The role of calcium ion in methoxamine-induced amylase release from parotid glands of euthyroid and hypothyroid rats

The change in responsiveness to alpha-adrenergic stimulation and to calcium ions in amylase release from parotid glands of hypothyroid rats was compared with that in euthyroid rats. Calcium depletion and addition of verapamil or W-7 in the medium caused a decrease in methoxamine-induced amylase release in both eu- and hypothyroid rats. Moreover, addition of calcium ions to Ca2+-free medium markedly increased the methoxamine-induced amylase release in proportion to its concentration in hypothyroid rats. These results suggest that calcium ions play an important role in methoxamine-induced amylase release from parotid glands of hypothyroid rats as well as those of the euthyroid ones.

gamma-Aminobutyric acid acts at axon terminals of turtle photoreceptors: difference in sensitivity among cell types

It has been proposed that horizontal cells of the vertebrate retina have a negative feedback synapse with cone photoreceptors. gamma-Aminobutyric acid (GABA) has been suggested to be a neurotransmitter of monophasic horizontal cells (a subtype of horizontal cells), which have direct connections with red-sensitive and green-sensitive cones. We have examined the feedback hypothesis by measuring the GABA sensitivity of photoreceptors. To eliminate interaction with other cells, we dissociated photoreceptors from the turtle retina enzymatically. The subtype of photoreceptors was identified unequivocally on the bases of the shape of the cell and the color of the oil droplets, which are known to correlate with the spectral sensitivity. Cells were voltage-clamped using "Giga-ohm sealed" suction pipettes in the whole-cell recording configuration, and membrane currents were measured in response to GABA applied ionophoretically at various positions on the cell. It was found that red-sensitive and green-sensitive cones were highly sensitive to GABA and that the sensitivity was localized at the axon terminals. GABA-sensitivity in blue-sensitive cones and in rods was very low. GABA-induced current reversed its polarity near the equilibrium potential of chloride, suggesting that GABA increased chloride conductance. Thus, our findings are consistent with the negative feedback hypothesis.

Duane's syndrome associated with crocodile tear and ear malformation. A case of stapes anomaly and its reconstruction

Duane's syndrome is a congenital eye movement disorder characterized by marked limitation or absence of abduction, variable limitation of adduction, and narrowing of the palpebral fissure with retraction of the globe on attempted adduction. We treated a patient with bilateral Duane's syndrome associated with crocodile tear and external, middle, and inner ear anomalies. Exploratory tympanotomy showed an absence of the oval window and a rudimentary superior structure of the stapes that was connected to the abbreviated incudal lenticular process with connective tissue. A small hole was drilled into the vestibulum and the ossicular chain was reconstructed by inserting a Teflon wire piston to minimize the air-bone gap. Pertinent literature is reviewed, and the pathogenesis of Duane's syndrome and the aspect of concomitant anomalies are discussed.

Studies of the substructures of the lysozyme-rich secretory granule of the serous cell in the human nasal gland

Using a protein A-gold immunohistochemical technique, the lysozyme rich core and the lysozyme free peripheral rim were differentiated in the secretory granule of the serous cell in the human nasal mucosa, under the electronmicroscope. The shperical lysozyme rich core, which had been excreted into the gland lumen, was also wrapped with the peripheral rim. This finding suggests that the peripheral rim defends the integrity of the core and inhibits the release of lysozyme from the core.

Responses of solitary retinal horizontal cells from Carassius auratus to L-glutamate and related amino acids

Effects of L-glutamate and its analogues on membrane potentials of solitary horizontal cells were studied by intracellular recording. L-glutamate depolarized these cells at micromolar concentrations (greater than or equal to 10 microM), while D-glutamate and L-alpha-amino adipic acid produced slight depolarizations only at millimolar concentrations. Neither L- nor D-aspartate, even at millimolar doses, produced any change in solitary horizontal-cell resting potential. Solitary horizontal-cell responses to L-glutamate did not desensitize detectably. Responses to pairs of brief, ionophoretic pulses of L-glutamate were nearly equal in amplitude at inter-pulse intervals as short as 50 ms. Responses to maintained applications of low doses of L-glutamate did not decline for as long as 2 min. Depolarizing responses were produced by ionophoretic applications of L-glutamate near cell somata as well as dendrites. The mean sensitivity was 1.4 +/- 1.5 mV/nC with a maximum of 5.1 mV/nC. Depolarizing responses to L-glutamate reversed in polarity at membrane potentials between 0 and -20 mV, were accompanied by a decrease in membrane slope resistance, and were suppressed by replacement of extracellular sodium ions with choline. These results demonstrate that chemosensitivity of retinal horizontal cells to acidic amino acids persists after dissociation protocols, and in several respects resembles that found in horizontal cells in situ. These findings are consistent with the notion that retinal horizontal cells receive a synaptic input involving L-glutamate or a similar substance.

