Intravascular imaging guided versus coronary angiography guided percutaneous coronary intervention: systematic review and meta-analysis

OBJECTIVE

To assess the absolute treatment effects of intravascular imaging guided versus angiography guided percutaneous coronary intervention in patients with coronary artery disease, considering their baseline risk.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed/Medline, Embase, and Cochrane Library databases up to 31 August 2023.

STUDY SELECTION

Randomized controlled trials comparing intravascular imaging (intravascular ultrasonography or optical coherence tomography) guided versus coronary angiography guided percutaneous coronary intervention in adults with coronary artery disease.

MAIN OUTCOME MEASURES

Random effect meta-analysis and GRADE (grading of recommendations, assessment, development, and evaluation) were used to assess certainty of evidence. Data included rate ratios and absolute risks per 1000 people for cardiac death, myocardial infarction, stent thrombosis, target vessel revascularization, and target lesion revascularization. Absolute risk differences were estimated using SYNTAX risk categories for baseline risks at five years, assuming constant rate ratios across different cardiovascular risk thresholds.

RESULTS

In 20 randomized controlled trials (n=11 698), intravascular imaging guided percutaneous coronary intervention was associated with a reduced risk of cardiac death (rate ratio 0.53, 95% confidence interval 0.39 to 0.72), myocardial infarction (0.81, 0.68 to 0.97), stent thrombosis (0.44, 0.27 to 0.72), target vessel revascularization (0.74, 0.61 to 0.89), and target lesion revascularization (0.71, 0.59 to 0.86) but not all cause death (0.81, 0.64 to 1.02). Using SYNTAX risk categories, high certainty evidence showed that from low risk to high risk, intravascular imaging was likely associated with 23 to 64 fewer cardiac deaths, 15 to 19 fewer myocardial infarctions, 9 to 13 fewer stent thrombosis events, 28 to 38 fewer target vessel revascularization events, and 35 to 48 fewer target lesion revascularization events per 1000 people.

CONCLUSIONS

Compared with coronary angiography guided percutaneous coronary intervention, intravascular imaging guided percutaneous coronary intervention was associated with significantly reduced cardiac death and cardiovascular outcomes in patients with coronary artery disease. The estimated absolute effects of intravascular imaging guided percutaneous coronary intervention showed a proportional relation with baseline risk, driven by the severity and complexity of coronary artery disease.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42023433568.

Outcomes With Intravascular Ultrasound and Optical Coherence Tomography Guidance in Percutaneous Coronary Intervention

Intracoronary imaging has become an important tool in the treatment of complex lesions with percutaneous coronary intervention (PCI). This retrospective cohort study identified 1,118,475 patients with PCI from the Nationwide Readmissions Database from 2017 to 2019. Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) were identified with appropriate International Classification of Diseases, Tenth Revision codes. The primary outcome was major adverse cardiac events. The secondary outcomes include net adverse clinical events (NACEs), all-cause mortality, myocardial infarction (MI) readmission, admission for stroke, and emergency revascularization. The multivariate Cox proportional hazard regression was used to adjust for demographic and co-morbid confounders. Of 1,118,475 PCIs, 86,140 (7.7%) used IVUS guidance and 5,617 (0.5%) used OCT guidance. The median follow-up time was 184 days. The primary outcome of major adverse cardiac events was significantly lower for the IVUS (6.5% vs 7.6%; hazard ratio [HR] 0.89, 95% confidence interval [CI] 0.86 to 0.91, p <0.001) and OCT (4.4% vs 7.6%; HR 0.69, 95% CI 0.61 to 0.79, p <0.001) groups. IVUS was associated with significantly lower rates of NACEs (8.4% vs 9.4%; HR 0.92, 95% CI 0.89 to 0.94, p <0.001), all-cause mortality (3.5% vs 4.3%; HR 0.85, 95% CI 0.82 to 0.88, p <0.001), readmission for MI (2.7% vs 3.0%; HR 0.95, 95% CI 0.91 to 0.99, p = 0.012), and admission for stroke (0.5% vs 0.6%; HR 0.86, 95% CI 0.78 to 0.95, p = 0.002). OCT was associated with significantly lower rates of NACEs (6.6% vs 9.4%; HR 0.81, 95% CI 0.73 to 0.89, p <0.001) and all-cause mortality (1.8% vs 4.3%; HR 0.51, 95% CI 0.42 to 0.63, p <0.001). Emergency revascularization was not significantly different with IVUS guidance. Readmission for MI, stroke, and emergency revascularization were not significantly different with OCT guidance. A subgroup analysis of patients with ST-elevation MI and non-ST-elevation MI showed similar results. In conclusion, the use of IVUS and OCT guidance with PCI were associated with significantly lower rates of morbidity and mortality in real-world practice.

Assessment of Repeat Revascularization in Percutaneous Coronary Intervention Randomized Controlled Trials as a Surrogate for Mortality: A Meta-Regression Analysis

The association of repeat revascularization after percutaneous coronary intervention (PCI) with mortality is uncertain. To assess the association of repeat revascularization after PCI with mortality in patients with coronary artery disease (CAD). We identified randomized controlled trials comparing PCI with coronary artery bypass graft (CABG) or optimal medical therapy (OMT) using electronic databases through January 1, 2022. We performed a random-effects meta-regression between repeat revascularization rates after PCI (absolute risk difference [%] between PCI and CABG or OMT) with the relative risks (RR) of mortality. We assessed surrogacy of repeat revascularization for mortality using the coefficient of determination (R2), with threshold of 0.80. In 33 trials (21,735 patients), at median follow-up of 4 (2-7) years, repeat revascularization was higher after PCI than CABG [RR: 2.45 (95% confidence interval, 1.99-3.03)], but lower vs OMT [RR: 0.64 (0.46-0.88)]. Overall, meta-regression showed that repeat revascularization rates after PCI had no significant association with all-cause mortality [RR: 1.01 (0.99-1.02); R2=0.10) or cardiovascular mortality [RR: 1.01 (CI: 0.99-1.03); R2=0.09]. In PCI vs CABG (R2=0.0) or PCI vs OMT trials (R2=0.28), repeat revascularization did not meet the threshold for surrogacy for all-cause or cardiovascular mortality (R2=0.0). We observed concordant results for subgroup analyses (enrollment time, follow-up, sample size, risk of bias, stent types, and coronary artery disease), and multivariable analysis adjusted for demographics, comorbidities, risk of bias, MI, and follow-up duration. In summary, this meta-regression did not establish repeat revascularization after PCI as a surrogate for all-cause or cardiovascular mortality.

Impact of adherence to the hybrid algorithm for initial crossing strategy selection in chronic total occlusion percutaneous coronary intervention

INTRODUCTION AND OBJECTIVES

The hybrid algorithm was designed to assist with initial and subsequent crossing strategy selection in chronic total occlusion (CTO) percutaneous coronary interventions (PCIs). However, the success of the initially selected strategy has received limited study.

METHODS

We examined the impact of adherence to the hybrid algorithm recommendation for initial CTO crossing technique selection in 4178 CTO PCIs from a large multicenter registry.

RESULTS

The initial crossing strategy was concordant with the hybrid algorithm recommendation in 1833 interventions (44%). Patients in the concordant group had a similar age to those in the discordant group but a lower mean J-CTO score (2.0 ± 1.4 vs 2.8 ± 1.1; P < .01). The concordant group showed higher technical success with the first crossing strategy (68% vs 48%; P < .01) and higher overall technical success (88% vs 83%; P < .01) with no difference in the incidence of in-hospital major adverse events (1.8% vs 2.3%; P = .26). In multivariable analysis, after adjustment for age, prior myocardial infarction, prior PCI, prior coronary artery bypass grafting, J-CTO score, and scheduled CTO PCI, nonadherence to the hybrid algorithm was independently associated with lower technical success of the initial crossing strategy (odds ratio, 0.55; 95% confidence interval, 0.48-0.64; P < .01).

