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Biomedical subjects

S Peck

Publications and source records attributed to S Peck.

At least 19 recordsLinked to original sources
PubMed2005

Hyperventilation and amplified blood pressure response: is there a link?

Based on prior studies, the hypothesis that hyperventilation (HV) may have a pressor effect and play a causal role in hypertension has been suggested. The objective of this study was to correlate HV with blood pressure (BP)-change during a postural challenge. Consecutive subjects referred for evaluation of syncope, dizziness, chronic fatigue syndrome (CFS), fibromyalgia, or non-CFS fatigue were assessed with a 10-min supine 30-min head-up tilt test combined with capnography. We selected for analysis the records of patients aged 17-70 years, not taking vasoactive medications, having sitting systolic BP (SBP) < 140 mmHg, sitting diastolic BP (DBP) < 90 mmHg, and who completed 30 min of tilt. HV was diagnosed when end-tidal pressure of CO2 < 30 mmHg was recorded consecutively for > or = 10 min. Postural hypertension (PHT) was diagnosed when DBP on tilt > or = 90 mmHg was recorded consecutively for > or = 10 min. DBP-change was computed as (median DBP on tilt) -(median DBP supine). PHT and DBP-change were correlated with HV. A total of 320 patient charts were reviewed. PHT was present in 30 cases. The mean DBP-change in patients with PHT was +9.9 mmHg (s.d. 5.8), with three patients manifesting HV. Of the remaining 290 patients, 56 had HV, their mean DBP-change was -0.3 mmHg (s.d. 7.2). The other 234 patients without HV had a mean DBP-change +0.95 mmHg (s.d. 5.7), comparable to the DBP-change in patients with HV. In, conclusion, posturally induced HV was not associated with an increase in BP, nor was PHT associated with HV, except in a small minority of cases.

Adolescent↗
PubMed2000

Relation of temporal creatine kinase-MB release and outcome after thrombolytic therapy for acute myocardial infarction. TAMI Study Group.

Measuring biochemical marker release after acute myocardial infarction helps in estimating infarct size and prognosis. We sought to relate in-hospital outcomes and curve-fitted creatine kinase (CK)-MB variables after thrombolysis. We measured CK-MB mass initially and at 30 and 90 minutes, and at 3, 8, and 20 hours after thrombolysis in 130 patients also undergoing cardiac catheterization at 90 minutes and at 5 to 7 days. Data were fitted, and maximums and curve areas calculated. CK-MB maximums related to infarct location (p = 0.014) and time to therapy (p = 0.002); curve area did not. Neither maximums nor curve area related to Thrombolysis in Myocardial Infarction trial flow grade at 90 minutes. Maximums related to ejection fraction at 90 minutes (p = 0.0004) and at 5 to 7 days (p = 0.0014), as did curve area (p = 0.0076 and 0.030, respectively). Maximums related to infarct zone function at 90 minutes (p = 0.024) and at 5 to 7 days (p = 0.042); curve area related only at 90 minutes (p = 0.027). Both maximums and curve area predicted congestive heart failure (p = 0.008 and p = 0.042, respectively) and a composite of congestive heart failure or death (p = 0.004 and p = 0.047, respectively); however, after adjusting for maximums, curve area no longer predicted congestive heart failure (p = 0.92). Maximums predicted the composite outcome after adjustment for curve area, and showed a trend toward predicting congestive heart failure (p = 0.089). We conclude that CK-MB maximums relate to infarct zone function, left ventricular function, and in-hospital outcomes after thrombolysis for acute myocardial infarction.

Biomarkers↗
PubMed2000

Tooth-size reduction associated with occurrence of palatal displacement of canines.

This study investigates mesiodistal crown size of the maxillary and mandibular incisors of patients with palatally displaced canines (PDC). Pretreatment dental casts of orthodontic patients with PDC of 1 or both maxillary canines (N = 31; M10:F21) were collected. This PDC sample was matched according to age and sex with pretreatment dental casts from unaffected orthodontic patients. For the PDC and matched control samples, maximum mesiodistal crown diameters were recorded for the 4 incisors on the left side only. The results showed that, on average, the mesiodistal crown diameters for the maxillary and mandibular incisors measured smaller in the PDC sample than in the control sample. These findings of statistically significant tooth-size reductions associated with PDC occurrence indicate a generalized pattern of reduced tooth size as a characteristic associated with the PDC anomaly. Further, the presence of generalized tooth-size reduction in cases with palatally displaced canines helps explain why most orthodontic treatment plans for PDC patients are of the nonextraction type.

