Oxygen consumption oscillates in single clonal pancreatic beta-cells (HIT)

Based on population studies, we have hypothesized that changes in metabolism in pancreatic beta-cells precede changes in Ca2+. It is well known from single-cell Ca2+ studies that variable oscillatory patterns in Ca2+ occur in response to glucose stimulation. The present studies, using the clonal beta-cell line HIT-T-15, were undertaken to evaluate the relationship between glucose concentration, insulin secretion, and O2 consumption and to determine the Ca2+ dependency of glucose-induced changes in O2 consumption. In population studies, an excellent correlation was found between respiration and insulin secretion, with half-maximal values at approximately 1 mmol/l glucose for both respiration and secretion. In the absence of Ca2+, glucose stimulated O2 consumption but not insulin secretion. In single clonal beta-cells, a self-referencing O2 electrode was used to assess O2 consumption. Large-amplitude oscillations were found to occur in response to stimulation by glucose and were blocked by uncoupling respiration with carbonylcyanide p-(trifluoromethoxy)phenylhydrazone (FCCP). They were also blocked and respiration totally inhibited by antimycin A, an inhibitor of complex III of the respiratory chain. Half of the cells sampled (approximately 100 total) exhibited increased oscillatory O2 consumption in response to glucose. Oscillations in O2 occurred in response to glucose even in the absence of Ca2+, and their amplitude increased further on restoration of a normal extracellular Ca2+ level. These studies indicated that oscillatory O2 consumption was not dependent on Ca2+ but that the amplitude of the O2 oscillations increased in the presence of Ca2+, possibly reflecting the additional work involved in insulin secretion and Ca2+ pumping. These studies demonstrated, for the first time, a direct correlation between O2 consumption and insulin secretion, the oscillatory nature of O2 consumption in single cells, and the feasibility of using a highly sensitive noninvasive on-line self-referencing O2 electrode to monitor single beta-cell respiration.

Calcification and measurements of net proton and oxygen flux reveal subcellular domains in Acetabularia acetabulum

Vegetative adults of Acetabularia acetabulum (L.) Silva were studied as a model system for subcellular patterning in plants, and a description of several phenotypic and physiological characteristics that reveal patterns of subcellular differentiation in this unicellular macroalga was undertaken. Initially, calcification patterns were studied. Under favorable conditions, the rhizoid and most of the stalk calcified. Only the apical 10-20% of the stalk and a small region adjacent to the rhizoid remained uncalcified. Calcification in algae has been reported to result from a biologically mediated local increase in alkalinity. To test this model extracellular pH and extracellular hydrogen ion gradients were examined with ion-selective, self-referencing, electrodes. In the light, A. acetabulum displayed a general pattern of extracellular alkalinity around the entire alga, although in some individuals the region near the rhizoid and the rhizoid itself displayed extracellular acidity. Acetabularia acetabulum also displayed net hydrogen ion influx at the rhizoid and the apical half of the stalk, variable flux in the lower part of the stalk, and net hydrogen ion efflux at the base of the stalk next to the rhizoid. The lack of complete correlation between external pH patterns and calcification suggests that other factors contribute to the control of calcification in this alga. To examine whether net hydrogen ion flux patterns correlated with photosynthetic or respiration patterns, oxygen flux was measured along the stalk using self-referencing O2 electrodes. Photosynthetic oxygen evolution occurred at comparable levels throughout the stalk, with less evolution in the rhizoid. Respiration mainly occurred near and in the rhizoid, with less O2 consumption occurring more apically along the stalk. Our studies of calcification patterns, net hydrogen ion flux and O2 flux revealed several overlapping patterns of subcellular differentiation in A. acetabulum.

Sustaining olfaction at low salinities: evidence for a paracellular route of ion movement from the hemolymph to the sensillar lymph in the olfactory sensilla of the blue crab Callinectes sapidus

Evidence reported previously suggests that in low-salinity conditions the integrity of the olfactory dendrites of the blue crab is sustained by a diffusion-generated ionic microenvironment within the aesthetascs. Diffusion of ions from the hemolymph to the sensillar lymph is proposed to maintain this microenvironment. In this study, using lanthanum as an electron-dense marker of extracellular fluid space, we find morphological evidence for paracellular continuity between the hemolymph and the sensillar lymph. Lanthanum penetrates extracellular fluid spaces within the aesthetascs when antennules are either perfused or bathed externally with solutions containing lanthanum nitrate. This was found in both freshwater- and seawater-acclimated animals. Evidence for ion diffusion from the aesthetascs was obtained using self-referencing, ion-selective microelectrodes. Both Ca2+ and K+ exhibit outwardly directed flux gradients associated with the aesthetasc tuft in low-salinity conditions. These findings are consistent with the concept that ion diffusion from the hemolymph to the sensillar lymph generates an ionic/osmotic microenvironment within the aesthetascs at low salinities.

The use of the photoplethysmograph to monitor the training of a cross-leg free flap prior to division

The cross-leg free flap is an important, although rarely used, option in the reconstruction of lower limb trauma. We report the use of photoplethysmography in the assessment of such a flap's training and the time of pedicle division.

Noninvasive measurement of potassium efflux as an early indicator of cell death in mouse embryos

Programmed cell death (apoptosis) occurs in nearly all cell types examined, including mammalian oocytes and embryos, where it may underlie some forms of infertility in humans. Although the molecular machinery participating in apoptosis have been intensely investigated, the accompanying physiological changes have not received similar attention. In this study, a novel electrophysiology technique has been employed to monitor real-time perturbations in the physiology of mouse embryos undergoing apoptosis evoked by hydrogen peroxide, diamide, and staurosporine. Despite differences in their mode of action, these agents evoked a similar early change in cellular physiology; namely, a pronounced, transient, potassium efflux through tetraethylammonium-sensitive potassium channels accompanied by cell shrinkage. Mouse zygotes exposed to 200 microM H(2)O(2) exhibited potassium efflux that elevated the potassium concentration of the media surrounding embryos by 1.4 +/- 0.1 microM. Pretreatment with tetraethylammonium inhibited this increase (0.2 +/- 0.1 microM). Our results indicate that potassium efflux through potassium channels and concurrent cell shrinkage are early indicators of cell death in embryos and that noninvasive measurements of potassium pathophysiology may identify embryos undergoing cell death prior to the manifestation of other morphological or molecular hallmarks of cell death.