CONCLUSIONS

Adherence to the hybrid algorithm for initial crossing strategy selection is associated with higher CTO PCI success but similar in-hospital major adverse cardiac events.

First bilateral lobar lung transplant in Ireland: advanced operative strategies in lung transplantation

Lobar lung transplantation is an option that provides the possibility of transplantation of small size recipients with size-mismatch donor lungs by surgically reducing the size of donor lungs. We report our first experience of bilateral lobar lung transplantation of big donor lungs, in a small size urgently listed recipient, after size reduction. A 24 years old girl with end stage cystic fibrosis received the bilateral lobar lung transplant. She made very good recovery postoperatively and was discharged home two weeks following surgery.

Peroneal artery pseudoaneurysm after surgical stabilisation of a Weber C trimalleolar ankle fracture: A case report and review of literature

A case of post-traumatic pseudoaneurysm of the peroneal artery is presented. This occurred after standard open reduction and internal fixation of a Weber type C trimalleolar fracture of the left ankle in a 33-year-old man. The pseudoaneurysm was diagnosed 12 weeks post-operatively when the patient attended the pre-assessment clinic for the removal of the syndesmosis screw. Diagnosis was confirmed on ultrasonography, and the anatomical site was confirmed by a digital subtraction angiogram. The pseudoaneurysm was coiled successfully, and the syndesmosis screw was removed in theatre the next day, without any post-operative complications. We explore the aetiology of post-traumatic peroneal pseudoaneurysms, with emphasis on the pathoanatomy and management as described in literature. This is a rare complication, but is easily manageable provided an index of suspicion is maintained.

Evaluation and modification of existing CETP

For the development of small and medium scale industries in various Gujarat industrial development corporation (GIDC) areas and in clusters of industrial areas, the common effluent treatment plant (CETP) has always been found advantageous in view of cost of treatment, operation and maintenance and disposal of residues being produced. In small scale industrial units due to market requirement, product changes and quantity enhancement are taking place. Due to such changes, the effluent characteristics are continuously changing which affects performance of CETP. Hence it has been found necessary to study continuously the performance, evaluation and modification in the working of the CETP. This paper contains a case study of one of the existing CETP near Baroda which is facing the problem of disposal of treated effluent in which the important parameters like COD, BOD, Suspended Solid, NH3-N and oil and grease were analyzed. Based on the characterization of wastewater, the various treatability studies were carried out on CETP wastewater. To comply with disposal standard prescribed by Effluent Channel Project Ltd.(ECPL)* and Gujarat Pollution Control Board (GPCB) for discharge of industrial effluent into channel, various treatments in form of ammonia stripping, coagulation and flocculation, biological treatment, filtration and chlorination are suggested.

Mathematical approach for the assessment of similarity factor using a new scheme for calculating weight

The objective of the present work was to propose a method for calculating weight in the Moore and Flanner Equation. The percentage coefficient of variation in reference and test formulations at each time point was considered for calculating weight. The literature reported data are used to demonstrate applicability of the method. The advantages and applications of new approach are narrated. The results show a drop in the value of similarity factor as compared to the approach proposed in earlier work. The scientists who need high accuracy in calculation may use this approach.

Posterior capsule opacification in eyes with steroid-induced cataracts: Comparison of early results

PURPOSE

To evaluate posterior capsule opacification (PCO) development after cataract surgery in eyes with or without a history of steroid use.

SETTING

Iladevi Cataract & IOL Research Centre, Ahmedabad, India.

DESIGN

Comparative case series.

METHODS

This study comprised consecutive patients with a history of steroid intake (oral, inhaled, injectable, or topical) for at least 4 months who developed posterior subcapsular cataract (PSC) (study group) and patients without a history of steroid intake with uncomplicated PSC (control group). Standardized surgery was performed in both groups. Digital retroillumination photographic documentation was performed 1 month and 1 year postoperatively. The digital images were analyzed for PCO using Evaluation of Posterior Capsule Opacification (EPCO) software; the entire intraocular lens (IOL) optic and the central 3.0 mm optic area were evaluated. The EPCO score and EPCO area were determined.

RESULTS

One year postoperatively, the mean EPCO score was statistically significantly higher in the study group (n = 30) than in the control group (n = 60) (0.33 ± 0.37 [SD] versus 0.15 ± 0.26), as was the mean EPCO area (0.323 ± 0.36 versus 0.15 ± 0.26) (both P<.04). Within the central 3.0 mm optic area, the mean EPCO scores (0.149 ± 0.309 versus 0.003 ± 0.016 P<.04) and mean EPCO area values (0.149 ± 0.309 versus 0.003 ± 0.016) were statistically significantly higher in the study group (P<.04).

CONCLUSION

Steroid-induced PSC was associated with a higher risk for PCO after cataract surgery at the 1-year follow-up.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Single coronary artery; extremely rare coronary anomaly successfully treated surgically in young adult male

Single coronary artery arising from aortic root, is a rare congenital anomaly. A 30-year-old male presented with acute myocardial infarction (MI) complaining of chest pain and raised troponin levels. Emergency angiography showed no coronary lesions but both left and right coronary arteries arising from single ostium. Patient was operated electively and perioperative findings confirmed the diagnosis of single coronary artery, as left coronary artery after taking origin from right sinus of valsalva runs through the septum, before dividing into left anterior descending and circumflex branches. The single coronary ostium opened with a slit like incision over the course of left main coronary, making the size of ostium three to four times bigger than the native one. In addition left internal mammary artery was harvested and grafted to the left anterior descending branch distally. Patient made successful recovery. Four months follow up dobutamine stress echo showed no inducible ischemia.

CSF biomarkers of Alzheimer disease in HIV-associated neurologic disease

BACKGROUND

HIV-associated neurologic disorders (HAND) continue to develop in many patients with HIV. CSF amyloid measurements in HAND have been reported to be similar to those in dementia of the Alzheimer type (DAT). Confirmatory evaluation of this finding in carefully evaluated subjects is needed.

METHODS

CSF specimens were obtained from subjects clinically categorized with normal cognition from the general population, HIV+ subjects with normal cognition, HIV+ subjects with impaired cognition, or presumed HIV- subjects with mild DAT. CSF measurements of beta-amyloid((1-42)) (Abeta42), beta-amyloid((1-40)) (Abeta40), total tau (t-tau), and phosphorylated tau (p-tau181) were performed.

RESULTS

CSF Abeta42 measured in 49 HAND subjects had a median level of 501 pg/mL, which was lower than that of 50 controls of similar age who had median of 686 pg/mL (p < 0.0001) or 21 HIV+ subjects without cognitive impairment who had median of 716 pg/mL (p < 0.003). HAND subjects had similar CSF Abeta42 to 68 subjects with mild DAT. There was no difference of CSF Abeta40 between the groups. Tau and p-tau181 was elevated in DAT, but slightly lower than control in both HIV+ groups.

CONCLUSIONS

beta-Amyloid((1-42)) (Abeta42) measurements in CSF of cognitively impaired patients with HIV are similar to those in patients with mild dementia of the Alzheimer type (DAT). Normal or slightly depressed CSF tau and p-tau181 measurements distinguish these patients with HIV-associated neurologic disorders (HAND) from patients with DAT. Further evaluation of amyloid metabolism in patients with HIV cognitive disorder is needed to understand the implications of depressed CSF Abeta42 in the setting of HAND.

