Energy-dependent volume regulation in primary cultured cerebral astrocytes

Cell volume regulation and energy metabolism were studied in primary cultured cerebral astrocytes during exposure to media of altered osmolarity. Cells suspended in medium containing 1/2 the normal concentration of NaCl (hypoosmotic) swell immediately to a volume 40-50% larger than cells suspended in isoosmotic medium. The cell volume in hypoosmotic medium then decreases over 30 min to a volume approximately 25% larger than cells in isoosmotic medium. In hyperosmotic medium (containing twice the normal concentration of NaCl), astrocytes shrink by 29%. Little volume change occurs following this initial shrinkage. Cells resuspended in isoosmotic medium after a 30 min incubation in hypoosmotic medium shrink immediately to a volume 10% less than the volume of cells incubated continuously in isoosmotic medium. Thus, the regulatory volume decrease (RVD) in hypoosmotic medium involves a net reduction of intracellular osmoles. The RVD is partially blocked by inhibitors of mitochondrial electron transport but is unaffected by an inhibitor of glycolysis or by an uncoupler of oxidative phosphorylation. Inhibition of RVD by these metabolic agents is correlated with decreased cellular ATP levels. Ouabain, added immediately after hypoosmotic induced swelling, completely inhibits RVD, but does not alter cell volume if added after RVD has taken place. Ouabain also inhibits cell respiration 27% more in hypoosmotic medium than in isoosmotic medium indicating that the (Na,K)-ATPase-coupled ion pump is more active in the hypoosmotic medium. These data suggest that the cell volume response of astrocytes in hypoosmotic medium involves the net movement of osmoles by a mechanism dependent on cellular energy and tightly coupled to the (Na,K)-ATPase ion pump. This process may be important in the energy-dependent osmoregulation in the brain, a critical role attributed to the astrocyte in vivo.

Single sinusoids compared with a multiple-sinusoids technique for evaluating horizontal semicircular canal function

The vestibulo-ocular reflex (VOR) of 162 normal subjects was evaluated using two rotational testing procedures. Data from 79 subjects were collected using a set of five single-frequency stimuli (0.01 to 0.16 Hz) and 83 subjects were tested using multifrequency stimuli (0.01 to 0.27 Hz). The use of multifrequency stimuli in place of single frequencies reduced testing time from 75 min to 20 min per subject. The diagnostically useful phase response of the VOR, as estimated by the two tests, were not statistically different. Equivalent phase measures may be obtained within a shorter testing period using the multifrequency procedure.

A mastectomy--how so? An etymologic plea

The word mastectomy and its modifiers are used so loosely and have so many meanings in the literature that it is often difficult to determine precisely what procedure the authors are discussing. Simple descriptive terms should be used that would standardize the terminology with respect to operative techniques. The classical term radical mastectomy should be reserved to refer to a complete en bloc resection of the breast with the pectoralis major and minor muscles and the entire axillary contents, with or without a skin graft for wound closure. A total mastectomy should indicate a complete resection of the breast, including the fascia of the pectoralis major muscle. A local excision should be defined as a resection of the primary tumor with margins that are free of disease, with specific margins stated if desired. The axillary lymph node dissection should be defined according to the extent of the axillary contents excised.

Hyperthermia-induced seizures in rat pups with preexisting ischemic brain injury

To investigate the mechanism(s) relating perinatal brain injury to increased seizure sensitivity in the developmental age period, we studied hyperthermia-induced seizures in rat pups with a preexisting unilateral ischemic cerebral injury. At 2 days of age, the pups underwent a carotid artery ligation followed by 20 min of anoxia. By light microscopy, there were no pathologic changes in the postischemic cerebral cortex at 5, 10, or 20 days of age. Seizures were induced by hyperthermia at 5, 10, 15, or 20 days of age. Seizure temperature thresholds increased with maturation in both postischemic and control animals. Temperature thresholds for behavioral seizures were significantly lower at 10, 15, and 20 days in postischemic pups, compared with control animals. By EEG criteria, seizure thresholds also were lower at 10 and 15 days in the postischemic pups compared with control animals. Preictal EEG slowing appeared at the same temperature in experimental and control animals at all ages. We conclude that the rat pup is an appropriate model for the study of enhanced epileptogenesis in the presence of a perinatal ischemic encephalopathy.

