Highly selective motor nerve block and movement analysis for preoperative evaluation of complex spastic gait

BACKGROUND

Lower-extremity spasticity and impaired gait control after central nervous system injury are challenging to improve, because spasticity limits residual motor control while providing mechanical support. Highly selective partial neurectomies (HSPNs) can substantially reduce spasticity but may have greater risks in patients with complex lower-extremity spastic gait.

OBJECTIVE

To examine the potential of ultrasound- and stimulation-guided highly selective motor nerve blocks (HSMNBs) to assess the potential impact of reduced spasticity on gait.

METHODS

In this retrospective series, six patients underwent HSMNBs with movement assessment before and after the block. Range of motion, strength, position angles, surface electromyography, lower limb kinematics, and patient satisfaction were assessed.

RESULTS

Pre- and post-HSMNB movement analysis yielded dichotomous gait kinematics, which facilitated surgical decisions. Of the 59 metrics evaluated, 82% demonstrated a positive improvement post-block (62% improved more than one standard deviation (SD) of typically developing means, 49% improved > 2 SD) and 16% demonstrated a negative change (2% worsened > 1 SD).

CONCLUSION

HSMNB provided clear efficacy in changing clinical, surface electromyography, and gait parameters. Movement analysis provided clear and robust objective and patient-centered evidence for surgical guidance. This protocol may provide utility in evaluation of patients being considered for HSPNs for complex spastic gait patterns.

Altered Serum Factor Vlll-Related Antigen (VIII: AGN)/von Willebrand Factor (VIII: vWf) in Haemophiliacs with Inhibitors to Factor VIII Procoagulant Activity (VIII: C)

Inhibitors to factor VIII (anti-F VIII) developing in patients with classic haemophilia have apparent specificity for the factor VIII procoagulant activity (VIII: C), rather than the factor VIII-related antigen (VIII :AGN) and von Willebrand factor (VIII :vWf) regions of the factor VIII complex.

Since procoagulant function is absent following in vitro clotting, but serum retains VIII: AGN/vWf properties, we searched for differences in VIII :AGN and VIII :vWf of inhibitor serum that might relate to the presence of anti-F VIII.

Rocket immunoelectrophoresis and the washed platelet ristocetin assay were performed on the plasma and serum of nine haemophiliacs with inhibitors, 23 non-inhibitor haemophiliacs and six normal subjects. Unlike normal and non-inhibitor haemophilic sera, that from five of nine inhibitor patients demonstrated absent VIII : vWf and significantly lower VIII: AGN (p <0.05). Furthermore, VIII: AGN of faster mobility was detected on crossed immunoelectrophoresis of the sera of three inhibitor patients. Thrombin clotting of plasma from haemophiliacs with high titer anti-F VIII was associated with a greater loss of VIII: vWf than seen with non-inhibitor haemophilic plasma. This effect was independent of the presence of platelets.

These data indicate that in vitro clotting is associated with alteration in the serum VIII: AGN/vWf of some haemophiliacs with anti-F VIII.

Intrathecal baclofen for postoperative analgesia after total knee arthroplasty

STUDY OBJECTIVE

To determine whether intrathecal baclofen is an effective adjunctive agent to decrease acute and chronic postoperative pain after total knee arthroplasty.

DESIGN

Prospective, randomized, double-blind controlled trial.

SETTING

Operating room and inpatient units of a university hospital.

PATIENTS

60 adult, ASA physical status I, II, and III patients presenting for total knee arthroplasty.

INTERVENTIONS

Anesthesia was provided by spinal injection of 15 mg of 0.75% hyperbaric bupivacaine combined with either 100 mcg baclofen or saline. Sedation was provided with intravenous midazolam and propofol.

MEASUREMENTS

Data were collected on adverse effects, opioid usage, and verbal pain scale (VPS) from 0 to 10. The study period was divided into six discrete time intervals that included the 1(st) 72-hour postoperative period and a three-month post-discharge follow-up telephone call.

MAIN RESULTS

The baclofen group used less morphine in the PACU than the control group (5 mg vs. 9.3 mg; P = 0.04). VPS were lower in the baclofen group than the treatment group, but significant differences could be demonstrated only in the time periods 48-72 hours and three months postoperatively. At three months, fewer patients in the baclofen group reported pain than the control group (8/27 vs. 19/29; P = 0.009). Regression analysis showed that the baclofen group was 4.5 times less likely to report pain at three months (95% CI: 1.5-16.6).

CONCLUSIONS

IT baclofen used as an adjuvant to spinal anesthesia for total knee arthroplasty allows for less postoperative opioid usage and less chronic pain at three months.

The Fastrach Intubating Laryngeal Mask Airway: an overview and update

PURPOSE

To provide an evidence-based overview and update on the use of the Fastrach Intubating Laryngeal Mask Airway (FT-LMA) when used within operative and non-operative settings.