Duration of action of intravitreal ranibizumab and bevacizumab in exudative AMD eyes based on macular volume measurements

BACKGROUND/AIMS

Sequential macular volume and central foveal point thickness (CFPT) measurements on optical coherence tomography (OCT) were used to determine the efficacy and duration of action of ranibizumab versus bevacizumab in wet age-related macular degeneration (AMD).

METHODS

Retrospective chart review of patients who received their first treatment of intravitreal ranibizumab or bevacizumab for exudative AMD. 316 patients (202 ranibizumab;114 bevacizumab) who received 823 injections (313 ranibizumab;510 bevacizumab) were identified. 74 patients had pre- and post-treatment OCTs performed to determine CFPT and macular volume changes.

RESULTS

Ranibizumab caused a significant reduction in CFPT (278 (SD 84) before treatment vs 227 (80) microm after treatment; p = 0.001) and macular volume (7.22 (0.96) vs 6.69 (0.74) mm(3); p = 0.002). Intravitreal bevacizumab caused a similar reduction in CFPT (288 (94) vs 220 (55) microm; p = 0.008) and macular volume (7.36 (1.08) vs 6.50 (0.42) mm(3); p<0.001). The mean duration of action was 74.0 (19.1) days for ranibizumab compared with 101.8 (16.6) days for bevacizumab (p = 0.036; t test). The ratio of the relative duration of action of bevacizumab versus ranibizumab was 1.40 (0.19).

CONCLUSIONS

Both drugs are equally effective at reducing CFPT or macular volume. Bevacizumab appears to take longer to achieve the minimum macular volume, and its effects take longer to wear off, suggesting it can be given less often.

Posterior capsule opacification after extra capsular cataract extraction in Indian rural population: foldable acrylic vs poly (methyl-methacrylate) intraocular lenses a randomized clinical trial

PURPOSE

To compare the performance of single-piece acrylic vspoly (methylmethacrylate) intraocular lenses (IOL) on the development of posterior capsule opacification (PCO) after conventional extra capsular cataract extraction (ECCE).

MATERIALS AND METHODS

One hundred and eighty-two eyes of 91 patients with bilateral senile cataract undergoing ECCE were prospectively randomized to receive a single-piece Alcon AcrySof SA60AT IOL or a single-piece EPOCH polymethylmethacrylate IOL in the first eye to have surgery. At 1, 6 and 12 months post-operative follow-up, digital retro illumination images of the posterior capsule were taken for PCO assessment semi-objectively using PCO (POCO automated analysis software) system. Relationship of anterior capsule contact (total off and partial cover) on optic for PCO was analyzed.

RESULTS

The AcrySof IOL was associated with less PCO than EPOCH lens at 6 months (10.01+/-8.75% vs 32.26+/-27.44%; P<0.001) and 1-year (11.65+/-10.55% vs 38.38+/-29.62%; P<0.001) follow-up. The EPOCH IOL showed a remarkably significant difference on development of PCO with anterior capsule overlap on IOL optic (total off and part on) 1 year (P<0.039), whereas no such difference was observed with the AcrySof IOL (P=0.197).

CONCLUSION

The AcrySof IOL led to significantly less PCO than the EPOCH IOL post-operatively after extracapsular cataract extraction.

Interinstitutional and intrainstitutional transmission of a strain of Acinetobacter baumannii detected by molecular analysis: comparison of pulsed-field gel electrophoresis and repetitive sequence-based polymerase chain reaction

Pulsed-field gel electrophoresis and repetitive sequence-based polymerase chain reaction provided comparable strain discrimination with minor discordance in typing Acinetobacter baumannii clinical isolates from patients at our hospital and affiliated institutions. Typing revealed a cluster strain with intrainstitutional and interinstitutional spread during the study period. A long-term acute care facility may have been the reservoir.

Management of congenital bilateral subluxated cataract with Cionni ring

Use of Cionni ring helped in the successful intraocular lens (IOL) implantation in a 30-year-old patient with bilateral congenital subluxated cataracts. The IOL was stable, well-centered without any iridodonesis or pseudophakodonesis.

Local Anaesthetic Flush Reduces Postoperative Pain and Haematoma Formation After Great Saphenous Vein Stripping—A Randomised Controlled Trial

OBJECTIVES

To observe the effect of local anaesthetic flush through the great saphenous vein (GSV) tunnel on postoperative pain and haematoma formation following saphenous vein stripping operations.

DESIGN

Prospective, double-blind, randomised, control trial.

METHODS

One hundred patients were randomized to receive 20 ml of local anaesthetic (bupivacaine 0.25% + adrenaline) or saline control flush through the GSV tunnel after stripping in a double-blind study. Visual analogue pain scores were used to measure postoperative pain daily for the 1st week, then at 3 weeks and 6 weeks. Patients were examined during the 1st, 3rd and 6th week for haematoma formation.

RESULTS

In the control group the median postoperative pain score was 4 (range 0-7) in the immediate postoperative period compared to a median of 1 (range 0-4) in the LA group (p<0.001). The median pain score on day-4 was 4 (range 1-6) (control) vs. 1 (range 0-3) (LA group) (p<0.001, Mann-Whitney Utest) and on day-6 it was 1 (range 0-5) (control) vs. 0 (range 0-5) (LA group) (p<0.001, Mann-Whitney). Twelve patients (24%) developed a haematoma in the GSV tunnel in the control group compared to three patients (6%) in the LA group (p = 0.007).

CONCLUSION

Flushing of the GSV tunnel with bupivacaine plus adrenaline significantly reduces postoperative pain and haematoma formation in patients undergoing GSV stripping for varicose veins.

Double-blind, randomised, controlled trial assessing controller medications in asthma

BACKGROUND

The motive behind conducting this study was to determine if better control of asthma can be achieved by adding a second controller medication and to assess its use to reduce the dose of inhaled steroids.

OBJECTIVES

The study aimed to determine whether either oral sustained-release theophylline or montelukast added to inhaled steroids improved clinical symptoms and pulmonary function test parameters when compared to high-dose steroids alone.

METHODS

Ninety patients with incompletely controlled asthma were allocated, in a randomised, double-blind fashion, to one of three treatment groups: group A: double dose of inhaled budesonide (400 microg b.i.d.), group B: 400 mg oral sustained-release theophylline plus budesonide (200 microg b.i.d.) and group C: 10 mg montelukast plus budesonide (200 microg b.i.d.). The primary endpoints were forced expiratory volume in 1 s (FEV(1)) and mean morning peak expiratory flow rate (PEFR).

RESULTS

All three groups had improved FEV(1) and PEFR at 8 weeks (p < 0.001). Group C increased their PEFR by 18.7 l/min (95% confidence interval, CI, 12.4-25.1) more than group A and by 19.8 l/min (95% CI 13.4-26.1) more than group B (both p = 0.001). Similarly, group C had a 114 ml (95% CI 45-183 ml) greater improvement in FEV(1) than group A and a 95 ml (95% CI 26-164 ml) greater improvement than group B (both p = 0.01).

CONCLUSIONS

Addition of montelukast to budesonide is safe and results in greater improvement in pulmonary function test parameters than high-dose budesonide treatment or addition of theophylline.

Acute and chronic health effects due to green tobacco exposure in agricultural workers

BACKGROUND

An epidemiological study was undertaken in Gujarat, India to study the acute and chronic health effects of occupational exposure to green tobacco.

METHODS

Non-Flue Cured Virginia (FCV) tobacco is the main crop in many districts of Central Gujarat. Three villages were selected from Anand district for the study and a random sample of 685 exposed workers were examined. Six hundred and fifty-five control workers with the same socio-economic status were examined from two villages where tobacco was not cultivated.