Adolescent↗
PubMed2000

Adequacy of maxillary dental arch width in patients with palatally displaced canines.

This study investigates maxillary dental arch width in subjects with palatally displaced canines. Pretreatment dental casts of orthodontic patients with one or both maxillary canines palatally displaced (n = 31; male, 10; female, 21) were collected. This sample was matched according to sex and age with pretreatment dental casts from unaffected orthodontic patients. Arch widths were recorded between the maxillary first premolars and between the maxillary first molars. Interpremolar arch width and intermolar arch width comparisons between the sample with palatally displaced canines and the reference sample showed no statistically significant differences in their means, thus indicating that there was no statistically significant difference in the anterior and posterior arch width between the affected subjects and the control subjects. Thus, affected patients exhibit adequacy of maxillary dental arch width. This evidence refutes earlier conclusions that deficiency in maxillary transverse arch width is an associated contributing factor in the genesis of the anomaly of palatally displaced canines. Clinically, adequacy of dental arch width helps explain the "nonextraction" diagnostic appearance of most of these patients when they present for treatment.

Adolescent↗
PubMed2000

Effects of escape to alone versus escape to enriched environments on adaptive and aberrant behavior.

Escape-maintained aberrant behavior may be influenced by two outcomes: (a) a break from the activity and (b) subsequent access to preferred activities. To assess this hypothesis, a treatment was developed that analyzed response allocation across two break options: break alone and break with access to preferred social activities. The break with preferred activities decreased aberrant behavior and increased appropriate behavior.

Adaptation, Psychological↗
PubMed2000

The effects of presession exposure to attention on the results of assessments of attention as a reinforcer.

The effects of presession exposure to attention on responding during subsequent assessments of attention as a reinforcer were evaluated across three behavioral assessments. In Experiment 1, a contingent attention assessment condition was preceded by either a noncontingent attention condition (free play) or a contingent escape condition. In Experiment 2, a diverted attention with extinction condition was preceded by either an alone or a free-play condition. In Experiment 3, a two-choice preference assessment was preceded by either 10 min of free play or 10 min of playing alone. In each experiment, the participant responded differentially within the test condition according to the presence or absence of dense schedules of attention immediately prior to that condition. The results of this study show that events occurring immediately prior to an assessment condition can influence behavior within the assessment.

Attention↗
PubMed1999

Occlusal changes from adolescence to adulthood in untreated patients with Class II Division 1 deepbite malocclusion.

A sample of 47 untreated children (M 32:F 15) with Class II Division 1 (II/1) deep-overbite malocclusion was collected from a group of patients who declined orthodontic therapy. Longitudinal records consisted of plaster dental casts and lateral cephalograms at original diagnosis and plaster dental casts at a follow-up observation in adulthood, an average of 11.5 years later. To study retrospectively natural changes in dental occlusion during this interval, plaster-cast millimetric measurements were recorded of sagittal dental relationships (first molar and canine), overjet, overbite, and crowding/spacing at the two registrations. Results showed statistically significant improvements in untreated II/1 deepbite malocclusion from adolescence to adulthood for all measured occlusal variables except development of mild crowding. Therefore, assumptions that untreated II/1 distoclusion will worsen with age appear to be unfounded. The evidence indicates that the absence of orthodontic correction for adolescent patients with Class II Division 1 deepbite malocclusion will not usually lead to measurable occlusal deterioration in young adulthood.

Adolescent↗
PubMed1998

On the phenomenon of intraosseous migration of nonerupting teeth.