PRINCIPAL FINDINGS

The FT-LMA is available in three sizes to provide ventilation and the ability to pass an endotracheal tube (ETT) into the trachea blindly, semi-blindly, or with indirect visualization for patients over 30 kg. The Chandy maneuver is recommended routinely; the first maneuver optimizes ventilation, and the second maneuver increases success at endotracheal intubation (ETI). The manufacturer's reinforced tube or a pre-warmed or reversed standard ETT may be utilized. Insertion and ventilation are successful in almost all patients. Blind ETI is highly successful; adjuncts are generally not necessary. The FT-LMA has a proven role in the airway management of anticipated difficult operating room (OR) intubations, unanticipated OR intubations, cervical spine injuries, and limited airway access situations. Literature in the pre-hospital and emergency department settings is limited but favourable. The FT-LMA has compared favourably with fibreoptic intubation, the LMA-Classic, the laryngeal tube, and the CobraPLA. Initially, the more expensive LMA CTrach appeared to be more successful, but overall it is not. The FT-LMA airway seal pressures are excellent; serious complications are uncommon, and the FT-LMA figures prominently in most difficult airway guidelines.

CONCLUSIONS

The FT-LMA has proven to be a useful difficult airway device both within and outside of the operating room. Effective ventilation is established in nearly all cases, and blind ETI is possible in the vast majority of cases if the optimal techniques described are used. Serious complications are uncommon.

Two-beam coupling between filament-forming beams in air

We experimentally demonstrate two-beam coupling between nearly identical filament-forming beams intersecting in air. A 7% amplification of one beam occurs at the energy expense of the other in a single interaction, controllable by adjusting their relative delay by tens of femtoseconds. The data are consistent with the impulsive Raman nonlinear response of the air molecules as the coupling mechanism. The filament conical emission is controllably enhanced or suppressed by the interaction, indicating that two-beam coupling may be an effective means for filament regeneration and control.

Detection, frequency and prediction of problems in the use of the proseal laryngeal mask airway in children

OBJECTIVES

Our objective was to assess the use of several tests of ProSeal LMA (PLMA) position and function that had been previously published but not studied in the pediatric population in a wide variety of clinical cases.

BACKGROUND

The PLMA is widely used in pediatric anesthesia practice but complication rates have only been studied in small series while tests of function suggested for adults have not been studied at all.

METHODS

We prospectively collected data, after placement of the PLMA by the digital method, on depth of insertion (DOI), 'suprasternal notch' test, 'chest pressure test', leak pressure, maximum minute ventilation (MMV), resting minute ventilation (RMV), success rate of insertion and success rate of passage of a gastric tube. Perioperative complication rates were recorded.

RESULTS

A total of 222 cases were analyzed, 47 were laparoscopic or open abdomen, 15 nonsupine. Ages were 2 months to 20 years and weight 5.4-116 kg. Two hundred seven (91%) were placed successfully at first attempt and 100% at third attempt. One hundred fifty-four of 156 (99%) gastric tubes were placed successfully. Four patients had signs of inadequate ventilation. All of these had MMV/RMV ratios <2. A total of nine had MMV/RMV ratio <2. Eight had DOI score < or =2.

CONCLUSIONS

The PLMA can be used in a large variety of cases with a high degree of success. Clinical tests described for adults, such as MMV/RMV ratio and DOI are also associated with complications in the pediatric population.

Arterial to endtidal carbon dioxide gradient during pediatric laparoscopic fundoplication

BACKGROUND

Discrepancies between arterial carbon dioxide (P(a)CO(2)) and endtidal carbon dioxide (ETCO(2)) measures have been demonstrated in ventilated children with cyanotic congenital heart disease, infants with respiratory failure and during visceral and urological laparoscopic surgery.

OBJECTIVES

Our objective was to assess the extent of the P(a)CO(2) to ETCO(2) gradient in children during laparoscopic fundoplication.

METHODS

We prospectively collected data on patient characteristics, surgical conditions, pH, ETCO(2)and P(a)CO(2) during laparoscopic fundoplication using carbon dioxide insufflation in children age <29 months.

RESULTS

Data were collected on nine cases, four cases aged <1 year. A P(a)-ETCO(2) gradient was present during insufflation. The gradient was larger in children age less than 1 year but statistically significantly different from a value of zero, only at t = 30 min (mean = 8 mmHg, sem = 0.81, P = 0.004) and t = 60 min (mean = 5 mmHg, sem = 1, P = 0.014). Minute ventilation was increased from 20% to 100% to control ETCO(2).

CONCLUSIONS

ETCO(2) may not accurately represent arterial values during laparoscopic fundoplication, especially in the infant when carbon dioxide insufflation is used. Consideration should be given to placing an arterial line for blood gas measurement in some patients.

Perioperative Complications of Adenotonsillectomy in Children with Obstructive Sleep Apnea Syndrome

We evaluated the rate of complications experienced by children who undergo adenotonsillectomy for obstructive sleep apnea syndrome (OSAS), the safety of a standard anesthetic protocol for these children, and preoperative predictors of complications. Sixty-one children with OSAS, confirmed by polysomnography, and 21 children with recurrent tonsillitis were anesthetized using a standard protocol before adenotonsillectomy (ages 2-16 yr, ASA 1-3). The number of complications and medical interventions in the perioperative period were recorded and correlated with the presence and severity of OSAS. Children with OSAS had more respiratory complications per operation than non-OSAS children (5.7 vs 2.9, P < 0.0001). Supraglottic obstruction, breath holding, and desaturation on anesthetic induction and emergence were the most common complications. Increased severity of OSAS, low weight, and young age are correlated with an increased rate of complications. Medical intervention was necessary in more children with OSAS during recovery and emergence than in the non-OSAS group (17/61 vs 1/21, P < 0.05). Both groups of children had similar opioid requirements and time to discharge from the recovery room. These findings suggest that children with OSAS are at risk for respiratory complications after adenotonsillectomy, but that these complications do not prolong the time to discharge.

