Evidence for glutamate as a neurotransmitter in the cat vestibular nerve: radioautographic and biochemical studies

Evidence that glutamate acts as a neurotransmitter in vestibular nerve fibers was sought (1) by electron microscope radioautographic identification of the uptake sites of [3H]-glutamic acid after incubation of slices of cat vestibular nuclei, and (2) by measuring changes in sodium-dependent high affinity glutamate uptake in nerve endings containing homogenates from normal and deafferented vestibular nuclei 8 to 11 days after unilateral vestibular nerve lesion. Electron microscopic radioautography revealed that glutamate had been taken up by numerous nerve endings projecting over the whole vestibular nuclear complex. The biochemical approach indicated that after section of the vestibular nerve, a significant decrease in high affinity glutamate uptake occurred in the vestibular nuclei, which lost their exclusively ipsilateral projection. This decrease varied from one area of the deafferented vestibular nuclei to another, reaching -58% in the lateral area of the central part corresponding to the ventral lateral vestibular nucleus and the rostral part of the descending vestibular nucleus. It is concluded that glutamate (or aspartate) is used by the vestibular nerve fibers as a neurotransmitter in the vestibular nuclei.

Comparative study of three methods of resuscitation: closed-chest, open-chest manual, and direct mechanical ventricular assistance

Presented are the results of a comparison study of three forms of circulatory support during ventricular fibrillation: closed-chest compression (CCC), open-chest manual compression (OCMC), and direct mechanical ventricular assistance (DMVA). DMVA is a method of circulatory support using a bell-shaped device that is affixed to the heart by apical suction and that alternately compresses and expands the ventricles. CCC produced a cardiac index (CI) of 780 mL/min/m2 (19% of control) with a mean arterial pressure (MAP) of 26 mm Hg (23% of control). Both forms of direct cardiac compression produced higher values. OCMC at 60 compressions per minute (CPM) produced a CI of 2,069 mL/min/m2 (52% of control) with an MAP of 50 mm Hg (45% of control). DMVA at the same rate produced a CI of 2,780 mL/min/m2 (70% of control) with an MAP of 72 mm Hg (65% of control). The values for DMVA at 60 CPM were significantly higher than for OCMC at 60 CPM (P less than .005 for CI, and P less than .0005 for MAP). Changing from standard CCC to DMVA at 90 CPM produced the greatest hemodynamic improvements: MAP increased by 250%, and CI increased by 340%. With DMVA at 90 CPM, the systolic pressure, stroke index, and CI were not statistically different from control, prearrest values.

Nuclear imaging as a screening test for patients referred for intraarticular facet block

Our experience, in a group of 25 patients with chronic low back pain, shows that nuclear imaging of the spine with 99mTc-methylene diphosphonate is of no benefit in predicting the sites at which intraarticular facet blocks may be successful.

Selective retrograde labeling of neurons of the cat vestibular ganglion with [3H]D-aspartate

D-[2,3-3H]Aspartate [( 3H]D-Asp) was injected in the cat vestibular nuclei. Labeling patterns resulting from retrograde axonal transport by the vestibular nerve fibers were observed in the vestibular ganglion neurons and also in the nerve fibers. The selectivity of such labeling, related to the neurotransmitter's specificity, is strongly indicated.

Nutrition for the first Total Artificial Heart patient: implications for future patients

Since the mid-1960s, millions of dollars in federal funds have been used for research in the development of the Total Artificial Heart (TAH). Significant advances in bio-materials and pump and energy systems, as well as animal experimentations, have led to the clinical reality of the TAH's use in man. On December 2, 1982, Dr. Barney Clark became the first recipient of a permanent TAH. He had been suffering from terminal congestive heart failure secondary to idiopathic cardiomyopathy. No other treatment was available, since, at the age of 61, he was too old for heart transplant. Dr. Clark's 112-day hospitalization was complicated by pulmonary problems, renal insufficiency, seizures, nosebleeds, and a broken heart valve. Dr. Clark appeared malnourished before surgery, and his numerous postoperative complications confounded attempts at nutritional support. Standard nutritional assessment techniques were inadequate or inappropriate in the face of severe edema, renal failure, and multiple transfusions. Although nitrogen balance was achieved intermittently, for the majority of his hospitalization Dr. Clark remained in negative nitrogen balance, due mainly to renal insufficiency. Some of the nutritional complications seen in the first TAH patient might have been preventable with early nutritional assessment and more aggressive support. The Artificial Heart Management Team at the University of Utah now includes a nutritionist, and future protocols outline detailed nutrition monitoring.

