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Biomedical subjects

L Richards

Publications and source records attributed to L Richards.

At least 19 recordsLinked to original sources
PubMed2002

Accelerating flap maturation by vascular endothelium growth factorin a rat tube flap model.

The effect of exogenous vascular endothelium growth factor (VEGF) on the survival of the distal skin paddle with early pedicle division was studied in a rat tubed pedicle flap model. In part I, tubed pedicle skin flaps were created on the backs of 14 rats. The pedicle was divided after an interval of 3, 4, 5 or 7 days, and the survival area of each distal skin paddle was measured 5 days after the pedicle was divided. The percentages of survival were 0, 24.9%, 89.9% and 100%, respectively. In part II, tube flaps were created in 20 rats. In the experimental group, 2 ml of VEGF (50 microg ml(-1)) was injected into the recipient bed during tube flap creation in each rat. In the control group, 2 ml of saline was given. The tubed pedicle was divided 4 days after creation. The mean survival area of the distal skin paddle in the group treated with VEGF was 7.32 +/- 1.36 cm(2) (80.91%) at 5 days after pedicle division, which was of statistical significance when compared with the survival in the control group of 2.70 +/- 1.89 cm(2) (27.9%). The histology showed angiogenesis at the skin paddle-recipient bed interface following VEGF injection. These results demonstrate that the subcutaneous administration of VEGF into the recipient bed of the tube flap transfer can induce angiogenes is at the junction between the donor and the recipient bed, and improve skin paddle survival with early pedicle division.

Analysis of Variance↗
PubMed2001

Studies leading to the identification of ZD1839 (IRESSA): an orally active, selective epidermal growth factor receptor tyrosine kinase inhibitor targeted to the treatment of cancer.

This paper describes the development of the epidermal growth factor receptor tyrosine kinase inhibitor ZD1839 from a lead series of 4-anilinoquinazoline compounds. ZD1839 has suitable properties for use as a clinically effective drug and shows activity against human tumours. In particular, the use of pharmacokinetic data in the development of ZD1839 is discussed.

Administration, Oral↗
PubMed2001

Vascular grafts in the rat model: an anatomic study.

Vascular grafts in animal models have been used extensively in the microsurgical laboratory, and the rat offers an excellent source of graft to meet these needs. In this study, we compiled a list of vessels that were previously identified in experimental literature for use as vascular grafts in the rat model. We then dissected and measured both arterial and venous grafts taken from these sites in 12 adult rats. The surgical procedure for approaching each vascular graft was recorded. The diameter and harvestable length, the start and end points, and the number of branches of the graft were tabulated. We believe that these data will provide valuable insight applicable to the use of the rat vascular graft in microsurgical research and training.

Animals↗
PubMed2001

A study of occlusal variation in the primary dentition of Australian twins and singletons.

In this study, we quantified the extent of variation in different occlusal features of Australian children of European descent with complete primary dentitions, but no permanent teeth present in the mouth. The study group consisted of 412 individuals, aged between 3 and 7 years, including 70 monozygous (MZ) twin pairs, 68 same-sexed dizygous (DZ) twin pairs, 11 opposite-sexed DZ twin pairs, and 114 singletons. Occlusal traits, including inter-dental spacing, incisal overbite and overjet, arch breadth and arch depth, were obtained directly from dental casts or indirectly from photocopies or impressions of the casts. Descriptive statistics summarised the data and indicated that distributions were similar to those published for other populations. Univariate genetic analysis, using the structural equation modelling package Mx, was carried out on the quantitative data using the normal assumptions of the twin model. Genetic modelling indicated that a model incorporating additive genetic (A) and unique environmental variation (E) was the most parsimonious for interdental spacing, overbite, overjet and arch dimensions. Estimates of heritability for interdental spacing ranged from 0.62 to 0.81. Estimates for overbite and overjet were 0.53 and 0.28, respectively, and estimates for arch dimensions ranged from 0.69 to 0.89. These results indicated a moderate to relatively high genetic contribution to observed variation.

Australia↗
PubMed2001

Quantification of nerve tension after nerve repair: correlations with nerve defects and nerve regeneration.