A simple technique to reduce epistaxis and nasopharyngeal trauma during nasotracheal intubation in a child with factor IX deficiency having dental restoration

Epistaxis and airway trauma are often associated with nasotracheal intubation. We describe a patient with Factor IX deficiency who required nasotracheal intubation. An inexpensive, nonproprietary, rapid technique was used to reduce the trauma of intubation.

Lumbar Epidural Blood Patch to Treat a Large, Symptomatic Postsurgical Cerebrospinal Fluid Leak of 5 Weeks Duration in a 3-Year-Old

A 3-yr-old with B-cell lymphoma presented with a 5-wk history of 400 mL/day cerebrospinal fluid (CSF) leak, which precluded chemotherapy, after placement of an Omaya reservoir and drain. Surgical repair was unsuccessful. Symptoms included irritability, failure to eat and noncommunication. After lumbar epidural blood patch with 7 mL the symptoms resolved immediately, allowing recommencement of chemotherapy. Epidural blood patch should be considered as possible early treatment for CSF leaks.

IMPLICATIONS

An epidural blood patch successfully treated a large cerebrospinal fluid leak of long duration in a 3-yr-old. Considering the distress of such a leak to the patient, staff, and parents, epidural blood patch may be considered as an early treatment option.

Paediatric regional anaesthesia, a survey of practice in the United Kingdom

BACKGROUND

A variety of techniques and drugs, many unlicensed, is used in paediatric regional anaesthesia. This study is the first to survey paediatric anaesthetists about the techniques and drugs used in paediatric regional anaesthesia. The aim is to provide a record and benchmark of UK practice.

METHODS

A postal questionnaire was sent to all members of the Association of Paediatric Anaesthetists residing in the UK. Information was requested on the type of hospital worked in, years of practice, paediatric anaesthesia workload, regional anaesthesia techniques used, and drugs used in regional anaesthesia.

RESULTS

A total of 220 responses from 264 questionnaires (83.3%) were received. Of these respondents, 155 (70%) practised paediatric anaesthesia as more than 50% of their workload, and 10 had retired or returned blank forms. Two hundred and two of 210 (96%) use caudal anaesthesia and 151 (72%) use caudal, epidural and peripheral block. One hundred and ninety-two of 210 (91%) have no lower age limit for using caudal anaesthesia. One hundred and twenty-three of 210 anaesthetists (58%) used adjuvants with local anaesthetics in caudal block, the most common being fentanyl [44/210 (21%)], clonidine [55/210 (26%)], diamorphine [27/210 (13%)] and ketamine [67/210 (32%)]. Those working in specialist centres or teaching hospitals or who had a greater paediatric anaesthesia workload were more likely to use a greater variety of regional anaesthesia techniques.

CONCLUSIONS

Caudal anaesthesia is widely used for patients of all ages by almost all practitioners. Most anaesthetists at all hospital types and experience levels use adjuvants with local anaesthetics when performing caudal anaesthesia. Those with more experience in paediatric anaesthesia and those in specialist centres commonly use other neuraxial and peripheral block techniques.

A comparison of Internet usage between two residency programs in the United Kingdom and the United States

STUDY OBJECTIVE

To survey the pattern of use and availability of the Internet among anesthesia residents.

DESIGN

Survey questionnaire.

SETTING

University hospital.

MEASUREMENTS

A postal questionnaire of Internet attitudes and usage was sent to trainees in Anesthesiology in two training programs: the University of New Mexico, Albuquerque, NM (UNM) and the North West Regional Health Authority, Manchester, UK (NWR). A repeat questionnaire was sent to nonresponders after 4 weeks. Telephone interviews were conducted with hospital administration to determine availability and cost of the Internet.

MAIN RESULTS

Response rates were 67% (82/122) from the NWR and 83% (25/31) from UNM. Compared with NWR, residents at UNM used the Internet longer for general (median 3 vs. 2 yrs; p < 0.001) and medical (median 2 vs. 1.2 yrs; p < 0.001) purposes. All (31/31) UNM trainees and 73% (89/122) of NWR trainees had Internet access. More NWR trainees who had Internet access at work (60/61; 98%) used it for medically related purposes than those without work access (17/21, 81%; p < 0.001). More UNM trainees (19/25; 76%) accessed web sites other than those of official national organizations than did NWR trainees (40/82, 49%; p = 0.046). Approximately 75% of all trainees access web sites of the Association of Anesthetists and Royal College of Anesthetists (in the NWR) the American Society of Anesthesiologists (ASA) and American Board of Anesthesiology (in UNM) and online journals. The most popular sites were GASNET (Global Anesthesiology Server Network; NWR) and ASA (American Society of Anesthesiologists; UNM). Both UNM and NWR trainees perceived the Internet as supplying useful and accurate information.

