Brainstem mechanisms of autonomic dysfunction in encephalopathy-associated Shiga toxin 2 intoxication

Acute encephalopathy is the major determinant of death in an early stage of Shiga toxin (Stx)-producing Escherichia coli infection. Rapid progress toward refractory hypotension and dysfunction of breathing implies autonomic center dysfunction of patients. To clarify whether autonomic dysfunction becomes an ultimate cause of death in Shiga toxemia, we injected purified Stx2 (20 microg/kg) intravenously into rabbits, and monitored changes in cardiovascular and respiratory function together with renal sympathetic nerve activity (RSNA) in the conscious state. After an approximately 24-hour silent (lag) period, all rabbits given Stx2 developed hemorrhagic diarrhea (25.7 +/- 1.1 hours) and limb paralysis (31.2 +/- 1.3 hours). This limb paralysis was observed initially in the hind legs, and then it gradually extended to the forelegs. After 23.2 +/- 2.3 hours, RSNA increased gradually, and arterial blood pressure was maintained within normal limits together with an increase in the maximum gain of baroreflex response. Severe hypotension developed within 34.8 +/- 2.2 hours, without any increase in heart rate; RSNA significantly increased by 39.5 +/- 0.9 hours. In the final stage, RSNA decreased concurrently with decreases in arterial blood pressure, heart rate, and baroreflex response, suggesting dysfunction of the baroreflex control system. Thereafter, all rabbits died within 47.8 +/- 1.2 hours after the intravenous Stx2 injection. Magnetic resonance imagings of the central nervous system (T2-weighted images) showed high-intensity areas in the dorsal two-thirds of the cervical spinal cord and brainstem 48 hours after Stx2 administration. These results show that the cause of death is circulatory failure caused by impairment of the cardiovascular center in the medulla. We believe that this animal model helps to clarify the mechanism of rapid progress to death of patients with Shiga toxin-producing E. coli infection.

[Implantation of the artificial retina]

In some degenerative retinal diseases, e.g., retinitis pigmentosa and age-related macular degeneration, the photoreceptors are destroyed to cause serious visual defects. Recent studies on blind human subjects revealed that a large number of ganglion cells remains intact and is capable of transmitting signals to the brain to evoke partial visual perception. This provided hope to compensate for the visual defects with retinal prostheses. The recent progress of microfabrication technique made it possible to implement the Vary Large Scale Integrated circuit, the artificial retina, which emulates a part of retinal function. The idea of implanting the artificial retina to the patients was proposed recently and experiments using animals have been put into practice. This article surveys the front line of the artificial retina implantation.

[The problems of nursing and medical expenses in end-stage home therapy]

Recently, many end-stage patients and their families desire home care in their last days, because Japanese tend to think "quality of life" is the most important thing in their life. Home therapy for end-stage patients has become popular with the support of the government. The cooperation between medical staff and patients has overcome many problems derived from this new therapy system. Problems related to the person who looks after the patient, however, remain to be solved. Ninety-four home therapy cases of end-stage cancer have been treated as a private clinic experience since 1994. Although the medical expenses for home therapy are greater than for hospital treatment under the Japanese medical insurance system, the nursing fees for the person who looks after the patient are not considered enough. A heavy burden, not only by the nursing but also by their own occupation, has been imposed upon the nursing person. Differences in the expenses between home therapy and hospital treatment, and also the situation of the nursing person in the home therapy are reported in this paper.

