kV-CBCT-Guided Daily Adaptation Improves Target Coverage and Spares Normal Tissue for Accelerated Partial Breast Irradiation

PURPOSE/OBJECTIVE(S)

Linear accelerator based accelerated partial breast irradiation (APBI) in early-stage breast cancer necessitates a reduction in non-target breast tissue to decrease long term toxicity and adverse cosmetic outcome. In particular, lumpectomy cavity seromas may decrease in size and deform in shape during the course of short course APBI. Online adaptive RT (oART) offers considerable prospect for treating mobile targets through pendulous breast anatomy. However, there are limited studies outlining the methods and outcomes of CBCT-based oART for APBI. Here we present a retrospective, single institutional study analyzing the treatment process for patients receiving stereotactic kV-CBCT guided oART APBI.

MATERIALS/METHODS

Fourteen patients were treated to 30 Gy in 5 fractions for a total of 70 fractions. Time between simulation and treatment, change in gross tumor volume (GTV), and differences in DVH metrics with adaption were analyzed. The Wilcoxon paired, non-parametric test was utilized to test for DVH metric differences between the scheduled plans (initial plans recalculated on daily CBCT anatomy) and treated plans, which were either the scheduled or adapted plan (initial plans re-optimized using daily anatomy), depending on the preference of the treating physician or physicist.

RESULTS

Median (inter-quartile range) time from simulation to first treatment was 28 days (21-33 days). During this same time, GTV volume reduced to 72.5% (57.8-87.3%) of the simulation lumpectomy cavity volume. Adaptive treatments required 31.1 min (27.2-37.1 min) from start of CBCT to treatment session end. Table 1 summarizes differences between scheduled and treated plan metrics for 70 fractions, 62 (89%) of which were treated adaptively and 8 (11%) of which were treated using the scheduled plan. Significant improvement in prescription planning target volume coverage (p = 0.003), significant reduction in 5/6 organ-at-risk metrics evaluated (p ≤ 0.003), and significant improvement in conformity index and high dose spillage (p ≤ 0.001) were realized with adaption. Table 1: Scheduled versus treated plan metrics.

CONCLUSION

APBI using oART decreased most organs at risk DVH metrics, improved plan quality metrics, and increased target coverage, justifying the use of kV-CBCT-guided oART for APBI.

Reporting bias in imaging: higher accuracy is linked to faster publication

OBJECTIVES

The objective of this study was to evaluate whether higher reported accuracy estimates are associated with shorter time to publication among imaging diagnostic accuracy studies.

METHODS

We included primary imaging diagnostic accuracy studies, included in meta-analyses from systematic reviews published in 2015. For each primary study, we extracted accuracy estimates, participant recruitment periods and publication dates. Our primary outcome was the association between Youden's index (sensitivity + specificity - 1, a single measure of diagnostic accuracy) and time to publication.

RESULTS

We included 55 systematic reviews and 781 primary studies. Study completion dates were missing for 238 (30%) studies. The median time from completion to publication in the remaining 543 studies was 20 months (IQR 14-29). Youden's index was negatively correlated with time from completion to publication (rho = -0.11, p = 0.009). This association remained significant in multivariable Cox regression analyses after adjusting for seven study characteristics: hazard ratio of publication was 1.09 (95% CI 1.03-1.16, p = 0.004) per unit increase for logit-transformed estimates of Youden's index. When dichotomizing Youden's index by a median split, time from completion to publication was 20 months (IQR 13-33) for studies with a Youden's index below the median, and 19 months (14-27) for studies with a Youden's index above the median (p = 0.104).

CONCLUSION

Imaging diagnostic accuracy studies with higher accuracy estimates were weakly associated with a shorter time to publication.

KEY POINTS

• Higher accuracy estimates are weakly associated with shorter time to publication. • Lag in time to publication remained significant in multivariate Cox regression analyses. • No correlation between accuracy and time from submission to publication was identified.

TRPM4 inhibitor 9-phenanthrol activates endothelial cell intermediate conductance calcium-activated potassium channels in rat isolated mesenteric artery

BACKGROUND AND PURPOSE

Smooth muscle transient receptor potential melastatin 4 (TRPM4) channels play a fundamental role in the development of the myogenic arterial constriction that is necessary for blood flow autoregulation. As TRPM4 channels are present throughout the vasculature, we investigated their potential role in non-myogenic resistance arteries using the TRPM4 inhibitor 9-phenanthrol.

EXPERIMENTAL APPROACH

Pressure and wire myography were used to assess the reactivity of rat arteries, the latter in combination with measurements of smooth muscle membrane potential. Immunohistochemistry (IHC) and endothelial cell (EC) calcium changes were assessed in pressurized vessels and patch clamp measurements made in isolated ECs.

KEY RESULTS

The TRPM4 inhibitor 9-phenanthrol reversibly hyperpolarized mesenteric arteries to circa EK and blocked α1 -adrenoceptor-mediated vasoconstriction. Hyperpolarization was abolished and vasoconstriction re-established by damaging the endothelium. In mesenteric and cerebral artery smooth muscle, 9-phenanthrol hyperpolarization was effectively blocked by the KCa 3.1 inhibitor TRAM-34. 9-Phenanthrol did not increase mesenteric EC [Ca(2+)]i , and Na(+) substitution with N-methyl-D-glucamine only increased the muscle resting potential by 10 mV. Immunolabelling for TRPM4 was restricted to the endothelium and perivascular tissue.

CONCLUSIONS AND IMPLICATIONS

These data reveal a previously unrecognized action of the TRPM4 inhibitor 9-phenanthrol - the ability to act as an activator of EC KCa 3.1 channels. They do not indicate a functionally important role for TRPM4 channels in the reactivity of non-myogenic mesenteric arteries.

Concentration of Mycobacterium tuberculosis from sputum using ligand-coated magnetic beads

SETTING

Direct sputum smear microscopy is usually less sensitive than the indirect approach using concentration by centrifugation, but laboratories often do not have access to appropriate equipment. An alternative method of sample concentration has been developed based on magnetic beads coated with a polymeric ligand that binds mycobacteria species. The 'TB-Beads' technology allows manual sample preparation using simple magnetic separation equipment prior to microscopy.

OBJECTIVE

1) To evaluate TB-Beads, in combination with fluorescent auramine staining, on a blind panel of 129 frozen samples from the Special Programme for Research & Training in Tropical Diseases (TDR), the World Health Organization sputum bank; and 2) to compare the microscopy results to indirect microscopy, culture and the clinical data already available on these samples.

