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Biomedical subjects

N Mitchell

Publications and source records attributed to N Mitchell.

At least 19 recordsLinked to original sources
PubMed2006

Centralization of services: standard setting and outcomes.

OBJECTIVE: To test specific standards set in the newly established cleft lip and palate service in three regions of the U.K. The standards relate to record collection and outcomes. DESIGN: Retrospective analysis. PATIENTS: Records of 31 children, 5 years of age, who were born in 1997 with complete unilateral clefts of lip and palate and were treated by surgeons in three regions. MAIN OUTCOME MEASURES: Record collection standards were measured by collecting dental study models. Outcomes were measured with the 5-Year-Old Index. RESULTS: Of the 31 subjects, 52% had excellent and good outcomes. The 31 cases represented 62% of the total records collected. CONCLUSIONS: The three regions examined fell short of the standards set, but the outcomes were improved compared with previous national outcomes. The failings in record collection need to be rectified. This study provides baseline data for further development of cleft services within three regions.

Child, Preschool↗
PubMed2004

Factors influencing concordance with compression stockings after venous leg ulcer healing.

OBJECTIVE: To investigate the factors influencing patient concordance with compression stockings after venous leg ulcer healing. METHOD: In 2001 patients discharged from a specialist leg ulcer service in New Zealand were approached to participate in a structured interview about their use of compression stockings in the first six months following venous leg ulcer healing. Univariate analyses were performed to identify significant associations between factors and stocking use. Multiple logistic regression was employed to model the factors associated with frequency of stocking use. RESULTS: A total of 163 patients were identified, of whom 129 (79%) agreed to participate. Sixty-seven (52%) reported wearing stockings every day for the first six months after their ulcers had healed, 21 (16%) stated that they had worn the most days, seven (5%) had worn them occasionally and 29 (22%) had not worn them at all after their ulcer had healed. Five (4%) did not provide data. Two factors distinguished those who wore stockings from those who did not 75% of the time: the belief that wearing stockings was worthwhile and the belief that stockings were uncomfortable to wear. Commonly cited factors, such as age, sex, difficulty in applying stockings and cosmetic appearance were not significantly related to stocking use. Cost did not seem to influence the decision to purchase compression stockings. CONCLUSION: Many factors previously thought to influence concordance appear to have little impact on compression-stocking use in people whose venous leg ulcers had healed.

Aged↗
PubMed2003

Choice of cross size in stereology--a cautionary note.

The stereological method of cross-counting based on the Cavalieri principle is widely used in neuroimaging to estimate the volume of cerebral structures. Although superficially simple, the stereological technique is validated by arcane mathematical proofs, so the cross size is determined by most investigators on a pragmatic basis with the assumption that the volume calculated is independent of the cross size used. We used three cross sizes (8x8, 5x5 and 3x3 voxels) to estimate the brain volume of six healthy control subjects. The volume estimate using a cross size of 3x3 was 9% larger than with a cross size of 5x5 and the latter was 15% larger than with a cross size of 8x8. We conclude that cross size significantly affects whole brain volume estimates and this result is presumably applicable to other structures whose cross-sectional areas form complex shapes. Investigators should be aware of this fact, especially when trying to make direct comparisons between volume estimates derived from the stereological method using different cross sizes.

Adolescent↗
PubMed1998

Older medical students' performances at McGill University.

PURPOSE: To compare admission data and academic performances of medical students younger and older than 25, and to qualify older students' experiences and perceptions in medical school. METHOD: The authors reviewed 1988-1991 data for applications to the McGill University Faculty of Medicine. Data included GPAs and MCAT scores, as well as ratings for reference letters, autobiographical statements, and interviews. For those same years, the authors measured students' academic performances in the preclinical and clinical years. The authors compared the data by students' age: "younger" students, aged 17 to 24; and "older" students, aged 25 and above. All enrolled students took the Derogatis Stress Profile, and the older students participated in focus groups. RESULTS: The older applicants had lower GPAs and MCAT scores, but higher interview and reference letter ratings. For older accepted students, basic science course scores were lower than those of younger students, but clinical scores did not differ significantly between the groups. The two groups had similar stress levels, although older students tested lower in driven behavior, relaxation potential, attitude posture, and hostility. In focus groups, the older students spoke of learning style differences, loss of social support, and loss of professional identity. CONCLUSION: Different scores in admission criteria suggest that McGill uses different standards to select older medical students. Older students admitted under different criteria, however, do just as well as do younger students by their clinical years. A broad-based study of admission criteria and outcomes for the older student population is warranted.

