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Biomedical subjects

M Lewis

Publications and source records attributed to M Lewis.

At least 433 records · Page 24Linked to original sources
PubMed1984

99mTc-pyrophosphate imaging in patients with acute myocardial infarction: comparison of planar imaging with single-photon tomography with and without blood pool overlay.

To test the hypothesis that single-photon emission computed tomography (SPECT) of 99mTc-pyrophosphate (99mTc-PPi) with and without the overlay of tomographic blood pool scintigrams might detect small infarcts not identified by planar imaging, 52 patients were studied 3.2 +/- 2.0(SD) days after hospital admission for suspected acute myocardial infarction. Patients were chosen prospectively for tomographic study primarily, but not exclusively, because planar four-view imaging with 99mTc-PPi was either negative or equivocal. SPECT was performed with a commercial rotating detector system immediately after planar imaging on one occasion. Corresponding 99mTc-PPi and blood pool sections were mapped into opposite halves of a bichromic color table and displayed as an overlay. Planar images, SPECT and SPECT with blood pool overlay were interpreted separately and in random order without knowledge of clinical data. Seventeen patients had transmural infarcts (four anterior, 13 inferior), 19 had nontransmural infarcts, and 16 patients did not have acute myocardial infarction. The sensitivity of SPECT with blood pool overlay was significantly better than planar imaging for the entire group with myocardial infarction (97% vs 78%; p less than .025); this was primarily due to increased sensitivity in the detection of nontransmural myocardial infarction (95% vs 67%; p less than .05), although in one additional patient inferior transmural myocardial infarction was also detected by the SPECT overlay technique. The specificities of the SPECT overlay technique and planar imaging were not significantly different; however, receiver operating characteristic analysis showed enhanced observer confidence with the tomographic method. SPECT without overlay was intermediate in sensitivity and specificity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Conduct disorder and its synonyms: diagnoses of dubious validity and usefulness.

Psychiatrically hospitalized adolescents from city and voluntary services who had been diagnosed as having conduct disorder were compared with psychiatrically hospitalized adolescents who had never been so diagnosed. There were no significant symptomatic differences. The major factor distinguishing adolescents ever diagnosed as having conduct disorder was violence, regardless of other symptoms. The most common discharge diagnosis of those who had formerly been diagnosed as having conduct disorder was schizophrenia. However, even violence did not distinguish those discharged with a diagnosis of conduct disorder from those whose diagnoses were subsequently changed. With its focus on manifest behaviors and its lack of clear exclusionary criteria, the conduct disorder diagnosis obfuscates other potentially treatable neuropsychiatric disorders.

Adolescent↗
PubMed1984

Acquisition of conversational response skills by young Down syndrome and nonretarded young children.

The acquisition of conversational response skills by young retarded and nonretarded children matched for chronological age (CA) and expressive linguistic ability was compared. Retarded children showed delayed response performance in comparison with CA-matched nonretarded peers. When matched for language level, however, retarded children demonstrated significantly greater response abilities than did nonretarded children. These findings indicate that the language development process of retarded children is developmentally delayed and different with respect to the synchrony of syntactic development and communicative competence. The findings further suggest that the acquisition of conversational response rules is not determined by the child's expressive language ability as measured by a mean length of utterance score, but is directly influenced by social-experiential factors as measured by the child's age.

Child, Preschool↗
PubMed1984

Early mother-infant interaction and infant cognitive status as predictors of school performance and cognitive behavior in six-year-olds.

This study examines the predictive validity of early mother-infant interaction for development in early childhood. Observations of the interaction between 40 mothers and their 3-month-old infants were used in multiple regression analyses to predict math and reading achievement, conversation, and WISC Vocabulary and Block Design performance at 6 years of age. Frequency and proportion of interaction measures were derived that represent types of maternal stimulation and responsivity. Frequency measures are counts of the occurrence of a given behavior, while proportion measures are the proportion of the mother's total behavior that occurred as a specific behavior. Percentage responsivity measures are the best predictors of child performance. However, type of responsivity is differentially related to cognitive performance. Proximal and vocal responsivity are related to reading and conservation, while distal responsivity to infant distress is related to math achievement. Results suggest that maternal behavior can be characterized along several different and conceptually relevant dimensions as these dimensions differentially account for aspects of early development.