Management of bleeding angiodysplasia of the upper small intestine

Five patients thought to have bleeding angiodysplasia in the distal duodenum and proximal jejunum were treated surgically after conservative measures failed to control hemorrhage. Aspiration through a long oral tube preoperatively and intraoperative endoscopy were most helpful in locating the site of bleeding.

Adjuvant CMFP versus CMFP plus tamoxifen versus observation alone in postmenopausal, node-positive breast cancer patients: three-year results of an Eastern Cooperative Oncology Group study

After mastectomy, 265 postmenopausal patients with node-positive breast cancer were stratified according to pathologic nodal status and estrogen-receptor (ER) status and randomized to receive either 12 cycles of cyclophosphamide, methotrexate, 5-fluorouracil, and prednisone (CMFP), or CMFP plus tamoxifen (CMFPT), or observation alone. Patients entered the study between March 1978 and July 1981. Cox regression analysis indicated that, compared to observation alone, chemotherapy (CMFP and CMFPT groups combined) led to a significant reduction in relapses by the end of the first year of study in every examined prognostic subgroup. However, after the first year the relapse-free survival curves of all treatment groups tended to merge, so that by three years 52% of the observation group and 51% of the chemotherapy groups remained disease free. Chemotherapy continued to show a significantly superior relapse-free survival rate for three years only in the subgroup of patients with ER-negative tumors (the subgroup with the largest relapse-free survival advantage at one year). The addition of tamoxifen produced no benefit or harm in any prognostic subcategory examined. ER status was prognostically important for predicting early relapse only in those patients not receiving chemotherapy, due to the greater effectiveness of this chemotherapy to prevent early relapse in the ER-negative subgroup. Treatment has had no early effect on survival. As breast cancer continues to recur even after ten or more years, later relapse patterns may alter these results.

Changing concepts of acoustic neuroma diagnosis

Three hundred five acoustic neuromas were reviewed to determine the sensitivity of combining the auditory brainstem response (ABR) and the intravenous contrast-enhanced computed tomogram (CT) as screening tests for acoustic neuroma diagnosis. The ABR detected 98% of the tumors. The enhanced CT demonstrated 97% of tumors larger than 1.5 cm, but only 48% of neuromas 1.5 cm or smaller. The combination of both ABR and enhanced CT, used as the initial screening tests, identified 99% of the neuromas. We conclude that ABR, with enhanced CT as needed, is an accurate screening protocol. This method can be used as an alternative to the traditional ABR, electronystagmography, and internal auditory canal tomograms.

Cases from the aerospace medicine residents' teaching file. Case #2. An aviator with acoustic neuroma

From the Aerospace medicine residents' teaching file: on aviator with acoustic neuroma. The clinical presentation, evaluation and disposition of a patient with an acoustic neuroma are discussed.

Effects of anticonvulsants on hyperthermia-induced seizures in the rat pup

We studied the effects of phenobarbital (PB), valproic acid (VPA), and phenytoin (PHT) on the electroencephalograms and behaviorally defined seizure threshold temperatures in rat pups exposed to ambient hyperthermia on the fifth day of life. Animals injected with 10, 20, or 40 micrograms PB/g body weight (GBW) or 80, 150, or 300 micrograms VPA/GBW daily from the second day of life showed seizure temperature thresholds that were about 1.0 degree C higher than those of controls. Pups injected with PHT had thresholds that were equal to or lower than those in controls despite blood levels greater than 20 micrograms/ml. Preictal rhythmic sharp wave activity appeared in VPA-injected animals at temperatures below the threshold temperature. All experimental animals showed electrographic epileptiform activity at the threshold temperatures. We conclude that this animal model shows similar anticonvulsant efficacies to those found in human febrile seizures. This model may be useful in determining the efficacy of potentially useful anticonvulsant drugs and their mechanisms of action.

Responses to rotational stimulation of the horizontal canals from patients with acoustic neuromas

Studies of eye movement responses to harmonic acceleration in patients with acoustic neuromas and Meniere's disease have demonstrated left-right asymmetries and phase decrements. This study examined the responses from 41 patients with acoustic neuromas. The phase measures and the frequency components of the response (spectral purity) were examined in detail. Results of the study suggests that phase decrements, although they are nonspecific responses of the vestibular system to injury, have different characteristics depending on the location of the lesion. In addition, when the injury is in the eighth nerve root entry zone, the linearity of the system reflects a severe decrement.