RESULTS

The correlation between the TB-Beads protocol and indirect microscopy was 96.1% (124/129). The TB-Beads protocol was 89.4% (76/85) sensitive compared to culture and 77.8% (77/99) sensitive compared to clinical diagnosis.

CONCLUSION

Capture by magnetic particles yields a concentrated sample that is immobilised over a defined area of the slide, thereby aiding microscopic analysis. TB-Beads allow laboratories that currently perform comparatively insensitive direct microscopy to implement a concentration method that has the potential to improve TB detection rates.

Glucose metabolism and insulin secretion in a patient with ABCC8 mutation and Fanconi-Bickel syndrome caused by maternal isodisomy of chromosome 3

Fanconi-Bickel syndrome (FBS) is a rare disorder of glucose transport caused by autosomal recessive mutations in GLUT2. Clinically, FBS results in growth failure, hepatomegaly, renal Fanconi syndrome, and abnormal glucose homeostasis. We report a 23 month old female with FBS characterized by more severe and refractory hypoglycemia than typically seen in this disorder. Although previous reports indicate that FBS patients have diminished insulin secretion, our patient showed evidence of hyperinsulinism (HI). Sequence analysis showed that the patient was homozygous for a known null mutation in GLUT2, confirming the clinical diagnosis of FBS. Parental genotyping showed that the mother was heterozygous for the GLUT2 mutation, while the father was wild type. Tandem repeat marker analysis showed that the patient inherited the GLUT2 mutation via maternal isodisomy of chromosome 3. Further molecular testing showed that the patient was heterozygous for a mutation in ABCC8, a known cause of congenital HI. We discuss the patient's biochemical responses in light of the molecular findings.

Emergency department follow-up of bereaved relatives: an audit of one particular service

BACKGROUND

Although much has been written about the treatment of bereaved relatives in emergency departments, very little has been published about their follow-up after they have left the department.

METHODS

One model of follow-up is described, in which relatives are invited to a meeting in the department 4-6 weeks after their loss. In this model, it is emphasised that the follow-up is not a counselling session but an opportunity to ask questions, and an audit of the service is presented.

RESULTS AND CONCLUSION

It is suggested that the provision of information is theoretically beneficial to the bereavement process.

The influence of previous exposure to environmental mycobacteria on the interferon-gamma response to bacille Calmette-Guérin vaccination in southern England and northern Malawi

We report a large study of the effect of BCG vaccination on the in vitro 6-day whole blood interferon-gamma (IFN-gamma) response to antigens from eight species of mycobacteria among schoolchildren in south-eastern England, where bacille Calmette-Guérin (BCG) vaccination is highly protective against pulmonary tuberculosis, and among young adults in northern Malawi, where BCG vaccination is not protective. In the UK children, BCG induced an appreciable increase in IFN-gamma response to antigens from most species of mycobacteria. The degree of change was linked to the relatedness of the species to Mycobacterium bovis BCG, and provides further evidence of the cross-reactivity of mycobacterial species in priming of the immune system. IFN-gamma responses to purified protein derivatives (PPDs) from M. tuberculosis and environmental mycobacteria were more prevalent in the Malawian than the UK group prior to vaccination; BCG vaccination increased the prevalence of responses to these PPDs in the UK group to a level similar to that in Malawi. There was no evidence that the vaccine-induced change in IFN-gamma response was dependent upon the magnitude of the initial response of the individual to environmental mycobacteria in the United Kingdom or in Malawi. These observations should assist the development and interpretation of human clinical trials of new vaccines against M. tuberculosis in areas of both low and high exposure to environmental mycobacteria.

Dominantly inherited hyperinsulinaemic hypoglycaemia

Congenital hyperinsulinism (HI), the most important cause of hypoglycaemia in early infancy, is a heterogeneous disease with two types of histological lesions, focal and diffuse, with major consequences in terms of surgical approaches. In contrast to focal islet-cell hyperplasia, always sporadic to our knowledge, diffuse hyperinsulinism is a heterogeneous disorder involving several genes, various mechanisms of pathogenic mutations and different transmissions: (i) channelopathy involving the genes encoding the sulphonylurea receptor (SUR1) or the inward-rectifying potassium channel (Kir6.2) in recessively inherited HI or more rarely dominantly inherited HI; (ii) metabolic disorders implicating the short-chain L-3-hydroxyacyl-CoA dehydrogenase (SCHAD) enzyme inrecessively inherited HI, the glucokinase gene (GK), the glutamate dehydrogenase gene (GLUD1) when hyperammonemia is associated, dominant exercise-induced HI with still-unknown mechanism, and more recently the human insulin receptor gene in dominantly inherited hyperinsulinism. Thus, dominant HI disorders always correspond to diffuse HI, where most hypoglycaemia occur in infancy, and are sensitive to medical treatment. Channel causes could be due to dominant negative mutation with one abnormality in channels composed of four Kir6.2 subunits and four SUR1 subunits, leading to a complete destruction of the channel structure or function, or due to haploinsufficiency with only one functional allele, leading to 50% of functional protein, which is not sufficient to obtain enough opened channels to maintain the membrane depolarized. Metabolic causes are due to a gain of function of enzyme activity (deregulated enzymes), except for physical exercise-induced hyperinsulinaemic hypoglycaemia, of still-unknown cause. Congenital hyperinsulinism (HI) is the most important cause of hypoglycaemia in early infancy (Aynsley-Green et al 2000; Cornblath et al 1990; Pagliara et al 1973; Thomas et al 1977). The inappropriate oversecretion of insulin is responsible for profound hypoglycaemia that requires aggressive treatment to prevent severe and irreversible brain damage (Volpe 1995). HI is a heterogeneous disease associated with several genes, various mechanisms of pathogenic mutations and different transmissions (Dunne et al 2004).

