PubMed HealthSearch

Biomedical subjects

A Hirsch

Publications and source records attributed to A Hirsch.

At least 19 recordsLinked to original sources

Heterofullerenes: structure and property predictions, possible uses and synthesis proposals.

Substituting carbon atoms of fullerenes by heteroatoms and vacancies will lead to new and yet unknown spherical-shaped molecules termed hereafter as heterofullerenes. The enormous structural diversity of these molecules is investigated and their structural, electronic and thermochemical properties are predicted using semiempirical computations. Computational results for complexes with ions lead to the hypothesis that these molecules behave like microscopic Faraday cages in which the electrons concentrate on the outer side of the sphere. It is predicted that some of these heterofullerenes are structurally and electronically similar to phthalocyanines and related molecules but offer many additional advantages. Potential uses such as adding heterofullerenes to fullerene materials, as superior starting materials for the fabrication of diamonds, as catalysts in hydrogenation reactions, as components of materials dominated until now by phthalocyanines, etc., are discussed. Simple synthetic routes to these compounds that are based on minor alternations of existing methods for fullerene production are proposed. On the basis of the thermochemical calculations, we believe that the most promising possibility consists of using metal cyanide/graphite composite target rods instead of pure graphite rods as in a conventional fullerene synthesis.

Carbon

Molecular mechanism of contractile dysfunction in cardiac allograft rejection.

Alterations in the beta-adrenergic receptor adenylyl cyclase pathway are well known in heart failure. To determine if an alteration in this pathway occurs during the reversible phase of cardiac allograft rejection, we used a rat heterotopic heart transplant model. Lewis rats received either isografts or Lewis Brown Norway allografts. Cardiac grafts and native hearts were explanted 4, 5, or 6 days later. Receptor-mediated modulation of adenylyl cyclase activity was investigated using isoproterenol, forskolin, and the muscarinic and adenosine receptor agonists carbachol and R-N6-(C2-phenyl-isopropyl)-adenosine (R-PIA), respectively. Allografts demonstrated evidence of histological rejection and a significantly impaired response to forskolin and isoproterenol on all days: [table: see text] (% increase in cAMP in response to forskolin or isoproterenol +/- standard error. All results P less than 0.03 except Day 4 forskolin and Day 5 isoproterenol.) No significant difference was noted between isografts and allografts stimulated with carbachol and R-PIA. These data suggest that a primary alteration in adenylyl cyclase activity may be a component of the molecular basis of reversible contractile dysfunction in cardiac allograft rejection.

Adenylyl Cyclases

Anti-tobacco measures in the world: the French case.

The devastating long-term effects of tobacco smoking registered in the developed world and now imminent in the developing world must be responded to on national and international levels. In France, governmental tobacco control action began in 1976. Despite the high rates of premature mortality among men and women, legislative controls that were introduced were not enforced. Over the past decade, overall smoking prevalence has remained stable, reflecting growth in women's rates which compensates declines in men's rates. Comprehensive tobacco control measures should include prohibiting tobacco advertising, real tobacco retail price increases and regulations protecting non-smokers in public places. New legislation was voted in 1991 both in France and in the European Community. These measures, reinforced by a framework of continuing public education, may be an important step towards effective health promotion.

Advertising

[Value of magnetic resonance imaging in the detection of intramedullary metastases of bronchial epidermoid carcinoma].

A 68 year old female presented with an intramedullary metastasis which was found to be caused by an epidermoid bronchial carcinoma. This type of metastasis is a rare complication and a diagnosis is difficult. The authors stress the importance of nuclear magnetic resonance as a non-aggressive diagnostic method which is very sensitive in detecting this type of pathology.

Aged

[Stages of grief in coping with diabetes?].

