Invasive Streptococcus agalactiae (group B streptococcus) infection with toxic shock-like syndrome: A report of a fatal non-pregnant case and a review of the literature

Streptococcus agalactiae (group B streptococcus; GBS) is a Gram-positive coccus. It has emerged as a cause of significant infections in non-pregnant adults, particularly neonates and individuals aged 65 years or older, which can lead to fatal outcomes. Streptococcal toxic shock-like syndrome (STSS) is an acute illness, which is mainly caused by exotoxin-producing strains of Streptococcus pyogenes and may result in death. In this report, we present a fatal non-pregnant case of STSS induced by GBS in a 45-year-old healthy female. The patient presented with fever, polyarthralgia, myalgia, and skin erythema. Matrix Assisted Laser Desorption/Ionization‒Time of Flight Mass Spectrometry (MALDI-TOF-MS) and PCR identified GBS in colonies from her blood and urine cultures, and she was diagnosed with septicemia and STSS. On the sixth day of her illness, she died from acute respiratory distress syndrome and multiple organ dysfunction syndrome. Whole-genome sequencing revealed the presence of several virulence genes in the genome of the GBS strain detected in the blood cultures, which may have contributed to the development of STSS and the patient's death.

An incidentally discovered paraganglioma that caused sinus arrest after resection

Paragangliomas are neural-crest-derived nonepithelial neuroendocrine tumors distributed along the parasympathetic and sympathetic nerves. To our knowledge, no studies were reported regarding sinus arrest on day 4 after paraganglioma resection. A 66-year-old female patient with a history of pulmonary vein isolation visited our department for sigmoid colon cancer treatment. Enhanced computed tomography revealed an enhanced small nodule-like lymph node near the root of the inferior mesenteric artery. The patient underwent laparoscopic colectomy with regional lymph node dissection. Postoperatively, paroxysmal atrial fibrillation attacks developed, and the patient resumed oral medication. Additionally, sinus arrest after tachycardia developed. Changing the oral medication could maintain her circulatory dynamics. Pathological examination revealed that differentiated tubular adenocarcinoma infiltrated the submucosa. Immunohistochemically, the excised nodule as a lymph node was considered a functional paraganglioma. Our case indicates that paraganglioma resection and oral medication resumption may contribute to sinus arrest. When arrhythmias affecting the circulation occur perioperatively, the presence of a catecholamine-producing tumor should be considered in addition to cardiac disease. J. Med. Invest. 70 : 503-507, August, 2023.

Intra-familial transmission of Streptococcus dysgalactiae subsp. equisimilis (SDSE): A first case report and review of the literature

BACKGROUND

Concern about Streptococcus dysgalactiae infections has been increasing worldwide, and many cases of invasive infections have been reported. Streptococcus dysgalactiae has two main subspecies: S. dysgalactiae subsp. equisimilis (SDSE) and S. dysgalactiae subsp. dysgalactiae (SDSD). The epidemiology of invasive SDSE infections is not well understood, and the exact numbers of human SDSE infections are not known because standard laboratories are not able to identify Lancefield group C streptococci (GCS) or group G streptococci (GGS) to the species level. SDSE is often present in skin lesions, and sites of SDSE colonization and focal SDSE infections serve as the principal reservoirs for the transmission of skin and soft-tissue infections. Although the person-to-person transmission of S. pyogenes infections has been reported, the intra-familial transmission of SDSE has not been reported.

CASE PRESENTATION

We report two cases of cellulitis with bacteremia in a family. A 72-year-old female with cellulitis in her right lower extremity was hospitalized, and a 104-year-old male relative was hospitalized with cellulitis 2 days later. Two strains of Streptococcus dysgalactiae subsp. equisimilis were isolated from the blood of the patients. Single nucleotide polymorphism analysis of the bacterial genomes suggested that the two strains had the same origin. This is the first case report about the intra-familial transmission of Streptococcus dysgalactiae subsp. equisimilis.

CONCLUSIONS

This is the first case report about the intra-familial transmission of Streptococcus dysgalactiae subsp. equisimilis.

