Genetic susceptibility to herpetic encephalitis of inbred rabbits of B/Jas strain

Inbred rabbits of B/Jas strain were found to be highly susceptible to herpes simplex virus type 1 encephalitis, following i.v. injection of the virus, while Chbb:HM strain rabbits were not susceptible. The susceptibility trait seemed to be inherited recessively, involving multiple genes, because (B/Jas x Chbb:HM)Fl hybrids were as resistant as Chbb:HM rabbits, and because more than 90% of backcrosses of (B/Jas x Chbb: HM)FI to B/Jas were resistant to viral inoculation. The encephalitis in B/Jas rabbits resembled human herpes simplex encephalitis, in that the temporal lobe as well as the brain stem were affected preferentially, leading to the development of various types of seizures, such as circling, loss of balance leading to a fall, and tonic and clonic convulsions. The disease could be diagnosed by magnetic resonance imaging (MRI) analysis before onset of seizures, and diseased rabbits showed a marked lymphopenia at onset of seizures. © 1995 Wiley-Liss, Inc.     

Assessment of proton nuclear magnetic resonance spectroscopy for detection of malignancy

Water-suppressed proton nuclear magnetic resonance spectra were generated (by using 360 and 500 MHz systems) from human plasma and serum samples taken from 35 apparently healthy individuals, 52 patients with overt malignancies, and 37 patients with hypertriglyceridemia (triglycerides greater than 200 mg/dL or 2.26 mmol/L). The line widths from the lipoprotein-lipid methylene and methyl resonances at approximately 1.3 and 0.9 ppm were averaged by the method of Fossel et al. (N Engl J Med 1986;315:1369-76), but, contrary to their findings, we were unable to distinguish normal individuals from those with malignant tumors (e.g., mean +/- SD line width at 360 MHz: normal group = 32.9 +/- 3.6 Hz, malignant group = 28.3 +/- 4.9 Hz). The average line-width measurements (y), however, varied with the triglyceride content (x, mg/dL) of the plasma or serum as follows (logarithmic transformation of the data determined at 360 MHz and regression analysis): y = 110 (x-0.27). Data from both nonmalignant and malignant specimens fit this equation, the coefficient of correlation being -0.91. These findings suggest that considerable caution should be used in interpreting water-suppressed proton NMR spectra for cancer detection.     

Deuterium chemical shift imaging for the estimation of cerebral perfusion in rabbit infarction model

In order to develop a new technique for the measurement of local cerebral blood flow (CBF), the deuterium chemical shift imaging (²H-CSI) technique, an application of in vivo nuclear magnetic resonance (NMR), was used for the estimation of cerebral perfusion in rabbit infarction model. The ²H chemical shift images of rabbit brain were obtained every 30 seconds before and after intravenous injection of deuterated saline. The changes in ²H NMR signal intensity documented that the cerebral perfusion in the damaged area due to infarction decreased obviously compared to that in the intact area. These findings indicate that the ²H-CSI technique can be applied to the measurement of local CBF. The readily availability and limited toxicity of deuterated water may make possible to use this method in clinical cases.(Kito K, Arai T, Mori K, et al.: Deuterium chemical shift imaging for the estimation of cerebral perfusion in rabbit infarction model. J Anesth 7: 447–453, 1993)     

Enzyme histochemistry is useful to assess viability of tumor tissue after microwave coagulation therapy (MCT): metastatic adenocarcinoma treated by lateral segmentectomy after MCT

We report on a case of metastatic adenocarcinoma of liver that was removed and examined histochemically after microwave coagulation therapy (MCT). The patient was a 65-year-old woman who had a metastatic tumor in the liver (S3) after high anterior resection due to a rectal adenocarcinoma and received MCT against the tumor. One month after MCT, multiple metastatic tumors were detected by abdominal computed tomography (CT) scan. As it was difficult to control them by MCT alone, we performed lateral segmentectomy. To assess the effects of microwave ablation on cellular viability of metastatic tumor, we used enzyme histochemistry for acid phosphatase (AcP), which is positive in macrophages infiltrating in the tumor. In a part of the ablated area of resected liver, there was remaining neoplastic tissue of which the morphology was maintained in H&E staining. This was found to be microwave-fixed non-viable tissue because no enzyme activity of AcP was detected in the infiltrating macrophages. This case report suggests that enzyme histochemistry was useful to assess the effect of MCT, enabling us to distinguish fixed cells from viable cells.     

