Clarithromycin with low dose dexamethasone and thalidomide is effective therapy in relapsed/refractory myeloma.

A combination of clarithromycin, low dose of thalidomide and low dose dexamethasone was used in a phase II study to treat patients with relapsed and refractory myeloma. Thirty patients received clarithromycin 250 mg twice daily and thalidomide 50 mg at night on an ongoing basis with 4-d pulses of 10 mg dexamethasone given monthly. Eight patients had permitted escalation of thalidomide dosage up to 200 mg daily. The combination was well tolerated and could be given to elderly, infirm and severely cytopenic patients. Response rates were high, with 89% achieving at least 50% reduction in paraprotein and a 96% overall response rate. Although clarithromycin has only minimal anti-myeloma properties when used as a single agent, its combination with thalidomide and dexamethasone appears very effective, allowing these to be used in lower and more tolerable doses with good clinical effects.

Histiocytic lymphoma presenting as a testicular tumour and terminating in acute monoblastic leukaemia.

A 58 year old man presented in 1995 with a swollen testicle. After orchidectomy, a diagnosis of poorly differentiated lymphoma was made. Lymphoid, epithelial, and seminoma markers were all negative. Six months later he developed a buccal lesion, which was biopsied and reported as a high grade non-Hodgkin's lymphoma. It responded completely to chemotherapy but within a year he developed a forearm swelling, which was biopsied and imprints made before fixation of the material. Immunocytochemistry on the imprints showed positivity with antibodies to CD4, CD68, and muramidase, and the non-specific esterase cytochemical stain was strongly positive, leading to a diagnosis of true histiocytic lymphoma. Despite further treatment, the patient entered a terminal acute leukaemic phase, the blasts marking as monoblasts. Review of all the biopsies, including molecular investigations and further immunohistochemistry studies performed retrospectively on the original biopsy, demonstrated that this was the same malignant cell line throughout, and we conclude that this is a case of histiocytic lymphoma, initially presenting as a testicular tumour and terminating in acute monoblastic leukaemia. A diagnosis of histiocytic lymphoma should be considered when lymphoid markers are negative in an apparent lymphoma, but should not be made without recourse to appropriate immunophenotypic and molecular studies.

Centrosome maturation.

In the past, centrosome maturation has been described as the change in microtubule nucleation potential that occurs as cells pass through specific phases of the cell cycle. It is suggested that the idea of centrosome maturation be expanded to include gain of functions that are not necessarily related to microtubule nucleation. Some of these functions could be transient and dependent on the temporary association of molecules with the centrosome as cells progress through the cell cycle. Thus, the centrosome may best be viewed as a site for mediating macromolecular interactions, perhaps as a central processing station within the cell. The centromatrix, a relatively stable lattice of polymers within the centrosome's PCM, could serve as a scaffold for the transient binding of mediator molecules, as well as allow the dynamic exchange of centrosome constituents with a soluble cytoplasmic pool. New evidence adds support to the idea that centrioles are crucial for the maintenance of PCM structure. However, significant evidence indicates that aspects of centrosome structure and function can be maintained in the absence of centrioles. In the case of paternal centrosome maturation, sperm centrioles may not contain an associated centromatrix. It is proposed that regulation of paternal centrioles or centriole associated proteins could mediate centriole-dependent centromatrix assembly following fertilization. Thus, regulation of centromatrix-centriole interactions could be involved in maintaining the integrity of the centrosome's PCM and play an important role in centrosome disassembly during cell differentiation and morphogenesis.

Respiratory failure during induction chemotherapy for acute myelomonocytic leukaemia (FAB M4Eo) with ara-C and all-trans retinoic acid.

We report two cases of acute myeloid leukaemia FAB classification M4Eo with high white cell counts at presentation, who developed acute respiratory failure with pulmonary infiltrates on chest radiograph soon after commencing conventional cytotoxic chemotherapy plus all-trans retinoic acid (ATRA). We suggest that in patients with M4Eo ATRA should be used with caution, perhaps delaying its commencement until the white cell count is < 10 x 109/l.

Reconstitution of microtubule nucleation potential in centrosomes isolated from Spisula solidissima oocytes.

Treatment of isolated Spisula solidissima centrosomes with KI removes (gamma)-tubulin, 25 nm rings, and their microtubule nucleation potential, revealing the presence of a filamentous lattice, the 'centromatrix'. Treatment of this centromatrix with Spisula oocyte extract results in the binding of (gamma)-tubulin and 25 nm rings, and the recovery of microtubule nucleation potential. Fractionation of this extract resulted in the separation of elements that are required for the recovery of microtubule nucleation potential. We show that some, but not all, of the elements needed cosediment with microtubules. Further, extracts prepared from activated (meiotic) and non-activated (interphase) Spisula oocytes, CHO cells blocked in S phase, Drosophila embryos and Xenopus oocytes all support the recovery of microtubule nucleation potential by the Spisula centromatrix. These results demonstrate that components necessary for centrosome-dependent microtubule nucleation are functionally conserved and abundant in both interphase and meiotic/mitotic cytoplasm.

