Search PubMed⌕ Search

Biomedical subjects

S M Green

Publications and source records attributed to S M Green.

At least 91 records · Page 5Linked to original sources
PubMed1995

One-step evolution of a dimer from a monomeric protein.

Deletion of six amino acids in a surface loop transforms staphylococcal nuclease from a monomeric protein into a very stable dimer (Kd < 1 x 10(-8)M). A 2 A X-ray crystal structure of the dimer (R = 0.176) shows that the carboxy-terminal alpha-helix has been stripped from its normal position in one monomer and is now incorporated into the equivalent position on the adjoining monomer. This swapping creates an association interface of 2900 A 2. A second, smaller interface of 460 A 2 is also formed. The spontaneous exchange or swapping of secondary structural elements provides a simple pathway for the formation of large, stable protein/protein interfaces and may play an important role in the evolution of oligomeric proteins.

Amino Acid Sequence↗
PubMed1995

Boutonniere deformity.

The boutonniere (French for button hole) deformity is a result of an injury to the finger extensor mechanism that causes a characteristic flexion attitude of the proximal interphalangeal joint and distal interphalangeal joint hyperextension. This article reviews the pertinent anatomy, the mechanisms of injury, the diagnosis, and a systematic approach to the prevention and treatment of the boutonniere deformity.

Acute Disease↗
PubMed1995

Which boys will fare worse? Early predictors of the onset of conduct disorder in a six-year longitudinal study.

OBJECTIVE: This article addresses the following questions: What are the best demographic and psychiatric predictors of the onset of conduct disorder (CD)? Does physical fighting play a role in the transition from oppositional defiant disorder (ODD) to CD? And what are the predictors of an earlier compared with a later onset of CD? METHOD: Data are presented on the follow-up of a clinic-referred sample of 177 preadolescent boys who were studied for a period of 6 years. Psychiatric assessments were based on information from the boys, their parent, and their teacher. RESULTS: Of all CD symptoms, physical fighting best predicted the onset of CD in bivariate analyses. Logistic regression showed that low socioeconomic status of the parent, ODD, and parental substance abuse best predicted the onset of CD. In addition, attention-deficit hyperactivity disorder (ADHD) predicted an early onset of CD. CONCLUSIONS: Parental substance abuse, low socioeconomic status, and oppositional behavior are key factors in boys' progression to CD. Physical fighting, although not a symptom of ODD, should be targeted in preventive interventions along with ODD symptoms. ADHD is implicated in the early onset of CD, but not in later-onset CD.

Adolescent↗
PubMed1994

A molecular rheostat. Co-operative rev binding to stem I of the rev-response element modulates human immunodeficiency virus type-1 late gene expression.

The complete biologically active human immunodeficiency virus type-1 (HIV-1) rev-response element (RRE) RNA is 351 nucleotides (nt) in length, and includes an extra 58 nt on the 5' end and 59 nt on the 3' end beyond the sites proposed in the original models for the RRE secondary structure. The extra sequences are able to form a duplex structure which extends Stem I. The presence of an elongated Stem I structure in the RRE RNA was confirmed by nuclease mapping experiments. Nuclease protection experiments have shown that rev binds to restricted regions of the RRE, including the high affinity site located at the base of Stem IIb and along the length of the Stem I region. The three large stem-loop structures which protrude from Stem I and Stem IIb (Stems IIc, III+IV and V) remain accessible to nucleases even in the presence of a large excess of protein. Gel-retardation experiments show that the truncations of Stem I reduced the total number of rev molecules that can bind co-operatively and with high affinity to the RRE RNA. To test whether the elongated Stem I structure is required for maximal rev activity, a series of truncations which progressively reduced the length of Stem I was introduced into an HIV-1 derived reporter plasmid. In the presence of rev and a functional RRE, there is an increase in the levels of gag and env mRNA in the cytoplasm and a decrease in levels of tat and rev mRNAs. Each of the truncations in Stem I reduced the rev responses, with the longest truncations producing the greatest losses of activity. The data suggest that the RRE acts as a "molecular rheostat" designed to detect rev levels during the early stages of the HIV growth cycle.

