Sex- and Age-Specific Differences in Mice Fed a Ketogenic Diet.

The ketogenic diet (KD) is a high-fat, low-carbohydrate diet that results in the elevation of serum ketone bodies, known as ketosis. This metabolic consequence has been suggested as a method for treating neurological conditions, improving exercise performance, and facilitating weight loss for overweight individuals. However, since most research primarily uses male populations, little is known about the potential sex differences during the consumption of the KD. In addition, the effects of the KD on aging are relatively unexplored. Therefore, the purpose of this study was to explore sex- and age-specific differences in mice fed the KD. Male and female C57BL/6N mice at either 12 wks or 24 wks of age were randomly assigned to a KD (90% fat, 1% carbohydrate) or chow (13% fat, 60% carbohydrate) group for 6 wks. KD induced weight gain, increased adiposity, induced hyperlipidemia, caused lipid accumulation in the heart and liver, and led to glycogen depletion in the heart, liver, and muscle with varying degrees of changes depending on age and sex. While younger and older male mice on the KD were prone to glucose intolerance, the KD acutely improved rotarod performance in younger females. Overall, this study highlights potential sex and aging differences in the adaptation to the KD.

The Effects of Exercise Training on Glucose Homeostasis and Muscle Metabolism in Type 1 Diabetic Female Mice.

Although exercise training is an important recommendation for the management of type 1 diabetes (T1D), most of the available research studies predominantly focus on male subjects. Given the importance of sex as a biological variable, additional studies are required to improve the knowledge gap regarding sex differences in T1D research. Therefore, the purpose of this study was to examine the role of exercise training in mediating changes in glucose homeostasis and skeletal muscle metabolism in T1D female mice. Female mice were injected with streptozotocin (STZ) to induce T1D. Two weeks after STZ injection, control (CON) and STZ mice were exercise trained on a treadmill for 4 weeks. Aerobic exercise training failed to improve glucose tolerance, prevent the decrease in body weight and adipose tissue mass, or attenuate muscle atrophy in T1D female mice. However, insulin sensitivity was improved in T1D female mice after exercise training. Aerobic exercise training maintained skeletal muscle triglyceride content but did not prevent depletion of skeletal muscle or liver glycogen in T1D mice. Gene expression analysis suggested that T1D resulted in decreased glucose transport, decreased ketone body oxidation, and increased fatty acid metabolism in the skeletal muscle, which was not altered by exercise training. These data demonstrate that 4 weeks of aerobic exercise training of a moderate intensity is insufficient to counteract the negative effects of T1D in female mice, but does lead to an improvement in insulin sensitivity.

Experience with the SOUNDTEC implantable hearing aid.

OBJECTIVE: To assess the efficacy, morbidity, and patient satisfaction of the SOUNDTEC semi-implantable hearing aid. STUDY DESIGN: Retrospective case review. SETTING: Two tertiary referral centers (the Silverstein Institute and the Atkins Institute). PATIENTS: Sixty-four (four bilateral placements) patients with bilateral moderately severe sensorineural hearing loss: 47 patients had previously worn hearing aids. INTERVENTIONS: After separating the incudostapedial joint, a magnet encased in a titanium canister with a ring was introduced onto the stapes neck. Gelfoam or adipose tissue was used to stabilize the magnet. After 3 months, the external processor was fitted. MAIN OUTCOME MEASURES: At 1 month, audiometric testing was performed and functional gain was assessed. Patient acceptance and implant performance were measured by a visual analogue questionnaire. RESULTS: The device produced an average functional gain of 26 dB. Fifty-five percent of patients complained of magnet movement; this was eliminated in 80% of Silverstein Institute patients when the external processor was worn and fat was used to stabilize the magnet. CONCLUSION: The SOUNDTEC direct device is well tolerated in the majority of patients, with a significant increase in functional gain. Magnet instability and noise were the most frequent complaints and improved with processor placement and anchoring the magnet with fat. This electromagnetic semi-implantable hearing aid confers greater functional gain over conventional hearing aids and reduces occlusion effect and feedback.

