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Biomedical subjects

A Jackowski

Publications and source records attributed to A Jackowski.

27 records · Page 2Linked to original sources
PubMed1991

Surgical treatment of pontomedullary cavernomas.

Direct treatment of brainstem cavernous haemangiomas (cavernomas) naturally represents a considerable surgical challenge due to the close proximity of vital structures. The results of such treatment have only rarely been described. We report our experience in the management of seven patients with cavernomas of the brainstem treated by microsurgical resection. All patients presented with neurological symptoms directly attributable to one or more episodes of brainstem haemorrhage. CT scan examination in all cases revealed either obvious haematoma or a focal region of high density within the pons or medulla; calcification in and around the lesion was detected in two patients. MRI scanning was performed in four of our cases and was strongly suggestive of the diagnosis of cavernoma with evidence of both recent and older haemorrhage as evidenced by haemosiderin deposits. Cerebral angiography failed to disclose abnormal vessels to the cavernoma in any instance, although interestingly a co-existent but separate cerebellar venous malformation was observed in two of our cases. Surgery was performed between 19 days and 3 months following the most recent haemorrhage. Microsurgical removal of both haematoma and underlying cavernoma was accomplished either via a median suboccipital or retromastoid craniectomy, with an appropriate incision being made into that part of the brainstem most directly overlaying the lesion. Significant improvement in neurological function has followed in all seven cases. Although the natural history of symptomatic cavernous haemangiomas is incompletely understood, the favourable results obtained in our patients suggest that total surgical removal is both practicable and relatively safe even in the case of those lesions situated within the brainstem.

Adult↗
PubMed1990

Epidural haematoma requiring surgical decompression following repeated cervical epidural steroid injections for chronic pain.

We report a case of epidural haematoma following a steroid injection into the cervical epidural space. The complication occurred on the seventh such injection over a 2 year period for chronic spinal pain. Surgical decompression over the seventh cervical and the upper 3 thoracic vertebrae was required to alleviate the symptoms of paralysis and anaesthesia. The patient subsequently required skin grafting to the surgical site and two trans-urethral resections of the prostate gland during his 6 week hospital admission. He made a full recovery.

Chronic Disease↗
PubMed1990

The time course of intracranial pathophysiological changes following experimental subarachnoid haemorrhage in the rat.

The rat subarachnoid haemorrhage (SAH) model was further studied to establish the precise time course of the globally reduced CBF that follows and to ascertain whether temporally related changes in cerebral perfusion pressure (CPP) and intracranial pressure (ICP) take place. Parallel ultrastructural studies were performed upon cerebral arteries and their adjacent perivascular subarachnoid spaces. SAH was induced by a single intracisternal injection of autologous arterial blood. Serial measurements of regional cortical CBF by hydrogen clearance revealed that experimental SAH resulted in an immediate 50% global reduction in cortical flows that persisted for up to 3 h post SAH. At 24 h, flows were still significantly reduced at 85% of control values (p less than 0.05), but by 48 h had regained normal values and were maintained up to 5 days post SAH. ICP rose acutely after haemorrhage to nearly 50 mm Hg with C-type pressure waves being present. ICP then fell slowly, only fully returning to control levels at 72 h. Acute hydrocephalus was observed on autopsy examination of SAH animals but not in controls. Reductions in CPP occurred post SAH, but only in the order of 15%, which could not alone account for the fall in CBF that took place. At 48 and, to a lesser extent, 24 h post SAH, myonecrosis confined largely to smooth muscle cells of the immediately subintimal media was observed. No significant changes in the intima or perivascular nerve plexus were seen. Within 24 h of haemorrhage, a limited degree of phagocytosis of erythrocytes by pial lining cells took place. However, early on the second day post SAH, a dramatic increase in the numbers of subarachnoid macrophages arose from a transformation of cells of the pia-arachnoid. This period was characterised by intense phagocytic activity, erythrocytes, fibrin, and other debris being largely cleared over the next 24 h. At 5 days post SAH the subarachnoid macrophage population declined, cells losing their mobile active features to assume a more typical pia-arachnoid cell appearance once more. Our studies indicate that this increasingly utilised small animal model of SAH develops global cortical flow changes only acutely, and it is likely that early vasospasm, secondary to released blood products rather than pressure changes per se, is responsible for the initial cerebral ischaemia that develops. Interestingly, both cerebral arterial vasculopathy and perivascular macrophage phagocytic activity are most marked at approximately 48 h following SAH in the rat, a time at which a phase of delayed cerebral arterial narrowing has previously been documented.