Adolescent↗
PubMed1997

In-vivo degradation of polyurethanes: transmission-FTIR microscopic characterization of polyurethanes sectioned by cryomicrotomy.

A combination of cryomicrotomy and transmission Fourier transform infrared (FTIR) microscopy was used to investigate chemical changes in unstrained sheets of Pellethane 2363-80A, Tecoflex EG80A and Biomer caused by biodegradation (18 month subcutaneous ovine implant). Cryomicrotomy was used to obtain thin sections (ca. 2.5 microm) from the surface into the bulk, parallel to the plane of the surface. FTIR microscopy was then used to obtain infrared absorbance spectra in the range 4000-600 cm(-1). Comparisons between the infrared spectra (by spectral subtraction) from implant surface, implant interior and non-implanted controls were used to detect chemical changes. Scanning electron microscopy was used to assess microstructural changes owing to biodegradation. Biodegradation in Biomer was observed as uniform pitting and superficial fissuring (<2.0 microm depth) over the implant surface. Biodegradation in Pellethane 2363-80A and Tecoflex EG 80A was observed as severe localized embrittlement of the surface with fissures infiltrating up to 40 microm into the bulk. The chemical changes associated with biodegradation were observed as localized oxidation of the soft segment and hydrolysis of the urethane bonds joining hard and soft segments. Tecoflex EG80A was also found to be susceptible to localized hydrolysis of the urethane bond within the aliphatic hard segment. Biomer showed evidence of a significant non-specific degradation in the non-implanted wet control (37 degrees C phosphate buffered saline at pH 7.3) samples and in the implant bulk.

Animals↗
PubMed1996

On the role of aging in carcinogenesis.

Correlation coefficients for age-standardized incidence rates between cancers of the stomach, colon, rectum and lung over place (worldwide) and time (in Connecticut) vary from positive to negative values, indicating that these cancers are not caused by common environmental agents. Correlation coefficients for age-incidence patterns (the variation in age-specific rates with age) between these cancers, on the other hand, are all highly positive for both sexes. We conclude that the carcinogenic determinants that vary with age are common to the cancers studied and to both sexes, and distinct from the carcinogenic determinants that vary with place and time. For the cancers studied, incidence rates are negligible until age 30, at which time they increase dramatically and continue to increase at least until age 75. The rate of increase, however, diminishes continuously with advancing age after 30. We suggest that the role of aging in cancer incidence is determined by two components, one responsible for the dramatic rate increase beginning near age 30 and one responsible for the gradual diminution in that rate increase. The former may correspond to the activation of quiescent cells with damaged DNA or to the deactivation of DNA surveillance or repair or to impaired apoptosis, while the latter may correspond to the loss of cell division potential.

Adult↗
PubMed1996

Gorham's disease of the spine.

Massive osteolysis is a rare condition and is very uncommon in the spine. The MRI appearance of Gorham's disease of the spine has not previously been reported. We present here a case of this condition with imaging details.

Child, Preschool↗
PubMed1996

Juvenile chronic arthritis of the hip: value of contrast-enhanced MR imaging.

