Amino acids in the medulla oblongata contribute to baroreflex modulation by angiotensin II

We investigated the underlying mechanisms of baroreflex alteration produced by intravenous angiotensin II (ANG II) by monitoring the release of amino acids from the rostral ventrolateral medulla (VLM) using a brain microdialysis technique. Reflex changes in heart rate were elicited by bolus intravenous injection of phenylephrine (2–40 μg/kg) before and 120 min after the initiation of administration of a subpressor dose of ANG II (5.4 pmoVkg/min) or vehicle. The slope of the regression line obtained from changes in mean arterial pressure and heart rate elicited by phenylephrine was used as an Index of baroreceptor reflex sensitivity. ANG II administration for 120 min significantly attenuated the baroreflex sensitivity (from -0.59 ± 0.10 to -0.30 ± 0.08 bpm/mmHg). This attenuation was accompanied with an increase in the release of glutamate and glycine from the VLM (+40% and +20%, respectively) at 120 min. Glycine perfusion into this area resulted in an attenuation of baroreflex sensitivity with a magnitude similar to that obtained with infusion of a subpressor dose of ANG II, whereas glutamate perfusion caused a resetting of baroreflex. These results suggest that glycine and glutamate are involved in cardiovascular regulation in the VLM. Furthermore, the augmented releases of these amino acids may account for the underlying mechanism of ANG II-induced attenuation of baroreflex function.     

Estimation of detection limit from slope of B/B0 in competitive ELISA

A method has been proposed for determining the detection limit (L(D)) from the slope of a semilogarithmic plot of a B/B(0) curve in competitive enzyme linked immunosorbent assay (ELISA). As an application, this paper describes a graphic determination of L(D) from analogue data in the literature. The L(D) obtained corresponds to the concentration at which the relative standard deviation of concentration estimates is 30%.     

Combined mediastinal node assessment by lymphadenectomy and intraoperative mediastinoscopy

The purpose of this study was to determine the importance of combined mediastinal node assessment by lymphadenectomy and intraoperative mediastinoscopy to patients with left lung cancer. Forty-one patients with left lung cancer were divided into a group of 13 and a group of 28: in the first group, the aortic arch was mobilized, while in the second group the aortic arch was not mobilized. The mediastinal nodes of both groups were then dissected and mediastinoscopes were inserted into the operation field with an approach through thoracotomy to biopsy each mediastinal node. We compared nodal pathological assessment in these two groups. In the group with mobilized aortic arches, pathological assessment of lymphadenectomy at Naruke's station 3 was 11/13 (85%) and combined with intraoperative mediastinoscopy was 12/13 (92%). In the group without mobilized aortic arches, pathological assessment of lymphadenectomy of station 3 was 14/28 (50%) and combined use of intraoperative mediastinoscopy significantly improved the diagnoses to 24/28 (86%) (P=0.004). Combined use of lymphadenectomy and intraoperative mediastinoscopy could improve the assessment of station 3 in left lung cancer without mobilizing aortic arch.     

Effectiveness of intragastric immunization with protein and oligodeoxynucleotides containing a CpG motif for inducing a gastrointestinal mucosal immune response in mice

PURPOSE: To investigate a new modality of mucosal vaccines, we evaluated the effectiveness of intragastric immunization for inducing a mucosal immune response in the gastrointestinal tract. METHODS: Mice were immunized with beta-galactosidase (beta-gal) and synthesized oligodeoxynucleotides containing a CpG motif (CpG-DNA) by intragastric injection, and the immune response was compared with those induced by 3 other immunization forms: intranasal, oral, and intradermal. RESULTS: Intragastric immunization with beta-gal and CpG-DNA induced significant anti-beta-gal fecal IgA production at 2 weeks; however, at 4 weeks the response was lacking. In contrast, intranasal immunization with beta-gal and CpG-DNA induced the highest anti-beta-gal fecal IgA production at 4 weeks. CONCLUSION: Although intragastric immunization with protein and CpG-DNA induces a mucosal immune response in the gastrointestinal tract, intranasal immunization is the most effective to induce both mucosal and systemic immune responses. This finding may increase the possibility for developing vaccines against mucosal pathogens, especially Helicobacter pylori.     

