Ibuprofen for the prevention of patent ductus arteriosus in preterm and/or low birth weight infants

BACKGROUND

A patent ductus arteriosus (PDA) often complicates the clinical course of preterm infants and increases the risk of intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), chronic lung disease (CLD) and death. The standard treatment to close a PDA is indomethacin. Its use is associated with renal, gastrointestinal and cerebral side-effects. Ibuprofen has been shown to be effective in closing a PDA without reducing blood flow velocity to the brain, gut or kidneys.

OBJECTIVES

To determine the effectiveness and safety of prophylactic ibuprofen compared to placebo/no intervention or other cyclo-oxygenase inhibitor drugs (indomethacin, mefenamic acid, etc) in the prevention of PDA in preterm infants.

SEARCH STRATEGY

Randomized controlled trials comparing prophylactic ibuprofen use with placebo/no intervention/indomethacin were identified by searching the Cochrane Controlled Trial Register (The Cochrane Library, Issue 4, 2002), MEDLINE (1966-November 2002), CINAHL (1982-November 2002), EMBASE (1980-November 2002), reference lists of published trials and abstracts published in Pediatric Research (1990-2002). No language restrictions were applied.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials comparing use of ibuprofen with placebo/no intervention or other cyclo-oxygenase inhibitor drugs (indomethacin, mefenamic acid, etc) for the prevention of PDA in preterm and/or low birth weight infants.

DATA COLLECTION AND ANALYSIS

Data regarding the clinical outcomes including presence of PDA on day three and day seven, need for surgical ligation, need for rescue treatment with cyclo-oxygenase inhibitors, IVH, mortality, renal and gastrointestinal complications were extracted. Meta-analyses were performed using RevMan 4.1 and treatment estimates were reported as weighted mean difference (WMD), typical relative risk (RR), typical risk difference (RD) and, if statistically significant, number needed to treat (NNT) or number needed to harm (NNH), along with their 95% confidence intervals (CI).

MAIN RESULTS

Four trials (n = 623) were included in the review. There was a statistically significant decrease in the incidence of PDA on day three in the ibuprofen group [typical RR 0.36 (95% CI 0.26, 0.49); typical RD -0.29 (95% CI -0.37, -0.21); NNT 3 (95% CI 3, 5); 3 trials, n = 488]. There was a significant increase in the serum creatinine levels in the ibuprofen group [WMD 0.11 mg/dl (95% CI 0.06, 0.17); 2 trials, n = 438]. There were no statistically significant differences in mortality, grade 3 or 4 IVH, CLD at 28 days or 36 weeks, need for surgical closure of PDA, NEC, GI hemorrhage, time to reach full feeds and urine output. One trial (Gournay 2002) (n = 135) reported on three infants in the ibuprofen group who developed pulmonary hypertension responsive to nitric oxide treatment.

REVIEWER'S CONCLUSIONS

Prophylactic use of ibuprofen reduces the incidence of PDA. However, further trials, which address potential adverse effects including pulmonary hypertension, are needed. Such trials should include long-term neurodevelopmental outcomes. Trials comparing the effectiveness of prophylactic use of indomethacin versus ibuprofen may be warranted with particular reference to IVH, need for surgical ligation and neurodevelopmental outcome.

Inhaled versus systemic corticosteroids for preventing chronic lung disease in ventilated very low birth weight preterm neonates

BACKGROUND

Chronic lung disease (CLD) remains an important cause of mortality and morbidity in preterm infants despite the administration of antenatal corticosteroids, surfactant replacement therapy and other advances in neonatal intensive care. There is increasing evidence from cellular and biochemical research that inflammation plays an important role in the pathogenesis of CLD. Thus, interventions aimed at reducing or modulating the inflammatory process may reduce the incidence or severity of CLD. Theoretically, the use of inhaled corticosteroids may allow for beneficial effects on the pulmonary system without concomitant high systemic concentrations and less risk of adverse effects.

OBJECTIVES

To compare the effectiveness of inhaled versus systemic corticosteroids, started within the first two weeks of life, in preventing CLD in ventilated very low birth weight infants.

SEARCH STRATEGY

Randomized and quasi-randomized trials were identified by searching the Cochrane Controlled Trials Register (The Cochrane Library, Issue 3, 2002), MEDLINE (1966 - September 2002), EMBASE (1980 - September 2002), CINAHL (1982 - September 2002), reference lists of published trials and abstracts published in Pediatric Research (1990 - April 2002) from the Society of Pediatric Research/ Pediatric Academic Society's annual meetings.

SELECTION CRITERIA

Randomized or quasi-randomized clinical trials comparing inhaled versus systemic corticosteroid therapy (regardless of the dose and duration of therapy), started in first two weeks of life in very low birth weight preterm infants receiving assisted ventilation.

DATA COLLECTION AND ANALYSIS

Data regarding clinical outcomes including CLD at 28 days or 36 weeks corrected gestational age (CGA), mortality, combined outcome of death or CLD at 28 days or 36 weeks CGA, other pulmonary outcomes and adverse effects were evaluated. All data were analyzed using RevMan 4.1. When appropriate, meta-analysis was performed using relative risk (RR), risk difference (RD), and weighted mean difference (WMD) along with their 95% confidence intervals (CI). If RD was significant, number needed to treat (NNT) or number needed to harm (NNH) was calculated.

