Biomedical subjects
Publications and source records attributed to R S Jones.
Of new patients attending our hospital, 7.1% had injured themselves playing sport. The majority had been playing football and had sustained a soft tissue injury. Many of the patients presented late, i.e. after 24 h or longer. These patients would be best dealt with in a sports clinic, staffed by personnel with an interest in this field.
Delivery of viral particles to the brain is limited by the volume of distribution that can be obtained. Additionally, there is currently no way to non-invasively monitor the distribution of virus following delivery to the central nervous system (CNS). To examine the delivery of virus-sized particles across the blood-brain barrier (BBB), dextran coated, superparamagnetic monocrystalline iron oxide particles, with a hydrodynamic diameter of 20 +/- 4 nm, were delivered to rat brain by direct intracerebral inoculation or by osmotic BBB disruption with hypertonic mannitol. Delivery of these particles was documented by magnetic resonance (MR) imaging and, unexpectedly, neuronal uptake was demonstrated by histochemical staining. Electron microscopy (EM) confirmed iron particle delivery across the capillary basement membrane and localization within CNS parenchymal cells following administration with BBB disruption. This is the first histologic and ultrastructural documentation of the delivery of particles the size of virions across the blood-brain barrier. Additionally, these dextran-coated, iron oxide particles may be useful, in and of themselves, as vectors for diagnostic and/or therapeutic interventions directed at the CNS.
Toxic shock-like syndrome due to Streptococcus pyogenes is an unusual occurrence. Previously reported cases have been the result of focal infections with S pyogenes. We present a case in which manipulation of a colonized mucosal surface during laparoscopic tubal ligation was the presumed cause of the sepsis syndrome. Whereas other reports of this syndrome have all noted concurrent infections with S pyogenes, in this instance it was unclear if toxin-mediated disease was initiated by mild endometritis or iatrogenic manipulation of a colonized mucosal surface.
Pseudocysts represent a relatively common problem in the management of patients with pancreatic disease. In evaluating the outcome of treatment, many authors have failed to differentiate between those pseudocysts that follow an attack of acute pancreatitis and those that occur with established chronic disease. We retrospectively reviewed the outcome of treatment in 97 patients admitted to the University of Virginia Hospital in Charlottesville over a 6-year period with a diagnosis of pancreatitis pseudocyst. In 50 of the 97 patients (52%), the pancreatic pseudocyst followed an attack of acute pancreatitis, and 47 (48%) patients had chronic disease. The mean age at presentation was 48.6 +/- 16.4 years for the entire group. Twenty-four patients (25%) were black, and 73 (75%) were white. Sixty-four patients were male (66%), and 33 were female (34%). Alcohol was the important etiological agent in 30 of the 47 patients with chronic pancreatitis (64%), but only 13 of the 50 patients (26%) with acute pancreatitis. By comparison, gallstones were the precipitating cause in 13 of the 50 patients with acute pancreatitis (26%), but only 5 of the 47 patients (11%) with chronic pancreatitis. Thirty-one patients (32%) were treated by observation, 37 patients (36%) by percutaneous aspiration or drainage, and 46 patients (47%) by surgical drainage or resection. Some patients fell into more than one category. Our findings suggested that many patients with small cysts (less than 6 cm) can be managed by a period of observation.(ABSTRACT TRUNCATED AT 250 WORDS)
Ultrasound is widely advocated as the initial noninvasive imaging study in evaluating suspected biliary obstruction. Some have suggested using ultrasound as the sole diagnostic test before exploratory laparotomy. To evaluate the accuracy of ultrasound in determining the level and etiology of biliary obstruction in patients with biliary dilatation, and to define its role in the evaluation of these patients, we performed a retrospective review of all patients from August 1986 to August 1991 who had biliary dilatation by ultrasound and subsequent endoscopic retrograde cholangiopancreatography and/or a percutaneous transhepatic cholangiography. Forty-two patients were included in this study, and ultrasound delineated the level of obstruction in 88 per cent, defined the etiology of the obstruction in 48 per cent, and diagnosed choledocholithiasis in 33 per cent of patients with this condition. A literature review revealed that ultrasound has a sensitivity of 71 per cent in delineating the level of obstruction, a sensitivity of 57 per cent in defining the etiology of biliary obstruction, and detects choledocholithiasis in 32 per cent of patients with this condition. We conclude that ultrasound is a highly accurate diagnostic test for delineating the level of biliary obstruction. Ultrasound should be the initial radiographic test in the evaluation of the patient with suspected biliary obstruction to guide further radiographic evaluation.
