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Biomedical subjects

W A Taylor

Publications and source records attributed to W A Taylor.

At least 19 recordsLinked to original sources
PubMed1998

Lysophosphatidylcholine inhibits cardiolipin biosynthesis in H9c2 cardiac myoblast cells.

The effect of phospholipase A2 treatment on cardiolipin biosynthesis was investigated in intact H9c2 cardiac myoblasts. Treatment of cells with Naja mocambique mocambique phospholipase A2 reduced the pool sizes of phosphatidylcholine and phosphatidylethanolamine compared with controls. The pool sizes of lysophosphatidylcholine and lysophosphatidylethanolamine were elevated, whereas the pool sizes of cardiolipin and other phospholipids were unaffected by phospholipase A2 treatment. Pulse labeling experiments with [1,3-3H]glycerol and pulse-chase labeling experiments with [1,3-3H]glycerol were performed in cells incubated or preincubated in the absence or presence of phospholipase A2. In all experiments, radioactivity incorporated into cardiolipin was reduced in phospholipase A2-treated cells with time compared with controls, indicating attenuated de novo biosynthesis of cardiolipin. The mechanism for the reduction in cardiolipin biosynthesis in phospholipase A2-treated cells was a decrease in the activity of phosphatidic acid:cytidine-5'-triphosphate cytidylyltransferase, the rate-limiting enzyme of cardiolipin biosynthesis, mediated by elevated cellular lysophosphatidylcholine levels. The results suggest that de novo cardiolipin biosynthesis in H9c2 cells may be regulated by the cellular level of lysophosphatidylcholine.

Animals↗
PubMed1997

The long-term outlook for hydrocephalus in childhood. A ten-year cohort study of 155 patients.

Despite the fact that ventriculoperitoneal shunt insertion is the most commonly performed surgical operation in the pediatric neurosurgeon's repertoire, there is a surprising paucity of long-term outcome studies for these patients detailing either the complication rate over a predetermined time period or more importantly their intellectual outcome. The aims of this study, therefore, were to determine the 10-year outcome in a cohort of 155 children with shunted hydrocephalus, both in terms of the number and time sequence of shunt complications and also the long-term academic (schooling) outcome of these individuals. This was a cohort study of 155 hydrocephalic children who underwent first-time ventriculoperitoneal shunt insertion between the years 1978 and 1983, who were then followed up on an annual outpatient basis for a period of 10 years or until death. Their academic records and the surgical morbidity and mortality encountered over the 10-year study period were used as the main outcome measures. For those children surviving until schoolage, 59% were able to attend a normal school. The academic outlook for those children with hydrocephalus secondary to infection (postmeningitic) or intraventricular hemorrhage was less favorable with 52 and 60% requiring special schooling compared to those children with congenital hydrocephalus (29%; p = 0.036). 44% (68/155) of patients in this cohort did not require a shunt revision. The commonest reasons for shunt revision were blockage (49%) and infection (19%) which predominantly occurred within the first year of their original shunt procedure. Overall the infection rate was 12% (44/380 procedures). Furthermore an increased incidence of shunt infection was noted in those under 6 months old (p = 0.040). There was an 11 % mortality during the 10-year follow-up period for those with nontumor-related hydrocephalus.

Cerebral Hemorrhage↗
PubMed1995

Timing of postoperative intracranial hematoma development and implications for the best use of neurosurgical intensive care.

This study records the incidence and timing of postoperative hematomas in neurosurgical patients and analyzes the best use of neurosurgical intensive care. In 2305 patients undergoing freehand or stereotactic biopsy, elective or emergency craniotomy, or posterior fossa surgery, 50 (2.2%) developed a hematoma. Clinical deterioration as a result of postoperative hematoma occurred within 6 hours of surgery in 44 patients and more than 24 hours after surgery in six patients. Although patients undergoing posterior fossa surgery or emergency craniotomy warrant longer periods of intensive-care observation, patients having elective supratentorial operations can safely be transferred to a neurosurgical ward for observation, provided they have regained their preoperative neurological status by 6 hours postsurgery.

Cerebral Hemorrhage↗
PubMed1994

Testicular and epididymal sperm content in grazing Cashmere bucks: seasonal variation and prediction from measurements in vivo.

Each month, for 15 months, the testes and epididymides were recovered from five Australian cashmere bucks selected at random from a group of mature bucks (initial n = 116) at pasture (location 29 degrees S, 153 degrees E). The extent of seasonal change in testicular and epididymal sperm reserves was determined and indirect methods for predicting these reserves were developed. Paired testicular weight exhibited clear seasonal variation from 137 g in August to 269 g in February. The total elongated spermatid content of the testes, determined by homogenization, showed a very similar seasonal pattern, ranging from 13.8 x 10(9) in September to 36.2 x 10(9) in March. Seasonal changes of similar timing were observed for paired epididymal weight and sperm content. Although changes in total testicular spermatid content were largely the result of change in testicular weight (R2 = 0.72, P < 0.001), the elongated spermatid content of testicular parenchyma (mean, 127 x 10(6) g-1) exhibited significant seasonal variation with elevated values between February and June, suggestive of an increase in the efficiency of spermatogenesis. Daily sperm production, calculated by means of a spermatogenic time divisor for sheep, ranged from 2.76 x 10(9) in September to 7.23 x 10(9) in February. Scrotal circumference, scrotal volume and testicular length x diameter2 were identified as accurate predictors of testicular weight (R2 > or = 0.87) and sperm content (R2 > or = 0.70). The results demonstrate that: (a) cashmere bucks exhibit considerable seasonal variation in spermatogenesis associated primarily with changes in testicular mass but also with changes in the efficiency of spermatogenesis; and (b) indirect measures of testicular size are good predictors of testicular elongated sperm content. When the correct spermatogenic time divisor for goats is determined, such indirect measures may be used to predict daily sperm production.

