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Biomedical subjects

R Hinton

Publications and source records attributed to R Hinton.

14 recordsLinked to original sources
PubMed2000

Developmental dysplasia of the hip practice guideline: technical report. Committee on Quality Improvement, and Subcommittee on Developmental Dysplasia of the Hip.

OBJECTIVE: To create a recommendation for pediatricians and other primary care providers about their role as screeners for detecting developmental dysplasia of the hip (DDH) in children. PATIENTS: Theoretical cohorts of newborns. METHOD: Model-based approach using decision analysis as the foundation. Components of the approach include the following: PERSPECTIVE: Primary care provider. OUTCOMES: DDH, avascular necrosis of the hip (AVN). OPTIONS: Newborn screening by pediatric examination; orthopaedic examination; ultrasonographic examination; orthopaedic or ultrasonographic examination by risk factors. Intercurrent health supervision-based screening. PREFERENCES: 0 for bad outcomes, 1 for best outcomes. MODEL: Influence diagram assessed by the Subcommittee and by the methodology team, with critical feedback from the Subcommittee. EVIDENCE SOURCES: Medline and EMBASE search of the research literature through June 1996. Hand search of sentinel journals from June 1996 through March 1997. Ancestor search of accepted articles. EVIDENCE QUALITY: Assessed on a custom subjective scale, based primarily on the fit of the evidence to the decision model. RESULTS: After discussion, explicit modeling, and critique, an influence diagram of 31 nodes was created. The computer-based and the hand literature searches found 534 articles, 101 of which were reviewed by 2 or more readers. Ancestor searches of these yielded a further 17 articles for evidence abstraction. Articles came from around the globe, although primarily Europe, British Isles, Scandinavia, and their descendants. There were 5 controlled trials, each with a sample size less than 40. The remainder were case series. Evidence was available for 17 of the desired 30 probabilities. Evidence quality ranged primarily between one third and two thirds of the maximum attainable score (median: 10-21; interquartile range: 8-14). Based on the raw evidence and Bayesian hierarchical meta-analyses, our estimate for the incidence of DDH revealed by physical examination performed by pediatricians is 8.6 per 1000; for orthopaedic screening, 11.5; for ultrasonography, 25. The odds ratio for DDH, given breech delivery, is 5.5; for female sex, 4.1; for positive family history, 1.7, although this last factor is not statistically significant. Postneonatal cases of DDH were divided into mid-term (younger than 6 months of age) and late-term (older than 6 months of age). Our estimates for the mid-term rate for screening by pediatricians is 0.34/1000 children screened; for orthopaedists, 0.1; and for ultrasonography, 0.28. Our estimates for late-term DDH rates are 0.21/1000 newborns screened by pediatricians; 0.08, by orthopaedists; and 0.2 for ultrasonography. The rates of AVN for children referred before 6 months of age is estimated at 2.5/1000 infants referred. For those referred after 6 months of age, our estimate is 109/1000 referred infants. The decision model (reduced, based on available evidence) suggests that orthopaedic screening is optimal, but because orthopaedists in the published studies and in practice would differ, the supply of orthopaedists is relatively limited, and the difference between orthopaedists and pediatricians is statistically insignificant, we conclude that pediatric screening is to be recommended. The place of ultrasonography in the screening process remains to be defined because there are too few data about postneonatal diagnosis by ultrasonographic screening to permit definitive recommendations. These data could be used by others to refine the conclusions based on costs, parental preferences, or physician style. Areas for research are well defined by our model-based approach.

Decision Support Techniques↗
PubMed1999

Interactions between a single immunoglobulin-binding domain of protein L from Peptostreptococcus magnus and a human kappa light chain.

The placement of a tryptophan residue into a single Ig-binding-domain of protein L from Peptostreptococcus magnus has been used to examine the binding interactions between the binding domain and kappa light chains (kappa-chains). The fluorescence intensity of the mutant domain increases on the formation of a complex with kappa-chains. This has been used to determine the Kd of the complex under a range of conditions by using both pre-equilibrium and equilibrium methods. The Kd values determined for the complex with kappa-chains at a number of different pH values are very close to those obtained with the wild-type domain, indicating that the mutation has not substantially affected its binding properties. Examination of the reaction between the mutant domain and kappa-chains by stopped-flow fluorescence shows that complex formation takes place by two discrete, sequential processes. A fast bimolecular reaction, with a rate constant of 8.3x10(5) M-1. s-1 (at pH8.0 and 25 degrees C), is followed by a slow unimolecular process with a rate (1.45 s-1) that is independent of the concentration of the reactants. This suggests that a conformational change occurs after the initial encounter complex is formed. The dissociation of the complex at equilibrium occurs in a single process of rate 0.095 s-1 at pH8.0 and 25 degrees C. Stopped-flow CD studies show that a slow decrease in ellipticity at 275 nm occurs with a rate of 1.3 s-1 when wild-type protein binds to kappa-chains, suggesting that the conformational transition might involve a change in environment around one or more tyrosine residues.