Familiality of monocyte esterase deficiency in patients on continuous ambulatory peritoneal dialysis.

The purpose of this study was to determine whether or not peripheral blood monocyte esterase deficiency occurring in patients on CAPD was a familial characteristic. The peripheral blood monocyte esterase status of 74 patients on CAPD was determined by a naphthyl acetate esterase staining of cytospin preparations of their mononuclear cells following separation over ficoll. The peripheral blood of first degree relatives and spouses of monocyte esterase deficiency patients was similarly investigated for the deficiency. Three patients bad monocyte esterase deficiency and familiality of the defect was demonstrated in two of their families. The third family was incompletely investigated because of lack of consent. The monocyte esterase deficiency demonstrated in this cohort of patients did not result from their renal failure but was a familial characteristic.

Menorrhagia in von Willebrand disease successfully treated with single daily dose tranexamic acid.

Four cases of menorrhagia in von Willebrand disease were successfully treated with tranexamic acid given in a single daily dose of 4 g for the first 3-5 days of the menstrual cycle. The pathophysiology and pharmacokinetics are discussed. The apparent improved efficacy and acceptability of this new dosing regime have been highlighted.

Renal failure and esterase-negative monocytes.

Monocyte esterase deficiency (MED) has been found to be linked with autoimmune (1,2) and lymphoproliferative (2,3) disease. The incidence of MED where > 85% of peripheral blood monocytes are consistently negative in the cytochemical stain for monocyte esterase activity, was shown to be significantly raised in patients with renal failure (3.8%) as compared to the incidence in normal blood donors (0.8%) in a survey performed at the Belfast City Hospital in 1987 (2). The overall occurrence of any proportion of esterase-negative monocytes (ENMs) in patients with renal disease has not been previously studied. The aims of this study were to document this occurrence, and by examining the clinical and biochemical parameters associated with ENMs to identify possible reasons for their occurrence. The original survey data were reexamined and further information previously unreported regarding the occurrence of ENMs was extracted from the renal patient cohort data. Clinical and biochemical data were obtained from the hospital notes of the renal patients and associations sought between these parameters and the occurrence of ENMs. ENMs occurred in a significantly higher proportion (31%) of the renal patients than in the normal population (8%; p < 0.001 chi-sq.) or any other hospital population. A highly significant association between rising serum phosphate levels and increasing proportions of ENMs was identified (p < .001) and this association proved to be independent of serum creatinine levels and renal dialysis status. There is a marked increase in occurrence of esterase-negative monocytes in patients with renal failure. This increase was not caused by the degree of renal failure as reflected by serum creatinine levels, nor by renal transplantation or immunosuppressive therapy. A significant association between rising serum phosphate and increasing proportion of esterase-negative monocytes was identified. This new information, when considered with the previously described experimental and epidemiology evidence for malfunction of esterase negative monocytes, identifies a phenomenon which may contribute to the immunological difficulties of patients with chronic renal failure.

Antineutrophil cytoplasmic antibodies in myelodysplasia.

Antibodies to neutrophil cytoplasmic antigens (ANCA) are good serological markers for patients with mainly vasculitic conditions. Two main types of ANCAs have been detected, the first termed cytoplasmic antineutrophil cytoplasmic antibody (cANCA) are mainly associated with patients with Wegener's granulomatosis, the other termed perinuclear antineutrophil cytoplasmic antibody (pANCA) are mainly associated with patients with renal vasculitis, rheumatic and collagen disorders. These antibodies are against various constituents of neutrophil granules. In patients with myelodysplasia, defects in normal granulocyte development are seen. We report a series of twelve patients with myelodysplasia of whom at least four showed a low titre and one a high titre of pANCA. Two of these patients also had demonstrable activity against myeloperoxidase (MPO). None of these patients had any evidence of systemic or cutaneous vasculitis or of any autoimmune disorder. There was no pANCA positivity in an age matched control group.

The rate of removal of pyrimidine dimers in quiescent cultures of normal human and xeroderma pigmentosum cells.

The rate of removal of pyrimidine dimers from DNA of UV (254 nm)-irradiated (1 J/m2) normal and xeroderma pigmentosum (XP) cells maintained in culture as nondividing populations was determined. Several normal and XP strains from complementation groups A, C and D were studied. The excision rates and survival ability of nondividing cells were examined to determine if an abnormal sensitivity was associated with a decreased rate of dimer excision. The results show that all normal strains studied excise pyrimidine dimers at the same rate, with the rate curve characterized by two components. All 'excision-deficient' XP strains excise dimers at a slower-than-normal rate, with the rate curves also characterized by two components. The rate constants for the first components of all of the XP strains (group A, C and D) are the same, one tenth of the normal rate constant, except for XP8LO (group A). XP8LO has a first-component rate constant similar to that of normal strains and a second component rate constant similar to that of other group A strains (XP12BE, XP25RO). Thus, the slower rate of dimer excision in XP8LO is due to a defect in the mechanism responsible for the second component of the excision-rate curve. In general, an abnormal sensitivity of nondividing cells to UV is associated with a reduced dimer-excision rate. A notable exception to this is the group C strain XP1BE which has an initial repair rate similar to that of group A XP12BE but is considerably more resistant when survival is measured.

