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Biomedical subjects

S Williams

Publications and source records attributed to S Williams.

At least 649 records · Page 36Linked to original sources
PubMed1986

Activation of the vascular system: a main mediator of periodontal fiber remodeling in orthodontic tooth movement.

The behavior and role of blood vessels and blood-borne cells in the process of the remodeling of the periodontal ligament (PDL) incident to experimental tooth movement was studied in rats. Particular interest was focused on areas of tension and of pressure with frontal bone resorption but without overt hyalinization. An increase of vascular activity occurred in the above mentioned situations. Extensive breakdown of collagen was observed in pressure areas with frontal resorption and in areas of tension concomitant with vascular invasion. Two patterns of fiber and bone remodeling were seen in areas of tension: intense vascular activity within the periodontal membrane and intense vascular activity inside the alveolar bone. Macrophages occurred consistently near blood vessels both in areas of tension and in areas of resorption. These are multipotent cells that obviously influence the remodeling process.

Alveolar Process↗
PubMed1986

The morphology of the potential Class III skeletal pattern in the growing child.

The aim of the present article was to identify morphologic characteristics in the craniofacial skeleton of the 11-year-old child that could indicate potential development of a Class III skeletal pattern. A radiographic material consisting of 24 children (13 girls, 11 boys) at an average age of 11 years 0 months, who in adulthood demonstrated a Class III skeletal pattern, was compared with a control group of 33 children (16 boys, 17 girls, average age 11 years 6 months) chosen retrospectively on the basis of Class I occlusion. The analysis was performed by means of both linear and angular variables and results are reported both as group means and individual analyses. No one morphologic trait indicative of potential Class III development could be isolated because the study clearly demonstrated the existence of different skeletal combinations. The development of the maxilla, both in size and position, was clearly demonstrated by the linear analysis to be an etiologic factor in Class III development. However, maxillary retrognathism was usually masked in the angular analysis because a reduction in length of the anterior base with subsequent effect on the position of point nasion was often seen in these cases. Mandibular prognathism was a frequent observation, although a true macrognathia was uncommon. In the majority of cases, mandibular prognathism was the result of an increase in the ratio between mandibular length and dorsal position of the glenoid fossa (articulare). The relative merits of angular and linear analyses are discussed in relation to the results presented.

Cephalometry↗
PubMed1986

An evaluation of the Malaise Inventory.

This paper reports some psychometric properties of the Malaise Inventory of Rutter and colleagues from a longitudinal study of a large sample of New Zealand mothers. Malaise scores were relatively stable over time and the scale showed good psychometric properties. The measure was also sensitive to potential sources of adversity in the backgrounds of the women. Some recommendations regarding a number of the questionnaire items are made.

Adult↗
PubMed1986

Clinical presentation of sickle cell-hemoglobin C disease.

Early symptoms were observed in a representative sample of 166 children with sickle cell-hemoglobin C disease diagnosed at birth. Symptoms were uncommon in the first year of life; in approximately 50% specific symptoms had developed by 5 years, but 22% remained without specific symptoms to 10 years. The age at presentation was significantly earlier in patients with low hemoglobin F levels, but was not influenced by heterozygous alpha-thalassemia-2. Painful crisis was the initial manifestation in 77% of the children; other symptoms included dactylitis (14%) and pneumococcal septicemia and acute splenic sequestration (4% each). The commonest nonspecific symptom was acute chest syndrome. The relatively mild early clinical course of sickle cell-hemoglobin C disease indicates that neonatal diagnosis does not have the same urgency as for homozygous sickle cell disease.

Acute Disease↗
PubMed1986

Timentin in the treatment of post-operative infections.

In an open study 50 patients were treated for a variety of infections with 3.2 g Timentin 6, 8- or 12-hourly for a mean period of six days. Timentin was clinically successful in 87% of patients assessed at the end of treatment of whom 95% remained cured or improved at a later follow-up. Bacteriologically Timentin was successful against 92% of organisms, including all 11 which were ticarcillin or ampicillin resistant. Side effects were reported in seven patients, the majority of which were minor local reactions at the site of infusion. This open study shows Timentin to be a safe and effective antibiotic for the treatment of infection.

Adolescent↗
PubMed1986

Renal revascularization for preservation of renal mass and function.

