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Biomedical subjects

M W Johnson

Publications and source records attributed to M W Johnson.

At least 19 recordsLinked to original sources
PubMed2007

Risk of dysplasia and adenocarcinoma following restorative proctocolectomy for ulcerative colitis.

OBJECTIVE: Restorative proctocolectomy (RPC) with or without mucosectomy is the treatment of choice for most patients with ulcerative colitis (UC) requiring surgery. The ileal mucosa in the reservoir and the anorectal columnar epithelium below the ileo-anal anastomosis are at risk of neoplastic transformation. METHOD: The literature has been reviewed to identify patients developing this complication and an attempt has been made to develop a rational follow-up policy based on the data available. RESULTS: Dysplasia in the ileal reservoir is rare. It is associated with histological type C changes, sclerosing cholangitis and unremitting pouchitis in the ileal mucosa and to the presence of sclerosing cholangitis. Nine patients who have developed adenocarcinoma in the residual anorectal mucosa and seven in the reservoir have been reported in the literature. A further hitherto unreported patient treated by the authors brings the total to 17 patients. Twelve of these had histopathological data on either dysplasia or carcinoma in the original operative specimen. The time intervals from the onset of UC and from the RPC to the development of cancer were 120-528 (median 246) and 16-216 (median 60) months respectively. Cancer appeared to be related to the duration of disease rather than to the interval from RPC. In all the reported patients the interval from the onset of UC was 10 years. CONCLUSION: Based on these data a surveillance programme should begin at 10 years from the onset of disease. Patients with dysplasia or carcinoma in the original specimen, those with type C ileal mucosal changes and patients with sclerosing cholangitis should be selected for surveillance. This will involve multiple biopsies of the ileal reservoir and the anorectal mucosa below the ileo-anal anastomosis.

Adenocarcinoma↗
PubMed2003

The behavioral economics of cigarette smoking: The concurrent presence of a substitute and an independent reinforcer.

The present study examined the consumption of cigarettes and two alternative reinforcers in dependent smokers. Cigarette price (response requirement) increased across sessions while alternatives were available at a fixed price in four phases of availability: (1). cigarettes alone; (2). cigarettes and nicotine gum; (3). cigarettes and money; and (4). cigarettes, nicotine gum, and money. Cigarette consumption decreased with increasing price throughout. In the cigarette and nicotine gum phase, nicotine gum consumption increased with cigarette price, indicating nicotine gum to be a substitute for cigarettes. In the cigarette and money phase, money consumption increased slightly with cigarette price, indicating money to be an independent reinforcer for cigarettes. When all three reinforcers were present, money again served as an independent reinforcer. During this phase, nicotine gum consumption increased marginally, but the small magnitude of increase suggests that nicotine gum functioned as an independent reinforcer rather than a substitute. Cigarette consumption decreased modestly when nicotine gum was available, and to a larger extent when money or both alternatives were available. The results highlight the potential for an independent reinforcer such as money to be more effective at reducing drug use than a pharmacological substitute.

Behavior, Addictive↗
PubMed2003

Adolescent chronic illness: a qualitative study of psychosocial adjustment.

INTRODUCTION: The purpose of this study was to investigate the psychosocial issues facing young people living with a chronic medical condition. MATERIALS AND METHODS: Subjects were young people with a range of medical conditions who were on a waiting list to participate in the Chronic Illness Peer Support programme at the Centre for Adolescent Health, Royal Children's Hospital, Melbourne, Australia. Young people agreed to in-depth interviews which were taped and transcribed. Thematic analysis was undertaken by two researchers working independently. RESULTS: Thirty-five young people were interviewed. Thematic analysis revealed five broad themes: control (in control, under control, out of control); emotional reactions (happiness, frustration, anger, sadness, anxiety); acceptance (of illness, of others, of self); coping strategies, and; a search for meaning. The importance of social connections was emphasised. While illustrating the difficulties of managing a chronic medical condition during adolescence, a generally positive message emerges about these young people. CONCLUSIONS: Many young people with chronic illness appear relatively resilient in the face of the adjustment challenges presented by their illness. Interventions that allow a young person to explore meaning, build self-esteem, and acceptance through positive social connections are likely to improve adjustment outcomes in this group.

