Evaluation of high dose N- Acetylcysteine on airway inflammation and quality of life outcomes in adults with bronchiectasis: A randomised placebo-controlled pilot study

BACKGROUND

High dose N acetylcysteine (NAC), a mucolytic, anti-inflammatory and antioxidant agent has been shown to significantly reduce exacerbations, and improve quality of life in placebo controlled, double blind randomised (RCT) studies in patients with COPD, and in an open, randomised study in bronchiectasis. In this pilot, randomised, double-blind, placebo-controlled study, we wished to investigate the feasibility of a larger clinical trial, and the anti-inflammatory and clinical benefits of high dose NAC in bronchiectasis.

AIMS

Primary outcome: to assess the efficacy of NAC 2400 mg/day at 6 weeks on sputum neutrophil elastase (NE), a surrogate marker for exacerbations. Secondary aims included assessing the efficacy of NAC on sputum MUC5B, IL-8, lung function, quality of life, and adverse effects.

METHODS

Participants were randomised to receive 2400 mg or placebo for 6 weeks. They underwent 3 visits: at baseline, week 3 and week 6 where clinical and sputum measurements were assessed.

RESULTS

The study was stopped early due to the COVID pandemic. In total 24/30 patients were recruited, of which 17 completed all aspects of the study. Given this, a per protocol analysis was undertaken: NAC (n = 9) vs placebo (n = 8): mean age 72 vs 62 years; male gender: 44% vs 50%; baseline median FEV11.56 L (mean 71.5 % predicted) vs 2.29L (mean 82.2% predicted). At 6 weeks, sputum NE fell by 47% in the NAC group relative to placebo (mean fold difference (95%CI: 0.53 (0.12,2.42); MUC5B increased by 48% with NAC compared with placebo. Lung function, FVC improved significantly with NAC compared with placebo at 6 weeks (mean fold difference (95%CI): 1.10 (1.00, 1.20), p = 0.045. Bronchiectasis Quality of life measures within the respiratory and social functioning domains demonstrated clinically meaningful improvements, with social functioning reaching statistical significance. Adverse effects were similar in both groups.

CONCLUSION

High dose NAC exhibits anti-inflammatory benefits, and improvements in aspects of quality of life and lung function measures. It is safe and well tolerated. Further larger placebo controlled RCT's are now warranted examining its role in reducing exacerbations.

High-volume patient-controlled epidural vs. programmed intermittent epidural bolus for labour analgesia: a randomised controlled study

The aim of neuraxial analgesia is to achieve excellent pain relief with the fewest adverse effects. The most recently introduced technique for epidural analgesia maintenance is the programmed intermittent epidural bolus. In a recent study, we compared this with patient-controlled epidural analgesia without a background infusion and found that a programmed intermittent epidural bolus was associated with less breakthrough pain, lower pain scores, higher local anaesthetic consumption and comparable motor block. However, we had compared 10 ml programmed intermittent epidural boluses with 5 ml patient-controlled epidural analgesia boluses. To overcome this potential limitation, we designed a randomised, multicentre non-inferiority trial using 10 ml boluses in each group. The primary outcome was the incidence of breakthrough pain and total analgesic intake. Secondary outcomes included motor block; pain scores; patient satisfaction; and obstetric and neonatal outcomes. The trial was considered positive if two endpoints were met: non-inferiority of patient-controlled epidural analgesia with respect to breakthrough pain; and superiority of patient-controlled epidural analgesia with respect to local anaesthetic consumption. A total of 360 nulliparous women were allocated randomly to patient-controlled epidural analgesia-only or programmed intermittent epidural bolus groups. The patient-controlled group received 10 ml boluses of ropivacaine 0.12% with sufentanil 0.75 μg.ml^-1 ; the programmed intermittent group received 10 ml boluses supplemented by 5 ml patient-controlled boluses. The lockout period was 30 min in each group and the maximum allowed hourly local anaesthetic/opioid consumption was identical between the groups. Breakthrough pain was similar between groups (11.2% patient controlled vs. 10.8% programmed intermittent, p = 0.003 for non-inferiority). Total ropivacaine consumption was lower in the PCEA-group (mean difference 15.3 mg, p < 0.001). Motor block, patient satisfaction scores and maternal and neonatal outcomes were similar across both groups. In conclusion, patient-controlled epidural analgesia is non-inferior to programmed intermittent epidural bolus if equal volumes of patient-controlled epidural analgesia are used to maintain labour analgesia and superior with respect to local anaesthetic consumption.

High-throughput human primary cell-based airway model for evaluating influenza, coronavirus, or other respiratory viruses in vitro

Influenza and other respiratory viruses present a significant threat to public health, national security, and the world economy, and can lead to the emergence of global pandemics such as from COVID-19. A barrier to the development of effective therapeutics is the absence of a robust and predictive preclinical model, with most studies relying on a combination of in vitro screening with immortalized cell lines and low-throughput animal models. Here, we integrate human primary airway epithelial cells into a custom-engineered 96-device platform (PREDICT96-ALI) in which tissues are cultured in an array of microchannel-based culture chambers at an air-liquid interface, in a configuration compatible with high resolution in-situ imaging and real-time sensing. We apply this platform to influenza A virus and coronavirus infections, evaluating viral infection kinetics and antiviral agent dosing across multiple strains and donor populations of human primary cells. Human coronaviruses HCoV-NL63 and SARS-CoV-2 enter host cells via ACE2 and utilize the protease TMPRSS2 for spike protein priming, and we confirm their expression, demonstrate infection across a range of multiplicities of infection, and evaluate the efficacy of camostat mesylate, a known inhibitor of HCoV-NL63 infection. This new capability can be used to address a major gap in the rapid assessment of therapeutic efficacy of small molecules and antiviral agents against influenza and other respiratory viruses including coronaviruses.

