Biochemical and molecular analysis of carboxylesterase-mediated hydrolysis of cocaine and heroin

BACKGROUND AND PURPOSE

Carboxylesterases (CEs) metabolize a wide range of xenobiotic substrates including heroin, cocaine, meperidine and the anticancer agent CPT-11. In this study, we have purified to homogeneity human liver and intestinal CEs and compared their ability with hydrolyse heroin, cocaine and CPT-11.

EXPERIMENTAL APPROACH

The hydrolysis of heroin and cocaine by recombinant human CEs was evaluated and the kinetic parameters determined. In addition, microsomal samples prepared from these tissues were subjected to chromatographic separation, and substrate hydrolysis and amounts of different CEs were determined.

KEY RESULTS

In contrast to previous reports, cocaine was not hydrolysed by the human liver CE, hCE1 (CES1), either as highly active recombinant protein or as CEs isolated from human liver or intestinal extracts. These results correlated well with computer-assisted molecular modelling studies that suggested that hydrolysis of cocaine by hCE1 (CES1), would be unlikely to occur. However, cocaine, heroin and CPT-11 were all substrates for the intestinal CE, hiCE (CES2), as determined using both the recombinant protein and the tissue fractions. Again, these data were in agreement with the modelling results.

CONCLUSIONS AND IMPLICATIONS

These results indicate that the human liver CE is unlikely to play a role in the metabolism of cocaine and that hydrolysis of this substrate by this class of enzymes is via the human intestinal protein hiCE (CES2). In addition, because no enzyme inhibition is observed at high cocaine concentrations, potentially this route of hydrolysis is important in individuals who overdose on this agent.

An improved human carboxylesterase for enzyme/prodrug therapy with CPT-11

CPT-11 is a potent antitumor agent that is activated by carboxylesterases (CE) and intracellular expression of CEs that can activate the drug results in increased cytotoxicity to the drug. As activation of CPT-11 (irinotecan-7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin) by human CEs is relatively inefficient, we have developed enzyme/prodrug therapy approaches based on the CE/CPT-11 combination using a rabbit liver CE (rCE). However, the in vivo application of this technology may be hampered by the development of an immune response to rCE. Therefore, we have developed a mutant human CE (hCE1m6), based on the human liver CE hCE1, that can activate CPT-11 approximately 70-fold more efficiently than the wild-type protein and can be expressed at high levels in mammalian cells. Indeed, adenoviral-mediated delivery of hCE1m6 with human tumor cells resulted in up to a 670-fold reduction in the IC(50) value for CPT-11, as compared to cells transduced with vector control virus. Furthermore, xenograft studies with human tumors expressing hCE1m6 confirm the ability of this enzyme to activate CPT-11 in vivo and induce antitumor activity. We propose that this enzyme should likely be less immunogenic than rCE and would be suitable for the in vivo application of CE/CPT-11 enzyme/prodrug therapy.

Intervention to reduce environmental tobacco smoke exposure in Latino children: null effects on hair biomarkers and parent reports

OBJECTIVE

To evaluate the effectiveness of a lay delivered intervention to reduce Latino children's exposure to environmental tobacco smoke (ETS). The a priori hypothesis was that children living in households that were in the intervention group would have lower exposure over time than measurement only controls.

DESIGN

A two group, randomised control trial was conducted.

SETTING

Areas of San Diego county with a large Latino population.

PARTICIPANTS

143 Latino parent-child pairs.

INTERVENTION

Trained bicultural and bilingual Latina lay community health advisors, or promotoras, conducted problem solving aimed at lowering the target child's exposure to ETS in the household. Six home and telephone sessions were delivered by the promotoras over a four month period.

MAIN OUTCOME MEASURES

Outcome measures were collected at baseline, immediately post-intervention, three months post-intervention, and 12 months post-intervention. Four outcomes were considered: (1) parent's paper-and-pencil reports of the child's past month exposure; (2) hair samples from the child analysed for past month nicotine; (3) hair samples from the child analysed for past month cotinine; and (4) per cent confirmed reducers.

RESULTS

There were no significant condition-by-time interactions, the term indicative of a differential intervention effect. Significant or near significant time main effects were seen for children's hair cotinine, per cent confirmed reducers, and, in particular, parent reports of exposure.

CONCLUSIONS

Applying a lay promotora model to deliver the behavioural problem solving intervention unfortunately was not effective. A likely explanation relates to the difficulty of delivering a relatively complex intervention by lay women untrained in behaviour change theory and research methods.

Contrast?Enhanced Cardiac Magnetic Resonance in a Patient with Familial Isolated Ventricular Non?compaction

Isolated ventricular non-compaction (IVNC) is an idiopathic form of cardiomyopathy. Recent clinical reports have suggested that this form of cardiomyopathy is more frequently associated with complications of congestive heart failure, thromboembolism and malignant ventricular arrhythmias. Contrast enhanced cardiac magnetic resonance imaging with its excellent spatial resolution, its large field of view and its ability to demonstrate thrombus and myocardial scar is an excellent modality to non-invasively assess patients with this form of cardiomyopathy. This paper presents a case of familial isolated ventricular non-compaction. We describe the echocardiographic, X-ray angiographic and cardiac MRI findings. Cine imaging using a steady-state free precession sequence (BFFE) was performed in axial and short axis planes. Left ventricular (LV) mass was estimated both with and without the incorporation of trabeculations from a contiguous stack of short axis images. Trabecular mass was expressed as a percentage of total left ventricular mass. We compared trabecular mass: total LV mass in 10 patients with dilated cardiomyopathy. The mean percentage trabecular mass: LV mass in dilated cardiomyopathy was 11.3% (range 1.5%-19%), and this differed significantly from the trabecular mass of the noncompaction patient (two-tailed Mann-Whitney test, p = 0.028). Trabecular mass of greater than 20% of total myocardial mass may be a useful index to suggest the diagnosis of IVNC. Gadolinium was administered (0.1 mmol/kg). Qualitative analysis of first pass perfusion suggested reduced trabecular perfusion. Early imaging with an inversion recovery sequence and a fixed long inversion time did not demonstrate LV thrombus. Late imaging with the same sequence (TI = 280-300 msec) did not demonstrate myocardial fibrosis.

