Amino acid receptors of midget and parasol ganglion cells in primate retina.

Primate retinas contain two major ganglion cell types. Midget (or P type) cells have relatively sustained responses to light; the amplitude and polarity of these responses vary with stimulus wavelength. Parasol (or M type) cells are more sensitive to stimulus contrast and respond more transiently but are not selective for color. Both types can be further subdivided into a and b subtypes, according to the level of their dendritic stratification in the inner plexiform layer. To determine whether differences in receptors for amino acid transmitters are the basis for any differences in ganglion cell light responses, we made whole-cell, patch-clamp recordings from identified ganglion cells in slice preparations of macaque and baboon retinas. We found that midget and parasol cells of both a and b types had similar responses to excitatory amino acids, including kainate, alpha-amino-3-hydroxy-5-methylisoxalzole-4-propionic acid, and N-methyl-D-aspartate, with reversal potentials near the equilibrium potential for cations. Kainate responses were blocked by 6,7-dinitroquinoxaline, and N-methyl-D-aspartate responses were blocked by D-(-)-2-amino-7-phosphonoheptanoic acid. The four types of ganglion cells also had similar responses to bath-applied inhibitory amino acids. All cells had both gamma-aminobutyric acid and glycine receptors with reversal potentials near the equilibrium potential for Cl-, and the relative amplitudes of the responses to excitatory and inhibitory amino acids were similar among the various cell types. These results suggest that the differences in response properties of the different classes of ganglion cells in primate retina may be determined, to a significant degree, by the properties of the amacrine and bipolar cells that provide their input rather than by the nature of their postsynaptic receptors.     

Unified model of tectonics and heat transport in a frigid Enceladus

Recent data from the Cassini spacecraft have revealed that Enceladus, the 500-km-diameter moon of Saturn, has a southern hemisphere with a distinct arrangement of tectonic features, intense heat flux, and geyser-like plumes. How did the tectonic features form? How is the heat transported from depth? To address these questions, we formulate a simple model that couples the mechanics and thermodynamics of Enceladus and gives a unified explanation of the salient tectonic features, the plumes, and the transport of heat from a source at a depth of tens of kilometers to the surface. Our findings imply that tiny, icy moons can develop complex surficial geomorphologies, high heat fluxes, and geyser-like activity even if they do not have hot, liquid, and/or convecting interiors.     

“The Stork Lift”: A Circumoccipital Extended Neck-Lift

Background  The goal of the lower face- and neck-lift is restoration of a sharp cervicomental angle. However, standard cervical rhytidectomy for the patient with extensive excess skin of the neck often leaves the patient with objectionable vertical or diagonal skin folds of the lateral neck, a large hair-step deformity, or both. To remove extensive excess skin of the neck and to avoid vertical/diagonal folds and a stepped hairline, the authors “walk” the excess skin posteriorly along the hairline, often from ear to ear along the inferior posterior hairline. Methods  Patients with extensive excess skin of the neck underwent neck-lift procedures using the circumocciput incision technique during a 1-year period. With the patient in a sitting position, a postauricular face-lift incision is extended along the inferior hairline from ear to ear. The flap is “walked” posteriorly to and along the occiput on either side of the midline. It is closed using a divide and close technique. Flaps are created, and the wound is closed in a multilayered fashion with a posterior midline A-to-T flap. Results  During a 1-year period, 25 patients (22 women and 3 men) underwent a cheek/neck-lift, and 2 patients (1 man and 1 woman) underwent isolated neck-lift procedures using the circumocciput incision technique. The average patient age was 64.8 years (range, 49–79 years). There were no instances of obvious lateral neck folds. Complications included hematoma (1 patient), Candida wound infection (1 patient), and a widened scar revised secondarily (1 patient). All the patients were satisfied with their cosmetic result 6 months after the operation. None of the patients stated that their final scar was noticeable or objectionable. Conclusions  The patients in this study who presented with excessive redundant skin of the neck were treated with the “stork lift,” which provided excellent lifting of the anterior, lateral, and posterior neck as well as excellent cervicomental angles without postoperative sequelae of lateral neck folds or stepped hairlines.     

Invasive well-differentiated thyroid carcinoma: effect of treatment modalities on outcome.

OBJECTIVE: Well-differentiated thyroid carcinoma is considered an indolent malignant disease. Although rare, extrathyroidal invasion is associated with a worse prognosis and increased risk of morbidity. Management remains controversial, with some authors advocating conservative treatment with preservation of midline structures and others, aggressive extensive en bloc resection. The aim of this study was to report our 40-year experience with invasive thyroid carcinoma, with emphasis on the clinical characteristics and the effect of different treatment modalities on survival. STUDY DESIGN AND SETTING: A retrospective study including a file review of 1,200 patients with a diagnosis of well-differentiated thyroid carcinoma of whom 49 (5%) showed involvement of an adjacent structure (larynx, trachea and esophagus) (study group). Type of surgery, radiation treatment, radioiodine treatment, and patient demographics were evaluated. RESULTS: Compared to the rest of the patients, the study group was characterized by a higher rate of male patients (39% vs 25%), and older average age (58 vs 45 years). Average size of the primary tumor was 3.7 cm. Sixteen patients underwent radical surgery and 33 conservative surgery followed by radioiodine treatment. Five-year survival and recurrence rates for the whole group were 78% and 52%, respectively. The only statistically significant factor for survival was large tumor size. Distant metastases developed in 46% of patients, all in the lungs. Ten of 14 deaths were due to distant metastases. External radiation, used in 52% of the patients, was associated with worse prognosis. CONCLUSION: Conservative procedures followed by radioiodine treatment are associated with similar survival rates as aggressive techniques, with less perioperative mortality and lower overall morbidity. SIGNIFICANCE: This study provides further evidence that in cases of invasive thyroid tumors the extent of the primary surgery seems to have no influence on survival. EBM rating: C-4.     

Use of prone-pressure device for visualizing hiatus hernia

Summary and conclusion 1. A case of hiatus hernia has been reported which was visualized most effectively after use of a prone-pressure abdominal pad (Wolf's method).2. This procedure increases intra-abdominal pressure, without increasing intrathoracic pressure and does not require the active participation of the patient.