MAIN RESULTS

Two trials qualified for inclusion in this review. There was an increase in the incidence of CLD at 36 weeks CGA in the inhaled steroid group amongst all randomized infants, which was of borderline statistical significance: [RR 1.45 (95% CI 0.99, 2.11); RD 0.11 (95% CI 0.00, 0.21), p = 0.05, 1 trial and n = 278]. There was no statistically significant difference in the incidence of CLD at 36 weeks amongst all survivors [RR 1.34 (95% CI 0.94, 1.90); RD 0.11(95% CI -0.02, 0.24), 1 trial and n = 206]. There were no statistically significant differences for oxygen dependency at 28 days (2 trials and n = 294), death by 28 days (2 trials and n = 294) or 36 weeks (2 trials and n = 294) and the combined outcome of death or CLD by 28 days (2 trials and n = 294) or 36 weeks CGA (1 trial and n = 278). The duration of mechanical ventilation was statistically significantly longer in the inhaled as compared to the systemic steroid group (WMD 3.89 days, 95% CI 0.24, 7.55; 2 trials and n = 294). The duration of supplemental oxygen was statistically significantly longer in the inhaled as compared to the systemic steroid group (WMD 11.10 days, 95% CI 1.97, 20.22; 2 trials and n = 294). There was a significantly lower incidence of hyperglycemia in the group receiving inhaled steroids (RR 0.52, 95% CI 0.39,0.71; RD -0.25, 95% CI -0.37, -0.14; 1 trial and n = 278). The NNT was 4.0 (95% CI 2.7, 7.14) to avoid one infant experiencing hyperglycemia. There was a statistically significant increase in the rate of patent ductus arteriosus (RR 1.64, 95% CI 1.23, 2.17; RD 0.21, 95% CI 0.10, 0.33; 1 trial and n = 278) in the group receiving inhaled steroids. The NNH was 4.8, 95% CI 3, 10. There were decreases of borderline statistical significance in the incidences of gastrointestinal hemorrhage and gastrointestinal perforation in the inhaled as compared to systemic steroid group: for gastrointestinal hemorrhage, RR 0.40, 95% CI 0.16, 1.02; RD -0.06, 95% CI -0.12, 0.00, p = 0.05 (1 trial and n = 278); for gastrointestinal perforation, RR 0.16, 95% CI 0.02, 1.29; RD -0.04, 95% CI -0.07, 0.00, p = 0.05 (1 trial and n = 278). The incidence of other side effects was not statistically significantly different in the two groups. No information was available on long term neurodevelopmental outcomes.

REVIEWER'S CONCLUSIONS

This review found no evidence that early inhaled steroids confer important advantages over systemic steroids in the management of ventilator dependent preterm infants. Neither inhaled steroids, nor systemic steroids, can be recommended as a part of standard practice for ventilated preterm infants. Because they might have fewer adverse effects than systemic steroids, further randomized controlled trials of inhaled steroids are needed which address risk/benefit ratio of different delivery techniques, dosing schedules and long term effects, with particular attention to neurodevelopmental outcome.

Inhaled versus systemic corticosteroids for the treatment of chronic lung disease in ventilated very low birth weight preterm infants

BACKGROUND

Chronic lung disease (CLD) remains a serious and common problem among very low birth weight infants despite the use of antenatal steroids and postnatal surfactant therapy to decrease the incidence and severity of respiratory distress syndrome. Corticosteroids have been widely used to treat or prevent CLD due to their anti-inflammatory properties. However, the use of systemic steroids has been associated with serious short and long term adverse effects. Administration of corticosteroids topically through the respiratory tract might result in beneficial effects on the pulmonary system with fewer undesirable systemic side effects.

OBJECTIVES

To compare the effectiveness of inhaled versus systemic corticosteroids administered to ventilator dependent preterm neonates with birth weight </= 1500 grams or gestational age </= 32 weeks after two weeks of life for the treatment of evolving CLD.

SEARCH STRATEGY

Randomized and quasi-randomized trials were identified by searching the Cochrane Controlled Trials Register (The Cochrane Library, Issue 3, 2002), MEDLINE (1966 - September 2002), EMBASE (1980 - September 2002), CINAHL (1982 - September 2002), reference lists of published trials and abstracts published in Pediatric Research (1990 - April 2002) from the Society for Pediatric Research/Pediatric Academic Societies' Annual Meetings.

SELECTION CRITERIA

Randomized or quasi-randomized trials comparing inhaled versus systemic corticosteroid therapy (irrespective of the dose and duration of therapy) starting after the first two weeks of life in ventilator dependent very low birth weight preterm neonates.

DATA COLLECTION AND ANALYSIS

Data were extracted regarding clinical outcomes including CLD at 28 days or 36 weeks corrected gestational age (CGA), mortality, combined outcome of death or CLD at 28 days or 36 weeks CGA, other pulmonary outcomes and adverse effects. All data were analyzed using RevMan 4.1. When appropriate, meta-analysis was performed using relative risk (RR), risk difference (RD), and weighted mean difference (WMD) along with their 95% confidence intervals (CI). If RD was statistically significant, number needed to treat (NNT) was calculated.

