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Biomedical subjects

J F Schmidt

Publications and source records attributed to J F Schmidt.

At least 19 recordsLinked to original sources
PubMed2001

Long-term outcome after neurosurgically treated spinal epidural abscess following epidural analgesia.

BACKGROUND: A recent investigation demonstrated a high incidence of epidural abscess secondary to epidural catheterization and a 50% frequency of neurologic deficits. We studied short- and long-term neurologic outcome in patients operated for spinal epidural abscess after epidural analgesia. METHODS: Nineteen patients who had undergone neurosurgical decompression and drainage of a spinal epidural abscess during a 5-year period at three neurosurgical departments in East Denmark were identified by manual review of operating lists. RESULTS: Median epidural catheterization time was 8 days (range 3-44). Preoperatively 12 patients suffered from inferior paraparesis, one had irradiating pain from the back, and 6 patients had no neurologic deficits. Postoperatively 2 patients had recovered, but 3 other patients had deteriorated; therefore, 13 patients were discharged with paresis/plegia. Seven patients died during a median follow-up time for all patients of 41.6 months. One patient recovered completely, and one suffered from minor deficits. The remaining patients suffered from paraparesis/plegia or bladder/bowel dysfunction. CONCLUSION: Overall recovery rate for patients with paresis/plegia after epidural abscess was 20%. No patients with paresis/plegia following a thoracic abscess recovered in contrast to a 50% recovery rate for patients with lumbar epidural abscess. The majority of long-term survivors had severe neurologic deficits. Abscess formation contributed to one death.

Abscess↗
PubMed1999

No effect of insulin on glucose blood-brain barrier transport and cerebral metabolism in humans.

The effect of hyperinsulinemia on glucose blood-brain barrier (BBB) transport and cerebral metabolism (CMRglc) was studied using the intravenous double-indicator method and positron emission tomography using [18F]fluorodeoxyglucose as tracer (PET-FDG). Sixteen normal healthy control subjects (25 +/- 4 years old) were studied twice during a euglycemic and a euglycemic-hyperinsulinemic condition. Our hypothesis was that high physiologic levels of insulin did not affect the BBB transport or net metabolism of glucose. During insulin infusion, arterial plasma insulin levels increased from 48.5 to 499.4 pmol/l. The permeability-surface area products for glucose and FDG BBB transport obtained with the double-indicator method remained constant during hyperinsulinemia. Similarly using PET-FDG, no changes were observed in the unidirectional clearance of FDG from blood to brain. k2* (FDG transport from brain to blood) increased significantly by 15 and 18% (gray and white matter, respectively), and k4* (dephosphorylation of FDG) increased by 18%. The increase in k2* may be caused by insulin inducing a decrease in the available FDG brain pool. The increase in k4* may be related to an increased loss of labeled products during insulin fusion. Irrespective of these changes, CMRglc remained unchanged in all brain regions. We conclude that hyperinsulinemia within the normal physiologic range does not affect BBB glucose transport or net cerebral glucose metabolism.

Adult↗
PubMed1998

[Severe infections after epidural catheterization].

The paper reviews the literature relevant to the formation of spinal epidural abscess with or without concurrent meningeal infection following epidural catheterisation. The incidence of spinal epidural abscess lies probably in the area of 1:5000 catheterisations. Immunocompromised patients and patients with catheters in situ for more than 48 hrs. are particularly prone to develop epidural abscesses. S. aureus is isolated in 35-82% of the cases. The diagnosis based upon clinical findings, laboratory studies and MRI or CT plus myelography. The mortality is 5-10%. The treatment consists of removal of the catheter, microbiological studies, surgical decompression of the spinal cord, and prolonged antibiotic treatment. It is suggested that insertion of epidural catheters is performed under strict sterility, and that disposable syringes and unbroken vials are used for each injection, which should be administered through an epidural filter. The dressing should be changed daily simultaneously with review of the patient and the insertion site.

Abscess↗
PubMed1998

Effect of aclacinomycin A on in vitro cultures of porcine lens epithelial cells.