We advocate renal revascularization for preservation of renal mass and function. That revascularization can improve glomerular filtration and reverse vasculogenic renal failure appears well established. Proper selection of patients appears to be the key for achieving improvement of renal function after renovascular reconstruction.

Diagnosis, Differential↗
PubMed1986

IgG thyrotrophin receptor antibody activity in Graves' disease; a study of TSH agonist and antagonist activities by isoelectric focusing.

The distribution of TSH receptor antibody activity in the 7S and 19S fractions of Graves' sera has been re-evaluated. Serum fractions were obtained by gel filtration from 12 Graves' sera and assayed for TSH receptor binding activity in a radioreceptor assay. Thyroid stimulating activity was determined in a cultured porcine thyroid cell bioassay. In apparent contrast to the findings of Baker et al. (1983) TSH receptor binding activity was confined to the 7S gel filtration fraction, containing IgG, and was not detected in the 19S fraction, containing IgM. Similarly thyroid stimulating activity was detected only in the 7S fraction. 7S fractions from seven Graves' sera were fractionated by isoelectric focusing and the fractions analysed for TSH receptor binding activity and TSH agonist and antagonist activities. Five of the IgGs showed TSH agonist activity and in all five, the peak thyroid stimulating activity (measured by stimulation of cyclic AMP release from isolated porcine thyroid cells) was in fractions with a pI of between 8.0 and 9.5. In four of these five IgGs, TSH receptor binding activity showed similar isoelectric distribution to the thyroid stimulating activities. High levels of TSH receptor binding activity without associated TSH agonist or antagonist activity were however observed in some isoelectric fractions of the fifth stimulating Graves' IgG studied. All the isoelectric fractions from the fifth IgG with thyroid stimulating activities contained TSH receptor binding activity. Two of the Graves' IgGs showed TSH antagonist activity and both the TSH receptor binding and TSH antagonist activities of these IgGs showed similar isoelectric distribution with the peak activities at a pI of around 9.0. Consequently, it was not possible to separate TSH agonist or TSH antagonist activities from TSH receptor binding activity in seven Graves' sera by isoelectric focusing although in one IgG several isoelectric fractions contained isolated receptor binding activity. These findings are in keeping with the hypothesis that the biological activities of Graves' IgGs are intimately related to their ability to bind to the TSH receptor.

Animals↗
PubMed1986

Sleep in middle childhood--a longitudinal study of sleep problems in a large sample of Dunedin children aged 5-9 years.

Complaints of sleeping difficulties in a large group of New Zealand children were studied prospectively over four years from 5 to 9 years of age. No association was found between sleeping difficulties and the sex, intelligence, or educational attainments of the child. Mothers who described their child as anxious or who were poor sleepers themselves tended to report sleeping problems in their child more frequently. There was no association between sleeping problems and teacher ratings of behaviour problems. Children who reported sleep problems also tended to report other problems. There was low agreement between parents and children. Only 0.3% of the total sample had a problem which persisted over the whole period.

Analysis of Variance↗
PubMed1986

The relationship between specific reading retardation, general reading backwardness and behavioural problems in a large sample of Dunedin boys: a longitudinal study from five to eleven years.

Parent and teacher reports of behaviour problems were obtained at ages 5, 7, 9 and 11 years for three groups of boys: specific reading retarded (N = 18), general reading backward (N = 22), and those with no severe reading disability (N = 436). At school entry, both groups of reading disabled boys were reported as having more behaviour problems, and the level of problems increased during their early school years. The results suggest that behaviour problems pre-date reading disability, while reading failure further exacerbates the existing problem behaviour.

Aggression↗
PubMed1986

Prognostic factors for favorable outcome in disseminated germ cell tumors.