Morphological and genetic identification of fungal genus/species in formalin-fixed, paraffin-embedded specimens obtained from patients with histologically proven fungal infection

BACKGROUND

Although fungi are found relatively easily by microscopic examination of pathological samples, identification of fungal genus and species in pathological samples is not easy because the morphological features of fungi are similar among genera and species.

OBJECTIVES

A multiple real-time PCR was developed for identification of fungal genus/species, and morphological characterizations of fungi were analysed in pathological samples.

PATIENTS/METHODS

Seventy-five formalin-fixed paraffin-embedded (FFPE) samples morphologically proven to contain any fungus were examined. A multiple real-time PCR system was developed to identify 25 fungal genus/species in pathological samples. Morphology of fungus in the specimens was re-reviewed retrospectively based on the results of real-time PCR.

RESULTS

Real-time PCR identified fungal genus/species in 56 of 75 (74.6%) specimens with histologically proven fungal infection. In 53 specimens of filamentous fungi, Aspergillus spp. (22 specimens), Cladosporium (8), Scedosporium apiospermum (4), Malassezia sympodialis (1) and Candida albicans (1) were identified. Pseudohyphae of Candida were confused with filamentous fungus in a case. Morphological observation suggested differences in the presence of septated or non-septated hyphae, the filament size, and the branch angle among genus/species of filamentous fungi; however, genus/species was not able to be determined by their morphological features. In 22 specimens of yeasts, real-time PCR allowed for the identification of Candida albicans (12 specimens), Candida glabrata (2), Cladosporium (2), Scedosporium apiospermum (2), Pichia kudriavzevii (1) and Aspergillus sydowii (1).

CONCLUSIONS

These data suggest that it is difficult to identify fungal genus/species by morphological features alone. Real-time PCR is useful to identify fungal genus/species in pathological samples.

A case of protein-losing gastroenteropathy caused by systemic AA amyloidosis secondary to undifferentiated carcinoma of unknown primary origin

We report the case of a 61-year-old woman with Kartagener syndrome who presented with a 3-month history of chronic watery diarrhoea and severe hypoalbuminaemia. Histopathological examination of duodenum and large intestine biopsies showed amyloid A (AA) amyloid deposition. Scintigraphy and alpha-1 anti-trypsin clearance evaluations revealed protein-losing gastroenteropathy. Computed tomography with contrast and positron emission tomography showed a pelvic mass with multiple para-aortic lymph node enlargement. We suspected protein-losing gastroenteropathy secondary to AA amyloid produced related to malignant tumours. Following tumour resection, histopathological examination of the lesion revealed undifferentiated carcinoma of unknown origin. Postoperatively, the patient’s nutritional condition improved. There has been no recurrence of protein-losing gastroenteropathy 6 months postoperatively. This is the first report of protein-losing gastroenteropathy and AA amyloidosis secondary to undifferentiated carcinoma. Early recognition and intervention could increase the likelihood of amyloidosis remission.

Estimation of Arterial Mechanical Properties from Aortic and Tonometric Arterial Pressure Waveforms

Although arterial mechanical properties have been evaluated using arterial input impedance, the relative difficulty in accurate flow measurement made the value of impedance somewhat limited. To develop an alternative method to evaluate arterial mechanical properties, we analyzed the aortic pressure (AoP)-radial arterial pressure (RAP) relationship because of relative ease in obtaining peripheral pressure waveform by tonometry. In 8 patients we simultaneously recorded aortic root and radial arterial pressure waveforms. We calculated the transfer function from AoP to RAP. We then fitted the transfer function to a model of a lossless uniform elastic tube terminated with a modified Windkessel model. The fact that the model transfer function predicted AoP from RAP waveform with considerable accuracy indicated that the model represented the arterial mechanical properties well. We conclude that we can estimate the arterial mechanical properties by the pressure-pressure transfer function analysis.

Calcified Amorphous Tumor-Induced Acute Cerebral Infarction

We report the case of a 38-year-old woman who was admitted for acute cerebral infarction linked to a cardiac calcified amorphous tumor (CAT) and related mitral annular calcification (MAC). The cardiac mass was removed, and mitral valve replacement surgery was performed. Pathological examination revealed an amorphous accumulation of degenerating material within both lesions, indicating that build-up of calcium along the mitral annulus and subsequent rupture of the fibrotic tissue may be involved in the initiation and progression of CAT.