MAIN RESULTS

Five trials comparing inhaled versus systemic corticosteroids in the treatment of CLD were identified. Two trials were excluded as both included non ventilator dependent patients. One trial is awaiting assessment and clarification of published data. Two trials qualified for inclusion in this review. Halliday et al (Halliday 2001a) randomized infants < 72 hours, while Suchomski et al (Suchomski 2002) randomized at 12-21 days. Although the steroids were commenced after the first 2 weeks of life in both the trials, the outcomes were measured over different time periods, from the age at randomization in each trial, making it inappropriate to combine results. In neither trial was there a statistically significant difference between the groups in the incidence of CLD at 36 weeks CGA amongst all randomized infants. The estimates for the trial by Halliday et al (Halliday 2001a) were RR 1.10 (95% CI 0.82, 1.47), RD 0.03 (95% CI -0.08, 0.15); number of infants (n) = 292 and for the trial by Suchomski et al (Suchomski 2002) RR 0.90 (95% CI 0.79, 1.02), RD -0.10 (95% CI -0.22, 0.02; n = 78 ). There were no statistically significant differences between the groups in either trial for oxygen dependency at 28 days, death by 28 days or 36 weeks, the combined outcome of death or CLD by 28 days or 36 weeks CGA, duration of intubation, duration of oxygen dependence, or adverse effects. Information on the long term neurodevelopmental outcomes was not available.

REVIEWER'S CONCLUSIONS

This review found no evidence that inhaled corticosteroids confer net advantages over systemic corticosteroids in the management of ventilator dependent preterm infants. Neither inhaled steroids, nor systemic steroids, can be recommended as standard treatment for ventilated preterm infants. There was no evidence of difference in effectiveness or side-effect profiles for inhaled versus systemic steroids. A better delivery system guaranteeing selective delivery of inhaled steroids to the alveoli might result in beneficial clinical effects without increasing side-effects. To resolve this issue, studies are needed to identify the risk/benefit ratio of different delivery techniques and dosing schedules for the administration of these medications. The long term effects of inhaled steroids, with particular attention to neurodevelopmental outcome, should be addressed in future studies.

Disseminated aspergillosis inciting intestinal ischaemia and obstruction

Invasive aspergillosis is an opportunistic infection that characteristically affects the immunocompromised host, resulting in a high degree of morbidity and mortality. Although the portal of entry is usually pulmonary, there are rare reports of invasive aspergillosis localized to the gastrointestinal tract. In addition, haematological spread may develop, with life threatening disseminated infection involving the vital organs and the gastrointestinal tract. Although disseminated infection is well recognized, the CT findings of gastrointestinal disease have not been reported to our knowledge. We describe the CT findings in a patient with invasive aspergillosis involving the gastrointestinal tract, which resulted in intestinal ischaemia complicated by small bowel obstruction.

Retropharyngeal aberrant thymus

INTRODUCTION

Upper airway obstruction from a retropharyngeal mass requires urgent evaluation. In children, the differential diagnosis includes infection, trauma, neoplasm, and congenital abnormalities. Aberrant cervical thymic tissue, although occasionally observed on autopsy examination, is rarely clinically significant. We present the case of an infant with respiratory distress attributed to aberrant thymic tissue located in the retropharyngeal space.

CASE

A 6-week-old infant was brought to the emergency department for evaluation of stridor associated with periodic episodes of cyanosis. Lateral neck radiograph revealed widening of the retropharyngeal soft tissues. The patient's symptoms did not improve with intravenous ampicillin-sulbactam. Magnetic resonance imaging (MRI) performed on the seventh day of hospitalization revealed a retropharyngeal mass that extended to the carotid space. The mass was easily resected using an intraoral approach. Microscopic examination demonstrated thymic tissue. A normal thymus was also observed in the anterior mediastinum on MRI. The patient recovered uneventfully and had no further episodes of stridor or cyanosis.

DISCUSSION

Aberrant cervical thymic tissue may be cystic or solid. Cystic cervical thymus is more common, and 6% of these patients present with symptoms of dyspnea or dysphagia. Aberrant solid cervical thymus usually presents as an asymptomatic anterior neck mass. This case is unusual in that solid thymic tissue was located in the retropharynx, a finding not previously reported in the English literature. Additionally, the patient presented in acute respiratory distress, and the diagnosis was confounded by the presence of mild laryngomalacia. In retrospect, our patient likely had symptoms of intermittent upper airway obstruction since birth. The acute respiratory distress at presentation was likely the result of laryngomalacia exacerbated by the presence of aberrant thymic tissue and a superimposed viral infection. Aberrantly located thymic tissue arises as a consequence of migrational defects during thymic embryogenesis. The thymus is a paired organ derived from the third and, to a lesser extent, fourth pharyngeal pouches. After its appearance during the sixth week of fetal life, it descends to a final position in the anterior mediastinum, adjacent to the parietal pericardium. Aberrant thymic tissue results when this tissue breaks free from the thymus as it migrates caudally. Therefore, aberrant thymic tissue may be found in any position along a line from the angle of the mandible to the sternal notch, and in the anterior mediastinum to the level of the diaphragm. In an autopsy study of 3236 children, abnormally positioned thymic tissue was found in 34 cases (1%). The aberrant thymus was most often located near the thyroid gland (n = 19 cases) but was also detected lower in the anterior neck (n = 6 cases), higher in the anterior neck (n = 8 cases), and at the left base of the skull (n = 1 case). The presence of thymic tissue in the retropharyngeal space in our patient is more unusual given the typical embryologic origin and descent of the thymus in the anterior neck to the mediastinum. Children with aberrant thymus may have associated anomalies. Twenty-four of 34 children (71%) with aberrant thymus detected at autopsy had features consistent with DiGeorge syndrome, and only 5 of the remaining 10 patients had a normal mediastinal thymus present. Our patient had normal serum calcium levels after excision and a mediastinal thymus was visualized on MRI. Biospy is required for diagnosis of cervical thymus and should also be considered to exclude other causes. MRI is helpful in delineating the presence, position, and extent of thymic tissue. Immunologic sequelae or recurrence after resection of an aberrant cervical thymus has not been reported.