Animals↗
PubMed1989

Serial determinations of regional cerebral blood flow in the rat using simple chronically implanted platinum wire microelectrodes.

The ability to reliably obtain serial determinations of regional cerebral blood flow (rCBF) over time in small animals using simple and inexpensively constructed platinum-wire microelectrodes has been investigated. Repeated measurements of local cortical flow were obtained on a daily basis using the hydrogen clearance technique in a group of 18 animals, in each of which, 6 electrodes were chronically implanted. Our studies have shown the simple microelectrodes utilised to give a low variability of results, as well as being well tolerated and provoking minimal tissue reaction even over prolonged periods of time. Under identical steady-state conditions, serial determinations of rCBF were obtained for up to one week, with a maximum variation in mean values of only 12%, a result that compares favourably with the known serial determination error for the technique in the shorter term.

Animals↗
PubMed1989

5-Hydroxytryptamine demonstrated immunohistochemically in rat cerebrovascular nerves largely represents 5-hydroxytryptamine uptake into sympathetic nerve fibres.

This study has re-examined, by immunohistochemistry, a proposed serotonergic innervation of major cerebral vessels in the rat. Previous studies had demonstrated a dense perivascular plexus of 5-hydroxytryptamine immunoreactive nerve fibres upon major cerebral vessels in this and many other species. The present work has shown, however, that 5-hydroxytryptamine immunoreactive nerve fibres are rarely observed in cerebral vessels prepared by perfusion-fixation in situ, and only form a well-developed plexus in vessels prepared, as in previous studies, by immersion-fixation. Prior treatment with a predominantly noradrenergic uptake inhibitor desmethylimipramine but not the serotonergic uptake inhibitor fluoxetine produced a major diminution in the 5-hydroxytryptamine immunoreactive plexus visualized in these immersion-fixed vessels. In addition, 5-hydroxytryptamine immunoreactive nerves were only occasionally observed in immersion-fixed vessels from animals that had been pretreated with 6-hydroxydopamine to produce adrenergic denervation. The removal, firstly, of vessel-contained blood, by left ventricular perfusion with Krebs' solution, prior to vessel dissection and immersion-fixation, resulted in an absence of 5-hydroxytryptamine immunoreactivity in perivascular nerves. Immunoreactivity could then be restored by briefly incubating vessels in Krebs' solution containing either blood or 5-hydroxytryptamine before fixation. It would appear therefore that 5-hydroxytryptamine is rarely present under normal circumstances in the perivascular nerves of major cerebral vessels, and that previous descriptions of a dense serotonergic nerve plexus represent 5-hydroxytryptamine in blood released during vessel dissection being taken up via the noradrenaline-uptake system into perivascular sympathetic nerves. The possibility is thus raised that 5-hydroxytryptamine uptake and interaction within perivascular adrenergic nerves could occur in those cerebrovascular disorders where blood is released.

Adrenergic Fibers↗
PubMed1989

Alterations in serotonin and neuropeptide Y content of cerebrovascular sympathetic nerves following experimental subarachnoid hemorrhage.