Causes of elevated troponin I with a normal coronary angiogram

BACKGROUND

The new definition of myocardial infarction (MI) emphasizes the pre-eminent role of troponin for diagnosis. Troponin rise indicates myocardial injury, but is not synonymous with infarction or ischaemia.

AIMS

To review the precipitating event for troponin elevation in patients with angiographically normal coronary arteries, in a district general hospital.

METHODS

Consecutive patients with elevated troponin I (TnI) who underwent angiography for suspected coronary disease were included in the present study if they had normal or mild disease (<50% diameter loss without complex features or thrombus). Precipitating event for TnI elevation was assigned on the totality of clinical evidence.

RESULTS

Twenty-one patients qualified, with an average age of 50 years (range 33-73). Sixty-two per cent of participants were female. Troponin release was attributed to tachycardia in six patients, only two of whom had haemodynamic compromise. Physical exertion was the precipitating factor in two patients; pericarditis in two patients; and severe congestive heart failure in one patient. Ten of 21 patients had no identifiable cause for a rise in TnI concentration. Five of 21 patients had left-ventricular wall motion abnormalities. There were no deaths or MI at 41 +/- 24 weeks follow up.

CONCLUSION

Troponin is a sensitive marker of myocardial injury and may rise following apparently minor insults. A rise in TnI concentration may have a cause other than acute coronary syndrome and may occur without significant angiographic coronary artery disease.

Intra-articular distal radius fractures: arthroscopic assessment of radiographically assisted reduction

The optimal means of assessing articular displacement during closed reduction of distal radius fractures is unknown. The purpose of this study was to evaluate the in vivo accuracy of fluoroscopy (C-arm) and plain radiographs (XR) in measuring articular step-off and gap and to determine if postreduction arthroscopy can identify malreduced intra-articular fractures that would benefit from reduction. Fifteen intra-articular distal radius fractures underwent closed manipulation and percutaneous pinning. Reduction was assessed sequentially by C-arm, XR, and wrist arthroscopy. The width of gapping between articular surface fragments was underestimated to a statistically significant degree by both C-arm and XR. The magnitude of articular step-off measured with arthroscopy was not statistically different than that measured radiographically. In 5 (33%) cases, the optimal reduction obtained using C-arm and XR was found to have an articular displacement of >1mm by adjunctive arthroscopy. Complete reduction and pinning was performed with satisfactory results. These results suggest that adjunctive arthroscopy may detect residual gapping of the articular surface that is not seen by C-arm or XR. Residual displacement noted by adjunctive arthroscopy may prompt another reduction effort and result in an improved articular alignment of intra-articular distal radius fractures.

Pilot test of an Internet virtual world chat room for rural teen smokers

This pilot study evaluated the acceptability and efficacy of an Internet-based virtual reality "world" for teen smoking cessation. Rural teens at six school sites interacted in real-time in the virtual world with a trained cessation counselor and other teen smokers over a 2-month period in seven 1-hour chat sessions. The cessation counselor used motivational interviewing, a "client-centered" nonconfrontational approach to behavior change that has shown promise with behaviors resistant to change. Smoking behavior and attitudes were assessed at baseline, after intervention, and at 1-month follow-up. Significant changes were found in quitting, amount smoked, and intentions to quit. Positive trends were seen in past-week abstinence rates, quit attempts, and attitudes toward quitting.

Correlates of vaccination for hepatitis B among adolescents: results from a parent survey

OBJECTIVE

To identify correlates of hepatitis B vaccination status in sixth-grade students in the year prior to implementation of a requirement mandating immunization for seventh-grade entry.

METHODS

A survey of parents of sixth-graders in 5 schools in San Diego County. Two logistic regression models were tested to predict the outcome variables: initiation and completion of the vaccination series.

RESULTS

Factors associated with initiating the series included a recent nonacute medical visit, white race, hearing about the vaccination law from a health care provider, and the availability of a school-based vaccination clinic. Factors associated with completing the series included English as the primary language spoken at home, hearing about the law from a health care provider, a school-based vaccination clinic, and higher socioeconomic status. Health insurance was not significantly related to either outcome.

CONCLUSIONS

There was a clear benefit for hepatitis B immunization status to have had a recent nonacute medical visit, to have heard about the law from a health care provider, and to have a school-based vaccination clinic. The factors associated with starting vs completing the vaccination series were not identical. However, both health care provider and school characteristics were related to starting and completing the vaccination series. Thus, a multifaceted strategy may be most appropriate for successful coverage of an adolescent population with a vaccination series such as hepatitis B.

Cervical pedicle screws: comparative accuracy of two insertion techniques

STUDY DESIGN

Independently assessed radiographic and anatomic comparison of device implantation methods.

OBJECTIVES

To compare the relative accuracy of two techniques of inserting cervical pedicle screws.

SUMMARY OF BACKGROUND DATA

In an attempt to define the anatomic risks of cervical pedicle screw insertion, image-guided stereotactic technology was shown to be superior to some other methods in vitro.- Meanwhile, in vivo experience with Abumi's technique of screw insertion has had few clinically relevant instances of screw malposition. There has been no direct comparison between current image-guided technology and Abumi's fluoroscopically assisted technique.

METHODS

The pedicles (C3-C7) of human cadaveric cervical spines were instrumented with 3.5-mm screws with either of two techniques. Cortical integrity and potential neurovascular injury were independently assessed by computed tomographic (CT) scans and anatomic dissection. A cortical breach was considered "critical" if the screw encroached on any vital structure. If any part of the screw violated the cortex of the pedicle but no vital structure was at risk for injury, the breach was classified as "noncritical."

