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Biomedical subjects

D Deutsch

Publications and source records attributed to D Deutsch.

At least 37 records · Page 2Linked to original sources
PubMed1993

Racemization of aspartic acid in the extracellular matrix proteins of primary and secondary dentin.

The accumulation with age of D-aspartic acid in primary and secondary human dentin was determined. In primary dentin, the plot of the D/L Asp ratio vs. age was found to fit first-order kinetics in accordance with the literature. But the secondary dentin behaved in an irregular manner and showed, in the great majority of cases, significantly increased D/L Asp ratios. Possible reasons for these findings, such as differences in protein composition and/or in the prevailing temperature, are discussed.

Adolescent↗
PubMed1993

Amino acid sequence of a major human amelogenin protein employing Edman degradation and cDNA sequencing.

The abundant hydrophobic, proline-glutamine, and histidine-rich (over 90%) amelogenins constitute the major class of proteins in forming extracellular enamel matrix. These are thought to play a major role in the structural organization and mineralization of developing enamel. The present report describes the successful sequencing of the major human amelogenin protein, by use of both Edman degradation and cDNA sequencing. When Edman degradation was used, over 75% of the primary structure of the protein was determined. This sequence was supplemented with cDNA sequencing studies, which revealed the predicted sequence of this protein. Together, they provide the complete sequence of an important human enamel protein. The information complements recent studies on bovine and human amelogenin genes. A comparison between the present results and the protein sequences predicted from the corresponding human amelogenin genomic coding regions and that of cDNA sequences of other species is described.

Amelogenin↗
PubMed1992

Some new pitch paradoxes and their implications.

This paper explores two new paradoxical sound patterns. The tones used to produce these patterns consist of six octave-related harmonics, whose amplitudes are scaled by a bell-shaped spectral envelope; these tones are clearly defined in terms of pitch class (C, C#, D, and so on) but are poorly defined in terms of height. One pattern consists of two tones that are separated by a half-octave. It is heard as ascending when played in one key, yet as descending when played in a different key. Further, when the pattern is played in any one key it is heard as ascending by some listeners but as descending by others (the tritone paradox). Another pattern that consists of simultaneous pairs of tones displays related properties (the semitone paradox). It is shown that the way the tritone paradox is perceived correlates with the speech characteristics of the listener, including his or her linguistic dialect. The findings suggest that the same, culturally acquired representation of pitch classes influences both speech production and also perception of this musical pattern.

Acoustic Stimulation↗
PubMed1992

Effect of the ArF excimer laser on human enamel.

Human enamel surface was irradiated with ArF excimer laser and examined under light microscopy and scanning electron microscopy (SEM). Enamel surface was irradiated at three different areas with different energy fluences. It is demonstrated that the ArF excimer laser causes ablation of the calcified hard enamel tissue. Ablation curves were measured. There was no significant difference found in the etch depth between the three different areas of enamel surface. The morphology of the irradiated areas seen under the SEM was found to be dependent on energy fluence. It changed with increase in energy fluence from being etched to forming a smooth, fused, glaze-like surface and then at very high energy fluences producing a rough surface. The influence of the laser irradiation was confined to the irradiated area only, with no visible heat damage to the surroundings. These results suggest that excimer laser could be applied in a controlled and defined manner for tooth enamel treatments in dentistry.

Dental Enamel↗
PubMed1991

Sequencing of bovine enamelin ("tuftelin") a novel acidic enamel protein.

Enamelins are a major group of 28-70-kDa acidic proteins rich in aspartic acid, glutamic acid, serine, and glycine found in developing and mature extracellular enamel; a unique and highly mineralized ectodermal tissue covering vertebrate teeth. They have been associated with the mineralization and structural organization of this tissue. In an attempt to elucidate the primary structure of enamelin, a 2674-base pair cDNA isolated from a bovine ameloblast-enriched, lambda Zap 2 expression library, was sequenced. The identity and localization of the deduced protein was confirmed by amino acid composition, enzyme-linked immunosorbent assay, Western blotting, indirect immunohistochemistry, and high resolution protein-A gold immunocytochemistry. The immunological techniques were employed using antibodies directed against synthetic peptides corresponding to the protein sequence deduced from the cloned cDNA sequence. The results reveal the deduced protein to be a novel acidic enamel protein. It contains 389 amino acids and has a calculated molecular weight of 43,814. Its amino acid composition is similar to that of "tuft" proteins (enamel matrix protein fragments remaining in the mature tissue). It contains one potential N-glycosylation site and 5 cysteine residues. Southern hybridization of the cloned cDNA with genomic bovine DNA indicated the existence of a single gene with one or more introns.

Amino Acid Sequence↗
PubMed1991

Carbonate content in developing human and bovine enamel.