Refractory uterine atony: still a problem after all these years

Postpartum hemorrhage is a leading cause of maternal morbidity and mortality, and uterine atony is the leading cause of postpartum hemorrhage. Risk factors for uterine atony include induced or augmented labor, preeclampsia, chorio-amnionitis, obesity, multiple gestation, polyhydramnios, and prolonged second stage of labor. Although a risk assessment is recommended for all parturients, many women with uterine atony do not have risk factors, making uterine atony difficult to predict. Oxytocin is the first-line drug for prevention and treatment of uterine atony. It is a routine component of the active management of the third stage of labor. An oxytocin bolus dose as low as 1 IU is sufficient to produce satisfactory uterine tone in almost all women undergoing elective cesarean delivery. However, a higher bolus dose (3 IU) or infusion rate is recommended for women undergoing intrapartum cesarean delivery. Carbetocin, available in many countries, is a synthetic oxytocin analog with a longer duration than oxytocin that allows bolus administration without an infusion. Second line uterotonic agents include ergot alkaloids (ergometrine and methylergonovine) and the prostaglandins, carboprost and misoprostol. These drugs work by a different mechanism to oxytocin and should be administered early for uterine atony refractory to oxytocin. Rigorous studies are lacking, but methylergonovine and carboprost are likely superior to misoprostol. Currently, the choice of second-line agent should be based on their adverse effect profile and patient comorbidities. Surgical and radiologic management of uterine atony includes uterine tamponade using balloon catheters and compression sutures, and percutaneous transcatheter arterial embolization.

Programmed intermittent epidural bolus vs. patient-controlled epidural analgesia for maintenance of labour analgesia: a two-centre, double-blind, randomised study†

The programmed intermittent epidural bolus technique has shown superiority to continuous epidural infusion techniques, with or without patient-controlled epidural analgesia for pain relief, reduced motor block and patient satisfaction. Many institutions still use patient-controlled epidural analgesia without a background infusion, and a comparative study between programmed intermittent epidural bolus and patient-controlled epidural analgesia without a background infusion has not yet been performed. We performed a randomised, two-centre, double-blind, controlled trial of these two techniques. The primary outcome was the incidence of breakthrough pain requiring a top-up dose by an anaesthetist. Secondary outcomes included: motor block; pain scores; patient satisfaction; local anaesthetic consumption; and obstetric and neonatal outcomes. We recruited 130 nulliparous women who received initial spinal analgesia, and then epidural analgesia was initiated and maintained with either programmed intermittent epidural bolus or patient-controlled epidural analgesia using ropivacaine 0.12% with sufentanil 0.75 µg·ml^-1 . The programmed intermittent epidural bolus group had a programmed bolus of 10 ml every hour, with on-demand patient-controlled epidural analgesia boluses of 5 ml with a 20 min lockout, and the patient-controlled epidural analgesia group had a 5 ml bolus with a 12 min lockout interval; the potential maximum volume per hour was the same in both groups. The patients in the programmed intermittent epidural bolus group had less frequent breakthrough pain compared with the patient-controlled epidural analgesia group, 7 (10.9%) vs. 38 (62.3%; p < 0.0001), respectively. There was a significant difference in motor block (modified Bromage score ≤ 4) frequency between groups, programmed intermittent epidural bolus group 1 (1.6%) vs. patient-controlled epidural analgesia group 8 (13.1%); p = 0.015. The programmed intermittent epidural bolus group had greater local anaesthetic consumption with fewer patient-controlled epidural analgesia boluses. Patient satisfaction scores and obstetric or neonatal outcomes were not different between groups. In conclusion, we found that a programmed intermittent epidural bolus technique using 10 ml programmed boluses and 5 ml patient-controlled epidural analgesia boluses was superior to a patient-controlled epidural analgesia technique using 5 ml boluses and no background infusion.

Effect of ritonavir-induced cytochrome P450 3A4 inhibition on plasma fentanyl concentrations during patient-controlled epidural labor analgesia: a pharmacokinetic simulation

BACKGROUND

Ritonavir inhibition of cytochrome P450 3A4 decreases the elimination clearance of fentanyl by 67%. We used a pharmacokinetic model developed from published data to simulate the effect of sample patient-controlled epidural labor analgesic regimens on plasma fentanyl concentrations in the absence and presence of ritonavir-induced cytochrome P450 3A4 inhibition.

METHODS

Fentanyl absorption from the epidural space was modeled using tanks-in-series delay elements. Systemic fentanyl disposition was described using a three-compartment pharmacokinetic model. Parameters for epidural drug absorption were estimated by fitting the model to reported plasma fentanyl concentrations measured after epidural administration. The validity of the model was assessed by comparing predicted plasma concentrations after epidural administration to published data. The effect of ritonavir was modeled as a 67% decrease in fentanyl elimination clearance. Plasma fentanyl concentrations were simulated for six sample patient-controlled epidural labor analgesic regimens over 24 h using ritonavir and control models. Simulated data were analyzed to determine if plasma fentanyl concentrations producing a 50% decrease in minute ventilation (6.1 ng/mL) were achieved.

RESULTS

Simulated plasma fentanyl concentrations in the ritonavir group were higher than those in the control group for all sample labor analgesic regimens. Maximum plasma fentanyl concentrations were 1.8 ng/mL and 3.4 ng/mL for the normal and ritonavir simulations, respectively, and did not reach concentrations associated with 50% decrease in minute ventilation.

CONCLUSION

Our model predicts that even with maximal clinical dosing regimens of epidural fentanyl over 24 h, ritonavir-induced cytochrome P450 3A4 inhibition is unlikely to produce plasma fentanyl concentrations associated with a decrease in minute ventilation.

Socioeconomic deprivation, readmissions, mortality and acute exacerbations of bronchiectasis

BACKGROUND

Bronchiectasis is known to cause significant morbidity in children in New Zealand. Little is known of the disease in adults.

AIM

Our objective was to characterise a cohort of adults who presented to hospital with acute exacerbations of the disease.

METHODS

We retrospectively collected information on all exacerbations treated as inpatients from a single hospital in South Auckland, New Zealand during 2002.

RESULTS

We collected information on 307 exacerbations in 152 patients. Twenty-seven per cent were of Maaori ethnic origin, and 44% Pacific. Seventy per cent lived in areas categorised as the 20% most deprived in New Zealand. Comorbid conditions were present in 80% of patients - most commonly chronic obstructive pulmonary disease, asthma, diabetes and cardiac disease. Seventy (46%) patients had at least one readmission and 32 patients (21%) died within 12 months of admission to hospital. Greater deprivation was associated with increased mortality at 12 months after admission after adjusting for other factors (OR 11, 95% CI 2.0-61, P= 0.006). In the subgroup who underwent high-resolution computed tomographic scanning (93), increasing severity of bronchiectasis (modified Bhalla score) was associated with readmission within 12 months (P= 0.004), but not mortality (P= 0.419).