Intraarticular facet block: diagnostic test or therapeutic procedure?

The specificity of the intraarticular facet block as a diagnostic test for facet joint disease is currently unknown. Capsular rupture with epidural and periarticular diffusion is probably responsible for many false positive findings. We found a comparatively low success rate of the procedure in 25 patients in whom maximal volumes were strictly controlled to avoid extravasation.

The efferent vestibular system in the cat: a horseradish peroxidase and fluorescent retrograde tracers study

Neurons of the efferent vestibular system were investigated in the cat using retrograde axonal transport of horseradish peroxidase and fluorescent retrograde double labelling techniques. The number of efferent neurons was clearly higher than previously reported. A three dimensional reconstruction of the location of these neurons showed that they constitute a single group and did not give evidence of an eventual specialization based on neuron subpopulations. However, a study of cross-sectional areas of the horseradish peroxidase-labelled efferent neurons detected that the ipsilateral population contained a larger number of small neurons than the contralateral one. Double labelling by means of either 4',6-diamidino-2- phenylindol 2HCl in combination with horseradish peroxidase or Fast Blue in combination with Nuclear Yellow showed that 20% of efferent neurons project to both labyrinths. Such a high percentage raises the question of the role of these double-projecting cells and the specificity of their branching on vestibular receptors. This study expands previous work in the cat demonstrating that a much greater number of efferent neurons exists than had hitherto been assumed, among them 20% have both crossed and uncrossed projections.

Action of glutamate in the cat labyrinth

Glutamate solutions of either 50 mM applied on the membranous labyrinth or 1 mM perfused into the lateral canal in cats increased spontaneous and stimulus-evoked activity of vestibular neurons. Kainic acid (10(-4) M) perfused into the labyrinth produced a depolarizing action on vestibular afferents. These results indicate that glutamate could be an excitatory neurotransmitter at the synapse between vestibular hair cells and afferent nerve fibers in the cat.

Efferent innervation of vestibular receptors in the cat: a radioautographic visualization

A tritiated amino acid tracing method was used to test the hypothesis that a unilateral group of vestibular efferent neurons of the brain stem may present different innervation patterns to the sensory vestibular epithelia of the ipsi- and contralateral labyrinths. Densitometric analysis of labeled efferent endings suggested a heterogeneity of the efferent projections issuing from a unilateral predominated in the maculae utriculi and cristae ampullares of the semicircular canals. These findings are discussed as a function of other data related to efferent vestibular control.

The cecal diaphragm

A detailed radiologic, colonoscopic, and histologic analysis is described in the case of a cecal web presenting as a "cecal mass." The demonstration of a transverse band-like lucency proximal to the ileocecal valve should prompt careful double-contrast barium studies, to which endoscopy may be added, enabling a correct diagnosis to be made.

Selective retrograde labelling of vestibular efferent neurons with [3H]choline

Following administration of [3H]choline in the lateral semicircular canal of the cat labyrinth, bidirectional axoplasmic transport [3H]choline and its derivatives was shown by radioautography in the vestibular system. Light-microscopic radioautographs exhibited various patterns of radioautographic labelling. First, a diffuse reaction was observed in vestibular nuclei representing anterograde-labelled, vestibular nerve endings. Second, a heavy labelling limited to perikarya was detected in efferent vestibular neurons and corresponded to retrograde transport. The anterograde migration of [3H]choline is known to be non-selective and is related to synthesis of phospholipids, non-diffusable molecules. In contrast, the retrograde perikaryal labelling seems highly selective and related to the cholinergic specificity of the transmitter. The selectivity of such labelling offers a further possibility of identifying cholinergic neurons and is additional evidence that cholinergic mechanisms are involved in the efferent vestibular control.

