotropically scattering media subject to diffuse and/or collimated laser irradiation. The governing equations resulting from the discrete-ordinates discretization of the angular directions are further discretized in the spatial and the temporal domains by the finite-volume approach. The current formulation is suitable for solving transient laser transport in turbid media as well as for steady-state radiative transfer in many engineering problems. The method is applied to several example problems and compared with existing steady-state solutions and Monte Carlo transient solutions. Good agreement is found in all cases. Short-pulsed laser interaction and propagation in a turbid medium with high scattering albedo are studied. The imaging of an inhomogeneous zone inside a turbid medium is demonstrated.

The essential role of MEKK3 in TNF-induced NF-kappaB activation

Activation of IkappaB kinase (IKK) is the key step in stimulation of the transcription factor NF-kappaB, which regulates many genes in the inflammatory response pathway. The molecular mechanism that underlies IKK activation in response to tumor necrosis factor (TNF) is still unknown. Using mitogen-activated protein kinase kinase kinase 3 (MEKK3)-deficient fibroblast cells, we found that MEKK3 plays a critical role in TNF-induced NF-kappaB activation. We have shown that MEKK3 is required for IKK activation and functions downstream of receptor-interacting protein (RIP) and TNF receptor- associated factor 2. We have also shown that MEKK3 interacts with RIP and directly phosphorylates IKK. The kinase activity of MEKK3 is pivotal to its function and, therefore, MEKK3 links RIP and IKK in TNF-induced NF-kappaB activation.

Mosaic pattern of maternal and paternal keratinocyte clones in normal human epidermis revealed by analysis of X-chromosome inactivation

During early development of the female embryo, one X-chromosome is randomly inactivated in each cell. As a result of growth, migration, and differentiation, the adult female becomes a mosaic of cells with either the paternal or the maternal X-chromosome inactivated. It is not known what structure the X-chromosome inactivation pattern has in skin of normal individuals. We investigated normal skin from four healthy females, heterozygous for the HUMARA microsatellite on the X-chromosome. Following careful microdissection, DNA from adjacent epidermal samples consisting of approximately 35 basal keratinocytes was digested with the methylation-sensitive enzyme HpaII. The inactivated X-chromosome remained intact due to extensive methylation. The enzyme-digested DNA was amplified using polymerase chain reaction and fragments were analyzed for size. Through examination of adjacent samples and consecutive sections, we found normal human skin to be composed of a fine mosaic of tiles with either maternal or paternal X-chromosome inactivated. The sizes of these tiles were between 20 and 350 basal cells. The method described has the potential to resolve the clonal status in normal as well as pathologic conditions.

Allelic losses in OraTest-directed biopsies of patients with prior upper aerodigestive tract malignancy

Genetic alterations at critical chromosome loci have been shown to be predictors of the progression of oral premalignancy-to-invasive cancer. We obtained a unique group of oral biopsies, initially collected during a prospective study designed to test the ability of OraTest (toluidine blue), to identify recurrent oral neoplastic lesions in patients with definite therapy for head and neck or upper aerodigestive tract (UADT) cancer. A total of 46 cases, including 13 squamous cell carcinoma (SCC), 11 carcinoma-in situ or dysplasia, and 22 morphologically normal oral biopsies, were analyzed for loss of heterozygosity (LOH) at 9p21, 3p21, and 17p13(TP53) by microsatellite analysis. LOH at one or more tested markers in at least one biopsy was detected in 76% (35 of 46) cases. All of the SCC and carcinoma-in situ cases showed LOH, and, strikingly, more than one-half (69%, 13 of 22) of morphologically normal epithelia also harbored LOH in at least one tested marker. The most frequent LOH was found on chromosome 9p21 (69%, 31 of 45). LOH was observed at 3p21, 17p13(TP53), or in multiple chromosomal arms significantly more often in SCC than in normal epithelia. In the majority of cases, two oral biopsies, one from an OraTest-staining positive area and another from a negative area adjacent to the stain, were collected. Among 25 LOH positive cases with two biopsies, identical allelic losses were confirmed between stained and nonstained biopsies in 16 cases. In the remaining nine cases with discordant LOH patterns between two biopsies, eight cases showed LOH at more genetic loci in OraTest-stained areas. Our data confirm that clonal genetic alterations, especially 9p21 deletion, are often present in the oral epithelia of patients with previous UADT malignancy and, combined with previous studies, suggest that genetic analysis will help stratify patients at risk of developing a secondary oral cancer. In addition to detecting cancer, our study suggests that OraTest can detect clinically occult lesions in the progression pathway to oral cancer.

