Search PubMed⌕ Search

Biomedical subjects

J R Little

Publications and source records attributed to J R Little.

At least 73 records · Page 4Linked to original sources
PubMed1987

Cerebral circulation during arteriovenous malformation operation.

The circulatory changes in the cortex around a cerebral arteriovenous malformation (AVM) were studied in 18 patients. The AVMs had rapid circulation times with early draining veins on angiography. Local cortical blood flow (lCoBF) was measured with cortically applied thermister/Peltier stack arrays. The AVMs had a more pronounced effect on lCoBF at a 2- to 4-cm distance from the AVM margin than in the adjacent cortex. Mean preexcision lCoBF was 62.9 +/- 6.7 (SE) ml/100 g/minute (i.e., similar to normal controls) near the AVM margin and 43.0 +/- 4.2 ml/100 g/minute far (i.e., greater than 2 cm) from the AVM. CO2 reactivity (COR) before excision was 1.1 +/- 0.3 ml/100 g/minute/torr of CO2 (i.e., similar to normal controls) at near sites and 0.6 +/- 0.3 ml/100 g/minute/torr of CO2 at far sites. The mean postexcision near lCoBF remained stable at 55.8 +/- 5.1 ml/100 g/minute at near sites, but the far lCoBF significantly increased (P less than 0.05) to 57.2 +/- 6.8 ml/100 g/minute. The cortical feeding artery pressure was substantially below the normal cortical artery pressure in 50% of the cases studied. Pressure in these arteries normalized after occlusion and AVM excision, resulting in a rapid increase in cortical artery perfusion pressure. Draining red vein pressure, which was elevated before AVM excision, also dropped after excision, contributing to the increase in perfusion pressure. Two patients who developed the normal perfusion pressure breakthrough syndrome (PBS) after operation had low lCoBF and disturbed COR before AVM excision and marked increase of lCoBF after excision.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1987

Thoracic spinal canal stenosis.

Hypertrophy of the posterior spinal elements leading to compromise of the spinal canal and its neural elements is a well-recognized pathological entity affecting the lumbar or cervical spine. Such stenosis of the thoracic spine in the absence of a generalized rheumatological, metabolic, or orthopedic disorder, or a history of trauma is generally considered to be rare. Over a 2-year period the authors have treated six cases of thoracic myelopathy associated with thoracic canal stenosis. In four patients the deficits developed gradually and painlessly. The three older patients had a clinical profile characterized by complaints of pseudoclaudication, spastic lower limbs, and evidence of posterior column dysfunction. Two patients were younger adults with low thoracic myelopathy associated with local back pain after minor trauma. Both patients also had congenital narrowing of the thoracic spinal canal. Oil and metrizamide contrast myelography in the prone position were of limited value in diagnosing this condition; in fact, myelography may be misleading and result in erroneous diagnosis of thoracic disc protrusion, when the principal problem is dorsal and lateral compression from hypertrophied facets. Magnetic resonance imaging and computerized tomography sector scanning were more useful in the diagnosis of this disorder than was myelography. Thoracic canal stenosis may be more common than is currently recognized and account for a portion of the failures in anterior and lateral decompression of thoracic disc herniations.

Adult↗
PubMed1986

Proton magnetic resonance imaging in ischemic cerebrovascular disease.

Proton magnetic resonance imaging (MRI) using a 0.6- or 1.5-Tesla superconductive magnet was compared with high-resolution computed tomography (CT) in 60 patients with transient ischemic attacks (TIAs) or brain infarction. MRI showed focal parenchymal changes in 84% of patients with TIAs, whereas CT showed similar changes in 42%. The sensitivity of MRI was also greater in patients with infarcts, but the difference between CT and MRI was not as great. Infarcts were usually better delineated by MRI regardless of location. However, MRI failed to reveal cortical infarcts that were clearly seen on contrast-enhanced CT scans and was unable to clearly distinguish subacute from chronic hemorrhagic infarcts. MRI changes were best detected with T2-weighted images and usually appeared as multiple areas of increased signal intensity in the subcortical and periventricular white matter. MRI changes often could not be correlated with the clinical history and neurological findings; identical changes have been seen in patients with no history of cerebrovascular disease.

Acute Disease↗
PubMed1986

Disseminated coccidioidomycosis in a patient with the acquired immune deficiency syndrome.

