Hypoglycemia and glycogen deficits in fetuses of hypothyroid pregnant rats.

Maternal hypothyroidism, when induced by surgical thyroidectomy with parathyroid hormone replacement, results in fewer live fetuses and smaller fetuses at the 22nd day of gestation. The hypothyroid mother shows the ability to mobilize adequate amounts of glucose even at the expense of her own reserves but the supply of glucose to the fetus appears to be impaired. These fetuses have subnormal skeletal muscle and liver glycogen and are severely hypoglycemic. The impaired development of these fetuses may result from alterations of either transplacental carbohydrate transport or placentofetal carbohydrate metabolism.     

Profile of gastrointestinal damage induced by platelet-activating factor

The ulcerogenic actions of an intravenous infusion of platelet-activating factor (100 ng/kg/min) was studied in the rat. Damage to the stomach, duodenum, jejunum, ileum and colon were assessed histologically and using intraluminal acid phosphatase release as a marker of cellular damage. A 10-min infusion of platelet-activating factor caused extensive haemorrhagic damage to each of the regions examined, with the exception of the colon. Acid phosphatase release was significantly elevated in the stomach, jejunum, ileum (p less than 0.001) and duodenum (p less than 0.01), but not in the colon. These studies demonstrate that platelet-activating factor is a potent ulcerogen in the stomach and small intestine, and support a role for this endogenous phospholipid as a mediator of the ulceration associated with endotoxin-induced shock.     

Differential distribution of nitric oxide synthase between cell fractions isolated from the rat gastric mucosa.

Cells isolated from the rat gastric mucosa were resolved into two fractions on a percoll density gradient, and into five fractions using counterflow centrifugation (elutriation). Ca(2+)-dependent nitric oxide synthase (NOS) activity was found in the high density percoll fraction but not in the parietal cell enriched low density fraction. This activity was inhibited by NG-monomethyl-L-arginine with an IC50 of 3.7 microM. Cells in the elutriator fraction rich in mucous-epithelial cells exhibited the highest NOS activity, while the smaller cell fractions had no detectable NOS yet had the highest basal release of prostaglandin E2. The parietal cell enriched elutriator fraction again had low NOS activity. The activity of a constitutive NOS in the mucous-cell fraction may indicate a role of NO in the regulation of epithelial cell integrity or secretion.     

The utility of the morphological variation of pollen for resolving the evolutionary history of Billia (subfam. Hippocastanoideae,Sapindaceae)

In this study, we examined the utility of pollen morphology for resolving questions about the evolutionary history of Billia, which is a poorly known genus of Neotropical trees. Billia has been traditionally circumscribed with two species and treated as sister to Aesculus L. However, the number of species in Billia is uncertain, because the genus exhibits abundant morphological diversity but little discontinuous variation. Therefore, Billia may be monotypic and highly polymorphic, or it may have two species with blurred boundaries due to incipient speciation and/or hybridization. Moreover, one recent molecular phylogenetic study shows Billia nested withinAesculus. Our work sought to address the following questions: (i) Are there discontinuities in the pollen of Billia that may suggest species boundaries? (ii) Does the pollen of Billia show evidence for inter-specific hybridization? (iii) Do the exine morphology and size of pollen in Billia differ from those in Aesculus? Our results from scanning electron microscopy showed that pollen exine morphology is not taxonomically informative in Billia but that there are significant differences in pollen size between red- and white-flowered individuals. Thus, our pollen data support the utility of flower color in Billia for species delimitation. Our assessments of pollen viability do not support hybridization in the genus, but cannot be used to rule it out. Finally, pollen exine morphology may lend some support to an evolutionary origin ofBillia within eastern North American Aesculus. In contrast, data on pollen size suggest that Billia may belong in a topological position outside of Aesculus.     

PA,a stress-induced short cut to switch-on ethylene signalling by switching-off CTR1?