RESULTS

The overall prevalence of green tobacco sickness (GTS) was 47.0% among tobacco workers. The prevalence in women workers was 55.7% while in men workers it was 42.66%. To detect the chronic health effects prevalence of hypertension, electrocardiogram (ECG) abnormalities, and eye problems in all the workers and reproductive abnormalities in women workers, all subjects received a medical examination. The data were compared in exposed and control group but they were non-significant statistically. No case of tobacco amblyopia was detected.

CONCLUSION

The prevalence of GTS among non-FCV tobacco workers is high. However, from viewpoint of severity it can be considered as mild acute nicotine toxicity, which is relieved without medication. No significant difference is observed as regards to chronic health effects among tobacco workers and control workers.

Corneal endothelial safety of intracameral preservative-free 1% xylocaine

PURPOSE

To evaluate the effect of intracameral preservative-free 1% xylocaine on the corneal endothelium as an adjuvant to topical anaesthesia during phacoemulsification and Acrysof foldable IOL implantation.

MATERIAL & METHODS

This is a prospective, controlled, randomised, double-masked study. 106 patients with soft to moderately dense (Grade 1-3) senile cataract and corneal endothelial cell density of >1500/mm2 were randomised to the xylocaine group (n=53) and control group(n=53). Central endothelial specular microscopy and ultrasound corneal pachymetry were performed preoperatively. On the first postoperative day the eyes were evaluated for corneal oedema and Descemet's folds. Ultrasound corneal pachymetry was performed at 1, 3 and 12 months. Specular microscopy was performed at 3 and 12 months. Cell loss was expressed as a percentage of preoperative cell density. Six patients could not complete one year follow-up. Chi-square and paired t test (2 tail) statistical tests were applied for analysis.

RESULTS

Four (7.54%) patients in the xylocaine group and 5 (9.43%) in the control group had a few Descemet's folds associated with mild central stromal oedema. Corneal thickness increased from 549.3micro +/- 37.2micro to 555.5micro +/- 36.5micro in the xylocaine group and from 553.1micro +/- 36.2micro to 559.3micro +/- 40.5micro in the control group at the one-month postoperative visit. Thickness returned to the preoperative level in xylocaine group 549.6micro +/- 34.5micro and control group 554.7micro +/- 41.1micro at three months. (P=0.484) The percentage of cell loss was 4.47 +/- 2.53% in the xylocaine group and 4.49 +/- 3.09% in the control group at one year. (P=0.97)

CONCLUSION

Intracameral preservative-free 1% xylocaine does not appear to affect corneal endothelium adversely during phacoemulsification.

Study of drug resistance in previously treated tuberculosis patients in Gujarat, India

SETTING

Department of Tuberculosis and Chest Diseases and State Tuberculosis Diagnosis and Training Centre (STDTC), a DOTS centre in Ahmedabad, Gujarat State, India. The study was carried out by retrospectively reviewing patient data between January 2000 and August 2001.

OBJECTIVE

To evaluate the pattern of drug resistance among previously treated tuberculosis patients who remained symptomatic or smear-positive despite receiving anti-tuberculosis drugs under DOTS for a minimum of 5 months.

DESIGN

A total of 1472 pulmonary tuberculosis patients who had taken anti-tuberculosis treatment were evaluated retrospectively with respect to their drug resistance pattern by sputum culture for acid-fast bacilli (AFB) and sensitivity testing with isoniazid, rifampicin, streptomycin and ethambutol (E).

RESULT

Of the 1472 patients evaluated, 804 (54.6%) were treatment failure cases and 668 (45.4%) were relapse cases; 822 patients (373 failure and 449 relapse) were culture-positive. Of these 822 patients, 482 (58.64%, 261 failure and 221 relapse) were resistant to one or more drugs. Resistance to one drug was observed in 86 patients (10.46%), to two drugs in 149 (18.13%), to three drugs in 122 (14.84%) and to four drugs in 125 (15.21%). Single drug resistance was most commonly seen with isoniazid (62 patients, 7.5%), followed by streptomycin (12 patients, 1.4%), rifampicin (eight patients, 0.97%) and ethambutol (four patients, 0.4%). Resistance to isoniazid plus rifampicin alone was seen in 76 patients (9.2%).

CONCLUSION

Drug resistance is a major problem in the treatment of pulmonary tuberculosis. Detection of drug resistance patterns and treatment with second-line anti-tuberculosis drugs in appropriate regimens are necessary in the treatment of failure and relapse cases in order to reduce the emergence of multidrug-resistant tuberculosis.

Considerations of anthropometric, tissue volume, and tissue mass scaling for improved patient specificity of skeletal S values

It is generally acknowledged that reference man (70 kg in mass and 170 cm in height) does not adequately represent the stature and physical dimensions of many patients undergoing radionuclide therapy, and thus scaling of radionuclide S values is required for patient specificity. For electron and beta sources uniformly distributed within internal organs, the mean dose from self-irradiation is noted to scale inversely with organ mass, provided no escape of electron energy occurs at the organ boundaries. In the skeleton, this same scaling approach is further assumed to be correct for marrow dosimetry; nevertheless, difficulties in quantitative assessments of marrow mass in specific skeletal regions of the patient make this approach difficult to implement clinically. Instead, scaling of marrow dose is achieved using various anthropometric parameters that presumably scale in the same proportion. In this study, recently developed three-dimensional macrostructural transport models of the femoral head and humeral epiphysis in three individuals (51-year male, 82-year female, and 86-year female) are used to test the abilities of different anthropometric parameters (total body mass, body surface area, etc.) to properly scale radionuclide S values from reference man models. The radionuclides considered are 33P, 177Lu, 153Sm, 186Re, 89Sr, 166Ho, 32P, 188Re, and 90Y localized in either the active marrow or endosteal tissues of the bone trabeculae. S value scaling is additionally conducted in which the 51-year male subject is assigned as the reference individual; scaling parameters are then expanded to include tissue volumes and masses for both active marrow and skeletal spongiosa. The study concludes that, while no single anthropometric parameter emerges as a consistent scaler of reference man S values, lean body mass is indicated as an optimal scaler when the reference S values are based on 3D transport techniques. Furthermore, very exact patient-specific scaling of radionuclide S values can be achieved if measurements of spongiosa volume and marrow volume fraction (high-resolution CT with image segmentation) are known in both the patient and the reference individual at skeletal sites for which dose estimates are sought. However, the study indicates that measurements of the spongiosa volume alone may be sufficient for reasonable patient-specific scaling of S values for the majority of radionuclides of interest in internal-emitter therapy.

Cerebral protection by hypoxic preconditioning in a murine model of focal ischemia-reperfusion

Sublethal periods of hypoxia or ischemia can induce adaptive mechanisms to protect against subsequent lethal ischemic insults in a process known as ischemic preconditioning. In the present study, we developed a murine model of cerebral preconditioning using several common strains of adult mice. Animals were exposed to sublethal hypoxia (11% oxygen for 2 h) 48 h prior to a 90 min period of transient focal middle cerebral artery occlusion, induced by an intraluminal filament; injury was assessed 24 h later by TTC staining. Infarct volume in hypoxia-preconditioned animals was reduced 46%, 58%, and 64% in C57Bl/6, 129SvEv, and Swiss-Webster ND4 mice relative to their respective untreated controls. This non-invasive murine model of ischemic tolerance should be useful for elucidating the molecular basis of this protection using transgenic and knockout mice.

Basic science of articular cartilage repair

As the ability to understand the peculiarities of successful healing of articular cartilage defects moves forward, it becomes clear that this complex orthopaedic problem soon will be successfully addressed. A multidisciplinary approach, combining clinical experience, cogent biomaterial designs, new cell biologic processes, biomechanical assessment, and modern molecular biology, clearly is leading toward clinically acceptable, viable, and consistent articular cartilage regeneration.

