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Biomedical subjects

J R Little

Publications and source records attributed to J R Little.

At least 109 records · Page 6Linked to original sources
PubMed1983

Campylobacter enteritis from untreated water in the Rocky Mountains.

During the summers of 1980 and 1981 Campylobacter jejuni was isolated from 23% and Giardia lamblia was isolated from 8% of persons with diarrheal disease acquired in the area of Grand Teton National Park, Wyoming. Campylobacter enteritis occurred most frequently in young adults who had been hiking in wilderness areas and was significantly associated with drinking untreated surface water in the week before illness (p less than 0.02 in 1980; p less than 0.005 in 1981). Penner serotype 4 was the commonest serotype isolated from humans and the only serotype isolated from an implicated mountain stream. These studies show that backcountry surface water can be an important source of C. jejuni and that infection with Campylobacter, as well as G. lamblia, should be considered as a cause of diarrhea in those who have recently returned from wilderness areas.

Adult↗
PubMed1983

Immune enhancement in mice by ara-A.

Ara-A in single, apparently nontoxic doses stimulates murine immune responses to several well-defined antigens. Both humoral and cell-mediated responses are enhanced by ara-A, but not all mouse strains respond equally well. In certain mouse strains, ara-A also promotes increased (or decreased) survival during experimental infection with Cryptococcus neoformans, suggesting that clinically significant effects on host resistance may result from the use of ara-A as an antiviral therapeutic agent. The biochemical mechanisms of action of the aranucleosides suggest that the immunostimulation produced by ara-A depends on suppressor cell toxicity.

Adjuvants, Immunologic↗
PubMed1983

Digital subtraction angiography in the evaluation of cerebrovascular disease.

Intravenous DSA provides a safe, accurate, and cost-effective means of examining the extracranial and intracranial vasculature on an inpatient or outpatient basis. Intra-arterial DSA provides better spatial resolution than IV-DSA and has advantages over conventional film-screen angiography. The authors demonstrate the applications and limitations of this revolutionary diagnostic technique.

Carotid Artery Diseases↗
PubMed1982

Intravenous digital subtraction angiography in brain ischemia.

Recent advances in computer and radiological technology have permitted a reassessment of intravenous (IV) angiography in the evaluation of extracranial and intracranial vessels. This report reviews our initial experience with IV digital subtraction angiography in the diagnosis and treatment of brain ischemia. Two hundred seventy-three IV digital subtraction angiograms (146 extracranial, 127 intracranial) were performed on a total of 178 patients with suspected cerebral ischemia (159 patients), brainstem/cerebellar ischemia (13 patients), or asymptomatic bruit (six patients). Extracranial studies clearly demonstrated ulceration, stenosis, and occlusion of the carotid arteries. Intracranial studies usually detected major artery occlusive disease and provided insight into the collateral flow patterns. Intravenous digital subtraction angiography allowed the accurate assessment of arteries after carotid endarterectomy and brain bypass surgery. Although conventional angiography was usually recommend in patients treated surgically, IV digital subtraction angiography obviated the need for conventional studies in the initial evaluation of many patients.

Arterial Occlusive Diseases↗
PubMed1982

Correlation of clinical and angiographic findings in brain ischemia with regional cerebral blood flow measured by the xenon inhalation technique.

Eighty-eight patients with brain ischemia underwent cerebral angiography and measurement of regional cerebral blood flow (rCBF) after 133Xe inhalation. A fast compartment flow rate and an initial slope index were computed for each detector and for each hemisphere. The clinical presentation, angiographic findings, and rCBF results were then examined for significant correlations. Patients with hemispheric infarction most frequently showed bilateral diffusely decreased rCBF. In patients with transient ischemic attacks, no specific pattern emerged. Patients with unilateral internal carotid artery occlusion frequently hd bilateral diffusely decreased rCBF. Patients with severe internal carotid artery stenosis were more likely to show decreased rCBF than were patients with mild or moderate stenosis. The initial slope index seemed to be a more sensitive indicator of brain ischemia than the fast compartment flow rate. The possible pathophysiological significance and relationship to patient management of the various rCBF patterns are discussed.

Brain Ischemia↗
PubMed1982

Digital subtraction angiography of the intracranial vascular system: comparative study in 55 patients.

