Aspiration Of Cortex Research Articles

Expression of molecules associated with neuronal plasticity in the striatum after aspiration and thermocoagulatory lesions of the cerebral cortex in adult rats

Like the hippocampus, the striatum receives excitatory afferents from the cerebral cortex but, in the case of the striatum, very little is known about the molecular events associated with plasticity after lesions of this pathway. Using immunohistochemical techniques, we have examined the effects of cortical lesions induced either by aspiration of the frontoparietal cortex or by thermocoagulation of pial blood vessels on axonal and glial molecules associated with neuronal plasticity in the striatum. The growth associated protein GAP-43, a molecule present in axons and growth cones, decreased in the dorsolateral striatum after aspiration but not after thermocoagulatory lesions. In contrast, synaptophysin, a marker of synaptic vesicles, remained unchanged in the denervated striatum after both types of lesions. Immunostaining for basic fibroblast growth factor (bFGF) markedly decreased in striatal astrocytes after both lesions, despite an increased staining for glial fibrillary acidic protein (GFAP). The adhesion molecules tenascin, chondroitin sulfate proteoglycans, highly polysialylated neural cell adhesion molecule (PSA-NCAM), and laminin did not change significantly in the gray matter of the dorsolateral striatum after either type of lesion. These effects differed from those observed after partial denervation of the hippocampus and spinal cord, revealing marked regional differences in the response of axonal and glial proteins to afferent lesions. In addition, the results further indicate that cortical lesions have both similar and distinct consequences, depending on the procedure by which the lesions are induced, suggesting that cortical lesions associated with different types of pathology may differentially affect subcortical structures.

Fetal neocortical transplants grafted into neocortical lesion cavities made in newborn rats: an analysis of transplant integration with the host brain.

Fetal neocortical transplants placed into frontal cortex aspiration lesion cavities in newborn rats have been shown to survive and exchange connections with the host brain. To further study the afferent innervation of such transplants, enzyme- and immunohistochemical techniques were employed to examine the distribution of cholinergic, catecholaminergic and serotonergic fibers within the transplants, and radiochemical enzyme assays and high performance liquid chromatography were used to determine the content of neurotransmitter markers for these same fiber systems. To examine functional integration of the transplanted neurons in terms of activation of molecular signaling systems, the graft recipient animals were exposed to a novel open field environment. This behavioral testing paradigm is known to induce c-fos mRNA and Fos protein within several areas of the normal brain, including the sensorimotor cortex. Subsequent detection of the induction of this particular immediate early gene (transcription as well as translation) in the grafts would gene (transcription as well as translation) in the grafts would accordingly indicate genomic activation and therefore functional integration at the level of molecular signaling systems. Our results showed that these global fiber systems are distributed evenly throughout the extent of three mo old neocortical grafts and that the content of transmitter-related markers for these systems do not differ significantly from control cortex. Open field exposure of the grafted animals resulted in c-fos mRNA and Fos protein expression of cells distributed throughout the transplants. We conclude that the "global" fiber system innervation of neocortical transplants placed into newborn rats is similar to the innervation of normal cortex and that grafted neurons respond to host brain activation at the level of molecular signaling systems.

Fetal neocortical transplants grafted into neocortical lesion cavities made in newborn rats: An analysis of transplant integration with the host brain

Fetal neocortical transplants placed into frontal cortex aspiration lesion cavities in newborn rats have been shown to survive and exchange connections with the host brain. To further study the afferent innervation of such transplants, enzyme- and immunohistochemical techniques were employed to examine the distribution of cholinergic, catecholaminergic and serotonergic fibers within the transplants, and radiochemical enzyme assays and high performance liquid chromatography were used to determine the content of neurotransmitter markers for these same fiber systems. To examine functional integration of the transplanted neurons in terms of activation of molecular signaling systems, the graft recipient animals were exposed to a novel open field environment. This behavioral testing paradigm is known to induce c-fos mRNA and Fos protein within several areas of the normal brain, including the sensorimotor cortex. Subsequent detection of the induction of this particular immediate early gene (transcription as well as translation) in the grafts would accordingly indicate genomic activation and therefore functional integration at the level of molecular signaling systems. Our results showed that these global fiber systems are distributed evenly throughout the extent of three mo old neocortical grafts and that the content of transmitter-related markers for these systems do not differ significantly from control cortex. Open field exposure of the grafted animals resulted in c-fos mRNA and Fos protein expression of cells distributed throughout the transplants. We conclude that the “global” fiber system innervation of neocortical transplants placed into newborn rats is similar to the innervation of normal cortex and that grafted neurons respond to host brain activation at the level of molecular signaling systems.

