Bird lung models show that convective inertia effects inspiratory aerodynamic valving

We assessed various aerodynamic factors which might influence inspiratory valve function in the avian lung. During inspiration, no flow enters the proximal segments of the ventrobronchi connecting the primary bronchus to cranial sacs. Instead, all flow in the primary bronchus continues through the mesobronchus. This pattern of flow past the ventrobronchi into the mesobronchus is called inspiratory aerodynamic valving. Introducing steady inspiratory flows into simplified plastic models of a bifurcation, we altered geometry, downstream resistance, flow rate and gas density while we measured the resulting flow partitioning between downstream branches. We found that these models did reproduce the inspiratory valving phenomenon. Gas flow rate, gas density and geometry upstream of the bifurcation played important roles in flow partitioning, but the geometry and branching angles of the ventrobronchi did not. These findings are consistent with the idea that convective inertia of the inspiratory gas stream promotes preferential axial flow (Butler et al., 1988) and may be the principal mechanism accounting for inspiratory aerodynamic valving in the avian lung.     

Infants thinner at birth exhibit smaller kidneys for their size in late gestation in a sample of fetuses with appropriate growth

Fetal ultrasound measurements were employed to investigate the relationship between weight and ponderal index at birth and kidney size during the second (23 weeks) and third (32 weeks) trimesters of pregnancy in a sample of 25 normally growing fetuses. Kidney volume and kidney volume / fetal weight ratio at 32 weeks are significantly and positively related to both weight and ponderal index at birth, controlling for sex, gestational age at birth, and day of ultrasound measurement. A second‐degree polynomial relationship approximates the predictability of kidney volume fetal weight ratio at 23 weeks to that at 32 weeks, demonstrating shifting growth rates in fetal organ and body growth relationships during midgestation. Sex and parental size are suggested as contributing to these patterns. Females have a surge in renal growth between 23 and 32 weeks to catch up to earlier growing males, and maternal weight significantly predicts incremental growth in kidney volume and the kidney volume / fetal weight ratio at 32 weeks of gestation. The observation that fetuses relatively thin at birth have relatively smaller kidneys for their size in late gestation suggests that the influence of maternal weight on birth outcome may act through organ growth. Am. J. Hum. Biol. 14:398–406, 2002. © 2002 Wiley‐Liss, Inc.     

Best evidence in critical care medicine Selective digestive decontamination decreases mortality and morbidity in the intensive care

SDD reduces ICU and in-hospital mortality, the length-of-stay in the ICU, the frequency of colonization with resistant GNB, and the total costs of antibiotic treatment. This supports the use of SDD in all patients expected to be on mechanical ventilation for at least two days in ICUs that have low prevalence of VRE and MRSA.     

Pituitary volume in pediatric obsessive-compulsive disorder.

BACKGROUND: Abnormalities in the limbic-hypothalamic-pituitary-adrenal (LHPA) axis have been implicated in the pathogenesis of obsessive-compulsive disorder (OCD). To our knowledge, however, no prior study has measured pituitary gland volume in OCD. METHODS: Volumetric magnetic resonance imaging studies were conducted in 31 psychotropic drug-na?ve children (10 boys, 21 girls) aged 8-17 years and 31 case-matched healthy comparison subjects. RESULTS: Pituitary volume was significantly smaller in patients with OCD as compared with healthy control subjects (11% smaller). Smaller pituitary volume in patients with OCD was associated with increased compulsive but not obsessive symptom severity. Boys with OCD had smaller pituitary gland volumes compared with control boys (20% smaller). No significant differences in pituitary volume were observed between girls with OCD and control girls. Boys with OCD had significantly smaller pituitary volumes than girls with OCD (31% smaller), whereas control boys also had smaller pituitary gland volumes compared with control girls (21% smaller). CONCLUSIONS: These findings provide new evidence of reduced pituitary volume in pediatric OCD that seems to be more prominent in male patients. The observed alterations in pituitary volume are consistent with neuroendocrine studies that have reported abnormalities in the LHPA axis in OCD.     

Tongue oximetry in children with extensive thermal injury: comparison with peripheral oximetry

We undertook a prospective study of standard peripheral pulse oximetry versus a modified pulse oximeter probe applied to the tongue in order to determine the efficacy of this alternative monitoring site in children with thermal injuries. Ten patients with a mean age (± SD) of 7.5 ± 4.5 yr were studied on 15 occasions. The mean weight +- SD) was 31.4+- 13.7 kg and percent surface area burn (± SD) was 56+- 21%. A total of 1,992 min of anaesthesia time was monitored. Both sites functioned simultaneously 47% of the time; the lingual but not the peripheral site functioned 28% of the time and only the peripheral site and not the lingual functioned 22% of the time. Neither site functioned 3% of the time. The tongue oximeter provided 563 min more monitoring time than the peripheral sites. The tongue oximeter also functioned in children with peripheral vasoconstriction when the peripheral sensor failed and was less susceptible to electrocautery interference. The tongue oximeter is a reasonable adjunct but not a substitute for peripheral oximetry since its application is limited to paralyzed, intubated patients.     