CONCLUSIONS

We have shown that exacerbations of bronchiectasis in South Auckland are more common in patients who are predominantly of Maaori or Pacific descent and are socioeconomically deprived. Admission to hospital for an exacerbation is associated with high readmission and mortality rates.

[In vitro antibiotic susceptibility to fluoroquinolones]

OBJECTIVE

To determine the antibiotic susceptibility of bacteria recovered from cultures of ocular infections in the Fundación Oftalmológica de Santander - Clínica Carlos Ardila Lulle (FOSCAL).

MATERIALS AND METHODS

Retrospective descriptive study of a series of registries of cultures of samples from ocular surfaces and intraocular fluids from the OCULAB-FOSCAL laboratory in Floridablanca (Colombia) made between January and December of 2007. Antibiotic sensitivity screening by the method of Kirby-Bauer with impregnated Sensi-Discs™ of determined antibiotic concentrations was performed.

RESULTS

A total of 352 samples were studied: 160 from conjunctiva, 150 from cornea and 42 from intraocular fluids. Of the total of the samples more than one microorganism was recovered 45.65% of the samples. Gram positive and Gram negative bacteria were identified in 78.7 and 18.4%, respectively. Resistance to gatifloxacin, moxifloxacin, ciprofloxacin and levofloxacin was observed in 6.3, 8.9, 33.2 and 35.6%, respectively, of Gram positive bacteria. Resistance to gatifloxacin, moxifloxacin, ciprofloxacin and levofloxacin was also observed in 7.4, 16.7, 16.7%and 25.9%, respectively, of Gram negative bacteria. The overall bacterial resistance (Gram positive and Gram negative) to moxifloxacin was 10.15%, and to gatifloxacin it was 6.46%, being which showed a statistically significant difference (P<.05).

CONCLUSIONS

In our study the development of bacterial resistance to fourth generation fluoroquinolones was demonstrated in ocular samples. However, lower levels of resistance to fourth generation fluoroquinolones compared with that of third and second generation were found, particularly to Gram positive. Gatifloxacin showed lower resistance levels than moxifloxacin. Nevertheless, interpretation of this superiority must be made with caution in the clinical field, since other factors, like tissue penetration and in vivo activity, must be taken into account.

Low-dose ketamine with multimodal postcesarean delivery analgesia: a randomized controlled trial

BACKGROUND

Ketamine at subanesthetic doses has analgesic properties that have been shown to reduce postoperative pain and morphine consumption. We hypothesized that intravenous ketamine 10mg administered during spinal anesthesia for cesarean delivery, in addition to intrathecal morphine and intravenous ketorolac, would decrease the incidence of breakthrough pain and need for supplemental postoperative analgesia.

METHODS

Using a randomized double-blind placebo-controlled design, healthy women scheduled for cesarean delivery receiving hyperbaric spinal bupivacaine, fentanyl and morphine were randomized to intravenous ketamine 10mg or saline following delivery. Postoperative analgesia included scheduled ketorolac and acetaminophen/hydrocodone tablets as needed for breakthrough pain. The primary outcome was the incidence of breakthrough pain in the first 24h. Secondary outcomes included the number of acetaminophen/hydrocodone tablets administered and numeric rating scale for pain (0-10).

RESULTS

Group characteristics did not differ. There was no difference in the incidence of breakthrough pain (ketamine 75% VS. saline 74%, P=0.86). There was no difference in 24-h or 72-h use of supplemental acetaminophen/hydrocodone tablets between groups. Pain scores in the first 24h were similar, but lower in the ketamine compared to the saline group 2weeks postpartum (difference -0.6, 95% CI -1.1 to -0.9).

CONCLUSIONS

We found no additional postoperative analgesic benefit of low-dose ketamine during cesarean delivery in patients who received intrathecal morphine and intravenous ketorolac. Subjects who received ketamine reported lower pain scores 2weeks postpartum.

A comparison of the SNAP II™ and BIS XP™ indices during sevoflurane and nitrous oxide anaesthesia at 1 and 1.5 MAC and at awakening

BACKGROUND

Monitoring level of consciousness during anaesthesia, with the ability to predict the intentional or unintentional return to consciousness, is desirable. The purpose of this study was to compare two processed electroencephalographic depth of anaesthesia monitors (SNAP II and BIS XP) during sevoflurane and sevoflurane/nitrous oxide anaesthesia.

METHODS

In total, 42 subjects received an interscalene block, followed by general anaesthesia with sevoflurane or sevoflurane/nitrous oxide. The indices were recorded at baseline, at 1.5 and 1.0 minimum alveolar concentration (MAC) equivalents, and during emergence.

RESULTS

The SNAP and BIS indices decreased from baseline at 1.5 and 1.0 MAC equivalents, but there was no difference within groups between subjects who received nitrous oxide and those who did not. The SNAP index returned to baseline by 1 min before awakening and was higher than baseline at eye opening, but the BIS index remained below baseline at awakening. There was a bias of -1 (95% CI: -3 to 1) between the SNAP and BIS at baseline; this increased to 21 (95% CI: 19-23) during maintenance of anaesthesia and was 6 (95% CI: 4-8) at awakening.

CONCLUSIONS

The SNAP index tracks loss of consciousness and emergence from sevoflurane and sevoflurane/nitrous oxide anaesthesia. There is significant bias between the SNAP and BIS indices and therefore, the indices are not interchangeable. The SNAP index returns to baseline before awakening, whereas the BIS index remains below baseline at awakening, suggesting that the SNAP index may be more sensitive to unintentional awareness.

Efficacy and side effect profile of varying doses of intrathecal fentanyl added to bupivacaine for labor analgesia

The purpose of this randomized, double blinded and controlled study was to determine the optimal dose of intrathecal fentanyl when combined with bupivacaine 2.5 mg for initiation of labor analgesia. Parous parturients with cervical dilation between 3 and 5 cm were randomized to receive intrathecal fentanyl 0 (control), 5, 10, 15, 20 or 25 micrograms, combined with bupivacaine 2.5 mg, followed by a lidocaine/epinephrine epidural test dose. Visual analog pain scores (VAPS) and the presence of side effects were determined every 15 min until the parturient requested additional analgesia. Fetal heart rate (FHR) tracings were compared between groups. All parturients who received fentanyl >/= 15 micrograms had VAPS < 20 mm and duration of analgesia > 15 min, but this was not true for all parturients with fentanyl doses < 15 micrograms. Duration of analgesia was shorter for fentanyl groups 0, 5 and 10 micrograms, compared to groups 15, 20 and 25 micrograms, but there was no difference between the 15, 20 and 25 micrograms groups. There was no difference in the incidence of nausea and vomiting, or in FHR tracing changes. The incidence of pruritus was greater in all fentanyl groups compared to control. These data suggest that, when combined with intrathecal bupivacaine 2.5 mg, fentanyl 15 micrograms provides satisfactory analgesia to all parturients. Higher fentanyl doses produced no additional benefit in duration or quality of analgesia.

