Ontogeny of the antigen-reactive lymph follicle-forming capacity of the popliteal lymph node in neonatal mice

The ontogenetic development of the reactive lymph follicle-forming capacity of the popliteal lymph node was investigated immunohistochemically in young mice which had received a single injection of hemocyanin (KLH) in a rear footpad at a predetermined age (between 1 and 21 days). The mice were sacrificed at various intervals after injection. In non-stimulated young mice, primary lymph follicles first appeared in the popliteal node at 11 days of age. When KLH was given to 7-day-old or older mice, each draining popliteal node showed a marked increase in B lymphocytes in the extrafollicular zone 3 days after injection and produced a number of "new" lymph follicles outside the pre-existing follicles over the next few days. In mice injected at 2-4 days of age, these nodes showed an increase in B lymphocytes in the outer cortex and had produced several lymph follicles by 8 days of age. The number of lymph follicles produced by each node tended to increase in line with age at injection. These results indicate that neonatal popliteal nodes become able to produce lymph follicles in response to exogenous antigens some time before ontogenetically developing follicles appear. The formation of new lymph follicles observed in draining popliteal nodes after KLH injection at an early postnatal age is discussed in relation to the ontogenetic development of stromal cells (precursors of follicular dendritic cells) that are capable of interacting with B lymphocytes and the extent of B lymphocyte influx into the node induced by KLH stimulation.     

Enhanced plasma ghrelin levels in rats with streptozotocin-induced diabetes

Human saliva, which contains nitrite, is normally mixed with gastric juice, which contains ascorbic acid (AA). When saliva was mixed with an acidic buffer in the presence of 0.1 mM AA, rapid nitric oxide formation and oxygen uptake were observed. The oxygen uptake was due to the oxidation of nitric oxide, which was formed by AA-dependent reduction of nitrite under acidic conditions, by molecular oxygen. A salivary component SCN⁻ enhanced the nitric oxide formation and oxygen uptake by the AA/nitrite system. The oxygen uptake by the AA/nitrite/SCN⁻ system was also observed in an acidic buffer solution. These results suggest that oxygen is normally taken up in the stomach when saliva and gastric juice are mixed.     

Inositol pyrophosphates are required for DNA hyperrecombination in protein kinase c1 mutant yeast

Diphosphoinositol pentakisphosphate (InsP(7)) and bis-diphosphoinositol tetrakisphosphate (InsP(8)) contain energetic pyrophosphate groups, occur throughout animal and plant kingdoms, and are synthesized by a recently cloned family of inositol hexakisphosphate kinases (InsP(6)Ks). We report that these inositol pyrophosphates mediate homologous DNA recombination in yeast S. cerevisae. Hyperrecombination, caused by altered protein kinase C1 (PKC1), is lost in yeast with deletion of yeast InsP(6)K (yInsP(6)K) and can be restored selectively by catalytically active yeast or mammalian InsP(6)Ks. Inositol pyrophosphates are required for two forms of hyperrecombination that differ in mechanism, suggesting some generalities for actions of inositol pyrophosphates in recombination.     

Two enzyme-linked immunosorbent assay (ELISA) systems for N1,N8-diacetylspermidine and N1,N12-diacetylspermine using monoclonal antibodies

We obtained monoclonal antibodies against N(1),N(12)-diacetylspermine (DiAcSpm) and N(1),N(8)-diacetylspermidine (DiAcSpd), and developed two systems of competitive ELISA that utilize the antibodies and a common enzyme-labeled antigen to measure these di-acetylpolyamines. Cross-reactions with N(1)-acetylspermidine in the assay of DiAcSpm and with N8-acetylspermidine in the assay of DiAcSpd were as low as 0.26 and 0.6%, respectively, and were judged to be insignificant in clinical use for measuring urinary diacetylpolyamines. These assays were used to assess diurnal variations in diacetylpolyamine excretion in urine to show that the excretion of diacetylpolyamines after normalization for the concentration of creatinine is stable over a day with only minimal diurnal variation.     

Temperature-sensitive virus derived from BHK cells persistently infected with HVJ (Sendai virus).

BHK-HVJ cells, a cell line of baby hamster kidney cells persistantly infected with HVJ (Sendai virus), started to produce infectious virus by shifting down the incubation temperature from 38 to 32 C. The virus derived from BHK-HVJ cells, designated as HJV-pB, was effectively neutralized with antibody against wild-type virus (HVJ-W) which was used for the establishment of BHK-HVJ cells. HVJ-pB replicated in eggs at 32 C, but not at 38 C, while HVJ-W grew equally well at both temperatures. When BHK cells infected with HVJ-PB were incubated at 38 C, production of infectious virus, hemagglutinin, and neuraminidase was markedly restrained, whereas a considerable amount of viral nucleocapisid and envelope antigens was detected in the cells by complement fixation tests. These viral activities became detectable immediately after temperature shift-down from 38 to 32 C even at the later stage of infection. HVJ-pB was indistinguishable from HJV-W with respect to particle size, density, and morphological characteristics, but appeared to possess a higher neuraminidase activity and was inactivated more rapidly at 50 C than HVJ-W. HVJ-pB was less cytocidal and could easily cause latent infection in BHK and mouse L cells.     

