Adsorption interaction of carrier-free thallium species with gold and quartz surfaces

The adsorption interactions of thallium and its compounds with gold and quartz surfaces were investigated. Carrier-free amounts of thallium were produced in nuclear fusion reactions of alpha particles with thick gold targets. The method chosen for the studies was gas thermochromatography and varying the redox potential of the carrier gases. It was observed that thallium is extremely sensitive to trace amounts of oxygen and water, and can even be oxidized by the hydroxyl groups located on the quartz surface. The experiments on a quartz surface with O2, He, H2 gas in addition with water revealed the formation and deposition of only one thallium species – TlOH. The adsorption enthalpy was determined to be Δ H SiO2 ads(TlOH) = −134 ± 5 kJ mol−1. A series of experiments using gold as stationary surface and different carrier gases resulted in the detection of two thallium species – metallic Tl (H2 as carrier gas) and TlOH (O2, O2+H2O and H2+H2O as pure carrier gas or carrier gas mixture) with Δ H Au ads(Tl) = −270 ± 10 kJ mol− and Δ H Au ads(TlOH) = −146 ± 3 kJ mol−1. These data demonstrate a weak interaction of TlOH with both quartz and gold surfaces. The data represent important information for the design of future experiments with the heavier homologue of Tl in group 13 of the periodic table – element 113 (E113).

Adsorption interaction of astatine species with quartz and gold surfaces

The adsorption interaction of various astatine species with quartz and gold surfaces was investigated by gas chromatography methods. Due to variations of the redox potential of the carrier gas elemental astatine, astatine oxide and hypo-astatic acid have been produced. The identification of the astatine compounds is based on the analogy assumption to the gas phase chemistry of the closest homologues in group 17 of the periodic table, iodine and bromine. The deposition temperatures as well as enthalpies of adsorption have been determined for the astatine species. The enhancement of the metallic character within group 17 towards higher Z is clearly confirmed. Macroscopic properties (sublimation enthalpy) of previously unstudied AtO2 and HAtO were estimated. The determined data for elemental astatine were compared to available literature data. Based on the obtained experimental results possible designs of experiments for studying of chemical properties of the recently discovered element 117 can be suggested.

The thermal release of scandium from titanium metal – a simple way to produce pure 44Sc for PET application

The radionuclide-generator based access to radiopharmaceutical isotopes represents a valuable alternative to directly produced isotopes at particle accelerators or nuclear reactors. The 44Ti based generator is of increasing interest for the delivery of PET-radiopharmaceutical isotopes used for imaging. The product of this generator 44Sc represents with its 3.97 h half-life and 94.3% positron branching [1] a very promising candidate for labeling PET radiopharmaceuticals. The long half-life of 58.9±0.3 y [2] of the 44Ti assures a constant and long lasting production of the daughter nuclide.

Here we present a gas phase separation method of scandium from titanium via thermal release in vacuum. Titanium foils were irradiated with 40Ar to produce scandium in multi-nucleon transfer reactions. Another production reaction used was the irradiation of titanium by neutrons from the SINQ neutron source at the Paul Scherrer Institute (PSI).

The titanium metal foils containing 44mSc and 46Sc were heated up for time periods of 15 and 60 min to temperatures between 900 °C and 1500 °C in vacuum. Thus, release properties of scandium from titanium under these conditions were studied. The released scandium was collected on tantalum foils and could be rinsed of with concentrated nitric acid resulting in carrier free scandium nitrate solutions. From the experimental results optimum release conditions are suggested.

Gas chromatography of indium in macroscopic and carrier-free amounts using quartz and gold as stationary phases

The chemical investigation of E113 is likely to become soon feasible. The determination of chemical properties of carrier-free amounts of the lighter homologues of element 113, especially indium and thallium, allows designing experimental set-ups and selecting experimental conditions suitable for performing these studies. Here, we present investigations of the interaction of indium species with quartz and gold surfaces. Deposition temperatures as well as enthalpies of adsorption were determined for indium T dep=739±20 °C (−ΔH ads(In)=227±10 kJ mol−1) and for indium hydroxide T dep=250±20 °C (−ΔH ads(InOH)= 124±10 kJ mol−1) respectively, on quartz. In case of adsorption of indium on a gold surface only a lower limit of the deposition temperature was established T dep>980 °C (−ΔH ads(In)≥315±10 kJ mol−1). Investigations of macroscopic amounts of indium in thermosublimation experiments at similar experimental conditions were instrumental to establish a tentative speciation of the observed indium species.