Adaptation, Psychological↗
PubMed2002

Tacrolimus-induced pain syndrome in a pediatric orthotopic liver transplant patient.

Post-transplant complications are common among patients receiving immunosuppressive medications, including pain syndromes. Recently, a pain syndrome, calcineurin-inhibitor induced pain syndrome (CIPS) has been described. To our knowledge, this article is the second report of tacrolimus-associated CIPS, and the first report in the pediatric setting.

Adolescent↗
PubMed2001

Hamartin expression and interaction with tuberin in tumor cell lines and primary cultures.

Tuberous sclerosis (TSC) is a neurocutaneous disorder characterized by multi-system hamartomatous lesions, and results from a mutation in TSC1, that encodes hamartin, or TSC2, that encodes tuberin. We have examined hamartin expression in a diverse range of human and rat cell lines and primary cultured cells derived from tissues that express hamartin in vivo. Strong hamartin signal was detected in every cell line of human origin examined, representing neuronal, epithelial, lymphoid, renal, vascular smooth muscle, liver, and prostatic cells. Primary cell cultures of oligodendroglioma, meningioma, and glioblastoma multiforme origin were also found to express hamartin. Hamartin was also detected in the rat PC12 cell line, as well as purified primary cultures of rat cortical neurons, astrocytes, and oligodendroglia, with a stronger signal found in astrocytes. Using co-immunoprecipitation, we have also confirmed the physical interaction of tuberin and hamartin in a diverse range of human and rat cell types. These findings demonstrate that hamartin is widely expressed in human and rat cell lines and cultures, and demonstrate that hamartin expression is not lost during the establishment of tumor cell lines or primary cultures. This suggests that the cell lines and cultures studied may serve as useful in vitro models for biochemical investigations involving hamartin and tuberin both individually and as a complex, as well as studies to elucidate the mechanisms underlying the organ-specific pathology of TSC.

Animals↗
PubMed2001

Traumatic macular hole: observations, pathogenesis, and results of vitrectomy surgery.

PURPOSE: To review our experience with vitrectomy surgery techniques for the treatment of traumatic macular holes and the biomicroscopic and surgical findings. DESIGN: Retrospective noncomparative, multicenter, case series. PARTICIPANTS AND INTERVENTION: Twenty-five patients with traumatic macular hole underwent surgical repair. INTERVENTION: Vitrectomy with membrane peeling and gas injection followed by prone positioning for 7 to 14 days. MAIN OUTCOME MEASURES: Postoperative evaluation included visual acuity testing, closure of the macular hole, and ocular complications. RESULTS: The macular hole was successfully closed in 24 of 25 cases (96%). The visual acuity improved two or more lines in 21 (84%) cases, and 16 (64%) achieved 20/50 or better vision. CONCLUSIONS: Vitrectomy surgery can successfully close macular holes associated with trauma and improve vision.

Adolescent↗
PubMed2001

Automated detection of tracé alternant during sleep in healthy full-term neonates using discrete wavelet transform.

OBJECTIVE: To develop an automated procedure for scoring neonatal sleep states using signal processing which are based on visual pattern recognition techniques. METHODS: We are developing an automated computer system to study relationships among multiple non-cerebral physiologic measures and brain activity in newborn infants, and are evaluating the usefulness of a number of different time-frequency domain transforms as potential diagnostic tools. RESULTS: Wavelet transforms yield excellent results in the detection of all twenty tracé alternant quiet sleep segments for 6 full-term healthy infants. CONCLUSIONS: We suggest that this method will be useful for the automated detection of neonatal sleep states, and may help delineate when sleep cycle disturbances occur on either an environmental or disease basis. More accurate physiologic descriptions of neonatal state may improve the clinician's ability to assess functional brain organization for a given post-conceptional age as well as document functional brain maturation at progressively older corrected ages.

Algorithms↗
PubMed2001

Technique of right laparoscopic donor nephrectomy: a single center experience.

