Plastic foil technique attenuates inflammation in mesenteric intravital microscopy

BACKGROUND

Interpretation of intravital microscopic observations is complicated by the "inflammatory"-type response to the trauma inflicted on the tissue by the surgical preparation. The present study evaluates different experimental conditions for prolonged observations of the mesenteric microcirculation in the rat.

METHODS

The mesentery was exteriorized through a median laparotomy and subjected to an organ bath or a modified plastic foil technique. Hemodynamic, metabolic, respiratory, and microcirculatory data were analyzed.

RESULTS

In contrast to the plastic foil technique, which yielded stable baseline values over a 5-h observation period, venular velocity and wall shear rates decreased significantly in the organ bath technique, and leukocyte adhesion to the endothelium was significantly increased. Likewise, abdominal blood flow decreased significantly by 35% and base excess declined (-10.0+/-0.4 mmol/L) in the organ bath, with reduced pco(2) (26.4+/-2.5 mm Hg vs. 33.7+/-1.1 mm Hg in plastic foil technique) due to respiratory pH compensation.

CONCLUSIONS

The plastic foil technique was found clearly superior to the organ bath technique for maintenance of stable baseline metabolic, hemodynamic, and microcirculatory conditions in mesenteric intravital microscopy.

Investigation of iodine-123-labelled amino acid derivatives for imaging cerebral gliomas: uptake in human glioma cells and evaluation in stereotactically implanted C6 glioma rats

In developing iodine-123-labelled amino acid derivatives for imaging cerebral gliomas by single-photon emission tomography (SPET), we compared p-[123I]iodo-L-phenylalanine (IPA), L-[123I]iodo-1,2,3,4-tetrahydro-7-hydroxyisoquinoline-3-carboxylic acid (ITIC) and L-3-[123I]iodo-alpha-methyltyrosine (IMT) with regard to their uptake in human glioblastoma T99 and T3868 cells, and thereafter studied the mechanisms promoting the cellular uptake. The potential of the 123I-iodinated agents for use as SPET radiopharmaceuticals was evaluated in healthy experimental rats as well as in rats with stereotactically implanted C6 gliomas. The radiopharmaceutical uptake into glioblastoma cells was rapid, temperature and pH dependent, and linear during the first 5 min. Equilibrium was reached after 15-20 min, except in the case of ITIC, the initial uptake of which gradually decreased from 15 min onwards. The radioactivity concentration in glioma cells following 30-min incubation at 37 degrees C (pH 7.4) varied from 11% to 35% of the total activity per million cells (ITIC < IMT < or = IPA). Competitive inhibition experiments using alpha-(methylamino)-isobutyric acid and 2-amino-2-norbornane-carboxylic acid, known as specific substrates for systems A and L, respectively, as well as representative amino acids preferentially transported by system ASC, indicated that IPA, like IMT, is predominantly mediated by the L and ASC transport systems, while no significant involvement of the A transport system could be demonstrated. By contrast, none of the three principal neutral amino acid transport systems (A, L and ASC) appear to be substantially involved in the uptake of ITIC into glioblastoma cells. Analysis of uptake under conditions that change the cell membrane potential, i.e. in high K+ medium, showed that the membrane potential plays an important role in ITIC uptake. Alteration of the mitochondrial activity by means of valinomycin or nigericin induces a slight increase or decrease in the radiopharmaceutical uptake, suggesting a minor contribution of the mitochondria in the uptake. IPA, IMT and ITIC passed the blood-brain barrier, and thereafter showed efflux from the brain. The radioactivity concentration in healthy rat brain 15 min following intravenous injection varied from 0.07% (ITIC) to 0.27% ID/g (IPA). In comparison, the brain uptake in the stereotactically implanted C6 glioma rats was substantially higher (up to 1.10% ID/g 15 min p.i.), with tumour-to-background ratios greater than 4. These data indicate that IPA and ITIC, like IMT, exhibit interesting biological characteristics which hold promise for in vivo brain tumour investigations by SPET.

Tolerance-Inducing dose of 3-nitropropionic acid modulates bcl-2 and bax balance in the rat brain: a potential mechanism of chemical preconditioning

Many studies have reported ischemia protection using various preconditioning techniques, including single dose 3-nitropropionic acid (3-NPA), a mitochondrial toxin. However, the cellular signal transduction cascades resulting in ischemic tolerance and the mechanisms involved in neuronal survival in the tolerant state still remain unclear. The current study investigated the mRNA and protein expression of the antiapoptotic bcl-2 and the proapoptotic bax. two antagonistic members of the bcl-2 gene family, in response to a single dose of 3-NPA, to global cerebral ischemia-reperfusion. and to the combination of both 3-NPA-pretreatment and subsequent global cerebral ischemia-reperfusion. Brain homogenates of adult Wistar rats (n = 25) were analyzed for bcl-2 and bax mRNA expression using a new highly sensitive and quantitative polymerase chain reaction (PCR) technique that allows real-time fluorescence measurements of the PCR product (LightCycler; Roche Diagnostics, Mannheim, Germany). Animals for mRNA analysis received 3-NPA (20 mg/kg, intraperitoneal; "chemical preconditioning") or vehicle (normal saline), and were either observed for 24 plus 3 hours or were subjected to 15 minutes of global cerebral ischemia 24 hours after the pretreatment and observed for 3 hours of reperfusion. Immunohistochemistry was applied to serial brain sections of additional rats (n = 68) to determine amount and localization of the respective Bcl-2 and Bax protein expression in various brain areas. One set of animals was injected with 3-NPA and observed for 3, 12, 24, and 96 hours; a second set was exposed to 15 minutes global cerebral ischemia, 3, 12, and 24 hours reperfusion; and a third set was pretreated with 3-NPA or saline 24 hours before the ischemic brain insult and observed for 96 hours of reperfusion. The authors found single dose 3-NPA treatment to be associated with an elevated bcl-2:bax ratio (increased bcl-2 expression, decreased bax expression), both on the transcriptional (mRNA) and the translational (protein) level. The differential influence of 3-NPA was maintained during early recovery from global cerebral ischemia (3 hours), when 3-NPA pretreated animals showed higher bcl-2 and lower bax mRNA levels compared with rats with saline treatment. Respective changes in protein expression were localized predominately in neurons vulnerable to ischemic damage. Compared with baseline, Bcl-2 protein was significantly higher in surviving neurons at 96 hours after the insult, whereas Bax protein remained unchanged. However, at this late time of postischemic recovery (96 hours), the protein expression pattern of surviving neurons was not different between animals with and without 3-NPA pretreatment. To the authors' knowledge, the current study is the first report on the differential expression of pro- and antiapoptotic genes after a single, nonlethal dose of 3-NPA. The current results suggest alterations in the balance between pro- and antiapoptotic proteins as a potential explanation for the reported protection provided by chemical preconditioning using 3-NPA in rats.

Ex vivo study of the physical effect of coils on pressure and flow dynamics in experimental aneurysms

BACKGROUND AND PURPOSE

Recent experimental studies and a few case reports reveal that coiling may not lead to permanent occlusion of aneurysms by an organized thrombus. Therefore, biologic long-term prognosis seems to be doubtful, and the physical effect of coils may be important. The purpose of this study was to investigate the physical effect of coils on pressure and flow dynamics in aneurysms.

METHODS

Bifurcation aneurysms were created in eight rabbits, explanted after 3 weeks, and tested in a model with pulsatile perfusion with 0.9% saline and heparinized blood. Before and after densely packing with coils, systemic and intraaneurysmal pressure, aneurysmal pulsation, and impact measurements were recorded.