STIM1: a novel phosphoprotein located at the cell surface

STIM1 is a novel candidate growth suppressor gene mapping to the human chromosome region 11p15.5 that is associated with several malignancies. STIM1 overexpression studies in G401 rhabdoid tumour, rhabdomyosarcoma and rodent myoblast cell lines causes growth arrest, consistent with a potential role as a tumour growth suppressor. We used highly specific antibodies to show by immunofluorescence and cell surface biotinylation studies that STIM1 is located at the cell surface of K562 cells. Western blot analysis revealed that the 90-kDa STIM1 protein is ubiquitously expressed in various human primary cells and tumour cell lines. STIM1 is not secreted from cells and does not appear to undergo proteolytic processing. We show evidence of post-translational modification of STIM1, namely phosphorylation and N-linked glycosylation. Phosphorylation of STIM1 in vivo occurs predominantly on serine residues. Thus, STIM1, the putative tumour growth suppressor gene is ubiquitously expressed and has features of a regulatory cell-surface phosphoprotein.

Characteristics of a novel deep red/infrared fluorescent cell-permeant DNA probe, DRAQ5, in intact human cells analyzed by flow cytometry, confocal and multiphoton microscopy

BACKGROUND

The multiparameter fluorometric analysis of intact and fixed cells often requires the use of a nuclear DNA discrimination signal with spectral separation from visible range fluorochromes. We have developed a novel deep red fluorescing bisalkylaminoanthraquinone, DRAQ5 (Ex(lambdamax) 646 nm; Em(lambdamax) 681 nm; Em(lambdarange) 665->800 nm), with high affinity for DNA and a high capacity to enter living cells. We describe here the spectral characteristics and applications of this synthetic compound, particularly in relation to cytometric analysis of the cell cycle.

METHODS

Cultured human tumor cells were examined for the ability to nuclear locate DRAQ5 using single and multiphoton laser scanning microscopy (LSM) and multiparameter flow cytometry.

RESULTS

Multiparameter flow cytometry shows that the dye can rapidly report the cellular DNA content of live and fixed cells at a resolution level adequate for cell cycle analysis and the cycle-specific expression of cellular proteins (e.g., cyclin B1). The preferential excitation of DRAQ5 by laser red lines (633/647 nm) was found to offer a means of fluorescence signal discrimination by selective excitation, with greatly reduced emission overlap with UV-excitable and visible range fluophors as compared with propidium iodide. LSM reveals nuclear architecture and clearly defines chromosomal elements in live cells. DRAQ5 was found to permit multiphoton imaging of nuclei using a 1,047-nm emitting mode-locked YLF laser. The unusual spectral properties of DRAQ5 also permit live cell DNA analysis using conventional 488 nm excitation and the single-photon imaging of nuclear fluorescence using laser excitation between 488 nm and low infrared (IR; 780 nm) wavelengths. Single and multiphoton microscopy studies revealed the ability of DRAQ5 to report three-dimensional nuclear structure and location in live cells expressing endoplasmic reticulum targeted-GFP, MitoTracker-stained mitochondria, or a vital cell probe for free zinc (Zinquin).

CONCLUSION

The fluorescence excitation and emission characteristics of DRAQ5 in living and fixed cells permit the incorporation of the measurement of cellular DNA content into a variety of multiparameter cytometric analyses.

Cadmium inhibits vacuolar H(+)ATPase-mediated acidification in the rat epididymis

In rats, an acidic luminal pH maintains sperm quiescence during storage in the epididymis. We recently showed that vacuolar H(+)ATPase-rich cells in the epididymis and vas deferens are involved in the acidification of these segments. Treatment of rats with cadmium (Cd) leads to alkalinization of this fluid by an unknown mechanism. Because Cd may affect H(+)ATPase function, we examined 1) the in vivo effect of Cd poisoning on H(+)ATPase-rich cell morphology and on the abundance and distribution of the 31-kDa H(+)ATPase subunit in cells along the rat epididymis, and 2) the in vitro effect of Cd on H(+)ATPase activity and function in the isolated vas deferens. Immunofluorescence and immunoblotting data from rats treated with Cd for 14-15 days (2 mg Cd/kg body mass/day) showed that 1) H(+)ATPase-positive cells regressed to a prepubertal phenotype, and 2) H(+)ATPase was lost from the apical pole of the cell and was redistributed into an intracellular compartment. In experiments in vitro, Cd inhibited bafilomycin-sensitive ATPase activity in isolated total cell membranes and, as measured using a proton-selective extracellular microelectrode, inhibited proton secretion in isolated vas deferens. We conclude that alkalinization of the tubule fluid in the epididymis and vas deferens of Cd-treated rats may result from the loss of functional H(+)ATPase enzyme in the cell apical domain as well as from a direct inhibition of H(+)ATPase function by Cd.

Oxidative phosphorylation-dependent and -independent oxygen consumption by individual preimplantation mouse embryos

The self-referencing electrode technique was employed to noninvasively measure gradients of dissolved oxygen in the medium immediately surrounding developing mouse embryos and, thereby, characterized changes in oxygen consumption and utilization during development. A gradient of depleted oxygen surrounded each embryo and could be detected >50 microm from the embryo. Blastocysts depleted the surrounding medium of 0.6+/-0.1 microM of oxygen, whereas early cleavage stage embryos depleted the medium of only 0.3+/-0.1 microM of oxygen, suggesting a twofold increase in oxygen consumption at the blastocyst stage. Mitochondrial oxidative phosphorylation (OXPHOS) accounted for 60-70% of the oxygen consumed by blastocysts, while it accounted for only 30% of the total oxygen consumed by cleavage-stage embryos. The amount of oxygen consumed by non-OXPHOS mechanisms remained relatively constant throughout preimplantation development. By contrast, the amount of oxygen consumed by OXPHOS in blastocysts is greater than that consumed by OXPHOS in cleavage-stage embryos. The amount of oxygen consumed by one-cell embryos was modulated by the absence of pyruvate from the culture medium. Treatment of one-cell embryos and blastocysts with diamide, an agent known to induce cell death in embryos, resulted in a decline in oxygen consumption, such that the medium surrounding dying embryos was not as depleted of oxygen as that surrounding untreated control embryos. Together these results validate the self-referencing electrode technique for analyzing oxygen consumption and utilization by preimplantation embryos and demonstrate that changes in oxygen consumption accompany important physiological events, such as development, response to medium metabolites, or cell death.

Programmable array microscopy with a ferroelectric liquid-crystal spatial light modulator

We present a programmable array microscope that uses a ferroelectric liquid-crystal spatial light modulator (SLM) for dynamic generation of scanning apertures. A single SLM serves as both the source and the detector aperture array in a double-pass confocal system. Successive aperture frames scan the array across the viewing area for complete imaging of a sample while preserving depth discrimination. Integration of the microscope output across all aperture frames produces a confocal image.