Romifidine, 100 micrograms/kg administered by intravenous injection, was evaluated as a premedicant to ketamine/halothane anaesthesia in 60 horses. Sedation developed within one to two minutes. In three cases mild staggering occurred within two minutes. Anaesthesia was induced after five minutes by the intravenous administration of ketamine (2 to 2.2 mg/kg). A mean time of 79 seconds elapsed before lateral recumbency was adopted. Fifty-four of the horses sank smoothly to the floor, with occasional steps sideways. Jaw tone, limb rigidity and mild muscle tremors often persisted for short periods after induction. Complete relaxation was achieved on average two minutes after the administration of ketamine. The transition to oxygen/halothane anaesthesia was excellent or good in 53 cases. The mean duration of anaesthesia was 79 minutes. Forty-seven of the horses were able to stand after one or two attempts with little or no ataxia. After halothane administration ceased, the mean time to sternal recumbency was 25 minutes and the mean time to standing was 33 minutes. Most horses appeared to be sedated upon standing, but they were able to walk soon after regaining their feet. The characteristics of the induction of anaesthesia were similar to those seen when detomidine/ketamine or xylazine/ketamine are used. The maintenance of anaesthesia with halothane was similar to that following other induction protocols, and the recovery from anaesthesia was smooth and free from excitement.
We have studied the interactions between dopamine and glutamate-mediated transmission in the entorhinal cortex using intracellular recording in a slice preparation from the rat brain. High concentrations (0.1-1 mM) of dopamine had weak, direct effects on the membrane potential with predominantly hyperpolarizing responses in layer II neurons and depolarizing responses in layer V. Studies with the dopamine antagonists sulpiride (D2 antagonist, 10-50 microM) and SCH-23390 (D1 antagonist, 50 microM) indicated that the hyperpolarization by dopamine could be mediated by D2 receptors, although the pharmacology was not clear-cut. The depolarizing response was not affected by either D1 or D2 antagonists. Synaptic responses of layer II and layer V cells were complex, consisting of both inhibitory and excitatory potentials. In untreated slices, dopamine reduced all components of the synaptic responses. However, when components of the responses were pharmacologically isolated, only the excitatory, glutamate-mediated potentials were consistently affected and the GABAergic inhibitory potentials were more resistant to reduction by dopamine. Excitatory potentials mediated by both N-methyl-D-aspartate and alpha-amino-3-hydroxy-5-methyl-isoxazolepropionic acid receptors were reduced by dopamine, but the former were more strongly affected. Studies with antagonists suggested that the D1 receptor is more likely to be involved in the decrement of glutamate transmission. Thus, dopamine appears to modulate glutamate-mediated synaptic transmission in the entorhinal cortex, and it is conceivable that a disturbance in this interaction could be involved in the aetiology of schizophrenia.
Spiny stellate neurones of layer II of the entorhinal cortex (EC) provide the perforant path input to the dentate gyrus. Previous studies have shown that synaptic responses of these neurones are dominated by GABAergic inhibition. The present study describes intracellular recordings from 'fast-spiking' interneurones in layer II which may be the basis of the synaptic inhibition. Lucifer yellow fills of fast-spiking cells revealed neurones with a widespread axonal arborization forming basket-like complexes around unlabelled cells in layer II. Synaptic activation of the fast-spiking cells evoked long duration excitations which were mediated largely by NMDA receptors. A fast AMPA/kainate EPSP was also detectable. These neurones have morphological and physiological properties which make them well-suited to exert a widespread inhibitory control over the efferent output of layer II to the dentate gyrus.