Use of high resolution thin section CT scanning of the petrous bone in temporal bone anomalies

High resolution thin section axial CT scans (REVIEW reconstruction ARRANGE reformation--General Electric copyright were utilized to evaluate the petrous bone of 17 patients, ages 3 to 60, with congenital hearing loss. Two scanning protocols were evaluated: 1.5 mm thick sections at 1.5 mm intervals, and 1.5 mm thick sections at 1.0 mm intervals. These protocols were qualitatively compared with regard to 1. visualization of small anatomical structures, and 2. computer reformatted images in coronal and sagittal planes. Our experience suggests this imaging capability is highly useful in th evaluation of congenital ear abnormalities. Seventeen patients were examined with high resolution CT scans. The inner ear abnormalities included varying degrees of Mondini's dysplasia. The large vestibule, the large fenestra into the internal auditory canal, as well as the poor cochlear formation, were seen in these malformations. These studies have allowed a greater degree of accuracy in counseling parents of patients with inner ear malformations. Middle and external ear deformities were also encountered. The imaging technique is capable of demonstrating ossicular deformities, as well as the nature of canal atresias. It is particularly useful in the planning of surgery on some of these patients in that location of the plane of the facial nerve canal can be determined prior to surgery. This provides the ability to determine whether surgery is possible, and if so, the probability of opening the middle ear adequately to obtain appropriate reconstruction. Illustrative cases demonstrate the ease of visualizing the small structures of the inner and middle ear and the ability to review these structures in any plane utilizing the ARRANGE program.

Factors influencing the growth and respiration of rat cerebral astrocytes in primary culture

Cell densities and respiratory rates of astrocytes from neonatal rat brain grown in primary culture were determined after 20-30 days in vitro. Cells grown in flasks reached lower densities (microgram DNA/cm2) and higher protein:DNA ratios than cells grown in petri dishes. Respiratory rates were lower for cells grown in flasks compared to cells grown in dishes. The pH of the medium in flasks fell below 6.9 between feedings while the pH of the medium in dishes remained at about 7.2. Cells grown in dishes with the medium pH adjusted to 6.8 also showed lower final cell densities, higher protein:DNA ratios, and lower respiratory rates, compared to cells grown under similar conditions at pH 7.5. Intermediate values of each parameter were found in cells grown at pH 7.5 for one week and then at 6.8 for 20 days. We conclude that the effects of ambient pH account for the differences in growth characteristics and respiratory rates of astrocytes grown in dishes versus those grown in flasks.

Laser microirradiation of cerebellar neurons in culture. Electrophysiological and morphological effects

Electrophysiological and ultrastructural effects of focused laser radiation on neurons from neonatal rat cerebellum in tissue culture are reported. Action potentials were elicited by an extracellular current pulse train. The stimulator voltage required for half-maximum response frequency was measured as a function of the energy delivered by a single laser pulse. Above a "threshold" laser energy, the cell response to stimulation became negligible for all stimulator voltages. Electron micrographs of cells revealed that the mitochondria are preferentially damaged at an energy comparable to the electrophysiological threshold. The damaged mitochondria showed swollen matrix space and disrupted cristae membranes. Higher laser energies resulted in damage to other cytoplasmic structures. The results are consistent with a model that assumes that light interaction with the nerve cells proceeds by local heating of the mitochondria and nearby structures and leads to an increased conductance of the membrane to some ionic species.

Symposium on low frequency harmonic acceleration, the rotatory chair. Responses to low-frequency harmonic acceleration in patients with acoustic neuromas

