Effect of lidocaine after experimental cerebral ischemia induced by air embolism

To investigate possible approaches to the treatment of neural damage induced by air embolism and other forms of acute cerebral ischemia, somatosensory evoked potentials (SEP's) were measured after cerebral air embolism in the anesthetized cat. Air was introduced into the carotid artery in increments of 0.08 ml until the SEP amplitude was reduced to approximately 10% or less of baseline values. Either a saline or lidocaine infusion was begun 5 minutes after inducing cerebral ischemia. In the saline-treated group, SEP amplitude was reduced to 6.7% +/- 1.6% (mean +/- standard error of the mean) of baseline, with a return to 32.6% +/- 4.7% of baseline over a 2-hour period. In the lidocaine-treated group, SEP amplitude was reduced to 5.9% +/- 1.5%, with a return to 77.3% +/- 6.2% over a 2-hour period. The results suggest that lidocaine administration facilitates the return of neural function after acute cerebral ischemia induced by air embolism.

The calmodulin-stimulated ATPase of maize coleoptiles is a 140000-Mr polypeptide

The calmodulin-stimulated ATPase of maize (Zea mays L.) coleoptiles has been purified by calcium-dependent binding to a calmodulin affinity column. In the presence of protease inhibitors (phenylmethylsulfonylfluoride and chymostatin) a polypeptide of relative molecular mass (Mr) 140000 (±10000) is obtained on sodium-dodecylsulphate polyacrylamide gels. This polypeptide is recognised specifically by an affinity-purified polyclonal antibody to mammalian calmodulin-stimulated calcium-pumping ATPases and is of similar Mr to the erythrocyte-membrane calcium pump (138000 Mr).

Correlations between gametophytic (pollen) and sporophytic (seed) generations for polyunsaturated fatty acids in oilseed rape Brassica napus L

Lipids were extracted from the diploid seed and haploid pollen of Brassica napus L. Two fractions of pollen lipids, namely the diploid-specified pollen-coat and the haploid-specified internal cytoplasmic lipids were obtained. Significant correlations exist between pollen and seed generations for linoleic (18∶2) and linolenic (18∶3) acids. In pollen internal storage lipids, the level of 18∶3 is positively correlated and the level of 18∶2 is negatively correlated with the level of 18∶3 in seed lipids. Evidence is presented that strongly supports the hypothesis that lipid biosynthesis occurs within the pollen and that synthesis is specified by haploid genes. These data support the concept of pollen selection, so that selecting among living pollen grains for superior individuals has potential as a new plant breeding tool for improving seed oil quality.

Calcium transport by pea root membranes : I. Purification of membranes and characteristics of uptake

Calcium transport has been studied using purified endomembrane vesicles from dark-grown roots of Pisum sativum L. Membranes from a mixed microsomal (non-mitochondrial) fraction showed ATP-dependent calcium uptake which was released by the ionophore A 23187, had a pH optimum of 7.2 and required Mg(2+) for uptake. Membranes were further purified using a rapid sucrosedensity-gradient technique yielding vesicles suitable for transport studies, and were identified using marker enzymes. Uptake by plasma membrane, tonoplast, endoplasmic reticulum and Golgi apparatus was indicated. Uptake by membranes of low density (predominantly tonoplast) had a pH optimum of 7.2-7.4 and nucleotide specificity ATP> guanosine 5'-triphosphate>inosine 5'-triphosphate>ADP>, while that by high-density membranes had a pH optimum of 7.5-7.9 and less specificity for ATP. The importance of regulating sucrose concentrations in calcium transport studies was demonstrated.

Calcium transport by pea root membranes : II. Effects of calmodulin and inhibitors

Calcium transport by purified endomembrane vesicles from roots of Pisum sativum L. was studied. Two types of ATP-dependent transport were demonstrated, protonophore-sensitive calcium/proton antiport and protonophore-insensitive transport. The former was predominantly located in the tonoplast, while the latter was associated with the plasma membrane and Golgi apparatus. Calcium uptake by membranes of low buoyant density (tonoplast) was inhibited by nitrate and was not sensitive to sodium orthovanadate while that by membranes of high buoyant density (plasma membrane, Golgi apparatus) was inhibited by sodium orthovanadate and insensitive to nitrate. Endoplasmic reticulum also took up calcium in the presence of ATP; however, because of its imperfect separation from the tonoplast, the nature of the calcium-transport system present could not be fully characterised. None of the calcium transporters were stimulated by calmodulin or inhibited by calmodulin inhibitors.

