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Biomedical subjects

L A Donaldson

Publications and source records attributed to L A Donaldson.

At least 19 recordsLinked to original sources
PubMed2003

Surgeon-controlled ultrasound-guided core biopsies in the breast--a prospective study and a new use for surgeons in the clinic.

AIMS: This study was to assess the accuracy of a surgeon performing ultrasound-guided core biopsies of the breast. METHODS: A prospective audit was carried out of 555 patients who underwent an ultrasound-guided core biopsy for a discrete solid mass [under 30 mm maximum diameter] by a single surgeon. The surgeon controlled the core biopsy needle and an ultrasonographer or radiologist provided the imaging with ultrasound. RESULTS: The accuracy of the surgeon in sampling the lesions [n = 555 core biopsies] was independent of the size of the lesion. This saved 272 patients having unnecessary surgery for a benign lesion. CONCLUSION: The practical involvement by the surgeon in breast ultrasound and performing core biopsies has reduced pressure on the breast radiologists, reduced the number of diagnostic surgical open biopsies and made the clinic more interesting for the surgeon. With increased surgical confidence in breast ultrasound, most small and impalpable cancers have pre-operative skin marking rather than X-ray wire localization prior to undergoing wide local excision. Trainee breast surgeons should be encouraged to learn breast ultrasound and core biopsies.

Adult↗
PubMed2001

The impact of supplemental feeding in young children on dialysis: a report of the North American Pediatric Renal Transplant Cooperative Study.

Supplemental feedings are commonly recommended for young children on dialysis but their effect on growth parameters and mortality has not been well documented. We report the results of a North American Pediatric Renal Transplant Cooperative Study (NAPRTCS) survey on the impact of supplemental feedings on growth and mortality in children < 6 years of age at dialysis initiation. Sixty-four nonsurvivors (NonS) were matched with 110 survivors (S) for age at dialysis initiation, primary renal disease, and year of entry into the NAPRTCS database. Questionnaires were completed by participating centers on 137 patients (51 NonS, 86 S). Supplemental feedings were given to 70% of patients and more commonly given to patients < 2 years of age compared to those 2-5 years of age at dialysis initiation (P < 0.001). Supplemental feedings were also more commonly given to patients with nonrenal disease in addition to renal disease compared to those with renal disease only (P < 0.001). In patients receiving supplemental feedings, the method of supplemental feeding was most commonly by nasogastric tube in patients < 2 years of age compared to those 2-5 years of age (P = 0.027). Supplemental feeding use was not different in S compared to NonS. There were no differences in height standard deviation score (SDS), weight SDS, or change in height or weight SDS in patients receiving supplemental feedings compared to those who did not. The height and weight SDS did not improve over time on supplemental feeds. In summary, despite the common use of supplemental feedings in young patients on dialysis, height, weight, and mortality remain unaffected. Prospective long-term evaluation of this therapy is needed to determine the effectiveness of supplemental feeding.

Body Height↗
PubMed2001

Lignification and lignin topochemistry - an ultrastructural view.

This review discuses the ultrastructural aspects of cell wall lignification and lignin topochemistry. Lignification results from the enzyme mediated polymerization of monolignols initiated by unknown factors (initiation sites) located at the corners of cells and in the middle lamella. Lignification results in the filling of pores within the carbohydrate matrix following a sequence from the outer regions of the wall towards the lumen. The amount and chemical characteristics of lignin vary across the cell wall, with the presence of reaction wood, and among cell types.

Cell Wall↗
PubMed2001

Relationship between underlying renal disease and renal transplantation outcome.

The purpose of this study is to better characterize graft and patient survival posttransplantation by examining survival according to underlying renal disease for all first-time renal allograft recipients in the United Network for Organ Sharing (UNOS) registry. From 1987 through 1996, the UNOS registry collected data on 23,838 living and 67,183 cadaveric renal transplantations. This investigation included all patients undergoing their first renal transplantation for whom the underlying cause of renal failure could be identified and categorized. Gross 1- and 3-year patient and graft survival according to underlying renal disease are included. In addition, a Cox proportional hazards model was created to analyze the effect of underlying disease on graft and patient survival after adjusting for comorbid conditions, demographics, and type of renal transplant (living versus cadaveric). The association between underlying disease and graft and patient survival is shown. Amyloidosis, sickle cell anemia, scleroderma, and radiation nephritis are associated with poor graft and patient survival. The risk ratio for patient mortality was more than twice that for immunoglobulin A nephropathy for a number of conditions, including analgesic nephropathy, amyloidosis, and both forms of diabetes mellitus.