Glutamate and tachykinin receptors in central sensitization of withdrawal reflexes in the decerebrated rabbit

This study assessed the involvement of NMDA and group I metabotropic glutamate receptors, and tachykinin NK1 and NK3 receptors, in central sensitization of withdrawal reflexes in the decerebrated rabbit. Reflexes evoked in the ankle flexor tibialis anterior and the knee flexor semitendinosus by electrical stimulation at the base of the toes were enhanced for 29-63 min after application of 20% mustard oil to the tips of the toes. Selective antagonists of mGlu1, mGlu5, NMDA and NR2B-subunit-containing NMDA glutamate receptors, as well as NK1, and NK3 receptors, and a non-selective blocker of all tachykinin receptors, were assessed for their effects on the magnitude and duration of the increase in reflexes induced by mustard oil. Dizocilpine, an antagonist of all NMDA receptors (1 mg intrathecal) abolished facilitation of tibialis anterior reflexes and significantly reduced the magnitude and duration of increase of the semitendinosus response. The NR2B-subtype selective antagonist CP-101,606 decreased the magnitude of facilitation of both reflexes but had no effect on duration of enhancement. Selective antagonists for the mGlu1 (CPCCOEt, 1-3 mg intrathecal), mGlu5 (MPEP, 0.2-1 mg intrathecal), NK1 (L-733,060, 0.3 mg intrathecal) or NK3 (SR 142,801, 1 mg kg(-1) i.v.) receptors had no effect on the amplitude or duration of sensitization. However, the non-selective tachykinin receptor blocker ZD-6021 (0.3 mg intrathecal) reduced the amplitude but not the duration of sensitization in the flexor reflexes. Combination of ZD-6021 with CP-101,606 (doses as above) decreased both aspects of the sensitization response. Dizocilpine reduced reflexes evoked from the heel per se, and dizocilpine, CP-101,606 and ZD-6021 reduced arterial blood pressure. Otherwise the drugs used had no effects on baseline variables. The present data confirm the importance of NMDA receptors as a critical part of the process of central sensitization, provide no evidence for a role of metabotropic glutamate receptors, and show that simultaneous blockade of all tachykinin receptors is required to reveal their role in hyperalgesia. The data further indicate that a combined pharmacological approach offers a potential way forward for the development of new antihyperalgesic agents.

Interferon-gamma and skin test responses of schoolchildren in southeast England to purified protein derivatives from Mycobacterium tuberculosis and other species of mycobacteria

The immune responses of schoolchildren in southeast England to Mycobacterium tuberculosis and other species of mycobacteria were studied prior to vaccination with bacille Calmette-Guérin (BCG). Data are presented for tuberculin (Heaf) skin test and interferon-gamma (IFN-gamma) responses to M. tuberculosis purified protein derivative (PPD), and IFN-gamma responses to PPDs from eight other environmental mycobacteria, measured in 424 schoolchildren (13-15 years of age). Responses to M. tuberculosis PPD were detected in 27% of schoolchildren by in vitro IFN-gamma response and in 20% by the Heaf test. IFN-gamma responses were more prevalent to PPDs from species of mycobacteria other than M. tuberculosis, predominantly those of the MAIS complex and M. marinum (45-60% responders). Heaf test and IFN-gamma responses were associated (P<0.001) for M. tuberculosis, MAIS and M. marinum. These findings have implications for appropriate implementation of vaccination against tuberculosis.

Influence of joint position on electromyographic and torque generation during maximal voluntary isometric contractions of the hamstrings and gluteus maximus muscles

STUDY DESIGN

Repeated measures analysis of joint angle effects on hip and knee muscle electromyographic (EMG) activity.

OBJECTIVES

To simultaneously determine angle-dependent changes in maximal voluntary isometric contraction (MVIC) torque and EMG activity during hip extension and knee flexion.

BACKGROUND

Procedures for normalizing EMG data and for determining torque-angle relationships for various joint motions both entail asking subjects to exert an MVIC. The implicit assumption in these paradigms is that magnitude of the EMG response is at a constant, maximum level so that observed angle-dependent variations in torque are due to mechanical factors, such as muscle length and muscle moment arm.

METHODS AND MEASURES

Fifty subjects (25 men and 25 women) participated in this study (age, 23.5 +/- 4.6 y; range, 18-38 y). Subjects performed maximal isometric knee flexion at 4 knee angles and maximal isometric hip extension at 4 hip angles. The dependent variables were normalized root-mean-square EMG and torque. The process for normalizing EMG and torque data consisted of determining the largest mean value for each subject across testing positions for the muscle of interest. That value was designated as corresponding to 100% MVIC, and all other data for that muscle were expressed as a percentage of the MVIC value. Repeated measures was used to determine angle-dependent changes in normalized MVIC-torque and MVIC-EMG values for each muscle group.

RESULTS

Mean torque-angle relationships were generally consistent with previous reports, though considerable intersubject variability was observed. There were significant angle-dependent differences in maximal EMG for both the hamstring and gluteus maximus muscles. Mean percentages of hamstring MVIC-EMG at knee angles of 30 degrees (81 +/- 19) and 60 degrees (82 +/- 22) were greater than at 0 degrees (68 +/- 20) or 90 degrees (74 +/- 20). The mean percentage of gluteus maximus MVIC-EMG at a hip angle of 0 degrees (94 +/- 10) was greater than at 30 degrees (84 +/- 13), 60 degrees (80 +/- 14), or 90 degrees (64 +/- 20), and gluteus maximus maximal voluntary isometric EMG at 90 degrees was less than at all other angles. These differences could not be explained solely by muscle length-dependent effects on EMG amplitude, suggesting that despite instructions for maximal effort, motor unit activation was not maintained at a constant, maximal level throughout the range of motion. The form of the EMG/angle relationships differed markedly from the torque-angle relationships.

CONCLUSIONS

These findings have implications for the use of MVIC-EMG for reference values in EMG normalization procedures and for the interpretation of mechanisms underlying the torque-angle relationships observed in vivo.

Neonatal electroencephalogram does not predict cognitive and academic achievement scores at early school age in survivors of neonatal extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation is an effective rescue treatment for severe cardiorespiratory failure in term or near-term neonates, although a wide range of neurologic sequelae have been noted in a substantial minority of survivors. The objective of the present study was to determine the value of the neonatal electroencephalogram (EEG) for predicting Wechler Preschool and Primary Scale of Intelligence-Revised (WPPSI-R), Wide Range Achievement Test, and Wide Range Assessment of Memory and Language scores at early school age in 66 testable survivors of extracorporeal membrane oxygenation who were not severely brain damaged. Technically satisfactory EEG recordings were obtained at least twice following admission to our nursery and prior to discharge. The EEGs were classified and graded according to standard criteria. The developmental test results of those who had only normal or mildly abnormal neonatal EEGs (group 1, n = 9) were compared with those who had at least one moderately or markedly abnormal recording (group 2, n = 57). School-age test and subtest scores were not statistically significantly worse in group 2 versus group 1 infants. No child in group 1 and five children in group 2 had WPPSI-R Full-Scale IQ scores of less than 70. Of the nine children in group 2 who had at least one markedly abnormal neonatal EEG recording (graded as burst suppression or as electrographic seizure), only two had abnormally low WPPSI-R Full-Scale IQ scores. We conclude that EEG recordings obtained during the neonatal course of neonates treated with extracorporeal membrane oxygenation do not predict cognitive and academic achievement test results in survivors at early school age who were testable and not severely brain damaged.