CONCLUSIONS

If the reported survey results are representative of Internet use among anesthesia residents in the United States and UK, Internet access at work is associated with greater Internet use for medical purposes, perhaps in part because residents perceive it to be a convenient and accurate resource.

A Comparison of Internet Usage Between Two Residency Programs in the United Kingdom and the United States

BACKGROUND

The Internet is a potentially useful tool in medical education. The patterns of its usage and availability among anesthesia residents have not been surveyed. This survey, conducted in 2000, attempts to gain insight into and quantify its usage.

METHODS

After ethics committee approval, a postal questionnaire of attitudes and usage was sent to trainees in Anesthesiology in two training programs: the University of New Mexico, USA (UNM) and the North West Regional Health Authority, UK (NWR). A repeat questionnaire was sent to non-responders after four weeks. Telephone interviews were conducted with hospital administration to determine availability and cost of the Internet.

RESULTS

Response rates were 67% (82/122) from the NWR and 83% (25/31) from UNM. Compared to UNM, residents at UNM used the Internet longer for general (median 3 vs. 2 years, p<0.001) and medical (median 2 vs. 1.2 years, p<0.001) purposes. All (31/31) UNM trainees and 73 % (89/122) of NWR trainees had Internet access. More NWR trainees who had Internet access at work (98%; 60/61)) used it for medically related purposes than those work access (17/21, 81%) (p<0.001). More UNM trainees (76%; 19/25) accessed web sites other than those of official national organizations than NWR trainees (40/82, 49%) (p=0.046). Approximately 75% of all trainees access web sites of the Association of Anaesthetists and Royal College of Anaesthetists (in the NWR) the American Society of Anesthesiologists and American Board of Anesthesiology (in UNM) and on-line journals. The most favorite sites were GASNET (NWR) and ASA (UNM). Both UNM and NWR trainees perceived the Internet as supplying useful and accurate information.

CONCLUSIONS

If the reported survey results are representative of Internet use among anesthesia residents in the USA and UK, access at work is associated with greater Internet use for medical purposes perhaps in part because residents perceive it as a convenient and accurate resource.

Acousto-optical deflection-based whole channel scanning for microchip isoelectric focusing with laser-induced fluorescence detection

This paper describes the development of a technique amenable to the separation of proteins on a microchip by isoelectric focusing (IEF) with entire channel scanning laser-induced fluorescence detection using acousto-optical deflection (AOD). The ability to use AOD to scan the portions of or the entire length of an IEF separation channel allows for high-speed analysis since the mobilization step is circumvented with this technique. Employing no moving parts eliminates mechanical noise and, not only is there no loss of resolution, AOD scanning can potentially increase resolution. The ability of AOD to provide ultra-fast scanning rates (kHz timescale) allows for real-time imaging of the focusing process. This is demonstrated with the separation of naturally fluorescent proteins using entire channel (total scanning range of 2.4 cm) AOD-mediated scanning laser-induced fluorescence detection.

Hepatitis C viral clearance and antibody reactivity patterns in persons with haemophilia and other congenital bleeding disorders

We studied hepatitis C virus (HCV) clearance and antibody reactivity patterns in a cohort of 100 haemophiliacs exposed to unsterilized blood products, of whom 25 were antiHCV negative and 75 were antiHCV positive [49 human immunodeficiency virus (HIV) negative and 26 HIV positive]. HCV RNA was measured by the 2.0 bDNA assay and an 'in-house' polymerase chain reaction assay. Antibody reactivity patterns were examined using a recombinant immunoblot assay (RIBA). Prior HCV infection was found in two (8%) of 25 antiHCV negative patients. HCV viraemia persisted in all 26 antiHCV+ patients who were coinfected with HIV. HCV RNA clearance was found in 12 (25%) of 49 antiHCV+, HIV- patients. Viral clearance was associated with younger current age (P < 0.01) and age at infection (P < 0.001), but not with duration of infection or with dose or frequency of clotting factor use. RIBA ratios reflecting an index of each patient's overall reactivity to four HCV epitopes were significantly lower in those with viral clearance (P < 0.0001). Over a period of 15 years, those with viral clearance demonstrated significant loss of reactivity to the NS3, NS4 and NS5 epitopes, while those with viral persistence demonstrated relatively stable reactivities to all epitopes. We conclude that spontaneous HCV RNA clearance in haemophiliacs is age-related and is unlikely to occur in those coinfected with HIV. The loss of antibody reactivity for some epitopes, especially c22 (core), may be a marker for the natural resolution of chronic HCV infection.

A method for UV-bonding in the fabrication of glass electrophoretic microchips

This paper presents an approach for the development of methodologies amenable to simple and inexpensive microchip fabrication, potentially applicable to dissimilar materials bonding and chip integration. The method involves a UV-curable glue that can be used for glass microchip fabrication bonding at room temperature. This involves nothing more than fabrication of glue "guide channels" into the microchip architecture that upon exposure to the appropriate UV light source, bonds the etched plate and cover plate together. The microchip performance was verified by capillary zone electrophoresis (CZE) of small fluorescent molecules with no microchannel surface modification carried out, as well as with a DNA fragment separation following surface modification. The performance of these UV-bonded electrophoretic microchips indicates that this method may provide an alternative to high temperature bonding.