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On the basis of neuroanatomical studies, the entorhinal cortex (EC) has long been regarded as a relay station that provides the major source of afferent input to the hippocampus. The perforant path input to the dentate gyrus from layer II has traditionally been regarded as the major pathway by which information is transferred. However, electrophysiological studies are now indicating that other elements of the perforant path that project directly to CA1 and CA3 are more important than thought previously, and that the properties of different neuronal elements in the EC may determine the way in which information is passed on to and processed by the hippocampus. This article summarizes some of the properties of synaptic transmission in the EC and speculates on how frequency-dependent changes in transmission may be involved in the pre- and post-processing of hippocampal information by the EC.
A fault in the assembly of a Matrix Large Animal Circle anaesthetic machine resulted in reversal of fresh gas flow through the vaporizer. The fault was discovered only after the sudden development of excessive depth of anaesthesia in two equine patients. Laboratory investigations were conducted to determine the effect of flow reversal on vaporizer output. Results indicated that output concentration was approximately doubled under these conditions.
OBJECTIVE: This experiment determined the effects of liver transplantation on bile salt kinetics and biliary lipid secretion. SUMMARY BACKGROUND DATA: Depression of bile secretion in the three main components and bile cholesterol supersaturation with a high incidence of cholesterol stone formation have been documented in patients with end stage liver diseases after transplantation. However, physiologic changes of bile salt and lipid secretion in recipients remain unclear. METHODS: The study was done using a rat liver transplant model with 1 and 6 hours of donor liver cold preservation in saline. A chronic common bile duct fistula and a duodenal cannula were established for bile collection and the sample biochemical study for 6 days. RESULTS: Altered bile salt kinetics in liver grafted rats included depressed bile flow for 1-3 hours after the revascularization, decreased bile salt concentration and outputs, reduced bile salt basal synthesis rate, and reduced bile salt pool size during the early postoperative period. Phospholipid concentration and secretion rate depressed for 1-3 days without altered cholesterol level. The uncoupling change of the cholesterol and the other bile components resulted in an increased lithogenic indices in bile on days 2 and 3. CONCLUSION: Alterations of bile composition and bile salt kinetics occur in liver transplanted rats. The changes may result from injuries of the liver microcirculation and parenchymal cells caused by cold preservation. The study of bile secretion is helpful for evaluation of the initial graft function. The changed ratio of three bile components may be important for cholesterol stone formation in the liver transplant recipient.
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OBJECTIVE: The purpose of this research was to study the correlation between bile secretion and the liver regeneration in the partially hepatectomized rat. SUMMARY BACKGROUND DATA: Significant alteration in bile formation and secretion is expected in the liver after hepatectomy. There is scant literature, however, about the effects of liver regeneration in bile secretion. METHODS: The work was done in rats with 50% hepatectomy, 75% hepatectomy, and sham operation as the control. A chronic common bile duct fistula and a duodenal cannula were established for bile collection and the sample analysis on days 1, 3, 5, 7, and 9. RESULTS: With size reduced in the liver after 50% and 75% hepatectomy, the total bile volume decreased 45.9% and 51.5%, bile salt independent flow decreased 59.3% and 64.9%, bile salt secretion rate decreased 36.1% and 43.4%, bile salt basal synthesis rate decreased 52.3% and 56.4%, phospholipid secretion rate decreased 52.6% and 68.0%, and cholesterol secretion rate decreased 54.3% and 72.4% from control on day 1, respectively. All changes returned to the control level in 3 to 9 days with accompanying increasing liver size during regeneration. CONCLUSION: Alterations of total bile flow, bile salt independent flow, bile salt secretion rate, bile salt basal synthesis rate, and biliary lipid secretion after partial hepatectomy correlate with the liver regeneration rate in rats. Partial hepatectomy reduces the bile salt independent fraction calculated as per 100 g body weight rather than the dependent fraction. The study of bile salt and biliary lipid secretion is a useful method for monitoring synthetic function in liver regeneration in vivo.