Tetanus toxin-mediated cleavage of cellubrevin inhibits proton secretion in the male reproductive tract

Our laboratory has previously shown that the vacuolar H(+)-ATPase, located in a subpopulation of specialized cells establishes a luminal acidic environment in the epididymis and proximal part of the vas deferens (Breton S, Smith PJS, Lui B, and Brown D. Nat Med 2: 470-472, 1996). Low luminal pH is critical for sperm maturation and maintenance of sperm in a quiescent state during storage in these organs. In the present study we examined the regulation of proton secretion in the epididymis and vas deferens. In vivo microtubule disruption by colchicine induced an almost complete loss of H(+)-ATPase apical polarity. Endocytotic vesicles, visualized by Texas red-dextran internalization, contain H(+)-ATPase, indicating active endocytosis of the pump. Cellubrevin, an analog of the vesicle soluble N-ethyl malemide-sensitive factor attachment protein (SNAP) receptor (v-SNARE) synaptobrevin, is highly enriched in H(+)-ATPase-rich cells of the epididymis and vas deferens, and tetanus toxin treatment markedly inhibited bafilomycin-sensitive proton secretion by 64.3+/-9.0% in the proximal vas deferens. Western blotting showed effective cleavage of cellubrevin by tetanus toxin in intact vas deferens, demonstrating that the toxin gained access to cellubrevin. These results suggest that H(+)-ATPase is actively endocytosed and exocytosed in proton-secreting cells of the epididymis and vas deferens and that net proton secretion requires the participation of the v-SNARE cellubrevin.

A novel deep red/low infrared fluorescent flow cytometric probe, DRAQ5NO, for the discrimination of intact nucleated cells in apoptotic cell populations

BACKGROUND

The linking of intracellular metabolism of anticancer drugs with cellular response is problematic. We describe a new probe for cellular integrity, based upon a structure which has the additional potential to act as a substrate for cytochrome P450-dependent bioreductive metabolism. DRAQ5NO is an N-oxide modified anthraquinone with optimal fluorescence excitation maxima compatible with He-Ne (633 nm) and Kr-Ar (647 nm) lasers.

METHODS

DRAQ5NO-loading and Annexin V binding was monitored using dual-laser flow cytometry (488 nm/633 nm wavelengths) in human lymphoma cultures undergoing anticancer drug- (etoposide; VP-16) induced apoptosis.

RESULTS

DRAQ5NO gave an Em(lambdamax) of 700.5 nm but retains DNA binding potential with an emission wavelength red-shift of approximately 12 nm. The agent showed reduced cytotoxicity and a limited capacity to accumulate within cells compared with the non-N-oxide form that shows a high nuclear targeting capacity in intact cells. DRAQ5NO/Annexin V provides for a positive discrimination between intact cells, membrane-compromised cells, cellular debris, and early stage apoptotic cells.

CONCLUSIONS

The spectral properties of DRAQ5NO allow for the use of visible range fluorochromes and differential excitation in multilaser systems for tracking apoptotic populations with implications for the measurement of bioreductive potential in complex tumour populations simultaneously undergoing physiologically or drug-induced apoptosis.

Bioactive alkaloids from Brunsvigia radulosa

A phytochemical investigation of the bulbs of Brunsvigia radulosa yielded the new alkaloid 1-O-acetylnorpluviine, together with the known structures 1-epideacetylbowdensine, crinamine, crinine, hamayne, lycorine, anhydrolycorin-6-one and sternbergine. All structures were established by spectroscopic evidence. Some of the 13C assignments which were reported for crinamine and hamayne were corrected by means of 2D NMR techniques. In order to provide a further structure for biological testing, crinamine was converted to apohaemanthamine. The alkaloids were tested for activity against two strains of cultured Plasmodium falciparum and for cytotoxicity with BL6 mouse melanoma cells.

Halicephalobus gingivalis (Nematoda) infection in a Grevy's zebra (Equus grevyi)

A 6-yr-old female Grevy's zebra (Equus grevyi) with a disseminated rhabditiform nematode infection is described. Antemortem clinical signs were limited to blindness and abnormal behavior believed to be caused by a recurrent nematode-induced uveitis. Histologic examination of the kidneys, heart, eyes, uterus, and lymph nodes revealed granulomas containing multiple sections of rhabditiform nematodes. Most of the recovered nematodes were larval stages with only a few adult females noted. The adults measured 243-297 microm x 11-16 microm (x = 269 x 14 microm). The distinctive rhabditiform esophagi had corpus:isthmus:bulb proportions of 19:11:5. On the basis of adult morphology, the nematode was identified as Halicephalobus gingivalis. This is the first report of this parasite in a zebra and indicates that this parasitic granulomatous disease should be considered in zebras with neurologic disease.

A non-invasive method for measuring preimplantation embryo physiology

The physiology of the early embryo may be indicative of embryo vitality and therefore methods for non-invasively monitoring physiological parameters from embryos could improve preimplantation diagnoses. The self-referencing electrophysiological technique is capable of non-invasive measurement of the physiology of individual cells by monitoring the movement of ions and molecules between the cell and the surrounding media. Here we use this technique to monitor gradients of calcium, potassium, oxygen and hydrogen peroxide around individual mouse preimplantation embryos. The calcium-sensitive electrode in self-referencing mode identified a region of elevated calcium concentration (approximately 0.25 pmol) surrounding each embryo. The calcium gradient surrounding embryos was relatively steep, such that the region of elevated calcium extended into the medium only 4 microns from the embryo. By contrast, using an oxygen-sensitive electrode an extensive gradient of reduced dissolved oxygen concentration was measured surrounding the embryo and extended tens of micrometres into the medium. A gradient of neither potassium nor hydrogen peroxide was observed around unperturbed embryos. We also demonstrate that monitoring the physiology of embryos using the self-referencing technique does not compromise their subsequent development. Blastocyts studied with the self-referencing technique implanted and developed to term at the same frequency as did unexamined, control embryos. Therefore, the self-referencing electrode provides a valuable non-invasive technique for studying the physiology and pathophysiology of individual embryos without hindering their subsequent development.

The effect of 5-fluorouracil on Dupuytren fibroblast proliferation and differentiation

INTRODUCTION

Dupuytren's disease is a proliferative disease with contractile properties, prone to recur after surgery. Intra-operatively applied 5-fluorouracil has been used to avoid scar problems in the eye after glaucoma filtration surgery and was therefore investigated as a means to inhibit proliferation and myofibroblast differentiation in Dupuytren fibroblasts in vitro.