Intra- and interlaboratory variabilities of results obtained with the Quantiplex human immunodeficiency virus type 1 RNA bDNA assay, version 3.0

Normal assay variation associated with bDNA tests for human immunodeficiency virus type 1 (HIV-1) RNA performed at two laboratories with different levels of test experience was investigated. Two 5-ml aliquots of blood in EDTA tubes were collected from each patient for whom the HIV-1 bDNA test was ordered. Blood was stored for no more than 4 h at room temperature prior to plasma separation. Plasma was stored at -70 degrees C until transported to the Central Pennsylvania Alliance Laboratory (CPAL; York, Pa.) and to the Hershey Medical Center (Hershey, Pa.) on dry ice. Samples were stored at < or =-70 degrees C at both laboratories prior to testing. Pools of negative (donor), low-HIV-1-RNA-positive, and high-HIV-1-RNA-positive plasma samples were also repeatedly tested at CPAL to determine both intra- and interrun variation. From 11 August 1999 until 14 September 2000, 448 patient specimens were analyzed in parallel at CPAL and Hershey. From 206 samples with results of > or =1,000 copies/ml at CPAL, 148 (72%) of the results varied by < or =0.20 log(10) when tested at Hershey and none varied by >0.50 log(10). However, of 242 specimens with results of <1,000 copies/ml at CPAL, 11 (5%) of the results varied by >0.50 log(10) when tested at Hershey. Of 38 aliquots of HIV-1 RNA pool negative samples included in 13 CPAL bDNA runs, 37 (97%) gave results of <50 copies/ml and 1 (3%) gave a result of 114 copies/ml. Low-positive HIV-1 RNA pool intrarun variation ranged from 0.06 to 0.26 log(10) while the maximum interrun variation was 0.52 log(10). High-positive HIV-1 RNA pool intrarun variation ranged from 0.04 to 0.32 log(10), while the maximum interrun variation was 0.55 log(10). In our patient population, a change in bDNA HIV-1 RNA results of < or =0.50 log(10) over time most likely represents normal laboratory test variation. However, a change of >0.50 log(10), especially if the results are >1,000 copies/ml, is likely to be significant.

Analysis of a large collection of natural HIV-1 integrase sequences, including those from long-term nonprogressors

A large collection of natural HIV-1 integrase (IN) sequences has not previously been described. We reasoned that analysis of such sequences would address whether natural variation of HIV-1 IN contributes to the pathogenesis of AIDS and might also identify amino acid residues important for IN function. Sequences encoding HIV-1 IN were amplified from cryopreserved lymphocytes or plasma obtained at different times from 10 hemophilia patients who had been observed for up to 17 years. The region of the HIV-1 genome that encodes the 288-amino acid IN protein was sequenced from a total of 102 clones; information was obtained for 99.97% of 29,478 amino acid positions. Phylogenetic analysis indicated that patient samples were unique. Interpatient nucleic acid distances ranged from 0.8% to 4.9%, highlighting the tight conservation of this genomic region. No major differences were found between DNA and RNA or between early and late time points from the same patient. Significantly, no amino acid changes that might account for the variable rate of disease progression between patients were evident. Only one amino acid substitution involved a highly conserved residue known to be important for enzymatic activity. However, several interesting amino acid substitutions were noted, including residues within the C-terminal region of the protein for which sequence comparisons between animal retroviruses have not been very informative. These results should encourage the pursuit of anti-integrase therapies, especially inasmuch as the apparent biologic constraints on the IN sequence may deter the development of drug resistance.

Morphine pharmacokinetics during continuous infusion of morphine sulfate for infants receiving extracorporeal membrane oxygenation

OBJECTIVES

To determine a) if serum morphine concentration changes during the first 3 hrs of extracorporeal membrane oxygenation (ECMO); and b) if absorption of morphine onto the membrane oxygenator is responsible for these changes. Also, morphine clearance during the first 5 days of ECMO was studied.

DESIGN

Prospective, open-label study with consecutive patient enrollment.

SETTING

Neonatal intensive care unit at a university-affiliated, children's hospital.

SUBJECTS

Eleven neonates with severe persistent pulmonary hypertension of the newborn receiving continuous intravenous infusions of morphine sulfate and requiring ECMO.

INTERVENTIONS

Blood samples were obtained from the subjects and ECMO circuits at predetermined time intervals.

MEASUREMENTS AND MAIN RESULTS

Serum morphine concentration was determined using high-performance liquid chromatography. Morphine concentrations were no different from baseline at 5 mins, 1 hr, or 3 hrs after beginning ECMO. There was no significant difference in morphine concentration from samples taken immediately proximal and distal to the membrane oxygenator at 5 mins, 1 hr, and 3 hrs after the start of ECMO. Morphine clearance was calculated on days 1, 3, and 5 of ECMO. The mean value for morphine clearance was 11.7 +/- 9.3 (SD) ml/min/kg (range 2.6 to 34.5).