The present study describes the detailed changes in carbonate distribution throughout the different stages of development in human and bovine enamel, from early formation to maturation. Twenty-two human maxillary and mandibular deciduous anterior teeth and 46 bovine teeth were studied. The major mineral ions, calcium and phosphorus, were also analyzed to facilitate comparison of carbonate content with progressing mineralization. The results showed that as enamel matured and mineral concentration increased, carbonate concentration decreased. The observed decrease in percent carbonate per weight enamel mineral may be due to dilution by an influx of relatively carbonate-free mineral, and could, in part, explain the observed increase in crystallinity of enamel mineral as the tissue matures.

Aging↗
PubMed1991

Effect of I-Scrub on signs and symptoms of chronic blepharitis.

To assess the effect of I-Scrub (Spectra Pharmaceutical Services), a new detergent eyelid scrub, on the subjective symptoms and objective clinical signs of chronic blepharitis, 20 patients with this disease were treated for three weeks. None of them yielded positive cultures for virulent bacteria from the eyelids and conjunctiva. Most of the patients reported significant reduction in the subjective symptoms and in the severity of the clinical signs as well. No adverse effects were observed. The results of our study suggest that this product is of value as a detergent eyelid scrub in the treatment of chronic blepharitis.

Aged↗
PubMed1990

Thermal decomposition of developing enamel.

The decomposition of forming, maturing, and mature enamel was studied between room temperature and 1,000 degrees C by powder X-ray diffraction and infrared absorption methods. In mature dental enamel, carbonate decomposition proceeds relatively fast until 500 degrees C and at a slower rate beyond it. In forming and maturing enamel, decomposition is faster and is completed around 800 degrees C. The formation of beta-Ca3(PO4)2 is observed in dental enamel at 500 degrees C. At 1,000 degrees C, the apatite phase in forming and maturing enamel transforms almost completely to beta-Ca3(PO4)2, whereas in mature enamel, even at 1,000 degrees C, only partial decomposition occurs. Infrared results show the appearance in dental enamel of (1) A-type carbonate at room temperature and in the 500-900 degrees C range, in addition to the commonly observed B-type carbonate, and (2) intermediate CO2 molecules during carbonate decomposition (200-500 degrees C).

Animals↗
PubMed1989

[Epiphora as an expression of dry eye].

One of the most common ophthalmic disorders in the elderly is epiphora, a watery eye with overflow of tears. In some patients it appears in a paradoxical form: dry eye indoors and tearing outdoors. We present a 76-year-old man and a 58-year-old woman with this disorder. Despite diagnosis of dry eye, confirmed by several tests, they complained of epiphora. This ceased after treatment with tear substitutes, bromhexine and occlusion of the lacrimal puncti. The possibility that tearing may be an expression of the dry eye state should always be considered.

Aged↗
PubMed1989

Structure and function of enamel gene products.

The present paper reviews the main features of amelogenin and enamelin biochemistry, molecular biology, structural and ultrastructural localization, and immunology. It also examines recent studies concerning the origin, chemical characterization, suggested role, and participation of these two major classes of extracellular developing enamel matrix proteins in the complex process of "matrix-mediated" mineralization.

Amelogenin↗
PubMed1989

Endogenous candidal endophthalmitis.

The incidence of systemic mycotic infections, though formerly rare, has increased dramatically over the past two decades. Candida albicans has been recognized as the most common pathogen in endogenous fungal endophthalmitis. Accurate antemortem diagnosis of disseminated candidiasis is made, however, only in a few cases. Ocular findings may often provide the first definitive clue to an underlying mycotic infection. We present four cases of candidal endophthalmitis; in each the ophthalmologist played a major role in the early diagnosis of the underlying systemic infection, allowing specific therapeutic measures to be taken. We also discuss the common predisposing factors, ocular symptoms and findings, clinical course, and response to antifungal therapy.

Aged↗
PubMed1988

Lateralization and sequential relationships in the octave illusion.

Subjects made lateralization judgments concerning sequences of dichotic chords whose components stood in octave relation. In condition 1, each ear received a sequence consisting of 400- and 800-Hz tones in alternation, such that when one ear received the 400-Hz tone, the other ear simultaneously received the 800-Hz tone. Condition 2 was identical to condition 1, except that the alternating tones were at 600 and 1200 Hz instead. In condition 3, dichotic chords at 400 and 800 Hz alternated with dichotic chords at 600 and 1200 Hz. In all conditions, the amplitude relationships between the higher and lower tones were varied, and the percent lateralization to the higher frequency signal was plotted as a function of these amplitude relationships. In all conditions, when the tones at the two ears were equal in amplitude, lateralization tended to be toward the ear receiving the higher frequency signal. Averaged across subjects, this tendency in condition 1 was overcome only when the lower frequency signal was 12 dB higher in amplitude, and, in condition 2, when it was 9 dB higher. However, in condition 3, the tendency was overcome when the lower frequency signal was 3 dB higher in amplitude. The lateralization effect was thus shown to be influenced by the sequential relationships between the frequencies presented to the two ears.

Functional Laterality↗