Animals↗
PubMed1994

Calcitonin gene-related peptide reduces brain injury in a rat model of focal cerebral ischemia.

BACKGROUND AND PURPOSE: Calcitonin gene-related peptide is an endogenous vasodilating neuropeptide with a dense concentration in the trigeminocerebrovascular system. It is hypothesized that depletion of this peptide contributes to delayed cerebral ischemia after subarachnoid hemorrhage and that an exogenous supply of calcitonin gene-related peptide will augment ischemic cerebral blood flow and reduce neuronal injury. METHODS: In this study we have investigated the effect of an intravenous infusion of calcitonin gene-related peptide (100 ng/kg per minute), started 1 hour before and continued throughout 4 hours of focal cerebral ischemia, on cerebral blood flow and the volume of brain injury in a rat model of middle cerebral artery occlusion. RESULTS: Calcitonin gene-related peptide produces a significant improvement in ischemic cerebral blood flow (32 +/- 2 compared with 13 +/- 2 mL/100 g per minute in the controls; t = 6.92, P < .0001) with a concomitant reduction in the volume of ischemic brain injury (102 +/- 22 compared with 234 +/- 19 mm3; t = 4.47, P < .001). CONCLUSIONS: These findings lend support for the potential use of this peptide in the prophylactic treatment of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage.

Animals↗
PubMed1994

Subgaleal haematoma resulting in extradural compression following craniotomy. Report of two cases.

We describe two patients who underwent intracranial aneurysm surgery and developed postoperative subgaleal haematomas which, in the presence of an unfixed bone flap, resulted in significant extradural compression and a marked clinical deterioration. The application of a pressure dressing to tamponade a developing scalp haematoma is unwise unless the bone flap has been rigidly fixed in place.

Adult↗
PubMed1994

Multiple dural metastases from a pituitary adenoma. Case report.

Only 12 cases of pituitary tumors that metastasized within the central nervous system have been reported. A further case is presented in which the histology of the multiple dural metastases remained identical to that of the original tumor, a pituitary adenoma. The authors discuss management of these rare lesions that appear histologically benign.

Adenoma↗
PubMed1994

(R)-2-[4-(quinolin-2-yl-methoxy)phenyl]-2-cyclopentyl] acetic acid (BAY x1005), a potent leukotriene synthesis inhibitor: effects on anti-IgE challenge in human airways.

Anti-IgE at a fixed dilution (1:1000) contracted human airways that had been pretreated with atropine (1 microM), indomethacin (3 microM) and chlorpheniramine (1 microM). This response was blocked by the potent leukotriene synthesis inhibitor BAY x 1005 ((R)-2-[4-(Quinolin-2-yl-methoxy)phenyl)-2-cyclopentyl acetic acid]. The leukotriene synthesis inhibitor MK-886 also blocked the contraction, but BAY x1005 was approximately 10-fold more potent than MK-886 (the IC50 values were 0.27 microM and 3.4 microM for BAY x1005 and MK-886, respectively). BAY x1005 (1 microM) did not alter LTD4 cumulative concentration-effect curves on human airways. Bronchial muscles derived from different levels of the respiratory tract released small quantities of LTE4 (proximal, 7.99 +/- 1.25 ng/g tissue wet wt.; distal, 13.12 +/- 4.46 ng/g tissue wet wt.). These basal levels were significantly increased when the preparations were challenged with a fixed dilution (1:1000) of anti-IgE (proximal, 21.84 +/- 5.33 ng/g tissue wet wt.; distal 72.13 +/- 30.70 ng/g tissue wet wt.). Indomethacin (3 microM) did not alter either the basal amounts or the levels of LTE4 measured during anti-IgE stimulation. However, BAY x1005 or MK-886 in the presence of indomethacin prevented the increase in LTE4 levels that were observed during anti-IgE challenge. In these protocols the IC50 values obtained were 0.18 microM and 1.42 microM for BAY x1005 and MK-886, respectively. These data demonstrate that BAY x1005 is a potent leukotriene synthesis inhibitor in human airways.

Bronchi↗
PubMed1993

Midline aneurysms of the vertebrobasilar junction: an effective anterior approach.