This study tested the validity of a quantitative in vitro nerve-tension-measuring technique, by correlating the tension measurements with functional and morphologic assessments of nerve regeneration. Initially, harvested nerves were used in vitro to determine a K value for lateral displacement in this tissue. Next, this value was used to calculate the tension of nerve repair, following 0-, 3-, 6-, and 9-mm resections of nerves in groups of rats. After quantifying the nerve tensions following excision and repair, the authors determined a sciatic function index to evaluate functional recovery and axon diameter in the animals. Functional recovery was significantly impaired in animals with elevated measurable tension (9.04 +/- 0.74 g in a 6-mm defect, 27.76 +/- 8.86 g in a 9-mm defect), compared to animals with no or 3-mm excision and measured tension of 3.3 +/- 1.09 g or less. Increased tension was also associated with a significant decrease in axon diameter. This study succeeded, therefore, in quantitatively relating the elements of measured nerve tension, nerve gaps, functional nerve recovery, and morphologic regeneration. Quantification of nerve tension by lateral displacement in vivo offers a possible solution to clinical management of nerve gaps, when the choice between primary repair and nerve grafting is not a clear one.

Anastomosis, Surgical↗
PubMed2001

Treatment of facial angiofibromas of tuberous sclerosis by shave excision and dermabrasion in a dark-skinned patient.

Tuberous sclerosis is an inherited disease expressed clinically by the triad of mental retardation, seizures, and tuberous lesions. Facial angiofibromas, a common manifestation of tuberous sclerosis, can cause considerable cosmetic disfigurement, emotional distress, obstruction of vision, and hemorrhage. Treatment by shave excision, as the first step to remove the larger nodules, followed by dermabrasion, to smooth and sculpt the final surface, has been recommended as the most effective form of therapy. However, this method of treatment raises the question of risk for development of hypopigmentation in susceptible patients. The authors present their treatment of angiofibromas with shave excision and dermabrasion in a dark-skinned patient.

Adult↗
PubMed2000

Genetic analysis of deciduous tooth size in Australian twins.

Investigations of permanent dental crown size in twins and family groups indicate a high degree of transmissible control, but little is known about the relative contributions of genetic and environmental factors to variation in size of the deciduous (primary) teeth. Here, maximum mesiodistal and buccolingual crown dimensions of maxillary and mandibular primary teeth were measured from dental models of 602 individuals, including 99 monozygous (MZ) twin pairs, 81 dizygous (DZ) same-sex pairs, 41 DZ opposite-sex pairs, and 160 singletons. Data were subjected to univariate genetic analysis with the structural-equation-modelling package, Mx using the normal assumptions of the twin model. A model incorporating additive genetic (A) and unique environmental (E) variation was found to be the most parsimonious for all tooth-size variables. Estimates of heritability for deciduous crown size ranged from 0.62 to 0.91. This study shows that variation in deciduous crown size has a strong genetic component, similar to that observed in the permanent dentition. Further studies are required to determine whether the underlying genetic mechanisms are the same for both deciduous and permanent teeth.

Analysis of Variance↗
PubMed1999

Therapeutic interventions to improve upper extremity recovery and function.

In this article, the authors discuss motor control deficits in the upper extremity following stroke that interfere with the ability to perform daily life activities. The authors then review conditions of practice that promote learning of motor skills and how well several current intervention approaches adhere to these practice conditions. For each intervention approach, the authors discuss the evidence for effectiveness of the approach in facilitating motor skill gains.

Activities of Daily Living↗
PubMed1998

Vaccination with irradiated autologous melanoma cells engineered to secrete human granulocyte-macrophage colony-stimulating factor generates potent antitumor immunity in patients with metastatic melanoma.

