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J Jakubowski

Publications and source records attributed to J Jakubowski.

At least 37 records · Page 2Linked to original sources
PubMed1993

Middle cerebral artery occlusion without craniectomy in rats. Which method works best?

BACKGROUND AND PURPOSE: Our purpose was to assess the effectiveness of middle cerebral artery occlusion in producing acute focal ischemia in the rat by the use of Koizumi's and Longa's methods, in which occlusion is achieved by passing a nylon thread into the internal carotid artery. METHODS: Cerebral blood flow was measured by using the hydrogen clearance method, and the brains were examined histologically to assess ischemic damage. RESULTS: By Koizumi's method profound reduction in cerebral blood flow was achieved in 28 of 30 rats (93%). The mean cerebral blood flow in the middle cerebral artery territory was 10.7 (95% confidence interval, 9.9-11.5) ml/100 g per minute. By Longa's method reduction in cerebral blood flow was achieved in only 29 of 52 rats (56%), and in these animals mean cerebral blood flow was 33 (95% confidence interval, 28.3-33.7) ml/100 g per minute (p < 0.001 compared with Koizumi's method). Cerebral blood flow was reduced to < 16 ml/100 g per minute in only seven animals (24%). CONCLUSIONS: By Koizumi's method the depth of ischemia is more profound, occlusion is achieved in a much higher proportion of cases, and the incidence of perforation of the intracranial internal carotid is much less frequent than by Longa's method.

Acute Disease↗
PubMed1992

[Computerized tomography in aneurysms of the posterior cranial fossa].

The authors discuss the clinical usefulness of CT scan in patients with ruptured posterior fossa aneurysms. Among 164 patients after SAH, in 17 the bleeding was caused by aneurysms located in posterior fossa. The exact diagnosis of the bleeding during 5 days after SAH was possible in 94% of the patients, that is similar as in supratentorial aneurysms. The characteristic symptoms of SAH in these aneurysms was the symmetric presence of blood in basal cisterns, intraventricular haemorrhage and, in consequence,--hydrocephalus. Aneurysms of bifurcation of BA were characterized by presence of blood in interpeduncular cistern; this phenomenon was not observed in PICA aneurysms. The aneurysms of BA were more often seen in direct CT-Scan.

Basilar Artery↗
PubMed1990

Vasopressin, insulin and peroxide(s) of vanadate (pervanadate) influence Na+ transport mediated by (Na+, K+)ATPase or Na+/H+ exchanger of rat liver plasma membrane vesicles.

Uptake of 22Na+ by liver plasma membrane vesicles, reflecting Na+ transport by (Na+, K+)ATPase or Na+/H+ exchange was studied. Membrane vesicles were isolated from rat liver homogenates or from freshly prepared rat hepatocytes incubated in the presence of [Arg8]vasopressin or pervanadate and insulin. The ATP dependence of (Na+, K+)ATPase-mediated transport was determined from initial velocities of vanadate-sensitive uptake of 22Na+, the Na(+)-dependence of Na+/H+ exchange from initial velocities of amiloride-sensitive uptake. By studying vanadate-sensitive Na+ transport, high-affinity binding sites for ATP with an apparent Km(ATP) of 15 +/- 1 microM were observed at low concentrations of Na+ (1 mM) and K+ (1mM). At 90 mM Na+ and 60 mM K+ the apparent Km(ATP) was 103 +/- 25 microM. Vesiculation of membranes and loading of the vesicles prepared from liver homogenates in the presence of vasopressin increased the maximal velocities of vanadate-sensitive transport by 3.8-fold and 1.9-fold in the presence of low and high concentrations of Na+ and K+, respectively. The apparent Km(ATP) was shifted to 62 +/- 7 microM and 76 +/- 10 microM by vasopressin at low and high ion concentrations, respectively, indicating that the hormone reduced the influence of Na+ and K+ on ATP binding. In vesicles isolated from hepatocytes preincubated with 10 nM vasopression the hormone effect was conserved. Initial velocities of Na+ uptake (at high ion concentrations and 1 mM ATP) were increased 1.6-1.7-fold above control, after incubation of the cells with vasopressin or by affinity labelling of the cells with a photoreactive analogue of the hormone. The velocity of amiloride-sensitive Na+ transport was enhanced by incubating hepatocytes in the presence of 10 nM insulin (1.6-fold) or 0.3 mM pervanadate generated by mixing vanadate plus H2O2 (13-fold). The apparent Km(Na+) of Na+/H+ exchange was increased by pervanadate from 5.9 mM to 17.2 mM. Vesiculation and incubation of isolated membranes in the presence of pervanadate had no effect on the velocity of amiloride-sensitive Na+ transport. The results show that hormone receptor-mediated effects on (Na+, K+)ATPase and Na+/H+ exchange are conserved during the isolation of liver plasma membrane vesicles. Stable modifications of the transport systems or their membrane environment rather than ionic or metabolic responses requiring cell integrity appear to be involved in this regulation.

