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Biomedical subjects

P Greene

Publications and source records attributed to P Greene.

At least 55 records · Page 3Linked to original sources
PubMed1990

Paroxysmal kinesigenic dystonic choreoathetosis associated with a thalamic infarct.

We describe a patient with the development of paroxysmal kinesigenic dystonic choreoathetosis (PKDC) after a thalamic infarct. PKDC consists of brief episodes of dystonia or choreoathetosis triggered by movement. PKDC improves with anticonvulsants, and in some cases, with L-Dopa or anticholinergics. We review PKDC, and relate its salient features to idiopathic and secondary torsion dystonia. We postulate a similar underlying pathophysiology.

Athetosis↗
PubMed1990

Double-blind, placebo-controlled trial of botulinum toxin injections for the treatment of spasmodic torticollis.

We enrolled 55 patients in a double-blind, placebo-controlled, parallel design study of the effectiveness of botulinum toxin (Botox) injections for the treatment of spasmodic torticollis. Patients received a standard series of injections, either placebo or Botox. We determined the sites of injection and dose per muscle by the nature of head deviation. Compared with placebo, Botox produced statistically significant improvement in the severity of torticollis, disability, pain, and degree of head turning. There were no serious side effects. During the double-blind phase, 61% of patients injected with Botox improved; 74% of patients subsequently improved during a later open phase at a higher dose of Botox. Direction of head turning, severity of torticollis, and presence or absence of jerky movements did not significantly influence the response rate. We conclude that Botox is a valuable treatment for spasmodic torticollis.

Analysis of Variance↗
PubMed1989

Environmentally induced conformational changes in B-type DNA: comparison of the conformation of the oligonucleotide d(TCGCGAATTCGCG) in solution and in its crystalline complex with the restriction nuclease EcoRI.

Raman spectroscopic analysis of the secondary structure of the crystalline restriction endonuclease EcoRI, the oligonucleotide d(TCGCGAATTCGCG) in solution, and the corresponding crystalline EcoRI-oligonucleotide complex reveals structural differences between the complexed and uncomplexed protein and oligonucleotide components that appear to be linked to complex formation. Structural differences that are spectroscopically identified include (1) an increase in the population of furanose rings adopting the C3'-endo conformation and (2) spectroscopically observed changes in base stacking which are probably associated with the crystallographically observed distortion of the phosphate backbone about positions C(3)-G(4) and C(9)-G(10) and unwinding between the symmetry-related segments GAA-TTC which make up the central recognition core (McClarin et al., 1986). Changes in base stacking due to distortions and unwinding along the oligonucleotide result in differences in the base vibrational region between the spectra of the complex and the oligonucleotide in solution. The spectroscopic analysis indicates that the C2'-endo population is similar for the oligonucleotide in solution and in the complex. The additional C3'-endo population in the complex appears to arise from the conversion of rings adopting alternative conformations such as C1'-exo and O1'-endo. Analysis of the vibrational bands derived from guanine indicates that the population of guanine residues associated with furanose rings in a C2'-endo conformation is similar for the oligonucleotide in solution and in the crystalline complex. This implies that the increase in C3'-endo population is not associated with guanine residues. Large conformational distortions such as those observed in the crystal distortions are not observed in either the crystal or the solution of the oligomer d(CGCGAATTCGCG).(ABSTRACT TRUNCATED AT 250 WORDS)

Crystallography↗
PubMed1989

Contextual conditioning and the control of copulatory behavior by species-specific sign stimuli in male Japanese quail.

Three experiments were conducted to identify species-specific sign stimuli sufficient to elicit copulatory behavior in male Japanese quail and to determine how learning is involved in the control of behavior by these sign stimuli. In Experiment 1, sexually experienced subjects were tested for copulatory behavior with a live female quail and with a model consisting of a female quail's head and neck mounted in front of a foam pad. Comparable levels of copulatory behavior were observed in the two tests, indicating that static visual cues provided by a female quail's head and neck are sufficient to elicit copulatory behavior in this species. Experiment 2 showed that male birds that previously received numerous opportunities to copulate with a live female quail in the test situation were significantly more likely to copulate with the head + neck model than were sexually inexperienced subjects. Experiment 3 showed that prior sexual experience with live quail facilitated responding to the head + neck model only if the sexual experience was provided in the same place where subjects were later tested with the model. This last finding suggests that sexual experience facilitates control of copulatory behavior by species-specific sign stimuli through contextual conditioning. Contextual conditioning may lower the threshold for sexual behavior with the result that a stimulus as impoverished as an immobile model containing only the head and neck of a female quail becomes sufficient to elicit normal levels of copulatory behavior. The results are also discussed as an example of conditioned stimulus facilitation of responding to an unconditioned stimulus.

