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S Black

Publications and source records attributed to S Black.

At least 109 records · Page 6Linked to original sources
PubMed1991

Ultrastructural and cytochemical evidence for single impulse initiation zones in vestibular macular nerve fibers of rat.

Cupric ion-ferricyanide labeling methods and related ferrocyanide-stained tissues were used to locate and characterize, at the ultrastructural level, presumptive impulse initiation zones in the three types of vestibular macular nerve fibers. Large-diameter, M-type vestibular nerve fibers terminate in a calyx at the heminode, and labeling is coextensive with the base of the calyx. Intermediate, M/U-type nerve fibers have short, unmyelinated preterminal segments that sometimes bifurcate intramacularly, and small-diameter, U-type nerve fibers have long, unmyelinated preterminal axons and up to three branches. Preterminals of these nerve fibers display ultrastructural heterogeneity that is correlated with labeling patterns for sodium channels and/or associated polyanionic sites. They have a nodelike ultrastructure and label heavily from near the heminode to the base of the macula. Their intramacular branches, less organized ultrastructurally, label only slightly. Results indicate that vestibular nerve fibers have one impulse initiation zone, located near the heminode, that varies in length according to nerve fiber type. Structural heterogeneity may favor impulse conduction in the central direction, and length of the impulse initiation zone could influence nerve discharge patterns.

Acoustic Maculae↗
PubMed1990

Omega-3 fatty acid treatment fails to alter alpha 1-adrenergic receptor mediated phosphoinositide turnover in streptozotocin-induced diabetic rats.

1. The effect of omega-3 fatty acid supplementation on alpha 1-adrenergic receptor-mediated phosphoinositide turnover in the hearts of 6-week streptozotocin diabetic rats was studied. 2. The diabetic state was characterized by decreased body weight gain, hypoinsulinemia and hyperglycemia. Omega-3 fatty acid treatment did not have any significant effects on the above parameters. 3. Plasma triglyceride and cholesterol levels were significantly higher in diabetic rats compared with controls. 4. Omega-3 fatty acid treatment reduced the plasma triglyceride levels in the diabetic rats, whereas plasma cholesterol levels remained unaffected. 5. Norepinephrine (10 and 100 microM) stimulated inositol monophosphate (IP1) formation was significantly decreased in the diabetic rat heart compared with controls. Omega-3 fatty acid treatment had no significant effect on the norepinephrine-mediated IP1 formation in these rats. 6. Inositol bisphosphate (IP2) formation in response to 100 microM of norepinephrine was significantly lower in the diabetic rat heart; which was also not affected by omega-3 fatty acid treatment.

Animals↗
PubMed1990

Use of the Escherichia coli SSB gene to prevent bioreactor takeover by plasmidless cells.

Reactor takeover by plasmidless cells is a major problem encountered when producing proteins from plasmid-borne genes in genetically engineered bacteria. We have approached this problem by deleting the essential ssb gene from the Escherichia coli chromosome and placing it on a plasmid. Plasmidless cells do not accumulate even after growing such strains under non-selective continuous culture conditions for extended periods of time. Other ssb-containing plasmids can be readily introduced into this E. coli strain by a plasmid-displacement technique. Using this system, we have achieved very high levels of beta-lactamase production in continuous culture without selective pressure.

Bacterial Proteins↗
PubMed1990

Preoperative and intraoperative echocardiography to detect right-to-left shunt in patients undergoing neurosurgical procedures in the sitting position.

In patients undergoing neurosurgical procedures at high risk for venous air embolism (VAE), the presence of a right-to-left shunt adds an additional risk for paradoxical air embolism (PAE). Although this is a rare complication, it can have devastating results. The most common form of right-to-left shunt is a patient foramen ovale (PFO), which can be detected by contrast echocardiography. This study evaluates the efficacy of preoperative precordial and intraoperative transesophageal echocardiography (TEE) to detect right-to-left shunting in patients undergoing neurosurgical procedures while in the sitting position. In 101 patients precordial contrast echocardiography was performed prior to surgery. The Valsalva maneuver was utilized as a provocative maneuver to facilitate demonstration of right-to-left shunting. Fifty-one of these patients also had intraoperative TEE monitoring. Right-to-left shunting was demonstrated in only six of the 101 patients examined. Of these, four were detected by TEE. This is less than the expected incidence based on the known incidence of PFO in the general population. The usefulness of preoperative ECHO as a screening test for PFO in patients undergoing neurosurgical procedures is limited, but when a PFO is found, valuable information is acquired to help manage these patients.

Cervical Vertebrae↗
PubMed1990

Cortical-basal ganglionic degeneration.

We report our experience with 15 patients believed to have cortical-basal ganglionic degeneration. The clinical picture is distinctive, comprising features referable to both cortical and basal ganglionic dysfunction. Characteristic manifestations include cortical sensory loss, focal reflex myoclonus, "alien limb" phenomena, apraxia, rigidity and akinesia, a postural-action tremor, limb dystonia, hyperreflexia, and postural instability. The asymmetry of symptoms and signs is often striking. Brain imaging may demonstrate greater abnormalities contralateral to the more affected side. Postmortem studies in 2 patients revealed the characteristic pathologic features of swollen, poorly staining (achromatic) neurons and degeneration of cerebral cortex and substantia nigra. Biochemical analysis of 1 brain showed a severe, diffuse loss of dopamine in the striatum. This condition is more frequent than previously believed, and the diagnosis can be predicted during life on the basis of clinical findings. However, as with other "degenerative" diseases of the nervous system, a definitive diagnosis of cortical-basal ganglionic degeneration requires confirmation by autopsy.