As a potential drug for the prevention of secondary cataract formation (SCF), we investigated the effect of Aclacinomycin A (ACM) on the growth of cultures of porcine lens epithelial cells in vitro. ACM is an anthracycline that has been used in the treatment of acute myeloid leukemia in the human for many years. It has been shown to be non-mutagenic and non-carcinogenic in in vitro and in animal models. Subconfluent cell cultures were exposed to different concentrations of ACM for 5 minutes. The drug effect was evaluated by cell counts after various lengths of culture time (between 1 and 10 weeks). No cells survived the treatment with 12 or 16 microg ml-1. Cultures treated with concentrations between 0.5 and 8 microg ml-1 showed a marked decrease in cell number when compared to controls. However, reproliferation occurred at concentration up to 8 microg ml-1 after 2-6 weeks. Intraocular application of ACM might be suitable in the prevention of SCF. However, with regard to reproliferation, long-term cultures (or long-term animal models, respectively) have to be used in further evaluating the appropriate dosage for this purpose.

Aclarubicin↗
PubMed1997

Radiation response of porcine RPE cells in vitro.

PURPOSE: To investigate the antiproliferative effect of ionizing radiation on retinal pigment epithelial (RPE) cells that are supposed to play a major role in the pathogenesis of proliferative vitreoretinopathy (PVR). METHODS: RPE cells from pig eyes were irradiated with doses ranging from 4 to 16 Gy (1 Gray = 1 Joule/kilogram). Cells were counted at 1, 2, 3, and 4 weeks (Experiment 1) or 1, 2, 4, and 6 weeks (Experiment 2) after treatment. In Experiment 3, cells were trypsinized 24 h after radiation and seeded again. Colonies were counted 10 days later, and the surviving fraction was determined. RESULTS: The numbers of cells and colonies were inversely correlated to the doses applied. In Experiment 2, cell numbers of radiated cultures remained stable during the time of follow-up, whereas, in Experiment 1, significant proliferation occurred in treated cultures as well as in controls. This may be due to the higher growing rate that was found in the cultures of Experiment 2, compared to those of Experiment 1, at the time of radiation. In Experiment 3, a D0 value of 0.72 Gy was found. CONCLUSIONS: Proliferation of RPE cells can be suppressed by irradiation in a dose-dependent manner. Therefore, radiotherapy may be useful in the treatment of PVR. Its effect probably depends on the stage or activity of PVR at the time of radiation.

Animals↗
PubMed1997

Central nervous side effects after lumbar puncture. A review of the possible pathogenesis of the syndrome of postdural puncture headache and associated symptoms.

The mechanism of central nervous side effects of lumbar puncture is reviewed on the basis of the literature. The most frequent adverse effect of lumbar puncture remains the postdural puncture headache; dysfunction of certain cranial nerves occurs less frequently. Laboratory studies have shown that the production rate of CSF. Several reports suggest that lumbar CSF leakage may affect the intracranial CSF volume. There are no reports of measurement of the intracranial pressure in patients with postdural puncture headache, but there are several indications of a reduced CSF pressure that may explain postdural puncture headache and vestibulocochlear dysfunction following lumbar puncture. Recent audiometric studies suggest that hearing loss may be a sensitive indicator of CSF leakage, and larger series indicate that the needle size and the shape of the needle tip are important determinants of the incidence of central nervous side effects. Epidural blood patch may give immediate relief of postdural puncture headache and cranial nerve dysfunction after lumbar puncture, but the reason for the rapid and impressive effect of epidural blood patch has not been fully elucidated.

Blood Patch, Epidural↗
PubMed1996

Pharmacological manipulation of cardiovascular responses to lower body negative pressure.

To evaluate influences on blood volume distribution, atrial natriuretic peptide concentrations (ANP) and thoracic and leg electrical impedance at 2.5 (TI2.5 and LI2.5, respectively) and 100 kHz (TI100 and LI100, respectively) were monitored during administration of ketanserin, noradrenaline and trimetaphan combined with lower body negative pressure (LBNP) in 12 subjects. Administration of clinically relevant doses of ketanserin alone did not induce changes in mean arterial pressure (MAP) or in the central blood volume, as electrical impedance and ANP concentrations did not change. During continued infusion of ketanserin an increase in MAP from a mean of 90 (range 83-108) to 113 (range 98-138) mmHg was induced by noradrenaline, but TI2.5 [mean 45.6 (range 39.3-54.2)] and TI100 [mean 33.8 (range 27.5-38.5) omega] remainded stable until ganglionic blockade and LBNP were applied, when they increased by a mean of 3.1 (range 2.0-6.1) and 2.7 (range 1.1-4.2) omega, respectively (P < 0.05). Conversely, LI2.5 [mean 79.6 (range 74.1-89.4)] and LI100 [mean 56.7 (range 52.4-63.3) omega] decreased by a mean of 3.2 (range 1.2-8.0) and 2.3 (range 0.9-3.9) omega, ANP from a mean of 27.7 (range 10.2-62.7) to 12.7 (range 7.1-27.5) pmol.l-1 and MAP fell to a mean of 62 (range 42-70) mmHg (P < 0.05). The heart rate was a mean of 75 (range 69-77) beats.min-1 and did not change until LBNP, when it increased to a mean of 102 (range 78-104) beats.min-1, as presyncopal symptoms appeared. The data indicated that serotonergic blockade by ketanserin and alpha-sympathetic stimulation by noradrenaline did not affect blood volume distribution in normal humans, but that ganglionic blockade combined with LBNP reduced the central blood volume as leg volume increased; during central hypovolaemia tachycardia induced by ganglionic blockade did not prevent the fall in MAP, and thereby the appearance of presyncopal symptoms.