Hypoxic adaptation of the peptidergic innervation in the rat carotid body

The abundance of substance P (SP)-, calcitonin gene-related peptide (CGRP)-, vasoactive intestinal polypeptide (VIP)-, and neuropeptide Y (NPY)-immunoreactive nerve fibers in the carotid body was compared between normoxic and chronically hypoxic rats (10% O2 and 3.0-4.0% CO2 for 3 months). The immunoreactive fibers appeared as thin processes with many varicosities, and were distributed mainly around the vasculatures. In the normoxic control carotid body, NPY fibers were more numerous than VIP, CGRP, and SP fibers. In the chronically hypoxic rats, the carotid body was enlarged several fold, and the mean absolute number of VIP and NPY fibers was 3.88 and 2.22 times higher than in the normoxic carotid body, respectively, although that of SP and CGRP fibers was not changed. When expressed as density per unit area of the parenchyma, the density of SP and CGRP fibers in the chronically hypoxic carotid body decreased significantly to under 50%, the density of VIP fibers increased significantly 1.80 times, and the density of NPY fibers were unchanged. Immunoreactivity for four neuropeptides was not found in the glomus cells of normoxic or chronically hypoxic carotid bodies. These results suggest that altered peptidergic innervation of the chronically hypoxic carotid body is one feature of hypoxic adaptation. Because these neuropeptides are vasoactive in nature, altered carotid body circulation may contribute to modulation of the chemosensory mechanisms by chronic hypoxia.

Suppression of hyperemia after brain ischemia by L-threo-3,4-dihydroxyphenylserine

Although several studies have shown that L-threo3,4-dihydroxyphenylserine (DOPS) may provide a neuroprotective effect against ischemic brain damage, its protective mechanism is not fully understood. Glutamate release and hippocampal blood flow in ischemia with administration of DOPS were investigated to elucidate the neuroprotective mechanism of DOPS. Pre- (but not post-) ischemic administration of DOPS rescued 73% of hippocampal CA1 neurons (p < 0.001, compared with ischemia only) 1 week after transient global ischemia in gerbils. While glutamate release induced by ischemia was not affected, the increase of hippocampal blood flow during reperfusion was significantly suppressed by DOPS. These results demonstrate that DOPS may prevent reperfusion injury by suppression of hyperemia after ischemia, resulting in neuroprotection.

Different effects of prolonged isocapnic hypoxia on the carotid body and the glomus cells in the wall of the common carotid artery of the chicken

In the chicken, glomus cells are widely distributed not only in the carotid body but also in the wall of the common carotid artery and around each artery arising from the common carotid artery. Effects of chronic isocapnic hypoxia on the chicken carotid body and the glomus cells in and around the arteries were examined by immunohistochemistry and electron microscopy. In chickens exposed to isocapnic hypoxia for 35 days, three- to four-fold increase of the carotid body volume was induced. Immunoreactivity for tyrosine hydroxylase of glomus cells almost completely disappeared. Dense networks of TuJ1-immunoreactive nerve fibers were unchanged, whereas peptidergic nerve fibers, i.e., substance P-, calcitonin gene-related peptide-, vasoactive intestinal peptide-, galanin- and neuropeptide Y-immunoreactive fibers, were decreased in and around the carotid body. At the electron microscopic level, increased secretory activity of the glomus cells was verified. Mature dense-cored vesicles were markedly decreased, although prosecretory granules were numerous around Golgi complexes. Many immature glomus cells filled with rough endoplasmic reticulum and free ribosomes, also appeared in the carotid bodies of hypoxic chickens. In contrast to the carotid body, the glomus cells located in the wall of the common carotid artery revealed no changes after long-term hypoxia. The cells in the hypoxic chickens, as well as normal controls, expressed intense immunoreactivity for neuropeptide Y, serotonin and chromogranin A. Furthermore, a large number of dense-cored vesicles were distributed throughout the cytoplasm. The glomus cells around each artery arising from the common carotid artery were affected by hypoxia, although the degree of their response to hypoxia varied depending on the locations.

Effects of systemic hypoxia on R-R interval and blood pressure variabilities in conscious rats