Learning Phacoemulsification; The Incidence of Complications and the Outcome in These Cases

OBJECTIVE: To establish the incidence of surgical complications during the process of converting to phacoemulsification, to identify the stage at which complications occurred and to assess the visual outcome of complicated cases. STUDY DESIGN: A one year prospective assessment of all the phacoemulsification cases performed by 10 experienced extracapsular surgeons converting to phacoemulsification. Mean follow of cases was 5.7 months. SETTING: An Ophthalmology Department contained within a UK District General Hospital. PATIENTS: 360 consecutive phacoemulsification cataract extraction cases. MAIN OUTCOME MEASURES: Surgical complications: The occurrence during surgery of zonular dialysis, posterior capsule rupture or vitreous loss. Stage of complication: surgical manoeuvre causing posterior capsule rupture. Visual outcome: Final postoperative visual acuity. RESULTS: Thirty-three (9.2%) of phacoemulsification cases suffered surgical complications. Zonular dialysis occurred in two (0.6%) cases, posterior capsule rupture in 31 (8.6%) cases and vitreous loss in 15 (4.2%) cases. Posterior capsule rupture occurred most commonly during aspiration of lens cortex. A final postoperative acuity of at least 6/12 was attained by all complicated cases with 71.9% achieving at least 6/9. CONCLUSION: The process of converting to phacoemulsification appears to involve a relatively high incidence of surgical complications. Nevertheless, complicated cases often have a favourable visual outcome.

Irrigation, aspiration, and polishing cannula

Aspiration of the lens cortex and capsule polishing are two important aspects of modern extracapsular cataract surgery. In this report we describe simple but useful modifications to the widely used Simcoe irrigation/aspiration cannula. The modifications consist of enlarging the aspiration port diameter from 0.3 mm to 0.4 mm and altering the terminal segment of the cannula to a sandblasted capsule polisher. The 0.4 mm diameter aspiration port reduces the incidence of capsular entrapment and allows a more efficient aspiration of cortex of varying textures. The modifications eliminate the need for a separate capsule polishing instrument and allow simultaneous lens material aspiration and capsular cleanup. These modifications can be used for any irrigation /aspiration cannula whether manually or machine operated.

Effects of a Ginkgo biloba extract on two models of cortical hemiplegia in rats

To screen drugs potentially useful in the pharmacological treatment of subjects with brain lesions, we studied the effects of chronic (7 and 30 days) treatments with a Ginkgo biloba extract (EGb761-IPSEN; EGb) in two animal models of cortical hemiplegia: one induced by motor cortex aspiration and another using a reversible inactivation of the motor cortex through chronic, localized infusion of y-aminobutyric acid (GABA), via osmotic minipumps. The elevated beam test was used in water-deprived animals trained to drink saccharin-sweetened solutions (with or without EGb) and to perform to criteria before the surgical procedures. From the day after surgery, the rats were administered 100 mg/kg of EGb daily for 7 or 30 days. In all groups with motor impairment in which the extract was administered, a faster and more complete recovery was observed, which was significantly different from that of rats which received only saccharin solutions. The salutary effect of EGb was more marked in ablation-induced hemiplegia than in the GABA-treated group. In the former injury model, EGb-treated animals had smaller ventricular diameters than non-treated rats. No differences concerning sensory deficits were detected among groups. EGb was also acutely administered during the epileptic syndrome that follows interruption of chronic GABA infusions (the GABA-withdrawal syndrome). No anticonvulsant effects of EGb were observed. These results suggest a potential use of EGb in brain-injured patients as this product shows little toxicity in animals and man after chronic administration. The active principles among terpenes (ginkgolides, bilobalides and flavonolheterosides present in the EGb) and the mechanisms for this beneficial effects remain to be elucidated.