Graft Survival↗
PubMed2001

Risk factors for mortality in infants and young children on dialysis.

The factors associated with a greater mortality risk in infants and young children undergoing dialysis have not been clearly determined. We report the results of a North American Pediatric Renal Transplant Cooperative Study designed to assess risk factors in patients aged younger than 6 years at initiation of dialysis therapy. Sixty-four nonsurvivors were matched with 110 survivors for age at dialysis initiation, primary renal disease, and year of entry onto the database. Questionnaires on 137 patients (51 nonsurvivors, 86 survivors) were completed by participating centers. Seventy-five percent (103 of 137 patients) of the patients were aged younger than 2 years at dialysis initiation; 42% (58 of 137 patients) had renal aplasia, dysplasia, and/or hypoplasia or obstructive uropathy; 62% were boys; and 62% were white. One-year patient survival rates were 83% in infants beginning dialysis at younger than 3 months of age, 89% in 3- to 23-month-olds, and 95% in 2- to 5-year-olds (P = 0.001). Comorbid nonrenal disease occurred in 37 of 51 nonsurvivors (74%) versus 46 of 84 survivors (55%; P = 0.027). Nonsurvivors had pulmonary disease and/or hypoplasia more often (14 of 37 nonsurvivors; 37.8% versus 8 of 46 survivors; 17.4%; P = 0.04). Oliguria or anuria was present in 23 of 33 nonsurvivors (70%) aged younger than 2 years versus 26 of 64 survivors (41%; P = 0.007). Infection accounted for 15 of 51 deaths (29.4%). In summary, these results suggest that age at dialysis initiation; presence of nonrenal disease, particularly pulmonary disease and/or hypoplasia; and oliguria or anuria in children aged younger than 2 years are identifiable as risk factors for mortality in these young patients.

Age Factors↗
PubMed2001

Follow-up of breast cancer: time for a new approach?

After treatment for breast cancer women are monitored for recurrent disease by means of routine hospital-based follow-up appointments. The aim of this study is to determine the efficiency of this system, by establishing how recurrence presents to our hospital. The study comes at a time of increasing pressure on breast clinics from new patient referrals and the need, since April 1999, to see all cases classified as urgent within two weeks of referral. A consecutive series of 643 patients who presented with operable breast cancer between 1992 and 1998 were reviewed. Details about the 108 patients who had locoregional or metastatic relapse were obtained from our breast cancer database and their clinical records. Full data were available on 104 patients: 77 (74%) were seen at expedited (interval) appointments and a further 18 (17.3%) drew attention to symptoms at a routine visit. Two cases of locoregional recurrence were revealed by surveillance imaging. Unsuspected disease, locoregional in all cases, was detected on examination in 7 (6.7%) patients. The median time to presentation of recurrence was 19 months for metastatic and 18 months for locoregional disease. Breast cancer recurrence usually presents to an interval clinic. Most cases that are confirmed following a routine review are already symptomatic. Long-term routine hospital follow-up after treatment for breast cancer appears inefficient and unnecessary. Following liaison with local general practitioners we propose to discharge patients from routine review after two years. Thereafter they will have scheduled appointments with their GPs with immediate access to specialist review in the breast care unit if required.

Breast Neoplasms↗
PubMed2000

Peritoneal dialysis catheter infections and peritonitis in children: a report of the North American Pediatric Renal Transplant Cooperative Study.

Peritonitis and catheter-related infections remain the two most-common causes of peritoneal dialysis (PD) treatment failure. To define the frequency and risks associated with exit site/tunnel infections (ESI/TI), as well as peritonitis, in pediatric patients on PD, we undertook a retrospective cohort study of patients initiated on PD in the North American Pediatric Renal Transplant Cooperative Study (NAPRTCS). We examined demographic data and PD catheter characteristics of 1,258 patients, aged < or = 21 years, initiated on PD from 1992 to 1997. We examined the frequency and complications of ESI/TI occurring within 30 days, 6 months, and 1 year of follow-up. For peritonitis episodes, we examined patient risk factors for peritonitis. Almost 11% of patients had an ESI/TI at 30 days, 26% between 30 days and 6 months, and 30% between 6 months and 1 year of follow-up. There was no increased risk of ESI/TI associated with patient age, race, or catheter characteristics. Peritonitis occurred in dialysis patients at a rate of 1 episode per 13.2 patient months. Proportional hazards regression analysis demonstrated that black race, single-cuffed catheters, and upward pointing exit sites were independent risk factors for peritonitis in the pediatric PD population. Patients with ESI/TI had twice the risk of those without these infections of developing peritonitis or needing access revision, and an almost threefold increased risk of hospitalization for access complications/malfunction. ESI/TI occurs commonly in pediatric PD patients. These infections cause significant morbidity, through risk of peritonitis, access revision, and hospitalization for catheter complications. Further study of potentially modifiable risk factors for ESI/TI in pediatric end-stage renal disease patients is warranted.