Antibodies to brain clathrin recognise plant coated vesicles

Coated vesicles isolated from carrot suspension culture cells were immune-blotted against four antibodies to porcine brain clathrin. Positive cross-reaction was obtained with three antibodies. Two of these cross-reacted with both the heavy clathrin chain and the putative light chains. Three out of five antibodies immunofluorescently stained permeabilised carrot suspension culture cells.

Reduction of experimental intracranial hypertension by lidocaine

Previous animal studies in our laboratory revealed that acute cerebral ischemia induced by air embolism is accompanied by a sharp and pronounced rise in both systemic blood pressure and intracranial pressure. To investigate possible approaches to the treatment of severe intracranial hypertension, we produced cerebral air embolism in anesthetized, ventilated cats by the infusion of air into the vertebral artery. Untreated animals consistently experienced severe acute intracranial hypertension. Pretreating the animals with lidocaine greatly attenuated the intracranial hypertension caused by air embolism. Lidocaine given after the injury was also effective in reducing intracranial pressure. Our results suggest that lidocaine may be a useful agent for reducing intracranial hypertension associated with ischemic or traumatic injuries to the brain.

Blockade of neonatal activation of the pituitary-testicular axis with continuous administration of a gonadotropin-releasing hormone agonist in male rhesus monkeys

The objective of this study was to determine the effects of continuous GnRH agonist (Ag) treatment on neonatal activation of the pituitary-testicular axis in male rhesus monkeys. Five infants were treated continuously with Ag(10 micrograms/day; Wy-40972) for 112 days using osmotic minipumps beginning at 10-13 days of age. Two of five age-matched control animals were implanted sc with Silastic implants of comparable size to the minipumps; three did not receive sham implants. Ag treatment caused a fall in serum LH (bioassay) values to undetectable levels (much less than 0.1 micrograms/ml) within 3 weeks, where they remained throughout Ag treatment. Mean serum testosterone (T) levels fell from pretreatment values of 1.52 +/- 0.45 to 0.38 +/- 0.09 (+/- SE) ng/ml after 3 weeks of Ag treatment. The level of T never exceeded 0.60 ng/ml throughout the subsequent course of Ag treatment. In contrast, serum LH and T were elevated to levels that approached adult values during the first 2 postnatal months in control infants with or without sham implants. Both LH and T then gradually declined, and by 4 months of age, T levels were indistinguishable from those in Ag-treated animals. Control infants had an increase in serum LH from 0.56 +/- 0.10 to 2.67 +/- 0.49 micrograms/ml within 60 min of administration of 5 micrograms GnRH/kg BW at 60 days of age. Serum T values rose from 2.35 +/- 1.00 to 9.48 +/- 3.15 ng/ml during the same period. Seven weeks of Ag treatment abolished the LH and T responses to GnRH. Thirty days after the termination of Ag treatment (approximately 150 days of age), Ag-treated and control infants had comparable serum LH and T responses to GnRH, although the responses were reduced relative to the responses in controls at 60 days of age. These results suggest that continuous administration of Ag desensitizes the pituitary of the male infant rhesus monkey to GnRH and blocks neonatal activation of the pituitary-testicular axis.

Effect of intravenous lidocaine on experimental spinal cord injury

A series of experiments was conducted to study the effect of systemic intravenous administration of lidocaine on neurological recovery after acute experimental spinal cord injury in cats. The spinal cord was injured by the rapid inflation of an epidural balloon at T-6. The physiological integrity of the spinal cord ceased within 2 seconds in all animals, as demonstrated by acute disappearance of the somatosensory evoked response (SER). There was essentially no return of the SER in the five untreated animals when monitored for 4 hours post-injury. All of the pathological specimens from these animals revealed severe central cord hemorrhage. Intravenous lidocaine was begun 15 minutes after the injury in five animals. Three of these animals had significant return of the SER. The pathological specimens from the lidocaine-treated animals revealed either mild or moderate central cord hemorrhage. The results of this experiment suggest that systemic lidocaine administration has a significant beneficial effect in the treatment of acute spinal cord injury.