Adverse effects of oral corticosteroids in relation to dose in patients with lung disease

BACKGROUND

The adverse effects of oral corticosteroids are widely recognised but there are few quantitative data on which to base advice to patients. In a two part cross sectional study we compared adverse effects in patients with lung disease taking oral corticosteroids and control subjects and related the adverse effects to corticosteroid dose in the patient group.

METHODS

Data on oral corticosteroid use, lifestyle, fractures, and other possible adverse effects were collected by questionnaire and compared between a community based cohort of patients taking continuous or frequent intermittent oral corticosteroids for asthma, chronic obstructive pulmonary disease, or alveolitis and age and sex matched control subjects. Dose related effects were explored in the corticosteroid group using cumulative dose quartiles and multiple logistic regression.

RESULTS

A total of 367 patients (> or = 50 years, 48% female) and 734 control subjects completed the questionnaire. The cumulative incidence of fractures since the time of diagnosis was 23% for patients taking oral corticosteroids and 15% in the control group (odds ratio (OR) 1.8; 95% confidence interval (CI) 1.3 to 2.6). Patients were more likely to have had a fracture of the vertebrae (OR 10; 95% CI 2.9 to 34), hip (OR 6; 95% CI 1.2 to 30), and ribs or sternum (OR 3.2, 95% CI 1.6 to 6.6) than control subjects. They also reported a significant increase in cataracts, use of antacids, muscle weakness, back pain, bruising, oral candidiasis, and having fewer teeth. The effects of oral corticosteroids were dose related: the odds ratio for patients in the highest compared with the lowest cumulative dose quartile (median prednisolone dose 61 g versus 5 g) ranged from 2 for all fractures to 9 for vertebral fractures and bruising.

CONCLUSIONS

By quantifying the morbidity associated with the use of oral corticosteroids, this study should help to rationalise their long term use.

The dose-response of intrathecal sufentanil added to bupivacaine for labor analgesia

BACKGROUND

Regional analgesia for labor often is initiated with an intrathecal injection of a local anesthetic and opioid. The purpose of this prospective, randomized, blinded study was to determine the optimal dose of intrathecal sufentanil when combined with 2.5 mg bupivacaine for labor analgesia.

METHODS

One hundred seventy parous parturients with cervical dilation between 3-5 cm were randomized to receive intrathecal 0 (control), 2.5, 5.0, 7.5, or 10.0 microg sufentanil combined with 2.5 mg bupivacaine, followed by a lidocaine epidural test dose, for initiation of analgesia (34 patients in each group). Visual analog scores and the presence of nausea, vomiting, and pruritus were determined every 15 min until the patient requested additional analgesia. Fetal heart rate tracings were compared between groups.

RESULTS

Groups were similar for age, height, weight, oxytocin dose, duration of labor, and baseline visual analog scores. Duration of action was significantly shorter for control patients (39 +/- 25 min [mean +/- SD]) compared with those administered sufentanil, all doses (93 +/- 32, 93 +/- 47, 94 +/- 33, 97 +/- 39 min), but was not different among groups administered 2.5, 5.0, 7.5, or 10.0 microg sufentanil. More patients who received 10 microg sufentanil reported nausea and vomiting than did control patients. The severity of pruritus increased with administration of 7.5 and 10.0 microg sufentanil. There was no difference in fetal heart rate changes among groups.

CONCLUSIONS

Intrathecal bupivacaine (2.5 mg) without sufentanil did not provide satisfactory analgesia for parous patients. However, bupivacaine combined with 2.5 microg sufentanil provided analgesia comparable to higher doses, with a lower incidence of nausea and vomiting and less severe pruritus.

Is the management of epidural analgesia associated with an increased risk of cesarean delivery?

OBJECTIVE

The aim of this study was to quantify the association of cesarean delivery with epidural analgesia management, specifically with the timing of epidural catheter placement in relation to labor, the type of epidural analgesia, and the use of bolus dosing.

STUDY DESIGN

A retrospective cohort design was used to investigate 1561 consecutive nulliparous parturients whose labor occurred between November 1, 1996, and June 30, 1997, at Northwestern Memorial Hospital and who were delivered of term, singleton neonates in a cephalic presentation. The relationship between the management of epidural analgesia and the risk for cesarean delivery was determined with stepwise logistic regression to control for potential confounding variables.

RESULTS

There was a significantly increased risk of cesarean delivery associated with decrements in cervical effacement (P =.001), cervical dilatation (P =.001), and fetal station (P =.001) at the time of epidural catheter placement. An increasing number of epidural boluses during the first stage of labor was also associated with increased risk of cesarean delivery (P =.001). After we controlled for maternal age, maternal body mass index, gestational age, infant birth weight, induction of labor, use of magnesium sulfate, and presence of chorioamnionitis, the adjusted odds of cesarean delivery associated with fetal station (odds ratio, 1.45; 95% confidence interval, 1.2-1.7) and epidural boluses (odds ratio, 1.55; 95% confidence interval, 1.3-1.8) during the first stage of labor remained significant.

CONCLUSION

The management of epidural analgesia during labor was associated with the potential for increased risk of cesarean delivery. This risk increased with higher stations of the fetal head at the time of epidural catheter placement and with more frequent epidural boluses of local anesthetic during the first stage of labor.

Inhaled corticosteroid use and bone-mineral density in patients with asthma

BACKGROUND

Inhaled corticosteroids are absorbed into the systemic circulation, but the extent to which they have adverse effects on bone is uncertain. The question is important since 3% of the European population take an inhaled corticosteroid regularly and may do so for many years.

METHODS

We studied the dose-response relation between cumulative inhaled corticosteroid dose and bone-mineral density at the lumbar spine and proximal femur in 196 adults (119 women) with asthma aged 20-40 years. Patients had taken an inhaled corticosteroid regularly for at least 6 months, and had had limited exposure to systemic steroids. Cumulative dose of inhaled corticosteroid was calculated from questionnaires and computerised and written general-practice records, and its effect on bone-mineral density was estimated by multiple regression analysis.

