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Biomedical subjects

L Sandvik

Publications and source records attributed to L Sandvik.

85 records · Page 5Linked to original sources
PubMed1986

The width of the light reflex on retinal arteries and veins.

A computerized microdensitometric technique was applied to fundus photographs of 40 young male subjects. The width of the blood column and the width of the central light reflex were measured on 240 arteries and 240 veins of various sizes. No light streaks were registered on vessels of caliber less than 50 micron. The ratio of the widths: light streak/blood column showed wider reflexes on small (less than 100 micron) compared to larger (greater than or equal to 100 micron) vessels in both arteries and veins (P less than 0.01). Small retinal veins had wider light streaks than small arteries (P less than 0.01). The results of these objective measurements are partly in conflict with previous ophthalmoscopic observations, and we challenge accepted views on clinical interpretation on reflectivity differences in normal retinal vessels. Our results are discussed on a background of hemodynamics of microcirculatory flow.

Adult↗
PubMed1986

The intensity of the light reflex on retinal arteries and veins.

The intensity profiles of the central light streak on various sized retinal vessels were measured by a computerized high quality scanning microphotometer. From the fundus photographs in 40 young men 240 arteries and 240 veins were analysed, and light streaks were found on 171 arterial and 170 venous sites. Differences in reflected intensities between arteries and veins and between small and large vessels were studied. In the whole range of vessels measured (50-200 microns) significantly higher intensities were found on arteries compared to veins (P less than 0.01). Large vessels (100-200 microns) reflected the light more intensely than small vessels (50-99 microns) (P less than 0.001). Variations in haemodynamics of flow and in physical properties of the streaming erythrocytes might account for the reflectivity differences between arteries and veins.

Adult↗
PubMed1985

Effects of intensified insulin treatment on various lesions of diabetic retinopathy.

Mild background retinopathy was studied prospectively during long-term strict blood glucose control in insulin-dependent diabetes mellitus. Forty-five subjects (21 women and 24 men with a mean age of 26.3 years and a mean duration of diabetes of 12.8 years) were randomly assigned to continuous subcutaneous insulin infusion, multiple injections, and conventional two-injection treatment. Eyes were examined two months before treatment, at the beginning of treatment, and after three, six, and 12 months. A progressive deterioration was found in the two-injection group during the study, but no significant changes were found in patients receiving multiple injections. A transient deterioration occurred after three months of continuous subcutaneous insulin infusion. Soft exudates appeared in 50% of the patients on the two intensified regimens, but no exudates were found in patients given conventional treatment. The morphologic changes seemed to be related to a large and rapid decrease in mean blood glucose or to an increased frequency of hypoglycemia, or both.

Adolescent↗
PubMed1985

Rapid tightening of blood glucose control leads to transient deterioration of retinopathy in insulin dependent diabetes mellitus: the Oslo study.

In a study of retinopathy during one year of tight blood glucose control 45 type I (insulin dependent) diabetics without proliferative retinopathy were randomised to receive either continuous subcutaneous insulin infusion, multiple insulin injections, or conventional insulin treatment (controls). Near normoglycaemia was achieved with continuous infusion and multiple injections but not with conventional treatment. Blind evaluation of fluorescein angiograms performed three monthly showed progression of retinopathy in the control group, transient deterioration in the continuous infusion group, and no change in the multiple injection group. Half the patients receiving continuous infusion and multiple injections developed retinal cotton wool spots after three to six months. These changes regressed in all but four patients after 12 months. Control patients did not develop cotton wool spots. Patients who developed cotton wool spots are characterised by a larger decrement in glycosylated haemoglobin and blood glucose values, more frequent episodes of hypoglycaemia, a longer duration of diabetes, and more severe retinopathy at onset. A large and rapid fall in blood glucose concentration may promote transient deterioration of diabetic retinopathy.

Adolescent↗
PubMed1985

The effect of cimetidine in non-ulcer dyspepsia. Experience with a multi-cross-over model.

The symptomatic effect of cimetidine was examined in 27 patients with non-ulcer dyspepsia (NUD) by means of a multi-cross-over model (MCO model) for testing the symptomatic effect of drugs in individual patients. None of the patients showed an ulcer at the time, but 20 patients had evidence of previous peptic ulcer disease. The variant of the MCO model used included six treatment periods and three regular interchanges between cimetidine and placebo. Treatment periods lasted 2 or 4 days. The individual results were evaluated on the basis of the number of times (X score) cimetidine was associated with less symptoms than the preceding or following placebo. In general, cimetidine was associated with significantly (p less than 0.02) less symptoms than placebo. The X-score distribution was therefore skew in favour of high scores. Five patients showed the maximal X score of 5. The chance of getting an X score of 5 when cimetidine is not better than placebo is about 9%. Accordingly, the risk of being wrong when defining these five patients as cimetidine responders is 9%. The present study confirms that the MCO model may identify individual cimetidine responders among patients with NUD.