Animals↗
PubMed1988

Analysis of open-label trials in torsion dystonia using high dosages of anticholinergics and other drugs.

We reviewed the records of 358 patients with various forms of focal, segmental, and generalized dystonia who had received pharmacotherapy in a systematic order, beginning with anticholinergics. If no benefit was encountered, we then tested clonazepam, baclofen, and other agents sequentially. In each situation the dosage was gradually increased until benefit or troublesome adverse effects were encountered. In this manner we obtained data on the percentage of patients who showed moderate to marked benefit. Anticholinergics were the most beneficial agent, confirming previous reports. Statistical analysis of this response revealed that benefit from anticholinergics was most likely if treatment was begun within 5 years after the onset of dystonia. From this analysis, it appears that delaying treatment beyond 5 years is likely to result in an unsatisfactory response.

Adolescent↗
PubMed1988

Conditioning of appetitive and consummatory sexual behavior in male Japanese quail.

Two different types of stimulus objects, a live female quail artificially adorned with bright orange feathers and an inanimate toy dog, served as conditioned stimuli. For subjects in experimental groups, the conditioned stimuli were presented shortly before access to a sexually receptive normal female quail. For subjects in control groups, exposure to the conditioned stimuli was unpaired with copulatory opportunity. Subjects in the experimental but not in the control groups quickly came to approach the location of the conditioned stimulus objects. When an adorned female quail served as the conditioned stimulus, the conditioned approach behavior was controlled by a combination of the presence of the orange adornments and the visual cues of the head and neck of the female bird, and the approach behavior persisted as the adorned female moved to new locations. When the toy dog served as the conditioned stimulus, the conditioned approach behavior was limited to the spatial cues that surrounded the toy dog during conditioning trials. Although both types of stimulus objects evoked conditioned approach behavior, only the adorned female stimulus supported copulatory behavior. This last finding indicates that copulatory behavior can become redirected toward novel stimuli as a result of conditioning, but only under special circumstances. The results are consistent with the suggestion that appetitive components of reproductive behavior are more susceptible to conditioning than consummatory components. Possible reasons for this are discussed, together with implications of the results for the contribution of conditioning processes to sexual selection.

Animals↗
PubMed1986

Structure of the DNA-Eco RI endonuclease recognition complex at 3 A resolution.

The crystal structure of the complex between Eco RI endonuclease and the cognate oligonucleotide TCGCGAATTCGCG provides a detailed example of the structural basis of sequence-specific DNA-protein interactions. The structure was determined, to 3 A resolution, by the ISIR (iterative single isomorphous replacement) method with a platinum isomorphous derivative. The complex has twofold symmetry. Each subunit of the endonuclease is organized into an alpha/beta domain consisting a five-stranded beta sheet, alpha helices, and an extension, called the "arm," which wraps around the DNA. The large beta sheet consists of antiparallel and parallel motifs that form the foundations for the loops and alpha helices responsible for DNA strand scission and sequence-specific recognition, respectively. The DNA cleavage site is located in a cleft that binds the DNA backbone in the vicinity of the scissile bond. Sequence specificity is mediated by 12 hydrogen bonds originating from alpha helical recognition modules. Arg200 forms two hydrogen bonds with guanine while Glu144 and Arg145 form four hydrogen bonds to adjacent adenine residues. These interactions discriminate the Eco RI hexanucleotide GAATTC from all other hexanucleotides because any base substitution would require rupture of at least one of these hydrogen bonds.

Amino Acids↗
PubMed1986

Preparing children for medical examinations: the importance of previous medical experience.

The relationship between past medical experience and children's response to preparation for medical examinations was investigated in 79 pediatric outpatients aged 3 to 12 years. Children were randomly assigned to one of five preparation conditions prior to receiving a medical examination and a throat culture: sensory information about the exam, training in coping skills (deep breathing and positive self-talk), combined sensory information and coping skills training, attention control, and no-treatment control. The results indicated that children with previous negative medical experiences demonstrated more behavioral distress during a throat culture examination that did children with previous positive or neutral medical experiences. In addition, the attention control condition appeared to increase the distress of children with previous negative medical experiences. Amount of past exposure to the specific medical procedure was not related to observed distress. The implications of these findings for the preparation of children for medical procedures are discussed.