Use of the enzyme-linked immunosorbent assay for detection of antibodies to Chlamydia trachomatis

An enzyme-linked immunosorbent assay (ELISA) using a soluble antigen prepared from the D strain of Chlamydia trachomatis was used for titration of IgG antibodies to Chlamydia trachomatis in 153 sera from 126 patients with non-specific genital infection and from 27 healthy subjects. The results were compared to those obtained with the micro-immunofluorescence method and were in complete agreement in 143 of the 153 sera. The ELISA proved to be reproducible and as sensitive as the micro-immunofluorescence method.

Changes in serum amylase and its isoenzymes after whole body irradiation

A study was carried out to assess the effect of total body irradiation on pancreatic and parotid isoenzymes of amylase in patients about to undergo bone-marrow transplantation who had received high-dose cyclophosphamide. Twelve patients were studied, enzyme activity being measured before and at various times after total body irradiation. Serum total amylase activity rose rapidly within 12 hours of irradiation to a maximum at 36 hours, returning to normal by six days; most of the increase was derived from salivary damage, with a much smaller pancreatic component. These results confirm that radiation produces acute changes in amylase activity, which may be of use in assessing radiation-induced damage.

[In vitro organotypic development of the vestibular sensory epithelium of the embryonic mouse otocyst. A morphological and autoradiographic study (author's transl)]

The cytogenesis of the two cell populations of the vestibular sensory epithelium-hair cells and supporting cells-was investigated in explanted Mouse embryo otocysts using tritiated thymidine autoradiography. The otocysts were explanted on the 13th day of gestation and grown in vitro for 7 days. A close in vitro and in vivo correspondence was found in the cytodifferentiation of the sensory epithelium. At different times after explanation, a single administration of tritiated thymidine was added to the otocysts. The time schedule of the hair cell generation in the explants was essentially different from that observed during normal development. In contrast, the time schedule of the supporting cell generation was only mildly altered. The data suggest that the generative processes of the two cell populations are influenced differently, depending on their later specific differentiation.

Radioautographic identification of [3H]glutamic acid labeled nerve endings in the cat oculomotor nucleus

Slices of the cat third oculomotor nucleus were incubated in vitro with [3H]glutamic acid. Electron microscopic radioautographs revealed that glutamate had been taken by small nerve endings distributed on the oculomotor motoneuron distal dendrites. In contrast, there was no uptake in the other types of terminals. The labeled terminals seem to correspond to the excitatory vestibulo-oculomotor nerve endings and different correlations suggest their glutamergic nature.

Formation of intercellular collagen matrix by cultured liver epithelial cells and loss of its ability in hepatocarcinogenesis in vitro

Epithelial cells of normal rat liver origin (strain RL34) synthesized the alpha 1 peptide of type I collagen. In nononcogenic cultures (RL34 and RL34EC) and a marginally oncogenic culture (RL34HII), the peptide was continuously secreted from the proliferating cells. Part of the soluble peptide was incorporated into the intercellular matrix of contact-inhibited cells after confluency, while the remainder was degraded. The intercellular matrix contained characteristic collagen fibrils which were argyrophilic and revealed a 64 nm axial periodicity. Epithelial cells of an oncogenic culture (RL34HT) secreted procollagen into the medium continuously throughout their proliferative phases and were unable to accumulate collagen fibrils in the intercellular matrix. The depletion of collagen accumulation in the hepatocarcinoma cell culture was ascribed to lack of the binding of native collagen molecules to the cell membrane and the persistence of high proteolytic activity on the cell surface.

Abnormal adaptation of visual contrast sensitivity in multiple sclerosis patients

Some multiple sclerosis patients with 20/20 acuity complain of poor vision. In a previous report we accounted for this in our patient group by showing that multiple sclerosis had caused a depression of contrast sensitivity while sparing visual acuity. In this study we investigated whether some of this measured depression might be due to abnormally rapid or severe adaptation during the test procedure rather than a true permanent loss. Our finding was opposite to this supposition: adaptation was normally slight and/or slow. Depressed contrast sensitivity was not well correlated with abnormal adaptation to contrast. In patients whose contrast sensitivity losses were restricted to a band of spatial frequencies, we found no evidence that abnormalities of contrast adaptation were restricted to this same spatial frequency band. Further evidence of dissociation between abnormal contrast sensitivity and abnormal contrast adaptation is that some patients with normal contrast sensitivity showed abnormally small adaptation.