Coordination scheme and stereochemical configuration of manganese(II) adenosine 5'-diphosphate at the active site of 3-phosphoglycerate kinase

The structure of the MnIIADP complex at the active site of 3-phosphoglycerate kinase from yeast has been investigated by electron paramagnetic resonance (EPR) spectroscopy. Inhomogeneous broadening in the EPR signals for Mn(II) resulting from unresolved superhyperfine coupling to 17O regiospecifically incorporated into ADP shows that Mn(II) is coordinated to the alpha- and beta-phosphate groups of ADP at the active site of the enzyme. The EPR pattern for the enzyme-MnIIADP complex is characteristic of a predominantly axially symmetric zero-field splitting tensor. The symmetry and magnitude of the zero-field splitting interaction suggest that there is an additional negatively charged oxygen ligand in the coordination sphere of Mn(II). EPR measurements for solutions of the enzyme-MnIIADP complex in 17O-enriched water indicate that there are also two or three water molecules in the coordination sphere of the metal ion. EPR data for complexes with the two epimers of [alpha-17O]ADP have been used to determine the stereochemical configuration of the MnIIADP complex at the active site. EPR spectra for Mn(II) in the enzymic complex with (Rp)-[alpha-17O]ADP show an inhomogeneous broadening due to superhyperfine coupling with 17O whereas spectra for (Sp)-[alpha-17O]ADP complexes are indistinguishable from those for matched samples with unlabeled ADP. These results show that 3-phosphoglycerate kinase selectivity binds the alpha configuration of the alpha, beta chelate of MnIIADP. Addition of 3-phosphoglycerate to form the dead-end complex (enzyme-MnIIADP-3-phosphoglycerate) does not alter the EPR spectrum, but addition of vanadate to this complex causes marked changes in the spectral parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

1H nuclear magnetic resonance of heroin's D ring

The 1H nuclear magnetic resonance (NMR) chemical shifts and coupling constants of heroin's D ring H-15 alpha, H-15 beta, and H-16 alpha, and H-16 beta are presented. These assignments were accessible through the introduction of a double bond (delta 15,16) in heroin. The resulting compound, delta 15,16 didehydroheroin, was subjected to deuterium exchange or stereoselective reduction or both. Reduced products d1-16 alpha heroin d2-15 alpha, 15 beta-heroin, and d3-15 alpha, 15 beta, 16 alpha-heroin are presented. Heroin with deuterated acetyls is also presented for 1H NMR spectral clarity in the D ring area.

"Aggressive and socially disruptive behavior among maximum security psychiatric patients:" a perspective

The frequency of behavior or management problems for units of differing “security” within a maximum security hospital were compared. The frequency of such behaviors reflects a selection process more than the fact that the patients are in a “controlled treatment setting,” as suggested by the authors of a previous study.

A cloned cDNA probe for rat immunoglobulin epsilon heavy chain: construction, identification, and DNA sequence

IgE has clinical importance because it is responsible for immediate hypersensitivity. Studies of IgE expression in rats appear to contradict current models for immunoglobulin gene expression. To study rat IgE expression at the RNA and DNA levels, we have constructed a cDNA for part of the rat epsilon (epsilon) heavy chain that is expressed by a rat myeloma, IR162. The rat epsilon-chain clone was initially identified by an efficient selection scheme. DNA sequencing of the 580-bp cDNA revealed that it encoded 176 amino acids that were 50% homologous to the human epsilon H chain. The sequence begins near the end of the CH2 domain and ends 31 amino acids into the CH4 domain. Cysteines important for the structure of the human IgE were conserved in the rat epsilon H-chain. The identity of the cloned epsilon cDNA was confirmed by comparison with a portion of the constant region gene for mouse epsilon H chain. The mouse and rat nucleotide sequences were 79% homologous.

