Effects of meconium aspiration in isolated perfused rat lungs

Our objective was to study meconium-induced lung injury in isolated perfused rat lungs exposed to anoxia. Our working hypothesis was that meconium-induced lung injury is independent of preexisting hypoxia, and that hypoxia will increase severity of lung injury observed after meconium aspiration. We compared five different groups of animals (n = 5) for pulmonary arterial pressure (PAP), weight lung changes, and TNFalpha expression. Group I had lungs instilled with 4 ml of normal saline. Group II had lungs exposed to 5 min of anoxia. Group III had lungs instilled with 4 ml of 30% filtered human meconium. Group IV had lungs exposed to 5 min of anoxia and then instilled with 4 ml of 30% filtered human meconium. Group V had lungs instilled with 4 ml of 30% unfiltered human meconium. Our subjects were adult Sprague-Dawley rats. The isolated rat lung model was prepared according to Levey and Gast (J Appl Physiol 1966;21:313-316). Lungs were ventilated with room air. Anoxia was caused by the use of N(2). The pulmonary artery was cannulated, and pulmonary arterial pressure and lung weight were measured. Lung weight and pulmonary arterial pressure were monitored for 120 min, and TNFalpha levels were measured in effluent at 15, 30, 60, and 120 min. Experiments were done at the Michael Reese Hospital (Chicago, IL). At the end of the experiment, PAP reached its highest values in group V (10.0 +/- 1.7 mmHg). Final PAPs in groups I-IV were: 4.85 +/- 0.3, 4.99 +/- 0.4, 5.93 +/- 0.3, and 7.25 +/- 0.51 mmHg, respectively). Lung wet weight increased significantly only in groups IV and V vs. group I; at 120 min, they were: 0.96 +/- 0.3 g, P < 0.01, and 1.5 g +/- 0.2 g, P < 0.01, respectively. TNFalpha levels did not change significantly over time in group I. TNFalpha is a marker as well as proprietor of pulmonary inflammatory response. TNFalpha reached its highest levels in groups IV and V: 595 and 753 pg/ml at 120 min, respectively. In conclusion, a short episode of anoxia prior to meconium aspiration may increase lung sensitivity to meconium-induced lung injury. This effect may be moderated by the TNFalpha present in the pulmonary circulation.     

Information processing bottlenecks in macaque posterior parietal cortex: an attentional blink?

When two brief stimuli are presented in rapid succession, our ability to attend and recognize the second stimulus is impaired if our attentional resources are devoted to processing the first. Such inability (termed the “attentional blink” in human studies) arises around 200–500 ms following the onset of the first stimulus. We trained two monkeys on a delayed-match-to-sample task where both the location and orientation of two successively presented grating patches had to be matched. When the delay between the two gratings was varied, monkey’s behavioral performance (d′) was affected in a way that was analogous to the attentional blink in humans. Furthermore, a subset of neurons in the monkey’s lateral intraparietal area, known to be crucial in the control of attention, closely followed the variation in d′, even on occasions when d′ followed an atypical pattern. Our results provide the first behavioral demonstration of an attentional bottleneck in the macaque of a type similar to the human attentional blink as well as a possible single-neuron correlate of the phenomenon.     

Prevalence of facet joint pain in chronic low back pain in postsurgical patients by controlled comparative local anesthetic blocks

OBJECTIVE: To evaluate the prevalence of facet joint pain in patients with chronic low back pain (CLBP) after surgical intervention(s). DESIGN: A prospective, nonrandomized, consecutive study. SETTING: An ambulatory interventional pain management setting. PARTICIPANTS: The prevalence of facet joint pain was evaluated in patients with CLBP after various surgical intervention(s) referred to an interventional pain management practice. The sample was derived from 282 patients with persistent CLBP after various surgical intervention(s). Of these, 242 patients consented to undergo interventional techniques. A total of 117 consecutive patients with chronic, nonspecific low back pain, after lumbar surgical intervention(s) were evaluated with controlled, comparative local anesthetic blocks. INTERVENTIONS: Controlled, comparative local anesthetic blocks (1% lidocaine or 1% lidocaine followed by .25% bupivacaine) under fluoroscopic visualization using 0.5mL to block each facet joint nerve. MAIN OUTCOME MEASURES: A positive response was defined as at least 80% reduction of pain with ability to perform previously painful movements. A positive response was considered to be pain relief from the lidocaine block lasting at least 1 hour or at least 2 hours or greater than duration of relief with lidocaine when bupivacaine was used. Controlled, comparative local anesthetic blocks were used to eliminate false-positive results. Valid information is only obtained by performing controlled blocks in the form of comparative local anesthetic blocks, in which, on 2 separate occasions, the same joint is anesthetized by using local anesthetics with different durations of action. If patients obtained appropriate response with both blocks, they were considered a positive. If they obtained appropriate response with lidocaine but not with bupivacaine, they were considered false-positive, whereas if the response was negative with lidocaine, they were considered negative. RESULTS: The prevalence of lumbar facet joint pain in patients with recurrent pain after various surgical intervention(s) was 16% (95% confidence interval, 9%-23%). The false-positive rate with a single block with lidocaine was 49%. CONCLUSIONS: Facet joints are clinically important pain generators in a small but significant proportion of patients with recurrent CLBP after various surgical intervention(s).     