METHOD

Primary cell lines were obtained by explants from Dupuytren's tissue (n = 6), non-diseased palmar fascia from patients with Dupuytren's disease (n = 3) and carpal ligament from patients undergoing carpal tunnel release (n = 3). The effect of 5-fluorouracil on proliferation was assessed by cell counting. Myofibroblast differentiation, an intergral part of Dupuytren's contracture, was investigated by staining for alpha smooth muscle actin, a marker for contractile cells, using immunohisto-chemical methods.

RESULTS

A single exposure to 5-fluorouracil caused a sustained inhibition of proliferation in Dupuytren's and non-diseased fascia cultures, whilst the effect on carpal ligament cultures was transient. Untreated Dupuytren's fibroblasts exhibited the highest myofibroblast differentiation, whilst differentiation in non-diseased fascia cultures was shown to be proportional to cell density and virtually non-existent in carpal ligament cultures. After 5-fluorouracil exposure, the differentiation was significantly reduced in Dupuytren's fibroblasts cultures, reduced at high cell densities in non-diseased fascia and unchanged in carpal ligament cell cultures.

DISCUSSION

5-fluorouracil inhibits both proliferation and myofibroblast differentiation in Dupuytren's cell cultures and may have a potential use as an adjuvant treatment to Dupuytren surgery in order to reduce the rate of recurrence and contracture.

Vocational students' learning preferences: the interpretability of ipsative data

A number of researchers have argued that ipsative data are not suitable for statistical procedures designed for normative data. Others have argued that the interpretability of such analyses of ipsative data are little affected where the number of variables and the sample size are sufficiently large. The research reported here represents a factor analysis of the scores on the Canfield Learning Styles Inventory for 1,252 students in vocational education. The results of the factor analysis of these ipsative data were examined in a context of existing theory and research on vocational students and lend support to the argument that the factor analysis of ipsative data can provide sensibly interpretable results.

A community-level HIV prevention intervention for inner-city women: results of the women and infants demonstration projects

OBJECTIVES

This study examined the effects of a multisite community-level HIV prevention intervention on women's condom-use behaviors.

METHODS

The theory-based behavioral intervention was implemented with low-income, primarily African American women in 4 urban communities. It was evaluated with data from pre- and postintervention cross-sectional surveys in matched intervention and comparison communities.

RESULTS

At baseline, 68% of the women had no intention of using condoms with their main partners and 70% were not using condoms consistently with other partners. After 2 years of intervention activities, increases in rates of talking with main partners about condoms were significantly larger in intervention communities than in comparison communities (P = .03). Intervention communities also had significant increases in the proportion of women who had tried to get their main partners to use condoms (P = .01). The trends for condom use with other partners were similar but nonsignificant.

CONCLUSIONS

Many women at risk for HIV infection are still not using condoms. Community-level interventions may be an effective way to reach large numbers of women and change their condom-use behaviors, particularly their behaviors with regard to communication with main sex partners.

Intraoral distraction osteogenesis in the baboon mandible using a tooth and bone-anchored appliance

PURPOSE

The purpose of this study was to determine the feasibility of using an intraoral, bone and tooth-anchored appliance to distract baboon mandibles using the principles of distraction osteogenesis (DO).

MATERIALS AND METHODS

Seven juvenile baboons were used in this study. Mandibular corticotomies were made in the ramus of the mandible unilaterally (n = 5) or bilaterally (n = 2), and a "pin-in-tube" (PIT) distraction appliance was applied. The device was secured to the mandibular ramus posterior to the cortical cut with a bicortical screw and anteriorly to an occlusal splint. The appliance was activated an average of 0.86 mm/d (0.5 to 1.3 mm/d) for an average of 12.4 days (10 to 14 days). Predistraction and postdistraction measurements were made between metallic markers placed in the distraction area, in the dental midline, and of the overjet and overbite.

RESULTS

Bone healing was complete in all mandibles. The average mandibular lengthening measured between the metallic markers was 7.9 mm. The mandibular midlines showed an average of 4.25 mm of lateral movement in the unilaterally distracted mandibles. There were no infections.

CONCLUSIONS

The results of this study indicate that an intraoral bone and tooth-anchored distraction appliance is an effective method to produce lengthening in the mandible by distraction osteogenesis.

Imaging of the normal and abnormal pancreaticobiliary system with single-shot MR cholangiopancreatography: a pictorial review

Magnetic resonance cholangiopancreatography (MRCP) is a rapidly evolving non-invasive imaging modality that produces images of the pancreatic duct and biliary tree without the need for intravenous or oral contrast. The images are equivalent to those from endoscopic retrograde cholangiopancreatography (ERCP), but the non-invasive acquisition avoids the morbidity and mortality associated with diagnostic ERCP. Magnetic resonance cholangiopancreatography is indicated in patients who require only a diagnostic ERCP, who fail an ERCP or who are unable to undergo ERCP due to altered post-surgical anatomy. Other evolving indications include triaging of patients with obstructive jaundice into percutaneous or endoscopic management drainage pathways depending on the site, length and nature of the duct obstruction, thereby potentially decreasing the number of failed or unsuccessful ERCP. Pre-operative identification of anomalous biliary anatomy and choledocholithiasis prior to laparoscopic cholecystectomy promise to modify the pre-operative and operative management of the patient in order to minimize the risk of duct injury and unnecessary intra-operative dissection and cholangiography. The advantages of the technique include its non-invasiveness, the absence of contrast administration, its relative operator independence and the ability to evaluate both sides of an obstructed duct, thereby accurately evaluating stricture morphology and length. The disadvantages of MRCP compared to ERCP include its lack of an immediate therapeutic solution to duct obstruction, procedural cost, unit availability and the inability to evaluate patients with pacemakers or ferromagnetic implants.

Recent bioequivalence studies on fixed-dose combination anti-tuberculosis drug formulations available on the global market

SETTING

Concern has been expressed about the bioavailability of rifampicin in some fixed-dose combination (FDC) anti-tuberculosis formulations.

OBJECTIVE

To evaluate the relative bioavailability of rifampicin in various FDC formulations currently in use in tuberculosis control programmes in the global market.

DESIGN

A two-period randomised crossover bioequivalence study in healthy male volunteers, with a 1 week washout period between treatments. Plasma rifampicin concentrations were measured at 0, 1, 2, 4, 6, 8 and 12 hours after each drug administration.