RESULTS

The peak and shape of the pressure waves in the aneurysm and in the delivery system were not significantly different before and after coiling. Under physiological intraaneurysmal pressure (while being perfused with saline), significant reduction (P = .022) of aneurysmal wall pulsation after coil embolization was noted. Overall, the aneurysmal impact on surrounding structures was statistically unchanged after coiling. However, in a few cases, after coil embolization, the observed increase of impact was more than doubled compared with the original values before coiling.

CONCLUSION

Coils do not physically affect intraaneurysmal pressure. After coiling, there is no significant reduction of flow rates through the aneurysm and no reduction of aneurysmal impact, but aneurysmal wall pulsation may be decreased.

Early-onset tolerance in rat global cerebral ischemia induced by a mitochondrial inhibitor

It was studied whether a subtoxic dose of the mitochondrial neurotoxin, 3-nitropropionic acid (3-NPA), can initiate early-onset tolerance induction for subsequent ischemic injury. Wistar rats were pretreated for 3 h by intraperitoneal 3-NPA (20 mg/kg body weight; n=13) or solvent (n=12). Fifteen minutes global cerebral ischemia was induced by bilateral carotid artery occlusion and hypobaric hypotension. rCBF and tissue hemoglobin oxygen saturation were measured by laser Doppler scanning and a microspectrophotometric method. Ischemic insult and brain temperature were identical in both groups. Body weight and neurological scores recovered in the pretreated group but further deteriorated in the non-treated group (P<0.05). Quantitative histology demonstrated a better neuronal density in neocortex and hippocampal CA2, CA3, and CA4 of pretreated animals (P<0.05).

Hypertonic/hyperoncotic resuscitation after intestinal superior mesenteric artery occlusion: early effects on circulation and intestinal reperfusion

The objective of the study was to determine the early effects of hypertonic/hyperoncotic starch resuscitation after 2 h occlusion of the superior mesenteric artery (SMA) in comparison to animals reperfused without treatment and isotonic resuscitation. SMA was clamped (18 pigs, 19-23 kg) for 2 h followed by a 2-h reperfusion period, which was initiated with isotonic (ISO) (35 mL/kg 0.9% NaCl and 5 mL/kg 10% hydroxyethyl starch within 30 min) or hypertonic/hyperoncotic resuscitation (HHES) (7.5% NaCl/10% hydroxyethyl starch within 5 min). Cardiac output (CO), mean arterial blood pressure (MAP), serum lactate, antimesenteric serosal Laser-Doppler values (LD), and intramural pHi (tonometry) were measured. Without resuscitation at the onset of reperfusion MAP (70 +/- 3 mmHg) decreased to 40 +/- 3 mmHg and CO to 31% of baseline values after 30 min. Serum lactate increased to 5.1 +/- 1.6 mmol/L without improvement. The decrease of CO was attenuated only during the initial 30 min of reperfusion in the ISO group, but significantly better counteracted by hypertonic/hyperoncotic resuscitation. Without treatment, LD flow of the ileum (baseline 23-27 LD units) recovered but intramural pH (pHi) remained significantly decreased (7.26 +/- 0.05). With isotonic resuscitation LD values (21.8 +/- 2.1 LD units) and intramural pHi (7.09 +/- 0.14) decreased even more (P < 0.05) whereas the HHES group showed a significant hyperemic reaction and a normalization of the intramural pHi and serum lactate within 30 min. Hypertonic/hyperoncotic resuscitation significantly improves MAP and CO during reperfusion shock and induces an immediate hyperemic reperfusion reaction of the intestinal microcirculation. Adequate isotonic fluid replacement in order to restore the postischemic plasma volume loss may cause a pronounced deterioration of intestinal perfusion.

Tightness of duraplasty in rabbits: a comparative study

OBJECTIVE

The purpose of this study was to test, in rabbits, the tightness of seven dural substitution materials commonly used in neurosurgery, i.e., Lyodura (B. Braun Melsungen AG, Melsungen, Germany), Tutoplast dura (Tutogen Medical, Inc., Parsippany, NJ), Tutoplast fascia lata (Tutogen Medical, Inc.), autologous periosteum, Neuropatch (B. Braun Melsungen AG), Dacron (E.I. du Pont de Nemours and Co., Wilmington, DE), and Ethisorb (Ethicon, Inc., Somerville, NJ).

METHODS

Duraplasties were performed with sutures alone or were additionally fixed with fibrin glue. Leakage pressures were assessed by infusion of artificial cerebrospinal fluid, containing sodium fluorescein, into the cisterna magna and detection of fluorescence using a charge-coupled display camera with background substraction, 3 days, 3 weeks, or 3 months after surgery.

RESULTS

Three days after implantation, the mean tightness values of duraplasties with Lyodura or Neuropatch were significantly higher (P = 0.007) than the values for the other substitutes. A significant improvement of tightness with increasing implantation time could be demonstrated for autologous periosteum (P = 0.0063). Improvement of tightness with the use of fibrin glue could be proven only for the heterologous grafts (P = 0.0071). The tightness values for Neuropatch fixed only with sutures were similar to those for the best heterologous substitutes implanted with additional fibrin glue. Lyodura, Tutoplast dura, and Neuropatch demonstrated favorable implantation characteristics; they were thin, flexible, and easily suturable. Neither adhesions to the brain nor space-occupying scars were noted.

CONCLUSION

These results confirm the excellent suitability of Lyodura and Neuropatch for dural substitution.

Stimulatory effect of dexamethasone on angiotensin-converting enzyme in neonatal rat cardiac myocytes

Angiotensin-converting enzyme (ACE) plays a central role in cardiac remodeling associated with pathological conditions such as myocardial infarction. The existence of different cell types in the heart expressing components of the renin-angiotensin system makes it difficult to evaluate their relative role under physiological and pathological conditions. Since myocytes are the predominant cellular constituent of the heart by mass, in the present study we studied the effects of glucocorticoids on ACE activity using well-defined cultures of neonatal rat cardiac myocytes. Under steady-state conditions, ACE activity was present at very low levels, but after dexamethasone treatment ACE activity increased significantly (100 nmol/l after 24 h) in a time-dependent fashion. These results demonstrate the influence of dexamethasone on ACE activity in rat cardiac myocytes. This is consistent with the idea that ACE activation occurs under stress conditions, such as myocardial infarction, in which glucocorticoid levels may increase approximately 50-fold.

Significance of resting and stimulated cerebral blood flow for predicting the risk of hemodynamic cerebral ischemia in a model of chronic hemodynamic insufficiency

OBJECTIVE

It has been postulated that patients with a compromised cerebrovascular reserve capacity (RC), defined as cerebral blood flow (CBF) response to acetazolamide (ACZ) (by percent), are at higher risk for ischemic stroke. The value of CBF and RC for predicting the risk of hemodynamically induced impairment of cerebral function is examined.

METHODS

Both common carotid arteries were occluded in 22 Wistar-Kyoto rats. Thirty-one days later, mean arterial blood pressure was reduced to 40 mm Hg for 30 minutes. Laser Doppler scanning of CBF at resting conditions and after intraperitoneal administration of ACZ (0.1 mg/g body weight) was performed 30 minutes and 28 days after occlusion as well as before and during hypotension. Memory and motor functions were examined before and after CBF measurements.

RESULTS

After occlusion, CBF dropped significantly and ACZ did not increase CBF. Four weeks later, resting CBF had significantly improved but remained impaired, as did RC, showing a distinct interindividual variability. Hypotension reduced CBF by 57 +/- 4% (P < 0.001) and significantly impaired memory and motor functions. CBF during hypotension correlated with resting CBF before hypotension (r = 0.495, P = 0.027) and with CBF before (r = 0.392, P = 0.048) and after (r = 0.476, P = 0.034) ACZ, as determined 4 weeks after occlusion. There was no correlation with RC (r = 0.091, P = 0.702). Neurological tests performed 1 day after hypotension correlated with CBF during hypotension (memory function, P = 0.03; motor function, P = 0.02) but not with RC.