There has been increased interest in harmonic acceleration (HA) for the evaluation of vestibular pathology in recent years. The purpose of this study was to determine the value of harmonic acceleration testing in 24 patients with surgically proven acoustic neuromas. All patients were tested preoperatively and postoperatively, and none were lost to follow-up. Thirteen were tested one year or more after surgery. For rotational evaluation, each patient was seated in an enclosed chair driven by a D.C. torque motor turntable system and rotated utilizing five low frequency sinusoids (.01 - .16 Hz). Slow eye movements in response to acceleration were analyzed by analog and digital computer techniques. Output measures were the phase relationships between the input stimulus velocity and the slow phase eye movement velocity and labyrinthine preponderance (LP) or asymmetry. Preoperative results showed that caloric examination identified 79% of patients with tumors and HA 67% (2 standard deviation criteria). When both tests were evaluated together they identified 91% of all patients with tumors. Of the 4 small tumors (less than 2 cm), HA identified 4 and caloric examination 2. All patients were tested approximately 7 days postoperatively and had statistically significant shifts in their phase and LP measures. The shifts in phase were stable up to 3 years after surgery; however, the LP returned toward normal values. These findings indicate that the vestibular system can compensate but not repair itself after the loss of one labyrinth. In those patients who continued to be symptomatic 1 year or more after surgery, the LP did not return to normal values. Harmonic acceleration testing complemented caloric testing in the identification of patients with tumors and objectively demonstrated patients with continued symptomatology after surgery.

Comparison of subjective symptomatology and responses to harmonic acceleration in patients with Menière's disease

Vestibular function testing employing caloric stimulation has been of limited value in the evaluation of patients with Menière's disease, with its cardinal shortcoming being poor repeatability. This modality has not been useful in determining appropriate treatment for these individuals. We have used low frequency harmonic acceleration to study patients with vestibular pathology and have noted a high level of repeatability of responses to this type of stimulation. This study was designed to determine if the clinical status of patients with Menière's disease could be correlated with their responses to harmonic acceleration. Thirty-six patients with typical symptoms of Menière's disease were evaluated and divided into four groups based on severity of symptoms. Analysis of variance of the phase shifts in asymmetry (or preponderance) showed a significant difference between the groups. Responses to this type of stimulation correlated with the clinical status of the patients to a significant degree. These data indicate that harmonic acceleration can be of value to the otologist in the evaluation of patients with Menière's disease.

Laser action spectrum of reduced excitability in nerve cells

The change in excitability of unstained nerve cells from neonatal rat cerebellum was measured as a function of the energy flux and wavelength of incident laser light. The energy flux was in the range of 0 to 100 microJ/sq. microns. 6 wavelengths between 490 and 685 nm were used. Laser pulses above a threshold energy flux significantly reduced the cells' excitability as measured by extracellular stimulation. The sensitivity of the cells, defined as the inverse of the threshold energy density, increased by an order of magnitude toward the shorter wavelengths. These results are consistent with primary absorption of the light by mitochondrial enzymes, resulting in local heating followed by mitochondrial calcium release into the cytoplasm.

Persistent hoarseness: an aggressive approach for early detection of laryngeal cancer

Persistent hoarseness in a patient should always alert the physician to the possibility of laryngeal carcinoma. Prompt visualization of the larynx is essential, particularly in high-risk patients over 40 years of age without a history of upper respiratory infection. Mirror examination (indirect laryngoscopy) is the usual initial diagnostic procedure, although Hopkins' rod telescope and the fiberoptic laryngoscope may provide more adequate visualization. Direct laryngoscopy and biopsy allow definitive diagnosis.

Respiration in rat cerebral astrocytes from primary culture

Respiration was measured polarographically in astrocytes from dissociated neonatal rat cerebra grown in primary culture. Cells grown in a modified Eagle's minimal essential medium containing 20% fetal calf serum for 14 to 21 days respired at a rate of 34.23 n at. equiv 0 mg protein-1 min-1. Cells which were grown in this medium for 14 days and the grown in serum-free medium containing 0.25 mM dibutyrylcyclic-AMP (dbcAMP) for three to six days, had respiratory rates 20% higher than in cells from untreated control cultures (P = 0.005). Maximal inhibition by oligomycin required 200 pmole per mg protein for dbcAMP-treated cells and 80 pmole per mg protein for untreated cells. Oligomycin inhibited the respiration of both dbcAMP-treated and untreated cells by about 70%. At a concentration of 175 nmole per mg protein, 2,4-dinitrophenol (DNP) produced a maximal stimulation of respiration, which was 191% of the resting rate in dbcAMP-treated cells and 218% of the resting rate in untreated cells. The maximal DNP-stimulated respiratory rates were the same in dbcAMP-treated and untreated cells.

The use of glucagon in operative cholangiography

We have found intravenously administered glucagon to be useful in relaxing the sphincter of Oddi during operative cholangiography. It is readily available, has few potential side-effects, is easily administered intraoperatively and has been promptly and reliably effective.