The in vitro effect of pegylated recombinant human megakaryocyte growth and development factor (PEG rHuMGDF) on megakaryopoiesis in normal subjects and patients with myelodysplasia and acute myeloid leukaemia

Mpl ligand is a recently cloned haemopoietic growth factor that stimulates megakaryopoiesis in vitro and in vivo. We describe the in vitro effect of a truncated form of Mpl ligand, recombinant human megakaryocyte growth and development factor (rHuMGDF), on megakaryopoiesis in bone marrow from normal subjects and patients with myelodysplastic syndrome (MDS) and acute myeloid leukaemia (AML). We used both semi-solid and suspension culture techniques to assess the effect of pegylated (PEG) rHuMGDF on megakaryocyte colony growth (CFU-Mk) and on the production of CD61+ cells in 7d suspension cultures. PEG rHuMGDF increased CFU-Mk growth and CD61+ cell production in a dose-dependent fashion in all normal marrows tested. Normal CFU-Mk growth was increased threefold with the addition of 10 ng/ml PEG rHuMGDF to cultures and CD61+ cells were increased 8-10-fold by the same dose. Although increased CFU-Mk growth was only seen in 1/10 AML and 6/16 MDS marrows, CD61+ cell numbers in suspension culture were increased in 9/13 AML and 12/15 MDS samples, responses ranged from very limited to normal magnitude. There was no correlation between platelet count and CFU-Mk number, CD61+ cell number or response to PEG rHuMGDF. We did not find any increased CFU-GM colony or cluster growth in response to PEG rHuMGDF and the CD61+ cells produced in suspension culture had features of megakaryocytic differentiation. These data suggest that PEG rHuMGDF can enhance megakaryocyte proliferation in some patients with MDS and AML, and may have a role in the treatment of thrombocytopenia in these patients.

Effect on cell kill of addition of multidrug resistance modifiers cyclosporin A and PSC 833 to cytotoxic agents in acute myeloid leukaemia

Multidrug resistance (MDR) mediated by the drug efflux pump P-glycoprotein (Pgp), may cause remission failure and relapse in patients with acute myeloid leukaemia (AML) by extruding cytotoxic agents such as anthracyclines from leukaemic cells thus allowing them to survive. Cell line data suggest that reversal of MDR is possible using modifying drugs such as cyclosporin A (CSA) and its analogue PSC 833. We have investigated the effects on cell kill of the addition of CSA and PSC 833 to daunorubicin, idarubicin, mitozantrone, etoposide and cytarabine in 52 fresh cell samples from AML patients using an MTT assay. Pgp status was determined by using monoclonal antibodies JSB-1 and MRK-16 and by assessment of rhodamine efflux. Although overall each cytotoxic-modifier combination produced significant improvements in cell kill compared to cytotoxic alone (P values ranged from P < 0.001 to P = 0.017), modifiers also produced significant cytotoxicity in their own right, and no consistent difference was seen between responses in Pgp-positive and negative groups. Up to one in three Pgp-positive samples failed to show any improvement in cell kill with the addition of CSA or PSC 833, possibly owing to co-expression of alternative resistance mechanisms not affected by the MDR modifiers. The best responses were seen when PSC 833 was added to idarubicin, with 7 out of 22 Pgp-positive cases (32%) showing five-fold improvements in cell kill or better compared to idarubicin alone. Comparison of equimolar concentrations of the two modifiers in the Pgp positive group failed to show a significant difference in cell kill, though PSC 833 was markedly superior to CSA in a minority of highly responsive samples which demonstrated clear evidence of MDR reversal. Our in vitro data suggest that MDR modifiers such as CSA and PSC 833 could play an important role in the therapy of AML and indicate the need for prospective randomised trials to assess their clinical efficacy.

