Risk factors for and consequences of difficult fetal extraction in emergency caesarean section. A retrospective registry-based cohort study

INTRODUCTION

This study aimed to assess risk factors for difficult fetal extraction in emergency caesarean sections, focusing on top-up epidural anesthesia compared to spinal anesthesia. Additionally, this study addressed consequences of difficult fetal extraction on neonatal and maternal morbidity.

MATERIAL AND METHODS

This retrospective registry-based cohort study included 2,332 of 2,892 emergency caesarean sections performed with local anesthesia during 2010-2017. Main outcomes were analyzed by crude and multiple adjusted logistic regression providing odds ratios.

RESULTS

Difficult fetal extraction was found in 14.9% of emergency caesarean sections. Risk-factors for difficult fetal extraction included top-up epidural anesthesia (aOR:1.37[95 %CI 1.04-1.81]), high pre-pregnancy BMI (aOR:1.41[95 %CI 1.05-1.89]), deep fetal descent (ischial spine: aOR:2.53[95 %CI 1.89-3.39], pelvic floor: aOR:3.11[95 %CI 1.32-7.33]), and anterior placental position (aOR:1.37[95 %CI 1.06-1.77]). Difficult fetal extraction was associated with increased risk of low umbilical artery pH 7.00-7.09 (aOR:3.50[95 %CI 1.98-6.15]) pH ≤ 6.99 (aOR:4.20[95 %CI 1.61-10.91]), five-minute Apgar score ≤ 6 (aOR:3.41[95 %CI 1.49-7.83]) and maternal blood loss (501-1,000 ml: aOR:1.65[95 %CI 1.27-2.16], 1,001-1,500 ml: aOR:3.24[95 %CI 2.24-4.67], 1,501-2,000 ml: aOR:3.94[95 %CI 2.24-6.94] and ≥ 2001 ml: aOR:2.76[95 %CI 1.12-6.82]).

CONCLUSION

This study identified four risk factors for difficult fetal extraction in emergency caesarean section: top-up epidural anesthesia, high maternal BMI, deep fetal descent and anterior placental position. Additionally, difficult fetal extraction was associated with poor neonatal and maternal outcomes.

Postoperative infections after non-elective cesarean section - a retrospective cohort study of prevalence and risk factors at a single center in Denmark administering prophylactic antibiotics after cord clamping

BACKGROUND

Mothers giving birth by non-elective cesarean section have considerably higher risk of developing postoperative infection, than mothers giving birth by elective cesarean section. Meta-analyses have shown that the risk of infection is reduced when administering antibiotics at least 30 min prior to skin incision rather than after cord clamping. If given prior to incision, antibiotics are present in the neonatal bloodstream for up to 24 h after delivery, with early exposure to antibiotics potentially disturbing development of the gut microbiome. We aimed to retrospectively assess the prevalence of postoperative infection after non-elective cesarean section at a single labor ward administering antibiotics after cord clamping, additionally investigating risk factors for developing postoperative infections.

METHODS

In this retrospective cohort study, we included a total of 2,725 women giving birth by non-elective cesarean section in 2010-2017 with a review of records for prenatal risk factors, labor management, and perinatal outcomes. The primary outcomes were a main composite infection of development of either endometritis, surgical-site infection, or sepsis in conjunction with a relevant antibiotic prescription. Secondary outcomes included infection of unknown focus, mastitis, urinary tract infection, and pneumonia.

RESULTS

A total of 88 patients developed a main composite infection (3.2%). These infections subdivide into endometritis (n = 37/2725, 1.4%), surgical-site infection (n = 35/2725, 1.3%) and sepsis (n = 15/2725, 0.6%). We found a high body mass index (aOR = 3.38, 95%CI 1.93-5.92) and intrapartum fever (aOR = 2.26, 95%CI 1.22-4.59) to be independent risk-factors for developing postoperative infection after non-elective cesarean section. Furthermore, we found delivery by a more expedient emergency grade 2 cesarean section (aOR = 0.61 95%CI 0.37-0.998) compared to grade 3 to be a protective factor for developing postoperative infection after non-elective cesarean section.

CONCLUSION

In a labor ward administering antibiotics after cord clamping at non-elective cesarean births, we find a low prevalence of main composite infections when compared to estimates from meta-analyses on the topic. We conclude that administration of prophylactic antibiotics after cord clamping appears to result in acceptable rates of postoperative infection and avoids transplacental-transmission of antibiotics to the infant.

Using machine learning to identify quality-of-care predictors for emergency caesarean sections: a retrospective cohort study

OBJECTIVES

Emergency caesarean sections (ECS) are time-sensitive procedures. Multiple factors may affect team efficiency but their relative importance remains unknown. This study aimed to identify the most important predictors contributing to quality of care during ECS in terms of the arrival-to-delivery interval.

DESIGN

A retrospective cohort study. ECS were classified by urgency using emergency categories one/two and three (delivery within 30 and 60 min). In total, 92 predictor variables were included in the analysis and grouped as follows: 'Maternal objective', 'Maternal psychological', 'Fetal factors', 'ECS Indication', 'Emergency category', 'Type of anaesthesia', 'Team member qualifications and experience' and 'Procedural'. Data was analysed with a linear regression model using elastic net regularisation and jackknife technique to improve generalisability. The relative influence of the predictors, percentage significant predictor weight (PSPW) was calculated for each predictor to visualise the main determinants of arrival-to-delivery interval.

SETTING AND PARTICIPANTS

Patient records for mothers undergoing ECS between 2010 and 2017, Nordsjællands Hospital, Capital Region of Denmark.

PRIMARY OUTCOME MEASURES

Arrival-to-delivery interval during ECS.

RESULTS

Data was obtained from 2409 patient records for women undergoing ECS. The group of predictors representing 'Team member qualifications and experience' was the most important predictor of arrival-to-delivery interval in all ECS emergency categories (PSPW 25.9% for ECS category one/two; PSPW 35.5% for ECS category three). In ECS category one/two the 'Indication for ECS' was the second most important predictor group (PSPW 24.9%). In ECS category three, the second most important predictor group was 'Maternal objective predictors' (PSPW 24.2%).

CONCLUSION

This study provides empirical evidence for the importance of team member qualifications and experience relative to other predictors of arrival-to-delivery during ECS. Machine learning provides a promising method for expanding our current knowledge about the relative importance of different factors in predicting outcomes of complex obstetric events.

Reduction in maternal mortality in Denmark over three decades

INTRODUCTION

Women very rarely die during pregnancy and childbirth in Denmark. Although maternal deaths are registered worldwide, various studies indicate that underreporting does occur. This paper presents validated Danish register data for two periods between 1985 and 2017.

METHODS

Maternal deaths were identified from 1985 to 1994 and from 2002 to 2017 by linking four national health registers, death certificates and notifications from maternity wards. A group of obstetricians categorised and assessed all medical records, classifying each case by cause of death.