CONCLUSION

In this model of chronic hemodynamic insufficiency, the risk of impairment to global cerebral function was predicted by resting CBF and CBF after ACZ but not by RC determined with ACZ.

Effects of cortical spreading depression on cortical blood flow, impedance, DC potential, and infarct size in a rat venous infarct model

A cortical venous infarction model has been evaluated as to the degree of regional flow reduction and by studying effects of cortical spreading depression (CSD). Two adjacent cortical veins were occluded photochemically with rose bengal and fiberoptic illumination. Seven rats served to demonstrate effects on regional cortical blood flow using laser Doppler scanning. In 36 rats local CBF, DC potential, and brain tissue impedance were measured continuously for 75 min after vein occlusion. No, 3, or 10 CSD waves were induced by potassium chloride injection during the initial 75 min. Rats were compared for spontaneous CSDs; baseline local CBF, CBF, and impedance response to CSD; and infarct volume. Seventy-five minutes after vein occlusion regional cortical flow in a 3.5x7-mm window was reduced to 34.3+/-13.2%. At 45% of the 840 measured locations in 7 rats flow was <40% baseline and at 27.3% <30%, indicating a widespread penumbra territory. During the initial 75 min 2.1+/-1.1 spontaneous CSDs were observed. There was a positive correlation between the number of spontaneous CSDs seen acutely and infarction volume after 5 days. Moreover, brain injury was significantly increased in the group with 10 KCl-induced CSDs. A reduced 1CBF response and an overshooting tissue impedance change during CSD were predictors of ischemic damage. This study demonstrates a CSD-related growth of the venous infarct. Second, the data indicate that flow after two-vein occlusion resembles that seen under penumbra conditions, allowing for studies of damage mechanisms responsible for infarct growth.

Control of brain temperature during experimental global ischemia in rats

Temperature control during experimental ischemia continues to be of major interest. However, if exposure of brain tissue is necessary during the experiment, regional heat loss may occur even when the core temperature is maintained. Furthermore, valid non-invasive brain temperature monitoring is difficult in small rodents. This paper describes a method for both monitoring and maintenance of brain temperature during small animal preparations in a stereotaxic frame. The device used includes an ear-bar thermocouple probe and a small near-infrared radiator. The new equipment permitted to maintain peri-ischemic brain temperature at a desired level while carrying out non-invasive continuous recordings of cerebral blood flow (laser Doppler-flowmetry) and of electrical brain function (EEG). In contrast, without extracranial heat application, superficial and basal brain temperatures decreased during global cerebral ischemia by 4.1 +/- 0.1 and 4.6 +/- 0.4 degrees C (mean +/- SEM), respectively, returning to baseline values at 15-30 min of reperfusion while rectal (core) temperature remained stable at baseline values. The ear-bar thermocouple probe (tympanic membrane) reliably reflected basal brain temperature, and temperature in superficial brain areas correlated well with that in the temporal muscle. Our data show that the new system allows to exclude unwanted hypothermic neuroprotection, and does not interfere with optical and electrical measurement techniques.

Modelling of the ischemic penumbra

What happens to the ischemic penumbra--defined as a territory of critically reduced blood flow in the close neighborhood of an ischemic core--determines outcome after stroke. Currently the pathophysiology of the penumbra is studied predominantly in rat models with occlusion of the middle cerebral artery. Here we propose two other rat models with distinct advantages. One produces a large territory of critical flow reduction in the cortex of one hemisphere without presence of an infarct core: this model is suited to study mediator mechanisms that may transform the penumbra into necrotic tissue. It is produced by occluding one carotid artery and in addition reducing arterial pressure to 50 mm Hg using the hypobaric hypotension technique. Cortical flow is assessed by laser Doppler scanning. The second mode involves the photochemical occlusion of two adjacent cortical veins and goes along with a rather widespread reduction of cortical flow and the development of small infarcts of 2-5 mm3 infarct volume. Like the first model it is suited to administer mediators causing the infarct to grow in size, and thereby to evaluate the pathophysiologic significance of individual mediator mechanisms. In addition the model can be used to study specific therapeutic approaches.

C1-esterase inhibitor reduces infarct volume after cortical vein occlusion

In order to clarify the role of complement as a mediator of cerebral infarct growth, we inhibited the classical complement activation pathway in a photochemical cortical vein occlusion model. Immediately after occlusion, rats were infused with either 0.9% saline (vehicle), or C1-esterase inhibitor (C1-INH) over 30 min. Regional cerebral blood flow (rCBF) decreased after occlusion, and was about 50% of baseline after 2 h. No difference was noted between experimental groups. Mean arterial blood pressure (MABP) and arterial blood gases were likewise unaffected by the treatment. However, administration of C1-INH had significantly reduced infarct volume by 72%, as evaluated after 5 days survival. Thus, the neuroprotective effect cannot be explained by an improvement of cerebral perfusion but rather by protection of the parenchyma in the penumbra.

Surgical procedure affects physiological parameters in rat myocardial ischemia: need for mechanical ventilation

Several surgical approaches are being used to induce myocardial ischemia in rats. The present study investigated two different operative procedures in spontaneously breathing and mechanically ventilated rats under sham conditions. A snare around the left coronary artery (LCA) was achieved without occlusion. Left lateral thoracotomy was performed in spontaneously breathing and mechanically ventilated rats (tidal volume 8 ml/kg) with a respiratory rate of 90 strokes/min at different levels of O2 supplementation (room air and 30, 40, and 90% O2). All animals were observed for 60 min after thoracotomy. Rats operated with exteriorization of the heart through left lateral thoracotomy while breathing spontaneously developed severe hypoxia and hypercapnia despite an intrathoracic operation time of <1 min. Arterial O2 content decreased from 18.7 +/- 0.5 to 3.3 +/- 0.9 vol%. Lactate increased from 1.2 +/- 0.1 to 5.2 +/- 0.3 mmol/l. Significant signs of ischemia were seen in the electrocardiogram up to 60 min. Mechanically ventilated animals exhibited a spectrum ranging from hypoxia (room air) to hyperoxia (90% O2). In order not to jeopardize findings in experimental myocardial ischemia-reperfusion injury models, stable physiological parameters can be achieved in mechanically ventilated rats at an O2 application of 30-40% at 90 strokes/min.

Laser-Doppler scanning of local cerebral blood flow and reserve capacity and testing of motor and memory functions in a chronic 2-vessel occlusion model in rats

BACKGROUND AND PURPOSE

An animal model of incomplete forebrain ischemia resembling human hemodynamic insufficiency was established. The model allows examination of acute and chronic changes of local cerebral blood flow (lCBF) and reserve capacity in correlation with behavioral parameters.

METHODS

Anesthetized male Wistar-Kyoto rats underwent bilateral carotid occlusion (BCO). Laser-Doppler scanning of lCBF at baseline conditions and after acetazolamide was done 30 minutes after BCO, motor and memory function tests were administered after 1 and 2 days, and both investigations were repeated after 1, 2, 4, and 6 weeks. A sham-operated and a control group without any vessel manipulation served as controls.

RESULTS

lCBF dropped within 60 minutes after surgery by 62% (P<0.001) in 10 animals surviving BCO (BCOsurvival) and by 69% in 5 rats that died within 9 days (BCOlethal). Acetazolamide increased lCBF to 142.33% in controls, to 136.66% in sham-operated rats (both significant), and to 104.80% in BCOsurvival (not significant), and it decreased flow by 23.1% in BCOlethal rats (P<0.001). Baseline lCBF normalized within 4 weeks. Total motor function scores were significantly reduced from 9 points preoperatively to 5.80+/-0.65 in BCOlethal and 6.68+/-0.54 points in BCOsurvival rats 1 day after occlusion. Memory retention function remained impaired after BCO, as did the acetazolamide response, which correlated with motor score and was inversely related to maze exploration time.