BDNF protects against spatial memory deficits following neonatal hypoxia-ischemia

Hypoxic-ischemic (H-I) brain injury in the human perinatal period often leads to significant long-term neurobehavioral dysfunction in the cognitive and sensory-motor domains. Using a neonatal H-I injury model (unilateral carotid ligation followed by hypoxia) in postnatal day seven rats, previous studies have shown that neurotrophins, such as brain-derived neurotrophic factor (BDNF), can be protective against neural tissue loss. The present study explored potential relationships between neural protective and behavioral protective strategies in this neonatal H-I model by determining if neonatal H-I was associated with behavioral spatial learning and memory deficits and whether the neurotrophin BDNF was protective against both brain injury and spatial learning/memory dysfunction. Postnatal day seven rats received vehicle or BDNF pretreatments (intracerebroventricular injections) followed by H-I or sham treatments and then tested for spatial learning and memory on the simple place task in the Morris water maze from postnatal days 20 to 30, and their brains were histologically analyzed at 4 weeks following treatments. H-I rats with vehicle pretreatment displayed significant tissue loss in the hippocampus (including CA1 neurons), cortex, and striatum, as well as severe spatial memory deficits (e.g., short probe times). BDNF pretreatment resulted in significant protection against both H-I-induced brain tissue losses and spatial memory impairments. These findings indicate that unilateral H-I brain injury in a neonatal rodent model is associated with cognitive deficits, and that BDNF pretreatment is protective against both brain injury and spatial memory impairment.

Assessment of acute right ventricular dysfunction induced by right coronary artery occlusion using echocardiographic atrioventricular plane displacement

Right ventricular (RV) systolic function analysis by echocardiography has traditionally required RV endocardial border definition with subsequent tracing and is often inaccurate or impossible in technically poor studies. The atrioventricular plane displacement (AVPD) method attempts to use the descent of the tricuspid annular ring, a reflection of the longitudinal shortening of the right ventricle, as a surrogate marker for RV systolic function. We hypothesized that RV ischemia induced during right coronary artery occlusion proximal to the major right ventricular branches would result in severe right ventricular systolic dysfunction detectable by the AVPD method. During this pilot study, seven patients undergoing elective proximal RCA angioplasty had echocardiographic measurement of RV AVPD performed at baseline (i.e., immediately prior to RCA balloon inflation), during the last 30 seconds of first RCA balloon inflation, and at 1 minute after balloon deflation (recovery). Lateral and medial RV AVPD were significantly reduced from baseline values during intracoronary balloon inflation. (Lateral: 2.45 cm +/- 0.22 vs 1.77 cm +/- 0.13, P < 0.001; medial: 1.46 cm +/- 0.37 vs 1.28 cm +/- 0.32, P < 0.05). Additionally, lateral and medial RV AVPD significantly returned towards baseline values during recovery. (Lateral: 2.39 cm +/- 0.20, P < 0.001; medial: 1.58 cm +/- 0.27, P = 0.01). At baseline, all lateral RV AVPD values were > 2.0 cm, whereas during balloon inflation all were < 2.0 cm. No such clear distinction was found in medial RV AVPD values. Proximal RCA angioplasty is associated with a significant reduction in lateral and medial RV AVPD. Thus RV AVPD may serve as a marker for RV systolic dysfunction.

BDNF blocks caspase-3 activation in neonatal hypoxia-ischemia

Hypoxic-ischemic (H-I) injury to the brain in the perinatal period often leads to significant long-term neurological deficits. In a model of neonatal H-I injury in postnatal day 7 rats, our previous data have shown that cell death with features of apoptosis is prominent between 6 and 24 h after H-I and that neurotrophins, particularly BDNF, can markedly protect against tissue loss. During brain development, caspase-3 is required for normal levels of programmed cell death. Utilizing an antibody specific for the activated form of caspase-3, CM1, we now show that caspase-3 is specifically activated in neuronal cell bodies and their processes beginning at 6 h and peaking 24 h following unilateral carotid ligation and exposure to hypoxia in postnatal day 7 rats. Caspase-3 activation began to occur in cortex at 6 h and in striatum and hippocampus at 12-18 h. Caspase-3 activation was also observed in developing oligodendrocytes. Intracerebroventricular injection of BDNF prior to H-I injury almost completely abolished evidence of H-I-induced caspase-3 activation in vivo. Utilizing a specific molecular marker of an apoptotic pathway, these findings demonstrate that H-I injury to the developing brain is a strong apoptotic stimulus leading to caspase-3 activation, that BDNF can block this process in vivo, and that the ability of BDNF to inhibit caspase activation and subsequent apoptosis likely accounts in large part for its protection against neuronal injury in this model.

Systemic and mucosal immunity is elicited after both intramuscular and intravaginal delivery of human immunodeficiency virus type 1 DNA plasmid vaccines to pregnant chimpanzees

DNA vaccines encoding human immunodeficiency virus type 1 (HIV-1) env/rev and gag/pol were delivered intravaginally (IVAG) and intramuscularly (IM) to 2 pregnant chimpanzees. Vaccination was well tolerated and each chimpanzee developed antibodies (up to 1 year later) to both vaccines. Placental transfer of anti-Env and anti-Gag IgG was demonstrated in both maternal/infant pairs. Specific IgG was also demonstrated in saliva, vaginal, and rectal washes after IVAG immunization. Predominantly anti-HIV-1 IgA was detected in the milk of both mothers after both IM and IVAG immunization. Cellular responses included Gag-specific proliferation of lymphocytes and cytotoxic T lymphocytes against both antigens. These data suggest a strategy for induction of mucosal and systemic responses after both IM and IVAG delivery of DNA vaccines in a primate model and could ultimately be useful in lowering maternal-to-fetal transmission of HIV-1, perinatally and through breastfeeding.

Ototoxicity resulting from combined administration of metronidazole and gentamicin

HYPOTHESIS

The hypothesis that metronidazole can augment the ototoxicity of gentamicin was tested.

BACKGROUND

Metronidazole and gentamicin are antibiotics that are used in combination to provide broad-spectrum antimicrobial coverage. It has been observed clinically that an increased ototoxic effect occurs when these agents are used in combination.

METHODS

Groups of guinea pigs were given various doses of gentamicin alone, various doses of gentamicin in combination with metronidazole, or metronidazole alone. Auditory damage was determined electrophysiologically by measurement of the compound action potential. Hair cell damage was quantified by immunofluorescent microscopy.

RESULTS

Electrophysiologic data revealed an augmented ototoxic effect when metronidazole was given with both a moderate and a high dose of gentamicin. Thresholds (dB SPLp) for the compound action potential (N1) for animals receiving a medium dose of gentamicin alone (50 mg/kg) were approximately 20-dB SPLp. This threshold increased to approximately 50-dB SPLp when metronidazole (35 mg/kg) was administered along with the medium-dose gentamicin. Additionally, animals receiving high-dose gentamicin (75 mg/kg) alone demonstrated increased N1 thresholds from 85 to 95 when metronidazole (35 mg/kg) was added to the gentamicin regimen. This effect was evident histopathologically by increased cochlear hair cell damage. Outer hair cell loss for animals receiving medium-dose gentamicin alone did not differ from that of controls. When metronidazole (35 mg/kg) was combined, however, outer hair cell loss increased to approximately 50%.

CONCLUSIONS

These data support the clinical observation of augmented ototoxicity in patients receiving combined gentamicin and metronidazole. Caution should be used when administering these two agents together. Clinicians should consider other antibiotic strategies whenever possible.