Adrenergic alpha-Agonists↗
PubMed1996

The effect of ketanserin on ICP and CBF in patients with normal-pressure hydrocephalus.

Eight patients with normal-pressure hydrocephalus were studied. Intracranial pressure (ICP) and mean arterial blood pressure (MAP) were measured continuously before and during administration of ketanserin i.v. (10 mg bolus followed by an infusion of 3 mg over a 60-min period, 6 mg over the next 30 min, and 12 mg over the last 30 min). The mean baseline MAP and ICP were 103 and 8 mm Hg, respectively. Five minutes after the bolus dose, the maximum decrease in MAP occurred (mean, 17 mm Hg; p < 0.05). The maximum ICP (10 mm Hg) occurred at 5 min and at 100 min after the bolus dose but was not significantly different from the baseline value. There was no change in relative global cerebral blood flow (CBF) expressed as 1/(arteriovenous oxygen difference). It is concluded that ketanserin in a clinically recommended dose decreases blood pressure without significantly influencing the ICP or CBF.

Adult↗
PubMed1996

Toxicity and antiproliferative effect of aclacinomycin A on RPE cells in vitro.

PURPOSE: Aclacinomycin A or aclarubicin is an anthracycline that, by contrast with daunomycin, lacks carcinogenicity and is less toxic to the retina. We investigated the toxicity and antiproliferative effect of aclacinomycin A on retinal pigment epithelial cells that are known to play a mayor role in the pathogenesis of proliferative vitreoretinopathy. METHODS: In 3 experimental set-ups, RPE cells from pig eyes were incubated with aclacinomycin A at different concentrations (0.5-15 micrograms/ml) and for various lengths of time (1-10 min). Cells were counted on day 3 after exposure to evaluate toxicity, subcultured, and counted once more on day 15 to test for the antiproliferative effect. Data were analyzed using the Tukey's Studentized Range (HSD) Test. Furthermore, RPE cells were examined by light microscopy. RESULTS: Cell numbers on day 3 after treatment were reduced significantly (p < or = 0.05) already at the lowest dosage tested (1 microgram/ml for 1 min). Higher doses, up to 15 micrograms/ml for 5 min, did not lower cell numbers below 20% of those of control cultures. Logarithms of cell numbers on day 15 were inversely correlated to drug concentration as well as to incubation time. Cells that had been treated with 5 micrograms/ml aclacinomycin A for 5 min were not able to start a new culture when subcultured 3 days after drug exposure. CONCLUSIONS: Aclacinomycin A applied intraocularly during vitreoretinal surgery may be an alternative to daunomycin in the treatment of proliferative vitreoretinopathy.

Aclarubicin↗
PubMed1995

Alterations in perivascular dilatory neuropeptides (CGRP, SP, VIP) in the external jugular vein and in the cerebrospinal fluid following subarachnoid haemorrhage in man.