Physical and biological properties of an epsilon-heavy chain mRNA and a kappa-light chain mRNA coding for rat immunoglobulin E

The mRNA coding for epsilon-heavy chain and kappa-light chain have been highly enriched from a rat IgE-producing myeloma, IR-162. Based on denaturing gel analyses, the 20 S epsilon-heavy chain mRNA has an estimated molecular weight of 850,000, equivalent to about 2500 nucleotides. The 14S rat kappa-light chain mRNA has an estimated molecular weight of 410,000, equivalent to about 1200 nucleotides. Only about two-thirds of the length of these mature cytoplasmic rat mRNA code for protein. The 20 S mRNA stimulates the in vitro synthesis of a single major serologically related protein which is large enough to be epsilon-heavy chain. It is unglycosylated and has an apparent molecular weight of about 62,000. The in vivo unglycosylated epsilon-heavy chain, obtained in the presence of tunicamycin, has an apparent molecular weight of about 59,000, compared with about 76,000 for the glycosylated heavy chain of the secreted rat IgE. Therefore, the in vitro synthesized epsilon-heavy chain protein is about Mr = 3000 larger than the in vivo unglycosylated epsilon-heavy chain, equivalent to about 25 extra amino acids. This is consistent with the synthesis of an epsilon-heavy chain putative precursor. Likewise, the 14 S mRNA stimulates the in vitro synthesis of a single putative precursor protein, which is serologically related to kappa chain, is unglycosylated, and is about an extra 20 amino acids. This is the first report on the physical and biological properties of an epsilon-heavy chain mRNA, as well as any rat immunoglobulin mRNA.

Teratogenic effects of external egg applications of methyl mercury in the mallard, Anas platyrhynchos

The embryotoxic potential of external applications of methyl mercury on mallard eggs was investigated to assess the possible impact of mercury transferred from the plumage of effluent-contaminated aquatic birds to their eggs. Eggs were treated on day 3 of development with microliter applications of methyl mercury that was dissolved with ethyl acetate into an aliphatic hydrocarbon vehicle. Mercury analysis by atomic absorption indicated that almost half of the mercury applied entered the eggs past the shell membranes within several days of treatment. Most mortality occurred within this period at doses of 9 microgram of mercury per egg or higher. Decreased embryonic growth resulted with similar doses. A significant incidence of malformations occurred at a dose of 1 microgram per egg. These malformations were mainly minor skeletal aberrations and incomplete ossification. With higher doses of mercury, defects included gross external ones such as micromella, gastroschisis, and eye and brain defects. Application of the aliphatic hydrocarbon vehicle did not result in any of these defects.

Mouse immunoglobulin mu heavy chain mRNA of Y5781, a high yield myeloma

The BALB/c myeloma tumor, Y5781, has a high level of mu heavy chain mRNA and kappa light chain mRNA, as suggested by denaturing gel analyses of poly(A)-rich, total polysomal mRNA, and confirmed for the mu heavy chain mRNA by kinetic complexity analyses. Both the mRNA coding for the heavy and light chains appear as very prominent and discrete peaks above the generally polydisperse background of the total polysomal mRNA. This mRNA level appears to be stable through a limited number of subcutaneous passages of this myeloma, providing a potentially useful system for mu heavy chain mRNA synthesis and processing. The mu heavy chain mRNA of this myeloma has been enriched to about 60% homogeneity by physicochemical means. In agreement with a previous report (Faust, C.H., Jr., Heim, I., and Moore, J. (1979) Biochemistry 18, 1106-1119), the following physical and biological properties were observed. The mature cytoplasmic mu heavy chain mRNA is 950,000 daltons, i.e. about 2800 nucleotides, and contains approximately 800 undefined, nontranslated bases. In an mRNA-dependent cell-free system, this mRNA stimulates the synthesis of a single, serologically reactive mu heavy chain-like protein, confirmed by tryptic peptide maps.

Long-term follow-up of tympanic neurectomy for sialorrhea

Thirty-one patients who had undergone a bilateral tympanic neurectomy (sectioning of both Jacobson's nerve and the chorda tympani) for sialorrhea are evaluated after two years (ranging from 24--45 months). Drooling control improved in 74%. There was a significant difference of improvement in the group where a diligent search was made to sever all branches of the tympanic plexus. A 50% improvement was attained in two failures of a tympanic neurectomy who underwent transposition of Stenson's ducts into the tonsillar fossa.

