Cerebrospinal Fluid from Subarachnoid Haemorrhage Patients Causes Excessive Oxidative Metabolism Compared to Vascular Smooth Muscle Force Generation

Summary  Cerebrospinal fluid (CSF) from subarachnoid haemorrhage (SAH) patients can stimulate vascular smooth muscle to generate force in vitro. CSF from SAH patients suffering from delayed ischaemic neurological deficits due to cerebral vasospasm can generate near maximal force in vitro and previous experiments have ascribed this generation of force to be a calcium mediated event. The intracellular calcium concentration has been demonstrated to rise during the vasospastic process. Calcium also stimulates oxidative metabolism as does adenosine diphosphate (ADP), the product of adenosine triphosphate (ATP) hydrolysis. Significant alteration in high energy metabolites such as ATP, ADP and phosphocreatine have also been demonstrated in various models of SAH mediated vasospasm. Vascular smooth muscle predominantly uses oxidative metabolism for force generation and reserves glycolytic metabolism for ion homeostasis. A decrease in oxidative metabolism during force generation would imply failing mitochondria and increased glycolytic high-energy phosphate supply. Increased oxidative metabolism would imply a decreased efficiency of the contractile apparatus or mitochondria.  The aim of this study was to see if SAH CSF stimulation of porcine carotid artery oxidative metabolism was altered during force generation when compared with incremental calcium stimulation with potassium chloride depolarisation. CSF from patients (n=10) who had subarachnoid haemorrhage stimulated force generation but with a significant `right shift' in oxygen consumption. This `right shift' is indicative of an increased energy cost for contractile work. These results suggest that vascular smooth muscle contractile apparatus, when stimulated by subarachnoid cerebrospinal fluid, is consuming excess adenosine triphosphate during force generation.     

Cerebral Blood Flow and Oxygen Metabolism During Mild Hypothermia in Patients with Subarachnoid Haemorrhage

Cerebral blood flow and O2 metabolism during hypothermia (33-34 degrees C) was evaluated in 5 patients with aneurysmal subarachnoid haemorrhage by positron emission tomography (PET). Their preoperative clinical condition was WFNS scale IV or V. The patients received surface cooling postoperatively, and were maintained in a hypothermic state during transfer for radiological examination. Positron emission tomography revealed a decrease in cerebral blood flow and O2 metabolic rate. Cerebral blood flow was 34.8+/-15.1 ml/100 ml/min and the O2 metabolic rate was 1.85+/-0.61 ml/100 ml/min in areas of the middle cerebral artery ipsilateral to the ruptured aneurysms, whereas these values were 30.8+/-7.1 and 2.21+/-0.45 ml/100 ml/min, respectively, on the contralateral side. This represents a decrease of 37+/-27% compared to normal cerebral blood flow and 52+/-16% compared to normal O2 metabolic rate (p < 0.02) in the ipsilateral areas, and decreases of 44+/-13% and 43+/-12%, respectively, on the contralateral side. The present results reflected the luxury perfusion state in almost all cases and provide the first PET evidence of decreased cerebral blood flow and metabolic rate of O2 during hypothermia in humans.     

Reversal of Cerebral Vasospasm by the Nitric Oxide Donor SNAP in an Experimental Model of Subarachnoid Haemorrhage

The constant release of nitric oxide (NO) is essential to maintain basal cerebrovascular tone. Oxyhaemoglobin, liberated by lysis of red blood cells after subarachnoid haemorrhage binds NO and prevents its entry into vascular smooth muscle cells. While endothelium-dependent vasoconstriction is preserved, decreased levels of NO inhibit endothelium-dependent relaxation and may cause vasospasm. S-nitrosothiols are potent vasodilators and precursors of NO. The authors' aim was to determine whether S-nitroso-N-acetylpenicillamine (SNAP), a stable S-nitrosothiol compound, could reverse vasospasm in an experimental vasospasm model in rabbit. Experimental subarachnoid haemorrhage (SAH) was induced in 37 New Zealand white rabbits. The animals were divided into four groups. Control (no SAH), SAH only, SAH plus saline and SAH plus SNAP. SNAP (15 micrograms/kg/min) or 0.09% saline (equal volume) was infused 46 hours after induction of SAH. All animals were killed by perfusion fixation 48 hours after SAH occurred. Basilar arteries were removed, sectioned and their cross sectional areas were evaluated in a blind manner, by light microscopy and by using computer assisted morphometry. Experimental SAH elicited vasospasm in all animals of SAH only and SAH plus saline group. In animals treated with SNAP, arterial narrowing was markedly attenuated without producing systemic hypotension. This widening achieved statistical significance when compared to the arteries of the SAH only and SAH plus saline group (p < 0.01). This study indicates that the NO donor SNAP is a potentially useful drug to reverse cerebral vasospasm due to SAH.     

