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Biomedical subjects

J R Little

Publications and source records attributed to J R Little.

At least 91 records · Page 5Linked to original sources
PubMed1984

Induction of amphotericin B-specific antibodies for use in immunoassays.

High-titered antisera specific for amphotericin B (AmB) were induced by immunization with a protein conjugate of the D-lysyl AmB methyl ester. These polyclonal anti-AmB antibodies reacted preferentially with AmB or the AmB methyl ester and discriminated sharply between nystatin and AmB. A solid-phase radioimmunoassay was developed with radioiodinated immunoglobulin G fractions derived from the anti-AmB antisera. This assay was capable of detecting AmB in the sera in the same concentration range that is regularly achieved during AmB treatment of systemic fungal infections. This study demonstrated the feasibility of immunoassays in measuring the concentration of AmB in blood and tissue fluids.

Amphotericin B↗
PubMed1984

Changes in intracranial stenotic lesions after extracranial-intracranial bypass surgery.

The natural history of intracranial arterial stenosis is not well understood. The lesions are pathologically quite diverse, and are subject to resolution, progression, or occlusion. The authors undertook an investigation to examine what effects, if any, extracranial-intracranial (EC-IC) bypass surgery had on the evolution of intracranial arterial stenosis in 18 patients undergoing EC-IC bypass procedures for ipsilateral hemispheric ischemia. There was inaccessible internal carotid artery stenosis in 14 patients, and middle cerebral artery stenosis in four patients. Early (within 2 weeks) and late (at 6 months) postoperative angiography was performed in all patients. During the period of the study, there was a significant change in the arterial stenosis in 50% of the patients (nine of 18). The stenotic artery became occluded in four patients while the grafts were widely patent. The occlusion occurred within a few days after the operation in three of the four cases, and was accompanied by an ischemic stroke in these patients. There was improvement or resolution of the stenotic lesion in five patients; the graft became occluded in two of these cases and was patent but showed poor cortical artery filling in the other three. All these patients remained asymptomatic and the change was detected on routine late postoperative angiograms. It is concluded that arterial stenoses should not be viewed as static or inflexible lesions, and that EC-IC bypass procedures can modify the hemodynamic parameters across stenotic lesions, predisposing them to improvement or worsening. This, in turn, may affect bypass patency. Such hemodynamic interactions are accompanied by ischemic symptoms in some patients, and contribute to the relatively higher morbidity associated with EC-IC bypass surgery in the setting of arterial stenosis.

Adult↗
PubMed1984

Saphenous vein patch grafts in carotid endarterectomy.

The clinical data and findings on the early postoperative intravenous digital subtraction angiograms (IVDSA's) were studied in 61 patients undergoing 70 consecutive conventional carotid endarterectomies and in 46 patients undergoing 50 consecutive carotid endarterectomies with a saphenous vein patch graft (SVPG). The IVDSA's were considered normal in 50 of 70 conventional carotid endarterectomies and in 46 of 50 carotid endarterectomies with SVPG (p = 0.004). The internal carotid artery (ICA) origin was consistently larger and had a more normal configuration after carotid endarterectomy with SVPG. Ballooning at the endarterectomy site was an uncommon finding and occurred with similar frequency in both groups; that is, after three conventional carotid endarterectomies and two carotid endarterectomies with SVPG. In the conventional group, early symptomatic thrombosis occurred in the ICA in one patient and in the common carotid artery (CCA), ICA, and external carotid artery (ECA) in two patients. Silent ICA occlusion was seen in three patients in the conventional group. There were no occlusions in the SVPG group (p = 0.04). Stenosis at the distal end of the ICA arteriotomy was found after nine conventional carotid endarterectomies, and was mild (less than or equal to 33% reduction in the lumen) in seven patients, moderate (34% to 66%) in one, and severe (greater than or equal to 67%) in one. Mild distal ICA stenosis was seen in one case after carotid endarterectomy with a SVPG (p = 0.03). Stenosis of 33% or less was found at the proximal end of the CCA arteriotomy after two carotid endarterectomies in the conventional group and one carotid endarterectomy in the SVPG group. Four patients in the conventional group suffered a postoperative cerebral infarct and one patient in the SVPG group suffered a postoperative brain-stem infarct (p = 0.28). The authors' findings have led them to routinely use a SVPG in carotid endarterectomy.

Aged↗
PubMed1984

Thromboxane synthetase inhibition in acute focal cerebral ischemia in cats.

