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Biomedical subjects

J McNamara

Publications and source records attributed to J McNamara.

At least 55 records · Page 3Linked to original sources

Lymphoma of the mediastinum and neck: evaluation with Ga-67 imaging and CT correlation.

The role of gallium-67 in the differentiation between active disease and fibrotic changes in patients with childhood lymphoma involving the mediastinum and neck was evaluated prospectively. Ga-67 imaging and computed tomography (CT) were correlated with clinical findings at the time of initial presentation and follow-up in 19 patients. Both modalities enabled detection of active disease on all occasions, but CT results were false-positive for residual disease in 10 patients (53%), whereas Ga-67 imaging results were false-positive in only one patient (5%). Neither modality, however, proved accurate in patients with rebound thymic hyperplasia. Ga-67 imaging is a useful tool for assessing response to therapy in children with lymphoma of the mediastinum and neck.

Adolescent↗

Comparison of infrainguinal graft surveillance techniques.

One hundred seventy-seven patients with infrainguinal bypass grafts were followed by use of standard graft surveillance techniques to learn more about the natural history of hemodynamic abnormalities in the patient with no symptoms. A decrease in the ankle/brachial pressure ratio of 10% or more was considered an abnormal evaluation. Results of the duplex scan were interpreted as abnormal when the peak systolic flow velocity was greater than 120 cm/sec or less than 40 cm/sec. There were 18 graft thromboses (10%) during the period of observation, and nine of these grafts were successfully revised or replaced. Recurrent symptoms prompted graft revision in 20 additional patients, and 18 of these reoperations were successful. Twenty-nine of the 38 reoperations occurred within the first 18 months of the study. The primary cumulative patency rate was 86% at 1 year and 66% at 5 years. The secondary cumulative patency rate was 91% at 1 year and 80% at 5 years. Sudden graft occlusion occurred in five patients after a normal ankle/brachial index. Most of 90 patients with abnormal ankle/brachial indexes reverted to normal at the next visit. Nineteen of the 26 that did not, had significant graft problems, but only eight patients had operable conditions, and five of the eight already had occluded grafts. No patient with a normal ankle/brachial index and duplex scan results had graft occlusion before their next surveillance visit. If the duplex scan outcome was abnormal but the ankle/branchial index normal the incidence of sudden graft occlusion was 4%. In contrast, if the duplex scan outcome was abnormal and the ankle/brachial index is reduced, then the risk of graft occlusion is 66%.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Vessel Prosthesis↗

Use of DNA probes to identify Trypanosoma congolense and T. simiae in tsetse flies from The Gambia.

Species- and strain-specific DNA probes were used to identify patent midgut infections in Glossina morsitans submorsitans and G. palpalis gambiensis captured at four sites in The Gambia. 52% of mature Nannomonas infections and 12% of immature infections were identified. Trypanosoma (Nannomonas) simiae accounted for the majority of identified infections in G.m. submorsitans, indicating the importance of distinguishing this species from the closely related T.(N) congolense when assessing the trypanosomiasis challenge to cattle. Both the savannah and riverine-forest groups of T. congolense were present, although the riverine-forest form was found only in G.p. gambiensis at Pirang, an isolated area of forest. Two-thirds of the samples remain unidentified by probes specific for: Trypanozoon; T. congolense savannah, riverine-forest and Kenya coast forms; T. simiae; and T. vivax, probably owing in part to low numbers of trypanosomes. However, the failure to identify several heavy Nannomonas infections, strongly suggests the presence of a further, as yet unknown, kind of Nannomonas.

Animals↗

Elevated soluble interleukin-2 receptor in childhood hemophagocytic histiocytic syndromes.

