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Biomedical subjects

R Clark

Publications and source records attributed to R Clark.

At least 199 records · Page 11Linked to original sources

Compliance with public sector HIV medical care.

Despite the availability of free or low-cost public sector human immunodeficiency virus (HIV) health-care services, important inequities in utilization exist. This study examined two measures of compliance with HIV medical care: attendance of scheduled outpatient visits and use of the emergency room. Clients of two public HIV outpatient clinics were followed from time of health-care initiation to either death or the end of the study. The association of race, sex, age, and injection drug use (IDU) with these measures were examined in multivariate logistic regression. Models were adjusted for disease staging at time of entry and for length of follow-up time in clinic. Of 1824 clients followed, 15% failed to attend scheduled visits and 18.1% had at least one emergency room visit. Clients who missed visits were more likely to be African American, to have a history of IDU, and to have a CD4 cell count < 500/mm3 or an acquired immunodeficiency syndrome (AIDS)-defining opportunistic infection at entry. They were also more likely to have > or = 12 months of follow-up time in the HIV clinic, but were less likely to have entered into health care from an early intervention clinic. Clients who had at least one emergency room visit were more likely to be African American, female, IDU, and under 22 years of age; these clients were also more likely to have entered with CD4 < 200/mm3 or with an opportunistic infection, and to have > or = 12 months of follow-up in the clinic.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Natural language processing, lexicon and semantics.

While the design of a fully general procedure for semantico-pragmatic interpretation of natural language texts does not seem to be feasible with current scientific knowledge and technology, the more practical microworld based approaches lack generality and portability. A compromise between generality and practicality might lie in the use of an intermediate level of presentation ("pseudo-semantics"), which can be derived from syntactic representations and lexical information by means of a general procedure. Domain-dependent rules for semantico-pragmatic interpretation can then be applied to these representations, insulating syntactic processing from details of the application domain.

Humans↗

Ipsilateral breast tumor recurrence postlumpectomy is predictive of subsequent mortality: results from a randomized trial. Investigators of the Ontario Clinical Oncology Group.

PURPOSE: To determine whether ipsilateral breast tumor recurrence (IBTR) postlumpectomy was independently predictive of distant relapse and mortality in women with node negative breast cancer. METHODS AND MATERIALS: A randomized trial was conducted in Ontario between 1984 and 1989, in which 837 women with node negative disease who had undergone lumpectomy and axillary dissection were randomized to either postoperative radiation (40 Gy in 16 fractions to the whole breast, followed by a boost of 12.5 Gy in five fractions to the primary site), or no further treatment. A Cox proportional hazards regression analysis was performed for the endpoints mortality and distant relapse using the fixed covariates, treatment, age, tumor size, estrogen receptor status, progesterone receptor status, and nuclear grade; and the time dependent variable IBTR. RESULTS: The analysis was based on 799 patients for which all fixed covariate data was available. Median follow-up was 66 months. The cumulative rate of IBTR at 5 years was significantly greater for the no treatment group compared to the radiation group; 30% vs. 8% respectively (p < 0.0001). No difference was detected in overall survival between the treatment groups (p = 0.45). Significant independent predictors for mortality were nuclear grade, high vs. medium or low (relative risk (RR) = 2.28, p = 0.0001); and tumor size > or = 2 cm. vs. < 2 cm. (RR = 1.64, p = 0.01). In addition, IBTR predicted increased mortality (RR = 2.18, p < 0.0006). Similar results were observed for distant relapse. An IBTR within 1 year of surgery was associated with a higher risk of distant relapse and mortality. CONCLUSION: Local breast recurrence following lumpectomy is associated with an increased risk of distant relapse and death.

Breast Neoplasms↗

In vivo administration of insulin-like growth factor-I stimulates primary B lymphopoiesis and enhances lymphocyte recovery after bone marrow transplantation.

Recombinant human insulin-like growth factor-I (IGF-I) (100 micrograms/day) was infused by osmotic minipumps into mice to evaluate its effects on bone marrow B lymphopoiesis. IGF-I treatment resulted in a significant increase in the total number of bone marrow B lineage cells by 2 wk post-treatment in both normal, adult mice and animals that had been lethally irradiated and reconstituted with syngeneic bone marrow. Effects were still apparent at wk 3, even though pumps delivered IGF-I for only 14 days. In addition, the results confirm previous observations that IGF-I treatment results in an increase in numbers of splenic B cells and suggest that this is in part the result of stimulation of B cell proliferation in that organ.

