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Biomedical subjects

P Henry

Publications and source records attributed to P Henry.

At least 109 records · Page 6Linked to original sources
PubMed1993

Restriction/modification in Streptococcus thermophilus: isolation and characterization of a type II restriction endonuclease Sth455I.

Streptococcus thermophilus strain CNRZ 455 produces a type II restriction endonuclease designated Sth455I. This enzyme was isolated from cell extracts by anionic and cationic exchange chromatography. This yielded an enzyme preparation free of non-specific nucleases. The optimal reaction conditions for Sth455I are: MgCl2, 30 mM; pH range, 8-9; incubation temperature, 37-42 degrees C; and a high NaCl concentration, 100-200 mM. The results of single- and double-digestion experiments indicates that Sth455I is an isoschizomer of BstNI and EcoRII showing different sensitivity to methylation. The enzyme exhibits restriction activity on the DNA of three bacteriophages of S. thermophilus and no activity on the phage lytic for strain CNRZ 455. The restriction/modification system associated with this strain is discussed.

Bacterial Proteins↗
PubMed1993

Pulsatile TSH secretion during 48-hour continuous TRH infusions.

Thyroid-stimulating hormone (TSH), like other anterior pituitary hormones, is normally secreted in a series of pulses over 24 h. However, the factors that control TSH pulse generation are unknown. We investigated the potential role of thyrotropin-releasing hormone (TRH) in TSH pulse generation by measuring TSH pulses during constant TRH infusions. Two groups of subjects were studied: five healthy subjects and five subjects with treated primary hypothyroidism and normal TSH levels. Each subject underwent four separate studies: (1) TSH levels were measured every 15 min over 24 h (baseline study). (2) TSH levels were measured every 15 min over 48 h during TRH infusions at 0.1 microgram/min (low dose TRH study). (3) TSH levels were measured every 15 min over 48 h during TRH infusion at 0.5 microgram/min (medium dose TRH study). (4) TSH levels were measured every 15 min over 48 h during TRH infusions at 1.0 microgram/min (high dose TRH study). TSH pulses were located by cluster analysis. We found that constant TRH infusions at any of the doses utilized did not alter TSH pulse frequency in normal or treated hypothyroid subjects, although pulse amplitude increased. Normal subjects had lower TSH pulse amplitude than treated hypothyroid subjects at all TRH doses, perhaps due to slightly higher serum T3 levels. This suggests that, at least acutely, pulsatile input of TRH to the pituitary gland does not determine pulsatile TSH release. However, TRH may modulate TSH pulse amplitude.

Adult↗
PubMed1993

Potassium channels as pharmacological targets in cardiovascular medicine.

Potassium channels are membrane receptor sites for various drugs in the field of cardiovascular diseases. These channel proteins are extremely diverse, not only as regards their molecular structure but also as regards their function. Heterogeneous expression of various K+ channel subtypes is an integral part of cell specialization in different tissues. K+ channels interfere with most of the physiological processes of the cardiac muscle, of the vascular smooth muscle and of the endothelial cells. K+ channel blockers are antidiabetic agents but also antiarrhythmic drugs. K+ channel openers are used in the treatment of hypertension and most recently in the treatment of coronary heart disease. In the experimental setting, K+ channel openers afford cytoprotection during ischaemia. This exciting property opens a new field in clinical research.

Adenosine Triphosphate↗
PubMed1993

Subcutaneous sumatriptan in the acute treatment of migraine in patients using dihydroergotamine as prophylaxis. French Migraine Network Bordeaux-Lyon-Grenoble.

The efficacy of sumatriptan, a 5-HT1 receptor agonist, in patients with migraine attacks occurring despite prophylactic treatment with oral dihydroergotamine, was assessed in a double-blind placebo-controlled study involving 76 patients. Thirty-seven patients were treated with a subcutaneous injection of 6 mg sumatriptan self-administered with an auto-injector and 39 with placebo given by the same route. Patients having inadequate relief were allowed to use a second injection of test medication 1 hour later and rescue treatment between 2 hours and 24 hours after the first dose. Headache relief was achieved within 2 hours after sumatriptan in 26 patients (70%) compared to 8 patients (21%) in the placebo group (P < 0.0001). Of these patients, 19 (51%) and 3 (8%) were, respectively, pain free at this time. A second injection of sumatriptan was used by 8 (22%) patients compared to 30 (77%) patients in the placebo group (P < 0.0001), whereas rescue medication was used respectively by 13 (35%) and 22 (58%) patients (P < 0.024). The adverse event profile of sumatriptan was not affected by the concomitant use of dihydroergotamine and side-effects were all minor and transient. Patient satisfaction was significantly higher in the sumatriptan group (75%) compared to patient satisfaction with placebo (16%). These results show that the high efficacy rate of subcutaneous sumatriptan and its safety profile remain unchanged in migraine patients receiving oral dihydroergotamine as prophylaxis.