Protective effect of lidocaine in acute cerebral ischemia induced by air embolism

To investigate possible approaches to the prevention and treatment of neural damage induced by air embolism and other forms of acute cerebral ischemia, a model was used in which cerebral air embolism was produced by infusion of air (0.4 ml) into a vertebral artery of chloralose-anesthetized cats. Neurological function was assessed by measuring cortical somatosensory evoked responses in a group of 10 untreated animals and in a group of eight animals pretreated with intravenous lidocaine (5 mg/kg). In the untreated group, the primary somatosensory amplitude was reduced to 28% +/- 9% (mean +/- standard error) of the value before air embolism, with a return to 60% +/- 8% 1 hour and 73% +/- 12% 2 hours after embolism. In the group pretreated with lidocaine, the primary somatosensory amplitude was reduced to 68% +/- 9% of the value before air embolism, with a return to 92% +/- 3% 1 hour and 97 +/- 2% 2 hours after embolism. Pretreatment with lidocaine also greatly attenuated the acute hypertension and the increase in intracranial pressure following air embolism. These results demonstrate that pretreatment with intravenous lidocaine significantly reduces the neural decrement and increases the recovery of neural function after acute cerebral ischemia induced by air embolism.

Effects of hyperbaric oxygen exposure at 31.3 ATA on spontaneously beating cat hearts

Cardiovascular responses to raised ambient pressure and acute hyperbaric oxygen (HBO) exposure [HBO, partial pressure of oxygen (PO2) = 2 ATA)] were examined in anesthetized cats. Relatively normoxic [PO2 = 0.35 ATA] helium compression to 31.3 ATA decreased spontaneous heart rate, prolonged the P-R and Q-T intervals of the ECG independently of changes in rate, and significantly increased ventricular contractility. HBO while at depth produced further decreases in heart rate, with no change in the P-R interval. The Q-T interval decreased significantly in the presence of bradycardia, particularly during the first 15 min of exposure. During the first 10-15 min of HBO exposure myocardial contractility and developed ventricular pressure were reduced, but contractility increased significantly at 30 min. These results indicate that HBO interacts with depth effects to produce hyperbaric bradycardia but reverses pressure actions on ventricular repolarization. The inotropic effects of HBO are time dependent, with slightly negative effects occurring initially, followed by positive inotropic actions at 30 min.

Hyperbaric exposures alter cardiac excitation-contraction coupling

Cardiac excitation-contraction (E-C) coupling variables were measured in anesthetized cats during helium-oxygen dives to 1000 fsw (305 msw). At constant pacing rates of 190-300/min the delay between onset of ventricular excitation and onset of developed pressure increased with depth, the larger increases occurring at faster rates. The electrocardiographic Q-T interval increased with depth at all rates, but rate-related shortening of Q-T was less at depth. At a rate of 190, the indexes of contractile performance were enhanced by increases in depth, but they showed little change or were lessened at faster rates. Predive changes in contractility, time to peak pressure, and systolic duration correlated positively with rate-induced changes in the Q-T interval. The correlations were reduced or reversed at depth, however, suggesting a dissociation of E-C coupling. Several cases of conduction arrhythmias or pulsus alternans were encountered with increases in depth and heart rate. These results suggest cardiac E-C coupling is altered by interactions of depth and heart rate. Further, these findings may have relevance to the capacity of the cardiovascular system to support periods of work in a hyperbaric environment.

A study of the subcellular localisation of an ethylene binding site in developing cotyledons of Phaseolus vulgaris L. by high resolution autoradiography

Use was made of light microscopy and high resolution electron microscope autoradiography to determine the subcellular localisation of a binding site with a high affinity and specificity for ethylene in developing cotyledons of Phaseolus vulgaris L. The results indicate that the binding site is located on the endoplasmic reticulum and protein body membranes, confirming previous studies using cellular fractionation and marker enzymes.

Posterior fixation suture operation (fadenoperation)

The posterior fixation operation affords the ophthalmologist an additional procedure for the correction of DVD, nystagmus blockage syndrome and abnormal distance/near relationships associated with esodeviations. The authors report that 95% of the patients had improved their control of manifest DVD. The results of surgery for the nystagmus blockage syndrome and abnormal distance/near relationship patients remain inconclusive. The posterior fixation procedure, while technically difficult, may be performed safely by the experienced surgeon. Refinements of the surgical technique are described.

Cardiovascular effects of cerebral air embolism

This study was conducted to determine whether air distributed to the cerebral circulation alone could cause acute cardiovascular dysfunction and thus be a potential mechanism for sudden death following arterial air embolism. Cardiovascular measurements were made in anesthetized, ventilated cats during infusion of air into a vertebral artery. Cerebral air embolism was found to induce an acute hypertensive response accompanied by severe cardiac arrhythmias. Interruption of the autonomic nervous system was found to abolish the cardiac arrhythmias but not to affect significantly the acute hypertensive response following cerebral air embolism. These results suggest that potentially lethal cardiac arrhythmias can occur from air distributed solely to the cerebral circulation, and that these arrhythmias are mediated by the autonomic nervous system. The results also indicate that acute hypertension can occur from cerebral air embolism, but that this response is not solely mediated by the autonomic nervous system.