The purpose of this investigation was to study the effects of a selective thromboxane A2 (TXA2) synthetase inhibitor (TSI) upon the evolution of cerebral infarction in the cat. Adult cats, lightly anesthetized with nitrous oxide, underwent right middle cerebral artery (MCA) occlusion for 4 hours followed by a 2-hour period of reperfusion before sacrifice. Ten cats received 3 mg/kg TSI intravenously immediately before, and 10 cats received 3 mg/kg TSI intravenously immediately after MCA occlusion. Ten cats were used as controls receiving no treatment. The bleeding time was determined at baseline and at the end of each experiment. Electroencephalographic (EEG) recordings were obtained before and after MCA clipping and MCA release, and at hourly intervals thereafter. Regional cerebral blood flow (rCBF) was measured using the xenon-133 (133Xe) clearance technique before and after MCA occlusion, after MCA reopening, and before terminating each experiment. Thirty minutes before each cat was sacrificed, Evans blue dye and sodium fluorescein were given intravenously. The animals were then perfused with colloidal carbon and the brains removed and evaluated for midline shift. Evans blue dye and sodium fluorescein extravasation, carbon staining, and infarct size. The bleeding time, arterial blood pressure, rCBF changes, brain swelling, and vital dye extravasation were not statistically different between the three treatment groups. The EEG changes, carbon staining, and infarct size differences between the three groups also failed to reach statistical significance, but there was a suggestion that these parameters were adversely affected in the cats pretreated with TSI. Ten additional cats undergoing MCA occlusion and reperfusion were used for pharmacological studies. Five of them received 3 mg/kg TSI intravenously immediately after MCA occlusion, and serial drug and thromboxane B2 (TXB2) levels (a stable metabolite of TXA2) were determined. Another five cats were not treated and serial TXB2 levels were obtained. Production of TXA2 was inhibited by 95% in cats receiving TSI. In conclusion, thromboxane synthetase inhibition failed to modify favorably the evolution of cerebral infarction. When TSI was given before MCA occlusion, cerebral infarction tended to be more extensive.

Animals↗
PubMed1983

A method for the derivation and continuous propagation of cloned murine bone marrow macrophages.

A method is proposed for the initiation and long term propagation of clonal macrophage cell lines descended from single bone marrow precursor cells. The cells were cloned in soft agar at low cell density, and the resultant colonies were picked from the agar and expanded in liquid culture. The optimal medium for liquid culture contained 75% Dulbecco's Modified Eagle's Medium with high glucose/high bicarbonate, 10% fetal calf serum, 5% horse serum, and 10% L cell conditioned medium. During growth in liquid culture, the cells were plastic adherent but they were easily removed from polymethylpentene or polystyrene culture dishes by means of a jet of cold medium directed through a 25-gauge needle. More than 50 cell lines from 17 mouse strains have been subcultured continuously for many months, some for more than 2.5 years with no evidence of culture senescence or appreciable change in exponential growth rates. Cells from these lines were all adherent, phagocytic, Fc receptor positive, and esterase positive. Cells from each cell line tested expressed MHC-encoded surface antigens and were able to stimulate allogeneic mixed lymphocyte reactions. Using these methods of continuous culture, pure, functionally active normal macrophages could be repeatedly harvested in large numbers from any of the lines.

Animals↗
PubMed1983

Digital subtraction angiography in the evaluation of intracranial and extracranial vascular disease.

Digital subtraction angiography (DSA) is a method of visualizing the vessels of the body with the intravenous injection of contrast material. Improvements in computers, television systems, and image intensifiers have contributed to the increased image quality of DSA. With DSA, the vessels such as the carotid bifurcations and the intracranial vasculature can be visualized with a 2-3% concentration of contrast material, while with conventional angiography, the concentration of contrast in vessels is 40-50%. Using IV DSA, visualization of the carotid bifurcations is of good or excellent quality 85% of the time. In a high percentage of these cases, IV DSA replaces conventional angiography, although for imaging of the intracranial vessels, IV DSA is not as good as conventional angiography. In most tumor patients, however, conventional intracranial angiography is not needed because IV DSA combined with computed tomography gives sufficient information.

Angiography↗
PubMed1983

Metastatic periosteal osteosarcoma causing cardiac and renal failure.

The case of a 25-year-old man who had periosteal osteogenic sarcoma with intravascular metastases in unusual locations is reported. The patient presented with acute renal failure, unilateral pulmonary edema, functional mitral stenosis, and low cardiac output. After successful surgical removal of a left atrial metastasis with subsequent improvement in cardiac output, renal function improved only transiently and urinary output varied markedly. At autopsy, metastatic osteogenic sarcoma was discovered within the lumen of the abdominal aorta obstructing both renal arteries. The case is the first report of a neoplasm metastatic to the aorta causing intermittent bilateral renal arterial obstruction; it illustrates the diagnostic difficulties presented by intravascular metastatic disease.

Acute Kidney Injury↗
PubMed1983

The relationship between adjuvant and mitogenic effects of amphotericin methyl ester.

The antifungal polyene amphotericin B (AmB) and its methyl ester derivative (AME) both show potent murine immunostimulant as well as B-cell activating effects. Under certain experimental conditions, AME is a much more potent polyclonal B-cell activator (PBA) than AmB. Notable features of the murine B-cell stimulation induced by AME include: (i) High concentrations of AME (50-100 microgram/ml) are required and even at this level exhibit little or no spleen cell toxicity. (ii) Several lines of evidence suggest that the B-cell activating properties of AME are not involved in the cellular mechanism of adjuvant activity in vivo. (iii) There is a strong correlation between the magnitude of the in vitro PBA effects and the in vivo adjuvant effects of AME in a survey of different mouse strains. This evidence suggests that there is genetic control of the murine lymphoid cell-stimulatory effects of AME and that a small number of genes determines the responsive phenotype.

