DNA damage evaluation of hydroxyapatite on fibroblast cell L929 using the single cell gel electrophoresis assay.

Hydroxyapatite is the main component of the bone which is a potential biomaterial substance that can be applied in orthopaedics. In this study, the biocompatibility of this biomaterial was assessed using an in vitro technique. The cytotoxicity and genotoxicity effect of HA2 and HA3 against L929 fibroblast cell was evaluated using the MTT Assay and Alkaline Comet Assay respectively. Both HA2 and HA3 compound showed low cytotoxicity effect as determined using MTT Assay. Cells viability following 72 hours incubation at maximum concentration of both HA2 and HA3 (200 mg/ml) were 75.3 +/- 8.8% and 86.7 +/- 13.1% respectively. However, the cytotoxicity effect of ZnSO4.7H2O as a positive control showed an IC50 values of 46 mg/ml (160 microM). On the other hand, both HA2 and HA3 compound showed a slight genotoxicity effect as determined using the Alkaline Comet Assay following incubation at the concentration 200 mg/ml for 72 hours. This assay has been widely used in genetic toxicology to detect DNA strand breaks and alkali-labile site. The percentage of the cells with DNA damage for both substance was 27.7 +/- 1.3% and 15.6 +/- 1.0% for HA2 and HA3 respectively. Incubation of the cells for 24 hours with 38 microg/ml (IC25) of positive control showed an increase in percentage of cells with DNA damage (67.5 +/- 0.7%). In conclusion, our study indicated that both hydroxyapatite compounds showed a good biocompatibility in fibroblast cells.

Anesthesia for Cesarean section and posterior fossa craniotomy in a patient with von Hippel-Lindau disease.

PURPOSE: To describe the care of a pregnant woman with von Hippel-Lindau disease (VHLD) and intracranial mass lesions. CLINICAL FEATURES: A 30-yr-old primigravida with VHLD at 35 weeks gestation was seen at the obstetric anesthesia clinic because she wished an epidural analgesia during labour. She had a history of headaches and dizziness. Further investigations showed an enlarged cerebellar hemangioblastoma with significant local mass effects. A combined Cesarean section delivery and posterior fossa craniotomy was performed at 37 weeks gestation. A general anesthetic with fentanyl, rocuronium, nitrous oxide, oxygen and isoflurane was given for Cesarean section delivery. After delivery, isoflurane was reduced and propofol infusion at 4-8 mg x kg(-1) x hr(-1) was initiated. The patient had an uneventful operative course and recovery. CONCLUSIONS: Patients with VHLD may have worsening of preexisting lesions or develop other lesions during pregnancy. Some asymptomatic lesions can increase the risk for anesthesia complications. These patients need comprehensive assessment before administration of anesthesia.

Prolonged epidural infusions of ropivacaine (2 mg/mL) after colonic surgery: the impact of adding fentanyl.

UNLABELLED: We evaluated the safety and efficacy of a 72-h epidural infusion of ropivacaine and measured the impact of adding fentanyl 2 microg/mL to the required infusion rate, on the quality of postoperative pain relief and the incidence of side effects, after colonic surgery. One hundred fifty-five patients scheduled for elective colonic surgery were randomized in this trial. Epidural infusions of ropivacaine 2 mg/mL with fentanyl 2 microg/mL (R + F) and without fentanyl (R) were commenced during surgery and continued for 72 h postoperatively. This was a prospective, randomized, double-blinded, multi-center trial. The median infusion rate required was less in the R + F group (9.3 vs 11.5 mL/h, P < 0.001). Median pain scores at rest and on coughing were lower in the R + F group (P < 0.0001). The incidence of hypotension was more in the R + F group (P = 0.01). Time to readiness for discharge was delayed in the R + F group (median 6.6 vs 5.5 days, P = 0.012). The addition of fentanyl to ropivacaine resulted in decreased infusion rates and enhanced pain control; however, adverse effects were increased and readiness to discharge was delayed. IMPLICATIONS: Epidural infusions of ropivacaine with and without fentanyl were administered to patients to control pain after colonic surgery. Patients who received ropivacaine with fentanyl had better pain control, increased side effects, and delayed readiness to discharge. This study questions the value of adding opioids to epidural infusions of local anesthetics.

Continuous epidural ropivacaine 0.2% for analgesia after lower abdominal surgery.