The serum of children with untreated hemophagocytic syndromes contains elevated levels (23,600 to 75,200 U/mL) of soluble interleukin-2 receptor (SIL2R) that returns toward normal with clinical improvement. These levels are in excess of levels previously reported for benign conditions. They are as high as levels reported for HTLV-1-associated adult T-cell leukemia (HATL) and hairy cell leukemia (HCL) in adults and some children with poor-prognosis non-T, non-B, acute lymphoblastic leukemia (ALL). Serum SIL-2R is a marker of disease activity that has the potential to identify infants at risk for the inherited form of the disease before the disease is clinically expressed.

Adolescent↗

Dental patients in a general pain clinic.

Case histories of 15 patients with dental pain who were examined at the Royal Adelaide Hospital Pain Clinic were reviewed. These were the only patients with dental pain seen at the clinic over a 10-year period and represent less than 1% of the total patients fully examined at the clinic. Only one patient had an underlying organic problem; the remainder had a diagnosis of atypical facial pain. Common characteristics that pointed to the diagnosis of intractability were the duration of the pain, extensive and multiple ineffective treatments, a history of pain elsewhere in the body, and a history of psychologic disturbance. Ten of the 12 patients who were offered and accepted psychotherapeutic treatment had appreciable symptomatic relief. No dental or surgical treatments resulted in any pain relief.

Adult↗

The effects of pentoxifylline on patients with intermittent claudication.

All patients who had intermittent claudication (IC) over an 18-month period were given prescriptions for pentoxifylline (PTFX) 400 mg, three times daily. Patients were required to purchase their medication at a cost of $28 to $35 per month. The drug was administered regardless of the severity of symptoms, and no patient was offered operation without at least a 6-week trial of PTFX. An assessment of the severity of IC was made at the initial visit based on noninvasive data and the impact of the IC on the patient's life-style. One hundred thirty patients were enrolled in the study and were followed for 9 +/- 1 months. Patients were seen every 2 months for treadmill exercise or induced hyperemic testing and interviews until the effects of the medication were determined. The duration of IC before the start of treatment had no effect on the results. IC did not improve in 88 patients (71%) followed for 7.2 +/- 1 month. Thirty-six of these patients stopped the drug themselves because there was no benefit and the expense of PTFX was a hardship. An initial but short-lived improvement in walking was noted in another 13 patients (10%) following 14 +/- 2 months, and the medication was eventually discontinued. Only 23 patients (19%) followed for 11.6 +/- 2 months felt that IC had improved to the point where they did not feel limited in any way. Gastrointestinal symptoms occurred in 13 patients and were severe in eight patients (6%) who stopped taking the medication. The results of PTFX in this group of patients with IC were disappointing at best.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug Evaluation↗

MRI CT, and plain film appearance of anterior spina bifida.

Anterior spina bifida or butterfly vertebral body has a well known and characteristic appearance on plain film and CT. Its appearance on magnetic resonance imaging also appears to be characteristic and should not be mistaken for more serious abnormalities.

Humans↗

Abnormalities in the immune system of children with beta-thalassaemia major.

We have studied both the humoral and cell mediated immune systems of 23 children with beta-thalassaemia major. In children who had not been splenectomized, a 3-fold expansion in the number of circulating B cells and a modest polyclonal gammopathy was present. Of these patients 70% had decreased numbers of circulating T4 cells; 83% were unresponsive to skin testing with Candida albicans, and the majority had decreased lymphocyte proliferative responses in vitro. In children who had been splenectomized, there was a 10-fold increase in the number of circulating B lymphocytes and a 2-fold increase in the number of T4 and T8 cells present in peripheral blood. Additionally, these patients as a group were more responsive to both skin testing and lymphocyte stimulation in vitro with Candida albicans. Seven patients had an inverted T4/T8 ratio. One child has positive serology to HIV by ELISA and Western Blot techniques with a normal T4/T8 ratio. Thus, while children with thalassaemia are at risk for exposure to HIV, the immunological abnormalities associated with the disease and/or its treatment necessitates cautious interpretation of any AIDS-related immunological changes.

Acquired Immunodeficiency Syndrome↗

Optimal resources for carotid endarterectomy.