Catheterization↗
PubMed2000

Cognitive functioning in children on dialysis and post-transplantation.

We studied 124 children, 62 patient-subjects who had end-stage renal disease (ESRD) and 62 sibling-controls who closely matched the patient-subjects in terms of their ethnicity and their socioeconomic status, to discern whether children with ESRD would perform less well than their siblings on standardized achievement and intelligence quotient (IQ) tests, and to determine whether ethnicity would influence such results. The subjects were recruited from nine pediatric transplant and dialysis centers across the United States. Thirty-one subjects were white (Euro-American), 17 were African-American, and 14 were categorized as 'other'. The average age of the patient-subjects was 13.7 +/- 0.44 yr; and of the sibling-controls 13.7 +/- 0.38 yr. Most patients (61%) and siblings (84%) were in regular school classes, and most (87% and 92%, respectively) attended school full-time. The average IQ percentile rank for the patients was significantly lower than their siblings (31 +/- 4 vs. 44 +/- 5, respectively, with normal = 50). Patients tended to score lower on achievement tests compared with their siblings (spelling: 88.7 +/- 4 vs. 94.6 +/- 2; arithmetic: 88.5 +/- 2 vs. 94.0 +/- 2; reading: 91.9 +/- 2 vs. 100 +/- 3, respectively). Patients scores on achievement tests were influenced by age at diagnosis and by the mother/caregiver's lower achievement. Also, increased time on dialysis predicted lower scores on achievement tests. Neither dialysis/transplant status nor ethnicity significantly affected outcome. Our data suggest that ESRD, but not ethnicity or dialysis/transplant status, is a risk factor for lower IQ and academic achievement, especially in younger children, in children who spend more time living with ESRD, and in children whose mother's/caregiver's have lower educational levels.

Adolescent↗
PubMed2000

Fungal peritonitis in children receiving peritoneal dialysis: a report of the NAPRTCS.

BACKGROUND: The rarity of fungal peritonitis (FP) in children receiving chronic peritoneal dialysis (PD) has limited the amount of information available regarding the risk factors and management associated with this infection. METHODS: We reviewed all cases of FP occurring in patients entered into the dialysis registry of the NAPRTCS between January 1992 and May 1996 in an attempt to identify risk factors for infection, treatment strategies, and patient outcome data. A total of 1592 patients who were less than 21 years of age were enrolled in the dialysis registry and received maintenance PD during the period of observation. RESULTS: Of the total 1729 episodes of peritonitis in these patients occurring over 1732 patient-years of follow-up, FP accounted for 51 (2.9%) of the episodes. The patients on PD who developed FP were similar to those who did not develop FP with regard to race, gender, dialysis modality, and dialysis access characteristics. The overall peritonitis rate in patients who developed FP was 2.2 episodes per patient-year compared with 0.96 episodes per patient-year in the patients who did not develop this infection (P < 0.0001). In 25 (49%) cases, the FP was the patient's initial episode of peritonitis. Whereas recent antibiotic usage was present in 23 (56%) of 41 patients with FP, there was no statistically significant relationship (P = 0.26) noted between the presence of a gastrostomy and the development of FP. Candida species caused 33 of 42 (78.6%) FP episodes. Therapy consisted of PD catheter removal and Amphotericin B in the majority of patients. Six months after diagnosis, 27 patients remained on PD, twelve patients were receiving hemodialysis, and only three patients had died, in each case for reasons unrelated to their FP episode. CONCLUSION: FP is an infrequent cause of peritonitis in children receiving chronic PD. The presence of a gastrostomy does not appear to predispose patients to the development of this infection, and successful therapy most often consists of a combination of antifungal medication and dialysis catheter removal. The outcome of FP in children appears to be more favorable than in the adult dialysis population.

Adolescent↗
PubMed1999

Evaluation of pre- and posttransplant donor-specific transfusion/cyclosporine A in non-HLA identical living donor kidney transplant recipients. Cooperative Clinical Trials in Transplantation Research Group.