[Two cases of renal arteriovenous fistula treated by transcatheter embolization with absolute ethanol]

Two cases of renal arteriovenous fistula were treated by transcatheter embolization using absolute ethanol. These were the first cases using absolute ethanol in Japan. The first case was of a 23-year-old male and the other case was of an 18-year-old female. Both patients were admitted to our hospital because of gross hematuria. A selective right renal arteriogram showed an arteriovenous fistula. Hemostasis was obtained by transcatheter embolization using absolute ethanol. The safety and efficacy of injection of ethanol compared with other solid materials and occlusive balloon catheter are reported and its indication for renal arteriovenous fistula is described.

Control of the generator current in solitary rods of the Ambystoma tigrinum retina

THe current suppressed by light, the generator current, was studied in solitary salamander (Ambystoma tigrinum) rod photoreceptors with the single-micropipette voltage-clamp technique. The effects of Ca, cyclic GMP, and voltage were measured while voltage- and Ca-activated currents of the inner segment were blocked with Co, Cs, and TEA (tetraethylammonium). The generator current was increased more than 5-fold by lowering the external Ca concentration from 1.5 mM to 10 microM. The generator current could be decreased approximately 1/2 by injecting Ca into an outer segment. Injection of EGTA quickly increased the generator current approximately 2-fold. After injection ceased, the increase was quickly reversed. The generator current could be increased more than 5-fold by injecting cyclic GMP or 8Br-cyclic GMP. Injection of protons, the pH buffer bicine (N,N-bis[2-hydroxyethyl]glycine), or GMP did not produce a change in the generator current. The current-voltage curve for the generator current was influenced by external Co: in 3 mM-Co the current-voltage curve had a negative resistance between -45 and -90 mV; in 0.1 mM-Co the current-voltage curve paralleled the voltage axis between -45 and -90 mV. The difference is attributed to a voltage-dependent block by Co. Susceptibility to the blocking action of Co was reduced by lowering internal or external Ca concentration, or by injecting cyclic GMP. When rods were bathed in a medium containing 7-100 microM-Ca, a step depolarization produced a time-dependent decline in current. Because the reversal potential remained constant, the decline is attributed to an inactivation. The extent of inactivation was reduced by increasing the concentration of external Ca or injecting cyclic GMP.

The site of involvement of hypertension within the cochlea. A comparative study of normotensive and spontaneously hypertensive rats

The function and morphology of the cochlea of the spontaneously hypertensive rat (SHR) were examined and compared with the age-paired normotensive Wistar Kyoto rat (WKY). Electro- cochleographic study revealed that the function of the cochlea in the SHR declined with increasing age to a greater extent than that of WKY. Electronmicroscopic study revealed that the primary site of the cochlear deterioration of the SHR was the vascular stria, followed by the organ of Corti. Some hypotheses to explain this phenomenon are proposed for further study.

Freeze-replica observations of guinea pig middle ear muscles

The histological characteristics of the middle ear muscles, Musculus tensor tympani and M. Stapedius, of the guinea pig were studied using freeze-fracturing technique. No gap junction was observed but the tight junction was found in the tensor tympani muscle, possibly between muscle cells. No distinct difference was found between the size distributions of the apertures and caveolae on the fracture face of the sarcolemma of the two kinds of muscles.