The majority of laparoscopic donor nephrectomies (LDNs) are limited to the left side due to technical and allograft concerns in using the right. We review our experience with right LDNs. Since June 1997, 15 right LDNs were performed and the records retrospectively reviewed for demographics, operative time, transfusions, complications, and length of stay. Recipient records were also reviewed for delayed graft function, complications, and serum creatinine levels. Overall donor, recipient and graft survivals at 6 months are 100%. Mean operative time was 317 +/- 11.0 min, length of stay was 4.2 +/- 0.2 d, and mean serum creatinine levels at discharge, 1, 3, and 6 months were 1.74 +/- 0.19, 1.59 +/- 0.13, 1.72 +/- 0.13, and 1.68 +/- 0.13 mg/dL, respectively. No transfusions were required. There were no operative or hospital complications. Two recipients (13.3%) experienced delayed graft function, defined as requiring hemodialysis post-transplantation. With hand-assisted laparoscopy, the right laparoscopic donor nephrectomy is safe and allows excellent allograft function.

Adult↗
PubMed2001

Hamartin and tuberin expression in human tissues.

Tuberous sclerosis (TSC) is a bigenic autosomal dominant disease caused by mutations in one of two tumor-suppressor genes, TSC1 and TSC2, resulting in benign hamartomas and low grade neoplasms in multiple organs including brain, heart, kidney, and skin. We report the results of an immunohistochemical study of the expression of the TSC gene products, tuberin and hamartin, in multiple tissues obtained at autopsy from 12 non-TSC affected patients ranging in age from 20 weeks gestation to 8 years, and surgical specimens from some organs. Tuberin and hamartin are expressed and are colocalized in most tissues. Contrary to a previous report, immunostaining with our antisera detected hamartin in liver, small and large intestine, prostate, and testes. We did not detect significant developmental differences in tuberin or hamartin expression in comparable tissues from patients of different ages. Although tuberin and hamartin colocalize in most tissues and cell types, we provide data that hamartin is more abundantly expressed than tuberin in cells within some tissues including the distal nephron and a population of cells of the endocrine pancreas. These data support the hypothesis that hamartin and tuberin interact and may function together in many tissues where they are co-expressed, but also suggest that hamartin has a discrete and specialized function in certain cell types.

Blotting, Western↗
PubMed2001

Use of transjugular intrahepatic portosystemic shunt as a bridge to liver transplantation in a patient with severe hepatopulmonary syndrome.

Hepatopulmonary syndrome (HPS) is defined by the presence of the triad of liver disease, arterial hypoxemia, and intrapulmonary vascular dilatation. The clinical implication of this disorder is impairment of gas exchange. Numerous reports in the literature show that this condition is reversible with orthotopic liver transplantation (OLT). However, patients with HPS often present with PaO(2) levels that are quite low. OLT with a preoperative PaO(2) less than 50 mm Hg is associated with unacceptably high mortality and morbidity. We report a case of severe HPS in which a transjugular intrahepatic portosystemic shunt was successfully used to improve oxygenation, thus allowing a successful elective OLT.

Female↗
PubMed2001

The living donor experience: donor health assessment and outcomes after living donor liver transplantation.

Despite the increasing use of living donor liver transplantation, little is known about donor needs, concerns, and experiences. The goal of this study is to assess morbidity associated with living donation from a donor perspective, functional status after donation, and overall satisfaction with the donation process. We surveyed all living donors (LDs) from our center. Demographics, perioperative experience, and satisfaction with donation were assessed. The Medical Outcomes Study 12-Item Short-Form Survey (SF-12), a well-validated tool, measured overall health-related quality of life. Of 27 subjects eligible for the study, 27 subjects (100%) participated. Forty percent reported an event they deemed an immediate complication, of which 60% were recorded in the medical record. Complications requiring readmission were reported by 22%. Mean recovery time was 12 weeks (range, 1 to 52 weeks). No significant change was reported in physical activity, social activity, or emotional stability, and 92% of donors resumed their predonation occupation. Regardless of recipient outcome, 100% of donors would donate again and recommend donation to someone in contemplation. All surveyed LDs at our institution are satisfied with their donation decision. Morbidity in the first year after donation may be greater than previously appreciated. Despite complications, postoperative functional status of donors is equal to or better than population norms.

Adult↗
PubMed2001

Perifoveal vitreous detachment is the primary pathogenic event in idiopathic macular hole formation.

