Glutathione and the rate of cellular proliferation determine tumour cell sensitivity to tumour necrosis factor in vivo

Low rates of cellular proliferation are associated with low GSH content and enhanced sensitivity of Ehrlich ascites-tumour (EAT) cells to the cytotoxic effects of recombinant human tumour necrosis factor (rhTNF-alpha). Buthionine sulphoximine, a selective inhibitor of GSH synthesis, inhibited tumour growth and increased rhTNF-alpha cytoxicity in vitro. Administration of sublethal doses (10(6)units/kg per day) of rhTNF-alpha to EAT-bearing mice promoted oxidative stress (as measured by increases in intracellular peroxide levels, O2(-); generation and mitochondrial GSSG) and resulted in a slight reduction (19%) in tumour cell number when controls showed the highest rate of cellular proliferation. ATP (1mmol/kg per day)-induced selective GSH depletion, when combined with rhTNF-alpha administration, afforded a 61% inhibition of tumour growth and resulted in a significant extension of host survival. Administration of N-acetylcysteine (1mmol/kg per day) or GSH ester (5mmol/kg per day) abolished the rhTNF-alpha- and ATP-induced effects on tumour growth by maintaining high GSH levels in the cancer cells. Our results demonstrate that the sensitivity of tumour cells to rhTNF-alpha in vivo depends on their GSH content and their rate of proliferation.

Chronic stimulation differentially modulates expression of mRNA for dihydropyridine receptor isoforms in rat fast twitch skeletal muscle

This study examined the effects of low frequency chronic stimulation on expression of the mRNA encoding the two isoforms of the alpha1 subunit of the dihydropyridine receptor (DHPR) calcium channel, a critical component of skeletal muscle excitation-contraction coupling. RNase protection assay was used to determine alteration in isoform expression in 5-day, 9-day and 13-day chronically stimulated rat tibialis anterior muscle, and to compare it with soleus and extensor digitorum longus muscles. Low frequency chronic stimulation was associated not only with a significant decrease in the mRNA level of the skeletal isoform of the DHPR, but also with a significant increase in the mRNA level of the cardiac isoform of the DHPR, the overwhelming majority of which was the adult splice variant. Significant levels of cardiac DHPR mRNA expression were also found in normal adult slow twitch soleus muscle. These findings raise the question of a potential role for the cardiac DHPR in certain adult skeletal muscles.

[Auditory behavior monitoring after bacterial meningitis. Case report]

Bacterial meningitis is the main cause for acquired hearing loss. Nevertheless very little has been written about the development of the auditory behaviour either for improvement or for deterioration, after hospital release. The present study describes the case of a five month old boy with Haemophilus influenzae meningitis. Amongst various complications, a decrement in the auditory acuity was detected in the immediate evolution, with significant improvement later on by qualitative and quantitative tests.

Immunological and virological markers of disease progression in HIV-infected children

Polymerase chain reaction (PCR), virus culture and antigen detection assays are useful for early detection of vertically transmitted human immunodeficiency virus type 1 (HIV-1) infection in infants under 12 months of age. Sixty-four children born to HIV-1-seropositive mothers were evaluated. Thirteen children (20.3%) were repeatedly positive by PCR analysis. There was 100% concordance between the results obtained from PCR and culture assays. Measurement of p24 antigen in serum was, in contrast, a less sensitive marker of HIV infection: only 5/13 infants had positive p24 antigen results. We have investigated the relationship among the HIV-1 biological phenotype, replicative capacity of viral isolates, HIV RNA copy number in plasma, p24 antigenaemia, CD4 T lymphocyte counts and the clinical status in 13 HIV-infected infants. Six out of 13 HIV-1 isolates from these patients were classified as rapid/high and seven as slow/low. We have found a significantly positive correlation between the replication rate of HIV isolates and their capacity to induce syncytia in vitro. The HIV-1 isolates with rapid/high and syncytium-inducing phenotype, and isolates with slow/low and non-syncytium-inducing phenotype were obtained from infants who had HIV-1 RNA copy number ml(-1) plasma values of 27654-83520 and 1342-34321, respectively. Levels of HIV-1 RNA were measured in sequential plasma samples from three HIV-infected infants and their biological properties determined in vitro. Our findings indicate that infants who carried viruses with more cytophatic biological phenotype and who had higher viral RNA copy numbers in blood were more likely to have lower CD4+ T cell counts and more likely to develop full-blown AIDS.

[Esophageal pH-metry. Evaluation of prescriptions at the Robert-Debré Hospital (Paris)]

OBJECTIVES

To record orders for esophageal pH-metry at the Robert-Debré hospital in Paris and to assess the quality and pertinence on the order.

METHODS

A prospective survey of all children who underwent pH-metry during the month of February 1996 was conducted. There were 11 children included in the study.