Hyperinsulinism and hyperammonemia syndrome: report of twelve unrelated patients

Hyperinsulinism and hyperammonemia syndrome has been reported as a cause of moderately severe hyperinsulinism with diffuse involvement of the pancreas. The disorder is caused by gain of function mutations in the GLUD1 gene, resulting in a decreased inhibitory effect of guanosine triphosphate on the glutamate dehydrogenase (GDH) enzyme. Twelve unrelated patients (six males, six females) with hyperinsulinism and hyperammonemia syndrome have been investigated. The phenotypes were clinically heterogeneous, with neonatal and infancy-onset hypoglycemia and variable responsiveness to medical (diazoxide) and dietary (leucine-restricted diet) treatment. Hyperammonemia (90-200 micromol/L, normal <50 micromol/L) was constant and not influenced by oral protein, by protein- and leucine-restricted diet, or by sodium benzoate or N-carbamylglutamate administration. The patients had mean basal GDH activity (18.3 +/- 0.9 nmol/min/mg protein) not different from controls (17.9 +/- 1.8 nmol/min/mg protein) in cultured lymphoblasts. The sensitivity of GDH activity to inhibition by guanosine triphosphate was reduced in all patient lymphoblast cultures (IC(50), or concentrations required for 50% inhibition of GDH activity, ranging from 140 to 580 nM, compared with control IC(50) value of 83 +/- 1.0 nmol/L). The allosteric effect of ADP was within the normal range. The activating effect of leucine on GDH activity varied among the patients, with a significant decrease of sensitivity that was correlated with the negative clinical response to a leucine-restricted diet in plasma glucose levels in four patients. Molecular studies were performed in 11 patients. Heterozygous mutations were localized in the antenna region (four patients in exon 11, two patients in exon 12) as well as in the guanosine triphosphate binding site (two patients in exon 6, two patients in exon 7) of the GLUD1 gene. No mutation has been found in one patient after sequencing the exons 5-13 of the gene.

Sources of error when tracking irrigation fluids during hysteroscopic procedures

STUDY OBJECTIVE

To evaluate the ability of circulating nurses to estimate input and outgo of irrigating fluids used during hysteroscopic procedures in a hospital operating room.

DESIGN

Simulation of intraoperative measurements (Canadian Task Force classification II-1).

SETTING

Operating room. Intervention. Circulating nurses estimated fluid volumes under circumstances simulating actual conditions of hysteroscopic ablative or resection procedures.

MEASUREMENTS AND MAIN RESULTS

Three-liter glycine irrigation bags were overfilled by an average of 2.8% (62-125 ml). Estimates of fluid remaining in partially emptied bags were in error by an average ranging from 4% to 50%/bag (largest error 10-55%, 157-401 ml). Estimates of fluid in kick buckets were in error by an average of 10% to 39% (largest error 22-66%, 232-903 ml). Visual estimates of fluid on the operating room floor were in error by an average of 56% to 67% (largest error 65-81%, 182-840 ml). Estimates of fluid in suction canisters were consistent among nurses. The accuracy of measurements for partially filled suction canisters primarily depended on the accuracy of canister calibration. Volume contained in cascaded suction canisters from an actual surgical procedure was grossly different from rated capacity.

CONCLUSION

Accurate tracking of irrigation fluid during hysteroscopic procedures is difficult. Even with a mechanical measuring system, fluid lost on the floor can introduce sizable errors. Estimation errors can easily and quickly accumulate to clinically significant volumes. Use of an automated mechanical fluid-tracking system with devices to capture fluid lost from the surgical field is recommended.

A new method of evaluating attachment representations in young school-age children: the Manchester Child Attachment Story Task

We describe a new instrument, using a doll-play vignette completion method, which applies concepts and methodologies from infant and adult attachment research to enable identification and detailed classification of internal representations of attachment relationships in young school-age children. Validation of the Manchester Child Attachment Story Task (MCAST) in a normal population (N = 53) shows good interrater reliability and content validity. Patterns of attachment representation identified show stability over time. Comparisons are made with existing methodologies, and potential applications of the instrument and directions for future research are discussed.

The Manchester Child Attachment Story Task: relationship with parental AAI, SAT and child behaviour

The Manchester Attachment Story Task (MCAST) is a new method for eliciting the internal working model (IWM) of attachment representations in children between 5 and 7 years. The instrument is described in the companion paper, 'A New Method of Evaluating Attachment Representations'. This paper reports initial findings on a non-clinical sample comparing the MCAST with concurrent maternal attachment representation, measures of child temperament and behaviour, and concurrent ratings on the Separation Anxiety Test (SAT). Ratings of disorganized attachment on the MCAST show association with Unresolved status on concurrent maternal Adult Attachment Interview (AAI) and with independent teacher ratings of classroom behaviour. Child temperament shows an effect on the style of engagement with the interview but not the attachment ratings. Possible alternative explanations for the phenomena seen are discussed, along with potential applications of the instrument and directions for future research.

Five-year follow-up of neonates with reconstructed right common carotid arteries after extracorporeal membrane oxygenation

OBJECTIVE

Serial Doppler ultrasonography and long-term neurodevelopmental follow-up outcomes were evaluated prospectively in neonates whose right common carotid artery (RCCA) was reconstructed after extracorporeal membrane oxygenation (ECMO).

METHODS

Children with RCCA reconstruction (n = 34) were monitored for 3.5 to 4.5 years by Doppler ultrasonography for arterial patency, and 28 had IQ testing by 5 years. A comparison group consisted of 35 infants who had RCCA ligation after ECMO. Neonatal electroencephalograms and computed tomography/magnetic resonance imaging scans were also compared.

RESULTS

Reconstructions were successful (<50% RCCA stenosis by Doppler ultrasonography) in 26 (76%) of 34 children, 3 (9%) had >/=50% stenosis, and 5 (15%) had occlusion. No significant differences were seen between reconstructed and ligated groups in neonatal complications or ECMO courses. Occurrence of marked neonatal electroencephalographic abnormalities did not differ between groups. Abnormalities on computed tomography/magnetic resonance imaging scans (4 of 31 vs 11 of 29, P =.025) and cerebral palsy (0 of 34 vs 5 of 35, P =.054) were more common in infants with RCCA ligation. No differences were seen in developmental or IQ scores between the 2 groups, and 4 in each group had cognitive handicaps (at least 1 IQ score <70).

CONCLUSIONS

Most RCCA reconstructions remained patent, with 24% showing significant stenosis or occlusion. Compared with a historical control group, patients with RCCA reconstruction had fewer brain scan abnormalities and tended to be less likely to have cerebral palsy. RCCA reconstruction after venoarterial ECMO may improve outcome.