Acute Disease↗
PubMed1993

Validity of the International Headache Society criteria for migraine. GRIM. Groupe de Recherche Interdisciplinaire sur la Migraine.

For general practitioners and in epidemiological studies, migraine poses diagnostic problems. It is a polymorphous disease, with diagnosis based on a subjective description of symptoms. The International Headache Society (IHS) proposed a set of rigorous criteria for the diagnosis of migraine. We studied its validity on 171 outpatients of headache clinics and on 96 headache sufferers detected during an annual checkup for workers. The criteria showed an excellent specificity, however sensitivity in both samples was < 50%. This lack of validity could be due to IHS criteria being too restrictive. We therefore elaborated and validated our own diagnostic tool, based on the IHS criteria, to a sensitivity of 95% and a specificity of 78%. We propose our tool for epidemiological studies.

Adolescent↗
PubMed1993

Diagnostic screen for assessment of the IHS criteria for migraine by general practitioners.

This study examines the sensitivity and specificity of a self-report screen for the diagnosis of migraine according to the IHS criteria in a sample of 1049 employees of the French National Railways. The diagnosis of migraine derived from the self-report instrument was compared to an unstructured diagnostic interview conducted by a neurologist specialized in the diagnosis and treatment of headache. The sensitivity of the diagnostic screen was poor, but the specificity was excellent. Optimal cut-off points for the questionnaire were determined by the Receiver Operator Characteristics (ROC) method. Assessment of the specific IHS criteria for migraine revealed that the following criteria failed to discriminate subjects with migraine from non-cases: "aggravation by physical activity" and "photophobia and phonophobia". Implications of the findings for modification of the IHS criteria were discussed.

Adult↗
PubMed1993

Effectiveness of career-development courses for nontraditional premedical students: improving professional identity.

The purposes of this study were to examine the effects of three career-development courses on the professional identities of participating students as measured by My Vocational Situation and to investigate the effect of gender on students' responses to the scale. A total of 64 students enrolled in a special premedical program took the scale as a pretest and again as a posttest after the completion of three career-development courses. Analysis yielded significant differences between pre- and posttest scores for the three subscales of Vocational Identity, Occupational Information, and Barriers. No significant gender differences were observed at pre- or posttest. Implications for further research designed to evaluate the effectiveness of intervention strategies in career development are discussed.

Adult↗
PubMed1993

Effects of the 21-aminosteroid U-74389G on ischemia and reperfusion injury of the ascending colon in horses.

Sixteen horses were allotted at random to 3 groups: vehicle only; low dosage (vehicle and 3 mg of U-74389G/kg of body weight); high dosage (vehicle and 10 mg of U-74389G/kg). These solutions were given prior to reperfusion. The ascending colon was subjected to 2 hours of ischemia followed by 2 hours of reperfusion. Before, during, and after ischemia, full-thickness colonic tissue biopsy specimens were obtained for measurement of malondealdehyde (MDA) concentration and myeloperoxidase activity and for morphologic evaluation. Although increases were not significant, MDA concentration and myeloperoxidase activity increased during ischemia and reperfusion. Administration of U-74389G did not have significant effects on MDA concentration and myeloperoxidase activity. However, the lower dosage tended (P = 0.08) to reduce myeloperoxidase activity at 30 and 60 minutes of reperfusion. In horses of the vehicle-only group, ischemia induced a decrease in mucosal surface area that was continued into the reperfusion period (P < or = 0.05). Administration of U-74389G at both dosages (3 and 10 mg/kg) prevented the reperfusion-induced reduction in mucosal surface area, which was significant at 60 minutes (high dosage; P = 0.05) and 90 minutes (low and high dosages; P = 0.02). After initial reduction in horses of all groups, mucosal volume increased for the initial 60 minutes of reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1992

Permanent bruxism as a manifestation of the oculo-facial syndrome related to systemic Whipple's disease.

We report here a new case of oculomasticatory syndrome related to systemic Whipple's disease. The patient presented typical ophthalmoparesis associated with ocular myorhythmia consisting of 1 Hz convergent oscillations of both eyes. The masticatory involvement was remarkable and consisted of a permanent bruxism leading to severe tooth abrasions. Possible pathophysiology of such a disorder is discussed.

Bruxism↗
PubMed1992

A nationwide survey of migraine in France: prevalence and clinical features in adults. GRIM.

