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Biomedical subjects

D Richardson

Publications and source records attributed to D Richardson.

At least 91 records · Page 5Linked to original sources
PubMed1998

Percentage hypochromic red cells and the response to intravenous iron therapy in anaemic haemodialysis patients.

INTRODUCTION: Iron deficiency is commonly encountered in haemodialysis (HD) patients and may be overcome by i.v. iron therapy. We have examined the percentage hypochromic red cells (%HRC) for predicting response to i.v. iron in subjects with a low serum ferritin. METHODS: Prospective study of i.v. iron saccharate (trivalent iron 200 mg/week for 8 weeks) in anaemic (Hb < 10 g/dl) HD patients with serum ferritin < 100 microg/l despite oral iron therapy. Response to i.v. iron was assessed by comparing Hb at 0 and 8 weeks according to %HRC at baseline (0-3%, 4-9%, > or = 10%). Results are mean+/-1 SD. RESULTS: For all subjects (n=82), Hb and ferritin increased between 0 and 8 weeks (8.9+/-1.0 to 10.1+/-1.4, P<0.0001; 55+/-24 to 288+/-126, P<0.0001). Patients were stratified into three groups according to %HRC at baseline (0-3%, 4-9%, > or = 10%). Hb increased significantly in all three groups. The mean increase in Hb was greater (0-3%, 0.6+/-1.2; 4-9%, 1.2+/-1.0; > or = 10%, 1.6+/-1.4; P=0.02) and the proportion of patients showing a > or = 1 g/dl increase in Hb was greater (0-3%, 27%; 4-9%, 57%; > or = 10%, 67%; P=0.02) in those with the largest %HRC pre-treatment. CONCLUSION: Intravenous iron therapy is effective in improving Hb in anaemic HD patients with a low ferritin. However, the magnitude of this response and the proportion of patients responding is related to the percentage hypochromic red cells prior to treatment.

Anemia↗
PubMed1998

No relationship between emergency department activity and triage categorization.

OBJECTIVE: To examine the consistency of Australasian National Triage Scale (NTS) categorization in a large hospital ED, especially in relation to daily activity. METHODS: This was a prospective, observational study of the relationship between NTS category, presenting features, and disposition in a large Australian adult ED. The "admission rate" was defined as the percentage of presentations whose dispositions were recorded as admitted to hospital, transferred to another hospital for admission, or died in the ED. A "busy" weekday was defined as one during which > 140 presentations were recorded in the 24 hours from midnight. For a "busy" weekend day, a figure of 100 presentations in 24 hours was used. "Nonbusy" days were defined as those during which presentation numbers were less than or equal to these thresholds. RESULTS: Data describing triage and disposition were available for 94,681 presentations in the 2-year period, representing 100% of ED presentations. "Busy" weekday admission rates in the 5 triage categories were 93.2%, 67.6%, 43.6%, 15.4%, and 1.6%, respectively. "Nonbusy" weekday admission rates were 91.4%, 68.3%, 43.7%, 15.6%, and 2.0%. Weekend days had a higher admission rate in NTS category 4 and 5 patients, but none of the differences between "busy" and "nonbusy" days reached statistical significance at the 0.05 level. Admission rates varied according to the time of day of presentation and increased with age, but did not change significantly over the 2 years of the study. CONCLUSIONS: In this ED, triage categorization according to the Australasian NTS does not vary with daily activity and has been consistent over time. Further study in other settings is required, particularly to identify variation dependent on the presenting population.

Australia↗
PubMed1998

Sample size justification in phase III/IV clinical trials.

A sample size justification is often a key component in securing funding to conduct a clinical trial. Sample size computations typically require supplying values of parameters that are unknown and subject to misspecification. As an alternative, we advocate a power analysis approach based on a range of reasonable values for such parameters. We illustrate this approach in the context of a secondary stroke prevention trial.

Clinical Trials, Phase III as Topic↗
PubMed1998

Phase I/II trial of the safety and efficacy of shark cartilage in the treatment of advanced cancer.