Plasma and Cerebrospinal Fluid Endogenous Digoxin-Like Immunoreactivity in Patients with Aneurysmal Subarachnoid Haemorrhage

Summary  Recent evidence indicates the presence of naturally occurring digitalis-like compounds in mammals, collectively known as either digitalis-like (DLF) or ouabain-like (OLF) factors, presumed to be endogenous hormones regulating the biological activity of the NA⁺/K⁺-ATPase and its isoforms. This substance has been postulated to enhance renal tubular sodium excretion and to increase peripheral vascular resistance. Digoxin-like immunoreactive substance (DLIS) was observed in plasma of some patients with spontaneous subarachnoid haemorrhage (SSAH). Accumulating evidence suggests the central nervous system as a site of synthesis, but also as a site of hypertensinogenic action of endogenous cardioglycosides. The present study intends to establish the ratio of the DLIS in plasma to that in cerebrospinal fluid (CSF) in patients with SSAH and to investigate possible connection of this substance with development of arterial vasospasm. A prospective analysis of DLIS levels was performed on plasma and CSF samples obtained in 40 patients who had suffered a recent SSAH. DLIS levels were determined by the fluorescence polarisation immuno-assay method immediately after the admission to the Ward, and again seven days later. The comparison of CSF and plasma DLIS levels did not show statistically significant differences between the results – neither for the first (Z=0.530; P=0.591) nor for the seventh day after the disease onset (Z=0.448; P=0.654). Three possible hypothetical explanations of these results are offered: a) substance determined by digoxin immuno-assay has no essential likeness to digoxin; b) loss of the haemato-encephalic barrier integrity enabling free substance exchange between plasma and central nervous system; c) digoxin-like substance production within the central nervous system. Further, comparison of DLIS plasma levels (7^th day from onset of SSAH) with angiography results showed that patients with multiple vasospasm had essentially higher plasma DLIS levels compared to patients with no vasospasms (Z=2.59; P=0.0097). The amount of extravasated blood, assessed on the basis of cranial CT scanning, was also connected with higher plasma DLIS levels (X²=3.29; P=0.0305). The enhanced arterial narrowing which occurs in SSAH may be in part mediated by increased digitalis-like factor activity.     

Obligatory Roles of Protein Kinase C and Nitric Oxide in the Regulation of Cerebral Vascular Tone: An Implication of a Pathogenesis of Vasospasm After Subarachnoid Haemorrhage

Summary  We previously showed that a canine basilar artery manifested tonic and potent, protein kinase C (PKC)-dependent contractions when nitric oxide (NO) was inhibited. We also reported a linear correlation between chronological changes in the angiographic severity of vasospasm, enhanced PKC, and attenuated guanosine, 13′,15′-cyclic monophosphate (cGMP) activity in a canine subarachnoid haemorrhage model. The activity of cGMP is an indicator of NO-function. Based on this evidence, we have hypothesized that PKC and NO regulate cerebral vascular tone. We particularly focused on the role of NO in a negative feedback mechanism on PKC activity in the maintenance of vascular tone. To further confirm our hypothesis, we investigated the effect of PKC down-regulation on the tonic vascular contraction induced by NO-inhibition.  Canine basilar artery was used in the experiment. Significant down-regulation of PKC activity in vascular smooth muscle cells was obtained by incubation with 10⁻⁵ mole/L of phorbol 12-myristate 13-acetate (PMA) for 24 hours. The tonic and potent contraction induced by NO-inhibition was completely suppressed in the PKC down-regulated artery, even though the artery manifested a significant contraction in high-K⁺ solutions. These results indicate an obligatory role of PKC activity in tonic contraction when NO is inhibited, and support our previous data. Nitric oxide induces vascular relaxation by inhibiting PKC activity. Subarachnoid haemorrhage impairs this inhibition, resulting in PKC-dependent vascular contraction, such as vasospasm.     

