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Biomedical subjects

A Mitchell

Publications and source records attributed to A Mitchell.

At least 55 records · Page 3Linked to original sources
PubMed2000

Absence of the left portal vein: a difficulty for reduction of liver grafts?

BACKGROUND: Absence of the portal bifurcation is exceptional and characterized by an absent extrahepatic portal vein bifurcation, the right portal vein only being at the porta hepatis. There is no extraparenchymal left portal vein. This may represent a problem in liver splitting, reduction, and living related transplantation. METHOD: A case was encountered during reduction of a cadaveric liver allograft to a left lateral segmental graft from a 40-kg cadaveric donor to a 15-kg recipient. The portal venous inflow was reconstructed with a vein graft via a novel extrahilar approach to the left portal vein at the umbilical fissure. RESULTS: This graft was used successfully in a 3-year-old child requiring transplantation for a failed Kasai operation for extrahepatic biliary atresia. The child is now well, 1 year posttransplant, after an uneventful postoperative course with good portal flow within the graft. CONCLUSION: The situation of an absent left portal vein extrahepatic course should not preclude splitting or reduction procedures. The innovative technical solution, we propose, should add to the armamentarium of the liver transplant surgeon contemplating a left lateral segmental graft for the paediatric liver transplant recipient.

Biliary Atresia↗
PubMed2000

En block combined reduced-liver and small bowel transplants: from large donors to small children.

BACKGROUND: The critical shortage of size-matched donor organs for infants and small children in need of combined liver and intestinal transplantation has lead to long waiting times and a high risk of dying before transplantation. Utilizing grafts from larger donors could alleviate this problem, but using larger composite grafts in small children has been challenging and unsuccessful in the past. METHODS: We conducted a pilot study for evaluating the results of transplanting into small recipients a composite graft (reduced-size liver and whole small bowel, including duodenum and pancreas head) procured from large donors. Liver size reduction was performed ex situ using the extrahilar approach, which leaves the liver hilum untouched. Straightforward implantation of the graft was performed by simple, two-step vascular anastomoses. The preservation of the donor duodenum in continuity with the combined graft avoided the need for biliary reconstruction, thus preserving maximal bowel length for gut continuity restoration in the recipient. RESULTS: Two children, weighing 7.6 and 9.8 kg, respectively, underwent transplantation of a composite graft procured from donors weighing 35 kg. Their waiting time (68 and 97 days, respectively) was shorter compared with our previous experience with conventional techniques. Both are currently alive and well, at home and on full enteral feeds, 15 and 11 months after transplantation, respectively. CONCLUSION: This new technique has extended the range of possible donors for small candidates waiting for combined grafts and was successful in two patients. It should be considered for small recipients in the future.

Adolescent↗
PubMed2000

Mouse lymphoma thymidine kinase locus gene mutation assay: International Workshop on Genotoxicity Test Procedures Workgroup Report.

The Mouse Lymphoma Assay (MLA) Workgroup addressed and reached consensus on a number of issues. Discussion focused on five areas: (1) acceptable assay versions; (2) cytotoxicity measure; (3) 24-hr treatment; (4) microwell colony counting and sizing; and (5) data acceptability/statistical analysis. Although the International Conference on Harmonisation (ICH) indicated a preference for the microwell over the soft agar method, all of the workgroup members agreed that both versions of the MLA are equally acceptable. The workgroup agreed that it is desirable for both assay versions to use the same measure of cytotoxicity to define the acceptable and required concentration range. Currently, laboratories using the microwell version use the relative survival (RS) determined by cloning immediately after the treatment. Laboratories using the soft agar method do not obtain an RS but use the relative total growth (RTG), a combination of the relative suspension growth (RSG) during the expression period and the relative cloning efficiency determined at the time of mutant selection. The workgroup agreed to investigate the RSG, the RS, and the RTG and to develop further guidance. In the interim, the workgroup reached consensus that the RTG be used as the standard measure of cytotoxicity. The ICH recommended a 24-hr treatment in the absence of S9 when negative results are obtained with short (3-4 hr) treatments. The workgroup agreed to retain this requirement but acknowledged that more data are needed prior to making final recommendations concerning the need for and the specific protocol for the 24-hr treatment. Environ. Mol. Mutagen. 35:185-190, 2000 Published 2000 Wiley-Liss, Inc.

Animals↗
PubMed2000

Antioxidative activities of aroma extracts isolated from natural plants.

Natural leaves and flowers containing numerous aroma chemicals are widely used in aromatherapy since ancient times. In addition to their pleasant smells, aroma chemicals might have some beneficial health effects. Aroma extracts, isolated from coffee beans, soybeans, and mung beans by steam distillation under mild conditions (55 degrees C and 85 mm Hg) were examined for their antioxidative activities. The inhibitory effect of these extracts toward hexanal/hexanoic acid conversion was measured in the testing solution over prolonged time periods. The inhibitory effects of these extracts toward malonaldehyde formation from lipids oxidized by Fenton's reagent were also measured. The antioxidative activity of these extracts, in particular coffee bean extract, was consistent with that of BHT or alpha-tocopherol (vitamin E). Soybeans and mung beans extract contained maltol, which inhibits hexanal oxidation significantly. Eugenol, which is one of the major constituents of mung bean extract, exhibited potent antioxidative activity in an aldehyde/carboxylic acid assay. Antioxidants such as eugenol and maltol may play an important role in the pharmaceutical activities of natural plant extracts used for aromatherapy.