Nitric oxide mediates cerebral ischemic tolerance in a neonatal rat model of hypoxic preconditioning

Neuroprotection against cerebral ischemia can be realized if the brain is preconditioned by previous exposure to a brief period of sublethal ischemia. The present study was undertaken to test the hypothesis that nitric oxide (NO) produced from the neuronal isoform of NO synthase (NOS) serves as a necessary signal for establishing an ischemia-tolerant state in brain. A newborn rat model of hypoxic preconditioning was used, wherein exposure to sublethal hypoxia (8% oxygen) for 3 hours renders postnatal day (PND) 6 animals completely resistant to a cerebral hypoxic-ischemic insult imposed 24 hours later. Postnatal day 6 animals were treated 0.5 hour before preconditioning hypoxia with the nonselective NOS inhibitor L-nitroarginine (2 mg/kg intraperitoneally). This treatment, which resulted in a 67 to 81% inhibition of calcium-dependent constitutive NOS activity 0.5 to 3.5 hours after its administration, completely blocked preconditioning-induced protection. However, administration of the neuronal NOS inhibitor 7-nitroindazole (40 mg/kg intraperitoneally) before preconditioning hypoxia, which decreased constitutive brain NOS activity by 58 to 81%, was without effect on preconditioning-induced cerebroprotection, as was pretreatment with the inducible NOS inhibitor aminoguanidine (400 mg/kg intraperitoneally). The protective effects of preconditioning were also not blocked by treating animals with competitive [3-(2-carboxypiperazin-4-yl)propyl-1-phosphonate; 5 mg/kg intraperitoneally] or noncompetitive (MK-801; 1 mg/kg intraperitoneally) N-methyl-D-aspartate receptor antagonists prior to preconditioning hypoxia. These findings indicate that NO production and activity are critical to the induction of ischemic tolerance in this model. However, the results argue against the involvement of the neuronal NOS isoform, activated secondary to a hypoxia-induced stimulation of N-methyl-D-aspartate receptors, and against the involvement of the inducible NOS isoform, but rather suggest that NO produced by the endothelial NOS isoform is required to mediate this profound protective effect.

Modulation of basal and postischemic leukocyte-endothelial adherence by nitric oxide

BACKGROUND AND PURPOSE

Recent studies indicate that leukocytes are important contributors to secondary vascular and parenchymal injury after cerebral ischemia. The present study was undertaken to define nitric oxide (NO)-based mechanisms that regulate leukocyte-endothelial interactions in the cerebral vasculature, how these mechanisms are affected by cerebral ischemia, and whether NO-based therapies can affect postischemic leukocyte dynamics.

METHODS

Leukocyte adherence to pial venules of anesthetized newborn piglets was quantified by in situ fluorescence videomicroscopy through closed cranial windows during basal conditions and during reperfusion after 9 minutes of asphyxia. Nitric oxide synthase (NOS) was inhibited by local window superfusion of L-nitroarginine; superfusion of sodium nitroprusside was used to donate NO.

RESULTS

Local inhibition of NOS under resting conditions increased leukocyte-endothelial adherence 2.2-fold and 3.9-fold over baseline values after 1 hour and 2 hours, respectively; this response was completely blocked by cosuperfusion with L-arginine. Cosuperfusion of superoxide dismutase reversed L-nitroarginine-induced leukocyte adherence by 89% and 63% at these respective time points. The extent of acute leukocyte adherence elicited by NOS inhibition was similar in magnitude to that observed during the initial 2 hours of reperfusion after asphyxia. Leukocyte adherence was not additionally increased in asphyxic animals treated with L-nitroarginine. Sodium nitroprusside robustly inhibited asphyxia-induced leukocyte adherence back to control levels.

CONCLUSIONS

NO exerts a tonic antiadherent effect in the cerebral microcirculation by inactivation of adherence-promoting superoxide radical formation. Cerebral ischemia is associated with an inhibition of NOS or lower levels of NO, which results in leukocyte-endothelial adherence that can be prevented by NO donors. The latter may be useful therapeutically to prevent the purported vascular and parenchymal dysfunction and injury caused by activated leukocytes in ischemic brain.

Determinants of aerobic and anaerobic exercise performance in cystic fibrosis

We examined aerobic and anaerobic exercise performance in 17 subjects with cystic fibrosis (CF) (age 25+/-10 [SD] yr; 47% females; FEV1 62+/-21% pred) and 17 age- and sex-matched control subjects (age 25+/-8 [SD] yr; 41% females; FEV1 112+/-15% pred) in relation to pulmonary function and nutritional status. Aerobic capacity was determined as maximal oxygen consumption (VO2max) (ml/kg/min) and anaerobic threshold (AT; ml VO2/kg/min) from a graded exercise stress test on an electronically braked bicycle ergometer. Anaerobic performance was assessed from the average work of two bouts of pedaling to exhaustion at a load corresponding to 130% Vo2max from graded exercise. Both aerobic and anaerobic performances were decreased in subjects with CF (p < 0.001). The duration of anaerobic exercise in subjects with CF was similar to control subjects. In control subjects, pulmonary function did not correlate to aerobic or anaerobic exercise. In subjects with CF significant relationships between FEV1, vital capacity, and FEF25-75% to AT were found, suggesting the pulmonary limitation to aerobic capacity. In both patients with CF and control subjects, lean body mass and arm muscle area significantly correlated with anaerobic performance but not with VO2max or AT. We conclude that nutritional status, rather than pulmonary function, is the major determinant of anaerobic exercise capacity in CF. The preserved duration of anaerobic exercise at equivalent workloads (corresponding to 130% of VO2max from graded exercise) suggests that readily available energy stores in muscle may be similar in CF and normal individuals.

Xanthine oxidase-derived superoxide causes reoxygenation injury of ischemic cerebral endothelial cells

Oxygen free radicals, generated by cerebral ischemia, have been widely implicated in the damage of vascular endothelium. Endothelial cells have been proposed as a significant source of oxygen free radicals. In the present study, we developed an anoxia-reoxygenation (AX/RO) model using pure cultures of cerebral endothelial cells (CECs) isolated from piglet cortex to measure CEC oxygen free radical production and determine its role in AX/RO-induced CEC injury. CEC injury, as measured by lactate dehydrogenase efflux into the culture medium, increased progressively with the duration of anoxic exposure, becoming significant after 10 h. Reoxygenation significantly increased CEC anoxic injury in a time-dependent manner. A 55% increase in oxygen free radical production, determined by fluorescence detection of dihydroethidium oxidation, was measured at the end of 4-h reoxygenation in CECs subjected to AX/RO conditions that killed 40% of the cells. Blockade of oxygen free radical production with superoxide dismutase (SOD; 250 and 1000 U/ml) or oxypurinol (50 and 200 microM), a potent xanthine oxidase inhibitor, reduced this injury by 32-36% and 30-39%, respectively. Results from our in vitro model indicate that CECs produce significant amounts of oxygen free radicals following ischemia, primarily from the xanthine oxidase pathway. These radicals ultimately have a cytotoxic effect on the very cells that produced them. Thus, reductions in oxygen free radical-mediated vascular injury may contribute to improvements in neurophysiologic outcome following treatment with oxygen free radical inhibitors and scavengers.

