Effect of denervation on the neuron-specific enolase immunoreactivity of Merkel cells in the taste organs of the frog.

The changes in neuron-specific enolase (NSE) immunoreactivity of Merkel cells in the frog taste organ were investigated up to 5 months after resection of the glossopharyngeal nerve. Even at 5 months after denervation, the denervated Merkel cells exhibited an immunoreaction with NSE antiserum.

Morphological changes of taste buds and fungiform papillae following long-term neurectomy.

Long-term neurectomy of chorda tympani-lingual nerves results in a complete disappearance of taste buds from rabbit fungiform papillae. This supports the view that taste buds of mammalian fungiform papillae are neurally dependent. Furthermore, the covering epithelium of denervated fungiform papillae develops a characteristic keratinization pattern corresponding to that of filiform papillae.

Intact text-specific reading skill in amnesia.

Amnesic patients were studied to determine whether the acquisition and retention of item-specific skills can be supported by nondeclarative (implicit) memory. In Experiment 1, subjects read 2 different passages 3 times in succession. Reading speed improved at a similar rate in both amnesic patients and normal subjects and was specific to the text that was read.

Memory for the temporal order of events in patients with frontal lobe lesions and amnesic patients.

Patients with frontal lobe lesions, amnesic patients with Korsakoff's syndrome, other (non-Korsakoff) amnesic patients, and control subjects were given tests of memory for temporal order. In the first experiment, subjects were presented with a list of 15 words and then asked to reproduce the list order from a random array of the words. In the second experiment, they were asked to arrange in chronological order a random display of 15 factual events that occurred between 1941 and 1985.

Histone H1 represses transcription from minichromosomes assembled in vitro.

We have previously shown that transcription from a Xenopus 5S rRNA gene assembled into chromatin in vitro can be repressed in the absence of histone H1 at high nucleosome densities (one nucleosome per 160 base pairs of DNA) (A. Shimamura, D. Tremethick, and A.

Assembly and properties of chromatin containing histone H1.

The Xenopus oocyte supernatant (oocyte S-150) forms chromatin in a reaction that is affected by temperature and by the concentration of ATP and Mg. Under optimal conditions at 27 degrees C, relaxed DNA plasmids are efficiently assembled into supercoiled minichromosomes with the endogenous histones H3, H4, H2A and H2B. This assembly reaction is a gradual process that takes four to six hours for completion.

The assembly of regularly spaced nucleosomes in the Xenopus oocyte S-150 extract is accompanied by deacetylation of histone H4.

Histone proteins, which were assembled into chromatin using the Xenopus oocyte S-150 extract, were analyzed on acid-urea gels and Triton-acid-urea gels to determine their state of modification. We find that histone H4, which is present in a diacetylated form in the oocyte S-150, gradually loses its acetate groups as the DNA is packaged into chromatin. Thus, this process parallels the one observed in vivo during chromatin formation in growing eucaryotic cells.

Purification and characterization of cell-associated glucosyltransferase synthesizing insoluble glucan from Streptococcus mutans serotype c.

Streptococcus mutans Ingbritt (serotype c) was shown to have a significant amount of cell-associated glucosyltransferase activity which synthesizes water-insoluble glucan from sucrose. The enzyme was extracted from the washed cells with SDS, renatured with Triton X-100, adsorbed to 1,3-alpha-D-glucan gel, and then eluted with SDS. The enzyme preparation was electrophoretically homogeneous, and the specific activity was 7.

Impaired priming of new associations in amnesia.

We assessed priming of new associations in amnesic patients and healthy control subjects in a paradigm developed by Graf and Schacter (1985). Subjects were presented unrelated word pairs embedded in sentences (e.g.

Cognitive impairment following frontal lobe damage and its relevance to human amnesia.

Whether frontal lobe pathology can account for some of the cognitive impairment observed in amnesic patients with Korsakoff's syndrome was investigated. Various cognitive and memory tests were given to patients with circumscribed frontal lobe lesions, patients with Korsakoff's syndrome, non-Korsakoff amnesic patients, and control Ss. Patients with frontal lobe lesions were not amnesic.

The neurology of memory: quantitative assessment of retrograde amnesia in two groups of amnesic patients.

The phenomenon of retrograde amnesia has important implications for understanding normal memory as well as its neural organization. Using 6 tests of remote memory, we evaluated the extent and severity of retrograde amnesia in 2 groups of amnesic patients--7 patients with alcoholic Korsakoff's syndrome and 5 other patients with amnesia (anoxia or ischemia, N = 3; thalamic infarction, N = 1; unknown etiology, N = 1). Although there were individual differences, Experiment 1 showed that the severity and extent of retrograde amnesia was similar for the 2 groups.