Animals↗

Bicycle incidents in children--abdominal trauma and handlebars.

OBJECTIVES: To investigate the frequency and causes of bicycle related abdominal injuries in children and to examine the pattern of presentation. DESIGN: The study was a prospective study of bicycle related injury in children less than 15 years of age presenting to two paediatric hospitals (15 April-30 June 1992) and three general hospitals (1 August 1991-30 June 1992). RESULTS: In a series of 813 children, 41 sustained non-penetrating abdominal trauma due to a bicycle incident. In 21 cases, handlebar trauma was responsible. Ten of these children suffered life-threatening intra-abdominal injury. Handlebars with no plastic or foam covering of the metal ends were involved in all ten cases. In several of these cases, presentation to hospital was delayed and in others confirmation of the extent of injury took up to 48 hours. The length of hospital stay for those with significant intra-abdominal organ damage ranged from two to 156 days. CONCLUSIONS: Intra-abdominal trauma must be considered when dealing with children who are victims of bicycle trauma. Impact with handlebars may have occurred and some form of padded protection of handlebar ends is recommended unless their design can be suitably modified.

Abdominal Injuries↗

Effectiveness of bicycle helmets in preventing head injury in children: case-control study.

OBJECTIVE: To examine the risk of injury to the head and the effect of wearing helmets in bicycle accidents among children. DESIGN: Case-control study by questionnaire completed by the children and their carers. SETTING: Two large children's hospitals in Brisbane, Australia. SUBJECT: 445 children presenting with bicycle related injuries during 15 April 1991 to 30 June 1992. The cases comprised 102 children who had sustained injury to the upper head including the skull, forehead and scalp or loss of consciousness. The controls were 278 cyclists presenting with injuries other than to the head or face. A further 65 children with injuries to the face were considered as an extra comparison group. MAIN OUTCOME MEASURES: Cause and type of injury, wearing of helmet. RESULTS: Most children (230) were injured after losing control and falling from their bicycle. Only 31 had contact with another moving vehicle. Children with head injury were significantly more likely to have made contact with a moving vehicle than control children (19 (19%) v 12 (4%), P < 0.001). Head injuries were more likely to occur on paved surfaces than on grass, gravel, or dirt. Wearing a helmet reduced the risk of head injury by 63% (95% confidence interval 34% to 80%) and of loss of consciousness by 86% (62% to 95%). CONCLUSIONS: The risk of head injury in bicycle accidents is reduced among children wearing a helmet. Current helmet design maximises protection in the type of accident most commonly occurring in this study. Legislation enforcing helmet use among children should be considered.

Accidents, Traffic↗

Early history of ESPEN.

Since the European Society of Parenteral and Enteral Nutrition (ESPEN) is now well established as a major international scientific organisation, it may be of interest to recall how the Society came to be formed and how it evolved during its first few years. A chronological view will be given of the way ESPEN was organised during the early years, followed by a commentary on the development of its many roles.

Journal Article↗

A model of galactic cosmic rays for use in calculating linear energy transfer spectra.

The galactic cosmic rays (GCR) contain fully stripped nuclei, from Hydrogen to beyond the Iron group, accelerated to high energies and are a major component of the background radiation encountered by satellites and interplanetary spacecraft. This paper presents a GCR model which is based upon our current understanding of the astrophysics of GCR transport through interstellar and interplanetary space. The model can be used to predict the energy spectra for all stable and long-lived radioactive species from H to Ni over an energy range from 50 to 50,000 MeV/nucleon as a function of a single parameter, the solar modulation level phi. The details of this model are summarized, phi is derived for the period 1974 to present, and results from this model during the 1990/1991 CRRES mission are presented.

Cosmic Radiation↗

Recovery from acute ischaemic renal failure is accelerated by des-(1-3)-insulin-like growth factor-1.