Aged↗
PubMed1990

Labetalol and esmolol in the control of hypertension after intracranial surgery.

The postoperative course of patients emerging from general anesthesia after intracranial surgery is frequently complicated by hypertension. This study examined the comparative efficacy of esmolol and labetalol in treating increases in blood pressure during emergence and recovery from anesthesia after intracranial surgery. Both esmolol and labetalol were equally effective in controlling systolic blood pressure on emergence and in the recovery room in patients undergoing intracranial surgery. However, decreases in heart rate were significantly more frequent in the immediate postoperative period in patients given labetalol. An increase in blood pressure after intracranial surgery appears to be a transitory phenomenon adequately treated with a short-acting antihypertensive agent such as esmolol.

Adrenergic beta-Antagonists↗
PubMed1990

The environment.

Explore the source record for details and available documents.

Alberta↗
PubMed1989

Word recognition and orthographic context effects in a letter-by-letter reader.

The performance of letter-by-letter readers when attempting to decipher written material gives the impression that words fail to directly evoke any higher-level representation. As a consequence, spelling patterns appear to be treated perceptually as if they were a collection of random letters. We tested the hypothesis that words are no longer mapped onto orthographic descriptions by examining the ability of a letter-by-letter reader to identify letters in familiar words, pseudowords, and random strings. A clear effect of orthographic context was obtained on the accuracy of letter recognition, indicating that spelling patterns do gain access to more central components of the reading mechanism. The implications of this result for our understanding of the syndrome are discussed.

Attention↗
PubMed1989

Serum lipoproteins are required for multiplication of Trypanosoma brucei brucei under axenic culture conditions.

Bloodstream form Trypanosoma brucei brucei IL3201 and IL3202, derived from two different serodemes, were adapted to grow in a semi-defined medium under axenic culture conditions. The organisms required low- or high-density lipoproteins, isolated from foetal bovine serum (FBS) in addition to components of lipoprotein-depleted serum, to multiply in vitro. Low- and high-density lipoproteins, isolated from a number of different species, were equally efficient at supporting in vitro growth of the parasites in medium supplemented with lipoprotein-depleted FBS. Chylomicrons and very-low-density lipoproteins did not support multiplication of the T. b. brucei and did not influence the capacity of low- or high-density lipoproteins to support parasite multiplication. Removal of the lipoprotein-lipids abrogated the capacity of low- or high-density lipoproteins to support T. b. brucei multiplication.

Animals↗
PubMed1989

Parameters affecting occurrence of paradoxical air embolism.

The effects of different patterns of ventilation and intravascular volume infusion on the occurrence of paradoxical air embolism (PAE) were evaluated in 15 pigs with a surgically created atrial septal defect (ASD). A balloon atrial septostomy was created transvenously in anesthetized pigs (mean diameter 8.6 mm +/- 1 mm). Monitoring included transesophageal echocardiography (TEE) of the right and left heart, ECG, EEG, direct arterial pressure, right and left atrial pressures (RAP and LAP), pulmonary artery pressure, and pulmonary capillary wedge pressure (PCWP). With the animal in a head up tilt, air was infused into the superior vena cava at a rate of 0.27 ml.kg-1.min-1 for 6 min or until PAE was identified on the TEE. Four situations were studied--intermittent positive pressure ventilation (IPPV), intermittent positive pressure ventilation with 10 cm H2O positive end-expiratory pressure (PEEP), spontaneous ventilation, and IPPV following infusion of 500 ml hetastarch. The incidence of PAE was not different in any of the four situations. Release of PEEP resulted in an increase in the amount of PAE or new PAE in nine of 14 animals. PAE occurred both with and without mean RAP exceeding mean LAP and the incidence of PAE was not significantly different based on the atrial pressure gradient. In situations during which the mean LAP remained greater than mean RAP throughout the venous air infusion and PAE occurred, transient reversal of the right to left atrial pressure gradient during a portion of each cardiac cycle was demonstrated.

Animals↗
PubMed1988

Esmolol for the control of hypertension after neurologic surgery.

We sought to evaluate the effectiveness of esmolol vs placebo in 40 patients emerging from general anesthesia for neurosurgery. Efficacy was defined as a decrease in systolic blood pressure to within 20% above average ward pressure. The need for additional antihypertensive agents to control blood pressure was also used to define efficacy. During the infusion period 20 of 21 (95%) of the esmolol-treated patients and two of 19 (11%) of the patients receiving placebo had return of systolic blood pressure to within 20% of average ward pressure (p less than 0.001). One out of 21 (5%) esmolol-treated patients and 14 of 19 (74%) of the placebo group required intervention with additional antihypertensive medications (p less than 0.001). Esmolol was found to be effective in controlling hypertension that develops on emergence from general anesthesia in patients undergoing neurosurgery.

Adrenergic beta-Antagonists↗