We conducted a Phase I clinical trial investigating the biologic activity of vaccination with irradiated autologous melanoma cells engineered to secrete human granulocyte-macrophage colony-stimulating factor in patients with metastatic melanoma. Immunization sites were intensely infiltrated with T lymphocytes, dendritic cells, macrophages, and eosinophils in all 21 evaluable patients. Although metastatic lesions resected before vaccination were minimally infiltrated with cells of the immune system in all patients, metastatic lesions resected after vaccination were densely infiltrated with T lymphocytes and plasma cells and showed extensive tumor destruction (at least 80%), fibrosis, and edema in 11 of 16 patients examined. Antimelanoma cytotoxic T cell and antibody responses were associated with tumor destruction. These results demonstrate that vaccination with irradiated autologous melanoma cells engineered to secrete granulocyte-macrophage colony-stimulating factor stimulates potent antitumor immunity in humans with metastatic melanoma.

Cancer Vaccines↗
PubMed1998

Comparison of exposed dentinal surfaces resulting from abrasion and erosion.

The aim of this study was to compare the shape of exposed dentinal surfaces caused by abrasion and erosion with a view to developing a diagnostic clinical test. The study material consisted of 80 natural teeth and 129 dental models obtained from Australian Aborigines known to display considerable dental abrasion due to their diet, and dental models of 37 Caucasians diagnosed with dental erosion through detailed history and dietary analysis. Polyvinyl siloxane impressions were obtained of all occlusal surfaces with dentinal scooping in both the 'abrasion' and 'erosion' groups. All impressions were sectioned buccolingually through the deepest point of the scooped dentine, and then the profiles were photocopied at x2 magnification. The breadth and depth of dentinal profiles were measured to an accuracy of 0.1 mm, enabling ratios of depth:breadth to be determined, and the position of the deepest part of each scooped surface was recorded. The mean depth:breadth ratio of scooped dentine was significantly greater in the Aboriginal natural teeth (0.19 +/- 0.06, mean +/- SE) than in the Aboriginal dental models (0.15 +/- 0.04). Both Aboriginal natural teeth and models with abrasion showed significantly smaller ratios (p < 0.05) than the Caucasian models showing erosion (0.33 +/- 0.07). Furthermore, in the abrasion samples, the deepest region of the scooped dentine tended to be lingually placed more often in maxillary teeth but buccally placed more often in mandibular teeth (p < 0.05). These results indicate that scooped dentine on abraded occlusal surfaces of teeth displays significant differences in shape compared with that caused mainly by erosion.

Adolescent↗
PubMed1998

A randomized, controlled pilot study of a home-based exercise program for individuals with mild and moderate stroke.

BACKGROUND AND PURPOSE: Many stroke survivors have minimal to moderate neurological deficits but are physically deconditioned and have a high prevalence of cardiovascular problems; all of these are potentially modifiable with exercise. The purposes of this randomized, controlled pilot study were (1) to develop a home-based balance, strength, and endurance program; (2) to evaluate the ability to recruit and retain stroke subjects; and (3) to assess the effects of the interventions used. METHODS: Twenty minimally and moderately impaired stroke patients who had completed inpatient rehabilitation and who were 30 to 90 days after stroke onset were randomized to a control group or to an experimental group that received a therapist-supervised, 8-week, 3-times-per-week, home-based exercise program. The control group received usual care as prescribed by the patients' physicians. Baseline and postintervention assessments included the Fugl-Meyer Motor Assessment, the Barthel Index of Activities of Daily Living (ADL), the Lawton Scale of Instrumental ADL, and the Medical Outcomes Study-36 Health Status Measurement. Functional assessments of balance and gait included a 10-m walk, 6-Minute Walk, and the Berg Balance Scale. Upper extremity function was evaluated by the Jebsen Test of Hand Function. RESULTS: Of 22 patients who met study criteria, 20 completed the study and 2 refused to participate. The experimental group tended to improve more than the control group in motor function (Fugl-Meyer Upper Extremity: mean change in score, 8. 4 versus 2.2; Fugl-Meyer Lower Extremity: 4.7 versus -0.9; gait velocity: median change, 0.25 versus .09 m/s; 6-Minute Walk: 195 versus 114 ft; Berg Balance Score: 7.8 versus 5; and Medical Outcomes Study-36 Health Status Measurement of Physical Function: 15. 5 versus 9). There were no trends in differences in change scores by the Jebsen Test of Hand Function, Barthel Index, and Lawton Instrumental ADL Scale. CONCLUSIONS: This study demonstrated that a randomized, controlled clinical trial of a poststroke exercise program is feasible. Measures of neurological impairments and lower extremity function showed the most benefit. Effects of the intervention on upper extremity dexterity and functional health status were equivocal. The lasting effects of the intervention were not assessed.