In vitro sealing of punctured fetal membranes: potential treatment for midtrimester premature rupture of membranes

OBJECTIVE

Midtrimester premature rupture of membranes causes significant perinatal morbidity and death. No effective treatment exists. We investigated (1) whether a needle puncture in the fetal membranes could be sealed in vitro and (2) the optimal composition of the sealant to be used.

STUDY DESIGN

Membranes from second trimester pregnancies (16-24 weeks of gestation) were stretched over a modified syringe with a 2.5-cm open diameter. The syringe was filled with 20 mL of second trimester amniotic fluid, and the membrane was punctured with a 20-gauge needle. Sealants were injected into the amniotic fluid. The primary outcome variable was time for leakage of amniotic fluid. Median times for leakage for the formulations were compared by Wilcoxon exact rank sum test.

RESULTS

Platelets alone failed to seal the puncture site. All other formulations stopped leakage temporarily. Tisseel (Baxter Corp, Glendale, Calif) and cryoprecipitate/thrombin preparations led to more prolonged sealing of punctured amniotic membranes than platelets (P <.01) and were not significantly different from each other.

CONCLUSION

Of the sealants tested in vitro, amniotic membranes are best sealed by a fibrin/thrombin-based sealant.

Nosocomial outbreak of Microbacterium species bacteremia among cancer patients

To date, only 6 sporadic Microbacterium species (formerly coryneform Centers for Disease Control and Prevention [CDC] groups A-4 and A-5) infections have been reported. The source, mode of transmission, morbidity, mortality, and potential for nosocomial transmission of Microbacterium species remain unknown. From 26 July through 14 August 1997, 8 episodes of coryneform CDC group A-5 symptomatic bacteremia occurred in 6 patients on the oncology ward at the Maine Medical Center. One patient died. All isolates were identified at CDC as Microbacterium species and had identical DNA banding patterns by pulsed-field gel electrophoresis. To assess risk factors for Microbacterium species infection, a retrospective cohort study was conducted. The presence of a central venous catheter was the strongest risk factor (6/6 vs. 22/48; relative risk, 3.2; P<.0001). This outbreak demonstrates significant Microbacterium species-associated morbidity and mortality in immunocompromised populations and confirms the potential for epidemic nosocomial transmission.

Effect of feedback on obstetrics and gynecology residents' teaching performance and attitudes

OBJECTIVE

To evaluate obstetrics and gynecology residents' teaching performance, perception of the importance of teaching and satisfaction with their evaluations after the institution of an oral or written medical student feedback and award system.

STUDY DESIGN

Residents at a single, university-based obstetrics and gynecology program were assigned to receive either oral, written or no medical student feedback on their teaching skills in a prospective, randomized, controlled trial. Students rated resident performance in seven teaching categories. Residents' scores per six-week block were evaluated for one year. Questionnaires addressing resident attitudes toward feedback were collected at baseline and at 6 and 12 months. All residents then received written feedback and public awards for high scores for an additional year.

RESULTS

After 12 months of feedback there were trends toward improvement in several of the teaching categories and overall evaluations. None of the controls, 29% of residents receiving oral feedback and 50% of residents receiving written feedback rated teaching as more important than before. None of the controls, 57% of those receiving oral feedback (P = NS) and 88% of those receiving written feedback (P = .009), for a total of 73% of residents receiving any feedback (P = .001), thought that the amount of feedback was adequate at 12 months. Follow-up of 15 residents after one year of written feedback with an award for high evaluations showed that 60% improved their overall scores. The mean overall group score improved.

CONCLUSION

A feedback and award system can lead to improved resident teaching performance as well as enhanced perception of residents' role as teachers and greater resident satisfaction.

Epidemiology of dyspepsia in the general population in Mumbai

BACKGROUND AND AIMS

Dyspepsia is a common complaint in the general population. The prevalence, demography and economic implications of dyspepsia in India are not known; we studied these using a detailed symptom questionnaire.

METHODS

2549 presumably healthy adults (mean age 37.2 [14.1] years; 1441 men) were interviewed. Gastrointestinal symptoms, their investigation and treatment, dietary history and history of addictions were noted. Dyspepsia was defined as abdominal fullness or upper abdominal pain present for at least one month; irritable bowel syndrome (IBS) was defined by Manning's criteria. Based on the symptom profile, subjects were divided into three broad groups: no dyspepsia (n=1695; 945 men), dyspepsia with (110; 63 men) or without (664; 382 men) IBS, and IBS alone (80; 51 men).