Capsulorhexis—A 5-Year Experience

Capsular surgery has now been refined with the technique of Capsulorhexis. The jagged edges of the can-opener capsulotomy technique with its attendant disadvantages is fully overcome by the smooth edged continuous tear technique of Capsulorhexis. The intact, stretchable edge allows unparalleled ease of cortex aspiration as well as certainty of in-the-bag IOL implantation. The advantages of new circular implants can also be fully realized with the anatomically undistorted bag. Although seemingly difficult to perform, the technique can be learned with no undue risk, and can be satisfactorily executed in 99.5% of cases. The integrity of the edge can also be maintained by current techniques of hydrodissection of the nucleus as well as phaco-emulsification. The author's 5-year experience is outlined.

Prefrontal cortex aspiration in pups and juvenile rats: behavioural changes and recovery of function

Male Wistar rats sustaining prefrontal cortex aspiration or sham operation at 6 days or 30 days of age were submitted to the following behavioural tests: open-field, acquisition and retention of two-way active as well as passive avoidance tasks. In the open-field the locomotor activity proved enhanced in all the aspirated animals and this enhancement lasted for 30 days. In the two-day active avoidance task, an acquisition deficit was observed in both aspirated groups; but when retrained one month later, they were able to acquire the avoidance task like sham-operated rats and no difference appeared between the groups aspirated at 6 or at 30 days of age. Concerning the passive avoidance task, no difference could be detected between aspirated and sham-operated animals of both groups except that the rats aspirated at an early age (6 days) seemed to display a better avoidance ability in the retention test. These behavioural alterations (hyperactivity and impairment of the acquisition of the 2-way active avoidance) resulted from the prefrontal cortex aspiration, at whatever age this aspiration was performed (6 days or 30 days). They disappeared after a postoperative recovery period of about one month, as evidenced by this longitudinal study.

Contributions of cingulate cortex to two forms of spatial learning and memory

The contribution of anterior and posterior cingulate cortical areas to spatial learning and memory was examined in 4 experiments using the place-navigation task. Rats with complete bilateral cingulate cortex aspiration or aspiration of posterior cingulate cortex (area 29) alone could not swim directly to a hidden platform located in a fixed place. When animals with these lesions were tested for 40 d in a place-alternation task in which they received 16 daily trials with the platform placed in a new location each day, they did not show reliable improvement in place navigation. The inability to swim to changing locations or to a single location was not overcome by preoperative training in these tasks. Rats with anterior cingulate cortex aspirations showed a less severe impairment in both tasks and, with more training than is necessary for control rats, they acquired near-normal place-navigation accuracy. Rats with complete cingulate cortex aspiration were almost as accurate as control rats in learning to swim to a visible platform. The results imply that posterior cingulate areas play an essential role in the use of topographical information, probably by transmitting and elaborating information passing between the hippocampal system and neocortical association areas.

The Choice of a Syringe For Manual Cortex Aspiration

The friction force of 5-ml, 2-ml, and 1-ml syringes used for manual aspiration of cortex material in extracapsular cataract extraction (ECCE) were compared. It was found that for a 5-ml syringe the force was 500 g, for a 2-ml syringe it was 250 g, and for a 1-ml tuberculin-type syringe it was only 50 g. The ease and duration of cortex aspiration in 30 cases of ECCE were compared using each of the above syringes partially filled with fluid, connected to a 25-gauge Gill's type cannula, and a closed anterior chamber technique. It was found that with the help of a 1-ml tuberculin syringe, cortex material was removed faster and with less finger fatigue than with the 5-ml or 2-ml syringe.

An irrigating instrument for inserting Simcoe and Binkhorst retropupillary lenses

One of the chief drawbacks to the Simcoe and new Binkhorst retropupillary lenses is the difficulty some surgeons have inserting them into the capsular bag. The fenestrations in the Simcoe are used to collapse the superior loop against the during insertion, and then to rotate (or dial) the after insertion. These fenestrations present a definite optical defect, which may cause flare and visual problems in sensitive people after surgery. They almost always cause some visual problems if the becomes decentered. The Binkhorst does not have this design defect, but it requires a great deal of training to learn to insert it properly into the bag with forceps. I have designed an instrument, the lens shooter (Figure 1), that can be used to insert either into the bag, or in front of it, and does not depend on positioning fenestrations or special loop designs. This instrument has also been used successfully with easier-toimplant lenses, such as the Intermedics model 52 modified C-Ioop. The instrument rotates the into the most desirable position. The coaxial needle used for irrigation/ aspiration of cortex is modified to present an open end at the center of the cannula. The outer irrigation cannula is not changed. A stainless steel plunger is inserted into the central cannula, and is equipped with a stop to prevent the plunger from exiting too far at the distal end of the cannula. Just prior to insertion, one loop of the is threaded into the central blunted needle with the plunger withdrawn. A syringe containing BSS solution is attached to the plastic tubing that supplies irrigation to the outer cannula. The free lower loop is then directed into the bag below, with or without irrigation. This can be done under air, under sodium hyaluronate (Healon®), or simply with BSS solution, depending on the circumstances or the surgeon's preference. The needle system containing the loop is placed just behind the anterior capsule and iris. Irrigation is then added by the assistant surgeon using the syringe