The effect of cardiopulmonary bypass on circulating megakaryocytes

Megakaryocytes (Mks) are found in the lungs and the blood stream as well as in the bone marrow. We modified a whole blood filtration method for Mks by immunostaining for CD61 using biotin streptavidin, and used this technique to study Mks and their morphology in the central venous and arterial circulations before, during and after cardiopulmonary bypass (CPB) in haematologically normal patients undergoing routine cardiac surgery. Blood samples were taken immediately after the insertion of central venous (V) and arterial (A) catheters and after thoracotomy, immediately before bypass. Further samples were taken after 60-90 min on-CPB and 180-240 min post-bypass. In comparison with the steady state before bypass, circulating Mk levels in blood on bypass increased dramatically, from (V) 10.93 +/- 3.94/ml (mean +/- SD) to 36.48 +/- 11.52/ml and from (A) 8.37 +/- 4.39/ml to 38.65 +/- 20.68/ml. This effect was still present, to a lesser extent, 180-240 min post-bypass. Circulating levels of Mks were consistently lower in the arterial circulation than in the venous circulation off bypass, but levels in the two circulations were comparable during CPB, confirming previous suggestions that the lungs are net removers of Mks from the circulation. Type 4 Mks, the largest and most normal morphologically, were rarely seen in arterial blood, but increased significantly during CPB, indicating that the lungs selectively remove large Mks. The lungs appear to play an active role in the regulation of Mk levels. This is lost during CPB and despite the extracorporeal 40 microm arterial line filter, large Mks enter the systemic circulation. More effective extracorporeal filtration of large Mks might reduce the neurological impairment seen in some patients who have undergone CPB.

Protection of sensitive patient-connected medical devices from the subversive use of mobile telecommunication equipment

The UK Department of Health has recently advised caution with respect to the uncontrolled use of private mobile telecommunication equipment in designated sensitive hospital areas. This advice, which has clear implications for patient safety and well being, was issued following reports of the interference of automatic drug delivery devices, infusion pumps and other sensitive systems. The difficulty of monitoring relatives, visitors and, occasionally, staff who use such mobile telephones in the sensitive areas has led to an initiative by The Princess Margaret Hospital to automatically and continuously monitor the frequencies used by the mobile telephones and to initiate an alarm should such phones be used within a designated area. This paper describes a protocol for the use of these monitors developed in the Princess Margaret Hospital which is designed to minimize the number of monitoring units while providing optimum departmental cover.

Colony counting is a major source of variation in CFU-GM results between centres

The results for colony forming unit granulocyte-macrophage (CFU-GM) assays vary substantially between centres. It is possible that colony counting is largely responsible for this discrepancy. In order to examine this exclusively from the many factors that make up the CFU-GM assay, we performed a colony counting exercise involving 11 laboratories. Two-way analysis of variance showed a highly significant difference (P = 0.0001) in the counts obtained from the centres. One centre was found to score consistently high and two others scored consistently low numbers of colonies. This suggests that identification of colonies is a major source of variation between centres.

Usher's syndrome type IC: clinical studies and fine-mapping the disease locus

Usher's syndrome type I is a heterogeneous group of diseases characterized by severe to profound sensorineural hearing loss, absent vestibular function, and progressive pigmentary retinopathy. Other identifying clinical features have not been documented. In this study, we examined olfactory acuity, plasma levels of polyunsaturated fatty acids and sarcosine, and cilia ultrastructure in a homogeneous cohort of patients with Usher's syndrome type IC. The normal age-dependent decline in olfactory acuity was observed, and normal plasma levels of polyunsaturated fatty acids and sarcosine were found. However, the incidence of compound cilia in biopsies from the inferior turbinate was significantly higher than that reported in control populations. By reconstructing haplotypes in affected persons. D11S902 and D11S1310 were identified as flanking markers over an interval that contains a candidate gene, KCNC1. No mutations in the coding sequence of this gene could be demonstrated in affected persons.

Requirement of the paraxis gene for somite formation and musculoskeletal patterning

The segmental organization of the vertebrate embryo is first apparent when somites form in a rostrocaudal progression from the paraxial mesoderm adjacent to the neural tube. Newly formed somites appear as paired epithelial spheres that become patterned to form vertebrae, ribs, skeletal muscle and dermis. Paraxis is a basic helix-loop-helix transcription factor expressed in paraxial mesoderm and somites. Here we show that in mice homozygous for a paraxis null mutation, cells from the paraxial mesoderm are unable to form epithelia and so somite formation is disrupted. In the absence of normal somites, the axial skeleton and skeletal muscle form but are improperly patterned. Unexpectedly, however, we found that formation of epithelial somites was not required for segmentation of the embryo or for the establishment of somitic cell lineages. These results demonstrate that paraxis regulates somite morphogenesis, and that the function of somites is to pattern the axial skeleton and skeletal muscles.