OBJECTIVE: The purpose of this study was to assess the value of contrast-enhancement in MR diagnosis of hip joint disease in patients with juvenile chronic arthritis. PATIENTS AND METHODS: Fourteen hips in seven children (four girls, three boys; mean age, 11 years; range, 7-17 years) with juvenile chronic arthritis for a mean duration of seven years (range, 3-15 years) were imaged on a 0.5T MR unit. One patient had an MR scan repeated after an 8-month interval. Axial and coronal T1-weighted spin-echo, and axial gradient-echo sequences were performed. T1 weighted axial sequences were repeated immediately after 0.1 mmol/kg of intravenous gadopentetate dimeglumine. Patients were assessed clinically for pain in the hip, range of motion at the hip joint, haemoglobin and erythrocyte sedimentation rate. Two radiologists, unaware of the patients symptoms, jointly assessed the unenhanced and contrast-enhanced scans for synovial hypertrophy (pannus), cartilage destruction and joint effusion. RESULTS: Pannus was underestimated on 75% of unenhanced MR scans (95% binomial confidence intervals 54% to 93%). Enhancing pannus was seen in 14 of the 16 hip MR scans. Enhancing pannus was associated with articular cartilage destruction in all cases, and joint pain in 13 of 14 scans. Joint effusions were overestimated on unenhanced scans in all cases. Pannus could only reliably be distinguished from joint effusion after contrast enhancement. Both cases of loculated joint effusion were only seen after contrast enhancement. CONCLUSION: Contrast-enhancement is recommended to aid MR detection of disease activity and extent in children with juvenile chronic arthritis of the hip.

Adolescent↗
PubMed1995

Case report: effect of pregnancy on idiopathic juvenile osteoporosis.

Adolescence and pregnancy are periods with increased calcium requirement. Therefore, patients with underlying bone disease are at risk for further bone demineralization during these periods. In this article, the authors report on the treatment during pregnancy of an adolescent with idiopathic juvenile osteoporosis that resulted in a favorable outcome of maternal and fetal skeleton.

Adolescent↗
PubMed1994

Evaluations of children who have disclosed sexual abuse via facilitated communication.

OBJECTIVE: To review the findings of interdisciplinary team evaluations of children who disclosed sexual abuse via facilitated communication. DESIGN: Case series. SETTING: Tertiary care hospital outpatient child sexual abuse program in central New York. PATIENTS: Between January 1990 and March 1993, 13 children who disclosed sexual abuse via facilitated communication and were referred to a university hospital child abuse referral and evaluation center. The range of previously determined developmental diagnosis included mental retardation, speech delay, and autism. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Medical records were reviewed for (1) disclosure, (2) physical evidence, (3) child's behavioral and medical history, (4) disclosures by siblings, (5) perpetrator's confession, (6) child protective services determinations, and (7) court findings. RESULTS: Four children had evidence of sexual abuse: two had physical findings consistent with sexual abuse, one also disclosed the allegation verbally, and one perpetrator confessed. CONCLUSIONS: These results neither support nor refute validation of facilitated communication. However, many children had other evidence of sexual abuse, suggesting that each child's case should be evaluated without bias.

Adolescent↗
PubMed1992

Multiple phantom limbs in a child.

This case report describes multiple phantom feet in a child after amputation of a leg. The subject is a 16-year-old girl who was born with a right leg 10 cm shorter than the left and who at the age of 6 was amputated below the right knee so that she could wear a prosthesis that would give her normal mobility. The girl reports that she subsequently experienced 2 phantom feet and 3 sets of phantom toes which have persisted to the present time. Each phantom has a distinct size, length and position in relation to the others and each is also the site of vivid sensations such as heat, tickle, and fatigue as well as voluntary and involuntary movement. She also describes sensations that resemble sensations experienced before the amputation: one of her phantom feet feels flat and locked into a forward position which corresponds with the actual shape and position of her congenitally deformed amputated foot. The implications of multiple phantoms are discussed with reference to recent concepts of phantom limbs.

Adolescent↗
PubMed1992

The clones of osteoarthritic cartilage.