The effects of systemic hypoxia with different levels of CO2 on R-R interval (RRI) and systolic blood pressure (SBP) variabilities were investigated in conscious rats. Wistar rats chronically instrumented for the measurement of blood pressure, electrocardiogram, and renal sympathetic nerve activity (RSNA) were exposed to hypocapnic (Hypo), isocapnic (Iso), and hypercapnic (Hyper) hypoxia. On another day, the rats were treated with atropine and exposed to the same type of hypoxia. Sinoaortic denervation (SAD)-treated rats were exposed to Iso and Hyper, and RRI and SBP variabilities before and during hypoxia were analyzed using the maximum-entropy method with high resolution. With regard to RRI variability, very low frequency (VLF), low frequency (LF), and high frequency (HF) powers all decreased during Hypo, increased during Hyper, and did not change during Iso in intact rats. Changes during Hypo were attenuated by atropine, and those during Hyper were abolished by either atropine or SAD. The ratio of LF power to HF power decreased independently of increases in RSNA during each type of hypoxia. On the other hand, there were no changes in VLF, LF, or HF power in SBP variability during each type of hypoxia in intact rats. In atropine-treated rats, LF power increased during Iso and Hyper and HF power increased during each type of hypoxia. There was no difference in respiratory frequency among the three kinds of hypoxia in both intact and atropine-treated rats. The results suggest that arterial PCO2 level rather than respiration frequency produces changes in powers of RRI variability through changes in parasympathetic nerve activity and that with regard to SBP variability, parasympathetic nerve activity masks changes in LF power that reflect an increase in RSNA and those in HF power that reflect a mechanical consequence of respiration.

Ca2+ regulation by the Na(+)-Ca2+ exchanger in retinal horizontal cells depolarized by L-glutamate

This study is concerned with regulation of the intracellular Ca2+ concentration ([Ca2+]i) of horizontal cells isolated from cyprinid fish retinae, with the main emphasis on the role of the (Na+)-Ca2+ exchanger. An inward current was blocked by Ca2+ (4 mM) during prolonged (> 1 h) depolarization by L-glutamate (100 microM) in the whole-cell voltage-clamp configuration, suggesting the persistent activation of voltage-gated Ca2+ channels. This (Co2+)-sensitive current was absent when extracellular Na+ was replaced by Li+ to suppress (Na+)-Ca2+ exchange. Measurement of [Ca2+]i using the Fura-2 ratiometric method gave the following results. (1) L-Glutamate (100 microM) caused [Ca2+]i to increase from the resting level of 75.4+/-36.8 nM (mean +/-S.D., n = 11) to the maximum level (2.2+/-1.4 microM, n = 11) within 15 s and then to decrease to a steady level of 0.59+/-0.23 microM (n = 11). (2) Nifedipine (100 microM) lowered the L-glutamate-induced steady [Ca2+]i level, which was still higher than the resting level. (3) L-Glutamate caused [Ca2+]i to increase even after blockading the voltage-gated Ca2+ channels by nifedipine or by clamping the membrane voltage at -55 mV. (4) (Na+)-free superfusate elevated the L-glutamate-induced steady [Ca2+]i level. (5) The time course of the [Ca2+]i decrease from the L-glutamate-induced steady level to the resting level was prolonged in the (Na+)-free superfusate. These results suggest that the (Na+)-Ca2+ exchanger extrudes intracellular Ca2+ to maintain a low [Ca2+]i level by counteracting the continuous Ca2+ influx through the voltage-gated Ca2+ channels and glutamate-gated channels when horizontal cells in situ are tonically depolarized by L-glutamate released from the photoreceptors. The (Na+)-Ca2+ exchange current isolated by a voltage-clamp experiment depends exponentially on the membrane potential.

[An operative case of spontaneous rupture of the esophagus 10 days after the onset]

This paper presents a rare case of spontaneous rupture of the esophagus operated on 10 days subsequent to its onset. A 69-year-old male, who was diagnosed as acute pancreatitis, came to this department after 10 days of conservative therapy. Emergency examination including computed tomography, esophagoscopy and esophagography indicated spontaneous rupture of the esophagus. At operation, despite severe inflammation of the pleural cavity, a 2 cm horizontal tear at the left wall of the lower esophagus could be directly closed, and reinforced with fibrin glue. Postoperative decompression therapy prevented the rupture of the closure. The early symptoms resemble other emergency diseases, thus making correct diagnosis difficult. Early management is required for lifesaving, and preoperative aggressive exploration must thus be conducted. Postoperative management including through decompression of the gastrointestinal tract is also essential, regardless of the mode of operation.