Mycotic pseudoaneurysm of a pulmonary artery branch caused by Cladosporium

We report the case of a 53-year-old male with a history of acute myelogenous leukemia, who suffered the rupturing of a right-sided pulmonary artery pseudoaneurysm combined with pneumonia. He underwent a right-sided lower lobectomy. The resected lung tissue demonstrated a mycotic pseudoaneurysm of a pulmonary artery branch together with a filamentous fungal infection. Pseudoaneurysms are caused by the breaching of all layers of a blood vessel wall. The extravasated blood is trapped by the surrounding extravascular tissue or clots. Cladosporium was detected during a polymerase chain reaction-based analysis followed by DNA sequencing of formalin-fixed paraffin-embedded lung tissue samples. Although previous cases of pulmonary artery pseudoaneurysms caused by fungal infections, e.g., Candida or Aspergillus sp., have been reported, to the best of our knowledge this is the first case to involve cladosporiosis.

Conserved sequences of BART and BHRF regions encoding viral microRNAs in Epstein-Barr virus-associated lymphoma

Objective

Epstein-Barr virus (EBV) encodes at least 25 pri-microRNAs (miRNAs) in two regions of its DNA genome, BART and BHRF. B95-8, an EBV reference strain, has a deletion in the BART region. However, no information is available on the deletions or mutations in the BART and BHRF regions in clinical samples of EBV-associated lymphoma.

Results

Nine DNA fragments encoding miR-BARTs and two coding miR-BHRF1s were amplified by PCR from DNA samples extracted from 16 cases of EBV-associated lymphoma. All the PCR products were sequenced directly. DNA fragments encoding miR-BARTs and miR-BHRF1-1 were successfully amplified from all samples. An adenine-to-guanine mutation in the DNA fragment encoding miR-BART2-3p was detected in four of the 16 cases, and a cytosine-to-thymidine mutation in the DNA fragment encoding miR-BART11-3p was detected in one of the 16 samples. These mutations were not associated with any histological categories of lymphoma. In conclusion, mutations were rarely observed in the DNA encoding viral miRNAs in cases of lymphoma. This suggests that the DNA sequences of EBV-encoded miR-BARTs and miR-BHRF1-1 are conserved in EBV-associated lymphoma.

Post-mortem detection of bacteremia using pairs of blood culture samples

AIM

The objective of this study was to assess the utility of examining pairs of blood culture samples obtained from separate sites (both ventricles or the aorta and vena cava) for detecting bacteremia in the post-mortem setting.

METHODS

Autopsy cases in which bacterial species were isolated from blood cultures were identified over a 4-year period. Ante-mortem and post-mortem records and the findings of pathological examinations were reviewed.

RESULTS

Overall, 23 bacterial species were detected in 18 autopsy cases. E. coli was the most commonly detected species (5 cases, 27.8%), followed by S. aureus and K. pneumoniae, respectively. Seven of the detected bacterial species (3 cases, 16.7%) were obligate anaerobes (Clostridium spp. and Bacteroides spp.). Among the 3 cases involving obligate anaerobes, multiple bacterial species were detected in 2 cases. Clinically, 2 of the 18 patients in which bacteria were detected were treated for significant infections (urosepsis, pneumonia, and catheter-related bloodstream infection) before their deaths. Seven cases exhibited evidence of significant infection during the post-mortem pathological examination. The differences between the aerobic and anaerobic bacteria positivity rates of the single and paired blood culture samples were significant (aerobic: p=0.013 and anaerobic: p=0.018).

CONCLUSION

Analyzing pairs of blood culture samples obtained from separate sites is useful for detecting bacteremia during post-mortem examinations.