RESULTS

In Group I (StealthStation; Sofamor-Danek, Memphis, TN), 82% of screws were placed in the pedicle, and 18% had a critical breach. In Group II (Abumi technique), 88% of screws were placed in the pedicle, and 12% had a critical breach. No statistically significant differences were demonstrated between each group (P = 0.59). Regarding pedicle dimensions and safety of insertion, a critical pedicle diameter of 4.5 mm was determined to be the size below which a critical breach was likely, but above which there was a significantly greater likelihood for safe screw placement. The most common structure injured in each group was the vertebral artery.

CONCLUSIONS

The use of a computer-assisted image guidance system did not enhance safety or accuracy in placing pedicle screws compared with Abumi's technique. Both techniques have a noteworthy risk of injuring a critical structure if inserted into the pedicles with a diameter of less than 4.5 mm. Under laboratory conditions, pedicles with a diameter of more than 4.5 mm have a significantly greater likelihood of being safely instrumented by either technique. These data indicate that cervical pedicle screw placement is feasible, but it should be reserved for selected circumstances with clear indications and in the presence of suitable pedicle morphology.

T-Saw laminoplasty for the management of cervical spondylotic myelopathy: clinical and radiographic outcome

STUDY DESIGN

Independent evaluation of 18 patients with multilevel cervical spondylotic myelopathy who underwent threadwire T-saw laminoplasty.

OBJECTIVES

Assess the efficacy of midline T-saw laminoplasty in non-Japanese patients based on clinical and radiographic criteria.

SUMMARY OF BACKGROUND DATA

Spinous process-splitting laminoplasty has been well accepted in Japan. The results in non-Japanese patients are unknown.

METHODS

A single physician performed independent clinical and radiographic evaluations at latest follow-up (mean, 24 months). In addition to a patient self-assessment questionnaire, objective measures included physical examination, Pavlov's ratio, sagittal canal diameter (by computed tomography), cord compression index, cervical lordosis, range of motion, and complications.

RESULTS

Progression of myelopathy was arrested in all patients. Patients reported improvement in strength (78%), dexterity (67%), numbness (83%), pain (83%), and gait (67%). Bowel and bladder compromise resolved in five of six patients. The mean Nurick score improved from 2.7 to 0.9 (P < 0.001), and the mean Robinson pain score improved from 2.0 to 0.89 (P = 0.002). No patient required narcotic analgesics at latest follow-up compared with eight before laminoplasty. Objectively, 68% of patients with motor weakness regained normal strength (P = 0.001), whereas 50% regained normal sensation (P = 0.003). Radiographic canal expansion was verified by a statistically significant increase in the mean Pavlov ratio and osseous sagittal computed tomographic measurements. The mean cord compression index improved from 0.49 to 0.61 (P = 0.01). There was no significant change in mean cervical lordosis. Graft dislodgment or segmental instability did not occur. Complications included: infection (n = 1) and persistent postoperative motor root lesion at C5 (n = 1).

CONCLUSIONS

T-saw laminoplasty appears to be a safe and effective method of arresting the progression of myelopathy and allowing marked functional improvement in most patients with multilevel cervical spondylotic myelopathy. [Key Words: cervical spine, decompression, laminoplasty, myelopathy, spondylosis]

Laparoscopic hernia repair: the learning curve

The performance of a laparoscopic inguinal hernia repair requires unique technical and cognitive skills which, until recently, were not routinely taught to general surgeons. The initial experience of three surgeons with laparoscopic hernia repair was audited prospectively to assess the learning curve for the technique. From March 1992 to June 1994, transabdominal preperitoneal (TAP) mesh repair was attempted on 172 consecutive inguinal hernias. Three procedures were converted to traditional repairs. The three independent surgeons that performed the repairs had minimal or no prior clinical experience with the technique in the role as primary surgeon. The hernia repairs were divided into two groups. Group 1 consisted of the first 90 hernia repairs in the series, 30 repairs per surgeon. This group was compared to the subsequent 82 repairs (group 2), approximately 27 repairs per surgeon. Patients were followed up for a median of 31 months. Group 1 had more patients who were hospitalized overnight (37% versus 31%), a greater rate of conversion (2.2% versus 1.2%), a higher complication rate (11.7% versus 0%), a higher recurrence rate (12.2% versus 0%), and a longer delay in the return to full activity (11 weeks versus 8 weeks). Also, overall patient satisfaction with their hernia repair was slightly greater in group 2 (score, 9.0/10 versus 8.2/10). The lack of prior experience with the TAP technique (one surgeon) was associated with a marked increase in the number of conversions (two of three total conversions), complications (four of eight total), and hernia recurrences (8 of 11 total). This study demonstrates that a surgeon's initial experience with laparoscopic herniorrhaphy is associated with an identifiable learning curve. Significant improvements in complication and recurrence rates and overall patient satisfaction can be expected after the initial learning phase. Also, a complete lack of prior experience with laparoscopic herniorrhaphy is associated with a higher rate of conversion and significant increases in complications and hernia recurrences.

Increasing response rates to a smoking survey for U.S. Navy enlisted women

This study examined the effectiveness of several persistent strategies to increase the response to a smoking survey among newly enlisted U.S. Navy women. The stepped approach, which included the use of incentives, repeated mailings, alternative survey administration modes, and reminders, was evaluated in terms of effects on response rates and response bias. Demographic and baseline smoking-related characteristics were compared for those responding on time to the initial mailed follow-up survey, reluctant respondents who did not respond initially but eventually completed a survey after further prompting, and non-respondents. Results showed that incentives and persistent efforts were effective in substantially increasing the response among 2,231 eligible participants, more than doubling the response rate (from 24.9% to 52.7%). The characteristics of on-time, reluctant, and non-respondents did not differ significantly in terms of sociodemographic characteristics. On the other hand, on-time respondents were different from both reluctant respondents and non-respondents in terms of smoking-related behaviors.

Effect of an eight week smoking ban on women at US navy recruit training command

OBJECTIVE

To examine the effect of a unique organisational smoking ban on female United States Navy recruits, a population with historically high smoking rates.

