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Biomedical subjects

S Altan

Publications and source records attributed to S Altan.

7 recordsLinked to original sources
PubMed1999

Effect of investigator bias on the power and level of the two-sample Z-test.

The use of subjective measures in the evaluation of treatment efficacy in clinical trials may introduce bias into the response variables of interest when investigators attempt to guess the treatment that patients are receiving. The bias may be introduced even in the setting of double-blind clinical trials due to the presence of characteristic side effects. The introduction of bias leads to an increase in the power of the statistical test. However, this increase in power is achieved at a considerable increase in the actual level of the statistical test.

Double-Blind Method↗
PubMed1998

The analysis of small-sample multivariate data.

Clinical pharmacology studies typically consist of few subjects per treatment group, but with many, possibly highly correlated, measurements taken per subject. Permutational methods for testing equality of the multivariate treatment means when the number of variables exceeds the number of independent subjects have been developed, but are highly computationally intensive. In this paper, a parametric test was derived, using Edgeworth expansions, for the case of two groups, and compared with competing test statistics proposed by Mercante and Johnson (7), Dempster (5), Chung and Fraser (3), Mantel and Valand (6). The proposed test compares favorably with the others in terms of type I error rate, as well as power, and has the advantages of not requiring computationally intensive resources and being easily extendable to more than two groups.

Clinical Trials as Topic↗
PubMed1995

Anophthalmos-syndactyly (Waardenburg) syndrome without oligodactyly of toes.

We report on 2 brothers from a consanguineous family from a small city of southeast Turkey. Both have bilateral anophthalmia, soft tissue syndactyly of the feet, bilateral partial synostosis of metatarsals IV and V, and basal synostosis of the fourth and fifth toes on the right in the older sib only, thus differing from all previously reported cases of anophthalmos-syndactyly syndrome.

Child↗
PubMed1977

Lung cancer type in relation to cigarette dosage.

In a retrospective study of 1,228 white males with histologically confirmed bronchogenic carcinoma, the proportion of squamous cell carcinoma increased with increasing age at diagnosis. Since the distribution of cell types was much the same in the 73% of cases aged 50-69, the relationship of cancer type to daily cigarette dosage was studied in this group. Squamous cell carcinoma increased from 48% of those men who smoked less than 20 cigarettes per day to 61% of those who smoked 40 or more cigarettes per day. Comparison with other studies showed conflicting results.

Adenocarcinoma↗
PubMedDate not supplied

Developmental effects of phenytoin may differ depending on sex of offspring.

Phenytoin (sodium salt), a developmental neurotoxicant, was administered orally by gavage (50-150 mg/kg) to pregnant rats on days 7-18 of gestation. Various developmental and behavioral indices were evaluated. Results indicated that phenytoin produced decreases in maternal and pup body weight gains, pup hindbrain, and F1 adult forebrain, whole brain, and cerebellar weights. Behavioral/developmental effects included performance deficits in a modified Morris water maze assay, in air righting and auditory startle responses, and increases in locomotor activity, accelerated eye opening, incisor eruption, negative geotaxis, and olfactory orientation. Female offspring appeared to be more severely affected when measuring incisor eruption, negative geotaxis, air righting, reactivity, and locomotor and maze activity. Males appeared to be more affected when measuring eye opening, olfactory orientation, and decreases in startle response. This study suggests that prenatal phenytoin exposure may result in developmental changes and behavioral deficits that may differ depending on the sex of the offspring.

Animals↗
PubMedDate not supplied

Color Doppler ultrasound in ocular Behçet's disease.

The purpose of this study was to evaluate the hemodynamic changes occurring in the ophthalmic vasculature of eyes with Behçet's disease in a controlled clinical trial. Both eyes of patients with retinal involvement due to Behçet's disease were consecutively evaluated and were established as having mild or severe retinal vasculitis according to the ophthalmoscopic and fundus fluorescein angiographic findings. One eye from each patient was randomly selected and 25 eyes with mild to moderate and 25 eyes with severe vasculitis were identified. Color Doppler imaging (CDI) was used to quantitate blood flow velocities and vascular resistance in the ophthalmic artery (OA), central retinal artery (CRA) and central retinal vein (CRV) of these patients and those of 25 healthy volunteers. All three groups were age- and sex-matched. In the OA, peak systolic, end diastolic and average flow velocities were significantly higher in patients with Behçet's disease than in the control group (p < 0.05). CRA blood flow velocities of patients with severe retinal involvement were significantly lower than those with mild to moderate vasculitis and control groups and the average vascular resistance was significantly higher than in the control group (p < 0.05). Additionally, the average blood flow velocities in the CRV of patients with severe vasculitis were significantly lower than in mild to moderate vasculitis and control patients. Marked circulatory changes were seen in the ophthalmic vasculature of eyes with Behçet's disease. Although larger studies are required to define the true sensitivity and specificity of this technique, these initial results suggest that CDI could play a major part in the assessment of patients with ocular Behçet's disease.

Adult↗