Disseminated coccidioidomycosis is a recognized but infrequent accompaniment of the acquired immune deficiency syndrome (AIDS). A patient with AIDS, Pneumocystis carinii pneumonia, and disseminated coccidioidomycosis occurring outside of an endemic area is described. Fungal infection presented atypically with progressive thoracic adenopathy and the development of cold soft tissue abscesses. As is often the case with AIDS, serologic testing proved to be unreliable and tissue biopsy the only means of accurate diagnosis.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Pituitary apoplexy: a complication of cardiac surgery.

Pituitary apoplexy occurred in 3 patients in the immediate postoperative period following cardiac operation with cardiopulmonary bypass. In this setting, this complication is extremely rare and not widely recognized. Precipitating factors may be related to the extracorporeal bypass apparatus, anticoagulation, low cerebral blood flow, and even anesthetic agents. Neurosurgical decompression can be safely performed in the early postoperative period following open-heart operations.

Cardiopulmonary Bypass↗
PubMed1986

Improved neurological outcome in experimental focal cerebral ischemia treated with propranolol.

Propranolol has been shown to exert a protective effect in experimental myocardial, renal, and early acute focal cerebral ischemia. However, propranolol was not found to reduce infarct size in nitrous oxide-anesthetized, paralyzed, mechanically ventilated cats subjected to 6 hours of acute focal ischemia. The objective of the current investigation was to study further the effects of racemic (d,l)-propranolol on the evolution of acute focal cerebral ischemia in awake, conscious cats. Adult cats were anesthetized with halothane and underwent the implantation of an occluding device around the right middle cerebral artery. After a 48-hour recovery period, the right middle cerebral artery was occluded for 6 hours and then reopened, allowing reperfusion for an additional 6 hours. Neurological examinations were conducted every 2 hours throughout each experiment. Ten cats received d,l-propranolol (2 mg/kg) 1 hour before occlusion, immediately before occlusion, and every 2 hours throughout each experiment. Eleven cats serving as controls were not treated. The neurological examination significantly improved over time in the treated group when compared to the untreated group (P = 0.01). Carbon filling defects, gross brain swelling, and infarct size were reduced in treated cats. The results of this study suggest that propranolol does have beneficial effects in acute focal cerebral ischemia.

Anesthesia, General↗
PubMed1986

Retinal artery pressure and cerebral artery perfusion pressure in cerebrovascular occlusive disease.

The objectives of the investigation were to measure the retinal artery pressure (RAP) and cortical artery pressure (CAP) in patients undergoing superficial temporal artery to middle cerebral artery (STA-MCA) bypass, to study the relationship between these pressures, and to evaluate our ability to predict CAP on the basis of RAP. The 44 patients undergoing bypass surgery included 26 with ipsilateral internal carotid artery (ICA) occlusion (Group I), 5 with bilateral ICA occlusion (Group II), 4 with inaccessible ICA stenosis proximal to the ophthalmic artery (OA) (Group III), 2 with ICA stenosis distal to the OA (Group IV), 3 with ICA occlusion distal to the OA (Group V), 2 with MCA stenosis (Group VI), and 2 with MCA occlusion (Group VII). Five patients undergoing craniotomy for an asymptomatic saccular aneurysm were used as controls. Mean RAP (MRAP) was measured by ophthalmodynamometry (ODM) and was expressed as a ratio of the mean systemic arterial blood pressure (i.e., MRAP/MSAP). The mean MRAP/MSAP for combined Groups I, II, and III with ICA occlusion proximal to the OA was significantly lower than both the control group (P = 0.0001) and the combined Groups IV, V, VI, and VII with occlusive lesions distal to the OA (P = 0.0001). Six patients in Groups I and II with venous stasis retinopathy had a mean MRAP/MSAP of 0.18 +/- 0.11. Mean cortical artery pressure (MCAP) was measured by inserting a 26 gauge needle into a small cortical artery and was expressed as the MCAP/MSAP ratio. Mean MCAP/MSAP was less than 0.50 for all groups except Group III.(ABSTRACT TRUNCATED AT 250 WORDS)

Arterial Occlusive Diseases↗
PubMed1986

Fusiform basilar artery aneurysm in a 33-month-old child.

A 33-month-old girl presented with acute subarachnoid hemorrhage from a ruptured multilobulated fusiform aneurysm of the midbasilar artery. This rare lesion was treated surgically by occluding the basilar artery. Intraoperative brain stem auditory evoked potential and somatosensory evoked potential monitoring results did not change with basilar artery occlusion, suggesting that the occlusion would be tolerated. However, the amplitudes of brain stem auditory evoked potential Waves III-V to right ear stimulation were transiently reduced during left pontine retraction during the aneurysm exposure. The patient made a complete clinical recovery.