There are acknowledged difficulties associated with operations on midline aneurysms at the vertebrobasilar junction. This report describes a series of such aneurysms treated by an anterior approach using a Le Fort maxillotomy to gain access via the clivus to the aneurysm. In each case the aneurysm was dealt with satisfactorily with no long-term morbidity or mortality. Attention is directed to the necessity for a water-tight dural seal postoperatively. We advocate wider use of this technique in appropriate circumstances.

Adult↗
PubMed1992

Acute treatment of alcohol and cocaine emergencies.

This chapter addresses the acute treatment of alcohol and cocaine. Because of the widespread use of both these drugs, health professionals must recognize the medical complications of alcohol and cocaine abuse and addiction. The biochemistry will be briefly reviewed as an avenue to understand the different treatment targets and modalities.

Alcoholism↗
PubMed1992

CSF drainage in patients with posterior fossa tumours.

The management of hydrocephalus secondary to a posterior fossa tumour is controversial. We audited recent practice with a retrospective analysis of 287 consecutive patients undergoing posterior fossa exploration for tumour. 85 shunts and 112 external ventricular drains (EVD) were placed. The overall CNS infection rate in the series was 6%. There was a significantly higher (p less than 0.01) infection rate in patients who had a drainage procedure, and a trend towards higher infection rates in patients with two drainage procedures. Early infection rates with EVDs and shunts were the same (7%). One third of patients with hydrocephalus had pre-operative drainage, a third had per-operative drainage but only a quarter required a permanent shunt. The majority of patients will not require a permanent shunt and where temporary CSF diversion is required EVD is reasonable.

Adolescent↗
PubMed1991

P2 specific lymphocyte transformation in Guillain-Barré syndrome and chronic idiopathic demyelinating polyradiculoneuropathy.

Thymidine incorporation proliferation assays to whole bovine P2 protein and its 58-81 and 14-25 synthetic peptides were performed on blood mononuclear cells from ten patients with Guillain-Barré syndrome (GBS), six patients with chronic idiopathic demyelinating polyradiculoneuropathy (CIDP), and age and sex matched normal subjects. The only patients whose cells showed any response were two out of four with very early GBS. One responded to P2 and both synthetic peptides. One responded to P2 but to neither peptide. The results support a role for cell mediated immunity to P2 protein in some patients with Guillain-Barré syndrome.

Adult↗
PubMed1990

T cell activation in Guillain-Barré syndrome and in MS: elevated serum levels of soluble IL-2 receptors.

Guillain-Barré syndrome (GBS), chronic idiopathic demyelinating polyradiculoneuropathy (CIDP), and multiple sclerosis (MS) are disorders with presumed immunopathogenesis. To obtain evidence for T cell activation, we determined serum concentrations of soluble interleukin-2 receptors (sIL-2 R) in 50 patients with GBS, 24 with CIDP, and 54 with MS. Both in GBS and clinically active MS sIL-2 R levels were markedly increased compared with those in patients with other neurologic diseases. Four of 24 CIDP patients had abnormally increased sIL-2 R concentrations. sIL-2 R concentrations decreased with clinical improvement in serial samples taken from GBS patients, but were not otherwise correlated with disease severity. These data establish that T cells are activated in GBS and some patients with CIDP, and corroborate earlier evidence that activated T cells are circulating in the blood of MS patients.

Chronic Disease↗
PubMed1990

Pharmacologic approaches to the treatment of cocaine dependence.

When pharmacologic agents are considered in the treatment of cocaine addiction, the objective of such treatment--sustained abstinence--must be considered. Medication and medical approaches have been disappointing in the treatment of cocaine overdose. The central neurobiologic mechanism(s) involved in cocaine toxicity are poorly understood. Without a cocaine antagonist, pharmacologic approaches have been less than promising in preventing relapse. Various psychoactive medications have been tried in early cocaine abstinence, with some success.

Amantadine↗
PubMed1989

Gamma-linolenic acid for attention-deficit hyperactivity disorder: placebo-controlled comparison to D-amphetamine.

In a Latin-square double-crossover with random assignment to sequence, 18 boys, aged 6-12 years, with attention-deficit hyperactivity disorder received 1 month each of placebo, D-amphetamine, and Efamol (evening primrose oil containing gamma-linolenic acid, with vitamin E as preservative). Parents' ratings were noncontributory. Teachers' ratings showed a trend of Efamol effect between placebo and D-amphetamine. The trend reached significance (p less than 0.05) only on Conners Hyperactivity Factor. Dosage may be crucial; 8 Efamol capsules per day were used in this study. Heuristic data scrutiny suggested possible interaction (sequence effect). Further study with a different design and dose is suggested. This study does not establish Efamol as an effective treatment.

Attention Deficit Disorder with Hyperactivity↗
PubMed1989

High-dose methylprednisolone suppresses experimental allergic neuritis in the Lewis rat.

High dose methylprednisolone (50 mg kg-1, daily) was administered to Lewis rats with experimental allergic neuritis from onset of the disease. Disease severity was reduced and recovery was significantly more rapid than that in saline-injected controls. Histological examination showed reduction of endoneurial edema, cellular infiltration, and demyelination. The results provide experimental evidence supporting the trial of high dose steroids in human demyelinating polyradiculoneuropathy.

Animals↗