Adenosine Triphosphate↗
PubMed1989

Microangiopathy in human diabetic neuropathy: relationship between capillary abnormalities and the severity of neuropathy.

Clinical, electrophysiological and ultrastructural morphometric observations were made in 5 diabetic non-neuropathic patients, 5 diabetic patients with mild neuropathy and 11 diabetic patients with severe neuropathy. Capillary abnormalities were assessed in simultaneous nerve, muscle and skin biopsies and compared with results from 6 age-matched, non-diabetic control subjects. Nerve capillaries demonstrated markedly greater pathology than skin and muscle capillaries. Endoneurial capillary density was significantly reduced in severely neuropathic diabetic patients (p less than 0.01) when compared with control subjects. Capillary basement membrane (p less than 0.002), endothelial cell (p less than 0.003) and total diffusion barrier (endothelial cell, pericyte, basement membrane) (p less than 0.001) thickness were significantly increased, and oxygen diffusing capacity was significantly reduced (p less than 0.001) in the nerves of patients with severe diabetic neuropathy when compared to control subjects. Endothelial cell profile number and luminal perimeter were significantly increased in asymptomatic (p less than 0.01), (p less than 0.05) and severely neuropathic (p less than 0.001), (p less than 0.05) diabetic patients respectively. However, endothelial cell outer perimeter, a measure of capillary size, showed no significant increase in diabetic patients when compared with control subjects. An association was observed between neurophysiological and neuropathological measures of neuropathic severity. There was no significant correlation between the duration of diabetes and HbA1 levels with capillary pathology or with neuropathic severity. Very few abnormalities of muscle and skin correlated with neuropathic severity. However, all measures of nerve capillary pathology correlated significantly with neurophysiological and neuropathological measures of neuropathic severity.

Adult↗
PubMed1989

Intracranial pressure changes following primate subarachnoid haemorrhage.

In 29 anaesthetized baboons avulsion of a small intracranial artery was used to produce a subarachnoid haemorrhage, in a closed-skull situation. Intracranial pressure was measured by extradural transducers, and arterial pressure was also measured continuously, with periodic measurements of cerebral blood flow. After haemorrhage there was an immediate fall in cerebral perfusion pressure in nearly all cases, reaching zero in 9 animals. In 18 there was a significant pressor response in the systemic circulation, but perfusion pressure usually remained low in spite of this response. Perfusion pressure recovered after a few minutes in most cases. In the 19 cases where intracranial pressure was measured on both sides, differences occurred in 11, with the higher pressure always on the same side as the haemorrhage. The difference was evident very soon after haemorrhage in 9 cases, and lasted over half an hour in 5 of them. The mechanism of arrest of bleeding was, in most of this series, not that of a zero perfusion pressure. Explanations for this and for the occurrence of differential pressures are discussed.

Animals↗
PubMed1989

Changes of blood flow in the adenohypophysis of normal and estrogen pretreated Fisher rats by tamoxifen.

Blood flow was measured in the adenohypophysis and in the cerebral cortex of female F344 rats over a period of 90 min using the hydrogen clearance method. Tamoxifen, 1 mg/kg, administered iv reduced the blood flow in the adenohypophysis by 35%, whereas cerebral blood flow and arterial pressure remained unchanged. Seven days sc treatment with tamoxifen (1 mg/kg daily) had no demonstrable effect on blood flow. Anterior pituitary hyperplasia was induced in 15 rats with diethylstilbestrol containing implants. These rats responded to 7 days of sc tamoxifen treatment by 30% increase in adenohypophyseal blood flow. These results suggest that tamoxifen has a different effect on adenohypophysial circulation of the rat depending on whether it is administered in a low- or high-estrogen state.