OBJECTIVE: To evaluate the relationship between the posterior vitreous cortex and the posterior retina in eyes with early stages of idiopathic macular hole formation. METHODS: Twenty-six eyes of 26 consecutive patients with stage 1 or stage 2 idiopathic macular hole underwent complete ophthalmologic examination, contact lens biomicroscopy, and B-scan ultrasonography or vitreoretinal surgery or both. In eyes that were operated on, the posterior cortical vitreous layer was meticulously examined with a silicone-tipped cannula prior to inducing a posterior vitreous detachment. RESULTS: In 25 (96%) of 26 eyes, one or more examination techniques revealed a shallow, localized detachment of the perifoveal vitreous, typically extending to the level of the vascular arcades. Among these 25 eyes, the posterior hyaloid membrane separation was detectable biomicroscopically in 4 (16%) of 25 eyes, ultrasonographically in 17 (74%) of 23 eyes, and intraoperatively in 23 (100%) of 23 eyes. Persistent vitreous adherence to the foveola was evident in 6 (100%) of 6 eyes with a stage 1 hole and in 12 (92%) of 13 eyes with a stage 2 hole but no operculum. CONCLUSIONS: These findings suggest that localized perifoveal vitreous detachment (an early stage of age-related posterior vitreous detachment) is the primary pathogenic event in idiopathic macular hole formation. We postulate that detachment of the posterior hyaloid from the pericentral retina leads to foveal dehiscence by exerting anterior traction on the foveola and by localizing into the foveola the dynamic vitreous traction associated with ocular rotations.

Aged↗
PubMed2000

Acute knee effusions: a systematic approach to diagnosis.

Knee effusions may be the result of trauma, overuse or systemic disease. An understanding of knee pathoanatomy is an invaluable part of making the correct diagnosis and formulating a treatment plan. Taking a thorough medical history is the key component of the evaluation. The most common traumatic causes of knee effusion are ligamentous, osseous and meniscal injuries, and overuse syndromes. Atraumatic etiologies include arthritis, infection, crystal deposition and tumor. It is essential to compare the affected knee with the unaffected knee. Systematic physical examination of the knee, using specific maneuvers, and the appropriate use of diagnostic imaging studies and arthrocentesis establish the correct diagnosis and treatment.

Acute Disease↗
PubMed2000

Retinal toxicity of commercial intravitreal tissue plasminogen activator solution in cat eyes.

BACKGROUND: We previously reported retinal toxic reactions in rabbit eyes receiving intravitreal injections of commercial tissue plasminogen activator (tPA) in concentrations greater than or equal to 50 microg/0.1 mL, and recent clinical experience suggests that intravitreal tPA solution may produce toxic effects in human eyes. We therefore investigated the dose-dependent retinal toxicity of intravitreal commercial recombinant tPA solution in cat eyes, which have a vascularized inner retina and vitreous volume similar to that of human eyes. METHODS: Commercial tPA in L-arginine solution was injected into the mid vitreous cavity of normal cat eyes in doses of 25, 50, 75, and 100 microg/0.1 mL and 200 microg/0.2 mL. Control (fellow) eyes received an equal volume of sterile saline solution. After injection, eyes were evaluated by ophthalmoscopy and electroretinography for 14 days and then enucleated for histopathological evaluation. RESULTS: Fundus pigmentary alterations were observed in eyes receiving doses greater than or equal to 50 microg/0.1 mL. Changes were centered in the area around the injection site, and the area's size increased in proportion to the dosage. Mean electroretinography B-wave amplitude measured at 14 days was significantly reduced in eyes receiving greater than or equal to 50 microg of tPA in a dose-dependent fashion. Light microscopy of the involved areas showed loss of photoreceptor elements with necrosis and proliferation of the retinal pigment epithelium. CONCLUSION: Intravitreal injection of commercial tPA solution results in dose-dependent retinal toxicity in cat eyes. CLINICAL RELEVANCE: Because cat eyes are similar to human eyes regarding retinal vascularity and vitreous volume, intravitreal injections of commercial tPA (with L-arginine vehicle) in concentrations greater than 25 microg/0.1 mL are potentially unsafe in human eyes.

Animals↗