Search PubMed⌕ Search

Biomedical subjects

R Webster

Publications and source records attributed to R Webster.

At least 55 records · Page 3Linked to original sources

Sublingual apomorphine in the treatment of Parkinson's disease complicated by motor fluctuations.

Subcutaneous apomorphine is a useful treatment for refractory motor fluctuations in Parkinson's disease. We have now clinically evaluated a formulation of sublingual apomorphine (57 mg) and performed preliminary pharmacokinetic studies. In acute studies, all 10 patients switched "on" after a mean latency of 25 min with a mean duration of motor benefit of 118 min. In three patients followed for a mean of 4.7 months, we have shown that chronic sublingual use can be effective, safe, and convenient in controlling motor fluctuations. The pattern of clinical response followed closely the plasma profile of apomorphine with a mean Cmax of 76 pmol/ml (50-106 pmol/ml) and a mean Tmax of 60 min (45-80 min), with moderate interpatient variability in bioavailability. Sublingual apomorphine is a practical alternative to subcutaneous use in selected patients with severe motor fluctuations.

Administration, Sublingual↗

Separation of the enantiomeric intermediates of some platelet-activating factor analogues on a naphthylalanine-type Pirkle column.

A chiral high-performance liquid-chromatographic separation method was developed for the analysis of some glycerol-based, ether-linked platelet-activating factor precursors. Using a D-naphthylalanine-type Pirkle-column and tetrahydrofuran-hexane eluents, the retention-structure relationships were determined for a large number of glycerol ether derivatives. The derivatives leading to the highest chiral selectivity factors in the analytical separations were surveyed for their applicability in large-scale isolation of chiral synthetic intermediates.

Alanine↗

Diurnal differences in response to oral levodopa.

Diurnal differences in duration and quality of motor response to levodopa are frequently described by patients. The quality and duration of motor responses were objectively assessed to morning and afternoon oral levodopa doses in five patients with Parkinsonian motor fluctuations who complained of diurnal variation in response to their normal levodopa medication. Results suggest that under controlled conditions which eliminated the effects of diet and overlapping levodopa effects the response to levodopa remained unchanged throughout the day, and that the duration of response could be predicted by plasma levodopa levels.

Administration, Oral↗

Spatial distribution on pasture of infective larvae of the gastro-intestinal nematode parasites of sheep.

The horizontal distributions of infective larvae on pasture grazed by sheep have been investigated. Using Taylor's Power Law it was found that larvae had a more aggregated distribution in September than August, the Law index of aggregation being 1.97 and 1.89 for the 2 months, respectively. However, at each time the degree of aggregation remained fairly constant for a range of spacings between points from 5 to 30 m. These results suggest that Taylor's Power Law could be used as a basis for devising an efficient pasture sampling strategy. More data are required, however, to determine the extent to which aggregation of the larvae varies with time of the year.

Analysis of Variance↗

Levodopa peripheral pharmacokinetics and duration of motor response in Parkinson's disease.

To assess the relative influence of central pharmacodynamic and peripheral pharmacokinetic factors on the duration of motor response to levodopa, the relationship between motor function and plasma levodopa levels was studied in 31 Parkinsonian patients. Duration of benefit from single levodopa doses while fasting depended on the degree to which the plasma levodopa level had declined over four hours; wearing off occurred when the plasma levodopa level had fallen to approximately 50% of peak concentration, irrespective of the duration of the motor response. Whilst the amplitude of motor response to levodopa is likely to be modified by alternations in dopamine receptor stimulation and sensitivity as the disease progresses, it is proposed that the duration of response is primarily determined by levodopa peripheral pharmacokinetics rather than by central pharmacodynamic factors associated with dopamine storage capacity.

Administration, Oral↗

The effects of oral protein on the absorption of intraduodenal levodopa and motor performance.

Four patients with levodopa induced fluctuations in motor performance were studied during the constant intraduodenal infusion of levodopa. The results confirm that steady plasma levodopa levels with stable motor control can be achieved. However, when patients were given oral protein loads, motor performance declined despite maintenance of plasma levodopa levels. These findings suggest that competition for levodopa carrier mediated transport by amino acids, is more important at the blood-brain barrier than across the gut mucosa; thereby possibly limiting the efficacy of long-term direct intraduodenal administration of levodopa.

Aged↗

Child-environment relationships: a cross-cultural study of educable mentally retarded children and their families.

A cross-cultural study was conducted to determine the generality of child-environment relationships in Japanese and American families with educable mentally retarded (EMR) children. A total of 90 families with EMR children in Japan and 93 families with EMR children in America participated. The Henderson Environment Learning and Process Scale, Family Environment Scale, and Home Quality Rating Scale were employed in home interviews and observations. The AAMD Adaptive Behavior Scale was used to measure social competency and psychosocial adjustment of the children. The results indicated that the relation between cognitive opportunities at home and the child's social competency appeared similar between the two cultures. However, the relation between the affective aspects of home environment and the child's psychosocial adjustment appeared to differ between the two cultures.