SETTING AND DESIGN

Study participants were female recruits (n = 5503) entering the Navy recruit training command between March 1996 and March 1997 (12 consecutive months). Participants completed smoking surveys at entry to recruit training (baseline) and again at graduation from training after exposure to an eight week, 24 hour a day smoking ban. Effects of the ban on baseline to graduation changes in perceptions of being a smoker were examined, and relapse rates among baseline ever smokers was assessed three months after leaving recruit training.

RESULTS

Among all recruits, 41.4% reported being smokers at entry (that is, reported any smoking in the 30 days before entering recruit training). As a result of the ban, there was a significant reduction (from about 41% to 25%, p < 0.001) in the percentage of all women recruits who reported themselves as smokers, a much larger change than expected had no ban been in place. Relapse at the three month follow up varied according to the type of smoker at entry into the Navy, with rates ranging from 89% relapse among baseline daily smokers to 31% among baseline experimenters.

CONCLUSIONS

Findings suggest that the ban provides some smokers who desire to quit with an external impetus and support to do so. However, high relapse rates indicate that more than an organisationally mandated smoking ban during recruit training is needed to help younger smokers, more regular smokers, and those who intend to continue smoking to quit after joining the Navy.

Enhancing response rates to a smoking survey for enlisted U.S. Navy women

This study examined the effectiveness of a stepped approach for increasing response rates to a mailed follow-up smoking survey among newly enlisted women in the navy. The effect of the stepped approach on response rates and on the characteristics of respondents was evaluated. Also, costs were estimated for each of the steps to determine their relative benefits. Results showed that the stepped approach was effective in more than doubling the survey response rate among smokers. Reluctant respondents did not differ from on-time respondents in terms of demographics or baseline smoking, although nonrespondents were less educated and heavier smokers than on-time and reluctant respondents. Strategies documented here could well apply to survey efforts with other hard-to-reach populations.

Does the US Navy attract young women who smoke?

OBJECTIVE

To assess whether the United States Navy is disproportionately attracting and recruiting female smokers from the civilian sector.

METHODS

Standardised comparisons of cigarette use among Navy women recruits and civilian women were conducted with data from a 1996-97 Department of Defense study and the 1994 National Health Interview Survey.

RESULTS

Young Navy women recruits (18-22 years) had significantly higher rates of current and heavy smoking than their civilian counterparts after adjusting for differences in sociodemographic characteristics. Smoking rates among older recruits and civilian women (23-30 years) were not significantly different.

CONCLUSIONS

It seems that the Navy attracts young civilian women who already smoke, many of whom smoke heavily.

Independent evaluation of the California Tobacco Education Program

OBJECTIVE

To monitor the implementation of tobacco control programs and research in accordance with California's Proposition 99, approved by the voters in 1988, which increased the state's cigarette tax by 25 cents and designated one quarter of the increased revenue-approximately $100 million per year-to develop statewide media campaigns and to fund local health departments, community-based organizations, schools, and agencies working with high risk populations.

METHODS

The authors evaluated the extent and the effectiveness of the implementation independently with standardized forms developed to track any tobacco-related information and activities, local media campaigns, changes in local policies and ordinances, training sessions, and prevention and cessation programs. Activities were reported on the forms to the authors monthly or quarterly.

RESULTS

The evaluation indicated that local health departments, community-based organizations, and other group produced an exceedingly high volume of diverse tobacco control activities throughout the state. They reached a variety of ethnic groups and high risk populations with their programs. The data also show that local health departments and competitive grantees responded with an overall shift in their approach to tobacco control and moved from interventions focused primarily on individual people to broader, more community- and environment-oriented interventions. Additionally, analysis of the wholesale tobacco tax revenues revealed that per capita purchasing continued to decline in California at a rate greater than in the rest of the United States.

CONCLUSION

The evaluation demonstrated that Proposition 99 accomplished much of what it set out to do-reducing tobacco prevalence, reaching out to underserved populations, and heightening the awareness of the dangers of environmental tobacco smoke.

Retroviral transfer of a bacterial alkyltransferase gene into murine bone marrow protects against chloroethylnitrosourea cytotoxicity

The chloroethylnitrosoureas (CENUs) are important antineoplastic drugs for which clinical utility has been restricted by the development of severe delayed myelosuppression in most patients. To investigate the potential of DNA repair proteins to reduce bone marrow sensitivity to the CENUs, we transferred the Escherichia coli ada gene, which encodes a Mr 39,000 O6-alkylguanine-DNA alkyltransferase (ATase), into murine bone marrow cells by the use of a high-titer ecotropic retrovirus. The ada-encoded ATase is resistant to O6-benzylguanine (O6-BG), a potent inhibitor of the mammalian ATases, thus affording the bone marrow an additional level of protection against CENUs. In methylcellulose cultures, ada-infected hematopoietic progenitor cells were twice as resistant as uninfected cells to the toxic effects of 1, 3-bis(2-chloroethyl)-1-nitrosourea (BCNU) following treatment with O6-BG. Although showing no obvious protective effects against leukopenia, overexpression of the bacterial ATase activity reduced the severity of anemia and thrombocytopenia in mice treated with O6-BG and BCNU. These effects, which were maximal at a BCNU dose of 12.5 mg/kg, were associated with improved survival when BCNU was given at this dose. At lower BCNU doses cytotoxicity was limited in both transduced and control mice, and at higher doses the protective effect was saturated due to cytotoxicity. These results suggest that ada gene therapy may be a feasible approach to amelioration of delayed myelosuppression following O6-BG plus CENU combination chemotherapy.

Thoracic epidural abscess

Twenty-one cases of thoracic spinal epidural abscess occurring over a 10-year period were retrospectively reviewed. Diagnosis was made by MRI or myelography and confirmed in the operative cases. A bacterial agent was isolated in 18 of the cases (86%). When measured, the erythrocyte sedimentation rate was elevated in all cases. Four patients who presented without neurologic deficits remained intact. All patients who presented with neurological deficits underwent surgical intervention in addition to intravenous antibiotics. Of the 15 patients who presented with a paraparesis of less than antigravity strength, five eventually were independent ambulators and continent. A good outcome resulted in 80% of those who underwent decompression within 24 h, as opposed to only 10% of the patients decompressed after 24 h. Good results can be obtained despite severe neurologic compromise when treated by rapid diagnosis and decompression of the spinal canal.