Application of visual reinforcement audiometry (VRA) to low-functioning children

Visual reinforcement audiometry (VRA) was studied on a group of low-functioning children in an ongoing clinical program. After establishing the specific reinforcing value of the visual stimulus, threshold assessments were made. VRA was an effective test procedure for most of the children tested, providing their developmental ages reached approximately the 10-month level or higher. On the basis of VRA thresholds and tympanometry, 52% of the children seen were referred for medical evaluation. A variation of VRA was used to assess syllable-discrimination performance on a pilot basis. Results are discussed in terms of the potential use of VRA to assess infant spedch-sound discrimination in addition to its current use as an indicator of hearing sensitivity.

Visual reinforcement audiometry (VRA) with young Down's syndrome children

Visual Reinforcement Audiometry (VRA) was investigated with 41 Down's syndrome subjects between the ages of six months and six years. The VRA procedure involved monitoring a head-turn response to a complex noise signal presented in a sound field with an ascending presentation paradigm and reinforced by a complex visual reinforcer. Twenty-four of the infants and young children also were evaluated with the Bayley Scales of Infant Development (BSID) to allow for analysis of the efficacy of VRA as a function of developmental age. Results were as follows: (1) 28 (68%) of the infants and young children initially oriented towards the source of the auditory stimulus, (2) only a few of the subjects who did not initially orient could be taught to respond, (3) of the children who initially oriented or were taught to respond, thresholds were obtained on a large number (81%) in one visit, and (4) a systematic relationship was demonstrated between consistency of subject response using the VRA technique and BSID Mental Age Equivalent with 10 months being the critical age for determining the potential success of the procedure. In addition, the results implied a higher incidence of hearing loss in the Down's syndrome subjects than found in normal pediatric population.

Rapid and sensitive gas chromatographic quantitation of morphine codeine and O6-acetylmorphine in illicit heroin using an electron capture detector

Morphine, codeine and O6-acetylmorphine are reacted with heptafluorobutyric anhydride, rendering them suitable for electron capture detection and quantitation. The fluorinated derivatives are extracted from an acetonitrile-sodium bicarbonate solution into light petroleum in a rapid one-step extraction procedure. The derivatives are chromatographed on a stationary phase of 3% OV-17 on Gas-Chrom Q. Morphine, codeine and O6-acetylmorphine can be readily quantitated in heroin at levels as low as 0.001%, 0.01% and 0.01% respectively. Reproducibility, linearity and recovery studies are described.

Developmental changes in speech discrimination in infants

A visually reinforced infant speech discrimination (VRISD) paradigm is described and evaluated. Infants at two ages were tested with the new paradigm on the following speech contrasts: [sa] vs [va], [sa] vs [fa], [sa] VS [za], [as] vs [a:s], vs [a:z], [at] vs [a:d], [a:t] vs [a:d], [at] vs [a:t], [fa] vs [thetaa]and [fi] vs [thetai]. The data reported are compared with data on the same speech contrasts obtained from three month olds in a high-amplitude sucking paradigm. Evidence suggesting developmental changes in speech-sound discriminatory ability is reported. Results are interpreted in light of salience of available acoustic cues and in terms of new methodological advances.

Visual reinforcement of head-turn responses in infants under 12 months of age

The effect of complex visual reinforcement (animated toy animal) on auditory localization responses of infants below 12 months of age was studied. Sixty infants served as subjects and each subject received 30 presentations of complex noise at suprathreshold level. After each response to an auditory signal, one-half of the infants (experimental group) received complex visual reinforcement and the other half (control group) received no reinforcement. The experimental and control groups were further subdivided into three age groups: four months, five and six months, and seven to 11 months. Visual reinforcement produced significantly more responses (head turn) than no reinforcement for the two older age groups. There was no significant difference between the experimental and control conditions at four months of age.

Auditory localization of infants as a function of reinforcement conditions

The influence of four reinforcement conditions on the auditory localization behavior of normal infants was studied. Forty-eight infants 12 to 18 months of age were assigned to one of four groups of 12 subjects each. All received 30 presentations of complex noise at suprathreshold level. After each response to the stimulus, Group 1 received no reinforcement, Group 2 received social reinforcement, Group 3 received "simple" visual reinforcement (a blinking light), and Group 4 received "complex" visual reinforcement (an animated toy animal). The two visual reinforcement conditions produced the most localization responses, followed in order by the social reinforcement and no reinforcement conditions. These results indicate that auditory localization behavior of infants is influenced by reinforcement and that the extent of this effect is related to the type of reinforcement employed.