Intracranial vessels were examined in 55 patients with both conventional selective catheterization and intravenous digital subtraction angiography using a prototype digital subtraction unit. In 65% of the patients, the digital subtraction angiogram was diagnostic, but the overall quality was inferior to conventional selective angiography. In 22%, the digital subtraction angiogram provided diagnostic information, but there was a significant chance of misinterpreting the results of the study. In 13% of cases, the subtraction angiogram was not diagnostic. As now developed, digital subtraction angiography can replace conventional cerebral angiography for preoperative evaluation of the juxtasellar carotid artery prior to transphenoidal surgery because the large intracerebral vessels are consistently well visualized with digital subtraction. The dural sinuses are better visualized with digital subtraction than with conventional angiography because with digital subtraction all the vessels of the brain are opacified, whereas with conventional angiography, there is a mixture of opacified and unopacified blood in the sinuses. Combined with computed tomography, digital subtraction angiography can replace conventional angiography for determining the preoperative extent and vascularity of tumors. It can be used for postoperative evaluation of aneurysms, arteriovenous malformations, extracranial to intracranial bypasses, and after the embolization of vascular lesions.

Adult↗
PubMed1981

Digital subtraction angiography of the carotid arteries: a comparative study in 100 patients.

Conventional angiography and intravenous digital subtraction angiography (DSA) were used to examine the common carotid artery bifurcations in 100 patients with clinically suspected arteriosclerotic disease. In 60% of the patients, the quality of the DSA examination was good or excellent bilaterally; in 23%, the quality was good or excellent on one side; in the remaining 17%, both bifurcations were poorly visualized. There was excellent correlation of conventional and digital angiograms when the carotid bifurcations were well visualized with DSA (sensitivity 95%, specificity 99%, accuracy 97%). When the carotid bifurcations were not well visualized with DSA, there was a substantial chance for misinterpretation of the study (sensitivity 54%, specificity 70%, accuracy 64%). Digital subtraction angiography is a safe, rapid procedure that can be performed on an outpatient basis and can accurately evaluate the carotid bifurcation in approximately 70% of the arteries examined.

Adult↗
PubMed1981

Treatment of acute focal cerebral ischemia with dimethyl sulfoxide.

The object of this investigation was to study the effects of dimethyl sulfoxide (DMSO) upon the evolution of cerebral infarction. Twenty adult cats anesthetized lightly with ketamine hydrochloride underwent right middle cerebral artery occlusion for 6 hours. Ten cats were not treated and 10 cats received DMSO (2.5 g/kg i.v.) immediately after occlusion. Regional cerebral blood flow (rCBF) changes in the right sylvian region were similar in the untreated and treated groups. The mean rCBF before occlusion was 46 +/- 10 ml/100 g/minute in the untreated group and 45 +/- 10 ml/100 g/minute in the treated group. Eight cats in both groups had rCBF measurements consistently below 18 ml/100 g/minute during the 6-hour period after occlusion. An index of erythrocyte flow was determined by measuring the transit of technetium-99 (99Tc)-labeled erythrocytes in the right sylvian region. The period of erythrocyte transit before occlusion was 10 +/- 1 seconds in the untreated group and 10 +/- 2 seconds in the treated group. After 6 hours of occlusion, the erythrocyte transit time was 18 +/- 3 seconds in the untreated group and 19 +/- 3 seconds in the treated group. Increasing delay in erythrocyte transit during the 6-hour occlusion period was seen in 5 untreated cats and 6 treated cats and was thought to represent a progressive increase in microvascular resistance. The complete washout of erythrocytes indicated the absence of microcirculatory obstruction. Electroencephalography (EEG) showed a reduced amplitude of activity in the right cerebral hemisphere after occlusion in cats with an rCBF consistently below 18 ml/100 g/minute. No significant EEG differences were found between the untreated and treated groups. Treatment with DMSO failed to modify the developing ischemia edema, neuronal alterations, or the changes in blood-brain barrier permeability to Evans blue dye and fluorescein. In this study DMSO was ineffective in preventing ischemic damage or acted when irreversible injury had already taken place.

Acute Disease↗
PubMed1981

Intravenous digital subtraction angiography: application to cerebrovascular surgery.

Intravenous digital subtraction angiography (DSA) was used to evaluate the extracranial and/or intracranial arteries of 87 patients with suspected cerebrovascular disorders. The examinations were performed on either an inpatient or an outpatient basis. Renografin-76 was injected into an arm vein through an angiocatheter. Extracranial examinations accurately demonstrated major artery disease such as carotid artery occlusion, stenosis, and ulceration. Intracranial examinations demonstrated an aneurysm in 9 of 10 patients and an arteriovenous malformation in 5 patients. The technique was useful in assessing the results of cerebrovascular procedures such as carotid endarterectomy, superficial temporal artery to middle cerebral artery bypass, and the obliteration of vascular anomalies. DSA also excluded the presence of an intrasellar aneurysm and showed the location of the intracranial arteries before trans-sphenoidal surgery. The findings of the DSA examinations correlated closely with the findings of conventional angiography.