CONCLUSIONS

This model allows long-term follow-up of cerebral function, lCBF, and reserve capacity in a pathophysiological setting similar to hemodynamic insufficiency in humans.

In vitro and in vivo porphyrin accumulation by C6 glioma cells after exposure to 5-aminolevulinic acid

Several malignant tissues synthesize endogenous porphyrins after exposure to 5-aminolevulinic acid (5-ALA). The present experiments have been designed to elucidate whether the C6 glioma cell, a model cell for human malignant glioma, similarly synthesizes porphyrins when exposed to 5-ALA, and whether specific synthesis occurs when C6 cells are inoculated into rat brains to form a tumor. In this situation the blood-brain barrier may interfere with 5-ALA availability, and spreading of porphyrins with edema outside the tumor may occur. Flow cytometry is used to determine the course of cell volume and porphyrin fluorescence intensities in cultured C6 cells which are incubated in 1 mM 5-ALA. For the induction of experimental brain tumors, 10(4) untreated C6 cells are inoculated into the brains of rats. After 9 days animals receive 100 mg 5-ALA/kg body weight. Brains are removed after 3, 6, or 9 h and frozen coronal sections obtained for H/E staining or fluorescence spectography. Cultured C6 cells show a linear increase of protoporphyrin IX fluorescence after exposure to 5-ALA, which begins to plateau after 85 min. Marked fluorescence is also observed in solid and infiltrating experimental tumor. However, faint fluorescence also occurs in normal tissue, basal pia, choroid plexus, and, more obviously, in white-matter tracts bordering the tumor (maximal distance: 1.5 +/- 0.7 mm). The observations demonstrate that C6 cells synthesize protoporphyrin IX after exposure to 5-ALA in vitro and in vivo. However, when utilizing 5-ALA for fluorescence detection or photodynamic therapy of brain tumors, attention should be paid to the possibility of protoporphyrin IX occurring outside the tumor.

Postischemic application of lipid peroxidation inhibitor U-101033E reduces neuronal damage after global cerebral ischemia in rats

BACKGROUND AND PURPOSE

The lipid peroxidation inhibitor U-101033E was examined for effects on cerebral blood flow (CBF), cortical tissue hemoglobin oxygen saturation (HbSo2), and neuronal damage.

METHODS

Fifteen minutes of global cerebral ischemia was induced by two-vessel occlusion and hypobaric hypotension. Wistar rats (n = 25) were randomized to receive vehicle (n = 9) or 40 mg/kg U-101033E (n = 9) intraperitoneally during 2 hours of reperfusion. A sham group (n = 7) had neither ischemia nor therapy. Histology was evaluated 7 days after ischemia.

RESULTS

During late hyperperfusion (at 17 minutes), vehicle-treated animals had a higher (P = 0.044) cortical tissue HbSo2 (72.0 +/- 1.4%) than did U-101033E-treated animals (65.8 +/- 2.5%). Neuronal counts in the superficial cortex layer found after 7 days correlated negatively with rCBF (r = -0.76; P < 0.001) or cortical tissue HbSo2 (r = -0.56; P = 0.028) assessed during the late hyperperfusion phase. U-101033E reduced neuronal damage in hippocampal CA1 from 64.3 +/- 9.2% to 31.2 +/- 8.4% (P = 0.020), as well as in the superficial cortical layer from 53.5 +/- 14.6% to 12.8 +/- 11.7% (P = 0.046). While animals in the vehicle group had reduced counts in all four examined cortex layers (P < 0.05 versus sham group), there was significant cortical neuron loss in the U-101033E group in only one of four areas. U-101033E had no effect on resting CBF or CO2 reactivity.

CONCLUSIONS

Postischemic application of U-101033E protects hippocampal CA1 and cortical neurons after 15 minutes of global cerebral ischemia. The results indicate that free radical-induced lipid peroxidation contributes to reperfusion injury, a process that can be inhibited by antioxidants such as U-101033E.

Microcirculation after cerebral venous occlusions as assessed by laser Doppler scanning

Research on cerebral venous circulation disturbances (CVCDs) has been limited partly by the paucity of animal models that produce consistent venous infarction. Occlusion of two adjacent cortical veins in rats by means of a photochemical thrombotic technique provides a minimally invasive, clinically relevant, and reproducible model suited to study the pathophysiology of CVCDs. In this study, the effects of venous occlusion on regional cortical blood flow and the brain damage that ensues were evaluated. Cortical vein occlusion was induced by photoactivation of rose bengal via 100-microm fiberoptic illumination. The cerebral venous flow pattern was examined using fluorescence angiography until 90 minutes after venous occlusion, and regional cerebral blood flow (rCBF) was determined at 48 locations by using laser Doppler scanning. Histological damage was assessed 48 hours after vein occlusion. Occlusion of two cortical veins (Group T; seven animals) was compared with single-vein occlusion and its ensuing brain damage (Group S; five animals) and with sham-operated control (five animals). An rCBF reduction occurred 30 minutes after occlusion in Group T and was more extensive than the decrease in Group S after 60 minutes. Observation frequency histograms based on local CBF data obtained in Group T demonstrated that local CBF at some sites decreased to a level below the ischemic threshold within 90 minutes. Six of the seven rats in Group T had a growing venous thrombus with extravasation of fluorescein. The resulting infarction was significantly larger in Group T (9.8 +/- 4.5% of the hemispheric area) than in Group S (only 3 +/- 1.5% of the hemispheric area). In conclusion, microcirculation perturbations occur early after venous occlusion and result in the formation of a venous thrombus accompanied by local ischemia and severe venous infarction. The extent of vein occlusion determines the resulting brain damage. Based on the results of this study, the authors conclude that CVCDs may be attenuated by prevention of venous thrombus progression together with the use of protective measures against the consequences of ischemia.

Intracoronary application of C1 esterase inhibitor improves cardiac function and reduces myocardial necrosis in an experimental model of ischemia and reperfusion

BACKGROUND

Myocardial injury from ischemia can be aggravated by reperfusion of the jeopardized area. The precise underlying mechanisms have not been clearly defined, but proinflammatory events, including complement activation, leukocyte adhesion, and infiltration and release of diverse mediators, probably play important roles. The present study addresses the possibility of reducing reperfusion damage by the application of C1 esterase inhibitor (C1-INH).

METHODS AND RESULTS

Cardioprotection by C1-INH 20 IU/kg IC was examined in a pig model with 60 minutes of coronary occlusion, followed by 120 minutes of reperfusion. C1-INH was administered during the first 5 minutes of coronary reperfusion Compared with the NaCl controls, C1-INH reduced myocardial injury (48.8 +/- 7.8% versus 73.4 +/- 4.0% necrosis of area at risk, P < or = .018). C1-INH treatment significantly reduced circulating C3a and slightly attenuated C5a plasma concentrations. Myocardial protection was accompanied by reduced plasma concentration of creatine kinase and troponin-T. C1-INH had no effect on global hemodynamic parameters, but local myocardial contractility was markedly improved in the ischemic zone. In the short-axis view, 137 degrees of the anteroseptal region showed significantly improved wall motion at early and 29 degrees at late reperfusion with C1-INH treatment.

CONCLUSIONS

C1-INH significantly protects ischemic tissue from reperfusion damage, reduces myocardial necrosis, and improves local cardiac function.