Molecular basis of intermittent maple syrup urine disease: novel mutations in the E2 gene of the branched-chain alpha-keto acid dehydrogenase complex

The E2 gene of the branched-chain alpha-keto acid dehydrogenase (BCKDH) complex was studied at the molecular level in three patients with intermittent maple syrup urine disease (MSUD). All three patients had higher BCKDH activity than did those with the classical phenotype. In the first patient, a single base substitution from A to G in intron 8 created a new 5' splice site and caused an insertion of 126 nucleotides between exons 8 and 9 by activating an upstream cryptic 3' splice site in the same intron. The predicted mRNA encoded a truncated protein with 282 amino acids including 4 novel ones at the carboxyl terminus, compared with the normal protein with 421 amino acids. In vitro, the region from the patient but not from a normal control was recognized and was recovered as a novel exon, indicating that the single substitution was responsible for incorporation of the region into mRNA. This mutation probably supports an exon definition model in which the spliceosome recognizes a 3' splice site and then scans downstream for an acceptable 5' splice site, thereby defining an exon. The second patient was homozygous for a G to T transversion at nucleotide 1463 in exon 11, which predicted a substitution of the termination codon by a leucine residue and the addition of 7 extra amino acids at the carboxyl terminus. For each mutation, these two patients were homozygous and their parents were heterozygous. The third patient was a compound heterozygote for a C to G transversion at nucleotide 309 in exon 4 and a G to A transition at nucleotide 1165 in exon 9, causing an Ile-to-Met substitution at amino acid 37 and a Gly-to-Ser substitution at amino acid 323, respectively. Taken together, these results indicate that the molecular basis of intermittent phenotype MSUD in some patients can be due to mutations in the E2 gene, giving rise to a low but significant residual activity of the BCKDH complex.

Changes in the distribution of nitric oxide synthase immunoreactive nerve fibers in the chronically hypoxic rat carotid body

The distribution of nitric oxide synthase (NOS) immunoreactive nerve fibers in the carotid body was compared between normoxic and chronically hypoxic rats (10% O2 and 3.0-4.0% CO2 for 3 months). NOS immunoreactive fibers appeared as thin processes with many varicosities. They were distributed predominantly around small arteries and arterioles, and around clusters of glomus cells. When expressed by the density of varicosities per unit area in the parenchyma, the density of NOS fibers associated with the vasculature and with the glomus cells in the chronically hypoxic carotid bodies was significantly decreased. Because nitric oxide (NO) is an inhibitory neuronal messenger in the normoxic carotid body, the present findings suggest that the sensory mechanisms in the hypoxic carotid body may be involved in 'disinhibition' resulting from reduced NO synthesis.

Thyroid hormones are involved in insulin-like growth factor-I (IGF-I) production by stimulating hepatic growth hormone receptor (GHR) gene expression in the chicken

Effect of thyroid status on IGF-I production in growing chickens was studied. Serum concentrations of GH were not affected by propylthiouracil (PTU) or thyroxine (T4) treatments, whereas serum IGF-I levels were significantly decreased in PTU-treated chickens. The lowered serum IGF-I levels in the PTU-treated group were completely restored to the control levels by T4 injections. In the liver, the messenger RNA (mRNA) expressions both for GH receptor (GHR) and IGF-I were significantly repressed by PTU treatment, and were restored again by T4 replacement. In addition, the results of analysis on radiolabelled GH binding to the liver membrane were consistent with the levels of hepatic GHR mRNA expression. Serum concentrations of IGF-I were positively correlated with hepatic IGF-I mRNA and GHR mRNA expressions. The correlation coefficient between serum T3 levels and hepatic IGF-I mRNA expressions was also significant. These results indicate that thyroid hormones regulate IGF-I production in the chicken by affecting hepatic GHR expression.