Brain Ischemia↗
PubMed1981

Treatment of acute focal cerebral ischemia with concentrated albumin.

The object of the investigation was to study the effects of concentrated albumin upon the evolution of cerebral infarction. 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 concentrated (i.e., 25 g/100 ml) human serum albumin (5 ml/kg i.v.) at the time of MCA occlusion. The blood volume increased 30 to 40% in the cats receiving concentrated albumin. The hematocrit fell for 32 +/- 5% (SD) before occlusion to 23 +/- 6% at 2.5 hours after occlusion in treated cats, whereas the hematocrit in untreated cats remained stable at 35 +/- 5. Regional cerebral blood flow (rCBF) changes in the right sylvian region were similar in the untreated and treated groups. The mean rCBF before occlusion was 42 +/- 11 ml/100 g/minute in the untreated cats and 44 +/- 8 ml/100 g/minute in the treated cats. Untreated and treated cats had similar reductions of rCBF in the right sylvian region to less than or equal to 18 ml/100 g/minute at some point after occlusion. An index of erythrocyte flow and microcirculatory resistance was determined by measuring the transit of 99Tc-labeled erythrocytes in the right sylvian region. The erythrocyte transit time before occlusion was 10 +/- 2 seconds in the untreated group and 9 +/- 1 seconds in the treated group. After 6 hours, the erythrocyte transit was 19 +/- 3 seconds in the untreated group and 15 +/- 3 seconds in the treated group (p less than or equal to 0.1), suggesting that less microcirculatory impairment occurred in some treated cats. Electroencephalographic changes during the initial 3 hours of occlusion were less severe in the treated cats than in the untreated cats, suggesting that the collateral flow in the border zone of the MCA territory initially may have been improved by treatment. Impairment of carbon perfusion, ischemic edema, and neuronal alterations after 6 hours of occlusion were the same in both groups. Increased permeability of the blood-brain barrier to Evans blue dye, however, was more marked in the treated group. The findings of the study indicate that concentrated albumin does not substantially modify the evolution of cerebral infarction.

Animals↗
PubMed1981

Oxygenated fluorocarbon perfusion as treatment of acute spinal cord compression injury in dogs.

Experiments were conducted to determine the therapeutic value of subarachnoid perfusion of the traumatized dog spinal cord with the fluorocarbon, Fluosol-DA (20%). Control dogs without lesions, but which had durotomy, subarachnoid catheter placement, and saline irrigation for 4 hours, did not have any residual neurological deficit. A series of 41 dogs underwent an acute spinal cord compression using an epidural balloon inflated to a pressure of 160 mm Hg and maintained for 1 hour. Treatment included durotomy only (11 dogs), durotomy with saline perfusion at room temperature (15 dogs), and durotomy with oxygenated Fluosol-DA perfusion at room temperature (15 dogs). The dogs underwent daily grading of neurological status for a 60-day period. Dogs undergoing perfusion of the spinal cord with either saline or oxygenated Fluosol-DA had significantly improved motor recovery (p less than 0.004) compared with dogs undergoing durotomy only. Perfusion with oxygenated Fluosol-DA resulted in significantly better motor recovery (p less than 0.05) than did perfusion with normal saline. Microscopic examination of the traumatized spinal cords failed to reveal a substantial difference between the three groups. However, dogs with better functional results tended to have less destruction of the white matter. Hemorrhagic necrosis of the central gray matter was consistently observed in all traumatized spinal cords.

Animals↗
PubMed1980

Effect of exogenous lipids and lipoproteins on the primary immune response in vitro.

Cholesterol and certain lipoproteins have regulatory effects on the primary immune responses of murine spleen cells in vitro. The plaque-forming cell (PFC) responses to sheep red blood cells of trinitrophenylated Brucella abortus were studied in complete, lipid-depleted or lipoprotein-reconstituted media. The requirement for exogenous low density lipoprotein (LDL) and its cholesterol moiety was established by comparison of the yield of PFC in cell cultures deprived of lipoproteins with that in cultures to which specific classes of lipoproteins were added. The spleen cells in complete medium yielded about 10-fold greater PFC responses than cells in lipoprotein-deficient medium. In lipoprotein-deficient media, human LDL completely reversed the decreased immune response, LDL lipids and free cholesterol partially reversed the deficit, the human high density lipoproteins and an apo B phospholipid complex were ineffective. In complete media, cholesterol at higher concentrations (100--200 microgram/ml) and LDL lipids partially inhibited the primary immune response. Exogenous cholesterol was required for the in vitro response to both thymus-dependent and thymus-independent antigens.

Animals↗