Base Sequence↗
PubMed1994

EyeChem 1.0: a modular chemistry toolkit for collaborative molecular visualization.

EyeChem is a network-aware and modular molecular visualization toolkit used within the Iris Explorer Visualization program. Use of the toolkit is illustrated via four typical EyeChem applications, which consist of Explorer maps constructed from chemically oriented modules and developed for use over the new generation of fast networks such as the UK SuperJanet system. EyeChem can also be used to prepare multimedia style visualizations in Quicktime or MPEG format of molecular properties and wavefunctions for archiving via the gopher+ wide area information system. The use of such information in electronic publishing of chemical information is discussed.

Chemistry↗
PubMed1994

Comparison of a suture technique with the modified Kessler method: resistance to gap formation.

We performed an in vitro study using canine flexor tendons to compare the tensile properties of a suture technique for flexor tendon repair with the standard modified Kessler technique. The technique employs a central wire loop that connects the two transverse limbs of the modified Kessler suture. Both techniques were studied with and without a Lembert epitendinous stitch. The technique combined with an epitendinous suture provided the strongest resistance to gap formation, and its load at gap initiation was 100% greater than the load in tendons repaired with the modified Kessler and an epitendinous suture. Because of its increased resistance to gap formation, this suture technique may provide a safer margin for controlled early active motion after flexor tendon repair.

Animals↗
PubMed1994

Delayed appendicitis from an ingested foreign body.

An unusual case of acute appendicitis induced by a metal drill bit that was ingested by a 27-year-old man 3 years before presentation is reported. This foreign body lodged in the patient's appendix and developed a fecalith coating. When this fecalith coating enlarged enough to obstruct the appendiceal lumen, the patient presented with classic acute appendicitis. Foreign body-induced appendicitis is reviewed.

Acute Disease↗
PubMed1994

Validation of diphenhydramine as a dermal local anesthetic.

STUDY OBJECTIVE: Although diphenhydramine has been recommended as an alternate local anesthetic for patients claiming allergy to lidocaine, no prior placebo-controlled evaluations of diphenhydramine for dermal anesthesia have been performed. We sought to determine the relative efficacy of diphenhydramine compared to saline placebo and lidocaine. DESIGN: Prospective, randomized, double-blind, placebo-controlled clinical trial. SETTING AND PARTICIPANTS: Twenty-four healthy adult volunteers. INTERVENTIONS: Subjects received intradermal 0.5-mL injections of diphenhydramine 1%, diphenhydramine 2%, lidocaine 1%, and normal saline placebo in a randomized, double-blind fashion. Extent of anesthesia (in mm2) was assessed at one, two, five, ten, 20, and 30 minutes. Pain of initial infiltration was assessed with a visual analog scale. MEASUREMENTS AND MAIN RESULTS: Diphenhydramine 1% produced greater anesthesia than placebo (P < .001) and equivalent anesthesia to lidocaine 1% (P = .889). (Our sample size had 90% power to detect a difference of 30% from the peak anesthesia observed.) Diphenhydramine 2% was less effective than diphenhydramine 1%; however, this difference was not statistically significant (P = .295). Infiltration of either concentration of diphenhydramine was significantly more painful than either lidocaine or saline (P < or = .001) for all comparisons). No clinically important complications were noted. CONCLUSION: In this study of 24 adult volunteers, diphenhydramine 1% was as effective as lidocaine 1% for achieving dermal local anesthesia, although injection was more painful. Although no clinically important complications were noted in our study, the safety of diphenhydramine remains to be established, especially in areas with poor collateral perfusion (eg, digits, pinna, and nose).

Adult↗
PubMed1994

Human enteric Caliciviridae: a new prevalent small round-structured virus group defined by RNA-dependent RNA polymerase and capsid diversity.