Thermochromatographic studies of mercury and radon on transition metal surfaces

In preparation for the experimental investigation of chemical properties of element 112 model studies were conducted based on the assumed similarity of element 112 to either the noble gas Rn or the transition metal Hg, its supposed lighter homologue in group 12. The adsorption behavior of elemental Hg on the transition metals Ag, Au, Ni, Pd, and Pt were investigated experimentally by off-line gas thermochromatography. The deduced adsorption data of Hg were compared with new values calculated using the Eichler–Miedema model. The observed sequence of increasing Hg-metal-interactions for Ag < Ni < Au < Pd < Pt confirms the predicted trend. The only exception was Pd, on which Hg was calculated to adsorb at a higher temperature than on Pt. Difficulties to obtain reproducible clean surfaces of Ag, Ni, Pd, and Pt led to the choice of Au as the best metal surface suitable to adsorb Hg.

For fast on-line gas thermochromatography studies on metallic surfaces a new set-up was developed based on the In-situ Volatilization and On-line detection technique (IVO). This set-up was tested in on-line thermochromatographic investigations with short-lived Hg isotopes and 219Rn, using Au or Pd as stationary surfaces. An overall efficiency of about 60% and a transportation time less than 25 s was determined for this newly designed IVO. A separation factor of more than 106 was estimated for non-volatile species.

Attempts to chemically investigate element 112

Two experiments aiming at the chemical investigation of element 112 produced in the heavy ion induced nuclear fusion reaction of 48Ca with 238U were performed at the Gesellschaft für Schwerionenforschung (GSI), Darmstadt, Germany. Both experiments were designed to determine the adsorption enthalpy of element 112 on a gold surface using a thermochromatography setup. The temperature range covered in the thermochromatography experiments allowed the adsorption of Hg at about 35 °C and of Rn at about -180 °C. Reports from the Flerov Laboratory for Nuclear Reactions (FLNR), Dubna, Russia claim production of a 5-min spontaneous fission (SF) activity assigned to 283112 for the 238U(48Ca,3n) 283112 reaction. Hence, Experiment I was designed to detect spontaneously fissioning (SF) isotopes of element 112 with half-lives (t 1/2) longer than about 20 s. 11 high-energy events were detected. 7 events exhibit a deposition pattern resembling a chromatographic peak in the vicinity of Rn deposition. However, the energy of the events observed in Experiment I was lower than expected for a SF-decay of 283112. Therefore, these events could not be unambiguously attributed to the decay of 283112. In contradiction with earlier publications newer reports from FLNR Dubna claim that 283112 decays by α-particle emission (E α = 9.5 MeV) with t 1/2 = 4 s followed by a SF-decay of 279Ds (t 1/2 = 0.2 s). Therefore, Experiment II was designed to be sensitive to both claimed decay properties of 283112. However, during this experiment neither short α-SF correlations nor SF coincidences were detected. The conclusion is that 283112 was not unambiguously detected, neither in Experiment I nor in Experiment II.

Gas phase chemistry of technetium and rhenium oxychlorides

The chloride and oxychloride chemistry of the group 7 elements Tc and Re was investigated in order to develop an experimental approach to a gas chemical characterisation of bohrium (Bh, element 107). In thermochromatography experiments with trace amounts of101,104Tc and183,184Re the formation of one volatile compound was observed in O2/HCl containing carrier gas, which was attributed to MO3Cl (M = Tc, Re). From the measured deposition temperatures the adsorption enthalpies on quartz surfaces ΔHads(TcO3Cl) = -51 ± 3 kJ/mol and ΔHads(ReO3Cl) = -62 ± 3 kJ/mol were evaluated. The sublimation enthalpies were derived using an empirical correlation between Δ Hadsand ΔHsubl: ΔHsubl(TcO3Cl) = 49±10 kJ/mol and ΔHsubl(ReO3Cl) = 67±10 kJ/mol. A fast gas chemical separation technique for highly volatile compounds of short-lived isotopes based on isothermal gas solid adsorption chromatography (OLGA-principle) was developed. With a modified OLGA device, model studies with the short-lived nuclides106,107,108Tc and169,170,174,176Re were carried out in preparation of an experimental gas chemical investigation of bohrium (Bh, element 107). Separation times of less than 3 s were achieved. A good separation of the oxychlorides of group 7 elements from chloride and oxychloride compounds of152-155Er,151-154Ho (as models for actinide elements),98-101Nb,99-102Zr (as models for light transactinide elements),218Po, and214Bi was accomplished in this chemical system.