RESULTS

The AUC0-8, AUC0-12 and Cmax for rifampicin in seven of 10 FDC formulations was not found to be bioequivalent to the reference administered as loose (separate) formulations. This was confirmed using parametric and non-parametric statistical methods.

CONCLUSIONS

The poor relative bioavailability of rifampicin from some FDCs has been documented. The implications for tuberculosis programmes are extremely serious and warrant urgent attention.

Determination of rifampicin, isoniazid and pyrazinamide by high performance liquid chromatography after their simultaneous extraction from plasma

SETTING

Isoniazid (INH), rifampicin (RIF), and pyrazinamide (PZA) are first-line antituberculosis drugs. Due to difficulties in producing effective combined formulations of these three drugs, the bioavailability of new combination formulations needs to be assessed prior to registration.

OBJECTIVE

To develop a rapid, simple and sensitive high performance liquid chromatography (HPLC) assay method suitable for assaying RIF, INH and PZA in large numbers of plasma samples generated in bioavailability studies.

METHOD

RIF, desacetyl-rifampicin (DRIF), INH and PZA were extracted simultaneously from plasma using a solid phase extraction column. RIF and DRIF were quantitated by HPLC using an 80% acetonitrile/0.1% trifluoroacetic acid (TFA) mobile phase and a C8 reversed phase column. INH and PZA were also quantitated on a C8 reversed phase column, but a 3% acetonitrile/0.6% TFA mobile phase was used.

RESULTS

Mean recovery of RIF, DRIF and PZA from plasma was well over 90%, and over 70% for INH. Calibration graphs were linear for all the drugs in their therapeutic range. Correlation coefficients were all above 0.9995, and between- and within-run coefficients of variation below 10%.

CONCLUSION

A simple, accurate, sensitive and cost effective assay for first-line antituberculosis drugs has been developed.

Peroxisome proliferator-activated receptor gamma activation in human breast cancer

The peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear receptor family of ligand-activated transcription factors. This study was designed to evaluate ligand activation of PPARgamma in human breast cancer cells. DNA binding by endogenous PPARgamma in gel shift assays and activation of PPARgamma by prostanoid and thiazolidinedione ligands in reporter gene assays differed between the cell lines. The PPARgamma ligands elicited an anti-proliferative effect in MTT proliferation assays. Our data point to a variable, cell-specific response to different gamma-ligands, which holds significance for further studies on the role of PPARgamma in mediating breast cancer growth and progression.

The development of a standardised screening protocol for the in vivo assessment of rifampicin bioavailability

SETTING

The prerequisite for in vivo bioavailability testing of rifampicin in fixed-dose combination (FDC) formulations is widely accepted. However, many smaller drug regulatory authorities and drug manufacturers have difficulty implementing costly and cumbersome testing procedures.

OBJECTIVE

To test whether a simplified blood sampling schedule can be used for the determination of drug bioequivalence in randomised, single dose, crossover studies of FDCs and appropriate reference formulations.

METHOD

The results of three bioavailability and bioequivalence studies of different rifampicin-containing FDCs were analysed. The relationship between the number of time points employed and precision of estimated relative bioavailability was explored. The relative bioavailabilities of the drug components in the test FDCs were calculated using maximal concentration and area under the curve estimates based on an extended blood sampling schedule of up to 15 time points over 48 hours, and a contracted sampling scheme with only six blood samples over 8 hours.

RESULTS

Estimates of relative bioavailability calculated using the contracted blood sampling protocol were closely similar to those derived using the extended sampling schedules.

CONCLUSION

Considerable cost and convenience benefits can be gained by using the contracted sampling schedule with only a minor reduction in the precision of the estimation of relative rifampicin bioavailability.

A novel cell permeant and far red-fluorescing DNA probe, DRAQ5, for blood cell discrimination by flow cytometry

The deep red fluorescing agent (DRAQ5) is a synthetic anthraquinone with a high affinity for DNA and a high capacity to rapidly enter living cells or stain fixed cells. DRAQ5 is optimally excited by red-light emitting sources and yields a deep red emission spectrum which extends into the low infra-red. DRAQ5 shows excitation at sub-optimal wavelengths including the 488 nm line and the multi-line UV wavelengths emitted by argon-ion lasers. Single beam (488 nm) flow cytometry has been used to demonstrate the utility of DRAQ5-nuclear DNA fluorescence as a discriminating parameter for human leucocytes and lymphoma cells, in combination with fluorochrome-labelled antibodies for the detection of surface antigens and subpopulation recognition. DRAQ5 fluorescence was found to reflect cellular DNA content as evidenced by cell cycle distribution profiles for asynchronous and cell cycle-perturbed populations. Importantly, DRAQ5 can be used in combination with FITC and RPE-labelled antibodies, without the need for fluorescence compensation.

Oxygen-depleted zones inside reproductive structures of Brassicaceae: implications for oxygen control of seed development

Growth of Arabidopsis thaliana (L.) Heynh. in decreasing oxygen partial pressures revealed a linear decrease in seed production below 15 kPa, with a complete absence of seed production at 2.5 kPa oxygen. This control of plant reproduction by oxygen had previously been attributed to an oxygen effect on the partitioning between vegetative and reproductive growth. However, plants grown in a series of decreasing oxygen concentrations produced progressively smaller embryos that had stopped developing at progressively younger stages, suggesting instead that their growth is limited by oxygen. Internal oxygen concentrations of buds, pistils, and developing siliques of Brassica rapa L. and siliques of Arabidopsis were measured using a small-diameter glass electrode that was moved into the structures using a micromanipulator. Oxygen partial pressures were found to be lowest in the developing perianth (11.1 kPa) and pistils (15.2 kPa) of the unopened buds. Pollination reduced oxygen concentration inside the pistils by 3 kPa after just 24 h. Inside Brassica silique locules, partial pressures of oxygen averaged 12.2 kPa in darkness, and increased linearly with increasing light levels to 16.2 kPa. Measurements inside Arabidopsis siliques averaged 6.1 kPa in the dark and rose to 12.2 kPa with light. Hypoxia in these microenvironments is postulated to be the point of control of plant reproduction by oxygen.

Is Dupuytren's disease caused by an imbalance between proliferation and cell death?

