Failure of Ixodes ticks to inherit Borrelia afzelii infection

To define conditions promoting inherited infection by Lyme disease spirochetes in Ixodes ticks, we variously infected ticks with Borrelia afzelii and examined their progenies by dark-field microscopy, immunofluorescence, PCR, and serial passage. No episode of inherited infection was evident, regardless of instar or gender infected or frequency of exposure. We suggest that these spirochetes rarely, if ever, are inherited by vector ticks.     

Measurements of exit rates to distinguish between facilitated and simple diffusion

A modification of the method of Sen and Widdas (J. Physiol. London 160:392-403, 1962) was used to measure the rate of exit of several nonelectrolytes from erythrocytes of various species. In spite of additional errors introduced by the larger half-saturation values of the carriers (phi) and concentrations, it was possible to distinguish between systems with small values of phi, systems with relatively large values of phi, and systems involving only simple diffusion. Approximate values of phi in millimoles and of maximum transfer rate (K) in isotonic units per minute were obtained using times and initial slopes measured on experimental curves. The following values in the foregoing units were obtained: human glucose, phi = 1.8, 1.0, K = 0.8, 1.1; human glycerol, phi = 178, 94, K = 4.3, 3.3; sheep thiourea, phi = 56, 56, K = 0.9, 0.6; and rabbit glycerol, phi = 328, 64, K = 2.2, 1.0. Simple diffusion was demonstrated for the following systems: ox-ethylene glycol; ox-glycerol; sheep-ethylene glycol; and sheep glycerol.     

Multiple infection with Toxocara canis. Influence of antihistamines and corticosteroids on the histopathological response

The histopathology of the tissues of mice infected with ten doses of 100 embryonated eggs of Toxocara canis and the influence of antihistamines and corticosteroids on these findings is described. The main lesions were confined to the liver and lungs. In infected but untreated control mice hepatic lesions consisted of periportal infiltrates, widespread foci of liver cell necrosis and polymorphonuclear and mononuclear accumulation and a few fibrotic granulomata. Treatment with antihistamines did not change these findings significantly, but corticosteroids decreased the amount of cellular infiltration and the size of the lesions. Pulmonary lesions consisted mostly of confluent infiltrates of polymorphonuclears, eosinophils and mononuclear cells with some macrophage proliferation. Neither drug seemed to affect the lung involvement.     

Alteration by phosphatidyl serine of tension responses and 45Ca distribution in aortic smooth muscle

The effects of phosphatidyl serine (PS) on 45Ca distribution, 45Ca movements and contractions were examined in rabbit aortic smooth muscle. Contractile responses to submaximal concentrations of norepinephrine and histamine were potentiated by prior exposure to PS, but equivalent responses to potassium were unaffected. Addition of PS to the incubation solution decreased 45Ca uptake; exposure of aortic strips to PS during washout of either 45Ca or promethium (147Pm) resulted in maintained increases in efflux. These PS-induced alterations in net loss of 45Ca or 147Pm can be attributed to a decreased membrane reuptake and/or rebinding. However, the presence of PS during the washout significantly reduced the increases in 45Ca efflux rate elicited with either 0.05 mM concentrations of Ca++ or ethylenediamine tetraacetic acid. Thus, in rabbit aortic smooth muscle, exogenous PS can alter the availability and/or exchangeability of a membrane-bound Ca++ fraction. By specifically increasing the affinity for Ca++ at relevant membrane sites or stores. PS may enhance the ability of vascular smooth muscle to respond to stimulatory agents that mobilize Ca++ from these sites and, in this manner, potentiate contractile responses.     

Left colon gangrene after acute inferior mesenteric artery occlusion

We report here an experience with five patients, aged 58 to 70, suffering gangrene of the left colon after spontaneous inferior mesenteric artery occlusion. All cases were the result of arteriosclerosis; in two, small aortic aneurysms were present and might have been responsible for emboli to the inferior mesenteric artery. The dead bowel was resected in all patients; three patients survived. No primary anastomoses were done and they are not recommended. Because ligation of the patent inferior mesenteric artery has been done so often without ill effects during aortic surgery, the collateral circulation to the left colon can be considered excellent. Gangrene is therefore rare and requires major interference with collateral circulation by emboli or arteriosclerotic occlusion. The clinical symptoms and signs may be confusing.     