Aneurysm↗
PubMed1985

Modulation by lipoproteins of amphotericin B-induced immunostimulation.

Previous reports indicate that amphotericin B (AmB) and amphotericin methyl ester (AME) are potent adjuvants and polyclonal B-cell activators, and that most mouse strains can be classified as high or low responders to AmB and AME. In the present study, an inbred strain with very high plasma cholesterol concentration (HC strain) proved to be a low responder. Responses of HC mice to other immune stimuli were normal, suggesting that HC lymphoid cells expressed selectively weak responses to AmB and AME. Plasma levels of low-density lipoproteins (LDL), very-low-density lipoproteins (VLDL), and high-density lipoprotein subfraction (HDL2) were very much higher in HC mice than in AKR mice, an AmB-high responder strain. Low responses in vitro to AME were observed with lymphoid cells from HC mice and from AKR----HC bone marrow chimeras, i.e., AmB-high responder strain lymphocytes from a low responder host. However, enhanced AME responses were induced by a 2- or 48-hr preincubation of splenocytes from either HC or AKR mice in medium containing lipoprotein-depleted fetal calf serum. Taken together these studies indicate that plasma lipoproteins can inhibit lymphocyte responses to AME; this seems to account for the low AmB and AME responses of the HC strain. The mechanism of this lipoprotein-induced inhibition remains obscure, but it cannot be accounted for by competitive binding of AmB by lipoproteins.

Adjuvants, Immunologic↗
PubMed1985

Air embolism in the operating room.

If left undetected and untreated in the operating room, air embolism can be a potentially lethal event. It is important to be aware of the specific positions and surgical procedures that put a patient at risk for air emboli. This article will define air embolism, discuss its occurrence and effects on the body, review specific monitoring techniques used to detect intravascular air, and present techniques used for prevention and treatment by the operating room staff.

Blood Pressure Determination↗
PubMed1985

In vitro and in vivo comparisons of amphotericin B and N-D-ornithyl amphotericin B methyl ester.

N-D-Ornithyl amphotericin B methyl ester (N-D-ornithyl AmE) has a lower toxicity for animals than does amphotericin B (AmB), and peak serum levels can be achieved that are fourfold higher than those obtained with an equivalent dose of AmB. However, N-D-ornithyl AmE has one-fourth the in vitro activity and between one-fifth and one-eighth the in vivo activity of AmB. N-D-ornithyl AmE and the corresponding lysyl derivative also lack the immunoadjuvant effects of AmB.

Adjuvants, Immunologic↗
PubMed1985

Treatment of acute focal cerebral ischemia and recirculation with d-propranolol.

The purpose of the investigation was to evaluate the effects of d-propranolol upon temporary cerebral ischemia followed by a period of reperfusion, that is, a situation analogous to major cerebral artery embolization. Twenty adult cats, lightly anesthesized with nitrous oxide, underwent 4 hours of right middle cerebral artery (MCA) occlusion and 2 hours of recirculation. Ten cats were untreated and 10 cats received d-propranolol, the weak beta-blocking isomer of racemic (d,l) propranolol. The d-propranolol was infused directly into the right carotid artery at doses of 2 mg/kg, given as a bolus immediately before MCA occlusion, and 0.33 mg/kg/hour, given continuously for 6 hours beginning immediately after MCA occlusion. Systemic arterial blood pressure was similar in both groups, but heart rate was transiently reduced in the treated group immediately after the bolus injection of d-propranolol and MCA occlusion. Regional cerebral blood flow (rCBF), measured by the xenon-133 clearance technique, was not significantly different in the ischemic, right hemisphere. Electroencephalographic (EEG) activity changes in the ischemic, right hemisphere were similar in both groups, but there was significant deterioration of EEG activity in the left, nonischemic hemisphere of untreated cats after MCA reopening. Swelling of the ischemic, right hemispheres was similar in both groups and more severe than in previous studies wherein there was no recirculation phase. Carbon perfusion and blood-brain barrier changes were also similar. The results of the study failed to show a protective effect despite theoretical beneficial actions of d-propranolol. Also, the study demonstrated that d-propranolol does not have a detrimental effect upon rCBF in acute focal cerebral ischemia.