RESULTS

Linkage of four registers yielded valid data, leading to the identification of 143 maternal deaths in the abovementioned periods. From 1985-1994 there were 73 deaths and 618,021 live births, resulting in a maternal mortality rate of 11.8 per 100,000 live births with a non-significant 2% annual increase (95% confidence interval (CI): -6.0-11.0%). From 2002 to 2017 there were 70 maternal deaths and 999,206 live births, resulting in a maternal mortality rate of 7.0 per 100,000 live births (95% CI: 5.5-8.9) with a significant 9% annual decrease (95% CI: 4.0-14.0%).

CONCLUSIONS

Overall maternal mortality decreased in the course of the two periods (n = 33 years), with a significant decrease during the last period. This is suggested to be a result of multiple clinical and organisational improvements as discussed in the paper.

FUNDING

none.

TRIAL REGISTRATION

not relevant.

Social ties between team members affect patient satisfaction: a data-driven approach to handling complex network analyses

Research from outside the medical field suggests that social ties between team-members influence knowledge sharing, improve coordination, and facilitate task completion. However, the relative importance of social ties among team-members for patient satisfaction remains unknown. In this study, we explored the association between social ties within emergency teams performing simulated caesarean sections (CS) and patient-actor satisfaction. Two hundred seventy-two participants were allocated to 33 teams performing two emergency CSs in a simulated setting. We collected data on social ties between team-members, measured as affective, personal and professional ties. Ties were rated on 5-point Likert scales. In addition, participants' clinical experience, demographic data and their knowledge about team members' roles were surveyed. Perceived patient satisfaction was measured on a 5-point Likert scale. Data was analysed with a linear regression model using elastic net regularization. In total, 109 predictor variables were analysed including 84 related to social ties and 25 related to clinical experience, demographics and knowledge test scores. Of the 84 variables reflecting social ties, 34 (41%) had significant association with patient satisfaction, p < 0.01. By contrast, a significant association with patient satisfaction was found for only one (4%) of the 25 variables reflecting clinical experience, demographics and knowledge of team roles. Affective ties and personal ties were found to be far more important predictors in the statistical model than professional ties and predictors relating to clinical experience. Social ties between emergency team members may be important predictors of patient satisfaction. The results from this study help to enhance our conceptual understanding of social ties and their implications for team-dynamics. Our study challenges existing views of team-performance by placing emphasis on achieving collective competence through affective and personal social ties, rather than focusing on traditional measures of expertise.

From prescription to guidance: a European framework for generic competencies

In postgraduate medical education, required competencies are described in detail in existing competency frameworks. This study proposes an alternative strategy for competency-based medical education design, which is supported by change management theories. We demonstrate the value of allowing room for re-invention and creative adaptation of innovations. This new strategy was explored for the development of a new generic competency framework for a harmonised European curriculum in Obstetrics and Gynaecology. The generic competency framework was developed through action research. Data were collected by four European stakeholder groups (patients, nurses, midwives and hospital boards), using a variety of methods. Subsequently, the data were analysed further in consensus discussions with European specialists and trainees in Obstetrics and Gynaecology. These discussions ensured that the framework provides guidance, is specialty-specific, and that implementation in all European countries could be feasible. The presented generic competency framework identifies four domains: 'Patient-centred care', 'Teamwork', 'System-based practice' and 'Personal and professional development'. For each of these four domains, guiding competencies were defined. The new generic competency framework is supported by European specialists and trainees in Obstetrics and Gynaecology, as well as by their European stakeholders. According to change management theories, it seems vital to allow room for re-invention and creative adaptation of the competency framework by medical professionals. Therefore, the generic competency framework offers guidance rather than prescription. The presented strategy for competency framework development offers leads for implementation of competency-based medical education as well as for development of innovations in postgraduate medical education in general.

Making the best of the worst: Care quality during emergency cesarean sections

Objective

This study aimed to identify factors influencing mothers’ and their partners’ perceptions of care quality, and to identify associated clinical factors.

Methods

Questionnaires were developed based on eight interviews with couples after emergency Cesarean Sections (ECS). The internal structure of the questionnaires was examined using Rasch analysis. Cronbach’s alpha was calculated to evaluate internal consistency of questionnaire items. Finally, associations between questionnaire scores and ECS characteristics were determined.

Results

Thematic analysis of interview data demonstrated that team-dynamics, professionalism, information, safety, leadership and mother-child continuity of care are important to patient- perceived quality of care. Questionnaire responses from 119 women and 95 partners were included in the validation and demonstrated satisfying fit to the Rasch model. The questionnaires had acceptable internal consistency with Cronbach’s alpha 0.8 and 0.7 for mothers and partners, respectively. Perceived quality of care was negatively associated with increasing urgency of the CS. Spearman rank correlation coefficients were -0.34 (p <0.001) and -0.32 (p = 0.004) for mothers and partners, respectively. Perceived quality of care differed significantly across CS indications for both mothers (p = 0.0006) and their partners (p<0.0001).

Conclusion

Team-dynamics, professionalism, information, safety, leadership and mother-child-continuity affect patients’ perceptions of care. Perceptions of care were highly influenced by CS indications and urgency.

[Medical students' evaluation of clinical departments can help low score departments to improve their effort]

Development of professional identity is essential for medical students to become good doctors. Introduction to the clinical setting, role models, reflection, structure, learning strategy and inclusion in community of practice are important factors. Four observations and 15 interviews were made and revealed big differences in educational practice in four different clinical departments. The departments with low evaluation scores need to improve their practice. Individual guidance inside the department, which adjusts for medical specialty, potentials and challenges, could initiate future progress.

Streptolysin O II. Relationship of Sulfyhdryl Groups to Activity

Streptolysin O (SO), a group A streptococcal toxin, exists in two forms, a reduced active state and an oxidized reversibly inactive state. Activity is measured by red blood cell hemolysis. SO is a labile toxin, and, with time, activity is irreversibly lost. The rate of activity loss is slowed by incubation with 0.1 m 2-mercaptoethanol or 0.01 m ethylenediaminetetraacetic acid (EDTA). The effect of EDTA can be reversed by excess MgSO(4). Reversibly oxidized SO is activated by cleavage of disulfide bonds. When the free sulfhydryl groups of the active SO are alkylated with iodoacetamide, complete and irreversible loss of activity results. Periodate (0.01 m) oxidation also causes complete loss of activity which may be due to oxidation of sulfhydryl groups. SO in the active form reacts with Fe(2+), Cu(2+), Ca(2+), and Mg(2+), causing loss of activity in various degrees depending on the ions and the concentration used. Ferric and cupric ions are most effective and cause loss of activity at concentrations on the order of 10(-4)m. The reversibly oxidized form of SO is not influenced by exposure to cupric ions (0.01 m), indicating that the reaction is only with the active form of SO, probably involving the free sulfhydryl groups. These groups may be responsible for the direct binding of the toxin to the target membrane or for the maintenance of the proper conformation for activity.