Ribozyme-mediated modulation of human O6-methylguanine-DNA methyltransferase expression

A synthetic oligonucleotide containing ribozyme sequences targeted to the 5' region of the human O6-methylguanine-DNA methyltransferase (MGMT) mRNA has been constructed. This ribozyme demonstrates cleavage activity in vitro in the presence of Mg2+. To determine whether this ribozyme can function in vivo, HeLa CCL2 cells were transfected with a mammalian expression vector containing the ribozyme sequence. Following selection and expansion of individual transfectants, a stable clone was isolated that lacks both MGMT mRNA and protein. Molecular analysis of this cell line indicates that in vivo cleavage of MGMT mRNA is responsible for the lack of MGMT activity.

Shapes of cells spreading on fibronectin: measurement of the stellation of BHK21 cells induced by raising cyclic AMP, and of its reversal by serum and lysophosphatidic acid

In common with many other animal cells in culture, BHK21, CHO and NIH-3T3 cells adopt bizarre stellate or arborized shapes when exposed, in the absence of serum, to agents which increase cytoplasmic cyclic AMP (cAMP). Dibutyryl cAMP, 3-isobutyl-1-methylxanthine, 5′-deoxy-5′-methylthioadenosine, cholera toxin and the invasive adenylate cyclase from Bordetella pertussis all induce similar shapes. Time lapse video recording of BHK21 cells spreading on fibronectin shows that stellate shapes are generated by outgrowth of neurite-like processes led by small fans of ruffling membrane. These structures stain strongly for F actin, and their outgrowth is completely inhibited by cytochalasin D. Thus if stellation is caused by microfilament depletion, this must be selective for subsets of microfilaments. We have quantified the shape changes of BHK21 cells using the parameter dispersion. They are prevented by low concentrations (1% by volume and below) of bovine sera. The inhibitory component of foetal bovine serum acts humorally, behaves as a macromolecule and is itself inhibited by suramin, but platelet-derived growth factor, insulin, vasopressin and bradykinin are inactive. The inhibitory activity of serum may be due to phospholipids, since it can be replaced by lysophosphatidic acid in the presence of serum albumin.

Chronic donor site pain complicating bone graft harvesting from the posterior iliac crest for spinal fusion

To explore the relationship between surgical approach and chronic posterior iliac crest donor site pain, 151 bone graft harvests with follow-up periods longer than 1 year were evaluated using a detailed questionnaire and follow-up clinical visits. There was no difference in the incidence of chronic donor site pain between harvests performed through the primary midline incision versus a separate lateral oblique incision (28 vs 31%). Twice as many donor sites harvested for reconstructive spinal procedures were reported as having chronic pain as compared with those harvested for spinal trauma, regardless of approach used (39 vs 18%). The association of chronic donor site pain with residual back pain was also greater in the spinal reconstructive group. Thus, it appears that incidence of chronic donor site pain is more dependent on diagnosis than on surgical approach.

Predictors of participation in a school-based anti-tobacco activism program

This study investigated the predictors of participation in a school-based, anti-tobacco activism program. Subjects in this study consisted of 7th grade students participating in the intervention component of Project S.H.O.U.T., a tobacco use prevention program in San Diego County, California. In the activism component, a newsletter containing an activism contest was distributed to each student. Small prizes were awarded to contest winners at each school. "Activism" included letter and petition writing, anti-tobacco poster contests, merchant education, peer surveys and magazine subscription cards. A total of 170 students participated in the activities, with 81.1 percent participating two or more times. Of those who participated, 59 percent were female and 60 percent were White, non-Hispanic. Two sets of logistic analyses were conducted. Variables such as SES, gender, ethnicity, friends' tobacco use and parental tobacco use were used to predict participation in activism activities. The choice of variables was intended to provide information regarding activism participation in reference to known tobacco risk factors. Results of the first analysis indicated that students with a higher SES, and in an urban vs. rural location were more likely to participate in the activism activities. The second analysis used the same set of characteristics to predict "ever-use" of tobacco. Results of this analysis indicated that male gender, low grades, White, non-Hispanic ethnicity, friends' and parents' tobacco use were positively associated with tobacco experimentation.

Anatomic consideration for sacral screw placement

Instrumentation of the lumbosacral spine increasingly involves screw fixation to the sacrum. Recommended locations and techniques for screw placement vary, particularly when bicortical purchase of the sacrum is performed. The purpose of this study was to describe the critical anatomy and potential injuries to neurovascular and visceral structures anterior to the sacrum. Lack of awareness can lead to life-threatening complications. The study included 22 fresh human cadavers with no prior spinal surgery. Specimens were placed in a prone position, and the lumbosacral spine was exposed. Two 6.5-mm screws were inserted using one of two techniques, respectively: Starting just inferior to the S1 facet one screw was angled 25 degrees caudally and 30 degrees laterally; in the second technique, lateral inclination was increased to 45 degrees. In addition, all specimens had screws placed in the S2 pedicles. An anterior dissection was performed to allow evaluation of the neurovascular and visceral structures at risk for injury by, or adjacent to, the screw tips. All significant neurovascular structures in the area of concern were constant in position. The internal iliac vein and the lumbosacral nerve trunk were most at risk for injury by the 30 and 45 degrees laterally directed screws. The sigmoid colon, though close to the S2 screw, was protected by its mesentery. Screws placed in the S1 pedicle were least likely to injure the neurovascular bundle. A lateral and a midline safe zone were identified.