RESULTS

774 subjects (30.4%) had dyspepsia; the median (range) duration of symptoms was 24 (1-360) months. Abdominal fullness (n=614), abdominal pain (374), heartburn (272) and belching (271) were the most common symptoms; significant symptoms (present at least once a week) occurred in 306 subjects (12.0% of the population). More than half the subjects had symptoms suggestive of mixed type of dyspepsia; dysmotility-like dyspepsia was the next most common (n=257; 33.2%). The frequency of dyspepsia was not related to type of diet or consumption of spices. Dyspepsia was more prevalent in subjects who abused tobacco or alcohol. Three hundred and twenty-one subjects with dyspepsia (41.4%) had visited a physician for their complaints and had received treatment with antacids, acid suppressors or prokinetic drugs; 4.5% and 7.2% had undergone previous endoscopy and ultrasonography, respectively; dyspeptic subjects underwent more investigations (p<0.001) than those with IBS.

CONCLUSIONS

Dyspepsia is reported by almost one-third of the population in Mumbai; significant symptoms occur in 12%. Forty percent of these subjects receive treatment and only a small number undergo endoscopy or ultrasonography.

Symptoms of dry eye and recurrent erosion syndrome after refractive surgery

PURPOSE

To determine the incidence and severity of patient complaints typical of dry eye and recurrent erosion syndrome after excimer laser refractive surgery and to compare the incidence of these symptoms after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK).

SETTING

Outpatient university practice.

METHODS

A questionnaire was mailed to 1731 patients who had had primary myopic PRK or LASIK at least 6 months previously. Questions were designed to determine the incidence and character of ocular dryness and recurrent erosion symptoms and their impact on patient satisfaction and willingness to have surgery again. Responses from PRK and LASIK patients were compared.

RESULTS

Responses from 231 PRK patients and 550 LASIK patients revealed an incidence of dryness symptoms in 43% and 48%, respectively (P >.05). Soreness of the eye to touch was reported by 26.8% and 6.7%, respectively (P <.0001). Sharp pains occurred in 20.4% of PRK patients and 8.0% of LASIK patients (P =.0001). Complaints of the eyelid sticking to the eyeball occurred in 14.7% and 5.6%, respectively (P =.0001). All symptoms occurred predominantly on waking. Frequency of eyelid sticking (P <.0005) and sharp pain (P <.005) symptoms, as well as severity of sharp pain symptoms (P <.0001), were significantly greater in PRK patients than in LASIK patients. On a scale of 0 to 10 (10 high), median overall patient satisfaction with surgery was 9 in both groups. Soreness of the eyelid to touch occurred significantly more frequently among patients with symptoms of sharp pains on waking (P <.001) and the sensation of the eyelid sticking to the eyeball (P <.001). Patients with 1 or more symptoms were twice as likely as asymptomatic patients to have a satisfaction score of less than 8 (P <.001).

CONCLUSIONS

Ocular dryness symptoms occurred commonly after PRK and LASIK. Symptoms suggestive of mild recurrent erosions included sharp pains, the sensation of the eyelid sticking to the eyeball, and soreness of the eyelid to touch, a previously unrecognized symptom of this condition. These symptoms occurred commonly after excimer laser procedures but were significantly more common, more severe, and more prolonged after PRK. The presence of these symptoms had a significant effect on patient satisfaction.

Group C streptococcal meningitis: case report and review of the literature

Group C streptococci are a common cause of epidemic bacterial infection in animals. These organisms are a rare but frequently fatal cause of meningitis in humans. We report the case of a 13-year-old girl with meningitis caused by a group C Streptococcus (Streptococcus zooepidemicus) successfully treated with vancomycin and third generation cephalosporins. We also review cases of group C streptococcal meningitis reported previously.

Random circular permutation leading to chain disruption within and near alpha helices in the catalytic chains of aspartate transcarbamoylase: effects on assembly, stability, and function

A collection of circularly permuted catalytic chains of aspartate transcarbamoylase (ATCase) has been generated by random circular permutation of the pyrB gene. From the library of ATCases containing permuted polypeptide chains, we have chosen for further investigation nine ATCase variants whose catalytic chains have termini located within or close to an alpha helix. All of the variants fold and assemble into dodecameric holoenzymes with similar sedimentation coefficients and slightly reduced thermal stabilities. Those variants disrupted within three different helical regions in the wild-type structure show no detectable enzyme activity and no apparent binding of the bisubstrate analog N:-phosphonacetyl-L-aspartate. In contrast, two variants whose termini are just within or adjacent to other alpha helices are catalytically active and allosteric. As expected, helical disruptions are more destabilizing than loop disruptions. Nonetheless, some catalytic chains lacking continuity within helical regions can assemble into stable holoenzymes comprising six catalytic and six regulatory chains. For seven of the variants, continuity within the helices in the catalytic chains is important for enzyme activity but not necessary for proper folding, assembly, and stability of the holoenzyme.

Apolipoprotein deficiency and chronic liver disease

Deficiency of apolipoprotein can be of genetic origin or due to diseases like advanced chronic liver disease. Deficiency of apolipoprotein A causes Tangier disease without any major hepatic involvement being reported. Deficiency of apolipoprotein B causes abetalipoproteinemia or familial hypobetalipoproteinemia; with hepatic involvement in the form of raised transaminases, fatty liver and cirrhosis. Advanced chronic liver disease itself can cause reduction of apolipoprotein A and apolipoprotein B levels and acanthocytosis. In patients with chronic liver disease of undetermined etiology, lipid profile and apolipoprotein levels should be obtained routinely. If it suggests apolipoprotein B deficiency, then liver biopsy can be avoided, as the etiology of chronic liver disease is established. Isolated deficiency of either apolipoprotein A or apolipoprotein B suggests etiology of chronic liver disease, while deficiency of both apolipoprotein A and apolipoprotein B is a manifestation of advanced chronic liver disease.