Measurement of visual acuity in latent nystagmus

A method is described for rapid and accurate assessment of visual acuity in patients with latent (occlusion) nystagmus. By using the duochrome slide of the American Optical Project-O-Chart and the green filter of the Worth red-green glasses, monocular visual acuity may be readily measured in patients with nystagmus brought out by monocular cover. The results obtained in seven patients are compared with standard opaque occlusion and occlusion with a +5.00 diopter lens.

Thermal Acclimation in Several Species of Stored-Grain Beetles

The chill-coma temperatures, oxygen consumption at several constant temperatures, and fresh weights of adults of Cryptolestes ferrugineus (Steph.), Oryzaephilus surinamensis (L.), Rhyzopertha dominica (F.) and Tribolium castaneum (Hbst.) were determined before and after acclimation for 14 days at 15 deg C in the laboratory in Australia. Acclimation lowered the mean chill-coma temperatures of all species, but most in O. surinamensis. The oxygen consumption of insects that were free to move and of insects restrained during respirometry was reduced by acclimation. The curves relating respiration rate and temperature were shifted downwards by cold acclimation, but its effect on their slopes (i.e. on temperature sensitivity) varied between and within species. Similarly, the relative proportions of the change in the consumption rates of free insects acclimated at 15 deg C that were attributable to locomotor activity or to resting metabolism varied considerably. The weights of C. ferrugineus and R. dominica were increased by cold acclimation, but those of the other 2 species were not.

Visual loss as a result of primary optic nerve neuropathy after intranasal corticosteroid injection

A 25-year-old woman experienced acute visual loss after injection of methylprednisolone suspension into the concha nasalis inferioris. Results of ophthalmoscopic examinations were normal throughout the observation period, a finding not reported previously in cases of visual loss after head or neck injections. An afferent pupillary defect, which diminished as visual acuity improved, implicated otpic nerve damage, as did the visual field defect which also improved slightly. This is, to our knowledge, the first case report of acute visual loss caused by optic nerve neuropathy after injection to the head or neck.

Effects of progressive hypoxia on long tract neural conduction in the spinal cord

In this experiment, the vulnerability of long tract neural conduction in the spinal cord to progressive hypoxia was studied. The physiological integrity of nonsynaptic spinal cord conduction was monitored with the spinal evoked response (SER). Focal spinal cord blood flow was measured with the hydrogen clearance method. Progressive hypoxia was created by progressively increasing the amount of nitrogen in the inspired gas mixture. The SER was seen to fail only after extended periods of severe hypoxia. Multisynaptic cerebral condition monitored by the cerebral evoked response (CER) seemed more sensitive in the three animals in which both SER and CER were recorded. Spinal cord blood flow (SCBF) was not affected by progressive hypoxia until the PO2 was below 40 torr, and then the SCBF rose dramatically with further progression of the hypoxia.

Studies on ethylene binding by cell free preparations from cotyledons of Phaseolus vulgaris L. : II. Effects of structural analogues of ethylene and of inhibitors

Various protein reactive agents such as dithioerythritol, dithiothreitol, mercaptoethanol and p-chloromercuribenzoate inhibit binding of ethylene to cell free preparations of Phaseolus vulgaris L. The effect of the thiols is partially reversed by treatment with diamide; occupation of the binding site by ligand diminishes the inhibition caused by p-chloromercuribenzoate but not that caused by thiols. Growth regulators other than ethylene do not affect binding. Physiologically active structural analogues of ethylene competitively inhibit binding of the growth regulator and their relative effectiveness in the cell free system closely resembles that in developmental processes controlled ethylene.

Studies on ethylene binding by cell-free preparations from cotyledons of Phaseolus vulgaris L. : I. Separation and characterisation

The preparation is described of a cell-free system from developing cotyledons of Phaseolus vulgaris cv. Canadian Wonder which is capable of binding ethylene. The binding is saturable and the apparent dissociation constant for ethylene is 6.4·10(-10) M in solution. The binding site is associated with subcellular particles and treatment with Triton X-100 results in substantial solubilisation of the activity. The kinetics of association and dissociation of the ligand and the binding site are described. The system is heat labile and binding activity is diminished by treatment with some proteolytic enzymes.