Biomedical subjects

Michel Aubé

Publications and source records attributed to Michel Aubé.

6 recordsLinked to original sources

PubMed2003

Fanconi anemia genes are highly expressed in primitive CD34+ hematopoietic cells.

BACKGROUND: Fanconi anemia (FA) is a complex recessive genetic disease characterized by progressive bone marrow failure (BM) and a predisposition to cancer. We have previously shown using the Fancc mouse model that the progressive BM failure results from a hematopoietic stem cell defect suggesting that function of the FA genes may reside in primitive hematopoietic stem cells. METHODS: Since genes involved in stem cell differentiation and/or maintenance are usually regulated at the transcription level, we used a semiquantitative RT-PCR method to evaluate FA gene transcript levels in purified hematopoietic stem cells. RESULTS: We show that most FA genes are highly expressed in primitive CD34-positive and negative cells compared to lower levels in more differentiated cells. However, in CD34- stem cells the Fancc gene was found to be expressed at low levels while Fancg was undetectable in this population. Furthermore, Fancg expression is significantly decreased in Fancc -/- stem cells as compared to wild-type cells while the cancer susceptibility genes Brca1 and Fancd1/Brac2 are upregulated in Fancc-/- hematopoietic cells. CONCLUSIONS: These results suggest that FA genes are regulated at the mRNA level, that increased Fancc expression in LTS-CD34+ cells correlates with a role at the CD34+ differentiation stage and that lack of Fancc affects the expression of other FA gene, more specifically Fancg and Fancd1/Brca2, through an unknown mechanism.

Journal Article↗

PubMed2002

Improving patient compliance to prophylactic migraine therapy.

As in many other chronic conditions, adherence to prophylactic treatment in migraine is probably poor. In chronic diseases, compliance at one year does not exceed 50%. That could explain the low therapeutic gain seen with migraine preventive medications. It also renders difficult the evaluation of clinical trials on migraine prophylaxis since in most of these trials compliance is not properly assessed. From the patients' perspective, there are several factors that could explain poor adherence to recommended treatments. Essentially, these factors are the expression of the patients' subjective perception of their disease and potential remedies in a context of a positive patient-physician relationship. When migraine prophylactic treatment is considered, patients should be informed of the natural history of their disease and a diagnosis of an accelerated form of migraine should be confirmed. Prophylactic treatment at best would reduce by 50% the frequency of migraine attacks. In most studies, however, the therapeutic gain is in the order of 30-40%. Treatment should be instituted for a minimum time of two to three months and if effective maintained for 6-12 months. The outcome of prophylaxis can rarely be determined in a prospective way. The choice of prophylactic regimens remains empirical, often based on the physician's experience and perception of the mechanism of migraine. A better adherence to prophylactic treatment of migraine could possibly improve outcomes but current methods of improving adherence for chronic health problems are mostly complex and not very effective.

Humans↗

PubMed2002

A headache diagnosis project.

BACKGROUND: Despite the availability of objective criteria, the diagnosis of migraine is thought to be missed frequently in primary practice. OBJECTIVE: To determine the most important questions assisting in the clinical diagnosis of migraine headache. METHODS: A cohort of 461 patients referred to headache specialists in Canada was assessed using a pro-forma questionnaire that was completed by the patients alone or administered by the physicians themselves. A final clinical diagnosis was recorded after a complete clinical evaluation. In a subsequent validation study, three questions derived from the results of the first phase of the study were administered to a new cohort of 128 patients, and diagnoses of "migraine" or "not migraine" were recorded according to the decision generated in the first part of the study. The final clinical diagnosis was taken as the "gold standard" for diagnosis, and the results from the two independently derived diagnostic methods were compared. RESULTS: Statistical analysis of the responses from part 1 of the study yielded three questions (related to daily occurrence, unilaterally, and functional impairment) that distinguished between pure migraine and other headache diagnoses with high reliability and validity. The sensitivity and selectivity of the three-question protocol exceeded 91%. CONCLUSIONS: The use of three questions related to headache frequency, laterality, and impact on functioning may represent an attractive screening instrument in primary care practice, alerting physicians to the diagnosis of migraine in patients or to the possibility of a second or alternative headache diagnosis in patients in whom their diagnosis of migraine previously has been made. The presence of multiple headache syndromes in individual patients, as is common in tertiary referral practice, may reduce the discriminating power of the three-question protocol.

Adult↗

PubMed2002

Melatonin as adjunctive therapy in the prophylaxis of cluster headache: a pilot study.