Fractures of the atlas

Thirty-four patients who had fractures of the atlas (the first cervical vertebra) were reviewed at an average follow-up of 4.5 years. Seventeen patients had bilateral fracture of the posterior arch of the first cervical vertebra. Eight were treated with immobilization in a cervical orthosis, with no long-term problems secondary to the injury. Nine of these patients had additional fractures in the first and second cervical vertebral complex, complicating the management of the fractures of the posterior arch. Two of the nine patients died, and the treatment of the other seven was dependent on the additional fractures. A second group of six patients had a fracture in the area of the lateral mass, with one fracture just anterior to or within the anterior portion of the lateral mass of the first cervical vertebra and a second fracture posterior to the lateral mass of the first cervical vertebra on the same side; resultant asymmetrical displacement of the lateral masses was seen on the open-mouth roentgenogram that was made for each patient. A third group of eleven patients sustained a Jefferson, or burst, fracture of the first cervical vertebra. These patients had either four fractures (two in the anterior arch and two in the posterior arch) or three fractures (one in the anterior arch and two in the posterior arch). Spreading of the lateral masses was relatively symmetrical on the open-mouth roentgenogram. Patients who had fractures with displacement of two to seven millimeters were treated with immobilization in a halo vest. Patients who had fractures with severe spreading of the lateral masses (more than seven millimeters) were treated with reduction of the lateral masses by axial traction until healing of the arch had occurred. No atlanto-axial instability was evident in any patient at follow-up.

Traumatic lesions of the occipitoatlantoaxial complex

Injuries of the occipitoatlantoaxial complex are relatively rare but form a group of ligamentous and bony lesions that may unnecessarily confuse the clinician. Since fractures of the dens and traumatic spondylolisthesis of the axis have been well described in a number of large series, this article concentrates on the lesions less frequently seen and described. The ligamentous injuries are occipitoatlantal dislocation, rupture of the transverse ligament, and atlantoaxial rotatory fixation. The bony injuries are fractures of the occipital condyles, atlas, and the lateral masses of C2. The incidence, diagnostic criteria, and treatment modalities depend on the nature of localization of the traumatic lesions.

Prevention of tobacco use among adolescents in public schools in San Diego County, U.S.A

Project S.H.O.U.T. (which stands for "Students Helping Others Understand Tobacco") is a tobacco-use prevention project funded by the United States National Cancer Institute for preventing the use of cigarettes and smokeless tobacco (snuff and chewing tobacco) in public schools in San Diego County, California. Based on principles of behavior modification, Project S.H.O.U.T. teaches students how to anticipate and overcome negative peer pressure to use tobacco and reinforces them for having done so. Preliminary results indicate that the prevalence of tobacco use among students receiving peer pressure resistance skills training was somewhat but not statistically significantly lower than the control group after one year of intervention. In addition, students in a third lottery condition, who were reinforced for simply not using tobacco, showed lower prevalence rates compared to controls. Additional support for the efficacy of the intervention program was provided by the refusal skills assessment test, which indicated that students exposed to the intervention were able to refuse tobacco offers more effectively than the control students. Our results indicate that tobacco use prevention experts should do more than provide decision-making and behavioral skills for resisting tobacco use, but should also reinforce the non-use of tobacco.

Pneumocystis carinii antigenemia in acquired immunodeficiency syndrome

The present study was conducted to determine the prevalence and significance of Pneumocystis carinii antigenemia in patients with acquired immunodeficiency syndrome (AIDS) and clinically or invasively diagnosed P. carinii pneumonitis. Single serum specimens from 20 AIDS patients invasively examined for P. carinii organisms and 106 AIDS patients with a clinical diagnosis only of P. carinii pneumonitis were blindly tested for P. carinii antigenemia by a counterimmunoelectrophoresis assay. In the 20 specimen-documented cases, the antigen test demonstrated a sensitivity of 75% and a specificity of 90%. The positive predictive value of the test was 90%, while the negative predictive value was 70%. In AIDS patients with specimen-documented P. carinii pneumonitis, the prevalence of P. carinii antigenemia coincided almost exactly with the prevalence of positive invasively obtained specimens (60 and 59%, respectively). In patients with a clinical diagnosis only of P. carinii pneumonitis, half as many (30%) were found to exhibit antigenemia. Sequential P. carinii antigen titers determined by a new latex agglutination technique on three AIDS patients with specimen-documented P. carinii pneumonitis demonstrated the influence of specific therapy upon P. carinii antigenemia and its potential prognostic application.

Bilateral facet dislocations in the thoracolumbar spine

Bilateral facet dislocation represents approximately 11% of all thoracolumbar spine injuries requiring surgical stabilization. The injury can be caused by either flexion distraction (29/30 cases) or by pure distraction (1/30). Recognition of the injury is possible on plain radiographs, and confirmed by the empty facet sign on the computed tomography (CT) scan. In contradistinction to other major spine injuries, the majority of patients present with complete neurologic lesions (21/30). Recovery of patients with incomplete lesions is frequent (5/6); however, recovery from complete lesions did not occur. Compression instrumentation is recommended for patients with complete lesions because it is stable and requires no external immobilization. Distraction instrumentation that imparts significant extension is advised for patients with incomplete lesions. It is safe and reliable, and eliminates the posterior bulging of the injured disc that can occur with compression. For low lumbar injuries where compression is desirable in order to achieve the shortest possible instrumentation, a discectomy is recommended.

