Geomorphic and geologic controls of geohazards induced by Nepal's 2015 Gorkha earthquake

The Gorkha earthquake (magnitude 7.8) on 25 April 2015 and later aftershocks struck South Asia, killing ~9000 people and damaging a large region. Supported by a large campaign of responsive satellite data acquisitions over the earthquake disaster zone, our team undertook a satellite image survey of the earthquakes' induced geohazards in Nepal and China and an assessment of the geomorphic, tectonic, and lithologic controls on quake-induced landslides. Timely analysis and communication aided response and recovery and informed decision-makers. We mapped 4312 coseismic and postseismic landslides. We also surveyed 491 glacier lakes for earthquake damage but found only nine landslide-impacted lakes and no visible satellite evidence of outbursts. Landslide densities correlate with slope, peak ground acceleration, surface downdrop, and specific metamorphic lithologies and large plutonic intrusions.

Clinical phenotype of X-linked myotubular myopathy in Labrador Retriever puppies

Background

Seven male Labrador Retriever puppies from 3 different litters, born to clinically normal dams and sires, were evaluated for progressive weakness and muscle atrophy. Muscle biopsies identified a congenital myopathy with pathologic features consistent with myotubular myopathy. Further investigations identified a pathogenic mutation in the myotubularin gene, confirming that these puppies had X‐linked myotubular myopathy (XLMTM).

Objective

To review the clinical phenotype, electrodiagnostic and laboratory features of XLMTM in this cohort of Labrador Retrievers.

Results

Male puppies with XLMTM were small and thin compared with their normal littermates. Generalized weakness and muscle atrophy were present by 7 weeks of age in some puppies and evident to most owners by 14 weeks of age. Affected puppies stood with an arched spine and low head carriage, and walked with a short, choppy stride. Muscle atrophy was severe and progressive. Patellar reflexes were absent. Laryngeal and esophageal dysfunction, and weakness of the masticatory muscles occurred in puppies surviving beyond 4 months of age. Serum creatine kinase activity was normal or only mildly increased. EMG findings were nonspecific and included positive sharp waves and fibrillation potentials. Clinical signs progressed rapidly, with most affected puppies unable to walk within 3–4 weeks after clinical signs were first noticed.

Conclusions and Clinical Importance

Although initial clinical signs of XLMTM are similar to the phenotypically milder centronuclear myopathy in Labrador Retrievers, XLMTM is a rapidly progressive and fatal myopathy. Clinicians should be aware of these 2 distinct myopathies with similar clinical presentations in the Labrador retriever breed.

In vivo angiogenesis in normal and portal hypertensive rats: role of basic fibroblast growth factor and nitric oxide

BACKGROUND

Angiogenesis plays a pivotal role in many processes. Here, we studied whether angiogenesis to basic fibroblast growth factor (bFGF) in normal and portal hypertensive rats requires nitric oxide (NO).

METHODS

To measure angiogenesis in vivo, two Teflon rings filled with collagen I (Vitrogen 100) were fixed in the mesenteric cavity at day 0, with one supplemented with bFGF (100 ng). Portal hypertension was induced by partial portal vein ligation (PVL). Sham-operated rats served as controls (CON). The role of NO was tested by adding the NO formation antagonist N(omega)-nitro-L-arginine (NNA; 3.3 mg/kg per day) to the drinking water. After 16 days, rings were explanted and embedded, and vessels were morphometrically counted.

RESULTS

bFGF significantly stimulated vessel formation per implant in CON rats (from 624 +/- 97 without stimulation to 1123 +/- 171, n = 11, P < 0.01), but not in PVL rats (from 1106 +/- 174 without stimulation to 1046 +/- 202, n = 9). Without stimulation, numbers of ingrown vessels were significantly (P < 0.05) higher in PVL compared to CON rats. NNA substantially inhibited angiogenesis in both groups (P < 0.01). Vessel numbers were 202 +/- 124 for PVL (n = 5) and 197 +/- 14 for CON (n = 5) animals. bFGF did not reverse angiogenesis prevented by NNA (373 +/- 98 for PVL, 265 +/- 26 for CON, n = 5 per group, NS).