Renal devitalization with ethanol injection in management of patients with advanced hypernephroma

Transcatheter injection of ethanol into the renal artery was utilized in 11 patients with hypernephromas, clincally staged C or D, in an attempt to produce renal devitalization. Complete disappearance of the tumor neovascularity was achieved in 9 of 11 patients. Renal divitalization with ethanol injection is safer and more effective than the embolizing technique utilized hitherto and should be included in the primary treatment of hypernephroma in selected cases or in conjunction with other procedures to induce chemical nephrectomy.

Localization of triphosphoinositide in the cochlea. An electronmicroscopic immunocytochemical study

Triphosphoinositide (TPI) has been demonstrated to be a receptor for aminoglycosides in the cochlea and may regulate ionic permeability by its binding with Ca++. This phospholipid was localized by a protein A-gold technique in the cochlea at the electronmicroscopic level. TPI was prepared by a neomycin column and antibodies to it were raised in rabbits. The antibody used in this study reacted virtually only to TPI among the tested lipids. TPI was localized mainly at stereocilia, cuticular plates, head plates of Deiters' cells, plasma membrane, and mitochondria of various cells in the organ of Corti. In the vascular stria, TPI was found mainly at the plasma membrane of basal infoldings of the marginal cells. Possible physiological and pathophysiological roles of TPI in the cochlea are briefly discussed.

Ionic currents of solitary horizontal cells isolated from goldfish retina

Solitary horizontal cells, dissociated from papain-treated goldfish retinas, produce action potentials and show a non-linear current-voltage relationship. Underlying ion-conductance mechanisms were analysed by a single-micro-electrode voltage-clamp technique. Pharmacological and ion-substitution experiments revealed that ionic currents could be separated into at least four voltage-dependent currents: a Ca current and three types of K currents. The Ca current was activated by membrane depolarization beyond -45 mV, reached a maximal value near 0 mV, and became smaller at more positive potentials. By extrapolation, the reversal potential was estimated to be approximately +50 mV. The Ca current was inactivated by accumulation of intracellular Ca ions but not by membrane depolarization. Co ions (4mM) blocked this current. The first type of K current showed anomalous (inward-going) rectification near the resting potential (congruent to -60 mV). Hyperpolarization from the resting level produced a large, almost steady inward current, while depolarization evoked only a small, steady outward current. The current-voltage relationship revealed a shallow negative resistance region at membrane potentials beyond -50 mV. The current was blocked by Cs (10 mM) or Ba (1 mM) ions. The second type of K current (the transient outward current) was activated by membrane depolarization beyond -25 mV. The peak amplitude increased almost exponentially as the membrane was depolarized. During steady depolarization this current decayed exponentially (time constant congruent to 500 ms at +20 mV). The current was inactivated by conditioning depolarization (greater than 10 s) beyond -30 mV and blocked by 4-aminopyridine (10 mM). The third type of K current was the maintained outward current which was activated by membrane depolarization beyond -20 mV, increased to a steady level in a few hundred milliseconds, and showed little inactivation. The amplitude increased as the membrane was depolarized. The current was blocked by tetraethylammonium ions (20 mM). A Ca-mediated K current was not detected. Action potentials and the non-linear current-voltage relationship of solitary horizontal cells can be explained qualitatively by the combination of the four ionic currents.

One-stage total cystectomy and ileal loop diversion in patients over eighty years' old with bladder carcinoma. Pre- and postoperative functional reserve of various organs

During the period from 1976 to 1981, 364 patients with bladder carcinoma were seen at the Keio University Hospital. Extensive preoperative investigation of pulmonary, cardiovascular, and renal function was obtained in all patients. Of the 12 patients studied, 9 underwent a one-stage total cystectomy and ileal loop diversion and the remaining 3 a two-stage procedure. Of the 9 patients, decreased FEV 1.0 per cent by spirometry was noted in 5, ECG abnormality such as bundle branch blocks in 8, and diminished creatinine clearance ranging from 28 to 68 ml/min were observed in all 9. Major postoperative complications included pyelonephritis in 2 patients, pneumonia in 1, pelvic abscess in 2, renal insufficiency in 3, and paralytic ileus in 2. There was no immediate postoperative death. In these elderly patients, functional reserve of the lung, heart, and kidney is less than optimal and is further decreased by major surgical procedures. Therefore, total cystectomy in the elderly patients is justifiable only in a selected group of patients, when functional status of the vital organ is thoroughly worked up and prophylactic and therapeutic measures are instituted promptly if indicated.