PURPOSE: Patients with cancer and chronic inflammatory disorders have used shark cartilage (SC) preparations for many years. Preclinical studies that support their beneficial effects are scanty, and reports of clinical trials have been anecdotal. The proposed mechanisms of antitumor action include direct or indirect inhibition of angiogenesis. Because of the emerging use of SC as an alternative to conventional cancer therapy, this trial was launched to evaluate the safety and efficacy of SC. PATIENTS AND METHODS: Sixty adult patients with advanced previously treated cancer (breast, 16 patients; colorectal, 16 patients; lung, 14 patients; prostate, eight patients; non-Hodgkin lymphoma, three patients; brain, one patient; and unknown primary tumor, two patients) were enrolled. Eligibility criteria included confirmation of diagnosis, resistance to conventional therapy, objective measurable disease, life expectancy of 12 weeks or greater, Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2, no recent or concomitant anticancer therapy, no prior SC, and informed consent. Patients underwent evaluation of the extent of disease, quality-of-life score (Functional Assessment of Cancer Therapy-General [FACT-G] scale), and hematologic, biochemical, and selected immune function studies at baseline and after 6 and 12 weeks of SC therapy. The dose of SC was 1 g/kg daily orally in three divided doses. Standard criteria were used to evaluate adverse events and response. RESULTS: Ten of 60 patients were lost to follow-up(LTFU) or refused further treatment (RFT) before the 6-week evaluation and were not assessable for toxicity and response. Three patients with stable disease at 6 weeks were LTFU or RFT thereafter. Of the 47 fully assessable patients, five were taken off study because of gastrointestinal toxicity or intolerance to SC. Progressive disease (PD) at 6 or 12 weeks occurred in 22 and five patients, respectively. Five patients died of PD while undergoing SC therapy. No complete (CRs) or partial responses (PRs) were noted. Median time to tumor progression in the entire study population was 7+/-9.7 weeks (mean, 11.4 weeks; range, 3.7 to 45.7 weeks). Ten (20%) of 50 assessable patients, or 16.7% of the 60 intent-to-treat patients, had stable disease (SD) for 12 weeks or more. The median time to tumor progression was 27 weeks, the mean was 28.8+/-9.9 weeks, and the range was 18.6 to 45.7 weeks. In this subset, FACT-G scores improved in four patients, were unchanged in four patients, and declined in two patients. Twenty-one adverse events (grade 1, eight events; grade 2, seven events; and grade 3, six events) were recorded, 14 of which were gastroenterologic (nausea, vomiting, constipation). CONCLUSION: Under the specific conditions of this study, SC as a single agent was inactive in patients with advanced-stage cancer and had no salutary effect on quality of life. The 16.7% rate of SD was similar to results in patients with advanced cancer treated with supportive care alone.

Adolescent↗
PubMed1998

Race and the risk of fatal injury at work.

OBJECTIVES: This study examined employment patterns of African-American and White workers and rates of unintentional fatal injuries, METHODS: Medical examiner and census data were used to compare occupational fatality rates for African Americans and Whites in North Carolina and to adjust for racial differences in employment patterns. RESULTS: African Americans' occupational fatality rate was higher by a factor of 1.3 to 1.5. Differences in employment structure appear to explain much of this disparity. However, the fatality rate for African-American men would have been elevated even if they had had the same employment patterns as White men. CONCLUSIONS: inequalities in access to the labor market, unequal distribution of risk within jobs, and explicit discrimination are all potential explanations for racial disparities in occupational injury mortality. These conditions can be addressed through a combination of social and workplace interventions, including efforts to improve conditions for the most disadvantaged workers.

Accidents, Occupational↗
PubMed1997

Genomic sequence of a Lyme disease spirochaete, Borrelia burgdorferi.

The genome of the bacterium Borrelia burgdorferi B31, the aetiologic agent of Lyme disease, contains a linear chromosome of 910,725 base pairs and at least 17 linear and circular plasmids with a combined size of more than 533,000 base pairs. The chromosome contains 853 genes encoding a basic set of proteins for DNA replication, transcription, translation, solute transport and energy metabolism, but, like Mycoplasma genitalium, it contains no genes for cellular biosynthetic reactions. Because B. burgdorferi and M. genitalium are distantly related eubacteria, we suggest that their limited metabolic capacities reflect convergent evolution by gene loss from more metabolically competent progenitors. Of 430 genes on 11 plasmids, most have no known biological function; 39% of plasmid genes are paralogues that form 47 gene families. The biological significance of the multiple plasmid-encoded genes is not clear, although they may be involved in antigenic variation or immune evasion.

Biological Transport↗
PubMed1997

The complete genome sequence of the gastric pathogen Helicobacter pylori.

Helicobacter pylori, strain 26695, has a circular genome of 1,667,867 base pairs and 1,590 predicted coding sequences. Sequence analysis indicates that H. pylori has well-developed systems for motility, for scavenging iron, and for DNA restriction and modification. Many putative adhesins, lipoproteins and other outer membrane proteins were identified, underscoring the potential complexity of host-pathogen interaction. Based on the large number of sequence-related genes encoding outer membrane proteins and the presence of homopolymeric tracts and dinucleotide repeats in coding sequences, H. pylori, like several other mucosal pathogens, probably uses recombination and slipped-strand mispairing within repeats as mechanisms for antigenic variation and adaptive evolution. Consistent with its restricted niche, H. pylori has a few regulatory networks, and a limited metabolic repertoire and biosynthetic capacity. Its survival in acid conditions depends, in part, on its ability to establish a positive inside-membrane potential in low pH.