BACKGROUND: The beneficial effects of donor specific transfusion (DST) have become controversial in the cyclosporine era. This study was performed to evaluate the potential benefits of a new protocol for administering DSTs in the perioperative period. METHODS: Non-HLA identical living donor kidney transplant recipients were randomized prospectively to control or to receive a DST 24 hr before transplant and 7-10 days posttransplant. All patients received similar immunosuppression according to protocol. RESULTS: The protocol had 212 evaluable patients (115 transfused and 97 control). There were no differences in 1- and 2-year graft and patient survival, causes of graft failure, incidence and types of infection, repeat hospitalization, or the ability to withdraw steroids. Immunological hyporesponsiveness (by mixed lymphocyte culture) occurred more frequently in transfused patients (18%) than controls (3%) (P = 0.04). Blood stored for > or =3 days was associated with fewer early rejections than blood stored < or =2 days. Overall, class II antigen mismatches were associated with more rejection episodes than class I antigen mismatches. However, transfused patients, but not control patients, with more class I antigen mismatches were more likely to have rejections. CONCLUSIONS: Administration of DSTs by the method described had no practical influence on patient or graft survival for up to 2 years. However, donor-specific hyporesponsiveness was more common in transfused patients (18 vs. 3%). Longer follow-up will be needed to determine whether DST will be associated with long-term benefit.

Blood Preservation↗
PubMed1994

Characteristics of CD4+ T cells which transfer murine AIDS (MAIDS).

The murine acquired immunodeficiency syndrome (MAIDS) is caused in susceptible C57BL/6 (B6) mice by a defective murine leukemia virus (MuLV) and resembles human AIDS in several respects. The disease is characterized by hypergammaglobulinemia, polyclonal B cell activation, lymphadenopathy, and generalized immunosuppression within 5-8 weeks postinfection. The virus has been shown to infect B cells and macrophages and both T and B cells are required for MAIDS development. The manner in which T cells contribute to the disease process is not known. We report here that this retroviral infection leads to induction of a Thy-CD4+T cell subpopulation capable of transferring all the symptoms of MAIDS disease to normal B6 and B6 nu/nu. Essentially 100% of T cells recovered from B6 nu/nu mice, injected with CD4+ T cells from B6 MAIDS animal, is of the Thy-CD4+ phenotype. The proliferation of these T cells in culture and their ability to cause MAIDS in SCID mice is totally dependent on the presence of B cells. These T cells do not exhibit significant V beta restriction of their T cell receptors (TCR) and, by PCR analysis, have defective virus-specific sequences in the cellular genome. By several criteria, however, these cells do not produce the infectious virus. These results suggest that a B-cell-dependent population of CD4+ T cells from MAIDS animals, in the absence of detectable infectious virus production, has the ability to transfer MAIDS-like disease.

Acquired Immunodeficiency Syndrome↗
PubMed1993

T cell-B cell interaction: autoreactive T cells recognize B cells through a terminal mannose-containing superantigen-like glycoprotein.

Rat autoreactive T cells (ATs) recognize a membrane component(s) on syngeneic B cells in association with class II MHC antigens resulting in proliferation of ATs as well activation and differentiation of B cells. Results presented herein indicate that ATs recognize a stimulating antigen(s) SA, in association with class II MHC antigens, on the B cell surface. Our studies using inhibitors of carbohydrate and protein synthesis suggest that SA is a glycoprotein(s) with a high turnover rate but is not an immunoglobulin. Treatment of B cells with mannosidase abrogates their ability to stimulate AT proliferation. Furthermore, pretreatment of B cells with GNA (a lectin from Galanthus nivalis that reacts with free terminal-mannose residues on glycoconjugates) also inhibits their ability to stimulate ATs. However, these treatments do not affect the competence of B cells to stimulate an allogeneic MLR or present a conventional antigen to T cells. The frequency of CD4+ T cells proliferating in response to syngeneic B cells is very high (0.2-0.5%) and is in line with frequencies seen in "superantigen"-type responses. Moreover, T cell receptors expressed on ATs use mainly V beta 6, V beta 11, and V beta 8 regions. Based on these data, SA appears to be a fast turnover, terminal mannose-containing, superantigen-like glycoprotein on the B cell surface.

Animals↗
PubMed1991

Effects of cigarette smoke on the immune response. II. Chronic exposure to cigarette smoke inhibits surface immunoglobulin-mediated responses in B cells.