FINDINGS

Median duration of inhaled corticosteroid treatment was 6 years (range 0.5-24), and median cumulative dose was 876 mg (87-4380). There was a negative association between cumulative dose of inhaled corticosteroid and bone-mineral density at the lumbar spine (L2-L4), femoral neck, Ward's triangle, and trochanter, both before and after adjustment for the effects of age and sex. A doubling in dose of inhaled corticosteroid was associated with a decrease in bone-mineral density at the lumbar spine of 0.16 SD (95% CI 0.04-0.28). Similar decreases were found at the femoral neck, Ward's triangle, and trochanter. Adjustment for potential confounding factors including physical activity and past oral, nasal, dermal, and parenteral corticosteroids did not weaken the associations.

INTERPRETATION

This study provides evidence of a negative relation between total cumulative dose of inhaled corticosteroid and bone-mineral density in patients with asthma.

Molecular analysis of trkC in the cat visual cortex

trkC belongs to the trk family of neurotrophin receptors. Several isoforms of trkC have been cloned to date; a full-length catalytic form containing a tyrosine kinase (TK) domain, three full-length isoforms with amino-acid insertions (14, 25, and 39 amino acids) in the TK domain, and five noncatalytic truncated forms that completely lack the TK domain. These isoforms have been studied in several mammalian species, including the pig, rat, mouse, monkey, and human. In this article we report the cloning and sequencing of five trkC isoforms isolated from 30-d postnatal cat visual cortex. The first isoform corresponded to the previously reported full-length trkC transcript containing the 14 amino-acid insert. To search for the presence of other inserts, reverse transcription polymerase chain reaction (RT-PCR) was performed on 30-d postnatal cat visual cortex mRNA using primers that flank the insertion site in the TK domain. Both the isoform containing the 14 amino-acid insert and the isoform lacking any insertion were present in abundant amounts, whereas the other two insert containing isoforms (TK25 and TK39) were much less abundant. The fifth isoform discovered corresponds to the previously reported truncated transcript. Overall, there is a high degree of identity (89-98%) and homology (97-99%) between the cat trkC nucleotide and amino-acid sequences among all mammals. The extracellular juxtamembrane domain was found to be highly divergent among all mammals that have been studied to date. This divergent region also included a proline deletion in the cat trkC sequence. This is the first report of the cloning, sequencing, and RT-PCR analysis of trkC in cat visual cortex, a system extensively studied using anatomical and physiological approaches.

Experimental gene therapy for an in vitro model of proliferative vitreoretinopathy

BACKGROUND

Proliferative vitreoretinopathy (PVR) is the leading cause of failure of retinal reattachment surgery. Since a key component of PVR is cell proliferation, we performed a study to examine whether the ribonucleotide-reductase-deficient herpes simplex virus type I (HSV-I) mutant hrR3 can be effective at destroying proliferating retinal pigment epithelial (RPE) cells and thus prevent epiretinal membrane formation and PVR, while sparing nondividing cells, such as neurons.

METHODS

Primary cultures of rat RPE cells and rat cortical neurons were infected with 300 microL of hrR3 HSV-I to achieve a multiplicity of infection of 1.0. After 1 hour at 37 degrees C, 700 microL of growth medium was added to raise the total volume of medium to 1 mL. At 0, 12, 24 and 36 hours the cultures were observed, and the ratio of dead cells to live cells was determined. HSV infection and protein expression were confirmed by a beta-galactosidase histochemical assay or an antihuman HSV-I immunoassay, or both.

RESULTS

At 24 hours more than 95% of the RPE cells and neurons stained positively for HSV infection, although beta-galactosidase was expressed predominantly in RPE cells. At 36 hours 72% (standard deviation 2.1%) of the RPE cells were dead. There was no noticeable cell death in the neuronal or mock-infected control cultures.

INTERPRETATION

The results suggest that the hrR3 mutant strain of HSV-I can be used to infect and selectively kill actively proliferating rat RPE cells while sparing normal, nonreplicating cells. This model may be used to explore potential therapies for PVR in humans.

Morbidity from asthma in relation to regular treatment: a community based study

BACKGROUND

The extent to which asthma morbidity in the community occurs in patients who are having relatively little treatment or in those on step 3 or above of the British asthma management guidelines is uncertain. We have looked at this in a community population in southern Nottinghamshire.

METHODS

A cross sectional review of treatment in all patients over the age of four with diagnosed asthma was carried out in five large general practices (population 38 865) in 1995/6 using computerised general practice records. The patients' usual treatment was obtained from prescription data and categorised by the appropriate step on the British guidelines on asthma management. Two measures of morbidity, the request for 10 or more short acting beta agonist inhalers a year or the need for a course of oral corticosteroids in the last year, were related to the regular treatment of the patients.

RESULTS

Of the 3373 patients (8. 7%) given a diagnosis of asthma, the percentage on steps 1, 2, 3, 4, and 5 of treatment were 54%, 22%, 11%, 3.6%, and 1%, respectively, with a further 8% having had no treatment. During the past year 13. 6% had been prescribed 10 or more beta agonist inhalers and 12.5% had received at least one course of oral corticosteroids. Both measures occurred more frequently in patients taking more prophylactic treatment (step 3 or above). Nevertheless, because most patients were on steps 1 and 2 of the treatment guidelines, more than half the patients requiring high doses of inhaled beta agonists or a course of oral prednisolone came from those taking low dose or no regular inhaled corticosteroid.

CONCLUSIONS

Evidence of morbidity from asthma was found in many patients taking little or no prophylactic medication and this should be amenable to improved education. A different approach may be needed for patients with continuing morbidity who are already taking higher doses of prophylactic medication.