Substance P- and calcitonin gene-related peptide-containing nerve fibers in the nasal mucosa of chronically hypoxic rats

The distribution of substance P-immunoreactive and calcitonin gene-related peptide-immunoreactive nerve fibers in the nasal mucosa was compared between normoxic and chronically hypoxic rats (10% O2 and 3.0-4.0% CO2 for 3 months). In the normoxic nasal mucosa, substance P- and calcitonin gene-related peptide-immunoreactive nerve fibers were found within and under the epithelium and around the glands and blood vessels in the lamina propria. These immunoreactive fibers have many varicosities. In the chronically hypoxic nasal mucosa, the relative density of intra- and subepithelial substance P-immunoreactive and calcitonin gene-related peptide-immunoreactive fibers and those in the lamina propria was higher than in normoxic mucosa. The length of substance P-positive fibers within the chronically hypoxic olfactory and respiratory epithelium was 1.66 and 2.45 times higher than within the normoxic epithelium, respectively. The length of calcitonin gene-related peptide-immunostained fibers within the chronically hypoxic olfactory and respiratory epithelium was 1.56 and 1.84 times higher, respectively. Because substance P and calcitonin gene-related peptide are the predominant signal peptides of primary sensory neurons, the increased number of these fibers may represent enhanced sensory mechanisms in the hypoxic nasal mucosa. In addition, considered together with the findings in chronically hypoxic tracheal mucosa, the increased density of intraepithelial fibers containing substance P and calcitonin gene-related peptide suggests that this is a predominant feature of hypoxic adaptation throughout the upper and lower respiratory tracts.

Evaluation of abdominal lymphadenopathy in children by ultrasonography

BACKGROUND

There may be uncertainty as to whether enlarged abdominal lymph nodes (LNs) in children are normal or abnormal.

OBJECTIVE

To compare, by ultrasonography (US), enlarged abdominal LNs in healthy children with those in children with acute abdominal pain or acute gastroenteritis.

MATERIALS AND METHODS

One hundred and twenty-two asymptomatic children were selected by questionnaire and compared with 44 children with acute abdominal pain of unknown origin and 27 children with acute gastroenteritis. The number of LNs, their location, their shape and the presence of tenderness as detected by finger compression of each LN were evaluated. The children were divided into four groups according to age: 0-2, 3-6, 7-10, and 11-15 years.

RESULTS

LNs were detected in the ileo-caecal and/or para-aortic areas in almost all of the asymptomatic children. The number of large LNs ( > 10 mm) in the para-aortic areas was higher in the older children (>/= 7 years of age) than in the younger children ( </= 6 years of age) (P < 0.05). The number of spindle-shaped LNs (ratio of long- to short-axis diameter >/= 2.0) was increased in the older children. The number of LNs was not increased in the children with acute abdominal pain. The size of the LNs was largest in the children with acute gastroenteritis, followed by the children with acute abdominal pain and the asymptomatic children (P < 0.001). Although the shape of the LNs was no different among the three groups of children, the frequency of round-shaped LNs (ratio of long- to short-axis diameter < 2.0) was greater in the older children with acute abdominal pain or acute gastroenteritis than in the asymptomatic children (P < 0.01). The number of LNs with tenderness detected by finger compression was significantly greater in the children with acute abdominal pain and acute gastroenteritis than in the asymptomatic children (P < 0.0001).

CONCLUSION

The number of large and round-shaped LNs with tenderness tended to be increased in the children with acute gastroenteritis and acute abdominal pain. There is no clear specificity of LN enlargement in the children with acute abdominal pain, and the main challenge is to diagnose or estimate the organic pathology by US, regardless of the presence of lymphadenopathy.

Single-trial analysis of P3 in patients with generalized epilepsy

The latencies and amplitudes of averaged P3, and the latencies, amplitudes and frequency components of single EEG responses to target tones were analyzed in 9 control subjects (CS group), 6 epileptics whose mean IQ was 100 (EP group) and 6 epileptics whose mean IQ was 52 (RE group), using an auditory oddball task. All of the subjects responded to the target tones correctly and there were no differences in the incidence of error in response to the target tones, or in the latencies and amplitudes of the averaged P3 among the three groups. However, the reaction times (RTs) in the RE group were significantly longer than those in the other groups (P < 0.05). Single EEG responses to target tone (single-trial ERPs) were classified into 2 types, those with and those without the P3 component. Type 1 had the P3 component and was observed in 42% of all of the responses in the RE group, significantly less than those in the CS (64%) and EP (61%) groups. The peak latencies of P3 in type 1 were similar among the three groups, but the amplitudes of P3 in type 1 in the RE group were significantly greater than those in the CS and EP groups. RTs in the RE group were significantly longer than those in the other groups, and had no correlation with the P3 latencies of type 1. There was little difference in the results of the frequency analysis among the three groups. These results suggest that all subjects in three groups recognized the target tones correctly, but they did not evaluate every target tone, since the incidence of P3 was almost 60% in the CS and EP groups, and 40% in the RE group. The characteristics of cognition and evaluation in three groups were the same, but the decrease in incidence of evaluation and the dissociation between the cognition and the response execution might be caused by impairment of the subject-environment contact mechanism, which resulted in the decrement of IQ in the RE group.