Translational neurocardiology: preclinical models and cardioneural integrative aspects

Neuronal elements distributed throughout the cardiac nervous system, from the level of the insular cortex to the intrinsic cardiac nervous system, are in constant communication with one another to ensure that cardiac output matches the dynamic process of regional blood flow demand. Neural elements in their various 'levels' become differentially recruited in the transduction of sensory inputs arising from the heart, major vessels, other visceral organs and somatic structures to optimize neuronal coordination of regional cardiac function. This White Paper will review the relevant aspects of the structural and functional organization for autonomic control of the heart in normal conditions, how these systems remodel/adapt during cardiac disease, and finally how such knowledge can be leveraged in the evolving realm of autonomic regulation therapy for cardiac therapeutics.

Exercise training plus calorie restriction causes synergistic protection against cognitive decline via up-regulation of BDNF in hippocampus of stroke-prone hypertensive rats

One of the important organ damage of hypertension is cognitive decline. Cognitive function is determined by the function of hippocampus, and previous studies have suggested that the decrease in brain-derived neurotrophic factor (BDNF) in the hippocampus causes cognitive decline. Protection against cognitive decline is reported not only in pharmacological therapy but also in exercise training or calorie restriction. The aim of the present study was to determine whether exercise training plus calorie restriction cause synergistic protection against cognitive decline via BDNF in the hippocampus or not. Exercise training for 28 days improved cognitive decline determined by Morris water maze test via up-regulation of BDNF in the hippocampus of stroke-prone spontaneously hypertensive rats, whereas calorie restriction for 28 days did not. However, exercise training plus calorie restriction causes the protection against cognitive decline to a greater extent than exercise training alone. In conclusion, exercise training plus calorie restriction causes synergistic protection against cognitive decline via up-regulation of BDNF in the hippocampus of stroke-prone hypertensive rats.

Intravascular parasympathetic cardiac nerve stimulation prevents ventricular arrhythmias during acute myocardial ischemia

Although previous animal studies clearly demonstrated antiarrhythmic effects of vagal stimulation during acute myocardial ischemia, highly invasive nature of vagal stimulation limited its clinical use. Recently, intravascular parasympathetic cardiac nerve stimulation (IPS) has emerged as a novel approach to the cardiac autonomic nervous system. We hypothesized that IPS might prevent ventricular arrhythmias during acute myocardial ischemia.

METHODS

The IPS (36 V, 10 Hz) was performed in superior vena cava using an expandable electrode-basket catheter. In 18 open-chest dogs, left anterior descending coronary artery ligation was performed without IPS (control group, n= 6), with IPS (IPS group, n= 6) and with IPS and right atrial pacing at 180/min (IPS+P group, n=6). The ECGs were monitored for 60 min. The incidence and severity of ventricular arrhythmias were analyzed.

RESULTS

The IPS significantly decreased the frequency of premature ventricular contractions (control group: 9.1 &#177; 4.6/min, IPS group: 0.2 &#177; 0.4 /min, IPS+P group: 10.6 &#177; 4.2 / min; p&lt;0.05). The frequency of ventricular tachycardia was lower in IPS group (0 &#177; 0 /min) than in control group (0.15 &#177; 0.18 /min, p&lt;0.05) and than in IPS+P group (0.17 &#177; 0.12 /min, p<0.05). The incidence of ventricular fibrillation was lower in IPS group (0%) than in control group (33.3%) and than in IPS+P group (33.3%).

CONCLUSIONS

The IPS suppressed ventricular arrhythmias during acute ischemia mainly through its bradycardiac effect.

Experimental 'jet lag' causes sympathoexcitation via oxidative stress through AT1 receptor in the brainstem