Dupuytren's contracture shares certain properties with malignant tumours, characterized by proliferation and lack of apoptosis, which may be induced by the c-myc oncogene. Because of these similarities, the relationship between the c-myc oncogene expression, bcl-2 oncogene (anti-apoptotic gene) and proliferation was investigated in Dupuytren's disease. Proliferation was assessed by immunohistochemical staining of the mib-1 antibody. Results were compared with those from fibrosarcoma specimens, representing a related malignant tumour. Non-diseased fascia from Dupuytren patients and flexor retinaculum from patients undergoing carpal tunnel release without Dupuytren's disease were used as controls. Expression of c-myc was elevated in primary Dupuytren's disease and fibrosarcoma specimens, whilst recurrent Dupuytren's disease, non-diseased Dupuytren fascia and flexor retinaculum exhibited significantly lower levels. Neither bcl-2 nor mib-1 were detected in Dupuytren's disease, non-diseased fascia or flexor retinaculum, in contrast to fibrosarcoma. The imbalance between proliferation and apoptosis, producing malignant growth was thus confirmed for fibrosarcoma, but not for Dupuytren's disease.

Self-referencing, non-invasive, ion selective electrode for single cell detection of trans-plasma membrane calcium flux

Biological systems have very different internal ion compositions in comparison with their surrounding media. The difference is maintained by transport mechanisms across the plasma membrane and by internal stores. On the plasma membrane, we can classify these mechanisms into three types, pumps, porters, and channels. Channels have been extensively studied, particularly since the advent of the patch clamp technique, which opened new windows into ion channel selectivity and dynamics. Pumps, particularly the plasma membrane Ca(2+)-ATPase, and porters are more illusive. The technique described in this paper, the self-referencing, ion-selective (or Seris) probe, has the ability to monitor the behavior of membrane transport mechanisms, such as the pumps and porters, in near to real-time by non-invasively measuring local extracellular ion gradients with high sensitivity and square micron spatial resolution. The principles behind the self-referencing technique are described with an overview of systems utilizing ion, electrochemical and voltage sensors. Each of these sensors employs the simple expedient of increasing the system resolution by self-referencing and, thereby, removing the drift component inherent to all electrodes. The approach is described in detail, as is the manner in which differential voltage measurements can be converted into a flux value. For the calcium selective probes, we can resolve flux values in the low to sub pmol.cm(-2)s(-1) range. Complications in the use of the liquid ion exchange cocktail are discussed. Applications of the calcium selective probe are given, drawing on examples from the plant sciences, developmental biology, muscle physiology, and the neurosciences.

Cell cycle checkpoint evasion and protracted cell cycle arrest in X-irradiated small-cell lung carcinoma cells

PURPOSE

To determine the longevity and dose-dependence of acute X-irradiation-induced cell cycle perturbations in a panel of seven small-cell lung carcinoma (SCLC) cell lines (COR-L32B, COR-L51B, COR-L88B, COR-L96C, COR-L103, COR-L266B, COR-L279), assessed for TP53 tumour suppressor gene status and showing characteristically long population doubling periods.

MATERIALS AND METHODS

Cell lines were screened for abnormalities in TP53. Cell cycle arrest and nuclear fragmentation were determined by flow cytometry under culture conditions that minimized the propensity of SCLC cells to form multicellular aggregates. A faster growing SCLC cell line (NCI-H69) and two breast tumour cell lines were used as controls.

RESULTS

NCI-H69 and five of the COR-SCLC cell lines showed clear evidence of TP53 abnormalities and the cycle arrest responses of the breast tumour cell lines established the effects of TP53 mutation on G1/S checkpoint loss. All SCLC lines, at 24 h after low dose irradiation, showed abrogation of the G1/S checkpoint together with a range of expression of a protracted G2/M delay. G2/M delay progressed in all panel cell lines up to 48 h post-irradiation while NCI-H69 showed significant recovery for the dose range 75-600cGy. Only NCI-H69 and one panel line showed dose-dependent progression to complete nuclear DNA fragmentation.

CONCLUSIONS

The culture method permits the measurement of cell cycle effects that reflect the TP53 status of SCLC cells. G1/S checkpoint failure, long-term radiation-induced G2 arrest, highly muted apoptotic responses and delayed recovery appear to be typical responses of the recently derived COR-SCLC lines. The results imply that low levels of unrepaired DNA damage, induced at clinically relevant doses, can persist for days in SCLC cells with long cell cycle traverse times, and can remain capable of checkpoint activation with implications for S phase-targeted therapies.

Arrangement of radial actin bundles in the growth cone of Aplysia bag cell neurons shows the immediate past history of filopodial behavior

Filopodia that protrude forward from the lamellipodium, located at the leading edge of a neuronal growth cone, are needed to guide the extension of a nerve cell. At the core of each filopodium an actin bundle forms and grows into the lamellipodium. By using kymographs of time-lapse polarized light images we examined the relationship between the behavior of the filopodia, the actin bundles immediately proximal to the filopodia, and the shapes and composition of actin bundles in the whole lamellipodium. We find that the shapes of actin bundles, such as tilt, fork, and fused zones, originate at the leading edge and are surprisingly well preserved during retrograde transport of the actin cytoskeleton in the whole lamellipodium. The number of filaments that make up the radial actin bundles, as displayed by their birefringence retardation, also is preserved during retrograde flow over a distance of 4-8 microm from the leading edge into the lamellipodium. Thus, the disposition of the actin bundles in the lamellipodium frozen at any time point preserves and portrays a history of the past behavior of actin bundles proximal to the filopodia and the behavior of the filopodia themselves. These findings suggest that the arrangement of actin bundles in static image records, such as electron or fluorescence micrographs of fixed and stained specimens, can in fact reveal the sequence of the past history of filopodial behavior and the generation, density, fusion, etc. of the filaments in the actin bundles.

The effect of artesunate combined with standard antimalarials against chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum in vitro

The interactions of artesunate with chloroquine, mefloquine, quinine, doxycycline and pyrimethamine were tested in vitro against chloroquine-sensitive (D10) and chloroquine-resistant (RSA11) strains of Plasmodium falciparum. Mefloquine and quinine both showed synergism of artesunate activity against each of the strains, whilst doxycycline showed an additive interaction. Pyrimethamine combinations were antagonistic, and the combination of artesunate with chloroquine was antagonistic against RSA11, and additive against D10. Although weak antagonism in vitro might not indicate any clinical significance, synergism with artesunate may increase the clinical usefulness of either drug, and could potentially be of value in delaying the emergence of resistance.

CDKN1C expression in Beckwith-Wiedemann syndrome patients with allele imbalance

In this study, we have examined CDKN1C expression in BWS patients with allele imbalance (AI) affecting the 11p15 region. Two of two informative patients with AI, attributable to mosaic paternal isodisomy, exhibited reduced levels of CDKN1C expression in the liver and kidney, respectively, relative to expression levels in the equivalent tissues in normal controls. Although overall expression was reduced, some expression from the paternally derived CDKN1C allele was evident, consistent with incomplete paternal imprinting of the gene. One patient showed evidence of maternal allele silencing in addition to AI. These findings show for the first time that CDKN1C expression is reduced in BWS patients with AI and suggest that CDKN1C haploinsufficiency contributes to the BWS phenotype in patients with mosaic paternal isodisomies of chromosome 11.