Thrombin Activity in CSF after SAH is Correlated with the Degree of SAH, the Persistence of Subarachnoid Clot and the Development of Vasospasm

Summary  We previously reported that the coagulation system in cerebrospinal fluid (CSF) is strongly activated in the early stage of a subarachnoid haemorrhage (SAH). We evaluated the relationship among thrombin activity, degree of SAH, amount of clearance of SAH, and vasospasm. The CSF levels of fibrinopeptide A (FPA) were measured by radio-immunoassay in 36 SAH patients, who were diagnosed by computerized tomography (CT) within 12 hours and on whom surgery was performed within 48 hours. Clearance of SAH (%) was evaluated as the size of the clot in the basal cistern visualized between the initial and postoperative CT. The mean level of FPA in the patients of Group 3 (Fisher's CT classification) (182.2 ng/ml) was significantly higher than those in the patients of Group 2 (36.2 ng/ml). There was a significant difference in the mean level of FPA between patients with (47.6 ng/ml) and without infarction (408.3 ng/ml). In 18 of the 27 patients of Group 3 for whom the clearance of the SAH was determined, the patients showing a lower clearance rate (<50%) of SAH demonstrated a significantly higher rate of infarction and a significantly higher level of FPA (466.6 ng/ml) than did the patients with a higher clearance rate (>50%) of SAH (79.2 ng/ml). These results suggest that, the thrombin activity in CSF is correlated with the degree of SAH, the persistence of subarachnoid clot and the development of vasospasm.     

Experimental Study of Intracisternal Administration of Tissue-Type Plasminogen Activator Followed by Cerebrospinal Fluid Drainage in the Ultra-Early Stage of Subarachnoid Haemorrhage

This experimental study evaluated the effect of intrathecal injection of tissue-type plasminogen activator followed by cisternal drainage in the ultra-early stage of aneurysmal subarachnoid haemorrhage to prevent vasospasm. Twenty Japanese white rabbits were divided into five groups. Either tPA (groups A, B, and E) or saline (groups C and D) was injected intrathecally 1 hour (groups A, B, C, and D) or 21 hours (group E) after the intrathecal injection of blood. Cerebrospinal fluid was drained 2, 4, and 6 hours after the intrathecal injection of blood (groups A, C, and E). On day 4, the angiographic caliber of the basilar artery in each group was as follows (mean +/- SD): A, 85.9 +/- 5.0%; B, 74.6 +/- 5.3%; C, 69.1 +/- 2.7%; D, 64.0 +/- 4.9%; E, 80.2 +/- 2.7% (compared with baseline). In the two groups in which CSF was drained (groups A and C), fibrinolysis with tPA significantly suppressed vasospasm. In the two groups treated with tPA (groups A and B), cisternal drainage significantly suppressed vasospasm. In the two groups treated with saline (groups C and D), however, cisternal drainage did not suppress vasospasm. Examination of the series of CSF samples (groups A and C) showed that fibrinolysis with tPA effectively cleared clots early. In the two groups treated with tPA and CSF drainage (groups A and E), early removal of subarachnoid clots reduced the degree of vasospasm. Early fibrinolysis with tPA and early removal of subarachnoid clots by drainage is effective for preventing vasospasm.     

Systemic and Cerebral Haemodynamics During Craniotomy Under Mild Hypothermia in Patients with Acute Subarachnoid Haemorrhage