Antigenic Variation↗
PubMed1997

Magnetic source imaging evidence of sex differences in cerebral lateralization in schizophrenia.

BACKGROUND: It has been postulated that schizophrenia represents a disorder of anomalous cerebral lateralization. This study is a replication of earlier preliminary findings using a multichannel neuromagnetometer, suggesting altered lateralization in schizophrenia in male subjects, with an extension of the findings to female subjects. METHODS: We used magnetoencephalography-based magnetic source imaging to estimate the intracranial location of the 100-millisecond latency auditory-evoked field component (M100) in both left and right hemispheres of 20 patients with paranoid schizophrenia and 20 controls without schizophrenia. Neuroanatomical data were obtained by means of magnetic resonance imaging, from which we segmented and computed volumes of both total brain and left and right superior temporal gyri. RESULTS: Locations of M100 source were compatible with neuronal generators located in the transverse gyri of Heschl on the superior temporal gyri in both study groups; M100 sources were asymmetric in all the control subjects. The male patient subgroup exhibited significantly less asymmetry than the control group, while the female patient subgroup actually showed significantly more asymmetry. The male patient subgroup generally had smaller superior temporal gyri than the control group. No evidence of total brain volume differences was observed. CONCLUSIONS: Our findings support previous magnetoencephalography-based studies suggesting anomalous cerebral lateralization in schizophrenia. Further, in extending our studies to female patients, our data suggest that the nature of this anomaly is sex specific, a finding that, to our knowledge, has not previously been reported.

Adult↗
PubMed1997

Fatal agricultural injuries in North Carolina by race and occupation, 1977-1991.

Medical examiner reports and death certificates were reviewed for all fatal agricultural injuries (n = 228) that occurred on-the-job in North Carolina between 1977 and 1991. Data were collected on the decedents' age, gender, race, data and time of injury, means of injury, and occupation. Annual workforce estimates were derived from the 1980 and 1990 US Census of the Population. Overall, 54% of the fatal injuries were due to tractors. Farmers who suffered fatal injuries tended to be older (median age = 56 years) and Caucasian (87%), while farm workers who died on the job were younger (median age = 35 years) and more often African-American (60%). The crude mortality rate for farmers was 38 per 100,000 worker-years; the crude rate for farm laborers was 16 per 100,000 worker-years. Age-adjusted fatal injury rates were 2.5 times higher among African-American farmers than among Caucasian farmers; furthermore, between 1977 and 1991 the rate of fatal injury among African-American farmers increased an estimated 14.7% per year. African-American farmers in North Carolina have experienced rising rates of fatal injuries at a time when employment in the industry is declining due to consolidation of farm ownership and foreclosures of African-American owned farms. In order to address the growing racial disparity in farm fatalities, efforts need to be made to improve the conditions under which African-American farmers are working.

Accidents, Occupational↗
PubMed1997

From abandoned warehouse to life-saving facility, Pakro, Ghana. The Accra PMM Team.

PRELIMINARY STUDIES: Focus group discussions in Akwapim South District, Ghana, highlighted a lack of accessible health facilities as an important factor contributing to maternal deaths. INTERVENTIONS: In 1991, a health center was established by rennovating an abandoned warehouse. The center was equipped with beds, a refrigerator, a safe water supply, drugs and supplies. With the posting of a community health nurse from the Ministry of Health (MOH), it began functioning as a maternal and child health/family planning clinic. A senior nurse-midwife was posted in 1992 and obstetric services were offered. Starting in 1994, community interventions focused on reducing the delay in seeking care. RESULTS: An average of nine women with major obstetric complications were seen each 12-month period between 1992 and 1995. Many minor complications and non-obstetric ailments were also treated. COSTS: The material costs of establishing the health center amounted to US $12,550: 47% came from the community, 43% came from non-governmental organizations (NGOs), 7% from PMM and 3% from MOH. The costs of staff salaries were paid by MOH. CONCLUSIONS: It is possible to mobilize communities, government and NGOs to help provide emergency obstetric services. If emergency obstetric services are available, women will use them, even before the launching of community information and education campaigns.

Community Health Centers↗
PubMed1997

The maternity waiting home concept: the Nsawam, Ghana experience. The Accra PMM Team.

PRELIMINARY STUDIES: Focus group discussions with community members in Nsawam District, Ghana, identified poor roads, scarce transport and exorbitant fees for emergency transport as barriers to reaching the district hospital for treatment of an obstetric complication. INTERVENTIONS: To minimize delay in the event of a complication, a maternity waiting home (MWH) was established in Nsawam in 1994. One ward of an abandoned hospital was renovated and furnished for this purpose. The objective was to encourage women at high risk of obstetric complications to move to the MWH so they could be transferred to the hospital when labor began. RESULTS: Of 25 women referred to the MWH by health personnel over 12 months, only one complied, for one night. Focus group discussions with community members and hospital staff later revealed that cost and hardship of staying away from home, absence of health personnel, distance from hospital, desolate surroundings and lack of perceived need were reasons for poor utilization. COSTS: The intervention cost approximately US $10,500, shared approximately equally between the project and government. The main government contribution was the building. CONCLUSIONS: It is important to consult potential users not only to identify problems, but also to identify appropriate solutions. Careful 'market research' should be done before launching interventions.