Effects of silica exposure on substance P immunoreactivity and preprotachykinin mRNA expression in trigeminal sensory neurons in Fischer 344 rats

Trigeminal sensory neurons innervate the nasal cavity and may release substance P (SP) upon exposure to inhaled irritants. The purpose of this study was to determine if silica dust, an occupational irritant causing inflammation, activates sensory neurons supplying the nasal cavity. Male Fischer 344 rats were placed in inhalation chambers and exposed daily to 2 mg/m3 of fresh silica (average diameter 1 microm) for 6 mo. Following exposure, the trigeminal ganglia (TG) were removed and prepared for SP immunocytochemistry and for preprotachykinin (PPT) autoradiographic in situ hybridization. The SP-like immunofluorescence in TG neurons was subjectively categorized as high, moderate, or low (background) intensity. In situ hybridization autoradiographs were quantified on the basis of grain density using digital imaging analysis. The SP immunoreactivity and PPT mRNA expression in the TG neurons were significantly increased after silica inhalation. The proportion of highly positive SP-immunoreactive neurons shifted from 1.30 +/- 0.58% in controls to 11.30 +/- 1.15% after silica treatment. The neurons exhibiting high grain density for PPT mRNA increased from 1.50 +/- 0.87% in controls to 11.67 +/- 0.58% in the silica group. Thus, inhalation of silica causes upper airway irritation resulting in increased levels of immunoreactive neuronal SP and PPT mRNA. These findings suggest that silica activates sensory pathways that may be involved in nasal inflammation.

Clinical antecedents of neurologic and audiologic abnormalities in survivors of neonatal extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation is an effective rescue treatment for severe cardiorespiratory failure in term or near term neonates, although cerebral palsy, mental retardation, and sensorineural hearing loss are observed in 10 to 20% of survivors. The objective of the present study was to identify potential risk factors that may explain the neurologic and audiologic sequelae noted in 19% of 181 survivors of neonatal extracorporeal membrane oxygenation from our hospital. Our results suggest the following findings in survivors of severe cardiorespiratory failure treated with neonatal extracorporeal membrane oxygenation: (1) hypotension or the need for cardiopulmonary resuscitation before extracorporeal membrane oxygenation significantly increases the risk of spastic cerebral palsy, (2) profound hypocarbia before extracorporeal membrane oxygenation is associated with a significantly increased risk of hearing loss, (3) mental retardation in the absence of spastic cerebral palsy is unexplained except when due to abnormal fetal brain development, and (4) hypoxemia in the absence of hypotension does not increase the risk of neurologic or audiologic sequelae.

Simultaneous 31P MRS of the soleus and gastrocnemius in Sherpas during graded calf muscle exercise

The observation that the amount of lactate formed during hypobaric hypoxia decreases with the severity of hypoxia has become known as the "lactate paradox." We used noninvasive 31P magnetic resonance spectroscopy (MRS) to further probe this problem and explore the nature of muscle metabolism during rest-exercise-recovery transitions in Sherpas indigenous to the high Himalayas of Nepal. MRS data were obtained using a whole body 1-m bore, 1.5-T Phillips Gyroscan spectrometer. Muscle-specific localization of MRS data acquisition was achieved by means of a modified image-selected in vivo spectroscopy sequence (ISIS). The spectra acquired from the medial and lateral gastrocnemius muscle, rich in fast-twitch fibers, were well constrained by selective excitation and by the boundary of the leg. The spectra from a third region contained signals predominantly from the soleus, a muscle formed mainly of slow-twitch fibers. We quantified relative concentration changes in phosphocreatine (PCr), Pi, and ATP during a series of calf muscle work bouts; free ADP concentrations were calculated on the assumption that the creatine phosphokinase reaction was always essentially at equilibrium. Hydrogen ion concentrations were calculated from the chemical shift of Pi, which represents the equilibrium between mono- and diprotonated phosphate. Plantar flexion was quantified using a calf muscle ergometer designed for operation within a 1-m whole body magnet. We found that the concentration of ATP was rigorously regulated and thus did not change despite large changes in ATP turnover rates required through exercise. The relative concentrations of PCr and Pi were linear functions of the percent maximum work rate of the lateral and medial gastrocnemius, but on transition to exercise the fractional concentration changes in these metabolites were much less than the fractional change in muscle ATP turnover rates. The relationship between muscle ATP turnover rate and free ADP concentration was complex; again, a kinetic order of 1 was not observed. In contrast to the gastrocnemius, the soleus muscle sustained much smaller changes in the concentrations of these crucial metabolites during rest-work-recovery transitions. Unlike the situation in most other muscles rich in fast-twitch fibers characterized by lactate-associated acidosis during muscle work, the intracellular pH in gastrocnemius of Sherpas was stable through these protocols, which is consistent with the low lactate production (i.e., with the lactate paradox) observed in indigenous highlanders.

Sensitivity and specificity of the neonatal brain-stem auditory evoked potential for hearing and language deficits in survivors of extracorporeal membrane oxygenation

OBJECTIVE

We determined the sensitivity and specificity of neonatal brain-stem auditory evoked potentials (BAEP) as markers for subsequent hearing impairment and for developmental problems found later in infancy and childhood.

METHODS

BAEP studies were performed before discharge in infants treated with extracorporeal membrane oxygenation (ECMO), and two specific abnormalities were analyzed: elevated threshold and delayed central auditory conduction. Behavioral audiometry was repeated during periodic follow-up until reliable responses were obtained for all frequencies, and standardized developmental testing was also conducted. The sensitivity and specificity of an elevated threshold on the neonatal BAEP for detecting subsequent hearing loss, and the relationship of any neonatal BAEP abnormality to language or developmental disorders in infancy, were calculated.

RESULTS

Test results for 46 ECMO-treated infants (57.5%) were normal, and those for 34 infants (42.5%) were abnormal, with either elevated wave V threshold, prolonged wave I-V interval, or both on neonatal BAEP recordings. Most significantly, 7 (58%) of the 12 children with subsequent sensorineural hearing loss had left the hospital after showing normal results on threshold tests. There was no significant difference in the frequency of hearing loss between subjects with abnormal (5/21, or 24%) and those with normal BAEP thresholds (7/59, or 12%; Fisher Exact Test, p = 0.28). Therefore the sensitivity of neonatal BAEP testing for predicting subsequent hearing loss was only 42%. Neonatal BAEP specificity for excluding subsequent hearing loss was 76%. In contrast, on language development testing, 19 children demonstrated receptive language delay. Of these children, 12 (63%) had abnormal neonatal BAEP recordings and 7 (37%) had a normal BAEP threshold, normal central auditory conduction test results, or both (p = 0.04).