A possible involvement of perivascular vasodilatory neuropeptides in subarachnoid haemorrhage (SAH) has been evaluated in man by measuring the levels of calcitonin gene related peptide (CGRP)-, substance P (SP)- and vasoactive intestinal peptide (VIP)-like immunoreactivity (LI) in the cranial venous outflow and in CSF in 34 patients admitted to the hospital after an acute SAH. After operation with aneurysm clipping and nimodipine treatment, blood samples were taken from the external jugular vein (EJV) or cerebrospinal fluid (CSF) and analysed for neuropeptide levels with specific radioimmuno assays (RIA) during the postoperative course. The degree of vasoconstriction in the patients was monitored with Doppler ultrasound recordings bilaterally from the middle cerebral (MCA) and internal carotid arteries (ICA) following the EJV blood sampling every second day. The mean value of all CGRP-LI measurements in EJV during the entire course of SAH (n = 20) revealed a significantly higher level as compared to controls. The highest CGRP-LI levels were found in patients with the highest velocity index values (vasospasm). The relationship Vmean MCA/Vmean ICA was used as an index of vasoconstriction. In patients with MCA aneurysms (n = 10), a significant correlation (r = 0.65, p < 0.05) was found between the vasospasm index and CGRP-LI levels. There were no changes observed in the SP- and VIP-LI levels. Alterations in cerebrovascular tone induced by changing arterial CO2 tension or lowering of blood pressure (ketanserin infusion test) did not alter the levels of the perivascular peptides in the EJV. In addition, CGRP-, SP-, VIP- and neuropeptide Y (NPY)-LI were analysed in CSF in the post-operative course after subarachnoid haemorrhage (SAH) in 14 patients. The CSF VIP-LI was lower in SAH than in control (p < 0.05). The CGRP-LI level was measurable in SAH CSF but not in CSF of controls. In individual patients with marked vasoconstriction increased levels of CGRP-LI (up to 14 pmol/L) and NPY-LI (up to 232 pmol/L) were observed. The results of this study are in support of our hypothesis that there is an involvement of the sensory peptide CGRP in a dynamic reflex aimed at counterbalancing vasoconstriction in SAH.

Adult↗
PubMed1995

Postdural puncture headache (PDPH): onset, duration, severity, and associated symptoms. An analysis of 75 consecutive patients with PDPH.

Among 873 consecutive patients who had undergone a total of 1021 spinal anaesthesias involving puncture of the lumbar dura, 75 (7.35%) complained of Postdural Puncture Headache (PDPH). The severity of each patient's PDPH was categorized, on a scale from mild to severe, on the basis of the onset, duration, severity of the headaches, and the degree to which they were accompanied by auditory and vestibular symptoms. In the patients who developed PDPH, 65% developed symptoms within 24 hours of the lumbar punctures and 92% developed symptoms within 48 hours. For the patients who recovered spontaneously the mean duration of the PDPHs was 5 days, with a range of 1-12 dyas. PDPH was characterized by headaches that were influenced by the patient's posture and the severity of PDPH was categorized as follows: Mild PDPH resulted in a slight restriction of their physical activity. These patients were not confined to bed and had no associated symptoms. Moderate PDPH forced the patient to stay in bed for part of the day, and resulted in restricted physical activity. Associated symptoms were not necessarily present. Severe PDPH. Patients were bedridden for the entire day and made no attempt to raise their head or to stand. Associated symptoms were always present. Forty-five of the PDPH patients (60%) recovered spontaneously. Of these, 8 patients (11%) were categorized as mild cases of PDPH, 14 (19%) as moderate, and 23 (30%) patients as severe cases of PDPH. Thirty of the PDPH patients (40%) were treated with an autologous epidural blood patch (AEBP). Of these, 27 patients (36%) were classified as severe and 3 patients (4%) as moderate PDPH.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

[Time consumption at an orthopedic operating theatre. Physicians' ability to predict their own time consumption].

The aim of the study was to investigate the time spent on different procedures in an orthopaedic operating theatre, and to evaluate the ability of doctors to predict their own time consumption. Time schedules were registered for 146 operations, of these 104 were either knee or hip replacements. Sixty percent of the total time was spent on surgery. The median misjudgment was 15 minutes for surgeons and five minutes for anaesthetists. An improvement in the doctors' ability to predict their own time consumption in the course of the study period could not be demonstrated. Comparing the study period with the similar period the year before it was not possible to demonstrate a change in the number of cancelled operations or the number of days with overtime. Epidural anaesthesia with bupivacaine was the most time consuming anaesthesia, the differences between the other forms of anaesthesia used were insignificant.

Denmark↗
PubMed1994

Evaluation of a 7.5 French pulmonary catheter for continuous monitoring of cerebral venous oxygen saturation.