Orally Administered Liposomal Lactoferrin Inhibits Inflammation‐Related Bone Breakdown Without Interrupting Orthodontic Tooth Movement

Background: Bovine lactoferrin (bLF) modulates the production of tumor necrosis factor‐alpha (TNF‐α) and inhibits alveolar bone breakdown associated with periodontitis. This study is designed to examine the effects of orally administered liposomal bLF (LbLF) on orthodontic force (OF)‐induced alveolar bone remodeling during experimental tooth movement. Methods: Two groups of male Wistar rats were treated with either LbLF or control solution in drinking water 7 days before OF application. Lipopolysaccharide (LPS) was injected into the gingival sulcus in half the rats in each group. Thus, four groups: OF, OF+LbLF, OF+LPS, and OF+LPS+LbLF were established. Results: Orally administered LbLF significantly reduced apical migration of junctional epithelium in the OF and OF+LPS groups. In OF+LPS, osteoclast number in the alveolar crestal area was increased by LPS treatment, whereas osteoclast number was significantly reduced in OF+LPS+LbLF through suppression of TNF‐α production. Osteoclastic induction in the middle part, mainly from OF application, was not affected by LbLF administration. Inhibition of tooth movement was not induced by LbLF. Conclusions: Orally administered LbLF significantly inhibits LPS‐induced alveolar bone resorption but not OF‐induced bone remodeling. LbLF could be a potent therapeutic and preventive agent to control periodontal inflammation in patients undergoing orthodontic treatment.     

Observation of femtosecond X-ray interactions with matter using an X-ray–X-ray pump–probe scheme