RESULTS

Half of the pH-metries were performed in inpatients and half in outpatients including 18% scheduled directly by the exploration unit. The order did not provide any reason for the exploration in 15% of the cases (42% of those scheduled by the unit). When a reason was explained, the order described the clinical context in 86% of the cases but did not give any information on ongoing treatment in 40%. Clinical indications mentioned respiratory or ear-nose-throat disease in 70% of the cases and regurgitations or vomiting in 42%. Pathological reflux was diagnosed in one-third of the explorations. An anti-reflux treatment was prescribed for half of the patients. In reference to the official prescription guidelines in France (Référence Médicale Opposable, RMO), 72% of the orders were pertinent, 10% were questionable, 10% did not comply to official guidelines, and 8% could not be classified due to lack of information.

CONCLUSION

These findings point out that the official guidelines may be of questionable value in the hospital setting.

Earth-Based Radio Tracking of the Galileo Probe for Jupiter Wind Estimation

Although the Galileo probe was designed to communicate only to the orbiter, the probe radio signal was detected at two Earth-based radio observatories where the signal was a billion times weaker. The measured signal frequency was used to derive a vertical profile of the jovian zonal wind speed. Due to the mission geometry, the Earth-based wind estimates are less sensitive to descent trajectory errors than estimates based on probe-orbiter Doppler measurements. The two estimates of wind profiles agree qualitatively; both show high wind speeds at all depths sampled.

[Hypertrophic cardiomyopathy complicating a prolonged corticotherapy for hemorrhagic rectocolitis]

BACKGROUND

The cardiac side-effects of corticosteroid therapy are very uncommon.

CASE REPORT

A girl with ulcerative colitis developed at the age of 8 years an acute digestive episode despite prednisolone and total parenteral nutrition. The patient was then given intravenous methylprednisolone (2 mg/kg/d). Polypnea appeared 25 days later while blood pressure remained normal. Echocardiography revealed a cardiac hypertrophy associated with a systolic anterior motion of the mitral valve. Cardiac symptoms and echography findings returned to normal after reduction of corticosteroid therapy and its administration via the oral route.

CONCLUSION

Hypertrophic cardiomyopathy has been described in preterms treated with dexamethasone for bronchopulmonary dysplasia. It is exceptional in older children under corticosteroid therapy and its mechanism remains unknown.

Ultrasonographic assessment of inflammatory bowel disease in children: comparison with ileocolonoscopy

OBJECTIVES

To determine the feasibility and value of transabdominal ultrasonography of the terminal ileum and colon of children with inflammatory bowel disease (IBD) and to compare the findings with those of ileocolonoscopy.

STUDY DESIGN

Thirty-eight patients ranging in age from 4 to 18 years who underwent ileocolonoscopy for management of IBD or for diagnosis were studied prospectively. Twenty-one patients had Crohn disease, nine had ulcerative colitis, and eight served as control subjects. Transabdominal ultrasonography was performed on the day before ileocolonoscopy. Ultrasonographic findings were compared with the results of ileocolonoscopy, used as the reference method.

RESULTS

Peristalsis was recorded in all segments of the control subjects; the thickness of the terminal ileum was always less than 2.5 mm, and that of the large bowel, 2 mm or less. In the two patient subgroups, the thickness range of affected ileal and colonic segments was similar, but values were significantly different from those of the control subjects (chi-square test, p <0.0001). The overall sensitivity of the method was 88%, and the specificity, 93%.

CONCLUSION

Transabdominal ultrasonography should prove to be a useful clinical and investigational technique, although further studies are needed to assess its value in the treatment of children with IBD.

Blood glutathione as an index of radiation-induced oxidative stress in mice and humans

The effect of x-rays on GSH and GSSG levels in blood was studied in mice and humans. An HPLC method that we recently developed was applied to accurately determine GSSG levels in blood. The glutathione redox status (GSH/GSSG) decreases after irradiation. This effect is mainly due to an increase in GSSG levels. Mice received single fraction radiotherapy, at total doses of 1.0 to 7.0 Gy. Changes in GSSG in mouse blood can be detected 10 min after irradiation and last for 6 h within a range of 2.0-7.0 Gy. The highest levels of GSSG (20.1 +/- 2.9 microM), a 4.7-fold increase as compared with controls) in mouse blood are found 2 h after radiation exposure (5 Gy). Breast and lung cancer patients received fractionated radiotherapy at total doses of 50.0 or 60.0 Gy, respectively. GSH/GSSG also decreases in humans in a dose-response fashion. Two reasons may explain the radiation-induced increase in blood GSSG: (a) the reaction of GSH with radiation-induced free radicals resulting in the formation of thyl radicals that react to produce GSSG; and (b) an increase of GSSG release from different organs (e.g., the liver) into the blood. Our results indicate that the glutathione redox ratio in blood can be used as an index of radiation-induced oxidative stress.