Transduction of primitive human marrow and cord blood-derived hematopoietic progenitor cells with adeno-associated virus vectors

We evaluated the capacity of adeno-associated virus (AAV) vectors to transduce primitive human myeloid progenitor cells derived from marrow and cord blood in long-term cultures and long-term culture-initiating cell (LTC-IC) assays. Single-colony analyses showed that AAV vectors transduced CD34(+) and CD34(+)38(-) clonogenic cells in long-term culture. Gene transfer was readily observed in LTC-ICs derived from 5-, 8-, and 10-week cultures. Recombinant AAV (rAAV) transduction was observed in every donor analyzed, although a wide range of gene transfer frequencies (5% to 100%) was noted. AAV transduction of LTC-ICs was stable, with week-8 and -10 LTC-ICs showing comparable or better transduction relative to week-5 LTC-ICs. Fluorescence in situ hybridization (FISH) analyses performed to determine the fate of AAV vectors in transduced cells showed that 9% to 28% of CD34(+) and CD34(+)38(-) cells showed stable vector integration as evidenced by chromosome-associated signals in metaphase spreads. Comparisons of interphase and metaphase FISH suggested that a fraction of cells also contained episomal vector at early time points after transduction. Despite the apparent loss of the episomal forms with continued culture, the number of metaphases containing integrated vector genomes remained stable long term. Transgene transcription and placental alkaline phosphatase (PLAP) expression was observed in CD34(+), CD34(+)38(-) LTC-ICs in the absence of selective pressure. These results suggest that primitive myeloid progenitors are amenable to genetic modification with AAV vectors.

The incidence of transient radicular irritation after spinal anesthesia in obstetric patients

BACKGROUND AND OBJECTIVES

Transient radicular irritation (TRI) has been described after spinal anesthesia, particularly with 5% hyperbaric spinal lidocaine. The purpose of this study was to determine the incidence of TRI in obstetric patients.

METHODS

All obstetric patients undergoing spinal anesthesia during a 9-month period were enrolled in the study (n = 303). Details of the anesthetic technique were recorded at the time of anesthesia. A blinded anesthesia nurse contacted each patient on postoperative day 2 and asked about symptoms of TRI.

RESULTS

Most patients received either intrathecal hyperbaric bupivacaine 0.75 % (n = 232) or lidocaine 5 % (n = 67) through pencil-point needles. Cerebrospinal fluid was used to dilute the spinal lidocaine in 63% of patients. Patients receiving bupivacaine were more often in the supine position, underwent significantly longer procedures, and more often received intrathecal opioid. The incidence of TRI after lidocaine spinal anesthesia was 0% (95% confidence interval 0-4.5%).

CONCLUSIONS

The incidence of TRI after spinal lidocaine anesthesia in the obstetric population is low.

Use of oral corticosteroids in the community and the prevention of secondary osteoporosis: a cross sectional study

OBJECTIVE

To determine the prevalence of continuous use of oral steroids in the general population, the conditions for which they are prescribed, and the extent to which patients taking oral steroids are taking treatment to prevent osteoporosis.

DESIGN

A cross sectional study with a four year retrospective review of drug treatment.

SETTING

Eight large general practices in central and southern Nottinghamshire.

SUBJECTS

A population of 65,786 patients (52% women) registered with a general practitioner during 1995.

RESULTS

303 patients (65% (197) women) aged 12-94 years were currently taking "continuous" (for at least three months) oral corticosteroid treatment. This figure represents 0.5% of the total population and 1.4% (245/17 114) of patients aged 55 years or more (1.7% (166/9601) of women). The usual steroid was prednisolone (97% (294/303)), the mean dose was 8.0 mg/day, and the median duration of oral steroid treatment determined in 149 patients was three years. The most common conditions for which continuous oral steroids were prescribed were rheumatoid arthritis (23% (70)), polymyalgia rheumatica (22% (66)), and asthma or chronic obstructive airways disease (19% (59)). Only 41 (14%) of the 303 patients taking oral steroids had received treatment for the prevention of osteoporosis over the past four years. Although 37 of the 41 patients were women, only 10% (18/181) of the women over 45 years taking continuous oral corticosteroids were currently taking hormone replacement therapy.

CONCLUSIONS

If our figures are typical then they suggest that over 250,000 people in the United Kingdom are taking continuous oral steroids and that most of these are taking no prophylaxis against osteoporosis.

Pulmonary function before and after anterior spinal surgery in adult idiopathic scoliosis

BACKGROUND

Little is known about the long term effects of anterior spinal surgery on pulmonary function in adult patients with idiopathic scoliosis. A study was therefore undertaken of pulmonary function before and after anterior spinal surgery in this group of patients.

METHODS

Fourteen patients (12 women) of mean age 26.5 years (range 17-50, 10 > or = 20 years) were studied. All 14 patients underwent thoracotomy and anterior arthrodesis, and five also underwent posterior arthrodesis. Scoliosis curves and lung volumes were measured preoperatively and at a mean follow up of 32 months (range 14-49) after surgery.

RESULTS

At long term follow up after surgery the mean (SD) Cobb angle of the thoracic curve improved from 59 degrees (25 degrees) to 39 degrees (18 degrees), a correction of 31%. Despite this there was a fall in mean forced vital capacity (FVC) of 0.21 litres (95% confidence interval 0.04 to 0.38). In the patients who underwent anterior surgery without posterior surgery (n = 9) there was a fall in mean FVC of 0.31 litres (95% confidence interval 0.12 to 0.50); mean forced expiratory volume in one second and total lung capacity were also reduced and there was an increase in mean residual volume.

CONCLUSIONS

Forced vital capacity is reduced at long term follow up in adult patients with idiopathic scoliosis who undergo anterior spinal surgery. The fall in FVC is small and is unlikely to be of clinical significance in patients with reasonable lung function in whom surgery is planned for prevention of curve progression or improvement of cosmetic appearance and pain. However, surgical intervention should not be undertaken in an attempt to improve pulmonary function.

Comparison of thrombelastography with common coagulation tests in preeclamptic and healthy parturients

BACKGROUND AND OBJECTIVES

Epidural analgesia/anesthesia is often beneficial in the management and treatment of preeclampsia. However, some preeclamptic patients have a coagulopathy that is a contraindication to regional anesthesia. A routine coagulation battery (RCB) consisting of prothrombin time, partial thromboplastin time, platelet count, and bleeding time, is commonly performed to assess coagulation status. Thrombelastography (TEG) is a measure of clotting that allows evaluation of overall coagulation activity. The goal of this study was to examine whether TEG can predict normal and abnormal coagulation as diagnosed by RCB in healthy and preeclamptic parturients.

METHODS

Forty-seven parturients participated in this prospective study, performed early in the first stage of labor. Twenty healthy parturients (group I), 19 mild (group II), and 8 severe preeclamptic/eclamptic parturients (group III) had RCB and TEG performed.