Paraxis: a basic helix-loop-helix protein expressed in paraxial mesoderm and developing somites

During vertebrate embryogenesis, cells from the paraxial mesoderm coalesce in a rostral-to-caudal progression to form the somites. Subsequent compartmentalization of the somites yields the sclerotome, myotome, and dermatome, which give rise to the axial skeleton, axial musculature, and dermis, respectively. Recently, we cloned a novel basic helix-loop-helix (bHLH) protein, called scleraxis, which is expressed in the sclerotome, in mesenchymal precursors of bone and cartilage, and in connective tissues. Here we report the cloning of a bHLH protein, called paraxis, which is nearly identical to scleraxis within the bHLH region but diverges in its amino and carboxyl termini. During mouse embryogenesis, paraxis transcripts are first detected at about Day 7.5 postcoitum within primitive mesoderm lying posterior to the head and heart primordia. Subsequently, paraxis expression progresses caudally through the paraxial mesoderm, immediately preceding somite formation. Paraxis is expressed at high levels in newly formed somites before the first detectable expression of the myogenic bHLH genes, and as the somite becomes compartmentalized, paraxis becomes downregulated in the myotome. Paraxis and scleraxis are coexpressed in the sclerotome, but paraxis expression declines soon after sclerotome formation, whereas scleroaxis expression increases in the sclerotome and its derivatives. The sequential expression of paraxis and scleraxis in the paraxial mesoderm and somites suggests that these bHLH proteins may comprise part of a regulatory pathway involved in patterning of the paraxial mesoderm and in the establishment of somitic cell lineages.

Immunostaining of whole agar cultures by APAAP

We have adapted the alkaline phosphatase-anti alkaline phosphatase (APAAP) technique to demonstrate cell antigen distributions in intact agar culture. The method facilitates batch processing and is no less convenient to perform than standard APAAP procedures. Myeloid and lymphoid antigens generally demonstrated strong staining intensity. However, staining at day 0 consistently produced no antigen expression for two monoclonals (CD11c and CD34) in contrast to positivity in parallel cytospins. CD11c showed rapidly increasing antigen expression over subsequent days of culture whereas the expression of CD34 could not be shown in conventional agar culture at any time from day 0 to day 14. Positivity was only restored in CD34-positive leukaemic cells using a modified culture technique in which cells were cultured as pre-formed small aggregates. Assessment of these aggregates extended to cell cycle analysis using anti-bromodeoxyuridine. CD71 positivity in normal culture samples correlated with colony configuration (whether clones were 'spread' or 'tight' in appearance). CD38 staining of normal bone marrow culture at day 7 showed asymmetrical staining of cells in a small number of micro-groups. The clonal detection of aberrant antigens (CD7, CD2) for assessment of minimal residual disease in AML was a disappointment due to the relative frequency of positive clones in normal culture.

PICK1: a perinuclear binding protein and substrate for protein kinase C isolated by the yeast two-hybrid system

Protein kinase C (PKC) plays a central role in the control of proliferation and differentiation of a wide range of cell types by mediating the signal transduction response to hormones and growth factors. Upon activation by diacylglycerol, PKC translocates to different subcellular sites where it phosphorylates numerous proteins, most of which are unidentified. We used the yeast two-hybrid system to identify proteins that interact with activated PKC alpha. Using the catalytic region of PKC fused to the DNA binding domain of yeast GAL4 as "bait" to screen a mouse T cell cDNA library in which cDNA was fused to the GAL4 activation domain, we cloned several novel proteins that interact with C-kinase (PICKs). One of these proteins, designated PICK1, interacts specifically with the catalytic domain of PKC and is an efficient substrate for phosphorylation by PKC in vitro and in vivo. PICK1 is localized to the perinuclear region and is phosphorylated in response to PKC activation. PICK1 and other PICKs may play important roles in mediating the actions of PKC.

Propagation of interictal epileptic activity in temporal lobe epilepsy

We recorded interictal spikes with closely spaced scalp electrodes and sphenoidal electrodes in four patients with temporal lobe epilepsy. We used multiple dipole modeling to study the number, three-dimensional intracerebral location, time activity, and functional relationship of the neuronal sources underlying the epileptic spike complexes. In all patients, we found two significant sources generating the interictal spikes which showed considerable overlap in both space and time. Source 1 was located in the mesiobasal temporal lobe and generated a restricted negativity at the ipsilateral sphenoidal electrode and a widespread positivity over the vertex. Source 2 could be attributed to the lateral temporal neocortex and was associated with a relatively restricted negativity at the ipsilateral temporal electrodes and a more widespread positivity over the contralateral hemisphere. The sources were well separated in space, with an average distance of 45 mm between them. The time activities of both sources showed similar biphasic patterns, with the mesial source leading the lateral source by approximately 40 msec, suggesting propagation of interictal epileptic activity from the mesiobasal to the lateral temporal lobe.