The purpose of this study was to determine whether a lumbar epidural infusion of ropivacaine 0.2% would provide effective analgesia with an acceptably low incidence of motor blockade and side effects after lower abdominal surgery. After combined general and epidural anesthesia and surgery, 125 patients were randomly assigned to receive either saline or ropivacaine 0.2% at a rate of 6, 8, 10, 12, or 14 mL/h (Groups R6, R8, R10, R12, and R14, respectively) for 21 h. Supplemental analgesia, if required, was provided with intravenous patient-controlled analgesia with morphine. Data were collected at 4, 8, and 21 h, and included morphine consumption, pain scores at rest and with coughing, motor and sensory block, and adverse events. Cumulative morphine consumption was less in Groups R10, R12, and R14 compared with the saline group. At 4 h analgesia was better among patients receiving ropivacaine, but at 21 h pain scores were identical. Sensory blockade at 8 and 21 h was greater in the ropivacaine groups compared with the saline group. Approximately 30% of R8, R10, and R12 patients, and 63% of R14 patients had demonstrable motor block of the lower limbs at 21 hours. We conclude that lumbar epidural ropivacaine 0.2% reduces parenteral morphine requirements but has little effect on pain scores and may be associated with motor blockade.

Effects of anion exchange on intracellular pH and tension in basilar artery of dogs.

We simultaneously measured intracellular pH (pHi) and isometric tension in canine basilar arteries. pHi was calculated from the ratio of fluorescence intensities at 540 nm of exciting wavelengths of 500 and 440 nm in the presence of 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF). pHi was 7.33 +/- 0.02 in Krebs-Henseleit solution (pH of 7.4 at 37 degrees C). Application of the anion exchange blocker 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) decreased the resting pHi by 0.25 pH units. Increasing extracellular pH (pHo) [by decreasing CO2 tension (PCO2)] from 7.4 to 7.8 increased pHi by 0.38 pH units and increased tension by 2.28 +/- 0.21 mN. Decreasing pHo from 7.8 to 7.4 (by increasing PCO2) restored the pHi and muscle tension to their baseline levels. SITS inhibited the increase in pHi and isometric tension in response to the increase in pHo in an endothelium-independent fashion. The Na+/H+ exchange blockers, amiloride or 5-(N-methyl-N-guanidinocarbonylmethyl)-amiloride, did not affect the pHo or tension changes. The results suggest that in the range of pH tested, anion exchange is more important than Na+/H+ exchange in the regulation of pHi and mechanical tone in the basilar artery.

Spinal anaesthesia for Caesarean section in a patient with a cervical arteriovenous malformation.

PURPOSE: Arteriovenous malformations (AVM) of the spinal cord are rare. We report the successful management of a patient with a cervical spinal cord AVM undergoing Caesarean section delivery, using a spinal anaesthetic. CLINICAL FEATURES: Based on previous radiological investigations, the patient was known to have an AVM at the third cervical level of her spinal cord. After application of monitors and intravenous administration of 1 L normal saline, a 25 g Whitacre needle was inserted into the subarachnoid space at the L3-4 interspace. Spinal anaesthesia was established with a solution consisting of hyperbaric spinal bupivacaine 12 mg, fentanyl 12.5 micrograms and epidural morphine 0.25 mg. There was no neurological deficit during hospital stay or after discharge. CONCLUSION: The safe outcome of spinal anaesthesia for our patient is encouraging. The presence of spinal cord AVM at the cervical region is not an absolute contraindication to spinal anaesthesia.

Failure of meperidine wound infiltration to reduce pain after laparoscopic tubal ligation.

Many women experience considerable pain and delay in return to regular activity after laparoscopic tubal ligation. We performed a prospective randomized double-blind study to evaluate pain and recovery after laparoscopic tubal ligation and the influence of meperidine wound infiltration. After approval by the Ethics Committee, informed consent was obtained from 60 patients. All patients received naproxen 500 mg po one hour before surgery. Patients were randomized into three groups. All patients received a standard general anaesthetic. Group C patients (n = 18) received normal saline (NS) in the deltoid and NS in the wound. Group S patients (n = 21) received 50 mg of meperidine in the deltoid and NS in the wound. Group W patients (n = 21) received 50 mg meperidine in the wound and NS in the deltoid. After surgery, pain and nausea were treated with morphine and metoclopramide as needed. Following hospital discharge, patients were contacted by telephone daily until they returned to regular activities. The mean maximum pain score of Group S patients was lower than that of Group C patients (P < 0.05). Group S patients required less morphine in the Postanaesthesia Care Unit than the Group C patients (P < 0.05). One Group C patient was readmitted to hospital due to inadequate analgesia with oral medications. Group S patients returned to regular activity earlier than the Group C patients (P < 0.05). It is concluded that wound infiltration with meperidine did not affect postoperative pain or recovery. Intramuscular administration of the same amount of meperidine resulted in less postoperative pain and earlier return to regular activity.