Summary ? Background. Mild hypothermia provides cerebral protection against ischaemic insults in various animal models. We compared systemic and cerebral oxygenation between mild hypothermic and normothermic management in 60 patients with acute subarachnoid haemorrhage who underwent clipping of cerebral aneurysms.  Method. The temperature in the pulmonary artery was maintained at 36°C in 28 patients and was reduced to 34°C in 32 patients. Parameters in the systemic and cerebral haemodynamics from pulmonary artery and internal jugular vein catheters were compared between the two groups immediately after the induction of anaesthesia (T1), and just before temporary occlusion or aneurysm clipping (T2).  Findings. Cardiac index, oxygen delivery index, oxygen consumption index, and oxygen saturation of the jugular bulb were significantly lower at T2 in hypothermic group (H) (2.9±0.6 L/min/m², 400.8±106.3 ml/min·m², 87.0±14.8 ml/min·m², 55.2±6.6%, respectively) than in normothermic group (N) (3.7±0.6, 521.0±105.5, 109.9±21.7, 60.9±6.6) (p<0.05). The arterial lactate and arteriojugular difference in oxygen content were significantly higher in H (2.3±1.3 mmol/L, 6.5±1.5 ml/dl, respectively) than in N (1.7±1.0, 5.6±1.2) (p<0.05). Arteriojugular differences in carbon dioxide tension and hydrogen ion content were significantly lower at T2 in H (−10.8±2.1 mm Hg, −6.4±1.3 nmol/L, respectively) than in N (−8.9±2.8, −5.3±1.0) (p<0.05).  Interpretation. The balance between oxygen supply and demand systemically and in the brain may worsen during aneurysm surgery for patients with acute subarachnoid haemorrhage under mild hypothermia. Oxygenation of the brain and the whole body should be monitored closely during this surgery, and adequate circulatory assistance is recommended under mild hypothermia.     

The Influence of Vascular Pressure and Angiographic Characteristics on Haemorrhage from Arteriovenous Malformations

Summary ? Background. The present study was designed to determine whether there is a physiological explanation for the predisposition of patients with certain angiographic characteristics to haemorrhage from cerebral arteriovenous malformations (AVMs).  Methods. Intra-operative measurement of feeding artery pressure (FAP) and intravascular pressures in the draining venous system [draining vein pressure (DVP) and cranial sinus pressure (SP)] were performed for 30 AVM cases using direct puncture of the vessels. The correlation between pressures and previously described angiographic characteristics predisposing to haemorrhage were evaluated.  Findings. Small nidus size and only one draining vein increased the risk of haemorrhage. FAP and DVP are both inversely related to the number of draining veins and the size of the AVMs. DVP was significantly higher in AVMs with haemorrhage (23.1±8.7 mmHg) than in those without (13.5±4.4), as was FAP (58.6±12.8 as opposed to 38.7±4.7) (p<0.05). Moreover, the difference between systemic blood pressure and the FAP with haemorrhagic AVMs (17.0±9.5 mmHg) was significantly lower than that in nonhaemorrhagic cases (33.7±5.5) (p<0.05). The pressure difference between the feeding artery and draining vein was not significant between the haemorrhagic and nonhaemorrhagic groups. There was no significant difference of SP between haemorrhagic and nonhaemorrhagic patients.  Interpretation. The present study suggests that a high DVP probably induced by high resistance in the venous drainage system, as well as a high FAP, may contribute to the development of haemorrhage from AVMs, and physiologically supports previous reports that small AVMs and AVMs with only one draining vein are susceptible to haemorrhage.     

Reversal of Radiographically Impending Stroke with Multiple Intraarterial Papaverine Infusions in Severe Diffuse Cerebral Vasospasm Induced by Subarachnoid Hemorrhage

Summary. Background: Selective intraarterial infusion of papaverine is used in the treatment of symptomatic cerebral vasospasm induced by aneurysmal subarachnoid hemorrhage (SAH). Delays in instituting therapy for vasospasm can lead to irreversible cerebral infarction and a devastating outcome. Endovascular papaverine treatment of vasospasm in the presence of low-attenuation lesions on computed tomography (CT) is controversial, because of the fear of reperfusion hemorrhage in completed infarcts. Method: Two patients with aneurysmal SAH who subsequently developed severe diffuse vasospasm were identified. In both patients, large areas of low-attenuation change suggesting impending cerebral infarction were seen on CT scans. The patients received multiple infusions of intraarterial papaverine in an effort to treat vasospasm refractory to medical management. Findings: After multiple intermittent administrations of papaverine, which initially appeared to increase the low-attenuation changes, there was dramatic reversal of the radiographic findings. There was also improvement in circulation time, transcranial Doppler velocities, and clinical outcome. Interpretation: These findings suggest that in some patients, intraarterial infusions of papaverine initiated in the earliest stages of ischemia may exacerbate the radiographic appearance of low-attenuation changes, but may ultimately reverse the evolution of cerebral infarction.     