Forms of coping with diabetes were determined on the basis of self-ratings of emotions (depressive, sad, angry, anxious) and responses on a 30-item "stages of grief" questionnaire by 52 inpatients aged between 25 and 50 (diabetes duration 1 to 35 years) at the beginning of a 12 day diabetes education program. Psychometric qualities of the instruments were evaluated. To test empirically the notion of grief stages in coping with diabetes, the frequency of emphasis on one or more emotional areas or stages of grief was determined and tested to ascertain whether various conditions occurred more frequently than was expected by chance. Results indicated that shortly after diabetes manifestation scores on protest and depression with respect to diabetes were elevated. The majority of cases could not be assigned to a single emotion or stage of grief but displayed negative emotional reactions in different content areas simultaneously. Consequently the concept of grief stages for coping with diabetes as well as recommendations based on this concept are questioned.

Adaptation, Psychological

Isolation, characterization and sequencing of the chicken apolipoprotein-AI-encoding gene.

The chicken ApoAI gene has been isolated and characterized. This gene contains three introns: the first is situated after nucleotide (nt) 41 in the 5'-untranslated region of the gene, the second interrupts the codon specifying the Gly-10 of the prepeptide, and the third disrupts the codon for Asp42 in the mature ApoAI protein. The chicken ApoAI gene has 62.6% sequence similarity with the human and 65.0% similarity with the rat gene. Intron-exon organization of the chicken gene is similar to that of human and rat ApoAI genes. Two different transcriptional start points (tsp), only 2 nt apart from each other, have been obtained for the chicken ApoAI gene. The 5'-flanking sequence of the gene contains TAAATA (TATA-like box) and CCACAT (CCAAT-like box) sequences, which are located 21 bp and 96 bp upstream from the tsp, respectively. This gene's sequence and structural organization provide a basis for future studies of the regulation of chicken ApoAI gene expression.

Amino Acid Sequence

Effects of endothelin-1 in the isolated heart in ischemia/reperfusion and hypoxia/reoxygenation injury.

The effects of the vasoconstrictor peptide endothelin-1 were examined in the isolated heart during hypoxia, reoxygenation and reperfusion. Isovolumic rat hearts were perfused with Krebs-Henseleit buffer at constant pressure. Cumulative dose-response curves were obtained for endothelin-1 boluses of 0.04 to 400 pmol in five groups of hearts. Coronary flow declined with increasing dosages and was almost abolished at 400 pmol in control hearts. In hearts subjected to mild hypoxia (perfusate PO2 approximately 150 mmHg), the constrictor effect of endothelin-1 was attenuated at moderate dose compared to control hearts (4 vs. 16% flow reduction at 40 pmol; P less than 0.05). The constrictor effect was unaltered in hearts subjected to either 60 min of severe hypoxia (PO2 approximately 35 mmHg) followed by reoxygenation or to 10 min of total ischemia followed by reperfusion (stunning). When hearts were reperfused following 30 min of total ischemia (irreversible injury), the constrictor response to endothelin-1 was potentiated compared to control (e.g. 36 vs. 16% flow reduction at 40 pmol; P less than 0.05). We conclude that endothelin-1 is a potent coronary constrictor in hypoxic, reoxygenated and reperfused heart. The constrictor effect is attenuated during hypoxia, most likely due to the presence of counteracting vasodilator metabolites. During reperfusion, the constrictor effect is unchanged in stunned myocardium, but is augmented in irreversibly injured heart, due to either increased endothelin-1 binding sites or loss of counteracting vasodilator mechanisms such as prostaglandins and/or endothelium-derived relaxing factor.

Animals

Behavioural tests: applications and limitations in comparison with brainstem response audiometry.

Conditioned behavioural hearing tests cannot be performed in children before the developmental age of 8 months. Informal tests cannot be used as threshold tests as the stimuli are unspecific in frequency, and the observed reactions are not equivalent to the threshold level. Brainstem response audiometry (BRA) was performed on 47 children (23 normal children and 24 children with mental retardation with or without behavioural disturbances) in whom informal test results were unclear. The BRA was followed up by behavioural tests 1 to 10 years later. In none of the cases did the BRA thresholds indicate better hearing function than the actual threshold noted later on at behavioural tests. High BRA thresholds (up to 75 dB nHL) were found in 5 normal-hearing children with serous otitis media at the time of BRA recording.