Local cerebral blood flow in a rat cortical vein occlusion model

The symptoms following sinus and vein occlusion observed in patients and experimental animals display a considerable variability that so far remains largely unexplained. In a rat cortical vein occlusion model using a photochemical thrombotic technique, we examined changes in the cerebral venous flow pattern by fluorescence angiography and regional cerebral blood flow (rCBF) and cerebral blood volume fraction (CBVF) by a modern laser Doppler "scanning" technique. Brain damage was assessed histologically. Fluorescence angiographic findings fell into two groups: group A, rats with an altered venous flow pattern after occlusion (n = 12), and group B, rats with interruption of blood flow and/or a growing venous thrombus (n = 5). In addition, sham-operated animals made up group C (n = 5). Extravasation of fluorescein, a massive decrease in rCBF, a short-lasting increase in CBVF, and regional brain damage were typical for group B. In addition, cortical CBF mapping revealed a transient hyperperfusion zone with hyperemia surrounding a hypoperfused ischemic core in group B. A circulation perturbation following venous occlusion appeared near those occluded cerebral veins without sufficient collateral flow. Furthermore, the venous thrombus continued to grow, accompanied by local critical ischemia and severe brain damage. Conversely, 71% of the animals (12 of 17) tolerated occlusion of a solitary vein without major flow disturbances or histological evidence of damage to the CNS (group A).

Monitoring of cortical blood flow: clinical relevance of experimental laser Doppler studies

Continuous monitoring of cortical blood flow provides real time information of CBF-changes during neurosurgical operations and on the neurointensive care unit. Laser Doppler flowmetry is a continuous, noninvasive technique suitable for measurement of the cortical microcirculation. In a number of experimental studies we have analyzed the characteristics of this method for cortical blood flow monitoring. The high spatial resolution of laser Doppler flowmetry and the heterogeneity of the cortical microvascular network results in a scatter of flow values over a wide range depending on the site of measurement. Data collection from different spots and calculation of frequency histogram may serve as a measure of cortical blood flow. For clinical application instead of single fiber probes a multispot measurement approach will provide a reliable cortical blood flow monitoring. The use of continuous techniques will lead to a better understanding of cerebral hemodynamics under pathological conditions.

Alterations of regional cerebral blood flow and oxygen saturation in a rat sinus-vein thrombosis model

BACKGROUND AND PURPOSE

The pathophysiology of sinus-vein thrombosis (SVT) in patients and experimental animals is still poorly understood. This study was designed to examine and further elucidate the pathophysiological sequence of events, especially the relationship between local and regional blood flow and hemoglobin oxygen saturation (HbSO2) detected at identical locations. The use of both parameters as outcome indicators should be compared.

METHODS

SVT was induced by ligation of the superior sagittal sinus (SSS) and slow injection of kaolin-cephalin suspension into the SSS in rats. Regional cerebral blood flow (rCBF) was assessed by laser-Doppler flowmetry together with regional HbSO2, which was measured by a microspectrophotometric technique at 48 identical locations for 90 minutes after SVT using a scanning technique. Fluorescence angiography was performed before and 30 and 90 minutes after SVT induction. After 48 hours the animals were killed for histology.

RESULTS

The fluorescence angiographic findings could divide animals into three groups: (1) group A, with a solitary SSS thrombus (n=8); (2) group B, with a thrombosis of SSS and cortical veins (n=10); (3) group C, animals that had undergone sham operation (n=5). Decreases of rCBF and HbSO2 and brain damage were seen in group B but not in group A. The reduction of local HbSO2 preceded the flow decrease after sagittal sinus ligation but before thrombosis. Blood pressure in group A was found to be significantly higher after SVT than in groups B and C.

CONCLUSIONS

The brain with acute extension of thrombus from the SSS into cortical veins experiences a critically reduced supply of blood and oxygen. CBF, local HbSO2, and repeated angiography can be helpful monitors for the early detection of critical conditions after SVT. Local HbSO2 has a greater sensitivity to predict outcome than lCBF. Moreover, therapies directed to improve perfusion pressure or reduce vascular resistance may open further therapeutic windows during SVT progression.

[Reperfusion shock after occlusion of the superior mesenteric artery and accumulation of leukocytes within the wall of the small intestine]

The epithelial damage and the accumulation of the leucocytes within intestinal wall layers after ischemia and reperfusion was investigated in a pig model. Superior mesenteric artery (SMA) was occluded for 1 h (group 2, n = 9), 2 h (group 3, n = 6) and 3 h (group 4, n = 7) with a consecutive 2 h reperfusion period. The histological evaluation was performed on hematoxylin-eosine and Naphtol AS-D chloracetate stained preparations. The intensity of reperfusion shock depended on the duration of the intestinal ischemia. After 1 h SMA occlusion systolic blood pressure stabilized at a lower level with a normalization of the serum lactate level and the intestinal intramural pHi within the reperfusion period. After 2 h SMA occlusion the decrease of the systolic blood pressure was intensified (54-69 mm Hg) with a persistent elevated serum lactate concentration and a delayed increase of the ischemic pHi values. Reperfusion after 3 h SMA occlusion caused an irreversible shock. The epithelial damage also depended on the duration of the SMA occlusion. There were no significant changes of the leucocytic accumulation within the submucosa. But a significant increase of the number of the leucocytes was seen within the inner and the outer layer of the muscularis after 1 h SMA occlusion (106+/-5/mm2 resp. 280/mm2; p<0.05). This increase was less pronounced after 2 h (92+/-5/mm2*resp. 189+/-4/mm2; *p<0.05) and 3 h of SMA occlusion (84+/-5/mm2 resp. 185+/-23/mm2). Intestinal ischemia and reperfusion caused no changes of the leucocytic accumulation within the submucosa but a significantly increased accumulation within the muscularis after 1 h SMA occlusion, which was not seen after a more elongated occlusion period. A reperfusion shock without normalization of the serum lactate level and the intramural pHi suggesting intestinal perfusion disturbances may also lead to a depression of the leucocytic accumulation within the muscularis.

"Small volume resuscitation" as treatment of cerebral blood flow disturbances and increased ICP in trauma and ischemia

"Small volume resuscitation" (SVR) is a promising concept for the treatment of shock and trauma patients. SVR utilizes the fast infusion of a small volume of hypertonic saline to mobilize intraendothelial and parenchymal water to expand and restitute intravascular volume. Therefore it seems warranted to also consider SVR for the treatment of disturbances of the cerebral circulation and of increased intracranial pressure (ICP). The current study uses a rabbit model of global cerebral ischemia combined with mild hemorrhage to test SVR. Somatosensory evoked potentials (SEPs) serve as a short-term outcome parameter. The data demonstrate a beneficial effect treatment with hypertonic/hyperoncotic saline/hydroxyethylstarch as compared to volume replacement with starch or blood.

Pruritogenic effects of mitogen-stimulated peripheral blood mononuclear cells in atopic eczema

The etiology of atopic pruritus is unclear and seems mostly histamine-independent. In order to investigate non-mast cells as possible sources of pruritogenic agents, peripheral blood mononuclear cells from 12 atopic eczema patients and 12 controls were incubated in vitro for 24 h with phytohemagglutinin or concanavalin A (both at 10 micrograms/ml) or with medium alone, and each subject was tested with his own cell supernatants and lysates by prick testing and by application on tape-stripped skin. Histamine (0.1%) and substance P (500 microM) were tested in comparison, and reactions were observed for up to 24 h. Cell supernatants were also analysed for their contents of several cytokines. Lymphocyte cell extracts or supernatants failed to cause symptoms in controls but induced whealing in 6 and itching in 3 patients on prick testing within 5 min, lasting for 30 min in 2 patients and persisting for 6 h in 1 patient. Histamine caused itching in all controls and in 7 patients within 5 min on prick testing, with decreasing reactivity at later times. Substance P yielded results with lower values. With all three types of test reagents, fewer subjects reacted on tape stripped skin. High levels of interleukins 2 and 6, low levels of interferon and no detectable levels of interleukin 4 and tumour necrosis factor were measured in stimulated cell supernatants and extracts, with even lower levels in subjects exhibiting skin reactivity. These findings thus provide evidence that as yet unidentified mononuclear cell products may be involved in whealing and itching associated with atopic eczema.