Little is know about intraosseous migration of nonerupting teeth, a rare natural condition of horizontal tooth movement and impaction. It occurs only in the mandible and involves primarily the second premolar or the canine. When the second premolar is the affected tooth, it always is found distal to its normal position. The origins of the second premolar intraosseous migration phenomenon are obscure and usually no treatment is recommended. Intraosseous migration involving the canine is commonly called transmigration because the affected canine moves mesially across the mandibular symphysis to the opposite side of the mandible. Analysis of 50 published cases of canine transmigration indicated higher occurrence in women and no sidedness preference. In over 80% of the studied cases, the canine remained nonerupted and, of the 24 cases receiving some treatment, all but two underwent extraction of the anomalous canine. The canine transmigration phenomenon appears to show signs of having some genetic determinants.

Bicuspid↗
PubMed1998

Class II Division 2 malocclusion: a heritable pattern of small teeth in well-developed jaws.

Angle's designation of the Class II Division 2 (II/2) malocclusion recognizes a unique combination of overbite, incisor retroclination, and sagittal discrepancy. A very severe II/2 phenotype, characterized by concealment of the mandibular incisors in occlusion, has been called Deckbiss in German, or cover-bite. In this report, the cover-bite malocclusion is studied to identify morphological factors associated with Angle's II/2 occlusal discrepancy. Selected X-ray cephalometric and odontometric measurements were recorded for 23 subjects (M14; F9) with II/2 cover-bite malocclusion. Data were compared with those from a control-reference sample of 537 individuals. Cephalometrically, the II/2 cover-bite sample showed a pattern of strong vertical posterior development of the mandible with forward-rotation and skeletofacial hypodivergence (p < 0.0001). Anteroposteriorly, the maxillomandibular dentoalveolar relationship was relatively normal, and the basal bone region of the mandibular corpus appeared significantly well developed anteriorly, accounting for excessive bony chin projection (p < 0.0001). Dentally, mesiodistal tooth diameters for the maxillary and mandibular incisors of the II/2 cover-bite sample were significantly smaller than those of the reference sample (p < 0.002), pointing to systematically reduced tooth-size as a trait associated with II/2 malocclusion. These findings of a characteristic pattern of heritable skeletal and tooth-size features in II/2 cover-bite malocclusion indicate the presence of strong genetic influences in the formation of Angle's II/2 deep-bite discrepancy.

Adolescent↗
PubMed1998

Mandibular lateral incisor-canine transposition, concomitant dental anomalies, and genetic control.

Mandibular lateral incisor-canine (Mn.I2.C) transposition is a rare developmental disturbance of tooth order characterized by positional interchange of the two teeth. In children with Mn.I2.C anomaly, the mandibular lateral incisor shows distal ectopic eruption and the adjacent canine subsequently erupts mesial to it. A sample of 60 orthodontic patients with Mn.I2.C transposition was studied using roentgenograms taken at the time of diagnosis. Two age-related phenotypes of the anomaly were identified: early-stage (median age, 9 years) and mature-stage (median age, 12 years). Mn.I2.C transposition occurred bilaterally in 10 subjects (17%) and favored female expression (sex ratio, M1:F3) and right-side occurrence (68% of unilateral cases). Statistically significant associations were found between Mn.I2.C transposition and increased frequency of tooth agenesis (M3, p < 0.01; MnP2, p < 0.01) and peg-shaped maxillary lateral incisors (p < 0.0001). The results from this study and the analysis of 50 previously published cases provide evidence that Mn.I2.C transposition is a disturbance of tooth order and eruptive position probably caused by genetic influences. The Mn.I2.C anomaly likely results from genetic mechanisms similar to those responsible for occurrences of its associated dental anomalies, such as tooth agenesis and peg-shaped maxillary lateral incisors. In an appendix, clinical orthodontic management of Mn.I2.C transposition is discussed, based on treatment data derived from the study sample.

Adolescent↗
PubMed1998

Cardiac troponin T and cardiac troponin I: relative values in short-term risk stratification of patients with acute coronary syndromes. GUSTO-IIa Investigators.