RESULTS

Five patients (1, group I; 3, group II; 1, group III) had a normal RCB, but a mildly abnormal TEG (prolonged K, small alpha) (specificity = 0.88). Five of 27 preeclamptic parturients (1, group II; 4, group III) had abnormal RCBs. Three of these 5 patients had thrombocytopenia with normal bleeding times and TEGs. Two patients had thrombocytopenia and prolonged bleeding times and abnormal TEGs (sensitivity = 0.40).

CONCLUSION

Thrombelastography is not an effective means of predicting abnormal coagulation, as diagnosed by RCB, in preeclamptic parturients, using currently defined normal TEG values for nonpregnant patients. However, an abnormal TEG maximum amplitude value always correlated with a prolonged bleeding time. Therefore, TEG may be useful in assessing platelet function in the presence of thrombocytopenia. Further studies are warranted.

Streptococcus milleri pulmonary disease: a review and clinical description of 25 patients

BACKGROUND

Streptococcus milleri is increasingly being recognised as an important pulmonary pathogen which may lead to the development of empyema or lung abscess. Although several small series have been reported, the clinical and laboratory features have yet to be fully characterised.

METHODS

Twenty five cases were identified and the clinical and laboratory data from case records were analysed.

RESULTS

There were 16 empyemas, five lung abscesses, and four with both lung abscess and empyema. The mean age of the patients was 61 years (range 36-89) and 84% were men. The most common symptoms at presentation were shortness of breath, chest pain, cough, and weight loss; only 36% had a fever. Four of the nine patients with lung abscess required a diagnostic lobectomy because of suspected malignancy. Predisposing factors were present in 80% of patients and included the following: pneumonia, periodontal disease, excess alcohol intake, previous thoracic surgical procedures, and malignancy. Laboratory features of S milleri infection were leucocytosis, neutrophilia, anaemia, abnormal liver function tests, and hypoalbuminaemia. In the group with empyema five patients had a pneumothorax on initial presentation and pleural loculation occurred in 10 of these patients. The median stay in hospital was 34 days (range 11-88). Six patients died, five of whom had significant underlying illnesses.

CONCLUSIONS

Pulmonary infection with S milleri may result in considerable morbidity and mortality, and is characterised by a strong male predominance, non-specific symptoms (often without toxicity), the presence of predisposing factors, pleural loculation, pneumothorax, and a protracted stay in hospital.

Recombinant aprotinin in coronary artery bypass graft operations

OBJECTIVE

To evaluate the role of recombinant bovine aprotinin in reducing blood loss in coronary artery bypass graft surgery.

DESIGN

An open-label, randomized, controlled study evaluating two dosage levels of recombinant aprotinin.

SETTING

Two acute care hospitals (Northwestern Memorial Hospital, Chicago, Ill., and the Scott & White Memorial Hospital, Temple, Texas).

PATIENTS

Patients undergoing primary and reoperation coronary artery bypass grafting were assigned to groups by means of a computer-generated table of random numbers. Treated (n = 48) and control (n = 36) patients did not differ significantly in age, sex, weight, number of grafts, or preoperative hemoglobin level.

INTERVENTIONS

Recombinant aprotinin was given at two dosages. Dosage level 1 consisted of a bolus of 2 mg/kg intravenously immediately after the induction of anesthesia, 1 mg/kg added to each liter of the oxygenator prime, and 0.5 mg.kg-1.hr-1 infused continuously during operation. At dosage level 2, doses were doubled. Intraoperative monitoring of anti-factor Xa activity was performed, and additional doses of heparin were given on the basis of anti-factor Xa results.

MAIN OUTCOME MEASURES

Preoperative and postoperative hemoglobin levels, amounts of autotransfusion device and chest tube drainage blood, and transfusions of allogeneic red blood cells. Adverse clinical events (alterations in renal function, graft thrombosis, myocardial infarction, and death) were recorded.

RESULTS

Additional heparin was given to 48% patients in the aprotinin group and to 44% of control patients. Overall red blood cell loss (in milliliters, mean +/- standard deviation [SD]) was decreased with aprotinin at dosage level 1 for reoperations (1040 +/- 162 vs 1544 +/- 198, p < 0.01), and at dosage level 2 for all operations (primary operations, 886 +/- 362 vs 1333 +/- 618, p = 0.02; reoperations, 1191 +/- 560 vs 1815 +/- 1116, p = 0.2). Fewer patients in the aprotinin than in the control group had transfusions of donated blood (6/48 vs 12/36, p = 0.02) or reinfusion of chest tube drainage blood (12/48 vs 20/36, p < 0.01). Among patients receiving dosage level 1, there were no myocardial infarctions or deaths. At dosage level 2, one patient had profound bradycardia and died on day 12 and two patients had late graft closures. Two control patients had hypotension after bypass necessitating intraaortic balloon pumps, and one of these patients died. Postoperative increases in blood urea nitrogen and creatinine levels were small in both aprotinin and control groups. No hypersensitivity or other allergic reactions occurred.

CONCLUSION

We conclude that, at the dosages given, recombinant bovine aprotinin decreases surgical blood loss and transfusion requirements in patients undergoing coronary artery bypass grafting, but its use requires appropriate monitoring of heparin use during bypass. Whether higher dosages of aprotinin increase the risk of graft thrombosis must be further assessed with a larger patient sample.

The effect of low-dose bupivacaine on postoperative epidural fentanyl analgesia and thrombelastography

We performed a prospective, randomized, double-blind study to determine the effect of bupivacaine on postoperative epidural fentanyl analgesia and thrombelastography in 120 patients who underwent extensive gastrointestinal or genitourinary surgery. The patients were randomized into four groups, 30 patients per group: Group I = epidural fentanyl (EF), 10 micrograms/mL in saline; Group II = EF with 0.1% bupivacaine; Group III = EF with 0.15% bupivacaine; and Group IV = EF with 0.2% bupivacaine. Pain relief was evaluated by a visual analog scale (VAS), both at rest and during coughing, and by a visual rating scale (VRS). The VAS, VRS, degree of sedation, and side effects (nausea, vomiting, and pruritus) were evaluated every 2 h from 8:00 AM to 6:00 PM, for 24 h after surgery. Forced vital capacities (FVCs) were determined before surgery and at 24 h after surgery. Blood was withdrawn for thrombelastography (TEG) measurements preoperatively, in the recovery room (PARR), and 24 h postoperatively. The VAS, VRS, sedation scores, changes in postoperative FVCs, and the incidence of side effects were not statistically different among the four groups. The 24-h total volumes of infusion in the four groups (146 +/- 40 mL, 140 +/- 38 mL, 142 +/- 40 mL, 124 +/- 21 mL, respectively) were not statistically different from each other. There were no significant differences in the TEG values [reaction time (R), coagulation time (K), angle (alpha), and maximum amplitude (mA)] among the four groups at anytime nor was there any difference between the baseline, PARR, and 24-h TEG values within any group.(ABSTRACT TRUNCATED AT 250 WORDS)