Comparison of sprinkle versus syrup formulations of valproate for bioavailability, tolerance, and preference.

We compared a new coated-particle formulation of valproate (Depakote Sprinkle) capsules with valproic acid (Depakene) syrup for bioavailability, side effects, and patient and parent preference. Twelve children with epilepsy, aged 5 to 16 years, participated in this randomized, two-period, crossover study. They were assigned to a 7-day regimen with one formulation and then crossed over to the other; the drug was given every 12 hours. On day 7, blood samples collected during a 12-hour period were analyzed for the presence of valproate. At the study's end, parents and children were asked structured questions regarding formulation preference and adverse events. The extent of absorption from sprinkle equaled that from syrup (relative bioavailability = 1.02), but absorption was slower (time to maximum concentration = 4.2 vs 0.9 hour; p less than 0.01). Fluctuations in serum concentrations were less with sprinkle (34.8% vs 62.3%; p less than 0.01). Sprinkle was preferred by 9 of the 12 parents because of east of administration, and by nine of the children because of improved palatability. We conclude that sprinkle may be substituted for syrup without changing the daily dose. Furthermore, sprinkle, because of its prolonged absorption, may be given every 12 hours to children receiving monotherapy. Compliance may be enhanced because of the more convenient dosing schedules and the high degree of patient and parent acceptance.

Mechanism of hypoxia-induced alteration in cerebral arteriolar tone in rats.

We studied the changes in pial arteriolar diameter during hypoxia and 60 and 120 min after restoration of normoxia, using the closed cranial window technique in artificially ventilated and normocapnic rats. Pial arteriolar diameter increased 16 +/- 4% during hypoxia (PaO2 less than 25 mm Hg, lasting 10 min). Although blood pressure (BP), heart rate (HR), and blood gases returned to prehypoxic level when measured at 60 and 120 min after hypoxia, pial arterial diameter decreased significantly (13 +/- 5 and 16 +/- 6% below control levels, respectively). This posthypoxic vasoconstriction was reversed by treatment of the brain surface with L-660,711 (10(-5) M), a specific leukotriene D4 receptor antagonist. These data suggest that leukotrienes may be involved in delayed cerebral vasoconstriction that follows a brief period of hypoxia.

Possible role of leukotrienes in hypoxic contraction of canine isolated basilar artery.

1. Hypoxia reversibly increased isometric tension in unstimulated canine isolated basilar artery rings. 2. Nordihydroguaiaretic acid (NDGA; 5 x 10(-6) M), an inhibitor of lipoxygenase and quinacrine (10(-5) M), which blocks the release of arachidonic acid from phospholipids by inhibiting the enzyme phospholipase A2, blocked hypoxia-induced contractions. 3. The preferential leukotriene D4 (LTD4) antagonist, L-660,711, also inhibited the hypoxia-induced contractions in concentrations ranging from 10(-8) M to 10(-5) M. The effects seen were statistically significant (P less than 0.05). Two components of inhibition were seen. 4. Arachidonic acid (5 micrograms ml-1) caused contraction of the isolated basilar artery rings. This response was inhibited by NDGA (5 x 10(-6) M) and L-660,711 (10(-5) M). 5. The LTD4 (10(-8) M-10(-7) M)-induced contraction was relaxed by L-660,711 in a dose-dependent manner. Both the contraction caused by LTD4 as well as that caused by hypoxia were relaxed by 5 x 10(-6) M adenosine. 6. Leukotriene(s) may be involved in hypoxia-induced contraction of canine isolated basilar artery. However, they may not be the sole mediator(s).

Inhibition of the acetylcholine-induced relaxation of canine isolated basilar artery by potassium-conductance blockers.