CONCLUSIONS

NO formation inhibition diminishes both unstimulated and bFGF-stimulated angiogenesis in CON rats. Moreover, bFGF cannot rescue NNA-inhibited angiogenesis in PVL rats.

Increased angiogenesis in portal hypertensive rats: role of nitric oxide

Systemic and especially splanchnic arterial vasodilation accompany chronic portal hypertension. Different soluble mediators causing this vasodilation have been proposed, the strongest evidence being for nitric oxide (NO). No data exist if structural vascular changes may partly account for this vasodilatory state. Here, we developed a new in vivo quantitative angiogenesis assay in the abdominal cavity and determined if: 1) portal hypertensive rats show increased angiogenesis; and 2) angiogenesis is altered by inhibiting NO formation. Portal hypertension was induced by partial portal vein ligation (PVL). Sham-operated rats served as controls (CON). During the index operation (day 0), a teflon ring filled with collagen I (Vitrogen 100) was sutured in the mesenteric cavity. After 16 days, rings were explanted, embedded in paraffin, and ingrown vessels counted using a morphometry system. The role of NO was tested by adding an antagonist of NO formation (Nomega-nitro-L-arginine [NNA], 3.3 mg/kg/d) into the drinking water. The mean number of ingrown vessels per implant was significantly higher in PVL rats compared with CON rats, i.e., 1,453 +/- 187 versus 888 +/- 116, respectively (P <.05; N = 5 per group). NNA significantly (P <.01) inhibited angiogenesis in PVL (202 +/- 124; N = 5) and in CON (174 +/- 25; N = 6) rats, respectively. In contrast, the beta-adrenergic blocker, propranolol, did not prevent angiogenesis either in PVL or CON rats in a separate set of experiments (data not shown). The conclusions drawn from this study are that: 1) rats with portal hypertension show increased angiogenesis; and 2) inhibition of NO formation significantly prevents angiogenesis in both PVL and CON rats. Therefore, splanchnic vasodilation in chronic portal hypertension may also be a result of structural changes.

Development of lipoprotein-like lipid particles for drug targeting: neo-high density lipoproteins

The possibility was explored of synthesizing, from commercially available lipids, high density lipoprotein (HDL)-like particles (neo-HDL) with the same physico-chemical and biological properties as native HDL. A preparation method involving egg yolk phosphatidylcholine, cholesterol, and apoproteins from HDL led to the formation of particles with a composition, size, electrophoretic mobility, and density similar to those of discoidal HDL. In vitro experiments with isolated parenchymal liver cells showed that unlabeled HDL and neo-HDL competed for the same high affinity binding sites as did radiolabeled neo-HDL, whereas an excess of unlabeled low density lipoprotein was ineffective. In vivo experiments with radio-labeled neo-HDL indicated that neo-HDL showed a slow decay upon injection into rats, whereas the liver uptake did not exceed > 10% of the injected dose. The small additional liver uptake of radioactivity from neo-HDL, compared with HDL, was due to enhanced uptake by endothelial and Kupffer cells. Lactosylation of neo-HDL led to a markedly increased decay rate and a rapid uptake by rat liver (80% in 10 min). Parenchymal cells accounted for > 90% of the total liver uptake of radiolabeled lactosylated neo-HDL. Because the liver uptake of lactosylated 125I-neo-HDL could be blocked by preinjection of N-acetylgalactosamine, we conclude that the asialoglycoprotein receptor, which is specifically localized on parenchymal liver cells, is responsible for the avid liver uptake. With a fibroblast cell line transfected with the human asialoglycoprotein receptor, it was found that lactosylated neo-HDL binds with high affinity (Kd, 40 nM), in a galactose-specific way. It can be concluded that, with commercially available lipid components, HDL-like particles (neo-HDL) with virtually the same characteristics as found for native apolipoprotein E-free HDL can be reconstituted. Lactosylated neo-HDL, which is rapidly taken up by galactose-specific receptors on parenchymal liver cells, might be used to transport antiviral drugs specifically to parenchymal liver cells.