Activities of Daily Living↗

Supramid tip implants in rhinoplasty. Review of 98 cases.

The nasal tip procedure is the most sophisticated aspect of a rhinoplasty, particularly in certain known problem types of nasal tips. A new approach, using Supramid tip implants, is introduced. Precise guidelines for the preoperative planning and operative techniques are developed, and the so-called pocket, experience, positioning, shape and size, and incision (PEPSI) rule is outlined. A comparative discussion of the advantages and disadvantages of the Supramid implant vs cartilage grafts and/or repositioning of alar cartilages is presented. The Supramid implant was used in the tip area for nasal tip alteration in a total of 98 cases. Patients were monitored for a period of six months to four years. The results were satisfactory.

Female↗

Effects of lobar pulmonary blood flow on the evolution of oleic acid lung injury in dogs.

We studied the effects of interruption of the pulmonary blood flow to the left diaphragmatic lung lobe on the evolution of canine oleic acid lung injury. We compared the morphology and edema of the left diaphragmatic lobe, whose pulmonary artery was ligated immediately after oleic acid injury, with the right diaphragmatic lobe, in which the blood supply was intact. The injury plus ligation resulted in hypoxemia and pulmonary hypertension with PaO2 falling from 98 +/- 4 to 72 +/- 21 torr (P less than 0.05) and pulmonary artery pressure increasing from 11 +/- 3 to 18 +/- 4 mm Hg (P less than 0.05). Animals were sacrificed 48 hr following the injury. Morphological examination of right and left lobes showed no consistent differences although wet/dry ratios indicated significantly greater edema (P less than 0.01) for the right diaphragmatic lobes (7.66 +/- 1.23) than the left (6.80 +/- 0.59). Both right and left lobes were substantially more edematous than our laboratory normal value of 4.74 +/- 0.54 (P less than 0.001 for both). We conclude that interruption of pulmonary arterial blood flow protects against edema formation in oleic acid injury but does not alter the morphologic evolution of the injury.

Animals↗

Mental rehearsal of a task under ethanol facilitates tolerance.

Male social drinkers learned a motor-skill task and then drank the same dose of ethanol (0.66 g/kg) on five sessions. Sessions 1 and 5 provided pre- and post-treatment measures of performance under ethanol. During treatment sessions, one group (P) practiced and another (M) mentally rehearsed the task after ethanol was administered. A control group (C) rested. On the posttreatment session, groups P and M did not differ and both were less impaired (i.e., more tolerant) than C. These results suggest that the development of ethanol tolerance is sensitive to the same training procedures which facilitate drug-free learning of a task.

Adult↗

Simple staining of bacteria and fungi in hide, skin and leather.

Enhanced detection of bacteria and fungi in raw skin and in skin from the various processing stages in leather production was achieved with a new staining procedure. A combination of cresyl violet and azure A is recommended in conjunction with Young's periodic acid-Schiff's reagent.

Animals↗

Effect of monoclonal anti-neuraminidase antibodies on the kinetic behavior of influenza virus neuraminidase.

Neuraminidase from the recombinant influenza virus A/NWSHA-Tokyo/3/67NA HON2 has been shown to exhibit non-Michaelis-Menten kinetics. The multiphasic behaviour was demonstrated for both the isolated neuraminidase heads and for the intact virus. Interaction of the enzyme with two monoclonal anti-neuraminidase antibodies (WANA 1 and RANA 1), which recognize separate antigenic determinants on the molecule, resulted in hyperbolic kinetic behaviour. While both antibodies abolished the multiphasic kinetics of the enzymic reaction, only WANA 1 altered the Vmax and Km values, indicating that it may in some way inhibit the interaction of enzyme and substrate.

Antibodies, Monoclonal↗

Antigenic structure of influenza virus haemagglutinin defined by hybridoma antibodies.

The recurrence of influenza virus infection in man is attributed primarily to changes occurring in the antigenic structure of the viral surface glycoproteins, especially of the haemagglutinin (HA) molecule. Comparative antigenic analysis of epidemic influenza virus strains has allowed the description of 'strain-specific' and 'cross-reactive' antigenic determinants. However, the interpretation of these findings remained ambiguous, because the specificity of the applied antisera was insufficiently defined and because the antigenic differences among the HA molecules of various epidemic virus strains resulted presumably from a large number of amino acid substitutions. Thus, in characterizing the antigenic structure of the HA molecule, our approach has been (1) to generate a panel of monoclonal anti-HA hybridoma antibodies, (2) to use some of these antibodies to select mutants of the influenza A/PR/8/34 (PR8) virus expressing antigenically altered HA molecules, and (3) to construct an operational antigenic map of the HA molecule by comparative antigenic analysis of the mutant viruses with the monoclonal antibodies. As we report here, analysis of the 34 mutant viruses selected has enabled us to define four antigenic sites on the HA molecule. Our observation that these sites have undergone antigenic drift to a different extent in nature implies that the mechanisms responsible for antigenic drift act selectively on distinct structures of the HA molecule.

Animals↗