Sequence comparison of the RNA-dependent RNA polymerases of small round-structured viruses (SRSVs) from 10 recent U.K. outbreaks of gastroenteritis revealed significant genetic variation. Computer analyses indicated that these viruses can be divided into two discrete groups. SRSV group I contains the previously characterized antigenic type 1 Norwalk and type 3 Southampton viruses. The amino acid sequences of the RNA polymerase, capsid and ORF3 of these two viruses are relatively similar (about 92%, 69% and 72% amino acid identity, respectively). A representative member of group II SRSVs, Bristol virus, was subjected to a detailed genetic analysis. Bristol virus is a recent antigenic type 2 isolate from a U.K. hospital outbreak of gastroenteritis. Using a single clinical sample the 3'-terminal 3881 nucleotide cDNA sequence [excluding the poly(A) tail] of this virus was determined. Analysis of the sequence revealed significant differences from those of group I viruses with the RNA polymerase region, capsid and ORF3 showing only about 62%, 43% and 30% amino acid identity respectively with the equivalent proteins of the Norwalk and Southampton viruses. These data suggest that the morphologically identical SRSVs belong to at least two genetically distinct groups.

Amino Acid Sequence↗
PubMed1994

Effect of fat- and sucrose-containing foods on the size of eating episodes and energy intake in lean males: potential for causing overconsumption.

OBJECTIVE: This study compared the action of sucrose- and fat-containing foods on the size of eating episodes (satiation) and postingestive energy intake (satiety). DESIGN: The study was a 2 x 2 within-subjects design, each subject received each of four conditions in a counterbalanced order. SETTING: The study was carried out in the Human Appetite and Nutrition Research Unit. SUBJECTS: Eighteen normal-weight young male University students. INTERVENTIONS: Subjects consumed a low (2238 kJ) or high (3962 kJ) energy lunch followed 2 h later by the opportunity to eat freely from an ad libitum selection of high fat, low sucrose or high sucrose, low fat snacks. Visual analogue rating scales to record subjective feelings of hunger, fullness and related sensations were completed periodically through the test day. RESULTS: When offered a high sucrose, low fat selection of snacks subjects consumed less energy than when offered a high fat, low sucrose selection (P < 0.0001). However postingestive satiety was similar. The energy intake of snacks consumed was also determined by hunger; the low energy lunch gave rise to a higher level of hunger and greater intake (P < 0.01). Energy intake for the total day was significantly more when high fat, low sucrose snacks were consumed (P < 0.001). CONCLUSIONS: These results have indicated that the size of an eating episode is influenced by the level of hunger and the nutrient composition of the foods consumed. High fat foods (probably due to higher energy density) lead to a passive overconsumption which generates a relatively weak satiety.

Adult↗
PubMed1993

Patterns of nonadditivity between pairs of stability mutations in staphylococcal nuclease.

To identify interactions between amino acid positions in staphylococcal nuclease that affect its stability, a collection of 71 double-mutant forms was constructed from 22 previously characterized single mutants. These single mutations were assigned to three different classes on the basis of their m value [m = d(delta G)/d[GuHCl]], a parameter that has been correlated with energetically significant changes in the structure of the denatured state [Green et al. (1992) Biochemistry 31,5717-5728]. Several mutant pairs from five of the six possible double-mutant classes were analyzed by guanidine hydrochloride denaturation to determine the extent to which changes in stability (delta delta GH2O) and changes in the m value (delta mGuHCl) reflect the sum of the effects of the individual mutants. The differences between the values for delta delta GH2O and delta mGuHCl estimated on the assumption of additivity and those obtained by experiment, i.e., delta delta delta G and delta delta m, were calculated for each double-mutant protein. Surprisingly, a large majority of double mutants from four of the five classes exhibited positive values of delta delta delta G and delta delta m; i.e., they were more stable and displayed a higher sensitivity to GuHCl than predicted on the basis of additivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

High affinity binding of TAR RNA by the human immunodeficiency virus type-1 tat protein requires base-pairs in the RNA stem and amino acid residues flanking the basic region.