Canine basilar artery rings precontracted with 5-hydroxytryptamine (0.1-0.5 microM) relaxed in the presence of acetylcholine (25-100 microM), sodium nitroprusside (0.1 microM), or stimulation of the electrogenic sodium pump by restoration of extracellular K+ (4.5 mM) after K(+)-deprivation. Acetylcholine-induced relaxation is believed to be caused by the release of endothelium-derived relaxing factor (EDRF) and is prevented by mechanical removal of the endothelium, while relaxations induced by sodium nitroprusside or restarting of the sodium pump are endothelium-independent. Acetylcholine-induced relaxation was selectively blocked by pretreatment of the tissue with the nonselective K+ conductance inhibitors, 4-aminopyridine (4-AP, 3 mM), Ba2+ (1 mM), and tetraethylammonium (20 mM), 4-AP also blocked ACh-mediated relaxation in muscles contracted with elevated external K+. Relaxation of 5-hydroxytryptamine-induced contraction by sodium nitroprusside, or by addition of K+ to K(+)-deprived muscle, was not affected by 4-AP. Relaxation of basilar artery with acidified sodium nitrite solution (containing nitric oxide) was reduced by 4-AP. These results suggest that 4-AP and possibly Ba2+ inhibit acetylcholine-induced endothelium-dependent relaxation by inhibition of the action of EDRF on the smooth muscle rather than through inhibition of release of EDRF. The increase in K+ conductance involved in acetylcholine-induced relaxation is not due to ATP-inhibited K+ channels, as it is not blocked by glyburide (10(-6) M). Endothelium-derived relaxant factor(s) may relax smooth muscle by mode(s) of action different from that of sodium nitroprusside or by hyperpolarization due to the electrogenic sodium pumping.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamics after hemorrhage during acute ethanol intoxication in newborn piglets.

Hemodynamic alterations after hemorrhage were investigated using the microsphere technique in nitrous oxide-anesthetized 2-day-old piglets after acute ethanol intoxication (1.4 g/kg). After hemorrhage (20 ml/kg), mean arterial blood pressure decreased by 34% (p less than 0.01), cardiac output decreased by 58% (p less than 0.01), and systemic vascular resistance increased by 87% (p less than 0.01). In nonintoxicated piglets subjected to hemorrhage, mean arterial blood pressure decreased 17% (p less than 0.01) while alterations in cardiac output and systemic vascular resistance were not significant. Intoxicated piglets had delayed heart rate increases of 11% (p less than 0.01) while heart rate in nonintoxicated piglets increased 27% (p less than 0.01) immediately after hemorrhage. After hemorrhage, arterial perfusion to the liver, kidneys, gastrointestinal organs, and carcass was decreased in intoxicated piglets but only gastrointestinal and carcass perfusion were reduced in nonintoxicated piglets. In summary, acute ethanol intoxication significantly impaired the newborn piglet's cardiovascular response to moderate hypovolemia and delayed the onset of a compensatory tachycardia response. Such cardiovascular impairments may be extremely detrimental to neonates.

Intracellular pH measurement with fluorescent dye in canine basilar arteries.

The intracellular pH (pHi) of basilar artery rings was determined with 2',7'-bis-(carboxyethyl)-5,(6)-carboxyfluorescein (BCECF) by measuring the ratio of emitted (540 nm) fluorescence intensities (FI) at excitation wavelengths of 500 and 440 nm. There was a dye loss from the rings in 90 min (39.3 +/- 3.6%, p less than 0.001). We found that the ratio of fluorescence intensities does not adequately correct for dye loss; hence, we derived a method to correct for dye loss during pHi determinations. Calibration curves of the ratio versus pHi were constructed for the artery rings. The slope and intercept of the calibration curves depended on FI440. Linear regression lines for the slope and intercept versus FI440 were: [formula; see text] In solutions with different pH and different concentrations of free BCECF, the slope of the ratio versus pH of the solution was steeper at high concentrations of BCECF. Thus, pHi was calculated from a calibration curve in which the slope and intercept were determined from FI440 with the above formula. The corrected pHi was 7.37 +/- 0.05 (n = 25) at pHo 7.4 and 37 degrees C.

Haemodynamic alterations in anaesthetized and acutely intoxicated newborn piglets.