Constitutive triple response 1 (CTR1) is a protein kinase that represses plant responses to ethylene. Recently, we have shown that CTR1 function is negatively regulated by the lipid second messenger phosphatidic acid (PA) in vitro.¹ PA was shown to inhibit (1) CTR1''s protein kinase activity, (2) the intramolecular interaction between N-terminus and kinase domain, and (3) the interaction of CTR1 with the ethylene receptor ETR1. PA typically accumulates within minutes in response to biotic or abiotic stresses, which are known to induce ethylene formation. Although long-term treatment with ethephon does stimulate PA accumulation, our results show no fast increase in PA in response to ethylene. A speculative model is presented which explains how stress-induced PA formation could switch on downstream ethylene responses via interaction of the lipid with CTR1.Key words: lipid signaling, phosphatidic acid, ethylene, constitutive triple response 1, plant stress signaling, protein kinase, phospholipase D     

Time Space Translation: A Hox Mechanism for Vertebrate A-P Patterning

The vertebrate A-P axis is a time axis. The head is made first and more and more posterior levels are made at later and later stages. This is different to the situation in most other animals, for example, in Drosophila. Central to this timing is Hox temporal collinearity (see below). This occurs rarely in the animal kingdom but is characteristic of vertebrates and is used to generate the primary axial Hox pattern using time space translation and to integrate successive derived patterns (see below). This is thus a different situation than in Drosophila, where the primary pattern guiding Hox spatial collinearity is generated externally, by the gap and segmentation genes.     

The high-resolution NMR structure of the R21A Spc-SH3:P41 complex: Understanding the determinants of binding affinity by comparison with Abl-SH3

Background  

SH3 domains are small protein modules of 60–85 amino acids that bind to short proline-rich sequences with moderate-to-low affinity and specificity. Interactions with SH3 domains play a crucial role in regulation of many cellular processes (some are related to cancer and AIDS) and have thus been interesting targets in drug design. The decapeptide APSYSPPPPP (p41) binds with relatively high affinity to the SH3 domain of the Abl tyrosine kinase (Abl-SH3), while it has a 100 times lower affinity for the α-spectrin SH3 domain (Spc-SH3).     

HTLV-1 and HIV-2 infection are associated with increased mortality in a rural West African community

Background

Survival of people with HIV-2 and HTLV-1 infection is better than that of HIV-1 infected people, but long-term follow-up data are rare. We compared mortality rates of HIV-1, HIV-2, and HTLV-1 infected subjects with those of retrovirus-uninfected people in a rural community in Guinea-Bissau.

Methods

In 1990, 1997 and 2007, adult residents (aged ≥15 years) were interviewed, a blood sample was drawn and retroviral status was determined. An annual census was used to ascertain the vital status of all subjects. Cox regression analysis was used to estimate mortality hazard ratios (HR), comparing retrovirus-infected versus uninfected people.

Results

A total of 5376 subjects were included; 197 with HIV-1, 424 with HIV-2 and 325 with HTLV-1 infection. The median follow-up time was 10.9 years (range 0.0–20.3). The crude mortality rates were 9.6 per 100 person-years of observation (95% confidence interval 7.1-12.9) for HIV-1, 4.1 (3.4–5.0) for HIV-2, 3.6 (2.9–4.6) for HTLV-1, and 1.6 (1.5–1.8) for retrovirus-negative subjects. The HR comparing the mortality rate of infected to that of uninfected subjects varied significantly with age. The adjusted HR for HIV-1 infection varied from 4.0 in the oldest age group (≥60 years) to 12.7 in the youngest (15–29 years). The HR for HIV-2 infection varied from 1.2 (oldest) to 9.1 (youngest), and for HTLV-1 infection from 1.2 (oldest) to 3.8 (youngest).

Conclusions

HTLV-1 infection is associated with significantly increased mortality. The mortality rate of HIV-2 infection, although lower than that of HIV-1 infection, is also increased, especially among young people.