Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.

Abstract: The efficacy of tympanometry in the diagnosis of ossicular abnormalities and the differentiation of such from eardrum scarring is controversial. This paper presents a study of the tympanometric effects of specific eardrum scars and ossicular abnormalities in cats. For both normal eardrums and healed myringotomies, a normal middle ear could be differentiated from stapes fixation or incudostapedial discontinuity using static immittance parameters and tympanogram morphology. Twenty percent myringectomy scars caused abnormal 660 Hz tympanograms but this effect could be distinguished from changes caused by a concomitant ossicular abnormality. The very low impedance of a 50% myringectomy scar resulted in tympanograms which could not be differentiated from an ossicular discontinuity alone. With this neomembrane, stapes fixation could not even be differentiated from an ossicular discontinuity. This study supports the view that tympanometry should be interpreted as part of a battery of tests which includes otoscopy, audiometry, and acoustic reflex measurements.
Effects of tympanic membrane scars on tympanometry: a study in cats.

Abstract: The split hydronephrotic kidney preparation was used to directly observe the effects of locally applied dopamine on the in vivo diameters of renal vessels. Dopamine (1 X 10(-6) to 3 X 10(-5) M) produced a concentration-dependent dilation of the arcuate and interlobular arteries and afferent arterioles. Efferent arterioles near the glomeruli also dilated to dopamine but the dilation was less than that of the preglomerular vessels. Higher dopamine concentrations (3 X 10(-4) and 1 X 10(-3) M) produced more variable effects, with a tendency for the arcuate and interlobular arteries and the afferent and efferent arterioles away from the glomeruli to decrease in diameter. After pretreatment with haloperidol, dopamine (1 X 10(-6) to 1 X 10(-4) M) did not dilate any pre- or postglomerular vascular segment, but the tendency for pre- and postglomerular constrictions with higher dopamine concentrations were not abolished. Pretreatment with phentolamine and propranolol enhanced the dilator response of the pre- and postglomerular vessels (except the afferent arterioles near glomeruli and efferent arterioles near welling points) to dopamine (3 X 10(-5) and 1 X 10(-4) M), and abolished the reductions in diameter produced by the high dopamine levels. These data indicate that the dilator effect of dopamine is mediated by interactions with specific dopaminergic receptors, while alpha and beta adrenergic receptors appear to mediate a constrictor influence observed with high dopamine concentrations. The overall effect of dopamine on the renal vessel diameters thus appears to depend on the balance of dilator and constrictor stimuli mediated by multiple receptors.
Responses of in vivo renal microvessels to dopamine.

Abstract: Aneurysms of the extracranial vertebral artery are rare because of the protection afforded by the bony canal, and the literature contains only a few limited reports on this subject. In the view of its rarity, we present the case of a 20-year-old soldier with a traumatic aneurysm of the vertebral artery at the C-2 level. Because of occlusion of the ipsilateral carotid artery, reconstruction of the vertebral artery by autogenous vein graft was undertaken through a posterior approach; because of inadequate mobilization of the artery, continuity was preserved using aneurysmorrhaphy. The literature is reviewed, and the various treatments are discussed.

Traumatic aneurysm of the extracranial vertebral artery.