In November 1990 a nationwide survey of migraine was conducted in France on a representative sample of residents aged 15 years and older. The diagnosis of migraine was based on the International Headache Society (IHS) classification. In a previous study, we validated a diagnostic algorithm which classifies headache sufferers as IHS migraine, "borderline" migraine, possible migraine and non-migrainous headache. The overall prevalence of migraine patients with the IHS criteria in the present study was 8.1%; another 4% were classified as "borderline" migraine, which we in fact considered as definite migraine. Age, gender and occupation were found to be risk factors for migraine. Neither frequency and duration of attacks nor length of time of disease differed with gender. Expressed intensity of attacks, however, was greater in females.

Adolescent↗
PubMed1992

Optimal electrolytic chloriding of silver ink electrodes for use in electrical impedance tomography.

The electrode-electrolyte interface impedance may be simplistically modelled by an equivalent circuit comprising a resistance, RTOTAL, in series with an empirical, constant phase angle impedance, ZCPA. This pseudo-capacitance can be thought of as representing empirically the non-faradaic, double layer capacitance in the presence of specific adsorption and surface roughness effects. RTOTAL is the sum of the lead and electrolyte resistances. Depositing a thin layer of silver chloride on silver electrodes can yield improved electrical performance characteristics (potential and impedance) when used in conjunction with a chloride gel. An electrolytically deposited AgCl layer tends to have a rough surface profile thus leading to an increase in the effective interface area. This gives rise to a decrease in RTOTAL and ZCPA, both of which are desirable. Unfortunately AgCl is a relatively poor conductor. Increasing layer thickness causes RTOTAL to increase, thus adversely affecting the inter-electrode impedance at high frequencies. Electrode systems for use in electrical impedance tomography therefore require only relatively thin layers of AgCl.

Electric Conductivity↗
PubMed1992

Effects of dopamine and somatostatin on pulsatile pituitary glycoprotein secretion.

The hypothalamic factors dopamine (DA) and somatostatin (SRIH) inhibit pituitary glycoprotein secretion, but little is known regarding the effects of these factors on glycoprotein pulses. To address this question, 12 healthy volunteers underwent frequent blood sampling over 12 h at baseline and during 12-h infusions of DA and/or SRIH. TSH, LH, FSH, and alpha-subunit (alpha) levels were measured in all samples, and hormone pulses were located by Cluster analysis. Both DA and SRIH suppressed TSH pulse amplitude by 70%, while SRIH decreased TSH pulse frequency as well. Both infusions decreased LH pulse amplitude by 30-35%, but had no effect on pulse frequency. In contrast, neither infusion significantly altered FSH pulse parameters, although mean FSH levels declined 15%. DA had no effect on pulsatile alpha secretion, while SRIH decreased alpha pulse frequency. Serum thyroid hormone levels declined during both infusions, but there were no major changes in serum sex steroid levels. Thus, the hypothalamic inhibitory factors DA and SRIH had divergent effects on glycoprotein hormone pulses. The major effects on pulse amplitude, rather than frequency, imply that these factors do not play major roles in the generation of glycoprotein pulses, although SRIH may directly affect the TSH and alpha pulse generators.

Adolescent↗
PubMed1992

Choice of medical specialty: analysis of students' needs.

The purposes of this study were to assess the career development needs of entering medical students as measured by the Medical Career Development Inventory and to examine gender differences in responses to the inventory. A total of 115 entering medical students (representing two entering classes) took the inventory two months prior to matriculation. Analysis suggested that this sample of entering students had formed a vocational identity and that they had evaluated the suitability and viability of a commitment to a physician's career. However, the participants had not formed a clear picture of their specialty interest and goals. No significant gender differences were indicated. A recommended career assistance workshop is presented as appropriate for these students' needs.

Adaptation, Psychological↗
PubMed1992

[Pilot study of Ginkgolide B, a PAF-acether specific inhibitor in the treatment of acute outbreaks of multiple sclerosis].

Ten patients with relapsing-remitting multiple sclerosis in acute relapse were treated with a five-day course of intravenous ginkgolide B, a specific inhibitor of PAF-acether. Eight patients had improvement of their neurological score, beginning 2 to 6 days after the initiation of therapy. This improvement was sustained in 5 patients and only transient in 3. Two out of these 3 patients with secondary failure and the other 2 who did not respond to ginkgolide therapy, received i.v. methylprednisolone. Three patients experienced mild side effects under ginkgolide therapy but none of the patients had any serious adverse effect. A controlled randomized study is underway, in order to confirm these results and test higher dosages and more prolonged administration.

Adult↗
PubMed1992

[Migraine according to the International Headache Society].

The classification of headache and facial pain established by the International Headache Society (IHS) in 1988 is a useful tool for general practitioners, specialists and scientists. This classification provides a detailed description of the diagnostic criteria for the different forms of migraine headache, ranging from common migraine with or without an aura to less frequent or atypical forms such as migraine without headache or periodic syndromes of childhood.

Adolescent↗