Changes in distribution of hepatic blood flow induced by intra-arterial infusion of angiotensin II in human hepatic cancer

Changes in the distribution of the hepatic blood flow induced by intra-arterial infusion of angiotensin II (AT-II) were studied in human hepatic cancers using extremely short-lived radioisotope (RI) (krypton 81 m [81mKr]; half-life, 13 seconds). After the start of continuous infusion of AT-II, the radioactivity of the tumor showed about a two-fold increase, whereas that of the nontumor region decreased to about one half as much as the level before the infusion. Consequently, the mean ratio of the arterial blood flow in the tumor region to that in the nontumor region (T/N ratio) increased to 3.30 (P less than 0.001). The T/N ratio showed a peak before the peripheral blood pressure reached the maximum, and thereafter tended to decrease. Intra-arterial infusion of AT-II raised the T/N ratio more obviously than did intravenous infusion of the drug, with less rise in the peripheral blood pressure. It is believed that intra-arterial infusion chemotherapy with local use of AT-II enables better accessibility of chemotherapeutic drugs to tumors.     

Assessment of contrast enhancement using the variable contrast medium injection method in 3D-CTA of the head

We have reported that, using the bolus-tracking method synchronized with an injector, the injection of contrast medium in a single phase up to 10 sec before the end of the study (referred to as "single-stage injection") or the combination of single-stage injection stopped 15 sec before the end of the study and a physiological saline solution flush (referred to as "saline solution flush") makes it possible to minimize the amount of contrast medium employed in 3D-CTA of the head and neck in a scanning time of approximately 30 sec. If the continuous variable method of contrast medium injection (referred to as "variable injection") can provide the same level of contrast enhancement as that obtained with a single-stage injector for constant-rate injection, it should be possible to eliminate cumbersome study procedures associated with the saline solution flush and to simplify the study protocol. We therefore performed a comparative study to assess the contrast enhancement effect in variable injection. The results showed that variable injection provided almost the same degree of contrast enhancement as single-stage injection + saline solution flush, while permitting the amount of contrast medium to be reduced. It was concluded that variable injection (with a variation parameter of 0.5) is an effective method of improving the contrast enhancement effect and minimizing the amount of contrast medium employed, as compared with the saline solution flush method. Furthermore, it permits the examination procedures to be simplified.     

Primary repair of posterior cruciate ligament avulsion fracture: the effect of occult injury in the midsubstance on postoperative instability

BACKGROUND: In the posterior cruciate ligament avulsion fracture, posterior instability cannot be completely restored by the anatomical reduction and fixation of an avulsed fragment. HYPOTHESIS: The occult midsubstance injury inside the posterior cruciate ligament may affect the residual posterior instability after anatomical reduction and internal fixation of the avulsed fragment. STUDY DESIGN: Prospective comparative clinical study. METHODS: Thirty-one patients were followed for a period of 2 to 8 years. Based on magnetic resonance images taken immediately after the injury, these patients were divided into 2 groups, the occult injury group (group O, 15 knees) and the uninjured group (group N, 16 knees). RESULTS: The side-to-side difference of the posterior knee instability was 3.2 mm in group O and 3.0 mm in group N. Approximately 60% of the knees examined showed mild posterior instability in both groups. There were no significant differences found between the 2 groups. CONCLUSION: The occult posterior cruciate ligament midsubstance injury does not significantly affect postoperative posterior instability of the knee. This fact did not support the hypothesis that has been commonly considered thus far. CLINICAL RELEVANCE: It is not necessary for orthopaedic surgeons to be overly apprehensive about occult midsubstance injury in the treatment of posterior cruciate ligament avulsion fracture.     

Expression of dentin matrix protein 1 (DMP1) in nonmineralized tissues

Dentin matrix protein 1 (DMP1) is an Arg-Gly-Asp-containing acidic phosphoprotein that was originally identified from a rat incisor cDNA library and was thought to be a dentin-specific protein. DMP1 was later shown to express in a number of hard tissue-forming cells, including osteoblasts, osteocytes, ameloblasts, and cementoblasts, and was considered to play important roles in mineralization. Further, DMP1 gene expression was also detected in fetal bovine brain and in newborn mouse brain. These findings indicate the possibility of DMP1 expression in other soft tissues. In the present study, to clarify the significance of DMP1 expression in nonmineralized tissues, we made a specific antibody to mouse DMP1 peptides and demonstrated that DMP1 protein was localized in mouse brain, pancreas, and kidney by immunohistochemistry. Further DMP1 mRNA was detected in nonmineralized mouse tissues including liver, muscle, brain, pancreas, and kidney by RT-PCR. Based on the evidence that the localization and the expression of DMP1 are not restricted to mineralized tissues, we assume that DMP1 may have functions other than the regulation of mineralization.