CONCLUSIONS

Neonatal BAEP threshold recordings were of limited value for predicting subsequent hearing loss common in ECMO-treated survivors. However, an abnormal neonatal BAEP significantly increased the probability of finding a receptive language delay during early childhood, even in those with subsequently normal audiometry findings. Because neonatal ECMO is associated with a high risk of hearing and receptive language disorders, parents should be counseled that audiologic and developmental follow-up evaluations in surviving children are essential regardless of the results of neonatal BAEP testing.

A multimodal, second generation, posttraumatic stress disorder rehabilitation program

Second Generation posttraumatic stress disorder (PTSD) treatment programs were recently proposed as one component of a model of treatment of chronic PTSD. While First Generation PTSD programs emphasized trauma work, Second Generation programs emphasize skills for the present/future ability to adapt within society. The present paper describes a functioning Second Generation PTSD treatment program for Vietnam combat veterans. The guiding principles underlying this multimodal and vocational rehabilitation program are outlined.

Effects of hypocarbia on the development of cystic periventricular leukomalacia in premature infants treated with high-frequency jet ventilation

BACKGROUND AND OBJECTIVE

Previous data from our institution indicate that mechanically ventilated premature infants are at increased risk for cystic periventricular leukomalacia (CPVL), particularly if hypocapnia occurs. High-frequency jet ventilation (HFJV) may produce substantial hypocapnia. We sought to investigate whether hypocapnia during HFJV is associated with the development of CPVL.

METHODS

Sixty-seven premature infants (mean gestational age, 27.2 weeks; mean birth weight, 1001 g) underwent HFJV for a mean of 44 (range, 8 to 70) hours during the first 3 days of life. All infants were followed with serial neurosonograms at least weekly until 6 to 8 weeks of age and every 2 to 4 weeks thereafter until discharge. To assess the cumulative effects of hypotension, acidosis, hypoxemia, and hypocarbia during the first 3 days of life on the development of PVL, we developed a quantitative assessment in which we assigned threshold levels at particular critical values of these parameters (such as a mean PaCO2 of 20 mm Hg) and calculated an area above the curve between longitudinally connected values of these parameters and the threshold levels.

RESULTS

Nine of the 67 infants died before 21 days of life. Of the 58 who survived beyond 21 days, large CPVL (> 5 mm in size) developed in 18 infants. Infants with cysts were similar in birth weight, gestational age, and virtually all other antepartum, intrapartum, and postpartum parameters compared with the 40 neonates in whom CPVL did not develop. However, infants with CPVL were significantly more likely to have moderate or severe periventricular echodensities preceding development of CPVL and periventricular echodensities that persisted for a longer period. We did not find an effect of hypotension, acidosis, or hypoxemia on the development of CPVL. There were no differences in the mean PaCO2, the absolute low PaCO2 values, the ranges of low PaCO2 between groups, or area above the curve measurements at threshold levels of 15 and 20 mm Hg, respectively. However, logistic regression analysis revealed that infants with CPVL were independently significantly more likely to have greater cumulative hypocarbia below a threshold level of 25 mm Hg during the first day of life (odds ratio, 5.43; 95% confidence interval, 1.33 to 22.2).

CONCLUSIONS

Hypocarbia produced by treatment with HFJV during the first 3 days of life is associated with the subsequent development of CPVL. The mechanisms for the development of CPVL among premature infants treated with HFJV need to be established.

Sherpa brain glucose metabolism and defense adaptations against chronic hypoxia

The brain of hypoxia-tolerant vertebrates is known to survive extreme oxygen limitation at least in part because of very low rats of ATP utilization and ATP production. To asses whether similar adaptations are involved in healthy humans during hypoxia adaptation over generational time, we initially used positron-emission tomography measurements of glucose metabolic rates in the brain of Quechuas, whose ancestors have been indigenous to the Andes at altitudes between approximately 3,300 and 4,500 m for several hundred years. Workers in this field generally believe that the lineage of Sherpas has been indigenous to the Himalayas for even longer and that Sherpas and other peoples indigenous to the Tibetan plateau are perhaps the most exquisitely hypoxia adapted of all humans. For this reason, in this study we extended our database to include Sherpas. With the use of the same protocol as before, two metabolic states were analyzed: 1) the presumed normal (hypoxia-adapted) state, monitored as soon as possible after subjects left the Himalayas and 2) the deacclimated state, monitored after 3 wk at low altitudes. Positron-emission tomography measurements of 2-[18F]deoxy-2-fluoro-D-glucose metabolic rates, quantified in 26 regions of the brain, indicated that the Sherpas' brain metabolism differed significantly from that of Quechuas but was essentially identical to that of lowlanders. Region-by-region patterns were similar in all three groups, indicating that the regional organization of glucose metabolism in the brain is a conservative, relatively constant characteristic.

31P magnetic resonance spectroscopy of the Sherpa heart: a phosphocreatine/adenosine triphosphate signature of metabolic defense against hypobaric hypoxia

Of all humans thus far studied, Sherpas are considered by many high-altitude biomedical scientists as most exquisitely adapted for life under continuous hypobaric hypoxia. However, little is known about how the heart is protected in hypoxia. Hypoxia defense mechanisms in the Sherpa heart were explored by in vivo, noninvasive 31P magnetic resonance spectroscopy. Six Sherpas were examined under two experimental conditions [normoxic (21% FiO2) and hypoxic (11% FiO2) and in two adaptational states--the acclimated state (on arrival at low-altitude study sites) and the deacclimating state (4 weeks of ongoing exposure to low altitude). Four lowland subjects were used for comparison. We found that the concentration ratios of phosphocreatine (PCr)/adenosine triphosphate (ATP) were maintained at steady-state normoxic values (0.96, SEM = 0.22) that were about half those found in normoxic lowlanders (1.76, SEM = 0.03) monitored the same way at the same time. These differences in heart energetic status between Sherpas and lowlanders compared under normoxic conditions remained highly significant (P < 0.02) even after 4 weeks of deacclimation at low altitudes. In Sherpas under acute hypoxia, the heart rate increased by 20 beats per min from resting values of about 70 beats per min, and the percent saturation of hemoglobin decreased to about 75%. However, these perturbations did not alter the PCr/ATP concentration ratios, which remained at about 50% of the values expected in healthy lowlanders. Because the creatine phosphokinase reaction functions close to equilibrium, these steady-state PCr/ATP ratios presumably coincided with about 3-fold higher free adenosine diphosphate (ADP) concentrations. Higher ADP concentrations (i.e., lower [PCr]/[ATP] ratios) were interpreted to correlate with the Km values for ADP-requiring kinases of glycolysis and to reflect elevated carbohydrate contributions to heart energy needs. This metabolic organization is postulated as advantageous in hypobaria because the ATP yield per O2 molecule is 25-60% higher with glucose than with free fatty acids (the usual fuels utilized in the human heart in postfasting conditions).