Prevalence of polyhydramnios at a Danish hospital – a population-based study

BACKGROUND

The purpose of this study was to determine the incidence of polyhydramnios, the related maternal and perinatal morbidity, and to estimate the association between perinatal outcome and the degree of polyhydramnios in a Danish population.

METHODS

The study population consisted of 168 women with singleton pregnancies and polyhydramnios diagnosed by ultrasound as a largest two-diameter pocket of > 50 cm2. Mild polyhydramnios defined as > 50 and < 100 cm2, and severe polyhydramnios defined as > or = 100 cm2. The background population consisted of 8,347 pregnant women from the same hospital. Outcome measures were compared using chi2 test or Fisher's exact test.

RESULTS

The incidence of polyhydramnios was 2%, with 66.7% of cases mild, and 33.3% were severe polyhydramnios. The study population had an increased risk of emergency (19 versus 10.5%, p<0.001) and elective (11.3 versus 5.0%, p<0.001) caesarean section, as well as perinatal death (1.2 versus 0.3%, p<0.05) compared to the background population. In cases of severe polyhydramnios, there was an increased risk of caesarean section (44.6 versus 23.1%, p<0.005), birth weight > 4,000 g (28.6 versus 14.3%, p<0.05), and need for neonatal care (8.9 versus 0.9%, p<0.01) compared to mild cases. Apgar score < 7, perinatal death and structural malformations only occurred in women with severe polyhydramnios.

CONCLUSION

It is reasonable to distinguish between mild and severe polyhydramnios regarding special attention and follow-up, as caesarean section and perinatal morbidity and mortality are related to the degree of polyhydramnios. A two-diameter pocket > or = 100 cm2 could be used to separate mild from severe cases.

Antibiotics versus placebo for prevention of postoperative infection after appendicectomy

BACKGROUND

Appendicitis is the most common cause of acute abdominal pain requiring surgical intervention. The cause of appendicitis is unclear and the mechanism of pathogenesis continues to be debated. Despite improved asepsis and surgical techniques, postoperative complications, such as wound infection and intraabdominal abscess, still account for a significant morbidity. Several studies implicate that postoperative infections are reduced by administration of antimicrobial regimes.

OBJECTIVES

This review evaluated the use of antibiotics compared to placebo or no treatment in patients undergoing appendectomy. Will these patients benefit from antimicrobial prophylaxis? The outcomes were described according to the nature of the appendix, as either simple appendicitis (including the non-infectious stage) and complicated appendicitis. The efficacy of different antibiotic regimens were not evaluated.

SEARCH STRATEGY

We searched The Cochrane Central Register of Controlled Trials (Cochrane Library 2005 issue 1); Pubmed ; EMBASE; and the Cochrane Colorectal Cancer Group Specialised Register (April 2005). In addition, we manually searched the reference lists of the primary identified trials.

SELECTION CRITERIA

We evaluated Randomised Controlled Trials (RCTs) and Controlled Clinical Trials (CCTs) in which any antibiotic regime were compared to placebo in patients suspected of having appendicitis, and undergoing appendectomy. Both studies on children and adults were reviewed. The outcome measures of the studies were: Wound infection, intra abdominal abscess, length of stay in hospital, and mortality.

DATA COLLECTION AND ANALYSIS

Eligibility and trial quality were assessed, recorded and cross-checked by two reviewers.

MAIN RESULTS

Forty-five studies including 9576 patients were included in this review. The overall result is that the use of antibiotics is superior to placebo for preventing wound infection and intraabdominal abscess, with no apparent difference in the nature of the removed appendix. Studies exclusively on children and studies examining topical application reported results in favour to the above, although the results were not significant.

AUTHORS' CONCLUSIONS

Antibiotic prophylaxis is effective in the prevention of postoperative complications in appendectomised patients, whether the administration is given pre-, peri- or post-operatively, and could be considered for routine in emergency appendectomies.

Antibiotics versus placebo for prevention of postoperative infection after appendicectomy

BACKGROUND

Appendicitis is the most common cause of acute abdominal pain requiring surgical intervention. The cause of appendicitis is unclear and the mechanism of pathogenesis continues to be debated. Despite improved asepsis and surgical techniques, postoperative complications, such as wound infection and intraabdominal abscess, still account for a significant morbidity. Several studies implicate that postoperative infections are reduced by administration of antimicrobial regimes.

OBJECTIVES

The objective of this review is to evaluate the use of antibiotics with placebo or no treatment in patients undergoing appendectomy. Will these patients benefit from antimicrobial prophylaxis? The outcomes are described according to the nature of the appendix, as either simple appendicitis (including the non-infectious stage) and complicated appendicitis. This review do not attempt to compare the effect of different regimens. That clinical question is addressed in another review undertaken by Bleuer 1999.

SEARCH STRATEGY

We searched The Cochrane Controlled Trials Register (Cochrane Library 2002 issue 4); Pubmed, Embase and the Cochrane Colorectal Cancer Group Specialised Register (Up to October 2002). In addition we manually searched the reference lists of the primary identified trials.

SELECTION CRITERIA

We evaluated Randomised Controlled Trials (RCTs) and Controlled Clinical Trials (CCTs) in which any antibiotic regime were compared to placebo in patients suspected of having appendicitis, and undergoing appendectomy. Both studies on children and adults were reviewed. The outcome measures of the studies were: Wound infection, intra abdominal abscess, length of stay in hospital, and mortality.

DATA COLLECTION AND ANALYSIS

Eligibility and trial quality were assessed, recorded and cross-checked by two reviewers.

MAIN RESULTS

Forty-five studies including 9576 patients were included in this review. The overall result is that the use of antibiotics is superior to placebo for preventing wound infection and intraabdominal abscess, with no apparent difference in the nature of the removed appendix. Studies exclusively on children and studies examining topical application reported results in favour to the above although the results were not significant.

REVIEWER'S CONCLUSIONS

Antibiotic prophylaxis is effective in the prevention of postoperative complications in appendectomised patients, whether the administration is given pre-, peri- or post-operatively, and could be considered for routine in emergency appendectomies.