Transcranial Doppler and cortical microcirculation at increased intracranial pressure and during the Cushing response: an experimental study on rabbits

The effect of increased intracranial pressure on the flow velocity of the basilar artery was measured with transcranial ultrasonic Doppler in New Zealand White rabbits under alpha-chloralose anesthesia and artificial respiration. Laser Doppler flowmetry served to study changes of the cortical microcirculation. The results confirm a high inverse correlation of the diastolic flow velocity, the pulsatility index, and the resistance index with the cerebral perfusion pressure (CPP). During acute intracranial hypertension, however, these parameters do not show a good correlation with the local cortical blood flow. The absence of a correlation was evident over a wide CPP range down to values of 35 mm Hg. Only at CPP values below this critical threshold is the microcirculation impaired. The threshold is reached at pulsatility index values of more than 2.0 and at resistance index values of more than 0.8. Therefore, transcranial Doppler indices permit the detection of critical reductions of microcirculatory blood flow. The Cushing reaction occurred with a constant time lag of 5.5 +/- 0.7 seconds after the loss of CPP. The Cushing reaction did not establish systolic blood flow, which remained below the functional threshold, as concluded from the temporary loss of somatosensory evoked potentials.

On the number of measurements necessary to assess regional cerebral blood flow by local laser Doppler recordings: a simulation study with data from 45 rabbits

Laser Doppler fluxmetry may improve the monitoring of cortical blood flow in neurosurgical patients. So far, however, the variability of laser Doppler readings found in the cerebral cortex has prevented a consequent usage of the technique in clinical practice. The current report analyzes the regional variability of laser Doppler readings from experimental animals. Typical frequency histograms of observed flow values display non-Gaussian distributions. A simulation technique is used to assess the number of measuring sites required for valid estimates of regional cortical flow. From a total of 990 local flow measurements from 45 rabbits random samples of sizes between 5 and 100 were repeatedly drawn to estimate the variability of median flow thus determined. The study underlines that small sample sizes below n = 20 are associated with a large variability (95th percentile: +38%) which decreases in a biphasic manner. Sample sizes above n = 25 are necessary to obtain more reliable information on regional cerebral blood flow: the 95th percentiles remain between 24 and 28% up to n = 45, and are still at 15% with n = 99.

Cerebral blood flow autoregulation during hypobaric hypotension assessed by laser Doppler scanning

Hypobaric hypotension was used to reduce systemic blood pressure in rats below the lower threshold of CBF autoregulation to evaluate a new laser Doppler (LD) "scanning" technique. Spontaneously breathing male Wistar Kyoto rats (n = 8) were anesthetized with chloral hydrate and the head fixed in a stereotaxic head holder. A cranial window with intact dura mater was introduced to assess local CBF (lCBF) by LD. One stationary probe served to detect rapid flow changes, whereas the second probe was used to sample lCBF recordings from many cortical locations by means of a stepping motor-controlled micromanipulator to obtain lCBF frequency histograms. Advantages are an improved spatial resolution together with the easy detection of low-flow areas and a better comparison of data from individual experiments. Arterial blood pressure was stepwise reduced by exposing the lower body portions to subatmospheric pressures (hypobaric hypotension), thus avoiding the use of drugs or heparinization. The lower threshold of CBF autoregulation was detected by "scanning" at arterial pressures between 50 and 46 mm Hg, with low-flow spots occurring immediately. The data suggest LD scanning as a method suited particularly for studies where lCBF inhomogeneities are expected, e.g., the ischemic penumbra or sinus vein thrombosis.

Relation of early Photofrin uptake to photodynamically induced phototoxicity and changes of cell volume in different cell lines

For efficacy of photodynamic therapy, selective uptake and retention of photoactive substances has been postulated. Therefore, measurements were performed to find out whether the photosensitiser Photofrin is taken up differently in malignant and non-malignant cells in vitro. In addition, the sensitivity of malignant cells and non-malignant cells to photodynamic exposure was investigated, by quantifying viability and volume alterations of the cells. Bovine aortic endothelial cells, mouse fibroblasts and amelanotic hamster melanoma cells were suspended in a specially designed incubation chamber under controlled conditions (e.g. pH, pO2, pCO2 and temperature). After establishing constant baseline conditions, the cellular fluorescence intensity per cell volume, indicative of the uptake of Photofrin, and cell volume were assessed by flow cytometry, and cell viability was quantified by the trypan blue exclusion test. Photodynamic exposure of cells was performed using an argon-pumped dye laser system via a 600 microns optical fibre at energy density of 4 Joules at the cell surface (40 mW/cm2, 100 s). In comparison to endothelial and fibroblast cells, the melanoma cells exhibited no increased uptake of Photofrin, and no enhanced sensitivity to photodynamic therapy (PDT). However, the fluorescence intensity/volume of endothelial cells was two to three times higher at each concentration of the photosensitiser. Following PDT, reduction in cell viability was dependent on the concentration of Photofrin, and directly correlated with fluorescence intensity per cell volume. In addition, the cells of all three lines, treated by PDT, revealed dose-dependent changes in cell volume. Melanoma cells exhibited the most excessive increase. It is suggested that selective uptake of photosensitiser in vitro is not characteristic for tumour cells. The high uptake of Photofrin by endothelial cells may indicate that the vascular endothelium is a major target for PDT, leading to cessation of tumour blood flow and subsequent destruction of tumour tissue. In addition, PDT-induced swelling of tumour cells might represent and effect synergistically impairing tumour perfusion, and thereby promoting tumour death.

An in vitro model to study cellular photosensitizer uptake and photodynamic dose-response relationships of tumor cells

Cellular fluorescence intensity (CFI) after incubation with varying concentrations of the photosensitizer Photofrin and the photodynamically induced dose-response relationships of hamster melanoma cells (A-MEL-3) were studied in a recently developed in vitro model. After administration of Photofrin to the extracellular serum-free medium, CFI was evaluated by flow cytometry together with constantly fluorescing latex particles used as a reference. After 5 min, 50% of maximal CFI was found, and after 60 min CFI was maximal. No further increase was obtained during the exposure to Photofrin over the incubation period of 4 h. During this plateau phase, CFI was significantly related to the concentration of Photofrin in the extracellular medium (r = 0.94; P < 0.001). Subsequent to increasing intervals of Photofrin exposure, cells were irradiated with laser light at 630 nm (40 mW/cm2, 4J). Cell viability as evaluated by trypan blue exclusion was significantly decreased with increasing concentrations of Photofrin in the medium, and significantly correlated with CFI during the plateau phase. After photodynamic treatment (PDT) cell fluorescence was reduced by about 15%. This was neither dose- nor time-dependent. On the basis of these findings we propose that CFI indicates photosensitizer uptake. This is also supported by the relation between CFI and phototoxicity. The latter also suggests that CFI might be useful to predict the PDT in vivo efficacy by this in vitro model. Besides measurements of photosensitizer uptake and cell photoxicity, the model demonstrates an excellent opportunity to study the molecular mechanisms of action associated with PDT.

Kinetics of Photofrin II in perifocal brain edema

Photodynamic therapy is under intense investigation as a possible adjuvant for the treatment of malignant tumors of the central nervous system. It relies on the fact that photosensitizers are selectively taken up or retained by malignant tissue. However, most brain tumors are accompanied by substantial vasogenic edema as a consequence of blood-brain barrier disruption within the tumor, leading to extravasation and propagation of plasma constituents into the surrounding brain tissue. Systemically administered photosensitizers may enter healthy tissue together with the edema fluid, possibly leading to sensitization of tissues outside the tumor. To test this hypothesis, vasogenic edema was induced by cold injury to the cortex in rats. The edema thus obtained is highly reproducible and very similar to tumor-associated edema. Just after injury induction, Photofrin II (PF-II), a commonly used photosensitizing agent, was administered at a dose of 5 mg per kilogram of body weight along with fluorescein isothiocyanate (FITC)-labeled albumin to mark edema advancement. After 1, 4, 12, or 24 hours, the brains were removed and frozen, and cryosections were studied with high-sensitivity video fluorescence microscopy for edema extravasation within the lesion and propagation of PF-II into the surrounding gray matter. PF-II advanced with edema along the corpus callosum underlying the cortex to a distance of 5 mm from the lesion after 4 hours. With the exception of the lesion, PF-II fluorescence returned to baseline after 24 hours, indicating subsequent washout. Propagation was comparable to the spreading of FITC-marked albumin. The authors conclude that photosensitizers spread with edema, an observation that may be pertinent to a number of questions concerning photodynamic therapy of cerebral tumors.