Animals↗
PubMed1985

Resolving occlusive lesions of the basilar artery.

Progression of severe basilar artery stenosis to occlusion is a well-recognized phenomenon, but regression of a severe basilar artery atherothrombotic lesion has not been described previously. In this report, two patients with a symptomatic severe basilar artery occlusive lesion showed substantial angiographic improvement after 3 months of anticoagulation in one case and 4 months after superficial temporal artery to superior cerebellar artery bypass in the other case. The findings in these cases indicate that clinical improvement in similar cases may reflect recanalization of a basilar artery occlusive lesion. The uncertain natural history and potential for regression of symptomatic basilar artery atherothrombosis make us hesitant to recommend posterior circulation revascularization immediately after such lesions are first demonstrated angiographically.

Basilar Artery↗
PubMed1985

Improvement in the retinal circulation after superficial temporal to middle cerebral artery bypass.

The retinal circulation of 35 patients (age, 30 to 71 years) with symptomatic internal carotid occlusion (22 cases) or severe inaccessible stenosis (13 cases) was studied both before and after superficial temporal to middle cerebral artery (STA-MCA) bypass surgery using ophthalmodynamometry (ODM) and intravenous fundus fluorescein angiography (IVFA). Ninety-four per cent of the patients were found preoperatively to have funduscopic findings or symptoms indicative of ocular ischemia. ODM values were abnormal preoperatively in 32 of 35 patients (91%), and improvement in ODM values for the ipsilateral eye was noted postoperatively in 25 patients (71%). ODM values obtained during the early (less than 3 months) and late (greater than 3 months) postoperative periods were significantly improved when compared to the preoperative values. IVFA values were abnormal in 25 of 29 patients (86%) preoperatively, and significant improvement was noted in 22 of 25 patients (88%) postoperatively. Preoperative patients with normal fundus examinations (10 cases) had significantly better values for IVFA and ODM than patients with venous stasis retinopathy. The findings of the study showed that STA-MCA anastomosis is beneficial in treating retinal ischemia secondary to ipsilateral severe inaccessible carotid artery stenosis or occlusion.

Adult↗
PubMed1984

Growth inhibition of Cryptococcus neoformans by cloned cultured murine macrophages.

Cloned and unselected bone marrow-derived macrophage cell lines were obtained from A/J, AKR/J, BIO.A(5R), CBA/J, DBA/2, HPC, NZW, and [NZB X NZW]F1 mice, and their interactions were studied in vitro with a lightly encapsulated natural serotype A isolate of Cryptococcus neoformans. Growth inhibition of C. neoformans was seen with all of the cell lines, as determined by enumeration of colony-forming units. Inhibition was enhanced by a high concentration (8%) of fresh mouse serum and was the same for serum obtained from AKR/J (C5 deficient) and BIO.A (C5 normal) mice. Macrophage incubation with fresh AKR/J serum which had been absorbed with heat-killed Cryptococcus cells also inhibited C. neoformans growth. Heat-inactivation, EDTA addition or anti-C3 antibody treatment of fresh serum abolished the opsonic activity for C. neoformans, while EGTA addition to fresh serum was without effect on opsonization. In addition, neither IgM nor IgG1 murine monoclonal antibodies specific for C. neoformans enhanced phagocytosis or killing of the yeast by macrophages. These findings are consistent with the interpretation that C3b is an important modulator of interactions between macrophages and C. neoformans.

Animals↗
PubMed1984

Carbon tetrachloride nephrotoxicity: a reassessment of pathophysiology based upon the urinary diagnostic indices.

Inhalation or ingestion of carbon tetrachloride (CCl4) has been said to result in the nephrotoxic lesion of acute tubular necrosis (ATN). We describe three patients who inhaled toxic quantities of CCl4 and presented with oligoanuria and severe hepatoxicity. All patients developed protracted vomiting and were unable to maintain fluid intake for several days prior to our evaluation. Physical examination, urinalysis, and calculated FENa, FEH2O, and renal failure index (RFI) indicated that the acute oliguric renal failure was "prerenal" due to marked extracellular fluid (ECF) volume contraction. Aggressive volume repletion restored renal function to normal in each patient. It is suggested that the acute renal failure following CCl4 exposure begins as a functional disorder and may progress to ATN if volume depletion is not recognized and corrected. Early and aggressive volume repletion will reverse this prerenal state and may prevent the later onset of ATN following CCl4 exposure.

Acute Kidney Injury↗