Diffuse fibromatosis on the scalp in infancy: a variant of juvenile hyaline fibromatosis

Various types of fibromatosis have been reported in infancy and early childhood. We describe an infant with diffuse fibromatosis on the scalp. A one year and five months-old girl showed a diffuse and hard mass 3 x 5 cm in diameter and no tenderness on the scalp. Two months later, the size of the mass had increased and several other tumors appeared on the lateral head. The magnetic resonance imaging (MRI) disclosed that a large and diffuse tumor had spread from the frontal to occipital head; a 'helmet-like' configuration of the tumor was exhibited on sagittal MR images. The tumor showed high signal intensity on T2-weighted images and was enhanced with Gd-DTPA. Histological examination showed a fibroblastic proliferation with intervening thick collagen bundles. The patient was diagnosed as having diffuse fibromatosis. The tumor at the resection site immediately recurred, whereas the tumor in the frontal head showed marked regression. Three months after the resection, new tumors appeared in the occipital head. The size and number of these tumors have remained unchanged for more than 18 months. The sites and appearance of the tumors were identical to that of juvenile hyaline fibromatosis (JHF) in this patient. However, JHF usually includes fibroblasts associated with large amounts of hyalinized collagen-like material, which were not present in our patient. The different histology of JHF comparing our case and other reported cases may depend on the different phase of the disease progression at resection. Long-term observation is necessary for the appropriate diagnosis and evaluation of prognosis in this patient.

Effect of carbon dioxide on autonomic cardiovascular responses to systemic hypoxia in conscious rats

The contribution of the autonomic nervous system to the cardiovascular response to hypoxia with different levels of CO2 was investigated in conscious rats. Wistar rats were chronically instrumented for measurement of arterial blood pressure (ABP), electrocardiogram, and renal sympathetic nerve activity (RSNA). They were exposed to 1) hypocapnic hypoxia (Hypo), 2) isocapnic hypoxia (Iso), and 3) hypercapnic hypoxia (Hyper). Hypo caused a decrease in ABP, an increase in heart rate (HR) and RSNA, and a slight increase in plasma norepinephrine (NE). Iso caused no significant change in ABP or HR but did cause an increase in RSNA and plasma NE. Hyper caused an increase in ABP, a decrease in HR, and an increase in RSNA and plasma NE. In sinoaortic-denervated (SAD) rats, ABP and RSNA decreased and HR tended to decrease during Iso. SAD abolished the bradycardic response during Hyper. Atropine abolished the bradycardic response during Hyper, and HR tended to increase during all three kinds of hypoxia. In all three kinds of hypoxia, ABP and renal sympathetic nervous responses in atropine-treated rats were not significantly different from those in intact rats. These results indicate that Hypo causes sympathetic activation and parasympathetic inhibition while Iso and Hyper cause sympathetic and parasympathetic activation via peripheral chemoreceptors. The MABP-RSNA curve tended to shift to the left and the maximum gain of the baroreflex response tended to decrease during Hypo. In contrast, this curve shifted to the right and the maximum gain of the baroreflex response increased during Iso and Hyper, suggesting that baroreflex function is affected by arterial CO2 levels. We concluded that cardiovascular responses during hypoxia are modified by arterial Pco2 levels and mediated by the autonomic nervous system.

Rhabdomyosarcoma of the urachus. A case report

BACKGROUND

Rhabdomyosarcoma of the urachus is extremely rare, and only two cases have been reported. Cytologic, histologic, immunochemical and electron microscopic findings in embryonal rhabdomyosarcoma of the urachus are presented.