The Relationship Between Cerebral Blood Flow Velocities and the Amount of Blood Clots in Computed Tomography After Subarachnoid Haemorrhage

127 patients with aneurysmal subarachnoid haemorrhage (SAH) were analyzed for the relationship between the amount of blood clots as detected by initial computed tomography (CT) up to 48 hours after SAH and changes of blood flow velocities as measured using transcranial Doppler ultrasonography (TCD). All patients were operated on within 72 hours after SAH. Patients who presented with remarkable brain oedema or with pathological intracranial pressure (ICP) due to mass effects of a haematoma, and who were in a poor neurological condition classified according to Hunt-Hess as grade V were excluded from this study. Serial TCD examination of the middle cerebral arteries (MCA) and anterior cerebral arteries (ACA) started within 48 hours after SAH and were performed daily up to three weeks. A statistically significant correlation between blood load designated according to Fisher's grading as group CT I-CT IV and mean flow velocities (MFV) was found in groups CT I, II, and III. High values of MFV in MCA examinations were noted in patients with severe SAH (group CT III)--161 cm/s, and low values in patients without SAH (group CT I)--119 cm/s. Patients with haematocephalus and/or haematoma without a mass effect (group CT IV) had lower blood flow velocities than patients with severe SAH (group CT III) but values were higher than in patients without SAH (group CT I). The number of days for which MFV in the MCA was > 120 cm/s and was statistically (p < 0.05) correlated with the amount of blood clots as observed in the respective CT (in group CT I, II, and III). MFV values in the anterior cerebral artery (ACA) were lower than those obtained in the middle cerebral artery (MCA) in all groups. Statistically significant (p < 0.05) differences were noted between groups CT I and CT III (first and third week) and between groups CT I and CT IV (third week). If the SAH was extensive in the CT scan, pathological values of MFV > 90 cm/s were observed in ACA, and this was more pronounced in group CT III than in group CT IV. Blood flow velocities obtained via TCD were registered to compare side-to-side differences and particularly high differences were observed in patients with severe SAH. It is concluded that the amount of blood clots in the initial computed tomography after SAH is significantly correlated with cerebral blood flow velocity measurements by TCD.     

Advanced Oxidation Protein Products Induce Vascular Calcification by Promoting Osteoblastic Trans-Differentiation of Smooth Muscle Cells via Oxidative Stress and ERK Pathway

Vascular calcification is an actively regulated process similar to bone formation. Advanced oxidation protein products (AOPPs) have been demonstrated to be novel markers of oxidant-mediated protein damage. The present study investigated the role of AOPPs in inducing osteoblastic trans-differentiation and calcification of smooth muscle cells in vitro. We found that AOPPs directly increased the calcium deposition and expression of core binding factor-α1 (CBF-α1) and osteopontin (OPN) and significantly decreased SM-α-actin expression in human aortic smooth muscle cells (HASMCs). AOPPs increased intracellular oxidative stress, which was inhibited by vitamin E. Vitamin E also inhibited AOPP-induced calcium content and osteoblast differentiation of HASMCs. Furthermore, the inhibitor of ERK significantly suppressed the effects of AOPPs on calcification and osteoblast marker expression. These findings suggest that AOPPs induce vascular calcification by promoting osteoblast differentiation of smooth muscle cells via oxidative stress and ERK pathway.     

Effect of Long-Term Growth-Hormone Substitution Therapy on Bone Mineral Density and Parameters of Bone Metabolism in Adult Patients with Growth Hormone Deficiency

Reduced bone mineral density (BMD) and the prevalence for osteoporotic vertebral fractures are symptoms of growth hormone deficiency (GHD) syndrome, and GH replacement therapy is now available for GH-deficient adults. We investigated the long-term effects of GH replacement therapy on bone mineral density (BMD) and bone metabolism in 19 adult patients with GHD over a period of 18 months. In response to GH treatment, the initially decreased IGF-I concentrations rose significantly during 18 months of therapy to levels within the normal range (matched for sex and age) (mean change 158.1 ± 50.8 ng/ml, P < 0.001). Parameters of bone formation such as osteocalcin (OC) and procollagen I-C-Peptide (PICP) showed a significant increase in the first 6 months of therapy, followed by a slight decrease in the next months. Markers of bone resorption (Crosslaps^R and deoxypyridinoline (D-Pyr) also increased significantly with a peak value after 6 months and all parameters except PICP remained above baseline values after 18 months. BMD of the femoral neck (FN) showed an increase after 18 months of therapy (mean change 0.01 ± 0.03 g/cm² after 18 months, n.s.). However, the increase in BMD was significant only in the lumbar spine (LS) (mean change 0.03 ± 0.04 g/cm², P < 0.05 after 18 months). We conclude that GH replacement therapy in adult patients with GHD over a period of 18 months causes a pronounced increase in bone turnover mainly during the first 12 months of therapy and increases BMD of the lumbar spine and the femoral neck after 18 months. Received: 13 March 1997 / Accepted: 7 August 1997     

