Indian hedgehog supports definitive erythropoiesis

Indian hedgehog (Ihh) has been reported to stimulate haematopoiesis ex vivo. In this study we studied the consequences of loss of function of Ihh for murine haematopoietic development. Ihh has no essential role in primitive erythropoiesis, but it is required in a non cell autonomous fashion for definitive erythropoieisis. Many components of the hedgehog signaling pathway are present in the fetal liver, with Ihh and Gli1 being most highly expressed in the stroma and Ptc1 being most highly expressed in haematopoietic stem and progenitor cells. Ihh knockout HSC and progenitor cell populations are produced in normal numbers in vivo and respond normally to haematopoietic cytokines in vitro, but terminal erythroid differentiation is defective leading to fatal anemia in mid gestation in many Ihh knockout embryos. These loss-of-function studies are consistent with previous gain-of-function studies which show Ihh can induce blood from ectoderm or expand HSCs in stroma-dependent culture.     

OBSTETRIC OUTCOMES IN AN ABORIGINAL COMMUNITY: A COMPARISON WITH THE SURROUNDING RURAL AREA

Antenatal, intranatal and postnatal features of all Aboriginal women who lived at Cherbourg Aboriginal Community and delivered during 1990, 1991 and 1992 were compared with all non-Aboriginal women in the same rural area who delivered at Kingaroy Base Hospital during 1991. Almost all the Aboriginal women also delivered at Kingaroy. The data for 146 Aboriginal and 139 non-Aboriginal women were taken from the hospital records. The Aboriginal women were generally younger at delivery (Aboriginal 35% younger than 20 years vs non-Aboriginal 12%), made their first antenatal visit later (Aboriginal 49% after 20 weeks vs non-Aboriginal 10%) and made fewer antenatal visits (Aboriginal 43% < 4 visits vs non-Aboriginal 2% < 4 visits). They were more likely to be anaemic (Aboriginal 65% < 110 g/L vs non-Aboriginal 13% < 110 g/L), have a sexually transmitted disease (STD; Aboriginal 13% vs non-Aboriginal 2%) and drink alcohol (Aboriginal 54% vs non-Aboriginal 32%). After making an allowance for repeat Caesarean sections, there was no significant difference in the proportion of abnormal deliveries, but birthweights of Aboriginal infants were lower. Postnatally, the only significant difference between the two groups was a lower incidence of jaundice in Aboriginal infants. Multifactorial analysis showed that birthweights were significantly decreased by primagravidy, alcohol intake and STD. It is likely that the effects of STD and alcohol on birthweight were due to associated lifestyle factors. When these factors were allowed for, ethnic background had no significant effect on birthweight.     

Wallerian degeneration after cerebral infarction: evaluation with sequential MR imaging

The dynamic signal intensity changes at magnetic resonance (MR) imaging in active and chronic wallerian degeneration in the corticospinal tract were evaluated. Forty-three patients with wallerian degeneration seen on MR images after cerebral infarction were studied. When possible, patients with acute stroke were examined with MR imaging prospectively at the onset of symptoms and then at weekly intervals for several months. Focal infarction without distal axonal degeneration is demonstrated for the 1st month following onset of clinical symptoms. At 4 weeks, a well-defined band of hypointense signal appears on T2-weighted images in the topographic distribution of the corticospinal tract. After 10-14 weeks, the signal becomes permanently hyperintense. Over several years, accompanying ipsilateral brain stem shrinkage occurs. The dark signal intensity observed on T2-weighted images between 4 and 14 weeks is believed to result primarily from transitory increased lipid-protein ratio.     

Nighttime Hypoxemia Is Increased in Abstaining Chronic Alcoholic Men

Previously we reported that abstaining chronic alcoholic men demonstrated significantly more nighttime hypoxemia than a control group. Here, we report a replication employing a larger sample of abstaining chronic alcoholics and a more appropriate control group than that used in the previous study. Forty-seven males, 48.4 +/- 1.7 years of age (mean +/- SEM), reporting 24.8 +/- 1.5 years of heavy alcohol use, comprised the abstaining alcohol group. Thirty-five age- and weight-matched males, 50.3 +/- 1.7 years were the control group. The alcohol group had significantly more nighttime oxygen desaturations below 90% than did the control group (16.9 +/- 3.3 vs. 6.2 +/- 1.4, F = 7.8, p less than 0.01), with significantly higher percentages of individuals in the alcohol group manifesting more than 10 or 20 oxygen desaturations below 90%. Regression analyses within the alcohol group revealed that severity of alcohol abuse, but not age, body mass index, days abstinent, or smoking significantly predicted levels of nighttime hypoxemia. These results confirm our original observation of increased nighttime hypoxemia in abstaining chronic alcoholic men and suggest that long-term alcohol abuse may be a risk factor for development of sleep apnea.     

Phenylephrine infusion impact on surgical site infections after lower extremity bypass surgery

Objective

Lower extremity bypass (LEB) operations have high rates of surgical site infections (SSI). Phenylephrine is a commonly used vasoconstrictor which may reduce skin blood flow and increase the likelihood of SSI in these patients. We studied the potential effect of phenylephrine infusion during LEB surgery on SSI.

Hemispheric asymmetry in global/local processing: effects of stimulus position and spatial frequency

We examined the neural mechanisms of functional asymmetry between hemispheres in the processing of global and local information of hierarchical stimuli by measuring hemodynamic responses with functional magnetic resonance imaging (fMRI). In a selective attention task, subjects responded to targets at the global or local level of compound letters that were (1) broadband in spatial-frequency spectrum and presented at fixation; (2) broadband and presented randomly to the left or the right of fixation; or (3) contrast balanced (CB) to remove low spatial frequencies (SFs) and presented at fixation. Central broadband stimuli induced stronger activation in the right middle occipital cortex under global relative to local attention conditions but in the left inferior occipital cortex, stronger activation was induced under local relative to global attention conditions. The asymmetry over the occipital cortex was weakened by unilateral presentation and by contrast balancing. The results indicate that the lateralization of global and local processing is modulated by the position and SF spectrum of the compound stimuli. The global attention also produced stronger activation over the medial occipital cortex relative to the local attention under all the stimulus conditions. The nature of these effects is discussed.