Smoking is a risk factor for recurrence of groin hernia

Studies of connective tissue from patients with inguinal hernia have shown that smoking may be associated with hernia formation due to a defective connective tissue metabolism. Whether smoking is a risk factor for recurrence, too, was examined in this study. From December 1990 through December 1995, 649 patients underwent hernia repair as open sutured repair (Cooper ligament or abdominal ring repair) or as open mesh repair. Five hundred forty-four eligible patients were evaluated for recurrence 2 years postoperatively. Association between recurrence and 17 patient-, disease-, and intraoperative variables were analyzed by multiple logistic regression. The results showed that smoking was significantly and independently associated with recurrence compared to nonsmoking [odds ratio (OR = 2.22; 95% confidence interval (95% CI) = 1.19-4.15)]. Open sutured repair compared to open mesh repair was the most significant predictor for recurrence (OR = 7.23; 95% CI = 3.01-17.37). Surprisingly, local anesthesia was associated with a higher risk of recurrence compared to general anesthesia (OR = 2.44; 95% CI = 1.19-5.09). Potential confounders and other risk factors for hernia recurrence such as age, alcohol consumption, previous surgery, and anatomical characteristics of the hernia were adjusted for in the analysis. In conclusion, smoking is an important risk factor for recurrence of groin hernia, presumably due to an abnormal connective tissue metabolism in smokers.

Heparins and mechanical methods for thromboprophylaxis in colorectal surgery

BACKGROUND

Colorectal surgery implies higher risk of postoperative thromboembolic complications as deep venous thrombosis (DVT) and pulmonary embolism (PE) than general surgery. The best prophylaxis in general surgery is heparin and graded compression stockings. No systematic review on combination prophylaxis or on thrombosis prophylaxis in colorectal surgery has been published.

OBJECTIVES

To compare the incidence of postoperative thromboembolism after colorectal surgery using prophylactic methods focussing on heparins and mechanical methods alone and in combinations.

SEARCH STRATEGY

Electronic searches was performed in MEDLINE, EMBASE back to 1970. Abstract books from major congresses were handsearched as were reference lists from previously performed reviews.

SELECTION CRITERIA

RCT or CCT comparing prophylactic interventions and/or placebo. Outcomes were ascending venography, 125 I-fibrinogen uptake test, ultrasound methods, pulmonary scintigraphy. Studies, using thermographic methods, other isotopic methods, plethysmographic methods, and purely clinical methods as the only diagnostic measure were excluded. 558 studies were identified - 477 were excluded. Only 3 of the identified studies focused exclusively on colorectal surgery. Studies of general surgery contain considerable numbers of colorectal patients. The authors of 66 studies in general and/or abdominal surgery were contacted for retrieving the results from the colorectal patients. Answers were received from very few. 19 studies entered this review.

DATA COLLECTION AND ANALYSIS

All studies and all data extraction were performed independently by at least two of the authors. Outcome was deep venous thrombosis and/or pulmonary embolism. Analysis of bleeding complications were unfeasible. 12 meaningful outcomes were analysed by means of the fixed effects model with Peto Odds Ratios.

MAIN RESULTS

Heparins versus no treatment: Any kind of heparincompared to no treatment or placebo (comparison 07.03, 11 studies). Heparin is better in preventing DVT and/or PE with a Peto Odds ratio at 0.32 (95% Confidence Interval 0.20-0.53) Unfractionated heparin versus low molecular weight heparin (comparison 08.03, 4 studies). The two treatments were found equally effective in preventing DVT and/or PE with a Peto Odds ratio 1.01 (95% Confidence Interval 0.67-1.52). Mechanical methods (comparison 10.3, 2 studies). The combination of graded compression stockings and LDH is better than LDH alone in preventing DVT and/or PE with a Peto Odds ratio at 4.17 (95% Confidence Interval 1.37-12.70).

REVIEWER'S CONCLUSIONS

The optimal prophylaxis in colorectal surgery is the combination of graduated compression stockings and low-dose unfractionated heparin. The unfractionated heparin can be replaced with low molecular weight heparin.

Mycobacterium avium induces HIV upregulation through mechanisms independent of cytokine induction

Mycobacterium avium complex (MAC) can induce upregulation of HIV. To investigate the underlying mechanisms, the effect of MAC-induced cytokines on HIV replication was first studied. Semiquantitative RT-PCR, followed by Northern blot analysis, revealed that mRNA encoding IL-6 and TNF-alpha was induced by MAC. However, production of these cytokines was undetectable and the addition of anti-cytokine antibodies to coinfected cells could only minimally block the MAC effect on HIV. Infection of U38 cells with MAC resulted in enhancement of HIV-1 LTR-CAT transcription. In addition, transient transfection of U937 cells with full-length wild-type as well as NF-kappaB-binding site-deleted mutant HIV-1 LTR-CAT constructs revealed that MAC-induced HIV-LTR CAT is NF-kappaB dependent. These findings, together with our previous work, indicate that MAC-induced cytokine expression increases the formation of NF-kappaB, which in turn enhances HIV-1 LTR-CAT transcription. However, additional factor(s) yet to be elucidated may play a more significant role in MAC-mediated HIV-upregulation.

Biodegradable implants from poly-(alpha-hydroxy acid) polymers for isoniazid delivery

SETTING

In vitro and in vivo study of an isoniazid (INH) drug delivery system.

OBJECTIVE

To develop a system for the treatment of tuberculosis using a subcutaneous polymer implant with a large drug load released slowly over a long period. INH delivery by biodegradable poly-(alpha-hydroxy acid) polymers was evaluated using ground polymer and compression molded implants.

DESIGN

Rate of drug release and structural stability of the implant in an aqueous environment were measured, as were in vivo evaluations of the duration of measurable levels of INH in serum and urine.

RESULTS

Factors that influenced the suitability of an implant in an in vitro system included polymer molecular weight and crystallinity, polymer and drug particle size, drug loading dose, and press temperature and pressure. The implant characteristics that most closely approached optimal conditions include a polymer of 100% L-lactide with low intrinsic viscosity, polymer particle size <75 micron, and INH particle = 126-180 micron, INH loading dose not to exceed 46%, and press conditions of 70 degrees C and 345000 kPa. Studies of subcutaneous implants in rabbits and baboons show that INH is released from the implant for 15 to 26 weeks.

CONCLUSIONS

An INH-containing polymer was developed that was structurally stable in an aqueous environment and that released INH over a period of at least 15 weeks. Studies with infected animals will be necessary to determine the dose required for prophylaxis and treatment of active disease.

Mycobacterium avium complex activates nuclear factor kappaB via induction of inflammatory cytokines

A variety of microorganisms has been reported to directly induce NF-kappaB, a critical step in the regulation of genes involved in the cellular immune response. In this study, we demonstrate that proinflammatory cytokines such as tumor necrosis factor alpha (TNFalpha) produced upon activation by the Mycobacterium avium complex (MAC) preceed NF-kappaB activity in U937, a human monocytoid cell line. MAC induction of TNFalpha mRNA expression was detected within 15 min after MAC infection, whereas enhanced NF-kappaB binding activity was not detected until 90 to 120 min postinfection. Supershift analysis revealed increased p50 in the MAC-induced NF-kappaB binding complexes. Consistent with an autocrine mechanism, anti-TNFalpha antibody and dexamethasone, a known cytokine inhibitor, both completely suppressed the effect of MAC on the induction of NF-kappaB. Taken together, these findings suggest that exposure of monocyte cell membranes to MAC induces endogenous TNFalpha, which in turn enhances NF-kappaB binding activity. The rapid induction of TNFalpha may be important in the initial host response to MAC infection.