The binding site for tat protein on TAR RNA has been defined in quantitative terms using an extensive series of mutations. The relative dissociation constants for the mutant TAR RNAs were measured using a dual-label competition filter binding assay in which 35S-labelled wild-type TAR RNA (K1) was competed against 3H-labelled mutant TAR RNA (K2). The error in the self-competition experiment was usually less than 10% (e.g. K2/K1 = 1.07 +/- 0.05, n = 19) and the experimental data accurately matched theoretical curves calculated with fitted dissociation constants. Mutations in U23, a critical residue in the U-rich "bulge" sequence, or in either of the two base-pairs immediately above the "bulge", G26.C39 and A27.U38 reduced that affinity by 8- to 20-fold. Significant contributions to tat binding affinity were also made by the base-pairs located immediately below the bulge. For example, mutation of A22.U40 to U.A reduced tat affinity 5-fold, and mutation of G21.C41 to C.G reduced tat affinity 4-fold. The binding of a series of peptides spanning the basic "arginine-rich" sequence of tat was examined using both filter-binding and gel mobility shift assays. Each of the peptides showed significantly reduced affinities for wild-type TAR RNA compared to the tat protein. The ADP-2 (residues 43 to 72), ADP-3 (residues 48 to 72) and ADP-5 (residues 49 to 86) peptides were unable to discriminate between wild-type TAR RNA and TAR RNA mutants with the same fidelity as the tat protein. For example, these peptides showed no more than 3-fold reductions in affinity relative to wild-type TAR RNA for the U23-->C mutation in the bulge, or G26.G39-->C.G mutation in the stem of TAR RNA. By contrast, the ADP-I (residues 37 to 72), ADP-4 (residues 32 to 62) and ADP-6 (residues 32 to 72) peptides, which each carry amino acid residues from the "core" region of the tat protein have binding specificities that more closely resemble the protein. The ADP-4 and ADP-6 peptides showed between 4- and 7-fold reductions in affinity for the U23-->C or G26.C39-->C.G mutations. The ADP-1 peptide most closely resembles the protein in its binding specificity and showed 9-fold and 14-fold reductions in affinity for the two mutants, respectively. Chemical-modification interference assays using diethylpyrocarbonate (DEPC) and ethylnitrosourea (ENU) were also used to compare the binding properties of the tat protein and the tat-derived peptides.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1993

Evidence for developmentally based diagnoses of oppositional defiant disorder and conduct disorder.

This paper compares the validity of DSM-III-R diagnoses of oppositional defiant disorder (ODD) and conduct disorder (CD) and an alternative option which is subdivided into three levels according to developmental sequence and severity: modified oppositional disorder (MODD), intermediate CD (ICD), and advanced CD (ACD). Using a sample of 177 boys followed over 3 years, both the DSM-III-R and the alternative diagnostic constructs are evaluated on three criteria: symptom discriminative validity, and diagnostic external and predictive validity. Most DSM-III-R ODD and CD symptoms discriminated between ODD and CD, but exceptions are noted. Additional analyses demonstrated considerable overlap among DSM-III-R oppositional symptoms. The majority of the symptoms proposed for the alternative option could be assigned to a specific level based on acceptable symptom discrimination. External validity lent support to the distinctions between DSM-III-R ODD and CD, and between MODD, ICD, and ACD. MODD was a better predictor than ODD of which MODD, ICD, and ACD. MODD was a better predictor than ODD of which boys received a later diagnosis of CD. Suggestions are made for the inclusion and exclusion of symptoms for developmentally based diagnoses of oppositional and conduct disorders.

Antisocial Personality Disorder↗
PubMed1993

Atropine for the treatment of biliary tract pain: a double-blind, placebo-controlled trial.