Redimune NF Liquid, a ready-to-use, high-concentration intravenous immunoglobulin therapy preparation, is safe and typically well tolerated in the routine clinical management of a broad range of conditions

In clinical practice, intravenous immunoglobulin therapy (IVIG) is used in the management of a wide variety of medical conditions. Observational studies examining IVIG use in routine clinical practice are therefore an important means of validating findings from more strictly randomized controlled trials of patients with specific conditions. In this observational study, we examined the tolerability of a high-concentration (12%) ready-to-use liquid IVIG (Redimune NF Liquid) when used in the standard management of a diverse range of conditions (including primary immunodeficiency diseases, neurology conditions, oncology conditions and immune thrombocytopaenic purpura). IVIG regimen and dose were selected by the physician based on the summary of product characteristics. During the study, 193 infusions were administered to 51 patients in 153 infusion cycles (per infusion cycle: one to five infusions; mean dose, 347.6 mg/kg; mean duration, 202.4 min). The mean maximum infusion rate per cycle was 2.9 mg/kg/min, demonstrating that the infusion rate was often higher than that recommended in the summary of product characteristics. Redimune NF Liquid was well tolerated: there were 36 adverse reactions (at least probably associated with IVIG) in 10 patients (19.6% of sample, 0.24 per infusion cycle, 0.19 per infusion). The most common adverse reaction was headache (50% of reactions), followed by chills (13.8%). Most reactions (69%) were mild and there were no serious or unexpected reactions. In conclusion, in routine clinical practice involving patients with many different conditions, Redimune NF Liquid was well tolerated by the majority of patients.

MAPK-ERK activation in kidney of male rats chronically fed ochratoxin A at a dose causing a significant incidence of renal carcinoma

Kidney samples of male Fischer 344 (F-344) rats fed a carcinogenic dose of OTA over 7 days, 21 days and 12 months were analysed for various cell signalling proteins known to be potentially involved in chemical carcinogenicity. OTA was found to increase the phosphorylation of atypical-PKC. This was correlated with a selective downstream activation of the MAP-kinase extracellular regulated kinases isoforms 1 and 2 (ERK1/2) and of their substrates ELK1/2 and p90RSK. Moreover, analysis of effectors acting upstream of PKC indicated a possible mobilisation of the insulin-like growth factor-1 receptor (lGFr) and phosphoinositide-dependent kinase-1 (PDK1) system. An increased histone deacetylase (HDAC) enzymatic activity associated with enhanced HDAC3 protein expression was also observed. These findings are potentially relevant with respect to the understanding of OTA nephrocarcinogenicity. HDAC-induced gene silencing has previously been shown to play a role in tumour development. Furthermore, PKC and the MEK-ERK MAP-kinase pathways are known to play important roles in cell proliferation, cell survival, anti-apoptotic activity and renal cancer development.

Chemical characterization of element 112

The heaviest elements to have been chemically characterized are seaborgium (element 106), bohrium (element 107) and hassium (element 108). All three behave according to their respective positions in groups 6, 7 and 8 of the periodic table, which arranges elements according to their outermost electrons and hence their chemical properties. However, the chemical characterization results are not trivial: relativistic effects on the electronic structure of the heaviest elements can strongly influence chemical properties. The next heavy element targeted for chemical characterization is element 112; its closed-shell electronic structure with a filled outer s orbital suggests that it may be particularly susceptible to strong deviations from the chemical property trends expected within group 12. Indeed, first experiments concluded that element 112 does not behave like its lighter homologue mercury. However, the production and identification methods used cast doubt on the validity of this result. Here we report a more reliable chemical characterization of element 112, involving the production of two atoms of (283)112 through the alpha decay of the short-lived (287)114 (which itself forms in the nuclear fusion reaction of 48Ca with 242Pu) and the adsorption of the two atoms on a gold surface. By directly comparing the adsorption characteristics of (283)112 to that of mercury and the noble gas radon, we find that element 112 is very volatile and, unlike radon, reveals a metallic interaction with the gold surface. These adsorption characteristics establish element 112 as a typical element of group 12, and its successful production unambiguously establishes the approach to the island of stability of superheavy elements through 48Ca-induced nuclear fusion reactions with actinides.

