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Biomedical subjects

D R Knapp

Publications and source records attributed to D R Knapp.

At least 73 records · Page 4Linked to original sources
PubMed1980

Drip infusion cholangiography using iotroxamide. Double blind comparison with ioglycamide.

A double blind clinical trial was carried out in 200 unselected patients to compare the efficacy and tolerance of ioglycamide and iotroxamide as contrast media for intravenous cholangiography. The two agents were administered by slow infusion at a rate of 2.6 mumoles/kg bodyweight/minute for one hour. Radiological opacification of the bile duct was assessed independently by two radiologists. In patients with serum bilirubin levels of less than 34 mumoles/litre visualization of the bile duct was significantly better with iotroxamide than with ioglycamide (P < 0.001). Toxic side effects were observed in 8% of patients receiving ioglycamide and in only 3% of the patients given iotroxamide.

Adult↗
PubMed1979

Maternal, fetal, and neonatal metabolism of lidocaine.

We investigated the metabolism of lidocaine to its active metabolites--monoethylglycinexylidide (MEGX) and glycinexylidide (GX)--in the mother, fetus, and neonate. The study population included normal patients and their infants delivered either vaginally or by cesarean section. A group of infants of mothers in whom pudendal anesthesia was induced was also included. Using gas chromatography and mass spectrometry techniques, the concentrations of lidocaine, MEGX, and GX were determined in maternal plasma during labor, in umbilical cord venous and arterial plasma at delivery, and in maternal and neonatal urine for 3 days post partum. The results indicate the following: In maternal plasma, MEGX rises throughout labor and GX is usually detectable within an hour of medication; in cord blood plasma the levels of lidocaine, MEGX, and GX suggest fetal metabolism of lidocaine; and in neonatal urine, the relative levels of parent compound and metabolites confirm lidocaine metabolism by the neonate.

Adolescent↗
PubMed1979

The effects of alpha adrenergic agents on human platelet aggregation.

The effects of alpha adrenergic agonists and antagonists on human in vitro platelet aggregation were studied to characterize further the platelet alpha adrenergic receptor. Aggregation induced by ADP and U46619; a stable prostaglandin endoperoxide analog, was potentiated by alpha adrenergic agonists, an effect which was completely blocked by the alpha adrenergic antagonist phentolamine (1 X 10(-6) M) but not by prazosin (1 X 10(-6) M). The order of potency for the alpha adrenergic agonists in potentiating ADP-induced aggregation was clonidine greater than or equal to epinephrine greater than alpha-methylnorepinephrine greater than norepinephrine greater than phenylephrine greater than methoxamine. Epinephrine-induced platelet aggregation was blocked by phentolamine, yohimbine, dihydroergotamine, clonidine and lofexidine but not by phenoxybenzamine (1 X 10(-5) M). These findings suggest that: 1)clonidine and lofexidine are partial agonists and 2) that the alpha adrenergic receptor of the platelet is different from the classical postsynaptic alpha adrenergic receptor and more closely resembles presynaptic alpha adrenergic receptors.

Adenosine Diphosphate↗
PubMed1978

Formation of catechol-like and monophenolic metabolites of propranolol by the rat liver 9000G supernatant.

The oxidation of the naphthalene ring system of propranolol by the rat liver 9000g supernatant has been studied by gas chromatography-mass spectrometry. Two dihydroxy metabolites, one of which possibly catechol-like, and four monophenols were identified based on the mass fragmentation pattern and retention times of their trimethylsilyl and d9-trimethylsilyl derivatives. These observations emphasize the complex oxidation pattern of this drug. All metabolites identified are proposed to be associated with significant biological activity.

Animals↗
PubMed1973

Treatment of chronic gastric ulcer with carbenoxolone and gefarnate: a comparative trial.

In 68 patients with chronic gastric ulcer treated in an outpatient clinical trial with either carbenoxolone or gefarnate ulcer healing was consistently greater during carbenoxolone treatment, even though the dose of gefarnate was ultimately increased to four times that recommended. One-third of the patients receiving carbenoxolone gained weight rapidly and unexpectedly, and were given diuretic treatment, compared with two of the 35 patients receiving gefarnate, neither of whom developed clinical oedema.

Body Weight↗