The role of infant factors in postnatal depression and mother-infant interactions

A large group of infants of primiparous women who were at high risk fo r postnatal depression (N=188) and a smaller group of those at low risk (N=43) were assessed in the neonatal period using the Neonatal Behavioural Assessment Scale. Poor motor scores and high irritability were strongly predictive of the onset of maternal depression by eight weeks postpartum. These effects obtained after taking account of both maternal mood in the neonatal period and maternal perceptions of infant temperament. Poor motor scores and high levels of infant irritability in the neonatal period also predicted less optimal infant behaviour in face-to-face interactions with the mother at two months postpartum. Neonatal behaviour did not predict the persistence of depression, nor did it predict the quality of maternal behaviour in interaction with the infant.

Sequence-specific purification of nucleic acids by PNA-controlled hybrid selection

Using an oligohistidine peptide nucleic acids (oligohistidine-PNA) chimera, we have developed a rapid hybrid selection method that allows efficient, sequence-specific purification of a target nucleic acid. The method exploits two fundamental features of PNA. First, that PNA binds with high affinity and specificity to its complementary nucleic acid. Second, that amino acids are easily attached to the PNA oligomer during synthesis. We show that a (His)6-PNA chimera exhibits strong binding to chelated Ni2+ ions without compromising its native PNA hybridization properties. We further show that these characteristics allow the (His)6-PNA/DNA complex to be purified by the well-established method of metal ion affinity chromatography using a Ni(2+)-NTA (nitrilotriactic acid) resin. Specificity and efficiency are the touchstones of any nucleic acid purification scheme. We show that the specificity of the (His)6-PNA selection approach is such that oligonucleotides differing by only a single nucleotide can be selectively purified. We also show that large RNAs (2224 nucleotides) can be captured with high efficiency by using multiple (His)6-PNA probes. PNA can hybridize to nucleic acids in low-salt concentrations that destabilize native nucleic acid structures. We demonstrate that this property of PNA can be utilized to purify an oligonucleotide in which the target sequence forms part of an intramolecular stem/loop structure.

Enhanced cardiac metabolism of plasma glucose in high-altitude natives: adaptation against chronic hypoxia

The metabolism of glucose in mammalian heart is 25-50% more O2 efficient than the metabolism of free fatty acids. To assess the role of substrate preference in adaptations to chronic hypoxia, positron emission tomographic measurements of heart regional glucose uptake rates after an overnight fast were made in volunteer Quechua subjects and in Sherpa subjects, both indigenous to altitudes of over 3,000 m, and in a group of lowlander volunteers. Highest uptake rates were found in the Quechuas on arrival and in the Sherpas after a 3-wk period at low altitude, intermediate rates in Quechuas after a 3-wk period at low altitude and in the lowlanders, and lowest rates in Sherpas on arrival. These low values were probably related to the stress of travel to the site of the experiments. Measured plasma catecholamines, hormones, and substrates indicated that glucose concentrations correlated best with observed variations in glucose uptake, with a negative correlation for the control subjects and a positive correlation for the Quechuas and Sherpas. Uptake values in Quechuas declined significantly after a 3-wk period at low altitude, but the positive correlation with glucose levels persisted. We conclude that an elevated glucose preference in heart is a true metabolic adaptation in humans adapted over generations to chronic hypoxia.

The metabolic effects of surface cooling neonates prior to cardiac surgery

Neonates undergoing cardiac surgery at The Children's Hospital of Philadelphia frequently developed metabolic acidemia as they passively cooled prior to the start of cardiopulmonary bypass. This study was performed in an attempt to identify the mechanism for this acidemia. After receiving an initial dose of fentanyl (10 micrograms/kg) and pancuronium, 22 neonates were randomly assigned to maintain normothermia by active warming (Group I), or to permit passive cooling (Group II) before surgery. Arterial blood samples were obtained prior to, and at 10 and 45 min after entering the operating room for the analysis of pH, gas tensions, lactate, pyruvate, plasma free fatty acids, acetoacetate, beta-hydroxybutyrate, total CO2, and glucose concentrations. In the last 11 patients studied, the observation period was extended to 75 min at which time another arterial blood sample was obtained. There was a steady decrease in heart rate as the Group II patients cooled; however, arterial blood pressure did not change in either group. There were no changes in blood values measured in Group I neonates. In the Group II patients, there was a progressive decline in calculated base excess, total CO2, and an increase in serum lactate as the patients cooled. The metabolic acidemia that develops in neonates represents lactate accumulation as a consequence of surface cooling prior to surgery and the institution of cardiopulmonary bypass. Whether lactate accumulates as a result of anaerobic metabolism in underperfused tissue beds or reduced hepatic clearance could not be distinguished in this study. Since neither clinically significant hemodynamic changes nor differences in outcome were found between the two groups, the authors believe this mild lactic acidemia is inconsequential and does not require therapy.

The brain at high altitude: hypometabolism as a defense against chronic hypoxia?

The brain of hypoxia-tolerant vertebrates is known to survive extreme limitations of oxygen in part because of very low rates of energy production and utilization. To assess if similar adaptations may be involved in humans during hypoxia adaptation over generational time, volunteer Quechua natives, indigenous to the high Andes between about 3,700 and 4,900 m altitude, served as subjects in positron emission tomographic measurements of brain regional glucose metabolic rates. Two metabolic states were analyzed: (a) the presumed normal (high altitude-adapted) state monitored as soon as possible after leaving the Andes and (b) the deacclimated state monitored after 3 weeks at low altitudes. Proton nuclear magnetic resonance spectroscopy studies of the Quechua brain found normal spectra, with no indication of any unusual lactate accumulation; in contrast, in hypoxia-tolerant species, a relatively large fraction of the glucose taken up by the brain is released as lactate. Positron emission tomographic measurements of [18F]2-deoxy-2-fluoro-D-glucose (FDG) uptake rates, quantified in 26 regions of the brain, indicated systematically lower region-by-region glucose metabolic rates in Quechuas than in lowlanders. The metabolic reductions were least pronounced in primitive brain structures (e.g., cerebellum) and most pronounced in regions classically associated with higher cortical functions (e.g., frontal cortex). These differences between Quechuas with lifetime exposure to hypobaric hypoxia and lowlanders, which seem to be expressed to some degree in most brain regions examined, may be the result of a defense adaptation against chronic hypoxia.