Animals↗
PubMed1989

Giant epidermoid cysts of the skull.

The authors describe two cases of giant intradiploic epidermoid cysts of the cranial vault and a case of a large epidermoid arising from the frontal sinus and extending intracranially. The aetiology of epithelial cysts is reviewed. The characteristic radiological and CT scan appearances of diploic epidermoid cysts are described, their clinical presentation and surgical management briefly discussed.

Adult↗
PubMed1989

Clinical evaluation of magnetic stimulation in cervical spondylosis.

Conduction in central motor pathways and motor roots was assessed, using the new technique of magnetic stimulation, in 39 patients with cervical spondylosis. Recordings were taken from abductor digiti minimi in all patients and from biceps brachii and abductor hallucis in some. Findings were abnormal ipsilaterally in 27 out of 63 muscles examined in patients with myelopathy, and in 2 out of 38 muscles in patients with radiculopathy. No abnormality was found in 11 muscles examined in patients with negative radiology. There was some correlation between the degree of electrophysiological change and clinical disability. Abnormal conduction was found in some patients with cord compression at the C3/4 or C4/5 interspace but not in a small group with compression at the C5/6 interspace. It seems that magnetic stimulation will provide objective confirmation of upper motor neurone involvement and may provide some measure of its degree, but at present it does not appear to be superior to clinical methods in diagnosing its presence. It may also aid the selection of the correct level for surgical decompression.

Adult↗
PubMed1989

A clinical evaluation of computed tomography in patients with subarachnoid haemorrhage and multiple intracranial aneurysms.

A clinical usefulness of computed tomography was reviewed in 38 consecutive patients with subarachnoid haemorrhage and multiple intracranial aneurysms. CT helped in identification of ruptured aneurysm in more than 70% of cases (it pinpointed source of bleeding in 55% of patients and showed region of haemorrhage in 15% of cases). Its main limitation was inability to detect blood in subarachnoid space (SAS) in patients who were diagnosed later after bleeding (23%). Intracerebral haematoma or localized blood accumulated in SAS showed unequivocally the burst aneurysm. Symmetrical and especially asymmetrical distribution of blood in SAS were also helpful, though the former was misleading in two cases. Moreover, CT detected hypodense lesion of brain in 2 cases, widening of ventricular system in 12 patients and directly visualized aneurysm in 3 cases.

Adult↗
PubMed1988

Primary intracerebral lymphoma: a clinicopathological analysis of 14 patients presenting over a 10-year period in Sheffield.

Intracerebral disease was diagnosed in 14 out of 450 patients who presented with non-Hodgkin's lymphoma between January 1976 and January 1987. Twelve of the 14 presented after June 1980. Age ranged from 31 to 73 years and eight patients were male. Two patients had other tumours, and three had relevant associated immunosuppressive disorders. Radiological assessment of one further patient showed a cavitating bronchial carcinoma. Five patients were untreated, and one died before radiotherapy was complete. Eight patients completed courses of whole-brain irradiation; four of these received higher doses. All entered remission. Three patients are alive, between eight months and seven years after treatment. Of the remaining five, one never recovered intellectual function and died of bronchopneumonia; three died between eight and 30 months after treatment and autopsy showed severe radionecrosis of the brain with no residual tumour. All three had received higher doses of radiation and had undergone burrhole aspiration before treatment. Autopsy was refused on one patient who also appeared to have died from radionecrosis of the brain. Immunohistological examination in eight cases confirms that cerebral non-Hodgkin's lymphoma is a B-cell tumour. As other groups have found, its incidence appears to be rising. Survival rate is poor, and at least some deaths are related to both radiation necrosis and the bulk of residual tumour after diagnostic surgery.

Adult↗
PubMed1987

Changes of blood flow in oestrogen-induced hyperplastic anterior pituitary lobe following bromocriptine administration.

