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Biomedical subjects

D R McLean

Publications and source records attributed to D R McLean.

9 recordsLinked to original sources
PubMed1992

A rare intrapericardial mass in a neonate.

We describe a rare case of a neonate born with an intrapericardial mass composed of extralobar pulmonary sequestration and a cyst of bronchogenic origin. After an uneventful delivery, this full-term newborn was noted to be grunting and indrawing. He remained tachypneic despite adequate management for bilateral pneumothoraces. Diagnostic studies showed a 3 x 3 x 4 cm diameter cystic lesion in the anterior mediastinum causing posterior-lateral displacement of the superior vena cava. The heart itself was structurally normal. Bronchoscopy and esophagoscopy failed to detect any structural abnormalities. At 3 weeks of age, sternotomy and resection of the lesion was performed. The mass was clearly intrapericardial and consisted of sequestrated pulmonary tissue with a unilocular mucus filled bronchogenic cyst. Small systemic tributaries fed the lesion from the posterior-superior aspect. There was no connection with the heart or great vessels. Postoperative recovery was uneventful.

Bronchi↗
PubMed1992

Neurobrucellosis: clinical and therapeutic features.

Eighteen patients with neurobrucellosis are described. Eleven patients had meningitis alone or with papilledema, optic neuropathy, or radiculopathy. Four patients had meningovascular complications manifested by stroke or intracerebral hemorrhage from a presumed mycotic aneurysm. Two patients had parenchymatous dysfunction, including a child who had a cerebellar syndrome without evidence of direct infection of the central nervous system. One patient presented with polyradiculopathy. Twelve of 16 patients had pleocytosis; none had cell counts greater than 419 x 10(6)/L. Most patients had hypoglycorrhachia and elevated levels of protein in the cerebrospinal fluid (CSF). Results of an agglutination test for Brucella in serum were positive for all patients. Six of 16 patients had positive blood cultures, and four of 14 had positive CSF cultures. Antimicrobial treatment included concurrent administration of two or more of the following drugs: streptomycin, tetracycline (or doxycycline), rifampin, and trimethoprim-sulfamethoxazole. Eleven patients fully recovered. Five patients were left with residual neurological deficits. Four of these patients suffered permanent hearing loss, one of whom also had significant loss of vision in one eye. One elderly senile patient with meningovascular brucellosis remained in a vegetative state despite receiving antimicrobial therapy for 6 months. One patient died due to rupture of a mycotic aneurysm within 7 days of initiation of therapy. One other patient was treated after sustaining an intracerebral hemorrhage, but this patient's condition was diagnosed only after discharge.

Adolescent↗
PubMed1992

Bulk diffusion apnea test in the diagnosis of brain death.

OBJECTIVE: To assess the efficacy of bulk diffusion in maintaining oxygenation during apnea testing for brain death. DESIGN: Case series. SETTING: ICU in a primary care hospital. PATIENTS: Twenty-four consecutive patients with suspected brain death. Most patients suffered cerebral trauma from vehicular accidents. INTERVENTION: Patients were preoxygenated with an FIO2 of 1.0 and were maintained during apnea testing with bulk flow of an FIO2 of 1.0 at 40 to 60 L/min in adults and 15 L/min in children. The pre-apnea PaCO2 was between 35 to 45 torr (4.7 to 6.0 kPa) in all patients. MAIN OUTCOME MEASURES: Twenty-three patients completed the test. Five patients had a PaO2 < 100 torr (< 13 kPa) during the 10-min ventilator withdrawal time period. MAIN RESULTS: No patient breathed spontaneously during the apnea test. Twenty-two patients achieved a PaCO2 > 60 torr (> 8 kPa). One patient had a postapnea PaCO2 of 59 torr (7.8 kPa). The test was stopped in one patient who became hypotensive. CONCLUSIONS: The bulk diffusion technique has several advantages, including ease of performance over other methods of supplying oxygen during apnea testing, but this method does not prevent hypoxemia in patients with lung disease.

Adolescent↗
PubMed1990

Treatment of refractory Parkinson's disease with adrenal medullary autografts utilizing two-stage surgery.