1. We investigated the haemodynamic alterations in 2-day old anaesthetized piglets after acute ethanol intoxication using the microsphere technique. 2. After ethanol infusion, mean arterial blood pressure (MABP) decreased by 6%, cardiac output (CO) decreased by 26%, heart rate (HR) increased by 20% and systemic vascular resistance (SVR) increased by 36%. 3. Arterial perfusion to the kidneys, gastrointestinal (GI) organs and carcass decreased by 39%, 34% and 26%, respectively. 4. In piglets pretreated with 4-methylpyrazole (4-MP), an alcohol dehydrogenase inhibitor, the decrease in MABP and increase in HR were not observed after ethanol infusion, but the reduction in CO and increase in SVR were maintained. 5. Arterial blood flow to the GI organs and carcass, but not the kidneys, remained at significantly reduced levels. 6. These observations indicate that ethanol can adversely affect CO and arterial perfusion to GI and musculoskeletal structures while metabolites of ethanol, such as acetaldehyde, affect MABP and HR. Therefore, the clinical effects observed after acute ethanol intoxication in neonates may vary with their rate of ethanol metabolism.

Impaired epidural analgesia after dural puncture with and without subsequent blood patch.

We carried out a retrospective assessment of epidural analgesia in 46 parturients who had a previous dural puncture. Of 29 women who had both dural puncture and blood patch previously, only 59% had an uncomplicated successful second epidural anesthetic. Of 17 parturients who had dural puncture but no blood patch previously, only 65% had an uncomplicated successful subsequent epidural anesthetic. In comparable groups of parturients without previous dural puncture, 88%-92% had successful epidural analgesia. The data suggest that dural puncture may lead to impaired epidural analgesia subsequently. Epidural blood patch after dural puncture did not lead to any further decrease in the rate of good analgesia with subsequent epidural anesthetics. Parturients who request epidural analgesia and who have had previous dural puncture with or without blood patch should be informed about the 35%-40% chance of poor epidural analgesia.

Kinetic disposition of ethanol in the neonatal piglet and hemodynamic effects in the presence and absence of 4-methylpyrazole.

The hemodynamic effects of acute ethanol intoxication and the kinetic disposition of ethanol are reported for the first time in neonatal piglets under nitrous oxide anesthesia. Two hours after a single dose of ethanol (1.4 g/kg), blood pressure decreased from 76 +/- 4 to 71 +/- 4 mm Hg (p less than 0.05) and heart rate increased from 194 +/- 10 to 227 +/- 8 beats/min (p less than 0.05; means +/- SE). By 5 hr, blood pressure dropped to 67.5 +/- 4 mm Hg and heart rate increased to 239 +/- 8 beats/min. In piglets pretreated with 4-methylpyrazole, an alcohol dehydrogenase inhibitor, there was a transient increase in blood pressure (p less than 0.05) and a decrease in heart rate (p less than 0.05) immediately after the end of the ethanol infusion. However, the hemodynamic alterations observed 2 hr after ethanol treatment alone were prevented with 4-methylpyrazole. These findings indicate that ethanol metabolites play a significant role in hemodynamic alterations observed after acute ethanol intoxication. The mean ethanol metabolic rate derived from plasma data was 94 +/- 9 mg/liter/hr. This corresponded to an apparent Km of 68 +/- 3 mg/liter and a Vm of 123 +/- 11 mg/liter/hr. The Vd was 0.966 +/- 0.031 liter/kg. The metabolic rate for ethanol, derived from plasma data, correlated with in vitro alcohol dehydrogenase activity at pH 7.4 and 25 and 37 degrees C. The optimum pH for hepatic alcohol dehydrogenase activity was 9.9.

Ouabain prevents loss of autoregulation in rat pial arterioles caused by reoxygenation after a brief hypoxic episode.

Pial arteriolar diameter changes inversely with changes in systemic arterial blood pressure. Such changes are consistent with autoregulatory functions. These responses are reduced by a brief period of hypoxia followed by reoxygenation. By using an open cranial window preparation we assessed the changes in pial arteriolar diameters during blood pressure changes in rats induced by hemorrhage and reinfusion of blood, before and after a brief period of hypoxia. The slopes of the changes in pial arteriolar diameter as a function of mean arterial blood pressure were -0.47 +/- 0.26 micron/mmHg (mean +/- SD; 1 mmHg = 133.3 Pa) before hypoxia and -0.11 +/- 0.23 micron/mmHg after hypoxia in the untreated rats. In ouabain-treated rats, corresponding slopes were -0.42 +/- 0.24 and -0.46 +/- 0.22 micron/mmHg. The observed protective effects of ouabain might be a blockade of the Na-K pump in the sarcolemma of the vascular smooth muscle.