CONCLUSIONS

The initiation of ECMO does not lead to a significant decrease in serum morphine concentration and there is no uptake of morphine onto the membrane oxygenator of the ECMO circuit. Morphine clearance for infants receiving ECMO is variable.

Suppression of hepatitis C virus (HCV) replication by hepatitis D virus (HDV) in HIV-infected hemophiliacs with chronic hepatitis B and C

Most hemophiliacs who are coinfected with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) have high serum levels of HCV RNA. To study the impact of multiple hepatitis virus infections, we evaluated all eight chronic carriers of hepatitis B surface antigen (HBsAg) from a previously studied cohort of 99 hemophiliacs with chronic HIV and HCV infections. Stored serum or plasma samples were tested for antibody to hepatitis D virus (anti-HDV) by ELISA; qualitatively for HCV RNA, HBV DNA, and HDV RNA by the polymerase chain reaction (PCR); and quantitively for HIV RNA, HCV RNA, and hepatitis B virus (HBV) DNA by a quantitative branched DNA signal amplification assay. HCV RNA was detected in only one of five patients with HDV infections on a cross-sectional study, and this individual had low levels (< 3.5 x 10(5) genome eq/ml) of HCV RNA. In contrast, all three without HDV infections had high levels (> 1.5 x 10(7) genome eq/ml) of HCV RNA. HIV RNA was present in all eight patients. There was no correlation between the level of HIV RNA and the presence of hepatitis viruses. Three of the eight patients (38%) died of liver failure and another has hypersplenism with hypoprothrombinemia. We conclude that HDV infection appears to suppress HCV replication and that liver failure is common in adult HIV-infected hemophiliacs with chronic HCV and HBV infections. These findings have implications for the therapy of HCV-infected hemophiliacs who are HBsAg positive.

Secondary structure of M13 coat protein in phospholipids studied by circular dichroism, Raman, and Fourier transform infrared spectroscopy

There is considerable uncertainty about the precise secondary structure adopted by the M13 coat protein when embedded in a phospholipid bilayer. Circular dichroism (CD) spectroscopy suggests that a major change in the structure of the coat protein occurs upon membrane insertion. It is reported that the structure of the protein in the membrane has only about 50% alpha-helix, the rest being mainly in a beta-sheet conformation, whereas the protein is almost completely alpha-helical when intact in the phage. In this study we have undertaken a spectroscopic analysis using Fourier transform infrared, Raman, and CD spectroscopy to characterize the secondary structure of M13 coat protein when present in membranes consisting of dioleoylphosphatidylglycerol and dimyristoylphosphatidylglycerol. In sharp contrast to earlier CD studies, our results indicate that the coat protein in its membrane-embedded state has a very high alpha-helical content with virtually no beta-sheet structures present. This result indicates that the structures of the coat protein when intact in the phage or when embedded in the membrane are similar. Although our results differ from earlier CD studies, they are consistent with a recent NMR study, which showed that the M13 coat protein in sodium dodecyl sulfate micelles is primarily alpha-helical with no evidence for beta-sheet structure [Henry, G. D., & Sykes, B.D. (1992) Biochemistry 31, 5284-5297]. These results lead to the conclusion that the M13 coat protein can insert from the membrane-bound state into a virus particle with a similar secondary structure, without large energy implications.(ABSTRACT TRUNCATED AT 250 WORDS)

The macroscopic organization of reconstituted M13 coat protein-phospholipid systems. An EPR spectroscopy and polarizing microscope study

The coat protein of the bacteriophage M13 in the alpha-helical state is reconstituted in macroscopically oriented systems of dioleoylphosphatidylcholine that are prepared by squeezing the reconstituted material between glass plates. The coat protein dramatically influences the macroscopic orientation of the multibilayers, as is investigated by polarizing microscopy and EPR spectroscopy of the cholestane spin label embedded in the bilayers. It is found that with increasing amounts of protein the spontaneous macroscopic orientation of the reconstituted system decreases. This effect is proposed to be due to an increase of the apparent viscosity of the lipid-protein systems with increasing amounts of protein. This is assumed to arise from a sticky effect of the C- and N-terminal protein parts that extend into the aqueous phase between the bilayers.

A small protein in model membranes: a time-resolved fluorescence and ESR study on the interaction of M13 coat protein with lipid bilayers

Model membranes with unsaturated lipid chains containing various amounts of M13 coat protein in the alpha-helical form were studied using time-resolved fluorescence and ESR spectroscopy. The lipid-to-protein (L/P) ratios used were > 12 to avoid protein-protein contacts and irreversible aggregation leading to beta-polymeric coat protein. In the ESR spectra of the 12-SASL probe in dioleoyl phosphatidylcholine (DOPC) bilayers no second protein induced component is observed upon incorporation of M13 coat protein. However, strong effects are detected on the ESR lineshapes upon changing the protein concentration. The ESR lineshapes are simulated by assuming a fixed ratio between the parallel (D parallel) and perpendicular (D perpendicular) diffusion coefficients of 4, and an order parameter equal to zero. It is found that increasing the protein concentration from L/P infinity to L/P 15 results in a decrease of the rotational diffusion coefficient D perpendicular from 3.4 x 10(7) to 1.9 x 10(7) s-1. In the time-resolved fluorescence experiments with DPH-propionic acid as a probe, it is observed that increasing the M13 coat protein concentration causes an increase of the two fluorescent lifetimes, indicating an increase in bilayer order. Analysis of the time-resolved fluorescence anisotropy decay allows one to quantitatively determine the order parameters <P2> and <P4>, and the rotational diffusion coefficient D perpendicular of the fluorescent probe. The order parameters <P2> and <P4> increase from 0.34 to 0.55 and from 0.59 to 0.77, respectively, upon adding M13 coat protein to DOPC bilayers with an L/P ratio of 35.(ABSTRACT TRUNCATED AT 250 WORDS)