Effect of supplemental oxygen on supramaximal exercise performance and recovery in cystic fibrosis

The effects of supplemental O2 on recovery from supramaximal exercise and subsequent performance remain unknown. If recovery from exercise could be enhanced in individuals with chronic lung disease, subsequent supramaximal exercise performance could also be improved. Recovery from supramaximal exercise and subsequent supramaximal exercise performance were assessed after 10 min of breathing 100% O2 or room air (RA) in 17 cystic fibrosis (CF) patients [25 +/- 10 (SD) yr old, 53% men, forced expired volume in 1 s = 62 +/- 21% predicted] and 17 normal subjects (25 +/- 8 yr old, 59% men, forced expired volume in 1 s = 112 +/- 15% predicted). Supramaximal performance was assessed as the work of sustained bicycling at a load of 130% of the maximum load achieved during a graded maximal exercise. Peak minute ventilation (VE) and heart rate (HR) were lower in CF patients at the end of each supramaximal bout than in controls. In CF patients, single-exponential time decay constants indicated faster recovery of HR (tau HR = 86 +/- 8 and 73 +/- 6 s in RA and O2, respectively, P < 0.01). Similarly, fast and slow time constants of two-exponential equations providing the best fit for ventilatory recovery were improved in CF patients during O2 breathing (tau 1VE = 132.1 +/- 10.5 vs. 82.5 +/- 10.4 s; tau 2VE = 880.3 +/- 300.1 vs. 368.6 +/- 107.1 s, P < 0.01). However, no such improvements occurred in controls. Supramaximal performance after O2 improved in CF patients (109 +/- 6% of the 1st bout after O2 vs. 94 +/- 6% in RA, P < 0.01). O2 supplementation had no effect on subsequent performance in controls (97 +/- 3% in O2 vs. 93 +/- 3% in RA). We conclude that supplemental O2 after a short bout of supramaximal exercise accelerates recovery and preserves subsequent supramaximal performance in patients with CF.

Marked age-dependent neuroprotection by brain-derived neurotrophic factor against neonatal hypoxic-ischemic brain injury

Hypoxic-ischemic brain injury in survivors of perinatal asphyxia is a frequently encountered clinical problem for which there is currently no effective therapy. Neurotrophins, such as brain-derived neurotrophic factor (BDNF), can protect responsive neurons against cell death in some injury paradigms. While the role of BDNF in hypoxic-ischemic brain injury is not clear, evidence suggests that BDNF may have different effects in the developing, as opposed to the adult, brain. We found that a single intracerebroventricular (ICV) injection of BDNF resulted in rapid and robust phosphorylation of trk receptors in multiple brain regions in the postnatal day (PD) 7 rat brain. BDNF also markedly protected against hypoxic-ischemic brain injury at PD7. It protected against 90% of tissue loss due to hypoxic-ischemia when given just prior to the insult and against 50% of tissue loss when give after the insult. In contrast, ICV injection of BDNF in PD21 and adult rats resulted in little trk phosphorylation and less dramatic protection against unilateral hypoxic-ischemic injury at PD21. Because of its potent neuroprotective actions in the developing brain, BDNF may be a potential treatment for asphyxia and other forms of acute injury in the perinatal period.

KATP channels mediate adenosine-induced hyperemia in retina

PURPOSE

The authors and others have shown previously that the purine nucleoside adenosine is a potent vasodilator in the retinal microcirculation, mediating increases in retinal blood flow (RBF) in response to several autoregulatory stimuli. The current experiments were undertaken to elucidate the involvement of adenosine triphosphate (ATP)-sensitive potassium (KATP) channels and the adenylate cyclase--cyclic adenosine monophosphate (cAMP) second-messenger system in the transduction of adenosine's hyperemic response.

METHODS

Retinal fluorescein angiograms were videorecorded in isoflurane-anesthetized newborn pigs, and changes in arteriovenous transit times and retinal arteriolar and venular diameters were used to estimate stimulus-induced changes in RBF.

RESULTS

Intravitreal perivascular microsuffusion of 5 nmol and 50 nmol adenosine caused dose-dependent increases in RBF of 79% +/- 4% (P < 0.05; n = 5) and 323% +/- 61% (P < 0.05; n = 5), respectively. The KATP channel antagonist glibenclamide (0.5 nmol and 5 nmol) caused a significant, dose-dependent attenuation of the hyperemic response to 5 nmol adenosine. The specificity of glibenclamide for blocking KATP channels was demonstrated by its ability to block by 94% +/- 6% (P < 0.05; n = 5) the increase in RBF (94% +/- 7%; P < 0.05) elicited by the intravitreal microsuffusion of the KATP channel agonist cromakalim (5 nmol), whereas it had no effect on the 103% +/- 12% increase in RBF (P < 0.05; n = 5) induced by the nitric oxide donor sodium nitroprusside (15 nmol). Adenosine-induced hyperemia was not potentiated by forskolin (1.7 nmol; n = 4), an adenylate cyclase activator, and was not attenuated by dideoxyadenosine (5 nmol; n = 4), an adenylate cyclase inhibitor. In addition, no significant increases in RBF could be elicited by 2.5 to 25 nmol 8-bromo-cAMP (n = 4), a membrane-permeable cAMP analog.

CONCLUSIONS

These results in the piglet indicate that adenosine increases blood flow in the retina by activating KATP channels, not by increasing in cyclic AMP secondary to adenylate cyclase activation. They also underscore the potential importance of KATP channels in the transduction of retinal vasodilatative responses to other agonists.

Adenosine transport inhibition ameliorates postischemic hypoperfusion in pigs

Cerebral ischemia is often followed by a period of delayed hypoperfusion that may contribute to tissue injury. We tested the hypothesis that augmentation of interstitial adenosine can improve tissue perfusion under this condition 10 min global ischemia was produced in two groups of isoflurane-anesthetized newborn pigs by occlusion of subclavian and brachiocephalic arteries, and changes in local cortical blood flow and cortical interstitial purine metabolites were measured using the combined hydrogen clearance-microdialysis technique. In one group, the dialysis probe was perfused with artificial cerebrospinal fluid buffer containing nitrobenzyl-thioinosine (NBT1, 100 mumol/l), a competitive inhibitor of adenosine transport. In the untreated group (n = 9), baseline cortical blood flow (39 +/- 3 ml/min/100 g) was depressed by 51 +/- 5% and 42 +/- 6% at 40 and 60 min, respectively, of postischemic reperfusion. NBTI increased baseline interstitial adenosine levels 2.4-fold which increased baseline cortical blood flow 1.5-fold to 60 +/- 4 ml/min/100 g, and increased both absolute adenosine levels as well as adenosine as a percentage of total purine metabolites throughout ischemia and reperfusion. As a result, the extent of postischemic hypoperfusion was significantly lessened in NBTI-treated animals (n = 9), with reductions in cortical blood flow of only 28 +/- 3% and 24 +/- 5% at 40 and 60 min of reperfusion, respectively. These results indicate that inhibition of adenosine transport by NBTI elevates interstitial adenosine concentration during and following cerebral ischemia, and concomitantly improves cortical perfusion in the post-ischemic period. The latter effect may contribute to the documented neuroprotective efficacy of adenosinergic therapy in cerebral ischemia.

Reduction in cerebral ischemic injury in the newborn rat by potentiation of endogenous adenosine

Because of ontogenic influences on the pathophysiologic mechanisms of brain injury in the perinatal brain, and in particular, the incomplete development of adenosine receptor systems, we investigated the potential for adenosine to provide cerebro-protection in a well established newborn rat model of hypoxia-ischemia. Fifteen litters of postnatal d 7 animals were subjected to unilateral carotid ligation and exposure to hypoxia (8% oxygen) for 3 h. Immediately after hypoxia-ischemia, animals received either the adenosine deaminase inhibitor deoxycoformycin (DCF; 2.5 mg/kg intraperitoneally) or the adenosine uptake inhibitor propentofylline (PPF; 10 mg/kg intraperitoneally); paired littermates received an equivalent volume of normal saline. On postnatal d 14, injury or protection was assessed by differences in hemispheric weights, morphometric determinations of infarct area, and histopathologic analyses. DCF resulted in a 34% (p = 0.02) and 31% (p = 0.03) reduction in hemispheric weight disparities and infarct area, respectively; for PPF, these reductions were 46% (p = 0.03) and 32% (p = 0.04), respectively. Light microscopic examinations of striatum, thalamus, hippocampus, and cortex revealed that both drugs significantly improved histologic scores as well. Measurements in six separate litters indicated that neither drug significantly reduced core body temperature for at least 6 h postadministration. These findings indicate that potentiation of endogenous adenosine levels in the perinatal brain can significantly ameliorate brain injury. Each of these treatment strategies was effective even when administered after the hypoxic-ischemic insult. Thus, further investigations of adenosinergic therapies are warranted in this and other perinatal models of cerebral ischemia to elucidate in detail their potential for clinical application.