Aldehydes↗
PubMed2000

Phylogenetic utility of the nuclear gene dopa decarboxylase in noctuoid moths (Insecta: Lepidoptera: noctuoidea).

Phylogenetic utility for the nuclear gene encoding dopa decarboxylase (DDC), little used in systematics, was recently demonstrated within the noctuid moth subfamily Heliothinae. Here we extend the test of the utility of a 709-bp DDC fragment to deeper levels, analyzing 49 species representing major groups across the superfamily Noctuoidea. Parsimony, distance, and maximum-likelihood analyses recover all or nearly all of a set of "test clades" supported by clear morphological synapomorphies, spanning a wide range of taxonomic levels. DDC also upholds a recent proposal that the Noctuidae are paraphyletic. Nt3 contributes a majority of the signal and recovers the basal split between Notodontidae and all other noctuoids, despite a plateau of nt3 divergence at this level. However, nonsynonymous changes also support groups at all levels, and in contrast to nt3, amino acid divergence shows no plateau. The utility of DDC promises to extend back to the early Tertiary and Cretaceous, a time span for which few suitable genes have been identified.

Animals↗
PubMed2000

[Endoscopic excision of extra-adrenal pheochromocytomas (paragangliomas)].

We describe the successful endoscopic removal of six extra-adrenal pheochromocytomas in three patients. One neoplasia was located retrocavally, two between the aorta and vena cava, two by the para-aortal, and one by the parailiacal. The tumors were removed by the posterior retroperitoneoscopic or by the anterior laparoscopic approach, respectively. The intraoperative and postoperative courses were uneventful.

Adrenal Gland Neoplasms↗
PubMed2000

Differential protective effects of neurotrophins in the attenuation of noise-induced hair cell loss.

The protective efficacy of neurotrophin-3 (NT-3) and brain-derived neurotrophic factor (BDNF) at 1 or 10 microg/ml was assessed in guinea pigs exposed to 4 kHz octave band noise at 115 dB SPL for 5 h. BDNF, NT-3 or artificial perilymph was delivered to the scala tympani via a mini-osmotic pump, beginning 4 days prior to noise exposure and continuing for 1 week post-exposure. Protection was assessed physiologically by the change in auditory brainstem response (ABR) threshold, and histologically by outer hair cell (OHC) survival. There was a statistically significant increase in OHC survival and a decrease in ABR threshold shift in animals receiving NT-3 at a concentration of 10 microg/ml. In animals receiving 1 microg/ml NT-3, there was a significant increase in OHC survival in the first row of OHC, but no significant change in ABR threshold, relative to control animals. In animals treated with BDNF, no significant functional or histological protection was observed. The protection afforded by NT-3 (10 microg/ml) treatment was similar in magnitude to that reported previously with glial cell line-derived neurotrophic factor and suggests that several factors may be involved in the protective response.

Animals↗
PubMed2000

Determinants of bone density and prevalence of osteopenia among female runners in their second to seventh decades of age.

This is a cross-sectional study of spine and hip bone density (BMD) in 124 female athletes, aged 16-68 years, who trained for at least 3 hs/week. The aim was to document the effects of competitive running on BMD in women over a broad age range. Thirty-three subjects, aged <35 years, were currently oligo- or amenorrheic and, of the 50 who were >40 years, and who were now menstruating normally, 13 had previously been oligo- or amenorrheic. Fifty-two women <50 years of age had never had disturbed menses. Twenty-four older women were postmenopausal. Women who had never had menstrual disturbance had significantly increased bone density at the lumbar spine, femoral neck, and femoral trochanter, as compared with young normal European reference data (range from +0.4 population SD or T-score units to +1. 2 units according to measurement site and age group). In contrast, young amenorrheic or oligomenorrheic runners had reduced bone density, particularly at the spine (mean T score < -1.1), whereas older runners who previously had disturbed menses, but were now menstruating normally, had bone densities that were similar to sedentary young controls. Postmenopausal runners had bone density values that differed little from sedentary postmenopausal controls matched for time since menopause, after adjusting for the runners' lower body weight. Bone density outcomes were related to candidate explanatory variables. After taking into account the other variables, age, per se, influenced only the femoral neck and Ward's area. Years since last exposure to estrogen (at premenopausal levels) was an important determinant of bone loss at both hip and spine. Body weight had a beneficial influence on the femoral neck region, whereas (in contrast) height had a positive influence on the lumbar spine. Months of breastfeeding (totaled for all children) had a modest, positive influence, which was larger in the femoral measurement sites. There was no evidence of an effect of calcium intake or percent body fat on BMD at any site independent of these other effects. It is concluded that, with the consistent presence of normal premenopausal estrogen levels, running at least 3 hs/week substantially improves bone density, particularly at the proximal femur. This beneficial effect is reversed in the absence of the consistent past and current presence of normal menstrual function. There was no clear benefit of running seen on BMD in postmenopausal women, but premenopausal veteran athletes who started running after the age of 30 years were not disadvantaged compared with early starters.