A Toxicogenomics Approach to Identify New Plausible Epigenetic Mechanisms of Ochratoxin A Carcinogenicity in Rat

Ochratoxin A (OTA) is a mycotoxin occurring naturally in a wide range of food commodities. In animals, it has been shown to cause a variety of adverse effects, nephrocarcinogenicity being the most prominent. Because of its high toxic potency and the continuous exposure of the human population, OTA has raised public health concerns. There is significant debate on how to use the rat carcinogenicity data to assess the potential risk to humans. In this context, the question of the mechanism of action of OTA appears of key importance and was studied through the application of a toxicogenomics approach. Male Fischer rats were fed OTA for up to 2 years. Renal tumors were discovered during the last 6 months of the study. The total tumor incidence reached 25% at the end of the study. Gene expression profile was analyzed in groups of animals taken in intervals from 7 days to 12 months. Tissue-specific responses were observed in kidney versus liver. For selected genes, microarray data were confirmed at both mRNA and protein levels. In kidney, several genes known as markers of kidney injury and cell regeneration were significantly modulated by OTA. The expression of genes known to be involved in DNA synthesis and repair, or genes induced as a result of DNA damage, was only marginally modulated. Very little or no effect was found amongst genes associated with apoptosis. Alterations of gene expression indicating effects on calcium homeostasis and a disruption of pathways regulated by the transcription factors hepatocyte nuclear factor 4 alpha (HNF4alpha) and nuclear factor-erythroid 2-related factor 2 (Nrf2) were observed in the kidney but not in the liver. Previous data have suggested that a reduction in HNF4alpha may be associated with nephrocarcinogenicity. Many Nrf2-regulated genes are involved in chemical detoxication and antioxidant defense. The depletion of these genes is likely to impair the defense potential of the cells, resulting in chronic elevation of oxidative stress in the kidney. The inhibition of defense mechanism appears as a highly plausible new mechanism, which could contribute to OTA carcinogenicity.

Treatment of hairy cell leukemia with cladribine (2-chlorodeoxyadenosine) by subcutaneous bolus injection: a phase II study

BACKGROUND

To assess the activity and toxicity of 2-chlorodeoxyadenosine (cladribine, CDA) given by subcutaneous bolus injections to patients with hairy cell leukemia (HCL).

PATIENTS AND METHODS

Sixty-two eligible patients with classic or prolymphocytic HCL (33 non-pretreated patients, 15 patients with relapse after previous treatment, and 14 patients with progressive disease during a treatment other than CDA) were treated with CDA 0.14 mg/kg/day by subcutaneous bolus injections for five consecutive days. Response status was repeatedly assessed according to the Consensus Resolution criteria.

RESULTS

Complete and partial remissions were seen in 47 (76%) and 13 (21%) patients, respectively, for a response rate of 97%. All responses were achieved with a single treatment course. Most responses occurred early (i.e. within 10 weeks) after start of CDA therapy, but response quality improved during weeks and even months after treatment completion. The median time to treatment failure for all patients was 38 months. Leukopenia was the main toxicity. Granulocyte nadir (median 0.2 x 10(9)/l) was strongly associated with the incidence of infections (P = 0.0013). Non-specific lymphopenia occurred early after CDA treatment, and normal lymphocytes recovered slowly over several months. No significant associations were found between infections and nadir count of lymphocytes or any lymphocyte subpopulation. No opportunistic infections were observed.

CONCLUSIONS

One course of CDA given by subcutaneous bolus injections is very effective in HCL. The subcutaneous administration is more convenient for patients and care providers, and has a similar toxicity profile to continuous intravenous infusion. The subcutaneous administration of CDA is a substantial improvement and should be offered to every patient with HCL requiring treatment with CDA.

Chemical investigation of hassium (element 108)

The periodic table provides a classification of the chemical properties of the elements. But for the heaviest elements, the transactinides, this role of the periodic table reaches its limits because increasingly strong relativistic effects on the valence electron shells can induce deviations from known trends in chemical properties. In the case of the first two transactinides, elements 104 and 105, relativistic effects do indeed influence their chemical properties, whereas elements 106 and 107 both behave as expected from their position within the periodic table. Here we report the chemical separation and characterization of only seven detected atoms of element 108 (hassium, Hs), which were generated as isotopes (269)Hs (refs 8, 9) and (270)Hs (ref. 10) in the fusion reaction between (26)Mg and (248)Cm. The hassium atoms are immediately oxidized to a highly volatile oxide, presumably HsO(4), for which we determine an enthalpy of adsorption on our detector surface that is comparable to the adsorption enthalpy determined under identical conditions for the osmium oxide OsO(4). These results provide evidence that the chemical properties of hassium and its lighter homologue osmium are similar, thus confirming that hassium exhibits properties as expected from its position in group 8 of the periodic table.