Histochemical studies of mucosubstances in metaplastic epithelium of the stomach,with special reference to the development of intestinal metaplasia

Summary Processes in the development of intestinal metaplasia of the stomach were investigated from the morphological and histochemical approaches using light and electron microscopic techniques. The specimens taken from 38 gastric carcinomas and 15 gastric and/or duodenal ulcers were subjected to this study. Morphological appearances of the intestinal metaplasia observed in routine examination with hematoxylin and eosin staining was able to be divided into complete and incomplete metaplasia by the light and electron microscopic histochemical stainings of the mucosubstances. The columnar cells at the area of the incomplete metaplasia had both the properties of the intestinal epithelia and the gastric foveolar epithelia. The incomplete as well as the complete metaplasia arose from the generative cells at the isthmus of the gland. The generative cells, however, sometimes gradually transformed to produce the complete metaplastic cells. The two processes of the development of the intestinal metaplasia were proposed and discussed.     

Simulation analysis of excitation conduction in the heart: Propagation of excitation in different tissues

The normal excitation and conduction in the heart are maintained by the coordination between the dynamics of ionic conductance of each cell and the electrical coupling between cells. To examine functional roles of these two factors, we proposed a spatially-discrete model of conduction of excitation in which the individual cells were assumed isopotential. This approximation was reasoned by comparing the apparent space constant with the measured junctional resistance between myocardial cells. We used the four reconstruction models previously reported for five kinds of myocardial cells. Coupling coefficients between adjacent cells were determined quantitatively from the apparent space constants. We first investigated to what extent the pacemaker activity of the sinoatrial node depends on the number and the coupling coefficient of its cells, by using a one-dimensional model system composed of the sinoatrial node cells and the atrial cells. Extensive computer simulation revealed the following two conditions for the pacemaker activity of the sinoatrial node. The number of the sinoatrial node cells and their coupling coefficients must be large enough to provide the atrium with the sufficient electric current flow. The number of the sinoatrial node cells must be large so that the period of the compound system is close to the intrinsic period of the sinoatrial node cell. In this simulation the same sinoatrial node cells produced action potentials of different shapes depending on where they were located in the sinoatrial node. Therefore it seems premature to classify the myocardial cells only from their waveforms obtained by electrical recordings in the compound tissue. Second, we investigated the very slow conduction in the atrioventricular node compared to, for example, the ventricle. This was assumed to be due to the inherent property of the membrane dynamics of the atrioventricular node cell, or to the small value of the coupling coefficient (weak intercellular coupling), or to the electrical load imposed on the atrioventricular node by the Purkinje fibers, because the relatively small atrioventricular node must provide the Purkinje fibers with sufficient electric current flow. Relative contributions of these three factors to the slow conduction were evaluated using the model system composed of only the atrioventricular cells or that composed of the atrioventricular and Purkinje cells. We found that the weak coupling has the strongest effect. In the model system composed of the atrioventricular cells, the propagation failure was not observed even for very small values of the coupling coefficient.(ABSTRACT TRUNCATED AT 400 WORDS)     

Three-dimensional solution structure of an archaeal FKBP with a dual function of peptidyl prolyl cis-trans isomerase and chaperone-like activities

Here we report the solution structure of an archaeal FK506-binding protein (FKBP) from a thermophilic archaeum, Methanococcus thermolithotrophicus (MtFKBP17), which has peptidyl prolyl cis-trans isomerase (PPIase) and chaperone-like activities, to reveal the structural basis for the dual function. In addition to a typical PPIase domain, a newly identified domain is formed in the flap loop by a 48-residue insert that is required for the chaperone-like activity. The new domain, called IF domain (the Insert in the Flap), is a novel-folding motif and exposes a hydrophobic surface, which we consider to play an important role in the chaperone-like activity.     

Intravesical treatment of bladder cancer with recombinant human interferon-β

Summary In order to examine its clinical efficacy, recombinant human interferon- (rIFN-) was instilled intravesically into 51 patients with superficial bladder cancer. Ten patients, who received intermittent intravesical instillation at a dose of (3–36) × 10⁶ U rIFN- on days 1–3 every week, showed no response. Thirty-two patients received intravesical instillation at a dose of (3–36) × 10⁶ U every day for 10–20 days. Eight patients showed partial response, indicating an efficacy rate of 25%. Nine patients received divided doses of 18 × 10⁶ U twice a day every day for 10–20 days. Six patients showed partial response, indicating an efficacy rate of 67%. This value was significantly higher than that obtained by administering divided doses. The response to intravesical instillation therapy with rIFN- varies with treatment protocol. Frequent and longer exposure to rIFN- may induce better regression of superficial bladder cancer. Six incidences of side-effects were found in five cases (9.8%): pollakiuria in one, pain on micturition in two, fever in two, and eruption in one case. All of these side-effects were slight and reversible after drug withdrawal. Laboratory tests showed only a few changes with low severity. Thus, rIFN- is potentially a new drug for instillation therapy of superficial bladder cancer, in view of the absence of adverse effects.     

Frequency of micronuclei in hepatocytes following X and fast-neutron irradiations--an analysis by a linear-quadratic model

The usefulness of the micronucleus assay for investigating the radiation response of hepatocytes was examined. The frequency was defined as the ratio of the total number of micronuclei to the number of hepatocytes examined. The dose-response curves were curvilinear after X rays and linear after neutrons. These dose-response curves were analyzed by a linear-quadratic model, frequency = aD + bD2 + c. The a/b ratio was 3.03 +/- 1.26 Gy following X irradiation. This value is within the range of the alpha/beta ratios reported by others using the clonogenic assay of hepatocytes. While the a/b value for neutrons was 24.3 +/- 11.7 Gy, the maximum relative biological effectiveness of neutrons was 6.30 +/- 2.53. Since the micronucleus assay is simple and rapid, it may be a good tool for evaluating the radiation response of hepatocytes in vivo.