Information processing and antiretroviral therapy in HIV-1 infection

Computerized reaction time (RT) tasks are sensitive measures of subclinical HIV-related mental slowing. We previously reported that nondemented HIV-seropositive patients on antiretroviral therapy at the time of testing had faster choice RTs compared to matched untreated seropositive participants. In the present study, we evaluated the performance of 163 nondemented HIV-seropositive participants on a reaction time version of the Stroop task as a function of antiretroviral status. Persons on antiretroviral therapy at the time of testing had significantly faster reaction times than untreated individuals, although treated asymptomatic participants showed significantly less Stroop interference than treated symptomatic participants. These effects could not be attributed to differences in demographic variables, disease status, substance abuse, or psychological distress. These data indicate that central information processing is faster for patients treated with antiretroviral compounds compared to untreated patients, and suggest that reaction time tasks may have significant potential utility in clinical trials of neuroprotective compounds.

[Prostate-specific antigen, acid phosphatases and rectal exploration in the diagnosis of prostatic cancer]

Eleven hundred and seven patients referred for urological evaluation including measurement of serumprostate specific antigen (PSA) measurement are reviewed. Prostate cancer was diagnosed in 105 patients. PSA was found to be superior to prostatic acid phosphatase in the discrimination between prostate cancer and benign prostatic conditions. In 105 patients with newly diagnosed prostate cancer, scintigraphic evidence of osseous metastases was found in thirty-seven. No patients with a serum PSA value less than three times the upper normal limit of the assay had a positive bone scan. Isotope bone scan can be omitted in these patients, if they are not considered candidates for curative treatment.

Transcriptional regulation of hydroxypyruvate reductase gene expression by cytokinin in etiolated pumpkin cotyledons

To understand the mechanisms by which the expression of a specific gene is modulated by cytokinin, the regulation of hydroxypyruvate reductase (HPR) transcript levels by N6-benzyladenine (BA) in etiolated pumpkin (Cucurbita pepo L. cv. Halloween) cotyledons was investigated. A pumpkin HPR cDNA was generated by reverse transcriptase-polymerase chain reaction and its nucleotide sequence was determined. An antisense HPR RNA was prepared for RNase protection analysis of HPR-mRNA expression patterns in the cotyledons of dark-grown pumpkin seedlings. Treatment of the cotyledons with BA was shown to modulate HPR mRNA levels in a dose- and time-dependent manner. Similarly, nuclear run-on studies showed that the rate of transcription was also enhanced by BA treatment of the cotyledons. These results suggest that the enhancement of HPR mRNA by cytokinin is, at least in part, at the level of transcription.

Human immunodeficiency virus and Mycobacterium avium complex coinfection of monocytoid cells results in reciprocal enhancement of multiplication

Disseminated Mycobacterium avium complex (MAC) infection is an important opportunistic infection in AIDS patients. Because cells of macrophage lineage are targets for both human immunodeficiency virus (HIV) and MAC, the monocytoid cell line U937 was coinfected with both pathogens. Coinfected cultures had increased HIV replication (more than threefold at day 6) and an increased percentage of HIV-infected cells compared with cultures infected only with HIV. The kinetics of HIV replication were significantly increased in this coinfection system as measured by flow cytometry. When cells were infected concurrently, the rate of intracellular growth of MAC was not significantly affected. However, cells preinfected with HIV before infection with MAC showed significant enhancement of MAC growth compared with control cells. The kinetics of cell death were also increased in the coinfection system compared with singly infected controls. Thus, coinfection of monocytoid cells with HIV and MAC in vitro results in reciprocal enhancement of multiplication.

Isolated myocardial abscess causing coronary artery rupture and fatal hemopericardium

We report a rare case of cardiac tamponade caused by hemopericardium secondary to erosion and rupture of a coronary artery by an adjacent solitary myocardial abscess. The resulting tamponade led to the sudden death of this 46-year-old man. Antemortem blood culture and the postmortem microscopic examination of the myocardial abscess revealed the causative agent to be Staphylococcus aureus. Hemopericardium due to ventricular wall rupture secondary to a myocardial abscess has been infrequently reported, but, to our knowledge, only one other report of hemopericardium due to coronary artery rupture related to myocardial abscess has been published.

Depressed neutrophil superoxide production in human immunodeficiency virus infection

Neutrophil (PMNL) superoxide (O2-) production was evaluated in 71 patients with human immunodeficiency virus (HIV) infection at different stages of disease. In vitro O2- production was significantly depressed for PMNL isolated from HIV-positive patients compared with control PMNL at rest and after stimulation. The degree of impairment of O2- production was more pronounced for patients with lower absolute CD4+ lymphocyte counts. Antiretroviral therapy with zidovudine was also associated with impaired O2- production, but this may reflect a longer duration of disease for treated patients. Zidovudine had no direct inhibitory effect on O2- production by control PMNL in vitro, and serial measurements of O2- production by PMNL from patients before and after initiation of zidovudine did not demonstrate an in vivo inhibitory effect. Impaired PMNL oxidative metabolism in HIV infection may contribute to the increased risk of serious bacterial infections, certain opportunistic infections, and perhaps the pathogenesis of HIV infection itself.

Human platelet antigen-1 (Zw) typing using PCR-RFLP

The agreement between human platelet antigen-1 typing with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and typing with a serological ELISA method was evaluated. A total of 82 individuals were typed and an absolute correlation was found between the two typing methods. The PCR-RFLP typing method could be clinically useful in a number of immunologically mediated platelet disorders, characterized by severe thrombocytopenia and in early prenatal diagnosis of neonatal alloimmune thrombocytopenia, in which serological methods are difficult to apply because of their dependency on access to platelets and access to well-characterized anti-HPA-1b antisera.

Kinetics of CD11b expression on neutrophils isolated from subjects with healthy gingivae and patients with advanced periodontitis

The adhesion molecule, CD11b/CD18, plays a role in host defense against bacterial infections owing to its involvement in cell migration and phagocytosis. We examined the kinetics of CD11b expression on neutrophils isolated from peripheral blood (PB-PMNs) and gingival crevicular fluid (CF-PMNs) in subjects with healthy gingivae and in patients with advanced periodontitis in order to assess if CF-PMNs respond differently in regard to CD11b expression from PB-PMNs isolated from healthy or periodontitis subjects. CF-PMNs or formylmethionylleucylphenylalanine (fMLP)-stimulated PB-PMNs were incubated in buffer with or without divalent cations for 60, 90, or 110 minutes. Plasma membrane (surface) CD11b as measured by flow cytometry was found to be reduced with time when cells (PB-PMNs or CF-PMNs) from either controls or patients were treated with calcium- and magnesium-free buffer. However, when CF-PMNs were treated with buffer containing Ca++/Mg++, surface CD11b expression increased on cells from both controls and patients. The reduction in CD11b expression on PB-PMNs is significantly greater than that measured on CF-PMNs over time. Therefore, CF-PMNs respond differently from PB-PMNs which have been artificially stimulated with fMLP in regard to kinetics of CD11b expression on the plasma membrane.