Resolution in the X-ray structure determination of noncrystalline samples has been limited to several tens of nanometers, because deep X-ray irradiation required for enhanced resolution causes radiation damage to samples. However, theoretical studies predict that the femtosecond (fs) durations of X-ray free-electron laser (XFEL) pulses make it possible to record scattering signals before the initiation of X-ray damage processes; thus, an ultraintense X-ray beam can be used beyond the conventional limit of radiation dose. Here, we verify this scenario by directly observing femtosecond X-ray damage processes in diamond irradiated with extraordinarily intense (∼10¹⁹ W/cm²) XFEL pulses. An X-ray pump–probe diffraction scheme was developed in this study; tightly focused double–5-fs XFEL pulses with time separations ranging from sub-fs to 80 fs were used to excite (i.e., pump) the diamond and characterize (i.e., probe) the temporal changes of the crystalline structures through Bragg reflection. It was found that the pump and probe diffraction intensities remain almost constant for shorter time separations of the double pulse, whereas the probe diffraction intensities decreased after 20 fs following pump pulse irradiation due to the X-ray–induced atomic displacement. This result indicates that sub-10-fs XFEL pulses enable conductions of damageless structural determinations and supports the validity of the theoretical predictions of ultraintense X-ray–matter interactions. The X-ray pump–probe scheme demonstrated here would be effective for understanding ultraintense X-ray–matter interactions, which will greatly stimulate advanced XFEL applications, such as atomic structure determination of a single molecule and generation of exotic matters with high energy densities.Since W. C. Röntgen discovered X-rays emitted from vacuum tube equipment in 1895, scientists have continuously endeavored to develop brighter X-ray sources throughout the 20th century. One of the most remarkable breakthroughs was the emergence of synchrotron light sources, which were much more brilliant than the early lab-based X-ray sources. Such dramatic increase in X-ray brilliance provided a pathway to obtain high-quality X-ray scattering data. This, in turn, enabled one to solve the structures of complex systems such as proteins, functional units of living organisms, and viruses. However, the increase in the brilliance is also accompanied by a severe problem of X-ray radiation damage to the samples being examined (1). X-rays ionize atoms and generate highly activated radicals that break chemical bonds and cause changes in the structures of the samples. To achieve structure determination precisely, a sufficient scattering signal should be recorded before the samples are severely damaged. Radiation damage was considered to be an intrinsic problem associated with X-ray scattering experiments, which imposed a fundamental limit on the resolution in X-ray structure determination (2).The recent advent of X-ray free-electron lasers (XFELs) (3–5), which emit ultraintense X-ray pulses with durations of several femtoseconds, may totally avoid the problem of radiation damage. The irradiation of intense XFEL pulses generates highly ionized atoms, and the strong Coulomb repulsive force leads to evaporation of the samples. Meanwhile, it has been predicted theoretically (6) that atoms do not change their positions before the termination of the femtosecond X-ray pulse owing to inertia, thus enabling the use of X-ray radiations beyond the conventional X-ray dose limit. This innovative concept, called a “diffraction-before-destruction” scheme (6, 7), has paved a clear way to high-resolution structure determinations of weak scattering objects, including nanometer-sized protein crystals (8), noncrystalline biological particles (9), and damage-sensitive protein crystals (10).Despite the potential impact of XFELs, detailed understanding of the ultrafast XFEL damage processes has been missing. As a pioneering work, Barty et al. (11) measured the diffraction intensities of protein nanocrystals by changing the XFEL pulse durations from 70 to 300 fs at intensities of ∼10¹⁷ W/cm². They found that the diffraction intensities greatly decrease for longer durations, clearly indicating sign of structural damage, i.e., X-ray–induced atomic displacements within the XFEL pulse durations. For further understanding of ultraintense X-ray interactions with matter, we need to directly measure the temporal changes of the structural damage. In particular, measuring the ignition time of the atomic displacements is crucial for realizing advanced applications with greatly intense XFELs. Although improving our knowledge of the X-ray damage processes is essential for all aspects of XFEL science, the experimental verifications have been missing because of the extreme difficulty in observation with ultrahigh resolutions in space (ångstrom) and time (femtosecond).As a new approach to investigate the femtosecond X-ray damage processes, we here propose an X-ray–X-ray pump–probe experiment using double X-ray pulses; a pump X-ray pulse excites a sample and a probe X-ray pulse with a well-controlled time delay characterizes the change in the sample. In this approach, it is highly useful to exploit two-color double pulses with tunable temporal separations (12–15), which have been developed at SPring-8 Angstrom Compact free-electron LAser (SACLA) (4) and Linac Coherent Light Source (3). In this article, we measured the X-ray damage processes of diamond by using an X-ray–X-ray pump–probe diffraction experiment at SACLA. As the carbon–carbon bond is one of the most fundamental bonds in biomolecules, our results should provide a benchmark for XFEL-induced damage to practical samples.     

Positron emission tomography reporter gene imaging in the myocardium: for monitoring of angiogenic gene therapy in ischemic heart disease

Cardiac angiogenic gene therapy has emerged as a novel treatment approach for patients with intractable ischemic heart disease, aiming at facilitating neovascularization to augment blood flow in the ischemic myocardium by introducing genes encoding for angiogenic factors. While several clinical trials for cardiac angiogenic gene therapy are currently in progress, there remains a discrepancy between impressive preclinical results and their limited clinical findings. On the other hand, positron emission tomography (PET) reporter gene imaging has been developed to monitor expression of transgenes in vivo. PET reporter genes encode for proteins that retain complementary positron-emitting tracers (PET reporter probes), and theoretically any therapeutic gene can be linked and coexpressed with an appropriate PET reporter gene. Consequently, PET reporter gene imaging with a PET reporter probe affords external determination of the location, magnitude, and duration of expression of therapeutic genes noninvasively. Since PET imaging can be performed in various species ranging from mice to humans, in vivo cardiac PET reporter gene imaging could play a critical role in identifying the "missing link" as a powerful translational research tool. In this article, we discuss the role of PET reporter gene imaging in basic and clinical research on cardiac angiogenic gene therapy.