Biomedical subjects

S Francis

Publications and source records attributed to S Francis.

57 records · Page 4Linked to original sources

PubMedDate not supplied

Tyrosine-612 in PDE5 contributes to higher affinity for vardenafil over sildenafil.

Despite close structural similarity, vardenafil (Levitra) is 32-fold more potent than sildenafil (Viagra) to inhibit cGMP-binding cGMP-specific PDE (PDE5); this is due to differences between their heterocyclic rings. In co-crystals with PDE5, one of the rings of vardenafil or sildenafil interacts with Tyr(612), a catalytic site AA, via (1) a hydrogen bond with a water molecule and (2) hydrophobic bonds. For mutant PDE5(Y612F), which ablates hydrogen-bonding potential, vardenafil or sildenafil inhibition was strengthened (2.2- or 3.0-fold, respectively), implying that the Tyr(612) hydroxyl is a negative determinant for these inhibitors. For mutant PDE5(Y612A), which ablates both hydrogen bonding and hydrophobic-bonding potential, vardenafil inhibition was weakened much more than sildenafil inhibition (122- and 26-fold, respectively), suggesting that hydrophobic bonds involving Tyr(612) are stronger for vardenafil than for sildenafil.

1-Methyl-3-isobutylxanthine↗

PubMedDate not supplied

Running a nurse-led nebulizer clinic in a district general hospital.

The widespread home use of nebulizers for delivering bronchodilating medication in patients with a variety of respiratory conditions is well documented, as is the lack of appropriate assessment before this form of treatment is prescribed (Cochrane et al, 1985). When it is considered that the use of nebulizers at home is increasing (Drug Information Bulletin, 1994), it is essential that appropriate assessment is undertaken in line with British Thoracic Society recommendations in order to ensure that the degree of benefit is sufficient to justify the inconvenience, potential dangers and high cost of nebulizer therapy in the home. This article examines a nurse-led nebulizer assessment clinic that was set up as part of a service for providing home nebulization for long-term use in patients with chronic obstructive pulmonary disease or chronic severe asthma.

Administration, Inhalation↗

PubMedDate not supplied

The zymodemes of Entamoeba histolytica in New Delhi, India.

The prevalence of various pathogenic and non-pathogenic zymodemes of Entamoeba histolytica in New Delhi, India was studied by characterising its isoenzyme patterns. Non-pathogenic zymodeme I was found to be most common and was detected in 39 of 49 infections. The other non-pathogenic zymodemes detected were XVII and XVIII in two cases each. The pathogenic zymodemes detected were II (four cases), II alpha- (alpha) (one case) and XIV (one case). Approximately 72% of those harbouring non-pathogenic zymodemes and 33% of those harbouring pathogenic zymodemes were asymptomatic. All the symptomatic individuals harbouring non-pathogenic zymodemes were seronegative for amoebiasis. However, subjects harbouring pathogenic zymodeme but asymptomatic were seropositive for amoebiasis at a titre of greater than 1:80, indicating a past infection or subclinical tissue invasion by the parasite. The new zymodeme isolated from a case of acute dysentery was designated II alpha- on the basis of the banding pattern of the enzyme glucose phosphate isomerase.

Amebiasis↗