Keeping it secret: the costs and benefits of nursing's hidden work in discharging patients

Workload analysts and nursing theorists alike continue their attempts to capture the hidden work of nursing, with varying degrees of success. An interpretative study of the process of discharging patients from hospital to care at home led to a new understanding of the context-related work which nurses do. Three components of context-related work were identified: working with the characteristics of bureaucracy; compensating for bureaucracy on behalf of the health care team; and providing leadership which ensured effective care from others. All constituted invaluable yet obscured and unrecognized components of nursing's indirect contribution to patient care. The costs to keeping this work 'secret' were readily apparent. The understanding derived from this research affords new insights into why nursing has kept this hidden work secret. These insights, in turn, help identify potential solutions for consideration by all concerned about nursing's professional role, status and identity.

Coagulation tests, blood loss, and transfusion requirements in platelet-rich plasmapheresed versus nonpheresed cardiac surgery patients

The results of several studies suggest that acute platelet-rich plasmapheresis decreases blood loss and allogeneic blood product transfusion requirements in cardiac surgery patients. We designed a randomized, prospective study to determine whether acute platelet-rich plasmapheresis decreases blood loss and allogeneic transfusion requirements in primary cardiac surgery patients. Forty patients were randomized to a control or pheresis group. The pheresis group had platelet-rich plasmapheresis performed before cardiopulmonary bypass (CPB) and the platelet-rich plasma (PRP) was returned after CPB. The control group was managed in the normal fashion without pheresis. All patients had serial coagulation studies, hemoglobin, and platelet counts determined intra- and postoperatively. Chest tube drainage and transfusion requirements were recorded. There were no differences in the coagulation tests, platelet counts, chest tube drainage, or allogeneic blood product transfusion requirements between the two groups at any time. The authors conclude that the use of acute platelet-rich plasmapheresis in primary cardiac surgery patients does not decrease chest tube drainage or the need for allogeneic blood transfusions.

Uncertainty and anxiety after mastectomy for breast cancer

The purpose of this study was to determine the relationship between uncertainty and anxiety in women after mastectomy for breast cancer and to describe women's responses to partial or complete mastectomy for breast cancer during the early rehabilitative phase after surgery. A theoretical framework for the study was derived from the Scott, Oberst, and Dropkin Stress-Coping Model and from a review of the literature. Major study variables and variable measures were uncertainty, measured by the Mishel Uncertainty in Illness Scale (MUIS), and anxiety, measured by the State-Trait Anxiety Inventory (STAI). Twenty-five women admitted to two acute-care teaching hospitals for their first partial or modified radical mastectomy made up the convenience sample of this study. Data were collected 1-2 days before and 1-2 weeks after hospital discharge. From study findings, it was shown that only at the postdischarge testing was there a significant positive correlation between uncertainty and state anxiety. The development of appropriate interventions to assist breast cancer patients in dealing with the fears of recurrence and uncertainties regarding treatment effectiveness and sequelae has relevance for nursing practice.

Preoperative patient preparation

Patients receive maximum benefit from surgery with the fewest complications if they and the medical personnel involved in their care are well prepared for anesthesia. The importance of a thorough history and physical examination are discussed. Controversial aspects of routine preoperative laboratory testing are reviewed, as are the effects of common chronic medications on anesthesia care. The role of preoperative medications and psychological preparation are reviewed. The importance of nothing-by-mouth status and the risk of acid aspiration are emphasized. A brief discussion of preoperative optimization of cardiopulmonary disease and the definition of American Society of Anesthesiologists Physical Status conclude the article.

Comparison of the effects of the acute administration of dexoxadrol, levoxadrol, MK-801 and phencyclidine on body temperature in the rat

Some of the dioxolanes produce pharmacological effects that have much in common with phencyclidine and phencyclidine-like drugs. Dioxadrol can be resolved into two enantiomers, dexoxadrol and levoxadrol. Dexoxadrol has an affinity for phencyclidine receptors that is much greater than that of levoxadrol, but dexoxadrol and levoxadrol have nearly equal affinities for sigma receptors. The systematic analysis of the relative potencies of dexoxadrol and levoxadrol can be used as an approach to define effects mediated by phencyclidine vs sigma receptors. Compounds that act on phencyclidine receptors, as well as affecting behavior, alter body temperature in the rat. The purpose of the present study was to compare and contrast the effects of the acute administration of dexoxadrol, levoxadrol, MK-801 and phencyclidine on body temperature in the rat. Dexoxadrol and levoxadrol (5.0, 10.0, 20.0 or 40.0 mg/kg), MK-801 (0.12, 0.6 or 1.2 mg/kg) or phencyclidine (5.0, 10.0 or 20.0 mg/kg) were administered subcutaneously and body temperature was measured. Both dexoxadrol and MK-801 produced hyperthermia but levoxadrol did not affect body temperature. In contrast to the hyperthermic effects of dexoxadrol and MK-801, phencyclidine produced hypothermia. These findings indicate that hypothermia induced by phencyclidine is not due to interactions with phencyclidine receptors and, while dexoxadrol, MK-801 and phencyclidine may share some similar receptor binding and behavioral characteristics, they can be differentiated on the basis of their effects on body temperature.

Factors related to early termination of breast-feeding in an urban population

A prospective study of breast-feeding mothers was undertaken to determine the effect of formula samples and other hospital-related factors on success in breast-feeding. Of the 166 nursing mothers studied for 4 months postpartum, 83% breast-fed for 1 month, 73% for 10 weeks, and 58% for 4 months or longer. Breast-feeding duration was not affected by formula samples given at discharge from the hospital. Factors correlating significantly with improved breast-feeding rates include maternal age, maternal education, nonsmoking, previous breast-feeding, planned pregnancy, initiation of breast-feeding in the first 16 hours, and minimization of formula supplementation in the nursery. Partial breast-feeding (supplementing more than one bottle of formula per day, measured at 1 month postpartum) was associated with shorter breast-feeding duration. This latter effect was minimized by frequent nursing (seven or more times per day), despite formula supplementation.