This review compares the results and costs of carotid endarterectomy (CE) done by a single surgeon over a 1-year period working at both a university hospital (UH) and a community hospital (CH). Hospital and financial records of 157 patients were reviewed, 78 at UH and 79 at CH. The patient populations were matched for age, associated illnesses, and presenting symptoms. The principles of patient management were identical at both hospitals except that shunting requirements were determined by electroencephalographic monitoring at UH. There were no differences in the complication rates, and the combined stroke/mortality rate was 0.6%. The cost of CE was 56% greater on a per patient basis at UH ($3918 versus $6126, p less than 0.001) and 23% greater on a per diem basis at UH ($611 versus $755, p less than 0.001). Patients stayed longer at UH (8.2 days versus 6.6 days at CH, p less than 0.03). These differences are largely explained by three types of delays at UH. First, patients with cardiovascular accidents at UH were kept in the hospital before surgery until maximum improvement occurred whereas patients at CH were allowed to convalesce at home before CE. Patients operated on after a cardiovascular accident spent an average of 17.6 days in UH while a similar group spent only 7.3 days in hospital at CH (p less than 0.03). Second, delays in obtaining angiograms of greater than 2 hospital days occurred in 28% of patients at UH compared with only 10% at CH (p less than 0.05). Third, delays in scheduling operating room time of greater than 2 hospital days occurred in 17% of patients at UH and in only 7% of patients at CH (p less than 0.05). When there were no delays, the cost of treating patients at each hospital was identical, $3483 at CH and $3520 at UH. UH must accept the fact that equally good results can be obtained at CH, and although the potential exists for equal costs at both types of hospitals, the CH provides the service at a lower cost. UH administrators must address these inefficiences if the UH is to compete effectively in the current marketplace.

Aged↗

Transplantation of thymic tissue into patients with AIDS. An attempt to reconstitute the immune system.

Thymic epithelial fragments were transplanted into 15 patients in an advanced stage of the acquired immunodeficiency syndrome (AIDS). One patient was given interleukin 2 in addition to thymic tissue. We demonstrated the following: Thymic epithelial fragments cultured before transplantation to remove T cells survived for months after transplantation in eight of 15 patients and seemed to be responsible for a partial, selective, but transient repopulation of the circulating T-cell pool. The absolute number of T8 cells, but not T4 cells, increased three to four weeks after the procedure in eight of the 15 subjects. This increase in T8 cells was associated with clinical improvement in some cases and increased T-cell responsiveness in vitro. Thymic tissue transplantation as a single therapeutic maneuver is unlikely to reconstitute the immune system of patients with AIDS, but the potential of the approach, used in combination with agents that block replication of human T-cell lymphotropic virus type III, deserves further study.

Acquired Immunodeficiency Syndrome↗

How to maximize reward rate on two variable-interval paradigms.

Without assuming any constraints on behavior, we derive the policy that maximizes overall reward rate on two variable-interval paradigms. The first paradigm is concurrent variable time-variable time with changeover delay. It is shown that for nearly all parameter values, a switch to the schedule with the longer interval should be followed immediately by a switch back to the schedule with the shorter interval. The matching law does not hold at the optimum and does not uniquely specify the obtained reward rate. The second paradigm is discrete trial concurrent variable interval-variable interval. For given schedule parameters, the optimal policy involves a cycle of a fixed number of choices of the schedule with the shorter interval followed by one choice of the schedule with the longer interval. Molecular maximization sometimes results in optimal behavior.

Journal Article↗

Monitoring ambulatory care: impact of a surveillance program on clinical practice patterns in New York City.

Administrative records of the Title XIX (Medicaid) Program of New York City were reviewed to determine the impact of a surveillance system introduced to monitor physician billing. Billing patterns of the physicians subject to program sanctions, as well as the larger universe of all participating New York City physicians, showed changes coincident with the introduction of the surveillance program: utilization of x-rays, lab tests, injections, and first visit billing decreased.

Ambulatory Care↗