Age Factors

[Granulo-monocyte growth factors. Their value in pneumonologic oncologic practice].

Granulo-monocytic growth factors are important members of the family of growth factors which alter the biological response. These factors are glycoproteins and are hormones regulating the production of haematopoietic cells and show their adaptation to possible needs. There are four which are currently well recognised; they are now grouped collectively under the term colony-stimulating factor and of these two, GM-CSF and G-CSF are available thanks to genetic engineering and have reached the stage of therapeutic trials. It is essentially the treatment of solid tumours which should lead to the most profound changes in the current management of cytotoxic drugs because they may allow an increase of the dose and a shortening of the duration of the phase of neutropenia and thus the infection risk. In therapeutic pneumonology they would be able to be used as an adjuvant to chemotherapy in small cell cancers and available in protocols using polychemotherapy with a risk of marrow suppression, indeed even permitting the practice of intensified chemotherapy regimes with or without the support of bone marrow graft. However the clinical experience acquired using growth factors remains limited and is almost exclusively restricted to the haematological domain. Although the secondary effects appear tolerable their harmlessness--and notably the absence of a stimulating effect on tumour growth--remains to be shown before extension of their use will lead to any changes of therapeutic strategies.

Antineoplastic Agents

[Detection of bronchial cancer. Realities and perspectives].

Primary bronchial cancer is responsible for at least 20,000 deaths per year in France. The treatment of cancer in the clinical phase remains disappointing. Numerous trials, which are reviewed here chronologically, have looked for a way to improve the prognosis by an earlier detection of this tumour. Unfortunately numerous methodological approaches have not been able to avoid the fact that the real value of such an early diagnosis is not always known. The only clear conclusion of these studies is that cytological examination of the expectorate does not lead to an improved survival in patients when compared to that which is obtained with the single radiographic film. However, taking account of the natural history of the disease, it is probably necessary to abandon the concept of an early diagnosis of a tumour which is already too late; it is towards a search for pre-cancerous lesions which are still reversible that the research effort should be turned.

Bias

Left ventricular hypertrophy reversal with labetalol and propranolol: a prospective randomized, double-blind study.

Hypertensive patients with left ventricular hypertrophy (LVH) have increased cardiovascular morbidity and mortality. Experimental studies indicate the importance of both the alpha and beta components of the adrenergic nervous system in the development and reversal of LVH. Therefore labetalol (L), a combined alpha and beta blocker, and propranolol (P), a nonselective beta blocker, were evaluated in a randomized, double-blind study of 35 hypertensive patients with echocardiographic evidence of LVH. Following 2 weeks of placebo, L or P was titrated as needed and tolerated to maximum total daily doses of 1600 mg and 640 mg, respectively. A thiazide diuretic was added if necessary for blood pressure control. M-mode echocardiograms were performed at baseline and after 1, 3, 6, and 12 months of blood pressure control. The echocardiograms were read independently by two blinded observers for end-diastolic dimension and wall thicknesses, and left ventricular mass. Fractional shortening, cardiac output, and peripheral vascular resistance were derived using standard formulas. Both drugs reduced blood pressure significantly and comparably. Significant changes in the echocardiographic measurements were observed as early as 1 month and usually persisted throughout the study. Both drugs decreased posterior wall thickness; however, only the decrease in propranolol group achieved statistical significance. Septal wall thickness was reduced by L at 3 and 12 months. End-diastolic dimension increased significantly in the L-treated group at 3, 6, and 12 months of therapy, whereas P had no effect on this measurement.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult

Effects of endothelin-1 in the isolated heart under ischemic and cardioplegic conditions.