Monocular contribution to the peak time of the binocular pattern visual evoked potential

The contribution of each monocular pathway to the timing of the binocular pattern visual evoked potential was assessed in situations where a significant interocular timing discrepancy was observed. Monocular and binocular pattern visual evoked potentials to 0.5° checks were recorded from normal subjects, normal subjects in whom one eye was blurred, patients with monocular amblyopia, and patients with resolved unilateral optic neuritis. Normal subjects showed facilitation, while suppression was evidenced in subjects with monocular blurring. In patients with amblyopia, the affected pathway had no effect on binocular pattern visual evoked potential latency, suggesting that the amblyopic eye was suppressed. In contrast, all patients with optic neuritis showed binocular averaging. Our results show that different forms of binocular interaction are evidenced in normal subjects, in amblyopia and in optic neuritis, and suggest that a comparative analysis of monocular and binocular pattern visual evoked potential peak times brings valuable information to the clinical evaluation that could be used to distinguish disease processes further.Abbreviation BPVEP binocular pattern visual evoked potential     

Paraimmunoblastic variant of small lymphocytic lymphoma/leukemia

We report 16 cases of a distinctive, biologically aggressive variant of small lymphocytic lymphoma/leukemia (SLL/L) that is characterized by the diffuse proliferation of cells normally comprising the pseudoproliferation centers (so-called paraimmunoblasts). Demographically, the patients differed in no significant regard from patients with SLL/L of usual type. Rapidly progressive, generalized lymphadenopathy was the dominant clinical finding in 15 of the 16 patients; one patient presented with symptoms related to lymphomatous involvement of the stomach and regional lymph nodes. Splenomegaly was observed in five patients. Seven patients, two of whom had a history of indolent-phase chronic lymphocytic leukemia, had an absolute lymphocytosis at diagnosis. In most patients, bone marrow involvement was noted at diagnosis. It consisted predominantly of small lymphocytic infiltrates indistinguishable from those observed in SLL/L of usual type; significant paraimmunoblastic infiltration was infrequent and generally occurred late in the disease course. Immunohistochemical and cytogenetic study further substantiated the hypothesized relationship of these cases to SLL/L. Findings included (a) coexpression of sIg and Leu-1 antigen in the majority of cases and (b) the presence of a t(11;14) (q13;q32) chromosome translocation in two of three cases with analyzable metaphases. Although treatment protocols were not uniform, follow-up data indicated an accelerated clinical course. Eleven patients have died of their disease between 3 and 39 months after diagnosis; the median survival was 28 months.     

Studies on the molecular pharmacology of GR63178A. A novel pentacyclic pyrolloquinone anticancer drug.

GR63178A (NSC D611615) is the second pentacyclic pyrolloquinone to be evaluated clinically as an anticancer drug. Its mechanism of action is unknown but may be related either to its quinone group or planar ring system. In this report we have investigated the ability of GR63178A to bind non-covalently to DNA, inhibit topoisomerase II and undergo reduction to reactive free radical species. Using two DNA duplexes, a 12-mer oligonucleotide which is a preferred sequence for minor groove binders and a hexamer which is a preferred sequence for intercalators, no evidence of significant binding with GR63178A was found. Neither GR63178A nor GR54374X (its 9-hydroxy metabolite) inhibited purified human topoisomerase II in a decatenation assay. Free radical chemistry was studied by both pulse radiolysis and ESR spectroscopy as well as by in vitro drug incubations with NADPH-fortified rat liver microsomes and purified cytochrome P450 reductase. The one-electron reduction potential of GR63178A was -207 mV +/- 10 which is much more positive than other quinone-containing anticancer drugs such as doxorubicin, mitomycin C and mitozantrone. GR63178A underwent enzyme-catalysed quinone reduction more readily than doxorubicin but produced significantly fewer reactive oxygen species. No evidence was detected of drug-induced, radical-mediated DNA damage in vitro using pBR322 plasmid DNA. Disproportionation of the GR63178A semi-quinone free radical proceeded with a rate constant of 1 x 10(9) M-1 sec-1 under anaerobic conditions, one order of magnitude faster than doxorubicin. The preferential disproportionation of the semi-quinone may explain our inability to detect a free radical signal by ESR. The hydroquinone of GR63178A was stable and exhibited strong visible absorption with a bathochromic shift of 120 nm over the parent drug. These unusual properties may be due to the hydroquinone undergoing a form of keto-enol tautomerization. Thus, GR63178A free radical formation does not appear to result in significant drug activation. In conclusion, GR63178A is unlikely to mediate its antitumour activity by DNA binding, topoisomerase II inhibition or free radical formation in direct contrast to similar anthracycline- and anthraquinone-based anticancer drugs.