Anterior pituitary hyperplasia and histologically verified adenomas were induced by diethylstilboestrol (DES) containing implants in a total of 104 female F344 rats. Thirty rats were used as controls. Blood flow in the anterior pituitary (PBF) was measured using the hydrogen clearance method. PBF was progressively reduced to 25% by DES in 13 weeks but the total adenohypophysial blood flow (flow as measured per unit weight multiplied by weight of the gland) was raised by 75%. Bromocriptine (BC, 1 mg/kg intravenously) reduced PBF by a maximum of 27% in tumour-bearing rats. When bromocriptine (1 mg/kg/day subcutaneously) was given for 7 days before the measurements the hyperplastic effect of DES on the pituitary gland and the total blood flow through the pituitary were both reduced by 23%. Reduction of blood supply may be one of the reasons that bromocriptine is clinically useful.

Adenoma↗
PubMed1986

Sural nerve oxygen tension in diabetes.

Peripheral nerve oxygen tensions were assessed in vivo by using microelectrodes to measure endoneurial oxygen tension in exposed sural nerve. In 11 diabetic patients with chronic sensorimotor neuropathy the mean endoneurial oxygen tension was 39.7 (SD 10.2) mm Hg. In all but one patient compared with none of four non-neuropathic subjects the mean nerve oxygen tensions were below dorsal foot vein values. This unphysiological state may have a role in the aetiology of diabetic neuropathy.

Adult↗
PubMed1986

Blood flow in diethylstilbestrol-induced anterior pituitary gland hyperplasia.

Anterior pituitary hyperplasia was developed in female Fisher 344 rats by subcutaneously implanted slow-release diethylstilbestrol (DES) capsules. Blood flow was measured in two separate areas of the adenohypophysis using hydrogen clearance method at 6, 9, 10, and 13 weeks after the implantation. Blood flow progressively decreased while the DES capsules were in place (normal values in ml/g/min, mean +/- SD: 0.93 +/- .12 laterally and 1.15 +/- .11 medially, decreasing to 0.25 +/- .07 and 0.24 +/- .07, respectively, by 13 weeks). Histology confirmed nodular hyperplasia, development of large vascular lakes, and hemorrhages within the adenohypophysis. Total adenohypophysial blood flow was calculated as a product of mean blood flow as measured per unit weight and the weight of the gland. This figure progressively increased from 12.7 +/- 2 to 22.2 +/- 8 microliter/min by 13 weeks. All these changes were significant at the P less than 0.001 level. These blood flow measurements suggest that the hyperplastic adenohypophysis outgrows its blood supply which is additionally compromised by "useless" pooling of blood in the vascular lakes. However, there is an overall increase in the amount of blood flowing through the hyperplastic gland which may be explained by newly formed supplying vessels.

Animals↗
PubMed1982

The pericardium as a source of prostacyclin in the dog, ox and rat.

Cyclo-oxygenase products of arachidonic acid metabolism formed by the pericardium and epicardial surface of dog heart were identified and quantitated by radioimmunoassay after separation by high-pressure liquid chromatography. Pieces of parietal pericardium, of dog, ox and rat, when incubated in vitro produced mainly 6-keto-PGF1 alpha, with lesser amounts of PGE2, PGF2 alpha and thromboxane B2. Biosynthesis of all prostanoids increased during incubation of the parietal pericardium of each species with arachidonic acid, but 6-keto-PGF1 alpha was still the major metabolite. When slices of dog heart were incubated with arachidonic acid (1 microgram/ml) the rates of 6-keto-PGF1 alpha formation by the parietal pericardium was much greater than that of the myocardium and endocardium. Epicardial slices appeared to be intermediate in 6-keto-PGF1 alpha formation. The hearts of anesthetized dogs were also irrigated in situ with Krebs' solution, and during the first 5 min of epicardial irrigation the pericardial fluid leaving the heart again contained high levels of 6-keto-PGF1 alpha, with lesser amounts of the other prostanoids. Addition of arachidonic acid (3 micrograms/ml) to the irrigating fluid caused an increase in all measured prostanoid levels, although 6-keto-PGF1 alpha remained the predominant metabolite. In contrast, intravenous infusion of isoproterenol selectively increased the release of 6-keto-PGF1 alpha from the irrigated heart. It is concluded that the pericardium and epicardium continuously release prostacyclin into the pericardial fluid, and that the increased release of this substance observed when cardiac workload increases derives mainly from these membranous sources. This raises the interesting possibility that pericardial prostacyclin might influence coronary vascular tone and chemoreflexes which arise from the epicardium during myocardial ischemia.

6-Ketoprostaglandin F1 alpha↗