Interaction of cigarette smoke and house dust mite allergens on inflammatory mediator release from primary cultures of human bronchial epithelial cells

Several studies have shown that exposure to cigarette smoke and/or house dust mite (HDM) can lead to increased airway inflammation in susceptible individuals. The underlying mechanisms, however, are not defined. To investigate the interaction between cigarette smoke and HDM allergen on mediator release from primary cultures of human bronchial epithelial cells. Confluent human bronchial epithelial cell cultures were exposed to cigarette smoke in the absence or presence of HDM allergen and investigated for the release of IL-8, IL-1beta, and sICAM-1. Damage to the epithelial cells themselves was assessed by release of 51Cr. On separate occasions, we investigated the effect of PTL11028, a highly potent and selective Der p1 inhibitor, on HDM allergen-induced release of IL-8, following activation of HDM allergen by incubation with cysteine. The effect of cigarette smoke exposure on the stability of these released mediators in prepared solutions in the absence/presence of reduced glutathione was also studied. Both HDM allergens and short-term (20 min) cigarette smoke exposure led to a significantly increased release of IL-8, IL-1beta and sICAM-1 from the epithelial cell cultures. Longer exposure (1-6 h) to cigarette smoke led to a dramatic decrease in the amount of these mediators detected in the culture medium. Whilst incubation of epithelial cultures with HDM allergen did not cause any significant change in the release of 51Cr from pre-loaded cells, cigarette smoke on its own led to a marked, exposure and incubation-time dependent increase in the release of 51Cr. Incubation with HDM allergen led to a significant, dose and time-dependent increase in the release of IL-8, which was further enhanced when the allergen extract was pre-activated with cysteine. This effect was completely abrogated by PTL11028, a novel Der p1 inhibitor. Prepared solutions of various concentrations of IL-8, IL-1beta and sICAM-1 exposed to cigarette smoke demonstrated a dramatic exposure time-dependent decrease in the detectable amount of these mediators, an effect which was abrogated by GSH. HDM-induced airway inflammation may include Der p-mediated release of inflammatory mediators from epithelial cells. Additionally, short-term cigarette smoke exposure may induce airway inflammation by release of inflammatory mediators from these cells, an effect which may be potentiated by Der p allergens. Longer term cigarette smoke exposure may cause damage to epithelial cells and changes in the structure of inflammatory mediators.

Fatty liver and elevated transaminases with heterozygous apolipoprotein B deficiency

Asymptomatic fatty liver and elevated transaminases is a common occurrence with varied etiology. Apolipoprotein (apo) B deficiency is an uncommon cause of fatty liver and elevated transaminases. The typical lipid profile low cholesterol low LDL (low density lipoprotein) suggests diagnosis of apo B deficiency and an invasive procedure like liver biopsy can be avoided in such patients.

Real time intraocular pressure and lamellar corneal flap thickness in keratomileusis

BACKGROUND

To measure real time intraocular pressure (IOP) during keratomileusis and to determine variability of corneal flap thickness by using different suction ring pressure settings.

METHODS

Eight human cadaver eyes, two groups of four each, were used. The suction ring of the UniversalKeratome was applied to each eye, the same as for a standard automated lamellar keratoplasty (ALK) or laser in situ keratomileusis (LASIK) procedure, to create a lamellar corneal flap. The pressure of the suction ring on each eye was raised to one of two different levels, four eyes to 488 and the remaining four to 600 mm Hg. IOP was continuously recorded by manometer, from application of the suction ring through the end of the passage of the microkeratome. Central corneal thickness was measured, both before and after each procedure.

RESULTS

IOP increased by >90 mm Hg after application of the suction ring at a pressure of either 488 mm Hg or 600 mm Hg. Corneal flaps performed under a suction ring pressure of 488 mm Hg measured 159.98+/-5 microm, whereas flap thickness for the 600-mm Hg group varied 1.4-266.2 microm. Two flaps exhibited irregular configurations.

CONCLUSIONS

Real time IOP can be measured during keratomileusis. The results demonstrated a significant increase in IOP during the procedure. Suction ring pressure setting is an important variable in determining consistent corneal flap thickness during the keratomileusis procedure.

Cigarette smoke decreases the expression of secretory component in human bronchial epithelial cells, in vitro

Epithelial secretory component (SC) is thought to be essential for immunologic protection of the respiratory tract from viral and bacterial infection, since it transports polymeric IgA from the basolateral to the luminal surface of epithelial cells. We have hypothesized that recurrent infection in airways of cigarette smokers is at least partly a consequence of cigarette smoke-induced downregulation of the expression and/or release of SC from airway epithelial cells, subsequently resulting in decreased transcytosis of secretory IgA to the airway lumen. To test this hypothesis, we have cultured human bronchial epithelial cells (HBEC) from surgical tissues and exposed these for 20 minutes to either air or cigarette smoke. Following exposure to cigarette smoke the HBEC cultures were incubated for a further period of up to 24 h, during which time separate cultures were processed by immunocytochemistry for the presence of SC, in a time-dependent manner. The stained HBEC cultures were evaluated by colour image analysis for the percentage of total cells staining for SC. Exposure to cigarette smoke significantly decreased the percentage of total HBEC staining for secretory component from a baseline value (median and interquartile[IQ]1, IQ3) of 35.9% (26.5, 41.6) to 15.7% (8.2, 25.4; p < 0.05) 1 h after exposure, compared with exposure to air. The percentage of cells staining for secretory component were further reduced to 5.3% (3.3, 6.4; p < 0.01), 6 h after exposure, compared to exposure to air. After incubation for 24 h following exposure to cigarette smoke, there was gross cell damage and the cells were not suitable for immunocytochemical analysis. These results suggest that short-term exposure to cigarette smoke may compromise the immune barrier function of the airway mucosa by decreasing the expression and/or release of epithelial SC, thereby decreasing the transcytosis of IgA necessary for inactivating the microbial pathogens in the airway lumen.