Circadian disruptions through frequent transmeridian travel, rotating shift work, and poor sleep hygiene are associated with an array of physical and mental health maladies, including the abnormal autonomic nervous system. We have demonstrated that the oxidative stress through AT(1) receptor in the brain activates sympathetic nervous system. The aim of the present study was to determine whether experimental 'jet lag' causes sympathoexcitation via oxidative stress through AT(1) receptor in the cardiovascular center of the brainstem (rostral ventrolateral medulla; RVLM) or not. Experimental 'jet lag' was made to normotensive (Wister-Kyoto rat; WKY rat) and hypertensive rats (stroke-prone spontaneously hypertensive rats; SHRSP) by the exposure to a 12 hour phase advance for 5 days. In WKY, 'jet lag' increases blood pressure and the activity of sympathetic nervous system via oxidative stress through angiotensin II type 1 receptor in the RVLM for 2 days only, and the changes are improved at 3 day after the initiation of 'jet lag'. In SHRSP, 'jet lag' also increases blood pressure and the activity of sympathetic nervous system via oxidative stress through angiotensin II type 1 receptor in the RVLM, and the changes are greater compared to those in WKY, and are maintained for the period of 'jet lag'. These results suggest that experimental 'jet lag' causes sympathoexcitation via oxidative stress through AT(1) receptor in the brain, especially in hypertension.

An autopsy case of disseminated strongyloidiasis combined with cytomegalovirus infection

We report a rare autopsy case of disseminated strongyloidiasis combined with cytomegalovirus co-infection involving a 68-year-old man, who was originally from Okinawa Prefecture in southern Japan, where strongyloidiasis occurs sporadically among the elderly. This patient was admitted with a diagnosis of drug eruption and hypereosinophilic syndrome. He was administered steroid therapy, but suffered complications of fever, respiratory distress, and pulmonary hemorrhaging. The autopsy findings showed disseminated strongyloidiasis in the alveolar spaces and the intestine and cytomegalovirus inclusion body foci in the lungs.

Ubiquitin-positive pneumocytes and inclusion bodies are present in secondary organizing pneumonia

OBJECTIVE

We previously reported that various types of interstitial pneumonia (IP) patterns contain intracytoplasmic eosinophilic inclusions or Mallory bodies (inclusions) that are ubiquitin positive (Ub+). In the present study, we examined tissues with the organizing pneumonia pattern (OP) to determine if they contain inclusions and Ub+ pneumocytes using lobectomized specimens.

METHODS

Tissues from 34 patients with secondary OP, which appeared in 33 carcinomas and 1 pulmonary abscess, were histologically evaluated for the type of intraluminal granulation tissue and the presence of erosions and inclusions. Granulation tissues were classified into polypoid, mural and occluded subtypes according to Basset's criteria and scored.

RESULTS

Inclusions were noted in 5.9% of the secondary OP cases with light microscope. Ub+ pneumocytes were detected after immunostaining and all inclusions were Ub+. Ub+ pneumocytes (inclusions) were noted in 14.7% of the secondary OP cases. OP contained pneumocyte erosions and inflammatory cell infiltration without a significant difference in the Ub+ and Ub- subgroups. Although there was no significant difference in the polypoid type of granulation tissue between the Ub+ and Ub- negative (Ub-) subgroups, the Ub+ subgroup had significant increases (p<0.05) in the mural-occluded type of granulation tissue (Ub+: 1.76±0.64, n=5 vs. Ub-: 0.72±0.87, n=29) as compared to the Ub- subgroup.

CONCLUSION

Some patients with secondary OP had Ub+ inclusions as pneumocyte injury.

[Autopsy case of corticosteroid-induced invasive pulmonary aspergillosis with cavity-formation]

Invasive pulmonary aspergillosis (IPA) is an important and fatal complication in the patients with neutropenic or immunosuppressed condition. In spite of intensive treatment with anti-fungal drugs, the prognosis of the patients who have been suffered from IPA is extremely poor. This case was an 85-year-old Japanese man who was diagnosed as idiopathic thrombocytopenic purpura (ITP). He underwent high-dose corticosteroids and gamma-globulin therapy. During the hospitalization, he complained respiratory symptoms, and the abnormal shadow suggesting pulmonary infiltration and cavitation was pointed out on chest imaging. He was diagnosed as IPA because of high level of serum beta-D-glucan and positive for aspergillus antigen. Although he underwent intensive care with anti-fungal drug administration and artificial respiration, he died of respiratory distress on the 68th hospitalization. Postmortem examination disclosed severe bronchopneumonia, cavitation and pulmonary arterial thrombi in both lungs. Histological examination showed widely distributed epitheloid cell granulomata with central necrosis containing aspergillus hyphae, and vasodestructive growth of fungus with occasional organized thrombi.