[Clinical studies of cefotiam in otorhinolaryngologic infections]

Cefotiam (CTM) was intravenously given to 12 patients with infectious diseases in the field of otorhinolaryngology including 10 cases with chronic suppurative otitis media. Daily doses of CTM were 1 to 4 g. Clinical responses were excellent in 3 patients, good in 5, fair in 1 and poor in 3. The rate of overall clinical effectiveness was 67%. Staphylococcus species were most frequently isolated from the patients and all of them were eradicated by the CTM treatment. No side effects and no abnormal laboratory findings relating to the drug administration were observed.

Recovery of renal function after 72 days of anuria caused by ureteral obstruction

We report a case of restored renal function following 72 days of ureteral obstruction causing anuria, while the patient was maintained with regular hemodialysis. Easy accessibility to hemodialysis might jeopardize the kidney, which could have maintained its function if treated otherwise.

Effects of perilymphatically perfused gentamicin on microphonic potential, lipid labeling and morphology of cochlear tissues

The perilymphatic space of the guinea pig was perfused in situ with artificial perilymph containing [32P] orthophosphate and 3H-glycerol while cochlear microphonic potentials (CM) were monitored. The perfusion of 10 mM gentamicin suppressed CM by 62% within 30 min. 32P-incorporation into phosphatidylinositol bisphosphate in the organ of Corti was decreased but distribution of 3H-glycerol in neutral lipids and phospholipids was not affected by gentamicin. The morphological evaluation included all structures lining the scala media, the spiral ligament, the basal membrane and the vestibular organs. Hair cells sometimes contained small intracellular 'precipitation' lines but, in general, ultrastructure of all tissues was essentially normal and no overt histopathological changes were evident. The observed biochemical changes should, therefore, represent early and primary actions of the drug. This confirms the hypothesis that an interaction with the acidic phospholipid, phosphatidylinositol bisphosphate, is an important step in the ototoxic mechanism of amino-glycoside antibiotics.

[Immunotherapy of postoperative cancer patients with immune RNA-sensitized lymphocytes and tumor antigen]

Tumor cell suspension was prepared from resected tumor tissue of various cancer patients. 1-RNA was extracted from lymphoid tissues of rabbits immunized with each tumor cells and CFA. When the postoperative condition of patient recovered stable, autologous lymphocytes were prepared with blood cell separator (IBM 2997 type) and incubated with I-RNA, then, return to himself. Total number of sensitized lymphocytes was 4 X 10(9) - 1.2 X 10(10). After this passive immunization was finished, active immunization with autologous 3M KCl tumor extract was added. Three of gastrointestinal cancer, 3 of lung cancer, 2 of miscellaneous malignant tumor were treated with this schedule. T-cell ratio, blastogenesis of T-cell with PHA, skin reaction with PPD and PHA, CEA, IAP and Ig in serum was not definitely changed before and after the immunotherapy. But 3 of them, LAI AND LMI became to positive after the treatment and NK cell activity also increased in 3 cases. In these 3 cases, tumor regression was recognized after the treatment. In a case of synovial sarcoma, skin reaction for autologous tumor antigen became to positive and the metastatic lesion in the lung was gradually regressed and regression is still continuing 6 months after the treatment (reduction ratio 90%).

Solitary horizontal cells in culture--I. Their electrical properties

Membrane properties of solitary horizontal cells were examined under current- and voltage-clamp conditions. The resting membrane potential was mainly determined by K ions. The cells produced all-or-none action potentials and showed non-linear current-voltage relationships with inward- and outward-going rectification. Pharmacological and ion-substitution experiments under voltage-clamp conditions revealed that the ionic current was separated into at least four components; a Ca current and three types of K currents (a K current through an anomalous rectifier, a transient outward current, and a maintained outward current). The action potentials and the non-linear current-voltage relationships of solitary horizontal cells were explained from these ionic currents.