STUDY OBJECTIVE: To compare the efficacy of IM atropine with placebo for the treatment of pain caused by biliary tract disease. DESIGN: Prospective randomized, double-blind, crossover study. SETTING: Emergency departments of a university medical center and affiliated county hospital. PARTICIPANTS: Fifty-five adults with biliary tract disease. INTERVENTIONS: Subjects were randomized to receive either 0.6 mg (0.5 mL) IM atropine or normal saline placebo in a double-blinded manner. If pain relief with the initial injection was inadequate, patients received the alternate injection. Pain was assessed by visual analog scale (0 to 100 mm) before the initial injection and 30 to 40 minutes after each subsequent injection. MEASUREMENTS AND MAIN RESULTS: Relief of pain was complete after the initial injection in four of 28 (14%) who received atropine and four of 27 (15%) who received normal saline (P = .956). For subjects who received both injections, atropine and placebo resulted in similar pain relief (-12.0 mm versus -16.0 mm; P = .316). There also was no difference in pain relief between atropine and placebo for the subset of patients with biliary colic receiving both injections (-15.2 mm versus -17.0 mm; P = .658). This study had more than 80% power to detect a 7.5-mm difference in pain relief between atropine and placebo in all patients with biliary tract disease and a 12.5-mm difference in those with biliary colic. CONCLUSION: Atropine is no better than placebo in the treatment of biliary tract pain.

Adult↗
PubMed1993

Successful resuscitation from cardiac arrest using sublingual injection for medication delivery.

A 7-month-old child suffered a cardiopulmonary arrest. After eight minutes of basic CPR by the parents, paramedics arrived and found the child in asystole. Endotracheal intubation and peripheral venous access were unsuccessful, and intraosseous equipment was unavailable in the field. The patient then received 1.5 mg epinephrine and 0.15 mg atropine injected sublingually with prompt return of a sinus rhythm and a palpable pulse. One hour after arrival in the emergency department, the patient again arrested, this time fatally. This case may represent the first report of successful resuscitation from cardiac arrest using sublingually injected medications.

Administration, Sublingual↗
PubMed1993

Tympanometric evaluation of middle ear barotrauma during recreational scuba diving.

We report the first prospective evaluation of middle ear barotrauma in experienced recreational scuba divers. In this pilot study, tympanometric and otoscopic evaluations were performed daily on two experienced scuba divers engaged in multi-day repetitive diving. Middle ear pressures decreased in proportion to diving frequency, demonstrating eustachian tube dysfunction which promptly reversed upon cessation of diving Otoscopic evidence of traumatic injury to the middle ear occurred in proportion to diving frequency, and also readily reversed upon cessation of diving. Tympanic membrane compliance remained normal, often despite pronounced otoscopic abnormalities. Otologic symptoms and impairment of acuity were not observed. Tympanometry appears to be a valuable modality for the verification of middle ear hemorrhage or tympanic membrane rupture. This preliminary data should assist investigators in planning more comprehensive studies of middle ear barotrauma, including clinical trials of treatment and prophylactic interventions for this common condition.

Acoustic Impedance Tests↗
PubMed1993

Groundwater pesticides: interactive effects of low concentrations of carbamates aldicarb and methomyl and the triazine metribuzin on thyroxine and somatotropin levels in white rats.

Using full-factorial design experiments for three variables at two levels each and center replicates, we examined the effects of common agricultural carbamate insecticides, aldicarb and methomyl, and a triazine herbicide, metribuzin, on hormone levels in Sprague-Dawley rats. Fifty-four female rats were sampled at 2 and 6 wk during a 6-wk exposure to individual chemicals or to combinations of them. Some main effects and interaction effects were significant. For example, rats treated with the herbicide (metribuzin) were hyperthyroid. The interactions of all three chemicals also significantly increased thyroxine levels. One year later, we repeated these experiments for 16 wk using 54 male rats; the results were very similar. Metribuzin alone significantly increased thyroxine throughout the second study (at 7, 13, and 16 wk). Somatotropin levels were significantly altered after 13 wk of exposure. The same concentrations and mixtures of these three pesticides have now been shown to be implicated in learning impairment and other neurological functions, immune parameter changes, and endocrine changes. These findings support the concept of the interconnectedness of the nervous, endocrine, and immune systems and raise the likelihood of impacts on all three systems if one is shown to be affected. Development, growth, and reproduction all depend on the proper function of these three systems. These results strongly suggest the need to reassess currently allowed "safe" levels of chemicals based on adult dosages that are accepted in ground-water and in our food supplies.

Aldicarb↗