Extraskeletal myxoid chondrosarcoma: a study using a quick-freezing and deep-etching method

A case of extraskeletal myxoid chondrosarcoma (ESMC), which developed in the right thigh of a middle-aged Japanese woman, was studied using immunohistochemistry, conventional electron microscopy, and the quick-freezing and deep-etching (QF-DE) method. In addition to typical light microscopic findings of ESMC, conventional electron microscopy indicated that the tumor cells had features of chondrocytes. Immunohistochemically, the tumor cells showed a positive immunoreaction for S100 protein. A diagnosis of ESMC was made. An interesting observation was the ultrastructural features of collagen fibrils in the myxoid matrix highlighted by the QF-DE method. These collagen fibrils consisted of relatively thin collagen (20-35 nm) with pleated surface structures. The surface striation at 65 nm was obscure. We consider that such a finding of collagen fibrils identified by the QF-DE method is one of the characteristics of the myxoid matrix of ESMC, and this is useful for the differential diagnosis of myxoid soft tissue tumors.

Poly I:C-induced expression of intercellular adhesion molecule-1 in intestinal epithelial cells

Intercellular adhesion molecul-1 (ICAM-1) is a transmembrane glycoprotein belonging to the immunoglobulin superfamily of adhesion molecules and plays perdominant roles in recruitment and trafficking of leucocytes to sites of inflammation. ICAM-1 expression in intestinal epithelial cells (IECs) is enhanced by several stimuli, such as proinflammatory cytokines, bacterial infections or pathogen-associated molecular patterns. One of these stimuli, double-stranded RNA (dsRNA), is a by-product of viral replication and can be recognized by its cognate receptor Toll-like receptor 3 (TLR-3). In spite of expression of both TLR-3 and ICAM-1 in IECs, correlation between TLR-3-signalling and ICAM-1 expression has never been examined in IECs. In the present study, we investigated whether poly I:C, an analogue of dsRNA, can stimulate the expression of ICAM-1 in IEC line, HT-29. Poly I:C-stimulation up-regulated the expression of ICAM-1 mRNA by real-time polymerase chain reaction. Enhanced expression of ICAM-1 was confirmed in protein level by immunofluoresense cell staining and enzyme-linked immunosorbent assay by measuring the released soluble ICAM-1 in culture supernatant. As the stimulation effect was reduced by pre-treatment of the cells with anti-TLR-3 antibody, poly I:C-binding signal was thought to be sensed by TLR-3 on the surface of HT-29. The results of luciferase assay and nuclear factor kappa-b (NF-kappaB) inhibitor treatment experiments indicated that the downstream signal was mainly transduced by transcription factor, NF-kappaB. All these results demonstrated the connection between TLR-3 signalling and ICAM-1 expression in HT-29 cells and indicated the importance of coordinated function of both innate and adaptive immunity against viral infections.

Ruptured giant aneurysm of the left anterior descending coronary artery in Kawasaki disease

This report describes Kawasaki disease (KD) in a rare autopsy case showing three uncommon phenomena: rapid aneurysmal development, ruptured giant aneurysm, and abscesses such as neutrophil aggregations, all contributing to the unpreventable sudden death of patients with KD. For a 5-year-old boy, KD was diagnosed on day 5 of his illness. His aneurysm was enlarged to a diameter of 18 mm on day 12, and the boy died on day 13. Aggregations of neutrophils containing myeloperoxidase and neutrophil elastase were scattered in chains over the aneurysmal wall of coronary artery, suggesting that destruction of the wall by an enzyme may have caused the rupture of the aneurysm.