The effect of an experimental subarachnoid hemorrhage (SAH) upon neurotransmitter content in sympathetic nerves supplying the major cerebral arteries of the rat has been examined by immunohistochemical analysis and high performance liquid chromatography with electrochemical detection (HPLC-ECD). In particular, changes that occur in sympathetic nerve content of the vasoconstrictor agents serotonin (5-HT) and neuropeptide Y (NPY), which are colocalized with noradrenaline, were assessed. Subarachnoid hemorrhage was induced by a single injection of autologous arterial blood into the cerebrospinal fluid (CSF) space of the cisterna magna. The density of 5-HT-containing and NPY-containing perivascular nerve fibers per unit area of vessels was measured at defined intervals from 15 min to 5 days post-SAH. In addition, an HPLC study was performed to quantify the actual amounts of 5-HT and noradrenaline present in circle of Willis vessels at 3 h post-SAH. Comparison was made with sham-operated animals and animals that received a cisternal injection of buffered saline in place of blood. Our results reveal a major increase in cerebrovascular sympathetic nerve content of serotonin, arising by uptake, presumably from subarachnoid blood clot, within the first 3 h post-SAH. Neuropeptide Y content, however, decreased from 3 up to 48 h posthemorrhage. By 3 days post-SAH, when the majority of subarachnoid clot had resorbed, the sympathetic nerve content of both NPY and 5-HT was restored to normal. This pattern of change was not observed in either sham-operated or saline-injected controls.

Animals↗
PubMed1988

Ultrastructure of serotonin-containing nerve fibres in the middle cerebral artery of the rat and evidence for its localization within catecholamine-containing nerve fibres by immunoelectron microscopy.

This study has examined the ultrastructural characteristics of serotonin (5-HT)-like immunoreactive (5-HT-I) nerves in the perivascular plexus of a major cerebral blood vessel and their relationship with catecholaminergic (CA) nerves. This was achieved by immunohistochemistry for 5-HT used alone and in combination with simultaneous 5-hydroxydopamine (5-OHDA) false transmitter preloading to demonstrate catecholaminergic nerves examined by electron microscopy. About 15% of perivascular nerves showed some 5-HT-like immunoreactivity. These nerves were characterised by a predominance of small pleomorphic vesicles with a diameter of 40-50 nm and a few large granular vesicles about 100-150 nm diameter. 5-HT-I nerves were found at all levels of the perivascular plexus, from the outer adventitia where they were formed together with non-reactive nerves into bundles by Schwann cells and their processes, to more singly at the adventitia-media border, sometimes in close apposition to smooth muscle cells, separated by some 125 nm. Examination of animals treated by 5-OHDA preloading revealed that 5-HT-I nerves were almost invariably identified as catecholaminergic. However, CA nerves did not always show 5-HT-like immunoreactivity, some 25% only being doubly labelled in this study. Treatment of animals with the catecholaminergic nerve uptake blocker desmethylimipramine resulted in abolition of 5-HT-like immunoreactivity. These results provide direct ultrastructural evidence for the localisation of 5-HT within the perivascular catecholaminergic nerves of a major cerebral vessel and suggest that the contained 5-HT is mainly derived by uptake rather than synthesis within them.

Animals↗
PubMed1978

The reciprocal synapse in the external plexiform layer of the mammalian olfactory bulb.

It has recently been claimed by Ramon-Moliner29, that reciprocal synapses between mitral (and tufted) cell dendrites and granule cell gemmules, which for more than 10 years have been thought to represent a major feature of the structural and functional organization of the olfactory bulb28, are non-existent or, at best, extremely rare. The challenge is based on the contention that there is little, if any, morphological evidence to substantiate the existence of the gemmulofugal component of the reciprocal synapse. We have re-examined by electron microscopy the external plexiform layer (EPL) of the olfactory bulb of adult rabbits and rats. The study was carried out in conventionally prepared material, using individual and serial sections, goniometry, and quantitative analysis of montages, and also in material stained by the E-PTA and BIUL methods. According to currently accepted morphological criteria, gemmulofugal synapses can be identified consistently and with confidence at all levels in the EPL: they are particularly clearly and unambiguously resolved in E-PTA and BIUL preparations. At least the majority of gemmulofugal and mitrofugal synapses are closely associated in reciprocal pairs, as many previous authors have reported. Furthermore, there are approximately as many gemmulofugal as mitrofugal synapses in the EPL, which supports the long-standing proposal that the overall synaptic relationship between granule cells and mitral cells is a reciprocal one. We conclude that the challenge of Ramon-Moliner to the reality and significance of the reciprocal synapse is not well-founded.

Animals↗