Activities of Daily Living↗
PubMed1997

Activation without selection: parallel right hemisphere roles in language and intentional movement?

Because language and praxis each require the activation and selection of knowledge structures in long-term memory (MacKay, 1985, 1987), it is reasonable to consider whether hemisphere asymmetries for such processes span both domains. Language and skilled movement are thought to be strongly lateralized to the left hemisphere in most individuals. Yet, although recent evidence suggests that the right hemisphere also contributes to language use in context, few similar arguments have been made for the right hemisphere's involvement in motor planning. In this paper, we review some of the evidence for a right hemisphere role in language and action processing and propose that within each domain the right hemisphere activates a range of relevant knowledge structures without selection.

Affect↗
PubMed1997

Palatal rugae patterns in Australian aborigines and Caucasians.

The purpose of this study was to determine whether rugae patterns change with age and to compare the number and pattern of rugae in Australian Aborigines with those of Caucasians. For the longitudinal part of the study, serial dental casts of ten Aborigines, from 6 to 20 years of age, were examined and rugae patterns were recorded. To enable comparisons to be made between different ethnic groups an additional 100 dental casts of Australian Aborigines and 200 casts of caucasians, ranging in age from 13 to 17 years, were examined. Characteristics observed were number, length, shape, direction and unification of rugae. The length of rugae increased significantly with age but the total number of rugae remained constant. Thirty-two per cent of rugae showed changes in shape, while 28 per cent displayed a change in orientation. In contrast to studies suggesting that rugae move forward with age, the majority of Aboriginal rugae that changed direction moved posteriorly. Changes in rugae patterns have been assumed to result from palatal growth but alterations in pattern were observed in the Aboriginal sample even after palatal growth had ceased. The mean number of primary rugae in Aborigines was higher than in Caucasians, although more primary rugae in Caucasians exceeded 10 mm in length than in Aborigines. The most common shapes in both ethnic groups were wavy and curved forms, whereas straight and circular types were least common. There was a statistically significant association between rugae forms and ethnicity, straight forms being more common in Caucasians whereas wavy forms were more common Aborigines.

Adolescent↗
PubMed1997

The effect of gender and age at onset of depression on mortality.

BACKGROUND: Depression has a marked negative impact on geriatric patient mortality and morbidity. The risk factors and exact reasons for these effects are not well understood. METHOD: Seeking to better define the factors, we retrospectively analyzed the effects of gender and age at onset of affective disorder in a naturalistic study of 192 geriatric patients consecutively admitted to a large midwestern tertiary care center between 1980 and 1987 for the treatment of unipolar depression. RESULTS: After controlling for age at index admission, patients with an onset of depression before age 40 suffered significantly (p < .05) less mortality in follow-up than those with onset after age 40. When effects of gender are examined, the effects of age at onset are most profound in women, with a threefold increase in the rate of death in the cohort with age at onset of depression after 70 years when compared to those with onset before age 40. CONCLUSION: These results and those of others suggest that depressed elderly women with no previous history of affective disorder are at a markedly increased risk compared with elderly women with a history of affective illness for morbidity and mortality and that a significant proportion of elderly depressed patients are admitted to a psychiatric hospital for a depression that is secondary to serious medical illness.

Age Factors↗
PubMed1996

Pulmonary Nocardiosis in a patient with human immunodeficiency virus disease.

Nocardiosis is an uncommon disease which occurs most often in patients with impaired cellular immunity, yet is rarely reported in patients with Human Immunodeficiency Virus Disease. We present the first case of Nocardiosis seen at the University Hospital of the West Indies, occurring in a well-controlled diabetic with Human Immunodeficiency Virus Disease.

AIDS-Related Opportunistic Infections↗