自拟活血止痛方治疗胫骨平台骨折对患者骨代谢及关节恢复情况的影响

目的:探讨自拟活血止痛方应用于胫骨平台骨折患者术后治疗的效果及对患者康复效果的影响。方法:选取2018 年4 月—2019 年8 月在本院接受手术治疗的70 例胫骨平台骨折患者,随机分为两组,对照组(35 例)给予甘露醇治疗,观察组(35 例)在对照组的基础上再加用自拟活血止痛方治疗,观察两组患者术后疼痛、骨代谢指标变化、关节功能恢复等情况。结果:观察组术后10 d 的肿胀程度为(1.30±0.10) cm,小于对照组的(1.98±0.42) cm,VAS 评分为(1.48±0.22)分,低于对照组的(1.97±0.38)分,差异有统计学意义(P ＜ 0.05);观察组术后消肿、止痛平均时间为(8.10±1.63)d、(5.30±1.03)d,均短于对照组的(9.86±2.13)d、(6.87±1.08)d,骨折愈合、完全负重平均时间分别为(90.10±13.74)d、(94.53±14.88)d,均显著短于对照组的(116.63±16.32)d、(112.45±14.45)d,差异有统计学意义(P ＜ 0.05);观察组术后6个月Lysholm 膝关节评分为(53.48±3.28)分,Merchant 量表总评分为(92.63±10.53)分,均高于对照组的(46.85±3.74)分、(80.84±11.62)分,差异有统计学意义(P ＜ 0.05);观察组术后6 个月的基质金属蛋白酶-2(MMP-2)、骨形态发生蛋白-2(BMP-2)、胰岛素样生长因子-1(IGF-1)水平分别为(679.03±60.73) ng/mL、(677.05±65.28) ng/mL、(204.84±24.74)ng/mL,均高于对照组的(580.84±58.74)ng/mL、(580.88±58.94)ng/mL、(184.72±26.62)ng/mL,差异均有统计学意义(P ＜ 0.05);观察组术后6 个月的并发症总发生率为5.71%,显著低于对照组的22.86%,差异有统计学意义(P ＜ 0.05)。结论:胫骨平台骨折患者术后加用自拟活血止痛方治疗,可有效减轻患者术后患肢肿痛及疼痛,改善骨代谢,提高关节功能,改善治疗效果。     

The Use of Cardiac Troponin-I (cTnI) to Determine the Incidence of Myocardial Ischemia and Injury in Patients with Aneurysmal and Presumed Aneurysmal Subarachnoid Hemorrhage

Summary A prospective single center study was performed to determine the minimal preoperative incidence of unrecognized cardiac injury in patients suffering aneurysmal and presumed aneurysmal subarachnoid hemorrhage (SAH). When caring for such patients in the pre- and post operative period clinicians must be aware of the possibility of cardiac injury even when a history of previous cardiac symptomatology is not present. Forty-seven consecutive patients suffering from SAH over a five-month period underwent serum measurements of the cardiac muscle marker troponin I (cTnI) immediately upon admission. Repeat studies, if possible, were done 24 hours later. EKG was performed in all patients and was available for review in 44 of the 47 cases. Echocardiography was performed in four of eight patients with elevated cTnI levels. Signs and symptoms relating to cardiac ischemia were recorded by the patients' physicians and nurses. Eight individuals (17%) had elevations in cardiac troponin I levels. Because surgical treatment is generally carried out as soon as possible following the hemorrhage, many patients with normal troponin I levels within twenty-four hours of their hemorrhage were operated upon before a repeat enzyme could be obtained or possibly before elevations could be recorded. In addition, a number of patients were referred to our center several days post-hemorrhage at a time when marker levels may have normalized. Therefore, the 17% incidence of elevated cTnI may be an underestimate. Only two of the eight patients had clinical abnormalities in cardiac function. Four patients with elevated levels had echocardiograms, three of which were abnormal. One additional patient died of a myocardial infarction before an echocardiogram could be obtained. EKG was abnormal in six of the seven patients with elevated troponin who had tracings available for review. Recordings consistent with recent myocardial ischemia were present in four of these. Of the 39 patients with negative troponin I levels, 37 had EKG available for review. None had recordings clearly consistent with recent myocardial ischemia although 13 were suggestive of ischemic changes. None of these 39 patients had pre- or post-operative clinical changes in cardiac function. Elevations in troponin I appeared to be unrelated to the patient's Hunt and Hess grade or Fisher score although our numbers were too small to draw any meaningful conclusions.     