We examined the effects of the vasoconstrictor peptide endothelin-1 in isolated hearts under ischemic and cardioplegic conditions. Isolated isovolumic rat hearts were perfused with Krebs-Henseleit buffer at constant pressure. Cumulative dose-response curves were obtained for endothelin-1 boluses of 0.04-400 pmol in four groups of hearts. Coronary flow decreased with increasing dosages and was almost abolished at 400 pmol in control hearts perfused at a constant pressure of 100 mm Hg. In hearts made ischemic by reducing coronary perfusion pressure to 35 mm Hg, thus reducing coronary flow by 76%, the constrictor effect of endothelin-1 was well preserved. The endothelin-1 dose-response curve was unaltered when hearts were perfused with buffer containing 30 mM KCl to abolish mechanical activity without reducing extracellular Ca2+ concentration. A fourth group of hearts was perfused with Ca2(+)-free buffer, thus eliminating the source of extracellular Ca2+ as well as mechanical activity. In this group, the constrictor response to endothelin-1 was largely, but not completely, abolished, with a maximal constrictor effect of only 19% as opposed to 87% in control hearts. We conclude that in isolated rat heart endothelin-1 is a potent coronary constrictor under ischemic perfusion conditions and that absence of mechanical activity does not affect the action of endothelin-1, for which the presence of extracellular Ca2+ is essential. The small residual constrictor response with Ca2(+)-free perfusion is probably due to release of Ca2+ from intracellular stores.

Animals

[Cost effectiveness of inpatient hospital care, day hospital care and outpatient consultation in pneumology. Apropos of 162 patients].

The authors report the results of a non-randomised study comparing the efficacy (in terms of confirmation of the diagnosis, the extent of disease, and measurements of airflow obstruction, and of the therapeutic index), and the efficiency in 58 patients suffering from lung cancer as well as 62 patients suffering from chronic airflow obstruction, and 42 asthmatics. These patients were seen in one of three possible services of a respiratory medicine department of a university hospital. The possibilities were inpatient stay in hospital, day hospital, or outpatient consultation. All the patients except one were totally independent, and could be taken into anyone of the three hospital services. The diagnostic efficacy for lung cancer was independent of the type of service used. The day hospital was four times more efficient than inpatient care for lung cancer, and consultation was 3.5 and 4.6 times more efficient than the day hospital for asthma and chronic airflow obstruction respectively. The balance of efficiency and the index of satisfaction experienced by the patients on the service used accentuated these differences.

Ambulatory Care

Opportunistic agents in bronchoalveolar lavage in 99 HIV seropositive patients.

During a ten month period, 117 fibreoptic bronchoscopies and bronchoalveolar lavages (BAL) were performed in human immunodeficiency virus (HIV) infected patients suspected of having opportunistic pulmonary infections. The BAL were classified into 3 groups, according to clinical manifestations related to HIV infection at the time of fibreoptic bronchoscopy: pre-acquired immunodeficiency syndrome (AIDS) (n = 54), AIDS with Kaposi's sarcoma (n = 37), AIDS without Kaposi's sarcoma (n = 26). On chest X-ray, diffuse infiltrates were most common (54%), followed by normal X-rays (24%) and localized infiltrates (18%). Amongst the 117 BAL, 68 (58%) yielded at least one opportunistic agent. In 28 BAL performed for pulmonary signs or unexplained fever with normal chest X-rays, one or several opportunistic agents were isolated in 17 samples of BAL fluid. The most frequently identified opportunistic agents were Pneumocystis carinii (in 38% of BAL) and cytomegalovirus (35%); these were associated in 17% of BAL. There was no statistically significant difference in opportunistic agents among the 3 groups of BAL (pre-AIDS, AIDS with Kaposi's sarcoma, AIDS without Kaposi's sarcoma). In particular, cytomegalovirus was found in BAL with the same frequency in these 3 groups.

Acquired Immunodeficiency Syndrome