Scanning electron microscopic study on the lingual papillae of the Japanese insectivora.

The tongue and lingual papillae of the Japanese Insectivora, the Shinto shrew (Sorex caecuiens saevus), the long-clawed shrew (S. unguiculatus), the dsinezumi shrew (Crocidura dsinezumi dsinezumi) and the Japanese water shrew (Chimarrogale himalyica platycephala), were observed by scanning electron microscope. The tongue of these animals had two vallate papillae.

Purification and characterization of extracellular glucosyltransferase synthesizing water-insoluble glucan from Streptococcus rattus.

An extracellular glucosyltransferase synthesizing water-insoluble glucan (GTF-I) was purified from the culture supernatant of Streptococcus rattus strain BHT (mutans serotype b) by hydroxylapatite chromatography, DEAE-Toyopearl chromatography and preparative isoelectric focusing. The Mr of GTF-I was 155,000 by SDS-PAGE and the isoelectric point was pH 4.9.

Use of 13C-n.m.r. spectroscopy for the quantitative estimation of 3-O- and 3,6-di-O-substituted D-glucopyranosyl residues in alpha-D-glucans formed by the D-glucosyltransferases of Streptococcus sobrinus.

The 13C-n.m.r.

Source memory impairment in patients with frontal lobe lesions.

In two experiments, we investigated memory for recently learned facts and memory for the source of the facts (i.e. where and when the facts were learned) in patients with frontal lobe lesions, age-matched elderly control subjects, and younger subjects.

Korsakoff's syndrome: radiological (CT) findings and neuropsychological correlates.

Quantitative analyses were performed on computer tomography (CT) scans from 7 patients with Korsakoff's syndrome, 7 age-matched alcoholic subjects, and 7 age-matched healthy control subjects. CT values were used to estimate tissue density and fluid volume in specified brain areas. Tissue density was assessed by averaging CT values in small (5 x 5 mm) areas sampled bilaterally in 6 specified areas--thalamus, head of the caudate nucleus, putamen, anterior white matter, posterior white matter, and centrum semiovale.

Characterization of the repressed 5S DNA minichromosomes assembled in vitro with a high-speed supernatant of Xenopus laevis oocytes.

We describe an in vitro system, based on the Xenopus laevis oocyte supernatant of Glikin et al. (G. Glikin, I.

Long-term memory in amnesia: cued recall, recognition memory, and confidence ratings.

We explored what kind of information is acquired when amnesic patients are able to exhibit significant retention on tests of cued recall and recognition memory. Amnesic patients and control subjects attempted to learn sets of sentences. Memory for the last word in each sentence was tested after 1 hr in the case of the amnesic patients, or after 1 to 2 weeks in the case of (delayed) control subjects.

Streptococcus mutans gtfA gene specifies sucrose phosphorylase.

The ethanol-insoluble product formed from sucrose by purified enzyme encoded by the gtfA gene from Streptococcus mutans, expressed in recombinant Escherichia coli, was analyzed by 13C and 31P nuclear magnetic resonance. The product was identified as alpha-D-glucose-1-phosphate, and it was concluded that the GTF-A enzyme is sucrose phosphorylase (sucrose:orthophosphate alpha-D-glucosyltransferase [EC 2.4.

Lexical and semantic priming deficits in patients with Alzheimer's disease.

Two experiments utilizing priming procedures examined the status of semantic memory in demented and amnesic patients. In the first investigation, lexical priming was assessed in patients with dementia of the Alzheimer type (DAT), Huntington's Disease (HD), alcoholic Korsakoff's syndrome (KS), and in intact control subjects. Subjects were first exposed to a list of words in a rating task and then required to complete three-letter stems with the "first word that comes to mind".

An immunohistochemical demonstration of neuron-specific enolase in the Merkel cells of the frog taste organ.

The Merkel cells in the taste organ of the frog were investigated by immunohistochemistry using neuron-specific enolase (NSE) antiserum. NSE-immunoreactivity was found exclusively in the Merkel cells lying at the base of the taste organ. The distribution and the profiles of the NSE-immunoreactive Merkel cells coincided with serotonin-containing cells previously reported at the same place.

Merkel-neurite complexes in the fungiform papillae of two species of monkeys.

Merkel-neurite complexes in tongues of Japanese and cynomolgus monkeys were examined by means of light and electron microscopy. Merkel-neurite complexes were found preferentially in the epithelium of fungiform papillae located at the tip of the tongue. It appears that the anterior fungiform papillae of the monkey are highly adapted for both taste and mechanical sensation.