P-glycoprotein expression on acute myeloid leukaemia blast cells at diagnosis predicts response to chemotherapy and survival

P-glycoprotein (Pgp) expression, which is associated with the multi-drug resistance (MDR) phenotype, has been reported to be a useful predictor of treatment outcome in acute leukaemia. We have examined the expression of Pgp on acute myeloid leukaemia (AML) cells in 54 newly diagnosed patients, using a novel streptavidin-biotin complex (ABC) technique. 55% of patients at diagnosis were positive for Pgp with JSB-1, a monoclonal antibody that binds to an internal epitope of Pgp. All patients received intensive induction chemotherapy. Post-remission treatment consisted of further chemotherapy +/- bone marrow transplantation. Complete remission (CR) rates were significantly lower in the Pgp positive group than in the Pgp negative group (60% v 92%; P = 0.02). The overall survival for Pgp-positive patients was significantly shorter (329 v 534d, P = 0.004), disease-free survival was also reduced but the difference was not statistically significant (median 277 v 522d, P = 0.16). In this study CD34 expression was not predictive of response to chemotherapy nor was it associated with Pgp expression. Our results confirm the prognostic value of Pgp expression in AML at diagnosis and we suggest that Pgp could be a useful therapeutic target for reversing multi-drug resistance. Furthermore, our simple and sensitive method of detecting Pgp should enable widespread testing to be performed.

Increased cytotoxicity of squamous cell carcinoma of the head and neck by combining cisplatin with VP-16 and ciprofloxacin

Chemotherapeutic treatment of squamous cell carcinoma (SCC) of the head and neck has been largely ineffective because of tumor cell resistance. This study examined combinations of cisplatin, 4' demethylepipodophyllotoxin ethylidene D-glucoside (VP-16), and ciprofloxacin, a quinolone antibiotic. VP-16 and ciprofloxacin were used in an effort to inhibit DNA repair and increase cytotoxicity. Chemotherapeutic agents often have a direct damaging effect on cellular DNA. Cytotoxicity may be the result of incomplete DNA repair mechanisms; whereas tumor cell resistance to drugs may be due to efficient DNA recovery. A nuclear enzyme especially important to DNA repair and cell growth is topoisomerase II (topo II). Targeted inhibition of topo II by VP-16 and ciprofloxacin may cause increased cisplatin cytotoxicity. SCC cell lines of head and neck origin were treated with a combination of cisplatin, VP-16, and/or ciprofloxacin with cell viability being assessed by the MTT colorimetric assay. Four of five SCC lines examined demonstrated significant augmentation of cisplatin cytotoxicity with the addition of both VP-16 and ciprofloxacin. These in vitro data suggest methods may exist for improving the chemotherapeutic treatment of SCC of the head and neck.

Two-colour immunoenzymatic technique using sequential staining by APAAP to evaluate two cell antigens

AIMS

To extend the alkaline phosphatase-antialkaline phosphatase (APAAP) immunoenzyme single stain method to a more generally applicable double stain technique. This will allow two primary antibodies of the same isotype of IgG and specifically the nuclear antigen bromodeoxyuridine (BRdU) to be evaluated with a cell surface antigen identifier.

METHOD

Sequential applications of the APAAP method showed two antigen sites by different dye couplings to a common alkaline phosphatase substrate, producing blue and red reaction products on the same slide. Antigens on different cell populations as well as those in different compartments of the same cell were analysed. The method allowed a surface antigen monoclonal to be revealed first, using an optimal fixative, before alcohol/gluteraldehyde fixation was used to start the second (BRdU) staining sequence.

RESULTS

An analysis of double staining of T lymphocyte subsets (CD4 and CD8) showed no significant difference in the order of application of the primaries (n = 10) and no significant difference from their corresponding single stain results (n = 50), confirming the validity of the technique where antigens are exclusively distributed. Other examples, including antigens distributed in different compartments of the same cell, displayed discrete staining which implied validity.