Formation of non-bilayer structures induced by M13 coat protein depends on the conformation of the protein

A comparison is made of the interaction of the coat protein of bacteriophage M13 in a predominant alpha-helix conformation and in a predominant beta-sheet conformation. To perform a systematic study of the interaction between the protein in these two different forms of the surrounding lipid matrix, NMR spectra of 2H-nuclei of specific labelled phospholipid systems are measured. In addition 31P-NMR is employed to provide information about the morphological structure adopted by the reconstituted lipid/protein systems. From the 2H-NMR studies on specific headgroup and chain deuterium labelled phospholipids it is found that the protein in the predominant beta-sheet conformation causes a fraction of lipids to be trapped. By combining the results from the headgroup and acyl chains of the phospholipids, it is concluded that the trapped lipids are arranged in a non-bilayer structure, probably caused by a misfitting of the hydrophobic core of the protein and the membrane bilayer. The protein in the predominant alpha-helix conformation perfectly fits in the lipid bilayer and has only minor influences on the surrounding lipid matrix. A new model is proposed to explain the presence of the trapped lipids in the lipid/protein systems.

Stoichiometry, selectivity, and exchange dynamics of lipid-protein interaction with bacteriophage M13 coat protein studied by spin label electron spin resonance. Effects of protein secondary structure

Bacteriophage M13 major coat protein has been isolated with cholate and reconstituted in dimyristoyl- and dioleoylphosphatidylcholine (DMPC and DOPC, respectively) bilayers by dialysis. Fourier transform infrared spectra of DMPC/coat protein recombinants confirmed that, whereas the protein isolated by phenol extraction was predominantly in a beta-sheet conformation, the cholate-isolated coat protein contained a higher proportion of the alpha-helical conformation [cf. Spruijt, R. B., Wolfs, C. J. A. M., & Hemminga, M. A. (1989) Biochemistry 28, 9158-9165]. The cholate-isolated coat protein/lipid recombinants gave different electron spin resonance (ESR) spectral line shapes of incorporated lipid spin labels, as compared with those from recombinants with the phenol-extracted protein that were studied previously [Wolfs, C. J. A. M., Horváth, L. I., Marsh, D., Watts, A., & Hemminga, M. A. (1989) Biochemistry 28, 9995-10001]. Plots of the ratio of the fluid/motionally restricted components in the ESR spectra of spin-labeled phosphatidylglycerol were linear with respect to the lipid/protein ratio in the recombinants up to 20 mol/mol. The corresponding values of the relative association constants, Kr, and number of association sites, N1, on the protein were Kr approximately 1 and N1 approximately 4 for DMPC recombinants and Kr approximately 1 and N1 approximately 5 for DOPC recombinants. Simulation of the two-component lipid spin label ESR spectra with the exchange-coupled Bloch equations gave values for the off-rate of the lipids leaving the protein surface of 2.0 x 10(7) s-1 at 27 degrees C in DMPC recombinants and 3.0 x 10(7) s-1 at 24 degrees C in DOPC recombinants.(ABSTRACT TRUNCATED AT 250 WORDS)

Conformation and aggregation of M13 coat protein studied by molecular dynamics

Molecular dynamics (MD) simulations are performed on M13 coat protein, a small membrane protein for which both alpha- and beta-structures have been suggested. The simulations are started from initial conformations that are either monomers or dimers of alpha-helices or U-shaped beta-sheets. The lipid bilayer is represented by a hydrophobic potential. The results are analyzed in terms of stability, energy and secondary structure. The U-shaped beta-structure changes from a planar to a twisted form with larger twist for the monomer than the dimer. The beta-sheet is much more flexible than the alpha-helix as monitored by the root mean square (rms) fluctuations of the C alpha atoms. A comparison of the energies after 100 ps MD simulation shows that of the monomers, the alpha-helix has the lowest energy. The energy difference between alpha- and beta-structures decreases from 266 kJ/mol to 148 kJ/mol, when going from monomers to dimers. It is expected that this difference will decrease with higher aggregation numbers.