A prospective comparative study of the AMO ARRAY zonal-progressive multifocal silicone intraocular lens and a monofocal intraocular lens

OBJECTIVE

To evaluate the safety and effectiveness of a zonal-progressive multifocal silicone intraocular lens (IOL).

DESIGN

Prospective, nonrandomized, fellow eye comparative trial.

PARTICIPANTS

Four hundred fifty-six subjects were enrolled at 14 investigational sites in the United States; 400 subjects achieved 1-year follow-up. A subset of 123 subjects (102 at 1 year) were enrolled in a monofocal fellow eye control substudy; subjects were implanted with the multifocal IOL in one eye and a comparable monofocal IOL in the fellow eye.

METHODS

Cataract extraction and implantation of a zonal-progressive multifocal silicone IOL was performed using the surgeon's standard technique. Subjects were followed at six postoperative examination intervals through 1 year.

MAIN OUTCOME MEASURES

The key efficacy measures were mean uncorrected and corrected distance and near visual acuity at 1 year after surgery.

RESULTS

In the monofocal fellow eye control substudy, the multifocal eyes showed a mean 2-line increase over monofocal eyes for uncorrected and distance-corrected near visual acuity (P < 0.0001). Mean uncorrected distance visual acuity was similar between multifocal and monofocal eyes (P = 0.116). A significantly higher proportion of bilateral multifocal subjects reported that they could function comfortably without glasses at near (81%, 96 of 118) compared with multifocal/monofocal subjects (56%; 93 of 165; P < 0.001) and unilateral multifocal subjects (58%; 56 of 97; P < 0.001). Low-contrast visual acuity was reduced in multifocal eyes by approximately 1 Snellen line. However, no perceived disadvantages attributable to the reduction in low-contrast acuity were found. Although the perception of halos and glare increased in the multifocal eyes, good visual function remained, and nearly all subjects were satisfied with the results of their surgery.

CONCLUSIONS

In a large study that included a subset of subjects with paired eye compared with those with monofocal lenses, this zonal-progressive multifocal lens provided a high level of uncorrected and corrected distance vision, improved uncorrected and distance-corrected near vision, reduced spectacle dependency, and a high level of patient satisfaction despite some loss of low-contrast visual acuity and increased reports of halos and glare.

Stage-dependent effects of epidermal growth factor on Ca2+ efflux in mouse oocytes

Epidermal growth factor (EGF) has received much attention recently for its positive effects on mammalian oocyte maturation and embryo development and its potential importance in cytoplasmic maturation of oocytes. Calcium (Ca2+) homeostasis in germinal vesicle stage oocytes has also been suggested to play a role in cytoplasmic maturation. This study examined the effects of EGF on Ca2+ mobilization as measured by its efflux from mouse oocytes at three time periods throughout maturation (0-4 hr, 4-8 hr, and 12 hr). Immature cumulus oocyte complexes (COCs) removed from the ovary for less than 4 hr exhibit oscillations in Ca2+ efflux that initiated 5-30 min following EGF stimulation. This response was not observed in COCs matured for 4-8 hr or 12 hr or in unstimulated 0-4 hr COCs. Denuded oocytes and cumulus cells did not show the same response to EGF (8.2 nM and 16.4 nM). Immunohistochemistry for detection of the EGF receptor along with EGF internalization studies showed that receptors are present both on cumulus cells and the oocyte but EGF appears to be internalized mainly by the cumulus cells. These data demonstrate that EGF induces oscillations in Ca2+ efflux in COCs 0-4 hr old and this response is mediated by the cumulus cells.

Anomalous extensor muscles of the hand: a review

Anomalous extensor muscles of the hand are not uncommon. Well-recognized anomalies anomalous extensor indicis proprius, extensor digitorum brevis manus, extensor medii proprius, and extensor indicis et medii communis are reviewed and discussed in detail. Anomalous extensor indicis proprius and extensor digitorum brevis manus may occasionally give rise to dorsal wrist pain and the diagnosis is often confused especially in the presence of other pathologic findings such as a ganglion. An analysis of the embryologic development of the extensor muscle mass with phylogenetic comparisons between species of the animal kingdom is presented to underscore the clinical relevance of these anomalous extensors.

Transmembrane regulation of intracellular calcium by a plasma membrane sodium/calcium exchanger in mouse ova

Regulation of cytoplasmic free calcium concentration ([Ca2+)]i) is a key factor for maintenance of viability of cells, including oocytes. Indeed, during fertilization of an ovum, [Ca2+]i is known to undergo oscillations, but it is unknown how basal [Ca2+]i or calcium oscillations are regulated. In the present study we investigated the role of the plasma membrane in regulating [Ca2+]i of metaphase II-arrested mouse oocytes (ova). Ova were collected from B6C3F1 mice treated with eCG (10 IU) and hCG (5 IU), and intracellular calcium was determined by means of fura-2. Extracellular calcium flux across the zona pellucida was detected noninvasively by a calcium ion-selective, self-referencing microelectrode that was positioned by a computer-controlled micromanipulator. Under basal conditions ova exhibited a calcium net efflux of 20.6 +/- 5.2 fmol/cm2 per sec (n = 69). Treatment of ova with ethanol (7%) or thapsigargin (25 nM-2.5 microM) transiently increased intracellular calcium and stimulated calcium efflux that paralleled levels of [Ca2+]i. The presence of a Na+/Ca2+ exchanger was indicated by experiments employing both bepridil, an inhibitor of Na+/Ca2+ exchange, and sodium-depleted media. In the presence of bepridil, a net influx of calcium was revealed across the zona pellucida, which was reflected by an increase in the [Ca2+]i. In addition, replenishment of extracellular sodium to ova that had been incubated in sodium-depleted media induced a large calcium efflux, consistent with the actions of Na+/Ca2+ exchange. Sodium/calcium exchange in mouse ova may be an important mechanism that regulates [Ca2+]i.

Impaired cholinergic dilator response of resistance arteries isolated from patients with Raynaud's disease

AIMS

We examined the effect of cooling on the response to the endothelium-dependent and -independent dilators, acetylcholine (ACh) and sodium nitroprusside (SNP), respectively, in human microvessels in vitro, and compared the responses between Raynaud's disease (RD) patients and controls, in order to assess the pathogenic role of the endothelium in RD.