Double color-opponent receptive fields of carp bipolar cells

Bipolar cells with double color-opponent receptive fields were found in the carp retina. They were classified into two types depending on their response polarity. In the receptive field center, type I cells showed hyperpolarization to a long wavelength spot (R-) and depolarization to a short wavelength spot (G+), while in the surround they showed R+, G- responses. Type II cells showed responses of opposite polarities to those of type I cells, namely R + G- in the center, and R - G+ in the surround. From their spectral sensitivity, R components were identified as coming from red-sensitive cones, and G components from green-sensitive cones. These bipolar cells are thought to be the origin of double color-opponent receptive fields of retinal ganglion cells.

Solitary horizontal cells in culture--II. A new tool for examining effects of photoreceptor neurotransmitter candidates

Membrane potentials of solitary horizontal cells dissociated from goldfish retinas were intracellularly measured while applying various acidic amino acids. L-glutamate and kainic acid depolarized solitary horizontal cells at micromolar doses. Neither L- nor D-aspartate produced any change in solitary horizontal cell resting potentials. Low-amplitude responses to L-glutamate showed no sign of desensitization. A steady, plateau-like, dose-dependent component of solitary horizontal cell responses to either L-glutamate or kainic acid, though obscured during its rising phase by action potentials, was always recorded during maintained agonist applications. Responses to either L-glutamate or kainic acid reversed in polarity at membrane potentials between 0 and -20 mV. Responses to L-glutamate collapsed reversibly when extracellular sodium ions were replaced by choline ions. Responses to either L-glutamate or kainic acid were antagonized by relatively high doses of D-aspartate. These results demonstrate that retinal horizontal cell chemosensitivity to acidic amino acids persists after dissociation, and in several respects resembles that found in several other preparations, including retinas in situ.

Amylase release from parotid glands of hypothyroid rats. I. Altered responsiveness to adrenergic agents

Effects of adrenergic agents on alpha- and beta-adrenergic receptors of parotid glands from hypothyroid rats were compared with those of euthyroid rats. The sensitivity for amylase release from parotid slices to adrenergic agents did not change even in hypothyroid status because ED50 values for amylase release in both groups were approx. the same: 7 x 10(-8) M for isoproterenol, 4-6 x 10(-6) M for phenylephrine and 10(-5) M for methoxamine. However, the responsiveness of the tissue to those agents which was determined as the maximal amylase release was significantly higher in hypothyroid status than in the euthyroid status. The maximal increases in amylase release in euthyroid and hypothyroid rats were approx. 7.4% and 10.0% of the total in isoproterenol, 3.9% and 7.4% of the total in phenylephrine and 1.3% and 2.7% of the total in methoxamine, respectively. The effect of dibutyryl cyclic AMP mimicked that of isoproterenol, and the responsiveness of the tissue in this case was much higher in the hypothyroid rats than in the euthyroid rats. Furthermore, 10 mM tolbutamide, which completely inhibited the activity of cyclic AMP-dependent protein kinase, blocked isoproterenol-induced amylase release by 66.5% in euthyroid rats, against only 36.3% in hypothyroid rats. These results strongly suggest that the regulation mediated through beta-adrenergic receptors plays a major role in amylase release from rat parotid glands even under hypothyroid status, and the step following cyclic AMP synthesis might, at least in some way, be involved in this regulation.

[Clinical study of cefsulodin on infectious diseases in otorhinolaryngological field]

The clinical effect of cefsulodin (CFS) on Pseudomonas species infections in otorhinolaryngologic field was studied in 10 patients. The overall clinical effectiveness was 80% (excellent 4, good 4, poor 2). The bacteriological response of CFS against Pseudomonas species was evaluated from 11 strains. Eradication rate of Pseudomonas species was 82%. In 1 case, body temperature was rised after injection. No abnormal laboratory findings, relating to the drug, were observed after treatment.