Hypoglycemia selectively abolishes hypoxic reactivity of pial arterioles in piglets: role of adenosine

Episodes of hypoxia often occur in hypoglycemic newborns, but it is not known whether dysfunctions in cerebrovascular regulation contribute to brain injury incurred by these affected neonates. We tested the hypotheses that 1) perinatal hypoglycemia impairs cerebrovascular responses to hypoxia and 2) a reduced vascular smooth muscle sensitivity to adenosine accounts for this impairment. Responses of 25- to 50-mu m-diam pial arterioles were determined using the cranial window technique in isoflurane-anesthetized newborn piglets < 5 days of age. Hypoxia (arterial PO2 = 28 +/- 1 mmHg) caused a 47 +/- 5% increase (P = 0.0008) in arteriolar diameter, 89% of which could be blocked by prior superfusion of the window space with the preferential A2-adenosine receptor antagonist 3,7-dimethyl-1-propargylxanthine (DMPX; 50 microM). Insulin-induced hypoglycemia (blood glucose = 18 +/- 1 mg/dl without isoelectric electroencephalogram) caused a 31 +/- 5% increase (P = 0.002) in arteriolar diameter; however, no additional dilatative response to hypoxia (arterial PO2 = 28 +/- 1 mmHg) could be elicited in these animals. Arteriolar dilation of 41 +/- 6% (P = 0.002) induced by superfusion of 20 microM adenosine under normoglycemic conditions was also completely abolished after the animals were rendered hypoglycemic. Unlike the response to hypoxia and adenosine, hypoglycemia only attenuated prostanoid-dependent dilations to hypercapnia (arterial PCO2 = 68 +/- 3 mmHg) by 55 +/- 9%. These results indicate that, in the newborn, hypoglycemia selectively abolishes hypoxic reactivity through an impairment in adenosine-mediated cerebrovascular dilation.

Effect of hypoglycemia on postischemic cortical blood flow, hypercapnic reactivity, and interstitial adenosine concentration

Hypoglycemia increases the vulnerability of the perinatal brain to asphyxia, but it is not known if hypoglycemia-induced changes in cerebral hemodynamics and vascular reactivity underlie this vulnerability. This study tested the hypothesis that hypoglycemia exacerbates postischemic hypoperfusion, and impairs postischemic CO2 reactivity. The authors also examined the hypothesis that postischemic hypoperfusion is associated with a reduction in the interstitial concentration of the vasodilator metabolite adenosine. Global cerebral ischemia of 10 minutes duration was induced in newborn pigs anesthetized with isoflurane by occlusion of subclavian and brachiocephalic arteries; cortical cerebral blood flow (CBF) and interstitial adenosine concentration were evaluated simultaneously using the combined hydrogen clearance/microdialysis technique. Hypoglycemia (blood glucose < 25 mg/dl) was induced by regular insulin (25 IU/kg) administered intravenously 2 hours prior to induction of ischemia. In the eight normoglycemic animals, baseline CBF was 38 +/- 4 ml/min/100 gm and baseline adenosine concentration was 1.2 +/- 0.1 microM; in the eight hypoglycemic animals, these values were 39% (p < 0.05) and 62% (p < 0.05) greater, respectively, under baseline conditions. At 1 hour of postischemic reperfusion in normoglycemic animals, CBF was reduced 39% relative to the preischemic baseline (p < 0.01), concomitant with a 27% reduction (p < 0.05) in adenosine concentration, suggesting that this lowered concentration may underlie delayed hypoperfusion. These postischemic reductions in CBF and interstitial adenosine concentration were significantly greater in hypoglycemic animals, with CBF and adenosine concentration reduced 70% (p < 0.001) and 71% (p < 0.01), respectively, relative to baseline. In nine animals preischemic reactivity to hypercapnia was unaffected by hypoglycemia. Postischemic hypercapnic reactivity was retained in the eight normoglycemic animals, but was attenuated 73% (p < 0.05) in hypoglycemic animals. Thus, in the newborn pig, hypoglycemia exacerbates postischemic cortical hypoperfusion and impairs postischemic cerebrovascular reactivity to hypercapnia.

A novel capillary collection method for obtaining current glycosylated haemoglobin levels in diabetic children

A simple method for collecting capillary blood for measurement of glycosylated haemoglobin (HbA1c) was developed that allows samples to be obtained at home and then mailed to the laboratory 2 weeks before a hospital visit. A single drop of blood is collected into a 2 ml plastic tube and sent for HbA1c assay on the Diamat HPLC system which has inter- and intra-assay coefficients of variation < 2.6 and < 1.2%, respectively. Results of simultaneously obtained venous and capillary samples in 32 diabetic children agreed well with each other. A separate study of 25 patients was performed to determine whether transport conditions affected the samples. Posted samples were compared with venous samples; again the values were in good agreement. This method is now used routinely in the diabetic clinic. Its value was determined by questionnaire in 40 children with age range 4-17 years. No family experienced difficulty collecting samples and all samples received were suitable for analysis. Children preferred this method to blood collection in the clinic as they felt it was less traumatic and more convenient. Seventy-nine percent of them understood its value in the long-term control of diabetes. In 40.5% of visits changes to management were made at the clinic due to the availability of the results.

Neuroprotection from ischemic brain injury by hypoxic preconditioning in the neonatal rat

Very recent studies in adult gerbils and rats have shown that exposure to sublethal ischemia can confer neuroprotection from subsequent lethal ischemic episodes. To determine if a similar phenomenon can be elicited during the perinatal period, we have developed a preconditioning regimen that involves exposure to normothermic hypoxia (8% oxygen) 24 h prior to hypoxia-ischemia in the well-established post-natal-day 7 rat pup model [20]. Significant infarction, manifested as a 34 +/- 4% reduction in cerebral hemispheric weight ipsilateral to the carotid ligation, was noted in control animals (n = 24) one week after hypoxia-ischemia, whereas littermates preconditioned with 3 h hypoxia (n = 29) showed no evidence of hemispheric necrosis. Lack of injury in the latter animals was confirmed at the cellular level by histopathologic analyses of Nissl-stained coronal sections. Thus, pre-exposure to hypoxia induces endogenous adaptive mechanisms that can protect the perinatal brain from hypoxic-ischemic injury.

Case report: computed tomography of generalized lymphangiomatosis and chylothorax

The diagnosis of lymphangiomatosis can often be made on clinical grounds with the aid of plain radiography. In children with intractable chylothorax computed tomography (CT) of the thorax may reveal the presence of a mediastinal mass but frequently in lymphangiomatosis will not demonstrate any specific features. Abdominal CT, on the other hand, may suggest the diagnosis by the association with intraabdominal lymphangioma.

Case report: sustained-release verapamil overdose causing stroke: an unusual complication

A 47-year-old woman ingested 7.2 gm of sustained-release verapamil. She developed hypotension, idioventricular rhythm, mild acidosis, mild hyperglycemia, and aspiration pneumonia that required antibiotics and mechanical ventilatory support. In addition, she had a stroke, which resulted from left cerebral hemispheric damage, an unusual complication. Stroke is reported only once in the literature. Special problems related to slow release medication and the need to be aware of them are discussed.