Evidence that DNA excision-repair in xeroderma pigmentosum group A is limited but biologically significant.

The loss of pyrimidine dimers in nondividing populations of an excision-repair deficient xeroderma pigmentosum group A strain (XP12BE) was measured throughout long periods (up to 5 months) following exposure to low doses of ultraviolet light (UV, 254 nm) using a UV endonuclease-alkaline sedimentation assay. Excision of about 90% of the dimers induced by 1 J/m2 occurred during the first 50 days. The rate curve has some similarities with that of normal excision-repair proficient cultures that may not be coincidental. Rate curves for both XP12BE and normal cultures are characterized by a fast and slow component, with both rate constants for the XP12BE cultures (0.15 day-1 and 0.025 day-1) a factor of 10 smaller than those observed for the respective components of normal cell cultures. The slow components for both XP12BE and normal cultures extrapolate to about 30% of the initial number of dimers. No further excision was detected throughout an additional 90-day period even though the cultures were capable of excision-repair of other newly-introduced pyrimidine dimers. We conclude that nondividing XP12BE cells in addition to having a slower repair rate, cannot repair some of the UV-induced DNA damage. The repair in XP12BE is shown to have biological significance as detected by a cell-survival assay and dose-fractionation techniques. Nondividing XP12BE cells are more resistant to UV when irradiated chronically than when irradiated acutely with the same total dose.

Repair of radiation-induced DNA damage in nondividing populations of human diploid fibroblasts.

The occurrence of DNA repair in UV- (254 nm) and X-irradiated normal human diploid fibroblasts maintained in a quiescent, nondividing state using low serum (0.5%) medium was ascertained. Techniques that detect different steps of the excision repair process were used so that the extent of completion of repair at single sites could be determined. These included measuring the disappearance of pyrimidine dimers by chromatography, detecting repair synthesis by density-gradient and autoradiographic methods and detecting the rejoining of repaired regions and repair of x-ray-induced single-strand DNA breaks using alkaline sucrose gradients. Results show that dimer excision occurs and the subsequent steps of repair synthesis and ligation are completed. About 50% of the dimers formed by exposure to 20 J/m2 is excised in the initial 24-h post-UV period. DNA repair (unscheduled DNA synthesis) can be detected through a 5-d post-UV period. The fraction of damaged sites eventually repaired is not known. X-ray-induced single-strand DNA breaks are repaired rapidly.

An effect of ultraviolet light on RNA and protein synthesis in nondividing human diploid fibroblasts.

Nondividing human diploid fibroblasts maintained in medium containing 0.5% calf serum do not survive when exposed to low doses of UV (254 nm). The extent of killing is dose and strain dependent. DNA excision repair-proficient cells are more resistant than excision repair-deficient cells. Results of measurements of the effect of UV on RNA and protein synthesis in repair-proficient and -deficient (XP12BE) cells are reported. UV causes an immediate and equal depression of the RNA synthesis rate in both kinds of cells. A recovery to control rates was observed only at low (5 J/m2) doses in repair-deficient cells and at higher doses (20 J/m2) in repair-proficient cells. No recovery was observed at doses that cause substantial reductions in survival (greater than 5 J/m2 for XP12BE; greater than 40 J/m2 for repair-proficient populations). No initial effect on rate of protein synthesis was detected at doses less than 20 J/m2. However, in XP12BE populations, a decreased rate first evident at 15-30 h post-UV and before any cell degeneration and loss was observed for doses as low at 7 J/m2. This delayed effect was not observed in repair-proficient populations. The results are consistent with the hypothesis that the lethal action of UV in nondividing cells is one on DNA that leads to an inhibition of required protein synthesis by preventing RNA transcription.

A study of the effect of ultraviolet light on the division potential of human diploid fibroblasts.

Culture and UV (254 nm) irradiation conditions that are suggested as appropriate for a study of the effect of UV on the limited in vitro lifespan of a normal human diploid fibroblast (HDF) strain are first described. An inoculation density at each subcultivation of 1.8 x 10(4) viable cells/cm-2 permits the decline in proliferative capacity to occur with kinetics similar to that observed using a 1:2 split and prevents cell overlap at the time of irradiation. Doses of 5 and 10 J/m2 have only a slight effect on initial growth rates and little or no effect on cell density achieved at confluence. With these conditions populations can be irradiated several times throughout the in vitro lifespan. No effect of UV on the limited division potential was observed. In the extreme, a population irradiated 14 times, once every second passage starting at P-18 with doses of 5 or 10 J/m2 had the same lifespan as controls, as measured by lifespan determinations and thymidine labeling index. Transformed cells were not detected in the multi-irradiated populations. Evidently no accumulation in the populations of damage induced by UV that affected life span, thymidine labeling index, growth rates or confluent cell densities occurred. No selection of a population with altered sensitivity occurred. An argument that genome hits may not be a prime reason for the limited proliferative capacity of HDF populations is presented.