Between 1978 and 1982, 180 patients from Indiana University (Indianapolis) were entered on the Southeastern Cancer Study Group (SECSG) protocol 78 GU 240, a randomized comparison of cisplatin, vinblastine, and bleomycin (PVB) v PVB plus doxorubicin induction chemotherapy regimens, with a second randomization to maintenance vinblastine v no further therapy. One hundred forty-eight of these patients obtained a favorable response to chemotherapy, defined as a complete response (CR) or a surgical resection of teratoma. The prognostic significance of various patient characteristics was investigated using the logistic regression model. Two classifications for the extent of disease were considered: the Indiana staging system and the M.D. Anderson (MDA) staging system. The Indiana staging system had the greater prognostic significance. This staging system allowed the population to be split into three groups (minimal, moderate, advanced disease) in which the observed proportions of favorable responders were 99%, 90%, and 58%, respectively. Within the advanced group, the number of elevated tumor markers subdivided these patients into three groups, with the observed proportions of favorable responders being 73%, 65%, and 45%. The Indiana and MDA staging systems were subsequently prospectively used in SECSG protocol GU 81 332, a study randomizing patients to remission induction therapy with PVB v cisplatin, VP-16, and bleomycin. The prognostic value of the Indiana staging system was prospectively validated in this study.

Adolescent↗
PubMed1986

Three experimental designs testing orthopedic casting material strength.

Three methods for testing the comparative strength of orthopedic casts have been considered. Two of the tests, three-point-beam-bending and diametral compression, were expected to yield information about "material" strength, and a third simulated an actual cast yielding information about "structural" strength. In one study using these three methods, differences in strength were detected in the material tests, but not in the structural test. Thus, the authors believe that tests of material strength alone are insufficient to establish clinically relevant differences between the strength of orthopedic casts. Adequate testing must include structural tests like the cast-cylinder test described in this article if meaningful and clinically relevant conclusions are to be drawn regarding the comparative strength of the actual cast. Since both the three-point-beam-bending and diametral compression tests produced essentially the same results, both tests are probably not necessary. However, each of these two tests does serve to substantiate the results of the other.

Casts, Surgical↗
PubMed1986

N-acetylprocainamide's antiarrhythmic action in patients with ventricular tachycardia.

Antiarrhythmic properties of N-acetylprocainamide, an active metabolite of procainamide, were studied in 15 patients who presented with a cardiac arrest or documented sustained ventricular tachycardia. Programmed electrical stimulation studies were performed. All patients tested had inducible ventricular tachycardia by programmed electrical stimulation techniques while off all antiarrhythmic therapy. Patients were then tested on procainamide 1000 mg administered intravenously, and ventricular tachycardia could be provoked in 8 of 10 patients. Twenty-four to 36 hours later, N-acetylprocainamide was administered, intravenously, and programmed stimulation was performed after 20 minutes. N-acetylprocainamide did not significantly change heart rate, mean arterial blood pressure, electrocardiographic intervals, A-H or H-V conduction times. N-acetylprocainamide prevented ventricular tachycardia induction in 6 of 15 patients. The mean serum N-acetylprocainamide levels in the group protected was 15.7 +/- 4 micrograms/ml and 16.2 +/- 4 micrograms/ml in the group not protected. These 6 patients were discharged on N-acetylprocainamide 1.5 grams orally every 8 hours. Three patients have been maintained on chronic N-acetylprocainamide every 8 hours. Three patients have been maintained on chronic N-acetylprocainamide therapy (6 +/- 2 months), two patients had breakthrough ventricular tachycardia on follow-up Holter monitoring and alternative therapy was given. N-acetylprocainamide has antiarrhythmic efficacy in preventing induction of ventricular tachycardia by programmed electrical stimulation in a high risk group of patients. On chronic oral therapy, N-acetylprocainamide appears to be well tolerated with antiarrhythmic efficacy that may be enhanced with further upward dose titration.

Acecainide↗
PubMed1986

Assessing child-rearing style in ecological settings: its relation to culture, social class, early age intervention and scholastic achievement.

Middle- and lower-class black and white adolescents were observed interacting with their mothers during a discussion of seven child-rearing problems. Maternal references to a range of disciplinary measures were identified, analyzed, and related to the subjects' scholastic performances concurrently. A factor analysis of process measures confirmed earlier findings based on self-report data concerning parental disciplinary style. Low SES mothers who participated in an early-age intervention and upper middle-class mothers tended to be less punitive than those in the low SES untreated group. Black mothers were less permissive than those in the white group. Parental disciplinary style was found to be significantly related to school performance. The results are discussed in terms of the development of methodological procedures for interaction analysis in semi-structured, ecological research, for the evaluation of process variables in early-age intervention follow-ups and theory relating disciplinary style to intellectual development.

Achievement↗