Single base pair mutation analysis by PNA directed PCR clamping

A novel method that allows direct analysis of single base mutation by the polymerase chain reaction (PCR) is described. The method utilizes the finding that PNAs (peptide nucleic acids) recognize and bind to their complementary nucleic acid sequences with higher thermal stability and specificity than the corresponding deoxyribooligonucleotides and that they cannot function as primers for DNA polymerases. We show that a PNA/DNA complex can effectively block the formation of a PCR product when the PNA is targeted against one of the PCR primer sites. Furthermore, we demonstrate that this blockage allows selective amplification/suppression of target sequences that differ by only one base pair. Finally we show that PNAs can be designed in such a way that blockage can be accomplished when the PNA target sequence is located between the PCR primers.

Developmental data on individuals with the Brachmann-de Lange syndrome

One hundred twenty-two patients with clinically confirmed Brachmann-de Lange syndrome (BDLS) were evaluated developmentally. Recruitment was made from our genetics department and through meetings of the Cornelia de Lange Syndrome Foundation parent support group. Developmental information was obtained from records of physicians, schools and developmental centers, or from parents on each of the 122 individuals, allowing division into four groups for study: group 1 (n = 48) underwent formal developmental assessments, which generated intelligence or developmental quotients, and had a completed parental questionnaire with specific developmental questions regarding ages of skills mastered; group II (n = 23) had additional developmental records available without formal testing, as well as the questionnaire; group III (n = 22) had only a completed questionnaire; and group IV (n = 29) had formal developmental testing or other developmental records but no available questionnaire. These data were analyzed in order to be able to predict attainable psychomotor development. Average scores on formal testing were found to be in the mild to moderate level of mental retardation, ranging from below 30 to 85, with an average intelligence quotient of 53, higher than previously reported. Visual-spatial memory and perceptual organization skills were found to be strengths. Younger individuals born before 1980 demonstrated higher scores on testing. Early intervention appears to play a major role in the level of developmental achievement.

UV-A-mediated activity of p-methoxymethylcinnamate

Methyl esters of hydroxycinnamic acids are photobiologically active. Cis(Z) and trans(E) p-methoxymethyl-cinnamate photosensitize Escherichia coli and Chinese hamster ovary cells. They also produce sister chromatid exchanges. Photosensitization is oxygen independent, and the cinnamates are not genetically active in the absence of light in the Ames Salmonella typhimurium test.

Nephrolithiasis, hypocitraturia, and a distal renal tubular acidification defect in type 1 glycogen storage disease

Renal stones containing calcium can occur in patients with type 1 glycogen storage disease. We studied 11 patients with glycogen storage disease. Five patients had renal calculi, nephrocalcinosis, or both, and five had hypercalciuria. Serum levels of calcium, phosphorus, parathyroid hormone, and urate were normal. Serum levels of 1,25-dihydroxyvitamin D were elevated in each patient. None of the patients had a metabolic acidosis, but all nine who were tested had evidence of impaired acid excretion. In response to an acid load, eight of the nine patients had subnormal titratable acid excretion, and nine had subnormal ammonia excretion; six of nine patients were unable to secrete hydrogen ions in response to bicarbonate administration. These data indicate that patients with type 1 glycogen storage disease have an incomplete form of distal renal tubular acidosis. This may be the cause of hypercalciuria and nephrocalcinosis in these patients.

Reed-Sternberg cells in sputum from a patient with Hodgkin's disease. A case report

A patient with stage IV Hodgkin's disease developed severe dyspnea and was found to have pulmonary infiltrates one year following his initial diagnosis of nodular sclerosing Hodgkin's disease, stage IIB. Two separate cell block sputum cytology samples demonstrated Reed-Sternberg cells. The patient died of respiratory failure. At autopsy the main findings were extensive confluent nodules of Hodgkin's disease nearly replacing the pulmonary parenchyma of both lungs. Cytology of sputum or bronchial washings may reveal diagnostic Reed-Sternberg cells and establish the diagnosis of pulmonary Hodgkin's disease without a lung biopsy.

Mechanical ventilation in preterm infants: neurosonographic and developmental studies

Surviving preterm infants of less than 34 weeks' gestation who were selected on the basis of serial cranial ultrasonographic findings during their nursery course had repeated neurologic and developmental examinations during late infancy and early childhood that established the presence (n = 46) or absence (n = 205) of spastic forms of cerebral palsy. Of the 205 infants without cerebral palsy, 22 scored abnormally low on standardized developmental testing during early childhood. The need for mechanical ventilation beginning on the first day of life (n = 92) was significantly related to gestational age, birth weight, Apgar scores, patent ductus arteriosus, grade III/IV intracranial hemorrhage, large periventricular cysts, and the development of cerebral palsy. In the 192 mechanically ventilated infants, vaginal bleeding during the third trimester, low Apgar scores, and maximally low PCO2 values during the first 3 days of life were significantly related to large periventricular cysts (n = 41) and cerebral palsy (n = 43), but not to developmental delay in the absence of cerebral palsy (n = 18). The severity of intracranial hemorrhage in mechanically ventilated infants was significantly associated with gestational age and maximally low measurements of PCO2 and pH, but not with Apgar scores or maximally low measurements of PO2. Logistic regression analyses controlling for possible confounding variables disclosed that PCO2 values of less than 17 mm Hg during the first 3 days of life in mechanically ventilated infants were associated with a significantly increased risk of moderate to severe periventricular echodensity, large periventricular cysts, grade III/IV intracranial hemorrhage, and cerebral palsy. Neurosonographic abnormalities were highly predictive of cerebral palsy independent of PCO2 measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Enzyme mechanisms for pyruvate-to-lactate flux attenuation: a study of Sherpas, Quechuas, and hummingbirds

During incremental exercise to fatigue under hypobaric hypoxia, Andean Quechua natives form and accumulate less plasma lactate than do lowlanders under similar conditions. This phenomenon of low lactate accumulation despite hypobaric hypoxia, first discovered some half century ago, is known in Quechuas to be largely unaffected by acute exposure to hypoxia or by acclimatization to sea level conditions. Earlier Nuclear Magnetic Resonance (NMR) spectroscopy and metabolic biochemistry studies suggest that closer coupling of energy demand and energy supply in Quechuas allows given changes in work rate with relatively modest changes in muscle adenylate and phosphagen concentrations, thus tempering the activation of glycolytic flux to pyruvate--a coarse control mechanism operating at the level of overall pathway flux. Later studies of enzyme activities in skeletal muscles of Quechuas and of Sherpas have identified a finely-tuned control mechanism which by adaptive modifications of a few key enzymes apparently serves to specifically attenuate pyruvate flux to lactate.