An intravenous replenishment of salivary components decrease water intake and increases feed intake in freely drinking large-type goats fed on dry forage

This research utilized two treatments to investigate if feed intake is reduced by changes in humoral factors induced by dry forage feeding in large-type goats given free access to water. In the control treatment (NI), a solution was not infused. The artificial parotid saliva i.v. infusion (ASI) treatment consisted of an i.v. infusion of artificial parotid saliva in order to replenish NaHCO3 and fluids lost from the blood to the rumen due to increased saliva secretion volume during initial stages of dry forage feeding. The ASI treatment significantly mitigated the decreases in circulating plasma volume caused by saliva secretion. Thirst was lower in the ASI-treated group, as indicated by the lower water intake (NI, 3894 mL 2 h-1; ASI, 3100 mL 2 h-1). Decreases with time in dry forage intake were significantly reduced by the ASI treatment (2134g 2 h-1) compared with the NI control (1756 g 2 h-1). These results indicate that under free drinking conditions, dry forage intake of large-type goats may likely be suppressed by the decrease in plasma volume and increase in water intake following saliva secretion during the initial stages of feeding. Key words: Dry forage intake, water intake, large-type goat

Characterization of ouabain-induced noradrenaline and acetylcholine release from in situ cardiac autonomic nerve endings

AIM

Although ouabain modulates autonomic nerve ending function, it is uncertain whether ouabain-induced releasing mechanism differs between in vivo sympathetic and parasympathetic nerve endings. Using cardiac dialysis, we examined how ouabain induces neurotransmitter release from autonomic nerve ending.

METHODS

Dialysis probe was implanted in left ventricle, and dialysate noradrenaline (NA) or acetylcholine (ACh) levels in the anaesthetized cats were measured as indices of neurotransmitter release from post-ganglionic autonomic nerve endings.

RESULTS

Locally applied ouabain (100 microm) increased in dialysate NA or ACh levels. The ouabain-induced increases in NA levels remained unaffected by cardiac sympathetic denervation and tetrodotoxin (Na+ channel blocker, TTX), but the ouabain-induced increases in ACh levels were attenuated by TTX. The ouabain-induced increases in NA levels were suppressed by pretreatment with desipramine (NA transport blocker) and augmented by reserpine (vesicle NA transport blocker). In contrast, the ouabain-induced increases in ACh levels remained unaffected by pretreatment with hemicholinium-3 (choline transport blocker) but suppressed by vesamicol (vesicle ACh transport blocker). The ouabain-induced increases in NA levels were suppressed by pretreatment with omega-conotoxin GVIA (N-type Ca2+ channel blocker), verapamil (L-type Ca2+ channel blocker) and TMB-8 (intracellular Ca2+ antagonist). The ouabain-induced increases in ACh levels were suppressed by pretreatment with omega-conotoxin MVIIC (P/Q-type Ca2+ channel blocker), and TMB-8.

CONCLUSIONS

Ouabain-induced NA release is attributable to the mechanisms of regional exocytosis and/or carrier-mediated outward transport of NA, from stored NA vesicle and/or axoplasma, respectively, while the ouabain-induced ACh release is attributable to the mechanism of exocytosis, which is triggered by regional depolarization. At both sympathetic and parasympathetic nerve endings, the regional exocytosis is because of opening of calcium channels and intracellular calcium mobilization.

A sieve electrode as a potential autonomic neural interface for bionic medicine

We examined the applicability of a sieve electrode to the autonomic nervous system as a potential neural interface for bionic medicine. We developed, using a Si-semiconductor process, a sieve electrode having a square diaphragm (1 mm in one side, 12 microm in thickness) with 30-81 penetrating square holes (50-100 microm in one side). In the first protocol, we implanted the sieve electrode to the vagal nerve in rats. One hundred and twenty days after the implantation, cuff electrodes were attached to the vagal nerve proximal and distal to the sieve electrode under halothane anesthesia. The evoked action potential was recorded from the sieve electrode by nerve stimulation via the cuff electrodes. The evoked action potential was also recorded from the cuff electrodes by nerve stimulation via the sieve electrode. In the second protocol, we implanted the sieve electrode to the renal sympathetic nerve in rabbits. Forty days after the implantation, the spontaneous action potential or sympathetic nerve activity was recorded under pentobarbital anesthesia. In conclusion, we were able to record the evoked and spontaneous action potentials using the sieve electrode. The sieve electrode will provide a useful neural interface for recording and stimulating the autonomic nervous system.