Auditory 40-Hz responses in the guinea pig

Auditory evoked potentials in response to tone bursts repeated at a rate of 40 per second (auditory 40-Hz responses) were studied in the guinea pig. The potentials, consisting of a sequence of 40-Hz waves with a periodicity of about 25 msec, were distributed widely over the skull, and the largest potentials were recorded from the vertex (midline) and the temporal area contralateral to the stimulated ear. Administration of pentobarbital did not affect the midline response but reduced the amplitude of the contralateral response. Investigations of the effects of acute lesions demonstrated that the auditory 40-Hz responses from the contralateral temporal area were eliminated by aspiration of the contralateral cerebral cortex, whereas the responses from the midline continued to appear after bilateral aspiration of the cerebral cortex. The response from the midline was maintained after bilateral aspiration of the inferior colliculi, and the basic 40-Hz rhythm was still observed after decerebration. These data suggest different generation areas for the midline and contralateral 40-Hz responses in the guinea pig.

Middle- and long-latency auditory evoked responses recorded from the vertex of normal and chronically lesioned cats

A prolonged sequence of auditory evoked potentials with latencies ranging from 1 to 250 msec was recorded from the vertex of the awake restrained cat. This sequence was reproduceable within and across subjects and was not altered by complete neuromuscular paralysis. The effects of click rate, pentobarbital, and chronic lesions of a number of different brain areas were evaluated for each of the potentials. Vertex waves 1–5, previously shown to originate from generators in the primary auditory pathway of the brain stem, were followed by smaller and less well defined waves 6 and 7, with peak latencies in the 6–8 msec and 10–12 msec range respectively. These potentials were not abolished by fast click rates (i.e. up to 50/sec) nor by moderate levels of pentobarbital. Correlative extra- and intracranial studies indicated that wave 6 occurred in the same latency range as the medial geniculate body, pars principalis potential, and that wave 7 occurred in the same latency range as the primary ectosylvian cortical potential. The intracranial potentials showed click recovery functions and barbiturate resistance which were similar to those of waves 6 and 7, and wave 7 disappeared following aspiration of ectosylvian cortex. These data suggest that waves 6 and 7 reflec generators in medial geniculate body and ectosylvian gyrus. In contrast to the stability of potentials 1 through 7, the longer latency waves were relatively unstable. Wave A occurred in a latency range of 17–25 msec, wave B, 35–45 msec, wave C, 50–75 msec, and wave D, 150–200 msec. All of these waves showed marked amplitude fluctuations, disappeared as click rates increased to 10/sec, and were abolished by moderate levels of pentobarbital. After bilateral aspiration of middle suprasylvian gyrus, ectosylvian gyrus, or frontal lobes, wave A continued to appear. After hemispherectomy, which removed all cortex, basal ganglia and limbic lobes, wave A was not abolished and appeared enhanced in one animal. Thus, the generator system of wave A appears to be largely independent of auditory cortex and adjacent association cortex, but may be modulated by other forebrain systems. Wave C continued to appear after aspiration of suprasylvian and ectosylvian gyri and after frontal lobectomy, but disappeared after hemispherectomy. Thus, wave C reflects a generator system which differs from that of wave A, but which also appears to be largely independent of the primary geniculo-cortical auditory pathway. These data suggest the following conclusions: waves 1 through 7, which show high fidelity, rate-resistant, barbiturate-insensitive acoustic transmission, appear to reflect activation of the primary auditory system from acoustic nerve to auditory cortex. Subsequent, longer-latency vertex potentials seem to be generated through other forebrain systems which receive auditory information in parallel from the brain stem, rather than serially from the primary geniculo-cortical pathway and association cortex relays. The relevance of data in the cat model to the human vertex potentials is discussed.