Adult↗
PubMed1985

Factors influencing the sample size, exemplified by studies on gastroduodenal tolerability of drugs.

The necessary number of subjects to be included in a clinical trial depends on different factors. Exemplified by clinical trials on gastroduodenal tolerability of NSAID, we show how the sample size increases when the significance level decreases, the detection level increases, or the clinically relevant difference decreases. The sample size also increases when the trial design is changed from a cross-over to a parallel-group design. It is concluded from an ethical and statistical point of view that the sample size must be calculated when planning a study.

Clinical Trials as Topic↗
PubMed1985

Controlled trials in gastrodyspepsia: a methodological aspect.

Non-ulcer dyspepsia (NUD) is a poorly defined condition that is not very suitable for conventional randomised double-blind studies. A multi cross-over model (MCO-model) has been designed allowing identification of individual drug responders with a defined degree of certainty. The model involves regular interchanges between periods with active drug and placebo, and the evaluation is based on the number of times the active drug is associated with fewer symptoms than the preceding or following placebo period (X-score). A drug responder may be defined by a certain minimum value for the X-score. The risk of being wrong may then be easily calculated from the probability distribution of the X-score. The effect of cimetidine in patients with NUD has been studied using a variant of the MCO-model including 6 treatment periods of 2 or 4 days' duration. So far, the conclusion that the MCO-model is able to identify individual cimetidine responders among patients with NUD appears to be justified. The preliminary findings furthermore suggest that cimetidine responders among patients with NUD are characterised rather by symptoms suggestive of reflux esophagitis than by hypersecretion of acid.

Cimetidine↗
PubMed1984

Transdermal scopolamine, oral meclizine, and placebo in motion sickness.

The efficacy of transdermal scopolamine, oral meclizine, and placebo in protection against motion sickness was compared in a double-blind crossover study. Thirty-six healthy subjects were exposed to motion three times for 90 min in a ship-motion simulator. Transdermal applications were made and tablets were taken at least 12 and 2 hr before exposure to motion. Transdermal scopolamine provided better protection than placebo or meclizine. Dryness of mouth was the only side effect reported more frequently for one regimen, transdermal scopolamine.

Administration, Oral↗
PubMed1983

Clinical effects of hyposensitization using a purified allergen preparation from Timothy pollen as compared to crude aqueous extracts from Timothy pollen and a four-grass pollen mixture respectively.

Most extracts used in hyposensitization are complex and ill-defined mixtures of a large number of antigenic components. A highly refined (purified) and well-characterized allergen preparation from Timothy pollen (Phleum pratense) is now available. This paper describes the results of hyposensitization for 3 years comparing the purified preparation Timothy N, the crude extract Timothy O and a four-grass mix in sixty patients with allergic rhinitis due to grass pollen. The sixty patients were randomized into three groups and compared with a control group not hyposensitized. All three groups showed a significant decrease in clinical symptoms compared with the control group. The Timothy N group had a significantly higher nasal tolerance shown by nasal challenge test after 3 years' treatment than the group treated with the crude extract (P = 0.05). In addition, the Timothy-N-treated patients needed significantly less antihistaminic medication than the patients having received the crude extract or the four-grass mix (P = 0.02 and P = 0.01, respectively).

Adult↗
PubMed1980

Hyposensitization. Comparing a purified (refined) allergen preparation and a crude aqueous extract from timothy pollen.

Most extracts used in hyposensitization (immunotherapy) are complex and ill-defined mixtures of a large number of non-antigenic and antigenic components, only a few of the latter being of significance for allergy and allergen specific immunotherapy. A new purified and well-characterized allergen preparation from timothy pollen is now available, and it has been shown to be superior to the corresponding crude aqueous extract in the diagnosis of IgE-mediated human allergy to timothy pollen. This paper describes the results of hyposensitization for 2 years, with the purified preparation and the crude extract compared. The changes in in vivo and in vitro tests following this treatment in 40 patients with allergic rhinitis due to grass pollen are reported. Both patient groups showed a significant decrease in clinical symptom scores when compared with a control group during the grass pollen season. For all groups the symptom scores correlated well with atmospheric pollen counts. Nasal challenge tests showed a significant increase in nasal tolerance to timothy pollen after 2 years of treatment, but nasal tolerance was unchanged in the control group. Nasal function as a criterion for evaluating the effect of specific hyposensitization is discussed. Serum concentrations of timothy pollen-specific IgE antibodies showed a significant decrease for the group treated with the purified preparation and a slighter and non-significant reduction for the other treated group. There was no significant change in total serum IgE levels. The results indicate that the purified preparation is preferable to the crude aqueous extract in hyposensitization.

Adult↗