Supplemental utility of nested PCR for the pathological diagnosis of disseminated trichosporonosis

Disseminated trichosporonosis is known to be a severe opportunistic mycosis and has a high mortality rate. In autopsy cases, it is often difficult to diagnose as trichosporonosis because the causative Trichosporon species are pathologically similar to other fungi, especially the Candida species. Immunohistochemical analysis is essential for the differential diagnosis, but an antibody to Trichosporon is not available commercially. In the present study, we investigated the supplemental utility of nested polymerase chain reaction (PCR) for the pathological diagnosis of trichosporonosis from formalin-fixed and paraffin-embedded tissues. Total DNA was purified from 30 major organs in three autopsy cases, and Trichosporon DNA was specifically amplified by nested PCR using three sets of primers. Of 22 organs in which Grocott's stain was positive for fungal infection, 170- and 259-bp PCR products were detected in 20 (91%) and 12 (55%) organs, respectively. In short-term fixation (about 1 day), these bands were highly detected in ten (100%) and nine (90%) organs, whereas the detection efficiency tended to decrease after long-term fixation and decalcification. No PCR product of 412 bp was detected in any organs. These findings suggest that nested PCR from short-term-fixed tissues is useful for supportive pathological diagnosis of disseminated trichosporonosis.

Insignificant effects of plasma catecholamines on dynamic heart rate regulation by the cardiac sympathetic nerve

Although plasma catecholamines such as norepinephrine (NE) and epinephrine (Epi) increase during severe exercise, the effects of high levels of plasma catecholamines on dynamic heart rate (HR) regulation by the cardiac sympathetic nerve remains unknown. The aim of the present study was to examine the effects of plasma catecholamines on the transfer function from sympathetic nerve stimulation to HR. In anesthetized rabbits, we randomly stimulated the right cardiac sympathetic nerve according to a binary white noise signal while measuring HR. The effects of intravenous NE administration at 1 and 10 mugmiddotkg^-1middoth^-1 were examined in 6 rabbits. The effects of intravenous Epi administration at 1 and 10 mugmiddotkg^-1middoth^-1 were examined in different 6 rabbits. Although plasma NE increased 10 times as high as the baseline level during the NE administration at mugmiddotkg^-1middoth^-1 , dynamic gain of the transfer function was not changed significantly (7.1plusmn1.2, 6.9plusmn1.1, and 7.7plusmn1.1 beatsmiddotmin^-1middotHz^-1). Similarly, although plasma Epi increased 10 times as high as the baseline level during the Epi administration at 10 mugmiddotkg^-1middoth^-1, dynamic gain of the transfer function was not changed significantly (7.5plusmn0.8, 7.9plusmn0.8, and 7.6plusmn1.2 beatsmiddotmin^-1middotHz^-1). In conclusion, plasma catecholamines of physiologically-relevant high concentrations did not interfere with the dynamic HR regulation by the cardiac sympathetic nerve.

Transfer function analysis of carotid sinus baroreceptor transduction

The carotid sinus baroreflex is one of the most important negative feedback systems that regulate arterial pressure. The neural arc transfer function from carotid sinus pressure (CSP) input to efferent sympathetic nerve activity shows a gain increase of approximately 10 dB when input frequency increases from 0.01 to 0.5 Hz. The transfer gain of the neural arc decreases in the frequency range above 0.8 Hz. The aim of the present study was to elucidate the extent of contribution of the carotid sinus baroreceptor transduction to the determination of the neural arc dynamic characteristics. In 7 anesthetized rabbits, we isolated the right carotid sinus and controlled CSP while recording afferent nerve activity (ANA) from the carotid sinus nerve. CSP was randomly assigned to either 80 or 120 mmHg with a switching interval of 50 ms according to a binary white noise signal for 15 min. The transfer function from CSP to ANA was estimated in the frequency range from 0.01 to 3 Hz. The transfer function showed a gain increase of approximately 4.6 dB when input frequency increased from 0.01 to 0.3 Hz. The transfer gain remained relatively constant up to 3 Hz. These results suggest that the carotid sinus baroreceptor transduction partly contributes to the gain increase of the baroreflex neural arc in the frequency range from 0.01 to 0.5 Hz but not the gain decrease above 0.8 Hz.