Relation between commuting, leisure time physical activity and serum lipids in a Chinese urban population

PRIMARY OBJECTIVE

To analyse the association between both commuting and leisure time physical activity and serum lipids in a Chinese population.

POPULATION

A total of 1786 males and 1922 females aged 20-49 years.

METHODS

A cross-sectional survey was carried out in 1989 in urban area of the city of Tianjin, China. Commuting and leisure time physical activity, total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol and triglycerides were determined.

RESULTS

Daily walking or cycling to and from work was inversely associated with serum total cholesterol, low-density lipoprotein cholesterol and triglyceride concentrations among men and positively associated with high-density lipoprotein cholesterol concentrations among women as compared to travelling to and from work by bus.

CONCLUSIONS

The present study showed a significant association between serum lipids and commuting physical activity, but no relation with leisure time sports.

Sampling the intramyocellular triglycerides from skeletal muscle

To determine the extent and microanatomical distribution of extramyocellular adipocytes associated with skeletal muscle, histological, biochemical, nuclear magnetic resonance proton spectroscopic and microcomputed tomography techniques were employed to analyze skeletal muscle samples from lean and obese Sprague-Dawley rats. Significant amounts of extramyocellular adipocytes were found on the exterior surface of rat gastrocnemius, soleus, and tibialis anterior muscles. The triglyceride content of these exterior adipocytes in these muscle groups was 2- to 3-fold greater than that of the respective intramyocellular triglyceride pool (P = 0.01). Thus, the exterior adipocytes associated with skeletal muscle samples are an abundant source of extramyocellular fat potentially contaminating the intramyocellular triglyceride pool if not carefully and completely removed. On the other hand, no adipocytes were found in the interfascicular space (between muscle bundles) or the intrafascicular space (between muscle fibers) in any of the three rat muscles. The feasibility of and procedures for removing extramyocellular fat by microdissection techniques to obtain pure muscle sample were also evaluated. Complete removal of the extramyocellular adipocytes from rat skeletal muscle, using microdissection with a stereo microscope, was found to be practical and effective. It is concluded that pure muscle samples free of contamination by extramyocellular fat can be obtained, but only if microdissection techniques are utilized.

Changes in expression of antioxidant enzymes affect cell-mediated LDL oxidation and oxidized LDL-induced apoptosis in mouse aortic cells

Transgenic mice overexpressing Cu/Zn superoxide dismutase (hSod1Tg(+/0)) or catalase (hCatTg(+/0)) and knockout mice underexpressing manganese superoxide dismutase (Sod2(+/)(-)) or glutathione peroxidase-1 (Gpx1(-/-)) were used to study the effect of antioxidant enzymes on cell-mediated low density lipoprotein (LDL) oxidation and oxidized LDL (oxLDL)-induced apoptosis. Incubation of LDL with mouse aortic segments or smooth muscle cells (SMCs) resulted in a significant increase in LDL oxidation. However, LDL oxidation was significantly reduced when LDL was incubated with aortic segments and SMCs obtained from hSod1Tg(+/0) and hCatTg(+/0) mice compared with those obtained from wild-type mice. In contrast, LDL oxidation was significantly increased when LDL was incubated with aortic segments and SMCs obtained from Sod2(+/)(-) and Gpx1(-/-) mice. CuSO(4)-oxidized LDL increased DNA fragmentation and caspase activities in the primary cultures of mouse aortic SMCs. However, oxLDL-induced DNA fragmentation and caspase activities were reduced 50% in SMCs obtained from hSod1Tg(+/0) and hCatTg(+/0) mice compared with wild-type control mice. In contrast, oxLDL-induced DNA fragmentation and caspase activities were significantly increased in SMCs obtained from Sod2(+/)(-) and Gpx1(-/-) mice. These findings suggest that overexpression of Cu/Zn superoxide dismutase or catalase reduces cell-mediated LDL oxidation and oxLDL-induced apoptosis, whereas underexpression of manganese superoxide dismutase or glutathione peroxidase-1 increases cell-mediated LDL oxidation and oxLDL-induced apoptosis.