A NMR investigation on the interactions of the alpha-oligomeric form of the M13 coat protein with lipids, which mimic the Escherichia coli inner membrane

The interaction of the M13 bacteriophage major coat protein in the alpha-oligomeric form with specifically deuterated phospholipid headgroups which mimic the Escherichia coli inner membrane, has been studied using NMR methods. As can be seen from the deuterium NMR spectra obtained with headgroup trimethyl deuterated DOPC, the coat protein in the alpha-oligomeric form does not give rise to trapped lipids as observed with M13 coat protein in the beta-polymeric form (Van Gorkom et al. (1990) Biochemistry 29, 3828-3834). The quadrupolar splittings of the alpha headgroup methylene deuterons of deuterated phosphatidylcholine and phosphatidylethanolamine decrease, whereas the quadrupolar splittings of the beta headgroup methylene deuterons of the two lipids increase with increasing protein content. All deuterated segments in the phosphatidylglycerol headgroup show the same relative decrease of the NMR quadrupolar splittings. These results are interpreted in terms of a change in torsion angles of the methylene groups, induced by positive charges, probably lysine residues of the protein at the membrane surface. For all lipid bilayer compositions studied the head-group perturbations are similar. It is concluded that there is no strong specific interaction between one of the lipid types examined and the M13 coat protein. From the spin-spin (T2e) relaxation time and spin-lattice (T1z) relaxation time of all deuterated lipids it is concluded that at the bilayer surface only slow motions are affected by the M13 coat protein.

Analysis of time-resolved fluorescence anisotropy in lipid-protein systems. I. Application to the lipid probe octadecyl rhodamine B in interaction with bacteriophage M13 coat protein incorporated in phospholipid bilayers

Fluorescent probes located in heterogeneous environments give rise to anomalous time-resolved fluorescence anisotropy. A simple analytical expression of anisotropy has been derived for the case of a small difference in local fluorescence lifetimes. The expression has the diagnostic advantage that the time dependence of the fluorescence anisotropy can be predicted from the differences in fluorescence lifetimes and residual anisotropies of the probes located in different sites. Using this model, the local fluorescence anisotropy parameters and the relative contributions of the lipid probe octadecyl rhodamine B in a lipid environment and in the vicinity of bacteriophage M13 coat protein reconstituted in phospholipid bilayers, composed of 80% 1,2-dimyristoyl-sn-glycero-3-phosphocholine and 20% 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol have been determined experimentally. At 40 degrees C, the correlation times for bound and free probes are 2.3 and 3.0 ns, respectively, while the corresponding order parameters are 0.85 and 0.62, respectively.

Acquired dysfibrinogenemia in a hemophiliac with hepatoma: resolution of fibrinogen dysfunction following chemotherapy

A 17-year-old male with previously undiagnosed congenital Factor IX deficiency (13%) presented with gastrointestinal bleeding and a hepatic mass. Prolonged thrombin and Reptilase times, which partially corrected with CaCl2 and a discrepancy between thrombin-clottable and immunoreactive plasma fibrinogen, suggested a dysfibrinogenemia. Laparotomy disclosed metastatic hepatoma. Adequate hemostasis was obtained with clotting factor replacement, but wound healing was delayed. Patient fibrinogen purified with 2.1 M glycine migrated normally on immunoelectrophoresis and 7.5% polyacrylamide-SDS gel electrophoresis. However, fibrin monomers prepared from purified patient fibrinogen displayed impaired aggregation at high and low ionic strengths when compared with fibrin monomers from normal and control Factor IX deficient subjects. Aggregation of normal monomers was delayed when mixed 1:1 with patient monomers. Fibrinopeptide release was normal, and total sialic acid content was similar to that of normal and control fibrinogens. Chemotherapy, consisting of 5-FU given via intra-arterial hepatic infusion, was accompanied by significant transient clinical improvement which coincided with correction of thrombin clotting times and fibrin monomer aggregation. Reappearance of fibrinogen dysfunction occurred with clinical deterioration prior to death from metastatic hepatoma and sepsis. This case is the first to corroborate the postulated tumor marker role of dysfibrinogenemia in a patient with hepatoma by documenting a direct relationship with response to chemotherapy.

Altered serum factor VIII-related antigen (VIII : AGN)/von Willebrand factor (VIII : vWf) in haemophiliacs with inhibitors to factor VIII procoagulant activity (VIII : C)

Inhibitors to factor VIII (anti-F VIII) developing in patients with classic haemophilia have apparent specificity for the factor VIII procoagulant activity (VIII : C), rather than the factor VIII-related antigen (VIII : AGN) and von Willebrand factor (VIII : vWf) regions of the factor VIII complex. Since procoagulant function is absent following in vitro clotting, but serum retains VIII : AGN/vWf properties, we searched for differences in VIII : AGN and VIII : vWf of inhibitor serum that might relate to the presence of anti-F VIII. Rocket immunoelectrophoresis and the washed platelet ristocetin assay were performed on the plasma and serum of nine haemophiliacs with inhibitors, 23 non-inhibitor haemophiliacs and six normal subjects. Unlike normal and non-inhibitor haemophilic sera, that from five of nine inhibitor patients demonstrated absent VIII : vWf and significantly lower VIII : AGN (p less than 0.05). Furthermore, VIII : AGN of faster mobility was detected on crossed immunoelectrophoresis of the sera of three inhibitor patients. Thrombin clotting of plasma from haemophiliacs with high titer anti-F VIII was associated with a greater loss of VIII : vWf than seen with non-inhibitor haemophilic plasma. This effect was independent of the presence of platelets. These data indicate that in vitro clotting is associated with alteration in the serum VIII : AGN/vWf of some haemophiliacs with anti-F VIII.