The Effects of Serum from Patients with Acute Liver Failure on the Growth and Metabolism of Hep G2 Cells

In many bioartificial liver systems currently being designed and evaluated for use in fulminant hepatic failure, direct contact is required between the patient's blood and the liver cells in the device. The efficacy of such devices will be influenced by the interaction of fulminant hepatic failure (FHF) patient serum with the cells. We have found that FHF serum inhibits the growth rate and the synthesis of DNA, RNA, and protein; disturbs glutathione homeostasis; and induces morphological changes in cultured human Hep G2 cells. These interactions should influence the design of bioartificial liver devices based on proliferating cell lines and indicate the requirement to pretreat FHF patient plasma to reduce the toxin load.     

The Monitoring of ALA-Induced Protoporphyrin IX Accumulation and Clearance in Patients with Skin Lesions by In Vivo Surface-Detected Fluorescence Spectroscopy

The method of surface-detected fluorescence has been used to monitor the emission intensity from 5-aminolaevulinic acid (ALA)-induced protoporphyrin IX (PpIX) in lesions and corresponding adjacent normal skin. Three types of lesions were examined: psoriatic plaques, actinic keratosis and basal cell carcinoma. This study included a total of 14 human volunteers on whom ALA-induced PpIX formation and clearance was monitored for a total of 48 h post-ALA application. Both an ALA dose-ranging study, as well as a comparison of results between normal and lesional tissue at a fixed ALA dose, were carried out. For the dose range examined (10–30%), there was no ALA dose dependency of the PpIX fluorescence for any of the lesions tested. Although all three lesions tested did show enhanced PpIX fluorescence as compared with normal skin, there was considerable lesion-to-lesion variability. Thick psoriatic plaques seem to give longer PpIX retention times than those of thin lesions. Limitations of the surface-detected fluorescence methodology are discussed. Paper received 2 June 1997; accepted after revision 14 September 1998.     

The Microscopic Structure of Bone in Normal Children and Patients with Osteogenesis Imperfecta: A Survey Using Backscattered Electron Imaging

The microstructure of iliac crest biopsies from normal children or from those afflicted with osteogenesis imperfecta (OI) has not previously been studied to determine the tissue histology in the context of the degree of mineralization. The material in this study comprised 112 iliac crest biopsies from children aged 1.9–22.9 years. Fifty-eight were reference biopsies taken from children with no bone disease and the remainder were biopsies from children diagnosed as having OI (23 were Type I, 8 Type III, 18 Type IV, and 5 Type V). The specimens, which had been embedded in polymethylmethacrylate (PMMA), were micromilled and carbon coated to permit backscattered electron imaging. Reference biopsies from very young children often contained densely mineralized cartilage, and evidence of rapid cortical drift. Circumferential lamellae became a prominent feature after the toddler stage, and active remodeling and slower cortical drift continued through childhood. The biopsies from older teenagers and young adults were indistinguishable. Occasional mineralized osteocyte lacunae were detected in even the youngest children. Bone from children with OI Type I often appeared normal in microstructure and amount, but in some there was a dearth of bone and an abundance of osteocytes. Compared with age-matched controls, cortical and trabecular bone from children with OI Types III and IV were markedly sparse and very cellular, and primary osteonal systems continued to be formed later than expected. A distinguishing feature of the bone from OI Type V patients was the failure of patches of bone to mineralize, especially adjoining a reversal line. Packets of bone tissue exhibiting either considerably higher than normal or deficient mineralization would contribute to the characteristic trait of mechanical weakness. Received: 26 December 1997 / Accepted: 7 August 1998