Immunotherapy with nondepleting anti-CD4 monoclonal antibodies but not CD28 antagonists protects islet graft in spontaneously diabetic nod mice from autoimmune destruction and allogeneic and xenogeneic graft rejection

BACKGROUND

T-cell activation and the subsequent induction of effector functions require not only the recognition of antigen peptides bound to MHC molecules by T-cell receptor (TCR) for antigen but also a costimulatory signal provided by antigen presenting cells. CD4 T-cell activation and function require the CD4 molecule as a coreceptor of TCR. The CD28/B7 pathway is a major costimulatory signal for T-cell activation and differentiation.

METHODS

The effect of targeting CD4 by nondepleting anti-CD4 monoclonal antibodies (mAbs) versus blocking CD28/B7 by CTLA4Ig, anti-CD80 mAbs, and anti-CD86 mAbs on the prevention of recurrence of autoimmune diabetes after MHC-matched nonobese diabetes-resistant (NOR) islet transplantation in nonobese diabetic (NOD) mice were compared. Whether nondepleting anti-CD4 mAbs prolong allogeneic islet graft survival and xenogeneic pig islet graft survival in diabetic NOD mice were studied. Furthermore, the effect of nondepleting anti-CD4 mAbs combined with CTLA4Ig on allogeneic islet graft survival in NOD mice was investigated.

RESULTS

Recurrence of autoimmune diabetes can be prevented by nondepleting anti-CD4 mAbs. Blocking the CD28/B7 costimulatory pathway by CTLA4Ig or by anti-CD80 mAbs and anti-CD86 mAbs cannot prevent recurrence of autoimmune diabetes after islet transplantation. Short-term treatment with nondepleting anti-CD4 mAbs significantly prolongs allogeneic islet graft survival and xenogeneic pig islet graft survival in diabetic NOD mice. But nondepleting anti-CD4 mAbs combined with CTLA4Ig decreased allogeneic islet graft survival.

CONCLUSIONS

Nondepleting anti-CD4 mAbs but not CD28 antagonists protect islet grafts in diabetic NOD mice from autoimmune destruction and allogeneic and xenogeneic graft rejection. The efficacy of nondepleting anti-CD4 mAbs is compromised when it combines with CTLA4Ig.

A reliable assessment of 8-oxo-2-deoxyguanosine levels in nuclear and mitochondrial DNA using the sodium iodide method to isolate DNA

A major controversy in the area of DNA biochemistry concerns the actual in vivo levels of oxidative damage in DNA. We show here that 8-oxo-2-deoxyguanosine (oxo8dG) generation during DNA isolation is eliminated using the sodium iodide (NaI) isolation method and that the level of oxo8dG in nuclear DNA (nDNA) is almost one-hundredth of the level obtained using the classical phenol method. We found using NaI that the ratio of oxo8dG/10(5 )deoxyguanosine (dG) in nDNA isolated from mouse tissues ranged from 0.032 +/- 0.002 for liver to 0.015 +/- 0.003 for brain. We observed a significant increase (10-fold) in oxo8dG in nDNA isolated from liver tissue after 2 Gy of gamma-irradiation when NaI was used to isolate DNA. The turnover of oxo8dG in nDNA was rapid, e.g. disappearance of oxo8dG in the mouse liver in vivo after gamma-irradiation had a half-life of 11 min. The levels of oxo8dG in mitochondrial DNA isolated from liver, heart and brain were 6-, 16- and 23-fold higher than nDNA from these tissues. Thus, our results showed that the steady-state levels of oxo8dG in mouse tissues range from 180 to 360 lesions in the nuclear genome and from one to two lesions in 100 mitochondrial genomes.