We studied the early cartilage changes in osteoarthritis, examining the most normal appearing articular cartilage from the hips of 17 patients. Normal appearing cartilage from five patients treated for fractures was used as control material. Two different types of clone were found. The first had increased staining for proteoglycan and was thought to have been engaged in the synthesis of matrix. The other type was associated with a severe deficiency of proteoglycan, matrix streaks and evidence of degradation and phagocytosis of matrix components. Immunohistochemistry demonstrated large amounts of chondroitin 4 and 6 sulphate about the synthetic-type clones, and little or no reactivity about the degenerative clones which lay more superficially and were associated with matrix destruction. Clones appeared to be engaged in either matrix synthesis or its destruction. The disease process of osteoarthritis appeared to begin at the surface of the articular cartilage.

Aged↗
PubMed1990

Permanent external striated sphincter stents in patients with spinal injuries.

Nine patients with complete quadriplegia underwent external striated sphincter stenting with the Wallstent in place of an external striated sphincterotomy. Although suprapubic catheters were placed to provide an outlet should problems develop with the stent, they were successfully removed within 6 weeks in all but 1 patient. Complete bladder emptying with reduced voiding pressures was achieved, together with a significant reduction in the duration of hyper-reflexic contractions. Epithelialisation of the stent was almost complete within 3 months and intermittent catheterisation or endoscopy (and resection) is possible through the stent. Although this is a preliminary report of this new technique, it is hoped that sphincter stenting will provide a rapid, safe and effective method of treating high pressure hyper-reflexia and detrusor sphincter dyssynergia in quadriplegic patients.

Adult↗
PubMed1990

Routine admission urinalysis examination in pediatric patients: a poor value.

The urinalysis has long been considered an important screening test for hospitalized children. The value of the admission urinalyses, required by hospital bylaws, was assessed for detecting urinary tract disease in children admitted to a day-care unit or impatient medical or surgical services during the months of June and November 1987. Of 2695 admissions, urinalyses were considered essential for diagnosis or therapy in 543 patients (excluded from analysis). In the remaining 2152 patients eligible for screening, urinalyses were obtained in 145 (30%) of day-care unit and 587 (35%) of inpatient admissions. The results of 149 (20%) of screening urinalyses were abnormal (23% abnormal in inpatient and 10% abnormal in day-care unit admissions). The numbers of urinalyses with abnormal results were similar in surgical and medical admissions and between the months of June and November. Pyuria (90 patients) and hematuria (66 patients) were the most common abnormalities in initial urinalyses. Follow-up urinalyses and other diagnostic studies were obtained in 38% of patients with abnormal admission urinalysis results. In subsequent urinalyses, 58% showed persistent abnormalities; however, most subsequent abnormal results were not pursued with additional tests. Urinary tract infections were diagnosed in 6 patients. No other additional diagnoses were determined. The cost of initial urinalyses and subsequent diagnostic studies in these 732 patients during the 2 months was $23,465. The cost per diagnosis of urinary infection was $3911. It is concluded that when hospital bylaws require routine urinalyses at the time of admission, this requirement is frequently ignored and, in addition, abnormal results are often unappreciated or not pursued.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1989

Improved chondrocyte morphology and glycogen retention in the secondary center of ossification following osmium-potassium ferrocyanide fixation.

The use of osmium-potassium ferrocyanide as the secondary fixative greatly improved chondrocyte preservation and stabilized the cartilage matrix proteoglycan. The proteoglycan was similar in appearance to that seen following fixation in the presence of cationic dyes. Extensive glycogen preservation was noted in these cells, occupying the area prior to and during the formation of the secondary center of ossification. The volume and organization of the glycogen within the cell cytoplasm were greater than that following buffered osmium fixation, and the cellular vacuoles within were greatly reduced. The cells forming the secondary center prior to the onset of mineralization were of greatest interest, because other studies compared them with the primary growth plate and described them as showing signs of hypertrophy as early as 5 days postnatally, as is found in the primary growth plate. Our observations indicate that glycogen is present in these cells, and cellular enlargement was not present. The cells do not resemble the hypertrophic chondrocytes of the primary growth plate, as far as cytoplasmic content is concerned, and we suggest that they may contribute to the development of the secondary center in a different fashion.

Animals↗