Hearing outcome of laser stapedotomy minus prosthesis (STAMP) versus conventional laser stapedotomy.

OBJECTIVE: The objective of this study was to compare short-and long-term hearing outcomes for patients undergoing primary laser stapedotomy minus prosthesis (STAMP) versus conventional laser stapedotomy. STUDY DESIGN: We conducted a retrospective case review of 167 consecutive patients from 1993 to 2002. SETTING: Otology/neurotology tertiary referral center. PATIENTS: We studied those with clinical otosclerosis without previous otologic surgery. INTERVENTIONS: Patients with otosclerosis confined to the fissula ante fenestram underwent STAMP. Patients with more extensive otosclerosis or anatomic contraindications to STAMP underwent standard laser stapedotomy. MAIN OUTCOME MEASURES: Pure-tone audiometry was performed before surgery, postoperatively, and on routine follow-up examination. RESULTS: Of the 183 ears in 167 patients, 128 (67.1%) underwent laser stapedotomy and 55 (32.98%) underwent STAMP. The STAMP mean air-bone gap (ABG) closed from a preoperative value of 22 dB (standard deviation [SD], 10 dB) to 6 dB (SD, 7 dB) on average follow up of 778 days. In 128 laser stapedotomy patients with an average follow up of 747 days, the preoperative mean ABG closed from 27 dB (SD, 10 dB) to 8 dB (SD, 7 dB). There was a trend toward improvement in high-frequency air conduction thresholds after STAMP versus worsening of high-frequency thresholds in the conventional stapedotomy group. There was a statistically significant improvement in most recent postoperative high-frequency (6000-8000 Hz) air conduction thresholds in the STAMP patients compared with patients who underwent conventional laser stapedotomy. CONCLUSION: Laser STAMP, when used for isolated anterior footplate otosclerosis, provides excellent high-frequency hearing, yields lasting results similar to conventional laser stapedotomy, and has a low incidence of refixation necessitating revision surgery.

Direct application of dexamethasone for the treatment of chronic eustachian tube dysfunction.

We undertook a prospective study to determine the safety and effectiveness of the direct administration of a steroid to the eustachian tube via the Silverstein MicroWick in 11 patients with chronic eustachian tube dysfunction, including two who had Samter's triad. All patients had previously been treated with medical therapy and surgical middle ear ventilation without resolution. The MicroWick was placed directly in the eustachian tube orifice through a pressure-equalization tube. Patients received 3 drops of dexamethasone 4 mg/ml three times a day. The drops were discontinued after 4 weeks, and the MicroWick and ventilation tube were removed after 3 months. At study's end, eight patients (72.7%) reported subjective improvement in terms of a reduction in aural pressure and fullness. Audiometric testing demonstrated a 55% reduction in the mean air-bone gap and a 3% increase in the mean speech discrimination score. Bone pure-tone averages remained stable. Tympanometry showed that five patients (45.5%) converted from type B or C tympanograms to type A. Four patients (36.4%) had persistent perforations. Both patients with Samter's triad improved with therapy. These preliminary results suggest that direct dexamethasone administration to the eustachian tube is safe and effective for the treatment of chronic eustachian tube dysfunction. Long-term studies to confirm these findings are under way.

Changing trends in the surgical treatment of Ménière's disease: results of a 10-year survey.

In order to discern trends in surgical procedures used to treat Ménière's disease in the United States during the 1990s, we mailed a questionnaire to 700 members of the American Otological Society and the American Neurotology Society. These physicians were asked about the frequency, results, and complications of surgical procedures for Ménière's disease that they had performed between Jan. 1, 1990, and Dec. 31, 1999. Questionnaires were returned by 137 surgeons (19.6%). Their responses indicated that the number of vestibular neurectomies, labyrinthectomies, and endolymphatic sac surgeries all decreased during 1999. Meanwhile, the use of office-administered intratympanic gentamicin therapy increased rapidly throughout the entire 10-year period, and by 1999 it had become the most frequently used invasive treatment for Ménière's disease. Surgeons now seem to reserve inpatient procedures for cases where intratympanic gentamicin fails to control vertigo.