Severe open tibial fractures. Results treating 202 injuries with external fixation

Grade III open tibial fractures are known for frequent complications and poor clinical results, yet published series are few and cite conflicting results. To address this dilemma, the authors report a prospective study of 202 consecutive Grade III tibial fractures. All injuries were treated under protocol at the authors' university with primary external fixation and serial debridement. Equinus deformity was prevented with a new tibiometatarsal frame extension. Severe injuries crossing the ankle or knee were temporarily stabilized with external fixation across these joints. Staged reconstruction of soft tissue and then bone was undertaken for 176 of these tibias in patients who survived their multiple injuries. Reconstructive procedures included skin grafts in 57%, muscle flaps in 32%, and bone grafts in 28%. Gastrosoleus myocutaneous flaps were successful in 92% of cases versus 66% for free flaps. Late follow-up data were obtained for 171 (97%). Infection occurred in 15% and led to amputation in 7%. The infection rate was reduced to 9% in the second half of the series largely by removal of all necrotic bone prior to wound coverage. Angulation (greater than 10 degrees) in 9% and delayed union were lessened with early posterolateral grafting followed by progressive fracture loading in the fixator. A 9% incidence of pin tract drainage or loosening was reduced with predrilling and diaphyseal half pins. The time to fixator removal averaged 87 days. Ninety-three percent of the fractures united (median time, nine months) but healing times varied widely according to the amount of tissue injury and bone loss. Eighty-nine percent had satisfactory late clinical function. Results from this study, the largest series of open Grade III tibial fractures reported to date, suggest that successful staged reconstruction is now a reasonable expectation for most of these severe injuries.

Pneumocystis carinii serologic study in pediatric acquired immunodeficiency syndrome

Pneumocystis carinii antigen and IgG antibody profiles were prepared on 17 pediatric patients with acquired immunodeficiency syndrome (AIDS) with pneumonia who were examined by a variety of invasive methods for P carinii organisms. Overall, the accuracy of the antigen assay in invasively examined pediatric patients with AIDS with pneumonia was 94% (sensitivity, 100%; specificity, 90%), as antigen and invasive test results agreed in 16 of 17 patients. No statistically significant differences in IgG titer were observed between controls and patients invasively examined for P carinii, whether the organism was observed in the specimen or not. Since 38% of all serum samples referred were derived from "blood-borne" cases of AIDS, including patients who contracted AIDS as a result of both transfusion and hemophilia A, this suggests that P carinii pneumonia or P carinii pneumonia- like pneumonias may be more common in these individuals.

Evidence for depressed humoral immunity to Pneumocystis carinii in homosexual males, commercial plasma donors, and patients with acquired immunodeficiency syndrome

Heterosexual controls were found to have significantly higher titers of immunoglobulin G antibody to Pneumocystis carinii than did patients with the acquired immunodeficiency syndrome (AIDS) and P. carinii pneumonitis, human immunodeficiency virus (HIV) antibody-positive or -negative homosexual male "gay bar" patrons, and HIV antibody-positive or -negative commercial plasma donors. The T-helper/T-suppressor lymphocyte ratios of HIV antibody-negative homosexual male gay bar patrons were slightly depressed (mean = 1.31 +/- 0.54) compared with those of heterosexual controls (mean = 1.79 +/- 0.32). In addition to other recognized factors, preexisting humoral as well as cell-mediated immune deficits before infection with HIV may help to explain the prevalence of and morbidity and mortality associated with P. carinii pneumonitis in AIDS patients.

Preliminary studies on the development of a vaccine for Pneumocystis carinii. I. Immunological and biochemical characterization

Initial progress has been made toward the development of an experimental vaccine or immunostimulant for Pneumocystis carinii. Antigen derived from cell culture propagated P. carinii proved to be a potent immunogen in the rabbit and antibody thus produced demonstrated identity with intact murine and human lung-derived P. carinii organisms. Reactivity of the antibody with P. carinii soluble antigen in the blood of rats and human subjects with P. carinii pneumonitis (PCP) was demonstrated by the Ouchterlony technique, by counterimmunoelectrophoresis (CIE) and by latex particle agglutination (LPA). Murine-derived P. carinii antigen was utilized in an enzyme-linked immunosorbent assay (ELISA) for anti-P. carinii IgG and IgM produced in immunized rabbits and for human IgG antibody against P. carinii. Preliminary biochemical analysis of whole and solubilized cysts has been carried out, as well as slab gel electrophoresis and immunoblot profiling of solubilized organisms and naturally-occurring P. carinii antigen(s) in the blood of humans and rats with PCP. These studies represent an initial step toward the development of a vaccine or immunostimulant against PCP.

Pure thoracolumbar facet dislocation: clinical features and CT appearance

The use of computed tomography (CT) in demonstrating pure dislocations of the thoracolumbar facets and in predicting the prognosis of this injury was evaluated and compared with radiography retrospectively. The records of 29 patients with pure thoracolumbar bilateral facet dislocation who were admitted to the trauma unit over a 4-year period were reviewed. Twenty-two patients (76%) had a complete neurologic loss that remained complete following immediate surgical stabilization; five (17%) had an incomplete neurologic loss, and two (7%) were normal neurologically. Plain radiographs of the spine, including anteroposterior and lateral views, documented the level and type of fracture but failed to depict the full extent of bony ad soft-tissue injuries. CT provided essential additional information, particularly regarding the status of the posterior elements of the vertebrae and the adequacy of the spinal canal. Pure thoracolumbar facet dislocations have a characteristic appearance on axial CT scans. Sagittal reformation through CT is essential in the evaluation of this type of spinal injury.

External fixation arthrodesis of the ankle joint following trauma

Arthrodesis is currently the treatment of choice for symptomatic degenerative arthropathy of the ankle. Thirty-seven patients underwent arthrodesis for post-traumatic disorders using either a Hoffmann external fixator or a Calandruccio frame. There was degenerative joint disease in 19 (51%), septic arthritis in 11 (30%), severe comminution in five (14%), and uncontrollable equinus in two (5%). The patients were divided into two groups. Twenty-six (70%) were considered to have sustained high energy open or comminuted injuries and 11 (30%), low energy injuries. Twenty-nine (78%) achieved a radiologic fusion following one operation. Four eventually united with further surgery for a final arthrodesis rate of 89%. In the high energy group 18 of 26 (69%) achieved primary fusion. Four united with additional surgery for a final arthrodesis rate of 85%. Two of these required subsequent amputations and two others, a triple arthrodesis which also failed to control chronic pain. Thus, a total of 18 of the 26 patients (69%) achieved a successful result. Also included in the high energy group were three patients with uncontrolled sepsis who underwent amputation before union occurred and one with a painful non-union. All 11 of the patients (100%) who originally sustained low energy injuries achieved a successful arthrodesis. The most common complication was in pin tract infection requiring incision, drainage, and oral antibiotics in 16 patients (43%). None of these progressed to chronic osteomyelitis.