General anaesthesia was maintained in 40 horses by the continuous intravenous infusion of a mixture of 500 ml 10% guaifenesin solution, 1 g ketamine and 500 mg xylazine. The median duration of infusion was 65 mins (interquartile range 51-95 mins). Anaesthesia was characterised by active palpebral reflexes, variable degrees of nystagmus and occasional swallowing. Swallowing was considered to be undesirable in horses undergoing laryngeal surgery, but the infusion produced satisfactory conditions for all other surgical procedures performed. Arterial blood pressure was well maintained in all cases (median mean arterial blood pressure = 85 mmHg after 30 mins anaesthesia). Heart rate and PaCO2 were significantly lower, whilst PaO2 was significantly higher in the infusion group than in a group of paired control horses which were anaesthetised with halothane. Recovery from anaesthesia was good (Grades 1-2) in 33 horses. Median times to sternal recumbency and to standing were 24 and 38 mins respectively. The infusion caused a significant fall in packed cell volume, haemoglobin concentration and red blood cell count (P < 0.01) and a significant rise in plasma glucose concentration (P < 0.01). These variables returned to pre-infusion values within 24 h.
Assembly of type C retroviruses such as Moloney murine leukemia virus (M-MuLV) ordinarily occurs at the plasma membranes of infected cells and absolutely requires the particle core precursor protein, Pr65gag. Previously we have shown that Pr65gag is membrane associated and that at least a portion of intracellular Pr65gag protein appears to be routed to the plasma membrane by a vesicular transport pathway. Here we show that intracellular particle formation can occur in M-MuLV-infected cells. M-MuLV immature particles were observed by electron microscopy budding into and within rough endoplasmic reticulum, Golgi, and vacuolar compartments. Biochemical fractionation studies indicated that intracellular Pr65gag was present in nonionic detergent-resistant complexes of greater than 150S. Additionally, viral RNA and polymerase functions appeared to be associated with intracellular particles, as were Gag-beta-galactosidase fusion proteins which have the capacity to be incorporated into virions. Immature intracellular particles in postnuclear lysates could be proteolytically processed in vitro to mature forms, while extracellular immature M-MuLV particles remained immature as long as 10 h during incubations. The occurrence of M-MuLV-derived intracellular particles demonstrates that Pr65gag can associate with intracellular membranes and indicates that if a plasma membrane Pr65gag receptor exists, it also can be found in other membrane compartments. These results support the hypothesis that intracellular particles may serve as a virus reservoir during in vivo infections.
As is typical of Polycomb-group loci, the Enhancer of zeste [E(z)] gene negatively regulates the segment identity genes of the Antennapedia (ANT-C) and Bithorax (BX-C) gene complexes. A second class of loci, collectively known as the trithorax group, plays an antagonistic role as positive regulators of the ANT-C and BX-C genes. Molecular analysis of the E(z) gene predicts a 760-amino-acid protein product. A region of 116 amino acids near the E(z) carboxy terminus is 41.2% identical (68.4% similar) with a carboxy-terminal region of the trithorax protein. This portion of the trithorax protein is part of a larger region previously shown to share extensive homology with a human protein (ALL-1/Hrx) that is implicated in acute leukemias. Over this same 116 amino acids, E(z) and ALL-1/Hrx are 43.9% identical (68.4% similar). Otherwise, E(z) is not significantly similar to any previously described proteins. As this region of sequence similarity is shared by two proteins with antagonistic functions, we suggest that it may comprise a domain that interacts with a common target, either nucleic acid or protein. Opposite effects on transcription might then be determined by other portions of the two proteins.
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