We studied a 7.5 French Opticat fiberoptic catheter/Oximetrix computer system as a tool for continuous monitoring of oxygen saturation of jugular venous blood. Eight healthy volunteers had a catheter placed with the tip in the bulb of the right internal jugular vein. During baseline condition, hyperventilation, and rebreathing, jugular venous oxygen saturations ranging from 35 to 85% were obtained. Simultaneous with drawing a blood sample, the value obtained with the fiberoptic catheter was recorded. The oxygen saturation of the blood sample was analyzed in vitro using a bench oximeter. A total of 150 paired values was obtained. In 15 of these cases, the computer indicated that the intensity of the reflected light was insufficient. A difference of > 12% oxygen saturation between the paired values was obtained for all of these pairs. The regression coefficient for the remaining 135 data pairs was 0.95, the mean difference was -0.54%, and the limits of agreement were -9.5 to 8.4%. We conclude that the 7.5 French Opticat catheter is useful if values obtained during improper light intensity are excluded.

Adult↗
PubMed1993

The effect of ketanserin on cerebral blood flow and oxygen metabolism in healthy volunteers.

The effect of the anti-hypertensive agent ketanserin on average global cerebral blood flow (CBF) and average global cerebral oxygen metabolism (CMRO2) was examined in 8 healthy volunteers. CBF and CMRO2 were measured with the Kety-Schmidt technique before ketanserin administration (baseline) and after administration of 2 different doses of ketanserin intravenously (dose I: 10 mg bolus and an infusion of 6 mg/h; dose II: 20 mg bolus and an infusion of 20 mg/h). Baseline CBF and CMRO2 were 60 and 3.6 ml/100 g/min, respectively, and were not changed by administration of ketanserin dose I. During administration of dose II, however, CBF fell to 52 ml/100 g/min (p = 0.05) and CMRO2 was reduced to 3.2 ml/100 g/min (p < 0.05). We conclude that when administered in a high dose, ketanserin has the ability to depress cerebral oxygen metabolism, but when administered in a clinically relevant dose ketanserin does not influence average global CBF or average global CMRO2. Ketanserin could be a safe antihypertensive drug in neuroanaesthesia or in the neuro-intensive care unit.

Adult↗
PubMed1993

High resolution SPECT with [99mTc]-d,l-HMPAO in normal pressure hydrocephalus before and after shunt operation.

Cranial CT and high resolution measurements of regional cerebral blood flow (rCBF) with brain dedicated single photon emission computer tomography (SPECT) and [99mTc]-d,l-hexamethylpropyleneamine oxime ([99mTc]-d,l-HMPAO) were performed before and after shunt operation in 14 consecutive patients with dementia and normal pressure hydrocephalus (NPH). When compared with a control group of 14 age matched healthy volunteers, the group of NPH patients was characterised by an enlarged subcortical low-flow region, significantly reduced rCBF and enhanced side-to-side asymmetry of rCBF in the central white matter, and enhanced side-to-side asymmetry in the inferior and mid-temporal cortex. Global CBF was normal. Shunt operation reduced the mean area of the ventricles on CT and of the subcortical low-flow region on SPECT. Global CBF was unchanged. All 14 patients had an abnormal pre-shunt rCBF pattern with enlargement of the subcortical low flow region, focal cortical blood flow deficits, or both. Shunt operation improved the clinical status in 11 patients, and the area of the subcortical low flow region correctly classified 3/3 unimproved and 10/11 improved patients. Shunt operation normalised or reduced the area of the subcortical low flow region in nine of 10 patients. It is concluded that SPECT with [99mTc]-d,l-HMPAO is a useful supplement in the diagnosis of NPH versus normal ageing, and that SPECT may help to identify patients not likely to benefit clinically from surgery.

Adult↗
PubMed1993

Middle cerebral artery blood velocity and cerebral blood flow and O2 uptake during dynamic exercise.

Results obtained by the 133Xe clearance method with external detectors and by transcranial Doppler sonography (TCD) suggest that dynamic exercise causes an increase of global average cerebral blood flow (CBF). These data are contradicted by earlier data obtained during less-well-defined conditions. To investigate this controversy, we applied the Kety-Schmidt technique to measure the global average levels of CBF and cerebral metabolic rate of oxygen (CMRO2) during rest and dynamic exercise. Simultaneously with the determination of CBF and CMRO2, we used TCD to determine mean maximal flow velocity in the middle cerebral artery (MCA Vmean). For values of CBF and MCA Vmean a correction for an observed small drop in arterial PCO2 was carried out. Baseline values for global CBF and CMRO2 were 50.7 and 3.63 ml.100 g-1.min-1, respectively. The same values were found during dynamic exercise, whereas a 22% (P < 0.0001) increase in MCA Vmean was observed. Hence, the exercise-induced increase in MCA Vmean is not a reflection of a proportional increase in CBF.

Adult↗