CONCLUSION

Double staining by APAAP with this technique seems to be applicable to those cases where antigens are exclusively distributed and includes cases where different compartments of the same cell are stained. It is especially useful in revealing antigens that require different fixation and preparation--that is DNA incorporated BRdU with a surface antigen. But it does seem to have a limited ability to produce a dual colour at a common site.

Pitfalls in the determination of absolute dimensions using angiographic catheters as calibration devices in quantitative angiography

Using catheter outer diameter as a scaling device, quantitative coronary arteriography allows the precise and objective measurement of change in absolute dimensions of coronary arteries after mechanical or pharmacologic intervention. Because of variable density in the wall of the catheter, automated systems might vary in the determination of the outer catheter diameter. To examine this premise, catheters in a variety of French sizes from 6 manufacturers were injected with radiographic contrast and used as scaling devices for arterial phantoms of known geometric dimension. Radiographic diameters of the catheters were determined by applying the quantitative coronary arteriographic algorithm to the catheters using a calibration grid in the same field of view. The varying composition of the catheters resulted in differing x-ray attenuation and, subsequently, automated edge-detection algorithms varied widely in determining the actual catheter diameter to be used as a scaling factor. For instance, a Lucite "artery" with a minimal luminal diameter of 1.50 mm (image calibrated using the micrometer-determined outside diameter of a Baxter 8Fr guiding catheter) resulted in a quantitative angiographic diameter of 2.03 mm (overestimation by 35%). If the diameter of a similar size Shiley catheter was used to calibrate the image, a luminal diameter of 1.60 mm was determined: a difference of 0.43 mm based solely on differences in scaling catheter attenuation. These data suggest that a specific "fingerprint" for each catheter material and catheter French size exists, rendering generalizations about catheter size questionable. These observations are important for quantitative angiography where many brands and sizes of angiographic catheters are being used clinically.(ABSTRACT TRUNCATED AT 250 WORDS)

A new class of electrodes of 'intermediate invasiveness': preliminary experience with epidural pegs and foramen ovale electrodes in the mapping of seizure foci

Non-invasive electroencephalographic (EEG) recording with scalp and sphenoidal leads is often insensitive to precise localization of ictal onset, and can be distorted by skull defects and underlying lesions or deformities of the brain. We present preliminary experience with epidural pegs and foramen ovale electrodes used in 30 cases of intractable partial epilepsy where non-invasive EEG did not define a zone of epileptogenesis with sufficient precision to recommend resection, or to dictate precise placement of depth electrodes or subdural girds. Custom designed mushroom shaped peg electrodes were implanted via 4.5 mm twist-drill skull holes for epidural recording from cortical areas of suspected epileptogenesis. Foramen ovale electrodes (flexible 3-contact leads) were introduced via percutaneous puncture of Meckel's cave cistern for recording from mesiotemporal regions. Chronic recording was performed for 4 to 26 days (mean 9.2 days). There were no serious complications and signal quality was excellent in every electrode. Based on interictal and ictal records, resective surgery was performed in 8 cases, more focused further invasive recording was recommended in 15 cases (with subsequent resective surgery), and surgical options were excluded in 7 cases. It is concluded that these electrodes of 'intermediate invasiveness' represent a safe and effective tool in the armamentarium for mapping complicated or elusive epileptic foci. They can be used in lieu of, in addition to, or prior to more invasive measures. Their greatest advantage lies in their relative safety and ability to survey extensive zones of suspected epileptogenesis so as to guide and focus further mapping and surgical intervention.

The omega subunit of Escherichia coli K-12 RNA polymerase is not required for stringent RNA control in vivo

Igarashi et al. (K. Igarashi, N. Fujita, and A. Ishihama, Nucleic Acids Res. 17:8755-8765, 1989) reported that the omega (omega) subunit of Escherichia coli RNA polymerase was required for stringent control as judged by in vitro transcription assays in the presence and absence of guanosine 3',5'-bispyrophosphate (ppGpp). This conclusion predicts that a deletion of the omega gene (designated rpoZ or spoS) should show a relaxed RNA control phenotype in vivo. However, we find that wild-type stringent control of stable RNA accumulation is unaffected by a spoS null allele that abolishes cellular production of the omega protein. We conclude that omega protein is not necessary for the operation of the stringent RNA control response.