Prevention of perinatal HIV transmission during pregnancy

Transmission of the human immunodeficiency virus (HIV) from mother to child can occur in utero, during labour or after delivery from breastfeeding. The majority of infants are infected during delivery. Maternal HIV-1 plasma viral load at delivery is the most important predictor of vertical transmission. For this reason, efforts to interrupt transmission have focused on the use of antiretroviral therapy. Zidovudine has been shown to reduce significantly vertical HIV transmission when used antepartum and intrapartum by the mother and postpartum by the newborn for 6 weeks. However, zidovudine monotherapy increases the risk of developing zidovudine resistance and may jeopardize the goal of durable viral suppression and allow HIV disease progression in the mother and transmission to the infant. Potent antiretroviral therapy is now recommended for all HIV-infected pregnant women using the same criteria for non-pregnant individuals. If possible, combination antiretroviral regimens should include the use of zidovudine but not at the expense of long-term viral suppression. The use of elective Caesarean section should probably be reserved for women who fail to achieve viral suppression at the time of delivery or if indicated for obstetrical reasons. The practice of breastfeeding has been shown to diminish the long-term efficacy of perinatal antiretroviral therapy. All HIV-infected mothers should avoid breastfeeding the newborn if possible. This review summarizes major prospective and retrospective antiretroviral treatment studies in HIV-infected pregnant women. Pharmacokinetic information as it relates to pregnancy and adverse event profiles of antiretroviral agents are also discussed. The impact of recent advances in the management of HIV infection in pregnancy is discussed with regard to their feasibility in resource-poor countries.

Management of HIV infection during pregnancy

Optimal management of HIV infection in pregnancy requires maternal use of potent antiretroviral therapy to prevent disease progression in the mother and vertical transmission to the newborn. Combination antiretroviral therapy substantially reduces the risk of perinatal HIV transmission and appears to be more effective than zidovudine monotherapy. The administration of single dose nevirapine to mother intrapartum and infant postpartum effectively reduces vertical HIV transmission and is less costly and cumbersome than zidovudine regimens. Elective cesarean section reduces vertical transmission of HIV but its benefit is less clear when antiretroviral therapy decreases maternal plasma HIV viral load to low levels at delivery. If possible, HIV-infected mothers should avoid breastfeeding. The present review discusses the importance of early identification of maternal HIV infection, strict adherence to combination antiretroviral regimens to prevent drug resistance, developing a better understanding of antiretroviral pharmacokinetics in pregnancy and short/long term safety of anti-HIV drugs.

Risks associated with renal dysfunction in patients in the coronary care unit

OBJECTIVES

The purpose of this study was to quantify the impact of baseline renal dysfunction on morbidity and mortality in patients in the coronary care unit (CCU).

BACKGROUND

The presence of renal dysfunction is an established independent predictor of survival after acute myocardial infarction and revascularization procedures.

METHODS

We analyzed a prospective CCU registry of 12,648 admissions by 9,557 patients over eight years at a single, tertiary center. Admission serum creatinine was available in 9,544 patients. Those not on long-term dialysis were classified into quartiles of corrected creatinine clearance, with cut-points of 46.2, 63.1 and 81.5 ml/min per 72 kg. Dialysis patients (n = 527) were considered as a fifth comparison group.

RESULTS

Baseline characteristics, including older age, African-American race, diabetes, hypertension, previous coronary disease and heart failure, were incrementally more common across increasing renal dysfunction strata. There were graded increases in the relative risk for atrial and ventricular arrhythmias, heart block, asystole, development of pulmonary congestion, acute mitral regurgitation and cardiogenic shock across the risk strata. Survival analysis demonstrated an early mortality hazard for those with renal dysfunction, but not on dialysis, for the first 60 months, followed by graded decrements in survival across increasing renal dysfunction strata.

CONCLUSIONS

Baseline renal function is a powerful predictor of short- and long-term events in the CCU population. There is an early hazard for in-hospital and postdischarge mortality for those with a corrected creatinine clearance <46.2 ml/min per kg, but not on dialysis.

Cytokeratin expression in the odontogenic keratocyst

PURPOSE

This study attempted to identify differential cytokeratin expression in cystic jaw lesions using immunohistochemical staining.

PATIENTS AND METHODS

The charts from selected patients treated between 1983 and 1994 for jaw cysts were evaluated. Twenty-four paraffinized specimens were selected randomly for investigation with 5 immunohistochemical stains. The 4 diagnostic categories included ameloblastoma, dentigerous cyst, odontogenic keratocyst (OKC), and recurrent odontogenic keratocyst in patients with nevoid basal cell carcinoma (NBCC) syndrome. The 5 immunohistochemical stains included antibodies to cytokeratins 13, 17, and 18; CAM 5.2; AE 1/3; and carcinoembryonic antigen (CEA).

