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Biomedical subjects

B M O'Connell

Publications and source records attributed to B M O'Connell.

15 recordsLinked to original sources
PubMed2000

Numerical model of deep venous thrombosis detection using venous occlusion strain gauge plethysmography.

Strain gauge plethysmography (SGP) is a non-invasive method used in the detection of deep venous thrombosis (DVT). The technique is based on the measurement of calf volume changes in response to venous occlusion by a thigh cuff, the volume changes reflecting the rates of arterial inflow and venous outflow. A numerical model of the blood circulation within the limb and the response of this to a SGP test has been derived, based on treating the different parts of the circulatory system in the leg as resistance and capacitance elements. The simulation results were compared with clinical studies and support the ability of SGP to detect non-occlusive clots of more than 50-60% of the lumen, as well detecting calf vein occlusion. The non-linear behaviour of the venous compliance with intra-luminal pressure appears to be a particularly important factor within the model. In addition, increases in venous tone due to post-operative venospasm were shown to be a potential source of false positive results.

Humans↗
PubMed1994

Crown architecture of understory and open-grown white pine (Pinus strobus L.) saplings.

Crown architecture and growth allocation were studied in saplings of eastern white pine (Pinus strobus L.), a species classified as intermediate in shade tolerance. A comparison was made of 15 understory saplings and 15 open-grown saplings that were selected to have comparable heights (mean of 211 cm, range of 180-250 cm). Mean ages of understory and open-grown trees were 25 and 8 years, respectively. Understory trees had a lower degree of apical control, shorter crown length, and more horizontal branch angle, resulting in a broader crown shape than that of open-grown trees. Total leaf area was greater in open-grown saplings than in understory saplings, but the ratio of whole-crown silhouette (projected) leaf area to total leaf area was significantly greater in understory pine (0.154) than in open-grown pine (0.128), indicating that the crown and shoot structure of understory trees exposed a greater percentage of leaf area to direct overhead light. Current-year production of understory white pine was significantly less than that of open-grown white pine, but a higher percentage of current-year production was allocated to foliage in shoots of understory saplings. These modifications in crown structure and allocation between open-grown and understory white pine saplings are similar to those reported for more shade-tolerant fir (Abies) and spruce (Picea) species, but the modifications were generally smaller in white pine. As a result, white pine did not develop the flat-topped "umbrella" crown structure observed in understory fir and spruce, which approaches the idealized monolayer form that maximizes light interception. The overall change to a broader crown shape in understory white pine was qualitatively similar, but much more limited than the changes that occurred in fir and spruce. This may prevent white pine from persisting in understory shade as long as fir and spruce saplings.

Journal Article↗
PubMed1994

Postphlebitic syndrome after hip arthroplasty. 43 patients followed at least 5 years.

We reviewed 43 patients using clinical scoring for evidence of postphlebitic syndrome at least 5 years after hip replacement. All had had a venogram as part of a screening study at the time of surgery. The postphlebitic syndrome was identified in 13 patients and was disabling in 6. The syndrome was present in 9 of the 11 patients with a venographically proven deep vein thrombosis (DVT) and in 4 of the 32 without DVT. Postphlebitic sequelae had developed despite anticoagulant therapy for the acute DVT. The postphlebitic syndrome following asymptomatic deep vein thrombosis is an important long-term complication of total hip replacement.

Anticoagulants↗
PubMed1987

Solitary labial papular acantholytic dyskeratoma in an immunocompromised host.

A 42-year-old white man presented with a solitary labial papule 4 years after cardiopulmonary transplantation. Pathological examination of the excised papule revealed a tumor with prominent acantholytic dyskeratosis. Risk factors for skin tumors in this patient included habitual tobacco chewing, chronic unprotected solar exposure, and an immunosuppressive regimen comprising prednisone and cyclosporin-A. This is the first report of an acantholytic dyskeratoma in association with these predisposing conditions.