Benzodiazepines inhibit neutrophil chemotaxis and superoxide production in a stimulus dependent manner; PK-11195 antagonizes these effects

Diazepam, which binds both central (neuronal) and peripheral (non-neuronal) benzodiazepine binding sites, and Ro5-4864, a ligand selective for benzodiazepine peripheral binding sites (PBS), both inhibited the FMLP induced chemotaxis in human neutrophils at concentrations as low as 10(-8) M. A selective peripheral benzodiazepine antagonist, PK-11195 (10(-5) M), partially reversed the benzodiazepine inhibition of chemotaxis. Diazepam also inhibited the superoxide production induced by FMLP, NaF, and A23187, but not that induced by PMA whose stimulant action was insensitive even to 10(-4) M diazepam. The FMLP-induced superoxide production was most sensitive to diazepam inhibition (ID50 = 2.25 x 10(-6) M diazepam); the effect of NaF was slightly less sensitive (ID50 = 1.34 x 10(-5) M diazepam); and the effect of A23187 was least sensitive as it was suppressed only at 10(-4) M diazepam concentrations. Like diazepam, Ro5-4864 inhibited the FMLP-induced superoxide production, and PK-11195 (10(-5) M) significantly antagonized both diazepam and Ro5-4864 inhibition. Binding studies showed the presence of a saturable benzodiazepine 'peripheral' type binding site (PBS) on human neutrophils with a Kd of 1.2 +/- 0.06 x 10(-8) M (+/- SEM), and a Bmax of 1028 +/- 86.2 fmol/10(6) cells (+/- SEM) for [3H]Ro5-4864; the binding was displaceable by PK-11195, Ro5-4864 and diazepam but not by clonazepam.

Activation of human neutrophils by Mycobacterium tuberculosis-derived sulfolipid-1

The principal sulfatide of a group of acidic lipids from virulent Mycobacterium tuberculosis, sulfolipid-1 (SL-1), stimulates neutrophil superoxide (O2-) generation and, at lower concentrations, primes neutrophil response to several other metabolic agonists including FMLP, and PMA. These responses to SL-1 were examined in relation to diacylglycerol (DAG) generation, Ca2+ availability and activation of guanine nucleotide binding proteins to clarify the signal transduction pathways involved. Pertussis toxin inhibited the ability of SL-1 to both stimulate neutrophils directly and to prime neutrophils for subsequent responses induced by PMA, suggesting a role for one or more guanine nucleotide regulating proteins in both responses. SL-1 induced a rise in neutrophil DAG levels. DAG generation was inhibited by pretreatment of cells with pertussis toxin. Depletion of extracellular Ca2+ ablated O2- release induced by stimulatory levels of SL-1 but did not inhibit the priming effect induced by substimulatory concentrations of the lipid. Investigation of the activation of the neutrophil NADPH oxidase in a cell-free system revealed that the SL-1-priming effect was associated with translocation of the soluble cytosolic factors required for activation of the enzyme. Cytosolic factor translocation was not observed in pertussis toxin pretreated cells. Our results provide evidence for the role of a guanine nucleotide binding protein in both priming and direct activation of neutrophils by SL-1. This G protein regulates both SL-1-induced DAG generation and cytosolic cofactor translocation involved in neutrophil activation and priming. The multiplicity of effects of SL-1 on signal transduction pathways leading to phagocyte activation and priming may exert a profound influence on the pathogenicity of M. tuberculosis.

Activation of human neutrophils by Mycobacterium tuberculosis-derived sulfolipid-1

The principal sulfatide of a group of acidic lipids from virulent Mycobacterium tuberculosis, sulfolipid-1 (SL-1), stimulates neutrophil superoxide (O2-) generation and, at lower concentrations, primes neutrophil response to several other metabolic agonists including FMLP, and PMA. These responses to SL-1 were examined in relation to diacylglycerol (DAG) generation, Ca2+ availability and activation of guanine nucleotide binding proteins to clarify the signal transduction pathways involved. Pertussis toxin inhibited the ability of SL-1 to both stimulate neutrophils directly and to prime neutrophils for subsequent responses induced by PMA, suggesting a role for one or more guanine nucleotide regulating proteins in both responses. SL-1 induced a rise in neutrophil DAG levels. DAG generation was inhibited by pretreatment of cells with pertussis toxin. Depletion of extracellular Ca2+ ablated O2- release induced by stimulatory levels of SL-1 but did not inhibit the priming effect induced by substimulatory concentrations of the lipid. Investigation of the activation of the neutrophil NADPH oxidase in a cell-free system revealed that the SL-1-priming effect was associated with translocation of the soluble cytosolic factors required for activation of the enzyme. Cytosolic factor translocation was not observed in pertussis toxin pretreated cells. Our results provide evidence for the role of a guanine nucleotide binding protein in both priming and direct activation of neutrophils by SL-1. This G protein regulates both SL-1-induced DAG generation and cytosolic cofactor translocation involved in neutrophil activation and priming. The multiplicity of effects of SL-1 on signal transduction pathways leading to phagocyte activation and priming may exert a profound influence on the pathogenicity of M. tuberculosis.

Effect of glucocorticoids and interferon-gamma on the oxidative responses of monocytes from leprosy patients and normal donors

Leprosy patients suffering from erythema nodosum leprosum are frequently treated with glucocorticosteroids. The role glucocorticosteroids and interferon-gamma (IFN-gamma) play in regulating the interaction of phagocytic cells with Mycobacterium leprae was examined. Monocytes from leprosy patients receiving prednisone therapy responded to lower concentrations of IFN-gamma in vitro with enhanced superoxide anion release when challenged with M. leprae or M. bovis BCG than did monocytes from healthy subjects and other leprosy patients. Although the number of patients was small and the population heterogeneous, the data suggested that prednisone could alter IFN-gamma efficacy and led to the examination of the effect of glucocorticosteroids on IFN-gamma activation of monocytes. IFN-gamma treatment following in vitro dexamethasone pretreatment of monocytes from healthy subjects resulted in a greater enhancement of superoxide anion generation than that observed with IFN-gamma treatment alone. These findings are important considerations in evaluating patient immune function because IFN-gamma is being used in a number of clinical trials with leprosy patients.