In vivo local determination of tissue optical properties: applications to human brain

Local and superficial near-infrared (NIR) optical-property characterization of turbid biological tissues can be achieved by measurement of spatially resolved diffuse reflectance at small source-detector separations (<1.4 mm). However, in these conditions the inverse problem, i.e., calculation of localized absorption and the reduced scattering coefficients, is necessarily sensitive to the scattering phase function. This effect can be minimized if a new parameter of the phase function gamma, which depends on the first and the second moments of the phase function, is known. If gamma is unknown, an estimation of this parameter can be obtained by the measurement, but the uncertainty of the absorption coefficient is increased. A spatially resolved reflectance probe employing multiple detector fibers (0.3-1.4 mm from the source) is described. Monte Carlo simulations are used to determine gamma, the reduced scattering and absorption coefficients from reflectance data. Probe performance is assessed by measurements on phantoms, the optical properties of which were measured by other techniques [frequency domain photon migration (FDPM) and spatially resolved transmittance]. Our results show that changes in the absorption coefficient, the reduced scattering coefficient, and gamma can be measured to within +/-0.005 mm(-1), +/-0.05 mm(-1), and +/-0.2, respectively. In vivo measurements performed intraoperatively on a human skull and brain are reported for four NIR wavelengths (674, 811, 849, 956 nm) when the spatially resolved probe and FDPM are used. The spatially resolved probe shows optimum measurement sensitivity in the measurement volume immediately beneath the probe (typically 1 mm(3) in tissues), whereas FDPM typically samples larger regions of tissues. Optical-property values for human skull, white matter, scar tissue, optic nerve, and tumors are reported that show distinct absorption and scattering differences between structures and a dependence on the phase-function parameter gamma.

Utility and complications of permanent venous access devices (PVAD) in oncological treatments. Follow-up of 100 cases

BACKGROUND

Permanent venous access devices (PVAD) are nowadays routinely implanted and used with some morbidity for the oncological treatments. The adequate timing of implantation based on the number of treatments, the survival rate and the complications has not yet been well estimated.

METHODS

A hundred permanent venous access devices placed in oncological patients were followed-up prospectively.

RESULTS

No mortality was seen due to the surgical act. A 11% morbidity rate was noted, largely due to infections, with 6 patients needing a second surgery. On average, 6 chemotherapy cycles were done after placing of the permanent venous access device.

CONCLUSIONS

Due to these results and an average survival rate of 10.7 months, we suggest the placing of a permanent venous access device early in the management of oncological patients requiring chemotherapy cycles, so as to increase the comfort of the patient and to safeguard his peripheral venous system.

[Post-mortem evaluation following oncologic treatment of the functional and bacteriologic status of 25 permanent venous access devices]

Permanent venous access devices allow long-term parenteral treatment under relatively safe and comfortable conditions. Nevertheless, this use is associated with some degree of (particularly infectious) morbidity. 25 permanent access devices were removed surgically in immediate autopsies and cultured. Some half were infected, with a clear prevalence (40%) for Staphylococcus coagulase negative. The results were related to clinical history and compared with the figures and conclusions of other studies. It is proposed that in certain situations cultures of native blood should be carried out more frequently through the permanent venous access, with a view to possible specific targeted antibiotic therapy associated with the heparinized lock.

[A rare complication of permanent venous access: constriction, fracture and embolization of the catheter]

The pinch off syndrome due to squeezing of the implanted catheter is a rare complication of permanent venous access devices (0.1 to 1% of the cases). The cause is a mechanical catheter's compression in the costo-clavicular space, when implanted too medially in the subclavian vein. In case of lack of venous reflux or injection difficulties, sometimes complicated by local pain, a radiological control must be obtained to demonstrate signs of compression or beginning of fracture. Significant damage to the system is shown be extravasation of radioopaque contrast medium. The suspicion of catheter damage justifies early replacement of the system to avoid right heart or pulmonary artery embolism. The electron microscopic scanning tends to prove that the catheter's rupture is caused by a fatigue process.