Amylase release from parotid glands of hypothyroid rats. II. Phosphorylation of microsomal proteins and effects of adenosine 3',5'-monophosphate and tolbutamide

The present study was undertaken to examine the phosphorylation of the parotid microsomal fraction from normal and hypothyroid rats and also to compare the effects of cyclic AMP and tolbutamide on the protein phosphorylation in the two groups. After incubation in the presence of cyclic AMP, an increased rate of phosphorylation of three protein bands was revealed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiography. The apparent molecular weights of these proteins were 33,500, 26,000 and 19,000. The small protein band of 17,000 daltons decreased in 32P incorporation in the presence of cyclic AMP. Tolbutamide specifically inhibited 32P incorporation into the three proteins from normal rats, whereas the rate of phosphorylation of these proteins from hypothyroid rats remained essentially the same as that of the control, even in the presence of tolbutamide. These findings strongly suggest the possibility that stimulation of amylase release by the beta-adrenergic agonist or cyclic AMP was associated with phosphorylation of the three parotid microsomal proteins and that cyclic AMP-dependent, tolbutamide-resistant phosphorylation of these proteins from hypothyroid rats plays an important role in the increased responsiveness to beta-adrenergic stimulation.

Multimodal treatment of advanced adult Wilms tumor

We report 2 cases of advanced adult Wilms tumor that were treated with surgery, radiation and chemotherapy. The first patient had relapse of a Wilms tumor in the liver 2 years after nephrectomy. Combination chemotherapy, consisting of actinomycin D and vincristine, radiation therapy and final resection of the liver metastasis were successful and the patient has been free of disease for 4 years. The second patient had undergone transcatheter embolization of the renal artery elsewhere with the tentative diagnosis of an inoperable renal cell carcinoma metastatic to both lungs. A left renal tumor, weighing 4,500 gm., and a tumor thrombus in the vena cava extending to the right atrium were removed, and histologically diagnosed as a Wilms tumor. Subsequent chemotherapy and radiotherapy resulted in complete disappearance of the lung metastases. We conclude that multimodal treatment, namely a well timed combination of surgery, chemotherapy and radiotherapy, could potentially eradicate the disease even at an advanced stage.

Myelolipoma of the adrenal gland

A case is reported of an adrenal myelolipoma producing a retroperitoneal hematoma. A right suprarenal mass with fatty density was detected by a computerized tomography scan. The mass had irregular vessels on the arteriogram. This is the youngest patient reported among those with surgically removed myelolipoma. There was no endocrine activity.

Membrane properties of solitary horizontal cells isolated from goldfish retina

1. Solitary horizontal cells were obtained by dissociating the adult goldfish retina using the enzyme papain. The cells were identified on morphological grounds and could be kept in culture for over a week. 2. Solitary horizontal cells, penetrated with micro-electrodes, had resting potentials of about -75 mV in normal solution. When external K+ concentration was changed, the membrane potential varied from EK calculated from the Nernst equation. 3. All solitary horizontal cells tested showed an action potential in response to superthreshold depolarizing current pulses. The action potential had an overshoot of about +20 mV and a plateau potential lasting for several seconds. 4. The action potential appeared to be Ca-dependent for the following reasons: (a) TTX or low [Na+] did not affect the action potential, (b) Sr2+, Ba2+ or high [Ca2+] enhanced the action potential, while (c) Co2+ or high [Mg2+] blocked it. No regenerative activity has been observed in horizontal cells in the retina but it is possible that the regenerative mechanism is suppressed normally. 5. A role for K+ was indicated by an increase in the duration and amplitude of the action potential on the application of tetraethylammonium. 6. The steady-state current--voltage (I--V) curve, measured by applying constant current pulses, was S-shaped (current on the abscissa) and composed of inward- and outward-going rectifying regions and a transitional region between them. A similar non-linear I--V relationship has been reported in vivo. 7. The transitional region was characterized by a sudden potential jump and hysteresis, suggesting the presence of a 'negative resistance'. This potential jump appeared not to be produced by the Ca-conductance mechanism mentioned above, since similar jumps were observed in the presence of Co2+.

Effect of hypothyroid status on adenosine 3',5'-mono-phosphate-dependent protein kinase of skeletal, heart and diaphragm muscle of rats

Properties of cyclic AMP-dependent protein kinases from skeletal, heart and diaphragm muscles of hypothyroid rats were compared. Increased enzyme activity was observed in skeletal muscle from hypothyroid rats after DEAE-cellulose chromatography. Changes in isozyme distribution were also shown in the hypothyroid status. The elution profile on DEAE-cellulose suggested a possible translocation of the enzyme from the particulate to the soluble fraction in the heart of hypothyroid rats. The turnover rate of the enzyme protein decreased in the skeletal muscle of hypothyroid rats, but the other two organs showed no change even in the hypothyroid status. The activity of heat-stable protein kinase inhibitor increased in the skeletal and the diaphragm muscles in hypothyroid rats, whereas the activity in the heart decreased in the hypothyroid status. These data suggested the possibility that changes in enzyme properties, modification of isozyme distribution, and changes in modulator activity might account for the modulation of muscle function in hypothyroid rats.