Cytologic and histologic changes in irradiated loops of transplanted small bowel

The histopathologic and cytopathologic changes in irradiated transplanted loops of bowel were assessed in 10 dogs. Five received conventional radiotherapy (CRT), and five received hyperfractionated doses of radiotherapy (HFRT) over the same period. Both groups exhibited identical cytologic findings, including blunting of villi and significant crypt atypia that could be mistaken for malignancy. Histologic examination corroborated the cytologic findings. At the end of the experiment two of the dogs that received CRT had developed strictures. One showed extensive submucosal fibrosis, while the other showed submucosal atrophy.

Cerebral blood flow alterations in a rat model of cerebral sinus thrombosis

BACKGROUND AND PURPOSE

Outcome from sinus vein thrombosis is very variable, with symptoms from headache to coma. Experimental findings suggest that an involvement of cortical veins is necessary to affect the cerebral microcirculation. Laser Doppler flowmetry was used to investigate the regional and temporal changes in local cortical blood flow after experimental occlusion and thrombosis of the superior sagittal sinus and tributary cortical veins in rats.

METHODS

Thrombosis was induced by slow injection of kaolin-cephalin suspension after frontal and caudal ligation of the sagittal sinus in rats. Local cerebral blood flow was measured by laser Doppler flowmetry and correlated with parenchymal damage found 24 hours after induction of thrombosis.

RESULTS

Local cerebral blood flow 1 hour after sinus occlusion and induction of thrombosis had decreased to 60.92 +/- 29.05% (p < 0.01); however, there was a large variability among individual animals. Only five of 12 rats showed histological damage and intracerebral hemorrhages 24 hours after induction of thrombosis. A subgroup analysis revealed that parenchymal damage occurred in concurrence with reduced blood flow values after sinus ligation and injection of the thrombogenic material. Sinus thrombosis alone, without alteration of blood flow, did not cause tissue necrosis.

CONCLUSIONS

The data support the contention that sinus vein thrombosis evolves gradually, with major symptoms occurring only if the thrombus expands from the sinus into bridging and cortical veins. Collateral venous outflow pathways are thereby occluded, and local blood flow may become reduced to and below the ischemic threshold.

Involvement of the central nervous system in renal hypertension

Involvement of the central nervous system (CNS) is a major complication of renal hypertension and is usually due to hypertensive encephalopathy. During a 17-year period we observed 25 children with renal hypertension associated with CNS manifestations in the absence of (group A) and 33 in the presence of advanced renal failure (group B). Convulsions were the most important symptom (65% in both groups combined). Other manifestations were reduced consciousness (69%), visual disturbances (28%), hemiplegia (14%), and cranial nerve palsy (10%). In 56% of children in group A, hypertension was recognised only after appearance of CNS symptoms. Three patients in group A and 19 in group B died. Intracranial haemorrhage associated with hemiplegia was found in 3 cases. From 1970-1977 to 1978-1986 the number of patients and the mortality in group B declined dramatically, probably as a result of improved antihypertensive and renal replacement therapy. In contrast, in group A the number of patients and of CNS symptoms remained similar. The study underlines the importance of frequent blood pressure monitoring in presence of acute or chronic renal disease.

Measles cervicitis. Report of a case with cytologic and molecular biologic analysis

We report on a 20-year-old woman who, in her third month of pregnancy, presented with a morbilliform rash, fever and diarrhea. Many multinucleate superficial, intermediate and metaplastic cells were noted in the cervical cytologic preparation. The presence of the measles virus in cells from the cervix was confirmed by the amplification of measles complementary DNA (cDNA) by the polymerase chain reaction. The patient's cervical Papanicolaou smear was unremarkable on reexamination four months after the onset of the disease. To our knowledge, this is the first verified reported case of infection of the uterine cervix by the measles virus.

Occlusion of the pig superior sagittal sinus, bridging and cortical veins: multistep evolution of sinus-vein thrombosis

Cerebral sinus-vein thrombosis may lead to severe hemodynamic changes, elevated intracranial pressure (ICP), and brain edema. It is supposed that progression of the thrombus from the sinus into bridging and cortical veins plays a key role in the development of these pathophysiological changes, but this hypothesis lacks experimental proof. The aim of this study, using a novel animal model of sinus-vein thrombosis, was to evaluate the effects of a standardized occlusion of the superior sagittal sinus and its bridging and cortical veins on hemodynamic alterations, on brain water content, and on ICP in domestic pigs. In 10 animals, the middle third of the superior sagittal sinus was occluded with a catheter-guided balloon. Five of these pigs received an additional injection of 1 ml fibrin glue into the superior sagittal sinus anterior to the inflated balloon, leading to an obstruction of bridging and cortical veins. In five control animals the balloon was inserted but not inflated. Five pigs underwent cerebral angiography. Four hours after occlusion, the brains were frozen in liquid nitrogen, and coronal slices were examined for Evans blue dye extravasation, regional water content, and histological changes. Occlusion of the superior sagittal sinus alone did not affect ICP or cerebral perfusion pressure (CPP). The additional injection of fibrin glue caused an obstruction of cortical and bridging veins as well as severe increases in mean (+/- standard deviation) ICP to 49.4 +/- 14.3 mm Hg, compared with 8.3 +/- 4.5 mm Hg in sham-treated controls and 7.1 +/- 3.9 mm Hg in animals with occlusion of the superior sagittal sinus alone. There was also a steep fall in the mean CPP to 34.2 +/- 19.6 mm Hg compared with 96.4 +/- 13.8 mm Hg in the control group. White-matter water content anterior to the occlusion site was elevated to 81.9 +/- 3.7 gm/100 gm frozen weight in the fibrin group as compared to 70.7 +/- 2.2 gm/100 gm in controls. Posterior to the occlusion site, water content did not differ among the three groups. Angiography demonstrated collateral flow via cortical and bridging veins in animals with occlusion of the superior sagittal sinus alone. Additional fibrin glue obstructed these collateral vessels. The data suggest a multistep process of pathophysiological alterations in patients with sinus-vein thrombosis and may explain why these patients present with a wide variety of symptoms: minor neurological deficits or headache might indicate thrombosis of the superior sagittal sinus and/or its bridging veins.(ABSTRACT TRUNCATED AT 400 WORDS)

Correlation of the Papanicolaou smear and human papillomavirus type in women with biopsy-proven cervical squamous intraepithelial lesions

The authors correlated Papanicolaou smear diagnoses with the presence of human papillomavirus (HPV) as determined by in situ hybridization in concurrent biopsy-proven cervical squamous intraepithelial lesions (SILs) in 132 women. Infection by HPV 6 or 11 was associated with a simultaneous normal Papanicolaou smear in 4 of 29 (14%) cases. This result was significantly greater (P less than 0.05) than that found in cases of infection by an oncogenic HPV type (types 16, 31, 33, 35, and others), in which the rate of a concurrent normal Papanicolaou smear was 5 of 88 (5%). Infection by one of these oncogenic types was associated with a Papanicolaou smear diagnostic of SIL in 55 of 88 (63%) cases, whereas infection by HPV 6 or 11 was associated with a Papanicolaou smear diagnostic of SIL significantly (P less than 0.05) less frequently (6 of 29, 18%). It is concluded that, for women with SILs, the likelihood of a Papanicolaou smear diagnostic of the lesion is greater for women with HPV types of known oncogenic potential.