Early rod-sleeve stabilization of the injured thoracic and lumbar spine

The rod-sleeve method provides adjustable corrective forces in all directions so as to accomplish anatomic alignment and three-dimensional rigid fixation for acute spinal injuries. The authors studied a prospective series of 135 consecutive cases treated with this new technique. Results showed improved indirect canal decompression and neurologic recovery, few complications, and greater maintenance of correction than previously reported.

Complications in the treatment of acute spinal injury

Complications may occur during any phase of the treatment process for acute spinal injuries. An awareness of the most common problems is the most powerful tool that the physician has to prevent him or her from repeating at least some of the errors of others.

Treatment of injuries in the C1-C2 complex

Trauma to the upper cervical spine results in injuries to the C1-C2 complex that may differ significantly from those in the lower cervical spine. Five major types of injuries occur, and their treatment is based on an understanding of the mechanisms of injury.

The management of traumatic spondylolisthesis of the axis

Fifty-two patients with traumatic spondylolisthesis of the axis were admitted to the University of Maryland Spinal Injury Center between 1977 and 1982. There were fifteen Type-I fractures, twenty-nine Type-II fractures, three Type-IIa fractures, and five Type-III fractures. Associated neurological deficits were found in only four patients, although unassociated neurological deficits such as closed head injury were seen in eleven patients. Thirteen patients had other fractures of the cervical spine. Type-I fractures were stable injuries and were treated with collar protection. Most Type-II injuries were reduced with the patient in halo traction, and then immobilization in a halo vest was used. Type-IIa injuries, as they showed increased displacement in traction, were reduced with gentle extension and compression in a halo vest. Type-III injuries were grossly unstable and required surgical stabilization. All of the fractures healed, although the use of early halo-vest immobilization for displaced fractures resulted in significant residual deformity. The radiographic patterns of the fracture types and the resulting data on clinical stability suggested a correlation between the fracture type and the mechanism of injury. Type-I injuries resulted from a hyperextension-axial loading force; Type-II injuries, from an initial hyperextension-axial loading force followed by severe flexion; Type-IIa injuries, from flexion-distraction; and Type-III injuries, from flexion-compression.

Immediate closed antegrade Ender nailing of femoral fractures in polytrauma patients

Fifty-four trauma patients with 61 femoral fractures stabilized within the first 24 hours of admission by closed antegrade Ender nailing were included in this study. This technique involves the insertion of Ender nails from a portal at the proximal end of the femur through the piriformis fossa. The curved distal ends of the nails were distributed throughout the distal femur to achieve greater purchase in the enlarged medullary canal of the distal fragment. This technique was used in one proximal, 20 midshaft, 37 distal, and three segmental fractures. There were 51 closed fractures, eight Grade I open, and two Grade II open fractures. The average age of the patient was 26 years, and the majority had polytrauma. The operative procedure was well tolerated by this group of patients. Pulmonary care was improved by avoidance of traction and enhanced capability for mobilization. Forty-two patients with 49 femoral fractures were available for complete follow-up. Forty-five fractures healed with the average time to appearance of bridging callus being 33 days, and average time to full union remodeled callus being 5.9 months. There were four nonunions, one delayed union, and eight malunions. There were nail protrusions in 22 cases (19 proximal and three distal). Fourteen patients required a second operation for reimpaction of the protruding nails or premature nail removal. These results were inferior to those obtained with the use of the retrograde Ender nailing technique or the Kuntscher nail. This technique should be used only if other techniques are unavailable or inappropriate, and only for stable, noncomminuted fractures.(ABSTRACT TRUNCATED AT 250 WORDS)

Enzymatic adaptation in ligaments during immobilization

Ligaments are a composite of fibroblasts and collagen in a proteoglycan matrix. Seventy-five percent of the organic solid is collagen and 23% is proteoglycan. Fibroblasts are responsible for the overall composition of the ligament, that is the synthesis and the degradation of macromolecular components. Like muscle and bone, ligaments are dynamic, undergoing hypertrophy with exercise and atrophy with immobilization. This paper reviews the structure and composition of ligaments and discusses the cellular events responsible for atrophy of ligaments with immobilization. As an experimental model, one knee of New Zealand White rabbits was immobilized with a pin. After 2, 4, and 8 weeks of immobility, the medial collateral ligaments were isolated and enzyme analysis was performed. Gross and microscopic changes were apparent after 2 weeks. As for enzyme changes, lactic dehydrogenase and malic dehydrogenase decreased in activity. The lysosomal hydrolases responsible for glycosaminoglycan degradation increased in activity, suggesting that enzymatic adaptations mediate the physical and chemical changes in the ligament. The cells switch from an anabolic synthetic state to a catabolic, degradative state during immobility. It would seem from the biochemical viewpoint that, whenever possible, cast-bracing and functional splints may be preferable to rigid plasters in many sports-related ligamentous injuries.

Pneumocystis carinii infection in germ-free rats: implications for human patients

Pneumocystis carinii infections have been detected both serologically and histologically in untreated, germ-free and conventional rats killed immediately upon arrival from two commercial sources. Pneumocystis antigenemia was detected by counterimmunoelectrophoresis (CIE) and antibody was titered by indirect immunofluorescence. The data suggest that 1) P. carinii is enzootic in certain rat colonies; 2) in utero transmission is a distinct possibility; and 3) paucity of cysts does not rule out P. carinii, as trophozoites predominate in early or sub-clinical infections. Histologic data support the validity of CIE for noninvasive detection of P. carinii antigen. Infection with this agent may be missed by basing diagnosis upon the presence of cyst forms alone, and it may be more common than previously supposed. These data have significant implications for the natural history, diagnosis, and epidemiology of P. carinii with regard to the human host.