Hypomethylation of human sperm pronuclear chromosomes

Using the methylase SssI enzyme, we have analyzed the degree of in situ methylation of human sperm pronuclear chromosomes obtained by fertilizing hamster oocytes with human sperm. Untreated (control) sperm chromosome complements showed a higher degree of in situ methylation, compared to sperm complements previously treated with 5-azadeoxycytidine or lymphocyte chromosomes. This indicates that human sperm pronuclear chromosomes have a lower degree of genomic methylation compared to that of other somatic cells. The similarity in the degree of in situ methylation of the euchromatic and heterochromatic regions of chromosomes 1, 9, 15, and 16 and the Y chromosome in human sperm does not support the existence of a possible correlation between hypomethylation and heterochromatin decondensation.

Regulation of dihydropyridine receptor and ryanodine receptor gene expression in regenerating skeletal muscle

One of the the major properties of mature skeletal muscle is its ability to regenerate after injury. The purpose of the present study was to determine whether the expression of genes encoding the dihydropyridine receptor calcium channel (DHPR) and the ryanodine receptor (RyR), which play a critical role in excitation-contraction coupling, is regulated by skeletal muscle regeneration. The process of regeneration was induced by bupivacaine injection in surgically exposed rat extensor digitorum longus (EDL) muscle. After total RNA isolation from the injected and the contralateral control EDL muscles performed 3, 7, 15 and 30 days following injection, Northern blot and RNase protection assays were carried out with four cDNA probes specific for the skeletal and cardiac muscle isoforms of both the DHPR alpha1-subunit and the RyR. After 3 days, an initial precipitous decrease in the expression of the genes encoding the skeletal muscle isoforms of the DHPR and RyR was observed, followed by an increase. Moreover, regenerating skeletal muscle transiently expressed mRNA for the DHPR cardiac isoform, mainly at the beginning of regeneration. No expression of mRNA for the cardiac RyR was observed. Contraction experiments, performed using EDL muscle at the same times after bupivacaine injection, showed that twitch amplitude was markedly decreased in the absence of external calcium, but only during the early stages of regeneration. Similar findings in relation to expression of skeletal and cardiac muscle DHPR message were previously reported from experiments conducted during early developmental stages using fetal skeletal muscle and muscle cell cultures [Chaudhari N, Beam KG (1993) Dev Biol 155:507-515]. These results suggest that expression of the DHPR cardiac isoform in skeletal muscle could explain certain cardiac-like aspects of excitation-contraction coupling of regenerating skeletal muscle and developing skeletal muscle as well.

Is nasal polyposis in cystic fibrosis a direct manifestation of genetic mutation or a complication of chronic infection?

Cystic fibrosis (CF) is the most common autosomal recessive disease among Caucasians. It is characterized by abnormal transepithelial sodium and chloride transport. The clinical expressions of the disorder are highly variable including nasal polyposis. Some authors have found that CF children with nasal polyposis form a distinct subgroup of patients within the clinical heterogeneity of the disease with milder gastrointestinal and pulmonary symptoms. The aim of this prospective study was to verify whether the clinical manifestations in CF children with nasal polyposis are different from control CF patients, and to identify any correlation between a phenotype of nasal polyposis and a genotype. Sixty-six CF children, aged 1-25 years, consecutively underwent ENT examination including nasal endoscopy. Twenty-one had nasal polyposis. The remainder formed the control group. There was no statistical difference in the mode and age of presentation of the disease between the two groups. The clinical manifestations (Schwachman and Kulczycki score, colonization by Staphylococcus aureus and Pseudomonas aeruginosa) were comparable between the two groups. We found no statistical difference in the repartition of genotypes between the polyposis and the control groups. Nasal polyposis does not seem to be genetically dependent, but a larger sample of patients is needed to reach an accurate conclusion.

Elevated levels of circulating intercellular adhesion molecule 1 and tumor necrosis factor alpha in the serum of children vertically infected with HIV-1

OBJECTIVE

To evaluate serum levels of circulating intercellular adhesion molecule-1 (cICAM-1) and tumor necrosis factor-alpha (TNF-alpha) levels in HIV-1-infected children at different stages of infection in children treated or not treated with Zidovudine (ZDV).

DESIGN

Serum levels of cICAM-1 and TNF-alpha, determined by enzyme immunoassays, were evaluated in 52 HIV-1-infected children, aged between 1 month and 13 years; 35 children were not treated with ZDV and 17 were treated with ZDV.

RESULTS

cICAM-1 (596 +/- 41 ng/ml) and TNF-alpha (284 +/- 29 pg/ml) levels were significantly elevated in HIV-1-infected children compared with HIV-1-uninfected age-matched controls (cICAM = 295 +/- 17 ng/ml; TNF-alpha = 4.8 +/- 0.89 pg/ml). No significant differences in either parameter were observed between children at different stages of HIV-1 disease. By contrast, a marked statistically significant, reduction of cICAM and TNF-alpha levels was observed in HIV-infected children undergoing antiretroviral therapy.

CONCLUSIONS

Serum levels of cICAM-1 and TNF-alpha were significantly elevated in HIV-1-infected children regardless of their clinical stage. Moreover, antiretroviral treatment appeared to reduce the serum levels of cICAM-1 and TNF-alpha.