Recombinant human granulocyte-macrophage colony-stimulating factor in acquired or chemotherapy-induced neutropenia. An open clinical trial

This prospective open trial evaluated the efficacy and tolerability of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) in patients with established neutropenia, considering as the main endpoint the clinical benefit to the patients regarding clearing of infection or resuming chemotherapy as initially planed. Adult patients (n = 28) with absolute neutrophil counts (ANC) < 10(9)/1 for 21 days were given a fixed dose (400 micrograms) of rhGM-CSF subcutaneously, for a total of 35 cycles. Causes of neutropenia were chemotherapy for acute leukaemia, lymphoma, myeloma and solid tumours, complications after bone marrow transplantation (BMT), and neutropenia associated with AIDS. Response (ANC to > 10(9)/l) occurred in 83% of rhGM-CSF cycles (29/35). Median time to response was 2.4 days (mean 6.7 days). Kinetics of response was dependent on diagnosis and treatment history. Fever abated with increasing ANC in 13/17 patients (76%) who entered the trial with hyperpyrexia. Treatment with rhGM-CSF allowed chemotherapy to be resumed on schedule in 7/9 relevant cycles. Toxicity was mild, leading to treatment interruption in only two cycles. In conclusion, rhGM-CSF was well tolerated and associated with a rise in ANC which appeared to result in immediate clinical benefit, including resolution of infection and resumption of scheduled chemotherapy.

[Secondary polycythemias: the role of erythropoietin]

The discovery of high hemoglobin and hematocrit values in a patient necessitates the determination of the red blood cell mass in order to confirm the absolute character of the polycythemia. If a true polycythemia is confirmed, its etiology must then be established. The diagnostic approach of polycythemia is presented in this paper. It is illustrated by a case presentation in which a polycythemia secondary to a renal carcinoma is discussed. Erythrocytosis is a classical, albeit rare manifestation of this type of tumor, and has the advantage of allowing early detection. Thus, it permits a prompt treatment plan, thereby improving the prognosis of such a neoplasia. The usefulness of a serum level of erythropoietin (EPO) is subsequently discussed. The diagnostic value of EPO remains controversial because of the overlapping values recorded amongst healthy patients, patients with polycythemia vera and others with secondary polycythemia. Finally, we discuss the presence of substances in paraneoplastic polycythemias whose biological activity is close to that of EPO. However, this molecules of a different structure would not be detected by the radioimmunoassay used to measure erythropoietin level.

[Schizophrenia and language disorders]

The speech of schizophrenics is idiosyncratic, possibly unrelated to thought disorders. Review of relevant literature indicates that schizophrenic speech disorders include: errors in the use of pronouns, articles, verbs and verb tenses, which are neither pointed out or corrected; absence of redundancy, skewering of the meaning of words, faulty establishment of common references with others. Sentences appear disjointed due to improvised vocabulary and the scant use of conjunctions and other linking words or phrases. Speech is slow, trite, and fails to convey information proportionate to speech production. Discourse is self-centered and the needs of others are ignored. In general, schizophrenic speech performance worsens the more ambiguous, intimate or complex the topic.

Histopathology of myelodysplastic syndromes. The FAB classification (proposals) applied to bone marrow biopsy

Twenty-eight cases of myelodysplastic syndrome (MDS) were reviewed to evaluate whether the morphologic criteria proposed by the French-American-British (FAB) Cooperative Group for marrow smears could be applied to glycol methacrylate embedded trephine biopsies. Bone marrow biopsies and marrow smears were examined separately and then compared for the following parameters: percentage of blasts, dyserythropoiesis, ring sideroblasts, dysmegakaryopoiesis, dysgranulopoiesis, monocytes, cellularity, fibrosis, and "abnormal localization of immature precursors". The results of the histologic (biopsies) and cytologic (marrow smears) examinations were in good agreement in 24 of 28 cases. The authors' results suggest that the five MDS types proposed by the FAB group can be reliably distinguished on bone marrow biopsy with knowledge of the peripheral blood blast and monocyte counts. When the bone marrow aspiration is inadequate, the biopsy can establish diagnosis and type of MDS and rules out aplasia or tumor infiltration as possible alternative causes of cytopenia.

Ring chromosomes and hematologic disorders

Based on 5 years of cytogenetic evaluation in hematology, we report our observations on various hematologic proliferative disorders with ring chromosomes. Comparing our data to those previously published in the literature we analyzed the occurrence of the ring in relation to the age of onset, previous history of therapeutic or professional exposure to mutagenic agents, and mean survival. It is concluded that the presence of ring chromosomes may be linked to a poor prognosis.