Adjuvants, Immunologic↗
PubMed1983

Ineffectiveness of DMSO in treating experimental brain ischemia.

A beneficial effect of dimethyl sulfoxide (DMSO) in the treatment of acute focal cerebral ischemia has not been proven. In the present study, two established experimental models of acute focal cerebral ischemia were treated with DMSO. Twenty adult cats lightly anesthetized with ketamine hydrochloride underwent right middle cerebral artery (MCA) occlusion for 6 hours. Ten cats were not treated and 10 cats received DMSO (2.5 g/kg i.v.) immediately after occlusion. No improvement of EEG findings, erythrocyte transit, regional cerebral blood flow (rCBF), blood-brain barrier permeability, or morphological findings were demonstrated in the DMSO-treated cats. In a second study, 15 conscious adult baboons underwent temporary left MCA occlusion (6 or 12 hours) using an implanted occluding device. Seven baboons were not treated and 8 baboons received continuous intravenous infusions of DMSO for 10 hours beginning 30 minutes after occlusion. Four of the baboons that were treated with DMSO also were treated with pentobarbital coma for 96 hours starting 4 hours after occlusion. Analysis of the neurological scores after 1 week survival indicated that treatment with DMSO alone and DMSO and pentobarbital coma did not improve the outcome. Morphological changes were similar in the 3 groups. The findings of our investigation indicate that DMSO is ineffective in treating acute focal cerebral ischemia.

Animals↗
PubMed1983

Brain stem auditory evoked potentials in posterior circulation surgery.

The objectives of this study were to evaluate the use of brain stem auditory evoked potentials (BAEPs) in 10 adult patients with vascular disorders of the posterior circulation that were treated surgically and to compare the BAEPs with the neurological findings. The vascular lesions included basilar artery stenosis in 3 patients, vertebral artery stenosis in 1 patient, brain stem/cerebellar arteriovenous malformation in 2 patients, and basilar artery aneurysm in 4 patients. Measurement of BAEPs were carried out during operation in all cases. Eight patients had BAEPs measured before operation, and 9 patients had BAEPs measured after operation. Repeat postoperative studies were performed in patients with changes in neurological status. In general, BAEP abnormalities correlated with the neurological findings before and after operation. Six patients had normal intraoperative studies. None of them had clinical findings of pontomesencephalic dysfunction after operation. Three patients with significant BAEP abnormalities during operation had neurological findings of pontomedullary ischemia after operation. Transient BAEP changes in 1 patient were thought to be the result of brain stem retraction. The BAEPs were lost in 3 patients who died. The use of BAEP measurement did not lengthen the operative procedures. However, the technique used in this study required 4 to 8 minutes for the accumulation and interpretation of each average, thereby delaying feedback to the surgeon. The results of this study suggest a potential role for BAEP monitoring in identifying brain stem injury during posterior circulation surgery.

Adult↗
PubMed1983

Short vein grafts for cerebral revascularization.

Experience with the use of a short saphenous vein bypass graft for cerebral revascularization is reviewed. Twenty patients with symptomatic atherosclerotic occlusive disease underwent a total of 21 bypass procedures. Cerebral revascularization was performed using a short (5 to 10 cm) saphenous vein graft (SVG) extending from the superficial temporal artery (STA) trunk anterior to the ear in 19 bypasses, or from the occipital artery (OA) immediately behind the mastoid process to the posterior temporal or angular branch of the middle cerebral artery (MCA) in two bypasses. The early patency rate for the SVG bypasses was 90%. Two of the four patients with SVG occlusion were found to have substantial resolution of a severe inaccessible internal carotid artery stenosis that was present preoperatively. Filling of multiple major branches of the MCA through the SVG was seen in 90% of patients on late postoperative conventional angiography. The STA trunk or proximal OA was consistently found to be enlarged on the late studies. None of the patients had recurrence of cerebral transient ischemic attacks. The procedure may be useful as a primary means of cerebral revascularization or as an alternative approach when a scalp artery cannot be used because of its small size, severity of arteriosclerotic changes (a common occurrence), or damage during its dissection. Cerebral blood flow studies suggest that the use of a short SVG has a more favorable effect upon the cerebral circulation than the conventional bypass procedure.

Arteriosclerosis↗
PubMed1983

Intravenous digital subtraction angiography in the assessment of patients for carotid endarterectomy.

Preoperative intravenous digital subtraction angiography (IV DSA) was compared with the operative findings in 54 patients who underwent a total of 57 carotid endarterectomies, to evaluate the accuracy of preoperative IV DSA in predicting the lesion found at surgery. Four studies early in the series were technically unsatisfactory, leaving 50 patients with 53 procedures for evaluation. Severe carotid artery stenosis was accurately predicted in all cases. Deep ulceration in the absence of severe carotid stenosis was reliably shown by IV DSA, although it was not reliably demonstrated by either IV DSA or carotid angiography if severe stenosis was also present. As severe carotid stenosis or deep ulceration are the major radiological indications for carotid endarterectomy, the authors have found that technically satisfactory IV DSA is an adequate preoperative imaging technique.

Arterial Occlusive Diseases↗