METHODS

Subcutaneous resistance arteries were dissected from gluteal fat biopsies taken from patients with RD (n=18) and from age-and sex-matched control subjects (n=17). Vessels were cannulated in a small vessel arteriograph, in which a pressure of 50 mmHg was maintained across the vessel wall. Cumulative concentration-response curves for ACh (10-10-10-4 m ) and SNP (10-10-10-3 m ) were generated in vessels at either 37 degrees C or 24 degrees C, with endothelium intact for ACh and removed for SNP (n=6 per group).

RESULTS

Neither dilator showed significant differences in sensitivity when comparing responses between vessels from RD patients and controls, at either temperature, but the maximal relaxation to ACh was depressed in vessels from RD patients compared with controls at 37 degrees C (Emax=45+/-13 in RD vs 89+/-4 in controls; P=0.004).

CONCLUSIONS

These results support the hypothesis that impaired endothelium-dependent vasodilatation is involved in the pathophysiology of RD.

Non-traumatic spinal extradural haematoma: magnetic resonance findings

Non-traumatic extradural spinal haematoma is an uncommon condition that is usually associated with a poor outcome. It may present acutely with signs and symptoms of major neurological dysfunction secondary to cord compression, or subacutely over a number of days or weeks with fluctuating symptoms. The exact aetiology of this condition is incompletely understood, but it is believed that the blood is venous in origin, as distinct from the arterial origin of intracranial extradural haematomas. Causes of non-traumatic extradural spinal haematoma include anticoagulation, vasculitis such as systemic lupus erythematosus (SLE), and spinal arteriovenous malformations. Conditions that may mimic an acute spinal haematoma include extradural abscess and extradural metastatic infiltration. It is important to make a diagnosis of extradural compression because surgery may offer the best hope in restoring neurological function in these patients. Imaging modalities used for the investigation of extradural haematomas include myelography, CT myelography (CTM) and MRI with or without gadolinium enhancement. The MR appearances of acute extradural abscess and extradural tumour can mimic an extradural haematoma. In subacute haematoma, owing to the magnetic properties of blood degradation products, MR is more specific in diagnosing and ageing of the haematoma.

Enzymatic grafting of a natural product onto chitosan to confer water solubility under basic conditions

Chitosan is a natural biopolymer whose rich amine functionality confers water solubility at low pH. At higher pH's (greater than 6. 5), the amines are deprotonated and chitosan is insoluble. To attain water solubility under basic conditions we enzymatically grafted the hydrophilic compound chlorogenic acid onto chitosan. Despite its name, chlorogenic acid is a nonchlorinated phenolic natural product that has carboxylic acid and hydroxyl functionality. The enzyme in this study was tyrosinase, which converts a wide range of phenolic substrates into electrophilic o-quinones. The o-quinones are freely diffusible and can undergo reaction with the nucleophilic amino groups of chitosan. Using slightly acidic conditions (pH = 6), it was possible to modify chitosan under homogeneous conditions. When the amount of chlorogenic acid used in the modification reaction exceeded 30% relative to chitosan's amino groups, the modified chitosan was observed to be soluble under both acidic and basic conditions, and to have a pH window of insolubility at near neutral pH. 1H NMR spectra confirmed that chitosan was chemically modified, although the degree of modification was low. Copyright 1999 John Wiley & Sons, Inc.

Control of replicative life span in human cells: barriers to clonal expansion intermediate between M1 senescence and M2 crisis

The accumulation of genetic abnormalities in a developing tumor is driven, at least in part, by the need to overcome inherent restraints on the replicative life span of human cells, two of which-senescence (M1) and crisis (M2)-have been well characterized. Here we describe additional barriers to clonal expansion (Mint) intermediate between M1 and M2, revealed by abrogation of tumor-suppressor gene (TSG) pathways by individual human papillomavirus type 16 (HPV16) proteins. In human fibroblasts, abrogation of p53 function by HPVE6 allowed escape from M1, followed up to 20 population doublings (PD) later by a second viable proliferation arrest state, MintE6, closely resembling M1. This occurred despite abrogation of p21(WAF1) induction but was associated with and potentially mediated by a further approximately 3-fold increase in p16(INK4a) expression compared to its level at M1. Expression of HPVE7, which targets pRb (and p21(WAF1)), also permitted clonal expansion, but this was limited predominantly by increasing cell death, resulting in a MintE7 phenotype similar to M2 but occurring after fewer PD. This was associated with, and at least partly due to, an increase in nuclear p53 content and activity, not seen in younger cells expressing E7. In a different cell type, thyroid epithelium, E7 also allowed clonal expansion terminating in a similar state to MintE7 in fibroblasts. In contrast, however, there was no evidence for a p53-regulated pathway; E6 was without effect, and the increases in p21(WAF1) expression at M1 and MintE7 were p53 independent. These data provide a model for clonal evolution by successive TSG inactivation and suggest that cell type diversity in life span regulation may determine the pattern of gene mutation in the corresponding tumors.

High incidence of treatment failure with vincristine, etoposide, epirubicin, and prednisolone chemotherapy with successful salvage in childhood Hodgkin disease

BACKGROUND AND PROCEDURE

In an attempt to further reduce the long-term toxicity of chemotherapy for childhood Hodgkin disease (HD), the Australian and New Zealand Children's Cancer Study Group between 1990 and 1996 enrolled 53 children with biopsy-proven and imaging-staged HD into a chemotherapy-only treatment regimen using 5-6 courses of vincristine, etoposide, epirubicin, and prednisolone (VEEP).

RESULTS

There were 23 events in these children with 3 progressive disease (PD), 8 partial remissions (PR), and 12 relapses. In the stage I patients, there were 8 events (35%). There was no association between the number of events and the stage of HD. Massive mediastinal disease at diagnosis was present in 16 patients, 11 of whom had an event with 3 PD, 3 PR, and 5 relapses. For all patients with an event at 6-24-month follow-up, all but two patients were salvaged with either alkylating agent-based chemotherapy alone or with irradiation and chemotherapy. The event-free survival for the whole group with median follow-up of 33 months was 59%, but only 31% for massive mediastinal disease. Disease-free survival was 78% and overall survival at 60 months was 92%, with one death due to drug-induced aplasia and another from acute myeloid leukemia.

CONCLUSIONS

We conclude that VEEP chemotherapy in childhood HD used as the only treatment modality has an unacceptably high treatment failure rate in patients with massive mediastinal disease and 35% incidence of treatment failure in stage I disease.