CD11b expression on neutrophils in human crevicular fluid collected from clinically healthy gingivae

This study investigated the cell surface expression of CD11b (Mo 1, Mac-1, CR 3) by neutrophils (PMNs) from human crevicular fluid (CF-PMNs). CD11b expression on CF-PMNs was compared, using flow cytometry, to that on peripheral blood PMNs (PB-PMNs) isolated simultaneously from the same subjects. CD11b expression by CF-PMNs was also compared to that on PB-PMNs stimulated with formylmethionylleucylphenylalanine (fMLP) or crevicular fluid supernatant (cell-free portion of CF diluted with buffer) (CFS). Crevicular PMNs consistently expressed more CD11b than unstimulated PB-PMNs (p less than 0.001). The level of CD11b expressed on these CF-PMNs was significantly greater than that expressed by PB-PMNs stimulated with 10(-8) M fMLP (p less than 0.05). The level of CD11b surface expression on CF-PMNs was not statistically different from that expressed on PB-PMNs stimulated with CFS or 10(-6) M fMLP. However, CFS significantly stimulated upregulation of surface CD11b expression on PB-PMNs relative to that achieved with 10(-8) M fMLP (0.01 less than p less than or equal to 0.025). Thus it is concluded that CF-PMNs express a high level of CD11b and CFS can upregulate CD11b expression on PB-PMNs to a level that is at least as great as that achieved with 10(-8) M fMLP.

Analysis of neutrophil chemotaxis and CD11b expression in pre-pubertal periodontitis

The objectives of this study were to (1) determine chemotaxis (CX) response by neutrophils (PMNs) isolated from patients with the localized form of pre-pubertal periodontitis (L-PP) and compare these responses with those of age-matched and adult controls, (2) determine the level and up-regulation of CD11b expression upon stimulation with fMLP by peripheral blood PMNs (PB-PMNs) isolated from patients with L-PP and compare these levels with those of age-matched and adult controls, and (3) determine whether there is a correlation between CX and CD11b expression (up-regulation) by PB-PMNs. PB-PMNs from a total of seven patients with L-PP, seven age-matched pediatric controls, and 11 adult controls (four adults for both CD11b and CX assays, and seven adults for CX assays only) were analyzed for CX and CD11b expression. Direct immunofluorescence staining of CD11b was performed with FITC-conjugated monoclonal antibody. Flow cytometry was used to analyze stained cells for their fluorescence intensity. Chemotaxis activity in response to 10(-8) mol/L fMLP was examined in micro-well chemotaxis chambers. The results indicated that CX of PMNs from both L-PP patients and pediatric control subjects was significantly decreased, compared with that of normal adult control subjects (p less than 0.001). There was no significant difference between CX of PMNs from L-PP patients and that from normal pediatric controls (p greater than 0.7). CD11b expression did not significantly differ among L-PP patients, normal pediatric controls, and adult controls.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of monocyte oxidative responses in leprosy patients and healthy subjects as influenced by mycobacterial lipid pretreatment

Superoxide anion (O2-) release by monocytes from leprosy patients in a paired study was lower than that released by monocytes from healthy controls. Pretreatment of healthy control monocytes with phenolic glycolipid-I (PGL-I) of Mycobacterium leprae resulted in the release of less O2- than released by buffer-treated cells or cells pretreated with structurally similar lipids. However, pretreatment of patient monocytes with PGL-I did not affect the O2- generation, perhaps because the cells already had a lower capacity to produce O2-. Upon further examination of the data from the patient population, monocytes from lepromatous patients released significantly less O2- than cells from normal controls, while tuberculoid patient cells released O2- in amounts similar to that generated by cells from normal controls. In addition, monocytes from patients with a high bacterial index had a lower capacity to generate O2- when compared to cells from healthy individuals.

Killing of Mycobacterium tuberculosis by neutrophils: a nonoxidative process

To determine the role of oxygen radicals in the killing of Mycobacterium tuberculosis by neutrophils, the effects of free-radical inhibitors and enzymes, catalase, superoxide dismutase, taurine, deferoxamine, and histidine were evaluated. Changes in the viability of M. tuberculosis were determined by agar plate colony counts and a radiometric assay. No impairment in killing was seen with any of the inhibitors or enzymes. Patients with chronic granulomatous disease (CGD) have a defect in the NADPH oxidase pathway, causing their neutrophils to be unable to generate oxygen radicals. If these radicals are involved in killing, then CGD neutrophils should be less effective killers of M. tuberculosis than normal neutrophils. There was no evidence by either measure of M. tuberculosis viability that CGD neutrophils were less bactericidal than normal neutrophils. Killing by normal neutrophils was also effective in the absence of serum. These results lead to the conclusion that the mechanism by which M. tuberculosis is killed by neutrophils is independent of the oxygen metabolic burst.

Suppression of monocyte oxidative response by phenolic glycolipid I of Mycobacterium leprae

Mycobacterium leprae synthesizes a unique phenolic glycolipid (PGL-I) in abundant quantities. We studied the effect of PGL-I on the generation of superoxide anion (O2-) by stimulated human monocytes. Peripheral blood monocytes pretreated with PGL-I released less O2- when stimulated with M. leprae than did control monocytes. Monocytes pretreated with dimycocerosyl phthiocerol, mycoside A of Mycobacterium kansasii, or mycoside B of Mycobacterium microti, on the other hand, released O2- in quantities comparable to control monocytes in response to M. leprae stimulation. Monocyte O2- release in response to other stimuli of the oxidative metabolic burst, such as PMA, zymosan, Mycobacterium bovis Bacille Calmette-Guérin, or M. kansasii, was unaffected by lipid pretreatment. These findings demonstrate that PGL-I has a direct effect on monocyte O2- generation in response to M. leprae and suggest that PGL-I is a modulator of phagocytic cell function.

Suppression of monocyte oxidative response by phenolic glycolipid I of Mycobacterium leprae

Mycobacterium leprae synthesizes a unique phenolic glycolipid (PGL-I) in abundant quantities. We studied the effect of PGL-I on the generation of superoxide anion (O2-) by stimulated human monocytes. Peripheral blood monocytes pretreated with PGL-I released less O2- when stimulated with M. leprae than did control monocytes. Monocytes pretreated with dimycocerosyl phthiocerol, mycoside A of Mycobacterium kansasii, or mycoside B of Mycobacterium microti, on the other hand, released O2- in quantities comparable to control monocytes in response to M. leprae stimulation. Monocyte O2- release in response to other stimuli of the oxidative metabolic burst, such as PMA, zymosan, Mycobacterium bovis Bacille Calmette-Guérin, or M. kansasii, was unaffected by lipid pretreatment. These findings demonstrate that PGL-I has a direct effect on monocyte O2- generation in response to M. leprae and suggest that PGL-I is a modulator of phagocytic cell function.