Achievement↗
PubMed1984

Time-series analysis of stereotyped movements: relationship of body-rocking to cardiac activity.

The pathological stereotypies frequently observed among severely mentally retarded and autistic persons are highly rhythmical in nature. Most attempts to quantify such behavior, however, have not analyzed stereotypy in terms of its cyclical properties. In the present paper we have detailed a method for electronically transducing stereotyped body-rocking and analyzing its frequency and amplitude characteristics with a standard polygraph and microprocessor. The relationship between stereotyped body-rocking and cardiac activity was also described using time-series analysis. The method described should provide a sensitive index of various experimental manipulations and treatment effects.

Adult↗
PubMed1984

Predicting psychopathology in six-year-olds from early social relations.

113 children were seen at 1 and 6 years of age in order to examine the relationship between the quality of the early attachment relationship and later psychopathology. On the basis of scores from the Achenbach and Edelbrock Child Behavior Profile, an outcome measure of psychopathology at 6 years, the results indicated different outcomes for male and female children. For males, attachment classification at 1 year was significantly related to later psychopathology; insecurely attached males showed more psychopathology than securely attached males. No relationship between attachment and later psychopathology was observed for females. Even for males, the attachment classification only partly predicted later behavioral problems. Several other factors, including life-stress events and family demographic variables, appeared to influence the development of psychopathology. The findings suggest that although the child's attachment relationship plays an important role in the development of psychopathology, the child is neither made invulnerable by an early secure attachment nor doomed to psychopathology by an insecure attachment.

Child↗
PubMed1983

Cervical Chlamydia trachomatis and mycoplasmal infections in pregnancy. Epidemiology and outcomes.

In a prospective study of chlamydial and mycoplasmal infections in pregnancy, Chlamydia trachomatis occurred in 8.0%, Mycoplasma hominis in 23.5%, and Ureaplasma urealyticum in 72.3% of 1,365 enrollees. By multivariate analysis, C trachomatis was correlated with lower socioeconomic status, age 23 years or younger, and 12 years or less of schooling. Ureaplasma urealyticum was correlated with age 23 years or younger and lower socioeconomic status. Mycoplasma hominis was correlated with more than one recent sexual partner, first intercourse at age 17 years or younger, and higher socioeconomic status. These cervical infections did not predict low birth weight, abortion, stillbirth, prematurity, or premature rupture of membranes. Only M hominis predicted endometritis/fever after vaginal delivery (relative risk, 7.3). IgM-seropositive C trachomatis-infected women had more low-birth-weight infants and more premature rupture of membranes than either IgM-negative C trachomatis-infected women or C trachomatis culture-negative women. Thus, only certain subgroups of infected women may experience adverse pregnancy outcomes.

Adult↗
PubMed1983

Comparison of the structures of cro and lambda repressor proteins from bacteriophage lambda.

The three-dimensional structures of cro repressor protein and of the amino-terminal domain of lambda repressor protein, both from bacteriophage lambda, are compared. The second and third alpha-helices, alpha 2 and alpha 3, are shown to have essentially identical conformations in the two proteins, confirming the significance of the amino acid sequence homology previously noted between these and other DNA binding proteins in the region corresponding to these helices. The correspondence between the two-helical units in cro and lambda repressor protein is better than the striking agreement noted previously between two-helical units in cro and catabolite gene-activator protein. Parts of the first alpha-helices of repressor and cro show a structural correspondence that suggests a revised sequence homology between the two proteins in their extreme amino-terminal regions. In particular, there is a short loop between the alpha 1 and alpha 2 helices of lambda repressor that is missing from cro. This structural difference may account for the observed differences found with different cros and repressors in the pattern of phosphates whose ethylation prevents the binding of these proteins to their specific recognition sites. Although the two proteins have strikingly similar alpha 2-alpha 3 helical units that are presumed to bind to DNA in an essentially similar manner, stereochemical restrictions prevent the alpha 2-alpha 3 units of the respective proteins aligning on the DNA in exactly the same way.