Adolescent↗
PubMed2000

Caps and cancer.

Explore the source record for details and available documents.

Animals↗
PubMed2000

The premature infant and painful procedures.

Pain management for premature infants raises challenging questions for nurses. This group of infants is often physiologically fragile and they may undergo frequent painful procedures on a daily basis. Contrary to ideas from the past, premature infants are able to feel pain, and nervous system elements required for the transmission of painful stimuli are functional by 24 weeks gestation. Painful procedures are harmful to the infant's physiological stability and the ability to self-regulate, which includes maintenance of motor control and stable sleep/wake cycles. Assessment of pain in the premature infant is complex. Major indicators of pain include facial grimaces and physiological parameters such as heart rate and oxygen saturation. The Premature Infant Pain Profile (PIPP) is one tool designed specifically for preterm infants. Nonpharmacological nursing measures such as swaddling or nesting and offering a pacifier are useful strategies to help infants cope with painful procedures. The nurse may also maintain a therapeutic environment to assist the infant in self-regulation. Pharmacological agents such as morphine, fentanyl, and acetaminophen are effective in relieving procedural pain. The use of oral sucrose before and during painful procedures offers new possibilities for pain relief. Recent research shows that oral sucrose is a safe and effective analgesic for short-term procedures. Research studies to determine the most effective doses and modes of oral sucrose administration are ongoing. It is thought that the relief of pain is owing to the sweet taste of the sucrose that activates endogenous pain-modulating systems.

Analgesics, Opioid↗
PubMed2000

Researching healing: a psychologist's perspective.

This article suggests that a research agenda for healing should encompass qualitative issues of value and meaning as well as quantitative issues of clinical effectiveness. Patients themselves should play an active part in all stages of the research process in order to ensure that the questions addressed are relevant to the needs and wants of those who use healing. Research should address the issues of defining and specifying desired outcomes and clarifying the specific and nonspecific factors in the healing process as well as investigating the potential for harm in treatment and minimizing risk. Some specific research questions are raised. The healing community is challenged to develop a research agenda that is conceptually and methodologically rigorous, true to the holistic nature of complementary and alternative medicine, and retains the subversive edge of the healing traditions.

Humans↗
PubMed2000

Oncology nurses' experience of dimethyl sulfoxide odor.

This article presents findings of an exploratory descriptive study on the effects of dimethyl sulfoxide (DMSO) odor in an oncology unit. The nursing staff, who had reported their concerns about the unpleasant odor emitted from patients undergoing peripheral stem cell transplantation, initiated the study. A literature review revealed some evidence of the possible ill effects on staff caring for patients having DMSO treatment, but many questions remain unanswered such as what staff experience in dealing with DMSO odor and whether nursing care is affected in any way? Data were collected through interviews with 22 oncology nurses who all had experienced direct and indirect exposure to DMSO odor. Of the 22 nurses interviewed, 20 reported that they found DMSO odor unpleasant and reported experiencing physical symptoms such as headaches and gastrointestinal reactions. The study also revealed a situation in which nurses described odor avoidance and distancing strategies that potentially compromised the nurse-patient relationship.

Cryoprotective Agents↗
PubMed2000

A comparison of four quality of life instruments in cardiac patients: SF-36, QLI, QLMI, and SEIQoL.

BACKGROUND: With the increasing use of quality of life measures in evaluations of cardiac interventions, criteria are needed for selecting appropriate quality of life measures. An important criterion is the sensitivity of a measure for detecting clinically important changes. OBJECTIVES: To compare the sensitivity of four measures when used in a group of cardiac patients undergoing the same intervention. METHODS: The short form 36 (SF-36), the quality of life index-cardiac version (QLI), the quality of life after myocardial infarction questionnaire (QLMI), and the schedule for the evaluation of individual quality of life (SEIQoL) were used to evaluate quality of life in a group of 22 patients after myocardial infarction or coronary artery bypass graft (CABG), at the beginning of rehabilitation and six weeks later. Analysable data were obtained from 16 patients. RESULTS: A significant improvement over time was only observed for the SF-36 subscale, vitality (p < 0.05). Five of the eight SF-36 subscales and one of the four QLMI subscales showed modest sensitivity (index: > 0.2 and < 0.5), while all other subscales showed poor sensitivity (index: < 0.2). Using SEIQoL, family was most often nominated as an area of importance to quality of life (n = 13), followed by health (n = 10), leisure/hobbies (n = 8), marriage (n = 8), and work (n = 6). CONCLUSIONS: All four QOL measures used in this study were found to lack sensitivity to change. Further research is needed using other cardiac populations and interventions in order to verify these findings, with a view to developing more sensitive quality of life scales.

Coronary Artery Bypass↗