1. Acute renal failure carries a high risk of morbidity and mortality, so there is a need for agents that minimize renal injury after an insult and that hasten repair. Insulin-like growth factor-1 is mitogenic for renal tubular cells; in normal kidneys it has haemodynamic effects and it is potently anabolic. We tested the theory that insulin-like growth factor-1 may be of use in the treatment of acute renal failure by administering recombinant des-(1-3)-insulin-like growth factor-1, a truncated form of insulin-like growth factor-1, which occurs naturally. Ischaemic renal failure was induced in normal rats by occluding both renal pedicles for 60 min. Then des-(1-3)-insulin-like growth factor-1 (0.8 mg day-1 kg-1) or vehicle was given by subcutaneous minipump for 7 days. The rats were weighed and bled daily and in one experiment were housed in metabolic cages and urine was collected. 2. Des-(1-3)-insulin-like growth factor-1 caused a lower and earlier peak in both serum creatinine and blood urea-nitrogen levels, and a more rapid and complete return toward basal values than in untreated animals. Also des-(1-3)-insulin-like growth factor-1 significantly increased creatinine clearance and reduced fractional excretion of filtered sodium. Besides these beneficial effects on kidney function, des-(1-3)-insulin-like growth factor-1 was anabolic as treated rats gained weight while control rats lost weight. The mortality in control rats was 28% compared with 6% in treated rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗

The efficacy of recombinant human granulocyte colony-stimulating factor and recombinant human granulocyte macrophage colony-stimulating factor in permitting the administration of higher doses of cyclophosphamide in a doxorubicin-cyclophosphamide combination. An NSABP pilot study in patients with metastatic or high-risk primary breast cancer. National Surgical Adjuvant Breast and Bowel Project.

Colony-stimulating factors (CSFs) shorten the duration of myelosuppression following chemotherapy and, thus, allow the administration of higher doses. This study evaluates the efficacy of granulocyte macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF) in allowing administration of high-dose cyclophosphamide in combination with doxorubicin. Ninety women with metastatic, locally advanced, or high-risk (> or = 10 positive nodes) breast cancer and no prior anthracycline treatment were given doxorubicin (60 mg/m2) with progressively increased doses of cyclophosphamide (1,200 mg/m2, 1,800 mg/m2, and 2,400 mg/m2). The first 60 patients received GM-CSF; the remaining 30, G-CSF. The maximum tolerated dose was not reached with 2,400 mg/m2 of cyclophosphamide. When compared to GM-CSF, G-CSF significantly reduced the duration of granulocytopenia (P < .001). No differences in duration of thrombocytopenia were noted. The results were not sufficiently consistent to indicate a trend toward reduction in rates of febrile neutropenia with one CSF versus the other. However, patients who received G-CSF were hospitalized less frequently than those receiving GM-CSF. With CSFs, high-dose cyclophosphamide in combination with doxorubicin can be safely administered on an outpatient basis. A shorter duration of granulocytopenia resulted from the use of G-CSF than from GM-CSF.

Antineoplastic Combined Chemotherapy Protocols↗

Immunological effects of insulin-like growth factor-I--enhancement of immunoglobulin synthesis.

In addition to its activity as a metabolic hormone and a regulator of somatic growth, insulin-like growth factor-I (IGF-I) has cytokine-like activities on lymphoid cells. A 14-day infusion of recombinant human (rh)IGF-I increased lymphocyte numbers in all the peripheral lymphoid organs examined. This increase was apparent for up to 3 weeks following cessation of hormone treatment. A second administration of rhIGF-I, given when the lymphocyte numbers in the rhIGF-I-treated mice had returned to control values, resulted in similar increases in the peripheral T and B cell populations. This increase in lymphocyte numbers had functional significance, since rhIGF-I-treated mice produced elevated antibody titres following primary or secondary antigen challenge compared with controls. In addition, when rhIGF-I-treated mice were immunized with a suboptimal dose of antigen they produced antibody titres which were equivalent to those generated by immunization with optimal doses of antigen. When examined in vitro, addition of rhIGF-I alone to cultures of splenocytes from antigen-primed mice stimulated immunoglobulin synthesis. These studies suggest that IGF-I produced locally by thymic and bone marrow stromal cells may be a natural component of B and T cell lymphopoiesis.

Animals↗

Response to specific Centruroides sculpturatus antivenom in 151 cases of scorpion stings.

Review was made of the symptoms, treatment and outcome of 151 cases of severe envenomation by the scorpion Centruroides sculpturatus treated with antivenom, 1988-1989. The most frequent symptoms were restlessness, nystagmus, paresthesiae, hypersalivation, fasciculation, blurred vision and dysphagia with an average of four symptoms. Medications before antivenom, given to about half of the subjects, included antihistamines, sedatives, analgesics and epinephrine. In 71% of patients, symptoms were relieved within 30 minutes of receiving one vial. Immediate hypersensitivity reactions occurred in 8%, but were generally mild. Skin tests had a sensitivity of 96% and specificity of 68%. Delayed reactions were not addressed. In conclusion, the antivenom appears safe and effective.

Adolescent↗