Biomedical subjects

D Piguet

Publications and source records attributed to D Piguet.

12 recordsLinked to original sources

PubMed2002

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.

Journal Article↗

PubMed2002

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.

Adult↗

PubMed2000

Chemical characterization of bohrium (element 107)

The arrangement of the chemical elements in the periodic table highlights resemblances in chemical properties, which reflect the elements' electronic structure. For the heaviest elements, however, deviations in the periodicity of chemical properties are expected: electrons in orbitals with a high probability density near the nucleus are accelerated by the large nuclear charges to relativistic velocities, which increase their binding energies and cause orbital contraction. This leads to more efficient screening of the nuclear charge and corresponding destabilization of the outer d and f orbitals: it is these changes that can give rise to unexpected chemical properties. The synthesis of increasingly heavy elements, now including that of elements 114, 116 and 118, allows the investigation of this effect, provided sufficiently long-lived isotopes for chemical characterization are available. In the case of elements 104 and 105, for example, relativistic effects interrupt characteristic trends in the chemical properties of the elements constituting the corresponding columns of the periodic table, whereas element 106 behaves in accordance with the expected periodicity. Here we report the chemical separation and characterization of six atoms of element 107 (bohrium, Bh), in the form of its oxychloride. We find that this compound is less volatile than the oxychlorides of the lighter elements of group VII, thus confirming relativistic calculations that predict the behaviour of bohrium, like that of element 106, to coincide with that expected on the basis of its position in the periodic table.

Journal Article↗

PubMed1999

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.

Adolescent↗

PubMed1998

[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.

Adult↗

PubMed1998

[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.

Aged↗

PubMed1994

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.

Acquired Immunodeficiency Syndrome↗

PubMed1993

[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.

Algorithms↗

PubMed1987

[Retrospective study of 30 cases of myelodysplastic syndrome according to the French-American-British classification].

The bone marrow smears and marrow biopsies of 30 unselected consecutive patients with a myelodysplastic syndrome have been classified retrospectively according to the proposals of the French-American-British cooperative group (FAB). The diagnoses according to the FAB classification were refractory anemia (RA) in 3, RA with ring sideroblasts (RAS) in 5, RA with excess of blasts (RAEB) in 14, REAB in transformation (RAEB-t) in 5, and chronic myelomonocytic leukemia (CMML) in 3. The group comprised 19 men and 11 women with a median age of 68 years. Of 22 patients, 9 died after progression to acute non lymphoblastic leukemia (ANLL), 7 from infections, 2 from bleeding and 4 from unrelated causes. Actuarial survival is 10.5 months, 8 patients being at risk at the time of evaluation. Although the small number of patients does not allow statistical evaluation, our results are similar to those in the literature: prognosis is less good with an increasing number of marrow blasts and degree of cytopenia, and the risk of progression to ANLL is higher for REAB-t and REAB patients. Of 4 patients treated with small doses of cytosine-arabinoside (Ara-C), one responded and remained stable without treatment for 7 months. 2 patients resistant to small-dose Ara-C showed complete response to subsequent high-dose Ara-C treatment.

Aged↗

PubMed1987

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.

Adult↗

PubMed1986

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.

Adult↗

PubMedDate not supplied

[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.

Communication↗