Succinylation of proteins associated with the ribosomal attachment site on microsomal membranes

Ribosome-free membranes, prepared from rat liver endoplasmic reticulum by means of 2M LiCl, lost 90% of their ability to accept ribosomes for reattachment after exposure to succinic anhydride. However, treatment of rough-surfaced endoplasmic reticulum with succinic anhydride, prior to the removal of bound ribosomes by 2M LiCl, gave rise to membranes that were still able to accept ribosomes for reattachment. Succinylation of rough-surfaced endoplasmic reticulum resulted in the removal of some loosely-bound ribosomes and also a slight loss in glucose-6-phosphatase activity. Rough-surfaced endoplasmic reticulum, preincubated with succinic anhydride prior to treatment with lithium chloride, was exposed to [3H]succinic anhydride and subsequently analysed by dodecylsulfate polyacrylamide gel electrophoresis. By this means it was found that there were at least three proteins of different molecular weights that were associated with the membrane ribosomal attachment site.     

Distraction osteogenesis for lengthening of the hard palate: Part I. A possible new treatment concept for velopharyngeal incompetence. Experimental study in dogs

Many procedures have been described to correct velopharyngeal incompetence. Significant complications can occur, and the results may not be satisfactory. If the short soft palate has satisfactory muscle function and if it could be moved toward the posterior pharyngeal wall by distraction osteogenesis of the hard palate, an entirely new concept of treatment for velopharyngeal incompetence would be available. The object of the present study was to explore the possibility of osteogenesis occurring in the hard palate in dogs after gradual distraction (callus distraction). Six adult, mix-bred dogs were anesthetized, and the palatal mucosa was elevated. A midpalatal transverse osteotomy and two lateral osteotomies were performed. Tantalum bone markers for cephalometric analysis were placed, and an individually fabricated, orthodontic-like distraction device with an expansion screw in the sagittal direction was inserted. The device was stabilized on the premolars and fixed to the palatal bone with titanium miniscrews. Gradual distraction began after a latency period of 10 to 18 days. The rate of the distraction varied from 0.25 to 0.75 mm per day. The device was left in place for 6 to 8 weeks after expansion to allow for bony consolidation. Assessment was by direct examination, cephalograms, computed tomography, and histology with bone labeling. Impressions of the jaws were taken preoperatively and after device removal to examine plaster cast changes in the dental occlusion. Cephalometric and computed tomographic scan analysis demonstrated a distraction of up to 8 mm. All gaps were filled with de novo osteogenesis. Comparison of the plaster casts revealed no change in the occlusion. At 1 month after distraction, the computed tomographic scan showed the first signs of ossification of the experimental gap from the anterior and posterior bone ends. After 4.5 months ossification was almost complete with a small translucent zone in the middle of the experimental gap. After 7 months ossification was complete.     

Preservation of protein fluorescence in embedded human dendritic cells for targeted 3D light and electron microscopy

In this study, we present a correlative microscopy workflow to combine detailed 3D fluorescence light microscopy data with ultrastructural information gained by 3D focused ion beam assisted scanning electron microscopy. The workflow is based on an optimized high pressure freezing/freeze substitution protocol that preserves good ultrastructural detail along with retaining the fluorescence signal in the resin embedded specimens. Consequently, cellular structures of interest can readily be identified and imaged by state of the art 3D confocal fluorescence microscopy and are precisely referenced with respect to an imprinted coordinate system on the surface of the resin block. This allows precise guidance of the focused ion beam assisted scanning electron microscopy and limits the volume to be imaged to the structure of interest. This, in turn, minimizes the total acquisition time necessary to conduct the time consuming ultrastructural scanning electron microscope imaging while eliminating the risk to miss parts of the target structure. We illustrate the value of this workflow for targeting virus compartments, which are formed in HIV‐pulsed mature human dendritic cells.