We compared cardiac troponins T (cTnT) and I (cTnI) collected within 3.5 h of ischemic symptoms for predicting clinical outcomes in 770 patients. cTnT (cutoff > 0.1 microgram/L) and cTnI (cutoff > 1.5 micrograms/L) were concordant (both positive or negative) in 90.4% of patients. Among discordant results, 66 were cTnT positive and cTnI negative vs 8 who showed the reverse (P < 0.001). Five cTnT-positive and cTnI-negative patients died within 30 days; none who were cTnT negative and cTnI positive died. cTnT showed a slightly greater association (chi 2 = 18.0, P < 0.001) with 30-day mortality than cTnI (chi 2 = 12.5, P = 0.002). The area of the ROC curve for predicting 30-day mortality was significantly larger (Z = 2.08; P = 0.0375) for cTnT, at 0.68 [95% confidence interval (CI) 0.60-0.75], compared with cTnI, at 0.64 (95% CI 0.56-0.72). When cTnI and the electrocardiogram (ECG) were put in a logistic multiple regression model, cTnT added significant information (chi 2 = 8.03, P = 0.045); however, cTnI did not add to a model containing cTnT and the ECG (chi 2 = 0.84, P = 0.657). cTnT provided more information than cTnI for predicting 30-day mortality early after presentation with acute coronary syndromes.

Aged↗
PubMed1997

Assessment of coronary reperfusion after thrombolysis with a model combining myoglobin, creatine kinase-MB, and clinical variables. TAMI-7 Study Group. Thrombolysis and Angioplasty in Myocardial Infarction-7.

BACKGROUND: Several biochemical markers have been investigated for the noninvasive assessment of reperfusion after myocardial infarction. Because myoglobin is released very soon after myocardial injury and clears rapidly after reperfusion, it may prove to be an excellent marker of occlusion and reperfusion. METHODS AND RESULTS: We examined the relation between various myoglobin measures and Thrombolysis In Myocardial Infarction (TIMI) flow grade in 96 patients enrolled in a study of front-loaded thrombolysis who underwent 90-minute angiography. We also combined myoglobin measures with models that include clinical and creatine kinase-MB variables. The myoglobin level measured within 10 minutes of acute angiography showed the best overall performance and was used for later analyses. Of the clinical variables examined, only time from symptom onset to thrombolysis and chest pain grade at angiography discriminated among TIMI flow grades. Combining the 90-minute myoglobin level and these clinical variables showed a significant difference (P<.0001) between both TIMI 3 versus TIMI 0 through 2 and TIMI 2 or 3 versus TIMI 0 or 1 flow. When the 90-minute myoglobin level was added to an established predictive model containing clinical variables and creatine kinase-MB measures, its contribution remained significant (P=.044). The area under the receiver operator characteristic curve for this combined model was .88. CONCLUSIONS: A single myoglobin measurement obtained 90 minutes after the start of thrombolysis, combined with select clinical variables and creatine kinase-MB levels, enhances the noninvasive prediction of reperfusion after myocardial infarction.

Adult↗
PubMed1997

Absent molars.

Explore the source record for details and available documents.

Anodontia↗
PubMed1997

Ethylene provides positional information on cortical cell division but is not involved in Nod factor-induced root hair tip growth in Rhizobium-legume interaction.

Nod factors secreted by Rhizobium leguminosarum bv. viciae induce root hair deformation, involving a reinitiation of tip growth, and the formation of nodule primordia in Vicia sativa (vetch). Ethylene is a potent inhibitor of cortical cell division, an effect that can be counteracted by applying silver ions (Ag+) or aminoethoxy-vinylglycine (AVG). In contrast to the inhibitory effect on cortical cell division, ethylene promotes the formation of root hairs (which involves tip growth) in the root epidermis of Arabidopsis. We investigate the possible paradox concerning the action of ethylene, putatively promoting Nod factor induced tip growth whilst, at the same time, inhibiting cortical cell division. We show, by using the ethylene inhibitors AVG and Ag+, that ethylene has no role in the reinitiation of root hair tip growth induced by Nod factors (root hair deformation) in vetch. However, root hair formation is controlled, at least in part, by ethylene. Furthermore, we show that ACC oxidase, which catalizes the last step in ethylene biosynthesis, is expressed in the cell layers opposite the phloem in that part of the root where nodule primordia are induced upon inoculation with Rhizobium. Therefore, we test whether endogenously produced ethylene provides positional information controlling the site where nodule primordia are formed by determining the position of nodules formed on pea roots grown in the presence of AVG or Ag+.

Amino Acid Oxidoreductases↗