CASE

Embryonal rhabdomyosarcoma of the urachus developed in a 2-year-old boy. Imprint smears prepared prior to a histologic examination for a rapid report contained many malignant cells isolated or in clusters in a myxoid background. They were uniformly small, with round to oval nuclei and scant cytoplasm, and immunohistochemically positive for desmin and alpha-sarcomeric muscle actin but negative for myoglobin. This tumor was diagnosed cytologically as embryonal rhabdomyosarcoma because of its skeletal muscle origin and because of its similarity to one of the so-called small round cell tumors of childhood. Histologic examination confirmed the cytologic diagnosis.

CONCLUSION

Cytologic, histologic and electron microscopic findings were identical to those described previously for embryonal rhabdomyosarcoma at other sites. In immunochemical examinations, cytologic samples fixed in ethanol are more useful than histologic ones fixed in formalin. Then, in order to differentiate poorly differentiated rhabdomyosarcoma from other small round cell tumors in children, desmin and alpha-sarcomeric actin, rather than myoglobin, are recommended.

Cerebral extracellular lactate concentration and blood flow during chemical stimulation of the nucleus tractus solitarii in anesthetized rats

The extracellular lactate concentration and blood flow in the cerebral cortex of urethane-anesthetized, paralyzed and artificially ventilated rats were monitored continuously and simultaneously using an enzyme electrode and a laser Doppler flowmeter (LDF), respectively, during chemical stimulation of the nucleus tractus solitarii (NTS) by microinjection of L-glutamate (1.7 nmol 50 nl). Chemical stimulation of the NTS significantly decreased the arterial blood pressure (ABP) from 85 +/- 17 to 68 +/- 14 mmHg, heart rate from 418 +/- 13 to 402 +/- 19 beats x min(-1) and cerebral blood flow (CBF) by 17.9 +/- 6.2% (P < 0.001). However, chemical stimulation of the NTS significantly increased the lactate concentration by 58.9 +/- 17.3 microM (P < 0.001). Barostat maneuver, which held systemic ABP constant during chemical stimulation of the NTS attenuated the responses in CBF and lactate concentration by 30 and 27%, respectively. The onset of the increase in lactate concentration was delayed about 19 s after that of the CBF decrease. Circulatory lactate produced no significant change in the cerebral extracellular lactate concentration. These results indicate that chemical stimulation of the NTS induces an increase in extracellular lactate concentration in the cerebral cortex through a decrease in CBF via cerebral vasoconstriction.

Cytologic features of solid and cystic tumor of the pancreas

OBJECTIVE

To describe the cytologic features of solid and cystic tumor of the pancreas.

STUDY DESIGN

Cytologic features of four cases of solid and cystic tumor of the pancreas (SCT) were reported and compared with those of three cases of islet cell tumor of the pancreas.

RESULTS

Aspiration and imprint cytology of the tumor cells obtained from three cases of SCT showed papillary structures or rosette formations in part and demonstrated uniformly round to oval nuclei that contained finely granular chromatin, a fairly distinct nucleolus and a scant to moderate amount of granular or vesicular cytoplasm. Another case of SCT consisted of multinucleated giant cells with coherent chromatin as well as mononuclear cells with nuclear grooves. Islet cell tumor consisted mainly of clustered or isolated uniform mononuclear cells with rosette formations but without a papillary structure and occasional multinucleated giant cells in all cases. The nuclei of islet cell tumors had peculiar, fine chromatin aggregates with a "salt-and-pepper" appearance and slightly enlarged nucleoli.

CONCLUSION

SCT is cytologically distinguishable from islet cell tumor in spite of having many cytologic features in common with it.

