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Biomedical subjects

I Hammer

Publications and source records attributed to I Hammer.

12 recordsLinked to original sources
PubMed2000

Urinary testosterone levels in the male blind mole rat (Spalax ehrenbergi) affect female preference.

This study investigated the sexual attraction of female blind mole rats to four groups of male mole rats: (a) intact males raised in captivity; (b) intact males trapped in the field; (c) captive males injected with testosterone; (d) captive castrated males. In the first part we measured blood testosterone, androstenedione, and dihydrotestosterone (DHT) levels, by radioimmunoassay; and urine testosterone levels, measured by GC-MS. The second part examined the relationship between urine testosterone levels in males and their attractiveness to females. Higher blood and urine testosterone levels were found in the field animals and in those injected with testosterone compared to captive intact or castrated animals: urine testosterone levels in the two other groups were not detectable. Blood androstenedione levels were also higher in the field animals and in those injected with testosterone compared to captive intact or castrated mole rats. Blood dihydrotestosterone levels were not detectable in all four experimental groups. Female mole rats chose to spend a longer period of time next to males with high blood and urine testosterone levels and high blood androstenedione levels than next to those with lower levels of these hormones. Because courtship and sexual behavior are influenced both by high levels of blood and urine testosterone and high levels of blood androstenedione, we suggest that the low levels of courtship and other sexual behavior in captive mole rats may be related to the lack of female attraction to these males, which display low levels of all three parameters.

Androstenedione↗
PubMed1989

[Cornu cutaneum].

We report on 62 cases of cornu cutaneum. In contrast to the general opinion that the majority of these lesions arise on the basis of an underlying actinic keratosis or a squamous cell carcinoma, on histological examination we found actinic keratoses in only 25% and squamous cell carcinomas in only 3.2% of cases; 58% of all lesions were identified as common warts. We therefore recommend removal of these skin lesions by the shaving technique followed by electrodesiccation of the base. This has the advantage of supplying the histopathologist with a representative specimen for histological examination and avoiding an unnecessarily large surgical excision. In the rare cases of histologically confirmed squamous cell carcinoma, these lesions can be excised in a second session.

Aged↗
PubMed1984

Tachycardia caused by an accessory nodoventricular tract: a clinico-pathologic correlation.

Paroxysmal tachycardia with widened QRS complexes was recorded in an eleven-year old boy who had suffered from brain damage, which had resulted from an episode of ventricular fibrillation. Atrial stimulation produced an increased AV conduction, sudden disappearance of the His bundle deflection and a complete left bundle branch block pattern. Tachycardias of this morphology were initiated by early atrial and ventricular premature beats. The findings suggested the presence of a macro re-entry circuit, utilizing a slow AV node- nodoventricular bypass tract as the anterograde limb and the His-Purkinje system--fast AV node as the retrograde limb. This supposition found further support by serial sectioning of the AV junctional area of the heart, which revealed a nodoventricular tract, which originated from the posterior extension of the compact part of the atrioventricular node and inserted into the crest of the ventricular septum.

Brain Damage, Chronic↗