BACKGROUND: The periodicity of cluster headache suggests involvement of the suprachiasmatic nucleus of the hypothalamus, the biological clock. The secretion of melatonin, a hormone produced by the pineal gland and regulated by the suprachiasmatic nucleus, is altered in patients with cluster headache. Melatonin shifts circadian rhythms. A previous study of melatonin for primary prophylaxis of cluster headache demonstrated a 50% response rate. OBJECTIVE: To evaluate the use of melatonin as adjunctive therapy in patients with cluster headache who have incomplete relief of their headaches on conventional therapy. METHODS: Nine patients participated in the study, six with chronic cluster headache and three with episodic cluster headache. Patients with chronic cluster headache completed a baseline diary for 1 month, followed by 1 month of melatonin treatment, then 1 month of placebo. Patients with episodic cluster headache received placebo for 1 month, then melatonin for 1 month. Patients continued their usual prophylactic and abortive treatments during the study. Headache frequency, intensity, and use of analgesics were recorded. The primary endpoint of the study was the mean number of headaches per day, with mean daily analgesic consumption and percentage of mild, moderate, and severe headaches as secondary endpoints. RESULTS: There were no significant differences between means on analysis of variance and t testing for the melatonin, placebo, and baseline months for all primary and secondary endpoints. There were no side effects reported. CONCLUSIONS: Patients with chronic cluster headache or patients with episodic cluster headache whose headaches are uncontrolled on conventional therapy do not appear to gain therapeutically from the addition of melatonin to their usual treatment regimens. It is perhaps the phase-shifting properties of melatonin that mediate its effect in patients with episodic cluster headache, and it may be necessary to treat from the beginning of the cluster bout to reset the circadian pacemaker, thus producing a more positive outcome.

Adjuvants, Immunologic↗

PubMed2002

Hematopoietic stem cells from fancc(-/-) mice have lower growth and differentiation potential in response to growth factors.

Fanconi anemia (FA) is a complex recessive genetic disease characterized by progressive bone marrow (BM) failure. We have previously shown that stem cells from the FA group C mouse model have lower long-term primary and secondary reconstitution ability, and that bone marrow of Fancc(-/-) mice contained fewer lineage-negative (Lin(-))Thy1.2(low)Sca-1(+)c-kit(+) CD34(+) cells but normal levels of Lin(-)Thy1.2(low)Sca-1(+)c-kit(+)CD34(-) primitive cells. These data suggest that CD34(+) primitive cells have either a lower growth or differentiation potential, or that these cells have greater apoptosis levels. To investigate the role Fancc might have on the growth and differentiation potentials of primitive hematopoietic stem cells, we used a single-cell culture system and monitored cell viability, doubling potential, and apoptosis levels of Fancc(-/-) primitive Lin(-)Thy1.2(-)Sca-1(+) (LTS)-CD34(+) and LTS-CD34(-) stem cells. Results showed that Fancc(-/-) LTS-CD34(-) and LTS-CD34(+) cells had altered growth and apoptosis responses to combinations of stimulatory cytokines, most dramatically in response to a combination of factors that included interleukin-3 (IL-3) and IL-6. In addition, Fancc(-/-) LTS-CD34(-) and LTS-CD34(+) cells showed a lower differentiation potential than Fancc(+/+) cells. These results support a role for Fancc in the growth and differentiation of primitive hematopoietic cells and suggest that an altered response to stimulatory cytokines may contribute to BM aplasia in FA patients.

Animals↗

PubMedDate not supplied

A clinical study of migraine evolution.

BACKGROUND: The buildup time of migraine headaches has not been well delineated in publications to date and we are aware of patients whose migraines last well over 72 hours. More concentration on these factors in the assessment of patients might lead to more appropriate therapeutic choices. METHOD: Prospective ascertainment of such data through a questionnaire completed by 253 informed and willing patients with IHS migraine with or without aura consulting Canadian headache specialists. Data were electronically sent to a central computer from each center, tabulated and analyzed using standard statistical parameters. RESULTS: In 253 patients with migraine ascertained using applied IHS criteria, nausea was a feature in over 90% of cases, especially in those with aura. This inhibited the ingestion of oral medications in about a quarter of all subjects. The time to build from no pain to moderate/severe pain was shorter in subjects with auras and was less than 2 hours in 97% of those with and 86% of those without auras. However, we also identified a group of subjects with migraine (over 10% of all) in whom the build time to maximum pain is delayed for over 2 hours. Nausea was experienced by 91.7% of subjects, slightly but significantly later in those without auras. While most headaches in each group lasted from 4 to 72 hours, 24.3% of those with and 20.6% of those without aura expected to experience pain for more than 72 hours, while in untreated cases disability due to pain, nausea, or malaise usually persisted for over 3 days in 24.3% and 16.7% of those with and without aura, respectively. One-fifth of migraineurs may be in pain and/or disabled by accompanying symptoms for over 3 days in a typical migraine attack. Over half of our subjects reported that their medications worked well or excellently. CONCLUSIONS: Attacks of migraine in real-life clinical situations vary somewhat from the IHS criteria in that they are more often associated with nausea that interferes with oral therapy; can persist for over 72 hours; may have slow (>2 hours) buildup to maximum pain in 10% of cases; and may cause disability for over 3 days. Nevertheless, current therapeutic regimens (including prescribed medications) work well for a substantial majority.

Adult↗