Mechanism of thrombocytosis in hepatoblastoma: a case report

Although thrombocytosis has long been recognized as a common finding in children with hepatoblastoma, its mechanism is still unknown. In this study, to confirm the role of thrombopoietin (Tpo) in the thrombocytosis in hepatoblastoma, the expression of Tpo mRNA in tumor cells was examined and the serum Tpo level was analyzed during the course of the disease. A 1-year, 6-month-old girl was diagnosed as having advanced hepatoblastoma. At diagnosis, she had marked thrombocytosis with 1220 x 10(9)/microL. After resection of the tumor and after four courses of chemotherapy, the level of alpha-fetoprotein normalized but the platelet count remained high. However, after the fifth course of chemotherapy, the platelet count decreased and normalized within 3 months. By enzyme-linked immunosorbent assay, the serum Tpo level was not high at diagnosis, whereas high Tpo levels were observed after chemotherapy. By polymerase chain reaction, Tpo mRNA was detected in both normal liver and tumor tissues, but the level of expression was not different between them. Therefore, in hepatoblastoma the serum Tpo level is not correlated with a high platelet count, and there is no difference in Tpo expression between normal liver and tumor tissues. Other unknown factors and their production sites to induce thrombocytosis should be examined in further studies.

Detection of respiratory frequency in the recordings of electrocardiogram, blood pressure or sympathetic nerve activity in the conscious rat

We extracted the respiratory frequency in conscious rats from variations of blood pressure, electrocardiogram, or renal sympathetic nerve activity by means of a band-pass filter. The frequency derived from any one of these parameters corresponded to directly recorded respiratory chest movements. The method may be useful when respiration and cardiovascular parameters have to be recorded in small animals during steady state when minimal surgical intervention is crucial.

Cerebral blood flow decreases following microinjection of sodium nitroprusside into the nucleus tractus solitarii of anesthetized rats

The present study was undertaken to examine the effects of microinjection of sodium nitroprusside (SNP), which releases nitric oxide (NO) spontaneously, into the nucleus tractus solitarii (NTS) on cerebral circulation. Cerebral blood flow (CBF) was measured in urethane-anesthetized (1.5 g middle dotkg-1, i.p.), paralysed and artificially ventilated rats using labeled microspheres or laser Doppler flowmetry. The CBF was significantly decreased by microinjection of SNP (5 nmol, n=10, microsphere technique; 0.5 nmol, n=6, laser Doppler flowmetry) into the unilateral NTS. Microinjection of NG-monomethyl-L-arginine (L-NMMA), an inhibitor of the formation of NO, prevented cerebral vasoconstrictor responses induced by microinjection of L-glutamate into the NTS (n=10). Microinjection of NG-monomethyl-D-arginine (D-NMMA) had no effect on the cerebral vasoconstrictor responses induced by L-glutamate (n=11). Unilateral microinjections of L-NMMA into the NTS (n=9), of SNP into the area adjacent to the NTS (n=9), of vehicle solution into the NTS (n=10), and of light-inactivated SNP into the NTS (n=6) had no effect on cerebral circulation. Cerebral autoregulation was well maintained in our protocols (n=9). These results indicate that microinjection of SNP, an NO donor, into the NTS decreases CBF.

Mutations in the TRKA/NGF receptor gene in patients with congenital insensitivity to pain with anhidrosis

Congenital insensitivity to pain with anhidrosis (CIPA; MIM 256800) is an autosomal-recessive disorder characterized by recurrent episodes of unexplained fever, anhidrosis (absence of sweating) and absence of reaction to noxious stimuli, self-mutilating behaviour and mental retardation. The genetic basis for CIPA is unknown. Nerve growth factor (NGF) induces neurite outgrowth and promotes survival of embryonic sensory and sympathetic neurons. Mice lacking the gene for TrkA, a receptor tyrosine kinase for NGF, share dramatic phenotypic features of CIPA, including loss of responses to painful stimuli, although anhidrosis is not apparent in these animals. We therefore considered the human TRKA homologue as a candidate for the CIPA gene. The mRNA and genomic DNA encoding TRKA were analysed in three unrelated CIPA patients who had consanguineous parents. We detected a deletion-, splice- and missense-mutation in the tyrosine kinase domain in these three patients. Our findings strongly suggest that defects in TRKA cause CIPA and that the NGF-TRKA system has a crucial role in the development and function of the nociceptive reception as well as establishment of thermoregulation via sweating in humans. These results also implicate genes encoding other TRK and neurotrophin family members as candidates for developmental defect(s) of the nervous system.