We have previously reported that chronic exposure of rats to cigarette smoke inhibits the antibody-forming cell (AFC) response to both T-dependent and T-independent antigens and may reflect B cell dysfunction. In this communication we extend these studies to show that T cell functions are normal in chronically smoke-exposed rats (SM) as judged by their responses to mitogens and "nominal" or alloantigens. While B cells from SM respond significantly to the B cell mitogen lipopolysaccharide (LPS), they fail to proliferate in response to anti-IgM (anti-mu) or to produce significant AFC response to sheep red blood cells. On the basis of the number of rosettes formed with trinitrophenylated (TNP) horse red blood cells; the frequency of TNP-binding cells (TNP-ABC) in the spleens of SM is comparable to sham control rats. However, the proliferation of TNP-ABC to TNP-Brucella abortus is significantly decreased in SM. These differences in SM B cell responses, i.e., between LPS and anti-mu/antigen, may to be related to the ability of LPS to bypass a portion of the membrane signal transduction cascade. These results suggest that cigarette smoke affects an early step(s) in the antigen-dependent B cell signal transduction pathway.

Animals↗
PubMed1990

T lymphocyte heterogeneity in the rat. III. Autoreactive T cells are activated by B cells.

Evidence has been presented to show that CD4+ autoreactive T cell lines (ATs)2 in the rat require periodic stimulation with syngeneic spleen cells for in vitro proliferation. This proliferation can be blocked by treatment of the stimulator (spleen) cells with mAb to Ia antigens. Although ATs are Ia+ and can activate the allogeneic MLR, they fail to be autostimulatory. Fractionation of the spleen cells revealed that ATs can be stimulated with B cells and not by macrophages, although the latter were efficient in several accessory cell functions, including antigen presentation, lectin-dependent T cell activation and allogenic MLR response. Moreover, B cells proliferated and differentiated in response to AT cells. These data are compatible with a model in which ATs respond to hitherto undetermined B cell membrane antigen(s) in association with MHC class II antigens. These results may have important implications in understanding autoimmune responses.

Animals↗
PubMed1990

Separation experiences in childhood and adult marital quality.

A relational model of the influence of childhood relationships on adult marital quality is proposed and tested in a family medical centre and a psychiatric outpatient population by a questionnaire of separation experiences, the Parental Bonding Instrument and the Locke-Wallace Short Marital Adjustment Test. This paper presents results from a psychiatric outpatient population that correspond with previously reported results on the family medical centre patients. The paper also presents data from both populations on the association of childhood separation experiences with adult marital quality. The presence or absence of self-reported childhood separation experiences was not associated with variations of marital quality in either population. The variation in other aspects of separation experiences similarly was not associated with marital quality. The association between representations of childhood experience and adult marital quality, found in a previous study of the family medical centre patients, was not found in the psychiatric outpatient population. The possible reasons for these findings are discussed.

Adult↗
PubMed1988

Effect of venous (gut) CO2 loading on intrapulmonary gas fractions and ventilation in the tegu lizard.

Studies were conducted to determine regional pulmonary gas concentrations in the tegu lizard lung. Additionally, changes in pulmonary gas concentrations and ventilatory patterns caused by elevating venous levels of CO2 by gut infusion were measured. It was found that significant stratification of lung gases was present in the tegu and that dynamic fluctuations of CO2 concentration varied throughout the length of the lung. Mean FCO2 was greater and FO2 less in the posterior regions of the lung. In the posterior regions gas concentrations remained nearly constant, whereas in the anterior regions large swings were observed with each breath. In the most anterior sections of the lung near the bronchi, CO2 and O2 concentrations approached atmospheric levels during inspiration and posterior lung levels during expiration. During gut loading of CO2, the rate of rise of CO2 during the breathing pause increased. The mean level of CO2 also increased. Breathing rate and tidal volume increased to produce a doubling of VE. These results indicate that the method of introduction of CO2 into the tegu respiratory system determines the ventilatory response. If the CO2 is introduced into the venous blood a dramatic increase in ventilation is observed. If the CO2 is introduced into the inspired air a significant decrease in ventilation is produced. The changes in pulmonary CO2 environment caused by inspiratory CO2 loading are different from those caused by venous CO2 loading. We hypothesize that the differences in pulmonary CO2 environment caused by either inspiratory CO2 loading or fluctuations in venous CO2 concentration act differently on the IPC. The differing response of the IPC to the two methods of CO2 loading is the cause of the opposite ventilatory response seen during either venous or inspiratory loading.

Animals↗