Ototoxicity of intracisternal gentamicin in cats

The intrathecal administration of gentamicin has been used to treat bacterial meningitis. However, the influence of this route of administration on the well-known ototoxic activity of gentamicin is unknown. This route of administration should facilitate access to the inner ear and should increase the ototoxic liability. The possible ototoxic and neurotoxic effects of intrathecally administered gentamicin (0.5, 1, 2, 4, 6, 10 mg/day) in cats were evaluated. Hearing thresholds were obtained by a noninvasive technique prior to and on the 7th and 21st days after the initiation of a seven-day dosage regimen. Histological examination of the organ of Corti was routinely done. Additionally, the vestibular organs of one animal on the 4 mg/day regimen were examined. The concentrations of gentamicin in the cerebrospinal fluid were also determined. The data indicate that the 2 mg/day dose may be very close to the threshold dose for ototoxicity when gentamicin is given by intracisternal administration.

Effect of hypothyroid status on adenosine 3',5'-monophosphate-dependent protein kinase of rat kidney

Changes in the properties of cyclic AMP-dependent protein kinase were studied in the kidney of hypothyroid rats. The activity of the crude extract was greater in hypothyroid rats than in normal ones. The ratio of type I isozyme to type II isozyme in hypothyroid rats was about twice that in the normal rats with enzymes from both the cortex and medulla. A higher affinity for the substrates was shown in the enzymes of the hypothyroid rat kidney. The effects of actinomycin D and of heat-stable protein kinase inhibitor on the enzyme activity were the same in both normal and hypothyroid rats. The changes in enzyme properties and isozyme distribution may well play an important role in the hypothyroid rat kidney.

Are aminosugars ototoxic?

The ototoxicity of the kanamycin fragment 3-amino-3- deoxy-D-glucose (3-aminoglucose, kanosamine), was investigated by perilymphatic perfusion in the guinea pig. Concentrations of 10 or 28 mM of this compound had no effect on cochlear microphonic potentials (CM), contrasting with previous observations (Owada 1962). Kanamycin at 1 mM decreased CM significantly under otherwise identical conditions. The action of kanamycin was at least partially reversible.

Effects of acute hypertension on the extravasation of macromolecule in the temporal bone--the possible involvement of the blood-inner ear barrier

In guinea pigs the radioactivity in the vascular beds was washed out by a cardiac perfusion of saline 15 min after the injection of 50 microCi of radioiodinated human serum albumin (RISA). The brain and temporal bones were dissected and a blood sample was obtained. To examine the degree of extravasation of RISA, the extravascular radioactivity in the tissues was measured and expressed as a ratio to that of the blood. Intravenous injection of amphetamine sulfate increased the extravasation in the brain and the temporal bone of the rat but did not increase it in either tissue of the guinea pig. It was proposed that this was because amphetamine did not cause the blood pressure of the guinea pig to reach the "critical level" which would cause the opening of the blood-tissue barrier. In the rat the degrees of extravasation in both the brain and the temporal bone paralleled the maximal mean arterial pressure caused by amphetamine. It is proposed on the basis of these data that there may exist a blood-inner ear barrier and that this barrier has the same characteristics as the blood-brain barrier.

Occurrence of non-ototoxic antibiotic (cephazolin) in the inner ear

Cephazolin, a non-ototoxic antibiotic, and kanamycin, an ototoxic antibiotic, were administered to the guinea pig systemically and their tissue concentration was measured. Not only kanamycin but also cephazolin did occur in the inner ear as well as in the kidney and other tissues. Therefore, it is most likely that the accumulation of an antibiotic inside the inner ear forms only a sine qua non for its ototoxicity. The mechanism of the ototoxicity should exist in the antibiotic-vulnerable cells (hair cells) themselves.