Determination of the rate of DNA synthesis of human tumor cells obtained by fine needle aspiration. Comparison of flow cytometry and an immunoperoxidase method for the detection of thymidine analogue incorporation

Two methods of detecting thymidine analogue incorporation by lymphoma, leukemia and myeloma cells obtained by fine needle aspiration (FNA) are described. In one method, cells which have been incubated with the thymidine analogue iododeoxyuridine (IDURD) were exposed to primary monoclonal anti-IDURD antibody and a fluorescein-labeled linking antibody. The fluorescence of the antibody-labeled cells, which had synthesized DNA and incorporated the analogue, was detected by flow cytometry (FCM). In a second method, the cells that incorporated the analogue were detected on glass slide Cytospin preparations by an immunoperoxidase (IP) technique. The IDURD labeling index (LI), as determined by both FCM and IP staining, was compared to the percentage of cycling (S + G2/M) cells as determined by acridine-orange FCM. The data indicate that the IP method is reliable and correlated strongly with FCM determination of LI, percentage S-phase and lymphoma grade. Given the low cost and wide availability of IP technology, the IP method may be desirable for laboratories wishing to supplement cytology reports with cell cycle data.

[Microcirculatory effects of photodynamic therapy with hematoporphyrin derivative]

Hematoporphyrin derivative photosensitizes selectively malignant tumors following intravenous administration and shows typical fluorescence patterns in the range between 630 nm and 690 nm. Irradiation with laser light (630 nm) causes selective tumor necrosis due to a phototoxic effect. The site of action of this "photodynamic treatment (PDT)" remains obscure. In this study it could be demonstrated that directly after PDT a selective haemorrhage and thrombosis of blood vessels occurs in the tumor tissue. Furthermore, the arterioles of the surrounding normal tissue constrict completely. Venules of normal tissue showed slow thrombosis. Basically, the result of photodynamic treatment was a complete breakdown of tumor tissue microcirculation accompanied by partial damage to the surrounding normal tissue perfusion. This evaluation of the impact of PDT on tumor microcirculation led to the conclusion that a primary site of action of photodynamic therapy may contribute to the selective destruction of tumor microcirculation.

Spinal metastasis of a thyroglobulin-rich Hürthle cell carcinoma detected by fine needle aspiration. Light and electron microscopic study of an unusual case

A prospective diagnosis of metastatic thyroid carcinoma was made on an aspirate of a spinal mass. While the cellular component of the aspirate was compatible with a renal or hepatic neoplasm, the recognition of colloid on air-dried smears defined the cells as Hürthle cells. Biopsy of the spinal tumor and subsequent thyroidectomy revealed a Hürthle cell carcinoma. Whereas the primary tumor showed typical Hürthle cell architecture, with solid tumor nests and microfollicle formation, the metastasis contained areas of macrofollicle formation with abundant colloid production and strong immunocytochemical reactivity for thyroglobulin. This change of histologic pattern from the primary tumor to the metastasis has not been previously reported in Hürthle cell lesions. The unusual light microscopic and ultrastructural aspects of this tumor are discussed.

Fine needle aspiration cytology of thymolipoma. A case report

A case of thymolipoma in a 14-year-old girl diagnosed prospectively by fine needle aspiration (FNA) biopsy is reported. The cellular constituents of the aspirate, lymphocytes and epithelial cells, were characterized by routine cytology and immunocytochemistry. Although primarily based on the FNA cytology, the diagnosis was supported by the patient's clinical history and the radiographic demonstration of a fat density mass. This appears to be the first description of thymolipoma in a fine needle aspirate.

Hepatoblastoma presenting as isosexual precocity. The clinical importance of histologic and serologic parameters

A 2-year-old boy presented with sexual precocity secondary to a hormone-producing hepatoblastoma. The tumor demonstrated an aggressive histologic pattern and stained immunohistochemically for alpha-fetoprotein and beta-subunit human chorionic gonadotrophin. After a successful liver transplant these tumor markers were closely followed. We conclude that histologic subclassification of hepatoblastoma is most useful for predicting likelihood of resectability. Tumors with predominantly fetal-type histology tend to be better circumscribed and are more likely to be resectable with improved survival relative to tumors with predominantly embryonal histology. The presence or absence of mesenchymal elements does not seem to have prognostic importance. Anaplastic features predict a poor outcome, but it remains for these to be uniformly defined and applied. Small uniform cellular histology with neuroblastoma-like differentiation appears to be particularly ominous. Serologic tumor markers, especially alpha-fetoprotein (AFP) and human chorionic gonadotrophin (HCG) are useful as monitors of potential tumor recurrence, but their efficacy is compromised by the unpredictable variation of tumor cell metabolism, undoubtedly a result of the genetic instability and heterogeneity of proliferating malignant cells.

Aspiration of the breast and nipple discharge cytology

Between 1 January 1974 and 30 June 1984, 1,003 specimens obtained from the breast were submitted for cytologic evaluation to the Department of Pathology at the Waterbury Hospital Health Center. Eighty-eight per cent were obtained by fine needle aspiration of a palpable mass; the remainder were smears of nipple discharges. Precytologic and postcytologic clinical data were available for 80 per cent of the specimens. In the fine needle aspiration group, there were 219 instances of proved carcinomas; 79 per cent of these had either positive or suspicious cytologic findings. Seventy-five per cent of the patients with positive cytologic results underwent mastectomy without prior histologic confirmation of the needle aspiration and all were confirmed as malignant growths. There were 41 false-negative aspirates which were reviewed in detail. The cytologic slides of 24 of the 41 false-negative aspirates were available for re-evaluation by a second, independent cytopathologist. Only one was thought to have been misread initially; the remainder appeared to have been falsely negative for technical reasons related to aspiration or fixation technique or tumor size less than 1 centimeter. There was one false-positive finding in a patient who was found to have fat necrosis at biopsy. Results of nipple discharge cytology were less accurate. Positive or suspicious cytology was found in only five of 11 proved instances of carcinomas. There was one false-positive and five false-negative results in this group. We conclude that needle aspiration of palpable masses of the breast is an accurate, cost effective procedure which is readily adaptable to a community hospital, provided that a pathologist with an interest in cytology is available.

Carcinomatous meningitis as the initial manifestation of breast cancer

Report is made of an elderly woman in whom carcinomatous meningitis was the initial manifestation of breast cancer. The patient presented with nonfocal neurologic symptoms. Cytologic examination of cerebrospinal fluid (CSF) revealed malignant cells arranged either in loose clusters or as isolated single cells. The morphology of the cells, some of which had a signet-ring configuration with a crescent-shaped nucleus as well as prominent round nucleoli, suggested a breast primary, which was proven by subsequent histologic study.

Cushing's syndrome secondary to ectopic cortisol production by an ovarian carcinoma

A 35-yr-old woman had Cushing's syndrome, amenorrhea, and elevated and nonsuppressible levels of urinary and plasma cortisol and urinary 17-hydroxycorticosteroids. An ovarian carcinoma with extensive metastases was found. Tumor concentrations of ACTH were much lower than those in any previously reported patient with the ectopic ACTH syndrome. Cortisol levels obtained from the venous effluent of tumor-involved ovaries were higher than that in peripheral plasma obtained at the same time. Transient postoperative normalization of plasma and urinary cortisol followed partial tumor removal. Electron microscopic study of the tumor revealed a cell type consistent with steroid-secreting cells. Postmortem examination revealed atrophy of both adrenal glands and no pituitary adenoma.