Effect of Mycobacterium tuberculosis-derived sulfolipid I on human phagocytic cells

Experiments were performed to determine the effects of Mycobacterium tuberculosis-derived sulfolipid I on phagocytic cells. Sulfolipid I was taken up in significant amounts by human neutrophils and in lesser amounts by monocytes and lymphocytes. Superoxide (O2-) production by neutrophils was significantly increased by sulfolipid I, but the rate of production was slower than that reported previously for other stimuli. The optimal concentration of sulfolipid I for stimulation of O2- production was 27 micrograms/ml, while higher concentrations produced less. At substimulatory levels sulfolipid I caused enhancement of O2- release from neutrophils when it was subsequently stimulated by other agents. Nonadherent monocytes from most normal donors failed to produce O2- when treated with sulfolipid I; however, adherent monocytes pretreated with gamma interferon did produce O2- with sulfolipid I stimulation. Priming for an enhanced oxidative response of activated monocytes was also observed. These sulfolipid I-induced changes in phagocytic cell function may be important in altering the ability of phagocytes to respond effectively to M. tuberculosis and may also cause exaggerated inflammatory responses.

Human phagocytic cell responses to Mycobacterium leprae and Mycobacterium bovis Bacillus Calmette-Guérin. An in vitro comparison of leprosy vaccine components

Components of current vaccines for Hansen's disease include Mycobacterium bovis Bacillus Calmette-Guérin (BCG) and killed Mycobacterium leprae. BCG infections in humans are rare and most often occur in immune-compromised individuals. M. leprae on the other hand, although not causing clinical disease in most exposed individuals, is capable of infecting and replicating within mononuclear phagocytes. Lymphocytes from patients with the lepromatous form of Hansen's disease exhibit defective lymphokine production when challenged in vitro with M. leprae. This may result in inefficient mononuclear phagocyte activation for oxidative killing. To study the ability of normal phagocytes to ingest and respond oxidatively to BCG and M. leprae, we measured phagocytic cell O2- release and fluorescent oxidative product formation and visually confirmed the ingestion of the organisms. BCG stimulated a vigorous O2- generation in neutrophils and monocytes and flow cytometric oxidative product generation by neutrophils occurred in the majority of cells. M. leprae, stimulated a weak but significant O2- release requiring a high concentration of organisms and long exposure. By flow cytometric analysis, most neutrophils were able to respond to both organisms with the generation of fluorescent oxidative products. Neutrophil oxidative responses to M. leprae were substantially less than responses seen from neutrophils exposed to BCG. By microscopic examination of neutrophils phagocytizing FITC-labeled bacteria, it was shown that both M. leprae and BCG were slowly ingested but that more BCG appeared to be associated with the cell membrane of more of the cells. When phagocytic cells were incubated with BCG and M. leprae for 30 min and subsequently examined by electron microscopy, few organisms were seen in either neutrophils or monocytes. This suggests that BCG are easily recognized and slowly ingested by normal phagocytic cells, the majority of which respond with a strong oxidative burst. M. leprae appeared to only weakly stimulate phagocyte oxidative responses and were also slowly phagocytized.

Human phagocytic cell responses to Mycobacterium leprae and Mycobacterium bovis Bacillus Calmette-Guérin. An in vitro comparison of leprosy vaccine components

Components of current vaccines for Hansen's disease include Mycobacterium bovis Bacillus Calmette-Guérin (BCG) and killed Mycobacterium leprae. BCG infections in humans are rare and most often occur in immune-compromised individuals. M. leprae on the other hand, although not causing clinical disease in most exposed individuals, is capable of infecting and replicating within mononuclear phagocytes. Lymphocytes from patients with the lepromatous form of Hansen's disease exhibit defective lymphokine production when challenged in vitro with M. leprae. This may result in inefficient mononuclear phagocyte activation for oxidative killing. To study the ability of normal phagocytes to ingest and respond oxidatively to BCG and M. leprae, we measured phagocytic cell O2- release and fluorescent oxidative product formation and visually confirmed the ingestion of the organisms. BCG stimulated a vigorous O2- generation in neutrophils and monocytes and flow cytometric oxidative product generation by neutrophils occurred in the majority of cells. M. leprae, stimulated a weak but significant O2- release requiring a high concentration of organisms and long exposure. By flow cytometric analysis, most neutrophils were able to respond to both organisms with the generation of fluorescent oxidative products. Neutrophil oxidative responses to M. leprae were substantially less than responses seen from neutrophils exposed to BCG. By microscopic examination of neutrophils phagocytizing FITC-labeled bacteria, it was shown that both M. leprae and BCG were slowly ingested but that more BCG appeared to be associated with the cell membrane of more of the cells. When phagocytic cells were incubated with BCG and M. leprae for 30 min and subsequently examined by electron microscopy, few organisms were seen in either neutrophils or monocytes. This suggests that BCG are easily recognized and slowly ingested by normal phagocytic cells, the majority of which respond with a strong oxidative burst. M. leprae appeared to only weakly stimulate phagocyte oxidative responses and were also slowly phagocytized.

Rapid visualization of Acanthamoeba using fluorescein-conjugated lectins

We investigated the efficacy of fluorescein-conjugated lectins (FCLs) for the rapid visualization of Acanthamoeba species. Cultures of Acanthamoeba castellani, Acanthamoeba culbertsoni, and Acanthamoeba polyphaga were established on nonnutrient agar plates supplemented with Escherichia coli. Maximal trophozoite populations were established four to five days after initial subculturing; mature cysts were routinely noted three to six days later. At various time points, trophozoites and/or cysts were harvested and suspended in Page's saline. Following a previously described protocol, samples of the suspensions were placed on glass slides and incubated with one of a panel of 14 FCLs. At the end of the incubation period, the slides were examined using an epifluorescence microscope. Concanavalin A brightly stained both cysts and trophozoites. Wheat germ agglutinin brightly stained cysts but only minimally stained trophozoites. These results suggest that FCLs may be useful for rapid visualization of Acanthamoeba organisms in corneal infections.

Rhinitis, pneumonia, and defective neutrophil function in the Doberman pinscher

Eight closely related Doberman Pinschers with chronic rhinitis and pneumonia had normal or increased numbers of structurally normal leukocytes. Serum concentrations of immunoglobulins and complement were above or within normal ranges. Lymphocyte transformation indices for 3 mitogens were normal in 7 of the 8 dogs; the remaining dog had low values for all mitogens. Neutrophils phagocytized bacteria normally, but had impaired bactericidal ability. The bactericidal defect may have been related to the inability of neutrophils to generate normal numbers of oxygen radicals after stimulation, as determined by decreased ability of neutrophils to reduce nitroblue tetrazolium and to produce superoxide following opsonized zymosan stimulation. These observations, plus finding chronic inflammatory disease in the lungs of one dog, indicated that the disease may have some similarity to chronic granulomatous disease or to complement receptor deficiency in man.