Gender differences in cochlear response time: an explanation for gender amplitude differences in the unmasked auditory brain-stem response

Derived narrow-band auditory brain-stem responses (ABRs) in young normal-hearing subjects revealed a significant gender difference in response time between frequency regions of the cochlea. Females showed shorter delays than males between derived bands. This differential has not been previously reported. As in many early studies, the unmasked amplitude of the wave V complex was significantly larger (30%) in females than males. However, differences in amplitudes of the narrow-band responses were too small to account for the differential in the unmasked response. It is hypothesized that the larger amplitude of the unmasked wave V complex in females occurs because of a faster response time across the cochlea leading to better neural synchrony and, therefore, larger amplitudes. Furthermore, results can be explained by assuming that the stiffness gradient in the cochlea is 13% larger in females than in males. If males and females have the same cochlear tonotopic mapping, the female cochlea should be 13% shorter. This prediction is highly consistent with recent anatomical studies of cochlear length and gender. The results of the present study indicated possibly important cochlear mechanisms that influence the main parameters of ABRs. An understanding of these cochlear mechanisms may improve the diagnostic capabilities of ABRs in patients with peripheral hearing loss.     

Prostaglandin E2 stimulates ion transport in prairie dog gallbladder

The effects of progesterone and RU486, a synthetic anti-progesterone, on ovarian 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) activity, a key enzyme of progesterone production, were studied during ovulation in immature 22-day-old rats primed with pregnant mares' serum gonadotrophin (PMSG) and human chorionic gonadotrophin (hCG). Ovarian 3 beta-HSD activities had increased significantly 4 h after hCG injection. These increases were inhibited at 4 and 6 h after hCG when 20 mg RU486 kg-1 was administered 2 h before hCG. However, RU486 had no influence on the activity of 3 beta-HSD when administered at the same time as hCG injection. A histochemical study revealed that 3 beta-HSD activities in the granulosa cell layer, but not in the theca cell layer, were inhibited when RU486 was given 2 h before hCG. Serum progesterone concentrations, but not oestradiol concentrations, were significantly suppressed by RU486 treatment 4 and 6 h after hCG. The effect of progesterone on ovarian 3 beta-HSD activity was tested by administering graded doses of progesterone exogenously to rats 2 h before hCG injection. Ovarian 3 beta-HSD activity was increased in a dose-dependent manner, and more than 20 mg progesterone kg-1 significantly stimulated the activity. Although 10 mg progesterone kg-1 did not stimulate ovarian 3 beta-HSD activities, the RU486-inhibited activities were recovered by the concomitant administration of 10 mg progesterone kg-1 with RU486. These results indicate that ovarian 3 beta-HSD activity depends on progesterone concentrations, and suggest an autocrine regulation of progesterone production during ovulation in immature rat ovaries stimulated with PMSG and hCG.     

Mass transfer in a stirred transfer cell with a flat interface

A agitated vessel of Lewis cell type was used to investigate the effect of physical properties on the mass transfer coefficient for partially miscible binary systems. Some measurements were performed with ternary systems transferring only one solute across two immiscible solvents. The mass transfer coefficients were measured under the conventional contra-rotating conditions which were behaved as if the interface was not rotating for some combinations of agitation speeds in each of the two phases. The mass transfer coefficient was deduced from solving a steady-state two dimensional convective-diffusion equation with the assumption of sinusoidal motion of eddies. Owing to the complexity of the hydrodynamic conditions near the liquid-liquid interface, theoretical approach was impossible. Thus, the effects of forced turbulence and physical properlies on the effective surface renewal time were experimentally investigated. The relation between the mass transfer coefficients and the relevant variables was obtained by conventional dimensional analysis as follow: 1 $$Sh_w = 1.93 \times 10^{ - 3} Ca^{1/2} Sc_w^{0.5} Re_w^{0.70} exp(1.60 \times 10^{ - 4} \frac{{v_w }}{{v_o }}Re_o )$$      

The plasma protein binding and distribution of etomidate in dog, rat and human blood

The interactions of etomidate and its major metabolite (R 28 141) with plasma proteins were studied by equilibrium dialysis with a multiple cell system. A 4% human serum albumin solution was able to bind 78.5% of the etomidate, and 60.5% of R 25 141, whereas a 1.5% human gamma globulin solution bound etomidate for not more than 3% and did not bind R 28 141 at all. The association constants and free binding energies for the binding of etomidate and R 28 141 to human serum albumin were determined. Plasma protein binding of etomidate was 75.4% in the dog and 76.5% in man; in rat plasma 79.5% of the radioactivity was bound to the plasma proteins, however the etomidate was partly hydrolyzed, even in the presence of sodium fluoride. In the rat 29.7% was distributed to the blood cells, 55.9% bound to plasma proteins and 14.4% was present in plasma water; in the dog the distribution percentages were 42.1%, 43.7% and 14.2% respectively, and in man 37.7%, 47.6% and 14.7% respectively. The major metabolite of etomidate was distributed for 26.3% to the human blood cells, 47.4% was bound to plasma proteins and 26.2% was present in the plasma water; its plasma protein binding amounted to 64.3%. Etomidate was bound at or in the blood cells, whereas R 28 141 was not.     

Reversal by naloxone of the effects of morphine on the unanesthetized dog]

In unasthetized dogs naloxone induced effects opposed to those of morphine (tachycardia, agitation, hyperthermia, tachypnea) and mydriasis. These effects were moderate and transient; some of them were elicited with low doses being border-line after 0.03 mg.kg-1 s.c., statistically significant after 0.1 mg.kg-1 s.c.; they increased slightly with the dose. After repeated administrations, acute tolerance developed and some moderate morphine-like effects (miosis, sedation) were observed. The stimulatory effects described here may result from antagonism of a morphinomimetic natural ligand,and represent thus indirect arguments in favour of normal functions of this ligand; these functions would be to temper not only algesic but also other stimulant reactions. The limitation of the effects might result from the limited release of this ligand in normal dogs and (or) from interfering morphinomimetic properties of naloxone, which are apparently unmasked when administrations are repeated. Both, stimulatory and inhibitory effects of naloxone are not liable to represent noticeable side-effects of this drug, but they both might play some role in the mechanisms of precipitated abstinence.     

Continuous dynamic monitoring of pressure and flow patterns during assisted ventilation

On curettage, done in a 39 year old patient because of metorrhagia, a peanut-sized nodule was scraped away from the endometrium. Histologically it consisted of a jumble of irregularly shaped portions of normal appearing embryonal cartilage, of tortuous thick-walled vessels, of twisted bundles of nerves of ducts of respiratory and intestinal epithelium, and of sheets of hornifying skin. The haphazard disarray of tissues supported the notion that the lesion was not a remnant of a malformed embryo. Step-sections through the lesion revealed no traces of placental villi or decidua in the surrounding endometrium. The following were considered as possible origins of the teratoma: 1. displaced germinal cells, 2. retention of pluripotent müllerian epithelium, 3. overaged or blighted ovum. The latter seems most compatible with the histological findings.