A novel site-II directed glycoprotein estimation ELISA to aid rabies vaccine manufacture for veterinary and human use

Although the World Health Organization recommends the use of in vitro techniques to qualify rabies vaccine lot release, very limited proposals have been made to arrive at a harmonized approach for wide scale usage. The present study proposed and evaluated the use of a novel avidin–biotin ELISA as an alternative to these in vivo tests in rabies vaccine manufacture. This assay utilized a neutralizing pan reactive monoclonal antibody (mAb) reactive with the conserved site-II of the natively folded rabies glycoprotein. Linear regression analysis of the in vitro glycoprotein estimates with the in vivo potency values, showed a good correlation (r² = 0.8) with veterinary vaccines, but a poor correlation (r² = 0.2) with human vaccines. However, we could qualitatively arrive at cut-off glycoprotein estimates from the ELISA, above which all the vaccines were declared to be protective by mouse challenge studies (>2.5 IU/dose).     

Serum protein profile studies of cervical cancers in monitoring of tumor response to radiotherapy using HPLC-LIF: A pilot study

ObjectiveExploration of the feasibility of serum protein profiles for monitoring tumor radioresponse in cervical cancers using HPLC-LIF system.Materials and methodsTwenty-one subjects were recruited in the study. Out of them 7 were healthy, 14 were cervical cancer patients who undertook fractionated radiotherapy (RT) with 2 Gy per fraction over 25 fractions, for 5 weeks followed by 2 applications of intracavitary brachytherapy once a week.Blood collected from above subjects was processed to obtain serum. Serum chromatograms of ‘normal’ (n=7) and conspicuous probes before RT (n=14, ‘malignant’) and 24 h after second fraction of RT (n=13, ‘2-RT’), were recorded using an In-house-built HPLC-LIF set-up. Data were analyzed in two approaches: (1) classical method using relative intensities of selected peaks, (2) principal component analysis (PCA).Clinical assessment of tumor radioresponse was carried out 4 months after first fraction of RT and the degree of the tumor shrinkage was determined as an index of radioresponsiveness (complete response (CR): 100% shrinkage, partial response (PR): ≥50% shrinkage, and no response (NR): ≤50% shrinkage) which was further correlated with the analysis of 2-RT serum chromatograms.ResultsNormal vs. malignant chromatograms demonstrated pronounced differences in the 800–1800 s region. Malignant vs. 2-RT chromatograms showed minute variations in the 1300–1800 s region. Our analysis, in both of the approaches, produced clear differentiation between ‘normal’ and ‘malignant’, whereas differentiation between ‘malignant’ and ‘2-RT’ was minimal. Clinical evaluation of the tumor radioresponse yielded that out of 13 patients (one patient discontinued the radiotherapy) ten showed CR, two showed PR and one NR. In case of prediction of tumor radioresponse, analysis of the 2-RT chromatograms produced only minor differentiation among CR, PR and NR groups.ConclusionProtein profiling of serum samples differentiated ‘normal’ from ‘malignant’, but could not differentiate ‘malignant’ from ‘2-RT’. Also this technique has limited application in prediction of tumor radioresponse.     

Surfactant replacement therapy: clinical and experimental studies

Surfactant replacement therapy has been investigated extensively both in animal models and clinical studies. Although not yet available for routine clinical treatment, surfactant replacement in HMD holds great promise. This article reviews the current literature in this area.     

Pulmonary surfactant replacement in respiratory distress syndrome

Exogenous surfactant therapy in infants with HMD leads to dramatic improvement in oxygenation and disease course. Both prophylactic and rescue treatments have shown a significant reduction in morbidity and mortality from the disease. There are several questions yet to be answered regarding the most effective surfactant, the appropriate time of treatment, and the appropriate dose, as well as the number of treatments required. Based on the available data, surfactant TA has shown promising and consistent results. Another important question to be answered is the role of surfactant in milder cases of HMD and its impact on the cost of hospitalization. Hopefully, future studies will be able to provide answers to these questions.     

SUCKING IN THE NEWBORN INFANT DURING THE FIRST HOUR OF LIFE

The sucking response was studied in 13 low-birth-weight (LBW) newborns and 17 normal-birth-weight (NBW) newborns. An electronic suckometer was used to measure maximum intensity pressure for the suction and expression components of the sucking response for four consecutive 15 sec intervals at 5, 15, 30, 45, and 60 min of life. At these times LBW newborns exerted mean suction pressures of 5.8, 8.7, 3.1, 7.8, and 9.3 mm Hg and mean expression pressures of 14.0, 11.9, 13.0, 8.5, and 5.0 mm Hg. NBW newborns exerted mean suction pressures of 2.1, 25.0, 34.0, 68.2, and 93.7 mm Hg and mean expression pressures of 4.6, 5.6, 7.3, 8.3, and 7.0 mm Hg. Positive correlations were found for both LBW and NBW infants between suction pressure and birth weight (p < 0.01) and gestational age (p < 0.01); for NBW infants between maternal parity and suction pressure at 5 min (p < 0.05); and for LBW infants between second stage of labor and expression pressure at 5 min (p < 0.05). No significant differences were found in sucking pressures based on race, sex, maternal medication, or the occurrence of prenatal, intrapartal, or neonatal complications. The results of this investigation demonstrate that the sucking response is present in most newborn infants, LBW as well as NBW infants, during the first hour of life. These data also suggest a relationship between the sucking ability of newborn infants and both crying and sucking experience.     

Persistent embryonic veins in the arteriovenous malformation of the diencephalon

The diencephalic arteriovenous malformation is produced by the posterior cerebral, posterior choroidal, and anterior choroidal arteries. The abnormal arterialised vessels seen in these malformation represent dorsal and ventral diencephalic veins. The drainage of the shunted blood is primarily into the transverse sinus. This is later diverted medially into the great cerebral vein, with the formation of the basal vein. The medial drainage, in keeping with the normal developmental pattern, is seen frequently. The presence and locations of angiomas are very variable and do not follow any predictable pattern.