Amino Acid Sequence↗
PubMed1983

Anxiogenic aspects of diazepam withdrawal can be detected in animals.

Animals can be trained to discriminate the presence of pentylenetetrazol, and this discrimination has previously been proposed as an animal bioassay for anxiogenicity. In rats made dependent on diazepam, pentylenetetrazol-like stimuli occurred during spontaneous or precipitated (with RO 15-1788) withdrawal; these stimuli were blocked by pentobarbital. These results demonstrate that the pentylenetetrazol-based animal model of anxiety can be used to objectively quantify a subjective aspect of benzodiazepine dependence/withdrawal.

Animals↗
PubMed1983

Refined crystal structure of carboxypeptidase A at 1.54 A resolution.

The crystal structure of bovine carboxypeptidase A (Cox) has been refined at 1.54 A resolution using the restrained least-squares algorithm of Hendrickson & Konnert (1981). The crystallographic R factor (formula; see text) for structure factors calculated from the final model is 0.190. Bond lengths and bond angles in the carboxypeptidase A model have root-mean-square deviations from ideal values of 0.025 A and 3.6 degrees, respectively. Four examples of a reverse turn like structure (the "Asx" turn) requiring an aspartic acid or asparagine residue are observed in this structure. The Asx turn has the same number of atoms as a reverse turn, but only one peptide bond, and the hydrogen bond that closes the turn is between the Asx side-chain CO group and a main-chain NH group. The distributions of CO-N and NH-O hydrogen bond angles in the alpha-helices and beta-sheet structures of carboxypeptidase A are centered about 156 degrees. A total of 192 water molecules per molecule of enzyme are included in the final model. Unlike the hydrogen bonding geometry observed in the secondary structure of the enzyme, the CO-O(wat) hydrogen bond angle is distributed about 131 degrees, indicating the role of the lone pair electrons of the carbonyl oxygen in the hydrogen bond interaction. Twenty four solvent molecules are observed buried within the protein. Several of these waters are organized into hydrogen-bonded chains containing up to five waters. The average temperature factor for atoms in carboxypeptidase A is 8 A2, and varies from 5 A2 in the center of the protein, to over 30 A2 at the surface.

Amino Acid Sequence↗
PubMed1983

Otolaryngologic complications of acute porphyria.

The porphyrias are a group of diseases which may be complicated by acute neurological crises having serious morbidity and a high rate of mortality. We report a case of acute porphyria in which an acute neurological crisis, resulting in loss of laryngeal function, precipitated life-threatening aspiration pneumonia.

Acute Disease↗
PubMed1983

Survival following massive overdose of adrenergic blocking agents (acebutolol and labetalol).

Massive overdosage of adrenergic blocking drugs is associated with severe morbidity and a high mortality rate. We report the case of a 24-year-old medical intern who ingested 9.6 g acebutolol, 7.2 g labetalol and 0.625 g trimipramine in an attempted suicide. Blood samples drawn on admission were shown to contain markedly elevated plasma levels of acebutolol and its major metabolite and of labetalol. The patient was deeply comatose on admission. The heart rate was 60 min-1 (sinus rhythm) and the blood pressure was clinically unrecordable. Atropine, isoproterenol and dopamine initially had no effect on either heart rate or blood pressure. Only following the administration of inordinately large doses of isoproterenol and dopamine, together with glucagon was a clinical response obtained. The patient remained haemodynamically dependent on dopamine for 12 h and isoproterenol for 65 h. The total dose of isoproterenol administered was 260 mg, two thirds of this during the first 12 h. The patient left hospital well after 7 days but was readmitted after 26 days because of intestinal obstruction due to ischemic bowel necrosis.

Acebutolol↗