Amino Acid Substitution↗
PubMed1997

Effects of exercise on fatigue, aerobic fitness, and disease activity measures in persons with rheumatoid arthritis.

The effects of 12 weeks of low-impact aerobic exercise on fatigue, aerobic fitness, and disease activity were examined in a quasi-experimental time series study of 25 adults with rheumatoid arthritis (RA). Measures were obtained preintervention, midtreatment (after 6 weeks of exercise), end of treatment (after 12 weeks of exercise), and at a 15-week follow-up. ANOVAS for repeated measures showed that those subjects who participated more frequently reported decreased fatigue, while those who participated less frequently reported an increase in fatigue. All subjects, on average, showed increased aerobic fitness and increased right and left hand grip strength, decreased pain, and decreased walk time. There were no significant increases in joint count or sedimentation rate. Significant improvements in measures at the 15-week follow-up also were found. Findings indicate that persons with RA who participate in appropriate exercises may lessen fatigue levels and experience other positive effects without worsening their arthritis.

Adult↗
PubMed1997

Type II collagen and TGF-betas in developing and aging porcine mandibular condylar cartilage: immunohistochemical studies.

Transforming growth factor-betas (TGF-betas) have been associated with the development and maintenance of articular cartilage. However, no studies have addressed their role in the postnatal development of mandibular condylar cartilage. This investigation represents the first immunohistochemical characterization of TGF-beta isoforms and type II collagen in porcine mandibular condylar cartilage from various age groups. Furthermore, it is the first description of possible age-related changes in the expression of these proteins during postnatal development of this tissue. Condylar cartilage was dissected from freshly harvested temporomandibular joints of newborn, 6-, 12-, 24-, and 36-month-old farm swine. TGF-beta1, TGF-beta2, TGF-beta3, and type II collagen were localized via standard immunohistochemical procedures. An immunoblot technique was employed to compare the relative amount of each protein present in the various age groups. Immunoreactivity was detected in mandibular condylar cartilage for all three isoforms of TGF-beta and for Type II collagen. All age groups demonstrated some evidence of immunostaining, primarily in the cytoplasm of cells from most zones of the cartilage. Immunoblot results indicated that TGF-beta isoforms had individualized patterns of expression. When newborn protein levels were taken as the baseline, TGF-beta1 demonstrated a significant increase at ages 24 and 36 months. TGF-beta2 significantly increased at 6, 12, 24, and 36 months (peak levels at 24 months; similar levels at 6, 12, and 36 months), whereas TGF-beta3 remained stable at all ages. Type II collagen demonstrated increases that paralleled the increased levels of TGF-beta1 and TGF-beta2 at 24 and 36 months.

Aging↗
PubMed1980

Unruptured cerebral aneurysms presenting as recurrent transient neurologic deficits.

Recurrent transient neurologic deficits were evaluated clinically in four patients. In three patients, the symptoms included recurrent transient homonymous hemianopia, episodic weakness and numbness of the left arm and leg, and recurrent sudden loss of speech and of strength in the right arm. In these three patients, the episodes were first thought to be transient ischemic attacks (TIAs). A fourth patient had repeated confusional spells, in which a recurrent musical theme excluded other thoughts. This was associated with dizziness and difficulty in naming. A partial complex seizure was thought responsible. In each of the cases the symptoms lasted less than 30 minutes and were not associated with loss of consciousness, headache, or stiff neck. Electroencephalogram (EEG), brain scan, lumbar puncture, and computed tomography (CT) scan were normal. In all patients, cerebral arteriography unexpectedly revealed an unruptured cerebral aneurysm. The locations of the aneurysms were appropriate to the symptoms, which remitted in the three patients treated surgically for the aneurysm. Although the pathophysiology is uncertain, an ischemic process may be implicated.

Adult↗
PubMedDate not supplied

A biomechanical analysis of solvent-dehydrated and freeze-dried human fascia lata allografts. A preliminary report.

UNLABELLED: This study compares the basic mechanical properties of two groups of commercially available fascia lata allografts processed by different means (solvent-dehydrated and sterilized via gamma radiation, and freeze-dried without secondary sterilization). The results reveal significantly (P less than 0.05) higher stiffness, higher maximum load to failure, and higher maximum load per unit width of graft with the solvent-dried as opposed to the freeze-dried fascia lata. Subsections of individual solvent-dried specimens were also more uniform in their mechanical properties than those of the freeze-dried allografts. CLINICAL RELEVANCE: Fascia lata is used as a graft material in a variety of orthopaedic procedures. Allograft fascia lata offers an increased cross-sectional area of material and eliminates the morbidity associated with the harvesting of autologous tissues. However, the structural uniformity of such large grafts has been questioned. Processing techniques used in the sterilization and storage of such grafts is varied and represents a potential source of variation in the mechanical properties of allograft specimens. The results of this study suggest that a commercially available solvent-dehydrated form of fascia lata provides a more suitable grafting material than freeze-dried specimens obtained from tissue banks.

Adult↗