Treatment of refractory PD with autologous adrenal medullary implants utilizing two-stage surgery warrants further investigation. This transplantation technique is associated with prolonged transplant area BBB disruption which may require a change in medical treatment strategies including the withdrawal of peripheral dopa decarboxylase inhibitors and possible intravenous or intraventricular dopamine therapy. Of 5 patients receiving adrenal medullary transplants, 3 have demonstrated varying degrees of clinical improvement which has persisted for the duration of the study. The positive correlation between clinical outcome and caudate function (i.e., 6-fluorodopa PET scans) suggests a positive influence of the transplantation procedure on the diseased striatum. Whether or not the grafted tissue remains viable for an extended period is currently being investigated utilizing 6-FDG-PET studies. Because of the presence of persistent BBB disruption, we surmise that at least viability of implanted fenestrated adrenal medullary capillaries exists. We conclude that this prolonged leakage is the result of the implanted tissue rather than the cavitation procedure as prolonged BBB disruption was not witnessed in a control group of patients with post-traumatic cerebral contusions or in Parkinson's patients subjected to thalamotomies. Whether two-stage surgery results in increased graft viability, and host neuronal sprouting, leading to prolonged clinical improvement and slowing the progression of PD awaits continued longitudinal (greater than 24 months) studies.

Adrenal Medulla↗
PubMed1989

Computed radial-current topography of the brain: patterns associated with the normal and abnormal EEG.

We describe a method for producing estimates of radial-current topography underlying the background EEG. This method is based on the application of the laplacian operator to potentials measured on the scalp using a 31-electrode recording array. The laplacian is applied analytically to a potential surface obtained by bicubic-spline interpolation of the measurements at the electrode sites. The results obtained when the method was applied to the alpha rhythm recorded from a normal volunteer and to the slow wave activity recorded from a neurologic patient are presented. The alpha rhythm is associated with areas of strong radial-current activity in the occipital regions (although dominantly right); for the slow rhythm the activity appears in the medial-frontal region. The radial-current topography for the alpha rhythm suggests rotating dipole generators in the occipital lobes whereas it is suggestive of a radially oriented dipole in the case of the delta activity. Discussion is focused upon the apparent advantages of radial-current topography for localizing brain electrical activity, upon the strengths and weaknesses of the method, and upon the observation that the topography of radial current activity obtained would have been difficult to predict from a visual examination of raw EEG traces alone.

Adult↗
PubMed1979

Diphenylhydantoin and pulmonary function.

Thirty-nine epileptic patients underwent pulmonary function testing. Twenty-one of these patients, ranging in age from 16 to 44 years, had taken diphenylhydantoin (DPH) for 2 to 17 years. Eighteen patients, who had taken other anticonvulsants for similar time periods served as controls. Five patients in the DPH group had lung volume abnormalities, four had abnormal airway function, and five had abnormalities of alveolar gas mixing. One patient in the control group had lung volume abnormalities, two had abnormal airway function, and five had abnormalities of alveolar gas mixing. Statistical analysis revealed no significant differences between the groups, or between either group and predicted values.

Adolescent↗
PubMed1978

Multiple sclerosis treated with antithymocyte globulin--a five year follow-up.

Multiple sclerosis patients treated with antithymocyte globulin (ATG) were re-evaluated after five years. No long term benefit was found. Notably, the group of patients with an elevated gamma globulin to total protein ration in their C.S.F. and who did particularly well after treatment with ATG also failed to show any long term benefit. Few long term detrimental effects of ATG immunosuppression were identified. The implications of the results are discussed as they relate to the use of immunosuppression in multiple sclerosis.

Adrenocorticotropic Hormone↗
PubMed1977

A statistical procedure for predicting medical school graduates' specialty choices.

A statistical procedure was devised for selecting, from a group of contenders, a relatively small set of variables which most efficiently predict medical specialty choice. While it is possible to predict medical specialty choice with fair accuracy using subsets of variables, predictions are not conclusive enough to be useful in actual decision-making concerning individuals.

Career Choice↗