Emergencies↗
PubMed1997

A simple program to create exact person-time data in cohort analyses.

BACKGROUND: Before disease rates can be calculated a tabulation of the length of follow-up for each person in the cohort has to be made. In complicated analyses such tabulations are often stratified by many characteristics, some which show no change with time, such as gender or year of birth, and some which do change with time, such as age or cumulative exposure. Available computer programs often restrict the way these tables can be made, particularly when handling time-dependent variables. METHODS: This paper presents a simple computer program which calculates the length of follow-up for each person in a study. RESULTS: Person-time data can be tabulated by a large number of variables using this method. This program is extremely flexible in the way that time-dependent variables can be created, can categorize observations by any unit of person-time, and will run on a range of platforms including a personal computer. CONCLUSIONS: This method should simplify the task of creating person-time data for analyses of disease rates in epidemiological studies.

Cohort Studies↗
PubMed1997

Radial forearm flap donor-site complications and morbidity: a prospective study.

One-hundred patients undergoing radial forearm flap reconstruction in the head and neck over a 2-year period were followed prospectively to assess complications and morbidity associated with the radial flap donor site. Eighty-six patients were available follow-up at 3 months and 74 at 1 year (49 fasciocutaneous, 25 composite). Partial loss of the donor-site skin graft occurred in 14 patients (16 percent), with exposure of tendons in 11 patients (13 percent). Delay in healing of the split-thickness skin graft at the donor site occurred in 19 patients (22 percent). Fracture of the radius occurred in 6 of 35 patients with composite flaps (17 percent). Superficial radial nerve sensation was reduced in 24 patients (32 percent) at 1 year. Ten patients (14 percent) reported cold intolerance, and 21 patients (28 percent) complained of poor aesthetic result. Function of the donor arm was restricted in 8 patients (16 percent) in the fasciocutaneous group, in 7 patients (36 percent) in the composite group without fracture, and in all patients who had a fracture of the radius following harvesting of composite flaps. Detailed measurements of forearm circumference, grip strength, pinch strength, and wrist movements showed greater reduction in these parameters in patients reporting restricted function compared with those reporting normal function. It is concluded that there is a low incidence of long-term morbidity associated with fasciocutaneous flaps and a higher incidence with composite flaps. Fracture of the radius results in reduced function in all cases.

Female↗
PubMed1997

Immune deficiencies in chronic intestinal pseudo-obstruction.

AIM: Chronic intestinal pseudo-obstruction has been associated with urinary disorders, myopathy, and ophthalmoplegia in adults and cholelithiasis in children. We observed a high percentage of total-parenteral-nutrition-dependent patients with pseudo-obstruction and recurrent infections requiring gammaglobulin infusions. METHODS: All records for 23 children with chronic intestinal pseudo-obstruction (10 females and 13 males, mean age 9.8 y +/- 4.9 y, range 4-24 y) referred for a nutritional evaluation from 1992 to 1995 were reviewed. Chronic intestinal pseudo-obstruction was diagnosed by clinical, radiographic findings and antroduodenal manometry. Intestinal full-thickness biopsies were performed in seven children. RESULTS: Hypogammaglobulinemia was diagnosed in 18 patients (78%): 16 patients had various immunoglobulin deficiencies and 2 had selective antibody deficiency. Intravenous gammaglobulin was administered in 14 patients. Other medical conditions affecting the children are summarized as follows: autonomic dysfunction in 10 patients (43%), recurrent hypoglycemia in 9 (39%), asthma in 9 (39%), cholecystitis in 7 (30%), low serum carnitine level in 6 (26%), urinary dysfunction in 6 (26%), pancreatitis in 5 (22%), behavioral problems in 5 (22%), myopathy in 2 (9%), idiopathic thrombocytopenia in 2 (8%), velopharyngeal insufficiency in 1 (4%), oculocutaneous albinism in 1 (4%), Pierre-Robin syndrome in 1 (4%), and protein C deficiency in 1 (4%). Munchausen syndrome was suspected in two patients. CONCLUSIONS: Chronic intestinal pseudo-obstruction appears to be associated with immune deficiencies. It is unclear if the immune deficiencies, intestinal pseudo-obstruction, and the other medical conditions have a common underlying etiology. Repeated infections may be due to impaired immune function in children with chronic intestinal pseudo-obstruction. We recommend screening for immune deficiencies in children with chronic intestinal pseudo-obstruction.

Adolescent↗