RESULTS

Differential staining of OKCs from patients with and without NBCC syndrome was found only with the antibody to cytokeratin 17. Furthermore, staining of OKCs in syndromic patients appeared to be stronger and more uniform than in nonsyndromic patients.

CONCLUSIONS

These findings suggest that immunohistochemical staining for cytokeratin 17 may aid in the diagnosis of OKCs and may be used to further subdivide these lesions based on the presence or absence of NBCC syndrome.

Quantitative topographic irregularity as a predictor of spectacle-corrected visual acuity after refractive surgery

PURPOSE

To evaluate a new topographic index called topographic irregularity as a quantitative predictor of corrected vision after refractive surgery.

METHODS

We defined topographic irregularity as the summed difference at all points between a topographic refractive corneal power map and its best-fit spherocylinder. We prospectively studied 107 eyes of 107 patients 3 months after a variety of refractive procedures. Topographic irregularity was calculated from topographic maps, and the correlation between topographic irregularity and spectacle-corrected visual acuity was determined using both high-contrast and low-contrast acuity charts. This correlation was compared with correlations for the surface regularity index and the surface asymmetry index. Next, we analyzed 54 of these topographic maps to create a regression scale relating surface regularity index, surface asymmetry index, and topographic irregularity to predict spectacle-corrected visual acuity. This scale was then used to predict spectacle-corrected visual acuity on the remaining 53 postoperative patients.

RESULTS

The correlation of topographic irregularity with spectacle-corrected visual acuity (R(2) =.36) was comparable to the correlation for the surface regularity index (R(2) =.36) and stronger than for the surface asymmetry index (R(2) =.11) when spectacle-corrected visual acuity was measured with high-contrast eye charts. Topographic irregularity correlated more strongly with spectacle-corrected visual acuity (R(2) =.42) than either the surface regularity index (R(2) =.28) or the surface asymmetry index (R(2) =.14) when spectacle-corrected visual acuity was measured with low-contrast eye charts. Using the regression scale, prediction of high-contrast and low-contrast spectacle-corrected visual acuity from topographic irregularity was superior to or comparable to predictions using the surface regularity index and the surface asymmetry index.

CONCLUSIONS

Topographic irregularity has a closer correlation with spectacle-corrected visual acuity than existing topographic indexes. Topographic irregularity is also an accurate predictor of spectacle-corrected visual acuity and may be a more sensitive tool for evaluating postoperative visual performance than current topographic measures.

Diagnosis and Management of Infectious Thyroiditis

A broad range of disorders can cause inflammation of the thyroid gland. True thyroid infections are rare and can result from a variety of microorganisms, of which bacteria are the most common. Other rarer pathogens include fungi, parasites, and viruses. Gram-positive bacteria, especially staphylococci, predominate as causative agents in adults and children. In immunocompromised patients, opportunistic pathogens have been isolated. Most infections in adults occur as a result of hematogenous or lymphatic seeding of the thyroid gland. In children, congenital anomalies can lead to thyroid infection and require surgical correction to prevent recurrence. Fine-needle aspiration of the thyroid is usually required to identify the infecting agent, and prolonged antimicrobial therapy with or without surgical drainage is the cornerstone of management. This review outlines the pathogenesis, microbiology, diagnosis, and management of infectious thyroiditis in adults and children and compares this disorder with other, more common causes of thyroid inflammation.

Phase Behavior, Structure, and Physical Properties of the Quaternary System Tetradecyldimethylamine Oxide, HCl, 1-Hexanol, and Water

The phase diagram of the ternary surfactant system tetradecyldimethylamine oxide (TDMAO)/HCl/1-hexanol/water shows with increasing cosurfactant concentration an L(1) phase, two L(alpha) phases (a vesicle phase L(alpha1) and a stacked bilayer phase L(alphah)), and an L(3) phase, which are separated by the corresponding two-phase regions L(1)/L(alpha) and L(alpha)/L(3). In this investigation, the system was studied where some of the TDMAO was substituted by the protonated TDMAO. Under these conditions, one finds for constant surfactant concentration of 100 mM TDMAO a micellar L(1) phase, an L(alpha1) phase (consisting of multilamellar vesicles), and an interesting isotropic L(1)(*) phase in the middle of the L(1)/L(alpha) two-phase region. The L(1)(*) phase exists at intermediate degrees of charging of 30-60% and for 40-120 mM TDMAO and 70-140 mM hexanol concentration. At surfactant concentrations less than 80 mM the L(1)(*)-phase borders directly on the L(1) phase. The phase transition between the L(1) phase and the L(1)(*) phase was detected by electric conductivity and rheological measurements. The conductivity values show a sharp drop at the L(1)/L(1)(*) transition, and the zero shear viscosity of the L(1)(*) phase is much lower than in L(1) phase. The form and size of the aggregates in L(1)(*) were detected with FF-TEM and SANS. This phase contains small unilamellar vesicles (SUV) of about 10 nm and some large multilamellar vesicles with diameters up to 500 nm. The system exhibits another peculiarity. For 100 mM surfactant, the clear L(alpha1)-phase exists only at chargings below 30%. With oscillating rheological measurements a parallel development of the storage modulus G' and the loss modulus G" was observed. Both moduli are frequency independent and the system possesses a yield stress. The storage modulus is a magnitude larger than the loss modulus. Copyright 2000 Academic Press.