Affective Symptoms↗
PubMed1985

Comparison of media with and without 'Panmede' for the isolation of Streptobacillus moniliformis from blood cultures and observations on the inhibitory effect of sodium polyanethol sulphonate.

Fastidious anaerobe broth and brain-heart infusion cysteine broth supplemented with 'Panmede' (a papain digest of ox liver) 2.5% supported the recovery of five Streptobacillus moniliformis strains from simulated blood cultures. Other media tested in parallel--brain heart infusion cysteine broth without 'Panmede' and Brewer's thioglycollate broth--were unreliable. Sodium polyanethol sulphonate (Liquoid) 0.05%, inhibited five isolates of S. moniliformis, including isolates from patients with Haverhill Fever. Occasionally, Liquoid 0.025% was also inhibitory and a heavy inoculum of one strain, NCTC11194, was completely inhibited by Liquoid 0.012% in simulated nutrient-broth blood cultures. These results suggest that the choice of media included in each blood-culture set is critical for the optimal isolation of S. moniliformis. Brain-heart infusion cysteine broth supplemented with 'Panmede', or commercially available fastidious anaerobe broth, without Liquoid, is recommended.

Anaerobiosis↗
PubMed1984

Two-fold symmetry of crystalline DNA-EcoRI endonuclease recognition complexes.

Recognition complexes between EcoRI endonuclease and either of two synthetic oligonucleotides (sequences CGCGAATTCGCG and TCGCGAATTCGCG) crystallize in Space Group P321 with unit cell parameters a = 128 and c = 47 A and a = 118.4 and c = 49.7 A, respectively. Native diffraction data to 3 A resolution have been collected from the form containing the tridecameric sequence. Electrophoretic analyses of dissolved crystals demonstrate that this form contains DNA and protein in a ratio of one double helix per enzyme dimer. The most likely asymmetric unit contents are one 31,000 dalton enzyme subunit and one strand of DNA, yielding VM values of 3.1 A3/dal and 2.8 A3/dal for the forms containing dodecameric and tridecameric DNA, respectively. This implies that the DNA-protein complex possesses two-fold rotational symmetry, which has been incorporated in the crystalline lattice.

Base Sequence↗
PubMed1982

Eco RI* specificity and hydrogen bonding.

Under standard conditions, Eco RI endonuclease uniquely recognizes the inverted repeat GAATTC. However, this specificity breaks down under non-standard conditions into what has been termed Eco RI* specificity, wherein many other sequences are recognized. We show here that the hydrolysis rates at all known Eco RI* sites can be summarized by the hierarchies: G much greater than A greater than T much greater than C at the first position, A much greater than [G,C] much greater than T at the second and third position, and the corresponding complements at the last three positions. This is consistent with a recognition model which assumes that there are two specific hydrogen bonds per base pair under standard conditions. One or more of these are randomly replaced by water under Eco RI* conditions and the position of a sequence within the appropriate hierarchy is primarily determined by the number of retained hydrogen bonds. These retained hydrogen bonds are common recognition features that can be identified by examining the DNA. The recognition points thereby identified for Eco RI all fall within the major groove of the DNA.

Base Sequence↗
PubMed1975

Specificity of substrate recognition by the EcoRI restriction endonuclease.

The substrate specificity of the EcoRI restriction endonuclease can be varied in vitro by changing the pH and the ionic environment of the reaction. Phosphodiester bond cleavage occurs at a DNA hexanucleotide sequence d(N-G-A-A-T-T-C-N)/d(N-C-T-T-A-A-G-N) when the ionic strength is high, 100 mM Tris-HCl, 50 mM NaCl, 5 mM MgCl2, and the pH is approximately 7.3. Lowering the ionic strength to 25 mM Tris-HCl, 2 mM MgCl2, and adjusting the pH to 8.5 reduces the recognition specificity of the EcoRI endonuclease to the tetranucleotide sequence, d(N-A-A-T-T-N)/d(N-T-T-A-A-N). The enzymatic activity responsible for this substrate recognition is referred to as EcoRI. Cleavage of pVH51 plasmid DNA under EcoRI conditions results in a number of partial digest fragments, some of which disappear slowly over a prolonged digestion period. This suggests that different recognition sites are cleaved at different rates. Comparison of DNA fragment patterns of modified and unmodified pVH51 DNA indicates that the canonical EcoRI sequence is the most rapidly cleaved site under EcoRI conditions. DNA modified in vivo by the EcoRI methylase is not cleaved by the EcoRI endonuclease under standard conditions, but is cleaved under EcoRI conditions at sites other than the standard EcoRI substrate.

Base Sequence↗