Acantholysis↗
PubMed1987

Familial Prader-Willi syndrome.

Three adult sisters with previously unrecognized Prader-Willi syndrome (PWS) demonstrated the six diagnostic features of this congenital condition: neonatal hypotonia, hypomentia, hypogonadism, obesity, short stature, and dysmorphism. Detailed endocrine investigations were performed, including ovarian biopsy in the propositus. HLA genotype A2 was present in each patient. The normal high-resolution prometaphase karyotypes indicated heterogeneity; the absence of the deletion 15q12 frequently found in patients with sporadic PWS distinguished this sibship as representing a possible autosomal recessive type of PWS. Current evidence suggests that the diagnosis of PWS may be often overlooked. Increased clinical awareness of the features of PWS should result in prompt diagnosis and optimal management of affected patients, together with increased understanding of this enigmatic condition.

Adult↗
PubMed1986

Tinea in tiny tots.

Dermatophyte infections in infants and toddlers, with the exception of tinea capitis, are considered rare. We describe representative patients to illustrate the broad clinical spectrum of these infections in this age group. We review possible pathophysiologic mechanisms, diagnostic modalities, and therapeutic regimens. Our experience suggests that involvement of areas other than the scalp may be more common than current estimates suggest. Recognition of affected patients is important in view of the wide differential diagnosis and the efficacy of current treatment.

Antifungal Agents↗
PubMedDate not supplied

Dermatologic complications following heart transplantation.

A total of 107 consecutive heart transplant recipients at Stanford University Medical Center were prospectively screened for dermatologic disease as part of their routine postoperative evaluation over a 6-month period. The incidence of nonmelanotic skin tumors and premalignant lesions was approximately 25-fold greater than expected in a normal population. Skin infections were seen in 55% of the patients and dermatologic drug side effects were almost universal including xerosis, hypertrichosis, and steroid acne. Successful excision or cryotherapy of all neoplastic lesions was achieved with no evidence of recurrence to date, a mean of 11 months. The skin infections responded to appropriate antiviral, antibacterial, and antifungal agents and the xerotic and acneiform lesions were successfully treated with emollients and topical retinoic acid, respectively. In addition, patients were instructed in preventive measures including the use of sunscreen agents and protective clothing. We conclude that heart transplant recipients have a significantly increased incidence of neoplastic, infectious, and drug-induced skin diseases. Routine dermatologic screening resulted in early identification and successful treatment of these lesions. We suggest that dermatologic screening is both feasible and valuable in this setting.

Adult↗
PubMedDate not supplied

The spectrum of cytomegalovirus infection following human heart-lung transplantation.

Data were analyzed from 19 long-term survivors of cardiopulmonary transplantation in this institution, including nine patients with normal pulmonary function and 10 recipients with posttransplant obliterative bronchiolitis. In all cases, donor cytomegalovirus titers (IgG), preoperative recipient titers (IgG), and serial postoperative recipient titers (IgM, IgG, and complement fixation) were available. In addition, surveillance cytomegalovirus cultures and pulmonary function tests were obtained prospectively after surgery in all 19 patients. A total of 12 patients developed active cytomegalovirus infection (serologic conversion confirmed by positive cultures) after transplantation, six of whom subsequently developed obliterative bronchiolitis. However, infection was clinically associated with pulmonary deterioration in only four of these patients, three of whom had cytomegalovirus pneumonitis. With the exception of obliterative bronchiolitis, no other permanent sequelae of cytomegalovirus infection were evident in this small group. Progressive obliterative bronchiolitis was also seen in four of the seven recipients who had no evidence of cytomegalovirus infection at any time. Although viral causes have been associated with obliterative bronchiolitis, the current data suggest that cytomegalovirus infection in the absence of pneumonitis does not appear to be a significant risk factor for obliterative bronchiolitis in cardiopulmonary transplant recipients. A larger group of patients will be required to ultimately establish the role of cytomegalovirus infection in this setting.

Antibodies, Viral↗